Abstract:
A suspension damper assembly capable of adjusting the height of an automobile includes a cylinder tube defining a pumping chamber aligned concentrically within a reservoir tube. A fluid reservoir is defined between the reservoir tube and the cylinder tube. A piston is slideably disposed within the cylinder tube. A gas cup is slideably disposed within the assembly and separates a fluid chamber within the cylinder tube from a gas chamber. The gas cup includes a cup conduit connecting the pumping chamber to the reservoir chamber whereby stroking the gas cup pumps fluid into the pumping chamber increasing the outward force of the piston for raising the height of the vehicle. A piston shaft guide includes a shaft valve allowing fluid to pass from the pumping chamber to the reservoir chamber for reducing the outward force of the piston and lowering the height of the vehicle.

Description:
TECHNICAL FIELD 
     The present invention relates generally to an improved suspension damper for a motor vehicle. More specifically, the present invention relates to a suspension damper capable of adjusting the height of the motor vehicle. 
     BACKGROUND OF THE INVENTION 
     Suspension dampers are typically attached to a spring assembly of a vehicle suspension system to dampen vibrations derived from such variables as rough road surfaces, pot holes, and unbalanced tires. The spring force generally determines the height of the vehicle and the damper controls the dynamic vehicle motion. Often, it is desirable to supplement the spring force to maintain a controlled vehicle height at different levels of vehicle load. One method of doing so is to affix a height leveling damper to the suspension system that adjusts the height of the vehicle relative to the load on the vehicle. 
     Presently, to maintain the controlled vehicle height, the spring force is supplemented with an air leveling damper that requires an external compressor and controller. An air sleeve is attached to the outside of the air leveling damper to supply an extending force to the damper for maintaining the controlled vehicle height. This type of damper adds a significant amount of mass to the vehicle due to the addition of the compressor and the controller. Further, the controller associated with the air leveling damper requires sensors and related electronics to adjust the height of the vehicle. 
     Therefore, it would be desirable to utilize a self leveling damper with the vehicle suspension system that does not require additional external components such as an air compressor and a controller. 
     SUMMARY OF THE INVENTION 
     The present invention is a suspension damper assembly capable of adjusting the height of an automobile. A cylinder tube defining a pumping chamber is aligned concentrically within a reservoir tube. A fluid reservoir is formed between the reservoir tube and the cylinder tube. A piston has a plunger slideably disposed within the cylinder tube. The plunger is affixed to a piston shaft inserted through a first end of the reservoir tube. The shaft is inserted through a shaft guide that seals the pumping chamber from the fluid reservoir at the first end. 
     A gas cup is slideably disposed within the assembly forming a fluid chamber within the cylinder tube with the shaft guide. The gas cup also forms a gas chamber with a second end of the cylinder tube. The gas cup includes a cup conduit connecting the pumping chamber to the reservoir chamber. When the gas cup pumps fluid into the pumping chamber, fluid pressure inside the pumping chamber is increased providing a force that telescopes the shaft outwardly of the cylinder tube thereby raising the height of the vehicle. 
     The shaft is inserted through a spring that biases the plunger away from the shaft guide retracting the shaft into the cylinder tube. The shaft guide includes a shaft conduit connecting the fluid chamber to the reservoir. The shaft conduit is sealed with a shaft valve wherein compression of the spring opens the shaft valve allowing fluid to pass from the pumping chamber to the reservoir chamber thereby reducing the outward force of the piston and lowering the height of the vehicle. 
     The suspension damper of the present invention adjusts the height of the vehicle using mechanisms completely concealed within the damper. The damping action of the piston transfers fluid throughout the damper to adjust the height of the vehicle according to the load on the vehicle. Unlike height adjusting dampers presently available, external compressor or electronic controllers are not required. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
     FIG. 1 is a plan view of the damper assembly of the subject invention; 
     FIG. 2 is partial sectional view along line  2 — 2  of FIG. 1 showing the gas cup, 
     FIG. 2 a  is a partial sectional view along line  2 — 2  of FIG. 1 showing an alternate section of the gas cup; 
     FIG. 3 is a partial sectional view along line  3 — 3  of FIG. 1 showing the piston assembly; 
     FIG. 4 is an exploded view of the damper assembly of the subject invention; 
     FIG. 5 is an exploded view of the piston assembly; 
     FIG. 6 is a partial section view of the valve seat showing the cavity passage and the vent passage having the valve plate closed; 
     FIG. 7 is a partial section view of the valve seat showing the cavity passage and the vent passage having the valve plate opened; 
     FIG. 8 is a partial sectional view of the gas cup; and 
     FIG. 9 is an exploded view of the gas cup and the cylinder end assembly. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 3, a suspension damper assembly capable of adjusting the height of an automobile is generally shown at  10 . A reservoir tube  12  forms a housing and has a cylinder tube  14  concentrically aligned within the reservoir tube  12 . The cylinder tube  14  defines a pumping chamber  13 . A fluid reservoir  16  is defined between the reservoir tube  12  and the cylinder tube  14 . As shown in FIGS. 2 and 2 a , a gas cup  18  is slideably disposed within the cylinder tube  14 . The gas cup  18  and a cup conduit  20  are located in the pumping chamber  13  with the fluid reservoir  16 , the purpose of which will be explained further below. A cylinder end assembly  21  encloses the end of the pumping chamber  13  and forms a gas chamber  19  with the gas cup  18 . 
     Referring to FIGS. 3 and 4, a piston assembly  22  includes a plunger  23  slideably disposed within the cylinder tube  14 . The plunger  23  is affixed to a piston shaft  24  that is inserted through a tube adapter  26  disposed upon an end of the reservoir tube  12  opposite the gas cup  18 . The tube adapter  26  includes a fluid relief tube  28 , the purpose of which will be explained further below. An end cover  30  is threaded onto the reservoir tube  12  and retains the tube adapter  26  to enclose the end of the reservoir tube  12 . An end cover seal  32  seals the end cover  30  to the reservoir tube  12  thereby preventing fluid from leaking from the assembly  10 . The end cover  30  includes an end cover aperture  34  that receives the piston shaft  24 . The piston shaft  24  includes a fastening element  36  that affixes the assembly  10  to a suspension frame (not shown). 
     A base cap  38  encloses the opposite end of the reservoir tube  12  and receives the cylinder end assembly  21  as shown in FIGS. 1,  2 , and  2   a . The base cap  38  is sealed to the cylinder end assembly  21  with a base seal  40 . The base cap  38  includes a base fastening element  42  to affix the assembly  10  to the suspension system of the vehicle. The base cap  38  includes a fluid fill aperture  44  for filling the fluid reservoir  16  with fluid. A fluid fill plug  46  seals the fluid fill aperture  44 . The base cap  38  further includes a gas fill aperture  48  that connects to the gas chamber  19  for filling the gas chamber  19 . A gas check valve  50  is disposed within the gas fill aperture  48  for preventing gas from exiting the gas chamber  19  during filling. A gas cap  51  seals the gas fill aperture  48 . 
     The novel features of the piston assembly  10  are best shown in FIGS. 3,  6  and  7 . The plunger  23  includes a plurality of passages  54  that allow the fluid to flow therethrough while the plunger  23  strokes inside the pumping chamber  13  as is well known in the art of suspension dampers. The passages  54  are designed to restrict, but not prevent the flow of fluid. A plunger plate  56  blocks the passages  54 , but flexes under the force of the fluid to open the passages  54  for allowing the fluid to flow through. 
     The piston shaft  24  is inserted through a spring  58  that is aligned on the piston shaft  24  with a spring bearing  60 . The spring  58  is disposed between the spring bearing  60  and the plunger  23 . The spring bearing  60  includes a spring rim  62  that prevents the spring  58  from sliding off of the spring bearing  60 . A valve lifter  64  includes a lifter rim  66  that abuts the spring rim  62 . A valve seat  68  includes a valve seat cavity  70  (FIG. 5) for receiving both the valve lifter  64  and the spring bearing  60 . A seal plate  72  is disposed between the valve seat  68  and a shaft washer  74 . The shaft washer  74  includes a recess  76 , which has a diameter smaller than the diameter of the seal plate  72 . The valve seat  68  and the shaft washer  74  are inserted into the cylinder tube  14  along with the piston shaft  24  and the plunger  23 . A pair of valve seat seals  78  seal the valve seat  68  to the cylinder tube  14 . A shaft bearing  80  aligns the piston shaft  24  within the shaft washer  74 . A shaft seal  82  is received by the shaft washer  74  thereby sealing the piston shaft  24  to the shaft washer  74  to prevent fluid from leaking from the assembly  10 . 
     As best shown in FIGS. 6 and 7, the valve seat cavity  70  includes a plurality of cavity passages  84 , and a plurality of vent passages  86 , which are aligned outside of and concentrically with the cavity passages  84 . The cavity passages  84  lead to the pumping chamber  13  and the vent passages  86  lead to the fluid reservoir  16 . The cavity passages  84  and the vent passages  86  are both sealed by the seal plate  72 . 
     The valve lifter  64  abuts the seal plate  72 . As will be described further below, pressure in the pumping chamber  13  can increase during operation of the vehicle. As pressure increases, the plunger  23  exerts force on the spring  58  transferring force to the spring bearing  60  and to the valve lifter  64 . The increased force will cause the valve lifter  64  to flex the seal plate  72  into the recess  76  disposed upon the shaft washer  74  causing the cavity passage  84  to be unsealed, which allows fluid to flow out of the pumping chamber  13 . The flexed seal plate  72  also unseals the vent passage  86  allowing fluid to flow from the cavity passage  84  into the vent passage  86  and into the fluid reservoir  16  where the fluid pressure is lower than in the pumping chamber  13 . 
     Referring again to FIGS. 2 and 2 a , the cylinder end assembly  21  includes a central cylinder end aperture  88  that receives the cup conduit  20 . The cylinder end aperture  88  communicates with the fluid reservoir  16  through a cylinder end connection tube  90  (FIG. 2 a ). A conduit seal  92  seals the cup conduit  20  to the cylinder end assembly  21 . A seal retainer  94  and a retainer ring  96  secure the conduit seal  90  to the cup conduit  20 . The conduit seal  92  prevents fluid from leaking from the central cylinder end aperture  88  into the gas chamber  19 . 
     A commercial check valve  98  is inserted into the cylinder end connection tube  90  for preventing fluid from leaving the cylinder end aperture  88  and entering the fluid reservoir  16 . The cylinder end assembly  21  further includes a pressure relief valve  100  that would allow the emergency pressure release if the fluid pressure in the cylinder end aperture reaches a critical level. 
     The base cup  38  encloses the assembly  10  and receives the cylinder end assembly  21 . The central cylinder end aperture  88  communicates with the fluid fill aperture  44  disposed within the base cup  38 . A base seal  108  seals the base cup  38  to the reservoir tube  12 . 
     A first cylinder base seal  110  seals the cylinder end aperture  88  to the base cup  38  for preventing fluid from leaking from the cylinder end aperture  88 . A second cylinder base seal  112  separately seals the cylinder end assembly  21  to the base cup  38 . A cylinder seal  114  seals the cylinder end assembly  21  to the cylinder tube  14 . 
     As best shown in FIGS. 8 and 9, the gas cup  18  includes a check valve  116  that allows fluid to flow into the pumping chamber  13  from the fluid reservoir  16  though the cup conduit  20 . The check valve  116  includes a ball  118  that is forced against the cup conduit  20  by a ball spring  120 . The force of fluid passing through the cup conduit  20  from the fluid reservoir  16  when the gas cup  18  is stroking forces the ball away from the conduit  20 . The ball spring  120  forces the ball  118  against the cup conduit  20  when the force of fluid disposed within the pumping chamber  13  is not able to overcome the force of the ball spring  120 . A travel limiter  122  abuts the ball spring  120  for preventing the ball  118  from passing through the ball spring  120 . A retention ring  124  retains the ball  118 , the ball spring  120 , and the travel limiter  122  to the gas cup  18 . The gas cup  18  includes a cup seal  126  (FIGS. 2,  2   a ) that encircles the gas cup  18  sealing the gas cup  18  to the cylinder tube  14 . The cup seal  126  prevents gas from leaving the gas chamber  19  and entering the pumping chamber  13 . The cup seal  126  also prevents fluid from leaving the pumping chamber  13  and entering the gas chamber  19 . The cylinder end assembly  21  includes a passage  128  that communicates with the gas fill aperture  48  for filling the gas chamber  19  with gas. 
     A gas bag  130  is disposed within the fluid reservoir  16  as is known in the art of suspension damper assemblies. The relief fluid tube  28  is positioned within the fluid reservoir  16  adjacent to gas bag  130 . The relief fluid tube  28  receives fluid from the vent passage  86  to return fluid to the fluid reservoir  16  from the pumping chamber  13  when the seal plate  72  has been flexed by the valve lifter  64 . 
     During operation, the piston assembly  22  will stroke inside the pumping chamber  13  when vibrations are received from the suspension system from such variables as, for example, pot holes, rough road surfaces and unbalanced tires. The stroking action will transfer fluid pressure to the gas cup  18  causing the gas cup  18  to compress the gas chamber  19 . Therefore, the gas cup  18  derives stroking action from the piston assembly  22 . The stroking action of the gas cup  18  pumps fluid from the cylinder end aperture  88  into the pumping chamber  13 . As the fluid in the cylinder end aperture  88  is depleted, a pressure drop is created in the cylinder end aperture  88  drawing fluid from the fluid reservoir  16  into the cylinder end aperture  88 . 
     As fluid pressure builds in the pumping chamber  13  from the combination of additional fluid and compressed gas in the gas chamber  19 , the piston assembly  22  compresses the spring  58  causing the piston shaft  24  to telescope out of the assembly  10  automatically raising the height of the vehicle. As the amount of fluid increases in the pumping chamber  13 , pressure is exerted upon the gas cup  18 , which in turn decreases the volume of gas chamber  19 . As a result, the gas pressure in the gas chamber  19  is increased, which increases the fluid pressure in the pumping chamber  13 . The increased fluid pressure in the pumping chamber  19  increases the force of the piston shaft  24 , which will telescope the shaft  24  out of the tube  28  thereby raising the level of the vehicle. 
     The compression force of the spring  58  by the telescoped piston shaft  24  will cause the valve lifter  64  to flex the seal plate  72  allowing fluid to exit the pumping chamber  13  through the cavity passage  84  and enter the vent passage  86  returning to the fluid reservoir  16 . As fluid is evacuated from the pumping chamber  13 , the pressure inside the pumping chamber  13  will decrease allowing the spring  58  to retract the piston shaft  20  into the assembly automatically lowering the height of the vehicle. This process of filling and evacuating the pumping chamber  13  with fluid occurs with each stroke of the piston assembly  22 . As is readily apparent, the height of the vehicle is determined by the compression force of the spring  58 . A spring  58  having a high compression force will more readily cause a valve lifter  64  to flex the seal plate  72  thereby maintaining the vehicle at a lower height. A spring  58  having a lower compression force will less readily cause the valve lifter  64  to flex the seal plate  72 , leaving the piston shaft  24  in a telescoped orientation, maintaining the vehicle at a greater height. 
     The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, wherein reference numerals are merely for convenience and are not to be in any way limiting, the invention may be practiced otherwise than as specifically described.