JPH06100387B2 - Refrigeration cycle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refrigeration cycle applied to an air conditioner.

[Prior Art] FIG. 5 is a view showing a conventional refrigeration cycle (see Japanese Patent Publication No. 39-585). In FIG. 5, the refrigerant is compressor 101 → condenser 102 → capillary tube 103 → evaporator 104. → compressor 1
It flows with 01. The suction pipe 108 of the compressor 101 is connected to the suction pipe 108.
A liquid reservoir 105 is arranged so as to exchange heat with. The intermediate point 109 between the liquid reservoir 105 and the capillary tube 103 is a pipe 106.
Connected by. The liquid reservoir 105 is in equilibrium with the refrigeration cycle and does not change when the amount of the refrigerant in the refrigeration cycle is appropriately maintained. The load on the refrigeration cycle fluctuates, and the amount of the refrigerant becomes insufficient or insufficient with respect to the appropriate amount, and the temperature of the suction pipe 108 rises or falls, whereby the sump 105 The internal pressure is set higher or lower than the intermediate point 109 of the capillary tube 103 to adjust the amount of the refrigerant in the refrigeration cycle according to the temperature state of the suction pipe 108 of the compressor 101. In this refrigeration cycle, when proper operation is performed, for example, when the load on the side of the evaporator 104 increases due to a rise in the temperature of the medium for heat exchange, etc., the evaporator 104
As the temperature of the suction pipe 108 rises, the temperature inside the liquid reservoir 105 rises, and the pressure inside the liquid reservoir 105> the connection point 109 between the pipe 106 and the capillary tube 103.
And the refrigerant is discharged from the liquid reservoir 105 onto the main refrigeration cycle. As a result, the amount of the refrigerant in the refrigeration cycle increases, but the capillary tube 103 that performs expansion is restricted.
Because of the fixed throttle, even if the amount of refrigerant in the refrigeration cycle increases, refrigerant eventually accumulates inside the condenser 102,
The high pressure increased, the power required for the compressor 101 increased, and efficient operation was not achieved.

[Problems to be Solved by the Invention] In the conventional refrigeration cycle, as described above, the capillary tube 103 is fixed even if the refrigerant is adjusted by the liquid reservoir 105 in order to adjust the degree of superheat of the suction pipe 108. Since it is a throttle, for example, when the load on the evaporator 104 increases, even if the refrigerant is discharged from the liquid reservoir 105 during the cycle and the superheat degree in the suction pipe 108 is adjusted, the refrigerant accumulates inside the condenser 102. As a result, the high pressure increased, and efficient operation was not achieved.

The present invention provides a refrigeration cycle that solves the above conventional problems, optimizes the amount of refrigerant in the refrigeration cycle, prevents high-pressure pressure rise and flash gas generation, and enables efficient operation. With the goal.

[Means for Solving Problems] A refrigeration cycle according to the present invention is a refrigeration cycle including a compressor, a condenser, an electronic expansion valve, and an evaporator, and has a condensing pressure saturation temperature of a refrigerant and expansion expansion by the electronic expansion valve. Before the temperature of the condensed refrigerant is detected to detect the degree of supercooling of the refrigerant, and the control means for controlling the opening degree of the electronic expansion valve based on the degree of supercooling of the refrigerant is provided together with the suction pipe of the compressor. In addition, a refrigerant pipe connecting the electronic expansion valve and the evaporator and a refrigerant liquid reservoir connected through the pipe are provided.
That is, in the present invention, a temperature sensor for detecting the condensation pressure saturation temperature is provided between the compressor and the end of the condenser on the side of the electronic expansion valve, and the electronic expansion valve and the side of the electronic expansion valve of the condenser are arranged. A temperature sensor that detects the temperature of the refrigerant before expansion is placed between the ends, and the control unit detects the degree of supercooling of the refrigerant before expansion by the temperature detected by each of these temperature sensors. , The opening of the electronic expansion valve is controlled, and a liquid reservoir for exchanging heat with the suction pipe of the compressor is provided.
The point between the liquid reservoir, the electronic expansion valve, and the suction pipe at the end of the liquid reservoir on the evaporator side is connected by a pipe.

[Operation] According to the present invention, since the supercooling degree has the above-described configuration, the temperature of the condenser is detected by the temperature sensor, and the temperature before the expansion of the throttle is detected by the temperature sensor. The opening of the electronic expansion valve is controlled by the control unit based on the temperature detected by the sensor, and the degree of superheat is changed by the temperature change in the suction pipe due to the temperature change in the suction pipe due to the temperature change in the suction pipe. By adjusting the amount and the degree of superheat, the amount of the refrigerant in the refrigeration cycle can be optimized, and the high pressure increase and the generation of flash gas can be prevented.

[Embodiment] FIG. 1 is a refrigeration cycle diagram showing an embodiment of the present invention.
Is a compressor, 2 is a condenser, 3 is an electronic expansion valve, 4 is an evaporator,
5 is a liquid reservoir, 6 is a pipe, 7 is a discharge pipe, 8 is a suction pipe,
Reference numeral 9 is a connection point of the pipe, 10 and 11 are temperature sensors, 12 is a control unit, and 13 is a connection point.

In FIG. 1, the refrigerant flows in the order of compressor 1 → condenser 2 → electronic expansion valve 3 → evaporator 4 → compressor 1. A temperature sensor 10 is attached to the condenser 2, and a temperature sensor 11 is attached to the pipe before expansion. The degree of supercooling of the refrigerant before the expansion by the temperature sensors 10 and 11 (condensation pressure saturation temperature of the refrigerant-the temperature of the refrigerant before the expansion, the condensation pressure saturation temperature in this case is the temperature detected by the temperature sensor 10). The temperature of the electronic expansion valve 3 is calculated by the control unit 12, and the opening degree of the electronic expansion valve 3 is set and controlled. A liquid reservoir 5 is arranged in the suction pipe 8 of the compressor 1. Liquid reservoir 5 is pipe 6
Is connected to an intermediate connection point 9 between the electronic expansion valve 3 and the evaporator 4 (the connection point 9 in FIG. 1 is a suction pipe 8 of the electronic expansion valve 3 and the end 13 of the liquid reservoir 5 on the evaporator 4 side). Any intermediate point is fine). The liquid reservoir 5 is in equilibrium with the refrigeration cycle and does not change when the amount of the refrigerant in the refrigeration cycle is properly maintained. The load on the refrigeration cycle fluctuates, and the amount of refrigerant becomes insufficient or excessive with respect to an appropriate amount, and the temperature of the suction pipe 8 rises or falls, so that the pressure inside the liquid reservoir 5 is increased. The amount of the refrigerant in the refrigeration cycle is adjusted according to the temperature state of the suction pipe 8 of the compressor 1 by increasing or decreasing the pressure at the connection point 9,
The superheat degree of the refrigerant sucked into the compressor 1 is adjusted in the same manner as the conventional one. FIG. 3 is a block diagram for explaining the operation of one embodiment of the present invention. In FIG. 3, the respective temperatures are detected by the condensing temperature Tc detecting means 31 and the expansion valve pre-temperature Tv detecting means 32. Depending on the detected temperature, the calculator 33 calculates the supercooling uniformity Sc
(Specifically, Sc = Tc-Tv) is calculated, and the calculated degree of supercooling
Sc and the supercooling degree Scs set by the supercooling degree setting means 34 are compared by the comparing means 35, and the expansion valve opening degree setting means
Set the expansion valve opening with 36 to keep the degree of supercooling appropriate. Fourth
The figure shows a flow chart showing the operation of one embodiment of the present invention, 41 enters the flow for setting the subcooling degree, 42 detects the condensation temperature Tc, 43 detects the temperature Tv before the expansion valve , 44 calculates the supercooling degree Sc based on those temperatures, 45 calculates and sets the opening of the expansion valve based on the calculated subcooling degree, and 46 determines whether the subcooling degree Sc is OK or not. , NO, the above 42 to 45 are repeated, and if YES, return of the flow indicated by 47, that is, the flow exits from this flow.

FIG. 2 shows an embodiment in which the present invention is applied to a heat pump. The refrigerant during cooling operation is the compressor 1 → the four-way switching valve 20 →
The outdoor heat exchanger 2 ′ → the check valve 14 → the electronic expansion valve 3 → the capillary tube 18 → the check valve 17 → the indoor heat exchanger 4 ′ → the four-way switching valve 20 → the compressor 1 flow. Refrigerant during heating operation is compressor 1-> 4-way switching valve 20-> indoor side exchanger 4 '-> check valve 15-> electronic expansion valve 3-> capillary tube 18-> check valve 16-> outdoor heat exchanger 2'-> 4-way switching Flows from valve 20 to compressor 1. The liquid reservoir 5 is connected to the electronic expansion valve 3 and the capillary tube 18 by a pipe 6.
Is connected to the connection point 9 between. (The capillary tube 18 is for adjusting the pressure of the connection point 9 and may be omitted if not necessary. In this case, the connection point 9 of the pipe 6 may be between the electronic expansion valve 3 and the check valve 17.). The operating principle of the liquid reservoir 5 is that the refrigerant flows into and out of the liquid reservoir 5 due to the pressure relationship between the pressure inside the liquid reservoir 5 and the pressure at the connection point 9 as in FIG. The temperature before the expansion is detected by the temperature sensor 11, the condensing temperature is detected by the temperature sensor 10 during cooling operation, and the temperature sensor 19 is detected during heating operation.
To detect each. The control unit 12 calculates the degree of supercooling based on the detected temperature and sets the opening degree of the electronic expansion valve 3. First
In the figure, the condensation pressure saturation temperature is the temperature sensor of the condenser 2.
Although it is detected by 10, it is possible to detect the condensation pressure saturation temperature at any point between the compressor 1 and the condenser 2. Further, the temperature before the expansion is restricted by the condenser 2 and the electronic expansion valve 3.
Any position in the middle of which the temperature of the refrigerant before the expansion can be detected can be used.

[Effects of the Invention] As described in detail above, the present invention has the following effects.

(1) The amount of refrigerant in the refrigeration cycle becomes appropriate by adjusting the degree of superheat of the suction pipe with the liquid reservoir.

(2) Even if the degree of superheat of the suction pipe changes due to the fluctuation of the load on the evaporator side or the condenser side and the amount of the refrigerant in the main refrigeration cycle changes, the electronic expansion valve is controlled, and the refrigerant before expansion is expanded. By adjusting the degree of supercooling, it is possible to prevent the refrigerant from accumulating inside the condenser and the generation of flash gas of the refrigerant before the expansion.

(3) The above problems due to the high pressure rise and the generation of flash gas are eliminated.

(4) Due to the above, an efficient refrigeration cycle can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a diagram showing a configuration of an embodiment when the present invention is applied to a heat pump, and FIG. 3 is an operation of the embodiment of the present invention. FIG. 4 is a block diagram for explaining the above, FIG. 4 is a flow chart showing the operation of one embodiment of the present invention, and FIG. 5 is a diagram showing the configuration of a conventional example. 5 ... Liquid reservoir, 10, 11 ... Temperature sensor, 12 ... Control section.

Claims (1)

[Claims] 1. A refrigeration cycle comprising a compressor, a condenser, an electronic expansion valve, and an evaporator, the condensation pressure saturation temperature of the refrigerant and the temperature of the condensed refrigerant before being expanded by the electronic expansion valve are detected to detect the refrigerant. The degree of supercooling of the refrigerant is provided, and a control means for controlling the opening degree of the electronic expansion valve based on the refrigerant supercooling degree is provided, and the refrigerant connecting the electronic expansion valve and the evaporator around the suction pipe of the compressor. A refrigeration cycle comprising a pipe and a refrigerant liquid reservoir connected to the pipe via the pipe.