JPS5915786A - Controller for heater of 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 Page 2 The present invention relates to a heater control device for a dryer that is equipped with a heater for heating air for drying and detects the resistance value of a material to be dried using an electrode in a drying chamber.

FIG. 1 shows the change in drying rate over time, and as shown, it can be seen that there are three periods in which the drying rate changes. The first period indicated by a is called a preheating period, the second period indicated by b is called a constant rate drying period, and the third period indicated by C is called a decreasing rate drying period.

During the preheating period a, heat is used to raise the temperature of the material to be dried and the dryer main body, so the drying rate hardly changes. During the constant rate drying period, water constantly evaporates and the drying rate increases linearly. The decreasing rate drying period C is a period in which most of the moisture evaporates and the temperature of the material to be dried and the main body of the dryer increases, and the change in the drying rate becomes small.

Here, the constant rate drying period is a period in which moisture evaporates steadily, and it is thought that it is only necessary to supply latent heat of evaporation, and the moisture evaporates by simply providing the minimum amount of heat that maintains the temperature inside the aircraft. It is considered that

Moreover, as shown in FIG. 1, it has been experimentally found that when the drying rate is 70 to 763 pages, the first period a shifts to the second period A.

The present invention detects the resistance value of the object to be dried using electrodes in the drying chamber, detects a predetermined drying rate, for example, 70 to 76 inches, detects the initial stage of the constant rate drying period, and then turns the heater on. This reduces the amount of heat generated to maintain the temperature inside the aircraft.

The purpose of this is to make the drying time comparable to the case where the amount of heat generated by the heater is not reduced, thereby achieving efficient drying.

Conventionally, when using a dryer, a user sets the strength of the shirring heater at the start of operation, depending on the weight of the material to be dried, etc., and operates the dryer at the same setting until the end of drying. This consumes power unnecessarily and is inefficient.

The present invention makes the drying time comparable to that of the conventional method and makes the power consumption of the heater more efficient.

The present invention has a basic configuration as shown in FIG. 2, in which 1 is means for converting the resistance value of the object to be dried detected by an electrode in the drying chamber into an electric signal, and 2 is a reference voltage setting section. The voltage obtained by the means 1 for converting the resistance value of the object to be dried into an electric signal and the voltage obtained by the reference voltage setting section 2 are compared by the comparison means 3, and the electric signal obtained thereby is used to control the control means 4. is operated to control the heater 5 for heating the drying air. The control means 4 includes a reference voltage setting section 2
If the drying rate of the material to be dried reaches 70 to 75% or more using the set voltage, the heater 6 is controlled to such an extent that the temperature inside the machine can be maintained.

Next, specific examples of the present invention will be described. In the electrical circuit shown in FIG. 3, the voltage obtained by the means 1 for converting the resistance value of the object to be dried into an electrical signal and the voltage set by the reference voltage setting section 2 are compared by a comparator 3, which is a comparing means, When the voltage obtained by the means 1 for converting the resistance value of the object to be dried into an electrical signal becomes smaller than the set voltage of the reference voltage setting section 2, the output of the comparator 3 becomes zero level,
Relay 4 operates to open its relay contact 4' and reduce the amount of heat generated by heater 5.

Here, when the voltage obtained by means 1 for converting the resistance value of the object to be dried into an electric signal becomes smaller than the set voltage of the reference voltage setting section 2, the drying rate of the object to be dried is 7.
The set voltage is set so as to reach 0 to 75%. As a result, the amount of heat generated by the heater 5 can be reduced after the drying rate of the material to be dried is 70 to 76%, that is, after the constant rate drying period.

The means 1 for converting the resistance value of the object to be dried into an electrical signal is composed of resistors 6, 7, 8, and 9, an operational amplifier 10, a capacitor 11, an electrode 12, and a capacitor 13. Note that the resistor 6.7 is a resistor for preventing electric shock. The electrode 12 detects the resistance of the object to be dried in the drying chamber, and inputs a voltage divided by the resistance value of the resistor 8 and the object to be dried in the drying chamber to a voltage follower formed by an operational amplifier 10. The capacitor 11 is for preventing induction. The output of a voltage follower by an operational amplifier 10 is smoothed by a resistor 9 and a capacitor 13.

The reference voltage setting section 2 sets a reference voltage using resistors 14 and 15. This reference voltage has a drying rate of 70
75%, the voltage value is obtained by the means 1 for converting the resistance value of the material to be dried into an electric signal and is 6 degrees. In addition, 16 is a motor that rotationally drives a drum serving as a drying chamber and a fan for moving drying air;
7 is an AC power supply.

Figure 4 shows the relationship between drying rate and interelectrode resistance, and
FIG. 5 shows the relationship between the drying rate and the voltage V obtained by means 1 for converting the resistance value of the object to be dried into an electrical signal. The reference voltage setting value is vl in FIG.

As described above, the present invention detects when the drying rate of the material to be dried is a predetermined value, for example, 70 to 75%, using an electrode in the drying chamber, so that the amount of heat generated by the heater can be adjusted after the start of the constant rate drying period.
This controls the heater so that it is kept small enough to maintain the temperature inside the machine. As a result, the drying time can be made comparable to that in the case where the amount of heat generated by the heater is not reduced after the start of the constant rate drying period, and drying can be performed efficiently.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the change in drying rate over time, Fig. 2 is an electrical block diagram showing the configuration of the present invention, Fig. 3 is an electrical circuit diagram in an embodiment of the present invention, and Fig. 4 is a Y page drying FIG. 5 is a diagram showing the relationship between the drying rate and the resistance value H between the electrodes, and FIG. 1... Means for converting the resistance value of the object to be dried into an electrical signal, 2... Reference voltage setting section, 3...
Comparison means, 4... Control means, 5... Heater, 12... Electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3

Claims (2)

[Claims] (1) A heater for heating air supplied into the drying chamber, an electrode provided in the drying chamber to detect the resistance value of the object to be dried, and a means for converting the resistance value of the object to be dried into an electrical signal. a reference voltage setting section; a means for comparing an electrical signal obtained by the reference voltage setting section with an electrical signal obtained by the means for converting the resistance value of the dried material into an electrical signal; A heater control device for a dryer, comprising: control means for controlling the heater based on the obtained electric signal. (2) The control means for controlling the heater obtains an electric signal by the comparison means when the drying rate of the material to be dried is 70 to 75%,
The dryer heater control device according to claim 1, which controls the amount of heat generated by the heater after that time.