EP2201584B2 - Coupling device - Google Patents

Description

The invention relates to a coupling device for a system for contactless energy and data transmission.

From the DE 199 32 504 A1 is a realization of a contactless energy and data transmission of two mutually rotatable parts, in which two or more coils are rotatably mounted, at least one of the coils being in one half, which has an L-shaped cross section.

From the DE 4125143 a device for the contactless transmission of alternating signals is known. The device discloses (column 4, lines 18-42, FIGS. 10-12) transmitters and receivers which can be driven to rotate concentrically with one another. Both parts contain both flat conductor loops, which act as coils for inductive coupling, and coupling capacitors in the form of metal foils. Both coupling devices are housed together within a shielding housing.

From the CA 2 071 681 A1 a device for transmitting power and energy in a vehicle is known as the closest prior art.

From the DE 41 25 143 A1 a device for the contactless transmission of alternating signals is known.

From the US 5 814 900 A1 an arrangement for a combined transmission of energy and electrical signals is known.

From the US 4,674,814 a connection arrangement is known.

From the JP 2002 198 238 A data and power transmission for a rotating connection is known.

From the EP 1 241 058 A2 a rotary, non-contacting connector is known.

From the GB 2 381 075 A contactless data transmission in a rotating machine is known.

From the US 7 425 096 B2 a gantry for an X-ray device is known.

The invention is based on the object of developing a system with contactless energy and data transmission, the error rate of the transmission being reduced.

According to the invention the object is achieved in the coupling device according to the features specified in claim 1.

• eine Primärwicklung und eine Sekundärwicklung ein induktives Koppelelement bilden, wobei
  die Primärwicklung am ersten Gehäuseteil konzentrisch zur Achse angeordnet ist und die Sekundärwicklung am zweiten Gehäuseteil konzentrisch zur Achse angeordnet ist,
• am ersten Gehäuseteil eine elektrisch leitfähige Koppelfläche ausgebildet ist und am zweiten Gehäuseteil eine elektrisch leitfähige Koppelfläche ausgebildet ist, die zusammen ein kapazitives Koppelelement bilden,

dass das induktive Koppelelement von einer magnetischen Abschirmung umgeben ist und dass die kapazitiven Koppelelemente außerhalb der magnetischen Abschirmung des induktiven Koppelelements angeordnet sind.Important features of the invention in the coupling device are that a first housing part and a second housing part are provided, which are mounted rotatably relative to one another about an axis, wherein

• a primary winding and a secondary winding form an inductive coupling element, wherein
  the primary winding is arranged concentrically to the axis on the first housing part and the secondary winding is arranged concentrically to the axis on the second housing part,
• an electrically conductive coupling surface is formed on the first housing part and an electrically conductive coupling surface is formed on the second housing part, which together form a capacitive coupling element,

that the inductive coupling element is surrounded by a magnetic shield and that the capacitive coupling elements are arranged outside the magnetic shield of the inductive coupling element.

The induction of eddy currents is thus further reduced by the inductive transmission into the capacitive coupling elements and interference sources for data transmission are kept away from the transmission area.

In an advantageous embodiment, a first pair of coupling surfaces is formed on the first housing part and a second pair of coupling surfaces is formed on the second housing part, a contact surface of the first pair each forming a capacitive coupling element with a contact surface of the second pair.
The advantage here is that the power transmission signal cannot crosstalk to the data transmission signal. The transmission errors are thus reduced. Another advantage is that large currents can be transmitted with the inductive coupling element and thus a power supply is possible, while with the capacitive coupling elements, data signals with a low current are transmitted with little distortion.

The magnetic shield is preferably arranged between the inductive coupling element and the capacitive coupling elements.

According to the invention, the coupling surfaces are formed by metallic, ring-shaped bands, the surface of which is arranged radially to the axis of rotation. The capacitive coupling elements are thus functional independently of the rotational position because the electrical coupling surfaces emulate the rotational symmetry of the coupling device.

In an advantageous embodiment, the coupling surfaces of each pair are arranged on a common, imaginary cylinder. A compact size is thus provided.

In an advantageous embodiment, the turns of the primary winding and the secondary winding each run around the axis of rotation. The advantage here is that the power supply is available regardless of the rotational position of the coupling device.

In an advantageous embodiment, the primary winding and the secondary winding are each connected to a plug which has a pull-out protection. So is one high current, for example of more than 10 A, can be transmitted, and the system has increased safety.

In an advantageous embodiment, the inductive coupling element is arranged radially within the capacitive coupling elements. The advantage here is that the inductive coupling element can be implemented with a small footprint and that the capacitive coupling can be implemented inexpensively.

In an advantageous embodiment, each contact surface has a ring width of 1 cm to 3 cm, in particular 2 cm. The coupling surfaces of each capacitive coupling device are preferably spaced apart by 0.5 cm to 2 cm, in particular 1 cm. Particularly favorable conditions for data transmission are thus achieved.

According to the invention, the coupling surfaces of the capacitive coupling devices each form an electrically conductive ring which is electrically severed at one point. Circulating eddy currents, which would be induced in the capacitor surfaces of the capacitive coupling elements by the inductive coupling element, are thus interrupted.

According to the invention, the coupling surfaces of the capacitive coupling devices are each connected to connecting means in the middle between the ends formed by the severing. Good data coupling is thus achieved.

According to the invention, the coupling surfaces of the capacitive coupling devices have gaps or incisions running transversely in the circumferential direction. Eddy currents which would be induced in the capacitor areas of the capacitive coupling elements by the inductive coupling element are thus further reduced.

In an advantageous embodiment, the coupling surfaces are each fastened on an electrically insulating base. This enables undisturbed data transmission via the communication channel formed by the coupling surfaces.

Further advantages result from the subclaims. The claims define the subject of the request for protection by specifying the technical features of the invention.

• Figur 1 einen erfindungsgemäßen Drehübertrager,
• Figur 2 eine Schnittansicht durch den Drehübertrager nach Figur 1,
• Figur 3 eine Schnittansicht durch einen weiteren Drehübertrager,
• Figur 4a eine Kupferband für ein Koppelelement eines Drehübertragers,
• Figur 4b ein weiteres Kupferband für ein Koppelelement eines Drehübertragers und
• Figur 5 das elektronische Prinzipschaltbild eines Drehübertragers.

The invention will now be explained in more detail with the aid of figures:
It shows

• Figure 1 a rotary transformer according to the invention,
• Figure 2 a sectional view through the rotary transformer after Figure 1 ,
• Figure 3 2 shows a sectional view through a further rotary transformer,
• Figure 4a a copper strip for a coupling element of a rotary transformer,
• Figure 4b another copper strip for a coupling element of a rotary transformer and
• Figure 5 the electronic block diagram of a rotary transformer.

Figure 1 shows a rotary transformer 1 according to the invention. A first housing part 2 is connected to a second housing part 3 by a connecting ring 4. The first housing part 2 and the second housing part 3 can be rotated relative to one another about the axis of the connecting ring 4.

A connection box 5 is formed on each of the first housing part 2 and the second housing part 3. A connector 6 for heavy current, that is to say for more than 10 A, and a BNC connector 8 for connecting a high-frequency line are formed on each connection box 5.

A foldable bracket on the plug 6 forms a pull-out protection 7 for the plug of the power line.

The first housing part 2 and the second housing part 3 are made of plastic.

Figure 2 shows an axial section through the rotary transformer Figure 1 .

The connecting ring 4 is connected to a hollow shaft 10 by screws 9. This forms a bearing in which the first housing part 2 and the second housing part 3 are rotatably arranged.

The plug 6 is connected by lines, not shown, to connections 22, which in turn are connected to the two ends of a primary winding 20. The windings of the primary winding 20 run around the axis of rotation of the rotary transformer. Thus creates a Alternating current, which is impressed into the primary winding 20 via the plug 6, a magnetic field which passes through a secondary winding 21 running in a ring around the axis of rotation and induces a current in the secondary winding 21. The secondary winding 21 is fixedly connected to the second housing part and connected to an in via connections and conductors, not shown Figure 2 not visible connector 6 connected. Primary winding 20 and secondary winding 21 have a common axis. The primary winding and secondary winding thus form an inductive coupling element, and energy can be transmitted inductively via the swivel joint. An air gap 24 is set up between the primary winding 20 and the secondary winding 21, which enables the first and second housing parts to be rotated relative to one another.

Primary winding 20 and secondary winding 21 are each encompassed by cross-sectionally U-shaped, annular trough-shaped shields 23, the openings of which face one another. Thus, the magnetic field generated by the primary winding and the secondary winding is enclosed and essentially does not come out of the ring area enclosed by the shields 23.

Outside the shields 23, a ring insert 25, which is concentric with the axis of rotation, is formed on the first housing part 2, on the inside of which a pair of annular copper strips 26, 27 are attached. The copper strips 26, 27 are electrically connected to the two connections of the BNC connection 8 in the connection box 5 of the first housing part 2.

Between the ring insert 25 and the shields 23, a second concentrically extending ring insert 31 is formed on the second housing part 3, on the outside of which a further pair of ring-shaped copper strips 28, 29 is arranged. The copper strips 28, 29 are electrically connected to the two connections of the BNC connection 8 in the connection box 5 of the second housing part 3.

The ring inserts 25, 31 are arranged concentrically one inside the other and thus allow an unrestricted rotary movement of the rotary connector.

The copper strips 26, 27, 28, 29 are aligned radially, that is to say the normal to the surface points in each case in the radial direction with respect to the axis of rotation. The copper bands 26 and 28 are arranged opposite one another in the same axial position and thus form a capacitive coupling element in the form of a capacitor. Likewise, the copper strips 27 and 29 are arranged opposite one another in the same axial position and thus form a second capacitive coupling element in the form of a capacitor.

The two capacitive coupling elements operated in parallel enable RF signals to be transmitted from the BNC connector 8 of the first housing part 2 to the BNC connector 8 of the second housing part 3 in a contactless manner, regardless of the rotational position of the rotary transmitter.

The ring width of the copper strips 26, 27, 28, 29 used is 2 cm, the copper strips 26, 27, 28, 29 of each capacitive coupling element are 1 cm apart.

Figure 3 showed another embodiment of a rotary transmitter according to the invention. A sectional view of one side of the rotary transmitter is shown. The axis of rotation 31 is indicated by a chain line. The representation of the bearings and the electrical connections has been suppressed to improve the clarity of the drawing.

An annular trough 33 made of ferromagnetic material is let into a first housing part 2. The primary winding 32 is wound into this trough 33. An annular carrier 35 engages with the secondary winding 34 in the space enclosed by the trough 33. The primary winding 32 is thus arranged radially within the secondary winding 35.

The ring-shaped carrier 35 is fastened to the second housing part 3. A cover 36 made of ferromagnetic material is worked into the second housing part 3 and closes the trough 33 in a ring shape. Thus, the interior of the trough 33, which receives the primary winding 32 and the secondary winding 34, is magnetically sealed off from the outside area.

The first housing part 2 and the second housing part 3 are rotatably supported relative to one another about the axis of rotation 31. A gap 37 is formed between the housing parts, which has an axially running, rotationally symmetrical region 38 and ends in a labyrinth seal 30.

A first pair of copper strips 26, 27 is embedded in the side walls of area 38 and, opposite the pair of copper strips 26, 27, a second pair of copper strips 28, 29. The copper strips 26, 27, 28, 29 are fastened on an electrically non-conductive base and electrically isolated from each other and from the environment.

A first copper strip 26 of the first pair thus forms, together with a first copper strip 28 of the second pair, a capacitor and thus a first capacitive coupling element. Likewise, the second copper strip 27 of the first pair, together with the second copper strip 29 of the second pair, forms a capacitor and thus a second capacitive coupling element. Thus, signals can be transmitted via the capacitive coupling elements in any rotational position of the rotary transmitter and independently of a rotary movement.

Air is arranged between the two copper strips belonging to each capacitive coupling element.

The first capacitive coupling element and the second capacitive coupling element jointly form a transmission channel for data transmission.

In further developments, the copper strips 26, 27, 28, 29 of the rotary transformer are designed in such a way that the lowest possible eddy currents are induced by the inductive coupling element.

Figure 4a shows a first example of such a development, which is not included in the invention. In order to form a copper strip 40, transverse strips 42 made of copper are arranged on a longitudinal strip 41 made of copper and electrically connected thereto, so that gaps 43 are formed between the transverse strips 42. These gaps reduce induced eddy currents in the copper strip 40.

The copper strip 40 is assembled at the ends 44 to form an annular copper band. In an alternative example, ends 44 become one but one Gap assembled so that no circular currents can flow along the longitudinal strip 41.

Figure 4b shows an exemplary embodiment according to the invention for a further development of the copper strips 26, 27, 28, 29.

In a copper strip 30, cuts 45 are alternately made laterally in the longitudinal direction, so that overall a meandering conductor results. The copper strip 40 is assembled at the ends 44 to form an annular copper band. In this exemplary embodiment, the ends 44 are put together except for a gap, so that no circular currents can flow along the copper strip 40.

Figure 5 shows the basic circuit diagram of a contactless energy and data transmission via a freely rotatable coupling.

A rotary transmitter 61 designed as a transmitter head comprises a primary side 56 and a secondary side 57 of a transformer, which are arranged such that they can be rotated relative to one another. The transformer forms the inductive coupling element for contactless power transmission.

The primary side 56 is fed from a generator 54 with a constant alternating current with a current of 10 A or 60 A and a frequency of 25 kHz. Other frequencies between 10 kHz and 200 kHz can also be provided.

This alternating current is passed on to a rectifier 55 via the transformer. To increase the coupling strength, the rectifier comprises a resonant circuit whose resonant frequency is matched to the frequency of the alternating current fed in.

The rectifier 55 supplies a consumer 60, for example a converter or a motor or an electronic circuit.

The generator 54 also supplies a modem 50 and a transceiver 52. The modem 50 receives data via a line (not shown) and passes this on to the transceiver 52 as signals. The transceiver 52 amplifies the signals.

The rotary transformer 61 comprises a first capacitor 58 and a second capacitor 59. The capacitors 58, 59 form the capacitive coupling elements of a transmission channel for data transmission.

The capacitors 58, 59 are each designed such that the two plates are movable relative to one another.

Signals can be transmitted from the transceiver 52 to the transceiver 53 and vice versa via the capacitors 58, 59 arranged in parallel. A return via a ground line is not necessary. This reduces the susceptibility to faults.

The transceiver 53 is fed from the alternating current transmitted via the inductive coupling element, in particular from the rectifier 55. The signals come from the transceiver 53 to the modem 51, which is also supplied by the rectifier 55.

Conversely, the modem 51 can send data to the transceiver 53 that is received in the modem 50.

A bidirectional data exchange is thus provided via a movable coupling device, an inductive coupling for energy being provided in parallel with the coupling for the data exchange, from which a consumer and the transceivers 52, 53 and / or the modems 50, 51 are supplied.

Reference list

• 1 rotary transformer
• 2 housing part
• 3 housing part
• 4 connecting ring
• 5 junction box
• 6 plugs
• 7 Pull-out protection
• 8 BNC connector
• 9 screw
• 10 wave
• 20 primary winding
• 21 secondary winding
• 22 connection
• 23 shielding
• 24 air gap
• 25 ring insert
• 26, 27, 28, 29 copper tape
• 30 labyrinth seal
• 31 axis of rotation
• 32 primary winding
• 33 trough
• 34 secondary winding
• 35 carriers
• 36 lid
• 37 gap
• 38 area
• 40 copper strips
• 41 vertical stripes
• 42 horizontal stripes
• 43 gap
• 44 strip end
• 45 incision
• 50, 51 modem
• 52, 53 transceiver
• 54 generator
• 55 AC / DC converters
• 56 primary side
• 57 secondary side
• 58, 59 capacitor
• 60 consumers
• 61 rotary transformers

Claims (11)

1. A coupling device
   having a first housing part and a second housing part which are mounted rotatable relative to one another about an axis, wherein

   - a primary winding and a secondary winding form an inductive coupling element, wherein
   the primary winding is arranged on the first housing part in a manner concentric to the axis and the secondary winding is arranged on the second housing part in a manner concentric to the axis,

   - in that at the first housing part there is an electrically conductive surface as a first coupling surface,
   and at the second housing parts there is formed an electrically conductive surface as a second coupling surface,
   which coupling surfaces together form a capacitive coupling element,

   wherein the inductive coupling element is surrounded by a magnetic shield,
   wherein the capacitive coupling elements are arranged exterior to the magnetic shield of the inductive coupling element,
   characterized in that
   the coupling surfaces of the capacitive coupling elements are each in the form of an electrically conductive ring which is electrically severed at one site,
   wherein in the centre and between the ends formed by the severing, the coupling surfaces of the capacitive coupling elements are each connected to connection means,
   wherein the coupling surfaces are formed by metallic, annular bands whose surface is in each case arranged radially to the rotational axis,
   wherein in a circumferential direction, the coupling surfaces of the capacitive coupling elements have incisions running transversely in an alternating manner in such a way that the respective coupling surface is in the form of a meander-shaped copper strip.
2. A coupling device according to claim 1,
   characterised in that

   - electrically conductive surfaces form a first pair of coupling surfaces at the first housing part and electrically conductive surfaces form a second pair of coupling surfaces at the second housing part
   wherein each electrically conductive surface, in particular coupling surface, of the first pair forms a capacitive coupling element with a respective electrically conductive surface, in particular coupling surface, of the second pair.
3. A coupling device according to any one of the preceding claims,
   characterised in that
   the housing parts are manufactured from plastics material or
   an electrically insulating material is provided between the housing parts and the respective electrically conductive surfaces.
4. A coupling device according to any one of the preceding claims,
   characterised in that
   the magnetic shield is arranged between inductive coupling element and capacitive coupling elements.
5. A coupling device according to any one of the preceding claims,
   characterised in that
   the coupling surfaces of each pair are arranged on a common, notional cylinder.
6. A coupling device according to any one of the preceding claims,
   characterised in that
   the windings of the primary winding and the secondary winding each run around the rotational axis.
7. A coupling device according to at least one of the preceding claims,
   characterised in that
   the primary winding and the secondary winding are each connected to a connector which has an anti pull out device.
8. A coupling device according to at least one of the preceding claims,
   characterised in that the inductive coupling element is arranged radially within the capacitive coupling elements.
9. A coupling device according to at least one of the preceding claims,
   characterised in that
   each contact surface has a ring width from 1 cm to 3 cm, in particular 2 cm.
10. A coupling device according to at least one of the preceding claims,
    characterised in that
    the coupling surfaces of each capacitive coupling element are 0.5 cm to 2 cm apart, in particular 1 cm.
11. A coupling device according to the preceding claim,
    characterized in that
    the coupling surfaces are each secured on an electrically insulating base.

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