Exhaust Pipe Curvature and Swirl Flow for Catalyst Heating

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Solution Overview

Problem

Conventional exhaust pipe structures for internal combustion engines result in uneven exhaust gas flow into the purifying catalyst device, leading to inadequate temperature rise and potential catalyst deterioration due to long pipe lengths and uneven gas distribution.

Innovation Solution

The exhaust pipe structure features a curved main part with an offset inlet and an obliquely extending introduction part that generates swirl flow, connecting to the outer circumferential side of the purifying catalyst device, optimizing gas flow and reducing pipe length for rapid temperature rise and improved catalyst exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the exhaust pipe is formed to greatly bend downwards after extending in a substantially horizontal direction, then the exhaust pipe can connect to the exhaust purifying catalyst device arranged vertically, but the length of the exhaust pipe becomes long, increasing heat capacity and preventing rapid temperature rise of the catalyst

Engineering Contradiction:

Improveconnectability to vertically arranged catalyst deviceVSAvoidexhaust pipe length

Core Design Contradiction:

Ease of operationVSLength of moving object

Solution Approach 1:

The exhaust pipe main body is configured to curve in a specific arc shape rather than bending sharply downwards. This curved configuration shortens the pipe length while maintaining the ability to connect to the vertically arranged catalyst device, thereby reducing heat capacity and enabling rapid catalyst temperature rise.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of operation

If the exhaust pipe extends horizontally and connects to the upper end of the vertically arranged catalyst device, then the catalyst device can be arranged in a compact vertical orientation, but the exhaust gas flow becomes concentrated on the outer side of the curved part, causing uneven flow distribution

Engineering Contradiction:

Improvevertical arrangement of catalyst deviceVSAvoiduniformity of exhaust gas flow

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The exhaust pipe introduction portion is asymmetrically configured with respect to the catalyst device opening. The introduction portion extends obliquely and connects to the outer circumferential side of the catalyst device, creating an asymmetric flow path that distributes exhaust gas uniformly across the catalyst opening rather than concentrating it on one side.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The exhaust pipe introduction portion is positioned at a different vertical level than the catalyst device opening, creating a height difference. This dimensional offset allows the introduction portion to extend obliquely and distribute exhaust gas more uniformly across the catalyst opening, preventing flow concentration.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Stability of the object's composition

If a gas rectifying part is added to the inner wall of the curved part to correct flow unevenness, then exhaust gas flow uniformity improves, but the exhaust pipe structure becomes more complex and installation space requirements increase

Engineering Contradiction:

Improveuniformity of exhaust gas flowVSAvoidexhaust pipe structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The flow distribution function is merged into the exhaust pipe main body itself rather than being a separate component. The curved configuration and oblique introduction portion of the exhaust pipe directly create uniform flow distribution, eliminating the need for separate gas rectifying parts and reducing structural complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 design effectively suppresses uneven gas flow, ensures uniform exposure to the catalyst, and allows for a shorter, more efficient exhaust pipe structure that rapidly raises the temperature of the purifying catalyst while optimizing space usage and detection precision.

Implementation Method 1

the exhaust pipe introduction part has a space from an end face of the end of the exhaust purifying catalyst device, and extends obliquely to a side of the exhaust purifying catalyst device from an end of the exhaust pipe main part on a side of the exhaust purifying catalyst device until an outer circumferential end of the exhaust purifying catalyst device, thereby the exhaust gas becoming swirl flow and flowing into the exhaust purifying catalyst device

Methodology Applied

Scientific EffectSwirl flow: Vortex Ring

Data Source

PatentUS10557398B2Exhaust pipe structure for internal combustion engine

Publication Date: 2020.02.11 HONDA MOTOR CO LTD

AI summary

The present invention discloses an exhaust pipe structure for an internal combustion engine in which a tubular exhaust purifying catalyst device including an exhaust purifying catalyst is disposed in a vicinity of the internal combustion engine within an engine room. The exhaust pipe structure comprises an exhaust pipe main part which curves from a side of the internal combustion engine and extends towards an end of the exhaust purifying catalyst device in a center axis line direction of the exhaust purifying catalyst device and an exhaust pipe introduction part that connects the exhaust pipe main part and the end of the exhaust purifying catalyst device, and introduces exhaust gas from the exhaust pipe main part into the exhaust purifying catalyst device.