Motorcycle Fuel Pump Relocation for Gravity Center and Pipe Length
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Solution Overview
Problem
Existing fuel supply systems for motorcycles face challenges in balancing the vehicle's gravity center, ensuring sufficient road clearance, and minimizing fuel pipe length due to the placement of the fuel pump, which often requires high discharge performance and can lead to issues like percolation and unbalanced mass distribution.
Innovation Solution
A fuel supply device for a straddle-type motorcycle with a fuel pump positioned at the rear of the fuel tank, overlapping with the cylinder assembly, and a fuel injector integrated into the intake air passage, connected by a fuel hose, allowing for a compact engine arrangement and reduced fuel pipe length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fuel pump is mounted on the upper surface of the crankcase behind the cylinder, then the fuel pump can be installed in a conventional position, but the fuel pipe length increases and the gravity center becomes too high
Solution Approach 1:
The fuel pump is relocated from the conventional horizontal mounting position on the crankcase to a vertical arrangement within the fuel tank, utilizing the vertical space above the piston. This dimensional change in spatial arrangement shortens the fuel pipe length while maintaining installation feasibility.
2Device complexity
If the fuel pump is housed inside the side portion of the fuel tank, then the fuel pump can be compactly arranged, but the fuel pipe length increases and the side portion height must be increased
Solution Approach 1:
Instead of placing the fuel pump in the side portion of the fuel tank, the invention positions it at the bottom of the fuel tank with the pump body extending downward. This vertical arrangement in the height dimension allows compact integration without increasing side portion height or fuel pipe length.
Solution Approach 2:
The fuel pump is nested within the fuel tank structure, with the pump body extending downward into the space between the fuel tank bottom and the engine. This nested arrangement utilizes otherwise wasted space, achieving compact integration without increasing overall vehicle height or fuel pipe length.
3Ease of manufacture
If the fuel pump is inserted from the upper surface of the fuel tank, then the fuel pump can be installed, but the fuel pipe length increases and deflection influence is intensified
Solution Approach 1:
Instead of inserting the fuel pump from the upper surface of the fuel tank, the invention inverts the installation direction by positioning the pump at the bottom of the fuel tank with the pump body extending downward. This inverted arrangement shortens the fuel pipe length and reduces deflection influence.
4Device complexity
If the fuel pump is disposed far from the injector, then the fuel pump can be housed in the fuel tank, but the fuel pipe length increases and high discharge performance is required
Solution Approach 1:
The fuel pump is positioned at a specific location at the bottom of the fuel tank that optimizes its proximity to the fuel injector. This localized positioning achieves compact arrangement while minimizing fuel pipe length and reducing the required discharge performance of the fuel pump.
Data Source
AI summary
A straddle type motorcycle includes a frame, an engine mounted on the frame and having a substantially vertical cylinder assembly and an intake air passage extended backward from a rear surface of the cylinder assembly, a fuel tank disposed above the cylinder assembly, and a fuel supply device. The fuel supply device includes a fuel pump disposed at a rear portion of the fuel tank, the fuel pump being overlapped with the cylinder assembly in a longitudinal direction of the motorcycle in a side view of the motorcycle, a fuel injector installed on the intake air passage, and a fuel hose connecting the fuel injector with the fuel pump.