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Velosolex

Posted: 16 Feb 2016, 01:26
by Adrian
Hi there
Somehow I came up with the idea to intsall a ECU on a Velosolex (2 stroke engine). At the beginning the idea was to install a variable ignition timing on the Velosolex. This is not new, there are ready to use units available, but they are very expensive (> € 200). Therefore I was looking for an alternative and I stumbled over the SECU-3 project. With such an ECU the possiblities are much more expandable. Here are a few ideas I would like to share with you, maybe you already have experience with this and you can give me some answers or advice, because I would like to know what is possible before I buy a SECU-3T unit. Basically I am a truck mechanic and know how an engine works, but since I usually work with diesel engines, ignition stuff with the different sensors is new to me....

My new Solex carburetor (on the way) is equiped with an adjustable fuel nozzle like this one http://www.ebay.fr/itm/Gicleur-Variable ... Swqu9U9IOw which is adjustable by just turning it in and out (screw). Would it be possible to get data from sensors like hall sensor, knock sensor and maybe MAP sensor (maybe not possible), and control a stepper motor with the SECU-3T unit, which is connected to the nozzle to adjust the mixture depending on the data the ECU gets from the sensors? Of course I would need make test runs to generate a engine characteristic map for the stepper motor positions on different engine states. If this would be possible, what additional driver would I need?

What is the working voltage of the SECU-3 untis? Would it be possible to run it under 12V?

This is how the velosolex ignition part looks like https://www.google.com/search?q=velosol ... BSAQsAQIHg

I know this sounds crazy to use an ECU for a Velosolex. But we (me and my friends) will participate a 6h race with the Velosolex next summer and I could use this a project as a electro-technic project for a school application...

Thank you in advance for your help...

Re: Velosolex

Posted: 17 Feb 2016, 03:10
by STC
Hi Adrian,
Thank you for interesting in our project.
Would it be possible to get data from sensors like hall sensor, knock sensor and maybe MAP sensor (maybe not possible),
Yes, it is possible to read and process data from mentioned sensors.
and control a stepper motor with the SECU-3T unit, which is connected to the nozzle to adjust the mixture depending on the data the ECU gets from the sensors?
Unfortunately, firmware doesn't support control of mixture on carburetor using stepper motors. But firmware supports control of mixture using PWM controlled valves and oxygen sensor. But this algorithm is designed for automotive Solex carburetor. Such system described here http://www.scribd.com/doc/6138028/Syste ... MAN#scribd
I guess your carburetor is simple one, and mentioned algorithm will not be acceptable for it.
If you will give me complete algorithm, I can try to implement it in the firmware (either stepper or PWM). I suggest you to look into the PWM side, because in this case you don't need additional drivers. Also, I think, simple PWM valves will take less space and weight.
What is the working voltage of the SECU-3 untis? Would it be possible to run it under 12V?
Yes, it is possible to run down to 6V.
This is how the velosolex ignition part looks like https://www.google.com/search?q=velosol ... BSAQsAQIHg
It is magneto. You need to throw out it and install hall sensor. Also because you can not install a big battery, you should use CDI ignition instead of simple coil.

Re: Velosolex

Posted: 20 Feb 2016, 14:30
by Adrian
Hi STC

Thank you for your reply and sorry for my late reply. I had to do some research before answering….
But firmware supports control of mixture using PWM controlled valves and oxygen sensor.
If I use a PWM controlled fuel valve, it would be better to use a non adjustable carburetor nozzle to have a more precise and stable mixture result, right? Do you think that a PWM valve would give me the same result as a adjustable nozzle? Because the adjustable nozzle adjusts the mixture by the cross sectional area and influences therfore also the nebulization of the fuel (I guess), the PWM would influnce only the amount of fuel reaching the nozzle….
I searched the web for a PWM fuel valve with the right size, I didn’t find a lot. I thought there are valves they use in the RC world, but it seems there are not many products on the market. I just found this site, but I am not sure if this valve does work with PWM: http://www.jet-tronics.de/fuelventil_en.html. Do you have any idea where to get a valve in the right size?
I guess your carburetor is simple one, and mentioned algorithm will not be acceptable for it.
Yes, I think this is true…
If you will give me complete algorithm, I can try to implement it in the firmware (either stepper or PWM)
Thank you a very much for your offer. I would prefer the PWM valve solution, because it would be easier to realize. What do you mean with „algorithm“? How can I test this and give you the right data for the algorithm?
It is magneto. You need to throw out it and install hall sensor.
I forgot to mention that I already have an electronic ignition (CDI) like this one: https://www.mofakult.ch/media/catalog/p ... 6519-1.jpg, and I realized that I can use the electronic parts (sensors and capacitor etc.) which are in the black box of the electronic ignition. I just need to open it safely and conntect it to the SECU-3T unit…..

Re: Velosolex

Posted: 22 Feb 2016, 14:01
by STC
Do you have any idea where to get a valve in the right size?
Try to google "Idle cut off valve". They work like nozzle/needle and most of them can be driven by PWM.
Do you think that a PWM valve would give me the same result as a adjustable nozzle?
Mentioned PWM algorithm works in closed-loop mode because it uses exhaust oxygen sensor. By means of PWM controlled nozzle/needle system adjusts required amount of fuel.
Thank you a very much for your offer. I would prefer the PWM valve solution, because it would be easier to realize. What do you mean with „algorithm“? How can I test this and give you the right data for the algorithm?
If existing algorithm will not satisfy your requirements, we should develop new one together.

Re: Velosolex

Posted: 23 Feb 2016, 00:49
by Adrian
Hi

I googled idle cut off valve, but I am not sure if I found the right valves and if they are PWM compatible. The idle cut off valves I found are from older car models with only one wire like this:
https://www.airheadparts.com/vintage-vw ... 58129413-d

What do you think?

Thank you for your help...