Fluid Power Technology Enhancement in Modern Hydraulic System
Published by : Industrial Automation
Jasbir Singh on how digital technologies will help the world navigate the new normal post the Covid-19 pandemic.
The vision of industry is to transform fluid power and make it compact, effective and efficient. For years now, fluid power system manufacturing companies have developed new energy efficient components in collaboration with design institutions. Despite considerable improvements in the design and metallurgy of components, the hydraulic systems still remain inefficient. The reason is poor overall system functional designs that often compel efficient components to operate in low efficiency regions. Hydraulic systems offer tremendous power densities in operation. In general a hydraulic system delivers more than 10 times power compared to any electric system of the same size and occupies overall less critical space while in operation. The challenge here is that the system has never been efficient as it needs to be. Design institutions are more focused on developing efficient components such as high-speed switching valves, high pressure pumps, quick start/stop motors and high-efficiency hydraulic fluids. The digital transformation and digital technology in fluid power provides new gateways for innovative devices. Adding to the new concept is system integration with ratio opening of fluid control valves of various flow characteristics, use of binary combinations of levers to intelligently control fluid flow and fast switching electro-hydraulic on/off valves. Digital flow control and switching valves improve system performance, efficiency and eliminate chance of leakages.
Hydraulic technological innovation drapes the advancement of hydraulic components, a safe and quick release electrical connection, in-built force lever testing rod, operating procedures and techniques are the most relevant parts of the whole package for the system’s trouble-free operation. Hydraulic system innovations are important because they include improving the development and application of sensors and measurement systems for measurement, monitoring, control and diagnostics of overall systems. Oil pressure, flow temperature, tank level and oil contamination are very critical measurements for overall functioning of hydraulic systems which operate based on feedback signals from equipment. The flow control valve in the hydraulic system regulates the flow rate in specific directions of the hydraulic circuit. Hydraulic control valves are used to control the flow rate to hydraulic coupled motors or cylinders connected to load and thereby regulating the speed. In hydraulic circuits, various options for controlling the flow are achieved, ranging from the simple to the sophisticated, for hybrids systems that may couple with hydraulic valve actuation using sophisticated electronic controls. The purpose of a flow control valve is to regulate the flow rate in a specific portion of a hydraulic circuit.
Flow regulation system components and functions
Operation of a particular hydraulic system is achieved by various devices like orifices, flow regulators, bypass flow regulators, etc. Demand-compensated flow control bypasses full pump output to the tank during the idle portion of the work cycle. Pressure-compensated variable flow-control valve adjusts to varying inlet and load pressures and shut off valve. Pressure relief valve, hydraulic fuse, pressure- and temperature-compensated variable flow-control valve adjusts the orifice size to offset changes in fluid viscosity. Priority valve supplies fluid at a set rate to a primary circuit. Deceleration valve slows load by being gradually closed by the action of the cam mounted on the cylinder load. Linear-type flow divider splits single input into two output flows. Flow dividers can be cascaded in series to control multiple actuator circuits, rotary flow dividers, proportional flow-control valves, pressure-compensated proportional flow-control valves, proportional flow-logic valves and so on many sophisticated add on devices.
Factors that influence performance
Many factors will drastically reduce the operational/service life of hydraulic components and overall systems performance. The solution lies in reliable monitoring and prompt action. Contamination of dust particles, water, or gas ingress are dangerous for the hydraulic system. An appropriate fluid purification must be maintained. Regular online and offline monitoring of the contamination level in oil used for hydraulic systems provides valuable information to the system operator. It enables further analysis of inline filtration efficiency, wear and tear of moving parts in oil submerged systems, ingress of secondary contamination through oil coolers or simply alarm the schedule cleanliness/maintenance of the fluid. Timely and accurate information enables the operator to decide the outage schedule for maintenance. Continuous cleaning of fluid is possible while the system is in operation. Contamination has multiple negative effects on hydraulic systems by accelerated oil aging, shortened fluid life, additive deterioration, increased corrosion, valve cavitation, abrasion, erosion and increased wear tear. Therefore, continuous monitoring by using precise instrumentation and defining the rate of change in level of contamination is necessary for the improved functionality and efficiency of a system.
A range of devices used to measure particulate contamination is an important part of reliable maintenance planning. All diagnoses are made based on gathered information from fluid circuits in real time and accurately. The contamination measuring device is fixed outside but is connected to the machine and its control system. Laser sensors are used to detect particles in the fluid based on the light gate principle. The metal particle monitor and contamination measurement and control are installed as in-line monitoring system for regular operations:
• Automatic particle counting and display of measuring results in every 20 seconds
• Measured data storage in defined storage intervals
• Real time transmission of measured figure via RS 232 bus interface
• Define programmable contamination limit trigger values connected with four potential free relay terminals.
The potential free relays will trigger a relay contact, when process value exceeds the limit value, allowing control functions to operate in the hydraulic and lubrication system. It provides real-time precise diagnosis of a hydraulic system's health; prompt the optimal date for filter element replacement and continuous monitoring of filter performance with respect to the required laid down guidelines by the manufacturer. Installing contamination measurement provides continuous condition monitoring and health diagnosis of hydraulic systems. It enables wear and tear, continuous surveillance and early alarming of damage/breakage, which is essential for smooth operation.
Modern sensor technology with high speed Ethernet connectivity becomes a guided factor of ‘Smart Manufacturing’ on ‘Industry 4.0’ platform.
Digital microprocessors have made a great contribution to automated control, for new component designs and modern manufacturing techniques. Fluid power innovation and shared challenges are guided factors for integration of electronics with fluid power components on development of new efficient systems in the modern world of smart manufacturing.
Acceptance of IoT devices in hydraulic systems
IoT is mainly powered and connected with servers, Ethernet, and wireless devices and presently reaching out to many different fields of industry. Looking at its advantages, IoT’s influence reached the fluid-power systems, i.e., hydraulic and pneumatic systems. Hydraulic product manufacturing companies understand the value of large digitalisation and consider it for the hydraulic product portfolio also. They tried systematically expanding electrohydraulics components/modules having digital interfaces with sensor intelligence. These products exchange data via multi-Ethernet interfaces with other devices and gain fastest controls on equipment performance. Modern hydraulics coupled with intelligent electronic sensors are as intelligent and have the ability superior than most of the electromechanical actuators.
Hydraulic components are being produced with more and more miniature electronics for use in intelligent motion. Smart sensors are used for gathering operating data online for machine learning. This real time gathered data is used for condition monitoring, predictive maintenance, and bus communication for remote access.
Embedded with low-power Bluetooth connectivity for remote valve-controller configuration are new features added where remote operation of equipment is possible without having a direct line of sight. With the evolution of this technology a valve can be installed for optimised operation instead of for tough accessibility.
Wide application surfacing out for hydraulic systems
The technology trends to drive development of smaller valve envelopes with embedded controllers. Lower electrical power consumption with high electrical efficiency is considered for standard, hybrid, and electrical vehicle (EV) systems that are also creating large demand.
Modern hydraulics actuation as the final element of the loop with digital electronics to control offer the best solution. The advantage of fluid technology integrated with the flexibility of modern controls architecture is the modern trend. Hydraulic controls have some unique physical properties, of higher power density, robustness against overload and resistance against shocks. Fluid-power drives are so compact that they need no gearboxes to increase torque or speed. Hydraulic solutions offer substantially increased power relative to total weight compared to electric motors.
There is a massive change of functionality observed in the software architecture of drive technologies. The challenge now is to standardise these across different software protocols, technology interfaces, communication protocols and interfaces which can connect to web services of 3rd party applications and engineering tools. Along with configuration wizard for engineering tools and control algorithms for hydraulic actuators, commissioning engineers do not need knowledge of hydraulics. In future, we shall probably have smart hydraulic fluids, where fluid properties can be changed to suit an application.
Electro-rheological or magneto-rheological fluids might eliminate moving parts from valves. Electro-rheological (ER) and magneto-rheological (MR) fluids, which can transform the fluid from the liquid state to the nearly solid state in milliseconds by applying either an electric or a magnetic field, may revolutionise the hydraulic system performance. The viscosity of such fluids increases when they are subjected to a magnetic field or voltage, so we can implement them to control fluid flow without any moving parts.
Jasbir Singh is an Automation Expert with experience in Factory Automation and Line Automation in a large production house. He is an Implementation Strategist, Business Coach and a regular writer on automation, AI, robotics, digital technology, network communication, IIoT, wireless communication, blockchain and use of advanced digital technology. Jasbir has a long association with industry to improve factory automation in production lines for productivity improvement in India and overseas by advising and also transforming into a digital platform by use of AI. He may be reached by mail at: firstname.lastname@example.org