JPH03262949A - Liquid kind detecting device - Google Patents

Abstract

PURPOSE:To detect the kind of liquid with fast response by providing a liquid kind sensor which detects the quantity of heat radiation by ambient liquid while specific temperature is reached by electric heat self-generation and a temperature sensor which detects variance in the temperature of the circumferential liquid. CONSTITUTION:The temperature detection sensor 3 which has an about 500OMEGA resistance value and the liquid kind sensor 4 which has an about 20OMEGA resistance value are held by a holder 10 in a shield wall 1. Further, a Wheatsone bridge is composed of the sensors 3 and 4 and bridge resistances 5 - 7 and its output is led out by a comparator element 8. The sensor 4 is fed with electricity for 10 seconds to generate heat by itself and stop generating heat after reaching temperature which is 10 - 20 deg.C higher than the temperature of the liquid. Then the sensor 4 varies in resistance value by heat radiation to the liquid and the bridge becomes unbalanced to cause voltage variation. This voltage variation has a constant value determined by the heat capacity of the liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid type detection device for detecting the type of liquid whose composition and properties change continuously, such as automobile fuel and petrochemical materials.

Conventional technology The use of hybrid fuels mixed with alcohol and other substances as fuel for automobiles is being considered with the goal of conserving petroleum resources and creating clean energy.

In the case of automobile fuel, as the fuel composition changes,
In order to burn under optimal combustion conditions, engine adjustments such as changing the ignition timing are required, and a device to detect the fuel type is required. Additionally, in the petrochemical industry, liquid type detection devices are also required for process control such as mixing and separation.

Conventionally, there have been detection sensors of this type of detection device that detect using physical quantities such as dielectric constant, refractive index, and heat capacity.

Problems to be Solved by the Invention When measuring using dielectric constant, if the target liquid has water absorption, the dielectric constant of water is large and the measured value fluctuates greatly, and the sensing element for dielectric constant measurement is expensive. There were issues such as the need for insulation, which resulted in a larger size.

When detecting liquid type using refractive index, the difference in refractive index is not large, an optical system is required for measurement, making the sensor complex and large, and the measurement system, signal output circuit, and signal processing circuit are complex and expensive. There was an issue of becoming.

Further, when measuring using heat capacity, a large amount of heat is required to raise the temperature of the sensor because the heat capacity of the detection sensor itself is large. As a result, the thermal response is poor, and the temperature of the liquid surrounding the sensor increases due to the heat generated by the sensor.
There was a problem in that it was difficult to accurately measure heat capacity.

The present invention solves these problems, and aims to provide a liquid type detection device that has excellent responsiveness, accuracy, and good reproducibility.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a liquid type sensor that detects the amount of heat dissipated by the surrounding liquid when the temperature reaches a predetermined temperature due to self-heating due to energization, and a liquid type sensor that detects changes in the temperature of the surrounding liquid. The configuration includes a temperature sensor for detection.

Function In this configuration, when the liquid type detection sensor that is self-heated by energization is left in the liquid, heat is released into the liquid.
The liquid type detection sensor is cooled. At this time, the cooling rate changes according to the heat capacity of the liquid, and the type of liquid is determined by detecting the amount of change in this cooling rate.

Furthermore, the temperature sensor used in combination has the function of avoiding the influence of fluctuations in liquid temperature on measurements.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

As shown in FIGS. 1 and 2, the shielding wall 1 has a height of 25 mm provided near the bottom of a liquid container 12 filled with liquid.
, is formed into a cylindrical shape with a diameter of 405 mm and has an opening 2 directly above it. Resistance value approximately 500Ω inward of shielding wall 1
A temperature detection sensor 3 and a liquid type detection sensor 4 having a resistance of about 20Ω are installed, and a circuit box 13 is installed outside the holder 10 and liquid container 12 for holding these sensors 3 and 4.

FIG. 3 is a circuit configuration diagram of an example of the present invention, in which a temperature detection sensor 3, a liquid type detection sensor 4, bridge resistors 5, 6, .
7 forms a Wheatstone bridge, the output of which is taken out by a comparator element 8. 9 in the figure indicates an output terminal. Further, the liquid to be measured 11 is indicated by diagonal lines.

Here, the liquid type detection sensor 4 is energized for 10 seconds to generate self-heating, and after being heated to a temperature 10 to 20° C. higher than the liquid, self-heating is stopped. The resistance value of the liquid type detection sensor 4 changes due to heat radiation to the liquid, and the balance of the constituent bridge is disrupted, causing a voltage change. The voltage change takes a constant value determined by the heat capacity of the liquid.

FIG. 4 shows an example of the temperature detection sensor 3 and the liquid type detection sensor 4, which are mounted on a 5 x 2 m alumina substrate 14.
A temperature sensing film 15 made of a platinum thin film with a thickness of 5 μm is provided, and extraction electrodes 16a made of 1×2 palladium are provided at both ends of the film.
and 16b. These lead-out electrodes 16a and 16b are connected to lead-out terminals 17a and 17 made of platinum wire with a thickness of 0.5 mm.
b is attached by welding. The electrical resistance value of the temperature detection film 15 of the liquid type detection sensor 4 is approximately 20Ω (20
℃), and the temperature coefficient of resistance is 3850 ppm/℃ (0/10
0°C).

Further, the electrical resistance value of the temperature detection sensor 3 is the same as the liquid type detection sensor 4 except that it is approximately 500Ω. At a liquid temperature of 28°C, the surface temperature of the liquid type detection sensor 4 became 20°C higher than the liquid temperature after 10 seconds of electrical heating. Heat capacity 0.
When comparing liquid A with a heat capacity of 47 and liquid B with a heat capacity of 0.37, values of 2.41 V and 1.93 V were confirmed in the voltage output after heating was stopped.

Note that the temperature detection sensor 3 and the liquid type detection sensor 4
It is also possible to use one sensor for both.

Effects of the Invention As is clear from the above description of the embodiments, according to the present invention, the type of liquid can be electrically detected with a quick response based on the difference in heat capacity. Furthermore, since it is possible to detect small differences in heat capacity, it is also possible to measure cases where the mixing ratio of a plurality of liquids changes continuously. In addition, since the amount of heat generated by the liquid type detection sensor is small compared to the heat capacity of the liquid, there is no danger of ignition even when used with flammable liquids, and it does not change the properties of the liquid, so it can be used for continuous measurement over long periods of time. It has no effect. Furthermore, since the liquid type detection sensor is small and has a small heat capacity, its response time is also short. In this way, it is possible to easily manufacture a liquid type detection device that has excellent responsiveness, can measure accurately and reproducibly, and is resistant to mechanical shock at a low cost.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of the liquid type detection device of the present invention, FIG. 2 is a sectional view of the main part 7164, FIG. 3 is a circuit configuration diagram, and FIG. 4 is a perspective view of the sensor. It is a diagram. 1... Shielding wall, 3... Liquid temperature sensor, 4... Liquid type sensor, 10... Holder, 11... Measured object liquid.

Claims (3)

[Claims] (1) A liquid type detection device that includes a liquid type sensor that detects the amount of heat released by the surrounding liquid when it reaches a predetermined temperature due to self-heating due to energization, and a temperature sensor that detects changes in the temperature of the surrounding liquid. (2) The liquid type detection device according to claim 1, wherein the liquid type sensor and the temperature sensor are integrated. (3) A liquid type detection device comprising a Wheatstone bridge including a liquid type sensor and a temperature sensor, respectively, and configured to obtain a measurement output from the Wheatstone bridge.