Torque sensors are very important in industrial manufacturing. The following is a detailed introduction from the aspects of principle, types, applications, and installation.
What is Torque?
Torque is an indicator of the ability to measure the size of mechanical output force. It is the core parameter of the external characteristics of power machinery. It is the key to judging the performance of rotating machinery.
Its measurement needs are wide. Torque is a couple or moment. It can cause mechanical parts to produce a rotation effect accompanied by torsional deformation. Its symbol is usually represented by T.
In engineering parlance, torque is the product of force and distance, measured in units like Newton-meters (Nm) or pound-feet (lb-ft).
Types and Characteristics of torque mainly include:
(a) Static torque:
The shaft under its action does not rotate, and the torque value remains constant. For example, when a crane is lifting a heavy object and remains stationary. The torque borne by the shaft in the transmission system can be regarded as static torque.
(b) Constant torque:
The torque value remains constant during the rotation of the shaft. This type of torque is commonly seen in the output of equipment. such as motors and blowers, under stable working conditions.
(c) Slow-varying torque
It refers to torque whose value changes slowly over time.
During the measurement process. Due to its slow change rate, it can be approximately considered that its torque value is constant. It is usually characterized by the torque value at a certain moment and its corresponding speed. For example, the working torque of a mixer that runs for a long time can be regarded as a slow-varying torque.
(d) Pulsating torque:
The average value remains constant, but the instantaneous value will show a small pulsating change. The characterization parameters of this type of torque include the mean value, the pulsating amplitude ΔT, and the pulse frequency f. The torque of many rotating machines includes internal combustion engines and water pumps.
What is a Torque Sensor?
Torque sensor, also known as torque transducer, torque meter, or torque transmitter. It is a precision instrument used to measure the torsional torque on rotating or non-rotating mechanical parts. It converts physical torque into electrical signals.
Torque sensors also have other functions. It can also record other measured variables. This is optional. The most important parameter is the speed. It can be measured by a light-transmitting slotted disc on the rotor.
Another important characteristic that many users are interested in is power. Power can be calculated by multiplying torque by speed. In addition, many torque sensors have a built-in temperature sensor. It can tell us the operating temperature of the sensor.
Torque Sensor Signal Transmission:
Traditional:
Conductive slip ring (easy to wear, short life, poor performance at low speed).
Improved:
Wireless telemetry (convert strain signal into frequency signal, transmit by radio). Magnetoelectric conversion. fiber optic transmission, etc.
Torque Sensor Working Principle
Strain electrical measurement technology (mainstream method):
Strain gauges are pasted on the elastic shaft. When the shaft is subjected to torque, it will produce a small deformation. The change in resistance of the strain gauge is converted into an electrical signal. The signal transmission problem between the rotating body and the stationary body needs to be solved.
Non-contact technology (such as magnetoelectric, fiber optic, photoelectric):
Through changes in magnetic induction intensity, optical phase difference or electromagnetic induction, etc. It achieves contactless signal transmission and avoids wear.
Torque Sensor Types and Features
1. Dynamic and static torque sensors:
Dynamic torque sensor: Measures torque changes during rotation, often used for real-time monitoring (such as engine output torque). It needs to have a high-frequency response and anti-interference capabilities.
Static torque sensor: Measures torque in a stationary or slowly rotating state, used for calibration or laboratory testing.
2. Non-contact and contact type:
Non-contact type (advantages): long life, high reliability, anti-interference, and easy installation. Typical examples include magnetoelectric type and fiber optic type.
Contact type (traditional): relies on conductive slip rings or strain gauges, which are easy to wear, but the technology is mature and the cost is low.
3. Subdivided types:
Torsion angle phase difference type:
The torque is calculated by measuring the phase difference between two sets of gear sensors.
Strain gauge sensor: detects elastic shaft deformation through resistance strain gauges.
Magnetostrictive sensor: uses the expansion and contraction properties of materials under magnetic fields.
Fiber optic type: measures torque through phase changes of optical signals.
Wireless surface acoustic wave type: uses the propagation characteristics of sound waves.
Dynamic Torque Sensor VS Static Torque Sensor
Static torque sensors measure static or steady-state torque. such as bridges, buildings, heavy machinery, etc.
The working principle of static torque sensors is based on the principle of resistance strain. The torque is calculated by measuring the deformation of the strain gauge. When the torque acts on the sensor, the strain gauge will deform. The deformation changes its resistance value. By measuring and processing the resistance value, the magnitude and direction of the torque can be calculated. Static torque sensors usually consist of a pair of sensors, one for detecting stress and the other for detecting strain.
Dynamic torque sensors are mainly used to measure the dynamic torque of rotating machinery. Such as motors, engines, turbines, etc.
The working principle is based on the principle of electromagnetic induction. Torque is calculated by measuring the change of the magnetic field on the rotating shaft. When the torque acts on the sensor, the teeth or magnets on the shaft are deformed. The deformation changes the magnetic resistance of the magnetic circuit. Cause the magnetic lines of force to change.
These changing magnetic lines of force will generate an induced electromotive force. The magnitude of which is proportional to the applied torque. The sensor is equipped with an induction coil inside. The torque is applied to the rotating shaft. It can be calculated by measuring the magnitude of the induced electromotive force.
Torque Sensor Applications
Automotive Industry
Engine Testing: Measure the torque of the crankshaft and gearbox. Optimize power output and fuel efficiency.
Electric Power Steering (EPS) System: Real-time detection of steering wheel torque. Provide fine power assistance. Improve driving comfort.
New Energy Vehicle Motor Testing: Ensure motor efficiency and control system stability. Extend battery life.
Tire Testing: Monitor the friction between tires and the ground. Optimize vehicle handling performance.
Industrial Automation and Robotics
Robot Arm Torque Control: Ensure the fine force when the robot grabs objects. Avoid damage to workpieces or injuries.
Automated Assembly Line: Monitor screw tightening torque. Ensure product assembly quality (such as mobile phones, auto parts).
CNC Machine Tools: Real-time monitoring of cutting torque. Prevent tool overload damage.
Energy and Wind Power Industry
Wind Turbine Monitoring: Real-time detection of spindle torque. Prevent overload failure. Extend equipment life.
Oil Drilling Equipment: Monitor drill pipe torque. Optimize drilling efficiency. Reduce equipment loss.
Hydropower Generator Set: Measure turbine torque. Ensure power generation efficiency.
Aerospace
Aircraft engine testing: Ensure that the torque output of turbine engines meets safety standards.
Spacecraft attitude control: Torque monitoring for satellite solar panels. Ensure stable deployment.
UAV propeller testing: Optimize power system efficiency. Improve endurance.
Medical and Precision Instruments
Surgical robots: Provide fine force feedback to improve surgical safety.
Rehabilitation equipment: Monitor the patient’s joint activity torque. Customize rehabilitation plans.
Micro motor testing: Torque calibration of drone motors and precision instruments.
Consumer Electronics and Home Appliances
Power tools: Torque control of electric drills and screwdrivers. Prevent overtightening.
Home appliances: Torque monitoring of washing machine drums. Optimize washing results and reduce noise.
Torque Sensor Installation and Precautions
There are some key points to note when installing the torque sensor.
When installing, make sure it is placed horizontally. Ensure its accuracy and stability.
Although vertical installation is different from horizontal installation. It is also critical to the accuracy and stability of the sensor. When implementing vertical installation, the installation guide should be carefully followed. Ensure the sensor can be correctly and firmly fixed in the predetermined position. To effectively ensure the accuracy and stability of its torque measurement.
Precaution:
1. Make sure that the power equipment, sensor and load equipment are firmly placed on the foundation. Prevent data instability, reduced measurement accuracy or sensor damage due to vibration. It is recommended to use an elastic pin coupling or a rigid coupling for connection.
2. Carefully adjust the center height and coaxiality of each device. Ensure that its deviation is less than 0.05mm and fix it.
3. The installation environment of the torque sensor should also be paid attention to. The temperature should be between 0℃ and 60℃, the relative humidity should be less than 90%,
4. An environment without flammable and explosive materials should be selected. Strong electromagnetic interference should be avoided.
Torque Sensor Troubleshooting
Common faults and treatments
1. Unstable signal:
- Check whether the wiring is loose and whether the sensor is disturbed by external forces.
- Adjust the filter parameters or change the signal transmission method.
2. Large measurement error:
- Recalibrate the zero point and range.
- Confirm the accuracy of the standard weight and check the impact of environmental vibration.
3. Display abnormality (such as garbled characters):
- Restart the device or check the motherboard/signal line fault.
- Refer to the manual to check the error code.
Can a Force Sensor Measure Force?
Yes
A force sensor is a device that converts the value of force into a related electrical signal. Force is the direct cause of the change in the movement of matter. Specific devices include metal strain gauges, pressure sensors, etc.
In power equipment, engineering machinery, various machine tools and industrial automation systems. The torque sensor has become an indispensable core component.
Force sensors are mainly composed of three parts:
1—Force sensitive element (i.e., elastic body. Common materials include aluminum alloy, alloy steel and stainless steel）
2—Conversion element (the most common is a resistance strain gauge).
3—Circuit part (usually enameled wire, PCB board, etc.).
What do Force Sensors Detect?
Force sensors can detect mechanical quantities. such as tension, pull, pressure, weight, torque, internal stress and strain.
What Sensors Measure Torque?
Torque Wrench
A torque wrench is one of the most common torque measurement tools. It is widely used in mechanical assembly and maintenance. It ensures that the bolt or nut reaches the required torque when tightening by presetting the torque value. Common torque wrenches include mechanical torque wrenches, electronic torque wrenches and hydraulic torque wrenches.
Torque Sensor
A torque sensor is a high-precision measurement tool. It is usually used for real-time torque monitoring in laboratories or production lines. It can convert torque signals into electrical signals for data recording and analysis.
Torque Tester
A torque tester is a multifunctional measuring device. It is suitable for torque measurement of various rotating parts. It is usually equipped with a display screen that can display torque values in real time and supports data storage and export. Torque testers are widely used in motor testing, engine testing and other fields.
Torque Multiplier
A torque multiplier is an auxiliary tool. It amplifies the operator’s input torque through the principle of gears or levers. It is suitable for occasions where high torque is required. But the operating space is limited. It is usually used in conjunction with a torque wrench. Ensure high-precision measurement.
Torque Screwdriver
A torque screwdriver is a small torque measurement tool. It is suitable for precision assembly and maintenance of small equipment. It can accurately control the tightening torque of the screw to avoid damage to parts due to over-tightening.
Sino Inst is a torque supplier from China. We have much experience in torque measurement. If you have any questions related to torque measurement. Our professional engineers will solve them for you.
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