Exhaust Pipe Earth Circuit for Oxygen Sensor Wiring
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Solution Overview
Problem
Existing configurations for attaching an oxygen sensor to a motorcycle's exhaust system require a dedicated earth wire, which increases costs and complexity, especially when conductivity between the exhaust pipe and engine is not ensured, necessitating a reliable, cost-effective, and easy-to-form earth circuit without a direct earth wire connection to the battery.
Innovation Solution
The oxygen sensor is attached to the exhaust pipe with an earth connection portion near the vehicle-body frame, utilizing a sensor-side earth wire to connect the exhaust pipe to the vehicle-body frame, which then connects to the engine and battery via an engine-side earth wire, eliminating the need for a direct earth wire between the sensor and battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated earth wire is used to connect the oxygen sensor directly to the battery, then the earth circuit reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The exhaust pipe serves as an intermediary conductive path between the oxygen sensor and the vehicle body frame. The sensor body is electrically connected to the exhaust pipe, which then connects to the vehicle body frame, eliminating the need for a dedicated earth wire while maintaining earth circuit functionality
Solution Approach 2:
The exhaust pipe is given a dual function: it serves both as the exhaust gas conduit and as the earth circuit conductor. This multi-functional approach allows the same component to perform multiple roles, reducing the need for additional dedicated earth wiring
2Device complexity
If the exhaust pipe is used as part of the earth circuit without a dedicated earth wire, then the cost and complexity are reduced, but the earth circuit reliability deteriorates when conductivity between exhaust pipe and engine is not ensured
Solution Approach 1:
A conductive gasket is pre-installed between the exhaust pipe and the vehicle body frame mounting point to ensure electrical conductivity is established in advance. This preliminary conductive path guarantee ensures that when the exhaust pipe is mounted, the earth circuit is automatically established without requiring additional conductivity verification or special surface treatments
Solution Approach 2:
The conductive gasket acts as an intermediary element that ensures reliable electrical contact between the exhaust pipe and the vehicle body frame. It mediates the electrical connection, guaranteeing conductivity even when surface conditions or mounting variations occur
3Quantity of substance
If the oxygen sensor is attached to the exhaust pipe, then the number of sensors needed is reduced, but the earth circuit formation becomes more difficult without dedicated earth wire
Solution Approach 1:
The exhaust pipe mounting structure automatically provides the earth circuit connection. When the exhaust pipe is mounted to the vehicle body frame using the conductive gasket, the electrical connection is established automatically as part of the mechanical assembly process, eliminating the need for separate earth wire installation steps
Solution Approach 2:
The mechanical assembly of the exhaust pipe and the electrical earth circuit formation are merged into a single operation. The same mounting bolts and conductive gasket that secure the exhaust pipe also establish the electrical connection, combining two functions into one integrated solution
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 forms a reliable, easily assembled, and cost-effective earth circuit, even when conductivity between the exhaust pipe and engine is not ensured, with a shorter sensor-side earth wire length and improved assemblability, while maintaining the oxygen sensor's heat radiation characteristics.
Implementation Method 1
the vehicle-body frame and an engine-side earth wire form an earth circuit, thereby enabling a configuration in which a dedicated earth wire directly connecting the oxygen sensor and the battery is not needed
Data Source
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AI summary
In a saddle-ride type vehicle, an exhaust pipe 33 is connected to an exhaust port of an engine 30, and an O2 sensor 50 is attached near this connection portion. The O2 sensor 50 is connected with a positive terminal of a battery 66. The exhaust pipe 33 extends rearward and is supported by a pivot plate 15 at a vehicle-body attachment stay 46. An earth connection portion 47 is provided integrally with a portion of the vehicle-body attachment stay 46, and a terminal 61 of a sensor-side earth wire 60 is connected to the earth connection portion 47. The pivot plate 15 is part of a vehicle-body frame 10, and is electrically connected to the engine 30 supported by the vehicle-body frame 10. The engine is connected to a negative terminal of the battery 66 by an engine-side earth wire 67. Thus, the exhaust pipe 33 serves as part of the earth wire. This facilitates wiring of an earth wire for an oxygen sensor.