JPH0226715B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vane pump used as a hydraulic power source for a power steering device.

As a conventional vane pump, there is one shown in FIG. 1, for example. To explain this, reference numeral 1 denotes a housing having an inlet 2 for oil, which is a working fluid, and an inlet passage 3 continuing therefrom. A cam ring 4 is positioned and installed within the housing 1, and forms a suction chamber 5 between the cam ring and the inner circumference of the circular notch of the housing 1. Further, a rotor 7 rotatably driven by a shaft 6 is accommodated in the elliptical notch of the cam ring 4. The rotor 7 has slots extending radially on the outer peripheral surface, and vanes 10 that come and go in contact with and follow the inner peripheral surface of the cam ring 4, that is, the cam surface, are fitted into the slots, and the vanes 10 are inserted between adjacent vanes 10. A working chamber 9 for working fluid is formed.

In a vane pump with such a configuration, oil, which is the working fluid, is supplied from a reservoir tank (not shown).
A suction passage 3 is introduced from the suction port 2 into the suction chamber 5 . The oil introduced into the suction chamber 5 moves as the rotor 7 rotates in the counterclockwise direction, and is taken into each working chamber 9 in the cam ring 4 through the suction port 8. The oil in this work chamber 9 is
The work chamber 9 is pressurized by the change in volume between the vanes 10 as the rotor 7 rotates, and is discharged from a discharge port (not shown).

A portion of the discharged oil is returned to the suction passage 3 via a flow control valve 11 interposed between the discharge port and a discharge port (not shown). In this way, oil at a constant discharge pressure is led out to the discharge port.

By the way, in the case of the vane pump that operates as described above, the oil sucked in from the suction port 2 and the oil returned from the flow control valve 11 meet at the suction passage 3 at a substantially right angle, and then this is It joins the oil moving counterclockwise in the chamber 5.

However, at this time, the oil sucked in from the suction port 2 and the oil returned from the flow control valve 11 meet in the suction passage 3, but in the same way, the streamline of the oil flowing counterclockwise and the suction passage 3 The streamlines of the oil supplied from the two are substantially orthogonal to each other. That is, oil from the suction passage 3 joins the oil in the suction chamber 5 in a direction perpendicular to it. As a result, near the bend 12 where the oil streamline from the suction passage 3 is deflected, the second
As shown in the figure, a vortex 13 of oil is generated, which may generate bubbles, resulting in the so-called cavitation phenomenon.

Therefore, for example, as in the technique described in Japanese Utility Model Application Publication No. 56-124288, a flow dividing protrusion is provided on the outer peripheral surface of the cam ring facing the suction passage, thereby dividing the oil evenly into two on both sides of the suction chamber. However, since the suction passage is connected to the suction chamber from a direction perpendicular to the axis, there is a concern that swirling currents and accompanying cavitation may occur near the connecting point (merging portion).

Furthermore, as in the technique described in Japanese Utility Model Publication No. 43-5248, a technique has been proposed in which the suction passage is connected in the tangential direction of the suction chamber; Because the oil is uniform, the flow rate of oil drawn into the suction port far from the suction port is slower than that drawn from the suction port closer to the suction port, resulting in poor suction efficiency and an imbalance between each work chamber. This may cause the oil ejected from the outlet to pulsate or generate abnormal noise.

The present invention was made in order to improve the problems with the conventional vane pump, and it prevents the occurrence of cavitation in the suction passage and, in particular, supplies working fluid from the suction chamber to each suction port in a well-balanced manner. Therefore, the present invention provides a vane pump that can advantageously solve the above-mentioned problems.

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows a vane pump according to the present invention, in which the same parts as shown in FIG. 1 are given the same reference numerals. In Figure 3, 2a
2 is an oil suction port, and this suction port 2a intersects a relatively long suction passage 3a to the suction chamber 5 at an acute angle in the suction chamber 5 direction. Further, the suction passage 3a intersects the annular suction chamber 5 in a tangential direction.

According to this configuration, the oil sucked from the suction port 2a gently merges with the streamline of the oil flowing back from the flow control valve 11, and the merged oil flows into the long suction passage 3a.
By passing through the air, it receives a rectifying effect and prevents turbulence. The rectified oil then gently merges in a tangential direction with the streamline of the oil circulating in the suction chamber 5, completely preventing the generation of vortices at the merged portion. In this way, the generation of bubbles is eliminated, and the so-called cavitation phenomenon can be completely prevented.

On the other hand, the center of the suction chamber 5 and the center of rotation of the rotor 7 are slightly offset from each other, so that the cross-sectional area of the suction chamber 5 varies from the suction port 8 on the upstream side to the suction port 8 on the downstream side. It is formed so that it gradually becomes smaller towards the vicinity.

By doing this, a part of the oil introduced into the suction chamber 5 from the suction passage 3a is sucked from the suction port 8 on the upstream side into the working chamber 9 corresponding to the suction port 8. suction port 8
The amount of oil in the suction chamber 5 in the vicinity decreases and the flow velocity also decreases, but since the cross-sectional area of the lower suction chamber 5 is smaller than the cross-sectional area of the upstream suction chamber 5, the downstream suction The flow rate of oil supplied from the port 8 to the working chamber 9 corresponding to the suction port 8 is prevented from decreasing. Therefore, the energy of the oil supplied to each suction port 8, 8 on the upstream side and downstream side becomes equal, and is supplied in a well-balanced manner. In this way, oil is discharged from the two working chambers 9 at the same discharge pressure, and a balanced and stable assisting force for power staying and other load control pressures can be obtained.
The occurrence of pulsations, abnormal noises, etc. due to the discharge pressure difference between the two working chambers 9 can also be effectively prevented.

As explained above, according to the present invention, the streamlines of the working fluid drawn into the annular suction chamber intersect in the same direction and substantially tangentially with respect to the streamlines of the working fluid flowing through the suction chamber. In addition, the cross-sectional area of the suction chamber is formed so that it gradually decreases from the vicinity of the confluence with the suction passage toward the suction port on the upstream side and the suction port on the downstream side. In addition to preventing the occurrence of cavitation, the working fluid is supplied from the suction chamber to each suction port in a well-balanced manner, and the oil discharged from the discharge port does not cause pulsation or abnormal noise, and its operation is maintained. This provides the advantage of stabilizing power steering control using oil pressure.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional vane pump, FIG. 2 is an explanatory view showing the state of vortex generation in its main parts, and FIG. 3 is a sectional view of the vane pump of the present invention. 3, 3a... Suction passage, 5... Suction chamber, 8...
Inhalation port.

Claims (1)

[Claims] 1. The streamlines of the working fluid drawn from the outside through the suction passage into the annular suction chamber in which the plurality of suction ports are opened are substantially in the same direction with respect to the streamlines of the working fluid flowing through the suction chamber. The suction passage and the suction chamber are communicated so as to intersect in tangential directions, and the cross-sectional area of the suction chamber is directed from near the confluence with the suction passage toward the upstream suction port and the downstream suction port. A vane pump characterized in that the vane pump is formed to gradually become smaller as the size increases.