vane pump
The vane pump addresses sliding resistance issues by using annular protrusions to create a stable gap between the rotor and side plates, ensuring smooth operation and reduced friction.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NACHI FUJIKOSHI CORP
- Filing Date
- 2024-10-23
- Publication Date
- 2026-05-11
AI Technical Summary
The vane pump in existing technologies faces issues with increased sliding resistance due to variations in orifice diameter during machining and changes in oil viscosity with temperature, leading to excessive pressure differences across the orifice.
A vane pump design that incorporates continuous or discontinuous annular protrusions on the sliding surfaces of the side plates and rotor, forming a gap to reduce sliding resistance by ensuring a stable oil film between the rotor and side plates.
The design reduces sliding resistance by maintaining a consistent gap, allowing the rotor to move freely without excessive pressure, thereby minimizing friction and preventing seizure.
Smart Images
Figure 2026075925000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a vane pump used as a hydraulic generating pump for an automotive continuously variable transmission (CVT) or a lubrication cooling pump for an electric vehicle (EV).
Background Art
[0002] A vane pump includes a rotor rotatable about an axis, a cam ring, and a plurality of vanes. The rotor is housed within the cam ring, and a plurality of vane grooves are formed radially on the outer peripheral surface. The plurality of vanes are fitted into the plurality of vane grooves and project slidably from the rotating rotor. The rotor also has a vane back pressure chamber formed on the shaft side (inner side) of the vane groove to conduct back pressure to the vanes.
[0003] The vanes project radially from the rotor due to centrifugal force associated with the rotation of the rotor and the back pressure introduced into the vane back pressure chamber of the rotor, and slide along the inner peripheral surface of the cam ring. Thereby, the vane pump performs a pumping action due to a change in the volume of the pump chamber partitioned by adjacent vanes, the rotor, and the cam ring (for example, Patent Document 1).
[0004] The vane pump of Patent Document 1 has a side plate constituting the side wall of the pump chamber, and discharges pressure is introduced to the back surface of the side plate to apply back pressure. An orifice communicating with the vane back pressure chamber of the rotor is provided in the side plate. Thereby, the discharge pressure introduced to the back surface of the side plate is introduced into the vane back pressure chamber of the rotor through the orifice.
[0005] Therefore, if there is oil leakage between the rotor and the side plate, a differential pressure corresponding to the leakage amount (the leakage amount of the pump chamber) is generated before and after the orifice, and the side plate is pressed against the rotor by this differential pressure.
[0006] As a result, in the vane pump described in Patent Document 1, the force (pressure force) that the side plates exert on the rotor changes according to the differential pressure, ensuring that the pressure force of the side plates is neither excessive nor insufficient in accordance with the amount of leakage in the pump chamber. [Prior art documents] [Patent Documents]
[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-58266 [Overview of the project] [Problems that the invention aims to solve]
[0008] However, in the vane pump described in Patent Document 1, the orifice is provided in the side plate, which makes the side plate difficult to process. If variations in the orifice diameter occur due to the processing, it becomes difficult to control the magnitude of the differential pressure generated before and after the orifice. Also, when the oil temperature changes, the viscosity of the oil changes, which in turn changes the amount of leakage. Therefore, when the oil temperature changes, the differential pressure generated before and after the orifice changes in accordance with the amount of leakage.
[0009] Therefore, variations in the orifice diameter due to machining of the side plates and changes in oil temperature can cause, for example, excessive pressure differences across the orifice. This increases the pressure on the side plates, causing the rotor to slide while pressed against them, resulting in increased sliding resistance.
[0010] In view of these problems, the present invention aims to provide a vane pump that can reduce the sliding resistance of the rotor by securing a gap between the side plate and the rotor. [Means for solving the problem]
[0011] To solve the above problems, a typical configuration of the vane pump according to the present invention includes a rotor rotatable around an axis, a plurality of vane grooves formed radially on the outer circumferential surface of the rotor, a plurality of vanes fitted into the plurality of vane grooves and slidably protruding from the rotating rotor, two side plates arranged on both sides of the rotor and facing the side surface of the rotor, and back pressure grooves formed in the side plates that can communicate with the axial side of the vane grooves of the rotor and through which discharge pressure is guided, wherein the two side plates or the rotor have continuous or discontinuous annular protrusions formed on the sliding surfaces with the opposing mating part and located axially closer to the back pressure groove.
[0012] The above-mentioned protrusions are preferably formed by coating or plating.
[0013] Preferably, the sliding surface described above has an annular groove formed therein, and the protrusions are formed by fitting a shim ring or a ring-shaped elastic body into the groove so that it protrudes from the groove. [Effects of the Invention]
[0014] According to the present invention, it is possible to provide a vane pump that can reduce the sliding resistance of the rotor by ensuring a gap between the side plate and the rotor. [Brief explanation of the drawing]
[0015] [Figure 1] This is a schematic diagram showing a cross-section of a vane pump in an embodiment of the present invention. [Figure 2] This diagram shows the main components of the vane pump shown in Figure 1. [Figure 3] This is a schematic diagram illustrating the principle by which a rotor moves due to pressure balance. [Figure 4] Figure 1 is a schematic diagram illustrating the behavior of the rotor when it is shifted to one side plate. [Modes for carrying out the invention]
[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in such embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals to omit redundant descriptions, and elements not directly related to the present invention are not shown.
[0017] FIG. 1 is a schematic view showing a cross-section of a vane pump 100 according to an embodiment of the present invention. FIG. 2 is a view showing a main part of the vane pump 100 of FIG. 1. The vane pump 100 is used as a hydraulic generation pump for a continuously variable transmission (CVT) for automobiles or a lubrication cooling pump for an EV vehicle.
[0018] The vane pump includes a rotor 102, a cam ring 104, and a plurality of vanes 106 (see FIG. 2(a)). Note that FIG. 2(a) is a cross-sectional view taken along the line A-A of the vane pump 100 of FIG. 1. The rotor 102 is housed inside the cam ring 104, and a plurality of vane grooves 108 are radially formed on the outer peripheral surface as shown in FIG. 2(a). The rotor 102 is rotatable about a shaft 110.
[0019] The plurality of vanes 106 are fitted into the plurality of vane grooves 108 of the rotor 102, are in a state where they can move in and out in the radial direction of the rotor 102, and project slidably from the rotating rotor 102. As a result, the plurality of vanes 106 rotate and move along the inside of the cam ring 104 while moving in and out toward the cam ring 104 as the rotor 102 rotates.
[0020] The rotor 102 also has a vane extrusion chamber (vane back pressure chamber 112). The vane back pressure chamber 112 is formed on the shaft 110 side (inside) of the vane groove 108 and guides back pressure to the vane 106.
[0021] Furthermore, the vane pump 100 includes two side plates 114 and 116 (see FIG. 1). The side plates 114 and 116 have a substantially disc shape, are arranged on both sides of the rotor 102 as shown in FIG. 1, and face the sliding surfaces 118 and 120 which are the side surfaces of the rotor 102.
[0022] FIG. 2(b) is a view showing the side surface of the side plate 114 on the rotor 102 side, that is, the sliding surface 122. Suction ports 124 and 126, discharge ports 128 and 130, and back pressure grooves 132 and 134 are formed in the sliding surface 122 of the side plate 114.
[0023] After oil is sucked into the vane pump 100 through the suction port of the pump body (not shown) via the suction ports 124 and 126, the oil is sent in the direction of the rotor 102 as shown by the arrow B in FIG. 1. Further, the oil is sent to the pump chamber partitioned by the rotor 102 and the cam ring 104. The discharge ports 128 and 130 send the oil discharged from the pump chamber in the direction of the discharge port of the pump cover (not shown) as shown by the arrow C in FIG. 1.
[0024] As shown in FIG. 2(b), the back pressure grooves 132 and 134 are provided in an arc shape and face each other around the central hole 136 passing through the shaft 110 (see FIG. 2(a)). The back pressure grooves 132 and 134 are communicable with the vane back pressure chambers 112 formed on the shaft 110 side of the plurality of vane grooves 108 of the rotor 102.
[0025] Also, back pressure ports 138 and 140 are provided in the back pressure grooves 132 and 134 respectively as shown in FIG. 2(b). The back pressure grooves 132 and 134 communicate with the discharge ports 128 and 130 via the back pressure ports 138 and 140. Thereby, pressure oil (discharge pressure) from the discharge ports 128 and 130 is led to the back pressure grooves 132 and 134 of the side plate 114 (see the arrow D in FIG. 1).
[0026] The pressurized oil guided to the back pressure grooves 132 and 134 of the side plate 114 passes through the vane back pressure chamber 112 of the rotor 102, as shown by arrow E in Figure 1, to become the back pressure of the vane 106, and is then guided to the back pressure grooves 142 and 144 of the opposite side plate 116. The back pressure grooves 142 and 144 of the opposite side plate 116 are formed on the side surface 146 facing the rotor 102.
[0027] Therefore, the vane 106 is propelled radially away from the rotor 102 by the centrifugal force accompanying the rotation of the rotor 102 and the back pressure guided into the vane back pressure chamber 112 of the rotor 102, and slides along the inner circumferential surface of the cam ring 104. As a result, the vane pump 100 performs its pumping action by changing the volume of the pump chamber, which is partitioned by the adjacent vane 106 and the rotor 102 and cam ring 104.
[0028] In the vane pump 100, an oil film is formed in the gaps 148 and 150 between the rotor 102 and the two side plates 114 and 116 by introducing pressurized oil from back pressure grooves 132 and 134 and back pressure grooves 142 and 144. This reduces the sliding resistance of the rotating rotor 102 and prevents seizure. In other words, in the vane pump 100, the sliding resistance of the rotor 102 can be reduced by ensuring the gaps 148 and 150.
[0029] In the vane pump 100 of this embodiment, as shown in Figure 1, gaps 148 and 150 are secured by forming protrusions 152 and 154 on the sliding surfaces 122 and 146 of the side plates 114 and 116, respectively.
[0030] As shown in Figure 2(b), the protrusion 152 of the side plate 114 is a continuous annular shape and is located on the shaft 110 side (inward) of the sliding surface 122 than the back pressure grooves 132 and 134. Similarly, the protrusion 154 of the side plate 116 shown in Figure 1 is also a continuous annular shape and is located on the sliding surface 146 than the back pressure grooves 142 and 144.
[0031] As the protrusions 152 and 154 are continuous annular shapes, the gaps 148 and 150 can be reliably secured. However, the protrusions 152 and 154 may be discontinuous annular shapes as long as the gaps 148 and 150 can be reliably secured. Furthermore, since the protrusions 152 and 154 are located inside the back pressure grooves 132 and 134 of the sliding surfaces 122 and 146, they do not rub against the vanes 106 when the multiple vanes 106 slidably protrude from the rotating rotor 102, and thus do not hinder the movement of the vanes 106.
[0032] Furthermore, these protrusions 152 and 154 are formed, for example, by coating or plating. That is, areas other than the protrusions 152 and 154 can be masked and then coated with fluororesin or other materials, or chrome plated or nickel plated. This makes it possible to form small protrusions 152 and 154 on the sliding surfaces 122 and 146 of the side plates 114 and 116. The protrusions 152 and 154 have dimensions such as a width of 0.5 to 1.5 mm and a height (thickness) of 5 to 10 μm, for example. The gaps 148 and 150 between the rotor 102 and the side plates 114 and 116 have dimensions such as 12 to 15 μm, for example.
[0033] Figure 3 is a schematic diagram illustrating the principle by which the rotor 102 moves due to pressure balance. Here, the movement of the rotor 102 will be explained using a comparative example (conventional structure) vane pump 100A.
[0034] The vane pump 100A differs from the vane pump 100 described above in that the side plates 114A and 116A, which do not have protrusions 152 and 154, face the sliding surfaces 118 and 120 of the rotor 102.
[0035] In the vane pump 100A shown in Figure 3(a), the rotor 102 is located in a position (i.e., center) where the gaps 148 and 150 between it and the two side plates 114A and 116A are equal in size.
[0036] In the vane pump 100A, the rotor 102 is located in the center, so the pressure distribution Pa, Pb generated in the gap 148 and the pressure distribution Pc, Pd generated in the gap 150 are equal, resulting in a balanced state (pressure balance is maintained). The area of the pressure distribution Pa, Pb, Pc, Pd corresponds to the force generated between the sliding surfaces 118, 120 of the rotor 102 and the sliding surfaces 122, 146 of the side plates 114A, 116A.
[0037] In the vane pump 100A shown in Figure 3(b), the rotor 102 is located closer to the side plate 114A rather than in the center, and the gap 150 is larger than the gap 148. Here, the sizes of gaps 148 and 150 are inversely proportional to the pressure distribution Pa, Pb, Pc, and Pd.
[0038] Therefore, the pressure distributions Pc and Pd generated in the larger gap 150 are smaller than the pressure distributions Pa and Pb generated in the smaller gap 148. As a result, the rotor 102 is pushed back by the force F generated between the sliding surface 118 of the rotor 102 and the sliding surface 122 of the side plate 114A, and moves towards the center due to the pressure balance.
[0039] In the vane pump 100A shown in Figure 3(c), the rotor 102 is in contact with the side plate 114A, and the sliding surface 118 of the rotor 102, which is the pressure-receiving surface for pressurized oil, is blocked by the sliding surface 122 of the side plate 114A.
[0040] Therefore, in the vane pump 100A, pressurized oil is not directed into the gap 148, and thus no force F (see Figure 3(b)) is generated to push the rotor 102 back to the center. In other words, once the rotor 102 comes into contact with the side plates 114A and 116A, it cannot return to the center due to the pressure balance. As a result, the rotor 102 slides while being pressed against the side plate 114A, and the sliding resistance increases.
[0041] In contrast, in the vane pump 100 of this embodiment, even if the rotor 102 is pressed against either of the two side plates 114 and 116, the protrusions 152 and 154 ensure gaps 148 and 150. Therefore, the sliding surfaces 118 and 120 of the rotor 102, which are the pressure-receiving surfaces for the pressurized oil, are not blocked (see Figure 4).
[0042] Figure 4 is a schematic diagram illustrating the behavior of the rotor 102 when it is shifted to one side plate 114 as shown in Figure 1. In the vane pump 100, even when the rotor 102 is pressed against the side plate 114, it strikes the protrusion 152 of the side plate 114, ensuring a gap 148. As a result, pressurized oil is guided into the gap 148, ensuring a pressure distribution.
[0043] As a result, a force F is generated between the sliding surface 118 of the rotor 102 and the sliding surface 122 of the side plate 114, and the rotor 102 is pushed back by the force F and can move towards the center due to the pressure balance. Even when the rotor 102 is pressed against the side plate 116, the gap 150 is secured by the protrusion 154, so the pressure-receiving surface does not disappear, and the rotor 102 moves towards the center.
[0044] As a result, in the vane pump 100, even if the rotor 102 is pressed against either of the two side plates 114 or 116, the rotor 102 will not remain pressed against the side plates 114 or 116, thereby reducing the sliding resistance of the rotor 102.
[0045] The above-mentioned protrusions 152 and 154 are formed by coating or plating on the sliding surfaces 122 and 146 of the side plates 114 and 116, but are not limited to this. For example, annular grooves may be formed on the sliding surfaces 122 and 146, and protrusions 152 and 154 may be formed by fitting a separate part (e.g., a shim ring or a ring-shaped elastic body) into the grooves so that it protrudes from the grooves. In this way, protrusions 152 and 154 can be easily formed by fitting a separate part into the grooves of the sliding surfaces 122 and 146. Furthermore, maintenance of the protrusions 152 and 154 when they wear down is also easy. As an example of a separate part, a ring-shaped elastic body may be a PTFE ring.
[0046] Furthermore, the above-mentioned protrusions 152 and 154 may be formed on the sliding surfaces 118 and 120 of the rotor 102 instead of the sliding surfaces 122 and 146 of the side plates 114 and 116. Even in this case, a gap 148 and 150 is secured between the sliding surfaces 118 and 120 of the rotor 102 and the sliding surfaces 122 and 146 of the side plates 114 and 116, thereby reducing the sliding resistance of the rotor 102.
[0047] Therefore, with the vane pump 100, a simple configuration is used in which protrusions 152 and 154 are formed on the sliding surfaces 122 and 146 of the two side plates 114 and 116, or on the sliding surfaces 118 and 120 of the rotor 102, thereby securing gaps 148 and 150 between the side plates 114 and 116 and the rotor 102 and reducing the sliding resistance of the rotor 102.
[0048] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]
[0049] This invention can be used as a hydraulic pump for continuously variable transmissions (CVTs) in automobiles, or as a lubrication and cooling pump for electric vehicles (EVs). [Explanation of Symbols]
[0050] 100, 100A...Vane pump, 102...Rotor, 104...Cam ring, 106...Vane, 108...Vane groove, 110...Shaft, 112...Vane back pressure chamber, 114, 114A, 116, 116A...Side plate, 118, 120...Sliding surface of rotor, 122, 146...Sliding surface of side plate, 124, 126...Suction port, 128, 130...Discharge port, 132, 134, 142, 144...Back pressure groove, 136...Hole in side plate, 138, 140...Back pressure port, 148, 150...Gap, 152, 154...Protrusion on side plate
Claims
1. A rotor that can rotate around its axis, Multiple vane grooves are formed radially on the outer circumferential surface of the rotor, Multiple vanes fitted into the aforementioned multiple vane grooves and slidably protruding from the rotating rotor, The rotor is positioned on both sides and consists of two side plates facing the sides of the rotor, The side plate is formed and is capable of communicating with the axial side of the vane groove of the rotor, and includes a back pressure groove through which the discharge pressure is guided, A vane pump characterized in that the two side plates or the rotor have continuous or discontinuous annular protrusions formed on their sliding surfaces with the opposing mating surface, and located on the axial side of the back pressure groove.
2. The vane pump according to claim 1, characterized in that the aforementioned protrusions are formed by coating or plating.
3. The sliding surface has an annular groove formed therein. The vane pump according to claim 1, characterized in that the protrusion is formed by fitting a shim ring or a ring-shaped elastic body into the groove such that it protrudes from the groove.