Patent GB-491729-A (GB)
Title: Improvements relating to valve gears for steam and other reversible engines
IPC: F01L31/16
Filed: 1937-03-11
Abstract: 491,729. Valve-gear for fluid-pressure reciprocation engines. REIDINGER, A. March 11, 1937, No. 7159. [Class 122 (ii)] Comprises cam-actuated valve-gearing wherein the admission or exhaust events in a cylinder are controlled by a valve which is under the differential control of a pair of cams, means being provided whereby either cam may be adjusted in relation to the piston stroke independently of the other cam or of the reversing- gear or other controlling means for the other valve. Four hollow cam shafts 1-4 are arranged in pairs in a casing 5. Shafts 1, 3 carry cams for controlling the exhaust as, e.g. described in Specification 413,708. Shafts 2, 4 carry cams controlling the admission. Shafts 3, 4 open the valves ; shafts 1, 2 control closure. Separate cams control the valve events for the two directions of running. Cams 6, 7 control forward and reverse lead; cams 8, 9 control cut off; cams 10, 11 control forward and reverse release, and cams 12, 13 control compression. Followers are shown at 14..17 respectively. The cam shafts are moved in a cage including sliding bearings 18, 19, 20, and are driven by a spiral gear wheel which meshes with teeth on a casing 22. The casing carries pinions 23, 24, and gears with teeth on a casing 25 provided with bevel wheels 26, 27. The pinions 23, 24 engage wheels 28, 29. Wheel 28 engages shaft 4 which is splined at its other end to a sleeve 31 in bearing 19 which sleeve drives shaft 3. Shafts 1, 3 are connected by gears 32, 33. The pinions 26, 27 engage wheels 34, 35. Wheel 34 is splined to shaft 2. The hub portion of wheel 35 carries a spur wheel 38 which engages a sector 39 on a shaft 40 and also a toothed sector 41 of larger radius fixed on the end of the hub portion of the wheel 29. Rotation of the shaft 40 varies the angular relationship between the cam shafts and the crank of the engine. Sector 41 gives greater cut-off variation. The cams are independently adjustable. Each cam shaft is provided with sets of right- and left-hand helical splines of equal pitch 42. The forward and reverse cams are internally threaded right- and left-handed respectively to engage the splines. Axial cam movements relative to their shafts are effected by internal screw members. A forward adjustment is accompanied by a corresponding backward adjustment through screw-threaded bars 43, 47, 49, 50 operated directly or from the engine-driver's cab. The cut-off cams 8, 9 may be fast on their shafts, and only varied by rotating shaft 40. The reversing-shaft 51 operates shaft 40 by wheels 52, 53. A wheel 54 on shaft 51 operates the cage 57 by teeth 56 thereon. Blank spaces 58, 59, 60 on the wheel and rack permit cut-off adjustment. After the shaft 51 is rotated 110‹ for reducing cut-off, teeth 55 engage teeth 56 and the cage is moved to the left for early backward cut-off. The valves remain closed when the followers engage intermediate positions 61. Profiles may be provided to provide byepass conditions, with all valves open, or only the admission or exhaust valves open. Followers are arranged on both sides of the gear, Fig. 1, for the two ends of a cylinder. The sector 39 may be interrupted corresponding to the engagement of the teeth 55, 56 to avoid cam adjustment during reversal. A form of rotating cam gear is described wherein each valve is controlled by the differential action of a pair of cams whose functions are changed during reversal. Four cams, Fig. 5 (not shown), are provided all mounted on a single cam shaft. The forward cut-off cams control lead during reversal. Similarly the exhaust cams change their function. The cams are loosely mounted upon sleeves loosely mounted on the cam shaft. They have side teeth which through intermediate, independently-adjustable members, Figs. 6-8 (not shown), with face teeth on either side, engage tooth members which carry dogs engaging grooves in the cam shaft. The various elements are locked with their teeth in engagement by screwed sleeves engaging the cams. The cam shafts are axially adjusted by rack and pinion and rotated by worm-gearing.