Flexible or portable closure – partition – or panel – Plural strip – slat – or panel type – With mounting or supporting means
Reexamination Certificate
1999-05-19
2001-03-13
Johnson, Blair M. (Department: 3634)
Flexible or portable closure, partition, or panel
Plural strip, slat, or panel type
With mounting or supporting means
C160S188000, C160S207000, C242S587100, C242S584100
Reexamination Certificate
active
06199617
ABSTRACT:
FIELD OF THE INVENTION
The invention is in the art of power lifts for doors. The power lift opens and closes a bi-fold door with reversible motor driven winches having webs anchored to the door.
BACKGROUND OF THE INVENTION
Agricultural, aviation, and commercial buildings have large side and end walls with openings to accommodate vehicles, equipment, aircraft and large machinery. Bi-fold doors hinged to side and end wall frames of the building are used to selectively open and close the openings. Bi-fold doors have upper and lower door panels hinged along adjacent sections with the upper panel hinged to the headers located above the openings. Manually operated winches have been used to open and close bi-fold doors. Winches driven with electric motors are also used to open and close bi-fold doors. The winches have cables, such as aircraft cable, and cylindrical drums which rotate to wind and unwind cables on and from the drums. The cables wind along the length of the drums which have longitudinal lengths to accommodate the cable turns. The upper ends of the cables are secured to the top of the upper door panel. The electric motors rotate the drums to wind the cables on the drums to open the bi-fold doors. When the drive of the electric motors is reversed, the cables are unwound from the drums to allow the bi-fold doors to move from the open positions to the closed positions. The bi-fold door opening and closing episodes occur at a constant speed determined by the speed of rotation of the winch drums. The cables require periodic adjustments and maintenance and are subject to wear which reduces their working life.
SUMMARY OF THE INVENTION
The invention is an apparatus for opening and closing a bi-fold door in a minimum of time without loss of headroom in the structure having side and end walls with an opening closed with a bi-fold door. The bi-fold door has upper and lower panels pivotally connected with hinges that allow the panels to be moved from a planar aligned closed position to a side-by-side open position. The upper-panel is hinged to a header extended over the doorway. A plurality of door lift devices mounted on one panel are used to selectively open and close the bi-fold door. A power unit having a reversible drive motor operably connected to the door lift devices functions to operate the power lift devices. The power lift devices have elongated flexible webs having first and second ends. The first end of the web is connected to a shaft having a member for accommodating overlapping web windings. The shaft connected to the power unit rotates in one direction to wind the web around the member to articulate the bi-fold door from the closed position to the open folded position. The speed of the opening episode of the bi-fold door increases as the door elevates to the open folded position due to the increase in diameter of the overlapped web on the member. When the shaft is rotated in the direction opposite the one direction, the web unwinds from the member to allow the door to articulate back to its closed position. The speed of the closing episode of the bi-fold door decreases as the door moves to the closed position. The second end of the web is attached to an anchor mounted on the other panel of the bi-fold door. The anchor is provided with an appliance for adjusting the working length of the web so that the bi-fold door articulates to the full open and closed positions.
The preferred embodiment of the apparatus for opening and closing a bi-fold door has a plurality of door lift devices that operate to move the door from a generally vertical closed position to a generally horizontal open position. The bi-fold door has upper and lower panels having top and bottom horizontal frame members and sheathing attached to the frame members. Hinges attached to adjacent top and bottom frame members of the upper and lower panels allow the panels to pivot to locate the panels in side-by-side relationship when the door is in the open position. The top frame of the upper panel is pivotally connected to a header extended across the top of the doorway or opening in a wall of the structure, such as a building. A plurality of door lift devices mounted on the bottom frame member of the lower panel are laterally spaced along the length of the bottom frame member. A main drive shaft connected to the door lift devices concurrently transmits torque from a power unit to the door lift devices whereby the door lift devices act together to articulate the panels from their closed positions to the folded open position. The power unit is mounted on the lower panel. The power unit includes a reversible motor and a gear box coupling the motor to the shaft. Each of the door lift devices has a winch mounted on the bottom frame member of the lower panel. The winch has a shaft connected to the main drive shaft whereby the power unit operates the winch. A cylindrical member secured to the drive shaft is connected to an elongated linear, flat and flexible web, such as a nylon or polyester web having a width of 2 or 3 inches. The web has a first end loop connected to the shaft with web guide plates attached to the shaft adjacent opposite ends of the cylindrical member and a rigid member extended through the first end loop and secured to the guide plates. A cylindrical shield surrounds the guide plates and first end loop. The shield has a slot accommodating the web which extends upwardly to a roller unit secured to the top frame member of the upper panel. The web extends over a roller rotatably mounted on the roller unit and downwardly to an anchor mounted on a frame member of the upper panel. The anchor has a sleeve attached to the second end of the web. The sleeve is rotated to wind a portion of the web on the sleeve to adjust the working length of the web. In order to maintain tension on the web, a locking nut and thread member attached to the sleeve is used to hold the sleeve and second end of the web wound on the sleeve in an adjusted position. The working lengths and tension of all of the webs of the door lift devices are adjusted so that they act together to move the bi-fold door between its open and closed positions. The drive shaft is rotated in one direction by the drive unit to wind the web in overlapping relation on the cylindrical member to articulate the bi-fold door to the open position, During the door opening episode the opening speed of the door increases as a function of the increase in the diameter of the web wound on the cylindrical member. The closing speed of the door decreases as the web is unwound from the cylindrical member.
The door lifting devices with the webs are efficient, quiet, and relatively simple structures that have heavy duty and durable characteristics. There are less maintenance and adjustments of the door lifting devices as compared to prior manual and electric door opening systems. The webs are attractive in appearance and can be replaced with a minimum of time and labor.
REFERENCES:
patent: 325986 (1885-09-01), Spangle
patent: 1962839 (1934-06-01), Repetto et al.
patent: 1994785 (1935-03-01), Premo
patent: 2152000 (1939-03-01), Stone
patent: 2274216 (1942-02-01), Sanders
patent: 3155147 (1964-11-01), Smith
patent: 4008863 (1977-02-01), Fohl
patent: 4088172 (1978-05-01), Pollock
patent: 4545418 (1985-10-01), List et al.
patent: 4609027 (1986-09-01), Keller
patent: 4949772 (1990-08-01), Ballyns et al.
patent: 5052459 (1991-10-01), Grossenbacher
patent: 5149057 (1992-09-01), Meurer
patent: 5168914 (1992-12-01), Keller
patent: 5343923 (1994-09-01), Keller
patent: 5476130 (1995-12-01), Cheng
patent: 5601131 (1997-02-01), Morris
Johnson Blair M.
Schweiss Distributing, Inc.
LandOfFree
Bi-fold door lift apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bi-fold door lift apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bi-fold door lift apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2448279