Cummins m11 Xi'an fuel injector adjustment method

Torque method and lift method are common methods for adjusting fuel injectors. The torque method is to make the injector plunger at the lower end of the working stroke and screw in the adjustment screw to reach a certain torque value, so that the plunger exerts a certain pressure on the conical cover. The lift method is to make the injector plunger at the upper end of its working stroke and screw in or out the adjustment screw to make the downward stroke of the injector plunger meet the specified value during operation, forming a certain pressure on the conical cover. When using the torque method to adjust the injector, the plunger must be located at the lower end of the working stroke; when using the stroke method, the plunger must be located at the upper end of the working stroke. The two must not be confused.

When installing the fuel injector, first clean and wipe the mounting hole, install the three O-rings on the fuel injector, then insert it into the mounting hole, and put the fuel injector pressure plate in place. Use a torque wrench to tighten the two pressure plate fixing screws. The torque must be based on the value specified on the diesel engine nameplate. The NH-220 diesel engine is 17~19N?m, and the NT-855 diesel engine is 14~16N?m. After installation, use the torque method to adjust the injector rocker arm adjustment screw.

(1) Find the correct timing for adjustment: Rotate the tape reel in front of the PT pump transmission gear in the direction of crankshaft rotation (see Figure 2). Its rotation speed is synchronized with the crankshaft, and there are adjustment marks on the tape reel. There are 1-6TC on the tape reel of the NH-220 machine as the top dead center mark, and 1-VS, 2-5VS, and 3-4VS as the adjustment marks of each cylinder. At 90° after the top dead center of the compression stroke of the I cylinder, the 1-6VS mark should be aligned with the mark on the body at this moment.

At this time, the I cylinder is in the middle of the explosive downward movement, and the temperature and pressure in the cylinder are high. At this time, adjust the rocker arm adjustment screw to reach a certain torque, so that the injection plunger and the base have a certain degree of pretension, which can prevent high temperature Gas enters the injector, greatly reducing injector failure.

It can be seen from the cam profile in Figure 3 that the compression stroke of the I cylinder is 90° after the top dead center, and the cam angle is 45°. The corresponding contact point is point F on the large radius of the profile. The plunger is at the lowest position, which is the adjustment plunger. Timing of pressure on the injector base