Electric launch?

[RobertSmalls]

I have an IMA disable (clutch) toggle switch. If you close the clutch switch, put the car in 1st, and turn the key to START, the car will perform a lurching, electric launch. It's jerky, and I wouldn't try it in traffic or with a cold engine, but it gets me thinking.

What if you had MIMA, a clutch toggle switch, and an FAS relay on a toggle switch? You could turn off the fuel injectors, and use the electric motor at speeds less than 800RPM. That would allow you to drive <6mph in stop-and-go traffic without feathering the clutch. You could launch in 3rd gear (though I admit I don't know why you'd want to) and turn on the fuel injectors when you reach 25mph. You could do very short distances in EV mode, such as getting from your parking space to the edge of the parking lot without firing up the fuel injectors.

Would a smooth electric launch be useful, or merely novel? Is there any reason not to turn the engine at 100-500rpm for seconds on end? Do my motor mounts and CV axles hate me for suddenly applying the full torque of the electric motor at 0RPM?

[retepsnikrep]

Interesting but the series hybrid of the insight makes any electric only drive very inefficient due to turning over the dead weight of the engine and pumping losses etc.

In my own car I still use quite a lot of fuel to get the car up to temperature as fast as possible, reducing friction etc. As soon as lean burn is available then I start using lots of assist to keep it there.

When I did a special IMA control for the CVT rally car this was thottle operated and provided instant max assist at anything over 50% throttle. One side effect of this was that with the car stopped but with ignition on in neutral if you put foot down on throttle it would start as the IMA motor would spin it over I don't think we ever tried it in drive mode. But that may be an interesting effect.

In a manual car in 1st gear with ignition on the same effect may give the electric launch you speak off. However as soon as the engine fires you would then have full throttle as well. I might try that in my spare car just to see what happens. I suspect this would be horribly jerky though.

Pure electric launch from cold would be hideous IMO and a waste of Ah.

[02insight]

One thing I have tried is using that electric startup to help get the car moving. I can sometimes hold the clutch right before the catch point, so that when I switch the clutch switch to on while in 1st or 2nd gear, the electric motor is bringing up the engine to 1000rpm, that torque from the e-motor also helps the car launch a little smoother than having to rev to 1500-2000 and feathering the clutch to launch.

[IamIan]

I experimented with this a few years ago.

If you start in gear at 0 RPMs and try to the the IMA motor to pull out while keeping the ICE in fuel cut ... it will work ... but will lug considerably.

If on the other hand while keeping the ICE in fuel cut you get the engine up to ~1,000 or so RPMs ... then the fly wheel can smooth it out and it take pull out from a dead 0MPH stop.

Attached bellow was a run I did in 2006 of ~3.7km starting from a dead stop... It was about ~level to start ... then I traveled up a small incline of a hill for the ~3.7km.... from dead stop at point A to dead stop at point B I used No gasoline at all ... just the juice from my 6 year old at the time IMA battery... which started with a SoC at the top of the dash display.

One benefit of the Honda IMA system ... is that this technique can be used at any speed... it doesn't just have to be for pulling out and low speed parking lots.

I've found it performs best in gears 3 and under ... at higher speeds ... all you have to do to experiment with it ... is take your foot off the gas ... if you are traveling fast enough for the ICE to enter into automatic fuel cut mode ... than by using MIMA you can push the car with the IMA motor and be in EV mode...

Fuel cut can be had automatically above a certain RPM with a braking load on the engine ... or with FAS type modifications.

Even without MIMA I was able to get this mode to function ... if the IMA motor was already giving assist when the ICE looses fuel ... via fuel cut ... or FAS ... or just running out of gas... etc... If you had at least some assist already going ... than as long as I kept the throttle down enough to keep the assist going ... the out of gas EV-Mode would continue.

So... yes it works ... yes it works at higher speeds as well... and under some conditions it might be useful.

---------------now for the bad news.-----------------

The IMA motor will give you ~12HP .... you will loose some of that as you are running the ICE as an air pump ... so you really have very little power to work with.

As Peter wrote ... the extra waste in the Gen-I design means that it is not an efficient use of your Ah of battery power.... maximizing lean burn and reducing forced regen yield much better net results.

Also as Peter wrote... doing this on a regular basis to a cold engine ... will cause allot of excess wear and tear ... exactly how much and exactly what that will cost you in accelerated maintenance I don't have an exact number for you ... but it is something worth considering.

-------------------

Now if the engine is already up to temperature ... and you have a PHEV modification ... and you are almost home ... and you know you will have enough time to recharge any Ah you use ... than this can be a method of further reducing your Gasoline consumption.

Exactly how much energy it ends up using in this MIMA-EV mode will of course depend on the conditions ... up hill , down hill , level , temperature , speed , etc..etc... In my crude experiments a few years ago ... I was finding this method was yielding on average ~4 Miles per kwh of energy... which is not completely horrible ... but is still not the best use of those Ah and Wh if you will still have up coming gasoline usage needed in the trip.

[Fl_Fyr_Fytr]

Yes, this whole thing had ocoured to me as I installed the Calpod mod. Basicaly, if the switch is left on when last shutting down the car, the "clutch-in" safety feature would be disabled and the car would be allowed to try and start in gear with the clutch out.

I had thought about installing a locking relay and wiring the Calpod switch with a triple position momentary switch (up on, center dead, down off) so that when the ignition was cut, the mod would kick out. But... this would complicate the mod and decrease reliablity. A circuit would also have to be installed that would kick out the Calpod mod when the Corey switch was pushed. It all seemed like to much work just to retain that small safety feature.

[retepsnikrep]

Originally Posted by IamIan

Exactly how much energy it ends up using in this MIMA-EV mode will of course depend on the conditions ... up hill , down hill , level , temperature , speed , etc..etc... In my crude experiments a few years ago ... I was finding this method was yielding on average ~4 Miles per kwh of energy... which is not completely horrible ... but is still not the best use of those Ah and Wh if you will still have up coming gasoline usage needed in the trip.

Ian is right that's not good. My 75wh/mile is a much more effcient use of the power when helping a warmed up engine in lean burn keep returning very high mpg figures. The two complement each other very nicely. Engine in near constant leanburn + extra electric power to overcome hills/accelerate etc = Happy Face

[joecvt]

Originally Posted by retepsnikrep

When I did a special IMA control for the CVT rally car this was thottle operated and provided instant max assist at anything over 50% throttle. One side effect of this was that with the car stopped but with ignition on in neutral if you put foot down on throttle it would start as the IMA motor would spin it over I don't think we ever tried it in drive mode. But that may be an interesting effect.

FYI, awhile back, I did try this safety test in Drive mode and the engine will start and take off in Drive mode. Also did the same in Reverse mode. It takes about a second for the car to start moving since the CVT fluid has to build up some pressure to engage the forward/reverse and start clutches so not as bad as a MT started by MIMA in first gear.

JoeCVT = Just your average CVT owner