Operating Principle of Cummins Generator Governor
Working principle of Cummins generator PTG two-pole governor / speed regulator
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.
Working principle of Cummins Generator MVS Governor
On Cummins generator set diesel engine, the PT pump of its PT fuel system is equipped with an MVS full-speed governor in addition to the PTG two-pole governor. It can make the diesel engine run stably at any speed selected by the user to meet the needs of the construction machinery.
The structure of the MVS governor is shown in the figure below. The left side of the plunger is subjected to the pressure from the fuel transfer pump and through the fuel filter diesel oil. The oil pressure changes with the change of the diesel engine speed. The right side of the plunger is in contact with the governor spring plunger to withstand the spring force of the speed governing spring (including the idle speed spring and the governor spring).
When the speed regulating handle of PT pump is in a certain position, the double arm lever under it makes MVS balance the elastic force of spring with the oil pressure on the left side of plunger, so that the diesel engine can work stably at this speed. When the load of the diesel engine is reduced and the rotation speed is increased, the oil pressure on the left side of the plunger is increased, so the plunger is moved to the right, the diesel channel from the throttle valve is reduced, and the output oil pressure of the PT pump drops, and the circulating fuel injection pump amount of the fuel injection pump is also decreased accordingly to limit the increase of the diesel engine speed; On the contrary, when the load of the diesel engine increases and the rotation speed decreases, the spring force of the speed regulating spring is greater than the oil pressure on the left side of the plunger, the plunger moves to the left, and the diesel channel from the throttle valve is opened to make the output oil pressure of the PT pump rises, the circulating fuel injection amount of the fuel injection pump also increases to limit the decrease in the diesel engine speed. By changing the position of the speed regulating handle, the pre-tightening force of the speed regulating spring is changed, and the diesel engine runs stably at another speed. At idle speed, the speed-regulating spring is in a free state and does not work, and only the idle speed spring maintains stable operation at idle speed. The MVS governor is equipped with high speed and low speed limit screws to limit the extreme position of the speed regulating handle.
After the PT pump is attached with MVS governor, the throttle valve is fixed by screws during normal operation. If adjustment is required, the throttle valve is turned to change the oil pressure flowing through the throttle valve to the MVS governor, so that the amount of circulating fuel injection is changed.
The above working principle of Cummins generator governor shared by Jiangsu Starlight Power Equipments Co., Ltd., as an OEM manufacturer of Cummins generator, Starlight can provide customers with 20kw to 2500KW Cummins diesel generator sets. Contact us: sales@dieselgeneratortech.com.
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