JPS6142174B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a defrosting control device for a heat pump air conditioner.

Generally, when a heat pump type air conditioner is used for heating operation in winter, the heat exchange efficiency decreases due to frost formation on the outdoor coil when the outside air temperature drops, resulting in a fatal loss of power and heating efficiency. It has defects.

For this reason, the refrigerant cycle is temporarily reversed to defrost the outdoor coil, and then the refrigerant cycle is switched back to normal and the heating operation is repeated. A differential temperature defrosting device that detects the presence or absence of frost based on the temperature difference between the two types of defrosting devices has been used, and a mechanical timer defrosting device that detects the outdoor coil temperature at regular intervals has been adopted.

However, with the former type of differential temperature defrosting device, defrosting is always performed when the outside air temperature drops and the temperature difference between the outdoor coil temperature and the outdoor coil temperature reaches the set temperature difference value. It has the disadvantage that it starts defrosting unnecessarily even when there is no frost, and the latter mechanical timer defrosting device does not defrost when the outdoor coil is in a frosty state. This has the disadvantage that the defrosting process does not start until after a certain period of time, even if the air passes through the air without frosting, and then frost begins to form and the outside temperature drops significantly.

In view of this, the present invention abolishes the outside temperature detection in the former method, which is less reliable in detecting frost formation, and the timer detection in the latter method, and instead reads the indoor coil temperature to reliably detect frost formation. The present invention provides a highly accurate defrosting control device which also detects the outdoor coil temperature at the time of this detection to reconfirm the frosting state.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an electric circuit diagram of a separate heat pump type air conditioner, in which only the defrosting and heating circuits are extracted. Reference numeral 1 denotes a microcomputer having a constant voltage DC power source 2 connected to power supply terminals V ₁ and V ₂ , hereinafter referred to as a microcomputer, and its internal mechanism is constructed as shown in FIG. First, 51 is a timer mechanism, which inputs a signal every fixed period from the timer 51, and at this time, the detected value of the indoor coil sensor is input to the terminal.
Input from R ₁ . Reference numeral 53 denotes an arithmetic mechanism, which performs an arithmetic operation to determine the gradient change of the detected value input at regular intervals. 54 is a comparison mechanism;
The setting gradient (0.8
℃/6 minutes) and this change in slope, and when this change slope exceeds the set slope, a defrost signal is output. 56 is an AND gate mechanism which performs an AND operation between the defrosting signal and the signal applied to the terminal _R2 . Reference numeral 57 denotes a defrosting control mechanism, which performs defrosting operation control to be described later when a defrosting signal is given from the AND gate mechanism. Also, this microcomputer 1 has output terminal 0 ₀
The output terminals 0 to ₀₄ are connected to the reference terminal 9 of the comparator 8 via the resistors 3 to 7, and the output terminals ₀ to ₀₄ are connected to the reference terminal 9 of the comparator 8 through the resistors 3 to 7.
32 types of 5-bit output signals from [0, 0, 0, 0] to [1, 1, 1, 1, 1] are output, and a 32-step reference voltage signal is sent, and this signal is output. The output terminal of the comparator 8 is short-circuited to ground potential or opened at each time.

At the same time, from the output terminal _R1 through the resistor 10,
With a timing time longer than one cycle of 32 steps
An output voltage of 9V is generated, and at this timing, the indoor coil sensor 12 connected to the comparison terminal 11 of the comparator 8 detects the indoor coil depending on which step of 32 steps the input terminal _K1 goes from L to H. Detects the temperature and adjusts the indoor coil temperature to the set temperature of 30 degrees Celsius
If it is YES, masking is performed for 6 minutes using the timer memory function built into microcontroller 1, and the indoor coil temperature is set to Celsius during this time.
It is determined whether the temperature has exceeded 0.8°C, and further it is determined whether this state has continued three times or not, and this is stored.

13 is a comparator controlled by a transistor 14, the output terminal of which is branch-connected to the input terminal K ₁ and connected to the output terminal R ₂ via _a resistor 15; Similar to the output terminal _R1 , an output voltage of 9V is generated, and the OFF operation of the transistor 14 is sensed based on whether the input terminal _K1 changes from L to H at this timing.

16 is a terminal between units of a separate heat pump air conditioner, 17 is a compressor drive relay connected between the first terminal and the second terminal, and 18 and 19 are outdoor fans that are energized when the transistor 20 is turned on. The relay and four-way valve coil 21 is connected between the third and fourth terminals of the inter-unit terminal 16, and is closed when the outdoor coil temperature drops to -3°C or lower, and closes when the outdoor coil temperature drops to -3°C or higher. This is the contact point of the outdoor coil sensor that opens when it rises.

R ₃ and R ₄ are the output terminals from which the L signal is output during heating operation, and are connected to the bases of transistors 24 and 25 via inverters 22 and 23, respectively, and R ₅ is the output terminal where the indoor coil temperature is 30 degrees Celsius or less during heating operation. The indoor fan motor 2 is output via the inverter 26 at the output terminal where the H signal is output when the temperature is 30℃ or higher, and the L signal is output when the temperature is 30℃ or higher.
It is connected to a speed adjustment relay 28 that switches the rotation speed of 7.

In addition, 29 and 30 are the operation switch and heating switch connected in parallel between the output terminal R ₁ and the input terminal K ₂ , 31 is an interlocking switch that opens and closes at the same time as this operation switch 29, and 32 is a constant voltage DC of 9V. Power supply terminal 33 is a 24V constant voltage power supply terminal, 34,3
5, 36, 37, 38, and 39 are reverse current blocking diodes, 40 is a diode connected between the base and emitter of the transistor 14, and 41, 42, and 43 are diodes for back electromotive force protection.

The system is configured as described above, and next, the heating and defrosting operations are explained in the main flowchart in Figure 2A and in the second diagram.
The explanation will be based on the subroutine flowchart shown in FIG.

When the operation switch 29, the interlocking switch 31, and the heating switch 30 are turned on, H signals are output from the output terminals _R3 and _R4 , which are inverted to L by the inverters 22 and 23, respectively, and the transistors 24 and 25 are turned on. In addition, since the indoor coil temperature is cold and below 30 degrees Celsius at the start of heating operation, an H signal is output from output terminal _R5 within the 40 minute mask time as shown in the subroutine flowchart in Figure 2 B. Therefore, it is reversed to L by the inverter 26 and the speed control relay 28
is energized, and the relay contact 44 is connected to the low-speed side terminal 45 to rotate the indoor fan motor 27 at a low speed to prevent cold air from being blown into the room.

At the same time, as mentioned above, when the transistor 25 is turned on, the compressor driving relay 17 is excited via the second terminal of the inter-unit terminal 16, and when the transistor 24 is turned on, the relay 17 is excited via the diode 40 and the fourth terminal of the inter-unit terminal 16. When the voltage rises, transistor 20 turns on, and outdoor fan relay 18
is energized through the second terminal of the inter-unit terminal 16, and the four-way valve coil 19 is energized through the third terminal of the same terminal 16, and the four-way valve switches to the heating cycle, and the compressor and outdoor fan are driven to perform heating. Driving begins.

Due to this heating operation, the temperature of the indoor coil rises due to the heat of condensation of the high-temperature, high-pressure refrigerant discharged from the compressor, and when the temperature of the indoor coil exceeds 30 degrees Celsius, the output terminal is activated as shown in the subroutine flowchart in Figure 2 (b). The signal from R ₅ is switched to L, and is inverted to H by the inverter 26 to demagnetize the speed control relay 28, and this relay contact 44 is switched to the high speed side terminal 46 as shown in the figure, and the indoor fan motor 27 is operated at high speed. be driven.

Furthermore, when starting heating operation, the outdoor coil temperature is -
When the temperature is above 30°C, the contact 21 of the outdoor coil sensor is open, so the transistor 14 is turned off. On the other hand, when the outside temperature is cold to -3 degrees Celsius or lower, the contact 21 is closed and the transistor 14 is turned on, and the voltage level at the comparison terminal 47 of the comparator 13 is increased by the voltage dividing resistors 48 and 49 to become the reference. The voltage exceeds terminal 50 and is disconnected from the ground potential, and a signal is input from output terminal R ₂ to input terminal K _1. However, when heating operation starts, even if the outdoor coil temperature is -3 degrees Celsius or lower, there is no frost formation. Therefore, during the 40 minute mask time (predetermined time), the mask mechanism works to prevent defrosting.

Due to continued heating operation, frost begins to form on the outdoor coil, and as it becomes covered with frost, the refrigerant evaporation effect within the outdoor coil decreases, and the temperature of the indoor coil gradually decreases. It is detected by the outdoor coil sensor 12. Determines whether the indoor coil temperature is higher than the set 30 degrees Celsius, and if it is lower, YES
Then, the indoor coil temperature becomes 0.8 degrees Celsius in 6 minutes.
It is divided into half whether or not the temperature has decreased, and if the falling temperature gradient exceeds the set gradient and YES is output, it is further determined whether this state has occurred three times in a row.
As shown in FIG. 3, if the set gradient is exceeded as shown by the dashed line, YES will be output, but if it is below the set gradient, as shown by the broken line in the same figure, NO will be output and the descending temperature gradient will be determined again. If YES is output from this determination, then it is determined whether the outdoor coil temperature is below -3 degrees Celsius. When the outdoor coil temperature is below -3 degrees Celsius, the contact 21 of the outdoor coil sensor is closed as described above, and a signal is input from the output terminal R ₂ to the input terminal K ₁ .
It is determined as YES, the signal from output terminal R ₄ switches from H to L, the signal from output terminal R ₅ switches from L to H, transistor 25 turns OFF, and compressor drive relay 17 and outdoor fan relay switch. 18 is demagnetized, the compressor and the outdoor fan stop, and the speed regulating relay 28 is energized and the contact 44 is switched, causing the indoor fan motor 27 to rotate at a low speed.

Next, set a mask time of 30 seconds and wait for the refrigerant pressure to balance between high and low pressures so that there is no refrigerant sound when switching the four-way valve, which will be described later.After that, the signal from output terminal _R3 switches from H to L. It is inverted to H by the inverter 22, the transistor 24 is turned off, the transistor 20 is also turned off, the four-way valve coil 19 is demagnetized, the four-way valve is switched, and the defrosting cycle (same as the cooling cycle) is started.

After setting a mask time of 6 seconds and waiting for the refrigerant pressure to balance between high and low pressures, the signal from the output terminal _R4 switches to H and is inverted to L by the inverter 23, turning on the transistor 25 and driving the compressor. The relay 17 is energized, the compressor is driven, and the defrosting operation begins. During such defrosting operation, as described above, the indoor fan motor 27 is rotated at a low speed to prevent blowing out of cold air, and the outdoor fan is stopped.

The frost adhering to the outdoor coil during defrosting operation is melted by the heat of condensation of the refrigerant, and when the outdoor coil temperature rises and reaches 5 degrees Celsius, contact 2 of the outdoor coil sensor
1 is opened, the transistor 14 is turned off, and the comparator 13 is short-circuited to ground, so the output from the output terminal _R2 is no longer applied to the input terminal _K1 , and this terminal _K1
becomes L. When this is determined and YES is output, the output terminal _R3 switches from L to H, which is inverted to H by the inverter 22, turning on the transistor 24, and turning on the transistor 20, which turns on the outdoor fan relay 18.
The four-way valve coil 19 is energized, the outdoor fan is restarted, the four-way valve is switched to the heating cycle, and the heating operation is restarted.

At this restart, the indoor fan motor 27 maintains low speed rotation to prevent cold air from being blown out, and the signal from the output terminal _R5 is output according to the subroutine flowchart of FIG. 2B when the indoor coil temperature reaches 30 degrees Celsius. is switched from H to L, and the speed control relay 28, which has been inverted to H by the inverter 26, is demagnetized and the indoor fan motor 27 is switched to high speed rotation.

As described in detail above, the device of the present invention is configured to start defrosting when the downward gradient change in indoor coil temperature of a heat pump air conditioner exceeds a set gradient, and has the following features.

As the outside air temperature drops, the indoor coil temperature follows and gradually drops, but once frost begins to form on the outdoor coil, the frost blocks heat exchange with the outside air and the indoor coil temperature drops abnormally. Since the phenomenon of frost formation is captured and detected, it is possible to reliably determine the presence or absence of frost formation.

In recent years, heat pump air conditioners have been equipped with an indoor coil sensor to prevent cold air from being blown into the room when heating operation starts, and manufacturing costs can be reduced by using this sensor in combination to detect frost formation. be able to.

In addition, when heating operation starts, the mask mechanism maintains heating operation for a minimum period of time (for example, 40 minutes) even if the outdoor coil is frosted, and prevents defrosting operation from starting at the same time as operation starts. be. Furthermore, during defrosting operation, the indoor fan is set at low speed to shorten defrosting time and prevent cold air at the same time.

Note that the accuracy of frost detection can be improved by reading the decreasing temperature gradient of the indoor coil temperature when the indoor coil temperature drops to the set temperature.

Furthermore, by incorporating into the device of the present invention whether the indoor coil temperature has fallen below the set temperature, the outdoor coil temperature has reached the set temperature, and whether the outdoor coil temperature has reached the set temperature or has already reached the set temperature, frosting can be prevented. The presence or absence of frost can be reconfirmed, and frost formation detection can be performed with even higher accuracy.

As described above, according to the present invention, it is possible to obtain a novel defrosting control device that is inexpensive and has high frost detection accuracy, and is thus useful.

[Brief explanation of the drawing]

Figure 1 is an electric circuit diagram showing one embodiment of the device of the present invention, Figures 2A and 2B are the main flowchart and subroutine flowchart, Figure 3 is a characteristic diagram of indoor coil temperature versus time, and Figure 4 is 2 is a block diagram showing the mechanism of the microcomputer shown in FIG. 1. FIG. 12... Indoor coil sensor, 21... Outdoor coil sensor.

Claims (1)

[Claims] 1 Heat pump type that uses a compressor, four-way valve, indoor coil, pressure reducer, and outdoor coil to configure a heating cycle and a cooling (defrosting) cycle, and has an indoor fan for the indoor coil and an outdoor fan for the outdoor coil. In a defrosting control device for an air conditioner, there is an indoor coil sensor that detects the indoor coil temperature, a timer mechanism that inputs the detected value of this sensor at regular intervals, and a slope of this value from the detected value input at every regular cycle. A calculation mechanism that calculates the change, a comparison mechanism that compares this change slope with a set slope, a mask mechanism that cuts off the output of the comparison mechanism for a predetermined period of time from the start of heating operation of the air conditioner, and a control mechanism that uses the output of the comparison mechanism to control the heating cycle. A defrosting control device for a heat pump air conditioner, comprising a defrosting control mechanism that switches to a defrosting cycle, stops an outdoor fan, and slows down an indoor fan.