JPH0437340B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an air-source heat pump type air conditioner in which a compressor, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger are connected in sequence. This relates to a defrosting operation control device for a machine.

[Prior art and problems to be solved by the invention]

BACKGROUND ART Air conditioners with a heat pump type refrigeration cycle that are capable of not only cooling operation but also heating operation are becoming increasingly used.

By the way, in the heating operation described above, since the refrigerant evaporates in the outdoor heat exchanger, moisture in the air condenses and adheres to the heat exchanger. When this moisture freezes due to a drop in outside temperature, it turns into frost and impedes heat exchange, so it is necessary to defrost it as appropriate.

Refrigeration cycles for removing frost on the outdoor heat exchanger include a reverse cycle type, a hot gas bypass cycle type, and a heating defrost cycle type.

In the reverse cycle type, when switching from heating operation to defrosting operation, the four-way valve is switched to change the flow direction of the refrigerant and reverse the high pressure and low pressure. In this way, high-pressure gas flows through the outdoor heat exchanger, and this heat melts the frost.

In the hot gas bypass cycle type, defrosting is performed while heating operation is performed. solenoid valve
Turn it on to create a bypass cycle of high-temperature, high-pressure gas to defrost.

In the heating defrost cycle type, an electric valve with a solenoid valve function is used as the flow control valve, and during defrosting, the valve is fully opened by the defrost signal, and the flow control valve functions as a throttle function (expansion valve). Instead, it functions as a solenoid valve and moves liquid refrigerant.

As mentioned above, there are various types of refrigeration cycles for defrosting, but all of them have some kind of frost detection means, and the defrosting operation is performed based on the signal from the frost detection means.

Conventionally, one method for detecting frost formation and starting a defrosting operation is to use a combination of the pipe temperature of an outdoor heat exchanger, the outside air temperature, and a timer. In this method, the piping temperature of the outdoor heat exchanger and the outside air temperature are detected, and frost formation is detected using a predetermined outside air versus outdoor heat exchanger temperature characteristic. After a predetermined period of time, if the temperature is higher than the set temperature, which changes depending on the outside temperature,
The heating operation continues and waits until the temperature drops below the set temperature.

In this method, defrosting is not performed within a certain period of time after the start of operation, and even if the outside air temperature is low and no frost has formed, if the temperature and time requirements are met, defrosting is performed. There is a problem in that it is difficult to drive, which is contrary to energy saving and also impairs comfort.

In addition, as proposed in Japanese Patent Application Laid-Open No. 59-46438, the start of defrosting operation is determined based on the outdoor heat exchanger piping temperature and outside air relative humidity, and the outdoor heat exchanger piping temperature is Some devices start defrosting operation when the temperature is below a certain level and the relative humidity is above a certain value. However, with this method, if the outside air relative humidity has not fallen below a certain value, when heating operation is resumed after defrosting, defrosting operation will start again, so heating operation and defrosting operation are repeated ( This results in hunting (hunting) operation, which is difficult to implement.

Therefore, a method of starting defrosting operation after a certain period of time after the start of frost formation is considered, but this method always has a negative impact on comfort and operational efficiency because the speed of frost formation differs depending on the situation after the start of frost formation. Defrosting operation cannot be started with the optimum frost amount.

Therefore, in view of the above-mentioned conventional problems, the present invention provides a defrosting operation control device that improves comfort and operational efficiency by causing an air conditioner to start defrosting operation at an appropriate time. The purpose is to

[Means for solving problems]

In order to achieve the above object, the defrosting operation control device according to the present invention includes an outdoor heat exchanger temperature detection section 1 that detects the temperature of the outdoor heat exchanger, as shown in the basic configuration diagram of FIG. It is determined that the temperature detected by an outside air humidity detection section 2 that detects the humidity of outside air and the outdoor heat exchanger temperature detection section is below zero degrees, and that the humidity detected by the outside air humidity detection section is above a predetermined value. a determining means 3; a counting means 4 that performs counting when the determining means 3 determines that the temperature is below zero and the humidity is above a predetermined value; and the counting means 4 that performs counting based on the detected temperature and the detected humidity. means 4a for determining the counting speed of the counting means 4, the amount of frost formation is determined from the count value of the counting means 4, and when the value reaches a predetermined value, the defrosting operation of the air conditioner is started. It is a feature.

[Effect]

Figure 2 shows the characteristics of outdoor heat exchanger temperature vs. operating time (t) until the amount of frost builds up, for example, 500g, for an outdoor heat exchanger of an air conditioner, and outside air humidity is also a variable. It is considered as.

As can be seen from the figure, the higher the outdoor heat exchanger temperature and the higher the outside air humidity, the faster the rate of frost formation, so the time t until a constant amount of frost formation is reached is shorter. In other words, the time it takes to reach a certain amount of frost is t
Then, t is expressed as a function of the outdoor heat exchanger temperature (T _E ) and the outside air relative humidity (H _A ).

t=F(T _E , H _A ) In the defrosting operation control device according to the present invention, in view of the above-mentioned phenomenon, the determination means 3 determines in the outdoor heat exchanger temperature detection section that the frost formation condition is satisfied. Detection is performed by determining that the detected temperature is below zero degrees and the humidity detected by the outside air humidity detection section is above a predetermined value, and based on this detection, the counting means 4 is caused to count, and the count is The counting speed determining means 4a determines the speed based on the ever-changing temperature of the outdoor heat exchanger and the humidity of the outside air.

Therefore, the count value of the counting means 4 does not change under conditions where frosting does not occur, and changes quickly under conditions where frosting is likely to occur, and slowly under conditions where frosting is difficult to occur. Become something.

Then, when this count value reaches a predetermined value, it is assumed that the amount of frost has reached the predetermined amount and the defrosting operation is started, so that the defrosting operation can always be started in the optimal condition. ing.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 is a block diagram showing an embodiment of the defrosting operation control device according to the present invention configured using a 1-chip microcomputer (μCON) 10. In the figure, 1 and 2 are for outdoor heat exchanger temperature detection, respectively. and an outside air humidity detection section. The output signals of both detectors 1 and 2 are input to an analog-to-digital (A-D) converter 13 via amplification widths 11 and 12, respectively. A-D converter 13 is μCON
Based on the sampling signal from 10, the input analog signal is converted into a digital signal and output, and this is applied to the input of μCON 10, respectively.

μCON10 has an arithmetic processing unit (ALU), ROM,
It has RAM, input/output ports, etc., and is equipped with ROM in advance.
It performs the work described later in accordance with the program stored in the ROM, controls the A-D converter 13, inputs digital data from the A-D converter 13, and stores the digital data in advance in the ROM. It reads certain data, makes judgments about the data under specific conditions, performs logical operations based on these, and sends the results to the output section 14.

The output unit 14 is composed of TTL, relay contacts, etc., and sends a defrost start signal and a defrost end signal to a control device of an air conditioner (not shown).

The operation of the above configuration will be explained with reference to the flowchart of the work performed by μCON 10 according to the program shown in FIG.

For example, μCON10 initializes in step S1 after being started by turning on the power.
After that, a signal is sent to the A-D converter 13, and the step
In step S2, data regarding the outside air humidity from the outside air humidity detection section 2 is read, and in step S3, data regarding the outdoor heat exchanger temperature is read. Then, with both data read above,
In step S4, timer interrupt cycle data is retrieved by referring to the timer interrupt cycle data table in the ROM, and this is used in the next step S5.
This data is set in the timer register in μCON 10, and this data determines the execution point of the timer interrupt routine.

The timer interrupt cycle data table stored in the ROM is based on the outdoor heat exchanger temperature T determined from the graph in Figure 2 which shows the time required for a certain amount of frost to form with respect to outdoor heat exchanger temperature and outdoor air humidity. _E is created based on the graph in Figure 5 which shows the outside air humidity and timer interrupt cycle.
The purpose can be achieved by creating a table for each temperature T _E below 0℃ and 1℃.

The timer interrupt routine is as shown in FIG. 4b, and is executed at any time when the timer that has set the data times out, and the main routine of FIG. 4a is interrupted at this time of execution. In the first step S'1 of the subroutine, it is determined whether the outside air humidity read in step S2 is 60% RH or more, and if the determination is NO, the process returns to the original main routine. Then, if the determination is YES, in the second step S'2, it is determined whether the outdoor heat exchanger temperature read in step S3 is below 0°C, and if the determination is NO, the original main routine is resumed. Return to Then, if the determination is YES, in the third step S'3, it is determined whether the air conditioner is currently in defrosting operation or not.
If YES, the process returns to the main routine, and if NO, the counter value is incremented by 1 in the next fourth step S'4, and then the process returns to the main routine.

After the data is set in the timer register in step S5, the process advances to the next step S6, where it is determined whether the counter has overflowed or not. The capacity of this counter is determined according to the periodic data table and the characteristics of the air conditioner to which it is applied.

If the judgment in step S6 is NO, step
Returning to S2, the above steps S2 to S6 are executed again, and this is repeated until the determination becomes YES.
If the determination is YES, the process advances to step S7, where a defrosting start signal is sent to the output section 14. In response, the output unit 14 outputs a signal that causes the air conditioner to start its defrosting operation.

Subsequently, in step S8, data regarding the outdoor heat exchanger temperature T _E is read, and in step S9 it is determined whether or not the read temperature T _E has reached the defrosting end temperature. While the determination at step S9 is NO, steps S7 to S9 are repeated, and when the determination is YES, the next step S1 is executed.
At 0, a defrosting end signal is sent to the output unit 14,
Stop the defrosting operation of the air conditioner. Thereafter, the counter is reset in step S11, and the process returns to step S2.

For example, if the basic clock of the μCON10 timer is 1ms, when the data at point a in Figure 5 is read, the count period corresponding to that data is 200μs, so the timer interrupt period data table The above value is set to 3, for example, so that a timer interrupt is generated by counting three basic clocks. Therefore, omitted
When interrupting the subroutine every 100 μS, if steps S′1 and S′2 are YES and the judgment of S′3 is
If NO, the counter will be incremented by 1,
The value of the counter is a predetermined amount, that is, in this example,
When the temperature reaches 18000, it is assumed that the amount of frost has reached a predetermined amount and the defrosting operation is started.

In short, the counter is designed to count only when frost is progressing, at a cycle that corresponds to the speed of frost formation, so the amount of frost can be determined from the counted value. When the amount of frost reaches a predetermined value, it is known that the amount of frosting has reached the amount at which defrosting should be started, and the defrosting operation can be started.

Note that in the above example, the count period of the counter, that is, the timer interrupt period, is changed by making it correspond to the change in input data.
For example, this may be done without using such an interrupt by changing the predetermined value at which the counter counts up when the condition is satisfied within a predetermined width based on the input data.

FIG. 6 is a block diagram showing another embodiment of the defrosting operation control device according to the present invention, which is constructed by a discrete circuit in place of the A-D converter 13 and μCON 10 in FIG. The same parts are given the same reference numerals.

In the figure, 20a is voltage-frequency (V-
F) is a converter, which generates a pulse train with a frequency proportional to the voltage applied to its input, and which connects the AND gate 2
Send to 0b. 20c is a function generator, which converts the humidity signal output from the amplifier 12 and the temperature signal output from the amplifier 11 into the V-F converter 20.
The conversion is performed so as to match the input level of a. The fact that the time t required to reach a certain amount of frost formation is short means that the converted frequency is high. In terms of the relationship with the input applied voltage, the higher the outdoor heat exchanger temperature and the higher the outside air humidity, the higher the frequency, and therefore the higher the input applied voltage. This can be illustrated as shown in FIG. 7. V
- If the F converter 20a is one with a 1KHz/V function, for example, at point a in FIG.
It oscillates at 4.68KHz and 2.15KHz at point b.

The comparator 20d compares the humidity signal output from the amplifier 12 with the set reference voltage corresponding to humidity 60% RH, and if the outside air humidity is lower than the set humidity, sends an L level, and if higher, sends an H level to the AND gate 20b. do.

Note that this 60% RH standard is based on an outside humidity of 60%.
This setting was made because if it is lower than %RH, no growth will occur even if frost forms.

Similarly, the comparator 20e compares the temperature signal output from the amplifier 11 with the set reference voltage corresponding to 0°C, and outputs an L level if the outdoor heat exchanger temperature is higher than the set temperature, and an H level if it is lower.
It is sent to gate 20b.

The AND gate 20b operates only when the V-F
The pulse waveform generated by the converter 20a is used as a clock and sent to the counter 20f.

For example, if a 24-stage ripple binary counter is used as the counter 20f, 2 ²⁴ =
Output is produced by inputting 16777216 clock pulses.

For example, in the case of point a in Figure 7 (T _E = -5℃, 85%RH), 4.68V input causes 4.68KHz oscillation, and overflow occurs in 1/4.68KHz x 16777216 ≒ 3585 seconds ≒ 60 minutes. , point b (T _E = -5℃, 75
%RH), 2.15V input results in 2.15KHz oscillation, and overflow occurs in 1/2.15KHz x 16777216 ≒ 7803 seconds ≒ 130 minutes.

As described above, when the count ends due to overflow, the next stage latch 20g is set and the output section 14
The output unit 14 sends a defrosting start signal to the air conditioner.

The comparator 20h compares the temperature signal output from the amplifier 11 with a set reference voltage corresponding to approximately 10°C, and outputs an H level when the outdoor heat exchanger temperature becomes higher than the defrosting end temperature. Time is L
bring out the level.

The monomulti 20i detects the rising signal of the comparator 20h (positive edge) and generates a one-shot pulse. The power-on reset generating section 20j generates a one-shot pulse when the power is turned on. The OR gate 20k takes the OR of the two one-shot pulses and outputs the OR gate to the counter 20f.
and reset the latch 20g. Thereby, the air conditioner receives the defrosting end signal, ends the defrosting cycle, and returns to heating operation.

〔effect〕

As explained above, according to the present invention, during heating operation when frost formation occurs on the outdoor heat exchanger, counting is performed at a rate determined by the outdoor heat exchanger temperature and the outside air humidity, which determine the occurrence and speed of frost formation. By using this count value, it is detected that the amount of frost has reached a certain value, and the defrosting operation is performed.
It is possible to detect false frost formation and prevent empty defrosting operation, and it is possible to improve comfort and operational efficiency.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of the device according to the present invention, Fig. 2 is a graph showing the time required to reach a certain amount of frost with respect to outdoor heat exchanger temperature and outside air humidity, and Fig. 3 is a diagram showing the basic configuration of the device according to the present invention. 4 is a flowchart for explaining the operation of the device shown in FIG. 3, FIG. 5 is a characteristic graph used in the embodiment shown in FIG. 4, and FIG. 6 is a device according to the present invention. A block diagram showing another embodiment of
The figure is a characteristic graph used in the embodiment of FIG. DESCRIPTION OF SYMBOLS 1...Outdoor heat exchanger temperature detection section, 2...Outside air humidity detection section, 3...Determination means, 4...Counting means, 4a...Speed determining means.

Claims (1)

[Scope of Claims] 1. In an air conditioner in which a compressor, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger are connected in sequence, the outdoor heat exchanger temperature detects the temperature of the outdoor heat exchanger. a detection unit; an outside air humidity detection unit that detects the temperature of outside air; and the temperature detected by the outdoor heat exchanger temperature detection unit is below zero degrees, and the humidity detected by the outside air humidity detection unit is greater than or equal to a predetermined value. determining means for determining the detected temperature; and counting means for performing a count when the determining means determines that the temperature is below zero and the humidity is above a predetermined value; means for determining a counting speed, the amount of frost formation is known from the count value of the counting means, and when the value reaches a predetermined value, defrosting operation of the air conditioner is started. Defrosting operation control device.