GB1032392A - Improvements in engine starting - Google Patents

Abstract

1,032,392. Engine turning gear. BRITISH AIRCRAFT CORPORATION (OPERATING) Ltd. July 27, 1964 [May 15, 1963; Oct. 3, 1963], Nos. 19259/63 and 39079/63. Heading F1K. A mechanism for starting a prime mover and driving a primary power consumer, e.g. an i.c. engine, a gas turbine or the drive of a jet thrust supported vehicle, comprises an hydraulic motor in controlled supply connection with a source of stored hydraulic energy and in driving connection with a high inertia load capable of being coupled with the prime mover by means of a first freewheel, a gear train and a starting clutch, the prime mover being connected through a second freewheel and the gear train to drive the high inertia load on engagement of a synchromesh device. A diagrammatic lay-out of such a mechanism is shown in Fig. 1, an hydraulic starter motor 303 connected with a reservoir 300 being supplied from an hydraulic accumulator 305 and driving a flywheel 302 coupled with the primary power consumer (not shown), also driving through a freewheel 311 a gear train 312. When sufficient speed has been attained by the flywheel 302, a clutch 306 is engaged so that the flywheel 302 turns an engine 301 by means of the freewheel 311 and clutch 306 in order to start the engine. The engine 301 is run up to its idling speed, driving the gear train 312 and an hydraulic pump 304 through a second free wheel 308. The clutch 306 is then disengaged, and the freewheel 311 is overrun by the engine 301. The hydraulic pump 304 then feeds the hydraulic motor 303 through a restrictor valve 314, allowing the motor 303 to turn the flywheel 302 at a lower speed. Where the primary power consumer is the drive of a jet thrust supported vehicle of the type described in Specification 1,032,391 this allows the vehicle to be driven cross-country across rough terrain without damaging the bearings of the flywheel and the ducted fans by "brinalling". In order to engage the flywheel 302 with the engine 301, the restrictor valve 314 is fully opened so as to allow full torque to be applied by the hydraulic motor 303 to the flywheel 302 and thus to accelerate it. The engine 301 then drives the pump 304 so as to maintain maximum output of the hydraulic motor 303. A baulk ring synchromesh device 309 is spring-loaded by means of two levers 310, 316 and a spring 315 in the sense of engagement. Full engagement of the mechanism is prevented by the baulk ring until synchronous speed is attained. On reaching synchronism the mechanism will fully engage, locking the freewheel 311 and allowing the engine 301 to drive the flywheel 302. The flow of hydraulic fluid to the motor 303 may then be restricted by the valve 314 allowing the motor 303 to idle while another freewheel 322 within the motor overruns the motor. The pump 304 may then be utilized as a source of power for the hydraulic drive of a secondary power consumer, for example the power controls of the vehicle, and an auxiliary pump preferably also geared to the gear train 312 is then available as a source of power for the hydraulic drive of another secondary power consumer, for example the wheels of the vehicle. A detailed description of a mechanism of the above type for the starting and driving of a jet thrust supported vehicle of the type described in Specification 1,032,391 is given.