Hydraulics and Pneumatics

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來自 University of Minnesota 的課程

流体动力学基本原理

347 個評分

University of Minnesota

流体动力学基本原理

347 個評分

Fluid power has the highest power density of all conventional power-transmission technologies. Learn the benefits and limitations of fluid power, how to analyze fluid power components and circuits, and how to design and simulate fluid power circuits for applications.

從本節課中

Week 1: Fundamentals of Fluid Power

This week: An overview of the course, introduction to hydraulics and pneumatics, and introduction to fundamental concepts of fluid power through the cylinder.

What is fluid power?4:41

Hydraulics and Pneumatics3:16

Fluid Power compared to Electric Motors1:00

與講師見面

James D. Van De Ven, PhD
Assistant Professor
Mechanical Engineering
Will Durfee, PhD
Morse Alumni Distinguished Teaching Professor
Mechanical Engineering

Fluid power has two main categories, pneumatics and hydraulics.

And it has to do with the type of fluid.

Hydraulics is, when the fluid is a liquid, or in most

cases, oil, like the one that I have in the glass.

And pneumatics, the fluid is air, like the one that I have in this glass.

Now, hydraulics, for example, is very stiff because the fluid is stiff.

So when I push down on one piston, in my one hand, the other

piston goes up as the fluid goes through the tube to the other piston.

And, and vice versa.

And hydraulics is used in common applications such as the car jack.

Where inside the car jack, there's a hydraulic fluid that is going through the

passage ways into the cylinder that's raising the part that lifts up your car.

An example of pneumatics is found in common factory automation systems using

some of the components like the ones that I are showing here.

And Jim, if you could just hold the cylinder,

and maybe put that cup on top of it.

So inside this,

reservoir I've got some compressed air, where I pumped it up with a bicycle pump.

And let's, set that compressed air into the cylinder.

You ready?

>> Ready.

[SOUND].

>> One of the things about pneumatics, is that it's very good for on off control.

Because pneumatics has very high power density.

So when I blow up this balloon.

I can release that energy very quickly.

And as we'll see a little bit later, that's for

example why pneumatics is used in the roller coaster or the

thrill rides that we're looking at a little later, but

it's also used as a storage medium for applications such as.

Hydraulic hybrid automobiles.

So to review, for hydraulics, which is liquid

fluids the very high pressure you can get.

You can get much higher pressures with hydraulics

than you can with pneumatics, means much higher forces.

And because that oil is stiff, it means you can achieve very precise control.

But on the other hand.

This oil is toxic, you don't want to drink it because it's highly toxic.

So for example, if you have a

hydraulic machinery that's agricultural application like a

combine, you have to be very careful that this stuff doesn't get on your crops.

And then, same thing, the leaks are quite messy.

Whereas neu, with pneumatics, because that air

is springy, it makes precision control very difficult.

But, one of the nice things about pneumatics

is that when I'm releasing the air out

of the cylinder to make it go back down, I can release the air to the atmosphere.

Just releasing the air this way, which means

I don't need a return line to contain it.

And the third advantage is that, unlike the oil.

The air is free.

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