Dual Planetary Gearset EV Drive Unit for Smooth Gear Shifting
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Solution Overview
Problem
Existing electric drive units lack efficient mechanisms for transitioning between high and low gear states, which affects torque output and operational efficiency.
Innovation Solution
The electric drive unit incorporates a dual planetary gearset system with a first and second planetary gearset, a shifter, and connector structures to facilitate smooth transitions between high and low gear states, ensuring optimal torque output and rotational stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single planetary gearset is used in existing electric drive units, then the structure is simpler, but the torque output and gear state transitions are less efficient
Solution Approach 1:
The transmission system is divided into two separate planetary gearsets (first and second planetary gearsets) with distinct functions. The first planetary gearset handles high gear state operations while the second planetary gearset handles low gear state operations, allowing each gearset to be optimized for its specific function and enabling efficient torque management across different operating conditions
Solution Approach 2:
The system dynamically switches between different gear states by selectively engaging or disengaging connections between the two planetary gearsets through the shifter mechanism. This allows the transmission system to adapt its configuration based on torque demands and operating conditions, optimizing performance for either high-speed/low-torque or low-speed/high-torque requirements
2Reliability
If gear state transitions are not efficiently managed, then torque output is reduced, but existing mechanisms lack the necessary components for smooth transitions
Solution Approach 1:
A shifter mechanism acts as an intermediary component that selectively connects or disconnects the input shaft, output shaft, and the two planetary gearsets. This intermediary mechanism enables smooth transitions between high and low gear states by controlling which gearset is actively engaged, ensuring continuous and reliable torque transmission without abrupt interruptions
Solution Approach 2:
The first carrier structure serves multiple functions: it acts as a torque transmission path in the high gear state, provides a connection point for the shifter mechanism, and serves as a structural support element. This multi-functionality reduces the need for separate dedicated components for each function, managing complexity while ensuring reliable gear state transitions
Data Source
AI summary
An electric drive unit includes a motor that rotates a rotor shaft about an axis and first and second planetary gearsets. The first gearset includes a sun gear, planet gears, a ring gear, and a carrier structure. The second gearset is coupled with the first gearset. During rotation of the shaft in a first direction in a high gear state, the sun gear rotates about the axis, planet gears rotate about planet gear axes and revolve about the axis, carrier structure rotates about the axis, and ring gear is substantially stationary relative to the axis. During rotation of the shaft in the first direction in a low gear state, the sun gear rotates about the axis, planet gears rotate about planet gear axes and revolve about the axis, carrier structure rotates about the axis, and ring gear rotates about the axis in a second direction opposite the first direction.