JPS62184284A - Hydraulic changeover valve - Google Patents

Abstract

PURPOSE:To achieve the enhancement in tresponsiveness by providing a piezoelectric element by which the pressure in an oil pressure chamber is increased or decreased, and a throttling means by which the pressure in the oil pressure chamber is made approximately equal to the pressure inside a high-pressure introducing chamber within a prescribed time. CONSTITUTION:When a high voltage is instantaneously applied on an electrostriction type actuator 17, a piston 20 displaces upward to reduce the volume of an oil pressure chamber 21. Accordingly, the pressure inside the oil pressure chamber 21 rises suddenly to displace a spool valve 13 upward. As a result, the communication between a high-pressure port 11 and a control port 12 is cut off, and the control port 12 is communicated with a low-pressure port 31. And in this case, since the operating oil inside the oil pressure chamber 21 flows into a high-pressure introducing chamber 32 side through a throttle 27a and a communicating passage 27, the inclined surface 132 of the spool valve soon comes to be seated on a stepped part 151.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic switching valve, and is effective for use as a hydraulic switching valve provided in an actuator for controlling wheel cylinder pressure of an anti-skid control device of an automobile, for example. be.

[Conventional technology and problems]

Conventionally, as a hydraulic on-off valve provided in a hydraulic circuit, a solenoid valve is generally used, as disclosed in, for example, Japanese Patent Application Laid-Open No. 60-33158. A solenoid valve attracts a valve body using electromagnetic force generated when a solenoid coil is energized, and opens and closes a flow path by moving the valve body toward and away from a valve seat. However, due to the influence of the inductance of the solenoid coil, solenoid valves require a certain amount of time from the time they are energized until the valve body operates, and their responsiveness is not sufficient.

In addition, when a high-speed response is required, such as in an anti-skid control device, and it is necessary to open and close a flow path under high pressure, the solenoid coil must be enlarged to generate a large electromagnetic force.

On the other hand, it is conceivable to use an electrostrictive actuator with excellent responsiveness as a drive source for a hydraulic on-off valve, but even if this electrostrictive actuator is used, the valve opening degree is constant when energized, so anti-skid control For example, in a device where the control oil pressure changes significantly depending on the magnitude of the depression force on the brake pedal, there is a problem in that the characteristics of the oil pressure change change and the control accuracy is low.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic on-off valve that is small in size, has good responsiveness, and can exhibit stable characteristics even when the control oil pressure changes.

[Means for solving problems]

The housing that forms the outer shape of the hydraulic switching valve has a cylinder portion inside. The housing is formed with a high pressure port for guiding pressure oil from the hydraulic source into the cylinder section, a control port for communicating the inside of the cylinder section and the oil pressure consumption section, and a low pressure port for communicating the inside of the cylinder section and the oil reservoir section. do. A first valve seat is formed within the cylinder portion between the high pressure port and the control port, and a second valve seat is formed between the control port and the low pressure port. A spool valve is slidably disposed within the cylinder portion. A high pressure introduction chamber communicating with the high pressure port is formed at one end of the spool valve, and a hydraulic chamber whose pressure can be varied is formed at the other end. This pressure fluctuation in the hydraulic chamber is performed by a piezoelectric element that expands and contracts depending on the applied voltage. The spool valve is configured such that when the pressure in the hydraulic chamber is increased, the first valve portion seats on the first valve seat portion, and the second valve portion opens away from the second valve seat portion. Moving. Further, when the pressure in the hydraulic chamber is reduced, the spool valve moves so that the first valve part opens from the first valve seat part and the second valve part seats on the second valve seat part. do. This hydraulic switching valve has the above characteristics.

〔Example〕

FIG. 1 is a sectional view showing a hydraulic on-off valve according to an embodiment of the present invention. In this figure, the housing 10 has a high pressure port 11 that communicates with a high pressure source (not shown), a control port 12 that communicates with an oil pressure consumption source (not shown), and a low pressure port 31 that communicates with an oil reservoir (not shown). has. The high pressure port 11 and the control port 12, and the control port 12 and the low pressure ports 1-31 are communicated with each other or are blocked by a spool valve 13.

A piston cylinder 14 is disposed within the housing 10 and is connected to the piston cylinder 14 .
A spool cylinder 15 is formed having an inner diameter of approximately 174 mm. The end or opening of the piston cylinder 14 is closed by a cover 16. An electrostrictive actuator 17 formed by laminating a large number of piezoelectric elements has one end connected to a cover 16.
The piston cylinder 14 is fixedly fixed to the piston cylinder 14, and expands and contracts along the arrow T in the figure depending on the applied voltage. In order to apply a voltage to the electrostrictive actuator 17, the wire 18.
19 is provided passing through the cover 16. piston 20
is fixed to the end of the electrostrictive actuator 17 on the spool cylinder 15 side, and forms a hydraulic chamber 21 on the spool cylinder 15 side within the piston cylinder 14 . A Belleville spring 22 is provided in the hydraulic chamber 21 to bias the piston 20 toward the electrostrictive actuator 17 . The outer peripheral surface of the piston 20 is slidably supported on the wall surface of the piston cylinder 14 and sealed by an O-ring 23. Thus, the piston 20 is displaced in accordance with the expansion and contraction of the electrostrictive actuator 17, causing the hydraulic chamber 21 to expand and contract.

A cap 24 is arranged at the end of the spool cylinder 15, and this cap 24 forms a high pressure introduction chamber 32 inside, and further has a high pressure port 11 that communicates with this high pressure introduction chamber 32 and a hydraulic power source (not shown). There is. The spool valve 13 is slidably disposed within the spool cylinder 15, with one end facing the hydraulic chamber 21 and the other end facing the high pressure introduction chamber 32.

In the upper part of the spool cylinder 15 in the drawing, there is a medium diameter part 15a having a larger diameter than other parts, and this middle diameter part 15.
A large diameter portion 15b is formed which has a larger diameter than a. The low pressure boat 1-31 opens at a position facing the medium diameter portion 15a, and the control boat 31 opens at a position facing the large diameter portion 15b.

A bulging portion 13a having a larger diameter than other portions is formed in the upper part of the spool valve 13 in the figure.
This bulging portion 13a is located within the large diameter portion 15b. One slope 131 of this bulging portion 13a contacts and separates from the shoulder portion 24a of the cap 24, thereby communicating and blocking the high pressure port 11 and the control boat 12,
The control boat 1
2 and the low pressure boat 31 are communicated and cut off.

That is, one slope 131 of the bulging portion 13a functions as a first valve body, the shoulder portion 24a functions as a first valve seat, and the other surface 132 of the bulging portion 13a functions as a second valve body, and the shoulder portion 24a functions as a first valve seat. 151 functions as a second valve seat.

Hereinafter, - the slope 131 and the shoulder 24a will be referred to as the first valve and the other surface 1.
32 and the stepped portion 151 are referred to as a second valve.

A spring 25 is disposed within the high pressure introduction chamber 32 and biases the spool valve 13 toward the hydraulic chamber 21 side. Further, a communication passage 27 is formed in the center of the spool valve 13 to communicate the high pressure introduction chamber 32 and the hydraulic pressure chamber 21, and a throttle 27a is formed at the end of the communication passage 27 on the hydraulic chamber 21 side. It is formed.

In this embodiment, the amount of movement of the spool valve 13 is approximately 0.1 tm, and the amount of expansion and contraction of the piezoelectric element 17 is approximately 40 to 40 tm.
50 μ, the outer diameter of the piston 2o is 5.5 mm, the inner diameter of the shoulder portion 24a is 5.2 mm, the inner diameter of the stepped portion 151 is 5.8+n, the biasing force of the spring 25 is 500 g,
The diameter of the aperture 27a is 0.3 m. Further, the control boat 12 has a smaller inner diameter than the other ports, and in this embodiment, the inner diameter is 0.51 mm.

This embodiment operates as follows.

When no voltage is applied to the electrostrictive actuator 17, the spool valve 13 is urged downward in the figure by the spring 25 and oil pressure, so that the second valve closes and the first valve opens. That is, only the high pressure port 11 and the control boat 12 communicate with each other, and pressurized oil from the pressure source flows from the high pressure port 11 through the control boat 12 to the hydraulic pressure consumption section. In this state, the force that urges the spool valve 13 downward in the figure is due to the pressure receiving area on which the force that urges the spool valve 13 downward acts, in addition to the urging force of the spring 25, and the force that urges the spool valve 13 upward. The high-pressure boat 11 is affected by the difference in the pressure-receiving area on which the force acts, that is, the difference between the contact area SII between the surface 132 and the stepped portion 151 and the cross-sectional area S of the spool valve inserted into the spool cylinder 15. This is the size obtained by multiplying the difference between the pressure P inside the low pressure port 31 and the pressure PL inside the low pressure port 31. Thus, the outer surface 132 of the spool valve 13 maintains its seated state on the stepped portion 151.

When a high voltage is momentarily applied to the electrostrictive actuator 17, the piston 20 is displaced upward in the figure against the Belleville spring 22 due to the expansion of the electrostrictive actuator 17, and the volume of the hydraulic chamber 21 is reduced. let Therefore, the pressure within the hydraulic chamber 21 rises rapidly, and the spool valve 13 is displaced upward against the spring 25, as shown in FIG. At this time, the displacement of the piston 20 is minute, but since the spool cylinder 15 has a smaller cross-sectional area than the hydraulic chamber 21, the spool valve 13 is displaced relatively largely upwards, and one slope 131 becomes a shoulder. 24a, and the medical surface 132 is separated from the stepped portion 151. As a result, the high pressure port 11 and the control boat 12 are cut off, and the control port 12 and the low pressure port 31 are communicated with each other.

Therefore, the pressure within the hydraulic pressure consumption section flows out from the control boat 12 to the oil sump section via the low pressure port 31. Further, at this time, the hydraulic oil in the hydraulic chamber 21 flows to the high pressure introduction chamber 32 side through the throttle 27a and the communication passage 27. However, hydraulic chamber 2
The pressure inside the spool valve 13 gradually decreases, the spool valve 13 gradually moves downward, and the medical surface 132 seats on the stepped portion 151.

In this way, by momentarily applying a voltage to the electrostrictive actuator 17 (for example, applying a voltage of 500 V as a square wave), the first valve is temporarily closed, and the second valve is temporarily closed. Open the valve. The magnitude and time of opening of the second valve at this time are controlled by changing the magnitude of the voltage applied to the electrostrictive actuator 17 and the frequency of the rectangular wave.

In addition, when the first valve is closed, the second valve is open, and the control port 12 is in communication with the low pressure port 31, the load Fd acting on the spool 13 is as indicated by the plus sign upward in FIG. Take Fd=-fsp+ (PHPL) (SCSa)...
(i) Biasing force PH of the fsp spring 14: Pressure PL in the high pressure port 11: Pressure S in the low pressure boat 31: Contact area Sc between the slope 132 and shoulder 24a Represented by the membrane area of the Nispool valve 13 Ru. In this example, p,>p, ,s,>sA, so Pd=(PneePt,)(Sc-Sa)
> 0, and since P d > f sr, the position of the spool 13 is stabilized.

Next, when the high voltage applied to the piezoelectric element 17 is short-circuited or a reverse voltage is applied, the piezoelectric element 17 instantly contracts, the volume of the hydraulic chamber 21 increases, and the pressure inside the hydraulic chamber 21 decreases. do. As a result, the spool valve 13 moves downward in the figure as shown in FIG. That is, the high pressure port 11 and the control boat 12 communicate with each other, and pressurized oil from the hydraulic source flows from the high pressure port to the control boat 12.
After that, it is sent to the hydraulic pressure consumption part.

At this time, the load Fu acting on the spool valve 13 is expressed as Fu= fsP+ (
PH-Pt)(Ss-3c) (2).

However, S! l is the contact area between the surface 132 and the stepped portion 151. In this embodiment, since sl>se, P, and>PL, Fu>Q, and the position of the spool valve 13 is stabilized.

As described above, the switching from the increased pressure state in which the high pressure port 11 and the control port 12 are in communication to the reduced pressure state in which the control port 12 and the low pressure port 31 are in communication is achieved by applying a high voltage to the piezoelectric element 17. This is done by applying . Since the expansion of the piezoelectric element 17 at this time acts at extremely high speed, the hydraulic oil in the hydraulic chamber 21 cannot flow out to the high pressure introduction chamber 32 side via the throttle 27a and the communication path 27 in time, and A sudden pressure increase occurs. At this time, the downward load Fu' acting on the spool valve 13 is expressed as Fu' = fsp+ (Po - Pt) (Sll
Se)-ΔPu-3t...(3)
However, since the increase in ΔPu is extremely large, Fu
'<Q, and the spool valve 13 moves upward. The amount of movement at this time is approximately equal to the square of the ratio of the cross-sectional area SD of the piston 20 and the cross-sectional area S of the spool valve 13, assuming that the slope 131 does not come into contact with the shoulder 24a.
7 multiplied by the expansion amount β. In this example, approximately 0.
7 mm, the actual displacement of the spool valve is 0.2
Since the slope 131 is set sufficiently larger than that of the crane, the slope 131 easily comes into contact with the shoulder 24a. Then, the medical surface 132 is separated from the stepped portion 151, the control port 12 and the low pressure port 31 communicate with each other, and the pressure P in the control port 12 becomes approximately equal to the pressure PL in the low pressure port. At this time, the load Fd shown by the above-mentioned equation (i) acts on the spool valve 13 in the upward direction in the figure, and the seating becomes stable. Note that the pressure increase in the hydraulic chamber 21 flows out to the high pressure introduction chamber 32 via the throttle 27a and the communication passage 27, and the pressure in the hydraulic chamber 21 becomes P again.
becomes.

The transition from reduced pressure to increased pressure is performed by short-circuiting the high voltage of the piezoelectric element or by applying a reverse voltage. When the piezoelectric element instantaneously contracts and the pressure inside the oil chamber 21 drops rapidly, the upward load Fd' acting on the spool valve 13 becomes a pressure drop ΔP.
d as F d '=-fsF'' (p PL ) (sc
-3A)-ΔPd-3c...(4)
becomes. Here, since ΔPd shows a large value, Fd'
As a result, the spool valve 13 moves downward, the first valve opens, and the second valve closes. At this time, the pressure inside the hydraulic chamber 21 immediately becomes the pressure P inside the high pressure port 11.

The load of Fu shown by the above-mentioned equation (2) stably acts on the spool valve 13.

The application of high voltage, short circuit or reverse voltage to the piezoelectric element 10 is as short as several hundred microseconds, and the spool valve 1
The response of No. 3 can also provide a hydraulic switching valve that is excellent in extremely high-speed response of less than 1 m sec.

FIG. 4 shows an anti-skid device for an automobile incorporating the hydraulic switching valve according to the present invention.

The high pressure of the mask cylinder 100 is guided to the foil cylinder 200 via the electromagnetic valve 500, and is connected to the high pressure port 11 of the hydraulic switching valve 1 and the discharge side of the hydraulic pump 400 according to this embodiment. Further, the control port 12 of the hydraulic switching valve 1 is connected to a foil cylinder 200 which is a hydraulic pressure consumption part, and the low pressure port 31 is connected to a reservoir 300 which is an oil sump part and a suction side of a hydraulic pump 400.

The anti-skid device shown in Figure 4 performs good braking of the vehicle by appropriately controlling the wheel cylinder oil pressure.Although we will not discuss the details, we will briefly discuss an example of the operation of this hydraulic switching valve. .

As shown in FIG. 5, when the wheel cylinder oil pressure increases to a certain degree during braking, the control circuit shuts off the solenoid valve 500 and the hydraulic pump 400 starts rotating. At the same time, a high voltage is applied to the piezoelectric element 17 of the hydraulic switching valve 1. As a result, the wheel cylinder oil pressure, that is, the oil pressure in the control port 12, is discharged to the reservoir connected to the low pressure port 151, and pressure reduction is started. When the wheel cylinder oil pressure drops sufficiently, the piezoelectric element 17 of the oil pressure switching valve 1 is short-circuited, and the high pressure oil pumped up from the reservoir 300 by the hydraulic pump is exclusively applied to the wheel cylinder 200 and increased in pressure.

A control circuit (not shown) applies a high voltage 0N-O to the piezoelectric element of the hydraulic pressure switching valve 1 in order to increase and decrease the wheel cylinder oil pressure extremely quickly and precisely based on information such as the rotational state of the wheels.
Command as an FF command.

Next, a second embodiment of the present invention will be described. FIG. 6 is a sectional view showing the second embodiment. In this embodiment, the high pressure introduction chamber 32 communicating with the high pressure port 11 is connected to the spool valve 13.
A pressure PH' which is approximately equal to the pressure inside the high pressure port 11 is formed at the side circumference of the spool valve 13, and a pressure PH' which is approximately equal to the pressure inside the high pressure port 11 is formed at the end of the spool valve 13.
-11a, an equal pressure introduction chamber 321 is formed. Note that the end of the spool valve 13 is connected to the pressure equalization introduction chamber 3.
The area SA' facing 21 is equal to the area SA.

Here, if pH' = P, the operation of this embodiment is exactly the same as that of the previous embodiment, but when incorporated into an actual anti-skid control device, the pressure equalization port 11a is used for comparison of pulsation. By connecting it to a location with few targets, there is an effect of stabilizing the operation of the hydraulic switching valve even if there is considerable pulsation of the pressure PH in the high pressure port 11. That is, in the hydraulic switching valve according to the first embodiment, when an extremely rapid drop in hydraulic pressure occurs in the high pressure port 11, the pressure in the hydraulic chamber 21 becomes higher than the pressure in the high pressure introduction chamber 32, and the spool valve 13 is closed. However, in the second embodiment, a stable hydraulic pressure PH' is introduced to the pressure equalizing port 11a, so that the spool pressure due to fluctuations in the high pressure PH is prevented. There are seven advantages in that there is no load variation on the valve 13' and no malfunction of the hydraulic switching valve occurs.

FIG. 7 shows an anti-skid device incorporating a hydraulic switching valve 1' according to a second embodiment.

In this system, the oil pressure of the mask cylinder 100 is transferred to the pressure equalization introduction chamber 320 via the pressure equalization boat 11a of the hydraulic pressure switching valve 1'.
During control, this pressure equalization introduction chamber 321 is separated from the foil cylinder 200, hydraulic pump 400, etc., so that almost no hydraulic fluctuations in PH' occur.

The discharge side of the hydraulic pump 400 is guided to the high pressure boat 11, the control boat 12 is guided to the foil cylinder 200, and the low pressure boat 31 is guided to the suction side of the hydraulic pump 400 and a reserve tank 300 on the foil cylinder.

Further, a bypass valve controlled by the mask cylinder oil pressure is provided from the discharge side to the suction side of the hydraulic pump 400 to prevent an abnormally high pressure increase in the hydraulic pump 400.

An example of the operation of this anti-skid device is shown in FIG. In the operation example shown in the figure, the high voltage supplied to the piezoelectric element of the hydraulic switching valve 1' is set at a constant period τ, and the wheel cylinder hydraulic pressure is increased or decreased by changing the time ratio between the high voltage state and the short circuit state. Avoiding wheel skid during control.

〔Effect of the invention〕

As explained above, by using the hydraulic switching valve of the present invention, hydraulic pressure can be switched in a small size and with high responsiveness. In particular, when the present invention is incorporated into a device that requires high precision and high responsiveness, such as an anti-skid device for automobiles, the above requirements can be fully satisfied.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the first embodiment, Figures 2 and 3 are schematic sectional views explaining the operation, Figure 4 is a hydraulic circuit diagram, and Figure 5 is a hydraulic circuit diagram.
6 is a sectional view showing the second embodiment, FIG. 7 is a hydraulic circuit diagram, and FIG. 8 is an explanatory diagram of operation. 11... High pressure boat, 12... Control boat, 13.
...Spool valve, 17...Piezoelectric element, 24a...
- Shoulder part (first valve seat part), 131... slope part (first valve part), 132... slope part (second valve part), 151... step part (second valve seat part). Representative Patent Attorney Takashi Okabe Figure 1 Figure 5 Figure 7 Figure 8

Claims (1)

[Scope of Claims] (a) A housing that forms the outer shape of a hydraulic switching valve and has a cylinder section inside; (b) A high pressure formed in the housing for guiding hydraulic pressure from a hydraulic source into the cylinder section. (c) a control port that communicates between the inside of the cylinder section and the oil pressure consumption section; (d) a low pressure port that communicates the inside of the cylinder section and the oil reservoir section; (e) a control port that communicates between the inside of the cylinder section and the oil reservoir section; (f) a second valve seat portion formed within the cylinder portion and between the control port and the low pressure port; (g) A first valve seat that is slidably disposed within the cylinder portion, has a high pressure introduction chamber communicating with the high pressure port at one end side, a hydraulic chamber at the other end side, and is seated on the first valve seat portion. a spool valve having a first valve seat portion and a second valve portion seated on the second valve seat portion; a piezoelectric element that increases or decreases the pressure in the hydraulic chamber; (i) a restricting means that makes the pressure in the hydraulic chamber substantially equal to the pressure in the high pressure introduction chamber within a predetermined time; (j) When the pressure of (k) When the pressure in the hydraulic chamber is reduced, the spool valve moves the first valve part away from the first valve part.
A hydraulic switching valve characterized by being moved in a direction in which the second valve part is moved away from the valve seat part and seated on the second valve seat part.