Directional control valves (DCVs) determine the path of fluid flow in hydraulic systems. There are several types of DCVs classified by fluid path, design characteristics, control method, and construction of internal moving parts. DCVs include check valves, shuttle valves, two-way valves, three-way valves, and four-way valves. DCVs can be actuated manually, mechanically, with a solenoid, or with a pilot signal. The simplest DCV is a check valve, which allows uni-directional flow. A poppet check valve uses a spring-loaded poppet to control flow direction, while a pilot-operated check valve uses a pilot signal to control flow in the
This document discusses spool actuation methods for directional control valves. It begins by introducing the three main types of valves: directional control valves, pressure control valves, and flow control valves. It focuses on directional control valves, which determine the fluid flow path. There are two main types of spools: sliding and rotary. Spool actuation can be manual, mechanical, solenoid, hydraulic, pilot-operated, electric, fluidic, or indirect. Common actuation methods include manual handles, linkages, solenoids, and applying a pilot pressure signal. Directional control valves provide advantages such as being innovative, versatile, compact, and reliable.
3 valve shafts pneumatics and hydraulicsaman520305
Control valves determine the direction and flow of fluid in hydraulic circuits. There are three main types: directional control valves, pressure control valves, and flow control valves. Directional control valves include check valves, shuttle valves, and multi-way valves which control fluid flow paths. Pressure control valves such as relief valves, sequence valves, and pressure reducing valves maintain safe pressure levels. Flow control valves regulate fluid flow rates and actuator speeds. Proper use of control valves is important for safe and efficient operation of hydraulic systems.
Directional control valves (DCVs) direct hydraulic fluid flow and are categorized by the number of ports and positions of the internal spool. Common types include 2-way 2-position and 4-way 3-position valves. DCVs are usually actuated electrically via solenoids or hydraulically. Check valves allow fluid flow in one direction only and are used to hold pressure or for safety. Pilot-operated check valves are remotely controlled by a directional valve via a pilot pressure line.
This document discusses various types of hydraulic and pneumatic control elements. It focuses on flow control valves and their purposes.
Flow control valves regulate fluid flow and include pressure control valves, flow control valves, and direction control valves. Pressure control valves such as relief valves and reducing valves maintain system pressure. Flow control valves include compensated and non-compensated types to regulate flow rates. Direction control valves include 2/2, 3/2, and 4/3 styles to control fluid direction to actuators. Proper control elements are necessary to ensure safe and efficient operation of hydraulic and pneumatic systems.
Electro hydraulic system Components and their operationSrichandan Subudhi
After this presentation you will be knowing:
1.What are DCVs, its type and their uses
2.About Check Valves and pilot controlled check valves
3.What are solenoid actuated valves and their operation
4.What are proportional solenoid valves and their operation
5.Servo Valve Operation
6.Servo Valve Connector
Hydraulic Valves and Hydraulic System AccessoriesRAHUL THAKER
Hydraulic Valves and Hydraulic System Accessories:
Direction control valves,Pressure control valves, Flow control valves, Non-return valves, Reservoirs,Accumulators, Heating & cooling devices, Hoses. Selection of valves for circuits.
This document discusses various hydraulic actuators and control components. It begins by describing different types of hydraulic cylinders including single acting, double acting, double rod, tandem, and telescopic cylinders. It then discusses cylinder cushioning and mounting. The document next covers various directional control valves including check valves, pilot operated check valves, 3/2 valves, 4/2 valves, and 4/3 valves. It provides details on the construction and operation of each. Finally, the document discusses flow control valves including pressure relief valves and compound pressure relief valves.
Directional control valves (DCVs) determine the path of fluid flow in hydraulic systems. There are several types of DCVs classified by fluid path, design characteristics, control method, and construction of internal moving parts. DCVs include check valves, shuttle valves, two-way valves, three-way valves, and four-way valves. DCVs can be actuated manually, mechanically, with a solenoid, or with a pilot signal. The simplest DCV is a check valve, which allows uni-directional flow. A poppet check valve uses a spring-loaded poppet to control flow direction, while a pilot-operated check valve uses a pilot signal to control flow in the
This document discusses spool actuation methods for directional control valves. It begins by introducing the three main types of valves: directional control valves, pressure control valves, and flow control valves. It focuses on directional control valves, which determine the fluid flow path. There are two main types of spools: sliding and rotary. Spool actuation can be manual, mechanical, solenoid, hydraulic, pilot-operated, electric, fluidic, or indirect. Common actuation methods include manual handles, linkages, solenoids, and applying a pilot pressure signal. Directional control valves provide advantages such as being innovative, versatile, compact, and reliable.
3 valve shafts pneumatics and hydraulicsaman520305
Control valves determine the direction and flow of fluid in hydraulic circuits. There are three main types: directional control valves, pressure control valves, and flow control valves. Directional control valves include check valves, shuttle valves, and multi-way valves which control fluid flow paths. Pressure control valves such as relief valves, sequence valves, and pressure reducing valves maintain safe pressure levels. Flow control valves regulate fluid flow rates and actuator speeds. Proper use of control valves is important for safe and efficient operation of hydraulic systems.
Directional control valves (DCVs) direct hydraulic fluid flow and are categorized by the number of ports and positions of the internal spool. Common types include 2-way 2-position and 4-way 3-position valves. DCVs are usually actuated electrically via solenoids or hydraulically. Check valves allow fluid flow in one direction only and are used to hold pressure or for safety. Pilot-operated check valves are remotely controlled by a directional valve via a pilot pressure line.
This document discusses various types of hydraulic and pneumatic control elements. It focuses on flow control valves and their purposes.
Flow control valves regulate fluid flow and include pressure control valves, flow control valves, and direction control valves. Pressure control valves such as relief valves and reducing valves maintain system pressure. Flow control valves include compensated and non-compensated types to regulate flow rates. Direction control valves include 2/2, 3/2, and 4/3 styles to control fluid direction to actuators. Proper control elements are necessary to ensure safe and efficient operation of hydraulic and pneumatic systems.
Electro hydraulic system Components and their operationSrichandan Subudhi
After this presentation you will be knowing:
1.What are DCVs, its type and their uses
2.About Check Valves and pilot controlled check valves
3.What are solenoid actuated valves and their operation
4.What are proportional solenoid valves and their operation
5.Servo Valve Operation
6.Servo Valve Connector
Hydraulic Valves and Hydraulic System AccessoriesRAHUL THAKER
Hydraulic Valves and Hydraulic System Accessories:
Direction control valves,Pressure control valves, Flow control valves, Non-return valves, Reservoirs,Accumulators, Heating & cooling devices, Hoses. Selection of valves for circuits.
This document discusses various hydraulic actuators and control components. It begins by describing different types of hydraulic cylinders including single acting, double acting, double rod, tandem, and telescopic cylinders. It then discusses cylinder cushioning and mounting. The document next covers various directional control valves including check valves, pilot operated check valves, 3/2 valves, 4/2 valves, and 4/3 valves. It provides details on the construction and operation of each. Finally, the document discusses flow control valves including pressure relief valves and compound pressure relief valves.
application of Direction control valve in automatic transmissionZIYAD AMBALANGADAN
This document discusses directional control valves and their application in automatic transmissions. It begins by defining directional control valves as valves used to control the direction of fluid flow in hydraulic circuits. It then classifies valves based on their construction, number of ports, switching positions, and actuation mechanism. Examples of poppet and spool valves are described. Applications of directional control valves in automatic transmissions include using them to direct fluid flow to engage or disengage clutches based on vehicle speed. In conclusion, directional control valves are used to distribute hydraulic energy and control the start, stop, and direction of pressurized fluid flow.
This document discusses hydraulic circuits used in hydro power plants. It describes how changing the flow through movable guide vanes can increase or decrease the megawatts generated by adjusting the vane angle. This is achieved using a hydraulic circuit called a speed governor. The document then summarizes the main components of hydraulic circuits including valves, pumps, filters, accumulators, actuators, accessories and connecting pipes. It provides examples of different hydraulic valve types including directional control valves, pressure control valves and flow control valves.
Hydraulic valves control the direction and flow of hydraulic fluid in a circuit. There are three main types: directional control valves, which control the direction of fluid flow; flow control valves, which regulate fluid flow; and pressure control valves, which control pressure in different parts of the circuit. Directional control valves specifically are used to direct fluid to outlet ports and can be classified by their internal element, number of ports, positions, actuation method, and center position flow pattern. Common types include check valves, pilot-operated check valves, and multi-port directional valves.
Pressure control valves are used to control and regulate pressure in hydraulic systems. The main types are pressure relief valves and pressure regulators. Pressure relief valves are connected to high and low pressure lines and are used to limit the maximum operating pressure. They contain a spring-loaded poppet that opens to allow fluid to return to the tank when pressure reaches a certain threshold determined by a formula. Directional control valves and flow control valves are also used to direct and regulate fluid flow respectively. Check valves only allow fluid flow in one direction to prevent backflow.
A shuttle valve is a type of valve which allows fluid to flow through it from one of two sources. Generally a shuttle valve is used in pneumatic systems, although sometimes it will be found in hydraulic systems.
- Hydraulic actuators like cylinders are used to convert fluid pressure into mechanical motion or force. Single-acting cylinders produce force in one direction while double-acting cylinders can produce force in both directions.
- Directional control valves include check valves, two/four-way valves, and shuttle valves. They control the direction of fluid flow. Pressure control valves like relief valves limit system pressure while flow control valves regulate fluid flow rate and actuator speed.
- Properly selecting and using hydraulic components like actuators, valves, and linkages allows fluid power systems to efficiently control mechanical processes.
A hydraulic system consists of a reservoir, electric motor, pump, valves, and actuators. The reservoir stores fluid and conditions it by settling contaminants. The electric motor drives the pump, which converts mechanical power into hydraulic energy and delivers pressurized fluid. Valves control the flow and direction of fluid to drive actuators like cylinders and motors, converting hydraulic power into mechanical motion. Hydraulic lines interconnect these components and can affect system performance through friction losses and pressure changes.
Directional control valves are used to control the direction of fluid flow in hydraulic circuits. They contain ports for fluid to enter and exit, and can be classified based on their construction, number of working ports, switching positions, and actuation mechanism. Common types include poppet valves and spool valves. Directional control valves find application in automatic transmissions, where they control fluid flow to engage and disengage clutches or change gear ratios based on vehicle speed. Proper selection and application of directional control valves is important for efficiently distributing hydraulic power in automotive and industrial systems.
The document outlines objectives for understanding fundamental hydraulic principles, reading hydraulic diagrams, and operating hydraulic systems safely and reliably. It discusses advantages like automatic lubrication and precise motion control. It explains Pascal's law of fluid pressure transmission and fundamental principles like flow determining speed. It provides an overview of key hydraulic components like reservoirs, filters, pumps, valves, actuators and their functions. It also covers important concepts like cleanliness levels, contamination sources, and best practices for fluid handling and storage to prevent system contamination.
Hydraulic Systems and Control ComponentsBalasundar P
The document discusses the basic components and types of control valves used in hydraulic systems. It describes the main components of a hydraulic power pack including the hydraulic pump, electric motor, reservoir, fluid, valves, accumulator, filtration and cooling systems. It then explains the purpose and classifications of different types of directional control valves, flow control valves, and pressure control valves. These include rotary spool valves, sliding spool valves, check valves, globe valves, gate valves, and pressure relief valves. Diagrams are provided to illustrate examples of various valve types.
A hydraulic system was developed to actuate a cylinder forwards and backwards using an electronic valve. The system includes a directional valve, pressure transducer, and flow meter connected to a computer interface. It allows monitoring and controlling the cylinder's position. The interface displays pressure, flow rate, and includes controls to move the cylinder or return it to neutral. This provides a test system for developing feedback control of hydraulic cylinders.
Flow-control valves are used to control the speed of actuators by regulating fluid flow rates. They incorporate a pressure compensator to maintain a uniform flow rate regardless of workload changes. Variations include flow-control-and-check valves, which allow reverse free flow, and flow-control-and-overload-relief valves, which limit system pressure. Flow equalizers divide a fluid stream into two equal streams to synchronize the operation of two actuating units.
This document discusses meter-in flow-control circuits. It explains that meter-in circuits allow fluid to enter an actuator, like a cylinder, at a controlled rate to provide smooth movement. However, meter-in circuits may not work for overrunning loads, as a vacuum can form and cause the cylinder to free fall until filled. The document provides diagrams of meter-in circuits and explains how they regulate cylinder speed by metering fluid into the blind end.
Hydraulic control systems have several key components:
1. A prime mover provides mechanical power that is converted by hydraulic pumps into pressurized fluid power.
2. Control valves direct the fluid and regulate parameters like pressure and flow.
3. Actuators convert the fluid power back into mechanical motion or force.
4. Additional components like filters, pipes, and tanks complete the system to precisely control hydraulic powered machines.
- Hydraulic control systems use fluid power to transmit energy and control machines. They consist of major components like a prime mover, pump, control valves, actuators, and piping.
- Pumps convert mechanical energy into hydraulic energy by pressurizing fluid. Control valves direct and regulate fluid flow and pressure. Actuators convert fluid power back into mechanical motion.
- Common control valves include pressure control valves, flow control valves, and directional control valves. Proportional, integral, and derivative controllers provide different control actions by relating system output to error over time.
This presentation provides an overview of hydraulic control systems. It discusses the basic components including pumps, control valves, actuators, and piping. It describes the functions of various pressure control valves, flow control valves, and directional control valves. It also discusses hydraulic power sources like pumps and actuators like cylinders. In summary, the presentation introduces hydraulic control systems, outlines their major components, and describes the purpose and classification of key valves and actuators used in these systems.
Pneumatic systems use compressed air to transmit power and motion. They have advantages like force multiplication, flexibility, durability, and suitability for harsh environments. Pneumatic systems typically use lower power applications compared to hydraulic systems. Main pneumatic components include compressors to produce air, filters and regulators to condition air, cylinders and motors to provide motion, and valves to control flow. Directional control valves are used to switch airflow between ports to actuate cylinders. Common pneumatic circuits are designed using symbolic representations of components to achieve automated control functions.
2 hydraulic motor and control componentDr.R. SELVAM
A hydraulic system uses an incompressible fluid to transmit power through pressurized fluid. It consists of a prime mover, pump, control valves, actuators like hydraulic motors and cylinders, piping and fluid. Control valves like directional valves, flow control valves and pressure control valves are used to control the flow and direction of fluid. Common actuators include hydraulic cylinders which produce linear motion and hydraulic motors which produce rotary motion. Filters and accumulators support the core hydraulic components. Hydraulic systems have applications in industrial machinery, mobile equipment, automobiles, marine vessels and aerospace equipment.
This document discusses pneumatic control systems and air control valves. It describes the main components of a pneumatic control system and categories of air control valves, including directional control valves, non-return valves, flow control valves, pressure control valves, and shut-off valves. It also covers the construction, operation, and sizing of directional control valves.
This document discusses different types of valves used in fluid power systems including directional control valves, pressure control valves, and flow control valves. It describes common valve types such as check valves, pilot-operated check valves, 3-way valves, 4-way valves, relief valves, pressure reducing valves, counterbalance valves, orifice flow control valves, and needle valves. Examples are also provided to illustrate how to calculate cylinder speed using a flow control valve and flow rate using an orifice plate.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
application of Direction control valve in automatic transmissionZIYAD AMBALANGADAN
This document discusses directional control valves and their application in automatic transmissions. It begins by defining directional control valves as valves used to control the direction of fluid flow in hydraulic circuits. It then classifies valves based on their construction, number of ports, switching positions, and actuation mechanism. Examples of poppet and spool valves are described. Applications of directional control valves in automatic transmissions include using them to direct fluid flow to engage or disengage clutches based on vehicle speed. In conclusion, directional control valves are used to distribute hydraulic energy and control the start, stop, and direction of pressurized fluid flow.
This document discusses hydraulic circuits used in hydro power plants. It describes how changing the flow through movable guide vanes can increase or decrease the megawatts generated by adjusting the vane angle. This is achieved using a hydraulic circuit called a speed governor. The document then summarizes the main components of hydraulic circuits including valves, pumps, filters, accumulators, actuators, accessories and connecting pipes. It provides examples of different hydraulic valve types including directional control valves, pressure control valves and flow control valves.
Hydraulic valves control the direction and flow of hydraulic fluid in a circuit. There are three main types: directional control valves, which control the direction of fluid flow; flow control valves, which regulate fluid flow; and pressure control valves, which control pressure in different parts of the circuit. Directional control valves specifically are used to direct fluid to outlet ports and can be classified by their internal element, number of ports, positions, actuation method, and center position flow pattern. Common types include check valves, pilot-operated check valves, and multi-port directional valves.
Pressure control valves are used to control and regulate pressure in hydraulic systems. The main types are pressure relief valves and pressure regulators. Pressure relief valves are connected to high and low pressure lines and are used to limit the maximum operating pressure. They contain a spring-loaded poppet that opens to allow fluid to return to the tank when pressure reaches a certain threshold determined by a formula. Directional control valves and flow control valves are also used to direct and regulate fluid flow respectively. Check valves only allow fluid flow in one direction to prevent backflow.
A shuttle valve is a type of valve which allows fluid to flow through it from one of two sources. Generally a shuttle valve is used in pneumatic systems, although sometimes it will be found in hydraulic systems.
- Hydraulic actuators like cylinders are used to convert fluid pressure into mechanical motion or force. Single-acting cylinders produce force in one direction while double-acting cylinders can produce force in both directions.
- Directional control valves include check valves, two/four-way valves, and shuttle valves. They control the direction of fluid flow. Pressure control valves like relief valves limit system pressure while flow control valves regulate fluid flow rate and actuator speed.
- Properly selecting and using hydraulic components like actuators, valves, and linkages allows fluid power systems to efficiently control mechanical processes.
A hydraulic system consists of a reservoir, electric motor, pump, valves, and actuators. The reservoir stores fluid and conditions it by settling contaminants. The electric motor drives the pump, which converts mechanical power into hydraulic energy and delivers pressurized fluid. Valves control the flow and direction of fluid to drive actuators like cylinders and motors, converting hydraulic power into mechanical motion. Hydraulic lines interconnect these components and can affect system performance through friction losses and pressure changes.
Directional control valves are used to control the direction of fluid flow in hydraulic circuits. They contain ports for fluid to enter and exit, and can be classified based on their construction, number of working ports, switching positions, and actuation mechanism. Common types include poppet valves and spool valves. Directional control valves find application in automatic transmissions, where they control fluid flow to engage and disengage clutches or change gear ratios based on vehicle speed. Proper selection and application of directional control valves is important for efficiently distributing hydraulic power in automotive and industrial systems.
The document outlines objectives for understanding fundamental hydraulic principles, reading hydraulic diagrams, and operating hydraulic systems safely and reliably. It discusses advantages like automatic lubrication and precise motion control. It explains Pascal's law of fluid pressure transmission and fundamental principles like flow determining speed. It provides an overview of key hydraulic components like reservoirs, filters, pumps, valves, actuators and their functions. It also covers important concepts like cleanliness levels, contamination sources, and best practices for fluid handling and storage to prevent system contamination.
Hydraulic Systems and Control ComponentsBalasundar P
The document discusses the basic components and types of control valves used in hydraulic systems. It describes the main components of a hydraulic power pack including the hydraulic pump, electric motor, reservoir, fluid, valves, accumulator, filtration and cooling systems. It then explains the purpose and classifications of different types of directional control valves, flow control valves, and pressure control valves. These include rotary spool valves, sliding spool valves, check valves, globe valves, gate valves, and pressure relief valves. Diagrams are provided to illustrate examples of various valve types.
A hydraulic system was developed to actuate a cylinder forwards and backwards using an electronic valve. The system includes a directional valve, pressure transducer, and flow meter connected to a computer interface. It allows monitoring and controlling the cylinder's position. The interface displays pressure, flow rate, and includes controls to move the cylinder or return it to neutral. This provides a test system for developing feedback control of hydraulic cylinders.
Flow-control valves are used to control the speed of actuators by regulating fluid flow rates. They incorporate a pressure compensator to maintain a uniform flow rate regardless of workload changes. Variations include flow-control-and-check valves, which allow reverse free flow, and flow-control-and-overload-relief valves, which limit system pressure. Flow equalizers divide a fluid stream into two equal streams to synchronize the operation of two actuating units.
This document discusses meter-in flow-control circuits. It explains that meter-in circuits allow fluid to enter an actuator, like a cylinder, at a controlled rate to provide smooth movement. However, meter-in circuits may not work for overrunning loads, as a vacuum can form and cause the cylinder to free fall until filled. The document provides diagrams of meter-in circuits and explains how they regulate cylinder speed by metering fluid into the blind end.
Hydraulic control systems have several key components:
1. A prime mover provides mechanical power that is converted by hydraulic pumps into pressurized fluid power.
2. Control valves direct the fluid and regulate parameters like pressure and flow.
3. Actuators convert the fluid power back into mechanical motion or force.
4. Additional components like filters, pipes, and tanks complete the system to precisely control hydraulic powered machines.
- Hydraulic control systems use fluid power to transmit energy and control machines. They consist of major components like a prime mover, pump, control valves, actuators, and piping.
- Pumps convert mechanical energy into hydraulic energy by pressurizing fluid. Control valves direct and regulate fluid flow and pressure. Actuators convert fluid power back into mechanical motion.
- Common control valves include pressure control valves, flow control valves, and directional control valves. Proportional, integral, and derivative controllers provide different control actions by relating system output to error over time.
This presentation provides an overview of hydraulic control systems. It discusses the basic components including pumps, control valves, actuators, and piping. It describes the functions of various pressure control valves, flow control valves, and directional control valves. It also discusses hydraulic power sources like pumps and actuators like cylinders. In summary, the presentation introduces hydraulic control systems, outlines their major components, and describes the purpose and classification of key valves and actuators used in these systems.
Pneumatic systems use compressed air to transmit power and motion. They have advantages like force multiplication, flexibility, durability, and suitability for harsh environments. Pneumatic systems typically use lower power applications compared to hydraulic systems. Main pneumatic components include compressors to produce air, filters and regulators to condition air, cylinders and motors to provide motion, and valves to control flow. Directional control valves are used to switch airflow between ports to actuate cylinders. Common pneumatic circuits are designed using symbolic representations of components to achieve automated control functions.
2 hydraulic motor and control componentDr.R. SELVAM
A hydraulic system uses an incompressible fluid to transmit power through pressurized fluid. It consists of a prime mover, pump, control valves, actuators like hydraulic motors and cylinders, piping and fluid. Control valves like directional valves, flow control valves and pressure control valves are used to control the flow and direction of fluid. Common actuators include hydraulic cylinders which produce linear motion and hydraulic motors which produce rotary motion. Filters and accumulators support the core hydraulic components. Hydraulic systems have applications in industrial machinery, mobile equipment, automobiles, marine vessels and aerospace equipment.
This document discusses pneumatic control systems and air control valves. It describes the main components of a pneumatic control system and categories of air control valves, including directional control valves, non-return valves, flow control valves, pressure control valves, and shut-off valves. It also covers the construction, operation, and sizing of directional control valves.
This document discusses different types of valves used in fluid power systems including directional control valves, pressure control valves, and flow control valves. It describes common valve types such as check valves, pilot-operated check valves, 3-way valves, 4-way valves, relief valves, pressure reducing valves, counterbalance valves, orifice flow control valves, and needle valves. Examples are also provided to illustrate how to calculate cylinder speed using a flow control valve and flow rate using an orifice plate.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
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1_Control Valves.ppt
1. SUBJECT PRESENTATION: UNIT – 3
HYDARULIC AND PNEUMATIC CONTROL DESIGN
COURSE TYPE & L T P: OPEN ELECTIVE [3 – 1 – 0]
SEMSTER & SUBJECT CODE: 4TH & ME6039
COURSE CREDIT: 04
TOPIC: HYDRAULIC VALVES
(DIRECTIONAL, PRESSURE, FLOW AND PROPORTIONAL CONTROL VALVES)
Instructor
Dr. Gurjeet Singh
MECHANICAL ENGINEERING DEPARTMENT
PUNJAB ENGINEERING COLLEGE
DEEMED TO BE UNIVERSITY
CHANDIGARH-160012
2. Unit – 3: Hydraulic Control Valves
(Directional, Pressure and Flow Control Valves)
Introduction to Directional Control Valve and Its Classifications
Actuating Devices, Check Valves, Shuttle Valves
Detailed Discussion on Directional Control Valves
Applications of Directional Control Valves
Mounting of Directional Control Valves
Materials of Directional Control Valves
Pressure and Flow Control Valves
3. Learning Objectives
Directional Control Valves
Upon completion of this chapter, the student should be able to:
List different types of valves used in fluid power.
Explain various classifications of directional control valves.
Describe the working and construction of various direction control valves.
Identify the graphic symbols for various types of direction control valves.
Explain the different applications of direction control valves.
Explain the working principle of solenoid-actuated valves.
Evaluate the performance of hydraulic systems using direction control
valves
4. Introduction
One of the most important considerations in any fluid power system is
control. If control components are not properly selected, the entire system
does not function as required. In fluid power, controlling elements are called
valves.
There are three types of valves:
Directional control valves (DCVs): They determine the path through which
a fluid transverses a given circuit.
Pressure control valves: They protect the system against overpressure,
which may occur due to a sudden surge as valves open or close or due to an
increase in fluid demand.
Flow control valves: Shock absorbers are hydraulic devices designed to
smooth out pressure surges and to dampen hydraulic shock.
5. Introduction
In addition, the fluid flow rate must be controlled in various lines of
a hydraulic circuit. For example, the control of actuator speeds can
be accomplished through use of flow control valves.
Non-compensated flow control valves are used where precise speed
control is not required because the flow rate varies with pressure
drop across a flow control valve.
It is important to know the primary function and operation of various
types of control components not only for good functioning of a
system, but also for discovering innovative methods to improve the
fluid power system for a given application.
6. Types of Directional Control Valves {L15,L16,L17}
Based on Fluid Path:
1. Check Valve, Shuttle Valve
2. Two /Three / Four Way Valve
3. Pilot Operated DCV
Based on Design Characteristics:
1. Internal mechanism, Number of Switching Positions (2/3)
2. Number of Connecting Ports / Ways, Actuation Method.
Based on Control Method:
1. Direct Control: Spool Valve, Indirect Control: Solenoid valve
Based on Construction of Internal Moving Parts
1. Rotary Spool Valve
2. Sliding Spool Valve
8. Types of Flow Control Valves {L20, L21}
Non Pressure Compensated Valve
Needle Type Flow Control Valve
Needle Type Integrated Check Valve
2. Pressure Compensated Valve
3. Speed Control Circuit
Meter-In Circuit
Meter-Out Circuit
Bleed Off Circuit
I. For Both Directions
II. For Inlet to Cylinder or Motor
9. Directional Control Valves
A valve is a device that receives an external signal (mechanical, fluid pilot
signal, electrical or electronics) to release, stop or redirect the fluid that flows
through it.
The function of a DCV is to control the direction of fluid flow in any hydraulic
system. A DCV does this by changing the position of internal movable parts.
To be more specific, a DCV is mainly required for the following purposes:
1. To start, stop, accelerate, decelerate and change the direction of motion of a
hydraulic actuator.
2. To permit the free flow from the pump to the reservoir at low pressure when
the pump’s delivery is not needed into the system.
3. To vent the relief valve by either electrical or mechanical control.
4. To isolate certain branch of a circuit.
10. Classification of DCVs based Fluid Path
Based on fluid path, DCVs can be classified as follows:
Check valves.
Shuttle valves.
Two-way valves.
Three-way valves.
Four-way valves.
Classification of DCVs based on Design Characteristics
An internal valve mechanism that directs the flow of fluid. Such a mechanism can
either be a poppet, a ball, a sliding spool, a rotary plug or a rotary disk.
Number of switching positions (usually 2 or 3).
Number of connecting ports or ways.
Method of valve actuation that causes the valve mechanism to move into an alternate
position.
11. Classification of DCVs based on the Control Method
Direct controlled DCV:A valve is actuated directly on the valve spool. This is
suitable for small-sized valves.
Indirect controlled DCV:A valve is actuated by a pilot line or using a solenoid or by
the combination of electrohydraulic and electro-pneumatic means. The use of
solenoid reduces the size of the valve. This is suitable for large-sized valves.
Classification of DCVs based on the Construction of Internal Moving Parts
Rotary spool type: In this type, the spool is rotated to change the direction of fluid. It
has longitudinal grooves. The rotary spools are usually manually operated.
Sliding spool type: This consists of a specially shaped spool and a means of
positioning the spool. The spool is fitted with precision into the body bore through
the longitudinal axis of the valve body. The lands of the spool divide this bore into a
series of separate chambers. The ports of the valve body lead into these chambers
and the position of the spool determines the nature of inter-connection between the
ports.
12. The switching position, flow direction, and port for different
configurations is represented in Table 1.1. Two-way, three-way,
four-way and five-way representation is shown in Table 1.2.
13. Symbolic Notations for Directional Control Valves
This Table shows:
1. switching position,
2. flow direction, and
3. Port for different configurations
18. Symbolic Notations for Directional Control Valves
1. Each different switching position is shown by a square.
2. Flow directions are indicated by arrows.
3. Blocked ports are shown by horizontal lines.
4. Ports are shown in an appropriate flow direction with line arrows
19. Actuating Devices
Direction control valves may be actuated by a variety of methods.
Actuation is the method of moving the valve element from one position
to another.
There are four basic methods of actuation: Manual, mechanical,
solenoid-operated and pilot-operated.
Several combinations of actuation are possible using these four basic
methods. Graphical symbols of such combinations are given in Table.
Manually Operated: In manually operated DCVs, the spool is shifted
manually by moving a handle pushing a button or stepping on a foot
pedal. When the handle is not operated, the spool returns to its original
position by means of a spring.
20. Actuating Devices
Mechanically Operated: The spool is shifted by mechanical
linkages such as cam and rollers.
Solenoid Operated: When an electric coil or a solenoid is
energized, it creates a magnetic force that pulls the armature into
the coil. This causes the armature to push the spool of the valve.
Pilot Operated: A DCV can also be shifted by applying a pilot
signal (either hydraulic or pneumatic) against a piston at either
end of the valve spool. When pilot pressure is introduced, it
pushes the piston to shift the spool.
21.
22. Types of Directional Control Valves {L15,L16,L17}
Based on Fluid Path:
1. Check Valve, Shuttle Valve
2. Two /Three / Four Way Valve
3. Pilot Operated DCV
Based on Design Characteristics:
1. Internal mechanism, Number of Switching Positions (2/3)
2. Number of Connecting Ports / Ways, Actuation Method.
Based on Control Method:
1. Direct Control: Spool Valve, Indirect Control: Solenoid valve
Based on Construction of Internal Moving Parts
1. Rotary Spool Valve
2. Sliding Spool Valve
23. Check Valve
The simplest DCV is a check valve. A check valve allows flow in one
direction, but blocks the flow in the opposite direction.
It is a two-way valve because it contains two ports.
Figure shows the graphical symbol of a check valve along with its no-
flow and free-flow directions.
In the same figure, a light spring holds the ball against the valve seat.
Flow coming into the inlet pushes the ball off the seat against the light
force of the spring and continues to the outlet.
A very low pressure is required to hold the valve open in this direction.
If the flow tries to enter from the opposite direction, the pressure pushes
the ball against the seat and the flow cannot pass through.
25. Raising and lowering large weights using Check Valve
(a Extend Cylinder; (b) Hold Cylinder; (c) Return Cylinder.
26. Advantages of a Poppet Valve
Virtually zero leakage in closed position.
Poppet elements do not stick even when left under pressure for long periods.
Fast, consistent response time: typically 15 millisecond.
Disadvantages of a Poppet Valve
Axial pressure balance is impossible and considerable force may be needed
to open the poppet against the flow at a high pressure. This limits valves
that have direct mechanical actuation to low flow duties.
Generally individual poppets are required for each flow path that
significantly increases the complexity of multi-port valves.
Lapping and super finishing of valves add cost.
27. Pilot – Operated Check Valve
A pilot-operated valve along with its symbol is shown in Fig. above. This type of
check valve always permits free flow in one direction but permits flow in the
normally blocked opposite direction only if the pilot pressure is applied at the
pilot pressure point of the valve.
The check valve poppet has the pilot piston attached to the threaded poppet stem
by a nut.
The light spring holds the poppet seated in a no-flow condition by pushing
against the pilot piston.
The purpose of the separate drain port is to prevent oil from creating a pressure
build-up at the bottom of the piston.
The dashed line in the graphical symbol represents the pilot pressure line
connected to the pilot pressure port of the valve.
Pilot check valves are used for locking hydraulic cylinders in position.
29. Shuttle Valve
A shuttle valve allows two alternate flow sources to be connected in a one-branch
circuit. The valve has two inlets P1 and P2 and one outlet A.
Outlet A receives flow from an inlet that is at a higher pressure. Figure shows the
operation of a shuttle valve.
If the pressure at P1 is greater than that at P2, the ball slides to the right and allows
P1 to send flow to outlet A.
If the pressure at P2 is greater than that at P1, the ball slides to the left and P2
supplies flow to outlet A.
One application for a shuttle valve is to have a primary pump inlet P1 and a
secondary pump inlet P2 connected to the system outlet A The secondary pump acts
as a backup, supplying flow to the system if the primary pump loses pressure.
A shuttle valve is called an “OR” valve because receiving a pressure input signal
from either P1 or P2 causes a pressure output signal to be sent to A. Graphical
symbol of shuttle valve is shown in Fig.
30. Shuttle Valve: (a) Flow from left to outlet and (b) flow from right to outlet
Graphical Symbol of
Shuttle Valve
31. Use of shuttle valves to control
single-acting cylinders (forward).
Use of shuttle valves to control
single-acting cylinders (return).
32. 2/2 DCV normally opened.
(a) Ports A and P are
connected when force is not
applied (valve unactuated).
(b) Ports A and P are not
connected when force is
applied.
Two-way–two-position
normally closed DCV. (a)
Ports A and P are not
connected when force is not
applied (valve unactuated).
(b) Ports A and P are
connected when force is
applied (valve actuated).
34. Three-Way Direction Control
3/2-Way DCV (Normally Closed)
Three-way valves either block or allow flow from an inlet to an
outlet. They also allow the outlet to flow back to the tank when the
pump is blocked, while a two-way valve does not. A three-way valve
has three ports, namely, a pressure inlet (P), an outlet to the
system(A) and a return to the tank (T).
Figure shows the operation of a 3/2-way valve normally closed. In its
normal position, the valve is held in position by a spring as shown in
Fig. In the normal position, the pressure port P is blocked and outlet
A is connected to the tank. In the actuated position shown in Fig. The
pressure port is connected to the tank and the tank port is blocked.
35. 3/2-way DCV
(a) Ports A and T are connected when force is not
applied (valve unactuated).
(b) Ports A and P are connected when force is
applied (valve actuated).
36. 3/2-way DCV
(a) Ports A and P are connected when
force is not applied (valve
unactuated).
(b) Ports A and T are connected when
force is applied (valve actuated).
37. Application of 3/2 DCV valve–filling and draining a vessel:
(a) hold; (b) fill; (b) drain.
39. Four-way DCVs are capable of controlling double-acting cylinders and
bidirectional motors.
Figure shows the operation of a typical 4/2 DCV. A four-way has four ports
labeled P,T,A and B.
P is the pressure inlet and T is the return to the tank; A and B are outlets to
the system.
In the normal position, pump flow is sent to outlet B. Outlet A is connected
to the tank.
In the actuated position, the pump flow is sent to port A and port B
connected to tank T. In four-way DCVs, two flows of the fluids are
controlled at the same time, while two-way and three-way DCVs control
only one flow at a time.
Figure shows the complete graphic symbol for a four-way two-piston DCV.
40. Application of 4/2-way valve – control of single-acting cylinder:
(a) return; (b) extend.
42. Solenoid-Actuated Valve
A spool-type DCV can be actuated using a solenoid as shown in Figure. When the
electric coil (solenoid) is energized, it creates a magnetic force that pulls the
armature into the coil. This causes the armature to push on the push pin to move the
spool of the valve.
Like mechanical or pilot actuators, solenoids work against a push pin, which in turn
actuates a spool. There are two types of solenoid designs used to dissipate the heat
developed in electric current flowing in the coil. The first type dissipates the heat
into surrounding air and is referred to as an “air gap solenoid.”
In the second type “wet pin solenoid,” the push pin contains an internal passage
way that allows the tank port oil to communicate between the housing of the valve
and the housing of the solenoid. Wet pin solenoids do a better job in dissipating heat
because the cool oil represents a good heat sink to absorb heat from the solenoid.
As the oil circulates, the heat is carried into the hydraulic system where it can be
easily dealt with.
43.
44. Applications of Pilot-Operated Valve to Control the Table of a Surface Grinder
Figure shows the application of a pilot-operated DCV where the actuation of a
double-acting cylinder is used to reciprocate the table of a surface grinder.
The table is fitted with adjustable stops as shown in the figure. The pilot valve is
a DCV that is actuated by a push button. During the operation when stop S1
hits push button B1, the pilot valve sends a pilot signal to the main valve to shift
the configuration shown in the right envelope of the main valve.
This actuates the double-acting cylinder to extend. At the end of the extension,
stroke S2 hits push button B2, which causes the pilot signal directions to be
reversed. Due to this change in the pilot signal direction, the main valve moves
to the configuration shown in the left envelope of the main valve.
This in turn actuates the double-acting cylinder to retract. Thus, a pilot valve
controls a main valve and the main valve used to control the double-acting
cylinder.
47. Pressure Control Valve
Hydraulic energy is produced as long as the prime mover (usually an
electric motor) drives the pump, and hydraulic pressure develops by
resistance to pump flow.
Hence, the hydraulic system suffers damage if the pump flow is not stopped
or off loaded (recirculate) back to the tank during non-action periods of the
circuit. Non-action periods arise from stalling an actuator, or by reaching
the end of the stroke or the circuit sequence, or during the time-delay
periods of the circuit sequence.
In order to avoid hydraulic system damage, power wastage and overheating
of the hydraulic fluid, circuit designers use a variety of cleverly designed
systems to control maximum system pressure and pump flow during non-
action periods.
48. Pressure Control Valve
Pressure-control valves are used in hydraulic systems to control actuator
force (force = pressure × area) and to determine and select pressure levels
at which certain machine operations must occur. Pressure controls are
mainly used to perform the following system functions:
Limiting maximum system pressure at a safe level.
Regulating/reducing pressure in certain portions of the circuit.
Unloading system pressure.
Assisting sequential operation of actuators in a circuit with pressure
control.
Any other pressure-related function by virtue of pressure control.
Reducing or stepping down pressure levels from the main circuit to a lower
pressure in a sub-circuit.
49. SPRINGS
1 KG
2 KG
3 KG
We know that under increasing
force springs deform more.
61. Introduction To Flow Control Valves
Flow-control valves, as the name suggests, control the rate of flow of a fluid
through a hydraulic circuit.
Flow-control valves accurately limit the fluid volume rate from fixed
displacement pump to or from branch circuits.
Their function is to provide velocity control of linear actuators, or speed
control of rotary actuators.
Typical application include regulating cutting tool speeds, spindle speeds,
surface grinder speeds, and the travel rate of vertically supported loads
moved upward and downward by forklifts, and dump lifts.
Flow-control valves also allow one fixed displacement pump to supply two
or more branch circuits fluid at different flow rates on a priority basis.
62. Introduction To Flow Control Valves
Typically, fixed displacement pumps are sized to supply maximum system
volume flow rate demands.
For industrial applications feeding two or more branch circuits from one
pressurized manifold source, an oversupply of fluid in any circuit operated
by itself is virtually assured.
Mobile applications that supply branch circuits, such as the power steering
and front end loader from one pump pose a similar situation.
If left unrestricted, branch circuits receiving an oversupply of fluid would
operate at greater than specified velocity, increasing the likelihood of
damage to work, hydraulic system and operator.
63. Functions of Flow-Control Valves
Regulate the speed of linear and rotary actuators
Regulate the power available to sub-circuits by controlling
flow to them
Proportionally divide or regulate pump flow to various
branches of circuit
Classification of Flow-Control Valves
Flow-control valves can be classified as follows:
Non-pressure compensated.
Pressure compensated.
65. Non-pressure-compensated flow-control valves are used when the system pressure
is relatively constant and motoring speeds are not too critical.
The operating principle behind these valves is that the flow through an orifice
remains constant if the pressure drop across it remains the same.
In other words, the rate of flow through an orifice depends on the pressure drop
across it.
The disadvantage of these valves is discussed below. The inlet pressure is the
pressure from the pump that remains constant.
Therefore, the variation in pressure occurs at the outlet that is defined by the work
load. This implies that the flow rate depends on the work load. Hence, the speed of
the piston cannot be defined accurately using non-pressure-compensated flow-
control valves when the working load varies.
This is an extremely important problem to be addressed in hydraulic circuits where
the load and pressure vary constantly.
66. Non Pressure Compensated Needle Type Flow Control Valve.
(a) Fully closed; (b) partially opened; (c) fully opened.
67. Schematic diagram of non-pressure-compensated needle-type flow-control valve is
shown in Fig.
It is the simplest type of flow-control valve. It consists of a screw (and needle) inside
a tube-like structure.
It has an adjustable orifice that can be used to reduce the flow in a circuit. The size
of the orifice is adjusted by turning the adjustment screw that raises or lowers the
needle.
For a given opening position, a needle valve behaves as an orifice. Usually, charts
are available that allow quick determination of the controlled flow rate for given
valve settings and pressure drops.
Sometimes needle valves come with an integrated check valve for controlling the
flow in one direction only.
The check valve permits easy flow in the opposite direction without any restrictions.
As shown in Fig. only the flow from A to B is controlled using the needle.
In the other direction (B to A), the check valve permits unrestricted fluid flow.
69. Pressure-compensated flow-control valves overcome the difficulty
caused by non-pressure-compensated valves by changing the size of
the orifice in relation to the changes in the system pressure.
This is accomplished through a spring-loaded compensator spool
that reduces the size of the orifice when pressure drop increases.
Once the valve is set, the pressure compensator acts to keep the
pressure drop nearly constant. It works on a kind of feedback
mechanism from the outlet pressure. This keeps the flow through the
orifice nearly constant.
70. Schematic diagram of a pressure compensated flow-control valve is
shown in Fig. and its graphical symbol in Fig.
A pressure-compensated flow-control valve consists of a main spool
and a compensator spool.
The adjustment knob controls the main spool’s position, which
controls the orifice size at the outlet.
The upstream pressure is delivered to the valve by the pilot line A.
Similarly, the downstream pressure is ported to the right side of the
compensator spool through the pilot line B.
The compensator spring biases the spool so that it tends toward the
fully open position.
71. If the pressure drop across the valve increases, that is, the upstream
pressure increases relative to the downstream pressure, the
compensator spool moves to the right against the force of the spring.
This reduces the flow that in turn reduces the pressure drop and tries
to attain an equilibrium position as far as the flow is concerned.
In the static condition, the hydraulic forces hold the compensator
spool in balance, but the bias spring forces it to the far right, thus
holding the compensator orifice fully open.
In the flow condition, any pressure drop less than the bias spring
force does not affect the fully open compensator orifice, but any
pressure drop greater than the bias spring force reduces the
compensator orifice.
72. Any change in pressure on either side of the control orifice, without a
corresponding pressure change on the opposite side of the control orifice,
moves the compensator spool.
Thus, a fixed differential across the control orifice is maintained at all times.
It blocks all flow in excess of the throttle setting. As a result, flow exceeding
the preset amount can be used by other parts of the circuit or return to the
tank via a pressure-relief valve.
Performance of flow-control valve is also affected by temperature changes
which changes the viscosity of the fluid. Therefore, often flow-control valves
have temperature compensation.
Graphical symbol for pressure and temperature compensated flow-control
valve is shown in Fig.