JP3743929B2 - Variable displacement pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable displacement pump used for a power steering device of an automobile.
[0002]
[Prior art]
Conventionally, as a variable displacement pump used in an automobile power steering device or the like, as described in JP-A-9-14155, it has a cam ring that is eccentric to a rotor that is disposed in a pump casing and is driven to rotate. A pump chamber is formed between the cam ring and the outer periphery of the rotor, and when the pump rotates at a low speed, the eccentric amount of the cam ring with respect to the rotor is increased to increase the volume of the pump chamber and increase the discharge amount of hydraulic oil. When the pump rotates at high speed, there is a type in which the amount of hydraulic oil discharged is reduced by reducing the amount of eccentricity of the cam ring with respect to the rotor to reduce the volume of the pump chamber.
[0003]
In the above-described conventional technology, in order to reduce the pressure pulsation of the variable displacement vane pump and the vibration and noise induced thereby, the suction port and the discharge at the bottom dead center in the pump chamber surrounded by the cam ring and the rotor. The space between the two confining parts of the first confining part that closes the closing port and the second confining part that closes the discharge port and the suction port at the top dead center is the rotor under the maximum eccentric state of the cam ring. It is a space surrounded by concentric circles centered on the rotation center (in other words, the moving radius of the vane is constant). In this prior art, since the distance between the rotor and the cam ring at the confined portion is constant, no excessive precompression (overcompression) based on the volume change of the pump chamber occurs, and as a result, the pulsation based on the vane separation The phenomenon can be prevented.
[0004]
[Problems to be solved by the invention]
In the prior art, the maximum amount of eccentricity of the cam ring when the pump is rotating at low speed is such that the distance between the rotor and the cam ring at the closed portion is constant (that is, concentric). When it becomes smaller, the inner periphery of the cam ring and the outer periphery of the rotor are not concentric, and the separation of the vanes cannot be prevented, and a large pressure pulsation occurs due to an increase in gap leakage at the vane tip. In the prior art, the vane separation is considered to be caused by excessive precompression (overcompression) in the confined chamber. However, as will be described below, the vane separation is mainly in the vane section. This is due to an unbalanced load based on an unbalance of pressures acting on the front surface and the back surface.
[0005]
That is, in FIG. 14, the vane 2 accommodated in the groove of the rotor 1 receives a centrifugal force due to the back pressure Pd and the centrifugal force and comes into contact with the inner periphery of the cam ring 3, and the vane 2 rotates with the rotation of the rotor 1. Under the condition that one vane 2A is in the suction section until it reaches the end point of the suction port 4, the same suction pressure acts on the front and back of the vane 2A. The tip of the vane 2 </ b> A is pressed against the inner periphery of the cam ring 3 by the back pressure Pd and the centrifugal force, and is not separated from the inner periphery of the cam ring 3. When the vane 2 is further rotated together with the rotation of the rotor 1 and the vane 2A is in the first closed section that has not yet reached the starting point of the discharge port 5 after passing through the suction section, the front of the vane 2A has the discharge port 5 Since the high pressure on the side and the low pressure on the suction port 4 side act on the back surface, an eccentric load acts on the vane 2A in the circumferential direction, and the vane 2A is inclined and caught at the root accommodated in the groove of the rotor 1, The vane 2A cannot be pressed against the inner periphery of the cam ring 3 due to the back pressure Pd and centrifugal force, and is separated from the inner periphery of the cam ring 3, and is discharged from the tip end gap of the separated vane and is sucked from the suction port 5 The above-described large leakage occurs on the side of 4. The same phenomenon occurs in the second confinement section.
[0006]
The problems of the prior art will be pointed out in detail below. In the conventional technique, the inner circumferences of the cam rings of the first closing portion and the second closing portion are concentric with the rotation center of the rotor under the maximum eccentric state (during low speed rotation). Therefore, since the moving radius of the vane in the closed section is constant during low-speed rotation, the vane is not separated (FIGS. 15A and 16A), and generation of a large pressure pulsation due to the separation can be prevented. However, under the minimum eccentric condition (during high-speed rotation), the inner circumference of the cam ring is not concentric with the rotation center of the rotor, together with the first and second confinement parts, and the pressure on the front and back is unbalanced. When the vane is caught due to the offset load, the tip of the vane is separated from the inner surface of the cam ring (that is, separated), and a large pressure pulsation is generated.
[0007]
That is, FIG. 15 shows the behavior of the vane tip at the first confinement part, with the horizontal axis representing the rotor rotation angle and the vertical axis representing the vane protrusion radius with respect to the rotation center of the rotor. The solid line is for the cam ring that is concentric with the rotation center of the rotor, and the broken line is for the circular cam ring. In this case, at the time of low speed rotation at the first confinement portion in FIG. 15A, the distance between the rotor and the cam ring is constant at Ha = Hb = Hc as shown in FIG. Hard to happen. At the time of high-speed rotation at the first confinement portion in FIG. 15B, the cam ring is in the minimum eccentric state, and the distance between the rotor and the cam ring is the center (Hb) of the first confinement portion as shown in FIG. ) And shorter on both sides (Ha, Hc), the vane is pushed in the centripetal direction in the first half of the first confinement portion and is not separated, but in the latter half, the kinematic radius has a positive slope (positive slope). Therefore, when an unbalanced load is applied to the vane and the vane is caught, the vane is separated.
[0008]
FIG. 16 shows the behavior of the vane tip at the second confinement portion, with the horizontal axis representing the rotor rotation angle and the vertical axis representing the moving radius that is the vane protrusion radius with respect to the center of the rotor. The solid line is for the cam ring that is concentric with the rotation center of the rotor, and the broken line is for the circular cam ring. In this case, at the time of low speed rotation at the second confinement portion in FIG. 16A, the distance between the rotor and the cam ring is constant at Hd = He = Hf as shown in FIG. Hard to happen. However, when the cam ring is in the minimum eccentric state during high-speed rotation, the distance between the rotor and the cam ring is long at the center (He) of the second confinement portion and on both sides (Hd, Hf) as shown in FIG. Since it becomes short, a vane will raise | generate separation in the first half of a 2nd confinement part.
[0009]
An object of the present invention is to prevent pressure pulsation and associated vibration / vibration in a variable displacement vane pump by preventing the occurrence of vane separation over a wide range of pump rotation speed, in other words, over a wide eccentric region of the cam ring. It is to reduce noise.
[0010]
[Means for Solving the Problems]
According to a first aspect of the present invention, a pump chamber is formed between a pump casing, a perfectly circular rotor disposed in the pump casing and driven to rotate, and disposed around the rotor, and an outer peripheral portion of the rotor. And a cam ring that can be eccentric with respect to the rotor, a suction port that is disposed in the pump casing and sucks hydraulic oil into the pump chamber, and a discharge port that is disposed in the pump casing and discharges hydraulic oil from the pump chamber. And a plurality of vanes which are accommodated in the grooves of the rotor and protrude so as to be movable in the radial direction, and whose tips are in contact with the inner periphery of the cam ring, the hydraulic oil sucked from the suction port is placed in a space between the adjacent vanes. The hydraulic oil is transported by the rotation of the rotor and discharged from the discharge port, and the amount of hydraulic oil discharged is increased by increasing the eccentric amount of the cam ring with respect to the rotor. In the variable displacement pump, the inner periphery of the cam ring has a shape of a suction section that sucks hydraulic oil from the suction port, a first closed at the bottom dead center where the hydraulic oil sucked from the suction port is discharged and pre-compressed and transferred to the port. The shape of the intake section, the shape of the discharge section that discharges hydraulic oil from the discharge port, and the second confinement section that transfers the hydraulic oil sandwiched in the space between adjacent vanes at the top dead center to the suction port The inner circumference of the cam ring in the suction section and the discharge section is composed of a perfect circle curve and a transient curve, and the inner circumference of the cam ring in the closed section is a rotor regardless of the eccentric amount of the cam ring. The radius of curvature is composed of a negative slope curve that decreases along the direction of rotation of the rotor so that the moving radius of the vane always decreases as the rotation angle increases. In which was to so that.
[0011]
According to a second aspect of the present invention, in the first aspect of the present invention, the cam ring has a shape in which the moving radius of the vane is increased with respect to an increase in the rotation angle of the rotor in the first confinement section regardless of the eccentric amount of the cam ring. The radius of curvature is constituted by a negative gradient curve that decreases along the direction of rotation of the rotor so that is always reduced.
[0012]
According to a third aspect of the present invention, in the first aspect of the present invention, the cam ring has a shape in which the moving radius of the vane is increased in the second confinement section with respect to an increase in the rotation angle of the rotor regardless of the eccentric amount of the cam ring. The radius of curvature is constituted by a negative gradient curve that decreases along the direction of rotation of the rotor so that is always reduced.
[0013]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects of the present invention, the shape of the cam ring is defined by the both end portions of the suction section or the discharge section and the first confinement section or the second confinement section. In the connecting portion, a transient curve that smoothly connects the perfect circular curve of the suction section or the discharge section to the negative gradient curve of the first confinement section or the second confinement section is a high-order curve.
[0014]
According to a fifth aspect of the present invention, a pump chamber is formed between a pump casing, a perfectly circular rotor disposed in the pump casing and driven to rotate, and disposed around the rotor, and an outer peripheral portion of the rotor. And a cam ring that can be eccentric with respect to the rotor, a suction port that is disposed in the pump casing and sucks hydraulic oil into the pump chamber, and a discharge port that is disposed in the pump casing and discharges hydraulic oil from the pump chamber. And a plurality of vanes which are accommodated in the grooves of the rotor and protrude so as to be movable in the radial direction, and whose tips are in contact with the inner periphery of the cam ring, the hydraulic oil sucked from the suction port is placed in a space between the adjacent vanes. The hydraulic oil is transported by the rotation of the rotor and discharged from the discharge port, and the amount of hydraulic oil discharged is increased by increasing the eccentric amount of the cam ring with respect to the rotor. In the variable displacement pump, the inner circumference of the cam ring has a shape of a suction section for sucking hydraulic oil from the suction port, and a first dead center at the bottom dead center where the hydraulic oil sucked from the suction port is discharged and pre-compressed to the port. The shape of the confinement section, the shape of the discharge section that discharges hydraulic oil from the discharge port, and the second confinement section that transfers the hydraulic oil sandwiched in the space between adjacent vanes at the top dead center to the suction port The inner circumference of the cam ring in the suction section and the discharge section is composed of a perfect circle curve and a transient curve, and the inner circumference of the cam ring in the enclosed space is independent of the amount of eccentricity of the cam ring. Consists of a plurality of negative gradient curves in which the radius of curvature decreases along the direction of rotation of the rotor so that the moving radius of the vane always decreases with increasing rotation angle. In which it was like being.
[0015]
According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the cam ring has a shape in which the moving radius of the vane is increased with respect to an increase in the rotation angle of the rotor in the first confinement section regardless of the eccentric amount of the cam ring. The radius of curvature is composed of a plurality of negative gradient curves that decrease along the direction of rotation of the rotor.
[0016]
According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the shape of the cam ring is set such that, in the second confinement section, the moving radius of the vane is increased with respect to an increase in the rotation angle of the rotor regardless of the eccentric amount of the cam ring. The radius of curvature is composed of a plurality of negative gradient curves that decrease along the direction of rotation of the rotor.
[0017]
The invention according to claim 8 is the invention according to any one of claims 5 to 7, wherein the shape of the cam ring is defined by the both ends of the suction section or the discharge section and the first confinement section or the second confinement section. In the connecting portion, a transient curve that smoothly connects the perfect circular curve of the suction section or the discharge section to the negative gradient curve of the first confinement section or the second confinement section is a high-order curve.
[0018]
[Action]
According to the first and second aspects of the invention, there is the following effect (1).
(1) When the vane is in the first confinement section, the vane has a discharge pressure on the front side and a low pressure on the suction port side on the back surface. And tilted at the root accommodated in the groove of the rotor to cause catching. However, the vane is imparted with a centripetal motion that always enters the rotor groove in contact with the negative gradient curve of the inner periphery of the cam ring in this first closed section. That is, the vane is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring, resulting in a large pressure pulsation caused by the vane separation generated in the perfect circle cam ring. It is possible to prevent the vibration and noise caused by this.
[0019]
According to the first and third aspects of the invention, there is the following effect (2).
(2) When the vane is in the second confinement section, the high pressure on the discharge port side acts on the back surface of the vane, and the low pressure on the suction port side acts on the front surface. And tilted at the root accommodated in the groove of the rotor to cause catching. However, the vane is given a force in the centripetal direction, which is always in contact with the negative gradient curve of the inner circumference of the cam ring and enters the groove of the rotor in this second closed section. That is, the vane is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring. As a result, generation of a large pressure pulsation due to the separation of the vane can be prevented.
[0020]
According to invention of Claim 4, there exists the effect | action of following (3).
(3) By smoothly connecting the negative gradient curve of the first confinement section or the second confinement section and the perfect circle curve of the discharge section or the suction section with a high-order curve, the speed change of the vane in the connection section is gentle. (Acceleration becomes smaller) and the vibration force due to the inertial force of the vane can be reduced, so that the vibration and noise of the pump due to the shape change of the cam ring inner periphery can be prevented.
[0021]
According to the inventions of claims 5 and 6, the following effects (4) and (5) are obtained.
(4) When the vane is in the first confinement section, the vane has a discharge pressure on the front side and a low pressure on the suction port side on the back surface. And tilted at the root accommodated in the groove of the rotor to cause catching. However, the vane is given a centripetal motion that enters the groove of the rotor while always in contact with the negative gradient curve and higher order curve of the inner periphery of the cam ring in this first closed section. That is, the vane is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring, resulting in a large pressure pulsation caused by the vane separation generated in the perfect circle cam ring. It is possible to prevent the vibration and noise caused by this.
[0022]
(5) In the first confinement section, the slopes of the plurality of negative gradient curves constituting the inner peripheral shape of the cam ring are different (specifically, the first half of the first confinement section is a negative gradient curve having a small gradient). If the latter half is composed of a negative gradient curve with a large gradient), a wide operating range (wide cam ring) during low-speed rotation of the pump (during maximum eccentricity of the cam ring) to high-speed rotation (during minimum eccentricity) In the eccentric region), it is possible to prevent the vanes from separating in the first confinement section, and as a result, it is possible to significantly reduce pressure pulsation and vibration and noise of the pump due to this.
[0023]
According to the inventions of claims 5 and 7, the following effects (6) and (7) are obtained.
(6) When the vane is in the second closed section, the high pressure on the discharge port side acts on the back surface of the vane, and the low pressure on the suction port side acts on the front surface. And tilted at the root accommodated in the groove of the rotor to cause catching. However, the vane is given a force in the centripetal direction, which is always in contact with the negative gradient curve of the inner circumference of the cam ring and enters the groove of the rotor in this second closed section. That is, the vane is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring. As a result, generation of a large pressure pulsation due to the separation of the vane can be prevented.
[0024]
(7) Different slopes of a plurality of negative gradient curves constituting the inner peripheral shape of the cam ring in the second confinement section (specifically, for example, the first half of the second confinement section is a perfect circle curve or close thereto) If the latter half is composed of a negative gradient curve with a relatively small slope), the pump rotates at a low speed (when the cam ring is fully eccentric) to a high speed (when the cam ring is at the minimum eccentricity). Since the vane separation in the second confinement section can be prevented over a wide operating range (wide eccentric range of the cam ring), pressure pulsation can be significantly reduced.
[0025]
(8) By smoothly connecting the negative slope curve of the first confinement section or the second confinement section and the perfect circle curve of the discharge section or the suction section with a high-order curve, the speed change of the vane in the connection section is slow. (Acceleration becomes smaller) and the vibration force due to the inertial force of the vane can be reduced, so that the vibration and noise of the pump due to the shape change of the cam ring inner periphery can be prevented.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
1 is a sectional view showing a variable displacement pump, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. 1, and FIG. FIG. 5 is a schematic view showing the cam ring, FIG. 6 is a diagram showing the change in the vane radius (dynamic radius) over the entire circumference of the cam ring of the first embodiment, and FIG. 7 is the first embodiment. FIG. 8 is an enlarged diagram of the second confinement section in the dynamic radius of the first embodiment, and FIG. 9 is the entire circumference of the cam ring of the second embodiment. FIG. 10 is a diagram showing a change in the radius (dynamic radius) of the vane, FIG. 10 is an enlarged diagram of a first confinement section in the dynamic radius of the second embodiment, and FIG. 11 is a second confinement in the dynamic radius of the second embodiment. FIG. 12 is an enlarged diagram of the section, and FIG. 12 shows the vane separation preventing effect at the time of low speed rotation and high speed rotation in the first closed section of the second embodiment FIG. 13 is a diagram showing the effect of preventing vane separation during low-speed rotation and high-speed rotation in the second confinement section of the second embodiment, and FIG. 14 shows the vane catching phenomenon in the first confinement section. FIG. 15 is a diagram showing a vane separation state during low-speed rotation and high-speed rotation in the first closing section of the conventional cam ring, and FIG. 16 is a low-speed rotation in the second closing section of the conventional cam ring. FIG. 17 is a schematic diagram showing the eccentric state of the cam ring during low-speed rotation and high-speed rotation.
[0027]
The variable displacement pump 10 is a vane pump serving as a hydraulic pressure generation source of a hydraulic power steering device of an automobile. As shown in FIGS. 1 to 3, the variable displacement pump 10 is rotationally driven by being fixed to a pump shaft 12 inserted into a pump casing 11 by serrations. The rotor 13 is provided. The pump casing 11 is configured by integrating a pump housing 11A and a cover 11B with bolts 14, and supports the pump shaft 12 via bearings 15A to 15C. The pump shaft 12 can be directly rotated by an automobile engine.
[0028]
The rotor 13 accommodates vanes 17 in grooves 16 provided at each of a plurality of positions in the circumferential direction, and the vanes 17 protrude so as to be movable in the radial direction along the grooves 16.
[0029]
In the fitting hole 20 of the pump housing 11A of the pump casing 11, a pressure plate 18 and an adapter ring 19 are fitted in a laminated state, and these are positioned on the side by the cover 11B while being positioned in a circumferential direction by a fulcrum pin 21 described later. It is fixed and held from one side. One end of the fulcrum pin 21 is attached and fixed to the cover 11B.
[0030]
A cam ring 22 is fitted on the adapter ring 19 fixed to the pump housing 11 </ b> A of the pump casing 11. The cam ring 22 surrounds the rotor 13 with a certain amount of eccentricity with the rotor 13, and forms a pump chamber 23 between the pressure plate 18 and the cover 11 </ b> B and the outer periphery of the rotor 13. A suction port 24 provided in the cover 11B is opened in the suction area upstream of the rotor rotation direction of the pump chamber 23. The suction port 24 is connected to the housing 11A and suction passages 25A and 25B provided in the cover 11B. The suction port 26 of the pump 10 is communicated. On the other hand, a discharge port 27 provided in the pressure plate 18 opens in a discharge region on the downstream side in the rotor rotation direction of the pump chamber 23. The discharge port 27 includes a high pressure chamber 28A provided in the housing 11A, a discharge passage. The discharge port 29 of the pump 10 is connected via 28B.
[0031]
Thus, in the variable displacement pump 10, when the rotor 13 is rotationally driven by the pump shaft 12 and the vane 17 of the rotor 13 is pressed against the cam ring 22 by centrifugal force and back pressure and rotates, In the suction section on the upstream side in the rotor rotation direction, the volume surrounded by the adjacent vanes 17 and the cam ring 22 is enlarged with rotation to suck the working fluid from the suction port 24, and this working oil is introduced into the space between the adjacent vanes 17. It is transported by the rotation of the rotor 13 sandwiched between them, and the volume surrounded by the cam ring 22 between the adjacent vanes 17 and the cam ring 22 in the discharge section on the downstream side in the rotor rotation direction of the pump chamber 23 is reduced with rotation to discharge the working fluid from the port 27. Discharge.
[0032]
However, the variable displacement pump 10 has a discharge flow rate control device 40 as shown below (A) and a vane pressurizing device 60 as shown below (B).
[0033]
(A) Discharge flow rate control device 40
The discharge flow rate control device 40 places the aforementioned fulcrum pin 21 on the lowest vertical part of the aforementioned adapter ring 19 fixed to the pump casing 11, and supports the lowest vertical part of the cam ring 22 on this fulcrum pin 21. The cam ring 22 can be oscillated and displaced within the adapter ring 19.
[0034]
The discharge flow rate control device 40 presses the spring 42 accommodated in the spring chamber 41 provided in the pump housing 11 </ b> A constituting the pump casing 11 through the spring hole 19 </ b> A provided in the adapter ring 19 and presses the outer periphery of the cam ring 22. Thus, an urging force that maximizes the volume of the pump chamber 23 can be applied to the cam ring 22. The spring 42 is backed up by a cap 41 </ b> A that is screwed into the opening of the spring chamber 41. The adapter ring 19 has a cam ring movement restricting stopper 19B formed in a convex shape on a part of an inner peripheral portion forming a second fluid pressure chamber 44B, which will be described later, and a cam ring 22 that minimizes the volume of the pump chamber 23 as will be described later. The movement limit (minimum eccentric position) can be regulated. The adapter ring 19 is formed with a cam ring movement restricting stopper 19C in a convex shape at a part of an inner peripheral portion forming a first fluid pressure chamber 44A described later, and the cam ring 22 maximizes the volume of the pump chamber 23 as described later. The movement limit (maximum eccentric position) can be regulated.
[0035]
Further, the discharge flow rate control device 40 divides and forms first and second fluid pressure chambers 44 </ b> A and 44 </ b> B between the cam ring 22 and the adapter ring 19. That is, the first fluid pressure chamber 44 </ b> A and the second fluid pressure chamber 44 </ b> B are divided between the cam ring 22 and the adapter ring 19 by the fulcrum pin 21 and the seal material 45 provided at the axially symmetric position. At this time, the first and second fluid pressure chambers 44A and 44B are partitioned by the cover 11B and the pressure plate 18 on both sides between the cam ring 22 and the adapter ring 19, and the above-described cam ring movement restriction stopper 19B of the adapter ring 19 is provided. , 19C, when the cam ring 22 abuts, the communication groove 18A connecting the first fluid pressure chambers 44A separated on both sides of the stopper 19C, and the second fluid pressure chambers 44B separated on both sides of the stopper 19B. The pressure plate 18 is provided with a communication groove 18B for communication.
[0036]
Here, in the discharge path of the pump 10 described above, the pressure fluid discharged from the pump chamber 23 and sent from the discharge port 27 of the pressure plate 18 to the high pressure chamber 28A of the pump housing 11A is drilled in the pressure plate 18. The metering orifice 46 passes through the second fluid pressure chamber 44B, the spring chamber 41 penetrating the adapter ring 19, and the discharge communication hole 100 formed in the fitting hole 20 of the pump housing 11A. Thus, the pressure is fed to the discharge passage 28B.
[0037]
The discharge flow rate control device 40 increases or decreases the opening area of the metering orifice 46 opened to the second fluid pressure chamber 44B on the side wall of the cam ring 22 in the discharge path of the pump 10 to form a variable metering orifice. . That is, the opening of the orifice 46 is adjusted at the side wall with the displacement of the cam ring 22. The discharge flow rate control device 40 (1) applies the high fluid pressure in the high pressure chamber 28A before passing through the orifice 46 to the first fluid pressure supply passage 47A (FIG. 4), the switching valve device 48, the pump housing 11A, and the adapter ring 19. To the first fluid pressure chamber 44A through the communication passage 49 drilled in, and {circle around (2)} the reduced pressure after passing through the orifice 46 is guided to the second fluid pressure chamber 44B as described above, to both the fluid pressure chambers 44A and 44B. The cam ring 22 is moved against the biasing force of the spring 42 by the differential pressure of the acting pressure, and the volume of the pump chamber 23 is changed to control the discharge flow rate of the pump 10.
[0038]
The switching valve device 48 accommodates a spring 52 and a switching valve 53 in a valve storage hole 51 formed in the pump housing 11A, and a cap 54 in which the switching valve 53 biased by the spring 52 is screwed to the pump housing 11A. It is supported by. The switching valve 53 includes a switching valve body 55A and a valve body 55B. The first fluid pressure supply passage 47A communicates with a pressurizing chamber 56A provided on one end side of the switching valve body 55A, and the other end side of the valve body 55B. The second fluid pressure chamber 44 </ b> B is communicated with the back pressure chamber 56 </ b> B in which the provided spring 52 is accommodated through a communication passage 57 formed in the pump housing 11 </ b> A and the adapter ring 19. Further, the above-described suction passage (drain passage) 25A is formed through the intermediate chamber 56C between the switching valve body 55A and the valve body 55B and communicates with the tank. The switching valve body 55A is capable of opening and closing the above-described communication passage 49 formed in the pump housing 11A and the adapter ring 19. That is, in the low speed rotation region where the discharge pressure of the pump 10 is low, the switching valve 53 is set to the original position shown in FIG. 2 by the biasing force of the spring 52, and the communication passage 49 with the first fluid pressure chamber 44A is switched by the switching valve body 55A. And the switching valve 53 is moved by the high-pressure fluid applied to the pressurizing chamber 56A in the middle and high-speed rotation range of the pump 10 to open the communication passage 49, and this high-pressure fluid can be guided to the first fluid pressure chamber 44A. To do.
[0039]
Therefore, the discharge flow rate characteristics of the pump 10 provided with the discharge flow rate control device 40 are as follows.
[0040]
(1) In the low-speed traveling region of an automobile where the rotational speed of the pump 10 is low, the pressure of the fluid discharged from the pump chamber 23 and reaching the pressurizing chamber 56A of the switching valve device 48 is still low, and the switching valve 53 is in the original position. The cam ring 22 maintains the original state (maximum eccentric position) urged by the spring 42. For this reason, the discharge flow rate of the pump 10 increases in proportion to the rotational speed.
[0041]
(2) When the pressure of the fluid discharged from the pump chamber 23 and reaching the pressurizing chamber 56A of the switching valve device 48 increases due to the increase in the rotation speed of the pump 10, the switching valve device 48 resists the urging force of the spring 52. Then, the switching valve 53 is moved to open the communication passage 49, and this high-pressure fluid is guided to the first fluid pressure chamber 44A. As a result, the cam ring 22 moves due to the differential pressure between the pressures acting on the first fluid pressure chamber 44A and the second fluid pressure chamber 44B, and the volume of the pump chamber 23 is gradually reduced. Accordingly, the discharge flow rate of the pump 10 can maintain a constant large flow rate by offsetting the increase in flow rate due to the increase in rotation rate and the decrease in flow rate due to the volume reduction of the pump chamber 23 with respect to the increase in rotation rate. it can.
[0042]
(3) When the rotation speed of the pump 10 continues and further increases and the cam ring 22 further moves and the cam ring 22 pushes the spring 42 beyond a certain amount, the side wall of the cam ring 22 is removed from the pump chamber 23. The opening area of the orifice 46 in the middle of the discharge path is started to be reduced. Accordingly, the discharge flow rate pumped to the discharge passage 28B of the pump 10 decreases in proportion to the throttle amount of the orifice 46.
[0043]
(4) When the rotational speed of the pump 10 reaches a high-speed driving range of the automobile that exceeds a certain value, the cam ring 22 reaches a movement limit (minimum eccentric position) that abuts against the stopper 19B of the adapter ring 19, and the side wall of the cam ring 22 The throttle amount of the orifice 46 is also maximized, and the discharge flow rate of the pump 10 is maintained at a constant small flow rate.
[0044]
In the discharge flow rate control device 40, a throttle 49A is provided in the communication passage 49 that guides the pressurizing chamber 56A of the switching valve device 48 to the first fluid pressure chamber 44A, and the second fluid pressure chamber 44B is connected to the back pressure of the switching valve device 48. A throttle 57A is provided in the communication path 57 leading to the chamber 56B.
[0045]
(B) Vane pressurizing device 60
The vane pressurizing device 60 includes a ring-shaped oil groove 61 on the sliding surface of the pressure plate 18 and the groove 16 of the side plate 20 corresponding to both sides of the base portion 16A of the groove 16 accommodating the vane 17 of the rotor 13. 62 is provided. The high pressure chamber 28 </ b> A of the pump chamber 23 provided in the pump housing 11 </ b> A communicates with the above-described oil groove 61 through an oil hole 63 provided in the pressure plate 18. As a result, the pressure fluid discharged from the pump chamber 23 to the high pressure chamber 28 </ b> A passes through the oil grooves 61 and 62 of the pressure plate 18 and the side plate 20, and the grooves 16 for all the vanes 17 in the circumferential direction of the rotor 13 are formed. The pressure is led to the base and set to the back pressure Pd against the vanes 17 (FIG. 13), and each vane 17 can be pressurized toward the cam ring 22.
[0046]
Thereby, in the pump 10, the vane 17 is pressed against the cam ring 22 by centrifugal force at the beginning of rotation, but after the discharge pressure is generated, the vane 17 and the cam ring are caused by the back pressure Pd applied by the vane pressurizing device 60. The contact pressure with 22 is increased, and the backflow of the pressure fluid can be prevented.
[0047]
In the pump 10, a relief valve 70 for relieving excessive fluid pressure on the pump discharge side is built in the switching valve 53 between the high pressure chamber 28A and the suction passage (drain passage) 25A. is doing. The relief valve 70 is constituted by a direct acting type incorporated in a main valve 71 comprising the switching valve 53 itself. Further, the pump 10 pierces the cover 11B with a lubricating oil supply passage 121 from the suction passage 25B toward the bearing 15C of the pump shaft 12, and a lubricating oil return passage 122 that returns from the periphery of the bearing 15B of the pump shaft 12 to the suction passage 25A. It is drilled in the pump housing 11A.
[0048]
That is, in the pump 10, the pump chamber 23 sucks in the suction port 24 between the suction section that sucks the hydraulic oil from the suction port 24 and the discharge section that discharges the hydraulic oil from the discharge port 27. In the first confinement section 23A for pre-compressing and transferring the hydraulic oil to the port 27 and the second confinement section 23B for closing the discharge section and the suction section, the vanes are separated over a wide rotational speed range. The following configuration is provided for preventing pressure pulsation.
[0049]
(First Embodiment) (FIGS. 5 to 8)
The inner peripheral shape of the cam ring 22 was set as follows (1) to (5). In FIG. 5, the cam ring 22 is in the maximum eccentric state, O1 is the center position of the rotor 13, O2 is the center position of the inner peripheral perfect circle part of the cam ring 22, and E is the maximum eccentric amount of the cam ring 22.
[0050]
(1) In the rotational direction of the rotor 13 under the maximum eccentric state of the cam ring 22, in the suction section where the vane is located at the suction port and the discharge section where the vane is located at the discharge port, The circumferential shape is constituted by perfect circular curves H to A, D to E (center O2).
[0051]
(2) In the first confinement section 23A, which is sandwiched between the suction section and the discharge section and where the space between the adjacent vanes 17 and 17 is not connected to the suction port 24 and connected to the suction port 27, the inner circumference of the cam ring 22 Regardless of the amount of eccentricity E, the center of the rotor 13 of the vane 17 is always in contact with the tip of the vane 17 so that the vane 17 can be pushed in the centripetal direction along the groove 16 of the rotor 13. A curve (curvature radius decrease curve in which the radius of curvature decreases along the direction of rotation of the rotor 13) that can provide a centripetal movement in which the protrusion radius (dynamic radius) with respect to O1 gradually decreases as the rotation angle of the rotor 13 increases (hereinafter, negative It is composed of B to C (denoted as a gradient curve).
[0052]
(3) In the connection portion where the suction section or the discharge section is connected to the first closed section 23A, the inner peripheral shape of the cam ring 22 is changed to the negative gradient curves B to C of the first closed section 23A and the suction section or the discharge section. 2 or higher order curves A to B and C to D (transient curves) smoothly connecting the perfect circle curves D to E and H to A.
[0053]
(4) In the second confinement section 23B, which is sandwiched between the suction section and the discharge section and the space between the adjacent vanes 17 and 17 is not discharged to the suction port 24 and connected to the port 27, the inner periphery of the cam ring 22 Regardless of the amount of eccentricity E, the shape of the rotor 13 of the vane 17 is always in contact with the tip of the vane 17 so that the vane 17 can be pushed in the centripetal direction along the groove 16 of the rotor 13. From a negative gradient curve F to G (curvature radius decreasing curve in which the radius of curvature decreases along the direction of rotation of the rotor 13), which can give a centripetal movement in which the radius of movement with respect to the center O1 gradually decreases with an increase in the rotation angle of the rotor 13. Constitute.
[0054]
(5) In the connection portion where the suction section or the discharge section is connected to the second closed section 23B, the inner peripheral shape of the cam ring 22 is changed to the negative gradient curves FG of the second closed section 23B and the suction section or the discharge section. 2 or higher order curves E to F and G to H (transient curves) smoothly connecting the perfect circle curves D to E and H to A.
[0055]
The solid line in FIGS. 6 to 8 indicates that the tip of the vane 17 is kept in contact with the inner periphery of the cam ring 22 at each angular position in the circumferential direction of the cam ring 22 when the cam ring 22 is fully eccentric (when the pump 10 rotates at a low speed). The magnitude | size of the protrusion radius (dynamic radius) with respect to the center O1 of the rotor 13 of this vane 17 is shown, AB is a high order curve, BC is a negative gradient curve, CD is a high order curve, DE is E A perfect circle curve, E to F are high-order curves, F to G are negative gradient curves, G to H are a plurality of higher order curves connected to each other, and H to A are true circle curves. The broken lines in FIGS. 6 to 8 indicate the case of a cam ring having a full circle formed by a perfect circle.
[0056]
(Operation in the first confinement section 23A)
(1) When the vane 17 is in the first confining section 23A, the vane 17 has a discharge port 27 side high pressure on the front surface and a low pressure suction port 24 side on the back surface. An eccentric load is received in the circumferential direction, and the base is accommodated in the groove 16 of the rotor 13 to be caught. However, the vane 17 is imparted with a centripetal motion entering the groove 16 of the rotor 13 in this first confining section 23A, always in contact with the negative gradient curves B to C on the inner periphery of the cam ring. That is, the vane 17 is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring. As a result, a large pressure pulsation caused by the separation of the vane generated in the perfect circle cam ring. Can be prevented, and vibration and noise caused by this can be significantly reduced.
[0057]
(2) Smoothly connecting the negative gradient curves B to C of the first confinement section 23A and the perfect circular curves H to A and D to E of the discharge section or the suction section with higher order curves A to B and C to D. As a result, the speed change of the vane in the connection section becomes gentle (acceleration becomes small), and the vibration force due to the inertia force of the vane can be reduced, so that the vibration and noise of the pump due to the shape change of the cam ring inner periphery can be prevented. .
[0058]
(Operation in the second confinement section 23B)
(1) When the vane 17 is in the second closing section 23B, the high pressure on the discharge port 27 side acts on the back surface of the vane 17 and the low pressure on the suction port 24 side acts on the front surface. An eccentric load is received in the circumferential direction, and the base is accommodated in the groove 16 of the rotor 13 and is caught. However, the vane 17 is applied with a force in the centripetal direction, which is always in contact with the negative gradient curves F to G on the inner periphery of the cam ring and enters the groove 16 of the rotor 13 in the second closed section 23B. That is, the vane 17 is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring. As a result, generation of a large pressure pulsation due to the separation of the vane 17 can be prevented. .
[0059]
Second Embodiment (FIGS. 5 and 9 to 13)
The details of the embodiments described in claims 5 to 8 and the cam ring-shaped vane separation preventing action of the present invention are as follows.
[0060]
The inner peripheral shape of the cam ring 22 was set as follows (1) to (5). In FIG. 5, O <b> 1 is the center position of the rotor 13, O <b> 2 is the center position of the inner peripheral perfect circle part of the cam ring 22, and E is the maximum eccentric amount of the cam ring 22.
[0061]
(1) In the rotational direction of the rotor 13 under the maximum eccentric state of the cam ring 22, the cam ring 22 is in a suction section where the vane is located at the suction port 24 and a discharge section where the vane is located at the discharge port 27. Is formed by perfect circular curves F to G, K to A (center O2).
[0062]
(2) In the first confinement section 23A at the bottom dead center where the space between the adjacent vanes 17 and 17 is sandwiched between the suction section and the discharge section and is not connected to the suction port 24 and the discharge port 27, the cam ring The inner peripheral shape of 22 is always in contact with the tip of the vane 17 regardless of the amount of eccentricity E, so that the vane 17 can be pushed in the centripetal direction along the groove 16 of the rotor 13. Two curves that can provide a centripetal motion in which the protrusion radius (dynamic radius) of the rotor 13 with respect to the center O1 gradually decreases as the rotational angle of the rotor 13 increases (decreasing the radius of curvature where the radius of curvature decreases along the rotational direction of the rotor 13). Curve) (hereinafter referred to as a negative slope curve) B to C and D to E, and secondary higher-order curves C to D (transient curves) that smoothly connect negative slope curves B to C and D to E Constitute
[0063]
In order to impart centripetal motion to the vane even when the amount of eccentricity E decreases in the high speed rotation region, the negative gradient curves D to E constituting the second half of the first confinement section 23A are negative gradient curves constituting the first half. The gradient is made larger than B to C.
[0064]
(3) In the connecting portion connected to the suction section and the first confinement section 23A, the inner peripheral shape of the cam ring 22 is expressed by the negative gradient curves B to C of the first confinement section 23A and the perfect circular curves K to A of the suction section. Are composed of higher-order curves A to B (transient curves) of the second and higher order. Further, the first and second higher-order curves E to F (transient curves) that smoothly connect the negative gradient curves D to E of the first confinement section 23A and the perfect circular curves F to G of the suction section.
[0065]
(4) In the second confinement section 23B at the top dead center where the space between the adjacent vanes 17 and 17 is sandwiched between the suction section and the discharge section and does not connect to the suction port 24 and the discharge port 27, the cam ring The inner circumferential shape of 22 is always in contact with the tip of the vane 17 regardless of the amount of eccentricity E, so that the vane 17 can be pushed in the centripetal direction along the groove 16 of the rotor 13. Two negative gradient curves G to H and I to J (curvature along the direction of rotation of the rotor 13) that can give a centripetal motion in which the radius of motion of the rotor 13 with respect to the center O1 gradually decreases as the rotation angle of the rotor 13 increases. A radius-of-curvature decreasing curve) and secondary higher-order curves H to I (transient curves) connecting these negative gradient curves G to H and I to J smoothly.
[0066]
Note that the negative gradient curves G to H constituting the first half of the second confinement section 23B may be perfect circle curves, and the gradients of the negative gradient curves I to J constituting the second half may be slight.
[0067]
(5) At the connection portion located at the end of the suction section and connected to the second confinement section 23B, the inner peripheral shape of the cam ring 22 is changed to the negative gradient curves I to J of the second confinement section 23B and the true value of the suction section. A plurality of second-order or higher-order curves J to K (transient curves) that smoothly connect the circular curves K to A are used. However, since this higher-order curve is outside the second confinement section 23B, the load is not applied to the vane, and even if the gradient is positive, the vane is not separated.
[0068]
The solid lines in FIGS. 9 to 11 indicate that the tip of the vane 17 is kept in contact with the inner periphery of the cam ring 22 at each angular position in the circumferential direction of the rotor 13 when the cam ring 22 is fully eccentric (when the pump 10 rotates at a low speed). , The size of the protrusion radius (dynamic radius) of the vane 17 with respect to the center O1 of the rotor 13 is shown, A to B are high-order curves, B to C are negative gradient curves, C to D are high-order curves, D to E Is a negative gradient curve, E to F are high-order curves, F to G are perfect circle curves, G to H are negative gradient curves, HI are high-order curves, I to J are negative gradient curves, and J to K are plural. The higher order curves K to A are perfect circle curves. In addition, the broken line of FIGS. 9-11 shows the case of the cam ring which comprised the perimeter by the perfect circle curve.
[0069]
Therefore, according to the second embodiment, there are the following actions (FIGS. 12 to 14).
(Operation in the first confinement section 23A)
(1) When the vane 17 is in the first confining section 23A, the vane 17 has a discharge port 27 side high pressure on the front surface and a low pressure suction port 24 side on the back surface. An eccentric load is received in the circumferential direction, and the base is accommodated in the groove 16 of the rotor 13 to be caught. However, the vane 17 performs a centripetal motion that enters the groove 16 of the rotor 13 while always in contact with the negative gradient curves B to C and D to E and the higher order curves C to D of the inner periphery of the cam ring in the first closed section 23A. Is granted. That is, the vane 17 is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring. As a result, a large pressure pulsation caused by the separation of the vane generated in the perfect circle cam ring. Can be prevented, and vibration and noise caused by this can be significantly reduced.
[0070]
(2) The negative gradient curves B to C and D to E of the first confining section 23A and the perfect circular curves K to A and F to G of the discharge section or the suction section are represented by higher order curves A to B and E to F. By connecting smoothly, the speed change of the vane in the connecting section becomes gentle (acceleration becomes small), and the vibration force due to the inertial force of the vane can be reduced. Noise can be prevented.
[0071]
(3) Different slopes of the two negative gradient curves B to C and D to E constituting the inner peripheral shape of the cam ring in the first closed section 23A (specifically, the first closed section 23A) The first half of the pump 10 is composed of negative gradient curves B to C with a small gradient, and the second half is composed of negative gradient curves D to E with a large gradient), so that the pump 10 rotates at a low speed (when the cam ring is fully eccentric) to a high speed rotation. It is possible to prevent the vane 17 from separating in the first closed section 23A in a wide operating range (at the time of minimum eccentricity) (a wide eccentric range of the cam ring). As a result, pressure pulsation and pump vibration and noise caused thereby can be reduced. It can be significantly reduced.
[0072]
FIG. 12 shows the vane separation preventing effect of the cam ring having the negative slope curve of the present invention in the first confinement section 23A. FIG. 12 (A) shows when the pump 10 rotates at a low speed (when the cam ring 22 is fully eccentric). The vane 17 indicates that no separation occurs in the first half to the second half of the first confinement section 23A, and (B) shows that the cam ring moves even when the pump 10 rotates at high speed (when the cam ring 22 is at the minimum eccentricity). The figure shows that the radius gradually decreases with the rotation of the rotor and maintains the shape, and no separation occurs in the entire first half to second half of the first closed section 23A.
[0073]
(Operation in the second confinement section 23B)
(1) When the vane 17 is in the second closing section 23B, the high pressure on the discharge port 27 side acts on the back surface of the vane 17 and the low pressure on the suction port 24 side acts on the front surface. An eccentric load is received in the circumferential direction, and the base is accommodated in the groove 16 of the rotor 13 and is caught. However, the vane 17 is applied with a force in the centripetal direction, which is always in contact with the negative gradient curves G to H and I to J of the inner periphery of the cam ring and enters the groove 16 of the rotor 13 in the second closed section 23B. That is, the vane 17 is always pushed in the centripetal direction by contact with the inner periphery of the cam ring, and is not separated from the inner periphery of the cam ring. As a result, generation of a large pressure pulsation due to the separation of the vane 17 can be prevented. .
[0074]
(2) Different slopes of the two negative gradient curves G to H and I to J constituting the inner peripheral shape of the cam ring in the second confinement section 23B (specifically, for example, the second confinement section 23B) The first half is composed of a perfect circular curve or negative gradient curves G to H close thereto, and the second half is composed of negative gradient curves I to J having relatively small slopes), so that the pump 10 can rotate at a low speed (the maximum of the cam ring). Since the vane 17 can be prevented from separating in the second confinement section 23B over a wide operating range (at the time of the minimum eccentricity of the cam ring) (at the time of eccentricity) to the high speed rotation (at the time of the minimum eccentricity of the cam ring), the pressure pulsation is significantly reduced. it can.
[0075]
FIG. 13 shows the effect of preventing the vane 17 from separating in the second closing section 23B. FIG. 13A shows that the vane 17 is in the second closing section 23B when the pump 10 rotates at a low speed (when the cam ring 22 is fully eccentric). (B) shows that even when the pump 10 rotates at high speed (when the cam ring 22 is at the minimum eccentricity), the cam ring gradually reduces the moving radius of the vane with the rotation of the rotor. This indicates that the shape to be maintained is maintained, and no separation occurs in the entire area from the first half to the second half of the second confinement section 23B.
[0076]
In FIGS. 12 and 13, the solid line indicates the relationship between the rotor rotation angle and the dynamic radius when the cam ring 22 of the present embodiment is used, and the broken line indicates the rotor rotation angle and the dynamic range when the perfect circular curve cam ring 22 is used. It shows the relationship of the radius.
[0077]
Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. However, it is included in the present invention.
[0078]
【The invention's effect】
As described above, according to the present invention, in the closed section where the vane receives an eccentric load (the first closed section and the second closed section), the tip of the vane is always in the cam ring regardless of the eccentric amount of the cam ring. The vanes are not separated because they are pressed against the circumference, and the pressure pulsation induced by intermittent leakage from the vane tip clearance and the vibration and noise associated with it are greatly increased over the wide operating range of the variable displacement vane pump. Can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a variable displacement pump.
2 is a cross-sectional view taken along line II-II in FIG.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a cross-sectional view taken along line IV-IV in FIG.
FIG. 5 is a schematic view showing a cam ring.
FIG. 6 is a diagram showing changes in the vane radius (dynamic radius) over the entire circumference of the cam ring according to the first embodiment;
FIG. 7 is an enlarged diagram of the first confinement section in the dynamic radius of the first embodiment.
FIG. 8 is an enlarged diagram of a second confinement section in the dynamic radius of the first embodiment.
FIG. 9 is a diagram showing changes in the vane radius (dynamic radius) over the entire circumference of the cam ring according to the second embodiment;
FIG. 10 is an enlarged diagram of the first confinement section in the moving radius of the second embodiment.
FIG. 11 is an enlarged diagram of a second confinement section in the dynamic radius of the second embodiment.
FIG. 12 is a diagram showing a vane separation preventing effect during low-speed rotation and high-speed rotation in the first closed section of the second embodiment.
FIG. 13 is a diagram showing a vane separation preventing effect during low-speed rotation and high-speed rotation in the second confinement section of the second embodiment.
FIG. 14 is a schematic diagram showing a catching phenomenon of a vane in the first confinement section.
FIG. 15 is a diagram showing vane separation states during low-speed rotation and high-speed rotation in a first closed section of a conventional cam ring.
FIG. 16 is a diagram showing vane separation states during low speed rotation and high speed rotation in a second closed section of a conventional cam ring.
FIG. 17 is a schematic diagram showing the eccentric state of the cam ring during low-speed rotation and high-speed rotation.
[Explanation of symbols]
10 Variable displacement pump
11 Pump casing
13 Rotor
16 groove
17 Vane
22 Cam Ring
23 Pump room
23A First confinement section
23B Second confinement section
24 Suction port
27 Discharge port
81A Negative slope curve
81B, 81C Higher order curve

Claims (8)

A pump casing;
A perfectly circular rotor disposed in the pump casing and driven to rotate;
A cam ring which is disposed around the rotor and forms a pump chamber between the outer periphery of the rotor and can be eccentric with respect to the rotor;
A suction port disposed in the pump casing and sucking hydraulic oil into the pump chamber;
A discharge port disposed in the pump casing for discharging hydraulic oil from the pump chamber;
A plurality of vanes which are accommodated in the grooves of the rotor and protrude so as to be movable in the radial direction, and whose tips contact the inner periphery of the cam ring;
The hydraulic oil sucked from the suction port is sandwiched in the space between the adjacent vanes, and this hydraulic oil is transported by the rotation of the rotor and discharged from the discharge port.
In the variable displacement pump that increases the discharge amount of hydraulic oil by increasing the eccentric amount of the cam ring with respect to the rotor,
The inner circumference of the cam ring is the shape of the suction section that sucks hydraulic oil from the suction port, the shape of the first confinement section at the bottom dead center where the hydraulic oil sucked from the suction port is discharged and pre-compressed to the port, and discharged It is composed of the shape of the discharge section that discharges the hydraulic oil from the port, the shape of the second closed section that transfers the hydraulic oil sandwiched in the space between adjacent vanes at the top dead center to the suction port,
The inner circumference of the cam ring in the suction section and the discharge section is composed of a perfect circle curve and a transient curve,
The inner circumference of the cam ring in the closed section has a radius of curvature along the direction of rotation of the rotor so that the moving radius of the vane always decreases with an increase in the rotation angle of the rotor regardless of the eccentric amount of the cam ring. The variable displacement vane pump is characterized by comprising a negative gradient curve that decreases with time. In the first confinement section, the cam ring has a radius of curvature so that the moving radius of the vane always decreases with an increase in the rotation angle of the rotor regardless of the amount of eccentricity of the cam ring. The variable displacement pump according to claim 1, wherein the variable displacement pump is constituted by a negative slope curve that decreases along the line. In the second confining section, the cam ring has a radius of curvature so that the moving radius of the vane is always decreased with respect to an increase in the rotation angle of the rotor regardless of the amount of eccentricity of the cam ring. The variable displacement pump according to claim 1, wherein the variable displacement pump is constituted by a negative slope curve that decreases along the line. The shape of the cam ring is connected to both ends of the suction section or the discharge section and the first confinement section or the second confinement section. Alternatively, the variable displacement vane pump according to any one of claims 1 to 3, wherein a transient curve smoothly connected to the negative gradient curve of the second confinement section is a high-order curve. A pump casing;
A perfectly circular rotor disposed in the pump casing and driven to rotate;
A cam ring which is disposed around the rotor and forms a pump chamber between the outer periphery of the rotor and can be eccentric with respect to the rotor;
A suction port disposed in the pump casing and sucking hydraulic oil into the pump chamber;
A discharge port disposed in the pump casing for discharging hydraulic oil from the pump chamber;
A plurality of vanes which are accommodated in the grooves of the rotor and protrude so as to be movable in the radial direction, and whose tips contact the inner periphery of the cam ring;
The hydraulic oil sucked from the suction port is sandwiched in the space between the adjacent vanes, and this hydraulic oil is transported by the rotation of the rotor and discharged from the discharge port.
In the variable displacement pump that increases the discharge amount of hydraulic oil by increasing the eccentric amount of the cam ring with respect to the rotor,
The inner circumference of the cam ring is the shape of the suction section that sucks hydraulic oil from the suction port, the shape of the first confinement section at the bottom dead center where the hydraulic oil sucked from the suction port is discharged and pre-compressed to the port, and the discharge The shape of the discharge section for discharging the hydraulic oil from the suction port, the second closed section for transferring the hydraulic oil sandwiched in the space between the adjacent vanes at the top dead center to the suction port,
The inner circumference of the cam ring in the suction section and the discharge section is composed of a perfect circle curve and a transient curve,
The inner circumference of the cam ring in the confined space has a radius of curvature along the direction of rotation of the rotor so that the moving radius of the vane always decreases with an increase in the rotation angle of the rotor regardless of the amount of eccentricity of the cam ring. A variable displacement vane pump characterized by comprising a plurality of negative gradient curves that decrease in number. In the first confinement section, the cam ring has a radius of curvature so that the moving radius of the vane always decreases with an increase in the rotation angle of the rotor regardless of the amount of eccentricity of the cam ring. The variable displacement pump according to claim 5, comprising a plurality of negative gradient curves decreasing along the axis. In the second confining section, the cam ring has a radius of curvature so that the moving radius of the vane is always decreased with respect to an increase in the rotation angle of the rotor regardless of the amount of eccentricity of the cam ring. The variable displacement pump according to claim 5, comprising a plurality of negative gradient curves decreasing along the axis. The shape of the cam ring is connected to both ends of the suction section or the discharge section and the first confinement section or the second confinement section. Alternatively, the variable displacement vane pump according to any one of claims 5 to 7, wherein a transient curve smoothly connected to the negative gradient curve of the second confinement section is a high-order curve.

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