Planetary Axle Center Transmission With Compact Lubrication Switching
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Solution Overview
Problem
Existing axle center transmissions face challenges in achieving a compact design while ensuring reliable lubrication and cooling, particularly when space is limited for lubricant conveyance, and require flexible gear transmission ratios to accommodate different speed ranges and high-revolution drive devices.
Innovation Solution
The axle center transmission incorporates a transmission gearing with at least two selectively switchable gear ratios and a differential, featuring a planetary transmission design with a stationary planet carrier for simplified lubrication and cooling, and a coupling apparatus for switching between gear ratios, including a 1:1 and stepped-down configurations, to efficiently distribute driving torque to half shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the axle center transmission is designed to be compact, then the space for lubricant conveyance is reduced, but reliable lubrication and cooling become more difficult to achieve
Solution Approach 1:
A lubricant conduit is introduced as an intermediary component to convey lubricant from the stationary planet carrier to the rotating elements (sun gear, planet gears, annulus gear). This mediator enables reliable lubrication in the compact design by providing a dedicated pathway for lubricant delivery without requiring large spaces
Solution Approach 2:
The stationary planet carrier is designed with integrated lubricant conveyance capability, serving its own lubrication function while also supporting the rotating elements. The planet carrier acts as both a structural support and a lubricant distribution system, eliminating the need for separate complex lubrication infrastructure
2Adaptability or versatility
If different gear transmission ratios are implemented to accommodate high-revolution drive devices, then the transmission gearing complexity increases, but the design shape compactness is compromised
Solution Approach 1:
The transmission gearing employs a planetary transmission mechanism that can dynamically change gear ratios through the engagement of different tooth portions of the annulus gear with the planet gears. A switching mechanism allows the annulus gear to engage different segments, providing multiple fixed gear ratios (including 1:1 and stepped-down ratios) without requiring multiple separate gear sets, thus maintaining compactness while achieving adaptability
Solution Approach 2:
The single planetary transmission system performs multiple functions: it can operate in 1:1 direct drive mode, provide stepped-down gear ratios for high-revolution electric motors, and adapt to different driving conditions. The annulus gear's multi-segment design allows one transmission unit to replace what would traditionally require multiple separate gear transmissions
Data Source
AI summary
An axle center transmission for transmitting a driving torque received from a drive device to two half shafts of an axle comprises a transmission gearing for transmitting a driving torque received at an input element and having at least two selectively switchable gear transmission ratios and a differential for distributing the transmitted driving torque to two output elements. The transmission gearing has a first gear formed as a planetary transmission having a first sun gear, a first planet carrier having planet gears, and a first annulus gear. The transmission gearing furthermore has a second gear formed as a planetary transmission having a second sun gear, a second planet carrier having planet gears, and a second annulus gear. The first sun gear forms said input element; the first planet carrier is stationary; and the second sun gear is couplable or coupled to the first annulus gear for a common rotation.