JPH033149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a defrosting control device that determines the frosting state of an air cooler used in a refrigeration system and controls the start of defrosting and the defrosting time.

Conventionally, there has been a device of this type as shown in FIG. In the figure, 1 is the voltage detector of the blower of the air cooler for the refrigeration system (not shown), 2 is the current detector of the blower, 3 is the internal temperature detector, 4 is the expansion valve liquid outlet temperature detector, 5 is a temperature sensor at the gas outlet of the air cooler, 6 is a temperature difference α ₀ setting device for setting the temperature difference α ₀ °C between the internal temperature and the expansion valve liquid outlet temperature, and 7 is a blower in a frosted state. a blower current ratio K _{0 setting device that determines the blower current ratio K 0 %} , _which is the ratio between the current I and the blower current I 0 in a non-frosted state after defrosting;
Reference numeral 8 denotes a computing unit that takes in the output signals from these detectors 1 to 5 and setters 6 to 8 and performs calculations for defrosting control, and 9 indicates a defrosting heat source unit (not shown) from this computing unit 8. an output section for outputting an output signal to 10;
1 is a storage unit that stores programs and data for defrosting control in the defrosting calculator 8, and 11 is a manual defrosting input unit that includes input keys.

Next, the operation will be explained.

If the refrigeration operation continues, frost buildup on the air cooler (not shown) progresses, and as a result, the cooling capacity decreases, so defrosting must be performed from time to time. In the conventional method, the set values α _{0 and} K 0 input from the temperature difference α ₀ setting device 6 and the blower current ratio K ₀ setting device ₇ , and the voltage detector 1, current detector 2, and internal temperature due to frost formation Temperature difference α that changes from moment to moment obtained from the detection signals detected by the detector 3 and the expansion valve liquid outlet temperature sensor 4
and the blower current ratio K are compared in the calculator 8, and α
When and K match their respective set values α ₀ and K ₀ ,
A defrosting start command is output from the output unit 9.

Further, when defrosting progresses and the temperature value input from the air cooler outlet gas temperature detector 5 rises above a specified value, a defrosting end command is output from the calculator 8 to the output section 9.

In this case, it is also possible to output the defrosting command output to the output section 9 using a signal from the manual defrosting input section 11.

In conventional defrosting control devices, the set temperature for starting defrosting, the difference α ₀ and the blower current ratio K ₀ are manually set, so these set values α ₀ , K ₀
Settings often rely on experience and testing, and these settings vary depending on the field, so
There were problems in that it took a lot of time to find the optimal setting values and the detection accuracy was low.

This invention was made to eliminate the above-mentioned conventional problems.The temperature difference α ₀ , blower current ratio K ₀ , defrosting time, etc. are set as initial values, and when the refrigerator is operating, Calculate the temperature difference α between the internal temperature and the evaporation temperature and the ratio K between the blower current and the reference blower current, and calculate this temperature difference α and the current ratio K.
exceeds the set value α ₀ , K ₀ When at least one of K exceeds the set value α ₀ , K ₀ , a defrost start command is sent, and the defrost time and defrost end temperature of the cooler are When reaches the set value, sends a defrosting end command, and further maintains the set values α ₀ and K ₀ when the time required for defrosting is within the allowable time range,
By configuring the system to automatically change the set values α ₀ and K ₀ to the optimal defrosting start time when the time is outside the allowable time range, the hassle and difficulty of setting the defrost start time is eliminated. However, it is an object of the present invention to provide a defrosting control device that is inexpensive and capable of highly accurate frost formation determination.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is an overall configuration diagram showing an example of a defrosting control device according to the present invention.

In the figure, the arithmetic control unit 13 that controls the start of defrosting and the defrosting time includes a cooler blower voltage detector 1, a blower current detector 2, an internal temperature detector 3, an expansion valve liquid outlet temperature (evaporation temperature ) The detector 4 and the gas outlet temperature sensor 5 of the cooler are connected, and the defrosting end time t ₀ , maximum defrosting time T _MAX , and minimum defrosting time are connected.
Input section 1 with keyboard configuration for inputting T _MIN , temperature difference α ₁ (initial value), blower current ratio K ₀ (initialization), etc.
1 and a memory key 12 for storing the initial setting values input through the input section 11 in the memory section 14.
is connected. The memory unit 14 includes a program for importing input data, a program for storing the temperature difference (initial value) α ₀ at the defrosting start point and the blower current ratio (initial value) K ₀ in the memory unit 14;
Program for calculating temperature difference α and current ratio K during cooling operation, α and K, and semi-set value α ₀ and
A comparison judgment program with K ₀ and a program for changing the set values α ₀ and K ₀ according to the defrosting time from the start of defrosting to the end of defrosting are stored, as well as calculation results of the calculation control unit 13 and various Input data is now stored.

Further, various output commands based on the determination results in the arithmetic control section 13 are sent to the output section 9.

Next, the operation of this embodiment configured as described above will be explained according to the flowchart shown in FIG.

When controlling the defrosting of the cooler, first, in step _S1 of FIG. The time T _MAX and the minimum defrosting time T _MIN are input, and the input data is stored in the memory section 14 by operating the memory key 12 .

Next, in step S2, by operating the keys on the input unit 11, the temperature difference α ₀ between the internal temperature at the defrosting start point and the evaporation temperature is input as an initial setting value, and this is input by operating the memory key 12. In the memory section 14
to be memorized. Furthermore, in the next step S3,
The ratio K ₀ between the blower current at the defrosting start point and the blower current when no frost is formed is input by operating the keys on the input unit 11 as an initial setting value, and this is stored in the memory unit 14 by operating the memory key 12 .

With the initial values set as described above, the refrigerator is operated for cooling (step S4). When the refrigerator operates for cooling, frost begins to form on its air cooler (not shown). In the next step S5,
The internal temperature detected by the internal temperature detector 3 and the evaporation temperature detected by the expansion valve liquid outlet temperature detector 4 are input into the arithmetic control section 13 to calculate the temperature difference α between the two. In the next step S6, a ratio K between the cooling fan current detected by the fan current detector 2 and the reference fan current is calculated. In step S7, it is determined whether the calculated temperature difference α and current ratio K exceed the initial set values α ₀ and K ₀ stored in the memory section 14. Here, α and K are set values (reference values) α ₀ ,
If K is less than ₀ , return to step S4, step S5,
The process shown in S6 is repeatedly executed until α-α ₀ ≧0 and K-K ₀ ≧0.

Also, in step S7, α−α ₀ ≧0, K
− If it is determined that K ₀ ≧ 0, the step
Proceeding to S8, it is determined which of α and K exceeds the reference value first. Here, K is first the reference value K ₀
If it is determined that the temperature exceeds the threshold value, the process proceeds to step S9, where the arithmetic and control section 13 issues a defrosting start command to the output section 9 to defrost the air cooler. Along with this,
In step S9a, the hot gas bypass solenoid valve is opened to allow hot gas to flow into the air cooler. Then, in the next step S9b, the main liquid solenoid valve is closed to stop feeding the condensed liquid. When defrosting of the air cooler is started in this way, in step S10, the temperature _tS of the air cooler is taken in from the temperature detector 5, and in the next step S11, it is compared with the defrosting end temperature _t0 , Determine whether t _S ≧t ₀ . Simultaneously with the start of defrosting of the air cooler, a timer (not shown) built in the arithmetic and control unit 13 starts operating and counts the defrosting start time T (step S12). The time T is compared with the maximum defrosting time T _MAX to determine whether T≧ _MAX . Then, if it is determined that t _S ≧t ₀ or T ≧T _MAX ,
Proceeding to step S13a, the hot gas bypass solenoid valve is closed to stop the supply of hot gas to the air cooler. After that, in step S14, the calculation control section 1
3, a defrosting end command is sent to the output section 9.

In the next step S15, the defrost time T is set and is within the maximum and minimum defrost times, that is, T _MAX > T >
Determine whether it is at T _MIN . Here, when it is determined that the defrosting time T is within the set time range,
Return to step S4. If it is determined that the defrosting time T is outside the set time, the process proceeds to step S16, where it is determined whether T>T _MAX or T<T _MIN .
Here, when it is determined that T>T _MAX , the step
Proceeding to S17, the reference value α ₀ is decreased by −Δα ₀ , and the initial reference value α ₀ stored in the memory unit 14 is reduced to α ₀ −Δα ₀ .
Rewrite it to . Also, in step S16, T
If it is determined that <T _MIN , proceed to step S18,
The reference value K ₀ is increased by +ΔK ₀ and the initial reference value K ₀ stored in the memory unit 14 is rewritten to K ₀ +ΔK ₀ .

On the other hand, if it is determined in step S8 that α has exceeded the reference value _α0 , the process proceeds to step S19, where the arithmetic and control unit 13 issues a defrosting start command to the output unit 9 to defrost the air cooler. I do. Accordingly, in step S19a, the hot gas bypass solenoid valve is opened to flow the hot gas to the air cooler. Then, in the next step S19b, the main liquid solenoid valve is closed to stop feeding the condensed liquid. When defrosting of the air cooler is started, in step S20, the temperature t _S of the air cooler is
is taken in from the temperature detector 5, and compared with the defrosting end temperature _t0 in the next step S21 to determine whether _tS ≧ _t0 .
Also, at the same time as the air cooler starts defrosting, a timer (not shown) built in the arithmetic and control unit 13 starts operating and counts the defrosting start time T (step
S22), and in step S23, the defrosting time T is compared with the maximum defrosting time _TMAX to determine whether T≧ _TMAX . and t _S ≧t ₀ or T ≧T _MAX
If it is determined that
Proceed to S21a and close the hot gas bypass solenoid valve to stop supplying hot gas to the air cooler. Thereafter, in step S24, a defrosting end command is sent from the arithmetic control section 13 to the output section 9.

Next, in step S25, the defrost time T is set and is within the maximum and minimum defrost times, that is, T _MAX > T >
Determine whether it is at T _MIN . Here, when it is determined that the defrosting time T is within the set time range, the process returns to step S4. If it is determined that the defrosting time T is outside the set time, the process proceeds to step S26, where it is determined whether T>T _MAX or T<T _MIN . Here, when it is determined that T>T _MAX , step S27
, the reference value K ₀ is decreased by −ΔK ₀ , and the initial reference value K ₀ stored in the memory unit 14 is reduced to K ₀ −ΔK ₀
Rewrite it to . Also, in step S26, T
If it is determined that <T _MIN , proceed to step S28,
The reference value α ₀ is increased by +Δα ₀ and the initial reference value α ₀ stored in the memory unit 14 is rewritten to α ₀ +Δα ₀ .

In this embodiment as described above, α and K calculated during the cooling operation are both the initial setting reference value α ₀ ,
When K ₀ is exceeded, defrosting is started, and if the time T required for defrosting is within the preset allowable time range (between T _MAX and T _MIN ), that is, the flow shown in Figure 3 is activated. The result of step S15 shown in the chart is
If YES, the defrosting start reference values α ₀ and K ₀ are not changed, and either α ₀ or K ₀ is changed when the value becomes T _MAX or more or T _MIN or less. Which one to change is determined depending on which of the above-mentioned α or K exceeds the reference value first, and the reference value Δα ₀ or ΔK ₀ is increased or decreased. If YES in steps S11 and S12 shown in the flowchart of Figure 3,
The defrosting time is T _MAX > T > T _MIN , and in this case, the defrosting time T is further determined in steps S15, S16, and S26, and whether it is within the allowable time range (T _MAX > T > T _MIN ). Determine. If it is determined that the time is outside the allowable time range, the reference values α ₀ and K ₀ that influence the defrosting start time are changed to Δα ₀ , K according to which of α and K exceeds the reference value first. Automatically increase or decrease by ₀ minutes. As a result, the defrost start time can be automatically set within the allowable time range, and compared to the conventional method of manually setting α ₀ and ΔK ₀ , the defrost start time can be set automatically. In addition to eliminating the hassle and difficulty of setting, it also enables highly reliable and low-cost defrost control.

In the defrosting example, when both the temperature difference α and the blower current ratio K exceed the set values,
Although the defrosting command is shown as being issued, the defrosting control may be performed using only one of the temperature difference α and the blower current ratio K.

In addition, in the defrosting embodiment, a case has been described in which the initial setting inputs of t ₀ , α ₀ , and K ₀ are input from the output unit 9, but the invention is not limited to this. For example, defrosting is necessary by checking the frosting state. When it is determined that defrosting has been completed, press the memory key 12 and receive the input from the voltage detector 1, current detector 2, chamber temperature detector 3, and expansion valve liquid outlet temperature detector 4. The value may be processed by the arithmetic control section 13 and stored in the memory section 14 as a set value.

As described above, according to the present invention, when it is determined that the time T required for defrosting is outside the preset allowable time range, the reference values α ₀ , K ₀ that influence the timing to start defrosting are determined. The system is configured to automatically change the defrost start time to the optimum time, eliminating the hassle and difficulty of setting the defrost start time, and also making it possible to determine frost formation at a low cost and with high precision. effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional defrosting control device, FIG. 2 is a block diagram showing an embodiment of the defrosting control device according to the present invention, and FIG. 3 is a flowchart for explaining the operation of this embodiment. It is. 1... Voltage detector, 2... Current detector, 3...
Internal temperature detector, 4... Expansion valve liquid outlet temperature detector, 5... Air cooler gas outlet temperature detector, 11
...Manual input section, 12...Memory key, 13...
Arithmetic control unit, 14...memory unit.

Claims (1)

[Claims] 1 The defrosting end temperature of the refrigerator cooler, the allowable defrosting time range, the temperature difference α ₀ between the internal temperature at the defrosting start point and the evaporation temperature, and the blower current at the start of defrosting and when no frost is formed. A means for inputting and storing the ratio K ₀ to the blower current, the temperature difference α between the internal temperature and the evaporation temperature when the refrigerator is operating, and the ratio K between the blower current at this time and the blower current when no frost is formed. A means of calculating,
When at least one of the temperature difference α and the current ratio K exceeds the set value α ₀ , K ₀ , a defrost start command is sent, and a reference value for the maximum defrost time is set.
T _MAX is the standard value of the minimum defrosting time, T _MIN is the standard value of the defrosting end temperature of the cooler, and _T is the elapsed defrosting time during defrosting, and temperature change of the evaporator during defrosting is When t _S is T ≧ T _MAX or t _S ≧ t ₀ , means for sending a defrosting end signal, and when the time required for defrosting is within the permissible time range, the set value α ₀ , K 1. A defrosting control device comprising means for automatically changing ₀ so that the defrosting time T satisfies T _MAX > T > T _MIN .