Hydraulic excavator hydraulic system simple introduction       

According to the driving requirements of excavator working device and various institutions, the combination of various hydraulic components connected by pipeline is called hydraulic system of excavator. Its function is to oil as the working medium, the use of hydraulic pump to the engine's mechanical energy into hydraulic energy and transport, and then through the hydraulic cylinder and hydraulic motor will turn back to the hydraulic energy into mechanical energy, to achieve a variety of actions of excavator.

Basic Requirements

The hydraulic excavator action complex, where institutions often start, braking, reversing, load changes, shock and vibration frequency, and field operations, changes in temperature and location, according to the working characteristics of hydraulic excavator and environmental characteristics, the hydraulic system should meet the following requirements:

1) to ensure that excavator boom, bucket and bucket can be individually action, can also cooperate with each other to achieve compound action.

2) the movement of the working device and the rotation of the turntable can be carried out separately and can be combined to improve the productivity of the excavator.

3) the left and right tracks of the crawler excavator are driven respectively, so that the excavator is easy to walk, flexible to turn, and can be turned on the spot, so as to improve the flexibility of the excavator.

4) ensure the excavator all reversible action, and stepless speed.

5) the excavator work is safe and reliable, and the implementation of components (hydraulic cylinder, hydraulic motor with overload protection etc.) good; rotary mechanism and a walking device has reliable braking and speed; prevent the boom due to weight decreased and the speed with fast sliding slope.

To this end, the hydraulic system should do:

1) has high transmission efficiency, in order to give full play to the dynamic performance and fuel economy of the engine.

2) the hydraulic system and hydraulic components have sufficient reliability under the large load and rapid vibration impact.

3) cooler light vibration attune, reduce the total quantity of heat, so that the host continuous operation of the hydraulic oil temperature does not exceed 80 degrees, or the temperature does not exceed 45 degrees.

4) because the excavator operation site dust, hydraulic oil are easy to be polluted, so hydraulic system sealing performance is better, hydraulic components sensitive to oil pollution is low, the entire hydraulic system to set up the oil filter and dust proof device.

5) using hydraulic or electro-hydraulic servo control device, so that excavators set up automatic control system, thereby improving the excavator technical performance and reduce the labor intensity of the driver.

type

According to the characteristics of hydraulic pump, the hydraulic system used in hydraulic excavator has three types: quantitative system, variable system, quantitative system and variable system.

1) quantitative system

In the quantitative system adopted by hydraulic excavators, the flow is constant, that is, the flow does not change with the load, and usually depends on throttling to adjust the speed. According to the quantity and combination form of oil pump and circuit in quantitative system, it can be divided into single pump single circuit, double pump single loop quantitative system, double pump double loop quantitative system and multi pump multi loop quantitative system.

2) variable system

In the variable hydraulic excavator system, by volume variable to realize stepless speed regulation, there are three kinds of control methods: variable pump fixeddisplacement motor speed control, quantitative pump variable motor speed, variable pump variable motor speed control.

The variable system of hydraulic excavator adopts variable pump and quantitative motor to realize stepless variable, and both are double pump and double circuit. According to whether the variables of the two circuits are related, the system is divided into two parts: the power variable system and the full power variable system. The power of each pump variable system with a mechanical power adjustment, change of flow pump is only influenced by the change of their own pressure, the pressure change has nothing to do with the other circuit, namely the pump two loop independently constant power variable, two pump has a bucket engine output two pump power; full power variable system consists of a power regulating mechanism for regulating the balance of the two pumps, the swing angle is always the same, and synchronous variable flow volume. The total pressure of the system is determined by the change of the flow rate, and the power of the two pumps is different in the range of variables. The regulating mechanism has two forms of mechanical linkage and hydraulic linkage.