US 3651332 A
An electrical control circuit is provided for a door operator to return a door to an open position should an object be encountered by the door while moving to a closed position. The control circuit includes circuit means and a pair of normally open contacts that are closed by engagement of the closing door with an intervening object with closing of the contacts actuating the circuit means to reverse the direction of movement of the door. The contacts comprise a pair of elongated electrical conductors that are series connected with the operating coil of a relay switch which is connected in the circuit means to cause the direction of movement of the door to reverse, if initially moving to a closed position, should the contacts be caused to engage or if the interconnecting electrical conductors should either be inadvertently broken or grounded, thereby providing a fully fail-safe circuit.
Description (OCR text may contain errors)
United States Patent Cochran 1451 Mar. 21, 1972  ELECTRICAL CONTROL CIRCUIT FOR A DOOR OPERATOR INCLUDING AN AUTOMATIC CONTROL FUNCTION FOR RETURNING A DOOR WHICH IS CLOSING TO AN OPEN POSITION IF AN OBJECT IS ENCOUNTERED Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney-Mahoney, Miller & Stebens [5 7] ABSTRACT An electrical control circuit is provided for a door operator to return a door to an open position should an object be encountered by the door while moving to a closed position. The control circuit includes circuit means and a pair of normally open contacts that are closed by engagement of the closing door with an intervening object with closing of the contacts actuating thecircuit means to reverse the direction of movement of the door. The contacts comprise a pair of elongated electrical conductors that are series connected with the operating coil of a relay switch which is connected in the circuit means to cause the direction of movement of the door to reverse, if initially moving to a closed position, should the contacts be caused to engage or if the interconnecting electrical conductors should either be inadvertently broken or grounded, thereby providing a fully fail-safe circuit.
8 Claims, 2 Drawing Figures L 1 T CROR LINE 1 VOLTAGE I PATENTEDMARZI 1972 3,651,332
sun-:1 1 UF 2 INVIi/W/ PAUL E. COCHRAN BY MAHgIYVEY, MILLER & STEBENS ATTORNEYS PATENTEDMARZI I972 v 3, 651 ,332
sum 2 OF 2 4 r? CROR LINE ,2 Q VOLTAGE 4 I7 5:1 a Q n L INVEN'I'UR. PAUL E. COCHRAN BY MAHONEY, MILLER & STEBENS BY 4 Eta ATTORNEYS ELECTRICAL CONTROL CIRCUIT FOR A D OR OPERATOR INCLUDING AN AUTOMATIC CONTROL FUNCTION FOR RETURNING A DOOR WHICH IS CLOSING TO AN OPEN POSITION IF AN OBJECT Is ENCOUNTERED BACKGROUND OF THE INVENTION ing the safety function of returning the door to an open position or to prevent further closing of the door. Failure of the safety-edge or failure of the interconnecting conductors by breakage would make the safety feature inoperative irrespective of actuation of the contacts through engagement of the safety-edge with an object in the path of the closing door.
BRIEF DESCRIPTION OF THE INVENTION The control circuit of this invention is designed to eliminate this unsafe feature of the prior art apparatus in that the door will be returned to the open position at any time that the door is in transit to the closed position and either strikes an intervening objector if the safety-edge should become disabled as through breakage of the interconnecting conductors or inadvertent grounding of these conductors. This is accomplished through series connection of the two elongated conductors forming the contacts of the detector switch assembly comprising the safety-edge with each other and the operating coil of a relay switch. As a consequence of this series circuit connection, motorized operation of the door to a closed position is only possible if the safetyedge is operational and has not been damaged and, should the safety-edge become nonoperational while the door is in transit to a closed position, the interconnection is such as to automatically reverse the direction of movement of the door which will be returned to an open position. The circuit connection does not affect motorized opening of the door even if the safety-edge is not operational but will not result in inadvertent opening of the door should the safety-edge become nonoperational with respect to its intended function.
These and other objects and advantages of the control circuit will be apparent from the following detailed description of an embodiment of this invention and the accompanying drawings.
IN THE DRAWINGS:
FIG. 1 is an elevational view of a roll-type door provided with an electric motor operator and a control circuit embodying this invention:
FIG. 2 is a schematic diagram of the electrical control circuit.
DETAILED DESCRIPTION OF THE INVENTION Having reference specifically to Fig. 1, a roll-type door is shown installed in an aperture formed in a wall 1 1. This door is selectively movable between the illustrated closed position and an open position where the door is rolled into the housing 12 at the top of the aperture or door opening. Disposed at each side of the door opening are vertically extending guide rails 13 and 14 that receive the adjacent marginal edge portions of the door 10. Mechanically coupled with the ro|lmechanism of the door and indicated by the drive sprocket 15 is the door operator 16 comprising an electric motor 17 and a gear reduction unit 18 having an output shaft coupled by the sprocket chain 19 with the drive sprocket. This door structure so far described is well known and will suffice for the following description of the control circuit and its application to the door.
Electrical power from a suitable source is supplied to the motor 17 through a solenoid actuated reversing contactor 20 mounted in a junction box 21 secured to the outer frame of the motor. This reversing contactor 20 includes the two solenoids CRC and CR0 having respective pairs of line contactors CRCF and CROR connected in circuit with the power conductors to the motor 17. Energization of solenoid CRC closes its contacts CRCF to operate the motor 17 in a forward direction for closing the door 10 while alternative energization of solenoid CRO closes its contacts CROR to operate the motor in a reverse direction to open the door.
switch assembly 22 which forms the safety-edge that automatically assumes control over operation of the door operator 16 should the edge contact an object in the door opening while the door is in transit to a closed position. The illustrated switch assembly 22 is a-commercially available component comprising a pair of elongated electrical contacts 23, 24 disposed in electrically insulated relationship to each other within a protective sheath 25 that is formed from a flexible material. One contact 24 that is operated on by the sheath 25 is also preferably flexible so that engagement of the sheath with an object results in flexing of the contact 24 into electrical contact with the other Contact 23. Each contact 23 and 24 which extends substantially the width of the door 10, as does the sheath 25, is connected by respective conductors 26, 27 and 28, 29 into the control circuit as shown in FIG. 2. The conductors 26, 27 and 28, 29 are not shown in FIG. 1 other than as combined into a self-coiling cable 30 extending between a junction box 31 adjacent the sheath 25 and carried by the door 10 and a junction box 32 mounted on the wall 11 adjacent the rail 13 and situated approximately at the midpoint of the door opening.
Also mounted on the wall 11 at a convenient height adjacent the junction box 32 is a control box 33 containing four switches of the pushbutton type designated as FBI, 2 -3 and 4. The function of each will be described in conjunction with the remainder of the control circuit. Mounted on the rail 13 are three limit switches LS1, LS2, and LS3 which are shown,-
as is the control box 33 interconnected by electrical conduit 34 carrying the electrical conductors.
Each contactor solenoid CRC, CRO is connected in a respective control circuit across the control circuit power conductors 35 and 36, one conductor 36 is preferably grounded as at G with all limit switches shown in the position where the door 10 is closed. Also, all pushbutton switches are shown in their normal unactuated position. Each solenoid CRC, CRO includes in series connection therewith a respective manually actuated pushbutton switch PBl, PB2 having normally open contacts and the respective limit switch LS1, LS2 which are each of the normally closed type. An electrical holding circuit is provided for each push button switch PB1, P132 by a respective nonnally open, auxiliary contact operative by the solenoid CRC, CRO. Momentary closing of the pushbutton switch PBI PB2 resulting in energization of the respective solenoid CRC, CRO closes the associated auxiliary Contact as well as the power contactors CRCF or CROR. In addition, each solenoid circuit includes a normally closed auxiliary contact CROZ, CRC2 operated by the solenoid CRO, CRC in the other circuit with these contacts forming an electrical interlock preventing inadvertant simultaneous energization of both solenoids.
With the door 10 closed, LS1 will be open while LS2 is closed and it would only be possible to energize solenoid CRO through momentary actuation of P132 to effect opening of the door. Energization of solenoid CRO, in addition to closing line contactors CROR for energizing the motor 17 to open the door, opens contact CR 2 preventing concurrent energization of solenoid CRC and closes contact CROl which forms the holding circuit. Limit switch LS1 closes after the door has moved upwardly only a short distance, and will energize the safety portion of the circuit although the safety-portion of the circuit will be ineffective as to the opening operation. As the door reaches its upper limit of travel, limit switch LS2 will no longer remain closed but will open resulting in deenergization of solenoid CRO stopping the motor 17 and opening of contact CROl and closing of contact CRO2.
The door may now be closed through mementary actuation of switch FBI to energize solenoid CRC. Energization of solenoid CRC in addition to closing the line contactors CRCF for energizing the motor 17 to close the door, closes holding circuit contact CRCl and opens electrical interlock contact CRC2. The door will then proceed downwardly until limit switch LS1 is again opened which results in deenergization of this solenoid circuit and returns the contacts to the illustrated position.
The push button switch PB3 which is normally closed is connected in series with both solenoid control circuits and when actuated, serves to deenergize whichever circuit may have been energized and will thus stop the door in whatever position it may have been at the time. This switch not only serves as an emergency switch but permits stopping of the door at any desired intermediate position between full open or closed.
included in the safety-portion of the circuit, in addition to the detector switch assembly 22, is a relay switch comprising an operating coil CR5 and contacts CR8] and CRS2. Conductor 26 connected with contact 23 of the switch assembly also connects with the control circuit power conductor 35 through a current limiting resistor R and limit switch LS1. Conductor 29 which connects with contact 24 of the switch assembly also connects with conductor 36. Relay coil CRS is series connected with contacts 23 and 24 through conductors 27 and 28 resulting in the switch contacts 23, 24 and the relay coil CRS forming a single series circuit which maintains the relay coil in an energized state whenever the limit switch LS1 is closed. Thus, the relay coil CRS will be energized whenever the door is not fully closed and normally open contact CRSl will be closed while normally closed contact CRS2 will be open. With contact CRSl interposed in the control circuit for solenoid CRC, it will be seen that it is impossible to energize solenoid CRC unless relay CRS is energized and this will be the normal situation whenever the door is opened.
Should the contacts 23 and 24 interengage as a consequence of normal functioning of the safety-edge or switch assembly 22 in contacting an object while the door is closing, relay coil CRS would be deenergized through the effective shortcircuiting of contacts 23 and 24. Current will then flow directly through the switch assembly 22 as limited by resistor R and by pass relay coil CRS. Deenergization of relay coil CRS results in opening of contact CR3] and deenergization solenoid CRC should this solenoid be energized as is the case with normal closing of the door. This situation will also prevail should any part of the circuit connection with either the switch assembly 22 or the relay coil be inadvertently open circuited as current will similarly cease to flow through the relay coil. The open circuit condition often occurs through damage to the switch assembly or to the self-coiling cable 30 which carries the conductors 26, 27, 28 and 29. Assuming that the door 10 is fully open, it would be impossible to initiate closing of the door since relay contact CRSl would be open in the event of either open-circuiting or short-circuiting of the relay circuit. Should the short-circuit or open-circuit condition develop after initiation of a closing operation as previously described not only will further closing of the door be prevented but closing of contacts CRS2 will result in energization of solenoid CRO to return the door to a full open position. Contact CRS2 forms a bypass connection relative to the push button switch PB2 from the control circuit for solenoid CRC to that for solenoid CRO. Solenoid CRC is deenergized at this time permitting contact CRC2 to close and a circuit is completed to solenoid CRO through limit switch LS1, contact CRO2, contact CRS2, limit switch LS2 and contact CRCZ. As soon as solenoid CRO is energized, its auxiliary contact CRO! closes forming a holding circuit while opening contact CRO2. Thus, the relay switch contact CRS2 is only operational in momentarily forming the bypass circuit returning control for deenergization of solenoid CRO to limit switch LS2 which is opened when the door reaches its full open position.
A third limit switch LS3 is incorporated in the circuit to automatically eliminate the safety function when the door reaches a predetermined point in transit to a closed position. This limit switch LS3 is a normally open type connected in shunt relationship across the contacts CRO2 and CRSl and in series with contact CRCl. Having reference to FIG. 1, it will be noted that limit switch LS3 is positioned a distance above limit switch LS1 with the spacing being of the order of 6l2 inches. The function of limit switch LS3 is to eliminate the detector switch assembly 22 from affecting circuit operation while the bottom edge of the door is at or below the elevation of limit switch LS3. Safety is not substantially reduced as it is very unlikely that an object would be introduced in the door opening after the door has descended to this point and the safety circuit is prevented from functioning due to any irregularities in the door threshold that could operate on the switch assembly 22 to cause contacts 23 and 24 to engage. The
operation of limit switch LS3 is that it opens as the door moves upwardly thus enabling the safety circuit including the detector switch assembly 22 to function as previously described but again closes and disables the safety circuit as the bottom edge of the door descends below the switch LS3. Incorporation of limit switch LS3 is optional and its specific location is determined by the particular installation.
Another optional circuit element is a fourth, normally open pushbutton switch PB4 that is connected in shunt relationship to the series connected limit switch LS3 and holding circuit contacts CRCl. This switch, when actuated, bypassers the other circuit components to energize solenoid CRC and close the door 10. Switch PB4 is effective irrespective of the specific operating state of the either the normal control circuits or the safety circuit and operates as an override switch. A switch for this purpose is desirable to enable an operator to close the door by mechanically powered means in the event that the detector switch assembly 22 fail or be disconnected from the remainder of the circuit. Safety is not a factor for consideration as the operator must hold the switch closed and is thereby required to remain near the door where he can visually ascertain that no objects are obstructing closing of the door.
It will be readily apparent from the foregoing detailed description of an embodiment of this invention, that a control circuit is provided for a mechanically powered door operator incorporating a circuit connection for a detector switch that provides fail-safe operation. This circuit prevents the apparatus from being operated in the usual automatic manner if the detector switch assembly is either inoperable or is disconnected from the circuit.
Having thus described this invention, what is claimed is:
1. An electrical control circuit for a door operator drivingly coupled with a door selectively movable between a closed and an open position comprising A. control means operatively coupled with the door operator and selectively operable to control operation of the door operator from one position to the other, said control means including first and second solenoids alternatively energizable to effect opening and closing, respectively, when energized,
B. an electrical detector switch assembly mountable on the door in a position to engage an object interposed in the path of movement of an edge of the door from an open to a closed position across a space to be closed by the door, said switch assembly including a pair of elongated electrical contacts disposed in side-by-side relationship transversely to the path of movement of the door in a normally open configuration and which are closed through engagement of said assembly with an object, each of said elongated contacts having a pair of longitudinally spaced apart terminals, and
C. Electrical circuit means interconnected with said first and second solenoids and said detector switch assembly contacts for selective energization of said solenoids and including switch means responsive to closing of said switch assembly contacts to deenergize said second solenoid and to energize said first solenoid to return the door to an open position when said electric circuit means has been initially configured to close the door, said switch means having an electrically energizable actuating member connected in series with said elongated contacts and between a respective terminal of each contact with the other terminals thereof connectable to a source of electrical power thereby normally energizing said actuating member.
- 2. An electrical control circuit according to claim 1 wherein said switch means includes first normally open contacts series connected with said second solenoid and second normally closed contact series connected with said first solenoid with said last named contacts operated by said actuating member for said contacts, said actuation member normally energized when the door is not in its closed position to maintain said first contact closed and said second contact open.
3. An electrical control circuit according to claim 2 wherein said first solenoid is series connected in a respective control circuit including a manually operated switch controlling energization thereof and said second solenoid is series connected in a respective control circuit including a manually operated switch controlling operation thereof and the first normally open contacts of said switch means, the second normally closed contact of said switch means being connected to the control circuit for said first solenoid intermediate said sole noid and manually operated switch.
4. An electrical control circuit according to claim 3 wherein each of said first and second solenoid control circuits include a respective normally open contact connected in a shuntrelationship to the respective manually operated switch thereby forming a holding circuit, each such holding circuit contact being actuated by the respective solenoid to a closed position upon energization of the solenoid, and a respective normally closed limit switch responsive to position of the door series connected in each solenoid control circuit, the limit switch in the first solenoid control circuit interposed between the manually operated switch and the solenoid and responsive to the door position by being held open whenever the door is at the open position, the limit switch in the second solenoid control circuit being connected with the manually operated switch interposed between the limit switch and the solenoid with the limit switch actuated by the door to an open position when the door is in closed position.
5. An electrical control circuit according to claim 4 wherein the second normally closed contact of said switch means is connected to the control circuit for said second solenoid at a point intermediate said limit switch and said manually operated switch.
6. An electrical control circuit according to claim 5 wherein the control circuit for said first solenoid includes a normally closed contact series interposed between said solenoid and said limit switch and actuated to an open position upon energization of said second solenoid, and the control circuit for said second solenoid includes a normally closed contact series interposed between said limit switch and the connection of the second normally closed contact of said switch means and actuated to an open position upon energization of said first solenoid.
7. An electrical control circuit according to claim 5 including a normally open limit switch responsive to the door position and connected in shunt relationship to the first normally open contact of said switch means, said limit switch being held closed when the door is at or closer than a predetermined distance to the closed position.
8. An electrlcal control circuit according to clalm 6 including a normally open, manually operated switch connected in shunt-relationship to the series connected first normally open contact of said switch means and said manually operated switch in the control circuit for said second solenoid.