Patent ID: 7214155

Claim:
An electric drive unit for a motor vehicle, comprising: (a) an electric motor having a motor housing fixed in non-rotatable manner; (b) a stator of said electric motor, with the stator being mounted in the motor housing and having coil-wound poles; (c) a rotor of the electric motor arranged internally of the stator, with an air gap being present between the pole faces of the stator and the outer periphery of the rotor facing said pole faces of the stator; (d) a planetary gear system having a sun wheel, a planet carrier, planet wheels and a ring gear, (e) the rotor of the electric motor and the sun wheel of the planetary gear system being coupled for torque transmission; (f) a gear casing of the planetary gear system, the gear casing being attached to the motor housing or at least in part being an integral component part of the motor housing; wherein: (g) the planet wheels of the planetary gear system are stepped planet wheels comprising a first toothed portion of larger diameter and a second toothed portion of smaller diameter, the first toothed portions of the stepped planet wheels engaging the sun wheel and the second toothed portions of the stepped planet wheels engaging the ring gear; (h) an imaginary common envelope cylinder for all outer diameters of the first toothed portions of the stepped planet wheels is located radially inside of winding heads present on one axial side of the stator as well as axially beside the portion of the rotor adjoining the air gap, and the first toothed portions of the stepped planet wheels project in axial direction outwardly beyond said winding heads either not at all or with less than 50% of their tooth width in engagement with the sun wheel; and (i) the second toothed portions of the stepped planet wheels have their outer diameters project into a space of the rotor which is axially recessed from the face side of the rotor present at the portion of the rotor adjoining the air gap.