Decompressor Shaft Falling-Off Prevention Pin Design
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Solution Overview
Problem
Existing decompressors for internal combustion engines are prone to falling off during maintenance, making maintenance work difficult due to the removable design of the decompression shaft and potential disengagement of the eccentric protruding portion from the recessed groove.
Innovation Solution
A decompressor design where the decompression shaft is supported to rotate freely, with a falling-off prevention pin engaging the shaft and a bearing-restriction portion preventing axial movement, ensuring the shaft remains in place during maintenance by blocking the pin insertion hole and maintaining engagement with the decompression plunger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the decompression shaft is designed to be removably inserted in the insertion hole, then the ease of maintenance is improved, but the reliability deteriorates because the shaft may fall out during maintenance work
Solution Approach 1:
The falling-off prevention pin is pre-installed in the pin insertion hole before the decompression shaft is removed. This preliminary action ensures that when the shaft is later reinstalled, it cannot fall out during maintenance operations, while still allowing easy removal when needed.
Solution Approach 2:
The falling-off prevention pin acts as an intermediary element between the decompression shaft and the camshaft. It engages with the shaft to prevent axial displacement and falling off, while allowing the shaft to be easily removed when required for maintenance.
2Ease of operation
If the decompression shaft is made removable for maintenance, then the ease of operation is improved, but the stability of the object's composition deteriorates because the eccentric protruding portion may disengage from the recessed groove
Solution Approach 1:
The falling-off prevention pin is installed in advance in the pin insertion hole to prevent the decompression shaft from disengaging from the eccentric protruding portion during maintenance operations. This ensures stable engagement while maintaining ease of removal.
3Ease of manufacture
If the bearing is allowed to move freely in the axial direction, then the ease of assembly is improved, but the reliability deteriorates because the falling-off prevention pin may drop off
Solution Approach 1:
The bearing-restriction portion serves as an intermediary structure that limits the axial movement of the bearing. It prevents the bearing from moving enough to open the pin insertion hole, thereby preventing the falling-off prevention pin from dropping off while still allowing free rotation.
Solution Approach 2:
The bearing-restriction portion creates a localized constraint on the bearing's axial movement. This local restriction prevents the pin insertion hole from opening completely, ensuring reliable engagement of the falling-off prevention pin while maintaining overall ease of assembly.
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
Prevents the decompression shaft from falling off during maintenance, allowing for safe and efficient maintenance operations without compromising the decompression function.
Implementation Method 1
The bearing is fitted to the camshaft so as to allow the camshaft to rotate freely
Implementation Method 2
the decompression shaft is inserted and fitted into an insertion hole so as to be rotatable relative to the camshaft
Implementation Method 3
By engaging a falling-off prevention pin with the decompression shaft while allowing the decompression shaft to rotate, the decompression shaft is prevented from moving in the axial direction
Data Source
AI summary
A decompressor for an internal combustion engine that is capable of preventing the dropping-off of the decompression shaft during maintenance work includes a falling-off prevention pin inserted into a pin insertion hole having an opening to the outer circumferential surface of a camshaft and intersecting, at least partially, an insertion hole. A decompression shaft is inserted and fitted into the insertion hole. The falling-off prevention pin engages with the decompression shaft while the decompression shaft is allowed to rotate. The decompression shaft is prevented from moving in the axial direction of the decompression shaft. The opening of the pin insertion hole of the camshaft into which the falling-off prevention pin is inserted is blocked by a bearing. A swing portion includes a bearing-restriction portion formed so as to protrude towards the bearing. The bearing-restrict portion restricts the movement of the bearing in the axial direction of the camshaft.