Engine Decompressor Axial Movement Control
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Solution Overview
Problem
Existing engine decompressors face issues with smooth operation at very low temperatures due to increased viscosity of lubricating oil and pressure, which can lock the decompressor pin operating shaft, preventing normal decompression.
Innovation Solution
Incorporation of a restricting member, such as a thrust receiving plate, to limit axial movement of the decompressor pin operating shaft and prevent contact with the fly weight, ensuring smooth rotation and normal operation even under high oil pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the decompressor pin operating shaft is disposed in an oil passage to enable smooth operation in normal environments, then the decompression operation is smooth under normal temperature conditions, but the axial movement of the operating shaft is restricted by high oil pressure at very low temperatures, causing motion locking
Solution Approach 1:
The decompressor mechanism is segmented into distinct functional zones: the flyweight rotation zone, the operating shaft axial movement zone, and the pin vertical movement zone. By separating these functions spatially and providing dedicated clearance zones, the patent ensures that high oil pressure in one zone does not interfere with the operation in other zones, particularly preventing the operating shaft from being pushed axially by high oil pressure
Solution Approach 2:
A restricted movement zone is introduced as an intermediary space between the flyweight and the decompressor pin operating shaft. This intermediate zone acts as a buffer that prevents direct transmission of high oil pressure forces from the oil passage to the operating shaft, thereby maintaining smooth operation even under high oil pressure conditions at very low temperatures
2Speed
If the flyweight is journaled at its rim with a small return spring biasing force to enable normal operation at low rotation speeds, then the flyweight can rotate smoothly at low speeds, but the operating shaft is strongly pushed against the flyweight center by high oil pressure, locking the flyweight motion
Solution Approach 1:
The patent segments the force transmission path by creating a restricted movement zone between the flyweight and operating shaft. This segmentation prevents the direct transmission of high oil pressure forces to the flyweight center, allowing the rim-journalled flyweight to rotate freely even when the operating shaft is subjected to high axial forces from oil pressure
Solution Approach 2:
The restricted movement zone serves as an intermediary barrier that decouples the high oil pressure environment from the flyweight rotation mechanism. This intermediate zone absorbs and isolates the axial pushing forces, preventing them from locking the flyweight motion while allowing the return spring to effectively bias the flyweight at low rotation speeds
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
The solution allows for reliable and friction-reduced operation of the decompressor mechanism at high oil pressures, preventing motion locking and ensuring consistent decompression performance across varying temperature conditions.
Implementation Method 1
reliable and friction-reduced operation of the decompressor mechanism at high oil pressures
Data Source
AI summary
An engine decompressor includes a decompressor pin provided through a pin hole on the surface of a valve cam, a decompressor pin operating shaft in an oil passage provided in a valve cam shaft of the valve cam for vertically moving the decompressor pin by its rotation, a fly weight rotatable by rotation of the valve cam shaft so as to rotate the decompressor pin operating shaft, and a thrust receiving plate separate from the fly weight for restricting the axial movement of the decompressor pin operating shaft in the oil passage. The engine decompressor is capable of operating a decompressor mechanism normally even if the lubricating oil increases in pressure.