Steering wheel with an airbag module

Abstract

Steering wheel (5) with an airbag module (10) which has: - a housing element (30) with a housing section (31), - an inflator (95) attached to the housing section (31), - a cover (20) which is attached to the housing section (31), - an airbag cushion (90) housed in a receiving unit defined by the housing section (31) and the cover (20), wherein the housing element (30) comprises a first fastening device (40), a second fastening device (40) and an elastically flexible, U-shaped first positioning device (42) extending from the housing section (31) of the housing element (30), wherein the first positioning device (42) comprises two lateral legs (46) and a cross piece (44) connecting the two lateral legs (46) and each of the lateral legs (46) of the first positioning device (42) has a first thickness in its module-side end section and a second thickness in its cross-piece-side end section, wherein the first thickness is smaller than the second thickness, and - a steering wheel body with a hub area for receiving at least one section of the airbag module (10), wherein the steering wheel body has a third fastening device that interacts with the first fastening device (40), a fourth fastening device that interacts with the second fastening device (40), and a second positioning device (76) with a lower contact surface (76a) that interacts with the transverse part (44) of the first positioning device (42), characterized in that each of the lateral legs (46) of the first positioning device (42) has a first width at the location of the first thickness and a second width at the location of the second thickness, wherein the second width is smaller than the first width.

Description

[0001] The invention relates to a steering wheel of a vehicle according to the preamble of claim 1 and an airbag module configured to be part of such a steering wheel according to the preamble of claim 14.

[0002] Such a steering wheel comprises a steering wheel body and an airbag module attached to this steering wheel body, in particular in such a way that the airbag module can be pressed downwards towards the steering wheel body to activate the vehicle's horn (so-called "floating module concept").

[0003] Such a steering wheel is known, for example, from CN 2 12 604 810 U. The airbag module of this steering wheel comprises a housing element with a housing section, an inflator attached to the housing section of the housing element, a cover attached to the housing section by means of snap-fit ​​devices, and an airbag cushion housed in a receiving unit defined by the housing section and the cover. The housing element has a first fastening device, a second fastening device, and an elastically flexible, U-shaped first positioning device. The fastening devices and the positioning device all extend from the housing section and are parts of the housing element. The first positioning device has two lateral legs and a cross member connecting the two lateral legs.The steering wheel body has a hub area for receiving the airbag module and includes a third mounting device that interacts with the first mounting device, a fourth mounting device that interacts with the second mounting device, and a second positioning device that has a lower contact surface that interacts with the transverse part of the first positioning device. This means that, in the state where the airbag module is not depressed, the transverse part of the first positioning device and the lower contact surface of the second positioning device are in contact, thus defining the axial position of the first positioning device relative to the second positioning device.During the assembly process of the airbag module on the steering wheel body, the lateral legs of the first positioning device are elastically bent away by the second positioning device and return to their undistorted initial state after completion of the assembly process.

[0004] The generic patent US 2015 / 0069739A1 also shows such a steering wheel, with the cross-section of each U-shaped first positioning device having a greater thickness than the lateral legs.

[0005] A similar design is also known from US 2020 / 0 017 057 A1, in which, however, the elastic U-shaped positioning element is arranged on a mounting plate and also has a damping function.

[0006] Based on this state of the art, it is an object of the invention to improve the steering wheel and in particular its airbag module in such a way that the airbag module can be more easily mounted on the steering wheel body.

[0007] This problem is solved by a steering wheel having the features of claim 1. An airbag module suitable for being part of such a steering wheel is defined in claim 14.

[0008] During the installation of the airbag module on the steering wheel housing, the first positioning element, namely its lateral legs, is elastically deflected because the transverse piece is pushed away by the second positioning element when the airbag module is inserted. This movement generally occurs in a radial direction. Due to leverage, the elastic deformation of the lateral legs of the first positioning element occurs primarily at their module-side end. According to the invention, the thickness of each of the lateral legs of the first positioning element is reduced in its module-side end region. This measure enhances the effect of the lateral legs being deformed primarily at their housing-side end, so that the module-side end sections of the lateral legs act almost like a hinge in the radial direction.

[0009] It is often desirable (or necessary) to dimension the first positioning device to withstand the forces that occur when the airbag module is ignited and the airbag deploys. Particularly at the end of the airbag deployment, high tensile forces act on the lateral legs. To compensate for the reduced thickness, the invention therefore provides that each lateral leg has a first width at its module-side end section and a second width at its cross-piece-side end section, the second width being smaller than the first width. "Width" refers to the extent in a circumferential direction (essentially perpendicular to a radial direction), and "thickness" refers to the extent in a radial direction.

[0010] Since the tensile strength (the factor that determines the tensile force that each lateral leg can withstand) depends essentially on the cross-sectional area, it is preferred that each of the lateral legs of the first positioning device has a substantially constant cross-sectional area along its entire length (in the axial direction) of the lateral legs, so that no “weak point” is created.

[0011] In a preferred embodiment, the first positioning device is made of plastic, which allows for simpler and more cost-effective handling of the thickness development. In this case, it is often further preferred that the first positioning device is integral with the housing section (the housing element, to which the housing section and the first positioning device belong, is often a single plastic part).

[0012] In a preferred embodiment, the cover is snapped to a housing section of the housing element by means of locking devices. To prevent the cover from detaching from the housing section during airbag deployment, a locking plate can be provided that locks the locking devices to the housing element. This locking plate prevents any movement of the cover's locking devices once the airbag module is fully assembled. The locking plate typically extends along the outer surface of a housing base and is attached to it after the cover has been snapped onto the housing section. Sections of the locking plate's edge extend to the cover's locking devices, preventing them from moving radially inward to a degree that would allow detachment from the housing section.

[0013] In a further preferred embodiment, the airbag module also includes a limiting device located near the first positioning device. This limiting device is arranged to restrict the deflection of the first positioning device in order to prevent breakage of the first positioning device during disassembly. This limiting device allows movement of the first positioning device (which is necessary during both assembly and disassembly), but limits this deflection to prevent breakage due to excessive deflection. This limiting device preferably extends parallel to the lateral legs of the first positioning device.The advantage of such a limiting device is as follows: When the airbag module is mounted to the steering wheel housing, the U-shaped first positioning device is "automatically" deflected by the second positioning device of the steering wheel housing, so there is no risk of excessive deflection. However, during disassembly, the first positioning device often has to be manually deflected (i.e., bent), creating the risk of it being bent too far and breaking. In this case, the entire airbag module usually has to be disposed of. A limiting device reliably prevents this.

[0014] Such a limiting device is particularly useful because, due to the reduced thickness of the lateral legs at their module-side end, the first positioning device can easily be bent radially (as desired), which could lead to an undesired breakage during disassembly if no limiting device is provided.

[0015] The limiting device can be designed as at least one projection on the locking plate. This makes it particularly easy to give the limiting device the necessary stability, since the locking plate is often made of sheet metal. Because the locking plate is usually a stamped and bent part, an additional manufacturing step can be omitted (the limiting device is formed by the bending process that is necessary anyway).

[0016] Alternatively, the limiting device can also take the form of at least one projection on the housing element. In this case, the locking plate often has a recess or opening at the location of the limiting device.

[0017] The invention will now be described in more detail with reference to preferred embodiments and the figures. The figures show: Fig. 1: all relevant elements of a first embodiment of a steering wheel according to the invention in a highly schematic cross-sectional representation, Fig. 2: a sub-assembly of an airbag module, consisting of in Fig. The elements shown in section 1 are formed. Fig. 3: the complete airbag module in a representation according to Fig. 2, Fig. 4: all in Fig. 1. Elements shown in fully assembled state, Fig. 5: the cover made of Fig. 1 in a view from below from the direction of R1 in Fig. 1, Fig. 6: the in Fig. 1 Housing element shown in a view from below from direction R2 in Fig. 1, Fig. 7: the in Fig. 1 Locking plate shown in a view from below from the direction R3 in Fig. 1, Fig. 8: the in Fig. 1 Fitting shown in a top view from direction R4 in Fig. 1, Fig. 9a: the first and third positioning device of the in Fig. 1 of the housing shown in a side view from the direction of R5 in Fig. 1, Fig. 9b: the in Fig. 9a shows the first positioning device in a side view from the direction of R7. Fig. 9a, Fig. 10a: a variation of a first positioning device in a representation according to Fig. 9a, Fig. 10b: the in Fig. 9a first positioning device shown in a representation according to Fig. 9b, Fig. 11: a hook of the housing element made of Fig. 1 in a side view from the direction of R6 in Fig. 1, Fig. 12: A complete steering wheel according to a second embodiment of the invention in a perspective detail view, Fig. 13: the steering wheel off Fig. 12 in a top view, Fig. 14: a cross-sectional view along the plane AA in Fig. 13, Fig. 15: the locking plate of the second embodiment in a perspective view, Fig. 16: a third embodiment of the invention in a representation according to Fig. 4, Fig. 17: a detail of the embodiment of the Fig. 16, however in a more detailed and perspective view, Fig. 18: a first positioning device in a further embodiment, and Fig. 19: a first positioning device in a further embodiment.

[0018] With regard to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. Section 10 describes a first embodiment of the invention. The illustrations are highly schematic, so that the relevant features are clearly recognizable.

[0019] Fig. Figure 1 shows elements of an airbag module as well as part of a steering wheel body, namely a fitting. Of course (and as will be seen later), the complete steering wheel body comprises further elements such as a rim, spokes, and the like, but these elements are not relevant to the invention, so they are shown in the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. 10 of the first embodiment are not shown. Furthermore, in Fig. 1. Coil springs are shown, which act between the airbag module and the fitting 17. Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. 10 show details of the in Fig. 1 element shown.

[0020] The airbag module includes a cover 20 ( Fig. 1 and Fig. 5), a housing element 30 ( Fig. 1 and Fig. 6), a locking plate 50 ( Fig. 1 and Fig. 7), an airbag cushion 90 and an inflator 95. First, the elements of the airbag module are described: As already mentioned, in the Fig. 1 and Fig. Figure 5 shows the cover 20 of the airbag module. This cover 20 is usually made of a plastic material and has a cover side wall 24 and a roof 22. As is generally known for airbag modules, locking devices 26 in the form of locking hooks 26 extend from the lower edge of the cover side wall 24.

[0021] As also mentioned previously, in the Fig. 1 and Fig. Figure 6 shows the housing element 30. This housing element 30 is typically a one-piece plastic part and comprises a housing section 31. This housing section 31 and the cover 20 form (in the assembled state) a receptacle for the airbag cushion 90. The housing section 31 comprises a housing base 32 and a housing side wall 34. The housing base 32 has at least one hole 36 for receiving the locking device 26 of the cover, so that the cover 20 can be locked onto the housing section 31.

[0022] The housing base 32 further features a hole 37 for the inflator 95, projections 39 for the coil springs 60, and holes 38 for attaching the locking plate 50. The housing base 32 may also feature fastening means for horn contacts, which, however, are located in the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. 10 are not shown.

[0023] In order to attach the housing element 30 (and thus the entire airbag module) to the steering wheel body (in the embodiment shown, to the steering wheel assembly 17), the housing element 30 of the first embodiment also has the following features: Two hooks 40a, 40b extend from the base of the housing 32, serving as first and second fastening devices (see Fig. 1, Fig. 6 and Fig. 10). These hooks 40 are relatively stable and can withstand the forces that may occur when the airbag cushion 90 is inflated by the inflator 95.

[0024] Furthermore, a U-shaped first positioning device 42 extends from the housing section 31 to ensure correct positioning of the airbag module 10, particularly along the mounting axis of the airbag module on the steering wheel body. This first positioning device 32 comprises two lateral legs 46 and a transverse piece 44 that connects these lateral legs 46 (see Fig. 1, Fig. 6, Fig. 9a and Fig. 9b). This first positioning device extends substantially from an edge of the housing base and is located on a center line; the two hooks 40a, 40b are usually arranged symmetrically to this center line C.

[0025] As in the Fig. 9a and Fig. As can be clearly seen in 9b, the width (in the circumferential direction) of the lateral legs 46 decreases from their module-side end to the module-remote end ( Fig. 9a), while their thickness (in the radial direction) increases ( Fig. 9b). The increase in thickness and the decrease in width are preferably achieved such that the cross-sectional area remains substantially constant. In the illustrated embodiment, the lateral legs have a first section (module-side section) 46a with a first width and thickness, an intermediate section 46b in which the width decreases and the thickness increases, and a second section (cross-piece-side section) 46c with a second width and thickness. This increases flexibility in the radial direction without reducing tensile strength and thus reduces the force required to engage the airbag module 10 with the steering wheel assembly 70 without reducing the force it can withstand when the airbag module is deployed. Due to the presence of the limiting device, the increased flexibility does not increase the risk of breakage.

[0026] The shaping of the lateral legs with three different sections, as just shown, is often preferred to define a “hinge area” in the first section 46a, but is not absolutely necessary.

[0027] Furthermore, it should be noted that the point of least thickness need not be located directly at the module-side end of the lateral legs 46; it is sufficient if it is located in the module-side end region, preferably at or near the connection point with the housing section 31. For example, it is possible that the lateral legs have a "waist" in the module-side end region. A variant of the embodiment of Fig. 9a and Fig. 9b with such a waist is in the Fig. 10a and Fig. 10b shown.

[0028] In the illustrated embodiment, the housing element 30 further comprises two posts 48, which are arranged between the lateral legs 46 of the first positioning device 42; these posts 48 form a third positioning device. The posts 48 extend parallel to each other at a distance D1 ( Fig. 9) The posts (like the rest of the housing) are made of plastic and, because they have free ends, can be deformed to some extent, especially in the areas indicated by the arrows in Fig. 9 indicated directions.

[0029] To secure the cover 20 after it has been snapped onto the housing section 31, a locking plate 50 is provided (see Fig. 1 and Fig. 7) This locking plate 50 is preferably a one-piece sheet metal part. This locking plate 50 has a hole 54 for the inflator, mounting holes 56 for fastening (e.g., screwing or riveting) the locking plate 50 to the housing base 32, and holes 58 for the projections 39. Furthermore, this locking plate 50 has a recess 53 and a projection 52 at the location of the U-shaped first positioning device 42 of the housing element 30. The projection 52 is formed by an angled section and acts as a limiting device next to the recess 53.

[0030] The steering wheel controls 17 (see Fig. 1 and Fig. 8) has a hole 72 for each hook 40a, 40b, and a retaining spring 74 is held on the underside of the steering wheel assembly so that the hooks 40a, 40b can be snapped onto this retaining spring 74, as is known from the prior art. A common retaining spring 74 or a separate retaining spring for each hook 40a, 40b may be provided. According to the definition chosen in this application, the retaining spring forms part of the third and fourth fastening devices, which interact with the first and second fastening devices (the hooks 40a, 40b), and the retaining spring is part of the steering wheel body. Thus, the first to fourth fastening devices contribute to fastening the airbag module 10 to the steering wheel body. On the steering wheel assembly 70, projections 78 for positioning the coil springs are provided, similar to those on the base of the housing.

[0031] Furthermore, a second positioning device 76 in the form of a hook is provided for the first positioning device 42 of the housing element 30. This positioning device 76 comprises a lower contact surface 76a for contacting the transverse piece 44 of the first positioning device, thus generating axial positioning (Z-positioning / positioning along the mounting axis of the airbag module 10 or positioning along a steering column axis). The second positioning device 76 also has side surfaces 76b, 76c, which are spaced apart by a distance D2. This distance D2 is equivalent to or nearly equivalent to the distance D1 between the two posts of the third positioning device.

[0032] Fig. Figure 2 shows a subassembly of the airbag module 10. This subassembly consists of the cover 20, the housing element 30, the airbag cushion 90, and the inflator 95. It can be seen that the cover 20 is snapped onto the housing element 30 (namely the housing base 32) by means of the locking hooks 26 extending through the holes 36.

[0033] In a subsequent assembly step, the locking plate 50 is attached to the housing base 32, e.g., via bolts provided on the inflator 95. The result of this assembly step is shown in Fig. Figure 3 shows the complete airbag module 10. It can be seen that the locking plate 50 extends to the inner edges of the locking hooks 26, so that these cannot come loose even when high pressure forces are exerted on the cover during the deployment of the airbag cushion 19. Fig. Figure 3 also shows that the projection 52 (the limiting device) is located near the U-shaped first positioning device 42, but has a certain distance from this positioning device 42, so that the positioning device can bend inwards (see arrow in Fig. 3), but only to a certain extent.

[0034] Fig. Figure 4 shows the airbag module mounted (i.e., snapped into place) on the steering wheel instrument panel 70. Fig. 3. In this assembly step, the retaining spring 74 and the U-shaped first positioning device 42, namely its lateral legs 46, are elastically deformed. The distance between the U-shaped first positioning device 42 and the projection (limiting device) 52 of the locking plate allows sufficient deflection of the U-shaped first positioning device 42 for this assembly step, but prevents the U-shaped first positioning device 42 from being bent more than necessary for this assembly step.

[0035] In the fully assembled state, the coil springs are pre-tensioned, pressing the cross piece 44 of the U-shaped first positioning device against the lower contact surface 76a of the second positioning device 76, thus generating axial positioning. Furthermore, the second positioning device 76 is positioned between the posts 48 of the third positioning device, thus generating circumferential positioning.

[0036] The Fig. 12, Fig. 13, Fig. 14 to Fig. Figure 15 shows a second embodiment, similar to the first embodiment but in more detailed illustrations. The difference is that the airbag module 10 of the second embodiment does not have a third positioning device between the lateral legs of the first positioning device, so that the second positioning device 76 of the steering wheel body interacts only with the first positioning device of the airbag module and does not contribute to positioning in the circumferential direction. Apart from this, the description of the first embodiment can be directly applied to the second embodiment, and identical elements are designated by the same reference numerals.

[0037] The Fig. 16 and Fig. Figure 17 shows an embodiment that is also similar to the first embodiment. The difference here is that the limiting device is not part of the locking plate, but part of the housing element 30. In this embodiment, the limiting device is designed in the form of two projections 49 extending from the housing base 32 (see Figure 17). Fig. 16) extend through the indentation of the locking plate 50.

[0038] The Fig. 18 and Fig. Figure 19 shows alternative embodiments of the first positioning device 40. As above with regard to the Fig. 9a, Fig. 9b, Fig. 10a and Fig. As described in 10b, the width (in circumferential direction) of the lateral legs 46 decreases from their module-side end towards the module-remote end, while their thickness (in radial direction) increases, so that the cross-sectional area remains essentially constant. Reference symbol list 5 Steering wheel 10 Airbag module 20 Cover 22 Roof of the cover 24 Cover side panel 26 locking hooks (locking device) 30 Housing element 31 Housing section 32 Case base 34 Case side panel 36 holes for cover latches 37 holes for inflator 38 holes for attaching the locking plate 39 advantage for spiral spring 40a first hook (first fastening device) 40b second hook (second fastening device) 42 U-shaped first positioning device 44 Cross piece 46 lateral thigh 46a first section (module-side section) 46b Intermediate section 46c second section (cross-piece side section) 48 Third positioning device (post between the side legs) 49 Projection from the housing element / limiting device 50 locking plate 52 Projection (angled part / limiting device) 53 Indentation 54 holes for inflator 56 mounting holes 58 holes for a 39 lead 60 spiral springs 70 Steering wheel controls (part of the steering wheel body) 72 holes for hooks (part of the third and fourth fastening device) 74 Mounting spring (part of the third and fourth mounting device) 76 second positioning device 76a lower contact surface 76b, 76c side surface 78 advantage for spiral spring 80 spokes (part of the steering wheel body) 82 Rim (part of the steering wheel body) 90 airbag cushions 95 Inflator C Center line

Claims

[1] Steering wheel (5) with an airbag module (10) which has: - a housing element (30) with a housing section (31), - an inflator (95) attached to the housing section (31), - a cover (20) which is attached to the housing section (31), - an airbag cushion (90) housed in a receiving unit defined by the housing section (31) and the cover (20), wherein the housing element (30) comprises a first fastening device (40), a second fastening device (40) and an elastically flexible, U-shaped first positioning device (42) extending from the housing section (31) of the housing element (30), wherein the first positioning device (42) comprises two lateral legs (46) and a cross piece (44) connecting the two lateral legs (46) and each of the lateral legs (46) of the first positioning device (42) has a first thickness in its module-side end section and a second thickness in its cross-piece-side end section, wherein the first thickness is smaller than the second thickness, and - a steering wheel body with a hub area for receiving at least one section of the airbag module (10), wherein the steering wheel body has a third fastening device that interacts with the first fastening device (40), a fourth fastening device that interacts with the second fastening device (40), and a second positioning device (76) with a lower contact surface (76a) that interacts with the transverse part (44) of the first positioning device (42), characterized by , that each of the lateral legs (46) of the first positioning device (42) has a first width at the location of the first thickness and a second width at the location of the second thickness, the second width being smaller than the first width. [2] Steering wheel according to claim 1 or claim 2, characterized by, that the module-side end section with the first thickness is located at the connection with the housing section (31) and the cross-piece-side end section with the second thickness is located at the level of the cross piece (44). [3] Steering wheel according to claim 1 or claim 2, characterized by , that each of the lateral legs (46) of the first positioning device (42) has a first cross-sectional area at its module-side end and a second cross-sectional area at its cross-piece-side end, wherein the first cross-sectional area and the second cross-sectional area are substantially the same. [4] Steering wheel arrangement according to one of the preceding claims, characterized by , that the cover (20) is attached to the housing section (31) via locking devices (26) and that the airbag module (10) further comprises a locking plate (50) for locking the locking devices (26). [5] Steering wheel unit according to any one of the preceding claims, characterized by, that the airbag module further comprises a limiting device near the first positioning device (42), wherein the limiting device is arranged such that it limits the deflection of the first positioning device (42). [6] Steering wheel unit according to claim 5, characterized by , that the limiting device is designed in the form of at least one projection (49, 52) which extends substantially parallel to the lateral legs (46) of the U-shaped positioning device (42). [7] Steering wheel unit according to claim 6, characterized by , that the at least one projection (49) is part of the housing element (30), wherein the at least one projection (49) preferably extends from a housing base (32) accommodating the inflator (95). [8] Steering wheel unit according to claims 4 and 5, characterized by , that the at least one projection (52) is part of the locking plate (50). [9] Steering wheel according to any one of the preceding claims, characterized by , that a third positioning device extends between the lateral legs (46) of the first positioning device (42), which cooperates with the second positioning device (76). [10] Steering wheel according to claim 9, characterized by , that the third positioning device is formed in the form of two posts (48) and that the second positioning device (76) extends between the two posts (48). [11] Steering wheel according to any one of the preceding claims, characterized by , that the first fastening device is a first hook (40a) and the second fastening device is a second hook (40b), wherein the first hook (40a) and the second hook (40b) are preferably rigid. [12] Steering wheel unit according to claim 9, characterized by, that the first hook (40a) is in the 3 o'clock position, the second hook (40b) is in the 9 o'clock position and the first positioning device (42) is in the 12 o'clock position. [13] Steering wheel according to any of the preceding claims, characterized by , that at least one pre-tensioned spring (60) is provided between the airbag module (10) and the steering wheel body in such a way that the airbag module (10) can be pressed downwards towards the steering wheel body. [14] Airbag module (10) configured to be part of a steering wheel according to any one of claims 1 to 11 and comprising: - a housing element (30) with a housing section (31), - an inflator (95) attached to the housing section (31), - a cover (20) attached to the housing section (31), and - an airbag cushion (90) housed in a receiving unit defined by the housing section (31) and the cover (20), wherein the housing element (30) comprises a first fastening device (40), a second fastening device (40) and an elastically flexible, U-shaped first positioning device (42) extending from the housing section (31) of the housing element (30), wherein the first positioning device (42) has two lateral legs (46) and a cross piece (44) connecting the two lateral legs, and each of the lateral legs (46) of the first positioning device (42) has a first thickness in its module-side end section and a second thickness in its cross-piece-side end section, wherein the first thickness is smaller than the second thickness, characterized by , that each of the lateral legs (46) of the first positioning device (42) has a first width at the location of the first thickness and a second width at the location of the second thickness, the second width being smaller than the first width.

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