Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes linking support cable in drive-means
Reexamination Certificate
2000-05-08
2001-10-23
Lillis, Eileen D. (Department: 3652)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes linking support cable in drive-means
C187S254000, C187S262000, C187S259000, C187S266000, C254S338000
Reexamination Certificate
active
06305499
ABSTRACT:
TECHNICAL FIELD
The present invention relates to elevator systems and, more particularly, to a drum drive elevator system that requires minimal installation and operation space and that eliminates the potential of inadvertently driving past the top terminal.
BACKGROUND OF THE INVENTION
Known drum drive elevator systems typically involve “cotton reel” type drum and lifting rope arrangements where the rope is wound onto the drum with successive turns such that each length of rope is placed adjacent to the prior length to form a single layer of wound rope. Such systems are usually limited to single layer rope winding because of safety and rope life considerations. In situations where the elevator car must travel over a large rise, the length of the drum required to accommodate single layer rope winding becomes impractical. Because of the length of the drum in such instances, large variations in the rope path occur as the rope is wound along the drum. This may cause difficulty in the placement of guidance sheaves and may result in changing direction of forces imposed on the elevator car thereby affecting ride quality.
In typical elevator systems, lifting force on an elevator car is delivered from a sheave located above the car. Without additional means of control, the lifting force could continue to be delivered until the elevator car impacts either the ceiling of the hoistway or the sheave. Thus, there exists the potential in conventional elevator systems having the drive sheave or drum located overheard that the elevator car may be accidentally driven through the top terminal. Special precautions are ordinarily required to ensure that drive force is disabled when the elevator car moves beyond the top terminal level. In traction elevator systems, for example, a deceleration zone and safety equipment such as a rope brake are required, adding cost and space consumption.
Conventional drum and traction elevator systems usually require a large machine room to accommodate the overhead machine and components, including safety features. It is desirable to eliminate the need for a large machine room and its associated costs and building structure requirements.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a drum elevator system that requires minimal machine room space. It is a further object to provide a drum elevator system that has inherent safety features to eliminate the potential of driving through the top terminal. These and other inherent objects are achieved by the invention as described below.
The present invention elevator system utilizes a drum and rope system that allows multiple layers of rope winding around the drum. The arrangement eliminates the problems described above associated with rope path variation and ride quality, while increasing the practical limit for rise height. The present invention elevator system also ensures that the lifting force on the elevator car is reduced to zero at a short distance past the upper terminal level, thereby eliminating the over-rise problem described above. This loss of lifting force is inherently controlled by the sizing and spatial arrangement of the drum, car sheaves, a diverter sheave and the fixed hitch point of the belt. In the present invention the vertical positions of the drum and the fixed hitch point define the limit of the highest achievable vertical position of the elevator car. This feature eliminates the need for speed limiting or other safety features.
The present invention elevator system requires only a small machine room that can be located on the top terminal floor, avoiding the need for a separate structure and special building requirements. There is no requirement for hoistway space to accommodate a counterweight, as is required with conventional traction systems.
In another embodiment of the present invention, an elevator system utilizes a single drum drive positioned at the bottom of the hoistway, or in the hoistway pit, and is adapted to simultaneously wind two traction belts. Each traction belt is attached to and supports one side of the elevator car. One end of each belt is attached to the elevator car, and the other end of each belt is attached to the drive drum for selective winding to retract or release belt length, thereby controlling vertical movement of the elevator car. The positioning of the drum drive in the pit eliminates the need for a machine room or external structure for mounting the drive, while allowing sufficient space for the double-wound drum when the elevator car is in a raised position.
These and other advantages are apparent from the description provided below.
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Elevator Mechanical Design Principles and Concepts, Hanover Fair: Another New Idea from Contitech—Lifting Belts for Elevators.
Jones David W.
Kanzaki Yuji
Mori Toshimitsu
Nabetani Tadaaki
Shibasaki Shusaku
Lillis Eileen D.
Otis Elevator Company
Tran Thuy V.
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