Working for the EPA

[Xenophon]

I just got a cool summer job, I'm going to be working at the NVFEL (National Vehicle and Fuel Emission Laboratory) for the EPA starting next week. They are developing a hybrid hydraulic vehicle with UPS. Basically it is like any other hybrid car, but instead of a having a battery, generator, and electric motor, it has a pressure vessel, a pump, and a reverse pump (converts pressure into work). This is really good for large vehicles because you can generate very large torques with very good efficiencies using this method. the only two drawbacks are the size of the pressure vessels and the noise that the reverse pump makes.

I am going to be working on the circuitry and programming that controls the whole powertrain. They do everything in house, so I will be able to work with the truck, build my own circuits, and program the thing myself. I'm so stoked about this job, especially because I have been bored out of my mind sitting at home for the last two weeks.

[tinribz]

This sounds like exactly the sort of job you will be rubbish at and hate...not.

If I were you I wouldn't go back to college!

[Xenophon]

I only have one semester left and I'll have a masters degree. Then I can finally get a full time job for good.

[cryingmime]

that's freaking sweet. that sucks it's only a summer job, though...

so, correct me if i'm wrong...but is this similar to a turbocharger, only without the release of unused pressure?

this is how i picture it...the pressure builds up within the vessel (where does the pressure come from? is it via exhaust, or air intake...similar to RAM air), producing a massive amout of pressure, which releases all at once at X interval which causes work?.

i'm sure i've oversimplified it...there's a lot of engineering *magic* which happens after the pressure is released into the reverse pump...which is the real beauty of the engine... but i'm a simple person, trying to understand a complex concept (in terms that i can relate to.)

r

[mancroft]

Sounds interesting!

[Xenophon]

that's freaking sweet. that sucks it's only a summer job, though...

so, correct me if i'm wrong...but is this similar to a turbocharger, only without the release of unused pressure?

this is how i picture it...the pressure builds up within the vessel (where does the pressure come from? is it via exhaust, or air intake...similar to RAM air), producing a massive amout of pressure, which releases all at once at X interval which causes work?.

i'm sure i've oversimplified it...there's a lot of engineering *magic* which happens after the pressure is released into the reverse pump...which is the real beauty of the engine... but i'm a simple person, trying to understand a complex concept (in terms that i can relate to.)
In some ways its similar to a turbocharger, but it's not really the same.

A turbocharger increases the pressure of the air that is coming into a combustion engine. This increases the work that can be done with each stroke in the engine. However, in essense, a turbocharger is just making an IC engine more powerful. The compressor (pump) in the turbocharger is driven using the energy from the IC engine.

With the hybrid hydraulic system, the only job that the IC engine has is to increase the pressure in the system. It is not mechanically linked to the wheels at all. The pressure is what does all the driving of the wheels. It's all predicated on the reverse pump which can take pressure and turn it into the energy needed to turn the wheels.

[cryingmime]

With the hybrid hydraulic system, the only job that the IC engine has is to increase the pressure in the system. It is not mechanically linked to the wheels at all. The pressure is what does all the driving of the wheels. It's all predicated on the reverse pump which can take pressure and turn it into the energy needed to turn the wheels.

ok, now i can picture it more...but there's one piece i'm not too sure about...what is the reverse pump hooked up to? i mean...what converts the pressure into work? or is it directly connected to the wheels? forgive me if i sound stupid...i'm just trying to picture this in my head...and i'm feeling exceptionally slow-witted today.


r

[Xenophon]

The reverse pump is what converts pressure to work. If you think about what a pump does, it converts work into pressure, the reverse pump is doing the opposite.

It's hard to describe the exact mechanism, but I'll try to give you a picture of it. The reverse pump has a high pressure inlet that is attached to a little mini piston-cylinder deal, the high pressure causes the piston to be driven back in the cylinder, due to the geometry of the mechanism, this motion also causes a larger shaft that the piston-cylinder is mounted on to rotate. Once it has rotated far enough, it runs into the low pressure outlet, and the piston comes back down into the cylinder (which also causes a rotating motion). Once it gets back to the high pressure inlet, the piston is back at the base of the cylinder, causing the whole cycle to happen again. and voila, you have pressure causing a rotational movement. This is attached to the wheels through a gearbox and a drive-shaft just like any other car.

[cryingmime]

got it. thanks.

r