Straddled Vehicle Silencer Sensor Placement
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Solution Overview
Problem
Existing straddled vehicles face challenges in maintaining a compact silencer size while preventing excessive temperature rise of oxygen sensors due to the long distance between catalysts and sensors, leading to enlarged silencer dimensions and potential sensor damage.
Innovation Solution
A straddled vehicle design with a compact silencer configuration, where the upstream catalyst is housed in an outer cylinder and the downstream sensor is supported by a larger cross-sectional area support pipe, reducing the axial distance and temperature exposure, and utilizing a support pipe with an insertion hole to expand exhaust gas and minimize heat transfer to the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the oxygen sensor is brought close to the catalysts to avoid enlargement of the silencer, then the silencer size is reduced, but the temperature of the oxygen sensor rises and approaches the limit temperature
Solution Approach 1:
The patent positions the oxygen sensor at the radial direction of the exhaust pipe rather than along the axial direction, changing the spatial dimension of sensor placement. This allows the sensor to be close to the catalyst in terms of axial distance while being positioned in a location with lower temperature exposure through radial offset
Solution Approach 2:
The patent introduces a heat shield as an intermediary component between the catalyst and the oxygen sensor. This heat shield blocks direct heat transfer from the hot exhaust gas and catalyst to the oxygen sensor, allowing the sensor to be positioned closer to the catalyst without experiencing excessive temperature rise
2Temperature
If the distance from the catalysts to the oxygen sensor is long, then the sensor temperature is reduced, but the silencer becomes large in axial direction or radial direction
Solution Approach 1:
The patent places the oxygen sensor at the radial direction of the exhaust pipe, utilizing the radial dimension rather than extending the axial length. This enables compact silencer design while maintaining adequate thermal separation through the heat shield
Solution Approach 2:
The heat shield serves as a thermal intermediary that allows reduced spacing between catalyst and sensor without compromising sensor temperature management, enabling compact silencer design
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 design achieves a compact silencer size and effectively suppresses sensor temperature rise, ensuring stable operation and precise exhaust gas state detection while maintaining the silencer's compactness and reducing vibration.
Implementation Method 1
a cross-sectional area of the support pipe is greater than a cross-sectional area of the upstream catalyst
Implementation Method 2
an upstream catalyst housed in the silencer and purifying the exhaust gas flowing through the silencer
Data Source
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AI summary
A straddled vehicle includes a silencer 23 disposed at a side of a rear wheel, an upstream catalyst 55 housed in the silencer 23, and a downstream sensor 47 detecting a state of exhaust gas that passed through the upstream catalyst 55. The silencer 23 includes a support pipe 56 supporting the downstream sensor 47 and guiding downstream the exhaust gas that passed through the upstream catalyst 55, and further includes an outer cylinder 62 surrounding the upstream catalyst 55 and the support pipe 56. A distance D1 in an axial direction Da of the upstream catalyst 55 from the upstream catalyst 55 to the downstream sensor 47 is shorter than a length L1 of the upstream catalyst 55 in the axial direction Da of the upstream catalyst 55. A cross-sectional area of the support pipe 56 is greater than a cross-sectional area of the upstream catalyst 55.