Hybrid Powertrain with Variable Displacement Engine and Late Intake Valve
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Solution Overview
Problem
Existing hybrid powertrain systems face inefficiencies in achieving high-average power and continuous, constant speed operation, especially in high-speed duty cycles and steep grades, due to limitations in series and parallel hybrid transmission configurations.
Innovation Solution
A hybrid powertrain with a two-mode, compound-split, electromechanical transmission system that includes a variable displacement internal combustion engine with selectively deactivatable intake and exhaust valves and a late intake valve closing method, combined with an electrically variable transmission using planetary gear sets and motor/generators to optimize power transfer and reduce pumping losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a series hybrid transmission configuration is used, then fuel economy is improved and emissions are reduced, but the system cannot accommodate high-average power vehicles or sustain continuous constant speed operation at high speeds
Solution Approach 1:
The transmission system is designed to operate in multiple modes (series mode, parallel mode, and direct drive mode) allowing it to function effectively across a wide range of power and speed requirements. The same transmission hardware can adapt to both fuel-efficient low-power operation and high-power sustained operation through mode switching controlled by the power control device.
Solution Approach 2:
The transmission employs variable ratio mechanisms including planetary gear sets and torquesqueezing mechanisms that can dynamically adjust gear ratios and power flow paths based on operating conditions. This dynamic adaptability allows the system to optimize for fuel economy at low speeds while maintaining capability for high-speed sustained operation.
2Productivity
If a typical series hybrid transmission configuration is used, then low-average power duty cycles are optimized, but high-speed duty cycles and steep grades cannot be achieved at desired high efficiencies
Solution Approach 1:
The transmission system integrates series and parallel hybrid capabilities within a single configuration, enabling it to handle both low-average power duty cycles optimized for fuel economy and high-speed duty cycles requiring sustained power output. The power control device selects appropriate operational modes based on demand.
Solution Approach 2:
The transmission is divided into distinct functional sections including planetary gear sets, torquesqueezing mechanisms, and electric motor/generator units that can operate semi-independently. This segmentation allows different parts of the system to be optimized for different operating regimes while working together as an integrated whole.
3Object-generated harmful factors
If auxiliary power units of relatively low power are used, then emissions are minimized and fuel economy is improved, but the system does not accommodate high-average power vehicles
Solution Approach 1:
The transmission system can operate in series mode with the auxiliary power unit for fuel-efficient low-emission operation, and switch to parallel mode where the auxiliary power unit combines with direct engine power to deliver high power output when needed, all through the same transmission hardware.
Solution Approach 2:
The system merges the output of the auxiliary power unit with direct engine power output through the planetary gear sets and torquesqueezing mechanisms. This combining allows the low-power auxiliary unit to contribute to emissions reduction during normal operation while still achieving high power capability when both power sources are combined.
4Device complexity
If a fixed ratio transmission is used, then mechanical simplicity is maintained, but the system cannot provide seamless transitions between operating modes or optimize efficiency across wide operating conditions
Solution Approach 1:
The transmission incorporates variable ratio mechanisms including planetary gear sets and torquesqueezing mechanisms that can continuously or steplessly adjust gear ratios based on operating conditions. This dynamic ratio adjustment enables seamless transitions between operating modes and optimization of efficiency across the full operating range.
Solution Approach 2:
The transmission system employs periodic switching between different operational modes (series mode, parallel mode, direct drive mode) controlled by the power control device based on real-time operating conditions. This periodic mode switching allows the system to continuously optimize for efficiency while maintaining mechanical simplicity through standardized components.
Data Source
AI summary
A hybrid powertrain includes an electrically variable transmission and an internal combustion engine. The transmission is operable to provide a continuously variable mode of operation. The engine is capable of variable displacement in that at least half of the cylinders contained therein are deactivatable. Additionally the internal combustion engine operates with a late intake valve closing strategy to increase the peak efficiency of the internal combustion engine.