On Selecting the Air-Gap Value of a Magnetoelectric Valve Motor

The influence of the air gap of a valve motor with permanent magnets on the sources of its vibration and noise of electromagnetic nature is considered. It is shown that, when the air gap is doubled, the average value of the magnetic induction in the gap decreases by about 4%, and so the radial electromagnetic forces proportional to the square of the average value of the induction will also decrease slightly. The average values of electromagnetic power and electromagnetic torque are reduced by 2.2%. However, an increase in the air gap causes a rather strong decrease in the higher harmonics of magnetic induction in the gap, which are the source of the oscillation of the electromagnetic torque of the engine. Calculations show that the amplitude of the variable component of the torque is reduced by 15% in an engine with a double clearance.