Carburetor Electronic Control Unit Casing Venting and Integration
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Solution Overview
Problem
Conventional electronic control systems for carburetors are hindered by the separate casing of transmission devices, electric actuators, and electronic control units, leading to inefficiencies in downsizing and increased vulnerability to external factors, particularly in general-purpose engines used with work machines.
Innovation Solution
The integration of a transmission device, electric actuator, and electronic control unit within a common casing, with a ventilation system that includes an air passage and labyrinth structure to prevent pressure buildup and condensation, while ensuring efficient use of space and protection from external elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission device and electric actuator are mounted separately from electronic control unit with individual casings, then protection from external factors is improved, but device size increases
Solution Approach 1:
The patent combines the transmission device, electric actuator, and electronic control unit into a single integrated casing, eliminating the need for separate casings for each component. This merging approach reduces the overall device volume while maintaining protection through the unified casing structure that includes ventilation openings for pressure equalization.
2Volume of moving object
If transmission device and electric actuator are housed in common casing with electronic control unit, then device size is reduced, but protection from external factors deteriorates
Solution Approach 1:
The casing is designed with differentiated local properties: the main body provides sealed protection for internal components, while specific localized openings (ventilation holes) are strategically positioned to allow pressure equalization. The electronic control unit is further protected by being sandwiched between the cover and casing main body, creating layered protection with varying degrees of sealing and ventilation in different zones.
Solution Approach 2:
The ventilation holes act as intermediaries that mediate between the sealed internal environment and the external atmosphere. They allow pressure equalization to prevent condensation and excessive pressure buildup while the casing structure itself serves as the primary protective barrier, thus maintaining protection while enabling necessary environmental interaction.
3Reliability
If ventilation openings are added to casing, then pressure buildup is prevented, but rainwater ingress risk increases
Solution Approach 1:
The ventilation holes are positioned and oriented to exploit gravity and pressure differential in reverse of typical drainage approaches. By placing openings at strategic locations where pressure equalization is needed and orienting them to face away from rain direction, the design allows pressure management while minimizing water ingress risk through inverted thinking about opening placement and orientation.
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 configuration allows for the downsizing of the engine and carburetor system, enhances durability by preventing excessive pressure and condensation, and effectively manages heat dissipation and rainwater ingress, thereby improving the overall reliability and compactness of the electronic control system.
Implementation Method 1
a gap is provided between opposed surfaces of the cover and the electronic control unit so that the gap communicates with the atmosphere through the ventilation means
Implementation Method 2
the ventilation means comprises an air passage extending in the shape of a hook from the gap and opening to the atmosphere with its outer end facing downward
Implementation Method 3
at least a part of the ventilation means comprises a labyrinth which is formed on opposed surfaces of the carburetor and an adjacent member joined thereto and which is opened to the atmosphere with its outer end facing downward
Data Source
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AI summary
An electronic control system for a carburetor, includes: a transmission device (24, 25) linked to a valve (7, 8); an electric actuator (20, 21) for driving the valve (7, 8); and an electronic control unit (12a) for controlling operation of the electric actuator (20, 21). The transmission device (24, 25), the electric actuator (20, 21) and the electronic control unit (12a) are housed and held in a casing (10) mounted on the carburetor (C).. The ventilation means (72, 74, 74', 89, 90) for causing an interior of the casing (10) to communicate with the outside is connected to the casing (10). Therefore, it is possible to house the transmission device, the electric actuator and the electronic control unit efficiently in a common casing so as to downsize the electronic control system for a carburetor, and improve durability of the electronic control unit and the electric actuator.