Powertrain Torque Control for Smooth Simulated Gear Shifts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid vehicles with continuously variable transmissions experience abrupt changes in propulsive effort request and vehicle speed due to switching between torque maps, which can deviate from the operator's expected range, especially when simulating gear shifts in a powertrain without stepped gear ratios.
Innovation Solution
A method is developed to simulate gear shifting in a powertrain with a continuously variable transmission by gradually changing the propulsive effort request from one value to another through incremental adjustments while the propulsive effort pedal position remains constant, using a controller to manage powertrain torque and ensure smooth vehicle speed changes within an expected range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If torque maps are switched in a continuously variable transmission to simulate gear shifts, then transmission ratio changes are achieved, but abrupt changes in propulsive effort request and vehicle speed occur
Solution Approach 1:
The patent applies dynamics by making the propulsive effort request change dynamically over time rather than instantaneously. The controller adjusts the propulsive effort request at a controlled rate during simulated gear shifts, allowing the system to transition smoothly between different transmission ratio states while maintaining vehicle speed stability within an expected range.
Solution Approach 2:
The patent changes the parameter of propulsive effort request from a static value to a time-varying value during simulated gear shifts. By modifying how the propulsive effort request parameter evolves over time (using rate of change limitations), the system achieves smooth transitions that maintain vehicle speed stability while still accomplishing transmission ratio adjustments.
2Adaptability or versatility
If propulsive effort request is adjusted abruptly during simulated gear shifts, then transmission ratio changes are achieved, but vehicle speed changes deviate from operator's expected range
Solution Approach 1:
The patent makes the propulsive effort request adjustment dynamic by implementing a rate of change limitation. Instead of applying abrupt changes, the controller adjusts the propulsive effort request gradually over time, ensuring that vehicle speed changes remain within the operator's expected range and maintaining driving comfort during simulated gear shifts.
Solution Approach 2:
The patent uses feedback by monitoring the rate of change of the propulsive effort request and comparing it against expected ranges. The controller adjusts the propulsive effort request based on this feedback to ensure smooth transitions that match operator expectations, thereby improving driving comfort during gear shift simulation.
Data Source
AI summary
Methods and systems are provided for improving torque control of a vehicle that includes simulated shifting of a step gear ratio transmission. In one example, a propulsive effort request is gradually incrementally increased or decreased to provide a smooth torque transition, thereby providing a smoother vehicle speed change and improve vehicle drivability.