Double-Wall Muffler Sensor Port Sealing for Thermal Wall Movement
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Solution Overview
Problem
The existing design of double-walled engine exhaust mufflers poses a fire hazard due to the large opening required for sensor access, which allows dirt and debris to enter and come into contact with high temperatures, especially in environments with high dirt or debris particles.
Innovation Solution
A sealing assembly for the sensor port of a double-walled muffler, comprising an outer plate, a washer-type element, and optionally an inner plate, which allows for lateral movement of the washer relative to the plates, ensuring the sealing function remains intact even with radial or lateral movement of the boss due to temperature differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large opening is provided in the outer wall for sensor access, then the sensor can be accessed and connected to a measurement unit, but dirt and debris can enter and come into contact with high temperatures causing a fire hazard
Solution Approach 1:
A sealing assembly comprising an outer plate, washer-type element, and inner plate is introduced as an intermediary component. The outer plate is fixed to the outer wall with an opening, the inner plate is fixed to the boss, and the washer-type element seals between them. This intermediary sealing structure allows sensor access while preventing dirt and debris from entering the high-temperature zone.
2Reliability
If the opening in the outer wall is made larger to accommodate wall movement, then the relative shift between inner and outer walls can occur without damaging the sensor, but the opening becomes larger allowing more dirt and debris to enter
Solution Approach 1:
The sealing assembly acts as an intermediary that decouples the sealing function from the movement accommodation function. The washer-type element provides sealing while the entire assembly allows lateral movement of the boss relative to the outer wall without compromising the seal, thus protecting against both wall movement damage and dirt intrusion.
Solution Approach 2:
The sealing assembly is designed to be dynamic rather than rigid. The washer-type element can move laterally relative to the plates, and the entire assembly can accommodate the radial and lateral movements of the boss relative to the outer wall caused by thermal expansion, maintaining sealing effectiveness throughout the movement range.
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 sealing assembly effectively closes off the sensor port from the exterior while allowing for necessary movement of the boss relative to the outer wall, thereby preventing dirt and debris from entering and reducing the risk of a fire hazard.
Implementation Method 1
Due to the gap between the walls and even more so when the gap is filled with insulation material, an important temperature difference appears between the inner and outer walls of the muffler, once the muffler reaches an operational temperature. As a consequence of this, the inner and outer wall undergo important dimensional shifts with respect to each other
Data Source
Figure 1~2b
Figure 3a~3b
Figure 4a~4b
AI summary
The invention is related to a sealing assembly (15) for a sensor port (4) of a double-walled muffler (1), and to a muffler (1) provided with such a sealing assembly (15). The assembly comprises at least an outer plate (21) and a washer-type element (22). The washer-type element has a planar portion (25) provided with an aperture (26), and a tube portion (27) protruding from the edge of the aperture. The assembly is mounted on a sensor port provided with a boss (12) fixed to the inner wall (10) of the double muffler wall, and with an opening (13) in the outer wall (11) surrounding the boss (12). The tube portion (27) is fitted over the boss (12) and the assembly is fixed to the outer wall (11) of the muffler. Any radial or lateral movement of the boss (12) relative to the outer wall (11) is able to take place without losing the sealing function, due to the lateral freedom of movement of the washer-type element (22) relative to the plate or plates, and due to the fact that the boss (12) is able to move relative to the tube portion (27) in a direction perpendicular to the plate or plates (20,21).