JP2007023991A - Oil pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil pump for always providing smooth rotation of a driving shaft by preventing biased loading between the driving shaft and a bush by deflective deformation. <P>SOLUTION: This oil pump has the driving shaft 8 rotatably stored in a pump body 1, a cam ring 7 forming a plurality of pump rooms 16 on the inner peripheral side together with a rotor 9 and a vane 14, a suction port 18 and a delivery port 20 arranged in a pressure plate 12 arranged on one side in the axial direction of the cam ring, a first fluid pressure chamber 10 and a second fluid pressure chamber 11 formed by defining a space on both sides of the outer peripheral side of the cam ring. While the driving shaft is journaled in one end part 8a to a housing in a driving shaft storage hole 3a of a rear body 3 via a bush 26, a tapered surface 26a such as gradually expanding a diameter toward the rotor from one edge side of the driving shaft is formed on an inner peripheral surface of the bush. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of an oil pump used for a drive source of a power steering of a vehicle.

  As a conventional oil pump, a variable displacement vane pump described in the following Patent Document 1 applied to a power steering device of a vehicle is known.

  This variable displacement vane pump is centered on an adapter ring accommodated in the pump body and a swing fulcrum of a support surface formed on the inner peripheral surface of the adapter ring and formed on the inner peripheral surface of the adapter ring. A cam ring that is swingably provided, a rotor that is provided integrally with a drive shaft that is inserted into the pump body, rotates within the cam ring, and a plurality of slots that are formed along the radial direction on the outer periphery of the rotor. And a plurality of vanes provided so as to be able to protrude and retract in the radial direction from within the slots, and both side plates for sandwiching the cam ring and the rotor from the axial direction.

  Then, the pump discharge amount is controlled by changing the volume of each pump chamber by swinging the cam ring, and the pump ring amount is decreased by swinging the cam ring toward the second fluid pressure chamber at the time of high pump rotation. It is like that.

In addition, by always introducing a low pressure on the suction side into the second fluid pressure chamber, loss of discharge pressure in the second fluid pressure chamber is eliminated, and energy loss is reduced.
JP 2000-265977 A

  Unlike the fixed displacement type, the variable displacement vane pump has one intake port and one discharge port, so the internal pressure of the suction-side pump chamber and the internal pressure of the discharge-side pump chamber are different. Due to the large differential pressure generated in the rotor, the rotor and the drive shaft receive a large pressing force from the discharge port side to the suction port side.

  For this reason, the drive shaft is slightly bent and deformed in a convex shape toward the suction port in the pump body, and the end portion is inclined in the bearing portion. As a result, the outer peripheral surface of the end portion of the drive shaft partially contacts with the inner peripheral surface of the bearing portion, and there is a risk that the surface pressure at this portion increases and hinders smooth rotation of the drive shaft. .

  The present invention has been devised in view of the actual situation of the conventional oil pump, and the invention according to claim 1 provides a pump body having a drive shaft receiving hole and an inner peripheral surface of the drive shaft receiving hole. An oil pump comprising: a bearing portion provided; and a drive shaft that is pivotally supported by the bearing portion and is driven to rotate to change a fluid pressure in the pump body to perform a pump action, A tapered surface inclined in a diameter increasing manner from the front end side of the drive shaft that is bearing in the bearing portion toward the inner side of the pump body is formed on the inner peripheral surface of the bearing portion or the outer peripheral surface of the drive shaft. It is characterized by.

  According to this invention, during the pump operation, a high discharge pressure acts on the drive shaft from a predetermined portion in the radial direction inside the pump body, the drive shaft is bent and deformed, and one end side of the drive shaft is a bearing. If you try to contact a part of the inner peripheral surface of the part, this part will be absorbed by the taper surface, preventing the occurrence of a single contact between the two, preventing the occurrence of uneven load on the bearing part Is done. As a result, an increase in the surface pressure between the drive shaft and the bearing portion is suppressed, so that the drive shaft can be rotated smoothly at all times.

  The invention according to claim 2 is applied to a so-called variable displacement vane pump, and includes a pump body having a drive shaft accommodation hole, a bearing portion provided on an inner peripheral surface of the drive shaft accommodation hole, and the pump body. A drive shaft that is rotationally driven by the bearing portion at one end side, a rotor that is rotatably accommodated in the pump body and is rotationally driven by the drive shaft, and an outer peripheral portion of the rotor. A plurality of vanes provided in a plurality of slots so as to be movable in and out in a radial direction, and accommodated in the pump body so as to be swingable around a swing fulcrum, and a plurality of pump chambers together with the rotor and vanes on the inner periphery At least one of the first plate member and the second plate member, and a first plate member and a second plate member provided on both sides in the axial direction of the cam ring. A suction port that is provided on the outer side and opens to a region where the volumes of the plurality of pump chambers increase, a discharge port that opens to a region where the volume of the plurality of pump chambers decreases, and spaces on both sides on the outer peripheral side of the cam ring. The volumes of the plurality of pump chambers are changed by controlling the differential pressure between the first fluid pressure chamber and the second fluid pressure chamber formed separately, and the first fluid pressure chamber and the second fluid pressure chamber. And a pressure control means, and at least a tapered surface that gradually increases in diameter from one end edge side of the drive shaft toward the rotor is formed on the inner peripheral surface of the bearing portion on the suction port side. It is said.

  In this variable displacement type vane pump, when the eccentric amount of the cam ring with respect to the rotor is large, the pressure difference between the suction port and the discharge port becomes large. Even if bending deformation of the drive shaft occurs, the taper surface is formed on the inner peripheral surface of the bearing portion as described above, so that occurrence of contact with the drive shaft is prevented, and smooth rotation is always obtained. It is done.

  The invention according to claim 3 has the same basic configuration as that of the invention according to claim 2, but is different in that the tapered surface is replaced with a bearing portion and at least in the bearing portion of the drive shaft. A taper shape was formed on the outer peripheral surface of the end so as to reduce the diameter from the end of the drive shaft toward the rotor.

  According to this invention, by forming the outer peripheral surface of the end portion of the drive shaft into a tapered surface, the outer peripheral surface of the end portion of the drive shaft and the inner peripheral surface of the bearing portion follow in a state where the drive shaft is bent and deformed. In this way, contact with each other is prevented. As a result, the surface pressure of the both decreases, so that the drive shaft can always rotate smoothly.

  Embodiments in which an oil pump according to the present invention is applied to a variable displacement vane pump will be described in detail below with reference to the drawings.

  That is, this variable displacement vane pump is applied to a power steering device for a vehicle, and as shown in FIGS. 1 and 2, a pump body formed by abutting a front body 2 and a rear body 3 as one plate member. 1, an adapter ring 5 fitted to the inner surface of the accommodating space 4 formed inside the pump body 1, and can swing in the left-right direction in FIG. 3 within a substantially elliptical space of the adapter ring 5. A cam ring 7 and a rotor 9 that is rotatably arranged on the inner peripheral side of the cam ring 7 and that is connected to a drive shaft 8 inserted into the pump body 1 are provided.

  Each component of the pump body 2 is formed of an aluminum alloy, and the rear body 3 is provided with a drive shaft housing hole 3a for housing one end portion 8a of the drive shaft 8 on the inner surface on the cam ring 9 side. ing.

  As shown in FIG. 2, the adapter ring 5 is provided with a position holding pin 6 for holding the position of the cam ring 7 in an arc-shaped support groove formed at a lower portion of the inner peripheral surface. A support surface having a predetermined area as a swing fulcrum of the cam ring 7 is formed in the vicinity of the left side of the position holding pin 6 in the drawing, that is, on the first fluid pressure chamber 10 side to be described later. The position holding pin 6 functions not as a swing fulcrum of the cam ring 7 but as a rotation stop of the cam ring 7 with respect to the adapter ring 5 while holding the position of the cam ring 7.

  The cam ring 7 is formed in a substantially annular shape, is disposed in the accommodating space 4 in an eccentric state with respect to the rotor 9, and is a seal member located substantially opposite to the position holding pin 6. A first fluid pressure chamber 10 and a second fluid pressure chamber 11 are separated from the adapter ring 5 via 23. The cam ring 7 is swingable toward the first fluid chamber 10 or the second fluid pressure chamber 11 with a predetermined position on the support surface of the adapter ring 5 as a swing center.

  The cam ring 7 and the rotor 9 are disposed in a state of being clamped by a disk-shaped pressure plate 12, which is the other plate member disposed on the bottom side of the rear body 3 and the accommodating space 4 at both axial end surfaces.

  The rotor 9 rotates in the direction of the arrow (counterclockwise) in FIG. 2 when the drive shaft 8 is rotationally driven by an engine (not shown). A plurality of slots 13 along the radial direction are formed at the interval positions. In each slot 13, vanes 14 are held so as to be able to protrude and retract radially toward the inner peripheral surface of the cam ring 7. Also, a substantially circular back pressure chamber 15 is provided at the inner peripheral end of each slot 13.

  Further, a pump chamber 16 is formed by two adjacent vanes 14 in a space formed between the cam ring 7 and the rotor 9, and the cam ring 7 is centered on a swing fulcrum of the support surface. The volume of the pump chamber 16 is increased or decreased by swinging.

  As shown in FIG. 2, the second fluid pressure chamber 11 is provided with a spring 17 whose one end is supported by a bolt-shaped spring retainer 24, and the cam ring 7 is always connected to the first fluid by the spring 17. The pressure chamber 10 is biased in the direction in which the volume of the pump chamber 16 is maximized.

  An arc-shaped suction port 18 is formed on the inner surface of the rear body 3 on the rotor 9 side in the suction region where the volume of each pump chamber 16 gradually increases as the rotor 9 rotates. The suction port 18 supplies hydraulic oil sucked from the reservoir tank via the suction passage 19 to the pump chambers 16.

  Further, in the discharge region where the volume of each pump chamber 16 is gradually reduced with the rotation of the rotor 9, the inner surface of the pressure plate 12 is connected to the arc-shaped discharge port 20 and is not shown. The working fluid discharged from the pump chamber 16 is introduced into the discharge-side high-pressure chamber 21 formed at the bottom of the front body 2 through the discharge port 20 and the discharge hole. The working fluid introduced into the discharge-side high-pressure chamber 21 is sent from a discharge passage (not shown) formed in the pump body 1 to a hydraulic power cylinder of the power steering device via a pipe 22.

  Further, a control valve 30 is provided inside the front body 2 so as to face in a direction orthogonal to the drive shaft 8. As shown in FIG. 2, the control valve 30 includes a spool valve 32 slidably received in a valve hole 31 formed in the front body 2, and the spool valve 32 in the left direction in FIG. A valve spring 34 that is urged to come into contact with the plug 33 of the valve hole 31 is formed between the plug 33 and the tip of the spool valve 32. And a high-pressure chamber 35 to be introduced.

  The fluid pressure downstream of the metering orifice is supplied to the storage chamber 36 of the valve spring 34. When the pressure difference between the storage chamber 36 and the high pressure chamber 35 exceeds a predetermined value, the spool valve 32 is connected to the valve spring 34. It moves to the right in the figure against the spring pressure.

  The first fluid pressure chamber 10 is connected to a pump suction chamber 38 of the valve hole 31 via a connection passage 37 when the spool valve 32 is located on the left in FIG. The low pressure from the suction port 18 is introduced through a suction hole (not shown) formed in the front body 2. Further, when the spool valve 32 slides to the right side due to the differential pressure, the pump suction chamber 38 is gradually cut off, and a high-pressure working fluid is introduced into communication with the high-pressure chamber 35. As a result, the pressure in the pump suction chamber 38 and the pressure upstream of the metering orifice are selectively supplied.

  On the other hand, the second fluid pressure chamber 11 does not have a connection passage provided in a conventional oil pump and is not directly connected to the control valve 30. The second fluid pressure chamber 11 is always connected to the suction passage 19 through an introduction hole 25 formed in the pressure plate 12 to introduce a suction side pressure (low pressure).

  The relief valve 39 provided inside the spool valve 32 is opened when the pressure in the storage chamber 36 reaches a predetermined level or higher, that is, when the operating pressure of the power steering device reaches a predetermined level or higher. This working fluid is allowed to escape.

  A bush 26 that is a bearing portion that rotatably supports one end portion 8a of the drive shaft 8 is fixed inside the drive shaft accommodation hole 3a of the rear body 3 by press-fitting. As shown in FIGS. 3A and 3B, the bush 26 is formed of a copper material in a substantially cylindrical shape, and its axial length is set to be smaller than the axial length of the drive shaft accommodation hole 3a.

  Further, on the inner peripheral surface of the bush 26, a substantially conical tapered surface 26a is formed on the entire inner peripheral surface so as to increase in diameter from the distal end side of the one end portion 8a toward the cam ring 7. 3A and 3B, the taper surface 26a is set to have a large inclination angle in order to make it easy to understand in the drawings, but in practice it is set to a taper angle in units of microns.

Further, as shown in FIG. 1, the bottom side of the drive shaft accommodation hole 3a communicates with the suction passage 19 through the communication hole 27. Hereinafter, the operation of this embodiment will be described. For example, when the pump is rotating at a low speed, that is, when the drive shaft 8 or the rotor 9 rotates at a low speed and the pump discharge amount is large and the pressure on the discharge port 20 side is large, the discharge pressure on the discharge port 20 side is The pressure difference between the suction port 18 and the suction port 18 is increased, and the maximum load applied to the drive shaft 8 acts via the rotor 9 in the diagonally upper right direction in the drawing as shown by the arrow in FIG.

  For this reason, as shown in FIG. 3A, the substantially central position of the drive shaft 8 is bent and deformed into a curved shape protruding toward the suction port 18, and the one end portion 8a side is slightly deformed into an inclined shape.

  However, since the inner peripheral surface of the bush 26 is a tapered surface 26a, the outer peripheral surface of the one end portion 8a of the drive shaft 8 deformed into the inclined shape is absorbed by the tapered surface 26a. Prevents contact between the outer peripheral surface and the inner peripheral surface of the bush.

  As a result, the occurrence of local uneven load on the inner peripheral surface of the bush 26 is prevented, and an increase in surface pressure between the outer peripheral surface of the drive shaft 8 and the inner peripheral surface of the bush 26 is suppressed. As a result, the drive shaft 8 can always rotate smoothly.

  In addition, an arcuate gap C is formed between the lower surface side of the outer peripheral surface of the one end portion 8a of the drive shaft 8 and the lower end side of the tapered surface 26a opposite thereto. Therefore, the pump oil leaking between one side surface of the rotor 9 and the inner end surface of the rear body 3 facing the rotor 9 flows into the gap C, and the space between the drive shaft 8 and the bush 26 is sufficiently and positively provided. Lubricate. Therefore, the lubrication performance between the two is improved, and the smooth rotation of the drive shaft 8 is promoted.

  Further, the pump oil that has flowed into the gap C is sucked from the communication hole 27 toward the suction passage 19 and flows in the gap C, so that the lubricating performance between the two and 26 is further improved.

  Further, since the tapered surface 26a is formed on the entire inner peripheral surface of the bush 26, the suction port 18 side always has an enlarged diameter tapered surface at any position in the circumferential direction regardless of the mounting position of the bush 26. It becomes possible to form.

  Further, the cam ring 7 swings in the direction of the second fluid pressure chamber 11 due to the working fluid pressure in the first fluid pressure chamber 10 during normal pump rotation or the like, and the eccentric amount is small. When the differential pressure is reduced, a large load in the radial direction is not generated on the drive shaft 8. For this reason, as shown in FIG. 3B, the drive shaft 8 is prevented from being bent and deformed, so that no contact between the outer peripheral surface of the one end 8 a and the inner peripheral surface of the bush 26 occurs. Therefore, smooth rotation of the drive shaft 8 is obtained.

  In this embodiment, since the tapered surface 26a is formed in a substantially conical shape on the entire inner peripheral surface of the bush 26, the entire inner peripheral surface can be cut into a tapered shape while rotating the bush 26. Work is easy.

  As described above, the tapered surface 26a is formed on the entire inner peripheral surface of the bush 26. However, the tapered surface 26a can also be formed only on the side where the drive shaft 8 protrudes and is deformed.

  Further, since the bush 26 is made of a soft copper material compared to the iron material, it is possible to improve the wear resistance with the drive shaft 8.

  Further, the copper bush 26 has a so-called contact between its inner peripheral surface and the outer peripheral surface of the one end portion 8a of the drive shaft 8, that is, the outer peripheral surface of the drive shaft 8 is in sliding contact with the inner peripheral surface of the bush 26. However, it takes time for the contact area between the bush 26 and the drive shaft 8 to increase. However, by forming the tapered surface 26a on the inner peripheral surface of the bush 26, the bush 26 and the drive shaft 8 are formed from the beginning. It is possible to increase the contact area.

  FIG. 5 shows an embodiment corresponding to claim 3. In this embodiment, a tapered surface 8b is formed on the entire outer peripheral surface of one end portion 8a of the drive shaft 8 instead of forming a tapered surface on the bush 26. FIG. It is. The tapered surface 8b is formed in a reduced diameter from the tip end side of the one end portion 8a of the drive shaft 8 to the center side. The tapered surface 8b is also formed with a large inclination angle so that it can be easily seen in the drawing, but is actually set to an extremely small angle.

  Therefore, according to this embodiment, when the drive shaft 8 is bent and deformed as described above, the taper surface 8b of the one end portion 8a can prevent contact with the inner peripheral surface of the bush 26. The same effect as the embodiment can be obtained.

  The technical ideas other than the invention described in the claims, as grasped from the embodiment, will be described below.

  (1) The oil pump according to claim 1 or 2, wherein the tapered surface is formed in the entire outer peripheral surface area of the bearing portion.

  According to the present invention, since the tapered surface is formed on the entire inner peripheral surface of the bearing portion, it is possible to always form a tapered surface having an enlarged diameter on the suction port side regardless of the mounting position of the bearing portion. .

  Further, when the pressure is high, the amount of bending deformation of the drive shaft is large and the inclination becomes large. Therefore, the clearance between the drive shaft and the bearing portion on the discharge port side is increased by the tapered surface. As a result, the lubricating oil is easily introduced into the clearance, and the lubricity between the drive shaft and the bearing portion is improved.

  (2) The oil pump according to (1), wherein the bearing portion is formed by a cylindrical bush.

  In order to form the tapered surface on the inner peripheral surface of the bush, the inner peripheral surface can be formed by tapering while rotating the bush. Therefore, the processing operation is easy.

  (3) The drive shaft housing portion is formed in an inclined shape so as to gradually increase in diameter toward the suction port side from the end portion side of the drive shaft toward the rotor side. Oil pump as described in

  According to the present invention, since the drive shaft accommodating portion itself is formed in an inclined shape, a conventional bearing portion can be used.

  (4) The oil pump according to (2), wherein a communication passage is provided for communicating the drive shaft housing portion and the suction port.

  Since oil leaking from the rotor side is actively discharged into the communication path through the drive shaft housing portion, fluidity of the oil inside the bearing portion is ensured, and the bearing portion and the drive shaft Lubricity is improved.

  (5) The oil pump according to any one of (1) to (2), wherein the bearing portion is made of a copper material.

  Since the bearing portion (bush) is made of a soft copper material compared to the iron material, it is possible to improve the wear resistance with the drive shaft.

  Also, the bearing portion of the copper material is a so-called contact between the inner peripheral surface and the outer peripheral surface of the end of the drive shaft, that is, the outer peripheral surface of the drive shaft is in sliding contact with the inner peripheral surface of the bearing portion, and the inner peripheral surface is somewhat It takes time until the contact area between the bearing portion and the drive shaft increases due to wear, but by increasing the contact area between the bearing portion and the drive shaft from the beginning by forming a tapered surface on the inner peripheral surface of the bearing portion It becomes possible.

  The present invention is not limited to the configuration of the above embodiment. For example, the angle of the tapered surface 26a of the bush 26 can be arbitrarily set, and the molding material of the bush 26 can be freely changed. Is possible.

  Furthermore, this oil pump can be applied to various oil pumps such as a trochoid pump and a gear gear pump in addition to the variable displacement vane pump.

It is the sectional view on the AA line of FIG. 2 which shows embodiment of the oil pump which concerns on this invention. It is the BB sectional drawing of FIG. 1 which shows the same oil pump. A is a principal part sectional view showing the deformation of the drive shaft and the action of the bush provided in the present embodiment, and B is a principal part sectional view showing the action of the bush when the drive shaft is not deformed. It is the schematic which shows the state in which the discharge pressure from the discharge port in this embodiment acts on a drive shaft. It is principal part sectional drawing of the oil pump which shows embodiment corresponding to invention of Claim 3.

Explanation of symbols

1 ... Pump body 3 ... Rear body (first plate member)
3a ... Drive shaft accommodating hole 7 ... Cam ring 8 ... Drive shaft 8a ... One end 8b ... Tapered surface 9 ... Rotors 10 and 11 ... First and second fluid pressure chambers 12 ... Pressure plate (second plate member)
13 ... Slot 14 ... Vane 16 ... Pump chamber 18 ... Suction port 20 ... Discharge port 26 ... Bush 26a ... Taper surface

Claims (3)

A pump body having a drive shaft receiving hole;
A bearing portion provided on an inner peripheral surface of the drive shaft accommodation hole;
One end side is pivotally supported by the bearing portion, and a drive shaft that performs a pump action by changing the fluid pressure in the pump body by rotational driving;
An oil pump comprising:
A tapered surface inclined in a diameter increasing manner from one end side of the drive shaft bearing in the bearing portion toward the inner side of the pump body is formed on the inner peripheral surface of the bearing portion or the outer peripheral surface of the drive shaft. Oil pump characterized by A pump body having a drive shaft receiving hole;
A bearing portion provided on an inner peripheral surface of the drive shaft accommodation hole;
A drive shaft provided on the pump body, one end side of which is rotationally driven by the bearing portion;
A rotor housed rotatably in the pump body and driven to rotate by the drive shaft;
A plurality of vanes provided in a plurality of slots formed on the outer peripheral portion of the rotor so as to be able to protrude and retract in a radial direction;
A cam ring that is accommodated in the pump body so as to be swingable around a swing fulcrum, and forms a plurality of pump chambers together with the rotor and vanes on the inner peripheral side;
A first plate member and a second plate member provided on both axial sides of the cam ring;
A suction port that is provided on at least one side of the first plate member or the second plate member and opens to a region where the volumes of the plurality of pump chambers increase, and discharge that opens to a region where the volumes of the plurality of pump chambers decrease Port,
A first fluid pressure chamber and a second fluid pressure chamber formed by separating spaces on both sides of the outer periphery of the cam ring;
Pressure control means for changing the volume of the plurality of pump chambers by controlling a differential pressure between the first fluid pressure chamber and the second fluid pressure chamber,
An oil pump characterized in that at least an inner peripheral surface of the bearing portion on the suction port side has a tapered surface that gradually increases in diameter from one end edge side of the drive shaft toward the rotor. A pump body having a drive shaft receiving hole;
A bearing portion provided on an inner peripheral surface of the drive shaft accommodation hole;
A drive shaft provided on the pump body, one end side of which is rotationally driven by the bearing portion;
A rotor housed rotatably in the pump body and driven to rotate by the drive shaft;
A plurality of vanes provided in a plurality of slots formed on the outer peripheral portion of the rotor so as to be able to protrude and retract in a radial direction;
A cam ring that is accommodated in the pump body so as to be swingable around a swing fulcrum, and forms a plurality of pump chambers together with the rotor and vanes on the inner peripheral side;
A first plate member and a second plate member provided on both axial sides of the cam ring;
A suction port that is provided on at least one side of the first plate member or the second plate member and opens to a region where the volumes of the plurality of pump chambers increase, and discharge that opens to a region where the volumes of the plurality of pump chambers decrease Port,
A first fluid pressure chamber and a second fluid pressure chamber formed by separating spaces on both sides of the outer periphery of the cam ring;
Pressure control means for changing the volume of the plurality of pump chambers by controlling a differential pressure between the first fluid pressure chamber and the second fluid pressure chamber,
An oil pump characterized in that a taper shape is formed on an outer peripheral surface of an end portion existing in at least the bearing portion of the drive shaft so as to reduce the diameter from the end portion of the drive shaft to the rotor side.

Images