The function of the governor is to automatically adjust the fuel supply quantity in accordance with the change of the external load of the diesel engine within the working speed range of the diesel engine to keep the diesel engine speed basically stable. For diesel engines, changing the fuel supply requires only turning the plunger of the fuel injection pump. As the oil supply increases, the power and torque of the diesel engine increase accordingly, and vice versa.
The load of the diesel generator set is constantly changing, which requires that the output power of the diesel engine also changes frequently, and the frequency of the power supply is required to be stable, which requires the rotational speed of the diesel engine to remain stable. Therefore, a speed governing mechanism must be installed on the diesel engine of the diesel generator set. The governor generally consists of two parts: the sensing element and the actuator. According to the different working principle of the governor, it can be divided into mechanical governor, electronic governor and electronic injection governor.
Mechanical governor
The mechanical speed control system works by the flying hammer rotating at the corresponding speed of the diesel engine. The centrifugal force generated by the flying hammer during the rotation can automatically adjust the fuel inlet amount when the generator set speed changes, thereby achieving the purpose of automatically adjusting the unit speed.
Figure 2.3 is a schematic diagram of the centrifugal full speed governor.
1. Governor shaft
2. Flying hammer support
3. Flying hammer pin
4. Flying hammer
5. Slide bushing
6. Pendulum bar/swing rod
7. Swing link pin
8. Governor spring
9. Fuel injection pump rack
10. Operating handle
11. Sector rack
12. Maximum position speed limit screw
13. Minimum position speed limit screw
Move the position of the operating handle to change the tension of the spring, so that the tension and thrust on the swing rod are in a new equilibrium position. At the same time, the position of the fuel pump rack is changed to adjust the diesel engine to the required speed and work automatically and stably at this speed.
Under normal circumstances, the speed of the diesel generator set with mechanical speed regulation system will decrease slightly with the increase of the load, and the automatic variation range of the speed is ±5%. When the unit has a rated load, the unit's rated speed is approximately 1500 rpm.
Electronic governor
The electronic governor is a controller that controls the speed of the engine. Its main functions are: to keep the engine idle speed at a set speed; keep the engine's operating speed at a preset speed without being affected by load changes. The electronic governor is mainly composed of three parts: controller, speed sensor and actuator.
The engine speed sensor is a variable reluctance electromagnet that is mounted above the flywheel gear ring in the flywheel housing. When the gears on the ring gear pass under the electromagnet, an alternating current is induced (one gear produces a cycle).
The electronic controller compares the input signal with the preset value, and then sends the correction signal or the maintenance signal to the actuator; the controller can perform various adjustments to adjust the idle speed, running speed, sensitivity and stability of the controller. starting fuel quantity and engine speed acceleration;
The actuator is an electromagnet that converts the control signals from the controller into control forces. The control signal transmitted by the controller to the actuator is transmitted to the fuel control rack of the fuel injection pump through a connecting rod system.
Electronic injection speed governor
The EFI (Electronic fuel injection) gen set controls the injector operation by adjusting various information of the diesel engine detected by a series of sensors installed on the engine through an electronic control module (ECU) on the diesel engine, adjusting the injection timing and fuel injection quantity to make the diesel engine in the best working condition.
The main advantages of EFI speed regulation: Through the electronic control of injector injection timing, fuel injection quantity and high pressure injection pressure, the mechanical performance of the diesel engine can be optimized; the fuel injection quantity can be precisely controlled by ECU; the fuel consumption of the diesel engine decreases in normal operation, which is more economical and lower in emissions, and conforms to EURO non-highway internal combustion engine emission standards;
Through the data communication line, it can be connected with an external instrument panel and a special diagnostic tool, which makes installation easier, increases the detection point of the fault point, and is more convenient for troubleshooting. The composition of the EFI diesel engine management system is shown in Figure 2.4:
Description: CIU refers to the control interface device, such as the control panel; ECU refers to the electronic control module, which is installed on the diesel engine.
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