Solenoid valves | The Beauty of Engineering

this hydraulic excavator has a very interesting solenoid valve at the heart of its operation the solenoid valve is so crucial that even minor wear and tear on its disc can cause the excavator to jam leading to its failure they are even used in sensor taps the other major industrial applications of the solenoid valve are illustrated here now an interesting question some commonly used motorized valves in the industry are shown here they are working perfectly then why do we need solenoid valves the answer is that the solenoid valves are insanely fast a normal motorized valve takes one second for its operation while the solenoid valve finishes its task in .03 seconds let's explore the impressive engineering behind solenoid valves starting from the simplest one let's see the construction of the simplest solenoid valve possible first keep an iron armature perpendicular to the pipe the armature is free to move as shown place an electromagnet around the armature and also attach a spring at the top of the armature the spring is compressed and it always tries to keep the armature at the bottom when we energize the electromagnet strong magnetic fields will be generated around it the armature will experience a force causing it to move upwards and to align perfectly to the center of the coil the valve is now open and the water flows by when the coil is not energized obviously the compressed spring will close the valve immediately with this design we have achieved a simple two by two solenoid valve it's called a two by two because of its two ports and two operation states on and off you might be wondering how the armature is able to perfectly align to the center of the coil in this offset state the majority of the magnetic field lines deform and pass through the armature the field lines deform because iron provides a low reluctance path which makes the armature act like a temporary magnet thus the armature experiences upward force you might wonder how is that possible when the bottom poles are closer to investigate the reason behind this let's check out the fea result you can observe the field lines are perfectly straight in the top portion and curved at the bottom most importantly the magnetic domains of the bottom side are experiencing a weaker magnetic field compared to the top region this means the induced pole at the bottom is weaker the armature will experience a net upward force and move along our basic design of a solenoid valve is ready to control some fluid flow but there is a small issue due to the fluid pressure in off state the armature can bend resulting in fluid leakage let's make some design modifications to make it more practical first we can shift the coil slightly and the armature more to the top and instead add a solid thick barrier in the flow path now the valve is closed and the fluid won't be able to cross this region this design will ensure that the armature does not bend due to water pressure when the coil energizes the armature will move up and the valve is open now allowing fluid to easily flow through the gap although this design prevents fluid leakage it does come with another small disadvantage the issue here is that in the off condition the fluid pressure can push the armature upwards this means this design will fail in the off state of the valve if the fluid pressure is high which is obviously undesirable the engineers came up with a perfect solution just keep the same fluid pressure on both sides of the armature see how this new design is achieved practically the design engineers used a flexible rubber diaphragm with two holes this diaphragm is screwed with the valve body the closed condition of the valve is shown the tiny red hole on the diaphragm plays a major role here you can see how the fluid reaches both sides of the armature due to this hole this means that when the valve is closed the fluid pressure acting on the armature gets cancelled this perfectly solves the previous problem when the coil is energized the armature will move up and the fluid will escape via the central hole however this is not the same way the valve operates when the armature is raised here the fluid in the armature region escapes and causes a sudden pressure drop this pressure drop is because the outflow via the central hole is higher than the inflow this pressure difference will bend the diaphragm as shown now the fluid can escape directly via the bottom of the diaphragm now our simple 2x2 solenoid valve design is almost over however if you tear down a real 2x2 valve you can see an additional component an iron cap at the top of the cover why is it needed we already learned that after the armature has moved a small distance the diaphragm bends and the valve becomes operational now let's see which design achieves that small distance first here is a competition between a solenoid valve with and without this iron cylinder using the popular fea simulation software em works you can see that the solenoid valve with the extra iron cap reaches that distance in half the time of the other case this obviously reduces the response time of the solenoid valve the reason for the fast movement is that the iron cap produces a strong magnetic pole there you have it we have now designed a quick and efficient 2x2 solenoid valve now let's explore a very popular design the 5x3 solenoid valve let's consider the bucket of this heavy-duty excavator the bucket rotates thanks to a 5x3 solenoid valve it is clear from this animation that when this double acting cylinder's piston moves linearly the bucket rotates by passing pressurized oil in the direction as shown here the piston achieves the expansion movement the oil on the other side of the piston gets expelled through pipe b as it is incompressible now if you want to move the piston backward the pressurized oil should enter through the pipe b this causes oil on the other side to get expelled from pipe a how can we develop a technology to loop the oil such that no oil gets wasted from the system moreover the prime mover of this technology should be a pump which rotates in the same direction the solution is the use of the 5x3 solenoid valve we need an oil storage tank as well the valve has five ports these ports are connected with this arrangement as shown we will understand the logic behind these connections and the valve technology after some time this unit of solenoid valve pump and storage tank is kept inside the excavator body now the operator presses a button to raise the bucket let's see what happens inside our system to see the animation clearly let's move the solenoid system close to the double acting cylinder the armature of the 5x3 valve is placed at both ends of this spool the pump is operating but you can see many leak-proof discs inside the valve in this spool position the discs block the oil flow as the operator energizes the left-sided solenoid coil the armature experiences a force and the spool moves to the left now the oil flow is possible the pressurized oil reaches the piston connected to the bucket and the bucket is raised the oil on the other side returns to the storage tank as shown if we de-energize the coil the spool will return back to the central position because of the spring tension to lower down the bucket we must energize the right-sided solenoid you can see that the spool moves right and diverts the oil flow now the piston experiences a force in the opposite direction and the bucket is lowered don't forget to be a lessex team member by supporting us at patreon or hitting the youtube join button thank you

Channel: Lesics

Views: 995,472

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Id: kNzmJnJorfg

Length: 9min 48sec (588 seconds)

Published: Sat Aug 06 2022