Why can not the sensor of a bimetallic thermometer be made hollow?

How a bimetal thermometer works

The sensor of a bimetal thermometer consists of two metal sheets with different coefficients of expansion. When the temperature changes, the two metals expand differently, causing the metal sheet to bend, which causes the pointer to deflect to indicate the temperature. This design relies on the integrity and mechanical strength of the metal sheet, and the hollow structure can significantly weaken the mechanical properties of the metal sheet, resulting in the sensor not responding accurately to temperature changes.

Structural features of bimetal thermometer

The core component of a bimetal thermometer is the temperature sensing element, which is usually composed of two metal sheets with different coefficients of thermal expansion. When the outside temperature changes, due to the different expansion coefficients of the two metals, bending deformation will occur, and this deformation directly reflects the change in temperature.The function of the transmission mechanism is to convert the small deformation of the temperature sensing element into the displacement of the pointer on the dial. The clever design ensures that the movement of the hands is proportional to the change in temperature, resulting in an accurate temperature indication.The indicator is usually in the form of a pointer and a dial, the displacement of the pointer corresponds to the temperature value on the dial, and the user can read the current temperature directly from the dial.The housing is used to protect the thermometer internal temperature sensing element and transmission mechanism, while ensuring that the user can clearly observe the indicator's readings. The housing is usually made of high-temperature, corrosion-resistant materials to ensure that the thermometer can work properly in a variety of harsh environments.

It is precisely because of the working principle and structural characteristics of the bimetal thermometer, and also to ensure the accuracy of the measurement, that the sensor of the bimetal thermometer must be designed as a solid structure.