Patent GB-767586-A (GB)
Title: Improved reciprocatory fluid power motors
IPC: F01B17/00
Filed: 1954-07-16
Abstract: 767,586. Fluid-pressure engines; valve gear; pistons. PAGE, V. J. July 16, 1954, No. 10409/53. Classes 122 (1), 122 (2) and 122 (3). In an engine comprising a piston 106 reciprocated in a chamber 105 by pressure fluid, such as for example compressed air, alternately supplied to and exhausted from opposite ends of the piston chamber by a ported piston valve 127 reciprocated in a valve chamber 126 solely by fluid controlled by the piston 106, fluid is supplied to and exhausted from the piston chamber 105 through two pairs of longitudinally spaced main ports 136, 137 and 136A, 137A controlled by the valve 127 and supplied to and exhausted from opposite ends of the valve chamber 126 through two pairs of spaced auxiliary ports 120, 121 and 120A, 121A controlled by the piston. The valve chamber is closed by adjustable end plugs and has a central compressed air inlet 129. The main ports 136, 137 and 136A, 137A each extend from the valve chamber 126 to longitudinal channels 117, 117A respectively formed in the mating face 116 of the cylinder block and communicating through ports 118, 118A with opposite ends of the piston chamber, and the auxiliary ports 120, 121 and 120A, 121A extend from the piston chamber respectively to two further channels 119, 119A also formed in the face 116 and communicating with opposite ends of the piston chamber through ports 140 and 140A. The piston 106 is packed by rings 109 and has grooves 110, 110A adapted to register with valve chamber exhaust ports 111, 111A respectively. The valve has a central groove 128 of such axial length that it is always in communication with the inlet port 129 and connected, by holes 130, 132 and 132A and axial passages 131 in the valve, with grooves 133 and 133A respectively co-operating with ports 136 and 136A and further grooves 134 and 134A respectively cooperating both with ports 137 and 137A and exhaust ports 135 and 135A in the valve block. In the position shown compressed air supplied through port 136, channel 117 and port 118 forces the piston to the right, exhaust from the opposite end occurring through port 118A, channel 117A, port 137A, groove 134A and port 135A. Towards the end of its stroke the piston uncovers port 120 to supply air to the righthand end of the valve 127 and aligns groove 110A with ports 121A and 111A to exhaust the left-hand end of the valve, the latter thereby being moved to its left-hand position to reverse the air connections to the piston chamber and cause the piston to return to its left-hand position where it uncovers port 120A and aligns groove 110 with ports 121 and 111 to cause the valve to return to its original position and the cycle recommences, the piston and valve moving sequentially. Bleed holes 139, 139A of differing diameter and asymmetrically positioned with respect to the axis of the inlet 129 are provided between the ends of the valve chamber and the channels 117, 117A respectively to ensure starting and positive movement of the valve to its limiting positions. The piston speed may be varied by adjustable needle valves 142 (not shown), 142A which constrict the exhaust passages 135, 135A. The piston actuates, through its rod 107, a double-acting pump plunger reciprocable in a bore 151 and comprising split packing rings 163 of nylon clamped between metal plates 162 urged apart by a compression spring 165.