JP3844469B2 - Vane pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a vane pump mainly used as a vacuum pump.
[0002]
[Prior art and problems to be solved]
Engine oil is supplied as lubricating oil to a vane pump equipped as a negative pressure source of a vehicle. Oil supply is indispensable to prevent wear of the rotor shaft, rotor, vane, cam surface, etc. that make up the vane pump.However, if the oil supply amount is excessive, the oil compression state is caused by the oil accumulated in the pump operating chamber. And a large pressure is generated in the working chamber, thereby reducing the durability of the vane pump.
[0003]
As a countermeasure, Patent Document 1 proposes a device that discharges oil that has flowed back into the working chamber to the outside. However, in this device, when oil enters the working chamber, the above-described excessive pressure is applied. There is no effect to prevent the occurrence, and it is not always sufficient from the viewpoint of protecting the vane pump.
[0004]
[Patent Document 1]
JP-A-8-14174 [0005]
[Means for Solving the Problems]
The present invention includes a rotor supported by a pump shaft, a plurality of vanes supported by the rotor so as to freely advance and retreat in a radial direction, and a housing formed with an annular cam surface in which the tip of the vane slides. In the vane pump in which the working chamber defined between the vanes expands and contracts with the rotation of the rotor positioned eccentrically with respect to the cam surface, thereby generating a pump action. Grooves were formed in the circumferential direction so as to face each other, and the grooves were provided only in a predetermined area in front of the vane .
[0006]
[Action / Effect]
According to the present invention, since the degree of sealing between the vane and the rotor is reduced by the grooves formed in the circumferential direction on the rotor, the working chamber in the compression stroke and the working chamber in the discharge stroke ahead of the working chamber are provided. When the pressure difference between them increases, the pressure escapes from the high pressure side working chamber to the low pressure side working chamber through the groove and the gap between the rotor and the vane. Due to this action, when the working chamber in the compression stroke becomes a high compression state due to oil intrusion due to intrusion of oil, this oil is released to the working chamber on the low pressure side, so that excessive pressure is not generated in the working chamber. can do.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1 or FIG. 2, 1 is a vane pump housing, 2 is a pump shaft, 3 is a rotor, and 4 is a vane. An annular cam surface 5 formed of a parallel cylindrical surface is formed inside the housing 1, and the pump shaft 2 is rotatably supported at a position eccentric to the cam surface 5. A rotor 3 is fixed to the pump shaft 2. When the pump shaft 2 is driven by external power from an engine or the like, the rotor 3 rotates inside the housing 1.
[0008]
A cover plate 6 is attached to the housing 1 so as to close an opening that forms the cam surface 5, thereby sealing a space inside the cam surface in which the rotor 3 is accommodated.
[0009]
A plurality of (in this case, three) vane grooves 7 are formed in the rotor 3 in a radial manner, and the vanes 4 are accommodated in the respective vane grooves 7 so as to be slidable in the radial direction. The vane 4 is given an outward urging force by centrifugal force when rotating together with the rotor 3 and hydraulic pressure or air pressure introduced to the groove bottom of the vane groove 7. As a result, when the rotor 3 rotates, the vane 4 defines the working chambers 8 (8a to 8c) before and after the vane 4 while maintaining the state in which the tip end thereof is in contact with the cam surface 5.
[0010]
Reference numerals 9 and 10 respectively denote a suction port and a discharge port provided in the housing 1. The suction port 9 is formed so as to open facing the working chamber in a region where the volume of the working chamber 8 defined between the two vanes 4 is substantially maximum (in FIG. The working chamber at the maximum volume is shown). The discharge port 10 is formed so as to open facing the working chamber in the vicinity of the rotation region where the volume of the working chamber 8 is substantially minimum.
[0011]
When the vane 4 positioned in front of the rotation of the working chamber 8 in the compression stroke reaches immediately before the discharge port 10, the working chamber 8 is in the most compressed state, and the compressed air when the vane 4 passes through the discharge port 10. Is discharged to the outside from the discharge port 9, and the compression stroke is completed (8b in FIG. 1 indicates the working chamber in the most compressed state). Thereafter, the volume of the working chamber 8 gradually increases with the rotation of the rotor 3 and becomes a discharge-suction stroke (8c in FIG. 1 indicates a working chamber in the discharge stroke). When the volume of the working chamber 8 expands to some extent during the discharge stroke, the suction port 8 opens into the working chamber 7 to enter the suction stroke, and air is sucked from the outside. The pump is operated by repeating this suction and discharge.
[0012]
In the present invention, a groove is formed in the circumferential direction on the outer peripheral portion of the rotor 3 so as to face the sliding surface 4 a of the vane 4. In this embodiment, as shown in FIGS. 4 and 5, grooves 11a, 11b, and 11c are formed on the entire circumference at the three convenient locations at both the axial end and the central portion of the rotor 3, respectively. It is. Further, as shown in FIG. 3, a groove 12 having a predetermined length is formed in the circumferential direction on the cam surface 5 facing the vane 4 in front of the rotation that defines the most compressed working chamber 8b.
[0013]
In the configuration described above, lubricating oil enters the working chamber 8 when the pump is operated, and when the amount exceeds a certain level, the oil is compressed in the compression stroke, and high pressure is generated in the working chamber 8b of FIG. At this time, with the rise of the high pressure, a large differential pressure is generated between the working chamber 8b in the compression stroke and the working chamber 8c in the discharge stroke in front thereof. At this time, since the grooves 11a to 11b face the side surface of the vane 4, the air density between the vane 4 and the vane groove 7 is slightly low. Therefore, the high pressure in the working chamber 8b is increased between the vane 4 and the vane groove. 7 is released to the low pressure side working chamber 8c through the gap and the grooves 11a to 11c. In this way, it is avoided that the internal pressure of the working chamber 8b becomes excessive, so that the vane 4 and the cam surface 5 are prevented from being worn.
[0014]
Further, in this embodiment, since the groove 12 is formed so as to face the vane 4 in front of the rotation of the working chamber at the time of the most compression, the high pressure generated in the working chamber 8b by the oil compression is further reduced through the groove 12. There is also an effect that the high pressure of the working chamber 8b is suppressed by escaping to the working chamber 8c which is the side. However, if it is intended to relieve the high pressure during oil compression only with this groove 12, it is necessary to set the groove width and depth sufficiently large. Since the contact surface pressure between the vane 4 and the cam surface 5 at the provided portion becomes excessive and the durability is impaired, it is not preferable. In the present invention, the groove 11 is provided in the rotor 3 to increase the number of paths through which the high pressure in the working chamber is released to the low pressure side. Therefore, the groove 12 does not need to be large enough to impair the performance and durability of the pump.
[0015]
6 and 7 show another embodiment of the present invention. This is because the circumferential groove 11 formed in the rotor 3 is provided only in a predetermined area in the rotational direction indicated by an arrow with respect to the vane (vane groove 7) as shown. As described above, the effect of releasing the high pressure in the working chamber when the oil compression is generated can be expected only by forming the groove 11 in a limited region in front of the vane. Further, in the configuration in which the grooves 11a and 11c are formed at both ends of the rotor as in the first embodiment, when the side surface of the vane 4 is worried, the central portion in the axial direction of the rotor 3 as in this embodiment. By adopting a configuration in which the groove 11 is formed only in the groove, it is possible to avoid the problem of wear as described above.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a first embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of the first embodiment.
FIG. 3 is a perspective view of the vicinity of a groove according to the first embodiment.
FIG. 4 is an external perspective view of the rotor according to the first embodiment.
FIG. 5 is a longitudinal sectional view of the rotor according to the first embodiment.
FIG. 6 is an external perspective view of a rotor according to a second embodiment of the present invention.
FIG. 7 is a longitudinal sectional view of a rotor according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vane pump housing 2 Pump shaft 3 Rotor 4 Vane 5 Cam surface 6 Cover plate 7 Vane groove 8 (8a-8c) Working chamber 9 Suction port 10 Discharge port 11 (11a-11c) Groove 12 Groove

Claims (3)

A rotor supported by the pump shaft; a plurality of vanes supported by the rotor so as to freely advance and retreat in a radial direction; and a housing formed with an annular cam surface on which the tip of the vane slides. On the other hand, in the vane pump in which the working chamber defined between the vanes expands and contracts with the rotation of the rotor positioned eccentrically to generate a pump action.
In the rotor, a groove is formed in the circumferential direction so as to face the sliding surface of the vane with respect to the rotor ,
The said groove | channel is provided only in the predetermined area | region ahead of rotation with respect to the vane, The vane pump characterized by the above-mentioned.   The vane pump according to claim 1, wherein a plurality of the grooves are provided in the axial direction of the rotor. The vane pump according to claim 1, wherein a groove is formed in the circumferential direction on the cam surface so as to face a vane positioned in front of rotation of the working chamber in the most compressed state .

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