Motorcycle Intake Device with Overlapping Passage
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Solution Overview
Problem
In straddle-type motorcycles, the rear cushion unit obstructs the formation of a straight intake air passage, leading to increased intake air resistance and reduced suspension stroke and road clearance, while existing intake air temperature sensors face precision issues due to non-uniform air flow and potential interference from exhaust heat.
Innovation Solution
The intake device features an inverted rear cushion unit with an overlapping intake air passage that increases the passage area and suspension stroke, and an intake air temperature sensor positioned on a connecting pipe within the intake air passage to ensure uniform temperature detection and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the intake air passage is formed straight by disposing it above the upper mounting portion of the rear cushion unit, then the intake air resistance is reduced, but the entire length of the rear cushion unit must be shortened reducing the suspension stroke
Solution Approach 1:
The intake air passage is routed through the width direction of the vehicle body rather than the vertical direction, allowing it to pass through the swing arm which spans laterally. This dimensional change enables the air passage to bypass the rear cushion unit without compromising its length or suspension stroke.
2Loss of energy
If the position of the air cleaner is raised to form a straight intake air passage, then the intake air resistance is reduced, but the rider's seat must be brought up deteriorating the riding comfort
Solution Approach 1:
The air cleaner remains in its original position under the rider's seat, but the intake air passage is routed through the width direction via the swing arm. This lateral routing path allows the air passage to be straight without raising the air cleaner or rider's seat, preserving riding comfort while reducing intake air resistance.
3Length of moving object
If the position of the lower end of the rear cushion unit is lowered to increase the entire length, then the suspension stroke is increased, but the minimum road clearance is lowered deteriorating the off-road running performance
Solution Approach 1:
The intake air passage is routed through the swing arm in the width direction, allowing the rear cushion unit to maintain its full length and suspension stroke without compromising road clearance. The lateral routing path through the swing arm provides sufficient space for the air passage without requiring the lower end of the rear cushion unit to be lowered.
4Reliability
If the intake air temperature sensor is mounted on the air cleaner box body, then the sensor is protected, but the temperature detection precision is reduced due to non-uniform air flow and box-like shape
Solution Approach 1:
The intake air temperature sensor is extracted from the air cleaner box body and mounted directly on the intake air passage. This extraction allows the sensor to be positioned in the uniform flow of intake air, improving temperature detection precision while the sensor remains protected through its integration with the intake air passage structure.
5Reliability
If the intake air temperature sensor is mounted inside the air cleaner box, then the sensor is protected, but the temperature detection precision is reduced due to detection of remaining air in the box
Solution Approach 1:
The intake air temperature sensor is extracted from the air cleaner box interior and mounted on the intake air passage. This positioning ensures the sensor detects the temperature of air actually flowing through the passage into the combustion chamber, eliminating the issue of detecting stagnant remaining air while maintaining sensor protection through proper mounting.
6Reliability
If the intake air temperature sensor is mounted on the air cleaner box body, then the sensor is protected, but the sensor is affected by heat from the exhaust system
Solution Approach 1:
The intake air temperature sensor is extracted from the air cleaner box body mounting location and repositioned on the intake air passage. This relocation removes the sensor from the thermal influence zone of the exhaust system while the sensor remains protected and integrated with the intake air passage structure, eliminating heat interference.
Data Source
AI summary
A motorcycle includes an engine having a substantially vertical cylinder assembly and disposed in a front half of a vehicle body frame, an inverted type rear cushion unit disposed behind the engine in substantially vertical posture, an air cleaner disposed behind the rear cushion unit and below a rider's seat, and an intake air passage connecting air an intake port formed in a rear portion of the cylinder assembly and the air cleaner each other. The intake air passage, i.e., connecting pipe, is arranged so as to be overlapped with an upper portion of the rear cushion unit in a side view of the motorcycle. A cross section shape of the connecting pipe is a vertically long shape in which its longitudinal size is greater than its lateral size.