US3016017A - Rotary pumps and motors - Google Patents

Description

Jan. 9, 1962 c. s. PRENDERGAST 3,0 7

ROTARY PUMPS AND MOTORS Filed Aug. 21, 1959 4 Sheets-Sheet 1 F/6.2."-/ 5 loc K F H Pain 12 22;

Jan. 9, 1962 C. S. PRENDERGAST ROTARY PUMPS AND MOTORS Filed Aug. 21, 1959 F/GEB.

4 Sheets-Sheet 2 Jan. 9, 1962 c. s. PRENDERGAST 3,01

ROTARY PUMPS AND MOTORS 4 Sheets-Sheet 3 Filed Aug. 21, 1959 FIGS.

corr v PR5 ERGAST,

B 5 5 L Attorney //v VE/VTOR CHARLL'S Jan. 9, 1962 c. s. PRENDERGAST 3,016,017

ROTARY PUMPS AND MOTORS Filed Aug. 21, 1959 4 Sheets-Sheet 4 3,3 F/ G 8. 7 28b 33a WIN/[A1709 C/MRL saorr 8o P/mvomawr,

Atlorne United States Patent Oflice 3,015,017 Patented Jan. 9, 1962 3,016,017 ROTARY PUMPS AND MOTORS Charles Scott Prendergast, Shoreham-by-Sea, England, assignor to Brakeshoe International, S.A., Geneva, Switzerland, a corporation of Switzerland Filed Aug. 21, 1959, Ser. No. 835,301 Claims priority, application Great Britain Dec. 23, 1958 Claims. (Cl. 1034) This invention relates to pumps and motors of the kind having three rotors concentrically mounted and rotatable with a central shaft, a similar number of bored stators surrounding said rotors at least the centre one of which stators is or may be set eccentrically in relation to the axis of the shaft, and vanes slidable in radial grooves in each rotor having an eccentric stator.

An object of the invention is to eliminate the previous necessity in machines of this kind for separating or partitioning plates or like members between the respective fluid chambers.

According to the invention and to the attainment of this object I provide a pump or motor of the aforesaid kind in which the diameter of the centre rotor differs from that of the two end rotors and the product of the 7 diameter and axial width of either of the two end rotors is approximately equal to half the product of the diameter and axial width of the centre rotor. This arrangement provides sealing surfaces between the respective fluid chambers without the necessity for separating or partitioning plates or equivalent members.

The invention is applicable to a pump or motor in which the bores of the stators for all three rotors are eccentric to the shaft axis and in which all three rotors are equipped with vanes slidable in radial grooves there- However, the invention is also applicable to a pump or motor in which the bore of the centre stator alone is eccentric to the shaft axis and its rotor is equipped with vanes slidable in radial grooves therein, while the bore of each of the end stators is concentric to the shaft axis and carries two abutments (which may be radially slidable) on approximately the same centre line as the eccentricity of the centre stator, these abutments making sealing contact with the unbroken periphery of the pertaining rotor.

In either case the pump or motor may be so constructed that the eccentricity of the bore of the centre stator is capable of being varied at will as in accordance with my patent application Ser. No. 710,573, now PatentNo. 2,972,953.

In order that the invention may be better understood two embodiments thereof as applied to'pumps are illustrated by way of example on the accompanying drawings to which reference is now made.

FIG. 1 is a longitudinal section on II of FIG. 2.

FIG. 2 is a transverse section on II-II of FIG. 1.

FIG. 3 is a transverse section on IIIIII of FIG.

FIG. 4 is a transverse section on IV-IV of FIG.

FIG. 5 is a longitudinal section on V-V of HG.

FIG. 6 is a transverse section on VI-VI of FIG. FIG. 7 is a transverse section on VII-VII of'FiG,

FIG. 8 is a transverse section on VIII-VIII of FIG.

Referring" first to FIGURES 1 to 4, a shaft 1 is carried in ball- bearings 2 and 3 mounted in end housings 4 and 5. Keyed to the shaft but free to slide axially on it is"a rotor 6, and rigidly and concentrically mounted on exby that rotors axial width is equal to half the product of the diameter and the axial width of the rotor 6.

Each of the three rotors 6, 7, 8 is provided with eight pairs of equidistant grooves 6a, 7a, 8a respectively, these grooves being of equal depth and extending inwardly from the rotor periphery and their bottoms being connected by ducts 6b, 7b, 8b respectively to said periphery between adjacent pairs of grooves. The construction of each rotor is in accordance with my Patent No. 2,928,350.

Surrounding the rotor 6 is an adjustable stator 9, approximately the same axial width as this rotor and having a circular bore which is substantially greater in diameter than the rotor but substantially less than a circle inscribed at the bottoms of the grooves 7a and 8a; surrounding the rotors 7 and 8 are stators 12 and 13 of approximately the same axial width as these rotors and having circular bores which are substantially greater in diameter than the rotors. The described arrangement of the rotors and their stators forms sealing surfaces between the respective fluid chambers without the necessity for separating or partitioning plates thereby simplifying the construction.

The adjustable stator 9 is carried in slides 10a and 10b in an outer member 10 and has freedom to move transversely in these slides in relation to the rotor 6 from a position where the centre of the stator bore is a predetermined distance on one side of the shaft axis to a position in which it is a predetermined distance on the other side of the shaft axis. Sixteen vanes 11, approximately the same axial width as the rotor 6, are free to slide radially in the grooves 6a; they maintain contact with the bore of the stator 9 by centrifugal force when the rotor is rotated (with or without the aid of springs). Chambers 9a and 9b extend radially outwards from the bore of the stator 9 and are separated by equal unbroken portions 90 of the stator bore, each of these portions havin a reater angular length'than the an ular distance a g a Chamber 9b is a non-pressure chamber and is connected tensions at opposite endsof the rotor 6 are two other '6. In fact'the dia'meterof the rotor,7 'or 8 multiplied by a duct 9e to a non-pressure port 10d connected to the fluid reservoir. f

The stators 12 and 13 are fixed radially in relation to the rotors 7 and 8, their bores having a predetermined and identical eccentricity in relation to the shaft axis on the same transverse plane as that on which the adjustable stator 9 moves. Sixteen vanes 14 and sixteen vanes 15, approximately the same axial width as the rotors 7 and 8, are free to slide radially in the grooves 7a and 8a respectively; these vanes maintain contact with the bores of the stators 12 and 13 by centrifugal force when the rotors are rotated (with or without the aid of springs). Chambers 12a, 12b and 13a, 13b extend radially outwards from the bores of the stators 12 and 13 respectively, the chambers in each stator being separated by equal unbroken portions of the stator bore or 130, each of these portions having a greater angular length than the angular distance between adjacent pairs of the vanes. The chambers 12a, 12b, and 13a, 13b, 'are on transverse planes at right angles to the plane in which the adjustable stator 9 moves; The chambers 12a and 13a are pressure to the shaft-axis: Duct 17 connects'to the inletpor't 10a in. the outer member 16.

Duct 16 connects to the output port When the described pump is adjusted for full flow, the eccentricity of the adjustable stator 9 is at its maximum and is at 180 to the eccentricities of the stators 12 and 13. There is then a gap between the adjustable stator and the outer member 10. Small diameter holes 9 and 9g connect this gap to the pressure chamber 9a and the non-pressure chamber 9b, thus creating a fluid pressure at this side of the adjustable stator 9 which holds it in the full flow position. When the adjustable stator is in the full flow position and the rotors are rotated, the displacement thus created causes fluid to enter through the ports d and 10a and to be expelled through the utlet port 100.

For the purpose of adjusting the stator 9 at will the outer member 10 is equipped with an adjusting screw 18 and an adjusting nut 19, which are retained in position by a retaining plate 20. By rotating the adjusting nut, the adjusting screw can be moved inwards against the adjustable stator 9 forcing it to move towards the other side of the outer member 10. 7

When the adjustable stator 9 is moved towards the concentric position the displacement created between it and the rotor 6 is reduced and becomes zero when the stator reaches the concentric position, so that at this point the total displacement of the pump is created between the end rotors 7 and 8 and the end stators 12 and j 13. If the adjustable stator 9 is moved farther to become eccentric with the shaft axis in the same direction as the eccentricities of the stators 12 and 13, the displacement created between it and the rotor 6 absorbs a proportion of the fluid displaced by the rotors 7 and 8 and this fluid is expelled through the non-pressure port 10d back to the reservoir. Under these conditions the rotor 6 is being driven by pressure fluid displaced by the rotors 7 and 8 and ,the energy represented by this displacement is being returned to the shaft 1. By moving the adjustable stator 9 far enough in this direction all the fluid displacement by the rotors 7 and 8 is returned to the reservoir through the nonpressure port 10d and apart from volumetric and other losses no energy is absorbed v by the pump.

Referring now to FIGS. 5 to 8, a shaft 21 is carried in ball- bearings 22 and 23 mounted in end housings 24 and 25. Keyed to the shaft but free to slide axially on it is a vane-bearing rotor 26 and rigidly and concentrically mounted on extensions at opposite ends of the rotor 26 are two pressure re-action rotors 27 and 28, all three rotors forming one rotatable unit concentric with the axis a grooves are connected by ducts 26b to said periphery between adjacent pairs of grooves. The construction of the rotor 26 is in accordance with my Patent No. 2,928,350. l

Surrounding the. rotor 26 an adjustable stator 29, approximately the same axial width as the rotor'and having a circularbore which is substantially greaterin" diameter than the rotor but substantially less thanfthe di-' ameter of either of the pressure re-action rotors27, 28;

surrounding the" pressure re-action rotors '27, 28 are r fixedstators 32, 33 .r'espectively, approximately the same :axi'a'l width as the rotors and having circular bores which 1 are concentric with and'slightly greater in diameter than the rotors 27, 28. This arrangement Be he rotorsla nd' their stators forms sealing surfaces between the respective fluid. chambers withoutthe necessity for separating or partitioning "plates. :I V

. nectthis gap to the outletchamb'e'r 29a and the inlet by centrifugal force when the rotor is rotated (with or Without the aid of springs). Chambers 29aand 29b extend radially outwards from the bore of the stator 29 and are separated by equal unbroken portions 29c of the stator bore, each of these unbroken portions having a greater angular length than the angular distance between adjacent pairs of vanes 31-. The chambers 29a and 29b are situated on a transverse plane at right angles to that on which the adjustable stator 29 moves. Chamber 29a is the outlet chamber and is connected directly to the pump outlet port 300 in the outer member 30. Chamber 29b is the inlet chamber and is connected directly to the inlet port 30d. 7

Each of the fixed stators 32 and 33 has two radial grooves 32a and 33a respectively, which extend radially outwards from the bores of the stators. Two abutments 34 and two abutments 35 are free to slide radially in the grooves 32a and 33a respectively, and these abutments are constrained to make sealing contact with the pressure reaction rotors 27 and 28 by hydraulic pressure (with or without the aid of springs). Abutments 34 and 35 are situated on a centre line parallel to the slides 30a and 30b in which the adjustable stator 29 moves. The annular spaces between the pressure reaction rotors 27 and 28 and the fixed stators 32 and 33 are divided into four chambers 27a, 27b and 28a, 28b by the abutments 34 and 35. Chambers 27a and 28a are connected by ducting (not shown) to the outlet chamber 29a and are situated at 180 to it. Chambers 27b and 28b are connected by ducting (not shown) to the inlet chamber 2% and are situated at 180 to it.

Owing to the stated dimensional relationship between the pressurereaction rotors 27 and 28 and the vane-bearing rotor 26, the sum of the cross-sectional areasof the rotors 27 and 28 is equal to the cross-sectional area of the rotor 26. As the chambers 27a, and 28a'are at 180 tothe outlet chamber 29a and are hydraulically connected to it, any hydraulic pressure developed in the output chamber 29a is balanced by the hydraulic pressures in the chambers 27a and 28a thus tending to eliminate bearing loading due to internal hydraulic pressure.

When the rotor 26 is rotated fluid. is displaced between it and the adjustable stator 29 and by reason of this displacement fluid'enters through the inlet port 30d and is expelled through the outlet port 300. The volume of fluid displaced can be varied from zero to maximum by adjusting the position of the adjustable stator 29 between the position of concentricity with the shaft axis and the position of maximum eccentricity withjthe shaft axis.

When the pump is adjusted for full flow, the eccentricity of the adjustable stator 29 is at its maximum. There is then a gap between the adjustable'st'ator and the outer member. Small diameter holesj29j and 29g conchamber. "2%. thus creating a fluid pressure at. this side of theadjustable stator 29 whichh'olds' it in the full flow position; on the opposite side-tor the outer member 30 are an adjusting screw 38 and ah adjusting nut 39 ingit-to move towardslthe concentric position. '1 a i "It will be understood yifthos jsliilled inj'ith'e art that a although I- have described jlation: to pumps it'isapplicableftofthe constrictionof 7 jhydraulic motors. Furtherl many conseueagnar :det'ails 'fwhich' are retained in position -by afretaining plate 40.

By rotating'the adjusting nut the ,adjusting sCIFW can be moved inwards against the adjustable stator. 29, forcthe invention in detailin remay be modified within the scope of the invention; for instance means other than described may be provided for adjusting the eccentricity of the centre stator.

I claim:

1. A pump or motor comprising end housings; a shaft journalled for rotation in said end housings; three rotors arranged side-by-side with their adjacent surfaces in sealing contact, mounted on and rotatable with said shaft; three bored stators each surrounding one of said rotors to form part annular fluid spaces of equal angular length therewith, at least the bore of the center stator being eccentric to the axis of said shaft; a plurality of vanes equally spaced and slidable in radial grooves formed in at least the center rotor to provide with its stator a series of fluid displacement chambers; fluid inlet and outlet chambers of equal angular length on opposite sides of the plane of eccentricity of at least the center stator bore, lands of equal angular length situated on the circumference of the stator bore separating said inlet and outlet chambers, each land having an angular length at least equal to the angular distance between adjacent rotor vanes; ducting connecting the part annular fluid space on each side of the plane of eccentricity of the center stator to the part annular fluid spaces contained by the end rotors and their stators on the opposite side of said plane; the diameter of the center rotor differing from that of the two end rotors in sealing contact with it, thereby affording sealing surfaces between the respective part annular fluid spaces contained by the three rotors and stators without partitioning members between the rotors, and the product of the diameter and the axial width of each of the end rotors being substantially equal to half the product of the diameter and the axial width of the center rotor thereby insuring that the area under radial hydraulic pressure of the center rotor is approximately equal and opposite to the sum of the areas under hydraulic radial pressure of the two end rotors.

2. A pump or motor as set forth in claim 1, including means for varying at will the eccentricity of the bore of the centre stator.

3. A pump or motor comprising end housings; a shaft journalled for rotation in said end housings; three rotors arranged, side-by-side, with their adjacent surfaces in sealing contact, mounted on said shaft and rotatable with said shaft; three bored stators each surrounding one of said rotors to form part annular fluid spaces of approximately equal angular length therewith, the bores of the stators being eccentric to the axis of said shaft; the eccentricities of the end stators being equal to one another and fixed on coincidental radii on the same plane of eccentricity as the central stator; a plurality of vanes equally spaced and slidable in radial grooves formed in each of said rotors to provide a series of displacement chambers with the bores of their stators; fluid inlet and outlet chambers of equal angular length on opposite sides of the plane of eccentricity of each stator bore, lands situated on the circumference of each stator bore separating said inlet and outlet chambers of each stator, each land having an angular length at least equal to the angular distance between adjacent rotor vanes, ducting connecting the part annular fluid space on each side of the plane of eccentricity of the center stator to the part annular fluid spaces contained by the end rotors and their stators on the opposite side'of said plane; the diameter of the center rotor differing from that of the two end rotors in sealing contact with it, thereby affording sealing surfaces between the respective part annular fluid spaces contained by the three rotors and their stators without partitioning members between the rotors, and the product of the diameter and the axial width of each end rotor being substantially equal to half the product of the diameter and the axial width of the center rotor thereby ensuring that the area under radial hydraulic pressure of the center rotor is approximately equal and opposite to the sum of the areas under hydraulic radial pressure of the two end rotors.

4. A pump or motor as set forth in claim 3, including means for varying at will the eccentricity of the bore of the center stator on the same plane as the fixed eccentricities of the end stators.

5. A pump or motor comprising end housings; a shaft journalled for rotation in said end housings; three rotors arranged side-by-side with their adjacent surfaces in sealing contact, mounted on said shaft and rotatable with said shaft; three bored stators each surrounding one of said rotors to form part annular spaces of equal angular length therewith, the bore of the center stator being eccentric to the axis of said shaft and the bores of the end stators being concentric to said axis; a plurality of vanes equally spaced and slidable in radial grooves in the center rotor to form with its stator a series of displacement chambers; two abutments slidable in radial grooves formed in the concentric bore of each end stator and bearing on the pertaining rotor on approximately the same plane as the plane of eccentricity of the center stator bore with the shaft axis; fluid inlet and outlet chambers of equfl angular length on opposite sides of the plane of eccentricity of the center stator bore, lands of equal angular length situated on the circumference of the stator bore separating said inlet and outlet chambers, the angular length of each land being at least equal to the angular distance between adjacent rotor vanes; ducting connecting the part annular fluid space on each side of the plane of eccentricity of the center stator to the part annular fluid spaces contained by the end rotors and their stators on the opposite side of said plane; the diameter of the center rotor differing from that of the end rotors in sealing contact with it, thereby affording sealing surfaces between the respective part annular fluid spaces contained by the three rotors and stators without partitioning members between the rotors, and the product of the diameter and the axial width of each of the end rotors being substantially equal to half the product of the diameter and the axial width of the center rotor thereby ensuring that the area under radial hydraulic pressure of the center rotor is approximately equal and opposite to the sum of the areas under hydraulic radial pressure of the two end rotors.

6. A pump or motor as set forth in claim 5, including means for varying at will the eccentricity of the bore of the centre stator.

References Cited in the file of this patent UNITED STATES PATENTS 722,560 Buckingham Mar. 10, 1903 1,927,799 Mann Sept. 19, 1933 2,013,397 Balsigcr Sept. 3, 1935 2,358,275 Hess Sept. 12, 1944 2,368,789 Tucker Feb. 6, 1945 2,513,446 Brown July 4, 1950 2,754,762 Prendergast July 17, 1956 2,885,960 Deschamps May 12, 1959 FOREIGN PATENTS 743,088 Great Britain Ian. 11, 1956 819,195 Germany Oct. 31, 1951

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