JPH0765841B2 - Defrost control device for refrigeration equipment - Google Patents

Description

The present invention relates to a defrost control device for a refrigeration system having a defrost execution timer.

[Conventional technology]

Is the conventional defrost execution timer fixed at a fixed time?
Alternatively, it has a defrosting interval switch so that a desired interval can be selected.

For example, FIG. 5 is a diagram showing the configuration of a refrigeration system having a conventional defrost control device.

In the conventional device shown in FIG. 5, the defrosting control device 8'is designed to start defrosting periodically with a built-in timer having a fixed time or a timer time selected by the changeover switch 30.

In FIG. 5, 1 is a compressor, 2 is a condenser, 3 is a throttle, 4 is an evaporator, 5'is a temperature control device, 6 is an inside air temperature sensor, 7 is a temperature setter, and 8'is. Defrost control device, 9
Is a defrosting completion temperature sensor, 10 is a defrosting heater, and 30 is a changeover switch.

[Problems to be Solved by the Invention]

As described above, in the conventional device, the defrosting execution interval is carried out at regular intervals regardless of the frosting condition of the evaporator, so the defrosting execution interval is too long and a large amount of frost is formed on the evaporator. However, defrosting is not performed, the ventilation of the evaporator is obstructed, the refrigeration capacity is reduced, the temperature inside the freezer cannot be maintained at the set temperature, the control temperature rises, and the refrigerant evaporates in the evaporator. Since the refrigerant became liquid and returned to the compressor as a result of liquid compression, the compressor might be damaged. On the other hand, the defrosting interval is too short to frost the evaporator, and defrosting is performed while the evaporator's refrigerating capacity can be fully exerted. Then, the electric power required for lowering the temperature inside the evaporator and the freezer by the refrigerating operation is wasted again.

Further, even when the desired interval can be selected, since the optimum defrosting interval cannot be predicted, in order to eliminate the above-mentioned inconvenience, the defrosting condition is carefully observed and the length of the defrosting interval is appropriately determined, It was complicated because the defrosting execution interval had to be changed.

An object of the present invention is to provide a defrost control device for a refrigeration system that can solve the above-mentioned conventional problems.

[Means for Solving the Problems]

In the present invention, when the amount of frost on the evaporator is large, the defrost required time is long, and conversely, when the amount of frost on the evaporator is small, the defrost required time is shortened, and the defrost The defrosting interval is automatically changed according to the required time, and when the same defrosting interval is repeated a predetermined number of times, the defrosting interval is lengthened depending on the defrosting time required at that time, and the refrigeration capacity due to frost formation When the control temperature rises due to the decrease, a defrost control device having a means for correcting the defrosting execution interval short is provided.

A defrosting control device for a refrigerating apparatus according to the present invention constitutes a refrigerating cycle by a compressor, a condenser, a throttle mechanism, and an evaporator, and a defrosting heater is provided on the evaporator, and the heater is provided with a defrosting execution interval. In a defrosting control device for a refrigerating device that performs defrosting by energizing each time, a timekeeping means for timing each defrosting required time for each defrosting execution interval, and a means for counting the number of defrosting times in the same interval, When the defrosting required time clocked by the timekeeping means is a predetermined time or more, the defrosting execution interval is shortened, and when the defrosting required time is within a predetermined time, the difference is compared with the previous defrosting required time. When it is larger than a predetermined value, the defrosting execution interval is lengthened, and when the difference from the previous defrosting required time is smaller than a predetermined value, the count value of the number of times of defrosting makes the same interval. Defrosting interval determining means for determining whether or not defrosting has been performed a predetermined number of times, and extending the defrosting interval when the defrosting has been performed a predetermined number of times, and performing defrosting based on the interval determined by the determining means And a defrosting control means for controlling the defrosting.

[Action]

According to the present invention, the defrosting execution interval is automatically changed depending on the defrosting required time, that is, the amount of frost on the evaporator and whether or not the control temperature rises. It is possible to eliminate the trouble of defrosting, raising the control temperature due to frost formation, backing the liquid to the compressor, and selecting the defrosting execution interval.

〔Example〕

FIG. 1 is a diagram showing the configuration of a refrigerating apparatus having a delayering control apparatus according to an embodiment of the present invention.

In FIG. 1, the high-temperature and high-pressure refrigerant gas compressed by the compressor 1 is cooled by the condenser 2 and condensed and liquefied. Then, the pressure is reduced by the throttle 3, the evaporator 4 exchanges heat with the air in the freezer, evaporates, and returns to the compressor 1. The temperature control device 5 turns on and off the compressor 1 so that the inside air temperature sensor 6
The in-compartment air temperature detected by is maintained at the temperature set by the temperature setting device 7. The defrost control device 8 determines a defrosting execution interval, turns on the defrosting heater 10 at each of the determined intervals, and the temperature detected by the defrosting completion temperature sensor 9 installed in the evaporator 4 rises to a predetermined value. When this is done, defrosting is completed and the defrosting heater 10 is turned off. During defrosting, the temperature control device 5 receives the signal from the defrosting control device 8 and turns off the compressor 1 to stop the cooling operation.

FIG. 2 is a diagram showing the relationship between the amount of frost on the evaporator 4, the time required for defrosting, and the temperature inside the refrigerator. The time required for defrosting increases as the amount of frost formed increases because more heat is required for frost melting. Further, as the temperature inside the refrigerator becomes lower, more heat is required to raise the temperature of the evaporator 4 and the frost that has formed frost, so the time required for defrosting becomes longer. Even if the amount of frost is 0, the defrosting required time does not become 0 because the temperature of the evaporator 4 rises, and the defrosting required time becomes larger as the inside temperature lowers. If the amount of frost is larger than the point A, the refrigerating capacity is lowered and the temperature inside the refrigerator cannot be maintained. If the amount of frost is smaller than the point B, the refrigerating capacity is sufficiently large. It will be useless defrosting. Therefore, a multi-stage defrosting execution interval is provided, and the defrosting execution interval is sequentially lengthened by shortening the time required for defrosting each time. That is, when the difference Δt between the previous defrosting required time and the current defrosting required time becomes greater than a predetermined value, it is considered that the frost formation amount during the defrosting execution interval from the previous time to this time is small, and the next defrosting time is determined. The time to frost, that is, the defrosting interval is 1
Lengthen the stage. The predetermined value of Δt is a value determined in advance by a test for the time required to melt the increased amount of frost formation corresponding to the longer defrosting execution interval. When the time required for defrosting for each time gradually decreases and Δt does not become larger than the predetermined value, the defrosting execution interval cannot be lengthened, and the same defrosting interval is repeated. In order to avoid this, when the same interval is repeated a predetermined number of times n times and the time is less than the defrosting required time t ₁ or t ₂ according to the temperature inside the warehouse, the defrosting execution interval is lengthened by one step. The predetermined number of times n may be 1, but it is preferable that the predetermined number of times n be set to a plurality of times in consideration of the margin until the amount of water generated in the freezer decreases. In addition, by increasing the defrosting interval, the defrosting required time depends on the temperature inside the chamber.
When it becomes larger than t ₃ and t ₄ , the next defrosting execution interval is shortened by one step. Further, during each defrosting execution interval, the generation of water in the refrigerator suddenly increases for some reason, so that the amount of frost on the evaporator 4 increases, the refrigerating capacity decreases, and the control temperature rises. Just in case
It is also possible to add the following function of the above characteristics. That is, after the control temperature once reaches the set temperature, if the control temperature rises above the set temperature by a predetermined temperature or more even though the compressor is operating, immediate defrosting is performed and the defrosting execution interval is set to 1 Keep the steps short.

FIG. 3 is a functional block diagram of an embodiment of the present invention.

In FIG. 3, the temperature control means 14 is a control temperature setting means 7.
The air temperature detected by the in-compartment air temperature sensor 6 is maintained based on the set temperature set by. Therefore, the compressor driving means 21 turns on and off the compressor 1.

The defrost control means 15 instructs the heater driving means 22 by the time-up signal of the timer means 18, turns on the heater 10, and defrosts. The heater driving means 22 is instructed by the signal of the defrosting completion temperature sensor 9 to turn off the heater 10. Further, when defrosting is started, a defrosting start signal is sent to the temperature control means 14, whereby the temperature control means 14 interrupts the temperature control, and if the compressor is operating, the compressor driving means 21 turns off the compressor 1.
When the defrosting is completed, a defrosting completion signal is sent to the temperature control means 14, and the temperature control means 14 restarts the temperature control.

The defrosting required time counting means 16 counts by the timer means 17 in response to the defrosting start and completion signals from the defrosting control means 15 and measures the defrosting required time each time, and the counting result is the defrosting execution interval determining means. Tell 19.

The defrosting interval determination means 19 transmits the determined defrosting interval to the defrosting control means 15, whereby the defrosting control means 15 sets the time of the timer means 18. The defrosting frequency counting means 20 is incremented by the defrosting execution interval determining means 19 in response to the start signal of the defrosting control means 15 during the same defrosting interval, and the defrosting execution interval is changed. Is reset to zero. As described above, the defrosting execution interval is determined by comparing the results of the defrosting time measuring means 16, the count value of the defrosting number counting means 20, the control temperature from the temperature control means 14, and the compressor operation signal.

FIG. 4 is a flow of determining the defrosting execution interval in the embodiment of the present invention.

In FIG. 4, when the defrosting is started, the defrosting required time counting timer is reset and the counting is started. When defrosting is completed,
The current defrosting required time Tn (defrosting required time counting timer value) is stored. When Tn is longer than the predetermined time, or when the defrosting this time is defrosting due to the rise in the control temperature once the set temperature is reached, the defrosting execution interval is made one step shorter than the current interval. Reset the defrosting counter to zero. When Tn is within the predetermined time, it is compared whether the difference ΔT = Tn ₋₁ −Tn from the previous defrosting required time Tn ₋₁ is larger than the predetermined value. As a result, when ΔT is larger than the predetermined value, the defrosting execution interval is made one step longer than the current interval, and the defrosting frequency counter is reset to zero. When ΔT is less than or equal to a predetermined value, it is compared whether the defrosting frequency counter is greater than a predetermined value. When Tn is less than a predetermined time, the defrosting execution interval is made one step longer than the current interval. At the same time, the defrosting frequency count is reset to zero, and if Tn is equal to or longer than the predetermined time, the defrosting execution interval is kept as it is and the defrosting frequency counter is counted up. When Δt is equal to or less than the predetermined value and the defrosting frequency counter is smaller than the predetermined value, the defrosting execution interval is kept as it is and the defrosting frequency counter is counted up.

〔The invention's effect〕

According to the present invention, since the defrosting execution interval is automatically selected as an appropriate value, useless power consumption required for defrosting,
It is possible to eliminate the increase in the control temperature due to frost formation, the liquid back to the compressor, the time and effort required for determining the selection of the defrosting execution interval, and the erroneous setting when setting the defrosting interval.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigerating apparatus according to an embodiment of the present invention,
FIG. 2 is a diagram showing the relationship between the amount of frost formation, the time required for defrosting, and the temperature inside the refrigerator, and FIG. 3 is a functional block diagram of one embodiment of the present invention.
FIG. 4 is a flow chart for determining a defrosting execution interval according to an embodiment of the present invention, and FIG. 5 is a diagram showing a configuration of a conventional refrigeration system. 5 ... Temperature control device, 8 ... Defrost control device, 14 ... Temperature control means, 15 ... Defrost control means, 16 ... Defrost required time counting means, 17, 18 ... Timer means, 19 ... … Defrosting interval determination means, 20 …… Defrosting frequency counting means, 21 ……
Compressor drive means, 22 ... Heater drive means.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Isomichi Kanzou, Takadō No.1, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi Mitsubishi Heavy Industries, Ltd. Nagoya Research Institute (72) Hiroshi Ogawa Iwatsuka, Nakamura-ku, Nagoya, Aichi Machiji Takamichi No. 1 Mitsubishi Heavy Industries, Ltd. Nagoya Research Institute (56) Reference JP 62-206370 (JP, A) JP 62-134475 (JP, A)

Claims (1)

[Claims] 1. A compressor, a condenser, a throttle mechanism, and an evaporator constitute a refrigeration cycle, and a heater for defrosting is provided on the evaporator, and the heater is energized at every defrosting interval to defrost. In the defrosting control device of the refrigerating device for performing, the time counting means for counting each defrosting required time for each defrosting execution interval, the means for counting the number of defrosting times in the same interval, and the time counting means When the defrosting required time is a predetermined time or more, the defrosting execution interval is shortened, and when the defrosting required time is within a predetermined time, compared with the previous defrosting required time, when the difference is larger than a predetermined value, defrosting is performed. When the implementation interval is lengthened and the difference from the previous defrosting required time is smaller than a predetermined value, defrosting at the same interval was performed a predetermined number of times by the count value of the defrosting frequency. Defrosting execution interval determining means for determining whether or not the defrosting execution interval is lengthened when a predetermined number of times has been performed, and defrosting control means for performing defrosting based on the interval determined by the determining means. A defrosting control device for a refrigeration system, comprising: