JPS61159071A - Defrostation controller - 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 (Technical Field of the Invention) The present invention relates to a defrosting control device for defrosting an evaporator of an air conditioner, a refrigerating showcase, or the like.

[Invention 9 Technical Background and Problems Therein] There is a conventional defrosting control device of this type that integrates the operating time of the refrigeration cycle and defrosts when the integrated time reaches a set value. However, when using this integrated time as a standard, the amount of frost changes depending on the load conditions, and when the load is light, defrosting is performed even if the amount of frost is small, increasing power consumption, but when the load is heavy, the amount of frost is increased. This method has the disadvantage that even if there is a large amount of frost, the cooling efficiency is reduced because the frost is not removed.

Therefore, an apparatus has been proposed that optically detects the amount of frost and performs defrosting based on the detection signal.

To detect the amount of frost, as shown in Figure 6, light is irradiated onto the surface of the evaporator 2, and the intensity of the reflected light changes depending on the amount of frost 3 attached to the irradiated surface. A reflective frost detection device 1 for detecting frost, or as shown in FIG. A transmission-type frost detection lAl4 is used that detects the intensity of transmitted light that changes depending on the amount of M3 attached to the hole.

As shown in FIG. 8, the frost i and IJ II devices using these frost detection devices are configured to output signals from the frost detection device 11 and the level setter 12 which sets the defrost start level and defrost return level. The output signal is compared with the output signal by the comparator 13, and when the amount of frost formation exceeds the set level, the defrosting device 14 switches the four-way valve, opens the hot gas bypass valve,
Alternatively, there were devices that turned on the power to the defrosting heater.

However, in the frost control device shown in Fig. 8, the frost detection device has a large error due to the frost density changing depending on the frost growth conditions, and it is difficult to properly remove the frost according to the frost amount. It was difficult to control frost.

On the other hand, if the level setter 12 is set to perform defrosting operation even if only a small amount of frost has adhered, taking into account the error of the frost detection device, there is a problem that defrosting operation is performed frequently and power is wasted. there were.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and aims to provide a defrosting control device that can perform reliable defrosting even when frost densities are different and can significantly reduce the number of times of defrosting.

[Summary of the invention]

In order to achieve this object, the present invention, as shown in the block diagram of FIG.
The level setting means 102 outputs a defrosting return signal and a defrosting end signal at a level corresponding to the amount i, and the outputs of this level setting means and the frost detecting means are compared, and the amount of frosting increases to the defrosting start level. Comparing means 103 outputs a defrosting command signal until the defrosting return level /Lc is reduced after defrosting, and signal delaying means 104 outputs the defrosting command signal after delaying generation and termination of the defrosting command signal by a predetermined time, respectively. ,this·
The present invention is characterized by comprising a defrosting means 105 that defrosts the evaporator while the defrosting command signal is output from the signal delay means.

The signal delay means 104 includes a delay circuit 111 that delays and outputs the defrosting command signal outputted from the comparing means 103, and a delay circuit 111 that delays the generation of the defrosting command signal outputted from the comparing means 103, and delays the disappearance of the defrosting command signal obtained through this delay circuit. a delay circuit 112 for outputting
And, it can be constituted by an OR circuit 113 which takes the OR of the outputs of both of these d extension circuits.

[Embodiments of the invention]

FIG. 2 is a circuit diagram showing the configuration of an embodiment of the present invention, which mainly includes a light emitting element D and a phototransistor D, and includes a frost detection device 21 (not shown) that detects the formation of an evaporator 1ffi, and a variable resistor vR. and a level setter 22 that applies a voltage across a series circuit of a resistor R3 and outputs a defrost start level signal LA and a defrost return level signal L8 by changing the variable resistor ■8 or the applied voltage; and an operational amplifier OP; A comparison circuit 23, which is composed of a Zener diode ZD and a lower transistor 2, etc., compares the output of the frost detection bag W121 with the output of the level setting device 22 and outputs a defrosting command signal, and a rising edge of this defrosting command signal. A timer TIM1. Another timer TIM2 that delays the falling edge of the defrosting command signal output from this timer by 12 hours, a signal delay circuit 24 consisting of an OR circuit OR that takes the logical sum of both of these timers, and a transistor T3. 'ltj and a series circuit of the relay REL, and a defrost circuit 25 that closes the contact of the relay REL and energizes the four-way valve 26 while the defrost command signal is output from the signal delay circuit 24. has been done.

The operation of this embodiment configured as described above will be explained below with reference to the time chart of FIG.

First, when the frost attached to the evaporator grows, the frost detection device 2
The output signal of 1 rises as shown in FIG. 3(a). When this output signal exceeds the defrosting start level L set by the level setter 22 at time [1], the comparison circuit 23
The output level of operational amplifier OP of is inverted from rHJ to rLJ, and the level of the collector of transistor T2 is inverted from rLJ to rHJ. Thus, the comparison circuit 23 outputs a defrosting command signal.

Next, this defrosting command signal is applied to the delay circuit 24, where the signal whose rise is delayed by time T4 by timer TIM1 is applied to the OR circuit OR, so that the signal is delayed by time T1 with respect to time t1. A defrost command signal is applied to the defrost circuit 25.

In the defrosting circuit 25, in response to this, the relay REL excites the four-way valve 26, so that the refrigerant temporarily flows in the opposite direction.
This starts defrosting.

When the amount of frost formation decreases due to this defrosting, the output of the frost detection device 21 decreases as shown in FIG. From this point on, the output level of the comparison circuit 23 becomes rH.
Flip from J to rLJ. Therefore, the defrosting command signal disappears, but its disappearance is delayed by 12 hours due to the action of the timer TlM2O of the delay circuit 24. In other words, defrosting continues for 12 hours even after the defrosting return level L 1 has passed.

Since FIG. 3(b) shows these jumps, the defrosting operation is performed with a delay of T1 time from the time t1 when the output of the frost detection device 21 exceeds the defrosting start level LA set in the level setting device 22. Further, the output of the frost detection device 21 reaches the defrosting return level set in the level setting device 22, and defrosting ends 12 hours later than time t2.

The reason why the start and end of defrosting are delayed by a predetermined period of time will be explained below.

In Figure 3, if the defrost start level is set high, it is advantageous in that the period of cold W operation vg becomes longer, but if the frost density is sparse, even if a considerable amount of frost forms, The output of the detection device may not rise to the defrosting start level L, causing inconvenience. On the other hand, excluding 'JIAr
If #j start level L is extremely lowered, there will be an inconvenience that frequent defrosting operations will be required as described above.

Therefore, in this embodiment, the defrost start level LA is set to a level that allows the amount of snow to be reliably detected even if the frost density changes, that is, the defrost start level LA is set slightly lower than that of the conventional device, and frost formation is detected. However, the above-mentioned inconvenience is solved by starting defrosting only after the predetermined time T1 has elapsed.

On the other hand, if you set the defrost return level to a high level, the cooling operation will begin shortly after defrosting starts, which may result in residual frost.On the other hand, if you set it to a low level, the frost sensing device will It is also possible that the output does not decrease.

Therefore, in this embodiment, the defrost return level L8 is set slightly higher than that of the conventional device, and the defrost operation is performed for an extra 12 hours after detecting that most of the frost has been removed. This avoids unnecessary switching between defrosting and cooling, and ensures reliable defrosting.

In this way, effective defrost control can be performed by using both the frost detection device and the timer.

Next, FIG. 4 is a block diagram showing the configuration of another embodiment of the present invention, in which the output signal of the frost detector 31 that optically detects the amount of frost in the same way as described above is transmitted to the A/D converter. Via 32,
The data is imported into the microcomputer 33.

The microcomputer 33 performs the same processing as described above using a built-in program.
FIG. 5 shows the processing procedure.

That is, after the power is turned on, it is determined whether the output of the frost detection device 31 has reached the pre-stored defrost start level L (step 40), and if it has reached the defrost start level, When T1 time has elapsed from that point, a defrosting command signal is output to start defrosting and continue it (steps 41 to 44).

Next, it is determined whether the output signal of the frost detection device 31 has reached a pre-stored defrost return level (step 45). If the temperature has fallen below the defrosting return level, defrosting is terminated when 12 hours have elapsed from that point (steps 46 to 49).

The functions shown in the flowchart of FIG. 5 clearly correspond to the functions of the block diagram shown in FIG. 1 above.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, since the frost detection means and the one-word delay means are used together, it is possible to defrost reliably regardless of the frost density, and The number of times defrosting can be reduced, and furthermore, it is possible to perform appropriate defrosting without residual frost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, Fig. 3 is a time chart for explaining the operation of the embodiment, and Fig. 4 is a block diagram showing the structure of the present invention. FIG. 5 is a block diagram showing another embodiment of the present invention; FIG. 5 is a flowchart for explaining the operation of the same embodiment; FIGS. FIG. 8 is a block diagram of a conventional defrosting 11i1NI1 device. 21.31...Frost detection device, 22...Level setter, 23...Comparison circuit, 24...Delay circuit, 25...
- Defrosting circuit, 26... Four-way valve, 32... A/D conversion switch, 33... Microcomputer. Applicant's agent Kiyoshi Inomata 90

Claims (1)

[Claims] a frost detection means for optically detecting the amount of frost on the evaporator; a level setting means for outputting a defrost start signal and a defrost return signal at a level corresponding to the amount of frost on the evaporator according to settings; a comparison means that compares the outputs of the setting means and the frost detection means and outputs a defrost command signal from when the amount of frost builds up to a defrost start level until it decreases to a defrost return level; and this defrost command signal. The evaporator is provided with a signal delay means for delaying and outputting the occurrence and end of the evaporator by a predetermined time, and a defrosting means for defrosting the evaporator while the defrosting command signal is being output from the signal delay means. A defrosting control device characterized by: