Hybrid Powertrain Torque Management for Off-Road Response
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Solution Overview
Problem
Hybrid vehicles with smaller displacement engines face challenges in providing immediate torque during off-road conditions, leading to delayed power delivery and increased fuel consumption during on-road conditions due to the need for significant engine spin-up.
Innovation Solution
A powertrain operating method that adjusts engine power output based on time-averaged transmission input power, allowing the engine to maintain a base power level while an electric machine provides additional power to meet driver demand, thereby reducing engine power changes and minimizing delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large displacement engine is installed to provide significant torque during off-road conditions, then torque availability is improved, but fuel consumption increases during on-road conditions
Solution Approach 1:
The power delivery function is segmented between the engine and electric machine. The engine provides base power at steady-state operating points, while the electric machine handles transient power demands during off-road conditions. This segmentation allows the engine to operate efficiently during on-road conditions without requiring large displacement, while still meeting peak torque demands during off-road conditions through coordinated engine-electric machine operation.
2Power
If the rotational speed of a smaller displacement turbocharged engine is increased to provide significant torque during off-road conditions, then torque output is improved, but powertrain response time is delayed due to engine spin-up time
Solution Approach 1:
The engine is pre-positioned at or near the optimal operating point before transient off-road conditions occur. The controller anticipates the need for increased torque and adjusts engine operating parameters in advance, so that when the driver demands power during off-road conditions, the engine is already configured to deliver torque immediately without spin-up delay. The electric machine provides supplemental power during the transition period.
Solution Approach 2:
The electric machine acts as an intermediary between the engine and the drivetrain during transient conditions. When rapid torque delivery is needed, the electric machine immediately supplements engine output, bridging the gap until the engine can fully respond. This intermediary capability eliminates the perceived delay that would otherwise occur during engine spin-up.
3Speed
If engine power changes rapidly to meet sudden driver demand during off-road conditions, then power responsiveness is improved, but power delivery consistency deteriorates
Solution Approach 1:
The control system dynamically adjusts the division of labor between engine and electric machine based on real-time operating conditions. During transient off-road conditions, the electric machine dynamically supplements engine power to maintain consistency. The controller continuously monitors driver demand, vehicle state, and component capabilities, dynamically repositioning the engine operating point while using the electric machine to smooth out transitions and maintain consistent power delivery to the drivetrain.
Data Source
AI summary
Systems and methods for operating a hybrid powertrain or driveline that includes an engine and an integrated starter/generator are described. In one example, engine power is adjusted based on a time averaged transmission input shaft power so that the engine may operate in a power region where its performance is enhanced to support operation in an off-road environment.