JP2014181612A - Pump unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump unit capable of suppressing galling due to a rotor.SOLUTION: A drive shaft is formed in the axial direction thereof so that the flexural rigidity of the drive shaft in a second region is lower than the flexural rigidity of the drive shaft in a first region when the first region is a predetermined range in the axial direction including a midpoint of a rotor, and the second region is a predetermined range in the axial direction which is adjacent to another side in the axial direction of the first region and includes an end portion of a second bearing close to the rotor.

Description

  The present invention relates to a pump device.

  As this type of technique, a technique described in Patent Document 1 below is disclosed. Patent Document 1 discloses a variable displacement vane pump in which an approximately half-circumferential region is a suction region and a approximately half-circular region is a discharge region with respect to the rotation direction of the rotor.

JP 2011-132812 JP

In the variable displacement vane pump described in Patent Document 1, a force acts on the rotor from the discharge region toward the suction region. Since the drive shaft is supported outside the both ends of the rotor in the front housing and the rear housing, bending deformation occurs at the junction of the drive shaft with the rotor.
In addition, since there is a pressure plate on the front housing side in the axial direction of the drive shaft, the distance between the center portion of the rotor and the shaft support portion of the drive shaft on the front housing side is the distance between the center portion of the rotor and the drive shaft support portion on the rear housing side. And longer than the distance. For this reason, the apex of the bending deformation that occurs in the drive shaft is on the front housing side, which causes the rotor to tilt, and the rotor may come into contact with the side surface of the pressure plate or the rear housing, which may cause galling.
The present invention has been focused on the above problems, and an object of the present invention is to provide a pump device that can suppress galling by the rotor.

  In order to achieve the above object, in the pump device of the present invention, the drive shaft has a predetermined axial range including the intermediate point of the rotor in the axial direction as the first region, and is adjacent to the other axial side of the first region. When the predetermined range in the axial direction including the end of the second bearing close to the rotor is the second region, the bending rigidity of the drive shaft in the second region is smaller than the bending rigidity of the drive shaft in the first region. Formed.

  Accordingly, it is possible to suppress the contact of the rotor piece and to suppress galling.

1 is an axial sectional view of a variable displacement vane pump according to Embodiment 1. FIG. 1 is a radial sectional view of a variable displacement vane pump of Example 1. FIG. FIG. 3 is an enlarged view of a drive shaft portion according to the first embodiment. FIG. 3 is an enlarged view of a drive shaft portion according to the first embodiment. FIG. 6 is an enlarged view of a drive shaft portion of Embodiment 2.

[Example 1]
[Outline of vane pump]
1 is an axial sectional view of the variable displacement vane pump 1 according to the first embodiment (II sectional view of FIG. 2), and FIG. 2 is a radial sectional view of the variable displacement vane pump 1 (II-II sectional view of FIG. 1). It is. FIG. 2 shows the case where the cam ring 4 is located in the most negative y-axis direction (maximum eccentricity).
The variable displacement vane pump 1 according to the first embodiment supplies hydraulic fluid to a power steering device mounted on a vehicle, and a drive shaft 2 is connected to a pulley that is driven via a belt or the like to an engine not shown. ing. The cross-sectional view of FIG. 2 schematically shows the oil passage configuration and the like in order to simplify the description of the pump function. The axial direction of the drive shaft 2 is the x-axis, and the direction in which the drive shaft is inserted into the pump body 10 is the positive direction. In addition, the axial direction of the cam spring 201 (see FIG. 2) that restricts the swinging of the cam ring 4 and the direction in which the cam ring 4 is urged is the negative direction of the y axis, and the axis that is orthogonal to the x and y axes, The IN side is the z-axis positive direction. The vane pump according to the first embodiment boosts the working fluid sucked from the reservoir tank to a necessary pressure and supplies a necessary flow rate to the power steering apparatus.

  The variable displacement vane pump 1 includes a drive shaft 2, a rotor 3, a cam ring 4, an adapter ring 5, and a pump body 10. The drive shaft 2 is rotatably supported by the pump body 10. A pulley is connected to the end of the drive shaft 2 on the x-axis negative direction side. A serration 24 is formed in a portion of the drive shaft 2 where the rotor 3 is provided. A serration 34 is also formed on the inner peripheral surface of the rotor 3. By fitting the serration 24 of the drive shaft 2 and the serration 34 of the rotor 3, the rotational driving force of the drive shaft 2 is transmitted to the rotor 3. The axial length of the serration 24 of the drive shaft 2 is shorter than the axial length of the rotor 3. A plurality of slits 31 that are axial grooves are formed radially on the outer periphery of the rotor 3. A plate-like vane 32 having substantially the same length in the x-axis direction as the rotor 3 is inserted into each slit 31 so as to be able to advance and retract in the radial direction. Further, a back pressure chamber 33 is provided at the inner diameter side end of each slit 31, and hydraulic fluid is supplied to bias the vane 32 radially outward.

  The pump body 10 is formed from a front body 11 and a rear body 12. The front body 11 has a bottomed cup shape that opens in the positive x-axis direction, and a cylindrical pump element accommodating portion 112 is formed on the inner peripheral portion of the front body 11. The x-axis negative direction side of the pump element accommodating portion 112 is closed by the bottom portion 111. A disc-shaped pressure plate 6 is accommodated on the bottom 111. The front body 11 and the rear body 12 are fastened and fixed by a plurality of bolts. The adapter ring 5, the cam ring 4, and the rotor 3 are accommodated in the pump element accommodating portion 112 on the positive side of the pressure plate 6 in the x-axis direction. The rear body 12 is in liquid-tight contact with the adapter ring 5, the cam ring 4, and the rotor 3 from the x-axis positive direction side, and the adapter ring 5, the cam ring 4, and the rotor 3 are held between the pressure plate 6 and the rear body 12.

  The adapter ring 5 is an annular member that is provided in the pump element accommodating portion 112 that is a cylindrical portion and in which the cam ring accommodating portion 54 is formed. The shape of the adapter ring 5 is not limited to the ring shape, and may be formed in a C shape as long as it has at least an arc-shaped portion so that an accommodation space is formed inside. A radial through hole 51 is provided at the end of the adapter ring 5 in the positive y-axis direction. Further, a plug member insertion hole 114 is provided at the end of the front body 11 in the positive y-axis direction, and a bottomed cup-shaped plug member 73 is screwed to ensure liquid-tightness between the front body 11 and the outside. A cam spring 201 is inserted into the inner periphery of the plug member 73 so as to be expandable and contractible in the y-axis direction, penetrates the radial through hole 51 of the adapter ring 5 and comes into contact with the cam ring 4, and is biased in the negative y-axis direction. . The cam spring 201 urges the cam ring 4 in the direction in which the swing amount becomes maximum, and stabilizes the discharge amount (cam ring swing position) at the time of pump start when the pressure is not stable.

The cam ring 4 is accommodated in the cam ring accommodating portion 54 of the adapter ring 5. The tip of the vane 32 rotates while contacting the inner peripheral surface (cam ring inner peripheral surface 41) of the cam ring 4, and a plurality of pump chambers 13 are formed by the cam ring inner peripheral surface 41, the rotor 3 and the vane 32. The cam ring 4 is provided in the cam ring housing portion 54 of the adapter ring 5 so as to be movable with respect to the drive shaft 2.
A pin 40 a is provided between the adapter ring 5 and the cam ring 4. This pin 40a prevents the adapter ring 5 from rotating in the front body 11 when the pump is driven.

A seal member 50 is provided at the z-axis positive end portion of the cam ring housing portion 54, a support surface N is formed at the z-axis negative direction end portion, and a support plate 40 is provided at the support surface N. The cam ring 4 is provided on the support plate 40 so as to be swingable in the y-axis direction. The support plate 40 and the seal member 50 separate the first fluid pressure chamber A1 and the second fluid pressure chamber A2 between the cam ring 4 and the adapter ring 5. The first fluid pressure chamber A1 is provided in the cam ring housing portion 54 and on the outer peripheral side of the cam ring 4, and the internal volume decreases when the cam ring 4 moves in the direction in which the volumes of the plurality of pump chambers 13 increase. Is formed. The second fluid pressure chamber A2 is provided in the cam ring housing portion 54 and on the outer peripheral side of the cam ring 4, and the internal volume increases when the cam ring 4 moves in the direction in which the volumes of the plurality of pump chambers 13 increase. Is formed.
A through hole 52 is provided on the z-axis positive direction side of the adapter ring 5 and on the y-axis negative direction side of the seal member 50. The through holes 52 communicate with the spool 70 via control pressure oil passages 113 provided in the front body 11, respectively, and connect the first fluid pressure chamber A1 and the spool 70 on the y axis negative direction side.

[Configuration of front body]
The front body 11 is formed with a shaft support portion 117 that supports the drive shaft 2. The shaft support 117 is formed through the bottom 111. A cylindrical first bush 14 (sliding bearing) is provided between the shaft support 117 and the drive shaft 2. An oil seal 15 is provided at the end of the shaft support 117 on the pulley 9 side to ensure liquid tightness in the pump. On the positive z-axis direction side of the front body 11, there is a control valve housing hole 116 for housing a spool 70, which is a pressure control means for controlling the amount of eccentricity of the cam ring 4 by controlling the pressure in the first fluid pressure chamber A1. The control valve suction oil passage 115 for introducing the hydraulic fluid from the suction passage IN into the spool 70 and the control pressure oil passage 113 for discharging the control pressure into the first fluid pressure chamber A1.
Also, the bottom 111 has a suction groove 111b formed in a position facing the second suction port 62 of the pressure plate 6 described later, and a discharge formed in a position facing the second discharge port 63. It has a groove 111a, a discharge pressure introduction groove 111c that faces the side surface in the negative x-axis direction of the suction side back pressure groove 64, and a discharge passage 20 that is connected to the discharge groove 111a and sends hydraulic fluid to the power steering device. A suction pressure acts on the suction groove 111b, and a discharge pressure acts on the discharge groove 111a and the discharge pressure introduction groove 111c. A lubricating oil path 118 is formed in the suction groove 111b obliquely with respect to the x axis, and hydraulic fluid is supplied to lubricate between the first bush 14 and the drive shaft 2.

[Configuration of pressure plate]
The pressure plate 6 is provided in the pump element accommodating portion 112 that is a cylindrical portion, and is disposed between the adapter ring 5 and the bottom portion 111. The pressure plate 6 is a contact surface 61 that contacts an end surface on one side of the adapter ring 5 in the axial direction, and a hole formed so that the drive shaft 2 can pass therethrough. The pressure plate 6 moves relative to the drive shaft 2 in the axial direction. A through-hole 66 is formed so as to be possible.
On the x contact surface 61 of the pressure plate 6, a second suction port 62 arranged in an arc shape on the z-axis positive direction side, a second discharge port 63 arranged in an arc shape on the z-axis negative direction side, A suction-side back pressure groove 64 and a discharge-side back pressure groove 65 for introducing discharge pressure into the back pressure chamber 33 are formed. The second suction port 62 is disposed so as to face one end surface of the cam ring 4 in the axial direction, and is formed so as to open to a suction region where the volumes of the plurality of pump chambers 13 increase as the drive shaft 2 rotates. .
The pressure plate 6 is biased toward the adapter ring 5 when the discharge pressures of the discharge groove 111a and the discharge pressure introduction groove 111c act on the side surface 67 in the x-axis negative direction.

[Configuration of rear body]
In the rear body 12, a suction passage 12a is formed in the z-axis direction for introducing the working fluid from a reservoir tank that stores the working fluid to the first suction port 122. An oil passage 12d for supplying hydraulic fluid to the spool 70 is formed on the positive side of the suction passage 12a in the z-axis direction. A bottomed shaft support portion 12c that supports the drive shaft 2 is formed at a substantially central portion of the rear body 12. A cylindrical second bush 16 (sliding bearing) is provided between the shaft support 12c and the drive shaft 2. A lubricating oil passage 12b communicating with the shaft support portion 12c is formed at the lower end of the suction passage 12a, and hydraulic fluid is supplied to lubricate between the second bush 16 and the drive shaft 2.
The rear body 12 has a pump-forming surface 120 that is raised in a circular shape on the negative side in the x-axis direction. The pump forming surface 120 is disposed so as to face the side surface of the cam ring 4 in the positive x-axis direction, and a first suction port 122 is formed so as to open to the suction region. Further, the first discharge port 123 is formed so as to face the side surface of the cam ring 4 on the x-axis direction side and open to the discharge region. Further, the suction side back pressure groove 124 and the discharge side back pressure groove 125 for introducing the discharge pressure into the back pressure chamber 33 are formed on the pump forming surface 120.

(Configuration of control unit)
The control unit of the variable displacement vane pump 1 includes a first fluid pressure chamber A1, a second fluid pressure chamber A2, a control valve 7, and a discharge passage 20.
The discharge passage 20 is a passage for hydraulic fluid that connects each part in the pump body 10. The front body 11 is formed with a substantially cylindrical control valve accommodating hole 116 extending in the y-axis direction, and the control valve 7 is accommodated in the control valve accommodating hole 116.
The control valve 7 switches the supply of the hydraulic fluid to the first fluid pressure chamber A1 by displacing the position of the spool 70. In the state of FIG. 2, the control pressure oil passage 113 and a low pressure chamber 116b described later are in communication with each other, and suction pressure is applied to the first fluid pressure chamber A1.
A valve spring 71 is installed in a compressed state on the positive side of the spool 70 in the y-axis positive direction, and constantly urges the spool 70 in the negative direction of the y-axis. A lid member 72 that closes the opening of the control valve housing hole 116 is screwed onto the negative side of the spool 70 in the y-axis negative direction.

The spool 70 is formed with a first small-diameter portion 70a, a first land portion 70b, a second small-diameter portion 70c, and a second land portion 70d sequentially from the y-axis negative direction side. The outer diameters of the first land portion 70b and the second land portion 70d are formed to be substantially the same as the inner diameter of the control valve housing hole 116, and the outer diameters of the first small diameter portion 70a and the second small diameter portion 70c are controlled. The valve housing hole 116 is formed to have a smaller diameter than the inner diameter. In the control valve accommodation hole 116, a high pressure chamber 116a is formed by a space surrounded by the inner circumference of the control valve accommodation hole 116, the outer circumference of the first small diameter portion 70a, the lid member 72, and the first land portion 70b. Further, a low pressure chamber 116b is formed by a space surrounded by the inner periphery of the control valve accommodating hole 116, the outer periphery of the second small diameter portion 70c, the first land portion 70b, and the second land portion 70d. An intermediate pressure chamber 116c is formed by the inner periphery of the control valve housing hole 116, the end surface on the y-axis positive direction side, and the second land portion 70d.
Both the high pressure chamber 116a and the intermediate pressure chamber 116c communicate with the discharge passage 20. The discharge passage 20 communicates with the discharge groove 111a and branches into a passage 21 and a passage 22. The passage 22 is connected to the high pressure chamber 116a, and the passage 21 is connected to the intermediate pressure chamber 116c. A metering orifice 23 is provided in the middle of the passage 21. As the discharge flow rate of the variable displacement vane pump 1 increases due to the metering orifice 23, the differential pressure across the metering orifice 23 increases. That is, the higher the discharge pressure, the lower the pressure in the intermediate pressure chamber 116c with respect to the pressure in the high pressure chamber 116a.

  In the spool 70, a relief valve housing hole 70e that is open on the positive side in the y-axis is formed. The relief valve 8 is accommodated in the relief valve accommodation hole 70e. The relief valve 8 communicates the intermediate pressure chamber 116c and the low pressure chamber 116b when the pressure in the intermediate pressure chamber 116c becomes too high. The relief valve 8 is provided with a valve spring 80, a spring holding member 81, a ball plug 82, and a seat member 83 in this order from the y-axis negative direction side. The seat member 83 is formed with a through hole 83a penetrating in the axial direction, and is press-fitted into the relief valve accommodating hole 70e. The valve spring 80 is provided in a compressed state between the bottom surface of the relief valve housing hole 70e on the negative side in the y-axis and the spring holding member 81, and the ball plug 82 is connected to the seat member 83 via the spring holding member 81. Energized in the direction. The spool 70 is formed with a through hole 70f penetrating the relief valve accommodating hole 70e and the outer periphery of the second small diameter portion 70c in the vicinity of the ball plug 82. That is, the negative y-axis direction side of the relief valve housing hole 70e from the ball plug 82 communicates with the low pressure chamber 116b.

[Configuration of drive shaft]
FIG. 3 is an enlarged view of the vicinity of the drive shaft 2. Of the drive shaft 2, a region where the serrations 24 are formed is a first region D1, and a region adjacent to the first region D1 and including the end of the second bushing 16 on the x-axis negative direction side is a second region D2. The serration 24 is formed in the central portion of the rotor 3 in the axial direction as shown in FIG. A load in the rotational direction is received by the serration 24 portion of the drive shaft 2, and a load in the radial direction is also received by the serration 24 portion.
A hollow portion 25 is formed in the axial center portion of the end portion of the drive shaft 2 in the negative x-axis direction. The x-axis positive direction side end of the hollow portion 25 is open, and the x-axis positive direction side end is closer to the x-axis negative direction side than the x-axis negative direction side end of the second bush 16 (second region D2). It extends to. In other words, the x-axis positive direction side of the hollow portion 25 is formed in a range where the second bush 16 is provided, and the x-axis negative direction side end portion of the hollow portion 25 is formed in the second region D2.
Accordingly, the bending rigidity of the drive shaft 2 is smaller in the second region D2 where the hollow portion 25 is formed than in the first region D1 where the hollow portion 25 is not formed. Further, serrations 24 are formed in the first region D1, and the bending rigidity is greater than that of other portions of the drive shaft 2 that are densely formed with the same diameter.

[Action]
(Supply of hydraulic fluid to the first and second fluid pressure chambers)
Next, the effect | action regarding supply of a hydraulic fluid is demonstrated.
The passage 21 is connected to the high pressure chamber 116a of the control valve accommodation hole 116, and the passage 22 is connected to the intermediate pressure chamber 116c. The differential pressure across the metering orifice 23 increases as the discharge flow rate of the variable displacement vane pump 1 increases by the metering orifice 23 provided in the middle of the passage 22. That is, as the discharge flow rate increases, the pressure in the intermediate pressure chamber 116c becomes lower than the pressure in the high pressure chamber 116a. The position of the spool 70 is controlled by the differential pressure at this time and the urging force of the valve spring 71 provided on the positive side of the spool 70 in the y-axis direction, thereby generating a control pressure.

  Specifically, when the discharge flow rate of the variable displacement vane pump 1 is small and the differential pressure across the metering orifice 23 is small, the differential pressure between the pressure in the high pressure chamber 116a and the pressure in the intermediate pressure chamber 116c is small. Therefore, the y-axis positive biasing force received from the pressure in the high-pressure chamber 116a is smaller than the pressure in the intermediate pressure chamber 116c and the y-axis negative biasing force received from the valve spring 71 by the spool 70. The y-axis is moving in the negative direction (the spool 70 is located at the position shown in FIG. 2). At this time, the first fluid passage A1 communicates with the low pressure chamber 116b, and a suction pressure is introduced as a control pressure.

As the discharge flow rate of the variable displacement vane pump 1 increases, the differential pressure across the metering orifice 23 increases as the discharge flow rate increases. Along with this, when the y-axis positive biasing force received from the pressure in the high-pressure chamber 116a becomes larger than the pressure in the intermediate pressure chamber 116c and the biasing force in the negative y-axis direction received from the valve spring 71 by the spool 70, The spool 70 starts to move in the positive y-axis direction. When the spool 70 moves to the y-axis positive direction side, the opening area of the control pressure oil passage 113 opened to the low pressure chamber 116b by the first land portion 70b gradually decreases, and conversely, the control pressure oil passage opened to the high pressure chamber 116a. The opening area of 113 gradually increases. Finally, the communication between the low pressure chamber 116b and the control pressure oil passage 113 is blocked, and the high pressure chamber 116a and the control pressure oil passage 113 are communicated. At this time, a discharge pressure is introduced as a control pressure into the first fluid pressure chamber A1. When the control pressure oil passage 113 is open to both the high pressure chamber 116a and the low pressure chamber 116b, the pressure adjusted to the pressure corresponding to each opening ratio is introduced into the first fluid pressure chamber A1 as the control pressure. Is done.
As described above, the control pressure corresponding to the position of the spool 70 is introduced into the first fluid pressure chamber A1. On the other hand, the second fluid pressure chamber A2 communicates with the second suction port 62 and the first suction port 122, and suction pressure is introduced. Therefore, the suction pressure is always introduced into the second fluid pressure chamber A2, and thereby the variable displacement vane pump 1 is controlled only by the pressure P1 of the first fluid pressure chamber A1. Since the pressure P2 of the second fluid pressure chamber A2 is not controlled and always P2 = suction pressure, the second fluid pressure chamber A2 can obtain a stable pressure, preventing a pressure disturbance, The swing control can be executed.

(Eccentric operation of cam ring)
The positive y-axis biasing force received by the cam ring 4 from the first fluid pressure chamber A1 pressure P1 is greater than the sum of the second fluid pressure chamber A2 pressure P2 and the negative y-axis biasing force received from the cam spring 201. Then, the cam ring 4 moves in the positive y-axis direction while rolling on the support plate 40. By this movement, the volume of the pump chamber 13 on the y-axis positive direction side is increased, and the volume of the pump chamber 13 on the y-axis negative direction side is decreased.
When the volume of the pump chamber 13 on the negative y-axis side decreases, the amount of oil supplied from the suction side to the discharge side per unit time decreases, and the differential pressure between the upstream pressure and downstream pressure of the metering orifice 23 decreases. To do. As a result, the spool 70 is pushed back by the valve spring 71, and the control pressure of the spool 70 is lowered. Therefore, when the pressure P1 of the first fluid pressure chamber A1 also decreases and cannot fully resist the sum of the urging forces in the negative y-axis direction, the cam ring 4 moves in the negative y-axis direction.

  When the urging forces in the positive and negative directions of the y axis become substantially equal, the forces in the y axis direction acting on the cam ring 4 are balanced and the cam ring 4 stops. As a result, when the amount of oil increases, the differential pressure of the metering orifice 23 increases, and the spool 70 pushes the valve spring 71 to increase the valve control pressure. Therefore, contrary to the above, the cam ring 4 moves in the positive y-axis direction. Actually, the cam ring 4 does not cause movement hunting, and the eccentric amount of the cam ring 4 is determined so that the flow rate set by the orifice diameter of the metering orifice 23 and the valve spring 71 is constant.

(Adjusting the bending deformation position of the drive shaft)
In the variable displacement vane pump 1, the pump chamber 13 in the half-circumferential region on the negative z-axis side with respect to the axis of the drive shaft 2 in the pump chamber 13 is in the discharge region, and approximately half-circular on the positive z-axis side. The pump chamber 13 in this area is in the suction area. For this reason, a force acts on the rotor 3 from the discharge region toward the suction region (from the z-axis negative direction side toward the positive direction side). The drive shaft 2 is pivotally supported by the first bush 14 and the second bush 16 on both outer sides in the axial direction of the rotor 3. Therefore, the bending deformation of the drive shaft 2 occurs between the first bush 14 and the second bush 16.
FIG. 4 is an enlarged view of the vicinity of the drive shaft 2. As shown in FIG. 4, the distance L1 from the axial intermediate point of the rotor 3 to the end surface on the positive x-axis side of the first bush 14 is larger than the distance L2 to the end surface on the negative x-axis side of the second bushing 16. long. This is because the pressure plate 6 is interposed between the first bush 14 and the rotor 3.

If the bending rigidity of the drive shaft 2 is uniform, the apex of the bending deformation of the drive shaft 2 is on the negative side of the x axis with respect to the intermediate point of the rotor 3 in the axial direction. Therefore, when the bending deformation occurs in the drive shaft 2, the rotor 3 tilts and may come into contact with the contact surface 61 of the pressure plate 6 or the pump forming surface 120 of the rear body 12, and the rotor 3 may cause galling. There is a risk that the sliding resistance will increase.
Therefore, in Example 1, the drive shaft 2 is formed such that the bending rigidity of the driving shaft 2 in the second region D2 is smaller than the bending rigidity of the driving shaft 2 in the first region. As a result, the second region D2 of the drive shaft 2 is easily bent, and the vertex of the bending deformation of the drive shaft 2 can be brought near the intermediate point in the axial direction of the rotor. Therefore, the inclination of the rotor 3 can be suppressed, the galling to the pressure plate 6 and the rear body 12 can be suppressed, and the sliding resistance of the rotor 3 can be reduced.

In order to reduce the bending rigidity of the second region D2 of the drive shaft 2, the diameter on the x-axis positive direction side including the second region D2 may be reduced. However, if the diameter of the drive shaft 2 is reduced to the extent that the second bush 16 is provided, the sliding area between the second bush 16 and the drive shaft 2 is reduced, and the strength of the second bush 16 cannot be ensured. .
Therefore, in Embodiment 1, the hollow portion 25 is formed in the axial center portion of the second region D2 of the drive shaft 2. Thereby, the bending rigidity of the second region D2 can be reduced without reducing the outer diameter of the drive shaft 2. Therefore, the sliding area between the drive shaft 2 and the second bush 16 can be ensured.

Even if the bending rigidity of the portion of the drive shaft 2 where the second bushing 16 is provided is supported by the second bushing 16, no bending deformation occurs. Therefore, in Example 1, one end portion in the axial direction of the hollow portion 25 is provided on one side in the axial direction from the one end portion in the axial direction of the second bush 16. As a result, the bending rigidity of the second region D2 that is not directly supported by the second bushing 16 can be reduced, and the amount of bending deformation in the second region D2 can be increased.
The portion where the serrations 24 are formed on the drive shaft 2 has higher bending rigidity than the other portions. Therefore, in Example 1, the serration 24 is formed only in the first region D1, but not in the second region. Thereby, the bending rigidity of the second region D2 can be reduced, and the amount of bending deformation in the second region D2 can be increased.

  As described above, the portion of the drive shaft 2 where the second bushing 16 is provided is supported by the second bushing 16 even when the bending rigidity is reduced, so that bending deformation does not occur. For this reason, only the second region D2 needs to reduce the bending rigidity, but it is difficult to provide the hollow portion 25 in the second region D2 that is not the end of the drive shaft 2. Therefore, in the first embodiment, the hollow portion 25 passes through the range where the second bush 16 is provided from the x-axis positive direction end portion of the drive shaft 2 and penetrates to the second region D2. Thereby, the hollow portion 25 can be easily formed in the second region D2 of the drive shaft 2, and the weight of the drive shaft 2 can be reduced.

〔effect〕
The effects of the variable displacement vane pump 1 of the present invention ascertained from Example 1 will be listed below.
(1) A pump body 10 having a pump element accommodating portion 112 therein, a drive shaft 2 rotatably provided in the pump housing 10, a pump element accommodating portion 112 accommodated in the pump element accommodating portion 112, and rotationally driven by the drive shaft 2. The rotor 3 having a plurality of slits 31 on the outer peripheral side, the plurality of vanes 32 provided so as to be able to advance and retreat in each of the plurality of slits 31, and provided movably in the pump element accommodating portion 112, are formed in an annular shape, A cam ring 4 that forms a plurality of pump chambers 13 together with the rotor 3 and the vanes 32, and a first suction port that is provided in the pump body 10 and opens to a region of the plurality of pump chambers 13 that increases in volume as the rotor 3 rotates. 122 (suction port), a suction passage 12a that is provided in the pump body 10 and supplies hydraulic fluid from a reservoir tank that stores the hydraulic fluid to the first suction port 122, and a plurality of pump chambers 13 that are provided in the pump body 10. Low out The first discharge port 123 (discharge port) that opens to the area where the volume decreases with the rotation of 3 and the pump body 10 is provided with the hydraulic fluid discharged from the first discharge port 123 to an external fluid utilization device A discharge passage 20, a control valve 7 (control mechanism) for controlling the eccentric amount of the cam ring 4, and a bearing provided on the pump body 10 for supporting the drive shaft 2, and the rotation shaft of the drive shaft 2 Is the first bush 14 (first bearing) provided on one side of the rotor 3 in the axial direction in the axial direction and the bearing provided on the pump body 10 and supporting the drive shaft 2. A second bushing 16 (second bearing) provided on the other axial side of the rotor 3, the end of the first bushing 14 on the side close to the rotor 3 and the rotor 3 The distance from the axial intermediate point of the second bushing 16 to the end closer to the rotor 3 of the axial end portions of the second bush 16 In the variable displacement vane pump 1 (pump device) provided so as to be larger than the distance from the intermediate point of the rotor 3, the drive shaft 2 has a predetermined axial range including the intermediate point of the rotor 3 in the axial direction. When the second region D2 is defined as the first region D1, the predetermined range in the axial direction including the end of the second bush 16 adjacent to the other axial side of the first region D1 and close to the rotor 3 is defined as the second region D2. The bending rigidity of the drive shaft 2 at is lower than the bending rigidity of the drive shaft 2 in the first region.
Therefore, the inclination of the rotor 3 can be suppressed, the galling to the pressure plate 6 and the rear body 12 can be suppressed, and the sliding resistance of the rotor 3 can be reduced.

(2) A hollow portion 25 in which the axial center portion of the second region of the drive shaft 2 is formed hollow is provided.
Therefore, it is possible to secure a sliding area between the drive shaft 2 and the second bushing 16 while reducing the bending rigidity of the second region D2.
(3) One end in the axial direction of the hollow portion 25 is provided on one side in the axial direction from the one end in the axial direction of the second bush 16.
Therefore, the amount of bending deformation in the second region D2 can be increased.
(4) A serration 24 that meshes with the inner periphery of the rotor 3 is formed on the outer periphery of the drive shaft 2, and the serration 24 is formed in the first region D1 and not in the second region D2.
Therefore, the amount of bending deformation in the second region D2 can be increased.
(5) The hollow portion 25 is formed in a range where the second bush 16 is provided in the axial direction of the drive shaft 2.
Therefore, the hollow portion 25 can be easily formed in the second region D2 of the drive shaft 2, and the weight of the drive shaft 2 can be reduced.

[Example 2]
A variable displacement vane pump 1 according to a second embodiment will be described. In the second embodiment, in order to reduce the bending rigidity of the second region D2 of the drive shaft 2, the small diameter portion 26 is formed instead of the hollow portion 25. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
[Configuration of drive shaft]
FIG. 5 is an enlarged view of the vicinity of the drive shaft 2. In the second region D2 of the drive shaft 2, a small diameter portion 26 having a smaller outer diameter than the other portions was formed. Both end portions in the axial direction of the small diameter portion 26 are formed so as to gradually decrease in diameter toward the center portion.

[Action]
In order to reduce the bending rigidity of the second region D2 of the drive shaft 2, the diameter on the x-axis positive direction side including the second region D2 may be reduced. However, if the diameter of the drive shaft 2 is reduced to the extent that the second bush 16 is provided, the sliding area between the second bush 16 and the drive shaft 2 is reduced, and the strength of the second bush 16 cannot be ensured. .
Therefore, in the second embodiment, the small-diameter portion 26 having a smaller diameter than the outer diameter of the drive shaft in the second region D2 and the first region D1 is formed. Thereby, the bending rigidity of the second region D2 can be reduced without reducing the outer diameter of the drive shaft 2. Therefore, the sliding area between the drive shaft 2 and the second bush 16 can be ensured.
Stress tends to concentrate on the portion of the drive shaft 2 where the bending rigidity is small. Therefore, in Example 2, the small-diameter portion 26 is formed so as to gradually become a small diameter from the axial end portion to the central portion. Thereby, the stress concerning the small diameter portion 26 can be dispersed.
〔effect〕
(6) A small-diameter portion 26 having a smaller diameter than the outer diameter of the drive shaft 2 in the first region D1 is formed in the second region D2.
Therefore, it is possible to secure a sliding area between the drive shaft 2 and the second bushing 16 while reducing the bending rigidity of the second region D2.
(7) The small-diameter portion 26 is formed so as to have a small diameter gradually from the axial end to the center.
Therefore, the stress relating to the small diameter portion 26 can be dispersed, and the overall strength of the drive shaft 2 can be ensured.

[Other Examples]
As described above, the present invention has been described based on the first embodiment and the second embodiment, but the specific configuration of each invention is not limited to the first or second embodiment, and does not depart from the gist of the present invention. Such design changes are included in the present invention.

[Technical thought other than claims]
Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.
(A) In the pump device according to claim 1,
A pump device comprising a hollow portion in which a shaft center portion of the drive shaft on the second bearing side is formed hollow.
Therefore, it is possible to secure a sliding area between the drive shaft and the second bearing while reducing the bending rigidity of the second region.
(B) In the pump device according to claim 1,
2. A pump device according to claim 1, wherein a small-diameter portion smaller in diameter than the outer diameter of the drive shaft in the first region is formed in the second region.
Therefore, it is possible to secure a sliding area between the drive shaft and the second bearing while reducing the bending rigidity of the second region.

(C) In the pump device according to (A) above,
The pump device according to claim 1, wherein one end portion in the axial direction of the hollow portion is provided on one side in the axial direction with respect to one end portion in the axial direction of the second bearing.
Therefore, the amount of bending deformation in the second region can be increased.
(D) In the pump device according to claim 1, (A) or (B) above,
Forming a serration meshing with the inner periphery of the rotor on the outer periphery of the drive shaft;
The pump device according to claim 1, wherein the serration is formed in the first region and not in the second region.
Therefore, the amount of bending deformation in the second region can be increased.

(E) In the pump device according to (B) above,
A pump device characterized in that the diameter is gradually reduced from the axial end to the center of the small diameter portion.
Therefore, the stress relating to the small diameter portion 26 can be dispersed, and the overall strength of the drive shaft can be ensured.
(F) In the pump device according to (A) above,
The pump device according to claim 1, wherein the hollow portion is formed in a range in which the second bearing is provided in an axial direction of the drive shaft.
Therefore, the hollow portion can be easily formed in the second region of the drive shaft, and the weight of the drive shaft can be reduced.

1 Variable displacement vane pump (pump device)
2 Drive shaft
3 Rotor
4 Cam ring
7 Control valve (control mechanism)
10 Pump housing
12a Suction passage
13 Pump room
14 1st bush (1st bearing)
16 2nd bush (2nd bearing)
20 Discharge passage
24 Serration
26 Small diameter part
31 Slit
32 Vane
112 Pump element housing
122 1st inlet (inlet)
123 1st discharge port (discharge port)
A First area
B 2nd area

Claims (1)

A pump housing having a pump element housing therein;
A drive shaft rotatably provided in the pump housing;
A rotor housed in the pump element housing portion, driven to rotate by the drive shaft, and having a plurality of slits on the outer peripheral side;
A plurality of vanes provided so as to freely advance and retract in each of the plurality of slits;
A cam ring that is movably provided in the pump element accommodating portion, is formed in an annular shape, and forms a plurality of pump chambers together with the rotor and the vane;
An inlet provided in the pump housing and opening in a region of the plurality of pump chambers whose volume increases with rotation of the rotor;
An intake passage that is provided in the pump housing and supplies hydraulic fluid from a reservoir tank that stores hydraulic fluid to the inlet;
A discharge port that is provided in the pump housing and opens to a region of the plurality of pump chambers whose volume decreases with rotation of the rotor;
A discharge passage provided in the pump housing and configured to supply hydraulic fluid discharged from the discharge port to an external fluid utilization device;
A control mechanism for controlling the amount of eccentricity of the cam ring;
A bearing provided in the pump housing and pivotally supporting the drive shaft, wherein when the direction of the rotation shaft of the drive shaft is defined as an axial direction, a first shaft provided on one side in the axial direction of the rotor in the axial direction. 1 bearing,
A bearing provided on the pump housing and supporting the drive shaft, the second bearing provided on the other axial side of the rotor;
With
The distance between the axial end of the first bearing near the rotor and the axial intermediate point of the rotor is close to the rotor of the axial end of the second bearing. In the pump device provided to be larger than the distance between the end of the rotor and the intermediate point of the rotor,
In the axial direction, the drive shaft has a predetermined range in the axial direction including an intermediate point of the rotor as a first region, and is adjacent to the other side in the axial direction of the first region to the rotor of the second bearing. Formed so that the bending rigidity of the drive shaft in the second region is smaller than the bending rigidity of the drive shaft in the first region when the predetermined range in the axial direction including the end on the near side is the second region. A pump device characterized by being made.

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