Hybrid Transmission Synchronous Shift Between Series and Compound-Split Modes
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Solution Overview
Problem
Hybrid powertrains for vehicles require additional components like motor/generators, brakes, and clutches, increasing vehicle cost and packaging space, while existing shifting methods between operating modes can lead to mechanical losses due to slipping and complex clutch control algorithms.
Innovation Solution
A hybrid transmission with a series mode and compound-split mode, utilizing three planetary gear sets and two torque-transmitting mechanisms, allows for synchronous shifting without slipping, minimizing electrical losses by enabling efficient power transfer through a fixed gear ratio, and simplifying clutch control by eliminating the need for feedback on clutch engagement and disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hybrid powertrains use additional components like motor/generators, brakes, and clutches to enable different operating modes, then fuel economy is improved, but vehicle cost and packaging space requirements increase
Solution Approach 1:
The patent combines the series mode and compound-split mode operating capabilities into a single hybrid transmission system that shares common components (planetary gear sets, motor/generators, torque-transmitting mechanisms). This merging allows the system to achieve multiple operating modes without requiring separate complete powertrain systems for each mode, thereby improving fuel economy while controlling vehicle cost and packaging space.
2Adaptability or versatility
If existing shifting methods between operating modes are used, then mode switching is achieved, but mechanical losses occur due to slipping and complex clutch control algorithms are required
Solution Approach 1:
The patent uses the controller to preemptively manage the engagement and disengagement of torque-transmitting mechanisms during mode transitions. By controlling the timing and sequence of clutch engagement before actual mode switching occurs, the system minimizes slipping and mechanical losses while simplifying the control algorithm through predetermined shift strategies.
Solution Approach 2:
The torque-transmitting mechanisms (clutches) serve as intermediaries between the different operating modes. The controller acts as an intermediary that coordinates the engagement/disengagement of these clutches to enable smooth transitions between series and compound-split modes, reducing direct mechanical conflict and energy loss during shifting.
3Adaptability or versatility
If existing shifting methods between operating modes are used, then mode switching is achieved, but complex clutch control algorithms with feedback requirements are needed
Solution Approach 1:
The hybrid transmission system incorporates self-service features through the controller that automatically manages clutch engagement and disengagement based on predetermined criteria and sensor feedback from the transmission system itself. This self-managed control reduces the need for complex external control algorithms and feedback loops, simplifying the overall control system while maintaining adaptability for mode switching.
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
The solution enables seamless mode switching between series and compound-split modes, reducing mechanical losses and simplifying clutch control, thereby improving fuel efficiency and reducing vehicle costs by minimizing electrical losses and packaging requirements.
Implementation Method 1
A first, a second, and a third planetary gear set, each having a first, a second, and a third member
Implementation Method 2
A first of the torque-transmitting mechanisms is engaged to establish a hybrid series operating mode; A second of the torque-transmitting mechanisms is engaged to establish a compound-split operating mode
Data Source
AI summary
A hybrid transmission is provided that has both a hybrid series operating mode and a compound-split operating mode. The transmission includes an input member operatively connected with the engine, an output member, and a plurality of selectively engageable torque-transmitting mechanisms. A gearing arrangement and first and second motor/generators operatively connected with the gearing arrangement are also provided. The gearing arrangement includes a first, a second, and a third planetary gear set, each having a first, a second, and a third member. A first interconnecting member connects a respective one of the members of each of the planetary gear sets for common rotation with one another. A second interconnecting member connects another one of the members of one of the planetary gear sets for common rotation with another one of the members of another of the planetary gear sets.