JP2526636Y2 - Flow control mechanism for power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to a flow control mechanism for controlling a supply flow rate of pressure hydraulic oil used in a power steering device provided in an automobile or the like.

<< Prior Art >> A hydraulic power steering device is generally of a hydraulic type. In this case, a vane pump is widely used as an oil pump as a hydraulic power source. Vane pumps are particularly suitable for this type of application because of their small size and durability.

Further, the hydraulic power steering apparatus for a vehicle is provided with a flow control mechanism. The function of the flow control mechanism is to apply a desired amount of pressure oil to the hydraulic circuit of this actuator regardless of the rotation speed of the oil pump and regardless of the pressure fluctuation in the hydraulic circuit of the actuator of the power steering device accompanying the steering operation. To supply. This is because the ratio of the steering assisting force generated by the actuator to the total steering force is determined according to the flow rate of the pressure oil supplied to the hydraulic circuit.

The flow control mechanism is basically configured for the purpose of supplying a predetermined constant flow of pressure oil. This is to stabilize the steering assisting force. However, since it is preferable to reduce the ratio of the steering assisting force when the vehicle is running at high speed, a flow control mechanism having a so-called flow-down characteristic for reducing the supply flow rate of hydraulic oil during high-speed running has been proposed. However, strictly changing the supply flow rate according to the vehicle speed requires a vehicle speed sensor and the like, which complicates the structure.
In many cases, the supply flow rate of the pressure hydraulic oil is changed according to the rotation speed of the oil pump in proportion to the engine rotation speed.

On the other hand, from the viewpoints of high reliability, simplification of an assembling process, space saving, and the like, which are particularly required for a power steering device for an automobile, the flow control mechanism is preferably incorporated in an oil pump.

<< Problems to be Solved by the Invention >> In view of the above circumstances, it is desirable to incorporate a flow control mechanism having a flow-down function into a vane pump for a power steering device of an automobile. Between the side plates,
A rotor having a plurality of vanes and a cam ring in which the tips of the vanes are inscribed must be provided, and an oil intake port and a discharge port must be provided). No flow control mechanism enabling the structure has been proposed.

Accordingly, an object of the present invention is to provide a flow control mechanism for a power steering device having a flow-down function and built in a vane pump.

<< Means for Solving the Problems >> In order to achieve the above object, a flow control mechanism for a power steering device according to the first invention of the present application is a flow control device for a power steering device which controls a discharge flow rate of an oil pump including a vane pump mechanism. A control mechanism, comprising: a first discharge passage having a first communication passage provided with an orifice that communicates a discharge port of the vane pump mechanism and a discharge port of the oil pump; and a differential pressure on both sides of the orifice. A spool valve that maintains a constant value, a second discharge passage that is provided in parallel with the first discharge passage, and has a second communication passage that communicates a discharge port of the vane pump mechanism and a discharge port of the oil pump, The vane pump is interposed in the second communication passage, is normally urged in a direction to open the second communication passage, and is introduced at one end thereof through a damper orifice. It is characterized in that a sub-spool vane back pressure mechanism is moved in a direction of closing the second communication passage in association with increases with increasing pump speed.

In a preferred embodiment, the damper orifice is formed of a material having a large coefficient of thermal expansion and is formed by a plug fitted to a side plate of the vane pump mechanism.

Further, a flow control mechanism for a power steering device according to the second invention of the present application is a flow control mechanism for a power steering device that controls a discharge flow rate of an oil pump including a vane pump mechanism, wherein a discharge port of the vane pump mechanism and the oil A first discharge passage having a first communication passage provided with an orifice, which communicates with a discharge port of the pump; a spool valve for maintaining a differential pressure on both sides of the orifice at a constant value; A second discharge passage provided in parallel with the discharge port of the vane pump mechanism and the discharge port of the oil pump; a fixed orifice for restricting and discharging the discharge pressure of the vane pump mechanism; and a part of the first discharge passage And is normally urged in a direction to open the second discharge passage, so that the post-throttle pressure of the fixed orifice and the first discharge A sub-spool that operates by a pressure difference from the discharge pressure of the passage, and moves in a direction to close the second discharge passage as the pressure difference increases with an increase in the pump rotation speed. .

<< Operation >> According to the first invention of the present application configured as described above, the first discharge passage supplies a substantially constant flow rate of hydraulic oil to the oil pump discharge port irrespective of the pump rotation speed, while the second discharge passage supplies second hydraulic oil to the oil pump discharge port. The discharge passage is closed at the time of high-speed rotation according to the pump rotation speed, and supplies the hydraulic oil only at the time of low-speed rotation, thereby performing flow control having good flow-down characteristics. Further, since the vane back pressure for operating the sub-spool for opening and closing the second discharge passage is introduced to the sub-spool valve through the damper orifice, stable operation of the sub-spool is obtained. Further, according to the present invention, since the damper orifice for introducing the back pressure of the vane is constituted by a plug formed of a material having a large coefficient of thermal expansion, the diameter of the orifice is reduced with an increase in the hydraulic oil temperature, and the sub-spool Is controlled stably from a low temperature to a high temperature.

According to the second invention of the present application, the differential pressure between the post-throttling pressure of the fixed orifice and the pump discharge pressure causes the sub-spool to operate so as to close the second discharge passage during high-speed rotation of the pump,
As a result, as in the case of the first invention, flow control having good flow-down characteristics is performed.

<< Example >> Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an oil pump for power steering provided with an embodiment of a flow control mechanism for a power steering device according to the first invention of the present application.

FIG. 1 shows the whole of the oil pump by reference numeral 10. The oil pump 10 has a housing composed of a front cover 12 and a rear cover 14. The side (right side in the drawing) from which the rotary shaft 16 of the pump protrudes is the front side of the oil pump 10.

The rear cover 14 accommodates a pump unit (also referred to as a cartridge) 18 configured as a vane pump, and incorporates a flow control mechanism according to the first invention of the present application.

The pump unit 18 includes a pair of front and rear side plates (a front side plate 20 and a rear side plate 22).
And a unit body integrally formed with a cam ring 24 sandwiched therebetween, and a rotor 26 disposed inside the unit body and carrying a vane 28.

The pump rotation shaft 16 is connected to the rotor 26. The pump rotation shaft 16 is rotatably supported by the front cover 12, while the pump unit 18 is fixed to the front cover 12 and covered by the rear cover 14.

As shown in FIGS. 2 and 3, the rotor 26 has a plurality of radial vane accommodation grooves 30 for accommodating and supporting the vanes 28 on its outer periphery.
When rotated, the respective vanes 28 slide into and out of the vane accommodating groove 30 with the side surfaces slidingly contacting the side plate and the leading ends slidingly contacting the cam surface (inner peripheral surface) of the cam ring 24. It rotates with the rotor 26.

The front and rear side plates 20, 22 have a cartridge inner chamber S
1 (the space between the rotor 26 and the cam ring 24 inside the cartridge 18) and the suction port 32 (FIG. 4) and the discharge port
(FIG. 1) is formed, hydraulic fluid is sucked in from the suction port 32 with the rotation of the rotor 26, and is discharged from the discharge port (hereinafter referred to as the cartridge discharge port) 34 of the cartridge 18. , A pump action occurs.

The cartridge discharge port 34 opens to a space S2 in the rear cover 14. Accordingly, since the pressure in the space S2 becomes equal to the cartridge discharge pressure when the oil pump 10 is operated, the space S2 is referred to as a "high-pressure chamber". On the other hand, the suction port 32 of the cartridge 18 communicates with a reservoir section 36 (FIG. 4) formed in the front cover 12, and the pressure of the reservoir section 36 is set to substantially the atmospheric pressure. .

As shown in FIG. 3, the bottom of the rotor 26 and the vane receiving groove 30 is a vane back pressure chamber 38. The front and rear side plates 20 and 22 are provided with vane back pressure groove chambers 40 and 42 formed as substantially annular grooves at positions communicating with the vane back pressure chamber 38. Through these vane back pressure grooves 40, 42, the rotor 2
The cartridge discharge pressure is introduced into the vane back pressure chamber 38 of 6,
Thereby, the vane 28 is biased in the projecting direction.

Here, referring to FIG. 2, the operation phase of the suction and discharge of the cartridge 18 will be described. This figure is II in Fig. 1.
FIG. 2 is a cross-sectional view taken along line -II, as viewed from the rear side of the oil pump 10. The rotor 26 rotates in the direction of arrow R in FIG. 2, and each vane 28 undergoes two suction strokes and two discharge steps during one rotation. In the figure, the left quadrant and the right quadrant are the suction areas, and the upper and lower quadrants are the discharge areas.

As shown in FIG. 4 (a cross-sectional view along the line IV-IV in FIG. 1), the vane back pressure groove chambers 40 and 42 of the side plates 20 and 22 have:
A throttle section 48 is provided at each boundary between the suction area portions 44a, 44b and the discharge areas 46a, 46b. And
Openings (not shown) for introducing the cartridge discharge pressure into the vane back pressure groove chambers 40 and 42 are provided in the left suction area portion 44a and the right suction area portion 44b, respectively.

Hereinafter, the operation of the throttle section 48 will be described. When the vane 28 moves into and out of the vane accommodating groove 30 with the rotation of the pump, the volume of the vane back pressure chamber 38 increases or decreases accordingly. Therefore, each vane back pressure chamber 38 sucks hydraulic oil from the vane back pressure groove chambers 40 and 42 when passing through the suction area, and flows into the vane back pressure groove chambers 40 and 42 when passing through the discharge area. Discharge hydraulic oil. Therefore, during the operation of the pump, the hydraulic oil constantly flows in the vane back pressure groove chambers 40 and 42 from the discharge region portions 46a and 46b to the suction region portions 44a and 44b in a flow rate proportional to the pump rotation speed. ing. When the flow of the hydraulic oil passes through the throttle section 48, a pressure difference is generated between the front and rear of the throttle section 48 due to the orifice effect. As described above, since the cartridge discharge pressure is introduced into the suction region portions 44a and 44b, the presence of the throttle portion 48 results in the discharge region portions 46a of the vane back pressure groove chambers 40 and 42. , 46b becomes greater than the cartridge discharge pressure by the differential pressure of the throttle portion 48, which increases according to the rotation speed of the pump. The pressure that changes in accordance with the pump rotation speed obtained in this manner is used in a flow control mechanism described below.

Next, the flow control mechanism incorporated in the oil pump 10 will be described.

In brief, the flow control mechanism includes a discharge passage disposed between the cartridge discharge port 34 and the oil pump discharge port 52 for supplying hydraulic oil from the former to the latter.
It is equipped with a system. One of the discharge passages is a first discharge passage configured to discharge a predetermined constant flow of hydraulic oil regardless of the pump rotation speed, and the other discharges the hydraulic oil when the pump rotation speed is low. However, the second discharge passage is configured such that the discharge amount is reduced or the discharge is stopped as the rotation speed increases.

First, the first discharge passage will be described below with reference to FIG. 1 and FIG. FIG. 5 is a sectional view taken along line VV in FIG.

The principle of operation of the first discharge passage is that a metering orifice is provided between the cartridge discharge port 34 and the oil pump discharge port 52, and the pressure difference on both sides of the metering orifice is controlled to a constant value by the spool valve. By doing
The amount of hydraulic oil flowing through the metering orifice is maintained at a constant amount, which has been widely used as an operating principle of a flow control mechanism.

In this embodiment, the function of the metering orifice is a fixed orifice 56 provided in a communication passage 54 formed in the front cover 12 as shown in FIG. One end of the communication passage 54 is open to the high-pressure chamber S2 in the rear cover 14, and thus communicates with the cartridge discharge port 34. The other end of the communication passage 54 on the side where the fixed orifice 56 is formed opens directly to the oil pump discharge port 52.

As shown in FIG. 1, the spool valve of the first discharge passage includes a spool 60 slidably fitted in a spool accommodating hole 58 formed in the front cover 12, and attaching the spool 60 to the left in the figure. And a biasing spring 62. In the spool housing hole 58, a first pressure chamber P1 is defined on the left side of the spool 60 in the figure, and a second pressure chamber P2 is defined on the right side in the figure.

The first pressure chamber P1 communicates with the high pressure chamber S2 in the rear cover 14, and thus communicates with the cartridge discharge port.
Further, the second pressure chamber P2 communicates with the oil pump discharge port 52 via a communication passage 64 formed in the front cover 12.
Therefore, the differential pressure between the respective pressures of the two pressure chambers P1 and P2 is always equal to the differential pressure on both sides of the fixed orifice 56.

Furthermore, the spool housing hole 58 has a drain port on its side.
65, the effective flow path cross-sectional area of the drain port 65 changes as the spool 60 moves in the axial direction. Further, by opening and closing the drain port 65, the high pressure chamber is opened.
The pressure of S2, that is, the pressure of the first pressure chamber P1 is controlled. The spool 60 moves so that the pressing force to the right in the drawing due to the differential pressure between the first and second pressure chambers P1 and P2 and the urging force to the left from the spring 62 in the drawing are balanced. spring
Since the urging force of the 62 only fluctuates little irrespective of the movement of the spool 60, the operation of the spool 60 eventually leads to the first
The differential pressure between the pressure chamber P1 and the second pressure chamber P2, and thus the differential pressure on both sides of the fixed orifice 56, is kept constant, whereby the hydraulic oil supplied to the pump discharge port 52 through the first discharge passage is discharged. The volume is kept constant.

Next, the second discharge passage will be described below with reference to FIG.

The principle of operation of the second discharge passage is that a communication path is provided between the cartridge discharge port 34 and the oil pump discharge port 52, and an open / close valve mechanism for opening and closing the communication path is provided in the communication path. By controlling the rotation speed of the pump according to the rotation speed, the communication path is fully opened in a low-speed rotation range of the pump, and is closed as the rotation speed increases.

The communication passage of the second discharge passage is a communication passage 68 formed in the front cover 12 shown in FIG. As shown in the drawing, a fixed orifice 69 for controlling the flow rate of hydraulic oil flowing when the valve opening mechanism is fully opened is formed at one end of the communication passage 68. The end on the fixed orifice 69 side is open to the high-pressure chamber S2 in the rear cover 14, and thus communicates with the cartridge discharge port. In addition, this communication passage 68
The other end is directly opened to the oil pump discharge port 52.

At the center of the communication passage 68, a sub-spool valve as an opening / closing valve mechanism of the communication passage 68 is provided. As shown in FIG. 5, the sub-spool valve includes a sub-spool 72 slidably fitted in a sub-spool receiving hole 70 formed in the front cover 12, and the sub-spool 72 is connected to the front side plate 20 ( (Upward in the figure). In the sub-spool receiving hole 70, a first pressure chamber p1 is defined above the sub-spool 72 in the figure, and a second pressure chamber p2 is defined below the sub-spool 72 in the figure.

The sub-spool 72 fully opens the communication passage 68 of the second discharge passage when it is located at the uppermost position in the sub-spool housing hole 70 in FIG. 68 is closed and finally closed.

The second pressure chamber p2 communicates with the oil pump discharge port 52 via a communication passage 76, so that the sub-spool 72 moves in the valve opening direction by the pressure of the oil pump discharge port 52 and the urging force of the spring 74. Has been energized.

On the other hand, the first pressure chamber p1 is provided with the vane back pressure groove chamber described above.
The pressures in the discharge area portions 40 and 42 are introduced. More specifically, this pressure is applied to two discharge area portions 46 of the vane back pressure groove chamber 40 formed in the front side plate 20.
The first and second pressure chambers p1 and 46b are introduced into the first pressure chamber p1 from the lower discharge area portion 46b in FIG.

As described above, this pressure is a pressure higher than the cartridge discharge pressure by the differential pressure generated in the throttle section 48, and the differential pressure generated in the throttle section 48 depends on the rotation speed of the oil pump 10. It will increase. Since the pressure in the first pressure chamber p1 urges the sub-spool 72 in the valve closing direction below in the figure, the second discharge passage is gradually closed as the pump rotation speed increases, thereby obtaining a flow-down characteristic. It has become.

In the present embodiment, the pressure introduction passage 78 is configured as a damper orifice. This is to stabilize the operation of the sub-spool 72, and thus to stabilize the flow-down characteristic and extend the life of the sub-spool valve. That is, the pressure in the discharge region of the vane back pressure groove chamber 40 formed in the side plate 20 fluctuates every time one vane 28 passes through the throttle portion 48 of the vane back pressure groove chamber 40, and accordingly, When the number of rotations of the pump is R (rpm) and the number of vanes is N, a periodic fluctuation of frequency f = R × N occurs. The pressure introducing passage 78 is formed as a damper orifice so that undesired vibration does not occur in the sub spool 72 due to the influence of the pressure fluctuation.

More specifically, a through hole is formed at a corresponding position of the front side plate 20, and a plug 80 having a damper orifice is fitted into the through hole. The size of the damper orifice is so small that undesired vibration does not occur in the sub-spool 72 and large enough that the follow-up of the sub-spool 72 to the pump rotation speed is not deteriorated.

However, needless to say, the optimal size of the damper orifice depends on the viscosity of the hydraulic oil, and the viscosity of the hydraulic oil is greatly affected by its temperature. In this embodiment, even if the oil temperature of the hydraulic oil changes over a wide temperature range during operation of the pump, the plug 80 and the side plate 20 on which the It is formed of a material having a larger coefficient of thermal expansion than the material (usually a steel-based material is used). Specifically, an aluminum material or a synthetic resin material may be used, and it is preferable to select a material having a thermal expansion coefficient of 2.0 × 10 ⁻⁵ / ° C. or more.

Because of this, when the temperature of the hydraulic oil rises, the diameter of the damper orifice is reduced by the expansion of the plug 80, compensating for the effect of the decrease in the viscosity of the hydraulic oil, and damping the damper orifice. The degree can be maintained in a suitable range.

Next, FIG. 6 is an exploded perspective view showing an embodiment of a flow control mechanism for a power steering device according to the second invention of the present application, and FIG. 7 is a sectional view of a sub-spool portion thereof.

The difference between the flow control mechanism for a power steering device of the second invention and the first invention shown in FIGS. 1 to 5 is that the sub-spool valve for opening and closing the second discharge passage is connected to the first discharge passage. And that the sub-spool valve is operated by the differential pressure between the post-throttling pressure of the fixed orifice and the pump discharge pressure. Other configurations are the same as those of the first invention. In FIGS. 6 and 7, members common to or corresponding to FIGS. 1 to 5 are denoted by the same reference numerals. , Overlapping description will be omitted.

As shown in FIG. 7, a sub-spool 92 is fitted in a sub-spool receiving hole 90 provided in the front cover 12 of the pump housing.
Is biased toward the side plate 20 (right side in the figure). A center hole 96 is formed in the sub-spool 92 in the axial direction, and the front end side (the right side in the figure) of the sub-spool 92 is provided with a pressure oil from a first pressure chamber P1 (see FIG. 1) of the pump. Is fed to the oil pump outlet 52 through the center hole 96.
(See FIG. 5). Therefore, this center hole 96
Is a part of the first discharge passage.

Further, the front cover 12 is provided with a second discharge passage 98 that opens to the rear end side of the sub spool 92. The second discharge passage 98 discharges the pressure oil from the first pressure chamber P1 when the sub-spool 92 is located at the right part of the sub-spool housing hole 90 as shown in the figure, but the sub-spool 92 moves to the left. When it moves to the opening, the opening is closed, and the discharge of the pressure oil is shut off.

The front side plate 20 has a fixed orifice 100
A part of the pressure oil in the first pressure chamber P1 (see FIG. 1) of the pump is narrowed through the fixed orifice 100, and the sub-spool 92 is passed through the post-throttle pressure introduction holes 102 and 104.
Is introduced on the back side b. Since the discharge pressure of the pressure oil from the first pressure chamber P1 acts on the front side f of the sub-spool 92,
The sub-spool 92 operates by a pressure difference between the discharge pressure and the post-throttle pressure of the fixed orifice 100.

When the rotational speed of the pump is low, the differential pressure is small, so that the sub-spool 92 is urged by the spring 94 to be at the right end of the sub-spool housing hole 90 as shown in the drawing, and the second discharge passage 98 is opened. Therefore, the pressure oil is discharged from both the center hole 96 (first discharge passage) of the sub spool 92 and the second discharge passage 98. When the pump rotation speed increases, the differential pressure increases, and the sub-spool 92 moves to the left, overcoming the bias of the spring 94, and reduces the opening area of the second discharge passage 98 to reduce the discharge amount. When the rotation speed further increases, the second discharge passage 98 is completely closed, and discharge is performed only in the first discharge passage.

In this manner, the opening and closing of the discharge passage by the sub-spool 92 is controlled by the differential pressure between the post-throttle pressure of the fixed orifice and the discharge pressure of the pump, and the flow-down characteristic is obtained as in the case of the first invention. . FIG. 8 shows the relationship between the number of revolutions and the number of pumps by the flow control mechanism for the power steering device according to the present invention. This diagram is the same in the case of the first invention.

<< Effects of the Invention >> As is clear from the above description, the flow control mechanism for a power steering device according to the first invention of the present application is a flow control mechanism for a power steering device that controls the discharge flow rate of an oil pump including a vane pump mechanism. A first discharge passage having a first communication passage provided with an orifice, which communicates a discharge port of the vane pump mechanism with a discharge port of the oil pump; and maintaining a constant value for a differential pressure on both sides of the orifice. A second discharge passage provided in parallel with the first discharge passage and having a second communication passage communicating the discharge port of the vane pump mechanism and the discharge port of the oil pump; and the second communication passage. And is normally urged in a direction to open the second communication passage, and is provided at one end thereof with a vane of the vane pump mechanism introduced through a damper orifice. A sub-spool that moves in a direction to close the second communication passage as the back pressure increases with an increase in the pump rotation speed, so that the first discharge passage has a substantially constant flow rate regardless of the pump rotation speed. While the hydraulic oil is supplied to the oil pump discharge port, the second discharge passage is closed at the time of high-speed rotation according to the pump rotation speed and supplies the hydraulic oil only at the time of low-speed rotation, whereby flow control having good flow-down characteristics is achieved. Done. Further, since the vane back pressure for operating the sub-spool for opening and closing the second discharge passage is introduced to the sub-spool valve through the damper orifice, stable operation of the sub-spool is obtained.

In the first invention, the damper orifice is
Since it is formed of a material having a large thermal expansion coefficient and is constituted by a plug fitted to the side plate of the vane pump mechanism, the orifice diameter is reduced with an increase in hydraulic oil temperature,
The operation of the sub-spool can be controlled stably from a low temperature to a high temperature.

Further, a flow control mechanism for a power steering device according to the second invention of the present application is a flow control mechanism for a power steering device that controls a discharge flow rate of an oil pump including a vane pump mechanism, wherein a discharge port of the vane pump mechanism and the oil A first discharge passage having a first communication passage provided with an orifice, which communicates with a discharge port of the pump; a spool valve for maintaining a differential pressure on both sides of the orifice at a constant value; A second discharge passage provided in parallel with the discharge port of the vane pump mechanism and the discharge port of the oil pump; a fixed orifice for restricting and discharging the discharge pressure of the vane pump mechanism; and a part of the first discharge passage And is normally urged in a direction to open the second discharge passage, so that the post-throttle pressure of the fixed orifice and the first discharge A sub-spool that operates in a direction that closes the second discharge passage as the pressure difference increases with an increase in the pump rotation speed. Due to the differential pressure between the post-pressure and the pump discharge pressure, the sub-spool operates so as to close the second discharge passage during high-speed rotation of the pump, thereby providing good flow-down characteristics as in the case of the first invention. Can be performed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an oil pump for power steering provided with an embodiment of a flow control mechanism for a power steering device according to the first invention of the present application, FIG. 2 is a sectional view taken along line II-II of FIG. 3 is a partially enlarged view of FIG. 2, FIG. 4 is a sectional view taken along line IV-IV of FIG. 1, FIG. 5 is a sectional view taken along line VV of FIG.
FIG. 6 is an exploded perspective view showing an embodiment of a control mechanism for a power steering device according to the second invention of the present application, FIG. 7 is a sectional view of a sub-spool portion thereof, and FIG. It is the diagram which showed the relationship between the pump rotation speed and the quantity by the flow control mechanism for apparatus. 10 ... Oil pump, 18 ... Pump unit (vane pump mechanism), 20 ... Front side plate, 34 ... Cartridge discharge port (discharge port of vane pump mechanism), 52 ...
... oil pump discharge port, 54 ... first communication passage, 56 ... orifice, 60 ... spool, 68 ... second communication passage, 72 ... sub-spool, 78 ... pressure introduction passage (damper orifice), 80 ... plug, 92 ... sub-spool, 96 ... center hole (first discharge passage), 98 ... second discharge passage, 100 ... fixed orifice.

Claims (3)

(57) [Scope of request for utility model registration] 1. A flow control mechanism for a power steering device for controlling a discharge flow rate of an oil pump including a vane pump mechanism, wherein an orifice is provided for communicating a discharge port of the vane pump mechanism with a discharge port of the oil pump. A first discharge passage having a first communication passage formed therein; a spool valve for maintaining a differential pressure on both sides of the orifice at a constant value; and a discharge port of the vane pump mechanism provided in parallel with the first discharge passage. A second discharge passage having a second communication passage communicating with the discharge port of the oil pump; and a second discharge passage interposed in the second communication passage, which is normally urged to open the second communication passage, and has one end thereof. The sub-vane moves in a direction to close the second communication passage as the vane back pressure of the vane pump mechanism introduced through the damper orifice increases with an increase in pump rotation speed. A flow control mechanism for a power steering device, comprising: a spool. 2. The power steering system according to claim 1, wherein said damper orifice is made of a material having a large thermal expansion coefficient and is formed of a plug fitted to a side plate of said vane pump mechanism. Flow control mechanism for equipment. 3. A flow control mechanism for a power steering device for controlling a discharge flow rate of an oil pump including a vane pump mechanism, wherein an orifice is provided for communicating a discharge port of the vane pump mechanism with a discharge port of the oil pump. A first discharge passage having a first communication passage formed therein; a spool valve for maintaining a differential pressure on both sides of the orifice at a constant value; and a discharge port of the vane pump mechanism provided in parallel with the first discharge passage. A second discharge passage communicating with a discharge port of an oil pump; a fixed orifice for restricting and passing a discharge pressure of the vane pump mechanism; and a center hole forming a part of the first discharge passage. (2) It is urged in a direction to open the discharge passage, and is operated by a differential pressure between the post-throttle pressure of the fixed orifice and the discharge pressure of the first discharge passage. Power steering device for a flow control mechanism, characterized in that a sub-spool moving in the direction of closing the second discharge passage with the increases with increasing degree.