GB940025A - Improvements in hot-gas engines and refrigerators and heat pumps operating on the reversed hot-gas engine cycle - Google Patents

Abstract

940,025. Refrigerating; heat pumps. PHILIPS' GLOEILAMPENFABRIEKEN N.V. Feb. 9, 1960 [Feb. 12, 1959], No. 4550/60. Heading F4H. [Also in Division F1] In a hot gas reciprocating machine, e.g. a refrigerating engine or heat pump operating on the reversed hot gas engine cycle comprising means for controlling the mass of working medium in the working space 1 of the machine the working space being in constant communication with an auxiliary space 25 for containing working medium via a first duct 24 having a fixed resistance to gas flow, the working space also communicates with a space for containing the working medium via a second duct 26 having a variable resistance to gas flow and provided with a valve 28 adapted to occupy closed and open positions in which latter position the resistance to gas flow of the second duct is at least five times lower than the resistance to gas flow of the first duct. The invention is described as applied to a hot gas engine. When the load on the engine is increased so that the speed of the engine decreases the oil pressure in the regulator 29 will increase. Thus the oil pressure urges the medium supply valve 20 into the open position against the action of the spring 32. Via the duet 3 and the duct 7 an amount of medium is supplied to the working space 1. The mean pressure in the cycle then rises which pressure is also attained after a short time in the auxiliary space 25. Thus the speed of the engine which had been reduced by the increased load regains the initial value so that the oil pressure in the regulator 29 drops slightly and the spring 32 is again capable of moving the medium supply valve 20 into closed position. During the temporary increase in oil pressure in the regulator 29 the medium outlet valve 23 is urged more strongly against its seating. Conversely a decrease in load on the engine will involve an increase in engine speed and a corresponding decrease in the oil pressure in the regulator 29 and hence in the ducts 30 and 31. The spring 33 will expand against the lower oil pressure so that the medium outlet valve 23 is moved into open position. Thus an amount of medium will flow out of the working space towards the compressor 15 via the duct 9, the cylinder and the duct 13. The compressor will transfer the medium with little pumping action being required into the container 2 as long as the pressure in the container 2 is lower than the pressure of the medium in the working space 1. Due to the provision of the duct 26 with the valve 28 when the maximum pressure in the cycle is approximately equal to the pressure in the container 2 and the valve 23 is moved to its open position so that the compressor 15 starts pumping medium via the valve 16 and via the duct 17 into the container 2. If the pressure decrease of the medium in cycle is not sufficient to allow the engine to attain its desired speed the spring 33 can expand further owing to the further decrease in oil pressure in the regulator 29 according to the speed of the engine shaft. Thus the valve 28 moves to permit communication between the portions 26a and 26b to a greater or smaller extent. A leak is thus formed to permit flow of working medium from the working space 1. In a displacer piston engine the side of the piston not taking part in the hot gas engine process may constitute a boundary of the auxiliary space 25. The oil pressure regulator 29 may be connected with a centrifugal regulator coupled with the engine shaft. With a multicylinder engine the duct 26 may be arranged between two working spaces. The working medium may be hydrogen. The valve in the second duct may have only two positions, one open and one closed. The clearance between the piston and the cylinder wall may be used as the first duct, the auxiliary space being constituted by the space below the piston.