Hysteresis Control in Pump-Controlled Systems—A Way to Reduce Mode-Switch Oscillations in Closed and Open Circuits

There is growing interest in using electric motors as prime movers in mobile hydraulic systems. This increases the interest in so-called pump-controlled systems, where each actuator has its own drive unit. Such architectures are primarily appealing in applications where energy efficiency is important and electric recuperation is relevant. An issue with pump-controlled systems is, however, mode-switch oscillations which can appear when the pressure levels in the system are close to the switching condition. In this paper, the mode-switching behavior of different generalized closed and open circuit configurations is investigated. The results show that the choice of where to sense the pressures has a huge impact on the behavior. They also show that, if the pressure sensing components are properly placed, closed and open circuits can perform very similarly, but that mode-switch oscillations still can occur in all circuits. Active hysteresis control is suggested as a solution and its effectiveness is analyzed. The outcome from the analysis shows that active hysteresis control can reduce the risk for mode-switch oscillations significantly.

Research and application of infrared thermography testing technology for large-scale amusement rides

The operation of large-scale amusement rides is directly related to the safety of the passengers. When an accident occurs involving an amusement ride, the social impact is extremely negative. Therefore, the safety requirements for large-scale amusement rides are extremely high. Condition monitoring and fault diagnosis technologies provide effective ways to ensure the safe operation. Infrared thermal imaging is a common inspection and monitoring technology, which is widely used in electrical and hydraulic machinery systems. However, there is little literature about the application of infrared thermography (IRT) in large-scale amusement rides and a lack of analysis and evaluation methods for infrared inspection results. In order to expand this technology to the field of large-scale amusement rides, it is necessary to research the temperature increase characteristics of key components and develop corresponding technical standards. In the current study, the temperature variation characteristics of the electrical and hydraulic systems of large-scale amusement rides are first examined. Subsequently, the first IRT testing standard for amusement rides in China is described, including its main content and technical requirements. Two test cases are provided in this study in order to illustrate the practicability and reliability of infrared thermography testing technology in the large-scale amusement rides industry.

ALGORITHM OF CONTROLLING AN ADAPTIVE HYDRAULIC CIRCUIT FOR MOBILE MACHINES

Hydraulic systems based on adjustable pumps, proportional electrohydraulic equipment and controllers are used in mobile machines. The authors propose a new scheme of the hydraulic system for mobile machines, which provides the auger drilling operation. A number of studies have shown that a certain ratio should be maintained between the frequency of auger rotation and its feed during operation, where the productivity of soil disruption should not exceed the productivity of transporting loose soil from the drilling zone. Ensuring the required ratio between the speed of the auger rotation and its feed is implemented by a controller that works according to a certain algorithm. A nonlinear mathematical model of the hydraulic system was developed to create the algorithm for controller operation and setting. The equations of the mathematical model are solved in the MATLAB-Simulink environment by the Rosenbrock method. As a result of solving the equations for the mathematical model, the dependences of variables describing the state of the hydraulic system on time are obtained. The values of the controller settings are determined at which the hydraulic system works steadily, the error of flow rate stabilization, the time for pressure adjustment and readjustment does not exceed the allowable values. The algorithm for controlling the auger feed value is formed. This algorithm provides the necessary ratio between the auger feed and speed, as well as reducing the feed rate in the case of soil hardness increases. This creates the conditions for uninterrupted pit drilling at full depth and protection of the hydraulic system from overload.

PRINCIPLES OF CONSTRUCTION OF THE GENERALIZED MATHEMATICAL MODEL OF THE HYDRAULIC EXTINGUISHER OF OSCILLATIONS OF THE PASSENGER CAR

The study of the processes associated with the use of working fluids in the elements of hydraulic drives was preceded by studies of the unsteady periodic movement of the working fluid in the pipelines of hydraulic systems. Such processes take place in hydraulic drives and their elements, and are associated with the compressibility of the working fluid. The stability of the operation of hydraulic valves, which are supplied to hydraulic systems in order to maintain, within the required limits, pressures or flow rates, is also largely predetermined by non-stationary hydro mechanical processes occurring in the pipelines of these systems, channels and chambers of hydraulic devices. The peculiarities of the working processes of passive vibration dampers of passenger cars include the interaction of the working fluid with moving parts and its flow through the channels and through the calibrated holes with local artificial resistance. For in-depth analysis of changes in operating parameters, it is necessary to use a mathematical model that should reflect the processes that occur during the operation of the hydraulic device. In the presented article the generalized mathematical model of the hydraulic damper of fluctuations of the passenger car of the НЦ-1100 type is developed. This model takes into account the special operating conditions of the hydraulic shock absorber, which allows you to study the impact of operating parameters on the performance of the device.

Commercial Aircraft Electrification—Current State and Future Scope

Electric and hybrid-electric aircraft propulsion are rapidly revolutionising mobility technologies. Air travel has become a major focus point with respect to reducing greenhouse gas emissions. The electrification of aircraft components can bring several benefits such as reduced mass, environmental impact, fuel consumption, increased reliability and quicker failure resolution. Propulsion, actuation and power generation are the three key areas of focus in more electric aircraft technologies, due to the increasing demand for power-dense, efficient and fault-tolerant flight components. The necessity of having environmentally friendly aircraft systems has promoted the aerospace industry to use electrically powered drive systems, rather than the conventional mechanical, pneumatic or hydraulic systems. In this context, this paper reviews the current state of art and future advances in more electric technologies, in conjunction with a number of industrially relevant discussions. In this study, a permanent magnet motor was identified as the most efficient machine for aircraft subsystems. It is found to be 78% and 60% more power dense than switch-reluctant and induction machines. Several development methods to close the gap between existing and future design were also analysed, including the embedded cooling system, high-thermal-conductivity insulation materials, thin-gauge and high-strength electrical steel and integrated motor drive topology.

Investigation of a Digital Hydraulic Valve Operated by Servo Motors

This paper describes a new type of digital hydraulic valve run by two servo motors. Digital hydraulics is a cutting-edge technology, which saves more exhausted energy than conventional hydraulic valves. It includes conventional valves, but its working principle is different. Similar or different size valves constitute a digital hydraulic valve assembly. When the assigned valves are opened, a certain amount of flow is obtained from the output of the valve assembly. To control a digital hydraulic valve, Pulse Number Modulation (PNM) Control technique is used for equal valve flow rates, while Pulse Code Modulation (PCM) is used for different valve flow rates. Valves are exerted by independently launched electric coils. Previous studies used controller board and external power booster circuits for coils. In this study, a new type of digital hydraulic valve is designed, manufactured, and tested with the PNM method. The studied valve body has two different valve groups. Every group includes 16 equal valves and 1 camshaft rotated by 1 servo motor. The servo motors are controlled by a PLC. The calculated performance index is found to be 5.1ms which is similar to the results of previous studies. The experimental results showed that the cam and servo motor controlled digital hydraulics is applicable to variable speed control hydraulic systems.

Challenges and Solutions for High-Speed Aviation Piston Pumps: A Review

As a core power component, aviation piston pumps are widely used in aircraft hydraulic systems. The piston pump’s power-to-weight ratio is extremely crucial in the aviation industry, and the “ceiling effect” of the PV value (product of compressive stress and linear velocity) limits the piston pump’s ability to increase working pressure. Therefore, increasing the piston pump’s speed has been a real breakthrough in terms of further enhancing the power-to-weight ratio. However, the piston pump’s design faces several challenges under the extreme operating conditions at high speeds. This study reviews several problems aviation axial piston pumps face under high-speed operating conditions, including friction loss, cavitation, cylinder overturning, flow pressure pulsation, and noise. It provides a detailed description of the research state of the art of these problems and potential solutions. The axial piston pump’s inherent sliding friction pair, according to the report, considerably restricts further increasing of its speed and power-to-weight ratio. With its mature technology and deep research base, the axial piston pump will continue to dominate the aviation pumps. Furthermore, breaking the limitation of the sliding friction pair on speed and power density, thus innovating a novel structure of the piston pump, is also crucial. Therefore, this study also elaborates on the working principle and development process of the two-dimensional (2D) piston pump, which is a representative of current high-speed pump structure innovation.

Pact All Electric - One Step Closer to Autonomy

E&P companies are increasingly challenged with cost-effective development or upgrade of remote fields, ensuring crew safety and regulatory requirements for reducing environmental impact. Remote operations and unmanned platforms have significantly lower CO2 emissions and lowerCAPEX and OPEX in areas of sparse infrastructure. Complete electrification of safety critical control systems is key to maintain safe production while digitization, automation and condition based maintenance reduce required on-site personnel. An all-electric wellhead- and production tree valve actuator for handling emergency situations has been developed under a Joint Industry Project by Equinor, Baker Hughes and TECHNI. PACT utilize a completely new, patent pending failsafe mechanism that is inherently safe without requirement for redundancy. PACT contains an embedded controller and sensors with extremely low power consumption rendering it well suited for solar/alternate power sources. A new super-capacitor is under development in partnership with the University of Southeast Norway, that in combination with the fastest failsafe mechanism ever ensure safety in all modes of operation, even with all lines down or consumed by flames. Electric actuators offer significant CAPEX savings over hydraulic actuators by eliminating costly hydraulic control systems and hydraulic lines as well as saving space and weight. Overall system cost is significantly lower than hydraulic systems (Equinor estimates at around USD 2million per well for an unmanned platform) while also reducing emissions and environmental impact. Globally, there are approximately 7000 offshore platforms of which 1600 are unmanned (200 in the Middle East). The existing population of unmanned platforms is undergoing continual upgrades and there are significant cost savings by using the PACT as a drop-in replacement for existing hydraulic systems, while enabling fully digitized, remote control and autonomous operations. Low power consumption, weight and a small footprint renders it equally suited for land wells, including retrofit upgrades without reinforcing infrastructure. PACT is designed to be an integral part of automated and remote-control systems and the modular technology is also being adopted for subsea trees, as well as other mission critical pressure control applications. Given the significant benefits in simplifying operations and reducing cost while improving HSSE, leading E&P companies including Equinor, Total, Aker BP and others have chosen electric operations as future technology platform for both topside and subsea operations. Embedded force-, pressure-, temperature- and vibration sensors enable data-driven, fact- and condition based maintenance. Aggregating real-time and historical data, component- and system models ensures fully remote/autonomous operation with a digital twin. The novel failsafe-mechanism fronts the most reliable action of all times while the patent pending solution ensures closing times down to 1 second. In 2020 the consortium was awarded USD 950 000 in government support funding and in May 2021 PACT won OTC Spotlight on New Technology award. The paper aims to show how the technology works and underline why it will take a place in the future of well control and production.