Two-Speed Transmission Control for Smooth Overdrive Shifts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing two-speed transmission systems with electric drive input face challenges in smooth overdrive upshifts, leading to unexpected acceleration and discomfort for drivers, particularly when shifting from first to second gear, due to the need for precise coordination between the electric machine and service brake.
Innovation Solution
A method that independently controls negative motor torque by the electric machine to maintain a constant vehicle speed during overdrive operation, avoiding sudden acceleration and allowing gearshifts to be triggered only by the driver's intention, thereby reducing the frequency of unexpected shifts and enhancing comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overdrive upshift is performed to prevent exceeding maximum rotational speed, then the electric machine's rotational speed is controlled, but the driver experiences unexpected acceleration and comfort is reduced
Solution Approach 1:
The control system performs preliminary action by detecting driver intent before the upshift is needed. When the driver requests positive torque (indicating desire for acceleration), the system prepares for upshift in advance, so that when the upshift occurs, it aligns with driver expectations rather than causing unexpected deceleration
Solution Approach 2:
The system uses feedback from the driver's torque requests to determine when to perform upshifts. By monitoring whether the driver requests positive or negative torque, the system adapts its upshift timing to match driver intentions, improving comfort while maintaining rotational speed control
2Ease of operation
If service brake is actuated during shifting to prevent unexpected acceleration, then driving comfort is improved, but control complexity increases due to precise coordination required
Solution Approach 1:
The invention extracts the brake actuation from the control process. Instead of coordinating the service brake with the electric machine during shifting, the system relies solely on the electric machine's torque control, eliminating the need for complex multi-component coordination while maintaining comfort
Solution Approach 2:
The electric machine performs self-service by independently managing the shifting process through torque control. The system uses the electric machine's ability to provide positive torque during upshifts to maintain speed, eliminating the need for external brake intervention and simplifying the overall control architecture
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents the electric machine from reaching its maximum rotational speed, ensures smooth transitions, and allows gearshifts to occur only when the driver desires, reducing the frequency of gearshifts and enhancing driving comfort by aligning shifts with the driver's wishes.
Implementation Method 1
the electric machine produces negative torque or overdrive torque, for example by virtue of recuperation
Data Source
AI summary
A method for the control of a two-speed transmission with an electric machine in a vehicle that is operating in overdrive. The motor torque (M) produced by the electric machine is at first controlled independently of a driver's indication (F) in such manner that an approximately constant vehicle speed is reached.