Power Split Transmission for Tractor Torque Reversal
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Solution Overview
Problem
Modern agricultural tractors require a simple and efficient power shuttle transmission module that can reverse the direction of torque transfer between an input shaft and an output shaft, while minimizing complexity and cost, and maintaining a constant drive direction for secondary power branches.
Innovation Solution
A power-split transmission system comprising a forward-reverse transmission module with first and second clutches, an epicyclic module, and a secondary power branch, where the first clutch provides a direct connection for forward gear and the second clutch uses a combination of gear sets with odd and even numbers of gears to reverse torque, and the epicyclic module maintains a constant drive direction for the secondary power branch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an epicyclic-based shuttle module is used to reverse torque direction, then reverse gear functionality is achieved, but torque transfer efficiency is reduced and construction complexity increases
Solution Approach 1:
The transmission system is divided into separate functional modules: a forward-reverse transmission module using simple gear sets for direction reversal, and an epicyclic module dedicated solely to power splitting. This segmentation allows each module to perform its specific function efficiently without the complexity of integrating both functions in a single epicyclic-based shuttle module.
Solution Approach 2:
Instead of using a complex epicyclic arrangement to achieve both power splitting and reverse gear functions (as in prior art), the invention inverts the approach by using simple gear sets for reversal and a dedicated epicyclic module for power splitting. This inversion of functional assignment simplifies the overall system architecture.
2Ease of operation
If a dedicated reverse gear element is included in the main gearbox, then reverse functionality is achieved, but device complexity and cost increase
Solution Approach 1:
The forward-reverse transmission module using simple gear sets serves multiple purposes: it provides reverse gear functionality while also serving as part of the overall transmission system. This multi-functional design eliminates the need for separate dedicated reverse gear elements, reducing overall gearbox complexity.
3Ease of operation
If the power shuttle module is located downstream of the power split transmission, then reverse functionality is achieved, but the drive direction to the secondary power branch varies
Solution Approach 1:
The forward-reverse transmission module performs the direction reversal action before the power reaches the epicyclic module and secondary power branch. This preliminary reversal ensures that the drive direction to the secondary power branch remains constant regardless of whether the vehicle is moving forward or backward, simplifying bearing support requirements.
Data Source
AI summary
A power-split transmission for a vehicle comprises a forward-reverse transmission module, an epicyclic module and a secondary power branch. The forward-reverse power shuttle module (12) comprises an input shaft (22) coupled to a primary motor (20) and an output shaft (38). Also included, first and second clutches (30,48) are alternatively engageable to close respective forward and reverse drive paths between the input shaft and output shaft. Engagement of the first clutch couples the input shaft directly to the output shaft. Engagement of the second clutch couples the input shaft to the output shaft via first and second gear sets (32, 34, 36, 42, 44) which each comprise a plurality of meshed gears. One of the gear sets (32, 34, 36) comprises an odd number of gears and the other gear set (42, 44) comprises an even number of gears. The epicyclic module comprises a first epicyclic input connected to the output shaft of the forward-reverse transmission module, a second epicyclic input connected to an output side of the secondary power branch, and an epicyclic output. The secondary power branch derives power from the primary motor via the first gear set.