The cooling fan speed refers to the number of rotations of the fan blades per minute, in RPM. The speed measuring instrument is a measuring tool for measuring the speed of an object. Generally, a digital measuring instrument is used, as shown in the figure:
When the cooling fan is working, it mainly converts electrical energy into mechanical energy. The principle is mainly: when the cooling fan is powered, the fan coil has a current through it. According to the right-hand rule of Ampere, we know that a magnetic field is generated around the coil, and a rubber magnet with magnetic properties is attached to the inside of the fan blade. The magnetic field generated by the conductor generates a repulsive force with the fixed magnetic field. When the repulsive force is greater than the static friction of the fan (the friction of the fan bearing, the wind resistance of the blade rotation), the fan blade naturally rotates. The DC fan power supply voltage is fixed. The Hall sensing component must be used as a synchronous detection device to control a group of circuits so that the two sets of coils wound around the axis work in turn to generate different magnetic fields.
Through the working principle of the fan, we know that the main determining conditions of the fan speed are the structure and parts of the fan itself, the friction of the bearing and the wind resistance of the inclination of the blade. Of course, there are external factors. Let's analyze it below: the cooling fan is passed Air cooling to achieve heat dissipation, the main factor affecting air cooling is the environmental structure of the cooling system. When the system environment is relatively sealed, the wind pressure of the fan should be considered when selecting the cooling fan. The fan air pressure is not enough, the fan speed will be obvious. Affected, and the air volume is obviously reduced, the heat dissipation effect is not achieved, so the external wind pressure is a factor affecting the fan speed (the supercharged cooling fan can be overcome); another obvious factor is the external environment, such as sand, greasy In high-low temperature environment, if the ordinary cooling fan is not protected, the impact of the harsh environment on its speed is also obvious.a