JPS61294337A - Oil deterioration detector - Google Patents

Abstract

PURPOSE:To surely know the exchange timing for oil by using a light source which emits light having about 400-500nm wavelength and detecting the deterioration degree of the oil from the transmittance of said light. CONSTITUTION:The light of about 400-500nm from a light emitting diode 1 is detected by a photodetector 3 and the output thereof is fed back to an automatic light dimming circuit 6 and is so regulated that the quantity of the light to be emitted by the diode 1 is made constant. The light from the diode 1 is supplied via the oil layer to a photodetector 2. The output corresponding to the deterioration degree of the oil is generated from the photodetector 2. The output is amplified by an amplifier circuit 4 and the deterioration degree of the oil is displayed by a meter 5. The absorptivity of the light from the diode 1 by the oil linearly changes and since the change rate thereof is large, the deterioration degree is exactly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deterioration detection device for oil such as edible oil and machine oil.

[Prior Art] For example, in a typical household, people used to know when to change tempura oil based on the color of the oil. In addition, the oil at fryer manufacturing shops is changed regularly.

[Problems that the invention aims to solve] If you judge when to replace oil based on the color of the oil or the number of times it has been used, or if you replace it regularly, you may end up replacing it even though it can still be used, or you may end up replacing the oil too late and the taste deteriorates. It may happen that
Appropriate replacement could not be carried out.

The present invention makes it possible to easily and reliably know when it is time to change the oil.

[Means for solving the problems] The present invention provides a light source with a wavelength of about 400 to about 5QQnm.
The degree of deterioration of the oil is detected from the transmittance of this light.

[Example] First, the relationship between the acid value, which is one of the indicators of the degree of oil deterioration, and the light transmittance will be explained.

First, when looking at changes in the acid value of oil over time, we found that when oil was continuously heated at a constant temperature, the acid value was approximately proportional to time, as shown in Figure 2. It was also revealed that the peroxide value, which is another indicator of the degree of oil deterioration, is approximately proportional to time as shown in FIG.

Therefore, while continuing to heat the oil at a constant temperature,
When we looked at the light absorption rate (100 - transmittance [%]) of the blue light emitting diode of m, we found that it was linearly proportional as shown in Figure 4.

From the above, it has become clear that the degree of oil deterioration is approximately proportional to the transmittance of blue light.

Next, the spectral characteristics of the fat at each wavelength were investigated, and the results shown in Figure 5 were obtained. In the figure, curves 11 to L7 indicate oil heating times of 0, 0.5, 1.
The transmittance is shown at 0, 2.0, 3.0, 4° for 0.5.0 hours. As is clear from this figure, when the wavelength exceeds about 500 nm (green), the change in transmittance with respect to the change in the degree of oil deterioration becomes significantly small, making detection difficult. Furthermore, if the wavelength is less than about 400 nm (blue-violet), it becomes impossible to detect if the degree of deterioration becomes large.

As is clear from this figure, light with a wavelength in the range of approximately 400 to approximately 500 nm is suitable for accurately detecting the degree of deterioration, and blue (447 nm) light is particularly suitable. .

FIG. 1 shows an example of the circuit configuration of the present invention. In the figure, 1 is a blue light emitting diode with a wavelength of 447 nm, and 2 is a light receiving element for detection, which detects the oil layer to be detected. The light from the light emitting diode is received through the light emitting diode. 3
is a light receiving element for dimming the light emitting diode 1. 4 is an amplifier circuit, and 5 is a meter that indicates the degree of oil deterioration. 6 is an automatic dimming circuit for keeping the light amount of the light emitting diode constant.

In the above configuration, the light from the light emitting diode 1 is received by the light receiving element 3, and its output is fed back to the automatic dimming circuit 6 to adjust the amount of light emitted from the light emitting diode 1 to be constant.

The light from the light emitting diode 1 is supplied to the light receiving element 2 via the oil layer, and the light receiving element 2 generates an output according to the degree of deterioration of the oil. This output is amplified by an amplifier circuit 4, and a meter 5 displays the degree of oil deterioration.

The absorption rate of light from the light emitting diode 1 due to oil changes linearly as shown in FIG. 4, and since the rate of change is large, the degree of deterioration can be detected accurately.

Note that the degree of deterioration may be displayed digitally.

[Effects of the Invention] The present invention uses a light source with a wavelength of about 400 to about 500 nm, and detects the degree of oil deterioration based on the transmittance of this light. Therefore, anyone can easily and accurately detect oil deterioration. The degree of deterioration can be detected.

[Brief explanation of drawings]

Figure 1 is an electric circuit diagram showing an embodiment of the present invention, Figure 2 is a characteristic diagram showing changes in acid value over time when tempura oil is heated at a constant temperature, and Figure 3 is a peroxide value diagram. Figure 4 is a characteristic diagram showing the change over time in the light absorption rate of a blue light emitting diode, and Figure 5 is a characteristic diagram showing the relationship between light wavelength and transmittance. . 1... Light emitting diode, 2... Light receiving element, 5...
Figure 1 Figure 2 Time [h''] 4th t4 Hours M [hrl

Claims (1)

[Claims] It is equipped with a light source that emits light with a wavelength of about 400 to about 500 nm, and a light receiving element that receives the light from the light source through a layer of oil, and detects the degree of deterioration of the oil based on the output of this light receiving element. An oil deterioration detection device characterized by: