Planetary Gear Transmission With External Locking Mechanisms
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Solution Overview
Problem
The existing gearbox technologies for electrically propelled working machines, such as haulers and excavators, face challenges in adapting to the different speed range requirements compared to conventional internal combustion engine vehicles, necessitating an improved transmission arrangement for efficient operation in rough terrain.
Innovation Solution
A transmission arrangement featuring a two-stage setup 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 speed and braking torque, facilitating energy efficiency and maintenance accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If locking mechanisms are placed inside the transmission housing cavity, then the gearbox provides compact integration, but maintenance and repair become difficult due to inaccessibility of internal components
Solution Approach 1:
The transmission arrangement is divided into distinct segments: the transmission housing wall assembly separates the housing cavity (containing planetary gear sets) from the external region (containing locking mechanisms). This segmentation allows each component to be optimized independently - internal components for compact integration and external locking mechanisms for easy maintenance access.
Solution Approach 2:
The locking mechanisms are extracted from the internal housing cavity and positioned externally on the transmission housing wall assembly. This extraction resolves the contradiction by placing maintenance-critical components outside the sealed housing while maintaining functional integration through the wall assembly connection.
2Reliability
If fluid pressure is continuously applied to locking mechanisms, then the gearbox maintains reliable gear engagement, but energy consumption increases due to continuous hydraulic system operation
Solution Approach 1:
The hydraulic system operates periodically rather than continuously - fluid pressure is applied only when gear shifts or locking actions are required. The locking mechanisms maintain their position through mechanical locking without continuous hydraulic pressure, enabling the system to return to a low-energy standby state between operational demands.
Solution Approach 2:
The locking mechanisms utilize spring elements that automatically return to their default state after hydraulic pressure is released. This self-service capability allows the system to maintain reliability through passive mechanical retention while minimizing active energy consumption during idle periods.
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
This solution enables smooth transitions between locked and released conditions, providing efficient energy use, effective braking, and simplified maintenance by keeping external locking mechanisms outside the transmission housing, enhancing the gearbox's performance for electric machines in demanding environments.
Implementation Method 1
the first locking mechanism being adapted to be controlled by a first fluid pressure conducted to the first locking mechanism such that for at least a first fluid pressure equal to zero overpressure, the first locking mechanism is adapted to assume a locked condition
Implementation Method 2
the first set of planet gears being in meshing engagement with the first ring gear and the first sun gear
Data Source
AI summary
A transmission arrangement includes a transmission housing including 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.