Single Cylinder Injection Timing Control

oilburner · Post by **oilburner** » Tue Jul 22, 2008 1:52 am

Hatz has been sitting on a patent for a timing control solution on its single cylinder engines since 2000. It is a modification of the existing pump plunger design. AFAIK there are no other changes. This isn't a new concept - Bendix incorporated a similar solution, a second helix (groove) at the top of the plunger of its F series pumps, directly above the idle end of the normal helix - this was over 40 years ago. The Hatz patent was issued on July 4th, 2000. You can view the patent and pictures here:

http://www.google.com/patents?id=1jADAA ... dq=6082335

Timing control would result in less emissions, less noise, smooth idle, improved performance throughout the rpm range, and significantly reduce smoke, basically fixing everything that's wrong with the one lungers.

There several other patents covering much the same solution, appearing to differ in the design of the slot, helix, etc. Click on the list of related patents on the left of the webpage above to see other designs.

Looking at a picture of the plunger in a Launtop injector pump, the Yanmars and clones could probably benefit from this also.

Cockney Bob · Post by **Cockney Bob** » Tue Jul 22, 2008 12:51 pm

Looks good where do I get one for my smokey Greeves.
Bob

oldbmw · Post by **oldbmw** » Wed Jul 23, 2008 10:43 pm

The lack of variable pump timing is the single biggest problem of using industrial engines for road use in my opinion. If this can be solved we are on teh way to a much more refined product.

oilburner · Post by **oilburner** » Thu Jul 24, 2008 4:31 am

Perhaps it's because of all the patents that no company has been willing to incorporate the change. Of course, one wouldn't think that would be a deterrent for the clone makers

Darren · Post by **Darren** » Thu Jul 24, 2008 5:17 pm

I think that this type of thing will be avoided until emissions legislation makes the use of variable timing a necessity for them to comply.

Post by **Stuart** » Thu Jul 24, 2008 10:11 pm

I think one of these was developed for the new KLR by unique injection. It's still classified apparently. The word rotary was used in connection with it so I guess it must be along the same lines.

oilburner · Post by **oilburner** » Fri Jul 25, 2008 12:02 am

Actually, when the injection pump plunger is manufactured, it would take all of 15 seconds for the CNC operated milling machine to add the extra helix at the top of the plunger, immediately above the existing helix. Below is a picture of the injection pump that should be like the ones used on the Yanmar single and clones. I've circled the pump plunger and the arrow points to the helix groove machined into the plunger.

If I was tinkering with the single cylinder engines, I'd read all the patent info etc. and have a go at modifying a plunger. I'd buy the cheaper Chinese ones as the first few would likely end up as desk ornaments

andrewaust · Post by **andrewaust** » Fri Jul 25, 2008 7:06 am

That is a great invention, I agree! The biggest pain might be solved. Set injection is good for constant set rpms, but a real pain for variable speed engines.

Hopefully it will fit many makes and models.

Cockney Bob · Post by **Cockney Bob** » Fri Jul 25, 2008 7:28 am

Is there any body on this forum with the tools and skilll to make one or some.I would buy one if one were available it appears so simple but I doubt it really is .If it were I am sure it would already be available.
Bob

oilburner · Post by **oilburner** » Tue Jul 29, 2008 9:19 am

Further clarification of the difference in plungers for fixed vs variable start of injection timing.

Below is a picture showing the difference between an injection pump plunger with fixed timing (1st three) and one which has variable timing (4th).

Unless I'm (probably) missing something obvious, it shouldn't be um, rocket science to modify current pump designs to implement this feature.

thundercougarfalconbird · Wed Jul 30, 2008 4:03 am

So who is going to be the first to try modify an exisitng pump plunger?

electronbee · Post by **electronbee** » Thu Aug 21, 2008 2:59 pm

I'll do it if I can find a spare plunger for my current clone.

Is that all that is required, just create that channel in the plunger?

eb

Cockney Bob · Post by **Cockney Bob** » Thu Aug 21, 2008 4:12 pm

I can not believe if it is so simple why are they not available. There must be more to it than that still they said that about the paper clip.
If any one can make one for an indian greaves then I will buy it.
Bob

electronbee · Post by **electronbee** » Thu Aug 21, 2008 6:57 pm

Well, you would have to rebuild the pump at the very least just to install the new plunger.

And, that's after you modify the plunger.

oldbmw · Post by **oldbmw** » Thu Aug 21, 2008 9:25 pm

Maybe something has to drive the curved bit ??? some kind of centrifugal device ??

oilburner · Post by **oilburner** » Fri Aug 22, 2008 2:38 am

I'll try to explain how the plunger works. Here's the picture showing the idle and max throttle setting positions on the additional curved groove to be added to the plunger (plunger on the right). I've also drawn an arrow to show where the new groove would be if the fixed timing plungers were modified (see the top of the second plunger).

Looking at the picture above, the first three plungers show fixed timing.

In the first plunger (bottom of stroke), there are two holes just above the top of the plunger, the hole on the left is the inlet from the fuel tank, the hole on the right is the spill port. Not shown is the outlet connection to the injector which would be at the top.

Note that the plunger rotates *clockwise* to increase throttle setting.

1. Fuel from the tank enters through the port on the left and fills the space on top of the plunger.
2. As the plunger starts to move up, it covers the inlet and spill ports.
3. The plunger continues moving up, pressuring the fuel and forcing it into the injector.
4. Referencing the second plunger, when the plunger nears the top of its stroke, the spill port is uncovered by the curved groove (helix) and the pressure on top of the plunger is released thus ending injection.
5. The amount of fuel delivered is varied by rotating the plunger (opening throttle) which causes the curved groove to uncover the spill port *later* (lower point on the curve) in the plunger stroke.

*No Delivery (third plunger)*
When the plunger is rotated so that the vertical slot is directly facing the spill port (engine stop position) , no fuel is delivered since all fuel immediately goes from the inlet over the top of the plunger, down the slot and out the spill port.

Variable Tming

By putting an additional curved groove on the *top* of the plunger (4th plunger in the picture), during the first part of plunger movement the spill port is still uncovered for a bit. This delays start of injection - in effect retarding the timing. As the plunger is rotated (increase throttle setting) a higher point on the curve will be in line with the spill port, covering it quicker in the plunger stroke, effectively advancing the timing. Follow the arrow on the 4th plunger over to the top of the 2nd plunger to see where the additional curved groove would be cut.

The trick is to figure out how far down the plunger to start cutting the groove (shown as idle in the picture). Further down delays the timing further. Then you have to figure out how steep to make the curve. The right end of the curve is max advance (spill port covered immediately as plunger starts to move up).

It is important to remember that with this method of variable timing, the amount of advance is *directly* proportional to the throttle setting. if you whack the throttle wide open, in effect you also advance the timing to max advance. If you gradually open the throttle, the timing will gradually advance.

Hope this helps. Once you get your head around how the plunger works, the modification is simple to understand. Getting the right curve on the groove might be a bit more challenging

.

oldbmw · Post by **oldbmw** » Fri Aug 22, 2008 8:02 pm

Many thanks.
I understand now. It is a Throttle controlled variable timing, not engine rev related ( although they are usually inter dependant).

This would give much better tickover and cruisng.

one thing that has just occurred to me is that the timing would be retarded coming down hill with throttle closed, and fully advanced when working up through the gears but I dont suppose this would make much difference.

regards

electronbee · Post by **electronbee** » Fri Aug 22, 2008 9:34 pm

Do you think it would be possible to modify the existing plunger and take out the material above the idle line? Or, does that entire "fuel helix" have to be calculated from the start?

eb

oilburner · Post by **oilburner** » Sat Aug 23, 2008 1:23 am

Do you think it would be possible to modify the existing plunger and take out the material above the idle line? Or, does that entire "fuel helix" have to be calculated from the start?

You should be able to modify an existing plunger... I wouldn't be surprised to find out the plungers of clone engines aren't even hardened which would make the job easier.

If the plunger is hardened, you will probably have to make the new groove on a milling machine or similar setup (maybe a Dremel on a sturdy stand and a sturdy vice?) using a grinding wheel. Make sure not to leave any burrs that would score the plunger barrel.

The following procedure should help to get a rough idea as to how much material to grind away at the idle line:

1. Remove the pump plunger and insert a dial indicator on top of the camshaft pump lobe.
2. Rotate the crankshaft to BDC at the end of the intake stroke..
3. Zero the dial indicator.
4. Rotate the engine until the dial indicator just starts to move (start of injection.
5. Note the crankshaft position (degrees BTDC.Actually I suspect this should be close to the factory recommended static timing).
6. Continue to rotate the engine in the normal direction of rotation until it reaches the desired position BTDC for idle timing.
7. Note the dial indicator reading. The reading will be the the distance *down* from the top of the plunger to the *idle* side of the new groove. Look at the existing helix on the bottom of the plunger to determine how deep to make your new "timing" helix.

I hope this makes sense!

Darren · Post by **Darren** » Sat Oct 04, 2008 5:26 pm

All looks good to me.

The only thing is machining the second helix will reduce the amount of time the spill port is covered and thus the delivery duration/amount of fuel injected.

This will be a substantial reduction at low throttle slowly changing to no reduction at high throttle.

I guess that the tick over can be adjusted to negate any issues from lower fuel delivery. But in turn this should be factored into the calculations for determining how steep to machine the helix. Tick over will become a point a bit further around the circumference of the plunger thus calculate timing at this point.

oilburner · Post by **oilburner** » Sat Oct 04, 2008 9:37 pm

Actually, by design the spill port is always *below* the new top helix - affecting only the original lower helix (which controls the end of fuel delivery). You can see this in the second plunger example in the picture, the spill port is even with the top edge of the helix curve.

In the plunger example on the far right, notice that the leading edge of the new top helix (at the end of the arrow titled Idle) is positioned slightly above the leading edge of the lower helix (it looks like 1/4 inch in the picture), meaning the top helix never comes in contact with the spill port. The new top helix affects only the start of fuel delivery and therefore the timing at low speeds.

I hope this helps clear up the confusion. It took me 30 years to figure it out!

DieselBike.net

Single Cylinder Injection Timing Control

Single Cylinder Injection Timing Control

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