Power Shift Transmission Nested Shaft Layout
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Solution Overview
Problem
Current power shift transmissions for agricultural machines are complex in production and lack the ability to implement a wide range of gear variants while maintaining a compact size, limiting their usability across various applications.
Innovation Solution
The power shift transmission incorporates an input shaft unit with an inner and outer shaft arranged coaxially, connected via a layshaft, which includes a planetary transmission stage with a sun gear, ring gear, and planet gears, allowing for multiple shifting states and a compact design by enabling independent operation of the sun gear and planetary group, and using multi-plate clutches for gear coupling and uncoupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a two-stage power shift transmission is configured with planetary transmissions and clutches in a modular system, then the transmission can operate in fixed drive mode, gear reduction mode, and reversing mode, but the transmission becomes complex in terms of production technology and cannot implement additional operating modes such as crawling gear mode
Solution Approach 1:
The transmission is divided into two independent shift groups (upstream group and downstream group), each capable of providing multiple gear ratios. This segmentation allows each group to be optimized for specific functions while collectively providing a wide range of operating modes including crawling gear mode, without requiring a completely different transmission architecture for each mode.
Solution Approach 2:
The layshaft is designed to serve multiple functions: it connects the inner shaft to the outer shaft, provides gear ratio changes through gearwheel pairs, and enables crawling gear mode when both shift groups are engaged. This multi-functionality reduces the need for separate mechanisms for each operating mode, simplifying the overall transmission design while maintaining versatility.
2Adaptability or versatility
If a high number of gear variants is implemented, then the transmission becomes larger and less compact, but a compact size is required for agricultural machines
Solution Approach 1:
The inner shaft is arranged coaxially within the outer shaft, creating a nested configuration. The layshaft connects these concentric shafts and provides gearwheel pairs that can be engaged or disengaged to provide different gear ratios. This nested arrangement allows multiple gear variants to be implemented within a compact radial space, avoiding the need for a larger transmission housing.
3Adaptability or versatility
If the inner shaft and outer shaft are connected via a layshaft with gearwheel pairs, then multiple gear ratios can be achieved, but the transmission requires more components and increased complexity
Solution Approach 1:
The layshaft serves as a common intermediate shaft for both the upstream shift group (connecting inner shaft to auxiliary shaft) and the downstream shift group (connecting auxiliary shaft to outer shaft). By merging these functions into a single layshaft with appropriately positioned gearwheel pairs, the design reduces the total number of separate shafts and gear mechanisms needed to achieve multiple gear ratios.
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 configuration allows for a high number of gear variants with a compact size, enabling the transmission of torque across different load states and rotational speeds, enhancing the versatility and efficiency of the power shift transmission.
Implementation Method 1
the layshaft has at least one planetary transmission stage with at least one sun gear, a ring gear, and a planetary group consisting of at least one first planet gear and at least one second planet gear
Implementation Method 2
using multi-plate clutches for gear coupling and uncoupling
Data Source
AI summary
A power shift transmission for an agricultural machine includes a transmission housing, an input shaft unit and an output shaft. The input shaft unit and the output shaft extend at least partially inside the housing. The transmission includes an auxiliary shaft arranged offset but parallel between the input shaft unit and the output shaft inside the housing. The input shaft unit and the auxiliary shaft are connected together via an upstream group, and the auxiliary shaft and the output shaft are connected together via a downstream group. Each of the upstream and downstream shift groups includes gearwheel pairs which may be individually selectively coupled. The input shaft unit includes an outer shaft and an inner shaft which is arranged coaxially in the outer shaft and which is rotatable relative to the outer shaft. The inner shaft and the outer shaft are connected together via a layshaft.