Movable or removable closures – Safety means responsive to obstruction to closure – Sensing shoe on leading edge
Reexamination Certificate
2000-02-22
2001-09-11
Redman, Jerry (Department: 3634)
Movable or removable closures
Safety means responsive to obstruction to closure
Sensing shoe on leading edge
Reexamination Certificate
active
06286257
ABSTRACT:
TECHNICAL FIELD
The invention relates to industrial doors, in particular overhead industrial doors with closure safety mechanisms.
BACKGROUND OF THE INVENTION
Overhead doors have been used for many years to secure various enclosures including manufacturing plants, warehouses, garages, and other industrial doorways. It is well known in the art to provide a safety device on the leading edge of these doors to minimize both damage to the doors and potential injury to users when the door is closing. Such safety devices are generally coupled to a door controller. If the safety device encounters an impact, a signal is transmitted to the controller. The signal causes the door to act in a prescribed manner. For example, the controller may cause the door to stop or reverse direction.
Typically, safety edges of the type found in U.S. Pat. No. 3,462,885 to Miller are employed. In particular, the safety edge in Miller is comprised of a resiliently compressible structure. The resilient structure includes a pair of flexible contact strips which are electrically connected to a motor. Upon deflection of the resilient structure, the contact strips engage one another and transmit an electrical signal to the motor, resulting in stoppage or reversal of the door. Alternatively, pneumatically actuated safety edges may be employed. Pneumatically actuated safety edges consist of fluid-filled chambers which are coupled to pressure sensors. The pressure sensors are responsive to pulses or changes in fluid pressure within a chamber. While both of these safety edges assist in preventing damage to the door and provide some degree of safety to the users, there exist inherent limitations in both systems.
Specifically, safety edges such as those found in Miller are less sensitive to impact applied perpendicular to the door body than pneumatically actuated safety edges. Furthermore, safety edges such as those in Miller tend to allow for only minimal door over-travel.
Conversely, pneumatically actuated safety edges tend to be more sensitive to impacts in multiple directions. Pneumatically actuated safety edges, however, are more susceptible to rupture than the safety edges in Miller. For instance, a pneumatically actuated safety edge may receive a puncture or rupture in its fluid-filled chamber. Thus, changes in pressure may not be sensed by the system.
While both of the safety edges discussed above have been met with a reasonable degree of success, the present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior doors of this type.
SUMMARY OF THE INVENTION
The present invention provides a door assembly comprising a door body having a bottom edge. The door body is selectively movable up and down to open and close an opening. The door assembly further comprises a first sensor body and a second sensor body. Each sensor body is in communication with a door controller, and each sensor body has an impact portion responsive to an impact.
According to one aspect of the present invention, a door assembly is provided in which one of the sensor bodies has a greater sensitivity to impact perpendicular to the sensor body. Likewise, the other of the sensor bodies has a greater sensitivity to impact parallel to the sensor body than the first sensor body.
According to another aspect of the present invention, the location of the first sensor body with respect to the second sensor body results in one of the sensor bodies having a greater sensitivity than the other sensor body.
According to still another aspect of the present invention, the difference in the type of the first sensor body with respect to the type of the second sensor body results in one of the sensor bodies having a greater sensitivity than the other sensor body.
According to yet another aspect of the present invention, the first sensor body and a second sensor bodies are mechanically coupled, one to the other, by a hanger. The hanger extends from the bottom edge of the door body. One of the sensor bodies is disposed proximate a first end of the hanger and the bottom edge of the door body, and the other sensor body is attached proximate a distal second end of the hanger.
According to yet another aspect of the present invention, the hanger provides a contact area along the first sensor body greater than the contact area along the second sensor body, thereby allowing for an improved transfer of the force from of the second sensor body to the first sensor body.
Other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings and detailed description of the invention.
REFERENCES:
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Attached copy of photograph of a prior hanger used in connection with overhead doors which were publicly available at least as early as Nov. 1996.
Gregoriou Daniel J.
Konetzki Jeffrey
Redman Jerry
Rytec Corporation
Wallenstein & Wagner Ltd.
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