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Booster Electric Motor between the auto transmission and tail shaft?

Anything to do with the electric or hybrid world

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mashableonly
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Booster Electric Motor between the auto transmission and tail shaft?

Post by mashableonly » Wed Jun 26, 2019 7:17 am

Mild Hybrid design question-
Has anyone seen or heard of adding an Electric Motor between the auto transmission and tail shaft (or at rear differential?), powered by a smallish battery pack? (simply assisting with 10-20km trips)
I have a 2001 Mitsubishi Challenger (Shogun/Montero etc other names around world; basically a Triton 4wd wagon) and would like to think its economically feasible perhaps to do this.
Electric motors are always getting smaller now and this idea may go a long way to elongating older cars lifetimes if you think about engine stress and fuel prices etc. I plan on keeping my baby for long while, hence the economic feasibility.
You'd assume the biggest hurdle will be finding a suitable electric motor (~20kw) with enough power, to fit in that tight space? (perhaps modify floor pan..)
I'd be keen to hear any ideas or leads to help make this possible.

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by Nefario » Wed Jun 26, 2019 9:22 am

A search for "hybrid booster motor sema" produces several results. E-Charger and Vonnen Performance seem to be real products.

https://www.enginelabs.com/news/sema-20 ... ws-crowds/

https://jalopnik.com/vonnen-performance ... 1829422353
Dave

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by peejay » Tue Jul 02, 2019 1:20 am

I think is how GM's truck hybrids worked.

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by Brian P » Tue Jul 02, 2019 7:42 am

The trouble with doing this in a home-grown way is the system integration. How do you interface with the driver's controls so that everything, and I mean EVERYthing, operates as it should, including safety?

Drive-by-wire throttle; how do you intercept the signal (and do it safely). How do you synchronise and blend the torque output of the engine and the electric motor? How do you make the right decisions about when to run the engine and when to shut it down?

You probably have conventional hydraulic power steering. The power steering pump doesn't run if the engine isn't spinning. Nowadays, electric servo power steering eliminates this concern.

You probably have conventional vacuum operated power brakes. This is easier to fix (electric vacuum pump) but it's still another thing for the to-do list and another line item on the budget.

If you have the budget for a fairly thorough revamping of the vehicle electronics, all this is doable. In your backyard? It's a challenge. If you can put up with driveability issues and manual monitoring and switching of devices on and off then it might be somewhat manageable, but are you really going to want to drive that?

The GM hybrids had the motor/generator integrated with the transmission. I think those had it in place of the torque converter, but I don't know if they had a second motor/generator on the output shaft. Hyundai, Honda, Mercedes, and VW hybrids all have a single motor/generator in place of the torque converter. The motor/generator is always turning with the transmission input shaft, and there is a clutch (functionally like the torque-converter lock-up clutch) allowing the engine to be coupled or decoupled.

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by BigBlockMopar » Tue Jul 02, 2019 8:01 am

I’ve been playing with the same idea, only built on an older car where things are much simpler.

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by peejay » Wed Jul 03, 2019 8:16 pm

Brian P wrote:
Tue Jul 02, 2019 7:42 am
You probably have conventional vacuum operated power brakes. This is easier to fix (electric vacuum pump) but it's still another thing for the to-do list and another line item on the budget.
Braking is the hardest part. You need to have brake by wire, and integrate the brake by wire with the electric motor/generator. Braking will regen first and apply the friction brakes second, and it needs to be done seamlessly. And, because we do this on roads that we share with other people, there has to be a safety interlock so that if the brake by wire fails, the brake pedal can apply the friction brakes the good old fashioned way.

This is old news for the OEMs.

You can do without regenerative braking, of course, but you're really missing out on the main advantage of hybrids: recovering momentum that you would otherwise throw away as heat, every time you slow down.

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by Brian P » Wed Jul 03, 2019 9:58 pm

... or you can skip trying to blend regen and friction brakes, and simply do one-pedal driving. Let off the accelerator pedal, and it regenerative-brakes (and some vehicles provide some method of having the driver adjust this). If that's not doing enough, the driver uses the normal brake pedal that actuates the friction brakes.

The one pedal (accelerator) is connected to a sensor that disappears into the existing drive-by-wire system for the engine, and you need to somehow integrate this with the electric part of the drivetrain in a way that works correctly and cannot fail-to-danger.

If the vehicle has conventional hydraulic power steering driven by the engine which you are proposing to leave stopped while driving, it isn't going to work. That's a safety issue.

When the vehicle is operating on electric power, neither the air-conditioning (driven by the engine) nor the heating (uses heat produced by the engine) will work. That's a nuisance. A do-it-yourselfer would probably put up with manually switching to engine-running mode if HVAC is necessary (e.g. to defog the windows in humid weather).

The system integration at the OEM level is merely a chore for the programming and calibration department. For a backyard do-it-yourselfer, it's a major obstacle. Remember, it has to not only work but it has to be safe.

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by peejay » Sun Jul 07, 2019 2:25 pm

Brian P wrote:
Wed Jul 03, 2019 9:58 pm
... or you can skip trying to blend regen and friction brakes, and simply do one-pedal driving. Let off the accelerator pedal, and it regenerative-brakes (and some vehicles provide some method of having the driver adjust this). If that's not doing enough, the driver uses the normal brake pedal that actuates the friction brakes.
That would be incredibly difficult. Remember, people today are too lazy to do anything but turn their cruise control on and drive nose to tail in the center lane. Having to constantly hold the accelerator in a certain position would result in a complete mental breakdown.

The amount of regenrative braking modern hybrids can do is astonishing. You almost don't need friction brakes at all, except for emergencies.

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Re: Booster Electric Motor between the auto transmission and tail shaft?

Post by gruntguru » Sun Jul 07, 2019 8:10 pm

Haven't experienced it myself but I've spoken to a few that have. They all say your foot learns to do it very quickly. Cruise control is still there when you need it, stop start driving is easier with one-pedal driving, maintaining speeds in all other situations is no different than two-pedal driving.

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