JPS60211176A - Valve - Google Patents

Abstract

PURPOSE:To accomplish fine and high-speed control and to restrain the generation of noise by providing mechanism for magnifying the axial displacement of a laminated piezo-electric element caused by applied electric field and a plunger coupled to the magnifying mechanism. CONSTITUTION:As a piezo-electric ceramic plate 20 is polariazed in direction of thickness, on applying voltage thereto, the piezo-electric ceramic plate is extended in proportion to voltage in the direction of thickness. The base of the laminated piezo-electric element is adhered to a housing 26, and the upper surface thereof is connected to the upper surface piston portion of a hydraulic pump 22. A plunger 23 is coupled to the lower surface piston portion of the hydraulic pump 22. As the ratio of the sectional area of the upper surface piston portion of the hydraulic pump to that of the lower surface piston portion thereof is 25:1, the displacement of the laminated piezo-electric element 20 can be magnified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve used for controlling the flow rate of water, air, gas, oil, steam, etc.

(Prior Art) As this type of pulp, electromagnetic pulp is well known and is in practical use.

FIG. 1 is a schematic diagram for explaining the structure of electromagnetic pulp. In FIG. 1, reference numeral 1 denotes a main body having a lower fluid inlet and an outlet 8, and when not in operation, a plunge prevents fluid from flowing into the pulp. Reference numeral 4 denotes an iron core, and when current is applied to the winding 5, the iron core 4 acts as the plunger 2 due to the weight of the plunger 2 and the spring force of the plunger 2 when the current to the magnetic winding 5 is stopped.
Press it all the way down the bottom of the door, and the space between the entrance and exit is again adjusted to an appropriate number.

6 is a housing, which is essential for storing the above-mentioned parts and maintaining mechanical strength.

According to the operating principle described above, the longer the time for the current to flow through the first winding 5, the greater the flow rate flowing from the input lower to the outlet 8.

(Problems with the Prior Art) A problem with the electromagnetic pulp having the above-mentioned configuration is the noise problem caused by leakage magnetic flux generated when current flows into the winding WA5 and which affects other devices.

In recent years, with the advancement and miniaturization of digital circuits and microcomputers, it has become inevitable to control electromagnetic valves using the above-mentioned electronic devices. Digital circuits are controlled by small-level signals at the TTL level, and there are many components such as relays that have inductance components in large-scale integrated boards, so leakage magnetic flux combines with the inductance components and becomes a noise source. This may cause malfunction. Therefore, in order to solve the problem of magnetic flux leakage from the electromagnetic valve, it is necessary to take measures such as electromagnetic shielding.

Another major problem is that, as can be seen from the operating principle of the electromagnetic valve described above, fine control of the flow rate cannot be performed. That is, since the moving distance of the plunger is fixed, the only way to reduce the flow rate is to reduce the on/off interval of the current in the coil or the current value. In addition, the operating time of plunger springs is too slow to meet the speeds required in the digital age, and when performing on/off operations at high speeds, plunger springs with specially designed springs with solved frequency characteristics are required. In addition, even if the above current value is controlled, it is difficult to control the plunger accurately due to changes in the current value.Also, due to the above problems with the spring, etc.
Electromagnetic valves are considered unsuitable as future flow valves that will require fine, high-speed performance.

That is, as described above, with the development of digital circuits and microcombinators, finer and faster control of flow rate is required in order to increase system operating speed and economy.

On the other hand, there is also an idea to use piezoelectric elements in all of the above-mentioned plunger opening/closing controls, thereby solving all of the drawbacks of the above-mentioned electromagnetic valves.

FIG. 4 is a schematic diagram for explaining the basic properties of a piezoelectric element. Polarized piezoelectric element 9 (arrows indicate polarization direction).

) are provided at both ends of the electrode 10.10't-, and are connected to a power source Bl via a switch Slf.

When the switch 81f is closed and an electric field is applied as shown in the figure, the piezoelectric element 9 expands in the direction of the electric field, and when the switch Sli is turned off, it contracts to its original size and follows changes in the electric field at a speed of several tens of n5ec. However, a drawback of piezoelectric elements is that their expansion and contraction ratio is small. Since the expansion/contraction rate of piezoelectric materials is approximately proportional to the electric field strength, if the thickness of the piezoelectric element is increased to increase the amount of expansion/contraction, a high-voltage power source is required. To give a specific example, the amount of elongation is 2 to 3 μm when a voltage of 600 V is applied to a piezoelectric element with a thickness of 1 ml'r1. In principle, it is possible to increase the amount of expansion and contraction by increasing the applied voltage, but this is not preferable in terms of fully operating the valve at a higher speed, and is also not preferable in terms of safety because it uses a high voltage power source.

That is, as can be seen from the operating principle of the piezoelectric element described above, in order to expand and contract the piezoelectric element at a higher speed, the switch Ss
It is necessary to operate at high speed, and transistors are used. Therefore, in order to increase the voltage applied to the piezoelectric element, it is necessary to develop a transistor that can operate at high voltage and high speed in an isometric manner.

3(a) and 3(tb) are schematic diagrams for explaining the structure of a power alloy junction transistor, in which 11 is a base, 12 is an emitter, 13 is a collector, and 14 is a semiconductor substrate. As can be seen from the figure, the area of the emitter and collector is made as large as possible to prevent the current density from becoming excessive. As the switching speed increases, current flows only near the electrode surface due to the skin effect, so it is necessary to further increase the surface area of the electrode. Therefore, the higher the speed and the higher the voltage resistance, the larger the surface area of the semiconductor and electrode, and the lower the yield and the higher the cost compared to the transistors with lower voltage resistance.

There is also a method of dividing and switching a high voltage using a plurality of low-voltage transistors, but this requires adjustment time to solve all the problems of delay and balance of each transistor. For the above reasons, increasing the voltage applied to the piezoelectric element to increase the amount of expansion and contraction is not desirable in order to operate the valve at higher speeds, and is a major obstacle in making the valve more affordable and smaller. ing.

As explained above, conventional valves, whether electromagnetic valves or piezoelectric element valves, are required as electronics progresses in recent years. There is a problem that requirements such as high speed, noise resistance, high performance, and economic efficiency cannot be satisfied.

(Object of the invention) The object of the invention is to solve the above problems,
It is an object of the present invention to provide a valve that can be controlled more finely and at high speed and operates stably without generating noise.

(Structure of the Invention) The valve of the present invention includes a laminated piezoelectric element formed by laminating and integrating thin plate-like piezoelectric elements, a displacement amplifying mechanism that magnifies the displacement of the laminated piezoelectric element in the axial direction due to an applied electric field, and a plunger coupled to an expansion mechanism.

(Detailed Description of IN Formation) The present invention solves the drawbacks of the prior art by adopting the above configuration. In other words, instead of the conventional piezoelectric element being a laminated layer of thin plate piezoelectric elements using an adhesive, thin plate piezoelectric elements can be laminated without using an adhesive by applying the technology of laminated ceramic capacitors. An integrated multilayer piezoelectric element (IEICE Ultrasound Study Group Material US83-8, pp. 55-59, May 1983) and a displacement magnification mechanism full plunger that magnifies the displacement of this multilayer piezoelectric element. By connecting the laminated layers to the piezoelectric element, the high performance of the piezoelectric element and the expansion of displacement by the displacement magnification mechanism make it possible to drive the laminated layers at low voltage and at high speed.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 4 is a schematic diagram for explaining the configuration of one embodiment of the present invention, and FIG. 5 is a schematic diagram for explaining the laminated piezoelectric element used in this embodiment.

This embodiment includes a laminated piezoelectric element 20 formed by integrally laminating a piezoelectric ceramic plate 20' with gold as a thin piezoelectric element, and a displacement amplifying mechanism that magnifies the displacement of the laminated piezoelectric element 20 in the axial direction due to an applied electric field. The hydraulic pump 22 includes a hydraulic pump 22 and a plunger 23 connected to the hydraulic pump 22.

In FIG. 4, 21 is the main body, 24°, 24' and 25 are the external and internal electrodes of the laminated piezoelectric element, 26 is the housing, 27 is the bolt, and 28 is the inlet percentage.
29 is an exit, and the lamination is connected to the external electrodes 24 and 2 of the piezoelectric element 20.
4' is connected to a variable power source E2 via a switch 82f.

Referring to FIG. 5, the laminated piezoelectric element 2o.

A large number of piezoelectric ceramic plates 20' are laminated and integrated as one ceramic block, and a large number of internal electrode layers 25 are embedded inside the ceramic in a layered manner.
It has a shape that is exposed at the end face of the element. Every other exposed internal electrode 25 is covered with an insulator 30, and the external electrodes 24, 24' are applied from above, so that the internal electrode layers 25 are electrically parallel to each other. It will be connected. Furthermore, since the piezoelectric ceramic plate 20' is polarized in the thickness direction, the external electrode element 20 has a diameter of 3Q mm and a length of 53 mm, and the internal electrode spacing is 50 mm.
A μm type is used, and the power supply E2 is 100V.
When a voltage of 108 is applied, the upper surface is connected to the piston portion on the upper surface of the hydraulic pump 22. Hydraulic pump 22 is fixed to housing 26. A plunger 23 is connected to the piston portion on the lower surface of the hydraulic pump 22, and the displacement can be expanded to 2700 μm, which is 25 times the displacement of the piezoelectric element 20. In a conventional electromagnetic valve, the amount of displacement is about 800 μm, so the amount of displacement can be more than three times larger.

It is communicated effectively. Further, the power source E2 and the switch S2 are actually controlled by a converter.

As a result of an operation test using this example, the power supply voltage lo
OV, the operating speed was five times faster than conventional electromagnetic valves, it could be controlled finely, and there was no noise at all.

(Effects of the Invention) As described in detail above, the pulp of the present invention (1) has no noise problem because of the structure in which small, high-performance laminated piezoelectric elements are entirely used to control the position of the plunger.

(2) Fine and high-speed control of flow rate is possible.

(3) It is possible to drive at a low voltage, and it is possible to simplify and downsize the device and drive circuit.

It has the following effects. Therefore, economical 9 functional.

You can get all the valves with excellent reliability.

[Brief explanation of drawings]

Figure 1 is a schematic diagram to explain the production of an example of conventional electromagnetic pulp, Figure 2 is a schematic diagram to explain the basic properties of a piezoelectric element, and Figure 3 is a metal-containing type for electric power. FIG. 4 is a schematic diagram for fully explaining the structure of an embodiment of the present invention, and FIG. 5 is a schematic diagram for explaining the structure of an embodiment of the present invention. It is a schematic diagram. 1...Main body, 2...Plunger, 3.
... Plunger, 4... Iron core, 5.
...Winding, 6...Housing, 7...
...Inlet, 8...Outlet, 9...Piezoelectric element, 10.10'... Electrode, 11.11'.
...Base, 12.12'...Emitter, 13.13'...Collector, 14...
J semiconductor substrate, 20... laminated wall piezoelectric element, 20
'...... Viewing envelope Rummy, 7 boards, 21...
Main body, 22...Hydraulic pump, 23...
Plunger, 24, 24'...External electrode, 2
5...Internal electrode, 26...Housing, 27...Volt, 28...Inlet, 2
9...Exit, 30...Insulator. El, E2...Power supply, 81.82...
switch. Agent Patent Attorney Susumu Uchihara (゛) ・ -1〉'

Claims (1)

[Claims] A laminated piezoelectric element formed by integrating all laminated layers of thin plate-like piezoelectric elements, a displacement amplifying mechanism that fully expands the displacement of the laminated layer in the axial direction due to an electric field applied to the piezoelectric element, and a plunger connected to the displacement amplifying mechanism. A valve featuring: