governor (Governor) is an automatic adjusting device, which changes according to the load of the diesel engine, an automatic increase or decrease the amount of oil injection pump, the rotational speed diesel engine can be run in a stable.
1. Governor main categories
According to their works
according to the different works can be divided into mechanical, pneumatic, hydraulic, pneumatic mechanical compound, hydraulic hybrid mechanical and electronic and other forms. But undoubtedly the most widely used mechanical governor, the structure is simple, reliable, good performance.
was added a hydraulic governor hydraulic amplifying element (hydraulic servo) between the inductive element and the fuel adjustment mechanism, so that the output signal of the sensing element by amplifying the fuel adjustment member and then spread up mechanism, thus indirectly also called acting governor.
has an enlarged hydraulic amplifying element and the role performed mainly by the control and execution of two parts.
1, no feedback hydraulic governor
It works as follows:
When the load is reduced, a drive shaft driven by the crankshaft speed increases, the centrifugal force of the fly ball to increase, pushing the speed rod to the right. Thus the governor, the rockerA point in the center is rotated counterclockwise, the spool shifted to the right, the pressure oil into the right space of the servo cylinder. At the same time, the left part of the cylinder space through hole communicating with the low pressure oil passage, wherein the oil is vented. Under the action of differential pressure fuel pump rack drive servo piston to the left, in order to reduce the amount of oil. When the rotational speed returns to the original value, but also the spool to the center position, the adjustment process ends.
When the load increases, the speed is reduced, the process speed in the opposite direction.
From the above analysis shows, the centrifugal force generated by the governor fly ball to merely push the spool, and thus the size of the weight of the ball will fly can be made smaller. As the force of the hydraulic servo amplifier may be required to select different sizes and different oil pressure servo piston to be enlarged.
However, in this governor, since the valve spool directly driven inductive element, regardless of which direction to move it, it is difficult to accurately return to the original position to close the oil hole. This allows the engine speed instability, severe fluctuations.
In order to stably adjust the governor, the governor also added in a device, a function of generating a reaction to the slide valve servo piston while moving, moved in the direction of the equilibrium position, reducing diesel possibility of speed fluctuation. This apparatus is called a feedback mechanism.
2, having a rigid hydraulic governor feedback mechanism
that the above-described non-feedback configuration with the hydraulic governor is substantially the same, only the upper end of the lever-defined AC A governor is not mounted on the fixed hinge, and It is connected with the piston rod of the servo piston. This change allows the sensing element, the relationship between the change in the hydraulic amplification means and the fuel element occurs following adjustment.
When the load is reduced, the engine speed increases, the fly balls outwardly flared speed drive rod is moved to the right. At this time, the operation of the servo piston yet, the feedback lever on the AC terminal A temporarily as a fixed-point, AC A lever is rotated counterclockwise to drive the valve spool is moved rightward, the control hole is opened, high pressure oil will enter the power cylinder about the right chamber, left chamber communicates with the low pressure oil. Such high pressure oil pushes the piston of the servo driven adjusting lever is moved leftward injection, according to the new load and fuel supply amount reduction.
while the left servo piston, the lever pivot point C AC spool around point B is also connected to the left moves to the left, so that the spool in the opposite direction. So that when the servo piston moves to produce the opposite effect on the movement of the slide valve apparatus as rigid lever feedback system. When adjustedAt the end of the process, back to the starting position of the slide valve, the control hole closed, cutting off the oil passage leading to the servo cylinder. In this case the servo piston stops moving, the fuel injection pump adjustment lever will move to a new equilibrium position, the engine operates at the corresponding new load. Thus, corresponding to different engine load, the governor will have different stable speed. Because of the need to change the fuel supply amount when the engine load change, the position of the point A with load variations. Governor and point B is connected to the spool valve at any stable conditions should be in its original position, irrespective of the load. Such a position of point C with point A must change accordingly, resulting in a change in the rotational speed. Provided that when the load is reduced when, after the process speed, the intermediate slide valve back to its original position, the servo piston reduces the amount of oil in the position, the left point A, point C to the right, because the point C to the right, the spring further pressure, and only operate at a slightly higher speed to make the ball fly with the centrifugal force spring pressure balance. This shows that the steady operation when the load is reduced, the rotational speed of the diesel engine is increased slightly than the original. Similarly, when the load increases, the stable operation of the diesel engine speed slightly lower than the original. The hydraulic governor having a rigid feedback speed control process can ensure stable operating characteristics, but the change in load, engine rotation speed changes, a stable transfer rate can not be zero d.
If the required load change that is, to speed the process stability, while maintaining constant engine speed (i.e., the other must be used with a hydraulic transporting resilient feedback system.
3, elastic feedback hydraulic governor
it is in fact quot; rigid feedback quot;. was added a resilient link means – and a buffer connected to the spring end of the spring with a fixed fulcrum, the other end of the buffer piston is connected to the piston of the buffer cylinder with rigid coupling to the server.
when the engine load decreases, speed increases, the centrifugal force of the fly ball increases. Similarly, the right spool valve, and the governor servo piston is left , reduce the amount of oil injection pump when the piston velocity is high, the buffer and the damping piston moving in the same manner as a rigid body. with the left servo, a point on the buffer piston and the lever 5 is also AC moves to the left. this process is identical to said rigid feedback system and the governor, but when the process speed near the end of the slide valve has returned to its original position, the oil passage leading to the servo cylinder cover, in which case buffer And a servo piston is stuck in a position corresponding to the new load. IsSince the compressed spring elastic restoring action, so that the point A damper piston driven cylinder move to the right with respect to the buffer and return to the original position. Buffer throttling valve piston oil flows rightward in the left cylinder. Thus, each point on the AC levers are restored to the original position, this time also because the rotational speed of the governor sleeve and restored to its original position. Thus, the engine speed remains unchanged, when the load increases, the opposite course of action. Stable transfer rate of such a governor is zero d.
2. Governor operation mode
Some machines governor for reducing non-periodic velocity fluctuation of the automatic adjustment means. The basic structure of the whole engine speed governor enables or maintained near the set setpoint value. Turbine, steam turbine, gas turbines and internal combustion engines with different motor, the output torque can not automatically adapt to changes in the load itself, so that when the load changes, the drive unit will lose their stability. Such governor unit must be set so that it can load the like as conditions change, and establishing the relationship between the load and the amount of energy supplied at any time, to ensure that the unit for normal operation. Theory and design issues governor, is to study the mechanical dynamics of the content. Many different types of governor. Wherein the most widely used is a mechanical centrifugal governor. And with tachometer generator or other electronic devices as sensors governor, has been widely used in various industrial sectors.
The governor must satisfy the stability condition:
① When the unit speed deviation and the set value, the governor can make the appropriate response action, while they must have a restoring force acting in the governor often replied from the initial state. Centrifugal governor spring restoring force is zeroPieces. This governor, said the governor static stability. However, the governor statically stable dynamic instabilities may also occur during the adjustment, when adjusting the adjustment operation over the reverse occurs, the actual adjustment operation will form an oscillating process. The oscillation can quickly decay governor, called dynamic stabilization of the governor, or governor is a dynamic instability, which can not guarantee the machine is working properly.
② is a method of increasing the damping of the dynamic stability improved conditioning system. Adjusting the damping in the system, for example high frequency control sub-friction movement, the governor has a certain insensitivity, i.e., when the control shaft speed is slightly deviated from the set value, the governor does not produce a corresponding action. Insensitivity to mechanical governor generally about 1 percentage of its set value. Governor high sensitivity, also due to the periodic speed fluctuation of the normal operation of the unit generating undue adjustment operation.
A governor is used to maintain a stable rotational speed of the diesel engine. During load changes of the diesel engine, which speed is changed accordingly. When the speed is reduced, if the governor is not adjusted, the diesel engine will eventually stopped; when the speed increases, if the governor does not act, the diesel engine will eventually be subjected to excessive centrifugal forces can not be damaged. Effect of the governor is to maintain a stable rotational speed of the diesel engine. In addition, the governor can maintain the minimum speed diesel engines and maximum speed, prevent, and turn off when high-speed operation at low speed operation, “Speed”, resulting in mechanical damage.