JP2001184125A - Flow rate controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved flow rate controller capable of controlling flow down. SOLUTION: A spool valve 15 is stored in a spool valve storing hole 5 so as to be optionally slid and the hole 5 is divided into a 1st pressure room 16 and a 2nd pressure room 17. A lead passage 20 and a drain passage 19 that communicate with a discharge passage 8 through a control orifice 10 are opened in the 1st pressure room 16 and the pressure of the passage 8 is led into the 2nd pressure room 17. A 2nd orifice 45 is arranged on the upstream side of the control orifice 10. The control orifice 10 is constituted of a main orifice 11 and a sub-orifice 12. The flow rate controller is also provided with a sub- spool valve 46 for controlling the open/close of the sub-orifice 12 in response to the back-and-force differential pressure of the 2nd orifice 45 and increasing the opening area of the 2nd orifice 45 after closing the sub-orifice 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a power steering device of an automobile and the like, and controls a flow rate of a pressure working fluid supplied from a power source to an actuator of the power steering device to a predetermined flow rate. About.

[0002]

2. Description of the Related Art In a power steering apparatus which assists manual steering torque using a fluid as a working medium, a pump driven by an internal combustion engine mounted on a vehicle is used as a power source for supplying a working fluid to the power steering apparatus. Is often applied. However, in general, it is desired that the power steering device be able to acquire sufficient steering assisting force when the vehicle is running at a low speed or at a stop, in other words, when the internal combustion engine is driven at a low speed. At the time of rotation drive, from the viewpoint of steering stability,
Does not require much steering assistance. Therefore, a power source whose pump output increases in proportion to the rotation speed of the internal combustion engine cannot be applied as it is.

Therefore, usually, the power steering device controls the flow rate of the working fluid supplied to the power steering device from a pump so that a sufficient power steering operation can be performed in the idling or low rotation range of the internal combustion engine. When the rotation speed of the internal combustion engine is increased to some extent, the flow rate is limited by the control orifice, and a flow rate control device for returning excess fluid to the reservoir is applied.

As this type of flow control device, for example, Japanese Patent Application Laid-Open No. H11-78927 discloses that a spool valve is slidably accommodated in a spool valve accommodating hole, and a first pressure chamber and a first pressure chamber are defined in the spool valve accommodating hole. The first pressure chamber has an introduction passage communicating with the discharge passage via a control orifice and a drain passage communicating with the low pressure side. The second pressure chamber has a pressure of the discharge passage. And a control spring for biasing the spool valve toward the first pressure chamber. The control spring guides the required flow rate of the working fluid from the introduction passage to the discharge passage via the control orifice. There is disclosed a flow rate control device that recirculates water to a drain passage that is opened and closed by movement of a spool valve.

[0005] The flow control device has a second orifice provided upstream of the control orifice.
By providing a sub-spool valve that responds to the differential pressure across the orifice and reducing the opening area of the control orifice by the operation of the sub-spool valve, the rotation speed of the internal combustion engine increases to some extent and the operation moves from the introduction passage to the drain passage. If the fluid increases, reduce the control flow further,
So-called flow-down control is possible.

[0006]

Since the second orifice is provided on the upstream side of the control orifice, the whole amount of the fluid flowing back to the drain passage passes through the second orifice. Since the opening area of the second orifice is fixed, when the working fluid flowing back to the drain passage passes through the second orifice, the second orifice becomes a flow resistance and the internal pressure of the pump rises, thereby reducing the operating efficiency of the pump. There is a risk of lowering.

The present invention has been devised in view of such a conventional situation, and provides an improved flow control device capable of performing a flow-down control without increasing the internal pressure of the pump to lower the pump efficiency. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a spool valve slidably received in a spool valve receiving hole, and defines a first pressure chamber and a second pressure chamber in the spool valve receiving hole. An introduction passage and a drain passage communicating with the discharge passage through a control orifice are opened in the first pressure chamber, and a pressure in the discharge passage is introduced into the second pressure chamber and the spool valve is biased toward the first pressure chamber. A control spring that accommodates the required flow rate of the working fluid from the introduction path to the discharge path via the control orifice, while returning excess fluid to the required flow rate to the drain path that is controlled to open and close by movement of the spool valve. In the flow control device, a second orifice is provided upstream of the control orifice, and an opening area of the control orifice is controlled in response to a differential pressure across the second orifice. And are a configuration in which a sub-spool valve to increase the opening area of the second orifice when the opening area of the control orifice is reduced.

According to a second aspect of the present invention, a spool valve is slidably housed in a spool valve housing hole, and the spool valve housing hole is defined by a first pressure chamber and a second pressure chamber. An introduction passage and a drain passage communicating with the discharge passage through the control orifice are opened in the first pressure chamber, and the pressure in the discharge passage is introduced into the second pressure chamber and the spool valve is biased toward the first pressure chamber. A control spring is accommodated, and the required flow rate of the working fluid is guided from the introduction path to the discharge path via the control orifice, and excess fluid corresponding to the required flow rate is returned to the drain path controlled to be opened and closed by the movement of the spool valve. In the flow control device, a second orifice is provided upstream of the control orifice, and the control orifice is arranged in parallel with the main orifice. And a sub-spool valve that controls opening and closing of the sub-orifice in response to the differential pressure across the second orifice and increases the opening area of the second orifice after the sub-orifice is closed. It is.

According to a third aspect of the present invention, in the configuration of the first or second aspect, the control orifice is formed in a shaft portion of a connector having a discharge passage, and a sub-spool valve is provided in the connector. The second orifice is slidably fitted to the shaft, and the second orifice is formed on the outer peripheral side of the sub-spool valve.

According to a fourth aspect of the present invention, in the configuration of the third aspect, one end of the sub-spool valve is inserted so as to be able to protrude and retract into a damper chamber provided in the connector.

According to a fifth aspect of the present invention, in the configuration of the third aspect, the second orifice is formed between a baffle member provided on a shaft portion of the connector and an outer periphery of the sub-spool valve. Configuration.

In such a configuration, the working fluid discharged from the pump is guided into the first pressure chamber via the introduction passage. The working fluid led into the first pressure chamber is the second working fluid.
The second orifice, which occurs only when the flow restricts through the control orifice through the orifice and passes through the control orifice and when the drain passage is opened by the movement of the spool valve based on the differential pressure across the control orifice, Through the drain passage to the pump suction chamber and the excess fluid escaping to the reservoir.

Thus, a required amount of working fluid is guided from the discharge passage to the actuator under the restriction of the control orifice. For example, in a power steering device, a necessary steering assist force is obtained.

At this time, when the flow rate of the hydraulic oil guided into the first pressure chamber is small, the spool valve is in a position biased toward the first pressure chamber by a spring force of a control spring attached thereto. The drain passage is closed, and the flow rate of the working fluid passing through the second orifice is small.
Since the differential pressure across the orifice is small, the sub-spool valve does not reduce the opening area of the control orifice, and the spool valve moves and controls the flow rate by balancing the differential pressure across the control orifice with the spring force of the control spring. When the flow rate of the working fluid guided into the first pressure chamber increases, the differential pressure across the control orifice increases, so that the spool valve moves against the spring force of the control spring to open the drain passage and As the differential pressure across the second orifice increases, the sub-spool valve reduces the opening area of the control orifice, and the spool valve moves and balances the flow rate due to the balance between the differential pressure across the control orifice and the spring force of the control spring. .

More specifically, when the flow rate of the hydraulic oil guided into the first pressure chamber is small, the spool valve is located at a position biased toward the first pressure chamber by the spring force of a control spring attached thereto. The drain passage is closed. Also, the flow rate of the working fluid passing through the second orifice is small,
Since the differential pressure across the second orifice is small, the sub-spool valve does not reduce the opening area of the control orifice and does not increase the opening area of the second orifice. For this reason, the spool valve moves by the balance between the differential pressure across the control orifice and the spring force of the control spring, and the flow rate passing through the control orifice is controlled to the flow rate indicated by AB in FIG.

When the flow rate of the working fluid guided into the first pressure chamber increases, the differential pressure across the control orifice increases, so that the spool valve moves against the spring force of the control spring to open the drain passage. . In this state, when the differential pressure across the second orifice is equal to or less than a predetermined value, the sub-spool valve does not reduce the opening area of the control orifice and does not increase the opening area of the second orifice. As a result, the spool valve moves due to the balance between the differential pressure across the control orifice and the spring force of the control spring, and the flow rate passing through the control orifice is controlled to a constant flow rate (Q1) shown by BC in FIG. .

Next, when the flow rate of the working fluid passing through the second orifice increases, the sub-spool valve moves due to the differential pressure across the second orifice and gradually reduces the opening area of the control orifice. Is substantially reduced. by this,
The spool valve is moved by the balance between the pressure difference between the front and rear of the control orifice and the spring force of the control spring whose opening area is substantially reduced, and the flow rate passing through the control orifice is a constant flow rate shown by BC in FIG. C limited from Q1)
The flow rate is controlled to be indicated by -D. When the sub-spool valve reduces the opening area of the control orifice to a predetermined size, the sub-spool valve increases the opening area of the second orifice.

After the sub-spool valve reduces the opening area of the control orifice to a predetermined size, the spool valve moves due to the balance between the differential pressure across the control orifice and the spring force of the control spring, and passes through the control orifice. The flow rate is controlled to a constant flow rate (Q2) after D in FIG.
Thus, the working fluid guided from the discharge passage to the actuator is flow-down controlled. After the sub-spool valve reduces the opening area of the control orifice to a predetermined size, the state where the opening area of the second orifice has increased is continued.

Here, in the present invention, the opening area of the control orifice is controlled in response to the pressure difference between the front and rear of the second orifice, and when the opening area of the control orifice is reduced, the opening of the second orifice is reduced. The configuration is such that a sub-spool valve for increasing the opening area is provided. For this reason, when the opening area of the control orifice is reduced and the flow rate of the working fluid returning to the drain passage increases, the opening area of the second orifice increases, so that the flow resistance by the second orifice is minimized. The working fluid that flows back to the drain passage through the second orifice flows smoothly without being subjected to the flow resistance by the second orifice.
Thus, the internal pressure of the pump does not increase, and the operating efficiency of the pump does not decrease.

Therefore, an improved flow control device capable of flow-down control without lowering the pump efficiency due to an increase in the internal pressure of the pump can be obtained.

According to a second aspect of the present invention, the control orifice comprises a main orifice and a sub-orifice arranged in parallel with the main orifice, and the sub-orifice responds to a differential pressure across the second orifice. And a sub-spool valve for increasing the opening area of the second orifice after the sub-orifice is closed. For this reason, when the flow rate of the hydraulic oil guided into the first pressure chamber is small, the spool valve is moved by the spring force of the control spring attached to the spool valve.
Since the drain passage is closed at the position urged toward the pressure chamber, the flow rate of the working fluid passing through the second orifice is small, and the differential pressure across the second orifice is small, the sub-spool valve is controlled. Without closing the sub-orifice of the orifice, the spool valve moves and controls the flow rate by balancing the differential pressure across the control orifice and the spring force of the control spring. When the flow rate of the working fluid guided into the first pressure chamber increases, the differential pressure across the control orifice increases, so that the spool valve moves against the spring force of the control spring to open the drain passage and As the differential pressure across the second orifice increases, the sub-spool valve closes the sub-orifice of the control orifice, and the spool valve moves and balances the flow rate by balancing the differential pressure across the control orifice with the spring force of the control spring. .

More specifically, when the flow rate of the hydraulic oil guided to the first pressure chamber is small, the spool valve is located at a position biased toward the first pressure chamber by the spring force of a control spring attached thereto. The drain passage is closed. Further, since the flow rate of the working fluid passing through the second orifice is small and the differential pressure across the second orifice is small, the sub-spool valve does not close the sub-orifice of the control orifice and reduces the opening area of the second orifice. There is no increase. For this reason, the spool valve moves by the balance between the pressure difference between the front and rear of the control orifice and the spring force of the control spring, and the flow rate passing through the control orifice is represented by AB in FIG.
Is controlled to the flow rate indicated by.

When the flow rate of the working fluid introduced into the first pressure chamber increases, the differential pressure across the control orifice increases, so that the spool valve moves against the spring force of the control spring to open the drain passage. . In this state, when the differential pressure across the second orifice is equal to or less than a predetermined value, the sub-spool valve does not close the sub-orifice of the control orifice and does not increase the opening area of the second orifice. As a result, the spool valve moves due to the balance between the differential pressure across the control orifice and the spring force of the control spring, and the flow rate passing through the control orifice is controlled to a constant flow rate (Q1) shown by BC in FIG. .

Next, when the flow rate of the working fluid passing through the second orifice increases, the sub-spool valve moves due to the differential pressure across the second orifice and gradually closes the sub-orifice, thereby passing through the control orifice. The working flow is substantially reduced. When the sub-orifice is closed, the working fluid passes only through the main orifice. Thereby, the spool valve moves by the balance between the differential pressure across the control orifice and the spring force of the control spring, the opening area of which is substantially reduced,
The flow rate passing through the control orifice is controlled from a constant flow rate (Q1) indicated by BC in FIG. 3 to a flow rate indicated by CD limited. When the sub-spool valve closes the sub-orifice of the control orifice,
Increase the opening area of the orifice.

After the sub-spool valve closes the sub-orifice of the control orifice, the spool valve moves by the balance between the front-rear differential pressure of the control orifice, which is only the main orifice, and the spring force of the control spring, and passes through the control orifice. The flow rate to be changed is a constant flow rate (Q
Controlled in 2). Thus, the working fluid guided from the discharge passage to the actuator is flow-down controlled. Further, after the sub-spool valve closes the sub-orifice of the control orifice, the state where the opening area of the second orifice has increased continues.

Here, in the present invention, the sub-orifice is controlled to open and close in response to the pressure difference between the front and rear of the second orifice, and the sub-orifice is increased in opening area after the sub-orifice is closed. The structure is provided with a spool valve. For this reason, when the sub-orifice of the control orifice is closed and the flow rate of the working fluid returning to the drain passage increases, the opening area of the second orifice increases, so that the flow resistance by the second orifice is minimized. The working fluid that flows back to the drain passage through the second orifice flows smoothly without being subjected to the flow resistance by the second orifice. by this,
The internal pressure of the pump does not increase, and the operating efficiency of the pump does not decrease.

Therefore, an improved flow control device capable of flow-down control without lowering the pump efficiency due to an increase in the internal pressure of the pump can be obtained.

According to the third aspect of the present invention, the control orifice is formed on a shaft of the connector having a discharge passage, and the sub-spool valve is slidably fitted on the shaft of the connector. Since the second orifice is formed on the outer peripheral side of the sub-spool valve, the structure is simple and the improved flow control device can be easily obtained by changing the connector of the existing flow control device. it can.

According to the present invention, one end of the sub-spool valve is removably inserted into a damper chamber provided in the connector. Is moved, the vibration superimposed on the movement of the sub-spool valve is damped by the damper chamber, and the movement of the sub-spool valve becomes smooth.

According to the fifth aspect of the present invention, the second orifice is formed between the baffle member provided on the shaft of the connector and the outer periphery of the sub-spool valve. It can be easily formed.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
An embodiment applied to the flow control valve of the power steering device will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a flow control device showing an embodiment of the present invention. FIG. 2 is a front view of the baffle member shown in FIG. Sectional view (b)
, FIG. 3 is a drawing showing the flow rate characteristics, FIG. 4 is a cross-sectional view showing an enlarged part of FIG. 1, and FIG. 5 shows a state where the drain valve is opened by the spool valve shown in FIG. FIG.

The housing denoted by reference numeral 1 in the figure is formed integrally with the pump body 2. The housing 1 is provided with a spool valve receiving hole 5 whose one end is sealed by a sealing plug 3, and the open end of the spool valve receiving hole 5 is screwed and fixed under sealing by a seal ring 6. It is closed by the connector 7.

The connector 7 has a power steering device (not shown), that is, a discharge passage 8 communicating with an actuator.
And a hollow shaft (shaft) 9 protruding into the spool valve housing hole 5 is provided. A control orifice 10 is formed in the hollow shaft 9 to communicate the discharge passage 8 with the inside of the spool valve receiving hole 5.
In this embodiment, an axial main orifice 1 is provided.
1 and a radial sub-orifice 12 arranged in parallel with the main orifice 11. The connector 7 has a peripheral groove 13 and an oblique through hole 14 which is opened at the bottom of the peripheral groove 13 and communicates with the discharge passage 8.

A spool valve 15 is slidably inserted into the spool valve housing hole 5 whose opening end is closed by the connector 7. The first pressure chamber 16 and the second pressure chamber 17 are defined, and are always biased toward the first pressure chamber 16 with the spring force of the control spring 18 housed in the second pressure chamber 17. A drain passage 19 communicating with a reservoir (not shown) is closed by the body (land). The first pressure chamber 16 defined by the spool valve 15 has an introduction passage 20 for introducing a discharge fluid (working fluid) from a pump (not shown).

A blind hole-shaped passage 21 is formed in the housing 1 substantially in parallel with the spool valve housing hole 5. The passage 21 has an open end closed by a plug 22, one end communicating with the peripheral groove 13 of the connector 7 through the pressure-sensitive orifice 23 and the oblique hole 24, and the other end through the passage 25. It communicates with the pressure chamber 17. The passage 25
Is bored across the second pressure chamber 17 in the diameter direction,
Its open end is closed by a stopper 26.

The spool valve 15 has a drain passage 19
And a diametrical through hole 31 opening at the bottom of the circumferential groove 30, and a second through hole communicating with the through hole 31.
An axial blind hole 32 that opens toward the pressure chamber 17 is provided. In the blind hole 32, a ball valve 33 is biased together with its pusher 34 by a check spring 35 so that a valve seat 37 of a hollow tail plug 36 is provided.
A relief valve 38 adapted to the above is provided. Accordingly, the discharge passage 8 guided to the second pressure chamber 17 through the pressure-sensitive orifice 23 by the relief operation of the relief valve 38.
To avoid overpressure. A filter 39 is provided at the end of the hollow tail plug 36 on the second pressure chamber 17 side.
Is provided.

A second orifice 45 is provided upstream of the control orifice 10. A sub-spool for controlling the opening area of the control orifice 10 in response to the pressure difference between the front and rear of the second orifice 45 and increasing the opening area of the second orifice 41 when the opening area of the control orifice 10 is reduced. A valve 46 is provided.

In this embodiment, the second orifice 45 includes a sub-spool valve 46 provided on the outer periphery of the hollow shaft 9 of the connector 7 and a cylindrical baffle member 47 disposed on the outer periphery of the sub-spool valve 46. It is formed annularly between. The sub-spool valve 46 is formed in a substantially cylindrical shape with both ends open, and is slidably provided on the outer peripheral side of the hollow shaft 9 of the connector.

That is, the sub-spool valve 46 is formed in a substantially cylindrical shape with both ends open, and its outer peripheral side is formed with a small diameter portion 48 at a substantially central portion in the axial direction and a middle diameter portion 49 at one end.
A large diameter portion 50 is formed on the other end side, and the large diameter portion 50 is formed by a predetermined length from an axial end surface. The sub-spool valve 46 has a middle diameter portion 49 on one end side of the connector 7.
The large-diameter portion 50 on the distal end side is disposed on the distal end side of the hollow shaft 9. The opening area of the control orifice 10 can be controlled by moving the outer periphery of the hollow shaft 9 in the axial direction and controlling the opening and closing of the sub orifice 12.

The baffle member 47 is formed in a substantially cylindrical shape from a thin steel plate material and, as shown in FIG. 2, a plurality of baffle members 47 extending inward in the radial direction from the outer peripheral position on one end side of the cylindrical shape (four in this embodiment). ) Is provided.
Is mounted on the outer end of the sub-spool valve 46 by attaching the inner end to the tip of the hollow shaft 9 of the connector 7.
The baffle member 47 has a reduced-diameter portion 55 formed therein, and the open end of the baffle member 47 extends from the reduced-diameter portion 55 toward the opening end toward the introduction passage 20 of the second orifice 45. The tapered shape is formed so as to increase the opening area, and the reduced-diameter portion 55 is provided with a large-diameter portion of the sub-spool valve 46 in a state where the middle-diameter portion 49 of the sub-spool valve 46 has entered the damper chamber 51 most. It is formed at a position corresponding to 50.

A spring member 56 is provided between the sub-spool valve 46 and the rib 54 of the baffle member 47. The spring force of the spring member 56 causes the sub-spool valve 46 to always move toward the damper chamber 51. Being energized.

Thus, the second orifice 45
Is formed between the sub-spool valve 46 and the baffle member 47. The sub-spool valve 46 can change the opening area of the second orifice 45 by moving in the axial direction. That is, depending on whether the large-diameter portion 50 of the sub-spool valve 46 is located at a position corresponding to the reduced-diameter portion 55 of the baffle member 47 or the same, the small-diameter portion 48 is located at a position corresponding to the reduced-diameter portion 55. The opening area of the two orifices 45 will change. When the small-diameter portion 48 of the sub-spool valve 46 is located at a position corresponding to the reduced-diameter portion 55 of the baffle member 47, the opening area of the second orifice 45 is increased. In this state, the opening area of the control orifice 10 is reduced by closing the sub-orifice 12 by moving in the axial direction.

The sub-spool valve 46 is provided with a second orifice 45 on the outer peripheral side of the sub-spool valve 46, and is movable in the axial direction in response to a pressure difference between the front and rear of the second orifice 45. .

Therefore, the sub-spool valve 46 is
The opening area of the control orifice 10 is controlled in response to the pressure difference between the front and rear of the second orifice 45, and the control orifice 10
When the opening area of the second orifice 45 is reduced, the opening area of the second orifice 45 can be increased.

In such a configuration, the first pressure chamber 1
A working fluid discharged from a pump (not shown) is guided into the inside 6 through an introduction passage 20. The working fluid guided into the first pressure chamber 16 is guided to a control orifice 10 formed in the hollow shaft 9 of the connector 7 through a second orifice 45, and a restricted flow passing through the control orifice 10, Spool valve 1 based on differential pressure across control orifice 10
This occurs only when the drain passage is opened due to the movement of the fluid 5, but is diverted from the second orifice 45 to the excess oil flow that escapes through the drain passage 19 to the pump suction chamber and the reservoir (neither is shown). .

The working fluid passing through the control orifice 10 passes through the two orifices 11 and 12 because the control orifice 10 is composed of the main orifice 11 and the sub orifice 12 arranged in parallel with the main orifice 11. Will pass.

Thus, under the restriction of the control orifice 10, the required amount of working fluid is guided from the discharge passage to the actuator (not shown) of the power steering device, and the required steering assisting force is obtained.

At this time, when the flow rate of the hydraulic oil guided into the first pressure chamber 16 is small, the spool valve 15 is urged toward the first pressure chamber 16 by the spring force of the control spring 18 attached thereto. And the drain passage 19 is closed, the flow rate of the working fluid passing through the second orifice 45 is small, and the differential pressure across the second orifice 45 is small.
The sub-orifice 12 is not closed, and the spool valve 15 moves and controls the flow rate by balancing the differential pressure across the control orifice 10 and the spring force of the control spring 18. When the flow rate of the working fluid introduced into the first pressure chamber 16 increases, the differential pressure across the control orifice 10 increases, so that the spool valve 15
8, the sub-spool valve 46 closes the sub-orifice 12 of the control orifice 10 by increasing the differential pressure across the second orifice 45. Moves by the balance between the pressure difference between the front and rear of the control orifice 10 and the spring force of the control spring 18 to control the flow rate.

More specifically, when the flow rate of the hydraulic oil introduced into the first pressure chamber 16 is small, the spool valve 15 is urged toward the first pressure chamber 16 by the spring force of a control spring 18 attached thereto. And the drain passage 19 is closed. Further, since the flow rate of the working fluid passing through the second orifice 45 is small and the differential pressure across the second orifice 45 is small, the sub-spool valve 46 is urged toward the damper chamber 51 by the spring force of the spring member 56. Therefore, the sub-orifice 12 of the control orifice 10 is not closed, and the opening area of the second orifice 45 is not increased. That is, the large diameter portion 5 of the sub-spool valve 46
0 is located at a position corresponding to the reduced diameter portion 55 of the baffle member 47, and the opening area of the second orifice 45 is
6 is formed by the large diameter portion 50 and the reduced diameter portion 55 of the baffle member 47. Therefore, the spool valve 15 moves by the balance between the pressure difference between the front and rear of the control orifice 10 and the spring force of the control spring 18, and the flow rate passing through the control orifice 10 is controlled to the flow rate indicated by AB in FIG. .

When the flow rate of the working fluid introduced into the first pressure chamber 16 increases, the differential pressure across the control orifice 10 increases, causing the spool valve 15 to move against the spring force of the control spring 18. The drain passage 19 is opened. In this state, if the differential pressure across the second orifice 45 is equal to or less than a predetermined value, the sub-spool valve 46 is in a position biased toward the damper chamber 51 by the spring force of the spring member 56, and the control orifice 10 The sub-orifice 12 is not closed, and the opening area of the second orifice 45 is not increased. As a result, the spool valve 15 moves due to the balance between the differential pressure across the control orifice 10 and the spring force of the control spring 18, and the flow rate passing through the control orifice 10 is a constant flow rate (Q1) indicated by BC in FIG. Is controlled.

Next, as the flow rate of the working fluid passing through the second orifice 45 increases, a pressure difference occurs before and after the second orifice 45, and the second orifice 45
The upstream side has a higher pressure than the downstream side. As a result, the sub-spool valve 46 moves toward the distal end of the hollow shaft 9 against the spring force of the spring member 56, and gradually closes the sub-orifice 12. Thus, the working flow rate through the control orifice 10 is substantially reduced. When the sub-orifice 12 is closed, the working fluid passes only through the main orifice 11. As a result, the spool valve 15 opens and closes the differential pressure between the control orifice 10 and the control spring 1 whose opening area is substantially reduced.
8 and the flow rate passing through the control orifice 10 is equal to the flow rate (Q
From 1), the flow rate is controlled to the limited flow indicated by CD. When the sub-spool valve 46 closes the sub-orifice 12, the small-diameter portion 48 of the sub-spool valve 46 reaches a position corresponding to the reduced-diameter portion 55 of the baffle member 47. Is reduced, the opening area of the second orifice 45 is increased.

After the sub-spool valve 46 closes the sub-orifice 12 of the control orifice 10 (see FIG. 5).
The spool valve 15 moves by the balance between the pressure difference between the front and rear of the control orifice 10, which is only the main orifice 11, and the spring force of the control spring 18.
Is controlled to a constant flow rate (Q2) after D in FIG. Thus, the working fluid guided from the discharge passage 8 to the actuator (not shown) is flow-down controlled. Further, the second orifice 45 continues to have a state in which the small-diameter portion 48 of the sub-spool valve 46 is located at a position corresponding to the reduced-diameter portion 55 of the baffle member 47, so that the opening area thereof is increased. Is done.

Here, according to the present invention, the opening area of the control orifice 10 is controlled in response to the pressure difference between the front and rear of the second orifice 45, and when the opening area of the control orifice 10 is reduced, The configuration is such that a sub-spool valve 46 for increasing the opening area of the two orifices 45 is provided.
That is, in this embodiment, the control orifice 10 comprises a main orifice 11 and a sub-orifice 12, and controls the opening and closing of the sub-orifice 12 in response to the differential pressure across the second orifice 45. A sub-spool valve 46 is provided to increase the opening area of the second orifice 45 after closing the valve 12. For this reason, when the opening area of the control orifice 10 is reduced and the flow rate of the working fluid flowing back to the drain passage 19 increases, that is, when the sub-orifice 12 of the control orifice 10
Is closed to increase the flow rate of the working fluid flowing back to the drain passage 19, the opening area of the second orifice 45 increases, so that the flow resistance by the second orifice 45 is reduced as much as possible. Thereby, the second
The working fluid that flows back to the drain passage 19 through the orifice 45 smoothly flows without receiving the flow resistance of the second orifice 45. As a result, the internal pressure of the pump does not increase, and the operation efficiency of the pump does not decrease.

Therefore, an improved flow control device capable of performing flow-down control without increasing the internal pressure of the pump and lowering the pump efficiency can be obtained.

The control orifice 10 is formed on the hollow shaft 9 of the connector 7 having the discharge passage 8, and the sub-spool valve 46 is slidably fitted on the hollow shaft 9 of the connector 7. Orifice 45 is sub-spool valve 46
Since it is formed on the outer peripheral side, the structure is simple, and an improved flow control device can be easily obtained by changing the connector of the existing flow control device.

Further, since one end (medium diameter portion 49) of the sub-spool valve 46 is inserted into the damper chamber 51 provided in the connector 7 so as to be able to protrude and retract, the sub-spool valve 46 is actuated by the differential pressure across the second orifice 45. When the sub-spool valve 46 moves, the vibration superimposed on the sub-spool valve 46 moves.
1 and the movement of the sub-spool valve 46 becomes smooth.

Further, since the second orifice 45 is formed between the baffle member 47 provided on the hollow shaft 9 of the connector 7 and the outer periphery of the sub-spool valve 46, the second orifice 45 can be easily formed. Can be.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment, and can be changed without departing from the spirit of the invention.

[0061]

As described in detail above, according to the present invention, an improved flow control valve capable of flow-down control without increasing the internal pressure of the pump and lowering the pump efficiency can be obtained. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flow control device according to an embodiment of the present invention.

FIG. 2 is a drawing showing the baffle member shown in FIG. 1 in a front view (a) and a sectional view (b) along the line AOA of the front view (a).

FIG. 3 is a drawing showing flow characteristics.

FIG. 4 is an enlarged view showing a main part of FIG. 1;

FIG. 5 is a view similar to FIG. 4, but showing a state in which the drain valve is opened by the spool valve shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 5 spool valve accommodation hole 8 discharge passage 10 control orifice 11 main orifice 12 sub orifice 15 spool valve 16 first pressure chamber 17 second pressure chamber 18 control spring 19 drain passage 20 introduction passage 45 second orifice 46 sub spool valve

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kaori Mino 1370 Onna, Atsugi-shi, Kanagawa Prefecture F-term in Unisia Gex Corporation (reference) 3D033 FE06 FE09 FE11 FE12 3H060 AA09 BB06 DC05 DC10 DC14 EE04 GG08 HH04 HH19 3H067 AA17 CC04 CC16 DD05 DD33 5H307 AA11 BB07 CC05 DD02 EE02 EE09 EE17 ES02 GG04 JJ03 KK01 KK05

Claims (5)

[Claims] A spool valve is slidably housed in a spool valve housing hole, and a first pressure chamber and a second pressure chamber are defined in the spool valve housing hole, and a control orifice is provided in the first pressure chamber. And a control spring for guiding the pressure of the discharge passage and biasing the spool valve toward the first pressure chamber in the second pressure chamber. A flow control device that guides a required flow rate of a working fluid from an introduction passage to a discharge passage via a control orifice, while returning excess fluid to the required flow rate to a drain passage that is controlled to be opened and closed by movement of a spool valve. A second orifice is provided on the upstream side, and the opening area of the control orifice is controlled in response to a pressure difference between the front and rear of the second orifice; A flow control device, comprising: a sub-spool valve for increasing the opening area of the second orifice when the product is reduced. 2. A spool valve is slidably received in a spool valve receiving hole, a first pressure chamber and a second pressure chamber are defined in the spool valve receiving hole, and a control orifice is provided in the first pressure chamber. And a control spring for guiding the pressure of the discharge passage and biasing the spool valve toward the first pressure chamber in the second pressure chamber. A flow control device that guides a required flow rate of a working fluid from an introduction passage to a discharge passage via a control orifice, while returning excess fluid to the required flow rate to a drain passage that is controlled to be opened and closed by movement of a spool valve. While the second orifice is provided on the upstream side, the control orifice is composed of a main orifice and a sub-orifice arranged in parallel with the main orifice. A sub-spool valve that controls opening and closing of the sub-orifice in response to the differential pressure across the second orifice, and increases the opening area of the second orifice after the sub-orifice is closed.
Flow control device. 3. The control orifice is formed in a shaft portion of a connector having a discharge passage, a sub-spool valve is slidably fitted on the shaft portion of the connector, and a second orifice is formed on an outer periphery of the sub-spool valve. The flow control device according to claim 1, wherein the flow control device is formed on a side. 4. The flow control device according to claim 3, wherein one end of the sub-spool valve is removably inserted into a damper chamber provided in the connector. 5. The flow control device according to claim 3, wherein the second orifice is formed between a baffle member provided on a shaft portion of the connector and an outer periphery of a sub spool valve.