In order to recover the braking energy in the rotary system, the motor of the rotary part is used to drive separately. In order to overcome the shortcomings of the most classical hybrid hydraulic system structure, the closed volume control system is adopted.
The hydraulic system is characterized by the closed volume control system. Because of the closed hydraulic system, the energy saving effect is improved, but the hydraulic cylinder has the disadvantage of low locking precision when the hydraulic pump stops working. In order to overcome this disadvantage, the locking circuit of two-way cover plate type plug-in valve is adopted. In this hydraulic system, there is no oil pump and it is easy to produce cavitation, and hydraulic shock is easy to occur when the valve core position changes.
Closed volume control system is beneficial to energy saving. Because of the lack of energy recovery system (hydraulic motor generator), the energy saving effect is better and the cost is low. The hydraulic system of the new hybrid hydraulic excavator can meet the following conditions. The energy saving effect is the largest, the cost is the lowest, the speed regulation and movement direction conversion of the actuator are realized, the holes and hydraulic shock are eliminated, and the actuator is locked when the hydraulic pump stops working.
