Two-speed transmission for electric driving vehicle

A two-speed transmission for an electric driving vehicle disposed on an output axis of an electric motor in a vehicle which uses said electric motor for driving wheels, comprising:

• a housing fixed to a vehicle body side,
• a planetary gear mechanism which is disposed in said housing and comprises three rotational components including a carrier to rotatably support plural pinions disposed at a circumferential direction with an interval, a first gear whose rotational center is common to said carrier and which meshes with said pinions, and a second gear whose rotational center is common to said carrier, whose tooth number is different from a tooth number of said first gear, and which meshes with said pinions,
• an elastic body,
• an electromagnetic coil,
• an armature which is movable along an input axis, is rotated with said input axis, is moved to and is urged to a first direction by said elastic body, and is moved to and is urged to a second direction which is opposite to said first direction by an electromagnetic force generated from said electromagnetic coil,
• a first clutch which is engaged by movement of said armature to said first direction by an elastic force of said elastic body when said electromagnetic coil is not electrically energized, and is not engaged by movement of said armature to said second direction by said electromagnetic force against said elastic force when said electromagnetic coil is electrically energized, and
• a second clutch which is engaged by said movement of said armature to said second direction by said electromagnetic force against said elastic force when said electromagnetic coil is electrically energized, and is not engaged by said movement of said armature to said first direction by said elastic force when said electromagnetic coil is not electrically energized,
• wherein a ring gear or a sun gear as a first rotational component of said planetary gear mechanism is fixed to said housing, one of second and third rotational components is an input side rotational component and the other of said second and third rotational components is an output side rotational component, and said first and second clutches between said input side rotational component and said output side rotational component are determined such that a rotational velocity of said input side rotational component is equal to that of said output side rotational component when one of said first and second clutches is engaged and the other of said first and second clutches is not engaged, and said rotational velocity of said input side rotational component is not equal to that of said output side rotational component and a rotational direction of said input side rotational component is the same as that of said output side rotational component when one of said first and second clutches is not engaged and the other of said first and second clutches is engaged, and
• wherein, comparing a first case that said first clutch is engaged and said second clutch is not engaged by said movement of said armature to said first direction under said elastic force when said electromagnetic coil is not electrically energized with a second case that said first clutch is not engaged and said second clutch is engaged by said movement of said armature to said second direction under said electromagnetic force against said elastic force when said electromagnetic coil is electrically energized, a ratio of said rotational velocity of said output side rotational component to said rotational velocity of said input side rotational component in said first case is lower than that in said second case.