EP0235273A1 - Positive displacement pump or motor - Google Patents

Abstract

Volumetric hydraulic motor or pump characterized by surface-to-surface contact of all sliding parts with respect to each other (2, 11, 12, 13, 16), capable of high pressures and allowing aerodynamic flow paths and free and therefore also capable of high speeds of rotation.

Description

POSITIVE DISPLACEMENT PUMP OR MOTOR

^~ Technical Field 5 "^{^} This invention relates to a mechanism to convert rotary motion of a shaft into fluid flow or viceversa.

Background Art

10 Hydraulic pumps or motors are classified into two main .categories: The ones using fluid dynamic effects on solid surfaces like centrifugal pumps or Turbines and others that enclose definite volumes of the fluid within rigid elastic or liquid walls like the many types of volumetric pumps, compressors o motors. Referring to the second category, one very common type consists of on

15 cylindical rotor with several vanes inserted into axial slots and this rotor installed inside one casing. By moving the vanes in and out from the rotor an making them contact the casing during the rotation of said rotor, increasing a decreasing volumes are created within the device which can be used for pumping fluids or extracting energy from fluids.

20 The most common type in actual use, has one cylindical rotor, several axial vanes and the rotor in one casing consisting of two or four arcs of cylindrical surfaces of different radius joined by smooth arcuated surfaces. The motion o the vanes relative to the rotor is roughly or perfectly radial.

25 It is a principal object of the present invention to provide one pump or motor where the relative motion of the vanes is roughly or perfectly axial, in the direction of the rotor axis, and the volumes created by the diferent movin parts are in the rotor itself.

30 Summary of the Invention ~~

1

As an underlying principle of my invention an axial vane pump has a cylindrical rotor provided with one shaft at one end and in this rotor, there are a number of plane slots parallel to the rotor axis and one depression all around the center portion of said rotor. Vanes are fi tted into the rotor slots with enough clearance so that they can sl ide axialy in said slots. The rotor is fitted inside one cyl indrical casing wi th enough clearance to be able to rotate . One or several sol id parti tions are physically attached to the casing and total ly occl ude the central depression of the rotor but with enough clearance wi th it, so the rotor can be rotated. The vanes are moved axially relative to the rotor during this rotation, from a position closing the rotor depression to another letting the depression free to avoid physical interference wi th the soli partition attached to the casing.

The axial motion of the vanes is accomplished by the use of any of the known mechanisms that convert rotary motion into l inear motion paral lel to the axis like cams, swash plates, incl ined crankshaft etc . Openings in the casing provide the inlet and outlet ports for the fl uid. The vane pumps or motors have attained a very high hydrostatic performance but their hydrodina ic performances are generally poor, due to the compl icated or restricted flow passageways. In the pump or motor of my invention, the perfection of the flow paths have been brought to the l imit, and in double action pumps or motors this paths are prac¬ tical ly straight and with no restrictions at al l .

Description of the Drawings

Fig. 1 shows an axial section of one pump or motor of single action;

Fig . 2 shows a cross-section of one pump or motor of single action ;

Fig. 3 is an exploded view of the rotor, vanes, sol id partition and vane mechanism of a single action pump or motor;

Fig. 4 is a cross-section of one pump or motor of double action;

Fig. 5 is a axial section of one mul tiple annular vol ume si ngle action pump. Detailed Description

The fol lowing description of speci fic embodiments of the invention il l us¬ trated in the drawings is exemplary of its principles and not intended to l imit the scope of the invention.

Referri ng to figure 3, 11 is a cyl indrical rotor provided wi th one de- pressed zone 4 al l around it. In the figure the depression is cylindrical , therefore, converting the rotor into two parts 11 and 13 of the same diameter joined by another 12, roughly in the middle, of smal ler diameter. A number of slots 14 parallel to the axis are provided in the rotor deep enough so they cut shal low slot in the depressed center part of the rotor. These slots are bl inded at both ends of the rotor. Vanes 16 are fitted into the rotor sl ots in such a way that when total ly inserted, their outer edge is fl ush wi th the outside of th rotor. The axial length of these vanes is larger than the axial length of the rotor depresssion but shorter than the length of the portion 13 of the rotor so that they can be accommodated totally inside it. Push pul l rods 10 of suitable cross-section are joined rigidly or flexibly to the vanes and come out at one en of the rotor through appropriate openings. These push pull rods actuated in one axial direction by any of the known mechani sms that convert rotary into axial ^• motor l ike cams, swash plates, incl ined cranks, etc. Figure 3 shows one male slot cam 8. One sol id parti tion 3 is fi tted in a sl iding relationship into the rotor depressed zone 4. The outside of said partition is fl ush with -the outside of the rotor when ful ly inserted.

One casing 2 wi th straight cyl indrical bore is fi tted in rotating relation ship to the assembly of the rotor 11 provided wi th its corresponding vanes 16 push pull rods 10 parti tion 3 and cam or other rotary to axial mechani sm 8. The casing is provided with two or more openings for fl uid flow in 6, or out 7. The partition 3 is attached to the casing 2 so that it cannot rotate. The mechani sm 8 i s al so attached to the casing 2 in such relationship wi th parti tion 3 that th vanes are retracted inside the portion 13 of the rotor when passing in front of said parti tion 3 and total ly extended across rotor depression 4 in the opposi te side of their rotation. The operation of the single action pump or motor is as follows: The center depression of the rotor 4 forms with the casing an enclosed volume that is interrupted by the partition 3 separating the fluid openings 6.and 7 in the casing 2. The vanes that are extended across this volume in the position just opposite to the partition 3 divide this volume into two, one connected with the opening 6 and another with the out opening 7 in casing 2. When the rotor is rotated the vanes are succesively extended by mechanism 8 so that they always divide the annular volume in two when they are in a position just opposite to partition 3 and clear this partition when they pass in front of it. The con¬ tinuous rotation produces therefore a continuous flow from 6 to 7 inside the pump or motor and a flow from 7 or into 6 when considered from the outside of th device. Figure 4 shows one cross-section of one double action pump or motor wit two partitions 3 and two openings 6 and two 7. It can be clearly seen that the flow from 6 to 7 is practically straight and unrestricted. In this case the vanes move axially in a cycle twice per revolution. The mechanisms 8 is preferably of the type that produces an axial motion o sine or cosine laws with the exception that said mechanism is chosen to be inoperative during a certain arc of the rotation precisely where the vanes are fully extended into the annular volume which is when said vanes produce their power and, therefore are subject to high fluid pressure differences. Once the vanes have passed this zone of. high pressure differences, the pressure is suddenly equalized at both faces of the vane because they are in the outlet^" - opening zone and they can be retracted using only the energy needed to overcome their small friction in the slots and their small inertial forces. The same argument is true for the insertion of the vanes into the annular space because there is no pressure difference when the vanes are in front of the inlet open¬ ing. This pump or motor, unlike preceeding ones has the additional advantage that the contact between relatively sliding surfaces is in every case, with no exception, along a complete surface. That is: the contact is surface to surfac and not line to surface like in previous art. That means that not only the 5 hydrodinamic efficiency but also the hydrostatic will be high. The hydrostatic efficiency is increased by the fact that the zones of higher leakage in vane pumps that is: the tips and ends of the vanes are in this case eliminated at th ends because the rotor slots are blind at both sides and the vanes are pushed against one side of their slot so this leakage path is effectively closed, and a s> 10 the outer tips because the pressure difference between the bottom of the slot and the sliding gap of the vane with the casing pushes the vane outwards, in conjunction with cemrifugal force. The zone where existing vane pumps or motors show maximum wear, that is: the vane tips, is self adjusting in my invention. Although this invention is described with reference to the above specific

15 steps, it will be understood that a variety of modifications may be made withou departing from the principles of the invention. For example, multiple effect pumps or motors or pumps or motors with several depressions 4 in the rotor pro¬ ducing several annular volumes in the same rotor, as shown in Figure 6.

I claim

1. A positive displacement fluid pump or motor comprissing: 30 a) One rotor of cylindrical shape provided with a shaft at one end and with a prurality of axial slots blinded at both ends of said rotor. One annular depression is provided in the outside surface of the rotor.

Claims

b) A prurality of vanes inserted into the rotor slots in sliding relationship with it, so that they fill the slot from surface of rotor to the bottom of the slot and of such axial length so as to be greater than the rotor depression axial width but smaller than at least one of the portions of the rotor at one side of said depression. c) Push pull rods of any suitable cross-section connected to the vanes at one end and extending out of the rotor through properly sealed openings in the corresponding end face of the rotor. d) One or several solid partitions inserted in a sliding relation- ship in the rotor depression, this or these partitions are prevented from rotation by fastening to the pump or motor casing. e) One rotary to axial motion conversion mechanism of known art at one end of the rotor or in any other suitable position fastened to the pump or motor casing and with the proper angular relationship to the partitions 3. f) One casing with one cylindrical bore and provided with outside openings to the location of the rotor depression. This casing fits in rotatable relationship outside the rotor.

2. ^"" The pump or motor of claim 1 wherein the motor depression is in the shape of a straight cylindrical annulus.

3. The pump or motor of claim 1 wherein the rotor slots are not blinded at one end and the vanes themselves come out of the rotor end through said slots. The rotary to axial motion conversion mechanism drives the vanes directly.

4. The pump or motor of claim 1 wherein the rotor has a variety of annular depressions and one single vane per slot, moved from one end of the rotor.

5. The pump or motor of claim 1 wherein the mechanical rotary to axial conversion mechanism is substituted by a rotary hydraulic valve, of known art, supplying pressure or depression to the vane slots through one rotor end with the appropriate timing to effect their sycronized extention or retraction.