FR2753842A1 - IMPROVED ROTATING ELECTRIC CONTACTOR - Google Patents

Abstract

The invention concerns a rotary electric contactor comprising two housing elements (100, 200) capable of relative rotation, a flexible conductive member (300) set between these two elements (100, 200), and intermediate element (400) set between the two housing elements (100, 200) to define an auxiliary chamber (402) between itself and one of the housing elements, said housing element (200) defining the auxiliary chamber (402) in combination with the intermediate element (400). The auxiliary chamber is provided with a strip (500) capable of pivoting between a first retracted position on said housing element (200) when the contactor is driven in a direction which tends to press this conductive member (300) against this element (200), and a second position in which said strip (500) extends across the auxiliary chamber (402), between said housing element (200) and the intermediate element (400) when the contactor is driven in the opposite direction.

Description

 The present invention relates to the field of rotary electrical contactors.

 More specifically, the present invention relates to contactors of the type comprising: - a first fixed housing element, - a second housing element movable in rotation relative to the first fixed housing element, and - a flexible electrically conductive member placed between the fixed element and the movable element of the housing and connected to them.

 The present invention finds particular, but not exclusively, application to the transmission of electrical signals between means linked to the steering wheel of a motor vehicle, for example an inflation system of airbag type protective bag and means of independent control of the steering wheel linked to the steering column.

 Many rotary electrical contactors of the type recalled above have already been proposed.

One can find for example a general description of these contactors in the documents GB-A-869275, CB-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-75 1684, FR-A-224945 8, GB-A-2 164506,
CH-A-167629, US-A-4422699, US-A-4836795, DE-A-3041258, US-A-4451105, US-A-3525536, US-A-4722690, US-A-4875860.

 There have been described in documents FR-A-2665805 and US-A-5046951 rotary electrical contactors of the aforementioned type comprising a first fixed housing element, a second mobile rotationally rotating element and a flexible conductive member, which further comprise an intermediate member, placed between the first fixed housing member and the second movable rotating housing member, wherein the intermediate member is rotated in synchronism with the second movable rotating housing member with a predetermined reduction ratio of speed, by means of at least one motor pinion engaged between the two elements of the fixed and movable housing, and the flexible conductive member is arranged in a loop on this intermediate element.

US-A-4540223, US-A-5219460 and
US-A-3763455 of other rotary electrical contactors in which an intermediate element, placed between the two fixed and mobile casing elements in rotation, and on which the flexible conductive member is arranged in a loop, is provided freely movable relative to two fixed and mobile housing elements in rotation and the flexible conductive member displaces said intermediate element.

 The present invention now aims to improve the known rotary electrical contactors.

 This object is achieved according to the present invention by means of a contactor of the known type comprising two housing elements capable of relative rotation, a flexible conducting member placed between these two elements, an intermediate element, placed between the two housing elements, freely movable by relative to them, and the flexible conductive member is curved in a loop on the intermediate element, characterized in that the intermediate element defines an auxiliary chamber, between itself and one of the housing elements, adapted to receive a variable number of turns of the flexible conductive member corresponding to a substantially constant length of this member, depending on whether these turns are pressed against said intermediate element or said associated housing element defining the auxiliary chamber, during relative movement rotation of the two housing elements without significant relative rotation between said interm element diaire and the other housing element, and in that said housing element defining the auxiliary chamber in combination with the intermediate element, is equipped with a tongue capable of pivoting between a first retracted position on said housing element the contactor is driven in a direction which tends to press said conductive member against this element, and a second position in which said tongue extends across the auxiliary chamber, between said housing element and the intermediate element when the contactor is driven in an opposite direction.

 According to another advantageous characteristic of the present invention, the auxiliary chamber is a chamber internal to the intermediate element defined between the intermediate element and a central element making up one of the two housing elements.

 According to another advantageous characteristic of the present invention, the auxiliary chamber is defined between the intermediate element and the element of the mobile mobile housing.

 Other characteristics, objects and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings given by way of nonlimiting example and in which - FIG. 1 represents a schematic view in cross section of a rotary electrical contactor according to the present invention in a first direction of relative rotation, - Figure 2 shows another similar cross-sectional view of the same contactor, in a second direction of relative rotation of the two basic components the housing, - Figure 3 shows a perspective view of a rotary electrical contactor according to the present invention.

 There is shown in the appended figures, a rotary electrical contactor mainly comprising a first fixed box element 100, a second mobile rotating box element 200, an electrically conductive member 300 and an intermediate element 400.

 According to the particular and nonlimiting representation given in the appended figures, the first fixed housing element 100 defines an external cylindrical cage, while the second mobile rotating housing element 200 defines a central cylindrical cage. However, this arrangement can be reversed in the sense that the fixed housing element could be central while the mobile element would define an external cage.

 For the rest, the fixed and mobile housing elements 100, 200 can be the subject of numerous embodiments, in particular as regards the structure defining the housing for receiving the conductive member 300, their respective method of fixing and their mode of electrical connection with the ends of the conductive member 300, or of receiving them by crossing the ends of this conductor 300. For this reason, the particular structure of the housing elements 100, 200 will not be described in detail by the following.

 The flexible electrical conductor member 300 can also be the subject of numerous embodiments. In a manner known per se, it may for example be a bundle of electrically conductive wires insulated from one another, or preferably a printed circuit or a flexible plastic film provided with several parallel metallized tracks.

 The ends of the flexible conductor 300 are respectively connected to electrical contacts placed in connector bodies provided on the housing elements 100, 200, or else the ends of the flexible conductor 300 pass through and are supported by these housing elements 100, 200 for be connected to external peripheral members such as, for example, a protective bag inflation system such as an airbag and means for controlling such a system.

 In the appended figures, the relative axis of rotation of the housing elements 100, 200 is referenced SO.

 The intermediate element 400 is placed between the housing elements 100, 200. The intermediate element 400 is freely movable relative to the housing elements 100, 200, that is to say that unlike certain contactors previously proposed, such as described for example in documents FR-A-2665805 and US-A-5046951, the intermediate element 400 is not connected to the housing elements 100, 200 by at least one drive pinion defining a predetermined and imposed displacement ratio between the intermediate element 400 and said housing elements 100, 200.

 In other words, the intermediate element 400 is simply guided in rotation about the aforementioned axis GO, between the housing elements 100 and 200.

 As can be seen in the appended figures, the intermediate element 400 defined in combination with the central housing element 200, an auxiliary chamber 402. According to the invention, this chamber 402 is adapted to receive a variable number of turns of the conductive member 300 corresponding to a substantially constant length of this member, depending on whether these turns are pressed against said intermediate element, or against the associated housing element 200 defining the auxiliary chamber, during a relative movement by rotation of the two elements housing 100, 200, without appreciable relative rotation between said intermediate element 400 and the other housing element 100.

 Furthermore, as can be seen in the appended figures, according to the invention, the flexible conductive member 300 is curved in a loop on the intermediate element 400. As a result, the winding directions of the conductive member 300 in the auxiliary chamber 402 (clockwise towards the center of rotation 0-0) is opposite to the winding direction of the same conductive member 300 on the outside of the intermediate member 400 (clockwise shows away from the center of rotation 00).

 More specifically, according to the preferred embodiment of the invention shown in the accompanying figures, the auxiliary chamber 402 has a cross section in the general shape of a crescent.

 To this end, the intermediate element 400 is defined mainly by two cylindrical walls 410, 420, of different radius.

 The external cylindrical wall 410 is centered on the axis of rotation O-O. On the other hand, the internal cylindrical wall 420 of lower radius is eccentric relative to the axis of rotation SO. The two walls 410, 420 are joined tangentially. The auxiliary chamber 402 is defined between the internal cylindrical wall 420 and the cylindrical rotor of the housing element 200.

 In its zone 430 diametrically opposite to the zone 422 of connection between the walls 410, 420, the intermediate element 400 has a through opening 432, of generally radial orientation relative to the axis of rotation O-O.

 More precisely, this opening 432 is preferably curved, for example in the form of a semi-cylindrical sector, to be tangentially connected respectively to the internal surface of the wall 420 and to the external surface of the wall 410.

 The curved shape of the opening 432 in which the conductive member 300 is engaged and at the level of which the flexible conductive member is curved in a loop as indicated previously, is designed to avoid injuring this conductor 300.

 In addition, as can be seen in the appended figures, the housing element 200 which defines the auxiliary chamber 402 in combination with the intermediate element 400 carries a tongue 500 capable of pivoting.

 The tongue 500 is made of an at least semi-ridiculous material. It is advantageously plastic.

 The tongue 500 is pivotally mounted on the housing element 200 around an axis 502 parallel to the axis O-O of pivoting of the contactor. The tongue 500 extends in a general direction transverse to the axis OO.

 More precisely still, the tongue 500 is pivotally mounted on the element 200 in the vicinity of one of its ends.

 The tongue 500 is placed opposite a housing 220 formed in a generally annular crown 210 of the element 200. The tongue 500 has a generally curved shape concave towards the center GO of the contactor.

 Furthermore, the tongue 500 is tapered towards its free end opposite the pivot axis 502. Its main surfaces 504, 506 respectively external and internal are delimited by generatrices parallel to the axis O-O. These main surfaces 504, 506 converge towards the free end of the tongue 500. The external surface 504 of the tongue 500 is preferably generally cylindrical of revolution with a radius of curvature identical to that of the external surface of the crown 210 .

 The internal surface 506 of the tongue is also preferably generally cylindrical of revolution, with a radius of curvature less than that of the external surface 504. The internal surface 506 is advantageously complementary to the surface 222 of the crown 210 defining the bottom of the housing 220.

 As can be seen in the appended figures, the region of the conductive tape 300 adjacent to its radially internal end fixed to the element 200 passes between said surface 222 defining the bottom of the housing 220 and the internal surface 506 of the tongue 500.

 Furthermore, as can be seen on examining the appended figures, the free end 510 of the tongue 500 is radiated, that is to say that its external surface 504 curves gradually with a decreasing radius in proximity to the free end.

 According to the embodiment illustrated in the appended figures, the tongue 500 covers an angular opening around the axis O-O of rotation of the contactor of the order of 60.

 Furthermore, the tongue 500 extends counterclockwise from its pivot axis 502, according to the arbitrary representation given in the appended figures.

 As indicated above, the tab 500 is designed to alternately occupy two positions: a) a first position illustrated in FIG. 1 in which the tab 500 is retracted into the housing 220, obtained when the contactor is driven in one direction which tends to press the conductive tape 300 against the element 200, that is to say a rotation of the element 200 clockwise> and b) a second position illustrated in FIG. 2 in which the tongue 500 extends across the auxiliary chamber 402, between the element 200 and the intermediate element 400 obtained when the contactor is driven in the opposite direction, that is to say for a rotation of the element 200 counterclockwise.

 The operation of the contactor which has just been described is essentially as follows.

 During a significant rotation of the central box element 200 (linked for example to the steering wheel of the vehicle) clockwise> the conductive tape 300 leaves the outer chamber formed between the outer surface of the element intermediate 400 and the internal surface of the housing element 100, to wrap around the outside diameter of the housing element 200.

 During this maneuver, the conductive tape 300 undergoes a stress when passing through the opening 432. The intermediate element 400 is therefore rotated by the conductive tape 300 concentrically with the axis GO.

 In this position, the tongue 500 is pressed into the retracted position in the housing 220. Its external surface 504 defined with the external surface of the crown 210 a continuous diameter and not injurious to the ribbon 300.

 During a rotation in the opposite direction, that is to say a rotation of the housing element 200 anticlockwise, the radius of curvature of the opening 432 generates a stress on the ribbon 300 which requires a certain torque for driving the intermediate element 400.

 The free part of the ribbon 300 wound around the outside diameter of the case element 200 can then take place towards the internal surface of the intermediate element 400, as shown diagrammatically in FIG. 2.

 During this movement, the portion of the tape 300 placed in the housing 220 biases the internal surface 506 of the tongue 500 radially outward. The ribbon 300 thus causes the rotation of the tongue 500 around the axis 502 in the second position, until the free end of the tongue 500 comes to rest against a turn of the ribbon 300 adjacent to the internal surface of the intermediate element 400.

 When the central housing element 200 is again moved clockwise, the conductive tape 300 is again wound in turns of smaller radius on the outer surface of the housing element 200 and FIG. 500 is returned to the retracted position as shown in FIG. 1.

 On the other hand, when the turns of the ribbon housed in the auxiliary chamber 402 are pressed entirely against the internal surface of the intermediate element 400 and when the rotation of the housing element 200 is continued counter-clockwise , the tape 300 is pressed against the concave surface 433 of the opening 432. The conductive tape 300 then drives the intermediate element 400 anticlockwise, and the conductive tape 300 leaves the auxiliary chamber 402 and takes place between the outer surface of the intermediate element 400 and the inner surface of the housing element 100. During this maneuver, the strip 300 again undergoes stress in the opening 432, more precisely on the concave surface 433 of this one.

 During this last movement, the tongue 500 is again placed in the second position, that is to say transversely to the auxiliary chamber 402 as illustrated in FIG. 2.

 It will be noted that the internal surface 506 of the tongue 500 forms in the second position (FIG. 2), in combination with the internal surface of the intermediate element 400 a continuous connection zone which allows the ribbon 300 to form a natural, non-injurious winding.

In addition, the free end of the tongue 500 slides without difficulty on the strip 300 or the internal face of the intermediate element 400, thanks to its radiated geometry, although the inclination of the tongue 500 relative to the internal surface of the intermediate element 400 varies during the rotation of the element 200 due to the eccentricity of the auxiliary chamber 402.

 Those skilled in the art will understand that in the second deployed position, the tongue 500 serves to support the ribbon 300 and stiffens it.

It thus prevents the ribbon 300 from turning over on itself in the auxiliary chamber 402 when the element 200 is driven in a counter-clockwise direction.

 In the context of the present invention, the auxiliary chamber 402 is preferably dimensioned to receive a length of conductive tape 300 corresponding to approximately 80% of the relative displacements required for use between the housing elements 100, 200 without causing displacement of the intermediate element 400.

 Those skilled in the art will understand that the rotary electrical contactor which has just been described makes it possible to use shorter lengths of tape compared to the devices previously proposed.

 In fact, the rotary electrical contactor allows the ribbon 300 of short length to be used in two specific configurations depending on the angular travel of the device.

 The first configuration corresponds to short deflections, typically a relative rotation between the housing elements 100, 200 less than one revolution. In this first configuration, the ribbon is unwound from the outside diameter of the central housing element 200 towards the internal surface of the intermediate element 400 and vice versa as shown in FIGS. 1 and 2. Due to the limited use of this principle of loosening and tightening of the turns in a chamber, as for the angular travel required, the rotary electrical contactor requires only a reduced length of conductive tape 300 compared to previous devices which require such loosening and tightening of the turns of the strip 300 for the entire authorized relative rotation range between the housing elements 100 and 200.

 The second operating configuration of the contactor according to the invention corresponds to an entire travel, that is to say to a relative rotation between the housing elements 100, 200 over the maximum authorized range. In the context of this configuration, the reversal of the strip 300 is used in the opening 432 of the intermediate element 400. As has been demonstrated previously, this reversal makes it possible to limit the length of the strip 300 relative to the contactors in which the ribbon 300 is shaped in a single spiral without turning.

 The present invention therefore offers many advantages over prior art rotary electrical contactors.

 It allows in particular to use a ribbon 300 of shortened length while limiting the stresses applied to the ribbon 300. In fact, in 80% of the operation of the contactor, the ribbon 300 is not moved relative to the opening 432 of the 'intermediate element 400 and therefore does not undergo any particular constraint.

 Of course the present invention is not limited to the particular embodiment which has just been described but extends to any variant in accordance with its spirit.

 In particular, the invention could easily be transposed to a variant according to which the auxiliary chamber 402 is formed not on the interior of the intermediate element 400 but on the exterior thereof, that is to say between the exterior surface of the intermediate element 400 and the internal surface of the housing element 100. In this case, the tongue 500 is pivotally carried by this housing element 100.

 Preferably in the midpoint position of the contactor, the length of flexible conductive member 300 placed in the auxiliary chamber 402 is of the order of half the total length of this member 300.

 The rotary electrical switch described above has an eccentric auxiliary chamber 402. When the flexible conductor 300 is pressed against the internal surface of the cylindrical wall 420 of the intermediate element 400, it applies a tilting torque on the latter causing an bracing of this intermediate element. In addition, in use, a first resistant torque occurs due to the friction of the turns of the flexible conductor 300 between them and a resistant torque due to the friction of the intermediate element 400 relative to the elements 100, 200 of the housing.

 To improve this contactor, provision may be made to guide the intermediate element 400 on the movable element 200. This guidance can be produced, for example, in the form of an annular rib 440 formed at the periphery on the intermediate element 400, which rib 440 is engaged in a complementary groove of the movable element 200.

 Thus, the movable element 200 tends to drive the intermediate element 400 which eliminates the torque due to the bracing.

 Furthermore, stops may be provided, on the rotary electrical contactor, between the fixed element 100 and the movable element 200, or even between the intermediate element 400 and one of these elements 100 or 200, to limit the authorized angle of rotation, for example and not limited to five turns, between the elements 100 and 200.

 In this context, two extreme configurations authorized for the flexible conductive member 300 can be provided: one in which the flexible conductive member is completely wound, in the form of coils tightened on the central element 200 of the auxiliary chamber 402 and the other in which the flexible conductive member 300 is integrally disposed in the chamber between the intermediate element 400 and the external member 100.

 However, it can also be provided that, in the second configuration, corresponding to an extreme position authorized by the mechanical stops, there remains a certain length of conductive tape 300 in the auxiliary chamber 402. This arrangement makes it possible to increase the angular clearance authorized between elements 100 and 200, without displacement of the intermediate element 400, by simple variation of the mean diameter of the turns in the auxiliary chamber 402. In other words, this arrangement makes it possible to increase the angular operating range of the contactor, without displacement of the flexible conductive member 300 in the passage 432.

Claims (23)

 1. Rotary electrical contactor of the known type comprising two housing elements (100, 200) capable of relative rotation, a flexible conducting member (300) placed between these two elements (100, 200), an intermediate element (400) placed between the two housing elements (100, 200) freely movable relative thereto, and the flexible conductive member (300) being curved in a loop on the intermediate element (400), characterized in that the intermediate element ( > 100) defines an auxiliary chamber (402) between itself and one of the housing elements, adapted to receive a variable number of turns of the flexible conductive member (300) corresponding to a substantially constant length of this member, depending on whether these turns are pressed against said intermediate element (400) or said housing element (200) associated and defining the auxiliary chamber (402), during a relative rotation movement of the two housing elements ( 100, 200) without significant relative rotation between said intermediate element (400) and the other housing element (100), and by the fact that said housing element (200) defining the auxiliary chamber (402) in combination with the intermediate element (400), is equipped with a tongue (500) capable of pivoting between a first retracted position on said housing element (200) when the contactor is driven in a direction which tends to press said conductive member (300) against this element (200), and a second position in which said tab (500) extends across the auxiliary chamber (402), between said housing element (200) and the intermediate element (400) when the contactor is driven in an opposite direction.  2. Contactor according to claim 1, characterized in that the tongue (500) is at least semi-rigid.  3. Contactor according to one of claims 1 or 2, characterized in that the pivot axis (502) of the tongue (500) is parallel to the axis GO of rotation of the contactor.  4. Contactor according to one of claims 1 to 3, characterized in that the tongue (500) is rotatably mounted at one of its ends.  5. Contactor according to one of claims 1 to 4, characterized in that the tongue (500) is placed opposite a housing (220) formed in a crown (210) of the housing element (200) defining the auxiliary chamber (402) and by the fact that the external surface (504) of the tongue (500) is cylindrical of revolution complementary to the external surface of said crown, while the internal surface (506) of the tongue (500 ) is complementary to the bottom of the housing (220).  6. Contactor according to one of claims 1 to 5, characterized in that the external surface (504) of the tongue (500) has a variable radius decreasing in the direction of its free end.  7. Contactor according to one of claims 1 to 6, characterized in that the flexible conductive member (300) passes between the tongue (500) and the element (200) of the housing which carries the latter pivotally.  8. Contactor according to one of claims 1 to 7, characterized in that the tongue (500) covers an angular opening of the order of 60O relative to the axis of rotation of the contactor.  9. Contactor according to one of claims 1 to 8, characterized in that the auxiliary chamber (402) is a chamber internal to the intermediate element (400) defined between the intermediate element (400) and a central element ( 200) making up one of the two housing elements.  10. Contactor according to one of claims 1 to 8, characterized in that the auxiliary chamber (402) is a chamber external to the intermediate element (400) defined between the intermediate element (400) and an external element ( 100) making up one of the two housing elements.  11. Contactor according to one of claims 1 to 10, characterized in that the auxiliary chamber (402) is defined between the intermediate element (400) and the housing element (200) movable in rotation.  12. Contactor according to one of claims 1 to 11, characterized in that the intermediate element (400) is defined by two eccentric cylindrical walls (410, 420).  13. Contactor according to claim 12, characterized in that one of the external cylindrical walls (410) is centered on the axis of rotation (OO) of the contactor, while the other cylindrical wall (420), internal, is eccentric with respect to this axis of rotation (OO).  14. Contactor according to one of claims 12 or 13, characterized in that the two cylindrical walls (410, 420) are connected tangentially.  15. Contactor according to one of claims 1 to 14, characterized in that the intermediate element (400) has a generally radial transverse opening (432).  16. Contactor according to claim 15, characterized in that the opening (432) is curved, for example in the cylinder sector.  17. Contactor according to one of claims 1 to 16, characterized in that the auxiliary chamber (402) is in the general shape of a crescent.  18. Contactor according to one of claims 1 to 17, characterized in that the auxiliary chamber (402) is dimensioned to receive a length of ribbon (300) allowing a relative movement in rotation between the two housing elements (100, 200), approximately over 80% of the operation of the contactor, without imposing relative displacements of the intermediate element (400).  19. Contactor according to one of claims 1 to 18, characterized in that the intermediate element (400) is guided by the movable element (100).  20. Contactor according to claim 19, characterized in that the guiding of the intermediate element (400) on the movable element (100) is obtained by the engagement of a rib (440) in a complementary annular groove provided on these items.  21. Contactor according to one of claims 1 to 20, characterized in that there are stops provided between the fixed element (100) and the movable element (700), or even between the intermediate element (400) and one of these elements (100 or 200), to limit the authorized angle of rotation, for example and not limitatively to five turns, between the elements (100 and 200).  22. Contactor according to one of claims 1 to 21, characterized in that it is adapted to define two extreme configurations authorized for the flexible conductive member (300): one in which the flexible conductive member is fully wound, in the form of tight turns on the element of the housing (200) which defines the auxiliary chamber (402) and the other in which the flexible conductive member (300) is integrally disposed between the intermediate element (400) and the other element (100) of the housing.  23. Contactor according to one of claims 1 to 21, characterized in that it is adapted to define two extreme configurations authorized for the flexible conductive member (300): one in which the flexible conductive member is fully wound, in the form of tight turns on the element of the housing (200) which defines the auxiliary chamber (402) and the other in which the flexible conductive member (300) is partly disposed between the intermediate element (400) and the other element (100) of the housing, and partly arranged in the auxiliary chamber (402).