[Diy_efi] CIS EFI via Fuel Pump PWM

[Mike]

At 07:18 PM 10/8/2002 +0100, you wrote:
>Well let us all know, eh?
>    Huw

Sorry, don't understand your query, I'm not doing PWM pump control,
I've raised some observations re factors to take into account
regarding PID control, thats all - nothing to let you know about Huw,

rgds

mike


>----- Original Message -----
From: "Mike" <erazmus at iinet.net.au>
>To: <diy_efi at diy-efi.org>
>Sent: Friday, August 09, 2002 12:43 AM
>Subject: Re: [Diy_efi] CIS EFI via Fuel Pump PWM
>
>
>> At 10:19 PM 7/8/2002 +0100, you wrote:
>> >I'm forgetting nothing, instant in this case is relative to having pump
>near
>> >rail, I just can't see the extra length doing anything.
>>
>> Well if someone knows the spring constant for the pipes/hoses etc
>> Then I'd be interested to see the delta volume from say 30 to 60psi ?
>>
>> Re: Your first comment, it *will* take time to build pressure from
>> idle to WOT - heaps of factors, the rotational intertia of the fuel
>> pump rotor is one reason and re my 1st para above - the other factor
>> is the delta volume of the fuel rail (in total) - a quick check in
>> my lab suggests this is definitely *not* instant ! And is therefore
>> a factor to include in any PID algorithm and an indication of
>> what sort of current you want to dump into a pump from a boost mode
>> SMPS, but of course, empirical evidence aside - I just haven't
>> done a delta volume calc taking into account srping constant of
>> steel - but I *have* done a quick test, looks like anything from
>> 0.1 to 0.2 secs but not sure - I got other more important things
>> to do ;-)
>>
>>
>> rgds
>>
>> mike
>>
>>
>> >    Huw
>> >----- Original Message -----
>> >From: "Mike" <erazmus at iinet.net.au>
>> >To: <diy_efi at diy-efi.org>
>> >Sent: Wednesday, August 07, 2002 12:48 PM
>> >Subject: Re: [Diy_efi] CIS EFI via Fuel Pump PWM
>> >
>> >
>> >> At 11:39 PM 5/8/2002 +0100, you wrote:
>> >> >Erm, how will it take time to build up? Unless a "long" length of
>rubber
>> >> >hose is used, it will be instant.
>> >>
>> >> No - instant is not very likely, what does that mean micro seconds ?
>> >>
>> >> You are forgetting the rotational
>> >> inertia of the pump rotor... and the propensity for the fuel pressure
>> >> regulator to oscillate during a step change in flow/pressure, most
>outlets
>> >> of high pressure fuel pumps have a damper - mostly for the injectors
>> >> but also of value in reducing fuel pressure diaphragm flutter...
>> >>
>> >> rgds
>> >>
>> >> mike
>> >>
>> >>
>> >>
>> >>
>> >>  There might be an issue with dynamic flow,
>> >> >but given adequately sized solid tubing I would suggest this would be
>> >> >minimal.
>> >> >    Huw
>> >> >----- Original Message -----
>> >> >From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
>> >> >To: <diy_efi at diy-efi.org>
>> >> >Sent: Monday, August 05, 2002 1:44 AM
>> >> >Subject: Re: [Diy_efi] CIS EFI via Fuel Pump PWM
>> >> >
>> >> >
>> >> >> ARKK tapped away at the keyboard with:
>> >> >>
>> >> >> > I asked this a week or two ago. I'm still hoping someone will ut
>in
>> >> >> > their two cents about the viability.
>> >> >>
>> >> >> > The idea was that CIS injectors could adequately be controlled via
>> >> >> > fuel pump modulation for pressure control.
>> >> >>
>> >> >> Unlikely to be successful unless the pump is quite close to the
>> >> >> injector. System delays will be the source of control problems;
>> >> >> it'll take a while for the pressure to build up over a couple of
>> >> >> metres of fuel line.
>> >> >>
>> >> >> What will you do to _reduce_ the pressure when load reduces?
>> >> >>
>> >> >> --
>> >> >> /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
>> >> >> \ /  ASCII ribbon campaign | I'm a .signature virus!
>> >> >>  X   against HTML mail     | Copy me into your ~/.signature
>> >> >> / \  and postings          | to help me spread!
>> >> >>
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