EP0326910A1 - Pushing jack - Google Patents

Abstract

This telescopic tube (10) consists of a first and a second continuous band (32, 36), wound respectively spirally and helically, with the turns of each band resting flat against one another in the retracted position of the tube. The turns of the respective bands are at right angles to one another. In order to lengthen the tube, the turns of the first band are spaced apart from one another, and the turns of the second band are inserted between the spaced-apart turns of the first band, so as to act as spacers for these latter turns. A mechanism is described here which produces the lengthening and the retraction of the tube, which is used especially as a pushing jack (10). <IMAGE>

Description

FIELD OF THE INVENTION

This invention relates to telescopic tubes, more specifically to be used as thrust cylinders.

STATE OF THE ART

Single acting telescopic hydraulic cylinders can be considered push cylinders. There is a practical limit to increasing the number of telescopic sections of such a hydraulic cylinder so that it remains as short as possible when in the retracted position. Consequently, such jacks, according to the desired stroke, occupy a minimum length which is still quite large, when retracted. When used as a lifting device, for example when several of these cylinders are used to lift a portion of the floor of a theater stage, it is necessary to make significant excavations in the ground to receive such cylinders in their portions lower ends.

It was discovered that in certain places, the water level in the ground does not allow such excavations. Therefore, there is a need for such specific applications for the theater and also for some other applications where the available space is limited, to provide a thrust cylinder which occupies a minimum of length when retracted from its stroke. elongation.

GOALS OF THE INVENTION

The general object of the present invention is to provide a telescopic tube, which, for a given extension stroke, occupies a minimum length when in the retracted position.

Another object of the present invention is to provide a telescopic tube used as a jack push which is of simple mechanical construction and which can exert a very high push force.

Another object of the present invention is that there is provided a thrust cylinder more particularly intended to be used as a lifting device or jack for lifting and lowering heavy loads.

SUMMARY OF THE INVENTION

The telescopic tube according to the invention comprises a first annular strip wound helically around a central axis with its turns transversely at right angles to said central axis and capable of assuming a retracted stowed position, with its turns lying flat against each other , and an elongated position with its turns spaced apart from each other in the direciton of said central axis, a second strip wound on itself, with its turns transversely parallel to said central axis, and capable of assuming a retracted spiral position with its turns engaged in each other and an elongated position with its turns forming a helix around said central axis and generally also radially spaced therefrom to form a tube, said first and second strips, when in the retracted position, being in positions respective as they are released from each other, spacing means for successively spacing the towers of said first strip, drive means for producing a relative rotation of said first strip and said spacing means around said central axis, and guide means for inserting the turns of the second strip between the spaced turns of the first strip, with the edges of the turns of the second strip abutting against the turns of the first strip, the second strip therefore constituting a spacer for these latter turns of the last strip.

Said spacing means preferably comprise support means forming a helix around said central axis, which can be inserted between two successive turns of said first strip and which abuts against one of said turns. Preferably, the second strip has an unconstrained radius of curvature approximately equal to that of the elongated tube. This allows easier insertion of the second strip between the turns of the first strip.

In one embodiment of the invention, said drive means comprise a motorized rotor capable of rotating around said central axis on a base, and surrounding the first retracted strip. Said support means are fixed inside said rotor and the retracted portion of said second strip is carried by said rotor on the outside thereof. Said guide means are carried on the outside of said rotor. The positioning means are carried by the turns of the first strip and can be engaged by the turns of the second strip to place these latter turns transversely to the turns of the first strip.

In a second embodiment, the two bands and the support means are arranged on the outside of the motorized rotor.

SHORT DESCRIPTION OF THE DRAWING FIGURES

• Figure 1 shows a front elevational view of the two push cylinders used as jacks for lifting a platform, as for a theater stage section;
• Figure 2 is a front elevational view, partially in vertical section, of a first embodiment of a push cylinder shown in an almost fully retracted position, the section being taken along line 2-2 of Figure 3 ;
• Figure 3 is a plan section of the cylinder Figure 2 thrust;
• Figure 4 is a partial longitudinal section taken along line 4-4 of Figure 2;
• Figure 5 is an elevational view, in section, longitudinal, developed, of the vertical strip in the inserted position between the two turns of a model of the horizontal strip;
• Figure 6 is a vertical section of a second model of thrust cylinder;
• Figure 7 is a plan section of the push cylinder of Figure 6; and
• Figure 8 is a sectional view of the arrangement of the vertical strip, with another model of horizontal strip.

In the drawings, like reference numerals refer to corresponding bodies.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

FIG. 1 shows two lifting jacks or jacks according to the invention, generally identified by the number 10, fixed to the ground 12 by their lower ends and to a platform 14 by their upper ends, the jacks 10 lifting or lowering the platform 14. The platform 14 can be a theater stage section, in which case there would be several jacks 10 for lifting these sections in a synchronized manner.

Referring to FIG. 2, each jack 10 of a first embodiment comprises an annular base 16 anchored to the ground 12, by means of L-shaped ground anchoring members, 18, and nuts 20, or any other suitable anchoring means.

A rotor 22, having the shape of a cylindrical body with a lower flange 24 extending radially outwards, can rotate on the base 16 by means of ball bearings 26 engaging grooves V-shaped annulars formed in the base 16 and in the lower rim 24. Therefore, the rotor 22 can rotate around the central axis of the base 16 and of the rotor 22. The peripheral edge of the lower rim 24 forms teeth 28 of toothed wheel all around, meshing with a drive wheel 30 (see FIG. 3) driven in rotation in both directions by a suitable motor, such as a reversible hydraulic motor, not shown.

A first annular continuous strip 32, which will henceforth be called the horizontal strip for the specific application shown, is wound helically and is of such an external diameter that it fits in the rotor 22 and in the base 16 The turns of this horizontal annular band can be successively lifted to create a space between them. The lower end of the horizontal strip 32 simply rests on the floor or the ground G, while its upper head end 34 is fixed under the platform 14 by means not shown.

A second strip 36, which will henceforth be called the vertical strip for the particular application described, is wound in a spiral, said strip being continuous, and when in stored condition, located in an annular storage box 38, arranged outside the rotor 22 and supported in rotation relative to said rotor by means of three L-shaped hooks 40 and also spaced from the relative angle point of view (see FIGS. 2 and 3) and fixed to the outside of the rotor 22 by bolts 42 and provided at their outer ends with a free roller 44 supporting the storage box 38 so as to allow its rotation. The hooks 40 can be fixed to the floor G or to the base 16.

As shown in Figure 2, it is obvious that the coil formed by the vertical strip 36 has a minimum diameter which is larger than the external diameter of the horizontal strip 32, so as to release the horizontal strip when the latter is almost completely stored, or when it is elongated. The radially outer end of the vertical strip 36 need not be fixed to the storage box 38. The radially inner end of the head of the vertical strip 36 passes through a rectangular opening 46 of the rotor 22, at the interior of this rotor, and is bevelled across the width, as shown at 48 in FIG. 2, to be fixed to the underside of the platform 40 by suitable means, such as the member 50 of I-shape in chopped off. The head end 48 fits between the radially inner edges of the member 50, the latter being bevelled along the length as for the head end 48 and being directly fixed under the platform 14. Consequently, the platform will remain level even if the vertical strip 36 projects upward along the propeller, as shown.

The rotor 22 includes on its inner surface a series of equidistant free rollers 52, each installed on a horizontal shaft 54, fixed to the rotor by a nut 56. The free rollers 52 are generally equidistant for a complete circle around the inside of the rotor 22 and arranged helically according to the desired pitch of the arrangement of the horizontal strip 32 and the vertical strip 36. As shown in FIG. 2, the head roller, 52A, is aligned longitudinally with the elongated opening 46, it - even inclined according to the step mentioned above. The trailing roller 52B vertically and spaced overhangs the head roller, 52A.

It will be understood that when the rotor is turned 22 along the arrows 58, as shown in Figure 1, in a direction to lift the platform 14, the free rollers 52 will roll under the radially outer margin of the turns of the horizontal strip 32 (see Figures 2 and 4), so as to space them out from an adjacent adjacent tower. At the same time, the vertical strip 36 penetrates the opening 46 and is guided radially inwards by the internal flat faces of the rollers 52 to be inserted between two adjacent turns of the horizontal strip 32. While the horizontal strip is raised 32 by rotation of the rotor, and consequently of the rollers 52, along a helix concentric with the central axis of the rotor, the vertical strip is gradually inserted between the adjacent turns of the horizontal strip, so as to gradually create a kind of tube or column. As shown in FIG. 2, the insertion of the vertical strip is facilitated, since the weight of the horizontal strip at the insertion point means that the latter constitutes a gap 60.

Means are provided for appropriately positioning the vertical strip between the adjacent turns of the horizontal strip. These means are shown more clearly in FIGS. 4 and 5. At the same time, these means allow the horizontal strip to be stored flat in the retracted position (see FIG. 2). These positioning means comprise a plurality of uprights 62 fitted in a greenhouse in a few of a series of corresponding equidistant orifices 64 formed in the horizontal strip 32, these orifices 64 being equidistant from the external peripheral edge of the horizontal strip 32. As shown in Figure 5, some of these uprights 62 are directed upward, while others are oriented downward; this in order to define both the top edge and the bottom edge of the vertical strip 36, this strip abutting against said amounts.

Some of these orifices 64 will not have uprights, so as to be able to receive the uprights of the next adjacent turn of the horizontal strip when the latter is in the retracted position, the projecting portion of the uprights 62 being no longer than the 'thickness of the horizontal strip.

In this way, the flat storage of the horizontal strip is obtained to store it in a minimum of height. As shown in FIG. 4, the arrangement of the two adjacent turns of the horizontal strip 32, with one turn of the vertical strip 36 being inserted between them, forms a substantially L-shaped section. The resulting arrangement is very solid and can bear a very large load, although it remains very stable transversely to its central axis. Depending on the length of the two bands 32 and 36, the thrust cylinder of the invention can have a very long stroke compared to its length when the two bands are in the retracted position.

Preferably, the vertical strip is pre-wound so as to have, when unstressed, a radius of curvature roughly equal to that of the assembled tube. This facilitates the correct insertion of the vertical strip between the turns of the horizontal strip.

The magazine or the box 38 is free to rotate around the axis of the tube to allow the insertion of the vertical strip and its removal despite the resulting variation in the internal diameter of the coil formed by the vertical strip of the box 38.

The second embodiment of the invention, and the preferred one, is shown in FIGS. 6 and 7. Also, FIG. 8 shows the preferred arrangement of the positioning means for positioning the vertical strip transversely and centrally with respect to the horizontal strip. The positioning means, shown in FIG. 8, are intended to replace the positioning pins 62 inserted in the orifices 64 of the horizontal strip 32, as shown in FIG. 5. The improved positioning means simply consist of a continuous groove upper and in a lower continuous groove, 70, formed in the opposite main faces of the horizontal strip 72. The grooves are arranged centrally of the width of the horizontal strip 72 and are coaxial and coextensive there. Consequently, the grooves 70 serve to receive the longitudinal edges of the vertical strip 74 in order to appropriately position and retain the latter transversely to the horizontal strip 72.

This modified arrangement can be used with the apparatus of Figures 1 to 4 as well as with the apparatus shown in Figures 6 and 7. The telescopic tube shown in Figures 6 and 7 comprise a base 76, of cylindrical shape, fixed to a ground plate, 78. A rotor 80 is supported so as to be able to rotate on the cylindrical base 76 by a ball-bearing arrangement, 82. The rotor 80 comprises a cylindrical wall 84 fitted tightly to an end disc 86 .

The rotor 80 is motorized by a motor (not shown) via a chain 88 with toothed wheel, driven by a gear wheel 90, the shaft 92 of which is fixed below the disc 86. The chain 88 with toothed wheel passes by openings 94 formed in the cylindrical base 76. The numerous turns of the horizontal strip 72 are stored, when the strip is in the retracted position, on a flange 96 projecting radially outward from the base 76 and fixed to it this. Therefore, the horizontal strip 72 is wound on the outside of the rotor 80.

A plurality of rollers 98 are installed on the rotor 80 near its upper edge outside of said rotor around axes directed radially downwards defined by retaining bolts 100. The rollers 98 are of frusto-conical shape so as to support one revolution of the horizontal strip 72 in a transverse horizontal position orthogonal to the central axis of the rotor 80. Each roller 98 has a bevelled edge 102 for engaging the longitudinal inner edge of the horizontal strip 72 and for centering this strip relative to the rotor.

The rollers 98 are arranged helically by making a complete turn around the rotor, with the lower head roller identified by 98A and the upper trailing roller identified in 98B relative to the rotation of the rotor when the column or the tube is being 'be raised.

The vertical strip 74 is wound into a reel, identified by 104, which is housed in a store or annular box 106 installed freely and so as to be able to rotate on support wheels, 107, 108, and 109 carried by raised arms 110 fixed at their lower ends to the rim 96 towards the outside of the horizontal strip 72. The annular magazine 106 is of a minimum diameter larger than that of the horizontal strip 72, so that the latter can pass freely through the magazine 106. The magazine is installed for free rotation around the central axis of the tube (or column). The vertical strip 74 is pre-wound or pre-formed to have a radius of curvature, when in an unconstrained condition, approximately equal to the diameter of the tube (or column) when the latter is arranged. The outermost turn of the reel 104 is taken to the top of the magazine and guided to move radially inward along a helix to be inserted between the two adjacent turns of the horizontal strip 72, the vertical strip being guided by a guide roller 112 (see FIG. 7), which is carried so as to be able to rotate by a hook 114 fixed to the rotor 80). The roller 112 can rotate around an axis 116, which is parallel to the central axis of the rotor 80, and the roller is applied against the outer face of the vertical strip 74 to compress it for insertion between two adjacent turns of the horizontal strip 72.

A rod 118 is also fixed to the rotor 80 and elongates radially towards the outside of the latter to be applied against the top of the coil 104 in a position immediately before the outermost turn of the coil begins to move up. This rod 118 is used to return the turns of the vertical strip 74 to the appropriate stored position in the magazine 106 when the column is retracted. The guide roller 112 firmly displaces the vertical strip 74 so that it engages the grooves 70 of the adjacent turns of the horizontal strip 72.

The highest end of the column can be defined by a push plate 120, which is fixed to the uppermost turn of the vertical strip 74, this last turn being bevelled so that the plate 120 is orthogonal to the 'central axis of the column (or tube).

Claims (17)

1. A telescopic tube comprising a first annular strip wound helically around a central axis with its turns transversely orthogonal to said central axis and capable of assuming a retracted position stored with its turns lying flat against each other, and an elongated position with its towers spaced from each other in the direction of said central axis, a second strip wound on itself, with its towers transversely parallel to said central axis, and capable of assuming a retracted spiral position with its towers inserted one into the other others and an elongated position with its turns forming a helix around said central axis and generally also radially spaced therefrom to form a tube, said first and second strips, when in the retracted position, being in such respective positions that they are separated from each other, spacing means for successively spacing the towers of said first strip, drive means for producing a relative rotation of said first strip and said spacing means around said central axis, and guide means for inserting the turns of the second strip between the spaced turns of the first strip, with the edges of the turns of the second strip abutting against the turns of the first strip, the second strip therefore constituting a spacer for the turns of the first strip. 2. A telescopic tube as defined in claim 1,
characterized in that said spacing means comprise support means constituting a helix around said central axis, capable of being inserted between the two successive turns of said first strip and abutting on one of the last mentioned turns. 3. A telescopic tube as defined in claim 2,
characterized in that said drive means comprise a motorized rotor capable of rotating around said central axis on a base, said support means and said guide means being installed on said rotor, and further comprising an annular magazine containing the retracted portion of said second strip, coaxial with said central axis and able to freely rotate relative to said rotor and to said base. 4. A telescopic tube as defined in claim 3,
and used as a lifting device, said central axis being generally vertical. 5. A telescopic tube as defined in claim 3,
characterized in that said support means comprise a series of rollers carried by said rotor, in the path of said first strip and arranged along a propeller extending over at least one full turn around said central axis, said rollers being capable of engage the turns of said first strip to move it. 6. A telescopic tube as defined in claim 1,
further comprising positioning means carried by the turns of the first strip and which can be inserted into the turns of the second strip, for positioning these latter turns transversely to the turns of the first strip. 7. A telescopic tube as defined in claim 6,
characterized in that said positioning means comprise pins projecting from the surface of the turns of the first strip, said pins projecting generally also spaced from the turns of the first strip and capable of engaging an edge portion of the turns of the second bandaged. 8. A telescopic tube as defined in claim 7,
characterized in that a first series of pins protrude from one face of said first strip, and in that a second series of pins protrude from an opposite face of said first strip, so that the turns of the second strip are engaged by said pins on their two longitudinal edges. 9. A telescopic tube as defined in claim 8,
characterized in that said first strip further comprises a series of openings formed therein, opposite said pins, in order to receive them when the turns of the first strip are in the retracted position, lying flat one on the other on the others. 10. A telescopic tube as defined in claim 6,
characterized in that said positioning means comprise a groove made in at least one face of said first strip coaxially and coextensive with it and intended to receive a longitudinal edge of said second strip. 11. A telescopic tube as defined in claim 10,
wherein said positioning means further comprises a second groove formed on the opposite face of said first strip coaxially and coextensively to said first strip, the two grooves being made centrally on said first strip, said second groove being intended to receive the other edge longitudinal of said second strip. 12. A telescopic tube as defined in claim 3,
wherein said second strip and its magazine are arranged radially outside said first strip. 13. A telescopic tube as defined in claim 12,
where said rotor is placed between said first strip and said magazine with the second strip inside. 14. A telescopic tube as defined in claim 13,
wherein said support means comprise a series of rollers carried by said rotor inside of it in the path of said first strip and arranged helically through at least one full turn around said central axis, said rollers supporting one turn said first strip for moving said tower outside an adjacent tower when said rotor rotates, and said guide means comprising an opening formed in said rotor and through which said second strip passes radially inward from said magazine , each roller having a radially inner face which forms an additional part of said guide means by pushing said second strip radially inward and maintaining said second strip over one revolution of said first strip. 15. A telescopic tube as defined in claim 12,
wherein said rotor is placed inside said first strip and said support means comprise a series of rollers carried by said rotor outside of it in the path of said first strip and arranged helically for at least one revolution complete around said central axis, said rollers supporting a revolution of said first strip for moving said revolution outside an adjacent revolution when said rotor rotates, said guide means comprising a guide roller carried by said rotor on the outside of the latter and engaging the radially outer face of said second strip to produce its insertion radially inward between two spaced turns of said first strip. 16. A telescopic tube as defined in claim 15,
wherein said positioning means comprise grooves formed in the two opposite main faces of said first strip, said grooves being coaxial and coextensive with said first strip and made centrally therein, said grooves being intended to receive the longitudinal edges of said second strip for retaining it centrally to said first strip. 17. A telescopic tube as defined in claim 16,
wherein said second strip has, when unconstrained, a radius of curvature approximately equal to that of the assembled tube.

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