Aerospace
The hydraulic system is one of the important systems of products in aerospace industry. The control system of the aircraft, such as the horizontal tail, vertical tail, flaps, ailerons, rudder, executive booster, arm changer, human-sensing system, etc., all adopt hydraulic control systems. The constant speed and constant frequency adjustment of the aircraft engine, the tracking of the radar and turret in the firepower system, the steering of the nose landing gear, and the wheel brake system are also controlled by the hydraulic system.
Development Trend of Aviation Hydraulic System
1. Light weight and small size
With the development of aircraft towards high speed and high maneuverability, reducing the weight and volume of the onboard hydraulic system is an inevitable requirement for the development of the next generation of aircraft. From the perspective of the flight performance and reasonable weight distribution of high-performance aircraft in the future, the weight of the most favorable onboard hydraulic system should be less than 1% of the total aircraft weight, while the current onboard hydraulic system accounts for about 3%-15% of the total aircraft weight. Therefore, reducing the weight and volume of the onboard hydraulic system is an inevitable trend in the development of the next generation of aircraft.
2. High pressure
System high pressure, while effectively reducing the weight and volume of the system, will reduce system efficiency, increase system heat generation, make pressure pulsation and pipeline vibration more serious, and increase aircraft maintenance costs. Therefore, the selection of the pressure level of the aircraft hydraulic system should make the overall performance of the aircraft and the system the best.
3. High power
In the future, the power of the hydraulic system of the aircraft will be greatly increased, mainly because the improvement of the performance of the aircraft will increase the number of control and manipulation functions using hydraulic power on the aircraft. Increased aircraft speed and maneuverability lead to greater aerodynamic loads and faster actuation rates on the aircraft's control surfaces, and thus greater power to the hydraulic actuators that drive these surfaces.
4. Variable pressure pump source system
For the existing on-board hydraulic system, the working efficiency of the actuator is relatively higher than that of the pump source of the system, and most of the power loss is generated by the pump source or is closely related to the working form of the pump source. In view of this, the United States, the United Kingdom and other countries are developing variable pressure airborne hydraulic systems, and proposed two types of pump sources for airborne hydraulic systems, two-stage pressure variable pumps and intelligent pumps, to solve the problem of negative impact from high-pressure and high-power airborne hydraulic systems on aircraft in the future.
5. Reducing Ineffective Power Consumption
The aircraft puts forward high pressure and high power requirements for the onboard hydraulic system, but it also brings new problems, the most prominent one is the increase of the calorific value of the hydraulic system. The intelligent pump source system is a system that uses the principle of a load-sensitive pump to control the hydraulic pump with a microcomputer controller. In order to achieve control, it has to install necessary sensors on the hydraulic pump and the system, including pressure sensors, flow sensors, displacement sensors and temperature sensor etc. By sensing the state parameters of the system, the controller controls the displacement of the hydraulic pump according to the pressure and flow instructions, and finally achieves the best match between the pump source and the load.
