Chair backrest linkage mechanism

• US 4,943,114 A
• Filed: 02/06/1989
• Issued: 07/24/1990
• Est. Priority Date: 02/06/1989
• Status: Expired due to Fees

• Current Assignee: Giancarlo Piretti
• Original Assignee: Giancarlo Piretti
• Inventors: Piretti, Giancarlo
• Primary Examiner(s): Brown, Peter R.
• Application Number:
  US07/307,005
• Time in Patent Office: 533 Days
• Field of Search: 297/301, 297/302, 297/300, 297/316, 297/320, 297/340, 297/342, 403/61, 403/80
• US Class Current: 297/300.2
• CPC Class Codes: A47C 7/44 with elastically-mounted back-rest or backrest-seat unit in the base frame
• CPC Class Codes: A47C 7/443 with coil springs
• CPC Class Codes: A47C 7/444 of torsion type
• CPC Class Codes: A47C 7/445 with bar or leaf springs
• CPC Class Codes: Y10T 403/32073 Pivot stud slidable in elongated opening
• CPC Class Codes: Y10T 403/32229 Articulate joint is a slide

Abstract

A chair includes a compact backrest linkage mechanism for enabling the chair backrest and seat to tilt. The linkage mechanism comprises a pair of backrest levers pivotally connected to respective chair frame members near the chair back legs. A seat lever is pivotally connected to each chair frame member near the front legs. The backrest lever and seat lever pivotally connected to each chair frame member are connected to each other by an anti-friction sliding joint. Springs acting between the seat levers and chair frame members bias the seat levers and backrest levers to a normal configuration where the seat levers and backrest levers are positively located. A person sitting in the chair can tilt the backrest and simultaneously pivot the seat in only one direction from the normal configuration, that direction being to tilt the backrest backwardly and to raise the back end of the seat.

Claims

1. A backrest linkage mechanism comprising:

a. an elongated frame;

b. a backrest lever having a first end pivotally mounted to the frame and a second end;

c. a seat lever having a first end pivotally mounted to the frame and a second end;

d. an anti-friction sliding joint connecting the second ends of the backrest lever and the seat lever; and

e. spring means acting between the frame and at least one of the backrest lever and seat lever for biasing the backrest lever and seat lever to a normal configuration whereat the second end of at least one of the backrest lever and the seat lever is in abutting contact with the frame to locate the backrest lever and the seat lever in their respective normal configurations and whereat the seat lever and backrest lever are generally coplanar,

whereby exerting a force on the backrest lever against the spring means causes the backrest lever and the seat lever to pivot about the frame to a tilted configuration whereat the backrest lever and seat lever are non-coplanar.

2. The backrest linkage mechanism of claim 1 wherein:

a. the frame is generally channel-shaped with a bottom wall and two spaced side walls; and

b. the backrest lever and seat lever are substantially completely nested within the frame when the spring means biases the backrest lever and seat lever to the normal configuration.

3. A backrest linkage mechanism comprising:

a. an elongated frame;

b. a backrest lever having a first end pivotally mounted to the frame and the second end;

c. a seat lever having a first end pivotally mounted to the frame and a second end;

d. an anti-friction sliding joint connecting the second ends of the backrest lever and the seat lever; and

e. spring means acting between the frame and at least one of the backrest lever and seat lever for biasing the backrest lever and seat lever to a normal configuration whereat the second end of at least one of the backrest lever and the seat lever is in abutting contact with the frame to locate the backrest lever and the seat lever in their respective normal configurations and whereat the seat lever and backrest lever are generally coplanar, wherein the spring means comprises;

i. a post fixed to the seat lever and defining at least one hole therein;

ii. a pin fixed to the frame; and

iii. a torsion spring guided on the pin and having an end leg that is received in the post hole,

where by exerting a force on the backrest lever against the spring means causes the backrest lever and the seat lever to pivot about the frame to a tilted configuration whereat the backrest lever and seat lever are non-coplanar.

4. A chair comprising:

a. a pair of front legs and a pair of back legs;

b. a pair of spaced frame members connecting corresponding front legs and back legs to each other near the

c. a pair of seat levers, each seat lever having a first end pivotally mounted to a respective frame member near the front leg and a second end;

d. a pair of backrest levers, each backrest lever having a first end pivotally mounted to a respective frame member near the back leg and a second end;

e. an anti-friction sliding joint connecting the respective second ends of the seat levers and backrest levers to each other;

f. a seat fastened to the seat levers;

g. a backrest upstandingly attached to the backrest levers; and

h. spring means coacting between each seat lever and the respective frame member for biasing the seat levers and backrest levers to a normal configuration whereat the seat is in a generally horizontal attitude and the backrest is in a generally vertical attitude and the seat levers and backrest levers are generally coplanar,

whereby exerting a force on the backrest against the spring means causes the backrest levers and the seat levers to pivot about their respective first ends to a tilted configuration whereat the backrest levers and the seat levers are non-coplanar.

5. The chain of claim 4 wherein the frame members are generally channel-shaped, and wherein the seat levers and backrest levers are nested substantially completely within the respective frame members when the spring means biases the seat levers and backrest levers to their respective normal configurations.

6. A chain comprising:

a. a pair of front legs and a pair of back legs;

b. a pair of spaced frame members connecting corresponding front legs and back legs to each other near the respective top ends thereof;

a pair of seat levers, each seat lever having a first end pivotally mounted to a respective frame member near the front leg and a second end;

d. a pair of backrest levers, each backrest lever having a first end pivotally mounted to a respective frame member near the bag leg and a second end;

e. an anti-friction sliding joint connecting the respective second ends of the seat levers and backrest levers to each other;

f. a seat fastened to the seat levers;

g. a backrest upstandingly attached to the backrest levers; and

h. spring means coacting between each seat lever and the respective frame member for biasing the seat levers and backrest levers to a normal configuration whereat the seat is in a generally horizontal attitude and the backrest is in a generally vertical attitude and the seat levers and backrest levers are generally coplanar, wherein the spring means comprises;

i. a post fixed to each seat lever and having at least one hole therein;

ii. a torsion spring guided on the pin in each frame member and having respective end legs that are received in the corresponding seat lever post holes.

7. In combination with a chain having a seat, a backrest, front and back legs, and at least one longitudinally extending frame member for joining the front and back legs near the top ends thereof;

at least one backrest linkage mechanism comprising;

a. a seat lever supporting the seat and having a first end pivotally mounted to the chair frame member near the front leg thereof and a second end;

b. a backrest lever supporting the backrest and having a first end pivotally mounted to the frame member near a chair back leg and a second end;

c. an anti-friction sliding joint connecting the second ends of the seat and backrest levers to each other; and

d. spring means coacting between the seat lever and the frame member for biasing the backrest lever and seat lever to a normal configuration whereat the seat lever and backrest lever are generally coplanar,

whereby applying a force on the backrest against the spring means overcomes the biasing thereof to pivot the backrest lever and the seat lever to a tilted configuration whereat the seat lever and backrest lever are non-coplanar.

8. The combination of claim 7 wherein the second end of at least one of the seat lever and the backrest lever is in abutting contact with the chair frame member to locate the backrest lever and seat lever in the normal configuration.

9. The combination of claim 7 wherein the seat lever and backrest lever lie nested substantially completely within the chair frame member when they are biased to their respective normal configurations.

10. In combination with a chair having a seat, a backrest, front and back legs, and at least one longitudinally extending frame member for joining the front and back legs near the top ends thereof,

at least one backrest linkage mechanism comprising:

a. a seat lever supporting the seat and having a first end pivotally mounted to the chair frame member near the front leg thereof and a second end;

b. a backrest lever supporting the backrest and having a first end pivotally mounted to the frame member near a chair back leg and a second end, wherein

the backrest lever and seat lever are formed as elongated generally channel-shaped members having respective opposed side walls,

and wherein the opposed side walls of the second end of a selected one of the backrest lever and seat lever are formed with tapered sections that terminate in side wall end portions that fit between the side walls of the other of the selected backrest lever and seat lever,

and wherein at least one of the side walls at the second end of the selected one of the backrest lever and seat lever defines a slot therein;

c. an anti-friction sliding joint connecting the second ends of the seat and backrest levers to each other, wherein an anti-friction bearing block is received in the slot in the selected one of the seat lever or backrest lever, and

a pin passes through the anti-friction bearing block and is secured in the side walls of the other of the selected backrest lever and seat lever; and

d. spring means coacting between the seat lever and the frame member for biasing the backrest lever and seat lever to a normal configuration whereat the seat lever and backrest lever are generally coplanar,

so that the slots, anti-friction bearing block, and pin cooperate to form the anti-friction sliding joint and thereby enable the backrest lever and seat lever to pivot and slide relative to each other when the backrest lever and seat lever pivot in the frame member at the respective first ends thereof.

11. The combination of claim 10 wherein:

a. the side walls of the second end of the seat lever are formed with tapered sections that terminate in respective end portions that fit between the side walls of the backrest lever;

b. the side walls of the seat lever at their respective end portions are formed with slots; and

c. the anti-friction bearing block is received in a slot in the seat lever.

12. The combination of claim 11 wherein:

a. the anti-friction sliding joint comprises two anti-friction bearing blocks, an antifriction bearing block being received in the slot of each side wall of the seat lever; and

b. the pin is secured in the side walls of the backrest lever.

13. The combination of claim 10 wherein the anti-friction bearing block comprises:

a. a hub passing through a slot in the selected one of the seat lever or backrest lever, the hub defining a hole therethrough for receiving the pin; and

b. a flange extending outwardly from the hub, the flange being interposed between a side wall of the seat lever and a side wall of the backrest lever.