Two-Speed EV Transmission With Single-Actuator Seamless Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric drive systems for vehicles face challenges in achieving seamless and efficient gear shifting between different speed ratios, often resulting in load interruptions and increased complexity due to the need for multiple actuators and complex locking mechanisms.
Innovation Solution
A two-speed transmission system utilizing a single actuator to move a sliding sleeve between gear positions, with synchronized clutches and chamfered teeth for smooth torque transfer, allowing for rapid and load-interruption-free shifting between gear ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple actuators are used for locking both ring gears independently, then the transmission can achieve two different gear ratios, but the device complexity and installation space increase
Solution Approach 1:
A single actuator is designed to perform multiple functions: it can lock the first ring gear in one position, lock the second ring gear in another position, and selectively engage different planetary gear sets to achieve two distinct gear ratios. This multi-functional design eliminates the need for separate actuators for each locking mechanism, thereby reducing device complexity while maintaining gear ratio adaptability
Solution Approach 2:
The locking mechanisms for both ring gears are merged into a single integrated locking device controlled by one actuator. The actuator can selectively position locking elements to engage with either the first or second ring gear, combining what would traditionally require separate actuating systems into a unified mechanism that reduces installation space and component count
2Adaptability or versatility
If conventional locking mechanisms are used for both ring gears, then gear ratio changes are possible, but load interruptions occur during shifting
Solution Approach 1:
Before the actual gear ratio change is completed, the actuator preliminarily positions the locking elements and planetary gear sets to prepare for the transition. This preliminary positioning ensures that the second planetary gear set is pre-aligned and ready to immediately承接 torque transmission when the first gear disengages, thereby preventing load interruptions and maintaining torque continuity throughout the shifting process
Solution Approach 2:
The single actuator serves as an intermediary that coordinates the disengagement of one planetary gear set and the engagement of another. By controlling the timing and sequence of locking element positioning, the actuator mediates the transition between gear ratios in a way that ensures continuous torque transmission through the transmission system, avoiding the load interruptions that would occur with conventional independent locking mechanisms
Data Source
AI summary
A compact and fast-shifting two-speed transmission for an electric drive system, such as an electric vehicle, has two synchronized dog clutches. A sliding sleeve for engaging a first and second gear is actuatable using a single actuator. A substantially load-interruption-free shifting is realized via a friction engagement in the synchronization. A drive system having such a two-speed transmission is capable of achieving at least substantially load-interruption-free shifting.