JPS63219972A - Valve drive device - Google Patents

Abstract

PURPOSE:To make precise control having no unoperating region by regulating the opening of valve according to expansion/shrinkage quantity of a piezoelectric element. CONSTITUTION:A valve seat 5, a valve body 6 facing with the valve seat 5 and a valve rod 7 for supporting the valve body 6 from the opposite side of the valve seat are arranged in a valve box 3. A driving quantity transmitting means for driving the valve rod 7, i.e. a drive shaft 10, is contacting with the end portion of the valve rod 7 at the opposite side from the valve body, and coupled with a group of piezoelectric elements 11 were plural sheets of piezoelectric elements 11a are laminated in series. When control voltage is applied onto respective inner electrodes 12a, 12b, respective piezoelectric elements 11a expand according to the applying voltage so as to advance the valve body 6 with respect to the valve seat.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a valve driving device installed in a flow path to control the flow rate and pressure of a fluid, and more specifically, to an electric refrigerator or an air conditioner. The present invention relates to a valve drive device suitable for expansion valves in cooling cycle systems such as the like.

[Conventional technology]

In refrigeration cycle systems such as electric refrigerators and air conditioners, capillary tubes and thermostatic expansion valves have been conventionally used to expand refrigerant and lower the temperature.

However, the capillary tube has a constant expansion ratio, and the temperature-type expansion valve has a large opening/closing temperature error, so it has the disadvantage of slow response to temperature changes.

For this reason, an electronically controlled expansion valve controlled by a pulse motor is generally adopted as an expansion valve for an electric refrigerator or an air conditioner controlled by an inverter. This electronically controlled expansion valve driven by a pulse motor rotates a pulse motor using switched pulses, rotates a drive screw via a reduction gear, and adjusts the amount of advance and retraction of this drive screw to a valve body supported by a bellows. The valve opening was controlled by transmitting the information.

[Problem that the invention seeks to solve]

However, the above-mentioned control method using an electronically controlled expansion valve driven by a pulse motor has a problem in that it is inevitably expensive because it uses driving parts and mechanical parts such as a pulse motor and gears. Also.

Since gears are used, there is a problem in that it is impossible to eliminate non-operating areas caused by backlash. This invention was made in view of the above technical background, and its purpose is to provide an inexpensive, Another object of the present invention is to provide a valve driving device that has no non-operating area and can be precisely controlled.

[Means for solving problems]

In order to solve the above object, the present invention provides a valve body installed in a flow path of a fluid to be controlled, and a support means for supporting the valve body so as to be freely advanced and retracted with respect to a valve seat.

A valve driving device comprising a valve driving means for advancing and retracting the valve body with respect to a valve seat, wherein the valve driving means includes a piezoelectric element stacked with a plurality of piezoelectric elements with electrodes inserted on both end faces thereof; It is comprised of a control voltage supply means for supplying a voltage for controlling the amount of expansion and contraction of the piezoelectric element, and a drive amount transmission means for transmitting the expansion and contraction of the piezoelectric element to the valve body.

[For production]

According to the above means, the valve body can be driven, that is, the valve opening degree can be adjusted according to the amount of expansion and contraction of the piezoelectric element, which expands and contracts itself.Therefore, there is no backlash, and there is no need for expensive drive parts or mechanical parts. becomes unnecessary. Further, by appropriately setting the number of stacked piezoelectric elements and the driving voltage to be applied depending on the opening degree of the target valve device, it is possible to correspond to the required valve opening degree.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a cross-sectional view of the valve device according to this embodiment, and FIG. 2 is an explanatory diagram showing the structure of a piezoelectric element constituting the drive device.

In FIG. 1, the valve device, also called an expansion valve, according to this embodiment is often used in refrigerators and air conditioners, and includes a valve housing 3 provided between pipes 1 and 2, and a valve device attached to this valve housing 3. It consists of a valve drive device 4.

Inside the valve housing 3, there is a valve seat 5 disposed at the end of one of the pipes 1, a valve body 6 disposed opposite to the valve seat 5, and a valve body 6 that supports the valve body 6 from the side opposite to the valve seat. A valve stem 7 and a bellows 8 supporting the second valve element 7 are provided, and the bellows 8 allows the valve element 6 to move forward and backward relative to the valve seat 5 within the valve chamber 9.

A drive shaft 10 as a drive amount transmission means for driving the valve stem 7 is in contact with the end of the valve body 7 on the side opposite to the valve body, and this drive shaft 10 is further made of a thin plate of electrostrictive ceramics, for example. It is connected to a piezoelectric element group 11 formed by stacking a plurality of piezoelectric elements 11a in series, and is housed in a housing 4a. An adjustment screw 14 whose portion abuts against the piezoelectric element group 11 is provided.

A part of this piezoelectric element group 11 is enlarged. Referring to FIG. 2, internal electrodes 12a and 12b are arranged on both end faces of each voltage element 11a, and these internal electrodes 12a and 12b are connected to external electrodes 13a and 13b, respectively. In this example, each internal electrode 12a is connected to an external electrode 13a, and each internal electrode 12b is connected to an external electrode 13b. 12
Insulators 18a and 18b are inserted into the portions where b and external electrode 13a are in contact, respectively, to prevent short circuits between internal electrode 12a and external electrode 13b, and between internal electrode 12b and external electrode 13a. As a result, both internal electrodes 12a, 1
2b is formed in a so-called comb-teeth shape.

A control voltage is applied to each piezoelectric element 11 from a control voltage supply device 17 to the external electrodes 13a and 13b via conductive wires 15 and 16.
It is designed to be supplied in parallel to the internal electrodes 12a and 12b of a. The control voltage supplied from the control voltage supply means consisting of these conductors 15 and 16 and the control voltage supply device 17 is controlled by commands from a central processing unit (not shown), which is equipped with a microprocessor equipped with a temperature sensor. When the rotational speed of the compressor is changed by, for example, the rotation speed of the compressor is changed, the voltage for controlling the opening degree of the valve body 6 is instructed to the control voltage supply device 17 so that a corresponding appropriate flow rate of refrigerant flows. The required control voltage is generated depending on the instruction.

In this way, the control voltage is the same as each internal voltage 12a.

12b, each voltage element 11a expands according to the applied voltage, and as a result, the total elongation of the stacked piezoelectric element group 11 is applied to the valve stem 7 via the drive shaft 10.
is pressed, the valve body 7 moves in the direction of the valve seat 5 against the elastic force of the bellows 8, and the valve body 6 is advanced toward the valve seat S. Thereby, a desired valve opening degree can be set, and furthermore, the valve body 6 can be brought into contact with the valve seat 5 to close the valve. At this time, the elongation of the piezoelectric elements 11a and llb is determined by the applied voltage, so if the correlation between the applied voltage and the elongation is established in advance and programmed in the central processing unit, the elongation can be adjusted according to the required valve opening degree. Voltage is supplied from the control voltage supply device 17, thereby making it possible to constantly control the valve opening to an appropriate value.

In this way, according to the above embodiment, the stacked piezoelectric element group 1
By applying the required voltage to each piezoelectric element 11a of 1, it is now possible to freely set the valve opening degree, resulting in the following effects.

■Quick response to all fluctuations in the refrigeration cycle.

■Since no mechanical parts such as gears are used, there is no crushing and the control accuracy is excellent.

■Costs are lower because drive parts and mechanical parts such as motors and gears are not required.

■By selecting the number of piezoelectric elements 11a to be stacked,
Since the valve opening range can be freely set, it is extremely easy to accommodate the required control range.

(2) Therefore, it is possible to accurately perform optimal control in extreme operating conditions without time delay over the entire set control range.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, which includes a layered piezoelectric element group and is configured to drive a valve by applying a voltage to each piezoelectric element of the piezoelectric element group, the driving parts and mechanism Because no parts are required.

It is possible to provide a highly accurate valve drive device that is inexpensive, has no non-operating area, has excellent responsiveness, and can be precisely controlled according to the applied voltage.

[Brief explanation of drawings]

All figures are for detailed explanation of this invention.
The figure is an explanatory view showing the cross-sectional structure of the valve device, and FIG. 2 is an explanatory view showing the structure of the piezoelectric element in cross-section. In the figure, 5 is a valve seat, 6 is a valve body, 7 is a valve stem, 8 is a bellows,
10 is a drive shaft, 11 is a piezoelectric element group, lla is a piezoelectric element,
12a and 12b are internal electrodes, 13a and 13b are external electrodes, 15 and 16 are conductive wires, and 17 is a control voltage supply device. Patent applicant: Fujitsu General Co., Ltd. Representative, Patent attorney: Takuya Ohara Figure 1 Figure 2 @

Claims (2)

[Claims] (1) A valve body installed in a flow path of a fluid to be controlled, and supporting means that supports the valve body so as to be freely advanced and retracted from the valve seat;
and a valve driving means for advancing and retracting the valve body with respect to the valve seat, the valve driving means comprising:
a plurality of piezoelectric elements laminated with electrodes inserted into both end faces; control voltage supply means for supplying voltage to the electrodes for controlling the amount of expansion and contraction of the piezoelectric element; and expansion and contraction of the piezoelectric element. a driving amount transmitting means for transmitting the amount of drive to the valve body. (2) The valve driving device according to claim (1), wherein the piezoelectric element is housed in a housing, and the housing is provided with an adjustment screw for setting an initial position.