Patent Application
20120324963
1. Field of the Invention
The present invention relates to the field of automatic barrier gates and specifically to a locking system for barrier gate motors to prevent unauthorized manual operation of the gate.
2. Background Discussion
The Underwriter's Laboratory has announced new safety requirements in its UL325 standard for vehicular gate systems. This new UL standard requires such gate systems to provide manual operation so that the gate can be moved independently of the operator. (30A.1.20) Meeting that requirement can make barrier gate systems vulnerable to unauthorized opening. Typical implementations either mechanically release the gate from the operator drive train or alter the drive train's gearing to allow the gate to be driven back manually from a closed position to an open position. The latter implementation compromises security because the gate can be manually forced open any time the gate is at rest. The solution to this problem is to provide a way of locking the gate operator motor to prevent unauthorized movement of the gate while still permitting simple authorized release, which can be accomplished either electrically or mechanically.
A lock module housing containing the components of a preferred embodiment is physically mounted to the rear of the gate drive motor. A solenoid front shaft, when the solenoid is de-energized, is pushed into a sprocket attached to the drive motor, thus preventing the motor shaft from turning. To release the drive motor, the solenoid is energized. The solenoid rear shaft contacts a limit switch to indicate to the controller that the drive motor is indeed unlocked.
When the controller is about to move the gate, energizing the solenoid retracts the shaft and allows normal operation of the gate control system. At the end of the gate cycle, the solenoid is de-energized and the drive motor is once again locked.
In the case of a manual release, a key lock is turned from a first position to a second position to unlock the motor shaft. A mechanical linkage arm attached to the key lock pulls the solenoid rear shaft to its energized position, which in turn contacts the limit switch. The gate can now be back driven manually. As a safety feature, when the drive motor is mechanically released, the output of the limit switch prevents the gate controller from initiating any movement of the gate and thus preventing any injury to anyone pushing the gate.
As a convenience, an LED indicator is provided to visually indicate that the solenoid is in the energized position.
The aforementioned objects and advantages of the present invention, as well as additional objects and advantages thereof, will be more fully understood herein after as a result of a detailed description of a preferred embodiment when taken in conjunction with the following drawings in which:
Referring to the accompanying drawings, namely
The rear extending shaft 14 of drive motor 12 is mechanically engaged by a sprocket 16 which has a plurality of symmetrically positioned recesses 18. The drive motor 12 is of the type which when de-energized, automatically aligns a selected such recess 18 with a selected directional orientation, such a true vertical, in order to make the selected recess accessible to a main shaft 22 of a double-shafted solenoid 20. A second or rear shaft 24 of solenoid 20 has a linkage 26 which moves with the rear shaft depending upon whether the solenoid 20 is energized or de-energized. Solenoid shafts 22 and 24 move in tandem in the same direction. Linkage 26 is positioned to engage a limit switch 25, as well as a mechanical linkage arm 28. Arm 28 is connected mechanically to a key lock 30 through an arm actuator 32. An LED indicator 34 is preferable provided with an LED light which is visible externally through the lock module housing 15 on the right side of the motor lock module 10.
The lock module housing 15 is physically mounted to the rear of the drive motor 12 so that the rear drive motor shaft 14 extends into the module 10 and is engaged by the sprocket 16. The solenoid main shaft 22 is extended into an aligned sprocket recess 18 whenever the solenoid 20 is de-energized. Thus, shaft 22 locks the motor shaft 14 and thus locks the motor 12 when power is absent from the gate system to which the module 10 is connected. Therefore, in this mode, manual operation of the gate is prevented.
Solenoid 20 is energized to release the drive motor by withdrawing main shaft 22 from the sprocket recess 18, thereby freeing the motor shaft 14 to be manually rotated to physically open the gate barrier as required by UL-325. The solenoid's rear shaft 24 contacts limit switch 25 to indicate to the gate controller that the drive motor has been unlocked. Solenoid 20 is also energized whenever the gate controller is about to move the gate electrically so that the solenoid shaft will retract and allow normal operation of the gate control system. At the end of the full gate cycle (i.e., opening and closing), solenoid 20 is de-energized and the drive motor is once again locked.
Manual release of the gate under UL-325 is available by the action of key lock 30. With the use of an authorized key in key lock 30, arm actuator 32 is rotated from a locked position to an unlocked position. This action also rotates linkage arm 28 which pulls the solenoid shaft 24 down to contact limit switch 25 and unlock the motor shaft. The gate can then be driven manually to its open position. As a safety feature, when the drive motor 12 is mechanically released in this fashion, the output of limit switch 25 prevents the gate controller from initiating any movement of the gate, thus preventing injury to anyone mechanically pushing the gate to an open or closed condition.
It will now be understood that what has been disclosed herein is a motor locking module which may be added to an otherwise conventional gate controller system to provide motor locking and thus prevent unauthorized movement of a gate while still permitting simple electrical or mechanical release to comply with UL-325. It will be appreciated that such a locking module may take many different forms and be integrated in many different ways. Therefore, while one preferred embodiment has been disclosed in some detail to explain the structure and operation of the invention, various other embodiments will now become apparent. Accordingly, the scope hereof should be deemed to be limited only by the appended claims and their legal equivalents and not by the illustrated exemplary embodiment.
