Energy-saving design of variable-displacement bi-directional pump-controlled electrohydraulic system

2020 ◽  
pp. 095965182097389
Author(s):  
Samir Kumar Hati ◽  
Nimai Pada Mandal ◽  
Dipankar Sanyal
Keyword(s):  
Energy Saving ◽  
Absolute Error ◽  
Fast Response ◽  
Maximum Energy ◽  
Radial Clearance ◽  
Simulation Based Design ◽  
Simulation Based ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Axial Piston

Losses in control valves drag down the average overall efficiency of electrohydraulic systems to only about 22% from nearly 75% for standard pump-motor sets. For achieving higher energy efficiency in slower systems, direct pump control replacing fast-response valve control is being put in place through variable-speed motors. Despite the promise of a quicker response, displacement control of pumps has seen slower progress for exhibiting undesired oscillation with respect to the demand in some situations. Hence, a mechatronic simulation-based design is taken up here for a variable-displacement pump–controlled system directly feeding a double-acting single-rod cylinder. The most significant innovation centers on designing an axial-piston pump with an electrohydraulic compensator for bi-directional swashing. An accumulator is conceived to handle the flow difference in the two sides across the load piston. A solenoid-driven sequence valve with P control is proposed for charging the accumulator along with setting its initial gas pressure by a feedforward design. Simple proportional–integral–derivative control of the compensator valve is considered in this exploratory study. Appropriate setting of the gains and critical sizing of the compensator has been obtained through a detailed parametric study aiming low integral absolute error. A notable finding of the simulation is the achievement of the concurrent minimum integral absolute error of 3.8 mm s and the maximum energy saving of 516 kJ with respect to a fixed-displacement pump. This is predicted for the combination of the circumferential port width of 2 mm for the compensator valve and the radial clearance of 40 µm between each compensator cylinder and the paired piston.

Pressure Compensator Design for a Swash Plate Axial Piston Pump

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
N. P. Mandal ◽  
R. Saha ◽  
S. Mookherjee ◽  
D. Sanyal
Keyword(s):  
Critical Role ◽  
Design Procedure ◽  
Swash Plate ◽  
Simulation Based Design ◽  
Displacement Pump ◽  
Popular Pressure ◽  
Variable Displacement ◽  
And Control ◽  
Spool Valve ◽  
Axial Piston

An in-line axial-piston swash-plate pump with pressure compensator is widely used for its fast speed of response and power economy. Although several simulation based design approaches exist to minimize issues like fluid-born noises, ample scope exists for more exhaustive design analysis. The most popular pressure compensator for a variable displacement pump with a spool valve actuating the control and bias cylinders has been taken up here. With an existing comprehensive flow dynamics model, an updated model for swiveling dynamics has been coupled. The dynamics also includes the force containment and friction effects on the swash plate. A design optimization has been accomplished for the pressure compensator. The target of the optimal design has been set as minimizing the transient oscillations of the swash plate, the compensator spool, pressures in the bias and control cylinders along with avoidance of both over-pressurization and cavitation in the bias cylinder. It has been found that the orifice diameters in the spring-side and at the metering port of the spool valve and in the backside of the bias cylinder have critical role in arriving at an optimum design. The study has led to a useful design procedure for a pressure compensated variable displacement pump.

Experimental Testing of a Variable Displacement Pump/Motor That Uses a Hydro-Mechanically Timed Digital Valving Mechanism to Achieve Partial-Stroke Piston Pressurization (PSPP)

2019 ◽  
Author(s):  
Alissa Montzka ◽  
Nathan Epstein ◽  
Michael Rannow ◽  
Thomas R. Chase ◽  
Perry Y. Li
Keyword(s):  
High Pressure ◽  
Experimental Testing ◽  
Power Level ◽  
Mechanical Valve ◽  
Hydraulic Pump ◽  
Stroke Length ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Piston Stroke ◽  
Axial Piston

Abstract This work describes an efficient means to adjust the power level of an axial piston hydraulic pump/motor. Conventionally, the displacement of a piston pump is varied by changing the stroke length of each piston. Since the losses do not decrease proportionally to the displacement, the efficiency is low at low displacements. Here, with partial-stroke piston pressurization (PSPP), displacement is varied by changing the portion of the piston stroke over which the piston is subjected to high pressure. Since leakage and friction losses drop as the displacement is decreased, higher efficiency is achieved at low displacements with PSPP. While other systems have implemented PSPP with electric or cam-actuated valves, the pump described in this paper is unique in implementing PSPP by way of a simple, robust hydro-mechanical valve system. Experimental testing of a prototype PSPP pump/motor shows that the full load efficiency is maintained even at low displacements.

Leakage Based Condition Monitoring and Pressure Control of the Swashplate Axial Piston Pump

2019 ◽  
Author(s):  
Neeraj Kumar ◽  
Bikash Kumar Sarkar ◽  
Subhendu Maity
Keyword(s):  
Hydraulic System ◽  
Pressure Control ◽  
Piston Pump ◽  
Chamber Pressure ◽  
Leakage Flow ◽  
Axial Piston Pump ◽  
Highly Nonlinear ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Axial Piston

Abstract This research mainly focused on the axial piston variable displacement pump, which is the most important part of the fluid power system. The variable displacement axial piston has been found as versatile and flexible for electro-hydraulic applications. Heavy industries such as automobile, aircraft, and mining use an axial piston pump due to its high power to weight ratio, continuous variable power transmission, low inertia, self-lubricating properties, and good controllability. The main challenges with the hydraulic system are highly nonlinear, leakages, unknown external disturbance, etc. The mathematical model of the variable displacement pump along with swashplate control has been developed. The model is used to identify the pump health condition with pressure and flow measurement, i.e., ripple pattern. The pressure and flow ripple will vary from the regular pattern due to wear and tear, i.e., increased leakage flow. The main source of the increase in leakage flow is due to wear in piston and cylinder bore. The piston chamber pressure, kinematical flow, and discharge area model of the pump has been validated with the existing results. The pump pressure control is very much essential for the enhancement of the performance of the electro-hydraulic system. In the present study, a conventional PID controller has been used as a backup to maintain system performance within the permissible faults. The electro-hydraulic system has been employed for swash-plate control of the pump to obtain desire pressure flow at the exit of the pump. MATLAB Simulink has been used for the simulation study of the pump.

Virtually Variable Displacement Hydraulic Pump Including Compressability and Switching Losses

2006 ◽  
Author(s):  
Mark A. Batdorff ◽  
John H. Lumkes
Keyword(s):  
High Speed ◽  
Control Valve ◽  
Switching Control ◽  
Optimum Pressure ◽  
Fast Switching ◽  
Switching Losses ◽  
Swash Plate ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Axial Piston

Hydraulic pumps can be fixed or variable displacement. Fixed displacement pumps are typically smaller, lighter, less expensive, and can be of any design (gear, vane, axial piston, radial piston, ect.)[1]. Variable displacement pumps are often axial piston with an adjustable swash plate. A virtually variable displacement pump (VVDP) is a fixed displacement pump combined with a fast switching control valve that performs the same function as a variable displacement pump. This is done by always pumping full flow, but using the control valve to divert only a certain percentage of flow to the system, and the rest back to tank. A VVDP has several advantages over a traditional variable swash axial piston pump. First, the pump can be of any design, not just axial piston. Second, the flow control bandwidth can be much faster because it is only limited by the bandwidth of the fast switching control valve and system accumulator, not the bandwidth of a swash plate. Third, a VVDP pump can be more efficient because it can operate at its optimum pressure and flow setting. On the downside a VVDP will require a high speed valve. There are also added switching power losses due to constant metering over valves, compressing and decompressing hydraulic oil, and metering during transition between pumping to system and tank. This paper concentrates on modeling these three switching losses.

scholarly journals Energy Saving Strategy of the Variable-Speed Variable-Displacement Pump Unit Based on Neural Network

Procedia CIRP ◽  
2019 ◽  
Vol 80 ◽  
pp. 84-88 ◽  
Author(s):  
Rui Jin ◽  
Haihong Huang ◽  
Lei Li ◽  
Libin Zhu ◽  
Zhifeng Liu
Keyword(s):  
Neural Network ◽  
Energy Saving ◽  
Variable Speed ◽  
Pump Unit ◽  
Displacement Pump ◽  
Variable Displacement

A novel method to design pressure compensator for variable displacement axial piston pump

2018 ◽  
Vol 233 (2) ◽  
pp. 314-334 ◽  
Author(s):  
Nitesh Mondal ◽  
Rana Saha ◽  
Saikat Mookherjee ◽  
Dipankar Sanyal
Keyword(s):  
Energy Saving ◽  
Dynamic Simulation ◽  
Design Procedure ◽  
Design Sensitivity ◽  
Piston Pump ◽  
Experimental Result ◽  
Axial Piston Pump ◽  
Critical Dimensions ◽  
Variable Displacement ◽  
Axial Piston

An innovative design procedure has been formulated by developing a mathematical model for the pressure compensator of an axial piston pump. The compensator provides energy saving by making the pump variable displacement type depending on the system load, thereby providing energy saving by better resource management. The procedure involves simple static design steps to ensure a balanced swiveling torque on the swash plate for specified cut-in and cut-off pressure limits. Adopting the basic pump model from the earlier works, the dynamic model of the pump has been updated by including the compensator dynamics. A design sensitivity analysis through dynamic simulation has been performed that corroborates the need of the design through torque balancing. Also, through dynamic simulation, tolerances of some critical dimensions have been identified. The pressure compensator model has been validated against experimental result obtained from a reference pump.

A Coupled Fluid-Structure Simulation for Variable Displacement Pump Used in Vehicle

2012 ◽  
Vol 249-250 ◽  
pp. 361-365
Author(s):  
Wei Wei Wu ◽  
Jin Guo Li ◽  
He He Zheng ◽  
Zhao Sheng Wu
Keyword(s):  
Energy Saving ◽  
Coupled Analysis ◽  
Fluid Structure ◽  
Ale Method ◽  
Structure Simulation ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Constant Displacement ◽  
Computing Grid ◽  
Moving Fluid

The defects of constant displacement pumps hinder the modern vehicle to achieve its energy saving goals. Variable displacement pump is becoming the focus of research and development. In the paper, the displacement adjusting mechanism in the pump is treated as a rigid, and its motion leads to a continuously deforming and moving fluid domain. ALE method is used in CFD to overcome the difficulties of the fluid-structure interaction exists in the variable displacement pump. The moving regularity of computing grid and the boundary conditions of the ALE method are reasonably specified, to minimize the computing complexity in the coupled analysis. Experiments on prototype prove the performance of the pump in flow rate and energy saving. The results of analysis agree well with the experimental data, and the motion of the displacement adjusting mechanism is analyzed accurately.

scholarly journals A Single Stage Spool Valve for the Pressure Compensator of a Variable Displacement Pump – Design, Dynamic Simulation and Comparative Study With A Real Pump

2021 ◽  
Author(s):  
Nitesh Mondal ◽  
Rana Saha ◽  
Dipankar Sanyal
Keyword(s):  
Comparative Study ◽  
Design Sensitivity ◽  
Single Stage ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Pump Design ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Spool Valve ◽  
Axial Piston

Abstract The study is focused on the design of a simplified spool valve to be incorporated in the pressure compensator of a variable displacement axial piston pump in order to perform a comparative study with a commercial pump having a two stage spool valve in its compensator. The design involves evaluation of the spool size and selection of spring from static equilibrium condition to satisfy cut-in and cut-off pressure. Following the development of dynamic model of the system, a design sensitivity analysis of the spool valve has been carried out through simulation to identify the critical sizes of the parameters, which affect the pump performance. By systematic design, it is possible to have a single stage spool valve controlled pressure compensator that can produce performance of the variable displacement axial piston pump at par with the similar commercially available pump.

scholarly journals Automated Design and Analysis of a Variable Displacement Linkage Motor

2019 ◽  
Author(s):  
Nathaniel J. Fulbright ◽  
Grey C. Boyce-Erickson ◽  
Thomas R. Chase ◽  
Perry Y. Li ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Solution Space ◽  
Torque Ripple ◽  
Automated Method ◽  
Motor Design ◽  
Displacement Pump ◽  
Variable Displacement ◽  
High Torque ◽  
Low Torque ◽  
Axial Piston

Abstract Hydrostatic drives consisting of a variable displacement pump and a low speed high torque (LSHT) motor are frequently used in off-highway vehicles. A variable displacement traction motor is desirable because of the ability to downsize the pump and thereby run the hydrostat at higher efficiency, as well as the possibility of hybridization of the drivetrain. Currently on the market are fixed and discrete speed LSHT radial piston motors and high speed low torque variable displacement axial piston motors. The radial piston motors are displacement dense but are not continuously variable, whereas the axial piston motors are continuously variable but require gearboxes, introducing packaging and robustness concerns. The Variable Displacement Linkage Motor (VDLM) is a LSHT motor that is continuously variable. It offers several benefits over current LSHT motors in that it is highly efficient over its operating range, it has low torque ripple, and it is displacement dense due to its multi-lobed cam and radial packaging. As with the design of any motor, the process is iterative and must be performed whenever performance objectives change. This paper describes an automated method for rapid exploration of the solution space for a variable displacement motor with specific application to the VDLM. This method leads to a motor design that theoretically can achieve 97% efficiency with a torque ripple below 5% at full displacement.

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