Electro-Mechanical Transmission Control Optimizing Input Speed
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Solution Overview
Problem
Existing powertrain control systems for electro-mechanical transmissions face challenges in efficiently managing torque and rotational speed across various operating range states, leading to suboptimal fuel economy, emissions, and frequent shifting, particularly in response to changing road conditions and operator torque demands.
Innovation Solution
A method that determines the current and potential transmission operating range states and engine states, calculates preferred input speeds with associated power inputs and losses, applies biasing costs to lower input speeds, and weights preferability factors to selectively change the operating states based on operator torque requests and system conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transmission control system frequently shifts between operating range states in response to changing road conditions and operator torque demands, then the system adapts quickly to varying conditions, but fuel economy deteriorates and emissions increase due to suboptimal torque management
Solution Approach 1:
The control system pre-calculates and stores optimal input speeds and associated power losses for each potential transmission operating range state before actual shifting occurs. This preliminary preparation allows the system to execute shifts with optimized torque management, avoiding the energy-wasting trial-and-error approach of conventional systems that react to conditions without pre-planned optimization strategies.
Solution Approach 2:
The system dynamically adjusts operating range state selection and input speed optimization based on real-time conditions including road conditions and operator torque demands. The control system continuously evaluates multiple potential states and selectively commands changes based on preferability factors, enabling adaptive optimization that responds to changing conditions while maintaining fuel efficiency through intelligent state selection rather than frequent arbitrary shifts.
2Device complexity
If the transmission control system uses a simple control algorithm, then the system complexity is reduced, but the precision of torque management deteriorates leading to suboptimal fuel economy and frequent shifting
Solution Approach 1:
The control algorithm segments the transmission operating space into distinct operating range states with specific characteristics. By dividing the continuous operating space into discrete states (each with defined minimum input speeds and associated power losses), the system achieves precise torque management through state-based control rather than continuous complex calculations. This segmentation allows the controller to select from predefined optimal states based on preferability factors, maintaining precision while managing complexity.
3Adaptability or versatility
If the transmission operates without biasing costs for lower input speeds, then the system has greater operational flexibility, but power losses increase due to suboptimal input speed selection
Solution Approach 1:
The control system modifies the cost function parameters by introducing biasing costs that vary with input speed magnitude. This parameter change transforms the optimization criterion from purely power-loss-based to a composite metric that incorporates both power losses and biasing costs. The biasing cost magnitude is proportional to the difference between selected input speed and minimum input speed for each state, guiding the system to prefer operating points that minimize power losses while maintaining operational flexibility through selective state transitions based on overall preferability factors.
Data Source
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AI summary
A powertrain system includes an engine (14) mechanically coupled to an electro-mechanical transmission (10) at an input (12) thereto selectively operative in one of a plurality of transmission operating range states and one of a plurality of engine states. A method for controlling the powertrain system includes combining sets of preferability factors inputted from engine sensors in a microprocessor or computer with other preferability factors generated during engine (14) and vehicle operation to provide an output for a transmission control module (17), which may execute an operating range or engine state change.