JPH0417834Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a vane pump used in a power steering device and the like.

<Prior art> Generally, such vane pumps have a plurality of vanes on the outer periphery of a rotor rotatably disposed inside a cam ring, the vanes slidingly contacting the inner cam surface of the cam ring, and the rotor is rotatably supported by a pump housing. It is rotated by an axis. As the rotor rotates, discharged pressure oil is introduced into back pressure chambers provided at the backs of the plurality of vanes, thereby pressing the tips of the vanes against the inner circumferential cam surface of the cam ring.

<Problems to be Solved by the Invention> Self-excited vibrations occur because the vane slides on the cam ring and rotates at high speed.

If the bearing that supports the rotating shaft is a ball bearing, this self-excited vibration can be absorbed to a value that does not pose a practical problem, but if it is a sliding bearing, the absorption effect is small and it may cause unpleasant noise. .

<Means for Solving the Problems> The present invention suppresses the occurrence of self-excited vibration by randomly inserting fine lines under certain conditions on the cam surface of the cam ring that slides on the vane.

<Function> When the vanes are in sliding contact with the cam inside the rotor and rotating, the oil stagnant in the randomly provided minute streaks acts as a damper with little directionality against the vanes and improves lubricity. to suppress self-excited vibration.

<Examples> Examples of the present invention will be described below based on the drawings. In FIGS. 1 and 2, 10 is a pump housing, and a cam ring 12 is provided in a hollow chamber 11 formed in this pump housing 10, and a pair of side plates 1 are provided on both sides of this cam ring 12.
3 and 14 are arranged.

Further, inside this cam ring 12, a rotor 16 is fixed by spline engagement to a rotating shaft 15 which is supported on the pump housing 10 by a sliding bearing 20. A vane 17 is held in each of the plurality of vane holding grooves 16a. A back pressure chamber 16b communicating with the vane holding groove 16a is formed at the back of each vane 17, and the discharge chamber 22 is communicated with the back pressure chamber 16b via an annular groove 30 and a communication hole 31. As a result, the vane 17
The tip 1 of the vane 17 is pressed toward the inner circumferential surface of the cam ring 12 by the pressure fluid supplied to the tip 1 of the vane 17.
7a is in sliding contact with the inner peripheral cam surface 12a of the cam ring 12. As shown in FIG. 3, fine lines 21 are randomly provided on the cam surface 12a over the entire surface. As shown in FIG. 4, the streaks 21 vary randomly in the range of 2 to 10 μm even in depth α, and are irregularly formed both in the circumferential direction and in the radial direction. Further, the area ratio occupied by the stripes 21 on the cam surface is 10% to 80%.

Each back pressure chamber 16b is provided with a spring member 32 made of a shape memory alloy, and when the oil is at a low temperature, the spring member 32 expands and pushes the vane 17 toward the inner cam surface 12.
It has a spring action to press against the vane 17, and when the oil is at high temperature, it contracts and prevents the spring force from acting on the vane 17.
It has the property of avoiding repeated loads due to the upper and lower parts of the vane 17.

Inside the cam ring 12, a cam ring 1 is provided.
A suction area and a discharge area are formed by the shape of the inner circumferential surface of 2, and the absorption area is communicated with the outer circumference of the cam ring 12 via the suction port 18 to be supplied with fluid from the tank T, and the discharge area is the suction area. It communicates with an unillustrated discharge port via a discharge port 19, a discharge chamber 22, and a flow rate control valve 25.

Next, the operation will be explained based on the above-described configuration. When the rotor 16 is rotated by the rotating shaft 15, the vane 17 is pressed against the cam surface 12a and rotates while sliding. During this rotation, vane 1
7 is the vane 1 due to the damping effect based on the viscosity of the pressurized oil staying in the random streaks 21.
Absorbs 7 self-excited vibrations. The absorption of the self-excited vibration is more effective when the stripes 21 are random in the depth direction, the circumferential direction, and the radial direction. Also, if the occupied area ratio of the streaks 21 is small, the damping effect will be small, and if it is too large, the cam surface will be subject to severe wear, so a range of 10% to 80% is desirable. Further, the depth α of the line 21 may be in a range in which a squeezing effect can be theoretically expected, but in order to obtain a greater damping effect and prevent wear of the cam surface, α is desirably about 2 to 10 μm or less.

<Effects of the Invention> As described above, the vane pump of the present invention absorbs the self-excited rocking motion generated in the vane 17 by the streaks 21 formed on the cam surface even when the rotating shaft 15 is supported by a sliding bearing.

That is, in FIG. 5, when the rotating shaft 15 is supported by a ball bearing, the self-excited vibration is A, but if it is a sliding bearing, it becomes large as B, but in this invention, due to the action of the line 21, the self-excited vibration is C. Thus, it can be reduced to the same level as A or less.

The present invention expands the scope of use of sliding bearings on the rotating shaft of vane pumps, making it possible to make vane pumps smaller and at higher rotational speeds.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a sectional view of a vane pump, FIG. 2 is a sectional view taken along the line - in FIG. 1, FIG. 3 is a sectional view of a cam ring, and FIG. FIG. 5 is a diagram comparing the performance of the present invention. 10...Pump housing, 11...Hollow chamber,
12... Cam ring, 13, 14... Side plate, 15... Rotating shaft, 16... Rotor, 16b
... Back pressure chamber, 17 ... Vane, 21 ... Line provided on the cam surface.

Claims (1)

[Scope of utility model registration request] A plurality of vanes that slide on the inner cam surface of the cam ring are held on the outer periphery of a rotor rotatably disposed inside the cam ring, and the pressurized oil after being discharged is discharged into a back pressure chamber provided at the back of the plurality of vanes. In the vane pump, the cam surface of the cam ring that contacts the vane has a depth of 2 to 10 μmm.
A vane pump characterized by large random stripes with an occupied area ratio of 10% to 80%.