According to the characteristics of hydraulic pumps, hydraulic systems used in hydraulic excavators generally include quantitative system, variable system and quantitative and variable system.
According to the characteristics of hydraulic pumps, hydraulic systems used in hydraulic excavators generally include quantitative system, variable system and quantitative and variable system.
Quantitative system
In the quantitative system used in hydraulic excavators, the flow is constant, that is, the flow does not change with the load, and the speed is usually adjusted by throttling. According to the quantity and combination form of oil pumps and circuits in the quantitative system, it can be divided into single pump single circuit, double pump single circuit quantitative system, double pump double circuit quantitative system and multi pump multi circuit quantitative system.
Variable system
In the variable system adopted by hydraulic excavator, stepless speed regulation is realized through volume variable, and there are three adjustment modes: variable pump constant motor speed regulation, constant pump variable motor speed regulation, variable pump variable motor speed regulation.
The variable system adopted by hydraulic excavator mostly adopts the combination of variable pump and constant displacement motor to realize stepless variable, and both of them are double pumps and double circuits. According to whether the variables of the two loops are related, it can be divided into power variable system and full power variable system. Each oil pump of the sub power variable system has a power regulating machine, and the flow change of the oil pump is only affected by the pressure change of its own circuit, independent of the pressure change of the other circuit, that is, the oil pumps of the two circuits independently conduct constant power regulating variables, and each of the two oil pumps has a bucket of engine output power; The two oil pumps in the full power variable system are balanced and adjusted by a total power regulating mechanism, so that the swing angle of the two oil pumps is always the same, and the synchronous variable and flow are equal. The total pressure of the system determines the flow change, and the power of the two oil pumps is different within the variable range. Its regulating mechanism has two forms: mechanical linkage and hydraulic linkage.
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