Hydraulic Speed Governor With Rigid Feedback Mechanism

Its structure is basically the same as the above-mentioned non-feedback hydraulic governor, except that the upper end A of the lever AC is not mounted on a fixed hinge, but is connected to the piston rod of the servo piston. This change causes the relationship between the sensing element, the hydraulic amplifier element and the oil quantity adjustment mechanism to change as follows.
When the load decreases, the engine speed increases, and the fly ball opens outward to drive the speed rod to move to the right. At this time, the servo piston has not yet moved, so the upper end point A of the feedback lever AC is temporarily used as a fixed point. The lever AC rotates counterclockwise around A, driving the slide valve to move to the right, opening the control hole, and the high-pressure oil enters the right chamber of the power cylinder, and the left chamber is connected to the low-pressure oil circuit. In this way, the high-pressure oil pushes the servo piston to drive the injection adjustment rod to move to the left, and reduces the fuel supply according to the new load.
While the servo piston moves to the left, the lever AC swings to the left around point C, and the slide valve connected to point B also moves to the left, causing the slide valve to move in the opposite direction. In this way, the lever device that can produce an opposite effect on the slide valve movement when the servo piston moves is called a rigid feedback system. When the adjustment process is over, the slide valve returns to the starting position, closes the control oil hole, and cuts off the oil path to the servo cylinder. At this time, the servo piston stops moving, and the injection pump adjustment rod moves to a new equilibrium position, and the engine works under the corresponding new load. Therefore, the governor has different stable speeds corresponding to different engine loads. Because the oil supply needs to be changed when the engine load changes, the position of point A changes with the load. Point B connected to the slide valve should be in its original position under any stable working condition, regardless of the load. In this way, the position of point C must be changed accordingly with point A, which leads to a change in speed. If the load is reduced, after the speed adjustment process is over, when the slide valve returns to the original middle position, the servo piston is in a position with reduced oil supply, causing point A to deviate to the left and point C to deviate to the right. Because point C deviates to the right, the spring is further compressed, and only when it runs at a slightly higher speed can the centrifugal force of the fly ball be balanced with the spring pressure. This shows that after stable operation when the load is reduced, the speed of the diesel engine is slightly higher than before. Similarly, when the load increases, after stable operation, the speed of the diesel engine is slightly lower than before. The hydraulic speed governor with rigid feedback can ensure that the speed regulation process has stable working characteristics, but after the load changes, the diesel engine speed changes, and the stable speed regulation rate d cannot be zero.
If the speed regulation process is required to be stable when the load changes, and the engine speed can be kept constant (that is, it is necessary to use another hydraulic governor with an elastic feedback system.