Challenge

[Oldone]

Well, I have learned that I am trying to make a overly simplified venturi vacuum pump.

 

The problem is--can you create enough air pressure by using the ram air going down the road? The second question--can it be made simple enough?

 

Today is Sunday so my beginning will be Monday.

 

I have really enjoyed the Solar cookers- my second project.

 

I have already begun installing a grid solar system. The first thing I bought was my converter ( capable of grid or independent) hoping to disconnect from the grid eventually. Every 6 months I buy a pair of new panels.

[Rocket Man]

what applications are you looking at? i know that some cars use the venturi effect to create a greater downforce. and chem labs use all manner of gas jet eductors all based on the venturi effect to flash off liquids in distillation.

the higher the vacuum, the harder it gets to make.

[Oldone]

I have two grandsons and they are adamant on some limited touring while camping out on motorcycles. I cannot talk them out of the motorcycles, however I wish them to use a sensible size and not a 115 hp rocket ship for I do not think they can safely handle them. However, the 115 hp rocket ships will produce enough vacuum to power a cruise control whereas the motorcycle I wish for them to use does not. Anywhere from eight to ten is needed and the motorcycle I wish for them to use will only produce three.

 

The only time vacuum is needed is while traveling at speeds above 45 miles an hour. I felt by using a PCV reservoir with check valves that I could attach a tube to the motorcycle and produce enough vacuum to power a cruise control. I feel they are trying to use this cruise control as an excuse but however I have always been able to overcome obstacles by diligence or just by sheer luck and good friends.

 

If I was more computer savvy, I would put up a drawing of what I have come up with so far. I have worked out the reservoir and the check valves, routing and placement of the items and am now trying to work out a sensible yet simple to make tube to produce a vacuum out of PCV.

 

Any thoughts or help would be greatly appreciated.

Thank you

[Spyman]

Simple, Inexpensive, "10¢ Cruise Control", for motorcycles: http://www.ibmwr.org/otech/throttlelock.html

[Oldone]

Simple, Inexpensive, "10¢ Cruise Control", for motorcycles: http://www.ibmwr.org/otech/throttlelock.html

 

Ahhh, for you and me that does just fine, in fact I used an inner tube section in 1958, but not for spoiled grandkids (my fault entirely). They want the real deal that gives gas when hitting a grade plus Mike is really into this ( the owner of the motorcycle we are experimenting with).

 

It also seems that quite a number of people are interested in this also, in fact, I have never seen any thread that I have started before, generate this much interest.

 

The only question is can you generate enough vacuum by using the amount of air passing through a collector at 45 to 75 miles an hour? If you can, then I will find a way to make it -- I think:doh: . I think I will put a URL to this thread into the next post I make over there -- who knows -- some of the guys might find a gold mine over here.

[Rocket Man]

at that sort of speed, you'll find it very difficult to utilise the venturi effect to provide any sort of appreciable vacuum. i'd leave the venturi effect for low pressure, high volume applications.

 

how does the system work? i can't really see any link between vacuum pressures and cruise control.

 

i could probably tell you how to do it digitally with minimal equipment (a servo and a bit of a circuit) but a mechanical one sounds so much more exciting.

[Spyman]

Venturi Flowmeter Calculator: http://www.efunda.com/formulae/smc_fluids/venturi_flowmeter.cfm#calc

[Oldone]

Rocket Man

 

This is going to be a very difficult thing for me because I am a man of very limited formal education, although I do have a lot of practical experience, but alas, I have absolutely no eloquence of speech. Also this post will be typed by Dragon Naturally Speaking (arthritis -- smile).

 

The unit itself is sealed but I can tell you that its senses its speed through both the speedometer and the coil. The vacuum is taken off of the intake beneath the carburetor -- therein lies the problem. The vacuum is put into a reservoir (in our case we had to make two separate reservoir's out of PCV because of space limitations and we put a check valve between the intake and the reservoir, plus putting another check valve between the first and second reservoir. It now has slightly more volume than the original reservoir had but it is a miniscule amount It then goes to the sealed unit and then is routed to the vacuum actuator which is a rod that is attached to a cable that connects to your carburetor throttle actuation. Interesting isn't it? -- snicker

 

On anything above 450 CC's creating this vacuum is absolutely no problem because the Pistons are large enough to produce enough vacuum, however anything beneath that, you are in trouble. I am trying to do this on a 250CC. Now this 250 will do well over a 100 MPH and out accelarate most sport cars with a 240lb man on it. I feel that is more than enough for their first 4 or so endeavors. Another hindrance is the fact there is absolutely no room to add anything because all the space is already taken up on the motorcycle -- there is hardly enough room to put a single buckshot in -- well -- to keep the aesthetic looks of the motorcycle -- Youngun's!

 

I am absolutely amazed that we managed to get the Pro Oiler installed on this motorcycle (another job that could not be done), especially with the volume of oil we managed to get and it is completely out of sight, yet easily accessible. it should go 800 miles before refilling. I absolutely hate reed switches.

 

We have bought the vacuum gauge, all the PCV parts and have threaded the one PCV pipe and adapter so we can have adjustment and see if we can increase the vacuum-that is-if we suceed in developing any in the first place. I have Bee boxes to build and my Bees to work plus I must finsh the new back porch, Oh yes. lets not forget the roof. When you get 75 you seem to tire more easily.

 

 

On another note, while I was making a Bee box I went ahead and made a simple cooker Box 12" Deep, 16"w x16"h and lined it with R16 insulation. I put foil on top of that and put a glass door on. Then I seen some soft 1/2 copper pipe and sanded two length's that made one 8" tight coil and formed the other to 4 back and forth 12" lengths. I then painted the coil with flat black heat resistant paint. I intend to put the lengths in the box and have the coil outside the box with 6 small mirrow's hitting the flat black coil. I intend to make a small tank and add water with lubricant and water wetter in it.. should be interesting--well to me, at least. It may increase the heat

 

Thank you Spyman for the chart

[pioneer]

The simplest venturi affect is simply driving in an auto with the window crack about 0.5 CM. Take a cigarette and watch the smoke get pulled out. You don't have to smoke the cigarrete to do this experiment. You can use anything that smolders or makes smoke, like a fine cigar.

 

What also uses the venturi principle is the chemical injector for a pressure washer. It is a larger tube with a small side tube. The speed of the water through the larger tube, will pull a suction or vaccum that draws chemical in through the small tube. The two streams mix, to suds the house.

 

If you have a leaf blower or even the air output from a shop vac, you might be able to rig an attachment. Take the filter out for more air veocity. The attachment is a simple straight tube extension with a small side tube. You can then attach a clear hose and to see how high you can lift water. The height will allow you to calculate your vaccum.

[Oldone]

While I haven't given up, in fact, no where near it but we have been able to produce 1hg and possibly 2. We have begun to explore the possibility of electric actuation. We have used a lot of time, energy and more money than we should have. The guy at Lowes must think we have a plumbing project the size of a 10 story building.

 

Finding a good suitable unit may be a problem though. We also thought about trying to buy a tiny 12v vacuum pump.

 

 

Share your thoughts gentleman, which do you consider the best way to go?

[Spyman]

Well, I don't know much of pneumatics, airflows and such, so like Rocket Man I would use an electronic control and a electric servo to pull on the throttlewire.

 

You have not mentioned what cind of control system you are thinking of using?

(Mechanical or Electronic for speed sensing and PID-control.)

 

Can the vacuum gauge be replaced by a Cruise Control Power Solenoid?

 

Or could the vacuum gauge be boosted by applying a higher pressure on/in the casing?

 

Or can the vacuum gauge be reversed and connected to a pressure instead of a vacuum?

(Mechanically reversed push/pull on the throttlewire also.)

 

Is the flow/pressure from the exhaust enough to power a pneumatic actuator?

(Or to utilise the venturi effect better?)

 

A tiny vacuum pump? Does it have to be electric instead of powered by the engine or exhaust?

 

Maybe a trip to a junkyard and exploring solutions in old cars can give some ideas and/or parts.

 

Just some wild thoughts...

[Rocket Man]

right, so you bought a cruise control unit and you need a vacuum supply as the final touch to make it work?

 

what output does it have? do you feed the vacuum to the unit or can you give it some other actuator?

 

i have a few ideas about fudging together a digital system with an optical tacho, you could probably build the electronics into a soft drink can, if you have room for a cruise control unit, you'll have room for a servo on the throttle.

[Glider]

I don't know if this is relevant, but Harleys use a vacuum operated switch (based on a simple diaphragm) connected to the venturi of the carb. At higher revs, the vacuum activates the switch and advances the timing.

[Oldone]

Gentleman

I hope you will forgive the delay but a lot was going on. We had to give the special children's picnic and barbecue, it's a good way to raise money for children's needs.

We have come to the conclusion that it must be servo controlled. There is no way we can produce the amount of vacuum needed without going over 100 miles an hour. There is absolutely no way you can make it push and pull that I am aware of. It only has a place for one line hook up and that is for vacuum only. So with this unit will have to be servo controlled. We were going to use a cheap vacuum operated unit. We have a bicycle computer hooked up and we was going to use the reed switch to operate the speed.

 

Rocket Man

This idea you have really intrigues me. I would really appreciate it if you could acquaint me with it.

Thank you very much

Old One

[Rocket Man]

basically, if you have a pulse circuit, and you use it to reset a counter which counts how many times the wheel goes round, the counter will sit with a fairly steady maximum count determined by how fast the bike goes.

 

any reading substantially above the normal count, reduce the throttle.

any count too far below the normal count, up the ante.

 

if you paint some part of the bike black then with a dot of white, you might be able to get a count happening.

increase the pulse rate that resets the counter, the faster the bike goes.

[Oldone]

Thats exactly what the reed switch does. A magnet is placed in the brake caliper and the reed is placed on the down tube, each time the wheel makes one rotation, it breaks the circuit. Thats why a bike computer is so much more accurate than a speedometer. I should be able to tie into the existing one.

 

But I am lost as to the rest of it.

[Rocket Man]

tie into the bike computer or the reed switch?

 

actually, if you can put stuff on the speedo of the bike, you can do away with most of the gadgetry i described in the last post as well as the reed switch.

if you build the servo linkage right, and build a tiny circuit, you can have the optical gear read the speedo and modify the throttle accordingly.

[Oldone]

I can just tie to the reed switch itself. Heck, I can install another pickup if need be and use the same magnet.

I would really like to give it a go if you would be so kind as to give the info.

 

 

Well let me restate that. I have good access to the junture. The speed computer and pro oiler uses the same reed switch. I think it would be prudent to keep this on its own pickup (using the same magnet} for safety reasons. So lets make this an independent unit if you dont mind.

 

Thanks so much

OldOne

[Rocket Man]

this website has some decent info about the basics of digital electronics.

 

i know pretty much how to adapt a power supply but getting the timer/counter working properly will be the hard part. i'll see if i can brush up on my electronics enough.

i'll try to explain how my idea works a little better.

 

each time the reed trips, it adds one to a counter.

each time the timer goes off, it reads the counter, then resets the counter.

if the reading is too high, it runs the servo backwards for a fraction of a second, reducing the throttle.

if the reading is too low, it runs the servo forward for a fraction of a second increasing the throttle.

 

 

the counter should output each number on a separate pin of the chip

 

on each pin above the standard count, get some AND gates looking at it's pin of counter and the timer all telling the throttle to go down. if the timer ticks while any one of these AND gates reads a high, the throttle will reduce a tiny bit.

 

the timer should be variable so the wheel has to go around five or so times in a variable amount of time, changing the speed.

 

the main chips you'll need are the 555 and the 4017

the 555 is a popular timer and the 4017 is a popular counter.

[Oldone]

Sounds good to me, at least one of us knows what he is doing. I can get an electric servo unit for $160.00, thats nothing but the servo and throttle cable.

 

I have been known to be able to follow directions, well, at least most of the time anyway.--smile

thanks so much.

[Rocket Man]

i'm having a bit of trouble finding time to finalise the design in light of exams.

if you send an email address i can send you what i have so far.