Obstruction sensor for pneumatic door operator

Claim 2

In a system for operating a door between open and closed positions and reversing a door closing cycle upon sensing an obstruction at the door, a differential pneumatic door engine having large and small cylinders and an output shaft driven by the cylinders and drivingly connected to the door, an air supply, means connecting the air supply directly to the small cylinder, an electrically operable valve for selectively interconnecting the large cylinder to the air supply to close the door or to atmosphere to open the door, flow control means between the air supply and the large cylinder, a normally open pressure switch monitoring the pressure in the large cylinder and responding to an obstruction encountered by the door, a reversing cycle relay having contacts for operating the valve to interconnect the large cylinder to atmosphere, and said pressure switch having contacts for operating said relay to close the valve contacts and cause the valve to interconnect the large cylinder to atmosphere for a door opening cycle, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

Claim 3

In a system as defined in claim 1, which further includes means for disabling the pressure switch when the door is in closed position.

Claim 4

In a system as defined in claim 2, which further includes means for maintaining the relay conditioned to hold the valve contacts closed until the door has opened to a predetermined position.

Claim 5

In a system for operating a door between open and closed positions and reversing a door closing cycle upon sensing an obstruction at the door, a differential pneumatic door engine having large and small cylinders and an output shaft drivingly connected to the door, an air supply connected directly to the small cylinder, a two-position three-way normally open exhaust-type magnet valve having a first port connected to the large cylinder, a second port connected to the air supply, and a third port connected to atmosphere, wherein the valve when de-energized interconnects said first and second ports causing the engine to close the door and when energized interconnects said first and third ports causing the engine to open the door, a normally open pressure switch connected to monitor the pressure of said large cylinder, flow control means between said air supply and said valve, a reversing cycle relay having contacts for energizing the magnet valve, and said pressure switch having contacts for energizing said relay upon detecting a given pressure in the large cylinder during the door closing cycle, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

Claim 6

In a system for operating a door between open and closed positions and reversing a door closing cycle upon sensing an obstruction at the door, a differential pneumatic door engine having large and small cylinders and an output shaft drivingly connected to the door, an air supply connected directly to the small cylinder, a two-position three-way normally open exhaust-type magnet valve having a first port connected to the large cylinder, a second port connected to the air supply, and a third port connected to atmosphere, wherein the valve when de-energized interconnects said first and second ports causing the engine to close the door and when energized interconnects said first and third ports causing the engine to open the door, a normally open pressure switch connected to monitor the pressure of said large cylinder, flow control means between said air supply and said valve, a reversing cycle relay having contacts for energizing the magnet valve, and said pressure switch having contacts for energizing said relay upon detecting a given pressure in the large cylinder during the door closing cycle, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

Claim 7

In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the outputshaft to the door, the improvement being in control means for said engine which senses a door obstruction and reverses the door closing cycle, said control means including means connecting the small cylinder directly to the air supply, a three-way magnet valve connected between the air supply and large cylinder interconnecting the large cylinder to the air supply when de-energized to cause a door clOsing cycle and to the atmosphere when energized to cause a door opening cycle, a reversing cycle relay having normally open contacts which close upon energization thereof to cause energization of the magnet valve, a pressure sensing switch monitoring the pressure in the large cylinder having contacts which close in response to a given pressure to cause energization of the reversing relay, and flow control means between the air supply and the large cylinder, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

Claim 8

In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the outputshaft to the door, the improvement being in control means for said engine which senses a door obstruction and reverses the door closing cycle, said control means including means connecting the small cylinder directly to the air supply, a three-way magnet valve connected between the air supply and large cylinder interconnecting the large cylinder to the air supply when de-energized to cause a door clOsing cycle and to the atmosphere when energized to cause a door opening cycle, a reversing cycle relay having normally open contacts which close upon energization thereof to cause energization of the magnet valve, a pressure sensing switch monitoring the pressure in the large cylinder having contacts which close in response to a given pressure to cause energization of the reversing relay, and flow control means between the air supply and the large cylinder, wherein said pressure switch and said flow control means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

Claim 9

In a system as defined in claim 5, wherein said control means further includes a limit switch in series with the contacts of the pressure sensing switch, and means for opening the limit switch when the door reaches fully closed position.

Claim 10

In a system as defined in claim 6, wherein said control means further includes a ''''stick circuit'''' having contacts which close upon the energization of the reversing relay and a normally closed limit switch and means for opening same during the door opening cycle to de-energize the reversing relay and cause a door closing cycle.

Claim 11

In a system as defined in claim 7, wherein the pressure sensing switch is set to operate and close its contacts in response to detection of about sixty percent line pressure.

Claim 12

In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the output shaft to the door, the improvement being in control means for said engine which senses a door obstruction, limits the door edge force in accordance with the resistance of the obstruction before the large cylinder develops maximum force and reverses the door closing cycle, said control means including orifice means between said air supply and said large cylinder, valve means for selectively interconnecting the large cylinder to the air supply to close the door or to atmosphere to open the door, and a pressure responsive means monitoring the pressure in the large cylinder for controlling operation of said valve means, whereby said pressure responsive means and said orifice means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.

Claim 13

In a system for driving a door between open and closed positions having a differential pneumatic door engine, an air supply for driving said engine, said engine having an output shaft and large and small cylinders driving said shaft, and means drivingly connecting the output shaft to the door, the improvement being in control means for said engine which senses a door obstruction, limits the door edge force in accordance with the resistance of the obstruction before the large cylinder develops maximum force and reverses the door closing cycle, said control means including orifice means between said air supply and said large cylinder, valve means for selectively interconnecting the large cylinder to the air supply to close the door or to atmosphere to open the door, and a pressure responsive means monitoring the pressure in the large cylinder for controlling operation of said valve means, whereby said pressure responsive means and said orifice means coact with each other to respond to a predetermined pressure in the large cylinder caused by an obstruction encountered by the door.