underwater motors, use a bladder for pressure balance
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Posts: 46,084
Suggestion,
A flexible bladder which connects its own internal/flexible volume to
the internal volume of the motor can make a self pressure balancing
system with little cost or complexity. Just calculate the volume of
the flexible bladder which is needed for the depth required. The
bladder may also be pre-filled to some pressure to minimize the volume
required and prevent any water intrusion into the motor. If the
pressure is monitored a leak maybe found prior to damage.
Just a suggestion,
Ron Anderson
Digital Design Solutions, Inc.
Original Message
From: "A.C.Jacques" <acjacques@i...>
To: <basicstamps@egroups.com>
Sent: Sunday, July 23, 2000 4:15 AM
Subject: Re: [noparse][[/noparse]basicstamps] underwater motors
> There are some technologies used for sealing underwater motors;
>
> Presssure sealed:
> a) O 'ring shaft seals: low, cost, may be difficult to project and
prone
> to fail. Works well only in small angular speeds (small diameters
shafts
> or slow RPM) Low MTBF.
> b) Mechanical seals: Commercially available, Medium cost.Medium
Life.
> Low pressures.
> c) High end mechanical seals (Mag-Seal etc..) Two precision lapped
> surfaces. High cost. Very reliable. Hard to find small diameters.
> d) Two isolated shafts, magnetic coupling. High cost. Fail safe.
>
> Pressure balanced:
> a) Use oil ( low viscosity oil ) immersed motors. Use O'rings are
used
> only to avoid large oil escape or large water entrance. O'rings will
> work at same pressure at both sides. Low cost.High MTBF. Oil helps
to
> heat exchange. This method is used in commercial deep sea thrusters.
> Large RC Servo motors already are O'ring sealed. Enclosure oil
filling
> is best done with a vaccum pump.
>
> Are you looking for these motors for a pan & tilt camera system or
they
> will be used for propulsion ?
>
> ACJacques
>
> Raphael Abrams wrote:
> >
> > anybody know of a source for inexpensive submarine motors? i'm
making an
> > underwater servo controlled camera for depths of 150 feet. if the
motor
> > can come in a sort of sealed off ducted fan arrangement, that
would be
> > ideal.
> >
> > thanks!
> > raphael abrams
>
>
>
>
>
A flexible bladder which connects its own internal/flexible volume to
the internal volume of the motor can make a self pressure balancing
system with little cost or complexity. Just calculate the volume of
the flexible bladder which is needed for the depth required. The
bladder may also be pre-filled to some pressure to minimize the volume
required and prevent any water intrusion into the motor. If the
pressure is monitored a leak maybe found prior to damage.
Just a suggestion,
Ron Anderson
Digital Design Solutions, Inc.
Original Message
From: "A.C.Jacques" <acjacques@i...>
To: <basicstamps@egroups.com>
Sent: Sunday, July 23, 2000 4:15 AM
Subject: Re: [noparse][[/noparse]basicstamps] underwater motors
> There are some technologies used for sealing underwater motors;
>
> Presssure sealed:
> a) O 'ring shaft seals: low, cost, may be difficult to project and
prone
> to fail. Works well only in small angular speeds (small diameters
shafts
> or slow RPM) Low MTBF.
> b) Mechanical seals: Commercially available, Medium cost.Medium
Life.
> Low pressures.
> c) High end mechanical seals (Mag-Seal etc..) Two precision lapped
> surfaces. High cost. Very reliable. Hard to find small diameters.
> d) Two isolated shafts, magnetic coupling. High cost. Fail safe.
>
> Pressure balanced:
> a) Use oil ( low viscosity oil ) immersed motors. Use O'rings are
used
> only to avoid large oil escape or large water entrance. O'rings will
> work at same pressure at both sides. Low cost.High MTBF. Oil helps
to
> heat exchange. This method is used in commercial deep sea thrusters.
> Large RC Servo motors already are O'ring sealed. Enclosure oil
filling
> is best done with a vaccum pump.
>
> Are you looking for these motors for a pan & tilt camera system or
they
> will be used for propulsion ?
>
> ACJacques
>
> Raphael Abrams wrote:
> >
> > anybody know of a source for inexpensive submarine motors? i'm
making an
> > underwater servo controlled camera for depths of 150 feet. if the
motor
> > can come in a sort of sealed off ducted fan arrangement, that
would be
> > ideal.
> >
> > thanks!
> > raphael abrams
>
>
>
>
>