JP5762202B2 - Variable displacement vane pump - Google Patents

Description

  The present invention relates to a variable displacement vane pump used in a working fluid utilizing device such as a power steering device for reducing the steering force of an automobile, for example.

  Conventionally, as a well-known technique related to this type of variable displacement vane pump, for example, in order to prevent hydraulic oil pulsation in a wide eccentric region of the cam ring, the inner diameter of the cam ring, between the suction section and the discharge section in the pump chamber. "Variable capacity pump" with a negative gradient curve starting from the end of the suction port and connecting the negative gradient curve and the perfect circle curve with a higher order curve. Patent Document 1).

JP 2002-115673 A

  In general, in variable displacement vane pumps, pressure pulsation occurs due to vane separation in which the vane separates from the inner circumferential surface of the cam ring in a fixed displacement region corresponding to a low pump rotation speed region where the discharge amount per rotation is constant. In the variable capacity range corresponding to the high pump speed range where the discharge rate per revolution decreases as the pump speed increases or the pump speed increases, the pressure unbalance occurs and the fixed displacement vane pump Since vibration is likely to be larger than in the case and noise is generated due to such pressure pulsation and vibration, it is a technical problem to suppress such noise.

  In the variable displacement vane pump according to Patent Document 1 described above, in order to suppress noise due to vane separation, the discharge from the terminal end of the suction port on the inner peripheral surface of the cam ring at the time of maximum eccentricity when the eccentric amount of the cam ring is the largest with respect to the rotor. The area between the outlet end and the area from the end of the discharge port to the inlet end is formed so that the distance from the rotation center of the rotor gradually decreases as the rotor rotates. This prevents the vane from separating and suppresses the generation of noise.

  However, if the inner peripheral surface of the cam ring has such a shape, the volume compression amount of the pump chamber increases in the variable capacity region, and the peak pressure increases. Therefore, there is a problem that noise due to vibration is likely to occur.

  In short, the variable displacement vane pump according to Patent Document 1 suppresses vane separation in the fixed displacement region, and even if noise generation due to pressure pulsation can be prevented, the pressure peak of the pump chamber in the variable displacement region is suppressed. Therefore, it is difficult to prevent the generation of noise due to vibration.

  The present invention has been made to solve such problems, and its technical problem is to suppress the vane separation in the fixed capacity region and the pressure peak of the pump chamber in the variable capacity region. It is an object of the present invention to provide a variable displacement vane pump having a structure capable of sufficiently preventing noise generation due to vibration.

In order to solve the above technical problem, a first means of the present invention transmits a steering operation of a steering wheel to a steered wheel and generates a steering assist force by a hydraulic pressure of the hydraulic fluid. A variable displacement vane pump for supplying a pump housing, a pump housing having a pump element housing portion, a drive shaft pivotally supported by the pump housing, a rotary shaft provided in the pump housing and driven to rotate by the drive shaft, A rotor having a plurality of slots in the circumferential direction, a plurality of vanes provided so as to be able to protrude and retract with respect to the plurality of slots, and a ring formed so as to be movable with respect to the pump element housing portion A cam ring that forms a plurality of pump chambers with a plurality of vanes, and a cam housing that controls the eccentric amount of the cam ring relative to the rotor. And a pump housing is opened to a region where the volume of the plurality of pump chambers increases as the rotor rotates and a region where the volumes of the plurality of pump chambers decrease. and a discharge port, the inner peripheral surface of the cam ring, the midpoint of the eccentric amount of the cam ring to the rotor is the largest maximum eccentricity state end of put that the discharge port in the rotational direction of the rotor start end of the suction port from Te region odor until beginning of the suction port, the distance between the rotation center of the rotor is formed so as to gradually become shorter in accordance with the rotation of the rotor, and the eccentric amount of the cam ring relative to the rotor smallest at the minimum end of the inlet eccentrically and an intermediate point between the starting end of the discharge opening to at least part of the region between the up beginning of the discharge ports during rotation of the rotor The distance between which is characterized in that formed to be substantially constant or gradually lengthened in accordance with the rotation of the rotor.

The second means is the first means, in which the drive shaft is rotationally driven by the engine of the vehicle, and the inner peripheral surface of the cam ring is intermediate between the end portion of the suction port and the start end portion of the discharge port in the running state of the vehicle. at at least part of the region between the up beginning of the discharge port from the point, that the distance between the rotation center of the rotor is formed to be substantially constant or gradually lengthened in accordance with the rotation of the rotor Features.

The third means is the first means, wherein the drive shaft is rotationally driven by the engine of the vehicle, and the inner peripheral surface of the cam ring is connected to the end portion of the suction port in a state where the engine speed is 1500 rpm or more. from an intermediate point between the starting end of the discharge port at at least part of the region between the up beginning of the discharge port, the distance between the center of rotation of the rotor substantially constant or gradually lengthened in accordance with the rotation of the rotor It was formed as follows.

According to a fourth means, in the first means, the inner peripheral surface of the cam ring is a region between the intermediate point between the end portion of the discharge port and the start end portion of the suction port in the maximum eccentric state and the start end portion of the suction port. smell Te, the front and rear region connected to the region is formed to be connected by a high-order curve, and a minimum eccentric state from an intermediate point between the starting end of the end portion of the suction port and the discharge port of the discharge port at the realm of until beginning, characterized in that the front and rear region connected to the region is formed so as to be connected by a high-order curve.

The fifth means is the first means, wherein the inner peripheral surface of the cam ring is a region between the intermediate point between the end portion of the suction port and the start end portion of the discharge port and the start end portion of the discharge port in a minimum eccentric state. at at least part of the distance between the rotation center of the rotor, characterized in that it is formed so as to gradually increase along with the rotation of the rotor.

  The sixth means is the first means, wherein the cam ring swings or rolls in a state of being supported by a support surface provided on the discharge port side of the inner peripheral surface of the pump element accommodating portion. The amount of eccentricity is controlled.

The seventh means is the sixth means wherein the center of the inner diameter of the cam ring is in a no-load state in which the pressure difference between the suction side pressure and the discharge side pressure does not act on the drive shaft, the rotor, and the cam ring. in the well as located on the inlet side of the rotor center, the relative position of the no-load state the drive shaft by the differential pressure acts against state depot over preparative reference line elastically deformed to the inlet side The cam ring is supported by rolling on a support surface provided on the discharge port side of the inner peripheral surface of the pump element housing portion, and the cam surface is provided with a cam ring. The center of the inner diameter of the cam ring is formed so as to gradually move away from the port reference line toward the discharge port as it rolls from the maximum eccentric state to the minimum eccentric state.

The eighth means is characterized in that in the first means, an odd number of the plurality of slots and the plurality of vanes in the rotor are provided .

The ninth means is a variable displacement vane pump for transmitting the steering operation of the steering wheel to the steered wheels and supplying the hydraulic fluid to the vehicle steering device that generates the steering assist force by the hydraulic pressure of the hydraulic fluid. A pump housing having a pump element accommodating portion, a drive shaft supported by the pump housing, a rotor provided in the pump housing and driven to rotate by the drive shaft, and having a plurality of slots in the circumferential direction; A plurality of vanes provided in a plurality of slots so as to be movable in and out, and a cam ring formed in an annular shape so as to be movable with respect to the pump element housing portion, and forming a plurality of pump chambers together with the rotor and the plurality of vanes on the inner peripheral side And a cam ring control mechanism that is provided in the pump housing and controls the amount of eccentricity of the cam ring with respect to the rotor. Jing has a suction port opened in a region where the volumes of a plurality of pump chambers increase as the rotor rotates, and a discharge port opened in a region where the volumes of the plurality of pump chambers decrease. The inner peripheral surface is a distance from the rotation center of the rotor in the region between the terminal end of the discharge port and the start end of the suction port in the rotation direction of the rotor in the maximum eccentric state where the cam ring is eccentric most with respect to the rotor. Is formed so as to be gradually shortened with the rotation of the rotor, and between the terminal end of the suction port and the start end of the discharge port in the minimum eccentric state where the eccentric amount of the cam ring with respect to the rotor is the smallest. In at least a part of the region, the distance from the rotation center of the rotor is formed to be substantially constant or gradually increased with the rotation of the rotor .

A tenth means is the ninth means, wherein the drive shaft is rotationally driven by the engine of the vehicle, and the inner peripheral surface of the cam ring is between the terminal end of the suction port and the start end of the discharge port in the running state of the vehicle. In at least a part of the region, the distance from the rotation center of the rotor is formed to be substantially constant or gradually longer as the rotor rotates .

The eleventh means is the ninth means, wherein the drive shaft is rotationally driven by the engine of the vehicle, and the inner peripheral surface of the cam ring extends from the end of the intake port in a state where the engine speed is 1500 revolutions per minute or more. The distance from the rotation center of the rotor is formed to be substantially constant or gradually longer with the rotation of the rotor in at least a part of the region up to the start end of the discharge port .

A twelfth means is the ninth means wherein the cam ring swings or rolls while being supported by a support surface provided on the discharge port side of the inner peripheral surface of the pump element accommodating portion, The amount of eccentricity is controlled .

Means 13, in the first and second means, the cam ring, by swinging or tumbling in a state of being supported on the support surface provided on the discharge port side of the inner peripheral surface of the pump element housing section, the rotor The amount of eccentricity is controlled .

A fourteenth means is a variable displacement vane pump for supplying a hydraulic fluid to a vehicle steering device that transmits a steering operation of a steering wheel to a steered wheel and generates a steering assist force by a hydraulic pressure of the hydraulic fluid. A pump housing having a pump element accommodating portion, a drive shaft supported by the pump housing, a rotor provided in the pump housing and driven to rotate by the drive shaft, and having a plurality of slots in the circumferential direction; A plurality of vanes provided in a plurality of slots so as to be movable in and out, and a cam ring formed in an annular shape so as to be movable with respect to the pump element housing portion, and forming a plurality of pump chambers together with the rotor and the plurality of vanes on the inner peripheral side And a cam ring control mechanism that is provided in the pump housing and controls the amount of eccentricity of the cam ring with respect to the rotor. Uzing has a suction port opened in a region where the volumes of a plurality of pump chambers increase as the rotor rotates, and a discharge port opened in a region where the volumes of the plurality of pump chambers decrease. The inner peripheral surface of the cam ring is compared with a no-load state in which the differential pressure between the suction port side pressure and the discharge port side pressure acts on the drive shaft, rotor, and the cam ring. From the terminal end portion of the discharge port in the rotational direction of the rotor in the maximum eccentric state where the eccentric amount of the cam ring with respect to the rotor is the largest in the state of moving relative to the discharge port side with respect to the suction port. The cam ring with respect to the rotor is formed such that the distance from the rotation center of the rotor gradually decreases with the rotation of the rotor in the region between the start end of the suction port. In at least a part of the region between the end portion of the suction port and the start end portion of the discharge port in the minimum eccentric state where the amount of eccentricity is the smallest, the distance from the rotation center of the rotor is substantially reduced with the rotation of the rotor. It is characterized by being formed to be constant or gradually longer .

According to a fifteenth aspect, in the fourteenth aspect, the drive shaft is rotationally driven by the engine of the vehicle, and the inner peripheral surface of the cam ring is between the terminal end of the suction port and the start end of the discharge port in the running state of the vehicle. In at least a part of the region, the distance from the rotation center of the rotor is formed so as to be substantially constant or gradually increased with the rotation of the rotor .

A sixteenth means is the fourteenth means according to the fourteenth means, wherein the drive shaft is rotationally driven by the engine of the vehicle, and the inner peripheral surface of the cam ring extends from the end portion of the suction port in a state where the engine speed is 1500 rpm or more. The distance from the rotation center of the rotor is formed to be substantially constant or gradually longer with the rotation of the rotor in at least a part of the region up to the start end of the discharge port .

Means 17, in the means of the first 4, the cam ring, by swinging or tumbling in a state of being supported on the support surface provided on the discharge port side of the inner peripheral surface of the pump element housing section, the rotor The amount of eccentricity is controlled .

Means 18, in the unit of the first 7, the inner diameter center of the cam ring, a drive shaft, a rotor, and unloaded the differential pressure between the pressure of the pressure and the discharge port side of the suction port side does not act on the cam ring In this state, it is located on the suction port side with respect to the port reference line connecting the intermediate point between the end portion of the suction port and the start end portion of the discharge port and the rotor center, and the driving is performed by the differential pressure acting. The cam ring is provided so that the relative position to the port reference line is located closer to the discharge port than the relative position in the no-load state with the shaft elastically deformed toward the suction port. The support surface is rolled and supported by a support surface provided on the discharge port side of the peripheral surface, and as the cam ring rolls from the maximum eccentric state to the minimum eccentric state, the inner diameter center of the cam ring becomes the port reference line. Gradually It is characterized by being formed so as to be separated from each other.

  According to the variable displacement vane pump of the present invention, the shape of the inner peripheral surface of the cam ring is devised so that both the vane separation in the fixed displacement region and the pressure peak of the pump chamber in the variable displacement region can be suppressed. Therefore, it is possible to sufficiently prevent the occurrence of noise due to pressure pulsation and vibration regardless of whether it is a fixed capacity region or a variable capacity region.

It is the side view which showed the basic structure of the variable displacement type vane pump which concerns on Example 1 of this invention in the cross section along the extending direction of the drive shaft. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1 in a maximum eccentric state in which the eccentric amount of the cam ring with respect to the rotor is the largest in the variable displacement vane pump according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1 in the minimum eccentric state where the eccentric amount of the cam ring with respect to the rotor is the smallest in the variable displacement vane pump according to the first embodiment of the present invention. FIG. 3 is a schematic diagram showing a relative positional relationship between the inner peripheral surface of the cam ring and the suction port and the discharge port of the pressure plate in the maximum eccentric state described in FIG. 2. FIG. 4 is a schematic diagram showing a relative positional relationship between the inner peripheral surface of the cam ring and the suction port and the discharge port of the pressure plate in the minimum eccentric state described in FIG. 3. It is a characteristic diagram showing the distance between the rotation center of the rotor and the inner peripheral surface of the cam ring on the first seal section side in the variable displacement vane pump according to the first embodiment of the present invention, (a) in the maximum eccentric state (B) is a characteristic diagram of the dynamic radius with respect to the angle in the minimum eccentric state, and (c) is a characteristic diagram of the volume with respect to the central angle of the vane chamber in the minimum eccentric state. It is a characteristic diagram showing the distance between the rotation center of the rotor and the inner peripheral surface of the cam ring on the second seal section side in the variable displacement vane pump according to the first embodiment of the present invention, (a) in the maximum eccentric state (B) is a characteristic diagram of the dynamic radius with respect to the angle in the minimum eccentric state, and (c) is a characteristic diagram of the volume with respect to the central angle of the vane chamber in the minimum eccentric state. It is the schematic diagram which fractured | ruptured and showed the local part in order to demonstrate the mechanism of the vane separation | spacing which generate | occur | produces in the structure before improvement in the variable displacement vane pump which concerns on Example 1 of this invention. It is a characteristic line figure of pressure to an angle shown in order to explain a pressure peak of a vane room which occurs in a structure before improvement in a variable capacity type vane pump concerning Example 1 of the present invention. It is the schematic diagram which showed the relative positional relationship of a rotor, a cam ring, a discharge port, and a suction port with respect to the support surface provided in the adapter in the variable displacement vane pump which concerns on Example 5 of this invention, (a) is the maximum eccentric state (B) is a schematic diagram in the minimum eccentric state.

  Hereinafter, the variable displacement vane pump of the present invention will be described in detail with reference to the drawings, with some examples.

  FIG. 1 is a side view showing a basic structure of a variable displacement vane pump 1 according to a first embodiment of the present invention in a cross section along an extending direction of a shaft 13 that is a drive shaft. FIG. 2 is a cross-sectional view along the line AA in FIG. 1 in the maximum eccentric state in which the eccentric amount of the cam ring 15 with respect to the rotor 11 in the variable displacement vane pump 1 is the largest. FIG. 3 is a cross-sectional view along the AA line direction in FIG. 1 in the minimum eccentric state where the eccentric amount of the cam ring 15 with respect to the rotor 11 in the variable displacement vane pump 1 is the smallest. 4 is a schematic diagram showing a relative positional relationship between the inner peripheral surface of the cam ring 15 and the suction port 22 and the discharge port 21 of the pressure plate 27 in the maximum eccentric state described with reference to FIG. FIG. 5 is a schematic diagram showing a relative positional relationship between the inner peripheral surface of the cam ring 15 and the suction port 22 and the discharge port 21 of the pressure plate 27 in the minimum eccentric state described with reference to FIG. FIG. 1 corresponds to a cross-sectional view in the direction of the line BB in FIG. Moreover, the dotted line shown in FIG.4 and FIG.5 is a thing when the internal peripheral surface of the cam ring 15 is a perfect circle in a perimeter.

  Referring to the drawings, the variable displacement vane pump 1 has a pump component including a rotor 11, a vane 14, a cam ring 15, an adapter 12, a pressure plate 27, and a control valve 30 incorporated therein. The concave front body 10 and the rear cover 19 are combined to form a main body structure as a pump housing.

  Among these, the rotor 11 is connected to a shaft 13 which is a driving shaft for transmitting a driving force from the outside, and the shaft 13 is supported by the front body 10 via a bearing 28. The rotor 11 is provided with a plurality of slots 29. The number of slots 29 is, for example, an odd number, and vanes 14 are inserted in the slots 29. The vanes 14 can move freely in the radial direction. A vane bottom 31 is provided at the inner end of each slot 29. The rotor 11 is rotationally driven by the shaft 13.

  An adapter 12 is fitted in the recess of the front body 10, and a cam ring 15 supported so as to be able to swing inside the adapter 12 around the support pin 16 is arranged with the center of the inner diameter being eccentric from the rotation center of the rotor 11. Yes. As shown in FIG. 2, the cam ring 15 and the adapter 12 form a first fluid pressure chamber 34 on the left side of the cam ring 15 and a second fluid pressure chamber 35 on the right side. The cam ring 15 is urged by the compression coil spring 17 in a direction in which the pump capacity of the vane chamber 18 is maximized.

  A space between the rotor 11 and the cam ring 15 is divided by the vanes 14 to form a plurality of vane chambers 18. Each vane chamber 18 is connected to a discharge port 21 serving as a discharge port in a region where the volume is reduced due to counterclockwise rotation in FIG. 2, and connected to a suction port 22 serving as a suction port in a region where the volume is increased. Has been. A pressure plate 27 is fitted between the rotor 11, the cam ring 15, the vane 14, and the adapter 12 and the front body 10.

  The control valve 30 includes a valve hole 30a formed in the front body 10, a spool 30b slidably disposed in the valve hole 30a, and a spring 30c. A spring chamber 36 is provided on one end side of the control valve 30, and a spring 30 c is installed in the spring chamber 36. The control valve 30 is operated by the relationship between the force due to the pressure of the control valve high pressure chamber 37 on one end side, the force due to the pressure of the spring chamber 36 on the other end side, and the force due to the biasing force of the spring 30c. When the rightward force in FIG. 2 due to the pressure difference between the control valve high pressure chamber 37 and the spring chamber 36 is greater than the leftward force due to the spring 30c and the spool 30b moves to the right, the control valve high pressure chamber 37 is accordingly moved. And a passage between the passage 33 connected to the first fluid pressure chamber and the passage between the passage 33 and the tank side (not shown) become narrower.

  Incidentally, the control valve 30, the first fluid pressure chamber 34, the second fluid pressure chamber 35, and the like provided in the front body 10 cooperate with the fluid pressure during operation to reduce the eccentric amount of the cam ring 15 with respect to the rotor 11. It functions as a cam ring control mechanism for controlling.

  Hereinafter, the shape of the inner peripheral surface of the cam ring 15 will be described. When the pump as shown in FIG. 2 is not operated, the cam ring 15 is in the maximum eccentric state where the center of the inner diameter is the most eccentric from the rotation center Or of the rotor 11 as shown in FIG. Further, the cam ring 15 shown in FIG. 3 operates in a direction in which the center of the inner diameter becomes smaller in the amount of eccentricity from the rotation center Or of the rotor 11 by the operation described later, and as shown in FIG. The minimum eccentric state where the amount of eccentricity is minimized.

  Here, the distance between the rotation center Or of the rotor 11 and the inner peripheral surface of the cam ring 15 is called a moving radius, and the vane 14 is tanked from the end of the suction port 22 to the start of the discharge port 21 in the rotation direction of the rotor 11. This is a section in which the pressure vane chamber 18 and the discharge pressure vane chamber 18 are sealed. This section is referred to as a first seal section, and a similar section from the terminal end of the discharge port 21 to the start end of the suction port 22. Is called the second seal section.

  FIG. 6 is a characteristic diagram showing the distance between the rotation center Or of the rotor 11 and the inner peripheral surface of the cam ring 15 on the first seal section side in the variable displacement vane pump 1, and FIG. 6 (a) shows the maximum eccentricity. (B) is a characteristic diagram of the dynamic radius with respect to the angle in the minimum eccentric state, and (c) is a characteristic diagram of the vane chamber 18 in the minimum eccentric state. It is a volume characteristic diagram. FIG. 7 is a characteristic diagram showing the distance between the rotation center Or of the rotor 11 and the inner peripheral surface of the cam ring 15 on the second seal section side in the variable displacement vane pump 1, and FIG. 7 (a) shows the maximum eccentric state. (B) is a characteristic diagram of the dynamic radius with respect to the angle in the minimum eccentric state, and (c) is a volume with respect to the central angle of the vane chamber 18 in the minimum eccentric state. FIG. The dotted lines in the characteristic diagrams in FIGS. 6A to 6C and FIGS. 7A to 7C are for the case where the inner circumferential surface of the cam ring 15 is a perfect circle on the entire circumference.

  More specifically, the relationship between the angle and the moving radius in the maximum eccentric state of FIG. 4 is shown as a characteristic diagram of the first seal section of FIG. 6A, and FIG. The characteristic diagram which shows the relationship between the angle and dynamic radius in the maximum eccentric state about 2 seal | sticker area is shown.

  Referring to FIGS. 6A and 7A, the inner peripheral surface of the cam ring 15 according to the first embodiment is at the intermediate point (suction port) from the beginning of the first seal section (the end portion of the suction port 22). 22 (intermediate point between the end portion of 22 and the start end portion of the discharge port 21), and the end point (intermediate point between the end portion of the discharge port 21 and the start end portion of the suction port 22) of the second seal section About the area | region to the suction port 22, the moving radius is formed so that it may become short gradually.

  Further, when the cam ring 15 moves to the minimum eccentric state shown in FIG. 5, the relationship between the angle and the moving radius is shown as shown in the characteristic diagrams of the minimum eccentric state in FIGS. 6 (b) and 7 (b). Change. Therefore, referring to FIGS. 6B and 7B, the inner peripheral surface of the cam ring 15 according to the first embodiment is an intermediate point between the first seal section (the end portion of the suction port 22 and the discharge port 21). At least part of the region from the start point (intermediate point to the start end) to the end (start end portion of the discharge port 21) and from the start of the second seal section (end portion of the discharge port 21) to the intermediate point (end of the discharge port 21) And at least part of the region up to the intermediate point between the first portion and the discharge port 21, the moving radius is formed to be substantially constant or gradually longer as the rotor 11 rotates.

  Furthermore, according to the structure, referring to FIG. 6C, in the minimum eccentric state related to the first seal section, the first confinement section (the pressure in the vane chamber 18 changes from the tank pressure to the discharge pressure). In operation, as will be described in detail later, in the interval from the time when the rear vane 14 of the vane chamber 18 passes the terminal end of the discharge port 21 to the time when the front vane 14 reaches the start end of the suction port 22), The volume can be reduced within a narrow range of the central angle of the vane chamber 18. Further, referring to FIG. 7C, in the minimum eccentric state related to the second seal section, a second confinement section in which the pressure in the vane chamber 18 changes from the discharge pressure to the tank pressure (in a later sentence in terms of operation). As will be described in detail, in the interval from the time when the vane 14 behind the vane chamber 18 passes the end of the discharge port 21 to the time when the front vane 14 reaches the start end of the suction port 22, A small gradient in which the volume changes from increasing to decreasing in a narrow range of angles is shown.

  By the way, the kinetic radius is not independent in the maximum eccentricity state and the minimum eccentricity state, but for the region from the middle point of the first seal section to the end thereof, and the region from the beginning of the second seal section to the middle point thereof, If the amount of decrease in the dynamic radius is not excessive in the maximum eccentric state, the shape can be made substantially constant or gradually longer in the minimum eccentric state.

  Next, the connection of the flow path between each chamber is demonstrated. The suction port 22 is connected to a tank (not shown). The discharge port 21 is introduced into the pressure chamber 26 on the front body 10 side through a passage (not shown) provided in the pressure plate 27. The pressure chamber 26 is connected to a discharge side pipe 32 connected to a device such as a power cylinder (not shown) via the metering orifice 23, and is further connected to the spring chamber 36 from the discharge side pipe upstream portion 32a. The pressure chamber 26 is connected to the control valve high pressure chamber 37 via the damper orifice 20. Further, the pressure chamber 26 is also connected to the vane bottom 31 by a passage (not shown).

  The operation of the variable displacement vane pump 1 will be described below. When a rotational driving force is input from the shaft 13, the vane 14 rotates with the rotor 11 while being pressed against the cam ring 15 by the centrifugal force and the pressure of the vane bottom 31, and the volume of the vane chamber 18 increases or decreases. In the section in which the volume increases, the pressure in the vane chamber 18 decreases and the working fluid is sucked from the suction port 22. This section may be called an inhalation section. The suctioned working fluid is pressurized as the volume of the vane chamber 18 decreases in the first confinement section shown in FIG. 6C that is not connected to the tank or the pressure chamber 26.

  The pressurized working fluid is guided from the discharge port 21 to the pressure chamber 26 as the volume of the vane chamber 18 decreases. This section may be called a discharge section. Further, the pressure in the vane chamber 18 decreases through the second confinement section shown in FIG. 7C which is not connected to the tank or the pressure chamber 26, and the process proceeds to the suction process again.

  Here, when the pump speed is low, the cam ring 15 is urged by the compression coil spring 17 in the direction in which the pump volume is maximized. At this time, the eccentric amount between the center of the inner diameter of the cam ring 15 and the rotation center Or of the rotor 11 is increased. Is the largest. In this maximum eccentric state, even if the rotation speed changes, the discharge amount per pump rotation is constant, and such a low pump rotation speed region where the discharge amount per rotation is constant is called a fixed capacity region. .

  Further, when the pump rotation speed increases and the discharge amount increases, the pressure loss at the metering orifice 23 increases, and the rightward force due to the pressure difference between both ends of the control valve 30 overcomes the leftward force of the spring 30c. The control valve 30 inside moves to the right. At this time, the working fluid downstream of the damper orifice 20 is guided to the first fluid pressure chamber 34 through the opened control valve 30, and the cam ring 15 is swung in a direction to reduce the eccentricity of the cam ring 15, so Reduce discharge volume. A region where the pump rotational speed is high and the discharge amount per one rotation decreases as the pump rotational speed increases is called a variable capacity region.

  In the variable displacement vane pump 1, it is known that the main causes of noise generation are different between the fixed displacement region and the variable displacement region. In the fixed displacement region, the vane separation in which the tip of the vane 14 is separated from the inner peripheral surface of the cam ring 15. The pressure pulsation due to the pressure is considered to be the main cause of noise generation, and in the variable capacity region, the vibration due to the pressure peak generated in the vane chamber 18 is considered to be the main cause of noise generation.

  FIG. 8 is a schematic view showing a local part broken away in order to explain a mechanism of vane separation generated in the structure before improvement in the variable displacement vane pump 1.

  Here, assuming an operation in the first seal section in the maximum eccentric state, when the vane chamber 18 shifts from the suction process to the discharge process, a high oil pressure acts only on the front surface of the vane 14, When the vane 14 is pushed in the slot 29 of the rotor 11, the frictional force opposed to the closing direction increases, and the centrifugal force acting on the vane 14 and the oil pressure of the vane bottom 31 become larger, and the direction of jumping out from the slot 29. The power of may be reduced. Furthermore, when the pressure in the vane chamber 18 changes due to the transition from the suction process to the discharge process or the transition from the discharge process to the suction process, the pressure balance of each vane chamber 18 changes and the shaft 13 is deformed. The rotor 11 is moved by the amount of deformation of the shaft 13 and the gap between the shaft 13 and the rotor 11, and the vane 14 is moved away from the inner peripheral surface of the cam ring 15 due to the friction in the slot 29 of the rotor 11. It is easy to generate.

  When vane separation occurs, oil suddenly flows from high pressure to low pressure, causing pressure pulsation. In particular, since the first half of the first seal section is a region where the vane chamber 18 in front of the vane 14 has a pressure peak, this phenomenon of pressure pulsation is likely to occur.

  Therefore, in the improved structure of the variable displacement vane pump 1 according to the first embodiment, the inner peripheral surface of the cam ring 15 is shaped to reduce the moving radius in the first seal section as described above. It is possible to suppress pressure pulsation.

  Similarly, when the vane chamber 18 shifts from the discharge process to the suction process, a high oil pressure acts only on the rear surface of the vane 14 and receives friction in the slot 29 of the rotor 11, so that vane separation is likely to occur. . In particular, in the region from the middle to the end of the second seal section, the vane separation is likely to occur because the front vane chamber 18 has a pressure peak.

  Therefore, in the improved structure of the variable displacement vane pump 1 according to the first embodiment, as described above, the inner peripheral surface of the cam ring 15 is shaped so that the moving radius gradually decreases in the second seal section. Separation can be suppressed.

  FIG. 9 is a characteristic diagram of pressure with respect to the angle shown for explaining the pressure peak of the vane chamber 18 generated in the structure before improvement in the variable displacement vane pump 1.

  Here, assuming the operation in the first seal section in the minimum eccentric state, when the vane chamber 18 is in the first closed section, neither the suction port 22 nor the discharge port 21 is connected. When the volume of the vane chamber 18 decreases, the pump chamber pressure rises above the discharge pressure, and a pressure peak as shown in FIG. 9 occurs.

  Due to this pressure peak, the volume decreases in the first confinement section from when the vane 14 behind the vane chamber 18 passes the end of the suction port 22 until the front vane 14 reaches the start end of the discharge port 21. The amount has an effect. The difference between the volume that the front vane 14 passes and the volume that the rear vane 14 passes is the volume compression amount. However, since the first confined section is a very short section, the first confined section is determined when the radius of movement at the end point is shortened with respect to the start point and the end point of the first seal section. It can be said that the volume of the vane chamber 18 is reduced and a pressure peak is likely to occur.

  Therefore, in the improved structure of the variable displacement vane pump 1 according to the first embodiment, as described above, as the shape of the inner peripheral surface of the cam ring 15, the region from the midpoint of the first seal section to the end thereof in the minimum eccentric state, Since the moving radius is made to be substantially constant or gradually increased, the radius between the start point and the end point of the first seal section can be brought close to each other, and the volume peak can be suppressed to reduce the pressure peak.

  Similarly, when the vane chamber 18 is in the second confinement section, if the volume of the vane chamber 18 decreases, a pressure peak is likely to occur.

  Due to this pressure peak, the volume decreases in the second confinement section after the vane 14 behind the vane chamber 18 passes the terminal end of the discharge port 21 and the vane 14 ahead reaches the start end of the suction port 22. The amount has an effect. However, since this second confinement section is also a very short section, if the radius of movement at the end point of the start point and end point of the second seal section is short, the second confinement section It can be said that the volume of the vane chamber 18 is reduced and a pressure peak is likely to occur.

  Therefore, in the improved structure of the variable displacement vane pump 1 according to the first embodiment, as described above, the shape of the inner peripheral surface of the cam ring 15 is the dynamic range of the region from the start of the second seal section to its middle point in the minimum eccentric state. Since the radius is made substantially constant or gradually increased, the radius at the start point and the end point of the second seal section can be brought close to each other, and the volume reduction can be suppressed to reduce the pressure peak.

  In the variable displacement vane pump 1 according to the first embodiment, the vane separation is suppressed in the maximum eccentric state where the shape of the inner peripheral surface of the cam ring 15 is a fixed displacement region, and the pressure peak in the minimum eccentric state that is a part of the variable displacement region. Therefore, noise can be reduced in both the fixed capacity range and the variable capacity range.

  In the variable displacement vane pump 1 according to the first embodiment, the pressure in the vane chamber 18 changes from the tank pressure to the discharge pressure and from the discharge pressure to the tank pressure in the first closed section and the second closed section. Since this pressure fluctuation occurs in the first confining section and the second confining section facing each other, an oil pressure is generated due to the pressure difference. Furthermore, when this oil pressure acts on the inner surface of the cam ring 15, the cam ring 15 vibrates, and as a result, flow rate fluctuations and pressure pulsations may occur, causing noise generation. Therefore, for example, if the slots 29 and the vanes 14 of the rotor 11 are provided in an odd number, the pressure imbalance and the pressure pulsation that cause the flow rate fluctuation described above can be alleviated, so that the generation of noise is further suppressed. It becomes possible to do.

  Further, for example, the inner peripheral surface of the cam ring 15 is in the maximum eccentric state from the beginning of the first seal section (end portion of the suction port 22) to the intermediate point (intermediate point between the end portion of the suction port 22 and the start end portion of the discharge port 21). Only in the region up to the point), the moving radius is formed so as to gradually decrease with the rotation of the rotor 11, and in the minimum eccentric state, the intermediate point of the first seal section (the end portion of the suction port 22 and the discharge port 21). Only at least a part of the region from the intermediate point to the end of the discharge port 21 (the start end of the discharge port 21) so that the moving radius becomes substantially constant or gradually longer as the rotor 11 rotates. May be. According to such a configuration, it is particularly effective for preventing noise generation due to pressure pulsation and vibration on the first seal section side.

  In addition, for example, the inner peripheral surface of the cam ring 15 is in the maximum eccentric state from the intermediate point of the second seal section (intermediate point between the end portion of the discharge port 21 and the start end portion of the suction port 22) to its end (of the suction port 22). Only the region up to the start end) is formed so that the moving radius gradually decreases with the rotation of the rotor 11, and in the minimum eccentric state, the middle of the second seal section (the end of the discharge port 21) to the middle thereof. Only at least a part of the region up to the point (the middle point between the end portion of the discharge port 21 and the start end portion of the suction port 22) is formed so that the moving radius becomes substantially constant or gradually longer as the rotor 11 rotates. May be. According to such a configuration, it is particularly effective for preventing noise generation due to pressure pulsation and vibration on the second seal section side.

  Compared with the variable displacement vane pump 1 according to the first embodiment, the variable displacement vane pump according to the second embodiment has the shaft 13 driven to rotate by the engine of the vehicle, and the inner peripheral surface of the cam ring 15 is in the traveling state of the vehicle. At least part of the region from the intermediate point of one seal section (intermediate point between the end portion of the suction port 22 and the start end portion of the discharge port 21) to the end thereof (start end portion of the discharge port 21), and the second seal section For at least one part of the region from the beginning (the end portion of the discharge port 21) to the intermediate point (the intermediate point between the end portion of the discharge port 21 and the start end portion of the suction port 22), the dynamic radius is the rotor. Except for being formed so as to be substantially constant or gradually longer with the rotation of 11, the configuration of other portions is the same as in the case of the first embodiment.

  In the variable displacement vane pump according to the second embodiment, in addition to the operational effects of the variable displacement vane pump 1 according to the first embodiment, it is possible to reduce the peak pressure in the vane chamber 18 in the running state of the vehicle and to prevent noise generation. It is.

  In the variable displacement vane pump according to the third embodiment, as compared with the variable displacement vane pump 1 according to the first embodiment, the shaft 13 is rotationally driven by the engine of the vehicle, and the inner peripheral surface of the cam ring 15 is equal to the engine speed per minute. At least a part of the region from the intermediate point (intermediate point between the end portion of the suction port 22 and the start end portion of the discharge port 21) to the end thereof (start end portion of the discharge port 21) in the state of 1500 revolutions or more , And at least one of at least a part of a region from the beginning of the second seal section (end portion of the discharge port 21) to the intermediate point (intermediate point between the end portion of the discharge port 21 and the start end portion of the suction port 22). In other respects, the configuration of the other portions is the same as that of the first embodiment, except that the moving radius is substantially constant or gradually increased with the rotation of the rotor 11. It is.

  In the variable displacement vane pump according to the third embodiment, in addition to the operational effects of the variable displacement vane pump 1 according to the first embodiment, the vane is used when the engine speed is 1500 rpm or more, particularly in the variable displacement region where noise is likely to be a problem. It is possible to suppress the peak pressure in the chamber 18 and prevent noise generation.

  Compared to the variable displacement vane pump 1 according to the first embodiment, the variable displacement vane pump according to the fourth embodiment has a maximum eccentricity of the inner peripheral surface of the cam ring 15 from the beginning of the first seal section (the end portion of the suction port 22). The region up to the intermediate point (intermediate point between the end portion of the suction port 22 and the start end portion of the discharge port 21) and the intermediate point of the second seal section (the end portion of the discharge port 21 and the start end portion of the suction port 22) At least one in the region from the intermediate point) to the end thereof (starting end portion of the suction port 22) and the front and rear regions connected to the region are connected by a high-order curve, and the first seal is in a minimum eccentric state. At least a part of a region from the middle point of the section (middle point between the end portion of the suction port 22 and the start end portion of the discharge port 21) to the end thereof (the start end portion of the discharge port 21), and At least one of at least a part of the region from the beginning of the seal section (end portion of the discharge port 21) to its intermediate point (intermediate point between the end portion of the discharge port 21 and the start end portion of the suction port 22), and the region Other than the above, the configuration of the other portions is the same as that of the first embodiment except that it is formed so as to be connected to the front and rear regions by a high-order curve.

  In the variable displacement vane pump according to the fourth embodiment, in addition to the operational effects of the variable displacement vane pump 1 according to the first embodiment, the inner peripheral surface of the cam ring 15 can be formed into a smoothly connected shape. It is possible to suppress and significantly prevent noise generation.

  FIG. 10 is a schematic diagram showing the relative positional relationship of the rotor 11, the cam ring 15, the discharge port 21, and the suction port 22 with respect to the support surface 38 provided on the adapter 12 in the variable displacement vane pump according to the fifth embodiment of the present invention. (A) is a schematic diagram in the maximum eccentric state, and (b) is a schematic diagram in the minimum eccentric state. In addition, about the variable displacement vane pump according to the fifth embodiment, the components not shown in the drawing are the same as the configuration of the variable displacement vane pump 1 according to the first embodiment. Only the differences will be described.

  In the variable displacement vane pump according to the fifth embodiment, the cam ring 15 swings or rolls while being supported by a support surface 38 provided on the discharge port 21 side of the inner peripheral surface of the adapter 12. The amount of eccentricity with the rotor 11 is controlled. Here, the inner diameter center Oc of the cam ring 15 is in a no-load state where the differential pressure between the pressure on the suction port 22 side and the pressure on the discharge port 21 side does not act on the shaft 13, the rotor 11, and the cam ring 15. The relative position with respect to the port reference line Lp in the state where the shaft 13 is elastically deformed toward the suction port 22 side due to the differential pressure acting on the suction port 22 side with respect to the rotation center Or is more than the relative position in the no-load state. It is provided so as to be located on the discharge port 21 side. Further, the cam ring 15 is supported by rolling on a support surface 38 provided on the inner peripheral surface of the adapter 12 on the discharge port 21 side, and the support surface 38 rolls from the maximum eccentric state to the minimum eccentric state of the cam ring 15. Accordingly, the inner diameter center Oc of the cam ring 15 is formed so as to gradually move away from the port reference line Lp to the discharge port 21 side. Other configurations are the same as those of the variable displacement vane pump 1 according to the first embodiment.

  In the variable displacement vane pump according to the fifth embodiment, the amount of eccentricity between the cam ring 15 and the rotor 11 can be controlled by the shape of the support surface 38 in addition to the effect of the variable displacement vane pump 1 according to the first embodiment. It is possible to increase the effect of preventing noise generation by more effectively controlling the moving radius between the variable capacity region and the variable capacity region.

  In addition, the relative position of the inner diameter center Oc of the cam ring 15 is positioned closer to the suction port 22 than the port reference line Lp in the non-addition state where no differential pressure acts, and the relative position in the no-addition state when the differential pressure acts. The cam ring 15 is supported by rolling on a support surface 38 provided on the discharge port 21 side of the inner peripheral surface of the adapter 12, and the support surface 38 is the maximum of the cam ring 15. When the inner diameter center Oc of the cam ring 15 is formed so as to gradually move away from the port reference line Lp toward the discharge port 21 as it rolls from the eccentric state to the minimum eccentric state, depending on the operating conditions, The relative position with respect to the first seal section can be controlled.

  Specifically, as shown in the maximum eccentric state of FIG. 10A, a port reference that is a relative angle between a line connecting the rotation center Or of the rotor 11 and the inner diameter center Oc of the cam ring 15 and the port reference line Lp. Since the angle (port timing angle) θ increases at low revolutions, the dynamic radius in the first seal section tends to gradually decrease, thereby further suppressing vane separation.

  Further, as shown in the minimum eccentric state of FIG. 10B, the port reference angle (port timing angle) θ becomes small at high rotation, so that the amount of change in volume in the first seal section can be reduced. The occurrence of pressure peaks can be suppressed.

  Furthermore, even when the cam ring 15 is relatively moved by the pressure difference between the pressure on the suction port 22 side and the pressure on the discharge port 21 side, the port reference angle (port timing angle) θ can be optimized. it can.

  Therefore, this is effective as a function for preventing noise generation due to pressure pulsation and vibration on the first seal section side.

  Compared to the variable displacement vane pump 1 according to the first embodiment, the variable displacement vane pump according to the sixth embodiment has a first seal section region (suction port) in the rotational direction of the rotor 11 with the inner peripheral surface of the cam ring 15 being in the maximum eccentric state. The radius of movement of at least one of the region of the second seal section (the region from the terminal end of the discharge port 21 to the starting end of the suction port 22) and the second seal section. At least a part of the region of the first seal section (region from the end portion of the suction port 22 to the start end portion of the discharge port 21) formed to be gradually shortened with the rotation of the rotor 11 and in the minimum eccentric state; In addition, at least one of at least a part of the region of the second seal section (region from the terminal end of the discharge port 21 to the start end of the suction port 22). For it, except that the dynamic radius is formed to be substantially constant or gradually lengthened in accordance with the rotation of the rotor 11, the configuration of the other portions are the same as in Example 1.

  In the variable displacement vane pump according to the sixth embodiment, in addition to the operational effects of the variable displacement vane pump 1 according to the first embodiment, the inner peripheral surface of the cam ring 15 is separated in the entire region where the separation of the vanes 14 may occur. Since the shape can be prevented, noise generation can be remarkably suppressed (prevented). Incidentally, in the variable displacement vane pump according to the sixth embodiment, it is possible to apply the configurations according to the second, third, and fifth embodiments. In such a case, in addition to the above effects, each of these embodiments can be applied. The same effect as described in the above will be obtained.

  In the variable displacement vane pump according to the seventh embodiment, as compared with the variable displacement vane pump 1 according to the first embodiment, the inner peripheral surface of the cam ring 15 has a pressure on the suction port 22 side relative to the shaft 13, the rotor 11, and the cam ring 15. The cam ring 15 is moved relative to the suction port 22 toward the discharge port 21 compared to the no-load state where the differential pressure does not act due to the pressure difference with the pressure on the discharge port 21 side. The region of the first seal section (region from the terminal end of the suction port 22 to the start end of the discharge port 21) and the region of the second seal section (the terminal end of the discharge port 21 to the start end of the suction port 22 in the maximum eccentric state) The first seal section is formed so that the moving radius gradually decreases with the rotation of the rotor 11, and at least in the eccentric state. At least one of the region (region from the end portion of the suction port 22 to the start end portion of the discharge port 21) and the region of the second seal section (region from the end portion of the discharge port 21 to the start end portion of the suction port 22) The configuration of the other portions is the same as that of the first embodiment except that the moving radius is substantially constant or gradually increased with the rotation of the rotor 11.

  In the variable displacement vane pump according to the seventh embodiment, even when the cam ring 15 is relatively moved due to the pressure difference between the pressure on the suction port 22 side and the pressure on the discharge port 21 side, Vibration in the minimum eccentric state can be suppressed, and noise generation can be effectively prevented. Incidentally, in the variable displacement vane pump according to the seventh embodiment, the configurations described in the second embodiment, the third embodiment, and the fifth embodiment can be applied. In such a case, in addition to the above effects, each of these implementations can be applied. The effect described in the example is similarly achieved.

DESCRIPTION OF SYMBOLS 1 Variable capacity vane pump 10 Front body 11 Rotor 12 Adapter 13 Shaft 14 Vane 15 Cam ring 16 Support pin 17 Compression coil spring 18 Vane chamber 19 Rear cover 20 Damper orifice 21 Discharge port 22 Suction port 23 Metering orifice 26 Pressure chamber 27 Pressure plate 28 Bearing 29 Slot 30 Control valve 30a Valve hole 30b Spool 30c Spring 31 Vane bottom 32 Discharge side piping 32a Discharge side piping upstream portion 33 Passage 34 First fluid pressure chamber 35 Second fluid pressure chamber 36 Spring chamber 37 Control valve high pressure chamber 38 Support surface

Claims (18)

A variable displacement vane pump for transmitting a steering operation of a steering wheel to a steered wheel and supplying hydraulic fluid to a vehicle steering device that generates a steering assist force by hydraulic pressure of the hydraulic fluid,
A pump housing having a pump element housing portion, a drive shaft supported by the pump housing, a rotor provided in the pump housing and driven to rotate by the drive shaft, and having a plurality of slots in the circumferential direction A plurality of vanes provided so as to be able to move in and out with respect to the plurality of slots, and a ring formed so as to be movable with respect to the pump element housing portion, and a plurality of the vanes together with the rotor and the plurality of vanes on the inner peripheral side. A cam ring that forms a pump chamber; and a cam ring control mechanism that is provided in the pump housing and controls an eccentric amount of the cam ring with respect to the rotor,
The pump housing has a suction port opened in a region where the volumes of the plurality of pump chambers increase as the rotor rotates, and a discharge port opened in a region where the volumes of the plurality of pump chambers decrease. And
The inner peripheral surface of the cam ring has a maximum eccentricity with the largest eccentric amount of the cam ring with respect to the rotor, and the suction port from an intermediate point between the end portion of the discharge port and the start end portion of the suction port in the rotation direction of the rotor. The minimum eccentric state in which the distance from the rotation center of the rotor gradually decreases with the rotation of the rotor, and the cam ring is eccentric relative to the rotor in the region up to the starting end of the rotor. Thus, in at least a part of the region between the intermediate point between the terminal end of the suction port and the start end of the discharge port and the start end of the discharge port, the distance from the rotation center of the rotor is the rotation of the rotor. A variable capacity vane pump characterized by being formed so as to be substantially constant or gradually longer.   2. The variable displacement vane pump according to claim 1, wherein the drive shaft is rotationally driven by an engine of a vehicle, and an inner peripheral surface of the cam ring is an end portion of the suction port and a start end of the discharge port in a traveling state of the vehicle. The distance from the rotation center of the rotor is substantially constant or gradually increased with the rotation of the rotor in at least a part of the region from the intermediate point to the starting end of the discharge port. This is a variable displacement vane pump.   2. The variable displacement vane pump according to claim 1, wherein the drive shaft is rotationally driven by an engine of a vehicle, and an inner peripheral surface of the cam ring is connected to the intake port in a state where the rotational speed of the engine is 1500 rpm or more. In at least a part of the region between the intermediate point between the end portion and the start end of the discharge port and the start end of the discharge port, the distance from the rotation center of the rotor is substantially constant as the rotor rotates. A variable displacement vane pump characterized by being formed so as to become longer gradually.   2. The variable displacement vane pump according to claim 1, wherein an inner peripheral surface of the cam ring extends from an intermediate point between a terminal end of the discharge port and a start end of the suction port in the maximum eccentric state to a start end of the suction port. In the region between, the front and rear regions connected to the region are formed to be connected by a high-order curve, and in the minimum eccentric state, the intermediate point between the end portion of the suction port and the start end portion of the discharge port A variable displacement vane pump, characterized in that, in a region between the discharge port and the start end, the front and rear regions connected to the region are connected by a high-order curve.   2. The variable displacement vane pump according to claim 1, wherein an inner peripheral surface of the cam ring extends from an intermediate point between a terminal end of the suction port and a start end of the discharge port in the minimum eccentric state to a start end of the discharge port. A variable displacement vane pump, wherein the distance from the rotation center of the rotor is gradually increased with the rotation of the rotor in at least a part of the intermediate region.   The variable displacement vane pump according to claim 1, wherein the cam ring swings or rolls while being supported by a support surface provided on the discharge port side of the inner peripheral surface of the pump element housing portion. A variable displacement vane pump, wherein an eccentric amount with respect to the rotor is controlled. 7. The variable displacement vane pump according to claim 6, wherein the inner diameter center of the cam ring acts on the drive shaft, the rotor, and the cam ring by a differential pressure between the pressure on the suction port side and the pressure on the discharge port side. while located on the inlet side of the rotor center at a no-load state not, the drive shaft by the differential pressure acts relative position with respect to the state depot over preparative reference line elastically deformed to the inlet side The cam ring is provided to be positioned closer to the discharge port side than the relative position in the unloaded state, and the cam ring is supported by rolling on a support surface provided on the discharge port side of the inner peripheral surface of the pump element housing portion. As the cam ring rolls from the maximum eccentric state to the minimum eccentric state, the center of the inner diameter of the cam ring gradually moves from the port reference line to the discharge port side. Variable displacement vane pump, characterized in that it is formed away.   2. The variable displacement vane pump according to claim 1, wherein an odd number of the plurality of slots and the plurality of vanes in the rotor are provided. 3. A variable displacement vane pump for transmitting a steering operation of a steering wheel to a steered wheel and supplying hydraulic fluid to a vehicle steering device that generates a steering assist force by hydraulic pressure of the hydraulic fluid,
A pump housing having a pump element housing portion, a drive shaft supported by the pump housing, a rotor provided in the pump housing and driven to rotate by the drive shaft, and having a plurality of slots in the circumferential direction A plurality of vanes provided so as to be able to move in and out with respect to the plurality of slots, and a ring formed so as to be movable with respect to the pump element housing portion, and a plurality of the vanes together with the rotor and the plurality of vanes on the inner peripheral side. A cam ring that forms a pump chamber; and a cam ring control mechanism that is provided in the pump housing and controls an eccentric amount of the cam ring with respect to the rotor,
The pump housing has a suction port opened in a region where the volumes of the plurality of pump chambers increase as the rotor rotates, and a discharge port opened in a region where the volumes of the plurality of pump chambers decrease. And
The inner peripheral surface of the cam ring is in a region between the terminal end of the discharge port and the start end of the suction port in the rotational direction of the rotor in the maximum eccentric state where the amount of eccentricity of the cam ring with respect to the rotor is the largest. The discharge port is formed from the terminal end of the suction port in a minimum eccentric state in which the distance from the rotation center of the rotor is gradually shortened with the rotation of the rotor, and the amount of eccentricity of the cam ring with respect to the rotor is the smallest. The variable capacity type wherein the distance from the rotation center of the rotor is formed to be substantially constant or gradually increased with the rotation of the rotor in at least a part of the region between the start end of the rotor Vane pump.   10. The variable displacement vane pump according to claim 9, wherein the drive shaft is rotationally driven by a vehicle engine, and an inner peripheral surface of the cam ring extends from a terminal end of the suction port to a start end of the discharge port in a traveling state of the vehicle. A variable displacement vane pump, wherein the distance from the rotation center of the rotor is formed to be substantially constant or gradually increased with the rotation of the rotor in at least a part of a region between the first and second portions.   10. The variable displacement vane pump according to claim 9, wherein the drive shaft is rotationally driven by an engine of a vehicle, and an inner peripheral surface of the cam ring is formed on the suction port in a state where the rotational speed of the engine is 1500 rpm or more. The distance from the rotation center of the rotor is formed to be substantially constant or gradually increased with the rotation of the rotor in at least a part of the region from the end portion to the start end portion of the discharge port. Features variable displacement vane pump.   The variable displacement vane pump according to claim 9, wherein the cam ring swings or rolls while being supported by a support surface provided on the discharge port side of the inner peripheral surface of the pump element housing portion. A variable displacement vane pump, wherein an eccentric amount with respect to the rotor is controlled.   13. The variable displacement vane pump according to claim 12, wherein the inner diameter center of the cam ring acts on the drive shaft, the rotor, and the cam ring by a differential pressure between the pressure on the suction port side and the pressure on the discharge port side. In the unloaded state, the differential pressure acts on the suction port side with respect to the port reference line connecting the intermediate point between the end portion of the suction port and the start end portion of the discharge port and the center of the rotor. In this state, the drive shaft is elastically deformed toward the suction port, and the relative position with respect to the port reference line is provided closer to the discharge port than the relative position in the no-load state. It is supported by rolling on a support surface provided on the discharge port side of the inner peripheral surface of the element housing portion, and the cam ring rolls in the direction from the maximum eccentric state to the minimum eccentric state. Along with the variable displacement vane pump which inner diameter center of the cam ring is characterized by being formed so as to gradually separate from the port reference line. A variable displacement vane pump for transmitting a steering operation of a steering wheel to a steered wheel and supplying hydraulic fluid to a vehicle steering device that generates a steering assist force by hydraulic pressure of the hydraulic fluid,
A pump housing having a pump element housing portion, a drive shaft supported by the pump housing, a rotor provided in the pump housing and driven to rotate by the drive shaft, and having a plurality of slots in the circumferential direction A plurality of vanes provided so as to be able to move in and out with respect to the plurality of slots, and a ring formed so as to be movable with respect to the pump element housing portion, and a plurality of the vanes together with the rotor and the plurality of vanes on the inner peripheral side. A cam ring that forms a pump chamber; and a cam ring control mechanism that is provided in the pump housing and controls an eccentric amount of the cam ring with respect to the rotor,
The pump housing has a suction port opened in a region where the volumes of the plurality of pump chambers increase as the rotor rotates, and a discharge port opened in a region where the volumes of the plurality of pump chambers decrease. And
The inner peripheral surface of the cam ring is not affected by the differential pressure between the pressure on the suction port side and the pressure on the discharge port side with respect to the drive shaft, the rotor, and the cam ring. Compared with the load state, the cam ring is in the maximum eccentric state with the largest eccentric amount of the cam ring with respect to the rotor when the cam ring is moved relatively to the discharge port side with respect to the suction port. In the region from the terminal end of the discharge port to the start end of the suction port, the distance from the rotation center of the rotor is formed so as to be gradually shortened as the rotor rotates, and The rotation center of the rotor in at least a part of the region between the terminal end of the suction port and the start end of the discharge port in the minimum eccentric state with the smallest amount of cam ring eccentricity Variable displacement vane pump which distance is equal to or formed to be substantially constant or gradually lengthened in accordance with the rotation of the rotor.   15. The variable displacement vane pump according to claim 14, wherein the drive shaft is rotationally driven by an engine of a vehicle, and an inner peripheral surface of the cam ring extends from a terminal end of the suction port to a start end of the discharge port in a traveling state of the vehicle. A variable displacement vane pump, wherein the distance from the rotation center of the rotor is formed to be substantially constant or gradually increased with the rotation of the rotor in at least a part of a region between the first and second portions.   15. The variable displacement vane pump according to claim 14, wherein the drive shaft is rotationally driven by an engine of a vehicle, and an inner peripheral surface of the cam ring is connected to the suction port in a state where the rotational speed of the engine is 1500 rpm or more. The distance from the rotation center of the rotor is formed to be substantially constant or gradually increased with the rotation of the rotor in at least a part of the region from the end portion to the start end portion of the discharge port. Features variable displacement vane pump.   The variable displacement vane pump according to claim 14, wherein the cam ring swings or rolls while being supported by a support surface provided on the discharge port side of the inner peripheral surface of the pump element housing portion. A variable displacement vane pump, wherein an eccentric amount with respect to the rotor is controlled.   18. The variable displacement vane pump according to claim 17, wherein the inner diameter center of the cam ring acts on the drive shaft, the rotor, and the cam ring by a differential pressure between the pressure on the suction port side and the pressure on the discharge port side. In the unloaded state, the differential pressure acts on the suction port side with respect to the port reference line connecting the intermediate point between the end portion of the suction port and the start end portion of the discharge port and the center of the rotor. In this state, the drive shaft is elastically deformed toward the suction port, and the relative position with respect to the port reference line is provided closer to the discharge port than the relative position in the no-load state. It is supported by rolling on a support surface provided on the discharge port side of the inner peripheral surface of the element housing portion, and the cam ring rolls in the direction from the maximum eccentric state to the minimum eccentric state. Along with the variable displacement vane pump which inner diameter center of the cam ring is characterized by being formed so as to gradually separate from the port reference line.