Diesel high pressure injection pump

[pizzaice]

Hi there,

I want to drive a delphi diesel pump of a Ford "Puma" 2.0 TDCI with an electric motor and I am not sure what power/speed I should choose. I can't find information on this pump on the net in terms of optimum speed and the sort of power this thing requires.
Am I right in assuming that the pressure the pump is creating (according to some sources this one does 1300bar) stays constant between idle speed and max rpm of the engine? How is this regulated? If this is the case, it would be quite suitable as I could keep the motor that is running the pump (on the bench I am setting up) running at say 1000 rpm constantly.

I would be glad if someone could give me some advice on this.

Best regards,

Chris

 

[BrianPetersen]

I don't know about that particular engine, but most common-rail high-pressure pumps are designed to be driven through the crankshaft/camshaft drive mechanism. Some of them are off the end of the camshaft (half crankshaft speed), others are independently driven by the timing belt or chain. Half crankshaft speed is rather normal.

Common-rail injection systems normally have fixed-displacement pumps and an external regulator, which may be electronically controlled. The regulator may be part of the common-rail pump housing, or it may be external. It should be possible to figure this out by looking at your pump.

 

[SonyAD]

Don't know what the pump does but the pressure in the rail is not constant. It varies between idle and full load and rpm from 350 to 1350 or from 250 bar to 1,600 bar:

http://www.peugeot.com.au/PEUGEOT/AU/clientdocs/asp/minisites/hdi/technical.pdf

 

[PJGD]

Chris,

If you intend to run at the rated 1600 bar pressure, you will need a 5kW motor which runs (under load) at ~2000 rev/min. 1000 rev/min is too slow; you will trash the pump at that speed and at high pressure. Be sure to only use well-filtered fuel with good lubricity (use the original vehicle fuel filter). Cleanliness is everything.

There is a solenoid controlled Inlet Metering Valve that controls pump displacement, and is used to control the rail pressure via a feed-back control loop. You will need to build a PID control loop using rail pressure as feedback with desired pressure as the target.

PJGD

 

[MikeHalloran]

I'm morbidly curious about why you'd want to run a Diesel pump attached to anything other than a Diesel engine..



Mike Halloran
Pembroke Pines, FL, USA

 

[SomptingGuy]

Yeah, me too. Those things are lethal.

- Steve

 

[SonyAD]

I think he wants to make a water jet cutting machine.

 

[pizzaice]

Thanks for your input. Sorry, I am in europe, therefore my late reply.

First of all - I won't use the pump for running anything else than a diesel engine. However, it will be a Ricardo Hydra research engine and I do not want to drive it directly of it to get as clear results as possible. I am a junior researcher and therefore ask 'silly' questions in this forum

Back to topic:
Brian is right, this pump is normally chain driven off the crankshaft. Gear ratio is approximately 2:1 - which would give a max pump speed of appr 2250rpm (assuming 4500rpm max diesel engine speed).
However, what is still unclear wether it would damage the pump if I constantly run it at this speed. If so, I would probably look at using a DC motor (with control) and variable speed. Unfortunately I was not successful in finding much literature about how such pumps work - any hints appreciated!

The point that SonyAD brought in, is only of limited use as they say: "The internal pressure can vary between 250 bar and 1,600 bar in the 1.6-litre version and 1,650 bar
in the 2.0-litre and 2.7-litre versions depending on demand from the engine management software,
as a function of the speed and engine load."
It clearly states that the ECU is managing the fuel pressure and it is not only depending on engine speed but also on load. Followingly this does not imply that the engine speed is directly related to the pressure that is produced, as this could still be regulated by a valve etc.

Thanks PJGD for your idea of the power such a pump takes. Sounds like a lot - do you have any sort of physical argumentation behind that or is it just an experience value?
Would you mind expanding your second argument? So this would involve a proper controller that controls this valve? - this would mean that the pressure is directly proportional to shaft speed, right?

Thanks guys!!

 

[SomptingGuy]

Chris,

Just out of interest, where are you running this Hydra?

- Steve

 

[pizzaice]

In Brighton

Regards,
Chris

 

[SonyAD]

I believe the injection pump is spun by the timing belt on TDCi engines. It is on my own 2.0 HDi.

 

[PJGD]

Chris,

1) I speak from (highly frustrating) experience, having recently been involved in commissioning two such single cylinder research engines.

In terms of pump drive power, the bare calculations indicate ~5 kW (for a 4-cylinder TDI engine, but somewhat less for a SCRE), but we went with some margin and arranged direct drive from a 7.5 kW Rockwell Automation AC motor, type E02623-A-A001.

2) The whole point of common rail is that you can control injection rate (and thus spray penetration and momentum) through control of rail pressure. The optimum penetration varies as a function of several factors such as boost pressure, effective compression ratio, engine load etc, thus you need the freedom to select the right rail pressure across the speed & load map to get the best calibration. For combustion research, you need independent control of rail pressure, hence the need for a PID controller on the IMV. The motor can run at a constant 2K rev/min while you adjust the pressure between 250 and 1600 bar. We are successfully using a Drivven controller:

http://www.drivven.com/Products.htm

PJGD