Urea Injector Attachment Rib for Exhaust Flow Control
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Solution Overview
Problem
The reverse flow of exhaust gas towards the nozzle hole of the urea water injector in an exhaust structure causes adhesion of urea, leading to decreased ejection efficiency and insufficient ammonia supply to the SCR catalyst, resulting in poor exhaust gas purification.
Innovation Solution
An injector attachment member with a cylindrical body and ribs on its inner peripheral surface is used to change the flow direction of exhaust gas, preventing accumulation and adhesion of urea near the nozzle hole, ensuring efficient urea water ejection and sufficient ammonia supply to the SCR catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the urea water injector is directly attached to the exhaust pipe, then the structure is simple, but reverse flow of exhaust gas causes urea adhesion to the nozzle hole
Solution Approach 1:
The patent introduces an attachment member as an intermediary component between the exhaust pipe and urea water injector. This attachment member includes a flow direction changing portion that redirects exhaust gas flow, preventing reverse flow from reaching the nozzle hole. The intermediary structure resolves the contradiction by adding a controlled element that eliminates the harmful reverse flow effect while maintaining overall system functionality.
2Ease of operation
If the exhaust gas flow direction is not controlled, then the flow path is straightforward, but reverse flow pushes urea water back toward the nozzle hole causing adhesion
Solution Approach 1:
The attachment member is designed with a flow direction changing portion that proactively redirects exhaust gas flow before it can reach the nozzle hole and cause reverse flow. This preliminary anti-action prevents the harmful effect of urea adhesion by altering the exhaust gas flow direction in advance, countering the potential reverse flow problem before it manifests.
3Device complexity
If no flow direction control is provided, then the device structure is simple, but insufficient ammonia supply occurs due to urea adhesion
Solution Approach 1:
The attachment member serves as a mediating structure that ensures proper exhaust gas flow direction, thereby guaranteeing sufficient ammonia supply to the SCR catalyst. By preventing reverse flow and urea adhesion through its flow direction changing portion, the intermediary component maintains the productivity requirement without significantly complicating the overall device structure.
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
The solution effectively suppresses urea adhesion, maintaining efficient urea water ejection and ensuring sufficient ammonia supply to the SCR catalyst, thereby improving exhaust gas purification efficiency.
Implementation Method 1
an inner peripheral surface of the injector attachment member is provided with a rib that changes a flow direction of the exhaust gas from the other opening portion toward the one opening portion to a flow direction from the one opening portion toward the other opening portion
Implementation Method 2
SCR (selective catalytic reduction) catalyst that is provided on a downstream side of an ejection position of the urea water inside the exhaust pipe
Implementation Method 3
the urea water ejected from the urea water injector is hydrolyzed by the heat of the exhaust gas. Ammonia generated as a result of this is supplied to the SCR catalyst
Data Source
AI summary
The exhaust structure comprises an exhaust pipe through which exhaust gas flows, a urea water injector that injects urea water, a SCR catalyst provided downstream of the injection position of the urea water, and an attachment member for fixedly attaching the urea water injector to the exhaust pipe. The attachment member is a cylindrical body passing through in the axial direction, and is attached to the exhaust pipe such that a nozzle hole of a urea water injector is disposed in one opening part and the other opening part faces the inside of the exhaust pipe on the upstream side of the SCR catalyst. The inner peripheral surface of the attachment member is provided with a rib that causes exhaust gas flowing from the other opening part to the one opening part to change direction so as to flow from the one opening part to the other opening part.