JP2001153245A - Flow control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow control device large in changing a return flow amount to a tank port relating to a change of an excitation current of a proportional solenoid controlling a supply flow amount to a power steering device from a pump. SOLUTION: In this invention, a diametrically spread annular groove 5A is provided in a connection part to a tank port 5 of a spool hole 1B, while a cylindrical notch 7A or a notch 7B partially diagonally notching a large diametric part end face is provided in the large diametric part end face in a side of a pump port 3 of a spool 7 guided by the spool hole, communication area with the tank port is increased relating to a stroke in the case the spool is moved to a tank port side.

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 which controls the opening of a variable throttle by the thrust of a solenoid and secures a flow according to the opening.

[0002]

2. Description of the Related Art As a flow control device for controlling the opening of a variable throttle by the thrust of a solenoid, for example, the one shown in FIG. 2 is known. Hereinafter, the related art will be described with reference to the drawings.

The main component of the housing H is a valve body 1 and a cap member 2 fitted at one end thereof.
The housing H has a pump port 3 connected to the pump P, an actuator port 4 connected to the power steering device PS, and a tank port 5 connected to the tank T. And the valve body 1
Has a spool hole 1B, a spool 7 is slidably incorporated in the spool hole 1B, and both sides thereof are partitioned into a control room 8 and a pilot room 9. In addition, a spring 10 is provided in the pilot chamber 9.

The spool 7 stops at a position where the pressure action of the control chamber 8, the pressure action of the pilot chamber 9, and the spring force of the spring 10 are balanced. The opening of the tank port 5 is determined according to the balance position. When the opening degree of the tank port 5 is determined, the flow rate of the supply flow from the pump P discharged to the tank T side and the power steering apparatus P
The split ratio with the flow rate supplied to the S side is determined. In other words, by controlling the split ratio, the flow rate supplied to the power steering device PS is controlled.

The above-mentioned split ratio is determined by the pump port 3
And the opening degree of the variable throttle V provided in the flow process between the actuator port 4. The variable diaphragm V has a diaphragm opening member 11 and a diaphragm poppet member 12 incorporated in the communication chamber 2A of the cap member 2 as main components.

The aperture opening member 11 is provided with a cap member 2.
And an aperture 11A is formed in the opening. The aperture poppet member 12 is
The poppet portion 12B provided at the tip thereof is
A is made to protrude more toward the control room 8 than A. The variable aperture V is constituted by the aperture section 11A and the poppet section 12B.

[0007] The pressure on the upstream side of the variable throttle V configured as described above acts on the pressure receiving surface of the spool 7 in the control chamber 8. The pressure on the downstream side of the variable throttle is guided to a pilot chamber 9 via a pilot passage 1A formed in the valve body 1, and acts on a pressure receiving surface of a spool 7 in the pilot chamber 9. Accordingly, when the pressure oil flows through the variable throttle V and a pressure difference occurs before and after that, as described above, the spool 7 causes the pressure action on the upstream side of the variable throttle V, the pressure action on the downstream side of the variable throttle V, It stops at a position where the spring force of the spring 10 is balanced.

The position at which the spool 7 stops is located on the left side of the drawing as the pressure difference before and after the variable throttle V increases. Because, when the pressure difference before and after the variable throttle V increases, the pressure on the control chamber 8 side increases
Therefore, the force of pushing the spool 7 leftward in the drawing by the pressure action of the control chamber 8 is relatively larger than the force pushing the spool 7 rightward in the drawing by the pressure action of the pilot chamber 9. Because it becomes.

When the spool 7 moves to the left in the drawing as described above, the opening of the tank port 5 increases, and the tank T
The flow rate supplied to the power steering device PS decreases as the flow rate discharged to the power steering apparatus increases.

The pressure difference generated before and after the variable throttle V is inversely proportional to the opening of the variable throttle V. That is,
If the pressure in the control chamber 8 is constant, the pressure difference before and after the variable throttle V decreases as the opening of the variable throttle V increases, and the pressure difference increases as the opening decreases.
In this conventional example, the opening of the variable throttle V is adjusted by moving the poppet portion 12B in the axial direction.

Hereinafter, a mechanism for adjusting the opening of the variable throttle V will be described. In the throttle poppet member 12 provided with the poppet portion 12B, a passage 12C to the power steering device PS is provided in a central guide portion, and a sub-spring 17 is provided between the guide portion and the throttle opening member 11. . The force in the direction in which the opening degree of the variable throttle V decreases decreases is applied to the throttle poppet member 12 by the spring force Kx of the sub-spring 17.

On the other hand, a proportional solenoid S is provided on the right end side of the stop poppet member 12, and the push rod 18 pushes the right end surface 12A of the stop poppet member 12. By pushing the right end face 12A with the push rod 18 in this manner, the diaphragm poppet member 12 is pressed.
, A force Fx in the direction of increasing the opening of the variable throttle V is applied.

Therefore, the pressure on the upstream side of the variable throttle V is P ₁ , the pressure on the downstream side of the variable throttle V is P ₂ ,
Assuming that both the pressure receiving areas of _No. 6 are a ₁ and a ₁ and the pressure receiving area of the poppet portion 12B is a ₂ , the balance condition of the throttle poppet member 12 is as follows. a ₁ · P ₂ + Fx = a ₁ · P ₂ + a ₂ · P ₁ + Kx + F However, since the force a ₁ · P ₂ acting on the spring receiver 16 is canceled, the above equation becomes as follows. Fx = a ₂ · P ₁ + Kx + F Here, F in the above equation is a fluid force, and is a force acting on the restrictor poppet member 12 in a direction to close the variable restrictor V when the fluid passes through the variable restrictor V.

The aperture poppet member 12 stops at a position satisfying the balance condition of the above equation to determine the opening of the variable aperture V. As is clear from this equation, the opening of the variable aperture V is proportional to It is controlled by the thrust Fx of the solenoid S. That is, when the exciting current of the proportional solenoid S is set to zero and the thrust Fx is set to zero, the opening degree of the variable throttle V is kept at a minimum. Further, as the exciting current is increased and the thrust Fx is increased, the opening degree of the variable throttle V is increased.

Here, the exciting current of the proportional solenoid S is controlled by a controller that outputs an exciting current based on a steering torque signal, a vehicle speed signal, and the like (not shown). For example, in a so-called neutral state where the steering torque signal is zero and the assisting force of the power steering device PS is not required, the controller sets the exciting current to zero and keeps the opening of the variable throttle V to a minimum. If the opening degree of the variable throttle V is minimized, the pressure difference occurring before and after the variable throttle V increases,
The communication area of the tank port 5 increases. By controlling the exciting current of the proportional solenoid S in this way, it is possible to control the ratio of the flow rate of the supply flow from the pump P to the flow rate discharged to the tank T and the flow rate discharged to the actuator side.

If the communication area of the tank port 5 is large, most of the flow rate supplied from the pump P is
And only a small flow rate is supplied to the power steering device PS. As described above, when the flow rate supplied to the power steering device PS is reduced, the energy loss caused by the pipe resistance of the power steering device PS is reduced.

That is, in this conventional example, when the power steering device PS is in the neutral state, the opening degree of the variable throttle V is reduced, thereby setting a so-called energy saving state in which energy loss is reduced. It should be noted that even when the power steering device PS is neutral, a small amount of pressure oil is supplied to the power steering device PS to prevent a response delay at the start of operation.

On the other hand, when a large assist force is required, for example, when a large steering torque is generated during low-speed running, the controller increases the exciting current of the proportional solenoid S to increase the opening of the variable throttle V. I do. If the opening degree of the variable throttle V is increased, the pressure difference occurring before and after the variable throttle V is reduced, and the communication area of the tank port 5 is reduced. Therefore, most of the flow rate supplied from the pump P is supplied to the power steering device PS, so that the power steering device PS can exert a large assisting force.

Here, the stroke Sx of the spool 7 is proportional to the exciting current of the proportional solenoid S, and the communication area Ax of the tank port 5 is substantially proportional to the stroke Sx of the spool 7, so that if the differential pressure is constant, the communication area The return flow rate to the tank port proportional to Ax can be controlled by the exciting current of the proportional solenoid S.

The stroke Sx of the spool 7 driven by the proportional solenoid S and the tank port 5
Is a graph indicated by a dotted line D in FIG. That is, in the related art in which the tank port 5 is circular (φ9), the change in the communication area Ax of the tank port 5 with respect to the stroke Sx of the spool 7 is small. It is necessary to increase or decrease the exciting current of S.

[0021]

In the above conventional example, the change in the communication area Ax of the tank port 5 with respect to the stroke Sx of the spool 7 (the return flow to the tank port with respect to the exciting current of the proportional solenoid S) is small. In order to increase the change in the communication area Ax (return flow rate), there is a problem that the increase or decrease of the exciting current of the proportional solenoid S must be increased. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a flow control in which a change in a return flow to a tank port is large with respect to an increase or decrease in an exciting current of a proportional solenoid S. It is to provide a device.

[0022]

SUMMARY OF THE INVENTION The present invention provides a housing having a pump port and an actuator port formed therein, a spool hole formed in the housing, a spool slidably incorporated in the spool hole, and one of the spools. When the spool is moved by the pressure action between the control chamber and the control chamber that is always communicated with the pump port, the pilot chamber that is partitioned on the other end face side of the spool, and the control chamber and the pilot chamber, A tank port is provided which communicates with the control chamber and whose communication area with the control chamber is controlled in accordance with the amount of movement of the spool, and a variable throttle provided in a communication process for communicating the pump port with the actuator port. .

The stop poppet member, which is a component of the variable stop, has a poppet portion at one end thereof, and the poppet portion faces the control room, and the poppet portion is brought into contact with the poppet portion by the pressure action of the control room. A force in the direction of decreasing the aperture is applied, and a spring force in the direction of decreasing the aperture is also applied to the aperture poppet member. It is assumed that a flow control device is provided with a push rod for applying a directional force, that is, a force for increasing the throttle opening degree, to a throttle poppet member and a solenoid for applying a thrust to the push rod.

Means adopted by the present invention to solve the problem is to provide an annular groove having an enlarged diameter at a portion where the spool hole is connected to the tank port, and to increase the size of the spool guided to the spool hole on the pump port side. A notch is provided in the end face of the diameter portion to increase the communication area with the tank port with respect to the stroke when the spool moves to the tank port side. " The notch may be a cylindrical shape provided on the end face of the large-diameter portion of the spool on the pump port side or a shape in which the end face of the large-diameter portion of the spool on the pump port side is partially obliquely cut.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to effectively use the movable range of a proportional solenoid, it is desirable to use a flow control valve having a large responsiveness to a change in the spool stroke and good responsiveness. In order to improve responsiveness, it is effective to greatly increase or decrease the communication area of the tank port with respect to the stroke of the spool. As a means for increasing the communication area, it is conceivable to increase the diameter of the tank port, but it is difficult to adopt the tank port due to space restrictions.

The present invention does not increase the space,
The present invention relates to a method for increasing a communication area of a tank port with respect to a stroke of a spool. The specific method is as shown in FIG.
And a circular groove equally arranged on the right end face of the large-diameter portion of the spool 7 as in the first embodiment shown in FIG. The notch 7A is provided. This is because, for the same stroke of the spool 7, the total area of the notches 7A can be made larger than the conventional communication area where the tank port 5 is circular (φ9).

Next, the process in which the response becomes faster will be specifically described. First, the variable throttle V is controlled by the proportional solenoid S.
Is decreased, the valve differential pressure before and after the variable throttle V increases, and the spool 7 moves by Fx in the direction in which the communication area of the tank port 5 increases. If the supply flow rate to the power steering device PS is the same, the opening area of the tank port can be the same in the present invention and in the conventional structure, so that the stroke Sx is smaller in the present invention.

When the proportional solenoid S operates in the direction to open the variable throttle V upon sensing the driver's steering, the differential pressure across the variable throttle V decreases and the spool 7 moves in the direction to close the tank port 5. In this case, the larger the change in the opening area is, the faster the required flow rate can be supplied to the power steering device PS even with the same movement amount.

FIG. 3 shows the stroke Sx [m
the opening area Ax [mm ^2] for m], in which indicated by a solid line in comparison with the conventional structure shown by a dotted line represents that the freely set a large opening area by the diameter and number of the notch 7A. Solid line A is φ3 × 9, B is φ3 × 6, C
Exemplifies the case of φ3 × 3.

The example in which the cylindrical notch 7A is provided on the right end face of the large diameter portion of the spool 7 has been described above. However, the notch does not necessarily need to be cylindrical, and is a right half section in FIG. As in the second embodiment shown in FIG. 1B, a notch 7 in which a corner of the right end face of the large diameter portion of the spool 7 is partially cut off obliquely.
B may be used. The cutout surface of the notch 7B has an arc shape when viewed from above, so that characteristics similar to those of the circular notch 7A can be obtained.

[0031]

According to the present invention, when the spool is driven by the proportional solenoid, the change in the communication area of the tank port is large even if the amount of movement of the spool is small. Since the supply can be performed promptly, it is possible to improve the steering followability without causing the flow rate shortage to the power steering device side.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a flow control valve according to the related art.

FIG. 3 is a graph showing a relationship between a stroke Sx of a spool and a communication area Ax of a tank port.

[Explanation of symbols]

 H Housing S (Proportional) solenoid V Variable throttle 1B Spool hole 3 Pump port 4 Actuator port 5 Tank port 5A Annular groove 7 Spool 7A Cylindrical notch 7B Diagonally notched notch 8 Control room 9 Pilot chamber 12 Throttle poppet member 12B Poppet part 17 Sub-spring 18 Push rod

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D033 EB07 3H060 AA09 BB03 CC02 CC11 CC40 DA03 DC05 DC09 DC10 DD02 DD16 DF09 FF07 GG06 HH04 HH19 3H106 DA05 DA23 DB02 DB12 DB23 DB32 DC09 DC18 DD09 EE04 EE36 EE48 GBKK GB08 GC08

Claims (3)

[Claims] 1. A housing having a pump port and an actuator port formed therein, a spool hole formed in the housing, a spool slidably guided by the spool hole, and one end face side of the spool. In addition, a control chamber that is always in communication with the pump port, a pilot chamber partitioned on the other end face side of the spool, and when the spool is moved by the pressure action between these control chambers and the pilot chamber, communicates with the control chamber, A tank port whose communication area with the control chamber is controlled in accordance with the amount of movement of the spool, and a variable throttle provided in a communication process for communicating the pump port with the actuator port, are constituent elements of the variable throttle. The aperture poppet member is provided with a poppet portion at one end thereof, and the poppet portion faces the control room side, The pressure action of the control chamber applies a force in the direction of reducing the throttle opening to the poppet, and a spring force in the direction of reducing the throttle opening acts on the throttle poppet member. In a flow control device provided with a push rod for applying a force in a direction opposite to the force of decreasing the direction, that is, a force for increasing the throttle opening degree to the throttle poppet member and a solenoid for applying a thrust to the push rod, When the annular groove having an enlarged diameter is provided at the connection portion of the spool hole to the tank port, a notch is provided at the end surface of the large-diameter portion on the pump port side of the spool guided by the spool hole so that the spool moves to the tank port side. A flow control device characterized in that the communication area to the tank port is increased with respect to the stroke. 2. The flow rate control device according to claim 1, wherein the notch has a cylindrical shape provided at an end surface of a large-diameter portion of the spool on the pump port side. 3. The flow rate control device according to claim 1, wherein the notch is formed by partially obliquely cutting an end surface of a large diameter portion of the spool on the pump port side.