Engine Decompression Mechanism Compactness via Segmented Flange
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine decompression mechanisms that are disposed between the ends of a camshaft face limitations in compactness due to restricted attachment locations for support shafts, leading to increased engine size and complexity.
Innovation Solution
A decompression mechanism is implemented with a flange press-fitted onto the camshaft, allowing for flexible placement of a pivot pin and supporting a weight and decompression cam, which enhances compactness by separating the flange from the camshaft and utilizing a return spring for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the support shaft is attached to the exhaust cam at a location that ensures attachment strength, then the attachment strength is improved, but the degree of freedom for disposing the pivot pin deteriorates due to restricted attachment locations
Solution Approach 1:
The exhaust cam is divided into a camshaft portion and a cam lobe portion, with the support shaft attached to the camshaft portion at a location that does not overlap with the cam lobe in the axial direction. This segmentation allows the pivot pin to be disposed at a location ensuring both attachment strength and degree of freedom, resolving the technical contradiction between attachment strength and pivot pin disposal flexibility.
2Adaptability or versatility
If the size of the exhaust cam is increased to resolve the restriction of support shaft disposition, then the degree of freedom for disposing the support shaft is improved, but the size of the cam shaft and valve mechanism increases, leading to increased engine size
Solution Approach 1:
The support shaft attachment location is positioned in the axial direction of the exhaust cam at a location that does not overlap with the cam lobe, utilizing the axial dimension to resolve the restriction of support shaft disposition. This approach increases the degree of freedom for support shaft disposal without increasing the radial size of the exhaust cam, thereby avoiding an increase in engine size.
3Length of moving object
If the decompression mechanism is disposed between both end portions of the cam shaft to make it more compact, then the axial compactness is improved, but the attachment location for the support shaft is restricted due to the small dimension of the base circle portion
Solution Approach 1:
The exhaust cam is segmented into a camshaft portion and a cam lobe portion, allowing the support shaft to be attached to the camshaft portion at a location that does not overlap with the cam lobe in the axial direction. This segmentation enables the decompression mechanism to be disposed between both end portions of the cam shaft, achieving axial compactness while maintaining attachment location freedom through the separated functional zones.
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 improves the degree of freedom for pivot pin placement, reduces engine size, and maintains efficient decompression functionality without increasing the camshaft and valve mechanism sizes, thereby making the engine more compact.
Implementation Method 1
a flange (41) which is press-fitted onto the cam shaft (26)
Implementation Method 2
The weight (42) is supported on the flange (41) via the pivot pin (46) so as to be rotatable between a closed state and an open state
Implementation Method 3
a decompression cam (43) which switches between a state of coming into contact with a valve mechanism and a state of not coming into contact with the valve mechanism in response to a rotation of the weight (42)
Data Source
AI summary
A decompression mechanism includes a flange, a pivot pin, a weight, and a decompression cam. The flange is a body separate from the cam shaft and is press-fitted onto the cam shaft. The pivot pin is attached to the flange. The weight is supported on the cam shaft in a rotatable manner between a closed state and an open state. The decompression cam switches between a state of coming into contact with a valve mechanism and a state of not coming into contact with the valve mechanism in response to the rotation of the weight.