GB2219933A

GB2219933A - Seat slide assembly characterised by the configuration of the interengaging members

Info

Publication number: GB2219933A
Application number: GB8814714A
Authority: GB
Inventors: Martin John Lusty
Original assignee: Lear Corp Nottingham Ltd
Current assignee: Lear Corp Nottingham Ltd
Priority date: 1988-06-21
Filing date: 1988-06-21
Publication date: 1989-12-28
Also published as: GB8814714D0; DE3920124A1; FR2632906A1

Description

2219933 SEAT SLIDE ASSEMBLY This invention relates to seat slide

assemblies for adjustable seats. The invention is particularly applicable to a seat slide assembly for a seat in a motor vehicle which is to be adjustable in the fore- and -aft direction.

Seat slide assemblies for. for example, motor vehicle seats comprise two principle members. one secured to the floor and the other secured to the seat, which are slideably mounted on one another. Commonly.

such seat slide assemblies are made of pressed or rolled steel. The seat belt anchorage is often fixed to the slide member secured to the seat in order to maintain the relative position of the anchorage with respect to the seat occupant. This is found desirable on an adjustable seat as the arrangement of the seat belt is not substantially disturbed by adjustment of the seat in relation to the body of a car.

The slideable members of such an assembly are constructed so that they engage one another and thus resist the parting force which will urge them out of their relative vertical positions when a vehicle is subjected to severe deceleration such as occurs in a collision.

Typically, a seat slide assembly will also be provided with a locking device which is arranged to restrain the members in a particular relative horizontal position corresponding to a desired seat position.

The load applied to the member of the assembly secured to the seat comesi,in the main, from the seat belt anchorage which restrains the body of the occupant. This force applied to the slide assembly can 2 be resolved into vertical and horizontal components. The horizontal component is resisted by the locking device which prevents the seat moving in the fore and after direction. The vertical force is resisted by the engaged slide members. The force on the slide members of an occupied seat is substantial.

Known pressed or rolled steel assemblies, however, suffer from a number of limitations inherent in their design and manufacture.

Firstly. the intricacy of the profiles of the engaging portions of the members are limited by the manufacturing process. Thus, the engaging members may be laterally deformed when they are subjected to high separation forces. The engaging portions,usually in the form of lips, tend to bend out of engagement so that the coupling between the members gives way before the maximum shear strength of the metal of the slide members is reached. Thus, the maximum potential strength of the slide member material is not utilised.

Secondly, in typical rolled or pressed seat slide assemblies the section of the member secured to the floor is not inherently adapted to be as rigid as is desirable to withstand the tendency of the floor mounted member to fail in bending. This tendency is most pronounced when the seat is adjusted so that the seat belt anchorage point is midway between points on. the floor member at which it is secured to the floor.

Thirdly, steel is a suitable material for known slide members in which it is the practice to rely upon the stiffness of the material to provide the requisite strength, as it is also suitably ductile for rollirj or pressing. However, the gauge of steel required to provide that stiffness also makes the seat slide 3 assembly relatively heavy. Furthermore, the thicker the gauge of the steel the more powerful must be the presses used to form the members.

According to the present invention a seat slide assembly comprises a first elongate slide member arranged to be secured with respect to a floor and a second elongate slide member mounted on the first slide member to slide longitudinally with respect thereto, the second slide member including a generally planar portion and two engaging formations which extend over substantially its entire length and engage a respective formation on the 'first slide member, each formation on the first and second slide members including a substantially U-shaped portion in transverse cross- section, the limbs of which extend transverse to the planar portion and define a channel which receives a limb of the formation with which it is in engagement. It is preferred that the shape of each channel is substantially the same as that of the limb which it receives.

Thus in the assembly in accordance with the present invention the shape of the two members is very much more complex than in known assemblies and provides a positive interlock which permits relative longitudinal sliding movement but more positively resists deformation and thus separation of the two members.

In the preferred embodiment the two members are manufactured by extrusion and comprise e.g. aluminium or aluminium alloy or another suitable light alloy. The use of extrusion permits the shape of the two members to be determined solely by strength considerations and not to be influenced by the 4 manufacturing method, as was the case in the previously known rolled or pressed steel constructions. This in turn permits the ultimate strength of the seat slide assembly in accordance with the invention to be determined primarily by the tensile strength of the material used and not by the shape or construction of the two members. The engaging formations may simply be of U-shape with their limbs substantially parallel and intersecting the base of the U substantially at right angles. However, more complex shapes are possible and the free end of the outer limb of each U may be connected to one or more further limbs inclined thereto. The limbs of the U need not intersect the base of the U at right angles but could do so at a different angle or at a radius.

In the preferred embodiment the first member is generally of box section defining a slot in its upper surface and a longitudinally extending internal cavity and the planar portion of the second member extends through the slot, the engaging formations on the second member being accommodated within the cavity.

In order to further stiffen the first member it is preferable to provide it with one or more stiffening ribs. The stiffening ribs may include Lshaped webs on the base of the first member which may define a cavity which is accessible through a longitudinal slot defined by opposing limbs of the webs. The provision of such a slot facilitates the connection of mountinr brackets.

Thus in the seat slide assembly in accordance with the present invention the formations on the first and second members are in effect hooked together. A separating force applied to the assembly which tends to deform the members must therefore overcome the inter- engagement of the formations before the members can be separated. However, due to their complex shape the formations become increasingly engaged as the separating force applied to them increases. It has been found that separation under impact loading does not occur in a seat slide assembly according to the invention until the limit of the shear strength of the material of the members has been reached. Consequently, the full potential of the strength of the material is utilised.

The present invention can be put into practice in various ways and one embodiment will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a side view of a seat slide assembly according to the present invention; FIGURE 2 is an end view of the assembly in Figure 1; and FIGURE 3 is a lateral section taken along the line 111-111 of Figure 1.

Referring to Figures 1 to 3, a seat slide assembly comprises an upper rail 10, slideably received in a lower guide rail 12. The assembly is normally mounted in a vehicle such that the rails extend in the longitudinal direction thereof. Although the assemblies would normally, but not necessarily, be used in pairs to support a vehicle seat, only one is shown here without the seat for the sake of clarity.

As best seen in Figures 1 and 2, a seat belt anchor plate 14 is bolted to the rear end (right-hand end, as shown in Figure 1) of the upper rail 10.

The lower rail 12 can be bolted to the floor of the vehicle through fore and aft holes 15 and 18, 6 respectively. The aft hole 18 is formed, in this embodiment, in an angle plate 20 secured to the lower rail 12.

The upper rail 10 rides on ball bearings 22 which travel in longitudinally extending pairs of laterally spaced ball races 24 and 26 formed in the rails 10 and 12.

The relative longitudinal position of the upper rail 10 with respect to the lower rail 12 is maintained in any one of a range of positions by means of a movable tooth plate 28 mounted on the end of a lever arm 30. The lever arm 30 is hingedly mounted on the upper rail 10 to bring the tooth plate into and out of engagement with complementary formations 32 on the lower rail 12. When the tooth plate 28 is engaged with the formations 32 the upper rail 10 is prevented from moving in a longitudinal direction. Clearly, it is not essential for the tooth plate and lever to be mounted on the upper rail, although this does not mean that it will move with the seat. It could equally well be mounted on the stationary lower rail and be arranged to engage formations on the upper rail.

With particular reference to Figure 3, the lower rail 12 has an extruded aluminium box section. The box section is formed with an upper longitudinally extending central slot 34 which opens into the interior of a cavity 36 defined by the box section. Each of the lower corners 38 of the internal surface of the box section define one of the pair of laterally spaced ball races 26 which each accommodate a set of the ball bearings 22.

The upper rail comprises an extruded aluminium closed box section plate 40 which is generally planar 7 and extends into the central slot 34 of the lower rail. The dimension of the box section in the direction of insertion into the slot 34 is less than the lateral dimension. The lower end of the plate 40 is formed with a pair of similar engaging formations 41 including oppositely laterally extending flanges 42. Each flange 42 is formed with an outer inwardly radiused portion constituting the pair of laterally spaced upper ball races 24. Each of the ball races 24 is diametrically opposite the corresponding ball race 26 in the box section. Thus, the weight of the seat mounted on the upper rail 10 is distributed evenly between the two sets of ball bearings 22, which in turn bear on the lower rail 12 secured to the floor of the vehicle.

Each of the flanges 42 extends laterally from the plate 40, i.e. substantially horizontally, and then upwardly from the ball races 24 and are then inwardly turned to define an engaging lug 44 which protrudes laterally towards the plate 40.

Similarly, the top portion of the box section of the lower rail 12, which defines the slot 34, comprises on each side, an engaging formation 45 including a downwardly extending flange 46 which terminates in a laterally outwardly extending engaging lug 48. Thus, it will be seen that the engaging lugs 44 and 48 co- operate by extending into a corresponding channel defined by the U-shaped section of the formations 41 and 45 to prevent the upper rail 10 from being removed vertically from the lower rail 12 through the slot 34.

The lugs 44 and 48 are a close fit within the said channels to the extent that the section of each lug is substantially complementary to that of the channel into which it is received. Situated between the lugs 48 and 8 the flanges 42 are elongate plastic strips 47 which ensure that these two components do not come into direct contact but can nevertheless slide satisfactorily relative to one another. The strips 47 are slightly curved across their width to provide a small amount'of pretensioning and ensure that they remain in contact with the lugs 48 and flanges 42.

The lower rail 12 is also formed with a pair of stiffening ribs 50 which extend laterally outwardly from its upper surface. The lower rail is further formed with a pair of laterally oppositely disposed lower stiffening ribs 52 which extend downwardly from beneath the box section. Each of the lower ribs is terminated in a horizontally extending foot plate 54 such that a slot is defined beneath the box section which allows access to the base thereof in order to allow fixing holes and/or latching apertures to be formed in the box section of the lower rail 12.

The purpose of the hollow plate 40 is to house upper attachment brackets, slide latching parts and/or a height adjustment mechanism for use in conjunction with the seat. The plate 40 can simply be cut as required in order to fix such auxiliary items.

In the event of a sudden deceleration of the vehicle, the occupant of the seat mounted on a pair of such seat slide assemblies will impose a sudden loading on the seat belt anchor plate 14. This load will be transmitted to the upper rail 10 which will tend to pull it out of engagement with the lower rail 12 secured to the vehicle floor. The engaging formations 41 and 45 will prevent this separation. In the worst cases the loading will distort the assembly and tend to pull the flanges 42 and 46 out of engagement. This 9 will result in deformation of the box section of the lower rail 12 such that the flanges 46 are urged upwardly and outwardly. Similarly, the flanges 42 on the upper rail 10 will be urged both outwardly and downwardly. However, deformation of all the flanges is resisted by their complex shape. By virtue of the mutual engagement of the engaging lugs 44 and 48 the separation of the two rails will be further resisted, after some distortion. by the increased engagement of the lugs due to that distortion. In effect, the flanges 42 and 46 become increasingly more jammed together with increasing distortion. Thus, resistance to the rails being separated is provided not only by the stiffness of the material but also by this inter- engagement of the engaging lugs which will prevent the lugs from becoming disengaged before the shear strength of the material is reached.

By constructing the rails with such inter-engaging lugs it is possible to rely more on the inherent shear strength of the material as opposed to its stiffness. Because of this it is possible to use extruded aluminium or light alloy as the material for the rails. The use of extrusion further allows the design of the sections of the rails to be considerably more complex than would be the case with rolled or pressed members. Thus, the shape of the inter-engaging sections is less constrained by the manufacturing process. The sections can therefore be designed to provide the maximum Section Modulus for a given size of rail in a single extruding process without need for a secondary strength _odification process to be carried out on the rail. The extrusion process also allows the rails to be formed with stiffening ribs as required. These can be in practically any desired shape or position, such as the lower ribs 52. The resulting T-slot in the base of the lower rail 12 allows lower attachment brackets to be located in appropriate apertures in the base of the box section then riveted or otherwise secured in place on the floor of the vehicle.

11

Claims

1. A seat slide assembly comprising a first elongate slide member arranged to be secured with respect to a floor and a second elongate slide member mounted on the first slide member to slide longitudinally with respect thereto. the second slide member including a generally planar portion and two engaging formations which extend over substantially its entire length and engage a respective formation on the first slide member, each formation on the first and second slide members including a substantially U-shaped portion in transverse cross-section, the limbs of which extend transversely to the planar portion and define a channel which receives a limb of the formation with which it is in engagement.

is

2. An assembly as claimed in claim 1.. wherein the shape of each channel is substantially the same as that of the limb which it receives.

3. An assembly as claimed in claim 1 or claim 2, wherein the first and second members are manufactured by extrusion.

4. An assembly as claimed in any one of the preceding claims, wherein the first and second members are made of aluminium or a light alloy.

5. An assembly as claimed in any of the preceding cla-ms, wherein the first member is of box section defining a slot in its upper surface and a longitudinally extending cavity and the planar portion 12 of the second member extends through the slot, the engaging formations on the second member being accommodated within the cavity.

6. An assembly as claimed in claim 5, wherein the slot is defined by part of the engaging formations on the first member.

7. An assembly as claimed in claim 5 or 6, wherei1 the planar portion of the second member is a longitudinally extending hollow plate.

8. An assembly as claimed in any one of the preceding claims. wherein ball bearings are arranged between the first and second members.

9. An assembly as claimed in claim 8 when dependent on claims 5,6 or 7, wherein the balls are received in two ball races defined between the two lower corners of the box section and portions of the engaging formations on the second member.

10. An assembly as claimed in any of the preceding claims, wherein the second member is formed with at least one longitudinally extending stiffening web.

11. An assembly as claimed in claim 10, wherein the first member is provided with a pair of laterally spaced L-section webs on the base of the first slide member.

12. An assembly as claimed in any of the preceding claims, wherein position locking means are mounted on 13 one of the first and second members, which means are movable from a first position. in which they engage the other of the first and second members to prevent relative longitudinal movement therebetween, and a second position in which relative movement is permitted.

13. An assembly as claimed in claim 12. wherein the locking means comprise a toothed plate which is arranged to engage complementary formations on the other member, when in the first position.

14. An adjustable seat slide assembly substantially as specifically described herein with reference to the accompanying drawings.

Published 1989 at The Patent Office. State House, 6671 Ib9h HoIIborn. LondonWC1R 4T?- Further copies maybe obtained from The Patent Office. Sales Branch, St Mary Cray. Orpington, Kent BF.5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1!87

14. An assembly as claimed in any one of the preceding claims including an elongate plastics strip disposed between and contacting two adjacent limbs of the Ushaped portions of each cooperating pair of engaging formations.

15. An adjustable vehicle seat assembly comprising a seat mounted on a pair of laterally spaced seat slide assemblies as claimed in any of the preceding claims.

16. An adjustable seat slide assembly substantially as specifically described herein with reference to the accompanying drawings.

1, Amendments to the claims have been filed as follows 1. A seat slide assembly comprising a first elongate Q; slide member of box section which defines a slot in its upper surface and alongitudinally extending cavity and is arranged to be secured with respect to a floor and a second elongate slide member mounted on the first slide member to slide longitudinally with respect thereto, the second slide member including a generally planar portion which extends through the slot and two engaging formations which extend over substantially its entire length within the cavity and engage a respective formation on the first slide member, the first and second members being manufactured by extrusion and each formation on the first and second slide members including a substantially U-shaped portion in transverse cross-section, the limbs of which extend transversely to the planar portion and define a channel which receives a limb of the formation with which it is in engagement.

2. An assembly as claimed in claim 1, wherein the shape of each channel is substantially the same as that of the limb which it receives.

3. An assembly as claimed in claim 1 or claim 2, wherein the first and second members are made of aluminium or a light alloy.

4. An assembly as claimed in any one of the preceding claims, wherein the slot is"defined by part of the engaging formations on the first member.

5. An assembly as claimed in any one of the preceding claims, wherein the planar portion of the second member is a longitudinally extending hollow plate.

6. An assembly as blaimed in any one of the preceding claims, wherein ball bearings are arranged between the first and second members.

7. An assembly as claimed in claim 6, wherein the balls are received in two ball races defined between the two lower corners of the box section and portions of the engaging formations on the second member.

8. An assembly as claimed in any one of the preceding claims, wherein the first member is formed with at least one longitudinally extending stiffening web.

9. An assembly as claimed in claim 8, wherein the first member is provided with a pair of laterally spaced L-section webs on the base of the first slide member.

10. An assembly as claimed in any one of the preceding claims, wherein position locking means are mounted on one of the first and second members, which means are movable from a first position, in which they engage the other of the first and second members to prevent relative longitudinal movement therebetwedn, and a second position in which relative movement is permitted.

11. An assembly as claimed in claim 10, wherein the locking means comprise a toothed plate which is 16 arranged to engage complementary formations on the other member, when in the first position.

12. An assembly as claimed in any one of the preceding claims including an' elongate plastics strip disposed between and contacting two adjacent limbs of the Ushaped portions of each cooperating pair of engaging formations.

13. An adjustable vehicle seat assembly comprising a seat mounted on a pair of laterally spaced seat slide assemblies as claimed in any of the preceding claims.