GB2229910A

GB2229910A - Seat reclining mechanism

Info

Publication number: GB2229910A
Application number: GB8907625A
Authority: GB
Inventors: Simon J Griffiths
Original assignee: IHW Engeneering Ltd; AJC Johnson Controls Ltd
Current assignee: AJC Johnson Controls Ltd
Priority date: 1989-04-05
Filing date: 1989-04-05
Publication date: 1990-10-10
Anticipated expiration: 2009-04-05
Also published as: GB2229910B; GB8907625D0

Abstract

A seat reclining mechanism comprises a cushion arm pivotally connected to a squab arm by a planetary gear arrangement which includes first and second ring gears located co-axially side by side and being fixed respectively to the squab arm and to the cushion arm, a drive shaft located co-axially relative to the ring gears carries at least one sun gear and at least one planetary gear drivingly located between the sun gear and both ring gears, said one planetary gear being axially located between opposed walls associated with the cushion and squab arms respectively. The planetary gear is deflectably located to permit deflection about its rotational axis when driven by relative movement between said ring gears, such deflection causing opposed side edges of the planetary gear to be moved into contact with said opposed walls, and locking formation associated with said opposed walls which co-operate with said opposed side edges of said planetary gear to restrain said relative rotational movement between said ring gears. <IMAGE>

Description

SEAT RECLINING MECHANISM The present invention relates to a seat reclining mechanism, and in particular relates to a seat reclining mechanism of the type having a cushion arm pivotally connected to a squab arm and a planetary gear arrangement drivingly connected therebetween for causing relative angular displacement between the cushion and squab arms.

With seat reclining mechanisms of the above type there is the possibility for the planetary gear arrangement to permit relative movement between the cushion and squab arms whilst under load and exposed to excessive vibration; such movement is hereinafter referred to as a regressive movement. It is a general aim to restrain regressive movement between a cushion and squab arm which are drivingly connected by a planetary gear arrangement.

According to one aspect of the present invention there is provided a seat reclining mechanism including a cushion arm pivotally connected to a squab arm by a planetary gear arrangement, the planetary gear arrangement including first and second ring gears located co-axially side by side, one ring gear being fixed to the squab arm and the other ring gear being fixed to the cushion arm, a drive shaft located co-axially relative to the ring gears and carrying at least one sun gear and at least one planetary gear drivingly located between the sun gear and both ring gears, said one planetary gear being axially located between opposed walls associated with the cushion and squab arms respectively, said one planetary gear being deflectably located to permit deflection about its rotational axis when driven by relative rotational movement between said ring gears, such deflection causing opposed side edges of the planetary gear to be moved into contact with said opposed walls, and locking formations associated with said opposed walls which co-operate with said opposed side edges of said planetary gear to restrain said relative rotational movement between said ring gears, said planetary gear co-operating with the sun gear such that when driven thereby the planetary gear is in a non deflected position such that said opposed side edges do not co-operate with said locking formations.

Preferably each ring gear is substantially the same diameter and has a different number of gear teeth.

Preferably three planetary gears are provided, all of which are deflectably located for deflection about their rotational axis.

Preferably each deflectable planetary gear includes at both axial ends an axially projecting annular shoulder of smaller diameter than the gear, said shoulders defining said opposed side edges.

Preferably a pair of opposed sun gears are provided of generally frusto conical shape which are axially biased towards one another, the opposed sun gears being located axially either side of the planetary gears.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which: Figure 1 is a schematic side view, partly broken away of an embodiment according to the present invention Figure 2 is a schematic axial sectional view of the embodiment illustrated in Figure 1 Figure 3 is a schematic prospective view of the embodiment as shown in Figure 1 Figure 4 is a schematic partial sectional view taken along line IV - IV in Figure 1 The seat reclining mechanism 10 includes a planetary gear arrangement 20 which pivotally connects a cushion arm 12 to a squab arm 14.

The cushion arm 12 and squab arm 14 are preferably of plate like metal pressings which are provided with integral ring gears 15, 16 respectively. The ring gears 15, 16 are formed by a pressing operation in which a central wall portion 17, 18 respectively is off-set. As seen in Figure 2, the arms 12, 14 are arranged side by side in face to face contact and the wall portions 17, 18 are spaced apart to define a housing for the planetary gears 24 and sun gear means 26.

A drive shaft 30 passes through the arms 12, 14 and is located co-axially relative to the ring gears 15, 16.

A pair of opposed, frusto conical sun gears 27 are slidably received on the drive shaft and are axially biased by means of associated springs 28 located therebetween and a respective shoulder 29 fixed secured on the shaft 30. Each sun gear 27 is rotationally fixed relative to the shaft 30; this is achieved by the shaft 30 having a non-circular cross-section and each sun gear having a bore of complementary shape.

Preferably three planetary gears 24 are provided which are equally spaced about the circumference of the sun gears 27. Each planetary gear 24 provides a driving connection between the sun gears 27 and both ring gears 15, 16. Each planetary gear 24 is free to float ie it is not secured by a stab shaft to either arm 12, 14; its rotational position is maintained by intermeshing of teeth with the sun and ring gears 15, 16. Each planetary gear 24 is located between opposed wall portions 17, 18 and its axial extent is slightly less than the spacing between wall portions 17, 18.

Each planetary gear 24 is provided with annular shoulders 25 which protrude in opposite axial directions from opposite axial ends of the gear 24.

The shoulders 25 have square side edges 35. Each opposed wall portion 17, 18 is provided with annular locking formations defined by an annular surface formation 38. Each surface formation 38 includes a series of semi-circular ridges 39 separated by depressions 40 to thereby define a series of shoulders 41 (Figure 4).

The axial spacing between the planetary gears 24 and opposed walls 17, 18 is chosen to enable the planetary gears 24 to deflect about their rotational axies when relative movement between the ring gears 15, 16 attempts to drive the planetary gears 24. Such deflection moves opposed side edges 35 of the planetary gears 24 into contact with shoulders 41. This situation is illustrated in Figure 4.

The shoulders 41 on wall 17 face in the opposite circumferencial direction to shoulders 41 on wall 18 and the deflected planetary gear 24 in located therebetween.

Further relative rotational movement of the ring gears 15, 16 attempts to deflect the planetary gear further and this is prevented by the opposed wall portion 17, 18. Thus the squab and cushion arms are prevented from undergoing a regressive movement.

During adjustment of the seat reclining mechanism rotation of the sun gears 27 causes the planetary gears to be centralised and so releases the side edges 35 from shoulders 41 and enables the cushion and squab arms to be adjusted normally.

Claims

1. A seat reclining mechanism including a cushion arm pivotally connected to a squab arm by a planetary gear arrangement, the planetary gear arrangement including first and second ring gears located co-axially side by side, one ring gear being fixed to the squab arm and the other ring gear being fixed to the cushion arm, a drive shaft located co-axially relative to the ring gears and carrying at least one sun gear and at least one planetary gear drivingly located between the sun gear and both ring gears, said one planetary gear being axially located between opposed walls associated with the cushion and squab arms respectively, said one planetary gear being deflectably located to permit deflection about its rotational axis when driven by relative rotational movement between said ring gears, such deflection causing opposed side edges of the planetary gear to be moved into contact with said opposed walls, and locking formations associated with said opposed walls which co-operate with said opposed side edges of said planetary gear to restrain said relative rotational movement between said ring gears, said planetary gear co-operating with the sun gear such that when driven thereby the planetary gear is in a non deflected position such that said opposed side edges do not co-operate with said locking formations.

2. A seat reclining mechanism according to Claim 1, wherein each ring gear is substantially the same diameter and has a different number of gear teeth.

3. A seat reclining mechanism according to Claim 1 or 2, wherein at least three planetary gears are provided, all of which are deflectably located for deflection about their rotational axis.

4. A seat reclining mechanism according to any preceding claim wherein each deflectable planetary gear includes at both axial ends an axially projecting annular shoulder of smaller diameter than the gear, said shoulders defining said opposed side edges.

5. A seat reclining mechanism according to Claim 4, wherein each locking formation comprises an annular surface formation including a series of semi-circular ridges separated by depressions.

6. A seat reclining mechanism according to any preceding Claim, wherein a pair of opposed sun gears are provided of generally frusto conical shape which are axially biased towards one another, the opposed sun gears being located axially either side of the planetary gears.