ACOUSTIC WARNING DEVICE FOR A VEHICLE STEERING WHEEL

Abstract

An acoustic warning device for a motor vehicle, having: a base part, a mobile control part, an electrical command detection circuit with at least two switches, the switches are normally closed switches, and the two switches are connected in series, in that at least one of the switches has two contacts that are isolated from one another.

Claims

1-14. (canceled)

15. An acoustic warning device for a motor vehicle, comprising: a base part, a control part, which is movable with respect to the base part, between a rest position and a pressed position, an electrical command detection circuit with at least two switches, each switch being arranged to change status when the control part transitions from the rest position to the pressed position, wherein the switches are normally closed switches when the control part is in the rest position, wherein: the two switches are connected in series, at least one of the switches comprises two contacts that are isolated from one another and arranged on one of the base part-control part assembly, and a contact bridge arranged on the other one of the base part-control part assembly, the contact bridge being arranged to connect the two contacts when said at least one switch is closed.

16. The acoustic warning device according to claim 15, wherein the electrical detection circuit comprises three switches.

17. The acoustic warning device according to claim 15, wherein each switch comprises two contacts isolated from one another on one of the base part-control part assembly, and a contact bridge on the other one of the base part-control part assembly, the contact bridge being arranged to connect the two contacts when said at least one switch is closed.

18. The acoustic warning device according to claim 17, wherein each switch has a contact connected in series with a contact of an adjacent switch of the command detection circuit.

19. The acoustic warning device according to claim 18, wherein the command detection circuit comprises a branch consisting of circuit strands, with at least two adjacent circuit strands each comprising at one end one of the contacts of the same switch, the contacts isolated from one another being arranged opposite the contact bridge of said switch.

20. The acoustic warning device according to claim 19, wherein the branch comprises an insulating material forming a substrate supporting the contacts isolated from one another and arranged opposite the contact bridge of said switch.

21. The acoustic warning device according to claim 19, wherein the branch comprises at least one insulating shell partially overmolded around the contacts isolated from one another and arranged opposite the contact bridge of said switch.

22. The acoustic warning device according to claim 21, comprising at least one reference protuberance, and wherein the insulating shell comprises elastic retaining or interlocking means, arranged so as to be elastically attached to the reference protuberance.

23. The acoustic warning device according to claim 15, comprising at least one guide unit for the control part, the guide unit comprising at least one mechanical stop in order to define the rest position, and wherein: one of the assembly of two isolated contacts-contact bridge is embedded on the control part, the other one of the assembly of two isolated contacts-contact bridge is integrally formed with the mechanical stop.

24. The acoustic warning device according to claim 23, comprising as many guide units as switches, and wherein, for each switch: one of the assembly of two isolated contacts-contact bridge is embedded on the control part, the other one of the assembly of two isolated contacts-contact bridge is integrally formed with the mechanical stop of a guide unit.

25. The acoustic warning device according to claim 23, wherein the other one of the assembly of two isolated contacts-contact bridge integrally formed with the mechanical stop is electrically isolated from the guide unit.

26. A vehicle steering wheel comprising an acoustic warning device according to claim 15.

27. The vehicle steering wheel according to claim 26, comprising a safety module attached to the control part.

28. A motor vehicle comprising a vehicle steering wheel according to claim 26.

Description

[0036] Other characteristics and advantages of the present invention will become more apparent upon reading the detailed description of several embodiments of the invention, which are provided by way of example but in no manner limited thereto, and illustrated by the attached drawings, in which:

[0037] FIG. 1 depicts a perspective view of part of an acoustic warning device, or part of a control device for an acoustic warning device, embedded on a vehicle steering wheel;

[0038] FIG. 2 depicts a connection hoop forming part of the acoustic warning device of FIG. 1,

[0039] FIG. 3 depicts the connection hoop of FIG. 2, to show an interaction with components of FIG. 1;

[0040] FIG. 4 depicts a cross-section of the acoustic warning device of FIG. 1;

[0041] FIG. 5 depicts a perspective view of an alternative of part of an acoustic warning device, embedded on a vehicle steering wheel;

[0042] FIG. 6 depicts a connection hoop forming part of the alternative acoustic warning device of FIG. 5,

[0043] FIG. 7 depicts a cross-section of the acoustic warning device of FIG. 5;

[0044] FIG. 8 depicts an alternative implementation of the connection hoop of FIG. 2.

[0045] FIG. 1 depicts a perspective view of part of an acoustic warning device comprising three switches 10 formed at three guide units of a movable control part 25 embedded on a vehicle steering wheel comprising notably a frame consisting of a hub (forming a base part 33), branches 32 and a rim 31.

[0046] The control part 25 is a plate which typically receives a safety module (an airbag), and which is movably mounted on the hub of the steering wheel frame. In a conventional manner, the control part 25 is movable between a rest position (FIG. 1) and a pressed position; when the driver wants to activate the acoustic warning device.

[0047] In order to detect this control movement, the acoustic warning device comprises three switches 10 which are normally closed (when the control part 25 is in the rest position), and which open during the transition to the pressed position. Thus, the detection is rapid (the status change of the switches 10 occurs as soon as the control part 25 leaves the rest position).

[0048] In order to limit the manual connection operations, provision is made to connect the three switches 10 in series, which allows for the provision of only two connection terminals 16 for connecting the switches 10 to the rest of the vehicle's on-board circuit.

[0049] Specifically, as depicted in FIGS. 2 and 3, each switch 10 comprises two contacts 11, isolated from one another. Furthermore, provision is made for a contact bridge 12 (which can be seen in FIG. 3 and especially in FIG. 4) arranged to connect the two contacts 11 together, when the switch 10 is closed. As a result, it is possible to provide a connection hoop 15 which is detailed in FIGS. 2 and 3, which connects the contacts 11 of two switches 10 in pairs, and which comprises the only two connection terminals 16 to be connected manually during assembly of the vehicle steering wheel. The dotted line of FIG. 3 shows the silhouette of the contact bridge 12 of each switch 10, and the electrical contact zones are shown as hatched, when the switches 10 are closed (the control part 25 is therefore in the rest position).

[0050] The connection hoop 15 therefore comprises the contacts 11 of each switch 10, and provision is also made for a collar 13 at the contacts 11 and clearly visible in FIG. 4 (which depicts a cross-section of a guide unit for the control part 25), which flexibly fits onto the head 21T of a guide screw 21 which is screwed into the hub of the frame. Thus, it is easy to mount the connection hoop 15 on the steering wheel.

[0051] It is further noted that the connection hoop is fixedly mounted on the hub; it therefore does not move during the acoustic warning commands, and it is less exposed to vibrations, which limits the mechanical/vibratory stress and the risk of noise. The service life is improved. Consequently, only the contact bridges 12 are movable in this implementation, and no electrical cable is therefore movable, which typically improves reliability (reduced risk of noise, friction, spurious movement, etc.).

[0052] In addition, FIG. 4 shows the construction details of the guide units for the control part 25 which is movable. Around the shoulder guide screw 21, provision is made for a return spring 23, a slider 22, and a damper 24 for guiding the control part 25.

[0053] Returning to FIG. 1, it can be noted that three guide units are provided, each with a switch 10, which guarantees that the movement of the control part 25 will be immediately detected, regardless of the position at which the driver presses, because the switches 10 are normally closed and all connected in series: as soon as one of the switches 10 opens, the entire circuit is open. Furthermore, there are only two connection terminals 16 to be connected manually during assembly of the depicted steering wheel.

[0054] FIG. 8 shows an alternative embodiment of the hoop 15 of FIG. 2. In fact, the hoop 215 of FIG. 8 can completely replace the hoop 15 of FIG. 2 in the assembly of FIG. 1 or 4. The difference to be noted relates to the shells which overmold the contacts of each switch.

[0055] In fact, each shell is C-shaped (as in FIG. 2), but in FIG. 8, the openings of each C are all oriented in a single assembly direction Dm. Simplified assembly is thus possible. The hoop 215 can be attached to the shoulder screws according to a single movement in the assembly direction Dm.

[0056] Provision can also be made to fit all the shoulder guide screws 21 and the control part 25 on the base part 33 in order to then attach the hoop 215 and connect it via the connection terminals 216. In the example depicted, the assembly direction Dm is contained in a plane perpendicular to the shoulder guide screws 21, but other orientations and assembly directions may be provided.

[0057] It should be noted that the contacts 11 of the hoop 215 are not visible in FIG. 8, as they are arranged at the lower surface of the insulating shells or overmoldings, which is hidden in this FIG. 8.

[0058] FIGS. 5, 6 and 7 depict an alternative embodiment. A control part 125 is movably mounted on three guide units, each of which bear a switch 110.

[0059] As shown in FIG. 7, each guide unit herein consists of a guide screw 121, which forms a slide rail for the control part 125, and a spring 123 is fitted between the hub (the base part 133) and the control part 125 in order to push it back into the rest position (upward, as depicted in FIG. 7).

[0060] Furthermore, each switch 110 comprises a fixed contact 111 integral with a head 121T of a guide screw 121 and a mobile contact 112 integral with the control part 125. A connection hoop 115 shown in FIG. 6 connects the fixed contacts 111 in series, which allows for the provision of just one single connection terminal 116 for the three fixed contacts 111. Moreover, in FIGS. 4 and 7, it is possible to see that each mobile contact has a connection terminal 116. In total in this embodiment, four connection terminals 116 must be connected manually (instead of six if each switch were to have two connection terminals, as known in the background art).

[0061] It will be understood that various modifications and/or improvements which are obvious for the person skilled in the art may be made to the different embodiments of the invention described in this present description without departing from the scope of the invention.