Hybrid Engine Torque Control for Neutral-State Battery Charging
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Solution Overview
Problem
Hybrid vehicles with power split transmissions face issues when the shifter is in neutral position, leading to unintended vehicle motion and battery charge depletion, as the engine cannot be intentionally started or used to charge the battery, causing frustration for drivers.
Innovation Solution
A method where the engine torque is adjusted based on actual braking torque when the transmission is in neutral, allowing the engine to provide torque for battery charging and prevent unintended motion, by operating in a torque control mode to hold the vehicle stationary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is intentionally stopped or started when the shifter is in neutral position to reduce unintended vehicle motion, then vehicle safety is improved, but the battery cannot be charged and electrical loads may deplete battery charge
Solution Approach 1:
The engine control mode dynamically switches between speed control mode and torque control mode based on the shifter position and braking conditions. When the shifter is in neutral and braking torque exceeds the threshold, the system transitions to torque control mode, allowing the engine to provide charging torque while maintaining vehicle stationary status.
Solution Approach 2:
The system changes the engine torque parameter from zero (in traditional neutral operation) to a controlled positive value in torque control mode. This parameter change enables the engine to generate torque for battery charging while the vehicle remains stationary, resolving the contradiction between safety and energy management.
2Ease of operation
If the engine operates in speed control mode when shifter is in neutral, then unintended vehicle motion is prevented, but battery charging capability is lost
Solution Approach 1:
The control system dynamically adjusts engine operating parameters based on real-time conditions. When braking torque exceeds the threshold in neutral position, the system switches from speed control mode to torque control mode, enabling the engine to generate charging torque while maintaining vehicle stationary status through controlled torque application.
Solution Approach 2:
The engine serves dual purposes: maintaining vehicle stationary status and charging the battery simultaneously. In torque control mode, the engine's torque output is used to drive the generator for battery charging while the controlled torque application prevents unintended vehicle motion, allowing the system to serve itself rather than requiring separate mechanisms.
3Loss of energy
If drivers move shifter to neutral position to reduce engine load and fuel consumption, then fuel efficiency is improved, but battery charge depletes due to inability to charge while in neutral
Solution Approach 1:
The system dynamically adapts engine operation based on shifter position and braking conditions. When in neutral position with sufficient braking torque, the engine transitions to torque control mode where it generates charging torque to replenish battery charge, eliminating the need for drivers to avoid neutral position and preserving natural driving habits while maintaining energy balance.
Solution Approach 2:
The system converts the traditionally harmful condition of engine operation in neutral position (which previously caused battery depletion) into a beneficial state by enabling battery charging. The engine torque that would have been wasted is now utilized to charge the battery, turning a potential problem into an energy recovery opportunity.
Data Source
AI summary
Systems and methods for operating an internal combustion engine that is coupled to a power split transmission are described. In one example, the internal combustion engine is operated in a speed control mode or a torque control mode in response to a braking torque and a transmission shift command. Operating the engine in the torque control mode may allow the engine to charge a battery while a neutral transmission state is selected.