Elevator – industrial lift truck – or stationary lift for vehicle – Stationary lift for roadway vehicle or required component... – Having specific drive means for support
Patent
1981-10-07
1984-01-24
Dobeck, B.
Elevator, industrial lift truck, or stationary lift for vehicle
Stationary lift for roadway vehicle or required component...
Having specific drive means for support
340 21, B66B 136
Patent
active
044270950
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to systems for monitoring and controlling the positions of lifts, and for monitoring lift rope conditions, including overloading. The invention is described with particular reference to passenger lifts for use in buildings, but is of course applicable to lifts designed solely for lifting loads and also to lifts otherwise than in buildings e.g. on construction sites and in mine shafts.
In order to initiate appropriate motor and other control when operating lifts it is necessary to detect where the lift is. Accurate detection is necessary in order to initiate and control the deceleration of a lift as it reaches a desired floor position and in order to ensure that the lift stops with its floor level with the floor surrounding the lift shaft. It is also desirable accurately to detect where the lift is and which way it is going in order to provide a visual indication of position and direction both for passengers within the lift and for passengers waiting for the lift to arrive at the various floors. Such systems should also allow relevelling of the lift relative to the floors to compensate for example for stretch in the lift cables and movement in the building itself in which the lift is installed.
Two alternative approaches to monitoring and controlling lift position are known. The first of these is to construct conveniently in a lift motor room, a scale model of the lift in question. This may be driven by the main lift drive motor in such a way that the position of the lift in the model corresponds to that of the real lift in the shaft. By equipping the model with appropriate position sensors such as microswitches the lift itself may be controlled. The difficulties of building in small scale, e.g. 1:100, and the numerous mechanical moving parts make that system neither very accurate nor very reliable.
The alternative approach is to locate at spaced intervals down the lift shaft a variety of lift detection devices, usually of an electromechanical or photoelectric type. These are complex to instal, difficult to maintain (the lift generally has to be put out of action) and require substantial quantities of wiring. Additionally electromechanical devices such as uniselector switches are needed operatively connected to the various position detection devices in order to keep track of where the lift car is. This system is particularly complex if designed to operate properly even in the event of a transient power cut.
According to the present invention a lift position control system comprises, extending vertically down the lift shaft for substantially the whole of its height, an elongate code bearing member, having sequentially positioned along its length a sequence of coded units of information, and means co-operating with the elongate member and adapted to detect and decode the coded markings thereon and to derive therefrom information concerning the position of the lift and means for controlling the operation of the lift drive motor in dependence upon the positional information so detected.
Two alternative approaches may be employed: the coded elongate member may be suspended to extend substantially the whole height of the shaft and may be fixed in position. In this case the means for decoding the coded information on the elongate member preferably move with the lift car and are conveniently attached thereto. In an alternative, the decoding means may be fixed and the elongate member may be affixed to the lift car and move with it.
The elongate coded member may be made of any convenient material and the coding on it may be appropriately selected. The preferred material for the member is a flat strip e.g. of stainless steel. The preferred method of coding is to perforate the steel strip, notionally devided across its width into a plurality of tracks, perforations in the tracks corresponding to binary digits. By arranging successive coded numbers sufficiently closely along the elongate member, great positional accuracy of control can be achieved.
By way of example, one preferred type of e
REFERENCES:
patent: 3414088 (1968-12-01), Bruns et al.
patent: 3483950 (1969-12-01), Simpson
patent: 3963098 (1976-06-01), Lewis et al.
patent: 4203506 (1980-05-01), Richmon
patent: 4368518 (1983-01-01), Terazono et al.
Payne Reginald K.
Trett John
Dobeck B.
Duncanson Jr. W. E.
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