JP2005264770A - Vane pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vane pump having the excellent projection property of vane in the inner peripheral surface direction of a cam ring in an area between the final end of an intake area and the start end of a discharge area. <P>SOLUTION: This vane pump is formed so that a first and second intake side back pressure grooves 25 and first and second discharge side back pressure grooves 28 can be formed in the opposed inner surfaces of a rear body 3 and a pressure plate. A first intake side opening 18 leading a pump intake pressure therein is formed in the inner surface of the rear body, and a second intake side opening leading a pressure lower than the pump intake pressure is formed in the inner surface of the pressure plate. The length of the final point 18b of the first intake side opening relative to the final point 23b of the second intake side opening is made shorter at an angle of approximately 10° in the circumferential direction, and the tip parts of the vanes are pulled out beforehand by acting a low pressure near a negative pressure on the second intake side opening side (23b side) on the tip parts of the vanes immediately after the final point 18b to improve the projection property of the vanes in the discharge area B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  As a vane pump used for vehicles, what was indicated in the following patent documents 1 is known.

  This vane pump is applied to a variable displacement type, and is provided integrally with a cam ring swingably accommodated in a pump body and a drive shaft inserted into the pump body, and rotates within the cam ring. The rotor, a plurality of slots formed along the radial direction on the outer periphery of the rotor, a plurality of vanes provided so as to be able to project and retract in the radial direction from within each slot, and the cam ring and the rotor from the axial direction. A pressure plate and a rear body for clamping are provided.

  In addition, an arc-shaped groove communicating with a back pressure chamber formed on the bottom side of the slot is formed on the inner surface of the rear body on the rotor side, and the arc-shaped groove is formed on the suction area groove and the discharge area side. The pressure on the suction side of the pump is introduced into the groove in the suction area.

Therefore, since the pressure on the pump suction side is applied to the base end portion side (back pressure chamber) of the vane in the suction region, the force for pressing the vane against the cam ring can be surely pressed against the cam ring. At the same time, since the vane is not pressed against the cam ring by an excessive force, the friction loss between the vane and the cam ring can be reduced.
JP 2003-172272 A

  However, in this conventional vane pump, as described above, the pressure on the pump suction side is introduced into the groove of the suction region, so that the vane jumps out during the transition from the suction region to the discharge region. There is a problem that the nature is bad.

  In particular, in the low-rotation state of the pump, since the centrifugal force acting on the vane is small, the deterioration of the vane pop-out property becomes remarkable.

  The present invention has been devised in order to solve the above-described conventional technical problem, and in order to ensure the pressing force of the vane against the inner peripheral surface of the cam ring during the operation of the pump, the vane tip at the end of the suction region It is intended to increase the vane pressing force by slightly reducing the pressure applied to the portion and increasing the pressure difference from the base end side of the vane.

  According to the first aspect of the present invention, in particular, a substantially annular vane back pressure groove communicating with the back pressure chamber is formed on the inner surface of one of the side plates facing the rotor. The pressure groove is divided into a suction side back pressure groove corresponding to the pump suction region and a discharge side back pressure groove corresponding to the pump discharge region, and the pump suction pressure is introduced into the suction side back pressure groove while the discharge A pump discharge pressure is introduced into the side back pressure groove, and a first suction side opening that communicates directly with the reservoir tank and opens to the suction region of the pump chamber is formed on the inner surface of the one side plate facing the rotor. Formed on the inner surface of the other side plate facing the rotor, communicating with the pump suction side through the pump chamber and opening to the suction region of the pump chamber facing the first suction side opening Second suction side opening The end point position of the first suction side opening when the pump chamber moves from the suction region to the discharge region in the rotation direction of the rotor is formed in a direction opposite to the rotor rotation direction than the end point position of the second suction side opening. It is characterized by a short setting.

  Generally, if the pressure at the suction side opening that opens in each pump chamber separated by each vane is extremely low, the pressure at the vane tip side will decrease, so the pressure from the vane base end side must be changed. In this case, the vane is pressed against the inner surface (cam surface) of the cam ring. However, as described above, if the pressure on the pump suction side is extremely low, bubbles are likely to be generated in the hydraulic fluid (oil), causing noise generation. May cause cavitation.

  Therefore, for example, in the middle region of the suction region where the volume increase rate of the pump chamber is large and the inflow amount of hydraulic fluid is large, a pressure slightly higher than the pump suction pressure is introduced into the first suction side back pressure groove, A low pump suction pressure may be introduced into each pump chamber on the tip side of the vane from the second suction side opening.

  Therefore, the vane located in the suction area applies the vane to the inner peripheral surface of the cam ring with a small pressure due to the differential pressure between the low pump suction pressure in each pump chamber and the pressure in the first suction side back pressure groove higher than this. It is possible to make contact (sliding contact).

  As a result, it is possible to reduce the frictional resistance between the vane and the cam ring, thereby reducing the engine power loss.

  In addition, when the vane passes through the first suction side opening when moving from the suction region to the discharge region, the pump chamber is disconnected from the first suction side opening, and the first and second suction sides The communication with the back pressure groove and the first and second discharge side back pressure grooves is also blocked, but only the communication with the vicinity of the end point of the second suction side opening is maintained. The second suction side opening does not communicate with the reservoir tank, and only the low pressure on the pump suction side is applied. That is, the hydraulic oil sucked into the pump chamber between the two vanes is subjected to a low pressure close to the negative pressure flowing in from the other pump chamber before the first suction side opening.

  As a result, the pressure around the front end of the vane on the rear side is lower than when the pressure is facing the first suction side opening, and the front end is pulled out from the slot side toward the cam ring by the low pressure in the pump chamber. Thus, the cam ring comes into contact with the inner peripheral surface of the cam ring before entering the discharge region.

  Immediately after that, at the time of transition to the discharge region, the base end side of the vane is pushed out by the normal high pump discharge pressure of each discharge side back pressure chamber supplied from each back pressure groove, and the tip end portion is pressed strongly against the cam ring. To do.

  Therefore, since the vane is drawn in the cam ring direction in advance from the suction region to the discharge region, the vane is moved in the direction of the inner peripheral surface of the cam ring during the transition from the suction region to the discharge region. Abrupt protrusion movement is prevented and the occurrence of impact sound is suppressed, and the pop-out property in the discharge region, that is, the responsiveness is improved.

  In addition, as described above, the tip of the vane abuts against the inner peripheral surface of the cam ring even after passing through the suction region, so that high sealing performance is ensured, so that the hydraulic fluid in the pump chamber is in another pump chamber in the suction region. It can also prevent leaks.

  Hereinafter, embodiments of a vane pump according to the present invention will be described in detail with reference to the drawings. In this embodiment, the present invention is applied to a variable displacement vane pump.

  That is, as shown in FIGS. 1 to 4, the vane pump includes a pump body 1 formed by abutting a front body 2 and a rear body 3 that is one side plate, and an accommodation space formed inside the pump body 1. 4, an adapter ring 5 fitted on the inner surface of the adapter ring 5, a cam ring 7 that can swing around a swing fulcrum pin 6 in a substantially elliptical space of the adapter ring 5, and an inner peripheral side of the cam ring 7 A rotor 9 that is freely arranged and is connected to a drive shaft 8 that is inserted into the pump body 1 is provided.

  The cam ring 7 is formed in a substantially annular shape, and is disposed in the receiving space 4 in an eccentric state with respect to the rotor 12, and the swing fulcrum pin 6 and a seal at a position substantially opposite thereto. The first fluid pressure chamber 10 and the second fluid pressure chamber 11 are separated via a member 51.

  The cam ring 7 and the rotor 9 are disposed so as to be sandwiched by a disk-shaped pressure plate 12, which is the other side plate disposed on the bottom side of the rear body 3 and the accommodating space 4 at both end surfaces in the axial direction.

  The rotor 9 rotates in the arrow direction (counterclockwise direction) in FIG. 1 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, 11 vanes 14 are held so as to be able to protrude and retract radially in the direction of the inner peripheral surface of the cam ring 7. Further, a substantially circular back pressure chamber 15 is provided continuously and integrally at the inner peripheral side end of each slot 13.

  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 swung around the swing fulcrum pin 6 as a fulcrum. By moving it, the volume of the pump chamber 16 is increased or decreased.

  As shown in FIG. 1, a compression coil spring 17 is disposed in the second fluid pressure chamber 11, and the cam ring 7 is always connected to the first fluid pressure chamber 10 side, that is, the volume of the pump chamber 16 is maximized. It is energizing in the direction to become.

  Further, the inner surface of the rear body 3 on the rotor 12 side in the suction region A (see FIGS. 3 and 4) in which the volume of each pump chamber 16 gradually increases with the rotation of the rotor 12 has an arcuate shape. One suction side opening 18 is formed.

  The first suction side opening 18 supplies hydraulic oil sucked from the reservoir tank to the pump chambers 16 via a suction port 19 and a suction passage (not shown).

  Further, the inner surface of the pressure plate 12 in the discharge region B (see FIGS. 3 and 4) in which the volume of each pump chamber 16 gradually decreases as the rotor 12 rotates, Two discharge-side openings 20 and discharge holes 21 communicating with the two discharge-side openings 20 are formed, and the pressure fluid discharged from the pump chamber 16 passes through the second discharge-side openings 20 and the discharge holes 21 to the bottom of the front body 2. It is introduced into the formed discharge side pressure chamber 22. The pressure fluid introduced into the discharge side pressure chamber 22 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.

  Further, as shown in FIG. 4, a second suction side opening 23 having a substantially arc shape is formed at an inner surface position of the pressure plate 12 facing the first suction side opening 18 of the rear body 3. This arc length is set to the same length as the suction area A.

  Further, a substantially identical first discharge side opening 24 is formed at an inner surface position of the rear body 3 facing the second discharge side opening 20 of the pressure plate 12, and the first discharge side opening 24 and the pressure are provided. The arc length of the second discharge side opening 20 on the plate 12 side is set to be substantially the same as that of the discharge region B. By forming the first and second discharge side openings 20 and 24 and the first and second suction side openings 18 and 23, the pressure balance on both sides of each pump chamber 16 is maintained.

  An arc-shaped first suction-side back pressure groove 25 is formed on the inner surface of the rear body 3 on the rotor 9 side at a position substantially facing the back pressure chamber 15 in the suction region A. The first suction side back pressure groove 25 is connected to the fluid passage between the valve outlet of the power steering device and the reservoir tank via the communication passage 50 and the return passage of the rear body 3.

  On the other hand, an arc-shaped second suction side back pressure groove 26 is formed at an inner surface position of the pressure plate 12 facing the first suction side back pressure groove 25 of the rear body 3, and this second suction side back pressure groove 26 is formed. The pressure groove 26 communicates with a relief passage 27 that communicates with a control valve 40 described later. The first suction-side back pressure grooves 25 and 26 are set such that their arc lengths are within the suction area A.

  In addition, an arc-shaped first discharge-side back pressure groove 28 communicating with the back pressure chamber 15 is formed at a position in the discharge region B of the rear body 3. The first discharge side back pressure groove 28 has a central portion located in the discharge region B, and both ends of the start point 28a side and the end point 28b side are both ends of the first suction side back pressure groove 25 in the suction region A. It is extended to the vicinity of the club. That is, when the pump chamber 16 formed between the two adjacent vanes 14 (14a and 14b in FIG. 3) shifts from the suction area A to the discharge area B, that is, the rear vane 14b is the first suction. When the vane 14a on the front side moves out of the side opening 18 and moves into the first discharge side opening 24, the back pressure chamber 15 in the slot 13 of the vane 14b on the rear side becomes the first suction side back pressure in the suction region A. It is formed so as not to communicate with the first discharge-side back pressure groove 28 temporarily out of the groove 25.

  On the other hand, on the inner surface of the pressure plate 12 on the rotor 9 side, as shown in FIG. 4, an arc shape extends from the area before the start end b1 of the discharge area B to the end a2 of the suction area A. The second discharge side back pressure groove 29 is formed. That is, the second discharge-side back pressure groove 29 has a start point 29a at the end point of the second suction-side opening 23 in the suction region A in the same manner as the end point 28b of the first discharge-side back pressure groove 28 in the discharge region B of the rear body 3. 23b, the end point 29b is located upstream of the end b2 of the discharge region B on the upstream side of the start end b1, and the portion S beyond that is the second suction side back pressure in the suction region A. The groove 26 is formed flat up to the position of the starting point 26a. Further, the second discharge-side back pressure groove 29 communicates with the discharge-side pressure chamber 22 through a throttle hole 30 formed in the pressure plate 12 so that the discharge pressure is introduced.

  The first suction side opening 18 formed on the rear body 3 side has a circumferential length shorter than the circumferential length of the second suction side opening 23 of the opposing pressure plate 12. Is set.

  That is, as shown in FIG. 4, the length of the second suction side opening 23 is set to be substantially the same as the length of the suction region A, and the start point 23a is the start point of the suction region A, as described above. While the position is almost the same as the position a1, the end point 23b is substantially the same position as the end point position a2 of the suction area A. On the other hand, as shown in FIG. 3, the first suction side opening 18 has its start point 18a located at the same position as the start point 23a of the second suction side opening 23, but the end point 18b is the second suction side opening. 23 is set at a position retracted from the end point 23b of the second end 23b, and is set at substantially the same position as the end point 25b of the first suction side back pressure groove 25. That is, the circumferential angle θ from the end point 23b of the second suction side opening 23 to the end point 18b of the first suction side opening 18 is set to be shorter by about 10 °.

  Therefore, when the pump chamber 16 formed between the two adjacent vanes 14 (14a and 14b in FIG. 3) shifts from the suction side to the discharge side, that is, the rear vane 14b is the first suction side. A pump chamber formed between the vane 14a on the front side when the back pressure chamber 15b of the slot 13 is disengaged from the end point 18b of the opening 18 and the end pressure 25b of the first suction side back pressure groove 25 is disengaged. 16 is set so as not to reach the end point 23 b of the second suction side opening 23 and to be in communication with the second suction side opening 23.

  The control valve 40 has the same configuration as that of the Japanese Patent Application Laid-Open No. 2003-172272. Briefly described, the control valve 40 is formed in the front body 2 as shown in FIG. A spool valve 42 slidably accommodated in the valve hole 41, and the spool valve 42 is urged to the left (in the direction of the first hydraulic pressure chamber 10) in FIG. A spring 44 to be brought into contact with, and a high pressure chamber 45 formed between the plug 43 and the tip of the spool valve 42 and into which a working hydraulic pressure upstream of a metering orifice (not shown) is introduced. The working hydraulic pressure downstream of the ring orifice is supplied to the storage chamber 46 of the spring 43. When the pressure difference between the storage chamber 46 and the high pressure chamber 45 exceeds a predetermined value, the spool valve 42 And moves in the right direction in the drawing against the pressure.

  The first hydraulic pressure chamber 10 is connected to the pump suction chamber 48 of the valve hole 41 through the connection passage 47a when the spool valve 42 is located on the left side, and the spool valve 42 slides to the right side by the differential pressure. In this case, the pump suction chamber 48 is gradually cut off so as to communicate with the high pressure chamber 45. As a result, the pressure in the pump suction chamber 48 and the pressure upstream of the metering orifice are selectively supplied.

  On the other hand, the second hydraulic pressure chamber 11 is connected to the storage chamber 46 via the connection passage 47b when the spool valve 42 is not operated, and the storage chamber 46 is gradually shut off as the spool valve 42 is operated. Connected to the suction chamber 48, the pressure downstream of the metering orifice and the pressure on the pump suction side are selectively supplied.

  The relief valve 49 provided inside the spool valve 42 is opened to release the hydraulic pressure when the pressure in the storage chamber 46 reaches a predetermined level or more. The hydraulic oil is supplied to the first suction side back pressure groove 25 of the rear body 3 through the relief passage 27.

  While the vane 14 is moving in the suction area A, the pressure on the pump suction side acts on the tip, and the hydraulic oil used in the power steering device is connected to the communication path 50 and the first suction side shown in FIG. The oil is introduced into the back pressure chamber 15 of the slot 13 via the back pressure groove 25, and this oil pressure acts on the base end portion of the vane 14. Therefore, since the hydraulic pressure in the back pressure chamber 15 is slightly higher than the pressure on the pump suction side, each vane 14 can be pushed out and reliably pressed against the inner peripheral surface of the cam ring 7.

  Further, this pressure is only slightly higher than the pressure on the pump suction side, and is much lower than the pump discharge pressure, so that the friction loss between the inner peripheral surface of the cam ring 7 and the vane 14 is reduced, and the pump is driven. Power can be reduced.

  Further, when the relief valve 49 is operated, the pump discharge oil flows directly from the relief valve 49 to the pump suction chamber, and the flow rate supplied to the power steering device is reduced. Since the pressure decreases due to the resistance, the vane 14 cannot be pushed out by this pressure.

  However, in this embodiment, as described above, the hydraulic oil relieved from the relief valve 49 is supplied to the second suction side back pressure groove 26 in the suction region A through the relief passage 27, so that the relief is performed. The vane 14 can be pushed out by the pressure of the hydraulic oil and can be brought into contact with the inner peripheral surface of the cam ring 7 with certainty.

  Therefore, in this embodiment, in any case, it is possible to reliably press the vane 14 against the cam ring 7 while sufficiently reducing the frictional resistance between the cam ring 7 and the vane 14 in the suction region A. .

  Further, in this embodiment, when the pump chamber 16 between the two adjacent vanes 14 moves from the suction area A to the discharge area B, that is, as shown in FIG. While passing through the side opening 18, the front vane 14a moves to the discharge side opening 28, and immediately before the pump chamber 16 between these vanes 14a, 14b moves to the discharge region B, the front vane Since the high pressure in the discharge-side back pressure grooves 28 and 29 in the discharge region B has already been supplied to the back pressure chamber 15 of the slot 13 of 14a, the vane 14a sufficiently pops out and reliably presses against the inner peripheral surface of the cam ring 7. It is done. In particular, since the discharge-side back pressure groove 29 on the pressure plate 12 side is formed with the throttle hole 30, the internal pressure is quickly increased and the high pressure is maintained, so that the vane 14 can be popped out.

  Further, as described above, when the vane 14 moves from the suction region A to the discharge region B and passes through the first suction side opening 18, the pump chamber 16 is disconnected from the first suction side opening 18. In addition, the communication with the first and second suction side back pressure grooves 25 and 26 and the first and second discharge side back pressure grooves 28 and 29 is also blocked, but the vicinity of the end point 23b of the second suction side opening 23 Only the communication with is maintained. This second suction side opening 23 does not communicate with the reservoir tank, and only the low pressure on the pump suction side acts, that is, the hydraulic oil sucked into the pump chamber 16 between the two vanes 14a and 14b. A low pressure close to the negative pressure flowing in from the other pump chamber 16 in front of the first suction side opening 18 is applied.

  As a result, the pressure around the front end of the vane 14b on the rear side is lower than that when the pressure around the first suction side opening 18 is faced. It is pulled out in the seven directions and is in contact with the inner peripheral surface of the cam ring 7 in advance before entering the discharge region B.

  Immediately after that, at the time of shifting to the discharge region B, the base end side of the vane 14 is pushed out by the normal high pump discharge pressure of each discharge side back pressure chamber 15 supplied from each back pressure groove 24, 29, and the tip. The portion is pressed strongly against the cam ring 7.

  Accordingly, since the vane 14 is drawn in the cam ring 7 direction after passing through the suction region A and before reaching the discharge region B, the vane 14 is moved in the cam ring 7 at the time of transition from the suction region A to the discharge region B. The abrupt protruding movement of the vane 14 in the circumferential direction is prevented, and the occurrence of collision hitting sound is suppressed, and the pop-out property in the discharge region B, that is, the responsiveness is improved.

  Further, as described above, the tip end portion of the vane 14 abuts against the inner peripheral surface of the cam ring 7 even after passing through the suction region A to ensure high sealing performance, so that the hydraulic fluid in the pump chamber 16 is sucked into the suction region 7. Leakage to other pump chambers 16 can also be prevented.

Further, since the circumferential angle of the position of the end point 23b of the second suction side opening 23 with respect to the position of the end point 18b of the first suction side opening 18 is set to an angle of about 10 °, the experimental results show that Generation | occurrence | production can reduce and the pop-out property of a vane can be improved.
The technical ideas other than the invention described in the claims, as grasped from the embodiment, will be described below.

  (1) A variable capacity type in which the volume of the pump chamber is variably controlled by swinging the cam ring, and one suction port and one discharge port are provided in the circumferential direction. The vane pump according to claim 1.

  In a normal fixed capacity type vane pump, a suction side opening and a discharge side opening are formed in a pair in the circumferential direction, so that each vane appears and disappears from each slot twice per rotation of the rotor. . For this reason, since the slot back pressure chamber provided in the suction area does not introduce suction pressure (reservoir tank pressure), the vanes cannot be sufficiently projected.

  However, in the variable displacement vane pump, since the suction and discharge strokes are performed once per rotation of the rotor, the slot back pressure chamber in the rotor provided in the suction region is inserted through the suction side back pressure groove. Even if the suction pressure is introduced, the vane can be sufficiently projected.

  The number of the plurality of vanes is set to 11, and the angle in the circumferential direction of the end point position of the second suction side opening with respect to the end point position of the first suction side opening is in a range of about 5 to 20 degrees. The vane pump according to claim 1, wherein the vane pump is set inside.

  According to the inventor's experiment, it has been found that by setting the length of the second suction side opening as described above, the occurrence of cavitation is reduced and the vane pop-out property is improved. More preferably, the angle is about 10 degrees.

It is the sectional view on the AA line of FIG. 2 which shows the vane pump of embodiment of this invention. It is the BB sectional drawing of FIG. 1 which shows the same vane pump. It is CC sectional view taken on the line of FIG. It is a front view of the pressure plate provided to this embodiment.

Explanation of symbols

1 ... Pump body 3 ... Rear body (side plate)
4 ... Accommodating space 7 ... Cam ring 8 ... Drive shaft 9 ... Rotors 10 and 11 ... First and second fluid pressure chambers 12 ... Pressure plate (side plate)
13 ... Slot 14 ... Vane 15 ... Back pressure chamber 16 ... Pump chamber 18 ... First suction side opening 18b ... End point 20 ... Second discharge side opening 23 ... Second suction side opening 23b ... End point 24 ... First discharge side opening 25 ... first suction side back pressure groove 26 ... second suction side back pressure groove 28 ... first discharge side back pressure groove 29 ... second discharge side back pressure groove A ... suction area B ... discharge area

Claims (1)

A rotor driven to rotate by a drive shaft;
A plurality of vanes provided in a plurality of slots formed on the outer periphery of the rotor so as to be able to appear and disappear in a radial direction;
Side plates disposed on both axial sides of the rotor;
A cam ring that is disposed on the outer peripheral side of the rotor and forms a plurality of pump chambers between the vanes and the side plates adjacent to the outer peripheral surface of the rotor while the tip of the vane is in sliding contact with the inner peripheral surface When,
A vane pump that is formed on the bottom side of the slot and includes a back pressure chamber that applies pressure in a protruding direction to the base end surface of the vane.
A substantially annular vane back pressure groove communicating with the back pressure chamber is formed on an inner surface of the one side plate facing the rotor,
The vane back pressure groove is divided into a suction side back pressure groove corresponding to the pump suction region and a discharge side back pressure groove corresponding to the pump discharge region, and a pump suction pressure or a pump suction pressure is formed in the suction side back pressure groove. While introducing a slightly higher pressure, a pump discharge pressure is introduced into the discharge-side back pressure groove,
Forming a first suction side opening that communicates directly with the reservoir tank and opens to the suction region of the pump chamber on the inner surface of the one side plate facing the rotor;
A second side plate that communicates with the pump suction side through the pump chamber and that opens to the suction area of the pump chamber on the inner side surface facing the rotor of the other side plate and facing the first suction side opening. Forming an inhalation side opening,
The end point position of the first suction side opening when the pump chamber moves from the suction region to the discharge region in the rotation direction of the rotor is set shorter than the end point position of the second suction side opening in the direction opposite to the rotor rotation direction. Vane pump characterized by that.

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