Pneumatic door operator having novel pneumatic actuator and lock

A power door operator of the type using a speed controlled pneumatic cylinder having an internal piston for locking and moving a door to open and close an opening in a vehicle sidewall comprising;

• a door opening in a vehicle sidewall;
• a door, moveable from open to closed positions over said opening;
• door motion forces generated by said door movement, said forces having friction, inertial, and obstruction components;
• a cylinder having fluid sealed ends;
• a magnetic fluid sealed piston slideably contained in said cylinder for reciprocal motion between said ends from a first piston door open position to a second piston door closed position therein, said motion defining a first internal piston travel distance and internal piston to cylinder end distances at each said door open and door closed position;
• first and second fluid tight volumes defined by said piston and cylinder internal said cylinder;
• fluid ports in said cylinder ends or fluid communicating said volumes and pressurized fluid sources and/or vents;
• means supplying and/or exhausting fluid to and/or from said ports
• an external piston on said cylinder;
• means mounting said external piston for motion along said cylinder, thereby defining a second external piston travel distance;
• means magnetically coupling said internal and external piston, said coupling establishing a maximum interpiston or breakaway force, said interpiston force synchronizing said external and internal piston motion and travel respectively for interpiston forces less than said breakaway value;
• means mechanically coupling said external piston and door for articulate motion therebetween, thereby moving said door to open and close said vehicular opening;
• whereby said door forces exceeding said breakaway value uncouple said door and internal piston.

A power door operator of the type using a pneumatic cylinder having an internal piston for moving a door to open and close an opening in a vehicle sidewall comprising;

• a door opening in a vehicle sidewall;
• a door, moveable from open to closed positions over said opening;
• door motion forces generated by said door movement, said forces having friction, inertial, and obstruction components;
• a cylinder having fluid sealed ends;
• a magnetic fluid sealed piston slideably contained in said cylinder for reciprocal motion between said ends from a first piston position to a second piston position therein, said motion defining a first internal piston travel distance and internal piston to cylinder end distances;
• first and second fluid tight volumes defined by said piston and cylinder in said cylinder;
• first and second opposing pressure responsive areas on said piston;
• fluid ports in said cylinder ends for fluid communicating said volumes and pressurized fluid sources and/or vents comprising;
• at least one inlet/outlet port in each end for admitting said operating fluid to said cylinder;
• at least one central vent port in each end;
• an annular internal seal seat on said vent port;
• at least one flow control port in each said cylinder end;
• means admitting pressurized fluid to said fluid ports;
• an external piston on said cylinder;
• means mounting said external piston for motion along said cylinder, thereby defining a second external piston travel distance;
• means magnetically coupling said internal and external piston, said coupling establishing a maximum interpiston or breakaway force, said interpiston force synchronizing said external and internal piston motion and travel respectively for interpiston forces less than said breakaway value;
• means mechanically coupling said external piston and door for articulate motion therebetween, thereby moving said door from open to close positions in said vehicular opening when said piston moves from said first to second positions;
• means mounting said cylinder for lateral motion from a first to a second cylinder position, said cylinder motion responsive to cylinder reaction forces generated by admitting pressurized fluid;
• means limiting said cylinder lateral motion;
• a mechanical lock operable by said cylinder motion for locking said mechanical coupling means and preventing door movement when said piston is in said second piston position in said cylinder, and said cylinder is in said first cylinder piston;
• and,
• said admission of pressurized fluid to said cylinder for producing said piston travel from said second to first position, moves said cylinder laterally from said first to second position;
• means on said lock responsive to said cylinder lateral motion for releasing said lock when said cylinder moves from said first to second positions;
• annular internal seals on said fluid ports;
• a cushion port in each cylinder end;
• a coaxial vent rod slideably contained and in said piston, said rod extending through said piston, said rod extension defining a rod sealing length, said rod having first and second ends and first and second pressure responsive areas on each said rod end, said first and second piston areas and first and second rod end areas defining a pressure responsive differential area piston, said differential area piston further defining reduced first rod end effective pressure sensitive area on said differential area piston for said internal piston to cylinder end distances less than said rod sealing length, said piston to end distance defining piston cushion travel;
• and,
• seal means on said rod ends, said seals cooperating with said internal vent port seats for terminating port flow, during said piston cushion travel, said flow termination reducing said first piston pressure sensitive area for piston cushion travel at either cylinder end.