Sensor designed based on metal expansion principle

The metal will produce a corresponding extension after the ambient temperature changes, so the sensor can convert the signal of this reaction in different ways.

Bimetallic chip sensor

The bimetallic sheet is composed of two pieces of metal with different expansion coefficients. With the change of temperature, the expansion degree of material a is higher than that of another metal, causing the metal sheet to bend. The curvature of the bend can be converted into an output signal.

Bimetallic sensor rod and bimetallic tube

As the temperature rises, the length of the metal tube (material a) increases, while the length of the non expanding steel rod (metal b) does not increase, so that the linear expansion of the metal tube can be transmitted due to the change of position. In turn, this linear expansion can be converted into an output signal.

Sensor designed for deformation curve of liquid and gas

When the temperature changes, the volume of liquid and gas will also change accordingly.

Various types of structures can convert this expansion change into position change, resulting in position change output (potentiometer, inductive deviation, baffle, etc.).

Resistance sensing

As the temperature of metal changes, its resistance value also changes.

For different metals, the resistance value changes differently with each degree of temperature change, and the resistance value can be directly used as the output signal.

There are two types of resistance changes

Positive temperature coefficient

Temperature rise = resistance increase

Temperature decrease = resistance decrease

Negative temperature coefficient

Temperature rise = resistance decrease

Temperature decrease = resistance increase

Thermocouple sensing

The thermocouple consists of two metal wires of different materials, which are welded together at the end. Then measure the ambient temperature of the unheated part, and you can accurately know the temperature of the heating point. Because it must have two kinds of conductors of different materials, it is called thermocouple. Thermocouples made of different materials are used in different temperature ranges, and their sensitivity is also different. The sensitivity of thermocouple refers to the change of output potential difference when the hot spot temperature changes by 1 ℃. For most thermocouples supported by metal materials, this value is about 5 ~ 40 microvolt / ℃.

Because the sensitivity of thermocouple temperature sensor has nothing to do with the thickness of material, it can also be made of very fine material. Due to the good ductility of the metal materials used to make thermocouples, this fine temperature measuring element has a very high response speed and can measure the process of rapid change.