MarketsHydraulic system in aviation and river-sea engineering

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     Aviation and river-sea engineering are important fields with a long history of applying hydraulic technology.

     The application of hydraulics in modern military and civilian aircraft is diverse, including the aircraft's own main pressure supply system, fuel supply control system, brake system, etc., as well as ground ancillary facilities.

     The application of hydraulic technology in river and ocean engineering has a history of nearly a hundred years. In addition to the deck machinery of civil and engineering ships and the weaponry of military ships, hydraulic technology is also widely used in modern river crossing equipment, deep submersible lifeboats, underwater robots and other river and ocean operation equipment.

    Picture shows a simplified schematic diagram of an aircraft hydraulic system. The oil source is two parallel variable axial plungers SI, f oil pressure is set by the overflow valve 2; the accumulator 5 is used to absorb hydraulic pulsation and Pressure shock in the oil inlet of the actuator. The system has multiple actuators such as landing gear retractable hydraulic cylinder 7, aileron booster 8, steering gear 9, flat tail booster 10, and steering gear 11. When the traditional system is multi-actuator working, the oil supply is only It is insufficient to cause the actuator working speed to be reduced, the movement time is prolonged, and the oil source pressure is low, so that the output force of the booster is too small to meet the requirements of the control system; pressure surges and high-frequency pressure oscillations appear in the oil return pipeline, which affects Problems such as the service life of pipes and accessories and the normal operation of the system. The landing gear retracted part is the main factor leading to the above-mentioned problems.


    The improved hydraulic system is to add a priority valve 12 (should be island pressure, high flow II: and high-precision pilot relief valve) in the landing gear part of the original system, that is, put it in three-position four-way Before the electromagnetic reversing valve 6, the interference problem of the multi-actuator hydraulic system combined work can be solved, and the system work can be more reasonable. When the landing gear part is retracted and retracted, the solenoid valve 6 is energized so that the pressure oil of the hydraulic pump enters the hydraulic cylinder 7 through the filter 3, the one-way valve 4, the priority valve 12 and the reversing valve 6, and the piston rod drives the landing gear to retract. Or put the function. If the system oil supply pressure is lower than the opening pressure of the priority valve 12, the priority valve 12 automatically closes the oil circuit, cutting off the oil supply from the system to the landing gear part, and guarantees the aileron booster 8, the steering gear 9, and the flat tail booster 10. And the steering gear 11 and other actuators have sufficient energy. When the flight control and other actuator functions are completed, the fuel supply pressure of the system rises, and when the fuel supply pressure is greater than the opening pressure controlled by the priority valve 12, the priority valve connects the oil source and the oil circuit of the landing gear retractable part. The working principle of the priority valve is similar to that of the traditional pilot-operated relief valve. The difference is that the outlet of the valve is not connected to the fuel tank, but to the retractable part of the landing gear actuator, so the leaking oil port must be leaked outside (that is, connected back separately tank).

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