Patent GB-1367937-A (GB)
Title: Hydropneumatic spring locking device and an adjustable seat having such a device
IPC: A47C1/024
Filed: 1971-06-28
Abstract: 1367937 Lockable hydropneumatic actuators NISSAN MOTOR CO Ltd and IKEDA BUSSAN CO Ltd 28 June 1971 [24 July 1970 (2) 28 Dec 1970 (2)] 30098/71 Headings F2S [Also in Division E2] A hydropneumatic spring-locking device comprises a cylinder 15 divided into two chambers 27, 28 by a floating piston 29, chamber 28 being filled with a gas under pressure and chamber 27 being filled with a liquid and being divided into two compartments by a piston 18, the two compartments being interconnected by a passage 20 in the piston 18, the passage being closed by a valve member 25 on a piston-rod 21 screwed to the piston such that rotation of the cylinder causes axial movement of the piston relative to the piston-rod to open the passage, the looking device including a spring which biases the cylinder to a passage-closing position and means for restraining the degree of clamping of the valve member against the valve seat when the passage is closed. In the first embodiment shown in Fig. 4 the restraining means includes a pair of spaced limbs 39, 39<SP>1</SP> axially extending from the cylinder and between which a member which is non-rotatable about the axis of the cylinder is interposed to prevent rotation of the cylinder when one of the spaced limbs abuts the member. The member may be a vehicle seat back rest support bracket (12) (Fig. 2, not shown) for pivotally connecting the backrest to a seat rest. A lever 37 for rotating the cylinder is fixed to the cylinder and the spring for biasing the cylinder to a passage closing position is connected at one end to the lever and at other end to the member. In the second embodiment shown in Fig. 5, the restraining means comprises a bifurcated member 40 having spaced limbs 40a, 40b, extending radially of the cylinder and between which an adjustment'lever 41 which is pivotally connected to the member, e.g. the bracket (12), by a stud 36 extends such that movement of the lever about stud 36 causes rotation of the cylinder and rotation of the cylinder is limited by engagement of an upwardly extending portion 41b on the lever with the cylinder. In the third embodiment shown in Fig. 7 the restraining means comprises a valve member 42 of resilient material formed with a hole extending radially of the cylinder and in alignment with a hole in the piston-rod, a cotter 43 being positioned within the aligned holes such that excessive force applied to the valve member by rotation of the cylinder causes deformation of the valve member. In a modification of this embodiment (Fig. 10, not shown) an annular spring washer 46<SP>1</SP> may be mounted on the piston-rod between the valve member and a shoulder on the piston-rod. When the locking device is connected to a vehicle seat the forward end of the piston-rod is connected to the vehicle seat-rest by an eye 34 and the rearward end of the cylinder is connected to the backrest bracket (12) through a connecting rod having an eye 35 pivotally connected to the bracket and a screw threaded portion 32 engaged in a bore 31 provided on the end of the cylinder such that the cylinder can be rotated relative to the bracket to open the passage. Build-up of frictional force between the bore and rod is prevented by the arrangement shown in Fig. 11 in which a ball 47 is positioned in a cup-shaped member 46 mounted on the end wall of the cylinder and is pressed upon a ball seat 48, the ball and ball seat being of rigid, low friction, abrasion-free material.