Two-Stage Gear Reduction Layout for Compact Work Vehicle Drivetrains
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Solution Overview
Problem
Conventional work vehicles have power transmission units that are not compact due to single-stage speed reduction, leading to enlarged driven gears and increased unit size.
Innovation Solution
A power transmission unit with a first and second gear mechanism, allowing two-stage speed reduction between the transmission shaft and differential device, featuring first and second drive and driven gears with orthogonal and parallel rotational axes, respectively, and a support shaft to minimize height and enable space optimization for other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-stage speed reduction is used between transmission shaft and differential device, then power transmission is simpler, but driven gear size must be enlarged leading to increased unit size
Solution Approach 1:
The power transmission mechanism is segmented into two separate gear mechanisms: a first gear mechanism with a first drive gear and first driven gear, and a second gear mechanism with a second drive gear and second driven gear. This segmentation allows the speed reduction function to be distributed across multiple smaller gear pairs rather than requiring one large single-stage reduction, thereby reducing the overall size of the power transmission unit while maintaining the required speed reduction ratio.
2Device complexity
If single-stage speed reduction is used, then fewer gear components are needed, but the driven gear becomes too large for compact design
Solution Approach 1:
The single large driven gear is segmented into two smaller driven gears: a first driven gear in the first gear mechanism and a second driven gear in the second gear mechanism. Each gear operates within a manageable size range, allowing for compact overall design while achieving the cumulative speed reduction effect of both stages.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement by positioning the first and second gear mechanisms at different locations and orientations. The first driven gear rotates about an axis orthogonal to the first drive gear, while the second driven gear rotates about an axis parallel to the second drive gear, effectively using spatial dimensionality to pack multiple gear mechanisms into a compact volume without excessive gear sizes.
3Volume of moving object
If two-stage speed reduction is implemented, then compactization of driven gears is achieved, but power transmission path becomes longer
Solution Approach 1:
The first driven gear and second drive gear are merged by making them rotatable about the same rotational axis, allowing them to be positioned adjacent to each other. This merging of functional elements minimizes the transmission path length between gear mechanisms while maintaining the two-stage speed reduction configuration, thereby achieving compact design without excessive path length.
Data Source
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AI summary
A work vehicle includes a power transmission unit (22) having a differential device (24) for transmitting power to left and right axles (21) and a power transmission mechanism (25) for transmitting power to the differential device (24), and a transmission shaft (23) for transmitting power to the power transmission unit (22). The power transmission mechanism (25) includes a first gear mechanism (28) to which power from the transmission shaft (23) is transmitted and a second gear mechanism (29) for transmitting power from the first gear mechanism (28) to the differential device (24).