JP3813228B2 - Refrigeration equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration apparatus that is equipped with a full-liquid condenser and controls the opening degree of an expansion valve so that the liquid level of the condenser is constant by a high-pressure float.
[0002]
[Prior art]
FIG. 5 is a configuration diagram of a conventional refrigeration apparatus. The refrigeration cycle includes a compressor 1 that compresses a refrigerant gas, a full-liquid condenser 2 that condenses and liquefies the compressed refrigerant gas, and a condensed refrigerant liquid. An expansion valve 3 for lowering the pressure of the refrigerant and an evaporator 4 for evaporating the refrigerant liquid to obtain a refrigeration output. A discharge pipe 6 is provided between the compressor 1 and the full liquid condenser 2, and main liquid pipes 7 a and b are provided between the full liquid condenser 2 and the expansion valve 3 and between the expansion valve 3 and the evaporator 4. A suction pipe 8 is disposed between the evaporator 4 and the compressor 1.
Reference numeral 5 denotes a high pressure float having a needle portion 5n. The high pressure float 5 and the full liquid condenser 2 are connected by a gas side pipe 9a and a liquid side pipe 9b, and the high pressure float 5 and the expansion valve 3 are connected. Connected by a pipe 10.
[0003]
Next, the operation of the refrigeration apparatus will be described.
The refrigerant gas discharged from the compressor 1 is condensed and liquefied by the full-liquid condenser 2 through the discharge pipe 6, and the condensed refrigerant liquid is squeezed and expanded by the expansion valve 3 through the main liquid pipe 7a. It is supplied to the evaporator 4 through the liquid pipe 7b. The refrigerant liquid evaporates in the evaporator 4 and becomes gas, and is sucked into the compressor 1 through the suction pipe 8.
A part of the refrigerant liquid of the full-liquid condenser 2 passes through the liquid side pipe 9b, the high-pressure float 5, and the pipe 10 and controls the opening degree of the expansion valve 3, and then merges into the pipe 7b. The opening degree of the expansion valve 3 is controlled by the pressure of the refrigerant in the pipe 10 decompressed by the needle portion 5n inside the high-pressure float 5 and moves in the opening direction as the pressure in the pipe 10 is higher, and in the closing direction as the pressure is lower. .
The needle portion 5n inside the high-pressure float 5 operates in the opening direction as the liquid level of the full liquid condenser 2 increases, and the pressure in the pipe 10 increases, and operates in the closing direction as the liquid level decreases. The pressure of becomes low. In addition, the difference in the liquid level height of the condenser 2 in which the needle part of the high-pressure float 5 is fully closed and fully opened is about 10 mm.
As a result, the opening degree of the expansion valve 3 is controlled by the high-pressure float 5 so that the liquid level of the condenser 2 is substantially constant (control width 10 mm).
[0004]
[Problems to be solved by the invention]
Since the conventional refrigeration apparatus is configured as described above, when the amount of refrigerant gas discharged from the compressor 1 is drastically reduced by the capacity control of the compressor 1 or the like, the liquid level of the full liquid condenser 2 is increased. Even if the needle portion 5n of the high pressure float 5 operates in the closing direction due to the decrease in the pressure, the pressure in the pipe 10 does not decrease until the refrigerant liquid in the pipe 10 merges into the pipe 7b through the expansion valve 3, so that the expansion valve opening degree , The liquid level of the condenser 2 is lowered, and the liquid level of the evaporator 4 is raised by that amount, so that the compressor 1 sucks the refrigerant liquid and the liquid compression operation occurs.
[0005]
The present invention has been made to solve the above-described problems, and an object thereof is to prevent a liquid back (liquid compression) operation of a compressor during operation of a refrigeration unit.
[0006]
[Means for Solving the Problems]
In the refrigeration apparatus according to the first aspect of the present invention, a part of the refrigerant liquid in the condenser 2 is pressure-adjusted according to the liquid level height of the condenser 2 and sent to the expansion valve 3. In addition to the liquid level control means (high pressure float 5) to be controlled and the first detection means (float switch 12a) for detecting the lower limit value of the liquid level of the condenser 2, the lower limit position of the liquid level. A second detection means (float switch 12b) for detecting a higher predetermined position is provided, and when the first detection means 12a detects the lower limit value of the liquid level, the refrigerant to the expansion valve 3 in the liquid level control means The liquid supply is stopped and the expansion valve 3 is fully closed. When the second detection means 12b detects a predetermined position, the supply stop of the refrigerant liquid to the expansion valve 3 is released.
[0007]
The invention of claim 2 is provided with circuit piping 15a, b, 17a, b for returning the refrigerant in the evaporator 4 to the condenser 2 when the liquid level of the condenser 2 is lowered while the operation of the refrigeration apparatus is stopped. did.
[0008]
According to a third aspect of the present invention, the circuit pipes 15a, b, 17a, b are about 1/3 of the main liquid pipes 7a, b between the condenser 2 and the evaporator 4.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
1 is a block diagram showing a refrigeration apparatus according to Embodiment 1 of the present invention.
In the figure, the refrigeration cycle includes a compressor 1 that compresses refrigerant gas, a full-liquid condenser 2 that condenses and liquefies the compressed refrigerant gas, an expansion valve 3 that reduces the pressure of the condensed refrigerant liquid, and a refrigerant It consists of an evaporator 4 that evaporates the liquid to obtain a refrigeration output, 5 is a high-pressure float having a needle portion 5n, 6 is a discharge pipe, 7a and b are main liquid pipes, 8 is a suction pipe, and 9a and b are A gas side pipe and a liquid side pipe 10 for connecting the high pressure float 5 and the full liquid condenser 2 are pipes for connecting the high pressure float 5 and the expansion valve 3. The above components are the same as those of the conventional example (FIG. 5).
The component parts that characterize the first embodiment are 11, 12a, b, 13a, b, 11 is an electromagnetic valve provided in the pipe 10, and 12a sets a lower limit value of the liquid level of the condenser 2. The float switch 12b is a float switch for setting the liquid level height of the condenser for finishing the control, and the set liquid level height is higher than the set liquid level height of the float switch 12a. Reference numerals 13a and 13b are pipes connecting the condenser 2 and the float switches 12a and 12b.
[0010]
Next, the operation of the above apparatus will be described.
The normal operation is the same as in the conventional example. The refrigerant gas discharged from the compressor 1 passes through the discharge pipe 6 and is condensed and liquefied by the full-liquid condenser 2, and the condensed refrigerant liquid passes through the main liquid pipe 7a. After being throttled and expanded by the passage expansion valve 3, it is supplied to the evaporator 4 through the main liquid pipe 7 b. Then, it evaporates in the evaporator 4 and becomes gas, and is sucked into the compressor 1 through the suction pipe 8. Further, a part of the refrigerant liquid of the full liquid condenser 2 passes through the liquid side pipe 9b, the high pressure float 5, and the pipe 10 and controls the opening degree of the expansion valve 3, and then merges into the pipe 7b. The opening degree of the expansion valve 3 is controlled by the pressure of the refrigerant in the pipe 10 decompressed by the needle portion 5n inside the high-pressure float 5 and moves in the opening direction as the pressure in the pipe 10 is higher, and in the closing direction as the pressure is lower. . Here, the needle portion 5n inside the high-pressure float 5 operates in the opening direction as the liquid level of the full liquid condenser 2 increases, and operates in the closing direction as the pressure of the pipe 10 increases and the liquid level decreases. The pressure of the pipe 10 becomes low.
[0011]
In Embodiment 1, when the liquid level of the condenser 2 becomes lower than the float switch 12a during the normal unit operation as described above, the solenoid valve 11 is closed and the expansion valve 3 is immediately turned on. Fully closed to raise the liquid level of the condenser 2. When the liquid level of the condenser 2 becomes higher than the float switch 12b, the electromagnetic valve 6 is opened, the above control is terminated, and the normal unit operation is performed.
The above operation will be described with reference to the flowchart of FIG. 2. When the refrigeration unit is operating with the expansion valve control by the normal high pressure float 5 (S100), the ON / OFF state of the float switch 12a is determined (S101), and the float switch 12a. Is turned off due to a drop in the liquid level of the condenser 2, the electromagnetic valve 11 is closed (S102), and the expansion valve 3 is fully closed.
When the liquid level of the condenser 2 rises and the float switch 12b is turned on (S103), the electromagnetic valve 11 is opened (S104), and the expansion valve control by the normal high-pressure float 5 is performed.
Here, the upper limit and the lower limit of the liquid level height of the condenser 2 set by the float switch 12a and the float switch 12b are set in a range in which the heat transfer characteristics of the evaporator 4 and the condenser 2 are not deteriorated. This is because if the heat transfer characteristic of the condenser 2 decreases, an abnormal increase in high pressure is caused, and if the heat transfer characteristic of the evaporator 4 decreases, an abnormal decrease in low pressure occurs.
[0012]
Embodiment 2. FIG.
The second embodiment is for increasing the reliability of preventing liquid back immediately after the start of the refrigeration unit in the first embodiment.
That is, when the liquid level of the condenser 2 has already dropped and the liquid level of the evaporator 4 has risen before the refrigeration unit is started, the refrigerant liquid of the evaporator 4 is returned to the condenser 2 and the liquid back immediately after the unit is started. Prevent driving.
FIG. 3 is a configuration diagram of the refrigeration apparatus according to the second embodiment. Components 1 to 13 are the same as those in the first embodiment.
The component parts that characterize this embodiment are 14, 15a, b, 16, 17a, b, 14 is an electromagnetic valve for returning the refrigerant of the evaporator 4 to the condenser 2, and 15a, b are the condenser 2. And a liquid side pipe (diameter of about 15.8 mm) for connecting the evaporator 4 and the evaporator 4 via a solenoid valve 14, 16 is a solenoid valve for equalizing the internal pressure of the condenser 2 and the evaporator 4, 17a and b are condensed This is a gas side pipe (diameter of about 15.8 mm) connecting the vessel 2 and the evaporator 4 via the electromagnetic valve 16.
The main liquid pipes 7a and 7b have a diameter of about 50.8 mm. However, since it is not necessary to immediately return the refrigerant liquid to the condenser 2, the liquid side pipe and the gas side pipe may be about 1/3 of that.
The positional relationship between the evaporator 4 and the condenser 2 is such that the evaporator 4 is on the upper side and the condenser 2 is on the lower side.
[0013]
Next, the operation of the above apparatus will be described.
Normal driving operation is the same as before.
In this embodiment, when the unit is stopped, when the liquid level of the condenser 2 decreases and becomes lower than the float switch 12a, the electromagnetic valve 14 and the electromagnetic valve 16 are opened, and the inside of the condenser 2 and the evaporator 4 is opened. Make equal pressure. Since the evaporator 4 is located higher than the condenser 2, the refrigerant in the evaporator 4 falls to the condenser 2 by its own weight.
When the refrigerant in the evaporator 4 becomes too low, there is a problem that the low pressure is too low immediately after starting the unit. Therefore, when the liquid level of the condenser 2 reaches the height of the float switch 12b, the solenoid valve 14 and the solenoid valve 16 are turned on. Control is terminated as closed.
This flowchart is shown in FIG.
That is, when the liquid level of the condenser 2 is lowered and the float switch 12a is turned off (S201) while the unit operation is stopped (S200), the solenoid valve 14 and the solenoid valve 16 are opened (S202), and the refrigerant evaporates by its own weight. The refrigerant in the condenser 4 is dropped into the condenser 2 and the liquid level of the condenser 2 is raised.
When the liquid level of the condenser 2 becomes higher than the float switch 12b and the switch is turned on (S203), the solenoid valve 14 and the solenoid valve 16 are closed (S204), the control is terminated, and the unit is brought into a normal stop state.
[0014]
【The invention's effect】
As described above, according to the invention of the first aspect, it is possible to prevent the liquid compression operation (liquid back operation) of the compressor accompanying the liquid level drop during the operation of the refrigeration unit.
[0015]
According to the invention of claim 2 , the liquid compression operation (liquid back operation) immediately after the start of the refrigeration unit can be prevented, and the reliability is improved.
[0016]
Furthermore, according to the invention of claim 3 , it is possible to save space for piping installation.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a refrigeration apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a flowchart according to the first embodiment.
3 is a configuration diagram showing a refrigeration apparatus according to Embodiment 2. FIG.
FIG. 4 is a flowchart according to the second embodiment.
FIG. 5 is a configuration diagram of a conventional refrigerator.
[Explanation of symbols]
1 compressor, 2 condenser, 3 expansion valve, 4 evaporator, 5 high pressure float,
5n Needle part, 6 Discharge piping, 7a, b Main liquid piping, 8 Suction piping,
9a, b piping, 10 piping, 11 solenoid valve, 12a, b float switch,
13a, b piping, 14 solenoid valve, 15a, b piping, 16 solenoid valve, 17a piping,
18a piping.

Claims (3)

A refrigeration apparatus including a compressor, a condenser, an expansion valve, and an evaporator, wherein a part of the refrigerant liquid in the condenser is pressure-adjusted according to the liquid level of the condenser and sent to the expansion valve. Liquid level control means for controlling the opening of the expansion valve, first detection means for detecting a lower limit value of the liquid level of the condenser, and higher than a lower limit position of the liquid level of the condenser When the second detection means for detecting the predetermined position and the first detection means detect the lower limit value of the liquid level height, the supply of the refrigerant liquid to the expansion valve in the liquid level height control means is stopped and the expansion valve is turned off. A refrigeration apparatus comprising a means for closing and releasing the suspension of the supply of the refrigerant liquid to the expansion valve when the second detection means detects the predetermined position. 2. The refrigeration apparatus according to claim 1, further comprising a circuit pipe for returning the refrigerant in the evaporator to the condenser when the liquid level of the condenser is lowered while the operation of the refrigeration apparatus is stopped. The refrigeration apparatus according to claim 2, wherein the diameter of the circuit pipe is about 1/3 of the diameter of the main liquid pipe between the condenser and the evaporator.

Images