Resin Head Cover Design for Motorcycle Engine Weight Reduction
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Solution Overview
Problem
The challenge is to create an engine for straddled vehicles that inhibits degradation in durability of the resin head cover while making the engine lightweight, as resin head covers thermally deform at high temperatures, limiting their size and thus the weight reduction benefit.
Innovation Solution
The engine design includes a metal cylinder head with a cam support portion and a cam chain compartment, allowing the resin head cover to be extended downward, reducing the metal cylinder head's volume and increasing the resin head cover's volume, while positioning the mating surfaces to avoid thermal deformation and interference with other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the head cover made of resin is increased in size to reduce engine weight, then the weight reduction effect is enhanced, but the head cover thermally deforms at high temperatures, degrading durability
Solution Approach 1:
The patent applies local quality by creating a temperature-dependent material distribution: the lower portion of the head cover (exposed to lower temperatures near the cam chain compartment) is made of resin for weight reduction, while the upper portion (exposed to higher temperatures near the exhaust port) is made of metal for thermal resistance. This local material differentiation allows the head cover to simultaneously achieve weight reduction and thermal durability.
2Volume of stationary object
If the head cover made of resin is increased in size, then the volume of metal cylinder head is reduced, but the resin head cover extends to positions with high thermal exposure, causing thermal deformation
Solution Approach 1:
The patent implements local quality by differentiating material usage based on spatial location and thermal exposure: the lower section of the head cover (in the cam chain compartment with lower temperature) uses resin material to maximize volume replacement and weight reduction, while the upper section (near the exhaust port with high temperature) uses metal material to prevent thermal deformation. This localized material assignment resolves the contradiction between maximizing resin volume and avoiding thermal exposure.
3Weight of moving object
If the mating surface is positioned lower to extend the head cover downward, then weight reduction is improved, but the head cover may be exposed to higher temperatures
Solution Approach 1:
The patent applies local quality by using resin material specifically in the lower portion of the head cover where the mating surface is positioned, taking advantage of the lower temperature environment in the cam chain compartment. The resin head cover portion extends downward to increase volume replacement, while the metal cylinder head and upper head cover portions provide thermal protection. This localized resin application achieves weight reduction without excessive thermal exposure.
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 design enhances the engine's lightweight properties, inhibits thermal deformation of the resin head cover, improves lubrication by warming lubricating oil, and reduces friction, resulting in improved durability and lubrication efficiency.
Implementation Method 1
the cylinder head cover made of resin has a lower thermal conductivity than that made of metal. In other words, the cylinder head cover made of resin has higher heat retaining properties than that made of metal
Implementation Method 2
the first mating surface portion is adjacent to the cam chain compartment having a relatively low temperature in the cylinder head. Therefore, thermal deformation of the head cover is inhibited even when the head cover made of resin is extended to a position adjacent to the cam chain compartment
Data Source
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AI summary
The cylinder head includes a cam support portion supporting the camshaft and a cam chain compartment in which the cam chain is disposed. The cylinder head is made of metal. A head cover is made of resin and is attached to the cylinder head. The cylinder head includes a mating surface to be attached to the head cover. The mating surface includes a first mating surface portion, a second mating surface portion, a third mating surface portion and a fourth mating surface portion. The first mating surface portion is adjacent to the cam chain compartment. In a cylinder axial direction of the cylinder head, a directional side from the head cover to the cylinder head is defined as downward, and the opposite directional side thereof is defined as upward. At least portion of the first mating surface portion is located downward of a lower end of the cam support portion. At least portion of the second mating surface portion, at least portion of the third mating surface portion and at least portion of the fourth mating surface portion are located upward of the lower end of the cam support portion.