Hybrid Engine Spinning for Extended Electric Speed
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Solution Overview
Problem
Hybrid electric vehicle systems face limitations in maximum attainable vehicle speed during electric-only mode due to mechanically-imposed speed constraints, leading to increased battery usage and potential mechanical degradation of transmission components, which degrades the operator's experience and affects fuel economy.
Innovation Solution
The system allows vehicle speed to be increased by spinning the engine unfueled during electric-only mode, adjusting cylinder valve operation to reduce airflow and parasitic losses, while maintaining rotational speed of transmission components within safe limits, thereby prolonging battery operation and improving fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is spun unfueled to increase vehicle speed above threshold, then the maximum attainable vehicle speed is improved, but engine parasitic losses increase
Solution Approach 1:
The system changes the operational parameters of the engine by spinning it at different speeds unfueled. By adjusting the engine speed parameter, the system can optimize the balance between achieving higher vehicle speeds and minimizing parasitic losses, as different engine speeds create different levels of drag and energy consumption.
Solution Approach 2:
The system dynamically adjusts engine operation based on real-time conditions. The controller monitors vehicle speed, battery state of charge, and transmission component speeds, then dynamically decides when to spin the engine unfueled and at what speed, making the system adaptable to changing operational requirements rather than using a fixed approach.
2Speed
If the engine is spun unfueled to raise vehicle speed, then the maximum vehicle speed is improved, but battery usage increases
Solution Approach 1:
The system incorporates feedback mechanisms where the controller continuously monitors the state of charge of the battery and adjusts engine spinning operations accordingly. When battery charge is high, the system can afford to spin the engine unfueled more aggressively to achieve higher speeds. When battery charge is low, the system limits or avoids engine spinning to preserve battery energy, creating a closed-loop control system that optimizes energy utilization.
Solution Approach 2:
The system changes operational parameters based on battery state. By adjusting engine speed, vehicle speed limits, and transmission component speed limits according to the battery's state of charge, the system optimizes the trade-off between achieving high vehicle speeds and preserving battery energy for essential functions.
3Reliability
If the rotational speed of transmission components is limited to protect from damage, then component reliability is improved, but the maximum vehicle speed is reduced
Solution Approach 1:
The spinning unfueled engine acts as an intermediary mechanism between the battery and the transmission components. By coupling the engine to the transmission through the planetary gear system, the engine serves as a buffer that can absorb excess rotational energy and prevent transmission components from exceeding their speed limits, while still allowing the vehicle to achieve higher speeds through the engine's direct connection to the drivetrain.
Solution Approach 2:
The engine serves multiple functions simultaneously: it acts as a propulsion source when fueled, a speed-limited protective element when spinning unfueled, and a variable resistance element when operated at different unfueled speeds. This multi-functionality allows the same component to address both the need for high vehicle speeds and the need to protect transmission components from overspeed damage.
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
This approach enables higher vehicle speeds in electric mode with reduced engine pumping losses, prolonged battery operation, and improved fuel economy by minimizing mechanical degradation of transmission components.
Implementation Method 1
the position of a cam phaser may be adjusted to reduce airflow through the spinning engine. This may enable the operation of a cylinder valve (e.g., for an intake valve and/or an exhaust valve) to be adjusted. For example, a valve timing may be advanced or retarded, as appropriate, to reduce an airflow through the spinning engine.
Data Source
AI summary
Methods and systems are provided for raising the speed of a hybrid electric vehicle operating in an electric-only mode. During conditions when the vehicle is driven only by an electric motor, vehicle speed may be raised by spinning the engine unfueled using power from a system battery, while adjusting valve operation to reduce engine pumping losses. In this way, vehicle speed may be raised more efficiently and without damaging rotating transmission components.