Method for controlling stop operation of air conditioner

Abstract

A method for controlling a stop operation of an air conditioner having a compressor, a four-way valve, an electronic expansion valve (EEV), an indoor fan and an outdoor fan includes the steps of stopping the operations of the compressor and the indoor fan if an operation stop signal is inputted during a heating operation; and checking an amount of elapsed time after the turn-offs of the compressor and the indoor fan, and turning off the EEV and the outdoor fan if the amount of elapsed time reaches a preset reference time. The methods also includes the steps of detecting pressures at an inlet side and at an outlet side of the compressor to calculate a pressure difference; and turning off the four-way valve if the calculated pressure difference reaches a preset reference pressure difference.

Description

FIELD OF THE INVENTION

The present invention relates to an operation control method of an air conditioner, and specifically, to a stop operation control method of an air conditioner, which is suitable for controlling the stop operation based on the inner environment (pressure or temperature) of an air conditioner at the time of stopping the air conditioner in a heating operation mode.

BACKGROUND OF THE INVENTION

As well-known in the art, a typical air conditioner has a structure as shown in FIG. 1 as one example.

Referring to FIG. 1, the typical air conditioner is largely divided into an outdoor unit 110 and an indoor unit 120. The outdoor unit 110 is constituted by a compressor 111, a four-way valve 112, an outdoor heat exchanger 113, an electronic expansion valve (EEV) 114, an accumulator 115, an outdoor fan 116, and any other items obvious to one skilled in the art for this application. The indoor unit 120 is constituted by an indoor heat exchanger 121, an indoor fan 123, and so forth.

During a cooling operation of the air conditioner with the typical structure described above, a high temperature, high pressure gaseous refrigerant compressed in the compressor 111 is introduced, via the four-way valve 112, into the outdoor heat exchanger 113 that functions as a condenser. This high pressure gaseous refrigerant undergoes a heat exchange, through the outdoor heat exchanger 113, with outdoor air of outdoor temperature which is lower than the refrigerant temperature, to be condensed to a high pressure state. Here, the outdoor fan 116 is driven by an outdoor fan motor (not shown), and serves to forcibly ventilate the outdoor air.

As the gaseous refrigerant condensed to high pressure passes through the EEV 114, it turns to low temperature, low pressure liquid refrigerant by throttling, and is conveyed to the indoor heat exchanger 121 of the indoor unit 120. Here, the indoor fan 123 is driven by an indoor fan motor (not shown), and serves to forcibly ventilate the indoor air.

Next, the refrigerant in a liquid state is evaporated through the heat exchange with indoor air at the indoor heat exchanger 121 functioning as an evaporator. After evaporation, the low temperature, low pressure gaseous refrigerant flows back to the outdoor unit 110 along a circulation line, in which it passes through the four-way valve 112 and is introduced again into the compressor 111 via the accumulator 115. Here, in the accumulator 115, the refrigerant having been introduced into the compressor 111 changes completely into gas.

Moreover, during a heating operation of the air conditioner with the typical structure described above, the direction of the refrigerant at the four-way valve 112 is reversed, thus, the refrigerant flows in opposite direction from the refrigerant flow during the cooling operation mentioned above. At this time, since the indoor heat exchanger 121 functions as a condenser differently from the cooling operation, warm air is circulated again into the indoor environment by the indoor fan 123. That is, the refrigerant flow during the heating operation of the air conditioner follows the circulation line, such as, the compressor 111->the four-way valve 112->the indoor heat exchanger 121->the EEV 114->the outdoor heat exchanger 113->the four-way valve 112->the accumulator 115->the compressor 111.

Meanwhile, the air conditioner with the refrigerant circulation line described above is set up in such a way that the position of the four-way valve automatically returns to a position for cooling operation if the air conditioner that had been in heating mode stops running.

As well-known in the art, when the air conditioner is in the heating mode, the inlet side of the compressor is at a relatively low pressure state, while the outlet side of the compressor is at a relatively high pressure state. If the air conditioner stops running in the heating mode, the pressure at the inlet side of the compressor slowly increases, while the pressure at the outlet side of the compressor slowly decreases, so that those pressures at the inlet and outlet sides of the compressor become gradually equalized for a long stretch of time.

Therefore, it is necessary to equalize the pressures on both sides (i.e., the inlet and the outlet) of the compressor more quickly. A conventional way to control the stop operation of an air conditioner was that when an operating stop signal is inputted in the middle of the heating operation, the compressor and the indoor fan were first turned off together, and the EEV, the outdoor fan and the four-way valve are also turned off after a specified amount of time has passed.

However, the simultaneous turn-offs of the EEV, the outdoor fan and the four-way valve as in the conventional way for the purpose of pressure equalization between the inlet side and the outlet side of the compressor could not resolve the problem completely because there was still a pressure difference above a certain level between the inlet side and the outlet side of the compressor. Consequently, when the four-way valve automatically returns to the position for cooling operation, an impact noise that sounds like “shook” is generated. This noise problem is now at issue as customer complains.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a method for controlling a stop operation of an air conditioner, capable of preventing an impact noise at a four-way valve due to a difference in pressure that occurs when the four-way valve automatically returns to a position for cooling operation after a heating operation of the air conditioner stops.

In accordance with one aspect of the invention, there is provided a method for controlling a stop operation of an air conditioner having a compressor, a four-way valve, an electronic expansion valve (EEV), an indoor fan and an outdoor fan, the method including the steps of: turning off the compressor and the indoor fan if an operation stop signal is issued during a heating operation of the air conditioner; checking an amount of elapsed time and turning off the EVV and the outdoor fan if an amount of elapsed time after the turn-offs of the compressor and the indoor fan reaches a preset reference time; detecting pressures at an inlet side and at an outlet side of the compressor to calculate a pressure difference therebetween; and turning off the four-way valve if the calculated pressure difference reaches a preset reference pressure difference.

It is preferable that the preset reference pressure difference is about 3 mb.

In accordance with another aspect of the invention, there is provided a method for controlling a stop operation of an air conditioner including a condenser and an evaporator in a structure that a compressor, a four-way valve, an EEV, an indoor fan and an outdoor fan are physically connected to one another, the method including the steps of: turning off of the compressor and the indoor fan if an operation stop signal is issued during a heating operation of the air conditioner; turning off of the EVV and the outdoor fan, if the amount of elapsed time after the turn-offs of the compressor and the indoor fan reaches a preset reference time; detecting temperatures at the condenser and at the evaporator to calculate a temperature difference therebetween; and turning off of the four-way valve if the calculated temperature difference reaches a preset reference temperature difference.

It is preferable that the preset reference temperature difference is about 10° C.

In accordance with another aspect of the invention, there is provided an air conditioner capable of preventing an impact noise generated after the completion of a heating operation of the air conditioner, which comprises: a compressor; a four-way valve; an electronic expansion valve; an indoor fan; an outdoor fan; a first and a second pressure sensors for detecting pressures at an inlet side and at an outlet side of the compressor, respectively; and a controller for turning off the compressor and the indoor fan, turning off the electronic expansion valve and the outdoor fan in a preset reference time after the turn-offs of the compressor and the indoor fan, and turning off the four-way valve if the pressure difference between the inlet side and the outlet side of the compressor reaches a preset reference pressure difference.

In accordance with still another aspect of the invention, there is provided an air conditioner capable of preventing an impact noise generated after the completion of a heating operation of the air conditioner, which includes: a compressor; a four-way valve; an electronic expansion valve; an indoor fan; an outdoor fan; a condenser; an evaporator; a first and a second temperature sensors for detecting temperatures at the condenser and at the evaporator, respectively; and a controller for turning off the compressor and the indoor fan, turning off the EEV and the outdoor fan, and turning off the four-way valve if the temperature difference between the condenser and the evaporator reaches a preset reference temperature difference.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments, given in conjunction with the accompanying drawings, in which:

FIG. 1 shows an overall structural view of a typical air conditioner system;

FIG. 2 illustrates a block diagram of an operation control apparatus of an air conditioner suitable for application of a method for controlling a stop operation of an air conditioner in accordance with a preferred embodiment of the present invention;

FIG. 3 provides a flowchart describing a procedure for the stop operation control of an air conditioner in accordance with a preferred embodiment of the present invention;

FIG. 4 illustrates a block diagram of an operation control apparatus of an air conditioner suitable for application of a method for controlling a stop operation of an air conditioner in accordance with another preferred embodiment of the present invention;

FIG. 5 offers a flowchart describing a procedure for the stop operation control of an air conditioner in accordance with another preferred embodiment of the present invention; and

FIG. 6 presents an example of a timing chart illustrating a procedure of stop operation control during a heating operation in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following description of the preferred embodiment, reference is made to accompanying drawings that form a part hereof and in which is shown by way of illustration a specific embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

Unlike the above-described conventional method for the stop operation control of an air conditioner in a heating mode which simultaneously turns off a compressor and an indoor fan first, and also turns off an EEV, an outdoor fan and a four-way valve after a specified amount of time elapses, in accordance with the technical gist of the present invention, in the present invention the compressor and the indoor fan are first turned off at the same time and the EEV and the outdoor fan are simultaneously turned off after a specified amount of time has passed. That is, in order to more easily accomplish the stop operation control of an air conditioner during the heating operation, the present invention suggests that a pressure difference between the inlet side and the outlet side of the compressor, or a temperature difference between a condenser and an evaporator should be detected after the simultaneous turn-offs of the EEV and the outdoor fan, and a turn-off time of the four-way valve should be decided based on the detection result (i.e., the pressure difference or the temperature difference).

First Embodiment

FIG. 2 is a schematic block diagram of an operation control apparatus of an air conditioner suitable for application of a method for controlling a stop operation of an air conditioner in accordance with one embodiment of the present invention. The operation control apparatus of an air conditioner includes an operating block 202, a first pressure sensor 204, a second pressure sensor 206, a control block 208, a compressor driving block 210, an EEV driving block 212, an indoor fan driving block 214, an outdoor fan driving block 216, and a four-way valve driving block 218.

Referring to FIG. 2, the operating block 202 is provided with a plurality of operation keys which allow a user to select the operation information of an air conditioner, such as power-on, operation mode (cooling operation mode, heating operation mode, etc.), specified temperature, air volume and the like. Various operation information generated by user input is forwarded to the control block 208.

The first pressure sensor 204 is installed at a designated position of the inlet side of a compressor 111 inside an outdoor unit 110 shown in FIG. 1 as one example, and detects pressure at the inlet side of the compressor. A pressure value detected at the inlet side of the compressor is sent to the control block 208 for the stop operation control under a heating operation in accordance with the present invention.

Likewise, the second pressure sensor 206 is installed at a designated position of the outlet side of a compressor 111 inside an outdoor unit 110 shown in FIG. 1 as one example, and detects pressure at the outlet side of the compressor. A pressure value detected at the outlet side of the compressor is delivered to the control block 208 for the stop operation control under a heating operation in accordance with the present invention.

The control block 208 includes, for example, a microprocessor, or any other device obvious to one skilled in the art for carrying out the similar task, so as to carry out the overall operational control of the air conditioner, which performs the control of the stop operation (time lag OFF control of a compressor, an indoor fan, an EEV, and an outdoor fan) when the air conditioner performs a heating operation, and the OFF control of the four-way valve based on a pressure difference between the inlet side and the outlet side of the compressor, and so on. More details will be provided later in reference to FIG. 3.

The compressor driving block 210 has functions for the ON/OFF control of the compressor 111, and the operation control of the compressor 111 at a specified operating frequency, and so on, which is in response to a compressor drive control signal that is provided from the control block 208. The EEV driving block 212 has functions for the adjustment of divergence of the EEV 114 shown in FIG. 1, and so on, in response to a divergence control signal that is also provided from the control block 208.

In addition, the indoor fan driving block 214 has a function for the operation control of the indoor fan 123 shown in FIG. 1, in response to an indoor fan drive control signal that is provided from the control block 208. The outdoor fan driving block 216 has a function for the operation control of the outdoor fan 116 shown in FIG. 1, in response to an outdoor fan drive control signal that is provided from the control block 208. Lastly, the four-way valve driving block 218 has a function for the operation control of the four-way valve 112 shown in FIG. 1, in response to a four-way valve drive control signal that is provided from the control block 208.

The following is a description for a stepwise procedure which carries out the stop operation control of an air conditioner according to the present invention using an operation control apparatus of the air conditioner having the above-described constitution.

FIG. 3 is a flowchart describing a procedure for the stop operation control of an air conditioner in accordance with an embodiment of the present invention.

Referring to FIG. 3, when the air conditioner is running in a heating mode according to operating conditions set by a user at step S302, the control block 208 checks at step S304 whether an operation stop signal according to user input has been received from the operating block 202.

In step S304, if the operation stop signal is received, the control block 208 generates a control signal for turning off the compressor 111 and a control signal for turning off the indoor fan 123 at the same time, and transfers the signals to the compressor driving block 210 and the indoor fan driving block 214, respectively. Consequently, the compressor 111 and the indoor fan 123 are turned off (or stop running) under the control of the compressor driving block 210 and the indoor fan driving block 214 at step S306.

Next, the control block 208 counts an elapsed time after the turn-off of the compressor 111, by using its internal timer (not shown), to check during step S308 if the elapsed time t1 has reached a preset reference time n1 (e.g., 1 minute).

In step S308, if the elapsed time t1 has reached a preset reference time n1, the control block 208 simultaneously generates control signals for turning off the EEV 114 and the outdoor fan 116, and transfers them to the EEV driving block 212 and the outdoor fan driving block 216, respectively. Consequently, the EEV 114 and the outdoor fan 116 stop running under the control of the EEV driving block 212 and the outdoor fan driving block 216 at step S310.

Thereafter, the control block 208 calculates a pressure difference between a pressure value at the inlet side of the compressor 111 detected which is provided by the first pressure sensor 204 and a pressure value at the outlet side of the compressor 111 detected which is provided by the second pressure sensor 206 at step S312, and compares the calculated pressure difference with a preset reference pressure difference (e.g., 3 mb), to thereby check at step S314 whether the calculated pressure difference has reached the reference pressure difference.

Here, it would be most ideal to equalize the pressures at the inlet and outlet sides of the compressor. In such a case, however, it takes too much time to get the pressure equalization at both sides. Taking this problem into consideration, the present invention suggests that the four-way valve should be turned off when the pressure difference between the inlet side and the outlet side of the compressor is about 3 mb.

In step S314, if the calculated pressure difference has reached the preset reference pressure difference, the control block 208 generates a corresponding control signal for turning off the four-way valve, and delivers the same to the four-way valve driving block 218. Consequently, the four-way valve 112 is turned off under the control of the four-way valve driving block 218, and thus, the heating operation of the air conditioner finally ends at step S316.

FIG. 6 shows an example of a timing chart illustrating the procedure of a stop operation control during the heating operation in accordance with the present invention. It is evident from the timing chart that the four-way valve is turned off after a preset amount of time (that is, at the time a pressure difference at the inlet side and the outlet side of the compressor has reached the preset reference pressure difference) has passed from the simultaneous turn-offs of the EEV and the outdoor fan.

To be short, unlike the conventional method for the stop operation control of an air conditioner in the heating mode which involves simultaneous turn-offs of an EEV, an outdoor fan, and a four-way valve, according to the method for the stop operation control of an air conditioner in accordance with the embodiment, the EEV and the outdoor fan are first turned off, and the four-way valve is then turned off only if a pressure difference at the inlet side and the outlet side of a compressor reaches a preset level (reference pressure difference). In this way, it becomes possible to effectively prevent an impact noise at the four-way valve due to the pressure difference caused when the four-way valve automatically returns to a position for cooling operation after the heating operation of an air conditioner stops.

Second Embodiment

FIG. 4 is a block diagram of an operation control apparatus of an air conditioner suitable for application of a method for controlling a stop operation of an air conditioner in accordance with another embodiment of the present invention. This invention operation control apparatus includes an operating block 402, a first temperature sensor 404, a second temperature sensor 406, a control block 408, a compressor driving block 410, an EEV driving block 412, an indoor fan driving block 414, an outdoor fan driving block 416, a four-way valve driving block 418 and the like.

Referring to FIG. 4, the components of the operation control apparatus of the second embodiment of the invention are substantially identical to those of the first embodiment shown in FIG. 2 in structure except that the second embodiment employs the first and the second temperature sensors 404 and 406, instead of the first and the second pressure sensors 204 and 206 used in the first embodiment. Thus, in order to avoid any redundant, repetitive description unnecessary for simplicity of the specification, details on functions of the same components with substantially identical functions will be omitted here.

Specifically, the first temperature sensor 404 is installed at, for example, a specified position of a pipe at a condenser side, and detects a temperature at the condenser side (that is, a temperature during the stop operation control). The temperature value detected at the condenser side is then sent to the control block 408 for the stop operation control in the heating mode according to the present invention.

Likewise, the second temperature sensor 406 is installed at, for example, a specified position of a pipe at an evaporator side, and detects a temperature at the evaporator side (that is, a temperature during the stop operation control). A temperature value detected at the evaporator side is then fed to the control block 408 for the stop operation control in the heating mode in accordance with the present invention.

Then, the control block 408 performs an operational control of the four-way valve in the stop mode based on a temperature difference at the condenser side and at the evaporator side, which is derived from the temperatures detected and provided by the first and the second temperature sensors 404 and 406. Further details on this control procedure will be provided below with reference to FIG. 5.

FIG. 5 is a flowchart describing the procedure for the stop operation control of an air conditioner in accordance with another embodiment of the present invention.

Referring to FIG. 5, steps from S502 to S510 (the figures do not correspond with figure numbers) in the procedure are substantially identical to steps S302 to S310 of FIG. 3 illustrated as the first embodiment. Therefore, to avoid any redundant, repetitive description unnecessary for simplicity of the specification, details on those steps will be omitted here.

At step S512, the compressor 111 and the indoor fan 123 are first turned off in response to an operation stop signal, and the EEV 114 and the outdoor fan 116 are also turned off after a preset time interval. Then, the first and the second temperature sensors 404 and 406 detect a temperature in the pipe at the condenser side and a temperature in the pipe at the evaporator side, respectively, and provide them to the control block 408. With these temperatures, the control block 408 calculates a temperature difference at the condenser side and at the evaporator side.

For instance, when an air conditioner is in a heating operation mode, the temperature at the condenser side usually ranges from about 40 to 44° C., and the temperature at the evaporator side ranges from about 12 to 18° C.

At a next step S514, the control block 408 compares a calculated temperature difference with a preset reference temperature difference (e.g., 10° C.), to check whether the calculated temperature difference has reached the reference temperature difference.

Although it would be most ideal to make the temperatures at the condenser side and at the evaporator side equalized, it would takes too much time. Taking this problem into consideration, the present invention suggests that the four-way valve should be turned off when the temperature difference between the condenser side and the evaporator side is around 10° C.

In step S514, if the calculated temperature difference has reached the preset reference temperature difference, the control block 408 generates a corresponding control signal for turning off the four-way valve, and delivers it to the four-way valve driving block 418. Consequently, the four-way valve 112 is turned off under the control of the four-way valve driving block 418, so that the heating operation of the air conditioner finally ends at step S516.

Even though the stop operation control method of this embodiment differs from the first embodiment in that a temperature difference at the condenser side and at the evaporator side is utilized, and not a pressures difference at the inlet and outlet sides of the compressor, both methods practically provide the same effects of impact noise prevention at the four-way valve due to a pressure difference that occurs when the four-way valve automatically returns to a position for cooling operation after the heating operation of an air conditioner stops.

As described above, unlike the above-described conventional method for the stop operation control of an air conditioner in a heating mode which simultaneously turns off a compressor and an indoor fan first, and also turns off an EEV, an outdoor fan and a four-way valve after a set amount of time elapses, according to the technical gist of the present invention, the compressor and the indoor fan are first turned off at the same time and the EEV and the outdoor fan are simultaneously turned off after a set amount of time has passed. That is, to more easily accomplish the stop operation control of an air conditioner during the heating operation, the present invention suggests that a pressure difference between the inlet side and the outlet side of the compressor, or a temperature difference between a condenser and an evaporator should be detected after the simultaneous turn-offs of the EEV and the outdoor fan, and a turn-off time of the four-way valve should be decided based on the detection result (i.e., the pressure difference or the temperature difference). As a result, the present invention can prevent an impact noise at the four-way valve due to a pressure difference that occurs when the four-way valve automatically returns to a position for cooling operation after the heating operation of an air conditioner stops.

While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

1. A method for controlling a stop operation of an air conditioner having a compressor, a four-way valve, an electronic expansion valve (EEV), an indoor fan and an outdoor fan, the method comprising the steps of:

turning off the compressor and the indoor fan if an operation stop signal is issued during a heating operation of the air conditioner;

checking an amount of elapsed time and turning off the EEV and the outdoor fan if an amount of elapsed time after the turn-offs of the compressor and the indoor fan reaches a preset reference time;

detecting pressures at an inlet side and at an outlet side of the compressor to calculate a pressure difference therebetween; and

turning off the four-way valve if the calculated pressure difference reaches a preset reference pressure difference.

2. The method of claim 1, wherein the preset reference pressure difference is about 3 mb.

3. A method for controlling a stop operation of an air conditioner including a condenser and an evaporator in a structure that a compressor, a four-way valve, an EEV, an indoor fan and an outdoor fan are physically connected to one another, the method comprising the steps of:

turning off of the compressor and the indoor fan if an operation stop signal is issued during a heating operation of the air conditioner;

turning off the EEV and the outdoor fan, if the amount of elapsed time after the turn-offs of the compressor and the indoor fan reaches a preset reference time;

detecting temperatures at the condenser and at the evaporator to calculate a temperature difference therebetween; and

turning off the four-way valve if the calculated temperature difference reaches a preset reference temperature difference.

4. The method of claim 4, wherein the preset reference temperature difference is about 10° C.

5. An air conditioner capable of preventing an impact noise generated after the completion of a heating operation of the air conditioner, which comprises:

a compressor;

a four-way valve;

an electronic expansion valve;

an indoor fan;

an outdoor fan;

a first and a second pressure sensors for detecting pressures at an inlet side and at an outlet side of the compressor, respectively; and

a controller for turning off the compressor and the indoor fan, turning off the electronic expansion valve and the outdoor fan in a preset reference time after the turn-offs of the compressor and the indoor fan, and turning off the four-way valve if the pressure difference between the inlet side and the outlet side of the compressor reaches a preset reference pressure difference.

6. The air conditioner of claim 7, wherein the preset reference pressure is about 3 mb.

7. An air conditioner capable of preventing an impact noise generated after the completion of a heating operation of the air conditioner, which comprises:

a compressor;

a four-way valve;

an electronic expansion valve;

an indoor fan;

an outdoor fan;

a condenser;

an evaporator;

a first and a second temperature sensors for detecting temperatures at the condenser and at the evaporator, respectively; and

a controller for turning off the compressor and the indoor fan, turning off the EEV and the outdoor fan in a preset reference time after the turn-offs of the compressor and the indoor fan, and turning off the four-way valve if the temperature difference between the condenser and the evaporator reaches a preset reference temperature difference.

8. The air conditioner of claim 10, wherein the preset reference temperature difference is about 10° C.