Utility Vehicle Transmission Segmentation for Compact Four-Wheel Drive
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Solution Overview
Problem
Conventional utility vehicles that switch between two-wheel and four-wheel drive modes face a size increase in the transmission due to the need for larger gear diameters in the output shaft and rear axle to maintain a predetermined inter-shaft distance, leading to increased transmission size.
Innovation Solution
The implementation of a rear wheel drive output shaft between the front wheel drive output shaft and the rear axle allows for a reduction in gear diameters, preventing size increase while maintaining the required inter-shaft distance, along with a two-wheel-four-wheel drive switching device for easy mode switching and a differential lock to prevent rear wheel idling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a predetermined inter-shaft distance is provided between the output shaft and rear axle to obtain predetermined reduction ratio or strength, then the gear diameters must be increased, but the transmission size increases
Solution Approach 1:
The transmission system is segmented into two separate output shafts: a front wheel drive output shaft and a rear wheel drive output shaft. This segmentation allows each shaft to have optimized gear diameters suitable for its specific function, rather than requiring one oversized gear system to handle all requirements. The rear wheel drive output shaft specifically uses smaller diameter gears compared to conventional single-output-shaft designs.
Solution Approach 2:
The rear wheel drive output shaft acts as an intermediary component between the input shaft and the rear axle. By introducing this intermediate shaft with appropriately sized gears, the system achieves the necessary torque transmission and reduction ratio without requiring excessively large gear diameters in the final drive stage, thus maintaining compact transmission dimensions while ensuring sufficient strength.
2Power
If a predetermined inter-shaft distance is provided between the output shaft and rear axle to obtain predetermined reduction ratio, then the gear diameters must be increased, but the transmission size increases
Solution Approach 1:
The power transmission path is divided into separate routes for front and rear wheel drive. The rear wheel drive output shaft provides a dedicated transmission path with optimized gear ratios, allowing the system to achieve the required reduction ratio through multiple smaller gear stages rather than one or two large diameter gears, thereby reducing overall transmission size.
Solution Approach 2:
The patent arranges the transmission components in a three-dimensional configuration that optimizes space utilization. By positioning the rear wheel drive output shaft and its gear group in a specific spatial arrangement relative to the input shaft and rear axle, the system achieves the necessary reduction ratio while minimizing the transmission's envelope dimensions through clever spatial planning rather than simply increasing gear diameters.
Data Source
AI summary
A utility vehicle 1 prevents a size increase of a transmission while ensuring a predetermined inter-shaft distance between an output shaft and a rear axle. The utility vehicle 1 is capable of switching a two wheel drive mode for transmitting drive force to rear wheels 3 and a four wheel drive mode for transmitting the drive force to front wheels 2 and the rear wheels 3, a transmission 9 includes an input shaft 92 to which the drive force from an engine 8 is inputted, a front wheel drive output shaft 94 for transmitting the drive force of the input shaft 92 to the front wheels 2, and a rear axle 96 for transmitting the drive force of the input shaft 92 to the rear wheels 3. A rear wheel drive output shaft 95 is provided in a motive power transmission route between the front wheel drive output shaft 94 and the rear axle 96.