I. Main hydraulic circuit
The basic circuit consists of the relevant hydraulic components, used to complete a specific function of the typical oil circuit. Any hydraulic transmission system is composed of several basic circuits, each basic circuit has a certain control function. Several basic circuits can be combined together to control the direction of motion, working pressure and speed of the actuator according to certain requirements. According to different control functions, the basic circuit is divided into pressure control circuit, speed control circuit and direction control circuit.
II, Speed Control Circuit
Speed control circuits are circuits that control the movement speed of the actuator by controlling the flow of the medium. It is divided into speed control circuit and synchronization circuit according to different functions.
(1) synchronous circuit: control two or more than two actuators synchronous operation of the circuit, such as the use of the two actuators rigidly connected to ensure synchronization; throttle valve or speed valve to adjust the flow of the two actuators were equal to ensure synchronization; hydraulic cylinders of the pipeline in series to ensure that the flow into the two cylinders is the same, so as to make the two hydraulic cylinders synchronized.
(2) speed circuit: used to control the movement speed of a single actuator, you can use a throttle valve or speed control valve to control the flow, such as the figure of a simple grinder in the hydraulic transmission system schematic diagram of the throttle valve plays this role. Throttle valve to control the hydraulic pump into the hydraulic cylinder flow (excess flow through the relief valve back to the tank), thereby controlling the speed of movement of the hydraulic cylinder, this form is known as throttle speed control. Can also be used to change the output flow of the hydraulic pump to speed, known as volumetric speed control.
III, direction control circuit
Direction control circuit Control of the hydraulic medium flow direction of the circuit. With a directional control valve to control the direction of movement of a single actuator, so that it can move in the positive and negative direction or stop the circuit, known as the reversing circuit, Figure Simple grinder hydraulic transmission system schematic diagram of the reversing valve that plays this role. When the actuator stops, the circuit that prevents the actuator from moving due to leakage caused by external factors such as load is called a locking circuit.
IV. Pressure control circuit
Pressure control circuits are circuits that use pressure control valves (see Hydraulic Control Valves) to control the pressure of the entire system or a localized range. According to different functions, the pressure control circuit can be divided into regulating pressure, variable pressure, unloading and stabilizing four kinds of circuits.
(1) pressure relief circuit: in the system do not want the pressure or as long as the low pressure, through the pressure relief circuit to make the system pressure drop to zero pressure or low pressure.
(2) Pressure stabilizing circuit: used to reduce or absorb the pressure fluctuation generated in the local range of the system to keep the system pressure stable, such as the use of accumulators in the circuit.
(3) pressure regulating circuit: this circuit with a relief valve to regulate the maximum constant pressure of the hydraulic source, the relief valve plays this role. When the pressure is greater than the set pressure of the relief valve, the relief valve opening is increased to reduce the output pressure of the hydraulic pump to maintain a basic constant system pressure.
(4) Variable pressure circuit: used to change the pressure of the local range of the system, such as in the circuit connected to a pressure reducing valve can make the pressure reducing valve after the pressure reduction; connected to a booster, the pressure after the booster can be higher than the hydraulic source pressure.
