Counterbalancing mechanism for rolling doors

    公开(公告)号:US3981343A

    公开(公告)日:1976-09-21

    申请号:US508404

    申请日:1974-09-23

    Applicant: George DeVito

    Inventor: George DeVito

    Abstract: A counterbalancing mechanism for an articulated rolling door mounted for movement horizontally away from the doorway when the door is opened, with the weight of the vertical portion of the door producing variable forces urging the door towards its closed position as the door is moved between its open and closed positions. A drum is connected to the door and mounted for rotation in response to movement of the door between its open and closed positions, the drum having a spiral groove formed in the outer surface for guiding a cable along the drum when the drum is rotated. A cable is connected to the drum and adapted to wrap around the drum in the spiral groove in response to rotation of the drum in one direction, and to unwrap from the drum in response to rotation in the opposite direction. A weight is suspended from the cable for applying a torque to the drum, and thus applying a force to the door, urging the door toward its open position. The radius of curvature of the spiral groove about the axis of the drum gradually decreases along the length of the drum so that the torque arm between the axis of the drum and the cable gradually decreases as the cable moves along the spiral groove for counterbalancing the variable forces urging the door toward its closed position. At the small end of the drum, the spiral groove preferably approaches the axis of the drum to reduce the torque arm to substantially zero when the door is in its open position. In one embodiment, a secondary cable is connected to a secondary drum having a conventional spiral groove, with this secondary cable being connected to the door for decreasing the torque exerted on the secondary drum as the door is moved toward its closed position. This secondary cable and drum permit the use of a smaller rate of change in the radius of curvature of the spiral groove in the primary drum than would otherwise be required. For safety purposes, a brake means may be connected to the drum for automatically locking the drum and preventing further movement of the door in response to a malfunction in the counterbalancing mechanism.

Patent Agency Ranking