Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes gear on support mating with stationary rack or chain
Reexamination Certificate
2002-03-06
2004-06-29
Lillis, Eileen D. (Department: 3652)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes gear on support mating with stationary rack or chain
C187S250000, C187S271000, C182S141000, C074S424600
Reexamination Certificate
active
06755283
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of Invention
The invention is related to the lifting appliance of elevators, and more particularly to a spiral propeller for elevators by making use of the spiral lifting mechanism. The propeller provides a safe lifting mode, which can be widely applied in multiple lifting systems such as lifts, elevators and etc., and increase the security performance of the lifting system to a large extent.
2. Description of Related Arts
Since the invention of the first elevator by Otis, elevators have evolved into a titanic industry gradually with the further development of technologies and people's increasing demands. The applications of elevators have become more and more widely, and have been warmly welcomed by people, especially those of developed countries with tremendous population and scarce geographical resources. Furthermore, elevators have become a must for high buildings.
At present, the elevators of vertical lifting, especially those elevators carrying people and goods in high buildings, are still employing the steel rope system for their lifting mechanism, i.e., the top of the elevator is fixed with the steel ropes to haul the steel ropes of the elevator, the steel ropes are led out from the top of the elevator, pass upwards through two pulleys set up on the guide bracket, then run downwards to the traction block for connection. During lifting, power electric motors are used to haul it for ascending or descending. The mode brings forward very rigorous demand on the steel ropes, pulleys and the support bars of pulleys, especially when the lifting elevation is very high.
Viewed from the process, the components mentioned above are the most important parts to bear weight. The steel ropes shall bear the weight of the elevator compartment itself, as well as the weight of the passengers or goods carried by the compartment. The steel ropes transfer the born weight to the pulleys, which will forward the force to the guide bracket via the pulley shafts, and the shafts deliver the force to the ground. The most important parts bearing weight are the pulleys and the pulley brackets except for the steel ropes. What's more, the bearing point for the weight of the compartment and the passengers and goods the compartment carries concentrates on the minor contact surface between the pulleys and the steel ropes, which is highly concentrated.
Firstly, as far as steel ropes are concerned, the pulling force born by the cross section of the unit steel rope is quite limited due to the manufacturing techniques at present, in addition, there exists the problem of fatigue for steel ropes. Steel ropes have to possess certain tenacity and sufficient radial distance, so as to ensure their strength, usually, a group of steel ropes is adopted to form the ropes to achieve this purpose. For the elevators in high buildings, the steel ropes bear the maximum pulling force when they start to ascend, especially for high-speed elevators, though the pulling force born during normal running is not so strong, the pulling force they bear during sudden ascending will be far stronger than the force during normal operation, as a result, the quantity of the steel ropes must be increased to bear the pulling force. The negative impact brought forward is obvious, i.e., the weight of the group of steel ropes has to be greatly increased, which will certainly increase the burden of the steel ropes. For the high buildings with many stories, the weight of the steel ropes is often larger than that of the elevator compartment.
At the same time, the aging of steel ropes remains a major difficulty, which results in two aftermaths: first, the steel ropes will be lengthened. Elevators have to be used frequently for a long time, after a period of time, the steel ropes will gradually age, and their tenacity will decrease. It is because of long-term weight bearing, the steel ropes will be slowly pulled lengthened under the influence of exterior force, which will lead to errors in the distance between the elevator compartment and the story it stays at. To avoid the unnecessary errors and the accidents that may happen due to the errors, it is necessary to perform periodic check, and get rid of the lengthened steel rope. Once the rope got rid of reaches a certain length, the steel ropes must be replaced, so as to avoid the ill effect of breaking of the steel ropes due to the decrease of tenacity and strength. Secondly, the steel ropes will break. After the aging of steel ropes, the strength will decrease, as well as the capability in bearing weight. Steel hawsers are made of many steel ropes, and each rope features different longevity and fatigue index due to the manufacturing characteristics and the materials of its own, and that even prevails in the same steel ropes made of the same batch of materials. Besides, the strength and the tenacity vary with the changes of the locations of the steel ropes themselves. At the same time, the points between different steel ropes and between different parts of the ropes vary with the stresses of different causes. If steel ropes are used too long, the steel rope with weaker strength and tenacity, or a part of the rope, will crack or even break caused by the unbearable weight. Once a rope breaks, the stresses of other steel ropes will also change with it, which may result in the breaking of the whole steel hawser, thus triggering major accidents. Because the steel ropes are very long, it is difficult to determine the location that may result in accidents, the only way out is to perform periodic and across-the-board check, which will usually increase the costs for repair and maintenance.
Secondly, the current technique adopts pulleys to make steel ropes slide upward and downward, the weight bearing point for the pulleys is limited to the minor contact surface of the arc shape, as a supporting object, the surface bears too much weight, which is subject to damage or skidding; the pulleys transfer the force to the pulley supporting bar, at the same time, the supporting bar will also bear tremendous pressure, with relatively single stress surface, and it is difficult to mend it in the case of damage, which will result in rather serious accidents.
Thirdly, the power of the elevator lifting system mentioned above is provided by the additional electric motor. When the electric motor fails or there is a sudden power blackout, the elevator will no longer work without power, which will surely trap the passengers within the elevator compartment, at the time, the people trapped in the compartment will have to ask for help from people outside the compartment, otherwise, there will be danger for them. Psychological harm will be done even after they escape. In case the elevator compartment is suspended between the upper and the lower stories, the rescue task will become extremely difficult. Therefore, the problems mentioned above must be watched out at any time, which will certainly impose much pressure on the repair and maintenance of the elevators.
Fourthly, there is considerable difficulty and risk during elevator installation. The steel hawser is the most important part for the lifting elevator, and the installation of steel hawsers have to depend on the guide bracket; as a result, guide brackets have to be first made prior to installation of steel hawsers. The installation of guide brackets is performed in the air manually, which will pose dangers to installation workers. At the same time, the steel hawsers have to be first threaded through the top of the guide brackets for installation, after which the hawsers will be pulled down. The space for elevator installation is quite limited, and extreme care must be undertaken during installation, otherwise, the heavy steel hawsers will damage other equipment, or even the installation workers.
To keep the normal running of the elevators, and to guarantee the safety of passengers, frequent maintenance and repair must be undertaken for the elevators mentioned above. Despite the fact that may equipment manufacturers today
Chan Raymond Y.
David and Raymond Patent Group
Lillis Eileen D.
Tran Thuy V.
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