Electric motor

US6191516A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Peter Froehlich · Schwanau, DE
• Joerg Brandes · Baden-Baden, DE
• Hans Kobschaetzky · Renchen, DE

Key dates

• Filing date: Dec 14, 1999
• Grant date: Feb 20, 2001
• Expiry date: Dec 14, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02K23/04
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

An electric motor, including at least two permanent magnet segments disposed around a motor longitudinal axis, in which each permanent magnet segment has end faces extending in the direction of the motor longitudinal axis and is encompassed by two independent yoke ring segments that have a gap between them parallel to a symmetry plane extending through the motor longitudinal axis and the center of the permanent magnet segments in order to reduce the armature transverse field. In addition to the reduction of the armature transverse field, a weight reduction of the electric motor is also achieved. To this end, in a first region close to the end faces of the permanent magnet segments, the one-piece magnetically conductive yoke is provided with a larger cross section than in a second region close to the symmetry plane extending through the center of the permanent magnet segments. The construction is particularly suited for small electric motors, in particular d.c. motors that are excited by permanent magnets.