GB2023738A - Rotary positive-displacement fluid-machines - Google Patents

Abstract

A pump, or motor, comprises a housing having a fluid inlet and a fluid outlet (30 and 31), and a gerotor set (22) having an internally- toothed member (27) and a co-acting externally-toothed member (28). A shaft, or "wobble stick", (38) has one end connected to a rotary drive shaft (44) and a second end connected to the gerotor member having orbital movement. Commutating passages (37, 37a) and a central opening (35) in the inner gerotor-member (28) cooperate with passages (21a, 33, 34, 40, 41, 42) formed in housing plates (21, 23), the passages in the plate (21) being in communication with the inlet (30) and the outlet (31). Pressure-loaded means to reduce leakage between the plate (23) and the member (28) may be provided, Figs. 12 and 13. <IMAGE>

Description

SPECIFICATION A rotary fluid pressure device An object of this invention is to provide a rotary fluid pressure device including a gerotor having a fixed stator and a rotor which orbits and rotates relative thereto. The rotation of the orbiting rotor provides the output or input at a shaft member. The rotor may have a continuous ring valve on one side and both of the supplies of intake and exhaust pressure fluid on the opposite side. A second embodiment also discloses a fixed stator with an orbiting rotor with the rotating component of the rotor used at the output shaft; but in this embodiment the intake is on the internal diameter of one side of the rotor member with balanced area grooves in communication with the first named intake and exhaust grooves on the opposite side of the rotor so as to provide a hydraulically balanced rotor.

An added object of this invention is to provide a pressure loaded commutator ring urged with a wave spring for initial contact, together with a drive pin connected between the rotor and the commutator ring.

Another object of the invention is to provide a pressure loading plate in the end cover of the housing so as to cause a pressure balance providing a head force towards the manifold and gerotor set.

Other objects and advantages of the present invention will be apparent from the accompanying drawings which illustrate various embodiments by way of example only.

In the drawings: Figure 1 is a central sectional view through a first embodiment of this invention; Figure 2 is a sectional view taken along the line 2-2 of Fig. 1; Figure 3 is a sectional view taken along the line 3-3 of Fig. 1; Figure 4 is a sectional view taken along the line 4-4 of Fig. 1; Figure 5 is a sectional view taken along the line 5-5 of Fig. 1; Figure 5A is a fragmental sectional view taken along the line 5A-5A of Fig. 5; Figure 6 is a sectional view taken along the line 6-6 of Fig. 1; Figure 7 is a sectional view taken along the line 7-7 of Fig. 1; Figure 8 is a central sectional view through a second embodiment of this invention; Figures 9, 10 and 11 are respectively sectional views taken along the lines 9-9, 10-10 and 11-11 of Fig. 8;; Figure 12 is a fragmental sectional view similar to the right-hand end of Fig. 1 and showing a modification including a pressure loaded commutator ring, and Figure 13 is a fragmental sectional view similar to the right-hand end of Fig. 1 and showing a modification including a pressure loading plate in the end cover.

Those familiar with this type of apparatus will understand that while the present invention is being described as a pump using a fluid inlet and a fluid outlet, nevertheless, the same structure may be used as a motor by merely reversing the fluid inlet and outlet so that the high pressure fluid now enters at what was previously the inlet and the device operates as a motor.

In the description and claims occurring hereinafter, the term "housing" is used to include not only the main housing member but also the pressure plate, gerotor set, manifold and end cap, all of these latter parts being connected to the main housing portion by bolts.

Referring now to Fig. 1, the first embodiment of this invention comprises a main housing unit 20 having a radially flat inner end to which is respectively attached a wear plate 21, a gerotor set 22, a manifold 23 and an end cap 24, all of these being secured together by bolts 25, which are shown in the various sectional views but omitted from Fig.

1, but those skilled in this art will recognize that the bolts have heads pressing against the outer right-hand end of the end cap 24 and extending through the members 21, 22 and 23 and threaded tightly into the main housing portion 20. Sealing rings 26 seal all the members against leakage between them.

The gerotor set 22, best seen in Figs. 1 and 4, comprises an internal toothed member 27 which is a stator inside of which a co-acting externally toothed member 28, a rotor, which rotates about its own axis A as seen in Fig. 4, but which is eccentric relative to the centre of the stator 27 by the distance shown between A and B, on the line of eccentricity C, and the rotor orbits about the centre B. During this movement of the rotor and stator a series of cells 29 and 29a form a series of cells of constantly changing size between the rotor and stator, the size of the cells becoming greater on one side of the line of eccentricity, and the cell size becoming smaller on the opposite side. In Fig. 4 the minimum size cell at 29a approaches zero. The rotor rotates in the direction of the arrow D shown in Fig. 4.

The inlet means to the housing is indicated at 30. The fluid outlet means is shown at 31.

The inlet means is connected by means indicated only in dot-dash lines to a continuous annulus 32 in the main housing portion 20.

This annulus opens through the wear plate 21 which has a number of through openings 33, the number of which is not important, but sufficient to take care of the flow of fluid necessary. These openings 33 are connected by connecting passages 33ato an annulus 34 of smaller diameter on the opposite face of the wear plate and opening toward the gerotor 22.

The internal teeth on the stator 27 are provided by cylinders 27a inserted in recesses 276 of over 180 in circumference so as to maintain the cylinders 27a in the positions shown in Fig. 4. It will be understood that the cylinders 27aterminate at the level of the opposite faces of the stator 27. The rotor 28 has external teeth which are formed to fit almost exactly between the internal teeth of the stator, as shown in Fig. 4. The rotor 28 has an open centre 35 surrounded by a sealing strip 36 which is uninterrupted circumferentially and laterally outside of which is an annular liquid intake passageway 37. The axis of rotation for the wobble stick 38 is marked A' in Fig. 1. The axis of rotation for the orbiting movement of the wobble stick 38 relative to the stator is indicated at B in Fig.

4. The line C passing through A and B is herein indicated as the line of eccentricity.

The movement of the rotor herein described is as indicated by the arrow D in Fig. 4. During this rotation the cells 29 on the left-hand side of the line of eccentricity increase in size gradually while the cells 29 on the right-hand side of the line of eccentricity gradually decrease in size as indicated in Fig. 4. Six travel passageways 37a are evenly spaced around the annulus 37 extending parallel to the axis of the rotor. These project radially inwardly from the annulus 37 as seen at 37b, in one embodiment this being about 1/8 of an inch projection (approximately 3.2 mm). Also, it will be noted in Fig. 4, these form part of the intake fluid passageway.

The manifold 23 will be best shown in Figs 5, 5A and 6. Seven parallel through passageways 40 extend through the manifold 23 parallel to its axis. These passages, as best seen in Figs. 5 and 6, have a peculiar crosssection. These passageways 40 will be herein described as "double-trapezoidal". Referring to Fig. 5, it will be seen that one of these openings appears substantially like two trapezoids facing each other with no middle partition and having opposite ends which are not quite parallel but instead are radial. The radially inner side of each opening is composed, not of straight lines, but of lines slightly concave inwardly meeting in a slight peak at the centre 40a. The outer wall of this opening radially, as seen in Fig. 5, may be composed of two straight lines meeting in the centre or preferably a single line slightly convex radially outwardly.The size of each of these openings is such as to fit in the opening, seen in Fig. 4, between two of the cylindrical openings 37a in a circumferential direction and between the central opening and the annulus 37 in a radial direction. Each of the openings 41, of which there are seven evenly spaced, on the side of the manifold toward the gerotor is connected by a passageway 41 a sloping inwardly and downwardly to one of the openings 40 just described.

The manifold 23, as seen in Fig. 6, shows seven inclined passageways 42 in solid lines which co-act with the structure described in connection with the openings 41, passageways 41 a and openings 40 as previously described. These co-acting passageways are shown in broken lines in Fig. 6 to show the co-operation. Seven of such passages 42 are provided extending part-way through the manifold from side to side. These are at a slight angle to the axis of the gerotor and are spaced at a diameter to register, as shown at 33 in broken lines in Fig. 4, substantially fitting against the contour of the stator between two of the cylinders 27a. It will thus be seen that each passageway 42 in the manifold mates with one of the passages 41 a half-way through the manifold so that each of the six passages 40 combines with one of the passages 41 a, 42.

The elongated rigid wobble stick 38 is clearly seen in Fig. 1 and shown in section in Figs. 2 and 3. One end of the wobble stick has a spline connection 44b with the drive shaft 44. It will be noted that this shaft has a solid outer end and a hollow inner end as indicated at 44a The opposite end of the wobble stick has a spline connection 44cwith the centre of the rotor 28. These spline connections are provided in such a manner that the wobble stick may rotate and orbit around the centre axes A, B. The exhaust passageway includes the open centre 35 of the rotor and the open centre 21 a of the wear plate and the hollow 44a, and is completed by four radial passageways 45 and 46 which are connected, as shown in dot-dash lines, with the outlet 31.

Suitable needle bearings are shown at 47 and 48 supporting the drive shaft 44 in the main housing portion 20. Also suitable sealing means as shown at 49 and 50 are provided where the drive shaft passes out of the main housing portion 20.

This embodiment has been described as a pump utilizing the drive shaft 34 for the attachment of power which would cause intake of lower pressure fluid at 30 and exhaust of higher pressure fluid at 31. As previously explained, reversing the connections 30 and 31 will cause the device to operate as a motor producing power on the drive shaft 44.

The operation of the first embodiment as a pump will now be described. Power is supplied to the protruding left end of the drive shaft 44 as seen in Fig. 1. This rotates the shaft, the wobble stick 38, the rotor 28, and also causes the rotor to orbit about the stator 27. This causes the cells 29 to the left of the line of eccentricity C to gradually increase in size causing a suction at the intake 30. The cells 29 on the right-hand side of the line of eccentricity C in Fig. 4 are also caused to progressively decrease in size thus causing the fluid under increased pressure to exhaust at the outlet 31.The incoming fluid, such as air from intake 30, passes through the annular channel 32, the passageways 33ato the annular channel 34, then through the rotor 28 through the annular channels 37 and the cylindrical holes 37a, then through the double trapezoidal openings 40 in the manifold 23, then through the passageways 41 a and 42 in the manifold and through the openings 41 in the manifold and rotor and thus through the cells 29, while other cells 29 are exhausted through the opening 21 a, through the hollow portion 44a of the shaft and through openings 45 and 46 and thus out through the outlet 31.

The second embodiment of this invention is shown in Figs. 8, 9, 10 and 11. Fig. 8 is a central sectional view through the second embodiment with the bearings and seals resembling those seen in Fig. 1 omitted for simplification of the drawings.

The main housing portion 60 has secured to it a wear plate 61, a gerotor set 62, a manifold 63, and an end cap 64, all secured rigidly together by a plurality of bolts 65 extending from the right-hand end of the device as seen in Fig. 8 into threads in the main housing portion 60. The main housing portion has a fluid intake 66 connected by a passage 67 through the housing portion 60 with a continuous annulus chamber 68, which communicates with a plurality of radial openings 69 which lead inwardly to a hollow portion 70a of a drive shaft 70 which is rotatably mounted in the housing portion 60.

An elongated rigid wobble stick 71 has a spline connection 71 a at one end with the drive shaft 70 and another spline connection 71 b at the opposite end with the rotor member of the gerotor set 62. The spline connections 71 a and 71 b are so shaped as to permit the rotation of the wobble stick while at the same time permitting it to follow the orbiting movement of the rotor in the stator as will presently appear.

The wear plate 61 has a circular opening 61 a which permits the necessary movement of the wobble stick 71 and at the same time forms part of the intake passageway for fluid.

The gerotor 62 is best seen in Fig. 9. It comprises a stator 62awhich has a plurality of internally extending teeth formed partly by direct formation in the stator but also in part by six cylindrical members 62bwhich are firmly held in recesses 62cwhich extend for a distance greater than the diameter of each of the cylinders 62bso that they are held firmly in the position shown in Fig. 9. A rotor 72 is shown having a plurality of externally extending teeth 72awhich are shaped to fittingly coact with the internally extending teeth 62, 62a and 62b, these external teeth being one less in number than the internal teeth previously described.The rotor has an axis E which is eccentric relative to the axis F of the stator and the line G passing through points E and F is herein designated as the line of eccentricity.

The rotor is provided with a generally annular ring 73 forming part of the intake passageway for fluid. This passageway is concentric around the axis E. Inside the annular ring 73 is a circular opening 74, also concentric, for the exhaust of fluid from the rotary fluid pressure device.

Referring now to Figs. 9, 10 and 11, Fig.

11 shows the face of the manifold toward the gerotor structure 62. Centrally there is the exhaust opening 75 which communicates with the exhaust opening 74. In the next circle, and concentric, are seven rotor communicating openings 76, and in an outer concentric circle are seven passageway openings 77 so positioned that they co-operate circumferentially with the cells 80 which are formed in changing fashion between the rotor and the stator as seen in Fig. 9.

Fig. 10 shows the face of the manifold 63 toward the end cap 64. This shows the through passageways 76 each connected to one of the openings 77 by means of angular passageways 78 and 79, each pair of which joins at an opening 79a.

The co-operation of these parts is shown in dot-dash lines in Fig. 9 at 81. This shows one of the openings 77 in position to co-operate with a cell 80a at the top of Fig. 9 and it is in co-operation through passageways 78 and 79, here shown diagrammatically, with one of the openings 76, which might be said to be about two and one-half positions away going around the circle. It will now be seen how the radially outward openings 73a in the annular ring 73 co-operate with the communicating passageways 76. There are six of the formations 73a and each comprises a central, radially outermost portion 73bwhich extends substantially circumferentially and at each end of this outermost portion is a radially and circumferentially inwardly sloping portion 73c which extends to a radially innermost separating portion 73d.Each of the passageways 76 is herein described as double trapezoidal in section inasmuch as the opposite halves of the section are approximately trapezoid with their wider edges opening toward each other in the centre. It will now be seen in Fig. 9 that when the dead pocket 80a at the top of Fig. 9 is in communication with its associated opening 77, then the other end of the connection through the 78, 79 connection and shown at 76 in dot-dash lines will illustrate how the exhaust pocket relates to cell 80a is shut off before the fluid is transferred from the associated intake pocket 76. This gives the dead centre pocket a higher pressure than the supply at 66 because the fluid is trapped at that particular moment. This higher pressure causes the rotor 72 to seal better against the cylindrical members 62b on the opposite side of the axis.This higher pressure in cell 80a also provides oil to the pivot roll near the upper dead centres in Fig. 9 whereby the rotor floats on a hydrodynamic oil film thus giving a higher mechanical efficiency output.

It will now be seen that the shape of each of the portions 73aof the annular ring 73 match fairly well with the radially outer edges of the double trapezoidal passageways 76.

It should now be apparent how the operation of this device as shown in Figs. 8 to 11 operates. Power is applied to the shaft 70 causing the rotor 72 to rotate in the stator 62a in the direction of the arrow shown in Fig. 9. The intake flow is from the inlet 66 through passageways 67 and 68, then through the hollow shaft portion 70a and through the central opening 61 a in the wear plate. Then the flow is through passageways 82 and 83 to the annular passageway 84 which opens toward the manifold 63. Then the flow passes through an opening to passageway 76 on one side of the eccentricity line G through the manifold passages 78, 79 to one of the openings 77 which is in communication with one of the cells 80 between the rotor and stator.Meanwhile, one of the cells 80 on the other side of the eccentricity line G communicates back to the appropriate passageway 76 and back through the manifold 63 to the exhaust passageways 74, 75 and 85 to exhaust.

Fig. 1 2 shows a portion of the right-hand end of Fig. 1 where the same parts are given the same reference numbers. Otherwise, the device operates as described in connection with Fig. 1. However, in Fig. 1 2 there has been added a pressure plate 90 inserted in a suitable recess in the end cap 240, and the end cap is pushed toward the left as viewed in Fig. 12 by means of pressure admitted through lines 91, connected with the exhaust 45, and line 92 connected with the intake 30. Each of the lines 91 and 92 has adjacent the pressure loading plate 90 a ball check valve 93 so that the loading plate 90 is always pressed inwardly toward the manifold 23 and the gerotor set 22 beyond it. This provides a head force towards the manifold and rotor set. This will take care of any wear between the engaging rubbing portions 22 and 23.

Fig. 13 also shows a portion of the righthand end of Fig. 1 and all of the same parts are given the same reference characters. The added feature here is a pressure loaded commutator ring 95 which extends inwardly, toward the left in Fig. 13, against a shoulder 96 with a wave spring 97 circular in shape and pressed between the commutator ring and the shoulder 96 to give an initial pressure. The wave spring is made of spring metal which weaves back and forth from a generally common plate as one goes around the circle. A seal 98 prevents leakage between the parts.

There is provided a pin connection 99 which as seen in Fig. 1 3 is in general an axial extension of the splines 440b connecting the wobble stick 380 and the rotor of the gerotor set 22. This pin fits between the splines 440b and extends into a suitable opening 99a in a portion of the commutator ring. This pin connection is somewhat loose so as to use the rotational component of the rotor as a means of timing the opening and closing of the connection indicated in dot-dash lines in Fig.

Claims (11)

1. A rotary fluid pressure device comprising a housing, fluid inlet and outlet means in said housing, a gerotor set in said housing having an internally toothed member and a co-acting externally toothed member having a lesser number of teeth than said internally toothed member and having its axis positioned eccentrically relative to the axis of said internally toothed member, one of said members having rotational movement about its own axis and orbital movement about the axis of said other member while forming expanding and contracting cells between said members, a rigid elongated wobble stick having first and second end portions, a partially hollow shaft means connected to said first end portion of said wobble stick for rotating the same, means connecting said second end portion of said wobble stick to said member having rotational and orbital movement, two sets of passages positioned in said housing for communicating at all times part of said cells with one only of said fluid inlet and outlet means while communicating other of said cells with other of said fluid inlet and outlet means; and both of said sets of passages passing entirely through said gerotor set outside its central portion, whereby said central portion is open and said wobble stick can be of considerable size approaching the diameter of the hollow part of said partially hollow shaft means.

2. A rotary fluid pressure device as claimed in claim 1 wherein the areas of each of said passageways on opposite axial sides of said gerotor set are substantially equal, whereby a pressure balance exists on said gerotor set.

3. A rotary fluid pressure device as claimed in claim 1 or claim 2 wherein said gerotor set has spaced parallel radially flat faces, a wear plate having a radially flat side engaging one radially flat face of said gerotor set, a manifold plate having a radially flat side engaging the other radially flat face of said gerotor set, said wear plate having a continuous annular opening on its gerotor side in communication with one of said fluid inlet and outlet means, there being through openings in said gerotor set parallel to its axis and registering with said annular opening, and inlet and exhaust openings in said manifold registering with said through openings and so arranged that they communicate at one time with said expanding fluid cells and at another time with said contracting fluid cells.

4. A rotary fluid pressure device as claimed in any one of claims 1 to 3 wherein said passages include a or the manifold axially engaging against said gerotor set and an end cap axially engaging said manifold on the side opposite said gerotor set, means holding said cap against said manifold, there being a pressure loading plate in a central recess in said end cap, an annular wave spring between said loading plate and said end cap, pressure fluid connections in said end cap communicating with said passages and valves in said pressure fluid connections adjacent said pressure loading plate opening only toward said plate, whereby a head force is exerted on said plate toward said manifold and gerotor set.

5. A rotary fluid pressure device as claimed in any one of claims 1 to 3 wherein said passages include a or the manifold axially engaging against said gerotor set and an end cap axially engaging said manifold on the side opposite said gerotor set, means holding said cap against said manifold, said gerotor externally toothed member having a concentric recess on the side toward said manifold, said recess having a larger diameter portion axially outermost and a smaller axially innermost portion, a flat radially extending shoulder joining said two portions, a commutator ring having larger and smaller diameter portions respectively fitting snugly into said smaller diameter recess portion and spaced from said larger diameter recess portion and there providing a wall of one of said passages, a seal between said smaller diameter portions, an annular wave spring against said shoulder held in compression by said end cap, and a drive pin connection between said commutator ring and said externally toothed member.

6. A rotary fluid pressure device as claimed in claim 1 or claim 2 wherein one of said inlet and outlet means is located axially of said shaft at the end of said housing beyond said wobble stick second end.

7. A rotary fluid pressure device comprising a housing, fluid inlet and outlet means in said housing, a gerotor set in said housing having parallel side faces and having an internally toothed member, a co-acting externally toothed member having a lesser number of teeth than said internally toothed member and having its axis positioned eccentrically relative to the axis of said internally toothed member, one of said members rotating about its own axis and having orbital movement about the axis of said other member while forming expanding and contracting cells between said members, a rigid elongated wobble stick having first and second end portions, shaft means connected to said first end portion of said wobble stick for rotating the same, means connecting said second end portion of said wobble stick to said member having rotating and orbital movement, passages positioned in said housing for communicating at all times part of said cells with one only of said fluid inlet and outlet means while communicating other of said cells with other of said fluid inlet and outlet means, and said passages including a commutating ring on one of said gerotor side faces.

8. A rotary fluid pressure device substantially as herein described with reference to Figs. 1 to 7 of the accompanying drawings.

9. A rotary fluid pressure device as claimed in claim 8 and modified substantially as herein described with reference to Fig. 1 2 of the accompanying drawings.

1 0. A rotary fluid pressure device as claimed in claim 8 and modified substantially as herein described with reference to Fig. 1 3 of the accompanying drawings.

11. A rotary fluid pressure device substantially as herein described with reference to Figs. 8 to 11 of the accompanying drawings.