Gate operator safety system

Details Gate operator safety system Gate operator safety system

2002-06-05

2003-08-26

Wu, Daniel J. (Department: 2632)

Communications: electrical

Condition responsive indicating system

With particular coupling link

C340S545100, C340S564000, C340S870030, C049S026000

Reexamination Certificate

active

06611205

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to gate or door opening devices which control the entry and exit for personnel and vehicles from closed spaces. More particularly, it relates to electromechanically operated gates which utilize entry/exit control devices that signal the opening and closing of the gate.
BACKGROUND OF THE INVENTION
Residential, commercial, industrial, governmental and other facilities fence the perimeter or other portions of their properties for security and/or safety issues. To be practical, provisions must be made for vehicular and/or personal access to the fenced-in area. Typically some type of gate is used to restrict access to an opening in the fence. The opening in the fence and the gate are sized appropriately for the type of access required by the facility. There are many different types of gates, however most slide or swing in some fashion out of the opening in the fence.
The gate may be moved out of the fence opening either manually or by a motorized device called a gate operator or gate motor which must typically provide vehicular access. Manual operation requires a guard or attendant to stand watch and open and close the gate as required, or an occupant of the vehicle to open and close the gate. This can be costly and/or inconvenient especially in inclement weather. In addition, some people may find it difficult or impossible to move the gate due to its physical size and mass. Motorized gate operators can be used to avoid the problems associated with manual gate operation.
Gate operators are designed to provide the mechanical force required to move the gate out of the fence opening, thus eliminating the need for a person to physically move the gate. This is usually accomplished as follows. Some type of electric motor (DC or AC) is attached to a mechanical or hydraulic drive system. The final output of the drive system provides the required amount of force at a given speed to move the gate. The final output of the drive system is attached by mechanical means to the gate. Typical mechanical attachments are sprocket and chain for slide gates and articulated arm mechanisms for swing gates. A control circuit starts and stops the motor in response to user inputs such as pushbuttons, timers, limits switches, internal and external safety devices to detect entrapment, and other devices or operational conditions under which the control circuit performs a predefined series of motor start and stop operations. The gate, gate operator, and external devices must function together as a system to provide the desired access.
The control circuit of a gate operator typically has provisions for the connection of user controls or entry/exit control devices. User entry/exit control devices include pushbuttons, radio controls, card readers, keypads, loop detectors, phone systems, or similar devices. Entry/exit devices typically allow vehicular access without requiring an occupant to get out of the vehicle to activate the gate operator in the same manner. A typical gate control circuit provides the ability through the activation of a user entry/exit device to move the gate open or closed, to stop a moving gate, to stop and reverse a closing gate, and to prevent an open gate from closing.
Because gates are large and heavy gate operators can generate large forces, there is a need to guard against personal injury due to entrapment. Because of the many different types of gates and installations, there are many potential entrapment zones in a typical installed gate and gate operator system.
Unlike garage doors where the entrapment zone is well-defined, every gate and gate operator system needs to be evaluated for its own unique entrapment zones, and conditions and different installations warrant different entrapment protection devices. Entrapment may occur in both closed and open directions and each must be addressed. The gate operator control circuit must accommodate various external devices. Traditionally, external entrapment detection devices such as electric edge sensors or photoelectric sensors have been connected to the gate operator control circuit parallel with the user entry/exit devices.
In addition to the external devices, the control circuit may use some type of internal detection system such as a current sensor or rotational/speed sensor. These systems may be adjustable to compensate for various gate and installation conditions and typically operate independently from external devices. Thus, gate operators are faced with a difficult task: close the gate to secure the property and prevent unauthorized access while detecting potential entrapments and minimizing personal injury.
Until the Underwrites Laboratories Standard UL325 was revised and published in 1998, there were no specific requirements for gate operators and their entrapment detection provisions, or how the gate operator was to respond to the various types of entrapment detection devices. In the revision, UL defined installation classes and the minimum entrapment detection provisions for each class, and the response of the gate operator to the various types of entrapment detection devices.
One of the provisions of the UL325 Standard requires the gate operator to stop and sound an alarm whenever certain sequences of entrapment detection are sensed by the control circuit and activated. In this state (hereinafter referred to as the “alarm mode”) it is assumed there is an entrapment and further movement of the gate could cause personal injury. Thereafter, the gate operator may only be activated by a device that is wired to the operator and within the line of sight of the gate system. Devices such as radio controls, loop detectors or entry systems may not be used to reactivate the gate operator. Once in the “alarm mode” the gate operator may resume normal operation after reaching either an open or close limit after activation by a hardwired device as described above or a power-reset.
The wired entrapment safety station that is within the line of sight of the gate system poses a security or safety dilemma to the gate system installer and end user. A regular pushbutton may be used for the alarm mode activation, however it is active and accessible to anyone at all times and the security of the installation may be compromised. If a keyed or locked pushbutton station is used, then a key will be required for operation even in an emergency situation. This is a safety concern since it may be imperative to move the gate quickly to relieve an entrapment. The UL Standard allows the use of a reset button, however after reset, all devices connected to the gate operator may be used to activate the gate operator. Under this scenario, after reset, someone out of sight of the gate system, using a radio control for example, may be able to reactivate the gate operator in a direction that could cause additional injury.
To summarize the problem, a sequence of events such as an entrapment will cause the control logic of the gate operator to enter an alarm mode. When in alarm mode, the gate operator can only be activated by some hardwired device that is in the line of sight of the gate. To be useful as a safety device, the hardwired device (hereinafter referred to as safety station) must be accessible to the general public, however since it is accessible to the general public, it compromises the security of the installation. Hence, there is a need in the art for a safety device which meets UL standards but which does not compromise safety or security of the installation.
SUMMARY OF THE INVENTION
To solve this problem, the present safety operating system has been devised which employs an emergency control circuit within the controller which receives signals from a safety device. When the gate operator is working properly, any device connected to the safety device inputs to the emergency control circuit is ignored by the control circuit and is effectively disabled. Thus, the safety station device connected to the control circuit inputs will not activate the gate operator under normal conditions. But when the gate operator is

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