Transmission Device Secondary Power Splitting Weight Reduction
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Solution Overview
Problem
Existing transmission devices for agricultural or municipal vehicles with step-up gear units are heavy and costly due to the large dimensions required to handle high power, particularly in the auxiliary drive output shaft, which affects their weight and production costs.
Innovation Solution
A transmission device with secondary power splitting, featuring a hydrostatic and mechanical branch summed by a summing gear system, where the central transmission shaft is directly coupled to the drive engine and hydraulic pumps, allowing for continuous variation of transmission ratios and reducing the size and weight of the auxiliary drive output shaft, enabling smaller and lighter design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the auxiliary drive output shaft is designed to handle high power with large dimensions, then the power transmission capability is improved, but the weight and production costs increase undesirably
Solution Approach 1:
The power flow is segmented into multiple paths: a mechanical branch and a hydrostatic branch. The mechanical branch handles auxiliary drive functions while the hydrostatic branch handles propulsion, allowing each shaft to be optimized for its specific function rather than being oversized for all functions
Solution Approach 2:
The hydrostatic branch replaces part of the mechanical power transmission system with a hydrostatic variator, allowing continuous transmission ratio variation and reducing the mechanical power that must be handled by the auxiliary drive output shaft
2Power
If the auxiliary drive output shaft is made with large dimensions to handle high power, then the power transmission capability is improved, but the production costs increase undesirably
Solution Approach 1:
The power flow is segmented into multiple paths: a mechanical branch and a hydrostatic branch. The mechanical branch handles auxiliary drive functions while the hydrostatic branch handles propulsion, allowing each shaft to be optimized for its specific function rather than being oversized for all functions
Solution Approach 2:
The hydrostatic branch replaces part of the mechanical power transmission system with a hydrostatic variator, allowing continuous transmission ratio variation and reducing the mechanical power that must be handled by the auxiliary drive output shaft
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 results in a more affordable, lighter transmission device that maintains high power density and efficiency, with the possibility of boost operation during PTO, utilizing a centrally arranged gearwheel for connecting driving gearwheels to hydraulic pumps and the auxiliary drive output shaft, and employing a constant oblique-axis hydrostatic unit for reduced power losses.
Implementation Method 1
the transmission ratios of the transmission device can in each case be continuously varied within the transmission ratio ranges by means of a hydrostatic variator in the area of the hydrostatic branch
Implementation Method 2
the hydrostatic and mechanical branches can be summed by a summing gear system provided in the area of a central transmission shaft
Data Source
AI summary
A transmission device with secondarily coupled power splitting, having hydrostatic and mechanical branches which can be summed by a summing gear system provided in the area of a central transmission shaft. At least two transmission ratio ranges, in the forward and reverse driving directions, can be obtained such that within the transmission ratio ranges the transmission ratio can, in each case, be varied continuously by a hydrostatic variator in the area of the hydrostatic branch. On the transmission input side, the central transmission shaft can directly couple a drive engine and functionally connect to both an auxiliary drive output shaft and a hydrostatic shaft of the variator, in the form of countershafts, and also to hydraulic pumps in the area of the transmission input. In the area of the transmission output, the central transmission shaft is coupled to a further hydrostatic shaft in the form of a countershaft.