Negative temperature coefficient thermistor, also known as NTC thermistor, is a kind of sensor resistor whose resistance value decreases with the increase of temperature. Widely used in various Electronic components, such as temperature sensors, resettable fuses and self-adjusting heaters.

Negative temperature coefficient thermistor, also known as NTC thermistor, is a kind of sensor resistor whose resistance value decreases with the increase of temperature. Widely used in various electronic components, such as temperature sensors, resettable fuses and self-adjusting heaters.

1. Electrothermal coolant temperature gauge and bimetallic sensor

(1) Structure

The basic structure of the electrothermal coolant temperature gauge and the bimetallic sensor is shown in Figure 1.

Analyze the main components and principles of thermistor sensors

Figure 1 Electrothermal coolant temperature gauge and bimetallic sensor

(2) Principle

When the ignition switch is turned ON, the current flows through the heating coil, the bimetal 4 is heated and deformed to separate the contacts and cut off the circuit; then the bimetal cools and straightens, the contacts are closed again, and the circuit is turned on again, and so on. A pulse current is formed in the circuit.

When the coolant temperature is low, the deformation of the bimetal sheet 2 is small, the contact pressure is large, the closing time is long, the opening time is short, and the average value of the current in the circuit is large, the current flows through the heating coil of the indicator, and the bimetal of the indicator The deformation of the sheet 9 is large, the deflection angle of the pointer is large, and the pointer points to a low temperature; on the contrary, when the water temperature is high, the bimetal sheet 2 in the sensor warps and deforms greatly, the contact pressure is small, the closing time is short, the opening time is long, and the current in the circuit The average value is small, the deformation of the bimetal sheet 9 of the indicator is small, the deflection angle of the pointer is small, and it points to a high temperature.

2. Electrothermal coolant temperature gauge and thermistor sensor

(1) Structure

Its basic structure is shown in Figure 2. The main element of the thermistor sensor is a negative temperature coefficient thermistor.

(2) Principle

When the ignition switch is ON, the current flows through the positive electrode of the battery → ignition switch → power regulator → heating coil 7 of bimetal 6 of the thermometer → sensor terminal 12 → thermistor 14 → sensor shell 15 → ground → battery negative electrode.

Analyze the main components and principles of thermistor sensors

Figure 2 Electrothermal coolant temperature gauge, thermistor sensor and voltage regulator

When the temperature of the engine coolant is low, the resistance of the thermistor of the sensor is large, the average value of the current in the circuit is small, the bending deformation of the bimetal sheet of the thermometer is small, and the pointer points to the low temperature; on the contrary, when the temperature of the coolant increases, the The resistance of the thermistor is small, the average value of the current in the circuit is large, the bimetallic sheet of the thermometer has a large bending deformation, and the pointer points to a high temperature.

The Links:   SP14Q003-A AND10C209A-HB