GB2264146A

GB2264146A - Seat reclining mechanism

Info

Publication number: GB2264146A
Application number: GB9202984A
Authority: GB
Inventors: Simon Jonathan Giles Griffiths
Original assignee: IHW Engeneering Ltd; AJC Johnson Controls Ltd; Adwest Johnson Controls Ltd
Current assignee: AJC Johnson Controls Ltd
Priority date: 1992-02-13
Filing date: 1992-02-13
Publication date: 1993-08-18
Anticipated expiration: 2012-02-13
Also published as: FR2687354A1; FR2687354B1; DE4302605A1; GB2264146B; JPH0622827A; GB9202984D0

Description

2264146 1 The present invention relates to a seat reclining mechanism, in

particular but not exclusively, a vehicle seat reclining mechanism.

Seat reclining mechanisms of the gear driven type typically include first and second members pivotally connected to one another and a gear transmission drivingly connected to the first and second members, the gear transmission including an input shaft which on rotation causes the first and second members to be pivotally moved 10 relative to one another.

In such seat reclining mechanism there tends to be a degree of play between the first and second members about the pivot axis due to clearances in the gear transmission. In view of this play there is a tendency for a seat back or squab to judder as it is moved in the recline direction particularly if the input shaft to the reclining mechanism is operated quickly.

It is a general aim of the present invention to eliminate or substantially reduce juddering when operating a gear driven type seat reclining mechanism.

According to one aspect of the present invention there is provided a seat reclining mechanism including first and second members pivotally connected to one another and a gear transmission drivingly connected to the first and second members, the gear transmission including an input shaft which, on rotation in one direction, causes the first and second members to move angularly apart in a reclining direction and biasing means operably connected to the first 2 and second members to provide a biasing f orce opposing movement of the first and second members in the reclining direction.

According to another aspect of the present invention there is provided a seat, preferably a vehicle seat, having a seat cushion pivotally connected to a seat back by a seat reclining mechanism including first and second members pivotally connected to one another and a gear transmission drivingly connected to the first and second members, the first member being connected to the seat cushion and the second member being connected to the seat back, the gear transmission including an input shaft which on rotation in one direction causes the first and second members to move angularly apart in a reclining direction to cause the seat back to move in said reclining direction relative to the seat squab and biasing means arranged to provide a biasing force opposing movement of the seat back in said reclining direction.

Preferably, the biasing means is arranged to progressively increase biasing force in relation to an increase in the angular displacement between the first and second members in the recline direction.

The seat back is arranged to move between a f ully upright position to a fully reclined position and the biasing means is arranged to provide a biasing force which is preferably about 50 to 100%, more preferably about 75 to 90% of the gravitational biasing force created by the weight of the seat back at any position between said fully 3 upright and reclined positions.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic side view of a reclining seat; Figure 2 is a perspective view of a seat reclining mechanism according to one embodiment of the present invention; Figure 3 is an axial section of part of the mechanism shown in Figure 2.

Referring únitially to Figure 1 there is shown a reclining seat 10 having a seat cushion 12 pivotally connected to a seat back 14 by one or a pair of seat reclining mechanisms (not shown in Figure 1) of the gear type as previously described.

operation of the seat reclining mechanism(s) moves the seat back 14 relative to the seat cushion 12 between a fully upright position FU and a fully reclined position FR.

The seat back 14 is illustrated as being located at an intermediate position IP.

In view of tolerances within the gear transmission the seat back 14 may be freely movable between positions PP and IP ie there is f ree play between the seat cushion 12 and seat back 14 over the angular range between positions PP and IP. In normal use, the seat back 14 resides in position IP due to the gravitational bias created by the weight of the seat back 14.

4 If the seat reclining mechanism is operated to move the seat back 14 toward its fully reclined position vibration in the reclining mechanism occurs and if this vibration occurs at the natural frequency of the seat back, 5 the seat back resonates causing it to judder.

In accordance with the present invention a biasing means is provided which provides i biasing force to oppose the movement of the seat back 14 towArd the fully reclined position FP such that the vibration caused on such movement is maintained outside the natural frequency range of the seat back and therefore prevents the seat back from resonating.

The biasing means, which may be a torsion or tension spring, may be directly connected between the seat cushion 12 and seat back 14 and/or may be incorporated in the seat reclining mechanism.

Preferably the biasing force created by the biasing means progressively increases as the seat back 14 moves progressively closer to the fully reclined position FP in order to compensate for the progressive increase in gravitational bias created by the weight of the seat back. The biasing means is preferably arranged to create a biasing force which is equal to or less than the gravitational biasing force created by the weight of the seat back 14 at any position between positions FU and FR. In this way the weight of the seat back will always ensure that the seat back 14 is in position IP- and not PP (or a position intermediate IP and PP). Preferably the biasing 1 force of the biasing means is in the range of 50 to 100%, more preferably 75 to 90% of the gravitational biasing force created by the weight of the seat back.

In Figures 2 and 3 there is shown a seat reclining mechanism 50 according to one embodiment of the present invention. The mechanism 50 includes a first member 51 for connection to the seat cushion 12 and a second member 52 for connection to the seat back 14. The first and second members are pivotally connected by a gear transmission 55 having an input shaft (not shown) driven by a handle 56. The reclining mechanism 50 may be of a construction similar to that disclosed in our UK patent 1586869 or European patent specification 332340. The reclining mechanism 50 includes a biasing means 60 preferably in the form of a coiled spring 61 supported on a bobbin 62 (not shown in Figure 2) mounted on the first member 51. one end 63 of the spring is anchored to the first member 51, preferably being located in an aperture 20 59, and opposite end 64 abuts against an arm 57 mounted on the second ember 52. The coiled spring 61 is arranged such that angular movement between the first and second member tends to force ends 63,64 in opposite directions to uncoil the spring.

This has the effect of increasing torsional resistance to such movement and so increases the biasing affect of the spring 61. Thus at position FU the spring 61 creates a minimum biasing force and at position FR creates a maximum biasing force.

6

Claims

1. A seat reclining mechanism including first and second members pivotally connected to one another and a gear transmission drivingly connected to the first and second members, the gear transmission including an input shaft which, on rotation in one direction, causes the first and second members to move angularly apart in a reclining direction and biasing means operably connected to the f irst and second members to provide a biasing force opposing movement of the first and second members in the reclining direction.

2. A seat reclining mechanism according to claim 1, wherein the biasing means is arranged to progressively increase the biasing force in relation to an increase in the angular displacement between the first and second members in the recline direction.

3. A seat reclining mechanism according to claim 1 or 2, wherein the biasing means is a torsion spring.

4. A seat reclining mechanism according to claim 3, 20 wherein thebiasing means in a tension spring.

5. A seat reclining mechanism according to claim 3, wherein the torsion spring comprises a coiled spring having one end anchored to the first member and an opposite end anchored to the second member.

6. A seat having a seat cushion pivotally connected to a seat back by a seat reclining mechanism according to any preceding claim.

7. A seat having a seat cushion pivotally connected to a seat back by a seat reclining mechanism including f irst and second members pivotally connected to one another and a gear transmission drivingly connected to the first and second members, the first member being connected to the seat cushion and the second member being connected to the seat back, the gear transmission including an input shaft which on rotation in one direction causes the first and second members to move angularly apart in a reclining direction to cause the seat back to move in said reclining 7 direction relative to the seat squab and biasing means arranged to provide a biasing force opposing movement of the seat back in said reclining direction.

8. A seat according to claim 6 or 7, wherein the biasing means are connected between the seat cushion and seat back.

9. A seat according to claim 6,7 or 8, wherein the seat back is arranged to move between a fully upright position and a fully reclined position, the biasing means is arranged to provide a biasing force which is about 50-100% of the gravitational force created by the weight of the seat back at any position between said fully upright and fully reclined positions.

10. A seat according to claim 9, wherein the biasing means is arranged to provide a biasing force which is about 75- 90% of the gravitational biasing force created by the weight of the seat back at any position between said fully upright and fully reclined positions.