Patent GB-191118464-A (GB)
Title: Improvements in Operating Gear for Internal Combustion Pumps and Compressors.
Inventor: HUMPHREY HERBERT ALFRED
Filed: 1911-08-15
Granted: 1912-08-15
Abstract: 18,464. Humphrey, H. A., Rusdell, W. J., and North, O. D. Aug. 15. Direct explosion apparatus. - Comprises a method of controlling the valves of internalcombustion pumps for liquids or elastic fluids operating without a fly-wheel but having suitably heavy reciprocating masses, such as are described in Specifications 20,736/06, 18,594/07, 18,595/07, 19,341/07, 22,646/07, 15,820/10, 11,818/11, and 28,187/11, [Class 8(i), Air and gases, Compressing &c.], wherein cyclical changes of pressure or velocity or position of a moving part operate a device which controls pressure changes transmitted by fluid to control the valves substantially without change in volume of the transmitting - medium. Fig. 1 shows the invention applied to a fluid-controlled locking-gear for regulating the action of the valves of a four-stroke-cycle pump in the manner described in the above-mentioned Specifications. At the completion of the explosion or expansion stroke, the exhaust valves 2 and scavenging- valve 4 are open as shown in the Figure, and the admission valve is locked shut by means of a piston b controlled by fluid transmission from a piston 19, which at the same time controls the piston a adapted to lock the valves 2, 4 at the proper intervals. At the termination of the first return or exhaust stroke, the valves 2, 4 shut in the usual manner, and the increase of pressure in the combustion chamber due to the compression of a cushion of gas in the top thereof is transmitted through a pipe 6 and valve 7 to the right-hand side of a piston 9, which is forced to the left, carrying with it the piston 19 and thus locking the valves 2, 4 by means of the pistons a and withdrawing the piston b so that the admission valve is free to open. At the same time. a spring 13 is compressed, tending to reverse the position of the valve 7, but movement of the valve is prevented by friction due to end pressure thereon. The admission stroke then occurs, drawing in a fresh charge through the valve 3, and as soon as the pressure falls in the combustion chamber, the spring 13 reverses the valve 7. Finally, the second return or compression stroke occurs and the increase of pressure causes the pistons 9, 19 to move to the right again, locking the valve 3 and setting the valves 2, 4 free to open as soon as the gases have expanded to atmospheric pressure. Fig. 2 shows a similar device adapted to operate the valves directly and independently of the pressure within the combustion chamber. In this case, liquid under pressure is stored in an air-vessel 22 having a non-return valve 23, and is admitted to operate the pistons controlling the valves by a four-way valve 7, which is periodically rotated through 90 degrees by a spring-controlled piston 9. The pressure on the low-pressure side of the valve 7 is that of the head of liquid in a pipe 27 and tank 28. When it is desired that the exhaust valve 2 shall open at a pressure above atmospheric, a spring-controlled piston device 33, 35 is interposed in the pipe 38 leading to the valve 2, which operates as follows. During the earlier portion of the explosion stroke, the piston 35 is forced to the extreme right, but as the pressure falls, it moves slowly to the left, and, when the groove 37 comes opposite the pipe 38, pressure fluid is admitted to operate the valve 2. At the other period of the cycle at which the groove 37 passes the pipe 38, the pressure on the inner face of the valve 2 is sufficiently great to prevent it from opening. The following modifications and details are described : (1) The locking-pistons on the valve stems, Fig. 2, may be separate from the stems and arranged to prevent leakage. (2) Dash-pots may be fitted to prevent too sudden closing or opening of the valves. (3) The rotary valve 7, Fig. 2, may be replaced by a multiple slide valve having similar functions. (4) When applied to a two-strokecycle pump the inlet valves only may be controlled hydraulically, and the four-way valve, which may be actuated by a flap or vane in the combustion chamber, may serve to admit pressure fluid to a piston and cylinder operating a gas bell for forcing in the fresh charge at the proper moment. (5) When a float piston with a spring buffer to check its downward movement is employed, the reduction of pressure below the piston at the moment when it is checked by the buffer may be utilized to open the exhaust valves by a hydraulic transmission device. (6) In a two-stroke-cycle pump, the fluidpressure valve for operating the admission valves may be controlled by the position of the air bell supplying the air for combustion. (7) The changes in pressure in an air-compressing chamber or in a pressure-intensifying chamber at the end of the play pipe may be utilized to operate the fluid-pressure valves for controlling the admission and exhaust valves. (8) The exhaust valves may be controlled by fluidpressure devices operated by a vane in the play pipe or other suitable position, the arrangement being such that, in the case of a four-strokecycle pump, the vane is prevented from operating during the small outflow accompanying the admission stroke. (9) In a two-strokecycle pump, the admission valve may be controlled by a fluid-pressure device dependent upon the changes of pressure in the intensifier chamber or air-vessel at the end of the play pipe in such a manner that the admission valve is opened at any desired moment while the pressure is falling in the intensifier chamber on the return stroke, thus limiting the volume of charge introduced. (10) The volume of charge in a four - stroke - cycle pump may be similarly limited by causing a gas bag or similar gas-measuring device to control a fluid-pressure valve which causes the admission valve to shut when a definite volume of gas'has been introduced.