Hybrid Vehicle Engine Start Sequence Selection
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Solution Overview
Problem
Hybrid electric vehicles face challenges in efficiently controlling engine start events based on vehicle state and driver demand, particularly when the battery state of charge is low or additional power is required, necessitating a method to seamlessly transition between power sources.
Innovation Solution
A hybrid vehicle system with an engine, electric machine, upstream and downstream clutches, and a controller that selects engine start sequences based on transmission gearbox input speed and driver demand, using a control system to manage the clutches and electric machine to optimize power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is shutdown during inefficient operation to improve fuel economy, then fuel efficiency is improved, but the engine cannot provide power when needed
Solution Approach 1:
The electric motor serves as an intermediary power source that bridges the gap between engine shutdown and power demand. When the engine is turned off to save fuel, the electric motor can immediately provide necessary power, and when additional power is needed beyond the motor's capability, the engine can be restarted quickly. This intermediary system resolves the contradiction by providing flexible power delivery based on real-time demands.
Solution Approach 2:
The system dynamically switches between different power sources (electric motor alone, engine alone, or both combined) based on real-time vehicle conditions, battery state of charge, and power demand. This dynamic adaptation allows the system to optimize fuel efficiency during low-demand periods while ensuring power availability during high-demand periods, resolving the static contradiction between fuel savings and power readiness.
2Use of energy by moving object
If multiple control sequences are used for engine start based on vehicle state, then power delivery is optimized, but the control system complexity increases
Solution Approach 1:
The control system dynamically selects from multiple engine start sequences based on real-time vehicle state parameters including battery state of charge, transmission input speed, and power demand. Rather than using a single fixed control sequence, the system adapts its control strategy to current conditions, optimizing power delivery while managing complexity through rule-based decision logic that responds to measured vehicle parameters.
Data Source
AI summary
A hybrid vehicle has an engine, an electric machine connected to the engine by an upstream clutch, a transmission gearbox connected to the electric machine by a downstream clutch, and a controller. The controller is configured to start the engine using one of a plurality of start sequences that control the electric machine, the upstream and downstream clutches. The engine start sequence is selected based on transmission gearbox input speed and a driver demand input. A method of controlling a hybrid vehicle is provided. An engine is selectively coupled to an electric machine by an upstream clutch with the electric machine selectively coupled to a transmission gearbox by a downstream clutch. The engine is started using a control sequence to control the electric machine, upstream clutch, and downstream clutch. The control sequence is determined by a vehicle state based on transmission gearbox input speed and a driver demand input.