Geo Metro plug-in parallel hybrid EV - in progress

[eco_generator]

Simple execution. I love it.

If there was some way to get your electric motor to move with the hub on an arc, then the gears and chain would always be in the same plane, and equidistant. Like a curved slot that the motor would bolt onto. That'd be really cool.

[Coyote X]

I have had a few random ideas on taking the movement out of the lower sprocket. Nothing has really been ideal. Limiting the suspension will work but make it ride even rougher than it did before. I don't really mind a rough ride but there needs to be a little bit of give somewhere. The 51psi tires don't flex much so it would be a really bouncy ride. Attaching the electric motor to the suspension so it moves with the axle would probably work but it would be a really complicated mounting setup and I am not sure how it could be made easily. I am open to any ideas though

So far my best working idea is to seriously shorten the axle to be about an inch long and put a chassis mounted bearing set on the new end and connect it to a second short CV axle that runs out to the wheel. That way the center bearing set could be attached to the chassis and be fixed position with the sprocket on it. The inner cv axle could let the engine move around all it wants and the outer axle would take up the suspension movement. I could also change over to a belt drive with that setup and keep the vibrations down if it is bad enough to worry about.

The only issues with a setup like that is I need to move the engine over to the passenger side like 3 inches to make some room. I don't think it would be difficult just time consuming and getting into a lot more custom parts than I really wanted.

Right now even if I mounted the sprocket to the inner CV hub the motor mounts let it flex enough when the electric drive is engaged that it moves the sprocket about 1/2 of an inch. That movement with the suspension movement is what is making the chain skip while driving. I would have to attach the electric motor to the gas motor and when driving on electric only it would be putting some really bad stress on the differential bearings and probably kill them quickly. With chassis mounted bearings That would eliminate all the forces in strange directions being put on parts not designed for them.

[eco_generator]

Wow, as I actually flesh out some of my ideas (some with the help of Autocad) - you actually have a pretty good problem on your hands!

Even if you keep the sprocket's relative angles the same, they shift into different planes like this: _ - <-- not to scale...

But like you have said, with minimizing the motion of the suspension; then just a little bit of self-correcting measure would make a large % difference. I have an idea, but I'm researching to find out if it exists! It would be something simple, but I don't if it would work in the real world.

Something similar to a spherical bearing to allow this motion:

But the bearing and it's housing would have intermeshing teeth or ridges to allow that changing angle but transfer torque from the housing to the rod... ehh, I don't think it exists. Bummer.

[Coyote X]

The other problem that makes it even harder is that whatever solution needs good bearings and seals to keep the oil or grease in. I am trying to make the car long term reliable without a huge amount of maintenance to keep it going.

So far my only working solution is to split the axle in half like I posted and move the motor over a few inches to give me enough room for 2 axles with a chassis mounted set of bearings.

Maybe this picture will make what I was talking about make sense



With just a few more inches of room that would work and solve all the stress and movement problems and just add the problem of future cv joint replacement headaches. The only problem I see with that setup is to make the 2 new joints that connect in the center come apart easily somehow so I can replace the sprocket when it wears out.

[eco_generator]

I had the same idea, using 2 u-joints on each side. But that would change the overall length of the axles pretty good to get any angle.

And with your idea, would you really need 2 cv joints on each side? Since you are attaching the sprocket solidly anyways, couldn't the inside just be a straight shaft from the tranny into the sprocket (or just keep the one original cv joint by the tranny)? Make those chassis mounted bearings into bearings inside a rubber bushing and just have the new cv joint (actually would need to be a double offset joint) on the outer side handling a larger angle. Then you would just need one custom axle with a shorter middle shaft. Those aren't too hard to order (or make for the backyard machinist). I assume you don't plan on driving 120 mph in this thing.

And on the plus side, no engine moving required without the extra cv joint, if I am understanding what you are saying correctly.

[Coyote X]

A straight shaft into the transmission is possible. But the motor has rubber mounts so the motor can move up to an inch in any direction. The bearings would have to be attached to the motor and would move with it instead of the chassis where they would bind when the motor moved. It would be possible to just mount the straight shaft bearings to the transmission and move the electric motor to it also. That would isolate the entire thing from vibration and still eliminate the stresses on the transmission bearings

More stuff to think about

[Geebee]

Any way to setup the drive to the rear wheel? a rear axle/ diff setup from a rear drive car?
Or trike it and use a rear motor bike half to completely seperate the drives.
at least you could still have suspension.

[eco_generator]

Mounting everything relative to the engine would definitely help with all the tensions and stresses put on the different components. Plus, it sounds like it wouldn't hurt to upgrade your engine/tranny mounts with something a little stiffer. Less movement in the rubber bushings means more power to the ground --> more efficiency, right?

And you might want to think of some simple spring powered tensioner for the chain. That might help immensely with the skipping problem. And you'd have no problem using something like this to let the tensioner sprocket align with the chain:

Since it does not have to transfer power and all.

[MetroMPG]

Any news Rick?

I'm sure you already know that the 4 cylinder version of the car had a straight shaft out the right side of the transaxle to a hanger bearing. The inner CV joint was on the outside of that bearing.

You can see it in this pic of the ForkenSwift's motor compartment:



The problem is that there's not likely enough room for the sprocket that size (clearance to the back of the engine). So if you were to do it, you'd have to do reduction somehow. Oh, and relocate your motor somehow.

Just thinking out loud.

[eco_generator]

I noticed the same thing when changing the oil on my Camry. There is a straight shaft that goes to a large bearing and the axle attaches to that.

I am sure he could rework the mounting to make a sprocket fit.