Dynamics of Positioning Process for Hydraulic Drive Output Link by Distributor with Closed Center

2022 ◽  
pp. 715-723
Author(s):  
V. Sokolov
Keyword(s):  
Hydraulic Drive ◽  
Output Link

scholarly journals Analysis of the Throttle Speed Control Efficiency in Volumetric Hydraulic Drives

2019 ◽  
pp. 13-33
Author(s):  
K. D. Efremova ◽  
V. N. Pilgunov
Keyword(s):  
Control Method ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Movement Speed ◽  
Working Fluid ◽  
Total Efficiency ◽  
Control Methods ◽  
Output Link ◽  
Hydraulic Cylinders ◽  
Load Characteristics

To control a movement speed of the output link of an executive hydraulic engine (hydraulic cylinder or hydraulic motor), volumetric hydraulic drives traditionally use volumetric and throttle control methods. Under volumetric control, a supply unit employs a pressure-regulated positive displacement pump, as a result of which it is impossible or difficult to separate and independently control the movement speed of the output links of the hydraulic cylinders. In case of throttle control, there is a significant dependence of the speed of the output link on the load it overcomes, a low efficiency of the hydraulic drive and hereto related active heating of the working fluid, as well as large energy losses. However, in embodiment, due to lack of an expensive variable pump, this method of control is much cheaper and can be used in a multi-channel hydraulic drive with a centralized supply unit.Depending on the throttling device localization in the hydraulic drive circuit, there are series (primary or secondary control) and parallel (working fluid bypass adjustment) throttle connection schemes. The secondary control scheme, which generates a pressure in the outlet of the executive hydraulic engine, is preferable due to the fact that it provides an increased pressure in both cavities of the executive hydraulic engine and, accordingly, a lack of combined air bubbles in the working fluid. Heat released in the throttle is discharged directly into the tank, and the pressure in the outlet reduces the danger level of the emergency situation consequences in the event of an unauthorized change in the sign of the load to be overcome. The quality of control is, mainly, assessed by the type of load characteristics, i.e. dependences of the output link speed and its developed power on the load to be overcome, as well as by the control efficiency (the total efficiency value of the regulating and executive subsystems of the hydraulic drive). The dependence of the dynamics and kinematics of the hydraulic drive on the control methods are of particular interest.The proposed paper, based on the developed mathematical models and their testing for specific sizes of hydraulic cylinders presents the numerical values of the load characteristics and dependences of the total efficiency on the load value to be overcome. Shows that the speed load characteristic steepness of an executive hydraulic cylinder and the sign of its derivative are determined by the throttle control method. The greatest power developed by the output link of the hydraulic engine is shifted to the loads that are 50 ... 70% of their maximum value.As a result of theoretical studies using numerical calculation methods, a technique has been developed for selecting a throttle control method with an assessment of its quality and efficiency. The results of the conducted studies expand the capabilities to forecast the dynamics and kinematics of the output link of the hydraulic drive at the stage of its engineering design.

Using a Multi - function Pressure Valve in Volumetric Hydraulics Drives

2019 ◽  
pp. 1-14
Author(s):  
K. D. Efremova ◽  
V. N. Pilgunov
Keyword(s):  
Flow Control ◽  
Systems Engineering ◽  
Internal Control ◽  
Real Life ◽  
Hydraulic Drive ◽  
Movement Speed ◽  
Output Link ◽  
Valve Design ◽  
Hydraulic Equipment ◽  
Pilot Valve

The paper deals with using hydraulic equipment for pressure and flow control in volumetric hydraulic drives to control a throttle movement speed of the output link of an executive hydraulic motor. Depending on the type of problem to be solved, hydraulic equipment is divided into the pressure and flow control, and the shutoff and regulating elements used in equipment are divided into those of valve and spool type. The main paper objective is to analyse designs and feasibilities for using a multi-functional pressure valve to solve real-life problems of control in a volumetric hydraulic drive. The paper presents a multi-function indirect pressure valve design of DZ standard size (Rezroth Bosch Group) and its detailed principle of operation. In the multifunctional pressure valve design there are threaded plugs, the combination of which allows us to control the pilot valve, using the pressure in the hydraulic system (internal control) or the pilot valve control from an external pressure source. Pilot drainage to the valve outlet port (internal drainage) or drainage directly to the tank is possible. It is shown that the term “Load Sensing System” that is used in Western equipment to mean “control based on load magnitude” can be correctly used to describe designs for using a multifunctional valve.Issues on setting up internal functional communications of the valve to select feed modes of a pilot valve and its drainage have been fully considered. By examples of using a multifunctional pressure valve, the valve operation capabilities are shown, namely as an overflow valve, a sequence one, its operation in the balancing scheme of the gravity load and as part of a hydraulic drive with alternating load. The use of multi-function pressure valve in presses allows us to increase the pressing force through using the weight of the punch. The article belongs to the category of systems engineering, and the represented options of the using valve can be applied when designing the volumetric hydraulic drives with throttle control of the movement speed of the output link in hydraulic drives.

Impact Assessment of Dynamic Characteristics on the Hydraulic Driven Machinery Operation

2018 ◽  
pp. 1-12
Author(s):  
A. D. Terenteva
Keyword(s):  
Dynamic Error ◽  
Total Error ◽  
Soil Layer ◽  
Hydraulic Drive ◽  
Hydraulic Cylinder ◽  
Working Mechanism ◽  
Automated Control ◽  
Vertical Coordinate ◽  
Construction Machinery ◽  
The Difference

In civil engineering in Russia, trenching for utilities is currently under digging. To perform such works, it is necessary to use high-precision construction machinery, because inaccurate performance of works can lead to the break down of existing utilities, thereby affecting the residents of nearby houses and demanding the additional works for renewal.The most universal labour saver to perform construction works is hydraulic driven single-bucket excavators, which provide up to 38% of works. Therefore, to improve technical characteristics that affect the accuracy of the work performed is an important task.High requirements for the performance of works are defined by existing construction regulations: an allowable soil layer to remain is at most 0.05 m. To fulfil such requirements, an exact assessment of the working mechanism position and a trench profile is necessary.Examination of a manually operated digging process shows that an operator provides operations untimely, however an automated control system can solve this problem. Dynamic phenomena in the working mechanism have the greatest impact on the accuracy of the works performed.To assess the bucket digging edge position accuracy, a mathematical model of the working mechanism has been created. Based on the cycle scheme of the working process, the excessive displacements of the hydraulic cylinder rods under the load are taken into account. By the end of the cycle, the difference between the specified and obtained positions along the vertical coordinate has been 0.0892 m.A dynamic error of the hydraulic drive system of the working mechanism is considered as a sum of the error due to excessive displacements of the hydraulic cylinder rods and the error due to delay of the hydraulic drive, with the latter being calculated for the average time of delay taking into account the data available in the literature. The total error of the bucket digging edge position of the working mechanism is 0.1176 m, which is 2 times more than the value of 0.05 mConformity of all the links with specification requirements does not guarantee compliance with the required displacement accuracy of the bucket digging edge, and, thus, the soil layer to remain in the base of the trench can exceed the regulated value of 0.05 m.

Stabilization of the Speed of the Hydraulic Motor Through Throttle Compensation for Volume Losses

2020 ◽  
Vol 26 (3) ◽  
pp. 126-130
Author(s):  
Krasimir Kalev
Keyword(s):  
Flow Rate ◽  
Hydraulic Drive ◽  
Pressure Change ◽  
Operating Conditions ◽  
Drive System ◽  
Inlet Pressure ◽  
Schematic Diagram ◽  
Hydraulic Characteristics ◽  
Hydraulic Motor ◽  
Flow Through

AbstractA schematic diagram of a hydraulic drive system is provided to stabilize the speed of the working body by compensating for volumetric losses in the hydraulic motor. The diagram shows the inclusion of an originally developed self-adjusting choke whose flow rate in the inlet pressure change range tends to reverse - with increasing pressure the flow through it decreases. Dependent on the hydraulic characteristics of the hydraulic motor and the specific operating conditions.

Application of ultra-high molecular weight polyethylene in a hydraulic drive

2020 ◽  
pp. 77-78
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
High Molecular Weight ◽  
Hydraulic Drive ◽  
Control Valve ◽  
Hydraulic Control ◽  
Hydraulic Motor ◽  
Hydraulic Pump ◽  
Hydraulic Oil ◽  
Ultra High Molecular Weight

The use of ultra-high molecular weight polyethylene (UHMW PE) for the manufacture of various parts, in particular cuffs for hydraulic drives, is proposed. The properties and advantages of UHMW PE in comparison with other polyethylene materials are considered. Keywords ultra-high molecular weight polyethylene, hydraulic pump, hydraulic motor, hydraulic control valve, hydraulic oil, low temperature. [email protected]

Use of bimetallic parts in hydraulic drive pumps

1982 ◽  
Vol 24 (10) ◽  
pp. 734-737 ◽  
Author(s):  
S. Z. Sapozhnikov ◽  
L. A. Perezhogin ◽  
V. N. Kipriyanova
Keyword(s):  
Hydraulic Drive

A Mathematical Model Including Mechanical Structure, Hydraulic and Control of LHDS

Robotica ◽  
2021 ◽  
pp. 1-16
Author(s):  
Guoliang Ma ◽  
Kaixian Ba ◽  
Zhiwu Han ◽  
Zhengguo Jin ◽  
Bin Yu ◽  
...  
Keyword(s):  
Simulation Model ◽  
Hydraulic System ◽  
Inverse Dynamics ◽  
Hydraulic Drive ◽  
Operation Time ◽  
Variable Load ◽  
Mechanical Structure ◽  
Load Characteristics ◽  
Common Problems ◽  
And Control

SUMMARY In this paper, mathematical models of kinematics, statics and inverse dynamics are derived firstly according to the mechanical structure of leg hydraulic drive system (LHDS). Then, all the above models are integrated with MATLAB/Simulink to build the LHDS simulation model, the model not only considers influence of leg dynamic characteristics on hydraulic system but also takes into account nonlinearity, variable load characteristics and other common problems brought by hydraulic system, and solves compatibility and operation time which brought by using multiple software simultaneously. The experimental results show the simulation model built in this paper can accurately express characteristics of the system.

scholarly journals Simulation of adaptive drill machines with hydraulic drive

2020 ◽  
Vol 971 ◽  
pp. 042092
Author(s):  
M A Lemeshko ◽  
V A Zibrov ◽  
S E Bashnyak
Keyword(s):  
Hydraulic Drive
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