Otis Singleton
Electro-hydraulic proportional valves are electrically operated valves that control the flow of hydraulic fluid to an actuator. They are used to adjust flow, pressure, and direction. The increasing use of electronics to control hydraulic systems has led to greater interest in these valves. There are two main types of electro-hydraulic proportional valves: servo valves and servo-proportional valves. These valves use an electronic signal to provide precise control of position, velocity, and force.
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What You'll Learn
- Electro-hydraulic servo valves (EHSV) are electrically operated
- They control hydraulic fluid flow to an actuator
- They are used for precise control of position, velocity, pressure and force
- Proportional valves use electrical feedback, often an LVDT (linear variable differential transformer)
- They have a large input power range, from several hundred mA to over 1 amp
Electro-hydraulic servo valves (EHSV) are electrically operated
EHSVs use an electronic signal to control the movement of a hydraulic cylinder smoothly and precisely. This signal can be either analogue or digital, and it results in a corresponding set of movements in the cylinder. The valves are designed to respond to the amount of current supplied to the solenoid, determining the direction and flow rate of the hydraulic fluid.
EHSVs are known for their accuracy and precision. They have a smaller input power range, typically tens of mA, compared to proportional valves, which operate with input power ranging from several hundred mA to over 1 amp. This lower input power grants them greater control accuracy with lower hysteresis.
In the event of a loss of electrical power, EHSV centering springs return the valve spool to the center position. The valve solenoids can be driven by a variable current power supply or external power amplifier cards designed to maximize valve performance.
EHSVs are commonly used in applications where precise control of position, velocity, and force is required. They are often employed in industrial settings, heavy-duty equipment, and systems requiring accurate motion control. By using electronic signals, EHSVs offer a level of precision that meets the demands of modern hydraulic systems.
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They control hydraulic fluid flow to an actuator
Electro-hydraulic proportional valves are electrically operated valves that control the flow, pressure, and direction of hydraulic fluid to an actuator. They are designed to control the direction and flow rate of hydraulic fluid based on the amount of current supplied to the solenoid. The input power for these valves can range from several hundred mA to over 1 amp, and they provide precise control of position, velocity, and force.
The use of electronics to control hydraulic systems has led to a greater interest in electro-hydraulic proportional valves. These valves are often used in applications that require highly responsive and accurate motion control. They can be direct-operated or pilot-operated, with the latter being used in cases where a higher degree of accuracy and responsiveness is required.
In the event of a loss of electrical power, the centering springs in an electro-hydraulic proportional valve will return the valve spool to the center position. This ensures that the valve fails in a safe and controlled manner. The valve solenoids can be driven by a variable current power supply or by using external power amplifier cards designed to maximize valve performance.
Electro-hydraulic proportional valves are available in a range of sizes and configurations to suit different applications. They can be used in open-loop or closed-loop circuits and are easily integrated into existing systems. These valves offer a high degree of control and accuracy in hydraulic systems, making them a popular choice in various industrial and mechanical applications.
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They are used for precise control of position, velocity, pressure and force
Electro-hydraulic proportional valves are used for precise control of position, velocity, pressure and force. They are electrically operated valves that control the flow of hydraulic fluid to an actuator. The use of electronics to control hydraulic systems has led to a greater interest in these valves.
The input power for these valves is typically large, ranging from several hundred mA to over 1 amp. This means they can have a lower level of control accuracy and higher hysteresis. However, they are still valuable for applications requiring highly responsive and accurate motion control.
These valves are designed to control the direction and flow rate of oil based on the amount of current supplied to the solenoid. In the event of a loss of electrical power, the centering springs will return the valve spool to the centre position. The valve solenoids can be driven by a variable current power supply or by using external Power Amplifier Cards designed to maximise the valves' performance.
Proportional pressure control valves are available for Relief Valve and Pressure Reducing Valve functions. They are a perfect choice due to their large product offering in flow and pressure ranges.
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Proportional valves use electrical feedback, often an LVDT (linear variable differential transformer)
Electro-hydraulic proportional valves are used to adjust flow, pressure, and direction. They are designed to control the direction and flow rate of oil based on the amount of current supplied to the solenoid. These valves may have feedback control, which is often provided by an LVDT (linear variable differential transformer).
An LVDT electronically compares the input signal with spool position and modifies voltage to maintain the same spool position regardless of system changes. The LVDT does not control the repeatability of flow through the valve, as this is determined by factors such as pressure drop, fluid viscosity, and orifice size. However, adding a feedback signal from the actuator can help to reduce speed changes.
The feedback signal from the LVDT is typically a direct current (DC) voltage signal. It compares the input signal with the spool position to ensure that the spool is in the correct position for the desired flow rate. This feedback control allows for precise positioning and speed control of hydraulic actuators.
Proportional valves with LVDT feedback are available in various configurations, such as direct-operated or pilot-operated valves, and can be used in different applications, including hydraulic systems and throttle control. They offer economical control over positioning and speed, with low hysteresis and fast step response times.
In summary, proportional valves with electrical feedback, often provided by an LVDT, offer precise control over spool position, flow rate, and actuator speed in hydraulic systems. This feedback control enhances the accuracy and responsiveness of electro-hydraulic proportional valves.
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$16.97
They have a large input power range, from several hundred mA to over 1 amp
Electro-hydraulic proportional valves are electrically operated valves that control the flow of hydraulic fluid to an actuator. They are used to adjust flow, pressure and direction. These valves are designed to control the direction and flow rate of oil based on the amount of current supplied to the solenoid.
The input power range for proportional valves is typically large, ranging from several hundred mA to over 1 amp. This is in contrast to servo valves, which have a smaller input power range, typically in the tens of mA.
The large input power range of proportional valves makes them suitable for applications that require a wide range of flow rates and operating pressures. For example, HydraForce electro-proportional valves are available for flow rates from 0 to 189 litres per minute and operating pressures from 20 to 350 bar.
Proportional valves are also available with different types of integrated electronics, such as analogue or fieldbus interfaces, and can be designed for highly responsive and accurate motion control. They can be used in both open-loop and closed-loop circuits and are easily integrated into existing systems.
However, it is important to note that proportional valves may have lower control accuracy and higher hysteresis compared to servo valves.
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Frequently asked questions
An electro-hydraulic proportional valve is an electrically operated valve that controls the flow of hydraulic fluid to an actuator.
Electro-hydraulic proportional valves use an electronic signal to provide precise control of position, velocity, pressure, and force. They can be driven by a variable current power supply or by using external Power Amplifier Cards to maximise performance.
There are two main types of electro-hydraulic proportional valves: direct-operated and pilot-operated. Direct-operated valves include the Continental Hydraulics J Series and G Series, while Pilot-Operated valves include the Continental Hydraulics G Series.
Electro-hydraulic proportional valves are used in applications requiring highly responsive and accurate motion control. They are perfect for controlling flow and pressure in hydraulic systems and can be used in both open-loop and closed-loop circuits.
