EP0026668A2

EP0026668A2 - Seat backrest having an adjustable lumbar support

Info

Publication number: EP0026668A2
Application number: EP80303435A
Authority: EP
Inventors: Otto Harold Arndt; William Leonard Wilton; Leslie Albert Gregory
Original assignee: UOP LLC
Current assignee: Honeywell UOP LLC
Priority date: 1979-09-28
Filing date: 1980-09-29
Publication date: 1981-04-08
Also published as: EP0026668A3

Abstract

A seat backrest having a contourable upholstered portion (not shown) supported by a rigid frame portion (116) includes means to produce a desired supporting contour in the lumbar region of the seat occupant. The contour-producing means includes a lumbar pad (122), a pair of link members (124) connecting the lumbar pad to the frame, and a double threaded shaft means (126) operable via a knob (128) by a seated occupant from the side of the backrest for moving and holding the link members in an infinite number of fixed positions forward of the frame. A second knob (130) allows the occupant to adjust the rake of the pad (122).

Description

Background of the invention

The present invention relates to a vehicle seat and particularly to a seat backrest of the type which includes an internal structure for selectively adjusting the seat cushion contour to provide varying degrees of lumbar support to a seated occupant.
The desirability for providing support for the lumbar region of the back of a seat occupant has long been recognized and various U.S. patents, including 3,807,794; 3,890,000; 3,948,558; 3,973,797; 4,155,592; 4,156,544 and 4,162,807 disclose structures for permitting a fore and aft adjustment of an internal lumbar pad within a back cushion. U.S. Patent 4,184,522 discloses both fore and aft and vertical adjustment of a lumbar support. However, the adjustment is very limited and there are only two vertical positions and three fore and aft positions possible.

Summary

The present invention seeks to provide a lumbar support for a seat back which is steplessly adjustable, is simple to operate by a seated occupant, which provides positive positioning of the lumbar support, which is capable of resisting large forces which might be exerted into the seat back and which has a very substantial range of movement while requiring very little or no additional space for installation as compared to a standard cushion. The invention also provides a lumbar support which progressively increases the amount of positive support afforded by the seat cushion as the lumbar support portion is extended forwardly.

Disclosure of the Invention

According to the present invention there is provided a seat backrest having a rigid back portion and a resilient upholstered seatback cushion member attached to said back portion, a generally horizontal lumbar pad located between said back portion and said cushion, said pad being resilient- _ly biased toward said rigid back portion by said resilient cushion and being mounted to be moved away from the back portion to adjust the degree of lumbar support provided to an occupant in the seat, and which is characterised in that said pad is pivotally mounted to the outer end of a pair of divergent horizontally spaced link members; each of said spaced link members being supported at its inner end for pivotal movement about a pair of vertically spaced trunnions located on each of a pair of threaded adjusting nuts; an adjusting screw having a left-handed thread portion in engagement with one of said adjusting nuts and a right-handed thread portion in engagement with the other of said adjusting nuts; spaced bearing means for rotationally mounting said adjusting screw relative to said back portion; means on said screw for limiting axial motion of said screw relative to said bearing means; and a control means on said screw for rotating said screw to cause said adjusting nuts to move toward or away from each other to cause_said link members to move, respectively, toward a retracted position or toward an extended position.
Desirably, the position of maximum lumbar support can be adjusted vertically by pivoting the link members and lumbar pad by means of a pin which is engaged with an angled slot in a sliding plate. The lumbar pad and support arms.can be tilted slightly up or down to cause the point of maximum lumbar support to be lower or higher, respectively, than when the support arms are not tilted. This tilting movement can be provided by mounting an elongate bracket for rotational movement about the threaded shaft and providing it with a pair of longitudinal slots which engage pins extending radially from the pivot axes of the adjusting nuts. A pin projecting from the elongate bracket can then engage an angled slot in a sliding plate carried by the seat back frame. When the sliding plate is moved axially of the threaded shaft (e.g. by means of a manually-operated actuating knob), the pin on the elongate bracket is forced to move slightly forwardly or rearwardly due to its being in contact with the sides of the angled slot. The movement of the pin causes the elongate bracket to move and the elongate bracket causes the adjusting nuts, the support arms and the lumbar pad carried by them to move also.

Brief Description of the Drawings

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

Figure 1 is a fragmentary perspective view of a seat back frame member incorporating a fore and aft lumbar assembly in an intermediate adjustment position with the seat back cushion removed for clarity;
Figure 2 is a partially broken away, partially sectioned, side view of a seat back with the fore and aft lumbar support structure in its full forward, operative configuration;
Figure 3 is a partially broken away, partially sectioned, side view of a seat back with the fore and aft lumbar support structure in its fully recessed, inoperative position;
Figure 4 is a partially broken away, partially sectioned, top view of a seat back with the fore and aft lumbar support structure in its full forward, operative configuration;
Figure 5 is a front view of the seat back with the cushion removed for clarity and a portion of the lumbar pad broken away;
Figure 6 is an isometric view of the link member shown on the left side of Figure 1;
Figure 7 is a fragmentary, partially broken away perspective view of a seat back frame member incorporating both a fore and aft and a vertical lumbar assembly in an intermediate adjustment position with the seat back cushion removed for clarity;
Figure 8 is a side sectional view of the fore, aft and vertical assembly taken on line VIII-VIII of Figure 12 and illustrating the relationship of the lumbar pad to the back cushion in both the retracted and extended positions of the pad;
Figure 9 is a side view of the fore, aft and vertical assembly illustrating the lumbar pad in its uppermost adjustment position wherein it provides the lowest position of maximum lumbar support;
Figure 10 is a side view similar to Figure 9 but illustrating the lumbar pad in its lowest position wherein it provides the highest position of maximum lumbar support;
Figure 11 is a view similar to Figure 10 but illustrating the addition of low friction materials to the foam pad and lumbar pad to facilitate sliding;
Figure 12 is a front view of the fore, aft and vertical lumbar assembly with the lumbar pad omitted for clarity; and
Figure 13 is a partially broken away top section view of the fore, aft and vertical assembly taken on line XIII-XIII of Figure 12, but with the lumbar pad added to show its retracted position in solid lines and its extended position in dotted lines.

Description of the Preferred Embodiment

Referring to Figure_'1, a formed metal seat back frame 10 can be seen as having a recessed pocket portion 12 defined by side portions 14 and a back portion 16. A pivot shaft 18 is indicated as passing behind the seat back frame 10 and may be used to pivotally mount the seat back by means of mounting angles (not shown) to brackets 20 formed on the seat base (not shown). A lumbar pad member 24 is preferably formed of metal and has a pair of struck out or welded on hinge portions 26 which each include a bent over tab portion 26'. Each tab portion 26' passes respectively through an aperture 30' and a notch 30" (see Figure 6) formed in one end of a different one of two metal link members 30 and are bent over, as best seen in Figure 4, to pivotally attach the two link members 30 to the pad member 24. The link members 30 are mounted at their other ends to integral pins or trunnions 32', 32" on adjusting nuts 32 which are internally threaded to mate with right-hand and left-hand threaded portions 36', 36" on a shaft 36. The links 30 are each of channel shape to permit them to overlie the shaft 36 as shown in Figure 3 when the lumbar pad is fully retracted. The shaft 36 is mounted in struck out bearing portions 38' which are formed in a metal channel member 38 which is fastened, such as by welding, to the back portion 16. In addition to providing a bearing mounting for the lumbar pad actuating shaft 36, the channel 38 stiffens the back frame 10 and spreads the loading applied by an occupant to the lumbar pad 24 across the back frame. The spaced flange surfaces 38" and the web surface 38"' cooperate with the generally rectangular adjusting nuts 32 to prevent the nuts from rotating as the threaded shaft 36 is turned. Thus, manual rotation of a shaft knob 40 in a clockwise direction will move the nuts 32 in an axial direction away from each other to bring the support pad 24 to the fully operative position shown in Figures 2 and 4. Conversely, movement of the knob 40 in a counterclockwise direction will cause the nuts 32 to approach each other and draw the support pad 24 toward its fully retracted position shown in Figure 3. To control the amount of travel of the nuts 32 and to eliminate jamming of the nuts in their extreme positions, a tubular stop member 42 may be placed over one threaded portion 36" of the shaft as shown in Figure 4 to limit outward movement while a stop tab portion 43 may be formed out of the channel 38 to limit inward movement. Only one end stop 42 is shown since, obviously, contact with one nut will prevent further rotation of the shaft 36. Movement of the shaft 36 relative to the bearing portions 38' is prevented by resilient retaining washers 44. Although the flange and web surfaces 38" and 38"' can guide rectangular nuts 32 and prevent their rotation as explained hereinabove, their main function is to lend strength to the assembly since rotation of the nuts 32 is also prevented by the fact that their integral upper and lower pin or trunnion portions 32', 32" engage an aperture 45 and a slot 46, respectively, in the respective link member 30 while the other ends of the link members 30 are restrained against vertical movement by virtue of being attached to the lumbar pad member 24 which is mounted in a pocket 50 formed in the back surface of a foam cushion 52. The provision of a slot 46 rather than an aperture at the bottom of each link member 30, facilitates the assembly of the respective link member to the nut 32 and is as satisfactory as an aperture, since the weight of the lumbar pad assembly at the outer end of the link member will ensure that it is the recessed end portion of the slot 46 which is always loaded.
The lumbar pad member 24 is shown as being slightly curved and somewhat loosely mounted to the link members 30.. The curved shape increases its strength, reduces its loading on the foam cushion 52 along its longitudinal edges and permits a small degree of pivotal movement to take place to better conform to the loading applied by a seat occupant and thus increase comfort. To provide rapid adjustment, the threaded portions 36', 36" are preferably provided with Acme double lead threads.
Referring to Figure 7, an improved fore, aft and vertical lumbar adjustment assembly is indicated generally at 110 as being disposed in a recessed portion 112 of a seat back frame 114 having a back panel portion 116 and side panel portions 118. The generally horizontal, elongate lumbar pad member 122 has a convex forward surface and is adapted to be moved by the adjustment assembly in both in and out directions and also in slightly tilting directions. The lumbar pad member 122 is pivotally mounted at the outer end of pivot links 124. The pivot links 124 are mounted at their inner ends for movement relative to a threaded shaft 126 which is journalled for rotation in the recessed portion 112 between the side panel portions 118. The shaft 126 has right-and left-hand threaded portions 126', 126" which permit the inner ends of the links 124 to be moved axially of the shaft 126 and either toward or away from each other depending upon the direction of rotation of a manually operated fore and aft adjustment handle 128 which is mounted on the shaft 126. Tilting movement of the lumbar pad member 122 is provided by rotating a second handle 130. The pad member 122 is pivotally attached to the links 124 by any suitable means such as the pair of brackets 134 which are shown as separate elements but which could also be struck out of the material of the pad member 122. The inner ends of the links 124 are apertured so that they will cooperate with upper and lower trunnion pins 136, 138 which project from adjusting nut members 140, 140'. The upper trunnion pins 136 are engaged by elongate, axially extending, upper trunnion engaging slots 144 formed in a bracket member 146. The bracket member 146 is generally of a shallow U-shape and is mounted for a limited degree of rotation about the shaft 126 by means of apertured end bracket portions 146' which pivot about the shaft 126. The amount of rotary movement of the bracket member 146 which is possible, is controlled by a pin 148 which is integrally affixed to the top of the bracket member 146. The pin 148 engages the sides of an elongate angled slot 150 positioned in the surface of a sliding plate member 152. The sliding plate member 152 has relieved end portions 152' and 152". It also has an adjustment nut 154 integrally attached thereto which is adapted to be engaged by a threaded adjustment screw 156 which is affixed to the second handle 130. A pair of end bracket members 158 affixed to the side panel portions 118 have slots which cooperate with the relieved end portions 152', 152" to permit the plate 152 to move only in the axial direction of the adjustment screw 156. Since the bracket member 146 and the pin 148 thereon are restrained against axial movement but are free to pivot about the shaft 126, it will be readily appreciated that axial movement of the sliding plate 152 will cause the angled slot 150 to move relative to the pin 148 and force the pin 148 and the bracket member 146 which supports it to pivot slightly about the shaft 126 in either a forward or rearward direction depending upon the direction of rotation of the second handle 130. This forward or rearward movement of the bracket member 146 will, of course, cause the elongate slots 144 in said bracket member 146 to move forwardly or rearwardly. As the slots 144 are displaced they will carry the trunnion pins 136 with them and thus cause the adjusting nut members 140, l4θ' and the links 124 and the lumbar pad member 122 carried by them to tilt either upwardly or downwardly. A plurality of shaft support brackets 160, 162, 164 and 166 are preferably affixed to an angular support member 168 which is in turn affixed to the back panel portion 116 and have bearing surfaces which engage and support the threaded shaft 126. The intermediate support brackets 162, 164 serve principally to transfer large loads applied by a seat occupant to the lumbar pad member 122 to the back frame 114 while the brackets 160 and 166 serve principally to support the shaft 126 in the region of the end bracket portions 146' and to limit axial movement of the bracket member 146.
In Figure 8 the lumbar pad member 122 is shown in a substantially retracted position while in Figures 9 and 10 it is shown in its fully extended position. In these Figures, a portion of a foam cushion 170 which would be engaged by the lumbar pad member 122 in an actual seat is shown. In Figure 8, the cushion 170 is also shown in dotted lines at 170' in the position it would assume when the lumbar pad member 122 is fully extended in a forward direction and without any tilting of the links 124. In this extended, dotted line, position one can see that the forwardmost point of maximum lumbar support of the cushion is denoted as M. Two other locations, H and L are also denoted. These latter points H and L correspond to the forwardmost upper and lower positions of maximum lumbar support of the cushion when the links 124 are pivoted downwardly as shown in Figure 10 or pivoted upwardly as shown in Figure 9. The distance between H and L represents the total degree of vertical movement of the point of maximum lumbar support provided by the adjustment assembly 110. Since the front face of the lumbar pad member 122 is of a convex shape, one can readily see that the low adjustment point L will be achieved when the pad is moved upwardly as shown in Figure 9 and that the highest adjustment point H will be achieved when the pad is tilted downwardly as shown in Figure 10.
Although friction between the pad member 122 and the cushion 170 would make tilting movement of the pad member 122 much easier when the links 124 are retracted as shown in Figure 8, it is actually possible to actuate the vertical tilting mechanism by rotating the second handle 130 when the links 124 are in their extended position. However, tilting adjustment in the forward extended position is greatly facilitated by reducing the friction between the cushion 170 and the pad member 122 as shown in Figure 11 wherein a thin, somewhat rigid plastics sheet 172 of polyethylene or other low friction material is mounted inside the cushion 170 while a low friction material such as a layer of nylon cloth 174 is affixed to the front surface of the pad member 122.
Figures 12 and 13 illustrate the adjustment assembly 110 of Figure 7 as it appears from the front and top respectively. Although the structure has been previously described, one can see a pair of resilient retaining washers 178 have been illustrated in Figure 11 for the purpose of retaining the shaft 126 against axial movement relative to the brackets 160, 166.

Claims

1. A seat backrest having a rigid back portion (10,114) and a resilient upholstered seatback cushion member (52,170) attached to said back portion, a generally horizontal lumbar pad (24,122) located between said back portion (10,114) and said cushion (52,170), said pad (24,122) being resiliently biased toward said rigid back portion (10,114) by said resilient cushion (52,170) and being mounted to be moved away from the back portion (10.114) to adjust the degree of lumbar support provided to an occupant in the seat, characterised in that said pad (24,122) is pivotally mounted to the outer end of a pair of divergent horizontally spaced link members (30,124); each of said spaced link members (30,124) being supported at its inner end for pivotal movement about a pair of vertically spaced trunnions (32',32", 136) located on each of a pair of threaded adjusting nuts (32,140); an adjusting screw (36,126) having a left-handed thread portion in engagement with one of said adjusting nuts and a right-handed thread portion in engagement with the other of said adjusting nuts; spaced bearing means (38' 160, 166) for rotationally mounting said adjusting screw (36,126) relative to said back portion (10,114); means on said screw (44,178) for limiting axial motion of said screw (36,126) relative to said bearing means (38', 160, 166); and a control means (40,128) on said screw (36,126) for rotating said screw to cause said adjusting nuts (32,140) to move toward or away from each other to cause said link members (30,124) to move, respectively, toward a retracted position or toward an extended position.

2. A seat backrest according to claim 1, characterised in that a second control means (130,148,150, 156,154,152) is mounted on said rigid back portion (114) for producing a limited degree of rotation of said adjusting nuts (140, 1401) about said adjusting shaft (126) and causing a corresponding pivotal movement of said link members (124) of said lumbar pad (122) so as to tilt said lumbar pad (122) and vary the vertical position of the forward-most portion (L,H,M) of its convex- shaped forward surface relative to the back portion (114).

3. A seat backrest according to claim 2, characterised in that, said second control means (130,152) includes a first member (146) which is fixed against axial movement but can rotate slightly about said adjusting shaft (126) and has slot portions (144) which engage one of the trunnions (136) on each adjusting nut (140,140'), said second control means further including a second member (152) which can move in a path parallel to the axis of said adjusting shaft (126), and cooperating means (148,150) on said first and second members for causing said first member (146) to rotate when said second member (152) is moved longitudinally.

4. A seat backrest according to claim 2 or claim 3, characterised in that said cooperating means includes a pin (148) fixed to one of said first and second members and an angled slot (150) in the other of said first and second members.

5. A seat backrest according to any preceding claim, characterised in that at least one layer of low friction material (172,174) is positioned between the forward surface of said lumbar pad (122) and the portion of said cushion member (170) which is adapted to be engaged by said pad.

6. A seat backrest according to claim 5, characterised in that a layer of thin but relatively rigid low friction plastics material (172) is attached to the back surface of said cushion member and a layer of low friction woven material (174) is adhered to the forward surface of said lumbar pad (122).

7. A seat backrest according to any of claims 2 to 6, characterised in that said second member has a threaded nut means (154) thereon which is engaged by a threaded adjustment screw (156) mounted on said back portion, said second member (152) having longitudinally extending end portions (152', 152") which cooperate with apertured brackets (158) affixed to opposite sides of said back portion to permit said second member (152) to move longitudinally while restraining it against rotary movement.

8. A seat backrest according to any preceding claim characterised in that said cushion member (52, 170) includes a recessed area-in its rear surface for receiving said lumbar pad (24, 122).

9. A seat backrest according to claim 1 characterised in that a generally horizontal support member (38) is affixed to said rigid back portion (10), said support member (38) serving to increase the rigidity of the back member and having said spaced bearing means (38') integral therewith.

10. A seat backrest according to claim 9 characterised in that said support member (38) is a metal channel having a vertical rear web portion (38."') attached to said back portion (16) and upper and lower flange portions (38") extending forwardly.

11. A seat backrest according to claim 10 characterised in that said spaced bearing means (38') support said adjusting screw (36) for rotation in the space between said upper and lower flange portions (38"), said adjusting nuts (32) and their trunnion portions (32', 32") having a shape generally complementary to that of said metal channel so as to guide said nuts (32) for axial movement while preventing said adjusting nuts (32) from rotating when said screw (36) is rotated.

12. A seat backrest according to any preceding claim characterised in that said adjusting screw (36, 126) and said adjusting nuts (32, 140, 140') each have double lead threads.

13. A seat backrest according to any of claims 9 to 12, characterised in that movement limitation means (42, 43) are mounted relative to said adjusting screw (36) so as to limit the axial extent of movement of said adjusting nuts (32) in both of their directions of movement.

14. A seat backrest according to any of claims 9 to 13, characterised in that said link members (30) are generally channel shaped and include apertures (45, 46) in each of their flanges at one end which engage said trunnions (32', 32") on said adjusting nuts (32).

15. A seat backrest according to claim 14, characterised in that said link members (30) include apertures at their other end (30', 30") which are complementary to tabs (26') formed on said lumbar pad (24) and engaged therewith sufficiently loosely so as to permit some pivotal movement of said lumbar pad (24) about a horizontal axis in response to pressure applied to said cushion member (52) above or below said horizontal axis by an occupant.

16. A seat backrest according to any of claims 1 or 9 to 15, characterised in that said link members (30) are generally parallel to the screw (36) in the retracted position and generally perpendicular to the screw (36) in the extended position.