Diesel engines and gasoline engines share a similar overall structure, including components such as cylinder blocks, cylinder heads, pistons, valves, crankshafts, camshafts, and flywheels. However, the key difference lies in their ignition methods: diesel engines use compression-ignition, while gasoline engines rely on spark plug ignition. In a gasoline engine, fuel is mixed with air during the intake stroke and then ignited by a spark plug. In contrast, diesel engines inject fuel directly into the cylinder near the end of the compression stroke, where it is compressed and ignited by the high temperature of the compressed air. This fundamental difference has led to unique structural features in the fuel supply systems of diesel engines.
The fuel injection system in a diesel engine typically includes a fuel pump, an injector, high-pressure fuel lines, and various auxiliary components. The basic process involves the fuel pump delivering diesel through a filter, then sending it to the injection pump. To maintain sufficient pressure, the fuel pump delivers more than what is needed, with the excess returning to the tank via a low-pressure line. The remaining fuel is pressurized by the injection pump and sent through the high-pressure fuel lines to the injectors, which spray it directly into the combustion chamber. A schematic diagram illustrates this system, with line 4 representing the high-pressure pipe and lines 1, 2, and 3 indicating the low-pressure lines, while 5, 6, 7, and 8 represent the return lines.
Modern diesel engines often utilize advanced technologies such as electronic control, common rail systems, and turbocharging with intercooling. These innovations have significantly improved performance in terms of weight, noise, and emissions, making diesel engines comparable to gasoline engines in many aspects and even more environmentally friendly. Many foreign passenger vehicles and agricultural tractors now use diesel engines.
One major distinction between electronically controlled diesel and gasoline engines is that gasoline systems primarily manage the air-fuel ratio, whereas diesel systems regulate fuel injection timing and quantity based on engine speed and throttle position. The ECU calculates the base fuel amount using data from sensors like the speed sensor and throttle position sensor, then adjusts it based on inputs from other sensors such as water temperature, intake air temperature, and intake pressure. This ensures optimal fuel delivery for efficient engine operation.
Electronic control systems in diesel engines consist of sensors, ECUs (computers), and actuators. They enable real-time control of fuel injection quantity and timing based on operating conditions. Sensors provide real-time data to the computer, which compares it with stored values and adjusts the fuel injection pump, EGR valve, and glow plug accordingly. These systems can be categorized into accumulator-type, hydraulic booster-type, and high-pressure common rail systems. The latter is widely used due to its precision and efficiency.
Common rail technology addresses issues caused by pressure fluctuations in high-pressure fuel lines. By maintaining stable pressure in the common rail, it reduces secondary injections, which can lead to increased emissions and fuel consumption. It also improves fuel distribution across cylinders, reducing engine vibration and improving performance. The high-pressure common rail system offers several advantages, including adjustable injection pressure, flexible timing control, and precise injection rate management, allowing for pre-injection and multi-injection strategies that enhance both power and economy.
The system comprises an ECU, a high-pressure oil pump, a common rail (pressure accumulator), electronically controlled injectors, and various sensors. The high-pressure pump supplies fuel to the common rail, which acts as a pressure reservoir. The ECU regulates the rail pressure based on sensor feedback, ensuring consistent fuel delivery. Fuel is then directed to each injector through high-pressure lines, with the ECU controlling the timing and duration of each injection.
High-pressure oil pumps are designed to meet the demands of fuel injection and control oil requirements under all conditions. Modern designs reduce peak torque and noise, improving reliability and efficiency. The common rail itself is carefully engineered to minimize pressure fluctuations while maintaining a quick response to engine changes. Injectors play a critical role, with their design influencing injection timing, rate, and atomization quality.
High-pressure fuel lines must be robust and designed to minimize pressure loss, ensuring consistent fuel delivery to each cylinder. Their length and diameter are optimized to maintain uniform pressure and reduce deviations between cylinders. Overall, the high-pressure common rail system represents a significant advancement in diesel engine technology, offering superior performance, efficiency, and environmental benefits.
Fatten Strong
Fatten Strong,Chemicals And Feed Additives,Cattle Feed Additives,Poultry Feed Powder Mixing
CANGZHOU HUAYOU IMPORT & EXPORT TRADE CO., LTD. , https://www.huayoutrade.com