Exhaust Purification Device Thermal Insulation Gap
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Solution Overview
Problem
Existing exhaust purification devices face issues where the outer cylinder, in contact with outside air, quickly cools and reduces the temperature of the catalyst support, necessitating engine operation to maintain catalyst efficiency, leading to poor fuel efficiency and emissions.
Innovation Solution
An exhaust purification device with a catalytic converter featuring an inner cylinder with a heat-insulating member at the upstream end and a gap at the downstream end, forming a gas layer between the inner and outer cylinders, allowing exhaust gas to flow and maintain catalyst support warmth, even when the engine is stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the outer cylinder is in contact with outside air to perform heat exchange, then the cooling effect is improved, but the catalyst support temperature decreases and purification efficiency worsens
Solution Approach 1:
The exhaust purification device is divided into an inner cylinder containing the catalyst support and an outer cylinder, with a gap between them. This segmentation allows the inner cylinder to be thermally isolated from the outer cylinder, preventing heat loss to the surrounding air while maintaining effective cooling where needed.
Solution Approach 2:
A heat-insulating member is introduced as an intermediary substance between the inner cylinder and the outer cylinder. This heat-insulating member fills the gap and prevents direct thermal contact, thereby reducing heat loss from the catalyst support to the surrounding air while still allowing for controlled heat exchange in specific areas.
2Reliability
If the engine is operated continuously to maintain catalyst support temperature, then the purification efficiency is improved, but fuel efficiency deteriorates
Solution Approach 1:
The heat-insulating member is pre-installed between the inner and outer cylinders to prevent heat loss before it occurs. This preliminary thermal insulation ensures that the catalyst support maintains its temperature without requiring continuous engine operation, thereby improving fuel efficiency while preserving purification efficiency.
3Temperature
If the inner cylinder thickness is increased to reduce heat loss, then the thermal insulation is improved, but the thermal mass increases and light-off performance worsens
Solution Approach 1:
A heat-insulating member is introduced as an intermediary substance between the inner cylinder and the outer cylinder. This heat-insulating member fills the gap and prevents direct thermal contact, thereby reducing heat loss from the catalyst support to the surrounding air while still allowing for controlled heat exchange in specific areas.
Solution Approach 2:
The exhaust purification device is divided into an inner cylinder containing the catalyst support and an outer cylinder, with a gap between them. This segmentation allows the inner cylinder to be thermally isolated from the outer cylinder, preventing heat loss to the surrounding air while maintaining effective cooling where needed.
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 device effectively keeps the catalyst support warm, improving light-off performance by reducing thermal mass and allowing for efficient exhaust gas purification without continuous engine operation.
Implementation Method 1
an upstream end portion held with no gap via a heat-insulating member having an elastic force to an upstream end portion in a flow direction of the exhaust gas
Implementation Method 2
heat-insulating member having an elastic force
Implementation Method 3
a gas layer is formed by the exhaust gas having flowed into an interior of the inner cylinder from the upstream end portion of the outer cylinder, having been discharged from the downstream end portion of the inner cylinder, and convected from the predetermined gap to an upstream side between the outer cylinder and the inner cylinder
Implementation Method 4
convected from the predetermined gap to an upstream side between the outer cylinder and the inner cylinder
Data Source
Figure 1
Figure 2~3
Figure 4a~4b
AI summary
An exhaust purification device (10) has a catalytic converter (20) between an inlet-side flange (11) positioned on the inlet side of an exhaust gas (G) and an outlet-side flange (12) positioned on the outlet side thereof. The catalytic converter (20) is provided with: an outer cylinder (30) which is welded at the upstream end portion (31) to an exhaust gas inlet (11a) of the inlet-side flange (11) and is welded at the downstream end portion (32) to an exhaust gas outlet (12a) of the outlet-side flange (12); and an inner cylinder (40) that has an upstream end portion (41) held by the upstream side portion of the outer cylinder (30) with no gap and has a downstream end portion (42) disposed at the downstream side of the outer cylinder (30) with a gap (T) and that has housed thereinside a catalyst support (21) for purifying the exhaust gas (G), wherein an opening end (43) is formed at the downstream end portion (42) of the inner cylinder (40) in such a manner as to have a gap (T) with respect to the outer cylinder (30), and a gas layer (H) is formed by the exhaust gas (G) having entered from the exhaust gas inlet (11a), having passed through the opening end (43) of the inner cylinder (40), and convected to an upstream side between the outer cylinder (30) and the inner cylinder (40).