Patent GB-1423862-A (GB)
Title: Recycle engine apparatus
IPC: F02B47/10
Filed: 1973-03-21
Abstract: 1423862 Closed cycle IC engine HITACHI SHIPBUILDING & ENG CO Ltd 21 March 1973 [14 April 1972 (3) 21 Aug 1972 (3)] 13672/73 Heading F1B [Also in Division F4]  I.C. engine operating on a mixture of oxygen and re-cycled exhaust gas comprises a compressor capable of compressing a volume of gas slightly greater than the volume of exhaust gas produced by the engine when the engine is operating at maximum load, a secondary control valve adapted to return a portion of the compressed gas delivered from the compressor to the circulating working gas system to maintain the working gas pressure at a constant value, the remainder of the compressed gas being discharged to the outside of the engine system and oxygen supply volume control means consisting of a detector to determine the concentration of oxygen in the gas supplied to the engine and means to control an oxygen supply flow control valve in response to the output of the detector to maintain the oxygen concentration at a predetermined level. Exhaust gas from the engine 1 passes through a manifold 3 which forms part of a heat exchanger 17 for the fresh mixture, into a cooler 4 into which water 70 is sprayed, the water and condensate being removed in a separator 6. An amount of gas equal to the amount of carbon dioxide produced by combustion is passed through conduits 7 and 8 to a compressor 9 and discharged through a check-valve 11 against water pressure externally of the engine housing. The remaining gas passes to a mixer 13 where oxygen from a tank 15 is added and enters the engine through a pipe 16. Fuel is supplied from a tank 19 to a fuel pump 20. Stop-valves 25 and 26 open automatically when the engine housing is above the water surface to allow normal aspiration and exhaust respectively. At the same time stop-valves 28 and 30 clos to stop the flow of re-cycled gas and oxygen respectively. The engine can be stopped by closings a fuel valve 33. Part of the compressed gas from the compressor 9 is returned to the engine intake pipe in order to maintain the pressure in the system. The pressure of the returned gas is reduced by two valves 35 and 37 which are controlled by a constant pressure tank 36. The pressure of the oxygen supplied from the tank 15 is kept constant by a valve 38, the amount of oxygen being controlled by a valve 14 which is actuated in response to the output of oxygen detector 39. To avoid delay in the response of the valve, the engine speec and fuel pump rack position are detected and to prevent long-term accumulated errors are combined with the oxygen detector signal to control valve 14. Alternatively the rate of fuel flow may be detected directly by a meter 46. To prevent errors in the oxygen detector the gas contacting the detector is bled off the pipe 16 and cooled and de-watered. Since the specific heat of the carbon dioxide/oxygen mixture supplied to the engine is low, the mixture is heated by the heat exchanger 17. The gas temperature can also be raised when the engine is operating at low load by opening a valve 56 to admit exhaust gas to the intake pipe, the valve being opened in response to engine intake temperature. Alternatively, the valve may be opened wholly or partially in accordance with engine speed and fuel pump control rack position. Again the valve 56 may be controlled in accordance with the degree of thermal expansion of the exhaust pipe. To facilitate starting in the re-cycle condition the proportion of carbon dioxide in the intake mixture is reduced by blowing in compressed air from a tank 58, the air-pressure being regulated by valves 57 and 60. This air can be used to purge the system of exhaus gas by providing a blow off valve 61. To prevent build-up of carbon dioxide, in the mixture supplied to the engine, during warming up, a valve 63 is opened to admit a small continuous supply of compressed air. Instead of air, nitrogen, helium or argon may be used. If the pressure in the engine housing rises above the intake system pressure a valve 66 allows flow into the intake system. The crank-case is vented to the intake manifold through a check-valve 67 which opens at a lower pressure than the valve 66. Exhaust gas cooling and de-watering. Ambient water is admitted through a stop-valve 75 and pressure reducing valve 76 to an engine driven pump 74 which supplies the spray 70. It passes through an engine housing atmosphere cooler 78 and also circulates through the engine cooling system. Water from the separator 6 drains into a tank 71 and is discharged by a pump 80. The water level in the tank 71 is kept constant by a ball-valve 84 which is connected by a pipe 83 to the delivery side of the pump 80. In a modification, Fig. 3, pure water, stored in a tank 71 is pumped through a cooler 88 by pump 86. Sea water is pumped around the cooler by a pump 90. The pure water circulates through the engine 1 and compressor 9 and supplies the spray 70. The cooler may be in the tank 71, or the cooling coils may be in the surrounding water outside the engine housing.