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    Dieselblend LPG Development- CRD Injector Flow Rate Info Required Archived Message

    Posted by Eddie Zyla on December 2, 2008, 10:47 pm

    Hi all, those of you who've been Uk Autotalk members from it's early days will probably remember my association with the Fueller, i'm now involved in the development of a new product and seek kindly your help with a few technical issues.

    My everyday business is F1 Automotive, based in Bolton, we are Superchips Dealers, with rolling road and specialise in fuel injection repairs to petrol, CRD diesel and LPG systems. We are also installers of all types of LPG systems and have recently been appointed by PRINS LPG of Holland to be their northern training school and centre of excellence.

    The pioneering company requiring your help here is Hybrid Combustion, i am one of 5 involved and the company carries out all it's R&D and testing at the F1 Automotive premises using my dyno and emissions testing facilities.

    We believe we are developing the worlds first CRD multipoint sequential and closed-loop Dieselblend LPG system. Existing systems use iether historic mixers or some inject vapor or liquid LPG into the inlet manifold, both being known as fumigation systems.The drawback with this type of system is that LPG cannot be totally shut off between gearchanges or indeed on overun therefore creating huge amounts of hydrocarbons leading to failure of Euro 3,4 and 5 emissions bag testing at Millbrook or Mira. Also, these types of systems are unable to measure how much diesel is actually being injected into the engine and therefore use a seperate MAP to calculate how much, but not when,to deliver LPG. These installer or manufacturer based MAP calculations are often based on MAF, TPS, BOOST and ENGINE SPEED, but NOT on precise quantity and TIMING of the diesel injected.

    Our system works in a unique and patented way, firstly, we intercept the very high voltage CRD injector wiring from each injector in sequential firing order. Secondly, by measuring the current through this 2000 volt to ground insulated circuit we can measure the precise diesel injector opening time, even the very short primary pulses prior to the main pulses taking place. We now also take the variable voltage from the high pressure common rail and by adding together these two values and using complex arithmatic with a variable offset value we can output a useable control signal.

    If you were to scope this signal you would see what appears to be a conventional - non current limited- 12 volt to ground petrol injector signal. We've initially output this from a 2ms to 10ms range, however, this can soon be increased when operating with very large capacity HGV engines and when bigger LPG opening times are required. We've based our initial calculations on the LPG system never exceeding 30% of the engines fuel requirement, even when fuelling on a replacement fuel strategy.

    Due to the systems unique ability to quantify and measure the precise amount of diesel fuel injected we then sequentially only inject between 8% and 12% LPG vapor behind the engines inlet valves. The theory for such a small amount of secondary fuel being injected is to try to achieve homogeonous combustion whereby upto 98% of the often difficult to ignite diesel/air-fuel mixture is burnt and therefore improving engine power and emissions.

    During normal running we inject the LPG at approx' 380 degrees ATDC (of the combustion stroke), this ensures that no gas enters the cylinder during exhaust and inlet valve overlap therefore minimising tailpipe hydrocarbons. Having this precise fuel timing control may allow future diesel particle filter regeneration by injecting some unburnt LPG into the exhaust under chosen conditions whilst the exhaust valves are still open.

    We have in the last few months successfully converted several CRD vehicles to run on this dieselblend system, although amazing dyno power increases also NOX and PM's reduction have been achieved we need further R&D time to record more results. Initial results also show approximately 20% BHP and torque increases whilst fuel savings vary anywhere between 15% to 25%, not brilliant we know, but, huge savings to a haulage contractor.

    Now that i've explained how our system works, can anyone assist us with the following information we require.



    What we need is as much information on CRD injector flow rates, particularly injector flow rate referenced to different common rail pressures. For example, if a diesel injector where to open for 1ms and say at 500 bar deliver "x" amount of diesel then would the delivered quantity be double if the rail pressure doubled to 1000 bar

    Is the injector flow rate linear?. We know for instance that a PRINS LPG injector may have a "dead lift" of say 1.5ms, therefore, at a constant pressure, for the injector to double it's delivered quantity when open for 4ms it would have to be opened for only 6.5ms. At 11.5ms the fuel flow would be 4 times that.

    Looking at the high voltages and current involved with CRD injectors i seem to think there is less "dead lift" involved, but, i also predict there to be a massive difference between what i call normal and the new generation piezo injectors which operate at higher pressures still and yet greatly reduced opening times.

    Without this information we can still complete all our R&D but with it things would progress at a much faster rate


    I'm assuming that the information we desperately need is out there somewhere, can anybody please help. We are more than happy to pay for this information or cover costs.

    And finally, Peter (warman) please dont for one minute think i'm using UK Autotalk to promote this product, it will be several months before we are ready to launch. This is in the interests of the whole motor trade and if successfull can only bring much needed work to the countrys often suffering motor industry.

    Regards Eddie Zyla.

    01204 529529 - landline.

    07958 529529 - mobile


















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