Powertrain Control Method for Extraordinary Gear Shifts
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Solution Overview
Problem
Existing vehicle drivetrain systems face limitations in gear shifts due to engine torque restrictions, which can lead to inefficient fuel consumption and engine wear, particularly when high engine speeds are maintained unnecessarily.
Innovation Solution
A control method for the powertrain that allows extraordinary gear shifts by temporarily increasing the engine output torque limit based on parameters like fuel efficiency, future torque demand, and engine temperature, enabling gear shifts that would otherwise be restricted, while ensuring the engine operates within safe and efficient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gear shifts are restricted by general torque limits to protect the engine and reduce wear, then engine reliability is improved, but fuel consumption increases due to unnecessary high engine speeds
Solution Approach 1:
The torque limit is made dynamic rather than static. The system switches between a first general torque limit under normal conditions and a second temporarily increased torque limit when extraordinary gear shifts are needed. This dynamic adjustment allows the system to adapt to changing driving conditions, permitting high-speed gear shifts when beneficial for fuel economy while maintaining protective limits during normal operation.
Solution Approach 2:
The system changes the torque limit parameter based on driving conditions. When an extraordinary gear shift is detected (high engine speed with no immediate torque demand), the torque limit parameter is temporarily increased from the first general limit to a second higher limit, enabling the gear shift to occur. This parameter change resolves the contradiction by allowing the system to exceed normal limits when beneficial while maintaining them during normal operation.
2Use of energy by moving object
If gear shifts are allowed based on predefined strategies to reduce fuel consumption, then fuel efficiency is improved, but engine wear increases due to excessive engine speeds
Solution Approach 1:
The torque limit adjustment creates a dynamic protection mechanism. During extraordinary gear shifts, the temporarily increased limit allows the shift to occur despite high engine speed, but the limit returns to the first general level afterward, providing ongoing protection against excessive wear. This dynamic approach balances fuel efficiency improvements with long-term engine health.
Solution Approach 2:
The system performs preliminary assessment of driving conditions before allowing extraordinary gear shifts. By detecting when high engine speed is occurring without immediate torque demand, the system proactively permits the gear shift before excessive wear can occur, then immediately restores protective limits. This preliminary action prevents wear while enabling fuel-efficient operation.
3Productivity
If the engine torque limit is temporarily increased to allow extraordinary gear shifts, then drivetrain performance is improved, but the risk of engine damage increases
Solution Approach 1:
The torque limit is dynamically adjusted only temporarily during extraordinary gear shifts rather than being permanently increased. The system switches from the first general limit to a second higher limit only when needed, then returns to the original limit. This temporary dynamic adjustment enables improved drivetrain performance during the shift while maintaining long-term engine safety through the restoration of protective limits.
Solution Approach 2:
The increased torque limit is applied periodically and temporarily only during the specific window when an extraordinary gear shift is detected and executed. The system monitors engine conditions continuously and applies the higher limit only during the brief period when beneficial, then reinstates the lower protective limit. This periodic application minimizes exposure to high-stress conditions while achieving performance benefits.
Data Source
AI summary
A control method is provided for a powertrain in a vehicle, the powertrain including an engine mechanically connected to a gearbox and an Electronic Control Unit (ECU), wherein the method includes allowing an extraordinary gear shift in spite of a first torque comparison indicating an expected engine output torque demand above a first general limit for allowed output torque associated with the extraordinary gear shift provided that: a second torque comparison indicates that the expected engine output torque demand after the extraordinary gear shift is within the limits of a second temporarily increased allowed engine output torque limit; and an extraordinary gear shift criteria is fulfilled indicating a gear shift is allowed the criteria being dependent on at least one parameter chosen among estimated fuel efficiency, engine efficiency, expected future torque demand, time of running the engine above the general engine torque limit and engine temperature.