Hybrid Powertrain Controller Gear Shift Logic
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Solution Overview
Problem
Existing vehicle transmission systems often shift gears unnecessarily, causing variations in output torque and engine sound, which can be uncomfortable for occupants, especially during steady-speed cruising or when transitioning between hybrid and electric modes.
Innovation Solution
A controller is programmed to maintain the current gear ratio when the traction battery state of charge is above a threshold and vehicle speed is constant, preventing unnecessary shifts during decoupling from the engine, and to transition between hybrid and electric modes without gear changes unless the accelerator pedal position exceeds a certain threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the transmission shifts gears in response to mode transitions or steady-speed conditions, then the engine speed can be optimized for efficiency, but occupants experience variations in output torque and engine sound that reduce comfort
Solution Approach 1:
The system dynamically adjusts transmission shifting behavior based on operating mode (hybrid vs. electric) and vehicle conditions. In hybrid mode, the transmission shifts to optimize engine efficiency, while in electric mode or during steady-speed cruising, the transmission maintains the current gear ratio to prevent unnecessary shifts and improve occupant comfort.
Solution Approach 2:
The controller changes the gear ratio parameter selectively based on mode transitions and vehicle operating conditions. By monitoring accelerator pedal position, vehicle speed, and mode status, the system determines when to maintain the current gear ratio versus when to allow shifts, thereby balancing efficiency optimization with comfort preservation.
2Use of energy by moving object
If the transmission shifts during mode transitions from hybrid to electric, then the engine speed can be optimized, but unexpected gear shifts occur during steady-speed cruising that reduce occupant comfort
Solution Approach 1:
The transmission control strategy dynamically adapts to the operating mode. During hybrid mode transitions, the transmission may shift to optimize engine operation, but during electric mode steady-speed cruising, the system dynamically maintains the current gear ratio to eliminate unexpected shifts and improve comfort.
Solution Approach 2:
The controller monitors vehicle conditions including mode status, vehicle speed, and accelerator pedal position to autonomously determine when shifting is appropriate. The system self-regulates by preventing shifts during steady-speed electric mode operation while allowing shifts during hybrid mode transitions when efficiency optimization is beneficial.
3Loss of energy
If the transmission frequently shifts to optimize engine operation, then fuel efficiency improves, but the frequency of torque variations and engine sound changes increases
Solution Approach 1:
The system selectively changes the gear ratio parameter based on mode transitions and vehicle operating conditions. By introducing conditional logic that considers mode status, vehicle speed, and accelerator pedal position, the system optimizes fuel efficiency through strategic shifting while minimizing torque variations by preventing unnecessary shifts during steady-state operation.
Data Source
AI summary
A vehicle and a method of controlling a powertrain are provided. The vehicle may include a controller programmed to operate a powertrain in a hybrid mode. The controller may be further programmed to, responsive to a request to operate the powertrain in electric mode, transition powertrain operation from the hybrid mode to the electric mode without shifting gears until a change in accelerator pedal position exceeds a threshold following the transition.