inline driveshaft motor?

[Christ]

Originally Posted by almightybmw

So Christ, when you said it would present problems with being in 4HI, the OP is looking for a low speed electric only option, which with the xfer case in 4HI and the trans in neutral, this would drive the rear axle without problems. When he wants to go faster, slip the clutch, start the engine, disengage 4HI. I have an electric xfer case, and the motor does not need to be on for it to engage (although the vacuum actuated front diff does need the engine on).

Seems pretty cut and dry to me. Engage 4HI, shift to neutral, start the motor. Reach peak speed of motor, start engine, disengage 4HI, drive like normal. There really would be no limit on speed, only on the internal gearing of the electric motor, and the final drive ratio. No motor gearing? Example: My truck's final is 3.73, so that would be my electric motor ratio.

I'm giving this information with the assumption that he doesn't have shift-on-the-fly capability in 4wd modes.


EDITED: The rest of the information contained in this post didn't apply to the situation.

[windrider919]

Hi all. Well, I'm new here but I will throw my two cents in.

Why do so many state that the motor would be overspeeding when the engine is driving it? Motors usually are variable speed or constant speed but in my experience as a millwright run at 1800, 3600 or 4800RPM. I have even seen specialty motors run at 6k RPM. Now most piston engines have an RPM range of 600(idle) to 4500 [+- redline, depending on part balance, etc] and then the torque is delivered to the transmission which.....wait for it......REDUCES the output RPM.

In lower transmission gears, the engine creates more RPM and more horsepower, which is important for accelerating when taking off. In straight drive, the output of the automatic transmission is turning at the exact same speed as the engine. In a manual transmission the same rule applies in the gear before overdrive. In overdrive, the output of the transmission is actually turning at a faster speed than the engine. Overdrive is great for fuel mileage. But even then we are only talking maybe 10% faster. Changing the trucks gear axle ratio, affects the engine RPM at a given speed and the wheel speed. As an example if the objective were to save fuel, the axle ratio would be changed to a higher gear ratio. If the trucks gear ratio is 4.10 and was changed to a higher ratio like 3.55, the engine would turn approximately 15% slower, everything else being equal.

Since most engine / transmissions gearing are set to cruse at 2400 to 3600RPM at 55/60 down the road the drive shaft must be turning at a RPM either slower or at about engine RPM.

Roughly calculating backwards (reverse engineering as a check):
24” tall tire x 3.1415 = 75.4” / 12 = 6.283' circumference

1Mile = 5280feet

60mph = 5280 ft/min / 6.283' = 840.36 RPM of the tire

With a 3.5:1 rear end that should be: 3.55 X 840.36 = 2983.3 drive shaft RPM

So an electric motor would NOT be overspeeding in direct drive.

Note: In this application, Brake regeneration would work quite well to recharge the battery bank For example, in Ford F350s there already is a drive line brake which is also the emergency brake. It might require some control synchronization but the hardware is already out there.

In this application the electric motor would be able to INCREASE the torque to the rear end if used in combination with the IC engine if linked to the engine throttle. With todays high torque motors the acceleration could be awesome with low 0-60 times.

Another point that I saw was that the engine powers the power steering and the brake booster. If the engine is cut off the control forces will increase significantly. Unless they have been disconnected from the engine and powered separately. Again, that conversion is available as a kit for increasing available engine HP just like electric fans replacing direct drive fans do.

If a manual transmission then switch over would be easy, put it in neutral and kill the engine, drive on electric. But if the truck is an automatic then there is the problem of the trans fluid pump not operating when the engine is not running. It would be the same as if the truck were being towed. And everyone should be aware that the trans bearings will burn up from lack of lubrication in a short (relatively) period. hats why tow trucks lift the drive wheels on an automatic transmission vehicle. Again, there are kits to correct this situation. Cars with auto trans being towed behind RVs MUST have an auxiliary electric pump to circulate the trans fluid while being towed. That too could be added to the truck. Another point was made of adding the motor torque into the transmission via the transfer case. That could work but I question how some of the clutches, etc would work if driven backwards. And of course there is the battery bank to be considered, expensive no matter what type used because you need so many of them for any mileage at all.

The bottom line is that it is probably not a economic conversion. It could be done but the hybrid vehicle would be the worst of all worlds. At least in my opinion. Thats why we don't see them on the streets today, not cost effective.

Hey, I'm new. Like I said, my .02 worth.

[Christ]

Now go back to the original issue...

If the motor were attached in a gear/chain fashion, it could be made to overspeed. That was the concern. Thanks for the mile long write up, though.

By the way - when did a mile's length increase six-fold?

Mile = 5280 feet.

60 MPH = 5280ft/min.

And just to be picky - Most vehicles with 4wd with manually selectable transfer cases, and some with automatic xfer cases (electric/vacuum select) can be flat towed with no auxiliary equipment. T case goes in neutral, car go bye-bye down the road behind an RV.

Saturn automatic transmissions are built specifically to be flat towed. They needn't have the drive wheels lifted off the ground, and needn't have any extraneous BS installed.

Welcome to EM!

[windrider919]

Whups, I made a calculator error. Now I have to go back and re figure.
(post #52 corrected)

I knew about the Saturn but still, in general, most automatic transmission cars cannot be towed.

Why would any one really want a chain drive? they are noisy, need frequent adjustment and loose power. The are used on bikes but the above applies.

[Christ]

The question about overspeeding came when I suggested a gear driven application which used a lower power lower weight motor coupled to the driveshaft via gear/chain in reduction.

If the max RPM of the motor was 6000 RPM, and it could only propel the vehicle up to 20 MPH at max RPM, anything faster than that (vehicle speed) would overspeed the e-motor due to the resultant gear multiplication.

[Ryland]

Originally Posted by windrider919

Why would any one really want a chain drive? they are noisy, need frequent adjustment and loose power. The are used on bikes but the above applies.

I've driven three chain driven cars, a Saab 900, a Saab 93 and a Honda N600, all of them worked just fine with a chain between the engine and the transmission.

[Christ]

Originally Posted by windrider919

Whups, I made a calculator error. Now I have to go back and re figure.
(post #52 corrected)

I knew about the Saturn but still, in general, most automatic transmission cars cannot be towed.

Why would any one really want a chain drive? they are noisy, need frequent adjustment and loose power. The are used on bikes but the above applies.

They're not really that bad... honestly. Most vehicles with chains for any purpose also come with a tensioner, which voids the "needs adjustment" argument.

Several older t-cases have chain drives in them, so they're plenty strong enough, and you can't really hear them if they're properly lubricated, so that voids the "noisy" argument.

As far as losing (loose-ing) power, that's simply not true either. While some parasitic power loss can be noted by the chain's movement, and the weight and friction of parts, you're talking a very minute amount, compared to things like tire friction, which also represent a very small amount of drive train losses.

[windrider919]

Chain drives serve a useful purpose or we would not have them. I have even flown in a HiVel chain driven airplane (between the chev 350 n the prop shaft, drive n speed reducer). But looking at the real world maintenance records of fleets of vehicles and industrial machinery they do not have the longevity or reliability of gears. Hey, I would sure rather have a timing chain than a timing belt in my engine! There are exceptions, I know a guy locally with a Saab 900 with almost 300k miles that has never had to be repaired. But a lot of them have had to be. I was not putting down chain drives, just saying that the inline drive motor would be better, in this application, in my opinion. Because I could not see him acquiring a HD cased chain transmission unit due to the cost. Salvage, maybe if lucky. Any DIY chain drive would be a major project in itself and I was just trying to apply the KISS principle. Since an encased unit seemed unlikly in this project the next possibility was an open/exposed chain drive and hence my comments on noise, wear, etc.

As per overspeeding the first thing I would install in such an application is an overspeed clutch between the sproket n the motor

[orange4boy]

Good discussion here.

I have wanted to do this in my van for a while but it's too big a project for me. Fun to read all the ideas though.

The only "simple option" for me is to install an electric motor inline with my accessory drive shaft which comes off the front of my motor and therefore could only be an assist motor with possible partial regen braking.

Motor control would be the biggest obstacle in my mind. Would have to have a brake switched disable or regen and some sort of proportional power control. Possible with some electronics smoke and mirrors. Possibly a pot in parallel with the throttle?

Simple method could be series parallel contactors for voltage power control and use it only for set conditions.

[Christ]

Hell, that's too complex... I just want a 5HP motor that will get me going around town w/o using gasoline... Nice thing about my FWD van is that other models came equipped with AWD... if I were so inclined, I could easily swap out the current rear for an AWD unit, and hook it up to an E-motor via a CV shaft.