solenoid valve design

[rmetzger]

I'm designing a low profile 3-position system using a DC solenoid(s) to create the motion/forces necessary. To maintain a minimum height - I was planning on using a non-magnetic conical spring (brass/bronze) residing within the bore that will return the plunger to its de-energized origin. Any background info on this concept (good/bad experience)?

Also - are there any inherent probelms / disadvantages with using a permanent magnet plunger (alnico, ceramic, ...) to be able to provide both a pull and return push force by reversing the current? Any experience with this would be helpful.

thanks
Ron

 

[MintJulep]

Do you mean push/pull without a spring at all?

In the event of a loss of power, the valve's position will be indeterminate. Depending on the application, that may or may not present a problem.

Also, the valve become polarity sensitive. Wiring errors will cause problems.

 

[rmetzger]

"Do you mean push/pull without a spring at all?" Yes - at least to provide the force for the operation - I'll still use a spring to set the default de-energized state.

Can you elaborate on the polarity sensitive issue?

thanks,
Ron

 

[MintJulep]

If you design the valve as:

Terminal 1 positive and Terminal 2 ground = "push"

and

Terminal 1 ground and terminal 2 positive = "pull"

and the wires get switched, then the valve will operate opposite to what you expect.

 

[rmetzger]

OK, thats what I thought. That shouldn't be a problem as this will only be used in one application.and all the wiring will be done in-house.

thanks

 

[desertfox]

Hi rmetzger

The only thing I would comment on the push/pull solenoid with the spring, is that depending on which direction the plungers moving the magnetic force will either be additive or subtractive with the spring force.

regards desertfox