JPS6147558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for a drum-type dryer or the like that supplies hot air to dry clothing or the like.

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 to set the drying time appropriately based on the user's intuition and experience. It was set. However, if the timer is set incorrectly, the fabric may become over-drying, resulting in higher power consumption than necessary, damaging the fabric, or leaving the fabric undried.

In addition, there is a method to automatically detect the end of drying by detecting the resistance value of the cloth, but since the resistance value of the cloth surface is detected with an electrode, in the case of thick cloth, the cloth Even if the area was dry, there was a risk that the overall condition would be undried. Furthermore, when the amount of cloth is small, the cloth may not touch the electrode, making it impossible to accurately detect the dry state of the cloth. moreover,
Since the method detects the surface resistance of the cloth, it is necessary to detect a very high resistance value, which causes various problems with the circuit.

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

Structure of the Invention The dryer control device of the present invention includes an exhaust gas temperature detection device, an operation time counting device, and an arithmetic control device. Drying control is performed by determining the rate of change in the exhaust gas temperature over time, and comparing the rate of change in the exhaust temperature with the result calculated by the arithmetic and control unit based on the operating time determined by the operating time counting device. , which reliably detects a specified drying rate.

Further, the dryer control device of the present invention includes an exhaust gas temperature detection device and an arithmetic control device, and performs drying control by calculating temporal changes in exhaust gas temperature and comparing the rate of change with a prescribed constant. This method reliably detects the specified drying rate.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes 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 in exhaust gas temperature. Further, the arithmetic control device 3 receives the output of the operation time counting device 2,
The operation time is calculated by putting it into a prescribed function, the rate of change in the exhaust gas temperature and the calculated value of the operation time are compared, and depending on the result, the heater 4 or motor 5 of the dryer is stopped or continues to operate. do.

Figure 2 shows how the exhaust temperature changes as the drying progresses. Period _t1 is the preheating drying period, and the amount of heat applied does not contribute sufficiently to drying.
Exhaust temperature rises rapidly. The period t ₂ is a constant rate drying period, and the applied heat 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.

FIG. 3 shows the relationship between exhaust temperature and time depending on the amount of cloth, and FIG. 4 shows the rate of change of exhaust temperature ΔT/Δt corresponding to FIG. 3.

In Figures 3 and 4, when A has a large amount of cloth,
B indicates when the amount of cloth is medium, and C indicates when the amount of cloth is small.
When the amount of cloth is large, the rate of change in the preheating drying period and the decreasing rate drying period is small and the constant rate drying period is long, so the exhaust temperature change rate ΔT/Δt is small. When the amount of cloth is small C
Since the rate of change in the preheating drying period and the lapse rate drying period is large and the constant rate drying period is short, the exhaust temperature change rate Δ
T/Δt is large. When the amount of cloth is medium, B is in the middle. In Figure 4, the point where the drying rate is approximately 90%
If we connect P ₁ ′ to P ₃ ′ and draw a straight line 6, each point P ₁ ′ to
P ₃ ′ corresponds to the point P ₁ to _{P 3} where the drying period changes from the constant rate drying period to the decreasing rate drying period. The equation of this straight line 6 is ΔT/Δt
It can be expressed as =-At+B. (A, B constants). What this formula means is that when ΔT/Δt is small, t is long and the amount of cloth is large. Further, when ΔT/Δt is large, t is short and the amount of cloth is small.

As described above, data on the exhaust gas temperature T is input from the exhaust gas temperature detection device 1 to the arithmetic and control device 3, and the arithmetic and control device 3 calculates the rate of change ΔT/Δt of the exhaust gas temperature. In addition, the operation time t is calculated from the operation time counting device 2.
The data is input to the arithmetic and control device 3, and the arithmetic and control device 3 calculates At+B. Then, the arithmetic and control unit 3 determines t under the condition that ΔT/Δt≧−At+B, and detects a drying rate of 90%.

Also, during the preheating drying period, the exhaust temperature rises rapidly,
Since the condition of ΔT/Δt≧−At+B is met and false detection occurs, the exhaust temperature detection device 1
stop working. In addition, although the straight line 6 intersecting the exhaust gas temperature change rate curve is drawn in FIG. 4, it may be determined by drawing a curved line.

FIG. 5 shows the case where the hyperbolic curve 7 is drawn.
A indicates a large amount of fabric, B indicates a medium amount of fabric, and C indicates a small amount of fabric. Hyperbolic curve 7 is (t+a)・
It can be expressed as ΔT/Δt=C (a, C constant).

At this time, if the hyperbolic curve 7 does not intersect with the rate of change in the exhaust gas temperature rise during the preheating drying period, there is no need to stop the exhaust gas temperature detection device 1 for a specified period of time from the start of operation.

FIG. 6 shows the case where the rate of change in exhaust gas temperature is constant K. Note that in this example, the operating time counting device 2 shown in FIG. 1 is unnecessary. A is when the amount of cloth is large, B is when the amount of cloth is medium, and C is when the amount of cloth is small.
It can be expressed as T/Δt=K (K constant). At this time,
During the preheating drying period, the operation of the exhaust temperature detection device 1 must be stopped.

Detection formula (t+a) x ΔT/Δt=C and ΔT/
The points where Δt=K intersects with the exhaust gas temperature change rate curve, P ₁ ′, P ₂ ′, and P ₃ ′, are approximately 90% drying at the time of transition from the constant rate drying period to the decreasing rate drying period. .

As described above, since the predetermined drying rate is determined from the rate of change in the exhaust gas temperature of the dryer, the influence of the ambient temperature is small and it is possible to perform inexpensive and reliable dryness detection.

Effects of the Invention The dryer control device of the present invention determines the rate of change in the exhaust gas temperature of the dryer, and detects dryness when the rate of change is a value calculated from the operating time of the dryer or exceeds a specified constant. Only one sensor is required, and dryness can be detected reliably, making it inexpensive and reliable.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a control device showing an embodiment of the present invention, Fig. 2 is a characteristic diagram showing changes in exhaust temperature of a dryer, Fig. 3 is a characteristic diagram showing changes in exhaust temperature depending on the amount of cloth, Figure 4 is a characteristic diagram of the time-exhaust temperature change rate calculated from the exhaust gas temperature change in Figure 3 to the rate of change per unit time, and Figure 5 is a time difference from Figure 4.
FIG. 6 is a characteristic diagram of the time-exhaust temperature change rate showing another example of the present invention. 1...Exhaust temperature detection device, 2...Operation time counting device, 3...Arithmetic control device.

Claims (1)

[Scope of Claims] 1. An exhaust temperature detection device that detects the exhaust gas temperature of the dryer, an operation time counting device that counts the operating time from the start of operation of the dryer, and a calculation based on the output of the exhaust temperature detection device. A control device for a dryer comprising: a calculation control device that performs drying control by comparing a rate of change in exhaust gas temperature with a calculated value of the operating time calculated in response to the output of the operating time counting device. 2. The dryer control device according to claim 1, wherein the exhaust gas temperature detection device is configured to stop its operation during the preheating drying period. 3. A dryer comprising an exhaust temperature detection device that detects the exhaust temperature of the dryer, and a calculation control device that controls drying by comparing the rate of change in the exhaust temperature calculated based on the output of the exhaust temperature detection device with a prescribed constant. control device. 4. The dryer control device according to claim 3, wherein the exhaust temperature detection device stops the preheating drying time operation.