Abstract:
The present invention concerns an air spring and jounce shock assembly for use in an automotive vehicle suspension system. The assembly may include a base adapted to be mounted on one of an axle assembly and a suspension component, a top cap adapted to be attached to a vehicle frame, and a diaphragm disposed between and attached to the base and the top cap, with the diaphragm including an inner surface defining a first portion of a compressed air cavity. A jounce shock reaction surface defines a second portion of the compressed air cavity and is included in a one of the top cap and the base. A jounce shock assembly is disposed in the air cavity in opposed relation to the jounce shock reaction surface and affixed to an other of the top cap and the base, with the jounce shock assembly including a body, affixed to the other of the top cap and the base and defining a compressed gas chamber, and a rod having a first end portion in the compressed gas chamber sealably engaged with and slidable relative to the body and a second end portion telescopically slidable from the body and located to selectively engage the jounce shock reaction surface.

Description:
BACKGROUND OF INVENTION  
       [0001]     The present invention relates generally to vehicle suspension systems and, in particular, to vehicle suspension systems employing air springs.  
         [0002]     Some automobile and truck suspension systems include air springs mounted between an axle assembly (or suspension system component) and a vehicle frame (or body). Air springs typically include a base, mounted to the axle assembly, a top cap, mounted to the frame, and a diaphragm disposed between and attached to the base and the cap. The diaphragm defines an inflatable compressed air cavity that is compressible during operation of the vehicle to smooth the vehicle&#39;s ride.  
         [0003]     Vehicles equipped with the air springs also typically include jounce bumpers, which are blocks of rubber mounted between the vehicle suspension system and frame that prevent a vehicle from bottoming out during operation. That is, the rubber jounce bumpers are sandwiched between the suspension components and frame to prevent hard metal to metal contact. Mounting jounce bumpers and the air springs separately, however, requires a larger amount of packaging space and comprises more separate parts than is desirable, and also increases the complexity of assembly for the suspension system. Moreover, jounce bumpers tend to create a rebound spring reaction, referred to as kickback, that is not desirable since they only provide a relatively brief, hard impact without appreciable damping.  
         [0004]     Some have suggested mounting of integrating the jounce bumpers inside the air springs. However, this does not alleviate the undesired kickback phenomenon. It is desirable, therefore, to provide a vehicle suspension system that provides both an air spring and a jounce bumper function, and which is packaged in a relatively small amount of space, while also alleviating kickback concerns.  
       SUMMARY OF INVENTION  
       [0005]     An embodiment of the present invention concerns an air spring and jounce shock assembly for use in a vehicle suspension system. The assembly may include a base adapted to be mounted on one of an axle assembly and a suspension component, a top cap adapted to be attached to a vehicle frame, and a diaphragm disposed between and attached to the base and the top cap, with the diaphragm including an inner surface defining a first portion of a compressed air cavity. The assembly may also include a jounce shock reaction surface defining a second portion of the compressed air cavity and included in a one of the top cap and the base, and a jounce shock assembly disposed in the air cavity in opposed relation to the jounce shock reaction surface and affixed to an other of the top cap and the base, with the jounce shock assembly including a body, affixed to the other of the top cap and the base and defining a compressed gas chamber, and a rod having a first end portion in the compressed gas chamber sealably engaged with and slidable relative to the body and a second end portion telescopically slidable from the body and located to selectively engage the jounce shock reaction surface.  
         [0006]     An advantage of an embodiment of the present invention is the reduced packaging space needed due to the incorporation of a jounce shock member into an air spring assembly.  
         [0007]     The assembly in accordance with the present invention advantageously reduces vehicle complexity by reducing the number of parts mounted to the vehicle suspension and frame. This may also reduce assembly complexity, and the number of different parts on hand at a vehicle assembly plant.  
         [0008]     Another advantage of an embodiment of the present invention is that the jounce shock is protected from the external environment.  
         [0009]     Additionally, the assembly may be interchangeable with conventional air spring configurations, thus providing an easy retrofit of the conventional air spring by replacing it with an integral air spring and jounce shock assembly. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0010]      FIG. 1  is a partial cross sectional view of an air spring and jounce shock assembly in accordance with a first embodiment of the present invention.  
         [0011]      FIG. 2  is a partial cross sectional view of a second embodiment of an air spring and jounce shock assembly in accordance with the present invention.  
         [0012]      FIG. 3  is a partial cross sectional view of a third embodiment of an air spring and jounce shock assembly in accordance with the present invention.  
         [0013]      FIG. 4  is a partial cross sectional view of a fourth embodiment of an air spring and jounce shock assembly in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0014]     Referring now to  FIG. 1 , an air spring and jounce shock assembly in accordance with the present invention is indicated generally at  100 . The assembly  100  includes an air spring base  102  that is attached to a vehicle axle assembly (or other suspension component, such as a control arm)  104 . The base  102  is preferably formed of steel, aluminum, a composite material, or the like. The r assembly  100  also includes an air spring top cap  106  that is attached to a vehicle frame (or body, which will be considered the same as a frame in terms of describing and defining the invention herein)  108 . The cap  106  is also preferably formed of steel, aluminum, a composite material, or the like. The term vehicle frame as used herein includes the frame itself and any bracket affixed to the frame to mounting an air spring thereto. For a unibody vehicle, the air spring may be mounted to the body or a bracket affixed to the body.  
         [0015]     An air spring diaphragm  110  is attached to and seals between the base  102  and the top cap  106 . The diaphragm  110  includes an inner surface  111  that defines a compressed air cavity  116  between the base  102  and the top cap  106 . The diaphragm  110  is preferably formed of an elastomeric material such as rubber or the like, and is attached to the top cap  106  at an upper edge thereof by an upper clamp or spring  112  and to the base  102  by a lower clamp or spring  114  at a lower edge thereof. The top cap  106  includes an air feed line  120  extending therethrough that is connected to a source of compressed air (not shown) for supplying compressed air to the compressed air cavity  116  in a manner known to those skilled in the art. Of course, relative movement between the axle assembly  104  and frame  108  causes relative movement between the air spring base  102  and the top cap  106 . When the base  102  and the cap  106  move towards each other, the air trapped in the compressed air cavity  116  compresses, resulting in a greater resistance to continued relative movement between the axle assembly  104  and the frame  108 .  
         [0016]     The air spring base  102  includes a support  118  to which a jounce shock assembly  124  is mounted. The jounce shock assembly  124  extends into the cavity  116 . In this embodiment, the jounce shock assembly  124  includes a body  126  that is preferably press-fit into the support  118 , with the body  126  including an outwardly extending flange  128  that abuts an upper surface of the support  118 . As an alternative, the body may be integral with the air spring base  102 . So, when referring to a body being mounted on or affixed to the base or top cap herein, this also includes the body being integral with the base or top cap. The body  126  is hollow and defines a chamber  127 . A jounce shock charging line  134  extends through a lower wall  129  of the body  126  into the chamber  127  and is connected to a supply of compressed gas, or more preferably a compressed gas/oil mixture. While the charging line  134  may be connected to a supply of compressed gas during vehicle operation, if so desired, it is more preferable that the charging line  134  is only connected to a supply of compressed gas—and hence the chamber  127  charged—during initial assembly or when being serviced.  
         [0017]     The jounce shock assembly  124  also includes a rod  130  that is telescopically disposed in the body  126  and extends from an upper end thereof. The rod  130  has a piston  131  connected to its lower end that seals around the periphery of the chamber  127  while allowing the rod  130  to slide up and down relative to the body  126 . As an alternative, the rod  130  may have a diameter generally matching that of the chamber  127 , with the lower portion of the rod  130 , in effect, forming an integral piston. A piston stop  138  is fixed to the body  126  and located in the chamber  127  to limit the upward travel of the piston  131 . The chamber  127  in the body  126 , along with the piston  131  will trap a compressed gas/oil mixture. The compressed gas/oil mixture will cause the rod  130  to move upward until the piston  131  is seated against the stop  138 .  
         [0018]     The rod  130  also has a rod cap  132  with a blunt shape mounted on an upper free end. The top cap  106  includes a reaction surface  122  facing the rod cap  132 , preferably with a reaction feature  123  that is shaped to substantially conform to the rod cap  132 . Under normal operating conditions, the piston stop  138  determines the rest position of the piston  131 , with the length of the rod  130  set so that there is a gap between the cap  132  of the rod  130  and the reaction surface  122 . While the reaction feature  123  is shown extending over only a portion of the reaction surface  122 , it may, if so desired, extend across the entire reaction surface  122 .  
         [0019]     The operation of the air spring and jounce shock assembly  100  will now be described. As the vehicle is driven under normal loading along relatively smooth terrain, the axle assembly  104  and frame  108  will move relative to one another, compressing and decompressing the air in the compressed air cavity  116 , which supports the top cap  106  relative to the base  102 . The jounce shock assembly  124  is sized and positioned so that the rod cap  132  remains spaced from the reaction surface  122  during the normal loading conditions. Accordingly, the air spring and jounce shock assembly  100  acts essentially as a conventional air spring under these driving conditions.  
         [0020]     On the other hand, when the vehicle encounters terrain that causes a large energy input from an impact—such as a pothole or a curb—the air spring diaphragm  110  may allow the axle assembly  104  to drive the base  102  toward the top cap  106  and frame  108  to an extent that the rod cap  132  contacts the reaction surface  122 . Any further movement of the base  102  toward the top cap  106  will now cause the reaction surface  122  to drive the rod  130  into the pressurized chamber  127 . The substantial increase in the effective damping and suspension rate for this air spring and jounce shock assembly  100  over this last portion of travel will prevent the vehicle suspension from bottoming out on the frame. This eliminates the need for separate jounce bumpers and packaging spaced for them on the vehicle.  
         [0021]     In effect, the jounce shock assembly  124  acts as a supplementary shock absorber that adds a significant amount of damping and suspension rate in the jounce (compression) direction over only a critical portion of the suspension travel. Moreover, since the jounce shock assembly  124  behaves more like a shock absorbing member, the kickback associated with conventional rubber jounce bumpers is almost eliminated. To put it another way, during jounce, the air spring and jounce shock assembly  100  provides significant spring rate growth, with the primary force generated by the jounce shock assembly  124  being via the gas spring created by the piston  131  in the charge chamber  127 . In rebound, the jounce shock assembly  124  is critically damped so that it decouples from the reaction surface  122  and dissipates the stored energy as heat.  
         [0022]     Referring now to  FIG. 2 , a second embodiment of an air spring and jounce shock assembly in accordance with the present invention is indicated generally at  200 . The assembly  200  includes an air spring base  202  that is attached to a vehicle axle assembly (or other suspension component, such as a control arm)  204 . The assembly  200  also includes an air spring top cap  206  that is attached to a vehicle frame  208 . An air spring diaphragm  210  is attached to and seals between the base  202  and the top cap  206 . The diaphragm  210  includes an inner surface  211  that defines a compressed air cavity  216  between the base  202  and the top cap  206 . The diaphragm  210  is preferably attached to the top cap  206  at an upper edge thereof by an upper clamp or spring  212  and to the base  202  by a lower clamp or spring  214  at a lower edge thereof. The top cap  206  includes an air feed line  220  extending therethrough that is connected to a source of compressed air (not shown).  
         [0023]     The air spring top cap  206  includes a support  218  to which a jounce shock assembly  224  is mounted. The jounce shock assembly  224  extends into the cavity  216 . In this embodiment, the jounce shock assembly  224  includes a body  226  that is preferably press-fit into the support  218 . The body  226  may include an outwardly extending flange (not shown), similar to the flange  128  shown in  FIG. 1 , that abuts an lower surface of the top cap  206  when the body  226  is press-fit in the support  218 . The body  226  is hollow and defines a chamber (not shown in  FIG. 2 ). A jounce shock charging line  234  extends through a lower wall of the body  226  into the chamber and is connected to a supply of compressed gas, or more preferably a compressed gas/oil mixture.  
         [0024]     The jounce shock assembly  224  also includes a rod  230  that is telescopically disposed in the body  226  and extends from a lower end thereof. The rod  230  has a piston (not shown in  FIG. 2 ) connected to its upper end that seals around the periphery of the chamber while allowing the rod  230  to slide up and down relative to the body  226 . As an alternative, the rod  230  may have a diameter generally matching that of the chamber, with the upper portion of the rod  230 , in effect, forming an integral piston. A piston stop (not shown in  FIG. 2 ) is fixed to the body  226  and located in the chamber to limit the downward travel of the rod  230 . The chamber in the body  226 , along with the piston will trap a compressed gas/oil mixture. The compressed gas/oil mixture will cause the rod  230  to move downward until the piston is seated against the stop.  
         [0025]     The rod  230  also has a blunt-shaped rod cap  232  mounted on a lower free end. The air spring base  202  includes a reaction surface  222  facing the rod cap  232 , preferably with a reaction feature  223  that is shaped to substantially conform to the rod cap  232 . Under normal operating conditions, the piston stop determines: the rest position of the piston, with the length of the rod  230  set so that there is a gap between the cap  232  of the rod  230  and the reaction surface  222 .  
         [0026]     The operation of the air spring and jounce shock assembly  200  is similar to that of the first embodiment. As the vehicle is driven under normal loading along relatively smooth terrain, the axle assembly  204  and frame  208  will move relative to one another, compressing and decompressing the air in the compressed air cavity  216 , which supports the top cap  206  relative to the base  202 . The jounce shock assembly  224  is sized and positioned so that the rod cap  232  remains spaced from the reaction surface  222  during the normal loading conditions. Accordingly, the air spring and jounce shock assembly  200  acts essentially as a conventional air spring under these driving conditions.  
         [0027]     On the other hand, when the vehicle encounters terrain that causes a large energy input from an impact—such as a pothole or a curb—the air spring diaphragm  210  may allow the axle assembly  204  to drive the base  202  toward the top cap  206  and frame  208  to an extent that the rod cap  232  contacts the reaction surface  222 . Any further movement of the base  202  toward the top cap  206  will now cause the reaction surface  222  to drive the rod  230  into the pressurized chamber. The substantial increase in the effective damping and suspension rate for this air spring and jounce shock assembly  200  over this last portion of travel Will prevent the vehicle suspension from bottoming out on the frame. This eliminates the need for separate jounce bumpers (and packaging spaced for them) on the vehicle.  
         [0028]     Referring now to  FIG. 3 , a third embodiment of an air spring and jounce shock assembly in accordance with the present invention is indicated generally at  300 . The assembly  300  includes an air spring base  302  that is attached to a vehicle axle assembly (or other suspension component, such as a control arm)  304 . The assembly  300  also includes an air spring top cap  306  that is attached to a vehicle frame  308 . An air spring diaphragm  310  is attached to and seals between the base  302  and the top cap  306 . The diaphragm  310  includes an inner surface  311  that defines a compressed air cavity  316  between the base  302  and the top cap  306 . The diaphragm  310  is preferably attached to the top cap  306  at an upper edge thereof by an upper clamp or spring (not shown in  FIG. 3 ) and to the base  302  by a lower clamp or spring (not shown in  FIG. 3 ) at a lower edge thereof. The top cap  306  includes an air feed line  320  extending therethrough that is connected to a source of compressed air (not shown).  
         [0029]     The air spring top cap  306  includes a support  318  to which a jounce shock assembly  324  is mounted. The jounce shock assembly  324  extends into the cavity  316 . In this embodiment, the jounce shock assembly  324  includes a body  326  that is preferably press-fit into the support  318 . The body  326  may include an outwardly extending flange (not shown), similar to the flange  128  shown in  FIG. 1 , that abuts an lower surface of the top cap  306  when the body  326  is press-fit in the support  318 . The body  326  is hollow and defines a chamber (not shown in  FIG. 3 ). A jounce shock charging line  334  extends through a lower wall of the body  326  into the chamber and is connected to a supply of compressed gas, or more preferably a compressed gas/oil mixture.  
         [0030]     The jounce shock assembly  324  also includes a rod  330  that is telescopically disposed in the body  326  and extends from a lower end thereof. The rod  330  has a piston (not shown in  FIG. 3 ) connected to its upper end that seals around the periphery of the chamber while allowing the rod  330  to slide up and down relative to the body  326 . As an alternative, the rod  330  may have a diameter generally matching that of the chamber, with the upper portion of the rod  330 , in effect, forming an integral piston. A piston stop (not shown in  FIG. 3 ) is fixed to the body  326  and located in the chamber to limit the downward travel of the rod  330 . The chamber in the body  326 , along with the piston will trap a compressed gas/oil mixture. The compressed gas/oil mixture will cause the rod  330  to move downward until the piston is seated against the stop.  
         [0031]     The rod  330  also has a blunt-shaped rod cap  332  mounted on a lower free end. The air spring base  302  includes a reaction surface  322  facing the rod cap  332 , preferably with a reaction feature  323  that is shaped to substantially conform to the rod cap  332 . Under normal operating conditions, the piston stop determines the rest position of the piston, with the length of the rod  330  set so that there is a gap between the cap  332  of the rod  330  and the reaction surface  322 . The air spring base  302  includes a plurality of passages  336  formed adjacent to the reaction feature  323 . The passages  336  extend through the reaction surface  322  to an air spring base cavity  338 . The air spring base cavity  338  is in fluid communication with the compressed air cavity  316  through the passages  336  and provides additional compressed air capacity for the assembly  300 . Relative movement between the surfaces  304  and  308  causes relative movement between the air spring base  302  and the top cap  306 . When the base  302  and the cap  306  move towards each other, the air trapped in the compressed air cavity  316  and the air spring base cavity  338  compresses, resulting in a greater resistance to continued relative movement between the base  302  and the top cap  306 .  
         [0032]     Those skilled in the art will appreciate that, as an alternative, the cap  306  of the assembly  300  may be formed with apertures and a top cap cavity (not shown), similar to the air spring base cavity  338  while remaining within the scope of the present invention.  
         [0033]     The operation of the air spring and jounce shock assembly  300  is similar to that of the second embodiment. As the vehicle is driven under normal loading along relatively smooth terrain, the axle assembly  304  and frame  308  will move relative to one another, compressing and decompressing the air in the compressed air cavities  316  and  338 , which support the top cap  306  relative to the base  302 . The jounce shock assembly  324  is sized and positioned so that the rod cap  332  remains spaced from the reaction surface  322  during the normal loading conditions. Accordingly, the air spring and jounce shock assembly  300  acts essentially as a conventional air spring under these driving conditions.  
         [0034]     On the other hand, when the vehicle encounters terrain that causes a large energy input from an impact—such as a pothole or a curb—the air spring diaphragm  310  may allow the axle assembly  304  to drive the base  302  toward the top cap  306  and frame  308  to an extent that the rod cap  332  contacts the reaction surface  322 . Any further movement of the base  302  toward the top cap  306  will now cause the reaction surface  322  to drive the rod  330  into the pressurized chamber. The substantial increase in the effective damping and suspension rate for this air spring and jounce shock assembly  300  over this last portion of travel will prevent the vehicle suspension from bottoming out on the frame. This eliminates the need for separate jounce bumpers (and packaging spaced for them) on the vehicle.  
         [0035]     Referring now to  FIG. 4 , a fourth embodiment of an air spring and jounce shock assembly in accordance with the present invention is indicated generally at  400 . The assembly  400  includes an air spring base  402  that is attached to a vehicle axle assembly (or other suspension component, such as a control arm)  404 . The base  402  is preferably formed of steel, aluminum, a composite material, or the like. The assembly  400  also includes an air spring top cap  406  that is attached to a vehicle frame (or body)  408 . The cap  406  is also preferably formed of steel, aluminum, a composite material, or the like.  
         [0036]     An air spring diaphragm  410  is attached to and seals between the base  402  and the top cap  406 . The diaphragm  410  includes an inner surface  411  that defines a compressed air cavity  416  between the base  402  and the top cap  406 . The diaphragm  410  is preferably formed of an elastomeric material such as rubber or the like, and is attached to the top cap  406  at an upper edge thereof by an upper clamp or spring  412  and to the base  402  by a lower clamp or spring  414  at a lower edge thereof. The top cap  406  includes an air feed line  420  extending therethrough that is connected to a source of compressed air (not shown).  
         [0037]     The air spring base  402  includes a base portion  403  and an integrally formed and upwardly extending support  418  that is also integral with a body  426  of a jounce shock assembly  424 . As defined herein, the term integral means the base portion  403 , the upwardly extending support  418 , and the body  426  are formed as a single piece and are not removable with respect to one another. The jounce shock assembly  424  extends into the cavity  416 . The body  426  is hollow and defines a chamber  427 . A jounce shock charging line  434  extends through a lower wall  429  of the body  426  into the chamber  427  and is connected to a supply of compressed gas, or more preferably a compressed gas/oil mixture.  
         [0038]     The jounce shock assembly  424  also includes a rod  430  that is telescopically disposed in the body  426  and extends from an upper end thereof. The rod  430  has a piston  431  connected to its lower end that seals around the periphery of the chamber  427  while allowing the rod  430  to slide up and down relative to the body  426 . A seal and piston stop  438  is fixed in the body  426  by a threaded flange member  428  and located in the chamber  427  to limit the upward travel of the piston  431 . The seal and piston stop  438  also ensures that the gas/oil mixture in the cavity  427  remains therein. The chamber  427  in the body  426 , along with the piston  431  will trap a compressed gas/oil mixture. The compressed gas/oil mixture will cause the rod  430  to move upward until the piston  431  is seated against the seal and piston stop  438 .  
         [0039]     The rod  430  also has a rod cap  432  with a blunt shape mounted on an upper free end. The top cap  406  includes a reaction surface  422  facing the rod cap  432 , preferably with a reaction feature  423  that is shaped to substantially conform to the rod cap  432 . Under normal operating conditions, the seal and piston stop  438  determines the rest position of the piston  431 , with the length of the rod  430  set so that there is a gap between the cap  432  of the piston  430  and the reaction surface  422 .  
         [0040]     Those skilled in the art will appreciate that the body of the jounce shock assembly of the second and third embodiments may be formed integrally with the air spring top cap assembly, similar to the integral body in this fourth embodiment, while remaining within the scope of the present invention.  
         [0041]     The operation of the air spring and jounce shock assembly  400  is similar to the first embodiment. As the vehicle is driven under normal loading along relatively smooth terrain, the axle assembly  404  and frame  408  will move relative to one another, compressing and decompressing the air in the compressed air cavity  416 , which supports the top cap  406  relative to the base  402 . The jounce shock assembly  424  is sized and positioned so that the rod cap  432  remains spaced from the reaction surface  422  during the normal loading conditions. Accordingly, the air spring and jounce shock assembly  400  acts essentially as a conventional air spring under these driving conditions.  
         [0042]     On the other hand, when the vehicle encounters terrain that causes a large energy input from an impact—such as a pothole or a curb—the air spring diaphragm  410  may allow the axle assembly  404  to drive the base  402  toward the top cap  406  and frame  408  to an extent that the rod cap  432  contacts the reaction surface  422 . Any further movement of the base  402  toward the top cap  406  will now cause the reaction surface  422  to drive the rod  430  into the pressurized chamber  427 . The substantial increase in the effective damping and suspension rate for this air spring and jounce shock assembly  400  over this last portion of travel will prevent the vehicle suspension from bottoming out on the frame. This eliminates the need for separate jounce bumpers (and packaging spaced for them) on the vehicle.  
         [0043]     While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.