Secondary Air System for Low-Emission Internal Combustion Engine

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Solution Overview

Problem

Existing internal combustion engines struggle to achieve particularly low-emission operation.

Innovation Solution

A secondary air system is connected to the intake tract at both upstream and downstream points of the compressor, allowing air to be branched off and introduced into the exhaust tract as secondary air, utilizing a secondary air pump to convey pre-compressor air, enabling efficient secondary air injection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a single branch point downstream of the compressor is used for secondary air injection, then the system structure is simple, but the amount of secondary air that can be introduced into the exhaust tract is limited

Engineering Contradiction:
Improveamount of secondary airVSAvoidsystem structure
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The intake tract is segmented into two separate branch points: one downstream of the compressor (first branch point) and one upstream of the compressor (second branch point). This segmentation allows independent extraction of air at different stages of compression, enabling the secondary air system to introduce a larger total amount of air into the exhaust tract while maintaining manageable system complexity through modular branching architecture.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If air is branched off only downstream of the compressor, then compressor air can be utilized, but air upstream of the compressor cannot be used for secondary air injection

Engineering Contradiction:
Improveoperating range adaptabilityVSAvoidavailable air for secondary injection
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The secondary air system is designed with universal air extraction capability by implementing two branch points that can draw air from different locations in the intake tract. The first branch point extracts compressed air for certain operating conditions, while the second branch point extracts uncompressed air for other conditions. This multi-functional design allows the system to adapt to various operating ranges and maximize the quantity of air available for secondary injection regardless of engine load or speed.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If the secondary air system only extracts air downstream of the compressor, then the system is simple to control, but secondary air injection is insufficient across all operating ranges

Engineering Contradiction:
Improvesecondary air injection efficiencyVSAvoidcontrol system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The secondary air system incorporates dynamic control through selectively operable first and second extraction lines with associated control valves. The system can dynamically switch between extracting air from upstream or downstream of the compressor based on real-time operating conditions. This dynamic architecture significantly improves secondary air injection efficiency across all operating ranges while maintaining relatively simple control logic that activates only the appropriate extraction line based on pre-defined operational criteria.

Inventive Principle:
Principle #15Dynamics

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

This configuration allows for a large amount of secondary air to be introduced into the exhaust tract across all operating ranges, resulting in particularly low-emission operation of the internal combustion engine.

Implementation Method 1

a compressor is arranged to compress the air flowing through the intake tract

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

The secondary air system has a secondary air pump, by means of which the air branched off at the second branch point can be conveyed through the secondary air system

Methodology Applied
Scientific EffectPumping: Pump

Data Source

PatentEP4405574B1Internal combustion engine for a motor vehicle, in particular for a car
Publication Date: 2025.10.01 MERCEDES BENZ GROUP AG
  • EP4405574B1 patent drawingFigure 1

AI summary

The invention relates to an internal combustion engine (10) for a motor vehicle, comprising an intake tract (16) through which air can flow and in which a compressor (20) is arranged for compressing the air, an exhaust gas tract (24) through which exhaust gas can flow, and a secondary air system (52) that is fluidically connected to the exhaust gas tract (24) at an inlet point (E) and to the intake tract (16) at a branching point (A1) which is arranged downstream of the compressor (20) and at which at least one part of the air compressed by the compressor (20) can be branched off from the intake tract (16) by means of the secondary air system (52) and can be introduced into the exhaust gas tract (24) at the inlet point (E) as secondary air. The secondary air system (52) is also fluidically connected to the intake tract (16) at a second branching point (A2) arranged upstream of the compressor (20) and comprises a secondary air pump (54).