JP2001097233A - Flow control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow control device capable of controlling assist force according to the car speed and always keeping the assist force constant regardless of load variation. SOLUTION: This flow control device includes a spool hole 4 communicating with a pump port 2 and a tank port 3, a spool 5 slidably incorporated in the spool hole 4 to partition the spool hole 4 into a control chamber 10 and a pilot chamber 12, an actuator port 42 communicating with the control chamber 10, a spring 13 provided in the pilot chamber 12 to apply spring force to the spool 5, a pilot passage 14 communicating the actuator port 42 with the pilot chamber 12, a variable throttle V provided between the control chamber 10 and the actuator port 42, and a regulating mechanism S for regulating the opening of the variable throttle V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device capable of controlling an assist force of a power steering device according to a vehicle speed.

[0002]

2. Description of the Related Art A conventional example shown in FIG.
In addition, a pump port 2, a tank port 3, and a spool hole 4 communicating with both ports 2, 3 are formed.
The pump P is connected to the pump port 2, and the tank T is connected to the tank port 3. A spool 5 is slidably incorporated in the spool hole 4. A connector 8 is fixed to the opening on the right side of the spool hole 4 in the drawing, and a power steering device PS is connected to an actuator port 7 formed in the connector 8. In addition, this power steering device PS includes:
It has an open center type valve and a cylinder that applies assisting force to the steered wheels.

An orifice member 9 is fixed to the connector 8, and a control chamber 10 is provided between the orifice member 9 and the spool 5. And this control room 10
And the orifice member 9
The orifice 11 is formed through the orifice 11. Spool hole 4 on the opposite side of control room 10 and spool 5
Inside, a spring 13 is provided. The spring force of the spring 13 is applied from the left side of the spool 5 in the drawing to push the stopper 6 of the spool 5 against the orifice member 9. However, a groove (not shown) is formed on the left side surface of the orifice member 9 against which the stopper 6 is pressed, and the control chamber 10 and the actuator port 7 are communicated through this groove.

A chamber provided with a spring 13 in the spool hole 4 is referred to as a pilot chamber 12.
A pilot passage 14 formed in the valve body 1,
It communicates with the actuator port 7 through a throttle passage 15 formed between the connector 8 and the orifice member 9. Thus, the load pressure of the actuator port 7 is led to the pilot chamber 12.

Further, a discharge port 24 communicating with the pilot chamber 12 is formed in the valve body 1, and a tank T is connected to the discharge port 24 via a discharge passage 22. In the discharge passage 22, a proportional solenoid valve 23 is provided, and a controller (not shown) is connected to the solenoid 23a. Then, the exciting current of the solenoid 23a is
The control is performed according to the vehicle speed. For example, if the solenoid 23a is kept de-energized, the proportional solenoid valve 23 is kept closed, and the communication between the pilot chamber 12 and the tank T is cut off. When the solenoid 23a is excited, the proportional solenoid valve 23 keeps the opening proportional to the exciting current, connects the pilot chamber 12 with the tank T, and discharges the pressure oil in the pilot chamber 12 to the tank T.

The spool 5 has a relief hole 1
6, one of which is opened to the pilot chamber 12,
The other end is opened in an annular groove 17 formed in the spool 5. The seat member 18, the ball 19, the spring receiver 20, and the spring 21 are incorporated in the relief hole 16, and the relief valve R is configured by these members.

In the conventional example described above, when the pressure oil of the pump P is supplied to the control chamber 10 through the pump port 2 from the state shown in FIG.
Moves to the left in the drawing, and the control chamber 10 and the actuator port 7 are largely communicated via the orifice 11.
Therefore, the pressure oil guided to the control room 10 is supplied to the orifice 1
The actuator 1 is guided to the actuator port 7 through the actuator port 1 and supplied to the power steering device PS from the actuator port 7.

At this time, when the pressure oil passes through the orifice 11, a pressure difference occurs before and after the orifice 11. Then, the pressure on the upstream side of the orifice 11 acts on the pressure receiving surface of the spool 5 in the control chamber 10. If the proportional solenoid valve 23 is closed, the pressure on the downstream side of the orifice 11 is changed from the actuator port 7 to the throttle passage 15.
→ Pilot passage 14 → Guided to pilot room 12,
It acts directly on the pressure receiving surface of the spool 5 in the pilot chamber 12.

Therefore, the balance position of the spool 5 is maintained such that the pressure in the control chamber 10 is higher than the pressure in the actuator port 7 by an amount corresponding to the spring force of the spring 12. Then, when the spool 5 moves to the left in the drawing to communicate the tank port 3 with the control chamber 10, an excess flow rate corresponding to the communication opening degree is returned to the tank T, and the required flow rate is set via the orifice 11. Actuator port 7 → supplied to power steering device PS.
Therefore, the power steering device PS exerts an assisting force according to the required flow rate.

Further, when the load pressure on the actuator port 7 side increases, such as when the steering is turned off, the pressure in the pilot chamber 12 also increases accordingly. Therefore, the spool 5 moves rightward in the drawing, the communication opening degree of the tank port 3 decreases, and the pressure in the control chamber 10 increases. That is, the spool 5 maintains the balance position so that the pressure in the control chamber 10 is higher than the pressure in the actuator port 7 by the amount corresponding to the spring force of the spring 12. When the proportional solenoid valve 23 is closed as described above, a constant flow is always supplied to the power steering device regardless of the load fluctuation of the power steering device PS, and the assist force is kept constant.

On the other hand, when the opening of the proportional solenoid valve 23 is increased by controlling the exciting current of the solenoid 23a by the controller from the above state, the pilot chamber 1
The second pressure oil is discharged to the tank T via the discharge port 24 → the discharge passage 22 → the proportional solenoid valve 23. When the pressure oil in the pilot chamber 12 is discharged, the pressure oil in the actuator port 7 is discharged to the tank T via the throttle passage 15 → the pilot passage 14 → the pilot chamber 12 → the discharge port 24 → the discharge port 22.

When a flow occurs in the throttle passage 15 as described above, a pressure difference occurs in the throttle passage 15. The pressure difference before and after the throttle passage 15 is different between the control chamber 10 and the pilot chamber 1.
2, the spool 5 moves to the left in the drawing as the pressure difference increases. Then, when the spool 5 moves to the left in the drawing, the communication opening between the tank port 3 and the control chamber 10 increases.
The flow rate supplied to the power steering device PS via the actuator port 7 decreases as the flow rate escaping from the tank port 3 increases. Therefore, when the opening of the proportional solenoid 23 is increased, the assisting force of the power steering device PS decreases, and the assisting force is suitable for high-speed traveling.

Conversely, when the opening of the proportional solenoid valve 23 is reduced, the flow rate passing therethrough decreases, so that the pressure difference across the throttle passage 15 also decreases.
Therefore, the spool 5 returns to the right in the drawing, and the communication opening between the tank port 3 and the control chamber 10 decreases. Therefore, the flow rate discharged through the tank port 3 decreases,
Accordingly, the flow rate supplied to the power steering device PS via the actuator port 7 increases. When the supply amount of the power steering device PS increases as described above, the assist force of the power steering device PS increases, and the assist force is suitable for low-speed traveling. As described above, in this conventional example, by controlling the opening of the proportional solenoid valve 23, an assisting force corresponding to the vehicle speed can be obtained.

[0014]

However, in this conventional example, when the assist force is controlled according to the vehicle speed,
When the load of the power steering device PS changes, the assist force sometimes changes. For example,
When the opening of the proportional solenoid valve 23 is increased to reduce the assisting force of the power steering device PS, when the load on the power steering device PS increases, the pressure in the pilot chamber 12 increases accordingly. When the pressure in the pilot chamber 12 increases, the flow rate discharged through the proportional solenoid valve 23 increases, so that the flow rate passing through the throttle passage 15 also increases. As the flow rate passing through the throttle passage 15 increases, the pressure difference before and after the throttle passage 15 also increases, and accordingly, the pressure difference between the control chamber 10 and the pilot chamber 12 increases.

When the pressure difference increases in this way, the spool 5 moves to the left in the drawing, so that the communication opening degree of the tank port 3 increases, and accordingly the power is supplied to the power steering device PS via the actuator port 7. The flow decreases. Therefore, there is a problem that the assisting force of the power steering device PS decreases. It is an object of the present invention to provide a flow control device capable of controlling an assist force according to a vehicle speed and maintaining the controlled assist force constant regardless of a load change. .

[0016]

According to a first aspect of the present invention, there is provided a housing in which a pump port and a tank port are formed, a spool hole formed in the housing and communicating with the pump port and the tank port, and a sliding hole formed in the spool hole. A spool that movably incorporates the spool hole into a control chamber and a pilot chamber, an actuator port that communicates with the control chamber, and a spring that is provided in the pilot chamber and that applies a spring force to the spool. A pilot passage communicating the actuator port with the pilot chamber, a variable throttle provided between the control chamber and the actuator port, and an adjustment mechanism for adjusting the opening of the variable throttle. And

According to a second aspect of the present invention, the variable throttle according to the first aspect of the present invention comprises a communication path for communicating the control chamber with the actuator port and a poppet member which can be inserted into the communication path, while the adjusting mechanism is provided. Consists of a spring that applies a spring force to a poppet member, and a proportional solenoid that moves the poppet member in the axial direction against the spring force. When the proportional solenoid is de-energized, the poppet member The communication passage is narrowed by force.

[0018]

1 and 2 show an embodiment of the present invention. The structure of a spool 5 incorporated in a spool hole 4 and a relief valve R incorporated in the spool 5 is the same as that of the conventional example. Since they are the same, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

A connection portion 25 for a proportional solenoid S is attached to the opening on the right side of the spool hole 4 in the drawing. A guide hole 26 is formed in the connection portion 25, and an orifice member 27 is provided at an opening on the left side of the guide hole 26 in the drawing. The guide hole 26 and the control chamber 10 communicate with each other through a communication passage 29 formed in the orifice member 27.
A poppet member 31 is provided in the guide hole 26, and a poppet portion 32 of the poppet member 31 is provided.
Can be freely inserted into the communication passage 29. The gap between the annular convex portion 35 formed in the communication passage 29 and the poppet portion 32 forms a variable stop V.

As shown in FIG. 2, the poppet member 31 has a pair of sliding portions 30, each having a fan-shaped cross section.
By providing the sliding portions 30 and 30 in sliding contact with the guide holes 26, the axis of the poppet member 31 and the axis of the communication passage 29 are aligned. If the axes of the poppet member 31 and the axis of the communication passage 29 are made to coincide with each other in the sliding portions 30, the poppet member 32 and the annular convex portion 35 can be formed simply by incorporating the poppet member 31 into the spool hole 4. The precision of the variable aperture V constituted by the above can be kept high.

The orifice member 27 and the sliding parts 30, 3
Between them, a spring 36 is provided. And
The sliding portions 30 and 30 function as a spring receiver for the spring 36, and the spring force of the spring 36 acts on the poppet member 31. The poppet member 31 to which the spring force of the spring 36 acts as described above moves to the right in the drawing, and presses the right end of the poppet against the push rod 37 of the proportional solenoid S. In this pressed state,
The inclined portion 34 formed in the poppet portion 32 is brought close to the annular convex portion 35 to form a small gap between the inclined portion 34 and the annular convex portion 35. That is, the variable aperture V
However, the communication between the control room 10 and the guide hole 26 is most narrowed.

The stopper 6 of the spool 5 is pressed on the left side of the orifice member 27 in the drawing by the spring force of the spring 12. However, a groove 28 is formed on the left side surface of the orifice member 27 in the drawing, and the groove 28 is connected to the communication passage 29. Therefore, even when the stopper 6 is pressed against the orifice member 27, the control chamber 10 and the guide hole 26 communicate with each other.

At the right end of the poppet member 31 in the drawing,
The push rod 37 of the proportional solenoid S is abutted, and the exciting current of the proportional solenoid S is controlled by a controller (not shown). When the proportional solenoid S is excited to apply a thrust to the push rod 37, the poppet member 31 moves to a position where the thrust by the push rod 37 and the spring force of the spring 13 are balanced. The opening of the variable throttle V is determined according to the position. That is, the larger the exciting current of the proportional solenoid S, the larger the opening of the variable throttle V. A vehicle speed sensor is connected to the controller, and the controller controls the exciting current based on a vehicle speed signal from the vehicle speed sensor.

On the other hand, a pilot hole 38 is formed in the connection portion 25, and this pilot hole 38 is
In the annular concave portion 39 formed at the end. The annular recess 39 communicates with the pilot passage 14. In addition, a supply passage 40 is formed in the connection portion 25, and the supply passage 40 is provided on the outer periphery of the connection portion 25.
The first actuator port 42 is in communication with the first actuator port 42. The actuator port 42 is connected to a power steering device PS.

In the embodiment described above, for example, while the vehicle is running, if the controller determines that the speed is high based on a signal from the vehicle speed sensor, the opening of the variable throttle V is reduced. If the opening degree of the variable throttle V becomes small, a large pressure difference occurs before and after the variable throttle V. The pressure on the upstream side of the variable throttle V acts on the spool pressure receiving surface of the control chamber 10, and the pressure on the downstream side of the variable throttle V acts on the spool pressure receiving surface of the pilot chamber 12.
Is given a large thrust in the left direction in the drawing.

Therefore, the spool 5 moves in the left direction in the drawing while resisting the spring force of the spring 13 by this thrust.
That is, it moves in a direction to open the tank port 3. The more the tank port 3 is opened, the more the power steering device P
Since the flow rate supplied to S decreases, the assist force of the power steering device PS decreases. That is, the variable aperture V
By reducing the opening of the vehicle, a small assist force suitable for high-speed traveling can be obtained.

When the controller determines that the speed is low based on a signal from the vehicle speed sensor, the controller increases the opening of the variable aperture V. If the opening degree of the variable throttle V increases, the pressure difference generated before and after the opening degree decreases, and the spool 5 moves to the right in the drawing, that is, the direction to close the tank port 3 by the spring force of the spring 13. The closer the tank port 3 is closed, the greater the flow rate supplied to the power steering device PS, and thus the greater the assisting force. That is, by increasing the opening degree of the variable throttle V, a large assist force suitable for low-speed traveling is obtained.

As described above, in this embodiment, the assisting force of the power steering device PS can be adjusted according to the vehicle speed by controlling the opening of the variable throttle V according to the vehicle speed.

Further, in this embodiment, the load pressure on the actuator port 42 side and the pressure in the pilot chamber 12 are kept at the same pressure. Same as when closed. Therefore, according to this embodiment, the assist force can always be kept constant irrespective of the load fluctuation of the power steering device PS, as in the case where the proportional solenoid valve 23 is closed in the conventional example. That is, according to this embodiment, the assisting force of the power steering device PS can be controlled according to the vehicle speed, and the controlled assisting force can always be kept constant regardless of the load fluctuation.

On the other hand, when the current is not supplied to the proportional solenoid S due to a failure or the like, the inclined portion 34 of the poppet member 31 causes the annular convex portion 35
In a state close to. Therefore, the variable throttle V is in the state where it is most narrowed, and the pressure oil supplied to the power steering device PS is reduced. Therefore, the state becomes close to what is called manual steering, and a reliable fail-safe effect can be obtained.

Further, even when the valve of the power steering device PS is neutral and does not require an assisting force, the opening of the variable throttle V is made extremely small as described above. If the opening degree of the variable throttle V is made extremely small in this way, most of the pressure oil is discharged from the tank port 3 and a small flow rate is discharged from the power steering device PS. Therefore, the effects described below can be obtained.

That is, since the valve of the power steering device PS is an open center type, when it is in a neutral position, the supplied pressure oil is returned to the tank T as it is. However, at this time, the power steering device P
Energy loss occurs due to the S pipe resistance and the like. Therefore, in this embodiment, when the assisting force of the power steering device PS is not required, most of the pressure oil is discharged directly from the tank port 3, and the pressure oil is discharged from the power steering device PS side. Energy loss is reduced. Since a small amount of pressure oil is also supplied to the power steering device PS, the responsiveness when the power steering device PS operates does not deteriorate.

In this embodiment, the valve body 1,
Although the connection part 25 and the port member 41 constitute the housing of the present invention, they may be constituted by one member.
In this embodiment, the communication passage 29 and the poppet member 31
The variable throttle is constituted by the gap, but the configuration is not limited as long as the opening degree of the flow path can be adjusted. Further, in this embodiment, the poppet member 31 is moved in the axial direction by the proportional solenoid S. However, an actuator may be used as long as the position of the poppet member 31 in the axial direction can be adjusted.

[0034]

According to the first aspect of the invention, the flow rate supplied to the actuator port can be adjusted by controlling the opening of the variable throttle. Moreover, the flow rate supplied to the actuator port can be kept constant regardless of the load on the actuator. Therefore, if the power steering device is connected to the actuator port and the opening of the variable throttle is controlled according to the vehicle speed, the power steering device P
The assisting force of S can be controlled according to the vehicle speed, and the controlled assisting force can be kept constant regardless of the load variation.

According to the second aspect of the present invention, the communication path is narrowed when the proportional solenoid is in the non-excited state. Therefore, when current is not supplied to the proportional solenoid due to a failure or the like, the pressure from the pump is reduced. The oil is supplied to the actuator port in a state where the oil is squeezed. Therefore, when the power steering device is connected to the actuator port, the power steering device PS can be controlled in a state close to the manual steering even if the current is not supplied to the proportional solenoid due to a failure or the like, and a reliable fail-sale effect can be obtained. Can be

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a cross-sectional view of the poppet member 31.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

S Proportional solenoid V Variable throttle 1 Valve body 2 that constitutes the housing of the present invention 2 Pump port 3 Tank port 4 Spool hole 5 Spool 10 Control room 12 Pilot chamber 13 Spring 14 Pilot passage 25 Connection of proportional solenoid that constitutes the housing of the present invention Portion 29 Communication Path 31 Poppet Member 36 Spring 41 Port Member Constituting Housing of the Present Invention 42 Actuator Port

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Shiozaki 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd. F-term (reference) 3D032 CC02 CC34 CC48 CC49 DA23 DB02 DB03 EB11 EC04 EC06 GG01 3D033 EB08 EB09 3H060 AA04 AA09 BB03 BB05 CC02 DC05 DD05 DD12 DD16 DD17 EE04 HH04 HH16 HH19

Claims (2)

[Claims] A housing formed with a pump port and a tank port, a spool hole formed in the housing and communicating with the pump port and the tank port, and slidably incorporated in the spool hole;
A spool that partitions the spool hole into a control chamber and a pilot chamber, an actuator port that communicates with the control chamber, a spring that is provided in the pilot chamber, and that applies a spring force to the spool; A flow control device, comprising: a pilot passage communicating with a pilot chamber; a variable throttle provided between the control chamber and the actuator port; and an adjusting mechanism for adjusting an opening of the variable throttle. 2. The variable throttle comprises a communication passage communicating the control chamber with the actuator port, and a poppet member which can be freely inserted into the communication passage, while the adjusting mechanism applies a spring force to the poppet member. And a proportional solenoid that moves the poppet member in the axial direction against the spring force. When the proportional solenoid is de-energized, the poppet member narrows the communication path by the spring force of the spring. The flow control device according to claim 1, wherein: