P Series Bosch pumps

C

Charles

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Or any similar mechanical pump for that matter. I didn't search for an existing thread, so feel free to fry away if one obviously exists...

Otherwise, can someone explain to me how exactly these pumps meter fuel delivery quantity? In my mind I see a plunger riding atop a lifter of some sort, atop a cam lobe. Obviously one per cylinder.

Now what I can't figure out, is an effective way to control displacement when the plunger is being stroked by a fixed geometry camshaft lobe. Is the "lifter" being held at varying distances from the lobe centerline to control stroke or what?

How does the "rack" come into play, and what is it moving?


Thanks.
 
There is a helix on the side of the plunger and the rack turns the plungers simultaneously, thus controlling the amount of fuel injected.
 
I didn't see any mention of how fuel quantity is governed by the pump, and the exploded view doesn't show how it would happen.

I'm assuming the rack is somehow altering the "depth" of the plunger when at "rest" or something along those lines? Is there some kind of "ramp" that each plunger or P&B are attached to that the rack can rotate in order to alter the resting height of the P&B relative to the cam centerline?

Anybody know how they work?


I'm purely quenching curiosity here.
 
LReiff said:
There is a helix on the side of the plunger and the rack turns the plungers simultaneously, thus controlling the amount of fuel injected.
Click to expand...

So the governing is done by altering the distance between the plunger and cam centerline when at rest?

I think the "helix" may be the "ramp" I mentioned a second ago.


Is there a picture anywhere of the P&B, rack and helix all together for viewing?
 
LReiff said:
There is a helix on the side of the plunger and the rack turns the plungers simultaneously, thus controlling the amount of fuel injected.
Click to expand...

See previous post! ^^^ The governor is connected to the rack. The plunger travels in an up & down motion past the fill ports...the helix passes the fill port...if this doesn't explain it find a barrel/plunger assembly so you can fondle it and get a feel of it. LOL
 
LReiff said:
See previous post! ^^^ The governor is connected to the rack. The plunger travels in an up & down motion past the fill ports...the helix passes the fill port...if this doesn't explain it find a barrel/plunger assembly so you can fondle it and get a feel of it. LOL
Click to expand...


Doesn't really explain anything at all conceptually.

Like, how a rack can be connected to plungers that are cycling up and down, or whether or not the fuel is metered by physically altering the stroke of the plungers, or by altering something to do with fill ports.

If the explanation is good, I will understand quickly.
 
So is it a situation where the plunger doesn't move any more fuel than desired, or a situation where it moves full stroke each time, but "spills" excess fuel dependent on some sealing between the port in the plunger and the barrel?

Conceptually I'm asking a very simple question.

I guess I'm now wondering is this "helix" changing the relationship between plunger and cam, physically altering the effective stroke.... or is it allowing a percentage of fuel to be spilled off nullifying a certain amount of the stroke?

Thanks.
 
The rack twists the barrels with raises or lowers the spill port. Once the spill port is covered by the plunger it starts to build pressure and inject fuel.
 
GRotman said:
The rack twists the barrels with raises or lowers the spill port. Once the spill port is covered by the plunger it starts to build pressure and inject fuel.
Click to expand...

Okay, okay, now we're getting somewhere.

So it goes full stroke each and every time, it just renders a certain portion of the stroke void as the fuel is diverted.

Cool.

So does the barrel have slits in it or something? One slot up the side or what?
 
Charles said:
Okay, okay, now we're getting somewhere.

So it goes full stroke each and every time, it just renders a certain portion of the stroke void as the fuel is diverted.

Cool.

So does the barrel have slits in it or something? One slot up the side or what?
Click to expand...

That's the job of the helix in the plunger :bang

Charles, did you even take the time to look at all the pictures in the link that I posted for you?
 
RonA said:
It's magic Charles.
Click to expand...

P7100 is magic? Crud. All along I was thinking only electronics worked off of the magic principle. Are they both magic? If so I'll never figure it out.

I suck at magic. Crud Crud Crud :(
 
Snedge said:
P7100 is magic? Crud. All along I was thinking only electronics worked off of the magic principle. Are they both magic? If so I'll never figure it out.

I suck at magic. Crud Crud Crud :(
Click to expand...

No electronics work off of smoke, because once you let the smoke out of them, they quit working. It's obvious that you can let the smoke out of a P7100 for a long time.
 
paulb said:
No electronics work off of smoke, because once you let the smoke out of them, they quit working. It's obvious that you can let the smoke out of a P7100 for a long time.
Click to expand...

So it's the smoke that's magic?
 
imagine, just take a piston and a cylinder, the piston just goes up and down at a fixed volume. now take and drill a hole about 1/4 the way up the cylinder. now fuel leaks out when the piston drops below the hole and only then. now take and cut a slot starting at the top of the piston down about 3/4 of the way, but this slot has to have twist like that of a drill bit. now envision the piston moving up and down with this slot moving past the hole, the only time fuel gets out is when the slot passes the hole. now to add a little twist. rotate the piston as it moves up and down the cylinder now the slot crosses the hole at different times allowing more or less fuel to bypass thus controlling the amount of fuel. done
 
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