Why does the diesel generator set have a "carriage" phenomenon?

Why does the diesel generator set have a "carriage" phenomenon?

The so-called "carriage" refers to the phenomenon that the diesel generator set has a long period and a relatively regular time in the range of low speed and medium speed. This is the result that the speed regulation reaction is excessively delayed from the actual speed. The reasons are mainly the following.

1. The internal lever of the governor is loose due to the wear of the connecting pin hole

In this case, the two-way speed regulation movement of increasing or decreasing the fuel supply amount causes excessive yaw lag. When the engine is working, the speed regulation reaction is necessarily lagging behind the actual speed change, but the hysteresis cannot be too large, otherwise a large adjustment amplitude will be generated. The adjustment amplitude is too large, that is, when the speed has been increased or decreased due to the increase or decrease of the fuel supply, the fuel will continue to increase or decrease. Until the speed exceeds the governor's adjustment range, the strong feedback signal passes through the governor. The reaction of reverse regulation is realized, and as a result, the speed regulation reaction exceeds the predetermined range, causing the phenomenon of "carriage" in which the rotation speed repeatedly rises and falls regularly around a certain value.

2. The oil supply rack is not flexible enough

The fuel supply rod of the fuel injection pump must be absolutely flexible to ensure the sensitivity of the speed regulation reaction. Pulling the resistance test of the toothed rod with a sensitive spring scale, the pulling resistance of the injection pump corresponding to II, IV, VI and VIII cylinders should be no more than 60, 90, 130, 150g respectively. Due to rust, deformation of the plunger member after fastening, crushing of the ring gear and the toothed rod after the plunger spring is broken, severe wear of the end sleeve of the rack end, and the angle of the fork fastening of the fork type oil amount adjusting mechanism Incorrect, the installation or poor fit of the thrust swash plate and the fly ball seat of the domestic fuel injection pump governor will affect the flexibility of the fuel supply rod. When the resistance to the influence of flexibility has not reached the extent that the fuel supply rod is completely unable to move, a "carriage" phenomenon occurs.

3. Steady speed spring adjustment is improper

This is similar to the improper adjustment of the steady speed spring when the idle speed is unstable. This situation is expressed as "carriage" because the steady speed spring and the oil supply rack cannot function together flexibly.