Carburetor Assembly Interlock Lever Mechanism for Cold Start
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Solution Overview
Problem
Existing carburetor designs for two-stroke internal combustion engines face challenges in adapting to different engine designs and facilitating cold starting, as they often require the air valve to be closed during cold start-ups, limiting the start gas opening degree of the throttle valve.
Innovation Solution
A carburetor assembly with a pivotable trigger lever connected to the air valve lever and interlock lever, allowing the interlock lever to pivot away from the abutting engagement at an offset angle, enabling the throttle valve to be set in the start gas position without affecting the air valve lever, and incorporating a lost motion coupling for delayed air valve opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the air valve is closed during cold start-up, then the throttle valve can be opened to a larger degree for start gas, but the start gas opening degree is limited by the interconnected lever mechanism
Solution Approach 1:
The lever mechanism is segmented into independent controllable parts: the trigger lever can be independently positioned to set the throttle valve opening degree, while the interlock lever can be independently engaged or disengaged from the choke valve lever. This segmentation allows the throttle valve to be opened to a larger degree during cold start-up without being constrained by the air valve position, as the interlock lever can be disengaged to permit independent throttle valve movement.
2Adaptability or versatility
If the interlock lever is rigidly connected to the throttle valve, then the throttle valve position is controlled, but the start gas position cannot be optimized independently of the air valve position
Solution Approach 1:
The connection between the interlock lever and throttle valve is made dynamic rather than rigid. The interlock lever can be engaged with the choke valve lever to provide a fixed interlocked position, or disengaged to allow independent adjustment of the throttle valve opening degree. This dynamic connection enables optimization of the start gas position independently of the air valve position while maintaining controlled throttle valve operation during normal running conditions.
3Device complexity
If the trigger lever is directly connected to the interlock lever, then the interlock position is set, but the throttle valve opening degree is limited
Solution Approach 1:
The choke valve lever serves as an intermediary element between the interlock lever and the throttle valve control. The interlock lever engages with the choke valve lever to establish the interlocked position, which in turn controls the throttle valve opening degree. This intermediary mechanism allows the trigger lever to be directly connected to the interlock lever for simple positioning, while still achieving a larger throttle valve opening degree through the coordinated action of the choke valve lever during cold start-up.
Data Source
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AI summary
The invention relates to a carburetor assembly (10) for a two-stroke internal combustion engine, the assembly comprising a main intake passage (12) accommodating a throttle valve (30), an additional air passage (14) accommodating an additional air valve (50), a pivotable air valve lever (55) turning together with the air valve (50), and an interlock lever (35) turning together with the throttle valve (30). The interlock lever (35) is configured to be settable in an interlocked pivotal position, in which the throttle valve (30) is open to a certain degree in order to provide a start gas position of the throttle valve (30), wherein the interlock is arranged to be released if the interlock lever (35) is pivoted further in the opening direction of the throttle valve (30). The assembly further comprising a pivotable trigger lever (45) responsive to e.g. pulling of a throttle trigger and being operatively connected to the air valve lever (55). The pivotable trigger lever (45) is operatively connectable to the interlock lever (35) or a member that moves with the interlock lever (35) via an abutting engagement at predetermined relative positions of the trigger lever (45) and the interlock lever (35). Further, the trigger lever (45) is arranged to permit the interlock lever (35) to pivot away from the abutting engagement in the opening direction of the throttle valve (30) at least to an offset angle ( ) relative to the trigger lever (45), such that the interlocked lever (35) can be set in the interlocked position without affecting the pivotal position of the trigger lever (45).