JP2915537B2 - How to determine the amount of refrigerant in the refrigerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for determining the amount of refrigerant charged in a refrigerator.

[Conventional technology]

FIG. 7 is a system diagram of a refrigerator showing a conventional method of determining the amount of charged refrigerant. In the figure, 1 is a compressor, 2 is a four-way valve connected to the compressor, 3 is an indoor heat exchanger connected to the four-way valve, 4 is a throttle connected to the indoor heat exchanger 3, and 5 is connected to the same throttle 4. And an outdoor heat exchanger connected to the four-way valve 2, 6 is a discharge pipe of the compressor 1, 7 is the same suction pipe, and 17 and 18 are sight glasses provided on pipes before and after the throttle 4. The solid arrows and the solid lines in the four-way valve 2 in the figure show the flow of the refrigerant during the heating operation, and the broken arrows and the broken lines in the four-way valve 2 in the figure show the flow of the refrigerant during the cooling operation.

The refrigerator includes a four-way valve 2 connected to the compressor 1 via a discharge pipe 6 and a suction pipe 7 and an indoor heat exchanger 3 and a throttle 4.
And the outdoor heat exchanger 5 are sequentially connected to form a closed-cycle refrigeration cycle. During the cooling operation, the refrigerant discharged from the compressor 1 is supplied to the four-way valve 2 as shown by a dotted line in FIG. The refrigerant returns to the compressor 1 via the outdoor heat exchanger 5, the throttle 4, the indoor heat exchanger 3, and the four-way valve 2 to cool the room. In the heating operation, the refrigerant discharged from the compressor 1 as shown by a solid line in the figure. Returns to the compressor 1 through the four-way valve 2, the indoor heat exchanger 3, the throttle 4, the outdoor heat exchanger 5, and the four-way valve 2, and heats the room. The throttle 4 adjusts the flow rate of the refrigerant to the required flow rate during cooling and during heating, respectively. By the above operation, cooling and heating operations are performed. The sight glasses 17 and 18 are used to determine whether or not the amount of the refrigerant charged in the refrigerator is appropriate. In the refrigeration cycle, the amount of the charged refrigerant is in the low charge state or the refrigerant gas leakage state. In FIG. 8, as shown in FIG. 8, the judgment is made by utilizing the phenomenon that the degree of supercooling becomes equal to or less than zero and the refrigerant liquid is in a flash state before the throttle 4. It is to judge whether the amount of filling is proper or low charge. The sight glasses 17 and 18 before and after the aperture 4 are provided so as to be used separately for heating and cooling.

[Problems to be solved by the invention]

In the conventional determination method, when the amount of charged refrigerant is overcharged, the refrigerant in front of the throttle 4 is not flushed as in the case of proper charging, and therefore, it is determined even though the charged amount is not appropriate. I couldn't do that. Further, even when the amount of charged refrigerant is appropriate, the refrigerant in front of the throttle 4 may flash depending on the combination of the indoor temperature and the outdoor temperature, and the determination may not be performed normally. Furthermore, it has not been possible to quantitatively determine what percentage of the refrigerant charge is present.

On the other hand, as shown in FIG. 9, the operating state of the connection pipe varies depending on the length relative to the standard length. Therefore, it is possible to determine the refrigerant charging amount normally only by the flush state of the refrigerant before the throttle 4. It cannot be done. Especially in refrigerators used for air conditioners for buildings, etc., the connection pipe length is extremely long, such as 300 m at the maximum, so the influence of the pipe length is great, and this point must be considered.

An object of the present invention is to provide a method for accurately and quantitatively determining the amount of refrigerant to be charged while taking into account the influence of the connection pipe length ratio.

[Means for solving the problem]

The present invention has solved the above-mentioned problem, and previously obtained a relational expression between the indoor temperature, the outdoor temperature, the suction superheat degree and the discharge superheat degree, and the refrigerant encapsulation rate and the connection pipe length ratio, thereby obtaining the indoor temperature and the outdoor temperature. Refrigerant charging of a refrigerator characterized by calculating a refrigerant charging ratio and a connection pipe length ratio from a measured value of a temperature and a calculated value of a suction superheat degree and a discharge superheat degree, and judging a refrigerant charging amount from the refrigerant charging ratio. It relates to a method for determining the amount.

[Action]

The relational expressions of the indoor temperature, the outdoor temperature, the suction superheat degree and the discharge superheat degree, the refrigerant encapsulation rate and the connection pipe length ratio, which have been obtained in advance, are stored in, for example, a determination device.

The indoor temperature and the outdoor temperature are measured by a temperature sensor. The suction superheat degree and the discharge superheat degree are calculated in the determination device based on the measured value and the pressure measured value obtained by the pressure gauge sensor.

These measured values and calculated values are substituted into the above-mentioned relational expressions in the above-described determination device and solved, and the refrigerant charging rate and the connection pipe length rate are calculated. The refrigerant charging amount is determined from the refrigerant charging rate.

As described above, the influence of the connection pipe length ratio is taken into account, and the amount of refrigerant to be charged is accurately and quantitatively determined.

〔Example〕

FIG. 1 is a system diagram of a refrigerator showing an embodiment of a refrigerant charging amount determination method of the present invention. In the figure, the configuration and operation of the portions denoted by reference numerals 1 to 7 are the same as those of the conventional technology. 11
Is a pressure sensor provided in the discharge pipe 6, 13 is the same temperature sensor, 12 is a pressure sensor provided in the suction pipe 7, 14 is the same temperature sensor, 8 is a temperature sensor provided in the indoor heat exchanger 3, 9 Is a temperature sensor provided in the outdoor heat exchanger 5, 10 is a judging device to which the pressure sensors 11, 12 and the temperature sensors 8, 9, 13, 14 are respectively connected, and 21 is provided in the judging device. A multiplexer, 22 is also an A / D converter, 20 is a controller, 26 is an operation mode circuit connected to the controller 20, and 23, 24, and 25 are display devices connected to the determination device 10. .

FIG. 2 is a cross-sectional view showing a state where the pressure sensor 11 and the temperature sensor 13 provided in the discharge pipe 6 are mounted.

FIG. 3 is a connection diagram of devices connected to the determination device 10 and devices inside the determination device. The high pressure and the discharge temperature in the discharge pipe 6 are measured at the same place by the pressure sensor 11 and the temperature sensor 13. Similarly, the low pressure and the suction temperature in the suction pipe 7 are measured by the pressure sensor 12 and the temperature sensor 14 at the same place. The indoor temperature is measured by the temperature sensor 8, and the outdoor temperature is measured by the temperature sensor 9. Above pressure sensor
The measurement values measured by the temperature sensors 11, 12, and the temperature sensors 8, 9, 13, 14 are input to the determination device 10, and are sent out to the A / D conversion circuit 22 one by one by the multiplexer 21 in the determination device 10, and sequentially. The measured value is converted from an analog value to a digital value and input to the controller 20.

FIG. 4 is a diagram showing a relationship between a pipe length ratio and a discharge superheat degree when a general refrigerator is operated while changing a load applied to the refrigerator to large, medium, or small. As a parameter, the refrigerant charging rate is changed to 80,100,120%. The pipe length ratio on the horizontal axis indicates a range of 100 to 400%. That is, as shown in FIG. 9, when the connection pipe length becomes longer, the suction pressure loss increases, so that the pressure (suction pressure) decreases. As a result, the capacity of the compressor 1 decreases, and the heat exchange capacity of the evaporator (the indoor heat exchanger 3 during cooling in FIG. 1) decreases.

However, when the throttle 4 is a fixed throttle mechanism such as a capillary tube, the flow rate does not decrease with the decrease in the heat exchange capacity, and the flow rate tends to be excessive. For this reason, the degree of suction superheat is reduced, so that a so-called “liquid back” state is achieved, and the degree of discharge superheat is also reduced.

FIG. 4 shows the above state. As shown in FIG. 4, when the same load and the same filling amount are used, the discharge superheat degree decreases as the connection pipe length increases. FIG.
FIG. 4 is a diagram showing a relationship between a pipe length ratio and a suction superheat degree under similar operating conditions. 4 and 5 are represented by a regression equation as follows.

Refrigerant sealing ratio = a ₀ + a ₁ × suction superheat + a ₂ × discharge superheat + a ₃
× indoor temperature + a ₄ × outdoor temperature + a ₅ × connection pipe length ratio ... (1) connected pipe length ratio = b ₀ + b ₁ × suction superheat + b ₂ × discharge superheat +
b ₃ × room temperature + b ₄ × outdoor temperature + b coefficient of ₅ × refrigerant encapsulation efficiency ... (2) where _{a 0 ~a 5, b 0 ~b} 5 are sought in advance. Equations (1) and (2) determined in this way are shown in FIG.
It is stored in the controller 20 shown in FIG.

FIG. 6 shows measurement of indoor / outdoor temperature, calculation of suction superheat,
It is a flowchart which shows the order of calculation of a discharge superheat degree.
Each of the above values obtained by this means is substituted into the regression equations (1) and (2) and arranged as follows.

Refrigerant sealing ratio = a ₁ '× connection pipe length ratio + a _0' ...... (3) connected pipe length ratio = b ₁ '× refrigerant encapsulation rate + b _0' ...... (4) which is capable of solving the simultaneous equations Things,
This solution is obtained in the controller 20, and the refrigerant charging rate is calculated. In accordance with the refrigerant charging rate calculated in this way, the display 23 is operated at the time of low charge, the display 24 at the time of proper charge, and the display 25 at the time of overcharge.

By the method described in detail above, it is possible to accurately determine the amount of the refrigerant sealed in the refrigerator.

[Effects of the Invention] In the method of the present invention for determining the amount of refrigerant charged in a refrigerator,
A relational expression between the indoor temperature, the outdoor temperature, the suction superheat degree and the discharge superheat degree, the refrigerant charging rate and the connection pipe length ratio is determined in advance, and the measured values of the indoor temperature and the outdoor temperature, and the suction superheat degree and the discharge superheat degree From the calculated values, the refrigerant charging rate and the connection pipe length ratio are calculated, and the refrigerant charging rate is determined from the refrigerant charging rate.Therefore, the influence of the connection pipe length ratio is taken into account, and the refrigerant charging rate can be accurately and quantitatively determined. It can be carried out. This can prevent the compressor from being damaged due to overcharge, low charge, and the like, and can appropriately charge the refrigerant amount even when the refrigerator is installed on site.

[Brief description of the drawings]

FIG. 1 is a system diagram of a refrigerator showing one embodiment of the method of the present invention, FIG. 2 is a sectional view showing a mounting state of a pressure sensor and a temperature sensor provided on a discharge pipe, and FIG. FIG. 4 is a connection diagram of the connection pipe length ratio and the discharge superheat degree, FIG. 5 is a connection diagram of the connection pipe length ratio and the suction superheat degree, FIG. FIG. 7 is a flowchart of temperature measurement and superheat degree calculation. FIG. 7 is a system diagram of a refrigerator showing a conventional method of determining the amount of charged refrigerant. FIG. 8 is a Mollier diagram in a refrigeration cycle when the amount of refrigerant is changed. FIG. 9 is a relational diagram between the enthalpy and the pressure on the Mollier diagram when the connection pipe length is changed. 1 ... compressor, 2 ... 4-way valve, 3 ... indoor heat exchanger, 4
... throttle, 5 ... outdoor heat exchanger, 6 ... discharge pipe, 7 ...
... Suction pipe, 8 ... Temperature sensor, 9 ... Temperature sensor, 10
…… Judgment device, 11 …… Pressure sensor, 12 …… Pressure sensor,
13 temperature sensor, 14 temperature sensor, 20 controller, 21 multiplexer, 22 A / D converter, 23
... Display unit, 24 ... Display unit, 25 ... Display unit, 26 ... Operation mode circuit.

Claims (1)

(57) [Claims] 1. A relational expression between an indoor temperature, an outdoor temperature, a suction superheat degree and a discharge superheat degree, a refrigerant charging rate and a connection pipe length ratio is determined in advance, and measured values of the indoor temperature and the outdoor temperature are determined.
A refrigerant charging rate and a connection pipe length ratio are calculated from calculated values of the suction superheat degree and the discharge superheat degree, and the refrigerant charging rate is determined from the refrigerant charging rate.