Since its emergence, torque sensors have been applied to various industries in a short period of time, becoming an indispensable type of sensor.
1. Features
1. It can measure both static torque and rotational torque;
2. It can measure both static torque and dynamic torque;
3. High detection accuracy, good stability, and strong anti-interference capability;
4. Small size, light weight, multiple installation structures, easy to install and use;
5. Continuous measurement of forward and reverse torque is possible without repeated zeroing;
6. It has no wear parts such as conductive rings, and can operate at high speeds for extended periods;
7. The high-level frequency signal output by the sensor can be directly sent to a computer for processing;
8. The measured elastomer strength is high and can withstand 100% overload.
II: Measurement Principle
Specialized torsional strain gauges are adhered to the elastic shaft under test using strain gauge adhesive to form a strain bridge. Power is supplied to the strain bridge to measure the electrical signal of the elastic shaft under torsion. This strain signal is amplified and converted into a frequency signal proportional to the torsional strain through a voltage-to-frequency converter. The system's energy input and signal output are handled by two sets of special toroidal transformers with gaps, thus achieving contactless energy and signal transmission. (The area within the dashed line represents the rotating part.)
III: Sensor Principle and Structure
A special torsion measuring plate is attached to a specially made elastic shaft to form a variable bridge, which is the basic torque sensor; the shaft is fixed with: (1) the secondary coil of the energy ring transformer, (2) the primary coil of the signal ring transformer, and (3) the printed circuit board on the shaft, which includes a rectified stable power supply, an instrument amplification circuit, a V/F conversion circuit and a signal output circuit.
IV: Work Process
A ±15V power supply is provided to the sensor. The crystal oscillator in the excitation circuit generates a 400Hz square wave, which is then amplified by the TDA2030 power amplifier to produce an AC excitation power supply. This AC power supply is transferred from the stationary primary coil to the rotating secondary coil through the energy toroidal transformer T1. The resulting AC power supply is then rectified and filtered by the shaft to obtain a ±5V DC power supply, which serves as the operating power supply for the operational amplifier AD822. A high-precision regulated power supply composed of the reference power supply AD589 and the dual operational amplifier AD822 generates a ±4.5V precision DC power supply, which serves as both the bridge power supply and the operating power supply for the amplifier and V/F converter. When the elastic shaft is subjected to torsion, the strain signal in the mV range detected by the strain bridge is amplified into a strong signal of 1.5V ± 1V by the AD620 instrumentation amplifier, and then converted into a frequency signal by the LM131 V/F converter. This signal is transmitted from the rotating primary coil to the stationary secondary coil through the signal toroidal transformer T2. After filtering and shaping by the signal processing circuit on the sensor housing, a frequency signal proportional to the torque on the elastic bearing is obtained. This signal is TTL level and can be provided to a dedicated secondary instrument or frequency meter for display or directly sent to a computer for processing. Because the gap between the moving and stationary rings of the rotary transformer is only a few tenths of a millimeter, and the upper part of the sensor shaft is sealed within a metal housing, forming effective shielding, it has a strong anti-interference capability.
5. Scope of Application
1. Detect the output torque and power of rotating power equipment such as generators, electric motors, and internal combustion engines.
2. Test the load torque and input power of equipment such as speed reducers, fans, pumps, mixers, winches, propellers, and drilling machinery.
3. Detect the torque during the operation of various machining centers and automatic machine tools.
4. The torque and efficiency transmitted by various rotating power equipment systems;
5. It can detect rotational speed and axial force simultaneously with torque.
6. It can be used to manufacture viscometers and electric (pneumatic, hydraulic) torque wrenches.
