Equation (1) can be simplified according toequation (2). That is, while the hydraulic-gasenergy storage driving system is adopted, thedriving circuit only needs to overcome the inertialforce of the working device, the material gravityin the bucket, and the compensation amount Δpcof the accumulator pressure change. The energyconsumed by the driving system can be greatlyreduced. Under conditions of heavy load diggingand support of the hydraulic excavator, the(pcAc+ΔpcAc) in equation (1) generates the forceacting upward on the working device, hinderingthe digging and the supporting. Therefore, thehydraulic accumulator control valve group isdesigned to disconnect the hydraulic accumulatorfrom the hydraulic cylinder and eliminate theinfluence of the hydraulic-gas energy storage uniton the digging force and the working condition ofthe supporting vehicle under the heavy loaddigging and supporting conditions. When it isnecessary to disconnect the hydraulicaccumulator from the hydraulic cylinder, thevalve 2 is closed. Meanwhile, the valve 3 isopened to make the hydraulic cylinder chamberC have no force. When the boom is lifted, thevalve 3 is closed and the valve 2 is opened. Atthis moment, the hydraulic accumulator isconnected with the cylinder chamber C to providethe balance force and release the stored hydraulicenergy.