JPH03208302A - Element for oil level detection device - Google Patents

Abstract

PURPOSE:To enable a title device to be operative over a wide temperature range in a high temperature region and lower heating temperature of the device by combining a negative temperature coefficient thermistor element and fixed resistor in parallel to each other. CONSTITUTION:Two lead wires 9 are connected to an electrode surface of a negative temperature coefficient thermistor element 5 including an electrode 6 formed thereon and an electrode 6 formed thereon and an electrode surface of a fixed resistor 7 including an electrode 8 formed thereon, and the whole structure is coated with a glass material 11. More specifically, a title device is governed by the resistance of the fixed resistor 7 in a low temperature region and by a resistance-temperature characteristic of the negative temperature coefficient thermistor 5 in a high temperature region. Hereby, the device is made operable in a temperature variation range of oil of automobiles upon their travelling and heating temperature of the device can be limited to a lower one for its stable characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used as an element for detecting the level of liquid such as engine oil in automobile equipment, and can be used in a temperature range of approximately 50 to 140°C, and is a low-cost oil. The present invention relates to an element for a liquid level detection device.

Conventional technology Conventionally, as a low-cost type of liquid level detection device that detects the position of liquid level, a thermistor is used that applies a voltage within a certain range to a circuit in which a light bulb as a warning light is connected in series with a thermistor element for liquid level detection. A device is known that turns on or off a light bulb by controlling the amount of current flowing through a circuit by utilizing the difference in heat dissipation constant between the air and liquid of the element. Here, the liquid level detection thermistor element used in this type of device has a configuration as shown in FIG. In FIG. 2, reference numeral 1 denotes a cylindrical or prismatic thermistor element with electrodes 2 formed at both ends, and two lead wires 3 with thermistor holders are press-fitted into the electrodes 2 at both ends of the thermistor body 10. After that, it is coated with glass material 4 or the like.

Problems to be Solved by the Invention This conventional configuration has the following problems.

Devices such as those described in the prior art are known as low-cost liquid level detection devices for detecting the liquid level position. The operating temperature range is about ~60℃, which is a low temperature range.Because the operating temperature range is narrow, if a material with the resistance-temperature characteristics of a general thermistor material is used in the design calculation, the thermistor can be used. Even if an element using this material is used alone, it can operate within the above operating temperature range. However, the temperature of automobile engine oil and the like is thought to reach 60 to 140 degrees Celsius while the vehicle is running, so its operating temperature is higher and wider than the above-mentioned gasoline remaining amount warning device. In other words, even if design calculations are performed taking such conditions into consideration, it is difficult to select a thermistor material with characteristics that operate within the above temperature range from the resistance-temperature characteristics of general thermistor materials.

Even if the thermistor can be operated by itself, the heat generation temperature of the element exceeds 450° C. at maximum, which causes a change in the resistance value of the Saminuta element, making it unsustainable for long-term use. Here, an example of design calculation results under the following usage conditions is shown below.

Conditions Operating temperature range 60~140°C Bulb rating 12V 3.4W Applied voltage 12~15V Bulb lighting current 135111 or more Bulb extinguishing current 60mm or less Thermistor element heat dissipation constant Medium 2.51m W/'C in oil
10! IIW/°C Thermistor element required resistance - Temperature characteristics 600C 3640Ω or less 207℃ 2310 or more 340'C 49Q or less Maximum heat generation temperature of thermistor element 490'C (140°C in air) In this way, - Resistance of the thermistor material used in boats - In terms of temperature characteristics, it is difficult to obtain the required resistance-temperature characteristics described above, and the maximum temperature at which the thermistor element generates heat is 49
When the temperature reaches 0°C, the resistance value of the thermistor element changes and cannot withstand long-term use.

The present invention solves these problems, and by combining a thermistor and a constant resistor, it can operate in a temperature range of 50 to 140 degrees Celsius, and by keeping the maximum heat generation temperature of the element low, it can be used for a long time. The object of the present invention is to provide a durable, low-cost type element for an oil level detection device.

Means for Solving the Problems Therefore, in order to solve the above-mentioned problems, the technical means of the present invention is to provide electrodes on both sides of a chip-shaped negative characteristic thermistor element body having electrodes formed on both opposite sides, and electrodes on both opposite sides. Two lead wires are connected to the electrode surfaces on both sides of a chip-shaped constant resistor formed with a constant resistor, and the entire lead wire except for a part is coated with a glass material.

Effects According to the configuration of the present invention, in the low temperature region, the resistance value of the constant resistor governs, and in the high temperature region, the resistance value calculated by the above-mentioned design calculation is governed by the resistance-temperature characteristic of the negative characteristic thermistor. By using a negative characteristic thermistor that has a characteristic within the resistance-temperature characteristic range and has a high B constant, it is possible to keep the maximum heat generation temperature of the element for the oil level detection device low. In other words, it is possible to provide an element for an oil level detection device that can be used in a temperature range of about 60 to 14 degrees Celsius and guarantees stable reliability.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to FIG.

FIG. 1 is a sectional view of an element for an oil level detection device according to an actual flow example of the present invention. In the figure, a chip-shaped negative characteristic thermistor element 6 has electrodes 6 made of platinum, silver, or silver-palladium alloy formed on both opposing surfaces, and electrodes 6 made of platinum, silver, or silver-palladium alloy are formed on both opposing surfaces. A conductive wire made of platinum, silver, or a silver-palladium alloy is connected to two lead wires 9 having a low coefficient of thermal expansion, such as SUS430, on both surfaces of the chip-like constant resistor 70, which has an electrode 8 formed thereon. The wires are connected by applying and baking a 1° adhesive paste, and the entire lead wire 9 except for a portion thereof is coated with a glass material 11. Here, the electrical characteristic values of the negative characteristic thermistor element 5 and the constant resistance element 7 used in this example are shown below.

Negative characteristic thermistor element 26℃ 500 Ω B constant (2615o) 5500 constant resistor 3.6 Ω Figure 2 shows the resistance temperature characteristics when negative characteristic thermistor element 5 and constant resistor 7 are combined in parallel. Shown below.

Data obtained from experiments conducted by incorporating the element for the oil level detection device in this example into the circuit shown in FIG. 3 are shown below.

Operating temperature range: 50 to 140'C Bulb rating: 12V 3.4W Applied voltage: 12 to 15V Light bulb lighting current: 135 mÅ or more Bulb extinguishing current: 60 mA or less Actual data Maximum heat generation temperature of oil level detection device element: 3so'C (
According to this embodiment as described above, by combining the negative characteristic thermistor element 5 and the constant resistance element 7 in parallel, it is possible to achieve a wide temperature range in the high temperature region (SO to 140'C) and Voltage (12
~1 sV), and
The heat generation temperature of the element can be kept low.

Effects of the Invention As described above, according to the present invention, by combining a negative characteristic thermistor element and a constant resistance element in parallel, the temperature fluctuation range of oil (SO to 140°C) and voltage fluctuation during driving of a car can be suppressed. It is possible to operate within the range (12 to 16 V), and the heat generation temperature of the element can be suppressed to a maximum of around 350°C, making it possible to guarantee stable characteristics even under harsh usage conditions. .

[Brief explanation of drawings]

Fig. 1 is a sectional view of an element for an oil level detection device according to an example of the present invention, Fig. 2 is a resistance temperature characteristic diagram of the same, Fig. 3 is an electrical circuit diagram showing an example of the use of the element, FIG. 4 is a sectional view showing a thermistor element used in a conventional liquid level detection device. 5... Negative characteristic thermistor element, 6... Electrode,
7... Constant resistor, 8... Electrode, 9...
・Lead wire, 10... Conductive paste, 11 ・
...Glass material.

Claims (2)

[Claims] (1) Two lead wires on the electrode surfaces on both sides of a chip-shaped negative characteristic thermistor element body with electrodes formed on both opposing surfaces, and on the electrode surfaces on both sides of a chip-shaped constant resistor body with electrodes formed on both opposing surfaces. An element for an oil level detection device, characterized in that the entire lead wire except for a part of the lead wire is coated with a glass material. (2) An element for an oil level detection device according to claim 1, which uses SUS430 material as the lead wire material.