Gearbox Assembly Coupling Ratio Stage for Seamless Power Shifting
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Solution Overview
Problem
Agricultural working vehicles require transmission arrangements that cover a wide range of driving speeds with a large spread between slowest and fastest transmission stages, necessitating a high number of gears, but existing designs often require an interruption in traction when shifting between gear groups, which is undesirable for driving comfort and operational efficiency.
Innovation Solution
A transmission arrangement featuring a parallel shift transmission with countershafts and a coupling ratio stage that allows power shifting between gear groups by bypassing switching groups, enabling preselection of the next gear group and load shift without traction interruption, using a bridge gear or equivalent ratio stage, preferably designed as a spur gear stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional group shift transmission is used to cover a wide range of driving speeds, then the transmission can provide the required speed range, but traction interruption occurs when shifting between gear groups
Solution Approach 1:
An intermediary transmission stage is introduced between the parallel shift transmission and the group shift transmission. This intermediary stage acts as a bridge that allows seamless transition between gear groups by providing an intermediate gear ratio that connects the two transmission stages, thereby maintaining continuous power flow and eliminating traction interruption during group shifting operations
Solution Approach 2:
The transmission system is segmented into three distinct stages: parallel shift transmission, intermediary transmission stage, and group shift transmission. This segmentation allows each stage to perform its specific function independently - the parallel shift transmission handles fine gear changes, the intermediary stage bridges gear groups, and the group shift transmission provides coarse range changes - thereby enabling smooth transitions without power interruption
2Speed
If the number of gears is increased to cover a wide speed range with small geometric increments, then the transmission can provide precise speed control, but the device complexity increases
Solution Approach 1:
The transmission system divides the total gear set into two segments: a parallel shift transmission with a smaller number of gears for fine speed adjustments within a gear group, and a group shift transmission with multiple gear groups for coarse range changes. This segmentation reduces the complexity of any single shifting mechanism while maintaining the ability to cover a wide speed range with precise control
Solution Approach 2:
Different parts of the transmission system are optimized for different functions: the parallel shift transmission is designed for quick, frequent gear changes within a narrow ratio range, while the group shift transmission is designed for less frequent but larger ratio changes between groups. This local optimization allows each subsystem to be simpler while the combination provides comprehensive speed control
Data Source
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AI summary
Transmission arrangement (30), in particular for an agricultural work vehicle (10), comprising a parallel transmission (50) with several gear stages (68-1, 68-2, 68-3, 68-4, 70-1, 70-2, 70-3, 70-4) and an input shaft (52) from which a drive power can be distributed via a first and a second shift element (541, 542) to respective countershafts (56-1, 56-2), and an output shaft (58) wherein the drive power can be transmitted from each of the countershafts (56-1, 56-2) to the output shaft (58) as required, a range transmission (80) with several shift groups (821, 822,...) and an output shaft (92) wherein the shift groups (82-1, 82-2,...) are connected to the output shaft (58-1) of the Parallel shift gearbox (50) are drive-connectable to direct the drive power to the output shaft (92) of the group shift gearbox (80) and a coupling reduction stage (84) with which the drive power is transferred by bypassing the shift groups (82-1, 82-2,...) of the group shift transmission (80) is conductive from one of the countershafts (56-1, 56-2) to the output shaft (92) of the group shift transmission (80). Fig. 3.