Anti-lock brakes during regen

[joecvt]

While I do understand that Honda programmed the IMA to stop regen if the anti-lock kicks in....My question is why?....I have read that it is to insure that the anti-lock has full power but that does not make sense to me.

I would think that regen and the DC-DC converter would be able to supply a consistent 12V supply to the anti-lock brake system (with the 12V battery) so I don't see where the harm is in keeping regen engaged.

Also, Insight drivers are used to the feeling of regen helping to stop the car with normal braking. When anti-lock kicks in, it feels awkward when regen stops unexpectedly (like the car is not stopping as smoothly as when regen and normal braking was occurring).

Perhaps I have overlooked some safety reason as to why they designed it this way. Anyone have any thoughts as to why?

JoeCVT - Just your average CVT owner

[IamIan]

I think it actually has to do with the legal requirements of Anti-Lock Brakes...

Anti-Lock Brakes has times in the pulses when there is no braking force... this lack of resistance to a tire from spinning can under some conditions help the tire to spin closer to road speed and thus increase the chances of getting additional traction, when the tires might otherwise have just slid.

Regenerative braking is a smooth continuous thing... it has no point of zero braking force... because of this it would negate the Anti-Lock Brakes ability to get the tire to spin up closer the road speed.

At Least the way the Regenerative braking is in the Insight... I is possible to make regenerative braking function like anti-lock brakes do... it is just more expensive....

Also remember the braking system that the car is tested with to get certified for sale in the US has to continue to function over long distances... Regenerative braking systems have two choices...
#1> don't be part of the legally required brakes... and just be and add on helper...

or
#2> be able to provide the same 100% Regenerative braking even when the Battery is full... which means you have to have some place to put the energy ... and to control the regenerative braking like anti-lock brakes do to turn on and off... and in case of failure of all electronics in the car the brakes still have to be able to stop the car in a legally predetermined distance... regenerative brakes don't function well with complete electrical failure.

[ikhoudvanu199]

ya, what he said ^

in my own words, the regen is a constant braking force, where as the ABS needs to turn on and off the brakes very rapidly in order to maintain traction, and the regen would almost negate the effects of the ABS

also, as far as the "feeling" of the regen...i know what your talking about, sometimes when my battery is close to full i wont get regen braking, and it feels wierd...but if im braking hard enough to need ABS, i am usually stopping in an emergency situation, which usually means im pressing HARD on the brakes and have the clutch in, so there would be no regen anyway...

[Dougie]

It might also have something to do with the electronic communtating of the motor. How do you make something that's juddering like crazy into a decent generator???

[joecvt]

Thanks for the replies...This is just a curiosity / desgin type question. I forgot to mention that the awkward feeling is not really during a panic stop, it is when coming to a stop at something like a red light and there are a few bumps in the road and anti-lock kicks in unexpectedly. It actually feels like the car has less control because once the regen kicks off you seem to "feel" the car surge forward more than what you are use too. It seems like my anti-lock kicks in over bumps a lot more than other cars that I drove with anti-lock brakes. I remember reading in this forum about others mentioning this too.

I guess there are some standards to adhere to in order to certify the car for anti-lock brakes and by cutting out the IMA factor (having the car behave like any other car), it was probably easier to cerify the Insight or any other Honda IMA system. I wonder if the Toyota design does the same thing....

Thanks for your replies....I guess that makes more sense than what I read was the reason (to ensure the anti-lock system has enough power).

Check out the last paragraph on this page to see what I mean:

http://www.insightcentral.net/encycl.../enbrakes.html

JoeCVT - Just your average CVT owner

[ikhoudvanu199]

Originally Posted by joecvt

Check out the last paragraph on this page to see what I mean:

http://www.insightcentral.net/encycl.../enbrakes.html

haha, if we had all looked around the site a little, it would have explained it to us...oh well, i think we all have a point