Compact Transmission Arrangement With Nested Differential
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Solution Overview
Problem
Current transmission arrangements for motor vehicles are not sufficiently space-efficient and compact, particularly in small vehicles with limited engine compartment space, limiting their versatility and increasing installation costs.
Innovation Solution
A transmission arrangement featuring a coaxial drive shaft with two interconnected planetary gear sets and a differential, where the differential is partially housed within the cylindrical volume of the sun gear of the second planetary gear set, reducing overall axial length and allowing for a more compact design, and utilizing a two-element bevel gear differential and a fixed-floating bearing arrangement to minimize installation space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional transmission arrangements are used, then torque transfer and speed modification functions are achieved, but installation space requirements are excessive for compact vehicles
Solution Approach 1:
The differential is positioned inside the cylindrical volume of the sun gear of the second planetary gear set, creating a nested configuration where one component occupies the internal space of another. This nesting arrangement significantly reduces the overall installation space while maintaining both torque transfer and speed modification functions across various vehicle types.
Solution Approach 2:
The transmission arrangement transitions from a conventional multi-dimensional layout to a predominantly axial arrangement, with components stacked along the axial direction. The differential is positioned axially within the sun gear volume, and the planetary gear sets are arranged axially, creating a compact design that fits the limited space in modern vehicles while preserving functional versatility.
2Length of stationary object
If the differential is positioned outside the planetary gear sets, then ease of manufacturing is improved, but axial length and installation space increase
Solution Approach 1:
The differential is nested within the sun gear of the second planetary gear set, utilizing the internal cylindrical volume of the sun gear to house the differential components. This nesting eliminates the need for additional axial space while the modular design of the nested components maintains manufacturing feasibility through standardized sub-assemblies.
Solution Approach 2:
The transmission arrangement is divided into modular segments: the first planetary gear set, the second planetary gear set with integrated differential, and the connecting shafts. This segmentation allows each module to be manufactured and assembled separately, reducing overall assembly complexity despite the compact nested configuration.
3Area of stationary object
If a hollow drive shaft is used to enclose additional shafts, then radial space is reduced, but manufacturing complexity increases
Solution Approach 1:
The drive shaft is designed as a hollow structure that encloses additional shafts within its internal volume. This nested configuration allows multiple shafts to occupy the same radial space, significantly reducing the overall radial footprint of the transmission arrangement while the modular shaft design maintains manufacturing feasibility.
Solution Approach 2:
The hollow drive shaft serves multiple functions: it acts as a structural support element, provides a protective enclosure for internal shafts, and serves as a torque transmission path. This multi-functionality reduces the need for separate components, thereby reducing device complexity despite the advanced structural requirements.
Data Source
AI summary
A transmission (GA) for an axle drive (1) of a motor vehicle includes a drive shaft (AN), two output shafts (AB1, AB2), at least four shafts (W1, W2, W3, W4), a differential, and two interconnected planetary gear sets (PS1, PS2). The drive shaft (AN) is a hollow shaft, and the drive shaft (AN) is coaxial with at least one of the two output shafts (AB1, AB2). The differential (D) is arranged, at least partly, within a cylindrical volume. An outer shell surface of the cylindrical volume is defined by an inner shell surface of a sun gear (SO2) of the second planetary gear set (PS2). A diameter of inner shell surface corresponds to an inner diameter of the sun gear (SO2) of the second planetary gear set (PS2).