Abstract:
A steering wheel of hub-and-spoke configuration including a hub, a plurality of spokes and a ring portion, wherein the spokes place the ring into material contact with the hub. The first spoke of the steering wheel includes an armature support, while the second spoke of the steering wheel does not include an armature support. The second spoke may be primarily made from polyurethane foam. The second spoke may be located at a lower portion of the steering wheel, and the lower portion of the steering wheel deforms more easily than a portion of the steering wheel proximate to the first spoke.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Hub-and-spoke automobile steering wheels with three or more spokes are aesthetically pleasing and desirable to perspective automobile purchasers. Moreover, steering wheels having spokes that project downward from the hub (as referenced when the steering wheel is positioned for “straight ahead” driving) are also appealing. Thus, in the case of a three spoke steering wheel, many designs would have a spoke located at about the 6 o&#39;clock position with respect to the steering wheel. In the case of four spoke steering wheel, many designs would have one or two of the spokes located between the 3 o&#39;clock and 9 o&#39;clock positions of the steering wheel. Hereinafter, spokes located between about the 3 o&#39;clock and about the 9 o&#39;clock position will be referred to as “lower spokes.” 
         [0002]      FIG. 1  shows an explanatory embodiment of a four spoke steering wheel, where two of the spokes (spokes  130 ) are lower spokes.  FIG. 1  shows a steering wheel  100  with a ring portion  110  and four spokes ( 120 ,  130 ) which connect the ring portion  110  to a hub portion  145 . As may be seen, the steering wheel  100  includes a frame  105 . The elements making up the frame  105  (elements  115 ,  125 ,  135 ,  145 , etc., discussed in greater detail below) are typically fabricated from strong, relatively high load-bearing materials, such as by way of example and not by way of limitation, aluminum, steel, harden plastic, graphic epoxy, reinforced fiberglass etc. These elements are further typically of a design to improve their load-bearing features while reducing weight/material costs (e.g., utilizing “C,” “U,” and “I” shaped elements and aligning the elements so as to place the higher load-bearing geometries in line with the direction of expected higher loads, etc.) In particular, armature supports  125  and  135  are typically of a structural design such that these elements may transfer a substantial amount of steering torque (or in some cases all of the steering torque) that may be applied to the ring  110  to the hub  145 . Such a steering wheel design presents an aesthetically pleasing as well as a structurally sound steering wheel which may be used to control the direction of an automobile.  
         [0003]     Analysis of simulated crash data for hub-and-spoke steering wheels with the three and four spokes, where one or more of the spokes are located at a lower portion of the steering wheel (i.e., one or more spokes are lower spokes) shows that in the event of a rapid deceleration, such as may occur in a head-on collision with a concrete barrier, a driver&#39;s upper body, in particular, a driver&#39;s chest, may impact the lower portion of the steering wheel. Since such impact may be unavoidable in certain crash scenarios, the present inventors have determined that it is desirable that the steering wheel absorb at least some of the energy from the impact of the driver&#39;s chest onto the steering wheel. Such impact absorption may reduce injury to the driver. However, in a steering wheel having the configuration shown in  FIG. 1 , where the frame  105  of the steering wheel  100  includes armature supports  125  and  135  (i.e., structural members of significant strength such that significant torque may be applied from the wheel to the hub through the supports) in the spokes  120  and  130 , respectively, the ability of the steering wheel (in particular, the lower portion of the steering wheel) to absorb energy is somewhat limited. Because of the structural rigidity of the armature supports  125 / 135  of the spokes  120 / 130 , the lower portion of the steering wheel will absorb less energy. That is, due to the armature supports  125 / 135  of the spokes  120 / 130 , which increase the structural rigidity of the lower portion of the steering wheel  100 , a driver occupant may be injured in a crash if his or her body impacts the lower portion of the steering wheel because this portion is structurally reinforced by the armature supports,  125 / 135 .  
       SUMMARY OF THE INVENTION  
       [0004]     One embodiment of the invention relates to a steering wheel of hub-and-spoke configuration, comprising a hub, a plurality of spokes; and a ring portion, wherein the spokes place the ring into material contact with the hub, wherein a first spoke includes an armature support, and wherein a second spoke does not include an armature support. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a schematic representation of a steering wheel of four spoke configuration with armature supports in each spoke.  
         [0006]      FIG. 2  is a schematic representation of a steering wheel of four spoke configuration with armature supports only in the upper spokes.  
         [0007]      FIG. 3  is a schematic representation of the frame of the steering wheel of  FIG. 2  with the polyurethane foam removed. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0008]     In a first embodiment of the invention, as is exemplary depicted in  FIGS. 2 and 3 , there is a steering wheel  200  comprising a frame  205 . The frame  205  includes a ring  215 , armature supports  225 , and a hub  245 . As may be seen from the Figs., the ring portion  215 , the armature supports  225  and the hub  245  are materially connected to each other. In the exemplary embodiment depicted in  FIG. 2 , the frame  205  is substantially covered by polyurethane foam  50  thus enhancing the feel of the steering wheel, the look of the steering wheel, and providing a barrier between any sharp edges located on the frame and the driver.  FIG. 3  depicts the frame  205  of the steering wheel  200  without the polyurethane foam coating  50 . (It is noted that  FIGS. 2 and 3  schematically depict a steering wheel/steering wheel frame in a reference where the steering wheel would be positioned when the vehicle is driving straight.)  
         [0009]     As may be seen from  FIG. 2 , the steering wheel  200  includes lower spokes  230  located between about the 4 and 5 o&#39;clock positions and between about the 7 and 8 o&#39;clock positions. As may be seen from  FIGS. 2 and 3 , the frame  205  of the steering wheel  200 , according to a first embodiment of the invention, does not have armature supports in the lower spokes  230 , whereas armature supports  225  are present in the upper spokes  220 . That is, unlike the upper spokes  220  that have armature supports, there are no armature supports in the lower spokes  230 .  
         [0010]     As may be readily seen from  FIGS. 2 and 3 , other than the armature supports  225  of the upper spokes  220 , the bottom half of the ring portion  210  of the steering wheel is not supported by armature supports, unlike the steering wheel of  FIG. 1 . Thus, in the event that a driver impacts the lower portion of the ring portion  210  of the steering wheel  200  due to a sudden deceleration resulting from, for example, a head-on collusion of the vehicle, the bottom portion of the ring portion  210  is much more likely to effectively deflect in a manner that effectively absorbs at least some of the kinetic energy of the driver&#39;s chest. Indeed, the lower portion of the ring  210  is much more likely to substantially deform than the portions of the ring proximate the upper spokes  220 . Thus, the driver is less likely to be seriously injured because the bottom portion of the ring portion  210  of the steering wheel  200  may deflect more due to a absence of armature supports in the lower spokes.  
         [0011]     As may be seen from  FIG. 2 , the lower spokes  230 , while not serving as significant structural members, are still present. This allows for the aesthetic benefits of a four spoke steering wheel to be obtained, while providing for a steering wheel of improved deflection capabilities. In a first embodiment according to  FIG. 2 , the lower spokes  230  are entirely formed by polyurethane foam columns (which, in this embodiment, is the same type of foam that covers the upper armatures  225  of the upper spokes  220 ). That is, in the embodiment of  FIG. 2 , if a cross-section A-A is taken about normal to the longitudinal axis of the spokes  230 , the material of that cross-section would be entirely polyurethane foam. In a first embodiment of the invention, spokes  230  at section A-A are solid in that there are no gaps (other than those naturally occurring due to the use of a “foam”) present in the spokes. Thus, the material at a geometric center of the cross-section A-A of the spoke  230  taken substantially normal to the longitudinal axis of the spokes  230  is polyurethane foam.  
         [0012]     As is discussed above and will be discussed in greater detail below, the presence of the lower spokes in the first embodiment is due to a desire to provide an aesthetically pleasing steering wheel that has the above mentioned advantages with respect to driver impact on the lower portion of the steering wheel. It is noted that in other embodiments of the present invention, lower spokes  230  may be used to support control input devices such as a cruise control input device, radio volume control device, etc., and/or may be used to shield wiring extending from the hub to the lower portion of the ring portion.  
         [0013]     In some embodiments of the present invention, the spokes  230  in general, and the material of the cross-section A-A of the spokes  230  in particular, may primarily be made from polyurethane foam while also including other material such as, for example, rubber, soft plastics, etc., which will still allow for an effectively deformable lower ring portion.  
         [0014]     As noted above, in some embodiments of the invention, the spokes  230  are substantially solid. In other embodiments of the present invention, the spokes  230  may be hollow. That is, by way of example, a cavity may extend parallel to the longitudinal axis to the spokes  230 . In some embodiments of the present invention, this cavity may be centered at about a geometric center of the cross-section A-A, while in other embodiments of the present invention, this cavity may be located in other locations. In yet other embodiments of the invention, a cavity of a spherical shape and/or other shapes may be present such that the cavity does not necessarily extend along the longitudinal axis of the spokes  230 .  
         [0015]     It is noted that in some embodiments in the present invention, a material having a high modulus of elasticity, such as, for example, aluminum, steel, etc., may be included in the spokes  230 . (For example, as noted above, wires may run through the spokes  230 .) As long as the material having a high modulus of elasticity does not add any substantial structural rigidity to the lower spokes  230 , the spokes  230  may be considered to be made up of material that substantially comprises polyurethane foam.  
         [0016]     As noted above, the purpose of the upper spokes  220 , or more accurately, the purpose of the armature supports  225  in the upper spokes  220  of the wheel  200 , is to transfer steering torque imparted to the ring  210  of the wheel  200  during driving, into the hub  245  such that the automobile may be steered. It is noted that in some embodiments of the present invention, it is expected that a limited amount (a relatively small and insubstantial amount) of steering torque may be transmitted through the lower spokes  230  into the hub  245 . That is, even though the lower spokes  230  connecting the hub  245  to the lower portions of the steering wheel ring portion  210  are made from polyurethane foam, the polyurethane foam spokes  230  will still transmit “trace” amounts of torque to the hub  245  owing basic principles relating to material science.  
         [0017]     Other structural details of the spokes  220 / 230  of the steering wheel  200  will now be described, but first a hypothetical structural analysis of the steering wheel  200  will be presented to provide a frame of reference for the teachings regarding to these other structural details below. If the ring  210  where to be hypothetically removed from the steering wheel  200  and a torque were applied at locations on the spokes  220 / 230  where the spokes interface (or, more accurately, formerly interfaced) with the ring portion  210 , torque would be transmitted through both the upper spokes  220  owing to the support armatures  225  and through the lower spokes  230  owing to the polyurethane foam construction of the spokes  230 . Such hypothetical application of torque will be hereinafter referred to as “individual spoke torque application.” 
         [0018]     In such hypothetical torque applications, the amount of torque that could be applied to the hub would be much greater in the case of the upper spokes  220  then in the case of the lower spokes  230 . That is, because the torque transferring material of the lower spokes  230  substantially comprises polyurethane foam, while the torque transferring material of the upper spokes  220  comprises steel, aluminum and/or harden plastic due to the armature supports  225 , the upper spokes may transfer a much greater torque to the hub than the lower spokes. Thus accordingly to some embodiments of the present invention, the modulus of elasticity of the torque transferring material of the upper spokes  220  is about an order of magnitude or more than the torque transferring material of the lower spokes  230 .  
         [0019]     Still further, another way of considering the structural features of the spokes  220  and  230  is to analyze the separate torque transferring features of the spokes irrespective to each other. In this regard, torque transferring elements that transfer a substantial amount of individual spoke torque application to the hub, with respect to an individual torque, is an armature support in the upper spokes,  220 , while the element that transfers a substantial amount of individual spoke torque application to the hub (again relative to the spoke) is a polyurethane foam element for the lower spokes  230 .  
         [0020]     As may be readily seen, the upper spokes  220 , during normal operation of the steering wheel  200 , would likely transfer between about 40 and 55% of an applied steering torque applied to the ring to the hub. That is, assuming that the design and manufacture of the wheel  200  provided for about even distributions of load and torque, the spokes  220  would transfer virtually all of the steering torque to the hub in about equal amounts. Thus, if the applied steering torque is divided by two, each spoke would transfer about half of the total applied steering torque to the hub. However, in some embodiments, as noted above, it is expected that the lower spokes  230  may transfer a limited amount of the steering torque to the hub. Therefore some designs of the steering wheel  200  may include upper spokes that are adapted to transfer a substantial amount of the steering torque applied to the ring  210  to the hub  245 , and lower spokes  230  adapted to transfer a minimal amount of the steering torque applied to the ring  210  to the hub  245 . Such a design is in keeping with one of the advantages of the invention, which is to provide a steering wheel that has a lower portion that absorbs energy from the impact of a vehicle driver with the steering wheel.  
         [0021]     Yet another way of analyzing the steering wheel  200  of a first embodiment of the invention is to compare the torque at which an upper spoke with an armature  225  will fail to that of a failure torque of a lower spoke. Thus, in some designs, each upper spoke is adapted to transfer about 100% of a first torque to the hub before failing, while the lower spokes  230  in some embodiments, would be such that each of the spokes would be adapted to transfer no more than about 5% of the first torque to the hub before failure. In yet other embodiments of the present invention the lower spokes would be adapted to fail at about 2% of the first torque. Indeed in some embodiments the lower spokes would fail at 1% of the first torque. It is noted that by “fail,” it is meant that the spokes deform in a substantial manner rendering the steering wheel unusable for continued typical use.  
         [0022]     In some embodiments of the present invention, the upper spokes are adapted to withstand at least about 200 foot-pounds of torque transferred to the hub through each upper spoke without substantial deformation. Conversely, each lower spoke is adapted to substantially deform under an application of about 40 foot-pounds of torque applied through the lower spoke to the hub.  
         [0023]     It is noted that while in the first embodiment of the invention, polyurethane foam is used to form the lower spokes  230 . However, in other embodiments of the present invention, a wide variety of soft synthetic resins may be used. Still further, other naturally occurring and/or synthetic materials may be used to make the spokes providing that the lower portion of the ring  210  absorbs sufficient energy as detailed above.  
         [0024]     Given the disclosure of the present invention, one versed in the art would appreciate that there are other embodiments and modifications within the scope and spirit of the present invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention.