US2225911A - Hydraulic pump or motor - Google Patents

Description

Dec. 24, 1940.

M. K. INGOLDBY HYDRAULIC PUMP OR MOTOR Filed April 6, 1938 2 Sheets-Sheet l n \KMQ QN QN m &w

MAURICE KERIRNVENTORI INGOLDBY BYM/Wfi 8P2? ATTORN 5Y5 Dec. 1940 M. K. INGOLDBY 2,225,911

HYDRAULIC PUMP OR MOTOR Filed April 6, 193 8 2 Sheets-Sheet 2 INVENTOR:

MAURICE KERR INGOLDBY UNITED STATES PATENT OFFICE HYDRAULIC PULIP OR MOTOR Application April 6, 1938, Serial No. 200,441

In Great Britain October 1, 1937 1 Claim.

This invention relates to hydraulic pumps, motors and other apparatus embodying mechanism of the swashplate type and more particularly to means for controlling the tilting of the swashplate Vin apparatus of that type.

Hitherto it has been the practice in connection with pumps of the swashplate type to control the tilting member or swashplate by means of a series of levers and rods coupled to a pressure 1 operated ram acting against a spring, the ram. the cylinder in which the ram is disposed and spring being arranged externally of the pump casing.

It is the chief object of the invention to provide 15 an improved controlling arrangement for the tiltable member or swashplate which although being particularly adapted for small units may also be adapted for any type of pump, motor or other apparatus employing mechanism of the swashplate type.

' According to the invention the angulation of the tiltable member or swashplate is controlled automatically by means disposed within the casing of the apparatus. Preferably controlling mem- 5 bers are associated with the rotating parts including the swashplate and are adapted to rotate therewith while one or more non-rotating pressure operated elements are disposed within a stationary member, said pressure operated elements 30 being adapted to act on the rotating parts against the action of the control members to vary the inclination of the tiltable member or swashplate according to the pressure conditions prevailing within the pressure system. Preferably, two or 35 more springs or the like are provided each of which is associated at one end with the rotatable swashplate or part associated therewith and at the other with a member which is also adapted to rotate while a plurality of control rams or the 40 like are disposed within a stationary member, said rams being adapted on operation to act in opposition to the springs to vary the angle of inclination of said swashplate. The control rams, of which there may be any desired number, for ex- 45 ample three, are preferably disposed within the normal cylinder block and are adapted to be actuated according to the liquid pressure obtaining in the delivery side of the cylinder block, 1. e. in the pressure system, the motion of the rams 50 being preferably transmitted through a thrust collar and ball race to a rotatable member which in turn is adapted to act on the swashplate.

In order that the said invention may be clearly understood and readily carried into eifect the J5 same will now be more fully described with reference to the accompanying drawings, which show one embod ment by way of example and in-which:

Figure 1 shows partly in section "the relevant parts of a pump embodying the invention.

Figure 2 is a cross sectional view. J

Referring to the drawings, l0 denotes a tiltable member or swashplate which is mounted in known manner on a driven shaft H and is adapted to be tilted from a vertical or no-stroke position indicated in dotted lines into for example the full stroke position shown in full lines or any other intermediate position to effect actuation of a pinrality of pistons such as that indicated at II. The outer ends of the connecting rods such as I3, are supported in known manner in a non-rotatable socket ring H carried by the swashplate I0, while the pistons themselves are adapted to slide in cylinders such as [5 which are formed in a stationary cylinder block or barrel l6 and provided with inlet and outlet ports l5 communicating with a valve chamber notshown. In accordance with the invention two springs ll are associated with the swashplate l0 and are adapted to rotate therewith, said springs being disposed one on either side of the shaft II. The springs ll are associated with guide members l8 which latter are in the embodiment illustrated secured to the rear face of the rotating swashplate ill by means of pins l9 which are anchored in suitable elements 20 formed integrally with or mounted on said swashplate. The mating members 2| at the opposite ends of the springs ll are anchored to a rotating thrust plate 22 by means of similar pins 23 and elements 24. The plate 22 is, as can be seen from the drawings, mounted on the shaft I I and is adapted to rotate therewith and the arrangement is preferably suchthat suitable rollers or other thrust bearing members are interposed in known manner between the rear face of the plate 22 and a stationary part of the casing of the pump. Mounted in suitably disposed cylinders 25 within the cylinder block it are a plurality of rams or the like 26 and in the present embodiment three such rams are provided which are spaced evenly around the block 16. The cylinders 25 in which the rams 26 are disposed are adapted to communicate through the medium of suitable channels or condu ts such as are indicated at 21 in the cylinder block IS with the delivery side of the pump which is in communication with the pressure system so 0 that the rams 26 will be subjected to the pressure of the liquid on the delivery side of the cylinder block, 1. e. the pressure in the pressure system as distinct from the normal pressure existing in the apparatus casing. The rams 28 are adapted when in their operative position to bear against a thrust ring or the like 28 which carries the outer race 29 of a ball bearing, the inner race 30 of which is mounted on a member 3| which is in turn adapted 5 to slide axially on the driven shaft H but is rotatable therewith. The slidable member 3i is as can be seen from the drawings formed with a sleevelike portion 32 adapted to surround the shaft H and to serve as a seat for the inner race 30 of the ball hearing. A flange 33 is formed integrally with the sleeve portion 32 and is adapted to project radially thereof and of the shaft H. Means are also associated with the swash mechanism adapted positively to prevent any rotation thereof and thereby to ensure that no side load will be transmitted to the pistons. As can be seen from Figure 2 such means preferably comprise a yoke or the like 36 which is mounted for universal movement about a fixed point such as for example the apparatus casing by means of a suitable ball connection 31 and is adapted to embrace the socket ring I4, its outer ends being freely journalled on projections 38 formed integrally with said ring. The yoke 36 while preventing rotation of the swash mechanism does not hinder the tilting thereof.

In operation, when the shaft I l is rotating and the swashplate I0 is in the full-stroke position shown in the drawing, liquid will be delivered by the pistons I2, which are reciprocated by the swashplate, through the ports Hi to the delivery side of the pump and also to the channels or conduits 2! in the cylinderblock l6 which communicate with the cylinders 25 housing the rams 26, The external resistance to the flow of liquid from thepump will causethe pressure within the cylinders and the entire pressure system to rise and on reaching a predetermined value the pressure acting on the rams 26 will cause the latter -10 to move forwardly. The movement of the rams results in a forward movement of the thrust ring 28, the ball bearings and the sliding member 3|, which by virtue of the roller contact between the flange 33 and the swashplate Ill causes the latter to tilt against the action ofthe control springs ll towards the vertical or no-stroke position indicated in dotted lines. Should the pressure on the delivery side of the pump be decreased the springs I! will overcome the action of the rains 26 and 50 will again urge the swashplate I0 towards the full stroke position. By virtue of the invention therefore the pump delivery is controlled between maximum and zero within any predetermined limits of pressure. Further it will be appreciated that since rotation of the swash mechanism is positively prevented by virtue of the provision of the yoke 36 no side load will be transmitted to the pistons.

The arrangement above described and illustrated is particularly adapted for use in apparatus which also incorporates any or all of the inventions forming the subject of our co-pending patent applications Nos. 200,437 and 200,440, filed April 6, 1938.

Further while the controlling arrangement according to the invention is also particularly adapted for use in small pumps oi the swashplate type its application is not limited thereto since it may be applied to any pump of the swashplate type and also in certain cases to motors and other units employing swashplate mechanism.

What I claim and desire to secure by Letters Patent of the United States is:

A hydraulic unit operating with a hydraulic pressure system and having a casing, swashplate mechanism including a shaft, a swashplate, a non-rotating cylinder block having a plurality of cylinders therein, and pistons operatively connected to said swashplate and reciprocating in said cylinders, the whole being disposed within said casing, the combination of a plurality of resilient members disposed within said casing on that side of the swashplate remote from the cylinder block while being associated with said swashplate to rotate therewith, a plurality of auxiliary cylinders in said cylinder block open to the pressure prevailing in the hydraulic system of said hydraulic unit, a plurality of rams in addition to said pistons adapted to reciprocate in said auxiliary cylinders, a member rotatable with the shaft and slidable relatively thereto, said member being interposed-between the rams and the swashplate, bearing means therefor including an inner ball race mounted on said member rotating with the shaft, ball bearings, and an outer race with which said rams are adapted to cooperate, and a roller member associated with said swashplate with which said rotatable and slidable member is adapted to cooperate on movement thereof under the action of the rams so that a force will .be transmitted to the swashplate against the action of the resilient members so as to vary the inclination of the swashplate in accordance with the pressure conditions prevailing within said hydraulic pressure system of said hydraulic unit.

MAURICE KERR INGOLDBY.

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