Low temperatures pose a significant challenge to the fuel atomization performance of butterfly valve carburetors, especially during the start-up phase. The significantly reduced volatility of fuel leads to decreased atomization quality, making mixture formation difficult and consequently affecting engine starting performance and stability. To optimize this, a comprehensive approach is needed, encompassing carburetor structural design, fuel supply system adjustments, and optimization of auxiliary functions, to improve fuel atomization under low-temperature conditions.
The core structure of a butterfly valve carburetor includes the butterfly valve, throttle, injector, and mixing chamber. Its working principle relies on the negative pressure generated by airflow through the throttle to draw in and atomize fuel. At low temperatures, fuel viscosity increases, and its flowability decreases, making it difficult to fully draw in and atomize fuel at the injector, resulting in droplets rather than a uniform mist. These droplets, once inside the cylinder, are difficult to mix thoroughly with air, leading to an overly rich or locally lean mixture, causing starting difficulties, engine vibration, or even stalling. Therefore, the primary task in optimizing low-temperature atomization is to improve fuel flowability and atomization capability at the injector.
To address fuel flow issues, optimization can be achieved by adjusting the geometry and size of the fuel injector. For example, using a finer nozzle design or increasing the number of nozzles can increase fuel injection pressure and enhance atomization. Simultaneously, optimizing the throat structure, by adjusting the length-to-diameter ratio, can alter airflow velocity and negative pressure distribution, allowing the fuel to be more thoroughly torn and atomized in higher-velocity air. Furthermore, adding deflectors or turbulence structures inside the mixing chamber can extend the fuel-air mixing time, promoting further refinement and uniform distribution of fuel droplets.
Adjusting the fuel supply system is also crucial. In low-temperature environments, the fuel pump's supply pressure may decrease due to increased fuel viscosity, leading to insufficient fuel injection. Therefore, it is necessary to appropriately increase the fuel pump's operating pressure to ensure stable fuel flow at the injectors. Simultaneously, the cleanliness of the fuel filter directly affects fuel purity; a clogged filter obstructs fuel flow, further exacerbating poor atomization.
Therefore, regularly replacing the fuel filter and ensuring unobstructed fuel lines are essential measures for maintaining effective atomization at low temperatures. Optimizing auxiliary functions can significantly improve low-temperature start-up performance. For example, introducing a preheating system, by heating the fuel or intake air, can reduce fuel viscosity and increase its volatility, thereby improving atomization. The preheating system can use electric heating wires or heat exchangers to preheat the fuel or air before starting, bringing it to near room temperature. Furthermore, using an electronic control unit (ECU) to intelligently control the butterfly valve carburetor can automatically adjust the fuel injection quantity and butterfly valve opening according to the ambient temperature, achieving a precise air-fuel mixture ratio and avoiding problems of overly rich or lean mixtures caused by low temperatures.
Improving material selection and surface treatment processes is equally important. In low-temperature environments, the mechanical properties and chemical stability of carburetor components may change, leading to decreased sealing or accelerated wear. Therefore, it is necessary to select low-temperature resistant and wear-resistant materials to manufacture key carburetor components, such as using stainless steel or polymer composite materials instead of traditional metal materials. Simultaneously, anti-corrosion treatments on component surfaces, such as chrome plating or spraying wear-resistant coatings, can extend their service life and ensure stable operation in low-temperature environments.
Optimizing the fuel atomization effect of a butterfly valve carburetor during low-temperature starts requires a comprehensive approach encompassing structural design, fuel supply, auxiliary functions, and material selection. Through meticulous adjustments and technological innovation, its starting performance and stability under low-temperature conditions can be significantly improved, providing strong assurance for reliable engine operation in extreme environments.
