JP2004232465A - Vane pump and vane motor of bidirectional type - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vane pump and a vane motor of a bidirectional type, bringing tip parts of vanes in change-over areas surely into contact with an inner face of a cam ring with appropriate force, regardless of normal rotation or reverse rotation of a rotor. <P>SOLUTION: Communicating holes 21a, 21b to make areas a<SB>1</SB>, b<SB>1</SB>in the cam ring 6 communicate with pressure chambers 23 are formed, and check valves 24 are disposed in the communication holes 21a, 21b. Pressure in the pressure chambers 23 is introduced into back pressure ports 25 positioned to the change-over areas c<SB>1</SB>to c<SB>4</SB>. A cam profile of the cam ring 6 positioned to the change-over areas c<SB>1</SB>to c<SB>4</SB>is in a shape of a circular arc of a complete round whose circular center is a center of a radial shape constituted of a plurality of vane housing grooves 10. Since projection amounts of the vanes 11 are fixed by the cam profile of the change-over areas c<SB>1</SB>to c<SB>4</SB>, the pumping operation by base parts of the vanes 11 is not performed. Therefore, trouble of sharp increase in pressure of the back pressure ports 25 is prevented. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The invention of this application relates to a bidirectional vane pump in which suction and discharge are switched by switching between normal rotation and reverse rotation of a rotor, and a bidirectional vane motor in which rotation of the rotor is switched between normal rotation and reverse rotation by switching between suction and discharge.
[0002]
[Prior art]
In general, a vane pump has a plurality of vanes attached to a rotor rotatably driven by a drive shaft so as to be able to advance and retreat in a radial direction. A rotating side wall member is disposed. Each vane on the rotor is guided to move forward and backward along the cam profile on the inner peripheral surface of the cam ring, and increases or decreases the volume of a pump chamber formed between adjacent vanes. In addition, in the side wall member, a region where the volume of the pump chamber is increased and a region where the volume of the pump chamber is reduced are provided with a pair of inlet / outlet ports, respectively. Is discharged from the inlet / outlet port.
[0003]
In addition, a vane pump that introduces the pressure of the hydraulic fluid to the bottom of the vane accommodating groove of the rotor in order to bring the tip of each vane into close contact with the inner peripheral surface of the cam ring with an appropriate force is also generally used. In this vane pump, a back pressure port is provided at a position of the side wall member facing the bottom of the vane accommodating groove of the rotor, and the back pressure port located in a region where the volume of the pump chamber is enlarged operates an inlet / outlet port on the suction side. The hydraulic fluid is introduced into the discharge side inlet / outlet port to the back pressure port in the region where the volume of the pump chamber is reduced by introducing the liquid and the switching region where the reduction region is switched to the expansion region.
[0004]
By the way, in recent years, development of a bi-directional vane pump having such a basic structure that can switch between suction and discharge by switching between forward rotation and reverse rotation of a rotor has been studied (for example, see Patent Document 1). .
[0005]
This conventional bidirectional vane pump is devised so that the discharge pressure is always introduced to the back pressure port in the switching area regardless of the forward rotation or the reverse rotation of the rotor. A communication path is provided between the pressure port and each of the inlet / outlet ports, and a check valve that allows only the flow of the hydraulic fluid to the exhaust pressure port side is provided in each of the communication paths. Therefore, in the case of this vane pump, the discharge pressure always acts on the back pressure port in the switching area due to the function of the check valve interposed in each communication path, and the tip of the vane separates from the inner surface of the cam ring in the switching area. The defect is eliminated.
[0006]
[Patent Document 1]
Published Japanese Utility Model Application No. 58-44495
[Problems to be solved by the invention]
In the case of this conventional bidirectional vane pump, since the inner surface of the cam ring is circular and the center of the circle formed by the inner surface and the center of the rotor are offset, the amount of protrusion of the vane in the switching region is switched. It changes continuously before and after the center. However, when the vane is pushed into the vane accommodating groove in the switching area, the communication paths between the back pressure port and the two inlet / outlet ports are respectively closed by the check valves. Would.
[0008]
For this reason, in the conventional vane pump, the tip of the vane is pressed against the inner surface of the cam ring by a strong force in the switching area, and the sliding resistance increases rapidly. Then, it is feared that the sudden increase in the sliding resistance hinders the smooth operation of the pump and causes early wear of the vane tip.
[0009]
At present, the development of a bidirectional vane motor is also under study, but if the basic structure is the same as that of the conventional vane pump, the same problem is expected to occur.
[0010]
Therefore, the invention of this application is to ensure that the tip of the vane can be brought into contact with the inner surface of the cam ring with an appropriate force in the switching area regardless of whether the rotor rotates forward or backward, An object of the present invention is to provide a bidirectional vane pump and a vane motor capable of obtaining a reliable operation without causing a sudden increase in sliding resistance.
[0011]
[Means for Solving the Problems]
As a means for solving the above-mentioned problem, the invention of the bi-directional vane pump of the present application provides a pump in a back pressure port located in a switching region between a region where the volume of the pump chamber is reduced and a region where the volume is expanded. A communication path for introducing the discharge pressure at the bottom of the chamber or the vane accommodating groove through a check valve is provided, and the cam profile of the cam ring located in the switching area is centered on the center of the radial shape formed by the plurality of vane accommodating grooves. In the shape of a perfect circle.
[0012]
In the case of the present invention, the discharge pressure is always introduced into the back pressure port located in the switching area regardless of the rotation direction of the rotor, but in the switching area, the amount of protrusion of the vane is constant due to the cam profile of the cam ring. Therefore, no pump action is performed at the bottom of the vane housing groove. For this reason, in the switching area, the pressure of the back pressure port does not suddenly increase, and therefore, reliable bidirectional operation of the pump can be obtained without increasing the sliding resistance of the vane.
[0013]
This bi-directional vane pump is a pressure-balanced pump in which two reduced areas in which the volume of the pump chamber is reduced and two expanded areas in which the volume of the pump chamber is expanded are arranged at diagonal positions in the cam ring. Desirably. In this case, the pump operation is balanced, silence is enhanced, and pulsation is prevented from occurring.
[0014]
Further, the one side wall member is disposed so as to be able to approach and separate in the axial direction with respect to the rotor, and a pressure force in the rotor direction is applied to the side wall member at a position facing the surface of the side wall opposite to the rotor. In addition, a communication hole and a check valve for introducing discharge pressure into the pressure chamber are provided in the side wall member, and the pressure in the pressure chamber is introduced to the bottom of the vane accommodating groove in the switching area. The communication hole and the pressure chamber may form a communication path, and the communication hole may form a back pressure port. In this case, since the pressure chamber and the communication hole for introducing the discharge pressure to the pressure chamber are shared with the communication path for introducing the discharge pressure to the back pressure port, the entire passage structure is greatly simplified. be able to.
[0015]
In addition, the invention of the bidirectional vane motor of this application includes a rotor connected to an output shaft, a plurality of vanes attached to the rotor so as to be able to advance and retreat in a radial direction, and a rotatable inner rotor. A cam ring for accommodating and guiding the movement of each of the vanes along a cam profile on an inner peripheral surface thereof, and forming a variable volume chamber between adjacent vanes; A side wall member, at least one pair of inlet / outlet ports formed at a position facing a region where the volume of the variable volume chamber is enlarged and a region where the volume of the variable volume chamber is reduced, and a vane housing of the rotor of the side wall member A back pressure port formed at a position facing the bottom of the groove to apply hydraulic fluid pressure to the base of the vane, and a switching area between an area where the volume of the variable volume chamber is reduced and an area where it is expanded. And a communication path for introducing a supply pressure to the located back pressure port via a check valve.The cam profile of the cam ring located in the switching area is formed by a plurality of vane receiving grooves. The center of the shape is formed as a perfect circular arc with the center of the circle.
[0016]
In the case of the present invention, the supply pressure is always introduced to the back pressure port located in the switching area regardless of the rotation direction of the rotor (regardless of which supply port the supply pressure is introduced to). Further, in the switching area, the amount of protrusion of the vane is constant due to the cam profile of the cam ring, so that no pump action is performed at the bottom of the vane receiving groove. Therefore, in the switching area, the pressure of the back pressure port does not increase rapidly, so that the tip of the vane can be brought into close contact with the cam ring at an appropriate pressure without causing a sudden increase in the sliding resistance of the vane.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
First, a first embodiment shown in FIGS. 1 to 6 will be described. This embodiment is an embodiment of a bidirectional vane pump according to the invention of the present application, and this vane pump is used, for example, for a hydraulic power source of a power steering device of a vehicle, and is used for changing a rotation direction of a drive shaft. The suction and the discharge are interchanged accordingly.
[0018]
In FIG. 2, 1 is a housing composed of a base block 2 and a cover 3, 4 is a drive shaft connected to a drive source (not shown), and 5 is a rotor integrally connected to the drive shaft 4. . The rotor 5 is arranged on the inner peripheral side of a perforated disk-shaped cam ring 6, and a front side plate 7 as a side wall member and a pressure plate 8 are arranged before and after the cam ring 6 in a superposed manner. The cam ring 6 accommodating the rotor 5 inside and these plates 7 and 8 are accommodated in a circular concave portion of the cover 3, and in this state, the rotation is restricted by the locating pin 9 to the base block 2. Note that the displacement of the pressure plate 8 in the axial direction is allowed, and the pressure plate 8 can approach and separate from the side surfaces of the cam ring 6 and the rotor 5.
[0019]
As shown in FIG. 1, the rotor 5 has a plurality of vane accommodating grooves 10 formed in a radial direction, and a vane 11 having substantially the same width as the thickness of the rotor 5 is accommodated in each accommodating groove 10 so as to be able to advance and retreat. Have been. A coil spring 12 is accommodated in the bottom of each vane accommodating groove 10, and the spring force urges each vane 11 in a protruding direction (toward the outer peripheral side of the rotor 5). A guide projection 13 into which the end of the coil spring 12 is inserted and engaged is projected from the base end of each vane 11, as shown in FIG. The engagement is always maintained.
[0020]
On the other hand, the cam ring 6 has an inner peripheral surface formed into a substantially elliptical cam profile, and the rotor 5 is disposed at a center position of the inner peripheral surface. Here, each vane 11 on the rotor 5 is slidably in close contact with the inner peripheral surface of the cam ring 6, and between the adjacent vanes 11, 11 on the rotor 5 is the rotor 5, the cam ring 6, and the plates 7, 8. A pump chamber is formed in each of the enclosed spaces. The volume of each pump chamber is reduced when the cam profile of the cam ring 6 changes from the major axis to the minor axis, and conversely, the volume increases when the profile changes from the minor to the major. Is done. In the case of this embodiment, since the cam profile on the inner peripheral surface of the cam ring 6 is substantially elliptical, two enlarged regions and reduced regions are respectively arranged at diagonal positions in the cam ring 6. That is, the pump of this embodiment is configured as a so-called pressure balanced vane pump.
[0021]
Strictly speaking, the cam profile on the inner peripheral surface of the cam ring 6 is, as shown in FIG. 1, an enlarged region where the volume of the pump chamber is enlarged (when the rotation direction of the rotor 5 is R, a ₁ , a ₂ ). Area) and a reduced area where the volume is reduced (areas b ₁ and b ₂ when the rotation direction of the rotor 5 is R) is set as a switching area c _{1 to} c ₄ of a perfect circular arc. It is formed over an angle range (at least an angle range equal to or larger than the pitch angle between the adjacent vanes 11, 11). The center of the arc of each of the switching areas c _{1 to} c ₄ is set so as to coincide with the rotation center of the rotor 5, that is, the center of the radial shape formed by the plurality of vane receiving grooves 10. The area of the inner peripheral surface of the cam ring 6 where the volume of the pump chamber is increased and the area where the volume of the pump chamber is increased are formed so as to be symmetrical with each other. Is obtained.
[0022]
At positions facing the areas a ₁ , a ₂ and b ₁ , b ₂ where the volume of the pump chamber of the front side plate 7 expands and contracts, as shown in FIGS. Each is formed. The input / output ports 14 and 15 form a pair, and when one port is used for suction, the other is used for discharge. Also, as shown in FIG. 1, the inlet / outlet ports 14 are connected to a first supply / discharge passage 16, and the inlet / outlet ports 15 are connected to a second supply / discharge passage 17.
[0023]
Further, four back pressure ports 18 are formed in the inner peripheral edge of the front side plate 7 at positions facing the bottom of the vane accommodating groove 10 of the rotor 5. The back pressure port 18 is formed of a circular hole that penetrates the front side plate 7, and has a connection groove 19 (see FIGS. 2 and 5) formed in the rear surface (the surface opposite to the rotor 5) of the plate 7 along the radial direction. 4) to the inlet / outlet port 15 or 16. Therefore, the pressure of the inlet / outlet port 15 or 16 located at substantially the same angular position is introduced into these back pressure ports 18.
[0024]
On the other hand, at positions facing the areas a ₁ , a ₂ and b ₁ , b ₂ where the volume of the pump chamber of the pressure plate 8 expands and contracts, as shown in FIG. 20 is formed, the recess 20 faces in the region _a 1, _{b 1} of the communication hole 21a which penetrates the pressure plate 8 in the axial direction, 21b are formed. 2 and 6, an annular recess 22 is formed on the back side of the pressure plate 8, and a pressure chamber is provided between the back surface of the pressure plate 8 including the annular recess 22 and the bottom in the cover 3. 23 are formed. A check valve 24 is provided in each of the communication holes 21a and 21b to allow only the flow of the hydraulic fluid from inside the cam ring 6 toward the pressure chamber 23. Therefore, regardless of whether the rotor 5 rotates in the forward or reverse direction, the pressure on the higher side of the regions a ₁ and b ₁ , that is, the discharge pressure, is introduced into the pressure chamber 23.
[0025]
Further, four back pressure ports 25 are formed in the annular concave portion 22 of the pressure plate 8 so as to be separated by 90 ° in the circumferential direction. Each of the back pressure ports 25 is formed of a circular conduction hole penetrating the pressure plate 8 in the axial direction, and is opened at a position facing the bottom of the vane accommodating groove 10 in the cam ring 6. These back pressure port 25 is disposed at a position corresponding to the aforementioned cut換Ri region c ₁ to c ₄ in the cam ring 6. Therefore, in the switching areas c _{1 to} c ₄ , the pressure (discharge pressure) of the pressure chamber 23 is constantly introduced into the bottom of the vane accommodating groove 10 through these back pressure ports 25.
[0026]
4 is a concave portion formed at a position corresponding to the back pressure port 25 on the front side plate 7, and 27 in FIG. 5 corresponds to the back pressure port 18 on the pressure plate 8. A recess similarly formed at the location.
[0027]
In the above configuration, when the rotor 5 rotates, for example, in the R direction in FIG. 1, the areas a ₁ and a ₂ and the areas b ₁ and b ₂ in the cam ring 6 become an enlarged area and a reduced area, respectively. The working fluid in the first supply / discharge passage 16 is sucked into the pump chamber through the inlet / outlet port 14, and the working fluid is discharged to the second supply / discharge passage 17 through the inlet / outlet port 15.
[0028]
At this time, each vane 11 on the rotor 5 is pressed against the inner circumferential surface of the cam ring 6 by the centrifugal force accompanying the rotation of the rotor 5 and the force of the coil spring 12. In addition, the pressure of the hydraulic fluid introduced into the bottom of the vane accommodating groove 10 through the back pressure ports 18 and 25 acts.
[0029]
That is, since the back pressure port 18 formed in the front side plate 7 is electrically connected to the inlet / outlet port 14 or 15 located at substantially the same angular position through the connection groove 19, the back pressure port 18 extends in the enlarged areas a ₁ and a ₂ in the cam ring 6. The suction pressure of the inlet / outlet port 14 is introduced to the back pressure port 18 located, and the discharge pressure of the inlet / outlet port 15 is introduced to the back pressure port 18 located in the reduced areas b ₁ , b ₂ . Therefore, the suction pressure and the discharge pressure act on the bases of the vanes 11 in the enlarged areas a ₁ and a ₂ and the reduced areas b ₁ and b ₂ , respectively.
[0030]
Further, since the back pressure port 25 formed in the pressure plate 8 is electrically connected to the pressure chamber 23, the discharge pressure of the reduction area b ₁ by opening the check valve 24 of the communication hole 21b is introduced into the pressure chamber 23, The discharge pressure acts on the base of the vane 11 located in the switching areas c _{1 to} c ₄ in the cam ring 6. For this reason, in the switching areas c _{1 to} c ₄ , the leading end of the vane 11 is always reliably pressed against the inner surface of the cam ring 6, and the leading end of the vane 11 is separated from the cam ring 6 from the discharge side to the suction side. Hydraulic fluid is prevented from leaking.
[0031]
On the other hand, when the rotor 5 rotates in the R 'direction of FIG. 1, a ₁ and a ₂ in the cam ring 6 are switched to the enlarged region, and b ₁ and b ₂ are switched to the reduced region. The discharge of the working fluid is performed from 15 to 14. At this time, the discharge pressure and the suction pressure act on the bases of the vanes 11 in the reduced areas a ₁ and a ₂ and the enlarged areas b ₁ and b ₂ , respectively, and the vanes located in the switching areas c _{1 to} c _4. The discharge pressure 23 of the pressure chamber 23 acts on the base of 11. The pressure of the reduced area a ₁ through the communication hole 21a to the pressure chamber 23 at this time is introduced. Therefore, also in this case, the distal end of the vane 11 can be always in close contact with the inner peripheral surface of the cam ring 6.
[0032]
This vane pump can realize bidirectional operation as described above. However, the cam profile of the cam ring 6 in the switching areas c _{1 to} c ₄ has a perfect circular arc centered on the rotation center of the rotor 5. In the switching areas c _{1 to} c ₄ , the vanes 11 do not move forward and backward, so that there is no problem that the pressure at the bottom of the vane housing groove 10 increases. Therefore, in the case of this vane pump, the sliding resistance of the vane 11 does not increase abruptly in the switching areas c _{1 to} c ₄ , so that the pump can be operated smoothly and the vane 11 can be quickly worn. It can be prevented before it happens.
[0033]
Further, in the bidirectional vane pump of this embodiment, a pressure chamber 23 is formed on the back side of the pressure plate 8, and the pressure chamber 23 and the expansion / contraction regions a ₁ and b ₁ in the cam ring 6 communicate with the communication holes 21 a respectively. , 21b and a check valve 24 is interposed in these communication holes 21a, 21b, so that the pressure plate 8 is brought into close contact with the side surface of the rotor 5 with the discharge pressure regardless of the rotation direction of the rotor 5. be able to. Therefore, no matter which way the rotor 5 rotates, leakage of the hydraulic fluid from the side of the rotor 5 can be effectively prevented.
[0034]
Further, the communication passage for introducing the discharge pressure to the back pressure port 25 can be formed on the front side plate 7 side, but if it is formed on the pressure plate 8 side as in the vane pump of this embodiment. Thus, the passage of the pressure chamber 23 can be shared as it is, and the passage structure can be greatly simplified. In other words, in the case of this embodiment, if a conduction hole is formed in the pressure plate 8 to communicate the bottom side of the vane accommodating groove 10 with the pressure chamber 23 and the hole is used as the back pressure port 25, it is necessary to form a complicated communication passage. There is no.
[0035]
Furthermore, since the vane pump of this embodiment is a so-called pressure-balanced vane pump, there is an advantage that the pressure balance during operation of the pump is good and noise and pulsation are less generated.
[0036]
Next, a second embodiment shown in FIG. 7 will be described.
[0037]
The bidirectional vane pump according to this embodiment has a basic configuration substantially the same as that of the first embodiment, except that a discharge pressure is always introduced to the bottom of the vane accommodating groove. It differs from that of the first embodiment.
[0038]
That is, in the first embodiment, four independent back pressure ports 18 are formed in the front side plate 7. However, in the vane pump of the second embodiment, the front back plate is not provided with the independent back pressure port. An annular groove 30 is formed in the inner peripheral edge of the side plate 107, and the discharge pressure is always introduced into all the vane accommodation grooves via the annular groove 30. A back pressure port similar to that of the first embodiment is formed on the pressure plate side, and the discharge pressure is introduced into the annular groove 30 on the front side plate 107 side across any vane accommodation groove.
[0039]
In the case of this embodiment, substantially the same effects as in the first embodiment can be obtained, but there is an additional advantage that the passage structure on the front plate 107 side can be simplified and the manufacturing cost can be reduced.
[0040]
Next, a third embodiment shown in FIGS. 8 and 9 will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and duplicate description will be omitted.
[0041]
The bidirectional vane pump of this embodiment is different from the first embodiment in that the discharge pressure of the pump chamber is not introduced into the pressure chamber, but the discharge pressure at the bottom of the vane housing groove is introduced into the pressure chamber. It is different from the form.
[0042]
That is, the bottom of the vane accommodating groove performs a pumping operation in accordance with the reciprocating operation of the vane. In the case of the vane pump of this embodiment, the area of the inner peripheral edge of the pressure plate 208 where the volume of the vane accommodating groove is increased. The communication holes 221a and 221b that communicate with the pressure chamber 23 are formed in the reduced area, and the check valve 24 is interposed in each of the communication holes 221a and 221b.
[0043]
In the case of this embodiment, although the pressure introduced into the pressure chamber 23 is the discharge pressure at the bottom of the vane groove, the discharge pressure can be constantly applied to the switching region in the cam ring as in the first embodiment. .
[0044]
Although the bidirectional vane pump has been described above, the bidirectional vane motor is connected to the hydraulic circuit having the supply / discharge switching mechanism by connecting the first and second supply / discharge passages with the same structure. Can be used as In this case, the pump chamber functions as a variable volume chamber that rotates the rotor in a direction to expand the volume by receiving the supply pressure, and the supply pressure is introduced through the check valve to the back pressure port located in the switching area. The Rukoto.
[0045]
Next, inventions other than those described in the claims that can be understood from the above embodiments will be described below together with their operational effects.
[0046]
(B) It is assumed that the two reduced regions in which the volume of the variable volume chamber is reduced and the two enlarged regions in which the volume of the variable volume chamber is expanded are pressure-balanced motors that are respectively arranged at diagonal positions in the cam ring. The bidirectional vane motor according to claim 4, wherein:
[0047]
In this case, the motor operation is balanced, and the quietness is enhanced.
[0048]
(B) The one side wall member is disposed so as to be able to approach and separate from the rotor in the axial direction, and a pressure force in the rotor direction is applied to the side wall member at a position facing the surface of the side wall member opposite to the rotor. A pressure chamber is formed in the side wall member, and a communication hole and a check valve for introducing the supply pressure into the pressure chamber are provided in the side wall member, and the pressure in the pressure chamber is introduced to the bottom of the vane receiving groove in the switching area. 5. The bidirectional vane motor according to claim 4, wherein a communication hole is provided, a communication path is formed by the communication hole and the pressure chamber, and a back pressure port is formed by the communication hole. 6.
[0049]
In this case, since the pressure chamber and the communication hole for introducing the supply pressure into the pressure chamber are shared with the communication path, the entire passage structure can be greatly simplified.
[Brief description of the drawings]
FIG. 1 is a sectional view taken along the line BB of FIG. 2 showing a first embodiment of the present invention;
FIG. 2 is an exemplary sectional view of the same embodiment taken along line AA of FIG. 1;
FIG. 3 is a perspective view showing the same embodiment.
FIG. 4 is a front view of one side wall member (front side plate) showing the embodiment.
FIG. 5 is a front view of the other side wall member (pressure plate) showing the embodiment.
FIG. 6 is a rear view of the other side wall member (pressure plate) showing the embodiment.
FIG. 7 is a front view of the other side wall member (pressure plate) showing the second embodiment of the present invention.
FIG. 8 is a front view of the other side wall member (pressure plate) showing the third embodiment of the present invention.
FIG. 9 is a sectional view of the same embodiment, taken along line CC in FIG. 8;
[Explanation of symbols]
4 Drive shaft 5 Rotor 6 Cam ring 7, 107 Front side plate (side wall member)
8,208 ... pressure plate (side wall member)
10 vane receiving groove 11 vanes 14, 15 inlet / outlet ports 18, 25 back pressure ports 21a, 21b, 221a, 221b communication hole (communication passage)
23 ... Pressure chamber (communication passage)
24… Check valve

Claims (4)

A rotor that is rotationally driven by a drive shaft;
A plurality of vanes attached to the rotor so as to be able to advance and retreat radially;
A cam ring that rotatably accommodates the rotor on the inner peripheral side, guides the advance / retreat operation of each vane along a cam profile of the inner peripheral surface, and increases or decreases the volume of the pump chamber between adjacent vanes;
A non-rotating side wall member disposed on a side of the cam ring;
At least one pair of inlet / outlet ports formed at positions facing a region where the volume of the pump chamber is enlarged and a region where the volume of the pump chamber is reduced,
A back pressure port formed at a position of the side wall member facing the bottom of the vane accommodating groove of the rotor and for applying a pressure of hydraulic fluid to a base of the vane;
A communication path for introducing the discharge pressure at the bottom of the pump chamber or the vane housing groove to a back pressure port located in a switching area between a region where the volume of the pump chamber is reduced and a region where the volume is reduced via a check valve; ,
A bidirectional vane pump in which suction and discharge of the paired input / output ports are switched according to a rotation direction of a rotor,
A bidirectional vane pump, wherein a cam profile of a cam ring located in the switching area is formed as a perfect circular arc having a center at a center of a radial shape formed by a plurality of vane receiving grooves. The pressure-balance type pump wherein two reduced areas in which the volume of the pump chamber is reduced and two expanded areas in which the volume of the pump chamber is expanded are respectively disposed at diagonal positions in the cam ring. 2. The bidirectional vane pump according to 1. The one side wall member is arranged so as to be able to approach and separate in the axial direction with respect to the rotor, and a pressure for applying a pressure contact force in the rotor direction to the side wall member at a position facing the surface of the side wall member opposite to the rotor. A communication chamber and a communication hole for introducing discharge pressure to the pressure chamber and a check valve are provided in the side wall member, and the pressure of the pressure chamber is introduced to the bottom of the vane accommodating groove in the switching area. 3. The bidirectional vane pump according to claim 1, wherein a hole is provided, a communication path is formed by the communication hole and the pressure chamber, and a back pressure port is formed by the communication hole. A rotor connected to the output shaft;
A plurality of vanes attached to the rotor so as to be able to advance and retreat radially;
A cam ring that rotatably accommodates the rotor on the inner peripheral side, guides the advance / retreat operation of each vane along a cam profile of the inner peripheral surface, and forms a variable volume chamber between adjacent vanes;
A non-rotating side wall member disposed on a side of the cam ring;
Of the side wall member, at least a pair of input / output ports formed at positions facing the area where the volume of the variable volume chamber expands and the area where the volume decreases.
A back pressure port formed at a position of the side wall member facing the bottom of the vane accommodating groove of the rotor and for applying a pressure of hydraulic fluid to a base of the vane;
A communication path for introducing a supply pressure through a check valve to a back pressure port located in a switching region between a region in which the volume of the variable volume chamber is reduced and a region in which the volume is expanded,
A bidirectional vane motor in which the rotation direction of the rotor is switched by switching between supply and discharge of the pair of input / output ports,
A bidirectional vane motor, wherein a cam profile of a cam ring located in the switching area is formed as a perfect circular arc having a center at a center of a radial shape formed by a plurality of vane receiving grooves.

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