I am late to this discussion and am only here to offer a little info on PWM water delivery in the ag sector. Case IH uses it on their patriot sprayers. I'll look up the name. I'm on the iPhone and it's a bit clunky. It might give you some ideas.

 

Any progress ZX? Wish you were closer so I could help you out. I'm very interested to see the results for my build.

 

Sorry nothing to report yet. Reason being I got back to work on the LS1 Miata and made some good progress on that, but not this. I'm also really interested in the results so don't worry I'll have something as soon as I can.

 

Anyone knows a formula to calculate flow out of multiple nozzles?

E.g, four 70cc(1gph) nozzles, driven by a 150 psi pump, there is a checkvalve, too.

I am in the process of converting an AEM progressive kit into a port injection setup. Best I can find are the 70cc nozzles.
Instead of fabbing an aluminum manifold, I'll do what ZX-Tex has done, and go with the three Y connectors. Much simpler, less volume.
I also have a pretty sensitive knock warning system. (knockgauge.eu) Works incredibly well. I am planning on relying on that for system problem detection till I can come up with an alternative.

 

Try this web site for info. I don't have enough info to figure it for you. I would need to know what pressure your nozzles are rated for and how much pressure you will be running. I have a spreadsheet for this, but it is on my computer that my power supply died on this saturday.

TeeJet - Spray Pressure Information

Just multiply the flow amount by the number of nozzles. This is one thing I actually deal with as a farmer... The flow pressure will be the line pressure minus the pressure inside the manifold. I am assuming you are not using a fuel pressure regulator for the WI that references the manifold pressure.

If that is too confusing you can find charts on that web site that will give you flow at various pressures for certain nozzles, but different type nozzles are rated at different pressures. Here is an example.

http://www.teejet.com/media/cfefeb5c...LoRes_p020.pdf

The TP80015 is rated at .15 GPH (yours is .166) at 40 PSI. You can use that chart to get a rough idea if your nozzle is also rated at 40 PSI. They also have metric charts on this site and there are european manufacturers.

Hope that helps some.

 

Thanks.

Using the formula you have provided, once the boost pressure is factored in, I end up with 327.6 cc/min. total amount for all 4 nozzles.

Works well for me.

327.6 cc/min = 5.2 gph


Should I subtract the check valve cracking value, too?
In that case, the 5.2 gph flow rate shall decrease further, of course.

What's an AEM check valve rated at?

 

The pressure for flow calculations needs to be taken at the nozzle with the system running. The ag sector has all kinds of controller options for these applications. Most are pressure based controllers and are tied to speed, but there is no reason they could not be tied to an RPM signal or MAP reference. However finding a flow meter for such a small amount might be difficult. Raven makes a chemical injection system that might be able to do it. It is called the "Sidekick" I think.

 

UPDATE:

I have the Aquamist HSV and the PWM control working. It turns out that triggering the HSV using the Adaptronic without the engine running was very easy

As mentioned before the Adaptronic has outputs that are easily reconfigurable in the interface software. All I did was set the HSV output to be PWM (0% to 100%) in response to the throttle position sensor (TPS). It worked very well. Moving the throttle varied the duty cycle on the HSV. I set everything up in the engine bay, including the laptop, so all of it was right in front of me. I watched the on-screen gauges in the Adaptronic interface to keep track of what the DC was. So if I wanted to do it on the benchtop I could do this though I would have to pull the ECU out of the car and wire in a spare TPS. Not too bad I suppose.

As far as how the HSV WI setup works, after playing around with it for a few minutes here is what I have seen so far:
- I am having trouble with one of the four WI nozzles. It looks like there is debris in the nozzle and I cannot get it cleaned out.
- I really think it could use an accumulator between the pump and the HSV. The pressure fluctuation from the pump is problematic for maintaining atomization at lower duty cycles. I think an accumulator would help this out.
- The accumulator effect in the hoses downstream of the HSV is negligible.
- There is definitely a minimum DC at which the mist is well atomized. I am wondering if it would be worthwhile to go to smaller nozzles and up the pressure at the pump.
- Distribution between the nozzles looks good visually.

 

UPDATE:

The nozzles were not clogged. I had a blockage problem with a fitting which is now fixed.

Rather than mess with the accumulator I took a different tact. I sold the standard 150 psi pump (that DO included with their kits a while back) and bought the 250 psi pump. Not so much for the increased pressure, but for better flow. The 250 psi pump has an internal bypass pressure regulator instead of a switch regulator like the 150 psi pump. So the 250 psi pump once powered up runs continuously instead of pulsing on and off like the 150 psi pump. I tested it tonight with the HSV and the flow is a whole lot smoother at lower duty cycles. Much better.

The two pumps can be seen here. Notice how the 150 psi (and 220 psi) pumps have the wires that run to the head of the pump unit. This is for the pressure regulating interrupt switch. Also notice that the 250 psi pump does not have those wires.

BTW the pump difference is probably not a big deal for the on-off setups (no HSV, full flow) because the flow is steady even with the 150 psi pump. I only switched because of the HSV setup. And even the 150 psi pump could be made to work with the HSV if an accumulator was used between the pump outlet and the HSV inlet.

I have been thinking about how to make some kind of video of the injectors running but it might be a tricky thing to capture on a standard camcorder. I was wondering if some benign fluorescent dye in the water and a blacklight would help

 

Very cool.

A strobe light, synced to the NTSC framerate. Maybe even a timing gun, controlled by the ECU, with the RPM set to a fixed value.

 

Interesting. I had not considered that.

 

OK Joe (or another EE) please check me here. This is a partial cross-post (italic font) from the Adaptronic board; I know not everyone goes over there. See the part towards the end (in bold) about using a SSR to tap off of the fuel injector circuit.
http://adaptronic.com.au/forum/index...sg7444#msg7444

FlyingGrape is right. The Aquamist HSV is fast. In fact I ran it at 200 Hz and it worked fine. Even at 8000 RPM (for sequential mode on a 4-cylinder) the fuel injectors are only firing at ~66 Hz if my math is right.

Slides go for it but I am not going to implement a water/lubricant emulsion system for the WI so that I can use a fuel injector. No thanks.

Cobber that is an interesting idea. Hmmm... The Aquamist HSV has the same resistance as a high impedance injector so it can be driven by an injector circuit. I am not sure if the extra load would impact the other injector in the circuit if I tapped straight off. I suppose I could isolate it with an IGBT or something like that.

I wonder if there is a setting in the Adaptronic that allows an aux output to mimic whatever the injector drives are doing. I do not remember seeing it in the manual or in WARI. That would take care of it right there with a relay to set the threshold like you suggested. There is a two-stage injection setup but I think that still requires the second map correct? I RTFMed but I am not getting it yet on exactly how to set up two-stage injection.

EDIT: OK more on Cobber's suggestion. I could use an IGBT aka solid state relay (SSR) like this one.
http://www.grainger.com/Grainger/items/1DTT2?Pid=search
- The input side of the SSR would be driven by tapping off of one of the injector drive outputs. The output side of the SSR would drive the HSV. That way the SSR/HSV would put a negligible load on the injector drive circuit.
- On the output side of the SSR, instead of going straight to ground, it could be connected to one of the Aux outputs. The aux output could be set for on-off (not PWM) based on say MAP. That way, the SSR does not pulse the HSV unless the MAP threshold has been reached. In fact this could be done on the input side of the SSR for that matter.

IT COULD WORK!
Anyone see any pitfalls here? Before anyone asks, the SSR is plenty fast enough. It changes state in 0.1 ms.

Pros:
- The HSV would automatically follow whatever the injectors are doing, and pulse at the same frequency. Plus a minimum threshold can be set.
- No need to tie up the second fueling map
- Changes in the fuel curve are automatically followed by the injector.
Cons:
- Unless I am running the injectors at 100% DC (bad idea) the HSV will never reach 100% DC. That kind of sucks actually, since the upper part of the HSV DC is where it is the most useful. So I lose range at the bottom from minimum atomization pressure, and range at the top due to max injector DC.
- The WI and FI are not independently adjustable.

 

Use a 60V 20A or so MOSFET, not an IGBT.

 

I might be using IGBT incorrectly. According to the manufacturer of that SSR I linked to above it is a FET?
http://www.crydom.com/en/Products/Ca...ard_output.pdf
I'm open to suggestion. I know little about SSRs.

EDIT: Maybe this one? According to the specs it is a MOSFET. More expensive, but can handle 12V DC inputs, and has better packaging.
http://www.grainger.com/Grainger/items/1EGK7?Pid=search

 

Yeah, at 8,000 RPM you are seeing ~133 revs per second, or ~66 cycles per second. So the injector frequency would be ~66 Hz for sully sequential, or ~133 Hz for a banked system with two squirts per cycle.

The SSR won't work. If you look at the datasheet for it, the rated turn-on and turn-off times are way too slow.

However, you can easily construct a circuit to mirror the main injectors. All you really need is a large transistor and a few supporting elements, and then a means of gating the control system on and off.

Here's a quick-n-dirty sketch of what I've got in mind. It's not complete, but it conveys the basic idea.

You put a positive voltage on the "ENABLE" line to turn the circuit on. That allows +12 to flow through Q1 into the second.

When the injector line is "off", the injector wire will be floating up to +12, and that'll hold Q2 off. When the ECU wants to fire an injector, it grounds the injector wire. That will allow Q2 to turn on and conduct through the HSV to ground.

Q3 and its related hardware is a flyback damping circuit which I've shamelessly stolen from B&G's copyrighted schematics for the Megasquirt.

I should probably move Q1 out of the main current path and into Q2's control path, but you get the basic idea.



EDIT looks like I missed some conversation while I was drawing. What, no love for BJTs, Jason?

 

Yeah sorry about that edit

I cannot find out if that other MOSFET I pointed to is fast enough. For some reason that spec is not listed by Grainger or anyone else, and I cannot find Dayton's web site (if there is one).

 

MOSFETs are waaaaaaaaaaaaaaaay faster than IGBTs.
We're talking MHz vs kHz.

Joe your circuit needs diodes added to prevent reverse biasing of the BE junctions... depending if those ECU outputs are pull up and down or one way only.
MOSFETs are easier to drive than BJTs and usually result in lower parts count circuits.
AND when driving solenoids some of the automotive types have Drain avalanche ratings that makes their flyback voltage clamping built in.
I am agnostic and I will choose a BJT or MOSFET as needed.

 

UPDATE:

OK I have it all in the car and working, even tried it out on a dyno. Some things to report.

- For now I am just using the second fuel map on the Adaptronic to control the HSV. Works great. I'll mess with the other scheme later.

- It seems to only give good atomization at ~60% duty cycle. Below that and the mist becomes more like a spray, then eventually a weak stream.

- I think four of the 2 GPH nozzles is too much. I saw a huge power drop on the dyno when all else was equal and all I did was turn on the water injection. There was about a 15-20% drop at peak horsepower*. This is with 0 deg washer fluid (no detergents) which I believe is about 20% meth. I think it is just too much water/meth, more than twice what the DO calculator calls for. Since I do not have as much usable range as I had hoped for, I cannot run the nozzles at low duty cycles to compensate for their size, which was the plan. They do not have nearly as broad a range as I had hoped.

- With 4 2GPH nozzles, the washer reservoir empties FAST.

- Because of all of the above, I am going to try four 1 gpm nozzles next. Because the nozzles are smaller I should get a broader range of flow control while maintaining good atomization. Also the peak flow (100% DC) will be less, not so much overkill.

- Also, to test out the effect of the hoses post-HSV, I ordered some very thick wall nylon tubing that I am going to try in place of the DO tubing to see if it broadens the usable range. It has a 0.050" thick wall, much thicker than the DO tubing. This should answer the question about whether wall stretch is a significant accumulator.

*Keep in mind on the above power loss, is that the WI is there on my install to provide additional knock margin. I tuned the car without the WI, and added the WI on top of that, without advancing timing or leaning the mixture. That way, if the WI fails, there is less risk of engine damage. If I had advanced timing and reduced AFR with the WI running, I am sure I could have gained back the power and then some.

 

OK good stuff to report...

- Switching to the 1 gpm valves really worked out well. The usable duty cycle range is now from 30%-100% which is wider than it was before (60%-100%).
- At 100 Hz modulation frequency the minimum duty cycle at which I would consider the atomization adequate was about 30%. When I dropped the DC to 50 Hz, the minimum duty cycle dropped to 17%. Interesting. Although I am still using 100 Hz since it pulses faster than the intake cycling rate at 7500 RPM.
- Switching from thin wall hoses to thick wall hoses made no difference in terms of the minimum duty cycle at which atomization was adequate. So, this indicates that the accumulator effect from hose wall stretch is negligible, at least at 100 Hz PWM frequency.
- The threshold between good atomization and bad atomization was very narrow, only about 2% DC. At the threshold, a very small change in DC brings a large change in atomization quality.

Here are some pictures of what the atomization looked like with the four 1 GPM nozzles. The first shows the atomization at 27% DC, 100Hz. The second shows the atomization at 30%, 100Hz. The images are large but they show more detail. At 27% the droplets are larger and are scattering radially all around the nozzles. At 30% they are much smaller and are being carried off by the wind (away from the camera).

 

Looks great!