JPS6242153Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to a variable displacement vane pump having a movable ring movable in the radial direction within the inner hole of a pump housing and having variable discharge displacement.

<Prior art> In this type of variable displacement vane pump,
The fluid chamber formed between the inner peripheral wall of the pump housing and the outer periphery of the movable ring is divided into two, and an orifice is formed in the discharge passage communicating with one compartment, and the pressure on the downstream side of this orifice is transferred to the other compartment. By applying pressure to the chamber, the eccentricity of the movable ring is changed using the differential pressure before and after the orifice, and the flow rate of pressurized fluid supplied to the fluid equipment is controlled to be constant regardless of fluctuations in the rotational speed of the rotor. There is something. However, in cold regions where the temperature of the hydraulic oil of variable displacement vane pumps drops significantly, the density and viscosity of the hydraulic oil become extremely high, and even at low flow rates, a certain pressure difference occurs before and after the orifice, causing the amount of eccentricity of the movable ring. There was a problem in that the required discharge amount could not be secured because the amount was controlled to move to the low discharge side.

<Purpose of the invention> Therefore, the purpose of the present invention is to ensure a pump discharge flow rate even at low temperatures.

<Structure of the invention> The characteristic structure of the invention is that the member constituting the sealing part or the constriction part that divides the fluid chamber around the outer periphery of the movable ring into two chambers is made of a material that has a large shrinkage amount at low temperatures. The area of the communication passage between the fluid chambers is increased to maintain a constant supply flow rate even at low temperatures.

<Examples> Examples of the present invention will be described below based on the drawings. 1 and 2 show a variable displacement vane pump according to the present invention. The pump housing 10 of this pump includes a front housing 11
, guide housing 12, and rear housing 1
3 and a guide housing 12.
An inner hole 12a is formed in which a rotor 23 having a movable ring 21 and a number of vanes 22 is accommodated.

The movable ring 21 is an annular member having a predetermined diameter smaller than the diameter of the inner hole 12 a of the guide housing 12 .
a is housed so as to be movable in the radial direction, and forms a fluid chamber R between the peripheral wall of the inner hole 12 a and the outer periphery of the movable ring 21 . The rotor 23 is spline-fitted to one end of a rotating shaft 24 that is rotatably and liquid-tightly supported by the front housing 11. A pump chamber P is formed between the outer peripheries. The movable ring 21 is biased leftward in the figure by a flow rate adjustment spring 25 interposed between a screw member 30 disposed on the second right side of the guide housing 12 and the outer periphery of the movable ring 21. It is in contact with a screw 26 for regulating the maximum eccentricity disposed on the second left side of the housing 12 in the drawing. As a result, the movable ring 21 is eccentric to the rotor 23 by the maximum amount.

On the other hand, on the inner surface of the front housing 11,
A suction port 11a and a discharge port 11b are formed. The suction port 11a communicates with a suction passage 11c provided in the front housing 11 and the suction area of the pump chamber P, and the discharge port 11b communicates with the discharge area of the pump chamber P and the fluid chamber R.

Therefore, the elongated hole 11d provided on the inner surface of the front housing 11 and the elongated hole 14a provided on the inner surface of the pressure plate 14 have pivot shafts 27 extending in the axial direction.
Both ends are fitted. In addition, the movable ring 21
A hole 21b penetrating between both side surfaces is bored in the protrusion 21a protruding from the outer circumferential surface of the holder, and a pivot 27 is inserted through the hole 21b and is pivotably supported. A sealing member 31 whose one end abuts against the outer peripheral surface of the protrusion 21a is connected to the axial groove 1 of the guide housing 12.
2b, and performs a sealing action at the top of the protrusion 21a. The sealing member 31 is made of a fluorine-based plastic or the like, and has a coefficient of linear expansion larger than that of the ferrous metal material that constitutes the guide housing and the like. Further, a fitting recess 12b extending in the axial direction is formed in the lower peripheral wall of the inner hole 12a of the guide housing 12, and a gap adjustment member 28 is fitted and fixed in the fitting recess 12b. The gap adjusting member 28 slightly protrudes into the fluid chamber R, forms a constricted portion O between its inner surface 28a and the outer peripheral surface of the movable ring 21, and together with the sealing member 31, the fluid chamber R is divided into a first working chamber _r1 in which the discharge port 11b opens and a second working chamber _r2 in which the discharge hole 12c opens. Both of these working chambers r ₁ and r ₂ communicate with each other through the constricted portion O. Incidentally, instead of the sealing member 31, the gap adjusting member 28 may be made of a material with a large coefficient of linear expansion.

When the vane pump configured in this manner operates in a temperature range above normal temperature, the sealing member 31 expands and performs its original sealing action. When not driven, the movable ring 21 is eccentric by the maximum amount as shown in FIG.
When the rotor 23 integrated therewith rotates, the fluid sucked into the pump chamber P through the suction passage 11c and the suction port 11a is discharged as pressure fluid to the first action chamber r1 through the discharge port _11b .
Further, it flows into the second action chamber _r2 through the constriction part O, and is supplied to an appropriate fluid operating device through the discharge hole 12c and a discharge passage (not shown). During this time,
When the rotational speed of the rotating shaft 24 and the rotor 23 (pump rotational speed) increases and the amount of pressure fluid discharged to the first working chamber _r1 increases, a gap between the first working chamber _r1 and the second working chamber r2 _increases . The generated differential pressure causes the movable ring 21 to swing to the right in the second figure against the spring 25.
As a result, the amount of eccentricity of the movable ring 21 with respect to the rotor 23 decreases in accordance with the increase in differential pressure (increase in pump rotation speed), reducing the discharge amount per pump rotation, and the pump operates regardless of the increase in pump rotation speed. The amount of pressure fluid supplied to the equipment is controlled to be constant, and the required flow rate is discharged.

On the other hand, at low temperatures, the sealing member 3
1 contracts, a gap is formed at the sealing point, and a passage is formed that communicates the first working chamber _r1 and the second working chamber _r2 , so that it flows into the second working chamber _r2 through the constriction part O. In addition to the fluid, the second working chamber is supplied from the sealing member 35.
This results in fluid flowing into r ₂ . Although the viscosity of the fluid is high at low temperatures, the area of the passage connecting the first working chamber _r1 and the second working chamber _r2 increases due to the above-mentioned action, so the pressure difference before and after the constriction part increases the delivery flow rate. As a result, the movement of the movable ring toward the low discharge side is reduced, and the required flow rate is ensured.

<Effects of the invention> As described above, in the present invention, the sealing part or constriction part around the cam ring is made of a member that contracts at low temperatures, increasing the passage area that communicates the two fluid chambers at low temperatures, and reducing the constriction. Since the pressure difference between the front and rear parts is prevented from increasing due to the viscosity of the working fluid, there is an advantage that the required discharge amount can be secured even with a high viscosity working fluid at a low temperature.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a vane pump according to a first embodiment of the present invention, and FIG. 2 is a longitudinal sectional view taken along the line - in FIG. 1. 10...Pump housing, 11a...Suction port, 11b...Discharge port, 12a...Inner hole,
12c...Discharge hole, 21...Movable ring, 23...
...Rotor, 25...Spring, 27...Pivot,
28... Gap adjustment member, 28a... Inner surface, O...
... Throttle part, P... Pump chamber, R... Fluid chamber, r ₁ ,
r ₂ ...Action chamber, 31...Sealing member.

Claims (1)

[Scope of utility model registration request] A rotor with multiple vanes is housed inside a movable ring that is movable in the radial direction within the inner hole of the pump housing, and a spring is placed around the outer circumference of the movable ring to press the movable ring in the direction of increasing eccentricity. In a variable displacement vane pump made of
A seal portion and a constriction portion are provided to divide the fluid chamber on the outer periphery of the movable ring into two chambers, and a discharge port communicating with the discharge area of the pump chamber formed between the inner periphery of the movable ring and the outer periphery of the rotor is provided with the spring. One fluid chamber on the opposite side communicates with the other fluid chamber on the spring side, and the other fluid chamber on the spring side communicates with the discharge hole. A variable displacement vane pump characterized in that its constituent members are made of a material that contracts a large amount at low temperatures.