WO2025008817A1

WO2025008817A1 - Accessories for circular connectors

Info

Publication number: WO2025008817A1
Application number: PCT/IL2024/050647
Authority: WO
Inventors: Rafi Lagziel; Israel INGBER; Eyal Peleg
Original assignee: Israel Aerospace Industries Ltd.
Priority date: 2023-07-04
Filing date: 2024-07-03
Publication date: 2025-01-09
Also published as: IL304246A

Abstract

A coupler is provided for a circular connector having first and second cylindrical connection elements, the coupler including a first coupler element, a second coupler element and an engagement arrangement. When the first coupler element and the second coupler element are connected to the first connection element and the second connection element, respectively, the engagement arrangement is configured to permit axial translation of the first and second connection elements along the common connector axis into a connected configuration, conditional on at least a number of conditions for engagement being fulfilled.

Description

ACCESSORIES FOR CIRCULAR CONNECTORS

TECHNOLOGICAL FIELD

The present disclosure relates to circular connectors, in particular to circular connectors that include an electrical arrangement configured for interconnecting between electrical cables via electrical connector elements, for example pin connectors.

BACKGROUND

Circular connectors, also known as cylindrical connectors, are a well known arrangement in the art for enabling interconnection of certain types of electrical components, to thereby enable transmission of analog or digital data, electrical signals or electrical power, for example, between multiple cables, between a circuit box and cables, and the like, especially in avionics applications.

The circular connector types are commonly classified according to their receptacle housing, for example cable plugs, in-line receptacles, box-mounted receptacles, panelmounted receptacles, bulkhead feed-through, blind-mate connectors and PCB mount connectors.

Conventionally, such connectors comprise two generally cylindrical connector parts, in which a first connector part accommodates a male electrical connector part of an electrical arrangement, and the second connector part accommodates a female connector element of the electrical arrangement. For example such an electrical arrangement can be in the form of an 8-pin connector, or crimped removable pins, or PCB pins, or fixed pin contacts.

Such connectors can also come in different sizes, such as to enable different numbers of pins/sockets to be interconnected.

In practice, the same type of electrical arrangement can be provided to a plurality of cylindrical connectors, such that the first connector part is physically compatible with more than one second connector part, which can lead to errors occurring in which a first connector part is connected to the wrong second connector part.

Some manufacturers produce a plurality of different connectors, each connector having a different, integrally formed, alignment arrangement to avoid such errors, but such a solution requires many different connectors to be manufactured, and stocked by the user, which can have logistical and cost implications. In other cases, the pattern of which one of the male or female connector element is provided in the junction box can be inverted for some of the connectors to minimize connection errors, which can have limited utility in avoiding such errors, and which complicates the arrangements at the junction box itself.

GENERAL DESCRIPTION

According to a first aspect of the present disclosure, there is provided a coupler for a circular connector, the circular connector comprising a first generally cylindrical connection element having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; the coupler comprising: a first coupler element connectable to the first connection element, the first coupler element comprising a first portion of an engagement arrangement, the first portion comprising a first geometrical configuration; and a second coupler element connectable to the second connection element, the second coupler element comprising a second portion of the engagement arrangement, the second portion comprising a second geometrical configuration; and wherein, when the first coupler element and the second coupler element are connected to the first connection element and the second connection element, respectively, the engagement arrangement is configured to permit axial translation of the first and second connection elements along the common connector axis into the connected configuration, conditional on at least the following conditions for engagement being fulfilled: a) the first geometrical configuration is complementary to, matches or corresponds to the second geometrical configuration at least in an axial direction parallel with common connector axis, so as to fit together when brought together in an axial direction along the common connector axis; an b) the first connection element and the second connection element are coaxially aligned along the common connector axis; and c) the first and second portions of the engagement arrangement are in an engaging enabling position, in which they are oriented about the common connector axis at corresponding angular orientations so as to fit together when brought together in an axial direction along the common connector axis.

For example, each of the first and second coupler elements, when connected to the respective first and second connection element, is constrained with respect to the respective connection element in: preventing relative movement in an axial direction along the respective central longitudinal axis; and preventing relative movement in a radial direction from the respective central longitudinal axis.

In some examples, each of the first and second coupler elements, when connected to the respective first and second connection element, is constrained with respect to the respective connection element also in preventing relative movement in a circumferential direction about the respective central longitudinal axis; Additionally or alternatively for example, the engagement arrangement acts as a limiter preventing the connection elements when connected to the coupler elements from being brought into the connected configuration unless the conditions for engagement are fulfilled.

Additionally or alternatively for example, at least one of the first and second portions of the engagement arrangement comprises at least one projection and at least the other of the first and second portions of the engagement arrangement comprises a corresponding at least one recess; configured to receive the at least one projection; wherein, in use, when the coupler elements are connected to the respective connection elements:

- the at least one projection extends in a direction parallel to the common connector axis; and

- the at least one recess is configured to receive the at least on projection in the connected configuration.

Additionally or alternatively for example, in at least a first example the first and second coupler elements are configured to be mounted to a cylindrical outer surface of the respective first and second connection elements. For example, each of the first and second coupler elements comprises a hollow annular body comprising a central longitudinal axis. For example, the hollow annular body comprises at least two arc-shaped members and the arc-shaped member are connected in a hinged manner at one end and configured with a snap-fit closure at the other. Alternatively, the hollow annular body comprises at least two arc-shaped members and the two arc-shaped member are configured at both ends with snap-fit closures.

Additionally or alternatively for example, in at least a second example, the first coupler element comprises a first annular plate configured to be mounted to an axial end surface of the first connection element; and wherein the second coupler element comprises a second annular plate configured to be mounted to the second connection element; wherein the first annular plate comprises at least one through-bore passing through a thickness of said plate, and the second annular plate is provided with at least one protrusion configured to extend orthogonal to a surface of said second annular plate; wherein, when the conditions for engagement are fulfilled, the first and second annular plates can be brought together, such that the at least one protrusion is configured to be at least partially received in the at least one through-bore.

For example, the at least one protrusion is configured to taper in a direction away from said second annular plate.

Additionally or alternatively for example, the at least one through-bore comprises at least two through-bores located at predetermined relative angular locations about a central axis of said first annular plate, and wherein the at least one protrusion comprises at least two protrusions configured to be located at predetermined relative angular locations about a central axis of said second annular plate configured to correspond with the predetermined relative angular locations of the at least two through-bores.

In at least a third example, the first coupler element comprises at least one non- rotationally symmetric recess extending therein when viewed along an axis of the at least one recess; and wherein the second coupler element comprises at least one protrusion configured to be mounted to the second connection element, the at least one protrusion configured to extend parallel to an axis of the second connection element, wherein the at least one protrusion comprises a non-rotationally symmetric cross-section taken orthogonal to an axis of the protrusion; wherein, when the conditions for engagement are fulfilled, the at least one protrusion can be passed at least partially through the at least one recess.

For example, the at least one protrusion is configured to taper along the axis thereof. Additionally or alternatively for example, the at least one non-symmetrical recess comprises at least two non-symmetric recesses configured to be located at predetermined relative angular locations about the first longitudinal central axis of the first connection element, and wherein the at least one protrusion comprises at least two protrusions configured to be located at predetermined relative angular locations about the second longitudinal central axis of the second connection element configured to correspond with the predetermined relative angular locations of the recesses configured to receive the at least two protrusions.

In at least a fourth example, the first coupler element has a hollow cylindrical shape and comprises a central longitudinal axis, and wherein the first geometrical configuration comprises at least one of a longitudinally extending groove or a protrusion; and wherein the second coupler element has a hollow cylindrical shape and comprises a central longitudinal axis, and wherein the second geometrical configuration comprises at least the other of the longitudinally extending groove or the protrusion; wherein, when the conditions for engagement are fulfilled, the first and second coupler elements, when fixed to the respective first and second connection elements, can be brought together, such that the protrusion is configured to be at least partially received in the groove.

The fourth example can be of particular use where the number of pins/sockets of the electrical connection arrangement is small. Alternatively, a circular connecter having a relatively large internal diameter and generally used for a large number of pins/sockets can be used with a relatively smaller number of pins/sockets when implementing the third example.

For example, the protrusion comprises a key extending longitudinally along the respective coupler element.

Additionally or alternatively for example, each of the first and second coupler elements further comprises a flange configured to facilitate fixing of the respective first and second coupler element within the respective first or second connection element. Additionally or alternatively for example, each of the first and second coupler elements comprises a plurality of protrusions or grooves located at predetermined angular locations about the respective central axis.

Additionally or alternatively for example, at least a portion of the coupler is made from at least one of

- a polymer material, optionally a plastics material; and

- a metal, optionally any one of steel, aluminium or titanium;

- a composite material of other fiber-reinforced material.

Additionally or alternatively for example, the coupler is configured to be retrofitted on a pre-existing circular connector.

Additionally or alternatively for example, the coupler is suitable for use with any one of a MIL-DTL-38999 circular connector, a micro miniature D38999 circular connector or any other suitable mating by turn connector.

According to a second aspect of the presently disclosed subject matter, there is provided a circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is operatively connected with a coupler as defined herein. According to the second aspect of the presently disclosed subject matter, there is also provided a circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler as defined herein according to the first example; wherein the first coupler element is externally affixed with respect to the first connection element, and wherein the second coupler element is externally affixed with respect to the second connection element.

According to the second aspect of the presently disclosed subject matter, there is also provided a circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler according defined herein regarding the second example; wherein the first connection element comprises an annular axial end surface comprising a plurality of bores, the annular axial end surface being configured to receive thereon the first annular plate; and wherein the second connection element is configured to receive the second annular plate.

For example, the plurality of bores comprises a plurality of blind-bores.

Alternatively for example, the plurality of bores comprises a plurality of through- bores.

According to the second aspect of the presently disclosed subject matter, there is also provided a circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler as defined herein regarding the third example; wherein the first connection element comprises an axial end surface configured to receive the first coupler element; and wherein the second connection element is configured to receive the second coupler element.

According to the second aspect of the presently disclosed subject matter, there is also provided a circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler as defined herein regarding the fourth example; wherein the first connection element comprises a first annular space around one or more electrical connection elements, the first annular space being configured for receiving the first coupler element; and wherein the second connection element comprises a second annular space around one or more electrical connection elements, the second annular space being configured for receiving the second coupler element.

For example, the circular connector comprises any one of a MIL-DTL-38999 circular connector, a micro miniature D38999 circular connector or any other suitable mating by turn connector.

According to a third aspect of the presently disclosed subject matter, there is also provided a kit comprising a plurality of couplers, wherein each coupler is as defined herein, wherein the first portion of the engagement arrangement of one of the plurality of couplers is incompatible with the second portion of the engagement arrangement of at least one other coupler of the plurality of couplers.

According to the third aspect of the presently disclosed subject matter, there is also provided a kit comprising a plurality of couplers, wherein each coupler is as defined herein, wherein the first geometrical form of the first portion of the engagement arrangement of one of the plurality of couplers is incompatible with the second geometrical form of the second portion of the engagement arrangement of at least one other coupler of the plurality of couplers. For example, a colour of the first coupling element of one of the plurality of couplers does not match a colour of the second coupling element of at least one other coupler of the plurality of couplers.

According to a third aspect of the presently disclosed subject matter, there is also provided a kit comprising a plurality of circular connectors and a plurality of couplers as defined herein regarding the first example.

According to a third aspect of the presently disclosed subject matter, there is also provided a kit comprising a plurality of circular connectors and a plurality of couplers as defined herein regarding the second example; wherein, in use, the first annular plate is mounted to the first connection element such that the at least one through-bore of the annular plate is selectively aligned with a respective at least one bore of the plurality of bores in the respective connection elements; and wherein, in use, the at least one protrusion of the second annular plate is selectively mounted thereon, so as to extend orthogonally therefrom, at angular locations around the second annular plate corresponding to the at least one through-bore.

According to a third aspect of the presently disclosed subject matter, there is also provided a kit comprising a plurality of circular connectors and a plurality of couplers as defined herein regarding the third example; wherein, in use, the first coupler element comprising the non-symmetrical recess is fixed to the first connection element at a rotational orientation selected by the user; and wherein, in use, the at least one non-symmetrical protrusion is selectively fixed to the second connection element at a rotational orientation selected by the user, so as to correspond with the rotational orientation of the at least one recess selected by the user.

According to a third aspect of the presently disclosed subject matter, there is also provided a kit comprising a plurality of circular connectors and a plurality of couplers as defined in defined herein regarding the second example. A feature of at least one example of the presently disclosed subject matter is that circular connectors of the same type can be essentially coded using different pairs of matching coupler elements, which can prevent the respective cables from being incorrectly connected to their connections.

Another feature of at least one example of the presently disclosed subject matter is that the pairs of matching coupler elements can be mounted or fixed to a single type of circular connector, which can enable the provision of multiple differently-coded circular connectors while only needing to store or stock a single type of circular connector.

Another feature of at least one example of the presently disclosed subject matter is that a user can selectively apply pairs of matching coupler elements to circular connectors as needed in the field, which enables greater flexibility in providing the desired coding to circular connectors.

Another feature of at least one example of the presently disclosed subject matter is that the coupler elements can be cheap to manufacture, which enables provision of a more economical coding system.

Another feature of at least one example of the presently disclosed subject matter is that the coupler elements can be retrofit to pre-existing circular connectors, which enables easy coding of pre-existing connectors without the need for replacement.

Another feature of at least one example of the presently disclosed subject matter is that there is no need to acquire a variety of connectors that are integrally coded in a different manner one with respect from another at factory, and instead the same basic model of connector can be used for all the connectors in an electric box, and wherein different couplers are used for each connector. This can provide logistic and/or cost advantages over conventional practice, by reducing the variety of connector stock that is required for any given application, and such an effect can be multiplied when considering that the requirement for a variety of elements to which the connectors can be connected to can also be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosed herein and to exemplify how it can be carried out in practice, examples will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig- 1 shows schematically an example of an electrical/avionics junction box arrangement example for use with a plurality of circular connectors that are connected to a plurality of cables.

Fig. 2 shows in isometric view an example of a circular connector having first and second connection elements, wherein the circular connector is in a disconnected configuration.

Fig. 3 shows in isometric view the example of Fig. 2, in a connected configuration;

Fig. 4 shows in isometric view, the circular connector example of Fig. 2 in the disconnected configuration, and including a coupler according to a first example of the presently disclosed subject matter.

Fig. 5 shows in isometric view a first coupler element of the coupler example of Fig. 3.

Fig. 6 shows in isometric view a second coupler element of the coupler example of Fig. 3.

Fig. 7 shows in isometric view a first connection element of a second example of a circular connector, in conjunction with a first coupler element of a coupler according to a second example of the presently disclosed subject matter.

Fig. 8 shows in isometric view a second connection element of the circular connector example of Fig. 7, in conjunction with a second coupler element of the coupler according to the second example of the presently disclosed subject matter.

Fig. 9 shows in partial detail isometric view a first coupler element of a third coupler according to a third example of the presently disclosed subject matter.

Fig. 10 shows in isometric view of a second coupler element of the coupler according to the third example of the presently disclosed subject matter.

Fig. 11 shows in isometric view a portion of the second coupler element of the coupler example of Fig. 10.

Fig. 12A shows in isometric view a first connection element of a third example of a circular connector, in conjunction with a first coupler element of a coupler according to a fourth example of the presently disclosed subject matter; Fig. 12B shows in isometric view a second connection element of the circular connector example of Fig. 12 A, in conjunction with a second coupler element of the coupler according to the fourth example of the presently disclosed subject matter.

Fig. 13 schematically illustrates a kit according to an example of the presently disclosed subject matter.

DETAILED DESCRIPTION

As shown schematically in Fig. 1, a junction box or panel 2 comprises a plurality of first connection elements 4 each of which is a part of a respective circular connector 10 (also referred to interchangeably herein as a cylindrical connector). A plurality of second connection elements 6, each of which is the respective second connecting part of the respective circular connector, are configured to be connected to the respective second connection elements 4. In at least this example, the second connection elements 6 are each connected to a cable 8 or the like, while first connection elements 4 , for example in the form of plugs, are each connected to specific electrical or electronic components, for example in the form of a junction box, for example an electrical/electronic/avionics junction box, that can have different electrical ratings one to another, for example.

Each circular connector 10 accommodates two parts of a respective electrical connection arrangement, one part of the electrical connection arrangement being accommodated in the respective first connector element 4, and the second part of the electrical connection arrangement being accommodated in the respective second connector element 6. Each respective electrical connection arrangement provides electrical and/or electronic continuity across the connector 10 when the respective pair of first and second connection elements 4, 6, are axially fully engaged with one another.

For example, the electrical connection arrangement can be in the form of male and female connectors. For example, one part of the electrical connection arrangement can include a particular pin arrangement - for example an 8-pin arrangement in which the pins are arranged in three rows, while the other part of the electrical connection arrangement can include a complementary socket arrangement - for example an 8-socket arrangement in which the sockets are arranged in complementary positions corresponding to the pins.

However, the arrangement of electrical connections such as pins and sockets in each of the pairs of connection elements 4, 6 can be such that first connection element 4 of some circular connectors 10 could be physically compatible with the respective second connection elements 6 of more than one circular connector 10, which could potentially lead to incorrect connections between a first connection element 4 of one circular connector 10 the respective second connection elements 6 of a different, and thus incorrect, circular connector 10, which in turn can result in the different cables 8 being electrically coupled to the wrong components of the junction box.

According to an aspect of the presently disclosed subject matter, and in order to minimize the risk and preferably prevent accidental physical connection of the wrong first and second connector elements 4, 6 (i.e. that do not belong to the same circular connector 10) together, respective accessories in the form of couplers are provided, and examples of which are disclosed below by way of non-limiting examples. In such examples, differently-coded couplers can be provided for a set of identical connectors, thereby essentially coding the generic connectors in a non-integral manner. In other words, the respective couplers are each non-integral with respect to the respective circular connectors, and the circular connectors can be formed and provided without such couplers being attached thereto; rather, the couplers can be affixed to the respective connectors when desired, and optionally the couplers can be removed from the circular connectors in a non-destructive way, enabling the circular connector to still interconnect the two connector portions thereof in the conventional manner.

It is to be noted that the couplers according to the presently disclosed subject matter are not an integral part of any circular connector per se, and each coupler is separate from, distinct and different from the circular connector per se.

Referring to Figs. 2 and 3, there is shown a circular connector 20 (also referred to interchangeably herein as a cylindrical connector) according to an example of the presently disclosed subject matter. The circular connector 20 comprises a first generally cylindrical connection element 40 (for example in the form of a receptacle) and a second generally cylindrical connection element 60 (for example in the form of a plug). Each of the first and second connection elements 40, 60, comprises a respective longitudinal central axis, such that the first connection element 40 comprises a first longitudinal central axis LCA1 and the second connection element 40 comprises a second longitudinal central axis LCA2.

Fig. 2 illustrates the first and second connection elements 40, 60 in a disconnected configuration DC, in which the first and second connection elements 40, 60 are not full mated with one another and are electrically disconnected from one another, i.e., the respective two parts of the respective electrical connection arrangement, each part being accommodated in a different one of the first connection element 40 and the second connection element 60, are not in electrical or electronic communication. Thus, for example, in the disconnected configuration DC the respective male pins of one connection element are fully disengaged from, or at least not fully received inside, the respective female sockets of the other connection element.

Fig. 3 illustrates the first and second connection elements 40, 60 in a connected configuration CC, in which the first and second connection elements 40, 60 are coaxially aligned so as to have a common connector axis CCA, and in which the first and second connection elements 40, 60 are fully mated with one another so as to permit electrical connection therebetween. In other words, in the connected configuration CC the respective two parts of the respective electrical connection arrangement are in electrical or electronic communication. Thus, for example, in the connected configuration CC the respective male pins of one connection element are fully received inside, the respective female sockets of the other connection element.

Such mating can include, but is not limited to, an arrangement of pin and socket connections, or other male-female electrical arrangements as known to the skilled person.

The first and second connection elements 40, 60 can further be provided with locking arrangement to help retain the connection elements 40, 60 in the connected configuration. The locking arrangements could, for example, take the form of helical threads provided on each of the first and second connection elements 40, 60, a bayonet fitting, a blind mate locking mechanism, or other locking arrangements known to the skilled person. In the event that helical threads are provided, a torque limiting mechanism can be additionally provided to prevent over-tightening of the connection between the first and second connection elements 40, 60.

At least one of the first and second connection elements 40, 60, for example the second connection element 60, can be provided with a locking ring 62, which can be turned about the second longitudinal central axis LCA2 to advance and fully lock the first and second connection elements 40, 60 together axially in the connected configuration CC. The locking ring 62 can comprise an outer textured surface to enable a user to better grip the connection elements 40, 60 in order to enable ease of connection and disconnection. In at least some alternative variations of this example, the first and second connection elements 40, 60 can be provided with any suitable arrangement or preparation that is compatible with a tightening tool.

Furthermore, the first and second connection elements 40, 60 can be provided with alignment arrangement that compels the first and second connection elements 40, 60 to be aligned circumferentially with respect to one another (when also co-axially aligned with one another) in order to enable the first and second connection elements 40, 60 to come together to provide the connected configuration CC. For example, the first connection element 40 can be provided with a number of keys axially parallel with respect to the first longitudinal central axis LCA1, and the second connection element 60 can be provided with complementary keyways that are also axially parallel with respect to the second longitudinal central axis LCA2. The various keys are complementary to the respective keyways and are circumferentially located with respect to the first and second connection elements 40, 60 such that when the first and second connection elements 40, 60 are properly aligned, the keys slide into the respective keyways enabling the first and second connection elements 40, 60 to interconnect in the connected configuration CC. In this manner, it is ensured that the respective parts of electrical arrangement are also aligned and can electrically connect with one another properly. On the other hand, if the first and second connection elements 40, 60 are not circumferentially aligned, the mismatched alignment arrangement, for example the mismatched keys and keyways will not allow the first and second connection elements 40, 60 to come together and the circular connector 20 will be unable to transition to the connected configuration CC. Such alignment arrangements are integrally provided in the circular connector 20, and are distinct from the coupler of the presently disclosed subject matter.

While there can be many kinds of applications for circular connectors, in this particular example, the first connection element 40 is of the kind to pass through a structural element such as a wall, barrier or the like, while the second connection element 60 is of the kind to be connected to the end of a cable, fibre optic transmission line or the like.

The circular connector can, for example, be capable of transferring data, power, signals, or the like between the two connection elements 40, 60, for example via coaxial connectors or pin/socket connectors wherein at least some such pins can also be in the form of coaxial connectors.

Since, in at least some applications, multiple circular connectors, having the same internal electrical connection arrangement, can be used in a single application, for example in a connector box, bulkhead or the like, care must be taken in order to avoid connecting the wrong second connection element 60 to the wrong first connection element 40, to ensure correct electrical connections are made.

According to an aspect of the presently disclosed subject matter, and in order to minimize the risk and preferably prevent accidental physical connection of the wrong first and second connector elements 40, 60 to one another (i.e. to prevent physical connection of first and second connector elements 40, 60 that do not belong to the same circular connector 20), the generic circular connector 20 can be provided with a coupler (also referred to herein interchangeably as an accessory), a few non-limiting examples of which will now be described in conjunction with the drawings.

With reference to Figs. 4 to 6, there is provided a coupler according to a first example of the presently disclosed subject matter, generally designated 100. The coupler 100 comprises a first coupler element 100A, which is connectable to the first connection element 40, and a second coupler element 100B, connectable to the second connection element 60.

As will become clearer herein, the coupler 100 comprises a unique engagement arrangement 140 that allows only the matched pair of the first coupler element 100A and the second coupler element 100B to be coupled to one another, and generally prevents a respective first coupler element of one such coupler to be coupled to a respective second coupler element of a different coupler. Thus, the coupler 100 essentially provides an external, or non-integral coding option to differentiate properly coded connectors from other connectors.

With particular reference to Fig. 5, in this example, the first coupler element 100A comprises a first arc-shaped member 110A and a second arc-shaped member 120A. The first arc-shaped member 110A comprises a respective first end 111A and a respective second end 112A, while the second arc-shaped member 120A comprises a respective first end 121 A and a respective second end 122A. In at least this example, the first end 111A of the first arc-shaped member 110A and the first end 121 A of the second arc-shaped member 120A are hingedly connected to one another via a pivot 130A, allowing relative pivoting motion between the first arc-shaped member 110A and the second arc-shaped member 120A about the pivot 130A.

In at least this example, the angle subtended by each of the first and second arcshaped members 110A, 120A is nominally 180°. However, in at least some alternative variations of this example, the respective first coupler element can include more than two arc-shaped members hingedly connected to one another, each subtending an angle of 180° or less, so that the sum of the angles subtended by the respective arc-shaped members is 360°.

The first coupler element 100A includes a respective first locking arrangement for selectively (and optionally reversibly) locking together the second end 112A of the first arc-shaped member 110A and the second end 122A of the second arc-shaped member 120A.

The second end 112A of the first arc-shaped member 110A is provided with a cantilever projection 113A having a stepped lug 117A at the end of the cantilever projection 113A, while the second end 122A of the second arc-shaped member 120A is provided with a recess 123A having a locking step 124A (not visible in the angle of view of Fig. 5, but comparable to the locking step 117B shown in Fig. 6). In at least some alternative variations of this example, different locking arrangements can be provided, for example screws, zip ties, cable ties, latch mechanisms, butterfly lock plug, adhesive, nuts/bolts, rivets and so on.

When the first and second arc-shaped members 110A, 120A are rotated about the pivot 130A so as to bring the second ends 112A, 122A towards one another, the cantilever projection 113A enters the recess 123A and the stepped lug 117A creates a cantilever snap-fit with the locking step 124A, so as to lock the coupler element 100A in a closed position. In this manner, the first coupler element 100A can be fixedly fitted in a snug manner around the first connection element 40 in a manner preventing relative translation or rotation between the first coupler element 100A and the first connection element 40.

Optionally, the snap-fit can be released by simply biasing the cantilever projection 113A so that the stepped lug 117A moves away from the locking step 124A, thereby permitting the cantilever projection 113A to be removed from the recess 123A and the first and second arc-shaped members 110A, 120A to be rotated about the pivot 130A so as to separate the second ends 112A, 122A from one another.

While in at least this example, the recess 123A is provided on the second arcshaped member 120A and the cantilever projection 113A is provided on the first arcshaped member 110A, in at least some alternative variations of this example, the reverse arrangement can instead be provided, for example in which the recess is provided on the first arc-shaped member and the cantilever projection is provided on the second arcshaped member. In yet other alternative variations of this example, the pivot arrangement can be replaced with a second locking arrangement, similar for example to the first locking arrangement.

While in at least this example, the locking between the first and second arc-shaped members 110A, 120A is provided by a snap-fit connection, in at least some other alternative variations of this example, different locking arrangements can be provided for interconnecting the arc shaped members together, for example other conventional locking arrangements known to the skilled person, for example as screws, nuts bolts, glue, adhesive, rivets other fixings and fittings and the like. The first coupler element 100A comprises a first portion 140A of the engagement arrangement 140. The first portion 140A comprises a first geometrical configuration, which in this example is provided by two radial recesses 142A, 144A located on a radially inner side RI of a circumferentially extending wall 115A of the first arc-shaped member 110A

In at least this example, the radial recesses 142A, 144A each have a uniform crosssection that extends axially parallel to the respective first longitudinal central axis LCA1.

In at least this example, the radial recesses 142A, 144A subtend an angle a therebetween. The two radial recesses 142A, 144A are provided on an axial end-surface 114A of the first arc-shaped member 110A, and when connected to the first connection element 40, the axial end-surface 114A is arranged to face towards the second connection element 6O.With particular reference to Fig. 6, in at least this example, the second coupler element 100B comprises a first arc-shaped member HOB and a second arc-shaped member 120B. The first arc-shaped member HOB comprises a first end 111B and a second end 112B, while the second arc-shaped member 120B comprises a first end 121B and a second end 122B. The first end 11 IB of the first arc-shaped member HOB and the first end 121B of the second arc-shaped member 120B are hingedly connected by means of a pivot 130B, allowing rotation thereabout. In at least some alternative variations of this example, the hinged connection can be replaced with any suitable locking arrangements can be provided, for example similar to the arrangement for selectively (and optionally reversibly) locking together the second end 112A of the first arc-shaped member 110A and the second end 122A of the second arc-shaped member 120A as disclosed above, mutatis mutandis, or alternatively screws, zip ties, cable ties, latch mechanisms, butterfly lock plug, adhesive, nuts/bolts, rivets and so on.

In at least this example, the angle subtended by each of the first and second arcshaped members HOB, 120B is nominally 180°. However, it in at least some alternative variations of this example, the respective first coupler element can include more than two arc-shaped members hingedly connected to one another, each subtending an angle of 180° or less, so that the sum of the angles subtended by the respective arc-shaped members is 360°. The second coupler element 100B includes a respective second locking arrangement for selectively (and optionally reversibly) locking together the second end 112B of the first arc-shaped member HOB and the second end 122B of the second arcshaped member 120B.

The second end 112B of the first arc-shaped member HOB is provided with a recess 113B having a locking step 117B, while the second end 122B of the second arcshaped member 120B is provided with a cantilever projection 123B having a stepped lug 124B at the end of the cantilever projection 123A.

When the first and second arc-shaped members HOB, 120B are rotated about the pivot 130B so as to bring the second ends 112B, 122B towards one another, the cantilever projection 123B enters the recess 113B and the stepped lug 124B creates a cantilever snap-fit with the locking step 117B, so as to lock the coupler element 100B in a closed position. In this manner, the second coupler element 100B can be fixedly fitted in a snug manner around the second connection element 60 in a manner preventing relative translation or rotation between the second coupler element 100B and the second connection element 60.

Optionally, the snap-fit can be released by simply biasing the cantilever projection 123B so that the stepped lug 124B moves away from the locking step 117B, thereby permitting the cantilever projection 123B to be removed from the recess 113B and the first and second arc-shaped members HOB, 120B to be rotated about the pivot 130B so as to separate the second ends 112B, 122B from one another.

While in at least this particular example, the recess 113B is provided on the first arc-shaped member HOB and the cantilever projection 123B is provided on the second arc-shaped member 120B, in at least some alternative variations of this example, the reverse arrangement can instead be provided, for example in which the recess is provided on the second arc-shaped member and the cantilever projection is provided on the first arc-shaped member. In yet other alternative variations of this example, the pivot arrangement can be replaced with a second locking arrangement, similar for example to the first locking arrangement of the second coupler element. While in at least this example, the locking between the first and second arc-shaped members HOB, 120B is provided by a snap-fit connection, in at least some other alternative variations of this example, different locking arrangements can be provided for interconnecting the arc shaped members together, for example other conventional locking arrangements known to the skilled person, for example screws, zip ties, cable ties, latch mechanisms, butterfly lock plug, nuts/bolts, glue, adhesive, rivets other fixings and fittings and the like.

As can be seen in Fig. 6, in at least this example, the first arc-shaped member HOB is provided with a first cut-away portion 118B in an outer surface thereof, and the second arc-shaped member 120B is provided with a second cut-away portion 128B in an outer surface thereof. The first and second cut-away portions 118B, 128B enable a user to contact the locking ring 62 of the second connection element 60 in order to carry out any necessary relative rotation, for example a twisting motion, between portions of the first and second connection elements 40, 60 which will enable connection or disconnection, such as a helical threaded connection, bayonet connection or other connection known to the skilled person.

The second coupler element 100B comprises a second portion 140B of the engagement arrangement 140. The second portion 140B comprises a second geometrical configuration, which in this example is provided by two lugs 142B, 144B projecting radially outwardly from the first arc-shaped member HOB.

In at least this example, the lugs 142B, 144B each have a uniform cross-section that extends axially parallel to the respective second longitudinal central axis LCA2.

In at least this example, the two lugs 142B, 144B subtend an angle therebetween. The two lugs 142B, 144B are provided on an axial end-surface 114B of the first arcshaped member HOB, and when connected to the second connection element 60, the axial end-surface 114B is arranged to face towards the first connection element 40.

The cross-sectional profiles of each of the radial recesses 142A, 144A are complementary to the respective cross-sectional profiles of respective lugs 142B, 144B.

As can be seen in Fig. 4, when both the first coupler element 100A and the second coupler element 100B are connected to their respective first and second connection elements 40, 60, the axial end surfaces 114A, 114B are arranged to face towards one another.

Since in at least this example, the subtended angles a and p are the same, and since the cross-sectional profiles of each of the radial recesses 142A, 144A are complementary to the respective cross-sectional profiles of respective lugs 142B, 144B, when the first coupler element 100A and the second coupler element 100B are brought together coaxially, with the axial end surfaces 114A, 114B facing each other, the lugs 142A, 144A are arranged to enable them to slide into, or be received in, the respective recesses 142B, 144B

However, if non-matching coupler elements 100A, 100B are brought towards one another, where the angles a and do not match, and/or the cross-sectional profiles of each of the radial recesses are not complementary to the respective cross-sectional profiles of respective lugs, the lugs 142A, 144A will not coincide with the recesses 142B, 144B and instead will collide with the axial end surface 114B of the circumferentially extending wall 115B. This will limit the proximity of the respective mis-matched coupler elements 100A, 100B, and prevent the mis-matched coupler elements 100A, 100B from being brought together to be fully coupled, and hence when the mis-matched coupler elements 100A, 100B are connected to the wrong combination of first and second connection elements 40, 60, will prevent the wrong combination of first and second connection elements 40, 60 from being brought into the connected configuration. Accordingly, two connection elements which are provided with (and thus “coded” with) non-matching coupler elements, i.e., with non-matching geometrical configurations, physically cannot be fully connected to one-another, thereby preventing errors and accidental misconnection between the first connection element of one circular connector and the second connection element of a different circular connector.

Accordingly, when the properly matched first coupler element 100A and the second coupler element 100B are connected to the first connection element 40 and the second connection element 60, respectively, the engagement arrangement 140 is configured to permit axial translation of the respective and properly matched first and second connection elements 40, 60 along the common connector axis CCA into the connected configuration, conditional on at least the following conditions for engagement being fulfilled: a) the first geometrical configuration 140A is complementary to, matches or corresponds to the second geometrical configuration 140B at least in an axial direction parallel with common connector axis CCA, so as to fit together when brought together in an axial direction along the common connector axis CCA; b) the first connection element 40 and the second connection element 60 are coaxially aligned along the common connector axis CCA; and c) the first and second portions 140 A, 140B of the engagement arrangement 140 are in an engaging enabling position, in which they are oriented about the common connector axis at corresponding angular orientations so as to fit together when brought together in an axial direction along the common connector axis CCA.

The engagement arrangement 140 essentially acts as a limiter preventing the connection elements 40, 60 when connected to the coupler elements 100A, 100B from being brought into the connected configuration unless the conditions for engagement are fulfilled.

Alternatively or additionally, although in this example, the physical limit provided by the geometrical configurations is determined by a size of a subtended angle, it is envisaged that the limit can additionally or alternative also be provided by a non-matching size or cross-sectional profile, of a respective recess or lug.

Alternatively or additionally, although in this example, two lugs and recesses were provided, it is envisaged that there can alternatively be provided one, two, three, four, five or more recesses and lugs, which could be of varying sizes and shapes in profile.

Alternatively or additionally, although in this example, the lugs are provided on the first coupler element 100A and the recesses are provided on the second coupler element 100B, it is envisaged that these can be provided in the opposite manner, or alternatively, a combination of lugs and recesses could be provided on each of the coupler elements 100A, 100B. Since the coupler elements 100A, 100B are each provided with a snap-fit closure mechanism, when each coupler element 100A, 100B is closed around the respective connection element 40, 60, a snap-fit locking connection is made, by which a snug, interference fit is created between the coupler elements 100A, 100B and each respective connection element 40, 60. Thus, each of the first and second coupler elements 100A, 100B, when connected to the respective first and second connection element 40, 60, is constrained with respect to the respective connection element in: preventing relative motion in an axial direction along the respective central longitudinal axis; and preventing relative motion in a radial direction from the respective central longitudinal axis.

In at least some alternative variations of this example, each of the first and second coupler elements 100A, 100B, when connected to the respective first and second connection element 40, 60, is constrained with respect to the respective connection element in preventing relative motion in a circumferential direction about the respective central longitudinal axis.

The at least this example, the coupler 100 can be formed by injection molding or cast, for example. Alternatively, the coupler 100 can be produced by additive manufacture such as 3D printing, or subtractive manufacture such as machining, or the like.

In at least some examples, the coupler 100 could be formed of a polymer material, such as a plastics material, or a metal material such as aluminium, steel, titanium, composite materials (for example fiber reinforced materials) or the like. The respective hinges can be formed of the same material as the remainder of the coupler 100 or from a different material.

In at least some examples, the coupler 100 is configured to be snap-fit onto the outside of a circular connector, and so can be retrofit on a pre-existing circular connector, or could be used in combination with a new circular connector. Exemplary circular connectors in conjunction with which the first exemplary coupler 100 could be used can include, but are not limited to, any one of a MIL-DTL-38999 circular connector, a micro miniature D38999 circular connector or any other suitable mating by turn connector.

According to an aspect of the presently disclosed subject matter, there is provided a kit of couplers according to the first example, wherein each coupler 100 in the kit has a respective engagement arrangement 140 that is different from the respective engagement arrangement 140 of the other couplers 100 in the kit. This allows only the matched pair of the first coupler element and the second coupler element of the respective coupler to be coupled to one another, and generally prevents a respective first coupler element of one such coupler to be coupled to a respective second coupler element of a different coupler in the kit.

In this manner a user can use such a kit to selectively code each pair of connection elements of the respective circular connectors in a different manner with respect to one another, by using differently-coded couplers (i.e., in which the couplers each have respective engagement arrangements that are incompatible with respect to the engagement arrangement of the other couples, for example, having incompatible geometrical configurations). This feature enables a user to stock a single type of circular connector which is not specifically coded (in which the respective first connection elements are compatible with any second connection element of the other circular connectors), and to add-on the requisite number of cheap-to-produce, uniquely or differently coded couplers as required. In this way, an economical manner of producing a uniquely coded circular connector can be achieved, which can be tailored to the needs of the user.

Optionally, matching pairs of coupler elements can be colour coded in the same colour, but different from colour of the colour code of other coupler elements having different geometrical configurations.

Optionally, indicia or markings can be provided on an outer surface of the coupler elements to aid a user in aligning the coupler elements when making the electrical connections.

Referring to Figs. 7 and 8, a circular connector 220 (also referred to interchangeably herein as a cylindrical connector) according to a second example of the presently disclosed subject matter, comprises a first generally cylindrical connection element 240 and a second generally cylindrical connection element 260.

The first connection element 240 is similar to the first connection element 40 described above, mutatis mutandis, except for the recesses 242 and fastening holes 244 as will be described in more detail below. Hence, the above detailed description with respect to the first connection element 40 applies mutatis mutandis to the first connection element 240.

Similarly, the second connection element 260 is similar to the second connection element 60 described above, mutatis mutandis, except for fastening arrangements provided inside, as will be described in more detail below. Hence, the above detailed description with respect to the second connection element 60 applies mutatis mutandis to the second connection element 260.

As mentioned above, and as can be seen in Fig. 7, an annular axial end surface 241 of the first connection element 240 is provided with a plurality of recesses 242 arranged thereabout, optionally at equal angular intervals. Although in this example twelve recesses 242 are shown, in at least some alternative variations of this example any number of recesses greater than one can be provided, before example an odd number or an even number of recesses. For example the first connection element 240 can be provided with two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, twenty or more than twenty recesses 242, for example.

Additionally, the annular axial end surface 241 is provided with two fastening holes 244, which can be provided with an internal screw thread.

According to the second example, the respective coupler 200 comprises a first coupler element 210A and a second coupler element 210B. Furthermore, the respective coupler 200 comprises a unique engagement arrangement 212 that allows only the matched pair of the first coupler element 210A and the second coupler element 210B to be coupled to one another, and generally prevents a respective first coupler element of one such coupler to be coupled to a respective second coupler element of a different coupler.

The first coupler element 210A comprises an annular ring 211 A having the same internal and external radial dimensions as the annular axial end surface 241 of the first connection element 240. The annular ring 211 A is provided with two countersunk fastening holes 214A configured to align with the fastening holes 244 of the first connection element 240. Additionally, two countersunk screws 216A are provided for affixing the annular ring 211 A of the first coupler element 210A to the annular axial end surface 241 of the first connection element 240 via the countersunk fastening holes 214A and the fastening holes 244.

The first coupler element 210A further comprises a first portion 212A of the engagement arrangement 212, which at least in this example is in the form of a bore 212A. In at least this example, the bore is configured to align with one of the recesses 242 when the annular ring 211 A of the first coupler element 210A is connected to the axial end surface 241 of the first connection element 240, while in the same position, the remainder of the annular ring 211 A is configured to cover, conceal and seal off the remainder of the recesses 242

Although in at least this example, a plurality of recesses 242, are provided, in at least some alternative variations of this example, one or more circumferentially extending slots can be provided, which can allow more flexibility in the geometrical configuration which can be provided.

In at least some examples, the first coupler element 210A, in particular the annular ring 211 A, has an axial thickness greater than or equal to a length of the protrusion or pin 212B, and there is no need for any recesses 242 or slots in the annular axial end surface 241 of the first connection element 240; thus, such recesses 242 can be omitted in such examples.

Although in at least this example, two screws 216A are provided to connect the first coupler element 210A to the annular axial end surface 241 of the first connection element 240in at least some alternative variations of this example, more than two screws can be used, for example three or four screws, or more than four screws.

Additionally or alternatively, in at least some examples, only a single screw can be used in examples wherein the first connection element 240 is provided with a shaped recess for receipt of the annular ring 211A of the first coupler element 210A in such a way so as to restrict relative movement between the first connection element 240 and the annular ring 211 A of the first coupler element 210A in at least one degree of freedom. With reference to Fig. 8, the second connection element 260 is provided in an annular recessed internal portion thereof 262 with two fastening arrangements (not shown), which can have a female screw thread arrangement configured to receive a screw.

A second coupler element 210B comprises an annular ring 21 IB configured to fit inside the annular recessed internal portion 262 of the second connection element 260. The annular ring 21 IB is provided with two countersunk fastening holes 214B configured to align with the fastening arrangements of the second connection element 260. Additionally, two countersunk screws 216B are provided for connecting the annular ring 21 IB of the second coupler element 210B, at least partially within the annular recessed internal portion 262 of the second connection element 260, to the fastening arrangements via the countersunk fastening holes 214B.

The second coupler element 210B further comprises a second portion 212B of the engagement arrangement 212, which at least in this example is in the form of a protrusion or pin 212B that is configured to align with bore 212A when the second coupler element 210A connected to the second connection element is brought into engagement with the first coupler element 210B when connected to the first connection element. The pin 212B is arranged to project in a direction parallel to an axis of the annular ring 21 IB starting at an axial end surface 218B of the annular ring 21 IB.

The pin 212B can have any suitable cross-section that enables receipt of the pin within the bore 212A, including circular, non-circular, axisymmetric or non- axisymmetric.

In at least this example, the pin 212B has a cross-section that is complementary to the cross-section of the bore 212A.

Although in at least this example only a single pin 212B and bore 212A are provided, in at least some alternative variations of this example any number of pins and bores can be provided, as long as their relative angular positioning matches, conforms, corresponds or is aligned thereby permitting the connection elements to be brought into the engaged configuration, in which the first and second connection elements 240, 260 are coaxially aligned so as to have a common connector axis CCA, and in which the first and second connection elements 240, 260 are fully mated with one another so as to permit electrical connection therebetween.

Since in at least this example, the two parts of the engagement arrangement 212, in the form of the pin 212B and bore 212A, are located at coincident angular locations about the respective axes LCA2, LCA1 when connected to the respective connection elements 260, 240, when the first coupler element 210A and the second coupler element 210B are brought together coaxially, with respective axial end surfaces 218A, 218B of the first and second coupling elements respectively facing each other, the pin 212B is arranged to slide into, or be received in, the respective bore 212A and subsequently the respective recess 242.

However, if non-matching coupler elements 210A, 210B are brought towards one another, where the angular arrangement of the pin(s) 212B and bore(s) 212A do not match and/or the cross-sectional profiles of each of the pin(s) are not complementary to the respective cross-sectional profiles of respective bore(s), when connected to the respective connection elements 240, 260 and when the electrical pins of the connection elements 240, 260 are aligned in a manner permitting contact therebetween when pushed together along the common connection axis CCA, the pin(s) 212B will not coincide with the bore(s) 212A and instead will collide with the axial end surface 218A of the annular ring 211 A of the first coupler element 210A. This will limit the proximity of the mis-matched respective coupler elements 210A, 210B, and prevent, the mis-matched respective coupler elements 210A, 210B from being brought together to be fully coupled, and hence when mis-matched respective coupler elements 210A, 210B are connected to the wrong combination of first and second connection elements 240, 260, will prevent the wrong combination of first and second connection elements 240, 260 from being brought into the connected configuration. Accordingly, two connection elements which are provided with (and thus “coded” with) non-matching coupler elements, i.e., with non-matching geometrical configurations physically cannot be fully connected to one-another, thereby preventing errors and accidental misconnection between the first connection element of one circular connector and the second connection element of a different circular connector. Accordingly, when the properly matched first coupler element 210A and the second coupler element 210B are connected to the first connection element 240 and the second connection element 260, respectively, the engagement arrangement 212, which in this example comprises the pin(s) 212B and bore(s) 212A, is configured to permit axial translation of the respective and properly matched first and second connection elements 240, 260 along the common connector axis CCA into the connected configuration, conditional on at least the following conditions for engagement being fulfilled: a) the first geometrical configuration, or bore(s) 212A, is complementary to, matches or corresponds to the second geometrical configuration, or pin(s) 212B at least in an axial direction parallel with common connector axis CCA, so as to fit together when brought together in an axial direction along the common connector axis CCA; b) the first connection element 240 and the second connection element 260 are coaxially aligned along the common connector axis CCA; and c) the first and second portions of the engagement arrangement 212A, 212B are in an engaging enabling position, in which they are oriented about the common connector axis CCA at corresponding angular orientations so as to fit together when brought together in an axial direction along the common connector axis.

The engagement arrangement essentially acts as a limiter preventing the connection elements 240, 260 when connected to the coupler elements 210A, 210B from being brought into the connected configuration unless the conditions for engagement are fulfilled.

Alternatively or additionally, although in this example, the physical limit provided by the geometrical configurations is determined by the angular locations of the pin(s) and bore(s), it is envisaged that the limit can additionally or alternative also be provided by a non-matching size or cross-sectional profile, of a respective pin or bore.

Alternatively or additionally, although in this example, the bore is provided on the first coupler element 210A and the pin is provided on the second coupler element 210B, it is envisaged that these can be provided in the opposite manner, or alternatively, a combination of bores and pins could be provided on each of the coupler elements 210A, 210B, in conjunction with respective modifications being made to the respective connection elements as necessary. For example, but without limitation, provision of recesses for at least partial receipt of an end of the pin. Since the coupler elements 210A, 210B are each connected to the respective connection element by means of fasteners such as screws 216A, 216B, relative movement is constrained with respect to the respective connection element 240, 260 in: an axial direction along the respective central longitudinal axis; a circumferential direction about the respective central longitudinal axis; and a radial direction from the respective central longitudinal axis.

As can be seen in at least this example, the pin 212B can taper at a distal end thereof, in order to provide ease of connection between the pin 212B and bore 212A when initially pushing the connection elements 240, 260 together due to an initial clearance fit therebetween, and subsequent snug connection when in an engaged configuration due to an interference or other close fit between a less tapered or wider portion of the pin 212B and the bore 212 A.

Exemplary circular connectors in conjunction with which the second exemplary coupler could be used include, but are not limited to, any one of a MIL-DTL-38999 circular connector, a micro miniature D38999 circular connector or any other suitable mating by turn connector.

According to an aspect of the presently disclosed subject matter, there is provided a kit of couplers according to the second example thereof, wherein each coupler 200 in the kit has a respective engagement arrangement 212 that is different from the respective engagement arrangement 212 of the other couplers 200 in the kit. This allows only the matched pair of the first coupler element and the second coupler element of the respective coupler to be coupled to one another, and generally prevents a respective first coupler element of one such coupler 200 to be coupled to a respective second coupler element of a different coupler 200 in the kit.

Thus in at least some examples, a kit of couplers 200 as described above can be provided, comprising a plurality of matching pairs of coded rings with recesses and protrusions, such that at least two of these pairs are non-matching. In this way, a user can selectively code each standard pair of connection elements using differently coded couplers (e.g., having a recess(es) or a protrusion(s) or pin(s) at different angular locations).

Optionally, matching pairs of coupler elements can be colour coded in the same colour, but different from the colour of the colour code of the other coupler elements having different geometrical configurations.

Referring to Figs. 9, 10 and 11, a coupler 300 according to a third example of the presently disclosed subject matter, is similar to the second example of the coupler 200 as disclosed herein, mutatis mutandis, except for the differences described below.

According to the third example, the respective coupler 300 comprises a first coupler element 331 A and a second coupler element 31 IB. Furthermore, the respective coupler 300 comprises a unique engagement arrangement 312 that allows only the matched pair of the first coupler element 331 A and the second coupler element 31 IB to be coupled to one another, and generally prevents a respective first coupler element of one such coupler to be coupled to a respective second coupler element of a different coupler.

In at least this example, and as will become clearer below, the engagement arrangement 312, comprises a pin 312B and hole 332A (of a nut 330A). Referring to Fig. 9, the first coupler element 331A comprises a nut 330A and a first annular ring 310A. The nut 330A comprises a non-symmetrical recess or non-cylindrical shaped hole 332A passing therethrough. The nut 330A comprises an outer polygonal shape, configured to be received within a recess 313A provided in the first annular ring 310A.

The recess 313A is also polygonal and complementarily shaped with respect to the nut 330A. Furthermore, the polygonal shapes of the nut 330A and recess 313A have at least two lines of symmetry, and thus the nut 330A can be received in the recess 313A in at least two different orientations. In the illustrated example of Fig. 9 the nut 330A and recess 313A have eight lines of symmetry and thus the nut 330A can be received in the recess 313A in any one of eight different orientations. In at least some alternative variations of this example, the respective nut and the respective recess have three, four, five, six, seven, nine or more than nine lines of symmetry and thus the nut can be received in the recess in respectively any one of three, four, five, six, seven, nine or more than nine different orientations.

The first annular ring 310A can be provided as a separate component connected to an annular axial end surface of a first connection element of a circular connector, similar to axial end surface 241 of the first connection element 240, mutatis mutandis, or can constitute or be part of the axial end surface itself comprising the recess 313A. The recess 313A comprises a seat for receipt of the nut330A, which seat has an axisymmetric bore 312A continuing in a depth direction, configured to be aligned with the non- cylindrical or non-symmetrical shaped hole 332A of the nut 330A.

In contrast with the outer polygonal shape of the nut 330A, the hole 332A is non- symmetrical, as disclosed above. In at least this example the hole 332A has a flat wall part 339A joined to a concave cylindrical wall part 338A. The flat wall part 339A is at a fixed spatial relationship with respect to the outer polygonal shape of the nut 330A. On the other hand, in view of the multiple lines of symmetry of this polygonal shape, the relative spatial orientation of the flat wall part 339A with respect to the first annular ring 310A (and in at least this example, with respect to the first coupler element 331A) can be any one of corresponding multiple orientations. Thus, in the illustrated example, since the nut 330A can be received in any one of eight different orientations within the recess 313A, correspondingly the flat wall part 339A can be oriented in each pone of eight different positions with respect to the first annular ring 310A (and in at least this example, with respect to the first coupler element 331A). Referring again to Figs. 10 and 11, the second coupler element 310B comprises a second annular ring 318B and projection 312B (also referred to interchangeably herein as a pin or protrusion).

The second annular ring 318B is configured to fit inside an annular recessed internal portion of a second connection element in the same way as with the annular ring of the second coupler element 210B and the second connection element 260 of the second example, mutatis mutandis.

The second coupler element 310B of the third example differs from the second coupler element 210B of the second example in that the projection 312B comprises a shaft 332B having a non-symmetrical (for example, non-cylindrical) shaft cross-section.

Furthermore, the shaft cross-section is complementarily shaped with respect to the hole 332A, and has flat wall part 339B corresponding to flat wall part 339A, and a convex cylindrical wall part 338B corresponding to concave cylindrical wall part 338A.

Thus, when the projection 312B, in particular the shaft 332B, is properly oriented with respect to the hole 332A, then the projection 312B, in particular the shaft 332B, can be axially passed through the hole 332A. By "properly oriented" is meant that the flat wall part 339B and the flat wall part 339A are aligned with one another, and facing one another when the projection 312B, in particular the shaft 332B, is received in the hole 332A

However, when the projection 312B, in particular the shaft 332B, is not properly oriented with respect to the hole 332A, then the projection 312B, in particular the shaft 332B, cannot be inserted through the hole 332A.

Thus, in a matched pair of first coupler element 331A and second coupler element 310B, the projection 312B, in particular the shaft 332B, is properly oriented with respect to the hole 332A. Thus, the nut 330A is received in a desired one of the multiple possible different orientations within the recess 313A, and correspondingly the nut 330A is oriented with respect to the first annular ring 310A (and in at least this example, with respect to the first coupler element 331 A). Similarly, projection 312B, in particular the shaft 332B is oriented in a matching manner with respect to the second annular ring 318B (and in at least this example, with respect to the second coupler element 31 IB). Thus, in use, a user can independently choose for each pair of connection elements of a circular connector the orientation of each of the non-cylindrical pin 312B and nut 330A, such that they are configured to match, conform or complement one another on each pair of connection elements, but do not match one another between connection elements from different pairs of connection elements.

Since in this example, the pin 312B and hole 332A of the nut 330A are located at coincident angular locations about the respective axes LCA2, LCA1 when connected to the respective connection elements, when the two connection elements in a pair are brought together coaxially, with the pin 312B protruding towards the nut 330A, the pin 312B is arranged to slide into, or be received in, the non-cylindrical c shaped hole 332A of the nut 330A and subsequently the axisymmetric bore 312A.

However, if a pin 312B and nut 330A of non-matching (i.e., improper) orientation are brought towards one another when connected to the respective connection elements and when the electrical pins of the connection elements are aligned in a manner permitting contact therebetween when pushed together along the common connection axis CCA, the pin(s) 312B will collide with the nut 330A and not pass through the hole 332A. When mis-matched coupler elements are connected to the first and second connection elements, this will limit their proximity and will prevent the first and second connection elements from being brought into the connected configuration. Accordingly, two mis-matched connection elements which are “coded” with non-matching coupler elements, i.e. nonmatching geometrical configurations physically cannot be fully connected to one-another, thereby preventing errors and accidental misconnection.

Accordingly, when the properly matched nut 330 A is connected to the first connection element and the pin 312B is connected to the second connection element, the engagement arrangement 312, which in this example comprises the pin 312B and hole 332A of the nut 330A, is configured to permit axial translation of the respective and properly matched first and second connection elements along the common connector axis CCA into the connected configuration, conditional on at least the following conditions for engagement being fulfilled: a) the first geometrical configuration, or non-cylindricalshaped hole 332A of the nut 330A, is complementary to, matches or corresponds to the second geometrical configuration, or pin 312B at least in an axial direction parallel with common connector axis CCA, so as to fit together when brought together in an axial direction along the common connector axis CCA; b) the first connection element and the second connection element are coaxially aligned along the common connector axis CCA; and c) the first and second portions of the engagement arrangement 332A, 312B are in an engaging enabling position, in which they are oriented about the common connector axis CCA at corresponding angular orientations so as to fit together when brought together in an axial direction along the common connector axis.

The engagement arrangement essentially acts as a limiter preventing the connection elements when connected to the coupler elements 330A, 310B from being brought into the connected configuration unless the conditions for engagement are fulfilled.

Alternatively or additionally, although in this example, the physical limit provided by the geometrical configurations is determined by the particular orientation of the pin and bore, it is envisaged that the limit can additionally or alternative also be provided by a non-matching size or cross-sectional profile, of a respective pin or bore.

While in this example, the nut 330A is octagonal allowing eight different orientations of the nut and respective pin 312B, it is envisaged that the nut could have any polygonal shape capable of having rotational symmetry of order at least two.

Alternatively or additionally, although in this example, the nut 330A is arranged to be received on the first connection element and the pin is provided on the second coupler element 310B, it is envisaged that these can be provided in the opposite manner, or alternatively, a combination of bores and pins could be provided on each of the coupler element, in conjunction with respective modifications being made to the respective connection elements as necessary.

Since the nut 330A and pin 312B are configured to be operably mounted to the respective connection elements such that relative movement is constrained with respect to the respective connection elements in: an axial direction along the respective central longitudinal axis; a circumferential direction about the respective central longitudinal axis; and a radial direction from the respective central longitudinal axis.

Examples of circular connectors in conjunction with which the third exemplary coupler can be used, include, but are not limited to, any one of a MIL-DTL-38999 circular connector, a micro miniature D38999 circular connector or any other suitable mating by turn connector.

Although in at least this example, only a single protrusion 312B and nut 330A are provided, in at least some alternative variations of this example, there can be provided more than one nut 330A and more than one protrusion 312B, such as two or more of each, configured to be located at predetermined relative angular locations about the longitudinal central axes of the respective first and second connection elements configured to correspond with one another.

While in at least this example the projection 312B, in particular the shaft 332B, and the hole 332A each have a respective flat wall part to provide the respective nonsymmetry, in at least some alternative variations of this example the respective projection, in particular the respective shaft, and the respective hole can have any suitable non- symmetric profile.

According to an aspect of the presently disclosed subject matter, there is provided a kit of couplers according to the third example thereof, wherein each coupler 300 in the kit has a respective engagement arrangement 312 that is different from the respective engagement arrangement 312 of the other couplers 300 in the kit. This allows only the matched pair of the first coupler element and the second coupler element of the respective coupler to be coupled to one another, and generally prevents a respective first coupler element of one such coupler 300 to be coupled to a respective second coupler element of a different coupler 300 in the kit.

Thus in at least some examples, a kit of different-coded said couplers 300 as described above for the third example can be provided, comprising a plurality of non- cylindrical or non-axisymmetrical pins or protrusions and a plurality of nuts having non- cylindrical or non-axisymmetrical through-holes.

Optionally, the kit could also include any necessary rings or fastenings as required.

Optionally, indicia or markings could be provided on an outer surface of the coupler elements to aid a user in aligning these when making the electrical connections.

Referring to Figs. 12A and 12B, a circular connector 420 (also referred to interchangeably herein as a cylindrical connector) according to a third example of the presently disclosed subject matter, comprises a first generally cylindrical connection element 440 and a second generally cylindrical connection element 460.

As shown in Fig. 12A, the first connector element 440 is similar to first connector element 40 described above, mutatis mutandis, and comprises a hollow housing portion 441 surrounding a central void 444. The central void 444 is arranged to receive a one or more electrical connection elements 443, which can be male, female or a combination of male and female, for example, a set of pins, recesses or similar arrangements. Once the electrical connection elements 443 are received centrally within the central void 444, there is an annular space around the electrical connection elements 443, arranged to receive therein a first coupler element 410A.

The respective coupler 400 according to the fourth example of the presently disclosed subject matter comprises a first coupler element 410A and a second coupler element 410B. Furthermore, the respective coupler 400 comprises a unique engagement arrangement 412 that allows only the matched pair of the first coupler element 410A and the second coupler element 410B to be coupled to one another, and generally prevents a respective first coupler element of one such coupler to be coupled to a respective second coupler element of a different coupler.

The fourth example can be of particular use where the number of pins/sockets of the electrical connection arrangement is small. Alternatively, a circular connecter having a relatively large internal diameter and generally used for a large number of pins/sockets can be used with a relatively smaller number of pins/sockets when implementing the third example. In at least this example, the first coupler element 410A comprises a central longitudinal axis AA and has a hollow cylindrical shape designed to allow passage of the electrical connection elements 443 at least partially therethrough. At one end, the first coupler element 410A comprises an annular flange 414A, comprising a plurality of boreholes 420A passing through a thickness thereof. The first coupler element 410A can be fixed within the annular recess surrounding the electrical connection elements 443 within the central void 444 via fasteners such as for example screws 422A passing through the boreholes 420A of the flange 414A and into the housing portion 441 of the first connector element 440.

The first coupler element 410A, in particular the engagement arrangement 412, comprises a first geometrical configuration, in the form of one or more grooves 412A arranged at select angular locations around, and recessed into, an inner circumferential surface of the hollow cylindrically shaped first coupler element 410A. These grooves 412A extend in a direction parallel to the central longitudinal axis AA of the first coupler element 410A.

As shown in Fig. 12B, the second connector element 460 is similar to second connector element 60 described above, mutatis mutandis, and comprises a hollow housing portion 461 surrounding a central void 464. The hollow housing portion 461 comprises a locking ring 462 with a textured surface to enable a user to easily grip the second connector element 460 and apply a twisting force or torque to permit changing between the connected configuration and the disconnected configuration of the connection elements 440, 460. The central void 464 is arranged to receive a one or more electrical connection elements 463, which can be male, female or a combination of male and female. For example, a set of pins, recesses or similar. Once the electrical connection elements 463 are received centrally within the central void 464, there is an annular space around the electrical connection elements 463, arranged to receive therein a second coupler element 41 OB.

In at least this example, the second coupler element 410B comprises a central longitudinal axis BB and has a hollow cylindrical shape designed to allow passage of the electrical connection elements 463 at least partially therethrough. At one end, the second coupler element 410B comprises an annular flange 414B, comprising a plurality of boreholes 420B passing through a thickness thereof. The second coupler element 410B can be fixed within the annular recess surrounding the electrical connection elements 463 within the central void 463 by means of fasteners such as screws 422B passing through the boreholes 420B of the flange 414B and into the housing portion 461 of the second connector element 460.

The second coupler element 410B, in particular the engagement arrangement 412, further comprises a second geometrical configuration, in the form of one or more radially outwardly protruding keys 412B arranged at select angular locations around an outer circumferential surface of the hollow cylindrically shaped second coupler element 410B. These keys 412B extend in a direction parallel to the central longitudinal axis BB of the second coupler element 410B.

Once the first and second coupler elements 410A, 410B are fastened or fixed to the first and second connection elements 440, 460 respectively, the first and second connection elements 440, 460 can be brought together along a common central axis in the manner described in the examples above, mutatis mutandis, such that the keys 412B are aligned with the grooves 412A and are at least partially received therein. Thus, the coupler elements 410A, 410B and the connection elements 440, 460 must be coaxially aligned about a common central axis CCA, and rotationally oriented about that common central axis CCA in a manner such that the keys and grooves are aligned. Furthermore, the particular first and second geometrical arrangements, i.e. the keys and grooves 412B, 412A, must match or be compatible, for example, but without limitation, in terms of number, size and angular arrangement of the keys and grooves 412B, 412A.

Although in this example, screws are shown as the fastening arrangement for fixing the first and second coupler elements 410A, 410B to the first and second connection elements 440, 460 respectively, in at least some alternative variations of this example, any suitable fastening or fixing arrangement known to the skilled person could be used alternatively.

Although in at least this example, keyways or grooves are provided on the first coupler element and keys are provided on the second coupler element, in at least some alternative variations of this example, the grooves and keys can be provided on the opposite components, and/or each of the first and second coupler elements can comprise at least one groove and at least one key, as long as the geometrical configurations are compatible with one another.

Additionally or alternatively, the keys need not extend longitudinally, and can simply comprise a protrusion which travels along the groove as the first and second coupler elements are brought between the connected and disconnected configurations.

Referring to Fig. 13, according to another aspect of the presently disclosed subject matter, a kit 500 is provided, comprising a plurality of first coupler elements 510_a, 510b, ..., 510N, where the plurality is an integer N. The kit further comprises a plurality of second coupler elements 520_a, 520b, ..., 520N, where the plurality is also the integer N. Thus, the kit comprises N couplers 520, each of which comprising a pair of first and second coupler elements.

The couplers 520 are couplers for a plurality of circular connectors, each circular connector comprising a first generally cylindrical connection element having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, for example as disclosed herein mutatis mutandis. The first connection element and the second connection element have a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween. The first connection element and the second connection element also have a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another.

As disclosed above, each coupler 520 comprises a respective first coupler element and a second coupler element. Each first coupler element is connectable to a respective first connection element, and comprises a first portion of a respective engagement arrangement, which first portion comprises a first geometrical configuration. Each respective second coupler element is connectable to a respective second connection element, and comprises a respective second portion of the engagement arrangement, the second portion comprising a second geometrical configuration.

When the respective first coupler element and the respective second coupler element of one of the couplers are connected to the first connection element and the second connection element respectively of a circular connector, the respective engagement arrangement is configured to permit axial translation of the first and second connection elements along the common connector axis into the connected configuration, conditional on at least the following conditions for engagement being fulfilled: a) the first geometrical configuration is complementary to, matches or corresponds to the second geometrical configuration at least in an axial direction parallel with common connector axis, so as to fit together when brought together in an axial direction along the common connector axis; b) the first connection element and the second connection element are coaxially aligned along the common connector axis; and c) the first and second portions of the engagement arrangement are in an engaging enabling position, in which they are oriented about the common connector axis at corresponding angular orientations so as to fit together when brought together in an axial direction along the common connector axis.

At least one of the first coupler elements in the kit 500 has a first geometrical configuration which is incompatible with at least one, and optionally all the other, of the second geometrical configurations of the second coupler elements in the kit.

The kit can comprise two or more couplers, such as 2, 3, 4, 5, 6, 7, 8, 9 or 10 couplers or more than ten couplers, for example.

Optionally each of the couplers within the kit 500 can have unique geometrical configurations, such that the respective first coupler elements and the respective second coupler element have only a single unique one-to-one correspondence in terms of compatibility.

Optionally each of the first coupler element within the kit is geometrically compatible with only one second coupler element within the kit. Alternatively or additionally, each of the second coupler element within the kit are geometrically compatible with only one first coupler element within the kit.

The couplers in the kit or in any of the examples described above can, for example, be produced using additive manufacture, for example, by 3D printing. Materials which can be deposited include, but are not limited to, polymer material such as a plastic, metal material such as aluminium, stainless steel or titanium, composite materials (for example fiber reinforced materials) or any other material suitable for additive manufacture as known to the skilled person. Optionally, matching pairs of coupler elements could be colour coded in the same colour, but different from coupler elements having different or incompatible geometrical configurations.

It should be noted that the word “comprising” as used throughout the appended claims is to be interpreted to mean “including but not limited to”.

While there has been shown and disclosed examples in accordance with the presently disclosed subject matter, it will be appreciated that many changes can be made therein without departing from the scope of the presently disclosed subject matter as set out in the claims.

Claims

CLAIMS:

1. A coupler for a circular connector, the circular connector comprising a first generally cylindrical connection element having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; the coupler comprising: a first coupler element connectable to the first connection element, the first coupler element comprising a first portion of an engagement arrangement, the first portion comprising a first geometrical configuration; and a second coupler element connectable to the second connection element, the second coupler element comprising a second portion of the engagement arrangement, the second portion comprising a second geometrical configuration; and wherein, when the first coupler element and the second coupler element are connected to the first connection element and the second connection element, respectively, the engagement arrangement is configured to permit axial translation of the first and second connection elements along the common connector axis into the connected configuration, conditional on at least the following conditions for engagement being fulfilled:

(a) the first geometrical configuration is complementary to, matches or corresponds to the second geometrical configuration at least in an axial direction parallel with common connector axis, so as to fit together when brought together in an axial direction along the common connector axis; an

(b) the first connection element and the second connection element are coaxially aligned along the common connector axis; and (c) the first and second portions of the engagement arrangement are in an engaging enabling position, in which they are oriented about the common connector axis at corresponding angular orientations so as to fit together when brought together in an axial direction along the common connector axis.

2. The coupler according to claim 1, wherein each of the first and second coupler elements, when connected to the respective first and second connection element, is constrained with respect to the respective connection element at least: to prevent relative movement in an axial direction along the respective central longitudinal axis; and to prevent relative movement in a radial direction from the respective central longitudinal axis.

3. The coupler according to claim 1 or 2, wherein the engagement arrangement acts as a limiter preventing the connection elements when connected to the coupler elements from being brought into the connected configuration unless the conditions for engagement are fulfilled.

4. The coupler according to any one of claims 1 to 3, wherein at least one of the first and second portions of the engagement arrangement comprises at least one projection and at least the other of the first and second portions of the engagement arrangement comprises a corresponding at least one recess; configured to receive the at least one projection; wherein, in use, when the coupler elements are connected to the respective connection elements:

5. The coupler according to any one of claims 1 to 4, wherein the first and second coupler elements are configured to be mounted to a cylindrical outer surface of the respective first and second connection elements.

6. The coupler according to claim 5, wherein each of the first and second coupler elements comprises a hollow annular body comprising a central longitudinal axis.

7. The coupler according to claim 6, wherein the hollow annular body comprises at least two arc-shaped members; and wherein the arc-shaped member are connected in a hinged manner at one end and configured with a snap-fit closure at the other.

8. The coupler according to claim 6, wherein the hollow annular body comprises at least two arc-shaped members; and wherein the two arc-shaped member are configured at both ends with snap-fit closures.

9. The coupler according to any one of claims 1 to 4, wherein the first coupler element comprises a first annular plate configured to be mounted to an axial end surface of the first connection element; and wherein the second coupler element comprises a second annular plate configured to be mounted to the second connection element; wherein the first annular plate comprises at least one through-bore passing through a thickness of said plate, and the second annular plate is provided with at least one protrusion configured to extend orthogonal to a surface of said second annular plate; wherein, when the conditions for engagement are fulfilled, the first and second annular plates can be brought together, such that the at least one protrusion is configured to be at least partially received in the at least one through-bore.

10. The coupler according to claim 9, wherein the at least one protrusion is configured to taper in a direction away from said second annular plate.

11. The coupler according to claim 9 or 10, wherein the at least one through-bore comprises at least two through-bores located at predetermined relative angular locations about a central axis of said first annular plate, and wherein the at least one protrusion comprises at least two protrusions configured to be located at predetermined relative angular locations about a central axis of said second annular plate configured to correspond with the predetermined relative angular locations of the at least two through-bores.

12. The coupler according to any one of claims 1 to 4, wherein the first coupler element comprises at least one non-rotationally symmetric recess extending therein when viewed along an axis of the at least one recess; and wherein the second coupler element comprises at least one protrusion configured to be mounted to the second connection element, the at least one protrusion configured to extend parallel to an axis of the second connection element, wherein the at least one protrusion comprises a non-rotationally symmetric cross-section taken orthogonal to an axis of the protrusion; wherein, when the conditions for engagement are fulfilled, the at least one protrusion can be passed at least partially through the at least one recess.

13. The coupler according to claim 12, wherein the at least one protrusion is configured to taper along the axis thereof.

14. The coupler according to any one of claims 12 to 13, wherein the at least one non- symmetrical recess comprises at least two non-symmetric recesses configured to be located at predetermined relative angular locations about the first longitudinal central axis of the first connection element, and wherein the at least one protrusion comprises at least two protrusions configured to be located at predetermined relative angular locations about the second longitudinal central axis of the second connection element configured to correspond with the predetermined relative angular locations of the recesses configured to receive the at least two protrusions.

15. The coupler according to any one of claims 1 to 4, wherein the first coupler element has a hollow cylindrical shape and comprises a central longitudinal axis, and wherein the first geometrical configuration comprises at least one of a longitudinally extending groove or a protrusion; and wherein the second coupler element has a hollow cylindrical shape and comprises a central longitudinal axis, and wherein the second geometrical configuration comprises at least the other of the longitudinally extending groove or the protrusion; wherein, when the conditions for engagement are fulfilled, the first and second coupler elements, when fixed to the respective first and second connection elements, can be brought together, such that the protrusion is configured to be at least partially received in the groove.

16. The coupler according to claim 15, wherein the protrusion comprises a key extending longitudinally along the respective coupler element.

17. The coupler according to any one of claims 15 to 16, wherein each of the first and second coupler elements further comprises a flange configured to facilitate fixing of the respective first and second coupler element within the respective first or second connection element.

18. The coupler according to any one of claims 15 to 17, wherein each of the first and second coupler elements comprises a plurality of protrusions or grooves located at predetermined angular locations about the respective central axis.

19. The coupler according to any one of claims 1 to 18, wherein at least a portion of the coupler is made from at least one of

- a polymer material, optionally a plastics material; and

- a metal, optionally any one of steel, aluminium or titanium;

- a composite materials, optionally a fiber reinforced materials.

20. The coupler according to any one of claims 1 to 19, wherein the coupler is configured to be retrofitted on a pre-existing circular connector.

21. The coupler according to any one of claims 1 to 20, being a coupler is suitable for use with any one of a MIL-DTL-38999 circular connector, a micro miniature D38999 circular connector or any other suitable mating by turn connector.

22. A circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is operatively connected with a coupler as defined in any one of claims 1 to 21.

23. A circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler according to any one of claims 5 to 8; wherein the first coupler element is externally affixed with respect to the first connection element, and wherein the second coupler element is externally affixed with respect to the second connection element.

24. A circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler according to any one of claims 9 to 11; wherein the first connection element comprises an annular axial end surface comprising a plurality of bores, the annular axial end surface being configured to receive thereon the first annular plate; and wherein the second connection element is configured to receive the second annular plate.

25. The circular connector according to claim 24, wherein the plurality of bores comprises a plurality of blind-bores.

26. The circular connector according to claim 24, wherein the plurality of bores comprises a plurality of through-bores.

27. A circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler according to any one of claims 12 to 14; wherein the first connection element comprises an axial end surface configured to receive the first coupler element; and wherein the second connection element is configured to receive the second coupler element.

28. A circular connector comprising a first generally cylindrical connection element each having a first longitudinal central axis, and a second generally cylindrical connection element having a second longitudinal central axis, the first connection element and the second connection element having: a connected configuration in which the first and second connection elements are coaxially aligned so as to have a common connector axis, and in which the first and second connection elements are fully mated with one another so as to permit electrical connection therebetween; and a disconnected configuration in which the first and second connection elements are not full mated with one another and are electrically disconnected from one another; wherein the circular connector is configured to receive the coupler according to any one of claims 15 to 18; wherein the first connection element comprises a first annular space around one or more electrical connection elements, the first annular space being configured for receiving the first coupler element; and wherein the second connection element comprises a second annular space around one or more electrical connection elements, the second annular space being configured for receiving the second coupler element.

29. The circular connector according to any one of claims 22 to 28, comprising any one of a MIL-DTL-38999 circular connector, a micro miniature D38999 circular connector or any other suitable mating by turn connector.

30. A kit comprising a plurality of couplers, wherein each coupler is as defined in any one of claims 1 to 21, wherein the first portion of the engagement arrangement of one of the plurality of couplers is incompatible with the second portion of the engagement arrangement of at least one other coupler of the plurality of couplers.

31. A kit comprising a plurality of couplers, wherein each coupler is as defined in any one of claims 1 to 21, wherein the first geometrical form of the first portion of the engagement arrangement of one of the plurality of couplers is incompatible with the second geometrical form of the second portion of the engagement arrangement of at least one other coupler of the plurality of couplers.

32. A kit according to any one of claims 30 to 31, wherein a colour of the first coupling element of one of the plurality of couplers does not match a colour of the second coupling element of at least one other coupler of the plurality of couplers.

33. A kit comprising a plurality of circular connectors as defined in claim 23 and a plurality of couplers as defined in any one of claims 5 to 8.

34. A kit comprising a plurality of circular connectors as defined in any one of claims 24 to 26 and a plurality of couplers as defined in any one of claims 9 to 11; wherein, in use, the first annular plate is mounted to the first connection element such that the at least one through-bore of the annular plate is selectively aligned with a respective at least one bore of the plurality of bores in the respective connection elements; and wherein, in use, the at least one protrusion of the second annular plate is selectively mounted thereon, so as to extend orthogonally therefrom, at angular locations around the second annular plate corresponding to the at least one through-bore.

35. A kit comprising a plurality of circular connectors as defined in claim 27 and a plurality of couplers as defined in any one of claims 12 to 14; wherein, in use, the first coupler element comprising the non-symmetrical recess is fixed to the first connection element at a rotational orientation selected by the user; and wherein, in use, the at least one non-symmetrical protrusion is selectively fixed to the second connection element at a rotational orientation selected by the user, so as to correspond with the rotational orientation of the at least one recess selected by the user.

36. A kit comprising a plurality of circular connectors as defined in any one of claim 27 to 28 and a plurality of couplers as defined in any one of claims 15 to 18.