Door controlling device

Details Door controlling device Door controlling device

2000-08-24

2002-11-26

Johnson, Blair M. (Department: 3634)

Flexible or portable closure, partition, or panel

Automatic control

With starting or driving means

C160S009000, C049S007000

Reexamination Certificate

active

06484784

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control device for closing and opening a door. More particularly, the present invention relates to mechanisms for facilitating various control operations of a door.
2. Description of the Relevant Art
Doors which close in response to a predetermined condition, such fire doors, are well known in the background art. A fire door serves as a barrier to the spread of fire, smoke or fumes through an opening or throughway in a building interior or exterior wall. Fire doors can be stored in a ceiling, wall or floor of a building, and close downwardly, sidewardly, or upwardly, respectively, to close the throughway automatically upon a sensed condition, such as excessive heat or smoke.
A rolling fire door is usually constructed of a plurality of interconnected fire-resistant slats, which are rolled up and stored on a rotating pipe over, under, or next to a throughway. Fire doors may also be of other designs. For example, a fire door could be a solid section or a combination of solid and rolling sections. Rolling overhead fire doors and other configurations can weigh from as little as a few hundred pounds to more than a thousand pounds.
Some fire doors are designed to sit open, ever vigilant for a detected fire condition. Other fire doors are operated (e.g., opened and closed) often for security and environmental reasons. These other fire doors are usually motorized, or have a manual chain hoist, in order to facilitate the opening and closing of the fire door. Most all fire doors have one or more fire links that will allow the fire door to close when excessive heat is detected. Some fire doors are also connected to smoke detector systems and alarms, so that the fire door is closed in response to excessive smoke or a fire alarm.
Rolling fire doors typically come in four types: manual push up; manual chain hoist; electric motor operated, non-automatically resetting; and electric motor operated, automatically resetting. Each type has inherent drawbacks associated with its design. The first three types are older designs, and have similar drawbacks. The fourth type is a newer design with different drawbacks, and therefore will be discussed separately.
Because a fire condition is often accompanied by a loss of electrical power, fire doors typically rely on gravity for closing, except in the case of a lightweight door, where a spring may provide a supplemental force to assist the door in closing. Side-closing, up-closing, and flat-closing fire doors also rely on springs to provide a force in the closing direction of the fire door.
Various mechanisms have been employed to slow and control the closing rate of a fire door, such as friction brakes, counter wound torsion springs, ratcheting systems and even a hydraulic resistance system (see U.S. Pat. No. 5,002,452). It is important to control the closing rate, since fire doors are mandated to drop at a rate of six to twenty-four inches per second, by fire codes.
The electric motorized types and the manual chain hoist type of fire door have a mechanism, usually a gear, held in place by a frangible fire link chain. The gear drops out of the motor gearing or chain hoist (e.g., when excessive heat is detected), so that the fire door can close independent of the motor and raising/lower mechanism. To test these types of fire doors, it is necessary to disconnect the fire link chain, so that the gear drops out.
A qualified door mechanic must reset the mechanism after a door is deployed in response to a fire condition or tested. Access to the mechanism is often limited, when the mechanism is buried in the ceiling, amid ducts, wires, and pipes. Therefore, testing and resetting of fire doors can be a costly endeavor. Fire codes require an annual testing of the fire doors. Further, many industrial plants require a monthly testing to meet the conditions of their insurance policies. The required testing is not only expensive, but also time consuming to oversee, manage, and reset the fire doors.
An additional disadvantage is that these mechanisms are prone to failure in many ways. For example, the fire door may not drop at all, resulting in major losses for insurance companies when a fire occurs. As another example, these mechanisms often do not accurately control the drop rate of the fire door, causing the fire door to crash into the floor, resulting in damage to the door, and a safety risk to anyone unlucky enough to be under the fire door when it drops. Repairing the damaged door adds to the expense associated with fire door testing, and adds to the down time associated with repairing and resetting the fire door.
The electric motor operated, automatically resetting type of fire door can be tested without disconnecting the fire link chain. This type of fire door relies on a centrifugal brake. This type of fire door has no overrun control, and, in fact, the motor acts like a flywheel, increasing the overrun. The motor can freewheel at 1800 RPM, and cause damage to the top slats of the fire door, especially on smaller doors, after only a few test drops. Additionally, there is no control on the drop speed of the fire door, other than the rate of close control, determined by the centrifugal brake, since the unit is designed to work in a no power condition.
In the electric motor operated, automatically resetting type of fire door, power must be constantly provided to the motor control mechanism in order to hold the fire door open. If power is lost to the motor control mechanism, the fire door will automatically close, even if the power outage is brief, such as during an electrical storm. If the power remains off, this type of fire door cannot be reopened for emergency personnel or emergency egress. One attempt to overcome these drawbacks has been to include an expensive battery backup system for the motor control mechanism.
Another drawback of the electric motor operated types of fire doors is the requirement of a constant source of AC power. AC power lines must be ran to each fire door. This is an expensive installation. For example, in a warehouse, where a 277 volt lighting system is the only power used, the cost of running additional high capacity power lines to the fire door controllers can exceed the cost of the actual fire doors themselves. The alternatives to these motor operated types of fire doors are the manual types of fire doors (the first and second types, above), which are difficult to test and reset, as noted above.
Both electric motor operated types of fire doors (the third and fourth types) are driven down or closed by the electric motor. Since these door controllers are designed to raise the fire doors, often when the springs are unwound, the motors have sufficient torque to cause damage to, or destroy, the door slats, if the door slats become jammed or cannot travel freely to the closed position. Often the motors will run to their bottom limit with the fire door still in the open position, while twisting, jamming, and ripping the slats in the process. This condition is also possible with other types of rolling doors, such as security grills, etc.
In summary, a general drawback of the background art's fire doors is that the typical fire door, once it closes, is difficult or impossible to open for emergency egress or to allow emergency personnel or equipment to enter. The electric types can be reopened, but only if power is still available, which is not always the case. If firemen cut a hole through the fire door to gain access, and the fire overruns their position, integrity is lost since the fire door is not and cannot be fully closed. Mechanical types of fire doors are prone to failure, and testing and resetting of the fire door is a costly operation because of the complexity of the mechanism, and the hindrance in gaining access to the operating mechanism. Electrical types of fire doors are easier to reset, but the installation of the equipment is expensive; continuous AC power is needed to keep the door open (or an expensive battery backup system); the

Affiliated with

Also associated with

Rating

Door controlling device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Door controlling device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Door controlling device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2926600