JPS63204052A - Defrosting device in air conditioner - Google Patents

Abstract

PURPOSE:To estimate next defrosting operation time to calculate a mean heating capability, to find out a condition where the means heating capability shows its maximum value, to change over it to a defrosting operation in response to the former condition and to enable a proper defrosting timing to be carried out by a method wherein each of calculating means for a calculating heating capability, an estimated defrosting time and a mean heating capability and a comparing means are provided. CONSTITUTION:Means 1 for calculating a calculated heating capability may calculate periodically a calculated heating capability Sn from a heating starting time just after a completion of a defrosting operation in a utilization coil 9 during heating operation and then stores the capability. An estimated defrosting time calculation means 2 may calculate, under a primary function, an estimated defrosting operation time (tdy) in respect to a heating operation time (tf) performed from a completion of a previous defrosting operation up to the present time in response to a relation between the calculated time of heating operation from the completion of the previous last defrosting operation to the starting of the previous defrosting operation. Means 3 for calculating a mean heating capability divides the calculated heating capability Sn by a sum of times (tf) and (tdy) to calculate a mean heating capability Qn and then stores it. A comparing means 4 may compare a present value and a previous value of the mean heating capability to each other. When the present value is smaller than the previous value, it amy output a defrosting signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a defrosting device for an air conditioner such as an air source heat pump machine.

(Prior art) A conventional defrosting device has no relation to the heating capacity reduction rate when a predetermined period of time, for example 60 minutes has elapsed, and the defrost command indicates that the coil fin temperature is, for example, -5°C or lower. Defrost was started when a defrost command signal was sent by the heating system, but in this case, defrosting was performed regardless of the rate of decrease in heating capacity, so if the decrease in capacity became large, defrost was started. The energy efficiency ratio (EER) was low because of the large amount of electricity and poor heating efficiency.

In order to improve this problem, a technique has been proposed that detects when the heating capacity has decreased to a certain extent and enters defrost operation, and is disclosed in Japanese Utility Model Application Publication No. 57-16734 and others.

This device calculates the heating capacity coefficient from the air temperature difference between the discharge air temperature and intake air temperature of the user side coil and the air flow velocity, and stores the value of the heating capacity coefficient due to the accumulation of frost on the heat source side coil. Defrosting is started when the maximum heating capacity coefficient decreases to a set percentage, and by detecting the start of defrosting as a state of reduced heating capacity, it is possible to prevent defrosting from starting too early. It is also characterized by the fact that it is attempted to be carried out at an appropriate time rather than too late.

(Problems to be Solved by the Invention) The above-mentioned device can be said to be appropriate in that it detects the necessity of starting defrost as a decrease in heating capacity, but it detects the state where the heating capacity has decreased to a certain state as a point. Therefore, if this rate of decrease is not selected appropriately, the result will be too early or too late, and it is actually difficult to find the conditions for the rate of decrease necessary to maintain the EER at its highest level. This is a difficult problem, and furthermore, due to abnormal phenomena such as snowfall, there may be changes in wind speed even when frost has not formed to the left, causing malfunctions.In particular, the process of heating operation up to the start of defrost Since the control has no relationship at all with the heating capacity and the defrost operation, it has not been easy to perform the defrost appropriately while keeping the EER high, which is determined by the conflict between the heating capacity and the defrost operation.

The present invention has been made to address these problems, and unlike the conventional point control method, which determines the necessity of defrost operation based on the current event that actually occurs, the present invention Calculate the actual value of heating operation capacity based on the progress of heating operation or the integrated value of heating capacity corresponding to the integral value of the amount of physical change that changes in response to heating capacity, and periodically calculate the average heating capacity from this value. The gist is a continuous control method that attempts to perform defrosting at the appropriate timing according to the actual heating operation by repeatedly calculating and taking into account the status of the defrost operation that was performed immediately before heating operation. In this way, the purpose is not only to optimize the start of defrosting operation but also to improve operational economy by maintaining the maximum value of HEH.

(Means for Solving the Problems) Therefore, as shown in FIG. 1, the present invention provides a defrosting device for an air conditioner that includes an integrated heating capacity calculating means (1) and a predicted defrosting time calculating means (2). , average heating capacity calculation means (3),
The comparison means (4) is also provided.

Therefore, the cumulative heating capacity calculation means (1) periodically calculates the cumulative heating capacity (Sn) at fixed time intervals from the start of the heating operation immediately after the end of defrosting in the user-side coil (9) during the heating operation. It has a configuration for storing information.

Next, the predicted defrosting time calculation means (2) calculates the cumulative heating operation time (tu) from the end of the previous defrosting operation to the start of the previous defrosting operation and the previous defrosting operation time (ta). Based on the relationship, the predicted defrosting operation time (tdy) for the heating operation time (tr) performed from the end of the previous defrosting operation to the present time is calculated in a linear manner.

Further, the average heating capacity calculation means (3) calculates the cumulative heating capacity (Sn) calculated by the cumulative heating capacity calculation means (1),
The heating operation time (tu) and the predicted defrosting operation time (t
dy), the average heating capacity (Q
It has a configuration for calculating and storing n).

On the other hand, the comparison means (4) is the average heating capacity calculation means (
3) has a configuration that compares the current value (Qn) and the previous value (Qfi-1) of the average heating capacity (Q, ) calculated by 3) and outputs a defrosting signal when the current value is small. .

(Function) The present invention provides an average heating capacity calculation means (3) and a comparison means (4).
The system determines the point in time when the average heating capacity peaks, and if defrosting is required at this point, defrost is performed, so the heating capacity value is always maintained at the maximum while defrosting is performed effectively. It is possible to make it happen.

Furthermore, by accurately calculating the predicted defrosting operation time (t4y) commensurate with the current heating operation based on the actual conditions of the previous heating operation and defrosting operation, and using it as a factor in calculating the average heating capacity, accurate defrosting can be achieved. Can take frost timing.

Therefore, even when the outside temperature is low and dry, defrost will not be activated until the average value of the heating capacity reaches its maximum value and there is still room for heating capacity, so empty defrost will not occur. It can be prevented.

(Example) Embodiments of the present invention will be described below 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, including a compressor (5), a four-way switching valve (6), a heat source side coil (7), a capillary tube (8), and a user side The coil (9) and the accumulator α constitute a known refrigeration circuit, and during heating operation, the refrigerant is made to flow in the direction indicated by the solid line arrow, and the user side coil (9) is used as a condenser.

The heat source side coils (7) are respectively made to act on the evaporator, while
During cooling operation and defrosting operation, the refrigerant is made to flow in the direction indicated by the broken line arrow, so that the heat source side coil (7) acts on the condenser and the user side coil (9) acts on the evaporator, respectively. , Four-way switching valve (6) is used to change the flow direction of the refrigerant.
Needless to say, this can be done by switching the
In the case of defrost operation, both the heat source side fan Q31 and the usage side fan 00 are stopped.

In Fig. 2, aυ indicates the first temperature detector that detects the air temperature at the outlet of the utilization side coil (9), and a indicates the second temperature detector that also detects the air temperature at the inlet. The detectors 0υ and a2 constitute input elements of the cumulative heating capacity calculation means (1).

On the other hand, the αS de-Isa detects the coil inlet temperature of the heat source side coil (7) that serves as the evaporator during heating operation and checks whether it is below -5°C or not, and the built-in timer measures the heating operation time and checks whether it is 2. This defrost detector is a known defrost detector which generates a defrost required signal depending on whether or not a certain amount of time has elapsed, and is connected to the input end of the defrost command means.

The electronic control circuit that controls the defrosting of the air conditioner configured as described above is as shown schematically in FIG.
and ROM ell as basic elements.

A program to control the CPU C1η is written in the ROM (19), and the CPU aη takes in external data from the input port (2m) according to this program.
Alternatively, it performs arithmetic processing while exchanging data with the RAM α, and outputs the processed data to the output port (21) as necessary.

The output port (21) receives an output port designation signal from the CPU Q7), temporarily stores data in that port, and sends an analog signal via the D/A converter (25) to the solenoid of the four-way switching valve (6). (6,) and the motor (14M) of the user side fan αa.

On the other hand, when the input port (2Iil) receives the input boat designation signal from the CPUαη, it takes in the necessary information to that port, and the air outlet temperature (To) in the user-side coil (9) during heating operation is A. /D converter (22) as a digital signal, the air inlet temperature (Ti) passes through the A/D converter (23) as a digital signal, and the coil inlet of the heat source side coil (7) detected by the de-icer a. The temperature is output as a digital signal to each input port (21) via an A/D converter (24).

Therefore, the program control in this microcomputer 0[9 is performed by the integrated heating capacity calculation means (1), the predicted defrosting time calculation means (2), the average heating capacity calculation means (3),
FIG. 4 shows a flowchart of the program written in the ROM Ql, which is related to the configuration of the comparison means (4) and the defrosting command means.

Here, the theoretical basis for properly timing the defrosting start time in the present invention will be explained with reference to the diagrams from FIG. 7 onwards. Average heating capacity in (9),
In other words, it has a large effect on the average heating capacity of the air conditioner, and in order to improve EER, the average heating capacity, that is, the average value of the heating capacity from the start of heating operation to the start of the next heating operation, is important. The conditions for the maximum value must be satisfied, and the average heating capacity (Qn) when the user-side fan 0ω is stopped during defrosting in an air heat source, air-utilizing type air conditioner is given by the following formula.

However, △T,,: Average temperature difference ('C) th: Heating operation time (H,) C2: Specific heat of air (Kcal/kg・℃) r: Specific weight of air (kg/ rrr) &4: Air volume (rd/, H,
”) Ql: Average heating capacity (Kcaj2/H,) t4: Defrost operation time (Hl) In the above formula (a), since Cp l r +- is almost constant, Q7 is (△T, jh+ta) It can be seen as a function.

By the way, when heating operation and defrost operation are repeated alternately, the heating capacity, that is, the utilization side coil (9)
The value is proportional to the temperature difference (△T), which is the difference between the air outlet temperature (To) and the air inlet temperature (Ti') during heating, but the state in which this changes over time is the seventh
As shown in the figure, the transition of the temperature difference (ΔT) is at the start of heating operation (T.

) is zero, and the difference increases with operation, and when it reaches the maximum temperature value (△T, ), the capacity decreases due to the adhesion and growth of frost on the next heat source side coil (7). The temperature of the refrigerant (ΔT) gradually decreases to a state close to saturation.

Therefore, from each temperature difference (△T) read every predetermined time from the start of heating operation, for example every 30 seconds or every 1 minute, the integral value from the start of operation to the present time, that is, the heating capacity equivalent value The heating capacity value (
After calculating S) sequentially and obtaining the results shown in the diagram in Figure 8 as the first step, this heating capacity value (S) is calculated based on the current value after the previous defrosting operation was completed. Sequentially calculate the average heating capacity (Q) divided by the sum of the heating operation time (tr) performed so far and the predicted defrosting time (tdy) required for defrosting when the current heating is switched to defrosting. The calculated results shown in the diagram in FIG. 9 are obtained as the second step.

By the way, as is clear from each of the above graphs, the state of change in heating capacity value (S) from the start of heating operation to the maximum temperature difference (△T), that is, until reaching the maximum heating capacity value, is at a low level and steep. After reaching the maximum heating capacity value, the period when the capacity decreases is a gentle curve at a high level, and at a point where the heating capacity value is low due to frost formation and reaches a saturated state, it becomes a slightly steep curve at a high level. It becomes a curve.

Therefore, as shown in FIG. 9, the average heating capacity (b) reaches its maximum just before frost formation occurs and defrosting operation is required, and then decreases.

As is clear from the above points, if defrosting is performed by determining the time when the average heating capacity (b) calculated in a certain period of time is at its maximum, the EER can be maintained at its maximum and heating operation and defrosting operation can be performed. In short, when calculating the periodic average heating capacity (b), in order to find the conditions that maximize the value, it is necessary to find the condition that the current calculated value is smaller than the previous calculated value. This means that it is sufficient to judge.

By the way, in order to find the appropriate timing to stop the current heating operation and switch to defrosting operation, it is necessary to correctly predict the defrosting time that will occur after the current time, and then calculate the average heating capacity. However, the following can be said about the prediction of the defrosting operation time.

The heating operation time from the end of the previous defrosting operation to the current defrosting operation is tf, and the operating time of the current defrosting operation is t4.
Then, from Figure 10, the correlation between td and tr is td
=r;'(tr)''.

FIG. 10 is based on actual measurement data obtained by measuring the defrosting time (t4) in a laboratory while changing the operating time (tr) while keeping the outside temperature constant.

In the same figure, considering the minute interval, the first-order interval number t4=F(t
r), so based on this, if we switch to defrosting now, we can predict the appropriate defrosting time as follows.

The estimated defrosting operation time (time required for complete defrosting) is tdy.
, the previous heating operation time tu, the previous defrosting time td
, if the current heating operation time is t, then t, +=F(t
r), it is expressed as t, =a − tu +b.

; + 3 = tu 2'' 2, tu tay = ('dan - unicosy) ・ t, +b
... (b) The formula for tu is obtained.

Therefore, when two cycles of continuous operation are performed as shown below, both a and b can be determined and the predicted defrosting operation time (tay) can be obtained, assuming that the outside air conditions do not change.

t□=atu1+b... 1st previous time-td2=at
uz+b... 2 times before t□-t4□-a(t□-
tuz) jul L+4 tdl tdt Also, b=t□−atu+, and tdy can be found from this.

Based on the above considerations, to give an example of a case where it is used in a practical machine, when calculating a and b from the results of two-cycle operation,
There is a problem with whether the correlation between the two defrosts is correct (changes in outside air conditions, etc.), and that the value of a may be negative. Even if the refrigeration cycle is very close, it takes time to switch the refrigeration cycle, and there is a time lag determined by the heat capacity of the coil acting as an evaporator and condenser.
Generally speaking, it is reasonable to fix b = 1 assuming that it takes about 1 minute, and then from the operation result of 1 cycle, based on formula (0), L4y = ' and -uni' - 1... (
c) The predicted defrosting operation time (tdy) is determined from tu.

A flowchart for performing the defrosting operation based on the contents explained above will be explained with reference to FIGS. 4 to 6.

Turn on the heating operation switch to start heating the air conditioner (step ■), and perform initial settings (step ■).

This initial set is the heating operation time (tr) of the electronic timer.
) is reset to zero, which is the starting point, and the cumulative heating capacity value (S)
and average heating capacity (b) are set to zero, and further,
Since defrost operation has never been performed at the start of operation, one of the conditions for determining the subsequent timing is to set an appropriate defrost time (t4) such as 5 minutes, and to set a flag (FAg). ) to O and store them in the microcomputer αB.

In this way, the electronic timer starts measuring time and the heating operation time (t
r ) until it reaches 20 minutes, and then enter the measurement flow (step ■) shown in FIG. 5.

That is, first check that the heating operation is in progress (step ■), and then check the air outlet temperature (To) and air inlet temperature (Ti) every time a certain period of time (e.g., 1 minute) is counted (step @l). Calculate and store the temperature difference (△T,) (
Step ■).

In addition, since the operating mode is unstable (uncertain factors exist) until about 20 minutes have passed from the start of operation, the defrosting operation is not started in step (3) during this period.

While calculating the temperature difference (△Tfi) every minute, at the same time, this temperature difference value (△T,) is integrated to obtain the integrated heating capacity (S, ), and the flag (F
lg) is O (step @), so the next step [
phase] to calculate the average heating capacity (Qfi).

In this case, the average heating capacity (Qi) is the cumulative heating capacity (S, 1 ) is obtained by dividing.

Note that step 0.0 corresponds to the processing function of the cumulative heating capacity calculation means (1).

In this way, the heating operation continues and the operating time value is checked to be more than 20 minutes and less than 120 minutes (step
) Then, the average heating capacity value calculated this time (Qn) is compared in magnitude with the previous value (Qn-I) every minute during that time (step 2).

If the comparison result is Qn≧Qn−1, the measurement flow (step ■) is reached, and on the other hand, if n<Qr+−1
Since this means that the average heating capacity value (Qn) has passed the maximum value at that point and is in a state of decreasing, the comparison means (4) outputs a defrosting signal.

Note that step ■ is the processing of comparison means (4)! Corresponds to fl.

In this state, if the coil temperature of the heat source side coil (7) is 15°C or higher and the de-icer Q5) is not emitting a defrost signal (step ■), the measurement flow (step ■) is continued; If the defrost signal is being issued, the system will shift to the defrost flow (step ■).

This defrost flow is as shown in FIG.
) and reset the defrost operation time (t4) to zero (step ■),
Measure the vehicle position for 1 minute of defrost operation time (step 0).

As a result of entering the defrosting operation in the cooling cycle and melting the frost, when the de-icer αω detects that the coil temperature is 15° C. or more after the completion of defrosting and issues a defrosting release signal (step 0), After switching the cooling cycle to the heating cycle and moving to step [phase] to calculate (ta − t)/tu=a in the above equation (c), the heating operation time (1f) is set to zero and the cumulative heating A cycle end set is performed in which the capacity value (general) and the average heating capacity value (On) are reset to zero, and the flag (F 1 g) is set to 1 (step ■).

In step (2), if it is checked that two hours have passed since the start of the heating operation, and if it is also checked that a frost detection signal is being emitted from the de-icer α, the microcomputer 00 (in <Qll- This is a check function that forces defrosting operation to start even if the calculation result of step 1 is not obtained.

In this way, one cycle consisting of heating operation and defrosting operation is completed, and the operation from step ① is performed again.
The measurement flow (step ■) from the second cycle is as follows:
In FIG. 5, the flag in step ◎ is 1, so the process moves to the sequential operation in the right half.

First, in step (2), the equation (c) is calculated to calculate the predicted defrosting operation time (1, ty) when heating operation is switched to defrosting operation at the current time.

This step [phase] is naturally the predicted defrosting time calculation means (2)
This corresponds to the processing function of

The above calculation result may be carried directly into the calculation of step [phase], but for safety reasons, it is checked in step [phase] to step 0 and compared with the time (td) required for the previous defrosting. It is a preferable means to define the upper and lower limits so that the predicted defrosting operation time (Ctdy) falls within the range of 0.5 t, +≦td, ≦1.5 ta.

When the calculation of the predicted defrosting operation time (tuty) is completed in this way, the process proceeds to step [phase] of the processing procedure by the average heating capacity calculation means (3).

That is, the average heating capacity (Q9) is calculated by dividing the current cumulative heating capacity value (S, ) by the sum of the current cumulative heating operation time (tu) and the predicted defrosting operation time (tdy).
is calculated.

This calculation procedure is compared with Q, <Q in comparison means (4).

It is the same as in the case of the first cycle that the process is continued until the check of -1 is made and the defrosting operation is switched.

In this way, the point at which the average heating capacity (Qn) reaches its maximum is checked and the defrosting operation is performed, so the EER
It is possible to perform heating and defrosting operations alternately under the best conditions.

The example explained above is for a device that uses air as an air heat source and is generally referred to as an air-cooled air conditioner, and is constructed based on the assumption that there will be no negative effect on heating capacity by stopping the indoor fan during defrost operation. On the other hand, in the case of an air heat source/water utilization system called an air-cooled chiller, the negative capacity for heating capacity must be taken into consideration due to hot water being cooled during defrost operation. .

In that case, assuming that the temperature of the hot water decreases by about 5° C., the heating capacity corresponding to this temperature decrease is subtracted, and the other calculations are the same as in the above example.

(Effects of the Invention) As explained above, the present invention calculates a state in which the average heating capacity reaches its maximum value in response to a phenomenon in which the heating capacity decreases 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 early even when heating capacity is available, or delay defrosting even when capacity is reduced, and it takes into account surrounding conditions. Based on this, it is possible to set the optimal defrosting timing, and thus, it is possible to perform appropriate defrosting while maximizing the EER (Energy Effective Ratio) during heating operation.

Furthermore, when calculating the average heating capacity, the present invention uses the accurate prediction of the time of the next defrosting operation as the basis for calculation, so when calculating the average heating capacity, the mode of the previous defrosting operation is taken into account. Compared to this, it is not greatly affected by the past operation progress, and if the previous defrosting time is long, the next defrosting operation start time will be postponed, or vice versa, it will be shortened. This makes it possible to take appropriate defrosting timing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the 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 defrosting control, and FIGS. 4 to 6 are A 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 FIG. 10 shows defrosting time and changes in heating operating time with respect to changes. It is a diagram showing changes in the amount of frost formation. (1)...Cumulative heating capacity calculation means, (2)...Predicted defrosting time calculation means, (3)...Average heating capacity calculation means, (4)...Comparison means, (9).・Using side coil. Figure 1 Figure 4 Figure 5 Figure 6 Figure 7 vtrya<min) Figure 9 Figure 10

Claims (1)

[Claims] 1. Cumulative heating capacity calculation means (1) that periodically calculates and stores the cumulative heating capacity (S_n) from the start of heating operation immediately after the end of defrosting in the user-side coil (9) during heating operation at fixed time intervals; The previous defrosting operation is completed based on the relationship between the cumulative heating operation time (t_u) from the end of the previous defrosting operation to the start of the previous defrosting operation and the previous defrosting operation time (t_d). Heating operation time (t_f) that has been carried out since then until now
a predicted defrosting time calculation means (2) that linearly calculates a predicted defrosting operation time (t_d_y) for the heating; an average heating capacity calculation means (3) that calculates and stores an average heating capacity (Q_n) by dividing by the sum of the operating time (t_f) and the predicted defrosting operation time (t_d_y); Comparison means for comparing the current value (Q_n) and the previous value (Q_n_-_1) of the average heating capacity (Q_n) calculated by the means (3) and outputting a defrosting signal when the current value is small. (4) A defrosting device for an air conditioner, comprising: