GB2035792A

GB2035792A - Webbing for seats

Info

Publication number: GB2035792A
Application number: GB7846863A
Authority: GB
Original assignee: Chrysler United Kingdom Ltd
Current assignee: Peugeot Motor Co PLC
Priority date: 1978-12-01
Filing date: 1978-12-01
Publication date: 1980-06-25
Also published as: GB2035792B

Abstract

A seat back rest comprises a frame (11) having resilient webbing stretched thereacross for supporting upholstery, and a device (26, 34) for adjusting the tension of the webbing (17) intended to support the lumbar region of a user's back. The device (26, 34) comprises a lever (26) which is pivotally mounted in a mounting element (12, 19) welded to and extending rearwardly of the frame (11) and of which one arm (29) is connected to the webbing (17) of which the tension is to be adjusted. The other arm (32) of the lever is engaged by a threaded rod (34) engaged in a threaded bore (24a) in the mounting element (12, 19) and spaced rearwardly of the front surface of the frame (11). Movement of the rod (34), due to rotation thereof, laterally inwardly or outwardly of the frame (11) causes the lever (26) to pivot and is thus transmitted by the lever (26) to the webbing (17) respectively to increase or decrease the tension thereof. <IMAGE>

Description

SPECIFICATION Improvements in or relating to seats The invention is related to improvements in or relating to seats, and particularly to a back rest for a seat comprising a frame and resilient webbing which extends between the sides of the frame, and incorporating means for adjusting the tension of at least that part of the webbing which is intended to support the lumbar region of the back of an occupant of the seat, hereinafter called the "lumbar support region of the webbing". Usually, the webbing serves as a support for upholstery.

Seats having back rests of this type are particularly, but not exclusively appropriate for use in automobiles or other vehicles in which correct support of an occupant's back is desired.

The tension of the webbing in the lumbar support region is conveniently adjusted by the application to the webbing of a force having a line of action orientated substantially in the plane of the webbing and perpendicular to the longitudinal direction of the sides of the back rest frame between which the webbing extends. Previous proposals for devices capable of exerting such a force at one side of the frame, such as those disclosed in British Patent Specifications Nos 360516 and 1077189, involve a threaded rod which passes through a hole in the back rest frame, a connector to which the webbing at that side of the frame is secured and a direct threaded connection between the connector and the rod such that rotation of the rod in said hole with respect to the frame by, for example, a hand hold on the end of the rod, moves the connector via the threaded connection towards or away from that side of the frame and thereby stretches or relaxes the webbing. Such devices may be provided at either or both sides of the frame.

According to the present invention, there is provided a seat back rest comprising a frame; resilient webbing connected to and extending across the frame; and a tension adjusting device carried by one side member of the frame for adjusting the tension of at least the lumbar support region of the webbing by the application thereto of a force of which the line of action is orientated substantially in the plane of the webbing adjacent the frame side member and substantially perpendicular to the longitudinal direction of the frame side member, said device comprising a mounting element which is secured to the frame side member and which has formed therein a threaded bore of which the axis is substantially parallel to and spaced from the line of action of said applied force, a threaded rod which is threadably engaged within the bore, a lever which is pivotally mounted on the mounting element with one arm of the lever operatively engaged by one end of the threaded rod, the other arm of the lever being connected to the webbing adjacent said frame side member whereby movement of the threaded rod along the axis of said bore inwardly or outwardly of the frame due to rotation of the rod causes the lever to pivot and thereby to apply said force to said webbing respectively to increase or decrease the tension thereof.

The provision of the threaded bore accommodating the threaded rod in the mounting element, which is secured to the frame side member by, for example, welding, means that the inherent strength of the frame is greater than if the bore hole were to be provided in the tubular frame side member itself, as described for example in the above mentioned British Patent Specification No 1077189.

Moreover, the use of a pivoted lever to transmit the movement of the threaded rod to the webbing to apply the necessary force thereto enables the rod to be located rearwardly of the front face of the back rest frame so that a handwheel preferably mounted on the other, outer end of the rod for use in rotating the rod need not protrude beyond the surface of any upholstery which may be provided on the back rest frame. More importantly, however, the use of the lever enables the rod to be located at a position in which a handwheel mounted thereon can be conveniently rotated by an occupant of a seat of which the back rest is a part, a position not always to be found adjacent the lumbar support region of the webbing.

The lever may be arranged so that its plane of rotation may be orientated at an angle to the longitudinal direction of the frame side member within a wide range of angles which aids the convenient positioning of the threaded rod to facilitate ease of access to a handwheel mounted thereon.

The simplicity of the construction of the tension adjusting device incorporated in the present invention means that the invention can be applied to existing seat back rest constructions having webbing extending over a frame with a minimum of modification required to the existing construction.

Reference is now made to the accompanying drawings which illustrate, by way of example, one embodiment of the present invention, and of which: Figure 1 is a perspective view of part of a vehicle seat back rest according to the invention; Figure 2 is a part-exploded part-cut-away perspective view on a larger scale of part of the back rest shown in Fig. 1; and Figure 3 is a view along the line 3-3 in Fig. 1.

Referring to Fig. 1 of the drawings, there is shown part of a vehicle seat back rest frame 10 comprising an inverted U-shape metal tube 11. On each limb of the tube at the lower end thereof is welded the front edge of a metal plate 12, the rear edge of the plate 1 2 being welded to the lower end of a Usection support member or strut 1 3. The upper end of the support strut is also welded to the rear of the the metal tube 11 adjacent the base of the U-shape thereof. Thus each limb of the tube 11, the plate 12 attached thereto and the respective support member 1 3 comprise a respective side of the back rest frame which in the embodiment shown would be connected to a seat base frame (not shown) for pivotable movement relative thereto by means of a back rest recline mechanism (not shown) of a known kind.

Support for a back rest cushion (not shown) is provided by webbing, in this embodiment in the form of a number of straps 1 4 of resilient material, i.e. flexible and stretchable material, e.g. rubber, which extend transversely between the limbs of the metal tube 11. The ends of the straps 1 4 are formed into closed loops 1 5 of folded flexible material, the ends of which are bonded into the resilient portion of the straps 1 4 for a short distance thereof. The straps 14 are retained in position by wire end pieces or connectors 1 6 which each have an open loop portion engaging through the looped end of a respective strap 14 and an open hook portion which engages into a respective hole in the respective limb of the metal tube 11. The free length of the straps 14 will determine the tension therein when fitted to the limbs of the tube 11.

In the lumbar support region of the back rest the webbing comprises another transversely extending strap 1 7 of identical construction and material as straps 14. Strap 1 7 however is wider than strap 14 and, depending on the predetermined characteristics required, the resilient portion may be thicker than straps 14 and/or compounded in a different manner to provide more or less resilience. One end (which is not shown in Fig. 1) of strap 1 7 may be secured to a limb of the metal tube 11 in a similar manner to straps 14 whilst the flexible loop 15a on the other end is engaged by a wire end piece or connector 1 8 comprising a rectangular closed loop, the ends of the wire either overlapping or abutting within the flexible loop to form one side of the rectangle. The opposite side of the rectangular end piece 1 8 is located over a side of a mounting bracket 1 9 of a tension adjusting device in a manner and for a purpose to be described later.

As shown in Figs. 2 and 3, the mounting bracket 1 9 is formed substantially as a hollow rectangle having sides 20, 21, 22 and 23 with an open portion between sides 20 and 23. A hole in side 23 receives a headed cylindrical bush 24 having a screw-threaded through-bore 24a formed therein, such that the underside of the head 24b of the bush 24 abuts the inner surface of side 23 and is welded thereto and the shank of the bush extends outwardly of the outer surface of side 23 with its axis normal to the plane thereof.

The end of side 20 is welded to one limb of tube 11 with the upper edge of side 20 substantially in line with the upper edge of plate 1 2 and the shank of bush 24 engages through a hole in plate 1 2 such that the outer face of side 23 of bracket 1 9 abuts the inner face of plate 1 2. The shank of the bush 24 and the plate 1 2 may then be secured together by suitable welding.

Side 21 of bracket 19 is formed with two horizontal inwardly extending spaced-apart ears 25 between which is pivotably mounted a doubly-armed lever 26 for rotation about a hollow tubular rivet 27 engaging into holes 28 in the ears 25 and secured thereto.

One arm of the lever 26 terminates in a hook 29 which engages around the side of the wire end piece 1 8 within bracket 1 9 as shown. The hook 29 of lever 26 is in registration with a slot 30 in bracket 1 9 which extends along both the adjacent sides 20 and 21 of the bracket 19 in a direction parallel to the plane of rotation of the lever 26 to provide clearance for freedom of movement of the lever 26. Projecting portions 31 on the upper and lower edges of side 21 adjacent the corner formed between sides 20 and 21 provide shoulders to restrict movement of the wire end piece 18 along side 21 towards the centre thereof.

The end of the other arm of lever 26 is formed with an arcuate surface 32 which registers with the screw-threaded bore of bush 24 adjacent the head 24b of the bush 24.

The surface 32 is in contact with the partspherical end 33 of a screw-threaded rod 34 which is threadedly engaged within the bore 24a of the bush 24. The opposite end of the rod 34 is provided with a control handwheel 35 so that the rod can be rotated.

Rotation of the handwheel 35 in a clockwise direction (as viewed in Fig. 2) rotates the rod 34 so that it moves further into the bush 24 whereupon the part-spherical ehd 33 of the rod 34 causes the lever 26 to pivot anticlockwise (as viewed in Fig. 3). This in turn causes the hook 29 on the lever 26 and the wire end piece 1 8 engaged thereby to move towards the tube 11 and thus increase the tension in strap 1 7 to provide a firmer lumbar support condition. Conversely, anticlockwise rotation of the handwheel 35 will reduce tension in the strap 1 7 to a minimum value occurring when the side of the wire end piece 1 8 engaged by the hook 29 contacts the inner surface of side 21 of the bracket 19.

With the exception of the control handwheel 35, the back rest frame and the tension adjusting device for strap 1 7 mounted thereon will of course be normally covered by upholstery.

It will be appreciated that whilst the particular embodiment described hereinbefore relates to a particular kind of back rest frame construction incorporating means for adjusting the back rest angle relative to the seat frame, the invention can also be applied to other forms of back rest constructions which may or may not incorporate means for tilting the back rest relative to the seat.

It will also be appreciated that a second tension adjusting device similar in construction to that described above may be provided at the other end (not shown) of strap 1 7 so that the tension of strap 1 7 can be adjusted from either or both sides of the back rest.

In the embodiment described above, the plane of rotation of the lever 26 is orientated perpendicular to the longitudinal direction of the limb of the metal tube 11 on which the bracket 19 is mounted. It should be noted that the tension adjusting mechanism for strap 1 7 may be suitably modified such that the lever 26 pivots in a plane which may be at any other angle to the longitudinal direction of that limb of the metal tube 11 so that the handwheel 35 is higher or lower and nearer to the tube 11 than is illustrated in the drawings. This facilitates the location of the handwheel 35 at a convenient i.e. accessible position for manual operation by an occupant of the seat without affecting the efficiency of the tensioning device.

Claims

1. A seat back rest comprising a frame; resilient webbing connected to and extending across the frame; and a tension adjusting device carried by one side member of the frame for adjusting the tension of at least the lumbar support region of the webbing by the application thereto of a force of which the line of action is orientated substantially in the plane of the webbing adjacent the frame side member and substantially perpendicular to the longitudinal direction of the frame side member, said device comprising a mounting element which is secured to the frame side member and which has formed therein a threaded bore of which the axis is substantially parallel to and spaced from the line of action of said applied force, a threaded rod which is threadably engaged within the bore, a lever which is pivotally mounted on the mounting element with one arm of the lever operatively engaged by one end of the threaded rod, the other arm of the lever being connected to the webbing adjacent said frame side member whereby movement of the threaded rod along the axis of said bore inwardly or outwardly of the frame due to rotation of the rod causes the lever to pivot and thereby to apply said force to said webbing respectively to increase or decrease the tension thereof.

2. A seat back rest according to claim 1, in which the mounting element is hollow, has a rectangular cross section and extends rearwardly of the frame side member and the webbing, the lever is pivotally mounted inside the mounting element, and the threaded rod extends through said bore so that said one end of the rod is located in the interior of the mounting element in operative engagement with said other arm of the lever and the other end of the rod projects laterally outwardly of the back rest, and in which there is provided a connector which is secured to the webbing adjacent said frame side member and which is connected to the said one arm of the lever inside the mounting element.

3. A seat back rest according to claim 2, in which the mounting element comprises a plate which is secured to and extends rearwardly of the outer side surface of said frame side member, and an open-ended bracket having a substantially rectangular cross section with one side thereof partially open, the bracket being secured to the frame side member with the partially open side disposed alongside the inward facing surface of said plate, the threaded bore extending through both the plate and the part of the bracket side wall adjacent thereto.

4. A seat back rest according to claim 3, in which the bore is formed in a headed bush which is secured within aligned holes in the plate and the bracket.

5. A seat back rest according to claim 3 or claim 4, in which the plate is also secured to a support strut which is attached to the frame and which is disposed rearwardly of said frame side member.

6. A seat back rest according to any of claims 3 to 5, in which the connector comprises a rectangular wire end piece to which the webbing is secured and through which extends the side wall of the bracket opposite said partially incomplete side thereof.

7. A seat back rest according to claim 6, in which the said one end of the lever is formed with a hook which engages a portion of the wire end piece located within the bracket.

8. A seat back rest according to any of claims 2 to 7, in which the said other end of the lever has an arcuate surface which, in use, is maintained in abutting engagement with the said one end of the rod by the tension of the webbing.

9. A seat back rest according to claim 8, in which said one end of the rod is rounded.

10. A seat back rest according to any of claims 2 to 9, in which a handwheel is provided on the said other end of the rod.

11. A seat back rest according to any of claims 1 to 10, in which the plane of rotation of the lever is perpendicular to the longitudinal direction of the frame side member.

1 2. A seat back rest according to any of claims 1 to 10, in which the plane of rotation of the lever is orientated at an angle to the longitudinal direction of the frame side member.

1

3. A seat back rest according to any of claims 1 to 12, in which the webbing is fixedly connected to a side member of the frame which is opposite said one frame side member which carries the tension adjusting device.

14. A seat back rest according to any of claims 1 to 12, in which at least the lumbar support region of the webbing is connected to a frame side member which is opposite said one frame side member by a second tension adjusting device carried by said opposite frame side member and similar in construction to said first mentioned tension adjusting device.

1 5. A seat back rest according to any of claims 1 to 14, further including upholstery located in front of and supported by said webbing.

1 6. A seat back rest substantially as herein before described with reference to and as illustrated in the accompanying drawings.

1 7. A seat incorporating a seat base frame and a seat back rest according to any of claims 1 to 16 mounted thereon.

18. A seat according to claim 17, in which the seat back rest is pivotally mounted on the seat base frame, means being provided by adjusting the degree of tilting of the seat rest with respect to the seat base frame.

19. A seat incorporating a seat base frame and a seat back rest according to any of claims 1 to 1 5 rigidly secured thereto.

CLAIMS 23 Nov 1979

1. A seat back rest comprising a frame; resilient webbing connected to and extending across and supported by the frame; and a tension adjusting device carried by one side member of the frame for adjusting the tension of at least the lumbar support region of the webbing comprising a mounting on said one side member of the frame, a lever pivotally supported on the mounting to turn about an axis extending parallel to the plane in which the webbing generally lies, one end of the lever lying adjacent and being attached to a side edge of the webbing at least in the lumbar support region thereof so that the edge of the webbing moves with the lever as the lever is turned to vary the tension in the lumbar support region of the webbing and a threaded rod screwed into a threaded bore in the mounting and bearing on the lever at a location spaced from the pivot of the lever to turn the lever and thereby adjust the tension in the lumbar support region of the webbing.