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  • Duel fuel injectors

    While researching for my senior design project I found some patents for duel fuel injectors that permit the use of gasoline and CNG or any other gaseous fuel in engines. I have not been able to find out if anyone is actually producing such an injector as this. Has anyone ever seen or used an injector that allows for the use of both fuels in one injector? The patents I looked at were for injectors that would replace the stock injectors in the engine.

  • #2
    Re: Duel fuel injectors

    I have set up engines to run with both fuels (gasoline or cng), but not with duel fuel injectors. One of the problems I've seen with dual fuel is the optimal compression ratio's for each fuel is different. The result can be a lower power curve when running cng on a engine designed for gasoline. This can probably be minimized by chosing a higher compression ratio gas engine and by controlling the spark advance specifically for each fuel. In my opinion, given the limited availability of cng, the advantage of running on either fuel outweights the loss of power. Also, you may consider getting a copy of NFPA 52. Lots of helpful information, to help do the job right.

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    • #3
      Re: Duel fuel injectors

      flannelman,
      I've heard the injectors in the dedicated Fords and Dodges were actually designed for CNG by Bosch but will work on both liquid (gasoline and alcohol) and gasious fuels.
      I have also seen some info on Bosch bi-fuel systems being developed in Europe, but have never seen one first hand.
      http://www.greencarcongress.com/2005...develops_.html
      Your Friendly Nazi Squirrel Administrator

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      • #4
        Re: Duel fuel injectors

        Gaseous injectors have to be fabricated of materials which allow operation of a dry fuel. This can cause wear and overheating if liquid injectors are used. Plus, gaseous fuel injectors outlet opening is many times larger than liquid injectors which would prevent a suitable spray from being formed in liquid state.

        As for if any have been produced, just having a patent on an item doesnt mean that you have to actually produce one. The US Patent office has a division now that actually previews patent applications for actual feasibility. There are many patents filed for drugs with one molecule change, electronic circuits where one capacitor has been changed from the original design, and many, many, patents for engines that cannot work even though there are patents issued.

        I am not familiar with your research item but I do know that some were issued. I would put the probability of actually finding some that work with any successful life, at lower than finding a chicken in a dentist office. Possible, but more than not unlikely.

        Franz

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        • #5
          Re: Duel fuel injectors

          Thanks for the info. I was looking at a really neat patent that used two different outlets for the gaseous and liquid fuel. I'll dig up the patent number later and post it here. The reason my group is looking at this is because of the limited, or nonexistent, CNG infrastructure in Arkansas. We don't have any CNG filling stations that I know of. What my group wants to do is look at a duel fuel vehicle conversion that will be a stop gap till the infrastructure is in place to support a large population of CNG vehicles. We are looking specifically at the conversion process to see if we can feasibly do it in a way that will meet all legal requirements and be a reliable option for the average consumer here in Arkansas.

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          • #6
            Re: Duel fuel injectors

            Flannelman,
            Yes, you've hit the nail on the head and welcome to the "Chicken and the Egg" side of CNG. You are definately in a good location to help with CNG awareness.
            Little Rock will certainly help "The I-40 Corridor Project", not to mention the I-30 connection to Dallas, and as a gateway to Branson, MO. The westbound 40-30-20-10 route and vice versa will be a great help to the general use of CNG.
            A station at Adams Field and/or UALR would be a welcome site to cross country travellers. The we just need West Memphis and Texarkana and Arkansas is covered.
            Your Friendly Nazi Squirrel Administrator

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            • #7
              Re: Duel fuel injectors

              Howdy,

              Talking about dual fuel injectors, has anyone thought of unifying spark plugs to work at the same time as CNG direct injection nozzles? That way the same hole could be used to retrofit CNG system to existing engines with almost zero modification.

              Just a thought of a village idiot, but what the heck, go ahead and nail me down and I'll come up with twice as crazy ideas... : )

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              • #8
                Re: Duel fuel injectors

                Hewey,
                Not crazy at all. I've been down that path when I was designing a plasma injection system. Now, if I can just figure out how not to burn large holes in the tops of the pistons.

                I'm working on an adaptation of MB diesel common rail piezo/hydraulic injectors that can DI at up to 30,000 psi and fire a spark halo. With a hypereutectic combustion chamber and piston dome it might just work.

                Next crazy idea, a magnatron injector microwave combustion chamber.

                Time to blow the dust off those metallurgy texts. What I really need is some of that special metal foil from Roswell, NM.

                I wonder if Area 51 has an e-commerce site setup yet?
                Your Friendly Nazi Squirrel Administrator

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                • #9
                  Re: Duel fuel injectors

                  Dual fuel injector? Using an injector designed for dry fuels, and assuming that the injector is nothing more than an electronic valve, why not just adjust the rail pressure to get in the ball park for the volume of fuel needed and do the fine tuning of A/F ratio with the injector on time and O2 sensor. The higher the rail pressure, the more fuel that will flow through a specific size hole, (injector) in a given unit of time.

                  I believe this theory will work with a gas or liquid, or with port or direct injection. Just an inlet for each desired fuel in the fuel rail, control each fuel with a soleniod.

                  Maybe this is too simple

                  Larrycng

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                  • #10
                    Re: Duel fuel injectors

                    Larry,
                    I can see maybe CNG through a methanol/alcohol liquid injector of proper size.
                    But liquid through a dry gasious injector would lack atomization and spray direction/pattern. Probably get real bad mileage.
                    We can't start talking about running vaporized gasoline though a gasious injector, because people who work on high mileage vaporized gasoline systems die or disappear mysteriously.
                    Your Friendly Nazi Squirrel Administrator

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                    • #11
                      Re: Duel fuel injectors

                      Hal, true about the liquid fuel.

                      We could just stick with gasious fuel and make it tri-fuel; Lp, Ng, and H2. We could also mix our own HCNG (hythane) with the right controls and sensors; fuel pressure, fuel temperature, and fuel control solenoid, on the fue rail along with a good bit of programing

                      Larrycng

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                      • #12
                        Re: Duel fuel injectors

                        Cnghal, that plasma/microwave stuff went over my understanding. I will not even try to comment anything but I wish you the best of luck with them if you are building something!

                        Larry, how about just using variable ratio of fuels? CNG would be the main fuel and the compression ratio could be set a little higher. Benzine could act as a reserve fuel, and could be used to "dilute" the main fuel = CNG, when the next CNG station is still far away. This way the compression ratio could be tuned more towards the CNG. You could then limp your way back to the CNG station with a light foot, and when the CNG totally runs out, gasoline could just run the heavily retarded engine at 45 mph or so.

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                        • #13
                          Re: Duel fuel injectors

                          Originally posted by larrycng View Post
                          Hal, true about the liquid fuel.

                          We could just stick with gasious fuel and make it tri-fuel; Lp, Ng, and H2. We could also mix our own HCNG (hythane) with the right controls and sensors; fuel pressure, fuel temperature, and fuel control solenoid, on the fue rail along with a good bit of programing

                          Larrycng
                          That's a lot of tanks... and a lot of expense. Better be a really big vehicle, or really small tanks.

                          Can a liquid injector have enough adjustment to pulse length to allow the flow of gasious fuel in sufficient quantities?

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                          • #14
                            Re: Duel fuel injectors

                            You would have to balance flow rate against how fast the injector can operate. I believe CNG and LP could be done without too much problem. Trying to add hydrogen would be the challange since a much larger volume of fuel would be needed -- it could be offset by a bit higher pressure.

                            Tanks? that is what they make pickups or "high cube" vans for

                            As a serious side, a guy, Tia Robinson, ran a '99 Toyota PU on gasoline, CNG and H2, and it didn't do too bad. It was a fumagiation system through the same mixer, regulator, and system components. He ran on which every gas he could get (Had some support from Praxair) or gasoline if all else failed. It went across country on one of the late Dennis Weaver's Drives to Survive.

                            larrycng

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                            • #15
                              Re: Duel fuel injectors

                              Tai is currently on another cross-country promotional trip in an ethanol/cng/hydrogen vehicle.

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