Patent ID: 6853160

Claim:
An air conditioning valve actuator for a motor vehicle comprising: a stepper motor means having a permanent magnet with a mechanical power output of at least 50 mW, said stepper motor means for producing an angular pitch and an outlet torque, said stepper motor means having a volume of copper therein and a length of the copper in coils, said stepper motor means having a working frequency and a starting frequency; a reducing means cooperative with said stepper motor means for reducing an amplitude of the angular pitch and for increasing the outlet torque, said stepper motor means defined by relationship of 10 −6 <γ 2 /R 0 <50 −6 where γ is the torque constant proportional to a volume of said permanent magnet, R 0 is a characteristic coefficient of the volume of copper and the length of the average turn of the coils, R 0 =ρLsp/(Scu.σ) in which ρ is a resistivity of copper and in which Lsp is a length of the average turn of a coil and in which Scu is a copper section of the coil and in which σ is a filling coefficient of the coil; a power supply connected to said stepper motor means, said power supply having a frequency and a current supply; and controlling means interactive with said power supply and said stepper motor means, said controlling means for gradually accelerating the frequency of said power supply to the coils of said stepper motor means to reach the working frequency of said stepper motor means, said working frequency being higher than said starting frequency.