Patent ID: 7906930
Filing Date: 2011-03-15
Classification: B60L,H02K,Y02T

Abstract:
1. A brushless electric machine, comprising: a first drive member having a plurality of permanent magnets; a second drive member having a plurality of electromagnetic coils, and capable of movement relative to the first drive member; a third drive member disposed to an opposite side from the first drive member with the second drive member therebetween, and having a fixed relative positional relationship with the first drive member; a magnetic sensor, disposed on the second drive member, for detecting relative position of the first and second drive members; and a control circuit for controlling operation of the brushless electric machine, based on an output signal of the magnetic sensor; wherein the third drive member has at locations facing the permanent magnets of the first drive member a plurality of magnetic field strengthening members for strengthening the magnetic field at the location of the second drive member in conjunction with the permanent magnets, and wherein the magnetic field strengthening members are ferromagnetic bodies excluding permanent magnets.