Off-on control for an inflation aspirator

For use with a gas confining inflatable, an aspirator of a type including an aspirator tube that is extendable to open an ambient air inlet by delivery of fluid pressure into a linear fluid motor which is connected to the aspirator tube, and is retractable to close said inlet upon removal of fluid pressure from said linear fluid motor, an improved control for delivering fluid pressure to and from said linear fluid motor, comprising:

• an elongated valve plug chamber having first and second ends;
• a valve plug in said valve plug chamber having upstream and downstream ends;
• a back pressure chamber endwise outwardly of the first end of said valve plug chamber;
• a moveable wall in said back pressure chamber;
• a connector rod extending through said first end of the valve plug chamber and interconnecting the valve plug and the movable wall;
• a pressure fluid inlet for said valve plug chamber leading into the valve plug chamber upstream of the valve plug;
• a first outlet for the valve plug chamber for communicating the valve plug chamber with the linear fluid motor;
• a second outlet for the valve plug chamber for communicating the valve plug chamber with the back pressure chamber;
• means for delivering pressure fluid to and through said pressure fluid inlet into the valve plug chamber and against both the first end of said chamber and the upstream end of the valve plug to create a pressure fluid force on the valve plug for moving the valve plug axially through the valve plug chamber into a position downstream of the first outlet and upstream of the second outlet, whereby fluid pressure from the valve plug chamber is delivered through said first outlet into the linear fluid motor for powering the linear fluid motor to extend the aspirator tube;
• a passageway communicating the interior of the inflatable with the back pressure chamber, with the back pressure acting on said moveable wall to, when the back pressure reaches a predetermined level, create a back pressure force which overrides the pressure fluid force and moves the moveable wall and the connector rod to in turn move the valve plug into a vent position;
• wherein when the valve plug is in said vent position it is between the pressure fluid inlet and the two outlets and the pressure in the linear fluid motor is vented into the back pressure chamber via the first outlet, the valve plug chamber and the second outlet;
• and
• wherein such venting permits a retraction of the aspirator tube for closing the ambient air inlet.