Electrically actuated disc stack having low response time due to reduced residual magnetism for use in drives, brakes and combinations thereof

摘要

The present invention is an electrically actuated disc stack for drives, brakes and combinations thereof having minimized residual magnetism. Residual magnetism is minimized by the following features being provided, singly or in combination, in a drive, brake or combination thereof. 1) A non-magnetic material is located between the clutch armature plate and the clutch electromagnetic coil assembly, and a non-magnetic material is located between the brake armature plate and the brake electromagnetic coil assembly. The non-magnetic material serves as a spacer to add reluctance to the magnetic circuit and may be for example a wafer for instance composed of aluminum or stainless steel or may be a coating. 2) A driver circuit for energizing the primary and secondary electromagnetic coils, wherein the self-induced EMF produced when current is shut-off is rapidly dissipated. 3) Non-magnetic drive components are used in the path of the magnetic circuit of the clutch and brake electromagnetic coil assemblies. For example, the portion of the drive shaft concentric with respect to the clutch electromagnetic coil assembly is composed of a non-magnetic metal, such as aluminum. This has the effect to reduce residual magnetism in that the drive shaft will not be contributing its own permanent magnetism acquitted during energization of the primary electromagnetic coil.