A transfer for a four-wheel drive vehicle, the four-wheel drive vehicle including a driving source, right and left main drive wheels, a power transmission member, and right and left auxiliary drive wheels, the transfer being configured to output part of driving force, which is transmitted from the driving source to the main drive wheels, to the auxiliary drive wheels via the power transmission member when a drive mode of the four-wheel drive vehicle has been changed from a two-wheel drive mode to a four-wheel drive mode, the transfer comprising:
- a ring gear having a cylindrical shape, the ring gear being supported so as to rotate around a rotation axis, and configured to drive the power transmission member;
- an input shaft extending through an inside of the ring gear, the input shaft being supported so as to rotate concentrically with the ring gear and, configured to receive part of the driving force that is transmitted from the driving source to the main drive wheels;
- a disconnect mechanism configured to connect the ring gear to the input shaft and disconnect the ring gear from the input shaft, wherein
- the disconnect mechanism is an intermesh disconnect mechanism and includes first teeth and a movable meshing member, wherein the first teeth are provided on the ring gear, wherein the movable meshing member includes second teeth configured to be engaged with or released from the first teeth, and wherein the movable meshing member is provided on the input shaft so as not to relatively rotate and so as to move in a direction of the rotation axis;
- and
- an actuator configured to change the disconnect mechanism between a connection position and a disconnection position, the connection position being a position at which the ring gear and the input shaft are coupled to each other so as not to relatively rotate, the disconnection position being a position at which relative rotation between the ring gear and the input shaft is allowed, wherein
- the actuator is configured to move the movable meshing member between the connection position and the disconnection position by using an electromagnet
- the actuator includes a trip mechanism, the electromagnet and a spring, wherein the trip mechanism and the electromagnet are configured to change the disconnect mechanism between the connection position and the disconnection position, wherein the spring is configured to urge the movable meshing member from the disconnection position toward the connection position, wherein
- the trip mechanism includes a first piston, a second piston and a holder, wherein
- the first piston is configured to be reciprocated by the electromagnet in the direction of the rotation axis by a predetermined stroke,
- the second piston is provided so as to relatively rotate with respect to the input shaft and is moved by the first piston against an urging force of the spring, and
- the holder has multi-step latch teeth and is provided on the input shaft so as not to relatively rotate or move in the direction of the rotation axis, the holder is configured to latch the second piston, moved by the first piston, with any one of the multi-step latch teeth,
- wherein the trip mechanism is configured to cause the second piston to move the movable meshing member to the disconnection position against the urging force of the spring by a predetermined number of times of reciprocating stroke of the first piston, and
- the trip mechanism is configured to, when the number of times of reciprocating stroke exceeds the predetermined number of times, unlatch the second piston and allow the movable meshing member to move to the connection position under the urging force of the spring.