JP2004092395A - Vane pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vane pump capable of suppressing the vibration and noise resulting from the variation in an air content. <P>SOLUTION: A notch 52 for communicating a vane chamber 5 with a discharge port 4 in a pressure transition process from a suction process into a discharge process for the vane chamber 5 is formed in a side plate 50. In the vane pump 1, there is formed a cam major arc 21 for lessening the deviation in the radial direction by making each vane 2 be contact with a cam 20 in the pressure transition process from the suction process into the discharge process for the vane chamber 5. The cam major arc 21 is formed in the range 1.2 to 1.6 times the pitch P between each vane 2. Immediately after the vane chamber 5 ends the suction process, the notch 52 is communicated with the vane chamber 5, and formed so that the pressure in the vane chamber 5 is increased same as that of the discharge port 4 until the pressure transition process ends. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a vane pump which is used, for example, as a hydraulic pressure source for a vehicle and has a high content of air bubbles in a working fluid and is not stable.
[0002]
[Prior art]
Conventionally, as this kind of vane pump, as disclosed in Japanese Patent Application Laid-Open No. 2001-248569, for example, in order to adjust a pressure waveform in a pressure transition process from a suction process to a discharge process, precompression by a change in volume of a vane chamber is performed. And a notch that connects the vane chamber to the discharge port to mitigate the pressure change at the discharge port.
[0003]
[Problems to be solved by the invention]
By the way, the speed at which the pressure in the vane chamber rises depends on the compressibility of the hydraulic oil, and changes in particular depending on the bubble content of the hydraulic oil.
[0004]
However, in such a conventional vane pump, the pre-compression of the vane chamber is set so as to be optimal for a specific bubble content. There has been a problem that the pressure rise becomes excessive or insufficient during the transition process, and an impact pressure is generated, which causes vibration and noise of the vane pump.
[0005]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a vane pump capable of suppressing vibration and noise caused by a change in bubble content.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, a plurality of vanes slidably protruding from a rotating rotor, a cam that slidably contacts an outer peripheral end of each vane to define a vane chamber, and slidably contacts a side end of each vane. A side plate that defines a vane chamber, and a suction port that allows a working fluid to flow into the vane chamber during a suction stroke in which the vane chamber expands with rotation of the rotor on the side plate, and a vane chamber that rotates with rotation of the rotor. A discharge port through which the working fluid flows out from the vane chamber during the discharge stroke, and a notch connecting the vane chamber to the discharge port during the pressure transition process from the suction stroke to the discharge stroke. The present invention is applied to a vane pump in which each vane is brought into sliding contact with each other in a pressure transition stroke from a suction stroke to a discharge stroke to form a cam large arc portion in which radial displacement is reduced.
[0007]
The cam large arc portion is formed in the range of 1.2 to 1.6 times the pitch P of each vane, and the notch communicates the vane chamber with the discharge port at the beginning of the pressure transition process until the pressure transition process ends. Further, the pressure in the vane chamber is increased to the same level as the discharge port.
[0008]
The second invention is characterized in that, in the first invention, a cam large arc portion having substantially the same cam diameter is formed from the end of the suction port to the end of the discharge port.
[0009]
According to a third aspect, in the first or second aspect, the notch is formed at a position where the notch communicates with the vane chamber when the vane chamber blocks communication with the suction port.
[0010]
Function and Effect of the Invention
According to the first aspect, by forming the cam large arc portion in a range of 1.2 to 1.6 times the pitch P between the vanes, the pre-compression of the vane chamber is hardly performed in the pressure transition stroke. Air bubbles are compressed by the pressure of the discharge port guided through the notch from the beginning of the transition process, and the pressure of the vane chamber is increased to the same level as the discharge port. As a result, even when the bubble content is increased, the pressure is sufficiently increased in the pressure transition process. As a result, generation of impact pressure in the vane chamber can be avoided, and vibration and noise of the vane pump can be suppressed.
[0011]
According to the second aspect of the present invention, by forming the cam large arc portion from the end of the suction port to the end of the discharge port, the amount of pre-compression in which the vane chamber is compressed in the pressure transition stroke is minimized, and air bubbles are generated. Even when the content is increased, the pressure is sufficiently increased in the pressure transition process, and the vibration and noise of the vane pump can be effectively suppressed.
[0012]
According to the third aspect, the notch overlaps the vane chamber and communicates with the vane chamber almost simultaneously when the vane chamber blocks communication with the suction port, thereby maximizing the stroke in which the pressure of the discharge port is guided to the vane chamber via the notch. Pressure is sufficiently increased in the pressure transition process even when the bubble content is increased, and the vibration and noise of the vane pump can be effectively suppressed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a vane pump provided as a hydraulic pressure source mounted on a vehicle will be described with reference to the accompanying drawings.
[0014]
First, FIG. 1 shows an example of a vane pump to which the present invention can be applied. The vane pump 1 includes a rotor 30 rotatably supported by a casing (not shown), a slit 31 radially formed in the rotor 30, ten vanes 2 slidably projecting from the slit 31, and each vane. A cam 20 that slides the outer peripheral end of the vane 2 to define the vane chamber 5, and a side plate 50 that slides the side end of the rotor 30 and each vane 2 to define the vane chamber 5. Be composed.
[0015]
The rotation from the starting source is transmitted to the rotor 30 via a drive shaft (not shown), and the rotor 30 rotates as shown by an arrow in FIG. Each vane 2 slides its outer peripheral end against the inner peripheral surface of the cam 20 while moving in and out of the rotating rotor 30 in the radial direction to expand and contract the vane chamber 5.
[0016]
A pair of suction ports 3 and a pair of discharge ports 4 are formed in the side plate 50. Hydraulic oil is sucked from the suction port 3 into the vane chamber 5 that expands between the vanes 2 with the rotation of the rotor 30, and hydraulic oil is discharged from the vane chamber 5 that contracts between the vanes 2 to the discharge port 4. In the present embodiment, the suction port 3 communicates with the tank via a suction passage (not shown), and the discharge port 4 communicates with a hydraulic actuator (not shown) via a pump discharge passage.
[0017]
The side plate 50 is formed with a notch 52 extending from one end of the discharge port 4 in the circumferential direction. The notch 52 is recessed in a triangular groove shape, and its depth gradually decreases toward the tip 52a. The notch 52 communicates the vane chamber 5 with the discharge port 4 in a pressure transition step from a suction step to a discharge step.
[0018]
A back pressure groove 51 extending in the circumferential direction is formed in the side plate 50. The pressure of the discharge port 4 is guided to the back pressure groove 51, and each vane 2 is pushed out from the rotor 30 in the radial direction by this pressure.
[0019]
The cam 20 has a cam curve portion 23 for sliding each vane 2 in a radial direction by sliding each vane 2 in an area where the suction port 3 and the discharge port 4 are opened, and a pressure located between the suction port 3 and the discharge port 4. A cam large arc portion 21 in which the displacement in the radial direction is reduced by sliding the vanes 2 in a transition process. The cam large arc portion 21 is formed in a circular arc shape curved at a predetermined radius around the rotation axis of the rotor 30, and slides the vanes 2 while maintaining a state of protruding from the rotor 30 by a predetermined maximum amount. It has become.
[0020]
According to the present invention, the cam large arc portion 21 is formed in a range of 1.2 to 1.6 times the pitch P between the vanes 2 and the notch 52 is provided immediately after the vane chamber 5 completes the suction stroke. Is connected to the discharge port 4, and before the vane chamber 5 overlaps with and communicates with the discharge port 4, the pressure of the vane chamber 5 is increased to the same level as the discharge port 4. Hereinafter, a specific example of the embodiment shown in FIG. 2 will be described.
[0021]
FIG. 2 is an expanded view of the cam 20, the rotor 30, and the like, and the vane chamber 5 moves rightward as shown by a white arrow in the figure. If the pitch between adjacent vanes 2 is a pitch P, the cam large arc portion 21 is formed in a range of 1.2 to 1.6 times the pitch P.
[0022]
In this embodiment, the cam large arc portion 21 having substantially the same cam diameter is formed from the end 3 a of the suction port 3 to the end 4 a of the discharge port 4. That is, the cam large arc portion 21 is formed in substantially the entire area between the suction port 3 and the discharge port 4, and minimizes the amount of pre-compression in which the vane chamber 5 is compressed in the pressure transition stroke.
[0023]
Then, before the vane 2 enters the discharge stroke in which the vane chamber 5 contracts due to sliding contact with the cam curved portion 23, the vane chamber 5 overlaps the discharge port 4 and communicates.
[0024]
The notch 52 is formed at a position where the notch 52 overlaps and communicates with the vane chamber 5 almost at the same time when the communication with the suction port 3 is interrupted. In the present embodiment, assuming that the plate thickness of the vane 2 is t, the interval from the end 3a of the suction port 3 to the tip 52a of the notch 52 is about Pt. As a result, the notch 52 guides the pressure of the discharge port 4 to the vane chamber 5 immediately after the end of the suction stroke in the pressure transition process, and the pressure of the vane chamber 5 is reduced before the vane chamber 5 overlaps and communicates with the discharge port 4. 4 and ascending.
[0025]
The operation as described above will now be described.
[0026]
As the rotor 30 rotates, the vane chamber 5 defined between the vanes 2 expands in a region facing the suction port 3, sucks hydraulic oil from the suction port 3, and contracts in a region facing the discharge port 4. Then, the hydraulic oil is discharged to the discharge port 4.
[0027]
When the vane chamber 5 overlaps and communicates with the discharge port 4, if the pressure in the vane chamber 5 is significantly lower than that of the discharge port 4, the pressurized hydraulic oil in the discharge port 4 rapidly flows into the vane chamber 5, causing an impact. Pressure is generated in the vane chamber 5 and causes vibration and pressure pulsation of the vane pump 1.
[0028]
The speed at which the pressure in the vane chamber 5 rises depends on the compressibility of the hydraulic oil, and in particular, changes depending on the bubble content of the hydraulic oil. In the conventional device in which the vane chamber is pre-compressed by the cam curve portion so as to be optimal for a specific bubble content, the cam large arc portion is formed to be about 1.1 times the pitch P of each vane ( References: “Basic Mechanical Engineering Course 18 Hydraulic Engineering,” published by Asakura Shoten). Therefore, as shown in FIG. 5, for example, in a state where the bubble content is increased, the pressure rise is insufficient in the pressure transition step, and this causes a shock pressure to be generated as the vane chamber communicates with the discharge port.
[0029]
According to the present invention, by forming the cam large arc portion 21 in a range of 1.2 to 1.6 times the pitch P, the pre-compression of the vane chamber 5 by the cam curve portion 23 in the pressure transition stroke is hardly performed. The bubbles are sufficiently compressed by the pressure of the discharge port 4 guided through the notch 52 from the beginning of the transition process, and the pressure of the vane chamber 5 is increased to the same level as the discharge port 4. Thus, as shown in FIGS. 3 and 4, for example, even in a state where the bubble content is increased, the pressure is sufficiently increased in the pressure transition process. As a result, it is possible to avoid the generation of an impact pressure as the vane chamber 5 communicates with the discharge port 4, thereby suppressing the vibration and pressure pulsation of the vane pump 1. In FIG. 3, when the angle of the horizontal axis is α °, the vane chamber 5 communicates with the discharge port 4. However, as shown by the broken line in FIG. It can be seen that the pressure increase is sufficiently performed. As a result, vibration and noise of the vane pump 1 due to the fluctuation of the bubble content can be effectively suppressed.
[0030]
By forming the cam large arc portion 21 from the end 3a of the suction port 3 to the end 4a of the discharge port 4, the amount of precompression in which the vane chamber 5 is compressed in the pressure transition stroke is minimized, and the bubbles are contained. Even in the state where the rate is increased, the pressure is sufficiently increased in the pressure transition step, and the vibration and noise of the vane pump 1 can be effectively suppressed.
[0031]
The vane chamber 5 cuts off the communication with the suction port 3 and at the same time the notch 52 overlaps with the discharge port 4 to communicate with the discharge port 4, thereby maximizing the stroke in which the pressure of the discharge port 4 is guided to the vane chamber 5 through the notch 52. The vibration and noise of the vane pump 1 caused by the fluctuation of the bubble content can be effectively suppressed, and even when the bubble content is increased, the pressure is sufficiently increased in the pressure transition process, and the vibration and noise of the vane pump 1 are increased. Can be effectively suppressed.
[0032]
The present invention is not limited to the above-described embodiment, but can be applied to, for example, other than a hydraulic power source for a vehicle, and it is apparent that various changes can be made within the technical idea.
[Brief description of the drawings]
FIG. 1 is a side view of a vane pump to which the present invention is applied.
FIG. 2 is a developed view of the vane pump showing the embodiment of the present invention.
FIG. 3 is an operation characteristic diagram of the vane pump.
FIG. 4 is an operation characteristic diagram comparing the present invention and a conventional example.
FIG. 5 is an operation characteristic diagram of a vane pump showing a conventional example.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 vane pump 2 vane 3 suction port 4 discharge port 5 vane chamber 20 cam 21 cam large arc 23 cam curve 30 rotor 52 notch

Claims (3)

A plurality of vanes slidably projecting from the rotating rotor;
A cam that slides the outer peripheral end of each vane to define a vane chamber;
A side plate that defines a vane chamber by sliding a side end of each vane,
A suction port through which a working fluid flows into the vane chamber in a suction stroke in which the vane chamber expands with the rotation of the rotor on the side plate;
A discharge port for allowing the working fluid to flow out of the vane chamber in a discharge stroke in which the vane chamber contracts with the rotation of the rotor;
The vane chamber forms a notch communicating the vane chamber with the discharge port in a pressure transition stroke from the suction stroke to the discharge stroke,
In a vane pump in which a vane chamber is brought into contact with a cam in a pressure transition stroke from a suction stroke to a discharge stroke to form a large arc portion of a cam in which radial displacement is reduced by sliding each vane in contact with each other.
The cam large arc portion is formed in a range of 1.2 to 1.6 times the pitch P between the vanes,
The vane pump is characterized in that the notch communicates the vane chamber with the discharge port at the beginning of the pressure transition step, and the pressure in the vane chamber rises to the same level as the discharge port before the pressure transition step ends. 2. The vane pump according to claim 1, wherein the cam large arc portion having substantially the same cam diameter is formed from an end of the suction port to an end of the discharge port. 3. The vane pump according to claim 1, wherein the notch is formed at a position where the notch communicates with the vane chamber when the vane chamber blocks communication with the suction port.

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