New High Quality Diesel Nozzle DLLA154PN186 for Injection Nozzle Diesel Engine Parts 105017-1860

Core function: Accurately control the fuel injection state
1. Fuel atomization and mixing
Principle: When high-pressure fuel (usually 100~200MPa) passes through the tiny nozzle inside the nozzle, it is broken into oil mist with a diameter of 10~50 microns (similar to the spray effect) due to the intense friction and pressure drop caused by high-speed flow.
Significance: The surface area of ​​the atomized fuel is greatly increased, and the contact with the air is more complete, the combustion speed is accelerated, and the unburned carbon particles (black smoke) and incomplete combustion products (such as CO, HC) are reduced, which increases power and reduces emissions.
Example: In the diesel engine electronic control common rail system, the nozzle nozzle diameter is only 0.1~0.3mm, and the oil mist can be evenly mixed with the air within 0.1 second after high-pressure injection.
2. Injection direction and cone angle control
Design: The number, angle and distribution of the nozzle nozzle holes are customized according to the shape of the combustion chamber (such as the ω-type and bowl-type combustion chambers of diesel engines).
Function: Ensure that the oil mist covers the entire combustion space and prevents the fuel from being sprayed onto the cylinder wall or the top of the piston (causing carbon deposits or oil dilution).
Typical case: The fuel nozzle of a direct injection gasoline engine mostly adopts a 6~8 hole design with a spray cone angle of 60°~90°, so that the oil mist is concentrated near the spark plug to achieve stratified combustion.
3. Fuel cut-off and sealing function
Fuel cut-off simplicity: When the injector solenoid valve is closed or the mechanical plunger is reset, the needle valve inside the nozzle quickly seats, cutting off the fuel supply to prevent dripping (dripping will cause unstable idle speed and increased carbon deposits).
Sealing requirements: The sealing surface of the needle valve and the valve seat is precisely ground (surface roughness Ra≤0.2μm) to ensure no fuel leakage under high pressure and avoid starting difficulties or abnormal combustion (such as pre-ignition).

Subdivision function: Adapt to different engine working conditions
1. Working condition matching and fuel quantity control
Injection characteristics under different loads:
Idle/low load: The nozzle injects a small amount of fuel at a relatively low pressure (such as 50~80MPa for diesel engines), and the spray hole is designed to be fine mist to ensure smooth combustion;
Full load: The pressure is increased to 120~200MPa, the number or diameter of the spray holes is increased, and the penetration of the oil mist is enhanced to meet the demand for large oil volume.
Example: The fuel injection volume of the fuel nozzle of a passenger car diesel engine at full load can reach more than 10 times that at idle, and is precisely controlled by the flow characteristics of the spray holes.
2. Multi-stage injection strategy support
Electronic control injector: Modern fuel nozzles can realize multi-stage injection such as pre-injection, main injection, and post-injection (such as common rail system):
Pre-injection: A small amount of fuel is injected before the main injection to reduce combustion noise and nitrogen oxides (NOx);
Post-injection: Fuel is added in the later stage of combustion to increase the temperature of the after-treatment system (such as DPF) and promote the combustion of particulate matter.
Structural support: The solenoid valve or hydraulic servo system inside the nozzle needs to cooperate with the needle valve to open and close quickly (response time < 0.1ms) to achieve millisecond-level segmented injection.
3. Anti-pollution and self-cleaning design
Anti-clogging function: The nozzle surface is usually chrome-plated or made of wear-resistant materials (such as silicon nitride) to reduce the deposition of fuel impurities (such as sulfur and colloid); some nozzles are designed as inverted cone-shaped nozzles (large inlet and small outlet) to flush impurities with fuel flow.
Self-cleaning mechanism: During high-pressure injection, the flushing effect of fuel on the nozzle can remove slight carbon deposits, but if inferior fuel is used, it may still be blocked (such as a nozzle with a hole diameter of 0.2mm being blocked by 10μm impurities).

Correlation between key structures and functions
Core components of the nozzle Structural features Functional realization
Needle valve and valve seat Conical surface matching (cone angle 3°~6°), surface hardness HRC60+, ground and polished to mirror surface Accurately control the start and end of fuel injection to ensure sealing performance and prevent dripping
Spray hole (single hole/multi-hole) Hole diameter 0.05~0.5mm, number of holes 1~12, hole straightness error < 0.01mm Determine the injection cone angle, oil mist particle size and penetration distance, and adapt to the shape of the combustion chamber
Pressure chamber (volumetric nozzle) Small volume space (0.1~1μL) under the needle valve, storing high-pressure fuel and buffering pressure fluctuations Stabilize the pressure at the beginning of injection to avoid unstable injection at the beginning of oil mist
Solenoid valve/hydraulic control component Solenoid coil response time < 0.5ms, hydraulic servo valve controls needle valve lift (0.1~0.5mm) Precise control of injection timing, injection amount and multi-stage injection in electronically controlled nozzles

Failure impact and functional importance confirmed
Nozzle blockage/wear: The narrowing of the nozzle hole leads to coarse oil mist particles, incomplete combustion, engine power reduction of 10%~20%, fuel consumption increase of 5%~10%, and excessive emissions (black smoke, NOx increase).
Needle valve seal failure: Fuel dripping can cause idle jitter and difficulty in starting. In severe cases, it can cause carbon deposits in the cylinder and even piston top ablation.
Injection angle deviation: The oil mist cannot be evenly distributed, which may cause local high temperature (knock) or low temperature (unburned fuel flushes the cylinder wall), aggravating engine wear.