Outboard Motor Catalyst Axial Expansion Structure
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Solution Overview
Problem
Conventional outboard motor catalyst installations are prone to damage due to thermal expansion, as the catalyst is not adequately supported to accommodate dimensional changes between the catalyst, housing, and exhaust gas guide.
Innovation Solution
The catalyst installation structure for an outboard motor includes a catalyst storage chamber integrated with the cylinder block, allowing the catalytic converter to expand axially, with at least one side end fitted to the chamber, enabling relative movement and preventing damage from thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst is disposed in a manner supported in a vertical direction between a catalyst housing portion and an exhaust gas guide, then the catalyst can be securely positioned, but the catalyst may be destroyed due to thermal expansion
Solution Approach 1:
The patent applies the dynamics principle by making the catalyst support structure movable in the axial direction. The support structure is designed to slide within the exhaust passage, allowing it to dynamically adjust its position to accommodate thermal expansion of the catalyst during engine operation, thereby preventing catalyst destruction while maintaining secure positioning.
Solution Approach 2:
The patent applies parameter changes by allowing the support structure to change its axial position parameter in response to temperature changes. As the catalyst heats up and expands, the support structure moves axially to maintain proper clearance and prevent damage, adapting the mechanical parameters of the system to thermal conditions.
2Stability of the object's composition
If the catalytic converter is firmly fixed to prevent movement, then positioning stability is improved, but thermal expansion causes damage
Solution Approach 1:
The support structure is designed with dynamic characteristics, allowing controlled movement in the axial direction while maintaining lateral stability. This enables the catalyst to expand freely along the axis during thermal cycles without compromising its positional stability or risking damage from constrained expansion.
3Strength
If the catalyst is allowed to move freely to accommodate thermal expansion, then catalyst damage is prevented, but positioning stability deteriorates
Solution Approach 1:
The support structure is segmented into multiple components that work together: a sliding portion that allows axial movement, a fixing portion that maintains lateral position, and sealing elements that maintain exhaust gas flow paths. This segmentation enables independent control of movement freedom and positional stability.
Solution Approach 2:
The support structure acts as an intermediary between the catalyst and the exhaust passage wall. It provides a controlled interface that permits thermal expansion while maintaining stable positioning through its designed movement constraints and sealing mechanisms.
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 ensures the catalytic converter can move axially with thermal expansion, preventing damage and improving durability, while maintaining hermetic sealing and enhancing cooling efficiency through a direct cooling water passage.
Implementation Method 1
a catalytic converter for purifying or cleaning up an exhaust gas (or merely exhaust) discharged from a four-stroke-cycle engine
Implementation Method 2
in an event when a relative change in dimension in an axial direction is caused between the catalyst, the catalyst housing portion and the exhaust gas guide, the catalyst is thermally excessively expanded
Data Source
AI summary
An outboard motor equipped with a four-stroke engine and provided with a catalyst installation structure, in which an exhaust passage is connected to the exhaust ports of the plurality of the cylinders to lead the exhaust gas out of the engine is provided with a catalyst storage chamber configured to store a catalytic converter for cleaning up the exhaust gas, the exhaust passage being integrally formed to the cylinder block, and the catalytic converter is mounted to the catalyst storage chamber by being inserted from a lower side thereof in such a manner as that at least one side end portion thereof is fitted to the catalyst storage chamber to permit expansion of the catalytic converter in an axial direction thereof.