Torque sensor principle - Solutions - Huaqiang Electronic Network

Crystal oscillator

Quartz Oscillator 3225 20M OSC

The torque sensor has emerged and has been used in various industries in a short period of time, becoming an indispensable part of the sensor family.

One feature

1. It can measure both static torque and rotational torque;

2. Both static torque and dynamic torque can be measured;

3. High detection accuracy, good stability; strong anti-interference;

4. Small size, light weight, various mounting structures, easy to install and use;

5. Continuously measure the forward and reverse torque without repeated zero adjustment;

6. There are no wear parts such as conductive rings, which can be operated at high speed for a long time;

7. The sensor output high frequency signal can be directly sent to the computer for processing;

8. Measuring elastomer strength can withstand 100% overload.

Two measurement principle

The special torsion strain gauge is glued to the elastic shaft to be tested and formed into a strain bridge, and the electrical signal of the elastic shaft is measured by supplying power to the strain bridge. After the strain signal is amplified, it undergoes voltage/frequency conversion to become a frequency signal proportional to the twist. The energy input and signal output of the system are carried out by two special ring-type transformers with gaps, thus achieving contactless energy and signal transmission functions. (The inside of the dotted line is the rotating part)

Three sensor principle structure

A special torque measuring piece is attached to a special elastic shaft and constitutes a variable bridge, which is a basic torque sensor; fixed on the shaft: (1) secondary coil of energy toroidal transformer, (2) signal toroidal transformer primary Coil, (3) printed circuit board on the shaft, the circuit board includes a rectified stable power supply, an instrumentation amplifier circuit, a V/F conversion circuit, and a signal output circuit.

Four working processes

Providing ±15V power to the sensor, the crystal oscillator in the excitation circuit generates a 400Hz square wave, and the AC excitation power source is generated by the TDA2030 power amplifier, and is transmitted from the stationary primary coil to the rotating secondary coil through the energy toroidal transformer T1. The AC power supply obtains a ±5V DC power supply through the rectifying and filtering circuit on the shaft. The power supply is used as the operating power supply of the operational amplifier AD822. The high-precision regulated power supply consisting of the reference power supply AD589 and the dual op amp AD822 generates a precision DC of ±4.5V. Power supply, which acts as both a bridge power supply and an operating power source for amplifiers and V/F converters. When the elastic shaft is twisted, the strain signal of the mV level obtained by the strain bridge is amplified by the instrumentation amplifier AD620 into a strong signal of 1.5v±1v, and then converted into a frequency signal by the V/F converter LM131, and passed through the signal toroidal transformer T2. It is transmitted from the rotating primary coil to the stationary secondary coil, and then filtered and shaped by the signal processing circuit on the sensor casing to obtain a frequency signal proportional to the torque received by the elastic bearing. The signal is TTL level and can be supplied to The dedicated secondary meter or frequency meter display can also be sent directly to the computer for processing. Because there is only a few millimeters of clearance between the dynamic and static rings of the resolver, and the upper part of the sensor shaft is sealed inside the metal casing to form an effective shielding, it has strong anti-interference ability.

Five applications

1. Detect the output torque and power of rotating power equipment such as generators, motors, and internal combustion engines.

2. Detect the load torque and input power of reducer, fan, pump, mixer, winch, propeller, drilling machinery and other equipment.

3. Detect the torque of various machining centers and automatic machine tools.

4. Torque and efficiency transmitted by various rotating power equipment systems;

5. The speed and axial force can be detected while detecting the torque.

6. Can be used to manufacture viscometer, electric (pneumatic, hydraulic) torque wrench.