Vehicle Control Device Synchronizing Pseudo and Mechanical Gear Shifts
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Solution Overview
Problem
In vehicles equipped with both continuously variable and stepped variable transmissions, the irregular decrease in engine rotation speed during acceleration can cause discomfort to the driver, as the engine rotation speed is not uniformly increased with vehicle speed, leading to inconsistent pseudo and mechanical gear shifts.
Innovation Solution
A control device that adjusts the engine rotation speed by controlling the electronic control unit to increase the engine speed with vehicle speed, executing pseudo gear shifts and mechanical gear shifts at substantially the same rotation speed, thereby maintaining a consistent engine rotation speed increase rate and reducing driver discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the engine rotation speed is increased with vehicle speed during acceleration, then the driver's sense of discomfort is reduced, but the engine rotation speed becomes irregular when pseudo gear shift and mechanical gear shift occur at different speeds
Solution Approach 1:
The control device executes preliminary actions by adjusting engine rotation speed before mechanical gear shift occurs. When a mechanical gear shift is detected, the system proactively controls the engine speed to match the pseudo gear shift threshold value, ensuring synchronized operation before the actual shift happens. This preliminary coordination prevents irregular speed fluctuations and maintains driver comfort.
Solution Approach 2:
The control device implements feedback mechanisms by continuously monitoring engine rotation speed, vehicle speed, and transmission state. When detecting discrepancies between pseudo gear shift threshold and actual engine speed, the system adjusts engine output based on this feedback to maintain synchronization. This closed-loop control ensures consistent engine rotation speed during both pseudo and mechanical gear shifts.
2Productivity
If pseudo gear shift is executed to decrease engine rotation speed to match vehicle speed increase, then acceleration feeling is improved, but driver discomfort occurs when mechanical gear shift follows too quickly after pseudo gear shift
Solution Approach 1:
The control device acts as an intermediary between pseudo gear shift and mechanical gear shift operations. By introducing coordinated control logic that monitors both transmission types, the system mediates their interaction to prevent rapid succession. The control device ensures that mechanical gear shift is delayed or adjusted until engine speed synchronizes with pseudo gear shift threshold, preventing uncomfortable rapid shifts while maintaining acceleration performance.
3Ease of operation
If the engine rotation speed is controlled to increase uniformly with vehicle speed, then driver comfort is improved, but the gear shift synchronization between continuous and stepped transmissions becomes complex
Solution Approach 1:
The control device manages complexity by dynamically changing key parameters - specifically adjusting engine rotation speed targets based on transmission state. The system modifies the engine speed parameter to align with pseudo gear shift thresholds during mechanical gear shift events, creating synchronization without requiring complete redesign of the control architecture. This parameter-based approach simplifies the coordination of dual transmission systems.
Data Source
AI summary
A control device is configured to: (i) control rotation speed of internal combustion engine such that the rotation speed of the internal combustion engine is increased with an increase in a traveling speed of a vehicle, (ii) execute a pseudo gear shift to control the rotation speed of the internal combustion engine such that the rotation speed of the internal combustion engine is decreased to a first rotation speed, (iii) execute a mechanical gear shift to change a second gear ratio according to a gear shift line determined by the traveling speed and a value according to the acceleration request, and (iv) execute adjustment control to adjust the rotation speed of the internal combustion engine in advance in a period before executing the mechanical gear shift such that the rotation speed of the internal combustion engine matches the pseudo gear shift threshold value when the mechanical gear shift is performed.