Power-Shift Clutch Decoupling for Motor Vehicle Drive Efficiency

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Solution Overview

Problem

Motor vehicle drive arrangements face inefficiencies due to drag torques when the auxiliary drive train is connected to the main drive train, leading to torque losses during driving.

Innovation Solution

Incorporating a switching unit that decouples the power-shift clutch from the main drive train without differential speed, utilizing a positive-locking clutch and spur gear stage with an idler, and a control unit to manage the clutch and switching unit for optimal torque transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the auxiliary drive train is connected to the main drive train via power-shift clutch, then torque transmission is enabled, but drag torques and torque losses occur during driving

Engineering Contradiction:

Improvetorque transmissionVSAvoiddrag torques

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The drive train is segmented into main drive train and auxiliary drive train that can be independently connected or disconnected. The switching unit allows the auxiliary drive train to be separated from the main drive train when not needed, eliminating drag torques while maintaining torque transmission capability when required.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connection between main drive train and auxiliary drive train is made dynamic through the switching unit and power-shift clutch. The system can transition between connected and disconnected states based on operating conditions, allowing the auxiliary drive train to be decoupled to reduce drag torques during driving.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the power-shift clutch is engaged to connect auxiliary drive train, then drive functionality is provided, but differential speed causes torque losses

Engineering Contradiction:

Improvedrive functionalityVSAvoidtorque losses

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The switching unit acts as an intermediary between the main drive train and power-shift clutch. It provides a positive-locking connection that eliminates differential speed before torque is transmitted through the clutch, preventing torque losses while maintaining drive functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of energy

If switching unit is added to decouple clutch from main drive train, then drag torques are reduced, but device complexity increases

Engineering Contradiction:

Improvedrag torquesVSAvoidswitching unit

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The switching unit is integrated with the existing power-shift clutch mechanism. The positive-locking elements and actuation system are combined with the clutch structure, reducing the overall complexity increase while achieving drag torque reduction through selective decoupling.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9061586B2Motor vehicle drive arrangement

Publication Date: 2015.06.23 DAIMLER TRUCK AG

AI summary

In a motor vehicle drive arrangement having a main drive train for driving a main axle and an auxiliary drive train for driving an auxiliary drive axle, with a power shift clutch for connecting the auxiliary drive train to the main drive train, the auxiliary drive train comprises at least one switching unit for engaging the power shift clutch which is arranged in the power flow in series with the switching unit without a differential speed.