Work Vehicle Transmission Layout With Two-Stage Gear Reduction
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Solution Overview
Problem
Conventional work vehicles have a power transmission unit that is not compact due to single-stage speed reduction between the transmission shaft and differential device, leading to enlarged driven gears and a larger power transmission unit.
Innovation Solution
A power transmission unit with a first and second gear mechanism for two-stage speed reduction, allowing for compactization of the driven gears and the unit itself, along with a support shaft and input shaft arrangement to optimize space usage, and a switchover device for switching between two-wheel and four-wheel drive states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-stage speed reduction is used in the power transmission unit, then the structure is simpler, but the driven gear becomes enlarged and the power transmission unit becomes larger
Solution Approach 1:
The power transmission unit is segmented into a first gear mechanism and a second gear mechanism, each performing partial speed reduction. This division allows each gear to be smaller in size while achieving the same total speed reduction ratio, resolving the contradiction between structural simplicity and compact size.
2Device complexity
If single-stage speed reduction is used, then fewer gear mechanisms are needed, but the driven gear size increases
Solution Approach 1:
The single-stage speed reduction is segmented into two stages, with each stage using a smaller gear pair. The first gear mechanism performs initial speed reduction, and the second gear mechanism performs further reduction, allowing both driven gears to be compact in size.
Solution Approach 2:
The patent utilizes 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 drive gear axis, while the second driven gear rotates about a parallel axis, effectively using three-dimensional space to accommodate multiple gear mechanisms without increasing overall footprint.
Data Source
AI summary
A work vehicle includes a power transmission unit having a differential device for transmitting power to left and right axles and a power transmission mechanism for transmitting power to the differential device, and a transmission shaft for transmitting power to the power transmission unit. The power transmission mechanism includes a first gear mechanism to which power from the transmission shaft is transmitted and a second gear mechanism for transmitting power from the first gear mechanism to the differential device.