JPH0684832B2 - Defroster for air conditioner - Google Patents

Description

The present invention relates to a defrosting device for an air conditioner such as an air heat source heat pump machine.

(Prior Art) In the conventional defroster, a predetermined time, for example 60 minutes, has elapsed regardless of the heating capacity decrease rate and the number of times of automatic heating start / stop, and the coil fin temperature from the defroster commander is -5
Defrosting (defrosting) was started when the temperature was below ℃ and the defrosting command signal was sent. However, this caused defrosting regardless of the rate of decrease in heating capacity. The energy efficiency ratio (EER) was low because the heating efficiency was poor because it often increased.

In order to improve such a point, a technique of detecting that the heating capacity has fallen to a certain extent and entering the defrost operation has been proposed, and is disclosed in Japanese Utility Model Application Laid-Open No. 57-16734.

This device calculates the heating capacity coefficient from the air temperature difference between the discharge air temperature and the intake air temperature of the utilization side coil and the air flow rate, and stores the value of the heating capacity coefficient due to the accumulation of frost on the heat source side coil. It is designed to start defrosting when it falls to a set rate with respect to a certain maximum heating capacity coefficient.By detecting the start of defrosting as a state of decreased heating capacity, defrosting starts too early. Not again
It is characterized by trying to get it done at an appropriate time, not late.

(Problems to be Solved by the Invention) Although it can be said that the above-mentioned device is appropriate in that the necessity of starting defrosting is captured by reducing the heating capacity, the point is that the heating capacity has fallen to a certain level. Since it is a detection, it will be too early or too late unless this reduction rate is selected to an appropriate value, and it is actually necessary to find the condition of the reduction rate necessary to keep the EER at the highest state. Is a difficult problem.Furthermore, it may malfunction due to a change in wind speed even if it is not frosted to the left due to the occurrence of an abnormal phenomenon such as snowfall.Especially, in the heating operation up to the start of defrosting. Since it is a control that has nothing to do with the progress, it is not easy to achieve proper defrosting while maintaining a high EER, which is determined by the balance between heating capacity and defrosting operation. It was.

The present invention has been made in response to such a problem, and the present invention is different from the conventional point control system in which the necessity of the defrost operation is determined by the current event that actually occurred. Calculated as the heating capacity integrated value corresponding to the actual value of the heating capacity based on the progress of the heating operation or the integrated value of the physical change amount corresponding to the heating capacity, and the average heating capacity is periodically repeated from this value. By calculating the defrost operation performed immediately before the heating operation and the heating operation performed before the heating operation, by considering the state of the defrost operation scheduled to be performed immediately after the current heating operation,
Let defrost be performed at an appropriate timing according to the actual heating operation, and enhance control reliability without malfunctioning during a transitional period that causes an indefinite fluctuation factor in the calculation of the heating capacity equivalent value immediately after startup. The purpose of this is to not only optimize the start of defrosting operation, but also improve the operating economy by maintaining the maximum EER value.

(Means for Solving Problems) The present invention is directed to an air conditioner in which heating operation is automatically started / stopped by an on / off command from a temperature controller. As shown in FIG. 1, as a defroster for an air conditioner, a temperature difference calculating means (1), a temperature difference peak value detecting means (2), a temperature difference integrating means (3), and a predicted defrost time calculating means (4). And an average heating capacity calculation means (5) and a comparison means (6).

The temperature difference calculating means (1) is _{arranged at} regular intervals from the outlet temperature (T _o ) and the inlet temperature (T _i ) of the fluid to be heated in the utilization side coil (11) during the heating operation time from the automatic start to the automatic stop. The temperature difference (ΔT _n ) is periodically calculated and stored.

The temperature difference peak value detection means (2) compares the previous temperature difference (ΔT _n-1 ) calculated by the temperature difference calculation means ( ₁ ) with the current temperature difference (ΔT _n ) to determine whether the heating operation is being performed. It has a configuration that detects the temperature difference peak value (ΔT _p ) that occurs for the first time after automatic startup and outputs an output.

After the temperature difference peak value detecting means (2) detects the temperature difference peak value (ΔT _p ) and outputs the output, the temperature difference integrating means (3) sequentially outputs the temperature difference calculating means (1). By integrating the calculated temperature difference values, the temperature difference integrated value (S _n ) is calculated and stored.

Next, the predicted defrost time calculating means (4) calculates the cumulative time (t _u ) of the heating operation performed from the end of the previous defrost operation to the start of the previous defrost operation and the time required for the previous defrost operation ( t _d ) and calculate
Based on the relationship between the two times (t _u ) and (t _d ), the predicted defrost operation time (t _f ) with respect to the heating operation time (t _f ) performed from the end of the previous defrost operation to the present
_dy ) is calculated.

Meanwhile, the average heating capacity calculating means (5), the temperature difference integrating means (3) the temperature difference integrated value calculated by the (S _n), the heating operation time (t _f) and the predicted defrost operation time (t
by dividing the sum of the _dy), having a structure for storing calculates an average heating capacity (Q _n).

Next, the comparison means (6) is the average heating capacity calculation means (5).
There has a configuration for outputting a defrosting signal when the current value is compared with the average heating capacity of the current calculated (Q _n) and the previous average heating capacity (Q _n-1) is small.

(Operation) In the present invention, the average heating capacity calculation means (5) and the comparison means (6)
Since the peak of the average heating capacity is captured by and the defrosting is performed when defrosting is required at this point, the heating capacity value is always kept at the maximum and the defrosting is effective. Can be done by

Therefore, even when the outside air temperature is low and it is dry, etc., since it is not allowed to enter the defrost while the heating capacity has the maximum value of the average heating capacity, there is a possibility that empty defrost will occur. It can be prevented.

Further, the present invention excludes the average heating capacity from the target of the average heating capacity calculation during the transitional period of this uncertain operation mode so that there is no influence of the low temperature difference in the initial stage when the heating operation is started by the automatic start. Since the heating operation capacity is calculated by predicting the defrost operation time scheduled to be performed immediately after the heating operation, the time for maximizing the average heating capacity can be accurately obtained according to the actual conditions.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a device circuit diagram of an air conditioner according to an embodiment of the present invention, which includes a compressor (7), a four-way switching valve (8), a heat source side coil (9), a capillary tube (10), and a use side. A well-known refrigeration circuit is configured by the coil (11) and the accumulator (12), and during heating operation, the refrigerant is circulated in the direction indicated by the solid line so that the utilization side coil (11) becomes a condenser and a heat source side coil ( 9) respectively to act on the evaporator, while at the time of cooling operation and defrosting operation, the refrigerant is circulated in the direction of the broken line arrow so that the heat source side coil (9) becomes the condenser and the utilization side coil ( It is needless to say that the refrigerant flow direction is switched by the switching operation of the four-way switching valve (8), and in the case of defrost operation, the heat source side fan (15) is operated. ) And the user side fan (16) It is intended Mel.

In FIG. 2, (13) is a first temperature detector that detects the air temperature at the outlet of the utilization side coil (11), and (14) is a second temperature detector that also detects the air temperature at the inlet. Both temperature detectors (13) and (14) form an input element of the temperature difference calculating means (1).

On the other hand, (17) is a deicer, which detects the coil inlet temperature of the heat source side coil (9), which becomes an evaporator during heating operation, and is -5 ° C or lower, or the built-in timer measures the heating operation time. It is a known defrost detector that emits a defrosting-required signal depending on whether any two hours have passed, and is connected to the input end of the defrost command means.

The electronic control circuit that controls defrosting control of the air conditioner having the above-described configuration is as schematically shown in FIG. 3, and (18) is a well-known microcomputer, which includes a CPU (19), a RAM (20), and
ROM (21) is a basic element.

A program for controlling the CPU (19) is written in the ROM (21), and the CPU (19) fetches external data from the input port (22) or RAM (2
0) and data is exchanged with the data processing, and the processed data is output to the output port (23) as needed.

The output port (23) receives the output port designation signal from the CPU (19), temporarily stores the data in the port, and outputs the analog signal to the four-way switching valve (8) via the D / A converter (27). It outputs to the solenoid (8 _S ) and the motor (16 _M ) of the fan (16) on the user side.

On the other hand, when the input port (22) receives an input port designation signal from the CPU (19), it takes in necessary information to the port, and the utilization side coil (1
Air outlet temperature (T _o ) in 1) is A / D converter (24)
As a digital signal, the air inlet temperature (T _i ) as a digital signal through the A / D converter (25), and the coil inlet temperature of the heat source side coil (9) detected by the deicer (17) is A / The signals are output to the input ports (22) as digital signals through the D converter (26).

Therefore, the program control in the microcomputer (18) is performed by the temperature difference calculating means (1), the temperature difference peak value detecting means (2), the temperature difference integrating means (3), the predicted defrost time calculating means (4), and the average. Heating capacity calculation means (5)
FIG. 4 is a flow chart showing a program written in the ROM (21), which constitutes the comparison means (6) and the defrosting instruction means.

Here, the theoretical basis for properly setting the timing of the defrosting start timing in the present invention will be described with reference to the diagrams starting from FIG. 7, but the way of determining the defrosting start timing is the use side coil during heating. Average heating capacity in (11),
That is, the average heating capacity of the air conditioner is greatly affected.To improve the EER, the average heating capacity, that is, the average heating capacity from the start of the defrosting operation to the end of the next defrosting operation is used. The average heating capacity (Q _n ) when the user side fan (16) is stopped at the time of defrosting in an air conditioner that uses an air heat source and an air conditioner must satisfy the condition that can maximize the value. It becomes an expression.

However, ΔT _m : Average temperature difference (℃) t _h : Heating operation time (H _r ) C _p : Air specific heat (Kcal / kg ・ ° C) r: Air specific weight (kg / m ² ) w: Air volume (m ² / H _r) Q _n: average heating capacity _{(Kcal / H r) t d} : defrost operation time (H _r) the formula (i) is C _p, r, since w is almost constant, Q _n is ([Delta] t , T _h , t _d ).

By the way, when the heating operation and the defrosting operation are alternately repeated, the heating capacity, that is, the use side coil (11)
The value is proportional to the temperature difference (ΔT), which is the difference between the air outlet temperature (T _o ) and the air inlet temperature (T _i ) during heating, but the state that changes with the passage of time is shown in Fig. 7. As shown, the transition of the temperature difference (ΔT) is zero at the start of heating operation (T _o ), and the difference increases with the operation and reaches the maximum temperature difference value (ΔT _m ). Next, since the capacity decreases as the frost adheres to and grows on the heat source side coil (9), the temperature difference (ΔT) gradually decreases and becomes close to saturation.

Therefore, from the temperature difference (ΔT) read every predetermined time, for example, every 30 seconds or 1 minute from the start of the heating operation, the integrated value (S) up to the present time with the start of the operation as the base point, that is, the heating capacity After the heating capacity value (S), which is the integrated value obtained by integrating the equivalent values, is sequentially calculated and the result shown in the diagram in FIG. 8 is obtained as the first stage, the heating capacity value (S )
The average heating capacity (Q _n ) is sequentially calculated by dividing the heating operation time (t _f ) from the start of heating operation by the sum of the defrosting time (t _d ) of the defrosting operation performed immediately after that. The result shown in the diagram of FIG. 9 is obtained as the second stage.

By the way, as is clear from the above-mentioned diagrams, the state of change of the heating capacity value (S) from the start of heating operation to the maximum temperature difference (ΔT _m ), that is, the maximum heating capacity value reaches a steep curve at a low level. And, after reaching the maximum heating capacity value, the capacity decline period is a high level and becomes a gentle curve,
Then, where the heating capacity value is low and saturated due to frost formation, the curve becomes abrupt at a high level.

Therefore, as shown in FIG. 9, the average heating capacity (Q _n ) becomes maximum immediately before the time when defrosting is required and the defrosting operation is required, and then decreases.

As is clear from the above points, if the defrosting is performed by determining the time when the average heating capacity (Q _n ) calculated in a certain period of time is the maximum, the EER is kept at the maximum and the heating operation and the defrosting operation are performed. it is possible to perform the preparative, in short when calculating the periodic average heating capacity (Q _n) to find conditions under which the value is maximum, becomes smaller towards the current calculated value than the previous calculated value It means that you can judge that.

The content described above is for the case where the air conditioner operates continuously until defrosting without turning the compressor on and off, but the compressor automatically starts and stops according to the on / off command from the temperature controller. If this is the case, we need to consider how to deal with it.

On the other hand, in order to stop the heating operation and switch to the defrosting operation at the timing, it is necessary to predict the defrosting time to be performed thereafter and calculate the average heating capacity.

First, the correspondence when the heating operation is automatically started and stopped will be described. When the heating operation is started by the ON command from the temperature controller, the temperature difference (ΔT) is from 0 ° C to a short time (several minutes) as shown in Fig. 10. ) Of the peak value (ΔT _p )
After that, when the temperature difference gradually decreases and the temperature difference (ΔT) becomes smaller, the heating operation is stopped by the OFF command.

By the way, it is a transitional period until reaching the peak value (ΔT _p ) immediately after the start of moving, and even if the part in the low temperature difference region is used as the calculation element of the average heating capacity, an inaccurate result will be obtained. In addition, the operation interruption period from automatic stop to automatic start also needs to be excluded from the time factor of heating operation.

Therefore, the temperature difference (ΔT) after automatic startup is the peak value (ΔT _p ).
Temperature difference integrated values (S ₁ ), (S ₂ ), ...
Based on this, it is desirable to calculate the average heating capacity (Q _n ) only when the heating operation is actually performed.

The following can be said about the prediction of the defrosting time.

When the time required for the defrosting operation to be performed after changing the heating operation time to various values with the outside air temperature kept constant was measured in the test room, it was found that the heating operation time (t _u ) The result is approximately proportional to the operation time (t _d ) of the defrosting operation performed in the above.

Therefore, if the previous heating operation time (t _un-1 ) and the previous defrosting operation time (t _dn-1 ) are known, the defrosting operation is now performed during the heating operation after a certain time (t _un ) has elapsed. If you switch to
It is possible to find out what the predicted defrost operation time (t _dy ) is.

That is, However, in reality, immediately after switching from the heating operation to the defrosting operation, the heat source side coil is switched from the evaporator to the condenser to operate, and a delay occurs due to the heat capacity. It is possible to consider a certain value that requires a certain degree and is unrelated to the elapsed time of the heating operation immediately before.

From the above, it is desirable to modify the equation (b) to the following equation (c).

A flowchart for performing the defrosting operation based on the determination process described above will be described with reference to FIGS. 4 to 6.

The heating operation switch is turned on to start heating the air conditioner (step), and at the same time, initial setting is performed (step).

In this initial setting, the electronic timer is reset to zero, which is the starting point of the heating operation time (t _f ), the temperature difference integrated value (S) and the average heating capacity (Q) are set to zero, respectively, and when the operation is started. Since the defrost operation has never been performed in, the appropriate defrosting time (t _d ) such as 5 minutes is set as one of the conditions for taking the subsequent timing.
It means that the flag (Flg) is set to 0 and they are stored in the microcomputer (18).

Thus, the electronic timer starts timing and the measurement flow (step) shown in FIG. 5 is entered until the heating operation time (t _f ) reaches 20 minutes (step).

That is, the heating operation state is first checked (step), and the temperature of the air outlet temperature (T _o ) and the air inlet temperature (T _i ) are counted every time a certain time (eg, 1 minute) is counted (step). The difference (ΔT _n ) is calculated and stored (step).

This step corresponds to the processing function of the temperature difference calculating means (1).

The operation mode is unstable until about 20 minutes have passed from the start of the operation (there is an uncertain factor), so during this period, the defrosting operation is prevented from entering.

While calculating the temperature difference (ΔT _n ) every minute, compare the current temperature difference (ΔT _n ) with the previous temperature difference (ΔT _n-1 ) (step), and if ΔT _n <ΔT _n-1 If there is, it is the temperature difference peak value (ΔT _p ) that occurs for the first time, so temperature difference integration is performed to sum the temperature difference value (ΔT _n ) calculated by the temperature difference calculation means (1) (step), and the flag ( Flg) is 0 (step), so the average heating capacity (Q _n ) is the _sum of the set defrost time (t _d = 5 minutes) and the heating operation time (t _f ) and the integrated temperature difference value (S _n ). Obtain by dividing (step).

Incidentally, the step corresponds to each processing function of the temperature difference peak value detecting means (2), the step corresponds to the temperature difference integrating means (3), and the step corresponds to each processing function of the average heating capacity calculating means (5).

In this way, heating operation continues and the value of continuous operation time is 20
If it is checked that the time exceeds the minute and is within 120 minutes (step), the average heating capacity (Q _n ) calculated this time is compared with the previous value (Q _n-1 ) every minute during that time ( Step).

If the comparison result is Q _n ≧ Q _n-1 , the measurement flow (step) is reached, while if Q _n <Q _n-1 , the average heating capacity (Q _n ) is maximum at that time. This means that the value has passed the value and is in the state of decreasing, so the defrosting signal is output from the comparing means (6).

The steps correspond to the processing function of the comparison means (6).

In this state, if the coil temperature of the heat source side coil (9) is -5 ° C or higher and the deicer (17) does not emit the defrost signal (step), the measurement flow (step) is continued, but When a frost signal is emitted, it shifts to defrost flow (step).

This defrost flow is as shown in FIG. 6, and the heating cycle is switched to the cooling cycle, and the heating operation time (t _f ) in the electronic timer is changed to the current value (t _u ).
After performing the initial setting (step) that is fixed to 1, and resets the defrost operation time (t _d ) to zero, the defrost operation time is measured (step) in units of 1 minute.

Thus, as a result of the defrosting operation by the cooling cycle being performed and the frost being melted, the deicer (17) detects that the coil temperature is 15 ° C or higher due to the completion of defrosting, and issues a defrost release signal (step). , The cooling cycle is switched to the heating cycle, and the process goes to step (c) to calculate (t _dn-1 -1) / t _un-1 = A, and then the heating operation time (t _u ) Is reset to zero, the temperature difference integrated value (S) and the average heating capacity value (Q) are reset to zero, and a flag (Flg) is set.
Is set to 1 (step).

In the step, if it is checked that two hours have elapsed from the start of the heating operation and that the defroster (17) is outputting a frost detection signal, Q _n <in the microcomputer (18). This is a check function for forcibly entering the defrosting operation even if the calculation result of Q _n-1 is not obtained.

In this way, one cycle consisting of the heating operation and the defrosting operation is completed, and the operation from step is performed again,
The measurement flow (step) from the second cycle is
In FIG. 5, since the flag is 1 at step, the sequence shifts to the right half sequence operation.

First, in step, the calculation of the formula (C) is performed to calculate the predicted defrost operation time (t _dy ) when the heating operation is switched to the defrosting operation at the current time.

This step naturally corresponds to the processing function of the predicted defrost time calculation means (4).

The above calculation result may be directly brought into the calculation of the step, but the time required for the previous defrosting (t _d ) after checking from step to step considering the safety level
It is a preferred means compared to predicted defrosting operation time (t _dy defines upper and lower limit values to fit within the 0.5t _d ≦ t _dy ≦ 1.5t _d and.

Thus, when the calculation of the predicted defrost operation time (t _dy ) is completed, the process proceeds to the step of the processing procedure by the average heating capacity calculation means (5).

That is, the average heating capacity (Q _n ) is calculated by dividing the temperature difference integrated value (S _n ) up to the present by the sum of the current heating operation integrated time (t _f ) and the predicted defrost operation time (t _dy ). It is calculated.

It is the same as in the case of the first cycle that this calculation procedure is performed until the comparison means (6) checks Q _n <Q _n-1 and switches to the defrosting operation.

In this way, the defrosting operation is performed by checking the point at which the average heating capacity (Q _n ) becomes maximum, so that it is possible to perform the alternate operation of heating and defrosting at the highest EER state.

The example explained above is for the case of an air-cooled air-conditioning system that is generally called an air-cooled air conditioner, and it is considered that there is no negative factor for the heating capacity by stopping the indoor fan during defrost operation. On the other hand, in the case of an air heat source / water utilization method called an air-cooled chiller, it is necessary to consider the loss capacity to the heating capacity due to the fact that the hot water is cooled during the defrost operation, In that case, it is assumed that the temperature of the hot water drops by about 5 ° C., and the heating capacity commensurate with this temperature drop is subtracted, and otherwise the same calculation as in the above example may be performed.

(Effects of the Invention) As described above, the present invention finds a state in which the average heating capacity has the maximum value by calculation with respect to the phenomenon of a decrease in heating capacity due to frost formation, and performs defrosting operation according to this state. Since the switching control is performed, there is no need to start defrosting quickly even if there is room in heating capacity, or delay defrosting even if the capacity is low, and consider the surrounding conditions. After that, it becomes possible to take the optimum defrosting timing, thus EER (energy effective ratio) during heating operation.
Defrosting is possible while increasing the maximum.

Further, in the present invention, in the case of heating operation in which automatic start / stop is repeated, a transition period with many uncertain factors immediately after startup and an operation interruption period are one of the factors for calculating the average heating capacity (Q _n ) Since it is excluded from the above, it is possible to calculate the capacity accurately and according to the actual condition, and it is a suitable device to be applied to this type of air conditioner.

In addition, the time required for the defrosting operation immediately after the heating operation, which is the basis for capacity calculation, can be accurately predicted, and the time to find the maximum value of the average heating capacity can be calculated reasonably and reliably. Defrosting control that is not significantly affected by the operation progress of

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a device circuit diagram according to an embodiment of the present invention, FIG. 3 is an electronic control circuit diagram for defrost control, and FIGS. 4 to 6 are Flowchart showing the defrosting control mode, FIGS. 7 to 9 are diagrams showing changes in heating capacity, temperature difference integrated value and average heating capacity with respect to operating time, and FIGS. 10 and 11 are temperature difference changes in heating operation. It is a figure which shows the time-dependent state of and an integral average heating capacity. (1) ... Temperature difference calculation means, (2) ... Temperature difference peak value detection means, (3) ... Temperature difference integration means, (4) ... Predicted defrost time calculation means, (5) ... Average heating capacity calculation means, 6) ... Comparison means, (11) ... use side coil.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Takeo Ueno 1304 Kanaoka-cho, Sakai City, Osaka Daikin Industry Co., Ltd.Kanaoka Plant, Sakai Factory (72) Masami Horiuchi 1304, Kanaoka-cho, Sakai City, Osaka Daikin Industry Co., Ltd. Sakai Plant Kanaoka Factory

Claims (1)

[Claims] In an air conditioner in which heating operation is automatically started / stopped by a command from a temperature controller, an outlet temperature of a fluid to be heated in a utilization side coil (11) during a heating operation time from automatic start to automatic stop. (T _o ) and inlet temperature (T _i ) with a periodic temperature difference (ΔT _n ) at regular intervals
And a temperature difference calculation unit (1) that calculates and stores the temperature difference (Δ) calculated by the temperature difference calculation unit (1).
T _n-1 ) and the current temperature difference (ΔT _n ) are compared with each other, and the temperature difference peak value detecting means (2) that outputs the temperature difference peak value (ΔT _p ) that occurs for the first time after the automatic start of the heating operation is detected. ) And each temperature difference value sequentially calculated by the temperature difference calculating means (1) after the temperature difference peak value detecting means (2) detects the temperature difference peak value (ΔT _p ) and outputs an output. The temperature difference integrating means (3) that calculates and stores the temperature difference integrated value (S _n ) by integrating the temperature difference and the heating operation performed between the end of the previous defrost operation and the start of the previous defrost operation. The accumulated time (t _u ) and the time (t _d ) required for the previous defrost operation were calculated, and the previous defrost operation was completed based on the relationship between both times (t _u ) and (t _d ). prediction for heating operation time was made up later from the current (t _f) Defurosu The operating time (t _dy) predicted defrosting time calculating means for calculating a (4), the temperature difference integrating means (3) the temperature difference integrated value calculated by the (S _n), the heating operation time (t _f) The average heating capacity calculation means (5) for calculating and storing the average heating capacity (Q _n ) by dividing by the sum of the estimated defrost operation time (t _dy ) and the average heating capacity calculation means (5) The average heating capacity (Q _n ) of this time is compared with the average heating capacity (Q _n-1 ) of the previous time, and a comparing means (6) that outputs a defrost signal when the current value is small is used. A defrosting device for air conditioners.