JPS6024900A - Dryer control method - 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 method for controlling a dryer that dries clothes and the like using hot air.

Conventional configuration and its problems Traditionally, clothes dryers were often used in areas with special weather conditions such as the Hokuriku region, but due to changes in housing conditions in recent years, they are now often used in ordinary households regardless of region. It's starting to look like this. Under these circumstances, energy-saving and
Many requests have been raised in terms of usability. In other words, since dryers require a relatively large amount of thermal energy, there is a large energy loss due to excessive setting of the timer.
There is a desire to freely set the drying state for purposes such as ironing.

In order to meet these demands, many methods have been proposed to automatically determine the drying state and control the dryer, and some methods have been incorporated into some products, but each method has advantages and disadvantages and many problems. The reality is that we have points.

Two methods that have been proposed so far include methods for detecting the surface resistance of clothing using electrodes. In this method, a pair of mutually insulated electrodes is provided in a drying cabinet, and the surface resistance of the clothing is detected by the pair of electrodes to detect the dry state. This method can be said to be a reliable method as it directly detects the surface condition of the clothes, but in order to evenly detect the clothes in the dryer, it requires a large number of electrode pairs, which is very expensive. It is merely a provision.

For this reason, if the amount of one type of clothing differs, the contact state and frequency of contact between the electrode and the clothing will differ, making it difficult to stably determine the dry state.

Furthermore, since static electricity generated when clothes are dried is applied between the electrodes, there is a fear that the electronic circuit that detects the resistance between the electrodes may be destroyed.

Further, as another conventional method, a method has been proposed in which the dry state is determined based on the temperature of the exhaust gas discharged after drying. However, the detection accuracy of this method varies greatly depending on the ambient temperature. Additionally, in order to eliminate this drawback, a method has been proposed that detects the ambient temperature and makes a determination based on the difference between the exhaust temperature and the ambient temperature, but this method requires two sets of temperature sensing elements and is expensive. There is a drawback.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a method for controlling a dryer that allows stable and inexpensive detection of the dry state.

Structure of the Invention The present invention provides a method for controlling a dryer that determines the progress of drying based on the rate of change in the exhaust temperature of the dryer detected by an exhaust temperature detection device and the output of a timer that measures the drying time. This is what we are trying to achieve.

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

In FIG. 1, reference numeral 1 denotes a temperature detection device for the exhaust gas discharged through clothes, etc. of the dryer. 2 is a means for calculating the rate of change in the exhaust gas temperature detected by the exhaust gas temperature detection device 1, and in this embodiment, it includes a timer 3 for measuring drying time, and a distributor 4. It is composed of a storage device 5 and a subtractor 6. 7 inputs the rate of change of exhaust temperature and the output of timer 3,
The control device determines the progress of drying based on these two pieces of information.

Next, a specific method for determining the progress of drying using the above method will be described.

Generally, as shown in Figure 2, the progress of drying is divided into a preheating period Y during which the temperature of the material to be dried rises, and a constant rate drying period during which the temperature of the material to be dried remains almost constant and the drying efficiency is highest. The drying period is divided into a decreasing rate drying period G during which most of the moisture contained in the dried material is removed and the temperature of the dried material rises again. During the preheating period Y, the dried material is hardly dehumidified, and most of the applied heat is consumed to raise the temperature. During the constant rate drying period K, most of the applied heat is consumed as latent heat of vaporization, so dehumidification is performed most efficiently although the temperature remains almost constant. In the decreasing rate drying period G, the proportion of heat consumed by latent heat of vaporization gradually decreases, and the proportion consumed by temperature rise gradually increases. During this period, the rise in exhaust gas temperature can be as high as 3 depending on the amount of load.
It will look like Figure 5. Figure 3 shows that when the load is light, the 4th
The figure shows the case when the load is medium, and FIG. 5 shows the case when the load is heavy.

The progress of drying at this time is as shown in FIG.

A is when the load is light, and 9 is when the load is medium.

C is a case where the load is heavy. Here, from Figures 3 to 6 and Figure 6, the relationship between drying rate and exhaust temperature is illustrated.
As shown in the figure, almost one correlation line is drawn regardless of the load.

In other words, the rate of increase in temperature during the preheating period, constant rate drying period, and decreasing rate drying period is correlated with the quantity and quality of the fabric and the speed at which twist drying progresses. If the ambient temperature changes, the correlation line will shift in parallel depending on the ambient temperature as shown in Figure 8, but the preheating period, constant rate drying period, lapse rate drying period, and rate of change in temperature are independent of the ambient temperature. It is.

Therefore, if it is possible to detect the rate of change in temperature, that is, the rate of increase in exhaust temperature during the preheating period, constant rate drying period, or lapse rate drying period, it will be possible to determine the speed of drying progress, regardless of the ambient temperature. Control such as stopping the equipment in an appropriate dry state becomes possible. For example, the above preheating period,
The constant rate drying period is determined as the preheating period until the rate of change in the exhaust gas temperature becomes less than a certain value, and then the rate of change in the exhaust gas temperature becomes less than a certain value and again becomes greater than a certain value. The period until the end of the constant rate drying period is judged as the constant rate drying period, and the drying end time is predicted based on the time until the end of the preheating period or the constant rate drying period and the equipment is stopped, or the rate of increase or change in exhaust temperature during the decreasing rate drying period is determined. Completion of drying can be determined based on the drying time and the drying time.

Also, the drying rate at point A in Figures 7 and 8, that is, the time when the constant rate drying period changes to the decreasing rate drying period, is approximately 90%.
Therefore, it is sufficient to detect the drying state and control the dryer substantially during the lapse rate drying period.

Therefore, if there is a method of determining the progress of drying based on the product of the rate of change in exhaust gas temperature during the lapse rate drying period and a timer that measures the drying time, that is, t-possible T≧C... ■ t: Time T: Exhaust temperature C: If it is determined that the drying has ended or is in a certain drying state when it is constant, the progress state of drying can be determined without having to judge the preheating period, constant rate - drying period, or lapse rate drying period. The meaning of the formula 0.0 is that by multiplying the load by the time t, the drying rate is determined by comparing it with a constant value C, regardless of the load. That is, in FIGS. 3 to 6, when the tO'dtO value is constant, the drying rate is approximately constant tl.

In addition, according to the method of determining the time to stop the equipment based on the time tk until the end of the constant rate drying period, that is, if the operating time of the dryer is 1a, then 1 = f (tk), then the time at the end of drying It becomes possible to freely select the drying state. or,
If we assume that the count start of the timer that measures t in the formula and tk above is when the dryer starts operating, then when the dryer is operated continuously, the temperature of the dryer body will be the same as the first time even if the load is the same. Since there is a large difference in the second time, there will be some errors in the progress of drying due to the large difference in the length of the preheating period. Therefore, more accurate determination can be made by setting the timer to start counting when the rate of change in the exhaust gas temperature becomes less than a certain value, that is, when the constant rate drying period starts.

Note that the method of determining the rate of change in exhaust gas temperature and calculations with respect to time can be easily and inexpensively realized using microcomputers, which have become available at low cost in recent years. In other words, the timer, distributor, storage device, subtracter, and control device in FIG. 1 can be implemented by a 1+ microcomputer for real/current use.

Effects of the Invention The present invention uses a timer that measures the rate of change in exhaust temperature and drying time to determine the constant rate drying period, and also detects the time during this period or the rate of increase in exhaust temperature during the decreasing rate drying period. By doing so, it is possible to accurately determine the carrying state of drying with a single temperature detection device, so the operation control of the dryer can be performed stably, inexpensively, and appropriately, resulting in energy savings.2. The time-saving effect can be fully demonstrated.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a control method for realizing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the relationship between the progress of drying and exhaust temperature, and Figs. 3 to 5 show the load An explanatory diagram of the relationship between the drying progress state and exhaust temperature at different times, Figure 6 is a diagram of the relationship between drying time and drying rate under the conditions of Figures 3 to 5, and Figure 7 is an illustration of the relationship between the drying progress state and exhaust temperature at different times. Figure 6 is a diagram of the relationship between the drying rate and exhaust temperature determined from Figure 6. Figure 8 is a diagram of the relationship between the drying rate and exhaust temperature when the ambient temperature is changed. Temperature detection device, 2... Means for measuring the rate of change in exhaust temperature, 7... Control device. Name of agent: Patent attorney Toshio Nakao and 1 other person81
Figure 2 Figure 4 Figure 5 Figure 6 Time Figure 7 Figure 8 Time rate

Claims (4)

[Claims] (1) A dryer control method that determines the progress of drying based on the rate of change in the exhaust temperature of the dryer detected by an exhaust temperature detection device and the output of a timer that measures the drying time. (2) The method of controlling a dryer according to claim 1, wherein the progress state of drying is determined based on the multiplication value of the rate of change in exhaust gas temperature and the output of a timer for measuring drying time. (3) The drying process according to claim 1, wherein the progress state of the drying is determined by the output of a timer that measures the drying time until the rate of change in the exhaust gas temperature falls below a certain value and becomes above the certain value again. How to control the machine. (4) A method for controlling a dryer according to claim 1, wherein the timer for measuring drying time starts counting when the rate of change in exhaust gas temperature becomes below a certain value.