JP2006308230A - Refrigerating cycle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle control device capable of continuing refrigerating cycle operation and maintaining air-conditioning performance, disusing on-off control of a compressor by a high pressure cutoff switch at the suction temperature rise of a condenser. <P>SOLUTION: The refrigerating cycle control device is provided with a pressure sensor 9 for detecting high pressure of a refrigerant in a refrigerating cycle; level sensors 7, 8 for detecting the amount of liquid refrigerant 10 in an accumulator 5; and a control device 6 for controlling the valve opening of an electronic expansion valve 3. When the high pressure in the cycle becomes a predetermined value or higher, the expansion valve 3 is forcibly opened by the control device 6 so that the amount of liquid refrigerant in the accumulator 5 maintains a high liquid level H. The amount of refrigerant circulating in the refrigerating cycle is thereby reduced to lower the high pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle control device capable of preventing a high pressure cut due to a rise in the suction temperature of a condenser in a refrigeration cycle, continuing a refrigeration cycle operation and maintaining cooling performance.

  If the high pressure in the refrigeration cycle, that is, the condensing pressure of the refrigerant becomes abnormally high while the air conditioner is in operation, it may cause the equipment to malfunction or be damaged. As a control when the pressure in the refrigeration cycle rises abnormally, the conventional technique generally uses on / off control of the compressor by a high-pressure cut switch. There was a problem that the cooling feeling deteriorated due to the fluctuation.

  As a method of preventing such on / off control of the compressor, when the evaporator falls into an excessive capacity state (when the pressure in the refrigeration cycle abnormally increases), the opening control of the electric expansion valve is overheated. Patent Document 1 proposes a method of changing from constant control to control that maintains the high pressure of the compressor at an appropriate value.

Japanese Examined Patent Publication No. 6-50197

  However, the above method results in the expansion valve being throttled and the degree of superheat at the evaporator outlet being increased, leading to an increase in the temperature of the refrigerant gas sucked into the compressor and a decrease in the amount of refrigerant gas flowing into the compressor. There is a problem that the body is overheated and reliability is lowered.

  The present invention has been made in view of the above problems, and its object is to eliminate the compressor on-off control by the high-pressure cut switch when the suction temperature of the condenser in the refrigeration cycle rises, and to operate the refrigeration cycle. A refrigeration cycle control device that can continue and maintain cooling performance.

The present invention provides a refrigeration cycle control device according to each of the claims as means for solving the problems.
The refrigeration cycle control device according to claim 1 includes a pressure detection means 9 for detecting the high pressure of the refrigerant in the refrigeration cycle, and a refrigerant circulation amount control means 6, 7, 8 for controlling the amount of refrigerant circulating in the refrigeration cycle. When the high pressure of the refrigerant in the refrigeration cycle detected by the pressure detection means 9 exceeds a predetermined value, the refrigerant circulation amount control means 6, 7, 8 circulate in the refrigeration cycle. Control is performed so that the amount of the refrigerant is reduced. As a result, the refrigerant becomes deficient in operation and the cooling capacity is reduced, but the fluctuation of the cooling air blowing temperature is small, and the cooling feeling is greatly improved. Further, since the refrigerant having a superheat degree of 0 ° C. is sucked into the compressor 1, the compressor 1 can be prevented from being overheated and the reliability is improved.

In the control device according to the second aspect, the refrigerant circulation amount control means 6, 7, and 8 forcibly set the liquid amount detection means 7 and 8 for detecting the amount of liquid refrigerant in the accumulator and the valve opening degree of the decompression means. Until the high-pressure pressure of the refrigerant in the refrigeration cycle exceeds a predetermined value, the liquid amount detection means 7 and 8 detect that the liquid refrigerant in the accumulator has reached a predetermined amount. The decompression means 3 and 32 are forcibly opened by the opening means 6, whereby the liquid level in the accumulator 5 is raised and a certain amount of liquid refrigerant is held in the accumulator 5, so that the inside of the refrigeration cycle It is possible to reduce the amount of refrigerant circulating.
In the control device according to claim 3, the refrigerant circulation amount control means 6 is an opening means 6 for forcibly opening the valve opening degree of the decompression means, and the high pressure of the refrigerant detected by the pressure detection means 9 is The pressure reducing means 3 and 32 are forcibly opened until the second predetermined value is reached when a predetermined value of 1 is reached, thereby increasing the liquid refrigerant in the accumulator, The amount of refrigerant circulating inside can be reduced.

The control device according to claim 4 uses the electronic expansion valve 3 as a pressure reducing means, and controls the valve opening degree of the electronic expansion valve 3 to adjust the amount of refrigerant circulating in the refrigeration cycle. It is something that can be done.
The control device according to claim 5 uses a combination configuration of a temperature-sensitive expansion valve 31 and a solenoid valve 32 arranged in parallel as decompression means, and thereby opens and closes the solenoid valve 32 to open and close the refrigeration cycle. The amount of refrigerant circulating inside can be increased or decreased.

  Hereinafter, a refrigeration cycle control apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a refrigeration cycle control device according to a first embodiment of the present invention. The refrigeration cycle of the present embodiment includes a compressor (compressor) 1, a condenser (condenser) 2, an electronic expansion valve 3 as a decompression means, an evaporator (evaporator) 4, and an accumulator 5, which are sequentially connected by piping. It is connected.

  This refrigeration cycle operates as follows. First, a highly compressed refrigerant (high pressure, high temperature gas refrigerant) is discharged from the compressor 1 and introduced into the condenser 2. The refrigerant is condensed in the condenser 2 to be in a liquid phase (high temperature, high pressure liquid refrigerant), and then adiabatically expanded in the electronic expansion valve 3 to be a gas-liquid two phase refrigerant (low temperature, low pressure refrigerant). It becomes. This gas-liquid two-phase refrigerant is then introduced into the evaporator 4 and vaporized to become a gas refrigerant. At this time, the air is cooled by the evaporator 4 and supplied to the cooling in the passenger compartment. Further, the gas refrigerant discharged from the evaporator 4 enters the accumulator 5 where it is temporarily stored. Next, only the gas refrigerant is sucked into the compressor 1 from the accumulator 5.

  Further, a pressure sensor 9 which is a pressure detecting means for detecting the high pressure of the gas refrigerant discharged from the compressor 1 is disposed on the outlet side pipe of the compressor 1. Further, the accumulator 5 is provided with a high liquid level (H) level sensor 7 and a low liquid level (L) level sensor 8 which are liquid amount detecting means for detecting the amount of the liquid refrigerant 10. Information on the high-pressure pressure of the refrigerant detected by the pressure sensor 9 and the amount of the liquid refrigerant 10 in the accumulator 5 detected by the level sensors 7 and 8 are input to the control device 6, and the control device 6 is based on this information. The valve opening degree of the electronic expansion valve 3 is controlled. In this case, the level sensors 7 and 8 and the control device 6 correspond to refrigerant circulation amount control means for controlling the amount of refrigerant circulating in the refrigeration cycle.

Next, the operation of the refrigeration cycle control apparatus having the above configuration will be described.
(1) During normal operation During normal operation, the opening degree of the electronic expansion valve 3 is controlled by the control device 6 so that the liquid refrigerant 10 in the accumulator 5 is at the position of the low liquid level (L) level sensor 8. Control. In this way, by controlling the refrigeration cycle so that the liquid refrigerant 10 is always in the accumulator 5, the degree of superheat becomes 0 ° C. in the evaporator 4, and the evaporator 4 that secures the degree of superheat above 0 ° C. Cooling performance is large and efficient operation is possible.

(2) When the high pressure rises When the high pressure in the refrigeration cycle detected by the pressure sensor 9 exceeds a predetermined value, the liquid refrigerant 10 in the accumulator 5 is raised to the position of the high liquid level (H) level sensor 7. When the electronic expansion valve is temporarily and forcibly opened by the control device 6 to increase the amount of liquid refrigerant in the accumulator 5 and the liquid refrigerant 10 reaches the position of the high liquid level (H) level sensor 7. Thus, the electronic expansion valve 3 is controlled by the control device 6 so as to maintain this position.

In this way, by holding a certain amount of the liquid refrigerant 10 in the accumulator 5 at the position of the high liquid level (H) level sensor 7, the circulating refrigerant in the refrigeration cycle becomes insufficient, resulting in a refrigerant shortage operation. Thereby, the high pressure in the refrigeration cycle decreases.
Although the cooling capacity is reduced due to the refrigerant shortage operation of the refrigeration cycle, the fluctuation of the cold air blowing temperature is small, and the cooling feeling is greatly improved compared to the temperature fluctuation of the cold air due to the on / off operation of the compressor 1. Is done. In addition, since the refrigerant having a superheat degree of 0 ° C. is sucked into the compressor 1 by the compressor 1, the compressor 1 can be prevented from being overheated and the reliability is improved.

FIG. 2 is a diagram showing the refrigeration cycle in the present embodiment on a Mollier diagram. In FIG. 2, the horizontal axis represents enthalpy i (kcal / kg), and the vertical axis represents absolute pressure P (kg / cm ² abs). The refrigeration cycle indicated by the solid line represents a refrigeration cycle during normal operation in a state where the liquid refrigerant 10 in the accumulator 5 is at the position of the low liquid level (L) level sensor 8, and an operation with a large cooling capacity is performed. It shows that. Also, the refrigeration cycle indicated by the dotted line represents a refrigeration cycle for operation when the liquid refrigerant 10 in the accumulator 5 is at a high liquid level (H) level sensor 7 during high pressure rise, and has a low cooling capacity and a high pressure. Indicates that the operation has been reduced.

  FIG. 3 is a diagram illustrating a refrigeration cycle control device according to another embodiment of the present invention. In the embodiment described above, the electronic expansion valve 3 is used as the pressure reducing means. However, in this embodiment, the pressure expansion means is composed of a combination of the temperature-sensitive expansion valve 31 and the solenoid valve 32 arranged in parallel. ing. The rest of the configuration is the same as in the previous embodiment. Therefore, in this other embodiment, the level sensors 7 and 8 and the control device 6 correspond to refrigerant circulation amount control means for controlling the amount of refrigerant circulating in the refrigeration cycle.

In this embodiment, during normal operation, the electromagnetic valve 32 is closed by the control device 6 so that the liquid refrigerant 10 in the accumulator 5 is at the position of the low liquid level (L) level sensor 8, and the condenser 2 is The condensed high-temperature and high-pressure liquid refrigerant 10 expands through the temperature-sensitive expansion valve 31 and is introduced into the evaporator 4 as a gas-liquid two-phase refrigerant.
On the other hand, when the high pressure detected by the pressure sensor 9 is equal to or higher than a predetermined value, the electromagnetic valve is forcibly opened by the control device 6 and the liquid refrigerant condensed by the condenser 2 After passing through both the valve 32 and the temperature-sensitive expansion valve 31, the refrigerant is introduced into the evaporator 4, and the liquid refrigerant 10 in the accumulator 5 increases to increase the high liquid level (H) level sensor 7. Try to maintain the position. Thereby, the circulating refrigerant in the refrigeration cycle runs short, and the refrigerant runs short, and the high pressure in the refrigeration cycle decreases.

  As described above, in the present invention, during normal operation, the liquid level of the accumulator 5 is kept low, and when the high pressure in the refrigeration cycle rises above a predetermined value, the valve opening of the decompression means is opened, and the accumulator The level of the liquid in the tank 5 is raised, the liquid refrigerant 10 is held in a certain amount in the accumulator 5, and the amount of refrigerant circulating in the refrigeration cycle is reduced. Thereby, a refrigerating cycle will be in a refrigerant gas shortage state, and a high pressure will fall. Further, since the refrigerant having a superheat degree of 0 ° C. is always sucked into the compressor 1 by the accumulator 5, the compressor 1 can be prevented from being overheated and the reliability can be prevented from being lowered.

  In the above-described embodiment, the pressure sensor 9 and the level sensors 7 and 8 are used, and the electronic expansion valve 3 or the electromagnetic valve 32 which is a decompression unit by the control device 6 based on the information detected by them. The amount of refrigerant circulating in the refrigeration cycle is controlled by controlling the level, but the level sensors 7 and 8 are removed and only the pressure sensor 9 is used to control the amount of refrigerant circulating in the refrigeration cycle. You can also. That is, when the high pressure in the refrigeration cycle detected by the pressure sensor 9 exceeds the first predetermined value, the controller 6 forcibly opens the valve opening of the decompression means, and this high pressure is This state may be continued until a predetermined value of 2 or less is reached. In this case, the control device 6 is a refrigerant circulation amount control means and is also an opening means.

It is a figure explaining the refrigerating-cycle control apparatus of embodiment of this invention. It is a figure explaining the refrigerating cycle of the refrigerating-cycle control apparatus of this invention on a Mollier diagram. It is a figure explaining the refrigerating-cycle control apparatus of another embodiment of this invention.

Explanation of symbols

1 Compressor 2 Condenser 3 Electronic expansion valve (pressure reduction means)
31 Temperature-sensitive expansion valve 32 Solenoid valve 4 Evaporator 5 Accumulator 6 Control device (refrigerant circulation amount control means, opening means)
7 High liquid level (H) level sensor (Liquid level detection means)
8 Low liquid level (L) level sensor (Liquid level detection means)
9 Pressure sensor (pressure detection means)

Claims (5)

Compressor (1) for compressing gas refrigerant, condenser (2) for condensing compressed gas refrigerant, decompression means (3, 31, 32) for decompressing the condensed refrigerant, evaporation for evaporating the decompressed refrigerant A refrigeration cycle in which a vessel (4) and an accumulator (5) are sequentially connected,
Pressure detecting means (9) for detecting the high pressure of the refrigerant in the refrigeration cycle;
Refrigerant circulation amount control means (6, 7, 8) for controlling the amount of refrigerant circulating in the refrigeration cycle;
And when the high pressure of the refrigerant detected by the pressure detection means (9) exceeds a predetermined value, the refrigerant circulation amount control means (6, 7, 8) A refrigeration cycle control device that controls the amount of refrigerant circulating through the refrigerant to be small. The refrigerant circulation amount control means (6, 7, 8)
Liquid amount detection means (7, 8) for detecting the amount of liquid refrigerant in the accumulator;
Opening means (6) for forcibly opening the valve opening of the decompression means;
When the high pressure of the refrigerant in the refrigeration cycle becomes equal to or higher than a predetermined value, the liquid amount detecting means (7, 8) detects that the liquid refrigerant in the accumulator has reached a predetermined amount. The refrigeration cycle control device according to claim 1, wherein the decompression means (3, 32) is forcibly opened by the opening means (6).   The refrigerant circulation amount control means (6) is an opening means (6) for forcibly opening the valve opening of the decompression means, and the high pressure detected by the pressure detection means (9) is a first predetermined value. 2. The refrigeration cycle control device according to claim 1, wherein when the pressure exceeds a value, the decompression means (3, 32) is forcibly opened by the opening means until a second predetermined value is reached.   The refrigeration cycle control device according to claim 1, 2 or 3, wherein the decompression means is an electronic expansion valve (3).   The refrigeration cycle according to claim 1, 2 or 3, wherein the pressure reducing means is composed of a combination of a temperature-sensitive expansion valve (31) and a solenoid valve (32) arranged in parallel. Control device.

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