Improvements in arrangements for regulating reciprocating steam engines having rotary-cam-controlled valve gears with poppet valves

摘要

745,375. Governors; engine valve and stop-gear. KURETSCHKA, F. Jan. 13, 1953 [Feb. 6, 1952], No. 982/53. Classes 57, 122(2) and 122(4) A governor 2 regulates the speed of a reciprocating steam engine by axially displacing a cam 4 to alter the admission period of an inlet valve controlled by the cam, the relationship between the axial displacement of the cam 4 and the alteration of the admission period being non-linear. The governor 2 is mounted on a shaft 1 driven by the engine crankshaft and connected by bevel gears 6 7 to a cam shaft 3 carrying the cam 4 which oscillates a follower 16 mounted on a second-order lever in operative engagement with the rod of the inlet valve. When the engine is running at low speed the inlet valve is held open for a relatively long period by the profile at F while an increase in engine speed causes the governor to act through a lever 13, 14 to displace the cam shaft to the right so that the inlet valve is held open for a shorter period by a profile such as C. Toprevent the engine running at excessive speed, the .left-hand portion of the cam 4 has a circular profile which does not open the inlet' valve at all. The time at which this valve opens remains unchanged with the axial position of the cam while the time at which it closes is varied non- linearly as shown by the lines 23b, 23c to provide a variation in the sensitivity of regulation over the speed range of the engine. Engine stop-gear. If the engine speed rises beyond its permitted maximum, for example as a result of sudden removal of the load, the governor 2 causes a striker 24 to rock a two-armed lever 26 anticlockwise and release a weight 28 which closes a valve 30 in the steam supply pipe.