JPS59229155A - dryness control expansion valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Aspects of the Invention] The present invention relates to an expansion valve used in refrigeration equipment such as refrigerators and air conditioners. This invention relates to a dryness control expansion valve that controls dryness.

[Background of the invention]

The expansion valve installed in the refrigerant circuit of refrigerators, air conditioners, etc.
The temperature of the refrigerant at the exit side of the evaporator is detected, the valve opening degree is adjusted, and the refrigerant flow rate is controlled so that the temperature is maintained at an appropriate degree of superheat.

Figure 1 shows the most basic refrigerant circuit used in refrigerators and air conditioners. 1 is a compressor, 2 is a condenser, 3 is a thermostatic automatic expansion valve, and 4 is an evaporator. The above-mentioned devices are sequentially connected through piping to form a refrigerant circuit as shown in the figure.

The gas refrigerant is heated to high temperature and high EE by the compressor 1, and is led to the condenser 2 through the refrigerant pipe 5. The refrigerant liquefied while dissipating heat in the condenser undergoes adiabatic expansion through the valve passage of the expansion valve 3, resulting in low flow and low pressure. Next, the refrigerant led to the evaporator 4 absorbs heat from the surroundings, vaporizes, and returns to the compressor 1 again. Here, the opening degree of the expansion valve 3 is controlled by detecting the temperature of the refrigerant on the exit side of the evaporator 4 obtained by the heat-sensitive tube 6 and using it as a signal to maintain the temperature at an appropriate degree of superheat. Generally, in order to operate this type of expansion valve stably, it is necessary to stabilize the temperature detected by the heat sensitive cylinder 6. For this reason, in the conventional expansion valve, the refrigerant at the outlet of the evaporator 4 has to be overheated to a certain degree or more. However, this restriction has caused the following problems. The first point is a decrease in the performance of the evaporator 4. The heat transfer coefficient of the gas refrigerant is Since it is extremely small compared to the heat transfer volume, the increase in the superheat area means that the average heat transfer rate of the evaporator is reduced.The second point is that the mass flow rate of the refrigerant is reduced, which reduces the efficiency. This results in a reduction in the amount of heat exchange.

In order to maintain (or increase) the refrigerant mass flow rate, an increase in compressor capacity is required.

There were two problems as described above.

[Purpose of the invention]

The present invention was invented in view of the above problems, and an object of the present invention is to provide an expansion valve that can detect the degree of dryness of a refrigerant and arbitrarily control this degree of dryness.

[Summary of the invention]

In order to realize a dry production #expansion valve, it is important to accurately detect the degree of dryness of the refrigerant. We theoretically and experimentally investigated several types of sensing methods and found that the capacitance variation method, which focuses on the difference in dielectric constant between refrigerant gas and liquid, is effective. In order to achieve the object, the present invention focuses on the above-mentioned capacitance change method, and provides a dryness detection sensor consisting of a pair of electrodes in the passage from the evaporator to the compressor of the refrigerant circuit. It is characterized in that the detected capacitance signal is converted into voltage or current via a converter, and this voltage or current is introduced to a drive mechanism that drives the opening of the expansion valve to control the opening of the expansion valve.

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 2, a compressor 1, a condenser 2, an expansion valve 3, an evaporator 4
As in FIG. 1, the pipes are successively connected to form a refrigerant circuit. A sensor 12 is provided in the suction passage 1o leading from the evaporator 4 to the compressor 1, and this sensor 12 is connected to a converter 13 and further connected to the expansion valve 3 via a drive mechanism 14. The converter 13 is a mechanism that converts capacitance information obtained from the sensor 12 into voltage or current. There is no particular meaning in the present converter 13 existing independently, and there is no problem in having it attached to the sensor 12 or the drive mechanism 14. The drive mechanism 14 is a mechanism that changes the opening degree of the expansion valve 3 according to the magnitude of the voltage and current sent from the converter 13. The opening degree of the expansion valve 3 is changed by a drive mechanism 14 . The structure of the sensor 12 is shown in FIGS. 3 to 6. The examples shown in FIGS. 3 and 4 are composed of a combination of a cylindrical electrode 21 and a rod-shaped electrode 22.

An appropriate length range of the passage 10 is formed with an insulator 10a, and a cylindrical electrode 21 of an appropriate length is arranged on the inner wall of the insulating passage 10a or in the middle of the insulating passage. A rod-shaped electrode 2 having a slightly longer length than the cylindrical electrode 21
2 is placed.

The rod diameter of the rod-shaped electrode 22 is set to a diameter that does not affect the flow of the fluid. 21a122a indicates terminals of both electrodes.

FIGS. 5 and 6 show another embodiment of the sensor, in which it is formed by a pair of arcuate electrodes 23, 24. An appropriate length range of the passage 1o is formed with an insulator 10a, and the insulating passage 10a is
A pair of arc-shaped electrodes 2 are installed on the inner wall of the
3.24 are placed facing each other with a gap between both electrodes. 23
&, 24a indicate terminals of both electrodes. FIG. 7 shows yet another embodiment of the sensor, in which a pair of arcuate electrodes 23, 24 and a similar pair of arcuate electrodes 25, 26 are arranged 90 degrees apart.

The above-mentioned two pairs of electrodes are disposed within an appropriate length range of the passage 10a, covering the entire range of the plane perpendicular to the direction of fluid flow. The pair of electrodes is located at the same position.

Next, the operation of this embodiment will be explained. In the refrigerant circuit shown in FIG.
generates different signals depending on whether the internal refrigerant is 100% gas, 100% liquid, or a two-phase flow. The principle is that the dielectric constants of gas refrigerant and liquid refrigerant are different. Now, assuming that the dielectric constant of the gas refrigerant is 6g and the dielectric constant of the liquid refrigerant is εg, the capacitances of the gas and liquid Cg and C1 are as follows: Cg=εg−A/Lg・・・・・・・・・・・・・・・...
(1) CI-εg -A/L l・・・・・・・・・
...It is illuminated by (2). Here, A is the electrode plate area, Lg.

Ll is the thickness of the gas layer and the liquid layer, respectively (the above relationship assumes parallel plate electrodes). Assuming that the gas layer and liquid layer are separated into upper and lower parts, the total capacitance C can be calculated using equations (1) and (2) as follows: C=1/(↓□Judo) 0g C1 = εg, εd-A/(ε#-Lg+εg-L6)-εg
-εl-A/[(εeO+εg-(1-2)) L)=
εg−εg −;/ (εe−a+εtx, CA-2)
)・----・(3). Here L=Lg+L11
0 (void)=Lg/L. For refrigerant εg >>
Since εg, by setting 67=neg, equation (3) becomes as follows. (n>1) That is, the capacitance C and the void volume (gas volume fraction) 0 have an inversely proportional relationship as shown in equation (4).

When the shape of the electrode changes, the form of equation (4) changes, but the tendency for the relationship between C and α does not change. Therefore, FIG. 8 shows an example of the relationship between C and α. Although FIG. 8 is determined theoretically with respect to the shape of the electrode, there may be factors that are not included in the calculation, so it is best to confirm it by experiment.

The information on the capacitance obtained by the sensor 12 is sent to the converter 13! It is converted into a voltage or current and transmitted to the drive mechanism 14. The drive mechanism 14 adjusts the opening degree of the expansion valve so that the information becomes equal to the initial setting of the degree of freshness.

By the above-described operation, an expansion valve that can arbitrarily adjust the degree of freshness of the refrigerant at the evaporator outlet can be realized.

〔Effect of the invention〕

As explained above, according to the present invention, the degree of refrigerant in the evaporator outlet pipe in the refrigerant circuit can be arbitrarily controlled by the expansion valve. As a result, the following effects can be obtained.

Since there is no need to superheat the refrigerant inside the evaporator,
Heat transfer rate is greatly improved. Furthermore, since the refrigerant superheat at the compressor suction port can be reduced, the mass flow rate of the refrigerant increases and the amount of heat exchange increases. If the amount of heat exchange is the same as the conventional one, the compressor capacity can be reduced and the system can be powered. Furthermore, since the degree of purity of the suction port refrigerant can be set to a specific value, the efficiency of the compressor (% fixed model) is improved.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram using a conventional expansion valve, Fig. 2 is a refrigerant circuit diagram equipped with a dryness control expansion valve showing an embodiment of the present invention, and Fig. 3 is an embodiment of a sensor. The front view and FIG. 4 show a sectional view taken along the line ■-■ in FIG. 3. Fig. 5 is a front view showing another embodiment of the sensor, Fig. 6 is a sectional view taken along the line ■-■ of Fig. 5,
FIG. 7 shows a perspective view showing still another embodiment of the sensor,
FIG. 8 is a characteristic diagram of the sensor. 1... Compressor 2... Condenser 3... Expansion valve 4
... Evaporator 10... Passage 10a... Insulation passage 12... Sensor 13... Exchanger 14... Drive mechanism 21.22.23.24.25.26... Electrode 1st m Age 2m No. q Kasumi

Claims (1)

[Claims] 1. A sensor consisting of a pair of electrodes is provided in a passage leading from the evaporator to the evaporator of a refrigerant circuit formed by sequentially connecting an E-condenser, a condenser, an expansion valve, and an evaporator; A dryness control expansion valve that connects the sensor to the expansion valve via a converter and a drive mechanism, and controls the opening degree of the expansion valve by exploiting the capacitance between the two electrodes. 2. The dryness according to claim 1, wherein the pair of electrodes is a cylindrical electrode of an appropriate length forming a passage wall, and a rod-shaped electrode provided in the central part of the cylindrical cage in the axial direction. Controlled expansion valve. 3. The dryness control expansion valve according to claim 1, wherein the pair of electrodes is formed of arcuate opposed electrodes of appropriate length. 4. The dryness control expansion valve according to claim 3, wherein a plurality of pairs of electrodes are provided at different angles. 5. The dryness control expansion valve according to claim 1, wherein the converter converts the sensor signal into voltage or current. 6. The dryness control expansion valve according to claim 1, wherein the drive mechanism is linked to the expansion valve and controls the valve opening.