Inline Dual Planetary Variator for Work Vehicle Drivetrain
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Solution Overview
Problem
Conventional dual output work vehicle drivetrains rely on large hydrostatic drives, which are inefficient, costly, and add weight and bulk, and provide only stepped speed selection, limiting efficiency and flexibility in ground speed control.
Innovation Solution
A dual output work vehicle drivetrain incorporating a variator assembly with a variator motor and gearbox, including a planetary gear system, that allows independent speed control of shaft-powered implements and ground wheels, enabling non-stepped or infinitely variable power output over a wide range of ground speeds by summing power outputs from the variator motor and prime mover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If large hydrostatic drives are used in conventional dual output work vehicle drivetrains, then ground speed control is achieved, but drivetrain efficiency decreases and weight and cost increase
Solution Approach 1:
The drivetrain is segmented into two independent power paths: a primary power path from the prime mover through a transmission to the ground wheels, and a secondary power path from the prime mover through a variator assembly to the auxiliary PTO shaft. This segmentation allows each path to be optimized independently, with the variator assembly providing flexible ground speed control without requiring a large hydrostatic drive, thereby improving overall drivetrain efficiency while maintaining adaptability.
2Power
If large hydrostatic drives are used, then power output control is achieved, but device size and cost increase
Solution Approach 1:
The variator assembly merges the primary power path from the prime mover with a secondary power path through the planetary gear system. The planetary gear system combines torques from both power paths at the variator input shaft, allowing compact power output control without requiring a large hydrostatic drive. This merging enables effective power control while reducing the size and complexity of the variator assembly.
3Adaptability or versatility
If stepped speed selection is used in conventional drivetrains, then ground speed control is achieved, but flexibility and efficiency are limited
Solution Approach 1:
The variator assembly replaces stepped speed selection with continuous variable speed control through the planetary gear system. The system dynamically adjusts the gear ratio by varying the contribution of the secondary power path through the variator motor, enabling smooth, non-stepped ground speed selection. This dynamic control provides superior flexibility and operational efficiency compared to conventional stepped transmissions.
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 reduces the size and power requirements of the variator motor, improves overall drivetrain efficiency, and allows for constant engine speed operation, providing efficient and flexible ground speed control while minimizing weight and cost.
Implementation Method 1
The planetary gear system is coupled to the variator motor and to the auxiliary PTO shaft. The planetary gear system is rotatable about a planetary axis, which is coaxial or inline with the primary power path axis.
Data Source
AI summary
A high efficiency work vehicle drivetrain contains a variator having an inline dual planetary configuration. The work vehicle drivetrain includes an engine, an auxiliary power takeoff (PTO) shaft coupled to the engine and rotatable about a primary power path axis when driven by the engine, and the variator assembly. The variator assembly includes a variator motor and a variator gearbox. The variator gearbox contains a planetary gear system, which is coupled to the variator motor and to the auxiliary PTO shaft. The planetary gear system is rotatable about a planetary axis, which is coaxial with the primary power path axis.