Split Vehicle Gearbox Reverse Driveability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current range gearboxes in vehicles face challenges in achieving a balance between minimizing diameter and weight to fit within vehicle design limits while maintaining driveability in reverse gear, as a larger planetary gear diameter increases weight and limits gear ratio, affecting reverse velocity and overall component efficiency.
Innovation Solution
A gearbox design incorporating a split gearbox and main gearbox with a combined largest gear ratio greater than the planetary gear ratio in reverse gear, allowing for acceptable reverse driveability without increasing the planetary gear ratio, and utilizing overlapping gear ratios in low and high range positions to minimize overall components and enhance torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the planetary gear diameter is increased to maintain driveability in reverse gear, then the reverse velocity and torque transmission are improved, but the weight and dimensions of the gearbox increase
Solution Approach 1:
The transmission system is divided into two separate gearboxes: a main gearbox containing reverse gear and a range gearbox containing the planetary gear. This segmentation allows the planetary gear to have smaller dimensions while the main gearbox provides the necessary reverse gear ratio, thus reducing the weight of the planetary gear assembly while maintaining reverse driveability through the combined system.
Solution Approach 2:
The solution moves from a single-gearbox design to a two-gearbox architecture, adding a dimensional aspect to the system configuration. By distributing functions across two separate units (main gearbox for reverse, range gearbox for planetary gearing), the system achieves the required performance without increasing the dimensions of individual components.
2Ease of operation
If the planetary gear ratio is increased to reduce reverse gear velocity, then the reverse driveability is improved, but the sun gear diameter must be reduced which decreases torque capacity
Solution Approach 1:
The torque transmission path is segmented between two gearboxes. The main gearbox handles the reverse gear function with adequate sun gear dimensions for torque capacity, while the range gearbox handles the planetary gear ratio function. This allows each component to be optimized for its specific function without compromise.
Solution Approach 2:
The main gearbox acts as an intermediary between the engine and the planetary gear in the range gearbox. It provides the reverse gear function and torque multiplication, allowing the planetary gear to operate with smaller dimensions while the overall system maintains the necessary torque capacity through the combined gear ratios.
3Adaptability or versatility
If a reverse gear is added to the main gearbox, then the reverse function is integrated, but the main gearbox length and vehicle weight increase
Solution Approach 1:
The reverse gear function is extracted from the main gearbox and placed in a separate range gearbox. This extraction prevents the main gearbox from being elongated by reverse gear components, maintaining its compact dimensions while the reverse function is still available through the two-gearbox system configuration.
4Ease of manufacture
If the planetary gear components are reduced in size to minimize gearbox dimensions, then the weight and manufacturing costs are reduced, but the torque transmission capacity decreases
Solution Approach 1:
The torque transmission function is segmented between two gearboxes. The main gearbox handles high-torque operations including reverse gear, while the range gearbox with planetary gear handles speed ratio operations. This allows the planetary gear components to be smaller and less expensive while the main gearbox provides the necessary torque capacity through its gear design.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a gearbox for vehicles, comprising a split gearbox (15C), a main gearbox (15A) and a range gearbox (15B), which is shiftable into a low range gear, a high range gear and a reverse gear; the range gearbox (15B) comprising a planetary gear (14) with a ring gear wheel (22), a sun gear wheel (18) and a planet carrier (20), on which at least one planet gear wheel (24) is rotatable mounted, which ring gear wheel (22) and sun gear wheel (18) engage with the at least one planet gear wheel (24); a gearbox housing (12) surrounding the planetary gear (14); a first axially movable coupling sleeve (42) arranged to engage the planet carrier (20) with the gearbox housing (12); and a second axially movable coupling sleeve (43) arranged to engage the ring gear wheel (22) with an output shaft (28) for achieving the reverse gear in the gearbox (2). The split gearbox (15C) and the main gearbox (15A) are together arranged to have a combined largest gear ratio which is larger than the gear ratio in the planetary gear (14) in the range gearbox (15B) when the planetary gear (14) is shifted into the reverse gear.