Torque (torque) is the magnitude of moment in physics, which is equal to the product of force and moment arm, and the international unit is Nm. In terms of motors, the moment arm is the radius of rotation of the object driven by the motor. If the torque of the motor is too small, the object to be carried cannot be moved, that is, it feels that the "strength" of the motor is not strong enough. In layman's terms, the "strength" of the motor driving the mechanical rotation is the torque of the motor. In addition, we can also see the torque unit of kgm. Since G=mg, when g=9.8, 1kg=9.8N, so 1kgm=9.8Nm, and the pound-foot lb-ft is the imperial torque unit, 1lb=0.4536kg ; 1ft=0.3048m, can calculate 1lb-ft=0.13826kgm. In people's daily expressions, torque is often referred to as torque (these are two different concepts in physics).
Now give an example: the torque of the 8th generation Civic 1.8 is 173.5Nm at 4300rpm, which means that the output torque of the engine is 173.5Nm at 4300 rpm. How can the power of 173.5N make a car with more than 1 ton run? In fact, the torque from the engine has to be amplified (at the cost of reducing the speed at the same time), which depends on the gearbox, final transmission and tires. The torque released by the engine is first passed through the gearbox for "adjustable" torque amplification (or reduction in over-ratio gear), and then transmitted to the final transmission (tail teeth) for further amplification (while the speed is further reduced), and finally through the tires Unleash the drive. For example, if the 1st gear ratio of a car (the gear ratio, the essence is the gear radius ratio) is 3, the tail tooth is 4, the tire radius is 0.3 meters, and the original torque is 200Nm, the final torque on the axle becomes 200 ×3×4=2400Nm (assuming the transmission efficiency is 100%), after dividing by the tire radius of 0.3 meters, the friction part between the tire and the ground will have a driving force of 2400Nm/0.3m=8000N, which is enough to drive the car.
When it comes to mechanical efficiency, every time a gear is transmitted, there will be a power loss. The mechanical efficiency of the manual transmission is about 95%, and the automatic transmission is worse, with about 88%. The efficiency is about 98%. On the whole, the driving force of a car can be calculated by the following formula: torque x gearbox gear ratio x final gear ratio x mechanical efficiency
Note: It should be noted that if the torque is calculated through the reducer, the factor of gear transmission efficiency loss should be considered.
