Hybrid Vehicle Towing Control with Anticipatory Engine Start
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Solution Overview
Problem
Hybrid vehicles face delays and driveline disturbances when towing due to the engine starting or restarting, which can exceed the electrical capability of the electric machine, affecting fuel efficiency and user expectations.
Innovation Solution
Implementing a control method that automatically stops the engine when vehicle power demand drops below electrical power and starts it earlier than usual to reduce delay and increase available power for towing, using a controller to manage engine torque based on trailer weight and vehicle loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine is started or restarted during vehicle operation to meet power demand while towing, then the vehicle power availability increases, but driveline disturbances occur and time delay increases
Solution Approach 1:
The controller anticipates power demand increases by monitoring vehicle operating conditions (accelerator pedal position, vehicle speed, battery state of charge) and starts the engine before the power demand actually occurs. This preliminary action prevents driveline disturbances by ensuring the engine is already running when power is needed, eliminating the delay associated with starting the engine on-demand.
2Power
If the engine is operated continuously to meet power demand while towing, then power availability is sufficient, but fuel consumption increases
Solution Approach 1:
The system dynamically adjusts engine operation based on real-time monitoring of vehicle conditions including accelerator pedal position, vehicle speed, battery state of charge, and ambient temperature. The engine operates in electric-only mode when conditions permit (reducing fuel consumption) and transitions to engine operation when power demand requires, optimizing the balance between power availability and fuel efficiency.
Solution Approach 2:
The controller periodically evaluates vehicle operating conditions and determines whether engine operation is necessary. Instead of continuous operation, the engine is cycled on and off based on whether electrical power alone can meet vehicle demands, reducing overall fuel consumption while maintaining adequate power availability when needed.
3Loss of energy
If the electric machine operates alone to propel the vehicle while towing, then fuel efficiency improves, but acceleration capability is reduced due to added trailer weight
Solution Approach 1:
The controller continuously monitors vehicle acceleration performance, battery state of charge, and power demand signals. When the vehicle is towing and acceleration capability becomes insufficient (detected through monitoring actual vs. demanded acceleration), the controller activates the engine to provide additional power, ensuring acceleration capability is maintained while minimizing fuel consumption during steady-state operation.
Data Source
AI summary
A method for controlling a hybrid vehicle having a trailer hitch includes detecting the trailer hitch being in use, commanding an engine to stop, and commanding the engine to start in response to a torque to accelerate being within a predetermined offset below an unladen vehicle torque pull up schedule.