Patent GB-684555-A (GB)
Title: Improvements in or relating to hydraulic pumps or motors
IPC: F16H39/00
Filed: 1945-10-30
Abstract: 684,555. Reciprocating pumps. ORELL, H. Oct. 30, 1945 [Oct. 30, 1944], No. 4821/48. Divided out of 684,551. Class 102 (i) [Also in Groups XXIX and XXXI] In a multi-cylinder hydraulic pump or motor of the type having a ported control surface over which the cylinders move to control the flow of liquid to and from the cylinders and an adjustable member by which motion is imparted to the pistons in the cylinders. the adjustable member is displaceable in one direction to vary the stroke of the pistons and the member is also displacable in a different direction from the former displacement to permit variation of the angular positions of the cylinders corresponding to the dead centres of the pistons relatively to the ports in the control surface independently of the displacement which varies the piston stroke. The displacement of the adjustable member in the different direction may be by hand but it is preferable to provide for automatic adjustment according to stroke, speed, pressure or direction of rotation. In the range of low speed the adjustment may be modified so that an increase or decrease of pressure in the liquid in the cylinder during the change from the suction port to the pressure port or vice versa is automatically diminished. Figs. I and 2 show a hydraulic pump or motor comprising a shaft 9 having disposed at its end a swash plate 8 connected to piston rods 10 of pistons working in a cylinder block 11 controlled by a distributing port block 12. A swash plate carrier 13 and a casing 14 are mounted for tilting movement one relatively to the other. This is effected by spherical surfaces on the member 13 and the casing 14 and by pivoting the casing 14 at 17 in a ring 18 which is pivoted at 19 in a casing 16. A pivot 20 extends beyond the end of the casing 14 the pivot engaging a sliding block movable in a guide 21 of adjustable inclination. The liquid flows to or away from the cylinders through the pivots 17. In a modification a casing corresponding to the casing 14 is mounted in a frame pivoted about a vertical axis and can rotate in this frame in a vertical plane. In another modification, the ring 18 (Fig. 2) is dispensed with and the casing 14 is supported by the shaft 9 which is carried by two ball or roller bearings and by the pivot 20, a further projection on the casing 14 engaging a movable guide whereby the casing may be moved for adjustment. In another modification, the cylinder block is carried by a U-shaped frame pivoted in a casing which has a spherical surface co-operating with a corresponding surface of the gear casing. A slide is provided for adjusting the frame about the pivots and the slide can be tilted by hydraulic jacks. The slide could be used with other embodiments of the invention. The position taken up by the jacks is dependent on the liquid pressure. Fig. 5 shows an arrangement in which the drive from an engine 35 to the wheels of a vehicle includes an hydraulic gear. Adjustment is provided for by means of cardan joints 36, 38, 44, 45 in the shafting 37, 39, 43. The pump 40 of the gear is similar to that shown in Figs. 1 and 2. Fig. 9 shows a modification comprising a radial cylinder pump and radial cylinder motor. The pistons of the pump and motor are operated by tracks 66 the eccentricity of which can be varied by shifting them in a direction at right angles to the plane of the paper. The 'eccentricity can also be varied by raising or lowering the shaft 65 in the plane of the paper by means of a tapered slide 71 which slide is moved in a direction at right angles to the plane of the paper. The adjustments are effected by hand-wheels not shown. In Fig. 12 two hydraulic units 75, 76 which may each be similar to that shown in Fig. 1 are mounted in a common frame which can be rotated about an axis by a hand-wheel, not shown. Stroke adjustment is effected by shifting pins 81, 82 in guide elements 91, 78, as will be understood by reference to the embodiment of Fig. 1 which operates in a similar manner. Pipe connections 79, 80 are provided.