Newsgroups: comp.robotics
Path: brunix!sgiblab!swrinde!gatech!asuvax!ennews!mcdphx!schuch
From: schuch@phx.mcd.mot.com (John Schuch)
Subject: Re: Pneumatic sphincter valve
Message-ID: <1993Sep19.191532.17632@phx.mcd.mot.com>
Sender: news@phx.mcd.mot.com
Nntp-Posting-Host: bopper2.phx.mcd.mot.com
Organization: Motorola Computer Group, Tempe, Az.
References: <1993Sep17.170825.27143@cs.ucla.edu>
Date: Sun, 19 Sep 1993 19:15:32 GMT
Lines: 33

In article <1993Sep17.170825.27143@cs.ucla.edu> alexis@humpback.cs.ucla.edu (Alexis Wieland) writes:
>
>I have an application that needs a large number of very small, cheap,
>penumatic valves.  They won't need to be particularly accurate, fast,
>leak free, or handle alot of pressure.
>
>As a possible solution, I was wondering about a "sphincter valve,"
>a short piece of tubing like material that relaxes/opens when it has
>voltage/current/heat/?? applied.
>

You might want to consider a "pinch tube" or "pinch valve." They
use a small length of flexible tubing, along with something to
pinch it shut. I have seen examples in equipment which use electric
motors, electromagnets, and pneumatics. If you have a source of
moderate pressure air, you should use the pneumatic approach. You
can get a lot more pinching force out of a small pneumatic cylinder
than you can out of anything else of the same size and weight.

You might also want to look at surplus (or maybe even new) automotive
valves. They are usually small, run on 12Vdc, and are good for
controlling low pressure air. In the car I think they are mostly
used to control vacuum. Head out to the local wrecking yard and
have a look.

BTW: as long as you are there, check out electric window motors, 
electric antennas, electric seat motors, electric rear-view
mirrors, windshield wiper motors, washer fluid pumps. All have
good robotic applications.

John


