Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes control for power source of drive-means
Reexamination Certificate
2000-06-21
2001-11-20
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes control for power source of drive-means
C187S359000
Reexamination Certificate
active
06318505
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device and a method for preventing vertical displacements and vertical vibrations of the load carrying means of vertical conveyors while they are stopped at landings, achieving the desired effect by the load carrying means being held fast on its guiderails during landing stops by means of frictional engagement, this frictional engagement being released in the presence of a corresponding control command.
The following description relates to passenger- or freight-elevators that represent a special type of vertical conveyors. The designation of the components therefore corresponds to the technical terms of the elevator field. For example, the load carrying means is designated as elevator car or car.
The European patent 0 346 195 discloses an electromagnetically actuated caliper which is designed inter alia to bind the car or counterweight of an elevator to its respective guiderail by means of frictional engagement. The brake has two double-arm levers with a common joint at their mid-point whose shaft is fastened to the car or counterweight. The gripping arms of the levers are lined with brake linings and embrace the tongue of the guiderail of the car or counterweight. The opposite, driving arms of the levers are held apart by a compression spring which gives rise to the gripping force between the brake linings and the tongue of the guiderail at the other end of the levers. Concentric to the compression spring which pushes the ends apart there is a pull-type electromagnet which, when current flows through it, overcomes the force of the compression spring and thereby opens the brake.
The disclosed braking device is particularly intended as a holding brake for counterweights or cars of elevators driven by linear motors, and the patent claims relate mainly to the embodiment of an integral damping element to prevent switching jolts and switching noises being caused by the pull-type magnet.
In elevator installations with large travel heights, cars hanging on suspension means such as, for example, wire ropes or flat belts have the disadvantage that when stopping at a landing they undergo relatively large vertical displacements whose cause is the stretching or contraction of the elastic suspension means due to changes in load. Such changes in load in the car are caused by passengers entering or leaving, or by transportation equipment being put into or taken out of the car. If the vertical displacements exceed a variable limit value, the drive usually executes a compensating movement until the surfaces of the car floor and landing floor are again at the same level. Depending on the type of change in load, several such compensating procedures may be necessary during a stop at a landing.
Furthermore, while stopped at a landing, such elevator cars are susceptible to vertical vibrations caused by the stopping process, changes in load, or the level-compensating procedures described above. Vertical displacements and vibrations of the car can cause passengers to experience unpleasant sensations or even alarm. Moreover, if the surfaces of the car floor and hoistway door sill are not at exactly the same level, this can lead to accidents caused by passengers stumbling as they enter or leave the car.
The situation described can be improved by holding the elevator car fast on its guiderails by frictional engagement.
SUMMARY OF THE INVENTION
The purpose of the present invention is to create a car braking device which solves the problems concerning vertical displacement and car vibrations described above without impairing the quality of ride, and particularly without causing a jerk when the brake opens for the car to continue its travel.
To ensure that there is no jerk when travel commences, when using a car braking device for the purpose described, the car-side suspension means (suspension ropes, suspension and driving belts, or similar elements) should be pre-tensioned to the load which will occur after the brake is opened, which is the case if a drive unit which can be regulated with respect to torque and rotational speed pre-tensions the car-side suspension means via the traction sheave each time before travel commences, so that the braking device is completely relieved before it is opened. For optimal fulfillment of this requirement the drive regulator must have suitable information concerning the load status on the car braking device.
Measuring the holding forces directly on the car braking device is advantageous because this makes it possible to register and compensate the holding forces actually present and because all indirect methods of relieving the brakes are subject to a number of sources of error.
Installation and use of the car braking device with integrated registering of the holding forces according to the invention has a number of important advantages. The first is that perfect relief of the brake before further travel commences is not effected by a pre-tensioning torque being generated by regulation of the drive unit and calculated from the torque registered when stopping and the difference in load measured during the landing stop; instead, it is effected by this torque being continuously increased by the drive unit before travel commences until a measuring bridge formed by the load-measuring sensors of the car braking device is in balance, i.e. the car braking device is perfectly relieved. With this method, deviations due to frictional effects, or resulting from errors in measuring the load in the car, and from inaccuracies in generating a torque corresponding to a calculated reference value, are ruled out.
Secondly, its use makes it possible to dispense with the relatively costly measurement of the load in the car, because the load in the car can be sufficiently accurately calculated from the torque on the drive unit before stopping and the change in load on the car braking device during the landing stop, the weights of the car, counterweight, and—depending on the position of the car—ropes being included in this calculation.
Thirdly, the car braking device according to the invention can replace the usual holding brake on the drive unit, although operation with both braking devices is possible.
Because the car braking device registers the holding forces in the upward and downward direction, the regulable drive unit has enough information available in all possible load situations to completely relieve the car braking device before travel continues and thereby to enable jerk-free starting. Registering the holding forces in the upward and downward direction is necessary for two reasons. If the elevator is operated with a holding brake on the drive unit, the car braking unit is loaded in opposite directions depending on whether passengers enter or leave. If operation is without a holding brake on the drive unit, the direction of load on the car braking device depends on whether the weight of the car and its momentary load is greater or less than that of the counterweight.
Integration of the measuring elements into the car braking device itself permits this device to be fastened onto the car in a simple, sandwich-like manner in combination with other car components, and to be electrically connected without problem.
Actuation of the brake levers of the car braking device by a stroke-imparting mechanism acting via a toggle mechanism has the advantage that the force of the stroke-imparting mechanism is amplified many times by simple means, and that in the braked status a continuation of the holding force of the stroke-imparting mechanism is not required. For this reason, and even taking account of power outages, stroke-imparting mechanisms can be used which have no pre-tensioned springs and operate with briefly activated closing and opening strokes such as, for example, a solenoid acting in both directions and having limited switch-on time.
An important advantage of this invention is that in the future, when use is made of suspension means made of synthetic fibers (e.g. aramide fiber ropes or flat belts), the problems in relati
Inventio AG
MacMillan Sobanski & Todd LLC
Salata Jonathan
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