JPH04273954A - Refrigerant amount adjusting device in refrigerating cycle - Google Patents

Abstract

PURPOSE:To maintain the amount of refrigerant circulated at an appropriate level by a method wherein, in an air conditioning machine having the devices as shown in the diagram, a pair of pressure reducing devices for recycling side is provided in series connection between indoor and outdoor heat exchangers, a bypass passage connects the discharge and suction sides of a compressor and has a pair of pressure reducing devices for the bypass side connected in series and a liquid tank is disposed in communication with an intermediate point between each pair of the pressure reducing devices. CONSTITUTION:A refrigerating cycle which comprises a compressor 1; a four- way valve 2, an outdoor heat exchanger 3; a pair of pressure reducing devices 4a and 4b for refrigerating cycle side provided in series connection; an indoor heat exchanger 5, the pressure reducing devices 4a and 4b being located between the outdoor and indoor heat exchangers 3 and 5; a bypass passage 6 connecting the discharge and the suction sides of a compressor 2 and having a pair of pressure reducing devices 7a and 7b for the bypass side connected in series; and a liquid tank 9 disposed in communication with an intermediate point between each pair of the pressure reducing devices 4a, 4b and 7a, 7b.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle for an air conditioner, and more particularly to a refrigerant amount adjusting device for a refrigeration cycle that can maintain an appropriate amount of refrigerant circulating within the refrigeration cycle.

0002

2. Description of the Related Art As shown in FIG. 3, the refrigeration cycle of an air conditioner consists of a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a pressure reducing device 4 such as an expansion valve, and an indoor heat exchanger 5 connected in sequence. Therefore, during cooling, high-temperature, high-pressure refrigerant gas from the compressor 1 is passed through the outdoor heat exchanger 3 to be condensed, reduced in pressure by the pressure reducing device 4, and evaporated in the indoor heat exchanger 5 to perform indoor cooling. The refrigerant gas is returned to the compressor 1, and during heating, the four-way valve 2 is switched to flow the high-temperature, high-pressure refrigerant gas to the indoor heat exchanger 5, in the opposite direction to that during cooling, where it is condensed to heat the room, and after being depressurized by the pressure reducing device 4, It is evaporated in the outdoor heat exchanger 3 and returned to the compressor.

[0003] In this refrigeration cycle, the opening degree of the pressure reducing device is controlled by the suction temperature of the compressor 1, and when the suction temperature is high, the opening degree is opened, and when the suction temperature is low, the opening degree is narrowed. is controlled.

0004

[Problem to be solved by the invention] However, when the amount of refrigerant sealed in this refrigeration cycle is excessive,
Liquid refrigerant tends to accumulate in the heat exchanger on the condensing side, and the heat dissipation performance of the heat exchanger decreases, causing problems such as an increase in power consumption of the compressor 1 and a decrease in refrigeration capacity (cooling and heating capacity). Furthermore, in the worst case, the refrigerant is not sufficiently evaporated in the evaporation side heat exchanger, causing liquid backflow in the compressor, which may cause a failure of the compressor.

[0005] Furthermore, in the case of a separate type refrigeration cycle such as a split type, the amount of refrigerant charged tends to change depending on the installation situation of the length of the connecting piping that connects the indoor unit and the outdoor unit, so it is necessary to keep the appropriate amount of refrigerant filled. This is difficult and requires adjustments such as addition and release of refrigerant, which poses a problem that leads to deterioration of the installation work.

Furthermore, even if the amount of refrigerant charged is appropriate, there may be a shortage or excess of refrigerant circulating in the cycle depending on the conditions of the heating and cooling operation, and it is not always possible to operate the refrigerant according to the load by simply controlling the opening of the pressure reducing device. There is a problem that cannot be done.

SUMMARY OF THE INVENTION An object of the present invention is to provide a refrigerant amount adjusting device for a refrigeration cycle that can solve the above-mentioned problems and maintain an appropriate amount of refrigerant circulating within the refrigeration cycle.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a refrigeration cycle in which a compressor, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are sequentially connected. Two cycle-side pressure reducing devices are connected in series between the exchanger, and a bypass passage connects the discharge side and suction side of the other compressor, and two bypass-side pressure reducing devices are connected in series to the bypass passage, The middle point between the pressure reducing devices on the cycle side and the bypass side is connected through a liquid tank.

[0009]

[Operation] According to the above configuration, by adjusting the opening degrees of the two pressure reducing devices on the cycle side according to the operating conditions, the pressure difference between the pressure reducing devices on the cycle side and the pressure reducing device on the bypass side can be adjusted. Thereby, the refrigerant liquid accumulated in the liquid tank can be returned to the refrigeration cycle, or the refrigerant in the refrigeration cycle can be stored in the liquid tank, so that the amount of refrigerant circulated that substantially flows through the refrigeration cycle can be optimally adjusted.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

In FIG. 1, 1 is a compressor, 2 is a four-way valve,
3 is an outdoor heat exchanger, 4a and 4b are cycle-side first and second pressure reducing devices consisting of two electronic expansion valves connected in series, and 4 is an indoor heat exchanger, which are connected in sequence to form a refrigeration cycle. configured.

The discharge side and suction side of the compressor 1 are connected by a bypass passage 6, and two bypass side first and second pressure reducing devices 7a and 7b, each made of a capillary tube or the like, are connected in series to the bypass passage 6. be done.

[0013] This cycle side first and second pressure reducing devices 4a
, 4b and the bypass side first and second pressure reducing devices 7
The intermediate point B between a and 7b is connected by a communication pipe 8, and a liquid tank 9 is connected to the pipe 8. This liquid tank 9 is provided to stand up substantially vertically, and its bottom portion is connected to the intermediate point A side, and its upper portion is connected to the intermediate point B side.

[0014] This refrigeration cycle is provided with a sensor for detecting the refrigerant temperature at each location. That is, the suction side piping of the compressor 1 is provided with a suction temperature sensor 10, and the outdoor heat exchanger 3 is provided with an outdoor heat exchange intermediate temperature sensor 11, and the outlet side of the heat exchanger 3 during cooling is provided with an outdoor heat exchanger intermediate temperature sensor 11. is provided with an outlet temperature sensor 12. Further, the indoor heat exchanger 5 is provided with an indoor heat exchange intermediate temperature sensor 13, and an outlet temperature sensor 14 is provided on the exit side during heating.

A liquid level detection sensor 1 is installed in the liquid tank 9.
5 is provided.

These sensors 10, 11, 12, 13, 1
The detected values 4 and 15 are input to the control device 16, and the cycle side first and second pressure reducing devices 4a and 4b are activated according to the detected values.
The valve opening degree of the valve is controlled.

Next, the operation of this embodiment will be explained.

During cooling operation, high-temperature, high-pressure refrigerant gas from the compressor 1 flows through the four-way valve 2 to the outdoor heat exchanger 3, where it is condensed, and is then transferred to the cycle-side first and second pressure reducing devices 4a, 4b.
After being evaporated in the indoor heat exchanger 5 to cool the room, it is returned to the compressor 1 via the four-way valve 2. In addition, during heating operation, high-temperature, high-pressure refrigerant gas flows into the indoor heat exchanger 5 by switching the four-way valve 2, contrary to the case during cooling, and is condensed there to heat the room.
After being depressurized in b and 4a, it flows to the outdoor heat exchanger 3, where it is evaporated and returned to the compressor 1.

During this heating and cooling operation, a part of the high temperature and high pressure refrigerant gas from the compressor 1 flows into the bypass passage 6 and returns to the compressor 1 through the bypass side first and second pressure reducing devices 7a and 7b. Intermediate point B between the first and second pressure reducing devices 7a and 7b on the side and the first and second pressure reducing devices 4a and 4b on the cycle side
Due to the pressure difference between intermediate points A, that is, when the pressure at intermediate point A is higher than intermediate point B, the liquid is supplied into the tank 9 from the first pressure reducing device 4a on the cycle side during cooling, and from the second pressure reducing device on the cycle side during heating. The refrigerant liquid from 4b flows in and is stored, and when the pressure at intermediate point A is lower than the pressure at intermediate point B, the refrigerant liquid in liquid tank 9 is transferred to the evaporator (indoor heat exchanger 5 during cooling, indoor heat exchanger 5 during heating) flows to the outdoor heat exchanger 3), and the amount of refrigerant circulated within the refrigeration cycle is adjusted.

The control device 16 controls the amount of refrigerant circulated within the refrigeration cycle using the sensors 10, 11, 12, 13,
From the detected value of 14, the cycle side first and second pressure reducing devices 4a
, 4b by adjusting the opening degree. That is, the control device 16 detects the magnitude of undercooling and superheating in the refrigeration cycle from the detected values of the sensors 10, 11, 12, 13, and 14, and adjusts the first and second reduced pressures on the cycle side accordingly. Adjust the opening degrees of devices 4a and 4b. First, undercool is the outdoor heat exchanger intermediate temperature sensor 1 during cooling.
1 and the outlet temperature sensor 12, and also from the temperature difference between the indoor heat exchange intermediate temperature sensor 13 and the outlet temperature sensor 14 during heating. In addition, superheat is caused by the temperature difference between the cooling suction temperature sensor 10 and the outlet temperature sensor 14 (or the outdoor heat exchanger intermediate temperature sensor 11), the heating suction temperature sensor 10 and the outlet temperature sensor 14 (or the indoor heat exchanger intermediate temperature sensor 13), )
Calculated from the temperature difference between

When this undercool is large, the refrigerant circulation amount is large and the liquid is stored in the liquid tank 9, and when it is small, the refrigerant liquid in the liquid tank 9 is returned to the refrigeration cycle by the cycle side first and second The opening degrees of the pressure reducing devices 4a and 4b are adjusted, and when the superheat is large, the opening degrees of the first and second pressure reducing devices 4a and 4b are adjusted, and when the superheat is small, the opening degrees of the first and second pressure reducing devices 4a on the cycle side are adjusted. , 4b to narrow the opening. Further, the refrigerant liquid in the liquid tank 9 is detected by a liquid level detection sensor 15, and when the refrigerant liquid in the tank 9 is full or empty, the control device 16 stops the operation of the compressor 1.

Next, this control device 16 will be explained in more detail based on the flowchart of FIG.

First, this flowchart shows an example during cooling operation. When cooling operation is started, it is determined 20 whether the undercool is larger or smaller than the set range, and if it is larger, the first pressure reducing device 4a is activated. The opening degree adjustment 21 is performed in the opening direction and in the closing direction of the second pressure reducing device 4b. Due to this opening adjustment, the pressure at intermediate point A becomes higher than the pressure at intermediate point B.
Since the condensed refrigerant from the first pressure reducing device 4a is stored in the liquid tank 9, undercooling is adjusted to be appropriate. Further, if the undercool is smaller than the setting in judgment 20, the first pressure reducing device 4a is moved to the closing direction, and the second pressure reducing device 4b is moved to the closing direction.
Opening adjustment 22 is performed in the opening direction. By adjusting the opening, the pressure at intermediate point A becomes lower than the pressure at intermediate point B, and the liquid refrigerant in the tank 9 is supplied to the cycle side via the second pressure reducing device 4b, so that the undercooling is adjusted to be appropriate. be done.

Next, if the undercool is appropriate, it is then determined 23 whether the superheat is larger or smaller than the set range, and if it is, the first and second pressure reducing devices 4a and 4b are activated to prevent overheating. Adjustment 2 to lower the super heat to the appropriate value by opening both in the opening direction and lowering the degree of decompression.
4, and if the superheat is small, adjustment 25 is performed to increase the superheat to an appropriate value by narrowing the opening degrees of both the first and second pressure reducing devices 4a and 4b in the closing direction in order to prevent liquid back. Furthermore, if the superheat is appropriate, the liquid level is next determined 26, and if the tank is full or empty, an abnormal stop process 27 such as stopping the compressor is performed.

[0025]

In summary, according to the present invention, two pressure reducing devices are provided in the refrigeration cycle, and two bypass side pressure reducing devices are connected between the discharge side and the suction side of the compressor. By communicating the intermediate point of the pressure reducing device with a liquid tank, the opening degree of the pressure reducing device on the bypass side can be adjusted to return the refrigerant liquid accumulated in the liquid tank to the refrigeration cycle, or to transfer the refrigerant in the refrigeration cycle to the liquid tank. By storing the refrigerant, it is possible to optimally adjust the circulating amount of refrigerant that essentially flows through the refrigeration cycle. Therefore, problems such as (1) excessive undercooling and deterioration of performance on the condensing side, increased power consumption, and decreased refrigerating capacity are eliminated. (2) When there is an excess of refrigerant, liquid refrigerant returns to the compressor, eliminating the risk of malfunction. (3) There is no need to make adjustments such as adding or releasing refrigerant during construction, improving workability. (4) When connecting indoor units of different types, the amount of refrigerant, throttle, etc. are self-adjusted, reducing the development load. (5) It is possible to always perform optimal control even under different air conditioning conditions.

[Brief explanation of the drawing]

FIG. 1 is a refrigeration cycle diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing a flowchart of the present invention.

FIG. 3 is a diagram showing a conventional refrigeration cycle.

[Explanation of symbols]

1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4a, 4b Cycle side pressure reducing device 5 Indoor heat exchanger 7a, 7b Bypass side pressure reducing device 9 Liquid tank

Claims (1)

[Claims] Claim 1: In a refrigeration cycle in which a compressor, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are connected in sequence, two cycle-side pressure reducing devices are connected in series between the outdoor heat exchanger and the indoor heat exchanger. On the other hand, the discharge side and suction side of the compressor are connected by a bypass passage, and two bypass side pressure reducing devices are connected in series to the bypass passage, and the intermediate point between the cycle side and bypass side pressure reducing devices is connected to the liquid tank. A refrigerant amount adjusting device for a refrigeration cycle, characterized in that the device communicates with the refrigerant amount.