Research On The Cooperativity Of The Medium-sized Hydraulic Excavators’ Loading And Resetting

Entrucking condition is of prime significance in the work conditions of the middle-sized hydraulic excavator. It consists of excavating, loading, unloading and resetting in a cycle structure. Loading and resetting are driven by the boom cylinder and the swing motor, with the working time occupying more than60%of the entrucking time. In order to improve the cooperativity and efficiency of the hydraulic excavator’s loading action, this paper studies the evaluation method of the cooperative action, the coupling characteristics, the control strategies, and the loading characteristics of the hydraulic actuators.The mathematic expression of the evaluation index on two actuators’cooperativity of the hydraulic is proposed based on the related materials, and the coupling matrix as well as the analysis of variance are adopted so as to evaluate how the two actuators affect each other. It is concluded by the experiment that the loading and work attitude of the work equipment both cast a great influence on the cooperativity.According to the principle of the excavator’s loading action and the great influence of the loading on the cooperativity, the sources of the swing motor’s loading are analyzed through modeling. The mathematic model is established on the basis of simplifying the upframe structure model, the frictional torque, the inertia force of spatial structure as well as the change of the moment of inertia according to different work attitude. Strategies for decreasing and optimizing the loading pressure are put forward. Similarly, on the basis of the physical equivalence model, it is found that the loading pressure is determined by the position of the boom cylinder according to Statics, and the functional equations are also worked out for the loading pressure of the boom cylinder and the angle of the boom lifting, the loading pressure of the boom cylinder and the angular velocity, and the loading pressure of the boom cylinder and the equivalent torque.Using the methods of control theory to solve the coupling relationship of the double actuators in the loading action, the flow equation undergoes the linearization and Laplace transform to solve the coupling matrix, the results show that coupling relationship between the two actuator have relationship with two actuators’pressure load, the motor displacement, cylinder cavity area, the spool displacement-flow’s relationship and so on.Based on this, the curve for the ratio of the flow, the loading pressure and the flow is figured out. The efficiency of the cooperative control strategy is proved by the help of AMESim and ADAMS as well as the simulation studies. The simulation studies show that the synergy has been improved to some extent.The results show that compound action’s cooperativity improves4.04%in load case, work efficiency increases6.82%; compound action’s cooperativity improves0.40%in no-load case, work efficiency is improved5.26%.Finally, the mathematical model’s accuracy of the moment of inertia is verified, and the collaborative evaluation of excavator’s loading action is applied to the loading experiment.The evaluation index has been proved to have certain value.