JPS60139299A - Controller for clothing drier - 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 Field of the Invention The present invention relates to a control device for a clothes dryer that dries clothes and the like with hot air.

Conventional Structure and Problems Generally, in a clothes dryer for drying clothes, the drying time differs depending on the amount and type of clothes. For this reason, the conventional clothes dryer has to be equipped with a warm-up timer, and the user has to set the operating time of the dryer using the timer.

In this case, if the time setting is incorrect, the clothes may become overdried and damaged, or may remain undried.

In response, a method has been proposed in which the dry state is detected and the operation is controlled by detecting the resistance value of the clothes with electrodes, but resistance value detection may be insufficient when drying thick clothes. In addition, there were cases where it was determined that the drying process was completed even though the drying process was not yet completed. Furthermore, when drying a small number of clothes, the contact between the clothes and the electrodes is reduced, making it difficult to detect the dry state.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional clothes dryer and provides a dryer control device that reliably detects the drying completion state and controls the operation regardless of the type of clothes or the amount of clothes. That is.

Structure of the Invention In order to achieve the above object, the dryer control device of the present invention includes an exhaust temperature detection device that detects the exhaust temperature, a calculation device that reads the output of the exhaust temperature detection device on two or more floors, and a calculation device that detects the exhaust temperature. a comparator that compares the output signal of the device with a predetermined value table and outputs a control signal when the output signal of the arithmetic device becomes less than or equal to a predetermined value; and a control means that stops the operation based on the output signal from the comparator. With this, it is possible to accurately detect the completion state of drying of the object to be dried.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an exhaust temperature detection device for detecting the exhaust temperature T of the dryer, which is comprised of a heat-sensitive element such as a thermistor. 2
is a timer device that outputs a pulse every predetermined unit time.

3 is an arithmetic unit which receives the output of the exhaust temperature detection device 1 and the output pulse of the timer device 2, calculates the rate of change dT/dt of the exhaust temperature T per predetermined unit time, and further calculates the rate of change dT/dt of the rate of change dT/dt. The rate of change dt/dt per unit time is calculated.

4 is a comparator and the rate of change dt2/d is the output of the arithmetic unit 3.
2t to predetermined value V to comparison, change ([When Jdt2/d2t becomes less than the predetermined value V, a control signal is output.

, 6 is a control means that stops energizing the heater 6 and motor 7 when a control signal from the comparator 4 is input.

Next, the operation in the above configuration will be explained.

When the drying operation is started, the exhaust gas temperature T gradually rises as shown in FIG. In FIG. 2, A indicates a preheating period, B indicates a constant rate drying period, and C indicates a decreasing rate drying period. Further, R indicates the drying rate, and point P indicates the desired drying rate.

As is clear from FIG. 2, the exhaust gas temperature T rises rapidly during the lapse rate drying period. Then, this exhaust gas temperature is detected by the exhaust gas temperature detection device 1, and the output from the exhaust gas temperature detection device 1 is inputted to the calculation device 3, whereby the rate of change dT/dt of the exhaust gas temperature is first calculated. FIG. 3 shows the characteristics of the rate of change in exhaust gas temperature dT/dt. In this calculation device 3, the rate of change d of the exhaust gas temperature is
A rate of change dT/dt is calculated by further differentiating T/dt.

The characteristics of this second-order differential value dT2/d2t are shown in FIG.

This rate of change dT2/d2t is input to a comparator 4 and compared with a predetermined value V. Since the exhaust temperature T has an inflection point in the preheating period A and the lapse rate drying period C, the second differential value dT/dt changes from positive to negative in the preheating period A and the lapse rate drying period C, as shown in Figure 4. Changes to

However, during the preheating period A, the inflection point does not appear, or even if it does appear, the value of the second-order differential value dT/dt is small. Therefore,
If the predetermined value V is set appropriately, a control signal will be output from the comparator 4 when the second-order differential value dT/dt becomes less than the predetermined value V.
The control means 5 is actuated by this control signal, and electricity is cut off to the heater 6 and motor 7, and the operation is completed. Note that, in actual use, second-order differentiation is sufficient for the arithmetic unit 3, but it may perform more differentiation if necessary.

In this way, the operation is controlled using the exhaust temperature as an input signal, so it is not affected by the type of clothing or clothing.
It is possible to accurately detect the drying completion state of clothes. In addition, in the case of second-order differential, dryness can be detected after t3 as shown in Figure 3, but in the case of first-order differential, dryness can also be detected between t2 and t3, as is clear from the characteristics in Figure 3. This may result in malfunction.

Further, the predetermined value V may be arbitrarily set by the user, and thereby the operation can be stopped at a desired drying rate.

Effects of the Invention As is clear from the above explanation, according to the present invention, it is possible to detect the completion of drying only by using the exhaust temperature as an input signal, and therefore it is not affected by the type or amount of the material to be dried. ,
Accurate detection of drying completion state.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a control device for a clothes dryer showing an embodiment of the present invention, Fig. 2 is a characteristic diagram of the exhaust temperature and drying rate in the clothes dryer, and Fig. 3 is a change in the exhaust temperature. FIG. 4 is a characteristic diagram of the rate of change obtained by second-order differentiation of the exhaust temperature. DESCRIPTION OF SYMBOLS 1... Exhaust temperature detection device, 3... Calculation device, 4... Comparator, 5... Control means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] An exhaust temperature detection device that detects the exhaust temperature; an arithmetic device that differentiates the output of the exhaust temperature detection device by two or more orders; and an output signal of the arithmetic device that compares the output signal of the arithmetic device with a predetermined value to determine whether the output signal of the arithmetic device is the predetermined value. A comparator that outputs a control signal when the following occurs, and this comparison