Seat suspension with cam support member and spring assisted height adjustment

• US 5,125,631 A
• Filed: 03/20/1990
• Issued: 06/30/1992
• Est. Priority Date: 02/01/1989
• Status: Expired due to Term

• Current Assignee: Sears Manufacturing Co.
• Original Assignee: Sears Manufacturing Co.
• Inventors: Foster, Danny S., Brodersen, Cole T.
• Primary Examiner(s): Oberleitner, Robert J.
• Application Number:
  US07/496,875
• Time in Patent Office: 833 Days
• Field of Search: 267/131, 267/182, 248/421, 248/500, 248/566, 248/575, 248/584, 248/585, 248/588, 248/608, 248/564, 297/347
• US Class Current: 267/131
• CPC Class Codes: B60N 2/502 attached to the base of the seat B60N2/504 takes precedence
• CPC Class Codes: B60N 2/505 Adjustable suspension including height adjustment
• CPC Class Codes: B60N 2/506 Seat guided by rods
• CPC Class Codes: B60N 2/508 Scissors-like structure
• CPC Class Codes: B60N 2/509 Seat guided by slides or the like
• CPC Class Codes: B60N 2/544 Compression or tension springs B60N2/542 takes precedence

Abstract

A mechanical seat suspension inside a housing comprises parallel scissor arms and a support arm with a cam connected to suspension springs. The support arm, which carries the substantial majority of the seat load, has a height adjustment mechanism and a cam with two arcuate surfaces that define an imaginary pivot point. The use of the cam with the imaginary pivot point permits a more compact structure. Various embodiments of the support arm with a cam end and devices using the support arm are also disclosed. A shock absorber attached to the outside of the scissor arms dampens the stroke of the suspension springs connected to the cam. The ratio of the shock stroke travel to the vertical movement of the seat remains generally linear and constant, thus producing a more comfortable ride. Also included is a height adjustment mechanism on the support arm that interlocks with the cam by a pivoting pawl and biasing spring. The height of the seat is adjusted by the relative movement of the top portion of the housing to the lower portion. No external levers, triggers, or other structures are mecessary for seat adjustment. The tension in the suspension springs is adjustable to compensate for the weight of the rider. Another embodiment of the suspension includes a support assembly with two support arms that move relative to a cam that can be latched in five positions. Compression springs connected to the support assembly and disengaging arms with a disengaging roller permit a power assisted height adjustment.

Claims

1. An angularly displaceable support assembly for use in a suspension system that maintains two surfaces in generally parallel spaced relation, comprising:

at least one shaft with first and second ends;

a cam movably connected to said first end to effect the spacing of the two parallel spaced surfaces, said cam having a larger arcuate surface and a smaller arcuate surface, said cam surfaces defining a point about which said cam pivots as said shaft is angularly displaced;

means for securing said shaft and said cam in fixed engagement;

means for moving said shaft relative to said cam when said cam and said shaft are disengaged;

means disposed at said second end of said shaft for permitting angular displacement of aid shaft as the distance between the two parallel spaced surfaces changes; and

means for operatively connecting said shaft and said cam to the suspension system.

2. The support assembly of claim 1 wherein said means for securing said cam and said shaft further comprises a rod connectable to a biasing device in the suspension system.

3. The support assembly of claim 1 wherein said means for moving said shaft relative to said cam includes a compression spring.

4. A suspension system for maintaining two surfaces in generally parallel relation, at least one of the surfaces being moveable with respect to the other, comprising:

a shaft operatively connected to and angularly displaceable between the two surfaces;

a cam movably connected to one end of said shaft, said cam having a larger arcuate surface and a smaller arcuate surface, said surfaces defining a center point;

means for disengaging said cam and said shaft;

cam follower means for defining the movement of said cam and said shaft as the one surface moves;

biasing means operatively connected to said shaft for controlling the relative movement of said shaft to said cam for adjusting the height of the one moveable surface; and

means for biasing the one moveable surface in relation to the other surface.

5. A suspension system, comprising:

a first support surface and a second support surface, generally parallel to each other;

a pair of support arms angularly disposed between and movably connected between said first and second surfaces;

a cam located at one end of and between said support arms, said cam being in pivotal relation to and operative connection with said first surface, and said cam having a larger arcuate surface and a smaller arcuate surface that define a center point about which said cam pivots;

means for holding said cam and said support arms in fixed engagement;

means for disengaging said support arms from said cam;

a first biasing means for moving said support arms relative to said cam to adjust the height of said first surface;

cam follower means in operative contact with each of said arcuate surfaces for controlling the movement of said cam as one of said surfaces moves relative to the other of said surfaces;

means located at the other end of said support arms and in operative connection with said second surface for permitting a change in the angular disposition of said support arm while said first and second surfaces move relative to each other; and

a second biasing means in operative engagement with said support arms, with said cam and with said first biasing means for providing a suspension force in the suspension system.

6. The apparatus of claim 5 wherein said first biasing means is a compression spring.

7. The apparatus of claim 5 wherein said second biasing means is an extension spring.

8. The apparatus of claim 5 wherein said cam includes latch means engageable with pins connecting said support arms.