AU709226B2

AU709226B2 - Improved rotating electrical connector

Info

Publication number: AU709226B2
Application number: AU49475/96A
Authority: AU
Inventors: Gerard Biscaras; Michel Haller; Fabrice Rodier
Original assignee: Magneti Marelli France SAS
Current assignee: Marelli France SAS
Priority date: 1995-03-03
Filing date: 1996-03-01
Publication date: 1999-08-26
Anticipated expiration: 2016-03-01
Also published as: AU4947596A; DE69605774D1; WO1996027924A1; FR2731299B1; EP0813756A1; BR9607468A; AR001145A1; DE69605774T2; FR2731299A1; PL322466A1; ES2140827T3; EP0813756B1; PL181222B1

Description

IMPROVED ROTATING ELECTRICAL CONNECTOR The present invention relates to the field of rotating electrical connectors.

More precisely, the present invention relates to connectors comprising: a first fixed case member, a second movable case that rotates relative to the first fixed member and a flexible electrical connection member disposed between the fixed member and the movable member of the case and connected to said member.

The present invention may be applied particularly but not exclusively to the transmission of electrical signals between means connected to the steering-wheel of an automobile, for example an inflation system for an airbag-type protection device and control means independent of the steering-wheel but connected to the steering column.

Many rotating electrical connectors of the type described above have already been proposed.

General descriptions of such connectors can be found in documents GB-A-869275, GB-A-2216476, US-A- 3525536, FR-A-2494922, FR-A-2667457, US-A-4789342, US- A-4540223, FR-A-2667458, FR-A-2667456, FR-A-2477789, DE-A-751684, FR-A-2249458, GB-A-2164506, CH-A-167629, US-A-4422699, US-A-4836795, DE-A-3041258, US-A-4451105, US-A-3525536, US-A-4722690, US-A-4875860.

FR-A-2665805 and US-A-5046951 describe rotating electrical connectors of this type comprising a first fixed case member, a second rotating case member and a flexible conducting member that also comprise an intermediary member disposed between the first fixed 2 a..

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*S S S a 9 case member and the second rotating movable case member, wherein the intermediary member is impelled to rotate synchronously with the second rotating movable case member with a predetermined speed-reduction ration by means of at least one engine gear that coordinates with the two fixed and movable case organs, and the flexible conducting member is disposed in a loop on said intermediary member.

Documents US-A-4540223, US-A-5219460 and US-A- 3763455 describe other rotating electrical connectors in which an intermediary member disposed between the two fixed and rotating movable case members, and on which the flexible conducting member is disposed in a loop, moves freely in relation to the two fixed and rotating movable case members and said flexible conducting member displaces said intermediary member.

The purpose of the present invention is to improve on known rotating electrical connectors.

This aim is achieved in the present invention by providing a rotation electrical connector of known type comprising two case members capable of rotation relative to one another, a flexible conducting member disposed between 25 these two members, and an intermediary member disposed between the two case members to define two chambers, one internal, the other external, between this intermediary member and respectively one of the case members, said intermediary member being capable of moving freely of said case members and having an opening generally radial in which is placed the flexible conducting member so that the flexible conducting member is curved inwards in a loop on the intermediary member, characterised in that the radial opening formed in the intermediary member produces on the flexible conducting member a stress so that the flexible conducting member moves itself in the radial opening and impels the intermediary member only when the part of the I~b~PI\L ^i \\melbl\home\Monique\Keep\pei\49475-96.doc 29/06/99 2a flexible conducting member contained in one of the chambers, defining an auxiliary chamber, is fully pressed against the surface of the intermediary member defining this auxiliary chamber so that this auxiliary chamber receives a variable number of turns of the flexible conducting member that are the equivalent of a substantially constant length of said member depending on whether said turns are pressed against said intermediary member or said associated case member defining the auxiliary chamber during a relative rotational displacement of the two case members, but without any detectable relative rotation between said intermediary member and the other case member.

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*i *i In another advantageous characteristic of the present invention the auxiliary chamber is a chamber within the intermediary member defined between the intermediary member and a central member constituting one of the two case members.

In another advantageous characteristic of the present invention the auxiliary chamber is defined between the intermediary member and the rotating movable case member.

Other characteristics, aims and advantages of the present invention will be better understood from the following detailed description. The description is a non-limitative example and refers to the attached Figures where: Figure 1 is a schematic diagram of a cross-section of a rotating electrical connector according to the present invention, Figures 2 and 3 are similar views of cross-sections of the same connector in relatively different positions of the two basic members constituting the case, Figures 4 and 5 are two perspective views of a rotating electrical connector according to the present invention.

The attached Figures show a rotating electrical connector mainly consisting of a first fixed case member 100, a second rotating case member 200, an electricity-conducting member 300 and an intermediary member 400.

In the non-limitative embodiment shown in the attached Figures the first, fixed member of case 100 defines an external cylindrical cage while the second rotating movable member 200 defines a central cylindrical cage. This disposition may, however, be reversed in that the fixed case member may be central N while the movable member defines an external cage.

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Fixed and movable case members 100, 200 may be the subject of many different embodiments, particularly as concerns the structure defining the housing in which conducting member 300 is placed, the respective fastening methods and electrical connections with the ends of conducting member 300, or the way reception across the ends of said conductor 300 occurs. For this reason no detailed description of the components comprising case members 100, 200 is given below.

Flexible electrical connecting member 300 may also be the subject of many different embodiments. Using known techniques this may, for example, be a bundle of mutually-insulated electricity- conducting cables, or preferably a printed circuit or flexible plastic film fitted with several parallel metallized tracks.

The ends of flexible conductor 300 are connected respectively to electrical contacts disposed within connector bodies provided on case members 100, 200, or the ends of flexible conductor 300 may be threaded through and supported by said case members 100, 200 to be connected to external peripheral members such as, for example, an inflation system for an airbag-type protection device and control means for said system.

On the attached Figures the axis of rotation of case members 100, 200 is marked 0-O.

Intermediary member 400 is disposed between the case members 100, 200. Intermediary member 400 moves freely in relation to case members 100, 200, i.e.

contrary to some previously-proposed connectors such as those described in, for example, documents FR-A-2665805 and US-A-5046951, intermediary member 400 is not connected to case members 100, 200 by means of at least one engine gear that defines a predetermined, imposed displacement ratio between intermediary member 400 and said case members 100, 200.

In other words, intermediary member 400 is simply guided in its rotation around said axis O-0 between case members 100 and 200.

As can be seen from the attached drawings, intermediary member 400 together with central case member 200 defines an auxiliary chamber 402. According to the invention this chamber 402 is adapted to receive a variable number of turns of conducting member 300 that are the equivalent of a more or less constant length of said member depending on whether said turns are pressed against said intermediary member, as shown in Figure 2, or against said case member 200 defining the auxiliary chamber, as shown in Figure 1, during a relative rotation displacement of the two case members 100, 200 but without any detectable relative rotation between said intermediary member 400 and the other case member 100.

Furthermore, as can be seen from the attached Figures, according to the invention flexible conducting member 300 is curved inwards in a loop on the intermediary member 400. For this reason the winding direction of conducting member 300 in auxiliary chamber 402 (clockwise moving towards center of rotation

O-O)

is contrary to the winding direction of the same conducting member 300 external to intermediary member 400 (clockwise moving away from center of rotation

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O).

More precisely, according to the preferred embodiment of the invention shown in the attached Figures, auxiliary chamber 402 has a cross-section that is generally crescent-shaped.

To this end, intermediary member 400 is principally defined by two cylindrical walls, 410, 420 that have different radii.

External cylindrical wall 410 is centered on axis of rotation O-0. In contrast, internal cylindrical wall 420 is off-center of axis of rotation O-0. The two walls 410, 420 connect tangentially. Auxiliary chamber 402 is defined between internal cylindrical wall 420 and the cylindrical rotor of case member 200.

Intermediary member 400 has a transverse opening 432 located in zone 430 diametrically opposite the connection zone 422 between walls 410, 420. This opening is generally radial in relation to axis of rotation

O-O.

More precisely, this opening 432 is preferably curved inwards, having, for example, the shape of a semicylindrical sector, to connect tangentially with the internal surface of wall 420 and the external surface of wall 410 respectively.

The inwardly-curved shape of opening 432 in which conducting member 300 is engaged, and in which the flexible conducting member is inwardly curved in a loop as described above, is designed to avoid damaging conducting member 300.

The connector described above operates essentially as follows.

During a clockwise rotation of the central member of case 200 (connected, for example, to the steering wheel of the vehicle) starting from the position of the connector shown in Figure 1, conducting strip 300 leaves the external chamber formed between the external surface of intermediary member 400 and the internal surface of case member 100 to wind itself around the external diameter of case member 200.

During this movement conducting strip 300 is subject to stress as it passes through opening 432.

Intermediary member 400 is consequently impelled by conducting strip 300 to rotate concentrically with axis O-0.

During a rotation in the opposite direction, i.e.

an anticlockwise rotation of case member 200, the

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radius of curvature of opening 432 produces stress on conducting strip 300 that makes a certain torque necessary to impel intermediary member 400.

The free section of strip 300 wound around the external diameter of case member 200 can then unwind towards the internal surface of intermediary member 400, as shown in Figure 2.

When, starting from the position shown in Figure 2, central case member 200 is again rotated clockwise, conducting strip 300 is again wound into turns with a smaller radius on the external surface of case member 200 as shown in Figure 1.

By contrast, when, starting from the position shown in Figure 2 in which the turns of the strip housed in auxiliary chamber 402 are fully pressed against the internal surface of intermediary member 400, rotation of case member 200 is continued anticlockwise, conducting strip 300 is pressed against concave surface 433 of opening 432. Conducting strip 300 then impels intermediary member 400 anti-clockwise as shown in Figure 3 and conducting strip 300 leaves auxiliary chamber 402 to take up a position between the external surface of intermediary member 400 and the internal surface of case member 100. During this movement conducting strip 300 is again subjected to stress in opening 432, more precisely at concave surface 433 of said opening.

In the present invention auxiliary chamber 402 is preferably dimensioned to receive conducting strip 300 whose length is the equivalent of approximately 80% of the relative displacements required for use between case members 100, 200 without causing displacement of intermediary member 400.

A specialist in the trade will understand that the rotating electric connector described above uses shorter connecting strips than those required by the systems of the prior art.

The rotating electrical connector can, in fact, use a short connecting strip 300 in two different configurations depending on the angular travel used by the apparatus.

The first configuration is based on a short range of movement of the strip, typically a relative rotation between case members 100, 200 of less than one turn. In this first configuration the strip unwinds from the external diameter of central case member 200 towards the internal surface of intermediary member 400 and vice versa as shown in Figures 1 and 2. The limited use of this principle of tightening and releasing turns of a strip inside a chamber on the angular travel required makes it possible to use a reduced length of conducting strip 300 compared with earlier apparatuses that required the same type of tightening and releasing turns of a strip 300 for the entire range of relative rotation possible between case members 100 and 200.

The second operating configuration of the connector according to the invention uses the full range of movement, i.e. a relative rotation between case members 100, 200 through the maximum possible range. The present configuration uses the reversal of strip 300 in opening 432 of the intermediary member. As has already been shown above, this reversal makes it possible to limit the length of strip 300 as compared with connectors in which strip 300 is a single turn that does not reverse.

In contrast, the present invention has numerous advantages over the rotating electrical connectors using the known art.

In particular, it makes it possible to use a shortened strip 300 while limiting the stresses applied PN to strip 300. In fact, during 80% of its operation

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strip 300 is not displaced in relation to opening 432 in intermediary member 400 and consequently undergoes no particular stress.

The present invention is clearly not limited to the embodiment described above but may be extended to cover any variant using the same principles.

In particular, the invention may easily be adapted to a variant in which auxiliary chamber 402 is formed not inside intermediary member 400 but outside said member, i.e. between the external surface of intermediary member 400 and the internal surface of case member 100.

Flexible conductor member 300 is preferably positioned at its mid-point and the length of that part of the member placed in auxiliary chamber 402 is of the order of half the total length of said member 300.

The rotating electrical connector described above has an off-center auxiliary chamber 402. When flexible conductor 300 is pressed against the internal surface of cylindrical wall 420 of intermediary member 400 it applies a tilting torque to the member thereby causing bracing of said intermediary member. Furthermore, during use a first resisting torque due to the friction between the turns of flexible conductor 300 is produced together with a resisting torque due to friction between intermediary member 400 and case members 100, 200.

The connector may be further improved as shown in Figures 4 and 5 by guiding intermediary member 400 on moving member 200. The guide used may consist of a gill 440 formed in the periphery of intermediary member 400, said gill 440 being housed in complementary throat 240 of movable member 200.

Movable member 200 therefore tends to impel intermediary member 400, thereby eliminating the torque produced by the bracing.

Stops may also be provided on the rotating electrical connector between fixed member 100 and movable member 200, or between intermediary member 400 and either member 100 or 200 to limit the permitted angle of rotation between members 100 and 200 to, as a non-limitative example, five turns.

In this context, two permitted extreme configurations of flexible conducting member 300 may be realized: in one, the flexible conducting member is fully wound in the form of turns tightened against central member 200 of auxiliary chamber 402; in the other configuration flexible conducting member 300 lies entirely inside the chamber between intermediary member 400 and external member 100.

The second configuration may, however, be modified so that the mechanical stops permit an extreme position in which a certain length of conducting strip 300 remains inside auxiliary chamber 402. This arrangement increases the range of angular movement permitted between members 100 and 200 without displacement of intermediary member 400 by simply varying the mean diameter of the turns in auxiliary chamber 402. In other words, this arrangement increases the angular operating range of the connector without displacing the flexible conducting member 300 in passage 432.

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Claims

1. Rotation electrical connector of known type comprising two case members capable of rotation relative to one another, a flexible conducting member disposed between these two members, and an intermediary member disposed between the two case members to define two chambers, one internal, the other external, between this intermediary member and respectively one of the case members, said intermediary member being capable of moving freely of said case members and having an opening generally radial in which is placed the flexible conducting member so that the flexible conducting member is curved inwards in a loop on the intermediary member, characterised in that the radial opening formed in the intermediary member produces on the flexible conducting member a stress so that the flexible conducting member moves itself in the radial opening and impels the intermediary member only when the part of the flexible conducting member contained in one of the chambers, defining an auxiliary chamber, is fully pressed against the surface of the intermediary member defining this auxiliary chamber so that this auxiliary chamber receives a variable number of turns of the flexible conducting member that are the equivalent of a substantially constant length of said member depending on 0 whether said turns are pressed against said intermediary member or said associated case member defining the auxiliary chamber during a relative rotational displacement of the two case members, but without any detectable relative rotation between said intermediary member and the other case member.

2. Connector of Claim 1 characterised in that auxiliary chamber is a chamber within the intermediary >35 member defined between the intermediary member and a central member constituting one of the two case members. 'r \\melbO1\homeS\Moniqu~e\Keep\speci\49475-96.doc 29/06/99 12

3. Connector of Claim 1 characterised in that auxiliary chamber is a chamber external to the intermediary member defined between the intermediary member and an external member constituting one of the two case members.

4. Connector of any one of the preceding Claims characterised in that the auxiliary chamber is defined between intermediary member and mobile rotating case member.

Connector of any one of the preceding Claims characterised in that the intermediary member is defined by two off-center cylindrical walls. 15

6. Connector of claim 5 characterised in that one of the external cylindrical walls is centred on the axis of rotation of the connector while the other, internal cylindrical wall is off-center in relation to axis of rotation.

7. Connector of Claim 5 or 6 characterised in that the two cylindrical walls are tangentially connected.

8. Connector of any one of the preceding claims characterised in that the opening curves inwards and has the shape, for example, of a sector of a cylinder.

9. Connector of any one of the preceding claims characterised in that the auxiliary chamber has the general shape of a crescent.

Connector of any one of the preceding claims characterised in that the auxiliary chamber is dimensioned to receive a length of conducting strip that permits relative rotary displacements between the two case members of approximately 80% of the operation of the connector without causing relative displacement of intermediary F member. \\melbOl\home$\Monique\Keep\speci\49475-96.doc 29/06/99 13

11. Connector of any one of the preceding claims characterised in that the intermediary member is guided by the movable member.

12. Connector of claim 11 characterised in that guided of the intermediary member on movable member is achieved by housing a gill in a complementary throat on said members.

13. Connector of any one of the preceding claims characterised in that stops are provided between fixed member and movable member, or between intermediary member and either member to limit the permitted angle of rotation between members to, as a non-limitative example, five 15 turns. a

14. Connector of any one of the preceding claims a characterised in that two permitted extreme configurations for flexible conducting member may be realised: in one, the flexible conducting member is fully wound in the form of turns tightened against case member that defines auxiliary chamber; in the other configuration flexible conducting member is entirely disposed between intermediary member and the other member of the case.

15. Connector of any one of the preceding claims characterised in that two permitted extreme configurations for flexible conducting member may be realised: in one, the flexible conducting member is fully wound in the form of turns tightened against case member defining auxiliary chamber; in the other configuration flexible conducting member is partly disposed between intermediary member and the other member of the case and partly disposed in the auxiliary chamber. 04 \\melb01\home$\Monique\Keep\speci\49475-96.doc 29/06/99 A// 14

16. Rotating electrical connector substantially as herein described with reference to and as illustrated by the accompanying drawings. Dated this 29th day of June 1999 MAGNETI MIARELLI FRANCE By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia *\\Me b01\home$\Monique\Keep\speci\49475-96.doc 29/06/99