The nozzle is used to spray fuel in accordance with the shape and volume of the combustion chamber

Spraying occurs due to the high speed of the expiration of fuel under high pressure, due to friction when moving through the spray holes and collision with a hot vortex of compressed air

KamAZ engines use closed-type nozzles with a shut-off sprayer needle.

In the intervals between fuel injections, the fuel outlet hole is closed with a needle.

The nozzle opens only at the moment of injection, when fuel begins to flow to it from the high pressure pump.

Kamaz car nozzle

The body 6 (Fig. 1) of the nozzle is connected to the atomizer with a nut 2 through a spacer 3.

The multi jet atomizer consists of a needle 14 and a body 1, in which four sawing holes with a diameter of 0.3 mm (model 33), 0.32 mm (model 271) or 0.33 mm (model 272) are drilled.

These holes are located at different angles to the axis, ensuring uniform distribution of fuel throughout the volume of the combustion chamber.

A pair of parts 1 and 14 is precision, the gap between the needle and the atomizer does not exceed 5 microns.

The cone of the needle rests on the cone of the atomizer body, separating its fuel supply channels and atomizing holes.

For a secure seal, the nozzle stop cone is angled at 59° and the needle cone is angled at 60°.

This design of the sealing surfaces of the needle and the atomizer makes it possible to do without their mutual grinding in.

Annular grooves on the needle guide of the atomizer, trapping leaked fuel and distributing it like a lubricant, improve the mobility of the needle.

The spacer with its pins fixes the atomizer relative to the nozzle body in a strictly defined position, and also limits the stroke of the atomizer needle, which is 0.25 mm.

The locking needle is pressed against the nozzle seat through the rod 5 by the spring 13.

The upper end of the spring rests against the adjusting washers 11, 12.

Fuel is supplied to the nozzle through fitting 8.

To filter out process contaminants that can get into the fuel line during assembly, a safety filter 9 is installed between the nozzle and the nozzle body.

Kamaz vehicle injector

After passing the safety filter through the channels: G of the body 6, D of the spacer 3 and E of the body 1, the fuel enters the annular chamber under the cone of the needle 14.

Further along the annular gap between the needle and body 1, the fuel flows to the shut-off cone.

When the pressure in chamber B, acting on the cone of the needle, exceeds the resistance of the spring 13, the needle will rise until its end stops against the spacer 3, while the fuel is injected through the holes of the atomizer body into the combustion chamber of the cylinder.

At the moment when the injection pump section stops supplying fuel, the pressure in the annular chamber B drops sharply, the spring 13 lowers the needle and the injection stops instantly.

The pressure at which fuel injection starts is set with adjusting washers 11 and 12.

No more than three shims are allowed.

When the thickness of the package of shims increases by 0.05 mm, the injection start pressure increases by 30...50 kPa.

Under the action of high pressure, a small part of the fuel seeps between the needle and the sprayer body into the cavity of the spring 13. From here, it is discharged into the tank through the channel and the drain fuel drive.