Potential energy recovery hydraulic control device for movable arm of excavator

The invention discloses a potential energy recovery hydraulic control device for a movable arm of an excavator. A first hydraulically operated valve is connected with rod cavities of two movable arm oil cylinders which are connected in parallel; a second hydraulically operated valve is connected with a bucket arm oil cylinder; a hydraulic oil path which is connected with rodless cavities of the movable arm oil cylinders is divided into two paths, of which the first path is connected with the second hydraulically operated valve through a hydraulic control one-way valve, an energy accumulator and a first electromagnetic valve and the second path leads to the first hydraulically operated valve through a second electromagnetic valve or leads to a hydraulic motor through a first electromagnetic valve; the output end of the hydraulic motor is connected with a generator. According to the device, the potential energy of the movable arm is rationally recovered and fully utilized, high-pressure return oil produced by the potential energy of the movable arm is input into the energy accumulator to release hydraulic energy and is converged with a main pump oil path to be supplied for the bucket arm oil cylinder; or the hydraulic energy is used for driving the hydraulic motor in a converging manner; the generator is driven by the hydraulic motor to realize conversion from the hydraulic energy to electric energy. The device has the advantages of wide application range, various conversion forms and particularly remarkable energy-saving effect on middle and large-sized excavators.