Patent GB-774609-A (GB)
Title: Improvements in or relating to combined starting and relief valves for internal combustion engines
IPC: F02N9/04
Filed: 1955-03-08
Abstract: 774,609. Starting; valves. LAMB, J. and LAMB PUBLICATIONS & INVENTIONS Ltd., J. Aug. 31, 1955 [March 8, 1955], No. 6780/55. Classes 7 (2), 7 (5) and 7 (6). In an engine having a single valve opening in each cylinder 6, Fig. 1, to receive a combined starting and relief (CSR) valve adapted to admit pressure air to the cylinder for starting purposes and to release excess pressure during normal working, each of the valves is normally held on its seat by loading air pressure. The (CSR) valve for a single cylinder or opposed piston diesel engine comprises a lower part 1, mounted in the cylinder head 2, a middle part 3, and an upper part 4; the part 1, which opens via a passage 5 into the cylinder 6, communicates with the bore 8 of a starting valve 7 that has a flange 9 forming a seating for a spring 10, the valve 7 normally sealing off the passage 5 from a starting air inlet port 11. The top of the bore 8 is closed by a cylinder relief valve 12 into which projects a pin 15 that extends upwardly into a chamber 17 which houses bellows 18 ; an outlet port 24 and an inlet port 25 are provided in the part 4. The starting and relief valves 7 and 12 are held on their seats by compressed air flowing through the port 25 and into the bellows 18, and additional pressure being exerted on the starting valve 7 by the spring 10 and the arrangement being such that the valve 12 lifts to relieve compression or excess pressure without unseating the starting valve 7. The pressure within the bellows is reduced to atmospheric while the starting valve is required to admit air from the port 11 into the cylinder 6 ; the starting air acts under a flange 9 to open the valve 17. In a modification, the starting valve is extended to the cylinder end of the part 1 so that the passage 5 is formed in this extension. In a further modification, the starting valve is of the outwardly opening type and is unseated by admitting starting air behind a piston in the bellows compartment, the bellows operating the relief valve alone. The cylinder end of the starting valve may be cooled by supercharging a scavenging air. CONTROLLING MECHANISM (a) General Each cylinder of a six-cylinder engine has a valve CSR<SP>1</SP>-CSR<SP>2</SP>, Fig. 2, as in Fig. 1, only three such valves being shown, and upon opening control valves 29, 30 compressed air flows from a container 26 to both a relay valve 27 and a reducing valve 28, which latter is in communication with a control box 34. Upon moving a starting lever 35 from the " stop " position, wherein the cylinders are decompressed, towards the " start " position air passes from the control box 34 to a distributer 37, and at the same time traverses both a pipe 38 to open the relay valve 27 and a further pipe 39 to close an airloaded safety valve 40. The distributer 37 incorporates sets of valves 41 one to each CSR valve, that are operated from an auxiliary cam-shaft 44 driven by the engine cam-shaft 42, and air will pass those valves 41 that are open and flow along pipes 43<SP>1</SP>-43<SP>3</SP> to enter the bellows of the associated CSR valve and prevent starting air from entering the cylinder connected thereto ; the remaining valves 41 will be closed thus preventing air from reaching the bellows of the corresponding CSR valves and thereby allowing air to be admitted to the related cylinder via a pipe 31 and the relay valve 27. As the engine rotates the valves 41 will open and close sequentially thus controlling the supply and cut-off the starting air to the various cylinders. Since the bellows are not supplied with air when the starting lever is moved into the " stop " position, the opening and closing of the relief valve part of the CSR valves during the compression and exhaust strokes will bring about a braking effect and rapidly stop the engine, the relief valves also facilitate turning over of the engine by auxiliary power during overhauls. Where CSR valves are used in which the starting valves are piston operated the arrangement is modified to effect control of the additional supply of air to the starting valve pistons, the relief . valves being continuously loaded except when the starting lever is in the " stop position. (b) Control box The box 34 is divided into distributer and relay control sections each of which contains an inlet valve 47, Fig. 4, and an exhaust valve 48 ; each pair of valves is operated by a separate cam 49 on a shaft 51 which is angularly displaced through 90 degrees upon actuation of the starting lever. The valves in the distributer section operate earlier than those in the relay control section so that with the starting lever in the " stop " position both inlet valves are closed and both exhaust valves open whilst the " start " position of the lever the valves are in the reversed positions: with the lever at the " on fuel " position, the inlet and exhaust valves in the relay control section are shut and open, respectively, the corresponding valves in the distributer section being in the reverse positions. (c) Starting air distributer Each set of distributer valves 41, Fig. 2, which comprises an inlet and exhaust valve 59, 60, Fig. 9, for each engine cylinder, is disposed in a casting 61 through which passes the auxiliary cam-shaft 44. When the engine is normally working the inlet valves 59 are open and the exhaust valves 60 are closed, the valves being maintained in this position because the operating mechanism 63 has been disengaged by clockwise rotation of a lay shaft 64 connected to the starting lever ; when the latter is put in the " start " position the shaft 64 is rotated anti-clockwise through 15 degrees and if a particular piston is not in a starting position the exhaust valve 60 will remain closed and the inlet valve 59 will open allowing compressed air to enter the bellows of the associated CSR valve. Immediately afterwards air is released to the relay control section of the control box 34, Fig. 2. If the particular engine piston is in a starting position then the inlet valve 59 remains closed and the exhaust valve 60 would have opened, upon engagement of the operating mechanism 63, thus opening the CSR valve bellows to atmosphere and allowing the admission of starting air to that cylinder. Upon the piston passing out of the starting position the air is cut off by the revolving cam 65 opening the inlet valve 59. Each valve 59 and 60 is actuated by one of two cams 65, one being for " ahead " and the other for " astern " running, the auxiliary cam-shaft 44 being axially movable to reverse the direction of rotation ; the mechanism 63 had an " ahead ", an " astern " and a " disengaged " position. With two-stroke engines additional equipment is required to inject fuel at the correct time whilst with four-stroke engines it is also necessary to provide inlet and exhaust valve operating means for both directions of rotation.