Vehicle Control Device Slip Engagement Shock Reduction
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Solution Overview
Problem
Existing vehicle drive system control devices experience shock during internal combustion engine start due to timing mismatches between torque direction reversal and engine start, particularly when the torque changes from positive to negative, leading to inefficient torque transfer and increased shock.
Innovation Solution
An electronic control unit is implemented to manage the second engagement device in a slip engagement state, maintaining the rotating electric machine's speed higher than the synchronous speed when the accelerator operation decreases, preventing torque direction reversal and reducing shock by limiting negative torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the threshold value for internal combustion engine start is set greater than the optimized value, then shock caused by torque direction reversal is reduced, but the timing of engine start is delayed
Solution Approach 1:
The control device performs preliminary action by controlling the second engagement device to be in a slip engagement state before the internal combustion engine starts. This preliminary slip control prepares the torque transfer path to smoothly accommodate the upcoming engine start and torque direction reversal, eliminating the need to delay engine start timing while still preventing shock.
Solution Approach 2:
The control device dynamically adjusts the engagement state of the second engagement device during the engine start process. By transitioning from direct engagement to slip engagement and back to direct engagement based on real-time conditions (engine start timing, torque direction, rotational speeds), the system optimizes both shock reduction and engine start timing without compromise.
2Ease of operation
If the required torque changes from positive to negative when accelerator operation decreases, then the rotational speed of the rotating electric machine transitions below synchronous speed, but shock occurs due to torque direction reversal in the second engagement device
Solution Approach 1:
The control device applies preliminary anti-action by detecting when the required torque is approaching zero and preemptively controlling the rotational speed of the rotating electric machine to remain above synchronous speed. This prevents the torque direction reversal that would cause shock in the second engagement device, while still allowing natural response to accelerator operation changes.
Solution Approach 2:
The control device uses the rotational speed of the rotating electric machine as an intermediary parameter to mediate between the driver's accelerator input and the torque transfer through the second engagement device. By maintaining the rotational speed above synchronous speed, the system acts as a buffer that prevents direct torque direction reversal shock while preserving operational responsiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for smooth torque transfer and quick engine start without staggering the torque direction reversal timing, reducing shock and maintaining efficient engine operation even when the torque changes from positive to negative.
Implementation Method 1
a second engagement device CL2 arranged sequentially from the internal combustion engine side in the power transfer path; bring the second engagement device into a slip engagement state
Implementation Method 2
a rotating electric machine MG arranged sequentially from the internal combustion engine side in the power transfer path; perform slip control that controls the rotating electric machine
Data Source
AI summary
A control device for controlling a vehicle drive system in which a first engagement device, a rotating electric machine, and a second engagement device are provided in a power transfer path connecting an internal combustion engine to wheels and are arranged sequentially from an internal combustion engine side, the control device including an electronic control unit.