Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Patent
1992-12-08
1994-08-23
Herrmann, Allan D.
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
74459, 182141, 187 25, F16H 2524, B66B 1104
Patent
active
053397045
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an arrangement in a screw lift, in which the lift cage or similar is carried by a nut rotatably provided on an essentially upright screw, the lift cage carrying a bearing means and a drive means for the nut.
2. Discussion of the Related Art
Conventionally, in such screw lifts, the screw hangs from an attachment at the uppermost end of a guide rod. This design is limited with respect to its lifting height, since the dead weight of the screw plus the lift cage with its load shall be carried by the screw. Furthermore the guide rod must be designed so as to be able to carry the above mentioned load plus dynamic additional loads at catching and braking operations.
SUMMARY OF THE INVENTION
The purpose of the invention is to provide, in a screw lift of the kind indicated above, an arrangement that admits an unlimited lifting height.
The above mentioned purpose has been attained in that, according to the invention, the screw is supported by several supporting braces attached thereto along the length thereof, and in that the nut has the shape of a spiral having turns, the pitch and axial thickness of which are adapted to the distance between the braces and the dimension of these in the length direction of the screw so as to enable the nut to pass freely past the braces by these passing between the turns of the nut during the passage.
The invention makes possible location of the screw resting with its lower end on a bed, the task of the braces being to support the screw against breaking under the moment imposed by the lift cage plus load. The task of a guide arranged in association with the screw is limited to guidance of the lift cage and taking up moments via lift cage guiding rolls running on the guide.
DESCRIPTION OF THE DRAWINGS
The invention will now be described more closely below with reference to some embodiments which are shown schematically on the drawings, of which
FIG. 1 a side view of screw and nut together with the driving portion in one embodiment of a screw lift according to the invention;
FIG. 2 is a view in the direction of arrows II--II in FIG. 1;
FIG. 3 is a partly sectional view essentially in the direction of III--III in FIG. 2;
FIGS. 4-6 in an elevational view, an end view and a side view, respectively, illustrate a section of a screw used with a screw lift according to the invention, the screw being attached to a guide by means of supporting braces spaced along the length of the screw;
FIG. 7 shows a view in the direction of arrows VII--VII in FIG. 5 of a detail of the screw and guide combination;
FIG. 8 in a heavily enlarged scale shows the encircled portion of the screw designated VIII in FIG. 6;
FIG. 9 shows a sectional view in the direction of arrows IX--IX in FIG. 8;
FIGS. 10 and 11, respectively, in the direction of arrows X--X in FIG. 8 show two embodiments of a connecting element included in FIG. 8;
FIG. 12 in a similar view as in FIG. 2 illustrates an alternative driving method for the drive nut;
FIG. 13 in an axial section through a portion of the nut in a further embodiment of the invention illustrates an alternative design of the supporting braces for the screw; and
FIG. 14 shows the brace according to FIG. 13 in a plan view.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the different Figures the same or similarly acting portions have obtained the same reference characters.
In the Figures the screw of a screw lift is designated 2, the screw lift being of the kind where the screw in an essentially upright position carries a lift cage which is indicated at 4 in some of the Figures. As noted in FIG. 4, the screw 2 with its lower end rests upon a base B. In a way to be described more closely below, the lift cage 4 carries a drive means, generally designated 6, and a bearing means, generally designated 8, for a nut 10 running on the screw 2.
The screw 2 is partitioned in mutually interconnected screw sections 2', 2", 2"' (FIGS. 4 and 6). Each screw section 2', 2" and 2"', respectively, is co
REFERENCES:
patent: 2527897 (1950-10-01), Todd
patent: 4279329 (1981-07-01), Gehron
patent: 4747320 (1988-05-01), Nilsson
patent: 4768621 (1988-09-01), Kunii
patent: 4919236 (1990-04-01), Karlsson et al.
Alimkak AB
Herrmann Allan D.
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