VANE PUMP WITH HYDROSTATIC PRESSURE PLATES

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit to U.S Provisional Application 63/681,398, filed on Aug. 9, 2024, the disclosure of which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to devices and methods for pressurizing and transferring fluids. More specifically, the present disclosure relates to methods and devices for axially centering a rotor of a vane pump to maintain efficient operation.

BACKGROUND

Vane pumps have been used as high-pressure hydraulic pumps in applications such as automotive and aviation industries. Vane pumps may utilize various configurations, such as unbalanced, balanced, high performance, double, and variable vane pumps, but share several common elements, like a rotor disposed on a shaft within a cam ring. The rotor has a plurality of slots that house vanes, and the vanes are configured to slide radially outward and inward within the slots. In unbalanced vane pumps the rotor is disposed eccentrically in a circular cam ring and in balanced vane pumps the rotor is centrally disposed within an elliptical cam ring. To operate, the shaft rotates the rotor within the cam ring. As the space between the rotor and cam ring changes, the vanes slide in and out to seal against the cam ring wall. The increasing and decreasing volume between vanes creates a high-or low-pressure system to pump fluid through the vane pump.

In some instances, contaminants within the pump, pressure perturbations, or other operational impacts may cause the rotor to become axially uncentered and forced against one of the plates used to retain the rotor and fluid being pumped. This may cause the pump to lose mechanical and volumetric efficiency. Further, operating in an axially uncentered state may cause the vane pump and rotor to gain heat, due to the rotor contacting one of the pressure plates and a restricted or nonexistent flow of cooling fluid to that side of the pump chamber. These operating conditions may increase degradation of pump components, which can shorten the pump's expected lifespan and service intervals, or require costly repairs.

SUMMARY

The present disclosure generally relates to a vane pump with hydrostatic pressure plates, or port plates, to retain a rotor in an axially centered position within the vane pump. The port plates are in fluid connection with a compression/exhaust zone of the vane pump and are configured to apply a centering axial thrust to the rotor. If the rotor becomes uncentered between the port plates, the port plate closest to the rotor is configured to provide a greater axial thrust than the port plate further from the rotor, resulting in the rotor moving towards a central position between the port plates.

A vane pump with port plates can extend the life expectancy and/or service intervals of a vane pump by preventing an uncentered rotor from contacting the plates. Additionally, a vane pump with self-centering port plates can optimize the mechanical and volumetric efficiency of a vane pump by maintaining the rotor in an optimal position. By preventing the rotor from moving too close to one of the plates, cooling flow is not restricted from one side of the pump. Further, a vane pump of the current disclosure can utilize its own high-pressure source to provide centering axial thrusts to the rotor, which may eliminate the need for an additional pump or high pressure source to center the rotor. Additionally, a vane pump of the present disclosure can center the rotor without the need of electronic position sensors, controls, valves, or intervention by a user.

In some implementations, a vane pump has a housing with a fluid inlet opening and a fluid outlet opening. A cam ring is positioned within a pumping chamber the housing. A rotor is positioned within the cam ring and is rotatable around a rotor axis. The rotor has a first and second rotor face that face in opposite axial directions. The rotor also defines a plurality of radial slots configured to receive vanes and permit the vanes to move radially outward and inward relative to the rotor such that the vanes maintain contact with an interior surface of the cam ring as the rotor is rotated. The vane pump also comprises a first and second port plate, each having a first and second axial rotor face that oppose the first and second axial rotor faces and enclose opposite axial ends of the pumping chamber. The first and second port plates both define at least one inlet port in fluid communication with the fluid inlet opening and suction zone of the pumping chamber. The first and second port plates also both define at least one outlet port in fluid communication with the fluid outlet opening and compression/exhaust zoner of the pumping chamber. The vane pump also has a pressurization arrangement that uses pressure generated in the compression/exhaust zone to center the rotor between the first and second port plates. The pressurization arrangement increases axial thrust applied to the second axial rotor face and decrease axial thrust applied to the first rotor face when the rotor moves axially toward the second port plate. Similarly, the pressurization arrangement increases axial thrust applied to the first axial rotor face and decreases axial thrust applied to the second axial rotor face when the rotor moves axially toward the first port plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic axial view of a vane pump with port plates, according to an exemplary implementation.

FIG. 2 shows a schematic cross-sectional view of a vane pump with port plates, according to an exemplary implementation.

FIGS. 3A-3C show a rotor of the vane pump of FIGS. 1 and 2 in varying positions between port plates, according to an exemplary implementation.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a vane pump 100 with port plates 130/132, is shown according to an exemplary implementation. Throughout the following disclosure, “hydrostatic pressure plates” will be used synonymously with “port plates” for conciseness. The vane pump 100 comprises a pump housing 102. The housing 102 defines a fluid inlet opening 104 and a fluid outlet opening 106 and a cam ring 108 is positioned within the housing 102. The vane pump 100 further comprises a rotor 110 disposed within the cam ring 108 and between an opposing first and second port plate 130/132. The rotor 110 is rotatable around a rotor axis 112. As shown in FIGS. 1 and 2, the vane pump 100 is an unbalanced variable vane pump 100 comprising a circular cam ring 108 and a rotor 110 eccentrically disposed within the cam ring 108. However, in other implementations, the vane pump 100 can be a balanced vane pump comprising an elliptical cam ring 108 and centrally disposed rotor 110, a high-performance vane pump, double vane pump, or variable vane pump. A variable displacement vane pump 100 can further comprise a spacer 111 and yoke to shift the position of the cam ring 108 relative to the rotor 110 (e.g., with respect to the rotor axis 112 which is fixed relative to the housing 102), which changes the eccentricity of the rotor 110 within the cam ring 108 and the displacement of the pump 100.

A rotor shaft 114 is oriented along the rotor axis 112 and can be configured to be supported by bearings 116 supported by the housing 102. The rotor 110 has first and second axial rotor faces 122/124 that face in opposite axial directions as one another. The rotor 110 further defines a plurality of radial vane slots 126 configured to receive a plurality of vanes 128. The vanes 128 are configured to move within the vane slots 126 and slide between radially inward and radially outward positions to maintain contact with the cam ring 108 while the rotor 110 rotates. The vanes 128 can move from radially inward and outward positions, for example, by centripetal force, hydraulic pressure, or mechanical springs.

The first and second port plates 130/132 are positioned on either side of the rotor 110 such that first and second axial plate faces 134/136 oppose the first and second axial rotor face 122/124 respectively. The first and second port plates 130/132 connect to the housing 102 to enclose the rotor 110 in the cam ring 108. A pumping chamber 118 is defined within the housing 102 between the first and second axial plate faces 134/136. The rotor 110 and the cam ring 108 are within the pumping chamber 118. The pumping chamber 118 includes a low-pressure suction zone 142 (indicated by lighter shading in FIG. 1) in fluid communication with the fluid inlet opening 104 and a high pressure exhaust zone 144 (indicated by darker shading in FIG. 1) in fluid communication with the fluid outlet opening 106. The suction zone 142 creates a low pressure as the rotor 110 rotates clockwise and pumping regions between vanes 128 increase in volume due to the rotor 110 being positioned eccentrically within the cam ring 108 and the vanes 128 sliding radially outward. In contrast, the exhaust zone 144 creates a relatively higher pressure as the pumping regions between vanes 128 decrease in volume and the vanes 128 slide inward. The first and second port plates 130/132 further each define at least one inlet port 138 in fluid communication with the fluid inlet opening 104 and at least one outlet port 140 in fluid communication with the fluid outlet opening 106.

In an exemplary implementation the at least one inlet port 138 comprises two inlet ports concentrically extending partially around the port plates 130/132. The inlet ports 138 are radially spaced from each other and can be referred to as inner and outer inlet ports. As depicted, the inlet ports are curved slots centered about the rotor axis 112. Similarly, in an exemplary implementation, the at least one outlet port 140 comprises two outlet ports concentrically extending partially around the port plates 130/132 and positioned at an opposite side of the port plate 130/132 than the inlet ports 138. The outlet ports 140 are radially spaced from each other and can be referred to as inner and outer outlet ports. As depicted, the outlet ports are curved slots centered about the rotor axis 112. The inlet ports 138 and outlet ports 140 can be formed, for example, by a machining operation into the port plates 130/132. Generally, the inlet ports 138 are located in the suction zone 142 of the pump and the outlet ports 140 are located in the exhaust zone 144. As shown in FIG. 1, the inner ones of the inlet and outlet ports 138/140 are sized to align with the base of the vane slots 126. This allows pressure to be fed into the vane slots 126 to force the vanes 128 out to seal against the cam ring 108. An exemplary advantage of the present design is that the outlet ports 140 are in fluid communication with the fluid outlet opening 106, and thus able to provide a higher pressure to the base of the vane slots 126. This results in the vanes 128 being pushed out to seal against the cam ring 108 with greater force in the exhaust zone 144, where leakage between vanes 128 may be more likely to occur.

The first and second port plates 130/132 further provide a pressurization arrangement 145 that uses pressure generated in the exhaust zone 144 to center the rotor 110 between the first and second port plates 130/132. The pressurization arrangement 145 can comprise, for example, a first pressurization zone 146 defined between first axial rotor face 122 and the first axial plate face 134 and a second pressurization zone 148 defined between the second axial rotor face 124 and the second axial plate face 136. The pressurization zones 146, 148 can be annular and centered about the rotor axis 112 at a position radially between the bearing region of the shaft 114 and the inner ones of the inlet and outlet ports 138/140. In one example, the first and second port plates 130/132 can respectively define first and second grooves 150/152 (e.g., annular grooves) that respectively correspond to the first and second pressurization zones 146, 148. The first and second groove 150/152 can be formed, for example, by machining a circular groove into the port plates 130/132 radially inside the inner ones of the ports 138, 140. The first and second grooves 150/152 are in fluid communication with the exhaust zone 144 (e.g., the fluid outlet opening 106, and/or the inner outlet port 140, and/or the outer outlet port 140) via at least one first pressurized line 154 and at least one second pressurized line 156. In some implementations, the first and second pressurized lines 154/156 are entirely contained within the vane pump 100. In other implementations, the first and second pressurized lines 154/156 receive pressure from plumbing down-line of the fluid outlet opening 106. The first and second pressurized lines 154/156 provide a pressurized fluid to the first and second grooves 150/152, and can include passages 166 (shown in FIG. 3) in the port plates 130/132. A flow control orifice 158 is provided along each of the lines 154/156. As depicted, each passage 166 includes an orifice 158. The orifices 158 decrease the diameter of the passages 166, resulting in a restriction that limits flow rate through the passages to the grooves 150/152 and can reduce pressure within the grooves 150/152 slightly as compared to full outlet pressure. In an exemplary implementation, the orifice comprises a diameter of 0.045 inches.

An inner diameter seal ring 160 and outer diameter seal ring 162 concentrically surround the first and second groove 150/152 at a smaller and larger diameter than the first and second groove 150/152, respectively. In an exemplary implementation, the inner and outer seal rings 160/162 are portions of the port plate disposed at a closer clearance to the rotor 110 than the first and second grooves 150/152.

The flow path of fluid through the first and second grooves 150/152 is shown in FIGS. 1 and 2 by arrows. In general, the fluid flow paths (e.g., leak paths across the outer diameter seal) will vary a different regions of the first and second grooves 150/152. For example, the flow paths corresponding to the portions of the grooves 150/152 adjacent the low-pressure suction zone 142 are different than the portions of the grooves 150/52 adjacent the high-pressure exhaust zone 144. Relatively high pressure fluid is provided to the grooves 150/152 through the pressurized lines 154/156, through the orifices 158. Because there is a greater pressure within the grooves 150/152 than the low-pressure suction zone 142 of the pumping chamber 118, adjacent the suction zone 142 the fluid within the grooves 150/152 will flow/leak past the outer diameter seal ring 162 to the inner ones of the inlet ports 138. Adjacent the high-pressure exhaust zone 144, because there is a higher pressure in the at least one outlet port 140 than grooves 150/152 (due to the restrictions provided by the orifices 158), additional fluid flows from the inner ones of the outlet ports 140, past the outer diameter seal ring 162, and into the grooves 150/152. The bearings 116 are disposed in a lower pressure environment relative to the grooves 150/152, resulting in the fluid flowing past the inner diameter seal ring 160 and into the bearing drain 164 in both the suction zone 142 and exhaust zone 144. The fluid can then flow from the bearing drain 164 to the fluid inlet opening 104 or low pressure suction zone 142.

Referring now to FIGS. 3A-3C, a rotor 110 is shown in varying positions between port plates 130/132, according to an exemplary implementation. As previously described, the port plates 130/132 are in fluid communication with pressurized lines to provide a relatively high pressure of fluid to passages 166 within the port plates 130/132. The pressurized fluid then reaches the pressurization arrangement 145 providing the first and second pressurization zones 146/148. The pressurized fluid passes through the orifice 158 in the port plates 130/132. The pressurized fluid then moves out of the port plates 130/132 and into the first and second grooves 150/152. Normally, the pressure is the same at the first and second grooves 150/152 so the pressure regions help keep the rotor centered between the port plates. As previously mentioned, the rotor 110 may become axially uncentered for several reasons, such as contaminants within the pump, pressure perturbations, or other operational impacts. To allow the pump to operate efficiently and to prolong the life of the pump, it is desirable to move the rotor back towards a central location, where spacing between the first axial plate face 134 and first axial rotor face 122 is equal to the spacing between the second axial plate face 136 and second axial rotor face 124.

In FIG. 3A, the rotor 110 has been pushed towards or against the second port plate 132. Pressurized fluid flowing through the first groove 150 can move more freely past the inner and outer diameter seal rings 160/162 because the rotor 110 is shifted towards the second port plate 132. This allows the pressurized fluid to dissipate to the bearing drain and inlet port (not pictured). This exerts a relatively low pressure on the first axial rotor face 122 across the first pressurization zone 146, which can be the area defined by the first groove 150 and inner and outer diameter seal rings 160/162, resulting in a relatively low axial thrust applied to the first axial rotor face 122. Pressurized fluid moving through the second groove 152 has additional downstream flow restrictions due to the inner and outer diameter seal rings 160/162 being positioned close to, or against, the second axial rotor face 124. As a result, the pressure in the second groove 152 is greater than the pressure in the first groove 150. In other words, the second pressurization zone 148 is at a higher pressure than the first pressurization zone 146. This results in an axially imbalanced pressure applied to the first and second rotor faces 122/124, causing a net axial thrust to push the rotor 110 in the direction of the first port plate 130. As a practical matter, in most conditions the pressure in the second groove 152 increase to a level sufficiently higher than the first groove 150 to stop rotor drift before the rotor actually reaches the port plate 132 so that contact between the port plate 132 and the rotor is prevented (e.g., see FIG. 3B)

As described above, FIG. 3B shows the rotor 110 shifted towards the second port plate 132, but not shifted as far as depicted in FIG. 3A. In the position shown in FIG. 3B, the fluid flow through the first groove 150 (indicated by lighter shading in groove 150) is less restricted by the inner and outer diameter seal rings 160/162 than the fluid flow through the second groove 152 (indicated by darker shading in groove 152). Like described with regard to FIG. 3A, this results in a net axial thrust acting against the second axial rotor face 124 to push the rotor 110 towards the first port plate 130. Because the rotor 110 is spaced more evenly between the port plates 130/132, the net axial thrust is less than in FIG. 3A.

It will be appreciated that the pressurization arrangement also corrects rotor drift toward the port plate 130 in a similar manner. For example, the rotor drifts toward the port plate 130, leakage from the first groove 150 decreases due to tighter clearance between the sealing rings of the port plate 130 and rotor and leakage from the second groove 152 increases due to greater clearance between the sealing rings of the second port plate 132 and the rotor resulting in higher hydraulic thrust on the side of the rotor facing the first groove 150 as compared to the side of the rotor facing the second groove 152. This unbalance in hydraulic load assist in centering the rotor by forcing the rotor away from the first port plate 130 back toward center.

FIG. 3C shows the rotor 110 in an ideal operating position, evenly spaced between the port plates 130/132. In this position, the spacing between the axial rotor faces 122/124 and inner and outer diameter seal rings 160/162 are equal (indicated by the same shading in both grooves 150 and 152), resulting in equal and opposing pressures and axial thrusts being applied to the axial rotor faces 122/124 via the pressurization arrangement 145 of the port plates 130/132. Subsequent movement of the rotor 110 will then result in an unbalanced thrust to push the rotor back towards a centered position, as previously discussed.