JPH0689963B2 - Heat pump type air conditioner - Google Patents

Description

The present invention relates to a heat pump type heating / cooling device having one outdoor unit and a plurality of indoor units, for example, an office cooling / heating system for a building or the like. Used for air conditioning.

(Prior Art) As a prior art relating to the present invention, there is one described in Japanese Patent Publication No. 52-16577.

This prior art will be described with reference to FIG. 3. During cooling, the high-temperature and high-pressure refrigerant gas discharged from the compressor 32 enters the outdoor heat exchanger 34, radiates heat to the outside air, and the condensed and liquefied refrigerant passes through the liquid branch point 42. After that, the indoor unit 36a configured in parallel,
The pressure is reduced by the capillary tubes 39a, 39b in 36b, the heat is absorbed from the indoor air of the indoor heat exchangers 37a, 37b and evaporated, and then flows in the order of the branch point 43 and the four-way valve 33 and is sucked into the compressor 32.

On the other hand, during the heating operation, the high-temperature and high-pressure refrigerant gas discharged from the compressor 32 passes through the four-way valve 33, the pipe 41, the branch point 43, and the indoor heat exchangers 37a, 37b with a fan 38a with a motor for blowing it. The room air sent by 38b is overheated and condensed and liquefied. Then, the pressure is reduced by the capillary tubes 39a, 39b, flows in the order of the branch pipes 40a, 40b, the branch point 42, absorbs heat in the outdoor heat exchanger 34, evaporates, and is sucked into the compressor 32.

(Problems to be solved by the invention) However, in this conventional technique, when the air volumes of the indoor unit and the fan with the motor are different from each other during the heating operation, or when there is a difference in the air temperature sucked by the fan, A large difference occurs in the degree of condensation and the temperature of the refrigerant flowing into the capillary tube. Explaining this with the pressure enthalpy diagram of FIG. 4, Pe is the condensation pressure and Pc is the evaporation pressure. A is the state before the compressor, B is the state at the inlet of the condenser, C is the state before the capillary tube, and D is the state before the evaporator. If there is a difference in room temperature or if the fan air volume is different,
Point C changes to points Ca and Cb, respectively. Looking at Cb,
Here, the refrigerant is not completely condensed, does not have an appropriate degree of supercooling, does not effectively absorb heat from the outside air in the evaporator, and lowers the coefficient of performance of the device. Regarding Ca, the degree of supercooling is excessive, and the refrigerant flow rate is relatively insufficient with respect to the indoor heating demand.

In view of such a problem, the present invention makes it a technical subject to improve the coefficient of performance during heating.

[Structure of Invention]

(Means for Solving Problems) Technical means taken to solve the above-mentioned problems are as follows: a compressor, a pressure sensor for detecting a discharge pressure, and a pressure detected by the pressure sensor in an outdoor unit. A controller for controlling the number of revolutions of the compressor to keep it constant and a prime mover are provided, and an expansion valve for cooling operation arranged in the liquid pipe in the indoor unit, and arranged in parallel with the expansion valve. A check valve and a temperature-sensitive flow control valve.

(Operation) According to this, during the heating operation, the pressure in the indoor heat exchanger, that is, the condensing pressure is kept at the set value regardless of the rotation speed of the fan motor and the indoor temperature, and further, by the function of the temperature-sensitive flow rate control, By maintaining the temperature of the refrigerant liquid passing therethrough at a preset temperature, the coefficient of performance of the heat pump cycle can always be maintained at a high value.

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

Reference numeral 1 denotes an outdoor unit, a compressor 2, a pressure sensor 3 for detecting high-temperature and high-pressure refrigerant gas discharged from the compressor 2, a prime mover 5 for changing the rotational speed of the compressor 2 by a controller 4, a four-way valve 6 The outdoor heat exchanger 7, a fan with motor 8 for blowing air to the outdoor heat exchanger 7, an expansion valve 9, and a check valve 10.

11a and 11b are indoor units, and indoor heat exchangers 12a and 12b
A fan with motor 13a, 13b for blowing air to the indoor heat exchangers 12a, 12b, expansion valves 14a, 14b, temperature-sensitive flow control valves 20a, 20b in parallel with the expansion valves 14a, 14b, and a check valve 15a. , 15b.

The outdoor unit 1 and the indoor units 11a and 11b are pipes 16 and 17
And branch pipes 16a, 16b, 17a, 17b branched at the midway branch points 18 and 19
Better connected.

The temperature-sensitive flow control valves 20a and 20b form a refrigerant liquid inlet 21 as shown in FIG. 2, and a casing 22 has a temperature-sensitive tube 24 filled with a wax 23 that causes a volume change depending on a set temperature. When,
Valve rod 2 that changes the head according to the volume change of wax 23
5, and a spring 26 that prevents the valve rod 25 from rattling.

When the cooling operation is performed with the above configuration, the high-temperature and high-pressure gas discharged from the compressor 2 radiates heat from the four-way valve 6 to the outdoor heat exchanger 7 to be condensed and liquefied. The condensed and liquefied refrigerant passes through the check valve 10, and at the branch point 18, each indoor unit 11a, 11
expansion valve 14a, 14b via branch pipes 16a, 16b
The indoor heat exchangers 12a, 12b absorb heat from the indoor air and become a gas state to cool the room, and the branch pipe 17
It is sucked into the compressor 2 through the branch point 19 and the four-way valve 6 by a and 17b.

Here, although the suction pressure of the compressor 2 changes depending on the fan air volume of each indoor unit 11a, 11b and the cooling load, the change of the suction pressure is detected by the pressure sensor 3 ', and the controller 4 detects the rotation speed of the prime mover 5, that is, The rotation speed of the compressor 2 is controlled to keep the suction pressure at the set value. As a result, the indoor heat exchanger 12
Since the evaporation temperatures in a and 12b can be kept at the set values, the cold air blowing temperature can be kept almost constant. At this time, the refrigerant does not flow into the temperature-sensitive flow control valves 20a and 20b due to the action of the check valves 15a and 15b installed in series therewith.

On the other hand, when the heating operation is performed, the high-temperature and high-pressure refrigerant gas discharged from the compressor 2 enters the branch point 19 from the four-way valve 6 and the branch pipe 17
After passing through a and 17b, the indoor heat exchangers 12a and 12b radiate heat to indoor air and condense into a cooling liquid. After this, the temperature sensitive flow control valve 20
a, 20b, non-return valves 15a, 15b and branch pipes 16a, 16b to join at a branch point 18, the expansion valve 9 reduces the pressure, and the outdoor heat exchanger 7 absorbs heat and evaporates from the outside air. , Through the four-way valve 6,
It is sucked into the compressor 2.

The temperature-sensitive flow control valves 20a, 20b, the refrigerant higher than the set liquid temperature throttles the passage, liquefies in the indoor heat exchanger 12a, 12b, and then the heat exchanger 12a so that the liquid temperature falls to the set temperature. , 12b
The liquid level in the heat exchangers 12a, 12b is lowered by increasing the liquid level in the heat exchanger 12a, 12b when a refrigerant lower than the set value passes, and the liquid flowing through each of them is reduced as a result. It keeps the temperature constant.

Here, the pressure (condensation pressure) of the indoor heat exchangers 12a and 12b is kept at a set value by controlling the rotation speed of the prime mover 5, that is, the rotation speed of the compressor 2 by the discharge pressure sensor 3 and the controller 4. Therefore, as a result, the so-called supercooling degree of the refrigerant passing through the temperature-sensitive flow control valves 20a and 20b can be kept constant.

[Advantages of the Invention] As described above, during heating, the condensing pressure is kept constant by controlling the compressor rotation speed, and the temperature of the refrigerant condensate is kept constant by the temperature-sensitive flow control valve. A high coefficient of performance can be maintained at all times regardless of room temperature and fan air volume, and the temperature of air blown out from the indoor unit can be kept almost constant.

Also, when one indoor unit stops operating, the gaseous refrigerant circulates in this unit as well, but the heat dissipation in this unit is small, and it remains in the gaseous state and accumulates in the resting indoor unit. Therefore, the refrigerant does not accumulate, so that the heating operation can be performed without causing the circulating refrigerant amount to become insufficient or excessive.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of the device of the present invention, and FIG.
FIG. 3 is a sectional view of the temperature-sensitive flow control valve, FIG. 3 is a refrigerant circuit diagram of a conventional device, and FIG. 4 is a pressure enthalpy diagram. 1 …… Outdoor unit, 2 …… Compressor, 3 …… Pressure sensor, 4
...... Controller, 5 …… Motor, 11a, 11b …… Indoor unit, 13a, 13b …… Expansion valve, 14a, 14b …… Check valve, 20a, 20b ……
Temperature-sensitive flow control valve

Claims (1)

[Claims] 1. A heat pump type cooling and heating apparatus having one outdoor unit and a plurality of indoor units, wherein the outdoor unit is a compressor, a pressure sensor for detecting a discharge pressure, and a pressure detected by the pressure sensor. A controller for controlling the number of revolutions of the compressor in order to keep constant
The indoor unit has an expansion valve for cooling operation arranged in the liquid pipe, and a check valve and a temperature-sensitive flow control valve arranged in parallel with the expansion valve. Heat pump type air conditioner.