Dog clutch engagement control system

A dog clutch engagement control system, comprising:

• a dog clutch that includes:
• a first clutch member which is coupled to an input shaft and has a plurality of first engagement teeth arranged in a circumferential direction of the dog clutch;
• and
• a second clutch member which is coupled to an output shaft and has a plurality of second engagement teeth arranged in the circumferential direction, wherein the plurality of second engagement teeth are configured to engage with the plurality of first engagement teeth directly or indirectly via a relay member, and the dog clutch is configured to switch between an engaged state, in which the first clutch member and the second clutch member are engaged with each other, and a disengaged state, in which the first clutch member and the second clutch member are disengaged from each other;
• a clutch actuator that is configured to relatively move the first clutch member and the second clutch member relative to each other in an axial direction of the dog clutch, or, relatively move the relay member in the axial direction relative to the first clutch member and the second clutch member in a case where the relay member is used;
• a phase difference sensor that is configured to detect a phase difference between the first clutch member and the second clutch member;
• and
• a controller that is configured to:
• control an input-output rotational speed difference, which is a difference between a rotational speed of the input shaft and a rotational speed of the output shaft;
• in response to an engagement instruction, which instructs to shift the dog clutch from the disengaged state into the engaged state, execute a synchronization operation to gradually decrease the input-output rotational speed difference until the input-output rotational speed difference reaches a target rotational speed difference at which the dog clutch is shiftable into the engaged state;
• in the synchronization operation, with respect to an engagement timing, at which the phase difference reaches an allowable phase difference that allows the dog clutch to be shifted into the engaged state, detect a current latest engagement timing, which is the engagement timing detected most recently, based on an output of the phase difference sensor;
• and
• output a drive instruction to the clutch actuator to cause the dog clutch to be shifted into the engaged state at one of a plurality of future engagement timings, each of which is subsequent to a timing at which the input-output rotational speed difference reaches the target rotational speed difference, wherein:
• after reaching an adjustment reference time point, at which the input-output rotational speed difference reaches a phase-difference-detectable rotational speed difference that allows the phase difference sensor to detect the phase difference, the controller is configured to adjust the phase difference between the first clutch member and the second clutch member based on information, which is obtained at an arbitrary phase difference detection time point where an arbitrary phase difference is detected according to the output of the phase difference sensor, by changing a change characteristic of the input-output rotational speed difference, such that the one of the plurality of future engagement timings coincides with a target completion time point that is a time point at which a target completion time length elapses from the adjustment reference time point.