Abstract:
A suspension system for an “All Belts To Seat” or “ABTS” style seat is provided that includes a floor bracket, seat bracket, and an equalizing bracket. Means for allowing motion between the seat bracket and floor bracket is provided by a set of cams. The equalizing bracket connects the cams and ensures synchronized rotation. The height of the seat bracket is adjustable with respect to the floor bracket by means of an air spring, and motion between the two brackets is dampened by an interconnected shock absorber.

Description:
BACKGROUND 
   The present invention relates to a seat having a suspension system. 
   SUMMARY 
   In one embodiment, the invention provides a seat adapted to be mounted to the floor of a vehicle. The seat includes an operator-occupied portion comprising base and upright portions to support an operator seated in the seat. The seat also includes a seat belt system including a belt reel mounted to one of the upright and base portions of the seat, a belt having one end interconnected with the belt reel to facilitate winding the belt onto the belt reel and an opposite end affixed to one of the upright and base portions of the seat, a first buckle member interconnected with the belt, and a second buckle member affixed to one of the upright and base portions of the seat, wherein interconnecting the first and second buckle members causes portions of the belt to extend across the lap and chest of a person sitting in the seat. A suspension system supports the operator-occupied portion of the seat and dampens up and down movement of the operator-occupied portion of the seat with respect to the vehicle floor. 
   In another embodiment, the invention provides a seat adapted to be mounted to the floor of a vehicle. The seat includes an operator-occupied portion comprising base and upright portions to support an operator seated in the seat. The seat also includes a suspension system including a frame mounted to the vehicle floor and supporting the operator occupied portion of the seat, and at least one suspension rod having a longitudinal axis and supported at first and second ends by the frame. The at least one suspension rod contains a circumferential groove near the second end, a means for resisting rotation of the suspension rod with respect to the portion of the frame supporting the suspension rod, and a locking member having an aperture sized to fit over the second end of the suspension rod and into the circumferential groove to resist motion of suspension rod in a direction parallel to the longitudinal axis. 
   In another embodiment the invention provides a suspension system for a seat adapted to be mounted to the floor of a vehicle. The suspension system includes a seat frame adapted to be mounted to the bottom of the seat and a floor frame adapted to be mounted to the vehicle floor. The invention also provides a forward suspension rod and a rear suspension rod, both interconnected at opposite ends to the floor frame and oriented generally parallel to each other, and a forward seat rod and a rear seat rod, both interconnected at opposite ends to the seat frame and oriented generally parallel to each other and generally parallel to the forward and rear suspension rods. The invention further provides a pair of forward cams, each of said forward cams being rotatably mounted to both the forward suspension rod and the forward seat rod, and a pair of rear cams rotatably mounted to each of the rear suspension rod and rear seat rod. The invention further provides an equalizing bracket interconnected to at least one of forward cams and to at least one of the rear cams. The invention further provides a biasing member applying a biasing force between the seat frame and floor frame, biasing the seat frame toward a default position with respect to the floor frame, and a shock absorber dampening movement of the seat frame with respect to the floor frame. Movement of the seat frame from the default position against the biasing force of the biasing member causes rotation of the forward and rear cams, wherein the interconnection of the equalizing bracket to the forward and rear cams synchronizes rotation of the forward and rear cams. 
   Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front perspective view of a seat embodying the invention. 
       FIG. 2  is a rear perspective view of the seat. 
       FIG. 3  is a cross-sectional view taken along line  3 — 3  in  FIG. 1 . 
       FIG. 4  is an exploded view of the suspension system of the seat. 
       FIG. 5  is a side view of the suspension system of the seat in a first operating position. 
       FIG. 6  is a side view of the suspension system of the seat in a second operating position. 
       FIG. 7  is a side view of the suspension system of the seat in a third operating position. 
   

   DETAILED DESCRIPTION 
   Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     FIG. 1  illustrates a seat  10  having first and second sides  12 ,  13  (also referred to as left and right sides, respectively). The seat  10  includes a base portion  15  and an upright portion  20  that extends up from and is pivotable with respect to the base portion  15 . The base and upright portions  15 ,  20  (together referred to herein as the “operator-occupied” portion of the seat) are supported by a suspension and shock absorbing apparatus  25  that provides a smooth ride for an operator seated in the seat  10 . 
   With reference to  FIGS. 1–3 , the base portion  15  of the seat  10  includes a rigid base frame  30  and a bottom cushion  35  for supporting an operator seated in the seat  10 . With reference particularly to  FIG. 3 , the upright portion  20  includes a rigid back frame  40  and a seat back cushion  45  mounted to the back frame  40 . The upright portion  20  of the seat  10  is pivotably mounted to the base portion  15  about a pivot axis  47  ( FIGS. 2 and 4 ). The orientation of the upright portion  20  of the seat  10  with respect to the base portion  15  is characterized by the included angle α ( FIG. 3 ) between the top of the bottom cushion  35  and the front of the seat back cushion  45 . 
   The recline and bottom cushion height adjustment mechanisms are actuated through respective recline and cushion levers  50 ,  53  ( FIG. 2 ) on the right side  13  of the seat. The recline and bottom cushion height adjustment mechanisms are described and illustrated in more detail in co-pending and commonly-assigned U.S. patent application Ser. No. 11/175,659, titled “Seat Having Cushion Height and Recline Adjustment Mechanisms” and filed on Jul. 6, 2005, the entire contents of which are incorporated herein by reference. The illustrated seat  10  is useful, for example, as the driver&#39;s seat in a bus or delivery vehicle having no door on the driver&#39;s side. In such vehicles, the driver&#39;s seat is often positioned very close to a wall on the left side  12 , and there is little clearance for the operator&#39;s hand to reach between the wall and seat on the left side  12 . Positioning the recline actuation lever  50  and the cushion actuation lever  53  on the right side  13  affords easier access by the operator than if they were on the left side  12 . The illustrated seat  10  can be used in other applications, however, whether or not there is a driver&#39;s side door. 
   The illustrated seat  10  is of the type commonly referred to in the art as an “All Belts To Seat” or “ABTS” seat. ABTS seats include seat belt arrangements with all anchor points on the seat frame itself, rather than on any structural portion of the vehicle in which the seat is mounted. ABTS seats are therefore modular in the sense that they can be installed in a vehicle without separate installation considerations for the seat belt. In the United States, Federal Standards FMVSS 207 &amp; 210 dictate the forward force that a seat must withstand through its seat belt (referred to in the art as the “pull test”). To pass the pull test, most ABTS seats require a tether interconnecting the seat and the vehicle in addition to the seat&#39;s standard floor mounting. 
   The illustrated seat  10  includes a seat belt arrangement comprising a belt reel  55  ( FIG. 3 ) mounted to the back frame  40  on the first side  12  of the seat  10 , a belt  65  having one end interconnected with the belt reel  55  to facilitate winding the belt  65  onto the belt reel  55  and an opposite end affixed to the base frame  30  at a first anchor point  70  on the first side  12  of the seat, a first buckle member  75  interconnected with the belt  65 , and a second buckle member  80  ( FIG. 2 ) affixed to the base frame  30  at a second anchor point  83  on the second side  13  of the seat  10 . In this regard, both of the opposite ends of the belt  65  are mounted to the seat frame  30 ,  40  and not to the vehicle in which the seat  10  is installed. The belt  65  extends up from the belt reel  55  along the back frame  40  to a height even with or slightly above the shoulder height of an operator seated in the seat  10 . The belt  65  then extends down to the first anchor point  70 . Interconnecting the first and second buckle members  75 ,  80  causes portions of the belt  65  to extend across the lap and chest of the operator sitting in the seat  10 . The first buckle member  75  slides along the belt  65  to accommodate the size of the operator. 
     FIG. 4  illustrates the components of the suspension system  25 , including a floor bracket  85 , a seat bracket  90 , and an equalizing bracket  95 . The floor bracket  85  is rigidly affixed to the floor of the vehicle in which the seat  10  is installed. The operator-occupied portion of the seat  10  is mounted on top of the seat bracket  90 . More specifically, the base frame  30  is mounted to the seat bracket  90 . The suspension system  25  also includes a plurality of suspension support rods  100 , each having a circumferential groove  103  at one end and a longitudinal axis  105 . A flange  110  is fixed (i.e., welded or otherwise rigidly affixed) to the end of each support rod  100  opposite the circumferential groove  103 , and a locking member  140  is mounted in the circumferential groove  103 . More specifically, the locking member  140  has an aperture with a large diameter portion sized to fit over the end of the support rod  100  and a small diameter portion sized to snugly fit into the circumferential groove  103 . The suspension system  25  also includes a plurality of tubes  115 , a plurality of suspension cams  120 , an air spring  125 , a shock absorber  130 , and a pair of shock cams  135 . 
   The tubes  115  define bores having a diameter slightly larger than the diameter of the suspension support rods  100 . The suspension support rods  100  fit snugly within the tubes  115  such that the longitudinal axis of each bore is substantially aligned with the longitudinal axis  105  of the associated rod  100 . The rods  100  and tubes  115  are free to rotate with respect to each other, and in this regard the rods  100  may be characterized as being journaled within the tubes  115  or the tubes  115  may be characterized as being journaled on the rods  100 . Nylon (or any other suitable low-friction material) bushings  118  may be employed between the suspension rods  100  and the suspension tubes  115  to reduce friction and noise, and to ensure a snug fit. Each suspension cam  120  defines three holes, two of which are of a diameter slightly larger than the outer diameter of the tubes  115 , and one of which has a diameter slightly larger than the diameter of the suspension support rods  100 . 
   The suspension support rods  100 , cams  120 , and tubes  115  are divided into substantially identical forward and rear sets. Within each set, a first one of the suspension support rods  100  extends through and is supported by holes at opposite sides  12 ,  13  of the floor bracket  85 . The flange  110  and locking member  140  for this first suspension support rod  100  are fastened to the floor bracket  85  to prevent rotation and movement along the longitudinal axis  105  of the first suspension support rod  100  with respect to the floor bracket  85 . A first one of the tubes  115  is journaled on this first suspension support rod  100  between the sides of the floor bracket  85 . The suspension cams  120  receive the first tube  115  within one of their larger-diameter holes and are positioned at the opposite ends of the first tube  115 . 
   Within each of the forward and rear sets, a second one of the suspension support rods  100  extends through and is supported by holes at opposite sides  12 ,  13  of the seat bracket  90 . The flange  110  and locking member  140  for this second suspension support rod  100  are fastened to the seat bracket  90  to prevent rotation and movement along the longitudinal axis  105  of the second suspension support rod  100  with respect to the seat bracket  90 . A second one of the tubes  115  is journaled on this second suspension support rod  100  between the sides of the seat bracket  90 . The suspension cams  120  receive the second tube  115  within the other larger-diameter hole and are positioned at the opposite ends of the second tube  115 . 
   Also within each of the forward and rear sets, a third one of the suspension support rods  100  is journaled within an integral tube  115  within the equalizing bracket  95 . The suspension cams  120  receive either end of the third suspension support rod  100  within the smaller diameter hole. The flange  110  and locking member  140  for this third suspension support rod  100  are fastened to the associated suspension cam  120  to prevent rotation and movement along the longitudinal axis  105  of the third suspension support rod  100  with respect to the suspension cam  120 . 
   The equalizing bracket  95  is interconnected to the suspension cams  120  and the suspension support rods  100  in order to increase stiffness between interconnecting parts in the suspension system  25  and to synchronize the motion of the forward and rear suspension cams  120 . Synchronization of the suspension cam  120  motion ensures the operator-occupied portion of the seat  10  does not tilt front to back. At the upper and lower limits of the suspension system&#39;s  25  range of motion, the equalizing bracket  95  contacts range of motion limiters  137  ( FIGS. 5–7 ) on the floor bracket  85 . This contact limits the range of motion of the suspension system  25  and prevents damage to the suspension system  25  due to excessive suspension travel. In other embodiments the equalizing bracket  95  may be eliminated if acceptable suspension system  25  stiffness, synchronization of the cams  120 , and range of motion limitations can be achieved without it. 
   Each shock cam  135  includes first and second holes of diameter slightly larger than the outer diameter of the tubes  115 , and a third hole sized for a fastener that is journaled within one end of the shock absorber  130 . In the illustrated embodiment, the first and second tubes  115  of the front set extend through the first and second larger-diameter holes in the shock cam  135 , and the opposite end of the shock absorber  130  is pivotably mounted to the seat bracket  90 . 
   One end of the air spring  125  is mounted to the floor bracket  85  and the other end is mounted to the seat bracket  90 . The air spring  125  is centered with respect to the floor bracket  85  and seat bracket  90  and extends through a window  145  in the equalizing bracket  95 . The window  145  is sized such that the equalizing bracket  95  does not come into contact with the air spring  125  as the equalizing bracket  95  moves through its full range of motion. The air spring  125  is vertically-oriented and biases the seat bracket  90  up away from the floor bracket  85 . In an alternative embodiment, the air spring  125  may be replaced with a coil spring  125 ′, see  FIG. 3 , or other suitable biasing means. One advantage to using an air spring rather than a coil spring lies in the ability to connect the air spring to the vehicle&#39;s pneumatic system and change the air spring&#39;s stiffness by varying the amount of air in the spring. This allows an operator to tune the spring stiffness to their personal liking. 
   With reference to  FIGS. 5–7 , the suspension support rods  100  interconnecting the seat bracket  90  and equalizing bracket  95  to the suspension cams  120  describe arcuate paths as the suspension cams  120  rotate. The arcuate paths described by the suspension rods  100  interconnecting the seat bracket  90  to the suspension cams  120  have relatively large vertical components and relatively small horizontal components, which results in substantially vertical movement of the seat bracket  90 . The arcuate paths described by the suspension rods  100  interconnecting the equalizing bracket  95  to the suspension cams  120  have relatively large horizontal components and relatively small vertical components, which results in substantially horizontal movement of the equalizing bracket  95 . 
     FIG. 5  illustrates a default position for the suspension system  25 . This is characterized as the default position because the suspension system  25  is designed to assume this position in the absence of external forces (e.g., an operator seated on the seat and bumps and other dynamic forces arising from operation of the vehicle in which the seat is installed) acting on the suspension system  25 . Stated another way, the air spring  125  biases the seat bracket  90  to the default position in the absence of an overwhelming external force.  FIG. 7  illustrates the suspension system  25  in its full-down position, which is the end of the range of motion in which the seat bracket  90  is closest to the floor bracket  85  and in which the equalizing bracket  95  abuts the right range of motion limiter  137  as seen in  FIG. 7 .  FIG. 6  illustrates an intermediate position between the default and full-down positions of  FIGS. 5 and 7 . 
   When a vertical force is applied to the suspension system  25 , the floor bracket  85  and seat bracket  90  move toward each other against the biasing force of the air spring  125 . Such vertical forces may arise from sudden downward movement of the seat bracket  90  (due, for example, to an operator initially sitting on the seat  10 ), from sudden upward movement of the floor bracket  85  (due, for example, to the vehicle moving over a bump in the road), or from a combination of sudden downward movement of the seat bracket  90  and upward movement of the floor bracket  85 . As the seat bracket  90  and floor bracket  85  move toward each other, the air spring  125  deflects and the suspension cams  120  rotate counterclockwise as viewed in  FIGS. 5–7 . Once the vertical force is gone, the air spring  125  forces the seat bracket  90  and floor bracket  85  apart, and the cams  120  rotate clockwise as viewed in  FIGS. 5–7 . The space between the seat bracket  90  and the floor bracket  85  may oscillate as the air spring causes the seat bracket  90  to bounce up and down with respect to the floor bracket  85 . 
   In the illustrated embodiment, the shock absorber  130  resists sudden counterclockwise and clockwise rotation of the suspension cams  120  as viewed in  FIGS. 5–7 . Thus, the shock absorber  130  dampens downward and upward movement of the seat bracket  90  and consequently has a dampening effect on oscillatory air spring  125  movement. The shock absorber  130  also resists large deflections of the air spring  125  under extremely sudden and transient vertical forces that may cause the suspension system  25  to top or bottom out. In alternative embodiments, the shock absorber  130  may be sized, oriented, and mounted within the suspension system  25  in substantially any manner that resists sudden movement of the seat bracket  90  and floor bracket  85  toward and away from each other. 
   Various features and advantages of the invention are set forth in the following claims.