GB2149005A - Adjustment mechanisms - Google Patents

Abstract

An adjustment mechanism allowing controlled relative angular adjustment between two members such as a vehicle seat back and seat portion is provided. The mechanism comprises first and second plate members (11, 12) in adjacent overlapping face to face disposition secured together by a sleeve (22) passing through aligned apertures (15, 16) therein. An annular space (19) between the plates (11, 12) houses two sprag clutches (13) having oval sprag elements (28, 29) each of which has a major axis sufficient for the element (18, 29) to bridge the space (19) and engage an annular surface (31, 32) provided on the plates (11, 12). A hand wheel (37) has pins (43) passing through slots (44) in plate (11) to engage slots (45, 46) in the sprags (28, 29) to disengage them from the respective surface (31, 32) and allow relative angular motion between plates (11, 12). <IMAGE>

Description

SPECIFICATION Adjustment mechanisms The invention concerns adjustment mechanisms, and has more particular reference to mechanisms adapted to allow of the controlled adjustment of the relative angular disposition of two coaxially mounted parts.

One particular application of the adjustment mechanism is in the context of a reclining mechanism for a motor vehicle seat, although such mechanism is believed to have application in other contexts and fields.

In is known in the art to provide a seat reclining mechanism which comprises two coaxially mounted plates for respective application to the seat portion and backrest portion of the vehicle seat and an epicyclic gear arrangement interposed therebetween, such epicyclic gear arrangement including a gear ring on each respective plate drivingly connected together by an eccentrically mounted, double planet gear in drive engagement with both gear rings, actuation of an adjustment handle effecting motion of the planet gears peripherally of the gear rings with which the same are respectively engaged and adjustment of the angular disposition of the plates at a rate determined by the gear ratios of the individual elements of the epicyclic gear arrangement.In practice, multiple rotations of the adjustment handle are necessary to effect any substantial relative angular adjustment of the seat portion and backrest portion, and this often proves to be both inconvenient and difficult having regard to the weight of the seat back portion, notwithstanding that spring means is provided to support the seat back during adjustment.

In an alternative arrangement, an internal gear and a plurality of angularly located radially adjustable toothed locking members intended for selective engagement with the said internal gear are provided on the respective plates, there being a spring-loaded handle means adapted, accordingly to its angular position, to determine engagement or otherwise of the locking members with the internal gear to prevent or permit relative angular adjustment of tlSe plates.Whilst this particular reclining mechanism avoids the problems inherent in the previously identified mechanism, it does itself have disadvantages, the principal one of which is that, on disengagement of the locking members from the internal gear, the seat back portion is not supported against pivotal motion and angular adjustments of significant proportions can inadvertently be effected, such large scale adustment, in the event that adjustment is sought to be made by the driver whilst the vehicle is in motion, possibly resulting in the driver losing control of the vehicle.

The object of the present invention is to provide an alternative adjustment mechanism to those hitherto used which avoids the problems inherent in the prior structures.

According to the present invention there is proposed an adjustment mechanism comprising two angularly adjustable, coaxially arranged members for respective attachment to the structures between which angular adjustment is required, releasable locking means between and selectively operably engageable with the said members, and adjustment means engaged with one member and adapted to effect release of the locking means and angular movement of the said one member relative to the other member upon actuation of such means.

According to a preferred feature, the locking means includes oppositely directed sprag clutch arrangement providing for controlled adjustment of the relative angular disposition of the said members in each of two opposite directions.

According to a further preferred feature, the adjustment means includes a lost motion to allow of the release of the locking means before initiating relative angular movement between the said members.

The invention will now be described further, by way of example only, with reference to the accompanying drawings illustrating one embodiment thereof and in which: Figure 1 is a section through an adjustment mechanism constructed in accordance with the invention; and Figure 2 is a section on line ll-ll of Fig. 1.

Referring now to the drawings, a reclining mechanism for a vehicle seat comprises first and second plate members 11, 1 2 arranged in closely adjacent overlapping face-to-face disposition, locking means 1 3 between and selectively operably engageable with the plate members 11, 12, and adjustment means 14 engaged with the plate member 1 2 and, upon actuation, successively to release the locking means 1 3 and effect angular adjustment of the said first plate member 11 relative to the second plate member 1 2.

Both plate members 11, 1 2 are of oval form when viewed in plan and of stepped configuration when viewed in longitudinal section. Aligned apertures 15, 1 6 are provided in the two plate members 11, 1 2 and centrally of the overlapped regions thereof, the plate member 1 2 having an axially directed flange 1 7 about such aperture 1 6 which extends to a position closely adjacent to the opposing face 1 8 of the plate member 1 2 and the plate member 1 2 being dished about the aperture 1 5 therein to provide an annular space 1 9 between the plates 11, 1 2 and coaxially with the aligned apertures 15, 1 6. The plate mem ber 1 2 includes a rib 20 for engagement with a corresponding groove 21 in the plate mem ber 11, the rib 20 and groove 21 being coaxial with the apertures and locating the first and second plate members for relative angular adjustment about the axis thereof.

The first and second plate members 11, 1 2 are secured together by a sleeve 22 engaged with the aligned apertures, a radial flange 23 on the sleeve 22 cooperating with an opposed lip 24 on flange 1 7 to prevent outward movement of the first plate member 11 in one direction and a circlip 25 located in a groove 26 in the sleeve 23 and bearing against the outer face of the second plate member 1 2 preventing outward movement of such plate member 1 2. A ball bearing arrangement 27 is interposed between the radial flange 23 and opposing lip 24 to facilitate relative angular motion between the plates.

The locking means 1 3 consists of two sprag clutches having the elements thereof arranged alternately and in opposed disposition, each sprag body 28, 29 being of oval form and of such major dimension as to bridge the annular space 19 defined by and between the first and second plate members 11, 1 2. The individual sprag bodies 28, 29 are held in engagement with the opposing axially directed cylindrical surfaces 31, 32 of the annular space 1 9 by profiled springs, 33, 34, such springs 33, 34 engaging lugs 35, 36 which extend from the face of each such body, inner spring 33 loading the sprag bodies 28, 29 into contact with the inner surface 31 of the annular space by virtue of its cooperative engagement with correspondng lugs 35 at one end of the sprag bodies 28, 29 and outer spring 34 serving to maintain contact between such bodies 28, 29 and the outer surface 32 of the annular space 1 9 by cooperative engagement with the corresponding lugs 36 at the radially outermost end of the sprag bodies.

The adjustment means 14 comprises a handwheel 37 having a central boss 38 which extends through the sleeve 22 and is axially located relative thereto by a circlip 39 engaged with a circumferential groove 40 in the boss 38 and bearing on the annular end face 41 of the sleeve 22, the opposite end of the sleeve 22 abutting a shoulder 42 formed on the boss 38. A multiplicity of pins 43, one for each sprag body 28, 29, extends outwardly from the rear face of the handwheel 37 through respective arcuate slots 44 in the first plate member 12 to engage an arcuate slot 45, 46 in the sprag bodies 28, 29 respectively.The slots in the plate member 12 and in the sprag bodies 28, 29 are of similar arcuate extent but are of different radial dimension, the slots 45, 46 in the sprag bodies 28, 29 being of greater width to allow of unrestricted pivotal motion of such bodies 28, 29 on actuation of the adjustment means 14.

Furthermore, the slots 45, 46 in alternate sprag bodies 28 are laterally displaced in relation to those in the intermediate sprag bodies 29.

As is readily apparent from the drawings, which show the mechanism in a locked condition, the major axes of the alternate individual sprag bodies 28, 29 are inclined on opposite sides of the respective radial lines which pass through the individual pins 43 of such bodies, one set of such bodies serving to prevent relative rotation between the plate members 11, 12 in a first direction and the other set thereof preventing relative rotation in other direction.

Rotation of the handwheel 37 in a given direction will cause the pins 43 to move along the slots 45, 46 in the respective sprag bodies 28, 29 and in the first plate member, 11, alternate such pins 43 abutting the end of the slots 45 in the sprag bodies 28 with which they are respectively engaged to initiate rolling of such bodies 28 on the inner cylindrical surface 31 and out of engagement with the opposing such surface 32 before the same pins 43 abut the corresponding ends of the slots 44 in the first plate member.On abutment of the pins 43 with the ends of the relatevant ones of the slots 44 in the first plate member 11, which abutment occurs before the intermediate pins 43 engage the corresponding ends of the respective slots 46 in alternate sprag bodies 29, and continued rotation of the handwheel 37, the first plate member 11 is pivoted about the common axis of the first and second such members 11, 1 2.

On release of the adjustment means 14 the mechanism reverts to the condition illustrated in the drawings in which the seat back is locked in its adjusted position.

For adjustment in the reverse sense, the handwheel is rotated in the operative direction, and those sprag bodies which were simply idling or overrunning are now positively disengaged in analogous manner to that previously described.

It is believed that, by means of the mechanism hereinproposed I am able to provide a seat reclining mechanism of ready and reliable operation which will allow of the adjustment of a seat back to a high degree of accuracy and which will positively hold the seat back in an adjusted position.

Although the invention has been disclosed in relation to an embodiment providing for 360' of adjustment, in the context of vehicle seating a substantially lesser rnage of adjustment is necessary and it may be found convenient to provide a locking means of, say, 110 arcuate extent, with the structure illustrated being modified accordingly.

Whilst the primary application of the invention is in the context of vehicle seating, the mechanism is thought to be of application in any other context where accurate and reliable adjustment and locking of two angularly adjustable elements is required.

The invention is not restricted to the detail of the embodiment hereinbefore described, since alternatives will readily present themselves to one skilled in the art. Thus, the inner cylindrical surface of the annular space within which the locking means is located may be replaced by a contoured surface to provide a seating for the inner ends of the sprag bodies if preferred.

Claims (26)

1. An adjustment mechanism comprising two angularly adjustable, coaxially arranged members, for respective attachment to structures between which relative angular adjustment is required, releasable locking means between and selectively operably engageable with said members, and adjustment means engaged with one of said members and adapted to effect release of said locking means and angular movement of said one member relative to the other of said members upon actuation of said adjustment means.

2. An adjustment mechanism accordicng to claim 1 wherein said locking means includes an oppositely directed sprag clutch arrangement providing for controlled adjustment of the relative angular disposition of said members in each of two opposed directions.

3. An adjustment mechanism according to claim 1 or claim 2 wherein said adjustment means includes a lost motion mechanism providing that said locking means is released before relative angular movement between said member is initiated.

4. An adjustment mechanism according to any one of claims 1 to 3 wherein said members comprise plates in adjacent overlapping face-to-face disposition.

5. An adjustment mechanism according to claim 4 wherein each of said plates is of oval planform.

6. An adjustment mechanism according to claim 4 or claim 5 wherein each of said plates is of stepped configuration in longitudinal section.

7. An adjustment mechanism according to any one claims 4 to 6, wherein each of said plates has an aperture therein disposed centrally of a region thereof overlapped by the other of said plates, said apertures being mutually aligned.

8. An adjustment mechanism according to claim 7 wherein said one plate has an axially directed flange about the aperture therein.

9. An adjustment mechanism according to claim 8 wherein said other plate is dished about the aperture therein thereby providing an annular space between said plates coaxial with said apertures.

10. An adjustment mechanism according to claim 9 wherein said one plate includes a rib engaged by a corresponding groove provided in said other plate, said rib and groove being coaxial with said apertures.

11. An adjustment mechanism according to claim 10 wherein said plates are secured together by a sleeve engaged with said apertures.

1 2. An adjustment mechanism according to claim 11 wherein a radial flange is provided on said sleeve cooperating with an opposed lip provided on said axially directed flange on said one plate.

1 3. An adjustment mechanism according to claim 12 comprising a circip located in a groove provided in said sleeve and bearing against an outer face of said other plate.

14. An adjustment mechanism according to claim 1 2 or claim 1 3 comprising a bearing arrangement interposed between said radial flange and said opposing lip.

1 5. An adjustment mechanism according to claim 2 or any claim dependent thereon wherein said sprag clutch arrangement comprises two sprag clutches having respective elements thereof arranged alternately and in opposed disposition.

1 6. An adjustment mechanism according to claim 1 5 wherein each of said elements comprises a sprag body of oval form.

1 7. An adjustment mechanism according to claim 16 when dependent on claim 9 wherein each of said elements has a major dimension whereby said element may bridge said annular space between said plates.

1 8. An adjustment mechanism according to claim 1 7 comprising a pair of springs, which are disposed to bias each of said elements into engagement with an opposing axially directed cylindrical surface bounding said annular space.

1 9. An adjustment mechanism according to claim 1 9 wherein said springs engage lugs provided on and extending from each of said elements.

20. An adjustment mechanism according to claim 11 or any claim dependent thereon wherein said adjustment means comprises a handwheel having a central boss which extends through said sleeve.

21. An adjustment mechanism according to claim 20 when dependent on claim 1 5 wherein a plurality of pins are provided on and extend outwardly from said handwheel through respective arcuate slots provided in saidfirst member to engage an arcuate slot in a respective element.

22. An adjustment mechanism according to claim 21 wherein each arcuate slot provided in said first member is of similar arcuate extent as but of different radial dimension from the arcuate slot provided in the respective element.

23. An adjustment mechanism according to claim 22 wherein the arcuate slots in said elements are of larger radial dimension than the arcuate slots in said first member.

24. An adjustment mechanism according to claim 22 or claim 23 wherein the arcuate slots in alternate elements are laterally displaced from those in the intermediate ele ments.

25. An adjustment mechanism according to claim 1 7 or any claim dependent thereon wherein the major axes of alternate elements are oppositely inclined relative to the radial lines passing therethrough from the intermediate elements.

26. An adjustment mechanism substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.