I've decided to build a hydraulic hybrid out of a Geo Metro. Been thinking about doing this for several years now.
The donor car is the mule for the Cornell XPrize team, I'm going to look at it tomorrow. My primary concern at this point is the car has power brakes so if I have an engine kill switch for pulse and glide the brakes won't work. If I have hydraulic on the rear transmission maybe its not that big of a deal though. The mule was built to test bed electric motors and batteries so it is built up with extra springs in the rear and it looks like the mounting plate for the electric motor on the transaxle is pretty beefy.
I laid in bed last night doing rough calculations in my head and got so angry that my crappy American made car has cost me over $20,000 in gas to go 160,000 miles in 10 years. It should have cost less than 1/4 of that. This country is so wasteful and I am obsessed with energy efficiency. The thought of paying $30,000 for a Prius so I can only double my mileage seems obscene to me. There has to be a better way. The XPrize really opened my yes to the advantages of very light cars and aerodynamic efficiencies. The technology is already here and the price is very affordable but big oil, big companies and big govt don't really want us driving around in cars that get 75-100mpg.
Batteries are just too heavy and too expensive. I've gone over and over it and even with Lith Ion unless you use an ultracap you need batteries that are way too big and too heavy just to get 100 miles of range. Ultra cap are too expensive and too dangerous to work with. High voltage electric systems are also dangerous and quirky to deal with.
I have traveled to about 40 countries and in a lot of countries farmers ride around on single cylinder diesel engines (tractors) with not transmissions, just straight drive trains. We are so wasteful here in the US it's insane.
Like I said my goal is to spend <$5000 for everything on the 1st gen car and to get a car that will get between 60 and 70mpg. I believe I can do it.
My first gen car will likely be just the Metro with a rear train power assist hydraulic passive system and an auto-on-off for the engine. I plan on regearing the tranny to make the gears tall so it will do <1000rpm at 55mph in the highest gear. There will also be extensive Aero modding, a plexiglass tadpole tail, wheel covers, no mirrors and a ground effect skirt made out of rubber that will be less than 2 cm from the highway surface. I expect to get constantly harassed by the cops, but damn decent milage.
The 2nd gen car will be a plug in hybrid with high density batteries and the hydraulic hybrid system that work together. The hydraulic will be used for accl/dec and the batteries will be used for high speed cruising. The gas motor will only be used when the batteries are depleted. There will be no regen braking system for batteries, all regen braking will go to hydraulic system. You lose too much energy with regen braking going to the electric system. Hydraulic is way more efficient from the standpoint of transmission losses. This car should get close to 80+mpg. It's likely that this car will also be the metro. The electic motor will mate with the rear axle. This configuration should work well on dry roads, less well on wet roads and not at all in snow and ice.
My 3rd gen car (not the geo, something different) would be a hydraulic drive car (off the shelf hydraulic drive train system not homebuilt like the first one) with a tiny diesel engine mated with a small generator and a battery pack. Plug in extended range EV similar to Volt but with a hydraulic drive train. All regen braking would go to hydraulic system not to batteries. This one would need to be ultra-lightweight and aerodynamic. I have an all Aluminum Prowler I would really like to use for this project, but not till the current engine in it dies
Currently it has over 80,000 miles so maybe another couple of years it will be ready. It will require some aero modding on the wheels and front susp members but otherwise should work well. The front bumpers and grill will have to go as well.
Right now the issues I'm thinking about are
-Accumulator size (10 Gal?)
-Spring for lightweight accumulator or get cheap one from the junkyard
-What motors will minimize leakage losses and not use too many GPM at high RPM
-How to arrange the valving mechanisms. I'm thinking of putting them where the Ebrake is and the engine kill switch on the top of the gear shifter.
- Should I put the motors in the hub or just mount one on the axle for starters
-Should I buy the hydraulic stuff new or just get old parts from a junkyard
-Minimizing losses on the hydraulic system when the motors are free spinning and the car is running on gas power.
-System by which I can refill the accumulator before I leave the house, maybe an air wrench tuning the motor manually before I leave so I can leave the house with a full hyro accumulator
- What size accumulator to use, I'm thinking 10 Gal. That should be enough to capture the energy from several stops.
Any input is always welcome.
Karl