Patent GB-1039131-A (GB)
Title: Improvements in and relating to adjustable length seat-back stays
Inventor: BRADBURY FREDERICK JAMES
IPC: B60N2/02
Filed: 1961-08-14
Abstract: 1039131 Seat adjustments AUTOMOTIVE PRODUCTS CO Ltd 14 Aug 1962 [14 Aug 1961] 29272/61 Index F2S 31 [Also in Divisions E2 and F2] In an hydraulically locked telescopic seat stay for locking an aircraft or road vehicle seatback in any adjustable position, a piston slidable in an hydraulic cylinder comprises a manually and remotely operated valve which when closed produces the hydraulic lock holding the cylinder and piston against relative axial movement, and when open permits liquid flow through the piston in one direction upon application of an external load causing stay contraction (extension) or in the opposite direction when said external load is released for permitting stay extension (contraction). In Fig.1, a cylinder 1 is pivoted at 11 to an aircraft seat-back at a position below the seatback pivot and a piston 4 is pivoted at 10 to the seat mounting. A spring 6 extends the piston into engagement with a limit stop 9. A conical valve member 16 operated by a tappet 17 in a hollow piston rod 5 controls an axial piston port 12 communicating with a cylinder space 14 and, through a radial port or ports 13, an annular cylinder space 15 in which is slidable a supplementary annular piston 21 loaded by a spring 22 against the stop 9. The valve 16 is operated, against a spring 20, by a cam lever 18 which acts on the tappet 17 and is rotated through suitable linkage by the seat occupant through a press button on the seat arm rest. In operation, by pressing the button to open the valve and pushing the seat-back rearwardly, liquid flows from the space 14 into the annular space 15 resulting in the displacement of the supplementary piston 21 and loading of the spring 22. On release of the button the valve closes and the stay and seat back are locked in their adjusted position. If the valve is again opened and the pressure is removed from the seat-back, the stay extends to a further position lockable by valve-reclosure, liquid returns from the annular space 15 to the space 14, and the supplementary piston is returned by the spring 22. In Figs. 4-6 (not shown) in which the stay is normally in the contracted position and is extendable against spring-loading, the cylinder is pivoted to the seat-back at a position above the  seat-back pivot. The valve comprises a spring- loaded ball in the piston and the supplementary piston loads its spring on return contraction. In Fig. 7 (not shown) a stay primarily intended for the seats of road vehicles also permits a seat occupant wearing seat-back-attached safety harness to lean forward without operating the piston valve and pivot the seat-back from its adjusted position, to which it is returned without re-adjustment, and, during crash conditions, provides shock absorption and, during recoil, support for the occupants. A cylinder 56 and piston 64 are pivoted to the seat-back and mounting in a similar manner to that in the embodiment of Fig. 1 A ball valve 73 operated by a cam-actuated tappet 81 controls and axial piston port 72 communicating with a cylinder space 78 and, through a radial port or ports 80, an annular cylinder space 79. The cylinder 56 slides within a casing 60 loaded towards the cylinder by a spring 68. An annular closure plug 58 of the cylinder comprises a passage 85 communicating with the space 79 and a chamber 86 within the casing 60. A ball valve 87 normally opened against a stop 90 by a spring 89 controls the passage 85. In operation, by opening the valve 73 and pushing the seat-back rearwardly, liquid flows from space 78 into the space 79, the excess liquid, due to the difference in areas on the opposite sides of the piston 64, flows through the open valve 87 into the chamber and the spring 68 is compressed. To reduce the incline, the valve is again opened and the spring 68 extends the stay. If the occupant is wearing safety harness and leans forward from a reclining position, the piston transfers liquid from the space 79 to the chamber 86 through the open passage 85 and, since the valve 73 remains closed, the liquid in the space 78 cavitates. On returning to the reclining position the piston comes to rest on reaching the previously adjusted position. In the event of a crash, the seat occupant and seatback tend to move forward rapidly generating high pressure in the space 79 to close the valve 87 and unseat the valve 73 to allow a controlled rate of flow from the space 79 to the space 78 for slow, shock-absorbing stay extension. Due to the harness and seat-back resilience, immediately after impact the recoil throws the occupant and seat-back rearwardly, whereupon pressure generated in the space 78 closes the valve 73 to hydraulically lock the seat-back in position and support the occupant.