Hybrid Vehicle Park Neutral Engine Control
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Solution Overview
Problem
Hybrid vehicles lack driver control over engine speed and traction battery charging when in PARK or NEUTRAL gear, limiting the ability to rev the engine or shift transmission like conventional vehicles, which can result in reduced drivability and user satisfaction.
Innovation Solution
A vehicle control system with a controller that starts the engine and controls engine torque and speed based on accelerator pedal position, engaging a clutch between the engine and electric machine to charge the battery or rev the engine, while also managing transmission torque converter impeller speed, allowing for increased launch torque and enhanced driver control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the hybrid vehicle automatically controls engine and electric machine operation, then fuel efficiency is improved, but driver control and manual operation capability deteriorate
Solution Approach 1:
The control system dynamically adapts between automatic control mode (for fuel efficiency) and manual control mode (for driver control). The system allows transition between these modes based on driver input, particularly through accelerator pedal position interpretation in PARK or NEUTRAL gears, enabling the driver to request engine starting and control when the automatic system would otherwise keep the engine stopped.
Solution Approach 2:
The system changes operational parameters based on accelerator pedal position. When the pedal is depressed above a threshold in PARK or NEUTRAL, the system interprets this as a driver control request and changes parameters including engine start command, clutch engagement state, and electric machine control mode, thereby providing manual control capability while maintaining automatic control during normal operation.
2Use of energy by moving object
If the engine is automatically started and stopped based on operating conditions, then fuel efficiency is improved, but the ability to rev the engine or charge the battery on demand deteriorates
Solution Approach 1:
The control system uses feedback from the accelerator pedal position sensor to determine driver intent. When the pedal is depressed above a threshold in PARK or NEUTRAL, the system interprets this as a request for engine revving or battery charging and adjusts engine operation accordingly, allowing on-demand engine speed control while maintaining automatic control during normal driving conditions.
Solution Approach 2:
The accelerator pedal serves multiple functions: it controls throttle during normal driving, serves as a control input for engine starting in PARK/NEUTRAL, and acts as a request signal for battery charging. This multi-functionality allows the system to provide versatile engine control capabilities without adding separate control mechanisms.
3Stability of the object's composition
If the transmission is held in PARK or NEUTRAL, then vehicle stability is improved, but the ability to perform neutral drop or drive slam engagement deteriorates
Solution Approach 1:
The system performs preliminary engine starting and clutch engagement preparation when the driver depresses the accelerator pedal in PARK or NEUTRAL. This preliminary action readies the powertrain for subsequent transmission engagement, enabling neutral drop or drive slam maneuvers while maintaining vehicle stability during the preparation phase.
Solution Approach 2:
The clutch serves as an intermediary between the engine and transmission, allowing the driver to control engine speed and prepare the powertrain for transmission engagement while the transmission remains in PARK or NEUTRAL. This intermediary mechanism enables transmission engagement capability without compromising vehicle stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides drivers with additional control over engine speed and traction battery charging, enabling engine revving and transmission shifting with engine speed above idle, improving drivability and user experience by interpreting accelerator pedal position and rate of change to facilitate torque and speed control.
Implementation Method 1
control engine torque responsive to accelerator pedal position exceeding idle position and being below a threshold to drive the electric machine to charge the battery
Data Source
AI summary
A hybrid vehicle control system and method include a controller programmed to, while a transmission is in PARK or NEUTRAL, start an engine, close a disconnect clutch selectively coupling the engine to an electric machine, and control the electric machine to charge a traction battery in response to the accelerator pedal position exceeding an idle position and being less than a threshold. The controller controls transmission impeller speed in response to accelerator pedal position exceeding the threshold to allow revving the engine in response to accelerator pedal. A method for controlling a hybrid vehicle includes starting an engine, closing a clutch between the engine and an electric machine, and controlling the engine and the electric machine to either: i) charge a traction battery or ii) rev the engine based on accelerator pedal position relative to a threshold above an idle position while the transmission is in PARK or NEUTRAL.