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Digital hydraulic schematic diagram of working device of loader; 1-Digital pump; 2-Oil source valve; 3-Pilot valve; 4-Boom cylinder; 5-Multi-way valve; 6-Bucket cylinder; 7-Tank.
Source publication
In this paper, a digital hydraulic variable control method based on multi-way valve spool displacement feedback is proposed, which combines the advantages of low cost and high reliability of the loader fixed displacement pump hydraulic system, and the distinguished energy saving effect of the loader variable pump hydraulic system. Based on the prin...
Contexts in source publication
Context 1
... number of stages of the digital pump in this prototype is taken as 4, then the combined displacement of the digital pump is D = a1D1 + a2D2 + a3D3 + a4D4, where there are 16 combinations of displacements, according to the system speed requirements and combined with the engine speed to match the required digital pump displacement of the system. The combination form of pump displacement and its control matrix are as follows: Figure 2 shows the hydraulic schematic diagram of the digital hydraulic working device of the loader, mainly including the digital pump, multi-way valve, hydraulic cylinder, etc. The driver's operating handle changes the oil circuit of the pilot valve, and then changes the position of the multi-way valve spool. ...
Context 2
... valve is the key component of flow control in a hydraulic system of the working device of the loader. Figure 2 shows a typical double multi-way valve from Port P to Port T, which is the bucket linkage and boom linkage. The boom linkage controls the lifting, falling, and floating of the loader boom, and the bucket linkage controls the turnover of the bucket. ...
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This paper will develop a novel electro-hydraulic actuator with energy saving characteristics. This system is able to work in differential configurations through the shifting algorithm of the valves, meaning that this developed system can be adjusted flexibly to obtain the desirable working requirements including the high effectiveness of energy re...
Citations
... The BVs are also simpler and easier to connect to digital controllers. The on/off of the BVs is high frequency, typically 50 Hz or more, and these are these are high-speed on/off valves [27]. BVs are insensitive to contamination and leak-free in state 0. The use of highspeed BVs to control hydraulic stepper actuators (HSAs) results in greater reliability, lower energy consumption, improved positioning accuracy, shorter downtime, lower losses, and lower investment costs. ...
... The pressure drop in the TRV is due to (27), ...
This article presents the conceptual design, operation principle, dynamic modeling, and simulation results of a discrete incremental hydraulic positioning system (DIHPS) intended for use in high-precision, heavy-load industrial automation solutions. An original solution for precise incremental step positioning using DIHPS is proposed, comprising an n-step linear double-acting hydraulic actuator (HA) with a double rod, cylinder sleeve with outflow gaps, binary valves (BVs) bleed-off into the tank, and fixed throttle valves (TRVs) at the inlets of the actuator chambers. The discrete incremental shift of the HA is determined by controlling the opening and closing of the individual BVs, and the step shift of the HA piston stops at the opening location of the BV. A dynamic model of incremental step shift for DIHPS is developed, considering the behavior and relationships of its individual elements. A dynamic model of HA with and without a hydropneumatic accumulator (HPA) is presented. HPA has been shown to effectively dampen piston vibrations and pressure peaks at the HA stop position. The design assumptions, dynamic models, and discrete incremental positioning of the DIHPS are verified by simulation tests and assessed with quantitative indicators. Innovative DIHPSs have significant practical potential in the discrete incremental positioning of heavy loads.
... [107][108][109] Optimization, Fault identification and Simulation Pilot valve parameters optimization techniques. [110][111][112] ...
Hydraulic systems have been widely used due to their high power-to-weight ratio. Despite the growing instances of being superseded by the electromechanical counterparts at low power levels, the market was incapable of presenting alternatives for large-size applications. Additionally, in recent years, the demand for more significant heavy machinery (Mobile & Industrial) has increased, which led to the necessity of even higher flow and pressure Pilot-operated valves, despite the fact that these valves have several issues. One might think the alternative could be developing a hydraulic system that does not rely on Pilot-operated valves, but after decades of research, these systems could not get close to the performance of Pilot-operated Multistage valves. The paper presents a comprehensive study of the progress accomplished from the year 2016 to early 2022 in hydraulic Pilot-operated valves; they are widely employed among ordinary valves, proportional valves, and state-of-the-art digital hydraulics. Higher efficiency will be a primary factor in the success of the new designs. The academia presented several studies to improve the Pilot valves’ performance, but still, they are limited. There are no dramatic developments, and there are only a few upgrades.
... But, when a fine flow needs to be controlled, it is necessary to make the valve opening area as small as possible. Ye [24] and Li [25] compared the pressure-flow characteristics of V-shaped and U-shaped grooves, finding that the Vshaped groove has a better throttling effect and a smaller change in flow with differential pressure. It's easy to fine-tune and smooth running, but prone to cavitation. ...
... In practical optimization problems, there are often multiple conflicting optimization objectives, and single-objective optimization algorithms cannot optimize multiple objectives simultaneously [19,20]. Li [21] adopted the linear weighting method to transform a multiobjective optimization problem considering energy consumption, stroke, and flow range into a single-objective optimization problem. The throttle groove parameters of the multiway valve spool were optimized using a genetic algorithm, which resulted in significantly lower energy consumption, a wider speed range, and a 27% increase in effective stroke. ...
This study proposes a novel approach to optimize the structure of the hinge beam in cubic presses, aiming to enhance the safety and reduce costs. The finite element method is used to analyze the stress distribution of the hinge beam under operating conditions, revealing a significant stress concentration at the oil inlet edge. To optimize the structure, the Taguchi method, the NSGA-II multi-objective optimization algorithm, and the entropy-TOPSIS method are combined to consider both the maximum stress and total weight. The results demonstrate a reduction of 199.121 kg and 11.97 MPa in the total weight and maximum stress of the hinge beam, respectively, representing a decrease of 4.12% and 1.72%. Furthermore, the simulation results of the optimal structure demonstrate a high degree of accuracy, with only 0.27% difference between the algorithm-optimized and simulation values. The proposed optimization method not only improves the efficiency of the optimization, but also avoids the mutual exclusion between the maximum stress and total weight. It significantly improves the reliability of the hinge beam and reduces its manufacturing costs, thereby shortening the development cycle of the new hinge beam.
... (1) Performance regulation of HSVs under complex operating conditions. At present, the application of HSVs is occurring in the automobile [95], engineering machinery [96], and aerospace [97] fields. Different application fields focus on different requirements for the performance of HSVs. ...
As the working conditions of host equipment become more complex and severe, performance improvement and increased intelligence of high speed on/off valves (HSV) are inevitable trends in the development of digital hydraulic technology. The characteristics of HSVs can be regulated by control strategies, which determine the comprehensive performance of the system. This paper discusses the development of control strategies for HSVs. First, the results of research in relation to the discrete voltage and pulse control of single HSVs and the coding control of parallel HSVs are summarized. In addition, the advantages, disadvantages and application scope of different control strategies are analyzed and compared. Finally, the development trends are predicted from the performance regulation, intelligent maintenance, intelligent coding and function programmability.
... However, the use of a compensator also has an impact on the flow characteristics of control valves [14]. It increases the throttle loss of the orifice [15] and is also affected by nonlinear factors such as flow force and friction, resulting in low flow control accuracy [16]- [17]. The fixed pressure drop also limits the flow range of the control valve. ...
There are the problems of low flow control accuracy, small flow control difficulty, and limited flow range in the traditional pressure-compensation flow-control valve. For this, a method of continuous control pressure drop Δprated to control flow-control valve flow is proposed. And the precise control of small flow is realized by reducing the pressure drop Δprated. In the research, the flow-control valve with controllable pressure compensation capability (FVCP) was designed firstly and theoretically analyzed. Then the sub-model model of PPRV and traditional flow-control valve were established and verified through experiments respectively. Finally, the accurate co-simulation model of the FVCP was established. The continuous control characteristics of pressure drop Δprated, the flow characteristics of FVCP, and the influence of different parameters d2 were studied. The research results demonstrate that, compared with the traditional flow-control valve, the designed FVCP can adjust the compensation pressure difference in the range of 0~1.7 MPa in real-time. And the flow rate can be altered within the range of 44%~100% of the rated flow. The diameter d2 of the console shoulder has almost no effect on the compensator operating characteristics.
As the harshness of the underwater operating environment and complexity of underwater tasks gradually increase, underwater hydraulic manipulators with high reliability and precision attract more research attention. To improve the reliability and dynamic performance of the traditional electro-hydraulic proportional valve (EHPV) used in the underwater hydraulic manipulator, an improved electro-hydraulic proportional valve with a discrete pilot stage (DEHPV) is proposed. In the pilot stage, two 2-position 3-way normally open high speed switching valves (HSVs) are used, and the initial oil spring stiffness in the control chamber is large enough to maintain the dynamic performance of the DEHPV. First, the working principle and configuration of the DEHPV are both given, and the coupled electric-magnetic-mechanical-fluid model of the DEHPV is presented. Moreover, a dual-valve hybrid pulse width modulation (DVHPWM) control strategy is proposed to improve the position tracking accuracy of the DEHPV. Furthermore, a co-simulation model of the DEHPV considering the multi-field coupling law is established to study the dynamic characteristics. Extensive experiments are carried out to verify the effectiveness of the proposed structure as well as its good dynamic performance and control accuracy.
The full hydraulic braking systems have gradually replaced the traditional mechanically actuated brake systems due to their increased performance, reliability, and safety. Besides their excellent characteristics, the functional performance of individual components, the correlation of their performance parameters, and energy consumption are not fully explored. In this paper, An Advanced Modeling Environment for performing Simulation of engineering systems (AMESim) simulation model of a fully hydraulic braking system is developed and validated, and the sensitivity of different parameters to the system performance is predicted. The multi-factor comprehensive optimization analysis was carried out from the system level for the first time. The brake energy consumption and interaction time are evaluated through a Genetic Algorithm (GA) considering a multi-factor coupling condition. The optimization results revealed that the outlet pressure and braking pump power are reduced by 35.6%, the energy consumption is reduced by 32.8%, and the braking times are increased by 10%.
