JP2816898B2 - Flow control valve - Google Patents

Description

The present invention relates to a flow control valve suitable for controlling, for example, a hydraulic clutch.

[Conventional technology and its technical problems]

Regarding the control of an automatic hydraulic clutch that shifts by connecting and disconnecting the gear train with a hydraulic clutch, the volume of the clutch pack (oil chamber of the hydraulic cylinder) is quickly filled with hydraulic pressure first, and the control area, that is, the half-connected state Good resolution is required in the range up to connection completion. Realizing such characteristics only with the proportional solenoid valve is originally excellent in resolution as a pilot element, but it is unreasonable with this kind of valve having a small flow rate, and the power consumption increases.
Therefore, as a countermeasure, Japanese Patent Application Laid-Open No. 62-224730 and Japanese Utility Model Application Laid-Open No. 1-154335 propose a flow control valve using an electromagnetic proportional valve and a detection valve.

These in the prior art, as shown in FIG. 6, incorporated a solenoid proportional valve V ₁ is detected valve V ₂ and the first body BD ₁ as valve separately from each other in the second body BD _2, and the electromagnetic proportional Both input ports P ₁ and P ₂ of the valve V ₁ and the detection valve V ₂ are connected to each other and connected to a hydraulic supply via piping, and both output ports A of the solenoid proportional valve V ₁ and the detection valve V _{2 1,} a ₂ was also adapted to be connected to the clutch pack C through the pipe are connected to each other.

Specifically, the solenoid proportional valve V ₁ moves the spool s ₁ disposed in the spool hole of the first body BD ₁ and the spool s against the spring sp ₁ in accordance with the magnitude of the supply current, Proportional solenoid that controls the opening between input and output ports
S ₀ , and a detection valve V ₂ is disposed in a spool hole of the second body BD ₂ and opens and closes between an input port and an output port.
and s _2, has a spring sp ₂ return urges the spool s ₂ to the closing side, and the aperture e provided in the flow path of the proportional solenoid valve V ₁ output port downstream the diaphragm e It was adapted to move in the opening direction against the biasing force of the spring sp ₂ returns the spool s ₂ by the pressure differential across the.

Then, when control of the hydraulic clutch, first a proportional solenoid S ₀ to the proportional solenoid valve V ₁ is fully opened. Thus, pressure oil flows into the clutch pack through the electromagnetic proportional valve V _1, the pressure differential across the e stop at this time occurs, even against the spring sp ₁ return spool s ₁ sensing valve V ₂ The clutch pack C is filled with a large amount of pressure oil. The clutch pack is actuated, the increase in pressure in the clutch pack becomes a half clutch state is transferred to the diaphragm e, the pressure difference across the diaphragm is reduced, the spool s ₂ of detecting valve V ₂
It is returned to the closed position by a spring sp ₂ return. By controlling the current supplied to the proportional solenoid valve V ₁ detects this stroke, flow to the clutch pack C in accordance with the opening degree of the spool s ₁ is controlled, the clutch is shifted to the connected state.

However, in the prior art, as before the proportional solenoid valve V ₁ and detecting valve V ₂ is not a separate valve mechanism, since they are incorporated to each body BD _1, BD _2, complicated structure Large and heavy. Accordingly, there is no problem in the case of a large construction vehicle which can take a large space for installation and installation, but there is a problem that it is difficult to apply to a small vehicle such as a passenger car.

Further, in the prior art, the spool position proportional solenoid valve V ₁ is either a P-A connection and A-T connection. Therefore, while the detecting valve V ₂ satisfies the pressurized oil to the clutch pack activated (for Holding opens the solenoid proportional valves V ₁ power consumption increases, normally, are closed), the electromagnetic and the a → T proportional valve V ₁ is opened, therefore, a part of pressure oil from the input port of the detecting valve will continuously flow into the tank. For this reason, the filling efficiency is poor and there is a problem in terms of responsiveness.

[Means for solving the problem]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problems, and an object thereof is to fill a pressure chamber of an actuator with oil, as represented by control of a hydraulic clutch, and then pressurize the pressure chamber. After the load pressure rises due to the force from the work piece, the flow control that increases the pressure in the pressure chamber proportionally against the load pressure can be realized with a very small and lightweight structure. Another object of the present invention is to provide a novel flow control valve capable of realizing good responsiveness.

In order to achieve the above object, the present invention is to incorporate a solenoid proportional valve and a detection valve into a spool hole of one body in the form of a double-barrel spool and operate them in a related manner.

That is, a feature of the present invention is that a body formed with an input port, an output port and a tank port in a relationship intersecting the spool hole and the spool hole, and a cylindrical shape slidably inserted into the spool hole. A first spool, and a second spool inserted into the first spool so as to be relatively movable and moved by a solenoid unit;
A spool has input, output, and tank through-holes corresponding to the ports, and opens and closes between the input and output ports of the body between the input and output through-holes on the outside. A land portion, and a restrictor for restricting the flow of pressure oil from the input port to the output port, and an inner portion having a smaller pressure receiving area than the land portion is provided inside the portion between the output through hole and the tank through hole. A cylinder chamber having a pressure receiving surface in a region deviated from the input port, the cylinder chamber being in communication with an external low pressure chamber through a small hole;
A main land portion that normally shuts off between the input through-hole and the output through-hole of the first spool, and a leak that underlaps the inward land and has a smaller pressure receiving area than the main land portion in a normal state. The structure has a prevention land portion and a piston land portion located in the cylinder chamber.

[Action]

Under normal conditions, the first spool and the second spool are returned by the springs for setting the initial position, respectively, and the input and output holes provided in the first spool are blocked by the main land provided in the second spool. The input port and the output port provided on the body are shut off by the land of the first spool. On the other hand, since the land for preventing leakage of the second spool is located on the inward land and the underlap, the output port of the body and the tank port communicate with each other. Therefore, the pressure oil from the hydraulic pressure source is not supplied to the output port, and the oil of the actuator is returned to the tank.

In this state, when a large current flows through the solenoid, the second spool moves (fully opens). That is, the piston land portion of the second spool rapidly moves in the axial direction in the cylinder chamber of the first spool. At this time, the oil filled in the cylinder chamber is not immediately discharged from the pores to the low-pressure chamber due to viscous resistance, so that pressure is generated in the cylinder chamber and presses the pressure receiving surface of the first spool. Thereby, the first spool also moves (opens) in the spool hole almost simultaneously with the movement of the second spool. As a result, the land portion of the first spool is separated from the switching convex wall of the spool hole, and the pressure oil flows from the input port of the body to the output port via the throttle, and is sent to the actuator.

When the first spool moves as described above, the current applied to the solenoid portion is immediately reduced. Then, the second spool returns while being guided by the inner diameter of the first spool.
Since the spool is held in the valve-open state by the pressure difference generated before and after the throttle portion in the output port area, the supply of the pressure oil is continued. At this time, with the return of the second spool, the land for preventing leakage of the second spool wraps around the inward land of the first spool. Therefore, the oil supply is performed in a state where the communication between the output through-hole and the tank through-hole is cut off (the output port and the tank port are cut off), and the pressure oil can be efficiently sent to the actuator.

When the volume of the actuator is filled with pressure oil,
Pressure starts to build up at the body output port. The pressure receiving area of the inward land of the first spool is smaller than the pressure receiving area of the land portion, and the pressure difference before and after the constriction gradually disappears. Therefore, the first spool is moved to the closing side due to the pressure receiving area difference.

If the energization to the solenoid portion is controlled proportionally from this state, the second spool moves according to the energization amount, and the flow rate is controlled with good resolution. At this time, the first spool is kept closed by the pressure receiving area difference.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 to 4 show one embodiment of a flow control valve according to the present invention.

Reference numeral 1 denotes a body, reference numeral 2 denotes a first spool for detection, and reference numeral 3 denotes a second spool for electromagnetic proportionality having a shaft shape. The second spool 3 is coaxially inserted into the first spool 2 and is moved by a solenoid unit 5 fixed to the right end of the body 1.

More specifically, first, the body 1 is provided with a spool hole in the longitudinal direction.
10, the left end side of the spool hole 10 penetrates, and the plug 11 is fitted therein. Of course, it may be a blind hole.

The body 1 has an input port P connected to a hydraulic pressure source 4.
And an output port A connected to an actuator such as a clutch pack C, and a tank port T connected to a tank.
Are formed so as to intersect with the spool hole 10 and at a predetermined interval from each other.

Each of the ports includes a groove, and at least the output port A of the ports is formed as a dome-shaped wide groove as shown in FIG. Near the input port, an annular concave portion 12 for slidingly guiding the throttle portion is provided adjacently, and an annular switching convex wall is provided in a spool hole following the annular concave portion 12.
13 are protrudingly formed. Further, a cylindrical hole 15 having a large diameter is formed in a spool hole portion on the right side of the input port P via an annular guide convex wall 14.

Next, the first spool 2 is, as shown in FIG.
The body 1 is slidably fitted in a spool hole 10. The first spool 2 has a large-diameter portion 2a slidably in contact with the guide convex wall 14 formed over a required length from the right end, and a ring-shaped drain chamber is formed between the first spool 2 and the cylindrical hole 15 by the large-diameter portion 2a.
Dr has been defined.

Further, a land portion 2b which comes into contact with and separates from the switching convex wall 13 is provided at a position at a predetermined distance from the end of the large diameter portion 2a.
On the left side of the land portion 2b, there is formed a middle diameter portion 2c which is always in sliding contact with a spool hole between the output port A and the tank port T. Further, on the left side, a tip portion 2e having a smaller diameter is formed through a small diameter portion 2d, and the tip portion 2e fits in the tip end region of the spool hole, and the tip portion 2e and the small diameter portion 2d are formed. The movement is restricted by contacting the stepped portion 2f, which forms the boundary of, with the left wall of the tank port T.

A plurality of input through holes 20 are provided between the large diameter portion 2a and the land portion 2b, a plurality of output through holes 21 are provided in the middle diameter portion 2c, and a plurality of output through holes 21 are provided in the small diameter portion 2d. Is a plurality of tank holes 22
Are formed penetrating through the cylindrical wall.

Medium diameter portion 2c between the end of the output through hole 21 and the land portion 2b
On the outer periphery, a ring-shaped throttle member 7 that is in sliding contact with the annular concave portion 12 is integrally fixed by press-fitting or the like. As shown in FIG. A hole 70 is provided. The throttle hole 70 allows the pressure oil from the input port P to the output port A to flow favorably when the first spool 2 is opened, and the pressure on the input port side increases when the second spool 3 is fully opened. This is to create a differential pressure that is higher than 50% of the total area of the throttle member 7.
% Or less, preferably about 40 to 47%. The throttle member 7 is provided with the first spool 2 in the spool hole 10.
Is inserted into the output port A in advance when the
Assembly is easy because the spool 2 is integrated by fitting.

On the other hand, on the inner side of the first spool 2, an enlarged hole 23 having a step portion 24 as a pressure receiving portion is formed in a region of the large diameter portion 2a,
The enlarged hole 23 communicates with the drain chamber Dr through a small hole 230 at a position near the left end. A straight medium-diameter hole 25 is formed in a region extending from the step portion 24 to the land portion 2b. The input through-hole 20 is provided at the position of the medium-diameter hole 25.

A first ring groove 26 is formed on the left side of the middle diameter hole 25,
Here, the output through-hole 21 is provided. On the left side of the first ring groove 26 is a small diameter hole 27 having a smaller diameter than the medium diameter hole 25 up to the tip.
A second ring groove 28 is formed in the starting end region, that is, in the region between the output port A and the tank port T so as to have an inward land 29.

The first spool 2 is provided with a spring 6 having almost no setting force for setting an initial position between the end face of the tip 2e and the bottom of the spool hole (plug 11 in the drawing). As a result, the end face of the large-diameter portion 2a is brought into contact with the housing 5a of the solenoid portion 5, and in this state, the input through hole 20 is connected to the input port P, the output through hole 21 is connected to the output port A, and the tank through hole is used. Numerals 22 face the tank ports T, respectively, and the land portions 2b overlap the switching convex walls 13 to block the input port P and the output port A.

Incidentally, the pressure-receiving area S ₁ of the land portion 2b, it is necessary to be made larger than the pressure receiving area S ₂ of the inward land portion 29.

Next, the second spool 3 includes, from the right end side to the left end side, a land portion 3a for a piston that is in sliding contact with the enlarged hole 23;
A partition land 3b for slidingly contacting the medium-diameter hole 25 to the right of the input through hole 20 and defining a cylinder chamber Cr in an enlarged hole between the piston land 3a; The input through hole 20 and the output through hole 21 are in sliding contact with the medium diameter hole 25 on the left side of the hole 20.
Main land portion 3c for opening and closing the space, and the inward land 29
3d, and an end land 3e slidingly contacting the small-diameter hole 27. The main land 3c has a larger pressure receiving area than the leakage prevention land 3d.

The end land portion 3e has a concave portion 31 on the end surface thereof, and is formed by a spring 8 having little set force for initial position setting interposed between the concave portion 31 and the bottom of the spool hole (the plug 11 in the drawing). The two spools 3 are in contact with the housing 5a of the right end solenoid portion 5. This state is a valve closing state. In this state, the main land portion 3c overlaps with the medium diameter hole 25 adjacent to the first ring groove 26, and the leakage prevention land portion 3d is
And is located in the second ring groove 28.

The solenoid part 5 includes a housing 5a as well as a well-known one.
The armature 5c is disposed inside the solenoid 5b, and the armature 5c is in contact with the head of the second spool 3 via a strong pressing spring 5d disposed in the shaft hole 50. The solenoid 5b is electrically connected to an external controller 5e, and is controlled by the controller 5e, for example, in an energization pattern as shown in FIG.

A switch 9 for detecting the movement of the first spool 2, ie, filling, is embedded in an end face of the housing 5 a corresponding to the right end face of the first spool 2, and is electrically connected to the controller 5 e. This switch 9
Preferably, a mechanical-electrical conversion element such as a piezoelectric element is used.

The shaft hole 50 is connected to the drain chamber Dr by oil guide holes 51, 51.
With the solenoid 5b
Is oil cooled. The spool 3 has a drain through hole 32 in the axial direction, and the through hole 32 branches the discharge hole 33 to a portion facing the tank port T. Therefore, the drain oil serving as an oil cooler flows from the shaft hole 50 through the through hole 32 and the discharge hole 33 to the tank port T.

[Operation of the embodiment]

In the state shown in FIG. 1, the first spool 2 is closed, and the second spool is also closed without energizing the solenoid 5b. At this time, the land portion 2a of the first spool 2 overlaps the switching convex wall 13 of the body 1, and the main land portion 3c provided on the second spool 3
, The input port P and the output port A are closed.

On the other hand, at this time, the land portion 3d for preventing leakage of the second spool 3 is located in the second ring groove 28 and the inward land portion 29
Are in an underlap state, the output port P and the tank port T communicate with each other through an internal passage formed by the first spool 2 and the second spool 3. Therefore, the oil of the actuator C is smoothly returned to the tank.

In this state, as shown in the step of FIG. 5, when a large current is first applied to the solenoid 5b, the armature 5c is lifted to the maximum, and the second spool 3 is rapidly moved to the fully opened position by the pressing spring 5d. Since the second spool 3 has a piston land 3a on the right end side, the piston land 3a
The sudden movement of 3a to the left reduces the volume of the cylinder chamber Cr. Oil filled in cylinder chamber Cr is pores
An outflow from 230 to the drain chamber Dr is attempted, but the outflow is delayed by viscous resistance, so that a pressure is generated in the cylinder chamber Cr, and the pressure acts on the step portion 24.

Therefore, the first spool 2 moves to the left integrally and almost simultaneously with the movement of the second spool 3, and the land portion 2b is separated from the switching convex wall 13. As a result, the pressure oil from the pressure source 4 flows out of the gap between the land portion 2b and the switching convex wall 13 and flows to the output port A through the throttle hole 70.
As a result, a pressure difference occurs before and after the throttle member 7, so that the first spool 2 moves until the left end side step 2 f contacts the left wall of the tank port T. Therefore, the pressure oil is sent to the actuator 4 at a large flow rate.

Next, the current applied to the solenoid 5b is reduced as shown in FIG. Thereby, the second spool 3 is returned. FIG. 4 shows this state.
The first spool 2 is kept in the open state by the flow force passing through the pressure port, so that the pressure oil flows from the input port P to the output port A as shown by the arrow in FIG. Fulfill. At this time, the land 3d for preventing leakage of the second spool 3 is in contact with the inward land 29. Therefore, the output port A and the tank port T are shut off, and the pressure oil on the output port A side does not leak to the tank. Therefore, the pressure oil can be efficiently supplied to the actuator C, and the filling time can be further reduced.

Thus, when the volume of the actuator C is filled with the pressure oil, the pressure P ₂ starts to rise at the output port A. The hydraulic clutch is in a semi-connected state. The pressure P ₂ of the output port A acts to prevent land portion 3d leakage between the main land portion 3c of the second spool 3, for the former pressure receiving area larger than that of the latter, the second spool 3 is not moved. Further, the pressure receiving area S ₂ of the pressure receiving area S ₁ and the inward land portion 29 of the first spool 2 land portion 2b have a relationship of S _1> S _2. Therefore, the first spool 2 starts moving rightward due to the pressure receiving area difference. And the pressure oil flows from the input port P with the movement to the output port A is throttled, the increased pressure P ₂ of output port A, the pressure P ₁ on the upstream side and the downstream side of the throttle member 7 and P ₂
Are almost equal. Therefore, the first spool 2 is pushed into the pressure P ₀ is high despite the right side of the input port P. As a result, the land 2b comes into contact with the switching convex wall 13, and the connection between the input port P and the output port A is cut off.

When the first spool 2 returns to the initial position in this manner, the filling detection switch 9 embedded in the end face of the housing 5a.
And a control start signal is sent to the controller 5e. As a result, proportional control is performed so that the current value dropped as shown in FIG. 4 gradually increases. As a result, only the second spool 3 is gradually moved to the left from the state shown in FIG. 1, the main land portion 3c is separated from the medium-diameter hole 25,
The pressurized oil flows from the input through hole 20 through the first spool 2 to the output port A through the output through hole 21. In this case, the second
Since the spool 3 has a small diameter, the resolution is good and good control can be performed.

When a piezoelectric element is used as the filling detection switch 9, the signal is sent to the controller 5e after being distorted by the contact force of the first spool 2 and converted into an electromotive force. Since this method is not a switch due to mechanical movement as in the prior art, there are no problems such as poor contact or movement delay due to wear of the friction portion, and the reliability is high. Further, since the structure is simplified, further miniaturization can be realized. Further, not only simple on / off operation, but also the pressure (eg, clutch pressure) of the actuator 7C acting in the axial direction of the first spool 2 can be taken out at any time, which is advantageous in performing precise control.

The lower limit holding of the current value during the filling is not a control current value for preventing leakage from the output port to the tank port in the present invention, but for smoothing the rising of the proportional control as the next step, Therefore, the minimum necessary weak current value is sufficient.

The entry of dust that adversely affects the operation of the solenoid unit 5 can be prevented by the presence of the partition land 3b and the piston land 3a. However, if necessary, the left side of the land portion 3a for the piston and the large diameter portion 2a of the first spool 2 may be used.
Of course, may be connected by a diaphragm.

〔The invention's effect〕

According to the present invention described above, since the spool for electromagnetic proportional and the spool for detection are incorporated in the body as a double-barrel type, the structure is very small and lightweight while having both functions of electromagnetic proportional and detection. Therefore, the present invention can be applied to a hydraulic clutch control means of a small vehicle and the like. In addition, oil leakage from an output port to a tank port does not occur at the time of filling the actuator with oil. Excellent effects such as good responsiveness can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a flow control valve according to the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. FIG. 4 is an exploded perspective view, FIG. 4 is a cross-sectional view showing a state when a detection valve is operated, FIG. 5 is an explanatory view illustrating a current control pattern when clutch control is performed according to the present invention, and FIG. 6 is a conventional flow control valve. FIG. 1 ... body, 2 ... first cylindrical spool, 2a ... large diameter portion, 2b ... land portion, 3 ... second spool, 3a ... piston land portion, 3c ... main land portion, 3d: Leak prevention land, 5: Solenoid, 6, 8: Spring, 7
…… Aperture member, 10 …… Spool hole, 24 …… Stepped part, 29 ……
Inward land, 70 …… Draw hole, 230 …… Pore, Cr ……
Cylinder chamber, Dr ... Drain chamber

Claims (1)

(57) [Claims] A body formed with an input port, an output port, and a tank port in a relationship intersecting with the spool hole; a first cylindrical spool slidably inserted into the spool hole; A second spool which is relatively movably inserted into the first spool and is moved by a solenoid unit, wherein the cylindrical first spool has input, output and tank through holes corresponding to the ports. With
On the outside, between the input and output holes, a land portion that opens and closes between the input port and the output port of the body, and a restrictor that restricts the flow of pressurized oil from the input port to the output port, On the inside, a cylinder chamber having a pressure receiving surface is provided in a region between the output through hole and the tank through hole, the inward land having a smaller pressure receiving area than the land portion, and a region outside the input port. The cylinder chamber communicates with an external low-pressure chamber through a small hole. The second spool has a main land portion that normally shuts off between the input through hole and the output through hole of the first spool. A flow control valve, comprising: a land portion for leakage prevention that underlaps an inward land and has a pressure receiving area smaller than that of the main land portion, and a land portion for a piston located in the cylinder chamber.