JP4759474B2 - Vane pump - Google Patents

Description

  The present invention relates to a vane pump in which a rotor and a vane slidable in the radial direction of the rotor are arranged inside a cam ring, and a precompression stroke is provided in a transition section in which a transition is made from a suction stroke to a discharge stroke.

  In many cases, the vibration and noise during operation of the vane pump are problematic, and the configuration of the vane pump aimed at reducing such vibration and noise has been studied. In particular, the pressure in the pump chamber suddenly changes from the suction pressure to the discharge pressure at the switching portion between the suction stroke in which the pump chamber volume increases and the discharge stroke in which the pump chamber volume decreases between adjacent vanes. It is known that sudden changes in pressure cause noise. Therefore, in the part where the suction stroke is switched to the discharge stroke, the pump chamber is not connected to the suction port and the discharge port, and the cam ring inner diameter is adjusted so that the pressure in the pump chamber gradually increases from the suction pressure to the discharge pressure. An increasing pre-compression stroke is provided to prevent sudden pressure fluctuations in the pump chamber.

  However, the degree of pressure increase in the pump chamber during the pre-compression stroke is determined by the cam ring inner diameter and the position of the suction port and discharge port, so the pressure increase during the pre-compression stroke is optimal for all load conditions from high pressure to low pressure. Is difficult to set. For example, if the degree of pressure increase in the pre-compression stroke is optimized to the low pressure side, pre-compression is insufficient under high pressure conditions, and the pressure in the pump chamber rises rapidly when the pump chamber communicates with the discharge port. Conversely, if the degree of pressure increase in the precompression stroke is optimized to the high pressure side, precompression becomes excessive under low pressure conditions, and the pressure in the pump chamber becomes too high compared to the discharge pressure.

  The vane pump is provided with a mechanism that pushes the vane against the cam ring by guiding the discharge pressure to the back pressure chamber provided at the bottom of the vane. However, when the pressure in the pump chamber exceeds the discharge pressure, the pressing force decreases. There is a problem that a phenomenon in which the vane is separated from the cam ring (hereinafter referred to as vane separation) occurs. As a technique for solving this problem, Japanese Patent Laid-Open No. 5-223062 discloses a technique for providing a passage for guiding the pressure of the pump chamber in the pre-compression stroke to the back pressure chamber of each vane constituting the pump chamber. Yes.

Japanese Patent Laid-Open No. 5-223062

  In the vane pump disclosed in Japanese Patent Laid-Open No. 5-223062, the excessive high pressure generated during the pre-compression stroke under low pressure conditions is guided to the vane back pressure chamber to prevent the vane from separating, but the pressure in the pump chamber is excessive. The rise itself has not been solved. An excessive increase in pressure in the pump chamber is applied to the shaft via the rotor. This pressure creates an unbalance of the force acting on the shaft, causing the shaft to vibrate and possibly causing noise. In addition, an excessive increase in the pressure in the pump chamber causes a large difference in the pressure acting on both sides of the vane. Thereby, the sliding resistance between the vane and the vane groove increases, and the responsiveness of the vane is impaired.

  An object of the present invention is to provide a low-noise vane pump that prevents vane separation and reduces shaft vibration due to excessive rise in pressure in the pump chamber regardless of the discharge pressure level.

  In order to achieve the above object, in the vane pump of the present invention, the pressure increase is limited so that the pressure in the pump chamber in the pre-compression stroke becomes equal to the discharge pressure. For this purpose, in the vane pump of the present invention, a communication passage is provided for connecting the pump chamber in the pre-compression stroke and the back pressure groove leading the discharge pressure via the check valve, and the back pressure groove is provided in the direction in which the check valve is closed. The discharge pressure inside is configured to act. With the above configuration, the pressure in the pump chamber in the pre-compression stroke steadily increases until reaching the discharge pressure, and sudden pressure fluctuations can be prevented when opening to the discharge port. In addition, even if the pressure rise in the precompression stroke becomes excessive under low pressure conditions, the check valve opens when the discharge pressure is exceeded, preventing an excessive pressure rise and increasing the pressure in the back pressure chamber of the vane in the precompression stroke. Can be guided to prevent the vanes from separating. Further, since the excessive pressure rise can be removed at any time by the action of the check valve, the precompression section may be arranged long with a margin, and the processing accuracy can be relaxed.

  Further, in the above configuration, the back pressure groove portion connected to the communication path, that is, the back pressure groove portion connected to the back pressure chamber of the vane in the pre-compression stroke is changed to the back pressure chamber of the vane out of the pre-compression stroke. It is good to divide from the back pressure groove part to be connected, and to connect both back pressure groove parts via a restriction. As a result, the vane back pressure increases when the check valve opens due to the increase in the pump chamber pressure and oil flows into the vane back pressure chamber in the precompression stroke. In this way, the back pressure groove in the section is separated from the back pressure groove in the other sections.

  If the check valve is not responsive, the check valve is eliminated and the pump chamber in the pre-compression stroke and the back pressure groove in the section are connected by a communication path. You may provide the notch which becomes thin gradually in the reverse direction to a pump rotation direction. As a result, when the pump chamber pressure in the pre-compression section is too high than the discharge pressure, the hydraulic oil is released to a large volume chamber called a back pressure groove through the communication path, and the pump chamber pressure is higher than the discharge pressure. To prevent becoming too much. Further, since a high pressure is guided to the back pressure groove, the vanes are prevented from being separated. Further, by providing the notch, it is possible to adjust and optimize the communication timing and the way of releasing the hydraulic oil.

  According to the present invention, when the pump chamber pressure becomes higher than the discharge pressure in the precompression stroke, the hydraulic oil is released, and conversely, a high pressure is introduced into the vane back pressure chamber. Rise and vane separation can be prevented. As a result, noise due to shaft vibration and vane separation can be reduced.

(Example)
Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a variable displacement vane pump as an embodiment of the vane pump of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. 2 is a cross-sectional view taken along the line BB in FIG.

  In FIG. 2, 1 is a front body constituting the main body, and 2 is a rear cover. A shaft 4 is supported on the front body 1 via a bearing 3, and the shaft 4 inputs a rotational driving force of an engine or the like (not shown) to the rotor 5. In FIG. 1, an adapter 6 is fitted in the front body 1, and a cam ring 7 is arranged with its center eccentric from the rotor 5. The cam ring 7 can roll inside the adapter 6 with the support pin 8 as the center. When the rotation speed increases, the cam ring 7 swings to the right to reduce the amount of eccentricity, thereby reducing the discharge amount per rotation and reducing the overall pump. It has a mechanism to keep the discharge flow rate constant. The rotor 5 is provided with a plurality of slit-like vane grooves 9, and a plurality of vanes 10 are held so as to be slidable in the radial direction. A region surrounded by two adjacent vanes 10, the rotor 5, and the cam ring 7 constitutes a pump chamber 16, and the pumping action of suction and discharge is performed by increasing or decreasing the volume. A vane back pressure chamber 11 for pressing the vane 10 against the cam ring 7 is provided at the end of the plurality of vane grooves 9 close to the shaft 4. A discharge pressure is introduced into the chamber 11. The back pressure groove 13 a is the same as that indicated by the dotted line in FIG. 1, and is connected to the individual vane back pressure chambers 11 in an annular shape. As shown in FIG. 2, the back pressure groove 13a communicates with the discharge oil reservoir 22 in which the discharged oil is stored, so that the discharge pressure is applied to the individual vane back pressure chambers 11.

  Next, details of the pump action will be described. FIG. 3 shows only the pressure plate 12 taken out. 1 is overwritten by broken lines so that the overall positional relationship between the suction port 14 and the discharge port 15 in FIG. 3 can be understood. In FIG. 1, when the rotor rotates counterclockwise, the volume of the pump chamber 16 increases in the suction stroke, so that oil is sucked from the suction port 14. On the other hand, since the volume of the pump chamber 16 decreases in the discharge stroke, oil is discharged from the discharge port 15. The hydraulic oil discharged from the discharge port 15 is discharged out of the pump via the discharge oil reservoir 22.

A pre-compression stroke X indicated by an arrow in FIG. 1 is a transition section from the suction stroke to the discharge stroke, and the pump chamber 16 is not opened in either the suction port 14 or the discharge port 15. In the pre-compression stroke X, the pressure is increased by adjusting the volume of the pump chamber 16 to gradually decrease, and the internal pressure of the pump chamber 16 plays a role of smoothly increasing from the suction pressure to the discharge pressure. In the prior art, if the pre-compression stroke X is too long, the internal pressure of the pump chamber 16 becomes too higher than the discharge pressure under a low discharge pressure, and if the pre-compression stroke X is too short, the discharge pressure is high. There was a problem that pre-compression was insufficient and sudden pressure fluctuation occurred when the discharge port 15 was opened. In this embodiment, the pressure release port 18 is provided in the pressure plate 12 in the section of the pre-compression stroke X, and the check valve 19 as shown in FIG. Downstream of the check valve 19, the pressure in the back pressure groove 13 b is guided through the communication path 20. The position of the communication path 20 is overwritten with a dotted line in FIG. 3 so that the positional relationship between the pressure relief port 18, the communication path 20, and the back pressure groove 13b can be easily understood. As shown in FIG. 3, the back pressure groove 13b is connected to the back pressure groove 13a via the throttle 21, and the discharge pressure is guided from the discharge oil reservoir 22 to the back pressure groove 13a. Therefore, the check valve 19 is normally pressed by the discharge pressure.

The operation of the check valve 19 is as follows. In the pre-compression stroke X, when the internal pressure of the pump chamber 16 is lower than the discharge pressure, the check valve 19 is not opened, so that pre-compression is performed. However, when the internal pressure of the pump chamber 16 becomes higher than the discharge pressure, the check valve 19 is opened, and the internal pressure of the pump chamber 16 does not increase any more. For this reason, the input of the unbalance force to the shaft 4 resulting from excessive increase in the internal pressure of the pump chamber 16 can be reduced. Furthermore, since the pump chamber 16 and the back pressure groove 13b communicate with each other through the communication passage 20 while the check valve 19 is open, high pressure due to pre-compression is introduced into the back pressure groove 13b. Since the back pressure grooves 13b and 13a are separated by the restriction 21, the high pressure guided to the back pressure groove 13b in the pre-compression stroke is higher than the discharge pressure that is the pressure of the other back pressure grooves 13a. A force that presses the vane against the cam ring prevents the vane from separating in the pre-compression stroke X.

The characteristics of the vane pump configured as described above will be described in comparison with the prior art. FIG. 4 shows the pressure plate 12 in the vane pump when there is no pressure relief port 18, check valve 19, communication path 20, etc., and FIG. 5 is a characteristic diagram of the pump chamber pressure and the vane back pressure at that time. First, the pump chamber pressure in the suction stroke is the suction pressure, that is, the atmospheric pressure. Next, before the pump chamber 16 opens to the discharge port 15, a pre-compression stroke is provided for increasing the pump chamber pressure from the suction pressure to the discharge pressure. The length of the precompression stroke is set between the optimum value at high pressure and the optimum value at low pressure so that the discharge pressure can be applied at both high and low pressures. Therefore, pre-compression becomes excessive as shown in FIG. 5 under a low pressure condition, and the pump chamber pressure may exceed the discharge pressure. Such an excessive increase in pump chamber pressure is not preferable because it may cause shaft vibration. Further, since the vane back pressure is always equal to the discharge pressure, there is a possibility that vane separation occurs due to insufficient vane pressing force in the pre-compression stroke.

  Next, the characteristics of the vane pump (FIG. 3) according to the present invention are shown in FIG. In this case, the characteristics in the intake stroke are not different from those in FIG. However, in the pre-compression stroke, when the pump chamber pressure becomes equal to or higher than the discharge pressure, the check valve 19 in FIG. 2 opens and the pump chamber pressure does not increase any more. On the other hand, when the check valve 19 is opened, the boosted pump chamber pressure is guided to the back pressure groove 13b through the communication path 20. Since the back pressure groove 13b is separated from the other back pressure grooves 13a by the throttle 21, the vane back pressure in the pre-compression stroke becomes higher than the discharge pressure as shown in FIG. 6, and the separation of the vanes is suppressed. By adjusting the diameter of the throttle 21, it is possible to optimize the degree of increase in the pump chamber pressure and the degree of increase in the vane back pressure in the precompression stroke.

  In FIG. 3, the back pressure groove 13a other than the pre-compression stroke X is shared, and the discharge pressure acts on the back pressure chamber 11 of each vane. However, in this configuration, the sliding friction generated at the tip of the vane 10 in the suction stroke. The power will increase. This is because, in the suction stroke, the pressure acting on the tip of the vane 10 is the pump chamber pressure, that is, the suction pressure, whereas the discharge pressure, which is the pressure of the back pressure groove 13a, acts on the lower end of the vane 10. Therefore, as shown in FIG. 7, the back pressure groove 13d in the suction stroke and the back pressure groove 13c in the discharge stroke are separated, the vane back pressure in the suction stroke is lowered, and the tip of the vane 10 is pressed against the cam ring 7. High-efficiency vane pumps that reduce sliding friction due to the above have been considered. Of course, application of the present invention to such a high-efficiency vane pump is also possible.

  Furthermore, in a conventional vane pump that does not have a pressure relief mechanism in the precompression stroke, the pump chamber pressure in the precompression stroke is too high compared to the discharge pressure as shown in FIG. A pressure plate 12 provided with a notch 23 as shown in FIG. 8 is often used in order to reduce sudden pressure fluctuations when it is sufficiently low and lower than the discharge pressure. However, such an arrangement of the notches 23 requires a fine angle accuracy, and there is a problem that manufacturing costs are increased. If the vane pump according to the present invention is designed with a margin in the length of the precompression stroke, the pump chamber pressure immediately before the discharge port opening is equal to the discharge pressure, so that notch machining is not required, thereby reducing costs. Can do.

  If there is a problem with the responsiveness of the check valve, the check valve may be eliminated and the pre-compression stroke pump chamber and the back pressure groove may be connected only by the communication path. FIG. 9 shows a pressure plate 12 having this configuration. In this case, the connection portion 18a between the pump chamber and the communication path is provided at a position where the pump chamber communicates with the suction port without opening. This is because if the pump chamber is open to the suction port and communicates with the back pressure groove, the back pressure groove under the discharge pressure flows into the suction port. Further, as shown in FIG. 9, a notch 24 is provided in the connecting portion 18a between the pump chamber and the communication passage so that the timing at which the pump chamber communicates with the back pressure groove can be finely adjusted and optimized.

The front view which carried out one section which shows one example of the vane pump of the present invention. Sectional drawing seen from the bottom face which shows one Example of the vane pump of this invention. The pressure plate front view in one Example of the vane pump of this invention. FIG. 4 is a front view of a pressure plate for comparison with the configuration of FIG. 3. FIG. 5 is a characteristic diagram of pump chamber pressure, vane back pressure, and separation amount in the vane pump of FIG. 4. The characteristic figure of the pump chamber pressure, the vane back pressure, and the separation amount in the vane pump of the present invention. The pressure plate front view in an example of a highly efficient vane pump. The pressure plate front view with a notch. The pressure plate front view which provided the notch in the connection part of a pump chamber and a communicating path as one Example of this invention.

Explanation of symbols

5 ... rotor, 7 ... cam ring, 10 ... vane, 11 ... vane back pressure chamber, 12 ... pressure plate, 13a, 13b ... back pressure groove, 14 ... suction port, 15 ... discharge port, 16 ... pump chamber, 18 ... pressure Extraction port, 19 ... check valve, 20 ... communication path, 21 ... throttle, 22 ... discharge oil reservoir, 23, 24 ... notch, X ... pre-compression stroke.

Claims (3)

The rotor and cam ring that are rotationally driven by the shaft are arranged eccentrically so that the vanes can enter and exit in the radial direction while sliding from the plurality of vane grooves provided on the rotor, and are provided at the end of each vane groove close to the rotor center The vane back pressure chamber is connected to a back pressure groove that guides the discharge pressure, and further includes a transition section between a suction stroke in which the volume of the pump chamber divided by adjacent vanes increases and a discharge stroke in which the volume decreases. In a vane pump connected by a pre-compression stroke in which the volume of the pump chamber is reduced without opening the suction port or the discharge port,
A communication passage that connects the pump chamber in the pre-compression stroke and the back pressure groove via a check valve is provided, and the discharge pressure in the back pressure groove acts in the closing direction of the check valve. Features vane pump.   2. The vane pump according to claim 1, wherein a connection portion between the communication passage and the back pressure groove is provided in a section of the back pressure groove where a vane back pressure chamber in a pre-compression stroke is connected, and the back portion in the section is further connected. A vane pump characterized in that the pressure groove and the back pressure groove in the other section are separated and connected through a throttle. The rotor and cam ring that are rotationally driven by the shaft are arranged eccentrically so that the vanes can enter and exit in the radial direction while sliding from the plurality of vane grooves provided on the rotor, and are provided at the end of each vane groove close to the rotor center The vane back pressure chamber is connected to a back pressure groove that guides the discharge pressure, and further includes a transition section between a suction stroke in which the volume of the pump chamber divided by adjacent vanes increases and a discharge stroke in which the volume decreases. In a vane pump connected by a pre-compression stroke in which the volume of the pump chamber is reduced without opening the suction port or the discharge port,
The pump chamber in the pre-compression stroke and the back pressure groove are connected by a communication passage, and a connection portion between the pump chamber and the communication passage is provided with a notch groove that gradually narrows in the direction opposite to the pump rotation direction. A vane pump characterized in that a back pressure groove section connected to a vane back pressure chamber in a pre-compression stroke and a back pressure groove in other sections are separated and connected through a throttle.

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