Planetary EV Transmission Layout for Efficient Gear Shifting
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Solution Overview
Problem
Current motor vehicle transmissions for electric and hybrid vehicles face inefficiencies in gear engagement and power flow, particularly in achieving high efficiency across multiple gears with a compact structure.
Innovation Solution
A motor vehicle transmission design incorporating two planetary gearsets with specific shifting elements that allow for rotational fixed connections between key elements, enabling efficient power flow through selective gear engagement and decoupling, thereby achieving high efficiency in at least one gear and supporting traction force during gearshifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gearsets are used to achieve multiple gears, then gear versatility is improved, but device complexity increases
Solution Approach 1:
The transmission is divided into two independent planetary gearsets (first and second planetary gearsets), each capable of providing gear reduction. By segmenting the power flow into separate planetary stages with independent shifting elements, the system achieves multiple gear ratios while maintaining modularity and reducing overall complexity compared to a single complex planetary system.
Solution Approach 2:
The first and second planetary gearsets are arranged in a nested or串联 configuration where the output of the first planetary gearset feeds into the second planetary gearset. This nesting allows multiple gear ratios to be achieved through sequential reduction stages, compactly integrating multiple functions into a unified transmission structure.
2Adaptability or versatility
If shifting elements are added to enable gear changes, then gear adaptability is improved, but device complexity increases
Solution Approach 1:
The shifting function is extracted and dedicated to specific shifting elements (first shifting element for the first planetary gearset, second shifting element for the second planetary gearset). Each shifting element independently controls the engagement state of its corresponding planetary gearset, simplifying the control logic and reducing the complexity of the shifting mechanism by assigning specific functions to specific components.
Solution Approach 2:
The shifting elements dynamically adjust the engagement state of the planetary gearsets during operation, enabling smooth transitions between different gear ratios. The system can selectively engage or disengage each planetary gearset based on driving conditions, providing adaptive gear changing without requiring complex mechanical shifters.
3Loss of energy
If rotational fixed connections are implemented between planetary elements, then power flow efficiency is improved, but device flexibility decreases
Solution Approach 1:
The third element of the first planetary gearset and the second element of the second planetary gearset are connected through a rotationally fixed connection that acts as an intermediary power flow path. This fixed connection ensures efficient torque transmission between the two planetary stages while the shifting elements maintain flexibility by allowing selective disengagement of each planetary gearset when needed.
Data Source
AI summary
A motor vehicle transmission (1) has a drive input shaft (15), a drive output shaft (16), a first planetary gearset (P1), and a second planetary gearset (P2). The drive input shaft (15) is provided for coupling to a drive machine. In addition, a first shifting element (A) and a second shifting element (B) are provided, at least functionally. Also disclosed is a drive unit (5), a motor vehicle drivetrain, a hybrid or electric vehicle, and a method for operating a motor vehicle transmission.