Going to start a Hydraulic hybrid project

[Gasoline Fumes]

Originally Posted by gridlok

The metro is way cheaper, but at 200,000 miles for an american car it will likely die soon.

Metros are Suzuki Swifts. The drivetrain is made in Japan and the car is assembled in Canada. 200k miles might be OK if it was well maintained. I have tons of Metro parts (will deliver too!) if you decide to get it.

How did they get the Geo Tracker rear axle in the car?

[UFO]

When looking at the BSFC, I noticed this site has a graph for the Metro engine.



It looks to me that if you did manage to reduce the power needs to run your engine on the highway at 1000 rpm, you would get terrible fuel mileage. Keep the rpms over 2000 for best mileage.

[some_other_dave]

UFO, that's a misconception. Remember, the graphs are for brake-specific fuel consumption. That means amount of fuel burned per horsepower generated. If you run the engine at 3000 RPM where it makes 55 Nm of torque, it will add energy as efficiently as possible to the car, but the car will speed up! That's not what you want when you are at cruise.

So the key for steady-state cruising is to find where the engine most efficiently generates the ~15 HP required to push the car down the road at ~60 MPH. And that isn't so easy to see from the graph. And, of course, the amount of power required to keep the car moving at a given speed is different for different speeds.

Interesting that the BSFC peak is around 3000 RPM for this engine, as opposed to around 2000 RPM as we have seen for a number of others.

-soD

[stovie]

i was looking at the hydrolic regen braking and it kind of bugs me how it doesn't use the hydrolic pump for all the braking i mean if you had a way to increase the speed of the pump so it's in the most efficent speed and there was really no need to use the brakes then that would be best but the pump is stuck at what ever gearing you have at the beginning, so i was thinking that if you got a gear set( i forget the name of the set of gears that has the orbital gear, planetary gear and the stationary gear???) you attach the orbital gear to the axle, the hydrolic pump to the stationary gear and have the planetary gears run another pump that you have a restrictor on so that when it's ingaged the restrictor slows the pump attached to the planetary gears putting power to the hydrolic pump and keeping a constant amount of pressure on the axle for braking it should also increase the hydrolic regen braking systems efficency i think????

[snowluck2345]

There are diferent types of hydraulic pumps. The one you are thinking of is a gear pump, however you could also use a swashplate pump so the compression can change more or less fluid in at atime.

[stovie]

Originally Posted by snowluck2345

There are diferent types of hydraulic pumps. The one you are thinking of is a gear pump, however you could also use a swashplate pump so the compression can change more or less fluid in at atime.

thats about what i'm thinking of, you want it to where the pump pumps more fluid on braking and use's lease fluid on the acceleration so that it conserves more of the braking power. if you end up only reducing the amount of fluid used for acceleration over braking by say 6-10% then thats 6-10% farther you can go before engaging the engine.

I can't remember where but somewhere online i saw a hydraulic pump that had a drive shaft all the way through it so you had a u-joint in front and in back, that would be pretty nice cause then you just put that between the driveline and the axle

[UFO]

Originally Posted by some_other_dave

UFO, that's a misconception. Remember, the graphs are for brake-specific fuel consumption. That means amount of fuel burned per horsepower generated. If you run the engine at 3000 RPM where it makes 55 Nm of torque, it will add energy as efficiently as possible to the car, but the car will speed up! That's not what you want when you are at cruise.

So the key for steady-state cruising is to find where the engine most efficiently generates the ~15 HP required to push the car down the road at ~60 MPH. And that isn't so easy to see from the graph. And, of course, the amount of power required to keep the car moving at a given speed is different for different speeds.

Interesting that the BSFC peak is around 3000 RPM for this engine, as opposed to around 2000 RPM as we have seen for a number of others.

-soD

That's a good point, I missed that. Maybe that really highlights how P&G can have huge returns for this engine.

[diesel_john]

Of the large farm sprayers, combines, skid loaders etc. many have hydrostatic drives and they all are less efficient than gear drives or electric drives. The reason they use hydrostatic drives is for precise control of ground speed without changing engine RPM. The first prototypes of electric drive sprayers are being unveiled at machinery shows and they are more efficient than hydrostatic. But also heavier and more expensive. The most efficient drive train at present is the diesel electric locomotives. The most efficient farm tractors presently achieve about 17 hp-hr/gal. of fuel at the drawbar, which takes into account drive train loses. We are a long way from that in cars.

[roflwaffle]

That's pretty much where most cars are give or take a hp-hr. BSFC of ~225g/kWh is ~16hp-hr/gallon, and efficient engines like VW are at ~18hp-hr/gallon. The biggest difference is the operating regime and the operators.

[diesel_john]

Drawbar hp is similiar to rear wheel hp for the car buffs. Flywheel hp can be a bit miss leading since that accounts only for the engine not the complete drive train. Tractors are rated at full load. The wheel slip % is optimized for max. efficiency on concrete. If a car had a very small direct injection engine/alternator/motor drive train so it could operate at the sweet spot all the time and no traffic constraints. Then it could exceed the tractor efficiencies, because tractors have hydraulic operated power shift transmissions not electric.