WO1999005000A1

WO1999005000A1 - Method and apparatus for automotive seat position adjustment and locking

Info

Publication number: WO1999005000A1
Application number: PCT/GB1998/002107
Authority: WO
Inventors: Hugh Charles Christopher
Original assignee: Lear Corporation
Priority date: 1997-07-25
Filing date: 1998-07-27
Publication date: 1999-02-04

Abstract

An automotive seat adjustment and locking mechanism provides a rack (217) and pinion (229) seat track assembly (100) in which stepless position-adjustment is provided by rotary drive to the pinions either manually or by means of drive. The manual drive incorporates a stepless mechanical lock (210) for defining a seat-adjusted position. The pinion (220) of the seat track assembly is of ring format and has a roller-type locking mechanism (224) at its inner periphery (222) which is releasable by a lever mechanism (238, 240). This locking mechanism is located between the side plates (112, 114) of the seat slide as an integral part of the slide whereby strength is greatly increased. Similar locking facilities may be provided for backrest rake and seat height. Embodiments use a spring lock (228, 230) and a roller lock (224, 226). In one embodiment under overload (impact) conditions a shear pin in the drive allows tha rack and pinion ring gear to shift causing pivoted locking arms to move to locking positions thereby taking over the locking function and avoiding the need for massive strength in the drive train.

Description

METHOD AND APPARATUS FOR AUTOMOTIVE SEAT POSITION ADJUSTMENT AND LOCKING

This invention relates to a method and apparatus for automotive seat position adjustment and locking. Certain aspects of the invention provide for a new system for improving the means whereby an automotive seat is locked in position under conditions occurring during overload, such as vehicle impact. Other aspects of the invention relate to the provision of improved means for position- adjusting an automotive seat with respect to its track according to the requirements of the seat user, such provision seeking to offer improvements in relation to the means provided for position-adjustment and/or the cost- effectiveness of same and/or otherwise in relation to such systems.

In the case of automotive seat adjustment mechanisms in which a seat support structure adapted to receive an automotive seat is provided with track means whereby the seat can be position-adjusted lengthwise of the track, there is a need to provide a variety of functions including simple seat adjustment, effective seat locking in a chosen adjusted position, ability to withstand the overload conditions occurring upon vehicle impact, amongst other things, and these functions need to be provided in a cost-effective manner of course.

Previous systems providing some of these functions have included tracks provided with releasable peg and slot mechanisms and tracks having roller mechanisms, amongst others. These option leave something to be desired in terms of providing an adequate compromise between the various factors discussed above. Thus, the peg and slot mechanisms provide robust mechanical engagement offering satisfactory mechanical position-definition and overload resistance, but are often inconvenient to operate and in any case do not provide for stepless position-adjustment which leads to user dissatisfaction and other shortcomings. Roller-type seat track mechanisms offer stepless position adjustment but leave shortcomings in terms of robust seat position definition and ability to accommodate overload conditions. Generally, seat position-adjusting mechanisms offering power control are subject to limitations in order to withstand overload conditions, and the drive has to be built in an extremely substantial format which introduces cost factors which would be much better eliminated. Generally therefore there is a need for improvements in the areas discussed above, notably in relation to the provision of means whereby the usual seat position adjustments mechanism is able to accommodate the forces encountered during overload and/or means is provided whereby stepless adjustment of seat position can be achieved in a simple manner without the need for the substantial additional structure of locking mechanisms as has been a requirement for roller-type seat track mechanisms in the past, in order to provide the necessary structural integrity, and/or the provision of improvements generally in these areas. An object of the present invention is to provide improvements in relation to one or more of these matters, or improvements generally in this field. According to the invention there is provided a method and apparatus for automotive seat adjustment and/or locking as defined in the accompanying claims.

There is disclosed in US 4,648,656 (Kimura) a car seat in which a seat cushion frame has a rack and pinion device with a lock mechanism comprising (Figs 3 to 5) latch catches 26a, 26b co-operating with a gear 20a in a stepped manner at stepped intervals corresponding to the pitch of the gear teeth on gear 20a.

In the embodiments of the present invention the shortcoming of the use of a tooth-defined stepped adjustment mechanism is overcome by the provision of a stepless rotation-inhibiting or locking mechanism employing gripping means such as roller or ball or spring means which is adapted to grip a smoothly curved surface such as the inner surface of the ring-format pinion of the rack-and-pinion mechanism in the embodiments. In this way the user has the relative comfort and luxury of avoiding the discomfort of sensing that the mechanical definition of the adjusted seat position is achieved by a metal-to-metal toothed catch mechanism which, at best, defines the selected position by causing metallic catches to drop into the spaces between successive teeth on a gear pinion.

In contrast, the embodiments of the present invention define the users position by the use of rotationally-actuated devices of the roller or ball or spring kind which provide a stepless definition of the adjusted position at any location on the curved surface with which they coact. More over, these devices have an inherent self-servo effect.

In one embodiment described below, there is provided an integrated mechanism whereby position control of at least one of fore/aft seat adjustment and seat height adjustment and seat rake adjustment is provided. Thus, in one embodiment described below there is provided an automotive seat track assembly wherein at least one lockable rotary adjustment control member provides position control of at least one of : fore/aft adjustment seat height adjustment seat rake adjustment while said adjustment control member forms part of the seat track assembly. Indeed, in the embodiment, the adjustment member is mounted between the spaced side plates of a generally upright slide member of the seat track assembly. As a result, the rotary adjustment control member is easily and cost-e fectively incorporated into the seat track assembly at the time of original manufacture and has a relatively small impact on the cost /05000

-4- of the assembly as original equipment. Usually, the provision of a function such as continous adjustment of the seat fore/aft position is provided as an add-on function which has a significant impact on the overall cost of the seat track assembly. By the step of providing a mechanism which has such neglible space requirements that it can be incorporated into the seat track assembly as an intergral part thereof, the facility is provided of meeting the cost-effectiveness objective discussed above, very much more readily.

Likewise, as regards the mechanical effectiveness and strength objectives of the mechanism, these are also more readily met by a mechanism which can be incorporated as an intergral part of the seat track assembly because such an arrangement has an inherent strength and integrity which can never be matched by an add-on mechanism.

Further significant advantages arise from the fact that the adjustment mechanism is by no means limited to seat fore/aft adjustment, but is likely to be capable of providing for seat height adjustment and seat rake or angle adjustment not only in relation to the seat back but also the seat cushion. In these latter adjustment regards the principle of operation is as follows. In the same way that the rotary adjustment control member can provide (by virtue of being provided with a pinion format for cooperation with a corresponding rack) for seat adjustment lengthwise of the seat tracks, so also similar rotary adjustment control members can be provided to control seat height (through a cranked shaft) and seat rake. These latter functions can be controlled by means of an angular motion control device, and this is exactly what the rotary adjustment control member offers. Therefore, where one or both of these additional functions is required, all that is required is to provide the seat track assembly with one or two additional adjustment control members, mounted in a similar way to the control member for seat fore/aft adjustment, and to couple the relevant mechanisms to this or these. Since the two or three mechanisms do not need to interact directly, the invention allows any one or two or three of the mechanisms to be provided on the seat track assembly according to choice. As regards the space requirements for the provision of these one, two or three mechanisms, the position is as follows. Usually, the corresponding rotary adjustment control members will be provided at different locations on the seat track assembly, namely at the front (height adjustment) and in the middle region (fore/aft adjustment) and at the rear (seat rake adjustment) . Therefore, space considerations do not impede the simultaneous use of all three functions.

As regards the locking mechanism to be employed, in the embodiment this is provided by a roller mechanism in which pairs of spring-separated rollers coact with an inner diameter of the rotary adjustment control member and with an inner non-rotatable structure including an inner fixed lock plate non-rotatably connected to the seat slide. Other locking mechanisms may be employed.

Release of the locking mechanism is provided by means of pairs of pivotally connected release arms which are located on the outer side of the seat slide side plates and have release spigots extending inwards through arcuate slots in the side plates to coact with the rollers to release the locking mechanism. A cable assembly is provided to actuate the release arms for this purpose.

Also in the embodiments, a shear pin mechanism is provided connecting the release arms to the lock plate to enable an overload release function to be provided.

In an embodiment of another aspect of the invention the locking means for an automotive seat comprises primary and secondary locking mechanisms. The primary locking mechanism includes shear means adapted to shear under overload conditions, and the secondary locking mechanism is adapted to provide a secondary locking function which takes over from the primary locking mechanism under overload conditions. In this way the advantage is provided that the primary locking mechanism can be constructed in relatively insubstantial format in accordance with the requirements of everyday usage, and without the need to be constructed so as to be capable of withstanding overload conditions. The strength for withstanding overload conditions is provided by the secondary locking mechanism. This latter mechanism is provided in the format of a simple locking device which engages with the rotary seat position adjustment mechanism so as to lock same. In this way, the need for providing a very substantial and strong rotary drive to the seat is avoided. Most of the components in the rotary drive to the seat are subjected only to the loads arising in normal everyday use.

There is disclosed in US-A-5 076 529 (Dove) a seat adjuster with improved crash resistance. The seat adjuster comprises two adjustable track assemblies comprising latching plates and cooperating latching windows for manual control for vehicle seat adjustment purposes. As stated in this reference, in the case of a latch-type mechanism of this kind, if a vehicle should happen to be involved in a frontal crash, the load applied to the upper portions of the tracks tends to cause the latches to pivot to their unlatched positions. If the latch is released during a crash, forward movement of the seat is unrestrained and thus the passenger is more likely to incur a serious injury. The reference discloses a system in which in the event of a frontal crash, a weakened area deforms to enable a mounting bracket to move forwardly relative to the latch and to clamp the latch in its latched position, thereby preventing the latch from pivoting to its unlatched position.

Such an arrangement is directed specifically to solving a problem arising directly from the inherent nature of the latching mechanism concerned, and does not particularly assist in dealing with the question of the provision of a sufficiently strong drive transmission in a driven seat adjustment mechanism to enable the loads arising under overload to be withstood in an economical manner. A further feature of the described embodiment resides in the provision of a rack and pinion drive to the seat. The rack and pinion are in permanent constant-mesh engagement whereby stepless position adjustment is provided and the mechanical engagement between the components provides robust position definition in a stepless manner.

A drive to the pinion of the rack and pinion is provided by a complementary constant mesh pinion positioned to engage a ring of internal drive teeth on the annular-format main pinion, whereby a manual or electric drive to this complementary pinion can conveniently offer a low ratio position-adjusting facility whereby a vehicle driver can readily wind forwards or backwards the driver's or passenger's seat position with minimum manual effort. In the embodiment also, the manual control member not only offers a facility to drive the complementary pinion which engages the main annular rack-engaging pinion, but also is provided with a stepless spring-type locking clutch so that upon reaching a chosen seat position the user can readily fix the seat in the chosen position at which the friction clutch serves to transmit from the rack and pinion mechanism to a non-rotatable structure the resultant relatively high ratio drive, thereby effectively locking the plate in position. The rack and pinion drive system offers the additional advantage of providing a convenient means for the take-over function offered by the secondary locking mechanism. In the embodiment, the annular main pinion of the rack and pinion device is mounted for rotation by means of a plastic guide ring engaging the teeth or the like formed at its inner periphery and extending around that periphery as far as possible while leaving just sufficient room for the complementary pinion which is in permanent mesh with those teeth. A pair of shear pins mount the plastic guide ring on an adjacent non-rotatable structure. The result of this construction is that when the primary locking mechanism (provided by the clutch and the complementary pinion etc) is loaded under normal everyday conditions, the annular pinion of the rack and pinion resists the resultant forces (such as occur during normal vehicle braking) and the seat remains in its adjusted position. Under overload conditions, the loads applied to the ring gear (which has no bearings of its own) and which are therefore resisted solely by the plastic guide ring, are sufficient to cause the shear pins to shear. When this happens, the annular pinion gear rotates not about its own normal operating axis but around its tooth engagement point with the complementary pinion gear thereby causing bodily movements and serving to actuate a locking arm which moves to a locking position in engagement with the outer teeth of the ring gear. It can thus be seen that the general arrangement is such that when overload occurs, a component in the drive frame is caused to move about an axis differing from the axis about which it moves under non-overload conditions, thereby actuating the take-over system of the secondary locking mechanism.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figs 1 and 2 are taken from our US patent 5,020,853 showing details of an automotive seat track assembly of the kind to which the present invention is applicable; and Fig 3 shows on a larger scale a side elevation view of a lockable rotary adjustment control member for use in the seat track assembly of Figs 1 and 2 ; Figs 4 and 5 show perspective and side elevation views of a further development of the embodiment of Fig 3; Fig 6 shows a side elevation view of a portion of an automotive seat adjustment and locking mechanism as viewed generally in a direction transverse to the lengthwise extent of the seat track and axially of the seat drive mechanism;

Fig 7 shows the mechanism of Fig 6 with the additional indication of other components, notably including a tri-lobed handwheel device for actuating the seat adjustment and locking mechanism; and Fig 8 shows a section through the mechanism of Fig

6_. generally on the line VIII-VIII in Fig 6, and showing details of the construction of the seat track and the manual operating knob.

We hereby incorporate into the present application the entire description of our above-mentioned US 853 patent and its accompanying drawings.

For the purposes of the present application, we mention that the seat track assembly 100 comprises main components including pairs of fixed lengthwise tracks 102 on which a seat slide 104 is mounted for lengthwise adjustment through ball races 106.

An adjustable rake seat back 108 is shown in Fig 1. Fig 3 shows the lockable rotary adjustment control member 110, and this is mounted within track assembly 100 and between the side plates 112, 114 for rotary cooperation of its teeth 116 with a rack provided in the base 118 of each track 102.

In a practical embodiment, the side plates 112, 114 will be spaced apart to a greater extent in the upward direction than is shown in Fig 2 in order to provide additional space to accommodate control member 110.

Turning to Fig 3, the lockable rotary adjustment control member 110 comprises an outer toothed portion 120 formed with teeth 116 and having an inner diameter 122 within which pairs of locking rollers 124, 126 are located and urged apart by springs 128, 130 located within arcuate slots 132, 134 formed in a fixed lockplate 136. Release arms 138, 140 are provided at 142 for actuation by a control cable and sheath (not shown) connected between one of the pairs of arm ends. Release spigots 144 at the arm ends project through arcuate slots in side plates 112, 114 of the seat slide 104 to engage rollers 124, 126 for release purposes.

The mode of operation of the device is as follows.

Locking of the rotary adjustment control member 110, in the form of a ring gear, is effected by pairs of locking rollers 124, 126 under the action of springs 128 at all times except when release arms 138, 140 are actuated to cause movement of the rollers towards each other against the action of the springs. Such movement is under the control of a cable mechanism (not shown) actuated by the user. In this way, stepless position adjustment of the seat is available by mere actuation of the cable and the user can readily slide his/her seat manually or otherwise.

Turning now to the modification shown in Figs 4 and

5, of the preceding embodiment, this will now be described utilising reference numerals related to those used in the preceding embodiment. Where the corresponding parts are the same ones or substantially identical, the same reference numerals are used. Where the parts simply correspond to those of the preceding embodiment, the same reference numeral is used, but increased by 100 (so as to lie in the range 200 to 300) .

Thus, as shown in Figs 4 and 5, seat track assembly 100 comprises fixed lengthwise tracks 102 on which seat slide 104 is mounted for lengthwise adjustment through ball races.

A lockable rotary adjustment control member 210 is mounted within track assembly 100 and between its side plates 112, 114 for rotary co-operation of its teeth 216 with a rack 217 provided in the base 218 of each track 102.

In this practical embodiment, the side plates 112, 114 are spaced apart by the distance D in order to accommodate control member 210.

The lockable rotary adjustment control member 210 is in the form of a toothed pinion having an outer toothed portion 220 formed with the teeth 216, and having an inner diameter 222 within which pairs of locking rollers 224 and 226 are located and urged apart by springs 228, 230 located within slots 232, 234 formed in a fixed lockplate 236 on which annular pinion 220 is journaled for rotation. Lockplate 236 is fixedly mounted between side plates 112, 114 and provides a circular outer bearing surface which co-operates with the corresponding edge surface at inner diameter 222 of the pinion 220.

Release arms 238, 240 are pivoted at central axis 242 for actuation by a control cable 243 acting between flanged ends 246, 248 of the arms. The release arms 238, 240 have formed end portions 244 which are positioned and disposed so as to actuate the rollers 224, 226 by displacing the roller pairs towards each other against the resilient resistance of springs 228, 230 in order to release the rollers from their normal locking position. Use of the embodiment of Figs 4 and 5 proceeds substantially as described above in relation to Figs 1 to 3.

Turning now to embodiment of Figs 6 , 7 and 8 , this differs from the preceding embodiments in that the locking and control mechanism is not located integrally within the sliding portion of the seat track assembly, but in an exterior manner permitting manual rotation of the pinion for position adjustment purposes. As shown in Figs 6, 7 and 8 of the drawings, an automotive seat adjustment mechanism 310 comprises seat support means 312 adapted to support a seat for a vehicle driver or passenger (not shown) , the seat support means comprising seat track means 314 having rotary seat support elements 316 engageable with a track 318 and permitting stepless position-adjusting movement of a seat (not shown) mounted on the support means 312 for movement lengthwise of the track and permitting stepless locking of the seat in an adjusted position by actuation of locking means 320 associated with the rotary seat support element 316.

The seat track means 314 comprises rack and pinion means 322 including a rack 324 adapted to be fixedly mounted on a vehicle body and a pinion 326 connected to the seat support means 312 whereby the rack and pinion means 322 permits stepless adjustment of the seat with respect to the track. Rotation inhibiting or locking means 328 is provided for pinion 326 so that the vehicle seat can be stopped and held in selected ones of the available steplessly adjustable positions. The rotation inhibiting means comprises clutch means 330 connected to pinion 326 through a step-up (velocity ratio increasing) drive to a relatively non-rotatable structure 332. For this purpose, pinion gear 326 is in the form of a ring gear formed with drive teeth 334 at its inner periphery 336 and which drivingly engages a complementary smaller pinion 338 through clutch means 330 to non-rotationable structure 332.

Clutch means 330 comprises a manually-operable friction clutch 340 in the form of a coiled spring clutch device adapted to be actuated by a tri-lobed knob 342 to provide the alternative functions of stepless clutching the drive from pinion 326 to non-rotatable structure 332, and of permitting manual drive to be applied to knob 342 and clutch means 330 and thus to the smaller pinion 338 to effect stepless position-adjustment of the vehicle seat (not shown) .

Turning now more particularly to the locking systems for the seat adjustment mechanism, locking means 320 comprises primary 344 and secondary 346 locking mechanisms of which the primary mechanism 344 comprises shear means 348 including shear pin 350 adapted to shear under overload conditions. The secondary locking mechanism is adapted to provide a secondary locking function which takes over from the primary locking mechanism under overload conditions.

Shear pins 350 in the drive train to the non- rotatable structure 332 provide the shear function. Pivoted locking arms 352, 354 are adapted to move from their indicated non-locking positions to locking positions upon overload conditions occurring. When overload occurs and shear pins 350 shear, annular pinion 326 moves about its point of engagement with complementary pinion 338 and moves ring gear 326 into engagement with one or other of the locking arms 352, 354, thereby actuating same and causing it to exert its locking function.

It is believed that the main functionality of the mechanism will be clear in view of the above description. Further features of the mechanism shown in the drawings include the following. Firstly track means 314 comprises slidingly inter-engageable upper 356 and lower 358 tracks. The upper track 356 is constructed with suitable formations for attachment of a seat directly thereto. Of course, the seat is supported on a pair of seat support means 312, one for each of a pair of spaced fore and aft extending tracks. These are linked by a cross shaft 360 having a pinion 362 in constant mesh at each end with the complementary pinions 338 which mesh with the annular pinion 326 of the rack and pinion means 322. The sliding inter-engagability of the upper and lower tracks 356,358 is provided by means of ball races 364. Further details of the general structure of the upper and lower tracks may be obtained from our prior patent EP-B-0076041 (Ref 01242GB) .

The general construction of clutch means 330 comprises a spring assembly within a drum 364 and providing a rotationally-operable selectively available stepless clutch and drive function about the axis 66 of control knob/handle 342 and of the complementary smaller pinion 338.

Considerable variation in the detailed structure of the embodiment is within the competence of the person skilled in the art including the provision of alternative clutch means, the provision of an electric or other drive, modified shear member arrangements, alternative track designs and the like.

Claims

1 An automotive seat adjustment mechanism comprising: a) seat support means adapted to support a seat for a vehicle driver or passenger; b) said seat support means comprising seat track means having rotary support elements engageable with a track and permitting fixed position-adjusting movement of a seat mounted on said track for movement lengthwise of said track and permitting locking of such seat in an adjusted position by actuation of locking means associated with said rotary seat support elements; c) said seat track means comprising rack and pinion means including rack means adapted to be fixedly mounted on a vehicle body and pinion means connectible to said seat support means whereby said rack and pinion means permits stepless adjustment of said position of a seat mounted on said seat support means with respect to said track; and d) rotation-inhibiting or locking means for said pinion relative to said rack whereby said seat support means can be stopped and held in selected ones of said steplessly adjustable positions with the engagement of the meshing teeth of said rack and pinion providing direct mechanical position definition without requiring subsidiary locking means acting between said rotary seat support elements and said track; characterised by e) said rotation inhibiting or locking means comprises stepless rotation inhibiting means whereby said seat support means can be steplessly stopped and steplessly held in said selected ones of said steplessly adjustable positions. 2 An automotive seat adjustment mechanism characterised by rotation inhibiting means for a pinion of a rack and pinion mechanism of seat track means whereby a seat can be stopped and held in selected ones of the steplessly adjusted positions provided by said rack and pinion, with the engagement of the meshing teeth of said rack and pinion providing direct mechanical position definition without requiring subsidiary locking means acting between the rotary seat support elements and the track.

3 An adjustment mechanism according to claim 1 or claim 2 characterised by said rotation inhibiting or locking means being selected from the group comprising roller means, ball means, and spring means adapted to engage and grip a smoothly curved surface.

4 An adjustment mechanism according to claim 3 characterised by said locking mechanism comprising resiliently actuated rollers releasable by a lever mechanism.

5 An adjustment mechanism according to any one of preceding claims characterised by said rotation inhibiting or locking means being adapted to engage directly an inner surface of a ring-form pinion of said rack and pinion mechanism.

6 An adjustment mechanism according to any one of the preceding claims characterised by said locking means being mounted on a movable slide member of a seat track assembly and between side plates thereof.

7 An adjustment mechanism according to claim 6 characterised by at least one further similar locking mechanism mounted between said side plates to control adjustment of at least one other feature of said seat. 8 An adjustment mechanism according to any one of the preceding claims characterised by said rotation inhibiting or locking means comprising clutch means actuatable to connect said pinion through a step up (velocity ratio increasing) drive to a relatively non- rotatable structure.

9 A seat adjustment mechanism according to claim 8 characterised by said step up drive from said pinion to said relatively non-rotatable structure comprising providing said pinion as a ring gear formed with drive teeth at its inner periphery which drivingly engage a complementary smaller pinion coupled through said clutch means to said non-rotatable structure.

10 A seat adjustment mechanism according to claim 8 or claim 9 characterised by said clutch means comprising a manually operable friction clutch adapted to be actuated to provide alternative functions of clutching said drive to said relatively non-rotatable structure and of permitting manual drive to be applied to said clutch and to said complementary pinion to effect said stepless adjustment of said seat support member with respect to said track.

11 An automotive seat adjustment mechanism comprising: a) seat support means adapted to support a seat for a vehicle driver or passenger; b) said seat support means comprising seat track means having seat support elements engageable with a track and permitting position-adjusting movement of a seat mounted on said seat support means for movement lengthwise of said track and permitting locking of such seat in an adjusted position by actuation of locking means associated with said seat support elements; characterised by c) said locking means comprising primary and secondary locking mechanisms, said primary locking mechanism including shear means adapted to shear under overload conditions, and said secondary locking mechanism being adapted to provide a secondary locking function which takes over from said primary locking mechanism under overload conditions.

12 An automotive seat adjustment mechanism characterised by locking means for a seat on a seat track including primary and secondary locking mechanisms, said primary locking mechanism including shear means and said secondary locking mechanism being adapted to take over from said primary locking mechanism under overload conditions.

13 A seat adjustment mechanism according to claim 1.1 or claim 12 characterised by said primary locking mechanism comprising a shear pin associated with a drive train to a rotary drive member for a vehicle seat to be mounted on said seat adjustment mechanism.

14 A seat adjustment mechanism according to any one of claims 11 to 13 characterised by said secondary locking mechanism comprising a pivoted locking arm adapted to move from a non-locking to a locking position upon overload conditions occurrence.

15 A seat adjustment mechanism according to claim 14 when dependent upon claim 13 characterised by said shear pin being arranged to cause said drive train itself to engage said pivoted locking arm and to cause said locking arm to move to its locking position. /05000

19

16 A method of adjusting an automotive seat with respect to a seat track characterised by providing primary and secondary locking mechanisms for said seat with respect to said track and causing shear means of said primary locking mechanism to shear under overload conditions and causing said secondary locking mechanism to take over from said primary locking mechanism with a secondary locking function under such overload conditions.

17 A method of adjusting an automotive seat with respect to a seat track therefor, comprising providing a rack and pinion mounting for said seat and causing said seat to be steplessly locked in an adjusted position by means of rotation inhibiting means for said pinion.

18 An automotive seat track assembly wherein at least one lockable rotary adjustment control member provides position-control of at least one of : fore/aft adjustment seat height adjustment seat rake adjustment and forms part of the seat track assembly.

19 An automotive seat track assembly wherein a lockable rotary adjustment control member provides seat position control while forming part of the seat track assembly.

20 The seat track assembly of claim 18 or claim 19 characterised by said rotary adjustment control member being rotatably mounted on an upright slide member of said seat track assembly and between side plates thereof. 21 The automotive seat track assembly of claim 20 characterised by said rotary adjustment control member comprising a pinion of a rack-and-pinion assembly with said rack comprising part of the track portion of the seat track assembly.

22 The seat track assembly of any one of claims 18 to 21 wherein said locking mechanism comprises spring- actuated rollers releasable by a lever mechanism.

23 A method of automotive seat adjustment comprising providing an automotive seat track assembly with at least one lockable rotary adjustment control member and the method comprising controlling the angular movement of said adjustment control member to effect continuous adjustment of at least one of : fore/aft adjustment seat height adjustment seat rake adjustment while said rotary adjustment control member forms part of said seat track assembly.