JPH07248140A - Defrosting controller for air conditioner - Google Patents

Abstract

PURPOSE:To ensure proper defrosting control even under any environment by detecting it. CONSTITUTION:An air conditioner comprises a compressor, a four-way valve, an outdoor heat exchanger, pressure reducing means, and an indoor heat exchanger, all being coupled in this order. In the air conditioner, there are provided an outdoor heat exchanger temperature detector 6, defrosting initiation temperature set means 7, mask time set means 8 for setting time (mask time) from the initiation of heating operation to the initiation of defrosting, a timer 9, defrosting initiation decision means 10, temperature gradient estimation means 11, return condition set means 12 for setting conditions that the operation returns from defrosting operation is heating operation based upon the temperature gradient, and control means 13. As the heating operation is initiated and temperature of the outdoor heat exchanger reaches defrosting initiation temperature with the lapse of the mask time, the defrostion is intiated, and conditions for the operation to return to the heating operation are determined on the basis of the magnitude of the temperature gradient of the outdoor heat exchanger and the conditions are reached, the operation returns to the heating operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner controller, and more particularly to defrost control.

[0002]

2. Description of the Related Art Conventionally, a defrost control device for an air conditioner in which a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a pressure reducing means 4 and an indoor heat exchanger 5 are sequentially connected is shown in FIG. As described above, the outdoor heat exchanger temperature detector 6 for detecting the temperature of the outdoor heat exchanger, the defrosting start temperature setting means 7 for setting the defrosting start temperature of the outdoor heat exchanger, and the heating operation start Mask time setting means 8 for setting a time (mask time) for suppressing the start of frost, and a timer 9 for measuring heating operation time and the like.
And a return temperature setting means 12 for setting the temperature condition of the outdoor heat exchanger for returning to the heating operation, and as shown in the operation flowchart of FIG. 7, after the mask time has elapsed from the start of the heating operation, the outdoor heat exchange is performed. The temperature of the heat exchanger was monitored, and defrosting was started when the temperature of the outdoor heat exchanger reached the defrosting start temperature, and the heating operation was resumed when the temperature reached the restoration temperature. However, the mask time is set to be long so as not to be frequently switched to the defrosting operation during the heating operation so as not to be defrosted even when the set defrosting start temperature is reached. Therefore, in an environment where the outside air temperature is low and the humidity is high, the temperature of the outdoor heat exchanger becomes too low after the mask time has elapsed, and even when the normal set recovery temperature is reached, defrosting cannot be completed completely and some ice is not formed. Since it remains, there is a problem that the heating capacity is significantly reduced by repeating this.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and detects even in an environment where the outside air temperature is low and humidity is high to completely defrost and leave no frost residue. An object is to provide a defrosting control device for an air conditioner that performs efficient defrosting control.

[0004]

According to the present invention, in order to solve the above-mentioned problems, the refrigerant discharged from the compressor 1 is supplied to the four-way valve 2.
In the air conditioner that supplies the indoor heat exchanger 5 by the decompression means 4 via the outdoor heat exchanger 3 and the like, the outdoor heat exchanger temperature detector 6 for detecting the temperature of the outdoor heat exchanger, and the outdoor heat exchanger. Defrost start temperature setting means 7 for setting the defrost start temperature of the exchanger, mask time setting means 8 for setting the time (mask time) during which the defrost start is suppressed from the heating operation start, the heating operation time, etc. , A defrosting start judging means 10 for judging defrosting start, a temperature gradient calculating means 11 for calculating a gradient of the temperature detected by the outdoor heat exchanger temperature detector 6, and a temperature gradient for calculating the temperature gradient. Reset condition setting means 12 for setting a condition for returning from the defrosting operation to the heating operation based on
And a control unit 13 that controls each means, starts the heating operation, the temperature of the outdoor heat exchanger reaches the defrosting start temperature, and the defrosting is started when the mask time elapses. The condition for returning to the heating operation is determined according to the magnitude of the temperature gradient, and the heating operation is controlled so as to reach the condition.

[0005]

With the above configuration, after the heating operation is started and the mask time has elapsed, defrosting is started until the temperature of the outdoor heat exchanger reaches the defrosting start temperature, and the outdoor heat exchanger until defrosting starts. It is possible to know the frosted state by calculating the temperature gradient of, and when the temperature gradient is large, that is, when there is a lot of frost, the defrost time is set long, and when the temperature gradient is small, that is, when there is little frost, Appropriate defrosting control is performed by setting the defrosting time short.

[0006]

Embodiments of the defrosting control apparatus for an air conditioner according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of essential parts showing an embodiment of a defrost control device for an air conditioner according to the present invention, and FIG. 2 shows the refrigeration cycle thereof. In the figure, 1 is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is a pressure reducing means, 5 is an indoor heat exchanger, and the outdoor heat exchanger 3 is provided with a temperature detector 6. Defrosting start temperature setting means 7 sets the defrosting start temperature of the outdoor heat exchanger 3. A mask time setting means 8 sets a time (mask time) during which the defrosting start is suppressed from the heating operation start so that the defrosting operation is not frequently switched to during the heating operation. A timer 9 measures the heating operation time and the like. Reference numeral 10 is a defrosting start judging means for judging the start of defrosting. The defrosting start temperature, the temperature of the temperature detector 6 provided in the outdoor heat exchanger 3 based on the mask time, and the timer 9
The elapsed time from the start of heating operation is monitored to determine the start of defrosting. Reference numeral 11 is a temperature gradient calculating means for calculating the temperature gradient of the outdoor heat exchanger. Reference numeral 12 denotes a return condition setting means, which sets a condition for returning to the heating operation during defrosting based on the temperature gradient of the outdoor heat exchanger 3 before the defrosting start calculated by the temperature gradient calculating means. Reference numeral 13 is a control unit, which controls the above-mentioned means in a timely manner. 14 is a four-way valve driving means, which drives the four-way valve 2 under the control of the control unit 13. Reference numeral 15 is a compressor driving means, which drives the compressor under the control of the control unit 13.

Next, the operation principle of the above configuration will be described. FIG. 3 shows the temperature change of the outdoor heat exchanger during operation. In the figure, curve (1) shows the temperature change when the outside air temperature is low but humidity is low, and curve (2) shows the temperature change when the outside air temperature is low and the humidity is high.
T1 is a set defrosting start temperature, T21 and T22 are return temperatures in the curves (1) and (2), and T3.
1 and T32 indicate the temperatures at the start of defrosting on the curves (1) and (2), t1 and t2 indicate the times when the defrosting start temperature T1 on the curves (1) and (2) is reached, and t2 -11 and t2-12 indicate the time from when the defrosting start temperature T1 in the curve (1) and the curve (2) is reached until the mask time tm is reached and defrosting is started. Therefore, if the temperature gradients ΔT of the outdoor heat exchanger 3 before the start of defrosting in the curves (1) and (2) are ΔT11 and ΔT12, the temperature gradients can be obtained from the following equations, and ΔTC is a constant. If so, ΔT11
<ΔTC <ΔT12. ΔT11 = (T1-T31) / (t2-t11) <ΔT
C ΔT12 = (T1-T32) / (t2-t12)> ΔT
C Therefore, the temperature gradient of the outdoor heat exchanger 3 before the start of defrosting is ΔT
Then, if ΔT <ΔTC, the return temperature T2 is set to a small T21, and if ΔT> ΔTC, the return temperature T2 is set to a large T22. Is low but the humidity is low, the defrosting time can be shortened (t31-2), and the defrosting time is long (t32) when the outside air temperature is low and the humidity is high as shown in the curve (2).
It is possible to perform defrost control so that there is no frost residue in step (2).

Next, the defrosting operation based on the above configuration and operating principle will be described with reference to the flowchart of FIG. When the heating operation is started in step 0 (ST0), the timer 9 is set and the time measurement is started in ST1. S
At T2, it is monitored whether the temperature T of the outdoor heat exchanger 3 is lower than the defrosting start temperature T1. At ST3, the time t = t1 when T <T1 is recorded. In the example of FIG. 3, t = t11 in the case of the curve (1) and t = t12 in the case of the curve (2). In ST4, it is monitored whether the mask time tm has been reached since the start of the heating operation. In ST5, t>
The time t = t2 when tm is reached and the temperature T = T3 of the outdoor heat exchanger 3 at that time are recorded, and the timer is reset. In the example of FIG. 3, in the case of the curve (1), T = T31,
In the case of the curve (2), T = T32. In ST6, the temperature gradient is calculated, and in ST7, the calculation result is the predetermined value Δ.
When it is smaller than Tc, that is, when ΔT <ΔTc, the heating return temperature is set to a lower predetermined value ΔT21, and ΔT> Δ
In the case of Tc, the heating return temperature is set to a higher predetermined value ΔT22 and the defrosting operation is started. In ST8, it is monitored whether the temperature T of the outdoor heat exchanger 3 reaches the heating return temperature T21 or T22. In ST9, T> T21 or T
When> T22, the defrosting operation is ended, the heating operation is restored, and the process returns to ST1.

[0009]

As described above, according to the defrosting control device for an air conditioner of the present invention, the temperature of the outdoor heat exchanger 3 before the start of defrosting is detected, the temperature gradient ΔT is calculated, and a constant is calculated. Δ
Compared with TC, when the temperature is smaller than a constant, the return temperature T2 is set low, and when the value is larger than the constant, the return temperature T2 is set to a large value.
When there is little frost, defrost time is shortened to eliminate waste of defrost time, and when there is a lot of frost, such as when the outside air temperature is low and humidity is high, the defrost time is set long so that no frost remains. The defrosting can be performed, and efficient defrosting control can be performed.

[Brief description of drawings]

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

FIG. 2 is a refrigeration cycle diagram showing an embodiment of a defrost control device for an air conditioner according to the present invention.

FIG. 3 is a diagram illustrating a change in temperature of the outdoor heat exchanger during operation for explaining the operation principle of the defrosting control device for an air conditioner according to the present invention.

FIG. 4 is a flowchart for explaining the operation of the defrosting control device for an air conditioner according to the present invention.

FIG. 5 is a principal block diagram showing a conventional defrost control device for an air conditioner.

FIG. 6 is a diagram showing a temperature change of the outdoor heat exchanger during operation of the conventional defrosting control device for an air conditioner.

FIG. 7 is a flowchart of a conventional defrost control device for an air conditioner.

[Explanation of symbols]

 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Pressure reducing means 5 Indoor heat exchanger 6 Temperature detector 7 Defrosting start temperature setting means 8 Mask time setting means 9 Timer 10 Defrosting start judging means 11 Temperature gradient calculating means 12 Recovery Condition setting unit 13 Control unit 14 Four-way valve drive unit 15 Compressor drive unit T1 Defrost start setting temperature T2 Return temperature T3 Defrost start temperature

Claims (4)

[Claims] 1. An air conditioner that supplies refrigerant discharged from a compressor to an indoor heat exchanger by a pressure reducing means via a four-way valve, an outdoor heat exchanger, etc., and detects the temperature of the outdoor heat exchanger. A heat exchanger temperature detector, a defrosting start temperature setting means for setting a defrosting start temperature of the outdoor heat exchanger, and a mask for setting a time (mask time) during which the defrosting start is suppressed from the heating operation start. Time setting means, a timer for measuring the heating operation time, etc., a defrosting start judging means for judging defrosting start, a temperature gradient calculating means for calculating a gradient of the detected temperature of the outdoor heat exchanger temperature detector, A return condition setting means for setting a condition for returning from the defrosting operation to the heating operation based on the temperature gradient is provided, and a control unit for controlling each means is provided, and after the heating operation is started, the temperature of the outdoor heat exchanger is Defrost start temperature is reached and mask time It is characterized in that defrosting is started as time passes, and a condition for returning to the heating operation is determined according to the temperature gradient of the outdoor heat exchanger until the defrosting is started, and the heating operation is returned when the condition is reached. Defrost control device for air conditioner. 2. The defrost control device for an air conditioner according to claim 1, wherein the return condition setting means sets a defrost time as a condition. 3. The return condition setting means sets the temperature of the outdoor heat exchanger as a condition.
A defrosting control device for the air conditioner described. 4. The defrosting control device for an air conditioner according to claim 1, wherein the return condition setting means sets the defrosting time and the temperature of the outdoor heat exchanger as conditions.