Hybrid Powertrain Gear Control for Downhill Retarding Limits
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Solution Overview
Problem
Existing hybrid vehicle controllers fail to account for dynamic variables that affect retarding capability, particularly in steep terrain conditions, leading to potential run-away situations.
Innovation Solution
A controller determines an appropriate gear for the hybrid powertrain based on retarding capability, considering factors like battery state of charge, vehicle weight, rolling resistance, and terrain slope, integrating motor-generator unit and engine braking to manage retarding forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the controller uses limited inputs to determine gear selection, then the device complexity is reduced, but the reliability of preventing run-away conditions deteriorates
Solution Approach 1:
The controller dynamically adjusts gear selection based on real-time retarding capability assessments that incorporate multiple variables including battery state of charge, vehicle weight, rolling resistance, and terrain slope. This dynamic adaptation allows the system to maintain high reliability across varying operating conditions without requiring excessive controller complexity
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring retarding capability parameters and using this information to adjust gear selection decisions. The controller receives feedback from sensors measuring battery state of charge, vehicle dynamics, and terrain conditions, then adjusts gear selection to optimize run-away prevention while managing system complexity
2Reliability
If the controller considers multiple dynamic variables for gear selection, then the reliability of run-away prevention is improved, but the device complexity increases
Solution Approach 1:
The controller segments the gear selection decision-making process into distinct functional modules: retarding capability calculation (incorporating battery state of charge, vehicle weight, rolling resistance), terrain analysis (slope determination), and gear selection logic. This segmentation allows complex multi-variable processing to be managed through organized, manageable subsystems
Solution Approach 2:
The controller is designed as a multi-functional device that simultaneously performs retarding capability assessment, terrain analysis, gear selection, and battery management functions. By consolidating these functions into a single universal controller rather than separate dedicated systems, the patent manages complexity while maintaining comprehensive run-away prevention capabilities
3Force
If the motor-generator unit provides additional retarding force, then the retarding capability is improved, but the battery state of charge increases which may lead to overcharging
Solution Approach 1:
The controller dynamically changes operational parameters by adjusting the motor-generator unit's retarding force output based on real-time battery state of charge levels. When the battery approaches full charge, the controller reduces or discontinues regenerative braking to prevent overcharging, while maintaining adequate retarding capability through engine braking and gear selection
Solution Approach 2:
The system dynamically balances retarding force requirements against battery charge acceptance capacity. The motor-generator unit's retarding contribution is continuously adjusted based on battery state of charge, vehicle speed, and terrain conditions, creating a dynamic equilibrium between utilizing regenerative braking for retarding while preventing battery overcharging
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
Enhances safety and control of hybrid vehicles by dynamically adjusting gear selection to maintain speed and prevent overcharging, thereby preventing unsafe conditions and potential run-aways.
Implementation Method 1
A hybrid vehicle may use a controller to determine an appropriate gear in consideration of the retarding force provided by the entire hybrid powertrain
Implementation Method 2
a battery electrically connected to the motor-generator unit
Implementation Method 3
a transmission engageably connected to the engine and the motor-generator unit, the transmission having a plurality of gears
Implementation Method 4
an engine for providing a second portion of power by consuming fuel
Data Source
AI summary
A system and method of operating a hybrid vehicle having a hybrid powertrain including a motor-generator unit, a battery electrically connected to the motor-generator unit, an engine, and a transmission engageably connected to the engine and the motor-generator unit, the transmission having a plurality of gears. The hybrid vehicle also includes a controller for controlling the hybrid powertrain. The controller is configured to determine a gear for the hybrid vehicle based on a retarding capability of the hybrid powertrain and a grade or slope of a terrain. The retarding capability is based on a state of charge of the battery and at least one of a weight of the hybrid vehicle or a rolling resistance of the hybrid vehicle.