A complete hydraulic system consists of five parts, namely power element, actuator, control element, auxiliary element and working medium.
Components
The function of the power element is to convert the mechanical energy of the prime mover into the pressure energy of the liquid. The power element refers to the hydraulic pump in the hydraulic system, which provides power to the entire hydraulic system. The structural forms of hydraulic pumps generally include gear pumps, vane pumps, plunger pumps, and screw pumps.
The function of the actuator is to convert the pressure energy of the liquid into mechanical energy and drive the load to make linear reciprocating motion or rotary motion. The actuators include hydraulic cylinders and hydraulic motors.
The control element (i.e. various hydraulic valves) controls and regulates the pressure, flow and direction of the liquid in the hydraulic system.
According to different control functions, hydraulic valves can be divided into pressure control valves, flow control valves and directional control valves. Pressure control valves are further divided into overflow valves (safety valves), pressure reducing valves, sequence valves, pressure relays, etc.; flow control valves include throttle valves, regulating valves, flow diversion and collection valves, etc.; directional control valves include check valves, hydraulic control check valves, shuttle valves, reversing valves, etc. According to different control methods, hydraulic valves can be divided into switch control valves, fixed value control valves and proportional control valves.
Auxiliary components include accumulators, filters, coolers, heaters, oil pipes, pipe joints, oil tanks, pressure gauges, flow meters, sealing devices, etc. They play auxiliary roles such as connection, oil storage, filtration and measurement of oil pressure. Please refer to
"Hydraulic Transmission" and "Hydraulic System Design Series".
The working medium refers to the hydraulic oil or emulsion in various types of hydraulic transmission, which includes various mineral oils, emulsions and synthetic hydraulic oils. The hydraulic system realizes motion and power transmission through it.
Hydraulic components
Hydraulic components can be divided into three categories: power components, control components and actuators. Although they are all hydraulic components, their own functions and technical requirements for installation and use are also different. They are introduced as follows:
Power components: refers to various hydraulic pumps, gear pumps, vane pumps, plunger pumps, screw pumps.
1. Two structural types: gear oil pumps and tandem pumps (including external meshing and internal meshing).
2. Vane oil pump (including single-stage pump, variable pump, two-stage pump, duplex pump).
3. Piston oil pump, which is divided into axial piston oil pump and radial piston oil pump. Axial piston pump has fixed displacement pump, variable displacement pump (variable displacement pump is divided into manual variable displacement pump, pressure compensation variable displacement pump, servo variable displacement pump, etc.). Structurally, it is divided into two oil distribution methods: end oil distribution and valve oil distribution. The oil distribution type of radial piston pump is basically valve oil distribution. );
Actuators: hydraulic cylinders and hydraulic motors. Hydraulic cylinders include piston hydraulic cylinders, plunger hydraulic cylinders, swing hydraulic cylinders, and combined hydraulic cylinders; hydraulic motors include gear hydraulic motors, vane hydraulic motors, and plunger hydraulic motors;
Control elements: directional control valves, one-way valves, and reversing valves;
Pressure control valves: overflow valves, pressure reducing valves, sequence valves, pressure relays, etc.;
Flow control valves: throttle valves, speed regulating valves, and diverter valves;
Auxiliary elements: other elements other than the above three parts, including pressure gauges, oil filters, energy storage devices, coolers, pipe fittings {mainly including: various pipe joints (expansion type, welding type, ferrule type, SAE flange), high-pressure ball valves, quick-change joints, hose assemblies, pressure measuring joints, pipe clamps, etc.} and oil tanks, etc., which are also very important.
