Straddle Vehicle Battery Mounting on Rear Fender
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Solution Overview
Problem
In straddle-type vehicles, installing a larger engine complicates air cleaner and fuel tank volume requirements, making it difficult for riders to place their feet on the ground due to battery positioning constraints, which limits the size of these components and affects vehicle stability.
Innovation Solution
The vehicle design includes a rear fender with a second upper surface protruding upward and a recessed second lower surface, allowing the battery to be positioned behind the fuel tank with its largest surface facing the second upper surface, reducing stress and enabling larger air cleaner and fuel tank sizes without raising the seat height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the air cleaner volume is increased to support a larger engine, then the engine power is improved, but the battery has to be disposed at a higher position which makes it difficult for the rider to place a foot on the ground
Solution Approach 1:
The patent repositions the battery from a vertical arrangement (below the seat) to a horizontal arrangement (on the rear fender), utilizing the lateral dimension of the vehicle structure. This dimensional change allows the air cleaner to be enlarged vertically without compromising foot placement, as the battery no longer occupies the vertical space beneath the seat.
Solution Approach 2:
The battery is nested on the rear fender structure, which itself is part of the vehicle's frame system. This nesting approach allows efficient use of available space by placing the battery on an existing structural element (the rear fender) rather than requiring separate dedicated space, thereby enabling the air cleaner to be enlarged without affecting overall vehicle height.
2Volume of stationary object
If the battery is disposed on the rear fender to ensure air cleaner and fuel tank volume, then the component volumes are improved, but the contact area between the battery and rear fender increases causing stress from oscillations to be applied to the battery
Solution Approach 1:
The patent introduces a localized cushioning structure (foam material or rubber sheet) at the specific contact interface between the battery and rear fender. This local quality enhancement provides stress absorption and vibration isolation precisely where needed, without affecting the overall battery positioning or the volume of surrounding components.
Solution Approach 2:
The cushioning material is pre-installed between the battery and rear fender to provide advance protection against oscillation-induced stress. This beforehand cushioning approach prevents stress transmission to the battery before the oscillations occur during vehicle operation, thereby protecting the battery without requiring design changes to the battery itself.
3Ease of operation
If the battery is disposed in a recumbent position to reduce the dimension in the up-down direction, then the seat height is maintained, but the contact area between the battery and rear fender increases which applies stress to the battery
Solution Approach 1:
The cushioning structure is applied locally at the battery-rear fender interface to compensate for the increased contact area resulting from the recumbent battery position. This localized stress absorption allows the battery to be oriented horizontally (maintaining seat height) while protecting against the increased stress that would otherwise be transmitted during vehicle oscillations.
Data Source
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AI summary
A straddle-type vehicle includes: an air cleaner 68 including an upper end 68T located higher than a lower end 64B of a fuel tank 64; a rear fender 70 including a second upper surface 72U protruding upward from a first upper surface, and a second lower surface 72B located on a back of the second upper surface 72U and recessed upward from a first lower surface located on a back of the first upper surface; and a battery 80 disposed behind the fuel tank 64 and over the second upper surface 72U. A largest surface 81A of the battery 80 faces the second upper surface 72U. A longest side 82A of the battery 80 in a plan view extends in a vehicle width direction. A front end 80UF of an upper surface 80U of the battery 80 is located lower than a rear end 80UR of the upper surface 80U.