JPH0820393B2 - Vaporizable liquid detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention incorporates an erroneous liquid supply by incorporating it into an oil supply device such as a gas station that handles different oil types such as gasoline, light oil, and kerosene at one place. The present invention relates to a vaporizable liquid detection element used for the purpose of preventing the occurrence of the above and a vaporizable liquid discriminating apparatus using the same.

[Conventional technology]

Generally, as a detection method for oils, etc., Japanese Patent Laid-Open No. 61-142609
JP-A-60-209144, JP-A-60-209144, or JP-A-60-209144, which detects a change in capacitance of a line caused by oil permeation into a coaxial cable sensor as disclosed in JP-A-60-209144. As disclosed in Japanese Patent Laid-Open No. 60-115901, there is one that optically captures and detects a liquid such as oil.

However, all of them detect the oil as a liquid directly with a sensor, and it is impossible to determine the type of oil.

On the other hand, as the performance of diesel engines has increased, the number of passenger cars equipped with diesel engines has increased, and it is possible to determine the type of oil in a short time as a means to prevent erroneous refueling at gas stations, and to return in a short time and reuse it. There was a demand for sensor development.

[Problems to be solved by the invention]

The present invention was developed to meet these needs,
A vaporizable liquid detection element that can detect liquids such as gasoline, light oil, and kerosene in a short time despite changes in temperature, and can be reused after returning in a short time, and a vaporizable liquid discrimination device using the same Is to provide.

[Means for solving problems]

The present invention was developed to solve the above-mentioned problems of the prior art. According to the present invention, a resin material containing a conductive substance is provided between at least two electrodes, and a gas vaporized from a liquid to be detected is used. A sensing element formed by bridging a gas sensitive member that causes an impedance change upon arrival, temperature compensation means for temperature-compensating and outputting the impedance change value of the sensing element, and sensing for outputting the impedance change as a function of impedance The vaporizable liquid detection device is provided with a means and an identification means for identifying the liquid to be detected in response to the output of the detection means.

[Action]

According to the present invention, as described above, in the vaporizable liquid detection element, at least two electrodes are bridged by a gas sensitive member made of a resin material containing a conductive substance, and therefore, for example, oil vaporized from oils The molecules enter the gas sensitive member and surround the particles of the conductive substance to hinder the electrical continuity of the vaporizable liquid sensing element, so that the resistance value or impedance value between the electrodes increases. These values are compensated by the temperature compensating means by calculating the vapor pressure, which varies depending on the ambient temperature at the time of detection, from the temperature difference from the constant reference temperature and the ratio of the vapor pressure per unit temperature. Erroneous detection factors such as different impedance changes when measuring the same oil type or changes in the same impedance when measuring different oil types due to differences in vapor pressure are eliminated. This compensated impedance or its function is transmitted to the identification means, and the rate of increase of the impedance value at this time has a positive correlation with the number of molecules such as oil surrounding the particles of the conductive substance, and the vapor pressure High gasoline has a sharp increase rate compared to light oil and kerosene. The degree of vapor pressure that differs depending on the type of oil shows its own impedance value under the same temperature condition, but the impedance value transmitted to the identification means is the impedance value compensated by the compensation means as described above. Therefore, when the vaporizable liquid detection element is placed in the volatile gas atmosphere, the impedance value transmitted to the identification means is compared with a sample value previously measured at the same reference temperature as in the compensation means, or a constant value is used. The type of oil is discriminated based on whether it exceeds a threshold value or a value such as an integral value or a differential value (rate of change).

〔Example〕

FIG. 1 is a conceptual explanatory view of a vaporizable liquid detection device according to the present invention.

Explaining with reference to the drawings, the two connecting portions 3a, 3b are bridged by a gas sensitive member made of a resin material containing a conductive substance to form the sensor portion 2, and the two connecting portions 3a, 3b are connected.
Are connected to the temperature compensating means 5, the sensing means 6, and the identifying means 7 in a circuit manner by lead wires 4a and 4b, respectively.

The sensor part 2 will be described in detail. A carbon dioxide powder such as carbon black as a conductive substance is mixed with tetrafluoroethylene resin (hereinafter referred to as PTFE) powder at a ratio of 10 to 50% by weight, and a liquid lubricant is added to the mixture. Approximately 20% by weight of the mixture is kneaded and extruded at a temperature of around 327 ° C in at least one direction of about 1
Approximately 15 times stretched, a PTFE tape is attached to both sides of a gas sensitive part made of a conductive tape to protect it. Here, as the conductive tape, unfired or incompletely fired expanded porous PTFE, or unfired or incompletely fired solid PTFE can be used. Since the PTFE tape has a critical surface tension smaller than that of water and larger than that of oil, it functions to repel water and absorb vaporized oil molecules. Therefore, the sensor unit 2
When is placed in an atmosphere with oil content, the vaporized oil molecules penetrate the PTFE tape and enter the gas sensitive section, and enter into the electrical connection of the carbon black particles forming the gas sensitive section, Increase the electrical resistance (impedance) of the gas sensitive section. This increase in impedance results in an increase in impedance between the lead wires 4a and 4b that are conductively connected to both ends of the sensor unit 2. This numerical value is the atmosphere captured by the temperature detecting means (not shown) included in the temperature compensating means 5. The impedance value at the reference temperature is compensated by subtracting or adding the impedance value that increases or decreases depending on the difference Δt between the temperature and the preset reference temperature.

Next, the compensated impedance value is detected by the sensing means 6
The impedance increase rate per unit time is compared with the preset reference change for each oil type by the identification means 7 which is detected by the detection means 6 and is continuous in the circuit. The type of oil is discriminated by catching the excess of the threshold and other factors.

〔The invention's effect〕

As described above, according to the present invention, since the vaporizable liquid detection element is bridged between at least two electrodes by the gas sensitive member made of a resin material containing a conductive substance, it is volatilized from oils, for example. Since the oil molecules enter the gas sensitive member and surround the particles of the conductive substance to hinder the electrical continuity of the vaporizable liquid detection element, the impedance value between the electrodes rises. This change in impedance is detected by the measuring means. The more volatile oil vaporizes in a shorter time and raises the impedance value.Therefore, the rate of change per hour for each oil type is set in advance in the identification means, or a certain threshold value is set. It is possible to discriminate the oil type according to the setting or other factors. These values are compensated by the temperature compensating means by calculating the volatility tendency which varies depending on the ambient temperature at the time of detection from the temperature difference from a fixed reference temperature and the ratio of the volatility tendency per unit temperature. Therefore, there are no erroneous detection factors such as different impedance changes when measuring the same oil type or changes in the same impedance when measuring different oil types due to differences in volatility. Further, it is possible to change the reference temperature of the temperature compensation means by providing a switching mechanism according to the seasons of spring, summer, autumn and winter.

Further, since the detection element according to the present invention detects by vaporizing oil molecules, the detection element is taken out of the atmosphere to be detected, so that the oil component that has entered the conductive substance in the gas sensitive section is vaporized. The impedance value of the gas detecting element returns to the initial value.

That is, the present invention can detect liquid types such as gasoline, light oil, and kerosene in a short time regardless of temperature change,
Moreover, it is a vaporizable liquid discriminating device that can be restored in a short time and reused, and it can provide a means to prevent accidental refueling at gas stations etc., and made a great contribution to disaster prevention and safety assurance. .

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications within the technical idea of the present invention, such as a method for configuring a vaporizable liquid detection element, a method for compensating for temperature compensation means, a method for identifying identification means, etc. Of course it is possible.

[Brief description of drawings]

FIG. 1 is a conceptual explanatory view of a vaporizable liquid detection device according to the present invention. 2: Sensor part, 4a, 4b: Lead wire, 5: Temperature compensation means, 6: Sensing means, 7: Identification means.

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Claims (6)

[Claims] 1. A sensing element comprising a resin material containing a conductive substance between at least two electrodes, which is bridged by a gas sensitive member which causes an impedance change when a gas vaporized from a liquid to be detected arrives. Temperature compensating means for temperature-compensating and outputting the impedance change value of the sensing element, sensing means for outputting the impedance variation as a function of impedance, and identification for identifying the liquid to be sensed in response to the output of the sensing means. And a vaporizable liquid detection device. 2. The vaporizable liquid detection device according to claim 1, wherein the conductive substance of the gas sensitive member is carbon powder. 3. The vaporizable liquid detecting device according to claim 1, wherein the resin material is an unsintered tetrafluoroethylene resin molded product. 4. A vaporizable liquid detection device according to claim 1, wherein the resin material is an incompletely baked tetrafluoroethylene resin molded product. 5. The vaporizable liquid detecting device according to claim 1, wherein the resin material is an unfired stretched porous tetrafluoroethylene resin molded product. 6. The vaporizable liquid detecting device according to claim 1, wherein the resin material is an incompletely fired expanded porous tetrafluoroethylene resin material.