JPH0411240B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dehydration control device that controls a dehydration operation using a detector that optically detects liquid discharged during the dehydration operation.

(Prior art and its problems) Recently, in dehydration control equipment, the liquid discharged during dehydration operation (dehydration liquid) is optically detected by a detector consisting of a combination of a light emitting element and a light receiving element. Various devices have been proposed that determine the end of dehydration based on the output signal of the device and automatically stop the dehydration operation. A configuration is adopted in which the detection is performed through a detection window.

However, with such a configuration, when the amount of liquid discharged decreases and becomes extremely small, there is a possibility that the liquid cannot be detected. In other words, when the amount of liquid is very small, the liquid becomes droplets and flows down the drain pipe wall. At this time, if the water droplets flow down through areas other than the detection window, the water droplets will enter the light path of the detector. Therefore, the detector cannot detect the water droplets.

As described above, with the conventional configuration, it was not possible to reliably detect a very small amount of liquid, resulting in low accuracy in controlling the dehydration operation.

(Object of the Invention) The present invention has been made in view of the above points, and it is an object of the present invention to provide a dehydration control device that can reliably detect even a very small amount of liquid and has high control accuracy.

(Structure of the Invention) The present invention achieves the intended purpose by providing a guide part in the drainage pipe that guides the liquid flowing down the pipe wall toward the detection window. be.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a detection part of a detector in an embodiment of the present invention. 11 is a light emitting element, 2
is a light-receiving element that constitutes a detector together with the light-emitting element 1; 3 is a drain pipe for discharging liquid (dehydrated liquid) from the dehydration tank to the outside of the machine; 4 is provided facing the wall of the drain pipe 3; A pair of transparent detection windows, 5 is an eave-shaped guide part provided upstream of the detection window 4 in the drain pipe 3, and the guide part 5 is located at a position shifted from the detection window 4 in the circumferential direction. The liquid flowing down along the wall of the drain pipe 3 is guided to the detection window 4 side. With the above configuration, even when a very small amount of liquid is discharged and flows down in the form of water droplets, the liquid flows reliably through the detection window 4 due to the guiding action of the guide portion 5, and is reliably detected by the detector. I can do it.

Here, using as an example the dewatering operation of 3 kg of loose cloth in a fully automatic washing machine, changes in the flow of liquid in the detection section will be explained with reference to FIG. Now, when dehydration starts (0 seconds), the rotation speed of the motor will gradually increase, and the dehydrated liquid discharged from the dehydration tank will be led to the detection unit through the drain pipe 3, and the dehydrated liquid will be discharged in about 10 seconds. As the amount increases, a turbulent flow containing air occurs as shown in FIG. After about 15 seconds, the amount of dehydrated liquid decreases and becomes stable, so that the dehydrated liquid flows in a laminar flow along the detection window 4 as shown in Figure 2b, and the diffused reflection of light is reduced. This improves the light transmittance of the detector. Furthermore, after about 30 seconds, the amount of dehydrated liquid decreases significantly, and as shown in Fig. 2c, it becomes water droplets, which appear on the detection window 4.
The light is refracted by the lens effect of the water droplets and does not travel straight, reducing the light transmittance of the detector. In addition, in FIG. 2, the direction in which the light travels is indicated by an arrow.

Figure 3 is a diagram showing the changes in the output voltage of the detector and the dehydration rate during the dehydration operation described above.As can be seen from this figure, the point 30 seconds after the start of dehydration is the point where the change in the dehydration rate changes from rapid to slow. matches. Therefore, by detecting the second peak of the change in light transmittance of the detector (point A in Figure 3), it is possible to detect the time from the start of dehydration until the change in dehydration rate changes from rapid to slow. can. Note that experiments have shown that it is necessary to add a certain amount of time (for example, 3 minutes) to this time in order to actually narrow down the limit. The dehydration rate is determined by the formula below. However, the weight of the cloth is the weight of the cloth that has dried naturally.

Dehydration rate = 100 − {Weight of cloth containing water − Weight of cloth / Weight of cloth × 100
} (%) Also, if you want to make it half-wrapped (to make clothes less likely to wrinkle), instead of actually squeezing it all the way,
The time when the dehydration rate changes from rapid to slow (in the example
Experiments have shown that dehydration can be completed in 30 seconds). Therefore, by detecting the second peak of the change in permeability (the point at which the change in dehydration rate changes from rapid to slow), determining the end time of dehydration based on the detected time, and controlling the dehydration operation, Appropriate dehydration can be performed.

(Effects of the Invention) As described above, according to the present invention, it is possible to reliably detect even a very small amount of liquid and to accurately obtain a standard that serves as a guide for controlling the end of dehydration, thereby increasing the accuracy of dehydration control. I can do it.

[Brief explanation of drawings]

Figures 1a and 1b are horizontal and vertical sectional views showing the structure of the detection part of a detector in an embodiment of the present invention, and Figure 2a,
b and c are diagrams for explaining the flow of liquid in the same detection section, and FIG. 3 is a diagram showing temporal changes in the output voltage and dehydration rate of the same detector. DESCRIPTION OF SYMBOLS 1... Light emitting element, 2... Light receiving element, 3... Drainage pipe, 4... Detection part, 5... Guide part.

Claims (1)

[Scope of Claims] 1. A detector that includes a pair of detection windows facing each other on the wall of a drainage pipe for liquid discharged during a dehydration operation, and optically detects the liquid in the drainage pipe through the detection windows. and controls the dewatering operation based on the output signal of this detector, wherein a guide part is provided in the drainage pipe to guide the liquid flowing down along the wall of the pipe to the detection window, A dehydration control device that controls dehydration operation based on the second peak of the change in light transmittance detected by the device.