TWO-STEP TRANSMISSION FOR ELECTRIC VEHICLE

The present invention relates to a two-speed transmission for an electric driving vehicle and the two-speed transmission for an electric vehicle has only one actuator. The transmission comprises a planetary gear mechanism (12), an elastic body (44), an armature (26) to integrally rotate with an input axis, an electromagnetic coil (46) and a multi-plate friction clutch (30) . Aring gear (20) is fixed to a housing. The armature (26) comprises clutch projection portions (26-1). A dog clutch is constituted by the clutch projection portions (26-1) and recess portions (18-2) of a sun gear (18). When the electromagnetic coil (46) is not electrically energized, the dog clutch is engaged. The rotation of the input axis is reduced and is transmitted to an output axis via the sun gear (18) and a carrier (16). When the electromagnetic coil (46) is electrically energized, the armature (26) is displaced against elastic force, the dog clutch becomes a non-engaging state, a multi-plate friction clutch (30) becomes an engaging state by pressing flange portions (26-4) of the armature (26) and the rotation of the input axis is transmitted to the output axis with a one-to-one relationship. The transmission can comprise a one-way clutch to prevent torque interruption when switching the gear ratio.