EP3842187B1 - Device for connecting a power cable - Google Patents

Description

The invention relates to a device for connecting a power cable to an electronic unit of a power tool, with at least one clamping device for clamping a connecting line of the power cable, according to the type defined in more detail in the preamble of claim 1. Furthermore, the invention relates to a power tool.

A generic device is known from EN 10 2006 022 996 A1 known.

The EP 2 875 909 A1 describes a support device for an electrically driven garden tool with a base plate to which the garden tool can be attached, a receiving container unit in which the garden tool can be arranged and a sealing unit to seal the receiving container unit in a watertight manner.

From the EP 3 225 362 A1 A motor control unit for controlling an electronically driven hand tool is known.

The US 2018/233006 A1 describes a plug adapter for the theft protection of an electrical device connected to the plug adapter via its mains plug.

A in the US 2005/085124 A1 The power tool described comprises a housing in which at least one of the motor, electronics and drive gear is arranged, a conductor channel with at least one flexible section and one rigid section and at least one stranded conductor which is arranged in a receptacle of the conductor channel.

The EP 1 175 286 A1 relates to a hand-held power tool with a shell-shaped housing with a socket for a power cable.

EN 10 2016 116 563 A1 describes a housing element for accommodating an electrical component, with a first housing element part and a second housing element part movable relative thereto.

The DE 20 2016 106 821 U1 describes a mains connection system for a power tool which has a plug connection with a device socket and a device plug so that in the event of a defect in a power cable it can be easily replaced.

From the EN 10 2005 000 162 A1 A mains-operated hand tool with a housing from which a mains cable extends to a power connection is known. An assembly opening in the housing is provided which can be closed by an assembly cover and through which connecting means and fixing means can be moved from the inside of the housing. The connecting means can be used to electrically connect the cable-side strands of the mains cable to the device-side strands of a device's wiring.

In the EN 100 05 989 A1 describes a hand-held power tool which has a service cover in the area of the outlet opening of a power cable on a housing, which is dimensioned such that the power cable can be removed after opening it.

The EP 2 384 855 B1 describes an angle grinder with a housing in which a motor and a switching block having a switch and a control for controlling the motor are arranged.

From the EP 2 228 179 B1 A hand-held power tool with a motor housing and a motor housed within the motor housing is known.

An electric hand-held power tool with a switch having a coupling for detachable mechanical and simultaneous electrical contact with an electronic module is in the EN 10 2004 051 653 A1 described.

When using power tools equipped with such power cables or with such devices for connecting the power cable to the electronic unit, the power cable may be damaged due to carelessness, for example, and must then be replaced by a qualified service technician. Such a replacement or change of the power cable should be as simple as possible and require as few tools and spare parts as possible. It should also be ensured that replacing the power cable does not impair the dust resistance of the power tool. The solutions described above do offer approaches to this, but they do not provide a satisfactory solution in practice.

It is therefore an object of the present invention to provide a device for connecting a power cable to an electronic unit of a power tool, which enables a simple replacement of a power cable without negatively affecting the basic properties of the power tool.

According to the invention, this object is achieved by the features mentioned in claim 1.

The connecting element according to the invention creates a connection between the clamping device and the contact device and thus ultimately between the connecting cable and the electronic unit, which results in simple and secure contact. The connecting element runs through an opening in a housing element that spatially separates the clamping device from the electronic unit. The term "spatially separating" means that the housing element is located between the clamping device used to clamp the connecting cable of the power cable and the electronic unit, so that the clamping device and the electronic unit are located in two different areas or spaces within a housing. The sealing device supports this spatial separation between the clamping device and the electronic unit by sealing the opening for the connection element to pass through.

The housing element, in conjunction with the sealing device, therefore shields the electronic unit and the part of the contact device that is located in the area of the electronic unit from the clamping device, so that dust or other contaminants that may be in the area of the electronic unit cannot get into the area of the clamping device. In this way, the service person changing the power cable does not have access to the electronic unit, so that no damage or other negative influences on the electronic unit can occur when the power cable is replaced.

In particular, but not exclusively, the device according to the invention is suitable for power tools that are driven by a brushless electric motor, since changing the power cable is the most common servicing case for such power tools.

Because the opening is sealed by means of a sealing device attached to the connecting element, the penetration of dirt from the area in which the electronic unit is located into the area in which the connecting cable is located is reliably prevented.

A very simple and cost-effective design of the sealing device is obtained if it is formed in one piece with the housing element and has a considerably smaller wall thickness than the housing element.

If, in a further advantageous embodiment of the invention, the sealing device is designed as a sealing lip surrounding the opening of the housing element, a very simple and cost-effective but nevertheless reliable seal between the clamping device and the electronic unit is ensured.

In order to better separate the area in which the power cable is exchanged or changed from the other areas of the power tool, in particular from the electronics unit, it can further be provided that the housing element is designed, at least in sections, as the floor of a power cable exchange space.

If the power cable changing compartment can be closed by means of a removable cover, this provides very good encapsulation of the area in which the power cable is connected and, on the other hand, allows very easy access to this power cable changing compartment by removing the cover.

The sealing of the power cable replacement space can be improved if the cover can be sealed against the housing element by means of a tongue and groove connection.

In a further advantageous embodiment of the invention, a strain relief device can be provided with which a sheath of the power cable can be clamped. Such a strain relief device ensures that when a tensile force is applied to the power cable, no or only a very small force is applied to the connecting cable, so that its connection to the clamping device remains guaranteed.

A very reliable contact between the connecting cable and the electronic unit via the clamping device and the contact device is achieved if the contact device has a metallic contact element.

Furthermore, it can be provided that two connecting elements with respective clamping devices and respective contact devices are provided. This embodiment is advantageous for most common power tools.

Claim 10 specifies a power tool with a power cable, with an electronic unit and with a device according to the invention for connecting the power cable to the electronic unit.

In addition, it should be noted that terms such as "comprising," "having," or "having" do not exclude other features or steps. Furthermore, terms such as "a," "an," or "the," which refer to a singular number of steps or features, do not exclude a plurality of features or steps, and vice versa.

Further features and advantages of the invention emerge from the following description of an embodiment of the invention. The figures show several features of the invention in combination with one another. Of course, the person skilled in the art can also consider these separately from one another and, if necessary, combine them to form further useful sub-combinations without having to be inventive.

Figur 1

einen Teil eines erfindungsgemäßen Elektrowerkzeugs mit einem einen Kabelwechselraum abschließenden Deckel;

Figur 2

eine Ansicht gemäß Figur 1, bei der der Deckel abgenommen ist;

Figur 3

eine Draufsicht gemäß dem Pfeil III aus Figur 2;

Figur 4

einen Schnitt nach der Linie IV-IV aus Figur 3;

Figur 5

eine vergrößerte Darstellung gemäß der Linie V aus Fig. 4 in einem ersten Zustand; und

Figur 6

die Darstellung aus Fig. 5 in einem zweiten Zustand.

They show schematically:

Figure 1

a part of a power tool according to the invention with a cover closing off a cable changing space;

Figure 2

a view according to Figure 1 with the lid removed;

Figure 3

a plan view according to arrow III Figure 2 ;

Figure 4

a section along line IV-IV Figure 3 ;

Figure 5

an enlarged view along line V of Fig.4 in a first state; and

Figure 6

the representation of Fig.5 in a second state.

Figure 1 shows a part of a power tool 1, in this case an angle grinder. The power tool 1 has a housing 2, to which a power cable 3 leads for the electrical supply of the power tool 1. The power cable 3 is Figure 1 a casing 4 located outside the housing 2 of the power tool 1 is shown. The housing 2 of the power tool 1 also has a cover 5 which is screwed to the housing 2 and can be removed from the same. Screws (not shown) are used to connect the cover 5 to the housing 2 and which are passed through through holes 6 in the cover 5.

In Figure 2 is the Figure 1 shown part of the power tool 1 without the cover 5. In addition to the housing 2 and the power cable 3, Figure 2 a power cable changing compartment 7 and a device 8 for connecting the power cable 3 to an electronic unit 9 of the power tool 1. The electronic unit 9 or a circuit board thereof is in Figure 4 shown schematically. In principle, the device 8 described below can also be used for other power tools 1, although angle grinders are usually subject to very high levels of dust during operation. The device 8 ensures that this dust does not have a negative impact on the operation of the power tool 1.

The device 8 has at least one, in the present case two clamping devices 10 for clamping respective connecting lines 11 of the power cable 3 and a contact device 12 for establishing an electrical contact between the connecting line 11 clamped by means of the clamping device 10 and the electronic unit 9. For clamping the connecting lines 11, the clamping device 10 has respective screws 13 which are inserted into threads (not shown) of the clamping device 10 engage. The contact device 12 has a metallic contact element 12a, which is in electrical contact with the connecting line 11 via the screw 13.

The clamping devices 10 and the contact devices 12 are each arranged individually on a respective connecting element 14, which runs through a respective opening 15 in a housing element 16, which separates the clamping device 10 from the contact device 12. In addition to the housing element 16 and the cover 5, the housing 2 also has a lower housing element 19, which forms the largest part of the housing 2. The connection between the housing element 16, which in this case can also be referred to as the upper housing element 16, and the lower housing element 19 can be made in a manner known per se.

The housing element 16, through whose openings 15 the two connecting elements 14 run, is designed at least in sections as the floor of the power cable changing space 7 or has a section that forms the floor of the power cable changing space 7. While in the present case the floor of the power cable changing space 7 is designed as one piece with the housing element 16, it is also conceivable in principle to design the floor separately from the housing element 16, for example in the form of an insert, and to connect it firmly to the same, e.g. via a tongue and groove connection. In this case, the floor still forms a housing element of the housing 2. In order not to make the sealing between the clamping device 10 and the electronic unit 9, which is described in more detail below, more difficult, it is advantageous to design the floor of the power cable changing space 7 as one piece with the housing element 16 or to design the housing element 16 in such a way that it forms the floor of the power cable changing space 7 at least in sections.

The housing element 16 or the floor of the power cable replacement space 7 thus separates the clamping device 10, to which the connecting lines 11 of the power cable 3 are connected, from the electronic unit 9 and from the area in which the contact device 12 is connected to the electronics unit 9. The connecting elements 14 can also be referred to as domes, since they protrude from the electronics unit 9 through the housing element 16 upwards into the power cable replacement space 7.

However, it would be fundamentally possible for dirt, dust or similar to get through the opening 15 from the area or room in which the electronic unit 9 is located into the area or room in which the clamping device 10 is located, i.e. into the power cable replacement space 7.

In order to improve the sealing between the power cable replacement space 7 and the area in which the electronic unit 9 is located, the opening 15 is sealed by means of a sealing ring 16 which is located on the connecting element 14 and Figures 5 and 6 shown sealing device 20. In the present exemplary embodiment, the sealing device 20 is formed in one piece with the housing element 16 and has a considerably smaller wall thickness than the housing element 16. In the present exemplary embodiment, the sealing device 20 is a sealing lip which runs around the opening 15 of the housing element 16, through which the connecting device 14 is guided during assembly. Such sealing lips can be injection-molded onto the housing element 16 during manufacture of the housing element 16 and thus formed in one piece with the same. This is a very reliable production of the sealing device 20. The thin material of this sealing lip is displaced by the connecting element 14 during assembly, so that the sealing device 20 rests against the connecting element 14 without a gap and seals the opening 15.

While in Figure 5 the sealing device 20 is shown in its non-loaded state, since the connecting element 14 shown in dashed lines in this case is not yet in the opening 15, in Figure 6 the deformation of the sealing device 20 by the connecting element 14 inserted into the opening 15 can be seen. The sealing device 20 rests against the connecting element 14 and thus ensures that the opening 15 is sealed. The length of the sealing device 20 into the opening 15 should therefore preferably be selected such that the connecting element 14 and the sealing device 20 adjacent to it provide a reliable seal of the opening 15.

While the Figures 5 and 6 show an embodiment of the sealing device 20 in the form of a sealing lip, other embodiments of the sealing device 20 are also possible, with which a gap-free fit of the sealing device 20 on the connecting element 14 and thus a reliable sealing of the opening 15 can be ensured.

For example, very precise tolerances in the manufacture of the housing element 16 and in particular its openings 15 and in the manufacture of the connecting element 14 can produce a certain oversize of the connecting element 14 in relation to the opening 15, so that when the connecting element 14 is inserted into the opening 15, a sealing effect is created in conjunction with the respective, preferably elastic materials of the housing element 16 and the connecting element 14, for example suitable plastic materials. Such a solution is also considered to be a sealing device 20, since it is able to seal the opening 15 in such a way that no dirt, dust or similar can get through the opening 15 from the area or room in which the electronics unit 9 is located into the power cable changing room 7.

Furthermore, it is possible to design the sealing device 20 and the housing element 16 in the form of a two-component design, in which, for example, the sealing device 20 is inserted into an injection mold with which the housing element 16 is produced. The housing element 16 can optionally have a groove into which the sealing device 20 is inserted in the form of a blank.

A further possibility is to arrange the sealing device 20 on the connecting element 14 so that the opening 15 is sealed when the connecting element 14 is inserted into it.

In order to prevent dust or dirt from outside from entering the power cable changing room 7, the cover 5 is sealed off from the housing element 16 by means of a tongue and groove connection 17. In the present case, the housing element 16 has a groove 16a into which a tongue 5a of the cover 5 engages. The cover 5 has no air slots or the like, so that no dust can penetrate into the power cable changing room 7.

In the power cable replacement space 7, a strain relief device 18 is also provided, which has a clamp 18a for clamping the sheath 4 of the power cable 3 and a screw 18b for fastening the clamp 18a. The sheath of the power cable 3 can be clamped with the strain relief device 18, so that a tensile force acting on the power cable 3 is absorbed by the strain relief device 18 and cannot loosen the connecting cables 11 clamped by means of the clamping device 10.

Claims (10)

1. Apparatus (8) for connecting a power cable (3) to an electronic unit (9) of a power tool (1), having at least one clamping means (10) for clamping a connecting line (11) of the power cable (3) and a contacting means (12) for establishing an electrical contact between the connecting line (11) clamped by means of the clamping means (10) and the electronic unit (9),
   characterized in that the clamping means (10) and the contacting means (12) are arranged on a connecting element (14) extending through an opening (15) in a housing element (16), which spatially separates the clamping means (10) from the electronic unit (9), the opening (15) being sealed by means of a sealing means (20) resting against the connecting element (14).
2. Apparatus according to claim 1,
   characterized in that the sealing means (20) is formed in one piece with the housing element (16) and has a considerably smaller wall thickness than the housing element (16).
3. Apparatus according to claim 2,
   characterized in that the sealing means (20) is formed as a sealing lip extending around the opening (15) of the housing element (16).
4. Apparatus according to any one of claims 1, 2 or 3,
   characterized in that the housing element (16) is formed at least partly as the bottom of a power cable exchange chamber (7).
5. Apparatus according to claim 4,
   characterized in that the power cable exchange chamber (7) is closable by means of a removable cover (5).
6. Apparatus according to claim 5,
   characterized in that the cover (5) can be sealed with respect to the housing element (16) by means of a tongue-and-groove connection (17).
7. Apparatus according to any one of claims 1 to 6,
   characterized in that a strain relief device (18) with which a sheathing (4) of the power cable (3) can be clamped.
8. Apparatus according to any one of claims 1 to 7,
   characterized in that the contacting means (12) comprises a metallic contact element (12a).
9. Apparatus according to any one of claims 1 to 8,
   characterized in that two connecting elements (14) with respective clamping means (10) and respective contacting means (12) are provided.
10. Power tool (1) having a power cable (3), an electronic unit (9) and an apparatus (8) for connecting the power cable (3) to the electronic unit (9) according to any one of claims 1 to 9.

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