JPH0377424B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention comprises a refrigeration cycle formed of a compressor, an indoor heat exchanger, an outdoor heat exchanger, an expansion valve, and a four-way valve as main components. The present invention relates to a heat pump type air conditioner, and in particular to control of the opening degree of an expansion valve.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 58-208568, a conventional heat pump air conditioner has temperature sensors installed between the suction pipe of the compressor and the evaporator, and each temperature sensor measures the temperature of the intake gas. There is a method of controlling the flow rate by detecting the evaporation temperature and adjusting the opening degree of a refrigerant flow control valve so that the difference between the two temperatures is constant.

[Problem that the invention seeks to solve]

In the heat pump air conditioner, the outdoor heat exchanger acts as an evaporator during heating operation, and the indoor heat exchanger acts as an evaporator during cooling operation, so two temperature sensors are required to detect the evaporation temperature. In other words, it is necessary to provide three temperature sensors to control the flow rate of the refrigerant. Additionally, as the heat load changes indoors and outdoors, the refrigerant in the middle of the evaporator, that is, the part where the temperature sensor is attached, may overheat, making it impossible to always detect a stable evaporation temperature.
Accurate flow control becomes impossible.

An object of the present invention is to provide a heat pump type air conditioner that can always perform accurate flow control using two temperature sensors.

[Means for solving problems]

The above purpose is to provide a branch pipe that branches upward from the middle of the refrigerant pipe leading from the discharge port of the compressor to the four-way valve and whose free end is sealed, and to install a branch pipe near the free end of the branch pipe. A first temperature sensor is provided to detect the condensation temperature of the refrigerant condensed in the branch pipe, and a second temperature sensor is provided to detect the discharge gas temperature of the compressor, which is detected by the first and second temperature sensors. This is achieved by providing a controller that calculates the temperature difference between the condensation temperature and the discharge gas temperature and provides a signal based on the result to the expansion valve to control the opening degree.

[Effect]

The refrigerant flowing into the branch pipe is cooled by outside air at its free end and condensed, and the condensation temperature reaches the first
Detected by temperature sensor. Further, the discharge gas temperature of the compressor is detected by a second temperature sensor,
Detection signals from each temperature sensor are input to the controller. The controller calculates the temperature difference between the condensation temperature and the discharge gas temperature, and outputs a signal based on the result to the expansion valve to control the opening degree. The condensed refrigerant in the branch pipe flows down and returns into the refrigeration cycle.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a refrigeration cycle diagram of a heat pump type air conditioner according to the present invention, and FIG. 2 shows an enlarged view of section A in FIG. In the figure, 1 is a compressor, 2 is an indoor heat exchanger, 3 is an outdoor heat exchanger, 4 is an expansion valve, 5
is a four-way valve, and these devices are connected via piping as shown to form a refrigeration cycle. From the discharge port of the compressor 1 in this refrigeration cycle to the four-way valve 5
The pipe 6 leading to the pipe has a branch pipe 7 branching from the pipe.
is provided. This branch pipe 7 is provided so as to stand up in a hook shape, and its free end 7a is sealed. The branch pipe 7 may be left as a bare pipe or may be provided with cooling fins so as to be in contact with the outside air. Further, a first temperature sensor 8 is installed near the free end 7a of the branch pipe 7 to detect the condensation temperature of the refrigerant condensed within the branch pipe 7.

On the other hand, a second temperature sensor 9 is installed in the discharge pipe of the compressor 1 to detect the temperature of the discharged gas. Further, the first and second temperature sensors 8, 9
A controller 10 is provided that calculates the temperature difference between the condensation temperature detected by and the discharge gas temperature, and outputs a signal based on the result to the expansion valve 4 to control the opening degree.

Next, the operation of this embodiment will be explained.

During heating operation, high-temperature, high-pressure refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 2 through the four-way valve 5, where it is cooled by air or the like and condensed and liquefied. After the liquid refrigerant is depressurized by the expansion valve 4, it flows into the outdoor heat exchanger 3, where it absorbs heat from the outside and evaporates. Thereafter, the gas refrigerant is drawn into the compressor 1 through the four-way valve 5.

During the above-mentioned heating, there is a pipe 6 inside the branch pipe 7.
A part of the gas refrigerant flowing through the pipe flows in, is cooled by the outside air, and condenses into a liquid. This liquid refrigerant flows down along the inner wall of the branch pipe 7, returns to the pipe 6, and circulates within the cycle. Then, at the same time that the liquid refrigerant flows out of the branch pipe 7, the gas refrigerant flows into the branch pipe 7 from the pipe 6. On the other hand, the condensation temperature of the liquid refrigerant in the branch pipe 7 is detected by the first temperature sensor 8, the discharge gas temperature of the compressor 1 is detected by the second temperature sensor 9, and each detection signal is input to the controller 10. . The controller 10 calculates the temperature difference between the condensation temperature and the discharge gas temperature, and outputs a signal based on the result to the expansion valve 4 to control the opening degree. This controls the flow rate of the refrigerant.

During cooling operation, the four-way valve 5 is switched so that the refrigerant discharged from the compressor 1 is switched between the four-way valve 5,
The outdoor heat exchanger 3, the expansion valve 4, the indoor heat exchanger 2, the four-way valve 5, and the compressor 1 are circulated in this order, that is, the indoor heat exchanger 2 becomes an evaporator, contrary to the heating operation.
The outdoor heat exchanger 3 becomes a condenser. At this time, the condensation temperature in the branch pipe 7 is detected by the first temperature sensor 8, and the discharge gas temperature is detected by the second temperature sensor 9, and the opening degree of the expansion valve 4 is controlled to control the flow rate of the refrigerant. be done.

Therefore, in this embodiment, the flow rate of the refrigerant is determined by two temperature sensors: a first temperature sensor 8 that detects the condensation temperature of the branch pipe 7, and a second temperature sensor 9 that detects the discharge gas temperature. can be controlled. In addition, in the branch pipe 7 of the condensation temperature detection section, the process of the condensed liquid refrigerant flowing down and returning to the cycle and the gas refrigerant flowing in at the same time is repeated, so the first temperature sensor 8 ensures stable condensation. Temperature is detected. As a result, accurate control of the refrigerant flow rate can be performed at all times.

In the present invention, as shown in FIG. 3, the piping 6 may be provided with a branch pipe 17 that rises at an angle.

〔Effect of the invention〕

As explained above, according to the present invention, accurate flow control can always be performed using two temperature sensors.

[Brief explanation of drawings]

FIG. 1 is a refrigeration cycle diagram showing one embodiment of the heat pump type air conditioner of the present invention, FIG. 2 is an enlarged view of section A in FIG. 1, and FIG. 3 is a diagram showing a modification of the branch pipe. 1... Compressor, 2... Indoor heat exchanger, 3... Outdoor heat exchanger, 4... Expansion valve, 5... Four-way valve, 7, 17...
Branch pipe, 8...first temperature sensor, 9...second temperature sensor, 10...controller.

Claims (1)

[Claims] 1 Compressor, indoor heat exchanger, outdoor heat exchanger,
In a heat pump air conditioner equipped with a refrigeration cycle formed mainly of an expansion valve and a four-way valve, a refrigerant pipe that branches upward from the middle of the refrigerant pipe from the discharge port of the compressor to the four-way valve, and has a free end. A first temperature sensor is provided near the free end of the branch pipe to detect the condensation temperature of the refrigerant condensed in the branch pipe, and a first temperature sensor is provided near the free end of the branch pipe to detect the temperature of the gas discharged from the compressor. A second temperature sensor is provided to calculate the temperature difference between the condensation temperature detected by the first and second temperature sensors and the discharge gas temperature, and a signal based on the result is provided to the expansion valve to control the opening degree. A heat pump type air conditioner characterized by being equipped with a controller.