US2396316A - Hydraulic pump or motor - Google Patents

Description

March 12, 1946. H. L. CHISHOLM. JR

HYDRAULIC PUMP OR MOTOR Filed April 2 1942 r '3 Sheets-Sheet l at flneer Z. 619181-104, de.

March 12, 1946. g s g JR I 2,396,316

HYDRAULIC PUMP OR MOTOR Filed April 2, 1942 3 Sheets-Sheet 2 v 'fjs fimee/ A. Ola/104M, de-

3 Sh ets-Speet 5 MN N 3 \i Q E H. CHISHOLM; JR

HYDRAUL IC PUMP 0R MOTOR Filed April 2, 1942 March 12, 1946.

Fly 5 1 Z :71 fin er L. CHIJH'OLM, (/2.

;in holding the blades against the rotor.

Patented Mai-.12, 194$ UNITED v STATE nrnnnmc mm? on MOTQR j Harry L. Chisholm, Jr., .Buflalo, N. Y., assignor io Houdaille-Herahey Corporation, Detroit, Mich, a corporation of Michigan Application April 2, 1942, Serial No. 437,834 3' Claims. (01'. 1 03-123) My invention relates to hydraulic devices, particularly of the rotary'type, which can be operated with equal efiiciency to function as a pump or as amptor. The invention concerns particularly rotary hydraulic structures such as the type disclosed in Bliss Patent No. 2, dated February 3, 1942, or as disclosed in the copending application of Magrum and Chisholm, Serial No. 398,246, filed June 16, 1941. In this type of hydraulic structure, one or more rotors of generally elliptical shape define with cylinder walls crescent-shaped working chambers connectable with fluid inlets and outlets, and with blades engaging the outer surfaces of the rotors and disposed between the inlets and outlets for directing the fluid flow through the structure.

Spring means are usually provided for holding the blades againstthe rotors, and,in some prior art arrangements, the blades are sub- .iected at their outer ends to the full pressure of the fluid flow, for assisting the spring means Such arrangement obviously creates undue friction between the blades and the rotors, which friction increases with the fluid pressure and will materially cut down the output eflociency of the hydraulic structure whether operating as a pump or a motor. 2

The important object of my invention is to more effectively and efliciently control the operation of the blades and their engagement with the rotors sothat the pressure engagement of the blades with the rotors will be substantially constant under-all pressures of the fluid flow through the structure and with minimum friction, but with the blades at all times intimately held against the rotors to prevent leakage. This eiflcient control I preferably accomplish by subiecting the blades to fluid pressure at their outer ends Just suflicient to counteract the-fluid pressure tending to unseat the blades, or slightly greater than the unseating pressure, so that the spring means may then function alone, or with the assistance of sufflcient pressure, to hold the blades seated against the rotors with the same pressure under all conditions of fiow' through the structure, and with minimum friction, s'o as to avoid loss of energy and efficiency particularly during starting of the structure as 3 Pump or motor.

' My improved structure and control is embodied in the accompanying drawings, in which:

Figure i is a cross section on plane I--I of Figure}; c

1 form the pump cylinders.

- block it.

Figure 2 is a section on plane 11-11 of Figure 1;

Figure 3. is a section on plane Ill-III of Figure 1;

Figure 4 is an enlarged side view of one of the-blades, partly in section; and

Figure 5 is a section on plane V-V of Figure 4.

Briefly describing the structure shown, its housing comprises the cylindrical wall It having the inner end wall or head ll integral therewith, the outer end of the housing receiving the outer end wall or head l2. Fitting into the wall ill and seating against the head Ii is the cylindrical block i3 between which and the outer head it are clamped the various'elements which A drive shaft H extends into the housing and is journalled in ball bearings i5 and is supported respectively by the block it and the headl2, theshaft extending outwardly from the head ii for connection with a driving source such as an electric motor when the structure is to be driven as a pump, or for V connection with mechanisms to be driven when the structure is operated as a hydraulic motor. A fitting i1 receives the shaft and is secured. as by bolts i8, to the head H, and may serve as a bracket for supporting the structure. The fittingll engages a washer l9 for compressing packing 20 around the shaft to prevent leakage.

The finger spring I9 is clamped at its outer periphery between the bracket i1 and the head ii,

but is free therefrom inwardly to bear against the washer it for application of pressure onthe packing, thus assuring automatic take-up for wear or deflection.

The pump cylinder forming elements arerings and plates clamped together between the head It and the block i3 by a clamping ring 2| having threaded engagement in the open end'of the housing wall I0 and abutting the flange 22 of the head i2. As shown, there are two rings 23 and 24, an inner plate '25, an intermediate plate 26, and an-outer plate 21, the outer diameter of the rings and the plates being such that they will flt snugly in the cylindrical bore of the wall It, the plates and rings being held against rotational displacement by dowel pins 66 extending therethrough and anchored in the The rings and plates define annular cylindrical spaces 28 and 29 into which the rotor elements Stand 3| extend ior rotation with the shaft H to which they are secured as by keys 32.

The rotor elements and SI are of generally elliptical shape so as to define, with the cylinder space walls, crescent-shaped working chambers.

1 with a source of fluid such as oil.

D connected with the outlet 88.

The two rotors are displaced 90 on the shaft I4, so that the opposite working chambers 38 and 34 between the rotor 30 and ring 23 will have their maximum volumetric displacement when the working chambers 35 and 38 between the rotor SI and ring 24 have their minimum volumetric displacement. i

The block i3 is cored to provide an annular suction or intake space S (Fig. 3 and dotted lines Fig. l) which communicates with the inlet 37 on the wall l and is connected by suitable piping By independent coring, the block 03 has the segmental discharge space D (Fig. 3 and dot=dash lines Fig. l) communicating with the outlet 38 on the wall It connectable by suitable piping with hydraulic devices for receiving fluid under pressure when the structure is operated as a pump.

For the cylinder spaces 28 and 29, in which the rotors operate, diametrically opposite fluid inlet passageways s and s and diametrically opposite discharge passageways d and d are provided. To form I these passageways, the rings 23 and 24 have transverse bores ti therethrough which align with the transverse bores-42 in the s and s communicate through passages S extending from the inlet space S which communi-. cates with the inlet 31. The passageways d and d communicate with the cylinder spaces through ports 40 and 40' and are in communication through the passages D with the discharge space The rings 23 and 24 are each provided with diametrically opposite blades 43 and 43' for co-. operating with the rotors surrounded by the rings, the blades operating in radially extendbetweeni the plugand a collar 48 on the stem and tending to hold the stem inwardly for pressure engagement with the blade to hold it against the surface of the respective rotor.

The blade is of rectangular cross section and, as shown on Figures 1, 4, and 5, its lower end s sloped transversely to present the inclined surrace '50 extending from one side of the blade to the other to provide a contact tip II which is transversely rounded so that the contact line of the blade with the rotor will be a short distance inwardly from the side of the blade adjacent to thetip. The blades are mounted in their guide slots It with their inclined end surface 50 at one side of the contact line exposed to the flow through the passageways 'd' and (1', while thesmaller 'area 50' at the opposite side of the contact line is exposed to theflow through the passageways s and s, the flow through the passageways d and d'" being the high pressure whether the structure is operating as a pump or a motor, while the now through the passageways s and s isalways at lower pressure.

aseasio perfect contact with the rotors so as to avoid leakage oi fluid directly from the high pressure to the low pressure side, but at the same time the pressure holding the blades against the rotors should be kept constant and with minimum friction between the blades and the rotors. I preferably accomplish this by subjecting the blades to fluid pressure which will counteract the 7 pressure against the surfaces 50 of the blades, such counteracting pressure being at all times the same pensquare inch as that of the pressure against the surfaces 50. As shown, the counter-. acting pressure isobtained by means of one or more passageways 52 through the blades through which the fluid may flow into the blade chain bers as for engagement with the outer ends of the blades. I have shown two such passageways 52 at opposite sides of the longitudinal center line 0! the blade so as to balance the inertia force of the blade longitudinally thereof. While the structure is in operation, the blade is subjected at both ends to the fluid 'at the same pressure per square inchyand by propo-rtioning the available pressure area on the outer end of the blade relative to the available pressure area at the surface 50 at the inner end of the blade, the pressure against the inner and tending to shift the blade outwardly may be entirely neutralized so that the spring 48 will alone function to hold the blade seated, or the counteracting pressure may be in excess of that required for neutralizing the pressure against the surface 50 so that the counteracting pressure will assist the spring 48 in. keeping the blade seated. For example, the surface it exposed to low pressure at one side of the blade contact line could be of such area relative to the surface Elli that the area at the inner end of the blade exposed to the high pressure would be less than the area at the outer end of the blade, so that the difierential fluid pressure would assist the spring in holding the blade seated. Thus, by equalizing the fluid pressure sheet on the ends of the blade, or by differentiating the pressure effect the blade. spring may function alone, or in conjunction with fluid pressure, to control the accurate seating of the blades against the respective rotor under minimum friction at all times. Where the differential pressure assists the spring, this difierential pressure will keep in step with the varying pressure in the passageways d and d in the mechanism, and no matter to what extent this pressure increases, the diiierential pressure will correspond and will assist the spring in keeping the 65 blades properly seated against the rotor. In order to keep the pressure balanced in the outer ends of adjacent blade chambers 44, such chambers may be connected together through passageway 53 provided in the intermediate plate 26. '60 My improved control of the blades will be equallyefliclent whether the structure is oper-'- ated as apump or as a hydraulic motor. When operatedas a pump, the fluid will be drawn through the inlet 31 into the inlet space S in Q the block I: from where it is drawn through the inlet passages s and 8 into the pump chambers v for discharge through the outlet passageways d a and a and the blade ends are :subiected to the pressure of this fluid for operation in the ,will act as collectors for pressure leakage past the sides of the rotors, which leakage fluid flows through vent grooves 11 and v in the outer faces of the plates 25 and 21 for reception in the low pressure passageways s and s.

I have thusproduced'a rotary hydraulic device of the. type described in which the blades, under spring pressure and differential fluid pressure against its ends, are accurately controlled for erfect sealing contact withthe rotors and with friction reduced to a minimum so that the structure may be operated with equally high efllciency as a'pump or as a motor under all conditions of operation. a

. I do not desire to be limited to the exact construction, arrangement, and operation shown and described, as changes and modifications may be made without departing from the scope of the invention.

I claim as follows:

1. A hydraulic rotary structure of the type described comprising a housing defining a cylinder space, a rotor within said space shaped to cooperate with the cylinder space wall to define a working chamber, ports for said working chamber connected with the exterior of said housing, one of said ports adapted to receive fluid under high pressure and the other port adapted to receive fluid under low pressure, an abutment blade in the form of a rectangular plate between said ports engageable at its inner end with said rotor and extending radially outwardly relative to said rotor and in the plane of the rotor axis, said housing having a rectangular guide slot in which said blade has sliding bearing flt, said blade at its inner end having a contact edge adjacent to and parallel with one side thereof and providing the sole contact area for engaging the rotor, said blade end at one side of said edge being sloped or beveled to present an unvarying sloping surface to the pressure of the fluid flow through they high pressure port, means for subjecting the outer end of said blade to the pressure of the high pressure flow, said sloping surface being at, a small acute angle with the rotor surface engaged by'said edge whereby the high pressure fluid will exert against the blade a wedging action having a minimum lateral component and amaximum longitudinal component tending to shift it outwardly in said slot against the high pressure exerted inwardly against the outer end of the blade, the area of said sloping surface being so proportioned to the area at the outer end of the blade exposed to the high pressure that the pressure against the outer end may counteract to apredetermined degree the outward pressure against said surface for holding the blade seated with its contact edge against the rotorunder all conditions of operation of the structure.

, 2. A hydraulic rotary structure of the type described comprising a housing deflhing-a cylinder space, a rotor within said space shaped to cooperate with the cylinder space wall to define a working chamber, ports for said working chamber connected with the exterior of said housing, one of saidports adapted to receive fluid'under high pressure and the other port adapted to receive fluid under low pressure. an abutment blade in the form of a rectangular plate between said ports engageable at its inner end with said rotor and extending radially outwardly relative to said rotor and in the plane of the rotor axis, said housing having a rectangular guide slot in which said blade has sliding bearing fit, said blade at its inner end having a contact edge adjacent to and parallel with one side thereof and providing the sole contact area for engaging the rotor, said blade end at one side of said edge being sloped or beveled to present an unvarying sloping surface to the pressure of the fluid flow through the high pressure port, means for subjecting the outer end of said blade to the pressure of the high pressure flow, said sloping surface being at a small acute angle with the rotor surface engaged by said edge whereby the high pressure fluid will exert against the blade a wedging action having a minimum lateral component and a maximum longitudinal component tending to shift it outwardly in said slot against the high pressure exerted inwardly against the outer end of the blade, the area of said sloping surface being so proportioned to the area at the outer end of the blade exposed to the high pressure that the pressure against the outer end may counteract to a assist in holding the blade against the rotor but functioning primarily to hold the blade to the rotor until pressure has been built up in the cylinder working chamber.

3,. A hydraulic rotary structure of the type described comprising a housing defining a cylinder space, a rotor within said space of elliptical crosssection for cooperating with the cylinder space to define a working chamber, ports for said working chamber connected with the exterior of said housing, one of said ports adapted to receive fluid under high'pressure and the other port adapted to receive fluid under low pressure, an abutment blade in the form of a rectangular plate between saidv ports engageable at its inner end against said rotor and extending radially outwardly relative to said rotor and in the plane of the rotor axis, said housing having a guide chamber in which said blade has sliding bearing fit, spring means urging said blade into contact with said rotor, means for subjecting the outer end of the blade to the pressure of the high pressure flow,

said blade at its inner end having a contact edge close to the side of the blade facing the low pressure -flow port and being beveled off in opposite directions from said edge to leave a comparatively small beveled surface exposed to the low pressure flow and a comparatively large bevel surfaceexposed to the high pressure flow, and said beveled surfaces being at a small acute angle with the rotor surface, said edge forming the sole area'of contact ofv the blade with the rotor and being so disposed between the sides of the blade. that the high pressure flow component radially. outwardly against said large bevel surface on the

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