Torque is a force couple or moment that makes a mechanical element rotate (including a tendency to rotate), and is a special rotational moment. Mechanical components will have a certain degree of torsional deformation under the action of torque. Torque is a very important measurement item in the mechanical field and is closely related to many applications. Torque is the basic load form of various working machinery drive shafts, and is closely related to factors such as working capacity, energy consumption, efficiency, operating life and safety performance of power machinery. The torque measurement is of great significance to the determination and control of the transmission shaft load, the strength design of the working parts of the transmission system, and the selection of the prime mover capacity.
Torque is equal to the product of the force and the force arm or force couple arm. In the International System of Units (SI), torque is measured in Newton-meters (Nm). In addition, the relationship between torque and power is: T=9550P/n.
The rated torque of the motor indicates the output torque of the motor shaft end under rated conditions. The output torque at the shaft end of the motor is equal to the mechanical power output by the rotor divided by the mechanical angular velocity of the rotor. The greater the power the greater the torque. And the greater the number of magnetic poles of the motor with the same power, the greater the torque. The torque of the engine refers to the torque output by the engine from the crankshaft end. Under the condition of fixed power, it is inversely proportional to the engine speed. The faster the speed, the smaller the torque. Conversely the bigger the torque. It reflects the load capacity of the car within a certain range.
Torque measurement is almost everywhere, from screw tightening to wind power generation. The gas turbine produces a rated torque of 50 kNm and outputs up to 40 MW at 8000 rpm. The engine speed of F1 racing cars can be as high as 20,000 rpm, and the rated torque is as high as 2 kNm. Torque measurement has a wide range of applications, and it penetrates into various fields such as industry, agriculture, automotive, transportation, aerospace, defense, energy, and chemical industry.
Important Reasons for Torque Measurement:
1. Provide scientific data
Under the fierce competition of the market economy, many new mechanical products should not only develop in the direction of higher power, higher speed and higher efficiency, but also accelerate the development in the direction of smaller design margin. Torque measurement can provide scientific data for the design of rotating machinery.
2. Check whether the power machinery is qualified
Product quality is the life of an enterprise. Torque measurement is an essential means to check whether the power output of various types of power machinery meets the design targets. For example, motor laboratory, reducer laboratory, hydraulic laboratory, crane laboratory, and diesel engine laboratory all need to perform routine tests on torque, speed, power, and efficiency of their respective products. It is the torque sensor and the torque meter that are responsible for the detection of such parameters.
3. Real-time monitoring the running state of power machinery
Torque measurement is the main information source for various power machinery operating state monitoring and fault identification and prediction. For those large, critical, no reserved equipment, due to their unexpected shutdown or failure can cause great harm. Therefore it needs to be monitored. The main reasons are: 1) To ensure that the operating state is within the design constraints. 2) Indicate change or deterioration of alarm status to prevent equipment failure and costly secondary damage. 3) Provide an accurate description of the operating status of the equipment, from which the cycle and content of maintenance and overhaul can be determined.
4. Feedback signal for the automation control system
As a signal source in an adaptive control system. The torque sensor is connected to the adaptive control system as a signal sensitive element, and the torque signal is fed back to the system to realize automation control. For example, steel mills use torque meters to monitor the tightening torque value of steel pipe screws. When the tightening torque does not reach the specified value, the steel pipe continues to be tightened. When the tightening torque of the steel pipe reaches the specified value, the torque meter outputs the corresponding signal, and the tightening process is completed.
5. As an energy saving indicator
Use a torque measuring instrument to measure the efficiency of the new main engine put into operation, and then measure the efficiency again after running for a period of time. By comparing the two, the power consumption of the host can be judged and the repair period can be determined. For example, in order to determine the optimal working condition of the dredger, the torque measuring instrument is used to measure the output power of the main engine, and the flow meter is used to measure the amount of dredging. Compare the two to find the best working condition for the ratio of dredging amount to the output power of the main engine, saving energy.
6. As a dynamic balance indicator for a multi-host system
For example, aircraft and ships are basically multi-host systems. The power output of each host is basically the same, and the system is in normal operation. Equipped with a torque meter on each main engine, compared with each other to send out an unbalanced signal, and then adjusted system to power balance. In summary, the applications of modern torque measurement range from ships, drilling rigs, power generation equipment, metallurgy and mining machinery, to micro motors, household appliances, wave band switches, and watch hairsprings. The measurement of torque in various technical fields has attracted attention.