WO1999035409A1

WO1999035409A1 - Locking arrangement for telescopically moving tubes

Info

Publication number: WO1999035409A1
Application number: PCT/AU1999/000003
Authority: WO
Inventors: Bruce Albert Anderson; David Rex Stone
Original assignee: Tubalco Manufacturing Pty. Ltd.
Priority date: 1998-01-07
Filing date: 1999-01-07
Publication date: 1999-07-15
Also published as: AUPP124098A0

Abstract

A locking assembly for telescopically moving tubes, the assembly comprising an outer tube (11), a collar (24) located at one end of outer tube (11), a slider mount on collar (24) that projects substantially radially away from collar (24), a slider (35) engaged on the slider mount so that it is able to slide along the slider mount, abutment means (51, 44) at each end of the slider mount to limit movement of slider (35), an inner tube (10) located within outer tube (11) and through collar (24) for telescopic movement with respect to outer tube (11), and locking means (50) acting between collar (24) and inner tube (10) to hold inner tube (10) with respect to outer tube (11), locking means (50) being operated by slider (35) to both disengage locking means (50) to thereby allow relative movement of inner and outer tubes (10, 11) and to re-engage locking means (50). Applications of the locking assembly include telescopic wands used with vacuum cleaning machines, tripod legs, or any other form of adjustable structure or support.

Description

"LOCKING ARRANGEMENT FOR TELESCOPICALLY MOVING TUBES" This invention relates to a locking arrangement for telescopically moving tubes, and in particular to an assembly for a locking arrangement, and to formations used on the telescopic tubes.

This invention will find many applications in respect of telescopic tubes which need to be moved from one locked position to another. Examples of applications include telescopic wands used with vacuum cleaning machines, tripod legs, or any other form of adjustable structure or support.

However, for clarity of description, the invention will be described in respect of its application to telescopic wands used with vacuum cleaning machines.

In this particular example, as with other applications, it is a requirement to provide a locking system which is simple in design and easy to assemble and operate.

Common locking arrangements between an inner and outer tube normally comprise a series of spaced indentations or recesses along a portion of the surface of the inner tube with a fitting secured to the outer tube that has an element that locates within the recess. When this element is physically held within the recess, the two tubes are locked with respect to one another. The fitting normally comprises a manually operated slide, which when pushed to a certain position, enables the element to lift clear of the recesses. This then allows the inner tube to slide with respect to the outer tube. The manually operated slide is spring-loaded, and will return to its locked position when released.

The recesses on the inner tube normally comprise a short channel formed into the surface of the inner tube with the longitudinal axis of the channel at right angles with respect to the longitudinal axis of the inner tube. Both the inner .and outer tube are normally made of either light gauge stainless steel, aluminium, or any other suitable material and the indentations can simply be pressed into the surface of the inner tube.

A common problem with existing locking arrangements is the extremely complex nature of the fitting. Several components are used both on the inner and outer surface of the outer tube in order to fix the fitting in place, and numerous other components are used to assemble the manually operated slide.

Another problem with the known locking arrangements is the inability of the tubes to resist compressive loading. The locking mechanism fails as a result of the excessive force applied by the element within the recess flattening the surface of the inner tube between adjacent recesses thereby allowing movement of the inner tube with respect to the outer tube. The side walls of the channels forming the indentation are normally inclined away from the vertical, and therefore generally have very little resistance to compressive loading. In order to overcome this problem, the locking arrangements need to be rigid and therefore robust to prevent flexing under load which allows lifting of the element and which in turn leads to flattening of the recesses.

It is an object of this invention to overcome the compressive loading problem referred to above, and to also provide a system which significantly simplifies the construction of the fitting used between the two tubes. Other advantages and benefits of the invention will become apparent from the following description.

In one aspect, the invention is a telescopic tubular assembly including: an outer tube, a collar located at one end of said outer tube, a slider mount on said collar that projects substantially radially away from said collar, a slider engaged on said slider mount so that it is able to slide along said slider mount, abutment means at each end of said slider mount to limit movement of said slider, an inner tube located within said outer tube, and through said collar, for telescopic movement with respect to said outer tube, and locking means acting between said collar and said inner tube to hold said inner tube with respect to said outer tube, said locking means being operated by said slider to both disengage said locking means to thereby allow relative movement of said inner and outer tubes and to re-engage said locking means.

The inner and outer tubes may be made from light gauge stainless steel, aluminium or any other suitable material including a moulded plastic.

The outer tube may have a cut-out at one end so that the slider mount on the collar can be positioned so that it extends through that cut-out.

Preferably, the arrangement of the cut-out and of the slider mount which fits into the cut-out is such that the slider is held in position when the collar is located in the outer tube. The slider may be arranged to engage a portion of the outer tube such as an end of the cut-out portion so that its movement is limited in that particular direction. In respect of the opposite direction, the collar may be provided with abutment surfaces which limit the movement of the slider in that direction.

The slider mount may be provided with longitudinal recesses or track surfaces, and the slider may be provided with inwardly directed longitudinal flanges which locate within the longitudinal recesses or track surfaces. This holds the slider onto the slider mount as well as allowing the slider to move on the slider mount. Preferably, the slider mount comprises an elongate projection parallel to the longitudinal axis of the inner and outer tubes and the cut-out is correspondingly shaped to receive the projection. Preferably, the cut-out is open at one end and enables the outer tube and collar to be pushed together. The cut-out portion may have inwardly projecting barbs which locate within corresponding recesses within the slider projection. The resilient nature of the outer tube enables the cut-out to spring slightly open so that the barbs locate within the recesses. Once in position, the collar is held with respect to the outer tube.

Additional fixing means may also be provided comprising inwardly directed tabs which locate in corresponding recesses within the collar. These tabs and recesses may be evenly spaced around the diameter of the outer tube to prevent rocking of the collar within the outer tube due to the application of asymmetric forces.

As with conventional arrangements, the inner tube is provided with a series of spaced recesses comprising channels which are formed across the tube at 90° to its longitudinal axis. A locking element comprising a cylinder or roller is preferably used to engage the recess. The slider track has an aperture within which the roller moves into and out of engagement with each of the recesses. The slider is provided with an abutment surface which holds the roller within the recess and prevents vertical movement thereby locking the two tubes together. It also has a recess that can be positioned over the aperture to allow vertical movement of the roller. When in this position, if force is applied to the inner tube, then the roller element is moved vertically so that it is fully clear of the recess. This then enables the inner tube to move with respect to the outer tube and when the desired relative position is obtained, by releasing the slider element, the roller is then able to drop into the next recess which aligns with the aperture.

Preferably, the slider is spring-loaded so that when it is released, the slider moves back to a position where the abutment surface is located over the roller and aperture. As an alternative, the slider projection may incorporate a resilient finger held at one end with respect to the slider projection. The free end may have a projection equivalent to the roller. The slider controls locking movement of the projection in a manner similar to the roller.

The inner tube is preferably designed so that it is unable to rotate with respect to the outer tube. One way to achieve this is to form a pair of spaced channels into the surface of the inner tube. The channels are parallel to the longitudinal axis of the inner tube and may extend along most of its length. Elongate projections may be formed on the internal surface of the collar that respectively locate within the channels so that rotation is prevented.

Preferably, the channels ate formed within the surface of a tubul.ar member having a circular cross-section. The tubular member may be a light gauge stainless steel, aluminium or other suitable material including a moulded plastic. In the case of a metal, the channels may be formed by any appropriate means including a pressing operation, a roll-forming operation or a combination of both. The elongate channels have an axis that is substantially parallel to the longitudinal axis of the inner tube, and which may be spaced by a distance which equals the width of the plurality of recesses into which the locking element may locate. The pressing of the channels into the outer surface of the inner tube results in the formation of the two spaced generally radial walls, with the remaining surface of the inner tube between the two channels forming the intermediate wall.

In the same operation, or in a later operation, recesses may then be formed across the surface of the intermediate wall so that the recesses are formed both in the intermediate wall and the two side w.alls. The advantage of this configuration is that, when compressive forces are applied to the assembly, the locking element will apply load in the recess which is resisted by the radially positioned walls. The configuration of the locking formation, and in particular the spaced radially positioned walls within which the recesses are formed, has significantly increased load bearing capacity by comparison to prior art recesses which are simply channels formed within the outer surface of a tube having a circular cross-section. This in turn means that other components can be constructed more lightly with simpler assembly as a result of the recesses having an improved load bearing capacity.

In order to further increase the load bearing capacity, the intermediate wall extending between the radially positioned walls may be flattened or comprised of substantially planar section.

In respect of both aspects of the invention, the inner tube may have projections formed in the end of the inner tube that locates within the outer tube that abut against the collar thereby preventing the inner tube disengaging from the collar and outer tube.

In order for the invention to be fully understood, a preferred embodiment will now be described. This embodiment will be described in relation to the invention's application to telescopic vacuum cleaner tubes. However, it should be realised that the invention is not to be confined or restricted to the precise features of this embodiment.

The embodiment is illustrated in the accompanying drawings in which:

Fig 1 shows a longitudinal cross-sectional view of a telescopic tubular assembly;

Fig 2 shows a transverse cross-sectional view of a telescopic tubular assembly; Fig 3 shows a longitudinal cross-sectional view of a telescopic tubular assembly with the slider pushed forward so as to release the locking means;

Fig 4 shows a perspective view of the collar located on the external surface of an inner tube prior to the outer tube being secured to the collar;

Fig 5 shows a perspective view of the end of the inner tube with the plunger fitting attached to the end of the inner tube;

Fig 6 shows a perspective view of the inner tube collar and outer tube prior to assembly; and

Fig 7 shows a plan view of the cut-out 20 in the end of the outer tube.

Fig 1 shows an inner tube 10 and an outer tube 11. The inner tube 10 is designed to telescopically slide within the outer tube 11. In this embodiment, the inner and outer tubes 10 and 11 are manufactured from light gauge stainless steel.

The inner tube 10 has a pair of spaced channels 12 formed along its length. The channels 12 comprise a pair of spaced and generally radial side walls 13 with an intermediate wall 14 extending between the side walls 13. A plurality of recesses 15 are formed along the intermediate wall 14. The recesses 15 also extend across the side walls 13.

The channels 12 are formed in the inner tube 10 which starts as a tube having circular cross-section. The channels 12 are formed by a pressing operation. The channels 12 have a right-angled cross-section with one of the surfaces of the channel comprising a side wall 13. In addition to a pressing operation, the channels 12 can be formed either by a drawing or roll forming. The recesses 15 can be formed in the same manufacturing operation.

The process of forming the channels 12 within the outer surface of the inner tube 10 result in the intermediate wall 14 maintaining the curved cross-section of the inner tube 10. The intermediate wall 14 may be flattened to remove this curvature to enhance the strength of the recesses 15 to prevent deformation when compressive load is applied to the assembled tubes 10 and 11.

Fig 5 shows a plunger 17 which is located in the end of the inner tube 10 that locates within the outer tube 11. The plunger 17 is shown in position on the end of the inner tube 10 in Fig 1. The end of the plunger has a flexible wall 18 which forms an air-tight seal between the inner and outer tubes 10 and 11.

Fig 7 shows the cut-out 20 that is formed into the end of the outer tube 11. The cutout 20 has a pair of barbs 21 and recesses 22 which are used for fixing purposes. Figs 4 and 6 show best the collar 24. The collar has a tubular body 46 that is fixed within the enlarged end 47 of the outer tube 11. Tabs 19 are pressed inwardly from the outer tube 11 and locate in recesses 23 to assist in locking the collar 24 to the outer tube 11. The inner diameter of the collar 24 is shaped to allow the inner tube 10 to be positioned within the collar and to slide relative thereto. The internal surface 25 of the collar 24 has a pair of elongate projections 27 that locate within channels 12. This prevents rotation of the inner tube 10 with respect to the collar 24.

The collar 24 has a slider mount 29 that projects from the tubular body of the collar 24. The slider mount 29 has longitudinal recesses that comprise channels 30 on either side of the slider mount 29. The slider mount 29 also has channels 31 on either side of the slider mount 29. At the end of the channels 31 there is a recess 32 and a projection 33 that are designed to be engaged by the barbs 21 and recesses 22 of the outer tube 11.

In order to assemble the inner and outer tubes 10 and 11 and the collar 24, the collar 24 is preferably first positioned over the inner tube 10. The end of the inner tube 10 is provided with a series of projections 48 (see Fig 5) formed in the peripheral edge of the end of the inner tube 10 which will abut against the collar 24, thereby preventing the inner tube 10 completely withdrawing from the assembly once the collar 24 is in position. The ends of the channels 12, which when formed extend to the end of the inner tube 10, may have a small section 49 of each channel at the end of the inner tube 10 pressed back to its original position to thereby form projections against which the collar 24 will abut.

The slider 35 illustrated in Figs 1, 2 and 3 is positioned on the slider mount 29 before the collar 24 is finally secured to the outer tube 11. The slider 35 has a pair of longitudinal flanges 36 which locate within the channels 30. The slider also has a central body 37 that locates within slot 38 in the collar 24. The slider body 37 has a recess 39 within which a spring 34 locates. It also has an abutment surface 40 and a recess 41.

The slider mount 29 has an aperture 42 within which a roller 50 locates. The aperture

42 opens on the inside surface 25 of the collar 24. The roller 50 in this embodiment is a cylindrical shape having a diameter of approximately 4 mm and a length of approximately 10 mm. The roller 50 is designed to locate within recesses 15 on the inner tube 10. The aperture 42 in the slider mount 29 is provided with side channels

43 which ensure that the roller is constrained to vertical movement with respect to the slider mount 29.

When the slider 35 is positioned on the slider mount 29, the abutment surface 40 is normally positioned over the aperture 42. In this position, the roller 50 is unable to move vertically, and is held in position within the recesses 15. This effectively then locks the inner tube 10 with respect to the collar 24. When the slider 35 is pushed so that it moves with respect to the slider mount 29 against the spring force, the recess 41 can be brought into alignment over the aperture 42 to thereby enable vertical movement of the roller 50. This then allows the roller 50 to lift sufficiently to clear the recesses 15 thereby allowing movement of the inner tube 10 with respect to the collar 24. In order to complete the assembly, the collar 24 is pushed into the outer tube 11. When the barbs and recesses 21 and 22 engage the recess and projections 32 and 33, the slider 35 is prevented from disengaging from the slider mount 29 as a result of abutment of the ledge -44 against the outer tube 11 at the end of the cut-out 20. The end of the slot 38 is a wall 51 that restrains the slider 35 at that end of the slider mount 29.

In use, the slider 35 is pushed forward so that the recess 41 aligns with the aperture 42. This enables the roller 50 to raise vertically so that it is clear of the recesses 15. The recesses 15 will tend to force the roller 50 vertically thereby enabling the inner tube 10 to move with respect to the outer tube. Provided that the slider 35 remains depressed in a forward position, then the roller 50 will pass over the recesses 15. When the slider 35 is released, the roller 50 will engage the next recess 15 that aligns with the aperture 42 thereby allowing the slider to move to its rearmost position with the abutment surface 40 located over the aperture 42. In this position, the roller 50 then locks the inner tube 10 from any further movement.

The channels 12 formed from the side walls and intermediate wall 13 and 14 will provide increased rigidity when compressive loading is applied to the inner tube 10.

As an alternative to a roller 50, the slider mount 29 may incorporate a resilient finger (not drawn) held at one end by the slider mount 29 with the free end comprising a projection that locates within the recesses 15. The slider 35 may be adapted to work in a similar manner as it does with respect to the roller 50. That is, an abutment surface may be provided to hold the finger against vertical movement so that the projection locks within the recess 15, and in a second position the finger may be allowed sufficient vertical movement so that the inner tube 10 can move with respect to the outer tube 11. It will also be seen from the above description that the locking formation comprises only a small number of components and is quickly and easily assembled. The invention has specific application to use with vacuum cleaner extension tubes, but will obviously have other applications.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A telescopic tubular assembly including: an outer tube, a collar located at one end of said outer tube, a slider mount on said collar that projects substantially radially away from said collar, a slider engaged on said slider mount so that it is able to slide along said slider mount, abutment means at each end of said slider mount to limit movement of said slider, an inner tube located within said outer tube, and through said collar, for telescopic movement with respect to said outer tube, and locking means acting between said collar and said inner tube to hold said inner tube with respect to said outer tube, said locking means being operated by said slider to both disengage said locking means to thereby allow relative movement of said inner and outer tubes and to re-engage said locking means.

2. A telescopic tubular assembly according to claim 1 further comprising a longitudinal cut-out in said outer tube at said one end, a portion of said collar located within said one end so that said slider mount at least locates partially in and projects out of said cut-out.

3. A telescopic tubular assembly according to claim 2 further comprising at least one barb on said outer tube within said cut-out, and said slider mount having at least one recess into which said at least one barb locates to hold said collar with respect to said outer tube.

4. A telescopic tubular assembly according to any one of the preceding claims wherein said slider mount has a longitudinal recess on each side of said slider mount, and said slider has a pair of inwardly directed flanges that respectively locate within said longitudinal recesses to enable said slider to move along said slider mount.

5. A telescopic tubular assembly according to any one of the preceding claims wherein the first of said abutment means comprises a portion of said outer tube.

6. A telescopic tubular assembly according to claim 5 wherein said portion of the outer tube is an edge within said cut-out.

7. A telescopic tubul.ar assembly according to either one of claims 5 or 6 wherein said slider mount has a recess extending parallel with the longitudinal axis of said collar with a wall spaced from said first abutment means that comprises the second of said abutment means.

8. A telescopic tubular assembly according to claim 7 wherein a spring is positioned between said slider and said wall, said spring urging said slider into a position where it holds said locking means in a locked position.

9. A telescopic tubular assembly according to any one of the preceding claims further comprising an aperture in said slider mount that extends through said collar, said locking means comprising a locking element located within said aperture and said inner tube having a plurality of spaced recesses, said locking element projecting through said aperture to locate within one of said recesses so that relative movement between said inner and outer tube is prevented while said locking element is held in said position.

10. A telescopic tubular assembly according to claim 9 wherein said slider has a first portion that prevents sufficient vertical movement to keep said locking element in its locking position, and a second portion, that is positioned over said locking element by moving said slider with respect to said slider mount, which allows sufficient vertical movement of said locking element to disengage from said recess.

11. A telescopic tubular assembly according to claim 10 wherein said first portion comprises a horizontal surface and said second portion comprises a recess in said horizontal surface.

12. A telescopic tubular assembly according to any one of the preceding claims further comprising a pair of spaced channels formed in said inner tube, said channels extending parallel to the longitudinal axis of said inner tube, and a pair of elongate projections on the inner surface of said collar that locate respectively within said channels to prevent rotation of said inner tube about its longitudinal axis with respect to said outer tube.

13. A telescopic tubular assembly according to claim 12 wherein said plurality of recesses are formed between said spaced channels.

14. A telescopic tubular assembly according to claim 13 wherein said locking element comprises a bar.

15. A telescopic tubular assembly substantially as herein described and with reference to any one of the accompanying drawings.