Scooter Oxygen Sensor Placement for Exhaust Detection
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Solution Overview
Problem
In scooters with a swing type engine unit and a catalyst disposed below the engine, accurately detecting oxygen concentration near the catalyst is challenging due to the risk of stone chips hitting the oxygen sensor, and existing solutions increase vehicle size by requiring protective covers.
Innovation Solution
The oxygen sensor is positioned between the first and second exhaust pipes, upstream of the silencer, and rearward of the front wheel, with a short distance to the catalyst for accurate detection, and the sensor's placement away from the front wheel reduces stone chip impact, eliminating the need for a protective cover and maintaining vehicle size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the oxygen sensor is disposed below the engine unit near the catalyst for accurate detection, then the measurement precision is improved, but the reliability deteriorates due to stone chip impact
Solution Approach 1:
The oxygen sensor is repositioned from a vertical arrangement (below the engine unit) to a horizontal arrangement (within the exhaust pipe downstream of the catalyst). This spatial reconfiguration maintains close proximity to the catalyst for accurate detection while removing the sensor from the direct path of stone chips thrown by the front wheel, thus resolving the contradiction between measurement precision and reliability
2Reliability
If a protective cover is provided below the oxygen sensor to prevent stone chip hits, then the reliability is improved, but the volume of the vehicle increases
Solution Approach 1:
The oxygen sensor is extracted from its traditional position below the engine unit and relocated to a new position within the exhaust pipe downstream of the catalyst. This extraction eliminates the need for an additional protective cover structure, as the sensor's new location naturally protects it from stone chips while maintaining close proximity to the catalyst for accurate detection, thus resolving the contradiction between reliability and vehicle volume
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 configuration allows for accurate oxygen concentration detection near the catalyst while minimizing stone chip hits and preventing vehicle size increase, maintaining efficient engine operation and compact design.
Implementation Method 1
a catalyst (20) disposed between the first exhaust pipe (21) and the second exhaust pipe (22) and upstream of the silencer (25) in a flow direction of an exhaust gas
Implementation Method 2
an oxygen sensor (40) attached to a portion of the first exhaust pipe (21) closer to the catalyst (20) than an intermediate position of the first exhaust pipe (21)
Data Source
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AI summary
Provided is a scooter including a swing type engine unit and a catalyst disposed below the engine unit and capable of accurately detecting an oxygen concentration of an exhaust gas near the catalyst, inhibiting hitting of stone chips against an oxygen sensor, and suppressing an increase in the vehicle size. The scooter 1 includes a catalyst 20 disposed below an engine unit 10 and an oxygen sensor 40 attached to a portion of a first exhaust pipe 21 closer to the catalyst 20 than an intermediate position of the first exhaust pipe 21. A body portion 42 of the oxygen sensor 40 is disposed above a lower end 21e of the first exhaust pipe 21. At least a portion of the catalyst 20 overlaps the engine unit 10 in a vehicle bottom view. The oxygen sensor 40 is disposed rearward of a pivot shaft 6 and rearward of a cylinder body 12. The oxygen sensor 40 and an under cover 5 do not overlap each other in a vehicle bottom view and overlap each other in a vehicle front view.