Abstract:
An adjustable seat pedestal that allows a user to adjust the height of the seat without sacrificing ride quality. The seat pedestal has a top carrier onto which a seat is mounted and a base that is mounted to the floor of a vehicle. A scissor linkage is employed to allow movement of the carrier toward the base when force is applied through the seat to the carrier when the vehicle hits bumps and forces the user downward. An air bag biases the top carrier upward away from the base. As the upper ends of the scissor linkage move closer together by being pushed upward, a sliding end of the scissor linkage is restrained from movement inward and therefore, limits the maximum height of the pedestal. The pressure in the air bag may be varied which will not change the height above the maximum, but will change the ride quality.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part claiming the benefit of U.S. Utility patent application Ser. No. 12/359,370; filed Jan. 26, 2009, now abandoned the disclosure of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates generally to an air ride seat pedestal for heavy trucks, busses, RVs, and the like that includes a height adjustment that is independent of the air cushioning assembly upon which the seat is supported. 
     Seats for heavy vehicles, including seats that are supported by an air ride assembly, are available in the marketplace. Such air ride assemblies may typically include an air bag or balloon in combination with a piston/cylinder unit connected between the base and the top of the pedestal upon which the seat is mounted. The air bag typically provides cushioning to the seat pedestal and its occupant, while the cylinder unit is geared more toward dampening rebound forces delivered from the ground surface upward through the vehicle&#39;s frame during travel. To adjust the height of the seat requires the inflation or deflation of the air bag. 
     The present systems using an air bag provides inadequate adjustments to accommodate various users of the seat pedestal. To raise the height of a traditional air bag pedestal higher pressure is pumped into the air bag to raise the height. The maximum height that the pedestal may raise to is limited to one maximum position that corresponds to the maximum height the frame around the air bag will rise, or the maximum height is limited by the maximum extension of the air bag. Therefore, maximum height may mean a stiffer ride due to higher pressure in the air bag. This may present a problem for a relatively short individual because he would have to tolerate a softer ride due to the low pressure necessary to lower the seat. Within a traditional seat there is not a way to limit the height of the air bag to a lower height than its maximum height, yet have the air pressure in the air bag corresponding to the maximum height. Thus, in a traditional seat pedestal with an air bag where it is necessary to adjust pressure to lower the height of the pedestal, a short and heavy individual may potentially bottom out the seat pedestal. The ability to selectively lower the maximum height in the seat pedestal, independent of the pressure in the air bag, would provide more flexibility to accommodate various users of the seat pedestal than presently available. 
     SUMMARY OF THE INVENTION 
     The present invention is an adjustable seat pedestal that is used to cushion the ride of an occupant of a vehicle. The pedestal has a top carrier on which a seat is mounted. A base is mounted to the floor of the vehicle. The first linkage, having a lower end and an upper end, is pivotally connected to the base at its lower end. The upper end of the first linkage is slidably connected to the top carrier. A second linkage has a lower end and an upper end. The upper end of the second linkage is pivotally connected to the top carrier and the lower end of the second linkage is pivotally connected to a third linkage. The first and second linkages are connected to each other by a pivotal connection that is located intermediate to the end points of each of the first and second linkages. The third linkage has an upper end that is pivotally connected to the lower end of the second linkage. The lower end of the third linkage is pivotally connected to the base. A stop is retained within the top carrier, located inwardly of the upper end of the first linkage. The stop restricts inward sliding movement of the upper end of the first linkage. A spring biases the top carrier upward and away from the base, and this spring may be an air bag that can be selectively pressurized to change the amount of force biasing the carrier upward. 
     In another aspect of the invention, the stop may be adjustable to change the location at which the upper ends of the first linkage are stopped. This adjustment may be done by having a threaded rod engaging a threaded nut that acts as a stop. The threaded rod may be turned manually or with a motor to facilitate movement of the stop. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view, of the seat pedestal; 
         FIG. 2  is a sectional view taken about line  2 - 2  in  FIG. 1  showing the seat pedestal with the air bag pushing the seat pedestal to its maximum available height and pushing the carriage against the threaded nut stop, which is in its most inward position; 
         FIG. 3  is a close up perspective view of the seat pedestal shown  FIG. 2  in the same position with the air bag pushing carriage against the threaded nut; 
         FIG. 4  is a sectional view showing the same position of the seat pedestal as that shown in  FIG. 3 ; 
         FIG. 5  is a close up perspective view like that of  FIG. 3  with the top carrier moved downward toward the base so the carriage is outward away from the threaded nut; 
         FIG. 6  is a sectional view of the seat pedestal showing the same position as that in  FIG. 5 ; 
         FIG. 7  is a close up perspective with the top carrier moved downward to its lower limit showing the carriage moved further away from the threaded nut than the position shown in  FIGS. 5 and 6 ; 
         FIG. 8  is sectional view showing the same position as that shown in  FIG. 7 ; 
         FIG. 9  is a sectional view showing the threaded nut adjusted to limit the maximum height of the top carrier above the base to a lower height than that shown in  FIGS. 1-8 ; and 
         FIG. 10  is an exploded perspective of the seat pedestal shown in  FIGS. 1-9 . 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The seat pedestal  10  of the present invention is designed to provide a cushioned ride for an occupant of a vehicle in which the pedestal  10  is installed. The pedestal  10  has a base  12  that is made to be fixed to a floor of the vehicle. Typically, this is bolted to the floor of the vehicle. A top carrier  13  is supported above the base  12  with a scissor linkage  16 . The carrier  13  is designed to have a seat affixed to it and this is usually done with bolts so that a user of the pedestal can choose a particular seat. The scissor linkage  16  has a first linkage  18  that has a pair of opposing arms  20  that are the same length. The first linkage  18  has an upper end  22  and a lower end  24 . At the lower end  24  of the first linkage  18 , each arm  20  has a pivotal connection to the base  12 . This connection is done with a bolt  26  held in a clevis  28  on the rearward end of the base  12 , as shown in  FIGS. 1 and 10 . The upper end  22  of the first linkage  18  has sliding blocks  30  that are pivotally attached to the upper ends  22  of each arm  20 . The arms  20  are joined together with a cross member  32 . The sliding blocks  30  are T-shaped and are adapted for riding in a C-channel  31 . 
     A second linkage  36  of the scissor linkage  16  has an upper end  38  and a lower end  44 . The upper end  38  is pivotally connected to the carrier  13  with bolt  39 . The lower end  44  is pivotally connected to a third linkage  43 . Between the upper end  38  and lower end  44  of the second linkage  36 , it is pivotally connected to the first linkage  18 . The second linkage  36  pivots about apertures  46  when it is connected to the first linkage  18 . Bolt  48  pivotally connects the first and second linkages  18 ,  36 . Apertures  46  are located on opposite sides of the second linkage  42  and each receive a bolt  48 . The third linkage  43  has its upper end  50  pivotally connected to the lower end  44  of the second linkage  36 . A lower end  54  of the third linkage is pivotally connected to a forward end of the base  12 . 
     A carriage  58  is pivotally connected to the first linkage  18  and spans across to each upper end  22  of each arm  20 . The carriage  58  is connected inside the arms  20 , opposite the sliding blocks  30 . The carriage  58  has guide holes  60  that are adapted for receiving guide rods  62  that are affixed to a forward flange  66  of the top carrier  13 . A central hole  68  has an inner diameter that is larger than a threaded rod  70  that passes through the carriage  58 . The carriage  58  moves as the first linkage  18  moves relative to the top carrier  13 . This movement occurs when the top carrier  13  moves nearer or farther from the base  12 . The threaded rod  70  is longitudinally fixed to the forward flange  66  and is rotatable within the flange  66 . 
     The treaded threaded rod  70  is connected to a threaded nut  72  that acts as a stop. The threaded nut  72  limits the inward travel of the carriage  58 , and thus limits the inward movement of the upper ends  22  of the arms, and sliding blocks  30 . A knob  80  attached to the threaded rod  70  may be used to rotate the rod  70  and move the location of the threaded nut  72 . As shown in  FIG. 3 , the upper ends  22 , and carriage  58  are in their most inwardly available position due to being stopped by the nut  72 . A rubber washer  82  is located adjacent to nut  72  to prevent metal to metal contact as the carriage  58  is stopped by the nut  72 . Rotating the knob  80  moves the nut  72  and changes the maximum inward position of the upper ends  22 . The nut  72  has bolts  86  extending upward from it that ride in slots  88  in the carrier  13 . Plastic washers  90  on the bolts  86  provide a low friction connection to the carrier  13  so the nut  72  may slide relatively easily relative to the carrier  13  when the adjustment knob  80  is turned. 
     An air bag  92  acts as a spring urging the carrier  13  away from the base  12 . The bag  92  is attached to the cross member  32  and to the carrier  13 . The air bag  92  extends through an aperture  93  in the second linkage  36 . The bag  92  may be selectively filled to a desired pressure that will correspond to a larger force urging the carrier upward with higher pressure, and a lower force urging the carrier upward with lower pressure. A gas spring  94  may be added to urge the second  36  linkage upward, and therefore urge the carrier upward. The gas spring  94  will provide a more constant force over its change in length than either an air bag  92  or a conventional coil spring. Its position is shown in  FIG. 10 , but it is not necessary to have the gas spring  94  because the air bag  92  can provide sufficient force to support the carrier  13  and an occupant seated on a seat mounted to the carrier  13 . A damper  98  is connected to the first linkage  18  to provide damping of movement during travel of the vehicle. Excessive movement would cause irritating bouncing for a user of the seat attached to the pedestal  10 . 
     Weight or force exerted upon the carrier  13  through a seat that is attached to it will cause movement within the scissor linkage  16  in a controlled manner. Force exerted downwardly on the carrier will move the upper ends  22  of the first linkage  18  away from the upper ends  38  of the second linkage  36 . This will cause the carriage  58  to slide smoothly along its guide rods  62  as well as cause the slide blocks  30  to slide within their respective C-channels  31 . Downward movement of the carrier  13  toward the base  12  will also cause the lower ends  44 ,  24  of the second linkage  36  and first linkage  18  respectively to move apart. Since the lower end  24  of the first linkage  18  is pivotally attached to the base  12  it cannot move laterally, it is the lower end  44  of the second linkage  36  that pivotally moves with the upper end  50  of the third linkage  43  to facilitate lateral movement. It is this accurate movement that allows the lower ends  44 ,  24  to move apart laterally as necessary to facilitate near parallel movement of the carrier  13  relative to the base  12 . During this movement the nut  72  remains in its position and it is the carriage  58  that moves away from the nut  72 . The guide rods  62  and slide blocks  30  provide a complementary guidance to the upper ends  22  so that binding does not occur due to parts camming into each other. The fact that all of the other connections in the scissor linkage  16  other than slide blocks  30  are pivotal allows the forward most edge  63  of the base to be located rearward of where it otherwise would be if sliding connections were used at both forward most connections on the carrier  13  and base  12 . 
       FIG. 3  shows the carrier  13  at its maximum height above the base  12 . This corresponds the bolts  86  being moved to their maximum inward positions within the slots  88 . The carriage rests against the rubber washer  82  which is stopped against the threaded nut  72 .  FIG. 4  is a sectional view of this same position. In the position shown in  FIGS. 3 and 4 , the air bag  92  has fully biased the carrier  13  upward.  FIGS. 5 and 6  illustrate what will happen when force is put on the carrier  13  that is sufficient to overcome the biasing force of the air bag  92 . This force can come from the weight of the occupant or could be the intermittent force from the occupant resulting from the vehicle hitting a bump. The carriage  58  is connected to the upper ends and will move outward with the upper ends  22  and away from the threaded nut  72  when the carrier  13  is forced downward. The carriage  58  may be forced downward until it reaches the forward flange  66 , which stops further outward movement and defines the lowest possible height the carrier  13  will be above the base  12 .  FIGS. 7 and 8  show the lowest possible height of the pedestal. The difference between the height of the carrier  13  in  FIGS. 3 ,  4  and FIGS.  7 , 8  is the maximum travel of the seat pedestal.  FIG. 9  shows threaded nut  72  being adjusted outwardly or more near the forward flange  66  than in  FIGS. 3-8 . This limits the maximum height that the carrier  13  may be above the base  12  to a lower height than that of  FIGS. 3-8 . Downward force on the carrier  13  will move the carriage  58  away from the threaded nut  72  in the same fashion as that which occurs in  FIGS. 3-8 , but the overall range will be less than that of  FIGS. 3-8 . 
     In use, the pedestal  10  offers a great amount of adjustability to choose desired ride characteristics without changing the pedestal  10  itself. The full height of the carrier  13  above the base, or the seat height is determined by adjusting the adjustment knob  80  to move the nut  72 . This adjustment may be manually done through the use of a knob  80 , or could potentially be done by the use of a motor.  FIGS. 3 and 4  show the seat at full height with no weight upon the seat. This position could also be the position in which too little weight is put upon the seat and carrier  13  to push the carrier  13  downward. In this configuration, the air bag  92  pushes upwardly on the carrier  13  and thus moves the sliding upper ends  22  of arms  20  inward toward the center of the carrier  13 . The ends  22  are connected to the carriage  58  so the carriage  58  moves inwardly with the ends  22  and the nut  72  limits the inward movement of the carriage  58 . The nut  72  will prevent inward movement of the carriage  58  no matter what pressure is put into the air bag  92 . If a vehicle occupant wishes to have a hard ride in which it would take a great deal of force to push the seat and carrier  13  downward, more air pressure will be put into the bag  92 .  FIGS. 5 and 6  correspond to a position where enough weight or force has been placed upon the carrier  13  so that the carrier  13  has been forced downward toward the base  12 . As can be seen in  FIGS. 5 and 6 , the nut  72  is located in the same position relative to the forward flange  66  as it was in  FIGS. 3 and 4 , but the carriage  58  has moved outward relative to the nut  72 . This movement will occur when the vehicle hits a bump and the carrier  13  moves to cushion the occupant. The maximum amount the carrier  13  can move downward is until the carriage  58  is stopped against the forward flange  66 , and this may never happen if the air bag  92  is pumped with air of sufficient pressure. If the air bag  92  is pumped with a great amount of pressure, the force required to move the carrier  13  downward and the carriage  58  outward may be so high that under ordinary circumstances during vehicle travel, the carrier  13  and seat attached to it do not move downward. This would correspond to an extremely hard ride setting. 
     The pedestal  10  of the present invention allows adjustment not possible with just an air bag. In the prior art, simply using an air bag for more height required more air pressure. Lower height required less air pressure. This would mean a shorter vehicle occupant, who would use a traditional seat, would have to tolerate a softer ride because the low pressure in the air bag would provide that. In the case of the present invention, a shorter occupant who would like a harder ride could adjust the nut  72  into a position corresponding to a relatively near distance to the forward flange  66  and then he could pressurize the air bag  92  to a high level of pressure for a firm ride at low height. This could also be a benefit to a shorter heavier user of the seat because with the present invention the higher pressure in the air bag  92  could prevent bottoming out. In the past, high pressure might put the pedals out of reach for a shorter individual. As such, the present invention makes it possible to accommodate different weight and sized people to an extent that was not possible before without having to change out the seat pedestal  10  itself. 
     The present invention is not limited to the details given above, but may be modified within the scope of the following claims.