JPH0762502B2 - Control valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control valve, and more particularly to a highly accurate control valve using a ceramic element and excellent in responsiveness.

[Conventional technology]

It has been conventionally known that a large number of ceramic elements such as PZT are stacked and supplied with high voltage power to expand and contract, and the expansion and contraction generate mechanical force to perform various mechanical controls. There is.

A mechanical device using such a ceramic element is effectively controlled by an electric signal with good responsiveness and a large mechanical operating force can be obtained, so various mechanical applications are considered. To be

As an example, a laminate of multiple piezoelectric plates that can be displaced or deformed in the flow rate adjustment direction by applying a voltage is provided, and the laminate expands and contracts in response to the application of voltage to displace the valve element Japanese Patent Laid-Open No. 60-175881 discloses a control valve for controlling a small amount with a high-speed response.

[Problems to be solved by the invention]

However, in a control valve using such a ceramic element, hysteresis is generated between the applied voltage and the displacement of the ceramic element, and the applied voltage of the ceramic element with respect to the applied voltage depends on the operating conditions such as temperature. Since the displacement amount is different and further changes over time,
There is a problem that the flow rate control or the pressure control cannot be performed with high accuracy.

The present invention has been made in view of the above problems, and detects a mechanical actuating force generated corresponding to a displacement amount of a ceramic element group that expands and contracts in response to application of a voltage, It is an object of the present invention to provide a control valve that performs highly accurate pressure control or flow rate control by increasing or decreasing the applied voltage based on the dynamic operating force.

[Means for solving problems]

In order to solve the above problems, the present invention takes the following technical means.

The control valve of the present invention is formed by laminating a plurality of plate-shaped ceramic elements with electrode plates interposed therebetween, and a ceramic element group that expands and contracts according to the application of a voltage, and a ceramic element of this ceramic element group. A detection ceramic element that is integrally laminated with the ceramic element group and detects a mechanical actuating force generated in response to expansion and contraction of the ceramic element group; It is equipped with a reciprocating member that can be changed and a control circuit in which a target value of the mechanical actuating force determined in accordance with the applied voltage applied to the ceramic element group is preset, and it corresponds to expansion and contraction of the ceramic element group. The mechanical actuating force that is actually generated is detected by the ceramic element for detection, and in the control circuit, this detected value is compared with the target value to print the ceramic element group. Increasing or decreasing the applied voltage.

[Action]

The present invention having the above structure operates as follows. That is, when a voltage is applied to each ceramic element of the ceramic element group, distortion is generated in each ceramic element according to the state of the applied voltage, and the ceramic element group expands and contracts.

The reciprocating member reciprocates in response to expansion and contraction of the ceramic element group, changes the passage area of the fluid passage through which the fluid flows, and controls the flow rate or the pressure.

Here, when the reciprocating member reciprocates due to expansion and contraction of the ceramic element group, a mechanical actuating force determined by the position of the reciprocating member is generated. That is, a mechanical actuating force is generated due to the amount of displacement of the ceramic element group. This mechanical actuation force is detected by the detecting ceramic element that is integrally laminated with the ceramic element, and the control circuit compares this detected value with the target value to determine the applied voltage applied to the ceramic element group. Is increased or decreased to match the detected value with the target value.

Therefore, even if a hysteresis occurs between the applied voltage and the displacement amount of the ceramic element group, or the displacement amount of the ceramic element group changes depending on the usage conditions such as temperature, or even if it changes over time. , By increasing or decreasing the applied voltage applied to the ceramic element group as described above, the mechanical operating force generated corresponding to the displacement amount of the ceramic element group can always be controlled with stable accuracy, It is possible to perform pressure control or flow rate control with high accuracy.

〔Example〕

Next, a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a vertical sectional view showing the structure of this embodiment.

In FIG. 1, a casing 1 forming the outer shape of the control valve of this embodiment is composed of a first casing 1a, a second casing 1b, and a fixing member 1c.

The first casing 1a has a cylindrical shape, and the first casing 1a
A piston 32 is slidably inserted therein. The piston 32 has a cylindrical shape with a bottom having a bottom surface portion 32a, and slides in the first casing 1a under the force of expansion and contraction of a piezoelectric element group 20 described later.

The piezoelectric element group 20 and the detection piezoelectric element 30 are arranged between the bottom surface portion 32a of the piston 32 and the disc-shaped fixing member 1c fixed to the first casing 1a.

The piezoelectric element group 20 is a ceramic element group of the present embodiment in which a large number of disc-shaped piezoelectric elements are stacked with the electrode plate 21 interposed therebetween, and the piezoelectric element group 20 is connected to the control circuit 37 via the lead wire 25 to form a high voltage. A voltage signal is applied. Distortion occurs in each piezoelectric element plate according to the state of the applied high voltage signal, and the piezoelectric element group 20
The length in the stacking direction is controlled to expand and contract.

On the surface of the piezoelectric element group 20 on the piston 32 side, the detecting piezoelectric element 30 which is the detecting ceramic element of this embodiment for detecting the mechanical actuating force due to the displacement amount of the piezoelectric element group 20 is an insulating plate such as a ceramic. It is laminated integrally through 31. And
The detection signal from the detection piezoelectric element 30 is supplied to the control circuit 37 via the lead wire 35.

Here, the piezoelectric element group 20, the insulating plate 31, and the detection piezoelectric element 30.
Are integrally fixed and laminated, and one side surface of this integrated structure is fixedly set to the fixing member 1c.

The pressure chamber 10 includes a bottom surface portion 32a of the piston 32 and the first casing 1
It is formed by the inner peripheral surface of a and the end surface of the needle end 2c described later, and the working fluid is stored in this pressure chamber 10. The volume of the pressure chamber 10 changes as the piston 32 slides in the first casing 1a. Also, the pressure chamber 10
A spring 36 is arranged inside and urges the piston 32 toward the fixed member 1c. An O-ring 12 is provided on the inner peripheral surface of the one casing 1, which is the sliding surface between the first casing 1a and the piston 32, in order to prevent leakage of the working fluid in the pressure chamber 10.

The second casing 1b is fixedly connected to the first casing 1a, and a sliding chamber 4 is formed in the second casing 1b. The sliding chamber 4 is a communication hole formed in the first casing 1a. It communicates with the pressure chamber 10 via 5. Also, the sliding chamber 4
Communicates with the introduction passage 6 through the introduction hole 8 and communicates with the extraction passage 7 through the extraction hole 9. The introduction passage 6 communicates with a hydraulic pressure generation source such as a hydraulic pump, and the fluid is introduced into the sliding chamber 4 through the introduction passage 6.

A needle 2, which is a reciprocating member of this embodiment, is slidably fitted in the sliding chamber 4, and the needle 2 has a valve portion.
2a, a disk portion 2b, and an end portion 2c.

The end 2c of the needle 2 is slidably fitted in the communication hole 5 of the first casing 1a, and slides by receiving the hydraulic pressure of the working liquid in the pressure chamber 10. Here, since the pressure receiving area received by the end portion 2c of the needle 2 is smaller than the pressure receiving area received by the piston 32 in the pressure chamber 10, the displacement amount of the needle 2 is larger than the displacement amount of the piston 32. An O-ring 11 is provided on the inner peripheral surface of the communication hole in which the end 2c of the needle 2 slides to prevent the working fluid in the pressure chamber 10 from leaking.

The disk portion 2b of the needle 2 is slidable in the sliding chamber 4, and the disk portion 2b is biased toward the pressure chamber 10 by the spring 3 arranged in the sliding chamber 4. .

The valve portion 2a of the needle 2 has a cylindrical shape, and the tip portion has a conical shape. The diameter of the valve portion 2a is larger than the inner diameter of the introduction hole 6, and when the needle slides in the sliding chamber 4 to the left in the figure, the valve portion 2a reduces the passage area of the introduction hole 8 and the introduction passage. The hydraulic pressure on the 6 side increases. That is, the reciprocating motion of the needle 2 controls the hydraulic pressure on the upstream side.

Here, the hydraulic pressure received by the needle 2 from the fluid flowing in through the introduction passage 6 and the introduction hole 8 is F, and the end portion 2c of the needle 2 is
Let A _{1 be} the cross-sectional area of the piston and A _{2 be} the cross-sectional area of the piston 32, the fluid pressure in the pressure chamber 10 is F / A ₁ , and the piston 32 and the piezoelectric element 30 for detection are the load F · A ₂ / A _1. Receive. That is, the load applied to the detection piezoelectric element 30 is uniquely determined by the hydraulic pressure F applied to the needle 2. Therefore, when the needle 2 slides due to the expansion and contraction of the piezoelectric element group 20, the detection piezoelectric element 30
The mechanical actuating force applied to the piezoelectric element group 20 by the expansion and contraction of the piezoelectric element group 20 is uniquely determined by the hydraulic pressure received by the needle 2 from the liquid. Also, expansion and contraction of the piezoelectric element group 20 is basically
Since it is determined by the state of the applied voltage applied to 20, the target value of the mechanical actuating force generated corresponding to the applied voltage can be set.

The control circuit 37 is preset with a target value determined in accordance with the applied voltage applied to the piezoelectric element 20 based on the above logic.

The present embodiment having the above configuration operates as follows.

When no voltage is applied to the piezoelectric element group 20, the needle 2 is urged by the spring 3 toward the pressure chamber 10 as shown in FIG. 1, and the introduction passage 6 and the passage hole are formed. The fluid introduced into the sliding chamber 4 via 8 is led out to the outlet passage 7 via the outlet hole 9.

Next, when a predetermined voltage is applied to the piezoelectric element group 20 via the control circuit 37 to perform the flow rate control, the piezoelectric element group 20 expands in response to the applied voltage. By sliding against the left side in the figure, the volume of the pressure chamber 10 decreases. Therefore, the working fluid in the pressure chamber 10 flows into the communication hole 5, and the end portion 2c of the needle 2 slides in the communication hole 5 leftward in the drawing by receiving this hydraulic pressure. Along with this sliding, the needle 2 slides in the sliding chamber 4 to the left in the drawing. As a result, the valve portion 2a of the needle 2 reduces the passage area of the introduction hole 8, and the hydraulic pressure on the introduction passage 6 side rises in association with the passage area. Since the passage area is determined by the displacement amount of the needle, the hydraulic pressure on the introduction passage 6 side is controlled by the displacement amount of the needle 2.

Here, as the piezoelectric element group 20 expands, the hydraulic pressure that the needle 2 receives from the liquid flowing in through the introduction passage 6 and the introduction hole 8 increases, and the mechanical actuation force is the needle 2 and the pressure chamber 10. It acts on the piezoelectric element 30 for detection through the working fluid and the piston 32 in that order. The mechanical actuation force is detected by the detecting piezoelectric element 30 and sent to the control circuit 37 as an electric signal. In the control circuit 37, the detected value is compared with a preset target value, and when the detected value is larger than the target value, the applied voltage applied to the piezoelectric element group 20 is decreased so that the detected value is the target value. When it is smaller than the value, the applied voltage applied to the piezoelectric element group 20 is increased.

Therefore, a hysteresis is generated between the applied voltage and the displacement amount of the piezoelectric element group 20, or the displacement amount of the piezoelectric element group 20 is changed depending on the usage conditions such as temperature, and further, a change over time occurs. Also, the mechanical actuating force generated corresponding to the displacement amount of the piezoelectric element group 20 by increasing or decreasing the applied voltage to be applied, that is, the load uniquely determined by the hydraulic pressure received by the needle 2 is always It is possible to control with stable accuracy, and thus it is possible to control flow rate or pressure with high accuracy.

Here, as described above, the hydraulic pressure received by the needle 2 is determined by the displacement amount of the needle 2, and the displacement amount of the needle 2 is determined by the displacement amount of the piezoelectric element group 20. The fact that the load forming the operating force can always be controlled with stable accuracy means that the displacement amount of the piezoelectric element group 20 can be controlled with stable accuracy at all times, which enables highly accurate flow rate control or pressure control. .

Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 2 is a vertical sectional view showing the structure of this embodiment.

In FIG. 2, as in the first embodiment, a piston 32, a piezoelectric element group 20, an insulating plate 31, and a detecting piezoelectric element 30 are arranged in a casing 101. The piezoelectric element group 20, the insulating plate 31 and the detection piezoelectric element 30 are fixed and laminated integrally and fixedly set on the fixing member 102. In addition, the piezoelectric element group 2
The zero and the detecting piezoelectric element 30 are connected to a control circuit 37.

The pressure chamber 10 is formed by the bottom surface portion 32a of the piston 32 and the inner peripheral surface of the casing 101, and the working fluid is stored in the pressure chamber 10. Further, the volume of the pressure chamber 10 changes as the piston 32 slides in the casing 1a. Further, a spring 36 is arranged in the pressure chamber 10 and urges the piston 32 toward the fixed member 102 side.

A spool chamber 103 having one end communicating with the pressure chamber 10 is formed in the casing 101, and a ring 104 for preventing leakage is provided on the inner peripheral side of the spool chamber 103.
The spool chamber 103 is in communication with an introduction passage 60 for introducing a fluid into the spool chamber 103, and a first outlet passage 61 and a second outlet passage 62 for leading out the fluid in the spool chamber 103.

A cylindrical spool 50, which is a reciprocating member, is slidably fitted in the spool chamber 103, and the spool 50 is composed of end portions 50a and 50c at both ends and a small diameter portion 50b at the center. . The spool 50 receives the hydraulic pressure of the working fluid in the pressure chamber 10 by the end surface of the end portion 50c and slides in the spool chamber 103. The sliding of the spool 50 controls the flow rate of the fluid introduced from the introduction passage 60 into the spool chamber 103, which is led out from the first outlet passage 61 and the second outlet passage 62.

That is, in the state shown in FIG. 2, the spool
The first outlet passage 61 is closed by a predetermined area by the end portion 50a of 50, and the flow rate discharged from the first outlet passage 61 is limited. However, when the spool 50 slides to the left in the drawing, the first outlet passage 61 is formed.
Is not blocked and the flow rate increases gradually. On the other hand, regarding the second outlet passage 62 as well, in the state shown in FIG. 2, the second outlet passage 62 is not closed and the fluid of the integrated flow rate is led out.
62 is closed by the end 50c of the spool 50, and the flow rate discharged is controlled.

Further, a spring 51 is arranged on the other end side of the spool chamber 103, and the spool 50 is moved to the right in the figure in a state where no voltage is applied to the piezoelectric element group 20 as shown in FIG. Energize.

The present embodiment having the above configuration operates as follows.

In the state where the high voltage is not applied to the piezoelectric element group 20, as shown in FIG. 2, the fluid introduced into the spool chamber 103 from the introduction passage 60 is the first discharge passage 61 and the second discharge passage 61.
A predetermined amount is led out from the lead-out passage 62.

Next, when a high voltage is applied to the piezoelectric element group 20 via a control circuit (not shown), the piezoelectric element group 20 expands. Therefore, the piston 32 slides to the left in the figure against the spring 36, and the volume of the pressure chamber 10 decreases. Therefore, the working fluid in the pressure chamber 10 is introduced to the one end side of the spool chamber 103, and the spool 50 slides in the spool chamber 103 against the biasing force of the spring 51. With this sliding of the spool 50, the spool 50
First lead-out passage 6 that was blocked by a predetermined area by the end 50a of the
1 is no longer blocked, and the flow rate of the fluid discharged from the first discharge passage 61 gradually increases. On the contrary, the second outlet passage 62
Is gradually closed by the end 50c of the spool 50, and the second
The flow rate of the fluid discharged from the discharge passage 62 decreases.

Here, as the spool 50 slides, the end 50 of the spool 50
The urging force of the spring 51 acting on the end face of a increases, and this mechanical actuating force acts on the detecting piezoelectric element through the spool 50, the working fluid in the pressure chamber 10 and the piston 32 in this order. The following operations are the same as in the above embodiment.

As described above, according to the present embodiment, the flow rate of the fluid introduced into the spool chamber 103 that is discharged from the first discharge passage 61 and the flow rate that is discharged from the second discharge passage 62 can be controlled at once. . Also in this embodiment, similarly to the above-described embodiment, the detection piezoelectric element 30 for detecting the mechanical actuating force generated corresponding to the expansion and contraction of the piezoelectric element group 20 is integrally laminated with the piezoelectric element group 20. , The mechanical actuating force generated corresponding to the displacement of the piezoelectric element group 20, that is, the load uniquely determined by the urging force of the spring 51, can always be controlled with stable accuracy, and thus the flow rate can be controlled with high accuracy. You can

Here, as described above, the biasing force of the spring 51 is determined by the displacement amount of the spool 50, and
The displacement amount of is determined by the displacement amount of the piezoelectric element group 20, and the fact that the load forming the mechanical actuating force can be controlled always with stable accuracy means that the displacement amount of the piezoelectric element group 20 is always stable with accuracy. Therefore, the flow rate can be controlled with high accuracy.

Although the piezoelectric element is used as the detection ceramic element in the two embodiments, an electrostrictive element may be used instead of the piezoelectric element. Since the electrostrictive element has better load-charge characteristics than the piezoelectric element, more accurate control becomes possible.

Further, in the above-mentioned two embodiments, the detection piezoelectric element 30 is set corresponding to one surface portion of the piezoelectric element group 20 in which the detection piezoelectric element 30 is stacked.
The same effect can be obtained by interposing between the piezoelectric element and the piezoelectric element.

Furthermore, in the above two examples, the piezoelectric element was used as the ceramic element group, but the same effect can be obtained by using the electrostrictive element.

〔The invention's effect〕

As described above, according to the present invention, the amount of displacement of the ceramic element group can always be controlled with stable accuracy by increasing or decreasing the applied voltage applied to the ceramic element group in the control circuit. Therefore, the reciprocating member can be reciprocated with accurate accuracy, and highly accurate flow rate control or pressure control can be performed.

Further, since the detecting ceramic element is integrally laminated with the ceramic element group, the physical size is not increased at all.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the structure of the first embodiment of the present invention. FIG. 2 is a vertical sectional view showing the structure of the second embodiment of the present invention. 2 …… Needle (reciprocating member), 6 …… Introduction passage, 7 …… Outlet passage, 20 …… Piezoelectric element group (ceramic element group), 21 ……
Electrode plate, 30 ... Piezoelectric element for detection (ceramic element for detection), 31 ... Insulation plate, 37 ... Control circuit, 50 ... Spool (reciprocating member).

Claims (2)

[Claims] 1. A ceramic element group, which is formed by laminating a plurality of plate-shaped ceramic elements between each other with an electrode plate interposed therebetween and expands and contracts in response to the application of a voltage, and a ceramic element of the ceramic element group. A detection ceramic element that is laminated on the ceramic element group and detects a mechanical actuating force generated in response to expansion and contraction of the ceramic element group; And a control circuit in which a target value of a mechanical actuating force determined corresponding to an applied voltage applied to the ceramic element group is preset, and Correspondingly, the mechanical actuating force actually generated is detected by the detecting ceramic element, and the detected value is compared with the target value in the control circuit. A control valve for increasing or decreasing an applied voltage that ignites the ceramic element group. 2. The control valve according to claim 1, wherein the ceramic element group and the detection ceramic element are integrally laminated with an insulating plate interposed.