JPS60122848A - Operation control device for air conditioner - Google Patents

Abstract

PURPOSE:To allow a stabilized control of the defrosting operation of an air conditioner by making the appropriate correction to a judgment criterion as a command signal to start the defrosting operation so that even if the room temperature signal detected by a room temperature sensor is temporarily disturbed, an accurate defrosting operation command signal may be obtained without being influenced by the disturbance. CONSTITUTION:The defrosting operation is performed only when the temperature reduction DELTAT from the initial maximum value To of the differential temperature T between the condensing temperature Tc of the refrigerant in a room side heat exchanger 12 and the room temperature TA is maintained above a predetermined differential temperature for a duration of time t2. Because of this, even if the warm air blown by a room fan 13 hits a room temperature sensor 17 by an external disturbance to cause the room temperature sensor to temporarily output a temperature signal higher than the actual room temperature TA, the mere fact only of such will not start the defrosting operation. Therefore, the defrosting operation of an air conditioner can be controlled in a stabilized manner.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an operation control device for an air conditioner, in particular,
This invention relates to a defrost operation that removes frost formed on an outdoor heat exchanger under predetermined conditions during heating operation.

(Prior Art) Conventionally, as an operation control device for an air conditioner having this type of defrost operation function, for example, Japanese Patent Application Laid-Open No. 55-1504
As disclosed in Publication No. 47, etc., the temperature difference between the condensation temperature of the refrigerant in the indoor heat exchanger during heating operation and the room temperature detected by the room temperature sensor is eliminated, and this temperature difference is detected at the beginning of the heating operation. If the temperature decreases by more than a predetermined value (for example, 4°C) from the maximum value, it is determined that frost has formed on the outdoor heat exchanger, which will lead to a decrease in heating capacity, and the refrigerant circulation path is closed. It is known that the defrost operation is performed by switching to the opposite cycle (cooling cycle) from the heating cycle.

However, in this conventional system, the room temperature detected by the room temperature sensor is input as a control signal, so if the warm air blown out by the indoor fan hits the room temperature sensor due to some external disturbance, the room temperature sensor may detect the actual room temperature. If a room temperature signal higher than that is output, the temperature difference between the condensation temperature of the refrigerant and the room temperature will be determined to be small accordingly, and as a result, defrost operation will not be performed even in operating conditions that do not normally require defrost operation. There was a risk that this could result in malfunction.

(Objective of the Invention) The object of the present invention is to make appropriate corrections to the above-mentioned criteria for starting the defrost operation, so that even if the room temperature signal detected by the room temperature sensor is temporarily disturbed, the The purpose of the present invention is to provide an accurate defrost operation command signal 1q without causing any problems, thereby stabilizing the control of the defrost operation of an air conditioner.

(Structure of the Invention) In order to achieve the above object, the solution means of the present invention is as shown in FIG.
7), and a condensing temperature detection means (18) for detecting the condensation temperature (Tc) of the refrigerant in the indoor heat exchanger during heating operation;
The condensation temperature detection means (18) and the room temperature detection means (17)
), condensing temperature (Tc) and room temperature (TA)
and determining means (21) for determining that the temperature difference between The control means (22) outputs a defrost operation command signal when the condition continues for a predetermined period of time. As a result, the criteria for determining whether the air conditioner should perform defrost operation has been expanded and stabilized.

(Effects of the Invention) Therefore, according to the present invention, during the heating operation of the air conditioner, the temperature difference between the condensation temperature of the indoor heat exchanger and the room temperature decreases by a predetermined value or more from its initial maximum value for a predetermined period of time. The defrost operation command signal is output only when the defrost operation continues, so even if a temporarily high room temperature signal is output due to hot air hitting the room temperature sensor, an accurate defrost operation command signal can be obtained without being affected by it. Therefore, it is possible to prevent malfunctions in the defrost operation of the air conditioner and to stabilize its control.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIG. 2 and the subsequent drawings.

FIG. 2 shows a refrigerant circuit of an air conditioner according to an embodiment of the present invention, (1) shows outdoor units 1 to 1, and (2) shows a liquid side refrigerant pipe (3) and a gas side connected to the outdoor unit (1). Refrigerant piping (
The outdoor unit 1-(1) is an indoor unit connected via a compressor (5), an outdoor heat exchanger (
6), four-way switching valve <7>, gas-liquid separator (8), key pillar tube (9), (9),..., check valve (1Q
), an outdoor fan (11), etc., while the indoor unit (2) includes an indoor heat exchanger (12) and an indoor fan (13). The above-mentioned refrigerant distribution devices are connected by refrigerant piping (14) as shown in the figure, and the four-way switching valve (7) is switched to allow the refrigerant to flow as shown by the solid line arrow in the figure during cooling. Outdoor heat exchanger (6
) and then evaporated in the indoor heat exchanger (12) to perform cooling operation. During heating, the refrigerant is flowed as shown by the dashed arrow in the figure and condensed in the indoor heat exchanger (12). The refrigerant is then evaporated in the outdoor heat exchanger (6) to perform heating operation, and when performing defrost operation to remove frost formed on the outdoor heat exchanger (6) during heating. In the same way as during the cooling operation described above, the air is allowed to flow and condensed heat is generated in the outdoor heat exchanger (6), and the outdoor and indoor fans (11) and (13) are stopped.

In addition, in the outdoor unit (1), a gas-liquid separator (
8) and the injection boat (5a) of the compressor (5)
are connected by a gas injection bypass pipe (16) with a control solenoid valve (15) interposed therein, and when performing heating-up operation with increased heating capacity during heating, the control solenoid valve (15) is connected to the gas injection bypass pipe (16). By opening it and injecting intermediate pressure gas into the compressor (5), capacity-up operation was performed and heating capacity was suppressed during heating [! ! When performing the air conditioner save operation or the above-mentioned defrost operation, or when performing the air conditioner operation, the control solenoid valve (15) is closed to stop the injection of intermediate pressure gas into the compressor 111 (5), thereby reducing the capacity. I try to do it.

Figure 3 shows the compressor (5) and four-way switching valve (7).

A control system for controlling the operation of a control solenoid valve (15), an outdoor fan (11), and an indoor fan (13) is shown, and (17) is a room temperature sensor consisting of a thermistor as a room temperature detection means for detecting room temperature (TA). The sensor (18) is a condensation temperature sensor consisting of a thermistor as a condensation temperature detection means for detecting the condensation temperature (Tc) of the refrigerant in the indoor heat exchanger (12) during heating operation, and Sensor (17).

The output of (18) is sent to the compressor (5), four-way switching valve (7), control solenoid valve (1'5), and outdoor fan (11) in response to the output signals of each sensor (17) and (18). and is input to the controller 1 to the roll unit (19) that control the indoor fan (13). The control unit (19) is equipped with a microcomputer (20), and as one of its signal processing functions, the microcomputer (20〉) detects the condensing temperature (Tc) detected by the condensing temperature sensor (18) and the room temperature sensor (18). The temperature difference (T > ((T) = (Tc) - (TA)) from the room temperature (TA) detected in step 17) is calculated, and the temperature difference (T) is determined to be the maximum temperature difference (To
) is determined to be in a temperature difference change state where the temperature difference has decreased by more than a predetermined temperature (ΔTo> (for example, 4°C) It has a function to make it perform.

The microcomputer (20) of this control unit (19) controls the condensation temperature sensor (18).
) and room temperature sensor (17), the condensing temperature (
Discrimination means for discriminating that the temperature difference (T) between Tc ) and room temperature (TA) has decreased by a predetermined value (ΔTo) or more from its initial maximum value (To ) and outputting a temperature difference change signal <21
) and the determination means (21), and when the temperature difference change state continues for a predetermined time (t2), a defrost operation command signal is sent to the four-way selector valve (7), the outdoor fan (11), and the indoor fan. Control means (22) outputting to (13)
is composed of.

Next, regarding the operation of the above control system during heating operation,
Explaining with reference to the flowchart shown in FIG. 4, after starting, first, in step (SI), the compressor (5) is
Then, operate the outdoor fan (11) and switch the four-way selector valve (7) to the heating cycle, then step (
In step S2), the condensation temperature (Tc >
After detecting and storing, it is determined in step (S3) whether or not the condensation temperature (Tc) is 35°C or higher,
When this determination is No, the process returns to step (S2), and when the determination is YES, the indoor fan (13) is operated in step (S4). The above steps (S2) ~ <S
4) prevents cold air from being blown into the room when heat exchange in the indoor heat exchanger (12) is insufficient at the start of heating operation.

Thereafter, in step (S5), it is determined whether a predetermined time (1+) (for example, 15 minutes) has elapsed since the start of the heating operation, and if this determination is No, the same step (S5) is continued. This step (S5) ensures that the heating operation shifts to a stable state. When the determination in step (S5) is YES, the condensation temperature (Tc) of the refrigerant in the indoor heat exchanger (12) and the room temperature (TA) are detected in step (S6), and step (S7) is performed. Then, the temperature difference (T>) between this refrigerant condensation temperature (Tc) and the room temperature (TA>) is calculated to find the maximum value (To) after the start of heating operation, that is, there is still frost on the outdoor heat exchanger (6). The value is held as the value in the state where heat exchange is performed with high efficiency without generation.

Next, in step <S8), the degree of condensation fffi (Tc
) and room m (TA), and in step (S9), the temperature difference (T) between both temperatures (Tc) and (TA) ((T) = (
After calculating the amount of decrease (6 guns) ((ΔT) = (To) - (T)) of Tc > (TA)) from the above initial maximum value (To), the amount of decrease (ΔT) is calculated in step (Sho). It is determined whether or not exceeds a predetermined value (ΔTo>(=4°C)). If this determination is NO, it is assumed that defrost operation is unnecessary, and the memory signal (
After setting N) to "OII", the process returns to the above step (S8).

When the determination is YES, in step (812), the condensation temperature (
After prohibiting both thermostat stop and heating capacity switching control so as not to change Tc >, step (SI
3>, replace the memory signal (N) with “N +1”,
Next, in step (814), it is determined whether the memory signal (N) is greater than or equal to a predetermined number (t,) (=60), and if this determination is NO, the step (S8) is performed.
) and repeat the control flow. By setting the repetition cycle time of this control flow to a certain period of time (for example, 1 second), the determination in step (814) can be made that the temperature difference between the condensed humidity (Tc) and the room temperature (1-A) is
Amount of decrease (△T) from the initial maximum value (To) of T )
It is determined whether or not the state in which the temperature exceeds a predetermined temperature (ΔTo) continues for a predetermined time (60 seconds).

Then, when the determination becomes YES by repeating the above control flow, it is determined in step (Szs) whether or not the cumulative operating time of the compressor (5) has elapsed (ts) time (for example, 32 minutes); If this determination is No, the process returns to step <S8>. This is done to ensure a constant heating operation time.

On the other hand, if the determination in the above step (Szs) is YES, the outdoor and indoor fans (
11), (13) and four-way switching valve (7).
After switching to the cooling cycle and starting the defrost operation, in step (Say), the refrigerant condensation temperature (Tc) in the indoor heat exchanger (12) and the set air volume of the indoor fan (13) are set. Defrosting time (t4) (for example, 4 to 10 minutes) is set, and while determining whether or not this defrosting time (t4) has elapsed in step (S's), the defrosting time (t4) is set.
), the defrost 1 operation is performed until the time period elapses.

When the defrosting time (t4) has elapsed and the determination in step (S's) becomes YES, the compression m(
At the same time as stopping the operation of the outdoor fan (11), the operation of the outdoor fan (11) is started, and this state is maintained for a predetermined time (
ts) (for example, 1 minute), then step (8)
2+) to operate the compressor (5). Compressed II like this
By starting the I (5) later than the outdoor fan (11), the refrigerant on both sides of the four-way selector valve (7) when switching the four-way selector valve (7) in step (823) described later. The pressure is balanced and abnormal noise is prevented. After this, in step (822), the predetermined time (js) (for example, 2 seconds) vl is regulated from the start of operation of the compressor (5), and in the last step <823), the four-way switching valve (7) is heated. Switch to cycle. The reason for performing delayed switching of the four-way switching valve (7) is to prevent switching failure from occurring. After the above step (S23), the process returns to step (S2), and one cycle of all control flows is thus completed, and the same cycle as above is repeated thereafter.

Therefore, in this case, when performing defrost operation during heating operation of the air conditioner, the initial temperature difference (T) between the refrigerant condensation temperature (Tc) and room temperature (TA) in the indoor heat exchanger (12) is When the temperature difference change state in which the decreasing change temperature (ΔT) from the maximum value (To) continues for a predetermined time (t2), defrost operation is performed for the first time, and the air is blown from the indoor fan (13). Even if the heated air hits the room temperature sensor (17) due to a disturbance and the room temperature sensor (17) temporarily outputs a temperature signal indicating a temperature higher than the actual room temperature (TA), the defrost operation starts immediately. will not be done,
Therefore, the defrost operation of the air conditioner can be stably controlled.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of the present invention, Figs. 2 to 4 show embodiments of the present invention, Fig. 2 is a refrigerant circuit diagram, Fig. 3 is a block diagram of the control system, and Fig. 4 is the same. It is a flowchart figure.

Claims (1)

[Claims] (1) In an air conditioner configured to remove 1C frost formed on the outdoor heat exchanger (6) by defrosting operation,
Room temperature detection means (17) for detecting the room titil (1-8)
), and a condensation temperature detection means (18) for detecting the refrigerant condensation temperature (Tc) in the indoor heat exchanger (12) during heating operation.
and the condensation temperature detection means (18) and room temperature detection means
17), condensed variola (Tc) and room temperature (TA
) for determining that the temperature difference (T) has decreased by a predetermined 1 m (ΔTo) or more from the initial maximum value (TO) and outputting a temperature difference change state; ), the temperature difference change state continues for a predetermined time (t
2) An operation control device for an air conditioner characterized by comprising: 26) a control means for outputting a defrost operation command signal when the defrost operation continues.