JPH02163581A - Electric selector valve - Google Patents

Abstract

PURPOSE:To reduce the dimension of the selector valve and lower the driving voltage by forming a hydraulic chamber in which a discharge flow passage is opened and closed by the action of a bimorph electric strain element, onto the edge surface of one or both of the spools set at a neutral position by a spring. CONSTITUTION:A spool 12 having lands 12a-12d is installed inside a valve body 10, and hydraulic chambers 13 and 14 are formed at the both edges, and a pilot hydraulic pressure is supplied through a throttle 15, and the spool is held at a neutral position by springs 16a and 16b. The hydraulic chambers 13 and 14 are equipped with discharge flow passages communicating to the communication passages 19 and 20 through the bimorph electric strain elements 21 and 22 for closing the opened port parts of the nozzles 17 and 18 in the nonelectric conduction state. When the electric conduction to the bimorph electric strain element is in cut-off state, each hydraulic pressure at the both edges is balanced, and the neutral state is maintained, and when a voltage is applied onto one of the bimorph electric strain element, the discharge passage is opened to shift a spool. Therefore, the device can be made small-sized in comparison with the conventional device using a solenoid, and the consumption of electric current can be reduced to nearly zero, and the control at the neutral position is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electric switching valve that uses a bimorph electrostrictive element to switch the flow direction of fluid.

(Prior art) Conventionally, this type of electric switching valve generally has a 1-0
There is an electromagnetic switching valve shown in the figure.

In Fig. 1-0, reference numeral 1 denotes a valve body in which a switching spool 2 is slidably built in, and electromagnetic solenoids 3 and 4 are arranged on both sides of the switching spool 2.
, 4 are not energized, the switching spool 2 is placed in the neutral position by the pressure of the spring as shown in the figure, and when the electromagnetic solenoid 3 or 4 is energized, the plunger 5 or 6 pushes the switching spool 2, and the switching spool 2 is placed in the left or right switching position. Switch to .

(Problem to be Solved by the Invention) However, in such conventional electric switching valves using electromagnetic solenoids, the electromagnetic solenoid occupies a large proportion of the unit, making the switching valve large. In addition, since the electromagnetic solenoid continues to be energized in the switching state, there is a problem of high current consumption and heat generation.Furthermore, there is the problem that the switching spool cannot be controlled at an intermediate position during switching. there were.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and is an electric switching valve that switches the direction of fluid flow. A spool liquid chamber to which pilot liquid pressure is supplied is formed on one or both sides of the switching spool, and a discharge passage is provided that communicates with the tank line from this spool liquid chamber, and this discharge passage is opened and closed by a bimorph electrostrictive element. It is configured to control.

(Function) According to the configuration of the present invention, when the bimorph electrostrictive element is not energized, the discharge flow path is closed, thereby balancing the hydraulic pressure at both ends of the switching spool, and the switching spool is moved by the pressure of the spring. Placed in the neutral position, when the bimorph electrostrictive element is energized, the discharge channel of the displacement chamber due to the electrostrictive phenomenon of the element is opened, the pilot hydraulic pressure is released, and the spool is moved to the switching position.

(Effects of the Invention) The electric switching valve of the present invention having the above configuration and operation provides the following effects.

First, the bebimorph electrostrictive element is extremely small compared to an electromagnetic solenoid, so the switching valve can be made significantly smaller and lighter.

Secondly, since the structure is simple, there is no failure and it is almost maintenance-free.

Thirdly, the bimorph electrostrictive element can be driven by applying as much voltage as possible, and current consumption is approximately zero, making it possible to reduce power consumption and prevent heat generation.

Fourthly, since the bimorph electrostrictive element can change the amount of displacement depending on the applied voltage, it can be controlled at an intermediate position during switching.

(Embodiment) FIG. 1 is a sectional view showing an embodiment of the present invention, taking a four-way switching valve as an example.

First, to explain the configuration, 10 is a valve body, a switching spool 12 is slidably provided inside the valve body 0, and lands 12a, 12 are provided at four locations on the switching spool 12.
b, 12c and 12d. Switching spool 1
Spool hydraulic pressure chambers 13 and 14 are formed at both ends of the pump 2, and hydraulic pressure from the pump line P is supplied to each of the spool hydraulic pressure chambers 13 and 14 via a throttle 15 as pilot hydraulic pressure. Further, springs 16a, 16b for maintaining the switching spool 12 in a neutral position are housed in each of the spool hydraulic pressure chambers 13 and 14.

There are nozzles 17 and 18 on the outside of the spool hydraulic pressure chambers 13 and 14.
A discharge flow path leading to the tank line T is formed with a communication path 19.20, and bimorph electrostrictive elements 21.22 with the nozzle openings closed as shown in the drawing are connected to the tips of the nozzles 17 and 18 in a non-energized state. The bimorph element 21.22 is mounted with cantilever support by the fixed part 23.24, and the bimorph element 21.22 is attached to a pair of lead terminal wires 25a, 25b and 26a, 26b.
This allows driving voltage to be applied from the outside.

In addition, switching lines A and B are formed in the valve body 10 in addition to a tank line T that communicates with a pump line P1 tank that supplies pump hydraulic pressure, and switching lines A and B are connected to pump lines P and B at the neutral position shown in the figure. It is in a state where it is disconnected from the tank line T.

FIG. 2 shows the amount of displacement with respect to the driving voltage of the bimorph electrostrictive element 21.22 having the nozzle flapper structure shown in the embodiment of FIG.
The amount of displacement increases approximately in proportion to the voltage applied to 2. Note that when the voltage is lowered after applying the driving voltage by -degree, the displacement amount changes with hysteresis as shown by the broken line.

Further, the bimorph electrostrictive element can be displaced by only applying a driving voltage, and almost no current consumption flows.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, in the illustrated neutral position, the bimorph electrostrictive element 2
No drive voltage is applied to nozzle 17.1.22.
18 and closes off the discharge flow path to the tank line T. For this reason, the spool hydraulic chambers 1.3, 1.
The hydraulic pressure from the pump line P acts on the springs 16 through the throttle 15, so that the hydraulic pressure is balanced, and the springs 16 on both sides
．． 17, the switching spool 1-2 is placed in the neutral position. In this neutral position, the land 12b of the switching spool 12
.

12c closes switching lines A and B, and also disconnects pump line P and tank line T.

Next, if a driving voltage is externally applied to the bimorph electrostrictive element 21 provided on the left side via the lead wires 25a and 25b, the bimorph electrostrictive element 21 curves outward as shown in FIG. Open 1-7. This nozzle 1
7 opens, the spool hydraulic pressure chamber 1-3 communicates with the tank line T via the communication path 19, and liquid flows into the spool hydraulic pressure chamber 13 from the pump line P via the throttle 1-5. The hydraulic pressure in the hydraulic chamber 13 is lower than the hydraulic pressure in the pump line P by the differential pressure generated by the throttle 15.

On the other hand, since the hydraulic pressure of the pump line P acts directly on the spool hydraulic pressure chamber 14 on the right side, the switching spool 12 is pushed by a force corresponding to the differential pressure between the spool hydraulic pressure chambers 13 and 1-4, and The switching state is such that the pump line P communicates with the switching line A and the switching line B communicates with the tank line T.

Such a switching operation also occurs when a driving voltage is applied to the right bimorph electrostrictive element 22.
4 communicates with the tank line T, and the switching spool 12 is pushed to the right by a force based on the differential pressure between the spool hydraulic pressure chamber 14 determined by the throttle 15 and the spool hydraulic pressure chamber 13 which receives the hydraulic pressure of the pump line P. switch pump line P to line B.
A switching state is obtained in which the switching line A is connected to the tank line T and the switching line A is connected to the tank line T.

FIG. 4 is an explanatory diagram showing another embodiment of the nozzle flapper structure using the bimorph electrostrictive element used in the embodiment of FIG. It is characterized in that the nozzle opening is closed by the displacement at the same time.

In FIG. 4, the flapper member 27 has a sandwich structure in which it is sandwiched between a pair of bimorph electrostrictive elements 28 and 29, and is cantilevered on the valve body 10 by a fixing portion 31. The nozzle 3 faces the tip of the flapper member 27.
0 is provided in the nozzle 30, and a nozzle hole 31 with a diameter d is opened from the spool hydraulic pressure chamber 33.
A diametrical flat surface 32 is formed at the opening. Here, the diameter of the flat surface 32 is more than twice the diameter d of the nozzle hole 31, and the flapper member 2
When the gap between the nozzle 7 and the flat surface 32 becomes narrow, the nozzle 3
0 can be closed.

That is, when a driving voltage is applied to the bimorph electrostrictive elements 28 and 29, a displacement is obtained that presses the flapper member 27 onto the flat surface 32 of the nozzle 30, and this flapper member 27 is pressed against the flat surface 32 of the nozzle 30.
When the gap between the nozzle 30 and the flat surface 32 becomes narrow due to the displacement of 7, as shown in FIG. At this point, the pressure is positive, but as it moves outward, it becomes negative pressure and an adsorption force is generated. Therefore, the closure of the nozzle 30 by the flapper member 27 is realized by the displacement by the bimorph electrostrictive elements 28 and 29 and the suction force obtained by the jet from the nozzle hole 31.
．． Even if the driving force of the flapper member 27 by the flapper member 29 is small, the nozzle 30 can be reliably closed due to the suction force generated by the jet stream.

FIG. 6 is a sectional view showing another embodiment of the present invention having a pilot hydraulic pressure switching mechanism with a flapper structure using a bimorph electrostrictive element only on one side of the switching spool;
Corresponds to a conventional one-way electromagnetic solenoid switching valve.

The embodiment shown in FIG. 6 differs only in that the spring 1.6b that returns the right side of the switching spool 12 to the neutral position is removed, and the other components are the same as the bimorph electrostrictive element 2.
At 2, a nozzle flapper structure is provided for opening and closing the discharge passage of the spool hydraulic pressure chamber 14. On the other hand, on the left side of the switching spool 12, a hydraulic pressure chamber 13 communicating with the tank line T is formed, and only a spring 16a for returning the switching spool 2 to the neutral position is incorporated in the spool hydraulic pressure chambers 1 and 3. ing.

The switching operation of the embodiment shown in FIG. 6 is such that when no driving voltage is applied to the bimorph electrostrictive element 22, the bimorph electrostrictive element 22 is fixed to the opening of the nozzle 18 and closes the discharge flow path. The spool hydraulic pressure chamber 14 has an orifice 15.
The hydraulic pressure of the pump line P acts as it is through the spring 13 on the left side to keep the switching spool 12 in the neutral position.

Next, when a driving voltage is applied to the bimorph electrostrictive element 22, the bimorph electrostrictive element 22 curves outward to open the nozzle 18 as shown in the figure, and the hydraulic pressure in the spool hydraulic chamber 1-4 decreases, causing the spring to open. Switching spool 12 by pressing 16
moves to the right as shown in the figure, connecting the pump line P to the switching line A and connecting the switching line B to the tank line T.
A switching state communicating with is obtained.

In the embodiment shown in FIG. 6, the bimorph electrostrictive element 22
Since the amount of displacement changes depending on the drive voltage as shown in FIG.
When the switching spool 12 is placed in the left switching position by the hydraulic pressure of the spool hydraulic pressure chamber 14 obtained in the closed state of , and then the first drive voltage is applied to the bimorph electrostrictive element 22, switching to the right side as shown in the figure can be performed, for example. The switching spool is moved to the neutral position in balance with the pilot hydraulic pressure in the spool hydraulic pressure chamber 14 obtained by the throttling action at the opening of the nozzle 14 with the spring 16. and a second drive voltage higher than the first drive voltage.
The switching state to the right as shown in the figure may be obtained by applying a driving voltage of .

FIG. 7 is a sectional view showing another embodiment of the present invention in which a pressure balanced needle valve is actuated by a bimorph electrostrictive element to switch the spool.

First, to explain the configuration, switching spools 1 and 2 having lands 12a, 12b, 1-2c, and 2d are slidably provided inside the valve body 10, and springs 16a and 16b are mounted on both sides of the switching spool 120. A spool hydraulic chamber 1.3.14 is formed with a spool hydraulic chamber 13.
, 14 form a discharge flow path leading to the tank line T by means of communication passages 19 and 20 via pressure balance type side valves 34 and 35.

Each of the pressure balanced needle valves 34,35 has a wire 3
6.37, the bimorph electrostrictive element 21.22 is connected to the tip of the bimorph electrostrictive element 21.22 which is cantilever-supported by the valve body 10 at the fixed portion 23.24.

The operation of the embodiment shown in FIG. 7 is as follows: First, when no driving voltage is applied to the bimorph electrostrictive elements 21 and 22, the discharge flow path of the spool hydraulic chambers 13 and 14 to the tank line T is a pressure-balanced needle valve. It is closed by 34°35.

In the closed state of the pressure-balanced needle valve, for example, as shown in FIG. acts on both sides of the needle valve spool as shown by the arrows, so even if the storage part of the bimorph electrostrictive element 21 is connected to the tank line T, the pressure balance causes the needle valve spool to can be moved with small force.

Next, for example, if a driving voltage is applied to the left bimorph electrostrictive element 21 as shown in FIG. The spool is pulled out and the hydraulic pressure in the spool hydraulic pressure chamber 13 is discharged to the tank line T side. At this time, as shown in FIG. 8, since the needle valve spool is of a pressure balance type, even if the force due to the displacement of the bimorph electrostrictive element 21 is small, the side valve spool can be easily moved to open the discharge flow path. can be formed.

Of course, when the pressure balanced needle valve 34 is operated by the bimorph electrostrictive element 21 as shown in FIG. 9, the pilot hydraulic pressure in the spool hydraulic chamber 1-3 as shown in FIG. 7 decreases, and the switching spool 12 moves to the left side. , connect the pump line P to the switching line A, and connect the switching line B to the tank line T.
It becomes a switching state where it communicates with.

It should be noted that the present invention is not limited to the above embodiments, but includes all types of switching valves using conventional electromagnetic solenoids in which the electromagnetic solenoids are replaced with bimorph electrostrictive elements.

(Effects of Example) Next, effects specific to the example will be explained as follows.

First, in the nozzle flapper structure shown in the embodiment of FIG. 4, in addition to the force due to the displacement of the bimorph electrostrictive element, the adsorption force due to the jet from the nozzle is utilized, so the displacement force of the bimorph electrostrictive element is used. Even if the voltage is small, it is possible to reliably close the nozzle from which a high-pressure liquid stream is ejected, and conversely, since the driving force of the bimorph electrostrictive element may be small, the driving voltage for the bimorph electrostrictive element can be reduced.

Next, in the embodiment shown in Fig. 7, a pressure-balanced needle valve operated by a bimorph electrostrictive element is used to switch the spool, so even if the displacement force of the bimorph electrostrictive element is small, the spool can be reliably switched. Since switching can be performed and the driving force of the bimorph electrostrictive element can be small as in the embodiment shown in FIG. 4, the driving voltage can be lowered.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, FIG. 2 is a graph showing the amount of displacement with respect to the driving voltage of the bimorph electrostrictive element used in the embodiment of FIG. 1, and FIG. 4 is an explanatory diagram of another flapper nozzle structure used in the present invention, and FIG. 5 is a sectional view showing the switching state of the embodiment shown in FIG. 6 is a sectional view showing another embodiment of the present invention having a one-sided switching structure, and FIG. 7 is a sectional view showing another embodiment of the present invention using a pressure-balanced needle valve. cross section,
8 and 9 are explanatory diagrams of the operation of the pressure balance type needle valve of FIG. 7, and FIG. 10 is a sectional view showing a conventional example. 10: Valve body 12: Switching spools 12a, 12b, 12c, 12d: Lands 1.3. 1
．． 4. 33 Nispuru hydraulic chamber 15: Throttle 16a, 16b Nispring 1.7, 18, 30: Nozzle 19.20: Communication path 21.22, 28, 29: Bimorph electrostrictive element 23.2
4: Fixed parts 25a, 25b, 26a, 26b: Lead terminal wire 27
: Nozzle flap member 31; Nozzle hole 32: Flat surface 34.35: Pressure balance 36.37: Wire

Claims (4)

[Claims] (1) In an electric switching valve that switches the flow direction of fluid, there is a switching spool supported in a neutral position by the pressure of a spring; and a pilot fluid pressure is supplied to a switching spool formed on one or both spool end faces of the switching spool. a spool hydraulic pressure chamber; a discharge channel for discharging the pilot hydraulic pressure supplied to the spool hydraulic pressure chamber; and a discharge channel that is displaced by application of a driving voltage to open or close the discharge channel and move the switching spool to a switching position. An electric switching valve characterized by comprising a bimorph electrostrictive element to be moved. (2) The electric switching valve according to claim 1, wherein the discharge passage of the spool hydraulic pressure chamber has a nozzle structure, and the bimorph electrostrictive element has a nozzle flapper structure for opening and closing the nozzle. . (3) The electric switching valve according to claim 2, characterized in that the diameter of the flat surface of the nozzle opening facing the nozzle flapper made of the bimorph electrostrictive element is at least twice the diameter of the nozzle hole. . (4) The electric switching valve according to claim 1, wherein a pressure balanced needle valve driven by the bimorph electrostrictive element is provided in the discharge flow path of the spool hydraulic pressure chamber.