JPH0882292A - Vane pump - Google Patents

Abstract

PURPOSE: To prevent cavitation from occurring in a delivery section on the suction side in the opposite direction to a rotor in a vane pump. CONSTITUTION: The radius of a small circle part 32 on the forward suction 38 side in a cam ring 22 is made smaller than that of a small circle part 32 on the suction 39 side in the opposite direction to form a clearance L between a rotor 26 and the cam ring 22 in the delivery section 40 of an operating chamber Y on the suction 39 side in the opposite direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vane pump,
For example, the present invention relates to a power steering vane pump for reducing a steering force of a power steering of an automobile.

[0002]

2. Description of the Related Art A conventional vane pump as shown in FIG. 4 is known. Reference numeral 1 denotes a cam ring housed in a housing 2, wherein the cam ring 1 is a large circle portion 3
It has a cam surface 3 composed of a and a small circle portion 3b. The cam ring 1 accommodates a rotor 5 to which a vane 4 is attached so as to be retractable, and a pair of working chambers W and X are defined between the great circle portion 3a and the rotor 5, and these working chambers are Depending on the rotational position, it is divided into a pair of discharge sections 6 and 7 and a pair of suction sections 10 and 11. A pair of inhalation sections 1
The volumes of 0 and 11 and the discharge sections 6 and 7 are equal because the radii of the large circle portion 3a and the small circle portion 3b are constant. Both ends in the axial direction of the cam ring 1 are closed by a front plate (not shown) and a rear plate 8, respectively. An inlet passage (not shown) for guiding hydraulic oil is formed in the housing 2, and the inlet passage is formed continuously with the rear cover 8. The introduction flow passage 9 formed in the rear cover 8 is formed substantially perpendicular to the axis of the rotor 5, and bifurcates midway to introduce working oil into each of the working chambers W and X. When the rotor is rotated in the direction of arrow (A) into each of the working chambers W and X, the working oil is sucked by the pumping action of the suction sections 10 and 11 which is enlarged by the protrusion of the vane 4 from the rotor 5, and the introduction passage 9 is provided. To inhalation section 1
A forward suction port 12 that is sucked in the forward direction in 0 and a backward suction port 13 that is sucked in the reverse direction in the suction section 11 are open.

In this vane pump, the suction stroke and the discharge stroke are performed by one rotation of the rotor 5, and the working oil sucked into the suction section 10 is discharged from the discharge section 7 and sucked into the suction section 11. Is discharged from the discharge section 6.

[0004]

However, in such a vane pump, the hydraulic oil sucked into the suction section 10 on the side of the forward suction port by the pump action flows from the introduction flow path 9 to the forward suction port 12. Through this suction section 10
Since it is sucked into the inside in the forward direction, the flow path resistance is small due to the inertial force of the hydraulic oil, and the oil is smoothly sucked. On the other hand, the hydraulic oil sucked into the suction section 11 of the reverse suction port by the pumping action is sucked in the reverse direction from the introduction flow path 9 into the suction section 11 through the reverse suction port 13, so that the flow path resistance is reduced. Is large and is not inhaled smoothly.

Therefore, the discharge section 6 on the reverse inlet side
The amount of hydraulic oil carried in from the suction section 11 was smaller than that of hydraulic oil carried in from the suction section 10 to the discharge section 7 on the forward suction port side. Therefore, the rotor 5 is
When rotating at a high speed (8,000-9,000 rpm) at 500 rpm or more, cavitation occurred in the discharge section 6 on the reverse inlet side. That is, bubbles are generated in the hydraulic oil in the suction section 11 due to insufficient suction, and when the bubbles are pressurized and destroyed in the discharge section 6, vibration and noise occur in the vane pump, the vane 4, and the cam surface. There is a problem that the inner wall of No. 3 and the outer peripheral wall of the rotor 5 are corroded.

[0006]

In order to solve such a problem, the present invention provides a cam ring having a cam surface composed of a large circle portion and a small circle portion, and a rotor housed in the cam ring. And a pair of working chambers defined between the cam ring and the rotor, and an introduction flow path arranged substantially perpendicular to the axial direction of the rotor and bifurcating from the middle to introduce working fluid into each of the working chambers. And a forward suction port through which the working fluid is sucked forward into the one working chamber through the introduction passage by the rotation of the rotor, and a working fluid is sucked backward through the introduction passage into the other working chamber. In a vane pump having a reverse suction port, the radius of the small circle portion on the forward suction port side is smaller than the radius of the small circle portion on the reverse suction port side.

[0007]

When the rotor is rotated, the working oil sucked by the pump action into the suction section of the forward suction port side working chamber is
Since the fluid is sucked in the forward direction from the introduction passage into the suction section through the forward suction port, the flow path resistance is reduced due to the inertia force of the hydraulic oil, and the suction is smoothly performed. Since a gap L is formed between the rotor and the cam ring in the suction section of the chamber, the working oil corresponding to the gap is carried from the discharge section on the forward suction port side by the gap L. This carry-in portion compensates for the shortage of suction from the reverse suction port, so by rotating the rotor at a high speed of 7,500 rpm or more, the working chamber volume can be sufficiently filled even in this suction section and cavitation can be prevented. it can.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 21 is a housing for housing a cam ring 22, and this housing 21 rotatably supports a drive shaft 24 having a pulley 23 attached to one end thereof via a bearing 25. A rotor 26 is rotatably housed in the cam ring 22, and both ends of the cam ring 22 are closed by a front plate 27 and a rear plate 28. The cam ring 22 and the front plate 27 are housed in the housing 21, while the rear plate 28 seals the housing 21 from the outside as a rear cover. The rotor 26 is spline-fitted to the other end of the drive shaft 24.
An introduction channel 29 for guiding hydraulic oil is formed in the upper part of the housing 21, and the introduction channel 29 communicates with an introduction channel 29 formed in a rear plate 28 that seals the housing 21. As shown in FIG. 2, the introduction flow path 29 is formed from the upper part thereof to be substantially perpendicular to the axial direction of the rotor 26 and downward, and bifurcates in the middle thereof, and on the side surface of the cam ring 26 of the rear plate 28. It is open to. On the other hand, as shown in FIG. 3, a cam surface 33 composed of a large circle portion 31 and a small circle portion 32 is formed on the cam ring 22, and a vane 34 is attached to the rotor 26 so as to be able to come and go. Great circle 31
And a rotor 26 define a pair of discharge sections 36 and 37, and a small circle 32 and a rotor 26 define a pair of suction sections 40 and 41. When rotated in the direction B), the forward suction section 41 and the forward discharge section 37 constitute a forward working chamber Z, and the backward suction section 40 and the backward discharging section 36 form a backward working chamber Y. To configure,
A forward suction port 38 is opened in a suction section 41 of the working chamber Z through which the working oil flows in from one side 29a of the introduction channel 29 in the forward direction, and flows in the opposite direction from the other side 29b of the introduction channel 29. In the suction section 40 of the working chamber Y, the reverse suction port 39
Is open. Further, discharge ports (not shown) are opened in the discharge sections 37 and 36 of the respective working chambers Y and Z.

The inner peripheral wall of the small circle portion 32 on the reverse suction port 39 side is formed so as to be separated from the outer peripheral wall surface of the rotor 26 by a slight gap L from the inner peripheral wall of the small circle portion 32 on the forward suction port 38 side. ing. That is, the radius r ₁ of the small circular portion 32 on the forward suction port side is equal to the radius r ₂ of the small circular portion 32 on the reverse suction port side.
It has been made smaller.

Next, the operation will be described.

The rotational driving force of the engine rotates the rotor 26 via the pulley 23 and the drive shaft 24. When the rotor 26 rotates in the direction of the arrow (B) in FIG.
Through the suction chambers 41 and 40 of the working chambers Y and Z, respectively. Further, this hydraulic oil is discharged from the discharge section 37,
36, and is discharged from each discharge port and sent to an actuator (not shown). At this time, the working oil sucked into the suction section 41 is sucked from the one side 29a of the introduction flow passage 29 through the forward suction port 38, and thus is smoothly sucked by the inertia force of the working oil.
On the other hand, the suction section 40 of the working chamber Z on the side of the reverse suction port 39
Since a gap L is formed between the rotor 26 and the cam ring 22, the gap L allows the hydraulic oil for the gap to flow into the reverse suction section 40 from the discharge section 37 on the forward suction port 38 side. Be brought in. The carry-in amount compensates for the shortage of suction from the reverse suction port 39, so that even if the shortage of suction in the suction section 40 by rotating the rotor at a high speed of 7,500 rpm or more is sufficient, the working chamber Z
The volume can be filled, and cavitation can be prevented from occurring.

Therefore, even if the rotor 26 is rotated at a high speed of 7,500 rpm or more (8,000 to 9,000 rpm), the pumping action of the working chamber Y is not unreasonable and cavitation does not occur in the working chamber Y. As a result, vibration and noise due to cavitation are prevented, and the vane 34 and the great circle 3
The inner peripheral wall of No. 1 and the outer peripheral wall of the rotor 26 are not corroded.

[0014]

As described above, the present invention provides a cam ring having a cam surface having a large circle portion and a small circle portion, a rotor housed in the cam ring, and a space defined between the cam ring and the rotor. A pair of working chambers, an introduction flow path that is arranged substantially perpendicular to the axial direction of the rotor, branches into two branches from the middle, and introduces the working fluid into each of the working chambers, and the working fluid is introduced by the rotation of the rotor. A vane pump having a forward suction port that is sucked in a forward direction into the one working chamber through a passage, and a reverse suction port that sucks a working fluid in a reverse direction into the other working chamber through an introduction flow path; ,
Since the radius of the small circle on the forward suction port side is smaller than the radius of the small circle on the reverse suction port side,
When the rotor is rotated, the hydraulic oil that is sucked into the suction section of the forward suction port side working chamber by the pump action is sucked in the forward direction from the introduction passage through the forward direction suction port into this suction section, and its operation is performed. The flow path resistance is small due to the force of inertia of the oil, and the oil is smoothly sucked, while a gap L is formed between the rotor and the cam ring in the suction section of the reverse direction suction side working chamber.

Due to this gap L, the hydraulic oil for the gap is introduced from the discharge section on the forward suction port side into the suction section on the reverse suction port side, and due to this carry-in amount, the shortage of suction from the reverse suction port is caused. Is compensated for and the rotor is 7,500r.
It is possible to sufficiently fill the working chamber volume even in this suction section by rotating at a high speed of pm or more, and prevent cavitation from occurring. As a result, vibration and noise of the vane pump due to cavitation are prevented, and the vanes, the inner peripheral wall of the cam surface and the outer peripheral wall of the rotor are not corroded.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a vane pump according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

3 is a cross-sectional view taken along the line III-III in FIG.

FIG. 4 is a sectional view showing a main part of a conventional vane pump.

[Explanation of symbols]

22 cam ring 26 rotor 29 introduction passage 31 large circle portion 32 small circle portion 33 cam surface 36 discharge section (reverse direction) 37 discharge section (forward direction) 38 forward suction port 39 reverse suction port Y working chamber (reverse direction) Z) Working chamber (in the forward direction) r ₁ Radius of the forward suction port in the small circle part r ₂ Radius of the reverse suction port in the small circle part

Claims (1)

[Claims] 1. A cam ring having a cam surface composed of a large circle portion and a small circle portion, a rotor housed in the cam ring, a pair of working chambers defined between the cam ring and the rotor, and a rotor of the rotor. Introducing passages arranged substantially perpendicular to the axial direction and bifurcating from the middle to introduce the working fluid into each of the working chambers, and the working fluid is forwarded into the one working chamber through the introducing passages by the rotation of the rotor. In the vane pump, the vane pump is provided with a forward suction port for sucking into the other working chamber and a reverse suction port for sucking working fluid in the opposite direction into the other working chamber through the introduction flow path. The vane pump is characterized in that the radius of the portion is made smaller than the radius of the small circular portion on the reverse inlet side.