Planetary Differential Transmission for Preassembled Drivetrains

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Solution Overview

Problem

Existing vehicle transmissions require the drive unit to be connected to the transmission for storage and transport, which complicates assembly and increases the risk of components becoming detached.

Innovation Solution

A compact transmission design with a differential having a first and second planetary gear set, where the planet carrier of the second gear set is rotationally fixed and axially secured to the housing, allowing for preassembly and transportation without needing a drive unit or other components connected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the drive unit is connected to the transmission for storage and transport, then components of the transmission are prevented from becoming detached, but the assembly process becomes more complex and requires additional installation space

Engineering Contradiction:

Improveprevention of component detachmentVSAvoidassembly process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The transmission is divided into modular components that can be independently assembled and secured. The planet carrier is designed as a separate module that can be mounted to the housing with integrated securing features, allowing the transmission to be preassembled without requiring the complete drive unit connection for component stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The planet carrier is pre-secured to the housing using integrated mounting features and retaining elements before the transmission is shipped or stored. This preliminary securing action prevents component detachment during transport, eliminating the need to keep the drive unit connected for protection purposes.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the planet carrier is mounted to the housing with integrated lubricant supply, then preassembly without drive unit is enabled, but additional radial or axial installation space is required

Engineering Contradiction:

Improvepreassembly capabilityVSAvoidinstallation space

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

The lubricant supply system is merged with the planet carrier mounting structure. The lubricant feed passages are integrated directly into the housing features that also serve to mount and secure the planet carrier, combining multiple functions into a single integrated structure that eliminates the need for separate lubricant supply components requiring additional space.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The housing features serving as mounting points for the planet carrier are designed to simultaneously provide lubricant supply functions. These universal features perform multiple roles: mechanical support, positional securing, and lubricant delivery, thereby enabling preassembly without requiring dedicated space for separate lubricant supply infrastructure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If pressing-in processes are used to secure the planet carrier, then a secure connection is achieved, but the assembly process becomes more complex and time-consuming

Engineering Contradiction:

Improveconnection securityVSAvoidassembly speed

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The pressing-in mechanical assembly process is replaced with a bolted or clipped mechanical fastening system. The planet carrier incorporates mounting features that accept bolts, clips, or other removable fasteners, providing secure mechanical connection without requiring high-pressure pressing equipment, thereby significantly speeding up the assembly process while maintaining connection integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables preassembly of the transmission as a unit, simplifying the assembly process, reducing the risk of components detaching, and eliminating the need for additional installation space or pressing-in processes.

Implementation Method 1

the housing part has at least one lubricant feed, which is designed to fluidically connect a lubricant supply of the transmission to an annular duct

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 2

the planet carrier of the second planetary gear set is arranged on the housing part in a rotationally fixed and axially secured manner

Methodology Applied

Scientific EffectMechanical fastening: Mechanical Fastener

Data Source

PatentUS12292104B2Transmission for a vehicle, and drive train having such a transmission

Publication Date: 2025.05.06 ZF FRIEDRICHSHAFEN AG

AI summary

A transmission (3) for a drive train (2) includes a differential (7) arranged spatially within a housing part (11). The differential includes a first planetary gear set (29) and at least one second planetary gear set (30), which is operatively connected to the first planetary gear set. The housing part (11) includes at least one lubricant feed (15) configured for fluidically connecting a lubricant supply of the transmission (3) to an annular duct (46) formed, at least partially circumferentially, spatially between a planet carrier (32b) of the second planetary gear set (30) and the housing part (11). The planet carrier (32b) of the second planetary gear set (30) is arranged on the housing part (11) in a rotationally fixed and axially secured manner.