Research

17 pages, 7813 KiB

Open AccessArticle

Estimating the Useful Energy of a Launcher’s Pneumatic Launch System UAV

by Grzegorz Jastrzębski and Leszek Ułanowicz

Energies 2022, 15(22), 8424; https://0-doi-org.brum.beds.ac.uk/10.3390/en15228424 - 10 Nov 2022

Cited by 1 | Viewed by 1670

The motivation behind solving the issue of estimating the flow parameters of the pneumatic system of a launcher was the need to obtain the take-off energy with a value exceeding 80 kJ. The take-off energy and the initial speed of the unmanned aerial [...] Read more.

The motivation behind solving the issue of estimating the flow parameters of the pneumatic system of a launcher was the need to obtain the take-off energy with a value exceeding 80 kJ. The take-off energy and the initial speed of the unmanned aerial vehicle (UAV) depends on the pressure drop time in the launcher’s pneumatic system. The aim of the research was to estimate the flow parameters of the trigger system of the UAV launchers in order to achieve the shortest time of its operation. Due to the lack of a description of the selection of pneumatic elements and their flow characteristics in the available literature, the article attempts to analytically describe the air flow through pneumatic units. The trigger system is described using the sonic conductivity and the critical pressure ratio. Due to the lack of numerical data on the flow parameters of pneumatic units, a test stand was designed and constructed to determine these parameters. The values of the sound conductivity and the critical pressure ratio were determined for each of the pneumatic units and for the entire system. The proposed method makes it possible to determine the relationship between the operating time and the values of the flow parameters of the pneumatic launch tube release system. It also provides guidelines for design and technological solutions for the trigger system of any pneumatic launcher. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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21 pages, 7982 KiB

Open AccessArticle

Influence of Hydraulic Drivetrain Configuration on Kinematic Discrepancy and Energy Consumption during Obstacle Overcoming in a 6 × 6 All-Wheel Hydraulic Drive Vehicle

by Mirosław Przybysz, Marian Janusz Łopatka, Arkadiusz Rubiec, Piotr Krogul, Karol Cieślik and Marcin Małek

Energies 2022, 15(17), 6397; https://0-doi-org.brum.beds.ac.uk/10.3390/en15176397 - 01 Sep 2022

Cited by 1 | Viewed by 1273

Abstract

One of the problems limiting the off-road mobility of multi-axle-wheeled vehicles is a kinematic discrepancy, which increases the resistance to motion when negotiating obstacles. This paper presents the results of research on the possibility of reducing the kinematic discrepancy in vehicles with a [...] Read more.

One of the problems limiting the off-road mobility of multi-axle-wheeled vehicles is a kinematic discrepancy, which increases the resistance to motion when negotiating obstacles. This paper presents the results of research on the possibility of reducing the kinematic discrepancy in vehicles with a hydrostatic drive for each wheel by the appropriate selection of hydraulic components—hydraulic motors and flow dividers. Four different configurations of the drivetrain were tested. They used slow-running hydraulic orbital motors and multi-piston radial motors, as well as gear and spool flow dividers. The tests were conducted with computer simulations based on tests that had already been performed to identify hydraulic parts. They allowed for the assessment of the influence of the characteristics of the components and the configuration of the drive system on the differentiation of the rotational speeds of individual wheels, slippage between the wheels and the ground, and the developed driving torques while overcoming obstacles. These values directly translate into the kinematic discrepancy of the system, the ability to overcome terrain obstacles, and energy consumption. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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17 pages, 10003 KiB

Open AccessArticle

Preliminary Experimental Research on the Influence of Counterbalance Valves on the Operation of a Heavy Hydraulic Manipulator during Long-Range Straight-Line Movement

by Marian Janusz Łopatka, Piotr Krogul, Arkadiusz Rubiec and Mirosław Przybysz

Energies 2022, 15(15), 5596; https://0-doi-org.brum.beds.ac.uk/10.3390/en15155596 - 02 Aug 2022

Cited by 4 | Viewed by 1289

Abstract

The effective use of robotic manipulators is particularly important when carrying out hazardous tasks. Often, for this type of mission, manipulators equipped with a hydraulic drive system are used, and their work results primarily from the implementation of precise movements through their effectors. [...] Read more.

The effective use of robotic manipulators is particularly important when carrying out hazardous tasks. Often, for this type of mission, manipulators equipped with a hydraulic drive system are used, and their work results primarily from the implementation of precise movements through their effectors. In heavy manipulators, limiting the uncontrolled movement resulting from high inertia and relatively low stiffness has an impact on the improvement of the control precision. Therefore, the paper presents experimental studies that allow the assessment of the impact of the use of counterbalance valves on the precision and dynamics of a manipulator with a hydrostatic drive system. The tests were carried out for a wide range of effector velocities along a horizontal trajectory, on the basis of which, it was found that it was possible to improve the precision and dynamics of the work of such manipulators due to the precision of the trajectory and pressures in the drive system. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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28 pages, 8042 KiB

Open AccessArticle

Energy Efficiency of Pressure Shock Damper in the Hydraulic Lifting and Leveling Module

by Ryszard Dindorf and Piotr Wos

Energies 2022, 15(11), 4097; https://0-doi-org.brum.beds.ac.uk/10.3390/en15114097 - 02 Jun 2022

Cited by 2 | Viewed by 1582

Abstract

This study evaluates the energy efficiency of pressure shock damping in a hydraulic lifting and leveling (HLL) module of a mobile robotic bricklaying system (RBS). The HLL module includes a servohydraulic actuator (SHA) and a hydraulic shock damper (HSD). The proposed adjustable HSD [...] Read more.

This study evaluates the energy efficiency of pressure shock damping in a hydraulic lifting and leveling (HLL) module of a mobile robotic bricklaying system (RBS). The HLL module includes a servohydraulic actuator (SHA) and a hydraulic shock damper (HSD). The proposed adjustable HSD consists of a hydraulic accumulator circuit (HAC) and proportional damping valve. The frequency characteristics of the impedance and damping efficiency indices were used to evaluate the effectiveness of HSD damping. The dynamic responses of the SHA with and without HSD were analyzed based on a nonlinear state-space model. To control the damping of the pressure shock in the SHA-HSD system, a linear quadratic Gaussian (LQG) controller that follows two measurement signals was implemented. The LQG controller was adapted to the specific dynamic requirements of the SHA-HSD control system and nature of the RBS shock loads. The effectiveness of the LQG controller was evaluated during RBS operation under laboratory conditions. The main purpose of this study was to dynamically stabilize a leveled robot base subjected to shock loading during automatic operation of the RBS. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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27 pages, 7890 KiB

Open AccessArticle

Hydraulic Tests of the PZ0 Gear Micropump and the Importance Rank of Its Design and Operating Parameters

by Piotr Osiński, Adam Deptuła and Marian A. Partyka

Energies 2022, 15(9), 3068; https://0-doi-org.brum.beds.ac.uk/10.3390/en15093068 - 22 Apr 2022

Cited by 4 | Viewed by 1475

Abstract

This article presents the results of hydraulic tests performed for a prototype gear micropump of a new design. The development of modern hydraulic systems is following two directions: the integration of hydraulic and electronic engineering and a reduction in the mass and the [...] Read more.

This article presents the results of hydraulic tests performed for a prototype gear micropump of a new design. The development of modern hydraulic systems is following two directions: the integration of hydraulic and electronic engineering and a reduction in the mass and the dimensions of the system. The scope of this research involved identifying static characteristics of the prototype gear pump, i.e., its efficiency, torque and power. The tests were performed for PZ0 pumps with the following specific deliveries (which are their design parameters), 0.25 cm³/rev, 0.315 cm³/rev, 0.5 cm³/rev, 0.8 cm³/rev, and 1.0 cm³/rev—with two different types of hydraulic oils, Azolla ZS 22 and HL 68. The operating parameters included the rotational speed, the discharge pressure and the flow rate. The obtained research results suggest an application of the decision tree induction-based classification method for identifying the most important design and operating parameters and their values influencing total efficiency. In addition, the article investigates the influence of rotational speed and specific delivery on total efficiency. The total efficiency translates indirectly into the energy consumption of the solution. The criterion of energy consumption is a key parameter for ecological and economical reasons, related mainly to future operating costs. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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14 pages, 8793 KiB

Open AccessArticle

FEM Strength Analysis of Circumferential Compensation with Integrated Lips in Gear Pumps

by Piotr Osiński and Urszula Warzyńska

Energies 2022, 15(7), 2691; https://0-doi-org.brum.beds.ac.uk/10.3390/en15072691 - 06 Apr 2022

Cited by 2 | Viewed by 1432

Abstract

Currently, gear pumps are developed with a aim to increase their efficiency, reduce internal leaks, and increase their working pressures. This development direction requires new solutions which would compensate backlash while ensuring an optimal size of the gaps for the entire range of [...] Read more.

Currently, gear pumps are developed with a aim to increase their efficiency, reduce internal leaks, and increase their working pressures. This development direction requires new solutions which would compensate backlash while ensuring an optimal size of the gaps for the entire range of working pressures. One of the solutions intended to meet this demand is to design circumferential compensation with the so-called integrated lips. The presented backlash compensation method is the result of research performed as part of a project named Designing High-Pressure Gear Pumps. The project was granted funding under path A of the Applied Research Program, contract No. PBS3/A6/22/2015. The research works were performed in the Laboratory of Hydraulic Drives and Vibroacoustics of Machines at Wrocław University of Science and Technology, and in cooperation with Hydrotor SA. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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19 pages, 8592 KiB

Open AccessArticle

Influence of Fluid Compressibility and Movements of the Swash Plate Axis of Rotation on the Volumetric Efficiency of Axial Piston Pumps

by Paweł Załuski

Energies 2022, 15(1), 298; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010298 - 02 Jan 2022

Cited by 14 | Viewed by 1860

Abstract

This paper describes the design of a swash plate axial piston pump and the theoretical models describing the bulk modulus of aerated and non-aerated fluids. The dead space volume is defined and the influence of this volume and the fluid compressibility on the [...] Read more.

This paper describes the design of a swash plate axial piston pump and the theoretical models describing the bulk modulus of aerated and non-aerated fluids. The dead space volume is defined and the influence of this volume and the fluid compressibility on the volumetric efficiency of the pump is considered. A displacement of the swash plate rotation axis is proposed to reduce the dead space volume for small swash plate swing angles. A prototype design of a pump with a displaced axis of rotation of a swash plate with two directions of delivery is presented, in which the capacity is changed by means of a valve follow-up mechanism. Comparative results for a pump with a displaced and a non-displaced swash plate rotation axis are presented, which confirm that displacement of the swash plate rotation axis causes an increase in volumetric efficiency that is apparent for high pressure discharge and small swash plate angles. The determined characteristics were compared with a mathematical model taking into account the compressibility of the fluid in the dead space volume and a satisfactory consistency was obtained. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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21 pages, 43332 KiB

Open AccessArticle

Impact of Hydraulic System Stiffness on Its Energy Losses and Its Efficiency in Positioning Mechanical Systems

by Piotr Dudziński and Aleksander Skurjat

Energies 2022, 15(1), 294; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010294 - 01 Jan 2022

Cited by 1 | Viewed by 2251

Abstract

Hydraulic steering systems for mechanical devices, for example, manipulators or vehicle steering systems, should be able to achieve high positioning precision with high energy efficiency. However, this condition is very often not met in practical applications. This is usually due to the stiffness [...] Read more.

Hydraulic steering systems for mechanical devices, for example, manipulators or vehicle steering systems, should be able to achieve high positioning precision with high energy efficiency. However, this condition is very often not met in practical applications. This is usually due to the stiffness of the hydraulic system being too low. As a result, additional corrections are required to achieve the required positioning precision. Unfortunately, this means additional energy losses in the hydraulic control system. In this study, this problem is presented using the example of a hydraulic steering system for an articulated frame steer vehicle. This hydraulic steering system should provide the required directional stability for road traffic safety reasons. So far, this issue, connected mainly with the harmful phenomenon of so-called vehicle snaking behaviour, has not been solved sufficiently practically. To meet the needs of industrial practice, taking into account the current global state of knowledge and technology, Wrocław University of Science and Technology is performing comprehensive experimental and computational studies on the snaking behaviour of an articulated frame steer wheeled commercial vehicle. The results of these tests and analyses showed that the main cause of problems that lead to the snaking behaviour of this vehicle class is the effective torsional stiffness of the hydraulic steering system. For this reason, a novel mathematical model of the effective torsional stiffness was developed and validated. This model comprehensively took into account all important mechanical and hydraulic factors that affect the stiffness of a hydraulic system, resulting in the examined snaking behaviour. Because of this, it is possible at the design stage to select the optimal parameters of the hydraulic steering system to minimise any adverse influence on the snaking behaviour of articulated frame steer wheeled vehicles. This leads to minimising the number of required corrections and minimising energy losses in this hydraulic steering system. The innovative model presented in the article can be used to optimise positioning accuracy, for example, in manipulators and any mechanical system with hydraulic steering of any system of any mechanical parts. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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22 pages, 8377 KiB

Open AccessArticle

Analysis of the Heating Process of Hydraulic Motors during Start-Up in Thermal Shock Conditions

by Ryszard Jasiński

Energies 2022, 15(1), 55; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010055 - 22 Dec 2021

Cited by 6 | Viewed by 2360

Abstract

Conditions that prevail during harsh winters and hot summers pose a serious challenge for machine designers building devices suitable for operation in extreme weather. It is essential for the designers and the users to define the principles and conditions for the safe operation [...] Read more.

Conditions that prevail during harsh winters and hot summers pose a serious challenge for machine designers building devices suitable for operation in extreme weather. It is essential for the designers and the users to define the principles and conditions for the safe operation of machines and devices with hydraulic drive in low ambient temperatures. Bearing in mind the above, the author tested the hydraulic motors in thermal shock conditions (cold motors were fed with a hot working medium). This enterprise required the design and construction of a specialized stand for testing hydraulic motors, including satellite motors, in thermal shock conditions. The stand was equipped with the apparatus and a system for measuring the temperature of the moving parts of the satellite motor. The experimental tests were conducted in the laboratory of the Faculty of Mechanical Engineering and Ship Technology at Gdańsk University of Technology. The paper presents the results of tests of a correctly and incorrectly operating satellite motor during start-up in thermal shock conditions. The results concerned the course of oil temperatures, temperatures of heated elements, oil pressures, and the pressure drop in the motor. The influence of the oil pressure drop in the motor on its temperature increase was determined. The distributions of the temperature fields of the heated elements of the satellite motor during start-up in thermal shock conditions were derived by means of computer simulation. The utilization of the distribution of the temperature fields of the motor elements enables the evaluation and analysis of the work of this unit. The conducted tests may determine the conditions for the proper operation of hydraulic motors started in thermal shock conditions. Full article

(This article belongs to the Special Issue Energetic Challenges and Perspectives in Advanced Technologies of Hydraulic Systems)

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