JPH0221080A - Drive control method for piezoelectric type flow regulating valve - Google Patents

Abstract

PURPOSE:To conduct flow regulation continuously and with a very simple method, by making the direction of impressed voltage a direction in which the deformation of a piezoelectric element is done so that its entrance facing surface and opposite side surface may become protrudent. CONSTITUTION:When a piezoelectric element 4 is in the state of not being impressed with voltage, it is so arranged that it is in the state of being closely welded to a plane surface portion 3a. When the piezoelectric element 4 is impressed with voltage, it makes deformation so that a surface facing the entrance portion of a low pressure side passage 2b and a surface on the opposite side may become protrudent. As a result, the piezoelectric element 4 falls into a state in which a base end fixed at a valve chamber 3 by means of a holder 5 and a free end on the opposite side come always into contact strikingly with the plane surface portion 3a. Accordingly, the size of a clearance delta between the piezoelectric element 4 and the entrance portion of the low pressure side passage 2b can be changed continuously by changing the size of impressed voltage against the piezoelectric element 4.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a piezoelectric flow rate regulating valve used for opening and closing a refrigerant gas passage, for example, to control the capacity of a compressor used in an automobile cooling system. The present invention relates to a drive control method.

[Prior art 1] Conventionally, an electrically controlled external capacity control valve was provided to change the capacity of the compressor based on an external detection signal such as engine speed, evaporator outlet temperature, or crank chamber pressure. There is something. (For example, JP-A-62-253970
It is also being considered that a bimorph type piezoelectric element (bimorph cell) is used in this external capacity control valve. Conventionally, when a bimol type piezoelectric element is used as a flow rate regulating valve, a valve is used in which one end of a high-pressure side passage 2a and a low-pressure side passage 2b of a refrigerant gas passage formed in a casing 1 is opened, as shown in FIG. Piezoelectric element 4 in chamber 3
is installed. When the applied voltage is O, the piezoelectric element 4 moves to the flat part 3a where the inlet of the low pressure side passage 2b as the fluid passage inlet is provided! It is fixed via the holder 5 in the state where it is attached. When the applied voltage is O, the piezoelectric element 4 is placed in the closed position shown by the solid line in FIG. The low-pressure side passage 2b is opened and refrigerant gas flows from the high-pressure side passage 2a to the low-pressure side passage 2b.

[Problems to be Solved by the Invention] However, in the conventional device, the piezoelectric element 4 has two positions: one in which the low-pressure side passage 2b is completely opened and the other in which it is completely closed.
Even if you try to change the gap between the piezoelectric element 4 and the flat part 3a within a minute range by changing the applied voltage in order to continuously change the flow rate, the piezoelectric element 4 can be set only in the low-pressure side passage. 2b, and it was impossible to adjust the flow rate by maintaining a small gap. Therefore, in conventional devices, it is necessary to perform duty ratio control in order to adjust the flow rate, which complicates the control and increases the number of repetitions of turning on and off the applied voltage to the piezoelectric element 4, which shortens the life of the piezoelectric element 4. There is a problem with being short. In the conventional device, the reason why the piezoelectric element 4 cannot be maintained in a state where the gap with the low voltage side passage 2b is small is that the piezoelectric element 4 is in a cantilevered state with only one end supported by the holder 5 when the piezoelectric element 4 is curved and deformed. This is considered to be because the force due to the pressure difference between the pressure at the entrance of the low-pressure side passage 2b and the pressure of the high-pressure side passage 2a cannot be overcome.

The present invention has been made in view of the above problems, and includes:
The object of the present invention is to provide a method for controlling the drive of a piezoelectric flow rate regulating valve that can continuously change the flow rate by changing the magnitude of the voltage applied to the piezoelectric element.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, when the applied voltage is O, the bimol type piezoelectric element is fixed in a state in which it is in close contact with the flat part where the fluid passage entrance part is provided. In the piezoelectric flow rate regulating valve that opens and closes a fluid passage by applying a voltage to the piezoelectric element, the direction of the applied voltage is such that the surface of the piezoelectric element opposite to the inlet portion is convex. By changing the magnitude of the applied voltage, the distance between the inlet portion and the piezoelectric element can be changed.

[Operation] In the method of the present invention, when a voltage is applied to the piezoelectric element that opens and closes the fluid passage, the piezoelectric element deforms so that the surface opposite to the inlet of the fluid passage becomes convex. In other words, since the piezoelectric element is deformed so that its both ends are in contact with the flat surface, the resistance force against the force that presses and biases the pressure-N element 4 toward the flat surface increases, and the fluid passage inlet and The distance between the piezoelectric element and the piezoelectric element can be kept small. By changing the magnitude of the applied voltage, the distance between the piezoelectric element and the fluid passage inlet section is continuously changed, and the flow rate is continuously changed.

[Example] An example embodying the present invention will be described below with reference to Fig. 1.2. The mechanical configuration of the flow rate regulating valve is the same as that of the conventional one, but the connection position of the terminal (not shown) is reversed so that the direction of the voltage applied to the piezoelectric element 4 is opposite to that of the conventional one. There is.

Now, when no voltage is applied to the piezoelectric element 4, the piezoelectric element 4 is placed in close contact with the flat part 3a, as shown in FIG. The interval between is 0, and the flow rate of the outflow regulating valve is 0. When a voltage is applied to the piezoelectric element 4, the piezoelectric element 4 deforms so that the surface opposite to the surface facing the entrance of the low-voltage side passage 2b becomes convex, unlike the conventional piezoelectric element 4. Therefore, piezoelectric element 4
The base end fixed to the valve chamber 3 by the holder 5 and the opposite free end are always in contact with the flat part 3a. or,
As shown in FIG. 2, the piezoelectric element 4 does not simply curve toward the side opposite to the low-voltage side passage 2b, but deforms so that its central portion becomes the highest. Therefore, when the distance δ between the inlet of the low-pressure side passage 2b and the piezoelectric element 4 is small, that is, the difference between the fluid pressure in the gap between the piezoelectric element 4 and the inlet of the low-pressure side passage 2b and the fluid pressure in the high-pressure side passage 2a. Even when the pressure is large, the piezoelectric element 4 can overcome the force and maintain the predetermined distance δ. Therefore, for example, when 100 V, which is equal to the applied voltage in the conventional device, is applied as shown in FIG. 1(C), the piezoelectric element 4
The distance δ from the low pressure side passage 2b is maintained at a size that does not affect the fluid flowing through the low pressure side passage 2b. When a voltage of 50 V, which is half the voltage, is applied, as shown in FIG. 1(b), the interval δ becomes approximately one-half of that value, and the flow rate of the fluid flowing into the low-pressure side passage 2h becomes small. Therefore, by changing the magnitude of the voltage applied to the piezoelectric element 4, it is possible to continuously change the magnitude of the distance δ between the piezoelectric element 4 and the inlet of the low-pressure side passage 2b, and the flow rate can be continuously changed. It becomes possible to change it.

Note that the present invention is not limited to the above embodiments,
For example, as shown in FIG. 3, the high-pressure side passage 2a may be formed on a separate wall from the low-pressure side passage 2b, or it may be embodied in a piezoelectric flow rate regulating valve used in a device other than a compressor.

[Effects of the Invention] As detailed above, according to the present invention, the distance between the piezoelectric element and the fluid passage inlet can be continuously changed according to the magnitude of the applied voltage, so that flow rate adjustment is not complicated. Instead of controlling the duty ratio, which requires constant control, it can be done continuously by changing the magnitude of the applied voltage. This has the excellent effect of reducing the number of repeated deformations, resulting in a longer lifespan of the piezoelectric element.

[Brief explanation of the drawing]

Figures 1 <a> to (C) are cross-sectional views showing the action, Figure 2 is a perspective view of the condyle tract showing the deformed state of the piezoelectric element, Figure 3 is a cross-sectional view of a modified example, and Figure 4 is a view of the conventional device. It is a sectional view showing an effect. Low pressure side passage 2b as a fluid passage, valve chamber 3, flat part 3a
, piezoelectric element 4, spacing δ. Patent applicant Toyota Industries Corporation Representative Patent attorney On 1) Boyo 3rd J! 1 Figure 4

Claims (1)

[Claims] 1. fixing the bimol type piezoelectric element in close contact with a flat surface provided with a fluid passage inlet when an applied voltage is 0;
In the piezoelectric flow rate regulating valve that opens and closes a fluid passage by applying a voltage to the piezoelectric element, the direction of the applied voltage is such that the piezoelectric element has a surface facing the inlet portion and a surface opposite to the inlet portion having a convex surface. A drive control method for a piezoelectric flow rate regulating valve, in which the distance between the inlet portion and the piezoelectric element is changed by changing the magnitude of the applied voltage.