WO2011162670A2

WO2011162670A2 - Truss structure and a connection arrangement for such a structure

Info

Publication number: WO2011162670A2
Application number: PCT/SE2011/050683
Authority: WO
Inventors: Johan Schagerlind; Göran ERIKSSON
Original assignee: Sapa Profiler Ab
Priority date: 2010-06-23
Filing date: 2011-06-01
Publication date: 2011-12-29
Also published as: WO2011162670A3

Abstract

The present invention relates to a truss structure (1), comprising a plurality of elongated framing members (3, 5), such as struts and chords; a plurality of node elements (7) for connecting the framing members (3, 5) so as to form the truss structure (1), wherein each node element (7) comprises: a first holding means (11) for holding a framing member (3) extending in the longitudinal direction of the truss structure (1), and at least one second holding means (13) for holding an end piece of at least one framing member (5) extending transversely to the longitudinal direction. The second holding means (13) comprises a wedge element (35) for locking the end piece (21) at the node element (7). The present invention also relates to a solar panel arrangement comprising such a truss structure for supporting a solar panel.

Description

Truss structure and a connection arrangement for such a structure FIELD OF THE INVENTION

The present invention relates to a truss structure according to the preamble of claim 1 . The present invention also relates to a connection arrangement according to the preamble of claim 10.

BACKGROUND OF THE INVENTION

Framework constructions or truss structures are widely employed in load carrying structures due to its great load carrying capacity in relation to its weight. The truss structure is composed of framing members which are interconnected in connection points (referred to herein as node elements) in such a way that the whole truss structure behave as one structural unit. EP 1 903 1 55 B l describes a truss structure for a solar panel. The node elements disclosed in said publication are formed by extruded metal and comprise a first holding means for holding and securing framing members extending in the longitudinal direction of the truss structure, and a second holding means for holding and securing framing members extending transversely to the longitudinal direction of the truss structure. The framing members are joined to the second holding means by means of pins.

However, the use of such joints requires that the extruded nodes are provided with prebored holes after the extrusion process. Such preboring is in itself time consum- ing but also put great demands on tolerance accuracy since a plurality of framing members are to be put together in a complex lattice with a predetermined angular relationship. Moreover, the mounting of the framing members becomes complicated since the framing members are to be held in an erected position while the pins are inserted. PROBLEM TO BE SOLVED BY THE INVENTION

A problem to be solved by the present invention is thus to provide a truss structure which is easy and fast to assemble. SUMMARY OF THE INVENTION

These problems are solved by means of a truss structure and a connection arrangement as initially defined and having the features of the characterising portion of claim 1 and 10, respectively. Since the second holding means comprises a wedge element for locking the end piece at the node element the node elements do not need to be provided with prebored holes. Consequently, time is saved and the risk for rejected node elements due to prebored holes not fulfilling tolerance requirements is eliminated. Moreover, once the wedge element has locked the end piece, the framing members becomes fixed and can not adopt other positions.

Advantageously, the second holding means comprises an elongated recess extending in the longitudinal direction, wherein the recess is defined by two jaw halves forming a gap which opens in a direction being transverse to the longitudinal direction, the end piece comprises a shaft which is provided with a head at its distal end, wherein the head is larger than the size of the gap and is fitted into the recess so that the shaft protrudes from the recess via the gap, and wherein the wedge element has been fitted into the recess in the longitudinal direction so as to act on the head and press it against the inner faces of the jaw halves. Hereby the end pieces can be se- curely fitted to the node elements.

Preferably, the inner faces of the jaw halves are slanting in a convergent manner as seen in a direction out of the gap and the head has complementary mating faces, so as to abut against each other in a mutual parallel relationship when the wedge ele- ment has been fitted into the recess and is acting on the head. Hereby an accurate positioning of the end piece within the recess can be achieved.

Suitably, the top of the head is provided with at least one ridge extending in the lon- gitudinal direction, whereby the wedge element is able to slide on the ridge when being fitted into the recess. Hereby, the friction work which has to be overcome when the wedge element is fitted in the recess is decreased.

Advantageously, a plurality of transverse framing members has been fitted, by means of their end piece heads, into the recess in a side-by-side relationship.

Hereby, a plurality of framing member end pieces can be fastened by means of the one and the same wedge element.

Preferably, each shaft has different inclinations with respect to the head and pro- trudes at different angles from the recess so as to direct the transverse framing members in different transverse directions. Hereby, a simple way of arranging differently angled framing members is achieved.

Suitably, a stop element is provided at an end of the recess to correctly position the heads in the axial direction of the recess when being fitted into the recess. Hereby, a desired positioning of the end pieces can easily be achieved.

Advantageously, the end pieces are separate parts and the transverse framing members are hollow tubes, wherein a proximal end of each shaft has been inserted and clamped in the hollow tube. Hereby, a flexible way of assembling framing members having different transverse direction within the truss structure can be achieved.

Preferably, each node element comprises a plurality of second holding means being peripherally separated, as seen in the longitudinal direction. Hereby, a flexible and simple way of creating complex node elements is achieved. The truss structure is preferably employed as a supporting structure in a solar panel arrangement. Hereby is achieved a flexible and simple way of assembling such a solar panel arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to accompanying drawings, on which:

Figs, la-c show different views of a truss structure according to the present inven- tion,

Figs. 2a-c show section views of three different embodiments of a node element according to the present invention,

Figs. 3a-c show more detailed views of the node element in fig. 2a. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figs. 1-c show three different views of a truss structure 1 for supporting a solar panel arrangement. The truss structure comprises five elongated framing members 3 extending in the longitudinal direction of the truss structure 1 , and a plurality of elongated framing members extending transversely 5 to the longitudinal direction. The elongated framing members 3, 5, such as struts and chords, are connected by means of a connection arrangement in the form of node elements 7 forming the network of the truss structure 1. To this end, three different embodiments of node elements 7 are employed. On top of the truss structure 1 eight longitudinal profiles 9 are arranged. However, these profiles 9 do not have any structural function in the truss structure 1 itself, but instead serve as attachment profiles for not shown solar panels.

Figs. 2a-c show three different embodiments of node elements 7 according to the present invention, where a middle node element depicted in fig. 2a corresponds to the encircled node element denoted A in fig. lc, a top node element in fig. 2b corre- sponds to the encircled node element denoted B in fig. lc, and a lower node element in fig. 2c corresponds to the encircled node element denoted C in fig. lc.The node elements 7 have been manufactured in an extrusion process thus forming a profile having the same cross-section in the direction of the extrusion. Such elongated pro- files are thereafter cut into sections of predetermined lengths so as to form a complete node element 7.

The node elements 7 comprise a first holding means 1 1 for holding the framing members 3 extending in the longitudinal direction of the truss structure 1 , i.e. in the direction of extrusion, and at least one second holding means 13 for holding at least one framing member 5 extending transversely to the longitudinal direction of the truss structure, i.e. transversely to the direction of extrusion. For example, the node element 7 in fig. 2a comprises four second holding means 13, the node element in fig. 2b comprises two second holding means 13, and the node element in fig. 2c comprises three second holding means 13. Each second holding means 13 is adapted to hold 1-3 elongated framing members 5, each extending in different transverse directions. This will be more fully described below.

From fig. 2a-c it is shown that the first holding means 1 1 is constituted of a circular hole 1 1 with a centre axis extending in the longitudinal direction of the truss structure 1 , i.e. in the direction of extrusion. Consequently, the longitudinal framing members 3 which are in the form of circular tubes are inserted into the holes 1 1. The inner surface of the holes is provided with an axial ridge 15 while the outer surface of the tube is provided with a corresponding mating longitudinal groove 17 and the ridge 15 will slide in the groove 17 when the tube is inserted into the hole 1 1. As a consequence rotation of the tube 3 when fitted in the first holding means 1 1 is prevented. Moreover, a self-tapping screw 19 or similar means is extending perpendicularly through the node element material into the hole 1 1 so as to prevent the tubes 3 from moving in the longitudinal direction when it has been fitted into the hole 1 1 (see fig. 3 a). The second holding means 13 of the node element 7 is described with reference to fig. 3a-c showing the middle node element depicted in fig. 2a, but the same principals apply to the top and bottom node elements depicted in fig. b-c, respectively. As mentioned above, the middle node element 7 comprises four second holding means 13 adapted to hold elongated framing members 5, such as struts and chords, extending in directions being transverse to the longitudinal direction of the truss structure 1 , i.e. transverse to the direction of extrusion of the node element 7. Fig. 3a-c shows the middle node element 7 in the longitudinal direction of the truss structure having elongated framing members 5 in the form of hollow tubes 5 attached to a corresponding second holding means 13. For this reason the framing members are provided with end pieces 21 for connecting the framing members 5 to the node elements 7. The end pieces 21 are separate parts and each end piece com- prises a shaft 23 having a substantially rectangular cross-section and a head 25 which connects to the shaft 23. The head 25 is adapted to be locked in the node element 7 while the opposite shaft end is adapted to be locked within the tube 5 of the framing member. This can be accomplished in several ways, e.g. by means of not shown self-tapping screws extending through the tube wall or by clamping the tube wall onto the shaft end.

Each second holding means 13 is provided with a recess 27 extending in the direction of extrusion of the node element 7. The recess 27 is formed by means of first and second jaw halves 29, 3 1 which together define the recess and form a gap 33 between them. The gap 33 opens in a direction being transverse to the direction of extrusion. The recess 27 can be divided into two sections both extending in parallel and in the direction of extrusion, i.e. an outer and an inner section. The first section 27 is somewhat larger than the second section, when seen in the direction of extrusion of the node element 7, and is adapted to contain the heads 25 of the end pieces 21. The second section 27 is adapted to contain a wedge element 35 in the form of a pin 35 so as to wedge the heads in the first section 27. The head 25 of the end piece 21 is inserted in the recess 27 in the direction of extrusion of the node element 7. In each recess 27 up to three framing member end pieces 21 can be fitted in a side-by- side arrangement (even though larger numbers of end pieces can be contained if the node element and the end pieces are configured differently). To achieve a correct positioning in the direction of extrusion of the node element, a first stop element 37 is arranged at one end of the recess 27 so that the head 25 will abut against the stop element 37 when it is fitted into the recess 27. When all end pieces have been fitted into the recess and arranged side-by-side, a second stop element 37 is fastened at the other end of the recess to prevent the end pieces to move in the axial direction of the recess. The stop element 37 can for example be a self-tapping screw 37 which has been screwed into the material of the node element 7 adjacent the end of the recess 27 so it partly blocks it. The head 25 is larger than the size of the gap 33 so when it has been inserted into the recess 27 it can not escape through the gap 33. Instead the shafts 23 of the end pieces 21 protrude through the gap 33 in a direction defined by the inclination of the shaft 23 in relation to the head 25. As seen in fig. 3b two end pieces with shafts connecting to the associated framing members 5 have been inserted in the recess 27. A dummy end piece 21 ' is arranged between them. This is to secure a correct positioning between the two end pieces 21 , but it is of course also conceivable to use a real end piece instead if three framing members are to be fitted in the recess 27. As also depicted in fig. 3b, the shafts 21 have different inclinations with respect to the heads 25 so that the framing members 5 can be extended in different transverse direction. It is also conceivable to use end pieces having straight shafts, i.e. protruding in the normal direction of the gap.

To secure the heads 25 of the end pieces 21 within the recess 27 the wedge element 35 which is in the form of an elongated pin 35 having a length equal to the length of the recess is also inserted (after the end pieces have been positioned in the recess) in the second section of the recess so that it will be located adjacent the top of each head 25. The pin 35 is preferably fitted into the recess 27 by means of a sledge hammer or similar means. The diameter of the pin is adapted so it will act on the head 25 and press it against the outermost inner surfaces 39 of the jaw halves 29, 31. To fa- cilitate fitting of the pin in the recess, the top of the head is provided with two ridges 41 extending in the direction of the recess. Due to the ridges 41 the friction work to be overcome when forcing the pin 35 into the recess is decreased.

The outermost inner surfaces 39 of each jaw half 29, 31 is inclined in a convergent manner as seen in a direction out of the gap 33. At the same time, the head 25 comprises inclined surfaces 26 which are mating with the inclined inner surfaces 39 of the jaw halves, i.e. having a complementary form. Due to the complementary surfaces of the head and the jaw halves, the head will adopt a position where the surfaces are abutting each other in a mutual parallel arrangement when the pin 35 is acting on the head 25 and forces it towards the inner faces of the jaw halves 29, 31. Hereby, the shafts 23 of the end pieces will protrude from the gap in a more accurate way since the inclined surfaces will cooperate so as to adjust the position of the head in a plane being perpendicular to the direction of extrusion.

Claims

1. Truss structure ( 1 ) suitable for supporting a solar panel arrangement, comprising:

- a plurality of elongated framing members (3, 5), such as struts and chords,

- a plurality of node elements (7) for connecting the framing members (3, 5) so as to form the truss structure (1), wherein each node element (7) comprises:

- a first holding means ( 1 1 ) for holding a framing member (3) extending in the longitudinal direction of the truss structure (1), and

- at least one second holding means (13) for holding an end piece (21) of at least one framing member (5) extending transversely to the longitudinal direction,

characterised in that said second holding means ( 13) comprises:

- a wedge element (35) for locking the end piece (21 ) at the node element (7).

2. Truss structure according to claim 1 , wherein:

- the second holding means (13) comprises an elongated recess (27) extending in the longitudinal direction, wherein the recess (27) is defined by two jaw halves (29, 3 1 ) forming a gap (33) which opens in a direction being transverse to the longitudinal direction,

- the end piece (21 ) comprises a shaft (23) which is provided with a head (25) at its distal end, wherein the head (25) is larger than the size of the gap (33) and is fitted into the recess (27) so that the shaft (23) protrudes from the recess (27) via the gap (33), and wherein

- the wedge element (35) has been fitted into the recess (27) in the longitudinal direction so as to act on the head (25) and press it against the inner faces (39) of the jaw halves (29, 31).

3. Truss structure according to claim 2, wherein the inner faces (39) of the jaw halves (29, 31) are slanting in a convergent manner as seen in a direction out of the gap (33) and the head (25) has complementary mating faces (26), so as to abut against each other in a mutual parallel relationship when the wedge element (35) has been fitted into the recess (27) and is acting on the head (25).

4. Truss structure according to any of claim 2-3, wherein the top of the head (25) is provided with at least one ridge (41 ) extending in the longitudinal direction, whereby the wedge element (35) is able to slide on the ridge (41) when being fitted into the recess (27).

5. Truss structure according to any of claim 2-4, wherein a plurality of transverse framing members (5) has been fitted, by means of their end piece heads (25), into the recess (27) in a side-by-side relationship.

6. Truss structure according to claim 5, wherein each shaft (23) has different inclinations with respect to the head (25) and protrudes at different angles from the recess (27) so as to direct the transverse framing members (5) in different transverse directions.

7. Truss structure according to any of claim 5-6, wherein a stop element (37) is provided at an end of the recess (27) to correctly position the heads (25) in the axial direction of the recess (27) when being fitted into the recess.

8. Truss structure according to claim 7, wherein the end pieces (21 ) are separate parts and the transverse framing members (5) are hollow tubes (5), wherein a proximal end of each shaft (23) has been inserted and clamped in the hollow tube (5).

9. Truss structure according to any of the previous claims, wherein each node element (7) comprises a plurality of second holding means ( 13) being periph- erally separated, as seen in the longitudinal direction.

10. A connection arrangement for connecting a plurality of elongated framing members (3, 5), such as struts and chords in a truss structure (1), comprising:

- an extruded node element (7) comprising:

- a first holding means (1 1 ) for holding a framing member (3) extending in the direction of extrusion of the node element (7), and

- at least one second holding means ( 13) for holding an end piece (21) of at least one framing member (5) extending transversely to the direction of extrusion,

characterised in that said second holding means (13) comprises:

- a wedge element (35) for locking the end piece (21 ) at the node element (7).

1 1. Solar panel arrangement comprising a truss structure ( 1 ) as defined in any of claims 1 - 10 for supporting a solar panel.