Description:
INTRODUCTION
This invention relates to power driven apparatus for opening and closing garage doors and the like and more particularly to a power operator which may be selectively stopped when the door is in a partially open position.
BACKGROUND OF THE INVENTION
A power operator for garage doors and the like typically comprises a motive power source in the form of a reversible electric motor, means for connecting the motor to the garage door to cause the door to travel between up and down limits of displacement, and an input device such as a push-button switch or radio transmitter for causing energization of the power source.
It is essential that the motor be shut off after the door has reached each of the limits of travel. To accomplish this, limit switches and adjustable switch tripping devices are typically employed. A suitable mechanism for establishing individually adjustable up and down limits of door displacement is disclosed in U.S. Pat. No. 2,951,920 to Harold L. Miller entitled "Rotary Limit Switch." The Miller patent discloses an apparatus comprising a rotatably mounted screw shaft of several inches in length and driven by the operator motor, a pair of limit switches mounted adjacent the screw shaft, and a pair of switch-actuating traveling nuts threaded on the shaft but held against rotation so as to move linearly along the shaft as the shaft rotates. One of the nuts operates in conjunction with one switch to open circuit the motor at the up limit of travel and the other nut operates in conjunction with another limit switch to open circuit the motor at the down limit of travel.
It is also necessary in a power operator of the type described above to provide means for automatically effecting a reversal of the energizing circuit through the motor at each of the limits of travel so that upon reaching the up limit, for example, the down energizing circuit is established and vice versa. To accomplish this, it is common to employ a "ratchet relay" which responds to successive operation of the input device, either push button or radio transmitter, to toggle a motor direction switch back and forth between positions which establish the up and down energizing circuits respectively. In an operator employing such a circuit reversing device, it is apparent that successive actuations of the input device cause a reversal in the dirction of door displacement irrespective of the limits of travel. Accordingly, under normal operating conditions, operation of the input device while the door is traveling upwardly causes the door to reverse immediately and move in the downward direction. Correspondingly, a second operation of the input device during motion of the door in the downward direction causes an immediate reversal and a return of the door to the up position.
It is desirable in the use of a power-driven garage door to cause the door to stop in a partially opened position so as to afford ventilation, light, and access for small animals, but without the loss of security which results from a fully opened garage door. The present invention affords such a partial opening feature in a power-driven garage door of the type having a ratchet relay or equivalent and a traveling nut limit switch arrangement having individually adjustable up and down travel limits generally of the type set forth in the Miller U.S. Pat. No. 2,951,920.
BRIEF DESCRIPTION OF THE INVENTION
In accordance with the present invention, a power operator for garage doors and the like is provided wherein the door is caused to be displaced between up and down limits of travel by successive actuations of a motive power source, such as a reversible electric motor, wherein the door may be selectively stopped in substantially any partially opened position between fully closed and fully opened positions simply by causing a second operation of the input device as the door travels toward the opened position. In general, this is accomplished by an apparatus including individual up and down limit switches and individually adjustable actuators for those limit switches for opening the up and down energizing circuits at preselected limits of travel, a toggling mechanism, such as a ratchet relay, responsive to successive operations of an input device to alternately establish the up and down energizing circuits through a motive power source and, in addition, an actuating member having a "memory" feature responsive to motion of the switch actuators to hold the down limit switch in a disabled or open circuit condition during travel of the door from the fully closed position toward the fully opened position. By virtue of the actuator device and the "memory" feature thereof, successive actuation of the input device do not cause a reversal of the door during the opening displacement, but rather simply result in alternate stoppage of the door and resumption of the upward travel. The door may, therefore, be selectively stopped in any of an infinite number of partially opened positions, the operator being such as to draw no power while the door is in the partially opened position and the operator mechanism itself being such as to substantially lock the door against further opening when in the partially opened position. The reversing mechanism, however, operates in the normal fashion during travel of the door in the downward direction, thus, to facilitate the incorporation of such safety devices as obstacle detectors, overload detectors, and the like which automatically reverse the direction of the door travel should the door encounter a car or person when moving toward the closed position.
The various features and advantages of the subject invention will be best understood from a reading of the following specification which sets forth in detail an illustrative embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified side view of a power operator for a one-piece overhead garage door;
FIG. 2 is a perspective drawing of a portion of the mechanism which represents an illustrative embodiment of the invention;
FIG. 3 is an exploded view in perspective of the components of the assembly of FIG. 2;
FIG. 4 is a side view partially in section of the apparatus of FIGS. 2 and 3;
FIG. 5 is an end view partially in section of the apparatus of FIG. 4; and,
FIG. 6 is a schematic circuit diagram illustrating the electrical interconnections between the power source, electrical voltage supply, input device, limit switches, and reversing mechanisms used in connection with the device of FIGS. 2 through 5.
DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENT
Referring to FIG. 1, there is shown a structure 10, such as a garage or utility building, having a one-piece pivotal, overhead door 12 adapted to be power driven between a fully closed position represented by the reference character 12a and a fully opened position represented by reference character 12b. The motive power source for controlling the position of the door 12 includes a reversible two-phase electric motor 35 (FIGS. 4 and 6) disposed within an operator housing 14 which is mounted adjacent the ceiling of the structure. 10. The power operator which includes housing 14 further includes a rigid rail 16 defining the longitudinal path of displacement for a traveler 18 which is pivotally connected to the door 12 by means of an arm 20. The garage door operator may, for example, include an elongated screw shaft which is suitably journaled within the rail 16 and meshing with a trapped nut to produce longitudinal displacement of the traveler 18 along the rail 16 in a direction which is determined by the direction of rotation of motor 35. The details of the drive assembly and the mechanical devices which secure the drive assembly to the door 12 are not a part of the present invention and will not be discussed in great detail.
In accordance with the invention, the limits of travel of the door 12 relative to the structure 10 may be individually and accurately preset by structure hereinafter described. Moreover, the power drive apparatus is such as to permit the door 12 to be selectively stopped in the partially opened position shown by solid lines in FIG. 1 during the upward movement of the door. The initiation of the upward travel and the stoppage of the upward travel in the selected part-open position are effected by successive operation of an input device hereinafter described so as to provide an opening at the bottom of the door for such purposes as domestic animal access, ventilation, and light.
Looking now to FIGS. 2 through 5, a portion of the structure and electrical circuit components within the housing 14 to carry out the part open feature previously described are shown. This apparatus includes a support bracket 22 having axially spaced and laterally projecting flanges 24 and 26 to support a screw shaft 28. The shaft 28 is on the order of six inches in length in the typical case. Suitable journal blocks 30 may be provided to accommodate rotation of the screw shaft 28, the drive to produce such rotation including the bidirectional motor 35, the pulley 32, and a belt (not shown). Accordingly, the screw shaft 28 rotates at a speed and in a direction which is determined by the primary drive motor 35 during movement of door 12.
Threadedly engaging the screw shaft 28 are switch actuating nuts 34 and 36 of which the position of the nut 34 on the shaft 28 establishes the limit of travel of the door 12 in the downward direction and the position of the nut 36 establishes the limit of travel in the upward direction as hereinafter described. The peripheral surfaces of the nuts 34 and 36 are notched to provide engagement with a spring biased latch plate 38 which is pivotally disposed on the support bracket 22 and resiliently secured by means of a spring 39. When the upper edge of the latch plate 38 engages the notches in the nuts 34 and 36, the nuts are restrained against rotation and, thus, are caused to move synchronously and linearly along the screw shaft 28 as it rotates. Accordingly, the relative axial spacing between the nuts 34 and 36 as well as the absolute spacing of the nuts relative to the shaft 28 is effective to determine the respective up and down limits of travel as well as the overall degree of travel which will be permitted the door 12 during operation of the power drive.
The nuts 34 and 36 perform the limit stop function in conjunction with limit switches 40 and 42, respectively, which are mounted on the support bracket 22, as best shown in FIGS. 3 and 4. The upward limit of travel is reached when the nut 36 engages the actuator of the limit switch 40 so as to open circuit that switch. Similarly, the downward limit of travel is reached when the nut 34 causes depression of the actuator of switch 42 by means of an actuator lever 46. A third limit switch 44 is also mounted on the support bracket 22 for purposes to be described.
The actuator lever 46 comprises a tab 40 at the fulcrum point and oppositely extending fingers. The lever is pivotally secured to the support bracket 22 by means of a screw 50, a nut 52, and a friction spring 54. The combination of elements 50, 52, and 54 establishes a relatively high friction condition in the pivot such that the lever arm 46 tends to remain in any angular position in which it is placed until positively driven to another orientation. By this arrangement the effect of "memory" is built into the operation of switch 42 such that when the lever arm 46 is driven in the clockwise direction by engagement with nut 34, thus, to depress the actuator of switch 42, its tends to remain in that position, continuously depressing the actuator of switch 42, until nut 36 engages the right depending arm of lever 46 and drives it back in the counterclockwise direction. The resetting of switch 42 by engagement of nut 36 with the righthand finger of lever 46 occurs when the door 12 is about three-quarters open. Accordingly, the lever arm 46, by virtue of the frictional pivot arrangement, has an ability to "remember" the condition of switch 42 established by the nuts 34 and 36 reaching one limit of travel and to maintain that condition until the nuts 34 and 36 reach nearly the opposite limit of travel.
The overall function of the apparatus and the electrical circuit components of FIGS. 2 through 5 may be best understood by reference to the circuit diagram of FIG. 6. In that circuit diagram it can be seen that input terminals 56 and 58 are adapted to be connected across a conventional 120-volt, 60-cycle power supply to energize the bidirectional two-phase motor 35. The terminals 56 aand 58 are connected across the primary winding 60 of a small conventional transformer. The secondary winding 62 of the transformer is connected in series with the coil of a bistable ratchet relay 64 and an input device in the form of a conventional spring-biased push button 68. Depressing the push button 68 causes a momentary surge of current through the relay coil 64, thus, toggling the two-position armature 66 of the ratchet relay between terminals 70 and 72. When the armature 66 engages terminal 70, current is directed from power supply terminal 58 through the switch armature 66, the down limit switch 42, and the conductor 76 to the motor 35. A second input phase is supplied to the motor 35 by way of capacitor 74 and conductor 78, thus, to produce rotation of motor 35 in a direction tending to drive the door 12 of FIG. 1 toward the down limit of travel.
The next momentary surge of current through relay 64 causes armature 66 to toggle into engagement with terminal 72 which completes an energizing circuit through the up limit switch 40 to the motor 35. One phase is supplied directly to the motor 35 by way of conductor 38 and a 90° phase shifted waveform is supplied through the capacitor 74 and the conductor 76. Accordingly, the direction of motor rotation is reversed whenever the armature 66 moves from terminal 70 to terminal 72 and vice versa. The actual energization of the motor 35 is, however, entirely dependent upon the opened and closed conditions of the limit switches 40 and 42, the bistable ratchet relay arrangement 64, 66 being effective only to establish or enable an energizing circuit in either the up or down direction.
The limit switches 40 and 42 are of the normally closed type and may be purchased from a variety of sources including the Unimax Switch Division of Maxson Electronics Corporation, Wallingford, Connecticut 06492. Switches sold under Unimax No. 3TMT 14-4 have been found satisfactory. The switches are normally closed except when the actuators thereof are depressed, i.e., moved toward the switch body by the associated switch actuating nuts 34, 36. The ratchet relay comprising coil 64, armature 66, and suitable provisions for terminals 70 and 72 is also a commercially available component and a suitable device is made by Ingrahm Industries, a division of McGraw Edison in Bristol, Connecticut 06010, their model No. C6909A.
OPERATION
Describing now a typical operation of the subject device, it is assumed that the door 12 is found in the fully opened position represented in FIG. 1 by the reference character 12b such that nut 36 is driven to the full righthand position to depress the actuator of limit switch 40. Armature 66 is in contact with terminal 72. In the fully opened condition, however, the limit switch 40 is open circuited such that no circuit may be completed through the motor 35 by way of terminal 72. The displacement of nut 36 to the righthand limit of FIG. 4 also causes counterclockwise rotation of the lever arm 46, thus, to permit the down limit switch 42 to close establishing the necessary circuit through motor 35 to produce downward rotation upon actuation of the input switch 68. Assuming now the switch 68 is momentarily depressed, the momentary surge of current through relay coil 64 causes the armature 66 to move from terminal 72 to terminal 70 completing a circuit through the now closed switch 42 to drive the motor 35 in the downward direction. Displacement of the door 12 continues until the nut 34 moves to the full lefthand position shown in FIG. 4 tipping the lever arm 46 in the clockwise direction and open circuiting switch 42.
It can be seen that displacement of nut 34 to the lefthand limit of travel also causes engagement with the actuator of switch 44, the function of which has not been hereinbefore explained. This switch operates to disarm an automatic reversing mechanism including a normally open switch 80. The mechanism includes a bumper or other suitable obstacle detector to cause switch 80 to close momentarily should door 12 encounter an obstacle during its downward travel. This acts exactly as a closure of input switch 68 to reverse the door travel. Obviously, this mechanism must be disarmed just before the door 12 reaches the fully closed position to prevent the automatic reversal and continuous cycling of the door 12 as it reaches the closed position. The subject invention is, thus, fully compatible with such automatic reversing mechanisms.
Assuming one now wishes to open the door 12, the button 68 is again depressed to produce a current surge through the coil 64 of the ratchet relay. Armature 66 moves from terminal 70 to terminal 72 to complete a circuit through the now closed switch 40 to drive the motor in suchh direction as to open the door 12. The nuts 34 and 36 move to the right as seen in FIG. 4, but the memory feature of the lever arm 14 is such that it remains in position, holding the limit switch 42 open. Accordingly, the down energizing circuit is not established while the door travels upwardly. Therefore, a second subsequent depression of push button 68 to toggle the armature 66 back to terminal 70 results in the stoppage of the motor 35 since the power supply on input terminal 58 is now directed to an open switch 42. Accordingly, the door 12 may be stopped in any partly opened position, the limit of such stoppage feature being reached only when the nut 36 reaches the righthand depending finger of lever arm 46, as shown in FIG. 4, to move it back in the counterclockwise direction to close switch 42.
In summary it can be seen that the part open feature is accomplished only when the door is displacing from the fully closed position to the fully opened position, the lever arm 46 "remembers" the closed position and the open circuited condition of switch 42 and the nut 36 has not yet reached the righthand position shown by phantom lines in FIG. 4.
It is to be understood that the invention has been described with reference to an illustrative embodiment and that various modifications and additions may be made. In addition, it is to be recognized that although the push button 68 has been illustrated as an input device, other suitable input devices including both manual and radio-operated arrangements may be employed.