JPH0719668A - Expansion valve - Google Patents

Abstract

PURPOSE:To obtain an expansion valve having a fast throttling speed and a low operating noise by providing a piezoelectric element and varying the sectional area of a channel of fluid with the displacement of the element as the displacement of a diaphragm. CONSTITUTION:When a pulse voltage is applied to a piezoelectric actuator 30 as a piezoelectric element of an expansion valve 11 and the actuator 30 is longitudinally elongated, an upper end plate 33 is displaced, and the interval D1 between the plate 33 and a partition plate 24 is reduced. The volume of a second operating chamber 35 is reduced, and the operating medium 36 is pressurized by the plate 33. Further, a diaphragm 36 is pressed by the medium 36 to be deformed, and the volume of a first operating chamber 29 is increased. The diaphragm 27 protrudes into a refrigerant flowing space 14, and the interval between the diaphragm 27 and a first refrigerant guide 15 is narrowed. This interval defines the refrigerant flowing area, i.e., the flow rate. Accordingly, the response speed is faster and the operating noise is lower as compared with the case in which a thermal or mechanical transmission mechanism is used to transfer power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion valve used as an automatic throttle valve of a refrigeration cycle, for example.

[0002]

2. Description of the Related Art For example, a temperature-sensitive tubular heat transfer expansion valve is known as an automatic throttle valve 2 used in a refrigeration cycle 1 as shown in FIG. This type of expansion valve has the advantage of low cost, but has the drawback of slow response speed. In particular, when this expansion valve is simply combined with an air conditioner of the type in which the rotation frequency of the compressor 3 can be freely controlled, the throttle speed does not keep up with changes in the rotation frequency of the compressor, and an optimum cycle is realized. Is difficult.

Here, reference numeral 4 in FIG. 4 indicates an indoor heat exchanger, and reference numeral 5 indicates an outdoor heat exchanger. Further, reference numeral 6 indicates a four-way valve. A pulse motor valve (hereinafter referred to as PMV) is an example of a valve mechanism that replaces the temperature-sensitive tubular heat transfer expansion valve described above. The features of PMV are that the throttle speed is fast and the opening can be controlled finely from fully open to fully closed. However, this PMV
However, there is a problem in that the cost is high and a rattling sound of the plunger is generated when the valve position is initialized.

[0004]

As described above, the conventional temperature-sensitive tubular heat transfer expansion valve has a problem that it is difficult to combine it with a variable capacity air conditioner because of its slow response speed. Further, while PMV has an advantage that the reaction speed is fast and a fine opening degree control is possible, it has a problem that the cost is high and the operation sound at the time of initializing the valve position is large.
The object of the present invention is that the squeezing speed is high, and
It is to provide an expansion valve with a quiet operating sound.

[0005]

In order to achieve the above object, the present invention is provided with a piezoelectric element, and the displacement of this piezoelectric element is used as the displacement of the diaphragm to change the flow passage cross-sectional area. By doing so, the present invention aims to increase the aperture speed and reduce the operating noise.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1A shows an embodiment of the present invention, in which reference numeral 11 is an expansion valve. This expansion valve 1
1 has an upper case 12 and a lower case 13. Both cases 12 and 13 are combined vertically and joined to each other in an airtight manner. The plane shape of the upper case 12 is a perfect circle, and a space 14 for circulating the refrigerant is formed inside the upper case 12.

Further, the upper case 12 is provided with first and second tubular refrigerant guide portions 15 and 16. First
The refrigerant guide portion 15 is located substantially at the center of the upper case 12 and projects to the front and back of the top plate 17. The first and second coolant ports 18 and 1 are provided at both axial ends of the first coolant guide portion 15.
9 is open, and the first coolant guide portion 15 communicates with the internal space 14 of the upper case 12 through the second coolant port 19.

Further, the second refrigerant guide portion 16 has an upper case 1
From the side surface of 2, it protrudes substantially horizontally along the radial direction.
The first refrigerant is provided at both axial ends of the second refrigerant guide portion 16.
And the second refrigerant ports 20 and 21 are opened, and the second refrigerant guide portion 16 is connected to the upper case 12 via the second refrigerant port 21.
Communicates with the internal space 14 of the.

Refrigerant piping (not shown) of the refrigeration cycle is connected to both the refrigerant guide portions 15 and 16. Then, the refrigerant gas as the fluid of the refrigeration cycle passes through the internal space 14 of the upper case 12 as shown by the arrow A or the arrow B via the first and second refrigerant guide portions 15 and 16.

The lower case 13 is a cylindrical outer case 22.
And a bottom case 23 in which the bottom of the outer case 22 is closed. Further, the outer case 22 is joined to the upper case 12 with a disc-shaped partition plate 24 interposed.

An outer peripheral edge portion of the partition plate 24 is fitted to a boundary portion between the upper case 12 and the lower case 13, and both cases 12, 1 are provided.
Held by 3. Further, the partition plate 24 is formed with an operation medium introducing hole 25, and the introducing hole 25 extends along the axis of the partition plate 24. The operating medium introducing hole 25 is opened on both plate surfaces of the partition plate 24. Further, an annular protrusion 26 is formed on the partition plate 24, and the protrusion 26 projects toward the upper case 12.

The protrusion 26 of the partition plate 24 is a diaphragm 27.
Are covered by. The diaphragm 27 is formed by forming a thin metal plate into a perfect circular shape, and hides the opening of the operating medium introducing hole 25. The diaphragm 27 is fixed to the protrusion 26 by a fixing ring 28 while the peripheral portion of the diaphragm 27 is in contact with the outer peripheral surface of the protrusion 26. In addition, the diaphragm 2
7 and the protrusion 26 are sealed so that there is no liquid leakage. A first working chamber 29 is formed inside the diaphragm 27, and the first working chamber 29 communicates with the working medium introducing hole 15.

The diaphragm 27 and the first refrigerant guide portion 15
Is approaching. The distance D between the two shown in FIG.
₁ determines the flow passage cross-sectional area of the refrigerant. As shown in FIG. 1, a piezoelectric actuator (hereinafter, referred to as an actuator) 30 as a piezoelectric element is housed in the lower case 13. The actuator 30 is a laminated vertical type,
In this actuator 30, ceramic plates and thin metal plates are alternately laminated.

The actuator 30 is connected to the bottom case 23 and is supported by the bottom case 23. The actuator 30 and the outer case 22 are separated by a gap 31 so that they are not rigidly joined. Further, the electrode wire 32 connected to the actuator 30 is
It penetrates through the bottom case 23 and is led out to the outside of the lower case 13.

An upper end plate 33 is attached to the actuator 30, and the upper end plate 33 faces the partition plate 24 while being separated therefrom. Further, an annular seal member 34 is interposed between the upper end plate 33 and the partition plate 24, and both plate 3
A second operation chamber 35 is formed between the third and the third holes 24. Here, in this embodiment, as the seal material 34, an O-ring made of a material having appropriate elasticity such as rubber is adopted.

The second working chamber 35 communicates with the working medium introducing hole 25, and also communicates with the first working chamber 29 through the working medium introducing hole 25. These second operation chamber 3
5, the introduction hole 25, and the first operation chamber 29 are filled with the operation medium 36, and the operation medium 36 is sealed between the upper end plate 33 and the diaphragm 27. An incompressible fluid such as oil is used as the working medium 36.

The volume of the second working chamber 35 is equal to that of the first working chamber 2.
It is set sufficiently larger than the volume of 9. That is, _assuming that the cross-sectional area of the second operation chamber 35 is S _s and the cross-sectional area of the operation chamber is S _d , there is a relationship of S _S >> S _d between them.

Next, the operation of the expansion valve 11 will be described. First, a voltage (for example, pulse voltage) is applied to the actuator 30, and the actuator 30 is displaced in the vertical direction. The displacement amount (length) of the actuator changes in proportion to the supply voltage. For example, when a DC voltage of 400 V is applied to the actuator 30, the displacement amount is about 40 μm.
Various general techniques can be adopted as the drive circuit and drive system of the actuator 30.

When the actuator 30 extends, the upper end plate 3
3 is displaced, and the distance D ₂ between the upper end plate 33 and the partition plate 24 is reduced. The volume of the second working chamber 35 decreases, and the working medium 36 is pushed by the upper end plate 33. Further, the working medium 36 pushes the diaphragm 27, the diaphragm 27 is deformed, and the volume of the first working chamber 29 increases. And
The diaphragm 27 projects into the space 14 for circulating the refrigerant, and the distance D ₁ between the diaphragm 27 and the first refrigerant guide portion 15 is narrowed.

The diaphragm 27 and the first refrigerant guide portion 15
The distance D ₁ between the flow path and the flow path determines the flow passage area of the refrigerant, that is, the flow rate. Therefore, when D ₁ is narrowed, the flow passage area of the refrigerant is reduced and the refrigerant flow rate between the refrigerant guide portions 15 and 16 is also reduced.

Here, the initial value of D ₁ is determined according to the amount of deformation of the diaphragm and the desired flow rate of the refrigerant.
On the other hand, when the actuator 30 contracts, the distance D ₂ between the upper end plate 33 and the partition plate 24 expands, and the volume of the second working chamber 35 increases. Further, the operation medium 36 is the second operation chamber 35.
The diaphragm 27 moves to meet the operating medium 3
Deforms following # 6. Then, the diaphragm 27 is recessed, and the distance D ₁ between the diaphragm 27 and the first refrigerant guide portion 15 is expanded. As a result, the flow passage area of the refrigerant increases, and the refrigerant flow rate between the refrigerant guide portions 15 and 16 also increases.

Since the working medium 36 is an incompressible fluid,
The second working chamber 3 when the actuator 30 is driven
The volume change amount of No. 5 and the volume change amount of the first operation chamber 29 match. Therefore, if the displacement of the diaphragm is δ _d when the displacement of the actuator is δ _S , then S _s ·
The relationship of δ _s = S _d · δ _d is established. The displacement amount of the diaphragm is represented by δ _d = (S _s / S _d ) δ _s .

That is, the displacement amount of the actuator 27 is amplified via the operating medium 36. Therefore, even if the displacement amount of the actuator 30 is several tens of μm (for example, 40 μm), the diaphragm 27 is displaced sufficiently to a sufficient extent as a diaphragm of the expansion valve. And diaphragm 2
The displacement amount of No. 7 is determined according to the volume ratio of the first working chamber 29 and the second working chamber 35.

In such an expansion valve 11, the actuator 30 is used, and the displacement of the actuator 30 is transmitted to the diaphragm 27 via the operating medium 36. The actuator 30 is an electronic circuit element that does not use a mechanical operation part, and the displacement of the actuator 30 is transmitted to the diaphragm 27 using an incompressible operation medium. Therefore, the response speed is faster than that in the case where heat or a mechanical transmission mechanism is used to transmit power. Further, since a plunger such as a pulse motor valve (PMV) is not used, the operating noise is low and the operation is quiet.

In the present embodiment, the diaphragm 27 is fixed to the partition plate 24 by the fixing ring 28, but the present invention is not limited to this. For example, the diaphragm 27 is welded to the partition plate 24. You may fix it using the means of.

Further, in this embodiment, the diaphragm 27 directly changes the flow passage cross-sectional area of the refrigerant, but for example, a needle for adjusting the flow passage cross-sectional area can be attached to the diaphragm 27.

Further, it is possible to employ various general ones as the laminated vertical type actuator 30.
Further, the piezoelectric actuator 30 is not limited to the laminated vertical type, and various general piezoelectric actuators can be adopted.

[0028]

As described above, the present invention is provided with a piezoelectric element, and the displacement of the piezoelectric element is used as the displacement of the diaphragm to change the flow passage cross-sectional area. Therefore, the present invention has the effect of increasing the aperture speed and reducing the operating noise.

[Brief description of drawings]

FIG. 1 shows an expansion valve according to a first embodiment of the present invention,
(A) is a sectional view and (b) is a plan view from above.

2A is a plan view from below, FIG. 2B is FIG.
Sectional drawing which followed the IV-IV line in (a).

FIG. 3A is a graph showing the relationship between the force and strain of a piezoelectric actuator, and FIG. 3B is a graph showing the relationship between voltage and strain.

FIG. 4 is an explanatory view showing a gap between a diaphragm and a first refrigerant guide portion.

FIG. 5 is an explanatory view showing a cross-sectional area of a first operation chamber.

FIG. 6 is an explanatory view showing a cross-sectional area of a second operation chamber.

FIG. 7 is a configuration diagram schematically showing a general refrigeration cycle.

[Explanation of symbols]

11 ... Expansion valve, 27 ... Diaphragm, 29 ... First working chamber, 30 ... Piezoelectric actuator (piezoelectric element), 35 ... Second working chamber, 36 ... Working medium.

Claims (3)

[Claims] 1. An expansion valve comprising a piezoelectric element, wherein the displacement of the piezoelectric element is used as the displacement of a diaphragm to change the cross-sectional area of a fluid passage. 2. An expansion device comprising: a piezoelectric element; an operating medium that receives a force generated by displacement of the piezoelectric element; and a diaphragm that receives a force from the operating medium and changes a flow passage cross-sectional area of a fluid. valve. 3. A first working chamber and a second working chamber communicating with each other, a working fluid enclosed in these working chambers, and the first working chamber.
Expansion including a piezoelectric element that changes the volume of the working chamber and a diaphragm that operates by receiving a force from the working fluid and that changes the volume cross-sectional area of the fluid while changing the volume of the second working chamber. valve.