Hybrid DCT Planetary Gear Integration
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Solution Overview
Problem
Dual clutch transmissions (DCTs) in hybrid electric vehicles face challenges with high clutch wear, energy loss, and shift shock, particularly during vehicle starting and on inclines, while also requiring complex control systems to manage heat capacity effectively.
Innovation Solution
A power transmission apparatus is developed that incorporates a single or dual motor/generator and a planetary gear set within a DCT structure using multiple synchronizers, allowing for multiple fixed speed stages with reduced internal components, improved weight minimization, and enhanced fuel efficiency by combining engine and motor/generator rotation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dual clutch transmission (DCT) is used in a hybrid electric vehicle, then efficiency and convenience are improved through alternating activation of odd and even stages, but clutch wear and energy loss increase during vehicle starting and on inclines
Solution Approach 1:
The patent combines a planetary gear set with the dual clutch transmission structure, merging the advantages of both systems. The planetary gear set provides continuous torque transmission and mechanical advantage, reducing the reliance on clutch slippage during starting and incline operations, thereby reducing clutch energy loss while maintaining transmission efficiency.
Solution Approach 2:
The planetary gear set acts as an intermediary mechanism between the engine and the dual clutch transmission. It provides a mechanical advantage that reduces the torque demand on the clutches during high-load conditions such as vehicle starting and incline climbing, thereby reducing clutch wear and energy loss.
2Stability of the object's composition
If a dual clutch transmission (DCT) is used in a hybrid electric vehicle, then continuity in torque transmission is improved through alternating operation of two clutches, but shift shock increases due to short shift-control period
Solution Approach 1:
The planetary gear set is merged with the DCT structure to provide additional torque transmission paths. During shift operations, the planetary gear set can maintain torque transmission while the clutches engage and disengage, reducing the perception of shift shock while maintaining torque continuity.
Solution Approach 2:
The planetary gear set provides a mechanical cushioning effect during shift operations. Its inherent mechanical advantage and torque distribution capabilities help to smooth out the torque fluctuations that occur during clutch engagement and disengagement, reducing shift shock before it reaches the drivetrain.
3Device complexity
If one planetary gear set is added to a DCT structure using three synchronizers, then multiple fixed speed stages are achieved with reduced internal components, but device complexity increases
Solution Approach 1:
The planetary gear set serves multiple functions within the transmission system: it provides additional fixed speed stages, enables torque assistance from the motor/generator, and contributes to weight reduction by allowing the elimination of certain synchronizers. This multi-functionality justifies the added complexity by delivering multiple benefits from a single added component.
Solution Approach 2:
The planetary gear set is integrated with the existing DCT structure and synchronizer system, merging its functions with the overall transmission operation. This integration allows the planetary gear set to contribute to multiple speed stages and torque management functions simultaneously, maximizing its utility despite the increase in device complexity.
4Adaptability or versatility
If a motor/generator is added to a DCT structure, then electric vehicle mode and hybrid electric vehicle mode are enabled, but weight increases
Solution Approach 1:
The motor/generator is designed to perform multiple functions: it acts as a motor during electric vehicle mode, as a generator during regenerative braking, and provides torque assistance during hybrid electric vehicle mode. This multi-functionality maximizes the utility of the added component, justifying the weight increase by enabling versatile driving modes and improving overall vehicle efficiency.
Solution Approach 2:
The motor/generator is integrated with the planetary gear set and DCT structure, merging its functions with the existing transmission system. This integration allows for compact packaging and shared components, minimizing the weight penalty of adding the motor/generator while maximizing its functional benefits across multiple driving modes.
Data Source
AI summary
A power transmission apparatus may include engine; first motor/generator; first rotation element fixed to the engine, second rotation element fixed to the first motor/generator, and third rotation element; first input shaft selectively connectable to the third rotation element; second input shaft selectively connectable to the third rotation element; third input shaft; an output shaft; an idle shaft operably connected to the second input shaft and the third input shaft; and speed stage module including drive gears rotatably disposed on the first input shaft, the third input shaft, or the idle shaft, driven gears meshed with the drive gears and fixed on the output shaft, and power delivery gears and an idle gear fixed on the second input shaft, the third input shaft, or the idle shaft, and synchronizers selectively connecting at least one among the drive gears to the first input shaft, the third input shaft, or the idle shaft.