Proportional Valves: What Are They And How Do They Work?

Gunjan thakurFebruary 23, 2022

Energy-saving systems are the need of the hour given the current state of the environment, where everybody is working towards developing more sustainable energy sources. However, this is not possible without having a nuanced understanding of the technologies involved in fluid power.

That being said, it is now more important than ever to understand proportional valves and their working principles. Therefore, continue reading as we learn more about proportional valves and the working principle.

What Are Proportional Valves?

Conventionally speaking, proportional valves are basically any valve capable of changing or differentiating their poppet or spool position infinitely between different discrete positions. This enables them to adjust the flow of volumes as many times as needed. The infinite positioning of the spools is made possible with either force-controlled or stroke-controlled solenoids.

Characteristics of this sort make any hydraulic valve ideal for providing changes in the flow or output pressure in the same ratio as the change in the input. For instance, suppose the inputs are tripled for some reason, then the output will also be tripled. These hydraulic valves can be of great use when interconnecting the output from one while using the input as the other.

Working Principle Of Proportional Valves

As one might remember, the experiments in the science class where one applied current to the coil, which in turn created a magnetic field. This consequently repealed or attracted the magnetic material, which seemed much awesome back then. However, the point is that this was the primary principle of a solenoid.

When one increases the current flow, it automatically increases the magnetic field’s strength and the force of repulsion or attraction on any given magnetic material. A solenoid proportional valve is equipped with a unique geometry that ensures the field of strength remains constant irrespective of the current’s level over the magnet’s stroke.

Further, introducing a spring to the equation can counter the magnet’s force as the magnet’s movement compresses it. Hence, the reaction force of the spring will continue to increase until the magnetic force is balanced ideally and there is no more movement.

However, suppose one increases the current, the magnet or the solenoid, in this case, will only move further against the spring until the force is balanced once again. It is further helpful to picture the magnet being attached to the spool within the valve, enabling one to control the flow or pressure with respect to the current applied to the solenoid.

Types Of Hydraulic Proportional Valves

When it comes to hydraulic proportional valves, there are a couple of different variants distinctly suited for varied applications. Therefore, let’s check out these different types of hydraulic proportional valves.

1. Proportional Direction Control Valve: Proportional direction control valves are used to regulate the flow rate of fluid by altering the size or thickness of the flow passage by leveraging a proportional valve controller.
2. Flow Control Valve: These are the type of hydraulic proportional valves generally used to control the pressure and flow rate of liquid flowing through a pipeline. This is usually done to optimize the system’s performance, all thanks to the concept of work, energy, and power in physics.

3. Pressure Relief Valve: Pressure relief valves are used as a safety device as they are engineered to protect a pressurized system or vessel during any ongoing overpressure event. This prevents the system or vessel from exceeding its maximum allowable working pressure by leveraging the properties of a proportional valve.

In Conclusion

As you can see, proportional valves are not as complex as one might think because it is just basic scientific principles at work here. However, these valves are very useful as many now leverage them to develop various machine tools, robotics, hydraulic systems, and much more. Hence leverage this information and acknowledge the significance of these proportional valves.

Frequently Asked Questions:

Q.1. What is a proportional valve?

A – Proportional valves are just like any other valve, except there is no limit when it comes to positioning the spools of these valves. This enables one to adjust the volume of flows without any hassle.

Q.2. What is a proportional solenoid valve?

A – Every proportional valve, a Rexroth proportional valve, or any other valve, requires a signal from a controller called the actuator. The proportional valves that leverage a solenoid to act as an actuator for changing the positions are called a proportional solenoid valve.

Q.3. What is a proportional valve used for?

A – There are many applications of proportional valves, and they are used where there is a requirement for high volume flow, high resolution, or even low hysteresis.

Q.4.How does the proportional pressure relief valve work?

A – Proportional pressure relief valves are used to limit pressure in any hydraulic circuit where the limit is regulated with the help of electronic control. If there is an excessive flow when relieving the pressure, the excessive flow is sent back to the reservoir tank.

Q.5. How does a hydraulic proportional valve work?

A – Hydraulic proportional valves are used to regulate the opening of the flow more proportionally rather than gradually. This is ideally suited for most conventional hydraulic valves.

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Author Bio:

I am Tarun and I am the Managing Director at AstaFluid. I live in Delhi (The national capital of India). My mission is to provide a clean platform for the purchase of Hydraulics and Pneumatics spares and systems and to educate people to select and buy for themselves.