Working principle of Cummins Generator PTG Governor

by Starlight Generator dieselgeneratortech

1. Idling condition

At idle, the throttle is in the closed position and fuel flows only through the idle throttle to the injector. If the rotation speed is reduced for some reason and the centrifugal force of the flying block is reduced, the idle speed spring pushes the governor plunger to the left to increase the cross section of the orifice leading to the idle oil passage, and the oil supply amount increases. When the speed increases, the PTG governor plunger moves to the right, the flow cross section decreases, and the oil supply decreases, thereby keeping the idle speed stable. The idle adjustment screw is used to change the steady speed of the idle speed.

2. High speed condition

When the speed of the diesel engine increases, the plunger and idle spring of the PTG governor are compressed, which is mainly acted by the high speed spring. The left notch of the plunger groove of the PTG governor has gradually moved to the hole leading to the throttle valve in the middle. When the speed is in the specified speed, the incision is on the left side of the orifice. At this time, if the speed of the diesel engine increases, the plunger will continue to move to the right, and the flow section of the orifice will be reduced, so that the amount of oill flowing to the injector will be reduced. When the load of the diesel engine is completely removed, the cross section of the orifice is very small, and the cross-shaped radial hole at the right end of the plunger has been removed from the governor sleeve to communicate with the adjacent oil passage. The diesel engine operates at the highest idling speed, which limits the increase in speed.

3. High speed torque correction

When the diesel engine works at low speed, the high speed torque correction spring at the right end of the flying block is in a free state. If the engine speed increases, the centrifugal force of the flying block increases, causing the regulator plunger to move to the right. When the rotational speed exceeds the maximum torque rotational speed, the spring begins to be compressed, so that the axial force of the flying block on the governor plunger is reduced, and thus the fuel pressure is also reduced, and the torque is reduced. The higher the speed, the more the torque decreases, which improves the torque adaptability of the diesel engine at high speed.

4. Low speed torque correction

When the diesel engine speed is lower than the maximum torque point speed, the plunger of the PTG governor moves to the left, compresses the low speed torque correction spring, and the governor plunger increases the thrust to the right, so that the fuel pressure increases accordingly, the fuel supply increases, the torque of the diesel engine rises, which slows down the tendency of the torque to be reduced at the low speed of the diesel engine and improves the adaptability of the torque at low speed.

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