GB663462A - Improvements in and relating to revolving cylinder hydraulic pumps or motors - Google Patents

Abstract

663,462. Hydraulic motors. SHAW & SONS (SALFORD), Ltd., J., and WILLIAMS, T. E. July 1, 1949 [June 2, 1948], No. 14860/49. Class 69 (ii) [Also in Group XXVIII] A bearing, a rotary cylinder band and valve moving as one valve are all arranged close together in the order stated, the barrel and valve moving as one, the inner bearing being a heavy duty precision bearing (defined in the Specification) and means are provided whereby the high pressure liquid exerts a force on the rotary valve to oppose the load of the high pressure liquid on the valve and thereby oppose its tendency to deflect under that load and the tendency of the inner bearing to yield radially under its load. In the hydraulic pump shown in Fig. 1 a revolving cylinder block 6 is located between a precision tapered roller bearing 9 loaded by springs 30 and a parallel roller type bearing 3 a rotary valve being formed as an extension of the rotor shaft at its left-hand end. An auxiliary gear type feed pump 21 supplies oil under pressure preferably through a filter to a part annular inlet port 23 in a bush 10 whose bore may be arranged as regards any initial eccentricity it may have due to imperfections of manufacture so as to take up the most suitable angular position to give minimum leakage of oil with no rubbing action at normal pressure. It is stated that the auxiliary pump could be a vane or impeller type of pump. The pressure oil could be supplied from an outside source. In the case of an engine the gear pump is dispensed with. Surplus oil passes to an outlet not shown and if sufficient back pressure is not created a restriction valve can be fitted to this connection, the valve being spring-loaded and may have its spring load varied as the stroke of the pump is varied less inlet oil pressure being created by the valve as the pump stroke shortens. A part annular balancing recess 23a in the bush 10 is connected to a part annular outlet port 23b, the pressure in this recess creating a load on the shaft in the opposite direction to the load created by hydraulic pressure at the outlet port. Part of the bush may be cut back at 10a to allow of upward deflection of the shaft without rubbing and to allow leakage oil to escape. If the pump is non-reversible the inlet port 23 could be larger than the outlet port 23b. An oil connection 80 serves to direct a portion of the surplus oil from the pump 21 into the track system to lubricate the slippers. The track ring may be drawn out without taking off the inner race of the main bearing 9 and if the coupling at the right-hand end of the pump can be easily slipped off the shaft the complete rotor stroke shortens. A part annular balancing recess 23a in the bush 10 is connected to a part annular outlet port 23b, the pressure in this recess creating a load on the shaft in the opposite direction to the load created by hydraulic pressure at the outlet port. Part of the bush may be cut back at 10a to allow of upward deflection of the shaft without rubbing and to allow leakage oil to escape. If the pump is non-reversible the inlet port 23 could be larger than the outlet port 23b. An oil connection 80 serves to direct a portion of the surplus oil from the pump 21 into the track system to lubricate the slippers. The track ring may be drawn out without taking off the inner race of the main bearing 9 and if the coupling at the right-hand end of the pump can be easily slipped off the shaft the complete rotor can be withdrawn from the casing at the valve end without disturbing the casing 1. Instead of tapered bearings other suitable types may be employed. A pressure actuated support may be on both sides of the inlet port. The stroke is adjustable by varying the eccentricity of track rings 14 with respect to the cylinder block. When an end cover is taken off, springs 30 push a ring 32 up against the roller bearing 3. The pistons may be operated by cams. A modification is described in which the balancing area is between the port 23 and the bearing 9, and a part annular slipper bearing is urged up against the valve shaft by a plunger loaded by the outlet pressure. This corrects the deflection of the valve shaft so that efficient working of the rotary valve is obtained with a minimum running clearance and hence leakage and slip. Shock can be eliminated by putting the lap more onto the suction side particularly at that end of the part annular port where the pistons commence the suction stroke so that the cylinder port in the rotary valve shaft cuts off from the outlet port on or about dead centre of the piston stroke. In Figs. 6 and 7, Fig. 7 being a section on the line 7-7 of Fig. 6, the load on the tapered bearing 9 is produced partly by straight or curved surfaces 42 on the track rings partly by the force exerted by springs 46a (Fig. 7) in recesses in a part annular ring 46, and partly by liquid pressure acting on the ends of plungers 49 which bear upon the ring 46 which transmits thrust to the rotor through a ball thrust washer 47. The counterbalance area is replaced by a slipper bearing 34 loaded by a plunger acted upon by the pressure in the outlet port. Fig. 8 shows a swash plate type liquid pressure engine. The thrust of the pistons 53 is partly counterbalanced by two or more compression springs 76 and two or more small hydraulic plungers 77. A plunger 72 is provided to exert a thrust on a ring 71 contrary to the valve load. Bronze rings 66a are provided between the rotor and a ring 66 which houses one end of a spring 63, which spring exerts an initial load on the main bearing. In a modification having a main bearing of the twin parallel roller type with a tapered inner race which may be expanded by being forced up its tapered seat formed on the rotor extension, the valve ports are formed in a sleeve the ports being cut right through except where bridges are left joining the sides of the ports together for strength purposes. The sleeve is mounted in a separate cover attached to the usual cover 8. Springs may protrude from the inside of the right hand side end cover with an inclined hydraulic plunger pushing on the outer race of a ball bearing, the main bearing thrust load being over-counteracted and some of the radial load being relieved off the driving end bearing. In another modification an extension of the valve end of the shaft is fitted with suitable gearing which drives a vertical depending shaft which passes down inside a depending tube, the tube having the auxiliary feed pump for example of the impeller type mounted on its lower end. The pump may be reversible. Specification 430,849 is referred to. The Provisional Specification describes embodiments of the invention which differ in detail from those of the Complete Specification and refers to certain modifications. Two tapered bearings could be employed adjusted by a ring screwed into the outer end of a cover plate or a third tapered bearing could be fitted to support the outer valve end of the rotor. Other detail modifications are referred to.