Hybrid Powertrain Engine Speed Control for Fuel Economy
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Solution Overview
Problem
Hybrid electric vehicles face inefficiencies in fuel economy, particularly in Eco-Mode, where existing engine speed control strategies can lead to inefficient engine operation at maximum speed, regardless of accelerator pedal position, and fail to optimize powertrain control for reduced fuel consumption.
Innovation Solution
A method and system for controlling a vehicle powertrain that adjusts engine speed based on accelerator pedal position and battery discharge limit, using different engine speed controls to limit or exceed predetermined speeds depending on the battery's discharge state, thereby optimizing engine operation for improved fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine speed control strategy allows the engine to operate at or near maximum allowable speed to deliver maximum power at wide open pedal position, then power delivery is improved, but fuel economy deteriorates
Solution Approach 1:
The patent implements dynamic engine speed control that adapts to battery state. When battery discharge limit is sufficient, the engine speed is limited to a predetermined value regardless of accelerator pedal position, preventing operation at maximum speed and improving fuel economy. When battery discharge limit is insufficient, the engine speed control is relaxed to allow maximum power delivery. This dynamic adjustment resolves the contradiction between power delivery and fuel economy based on real-time battery conditions.
Solution Approach 2:
The patent changes the engine speed control parameter based on battery discharge limit conditions. By monitoring the battery discharge limit and adjusting the engine speed limit accordingly, the system optimizes fuel economy when battery capacity allows while maintaining power delivery capability when battery capacity is constrained, resolving the trade-off between these two parameters.
2Power
If the engine operates at very inefficient points near maximum speed in Eco-Mode, then power availability is improved, but fuel consumption increases
Solution Approach 1:
The patent applies dynamic engine speed limiting in Eco-Mode based on battery discharge limit. When battery discharge limit is at least the predetermined value, the engine speed is limited to the predetermined speed even in Eco-Mode, preventing operation at inefficient high-speed points and reducing fuel consumption. When battery discharge limit is below the predetermined value, the engine speed control is relaxed to maintain power availability. This dynamic approach resolves the contradiction specific to Eco-Mode operation.
Data Source
AI summary
A system and method for controlling a powertrain in a vehicle includes controlling a speed of an engine in the vehicle using a first engine speed control when an accelerator pedal position is less than a first predetermined position and a battery discharge limit of a battery in the vehicle is at least a predetermined discharge limit. The speed of the engine is controlled using a second engine speed control different from the first engine speed control when the accelerator pedal position is less than the first predetermined position and the battery discharge limit is less than the predetermined discharge limit.