Increase the Life of You Oil Accumulator Valve
09-09-2015, 06:11 PM
#1
Drifting
Thread Starter
Increase the Life of You Oil Accumulator Valve
Not mentioning any brand names but I've been installing a hydraulic accumulator on my oil system. Knowing a little about electronics and hearing everyone warn against using an LED to indicate when the valve opened, I decided to take a look at the back EMF coming off the solenoid. Sure enough, it maxed out my scope at >300v(negative)! I put a 1N4007 diode across the solenoid and it clamps the EMF to the diodes forward voltage as expected.
Not only will cleaning up the EMF let you use an LED indicator but it will protect the pressure switch as well as prevent possible break down of the solenoid coil insulation (can develop pin holes from the voltage spikes).
I'm going to use something larger than the 1N4007 only because diodes are so cheap that I might as well go bigger.
If you want to increase the longevity of your electronic valve you might want to add one! I passed the info on to an accumulator manufacturer so who knows, maybe they'll come that way in the future.
Here are some scope traces:
1: Single trigger of the solenoid showing large voltage spike
2: Same as 1 but with the diode
3: Multiple triggers, lots of voltage spikes
4: Multiple with diode
Not only will cleaning up the EMF let you use an LED indicator but it will protect the pressure switch as well as prevent possible break down of the solenoid coil insulation (can develop pin holes from the voltage spikes).
I'm going to use something larger than the 1N4007 only because diodes are so cheap that I might as well go bigger.
If you want to increase the longevity of your electronic valve you might want to add one! I passed the info on to an accumulator manufacturer so who knows, maybe they'll come that way in the future.
Here are some scope traces:
1: Single trigger of the solenoid showing large voltage spike
2: Same as 1 but with the diode
3: Multiple triggers, lots of voltage spikes
4: Multiple with diode
09-10-2015, 07:52 AM
#4
Safety Car
Not mentioning any brand names but I've been installing a hydraulic accumulator on my oil system. Knowing a little about electronics and hearing everyone warn against using an LED to indicate when the valve opened, I decided to take a look at the back EMF coming off the solenoid. Sure enough, it maxed out my scope at >300v(negative)! I put a 1N4007 diode across the solenoid and it clamps the EMF to the diodes forward voltage as expected.
Not only will cleaning up the EMF let you use an LED indicator but it will protect the pressure switch as well as prevent possible break down of the solenoid coil insulation (can develop pin holes from the voltage spikes).
I'm going to use something larger than the 1N4007 only because diodes are so cheap that I might as well go bigger.
If you want to increase the longevity of your electronic valve you might want to add one! I passed the info on to an accumulator manufacturer so who knows, maybe they'll come that way in the future.
Here are some scope traces:
1: Single trigger of the solenoid showing large voltage spike
2: Same as 1 but with the diode
3: Multiple triggers, lots of voltage spikes
4: Multiple with diode
Not only will cleaning up the EMF let you use an LED indicator but it will protect the pressure switch as well as prevent possible break down of the solenoid coil insulation (can develop pin holes from the voltage spikes).
I'm going to use something larger than the 1N4007 only because diodes are so cheap that I might as well go bigger.
If you want to increase the longevity of your electronic valve you might want to add one! I passed the info on to an accumulator manufacturer so who knows, maybe they'll come that way in the future.
Here are some scope traces:
1: Single trigger of the solenoid showing large voltage spike
2: Same as 1 but with the diode
3: Multiple triggers, lots of voltage spikes
4: Multiple with diode
09-10-2015, 04:25 PM
#5
Drifting
Thread Starter
When you turn off the solenoid, the magnetic field collapses and induces a current in the solenoid coil (just like an ignition coil). The diode provides a path for that negative pulse to flow back through the solenoid.
An RC snubber could also be used as well as several other techniques. I prefer the diode (cheap and robust). The 1N4007 has a 1000v PIV and is dirt cheap. But any protection is better than letting the pressure switch arc from the spike!
An RC snubber could also be used as well as several other techniques. I prefer the diode (cheap and robust). The 1N4007 has a 1000v PIV and is dirt cheap. But any protection is better than letting the pressure switch arc from the spike!
