Patent GB-430042-A (GB)
Title: Improvements in or relating to the starting of internal combustion air compressors
IPC: F01L13/00
Filed: 1934-01-20
Abstract: 430,042. Starting. PESCARA, R. P., 115, Rue de la Tour, Paris. Jan. 20, 1934, No. 2104. Convention date, Jan. 20, 1933. [Class 7 (v)] [See also Group XXVIII] In an arrangement for starting internalcombustion air compressors having one or more freely moving pistons A and chambers 2 which serve during normal running for cushioning the pistons, an auxiliary reservoir 3 for air or gas having a pressure greater than that reached in the chamber 2 during normal running is connected to the chamber 2 for starting, and a regulating device is provided which causes the pressure in the chamber 2 to fall gradually to its normal value as the delivery pressure of the compressor increases. The reservoir 3 is of relatively large capacity, so that the pressure of the starting fluid is not substantially varied by the movement of the piston in the cushioning chamber. As shown in Fig. 1, the piston A reciprocates in a combustion cylinder 1, a compressor cylinder B, and the cushioning chamber 2, which is connected to the reservoir 3 through a conduit provided with a valve 9 normally closed by a spring 10. A three-way cock 4 is arranged to connect a compressed-air supply pipe 5 first to the reservoir 3, in order to charge it, and then to the space behind a piston 8 on the stem of the valve 9, in order to admit the compressed air to each of the chambers 2 for starting. The pressure of the air supplied to the reservoir 3 is considerably higher than the normal pressure at which air is delivered to the main reservoir 11 by the compressor. In order to reduce the pressure in the chamber 2 gradually as the delivery pressure of the compressor increases to its normal value, a valve structure is inserted between conduits 12, 13 connected respectively to the reservoirs 3, 11. The valve structure comprises a piston valve 14 closed by a spring 15, the stem of the valve carrying a stepped piston 16, 17 working in cylinders connected by pipes 18, 19 to the space 2 and to the outlet of the compressor. As the valve 14 is gradually opened by the increasing delivery pressure of the compressor, air from the reservoir 3 flows to the reservoir 11 to equalize the pressures. In a modification, Fig. 2, the compressor comprises stepped pistons each working in low-pressure and high-pressure cylinders B<1>, B<2>, and a check valve 20 is inserted between the reservoir 3 and an enclosing chamber 22 connected to the outlet 12<a> from the highpressure cylinder, so that the compressed air is discharged through the reservoir 3, chamber 2 and conduits 12, 13 to the reservoir 11. The piston valve 14 between the conduits 12, 13 is fitted with a piston 23-25 of three diameters movable in cylinders connected respectively to the chamber 22, to a reservoir 33 fed by the low-pressure cylinders, and to the conduit 12. During the starting period, the air outlet from the low-pressure cylinders is throttled by a sliding-disc valve 34 connected to a piston 36 in a cylinder connected to the reservoir 33, the pressure in which opens the valve against the tension of a spring 35. In a further modification, Fig. 10, to enable air remaining in chambers 2, 3, 33 and the high-pressure cylinders B<2> to be utilized for bringing the pistons into starting position, a check valve 42 is adapted to connect the chambers 44 of the low-pressure cylinders with a chamber 45 connected through conduits 46, 12 with the chambers 2 and through a check valve 47 with the high-pressure cylinders B<2>. The valve 42 is provided with a piston actuated by compressed air from a pipe 54 fitted with a cock 55, or from the main airsupply pipe. Similarly actuated valves 49, 53, 20 are arranged respectively to relieve pressure in the low-pressure cylinders B<1> and chambers 44 until the pistons are near their extreme outer positions, to cut off the chamber 51 from the motor cylinder 1, and to cut off the chamber 3 from the reservoir 22, during starting. The valve 14, Fig. 2, may be replaced by a piston valve 30, Fig. 7, controlled by the stepped piston 23-25. The conduit 12 opens into a chamber 28 directly beneath the small piston 23, and the cylinders of the piston elements 24, 25 are connected through tubes 19, 26 with the outlets of the low-pressure and high-pressure compression cylinders respectively. The valve 30 is normally kept in the closed position by a spring 31 and by an external pressure acting on a piston 32 connected to the valve 30. A spring 15 acting on the piston 23-25 is adjustable by means of a screw 27 to enable the time at which the piston is lifted to be adjusted. In a further modification, Fig. 8, the outlet valves of the compression cylinder and a chamber 37 connected with the intermediate chamber 33, Fig. 2, can be placed into or out of communication by a piston valve 38, the lateral walls of which are subjected to the delivery pressure. The valve is held on its seat by a spring 41, and the inner part of the seat is connected with the chamber 37. When air is delivered by the compression cylinder, it leaks through calibrated orifices 39 into the chamber 37 until it is sufficient for progressively lifting the valve 38 against the spring 41.