How does a roller pump work

[Pooh_Bear]

Seems to me that under pressure the fluid would just
follow the rollers as they turned inside the pump housing.
So what forces the fluid out of the pump.

Same question, but substitute a gear pump.

Pooh Bear

 

[schmism]

so the space between the gear teeth may not seal 100% letting a little fluid slip by, but it far outweighs the amount that is pushed around the "outside" edge of the gear which seals against the houseing.

roller pump does the same thing except it uses roller bearings instead of gear teeth.

 

[darkviper]

Looking at the diagram i think i have your answer. A roller pump acutally works very similar to a vane pump. However on a vane pump the rotor is not in the center of the pump. A roller is. In a roller pump the fluid also helps to seal the rollers between the casing. Each cavity as it passes the exit port because you have less area in the port(Volume) to force the liquid into as the volume is occupied between the rollers you get a pressurization of the fluid. And since you are moving the pumps rottor faster then the fluid can move by the rollers you have less leak by then you have actuall movement. That is why there is an efficiency rating on the pump. Also on most rotor type pumps the pump has to be lower then the fluid level as there is not a lot of suction power to a rotor. On a gear pump you have the fluid squezing if you will between the two gears and this creates huge amounts of pressure. Much like if you put water between your hands and close them in. The water will squezze with a pressure between your fingers. Is this the answer you need?

 

[Pooh_Bear]

I understand how vane pumps work and thought maybe that was
how roller pumps work. Still don't know what keeps the fluid from
just bypassing the exit port and going round and round in the pump.

Gear pumps now make sense to me.
I always pictured the fluid being forced between the gears.
I wondered what kept it from coming back around the outside edge.
Now I know it goes around the outside and the gear mesh seals it off.

Pooh Bear

 

[tutorbell]

If you look closely it appears that the rotor is off center from the housing. I think that the rollers move closer and farther from the center "sprocket" when they turn. At the top of the housing, the "sprocket" almost touches the wall, so this prevents fluid from bypassing the outlet.

Just my opinion, based on what these pumps look like.

 

[Brad_Blazer]

Check out this patent figure. As Tutorbell described, the rotor is eccentric to the housing. When spinning, the rollers follow the housing to create a seal. Just like a vane pump but with rollers for vanes.
ROTARY ROLLER PUMPS - Google Patents

 

[Pooh_Bear]

That explains it very nicely.

Thank you.

Pooh Bear

 

[ragkar]

One of my favorite inventions was the solution to pumping highly corrosive liquids such as sulfuric acid. Simply put, the acids flow through a teflon tube (which is immune to the acid's effects) and the rollers squeege the outside of the tube.

 

[Pooh_Bear]

Yes, it's called a peristaltic pump.
The method is also used for pumping concrete.
And for heart bypass machines pumping blood.

I hope they clean the concrete out before they pump blood.
Talk about hardening of the arteries -- OUCH.

Yeah, I know. Booooo. I just woke up.

Pooh Bear