Weighing sensor - the key force for measurement

Weighing sensor - the key force for measurement

1、 Definition and importance of weighing sensors

A weighing sensor is a device that converts the gravity or weight of an object into a measurable electrical signal output. It plays a crucial role in many fields such as modern industry, logistics, and commerce. Whether it is weighing and measuring raw materials and finished products in factories, accurately controlling the weight of goods in logistics transportation, or weighing goods in commercial transactions, weighing sensors provide reliable measurement data and are key components for achieving measurement and quality control.

2、 Working principle of weighing sensor
The common working principles of weighing sensors mainly include the following:
The principle of resistance strain gauge: utilizing the characteristic of metal resistance wire elongating and thinning under tension, resulting in an increase in resistance. When the elastic element on the weighing sensor is deformed by the gravity of an object, the resistance strain gauge attached to the elastic element also undergoes strain, resulting in a change in resistance value. By measuring the change in resistance and calculating according to the corresponding formula, the weight information of the object can be obtained.
Capacitive principle: It works based on the principle that the distance or dielectric constant between the capacitor plates changes due to the weight of the object being measured, resulting in a change in the capacitance value. For example, when an object is placed on the plates of a capacitive weighing sensor, the distance between the plates will change slightly, causing a change in capacitance. By detecting this capacitance change and converting it, the weight data of the object can be obtained.
Inductive principle: The characteristic that the inductance value of an inductive coil changes with the displacement or force of the measured object. For example, in some inductive weighing sensors, when an object applies pressure to move the armature, it causes a change in the magnetic circuit of the inductive coil, resulting in a change in the inductance value. The weight of the object is determined by measuring the change in inductance value.
3、 Composition of weighing sensors
Generally speaking, weighing sensors are mainly composed of the following parts:
Elastic element: It is one of the core components of the weighing sensor, which can produce elastic deformation under external force. The material of elastic components usually has high strength and elastic modulus, such as alloy steel, aluminum alloy, etc. Its shape design is diverse, including column, ring, beam, etc. Different shapes are suitable for different measurement scenarios and stress modes. For example, cylindrical elastic elements are commonly used to withstand larger axial pressures, while beam elastic elements are more sensitive to measuring bending forces.
Strain gauges: Strain gauges are attached to elastic components to detect the strain of the elastic components. Common strain gauges include metal strain gauges and semiconductor strain gauges. Metal strain gauges have the advantages of good stability and high accuracy, while semiconductor strain gauges have the characteristic of high sensitivity. When the elastic element deforms, the strain gauge will produce corresponding changes in resistance or other physical properties.
Measurement circuit: The main function of a measurement circuit is to convert physical signals such as resistance changes, capacitance changes, or inductance changes generated by strain gauges into electrical signals, and perform amplification, filtering, analog-to-digital conversion, and other processing for subsequent signal transmission, display, and analysis. For example, in a resistance strain type weighing sensor, a Wheatstone bridge circuit is usually used to measure the resistance change of the strain gauge.
Shell and protective device: The shell plays a role in protecting the internal components of the sensor from external environmental influences such as dust, moisture, corrosive substances, etc. The protective device may also include waterproof, dustproof cover, overload protection device, etc. The overload protection device can protect the sensor from damage when it is subjected to excessive external impact or overload, and the sensor can still work normally in harsh environments or abnormal situations.

4、 Classification of weighing sensors
There are various ways to classify weighing sensors, and the following are some common classification methods:
Classified by working principle:
Resistance strain type weighing sensor: widely used, with advantages such as high accuracy and good stability, suitable for various weighing scenarios.
Capacitive weighing sensor: It has the characteristics of high sensitivity and good dynamic response, and is commonly used in situations where high measurement accuracy and response speed are required.
Inductive weighing sensor: It has the advantages of simple structure and high reliability, and is widely used in some specific industrial environments.
Classification by measured object:
Single point weighing sensor: usually used to measure the weight or force of smaller objects, such as electronic scales and scales.
Cantilever beam type weighing sensor: suitable for measuring the weight of larger objects, such as car scales, floor scales, etc.
Wheel spoke weighing sensor: It has high resistance to eccentric load and overload, and is commonly used for weighing measurement of large lifting equipment, pressure vessels, etc.