Selenoid valves

[Robert128]

I am new at this so forgive me if some of my terms are off. I was wondering can anyone tell me how selenoid valves work in general, or point me to some books or websites to explain them. There seem to be sets of two selenoids per operation. Are there joystick controllers that I could run to them use them to run a backhoe for instance? I understand the manual 1 or 2 position valves.
Any help would be great - Thanks

http://www.tractorbynet.com/forums/attachment.php?attachmentid=160689&stc=1&d=1270408573

 

[kennyd]

I guess I don't understand what you need to know for sure:confused2:

Those are valves that you have now? There is no way I can tell you how they work from just that picture.

 

[J_J]

Solenoid valves use a voltage to operate the valve. It depends on what you are trying to do as to the configuration you should order. Solenoid valves have a normally on, and normally off condition. Different solenoids are designed to operate in a static condition, and when switched to the opposite state, the fluid takes a different path.

Yes, there are electrical joystick units to control solenoid valves. You can control solenoid valves with toggle , momentary, or spring centered, push button, switches, etc.

 

[mmurphy]

Solenoids when energized are basicaly magnets. Enter a metal stem, energize the solenoid, it was like you were manualy pushing the stem.

What appears you have in that picture is 8, 2 way valves hooked up in a manifold that from what I can tell would run 2 cylinders. That type of setup would much better be ran off of microprocessor (P.L.C.) than a joystick. Did it come off of a garbage truck?

 

[mmurphy]

And I would also say no to running a backhoe. Them valves with the solenoid are either wide open or all the way closed. No feathering of control functions.

 

[irvingj]

A basic fact of electricity is that if you have a current passing through a wire, it will create a magnetic field around the wire.

Multiply that effect by using hundreds of turns/wraps of wire, wrapped around a rod-shaped ferrous metal core, and you have an electromagnet. Turn the power on, the core becomes strongly magnetic. Turn the power off and anything "stuck" to it will drop. This is what wrecking yards use to pick up cars.

If the metal core is allowed to slide within the core --placed in a sleeve-- and spring-loaded to normally be slid partway out one end of the wire coils, you have a solenoid. When power is applied, the metal core will be pulled into the the windings with a fair amount of force. This is what's used on pinball machines to hit the ball on the two sides near the bottom of the play field.

As mmurphy pointed out, there's no half-way with these things. Think of the pinball "flappers." If they are used to control a liquid flow, they're either wide open or shut tight. Hope this helps to understand how solenoids work.

 

[AKKAMAAN]

There is two types of electric solenoid controlled valves. On-Off operated and Proportional. Both can be operated with joy-sticks, but only the proportional allows you to control the actuator speed. The On-Off operated operated the same with Joy-stick as with a on-off switch.

A proportional solenoid valve will need a "PLC" type control, between the joystick and the solenoid coil. Proportional solenoid valves need Pulse Width Modulated (PWM) currency, which the PLC can provide.

Usually, an On-Off solenoid valve can not be used for Proportional control, but a proportional solenoid valve can be used for on-off control.


Also as, irvingj mentioned, it is the electric current, amperage, that creates the magnetic force in the coil. That force will move the solenoid and the control valve.

 

[mmurphy]

There is two types of electric solenoid controlled valves. On-Off operated and Proportional. Both can be operated with joy-sticks, but only the proportional allows you to control the actuator speed. The On-Off operated operated the same with Joy-stick as with a on-off switch.

A proportional solenoid valve will need a "PLC" type control, between the joystick and the solenoid coil. Proportional solenoid valves need Pulse Width Modulated (PWM) currency, which the PLC can provide.

Usually, an On-Off solenoid valve can not be used for Proportional control, but a proportional solenoid valve can be used for on-off control.


Also as, irvingj mentioned, it is the electric current, amperage, that creates the magnetic force in the coil. That force will move the solenoid and the control valve.

Would it be safe to say them are more like poppet type valves AKKAMAAN,and can you run them with a proportional solenoid???

 

[J_J]

I am thinking that proportional control sliding spools are the most common.

 

[AKKAMAAN]

Would it be safe to say them are more like poppet type valves AKKAMAAN,and can you run them with a proportional solenoid???

As kennyd said earlier....need more and better info....I just posted for about solenoid valves in general.....

It sure does not look like it is spool valves though....could be poppet valves....Or the pic just shows a an elctro-hydraulic servo unit, and the spool valve is placed somewhere else....

The symbolic drawing from "the book" would help as well....

Robert128: What type of equipment is that valve sitting on just now??