JPS581960B2 - Dryness detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting dryness in a dryer for drying laundry, etc., in which a drying chamber 1 is provided with an intake port 2 for taking in external air and a discharge port 3 for discharging internal air. Inside mouth 2 and outlet 3
The temperature and relative humidity inside the air inlet 2 are measured, and the absolute humidity inside the air inlet 2 and the air outlet 3 are detected.
This relates to a dryness detection method characterized by comparing the difference between the absolute humidity inside the discharge port 3 and the absolute humidity inside the discharge port 3.

Conventionally, the method of detecting the drying of laundry or other items to be dried in a drying chamber is to measure the relative humidity of the air discharged from the drying chamber, and if this value falls to a set value, it is determined that drying is complete. Measures were taken to cut off the circuit and turn off heating means such as heaters in the drying chamber.

However, with this method, if the humidity of the air taken into the drying chamber increases, the relative humidity of the discharged air also increases, so dryness cannot be detected even though the material to be dried is dry. When the humidity decreases, a drying completion signal may be issued even when the drying of the object to be dried is not completed, which has the drawback that accurate detection cannot be performed.

Furthermore, this method has the disadvantage that it is practically inconvenient because it is necessary to set a relative humidity setting value for cutting off the circuit of the heating means in accordance with the humidity that varies from day to day.

On the other hand, in addition to this method, there is also a method of detecting the dry state by measuring the electrical resistance of the object to be dried.This method allows for more accurate detection than the above method, but Direct contact is necessary, which may cause deterioration of the contact portion, and the measured value varies depending on the position of contact with the object to be dried, and the troublesome work of setting it on the object to be dried is also required.

The present invention has been developed in view of the above points, and is capable of accurately detecting the drying state regardless of the humidity of the air taken into the drying chamber, and also allows setting of daily setting values and The object of the present invention is to provide a method for detecting dryness that does not require any work such as setting.

The present invention will be explained in detail below with reference to Examples.

As shown in FIG. 1, a drying chamber 1 has an intake port 2 and a discharge port 3 open therein, and an exhaust blower 4 is attached to the discharge port 3.

5 is a heating means such as an electric heater. This dryness? When drying laundry or other items to be dried 6 in a container, heat in 1,000 steps 5.
External air is drawn into the drying chamber 1 by heating and driving the exhaust blower 4, and humid air generated from the material to be dried 6 is discharged from the discharge port 3.

The present invention detects the drying of the object to be dried 6 in such a dryer by applying the fact that the discharged air contains moisture that evaporates when the object to be dried 6 is dried.

This detection method will be explained based on the flowchart of FIG.

First, the sensor detects the temperature T1 and relative humidity φ1 of the intake port 2.
, the temperature T2 and the relative humidity φ2 of the discharge port 3 are measured,
From the values of T1 and T2, the saturated water vapor pressure hs at each temperature
1=f(T1) and hS2=f(T2) are calculated.

Next, the absolute humidity x1=f(hs1・φ1) of the intake port 2 is calculated from the saturated water vapor pressure hs1 of the intake port 2 and the relative humidity φ1, and the absolute humidity Absolute humidity at outlet 3 X2=f(hs2・φ
2) Calculate.

Comparing the moisture content of the intake air into the drying chamber 1 and the moisture content of the discharge air, when drying is in progress, the moisture content of the discharge air is naturally greater than the moisture content of the intake air, and the absolute moisture content of the intake air The relationship is humidity X1<absolute humidity at the discharge port X2.

When drying is completed and no moisture is generated from the material to be dried 6, the moisture content of the intake air and the moisture content of the discharged air become equal.
Therefore, x1=x2.

Therefore, a comparison circuit is formed to electrically compare the values of X1 and X2, and when x1<x2, the dryer continues to operate, and x
When 1=x2, the operation of the dryer is stopped, such as by cutting off the circuit to the heating means 5.

In this way, in the present invention, the dry state is detected by comparing the difference between the absolute humidity, which is the moisture content of the intake air into the drying chamber, and the absolute humidity, which is the moisture content of the discharged air. It is possible to accurately detect a dry state without being affected by air humidity, and it is also possible to detect a dry state without being affected by daily atmospheric humidity.

Furthermore, there is no need to bring an electrode or the like into contact with the object 6 to be dried during measurement, no deterioration of equipment parts occurs, and no troublesome work is required.

Note that measurement is not limited to continuous or intermittent measurement.

In addition, it takes a considerable amount of time for the moisture in the dried material to completely evaporate, and considering the relationship between time and moisture content, the evaporation rate corresponding to the passage of time becomes extremely small after a certain limit, making it impractical for practical use. Even though it is considered that the dry state is sufficiently dry, it is wasteful to detect a small amount of moisture and continue the drying process, and more precisely, X1 = X2
Since it is considered that this is unlikely to occur, it is conceivable to give an appropriate difference to X1 or an appropriate addition to X2 when inputting to the comparison circuit for practical use.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a dryer applied to the present invention, and FIG. 2 is a flowchart of the same method. 1 is a drying chamber, 2 is an intake port, and 3 is a discharge port.

Claims (1)

[Claims] 1 A drying chamber is provided with an inlet for taking in external air and an outlet for discharging internal air, and the temperature and relative humidity inside the inlet and the outlet are measured respectively to determine the absolute humidity inside the inlet and the outlet. A dryness detection method characterized by detecting and comparing the difference between the absolute humidity inside the intake port and the absolute humidity inside the discharge port.