Abstract:
A body mount for coupling a vehicle body to a vehicle frame is disclosed. The body mount includes a first member disposed on one side of the frame. The first member includes an elastomeric member with a plurality of pads formed about the periphery of the first member for defining a side to side and a fore/aft cushioning rate. The body mount also includes a second member disposed on an opposite side of the frame and operably coupled to the first member.

Description:
This is a continuation of application Ser. No. 09/256,445 filed Feb. 23, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention is directed to a body mount for an automotive vehicle or truck. More particularly, the present invention is directed to a body mount in which the vertical cushioning rate may be independently tuned in relation to the lateral cushioning rate. 
     2. Discussion 
     Automotive vehicles, and especially trucks are typically equipped with a body mount disposed between the vehicle body and the vehicle frame. The body mount provides additional cushioning between the vehicle body and frame. The body mount also serves to isolate the transmission of vibration energy and impact energy from the vehicle suspension and frame up through the vehicle body. 
     A variety of body mounts have been developed for different types of vehicle applications. Most of these body mount designs include an elastomeric member which is captured by a support structure for securing the body mount between the body and frame. The elastomeric member may be formed from a variety of plastic or rubber materials. 
     One example of a simple compression style body mount is a circular or annular elastomeric member which is secured to one or more metal plates. The durometer of the elastomeric member can be chosen for tailoring the characteristics of the body mount. However, this compression style mount is stiff vertically and soft laterally; including both side to side and fore/aft lateral directions. A particular disadvantage of this simple body mount design is that it does not provide firm lateral support for the vehicle body with respect to the frame. Thus, the vehicle body is not restricted from moving in the side to side and fore/aft directions with respect to the frame. This soft lateral support allows excessive motion laterally with respect to the vehicle frame which results in poor shake control of the vehicle. 
     An additional disadvantage of this compression style body mount design is that it produces a firm vertical cushioning rate which absorbs less energy and provides a harsher ride. Moreover, this body mount design typically has a vertical to lateral cushioning rate ratio of approximately 3:1 (vertical:lateral), allows only minimal tuning of the vertical rate with respect to the lateral rate, and limited options for designing the vertical rate independently from the lateral rate. Another disadvantage with typical prior art body mount designs is that the lateral cushioning rate is constant about the circumference of the mount. Thus, the side to side vehicle cushioning rate is identical to the fore/aft vehicle cushioning rate. Accordingly, this type of mount provides limited design flexibility to a vehicle ride control engineer in designing the mount for use on a variety of vehicles. 
     In the design of vehicle suspension systems, it is becoming more common to require the body mount to have a soft vertical cushioning rate for enhancing ride comfort, and a firm lateral (meaning both side to side and fore/aft) cushioning rate for providing increased vehicle stability and control. However, this desired feature typically requires a body mount in which the vertical cushioning rate can be tuned or designed independently from the lateral cushioning rate. 
     In view of the disadvantages associated with the prior art body mount designs, it is desirable to provide a body mount which has a soft vertical cushioning rate and a firm lateral cushioning rate. It is further desirable to provide a body mount which has a vertical to lateral cushioning rate of 1:2, 1:3 or greater, while still maintaining a soft vertical rate. As an additional feature, it is desirable to provide a body mount which allows the fore/aft lateral rate to be designed to be firmer or softer than the side to side lateral rate (or vice versa). Finally, it is desirable to provide a body mount with a one-way orientation or alignment feature forcing the mount to always be installed in the correct orientation within the vehicle. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a body mount for coupling a vehicle body to a vehicle frame. The body mount includes a first member disposed on one side of the frame. The first member includes an elastomeric member having a plurality of pads formed about the periphery of the first member for defining a lateral cushioning rate. The body mount also includes a second member disposed on an opposite side of the frame and operably coupled to the first member. As part of the present invention, the second member functions as a rebound cushion for the body mount. A structural collar may be disposed between the elastomeric member and the plurality of pads. The first member allows a vertical cushioning rate defined by the elastomeric member to be designed and/or tuned independently from the lateral cushioning rate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and appended claims, and by referencing the following drawings in which: 
     FIG. 1 is a cross-sectional view of an exemplary body on frame vehicle design utilizing the body mount of the present invention; 
     FIG. 2 is a perspective view of the body mount in accordance with a preferred embodiment of the present invention; 
     FIG. 3 is an exploded perspective view of the body mount of the present invention; 
     FIG. 4A is a cross-sectional view of the body mount in accordance with a preferred embodiment of the present invention; 
     FIG. 4B is a cross-sectional view of the body mount including an alternate lower member assembly in accordance with the present invention; 
     FIG. 5A is a perspective view of the upper cushion in accordance with an alternate embodiment of the present invention; 
     FIG. 5B is a perspective view of the upper cushion in accordance with an alternate embodiment of the present invention; 
     FIG. 6 is an exploded perspective view of the components forming the alternate lower member assembly of the present invention; 
     FIG. 7 is a cross-sectional view of the rebound cushion associated with the lower member assembly of FIG. 6; 
     FIG. 8 is a cross-sectional view of the inner cushion associated with the lower member assembly of FIG. 6; and 
     FIG. 9 is a cross-sectional view of the clamp disk associated with the lower member assembly of FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In accordance with the teachings of the present invention, a body mount having independent vertical and lateral cushion rates is disclosed. FIG. 1 illustrates an exemplary body on frame vehicle system  10  having a vehicle body  12  which is mounted to a vehicle frame  16  with a body mount  20 . A suitable retaining bolt  64  secures the body mount  20  between the body  12  and the frame  16 . The body mounts associated with the vehicle may have the same or different cushioning characteristics at different locations around the vehicle. 
     Referring now to FIGS. 2 and 3, the body mount  20  is shown according to a preferred embodiment of the present invention. The body mount  20  generally includes an upper member  22  and a lower member  24  which are disposed on opposite sides of the vehicle frame  16 . The upper member  22  includes the helmet  26  which fits over and through the upper cushion assembly  36 . The top portion of the helmet  26  is defined by four ears  28  having slightly flared ends, and four cutout portions  30 . The combination of ears  28  and cut out portions  30  allows the helmet  26  to be efficiently stamped from a square steel blank. The cutout portions  30  also serve to reduce undesirable weight by eliminating unnecessary metal. The helmet  26  also includes an elliptical stem  32  which forms an aperture for accommodating the retaining bolt  64 . The base of the stem  32  includes a pair of notches  34  which allow any water which collects within the stem  32  to properly drain through the body mount  20 . 
     The upper cushion  36  is formed around a circular metal collar  38  having an elliptical base  40  which fits within a corresponding elliptical aperture  18  formed within the vehicle frame  16 . This elliptical fit feature forces the mount to be installed in the correct orientation within the vehicle. An elastomeric inner cushion  42  is formed within the collar  38 . The shape of the inner cushion  42  defines an upper cushion leg  44  which is designed for engaging the inner surface of the helmet  26  when the body mount  20  is assembled. A set of four outer pads  46  are formed about the outside circumference of the upper cushion  36 . As disclosed, the outer pads  46  may be designed to include separately shaped opposing pairs of lateral pads  48  and fore/aft pads  50 . 
     The metal collar  38  may also be formed to have a square or rectangular outer dimension, also preferably with an elliptical base. As part of this configuration, the helmet  26  is also formed to have a corresponding square or rectangular outer dimension, and the inner surface of the four ears  28  have a flat surface for engaging the square or rectangular upper cushion  36 . A particular advantage of this alternate configuration is that a square or rectangular upper cushion  36  resists rotating with respect to a corresponding square or rectangular helmet  26 . 
     During the manufacturing of the upper cushion  36 , the metal collar  38  is coated with an adhesive material. The elastomeric material forming the inner cushion  42  and the outer pads  46  is then molded around the collar  38  into the desired size and shape. The adhesive material serves to permanently bond the elastomeric material to the collar  38 . The preferred method for forming the upper cushion  36  is through high pressure injection molding. However, it should be understood that other molding processes, such as transfer or compression molding processes can also be employed for forming the elastomeric components of the body mount. As part of the present invention, it is also contemplated that two different types or durometer of rubber or elastomeric material can be used for forming the upper cushion  36  and thus designing its dynamic properties. Alternatively, it is possible to mold the inner cushion  42  separately from the metal collar  38  and outer pads  46 , and then sub-assemble these components after molding. This technique easily allows two different types or durometer of rubber or elastomeric material to be employed for the inner cushion  42  and the outer pads  46 , allowing increased tuning flexibility. 
     The lower member  24  of the body mount  20  includes a rebound cushion  52  and a clamp disk  58 . The rebound cushion  52  has a complimentary elliptical aperture  54  in the top portion thereof for receiving the elliptical base  40  of the metal collar  38 . The preferred elastomeric material for the rebound cushion  52  is natural rubber or butyl. However, a variety of elastomeric materials can be used for the rebound cushion  52 . An annular lip  56  is molded into the bottom of the rebound cushion  52  which allows the clamp disk  58  to be snapped into position and retained by the rebound cushion  52 . As shown, the clamp disk  58  includes a central aperture  60  for receiving a suitable body mount fastener  64 . The clamp disk  58  also includes an opposing pair of drain holes  62  for allowing any water collecting within the center of the body mount  20 , or water draining through notches  34  to properly drain. 
     Turning now to FIG. 4A, the specific details associated with the upper member  22  and the lower member  24  of the body mount  20  are disclosed. The vertical and lateral cushion rates of the body mount  20  are primarily controlled through the upper member  22  and the shape of the upper cushion  36 . The preferred elastomeric material for the upper cushion  36  is butyl. However, natural rubber is also suitable for this application. The vertical cushion rate can be varied by changing the size and shape of the inner cushion  42  and the cushion leg  44 . The side to side and fore/aft components of the lateral cushion rate can be independently varied by changing the size and shape of the outer pads  46 . 
     FIG. 4A also shows that the outer pads  46  become pre-compressed between the collar  38  and ears  28  when the helmet  26  is fitted over the upper cushion  36 . Also shown is that the cushion leg  44  is pre-compressed through its contact with the inner surface of the helmet  26 . As part of the present invention, the dimensions of the outer pads  46  can be varied in order to change the amount of pre-compression of the elastomeric material disposed between the collar  38  and the helmet ears  28 . As t he distance between the collar  38  and the ears  28  is generally fixed, a wider or larger pad  46  will produce more pre-compression, and thus a firmer cushion rate. A narrower or smaller pad  46  will produce less pre-compression, and thus a softer cushion rate. Additionally, it is contemplated that the opposing pair of lateral pads  48  may have different dimensions than the opposing pair of fore/aft pads  50 , and therefore a different amount of pre-compression. 
     In a similar fashion, the size and shape of the inner cushion  42  and the cushion leg  44  can be designed for controlling the vertical rate of the mount. A larger cushion leg  44  will produce a firmer vertical cushion rate. A smaller cushion leg  44  will produce a softer vertical cushion rate. Additionally, the angle of the cushion leg  44  relative to the vehicle frame  16  can also be used to control the vertical cushion rate. As the angle with respect to the vehicle frame  16  increases, the vertical cushion rate also increases. As will be appreciated by one skilled in the art, these features of the outer pads  46  and the cushion leg  44  allow the lateral cushion rate of the body mount  20  to be designed or tuned independently from the vertical cushion rate. The design of the outer pads  46  can also be varied so that the side to side lateral cushion rate can be different than the fore/aft lateral cushion rate. 
     FIG. 4B discloses an alternate design of the body mount of the present invention. Specifically, body mount  20 ′ includes an upper member assembly  22 ′ which is substantially similar to upper member assembly  22 . The helmet  26 ′ and upper cushion  36 ′ can also accommodate the design of the lower member assembly  70  according to an alternate preferred embodiment of the present invention. As shown in FIGS. 4B and 6, the lower member assembly  70  generally includes a lower rebound cushion  72 , an inner cushion  74 , and a clamp disk  76  which can be pre-assembled as a unitary component prior to installation on the vehicle. As will be appreciated, the clamp disk  76  and its central body can take on a variety of configurations for engaging and aligning with the helmet stem  32 ′. 
     With reference to FIGS. 5A-5B, perspective views of upper cushions  36 A and  36 B are shown. The outer pads  46  of the upper cushions  36 A,  36 B are shown to have identical dimensions. However, as described above, pads  48  can have dimensions which are different from pads  50  for altering the lateral cushion rates. A particular feature of the upper cushion  36 A of FIG. 5A is that a portion of the elastomeric material, shown generally at  66 , forming the inner cushion  42  may be selectively removed. Additionally, as shown in FIG. 5B, four vertical grooves  68  may be cut, machined or molded into the remaining portion of the inner cushion  42 ′ and the cushion leg  44 ′. Preferably, the vertical grooves  68  are formed between the outer pads  46 ′ as shown. FIG. 5B also shows that a portion of the elastomeric material, shown at  66 ′, is also removed for tuning the vertical cushion rate. While not specifically shown, grooves  68  may take on a variety of shapes, including but not limited to, removing enough material for forming an aperture through the inner cushion  42 ′ and into the central aperture of the upper cushion  36 ′. 
     The purpose of these modifications is to remove a predetermined amount of the elastomeric material from the portion of the upper cushion  36 ′ which defines the vertical cushioning rate. As will be appreciated, this modification will produce an upper cushion  36 ′ and body mount  20  with a softer vertical rate. However, this modification will not affect the lateral cushioning rate because the outer pads  46 ′ are substantially isolated from the remaining elastomeric material of the inner cushion  42 ′ by the metal collar  38 . 
     The individual components forming the lower member assembly  70  associated with an alternate preferred embodiment of the present invention are shown in FIGS. 7-9. More specifically, FIG. 7 discloses a cross-sectional view of the rebound cushion  72 , which is also preferably injection molded from an elastomeric material such as a thermoplastic elastomer, natural rubber, EPDM or butyl. The structure of the rebound cushion  72  is defined by an outer wall  78 . An annular lip  80  is molded into the bottom of the outer wall  78  which allows the clamp disk  76  to be snapped into position and retained within the outer wall  78  of the lower rebound cushion  72 . 
     Through the injection molding process or a similar process, an outer channel  82  is formed between a molded inner wall  84  and the outer wall  78  of the rebound cushion  72 . As shown, the diameter of the annular lip  80  is less than that of the outer channel  82 . The molded inner wall  84  is also annular in shape, and forms a cylindrical inner cavity  86 . An inner channel  88  is also molded into the body of the rebound cushion  72 . The combination of the inner cavity  86  and the inner channel  88  function to maintain the inner cushion  74  in an optimal position. 
     A central aperture  90  which may be circular or elliptical in shape is formed through the body of the rebound cushion  72  for receiving the base  40  of a suitably designed upper cushion  36 . An annular groove  92  is molded around the outer circumference of the central aperture  90 . The annular groove  92  functions to locate or seat the inner cushion  74 . A cutout  94  is formed in the outer wall  78  of the rebound cushion  72 . The cutout  94  functions to reduce the required effort to insert the clamp disk  76 . 
     The particular features of the inner cushion  74  associated with the lower member assembly  70  are shown in cross section in FIG.  8 . The annular body of the inner cushion  74  includes alternating support ridges  94  and V-shaped notches  96  formed along the top and bottom surfaces. As shown, each support ridge  94  is disposed directly opposite a corresponding notch  96 . The alignment of the support ridges  94  and notches  96  functions to allow the inner cushion  74  to be compressed to approximately one half its full height during the rebound stroke of the body mount  20 ′. It is preferred that the elastomeric material used for the inner cushion  74  is selected to have a durometer which is softer than the durometer of the elastomeric material forming the rebound cushion  72 . This feature assists in producing a soft vertical cushioning rate. The inner cushion  74  is dimensioned to fit within the inner cavity  86  of the rebound cushion  72  yet still provide room to bulge and expand. The design of the inner cushion  74  can take on a variety of forms and is not limited to the disclosed shape or description herein, as the purpose of the inner cushion  74  is to provide a cushion which produces a soft vertical cushion rate. 
     The inner cushion  74  is retained within the rebound cushion  72  by the metal clamp disk  76  having its outside diameter defined by an annular wall  98 . During the stamping process, an annular channel  100  is formed within the clamp disk  76  which assists the inner cushion  74  in maintaining its proper shape during compression. A central aperture  102  is also formed within the clamp disk  76  for receiving a suitable body mount fastener  64 . The clamp disk  76  also includes a pair of opposing drain holes  104  for allowing any water collecting within the center of the body mount  20 ′ to properly drain. As will be appreciated, the clamp disk  76  can take on a variety of configurations for aligning the inner cushion  74 , and engaging and aligning with the helmet stem  32 ′. 
     The complete assembly of body mount  20 ′, including the lower member assembly  70  is shown in FIG.  4 B. As will be appreciated, the lower member assembly  70  provides a firm lateral cushion rate due in part because the rebound cushion  72  has a stiff outer wall  78  for resisting the lateral movements of the clamp disk  76 . Additionally, the lower member assembly  70  provides a soft vertical cushion rate because of the lower compression resistance provided by the softer durometer of the inner cushion  74 , and because the annular wall  98  of the clamp disk  76  is able to move vertically within the outer channel  82  of the rebound cushion  72 . Thus, the features of body mount  20 ′ also allow the vertical cushioning rate to be higher than the lateral cushioning rate. 
     The foregoing discussion discloses and describes exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.