Hybrid Drive Engagement Control for Differential Gear Synchronization
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Solution Overview
Problem
The challenge of smoothly engaging the second engagement device when transitioning from an electric torque converter mode to a hybrid mode due to differences in rotation speeds between the internal combustion engine and the rotary electric machine, particularly in a differential state where each rotation element rotates at a constant speed.
Innovation Solution
A control device that manages the engagement process by executing asynchronization and synchronization maintaining controls to align rotation speeds, allowing the second engagement device to be smoothly engaged during mode transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second engagement device is engaged when transitioning from eTC mode to hybrid mode in a differential state where each rotation element rotates at a constant speed, then the mode transition can be completed, but the engagement cannot be performed smoothly due to rotation speed differences between the internal combustion engine and the rotary electric machine
Solution Approach 1:
The patent applies the dynamics principle by transitioning the distribution differential gear mechanism from a differential state to a non-differential state temporarily during mode transition. This dynamic state change allows the rotation elements to synchronize their speeds, enabling smooth engagement of the second engagement device. After engagement, the system returns to the differential state for normal operation. This resolves the contradiction by making the engagement process feasible (improving ease of operation) while maintaining reliability through proper speed synchronization.
2Reliability
If the rotation speed of the rotary electric machine is controlled to match the internal combustion engine speed during mode transition, then smooth engagement is achieved, but the control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the rotation speeds of the internal combustion engine and the rotary electric machine before engaging the second engagement device. The control device executes speed synchronization control in advance, ensuring that the rotation speed difference falls within a predetermined range before the engagement operation. This preliminary speed matching simplifies the overall control process by breaking it into distinct phases (synchronization phase followed by engagement phase), thereby reducing control complexity while maintaining engagement smoothness.
Data Source
AI summary
A distribution differential gear mechanism includes a first rotation element drivingly connected to input member, a second rotation element drivingly connected to output member, and a third rotation element drivingly connected to rotary electric machine. When rotation speed difference between rotation speed of the second and first rotation elements become equal to or less than synchronization threshold due to an increase in rotation speed of output member, control device executes synchronization maintaining control of maintaining rotation speed difference at specified difference rotation that is set to be equal to or less than synchronization threshold, by performing a rotation speed control of rotary electric machine in conjunction with rotation speed of second rotation element and by causing internal combustion engine to output a target torque, and control device executes engagement control of transitioning second engagement device from released state to engagement state while synchronization maintaining control is being executed.