EP3091311B1

EP3091311B1 - Air-conditioning system and method for controlling air-conditioning system

Info

Publication number: EP3091311B1
Application number: EP14875380.9A
Authority: EP
Inventors: Shaobin Li; Yuhai Su; Qunbo LIU; Peigang SONG; Chun Huang; Hexin LIU; Zebin CHEN; Yingsheng FU; Yi Ni
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2013-12-24
Filing date: 2014-10-15
Publication date: 2019-02-27
Anticipated expiration: 2034-10-15
Also published as: EP3091311A1; TR201905512T4; ES2717515T3; JP2017502247A; JP6498677B2; EP3091311A4; CN104729130B; CN104729130A; WO2015096539A1

Description

Technical field of the invention

The disclosure relates to the field of air conditioners, and in particular to an air-conditioning system and a method for controlling an air-conditioning system.

Background of the invention

As shown in Fig. 1, a existing air-conditioning system includes a condenser 10, an evaporator 20, a capacity-variable and frequency-variable compressor 30, a throttling device 40, a four-way valve 60, a solenoid valve 70 and a one-way valve 50, wherein the capacity-variable and frequency-variable compressor 30 is switched by means of the motions of the one-way valve 50 and the solenoid valve 70. When the solenoid valve 70 is opened, a high-pressure coolant at an exhaust side flows to a suction port of a lower cylinder of the compressor, so that high pressure is formed at a suction end of the lower cylinder, and the capacity-variable and frequency-variable compressor 30 may operate with a single cylinder. When the solenoid valve 70 is closed, a low-pressure coolant of a gas-liquid separator flows to the suction port of the lower cylinder, so that low pressure is formed at the suction port of the lower cylinder, and the capacity-variable and frequency-variable compressor is switched to operate with double cylinders.
The prior art has the disadvantages as follows.

(1) When a single-cylinder operation is switched to a double-cylinder operation or a multi-cylinder operation, the solenoid valve is closed. However, since a connecting pipe from the suction port of the lower cylinder to the solenoid valve is still under a high-pressure state and the one-way valve is under a shut-off state due to the existence of a pressure difference, the low-pressure coolant of the gas-liquid separator cannot flow to a lower cylinder, thereby easily causing instability of the system during switching from the single-cylinder operation to the double-cylinder operation.
(2) During the single-cylinder operation, the connecting pipe from the lower cylinder of the compressor to the solenoid valve is at a high-pressure side. However, since the coolant is under a stationary state, the temperature of the coolant drops along with heat exchange for an environment temperature, and the coolant is easily condensed to a liquid state when the temperature drop lasts long. At this time, if the single-cylinder operation is switched to the double-cylinder operation, the liquid-state coolant will flow to the lower cylinder, so that a liquid impact is triggered for the lower cylinder, and therefore the compressor is damaged.
(3) In order to solve the problem in (1), if a capillary pipe is additionally provided at the connecting pipe of the suction port of the lower cylinder and the solenoid valve and is connected to an inlet of the gas-liquid separator, when the single-cylinder operation is switched to the double-cylinder operation, the high-pressure coolant at the suction port of the lower cylinder is decompressed to the inlet of the gas-liquid separator via the capillary pipe, the low-pressure coolant is formed at the suction port of the lower cylinder, and switching easily succeeds. However, since the capillary pipe flows for a long time, circulating coolants will be reduced accordingly so as to cause a heat loss.

It is noted that European patent publication EP 1 655 492 A1 discloses a rotary-type enclosed compressor and a refrigeration cycle apparatus wherein a vane of a first cylinder is compressed and urged by a spring member. A vane of a second cylinder is compressed and urged corresponding to a differential pressure between an intra-casing pressure guided into a vane chamber and a suction pressure or discharge pressure guided to the cylinder chamber. A pressure shift mechanism which guides the suction pressure or discharge pressure has a branch pipe having a one end connected to a high pressure side of the refrigeration cycle, an other end connected to a suction pipe, and a first on-off valve in a midway portion, and a second on-off valve or a check valve which is provided in the suction pipe on a side upstream of a connection portion of the branch pipe and on a side downstream of an oil returning opening in an accumulator.

Summary of the invention

The disclosure mainly aims to provide an air-conditioning system and a method for controlling an air-conditioning system, which are intended to solve the problem in the prior art that switching easily fails in a process of switching a single-cylinder operation and a double-cylinder operation of a compressor of the air-conditioning system.
In order to achieve the aim, according to an aspect of the disclosure, an air-conditioning system is provided, which comprise a double-cylinder capacity-variable compressor, the double-cylinder capacity-variable compressor having a suction port of an upper cylinder, a suction port of a lower cylinder and an exhaust port. The air-conditioning system may further comprise a first solenoid valve. One end of the first solenoid valve may be connected to the exhaust port of the double-cylinder capacity-variable compressor, and the other end of the first solenoid valve may be connected to a one-way valve and the suction port of the lower cylinder of the double-cylinder capacity-variable compressor respectively. One end of the one-way valve may be connected to the first solenoid valve, and the other end of the one-way valve may be communicated with an inner chamber of a gas-liquid separator. The air-conditioning system may further comprise a second solenoid valve, provided in a pipeline connecting the suction port of the lower cylinder of the double-cylinder capacity-variable compressor to an inlet of the gas-liquid separator.
Furthermore, the air-conditioning system may further comprise a capillary pipe, connected in series to the second solenoid valve.
Furthermore, the air-conditioning system may further comprise a temperature sensor, provided in a pipeline of the suction port of the lower cylinder.
Furthermore, the air-conditioning system may further comprise a high-pressure sensor, provided in a pipeline of the exhaust port.
According to another aspect of the disclosure, a method for controlling an air-conditioning system is provided, which may be applied to the air-conditioning system. The control method comprise that: Step 10, when a double-cylinder capacity-variable compressor is under a single-cylinder operation state and is required to be switched to a double-cylinder operation state, a pipeline connecting a suction port of a lower cylinder of the double-cylinder capacity-variable compressor to an inlet of a gas-liquid separator is opened.
Furthermore, in the Step 10, the pipeline connecting the suction port of the lower cylinder of the double-cylinder capacity-variable compressor to the inlet of the gas-liquid separator is opened via a second solenoid valve, and a first solenoid valve may be closed after a period of time ts.
Furthermore, the control method further comprise that: Step 20, when the double-cylinder capacity-variable compressor has been under the single-cylinder operation state for over a period of time t1, a temperature T_lower of the suction port of the lower cylinder of the double-cylinder capacity-variable compressor and a temperature T_high of an exhaust port of the double-cylinder capacity-variable compressor are compared at a time interval of t2, and if T_lower is smaller than or equal to T_high, the second solenoid valve is closed after having been opened for a period of time t3.
Furthermore, the time ts in the Step 10 may be relevant to an outdoor environment temperature TW. When TW is greater than or equal to A°C, ts may be equal to t5, when TW is greater than or equal to B°C and is smaller than A°C, ts may be equal to t6, and when TW is smaller than B°C, ts may be equal to t7, where t5, t6 and t7 may be pre-set time constants, and A and B may be pre-set temperature constants.
Furthermore, the Step 10 may further comprise that: the second solenoid valve is closed after the first solenoid valve has been closed for a period of time t4.
By means of the technical solutions, a drain bypass pipeline provided with a solenoid valve is additionally provided between the suction port of the lower cylinder and the inlet of the gas-liquid separator, and a high-pressure coolant at a suction side of the lower cylinder is decompressed to the gas-liquid separator via the drain bypass pipeline, thereby optimizing the stability of the system when being switched from the single-cylinder operation to the double-cylinder operation.

Brief description of the drawings

The specification drawings forming a part of the disclosure are intended to provide further understanding of the disclosure. The schematic embodiments and descriptions of the disclosure are intended to explain the disclosure, and do not form improper limits to the disclosure. In the drawings:

Fig. 1 shows an air-conditioning system with a capacity-variable and frequency-variable compressor in the prior art;
Fig. 2 shows an air-conditioning system according to the disclosure; and
Fig. 3 shows a flowchart of a control method of th air-conditioning system according to the disclosure.

Detailed description of the embodiments

It is important to note that the embodiments of the disclosure and the characteristics in the embodiments can be combined under the condition of no conflicts. The disclosure is described below with reference to the drawings and the embodiments in detail.
As shown in Fig. 2, according to the disclosure, on the basis of the prior art, a drain bypass pipeline is additionally provided between a suction port of a lower cylinder of a double-cylinder capacity-variable compressor and an inlet of a gas-liquid separator. The drain bypass pipeline mainly comprises a capillary pipe and a second solenoid valve 72, a high-pressure sensor 100 is additionally provided at an exhaust side of the double-cylinder capacity-variable compressor to detect a condensation temperature T_high, and a temperature sensor 90 is additionally provided at the suction port of the lower cylinder and serves as a detection tool for detecting a temperature T_lower of the suction port of the lower cylinder. Under a specific condition, the second solenoid valve 72 of the drain bypass pipeline is opened so as to conduct decompression and drain motions. When the suction port of the lower cylinder is under a liquid collection state, a liquid-state coolant on a connecting pipe between the lower cylinder of the double-cylinder capacity-variable compressor 30 and a first solenoid valve 71 can be discharged to the gas-liquid separator by means of automatic detection. When a single-cylinder operation is switched to a double-cylinder operation, a high-pressure coolant at a suction side of the lower cylinder is decompressed to the gas-liquid separator via the drain bypass pipeline, so as to the single-cylinder operation is successfully switched to the double-cylinder operation, thereby improving the stability of the system when switched operation.
As shown in Fig. 2, an air-conditioning system according to the disclosure comprises the double-cylinder capacity-variable compressor 30 and the gas-liquid separator. A suction port of an upper cylinder, the suction port of the lower cylinder and an exhaust port are led out of the double-cylinder capacity-variable compressor 30. The double-cylinder capacity-variable compressor 30, a first heat exchanger 10, a throttling assembly 40 and a second heat exchanger 20 are connected to form a loop. The air-conditioning system further comprises a four-way valve 60, the first solenoid valve 71 and a one-way valve 50. The first heat exchanger 10 and the second heat exchanger 20 are selectively connected to the double-cylinder capacity-variable compressor 30 via the four-way valve 60; one end of the first solenoid valve 71 is connected to the exhaust port of the double-cylinder capacity-variable compressor 30, and the other end of the first solenoid valve 71 is connected to the one-way valve 50 and the suction port of the lower cylinder respectively; one end of the one-way valve 50 is connected to a pipeline, the pipeline from the first solenoid valve 71 leading to the suction port of the lower cylinder, and the other end of the one-way valve 50 is communicated with an inner chamber of the gas-liquid separator; and the one-way valve 50 is allowed to flow from the gas-liquid separator to the suction port of the lower cylinder. In the disclosure, a branch formed by the second solenoid valve 72 and the capillary pipe connected in series thereto is additionally provided and is connected between a pipeline of the suction port of the lower cylinder of the compressor and a pipeline of the inlet of the gas-liquid separator.
The capillary pipe in a drain bypass loop has a function of controlling the drain flow. If a capillary pipe is too thick and too short, the flow will be over-high, the pressure reduction of the lower cylinder will be caused, and the single-cylinder operation cannot be continued in case of pressure shortage and will be switched to the double-cylinder operation. If a capillary pipe is too thin and too long, the flow will be over-low, a drain speed will be too low, and the drain motion cannot be completed within a set time. Thus, a moderate capillary pipe is needed for the drain bypass loop.
As shown in Fig. 3, a method for controlling an air-conditioning system according to the disclosure comprises:

(1) When a double-cylinder capacity-variable compressor 30 is under single-cylinder operation and the single-cylinder operation time of the double-cylinder capacity-variable compressor 30 exceeds a period of time t1, T_lower and T_high are compared at a time interval of t2, and if T_lower is smaller than or equal to T_high, it is judged that liquid is collected on a pipeline of the suction port of the lower cylinder of the air-conditioning system, and a second solenoid valve 72 is closed after having been opened for a period of time t3 so as to achieve an interval drain effect.
(2) When the double-cylinder capacity-variable compressor 30 is under the single-cylinder operation and is required to be switched to double-cylinder operation, a first solenoid valve 71 is closed after the second solenoid valve 72 has been opened for a period of time ts, and the second solenoid valve 72 is closed after the first solenoid valve 71 has been closed for a period of time t4 so as to achieve a decompression effect.
(3) Since the liquid collection situations of different outdoor environment temperatures TW are different, the time ts in Step (2) is relevant to the outdoor environment temperatures. For example, (A and B are pre-set temperature constants which can be determined via experiments)
1. a) when TW is greater than or equal to A°C, ts is equal to t5;
2. b) when TW is greater than or equal to B°C and is smaller than A°C, ts is equal to t6; and
3. c) when TW is smaller than B°C, ts is equal to t7. (where t1, t2, t3, t4, t5, t6 and t7 are pre-set time which can be determined via experiments.)

In the disclosure, a refrigerating/heating capacity adjustment range of the system is expanded by the combination of a double-cylinder or multi-cylinder frequency-variable compressor with the gas-liquid separator and a capacity variation technology. The bypass branch formed by the second solenoid valve and the capillary pipe has main functions as follows. When it is necessary to close the first solenoid valve, the second solenoid valve is opened to reduce the pressure of the pipeline between the suction port of the lower cylinder and the first solenoid valve to be consistent with low pressure so as to ensure that the compressor is quickly switched to be under double-cylinder operation after the first solenoid valve is closed. When the air-conditioning system is under the single-cylinder operation, it can be judged whether liquid is collected at the suction port of the lower cylinder by means of temperature detected by a pipeline temperature sensor at the suction port of the lower cylinder of the compressor and high-pressure temperature detected by a high-pressure sensor. When the liquid collection is judged, the second solenoid valve is opened for a period of time, so that the effect of preventing a liquid impact when the compressor is switched from the single-cylinder operation to the double-cylinder operation after the single-cylinder operation lasts long.
The above is only the preferred embodiments of the disclosure, and is not intended to limit the disclosure. There can be various modifications and variations in the disclosure for those skilled in the art. Any modifications, equivalent replacements, improvements and the like shall fall within the scope of protection defined by the appended claims.

Claims

An air-conditioning system, comprising a double-cylinder capacity-variable compressor (30), the double-cylinder capacity-variable compressor (30) having a suction port of an upper cylinder, a suction port of a lower cylinder and an exhaust port, and the air-conditioning system further comprising a first solenoid valve (71), one end of the first solenoid valve (71) is connected to the exhaust port of the double-cylinder capacity-variable compressor (30), and the other end of the first solenoid valve (71) is connected to a one-way valve (50) and the suction port of the lower cylinder of the double-cylinder capacity-variable compressor (30) respectively; one end of the one-way valve (50) is connected to the first solenoid valve (71), and the other end of the one-way valve (50) is communicated with an inner chamber of a gas-liquid separator; wherein
the air-conditioning system further comprises a second solenoid valve (72), provided in a pipeline connecting the suction port of the lower cylinder of the double-cylinder capacity-variable compressor (30) to an inlet of the gas-liquid separator.
The air-conditioning system according to claim 1, wherein further comprising a capillary pipe, connected in series to the second solenoid valve (72).
The air-conditioning system according to claim 1, wherein further comprising a temperature sensor (90), provided in a pipeline of the suction port of the lower cylinder.
The air-conditioning system according to claim 1, wherein further comprising a high-pressure sensor (100), provided in a pipeline of the exhaust port.
A method for controlling an air-conditioning system, wherein applied to an air-conditioning system according to any one of claims 1 to 4, the control method comprising: Step 10, when a double-cylinder capacity-variable compressor (30) is under a single-cylinder operation state and is required to be switched to a double-cylinder operation state, opening a pipeline connecting a suction port of a lower cylinder of the double-cylinder capacity-variable compressor (30) to an inlet of a gas-liquid separator.
The method for controlling an air-conditioning system according to claim 5, wherein in the Step 10, the pipeline connecting the suction port of the lower cylinder of the double-cylinder capacity-variable compressor (30) to the inlet of the gas-liquid separator is opened via a second solenoid valve (72), and a first solenoid valve (71) is closed after a period of time ts.
The method for controlling an air-conditioning system according to claim 6, wherein the control method further comprising: Step 20, when the double-cylinder capacity-variable compressor (30) has been under the single-cylinder operation state for over a period of time t1, comparing a temperature T_lower of the suction port of the lower cylinder of the double-cylinder capacity-variable compressor (30) with a temperature T_high of an exhaust port of the double-cylinder capacity-variable compressor (30) at a time interval of t2, and if T_lower is smaller than or equal to T_high, closing the second solenoid valve (72) after having been opened for a period of time t3.
The method for controlling an air-conditioning system according to claim 6, wherein the time ts in the Step 10 is relevant to an outdoor environment temperature TW; and when TW is greater than or equal to A°C, ts is equal to t5, when TW is greater than or equal to B°C and is smaller than A°C, ts is equal to t6, and when TW is smaller than B°C, ts is equal to t7, wherein t5, t6 and t7 are pre-set time constants, and A and B are pre-set temperature constants.
The method for controlling an air-conditioning system according to claim 6, wherein the Step 10 further comprises: closing the second solenoid valve (72) after the first solenoid valve (71) has been closed for a period of time t4.