GB796226A - Internal combustion free-piston engine - Google Patents

Abstract

796,226. Free-piston engines. AMERICAN MACHINE & FOUNDRY CO. April 26, 1955 [July 26, 1954], No. 11980/55. Classes 7(1) and 7(2) An internal - combustion free - piston engine comprises a cylinder, a pair of opposed pistons reciprocably mounted in the cylinder, the pistons including pumping and bounce means, the pumping means being adapted to pump a hydraulic fluid into a first duct and first accumulator means capable of storing hydraulic fluid under pressure, the bounce means being adapted to receive hydraulic fluid under pressure to cause a compression stroke of the pistons, and an automatic control mechanism operated by the hydraulic fluid under pressure, the control mechanism being adapted to cut off the hydraulic fluid to the bounce means when the pressure produced by the pumping means exceeds a predetermined maximum pressure and to open communication for the hydraulic fluid when the pressure is less than a predetermined minimum pressure. In Fig. 1, when the pressure control valve 66 has received the signal-that the accumulator pressure has reached a minimum value and requires recharging from the engine valve 80 is opened and hydraulic fluid flows from the accumulator 50 and forces return pistons 30 inwardly thereby driving pistons 22 through their compression stroke. After ignition hydraulic fluid from pump cylinders 28 is forced into pneumatic accumulator 50 through check valve 60. Hydraulic fluid from the return cylinders is returned to the accumulator 50 through the valve 66. When accumulator 50 reaches full charge the pressure control valve 66 will close and thereby stop the engine. A hydraulic pump motor 44 may be driven by hydraulic fluid from the accumulator 50. When the turbine 42 is in operation pump motor 44 pumps fluid into the accumulator. The hydraulic motor 78 may be of any well-known type, it may be a hydraulic turbine. In a modification Fig. 2, (not shown), there may be a second hydraulic accumulator whose sole purpose is to drive the pistons through the compression stroke. The exhaust turbine 42 may be omitted. In Fig. 3, if the high pressure accumulator 350 is not fully charged the control valve 376 opens at the end of the power stroke of the engine. Fluid from the low pressure accumulator 398 then drives the pistons 322 on the compression portion of the cycle. Scavenging air is supplied by the compressors 347. Fig. 6 shows a modified form of piston which may be used in the arrangement of Figs. 1 and 2. Fluid is forced under high pressure through conduit 458 to the high pressure accumulator. Fluid which drives the pistons on the return stroke is supplied to an annular space 403. In Fig. 8, hydraulic fluid enters through conduit 564 into the cylinder 506 and drives the piston on its compression stroke. Fluid from the sump enters cylinder 505 through conduit 557. On the firing portion of the engine cycle this fluid is forced through the cylinder 507 to a high pressure accumulator.