JPH07139785A - Defrost controller for air conditioner - Google Patents

Abstract

PURPOSE:To determine a starting temperature and a releasing temperature of the next defrosting in response to the time required for previous defrosting in the case of defrosting an outdoor unit at the time of heating of an air condi tioner. CONSTITUTION:In the case of defrost controlling of an outdoor unit at the time of heating of an air conditioner, the temperature sensor 1e for detecting the temperature of an outdoor heat exchanger 1d to become a defrost starting temperature or a defrost releasing temperature, a timer 1b for measuring a time required for defrosting at an outdoor unit 1, a memory h1 for updating a measured time at each measuring to store it, a comparator 1j for comparing a predetermined time for previous defrosting with a predetermined reference time, and a controller 1a for controlling as prescribed are provided in the unit 1. The starting temperature and the releasing temperature in next defrosting from the previous time are set to different temperatures in response to a length of the stored previous required defrosting time from the reference time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting control method for an air conditioner, and more particularly, in defrosting an outdoor unit during heating operation, the next time depending on the time required for the previous defrosting. Defrosting control for changing the defrosting start temperature and the defrosting temperature.

[0002]

2. Description of the Related Art Conventionally, defrosting during heating operation has been performed as shown in the flowchart of FIG. The ST number in the following description indicates each step in FIG. When the outdoor unit 1 shown in FIG. 1 is heated, the control unit 1a of the outdoor unit 1 defrosts at regular time intervals (M minutes to, for example, 40 minutes), so the timer 1b is set as a timer to start time counting. Allow (ST31). Also, the compressor (CM) 1c is turned on (ST32).
After the lapse of the M minutes (ST33-Y), the temperature of the outdoor heat exchanger 1d detected by the temperature sensor 1e is the predetermined temperature T1 (for example, -6).
(ST34-Y), the control unit 1a turns off (stops) the four-way valve 1f, the outdoor unit fan 1g, and the fan 2b of the indoor unit 2 (ST35) and defrosts. Indoor unit 2
The fan 2b is turned off by cooperation between the control unit 1a of the outdoor unit 1 and the control unit 2a of the indoor unit 2. After the start of the defrosting, when the temperature of the outdoor heat exchanger 1d rises above a predetermined temperature T2 (for example, + 10 ° C) (ST36-Y), the defrosting is terminated, and the control unit 1a controls the four-way valve 1f and the outdoor unit fan. 1g and the fan 2b of the indoor unit 2 are turned on (operated) (ST37) to return to heating operation. Then, the timer for M minutes is set again (ST3
8). Hereinafter, this operation is repeated.

[0003]

In the conventional defrosting operation described above, the outdoor heat exchanger is not frosted because the relative humidity is low even if the outside air temperature is low enough to enter defrosting ( Or, there may be a state of (small). In this case, useless defrosting is performed. The present invention, in order to prevent the useless defrosting as described above, when performing defrosting, the defrosting starting temperature and the defrosting releasing temperature are changed from the time required for the previous defrosting. An object is to provide a frost control device.

[0004]

According to the present invention, a temperature sensor for detecting the temperature of an outdoor unit heat exchanger, measuring means for measuring the time required for defrosting, and updating the measured time for each measurement. Storage means for storing, comparison means for comparing the required time in the previous defrost and a predetermined reference time, the defrost start temperature and the defrost release temperature in the next defrost with respect to the previous The defrosting control device for an air conditioner is provided with means for changing the setting to different temperatures according to the length of the previous defrosting required time with respect to the reference time.

[0005]

The first (first) defrost is performed at the preset defrost start temperature and defrost release temperature. The time required for this defrosting is stored. Defrosting performed next (next time) determines the defrosting start temperature and defrosting release temperature depending on whether the time required for the previous defrosting was longer or shorter than the preset reference time. change. These temperatures are set in advance according to the length of the reference time,
Set to any temperature from the previous required time.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A defrost control device for an air conditioner according to the present invention will be described below with reference to the drawings. 1 is a refrigerant circuit diagram and a control block diagram showing an embodiment of a defrosting control device for an air conditioner according to the present invention, and FIG. 2 is a flow chart for explaining the operation. In FIG. 1, 1 is an outdoor unit provided with a control unit 1a, a timer 1b, a memory unit 1h and the like, and 2 is an indoor unit provided with a control unit 2a, a fan 2b and the like. Figure 1 shows the state of heating operation (four-way valve 1f), the refrigerant is the compressor (CM) 1c,
The refrigerant from the indoor heat exchanger 2 flows through the four-way valve 1f, and the refrigerant from the indoor heat exchanger 2 passes through the capillary tube 1k as the refrigerant throttle means, the outdoor heat exchanger 1d, and the four-way valve 1f, and then the compressor.
Return to 1c. In the cooling operation, the four-way valve 1f is switched as shown by the dotted line. The compressor 1c that circulates the refrigerant, and the fan 1g that turns on and off in conjunction with the compressor and sends air to the outdoor heat exchanger 1d, operate under the control of the control unit 1a. Further, a temperature sensor 1e is provided to detect the temperature of the outdoor heat exchanger 1d, and the detected temperature data is sent to the control unit 1a. Furthermore, the timer 1 described below is connected to the control unit 1a.
b, a memory unit 1b and a comparison unit 1j are provided.

When the heating operation is performed, the control unit 1a defrosts at regular intervals (M minutes to 40 minutes, for example).
To set the timer to start time counting (ST
1). Further, the compressor (CM) 1c is turned on (ST2). When the fixed time (M minutes) has elapsed, the defrosting start time comes (ST3-Y), and the control unit 1a determines whether the defrosting is less than the second time (ST4). This judgment is less than the second time (that is, 1
In the case of (the fourth time) (ST4-Y), defrost is performed by the following flow. When the temperature of the outdoor heat exchanger 1d detected by the temperature sensor 1e is lower than or equal to the predetermined temperature T1 (-6 ° C in this embodiment) (ST5-Y), the control unit 1a measures the time required for defrosting. For this purpose, a timer set (timer 1b) is set (ST6), and the four-way valve 1f, the outdoor unit fan 1g, and the indoor unit fan (not shown) are turned off (stopped) (ST7) to start defrosting.

After the start of the defrosting, when the temperature of the outdoor heat exchanger 1d rises above a predetermined temperature T2 (+ 8 ° C in this embodiment) (ST8-Y), the defrosting is released and the control section 1a The time required for defrosting is stored in the memory unit 1h (ST9). This memory updates the previous data each time it is stored. After the same memory, the control unit 1a has a four-way valve 1f and an outdoor unit fan 1
g and the indoor unit fan are turned on (operated) respectively (ST1
0) Return to heating operation. Then, the timer for M is set again (ST11). On the other hand, when the defrosting is not less than the second time (second time or more) (ST4-N), the defrosting is performed by the following flow. The control unit 1a reads the time to required for the previous defrosting from the memory unit 1h, and the same time to and a predetermined reference time ts (4 minutes in this embodiment) are compared by the comparison unit 1j. Let them compare. When this comparison result is to ≧ ts, the above-mentioned ST
Defrost according to the flow after 5 (ST12-N). The reason for doing this is that it was judged that there was a lot of frost because it took a long time so that the previous defrosting became to ≧ ts, and this frost is expected to be in the same state as the previous time. This is because defrosting is sufficiently performed.

When the time to required for defrosting last time is equal to or less than the reference time ts (ST12-Y), contrary to the above, it is judged that the amount of frost last time was small, and the frosting this time was also last time. The defrosting start temperature is predicted to be in the same state as
The temperature is changed to T3 (-8 ° C in this embodiment) lower than -6 ° C. By this change, it is possible to start defrosting from a frosted state. When the temperature of the outdoor heat exchanger 1d becomes equal to or lower than the predetermined temperature T3 (ST13-Y),
The control unit 1a performs a timer set (timer 1b) for measuring the time required for the current defrosting (ST14), and the four-way valve 1
f, the outdoor unit fan 1g, and the fan 2b of the indoor unit 2 are turned off (stopped) (ST15) to start defrosting. After the start of the defrosting, when the temperature of the outdoor heat exchanger 1d rises to a predetermined temperature T4 (+ 10 ° C in the present embodiment) or more (ST16-Y), the defrosting is released, and the control unit 1a requires the defrosting. The time that has been done is stored in the memory unit 1h (ST9). The time memorized here becomes the judgment time for determining the next defrosting. Where T4
The reason why (+ 10 ° C) is set higher than T2 (+ 8 ° C) is that there is a possibility that the amount of frost is increased because the defrosting start temperature is lowered as described above. ST9
After that, the above-described flow is performed, and thereafter, the above operation is repeated.

[0010]

As described above, according to the present invention, when defrosting the outdoor unit during the heating operation, the time required for the previous defrosting is compared with a preset reference time, Since the defrost start temperature and defrost release temperature are changed according to
Unlike the conventional case where defrosting is started and ended based on a uniformly set temperature, useless defrosting called empty defrosting can be reduced. Further, by reducing the defrosting in the air, the disturbance in the room temperature is reduced, the comfort during the heating operation can be improved, and the function as the air conditioner is improved.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram and a control block diagram showing an embodiment of a defrost control device for an air conditioner according to the present invention.

FIG. 2 is an operational flowchart for explaining the present invention.

FIG. 3 is an operation flowchart for explaining conventional defrosting.

[Explanation of symbols]

 1 outdoor unit 1a outdoor unit control unit 1b timer 1c compressor 1d outdoor heat exchanger 1e temperature sensor 1f four-way valve 1g fan 1h memory unit 1j comparison unit 2 indoor heat exchanger

Claims (3)

[Claims] 1. A temperature sensor for detecting an outdoor unit heat exchanger temperature, a measuring unit for measuring a time required for defrosting, a storage unit for updating and storing the measured time for each measurement.
Comparing means for comparing the required time in the previous defrost and a predetermined reference time, and the previous defrost required storing the defrost start temperature and the defrost release temperature in the next defrost for the previous time. A defrosting control device for an air conditioner, comprising: means for setting and changing the temperature to different temperatures according to the length of time relative to a reference time. 2. The defrosting starting temperature when the required time in the previous defrosting is shorter than the reference time is set to be lower than the predetermined temperature when the required time is longer than the reference time. Item 1. A defrost control device for an air conditioner according to Item 1. 3. The defrost release temperature when the required time in the previous defrost is shorter than the reference time, is set higher than the predetermined temperature when the required time is longer than the reference time. Item 1. A defrost control device for an air conditioner according to Item 1.