GB2063352A

GB2063352A - Clamp for telescopically slidable elements

Info

Publication number: GB2063352A
Application number: GB8035168A
Authority: GB
Original assignee: Jani Jack Ltd
Current assignee: Jani Jack Ltd
Priority date: 1979-10-31
Filing date: 1980-10-31
Publication date: 1981-06-03
Also published as: GB2063352B

Abstract

A clamp for telescopically slidable tubes (26, 34) comprises inner and outer tubular members (2, 4), the inner member (2) having a series of resilient axial fingers (8) with pads (10) that project through apertures (36) in the outer telescopic tube (34). The outer member is rotatable relative to the inner member whereby the pads are pushed further into the apertures by cam means (20) on the outer member to engage the inner telescopic tube (26) and so clamp the tubes together. A stop (not visible) limits the relative rotation of the members (2, 4). The inner and outer members (2, 4) are snap-fitted together and the outer member overlies the fingers (8) to prevent withdrawal of the pads from their apertures, so that the device remains permanently mounted on the outer tube. <IMAGE>

Description

SPECIFICATION Clamping devices and telescopically slidable elements having such devices This invention relates to clamping devices for telescopically slidable elements, e.g. forming implement handles for such articles as mops or parts of collapsible furniture or other structures such as garden umbrellas, and to telescopically slidable elements provided with clamping devices.

One known form of clamping device comprises inner and outer concentric tubular members through which the telescopic elements pass, the inner member being slotted to provide a series of axially extending fingers and the outer member having a conical inner face that bears on those fingers, the two members being able to be interengaged by a screwthread to be axially displaceable relative to each other so that the conical surface urges the fingers inwards to clamp the telescopic elements together. This arrangement is relatively expensive to produce and in many instances is not very convenient to use.

According to one aspect of the present invention, there is provided a clamping device for a pair of telescopically slidable elements, the device comprising inner and outer members arranged to be mounted on one of the elements and being relatively moveable between opposite end positions while being retained in engagement with each other, in the movement to one of which positions co-operating means on the members are displaced to lock the elements together axially, and in the other said end position the elements are telescopically slidable relative to each other.

Such an arrangement is relatively simple to operate, since it provides positive positions for both the operative and inoperative state of the device while the members of the device remain permanently interconnected in either state.

According to another aspect of the invention, there is provided a clamping device for a pair of telescopically slidable elements, the device comprising inner and outer members arranged to be mounted on one of the elements and to be displaceable relative to each other between alternative angular positions in one of which the elements are axially locked together by the device and the other of which the elements are telescopically slidable. By the use of cam means or the like, it is possible to achieve the required result with a limited angular movement so that clamping can be effected easily and speedily.

More particularly, a clamping device according to the invention may comprise inner and outer tubular members of resilient plastics material axially secured together, the inner member having means arranged to fix it to the outer telescopic element and to engage the inner telescopic element, there being cam means on the outer member operable to apply pressure to said engagement means of the inner member to cause the inner member to clamp the inner telescopic element and thereby lock both elements together, said cam means being arranged to be brought into operation by relative rotary movement between the members, there being a movement of less than one complete revolution between the operative and inoperative states of the cam means.

An embodiment of the invention will be described in more detail with reference to the accompanying drawings, in which: Fig. 1 is an end view of an inner member of the clamping device according to the invention, Fig. 2 is an axial view of the inner member of Fig. 1, partly sectioned along the line Il-Il, Fig. 3 is an end view of an outer member of the clamping device, Fig. 4 is an axial section along the line IV--IV in Fig. 3, Fig. 5 is a view partly in section of one end of an outer tubular element onto which the locking device is to be fitted, and Figs. 6 and 7 illustrate the clamping device assembled with a pair of telescopic tubes, Fig. 6 being an axial section on the line VI--VI in Fig. 7 and Fig. 7 being a transverse section on the line VIl-VIl in Fig. 6.

Referring to the drawings, the clamping device consists of inner and outer concentric members 2, 4 each integrally moulded from a resilient plastics material, e.g. polypropylene or nylon, and it is shown in Figs. 6 and 7 mounted on a pair of telescopic tubes 34, 26 to secure the tubes 34, 26 together releasably.

The inner member 2 is shown in more detail in Figs. 1 and 2 and has a cylindrical end part 6 from which four equally spaced fingers 8 project substantially axially but tapering slightly inwards towards the opposite end of the member 2. The fingers 8 are formed as cylindrical segments and near their free ends remote from the end part 6 each has an inwardly extending projection or pad 10.

The outer member 4 shown in detail in Figs. 3 and 4 comprises a cylindrical sleeve 14 having an inwardly projecting annular rim 16 at one end forming a concentric aperture 1 8. The inner surface of the sleeve 14 at that end has four equally spaced flats 20, the spaces between them being substantially equal to the width of the fingers 8. At one side edge of one of the flats 20 there is an inwardly projecting stop rib 28 that extends axially along the length of the flat 20. The end of the outer member 4 remote from the flats 20 has a small lip 32 inwardly protruding around the entire inner periphery of the sleeve 14. The outer surface of the member 4 has a series of axially extending ribs 30 to allow the member 4 to be firmly gripped.

Before assembly of the device on the telescopic tubes, one end of the outer tube 34 has four rectangular apertures 36 (Fig. 5) cut in it, slightly larger than the pads or projections 10 of the inner member 2. To assemble the device, firstly, the inner member 2 is pushed over the end of the outer tube 34 with the end part 6 leading, until each of the projections 10 springs into one of the apertures 36. The inner member 2 is thereby positively located on the end of the outer tube 34.

The outer member 4 is then pushed over the inner member 2 with the lip 32 leading. As the fully assembled position is reached, the lip 32 snap-fits over the edge of the end part 6. Both members 2 and 4 are then axially locked together securely and the device is held permanently mounted on the outer tube 34 because the outer member 4 prevents the projections 10 being lifted from the apertures 36. While the device is in an inoperative position the inner telescopic tube 26 can be inserted into the outer tube, the aperture 18 in the outer member providing a free sliding fit for the inner tube and the projections 10 bearing lightly on it.

The device is operated by holding the outer tube 34 with one hand while rotating the outer member 4 with the other through an angle of some 45 between opposite end positions defined by the engagement of the stop rib 28 with one or other of the two fingers 8 between which it is located. Like the outer member 4, the outer tube 34 may be ribbed to improve the grip. In the position shown in Fig. 7, the rib 28 abuts the finger on its right-hand side and so limits the rotation of the outer member to the position in which all the fingers 8 are located in the spaces between the flats 20 and the clamping device is therefore inoperative. The inner tube 26 can be slid freely in and out of the outer tube 34.

By rotating the outer member 4 anticlockwise from the position shown in Fig. 7, until the stop rib 28 abuts against the finger 8 on its left-hand side, the flats 20 are brought over the fingers 8 and acting in the manner of cams urge the pads or projections 10 against the inner tube 26 to clamp the inner tube 26 relative to the outer tube 34.

The dimensions of the device are such that the clearance between the inner tube 26 and the flats 20 is less than the radial thickness of the fingers 8 at the projections 10 and there is a positive clamping force produced by the resulting elastic deformation of the outer member 4. The device is self-locking in this position since the clamping force has no component tending to return the outer member 4 to the disengaged position.

It will therefore be seen that the device is extremely simple to use, as a quick twist in one direction or the other will bring it to the respective end position in which the inner tube is either clamped or unclamped. The two parts of the device are held permanently in place on the outer tube once assembly has been completed, so that there is no danger of them becoming disengaged from each other, nor is the clamping operation easily disturbed by the ingress of foreign matter.

Claims

1. A clamping device for a pair of telescopically slidable elements, the device comprising inner and outer members arranged to be mounted on one of the elements and being relatively movable between opposite end positions while being retained in engagement with each other, in the movement to one of which positions co-operating means on the members are displaced to lock the elements together axially, and in the other said end position the elements are telescopically slidable to each other.

2. A clamping device according to claim 1 wherein said members are rotatable about the axis of the telescopic movement between said end positions.

3. A clamping device according to claim 2 wherein the outer member comprises a portion that is resiliently snap-fitted upon the inner member to retain the members axially together while permitting them to rotate between said end positions.

4. A clamping device according to any one of claims 1 to 3 comprising cam means for effecting said locking action.

5. A clamping device according to claim 4 wherein the inner of said members comprises at least one flexible element that is urged into engagement with the other of said telescopically slidable elements by cam means on the outer member to lock the pair of slidable elements together.

6. A clamping device according to claim 5 wherein the or each said flexible element is formed as a finger projecting axially from a tubular portion of the inner member.

7. A clamping device according to claim 5 or claim 6 wherein the outer member comprises a sleeve surrounding the inner member and carrying said cam means for displacing said at least one finger inwardly.

8. A clamping device for a pair of telescopically slidable elements, the device comprising inner and outer members arranged to be mounted on one of the elements and to be displaceable relative to each other between alternative angular positions in one of which the elements are axially locked together by the device and in the other of which the elements are telescopically slidable.

9. A clamping device for a pair of inner and outer telescopically slidable elements, the device comprising inner and outer tubular members of resilient plastics material axially secured together, the inner member having means arranged to fix it to the outer telescopic element and to engage the inner telescopic element, there being cam means on the outer member operable to apply pressure to said engagement means of the inner member to cause the inner member to clamp the inner telescopic element and thereby lock both elements together, said cam means being arranged to be brought into operation by relative rotary movement between the members, there being a movement of less than one complete revolution between the operative and inoperative states of the cam means.

10. A combination of a pair of telescopically slidable elements and clamping means according to any one of the preceding claims secured thereto for releasably locking the elements together.

11. A combination according to claim 10 wherein the inner member is located on the outer telescopic element by portions that project through apertures in the outer element and that have inner faces for engagement with the inner telescopic element.

12. A combination according to claim 11 wherein the outer member overlies said portions of the inner member to prevent their withdrawal from said apertures, thereby preventing removal of the inner member from said outer telescopic element.

13. A combination according to any one of claims 10 to 12 wherein the outer member is resiliently deformed by the engagement of the inner member with the inner telescopic element when the elements are locked together axially, whereby to apply a clamping force to the inner telescopic element.

14. A clamping device for a pair of telescopically slidable elements constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.

15. A product in which at least one pair of telescopically slidable elements is releasably clamped by a clamping device according to claim 14.