JPS58158476A - Controller for defrostation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a defrosting control device for a refrigerator-freezer or the like.

In general, in various types of cooling devices such as refrigerators, frost adhering to the surface of the cooler is one of the main causes of lowering the cooling capacity, and defrosting measures are important.

Conventionally, most defrosting devices use a timer to accumulate the operating time of the compressor and start defrosting when the accumulated time reaches a predetermined time. For seed crops, defrosting is performed regardless of the amount of frost, which is not desirable from an energy saving perspective.

On the other hand, if a frost sensor is used to detect the amount of frost and defrost is performed according to the amount of frost, wasteful defrosting can be avoided and efficient defrosting can be expected. The distribution of frost on the ground is not uniform and varies considerably depending on environmental conditions. In addition, the cooling capacity decreases only after a significant amount of frost has formed, and the frost condition becomes unstable, making it extremely difficult to detect this with a frost sensor. .

The present invention was invented in view of the above-mentioned matters.

The objective is to provide a highly reliable defrost control device with an easy-to-design frost sensor.

FIG. 1 is a block diagram of the device of the present invention, in which a microprocessor 1 is used for control, and a timer function can be easily implemented using software. Reference numeral 6 denotes a frost sensor for detecting frost formation. For example, it is an optical transmission type frost sensor having characteristics as shown in the curve (a) in Figure 2. It detects the state.

7 is a conventionally used temperature sensor for detecting the end of defrosting, which senses when the frost melts and the temperature around the cooler rises due to the operation of the defrosting circuit (not shown). This is to stop the defrosting circuit. 8 is a relay for switching between cooling operation and defrosting operation, and output port 4
Through the microprocessor 1, either the cooling operation or the defrosting operation can be switched.

Note that 5 is a comparator and 2 is a memory.

Assume now that the frost amount M in FIG. 2 is the optimum value for starting defrosting.

In this case, it is sufficient to determine whether to start defrosting by using the output vM of the frost sensor as a reference level. However, as can be seen from the characteristics shown in FIG. 2, when the amount of frost buildup exceeds a certain level, the output change of the frost sensor becomes small, and it is difficult to design a frost sensor with a large output change in this range. The state of frost formation is still unstable, which causes a large variation in detection.

Therefore, if we set the reference level eVt of the frost sensor output and start defrosting after a predetermined delay time △T as shown in Figure 3, we will detect almost the same amount of frost as when we set vM as the reference level. It will be possible.

This simplifies the design of the frost sensor and also allows the reference level to be set at a location where the output of the frost sensor has a large change, making it possible to reliably detect frost formation.

The above operations can be easily realized under the control of the microprocessor shown in FIG.

That is, during cooling operation, the output of the frost sensor 6 is at the reference level V.
The comparator 5 compares whether the value is less than 1, and the microprocessor 1 checks through the input port 3.

If the frost sensor output becomes less than v1, microprocessor 1
After the delay means within is activated and a predetermined time ΔT has elapsed, the relay 8 is switched to the defrosting operation side through the output port 4. In this case, the microprocessor 1 integrates only the operating time △T' (constant) of the compressor, and allows △T (=ΔT'+△T'') to change according to the non-operating time △f. desirable. In some cases, it is also possible to determine ΔT in accordance with the time T from the start of the cooling operation until the output of the frost sensor 6 reaches the reference level Vl. (That is, ΔD = αT) Furthermore, fine-grained control such as changing the value of α according to the value of T can be easily realized using the microprocessor-1.

In the above embodiment, an optical transmissive type frost sensor 6 is used, but it is of course applicable to a completely different type of frost sensor.

As described above, the present invention provides a defrosting control device that detects frost formation using a frost sensor and performs defrosting. Since the frost sensor is equipped with a delay means for driving the frost sensor, it is easy to design the frost sensor, and since frost formation is detected reliably, highly reliable defrosting control can be performed, which is a remarkable effect. It is something.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of the device of the present invention, FIG. 2 is a diagram showing the output characteristics of the frost sensor used in the device of the present invention, and FIG. 3 is a characteristic diagram of the temporal change of the frost sensor in the device of the present invention. Microprocessor, 6: [Sensor. Agent Patent attorney Aihiko Fuku (and 2 others) Sun
O coin limit and pigeon 4A mold

Claims (1)

[Claims] 1. In a defrosting control device that detects frost formation using a frost sensor and performs defrosting, a delay means that drives a defrosting circuit after a predetermined delay time after the output of the frost sensor reaches a reference level. A defrosting control device characterized by being equipped with.