duty cycle of solenoid valves? 1

[werdnaid]

Looking at using a NO 3 way valve to shut off the boost signal to a waste gate. Porsche uses one on their 944 turbo to vary the boost as the EEM tells it. Do these valves operate off of straight 12VDC or a pulsed 12V & if so what frequency & duty cycle?

drew

 

[NickB]

Applying 12V will make it switch. Applying a PWM of around 50-100Hz and varying the duty cycle from 0 to 100% will approximate 0 to 100% open or closed.

 

[WGJ]

I think you may find that EGR valves (these days) work on a Pulse Width Modulation frequency typically in the range 150-200 Hz. The duty cycle will be to suit the boost you want/need. I imagine that 50% duty cycle would give you about half the gas flow to a waste gate, depending on the mechanical response of the valve and the gas flow restrictions in the system.

 

[werdnaid]

Thanks for your answers.

I think I am going to use no pulse, just DC to .9 of my boost, then a pulse, ? freq?, with a 50% duty cycle to start cracking waste gate , then off at my boost setting.


Drew

 

[carnage]

that should work alright but if in the future you were to make it fully adjustable you could probibly decrease your spoolup time a little more. the important part is to make the circuit as fast as possible to keep your boost levels from fluctuating.