FR2691587A1 - Rotating contactor mountable between steering column and steering wheel of road vehicle - uses conducting wire wound on conducting drum, tension and frictional force of which is controlled to provide reliable contact with non-rotating part of device - Google Patents

Abstract

The contactor consists of a fixed part (2) with at least one input track (6,10) and a moving part (1,3) with at least one output track (32,33) and an electrical friction contact device (4,8). One part of the contact device consists of an electrically conducting drum (4) connected to the output track and fixed to the rotating part. The other part consists of a flexible electrical wire (8) held by a tensioning device by being wound on the drum. It is connected to a rigid piece (6) carried by the fixed part and belonging to the input track and creates a band friction device of controlled tightness. ADVANTAGE - Eliminates problems of existing designs such as limited number of turns of steering wheel, fragility particularly at low temperatures and restricted number of tracks.

Description

 The present invention relates to a rotary switch, in particular for mounting between the steering column and the steering wheel of a motor vehicle, comprising a fixed part with at least one input channel, a movable part with at least one output channel and a electrical connection device with rubbing contact interposed between said input and output channels for transmitting and / or receiving electrical information.

 In the context of a motor vehicle, a rotary switch is intended in particular to be mounted (FIG. 1) between the steering column 101 and the steering wheel 100 of the vehicle and the information can be of several types for controlling in particular the horn, vehicle speed control, remote control of a car radio and airbag security systems such as "Air-Bag" or "Euro-Bag".

 For simplification in the description, the channel associated with the mobile part will be called the output channel, while the channel associated with the fixed part will be called the input channel. These channels include connectors and electrical connecting wires.

 Thus the rotary switch 104,105 makes it possible to transmit and / or receive electrical information between a first member 106 placed on the steering wheel and a second associated member 107 placed on the vehicle, for example the horn and its associated switch or a safety device. bag and its associated shock sensor.

 The contactor comprises a movable part 105 secured to the steering wheel 100 of the vehicle and a fixed part 104, such as a switch support, secured to a fixed part 102 of the steering column 101, of which the transmission shaft 103 is secured of the steering wheel.

 In FIG. 1, the fixed part 104 comprises pistons establishing, by friction, an electrical contact on electrical tracks of the mobile part 105.

 This arrangement is simple because it has no mechanical connection with the steering wheel and the electrical switching is carried out automatically when the steering wheel is fitted.

 However, the number of transmissible information is limited because the number of tracks and electrical connection is reduced with a single electrical contact point per track. In addition, there are risks of micro-cuts under the effect of vibrations and the space requirement is significant. In addition, the electrical connection is made by independent wires.

 To reduce the size, and increase the number of tracks and electrical connection, one can consider using a provision of that described for example in document FR-A-2 604 129.

 In this, the rotary switch, also called the electrical transmission ring, comprises a friction washer system, some being held fixed relative to the steering column, the others being driven by the steering wheel.

 These conductive washers are coupled in pairs (one fixed, the other mobile). Each pair of washers is isolated from the previous pair, thus allowing a multiplicity of electrical contacts.

 It is thus possible to obtain up to nine contacts and to make double contacts.

 The torque is low and is compatible with the application requested. This device incorporates the indicator recall sector and allows electrical connection to connectors with a large number of channels.

 The rotation of the mobile part relative to the fixed part is not limited to a determined number of turns. However, such a device uses a large number of parts and the number of contact points per track is limited (six per washer).

 The contact pressure is produced by six springs for all of the washers and is therefore very low per point of contact. In addition, the flatness of all of the washers is not satisfactorily ensured, there is a risk of micro-cuts due to this flatness and to the low contact pressure.

 To overcome this drawback, one can consider using an arrangement with a ribbon winding and unwinding between a hub driven by the steering wheel and a housing maintained by the steering column.

Such an arrangement is described for example in documents EP-AO 479 568 and EP-AO 479 567. It has advantages namely
- guaranteed electrical continuity (no risk of micro-cuts)
- a very low operating torque limited to the friction of the parts of the rotating mechanism
- it integrates the indicator reminder sector
- it allows electrical connections on connectors with large numbers of channels.

 However, the rotation is limited to a determined number of turns and the number of tracks is limited by the size.

 In addition, it is relatively fragile, particularly at low temperatures, because it uses copper electrical tracks mounted on an insulating support and the electrical resistance of the entire device, the section of the conductor and the length of the tape ( about 0.5 Ohms for a section of 2mm x 0.035mm and a length of 2m).

 In addition, there is an obligation to preposition the movable part relative to the fixed part during assembly and there is a risk of noise from the device under the effect of vibrations due to the movement of the ribbon in its housing.

 The object of the present invention is to overcome the drawbacks of the provisions of the prior art in a simple and economical manner while retaining their advantages.

 According to the invention a rotary contactor of the above-mentioned type is characterized in that the electrical connection device comprises at least, on the one hand, an electrically conductive part with a drum connected to the outlet channel and integral in rotation with the part mobile, and, on the other hand, a flexible electrically conductive wire stretched by a tensioning device being wound on the drum of the drum piece and connected to a rigid piece carried by the fixed part and belonging to the entry way , so as to create a band friction device with controlled tightening tension.

 Thanks to the invention, the size of the contactor is reduced and no particular pre-orientation is not imposed during assembly. Indeed, the orientation necessary for mounting the steering wheel on the vehicle can be given by the connector that advantageously comprises the movable part, as well as by drive pins which are inserted in the foaming of the steering wheel.

 In addition, the number of rotational turns of the movable part is not limited and continuity of the electrical contacts is guaranteed with a constant and appropriate contact pressure per channel or element thanks in particular to the tensioning device.

 The torque necessary for the rotation of the movable part is thus very suitable. No contact bounce is to be feared.

 This device also makes it possible to double the number of contact elements if necessary in order to avoid micro-cuts and makes it possible to integrate the sector for recalling the turn signals.

 The flexible wire ensures a linear contact on a circular sector thus guaranteeing a significant electrical continuity due to the winding of the wire on its drum.

 In one embodiment, the drum part consists of a metal cup and the apparatus is produced by a set of cups and washers electrically insulated and tightened together thanks in particular to the assembly of a central hub with a molded cover. , which comprises the movable part of said contactor. This integral assembly is rotated by the flywheel.

 On each of these cups is stretched one (or two for safety reasons) special wire, at the ends of which are made extension springs advantageously in the form of coil springs.

 As a variant, these extension springs can consist of elastic blocks, for example blocks of elastomeric material. The tension of these springs is determined to, depending on the applications, ensure and guarantee the contact pressure, electrical continuity, as well as the torque.

 Each end of the springs of these elastic wires is hooked to the rigid part, advantageously in the form of an electrically conductive rigid support, itself held fixed to the fixed part of the rotary switch supported by the vehicle steering column.

 The electrical connections are easy and are made by the accessible sides for example by welding.

The following description illustrates the invention with reference to the accompanying drawings, without which
FIG. 1 is a schematic view of a rotary switch according to the prior art mounted between the steering column and the steering wheel of the motor vehicle,
FIG. 2 is a view in axial section of a rotary contactor according to the invention,
FIG. 3 is a sectional view along line 3-3 of FIG. 2,
FIGS. 4 and 5 are views respectively according to arrows 4 and 5 in FIG. 2,
FIG. 6 is a schematic exploded view of a spring wire and of its associated cup according to the invention,
FIG. 7 is an enlarged view of part of FIG. 2 materialized by the insert 7 thereof,
FIG. 8 is a perspective view of the rigid part according to the invention,
FIG. 9 is a view similar to FIG. 8 for a second exemplary embodiment,
FIG. 10 is a view similar to FIG. 6 for another exemplary embodiment,
FIG. 11 is a schematic view of the switch in FIG. 10 mounted with the flexible wire mounted on the fixed part,
- Figure 12 is a schematic view similar to Figure 11 for yet another embodiment of the invention.

 In FIGS. 2 to 12, a rotary switch intended to be mounted between the steering column and the steering wheel of a motor vehicle is illustrated in place of the parts 104 and 105 of FIG. 1. This contactor comprises a fixed part 2 with at least one input channel 6,7,10, a movable part 1,3 with at least one output channel 32,33 and an electrical connection device 4,8 with friction contact interposed between said input channels and output to transmit and / or receive electrical information.

 According to the invention, a rotary contactor of the above-mentioned type is characterized in that the electrical connection device 4,8 comprises at least, on the one hand, an electrically conductive part with a drum 4 connected to the output channel 32, 33 and integral in rotation with the movable part 1,3, and, on the other hand, a flexible electrically conductive wire 8 stretched by a tensioning device 85,185,285 by being rolled on the drum of the drum piece 4 and connected to a piece rigid 6,7 carried by the fixed part and belonging to the entry path 6,7,10, so as to create a friction device with band and controlled tightening tension.

 Here the clamping voltage is determined to ensure and guarantee the contact pressure between said flexible wire 8 and the drum of the part 4, as well as to guarantee electrical continuity and the torque, said contact pressure being compatible with the torque drive. The rigid part 6,7 is held by the fixed part.

 In Figures 2 to 8, the part 4 consists of a stamped metal cup and electrically conductive. Here there are two cups 4 separated from each other by an electrically insulating washer 5 and the set of cups 4 - washer 5 is locked in rotation on a central hub 1 of the movable part, by a connection to cooperation of forms.

 This connection comprises lugs 42, 43, belonging respectively to said cups 4 and to washer 5, engaged in an axial groove 44 and 46 of hub 1 respectively.

 Each cup 4 by definition comprising a tubular portion (the drum) mounted here on the outer periphery of the hub 1 and a bottom, the lugs 42 project radially inward from a single piece of said bottom.

 The contactor comprises a central hub 1, a housing 2 and a molded cover 3, all made of electrically insulating material, here plastic.

 The hub 1 is disposed in the center of the housing 2, the bottom 20 of which is perforated for passage of the hub 1, which has, at its end adjacent to the bottom 20, a flange 30 forming a shoulder for support on the transverse face of the bottom 20 turned towards the opposite the cover and hollowed out for penetration of the collar 30.

 The hub 1 is therefore mounted journalled relative to the bottom 20 while being axially wedged by its flange 30 bearing on the bottom 20. This hub 1 is assembled to the cover 3 to be secured, here by screws 9, alternatively by bolting or riveting , or collage.

Here three screws regularly distributed circularly are provided and the cover 3 has a central axial sleeve 40 surrounded by the hub 1 for centering with respect to the hub 1.

 The sleeve 40 is notched at 52.36 for the formation of three areas 50 and passage of three corresponding internal lugs 51 of the hub 1. The lugs 51 are tapped and the areas 50 are perforated for mounting the screws 9.

 This arrangement therefore makes it possible to block the hub 1 in rotation relative to the cover 3 and to tighten the washers 5 and the cups 4.

 The hub 1 and the cover 3 belong to the movable part, said cover being provided, on its face turned away from the housing 2, with three pins 31, regularly distributed circularly, which are intended to be inserted into the foaming of the flywheel for driving the moving part 3.1 in rotation by the flywheel. The cover 3 also has a connector 32 belonging to the outlet channel.

 The housing 2 belongs to the fixed part and is crossed, like the hub 1 and the cover 3, by the shaft 103 of FIG. 1.

 Thus, no particular pre-orientation is to be carried out during assembly.

 The electrically insulating central hub 1 is stepped and has the grooves 44 and the grooves 46 emerging at the level of the cover 3 and located radially below the grooves 44, these grooves 46 therefore consist of recesses or notches.

 In a position diametrically opposite to the recess 46, the hub 1 also has, for each cup 4, a recess 45, similar to the recess 46, for passage of a tail 41, of the cup 4.

 All these provisions allow mounting by axial threading of two electrical insulation washers 5 and two electrically conductive cups 4.

 Thus Figure 7 is obtained in axial succession, going from the flange 30 to the cover 3, the following arrangement - first washer 5 - first cup 4 - second washer 5 - second cup 5 in contact with a shoulder 87 of the cover 3. L the set of washers 5 and cups 4 is therefore clamped between the shoulder 87 and the shoulder of the hub 1 formed by the bottom of the grooves 44.

 Each washer 5 (FIG. 7) has lugs 43 which are engaged in a complementary manner in the grooves 44 and a trapezoidal head, the first cup 4 forming an axial spacer between the two washers 5, while the second cup 4 forms an axial spacer between the shoulder 87 and the second washer 5.

 The shoulder 87 is formed by means of an additional thickness 89 having an inclined profile, so that two flared grooves of trapezoidal shape are created respectively between the two washers 5 and between the second washer 5 and said additional thickness 89. These grooves spare the wires 8 in operation.

 Each cup 4 has a tab 42 engaged in the notch 46, as well as a united tail 41 engaged axially in the notch 45 and passing through connections 33 molded onto the cover 3.

 These electrically conductive connections 33 are made of brass, like the contact cups 4, and include tongues of axial orientation belonging to the connector 32 and to the outlet channel. These connections 33 (FIG. 4) are split by presenting internally inclined parts with holes and crossed by the tails 41 with here tin welding of said tails on said inclined parts.

 To do this, the cover 3 has passages 35 at this location (Figure 4). I1 also presents the passages or notches 36 for access to the screw heads 9. Here everything is split for safety reasons and to avoid micro-cuts. The entry path comprises two rigid parts 6,7 in the form of a crown portion (FIG. 5). These parts 6,7 are accessible from the outside on the side of the face of the housing 2 facing away from the cover 3 while being brought to attachment by the housing 2.

 To this end, the bottom 20 has recesses 93 of annular shape. Each ring 6,7 has two latching tabs 80 directed axially towards the cover 3 and passing through the bottom 20 of the housing with anchoring. This housing 2 has three fixing lugs 19 distributed regularly circumferentially for fixing by screws on the support of the switches located at the fixed part of the steering column.

 The cover 3 has a sector 37 for recalling the turn signals. The switch holder carries the turn signal switch.

 On these rings 6,7, identical to each other, are welded and crimped with electrical supply wires 10 belonging to the entry channel. This fixing is carried out using a tongue 81 that each crown has.

 Each tongue 81 has a hole 83 delimited by a chimney for the passage and welding of the wire 10 and carries at the end a circular conformation 82 for crimping the sheath of the wire 10.

 As shown in Figure 5, the two tabs 81 are adjacent, one having been cut to show the hole 83, the son 10 being removed. The electrically insulating housing 2 is notched for this purpose, the tongues 81 comprising folded parts extending axially in the opposite direction relative to the tongues 80. These tongues 80 have notches for hooking the wires 8 in the manner described below.

 Here the tensioning device comprises at least one elastic member 85 acting on the flexible wire 8 while being carried by the fixed part 2, so that said wire 8 bears on a circular sector of the cup while being stretched by said elastic member.

 The wire 8 is based on bronze and has its two ends 8 hung on the same tongue 80 forming a hooking part. This wire 8 is supported in the vicinity of each of its ends on a protuberance 21 of axial orientation (Figure 3) secured to the housing 2 here by molding. The protrusions 21 therefore make it possible to tension the wire 8 in contact with the cup 4 while being arranged radially on a circumference of diameter greater than that of the cups 4.

 Each tongue 80 is framed by two protuberances 21 whose external periphery is of curved shape for winding the wires 8.

 Here two wires 8 are mounted on each cup 4 and the arrangement of these wires 8 is defined in order to balance the tensions of the cups 4.

 More precisely as can be seen in FIG. 3, four tongues 80 distributed regularly circumferentially, being located on the same circumference, are provided and these tongues are used for the attachment of the four wires 8. Each tongue 80 alternates circumferentially with a protuberance 21 also distributed regularly circumferentially.

 Thus the tongues 80 are diametrically opposite, just like the protuberances 21, so that a balanced arrangement is obtained with each wire winding generally over 1800 on the cup 4, then on two protuberances 21 to hang on the tongue 80 concerned.

 Each wire 8 constitutes a spring wire and has a central part 84 in the form of a wire, each end of the wire 84 being shaped as a helical spring 85 with a straightened end turn 86 in the form of a band to hang on the tongue 80. concerned (on its notches).

 During assembly the springs 85 are prestressed so that there is continuity when passing through the equilibrium position, one of the springs relaxing while the other compresses according to the direction of rotation of the part. mobile 1.3.

 The turns 86 are soldered here in tin on the tabs 80.

 Thus the assembly is carried out in a simple manner by threading and one proceeds in the end to a screwing of the cover 3 with the hub 1, the last operation consisting in soldering with tin the tails 41 of the contact cups 4 on the connections. 33 in the area reserved for this purpose, here in the upper part.

 Thus on the steering column side, the inlet channel comprises a two-way connector with wires 10 welded to the crowns 6,7, while on the steering wheel side the outlet channel comprises a two-way connector 32 integrated into the cover 3 by molding.

 It will be appreciated that one can perform any number of turns of the part 1.3 relative to the fixed part 2, while having good electrical continuity and without risk of rebound.

 Of course, the present invention is not limited to the embodiment described. In particular, the crowns 6,7 may have a tongue 181 (FIG. 8) shaped to belong to a connector similar to the connector 32 and be mounted on the field in the housing 2 (see FIG. 9) therefore without bending with tongues 180,281. The exit route may include wires.

 The tensioning device may comprise only one spring while being carried by the fixed part. Thus in FIGS. 10 to 11 the flexible wire 8 has two ends 186 in the form of a loop connected to each other by a wire 184 coming to be wound on the cup 4. The wire 184 is subjected to the action of 'a spring 185 and is wound on protrusions 121 of the housing 2. Thus when the flywheel is rotated, the spring 185 is stretched and relaxed which, due to the protrusions 181, performs controlled tightening for the wire 8.

 In Figure 12 the wire 284 has its two ends 286 subjected to the action of a spring 285 bearing on a fixed part 287 of the housing 2 and on the ends 286 whose movement is guided by a conformation of the housing 2. Thus we stretch the wire 284.

 As a variant, the tensioning device could include a weight device or an electromagnetic device making it possible to tension the thread.

 Each end of the wire 8 can come to hang on a specific attachment part, the two attachment parts being framed by two protuberances.

 Likewise, only one wire can be provided per drum and the number of input and output channels can be multiplied. The contactor may have a single cup and a single wire with a single input and output channel. However, it will be appreciated that the arrangement of the figures described above is advantageous in particular in the context of the control of an airbag.

 Indeed, the splitting of the electrical connections and their mounting in parallel leads to a safe and flawless operation of the rotary contactor.

 In the event of an impact, the sensor mounted on the vehicle sends information through the rotary switch which enables the airbag to be triggered.

Claims (12)

 1) Rotary switch, in particular for mounting between the steering column and the steering wheel of a motor vehicle comprising a fixed part (2) with at least one input channel (6,7,10), a mobile part (1, 3) with at least one output channel (32,33) and an electrical connection device (4,8) with friction contact interposed between said input and output channels for transmitting and / or receiving electrical information, characterized in that the electrical connection device (4,8) comprises at least, on the one hand, an electrically conductive part with a drum (4) connected to the outlet channel (32,33) and integral in rotation with the movable part ( 1,3), and, on the other hand, a flexible electrically conductive wire (8) stretched by a tensioning device (85,185,285) by being rolled on the drum of the drum piece (4) and connected to a rigid piece ( 6,7) carried by the fixed part and belonging to the entry path (6,7,10) so as to create a device belt friction and controlled clamping tension.  2) Contactor according to claim 1, in which the mobile part (1,3) comprises a central hub (1) made of electrically insulating material, characterized in that the drum part (4) consists of a cup made of electrically conductive material ( 4) locked in rotation on the central hub (1).  3) Contactor according to claim 2, characterized in that the tensioning device (85,185,285) comprises at least one elastic member (85,185,285) acting on said flexible wire (8) being carried by the fixed part (2), so that said wire (8) bears on a circular sector of the cup (4) while being stretched by said elastic member.  4) Contactor according to claim 2, characterized in that the wire (8) is also supported on two protrusions (21,121) secured to a housing (2) of electrically insulating material belonging to the fixed part (2) of said contactor.  5) Contactor according to claim 3 or 4, characterized in that the flexible wire (8) consists of a spring wire secured at each of its ends to an elastic member (85) hung on the rigid part (6,7) carried by the fixed part (2).  6) Contactor according to claim 5, characterized in that the rigid part (6,7) consists of a rigid support (6,7) in the form of a crown portion with at least one tongue of axial orientation (80), that the elastic members (85) consist of helical springs (85) forming the ends of the flexible wire (8), and that said helical springs (85) comprise an end turn (86) in the form of an attached loop on said tongue (80), so that the helical springs (85) work in opposition.  7) Contactor according to claim 6, characterized in that it comprises two flexible wires (8) electrically conductive wound on the cup (4), each being hung on a tongue (80) belonging to a rigid support (6,7) , and in that the tongues (80) are diametrically opposed and belong to rigid supports (6,7) distinct from each other.  8) Contactor according to claim 7, characterized in that each flexible wire is wound on the cup (4) and on two protrusions (21) integral with the housing (2) belonging to the fixed part (2), the two protrusions ( 21) framing the tongue (80) concerned.  9) Contactor according to any one of claims 2 to 8, characterized in that it comprises at least two cups (4) separated from each other by an electrically insulating washer (5), and in that said cups (4) and the electrically insulating washer (5) are locked in rotation on the central hub (1) by a form-fitting connection.  10) Contactor according to claim 9, characterized in that it comprises in axial succession, mounted on the central hub (1), a first electrically insulating washer, a first cup (4), a second insulating washer (5) and a second cup (4), said assembly being axially wedged between a shoulder belonging to the central hub (1) and a shoulder (87) belonging to a cover (3) that comprises the movable part (1,3).  11) Contactor according to claim 10, characterized in that the shoulder (87) of the cover (3) is formed by means of an extra thickness (89) having an inclined part.  12) Contactor according to claim 11, characterized in that the electrically insulating washers (5) comprise a part of trapezoidal shape, and in that it is formed two grooves respectively against the two washers (5) and between the second washer ( 5) and the additional thickness (89), with bracing by the cups (5), for mounting two flexible wires (8) in said grooves.