Screw lift

Elevator – industrial lift truck – or stationary lift for vehicle – Stationary lift for roadway vehicle or required component... – Having specific drive means for support

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Details

187136, 464 42, 74412TA, B66B 1104

Patent

active

049192361

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a screw lift comprising a lift car movably supported along an upright fixed screw and carrying a nut in engagement with said screw, and drive means including at least one electric motor for rotation of the nut on the screw and thereby driving of the lift car along the screw.
A number of different screw lift constructions of this type or similar are known since long. They have only proved to be useful to a limited extent and for quite particular purposes and are, in general, not particularly suitable for conveyance of passengers in houses and the like. The reason is a slow motion of the lift car, a transport height that is limited due to the screw, risk for appearance of destructable forces between the nut and the screw, when the lift car impacts an exterior obstacle, e.g. reaches the bottom, and a delicate and expensive design, generally for eliminating disadvantages of this type.
One object of the invention is to provide a screw lift which, by means of a simple and little cost and space requiring construction, permits a solution to the above and similar problems and thereby is well suited for use for personal conveyance in houses.
This object has been attained in that, in the screw lift according to the invention, the nut is rotateably journalled in a bearing and lubrication housing, and carries the lift car via a belt pulley driven by the motor, said belt pulley being disengageable from the nut when the lift car impacts an exterior obstacle.
A further object of the invention is to provide, in a screw lift of the kind indicated by way of introduction, where the drive means, comprises at least one electric motor provided with a drive circuit, control means for the drive of the lift, which fulfil the requirements on a modern lift for personal conveyance with respect to security, landing accuracy and so on, while maintaining a simple, cheap and little space requiring design of the lift plant in its entirety.
This object has been attained according to the invention in that, a pulse transmitter by sensing and/or determining the position of the nut on the screw is arranged to provide signals corresponding to the position, direction of movement and velocity of the lift car, and in that a control unit, in response to said signals and to manoeuvering signals transmitted from the lift car, is arranged to control said drive curcuit for operating the electrical motor as desired.
Preferred embodiments of the invention appearing from the subclaims involve optimum use of the basic ideas of the invention.
The invention shall now be described more closely with reference to embodiments shown on the attached drawings.
In the drawings
FIG. 1 is a simplified perspective view of one embodiment of the screw lift according to the invention,
FIG. 2 is a likewise partly simplified perspective view of the drive unit of the screw lift as seen obliquely from above and from the front towards the roof of the lift car of FIG. 1, with omission or cutting away of portions less essential to the invention for the sake of clearness,
FIG. 3 is a corresponding plan view of the drive unit
FIG. 4 is a section in the direction of arrows IV--IV in FIG. 3,
FIGS. 5 and 6 are views partly similar to those in FIGS. 3 and 4 illustrating an alternative simpler embodiment of a drive unit for a screw lift,
FIG. 7 is an axial section through the nut and the portions cooperating therewith,
FIG. 8 is a section in the direction of arrows XIII--XIII in FIG. 7, and,
FIGS. 9 and 10 schematically illustrate portions of the electric drive and control system of the lift, essentially in block diagram form.
The screw lift illustrated in the drawings includes a lift car 2. The lift car 2 is movably supported along an upright fixed screw 4, preferably with at least two parallel threads. More particularly this support includes guide beams 6 extending along the screw 4. FIG. 2 indicates how the guide beams 6 can be U-shaped and receive blocks 8 of teflone or the like, which are attached to the sidewall of the lift car at the rear end ther

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patent: 4128142 (1978-12-01), Satoh et al.
patent: 4375770 (1983-03-01), Druet
patent: 4440266 (1984-04-01), Kohler
patent: 4644811 (1987-02-01), Tervo

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