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+--- Thread: Delivery Valve Relief Throttle (/showthread.php?tid=763)
Delivery Valve Relief Throttle - dartrpm - 10-14-2009
I was just doing some light reading on Delivery valves and came across something that interested me.
I have not seen anyone discussing the Relief Throttles that are located in the top of the DV. Here is the except from the FSM:
Note:
To reduce hydrocarbons in exhaust gases, rei ief
throttles are installed in pipe connections of injection
pump.
Relief throttle (2) is a poppet valve (3) with an orifice
of 0.6 mm dia. opening in direction of injection nozzle.
Valve seat (4) is riveted into pipe connection.
The relief throttle allows fuel to pass through freely
in the direction of the injection nozzle. The pressure
wave travelling toward the injection pump from
the injection nozzle is caused by the secondary
pumping action of the needle valve as it closes;
this is attenuated by the relief throttle and prevented
from returning to the injection nozzle where
it would otherwise cause secondary injection. This in
turn would increase the hydrocarbon content of the
exhaust gases.
So if you have timing advanced, would this secondary injection come to late and just increase EGT's?
Just something for the injection guru's to think about.
Scott
RE: Delivery Valve Relief Throttle - winmutt - 10-14-2009
What section is this in?
RE: Delivery Valve Relief Throttle - dartrpm - 10-14-2009
07 1-210 Replacement of pipe connection, delivery valve or copper sealing ring on injection pump
RE: Delivery Valve Relief Throttle - tomnik - 10-14-2009
Hi,
it is killing the reflection wave, created by the sudden closing of the nozzle when the injection is finished. The pressure wave runs back towards the IP and would reflect again towards the nozzle to open it a second time.
The orifice is killing the wave. To allow full fuel flow during injection the relief valve opens in this direction.
Everything that comes after the injection has finished by the IP is too late and will not burn completely.
Tom
RE: Delivery Valve Relief Throttle - dartrpm - 10-14-2009
Do you think this would have an effect on those running AAZ injectors, that basically have two injection points?
(10-14-2009, 03:54 PM)tomnik Hi,
it is killing the reflection wave, created by the sudden closing of the nozzle when the injection is finished. The pressure wave runs back towards the IP and would reflect again towards the nozzle to open it a second time.
The orifice is killing the wave. To allow full fuel flow during injection the relief valve opens in this direction.
Everything that comes after the injection has finished by the IP is too late and will not burn completely.
Tom
RE: Delivery Valve Relief Throttle - tomnik - 10-14-2009
No.
I run the AAZ injectors and have the relief valves in my IP.
The relief valves with the orifice did not make a restriction in fuel flow on the bench (I checked in comparison with open DV holders).
On top I set the injectors to 175 bar pop pressure.
Runs great.
Tom