CO detector engine shutoff

[Matthew725]

I am working on a school project where I want to be able to attach a CO detector to a car so that if CO levels are dangerous inside the cabin then the engine will shut off. Our idea is to use a CO detector to send a signal to a relay that will turn off the engine when the alarm goes off. However, the CO detector sends a pulse signal to the alarm that is too short for the relay to properly shut off the car engine. In order to solve this, we are trying to use a D flip-flop to take the pulse of the alarm and send a constant signal to the relay in order to properly shut off engine. The problem is that we are not able to get the flip-flop to send a signal. We are using a CD4013BE flip flop but are reconsidering using the flip flop in the first place. Is there any way to get a buzzer signal to trigger a relay? will uplo.ad some pictures of our idea soon

 

[Bluejets]

Perhaps as an interim, a 555 could be used. As an add-on or integration into an auto system, one would imagine that any acceptable final idea would be to include it into existing ECU so maybe use a micro. I think you will find these levels are already monitored in engine emissions control.

 

[kellys_eye]

Show your schematic. The flip-flop solution should be working.

 

[Externet]

Not a good idea. Better rethink it !

Shutting the engine off can impair steering, brakes, air bags and who knows what else; risking the occupants to a much worse condition at higher speeds.

Explore loud alarm sound/lights to signal the CO condition, but keep control of the vehicle at all times.

 

[Matthew725]

Not a good idea. Better rethink it !

Shutting the engine off can impair steering, brakes, air bags and who knows what else; risking the occupants to a much worse condition at higher speeds.

Explore loud alarm sound/lights to signal the CO condition, but keep control of the vehicle at all times.

Thanks for your reply! Our reasoning for choosing this project was considering people dying from leaving the car engine on while parked, whether intentional or accidental. By demonstrating this concept it could be implemented into future car models as a built in safety feature. The dangers you stated are definitely a challenge that we will watch out for as we continue developing our idea, however right now we are just focused on trying to figure out how to shut off the engine of a car that is theoretically not moving.

 

[Matthew725]

These are the pictures of our basic idea and then circuit. Sorry for the use of only green marker!

 

[Matthew725]

Show your schematic. The flip-flop solution should be working.

Hi, thanks for your reply. We just uploaded some pictures of our idea, hopefully they are helpful.

 

[Matthew725]

Perhaps as an interim, a 555 could be used. As an add-on or integration into an auto system, one would imagine that any acceptable final idea would be to include it into existing ECU so maybe use a micro. I think you will find these levels are already monitored in engine emissions control.

Thanks for your reply! What exactly is a micro?

 

[kellys_eye]

'micro' = microprocessor - the 'brains' of all engine management units.

@Bluejets makes a valid point. Such levels are already monitored although not in the passenger compartment, but if you wanted to implement that function it would be far easier to add it to the code in an ECU than attempt to add an external module. Such a module would have to communicate with the ECU to determine if it is safe to stop the engine i.e. out of gear, stationary etc and, maybe, activate the hazard lights.

Communication with the ECU can be done over the CAN Bus or via the ODBII port (Google them for reference material) so your idea, whilst valid, needs further development to make into an integral and SAFE add-on device.

 

[Externet]

I would stay away from tinkering with the on-board-computer as it will pose a different approach for every brand/model of vehicle. And void warranties and insurances.
A relay in series with the ignition coils supply using C and NC contacts can do it.

Murphy's law clearly states that the design intended for detecting CO on an idling car will detect such condition at the speed and moment that will do the most harm.

 

[Audioguru]

You mentioned a CD4013 flip flop IC. Have you seen how low is its output current? Much too low to drive a relay but enough for a transistor between the CD4013 and the relay.

Do you have a 555 timer IC? It has lots of output current to drive a relay and can be used as a monostable to lengthen a pulse or as a set-reset flip flop.

 

[Matthew725]

This is a picture of our multisim for the idea.

 

[GeekGuy]

@Matthew725, I just stumbled on this and I'm not sure if you're still working on this ambitious project or not, but here are some references for OBD-II and the various protocols and codes.

https://circuitcrush.com/how-obd-ii-works/ (part 1)
https://circuitcrush.com/how-obd-ii-works-part-2/ (part 2)

I hope this helps!