JPS63290368A - Heat pump type air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention employs an electric expansion valve as a refrigerant flow rate control device, and controls the connection to an indoor heat exchanger when the air temperature inside and outside the room is low. Related to a heat pump air conditioner with a frost prevention function.

BACKGROUND OF THE INVENTION In recent years, heat pump air conditioners have adopted an electric expansion valve as a refrigerant control device for a refrigeration cycle in order to determine the optimum flow rate of refrigerant for the operating conditions.

An example of a conventional refrigerant control device for a heat pump air conditioner will be described below with reference to the drawings. Fig. 4 shows a cooling system diagram of a conventional heat pump air conditioner using an electric expansion valve as a refrigerant control device, in which 1 is a compressor, 2 is an outdoor heat exchanger that acts as a condenser during cooling, 3 is an electric expansion valve that functions as a pressure reducing device during heating operation;
4 is an electric expansion valve that functions as a pressure reducing device during cooling operation; 5
is an indoor heat exchanger that acts as an evaporator during cooling, and these are connected in a ring to form a refrigeration cycle. 8 indicates the temperature detected by the pipe temperature sensor 22 at the intermediate part of the outdoor heat exchanger 2 and the pipe temperature sensor 2 at the outlet part during heating operation.
1 is a controller that calculates the difference in detected temperatures and outputs an operation for changing the opening degree of the electric expansion valve 3. Similarly, 3o represents the temperature detected by the piping temperature sensor 24 at the intermediate portion of the indoor heat exchanger 6 and the piping temperature sensor 23 at the outlet portion during cooling operation.
This is a controller that calculates the difference in temperature detected by the controller and outputs an operation for changing the opening degree of the electric expansion valve 4. Reference numeral 10 denotes a refrigerant pipe for a liquid bypass circuit, and during cooling, a solenoid valve 11 is connected between a refrigerant pipe 16 led out from the outdoor heat exchanger 2 serving as a condenser and a refrigerant pipe 170 led out from the indoor heat exchanger 6 serving as an evaporator. They are connected via a capillary tube 12. 13 is a refrigerant pipe for the discharge gas bypass circuit, and the refrigerant pipe 1 leads out from the compressor.
8 and a refrigerant pipe 19 introduced into the accumulator 20 are connected via a solenoid valve 14 and a capillary 16. Reference numeral 6 indicates a high-pressure filter which stops the operation of the compressor 1 when the discharge pressure exceeds a certain value. 7 is a four-way valve that switches between cooling and heating cycles.

The operation of the air conditioner configured as above will be described below.

During cooling operation, high-temperature, high-pressure refrigerant gas compressed by the compressor 1 passes through the refrigerant pipe 18 and the four-way valve 7, and is liquefied in the outdoor heat exchanger 2. During cooling, the electric expansion valve 3 is fully opened and the pressure is not reduced at this time, so high-pressure liquid refrigerant enters the indoor unit. Furthermore, it is adiabatically expanded in the electric expansion valve 4 of the indoor unit to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, which is evaporated and gasified in the indoor heat exchanger 5, reaches the accumulator 20, and is transferred to the compressor 1. Return to repeat the cycle.

Next, a method of controlling the refrigerant flow rate using the electric expansion valve 4 will be explained. The temperature difference measuring means 30a determines the temperature difference from the temperature sensors 24.23 provided at the intermediate part and the outlet part of the indoor heat exchanger 6, and based on the temperature difference, the electric expansion valve opening determining means 30b opens the valve. Based on the determination, the electric expansion valve control means 30c controls the electric expansion valve 4 to adjust and set the valve opening degree.

Control.

Next, heating will be explained. During heating operation, high-temperature, high-pressure refrigerant gas compressed by the compressor 1 passes through the refrigerant pipe 18 and the four-way valve 7, and is liquefied in the indoor heat exchanger 5. During heating, the electric expansion valve 4 is fully opened, and the refrigerant is supplied to the outdoor unit through the refrigerant pipe 16.
High pressure liquid refrigerant enters.

Furthermore, it is adiabatically expanded in the electric expansion valve 3 on the outdoor unit side to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, which is then evaporated and evaporated in the outdoor heat exchanger 2.
The cycle of gasification, reaching the accumulator 20, and returning to the compressor 1 is repeated.

Next, a method of controlling the refrigerant flow rate using the electric expansion valve 3 will be explained. By detecting the pipe temperatures between the intermediate section and the outlet section of the outdoor heat exchanger 2 using the temperature sensors 21 and 22, the electric expansion valve 3 is controlled according to the difference in temperature in the same manner as the controller 30 of the indoor unit. Control. Next, referring to FIG. 6, a description will be given of a low outside temperature for cooling when the air temperature on the indoor side and the outdoor side decreases. When the air temperature on the indoor side and the outdoor side decreases, and the outside air temperature is low, frost forms on the indoor heat exchanger 5.
As frosting progresses, the pressure at the outlet of the indoor heat exchanger 6 decreases, and the pipe temperature at the outlet of the indoor heat exchanger 6 gradually decreases. (0
<t<T1) When this temperature reaches the set value, the solenoid valve 14
opens and a part of the discharge gas flowing from the compressor 1 into the refrigerant pipe 18 is introduced into the refrigerant pipe 13 for the discharge gas bypass circuit, passes through the capillary tube 16, and is bypassed to the refrigerant pipe 19 at the inlet of the accumulator 2o. 11 is also opened, and a part of the liquid refrigerant flowing out from the outdoor heat exchanger 2 is introduced into the liquid bypass circuit refrigerant pipe 10, passes through the capillary tube 12, and is similarly bypassed to the refrigerant pipe 19 at the inlet of the accumulator 2o. , keeping the degree of superheat of the suction gas constant. (T1<t<T2) When the pipe temperature at the outlet of the indoor heat exchanger 5 returns to the normal state, the solenoid valves 11 and 14 are closed, and the operation returns to the original standard time. (T3<t) Problem to be Solved by the Invention However, in the above configuration, when the outside temperature is low for cooling, hot gas and a small amount of liquid refrigerant are directly supplied to the accumulator 2 through the solenoid valve 14 and the capillary tube 16.
In order to return the refrigerant to the refrigerant pipe at the inlet of the refrigerant, the capacity of the returned hot gas and liquid cooling medium is reduced, and a solenoid valve 14 and a capillary tube 16 must be installed for the hot gas and liquid bypass circuit 13. Another problem was that the cost was high.

In view of the above-mentioned problems, the present invention provides a heat pump type air conditioner having a function of preventing frost formation on an indoor heat exchanger by effectively using only an electric expansion valve when the outside temperature is low. be.

Means for Solving the Problems In order to solve the above problems, the heat pump type air conditioner of the present invention reduces the opening degree of the electric expansion valve when the outside air temperature is low and the indoor and outdoor air temperatures drop. It has a configuration in which it can be set to a large value.

Effect of the Invention With the above-described configuration, the present invention is capable of increasing the temperature of the indoor heat exchanger by setting the opening degree of the electric expansion valve to a large value when the outside temperature is low for cooling and the air temperature on the indoor side and the outdoor side decreases. , frost formation on the indoor heat exchanger can be prevented.

EXAMPLE Hereinafter, a heat pump air conditioner according to an example of the present invention will be described with reference to FIGS. 1, 2, and 3. In FIG. 1, the same parts as in FIG. 4 are indicated by the same symbols. Fig. 1 shows a cooling system diagram of a heat pump type air conditioner according to an embodiment of the present invention, Fig. 2 is a block diagram of a controller in an embodiment of the present invention, and Fig. 3 shows a cooling system diagram of a heat pump type air conditioner according to an embodiment of the present invention. This paper describes a method for controlling an electric expansion valve when the outside air temperature is low for cooling and the outside air temperature is low. 9 is a controller on the indoor side.

First, referring to FIG. 2, control of the electric expansion valve 4 on the indoor side during cooling will be explained. During cooling, the temperature difference is determined by the temperature difference measuring means 9a from the temperature sensors 24 and 23 provided at the intermediate part and the outlet part of the indoor heat exchanger 6, and the temperature difference is also measured by the temperature sensor 2.
The temperature obtained from step 3 is determined by the indoor heat exchanger outlet temperature measuring means 9b, and when the indoor heat exchanger outlet temperature is equal to or higher than o''c, the electric expansion valve opening degree determining means 9C determines the valve opening degree based on the temperature difference. The electric expansion valve control means 9 determines the opening degree and based on the opening degree.
d controls the electric expansion valve 4 and adjusts the valve opening degree.

Set and control. When the indoor heat exchanger outlet temperature is 0° C. or lower, the electric expansion valve opening determination means 9C determines the valve opening to be fully open, and the electric expansion valve control means 9d controls the electric expansion valve 4 to open the valve. Adjust, set, and control degrees. The electric expansion valve control method during heating is the same as the conventional one, so a description thereof will be omitted.

FIG. 3 particularly shows the behavior when the outside air temperature is low for cooling, in which the air temperature on the indoor side and the outdoor side decreases, in conjunction with the control of the electric expansion valve 4.

When the outside air temperature is low for cooling, the evaporation pressure decreases, and the indoor heat exchanger outlet temperature decreases accordingly.

(0<t<T1) and the indoor heat exchanger outlet temperature is O'
When the temperature drops to C, the electric expansion valve 4 is fully opened to increase the evaporation pressure and prevent the indoor heat exchanger 5 from forming frost. Therefore, in this embodiment, when the outside air temperature is low for cooling, the cycle is balanced with refrigerant accumulated in the accumulator 20 in order to fully open the electric expansion valve 4. (
T, <t<T2) When the indoor heat exchanger outlet temperature rises to 2°C, the electric expansion valve 4 is controlled based on the temperature difference.

(T2<t) As described above, according to this embodiment, by setting the opening degree of the electric expansion valve to a large value when the air temperature on the indoor side and the outdoor side is low and the outside air temperature is low, the indoor heat exchanger As the temperature of the indoor heat exchanger increases, frost formation on the indoor heat exchanger can be prevented.

Effects of the Invention As described above, the present invention has a control function that sets the electric expansion valve opening degree to a large value when the outside temperature is low for cooling, when the air temperature on the indoor side and the outdoor side decreases. Since frost can be prevented, solenoid valves and capillary tubes for hot gas and liquid bypass circuits are not required, and costs can be rationalized.

[Brief explanation of the drawing]

Figure 1 is a diagram of the cooling system of a heat pump air conditioner according to an embodiment of the present invention, Figure 2 is a block diagram of the controller in the air conditioner, and Figure 3 is the behavior of the cooling system at low outside temperatures. Fig. 4 is a diagram of the cooling system of a conventional heat pump air conditioner, Fig. 5 is a block diagram of the controller, and Fig. 6 is an explanatory diagram of the cooling behavior and control at low outside temperatures. It is. 1...Compressor, 4...Electric expansion valve, 6
...Indoor heat exchanger, 9...Controller. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
-13 guns encounter 4--Muro-ariaki Akichoju Fig. 2 4-Kyo 4 Kikariben ■--1- Fig. 3 Haku 4 Fig. 5 Burning Fig. 6

Claims (1)

[Claims] It is located in the refrigerant circuit of a heat pump air conditioner, which consists of a compressor, an indoor heat exchanger, an outdoor heat exchanger, etc. connected in a ring, and an electrically operated expansion device is installed between the indoor heat exchanger and the outdoor heat exchanger. 1. A heat pump type air conditioner, comprising a valve, and a control means for setting the electric expansion valve opening degree to a large value when the outside air temperature is low and the air temperature on the indoor side and the outdoor side decreases.