JPS6213040B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of controlling a dryer for drying clothes and the like with hot air.

Structure of conventional dryers and their problems Generally, when drying clothes, the drying time varies depending on the amount and type of cloth, so conventional dryers use a timer, which the user deems appropriate based on past experience. It was set on time.

However, if you set the timer incorrectly,
There were cases where the cloth was over-dried and damaged, or the cloth was not dried at all. It should be noted that it would be uneconomical if it became too dry. There is also a method of detecting dryness by detecting the resistance value of the cloth, but since the resistance value of the surface of the cloth is detected with electrodes, there is a risk that the cloth will not dry properly if the cloth is thick. If the amount was small, the cloth may not touch the electrode, and in this case dryness could not be detected. Furthermore, since the method detects the surface resistance of cloth, it is necessary to detect a very high resistance value, which causes various problems in terms of circuitry.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
To provide a method for controlling a dryer that can inexpensively detect a specified drying rate regardless of the type of cloth or the amount of cloth.

Structure of the Invention The dryer control method of the present invention stores the time when the rate of change in exhaust gas temperature reaches a specified value, and calculates the rate of change in exhaust gas temperature even after the rate of change reaches the specified value. If the rate of change becomes negative, it is determined that the temperature has increased due to an abnormality such as cloth entanglement and the rate of change has reached the specified value, and the time when the rate of change of the exhaust temperature reaches the specified value is ignored. Then, find the time for the rate of change to reach the specified value again. Then, when the rate of change does not become negative after reaching the specified value, the specified drying rate is detected. With this method, a specified drying rate can be obtained without malfunctioning due to a rise in temperature due to some cause such as entanglement of cloth.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention. 1 is an exhaust temperature detection device that detects the exhaust temperature of the dryer. 2 is an operating time counting device that counts the operating time of the dryer from the start of operation. 3 is an arithmetic and control device that receives the output of the exhaust gas temperature detection device 1, calculates temporal changes, and calculates the rate of change. Further, this arithmetic and control device 3 receives the output of the operating time counting device 2, calculates the operating time by putting it into a prescribed function, compares the rate of change in the exhaust gas temperature with the calculated value of the operating time, and uses the result to determine whether the dryer The heater 4 or motor 5 is stopped or continues to operate.

FIG. 2 shows how the exhaust temperature changes as drying progresses. At time _t1 , the amount of heat given during the preheating period does not contribute much to drying, and the exhaust temperature rises rapidly. During period _t2 , the amount of heat given during the constant rate drying period is taken away by the latent heat of vaporization of moisture, and the exhaust temperature becomes constant. This is the most efficient way to dry. Period _t3 is a lapse rate drying period, where the fabric is almost dry and the exhaust temperature increases.

Figure 3 shows the rate of change curve of exhaust gas temperature. Third
Point P' in the figure is the point where the drying rate is approximately 90% and the constant heat drying period shifts to the decreasing rate drying period. P' point is the second
This corresponds to point P in the figure.

This point P' is on the function ΔT/Δt=-At+B of the operating time t of the dryer, which was determined by experiment.

Δt is a change in operating time, ΔT is an amount of change in exhaust gas temperature during the change in operating time Δt, and A and B are constants.

Therefore, if the drying rate is detected except during the preheating period _t1 , when the rate of change in the exhaust gas temperature is equal to or higher than the detection straight line 6 determined by the function of the operating time t - At+B,
The drying rate becomes approximately 90% at the time of transition from the constant rate drying period to the decreasing rate drying period.

In addition, even if you experimentally find a constant value C instead of -At+B, which is determined from the operating time, and detect the drying rate when the rate of change in exhaust gas temperature reaches the constant value C, it will not work regardless of the amount or type of fabric. A drying rate of approximately 90% can be obtained. If a drying rate of 90% can be detected, a delay time can be determined based on the time it takes for the drying rate to reach 90%, and operation can be delayed for a specified period of time to achieve a drying rate of 100%.

FIG. 4 shows a case where the exhaust temperature changes due to entanglement of cloth. The convex portion 7 of the exhaust gas temperature T is a change in the exhaust gas temperature caused by the entanglement of the cloth. The rate of change in exhaust gas temperature in this case is shown in FIG.

There is a point at P ₁ ' where the magnitude of the rate of change in exhaust gas temperature ΔT/Δt exceeds the standard line 8 for determining, that is, ΔT/Δt=-At+B, and before the true drying rate detection point P ₂ ' is detected. Detects P ₁ ′, 90% even though it is not dried
Emit a detection signal.

However, when the exhaust temperature rises due to tangled cloth, the temperature inevitably falls because the tangled cloth becomes untangled or the tangled cloth moves to another location. Therefore, at this time, the rate of change in exhaust gas temperature becomes negative (point 9 in FIG. 5). When the rate of change in the exhaust temperature becomes negative, the point in time when dryness has already been detected is removed and the detection operation is performed again.

In other words, 90% detection was performed at P ₁ ′, and then the operation moved to 100% detection after driving for a specified time, but since the rate of change became negative at 9 points, P ₁ ′ was abandoned and the detection operation was performed again. 90% detection is performed by detecting P ₂ ′. Even after P ₂ ' is detected, the rate of change in exhaust gas temperature is calculated until the drying rate reaches 100%, and monitored to see if it becomes negative. If the value does not become negative, the operation that was started for 100% drying rate detection is continued after P ₂ ′, and 100% drying rate detection is performed.

If the rate of change becomes negative after P ₂ ′ is detected, the P ₂ ′ point is ignored and the 90% detection operation is started again.

As described above, by determining a predetermined drying rate from the rate of change in the exhaust gas temperature of the dryer, it is possible to prevent malfunctions due to clumps of cloth and to perform inexpensive and reliable dryness detection.

Effects of the Invention The dryer control method of the present invention detects dryness by determining the rate of change in the exhaust temperature of the dryer and detecting whether the rate of change in the exhaust temperature becomes negative after the rate of change reaches a specified value. This prevents malfunctions caused by clumps of cloth, and provides reliable dryness detection at low cost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a dryer control method showing an embodiment of the present invention, Fig. 2 is a dryer exhaust temperature change characteristic diagram, and Fig. 3 shows the exhaust gas temperature change in Fig. 2 per unit time. Figure 4 is the exhaust temperature change rate characteristic diagram calculated based on the rate of change. Figure 4 is the exhaust temperature change characteristic diagram during abnormal conditions. Figure 5 is
The figure is an exhaust gas temperature change rate characteristic diagram in which the exhaust gas temperature change in FIG. 4 is calculated as a rate of change per unit time. 1...Exhaust temperature detection device, 3...Arithmetic control device.

Claims (1)

[Claims] 1 Detect whether the rate of change in the exhaust temperature of the dryer becomes negative after the rate of change in the exhaust temperature of the dryer reaches a specified level, and when it becomes negative, it is determined that the rate of change in the exhaust temperature has reached the specified level. A dryer control method that ignores time and measures the time for the rate of change in exhaust temperature to reach a specified level again, and when it does not become negative, detects the specified drying rate.