COUPLING DEVICE

The invention relates to a coupling device of the type that is defined in the preamble to claim 1.

As a rule, the coupling device is included as a component in a building system for building frames, for instance a frame which, covered with tarpaulins, forms a protective cover for an object, such as a boat, during a winter period for example.

The coupling device serves to interconnect two poles which are positioned at a distance from one another. The poles may consist of pipes with an outer diameter within a preselected diameter range.

The actual coupling device may comprise two tubular elements of which the first has an inner diameter which substantially corresponds to an outer diameter of the second tubular element and is axially movably received in the second tubular element. A clamping means may be arranged in the overlap area of the two tubular elements to lock the tubular elements against axial displacement and rotation relative to each other. Each tubular element has at its free end a hook member with a recess to receive one of said poles.

Prior art coupling devices of the type in question have heavy limitations with respect to the diameters and mutual direction of the connecting poles, and moreover the locking means for securing a pole in a hook member are complex with respect to design and handling.

An object of the invention therefore is to provide a coupling device which enables simple, reliable and stable connection to poles of different outer diameters and with varying directions.

Further objects will be evident directly or indirectly from the following description.

The object is achieved wholly or partly by means of the invention.

The invention is defined in independent claim 1. Embodiments of the invention are defined in the dependent claims .

Possible features of the inventive coupling device are that each hook member may have a shaft part which may be received in the tubular element connecting to the hook member and adjoin the inner surface of the tubular element at least at three circumferentially spaced-apart places to form a pivotal mount for the hook shaft part in the tubular element, and that the hook member may have a duct extending coaxially through the shaft part and provided with an inner thread, which threadingly may receive an outer thread of a screw which extends coaxially to the shaft and has its one end fixedly connected to the tubular element in an axially inner part thereof, the other end of the screw being capable of projecting into the hook recess, and that the hook recess is designed to allow the end part of the screw to hit a pole which is received in the recess and rests on the bottom thereof at a distance beyond the centre of the pole, seen from the bottom of the recess.

The poles may suitably have the form of pipes, which may have the same cross-sectional dimensions as the two tubular elements of the coupling device.

The clamping device may have the form of an axially slotted sleeve which at each slot edge has a radially protecting flange, the flanges being interconnected by means of a clamping screw, which allows the flanges to be moved towards each other to allow the tightening ring to be forcefully connected to the outer of the two telescopically cooperating tubular elements in their overlap area. The outer tubular element suitably has a pair of axially directed through slots in its end portion, all the way to the end, to be more easily deformed to frictional interference with interior tubular

elements. The clamping ring may have on its inside projecting protrusions which engage the slots of the tubular element and come into contact with the outer circumference of the interior tubular member when tightening the clamping ring.

A gap may be left between the projecting legs of the clamping ring, also in the tightened state of the clamping ring.

A stay which extends generally radially to the clamping device may, with a tongue, be inserted between the legs of the clamping device, the clamping screw of the clamping device extending through an opening in the tongue to secure the clamping tongue therein, optionally in such a manner that the legs of the clamping device between them clamp the tongue. The stay may have the form of a telescopic tube with a clamping device, equivalent to the coupling device, except that at least one of the hooks of the coupling device is replaced with said tongue. The opening of the tongue for the clamping screw of the clamping fitting may have the form of a slot which extends at an acute angle to the axis of the stay, towards the stay. The hook shaft part is positioned at an axial distance from the end of the hook screw which is attached to the tubular element to enable a flexurally strong attachment of the hook to the tubular element. The end of the screw may be fixedly connected to a disc, whose outer diameter substantially corresponds to the inner diameter of the tubular element. The outer circumference of the disc may have a countersink into which the tubular element can be deformed to establish the connection.

The invention will in the following be described by way of example and with reference to the accompanying drawings . Fig. 1 illustrates schematically an axial section through a coupling device according to the invention.

Fig. 2 illustrates schematically a section taken along the line II-II in Fig. 1.

Fig. 3 illustrates schematically a section taken along the line III-III in Fig. 1, supplemented with a stay that connects to a clamping device in the section. Fig. 4 illustrates schematically a sectional view taken along the line IV-IV in Fig. 3.

The coupling device according to Fig. 1 comprises a longitudinally variable pole 1 having a mutually rotatable hook member 3 at each end. The pole 1 comprises two tubular elements 2, 2', of which the tubular element 2 ' has an outer diameter corresponding to the inner diameter of the tubular element 2. The tubular element 2 has at its overlap end a pair of diametrically opposite end slots 21 in the overlap area of the tubular elements. Each hook 3, 3' has a shaft part 4, 4' which extends into the end of the tubular element and adjoins the inner surface of the tubular element around its circumference. The shaft 4 has a centrally throughgoing duct 5 with an inner thread, said duct being concentric with the tubular elements 2, 2' and receiving a screw 6, which is stably attached to the tubular element 2 by means of a disc 7 which is fixedly connected to the screw end and the inside of the tubular element respectively, preferably by means of a deformation connection. The hook shaft 4 is thus flexurally rigidly attached to the tubular element 2 by means of the screw 6 (and the attachment of the disc 7 to the tubular element 2 and the screw 6) . The hook 3 has a hook recess 31, which receives a pole 2'', which is shown to have the form of a pipe, the pole 2' ' being capable of having an outer diameter corresponding to that of the tubular element 2 or 2 ' .

In the overlap area between the tubular elements 2, 2', a clamping device 10 is shown, which is arranged to elastically deform the tubular elements 2, 2' into locking frictional engagement with each other in the overlap area.

The hook recess 31 has a mouth which is directed transversely to the axis 8 of the tubular element 2, 2' and has such a depth that the pole 2 ' ' involved has its centre 9 positioned between the axis 8 and the bottom of the hook recess 31 when the pole 2 is fully inserted in the recess 31. The end 61 of the screw 6 which extends into the hook recess 31 is shown to be smooth and convexly rounded and thus hits the pole 2 ' ' which is circular in cross-section in a position for which the pole 2' ' is firmly clamped in the hook and wedged against the bottom of the hook recess. The two hook legs are substantially parallel and the hook recess is substantially semicircular under the axis 8 in the section according to Fig. 1. It will be appreciated that the screw end 61 causes elastic deformation of the pole element 2' formed as a tubular element, so that this is also locked against axial displacement and rotation in the hook 3.

The tubular element 2 forms a comfortable grip for manual screwing of the screw 6 through the hook shaft 4, to facilitate manual fastening of the pole 2 ' ' in the hook. The same applies to the pole 2'' in the hook 3'. The two poles 2 ' ' extend in parallel planes but may extend in optional directions in the respective planes since the tubular elements 2, 2' are rotatable relative to each other when the poles 2 ' ' are fixedly clamped to the respective hooks 3, 3'. The tubular elements 2, 2 ¹ are axially movable to establish an optional length between the hooks 3, 3', and the clamping device 10 can finally be clamped in the telescopic overlap area between the tubular elements 2, 2', whereby they are locked against axial displacement and rotation relative to each other .

It is evident from Fig. 2 that the hook shaft 4 may be square with bevelled corners which adjoin the inner surface of each tubular element.

As is evident from Fig. 3, the clamping device may have the form of an axially slotted tubular element 11 which on each side of the slot has a radial flange 12 with aligned openings for a locking screw 13, which at one end has a knob 14 and at the other end engages an inner thread 15 in the flange opening 12.

The flanges 12 have an intermediate gap in the closed state of the clamping device to receive a securing tongue 20, the tightening screw 13 extending through an associated opening in the tongue 20. As can be seen in Fig. 3, the end slots 21 of the tubular element 2 are arranged in two diametrically opposite areas and the clamping sleeve 11 of the clamping device has on its inside a pair of axially extending clamping strips 22, which extend through the slots 21 and contact the outer circumference of the tubular element 2' in the clamped state of the clamping device to provide a particularly stable interconnection of the tubular elements 2, 2'. The fastening tongue 20 is arranged at one end of a stay 30, which optionally can be arranged in a longitudinally variable manner and, for example, have the structure that is evident from the coupling device according to Fig. 1, except for the hook members 3 and their attachment. Instead, a fastening tongue 20 or the like may be mounted at each end of the stay 30.

As is evident from the section in Fig. 4, the tongue 20 has an opening 28 which receives the screw 13, in which case the opening 28 may optionally have the form of a slot which opens towards the lateral edge of the tongue 20 and extends at an oblique angle to the axis of the stay 30 and towards the stay 30, so that the slot 28 extends away from the tubular elements 2, 2'. Moreover the tongue 20 is shown to have a generally circularly rounded end, whose centre of curvature is suitably positioned adjacent the axis of the screw 13.

A currently preferred embodiment of the invention comprises a coupling device comprising two tubular

elements 2, 2', of which the first 2 has an inner diameter which substantially corresponds to an outer diameter of the second tubular element 2' and is axially movably received in the second tubular element, each tubular element having at its free end a hook element 5 which can receive a pole 2 ' ' therein, a clamping device 10 being arranged to allow mutually releasable connection of the tubular elements 2, 2' in their telescopically cooperating overlap area, the hook element 3, 3' having a shaft part 4, 4' which is received in the connecting tubular element 2, 2' and adjoins the inner surface thereof at circumferentially spaced-apart places to form a pivotal mount for the shaft part 4, 4' in the tubular element 2, 2', the hook member having a through duct which is coaxial with the tubular element and has an inner thread, which threadingly receives an outer thread of a screw 6, 6' whose one end is fixedly connected to the associated tubular element 2, 2' and whose other end 61 projects into the recess 31 of the hook, and a pole 2 ¹ ', which stably rests on the bottom of the hook recess 31 and which has a circular outer diameter which is at most equal to the outer diameter of the larger tubular element, having its centre positioned between the screw axis 8 and the bottom of the hook recess 31. It will be appreciated that the above description defines a currently preferred embodiment and that a person skilled in the art can make changes and modifications thereof without departing from the scope of protection of the accompanying claims. Examples of such changes comprise the pivotal mounting of the hook member 3 relative to the adjoining tubular element, 2, 2'. This pivotal mounting can be provided, for instance, by the hook member or the shaft part 4, 4' of the hook member being provided with a sleeve which is arranged round the adjoining tubular element 2, 2 ' .

The size of the hook recess is shown to be configured to receive a pole of substantially the same diameter as the tubular elements 2, 2', but may also be adjusted to poles of other dimensions as long as the pole, when placed in the hook recess, has its centre positioned between the screw axis 8 and the bottom of the hook recess 31.

The material of the various components in the present invention has not been developed above. The choice of material may be varied with respect to the different fields of application in which the coupling device can be used. For example, different metal, plastic and composite materials may be used.

It will further be appreciated that coupling ele- ments of the above described type may be included as components in a system for building frames, but may also serve to interconnect other tubular or rod-like components .

It will also be appreciated that the above described clamping device 10 can advantageously be used to lock tubular elements against axial displacement and rotation relative to each other even if these tubular elements are not provided with the above described coupling components, such as hook members and screws.