Power transmission control device

A power transmission control device comprising:

• a first rotation shaft;
• a power source which is connected to the first rotation shaft so that a first rotation speed corresponding to a rotation speed of the first rotation shaft is adjustable;
• a second rotation shaft which rotates together with an axle and is different from the first rotation shaft;
• a first rotation speed detection unit which detects the first rotation speed;
• a second rotation speed detection unit which detects a second rotation speed corresponding to a rotation speed of the second rotation shaft;
• a power transmission unit which includes a plurality of power transmission paths between the first rotation shaft and the second rotation shaft;
• and
• a control unit,
• wherein the power transmission unit includes at least:
• a first deceleration mechanism which transmits power between the first rotation shaft and the second rotation shaft;
• a second deceleration mechanism which transmits power between the first rotation shaft and the second rotation shaft and has a deceleration ratio different from that of the first deceleration mechanism;
• and
• a switching mechanism which changes a power transmission state between the first deceleration mechanism and the second deceleration mechanism,
• wherein the control unit is configured to perform each of at least
• a switched rotation speed calculation process of calculating a switched rotation speed corresponding to the first rotation speed after the power transmission state is switched to be established by the second deceleration mechanism on the basis of the second rotation speed detected by the second rotation speed detection unit when the power transmission state established by the first deceleration mechanism is switched to the power transmission state established by the second deceleration mechanism,
• a synchronization control process of controlling the rotation speed of the first rotation shaft by the power source so that the first rotation speed is synchronized with the switched rotation speed calculated by the switched rotation speed calculation process after the power transmission state by the first deceleration mechanism is released, and
• a switching control process of controlling the switching mechanism so that the power transmission state by the second deceleration mechanism is established after the first rotation speed is completely synchronized with the switched rotation speed calculated by the switched rotation speed calculation process in the synchronization control process,
• wherein in the switching control process, the control of the switching mechanism is started to establish the power transmission state by the second deceleration mechanism before the first rotation speed is completely synchronized with the switched rotation speed calculated by the switched rotation speed calculation process,
• wherein the switching mechanism includes:
• an engagement member that is provided to be rotatable along with any one of the first rotation shaft and the second rotation shaft and to be movable in the axial direction of the one shaft and is disposed between the first deceleration mechanism and the second deceleration mechanism;
• and
• an actuator which is operated to move the engagement member in the axial direction,
• wherein the first deceleration mechanism is configured to establish the power transmission state by engaging with the engagement member when the engagement member moves toward the first deceleration mechanism in the axial direction,
• wherein the second deceleration mechanism is configured to establish the power transmission state by engaging with the engagement member when the engagement member moves toward the second deceleration mechanism in the axial direction,
• wherein the actuator includes an operation amount detection unit which detects an operation amount of the actuator,
• wherein the control unit is configured to perform each of
• a differential rotation calculation process of calculating a differential rotation change rate corresponding to a change amount per unit time of a differential rotation and the differential rotation corresponding to a rotation speed difference between the switched rotation speed and the first rotation speed, and
• a required operation amount calculation process of calculating a required operation amount corresponding to an operation amount of the actuator necessary until the engagement member starts to engage with the second deceleration mechanism, and
• wherein in the switching control process, an operation speed of the actuator is determined on the basis of the differential rotation and the differential rotation change rate calculated by the differential rotation calculation process and the required operation amount calculated by the required operation amount calculation process.