What is Fuel Controller

Automatic device that controls the amount of fuel delivered to the engine according to flight conditions or pilot instructions to ensure the engine’s operating state, also called fuel regulator. Includes speed controller, air pressure controller and turbo expansion rate controller. Fuel controllers can generally be divided into three types: mechanical-hydraulic, electronic analog and electronic digital.

①Mechanical-hydraulic type: uses high pressure fuel oil as working medium, composed of hydraulic components, cams, levers, etc. For example, the speed controller is driven by the motor rotor to rotate the sensitive element (centrifugal flyweight) to detect the speed change.

When external interference causes the rotation speed to change, the balance between the centrifugal force of the flying weight and the spring force is broken, and the guide rod moves through the lever to make the amplifying element (butterfly valve) move. in the opposite direction, then one end of the actuator (next piston) is injected. The oil discharge piston at the other end moves, causing the piston pump swash plate to rotate, changing the piston stroke, so that the piston fuel supply changes, until the speed returns to the given value and the flyweight’s centrifugal force and spring force are rebalanced. If the driver manipulates the throttle and changes the spring force, this will also cause the controller to move to achieve the goal of changing speed.

Usually, a feedback device is also installed in the controller to improve the dynamic performance of the system. If a gear pump is used for fuel supply, the metering valve can be actuated by the follower piston to change the fuel supply.

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②Electronic analog type: uses electronic components. For example, the speed controller uses an electromagnetic velocity sensitive element to replace the centrifugal flying weight, a transistor amplifier or magnetic amplifier to replace the throttle valve, and an electromagnetic valve or stepper motor to replace the follower piston, which becomes an analogue electronic controller, which is controlled by electrical signals. Because of its low reliability, it has not been widely used.

③ Digital electronic: The fuel system of modern aircraft engines uses digital computers for engine control. This device consists of a microprocessor and input and output interfaces. The electrical signal from the sensitive element is converted into digital information at the input interface and then entered into the microprocessor.

According to the selected control law and operating instructions, the microprocessor obtains the digital information of the output parameters through calculation and converts it into an electrical signal to operate the metering valve through the output interface, which is used to maintain or change the fuel supply to bring the engine running state to meet requirements. The signal of this system is easy to synthesize, it is suitable for multivariable control, it has good versatility, it can shorten the design cycle, it has small inertia, fast response, and high control accuracy.

In addition, the unmanned aircraft is also equipped with electronic remote control or program-controlled fuel controller.

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