Seat with adjustable lumbar support

Abstract: A vehicle seat (10) having a seat base (12) and a seat back (14) including an adjustable lumbar support member (70) is disclosed for enhancing passenger comfort and reducing passenger fatigue during long trips. The seat back (14) includes a pelvic support member (60) and a thoracic support member (74) flexibly interconnected to the lumbar support member (70) such that when the lumbar support member is adjusted, the pelvic and thoracic support members adjust to provide improved support for the back of the passenger.

Description: Field of the invention This invention relates generally to a seat for a motor vehicle according to the preamble claim 1. The invention is more specifically concerned with the provision of an adjustable lumbar support in the seat. Background of the invention Such a seat is known from US-A-4 469 374. Seat designers often incorporate adjustable lumbar support mechanisms in their designs to help reduce fatigue experienced by the occupant of the seat, who may be the driver or a passenger, during extended rides. One such example is disclosed in this document. These systems typically provide a mechanism or inflatable device located in the seat back adjacent to the lumbar region of the occupant's back. This allows the occupant to adjust the extent to which a lumbar support member protrudes from within the seat back. As a seat occupant begins to experience fatigue, adjusting the position of the lumbar support member can reduce fatigue and increase user satisfaction. The comfort of a seat back is related to the manner in which the seat back distributes the occupant's weight. It has been observed by some users that adjusting the lumbar support member outward from the retracted position can drastically alter this pressure distribution and lead to discomfort. This is especially exacerbated by adjustable lumbar mechanisms that only move the lumbar portion of the seat back forward into the occupant's back. In doing so, load is transferred from the pelvic and thoracic regions and directed to the lumbar area of the back. This pressure concentration significantly detracts from the occupant's comfort. Object of the invention The invention seeks to provide a vehicle seat that will allow the occupant to adjust the lumbar support member through a range of positions while still providing support for the pelvic and thoracic regions of the back. Summary of the invention The present invention provides a passenger seat including a seat back having an adjustable lumbar portion which is connected to other seat back support portions to maintain desirable pressure distribution over all of the surfaces throughout the range of lumbar adjustment. This design enhances passenger comfort and reduces fatigue furing extended rides. According to the present invention we provide a seat for a motor vehicle comprising a seat base and a seat back extending from a rearward edge of said seat base, the seat back comprising: a seat back frame, a lumbar support member, and an actuation means for displacing said lumbar support member, characterised by: a pelvic support member disposed adjacent said seat base and pivotably attached to said back frame and flexibly joined to said lumbar support member; a thoracic support member having a first end flexibly attached to said lumbar support member at the opposite end to that attached to said pelvic support member and a second end pivotably attached to said seat back frame; and said actuation means being also capable of displacing said pelvic support member and said thoracic support member from a retracted position to an extended position, the flexible connections between the support members providing a smooth back support surface for all positions of said lumbar support member. Brief description of the drawings The invention will now be described further, by way of example, with reference to the accompanying drawings, in which :- FIG. 1 is a perspective view of a vehicle seat having an adjustable lumbar support, FIG. 2 is a perspective view of a vehicle seat back having an adjustable lumbar support mechanism in an extended position, FIG. 3 is a perspective view of a passenger seat back having an adjustable lumbar support mechanism in a retracted position, FIG. 4 is a perspective view of an alternative embodiment of a vehicle seat back having an adjustable lumbar support mechanism in an extended position, FIG. 5 is an elevational view of a vehicle seat illustrating the support provided when the lumbar support member is in the retracted position. FIG. 6 is an elevational view of a vehicle seat illustrating the support provided when the lumbar support member is in the extended position. Detailed description of the preferred embodiments Referring now to the figures, FIG. 1 illustrates a vehicle seat 10 for a motor vehicle having a seat base 12 and a seat back 14 extending upward from a rearward edge 15 of the seat base 12. The seat 10 may include a head restraint 16 and a reclining mechanism 18 to allow adjustment of the rake of the seat back 14. The seat back 14 supports an occupant's back with a pelvic support portion 20, a lumbar support portion 22, a thoracic support portion 24 and right and left bolsters 26, 28. FIGS. 2 and 3 illustrate the internal mechanisms of the seat back 14 in fully extended and retracted positions, respectively. A generally U-shaped seat back frame 30 includes first ends 32 for attachment to the seat base 12. This attachment may either be fixed or may provide reclining motion of the seat back 14. The seat back frame 30 further includes upwardly extending right and left sides 34, 36 interconnected by a second end 38 of the seat back frame 30. The seat back frame 30 is augmented by a generally U-shaped articulating frame 40 including right and left first ends 42, each having an aperture 44 for receiving a pivot rod 46 therethrough. The articulating frame 40 further includes right and left upstanding portions 48, 50 extending upward beyond the second end 38 of the seat back frame 30 and interconnected by a second lateral end 52 of the articulating frame 40. Pillow block style fasteners 54 pivotably support the articulating frame 40 on the second end 38 of the seat back frame 30. These fasteners 54 may consist of a simple U-bolt fastened to the upstanding portions 48, 50. To provide for smoother operation, a low friction material, such as PTFE, may be disposed between the moving components of the fastener. The second end 52 of the articulating frame 40 includes adjustable fasteners 56 for attachment of the headrest 16. The seat back 14 includes three principle support members for supporting the back of the passenger. A substantially rigid pelvic support member 60 includes a first edge 62 adjacent to the rearward edge 15 of seat base 12. The first edge 62 includes an aperture 64 for rotatably receiving the pivot rod 46 therethrough. In the illustrated embodiment the pelvic support member 60 is substantially planar, however, it is contemplates that the pelvic support member 60 may be contoured to provide a conforming fit to the pelvis of the occupant. A lumbar support member 70 provides support for the lumbar region 22 of the seat back 14. The lumbar support member 70 includes at least one vertically oriented flexible strap 72 extending from the pelvic support member to a first edge 73 of a thoracic support member 74. At least one lumbar slat 76 extends laterally, transversely to the flexible strap, between right and left ends 78, 80. The lumbar slat 76 is sufficiently rigid to resist deformation under the weight of the back of the occupant. In the illustrated embodiment, lumbar slats 76 include right and left wings 82, 84 disposed on right and left ends 78, 80. The flexible straps 72 may be bonded or secured by threaded fasteners to the pelvic support member 60, the lateral slats 76 and the thoracic support member 74. The thoracic support member 74 includes a second end 90 that is pivotably attached to the second lateral portion 52 of the articulating frame 40. The thoracic support member 74 is substantially rigid, and may be shaped to conform to the thorax of the occupant. In the preferred embodiment the thoracic support member 74 also includes a cylindrical portion 92 extending from the second end 90 to rotatably receive a section of the second lateral portion 52 therein. An actuator mechanism 100 disposed adjacent to the lumbar portion 22 of the seat back 14 provides the ability to adjust the position of the lumbar support member 70. In the illustrated embodiment, the actuator mechanism 100 includes a link 102 having right and left link ends 104, 106 pivotably attached to the first ends 32 of the seat back frame 30. The link 102 further includes right and left intermediate portions 108, 110 slidably and pivotably passing through right and left slots 112 located in right and left upstanding portions 48, 50 of the articulating frame 40. A lumbar portion 116 extends between and connects the right and left intermediate portions 108, 110. When actuated, the lumbar portion 116 urges the lumbar support member 70 between retracted and extended positions. The actuator mechanism 100 further includes a handle 120 mounted on the seat frame 30 and rotatably attached to a cam 122. The cam 122 contacts the right intermediate portion 108 of the link 102. An anti-reversing gear 124 and pawl 126 may be provided to lock the cam 122, link 102 and lumbar support member 70 in an adjusted position. Many alternatives to the described actuator mechanism will occur to those skilled in the art. For example, it is contemplated that an inflatable device, commonly used for lumbar actuation, could readily be installed in place of the lumbar portion 116 of the link 102 to provide similar functionality. Similarly, an electric motor could drive the cam 122. Referring now to Fig. 4, where like numerals refer to like parts, an alternative embodiment of the invention is described that does not have an articulating frame. In this embodiment, the pivot rod 46 attaches to the first end 32 of the seat back frame 30, and the cylindrical portion 92 attaches to the second end 38 of the seat back frame 30. As in the previously described embodiment, an inflatable device or an electric motor could be substituted in the actuator mechanism 100. Those skilled in the art will appreciate the components of the seat can be made from a variety of conventional materials. The seat back frame 30 and the articulating frame 40 can be made from materials capable of sustaining compressive and tensile loads. Such materials include, but are not limited to, steel, aluminium, and high strength synthetic polymeric materials such as high strength polycarbonate. Similarly, the pelvic, lumbar slats and thoracic support members may all be stamped from steel, aluminium and other materials. The flexible straps may be constructed from any elastic material having resilient properties. Referring to Figs. 2-3, 5 and 6, operation of the preferred embodiment will now be described. Figs. 3 and 5 illustrate the lumbar support member 70 adjusted to the fully retracted position. In this position, the flexible straps 72 assume a first radius of curvature when viewed from the side. If it is desired to vary the amount of lumbar support, or simply to change the present posture to improve circulation, the occupant rotates handle 120. This causes the cam 122 to rotate against the right intermediate portion 108 of the link 102, urging the lumbar portion 116 against the lumbar support member 70. The flexible straps 72 of the lumbar support member 70 bend between the lumbar slats 76, allowing the lumbar support member 70 to assume various radii of curvature relative to an axis parallel to a longitudinal axis of the lumbar slats 76. The occupant can adjust the lumbar support member 70 to any position between the fully retracted and fully extended positions. Figs. 2 and 6 illustrate the fully extended position where the flexible strap 72 has assumed a second radius of curvature. As the occupant adjusts the lumbar support member 70, the pelvic support member 60 and the thoracic support member 74 simultaneously adjust to provide a smooth, continuous support surface between all three support members in any adjusted position. Additionally, simultaneous adjustment of the right and left bolsters 26, 28 occurs due to right and left wings 82, 84. In the preferred embodiment, locating the second lateral portion 52 of the articulating frame 40 above the attachment point to the second end 38 of the seat back frame 30 permits the occupant shoulder to rotate rearward relative to the pelvis. This significantly improves the comfort of the occupant.

Claims: A seat for a motor vehicle comprising a seat base (12) and a seat back (14) extending from a rearward edge of said seat base (12), the seat back (14) comprising: a seat back frame (30,40), a lumbar support member (70), and an actuation means (100,102) for displacing said lumbar support member (70), characterised by: a pelvic support member (60) disposed adjacent said seat base (12) and pivotably attached to said back frame (30) and flexibly joined to said lumbar support member (70); a thoracic support member (74) having a first end flexibly attached to said lumbar support member (70) at the opposite end to that attached to said pelvic support member (60) and a second end pivotably attached to said seat back frame (30,40); and said actuation means (100,102) being also capable of displacing said pelvic support member (60) and said thoracic support member (74) from a retracted position to an extended position, the flexible connections between the support members (60,70,74) providing a smooth back support surface for all positions of said lumbar support member (70). A seat for a motor vehicle as claimed in claim 1 comprising a seat base (12) and a seat back (14) supported on a seat back frame (30) having a first end (32) attached to said seat base (12) and a second end (38) opposite therefrom; an articulating frame (40) having right and left first ends (42) disposed adjacent to said seat base (12) and upwardly extending right and left portions (48,50) extending beyond said second end (38) of said seat back frame (30) to a second end (52) interconnecting said right and left upstanding portions (48,50). fastening means disposed on said right and left upstanding portions (48,50) of said articulating frame (40), said fastening means being adapted to pivotably support said articulating frame (40) from said second end (38) of said seat back frame (30); and wherein the pelvic support member (60) has a first edge disposed on a pivot rod (46) extending between said right and left second ends (42) of said articulating frame (40); the lumbar support member (70) is attached to said pelvic support member (60) at the end opposite to said pivot rod (46); the thoracic support member (74) is attached to said lumbar support member (70) at an opposite end to that attached to said pelvic support member (60) and has at its ends remote from the lumbar support (70) a cylindrical portion (92) receiving said second end (52) of said articulating frame (40) therethrough; and the actuation means (100) displaces said lumbar support member (70), said pelvic support, member and said thoracic support member from a retracted position to an extended position, thereby providing a smooth back support surface for all positions of said lumbar support member. A seat as claimed in claim 1 or 2, wherein said lumbar support member (70) further comprises: a flexible strip (42) extending from said pelvic support member (60) to said thoracic support member (74); and a lumbar slat (76) transversely disposed on said flexible strip (72) and having right and left ends. A seat as claimed in claim 3, wherein said lumbar slat (76) further comprises a right wing (82) disposed on said right end (78) of said lumbar said and a left wing (84) disposed on said left end (80) of said lumbar slat, said wings being adapted to support right and left lumbar bolsters (26,28). A seat as claimed in either claim 3 or claim 4, wherein said lumbar support member (70) further comprises: a plurality of lumbar slats (76) transversely disposed on said flexible strip (72), each having right and left ends (78,80), said lumbar slats (76) being operative to permit said lumbar support member to flex from a first radius of curcature in said retracted position to a second radius of curvature in said extended position. A seat a claimed in claim 5, wherein each of said lumbar slats (76) further comprise a right wing (82) disposed on said right end (78) of said lumbar slats and a left wing (84) disposed on said left end (80) of said lumbar slats (76), said wings (82,84) being adapted to support right and left lumbar bolsters (26,28). A seat as claimed in any preceding claim, wherein the lumbar support member (70) is more flexilbe than said pelvic support member (60) and said thoracic support member (74). A seat as claimed in any preceding claim, wherein said pelvic support member (60) and said thoracic support member (74) are substantially rigid members. A seat as claimed in any preceding claim, wherein said actuation means (100) comprises: a crank-shaped link (102) having a transverse portion engaged against said lumbar portion disposed adjacent to said lumbar support member and having right and left link ends pivotably disposed in said seat back frame (30,40); and a handle (120) mounted on said seat frame (30) and to a cam (122), said handle (120) being manually operative to rotate said cam (122) against said link (102) to urge said lumbar support member (70) from said retracted position to said extended position. A seat as claimed in claim 9, wherein aid actuation means (100) further comprises an anti-reversing gear ands a pawl to lock siad cam and said lumbar support member (70) in a desired position.

Inventors: BACH DANIEL CORNELIUS, FRUSTI THOMAS MATTHEW, KUKLA ROBERT FLOYD, BACH, DANIEL CORNELIUS, FRUSTI, THOMAS MATTHEW, KUKLA, ROBERT FLOYD
Applicants: FORD FRANCE, FORD MOTOR CO, FORD WERKE AG, FORD FRANCE S. A., FORD MOTOR COMPANY LIMITED, FORD-WERKE AKTIENGESELLSCHAFT
Application year: 1995
Main classification: B60N2
IPC codes: B60N2, A47C7, A61G5