Variator Gearbox Speed Control for Harvesters
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Solution Overview
Problem
Self-propelled forage harvesters face challenges in adjusting the speed of harvesting headers efficiently and conveniently, especially under load, with existing solutions requiring high assembly effort, fixed gear ratios, or low efficiency hydraulic adjustments.
Innovation Solution
A drive connection system featuring a variator gearbox between the input and output shafts, allowing for continuous speed adjustment and soft start-up capabilities, utilizing a clutch to couple and uncouple the drive connection and incorporating a brake for quick stop functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If replaceable pulleys are used in the belt drive to achieve variable speeds, then different gear ratios and drive speeds are achieved, but the assembly effort required to replace the discs is high and cannot be carried out during ongoing harvesting operations
Solution Approach 1:
The patent applies a continuously variable ratio transmission (CVR) mechanism that allows dynamic adjustment of the gear ratio during operation. The transmission unit comprises a drive wheel with a variable effective diameter and a driven wheel with a variable effective diameter, where the ratio of these diameters can be continuously changed without discrete replacements, enabling variable speed adjustment without high assembly effort
Solution Approach 2:
The patent replaces the mechanical pulley replacement system with a hydraulic control system. Hydraulics are used to adjust the effective diameters of the drive and driven wheels, allowing continuous speed variation without mechanical disassembly or reconfiguration of the transmission components
2Device complexity
If fixed gear ratios are used with pulleys, then simple structure is maintained, but the ability to adjust speed continuously during operation is lost
Solution Approach 1:
The transmission unit is designed as a dynamic system where the effective diameters of the drive and driven wheels can be continuously adjusted during operation. This allows the gear ratio to vary smoothly rather than being fixed in discrete steps, providing continuous speed adjustment capability while maintaining a relatively simple mechanical structure
Solution Approach 2:
The patent employs hydraulic actuators to adjust the effective diameters of the drive and driven wheels. The hydraulic system enables continuous variation of the gear ratio by controlling the position of the adjustable diameter elements, providing smooth speed adjustment without complex mechanical linkages
3Adaptability or versatility
If hydraulic drive is used to achieve variable speed adjustment, then continuous speed control is possible, but the efficiency is low
Solution Approach 1:
The patent uses a hybrid approach where hydraulics are employed only for the variable ratio transmission function, while the main power transmission remains mechanical. The hydraulic system adjusts the effective diameters of the drive and driven wheels to achieve variable speed control, but the overall drive train maintains mechanical efficiency through direct mechanical coupling of the CVR unit to the harvest header
4Adaptability or versatility
If a power-split transmission unit with hydraulic auxiliary drive is used, then variable output speed is enabled and previously mentioned disadvantages are eliminated, but the design effort and system complexity increase considerably
Solution Approach 1:
The patent extracts the variable ratio transmission function into a separate, self-contained transmission unit that can be independently adjusted. This transmission unit with its drive and driven wheels having variable effective diameters is coupled to the harvest header, allowing variable speed control without requiring a complete power-split transmission system, thereby reducing overall design complexity
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
Enables efficient, continuous speed adjustment of the harvesting header during operation, gentle start-up, and quick stopping, while maintaining a compact and weight-optimized design with reduced frictional losses.
Implementation Method 1
a variator gear (5) acting between the input shaft (10) and the output shaft (20)... The set ratio of the effective diameter of the drive wheel (11) and driven wheel (21) determines the speed ratio
Implementation Method 2
a clutch (12) which establishes or releases a drive connection between the input shaft (10) and the output shaft (20)
Implementation Method 3
an output shaft brake (22) which can be operated to bring the output shaft (20) to a standstill
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The machine (1) has a gear arrangement (3) comprising an input shaft (10) and an output shaft (20) drivable by a drive motor. The input and output shafts are in drive connection with a harvest attachment unit e.g. maize denture, to drive the harvest attachment unit, which is attached to the harvesting machine. The input shaft is engaged and disengaged with/from the output shaft. The drive connection has a variator gearbox (5) acting between the input and output shafts. The variator gearbox comprises a drive wheel (11) with variable effective diameter.