GB1588711A - Vehicle seats - Google Patents

Description

(54) VEHICLE SEATS (71) We, H. R. TURNER (WIL LENHALL) LIMITED, a British Company of Holly Lane, Great Wyrley, Walsall, West Midlands, England, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following state ment :- This invention relates to vehicle seats of the kind comprising a seat base and a back rest, in which the backrest comprises a main frame bridged by a back-supporting area.

The object of the invention is to provide a vehicle seat of this kind in which the backrest is provided with means for adjusting the profile of part thereof to afford greater comfort for the occupant, especially in the lumbar regions.

According to the invention we provide a vehicle seat of the kind referred to which includes a sub-frame mounted within the confines of the main frame and adjustable forwardly and rearwardly of the seat so as to move said back-supporting area forwardly and rearwardly over a part of the backrest, and means for selectively adjusting the position of said sub-frame, the adjustment mechanism comprising a self-locking pinion device and gear assembly in which the pinion comprises at least two gear-engaging elements and is so arranged that two of said elements can fully mesh with the gear teeth at the same time.

Preferably said part is located at the lower region of the backrest and the sub-frame has its free ends hingedly connected to opposite sides of the main frame so that the sub-frame can swing about a generally horizontal axis when the seat is in the normal position of use, said sub-frame including spaced apart cranked portions which co-operate with said back-supporting area.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a front view of a vehicle seat structure prior to being trimmed.

Figure 2 is a side view; Figures 3 and 4 are enlarged views of the adjustment mechanism of the embodiment of Figures 1 and 2; and Figure 5 is a view of an alternative form of adjustment mechanism to that shown in Figures 2-4.

Referring now to Figures 1 to 4, the seat comprises a backrest frame 110 and seat base frame 112 hinged together at 114. A backsupporting framework 116 is supported within the confines of the frame 110 and comprises a pair of rods 118 each connected to the adjacent limbs of the frame 110 by springs 119 and a series of wires or straps 120 anchored to the rods 118. At their lower ends, the rods 118 are encircled by plastics sleeves 122 and are joined by a crosspiece 123. A sub-frame 124 is provided whose ends 126 are journalled in the sides of the frame 110 and which has cranked portions 128 which bear against the sleeves 122. By rotating the sub-frame in the appropriate sense about its ends 126 the lower part of the framework 116 is displaced forwardly to vary the profile of the backrest in the lumbar regions of the occupant.

Referring particularly to Figures 2 to 4, the adjustment mechanism comprises a toothed disc 130 fast with one end 126 of the subframe, a pinion 132 in mesh with disc 130, a gear 134 fast with the pinion 132 and a drive rotor 136 connected to a handle 138 (see Figure 1) and is mesh with gear 134. The rotor 136 comprises a disc 140, concentric with stub axle 142, and a pair of pins 144 which are located on diametrically opposite sides of the rotor axis. The pins 144 are shaped and dimensioned so as to fit closely into the roots of the intertooth spaces of the gear 134.

The rotor is mounted at one side of the frame 110 for movement radially towards and away from the axis of the pinion 132.

Spring 133 biases the rotor towards the pinion axis. By rotating the rotor 136, the subframe is displaced angularly via the gear 134, pinion 132 and toothed disc 130. During turning of the rotor, it will be noted that the rotor moves radially with respect to axis of the pinion 132. If the rotor is left in a position in which one pin is engaged and the other pin is disengaged, the spring 133 is effective to snap the rotor back into a position in which both pins are fully engaged. When in this position, the rotor acts as a locking device in counteracting any tendency for the subframe to move inadvertantly.

Figure 5 shows a modification of the mechanism shown in Figures 2 to 4, in which the rotor 150 has three pins 150A, B and C distributed uniformly about its axis. In this embodiment, the rotor is free to move in a plane perpendicular to its axis but is constrained by a fixed guide aperture 158 whose periphery is profiled to control movement of the rotor as hereinafter explained. The aperture 158 includes a crest 160 whose apex lies on the line passing through axes of the rotor and the gear 134, a concavity 162A and B on each side of the crest 160, and radiussed cusps 1 64A and B having surfaces 1 66A and B whose curvatures at least approximates to that of the tooth flanks of gear 134.

To illustrate operation of the device, suppose that it is desired to adjust the sub-frame forwardly from the illustrated position (see Figure 2), then it will be necessary to turn the rotor 150 anticlockwise. Initially, rotation of the device about its axis will be translated into a radial shifting movement caused by turning of the rotor about the pin 150B which remains in engagement with the gear 134 whilst the pin 150C moves out of engagement. Surface 166A assists in constraining the rotor to move in this manner. At this stage, no movement of the gear occurs.

Eventually, the pin 150A of the rotor engages with and seats in concavity 1 62B and further rotation of the rotor 150 is translated into a turning movement about the pin 150A with consequent displacement of the pin 150B and rotation of the gear 134. Such movement continues until the pin ISOC engages with, and seats in, the concavity 16A whereupon the rotation of the rotor is translated into turning about the pin 150C with continued turning of the gear by pin 150B and accompanying movement of the pin 150A towards meshing engagement with the gear. As the pin 150A passes cusp 164B, the effective turning point of the pinion becomes pin 150B and as pin 150A enters the aligned intertooth space, the pin 150C moves into registry with the crest 160.The rotor has by then assumed the stable, locking position illustrated in the drawing and for a 120 rotation of the rotor, the gear 134 has been displaced through one tooth pitch.

It will be noted that the curvature of the surfaces 1 66A and B co-operates with the pins to resist unintended turning of the rotor and that the registry between the crest 160 and the adjacent pin provides a fail-safe feature in the event of breakage of the spring loading the pinion radially inwardly. In this event, the pin will engage the crest to overcome the tendency for the rotor to turn due to loading of the sub-frame.

In a modification of the illustrated embodiment, a cam may be associated with the pins and the cam, rather than the pins, may cooperate directly with the profiled aperture, the cam having a suitably shaped profile for this purpose. Direct engagement between the pins and the profiled aperture is not favoured because of the increased wear to which the pins are subject. The advantages of the rotor device shown in Figure 5 compared with that of Figures 2-4 are that the extent of the radial shift or wobble is reduced and the rotational movement per tooth pitch advance is 120O instead of 180 . It will be appreciated that it is within the scope of the invention to use four or more pins or other intertooth-meshing elements with appropriate modification of the profiled guide surfaces.

WHAT WE CLAIM IS: 1. A vehicle seat of the kind referred to which includes a sub-frame mounted within the confines of the main frame and -adjustable forwardly and rearwardly of the seat so as to move said back-supporting area forwardly and rearwardly over a part of the backrest, and means for selectively adjusting the position of said sub-frame, the adjustment mechanism comprising a self-locking pinion device and gear assembly in which the pinion comprises at least two gear-engaging elements and is so arranged that two of said elements can fully mesh with the gear teeth at the same time.

2. A vehicle seat as claimed in Claim 1 in which said pinion device comprises three of said elements spaced about its rotary axis and is movable in two degrees of freedom in a plane perpendicular to its rotary axis, means being provided to constrain the pinion device so that its rotary axis and each said element follow a predetermined closed path in said plane during rotation of the pinion device.

3. A vehicle seat as claimed in Claim 2 in which said constraining means comprises a guide with which the pinion device is cooperable, the guide including means in which said elements can temporarily seat one at a time either directly or via a cam so as to translate rotation of the pinion device about its axis into a turning movement of the pinion device about the seated element which is effective to impart movement of said gear.

4. A vehicle seat as claimed in Claim 1, 2 or 3, in which said part is located at the lower region of the backrest and the sub-frame has its free ends hingedly connected to opposite sides of the main frame so that the sub-frame can swing about a generally horizontal axis when the seat is in the normal position of use, said sub-frame including spaced apart cranked portions which co-operate with said back-supporting area.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. is disengaged, the spring 133 is effective to snap the rotor back into a position in which both pins are fully engaged. When in this position, the rotor acts as a locking device in counteracting any tendency for the subframe to move inadvertantly. Figure 5 shows a modification of the mechanism shown in Figures 2 to 4, in which the rotor 150 has three pins 150A, B and C distributed uniformly about its axis. In this embodiment, the rotor is free to move in a plane perpendicular to its axis but is constrained by a fixed guide aperture 158 whose periphery is profiled to control movement of the rotor as hereinafter explained. The aperture 158 includes a crest 160 whose apex lies on the line passing through axes of the rotor and the gear 134, a concavity 162A and B on each side of the crest 160, and radiussed cusps 1 64A and B having surfaces 1 66A and B whose curvatures at least approximates to that of the tooth flanks of gear 134. To illustrate operation of the device, suppose that it is desired to adjust the sub-frame forwardly from the illustrated position (see Figure 2), then it will be necessary to turn the rotor 150 anticlockwise. Initially, rotation of the device about its axis will be translated into a radial shifting movement caused by turning of the rotor about the pin 150B which remains in engagement with the gear 134 whilst the pin 150C moves out of engagement. Surface 166A assists in constraining the rotor to move in this manner. At this stage, no movement of the gear occurs. Eventually, the pin 150A of the rotor engages with and seats in concavity 1 62B and further rotation of the rotor 150 is translated into a turning movement about the pin 150A with consequent displacement of the pin 150B and rotation of the gear 134. Such movement continues until the pin ISOC engages with, and seats in, the concavity 16A whereupon the rotation of the rotor is translated into turning about the pin 150C with continued turning of the gear by pin 150B and accompanying movement of the pin 150A towards meshing engagement with the gear. As the pin 150A passes cusp 164B, the effective turning point of the pinion becomes pin 150B and as pin 150A enters the aligned intertooth space, the pin 150C moves into registry with the crest 160.The rotor has by then assumed the stable, locking position illustrated in the drawing and for a 120 rotation of the rotor, the gear 134 has been displaced through one tooth pitch. It will be noted that the curvature of the surfaces 1 66A and B co-operates with the pins to resist unintended turning of the rotor and that the registry between the crest 160 and the adjacent pin provides a fail-safe feature in the event of breakage of the spring loading the pinion radially inwardly. In this event, the pin will engage the crest to overcome the tendency for the rotor to turn due to loading of the sub-frame. In a modification of the illustrated embodiment, a cam may be associated with the pins and the cam, rather than the pins, may cooperate directly with the profiled aperture, the cam having a suitably shaped profile for this purpose. Direct engagement between the pins and the profiled aperture is not favoured because of the increased wear to which the pins are subject. The advantages of the rotor device shown in Figure 5 compared with that of Figures 2-4 are that the extent of the radial shift or wobble is reduced and the rotational movement per tooth pitch advance is 120O instead of 180 . It will be appreciated that it is within the scope of the invention to use four or more pins or other intertooth-meshing elements with appropriate modification of the profiled guide surfaces. WHAT WE CLAIM IS:

1. A vehicle seat of the kind referred to which includes a sub-frame mounted within the confines of the main frame and -adjustable forwardly and rearwardly of the seat so as to move said back-supporting area forwardly and rearwardly over a part of the backrest, and means for selectively adjusting the position of said sub-frame, the adjustment mechanism comprising a self-locking pinion device and gear assembly in which the pinion comprises at least two gear-engaging elements and is so arranged that two of said elements can fully mesh with the gear teeth at the same time.

2. A vehicle seat as claimed in Claim 1 in which said pinion device comprises three of said elements spaced about its rotary axis and is movable in two degrees of freedom in a plane perpendicular to its rotary axis, means being provided to constrain the pinion device so that its rotary axis and each said element follow a predetermined closed path in said plane during rotation of the pinion device.

3. A vehicle seat as claimed in Claim 2 in which said constraining means comprises a guide with which the pinion device is cooperable, the guide including means in which said elements can temporarily seat one at a time either directly or via a cam so as to translate rotation of the pinion device about its axis into a turning movement of the pinion device about the seated element which is effective to impart movement of said gear.

4. A vehicle seat as claimed in Claim 1, 2 or 3, in which said part is located at the lower region of the backrest and the sub-frame has its free ends hingedly connected to opposite sides of the main frame so that the sub-frame can swing about a generally horizontal axis when the seat is in the normal position of use, said sub-frame including spaced apart cranked portions which co-operate with said back-supporting area.

5. A vehicle seat substantially as

hereinbefore described with reference to, and as shown in, the accompanying drawings.