Carburetor Variable Air Passage for Engine Load Response
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Solution Overview
Problem
Existing carburetors face challenges in efficiently adjusting the air-fuel ratio based on engine load due to time delays and structural limitations, particularly with mechanical arrangements that require precise control and increased throttle shaft diameters, which affect engine output and freedom in configuration.
Innovation Solution
A carburetor design featuring a throttle body with a variable communication unit and switch mechanism that adjusts the air flow rate by moving a variable communication unit between open and closed positions based on engine load, minimizing response delay and allowing for a high level of freedom in layout design, using a simple structure with a second air passage for independent air supply to maintain atomization and reduce manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cutaway is formed in the throttle shaft to narrow the second air passage, then the air fuel ratio can be reduced when throttle opening is great, but the diameter of the throttle shaft must be increased which reduces the cross sectional area of the throttle valve and adversely affects engine output property
Solution Approach 1:
The invention divides the air supply system into two separate air passages (first air passage 14 and second air passage 15) instead of using a single passage with a cutaway. This segmentation allows independent control of air flow paths, eliminating the need to increase throttle shaft diameter while maintaining air fuel ratio control capability.
Solution Approach 2:
The invention extracts the air fuel ratio control function from the throttle shaft by providing a dedicated first air passage with a variable communication unit (air passage shaft 21) that can be independently actuated. This separates the control mechanism from the throttle shaft, avoiding the need to increase its diameter.
2Manufacturing precision
If the length of the flow passage from the inlet of the second air passage to the air bleed chamber is great, then the cross sectional area of the second air passage can be adequate, but a significant time delay occurs from the time the second air passage is narrowed until the air fuel ratio is actually changed
Solution Approach 1:
The variable communication unit (air passage shaft 21) is positioned upstream in the first air passage to close off the passage before the throttle valve closes. This preliminary action prevents air from entering the long flow passage in the first place, eliminating the time delay that would occur if the passage were closed downstream after air had already entered.
3Area of stationary object
If the diameter of the throttle shaft is increased to ensure adequate cross sectional area for the second air passage, then the second air passage can be adequately sized, but the cross sectional area of the throttle valve is reduced which adversely affects engine output property
Solution Approach 1:
The air supply system is segmented into two independent passages, allowing the second air passage to be adequately sized without requiring an increased throttle shaft diameter. The throttle shaft maintains its original dimensions, preserving the throttle valve's cross sectional area and engine output property.
4Ease of manufacture
If a mechanical arrangement with solenoid valve is used to control fuel jet, then cost is substantially less than electronically controlled fuel injection system, but the flow rate of fuel must be controlled at high precision which is highly difficult to achieve
Solution Approach 1:
The invention replaces the solenoid valve-based mechanical control system with a purely mechanical arrangement using a variable communication unit (air passage shaft 21) that is directly actuated by the throttle valve opening through a link mechanism. This eliminates the need for high-precision fuel flow control while maintaining cost-effectiveness.
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 design effectively adjusts the air-fuel ratio in response to engine load changes with minimal delay, maintaining engine output and allowing for flexible configuration, while reducing the need for precise manufacturing and minimizing costs by using a simple mechanical structure.
Implementation Method 1
a venturi (4) consisting of a narrowed section of the intake passage (3)
Implementation Method 2
The carburetor (1) further includes a float chamber case (12) internally defining a float chamber (11) in a lower part of the throttle body (2) corresponding to the venturi (4)
Data Source
AI summary
In an automotive carburetor, the time delay in the response of the engine to the change in the cross sectional area of the air passage is minimized, and a high level of freedom in selecting the communication cross section area of the air passage and the air fuel ratio for the given load of the engine. The carburetor (1) comprises a fuel passage (13) including a fuel nozzle (16) for supplying fuel to the intake passage, a first air passage (14) communicating with the fuel passage to supply air to the fuel passage, a variable communication unit (21, 41) provided in a part of the first air passage and moveable between an open position for communicating the first air passage and a closed position for shutting off the first air passage and a switch mechanism (22, 43) for moving the variable communication unit between the open position and the closed position in dependence on a load of the engine.