Clutch control device for 4-wheel drive vehicle

A clutch control device for a four-wheel drive vehicle having a pair of main drive wheels and a pair of auxiliary drive wheels which are selectively connected to the drive source, the clutch control device comprising:

• a dog clutch operatively disposed in a transmission path between the main drive wheels and the auxiliary drive wheels to separate a system for transmitting drive force to the auxiliary drive wheels from a system for transmitting drive force to the main drive wheels by releasing the dog clutch;
• a friction clutch operatively disposed in a transmission path between the main drive wheels and the auxiliary drive wheels to allocate a portion of the drive force from the drive source to the auxiliary drive wheels in accordance with a clutch engagement capacity of the friction clutch;
• and
• a clutch controller operatively coupled to the dog clutch and the friction clutch to selectively carry out a control of starting an engagement of the dog clutch, which is in a disengaged state, after putting the dog clutch into a rotationally synchronized state by engaging the friction clutch, in response to a request to engage the dog clutch,
• the clutch controller being programmed to selectively establish a disconnected, two-wheel drive mode in which the dog clutch and the friction clutch are disengaged, a standby two-wheel drive mode in which the dog clutch is engaged and the friction clutch is disengaged, and a connected, four-wheel drive mode in which the dog clutch and the friction clutch are engaged, and
• the clutch controller being programmed to set an engagement start timing of the friction clutch when a transition is made to the connected, four-wheel drive mode to an earlier timing as compared to when a transition is made to the standby two-wheel drive mode, in response to a request to engage the dog clutch while in a state in which the disconnected, two-wheel drive mode is selected.