US3782867A

US3782867A - Fluid power converter

Info

Publication number: US3782867A
Application number: US00240387A
Authority: US
Inventors: C Gerlach; E Schroeder
Original assignee: Rineer Hydraulics Inc
Current assignee: AMERICAN NATIONAL BANK
Priority date: 1972-04-03
Filing date: 1972-04-03
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01

Abstract

A fluid power converter, such as a hydraulic fluid pump or motor, having a rotor and stator each having sealing vanes and in which the stator includes a contoured periphery consisting of harmonic curves which reduces rotor vane acceleration and provides a constant output source independent of rotational angle. The rotor periphery consisting of contoured curves shaped to impart harmonic motion to the stator vanes for reducing stator vane accelerations. The rotor and stator vanes having different thicknesses and provided with hydraulic and spring loading with the thicker vanes having a higer loading force thereby preventing destructive detenting of the vanes with respect to each other. Fluid timing plates for the rotor vanes sealing the hydraulic loading fluid in the rotor vane pockets during vane interaction periods for reducing wear and noise of the vane.

Description

United States Patent m1 Gerlach et al.

1 Jan. 1,1974

[ FLUID POWER CONVERTER [75] Inventors: Charles R. Gerlach; Edgar C.

Schroeder, both of San Antonio,

[2]] App]. No.: 240,387

FOREIGN PATENTS OR APPLICATIONS Great Britain 418/221 1 Primary ExaminerCar1ton R. Croyle Assistant Examiner-John J. Vrablik Attorney-James F. Weller et a1.

[57] ABSTRACT A fluid power converter, such as a hydraulic fluid pump or motor, having a rotor and stator each having sealing vanes and in which the stator includes a contoured periphery consisting of harmonic curves which reduces rotor vane acceleration and provides a constant output source independent of rotational angle. The rotor periphery consisting of contoured curves shaped to impart harmonic motion to the stator vanes for reducing stator vane accelerations. The rotor and stator vanes having different thicknesses and provided with. heydrau is p, Qa n v i.th. he hic vanes having a higher loading force thereby preventing destructive detenting of the vanes with respect to each other. Fluid timing plates for the rotor vanes sealing the hydraulic loading fluid in the rotor vane pockets during vane interaction periods for reducing wear and noise of the vane.

8 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION A hydraulic motor and pump having vane elements on both the rotor and stator in which the contours of the stator and rotor are designed to provide a constant net torque is shown in copending patent application Ser. No. 883,692, entitled Fluid Power Converter", filed Dec. 10, 1969 now US. Pat. No. 3,622,797.

In the prior patent, the periphery contour causes excessive vane acceleration forces for high speed operation because of the steep ramps between the recesses and the vanes. The present invention is directed to an improved fluid power converter in which the peripheries of the stator and/or the rotor, are contoured to not only provide a zero torque fluctuation or constant net torque, but overcome the problem of excessive vane acceleration forces during high speed operation. In addition, the present invention is directed to an improved fluid power converter in which various improvements are made in the vanes and vane loading to avoid the destructive detenting of the stator and rotor vanes with respect to each other.

SUMMARY One feature of the present invention is the provision of a fluid power converter having a rotor and a stator which are concentrically mounted and rotatable one to the other end each of which have a periphery including a plurality of equally spaced radially extending slots for receiving a vane therein in which the stator contour includes a plurality of recesses defined by a harmonic curve having its center coaxial with the common center and having an angular periphery extent substantially equal to 360 divided by the number of the stator vanes whereby the stator contour will provide a constant torque design and yet avoid excessive rotor vane acceleration forces which occur at high speed operations in stator designs having periphery contours with steep ramps.

Another feature of the present invention is a fluid power converter in which the rotor member has a contoured periphery having a plurality of recesses defined by a curve which is substantially harmonic for imparting harmonic motion to the stator vanes and thereby eliminating excessive stator vane acceleration forces having its center coaxial with the common center and having an angular periphery extent substantially equal to 360 divided by the number of rotor vanes.

Another feature of the present fluid power converter is to reduce the detenting action between the rotor and stator vanes by making the vanes in the stator of a different thickness than the vanes in the rotor whereby the thicker vanes will not fit in the thinner slots and by loading the thicker vanes with a greater vane loading than the thinner vane so that the thinner vanes cannot detent into the thicker vane slots because they do not have a sufficient force.

Yet a still further feature of the present invention is the provision of a fluid converter in which both the rotor and stator vanes are hydraulically loaded with a high pressure fluid at all times but in which the fluid in place under the rotor vane is trapped or locked during the period the rotor and stator vanes cross each other thereby limiting the extent to which the rotor vanes can be displaced down in their slots thereby reducing the tendency of the stator vanes to contact the sharp corners of the rotor slot, prevent violent acceleration of the rotor vanes down into their slots because of high speed interaction with the stator vanes which causes excessive noise and loading of the rotor vane springs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic elevational view, in cross section, showing the preferred embodiment of a rotor and stator of a fluid power converter according to the present invention, and

FIG. 2 is a schematic elevational view, in cross section, showing half of one of the timing plates of the present invention and illustrating a rotor with a modified contour.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and particularly to FIG. 1, the reference numeral 10 generally indicates a fluid power converter, either gas or hydraulic, of the present invention. While either member of the converter 10 may be designed to be the stator and the other the rotor, for purposes of illustration, member 12 may be the stator and member 14 may be the rotor.

In order to obtain a theoretical constant torque design, it is necessary to provide an even number of both rotor and stator vanes and there being more rotor vanes than stator vanes by at least two. The stator 12 is shown as including a plurality of radially extending valves receiving slots 22 for purposes of illustration only, here shown as four in number equallv spaced around the stator 12 and each of which receives any suitable type of valve element, here shown as self-pressurizing loading vanes 24 therein whose outer ends 25 contact the outer periphery 18 of the rotor 14. The inner periphery 16 of the stator 12 and the outer periphery 18 of the rotor 14 are suitably contoured, as will be more fully described hereinafter in detail, to provide an annular fluid space 20 therebetween.

Similarly, the rotor 14 includes a plurality of equally spaced valve element receiving slots 30, here shown as six for purposes of illustration only, each of which receives a valve element such as a vane 32 wherein the outer end 33 of which engages the inner periphery 16 of the stator 12. i

Fluid passageways

26 and 28 are provided on either side of the valve elements 24 in the stator 12 one of which, such as passageway 26 may be a fluid inlet and the other passageway, such as passageway 28, may be a fluid outlet. Thus, assuming that the fluid power converter 12 is acting as a motor with the fluid coming in the fluid inlet passageways 26 and out of the fluid outlet passageways 28, the rotor 14 will rotate counterclockwise relative to the stator 12.

In determining the proper contours of the periphery 16 and the stator 12 and of the periphery 18 of the rotor 14, it is to be noted that a constant torque output may be obtained so long as at least one of the peripheries 16 and 18 includes properly sized and shaped fluid recesses. However, in order to obtain maximum fluid displacement and thus maximum output for a given size, it is desirable that both peripheries 16 and 18 include working recesses.

In the particular illustration shown in FIG. 1, utilizing six vanes 32 on the rotor 14 and four vanes 24 on' the rotor 12, the stator contains four contoured recesses 40.

tendible stator vanes 24 which seal against the rotor periphery 18. The rotor contains six contoured recesses 50 of nominally 60 angular extent, separated by six extendible rotor vanes 32 which seal against the stator periphery 16. The stator and rotor periphery contours are designed to always provide a theoretically perfect or constant output torque, independent of rotational angles.

Of course, the rotor and stator contour as described in US. Pat. No. 3,622,797, also provided a theoretical constant output torque, but in that design the vanes were required to move across relatively steep ramps and cause excessive vane acceleration forces at high speed operation which is undesirable. In one embodiment of the present apparatus 10, each of the stator recesses 40 is of a harmonic design. Thus, each of the recesses 40 is defined by a harmonic curve 42 having its center coaxial with said common center and having an angular periphery extent substantially equal to 360 divided by the number of the stator vanes. The displacement of the harmonic curves 42 from the pitch diameter for the maximum diameter of rotor 14 equals (Ax)/2 (l cos 4 6), where Ax is the maximum displacement and is 360. the stator 12 by having the harmonic curves 42, discounting the rotor vane widths, is a constant torque design by virtue of providing an equal sum total displacement for all working rotor vanes 32 as they move around the periphery 16 of the stator 12.

Similarly, the rotor recesses 50 are each defined by a curve 52 which is nominally a harmonic curve having its center coaxial with said common center and having an angular periphery extent substantially equal to 360 divided by the number of rotor vanes. In practice, the rotor contour 52 may be slightly modified to account for the effect ofa finite vane width so that the resultant contour imparts a harmonic motion to the stator vanes. Theoretical harmonic curves 52 on the rotor 14, discounting the finite width of the stator vanes 24, would provide a constant sum total displacement for the four stator vanes 24 and the stator vanes 24 working or sealing against the harmonic contoured rotor-14 provide a constant output torque. Taking into account the finite stator vane width the sum total displacement of the stator vanes is not precisely constant there being a small error because the vanes do not experience harmonic motion, even though the rotor surface is ofa harmonic design. Therefore, this slight error may be corrected by modifying the rotor contour 52 to impart harmonic motion to the stator vanes, but the contour 52 will still be substantially harmonic. The design of the harmonic contoured stator 12 and the substantially harmonic contoured rotor 14, while sacrificing some amount of displacement, provides a superior high speed performance.

As previously mentioned, in order to obtain maximum fluid displacement and thus maximum output for a given size apparatus 10, it is desirable that both peripheries l6 and 18 include working recesses. However, if desired, the working recesses may be omitted from either the stator 12 or the rotor 14. As best seen in FIG. 2, the recesses 50 have been omitted from the rotor 14 and the periphery 18a thereof is merely a circle of constant radius. Similarly, and not shown, the recesses 40 in the stator 12 may be omitted and the periphery 18 may be circular.

Another problem in general encountered in fluid power converters having vanes in both the rotor and stator is the interaction between the vanes on the rotor with the vanes on the stator. That is, as the rotor and stator rotate relative to each other the vanes on the rotor will cross the vanes on the stator and cause excessive noise and destructive detenting of the vanes one with respect to the other. Another feature of the present invention is the improved design of the stator and the rotor vanes and loading means for the vanes. While a fluid converter 10 can be initially manufactured wherein the rotor vanes 32 and the stator vanes 24 are precisely as tall as their

respective slots

30 and 22, and thus initially prevent the rotor vanes 24 from catching in the stator slots 22 and preventing the stator vanes 24 from catching in the rotor slots 30. However, subsequent wear may permit the vanes 32 on the rotor 18 to extend into the stator slots 22 or the stator vanes 24 to extend over into rotor slots 30 causing undesirable noise and damage. To prevent this occurrence, the vanes on either the stator 12 or the rotor 14 are made thicker than the vanes on the other member. For example, and referring to FIG. 1, the stator vanes 24 are thicker, preferably about 30 percent, than the rotor vanes 32. Thus, the stator vanes 24 cannot detent into rotor slots 30 because the vanes 24 are too wide. In addition, the loading on the back of the stator vanes 24 may be made higher than the loading on the back of the rotor vanes 32 so that the smaller rotor vanes 32 cannot detent into a larger slot 22 because the loading force on the rotor vanes 32 will be less than the loading force on the stator vanes 24. The loading on the back of the stator vanes 24 may be conventionally accomplished by providing high pressure hydraulic fluid in the slots 22 acting against the back of the stator vanes 24 from the high pressure supply ports 26 or a separate supply and- /or springs 54. Obviously, if the hydraulic fluid used for loading the stator vanes 24 and the rotor vanes 32 is from the same supply the loading force on the stator vanes 22 will be greater than the loading force on the rotor vanes 32 because of the greater thickness of the stator vanes 24. Of course, if the loading on the

vanes

24 and 32 is accomplished solely by

springs

54 and 64, respectively, the stator vane spring 54 are provided with a higher resilient force than the rotor vane springs 64 in order to insure that the rotor vanes 34 do not detent into a stator slots 22. Preferably, the loading is accomplished by both hydraulic loading and spring loading. An additional benefit of the foregoing structure is that the manufacturing tolerances on the vane heights and slot depths may be increased since neither the stator vanes 24 or the rotor vanes 32 need be the full depth of the

slots

22 and 30, respectively.

Ideally, both the rotor vanes 32 and the stator vanes 24 are hydraulically loaded with high pressure of supply fluid at all times, or for all rotational angles. In practice under such conditions, however, it has been found that the stator vanes 24 because of their greater loading slap down the lighter loaded stator vanes 32 causing noise and excessive loading of the rotor vane springs 64 and at low speeds permits the stator vanes 24 to scrape across the sharp edges of the rotor slots 30. That is, the higher loaded stator vanes 24 will overcome the lower loaded rotor vanes 32 and push the rotor vanes 32 inwardly overcoming the hydraulic and spring loading of the rotor vanes 32.

Therefore, another feature of the present invention is the provision of means for locking or trapping the hydraulic loading fluid in place behind the rotor vanes 32 to create a hydraulic lock in the rotor slots 30 when the stator vanes 24 and the rotor vanes 34 interact so that the rotor vanes 32 cannot be pushed down by the stator vanes 24. Suitable means to trap or lock the fluid in place under the rotor vanes are provided such as a timing plate 70, preferably, on each end of the rotor 14. The timing plate 70 includes a plurality of openings 72 which supply high pressure oil through the end plate 70 to a fluid pocket 74 behind each rotor vane 32. The openings 72 are positioned and the pocket 74 are sized so that high pressure oil is supplied to the rotor vanes 32 while they are operating on the stator contours between points A and B. High pressure oil is supplied to the opposing or back side of each timing plate 70 using an appropriate annulus supplied by a check valve system (not shown) which permits high pressure, but not low pressure to enter. Such a check valve system is required only for reversible motors and pumps.

However, it is noted that the timing plates 70 are stationary and that the openings 72 are positioned so that when a moving rotor vane 32 approaches a stator vane 24 the fluid pocket 74 rotates out of communication with the openings 72 thereby sealing the fluid in the pockets 74 so that loading fluid can neither enter nor leave the pockets 74 as the rotor vane 32 travels from point B to point C. Thus, during the period when the rotor and stator vanes must interact or pass over each other, the hydraulic loading fluid beneath the rotor vanes 32 is creating a hydraulic block so that the rotor vanes 32 cannot be violently pushed down by the stator vanes 24.

lt is also noted that because of normal wear on the rotor and stator vane tips, they become slightly curved on the ends. Hence, it is difficult to avoid a slight tendency for the more heavily loaded stator vanes 24 to protrude slightly into the rotor slots 30 during the interaction period unless opposed in some manner. The above described rotor fluid trapping structure provides a means which also avoids this problem.

Thus, the present invention provides a periphery contour to a stator and/or a rotor of a harmonic curve which achieves an idea] or theoretical constant torque operation for all rotational angles of the rotor. In addition, the rotor periphery may be modified slightly to impart a harmonic motion to the stator vanes for reducing vane acceleration for improved high speed operation. The destructive detenting of the vanes of the rotor relative to the vanes of the stator are reduced by providing the rotor and stator vanes With a differing thickness whereby the thicker vanes cannot enter the narrower slot of the other member and by providing greater loading on the thicker vanes to prevent the thinner vanes from moving into the wider slots of the thicker vanes. The timing plates for the rotor vanes loading seal the hydraulic loading fluid in the rotor vane pockets during the vane interaction period which prevents caming or slapping action of the stator vanes against the rotor vanes to cause the motor vanes to be bounced down into their slots.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as others inherent therein. While presently preferred embodiments of the invention are given for the purpose of disclosure, numerous changes in the details of construction and arrangement of parts will readily suggest themselves to those skilled in the art and which are encompassed within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. in a fluid power converter having a rotor and a stator member, the members being concentrically mounted and rotatable one with respect to the other about a common center, said members having opposing peripheries contoured to provide an annular space therebetween, each of said peripheries including a plurality of equispaced radially extending slots receiving a vane therein, there being an even number of both rotor and stator vanes and there being more rotor vanes than stator vanes, a fluid inlet in the stator adjacent one side of each slot therein and opening into the annular space, a fluid outlet in the stator adjacent the second side of each slot therin and opening into the annular space, the improvement comprising,

the stator periphery including a plurality of recesses each of which is defined by a harmonic curve having its center coaxial with said common center and having an angular periphery extent substantially equal to 360 divided by the number of stator vanes, and

the rotor periphery includes a plurality of recesses each of which is defined by a curve which is substantially harmonic for imparting harmonic motion to the stator vanes and having its center coaxial with said common center and having an angular periphery extent substantially equal to 360 divided by the number of rotor vanes thereby reducing vane acceleration and providing a constant torque converter.

2. The apparatus of claim 1 including,

means for supplying hydraulic fluid on the back of said rotor and stator vanes, and

means for locking the hydraulic fluid on the vanes in one of the rotor and stator in place during the time the rotor and stator vanes cross each other for preventing escape of fluid from the back of the locked vanes.

3. The apparatus of claim 1 including,

the vanes in the stator being of a different thickness than the vanes in the rotor,

means for urging the stator and the rotor vanes out wardly from the stator and rotor, respectively, and

said means urging the vanes outwardly providing a greater force on the greater thickness vanes.

4. The apparatus of claim 6 wherein the means urging the stator and rotor vanes outwardly being springs, and

the springs urging the greater thickness vanes outwardly having a higher force than the springs urging the lesser thickness vanes outwardly.

5. In a hydraulic power converter having a rotor and a stator member, the members being concentrically mounted and rotatable one with respect to the other about a common center, said members having opposing peripheries contoured to provide an annular space therebetween, each of said peripheries including a plurality of equispaced radially extending slots receiving a vane therein, a fluid inlet in the stator adjacent one side of each slot therein and opening into the annular space, a fluid outlet in the stator adjacent thesecond side of each slot therein and opening into the annular space, the improvement comprising,

hydraulic fluid applied against the back of the stator vanes and the rotor vanes for urging the stator vanes and the rotor vanes outwardly from the stator and rotor, respectively, and

locking means for preventing escape of fluid from the back of the vanes thereby sealing the hydraulic fluid acting on the vanes in one of the rotor and stator in place during the time the rotor and stator vanes cross each other thereby preventing the locked vanes from being pushed into their slots by the other vanes.

6. The apparatus of claim wherein,

means for urging the stator and the rotor vanes outwardly from the stator and rotor, respectively,

said means urging the vanes outwardly providing a greater force on the greater thickness vanes, and

said means for urging the stator and rotor vanes outwardly includes,

hydraulic fluid applied against the back of the vanes, and

also includes springs applied against the back of the vanes, the springs urging the greater thickness vanes outwardly having a greater force than the springs urging the lesser thickness vanes outwardly.

7. The apparatus of claim 5 wherein the vanes in the stator being of a different thickness than the vanes in the rotor, and wherein the locking means act on the thinner vanes.

8. The apparatus of claim 7 wherein the thinner vanes are the rotor vanes and wherein the hydraulic locking means includes a plate on both ends of the rotor having timing ports, said ports positioned between the back of the rotor vanes and high pressure hydraulic fluid, and said ports normally open but being closed during the time when the rotor and stator vanes cross each other.

Claims

1. In a fluid power converter having a rotor and a stator member, the members being concentrically mounted and rotatable one with respect to the other about a common center, said members having opposing peripheries contoured to provide an annular space therebetween, each of said peripheries including a plurality of equispaced radially extending slots receiving a vane therein, there being an even number of both rotor and stator vanes and there being more rotor vanes than stator vanes, a fluid inlet in the stator adjacent one side of each slot therein and opening into the annular space, a fluid outlet in the stator adjacent the second side of each slot therin and opening into the annular space, the improvement comprising, the stator periphery including a plurality of recesses each of which is defined by a harmonic curve having its center coaxial with said common center and having an angular periphEry extent substantially equal to 360* divided by the number of stator vanes, and the rotor periphery includes a plurality of recesses each of which is defined by a curve which is substantially harmonic for imparting harmonic motion to the stator vanes and having its center coaxial with said common center and having an angular periphery extent substantially equal to 360* divided by the number of rotor vanes thereby reducing vane acceleration and providing a constant torque converter.

2. The apparatus of claim 1 including, means for supplying hydraulic fluid on the back of said rotor and stator vanes, and means for locking the hydraulic fluid on the vanes in one of the rotor and stator in place during the time the rotor and stator vanes cross each other for preventing escape of fluid from the back of the locked vanes.

3. The apparatus of claim 1 including, the vanes in the stator being of a different thickness than the vanes in the rotor, means for urging the stator and the rotor vanes outwardly from the stator and rotor, respectively, and said means urging the vanes outwardly providing a greater force on the greater thickness vanes.

4. The apparatus of claim 6 wherein the means urging the stator and rotor vanes outwardly being springs, and the springs urging the greater thickness vanes outwardly having a higher force than the springs urging the lesser thickness vanes outwardly.

5. In a hydraulic power converter having a rotor and a stator member, the members being concentrically mounted and rotatable one with respect to the other about a common center, said members having opposing peripheries contoured to provide an annular space therebetween, each of said peripheries including a plurality of equispaced radially extending slots receiving a vane therein, a fluid inlet in the stator adjacent one side of each slot therein and opening into the annular space, a fluid outlet in the stator adjacent the second side of each slot therein and opening into the annular space, the improvement comprising, hydraulic fluid applied against the back of the stator vanes and the rotor vanes for urging the stator vanes and the rotor vanes outwardly from the stator and rotor, respectively, and locking means for preventing escape of fluid from the back of the vanes thereby sealing the hydraulic fluid acting on the vanes in one of the rotor and stator in place during the time the rotor and stator vanes cross each other thereby preventing the locked vanes from being pushed into their slots by the other vanes.

6. The apparatus of claim 5 wherein, the vanes in the stator being of a different thickness than the vanes in the rotor, means for urging the stator and the rotor vanes outwardly from the stator and rotor, respectively, said means urging the vanes outwardly providing a greater force on the greater thickness vanes, and said means for urging the stator and rotor vanes outwardly includes, hydraulic fluid applied against the back of the vanes, and also includes springs applied against the back of the vanes, the springs urging the greater thickness vanes outwardly having a greater force than the springs urging the lesser thickness vanes outwardly.