GB1406221A - Power units - Google Patents

Abstract

1406221 Reciprocating pumps; directacting I C engines; hydraulic accumulators W M B FITZGERALD 14 Nov 1972 [18 Nov 1971] 53721/71 Headings F1A, F1B and F1D A power unit, e.g. for supplying hydraulic pressure to vehicle wheel motors, comprises opposed compression-ignition engine pistons 104, Fig.1, abutting respective pump plungers 113 each reciprocable in a chamber 112 having a fixed displacement accumulator piston 123 which absorbs some of the pump discharge during the outward stroke and releases it to effect the return stroke. Movement of accumulator piston 123 is limited by a stop 129 and a sleeve 121 within which a piston 122 is slidable, space 124 containing pressurized gas, e.g. nitrogen, and space 125 containing oil, the quantity of which is adjustable via port 126. Liquid under pressure enters each pump chamber 112 via a chamber 132E, having a gas-loaded diaphragm 132D, and a quick-acting inlet check valve 133, comprising a spring-loaded grid member, Figs. 9 and 10 (not shown), discharge taking place via a similar quick-acting check valve 134 communicating with an outlet chamber having an accumulator with a gas-loaded piston (136), Fig.6 (not shown). During the compression stroke of pistons 104, fuel is injected through nozzle 201 by an injection pump 200 comprising a piston 211, Fig. 18, moved on its discharge stroke by hydraulic pressure supplied beneath the piston by a free piston 263 under the control of a valve 259 actuated by the combustion chamber pressure, the stroke of piston 263, and hence the stroke of pump piston 211, being controlled by a manually and automatically controlled valve 267, connecting piston 263 to an accumulator 268, 272, to control the quantity of fuel injected. Fuel is supplied under pressure to pump chamber 212 via a check valve in inlet 231 and port 214, and is discharged via check valve 204 and nozzle 201, fuel being supplied to fill nozzle 201 before starting. Combustion air enters engine cylinder 101, Fig.1, via check valves 143 and manifold ports 102 from compression chambers 117 behind the pistons 104, air being fed to chambers 117 via check valves 141 either directly, or from a compressor 146 driven by the exhaust gases from exhaust ports 103 when the exhaust pressure rises sufficiently to close valve 160. Pistons 104 are held in their rest positions by hydraulicallyactuated detents 170, and are synchronized by sensing the times when grooves 119 are uncovered by their respective pump plungers 113, and using the pressure signals so produced to adjust the pressures in respective accumulator chambers 125 to adjust the return pressures on the piston assemblies. A spring-loaded, inertia-actuated piston 115 within pump plunger 113 pumps oil through passage 164 to the engine piston rings 166. A control system for starting and stopping the engine is described, including hydraulicallyactuated detents and valves for preventing starting until the correct system pressure is reached, Figs. 27 and 41 (not shown).