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US 7,559,752 B2Granted
Dual-shaft vacuum pump
AssigneeOerlikon Leybold Vacuum GmbH
InventorsRudolf Bahnen, Josef Hodapp, Karl-Heinz Ronthaler
Life of this patent
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Abstract
A two-shaft vacuum pump has a simplified drive motor. The two-shaft vacuum pump has a synchronous motor as a drive motor which motor rotor is permanently excited. Permanently excited motor rotors are sufficiently small and of light weight such that rotor supporting bearings can be omitted. This also eliminates the problems associated with cooling and lubrication of the supporting bearings.
Claims14
A two-shaft vacuum pump comprising:
- first and second rotor shafts,
- an electric drive motor which drives one of the rotor shafts, the drive motor being a synchronous motor with a motor rotor that is permanently excited, and
- a synchronous motor power-limiting device which limits compression-induced heating in the motor rotor to a constant value at speeds above a fixed rated motor speed (nN) by limiting motor power (PM) to a fixed maximum motor power (PMmax) in a limiting range above a fixed rated motor speed (nN);
- wherein above the fixed rated motor speed, a stator current is adjusted such that motor torque (MM) decreases reciprocally proportional to the motor speed as the motor speed increases.
1 more element
A two-shaft vacuum pump comprising:
- a pair of rotor shafts;
- a synchronous, permanently excited drive motor directly connected to one of the rotor shafts;
- and
- a phase angle adjusting device which (a) below a rated motor speed, adjusts a phase angle between a motor rotor magnetic field and at least one of a motor stator magnetic field and a stator current and (b) at the rated motor speed (nN), limits compression induced heating to a constant value by adjusting a stator current to fix an applied motor power (PMmax) such that motor torque (MM) decreases reciprocally proportional to motor speed with increasing motor speed.
1 more element
Dependencies are inferred from the claim text.