INTEGRATED STEERING WHEEL, VIBRATION DAMPER AND DRIVER AIRBAG

Abstract

A component assembly comprising: a steering wheel (18) with a plurality of support elements (330); a plurality of damper spring elements or bushings (22), wherein each damper spring element or bushing (22) is held in a corresponding plurality of support elements (330); a motor vehicle component (14) that is attached to the steering wheel (18) and positioned on the plurality of damper spring elements or bushings (22); a plurality of mounting elements (34a-c) extending from the motor vehicle component (14) to attach the motor vehicle component (14) to the steering wheel (18), each mounting element (34a-c) extending through the plurality of support elements (330) and attached to the steering wheel (18); a fastening mechanism retaining wire (20) attached to the plurality of support elements (330), wherein the plurality of mounting elements (34a-c) are attached to the fastening mechanism retaining wire (20) to fasten the motor vehicle component (14) to the steering wheel (18); and a horn switch (16) which is located on the plurality of damper spring elements or grommets (22) and is held between the plurality of damper spring elements or grommets (22) and the motor vehicle component (14).

Description

[0001] The present invention relates to motor vehicle systems and in particular to a method and a device for damping a steering wheel assembly.

[0002] Motor vehicles are typically equipped with steering wheel assemblies containing airbag modules designed to protect occupants during a collision. These airbag modules are usually mounted within the steering wheel, which is in turn attached to a shaft connected to the wheels at the front of the vehicle. Engine vibrations are also transmitted through the vehicle frame to the steering wheel via its mounting point on the wheel. This exposes the steering wheel to vibrations generated by the vehicle's operation. To enhance driver comfort and minimize vibrations transmitted through contact with the steering wheel, a damping system is often required within the steering wheel assembly.One challenge is optimizing the installation space for the damping system, as the airbag module occupies a large portion of the available space within the steering wheel assembly. Another challenge is reducing the weight of the damping system. Therefore, it is desirable to provide an improved method and device for damping the vibrations transmitted through the steering wheel.

[0003] Exemplary steering wheel assemblies, each comprising a steering wheel with a motor vehicle component attached to it and positioned on damping elements, are shown in WO 2019 / 183 167 A1, US 2017 / 0 144 594 A1, DE 10 2014 000 587 A1 and US 6 793 237 B2.

[0004] The present invention provides a steering wheel assembly for a vehicle and is primarily directed to a damping system that interacts with the steering wheel's housing. The assembly comprises a damping system contained within the housing that enables a suspended state of a motor vehicle component, such as a driver airbag module or assembly, with respect to both vertical and lateral movements. This reduces the vibrations normally felt by the driver due to the designed movement of the airbag module within the steering wheel assembly. The assembly may also include a horn switch coupled to the steering wheel and the airbag module. The horn switch generates an electrical signal based on driver input to activate the vehicle's horn.Overall, the damping system is functionally connected to the fitting to dampen the vibrations or frequencies that would otherwise be transmitted to the steering wheel assembly when the vehicle is in operation.

[0005] Further applications of the present invention will become apparent from the following detailed description. It is understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, serve only for illustration and are not intended to limit the scope of the invention.

[0006] The invention is described by means of examples and with reference to the accompanying drawings, in which: Fig. 1 is an exploded view of the steering wheel assembly according to the present invention; Fig.2 a perspective view of the hub plate of a fitting of the steering wheel assembly, which contains a retaining wire; Fig. 3 a perspective view of the hub plate of a steering wheel assembly Fig. 2, which contains damper spring elements or damper springs according to the present invention; Fig. 4 a cross-sectional view of the steering wheel assembly and the damper spring element of Fig. 3 is; Fig. 5 a perspective view of the hub plate of a steering wheel assembly Fig. 3, which further includes damper spring isolators; Fig. 6 A cross-sectional view of the steering wheel assembly, the damper spring element and the damper spring isolator of Fig. 5 is; Fig. 7 a perspective view of the hub plate of a steering wheel assembly Fig. 5, which also contains a horn switch; Fig.8 A cross-sectional view of the steering wheel assembly, the damper spring element, the damper spring isolator and the horn switch of Fig. 7 is, Fig. 9 a perspective view of the hub plate of a steering wheel assembly Fig. 7, which also contains a driver airbag module; Fig. 10 a cross-sectional view of the hub plate of a steering wheel assembly, a damper spring element, a damper spring isolator, a horn switch and an airbag module made of Fig. 9 is; Fig. Figure 11 shows a schematic representation of the steering wheel assembly and the driver airbag module as a spring mass.

[0007] The following description of various embodiments is merely exemplary and is in no way intended to limit the invention, its application, or uses. Although the following description generally refers to a device for damping vibrations typically transmitted through the steering wheel, it is understood that this device could be modified in a number of ways and still be used within a steering wheel assembly. It is therefore understood that the following explanations are not intended to limit the scope of the appended claims.

[0008] In the Fig.Figures 1 to 11 depict a steering wheel assembly 10 for use in a motor vehicle. It is noted that a related and exemplary steering wheel assembly is described in US Patent No. 7,533,897 B1, the teachings of which are incorporated herein by reference in their entirety. The manufacture of steering wheel assemblies is known in the art, and therefore it is assumed that various details and subtleties of how the components are connected, apart from the inventive aspects of the present embodiments, are well known to those with ordinary technical knowledge.

[0009] The steering wheel assembly 10 can comprise a vehicle component or an airbag module 14, a horn switch 16, and a steering wheel 18. The steering wheel 18 comprises a metal fitting 300 with spokes 303, a rim 304, and a hub connection 305, which connects the fitting 300 to a steering shaft (not shown). The steering wheel assembly 300, which is covered with a foam and / or resin 322 molded around the rim 304 of the steering wheel assembly 300, an overmolded foam or separately molded back cover, which is often connected to the steering wheel assembly, a leather cover and switches often comprise the complete steering wheel 18. In the illustrated embodiment, the horn switch 16 is arranged between the airbag module 14 and the steering wheel 18, and the airbag module 14 is attached to the steering wheel assembly 300 by a fastening mechanism 20, which is also referred to as the driver airbag module retaining wire or retaining element 20.As can be seen, the horn switch 16 can be arranged between any two interacting elements configured to compress the elements of the horn switch 16. As shown in the following figures and further explained below, an upper horn spring housing 50 and a lower horn spring housing 52 are two such interacting elements. As in . Fig. Figure 1 shows damper spring elements or grommets 22 and damper spring insulators or spacers 21 between the horn switch 16 and the retaining element 20.

[0010] As in Fig. 1 and Fig.As shown in Figure 9, an exemplary airbag module 14 comprises a cover 28, which serves to protect an airbag and an associated inflation device. The cover 28 is shown approximately triangular; however, any desired shape, such as a rectangular shape, can be used. In general, the cover 28 is made of a polymeric material, such as polyester (TPE), but any other suitable material can also be used. The cover 28 can be connected to a mounting plate 21 in a known manner to define a cavity for receiving the airbag and an inflation device. The inflation device is capable of triggering the airbag upon detection of an impact event.

[0011] The plate 21, located on a lower part of the airbag module 14, can include a central opening for receiving and supporting part of the inflation device, a first or upper side, and a second or lower side. The upper side is generally configured to form an interface between the airbag and the inflation device. As shown in Fig.As shown in Figure 1, the lower side of the plate 21 generally includes a plurality of prongs or pins 34a-c for attachment to the steering wheel 18 and a plurality of flanges for coupling the plate 21 to a counterpart on the cover 28. In this embodiment, the second or lower side of the plate 21 includes three pins 34a-c, each having at least one fastening mechanism, such as a conical tip, a clip, a hook, or a flange, which can each be actuated to couple the airbag module 14 and the horn switch 16 to the fitting 300, as will be described in more detail below. The pins 34a-c can be arranged at various locations, for example, at the corners of a virtual rectangle or trapezoid. The arrangement of three pins is necessary for the static stability of the DAN assembly 28.If desired, four or more such pins can be used, depending on the design of the steering wheel 18 and the airbag module 14.

[0012] The horn switch 16 can comprise a first switch housing 50 and a second switch housing 52. The first switch housing 50 comprises three annular support elements 60, each of which has an opening 76. The second switch housing 52 comprises three annular support elements 160 aligned coaxially with the annular support elements 60; each support element 160 comprises a complementary opening 176. Each set of aligned openings 76 and 176 accommodates one of the first, second, and third prongs or pins 34a-c and bushings that effectively increase the diameter of each pin (if used). The first horn switch housing 50 and the second horn switch housing 52 have an open design with a number of legs or side parts 50L, 52L that can be arranged on or around the central part of the plate.

[0013] The openings 76, 176 of the horn switch 16 can each receive one of the pins or prongs 34a-c to align and connect the first or upper housing 50 with the second housing 52. Furthermore, each support element 60 of the upper switch housing 50 has an annular groove 86, and each support element 160 of each second or lower switch housing 52 has a corresponding groove 186 for receiving a spring 54.

[0014] The horn spring 54 can be any suitable helical spring. The horn spring 54 has a suitable length and a spring constant such that it displaces the first switch housing 50 from the second switch housing 52, so that the openings 76 of the first switch housing are spaced apart from the openings 176 of the second housing and the exposed sections of the switch leads are moved into a disengaged position. Compressing one or more of the horn springs 54 causes the exposed section of a cable conductor of the first housing 50 to contact the exposed section of a cable conductor of the second switch housing 52, thereby closing the associated circuit in a known manner.

[0015] As in Fig. 1 and Fig.As can be seen in Figure 2, the steering wheel 18 comprises an armature 300, which is generally made of a material such as magnesium, aluminum, or steel. The armature 300 defines a plurality of raised and annular support elements 330, each hollow support element 330 having an opening 336 for receiving one of the first, second, and third pins or studs 34a-c, which extend from the airbag module mounting plate 21 to connect the airbag module 14 and the horn switch 16 (if used) to the armature 300 of the wheel. The top of each support element 330 has a flat surface that can act or function as an anvil or reaction surface and receives and / or supports each of the lower housing supports 160 of the lower horn switch housing 52. An inner annular surface 332 is defined as the inner wall of each support element 330. Fig.Figure 4 shows a rib 334 that extends circumferentially along a central section of each inner annular surface 332 and interacts with an outer circumferential groove 26 formed on each damper spring element or grommet 22 to retain the respective grommet 22 in the corresponding support element 330. The fitting 300 can further be configured to include a plurality of first posts, second posts, hooks, or other fastening features (not shown) that can be actuated to interact with or retain the fastening mechanism 20, as described below. The fitting 300 further includes a hub area 302 having a connector 305 for coupling the fitting 300 to a steering shaft (not shown) so that the driver can steer the vehicle in a known manner.

[0016] A first embodiment of a fastening mechanism 20 comprises a retaining wire (spring clip) 20 that is elastically attached to a lower section 301 of the fitting 300. The retaining wire 20 may consist of one or more components and is generally made of a suitable material that can be elastically deformed, including polymers, but typically of a metal such as aluminum or spring steel. The retaining wire 20 is generally formed in one piece and has a uniform thickness. The wire thickness is generally selected such that the retaining wire 20 can hold the pins 34a-c of the airbag module 14 by being positioned on a bearing surface formed on the fitting 300 and arranged in an engagement slot under each support element 330, as is known in the art.

[0017] At least three damper spring elements or sleeves 22 are provided, each damper spring being vertically arranged, held, and embedded in a corresponding support element 330 to dampen frequencies emanating from the steering shaft (not shown) into the steering wheel assembly 10. In one embodiment, the multiple damper spring elements or sleeves 22 are designed as annular structures, allowing one of the posts 34a-c to be inserted through each damper spring element or sleeve and through each corresponding support element 330, thereby enabling the attachment of the airbag module 14 to the fastening mechanism 20 when the posts 34a-c are clipped to the spring clip or retaining wire 20. It should be noted that the damper spring elements or sleeves 22 can be geometrically shaped to accommodate the fastening process of any given airbag module.

[0018] According to the present invention, the lateral stiffness of the damper spring elements or bushings 22 can be iteratively tuned to obtain a resonant frequency of the mass of the driver airbag module that approximates the resonant frequency typically found in the steering wheel assembly 10 as mounted on the vehicle. The geometry and material of the damper spring elements or bushings 22 can therefore contribute to the desired lateral stiffness. Fluorosilicone is an example of a polymeric material suitable as a bushing material. Other suitable materials with similar technical or material properties are also conceivable. EPDM rubber (ethylene propylene diene monomer rubber), a type of synthetic rubber, is an elastomer characterized by a wide range of applications. Fluorosilicone rubber is a durable elastomer that is stable over extreme temperatures and resistant to compression set.Unlike silicone, fluorosilicone contains trifluoropropyl groups, which increase its chemical resistance to nonpolar solvents, fuels, oils, acids, and alkaline chemicals. The unique properties of fluorosilicone make it a problem-solving material widely used in industry, aerospace, and automotive for static sealing and damping applications.

[0019] Accordingly, the lateral stiffness or lateral displacement of the damper spring elements or bushings 22 can be related to the mass of the driver airbag assembly, as in Fig.Figure 8 is shown. The forces acting on the airbag module or assembly with respect to the lateral displacement Y include: (1) the lateral force Fa, which corresponds to the vibration force in the fitting 300; and (2) the lateral force Fb = KBY, where Fb = the stiffness force of the damper spring elements or bushings 22, KB = the stiffness of the damper spring, and Y = the lateral displacement. The forces acting on the airbag module or assembly with respect to the vertical displacement include: (1) F = mg, where m = mass of the driver airbag assembly and g = gravitational constant; and (2) Fk = KSX, where Fk = horn spring stiffness force, KS = horn spring stiffness, and X = vertical displacement. It becomes clear that the force attributable to gravity, i.e. F=mg, should be less than or equal to the horn spring stiffness force, Fk=KSX.Taken together, the vertical and lateral forces are managed by the horn springs 16 and the damper spring elements or bushings 22, resulting in damping of the resonant frequency of the steering wheel assembly 10. The following examples illustrate the stiffness calculations of the damper spring elements or bushings with respect to the present invention: Based on weight, the total mass of the airbag module assembly of 1.075 kg, the number of damper spring elements of three with a stiffness selected for each frequency of 20, 30 and 40 Hz at a lateral displacement, the following table results for fluorosilicone damper spring elements or bushings 22. Freq. (Hz) Mass (kg) Number of damper springs Stiffness / Gap (N / mm) Lateral displacement (mm) Lateral F / spring(N) at maximum deflection 20 1,075 3 5,65 1,0 5,64 30 1,075 3 12,78 1,0 12,72 40 1,075 3 22,59 1,0 22,59

[0020] In another aspect of the invention, the lateral fixings typically used within the horn switch 16 to ensure correct alignment of the horn switch 16 when placed within the support elements 330 are no longer required. In other words, the plurality of damper springs or elements 22 also function to locate each annular element 76, 176 of the horn switch 16. Accordingly, during assembly, when the horn switch 16 is positioned over the damper spring elements or sleeves 22, each of the annular elements 76, 176 of the horn switch 16 is aligned coaxially with a corresponding support element 330. As shown in the drawings of the Fig. 3, Fig. 4, Fig. 6, Fig. 7 and Fig.As shown in Figure 8, after assembly the support elements 330 are therefore each coaxially aligned with a corresponding annular horn switch element 76, 176 and a corresponding damper spring element or sleeve 22. After assembly, the lower horn switch housing 52 and the fitting 300 together act as a stop for the damper spring elements or sleeves 22, thereby limiting the lateral movement of the damper spring elements or sleeves preferably to one millimeter or less, or within the permissible strength limits.

[0021] As in the Fig. 6, Fig. 8 and Fig. 24 and in Fig.As shown in Figure 1, several damper spring isolators or spacers 24 correspond to the several damper spring elements or grommets 22 and are each elastically pre-tensioned between the base of the lower switch housing 52 and a lower section 22a of a respective damper spring element or grommet 22, thereby securing the damper spring element or grommet 22 within the support element 330. The damper spring isolators or spacers 24 assist in the installation of the driver airbag 14, as each spacer 24 enables and assists the sliding and snapping of the retaining wire 20 onto the pin or prong mounting element 34a, 34d, 34c. As shown, each isolator or spacer 24 is spaced laterally from the support, which limits the relative lateral movement and thus isolates the damper spring element or grommet 22 to ensure that it damps over the entire maximum range of lateral movement, in this case 1.0 mm.

[0022] As indicated above, the present invention significantly increases the effectiveness of a damping system to improve driver comfort when the steering wheel is gripped during operation of the associated vehicle. By suspending the airbag module 14 via the plurality of damper spring elements or bushings 22 and allowing lateral movement of the airbag module 14, the vibrations often transmitted to the steering wheel are attenuated and damped. Furthermore, the installation space required by the present damping system is relatively small compared to other known dampers in steering wheel systems. Finally, the relative weight of the present damping system is advantageously reduced compared to other known damping systems.

[0023] The description of the invention is merely exemplary, so variations that do not deviate from the core of the invention can be considered to be within its scope. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

[0024] Variations of the present invention are possible in light of the description given herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject matter of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention. It should therefore be understood that changes can be made to the specific embodiments described that remain within the full intended scope of the invention as defined by the following appended claims.

Claims

[1] An assembly comprising: a steering wheel (18) with a plurality of support elements (330); a plurality of damper spring elements or bushings (22), wherein each damper spring element or bushing (22) is held in a corresponding plurality of support elements (330); a motor vehicle component (14) that is attached to the steering wheel (18) and positioned on the plurality of damper spring elements or bushings (22); a plurality of mounting elements (34a-c) extending from the motor vehicle component (14) to attach the motor vehicle component (14) to the steering wheel (18), each mounting element (34a-c) extending through the plurality of support elements (330) and attached to the steering wheel (18); a fastening mechanism retaining wire (20) attached to the plurality of support elements (330), wherein the plurality of mounting elements (34a-c) are attached to the fastening mechanism retaining wire (20) to fasten the motor vehicle component (14) to the steering wheel (18); and a horn switch (16) which is located on the plurality of damper spring elements or grommets (22) and is held between the plurality of damper spring elements or grommets (22) and the motor vehicle component (14). [2] The assembly according to claim 1, wherein the motor vehicle component (14) is an airbag module (14). [3] The assembly according to claim 1, further comprising: a plurality of damper spring isolators or spacers (24), each of the damper spring isolators or spacers (24) being arranged between the fastening mechanism retaining wire (20) and a corresponding damper spring element or grommet (22). [4] The assembly according to claim 1, further comprising: an inner annular surface (332) that is contained in each of the support elements (330); a rib (334) formed on a central section of each of the inner annular surfaces (332); and a groove (26) formed on a central section of an outer circumference of each damper spring element or grommet (22), wherein the respective rib (334) is fitted into the respective groove (26) to hold each of the damper spring elements or grommets (22) in each corresponding support element (330). [5] An assembly comprising: a steering wheel (18) with a first plurality of ring-shaped support elements (330); a plurality of annular damper spring elements or sleeves (22), wherein each damper spring element or sleeve (22) is held in a corresponding annular support element (330) of the first plurality; a horn switch assembly (16) comprising an upper housing (50) and a lower switch housing (52), the lower switch housing comprising a second set of annular support elements (176), each of which is mounted over and coaxially aligned with a corresponding annular damper spring element or bushing (22) from the second set of annular support elements (176); and a motor vehicle component (14) that is positioned above the horn switch (16) and comprising a plurality of mounting elements (34a-c), each mounting element (34a-c) being attached to the steering wheel (18) to secure the motor vehicle component (14) to the steering wheel (18); and a fastening mechanism retaining wire (20) which is attached to the plurality of support elements (330), wherein each of the plurality of mounting elements (34a-c) is attached to the fastening mechanism retaining wire (20) to fasten the motor vehicle component (14) to the steering wheel (18). [6] The assembly according to claim 5, wherein the motor vehicle component (14) is an airbag module (14). [7] The assembly according to claim 5, further comprising: a plurality of damper spring isolators or spacers (24), each of the damper spring isolators or spacers (24) being arranged between the lower horn switch housing (52) and a corresponding damper spring element or grommet (22). [8] An assembly comprising: a steering wheel (18) with a plurality of hollow support elements (330); a plurality of damper spring elements or bushings (22), wherein each damper spring element or bushing (22) is held in a corresponding plurality of hollow support elements (330); and a motor vehicle component (14) which is attached to the steering wheel (18) and suspended from the plurality of damper spring elements or bushings (22); a plurality of mounting elements (34a-c) extending from the motor vehicle component (14) to attach the motor vehicle component (14) to the steering wheel (18), each mounting element (34a-c) extending through a corresponding plurality of hollow support elements (330) and being attached to the steering wheel (18); and a fastening mechanism retaining wire (20) which is pre-tensioned against the plurality of hollow support elements (330), wherein each of the plurality of mounting elements (34a-c) is attached to the fastening mechanism retaining wire (20) to fasten the motor vehicle component (14) to the steering wheel (18). [9] The assembly according to claim 8, further comprising: a horn switch (16) which is located on the plurality of damper spring elements or grommets (22) and is held between the plurality of damper spring elements or grommets (22) and the motor vehicle component (14). [10] The assembly according to claim 8, wherein the motor vehicle component (14) is an airbag module (14). [11] The assembly according to claim 9, further comprising: a plurality of damper spring element isolators or spacers (24), each of the isolators or spacers (24) being arranged between a lower horn switch housing (52) and a corresponding damper spring element or grommet (22). [12] The assembly according to claim 8, wherein the plurality of damper spring elements or sleeves (22) comprises a plurality of damper springs (22). [13] The assembly according to claim 8, wherein each of the several hollow support elements (330) has an annular surface (332) and each of the damper spring elements or sleeves (22) has a corresponding circumferential edge for fitting with one of the annular surfaces (332). [14] The assembly according to claim 13, further comprising: a radially inwardly extending ridge or rib (334) formed on each of the annular surfaces (332); and a radially outward extending strip or rib (334) formed on each of the circumferential edges for fitting with one of the radially inward extending strips or grooves (26), whereby a respective of the plurality of damper spring elements or sleeves (22) is held within a corresponding of the plurality of hollow support elements (330).

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