Vane pump

Abstract

To provide a vane pump that can prevent air bubbles from occurring in a back pressure chamber.SOLUTION: A vane pump uses water or aqueous liquid as fluid. A first side plate is provided with a first back pressure groove 15 provided so as to be capable of communicating with a back pressure chamber 14. The first back pressure groove 15 is provided with a first concave part 17 provided at a position opposed to a suction groove, a discharge groove 16, and a first thin groove 18 establishing communication between the first concave part 17 and the discharge groove 16. A second side plate is provided with a second back pressure groove provided so as to be capable of communicating with the back pressure chamber 14. The second back pressure groove is provided with the suction groove, a second concave part provided at a position opposed to the discharge groove 16, and a second thin groove establishing communication between the suction groove and the second concave part. The first thin groove 18 and the second thin groove are formed so as to be thinner than the discharge groove 16 and the suction groove.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a vane pump, and more particularly to a vane pump that uses water or an aqueous liquid as a fluid. [Background technology]

[0002] Conventionally, there has been a vane pump. A vane pump has a main shaft and a rotor that rotates when the main shaft rotates. Rotation of the main shaft draws fluid into the rotor and discharges the fluid out of the rotor, thereby pushing out the fluid. The rotor body has vane slots formed at intervals along the circumferential direction, and vanes are inserted into the vane slots by elastic members so as to be able to freely protrude and retract from the rotor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-5951 Summary of the Invention [Problem to be solved by the invention]

[0004] A vane pump is arranged inside a vane motor or the like, with a cam ring containing a rotor sandwiched between a pair of left and right side plates, and the side plates are formed with a suction groove for supplying fluid and a discharge groove for discharging fluid.

[0005] In a vane pump, as the rotor rotates, first the vanes are compressed into the vane slots, compressing the fluid in the back pressure chamber located inside the vane slots and trapping the discharge pressure. Next, as the rotor rotates, the back pressure chamber connects to the suction groove, sucking the fluid into the back pressure chamber. Then, as the rotor rotates further, the back pressure chamber separates from the suction groove and connects to the discharge groove, discharging the fluid in the back pressure chamber into the discharge groove.

[0006] In conventional vane pumps, when the back pressure chamber 140 leaves the suction groove 210 and connects to the discharge groove 160, the discharge groove 160 side is under high pressure, and therefore there is a possibility that fluid will spray J from the high-pressure discharge groove 160 into the back pressure chamber 140, which has a lower pressure than the discharge groove 160.

[0007] If the fluid being pumped by the vane pump is oil, the occurrence of this ejection J is not thought to cause any particular problems, but if the fluid is water or a water-like liquid, the ejection J will cause bubbles B1 to form in the back pressure chamber 140. The bubbles B1 will burst E when exposed to high pressure on the discharge groove 160 side, and the impact of the bubbles B1 bursting can cause damage to the surface of the side plate (see Figure 10).

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vane pump that can prevent air bubbles from being generated in a back pressure chamber. [Means for solving the problem]

[0009] The present invention relates to a vane pump for use with water or an aqueous liquid as a fluid, and includes a main shaft, a rotor, a cam ring having a housing portion for the rotor provided inside, and first and second side plates provided to sandwich the cam ring. The rotor has a shaft hole through which the main shaft passes, vane slots provided intermittently in the circumferential direction, and vanes inserted into the vane slots so as to be able to freely appear and disappear. A back pressure chamber is provided in the vane slot, and the first side plate is provided with a first back pressure groove provided so as to be able to communicate with the back pressure chamber. the first back pressure groove is provided with a first recess provided at a position opposite the suction groove, a discharge groove, and a first narrow groove connecting the first recess and the discharge groove; the second side plate is provided with a second back pressure groove provided so as to be able to communicate with the back pressure chamber; the second back pressure groove is provided with the suction groove, a second recess provided at a position opposite the discharge groove, and a second narrow groove connecting the suction groove and the second recess, and the first narrow groove and the second narrow groove are formed narrower than the discharge groove and the suction groove.

[0010] In addition, the present invention may further provide a third narrow groove in each of the first and second side plates, the third narrow groove being parallel to the discharge groove or the second recess, and the third narrow groove being narrower than the discharge groove and the suction groove. In addition, the present invention may further provide a fourth narrow groove in each of the first backpressure grooves and a fifth narrow groove in each of the second backpressure grooves, the fourth narrow groove communicating with the first recess and being located further rearward of the first recess in the direction of rotation of the rotor, and the fifth narrow groove communicating with the suction groove and being located further rearward of the suction groove in the direction of rotation of the rotor, and the fourth narrow groove and the fifth narrow groove being narrower than the discharge groove and the suction groove. In addition, the present invention can form the cross-sectional area of ​​each of the narrow grooves to be 0.1% to 1.0% of the cross-sectional area calculated from the hydraulic diameter of the first recess.In addition, the present invention can form the cross-sectional area of ​​each of the narrow grooves to be 0.1% to 20% of the cross-sectional area calculated from the hydraulic diameter of the discharge groove.

[0011] In addition, although the expressions "first," "second," "third," "fourth," and "fifth" are used in the present invention, these expressions are used merely to clearly distinguish each configuration of the present invention, and the numbers and order thereof have no particular meaning. [Effects of the Invention]

[0012] The present invention prevents bubbles from being generated in the back pressure chamber by providing a first narrow groove in the first side plate that connects the first recess and the discharge groove, and by providing a second narrow groove in the second side plate that connects the suction groove and the second recess. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of an embodiment of the present invention. [Figure 2] 6A and 6B are six views of a tip plate in an embodiment of the present invention, where (a) is a front view, (b) is a back view, (c) is a left side view, (d) is a right side view, (e) is a plan view, and (f) is a bottom view. [Figure 3] FIG. 3 is an enlarged cross-sectional view of FIG. 2(a) combined with IIIa-O-IIIb. [Figure 4] FIG. 4 is an enlarged cross-sectional view of FIG. 2(a) taken along line IV-IV. [Figure 5] 6A and 6B are six views of a base end plate according to an embodiment of the present invention, in which (a) is a front view, (b) is a back view, (c) is a left side view, (d) is a right side view, (e) is a plan view, and (f) is a bottom view. [Figure 6] FIG. 6 is an enlarged cross-sectional view of FIG. 5(a) combined with VIa-O-VIb. [Figure 7] FIG. 7 is an enlarged cross-sectional view taken along line VII-VII of FIG. 5(a). [Figure 8] FIG. 4 is an enlarged view of a back pressure groove in the embodiment. [Figure 9] 5A and 5B are diagrams showing pressure changes in a back pressure chamber when a fluid is suctioned and discharged in an embodiment of the present invention, where FIG. 5A is a graph of pressure changes, and FIG. 5B is a schematic diagram showing the suction and discharge of a fluid. [Figure 10]1A and 1B are schematic diagrams showing pressure changes in a back pressure chamber when a fluid is suctioned and discharged in a conventional vane pump, where (a) is a graph of pressure changes, and (b) is a schematic diagram showing the suction and discharge of the fluid. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described with reference to Figures 1 to 9. First, the configuration of this embodiment will be described with reference to Figures 1 to 8. The vane pump 1 includes a main shaft 2, a rotor 3, a cam ring 4, and a side plate 5, and the fluid to be pumped is water.

[0015] The cam ring 4 has an accommodation portion 6 formed therein for accommodating the rotor 3. Two grooves 7 and 8 are formed on the outer periphery of the cam ring 4. The groove 7 is connected to a suction port (not shown) that is connected to a tank (not shown) in which a fluid is stored, and the groove 8 is connected to a discharge port (not shown). The cam ring 4 has communication holes (not shown) that connect the grooves 7 and 8 to the accommodation portion 6.

[0016] The rotor 3 has a rotor body 11 provided with a shaft hole 9 through which the main shaft 2 is inserted and vane slots 10 provided intermittently in the circumferential direction, and vanes 12 inserted so as to be able to freely protrude and retract into the vane slots 10. In this embodiment, the rotor 3 has an elastic member 13, such as a coil spring, for inserting the vanes 12 so as to be able to protrude and retract into the vane slots 10. A back pressure chamber 14 is provided on the inner side of the vane slots 10 partitioned by the vanes 12. The fluid pressure inside the rotor 3 is high on the side of a discharge groove 16 (described later) and low on the side of a suction groove 21 (described later).

[0017] The side plates 5 are provided so as to sandwich the cam ring 4, that is, provided as a pair (hereinafter referred to as a distal end side plate 5A and a proximal end side plate 5B, respectively).

[0018] The tip-side plate 5A is provided with an axial hole 9 and a back pressure groove 15 that is provided so as to be able to communicate with the back pressure chamber 14. The back pressure groove 15 is composed of a discharge groove 16, a recess 17 (hereinafter referred to as a suction-side recess 17), and a narrow groove 18 (hereinafter referred to as a communicating narrow groove 18). In this embodiment, the back pressure groove 15 is provided in two locations, and a narrow groove 19 (hereinafter referred to as a side narrow groove 19) is also provided.

[0019] The discharge groove 16 is provided to discharge the fluid from the back pressure chamber 14, and is connected to a discharge side port (not shown) via the groove portion 8. The suction side recess 17 is provided at a position opposite to the suction groove 21 (described later) across the rotor 3. In this embodiment, the suction side recess 17 is formed in substantially the same shape as the suction groove 21, except that it has a closed end.

[0020] The communicating narrow groove 18 communicates between the suction side recess 17 and the discharge groove 16. The side narrow groove 19 is formed so as to communicate with the suction side recess 17 and to be located rearward of the suction side recess 17 in the rotation direction A of the rotor 3.

[0021] The base-end plate 5B is provided with a back pressure groove 20 that is provided so as to be able to communicate with the axial hole 9 and the back pressure chamber 14. The back pressure groove 20 is composed of a suction groove 21, a recess 22 (hereinafter referred to as the discharge-side recess 22), and a narrow groove 23 (hereinafter referred to as the communicating narrow groove 23). In this embodiment, the back pressure groove 20 is provided in two locations, similar to the back pressure groove 15, and further includes a narrow groove 24 (hereinafter referred to as the side narrow groove 24).

[0022] The suction groove 21 is provided to suck fluid into the back pressure chamber 14, and is connected via the groove portion 7 to a suction side port (not shown) that is connected to a tank (not shown) in which the fluid is stored. The discharge side recess 22 is provided at a position opposite to the discharge groove 16 across the rotor 3, and in this embodiment, the discharge side recess 22 is formed in approximately the same shape as the discharge groove 16, except that it has a closed end.

[0023] The narrow communicating groove 23 communicates between the suction groove 21 and the discharge-side recess 22. That is, in this embodiment, the discharge groove 16 and the suction groove 21 communicate with each other via the narrow communicating grooves 18 and 23 and the back pressure chamber 14. The narrow side groove 24 is formed so as to communicate with the suction groove 21 and to be located rearward of the suction groove 21 in the rotation direction A of the rotor 3. In this embodiment, the narrow side groove 24 is provided in a position opposite the narrow side groove 19.

[0024] In this embodiment, narrow grooves 25 (hereinafter referred to as peripheral narrow grooves 25) are provided in each side plate 5. The peripheral narrow grooves 25 are provided in parallel with the discharge grooves 16 or discharge-side recesses 22 located on the high-pressure side on the outer periphery thereof, and in this embodiment, the peripheral narrow grooves 25 provided in each side plate 5 are provided at positions facing each other.

[0025] A low-pressure chamber 26 communicating with groove 7 and a high-pressure chamber 27 communicating with groove 8 are formed in housing 6, and as rotor 3 rotates, the spaces formed between vanes 12 move back and forth between low-pressure chamber 26 and high-pressure chamber 27. Therefore, when this space communicates with high-pressure chamber 27 via low-pressure chamber 26, fluid may be ejected from high-pressure chamber 27 into this space, generating bubbles. These bubbles may then be exposed to high pressure, potentially causing similar problems. By connecting this space with outer circumferential narrow groove 25, it is possible to gradually increase the fluid pressure in this space, as with communicating narrow grooves 18 and 23, thereby preventing the fluid from ejecting.

[0026] Each of the narrow grooves 18, 19, 23, 24, and 25 is formed narrower than the discharge groove 16 and the suction groove 21, and its cross-sectional area is appropriately selected within a range in which the drop in pressure on the discharge groove 16 side caused by each of the narrow grooves 18, 19, 23, 24, and 25 does not interfere with the operation of the vane pump 1. Preferably, the cross-sectional area calculated from the hydraulic diameter is 0.1% to 1.0% of the cross-sectional area of ​​the suction side recess 17 or 0.1% to 20% of the cross-sectional area of ​​the discharge groove 16.

[0027] Next, the suction and discharge of fluid in this embodiment will be described with reference to Fig. 9. In Fig. 9 and Fig. 10, the pressure change is shown by the shade of color, with darker colors indicating higher pressure and lighter colors indicating lower pressure. (1) By rotating the main shaft 2, the rotor 3 rotates, and the inner wall of the cam ring 4 pushes the vane 12 into the vane slot 10, trapping the discharge pressure in the back pressure chamber 14. As a result, the pressure inside the back pressure chamber 14 becomes high.

[0028] (2) When the main shaft 2 is further rotated, the back pressure chamber 14 communicates with the side narrow grooves 19 and 24. Because the side narrow grooves 19 and 24 communicate with the suction side recess 17 or the suction groove 21, they are at a low pressure, just like the suction side recess 17 and the suction groove 21, and the fluid pressure in the back pressure chamber 14 escapes to the side narrow grooves 19 and 24, gradually decreasing.

[0029] (3) When the main shaft 2 is further rotated, the back pressure chamber 14 communicates with the suction groove 21 and the suction-side recess 17. As a result, fluid is sucked into the back pressure chamber 14 from the suction port via the suction groove 21. At this time, the fluid pressure in the back pressure chamber 14 is low, just like the suction-side recess 17 and the suction groove 21.

[0030] In this case, in conventional vane pumps, back pressure chamber 140, which is confined in discharge pressure and has a high pressure, communicates with suction groove 210, which has a low pressure, causing fluid to be sprayed from back pressure chamber 140 to suction groove 210. This spraying can cause bubbles B2 to form in back pressure chamber 140, and when bubbles B2 are exposed to the high pressure of discharge groove 160, they can burst E, potentially damaging the side plate (see Figure 10). However, in this embodiment, since side narrow groove 24 communicates with back pressure chamber 14, the pressure difference between back pressure chamber 14 and suction side recess 17 and suction groove 21 can be reduced, making it possible to more effectively prevent the generation of bubbles.

[0031] (4) When the main shaft 2 is further rotated, the back pressure chamber 14 communicates with the narrow communicating grooves 18 and 23. When the main shaft 2 is then further rotated, the back pressure chamber 14 communicates with the discharge groove 16 and the discharge-side recess 22. Then, the high-pressure fluid in the back pressure chamber 14 is discharged into the discharge groove 16.

[0032] At this time, the narrow communicating grooves 18 communicate the suction-side recess 17, which, like the suction grooves 21, belongs to the low-pressure side, with the discharge grooves 16, which belong to the high-pressure side, and the narrow communicating grooves 23 communicate the suction grooves 21, which belongs to the low-pressure side, with the discharge-side recess 22, which belongs to the high-pressure side. Therefore, the fluid pressure in the narrow communicating grooves 18 and 23 transitions from low to high along the rotation direction A of the rotor. Therefore, as the rotor 3 rotates, the fluid pressure in the back pressure chamber 14 also gradually increases. This reduces the differential pressure between the back pressure chamber 14 and the discharge grooves 16, preventing the discharge grooves 16 from ejecting fluid into the back pressure chamber 14 and preventing the generation of bubbles.

[0033] (5) By repeating the above steps, the fluid is sent from the suction port side to the discharge port side.

[0034] Therefore, in the vane pump 1 of this embodiment, the narrow communicating grooves 18 and 23 are provided, so that the fluid is prevented from being ejected from the discharge groove 16 into the back pressure chamber 14, and the generation of bubbles can be prevented.

[0035] While the present invention has been described based on the above embodiment, it is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the invention. For example, in the above embodiment, the fluid in the vane pump 1 is water, but it is also possible to use an aqueous liquid having a viscosity approximately equal to that of water as the fluid. [Explanation of symbols]

[0036] 1 vane pump 2 main shaft 3 rotor 4 Cam ring 5 Side plate 5A Tip plate 5B base end plate 6 accommodation portion 7 groove portion 8 Groove 9 Shaft hole 10 Vane slot 11 rotor body 12 vane 13 elastic member 14 Back pressure chamber 15 Back pressure groove 16 Discharge groove 17 suction side recess 18 communicating narrow groove 19 side narrow groove 20 back pressure groove 21 suction groove 22 discharge side recess 23 communicating narrow groove 24 side narrow groove 25 peripheral narrow groove 26 Low pressure chamber 27 High pressure chamber 140 Back pressure chamber 160 Discharge groove 210 Suction groove A Rotation direction B1 Bubble B2 Bubble E Burst J squirt

Claims

1. A vane pump that uses water or an aqueous liquid as a fluid, a main shaft, a rotor, a cam ring having an accommodating portion for the rotor provided therein, and a first side plate and a second side plate provided to sandwich the cam ring; The rotor has a shaft hole through which a main shaft is inserted, vane slots provided at intervals in the circumferential direction, and vanes inserted into the vane slots so as to be able to freely appear and disappear, and a back pressure chamber is provided in the vane slot, a first back pressure groove provided in the first side plate and capable of communicating with the back pressure chamber, the first back pressure groove including a first recess provided at a position facing the suction groove, a discharge groove, and a first narrow groove communicating between the first recess and the discharge groove; a second back pressure groove provided in the second side plate so as to be able to communicate with the back pressure chamber, the second back pressure groove including the suction groove, a second recess provided at a position facing the discharge groove, and a second narrow groove communicating between the suction groove and the second recess, The vane pump is characterized in that the first narrow groove and the second narrow groove are formed narrower than the discharge groove and the suction groove.

2. The first and second side plates are further provided with third narrow grooves, the third narrow groove is provided in parallel with the ejection groove or the second recess, 2. The vane pump according to claim 1, wherein the third narrow groove is narrower than the discharge groove and the suction groove.

3. The first back pressure groove is further provided with a fourth narrow groove, the second back pressure groove is further provided with a fifth narrow groove, the fourth narrow groove is in communication with the first recess and is disposed rearward of the first recess in the direction of rotation of the rotor, the fifth narrow groove is in communication with the suction groove and is disposed rearward of the suction groove in the direction of rotation of the rotor, 2. The vane pump according to claim 1, wherein the fourth narrow groove and the fifth narrow groove are narrower than the discharge groove and the suction groove.

4. The first and second side plates are further provided with third narrow grooves, the third narrow groove is provided in parallel with the ejection groove or the second recess, 4. The vane pump according to claim 3, wherein the third narrow groove is narrower than the discharge groove and the suction groove.

5. 5. The vane pump according to claim 1, wherein the cross-sectional area of ​​each of the narrow grooves is 0.1% to 1.0% of the cross-sectional area calculated from the hydraulic diameter of the first recess.

6. 5. The vane pump according to claim 1, wherein the cross-sectional area of ​​each of the narrow grooves is 0.1% to 20% of the cross-sectional area calculated from the hydraulic diameter of the discharge groove.

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