JPS62141381A - Piezoelectric driving type valve - Google Patents

Abstract

PURPOSE:To facilitate the setting of the initial flow rate and the fine adjustment of the flow rate in use by nipping a valve piece consisting of a piezoelectric element between a valve body and a housing and installing an adjusting mechanism for the pressing force for the valve piece. CONSTITUTION:When a dc voltage is applied onto a piezoelectric ceramic body 13, said piezoelectric element is bent into convex or recessed form from the outer peripheral part to the center part. A valve piece 8 is set or separated from a valve seat 7 by the bending movement of the piezoelectric element, i.e., valve piece 8, and the flow rate of fluid controlled. Further, a load adjusting screw 9 is advanced or retreated by twisting the load adjusting screw 9 screwed onto a housing 2, and the pressing force for the valve piece 8 is adjusted to set a desired initial flow rate.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a valve (hereinafter referred to as a piezoelectric driven type) that uses a piezoelectric body as a driving source to adjust the position of a valve body and control the flow rate of fluid. The present invention relates to improvements in the power of a piezoelectrically driven valve, which is suitable for precisely controlling fluids in a relatively small flow rate range.

[Conventional technology]

Conventionally, valves used to handle fluids in a relatively small flow rate range of several cc to several hundred cc per minute include, for example, solenoid valves that utilize twist/id, or thermal valves that utilize thermal expansion of metal. (U, S, P 3v6
50, 505), etc. are known.

However, with solenoid valves, it is relatively difficult to accurately control minute flow rates, and they tend to generate heat due to iron loss and resistance loss caused by solenoid excitation.
Since it has many structural parts and is relatively complex, it has disadvantages such as poor productivity and maintainability. In addition, thermal valves have the advantage of being able to control the flow rate with relatively high precision and can be made into small control valves, but they have problems in terms of response time because they use the thermal expansion of metal to drive the valves. was there.

Recently, in order to solve the problems of the conventional technology,
Piezoelectrically driven valves are beginning to be proposed.

That is, for example, a method in which a cylindrical piezoelectric body is inserted into a flow path and the flow rate is controlled by increasing or decreasing the cross-sectional area of the flow path caused by changes in the axial direction of the piezoelectric body (Japanese Patent Application Laid-open No. 55-149470), polymer piezoelectric materials. There is a method (Japanese Unexamined Patent Publication No. 57-29801) in which the periphery of a plurality of bimorph type piezoelectric laminates made of film is fixed and a seven-ram valve connected to each other is closed by displacement of the piezoelectric laminates.

[Problems that the invention attempts to solve]

However, the device using the cylindrical piezoelectric body utilizes the displacement of the piezoelectric body in the axial direction, and since the amount of displacement is on the order of μm or less, the adjustment margin for the flow rate is extremely small. In addition, those using the above-mentioned polymeric piezoelectric material film,
Since the displacement of the central part of the element is used, the amount of displacement is usually large, around 100μ, but in order to obtain the desired driving force, a large number of piezoelectric bodies must be used, so the structure is ! ! This results in poor reliability and responsiveness. For this reason, there has been a desire for a small flow rate control valve that can accurately control fluid in a minute flow rate range.

In view of the above two requests, this invention provides a small piezoelectrically driven valve that is easy to set the initial flow rate, is easy to adjust the flow rate during use, generates little heat, and has good responsiveness. The purpose is to

[Means for solving problems]

In order to achieve the above object, the present invention drives a valve body using the displacement of a piezoelectric body that occurs in response to an applied voltage,
In a piezoelectrically driven valve that controls the flow rate of fluid by seating or separating the valve body from the valve seat, a piezoelectric element is used between the valve body and the housing, in which a piezoelectric ceramic body is fixed to one surface of a thin elastic plate. A valve that is equipped with a valve body consisting of a valve body, has a valve chamber that communicates with one flow path provided in the valve body, and has a valve hole that communicates with the other flow path provided in the valve body within the valve chamber. The present invention is characterized in that a seat is provided in a protruding manner to face the valve body, and an adjustment mechanism is attached to the housing, which can freely adjust the application and removal of a pressing force to the valve body.

FIG. 1 is a sectional view showing an example of the basic configuration of a piezoelectrically driven valve according to the present invention.

In FIG. 1, reference numeral 1 denotes a valve body, which is secured to a housing 2 by known coupling means such as bolts (not shown), and a valve chamber 11 is formed between the valve body 1 and the housing 2.

A valve seat 7 having a valve hole 3 protrudes from the valve body 1 into the valve chamber 11. Further, a valve body 8 configured as described below is sandwiched between the valve body 1 and the housing 2 via an O-ring 17. Furthermore, the housing 2 is provided with a load adjusting screw 9 that moves forward and backward in the direction of the valve body 8 via a screw.
A spring 10 is screwed onto the spring 10 and elastically presses the valve body 8.
(In the example shown in FIG. 1, a spring 10 is installed in the load + g adjustment screw 9, and the spring 10 is configured to press the valve body 8 via the ball 18). The valve body 1 is provided with a passage 4 communicating with the valve hole 3 and a passage 5 communicating with the valve chamber 11 via a passage 6.

FIG. 2 is a perspective view showing an example of the construction of the valve body 8 in the piezoelectrically driven valve of the present invention having the above structure.

Basically, the valve body in the present invention has a piezoelectric ceramic body mounted on one side of a diaphragm plate 12 as shown in Fig. MS1.
In this example, an elastic body 14 is attached to the surface of the diaphragm plate 12 opposite to the surface to which the piezoelectric ceramic body is fixed.
It is made by fixing. Further, FIG. 3 is a perspective view of a main part showing an example of a valve seat in the present invention, and a plurality of flow rates 111! % groove 16
is formed. However, this groove 16 is basically not necessary.

Note that the piezoelectric element in the present invention is not necessarily limited to a piezoelectric unimorph, and a piezoelectric element such as a so-called piezoelectric bimorph in which a piezoelectric ceramic body is fixed to both surfaces of a diaphragm plate may be used.

[For production]

The piezoelectrically driven valve of the present invention having the second structure operates as follows. When a DC voltage is applied to the piezoelectric ceramic body 13, the piezoelectric element bends into a convex or gate shape from the outer periphery to the center. In the present invention, since the valve body 8 is formed from the piezoelectric element itself, the bending movement of the piezoelectric element, that is, the valve body 8 causes the valve body to sit on or away from the valve seat 7, thereby controlling the flow rate of the fluid. do. At this time, if the valve seat 7 has a flow rate adjustment groove 16 shaped like F& and the elastic body 14 is fixed to the valve body 8, the opening area of the flow rate adjustment groove 16 will change depending on the degree of deformation of the elastic body 14. , it becomes possible to more finely control the flow rate of the fluid flowing through the groove 1G.

That is, in the present invention, the bending motion of the piezoelectric element that occurs when a DC voltage is applied to the piezoelectric element is used to drive the valve body, and the opening area of the inlet and outlet from the valve body to the valve chamber is reduced. The flow rate is controlled by changing the amount.

Further, in the present invention, the load adjustment screw 9 screwed onto the housing 2 is moved forward and backward by twisting it, and the pressing force against the valve body 8 is adjusted via the spring 10 attached to the load adjustment screw 9. Therefore, the desired initial flow rate can be set.

In the present invention, a voltage having a predetermined frequency is generated by a DC power supply, an oscillator, etc., and this voltage is applied to the piezoelectric element directly or via an amplifier. By adjusting the magnitude of this applied voltage, the amount of bending of the piezoelectric element can be adjusted, and by adjusting the period during the pulse of the applied voltage to 11, the time during which the piezoelectric element is bent can be 'I! 4, and the driving time of the valve body can be adjusted.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on examples.

(Example 1) A brass diaphragm plate 12 with a diameter of 161I1m and a thickness of 0.11Ilffl has a diameter of 12IIIL11.
A valve body 8 was obtained using a unimorph type piezoelectric element to which a PZT-based piezoelectric ceramic body 13 having a thickness of 0.27 mm was bonded.

The peripheral portion of the diaphragm plate (that is, the diaphragm of the piezoelectric element) 12 of this valve body 8 is sandwiched between the valve body 1 made of stainless steel and the housing 2 via an O-ring 17, and the first
A piezoelectrically driven butt t having the structure shown in the figure was manufactured.

In addition, according to the present invention, the diaphragm plate 12 is not necessarily held between the valve body 1 and the housing 2.
Although it is not necessary to insert an O-ring on either side of the diaphragm plate 12,
This is preferable because the degree of sealing of the valve chamber 11 can be improved.

Next, the force for pressing the valve body 8 against the valve body abutting portion 15 of the valve seat 7 is adjusted to 111N using the load adjustment screw 9 via the spring 10, and the valve body 8 is adjusted to 111N when no voltage is applied to the piezoelectric element. It was made to come into close contact with the valve body abutting portion 15. Therefore, when no voltage is applied to the piezoelectric atoms, the flow of fluid such as gas is blocked.

FIG. 4 shows the correlation between the applied voltage and the amount of displacement of the piezoelectric element, that is, the valve body 8. As the applied voltage increases, the amount of displacement also increases, indicating that the amount of displacement of the valve body 8 can be adjusted by changing the applied voltage. The piezoelectric ceramic body 1 has a different amount of displacement when the applied voltage increases and decreases.
This is due to the hysteresis of No. 3, and can be improved by adjusting the amount of displacement and flow rate back to the applied voltage.

As described above, the valve body 8 made of a piezoelectric element is displaced and moved away from or close to the valve body abutting portion 15 of the valve seat 7, thereby adjusting the area of the flow path.

FIG. 5 shows the correlation between the magnitude of the voltage applied to the piezoelectric element and the gas flow rate, and shows that the gas flow rate can be controlled by the applied voltage.

(Embodiment 2) FIG. 6 is a diagram for explaining a second embodiment of the present invention. The structure of the piezoelectrically driven valve was almost the same as in Example 1 (first example).

Load ll! The pressure force for pressing the valve body 8 against the valve body abutting portion 15 of the valve seat 7 is adjusted by the set screw 9 via the spring 10, and the gas flow rate is 7,000 c when no voltage is applied to the piezoelectric element.
Theory 3/n+in.

, ffi Figure 6 shows the correlation between the magnitude of the voltage applied to the piezoelectric element and the gas flow rate under the following conditions.

When no voltage is applied to the piezoelectric element, the distance or pressing force between the valve body 8 and the valve body contact portion 15 is J:
The gas flow rate is 7,000m3/
It is 111 inches. When a voltage is applied to the piezoelectric element, the piezoelectric element is displaced from its initial position, and the gas flow rate is 7,000.
It changed with the applied voltage with cfi3/min as the base point.

(Embodiment 3) FIG. 7 is a sectional view of a piezoelectrically driven valve in a third embodiment.

Its structure is almost the same as that of Example 1.2, but a rubber 14 with a thickness of 0.05 mm is bonded to one side of the diaphragm to form a valve body 8 as shown in FIG. Further, in the valve body abutting portion 15 of the valve seat 7, a radial flow rate 1111 regulating groove 16 is formed.

Load adjustment screw 9: Adjust the force that presses the valve body 8 against the valve body abutting part 15 via the spring 10, and the valve body 8 is set at the valve body abutting part when no voltage is applied to the piezoelectric element. 15, and the flow rate adjustment groove 16 was also completely closed.

When the voltage applied to the piezoelectric element is gradually increased from this state, the piezoelectric element gradually curves and the valve body 8 begins to separate from the bottom of the flow rate adjustment groove 16, and after further separating from the entire groove, the valve body abutting portion 15 It moves away from. Therefore, with the structure of this embodiment, it is possible to control the flow rate by a minute amount.

Figure 8 shows the correlation between the applied voltage and the gas flow rate when performing this minute amount control.
This shows that sufficient control can be achieved even with a gas flow rate of less than n.

As described above in detail, the piezoelectrically driven valve according to the present invention has a valve body composed of a piezoelectric element such as a piezoelectric unimorph having a relatively large amount of displacement, and a load adjusting screw is provided in the housing, and the load adjustment screw is turned. Adjusting the initial flow rate of gas by adjusting the distance between the valve body and the valve body contacting part and the pressing force on the valve body, and controlling the amount of displacement of the valve body from its initial position by externally applied voltage. It is possible to control the flow rate of fluid such as gas.

In addition, by applying a soft material such as rubber to the surface of the valve body contacting part of the valve body, or by forming grooves or other irregularities on the valve body contact part of the valve seat, we can reduce the It is possible to control the flow rate up to a target flow rate.

The shape of the piezoelectric element used in the present invention is not limited to that of the embodiments described above, but may be a piezoelectric unimorph or a piezoelectric bimorph having an equivalent ability as described above.

Further, the material of the soft material adhered to the surface of the valve body is not limited to rubber as in the above embodiment, but may be any other material as long as it is suitable for the irregularities of the valve body abutting portion. The shape of these irregularities is not limited to the grooves as in the above embodiments.

Furthermore, I′p! of the initial position of the valve body! The adjusting mechanism is not limited to a screw as in the above embodiment, but may be any mechanism as long as it can change the position and pressing force of the valve body.

Further, in the above embodiment, the gas flow rate was increased by applying a voltage, but the gas flow rate may be controlled to be decreased by applying a voltage in the opposite direction.

〔Effect of the invention〕

As is clear from the above detailed description, the piezoelectrically driven valve according to the present invention has the following unique effects.

(1) By driving the valve body with a piezoelectric unimorph or piezoelectric bimorph that has a relatively large amount of displacement, the flow rate of fluid can be continuously controlled from a very small amount to a relatively large amount.

(2) The initial flow rate of the fluid when no voltage is applied can be adjusted from outside the valve, making it possible to precisely control the flow rate of the fluid both in the vicinity of very small amounts and in the vicinity of large flow rates.

(3) The flow rate of the fluid can be easily adjusted by changing the magnitude, pulse, frequency, etc. of the voltage applied to the piezoelectric element.

(4) Since the valve is constituted by the piezoelectric element itself, which generally has a fast response speed of several μSee to several 11 seconds, the response when controlling the fluid flow rate is good.

(5) The thickness of the piezoelectric element itself is about the same as a few micrometers of candy, allowing the entire valve structure to be made very compact.6 (6) Piezoelectric ceramics are insulators and almost no current flows, so they generate very little heat. There are few.

(7) Applying a suitable soft material to the surface of the valve body,
By forming irregularities such as grooves of appropriate shapes and dimensions on the valve body abutting portion of the valve seat, the minute flow rate of fluid can be controlled relatively easily.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining the basic structure of a piezoelectrically driven valve according to the present invention, FIG. 2 is a perspective view showing an example of the structure of a valve body, and FIG. 3 is a main part showing an example of a valve seat. A perspective view, FIG. 4 is a diagram showing the correlation between the applied voltage and the amount of displacement of the piezoelectric element,
15 and 6 are diagrams showing the correlation between the voltage applied to the pressure type element and the large flow rate in the first embodiment and the second embodiment, and FIG.
The figure is a cross-sectional view of a piezoelectrically driven valve according to the present invention in a third embodiment, and FIG. 8 is a diagram similarly showing the correlation between applied voltage and gas flow rate.

Claims (5)

[Claims] (1) In a piezoelectrically driven valve that controls the flow rate of fluid by driving a valve body using the displacement of a piezoelectric body that occurs in response to an applied voltage and seating or separating the valve body from a valve seat. A valve body made of a piezoelectric element having a piezoelectric ceramic body fixed to one surface of a thin elastic plate is installed between the main body and the housing, and a valve chamber communicating with one flow path provided in the valve body is provided. A valve seat having a valve hole communicating with the other flow path provided in the valve body is provided in the valve chamber to face the valve body, and a pressing force is applied to and removed from the valve body. A piezoelectrically driven valve characterized in that a freely adjustable adjustment mechanism is attached to the housing. (2) A piezoelectrically driven valve according to claim 1, characterized in that a soft material is adhered to the other surface of the piezoelectric element to which the piezoelectric ceramic body is fixed. (3) The piezoelectrically driven valve according to claim 1 or 2, characterized in that an unevenness such as a groove is formed on the surface of the valve seat facing the valve body. (4) The piezoelectrically driven valve according to any one of claims 1 to 3, wherein the piezoelectric element is a unimorph piezoelectric element. (5) The piezoelectrically driven valve according to any one of claims 1 to 4, wherein the fluid is a gas.