Dual Stage Fuel injectors?
Dual Stage Fuel injectors?
(OP)
Hi, I've been reading this board for awile but this is my first post.
I'm wondering if anyone here knows much about "dual stage" fuel injectors. I'm not talking about using two differnt sized injectors. I have been told that there are new large injectors that flow like a small injector at low rpm's inorder to give good idle and low end response and flow like a large injector at higher rpm's. I haven't been able to find much info on these. I did find one Japanese company, Power Enterprise, that seems to make a dual stage injector for the WRX but thats all I know. Does this type of injector actually exist and if so who makes them?
I'm wondering if anyone here knows much about "dual stage" fuel injectors. I'm not talking about using two differnt sized injectors. I have been told that there are new large injectors that flow like a small injector at low rpm's inorder to give good idle and low end response and flow like a large injector at higher rpm's. I haven't been able to find much info on these. I did find one Japanese company, Power Enterprise, that seems to make a dual stage injector for the WRX but thats all I know. Does this type of injector actually exist and if so who makes them?





RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
Tim
Or using two coils one coil would control a 'limit' stop.
RE: Dual Stage Fuel injectors?
Having two orifices or two solenoid for the fuel injector would increase the size of the injectors. This would cause the intake port and water jacket designs to be more difficult than the conventional design.
I also want to add that for fuel vaporization purposes, it is good to have injector as close as possible to the combustion chamber thus giving a good part load response, performance, mixture and emissions. Not to mention the benefits during cold winter in Sweden.
On the other hand, for WOT at very engine revolution, I would like to place the fuel injector far away from the combustion chamber thus giving good fuel vaporization.
Given a choice between two stage injector and two injectors (one near and one away from the combustion chamber), I would rather choose two injectors.
AO
RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
For big race engine, the injector sizing is a bit tricky. Still there are ways around it, for example, we can choose the suitable pressure regulator, we can increase the idling speed, etc.
The F1 engine for example can rev up to 19000rpm, still, it is the same injectors that inject fuel at idle. Of course the idle speed is not low, but they dont really care about the idle emission and fuel consumptions.
On the other hand, the new sport bikes have dual injectors for each cylinders to enable them to have high output while at the same time low idling speed and good idle fuel consumption and emissions.
Once again, there are ways to avoid having to use dual stage injector.
AP
RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
Interesting, can you check for me whether the variation in voltage is controlling the built in pressure regulator or the electric motor itself? Nowadays, returnless fuel pump integrates the pressure regulator within the same housing.
The idea of using variable controlled fuel pressure regulator is not new. It is hard to control the electric motor itself because it depends a lot on factor like electric motor aging, battery performance,etc.
On the other hand, if the voltage controls the pressure regulator at certain pressure 3.5, 4 or 5 bars, it will be much easier to control the fuel injector flow.
AO
RE: Dual Stage Fuel injectors?
With regard to fuel injectors intended for racing use, they should be low impedance, fast response models. Injectors originally designed for turbocharged engines have way better low end linearity.
RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
Here is an interesting addition that I am asking back. What about injectors that are cam driven (similar to large CAT or Detroit Diesel engines) and use a varable cam system to deliver the fuel you want relative to engine speed. It is possible that you would have incorporated a variable cam for the valves so why not add a few lobes for the injectors. Granted it will put more stress on the cam , lifters, drive gears etc...which would add to the cost...Just some additional thoughts
I started rambling but I still think my idea is an intersting one. Anyhow i'll look for some info.
RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
I also found an article on make your own at
http://www.autospeed.com/cms/A_1522/article.html and two follow up articles, but schematic is available at small charge. My question is does limiting the voltage cause any loss of motor life?
RE: Dual Stage Fuel injectors?
DC electric motors don't respond too well to being run at voltages much below their design condition.
Battery voltages in cars are often pulled down by electrical load, battery condition and operating conditions. Starting voltages in cold climates can be down to 8V, with idle voltages down to 10 or so at idle with lights, heaters, etc. on. The result is that the motor performance is not linear with voltage changes. Different samples of the same pump will perform in a different way at the same reduced voltage.
I have worked on the development of fuel systems using pulse width control of the electric fuel pump, in closed loop with a fuel pressure sensor plus system calibration control which can either maintain a fuel pressure drop across the injector regardless of engine load, or can vary the pressure depending upon other sensed conditions.
The Walbro pump mentioned will perform well in a system with PWM and pressure sensor feedback. The pump is a positive displacement type (gerotor design) similar to Pierburg pumps I have experienced in high power applications.
Another US Ford which uses PWM fuel pump control is the Lincoln Towncar (not sure if the names right, but it was coded DEW98 by Ford) - the associated 'S' Type Jaguar uses a similar electrical control system.
As already noted - pump noise (always a problem with positive displacement pumps) is better controlled.
Another informative web site ref PWM is
http://www.4qdtec.com/pwm-01.html
RE: Dual Stage Fuel injectors?
My understanding is that these injectors have a relatively slow opening rate. As a result at very low duty cycles they act like smaller injectors than they really are because then never have time to fully open and get to max flow rate. As the duty cycle gets higher they suddenly seem to flow more fuel as the finally are getting enough pulse width to completely open.
It makes tuning at the low rpm of the fuel map somewhat complicated because you have to anticipate where this threshold of full flow will be the dominate mode of operation. Folks would add x percent to the fuel at low rpms and get x + y fuel and they couldn't figure out why. I think the original "dual stage hypothesis" has entered the early stages of an urban legend.
Larry
RE: Dual Stage Fuel injectors?
A lot of aftermarket systems also jack up the fuel pressure to extend the high end fuel flow rate.
RE: Dual Stage Fuel injectors?
RE: Dual Stage Fuel injectors?
It had dual coils and a molded in circuit, one coil a low impedance one optimized for opening speed and the other counter wound coil supplied a high impedance hold. Part of the strategy was to reduce the decay time to reduce the delayed start of armature close flight time. It would open under .4ms and close at about .5 or less. Another issue is opening and closing bounce that the cng design minimised by using low valve mass and lots of spring load aside from other sophisticated yet simple design features. It was proposed for a low smog application but would have been great for racing apps due to the high 300+lb/hr flow capability at 6000rpm.
For more dynamic forget solenoids and actuate the valve with terfenol and the turndown ratio will exceed 100:1
RE: Dual Stage Fuel injectors?
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The key inventor operated a set of dual coil injectors for a period of years without problems. This allow a low cost saturated switch type ecu driver equipped engine to use a fuel injector with best of breed peak and hold performance with exceptional demonstrably superb voltage and temperature compensation.