Patent Description:
During trade fairs and exhibitions, temporary exhibition stands are used for the duration of the event, and disassembled again afterwards. In a modular solution for stand building, e.g. described in <CIT>, a set of standard frame modules is provided, the modules serving as generic building blocks. By connecting together multiple frame modules, a temporary exhibition stand according to a desired design may be constructed. A frame module typically comprises a rectangular frame with a series of holes provided on each side face of the frame. The holes allow to connect a frame module to an adjacent frame module, by means of fasteners inserted through corresponding holes, the fasteners thereby allowing for a releasable connection. Typically, the holes are relatively large, thereby avoiding that frame modules would have to be positioned very accurately before connection. After constructing the skeleton by means of multiple connected frame modules, the walls may be covered with panels or canvases to obtain the desired look of the temporary exhibition stand. Very large stands may be constructed with such a modular solution, often comprising multiple floors and using tens to hundreds of frame modules.

Typically, for releasably connecting the frame modules, no standard fasteners are used, but connectors specifically designed for use in the modular system, often allowing for a toolless application. Besides being adapted to the layout of the frames and holes, the connector needs to provide a highly reliable and robust connection of frame modules. Indeed, in the case of an impact on the construction, e.g. someone falls against the exhibition stand, the connector needs to withstand the occurring tensile and bending loads, thereby preventing that the whole construction would collapse.

In current modular solution for stand building, typically a screwing principle is used in the connector: the connector comprises a cylindrical body, provided with screw thread at one outer end and a head piece at the opposing outer end, and a separate second component similar to a nut. After inserting the cylindrical body through corresponding holes, the nut component is screwed onto the body, such that frame surfaces are clamped between the nut and the head piece of the body. An example of such a connector is found in <CIT> or https://www. com/en/products/parts/d30-connectors/toolless-connector-d30/.

A disadvantage of the currently used connector, is that the two individual connector components may be separated and get lost after disassembly. Moreover, for making the connection, the two parts must be brought together, requiring both hands for mounting the connector. This makes application of the connector cumbersome, and thus time-inefficient. Furthermore, for each connector to be placed, the nut component needs to be screwed onto the body, thereby requiring additional time. As substantial time is needed for application of each individual connector, assembly and disassembly of the construction may take long, certainly for stands having a huge amount of frame modules.

Accordingly, there is a need for a connector allowing to connect frame modules in a more convenient and time-efficient way.

In the prior art, solutions are presented aiming at an improved assembly efficiency. For example, <CIT> discloses a rapid connecting lock for connecting adjacent display modules in a LED display screen. De connector consists of two parts, namely a lock body and a groove block. The lock body comprises a fixed block, and a rod provided with a transverse pin. The groove block comprises a groove, adapted to receive the transverse pin. In connected state, two module surfaces are clamped between the groove block and the fixed block of the lock body. The connector is brought in the locked state by rotating the groove block over <NUM> degrees, such that the transverse pin of the lock body engages with the groove of the groove block. Locking is thus obtained by means of the locking pin, thereby requiring less time than when a screwing principle is used. However, still two separate parts are used in the connector, thereby adversely affecting the ease of implementation and application efficiency. Finally, the disclosed connector is used in combination with LED frames having specific holes with elongated shape. Therefore, it cannot as such be used for connecting any type of frame modules, e.g. having large round holes.

On the other hand, connectors are known specifically focussed on providing an easy and quick fastening and release, but not being suitable for applications requiring a robust connection under load and impact conditions. For example, classical ball lock pins, like presented in <CIT> or https://uk. com/vona2/detail/<NUM>/#, are used for temporarily holding together two components, e.g. for releasably fixing a work piece, or for the alignment of sheet metal during a welding process. This one-piece connector, relying on locking by means of small balls, allows for a practical and quick application, but under impact or load conditions, would easily release unintentionally. This type of connector is therefore not suitable for connecting frame modules in a temporary exhibition stand, wherein highly reliable and robust connections need to be guaranteed under all conditions, thereby preventing collapse of the huge construction.

<CIT> discloses a device for assembling the framework of a temporary exhibition stand.

<CIT> discloses a bolt for the detachable connection of two component parts.

It is an objective of the present invention to disclose a connector that resolves one or more of the above-described shortcomings of the prior art solutions. More particularly, it is an objective to present a connector suitable for use in a temporary exhibition stand, that allows to connect frame modules in a convenient and time-efficient way, while guaranteeing a highly reliable and robust connection.

According to a first aspect of the present invention, the above identified objectives are realized by a connector for releasably connecting two modules in a modular system for temporary constructions, defined by claim <NUM>, the connector comprising:.

the connector being adapted to clamp two module parts between the front and rear clamping surface in extended condition of the first set of locking elements, after being inserted through corresponding holes in the module parts in collapsed condition of the first set of locking elements.

Thus, the invention concerns a connector. The connector is suitable for releasably connecting two modules in a modular system for temporary constructions. A temporary construction may be a temporary exhibition stand, or another type of construction that is intended to be disassembled after temporary use, like podium or decor elements. A modular system refers to a solution making use of a set of generic elements or modules, serving as building blocks. A module is for example a frame module, comprising a rectangular frame composed of four hollow columns. Other examples of modules are a display module, having a LED display mounted on a frame, or a truss module, having an elongated rectangular frame provided with internal braces. The module comprises holes, allowing to connect the module to another module by means of a connecter inserted through corresponding holes of both modules. Typically, each side face of the frame is provided with a series of holes, positioned according to a spatial grid. Typically, the holes are relatively large, thereby avoiding that frame modules would have to be positioned very accurately before connection. In connected state, two module parts, comprised in two respective modules, are clamped together. For example, the module part is one of the columns of a frame module, and in connected state side faces of respective columns are clamped against each other. Other shapes of module parts are possible, as long as holes are provided that allow to connect adjacent modules by means of a connector placed through corresponding holes.

The connector comprises a sleeve, extending in longitudinal direction between a front and rear outer end. A sleeve refers to a hollow, elongated body. In an embodiment, the sleeve comprises a central portion, of which any transverse cross section is circular or has an envelope being circular. For example, the sleeve has a cylindrical central portion, in which grooves and/or slits may be provided. In an embodiment, the sleeve comprises a conical end portion connected to the central portion and located at the rear outer end of the sleeve. Such a conical end portion allows for an easy insertion of the connector into a hole of the module part.

The connector further comprises a head piece. The head piece is attached to the front outer end of the sleeve. In an embodiment, the head piece may be detachable from the sleeve, but during use of the connector, it is in attached condition. The head piece comprises a flat surface. When the head piece is attached to the sleeve, the flat surface defines a front clamping surface situated in a transverse plane and facing the sleeve. The front camping surface is a first surface that will contribute to clamping the module parts.

The sleeve comprises one or more circumferential slits at a first longitudinal position, in which a first set of one or more locking elements are placed. A slit refers to an opening having an elongated shape. The slit is circumferential, meaning that it extends across the whole or part of the circumference of the sleeve. The sleeve may comprise one slit, in which multiple locking elements are placed, may comprise multiple slits, with one locking element per slit, may comprise multiple slits with multiple locking elements in one slit, etc. In an embodiment, the first set of locking elements contains two separate locking elements, opposing each other in a transverse cross section.

Every locking element comprised in the first set is movable between a collapsed condition and an extended condition. In collapsed condition, the locking elements are completely or partly recessed in the sleeve. This may also be referred to as a retracted position of the locking elements. In the extended condition, the locking elements protrude from the sleeve, meaning that a larger portion of the locking elements is located outside the sleeve outer surface than is the case in collapsed condition. For example, the connector may comprise an internal body, that is movable within the sleeve by pushing a push button. By moving the internal body in longitudinal direction, the locking elements may switch from fully collapsed to fully extended condition.

Any of the locking elements of the first set comprises a flat surface. For example, a locking element has one flat side facing the head piece, or has two opposing flat sides. In extended condition of the locking elements, any of the flat surfaces protrudes completely or partially from the sleeve. These protruding flat surfaces together define a rear clamping surface, being a second surface that will contribute to clamping the module parts. The rear clamping surface is situated in a transverse plane and faces the front clamping surface defined by the head piece.

In collapsed condition of the locking elements, the transverse cross section of the connector is small enough to be inserted through a hole of the module part. Thus, for applying the connector, the locking elements are first brought in collapsed condition, e.g. by pushing a push button, after which the sleeve is inserted through aligned holes of two adjacent modules. While being inserted, the sleeve crosses the module parts, via the holes. After being inserted, the locking elements may be brought in extended condition, e.g. by releasing the push button. In connected condition, the two module parts are clamped between the front clamping surface, defined by the head piece, and the rear clamping surface, defined by the extended locking elements. Thus, in connected condition, the two module parts are clamped between two flat surfaces, while the sleeve extends through the holes of the module parts.

The invented connector has several advantages compared to prior art connectors. Firstly, the connector allows to connect frame modules in a convenient and time-efficient way. Indeed, the connector is provided as one piece, thereby eliminating the risk that multiple connector pieces would get separated, and allowing for a convenient application. Moreover, due to the locking principle, application of the connector can be done with one hand, thereby saving time. Finally, locking the connector only requires changing the position of the locking elements, e.g. by pushing or releasing a push button. This saves a substantial amount of time compared to existing connectors wherein a nut component needs to be screwed onto the sleeve for every connector being placed.

Secondly, while allowing for an easy and quick fastening and release, the invented connector still offers the required strength and robustness. In particular, the connector allows to clamp the modules with a high clamping force, thereby enabling a connection that offers sufficient resistance against high tensile loads. Indeed, in connected condition, the two module parts are clamped between two flat surfaces of the connector. In particular, even at the position of the locking elements, a flat clamping surface is used, being provided by the flat side of the protruding locking elements. Using such a flat clamping surface ensures that occurring stresses are evenly distributed over a relatively large surface, thereby preventing that locally high stresses would arise under tensile load. The latter is essential, as concentrated point loads arising under tensile force may cause local deformations in the frame, the latter e.g. being made from Aluminium, thereby causing the connector to be pulled through the deformed frame side and releasing the connection.

In summary, the invented connector allows for a combination of increased connection speed and substantial clamping strength. Offering such a combination is not evident, as on the one hand flat clamping surfaces are important with respect to the clamping strength, but on the other hand flat surfaces do not allow for an easy surface decrease tailored to the size of the connection holes. Moreover, even when having considered to implement the surface decrease by means of retractable elements, arriving at flat retractable elements is not evident, as no advantage can be taken of the rolling nature of classic locking balls, the latter allowing for an easy retracking mechanism.

Finally, the connector also allows for a connection offering sufficient resistance against bending load and torsion. Indeed, often the frame modules have hollow columns. In connected condition of the modules, the front plates of these columns are pushed against one another. By making the sleeve of the connector long enough, however, clamping of the connector surfaces may be done on the back plates of the respective columns, instead of clamping the front plates. In this way, the long sleeve body crosses the entire two module columns, thereby preventing twisting of the modules under a torsion load.

Optionally, any locking element of the first set comprises a curved edge facing away from the sleeve. In an embodiment, the curved edge of the locking element has a transverse cross section corresponding to an arc of a circle. For example, in collapsed condition of the locking elements, the curved edges are on a circle of which the centre corresponds to the centre point of the sleeve. In other words, the curved edges, in collapsed condition, together define a circle concentrical to a transverse cross section of the sleeve. In another embodiment, the curved edges are on a circle concentric with the sleeve, when being in extended condition. Providing locking elements with a curved edge has the advantage that in extended condition, any locking element protrudes from the cylindrical sleeve over a similar height. Thus, over the circumference of the connector, in a transverse plane, a clamping surface is obtained with even distribution of occurring stresses. Moreover, in retracked position, the locking elements follow the round shape of the sleeve, thereby allowing for easy insertion through a circular hole.

Optionally, the head piece and the front outer end of the sleeve both comprise screw thread, such that the head piece, by being screwed, is movable in longitudinal direction, thereby allowing to adapt the distance between the front and rear clamping surface. In this way, the clamping length may be adapted, thereby compensating for any clearances or intolerances between two adjacent modules.

Optionally, the connector further comprises:.

wherein any cam element of the first linear cam assembly is comprised in the internal body, and any follower of the first linear cam assembly is comprised in a locking element of the first set, thereby allowing for a translation of any locking element of the first set according to a direction perpendicular to the longitudinal direction, by moving the internal body in longitudinal direction. Thus, the connector comprises one or more linear cams, for moving the locking elements of the first set between the collapsed and extended condition. One linear cam is provided per locking element of the first set. If the first set comprises multiple locking elements, multiple linear cams are provided, together forming a linear cam assembly. Every linear cam allows to move a locking element up and down with respect to the sleeve, by moving an internal body of the sleeve backward and forward. For this purpose, every locking element comprises a follower, and the internal body, placed inside the sleeve, comprises a cam element. The cam element comprises a flat surface that is inclined with respect to a transverse plane and inclined with respect to the longitudinal direction. For example, the cam element is provided as a recess or groove in the internal body, the recess or groove having a ramp. Moving the cam element in longitudinal direction causes the follower to be moved according to a translation in a transverse plane, the translation being in a direction perpendicular to the longitudinal direction. The follower and cam element together form the linear cam. Moving the internal body in longitudinal direction, causes every locking element of the first set to be translated in a transverse plane, any of these translations being perpendicular to the longitudinal direction. Using a linear cam assembly for moving the locking elements has the advantage that the locking elements may be actively pushed inwardly or outwardly. The latter is required since, given the flat shape of the locking elements, no use can be made of the rolling nature of classic locking balls.

Optionally, the connector comprises a push button, adapted to move the internal body relative to the sleeve in longitudinal direction when pushing the button, the internal body thereby being displaced towards the rear outer end of the sleeve. This means that a portion of the internal body being inside the hollow sleeve, moves away from the front outer end of the sleeve and approaches the rear outer end of the sleeve.

Optionally, the connector comprises a spring, adapted to move the internal body relative to the sleeve in longitudinal direction when releasing the button, the internal body thereby being displaced towards the front outer end of the sleeve. This means that a portion of the internal body being inside the hollow sleeve, moves away from the rear outer end of the sleeve and approaches the front outer end of the sleeve.

Optionally, the sleeve comprises one or more openings at a second longitudinal position, located between the first longitudinal position and the front outer end, and the connector comprises a second set of one or more locking elements, wherein the one or more locking elements of the second set are placed in the one or more openings of the sleeve at the second longitudinal position, and are movable between a collapsed condition, wherein the locking elements are at least partially recessed in the sleeve, and an extended condition, wherein the locking elements protrude from the sleeve. This implies that, additional to the first set of locking elements, the connector comprises a second set of locking elements. The second set of locking elements are placed at a second longitudinal position, between the head piece and the first set of locking elements. For this purpose, the sleeve comprises one or more openings at the second longitudinal position. Various shapes are possible for the locking elements of the second set. In an embodiment, the locking elements of the second set have a shape similar like the locking elements of the first set, thus comprising a flat surface at one side or both sides. In this case, the openings at the second longitudinal position are provided as circumferential slits. In another embodiment, the locking elements of the second set have a round shape, thus being provided as balls. In this case, the openings at the second longitudinal position may be round openings.

The advantage of providing a second set of locking elements, is that rotation of the connector, when being mounted, may be avoided. Indeed, after inserting the connector through the connection holes, the locking elements of the second set are in extended condition, just like the locking elements of the first set. When rotating the connector around its axis, the locking elements of the second set may engage with blocking elements provided at the inside of the frame module, thereby impeding a further rotation of the connector. In this way, adjusting the clamp length by screwing of the head piece can be done in a convenient way, without being hindered by a spinning connector. Furthermore, a preferred angular position of the connector may be ensured. For example, the locking elements of the second set may be placed such that, when blocking a further rotation, the locking elements of the first set clamp at a preferred surface of the frame module, e.g. at that side of the hole where the frame has the highest strength.

Optionally, each of the openings at the second longitudinal position is a circumferential slit, and each of the locking elements of the second set comprises a flat surface, such that in the extended condition, the associated protruding flat surfaces together define a central clamping surface situated in a transverse plane and facing the front clamping surface. This implies that, just like the first set of locking elements, the locking elements of the second set have a flat surface. For example, they have one flat side or two opposing flat sides. The advantage of using flat locking elements in the second set, is that these locking elements may contribute to clamping the modules. Indeed, the locking elements of the second set may be positioned such that, in mounted condition of the connector, they are in contact with, or close to, an internal face of a frame module. During impact, clamping will be done at two different positions: between the head piece and first set of locking elements, and between the head piece and second set of locking elements. Just like for the first set of locking elements, the flat clamping surface provided by the second set of locking elements, allows for an even distribution of occurring stresses during impact. This further contributes to a high clamping force, thereby enabling a connection that offers sufficient resistance against high tensile loads.

In an embodiment, any locking element of the second set comprises a curved edge facing away from the sleeve, the curved edge having a transverse cross section corresponding to an arc of a circle. In a further embodiment, the second set of locking elements contains two separate locking elements, opposing each other in a transverse cross section.

Optionally, any locking element of the second set has an angular position rotated over <NUM> degrees relative to one of the locking elements of the first set. This implies that, in a front view of the connector and extended condition of all locking elements, a central point or centre point of a locking element of the second set is rotated over <NUM> degrees compared to the central or centre point of a locking element of the first set. In an embodiment, the first and second set of locking elements contain the same amount of locking elements, such that any locking element of the second set corresponds to another locking element of the first set, the angular position of the former being rotated over <NUM> degrees relative to the latter. In an embodiment, any locking element of the second set has the same shape as one of the locking elements of the first set, but has an angular position rotated over <NUM> degrees. For example, the locking elements of both sets may be positioned such that in extended condition of the locking elements, a transverse cross section at the first longitudinal position is obtained by rotating the transverse cross section at the second longitudinal position over <NUM> degrees.

Optionally, the connector further comprises a second linear cam assembly, comprising, per locking element of the second set:.

wherein any cam element of the second linear cam assembly is comprised in the internal body, and any follower of the second linear cam assembly is comprised in a locking element of the second set, thereby allowing for a translation of any locking element of the second set according to a direction perpendicular to the longitudinal direction, by moving the internal body in longitudinal direction. This implies that, similar like the first set of locking elements, a linear cam mechanism is used for moving the locking elements of the second set, between the collapsed and extended condition.

Optionally, the longitudinal position of the one or more cam elements of the first linear cam assembly, and the longitudinal position of the one or more cam elements of the second linear cam assembly, is such that moving the internal body in longitudinal direction causes the locking elements of the first and second set to be translated sequentially. This implies that the two cam assemblies are designed and positioned such that, when moving forward or backward the internal body, a locking element of the second set and a locking element of the first set do not move simultaneously, but in a consecutive, non-synchronous way. In other words, when moving the internal body in longitudinal direction, the locking element of the first set and the locking element of the second set are changed from collapsed to extended condition in a successive, sequential way. Thus, there is a delay between the elements of the first set being collapsed and the elements of the second set being collapsed: when moving the internal body towards the rear outer end of the sleeve, the locking elements of the second set collapse first, and the locking elements of the first set collapse afterwards. Similarly, when moving the internal body towards the front outer end of the sleeve, the locking elements of the first set extend first, and the locking elements of the second set extend afterwards, after some delay. In this way, it can be ensured that the first set of locking elements will always move to the extended condition, thereby guaranteeing sufficient clamping of the modules. Indeed, even if extending the locking elements of the second set is somehow blocked or hindered, this does not impede the first locking elements to be extended.

the connector being adapted to clamp a module plate between the locking elements of the third set and the locking elements of the fourth set, in extended condition of the third and fourth set of locking elements, thereby allowing to releasably attach the connector to a module.

This means that, additional to the first set of locking elements, the connector comprises a third and fourth set of locking elements. The third and fourth set of locking elements are placed at a third respectively fourth longitudinal position, between the head piece and the first set of locking elements. For this purpose, the sleeve comprises one or more openings at the third and fourth longitudinal position. Various shapes are possible for the locking elements of the third and fourth set. In an embodiment, the locking elements of the third and fourth set have a shape similar like the locking elements of the first set, thus comprising a flat surface at one side or both sides. In this case, the openings at the third respectively fourth longitudinal position are provided as circumferential slits. In another embodiment, the locking elements of the third and fourth set have a round shape, thus being provided as balls. In this case, the openings at the third respectively fourth longitudinal position may be round openings. The locking elements of the third and fourth set may be mutually connected or may be separate. The mutual distance between the third and fourth longitudinal position is such that a plate of the module fits in between. In particular, it is such that, in extended condition of the locking elements, the plate can be clamped between a locking element of the third set and a locking element of the fourth set. In this way, the connector may be releasably attached to an individual module, after disassembly of the temporary construction. Indeed, the connector may be inserted through a connection hole of the individual module, in collapsed condition of the locking elements, and when the third and fourth locking element are at both opposing sides of the module plate, the locking elements are extended. The module plate is thus clamped between the locking elements of the third and fourth set respectively. This has the advantage that, after disassembly of the temporary construction, connectors may be attached to a module during transport or storage. By holding the connectors in such a way, it is prevented that connectors would get separated from the frame modules, or would get lost.

This implies that any locking element of the third set is connected to a locking element of the fourth set, by means of an intermediate element. The combined locking element is placed in a circumferential slit extending between the third and fourth longitudinal position. In this way, when a plate module is clamped between a locking element of the third set and a locking element of the fourth set, the module plate may as well be clamped against the intermediate element. This allows the connector to be held in a firmer way, not being loose and less being subject to vibrations. Moreover, providing a wider slit results in a more robust sleeve design and improved manufacturability. Indeed, no small piece of sleeve material, being difficult to manufacture and forming a weak point, is present as would be the case when two separate small slits would be used.

In an embodiment, any locking element of the third and fourth set comprises a curved edge facing away from the sleeve, the curved edge having a transverse cross section corresponding to an arc of a circle. In a further embodiment, the third and fourth set of locking elements each contains two separate locking elements, opposing each other in a transverse cross section. In a further embodiment, the third and fourth longitudinal position are both between the first and second longitudinal position. This implies that when a connector is provided comprising a first, second, third and fourth set of locking elements, the third and fourth set are positioned between the second set and the first set.

Optionally, any locking element of the third respectively fourth set has an angular position rotated over <NUM> degrees relative to one of the locking elements of the first set. This implies that, in a front view of the connector and extended condition of all locking elements, a central point or centre point of a locking element of the third respectively fourth set is rotated over <NUM> degrees compared to the central or centre point of a locking element of the first set. In an embodiment, the first, third and fourth set of locking elements contain the same amount of locking elements, such that any locking element of the third respectively fourth set corresponds to another locking element of the first set, the angular position of the former being rotated over <NUM> degrees relative to the latter. In an embodiment, any locking element of the third respectively fourth set has the same shape as one of the locking elements of the first set, but has an angular position rotated over <NUM> degrees. In an embodiment, the connector comprises a first, second, third and fourth set of locking elements, wherein the locking elements of the second, third and fourth set have the same angular position or orientation, while a locking element of the first set has an angular position rotated over <NUM> degrees relative to a locking element of the other sets.

Optionally, the connector further comprises a third linear cam assembly, comprising, per locking element of the third set:.

wherein any cam element of the third linear cam assembly is comprised in the internal body, and any follower of the third linear cam assembly is comprised in a locking element of the third set, thereby allowing for a translation of any locking element of the third and fourth set according to a direction perpendicular to the longitudinal direction, by moving the internal body in longitudinal direction. This implies that, similar like the first set of locking elements, a linear cam mechanism is used for moving the locking elements of the third and fourth set, between the collapsed and extended condition. In this case, any locking element of the third set is connected to a corresponding locking element of the fourth set, thereby allowing for a simultaneous movement of both locking elements by means of the follower riding on the cam element.

Optionally, the longitudinal position of the one or more cam elements of the first linear cam assembly, and the longitudinal position of the one or more cam elements of the third linear cam assembly, is such that moving the internal body in longitudinal direction causes the locking elements of the first set, and the locking elements of the third and fourth set, to be translated sequentially. This implies that the two cam assemblies are designed and positioned such that, when moving forward or backward the internal body, a locking element of the third set and a locking element of the first set do not move simultaneously, but in a consecutive, non-synchronous way. This means that, similar like the delay between the second and first set of locking elements, there is a delay between the elements of the first set being collapsed and the elements of the second set being collapsed. Or in other words, after inserting the connector through the connection holes, the locking elements of the first set will extend first, followed by extending the elements of the third and fourth set. In this way, it can be ensured that the first set of locking elements will always move to the extended condition, not being hindered by the other locking elements.

In an embodiment, the connector comprises a first, second, third and fourth set of locking elements, wherein the second, third and fourth set are translated simultaneously, while the locking elements of the first set are translated successively with respect to the other sets of locking elements.

According to a second aspect of the present invention, there is provided a system for releasably connecting frame modules in a modular system for temporary constructions, the system comprising:.

This implies that the system allows to connect two frame modules, by means of the invented connector. Every frame module comprises at least one column, which may be hollow or may be solid. In connected condition, the two columns are positioned with their front faces against one another, and the connector is placed through corresponding connection holes. The first clamping surface of the connector, provided by the head piece, is in contact with the back face of the first column, and the second clamping surface of the connector, provided by the first set of locking elements, is in contact with the back face of the second column. Thus, the connector crosses the interior of both columns and clamps the columns at their back faces. This implies that the sleeve of the connector is sufficiently long; its length is specifically adapted to the dimension in longitudinal direction of two adjacent columns. By using such a long sleeve, the connector allows for a connection offering sufficient resistance against bending load and torsion. Indeed, the long sleeve body crosses the entire two module columns, thereby preventing twisting of the modules under a torsion load.

Optionally, each of the two columns are hollow. Thus, a column of a frame module comprises a front and back plate parallel to each other with a cavity therebetween, wherein the front and back plate both comprise an inner surface and an outer surface, the inner surface of the front and back plate directed towards the cavity and the outer surface of the front and back plate facing away from the cavity. In this, the outer surface of the back plate corresponds to the back face of the column and the outer surface of the front plate corresponds to the front face of the column.

Optionally, in connected condition of the frame modules, the back plate and front plate of respective columns are positioned between the head clamping surface defined by the head piece of the connector and the central clamping surface defined by the second set of locking elements. In this case, each of the two columns is hollow, and the connector comprises a first and second set of locking elements, the latter defining a central clamping surface. In connected condition, the locking elements of the second set are positioned inside the cavity of the second column, close to the inner surface of the front plate. In this way, the second set of locking elements contributes to clamping the modules. Indeed, during impact, clamping will be done at two different positions: between the head piece and first set of locking elements, and between the head piece and second set of locking elements.

Optionally, one or more blocking elements are attached to the inner surface of the front and/or back plate of any frame module, each of the blocking elements protruding from the inner surface and extending in longitudinal direction, such that in connected condition of the frame modules, rotating the connector around the longitudinal direction causes at least one of the locking elements of the second set to engage with at least one of the blocking elements, thereby blocking a further rotation of the connector. In this case, each of the two columns is hollow, and the connector comprises a first and second set of locking elements. Every frame module comprises one or more blocking elements. For example, two blocking elements are attached to the inner surface of the front plate, at opposing sides of the holes, each of the two blocking elements comprising a flat surface extending in longitudinal direction and extending in height direction. After inserting the connector through the connection holes, the locking elements of the second set are in extended condition. When rotating the connector around its axis, the locking elements of the second set will engage with the blocking elements, thereby impeding a further rotation of the connector. In this way, adjusting the clamp length by screwing of the head piece can be done in a convenient way, without being hindered by a spinning connector. Furthermore, a preferred angular position of the connector may be ensured. For example, the locking elements of the second set may be placed such that, when blocking a further rotation, the locking elements of the first set clamp at a preferred surface of the frame module, e.g. at that side of the hole where the frame has the highest strength.

wherein the tab and the longitudinal groove are adapted to form a tongue and groove connection between the stopping clip and the connector, thereby allowing for a displacement of the connector in longitudinal connection over the length of the groove, while blocking a rotation of the connector around the longitudinal direction. Thus, the central portion of the sleeve comprises a straight groove, extending in longitudinal direction, the groove having two outer ends. A stopping clip may be placed inside a connection hole, via the cavity of a hollow frame column. By inserting the tab of the clip into the groove of the connector, the connector may only be moved backward and forward over the length of the groove. Thus, the connector can be shifted to disconnect two modules, but after disassembly the connector remains attached to one of the modules. In this way, it is prevented that connectors would get lost, e.g. during disassembly of the temporary construction. Moreover, the tab and groove only allow for a translation of the connector in longitudinal direction, while blocking a rotational movement. In this way, the stopping elements constitute an alternative to the second set of locking elements, for stopping spinning of the connector and fixing its orientation in a connection hole.

Optionally, the back plate of any frame module is adapted to be clamped between the third and fourth set of locking elements, in extended condition of the third and fourth set of locking elements. In this case, each of the two columns is hollow, and the connector comprises a first, third and fourth set of locking elements. The spacing in longitudinal direction between the third and fourth set, and the thickness of the back plate of a frame module, is such that the back plate may be clamped between the third and fourth set of locking elements. In this way, when being held during transport or storage, the connector may be positioned such that it extends into the interior of the rectangular frame, and at least partly extends into the cavity of a frame column.

Optionally, the third longitudinal position and fourth longitudinal position are such that, when the sleeve is inserted in any of the holes and the back plate is clamped between the third and fourth set of locking elements, the rear outer end of the sleeve does not protrude beyond the outer surface of the front plate. Thus, the position of the third and fourth set of locking elements, and the sleeve length are such that, when the connector is held during transport or storage, the rear end of the sleeve does not protrude outside the front plate of the module column. In this way, the attached connector does not hinder the modules when being manipulated or stacked. On the other hand, it is preferred that the third and fourth set of locking elements are not too close to the rear outer end of the sleeve, thereby avoiding an excessive cantilever of the connector when being held by a frame module.

According to a third aspect of the present invention, the use of a connector is provided, the connector being according to the first aspect of the invention. The use concerns use of the connector for releasably connecting modules in a modular system for temporary constructions. In an embodiment, the use concerns use of the connector for releasably connecting frame modules in a modular system for temporary exhibition stands.

<FIG> show a connector <NUM> according to an embodiment of the invention. The connector <NUM> comprises a hollow sleeve <NUM>, extending in longitudinal direction X, between a front outer end <NUM> and a rear outer end <NUM>. An internal body <NUM> is placed inside the hollow sleeve <NUM>, wherein some portion of the internal body <NUM> protrudes from the sleeve <NUM>, at the front outer end <NUM>. The internal body <NUM> is movable relative to the sleeve <NUM>, in X direction. The connector <NUM> further comprises a head piece <NUM>, which is screwed onto the front outer end <NUM> of the sleeve <NUM>. For this purpose, screw thread <NUM> and <NUM> is provided on the head piece <NUM> and sleeve <NUM> respectively. The head piece <NUM> comprises a flat surface <NUM>, serving as a front clamping surface. <FIG> shows the sleeve <NUM> without the head piece <NUM> being attached. The sleeve comprises a cylindrical central portion <NUM>, provided with a longitudinal groove <NUM>. The central portion <NUM> is positioned between a portion <NUM> at the front outer end <NUM>, and a portion <NUM> at the rear outer end <NUM>, the portion <NUM> having a conical shape. In the shown embodiment, the length of the sleeve <NUM>, measured in X direction between outer ends <NUM> and <NUM> is <NUM>. The diameter of the central portion <NUM> of the sleeve <NUM> is <NUM>. The distance measured in X direction between the outer end of the internal body <NUM>, on the left side of the figure, and the rear outer end <NUM> of the sleeve <NUM> is variable between <NUM> and <NUM>.

The sleeve <NUM> comprises two circumferential slits <NUM>, <NUM> at a first longitudinal position. Each of the circumferential slits <NUM>, <NUM> is an elongated opening, covering part of the circumference of the sleeve <NUM>. The sleeve <NUM> comprises two circumferential slits at a second longitudinal position, of which only slit <NUM> is visible on <FIG>. The circumferential slit <NUM> is an elongated opening, covering part of the circumference of the sleeve <NUM>. The sleeve <NUM> comprises two circumferential slits at a third longitudinal position, of which only slit <NUM> is visible on <FIG>. The circumferential slit <NUM> is an elongated opening, covering part of the circumference of the sleeve <NUM>. As can be seen on the figure, slit <NUM> is broader than slits <NUM> and <NUM>.

The connector <NUM> comprises a first set of locking elements <NUM>, positioned at a first longitudinal position, close to the rear outer end <NUM>. The first set of locking elements <NUM> consists of two separate locking elements <NUM> and <NUM>, opposing each other in a transverse cross section. The locking element <NUM> is placed in the circumferential slit <NUM>, and the locking element <NUM> is placed in the circumferential slit <NUM>. The locking element <NUM> comprises a flat surface <NUM> situated in a transverse plane. A transverse plane is a plane perpendicular to the longitudinal direction X. The flat surface <NUM> faces the head piece <NUM>. As can be seen on <FIG>, the locking element <NUM> comprises a second opposing flat surface <NUM>, parallel to the flat surface <NUM>. The locking element <NUM> thus has two flat sides <NUM> and <NUM>. Furthermore, the locking element <NUM> comprises a curved edge <NUM>. The other locking element <NUM> of the first set <NUM> has an identical shape as the locking element <NUM>.

The connector <NUM> further comprises a second set of locking elements <NUM>, positioned at a second longitudinal position, between the head piece <NUM> and the first set of locking elements <NUM>. The second set of locking elements <NUM> consists of two separate locking elements <NUM> and <NUM>, opposing each other in a transverse cross section. The locking element <NUM> is placed in the circumferential slit <NUM>. Similarly, the locking element <NUM> is placed in a circumferential slit, the latter not visible on the figure. The locking elements <NUM> and <NUM> have a shape similar like the locking element <NUM>. In particular, the locking elements <NUM> and <NUM> both have two opposing flat sides and a curved edge. With respect to locking element <NUM>, the flat surface <NUM> situated in a transverse plane and facing the head piece <NUM> is indicated in <FIG>. The locking element <NUM> of the second set <NUM> has an angular position rotated over <NUM> degrees relative to the locking element <NUM> of the first set <NUM>. The locking element <NUM> of the second set <NUM> has an angular position rotated over <NUM> degrees relative to the locking element <NUM> of the first set <NUM>.

The connector <NUM> further comprises a third set of locking elements <NUM>, positioned at a third longitudinal position, and a fourth set of locking elements <NUM>, positioned at a fourth longitudinal position. The third and fourth longitudinal position are located between the first and second longitudinal position. The third set of locking elements <NUM> consists of two separate locking elements <NUM> and <NUM>, opposing each other in a transverse cross section. The fourth set of locking elements <NUM> consists of two separate locking elements <NUM> and <NUM>, opposing each other in a transverse cross section. The locking elements <NUM> and <NUM> are connected via an intermediate element <NUM>, as is visible from <FIG>. Both the locking elements <NUM> and <NUM>, and the intermediate element <NUM> have a curved edge. The locking element <NUM> comprises a flat surface <NUM> facing the other locking element <NUM>. The locking element <NUM> comprises a flat surface <NUM> facing the other locking element <NUM>. Moreover, both locking elements <NUM> and <NUM> have two flat sides perpendicular to the longitudinal direction. The locking elements <NUM> and <NUM> together form a single element <NUM>, placed in the wider circumferential slit <NUM>. The design of locking elements <NUM> and <NUM> is identical to the locking elements <NUM> and <NUM>. The element <NUM> has an angular position rotated over <NUM> degrees relative to the locking element <NUM> of the first set <NUM>. The element <NUM>-<NUM> of the third/fourth set <NUM>-<NUM> has an angular position rotated over <NUM> degrees relative to the locking element <NUM> of the first set <NUM>. In the shown embodiment, the element <NUM> has the same angular position as the locking element <NUM> of the second set, and the element <NUM>-<NUM> has the same angular position as the locking element <NUM> or the second set. In other words, the third, fourth and second set of locking elements all have the same orientation with respect to the sleeve <NUM>, while the first set has an orientation rotated over <NUM> degrees.

<FIG> further shows that the connector <NUM> comprises a push button <NUM>. In <FIG>, the button <NUM> is pushed and all the locking elements <NUM>-<NUM> are in the collapsed or retracked condition. In collapsed condition, the locking elements <NUM>-<NUM> are recessed in the sleeve <NUM>, thus not protruding outside the sleeve's outer surface, as is also clear from <FIG>, <FIG> and <FIG>. In this condition, the connector may be inserted through connection holes of adjacent modules, as will be further explained underneath. In <FIG>, the button <NUM> is released, and all the locking elements <NUM>-<NUM> are in the extended condition. In extended condition, the locking elements <NUM>-<NUM> protrude outside the sleeve's outer surface, as is also clear from <FIG>, <FIG> and <FIG>. In this condition, the module columns are clamped between the flat surface <NUM> of the head piece <NUM> and the protruding flat surfaces <NUM> of the first set of locking elements <NUM>, as will be further explained underneath.

<FIG> illustrates the internal mechanism of the connector <NUM>, for moving the locking elements <NUM>-<NUM> between the extended and collapsed condition and vice versa. The connector <NUM> comprises an internal body <NUM>, movable in longitudinal direction X by means of the push button <NUM>. The connector <NUM> further comprises a spring <NUM>, placed inside the sleeve <NUM>, at its rear outer end <NUM>. When the internal body <NUM> is moved to the right in the figure, by pushing the button <NUM>, the spring <NUM> is compressed. Moving the internal body <NUM> to the right in the figure, implies that the portion of the internal body <NUM> that is inside the hollow sleeve <NUM>, moves towards the rear outer end <NUM> of the sleeve <NUM>. When releasing the push button <NUM>, the internal body <NUM> is displaced towards the left in the figure, due to the spring force generated by the compressed spring <NUM>. Moving the internal body <NUM> to the left in the figure, implies that the portion of the internal body <NUM> that is inside the hollow sleeve <NUM>, moves towards the front outer end <NUM> of the sleeve <NUM>.

The connector <NUM> comprises a first linear cam assembly <NUM>, second linear cam assembly <NUM>, and third linear cam assembly <NUM>, for moving the locking elements of the first <NUM>, second <NUM> and third-fourth set <NUM>-<NUM> respectively. As shown in <FIG> and <FIG>, the first linear cam assembly <NUM> comprises a cam element <NUM> and follower <NUM>, composing a linear cam for moving locking element <NUM>, and a cam element <NUM> and follower <NUM>, composing a linear cam for moving locking element <NUM>. The cam element <NUM> is provided as a recess or groove in the internal body <NUM>, having a ramp or inclined surface <NUM> ending at a flat tail. The ramp <NUM> is inclined with respect to the longitudinal direction X and with respect to a transverse plane. The follower <NUM> is in contact with the cam element <NUM> and is adapted to ride on the ramp surface <NUM>. In particular, the follower <NUM> comprises two pins <NUM>, visible on <FIG>, adapted to guide the follower <NUM> in the groove <NUM>. The follower <NUM> makes part of the locking element <NUM>, thus being adapted to move the locking element <NUM> upwards and downwards relative to the sleeve <NUM>.

This changing position of the locking elements <NUM>, <NUM> is illustrated in <FIG> and <FIG>. In <FIG>, the push button <NUM> is released, see <NUM>, and the locking elements <NUM>, <NUM> are in extended condition. The spring <NUM> is in a partly compressed condition, see <NUM>. In <FIG>, the push button <NUM> is pressed, see <NUM>, and the locking elements <NUM>, <NUM> are in collapsed condition. The spring <NUM> is in a fully compressed condition, see <NUM>. Changing the position of the internal body <NUM> from <FIG>, causes the cam elements <NUM>, <NUM> to move towards the right on the figure. Accordingly, by riding on the ramp <NUM>, <NUM>, the followers <NUM>, <NUM>, are translated in a transverse plane, these translations each being perpendicular to the longitudinal direction X, and the locking elements <NUM>, <NUM> are recessed in the sleeve <NUM>. Similarly, when changing the position of the internal body <NUM> from <FIG>, under the spring force, the followers <NUM>, <NUM> move upwards with respect to the sleeve <NUM>, thereby bringing the locking elements <NUM>, <NUM> in extended condition.

<FIG> gives a front view corresponding to <FIG>, in extended condition of the locking elements <NUM>, <NUM>. <FIG> gives a front view corresponding to <FIG>, in collapsed condition of the locking elements <NUM>, <NUM>. <FIG> show that the curved edge <NUM> of the locking element <NUM> correspond to a circular arc. <FIG> shows that, in collapsed condition, the curved edge <NUM> lies on a circle <NUM> which is concentric with the circular cross section of the sleeve <NUM>. <FIG> further shows that the circular arc of edge <NUM> corresponds to about a quarter of a full circle, thereby providing a sufficiently large clamping surface of a locking element, while allowing the locking element to be retracked inside the sleeve. Similarly, the other locking elements of the first, second, third and fourth set also have a circular edge corresponding to about a quarter of a full circle.

The second linear cam assembly <NUM> and third linear cam assembly <NUM> operate in a similar way as the first linear cam assembly <NUM>. As shown in <FIG> and <FIG>, the second linear cam assembly <NUM> comprises a cam element <NUM> and follower <NUM>. The cam element <NUM> is provided as a recess or groove in the internal body <NUM>, having a ramp or inclined surface <NUM>. The ramp <NUM> is inclined with respect to the longitudinal direction X and with respect to a transverse plane. The follower <NUM> makes part of locking element <NUM>. Similar to locking element <NUM>, locking element <NUM> comprises pins <NUM> adapted to guide the follower <NUM> in the groove <NUM>.

Furthermore, the third linear cam assembly <NUM> comprises a cam element <NUM> and follower <NUM>. The cam element <NUM> is provided as a recess or groove in the internal body <NUM>, having a ramp or inclined surface <NUM>. The ramp <NUM> is inclined with respect to the longitudinal direction X and with respect to a transverse plane. The follower <NUM> makes part of locking element <NUM>. <FIG> shows that locking element <NUM> comprises pins <NUM> adapted to guide the follower <NUM> in the groove <NUM>.

In <FIG>, the push button <NUM> is released, see <NUM>, and the locking elements <NUM>, <NUM> are in extended condition. The spring <NUM> is in uncompressed condition, see <NUM>. In <FIG>, the push button <NUM> is pressed, see <NUM>, and the locking elements <NUM>, <NUM> are in collapsed condition. The spring <NUM> is in a partly compressed condition, see <NUM>. Changing the position of the internal body <NUM> from <FIG>, causes the locking elements <NUM>, <NUM> to be translated in a transverse plane, according to a direction perpendicular to the X direction, thereby being recessed in the sleeve <NUM>. Similarly, when changing the position of the internal body <NUM> from <FIG>, under the spring force, the locking elements <NUM>, <NUM> are brought in extended condition.

In the state of <FIG>, the spring <NUM> is fully uncompressed, not exerting any resilient force. All locking elements are then in the extended condition. When pushing the button <NUM>, the state changes from <FIG>, and next to <FIG> and <FIG>, thereby gradually compressing the spring <NUM>. As first the state of <FIG> is reached, the locking elements of the second set <NUM>, third set <NUM> and fourth set <NUM> are recessed first. Only after some delay, when the state of <FIG> is reached, also the locking elements of the first set <NUM> are recessed. Thus, the linear cam assemblies are positioned and designed in such a way that pushing the button <NUM> results in a sequential translation of the locking elements, wherein the first set <NUM> is recessed last. Similarly, when releasing the pushing button <NUM>, the first set of locking elements <NUM> is extended first, followed by extending the other locking elements after some delay. In this way, it is ensured that the locking elements of the first set <NUM> will always arrive at their extended position, even if one of the other elements would be hindered from extending.

<FIG> gives an example of a frame module <NUM>, extending in longitudinal direction X, transverse direction Y and height direction Z. The frame module <NUM> has a rectangular frame, composed of four mutually connected columns, delimiting a central opening <NUM>. One such column is indicated in the figure as <NUM>. The face of the column <NUM> parallel to the YZ plane and facing the central opening <NUM> is referred to as the back face <NUM> of the column <NUM>. The face of the column <NUM> parallel to the YZ plane and opposing the back face <NUM>, is referred to as the front face <NUM> of the column <NUM>. Connection holes <NUM> extend in longitudinal direction between the back face <NUM> and front face <NUM>.

<FIG> gives a front view of two frame modules <NUM>, <NUM>, each of them having a square frame and central opening <NUM>, <NUM>. The frame module <NUM> comprises a hollow column <NUM>, and the frame module <NUM> comprises a hollow column <NUM>. Centrally on <FIG>, an intersection of both columns <NUM>, <NUM> is shown. <FIG> gives a 3D view of these frame modules <NUM>, <NUM>, in connected condition.

The hollow column <NUM> comprises a back plate <NUM>, being the plate next to the central opening <NUM>. The back plate <NUM> has an outer surface <NUM> facing the central opening <NUM>, and an inner surface <NUM> facing the internal cavity of the column <NUM>. The outer surface <NUM> of the back plate <NUM> corresponds to the back face of the column <NUM>. Moreover, the hollow column <NUM> comprises a front plate <NUM>, being the plate at the outer limit of the frame module. The front plate <NUM> has an outer surface <NUM> facing the exterior, and an inner surface <NUM> facing the internal cavity of the column <NUM>. The outer surface <NUM> of the front plate <NUM> corresponds to the front face of column <NUM>. Both the back plate <NUM> and front plate <NUM> comprises a series of holes <NUM>, wherein a hole of the back plate is aligned to a hole of the front plate.

Similarly, the hollow column <NUM> comprises a back plate <NUM>, being the plate next to the central opening <NUM>. The back plate <NUM> has an outer surface <NUM> facing the central opening <NUM>, and an inner surface <NUM> facing the internal cavity of the column <NUM>. Moreover, the hollow column <NUM> comprises a front plate <NUM>, being the plate at the outer limit of the frame module. The front plate <NUM> has an outer surface <NUM> facing the exterior, and an inner surface <NUM> facing the internal cavity of the column <NUM>.

shows the connector <NUM> in mounted condition, wherein the sleeve <NUM> extends through the holes <NUM>. In the shown embodiment, the holes <NUM> have a diameter of <NUM>. Before being inserted into the holes <NUM>, the push button <NUM> is pressed, thereby collapsing all the locking elements, such that the connector can be inserted through the holes <NUM>. Next, the push button <NUM> is released, thereby bringing the locking elements in the extended condition.

<FIG> and <FIG> show that in connected condition, the front plates <NUM> and <NUM> of both modules are pushed together: the outer surface <NUM> of front plate <NUM> is in contact with the outer surface <NUM> of the front plate <NUM>. Moreover, the figures show that the connector <NUM> clamps at the back plates <NUM>, <NUM> of both columns <NUM>, <NUM>. In this, the flat surface <NUM> of the head piece <NUM> serves as a first clamping surface, being in contact with the outer surface <NUM> of the back plate <NUM>. The flat surfaces <NUM>, provided by the first set of locking elements <NUM>, serve as a second clamping surface, being in contact with the outer surface <NUM> of the back plate <NUM>. In this way, the module columns <NUM>, <NUM> are clamped between flat clamping surfaces <NUM>, <NUM>, thereby providing for an even distribution of stresses in the back plates, and offering an increased resistance against tensile loads. Moreover, due to the substantial length of the connector <NUM>, it crosses both columns <NUM> and <NUM>, thereby providing an increased resistance against torsion loads.

After placing the connector <NUM>, its clamping length may be adjusted, by turning the head piece <NUM>. Indeed, due to the screw thread <NUM> and <NUM>, the head piece may be moved in longitudinal direction, thereby displacing the clamping surface <NUM>. In this way any clearances or tolerances may be compensated for. In the shown embodiment, the width of a column <NUM>, measured in X direction, between the outer surface <NUM> of the back plate <NUM> and the outer surface <NUM> of the front plate <NUM> is <NUM>,<NUM>. The clamping length, measured in X direction, between the flat surfaces <NUM> and <NUM> is thus in the order of <NUM>, and may be slightly adapted by screwing the head piece <NUM>.

<FIG> and <FIG> further show that, in connected condition, the locking elements <NUM>, <NUM> of the second set <NUM>, are positioned close to the inner surface <NUM> of the front plate <NUM> of column <NUM>. Thus, the back plate <NUM> of the column <NUM> and the front plate <NUM> of the other column <NUM> are positioned between the head clamping surface <NUM> defined by the head piece <NUM> and the central clamping surface <NUM> defined by the second set of locking elements <NUM>. In the shown embodiment, the locking elements <NUM>, <NUM> are not in direct contact with the front plate <NUM>, but are positioned at about <NUM>,<NUM> from the front plate. Thus, under normal conditions, clamping of the modules merely relies on the first set of locking elements <NUM>, while the second set <NUM> does not contribute to clamping the columns <NUM>, <NUM>. However, as soon as some impact happens, the locking elements <NUM>, <NUM> will come into contact with the front plate <NUM>, thereby contributing to clamping and impeding release of the connector <NUM>. Therefore, it is advantageous that also the locking elements of the second set <NUM> have a flat surface <NUM>.

<FIG> and <FIG> show that every module column <NUM>, <NUM> comprises blocking elements <NUM>, <NUM>. Indeed, a straight edge <NUM> is attached to the inner surface <NUM> of the front plate <NUM> and protrudes from this inner surface <NUM>. The straight edge <NUM> extends in height direction, and is parallel to the longitudinal direction X and parallel to the height direction Z. Another straight edge <NUM>, being parallel to the transverse direction Y and to the height direction Z, is attached to edge <NUM>. Both edges <NUM> and <NUM> together form a step inside the cavity of column <NUM>. The step exists due to a groove <NUM> extending in height direction Z, at the outside of the column <NUM>. Similarly, an internal step is formed at the opposing side, by means of the edges <NUM> and <NUM>. <FIG> shows that when the connector <NUM> is rotated around its axis, the locking elements <NUM>, <NUM> of the second set <NUM> bump into the edges <NUM> and <NUM>, thereby blocking a further rotation of the connector <NUM>.

Thus, while rotation of the connector <NUM> is blocked by means of the blocking elements <NUM>, <NUM>, the head piece <NUM> can easily be turned for adjusting the clamping length. Moreover, in this way, the second set of locking elements <NUM> together with the blocking elements <NUM>, <NUM>, determine a preferred orientation of the connector <NUM> in the hole <NUM>. Indeed, <FIG> shows that due to the blocking, clamping by the locking elements of the first set <NUM> happens at the part <NUM> of the back plate close to the corner of the column, not at the part <NUM> intermediate between two connection holes <NUM>. This is due to the fact that the locking elements of the first set <NUM> are rotated over <NUM> degrees compared to the locking elements of the second set <NUM>. Clamping at the portions <NUM> is advantageous, because the portions <NUM> close to the column corners have an increased strength compared to the intermediate portions <NUM>.

Finally remark that because of the presence of the blocking elements <NUM>, <NUM>, it may happen that the locking elements of the second set <NUM> do not extend immediately after releasing the push button <NUM>. For this reason, the above explained delay is implemented with respect to the linear cam assemblies, ensuring that the first set of locking elements <NUM> always extend first.

<FIG> illustrates how the connector <NUM> can be held by an individual frame module <NUM>, by means of the locking elements of the third and fourth set <NUM>, <NUM>. In this state, the modules with attached connector <NUM> may be stored or transported, after disassembly of the temporary construction. <FIG> shows that the back plate <NUM> of column <NUM> is clamped between the locking elements <NUM>, <NUM> and <NUM>, <NUM>, the locking elements being in extended condition. In particular, the back plate <NUM> is clamped between the flat surfaces <NUM> and <NUM> of the locking elements <NUM>. Moreover, when being clamped, the inner circumference of the hole <NUM> is clamped against the intermediate element <NUM>, thereby ensuring increased stability of the connector <NUM> during transport.

<FIG> further sows that in the transport or storage state, the front end of the connector <NUM>, with attached head piece <NUM>, extends into the central opening <NUM> of the module <NUM>. Moreover, the rear end of the connector, having the conical end, is positioned inside the internal cavity of the column <NUM>. Thus, it does not protrude beyond the outer surface <NUM> of the front plate <NUM>. In particular, the third and fourth set of locking elements <NUM>, <NUM> are positioned in such a way that, on the one hand, the rear outer end of the connector does not protrude beyond the front plate <NUM>, and, on the other hand, the connector length positioned inside the central opening <NUM> is relatively limited. In this way, the attached connector <NUM> does not hinder manipulation or stacking of the modules, while at the same time excessive cantilever of the connector during transport or storage is avoided.

<FIG> illustrate how stopping clips <NUM>, <NUM> may be used in combination with the connector <NUM>. <FIG> gives a 3D view of a stopping clip <NUM>. The stopping clip <NUM> comprises a surface <NUM>, with on both sides a tab <NUM> and <NUM> respectively. <FIG> shows that the sleeve <NUM> comprises two longitudinal grooves <NUM> and <NUM> at its outer surface. Two additional grooves are provided at the other side of the sleeve <NUM>, not being visible on <FIG>. The grooves <NUM> and the tabs <NUM> are such that a tab <NUM> can be inserted into a groove <NUM>. In this way, a tongue and groove connection is formed between the stopping clip <NUM> and the sleeve <NUM>, wherein the connector may be displaced in longitudinal direction X, but a rotation of the connector is blocked. The connector <NUM> may be displaced in longitudinal direction over the length of groove <NUM>, between the outer ends <NUM>, <NUM> of the groove <NUM>.

<FIG> shows that the two stopping clips <NUM>, <NUM> may be placed inside the cavity of a column <NUM>, via a connection hole <NUM>. Via the tabs <NUM>, <NUM> engaging with the grooves <NUM>, <NUM>, the connector <NUM> is attached to the frame module <NUM>; the connector may only be shifted in longitudinal direction over the length of the grooves <NUM>, <NUM>, and cannot be detached from the module. In <FIG>, the connector is in the transport or storage state, as is the case in <FIG>, wherein the front plate <NUM> is clamped by the locking elements of the third and fourth set <NUM>, <NUM>. Thus, after disassembly, the connector <NUM> remains attached to the frame module <NUM>, thereby preventing that connectors would get lost after disassembly. On the other hand, while being positioned between the stopping clips <NUM>, <NUM>, the connector may be shifted in longitudinal direction when the locking clips are collapsed, thereby allowing to connect the module <NUM> to another module <NUM>. In connected condition of modules <NUM>, <NUM>, the stopping clips <NUM>, <NUM> prevent that the connector <NUM> is rotated around its axis. In this way, the stopping clips ensure a preferred orientation of the connector in the hole <NUM>. Therefore, the use of stopping clips <NUM>, <NUM> may be an alternative to the second set of locking elements <NUM> in combination with blocking elements <NUM>, <NUM>, as was explained with respect to <FIG>.

Claim 1:
Connector (<NUM>) for releasably connecting two modules (<NUM>, <NUM>) in a modular system for temporary constructions, wherein the connector (<NUM>) comprises:
- a sleeve (<NUM>) extending in longitudinal direction between a front (<NUM>) and rear outer end (<NUM>), the sleeve (<NUM>) comprising one or more circumferential slits (<NUM>, <NUM>) at a first longitudinal position;
- a head piece (<NUM>) adapted to be attached to the front outer end (<NUM>) of the sleeve (<NUM>), the head piece (<NUM>) comprising a flat surface (<NUM>), in attached condition defining a front clamping surface situated in a transverse plane and facing the sleeve (<NUM>);
- a first set of one or more locking elements (<NUM>), of which each locking element (<NUM>, <NUM>) comprises a flat surface (<NUM>), wherein the one or more locking elements of the first set (<NUM>) are placed in the one or more circumferential slits (<NUM>, <NUM>) at the first longitudinal position and are movable between
∘ a collapsed condition, wherein the locking elements (<NUM>, <NUM>) are at least partially recessed in the sleeve (<NUM>), and
∘ an extended condition, wherein the locking elements (<NUM>, <NUM>) protrude from the sleeve (<NUM>), such that the associated protruding flat surfaces together define a rear clamping surface situated in a transverse plane and facing the front clamping surface,
the connector (<NUM>) being adapted to clamp two module parts (<NUM>, <NUM>) between the front and rear clamping surface in extended condition of the first set of locking elements (<NUM>), after being inserted through corresponding holes (<NUM>) in the module parts (<NUM>, <NUM>) in collapsed condition of the first set of locking elements (<NUM>).