Gear Shift Control for Heavy-Duty Vehicle Uphill Torque Management
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Solution Overview
Problem
Manual gear shifting in heavy-duty vehicles, especially when traveling uphill, is challenging due to torque interruptions and speed reductions, requiring precise timing from the driver to avoid engine stalls or fuel cuts, which can lead to discomfort and reduced vehicle performance.
Innovation Solution
A method and system that uses an electronic control unit to monitor vehicle operating conditions, determine a desired shift point and target engine speed based on parameters like current engine speed, gradient, and torque, allowing for optimal timing of gear shifts to prevent engine speed from exceeding maximum limits, thereby reducing the risk of failed upshifts and improving driver comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If pre-engagement of expected subsequent gear is used to speed up shifting, then shifting time is reduced, but torque interruption and rotation speed errors cause jerks and shocks during shifting
Solution Approach 1:
The control system pre-engages the expected subsequent gear while the current gear is still engaged, preparing the transmission for the upcoming shift. This preliminary action reduces the actual shifting time and minimizes torque interruption, as the subsequent gear is already in position and ready for engagement.
Solution Approach 2:
The control system continuously monitors engine speed, vehicle speed, and transmission state to detect rotation speed errors during pre-engagement. Based on this feedback, the system adjusts the timing and manner of gear engagement to minimize jerks and shocks, ensuring smooth transitions.
2Object-affected harmful factors
If shifting is performed carefully to avoid jerks and shocks, then comfort is improved, but shifting time is extended leading to vehicle speed reduction
Solution Approach 1:
The system performs pre-engagement of the subsequent gear before the actual shift is initiated, so that when the shift is executed, the transmission is already prepared. This allows the shift to be completed quickly and smoothly, maintaining both comfort and speed.
Solution Approach 2:
The control system maintains continuous monitoring and adjustment during the shifting process, ensuring that torque transmission remains as continuous as possible. By managing the transition smoothly without complete torque interruption, the system maintains vehicle speed while ensuring comfort.
3Stability of the object's composition
If manual upshift request is made early to avoid maximum engine speed, then engine speed control is improved, but engine torque becomes too low causing vehicle to stall on uphill
Solution Approach 1:
The control system continuously monitors engine speed, vehicle speed, and road gradient to determine the optimal shift timing. Based on this feedback, the system delays the upshift until the engine speed and torque are sufficient to maintain vehicle operation on uphill, preventing stalls while still controlling maximum engine speed.
Solution Approach 2:
The control system dynamically adjusts the shift timing based on real-time operating conditions. When uphill gradient is detected, the system adapts the shift strategy to maintain adequate torque, making the shift control flexible and responsive to changing conditions rather than following a fixed schedule.
4Reliability
If manual upshift request is made late to ensure adequate engine torque, then vehicle performance on uphill is improved, but engine speed reaches maximum causing fuel cut and loss of propulsive torque
Solution Approach 1:
The control system continuously monitors engine speed and compares it against maximum allowed engine speed thresholds. Based on this feedback, the system initiates the upshift at the optimal moment that ensures adequate torque for uphill operation while preventing the engine speed from reaching the maximum that would trigger fuel cut.
Solution Approach 2:
The system prepares for the upshift in advance by monitoring engine speed trends and predicting when the optimal shift point will be reached. This preliminary preparation allows the system to execute the shift at the precise moment that balances torque requirements with engine speed limits, avoiding fuel cut conditions.
Data Source
AI summary
The invention relates to a method and an arrangement for controlling a gearshift in a vehicle with a transmission (120) comprising a stepped gearing, the transmission (120) being arranged between an engine (110) and at least one driven axle (123), wherein the engine and the transmission are controlled by an electronic control unit (140), The method involves monitoring at least one parameter related to a vehicle operating condition; registering that a manual upshift command is requested; determining a desired shift point and a target engine speed based on a parameter comprising at least current engine speed; and performing an upshift when the target engine speed is reached.