Engine Brake Torque Ramp Control for Jerk Reduction
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Solution Overview
Problem
Engine braking in vehicles often results in sudden jerks due to instant disengagement of the engine brake, which compromises drivability and driver comfort, as the transition from negative to zero or positive torque is abrupt, leading to significant vehicle acceleration variations.
Innovation Solution
A controller-based system that gradually disengages the engine brake using a predefined torque ramp rate, allowing for a smoother transition from negative to zero or positive torque, thereby reducing vehicle acceleration variations and minimizing cab jerk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine brake is disengaged instantly, then the response time is fast, but the vehicle jerk increases significantly
Solution Approach 1:
The controller initiates a gradual disengagement process before the engine brake is fully disengaged. The negative torque is reduced incrementally over a predetermined time period according to a ramp rate, preparing the system for smooth transition and avoiding sudden torque changes that cause jerk.
Solution Approach 2:
The disengagement process is made dynamic by implementing a time-based ramp rate that gradually reduces the negative torque. The torque reduction follows an incremental pattern over a predetermined time period, allowing the system to adapt smoothly from the engaged to disengaged state without abrupt changes.
2Object-affected harmful factors
If the engine brake is disengaged gradually, then the vehicle jerk is reduced, but the disengagement time increases
Solution Approach 1:
The controller changes the torque parameter dynamically during disengagement by applying a predetermined ramp rate. The negative torque is reduced in controlled increments over a predetermined time period, optimizing the balance between smooth transition and acceptable disengagement duration.
Solution Approach 2:
The disengagement process maintains continuous control of the negative torque throughout the transition period. Rather than abrupt on/off switching, the torque is gradually reduced in a continuous manner over the predetermined time period, ensuring smooth acceleration transition and minimizing jerk while maintaining reasonable response time.
Data Source
AI summary
Systems and methods for controlling engine brake disengagement in a vehicle include a controller receiving a signal indicative of a command to disengage an engine brake while the vehicle engine is in engine brake engaged condition. The engine can be subjected to a first negative torque under the engine brake engaged condition. The controller can cause the engine brake to be gradually disengaged over a time period using a predefined torque ramp rate, responsive to the signal. The gradual disengagement of the engine brake can be in the form of a phased out disengagement, and can reduce vehicle engine jerk associated with engine brake disengagement.