Planetary Transmission Layout With External Locking Mechanisms
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Solution Overview
Problem
The existing transmission arrangements for electrically propelled working machines, such as haulers and excavators, face challenges in adapting to the different speed ranges compared to conventional internal combustion engine vehicles, requiring an improved gearbox design that is energy-efficient and suitable for rough terrain operations.
Innovation Solution
A two-stage transmission arrangement with a first and second planetary gear set, each with a locking mechanism controlled by fluid pressure, allowing for locked, released, and slipping conditions to optimize energy efficiency and facilitate smooth transitions between these states, enabling effective use as a parking brake and service brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional gearbox is used in electrically propelled working machines, then the transmission can handle the required torque, but the gearbox requires lubrication which increases maintenance complexity and energy consumption
Solution Approach 1:
The patent extracts the lubrication system from the transmission arrangement by locating locking mechanisms externally, eliminating the need for internal lubrication and associated maintenance
Solution Approach 2:
The transmission arrangement operates without external lubrication services, with the dry gearbox design being self-sufficient and maintenance-free regarding lubrication
2Reliability
If locking mechanisms are located inside the transmission housing cavity, then the braking function is effective, but the transmission requires lubrication which increases energy consumption and maintenance
Solution Approach 1:
The locking mechanisms are extracted from the transmission housing cavity and located externally, eliminating the need for lubrication while preserving the braking function
Solution Approach 2:
A transmission housing wall assembly acts as an intermediary, providing a barrier between the dry external locking mechanisms and the enclosed transmission components
3Productivity
If a two-stage planetary gear set is used to adapt to electric machine speed ranges, then the transmission efficiency is improved, but the device complexity increases
Solution Approach 1:
The transmission is segmented into two distinct planetary gear stages, each with independent locking mechanisms, allowing optimized gear ratios for electric machine operation
Solution Approach 2:
The first and second planetary gear sets are nested within each other, with the first planet carrier forming part of the second planetary gear set, reducing overall structural complexity
4Reliability
If the transmission housing cavity is sealed to protect internal components, then the reliability is improved, but the locking mechanisms cannot be accessed for maintenance
Solution Approach 1:
The locking mechanisms are extracted from the sealed transmission housing cavity and positioned externally, maintaining the seal while enabling easy access for maintenance
Solution Approach 2:
The transmission housing wall assembly serves as an intermediary structure, allowing external locking mechanisms to function while the cavity remains sealed for component protection
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 provides an energy-efficient transmission system that adapts to various operational demands, ensuring smooth transitions and effective braking, while maintaining the gearbox in a dry state to simplify maintenance, thus enhancing the performance and reliability of electrically propelled working machines.
Implementation Method 1
a first locking mechanism connected to one of the members of the first set of planetary members, the first locking mechanism being adapted to be controlled by a first fluid pressure conducted to the first locking mechanism
Implementation Method 2
a first planetary gear set comprising a first set of planetary members, the first set of planetary members comprising a first sun gear, a first ring gear and a first planet carrier carrying a first set of planet gears, the first set of planet gears being in meshing engagement with the first ring gear and the first sun gear
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
The present disclosure relates to a transmission arrangement. The transmission arrangement comprises a transmission housing comprising a transmission housing wall assembly defining a transmission housing cavity enclosing at least a first and a second planetary gear set, wherein at least an external portion of each one of a first and second locking mechanisms of the planetary gear sets is located on one side of the transmission housing wall assembly and the transmission housing cavity is located on an opposite side of the transmission housing wall assembly.