JP2007231802A - Vane pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vane pump capable of control with high responsiveness while maintaining high volumetric efficiency. <P>SOLUTION: The vane pump 1 is provided with a rotor 3 provided with a vane 2, a cam ring 4, a movable side plate 8 blocking both side parts of the cam ring 4 and the rotor 3 and forming a pump chamber between a suction port 5 and a delivery port 6, and a fixed side plate 9. A port block 10 is arranged on a back surface side of the movable side plate 8, and a back pressure chamber 11 is formed between the movable side plate 8 and the port block 10. A introduction channel 12 introducing delivery fluid from the delivery port 6 to the back pressure chamber 11 is connected to the back pressure chamber 11. The introduction channel 12 includes a branch point 13, a first throttle valve 15 which is a variable throttle valve and a second throttle valve 16 which is a fixed throttle valve are provided in an upstream side and in a downstream side respectively. Pressure in the back pressure chamber 11 is adjusted by controlling the first throttle valve 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable discharge amount type vane pump capable of adjusting a discharge amount.

  Conventionally, in a vane pump used for a fuel supply pump of a diesel engine, a liquid power transmission device, or the like, a disk-like rotor is rotatably disposed in a cam ring. Then, both side surfaces of the rotor and the cam ring are closed by side plates, so that a pump chamber is formed between the outer peripheral surface of the rotor and the inner peripheral surface of the cam ring, that is, the cam surface. A plurality of vane grooves extending in the radial direction are formed in the rotor, and the vanes are inserted into the vane grooves so as to be able to reciprocate.

  The vane is urged by a working fluid pressurized from the bottom of the vane groove or an elastic member provided at the inner end of the vane groove, and the tip of the vane is in contact with the cam surface. Then, the working fluid introduced from the suction port is discharged from the discharge port while being pressurized by the vane in the pump chamber.

  Conventionally, a vane pump capable of appropriately changing the discharge amount has also been proposed. For example, Patent Document 1 describes a vane pump in which the center of a cam ring and the rotation center of a rotor are deviated to change the discharge amount.

  Furthermore, as a proposal that the side plate (side plate) is pushed by the high pressure in the pump chamber to maintain an appropriate clearance and the load on the rotor can be reduced, a pressure chamber is formed on the back side of the side plate, and the pressure chamber is formed in the pressure chamber. Supplying a high pressure that counteracts the high pressure is performed (Patent Document 2).

JP-A-5-52188 Japanese Patent Laid-Open No. 6-207589

  By the way, the following problems are pointed out in a general vane pump. Particularly when the vane pump is used as a high-pressure fuel pump, the volume efficiency in the low rotation range is low. This volumetric efficiency will be described with reference to FIG. 6, which is a graph showing the relationship between the required discharge amount of a conventional general vane pump and the pump capacity. First, the required discharge amount indicated by a line segment abcd requires a large amount of fuel supply, that is, a pump discharge amount, since it is necessary to start the engine during ab when starting. After the engine is started, the required discharge amount increases as the rotational speed increases as indicated by the line cd. On the other hand, the capacity of the actual pump is poor in volumetric efficiency in the low rotation range, and draws a curve as shown by the line segment ef in the figure. That is, the volumetric efficiency is deteriorated as indicated by the region surrounded by the broken line gh and the line segment ef indicating the pumping capacity when there is no deterioration in the volumetric efficiency in the low rotation range. Under such circumstances, the pump capacity must be able to meet the demand for the discharge amount as described above. Therefore, it is necessary to secure a discharge amount at point e or higher at point e. For this reason, surplus pump work, that is, useless work of the pump increases as the rotation speed increases. In order to eliminate such a decrease in volumetric efficiency and improve volumetric efficiency, it is necessary to reduce the clearance between the vane and the inner wall of the pump chamber. On the other hand, the reduction in clearance is the cause of pump seizure. There is concern about becoming.

  For example, there is a vane pump as disclosed in Patent Document 1 as a proposal for reducing the surplus pump work and the wasteful work of the pump as described above, but even such a vane pump has the following disadvantages. There is concern. In the vane pump described in Patent Document 1, the volume of the pump chamber is variable by biasing the center of the cam ring and the rotation center of the rotor, more specifically, making the cam ring movable and making the distance from the rotor drive shaft variable. Therefore, it may be difficult to perform highly responsive control while satisfying the sealing performance, that is, maintaining high volumetric efficiency. Furthermore, the pump having such a configuration is limited to a non-equilibrium type, and when discharging at a high pressure is assumed, there is a problem that a load on the drive shaft is high and an increase in size of the pump is inevitable.

  Then, this invention makes it a subject to provide the vane pump which can perform control with high responsiveness, maintaining high volumetric efficiency.

  In addition, although it becomes the structure which loads a high voltage | pressure to the pressure chamber of the side plate back surface side of patent document 2, the objective is to stabilize the pressure balance of the side plate both sides.

  To achieve this object, a vane pump according to the present invention is provided with a rotor provided with a plurality of vanes provided so as to be reciprocally movable in the radial direction and biased radially outward, and rotatably accommodates the rotor. A cam ring in which tips of the plurality of vanes are slidably contacted with a cam surface formed on a peripheral surface; and a pair of side plates that close both sides of the cam ring and the rotor to form a pump chamber between the suction port and the discharge port; , At least one of the pair of side plates is a movable side plate, a back pressure chamber formed on the back side of the movable side plate, an introduction path for introducing discharge fluid from the discharge port into the back pressure chamber, and the introduction A pressure regulating means for fluid introduced into the back pressure chamber from a path is provided (Claim 1). By adopting such a configuration, the pressure in the back pressure chamber is adjusted, the movable side plate is positively moved to adjust the clearance (side clearance) between the movable side plate, the rotor, and the vane to induce an internal leak, The discharge amount can be adjusted. Thereby, high volumetric efficiency can be maintained. In the vane pump, improvement in volumetric efficiency is particularly required at the time of starting the pump, and when the pump is started, the pressure on the back pressure chamber side is increased to reduce the clearance. However, there is a period during which the clearance is reduced with respect to the pump life. Compared with a pump that is short and always operates with a narrow clearance, the risk of seizure can be reduced. Moreover, since the pressing force of the movable side plate is generated by changing the balance between the pressure in the pump chamber and the pressure in the back pressure chamber, the movable side plate is moved, so that high responsiveness can be ensured.

  The pressure adjusting means in such a vane pump includes a return path that branches from a branch point provided in the introduction path, a first throttle valve that is disposed upstream of the branch point, and a downstream side of the branch point. A second throttle valve, wherein at least one of the first throttle valve and the second throttle valve is a fixed throttle valve, and the other is a variable throttle valve whose throttle rate is changed by a throttle rate control means. It can be set as the structure provided (Claim 2). By adopting such a configuration, the pressure generated by changing the ratio of the throttle between the first throttle valve and the second throttle valve is applied to the back pressure chamber, which is caused by the differential pressure from the pressure in the pump chamber. The clearance for realizing the required discharge amount can be immediately created.

  The throttle rate control means in such a vane pump can be configured to change the throttle rate of the variable throttle valve in accordance with the required discharge amount and / or the required pressure of the fluid discharged from the discharge port. Item 3). Thereby, a desired fluid supply can be realized efficiently. Further, the throttle rate control means in such a vane pump changes the throttle rate of the variable throttle valve so that the pressure in the back pressure chamber decreases in response to a pump drive command to stop the discharge from the discharge port. It is desirable that the configuration be configured as follows (claim 4). In the present invention, since a high pressure is applied to the back pressure chamber and the movable side plate is pressed against the rotor side, the discharge of the fluid from the pump chamber is stopped, that is, the pressure in the pump chamber is reduced. At this time, if the movable side plate is strongly pressed against the vane and the rotor side, it may be a cause of seizure, which is a measure for avoiding this. Various methods such as an area stop and a time stop such as DUTY control can be adopted as the variable stop method. Further, the diaphragm ratio control means may be of any type such as an electromagnetic type or a mechanical type.

  In the vane pump having such a configuration, a seal between the movable side plate and the cam ring is required. In particular, since a high pressure in the pump chamber may be applied between the movable side plate and the cam ring, a sufficient sealing performance must be ensured even when such a high pressure acts. Therefore, it is desirable that such a vane pump has a configuration in which an O-ring and a backup ring disposed on the outer peripheral side of the O-ring are attached to the contact portion between the movable side plate and the cam ring. Further, when the O-ring and the backup ring are mounted in this way, the inner peripheral shape of the backup ring that comes into contact with the O-ring has a small diameter on the side close to the cam ring and a mortar having a large diameter on the side far from the cam ring. It is desirable that the O-ring is housed in a ring housing groove provided on a side wall of the movable side plate facing the cam ring (Claim 6). When the backup ring is arranged on the outer peripheral side of the O-ring, the O-ring receiving the high pressure in the pump chamber presses the backup ring arranged on the outer peripheral side. Then, since the mortar-shaped shape, that is, the backup ring having a tapered cross section receives a force that pushes out toward the cam ring by the O-ring, the sealing performance can be improved. For the same purpose, the inner peripheral shape of the backup ring in contact with the O-ring is a mortar shape having a small diameter on the side close to the movable side plate and a large diameter on the side far from the movable side plate, together with the O-ring. It can also be set as the structure accommodated in the ring accommodation groove provided in the side wall facing the said movable side plate of a cam ring (Claim 7). This is a configuration in which a ring receiving groove is provided on the cam ring side.

  However, the width of the backup ring in the direction coinciding with the depth direction of the ring receiving groove is equal to or less than the depth of the ring receiving groove in order to make the side clearance close to 0, that is, to make the distance between the movable side plate and the cam ring close to 0. It is desirable that the dimensions are as follows.

  According to the present invention, the movable side plate forming the pump chamber of the vane pump is provided with the pressure regulating means for supplying the pressure to the back pressure chamber formed on the back side of the movable immediate plate, thereby having high responsiveness. It is possible to adjust the side clearance by moving the movable side plate and control the internal leak amount to adjust the discharge amount. Further, the volumetric efficiency can be improved by reducing the side clearance when the pump is started.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  First, a schematic configuration of the vane pump 1 of the present invention will be described with reference to FIG. The vane pump 1 of this embodiment is used as a fuel supply pump mounted on a diesel engine, and is a high-pressure pump for supplying the liquid sucked from the fuel tank 30 by the feed pump 32, that is, fuel to the common rail 31. It is.

  A vane pump 1 includes a rotor 3 provided with a plurality of vanes 2 provided so as to be capable of reciprocating in the radial direction and biased outward in the radial direction, and a cam surface formed on the inner peripheral surface of the rotor 3 so as to be rotatable. 4a is provided with a cam ring 4 in which the tip of the vane 2 is in sliding contact. In addition, a pair of side plates 8 and 9 are provided which form a pump chamber 7 between the suction port 5 and the discharge port 6 by closing both sides of the cam ring 4 and the rotor 3. One of the pair of side plates 8 and 9 is a movable side plate 8 and the other is a fixed side plate 9. A port block 10 is disposed on the back side of the movable side plate 8, and a back pressure chamber 11 is formed between the port block 10 and the movable side plate 8. The back pressure chamber 11 is connected to an introduction path 12 for introducing the discharge fluid from the discharge port 6 into the back pressure chamber 11. The movable side plate 8 moves so that the side clearance S shown in FIG. 2 is adjusted between about 0 and 0.1 mm by the balance between the pressure in the back pressure chamber 11 and the pressure in the pump chamber 7.

  The introduction path 12 has a branch point 13. One of the paths branched from the branch point 13 introduces the discharge fluid into the pressure distribution chamber 11, and the other returns the discharge fluid to the fuel tank 30 as a return path 14. It is supposed to let you. A first throttle valve 15 is disposed upstream of the branch point 13, and a second throttle valve 16 is disposed downstream of the branch point 13. At least one of the first throttle valve 15 and the second throttle valve 16 is a fixed throttle valve with a fixed throttle ratio, and the other is a variable throttle valve that can change the throttle ratio, together with the return path 14. It constitutes the pressure adjusting means in the present invention. In the present embodiment, the first throttle valve 15 is a variable throttle valve, and the second throttle valve 16 is a fixed throttle valve.

  The first throttle valve 15 that is a variable throttle valve is constituted by an electromagnetic valve, and is connected to an ECU 19 corresponding to a throttle rate control means. The ECU 19 changes the throttle rate of the first throttle valve 15 so that the pressure in the back pressure chamber 11 decreases in response to a pump drive command to stop the discharge from the discharge port 6.

  Between the cam ring 4 and the movable side plate 8 arranged as described above, an O-ring 17 is attached in combination with a backup ring 18 at a portion indicated by a symbol A in FIG. The O-ring 17 and the backup ring 18 are accommodated in a ring accommodation groove 8a provided on a side wall facing the cam ring 4 of the movable side plate 8, as shown in FIG. . Regarding the positional relationship between the O-ring 17 and the backup ring 18, the O-ring 17 is disposed on the inner peripheral side, and the backup ring 18 is disposed on the outer peripheral side so as to contact the O-ring 17. The inner peripheral shape of the backup ring 18 has a mortar shape in which the side close to the cam ring 4 has a small diameter and the side far from the cam ring 4, that is, the side close to the port block 10 has a large diameter. That is, the cross-sectional shape of the backup ring 18 is tapered.

  Further, the width W of the backup ring 18 in the direction coinciding with the depth direction of the ring receiving groove 8a is a dimension equal to or smaller than the depth D of the ring receiving groove 8a. This is a measure for realizing the side clearance S = 0 by bringing the movable side plate 8 and the cam ring 4 into close contact with each other while ensuring sealing performance. Therefore, when the backup ring 18 is made of an elastic material, the width W of the backup ring 18 can be made slightly larger than the depth D of the ring receiving groove 8a.

  Regarding the control of the vane pump 1 configured as described above, Table 1 that summarizes the policy, FIG. 3 that is a graph showing the relationship between the required discharge amount and the pump capacity, and the control of the back pressure chamber pressure when the ignition is OFF This will be described with reference to FIG.

  First, when the ignition is ON, the first throttle valve 15 is opened. As a result, the pressure in the back pressure chamber 11 is made substantially the same as the discharge pressure (discharge pressure≈back pressure chamber pressure). This is a control for quickly raising the pressing force of the movable side plate 8 to the cam ring 4 side, reducing the side clearance, and improving the volumetric efficiency of the vane pump 1. A control parameter for performing such control is an ignition signal. In FIG. 3, a line segment abcd indicates the required discharge amount, and a large amount of fuel supply, that is, a pump discharge amount, is required because it is necessary to start the engine during ab at the start time. The capacity of the vane pump 1 is a capacity that can cover the discharge amount between the abs when the side clearance is reduced. In the vane pump 1 of the present embodiment, the discharge amount indicated by the line segment ij is secured.

  The ECU 19 opens the throttle area with respect to the first throttle valve 15 when the period between ab at the start of the engine passes and the engine is in an idling state where a discharge amount corresponding to the operating state (the number of revolutions) is required. Control to be changed between fully closed is started (j point). At this time, the pressure in the back pressure chamber 11 has a relationship of discharge pressure ≧ back pressure chamber pressure. As a control parameter during idling to normal operation, an injection amount instruction value into the cylinder and a rail pressure value in the common rail 31 are used. Using these values, the back pressure chamber pressure is set so that the required discharge amount indicated by line segment kl, line segment mn, line segment op, etc. in FIG. Adjusted. That is, the vane pump 1 adjusts the side clearance by adjusting the pressure difference in the back pressure chamber 11 and the pressure in the pump chamber 7 to achieve a desired required discharge amount and required discharge pressure. By performing such an operation, it is possible to significantly reduce the surplus pump capacity that has occurred in the conventional vane pump.

  Next, when the ignition is OFF, the ECU 19 fully closes the first throttle valve 15 and creates a state of discharge pressure >> back pressure chamber pressure at once. This is because the first throttle valve 15 is fully closed, the back pressure chamber pressure is quickly lowered, and the pressing force of the movable side plate 8 due to the back pressure chamber pressure is immediately increased as shown in FIG. This is intended to reduce the squeezing force. Even when the ignition is turned off, the engine continues to rotate due to inertia, and the discharge pressure is gradually reduced. On the other hand, the first throttle valve 15 is fully closed, the back pressure chamber pressure is immediately reduced, and an excessive pressing force of the movable side plate 8 can be avoided.

  The vane pump 1 is controlled under the policy described above. A high pressure acts between the cam ring 4 and the movable side plate 8 of the vane pump 1 as shown in FIG. 2 during operation. However, when the O-ring 17 is pressed in the radial direction, the backup ring 18 is cam ring. High sealing performance can be maintained because it protrudes to the 4th side.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, the first throttle valve 15 may be a fixed throttle valve, and the second throttle valve 16 may be a variable throttle valve. However, when the position of the throttle valve is changed in this way, the opening / closing control of the variable throttle valve is opposite to that in the above embodiment.

  Moreover, although the said Example is a fuel supply pump with which a diesel engine is mounted | worn, the vane pump of this invention is applicable also to the fuel pump used for other than a motor vehicle, and another hydraulic mechanism.

  Moreover, in the said Example, as shown in FIG. 2, it is set as the structure which accommodated the O ring 17 and the backup ring 18 in the ring accommodation groove | channel 8a provided in the side wall facing the cam ring 4 of the movable side plate 8. FIG. On the other hand, a configuration as shown in FIG. That is, the O ring 17 and the backup ring 18 can be accommodated in the ring accommodation groove 4 a provided on the side wall of the cam ring 4 facing the movable side plate 8. In the case of such a configuration, the inner peripheral shape of the backup ring 18 is a mortar shape in which the side close to the movable side plate 8 has a small diameter and the side far from the movable side plate 8, that is, the side close to the fixed side plate 9 has a large diameter. It has become. That is, the cross-sectional shape of the backup ring 18 has a tapered shape that is different from the state shown in FIG. Even with such a configuration, high sealing performance between the cam ring 4 and the movable side plate 8 can be ensured.

It is the figure which showed the schematic structure by making the principal part of a vane pump into a cross section. It is sectional drawing to which the A section in FIG. 1 was expanded. It is the figure which showed the relationship between the request | requirement discharge amount and pump capability in the vane pump of an Example. It is a figure which shows control of the back pressure chamber pressure at the time of ignition OFF. It is explanatory drawing which shows the state which accommodated the O ring and backup ring in the other Example in the ring accommodation groove | channel. It is the figure which showed the relationship between the request | requirement discharge amount and pump capacity in the conventional vane pump.

Explanation of symbols

Reference Signs List 1 vane pump 2 vane 3 rotor 4 cam ring 5 suction port 6 discharge port 7 pump chamber 8 movable side plate 8a ring receiving groove 9 fixed side plate 10 port block 11 back pressure chamber 12 introduction path 13 branch point 14 return path 15 first throttle valve 16 first Double throttle valve 17 O-ring 18 Backup ring 19 ECU
30 Fuel tank

Claims (8)

A rotor provided with a plurality of vanes provided so as to be capable of reciprocating in the radial direction and biased outward in the radial direction;
A cam ring that rotatably accommodates the rotor, and a tip of the plurality of vanes is in sliding contact with a cam surface formed on an inner peripheral surface thereof;
A pair of side plates that closes both sides of the cam ring and the rotor to form a pump chamber between the suction port and the discharge port;
Among the pair of side plates, at least one is a movable side plate, a back pressure chamber formed on the back side of the movable side plate,
An introduction path for introducing the discharge fluid from the discharge port into the back pressure chamber;
A vane pump comprising pressure regulating means for fluid introduced into the back pressure chamber from the introduction path. The vane pump according to claim 1, wherein
The pressure adjusting means includes a return path that branches from a branch point provided in the introduction path;
A first throttle valve disposed upstream of the branch point;
A second throttle valve disposed downstream of the branch point,
A vane pump characterized in that at least one of the first throttle valve and the second throttle valve is a fixed throttle valve, and the other is a variable throttle valve whose throttle rate is changed by a throttle rate control means. The vane pump according to claim 2,
The vane pump, wherein the throttle rate control means changes the throttle rate of the variable throttle valve in accordance with a required discharge amount and / or a required pressure of fluid discharged from the discharge port. The vane pump according to claim 2 or 3,
The throttle rate control means changes the throttle rate of the variable throttle valve so that the pressure in the back pressure chamber decreases in response to a pump drive command to stop discharge from the discharge port. . The vane pump according to any one of claims 1 to 4,
A vane pump characterized in that an O-ring and a backup ring disposed on the outer peripheral side of the O-ring are attached to a contact portion between the movable side plate and the cam ring. The vane pump according to claim 5, wherein
A side wall facing the cam ring of the movable side plate together with the O-ring as a mortar shape in which the inner peripheral shape of the backup ring in contact with the O-ring has a small diameter near the cam ring and a large diameter on the side far from the cam ring A vane pump characterized in that the vane pump is housed in a ring housing groove provided in the housing. The vane pump according to claim 5, wherein
The inner peripheral shape of the backup ring in contact with the O-ring is a mortar shape having a small diameter on the side close to the movable side plate and a large diameter on the side far from the movable side plate, and faces the movable side plate of the cam ring together with the O ring. A vane pump which is housed in a ring housing groove provided on a side wall. The vane pump according to claim 6 or 7,
The vane pump according to claim 1, wherein a width of the backup ring in a direction coinciding with a depth direction of the ring receiving groove has a dimension equal to or smaller than a depth of the ring receiving groove.

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