EP2354724A2

EP2354724A2 - Air conditioner and method for controlling air conditioner

Info

Publication number: EP2354724A2
Application number: EP11153578A
Authority: EP
Inventors: Kiback Kwon; Sunghwan Kim
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2010-02-08
Filing date: 2011-02-07
Publication date: 2011-08-10
Anticipated expiration: 2031-02-07
Also published as: EP2354724B1; CN102147142B; KR20110092072A; CN102147142A; EP2354724A3; KR101155345B1

Abstract

Provided are an air conditioner, which detects refrigerant leak in real time, and a method for controlling the air conditioner. The method for controlling an air conditioner includes: tracking a cycle change from operating variables of the air conditioner; detecting refrigerant leak from the cycle change; and representing result of the detecting refrigerant leak.

Description

The present invention relates to an air conditioner and a method for controlling the air conditioner, and more particularly, to an air conditioner, which detects refrigerant leak in real time, and a method for controlling the air conditioner.
An air conditioner refers to a device for adjusting the condition of air to keep the air in a certain space in a condition which makes it comfortable to live in. Such an air conditioner functions to absorb heat within a certain space or release heat to the space so that the temperature and humidity of the space are kept at a proper level. The air conditioner of this type necessarily needs an indoor unit for absorbing heat within a certain space or releasing heat to the space.
To detect refrigerant leak, it has been necessary for a service engineer to visit the site and comprehensively check the operation status of the air conditioner before detecting the refrigerant leak.
It is an object of the present invention to provide an air conditioner, which detects refrigerant leak in real time by self-monitoring, and a method for controlling the air conditioner.
It is another object of the present invention to provide an air conditioner, which increases the accuracy of detection of refrigerant leak and prevents environmental contamination and additional failures caused by refrigerant leak, and a method for controlling the air conditioner.
The objects of the present invention are not limited by the above-described objects, and other objects that are not mentioned will be apparent to those skilled in the art from the description that follows.
To accomplish the above objects, there is provided a method for controlling an air conditioner according to an exemplary embodiment of the present invention, the method including: tracking a cycle change from operating variables of the air conditioner; detecting refrigerant leak from the cycle change; and representing result of the detecting refrigerant leak.
To accomplish the above objects, there is provided an air conditioner according to an exemplary embodiment of the present invention, including: an outdoor unit for condensing refrigerant and exchanging heat with outdoor air; an indoor unit connected to the outdoor unit and for exchanging heat with indoor air; and a control unit for detecting refrigerant leak from operating variables measured by the outdoor unit and the indoor unit, and representing result of the detecting refrigerant leak.
Details of other exemplary embodiments are included in the detailed description and drawings.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

FIG. 1 is a configuration diagram of an air conditioner according to an exemplary embodiment of the present invention;
FIG. 2 is a block diagram of the air conditioner according to an exemplary embodiment of the present invention;
FIG. 3 is a view showing a P-H diagram of the air conditioner according to an exemplary embodiment of the present invention; and
FIG. 4 is a flowchart showing a method for controlling an air conditioner according to an exemplary embodiment of the present invention.

Advantages and features of the present invention and methods of accomplishing the same will become apparent and more readily appreciated from the following description of the embodiments in conjunction with the accompanying drawings. The present invention may, however, may be embodied in many different forms, and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. Like reference numerals refer to like elements throughout the specification.
Hereinafter, an air conditioner and a method for controlling the air conditioner according to exemplary embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an air conditioner according to an exemplary embodiment of the present invention.
The air conditioner according to the exemplary embodiment of the present invention comprises an outdoor unit OU and a plurality of indoor units IUs.
The outdoor unit OU comprises a compressor 110, an outdoor heat exchanger 140, an outdoor expansion valve 132, and a super cooler 180. The air conditioner may comprise one or a plurality of outdoor units OUs, and one outdoor unit OU is provided in this exemplary embodiment.
The compressor 110 compresses an incoming low-temperature low-pressure refrigerant into a high-temperature high-pressure refrigerant. The compressor 110 may have various structures, and an inverter type compressor or constant-speed compressor may be employed. A discharge temperature sensor 171 and a discharge pressure sensor 151 are installed on a discharge pipe 161 of the compressor 110. A suction temperature sensor 175 and a suction pressure sensor 154 are installed on a suction pipe 168 of the compressor 110.
The outdoor unit OU is shown to have one compressor 110, but without being limited thereto, the outdoor unit OU of the present invention may comprise a plurality of compressors, including both an inverter type compressor and a constant-speed compressor.
An accumulator 187 may be installed at the suction pipe 168 of the compressor 110 to prevent a liquid refrigerant from being introduced into the compressor 110. Further, an oil separator 113 may be installed at the discharge pipe 161 of the compressor 110 to collect oil in the refrigerant discharged from the compressor 110.
A four-way valve 160 is a flow switching valve to switch between cooling and heating operations. The four-way valve 160 guides the refrigerant, compressed by the compressor 110, to the outdoor heat exchanger 140 during the cooling operation, and to an indoor heat exchanger 120 during the heating operation. The four-way valve 160 is in an A state in the cooling operation, and is in a B state in the heating operation.
The outdoor heat exchanger 140 is disposed in an outdoor space, and the refrigerant passing through the outdoor heat exchanger 140 exchanges heat with outdoor air. The outdoor heat exchanger 140 serves as a condenser in the cooling operation and serves as an evaporator in the heating operation.
An outdoor outlet temperature sensor 179 is installed on an inlet pipe 166 connecting a liquid pipe 165 and the outdoor heat exchanger 140.
The outdoor expansion valve 132 throttles the incoming refrigerant flow in the heating operation, and is installed on the inlet pipe 166. Further, a first bypass pipe 167 to allow the refrigerant to bypass the outdoor expansion valve 132 is installed on the inlet pipe 166, and a check valve 133 is installed on the first bypass pipe 167 to allow refrigerant to only flow in one direction. The check valve 133 causes the refrigerant to flow from the outdoor heat exchanger 140 to the plurality of indoor units IUs in the cooling operation, but shuts off the flow of the refrigerant in the heating operation.
The supercooler 180 includes a supercooling heat exchanger 184, a second bypass pipe 181, a supercooling expansion valve 182, and a discharge pipe 185. The supercooling heat exchanger 184 is disposed on the inlet pipe 166. In the cooling operation, the second bypass pipe 181 serves to cause the refrigerant discharged from the supercooling heat exchanger 184 to be fed into the supercooling expansion valve 182.
The supercooling expansion valve 182 is disposed on the second bypass pipe 181. The supercooling expansion valve 182 throttles the refrigerant flow in a liquid state fed into the second bypass pipe 181 to lower the pressure and temperature of the refrigerant, and then feeds the refrigerant in the low-pressure and low-temperature state into the supercooling heat exchanger 184. The supercooling expansion valve 182 may employ various types of valves, but the present embodiment employs a linear expansion valve for convenience of use. A supercooler inlet temperature sensor 177 to measure the temperature of the refrigerant throtteld by the supercooling expansion valve 182 may be installed on the second bypass pipe 181.
During the cooling operation, the condensed refrigerant passing through the outdoor heat exchanger 140 is supercooled by exchanging heat with the refrigerant in the low-temperature state fed through the second bypass pipe 181 in the supercooling heat exchanger 184, and then is fed to the plurality of indoor units IUs.
The refrigerant passing through the second bypass pipe 181 is fed to the accumulator 187 through the discharge pipe 185, after undergoing heat-exchange in the supercooling heat exchanger 184. A supercooler outlet temperature sensor 178 to measure the temperature of the refrigerant fed to the accumulator 187 is installed on the discharge pipe 185.
A liquid pipe temperature sensor 174 and a liquid pipe pressure sensor 156 are installed on the liquid pipe 165 connecting the supercooler 180 and the plurality of indoor units IUs.
In the air conditioner in accordance with an exemplary embodiment of the present invention, each of the plurality of indoor units IUs comprises an indoor heat exchanger 120, an indoor air blower 125, and an indoor expansion valve 131. The air conditioner may include one indoor unit IU or a plurality of indoor units IUs. In this exemplary embodiment, a plurality of IUs (1 to n) are provided.
The indoor heat exchanger 120 is disposed in an indoor space, and the refrigerant passing through the indoor heat exchanger 120 exchanges heat with indoor air. The indoor heat exchanger 120 serves as an evaporator in the cooling operation, and serves as a condenser in the heating operation.
The indoor air blower 125 blows indoor air that undergoes heat exchange in the indoor heat exchanger 120.
The indoor expansion valve 131 throttles the incoming refrigerant flow in the cooling operation. The indoor expansion valve 131 is installed on an indoor inlet pipe 163 of the indoor unit IU. The indoor expansion valve 131 may employ various types of valves, but the present embodiment employs a linear expansion valve for convenience of use.
Preferably, the indoor expansion valve 131 is opened to a set opening degree during the cooling operation, and is completely opened during the heating operation. The indoor expansion valve 131 may be closed during the blowing operation. Here, the closing of the indoor expansion valve 131 does not mean complete physical closing, but means an opening degree of the indoor expansion valve 131 such that the refrigerant does not flow through the indoor expansion valve 131. The indoor expansion valve 131 may be closed or opened in order to detect a malfunction.
An indoor inlet pipe temperature sensor 173 may be installed on the indoor inlet pipe 163. The indoor inlet pipe temperature sensor 173 may be installed between the indoor heat exchanger 120 and the indoor expansion valve 131. Further, an indoor outlet pipe temperature sensor 172 may be installed on an indoor outlet pipe 164.
The flow of the refrigerant during the cooling operation of the above-described air conditioner is as follows.
The refrigerant in a high-temperature and high-pressure vapor state discharged from the compressor 110 is fed into the outdoor heat exchanger 140 via the four-way valve 160. In the outdoor heat exchanger 140, the refrigerant exchanges heat with the outdoor air, thus being condensed. The refrigerant discharged from the outdoor heat exchanger 140 is fed to the supercooler 180 through the completely open outdoor expansion valve 132 and the bypass pipe 133. The refrigerant fed to the supercooler 180 is supercooled by the supercooling heat exchanger 184, and then is fed to the plurality of indoor units IUs.
A part of the refrigerant supercooled by the supercooling heat exchanger 184 is throttled by the supercooling expansion valve 182 to supercool the refrigerant passing through the supercooling heat exchanger 184. A part of the refrigerant supercooled by the supercooling heat exchanger 184 is fed to the accumulator 187.
The refrigerant fed to each of the indoor units IUs is throttled by the indoor expansion valve 131 that is open to a set opening degree, and the refrigerant is then evaporated by exchanging heat with the indoor air in the indoor heat exchanger 120. The evaporated refrigerant is then fed into the compressor 110 via the four-way valve 160 and the accumulator 187.
The flow of the refrigerant during the heating operation of the above-described air conditioner is as follows.
The refrigerant in a high-temperature and high-pressure vapor state discharged from the compressor 110 is fed into the plurality of indoor units IUs via the four-way valve 160. The indoor expansion valve 131 of each of the plurality of indoor units IUs is completely open. Therefore, the refrigerant fed from the indoor units IUs is throttled by the outdoor expansion valve 132, and then is evaporated by exchanging heat with outdoor air in the outdoor heat exchanger 140. The evaporated refrigerant is then fed into the suction pipe 168 of the compressor 110 via the four-way valve 160 and the accumulator 187.
FIG. 2 is a block diagram of the air conditioner according to an exemplary embodiment of the present invention.
The discharge temperature sensor 171 measures the temperature of the refrigerant discharged from the compressor 110. The discharge temperature sensor 171 is installed on the discharge pipe 161 of the compressor 110. A control unit 190 determines through the discharge temperature sensor 171 whether or not a high-pressure condensation temperature has a normal value in a normal operating state.
The indoor outlet pipe temperature sensor 172 measures the temperature of the refrigerant discharged from the indoor heat exchanger 120. The indoor outlet pipe temperature sensor 172 is installed on the indoor outlet pipe 164. The control unit 190 determines through the indoor outlet pipe temperature sensor 172 whether or not a low-pressure evaporation temperature is normal in the normal operating state.
The indoor inlet pipe temperature sensor 173 measures the temperature of the refrigerant fed to the indoor heat exchanger 120. The indoor inlet pipe temperature sensor 173 is installed on the indoor inlet pipe 163 connecting the indoor heat exchanger 120 and the indoor expansion valve 131.
The control unit 190 determines through the indoor inlet pipe temperature sensor 173 whether or not an indoor inlet pipe temperature is normal in the normal operating state. Further, the control unit 190 calculates the difference between a temperature measured by the indoor outlet pipe temperatures sensor 172 and a temperature measured by the indoor inlet pipe temperature sensor 173 to determine whether or not the superheating degree of the indoor heat exchanger is normal in the normal operating state.
The liquid pipe temperature sensor 174 measures the temperature of the refrigerant flowing between the supercooler 180 and the indoor heat exchanger 120. The liquid pipe temperature sensor 174 is installed on the liquid pipe 165 connecting the supercooler 180 and the indoor units IUs. The control unit 190 determines through the liquid pipe temperature sensor 174 whether or not a liquid pipe temperature is normal in the normal operating state.
The suction temperature sensor 175 measures the temperature of the refrigerant sucked into the compressor 110. The suction temperature sensor 175 is installed on the suction pipe 168 of the compressor 110. The control unit 190 determines through the suction temperature sensor 175 whether or not a suction temperature is normal in the normal operating state.
The supercooler inlet temperature sensor 177 measures the temperature of the refrigerant throttled for supercooling in the supercooler 180. The supercooler inlet temperature sensor 177 is installed on the second bypass pipe 181. The supercooler outlet temperature sensor 178 measures the temperature of the refrigerant heat-exchanged after being throttled for supercooling in the supercooler 180. The supercooler outlet temperature sensor 178 is installed on the discharge pipe 185. The control unit 190 calculates the difference between a temperature measured by the supercooler inlet temperature sensor 177 and a temperature measured by the supercooler outlet temperature sensor 178 to determine whether or not the superheating degree of a supercooling circuit is normal in the normal operating state.
The outdoor outlet temperature sensor 179 measures the temperature of the refrigerant to be condensed in the outdoor heat exchanger 140 during the cooling operation or to be evaporated in the outdoor heat exchanger 140 during the heating operation. The outdoor outlet temperature sensor 179 is installed on the inlet pipe 166. The control unit 190 determines through the outdoor outlet temperature sensor 179 whether or not an outdoor heat exchanger outlet temperature is normal in the normal operating state.
An opening degree of the indoor expansion valve 131 is transmitted to the control unit 190 so that the control unit 190 determines whether or not the opening degree of the indoor expansion valve is normal in the normal operating state.
An opening degree of the supercooling expansion valve 182 is transmitted to the control unit 190 so that the control unit 190 determines whether or not the opening degree of the supercooling expansion valve is normal in the normal operating state.
The high-pressure pressure sensor 151 measures the pressure of the refrigerant discharged from the compressor 110. The high-pressure sensor 151 is installed on the discharge pipe 161 of the compressor 110. The control unit 190 determines through the high-pressure sensor 151 whether or not a discharge superheating degree has a normal value in the normal operating state by calculating the saturation temperature of the discharged refrigerant and calculating the difference with the discharge temperature measured by the discharge temperature sensor 171.
The low-pressure sensor 154 measures the pressure of the refrigerant sucked into the compressor 110. The low-pressure sensor 154 is installed on the suction pipe 162 of the compressor 110. The control unit 190 determines through the low-pressure sensor 154 whether or not a suction superheating degree is normal in the normal operating state by calculating the saturation temperature of the sucked refrigerant and calculating the difference with the suction temperature measured by the suction temperature sensor 175.
The liquid pipe pressure sensor 156 measures the pressure of the refrigerant flowing between the supercooler 180 and the indoor heat exchanger 120. The liquid pipe pressure sensor 156 is installed on the liquid pipe 165 connecting the supercooler 180 and the indoor unit IU. The control unit 190 determines through the liquid pipe pressure sensor 156 whether or not a supercooling degree is normal in the normal operating state by calculating the saturation temperature of the supercooled refrigerant and calculating the difference with the liquid temperature measured by the liquid pipe temperature sensor 174.
The control unit 190 tracks a cycle change from operating variables measured in real time in the normal operating state to detect refrigerant leak from the cycle change. The operating variables include at least one of a suction superheating degree, a discharge superheating degree, an indoor inlet pipe temperature, a suction temperature, a condensation temperature, an evaporation temperature, a supercooling temperature, a liquid pipe temperature, the opening degree of the superheating expansion valve, the overheating degree of the supercooling circuit, the superheating degree of the indoor heat exchanger, and an outdoor heat exchanger outlet temperature. The normal operating state refers to a state where a general cooling or heating operation is performed normally by superheating degree control, rather than by start-up control or by direct control of the outdoor unit.
The control unit 190 tracks a change in cooling cycle or heating cycle from a change on a Pressure Enthalpy(P-H) diagram (Mollier diagram). Upon detecting refrigerant leak, the control unit 190 transmits the detection result to the display unit 192 or the communication unit 194 to notify the outside of this detection result.
The display unit 192 externally displays result of the detecting the refrigerant leak. The display unit 192 can aurally or visually represent refrigerant leak, preferably, visually displays the refrigerant leak by 7 segment or LED.
The communication unit 194 externally transmits result of the detecting the refrigerant leak via a network. The communication unit 194 transmits the result of the detecting the refrigerant leak to a control center or the terminal of a service engineer at a distance via the network and displays it.
FIG. 3 is a view showing a P-H diagram of the air conditioner according to an exemplary embodiment of the present invention.
In the P-H diagram, the cycle obtained at a normal refrigerant amount and the cycle obtained during refrigerant leak are different. Referring to FIG. 3, a method of determining the normality of a discharge superheating degree will be discussed. In FIG. 3, the discharge superheating degree at the normal refrigerant amount is T1, and the discharge superheating degree during the refrigerant leak is T2. That is, the normal value of the discharge superheating degree is T1.
The control unit 190 tracks whether or not the discharge superheating degree is T2 in the normal operating state to detect refrigerant leak.
FIG. 4 is a flowchart showing a method for controlling an air conditioner according to an exemplary embodiment of the present invention.
Operating variables are measured in the normal operating state (S210). The operating variables include at least one of a suction superheating degree, a discharge superheating degree, an indoor inlet pipe temperature, a suction temperature, a condensation temperature, an evaporation temperature, a supercooling temperature, a liquid pipe temperature, the opening degree of the superheating expansion valve, the overheating degree of the supercooling circuit, the superheating degree of the indoor heat exchanger, and an outdoor heat exchanger outlet temperature. The normal operating state refers to a state where a general cooling or heating operation is performed normally by means of superheating degree control, rather than by means of start-up control or direct control of the outdoor unit.
A cycle change is tracked from the operating variables to detect refrigerant leak (S220). The control unit 190 determines normality by tracking a change in cooling cycle or heating cycle from a change on the P-H diagram.
If refrigerant leak is detected, it is determined whether or not a self-supercooling degree of the outdoor heat exchanger attains a reference value (S230). The self-supercooling degree of the outdoor heat exchanger is the difference between a condensation temperature measured by the discharge temperature sensor 171 and an outdoor heat exchanger outlet temperature measured by the outdoor outlet temperature sensor 179. If there is any refrigerant left in the accumulator 187, this can be considered as refrigerant leak, and therefore the control unit 190 determines whether or not the self-supercooling degree of the outdoor heat exchanger attains the reference value.
If the self-supercooling degree of the outdoor heat exchanger attains the reference value, the control unit 190 measures the operating variables again in the normal operating state (S270).
If the self-supercooling degree of the outdoor heat exchanger does not attain the reference value, a target superheating degree of the indoor heat exchanger is increased (S240). The superheating degree of the indoor heat exchanger is the difference between a temperature measured by the indoor outlet pipe temperature sensor 172 and a temperature measured by the indoor inlet pipe temperature sensor 173. The control unit 190 increases the target superheating degree of the indoor heat exchanger to empty the refrigerant left in the accumulator 187.
After increasing the target superheating degree of the indoor heat exchanger, the timer is increased (S250), and the control unit 190 determines if the timer exceeds a reference time (S260). If the timer does not exceed the reference time, the control unit 190 determines whether or not the self-supercooling degree of the outdoor heat exchanger attains the reference value (S230).
If the timer exceeds the reference time, the operating variables are measured again in the normal operating state (S270), and a cycle change is tracked from the operating variables to detect t refrigerant leak again (S280). The control unit 190 increases accuracy by detecting the refrigerant leak once again.
If refrigerant leak is detected, a refrigerant leak state is displayed or transmitted (S290). Upon detecting refrigerant leak, the control unit 190 transmits the detection result to the display unit 192 or the communication unit 194 to represent result of the detecting refrigerant leak. The display unit 192 externally displays the result of the detecting refrigerant leak. The communication unit 194 externally transmits the result of the detecting refrigerant leak via a network.
As aforementioned, the preferred embodiment of the present invention has been shown and described, but the present invention is not limited to the specific embodiments described above, and can be implemented in various modifications by those skilled in the art to which the present invention pertains without departing from the scope of the present invention recited in the appended claims, and such modifications should not be understood to depart from the technical spirit or prospect of the present invention.
According to the air conditioner and the method for controlling the air conditioner of the present invention, one or more of the following effects can be observed.
First, refrigerant leak can be detected in real time by self-monitoring of the air conditioner.
Second, the accuracy of detection of refrigerant leak of the air conditioner can be increased.
Third, refrigerant leak of the air conditioner can be quickly detected, thereby preventing additional failures and minimizing environmental contamination.

Claims

A method for controlling an air conditioner, the method comprising:
tracking a cycle change from operating variables of the air conditioner;

detecting refrigerant leak from the cycle change; and

representing result of the detecting refrigerant leak.
The method of claim 1, wherein the operating variables include at least one of a suction superheating degree, a discharge superheating degree, an indoor inlet pipe temperature, a suction temperature, a condensation temperature, an evaporation temperature, a supercooling temperature, a liquid pipe temperature, the opening degree of the superheating expansion valve, the overheating degree of the supercooling circuit, the superheating degree of the indoor heat exchanger, and an outdoor heat exchanger outlet temperature.
The method of claim 1 or 2, wherein the cycle change is tracked in a normal operating state.
The method of claim 1 or 2, wherein the cycle change is a change on a Pressure Enthalpy(P-H) diagram.
The method of any of claims 1 to 4, wherein the result of the detecting refrigerant leak is displayed on the air conditioner.
The method of any of claims 1 to 5, wherein the result of the detecting refrigerant leak is transmitted via a network.
The method of any of claims 1 to 6, further comprising:
determining whether or not a self-supercooling degree of the outdoor heat exchanger attains a reference value when refrigerant leak is detected;

increasing a target superheating degree of the indoor heat exchanger of the air conditioner when the self-supercooling degree attains the reference value; and

detecting refrigerant leak again.
An air conditioner, comprising:
an outdoor unit for condensing refrigerant and exchanging heat with outdoor air;

an indoor unit connected to the outdoor unit and for exchanging heat with indoor air; and

a control unit for detecting refrigerant leak from operating variables measured by the outdoor unit and the indoor unit, and representing result of the detecting refrigerant leak.
The air conditioner of claim 8, wherein the operating variables include at least one of a suction superheating degree, a discharge superheating degree, an indoor inlet pipe temperature, a suction temperature, a condensation temperature, an evaporation temperature, a supercooling temperature, a liquid pipe temperature, the opening degree of the superheating expansion valve, the overheating degree of the supercooling circuit, the superheating degree of the indoor heat exchanger, and an outdoor heat exchanger outlet temperature.
The air conditioner of claim 8 or 9, wherein the control unit detects the refrigerant leak from a cycle change.
The air conditioner of claim 8 or 9, further comprising a display unit for displaying the refrigerant leak detected by the control unit.
The air conditioner of any of claims 8 to 11, further comprising a communication unit for transmitting the refrigerant leak detected by the control unit via a network.
The air conditioner of any of claims 8 to 12, wherein the control unit determines whether or not a self-supercooling degree of the outdoor heat exchanger of the outdoor unit attains a reference value and increases a target superheating degree of the indoor heat exchanger of the indoor unit.