Constant force generator mechanism and adjustable seat constructed therewith

• US 4,387,876 A
• Filed: 07/01/1981
• Issued: 06/14/1983
• Est. Priority Date: 05/05/1979
• Status: Expired due to Fees

• Current Assignee: Advanced Products Beer-Sheva Limited
• Original Assignee: Advanced Products Beer-Sheva Limited
• Inventors: Nathan, Roger H.
• Primary Examiner(s): McCall, James T.
• Application Number:
  US06/279,408
• Time in Patent Office: 713 Days
• Field of Search: 267/131, 267/182, 248/571, 248/280.1, 248/281.1, 248/421, 297/345, 297/DIG. 10
• US Class Current: 248/571
• CPC Class Codes: A47C 3/20 Chairs or stools with vertically-adjustable seats tables with variable height A47B9/00
• CPC Class Codes: A47C 3/22 with balancing device, e.g. by spring, by weight
• CPC Class Codes: B60N 2/507 Parallelogram-like structure
• CPC Class Codes: B60N 2/544 Compression or tension springs B60N2/542 takes precedence
• CPC Class Codes: F16F 1/12 Attachments or mountings F16F1/041, F16F13/02 take precedence; of combinations of vibration damper and mechanical spring for vehicle suspension units B60G15/02
• CPC Class Codes: F16F 2230/0011 Balancing, e.g. counterbalancing to produce static balance
• CPC Class Codes: F16M 2200/04 Balancing means
• CPC Class Codes: F16M 2200/063 Parallelogram arms

Abstract

A constant force generator mechanism is described, comprising a rigid first link adapted to be fixed to a support, a rigid second link mounted for pivotable movement to the first link by a first hinge joint, and a spring link hingedly mounted to the first link by a second hinge joint and hingedly mounted to the second link by a third hinge joint. The spring link is one having a linear spring rate and a zero free length whereby, upon pivotting the second link with respect to the first link, the spring link generates a force whose component parallel to the first link at any given point on the second link is constant through the entire range of pivotable movement of the second link.

Also described is a chair having a seat continuously adjustable by the above constant force generator mechanism.

Claims

1. A constant force generator mechanism, comprising:

a rigid first link adapted to be fixed to a support;

a rigid second link mounted for pivotable movement to said first link by a first hinge joint; and

a spring link hingedly mounted to said first link by a second hinge joint, and hingedly mounted to said second link by a third hinge joint;

said spring link having a linear spring rate and zero free length whereby, upon pivoting the second link with respect to the first link, the spring link generates a force whose component parallel to the first link at any given point on the second link is constant through the entire range of pivotable movement of the second link, said second hinge joint being adjustable on said first link to vary the magnitude of the generated force.

2. The mechanism according to claim 1, wherein said spring link comprises a spring fixed at one end to said first link and attached at its opposite end to one end of a force-transmitting member, the opposite end of the force-transmitting member being attached to said second link such as to deform said spring upon pivotting the second link away from the first link.

3. The mechanism according to claim 1, wherein said spring link comprises a spring disposed within a housing hingedly mounted to said first link and constituting said second hinge joint, said housing including a force-transmitting member hingedly mounted at one end to said second link and constituting said third hinge joint, the opposite end of the force-transmitting member being coupled to said spring to deform same upon pivotting the second link away from the first link.

4. The mechanism according to claim 1, wherein the adjustable hinge joint is automatically adjustable by feedback from the external force to produce an equilibrium between the external force and the generated force.

5. The mechanism according to claim 1, further including a rigid third link parallel to said first link, and a rigid fourth link parallel to said second link, said third and fourth links being hingedly joined to said first and second links to form a four-bar parallelogram linkage therewith.

6. The mechanism according to claim 5, further including an additional four-bar parallelogram linkage, wherein said third link is common to both of said parallelogram linkages, said additional four-bar parallelogram linkage including an additional spring link having a linear spring rate and a zero free length hingedly mounted to said common third link and another rigid link of the additional parallelogram linkage.

7. A chair having a seat continously adjustable in height with respect to a frame, and including a constant force generator mechanism according to claim 1, said first link being fixed to the chair frame, and the chair seat being coupled to said second link such that the weight on the seat is parallel to said first link.

8. The chair according to claim 7, wherein said constant force generator mechanism further includes a rigid third link parallel to said first link, and a rigid fourth link parallel to said second link, said third and fourth links being hingedly joined to said first and second links to form a four-parallelogram linkage therewith.

9. The chair according to claim 8, further including manual adjusting means for manually adjusting said third hinge joint of the spring link along said second link to vary the magnitude of the force generated by said spring link.