Carburetor Choke Valve Limiting Rod Mechanism
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Solution Overview
Problem
Carburetor choke valves face challenges in smooth engine startup due to rapid opening caused by high rotational speed and force after engine startup, leading to low mixed gas concentration and hunting phenomena, and manual control is inconvenient.
Innovation Solution
An automatic control apparatus comprising a temperature control assembly, pull-rod, throttle control lever, and choke block, where the temperature control assembly on the cylinder head uses a rotating shaft and coil spring to control the extent of choke valve opening through position-limiting rods, ensuring the choke valve is not fully opened during cold starts and not fully closed during warm starts, regulating gas concentration and air supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the choke valve is fully opened by the forced air after engine startup, then the choke valve opens rapidly, but the mixed gas concentration becomes too low causing hunting phenomenon
Solution Approach 1:
The patent applies preliminary action by pre-positioning the choke valve at a partially open state using a limiting rod before the engine startup process completes. The choke valve shaft is restricted from reaching the fully open position by a limiting rod that blocks rotation at a predetermined angle, ensuring the choke valve maintains an optimal opening degree (not fully open) during the critical startup phase. This preliminary positioning prevents the harmful effect of rapid full opening while still allowing sufficient air intake for reliable engine startup.
2Quantity of substance
If the choke valve is fully closed during manual startup, then the mixed gas concentration is high, but starting the engine becomes difficult
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the choke valve opening degree based on engine temperature conditions. During cold startup, the limiting rod restricts the choke valve shaft rotation to maintain a partially open position, allowing sufficient air intake and achieving optimal mixed gas concentration for reliable ignition. The system changes the operational parameter (choke valve opening degree) from the traditional fully closed position to a controlled partially open position, resolving the contradiction between needing rich mixed gas and ensuring successful startup.
3Speed
If the choke valve shaft rotates rapidly due to flywheel speed, then the choke valve opens quickly, but the choke block cannot be controlled precisely
Solution Approach 1:
The patent applies preliminary action by pre-establishing a mechanical limit on the choke valve shaft rotation using a limiting rod. Before the rapid rotation caused by flywheel speed can result in uncontrolled full opening, the limiting rod is positioned to block the shaft at a predetermined angle, thereby preliminarily controlling the maximum opening degree. This mechanical constraint ensures that even under rapid rotation conditions, the choke valve cannot exceed the optimal opening position, maintaining control precision despite high-speed operation.
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 solution effectively controls the choke valve opening, enhancing engine startup performance by optimizing gas mixture and preventing excessive fuel supply, thus improving engine smoothness and reducing warm-up time.
Implementation Method 1
the coil spring is rapidly heated and expanded causing the rotating shaft to rotate
Data Source
AI summary
An automatic control apparatus for a carburetor choke valve includes a pull-rod, throttle control lever, choke block, and temperature control assembly which is arranged on a cylinder head through a bracket having a rotating shaft and coil spring. The rotating shaft is connected to the spring and one end of the pull-rod via a rotary arm. The other end of the pull-rod is located at a choke valve shaft. The block and valve shaft are connected to respective ends of the lever. During cold start, the block is opened driving the lever to pull the valve shaft. When rotated through a certain angle the valve shaft is blocked by part of the pull-rod, such that the valve and block cannot be fully opened. During warm start, the valve shaft when returning is blocked by another part of the pull-rod such that the valve cannot fully close.