Research on Optimal Control of Excavator Negative Control Swing System

Abstract

In order to improve the energy efficiency and dynamic of negative control swing systems of excavators, this paper proposes a technical scheme of adding two PRVs (pressure reducing valves) to main valve pilot control circuit, which can adjust main value opening arbitrarily according to the working condition. A pump-value compound control strategy was formulated to regulate the system power flow. During swing motor acceleration, main pump and the two PRVs are controlled to match system supply flow with motor demand flow, thereby reducing motor overflow and shortening system response time. During swing motor braking, the channel from motor to tank is opened to release hydraulic brake pressure by controlling PRVs before swing speed reduces to zero, which prevents the motor from reversing and oscillating. A simulation model of 37-ton excavator was established, and the control strategy was simulated. The original and optimized performance of the swing system were compared and analyzed, and results show that the application of new scheme with the compound control strategy can reduce overflow and increase braking stability of the swing system. In addition, system response and speed control performance are also improved when excavator performs a single-swing action.

Developments in energy regeneration technologies for hydraulic excavators: A review

“…Zhang et al [63] added two pressure reducing valves to hydraulic system which could control the displacement of main pump due to the working condition. During swing motor acceleration, the flow rate of main pump was controlled to match with required flow from the swing motor, thereby the motor overflow and system response time were reduced.…”

Experimental and Numerical Analysis of Leakage Characteristics of Proportional Directional Valve

“…The amount of internal fluid leakage between the valve spool and the sleeve is influenced by the radial clearance and the type of spool valve overlap. The overlap size of the individual control edges of the directional valve may vary depending on the requirements of the hydraulic system [5,6]. The actual dimensions of the radial clearance and all functional spool surfaces depend on the accuracy of the manufacturing process.…”

Research on a Novel Multi-pump and Multi-motor Driving System

“…Due to the serious flow loss and throttling loss in the positive flow system, the negative flow control system comes out, which controls the displacement of the pump by setting a flow detection device on the bypass oil circuit, thereby reducing the loss of the bypass oil circuit and solving the problem of large energy consumption. Subsequently, load-sensing technology appeared and was widely used in excavators [12][13][14]. The advantage of load-sensing technology is that when the external load changes, the flow of the pump and valve can be adjusted automatically, so that the hydraulic system can provide the flow and pressure to the pipeline to adapt to the external load, thereby improving energy utilization.…”