Range Gearbox Helical Sun Wheel Axial Force Absorption
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Solution Overview
Problem
In heavy vehicle transmission systems, the use of helical teeth in range gearboxes generates axial forces that are difficult to absorb due to limited space in the basic gearbox, leading to excessive loading on mainshaft and input bearings.
Innovation Solution
A range gearbox configuration with a planetary gear and a sun wheel having helical external teeth, where the axial forces are directed towards the basic gearbox, and an outer bearing is used to absorb these forces, allowing the mainshaft and input bearings to operate under reduced stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If helical teeth are used in the planetary gear to reduce noise and optimize power transfer, then noise level is reduced and power transfer is optimized, but axial forces are generated that push the mainshaft and ring gear in opposite directions
Solution Approach 1:
The invention extracts the force absorption function from the basic gearbox bearings and relocates it to a dedicated thrust bearing arrangement in the range gearbox. The thrust bearing is specifically positioned to absorb axial forces generated by the helical planetary gears, separating the power transfer function from the force absorption function.
Solution Approach 2:
The thrust bearing acts as an intermediary element between the planetary gear set and the mainshaft bearing system. It mediates the axial forces generated by helical teeth engagement, preventing these forces from being transmitted to the mainshaft and basic gearbox bearings.
2Force
If force-absorbing bearings are enlarged to absorb axial forces from helical gears, then force absorption capacity is improved, but the space in the basic gearbox is exceeded
Solution Approach 1:
The invention segments the force absorption function into two separate locations: the thrust bearing in the range gearbox handles axial forces from helical gears, while the basic gearbox bearings focus on radial loads and other forces. This segmentation allows compact bearing dimensions in the space-constrained basic gearbox.
Solution Approach 2:
The invention relocates the primary axial force absorption mechanism from the radial plane (basic gearbox bearings) to the axial dimension (thrust bearing in range gearbox). This dimensional shift allows force absorption without increasing the radial footprint within the basic gearbox housing.
3Force
If multiple bearings are configured to absorb forces in opposite directions, then force absorption in all directions is achieved, but the complexity of bearing configuration increases
Solution Approach 1:
The invention merges the axial force absorption function into a single thrust bearing location in the range gearbox, combining what would otherwise require multiple complex bearing arrangements in the basic gearbox. This single thrust bearing handles all axial forces from the planetary gears, simplifying the overall bearing configuration.
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 optimizes force absorption, extends the service life of bearings by minimizing axial forces on them, and allows for a more efficient power transfer while maintaining a compact design.
Implementation Method 1
an outer bearing which is situated at the housing aperture between the mainshaft and the housing and which fixes the mainshaft to the housing while at the same time allowing it to rotate relative to the housing
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
A basic gearbox (10) for a motor vehicle comprising a surrounding housing (11) in which there is a mainshaft (2) which has its first end connected via a mainshaft forward bearing (6) to an input shaft (1), and its second end running through an aperture (12) in the surrounding housing (11), with a countershaft (4) arranged to transmit rotation from the input shaft (1) to the mainshaft (2) via various selectable gear ratios, and a mainshaft rear bearing (7) situated between the mainshaft (2) and the housing aperture (12), with axial support against the housing (11) of the basic gearbox (10), in order to absorb axial forces in the mainshaft (2) towards the second end of the mainshaft. An outer bearing (8) is provided between the mainshaft (2) and the housing aperture (12), with axial support against the housing (11) of the basic gearbox (10), in order to absorb axial forces in the mainshaft (2) which act towards the first end of the mainshaft. According to a second aspect of the invention, a range gearbox (20) is situated on the mainshaft (2) outside the basic gearbox (10) and has a sun wheel (21) with helical teeth which during forward movement of the vehicle in low-range operation give rise to axial forces in the mainshaft (2) which act towards the first end of the mainshaft and are absorbed by the outer bearing (8).