Abstract:
A vibration attenuation apparatus may include a mass element, a bracket, and an elastomeric member. The mass element may include a first aperture. The bracket may include first and second portions. The first portion may be attached to a structure that transmits an input vibration. The elastomeric member may engage the mass element and the second portion of the bracket and may suspend the mass element relative to the bracket. The elastomeric member may include a shaft portion and a barb portion. The shaft portion may engage the second portion of the bracket. The barb portion may engage the first aperture of the mass element. The elastomeric member may include properties allowing the mass element to move relative to the bracket in response to the input vibration at a frequency that reduces an amplitude of the input vibration.

Description:
FIELD 
     The present disclosure relates to a vibration attenuation system for a vehicle steering wheel, and more particularly to a mass-damper system having an elastomeric element. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Comfort and feel are important qualities in modern automotive vehicles. Noise, vibration and harshness (NVH) in a steering wheel of the vehicle can adversely affect the overall comfort and feel of the vehicle. Vibrations from the engine, suspension and/or other components of the vehicle may propagate through the steering system to the steering wheel and the driver&#39;s hands. Such vibrations can be uncomfortable and/or produce undesirable noise. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In one form, the present disclosure provides a vibration attenuation apparatus that may include a mass element, a bracket, and an elastomeric member. The mass element may include a first aperture. The bracket may include first and second portions. The first portion may be adapted to be attached to a structure that transmits an input vibration. The elastomeric member may engage the mass element and the second portion of the bracket and may suspend the mass element in spaced relation relative to the bracket. The elastomeric member may include a shaft portion and a barb portion. The shaft portion may engage the second portion of the bracket. The barb portion may engage the first aperture of the mass element. The elastomeric member may include properties allowing the mass element to move relative to the bracket in response to the input vibration at a frequency that reduces an amplitude of the input vibration. 
     In another form, the present disclosure provides a mass-damper assembly for a steering wheel. The mass-damper assembly may include a mass element, a bracket, and first and second elastomeric fasteners. The mass element may include a first engagement aperture and a second engagement aperture. The bracket may include a mounting arm for mounting the assembly to the steering wheel, a first support arm supporting the mass element, and a second support arm supporting the mass element. The first and second support arms may include first and second support apertures, respectively. The first elastomeric fastener may engage the first support aperture and the first engagement aperture. The second elastomeric fastener may engage the second support aperture and the second engagement aperture. The first and second elastomeric fasteners may maintain the mass element in a spaced apart relationship relative to the first and second support arms and allow the mass element to vibrate relative to the first and second support arms at a frequency that reduces an input vibration from the steering wheel. 
     In yet another form, the present disclosure provides a method that may include determining vibration characteristics of a steering wheel hub, tuning a plurality of elastomeric members to include predetermined structural properties based on the determined vibration characteristics of the steering wheel hub, securing a bracket to the steering wheel hub, suspending a mass from the bracket via the plurality of elastomeric members, and allowing the mass to vibrate relative to said bracket at a frequency that reduces vibration in the steering wheel hub. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a perspective view of a steering wheel including a mass-damper assembly according to the principles of the present disclosure; 
         FIG. 2  is a perspective view of the mass-damper assembly of  FIG. 1 ; 
         FIG. 3  is an exploded perspective view of the mass-damper assembly of  FIG. 1 ; 
         FIG. 4  is a perspective view of an elastomeric member of the mass-damper assembly according to the principles of the present disclosure; 
         FIG. 5  is a front view of the mass-damper assembly; and 
         FIG. 6  is a top view of the mass-damper assembly. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the several views of the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Throughout the description, example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     With reference to  FIGS. 1-6 , a mass-damper assembly  10  is provided and may include a bracket  12 , a mass element  14 , and a plurality of elastomeric fasteners  16 . The mass-damper assembly  10  may be mounted to a central hub area  18  of a steering wheel assembly  20 . As will be subsequently described, the plurality of elastomeric fasteners  16  may cooperate to suspend the mass element  14  relative to the bracket  12  and allow the mass element  14  to vibrate at a frequency and amplitude that reduces an input vibration that can be transmitted through the steering wheel assembly  20 . 
     The bracket  12  may be formed from a relatively thin plate or sheet of metal, plastic or other material and may include a body portion  22  having first and second mounting arms  24 ,  26  and first and second support arms  28 ,  30  extending therefrom. Each of the first and second mounting arms  24 ,  26  may include a mounting aperture  32  extending therethrough. Fasteners  34  may engage the mounting apertures  32  and corresponding threaded apertures in the hub  18  to secure the bracket  12  to the steering wheel assembly  20 . 
     The first and second support arms  28 ,  30  may extend from the body portion  22  in a first dimension X that is substantially perpendicular to body portion  22  and the first and second mounting arms  24 ,  26 . Each of the first and second support arms  28 ,  30  may include a first portion  40  and a second portion  42 . The first portion  40  may include a slot  44  extending at least partially across a length of the first portion  40 . The second portion  42  may extend outwardly from the first portion  40  to form a generally L-shaped cross section. Each of the second portions  42  may include an outwardly facing surface  49 , an inwardly facing surface  50 , and one or more support apertures  51  extending therethrough. 
     The mass element  14  may be a generally solid block formed from a metallic or polymeric material, for example, or any other suitable material. The particular material, size and/or shape of the mass element  14  may be selected to yield a predetermined weight, as will be subsequently described. The mass element  14  may include a first end  52 , a second end  54 , and a first side  56 . Each of the first and second ends  52 ,  54  may include one or more engagement apertures  58  extending inwardly therefrom in a second dimension Z. The engagement apertures  58  may be positioned relative to each other such that each of the plurality of engagement apertures  58  is aligned with a corresponding one of the support apertures  51  in the bracket  12 . While the engagement apertures  58  are described above as being disposed in the first and second ends  52 ,  54 , in other embodiments, the engagement apertures  58  may be disposed in any other suitable portion of the mass element  14 . 
     The first side  56  may include a plurality of apertures  60  extending through at least a portion of a thickness of the mass element  14  in a third dimension Y. Each of the plurality of apertures  60  can correspond to and be in communication with one of the engagement apertures  58 . While the plurality of apertures  60  are shown in the figures having a generally square shape, it will be appreciated that the plurality of apertures  60  could be round or otherwise suitably shaped. 
     The elastomeric fasteners  16  may be formed from a resiliently compressible and elastic material such as a natural rubber, silicone, or other elastomeric materials. Each of the elastomeric fasteners  16  may include a shaft portion  70 , a head portion  72 , and a barbed tip portion  74 . The head portion  72  may be disposed at a first end of the shaft portion  70  and the tip portion  74  may be disposed at a second end of the shaft portion  70 . The shaft portion  70  and the head portion  72  may be generally cylindrical members. As shown best in  FIG. 4 , the tip portion  74  may include a frusto-conical configuration with a first end  78  and a second end  80 . The first end  78  may include a larger perimeter than a diameter of the shaft portion  70  and the second end  80  may include a smaller perimeter than the perimeter of the first end  78 . Tip portion  74  may include a plurality of flat faces  76  that are angled relative to the shaft portion  70  and extend from the first end  78  to the second end  80 , as shown in  FIG. 4 . It should be appreciated that tip portion  74  may not include flat faces  76 , or may include fewer or more flat faces  76  than illustrated including, for example, two opposed flat faces  76 . While the mass-damper assembly  10  is shown in the figures having two pairs of opposing elastomeric fasteners  16 , in other embodiments, the mass-damper assembly  10  could have any number of elastomeric fasteners  16  arranged in any suitable configuration. 
     Each of the elastomeric fasteners  16  may be inserted through a corresponding one of the support apertures  51  and into a corresponding one of engagement apertures  58  such that the tip portion  74  is received in and engages a corresponding one of the apertures  60  and the head portion  72  abuts the outwardly facing surface  49  of the second portion  42  of the bracket  12 . The first end  78  of the barbed tip portion  74  may include a width or diameter of the perimeter that is greater than a diameter of the engagement aperture  58  such that the tip portion  74  is retained in aperture  60  after being inserted through engagement aperture  58 . In addition, the flat faces  76  may facilitate easier insertion of end  78  of tip portion  74  through the smaller diameter of engagement aperture  58 . 
     The elastomeric fasteners  16  engaging the apertures  60  proximate the first and second ends  52 ,  54  of the mass element  14 , respectively, may exert equal and opposite retaining forces on the mass element  14 , thereby retaining the mass element  14  in a suspended condition relative to the bracket  12  such that the mass element  14  is spaced apart from the inwardly facing surfaces  50  of the second portions  42  and the rest of the bracket  12 . The resiliently deflectable material and structure of the elastomeric fasteners  16  may allow the mass element  14  to vibrate or move relative to the bracket  12  in the first, second and/or third dimensions X, Z, Y and without contacting bracket  12 . 
     With reference to  FIGS. 1-6 , operation of the mass-damper assembly  10  and a method of attenuating vibration will be described in detail. As described above, the mass-damper assembly  10  may be mounted to the hub area  18  of the steering wheel assembly  20  and may reduce or attenuate vibrations in the steering wheel assembly  20 . The material and structure of the elastomeric fasteners  16  may be designed or tuned to allow the mass element  14  to vibrate at a predetermined frequency and amplitude in response to vibrations that may propagate through the steering wheel assembly  20  and into the bracket  12 . Such vibration of the mass element  14  relative to the bracket  12  may cancel or reduce these vibrations in the steering wheel assembly  20 . 
     The mass-damper assembly  10  for a particular steering wheel assembly  20  of a particular vehicle may be tuned based on calculated or measured vibration characteristics of the particular steering wheel assembly  20  such as a natural frequency and a frequency and amplitude of vibration at the hub area  18  during operation of the vehicle. Vibration in the hub area  18  having a first frequency can be cancelled or reduced by introducing vibration of the mass element  14  at a second frequency that is phase shifted relative to the first frequency. Therefore, based on the vibration characteristics of the steering wheel assembly  20 , desired vibration characteristics of the mass element  14  relative to the bracket  12  can be determined that will cancel or reduce an amplitude of vibration in the steering wheel assembly  20 . 
     To achieve the desired vibration characteristics of the mass element  14 , the weight of the mass element  14  and/or material and/or geometric properties of the elastomeric fasteners  16  may be adjusted or tuned such that the mass element  14  will vibrate at the second frequency in response to vibration of the hub  18  of the steering wheel assembly  20  at the first frequency. Such tuning may include selecting a material having a desired modulus of elasticity, modulus of rigidity, and/or Young&#39;s modulus, for example, and/or adjusting relative dimensions and/or geometry of the elastomeric fasteners  16 , for example, to facilitate vibration of a particular mass element  14  having a given weight. 
     Once the elastomeric fasteners  16  have been tuned for a given application, the mass-damper assembly  10  may be assembled and installed onto the hub area  18  of the steering wheel assembly  20 . During operation of the vehicle, vibrations from operation of various vehicle systems (e.g., the engine, suspension and/or steering system) and/or encounters with bumps in the road or driving surface may propagate to the hub area  18  and the bracket  12 . Such input vibrations (vibrating at a first frequency) may propagate through the first and second mounting arms  24 ,  26 , the body portion  22 , and the first and second support arms  28 ,  30 . Because the mass element  14  is suspended relative to the bracket  12  via the elastomeric fasteners  16 , the mass element  14  is allowed to vibrate at a second frequency in response to the input vibrations. As described above, the second frequency may be phase shifted relative to the first frequency, thereby cancelling or reducing the amplitude of the vibration in the steering wheel assembly  20 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.