ARRANGEMENT FOR RELEASABLE ATTACHMENT OF A UNIT TO AN ATTACHMENT SURFACE

Abstract: Arrangement for releasable attachment of a unit (1) to an attachment surface (2). The arrangement includes a first pair of cooperative engagement organs (5, 6) and a second pair of cooperative engagement organs (7, 8). In each pair of cooperative engagement organs, one organ is fastened to the attachment surface and the other organ is attached to the unit (1). In each pair of engagement organs, one engagement organ (5-8) is constituted by a wedge organ, and at least one engagement organ (7) in one of the pairs is movably attached in relation to its cooperative engagement organ (8). At assembly and disassembly, respectively, the movable engagement organ can be removed from the cooperative engagement organ, and in engagement position, said movable engagement organ is fastened against its cooperative engagement organ by means of a tightening device (26), as a rest surface (15) at the unit is in close contact with a rest surface (14) at the attachment surface.

Description: ARRANGEMENT FOR RELEASAB E ATTACHMENT OF A UNIT TO AN ATTACHMENT SURFACE TECHNICAL FIELD: The present invention relates to an arrangement for releasable attachment of a unit to an attachment surface. The arrangement is provided with a number of pairs of engagement organs which are intended to engage with each other in order to secure the attachment. In each pair of engagement organs, one organ is intended to be fastened to the attachment surface. The other engagement organ is attached to the unit. BACKGROUND OF THE INVENTION: From the US Patent 4 454 382 there is known an arrangement for releaseble attachment by means of engagement organs. Said engagement organs include hook-like organs which are intended to engage with flanges arranged on attachment rails. With this known solution, one and the same attachment arrangement can be used for different types of attachment rails. The attachment is effected by means of mould engagement, which is secured through a pressure spring. In this connection, considerable spring force is required for attachment of more heavy units, through which an attachment with limited reliability is obtained, unless extremely substantial spring forces are applied. As for example an environment which is exposed to vibrations, there is a risk that the unit, in some disadvantegous situations, vibrates until it comes loose. SUMMARY OF THE INVENTION: The object of the present invention is to provide an arrangement which ensures a secure attachment which utilizes relatively inconsiderable external tensional forces on the engagement organs forming part of the arrangement. Furthermore, a mounting is provided which is capable of considerable stress, such as vibrations and impacts/shakings. Said object is achieved by means of an arrangement which includes pairs of engagement organs according to the present invention, which is characterized in that at least one of the engagement organs in each pair is constituted by a wedge organ and that at least one of the engagement organs in one of the pairs is movably attached in relation to the corresponding engagement organ in the other pair of engagement organs. When the unit is in mounting position, the movable engagement organ is removed from the other engagement organ in the same pair of organs. When the unit is in attachment position, the movable engagement organ is tightened against the other engagement organ by means of a tightening device, as at least one rest surface at the unit is in close contact with at least one rest surface at the attachment surface. By using wedge organs according to the invention, a required engagement is provided between the engagement organs, said engagement being obtained by means of frictional engagement and standard forces, which in conjunction with a wedge effect provide considerable engagement forces at even relatively inconsiderable tensional forces, whereupon relatively heavy units can be attached to a surface. BRIEF DESCRIPTION OF THE DRAWINGS: The invention will be further described in the following with an embodiment and with reference to the annexed drawings, in which Fig. 1 illustrates the princple of the invention, Fig. 2 is a front view of a base structure forming part of the attachment arrangement, Fig. 3 is a perspective view of the base structure, Fig. 4 is a perspective view of a unit provided with engagement organs and forming part of the attachment arrangement according to the invention, Fig. 5 is a perspective view of the attachment arrangement which shows one pair of the engagement organs, at which one of the engagement organs is movable, Fig. 6 is a side view of the attachment arrangement which schematically shows a unit which shall be attached to the base structure, Fig. 7 is a corresponding side view which shows the unit in attachment position, and Fig. 8 is a top view of the unit, at which the unit is attached by means of the attachment arrangement at the base structure. PREFERRED EMBODIMENT: Thus, Fig. 1 shows the basic principle of the attachment arrangement according to the invention, said attachment arrangement being intended for attachment of a releaseable unit, for example an electronic unit such as a base station for telecommunication, for example mobile telephone traffic. The unit 1 is intended to be attached to an attachment surface 2, which for exampel can be a wall, a pole, a horizontal balk or the like. The attachment arrangement includes at least two pairs of engagement organs 5, 6, 7, 8 which, by means of mutual engagement between the engagement organs in each pair, secure that the unit is attached to the attachment surface 2. According to the invention, at least one engagement organ in each pair of organs is constituted by a wedge organ, and an optimal attachment is achieved in those cases where both engagement organs 5, 6, 7, 8 in each pair are constituted by wedge organs, as is further shown in the explanatory sketch according to Fig. 1. Thus, the engagement organs are hereinafter termed wedge organs, of which one of the wedge organs 5, 7 in each pair of organs is fastened to the attachment surface either directly or through some form of base structure, which will be described in detail below. The other wedge organ 6, 8 in each pair is attached to the releaseable unit 1, preferrably to a backside 9. The wedge organs 5-8 diclose a respective wedge surface 10, 11, 12, 13 which is located in relation to the attachment surface 2 and angled below an acute angle. The wedge angle v is selected so that considerable frictional drag is obtained, while at the same time the force which presses the wedge organs together in pairs can remain moderate. The wedge angle v is preferably the same for all the wedge organs and is for example in the size of 25-45°, in the shown example 35°, and is preferably of such size that self-locking does not occur. Furthermore, the points of the wedge organs 5, 7, which are fastened to the attachment surface, are directed away from each other, while the points of the wedge organs 6, 8 are directed towards each other. An additional condition is that the wedge surfaces 10, 12 of the wedge organs 5, 7, which are part of the attachment surface 2 , are turned towards the attachment surface, and that the wedge surfaces 11, 13 of the wedge organs 6, 8, which are part of the unit 1, are turned towards the unit. In order to achieve a wedge effect between the wedge organs in each pair of wedge organs, rest surfaces are required for each pair of wedge organs; a first rest surface 14 which is schematically illustrated in Fig. 1 by the attachment surface 2 or is constituted by a separate surface which extends in parallel with the attachment surface, and also a rest surface 15, 16 which in attachment position is in close contact with the first rest surface and is supported by the removable unit 1. According to the invention, at least one of the wedge organs 7 in the schematically shown example is one of the wedge organs which are attached to the attachment surface 2, said wedge organ being movably attached in order to be readjustable in the direction of the arrow 17. By means of the movability of the wedge organ 7, the wedge organ is readjustable between a mounting position at which the wedge organ is removed and which is shown in Fig. 1 with an unbroken line, and an attachment position which is shown with a dotted line. The principle of the mounting of the unit 1 to the attachment surface 2 is that the wedge organ 7, which thus is in an intital position, is kept removed at a distance from the wedge organ 8 which is part of the same pair, whereupon the unit 1 and its accompanying wedge organ 8 can be lifted over the wedge organ 5 without the wedge organ 8 having to encounter the wedge organ 7. The unit 1 and its support surfaces 15, 16 are pressed towards the support surface 14, whereupon the unit is lowered so that the wedge organs 5, 6 in one of the pairs are connected with each other, i.e. so that their wedge surfaces 10, 11 will be in close contact with each other. If the attachment is such that the unit 1 is hanging vertically, then the unit is allowed to hang in such a way that the two wedge organs 5, 6 are engaged with each other. In that connection the support surface 16 in the other pair of wedge organs may rest against the support surface 14 of the attachment surface 2. Thereafter, the movable wedge organ in the other pair of wedge organs 7, 8 is moved in the direction of the wedge organ 8, until their wedge surfaces 12, 13 are in close contact with each other and are tightened against each other by means of a tightening device, which will be described in detail below. By means of the tightening, a safe frictional engagement is achieved through relatively extensive frictional forces and standard forces between the wedge surfaces 10, 11 and 12, 13, respectively, in each pair of wedge organs 5 , 6 , 7 , 8. A concrete example of an embodiment will henceforth be described, at which Fig. 2 and 3 at first show a base structure in the form of an attachment support 18, which supports the wedge organs 5, 6 which are part of the attachment surface 2. The attachment support 18 is intended to be fastened to the attachment surface 2 by means of attachment members (not shown). This is for example achieved by means of screws which are inserted through holes 19 in two profile rails 20, 21, which are included in the attachment support. As is shown in Fig. 3, the profile rails 20, 21 are designed as U-profiles having a base 22 and two upstanding flanges 23, 24. Furthermore, connection organs 25, 25' are included in the attachment bracket 18, said connection organs being in the form of cross bars and intended to connect the profile rails 20, 21 with each other and to maintain a fixed relative position of the wedge organs 5, 7, which are four in the shown example. According to the invention, a tightening device 26 is included in the attachment arrangement, said tightening device being included to tighten the movable wedge organ 7 against the wedge organs 8 in a way which will be described in detail below. Fig. 4 shows an example of the construction of the unit 1, at which here only those details which are of interest as regards the understanding of the present invention will be described. In this example, the number and the location of the wedge organs 6 and 8 are selected in order to correspond to the construction of the attachment support according to Fig. 2 and 3, i.e. so that there are four wedge organs being part of the unit. In the shown example, the position of the wedge organs 6, 8 on the unit is completely fixed, said wedge organs furthermore being directed in such a way that their points 27, 28 are directed towards each other. The support surfaces 15, 16, which are described above and which cooperate with the wedge organs, are in the shown example formed of edge sections of flanges 29, 30 pointing backwards, which primarily are used as cooling flanges intended for cooling of electronics in the unit 2. The flanges are also used as organs for lateral guiding, which will be described in detail below. The tightening device 26 is in the shown example, which is best illustrated in Fig. 5, constituted by a screw 32 which is screwed in a threaded, continous drilling 31 in the wedge organ 7, said screw extending through a drilling 34 in a fixed bracket 35. The screw is rotatable in the drilling 34 without axial displacement and is accessible below the bracket 35 by means of a tool, such as a screwdriver which rotates the screw by rotating a screw head which is accessible below the bracket. A pressure spring 37 is clamped between the wedge organ 7 and the bracket 35, said pressure spring applying a force against the wedge organ which strives to hold the wedge organ in a position which is determined by the screw position in the threaded drilling 31. The movability of the wedge organ 7 is achieved by the wedge organ being fastened in the base 22 of the profile rail 21 through a guide 38, which extends in a portion of the longitudinal direction of the profile rail and cooperates with a stretcher (not shown) at the backside of the wedge organ 7, said stretcher for example being in the form of a T-profile with guide surfaces and conventionally fastening the wedge organ 7 in the profile rail 21, while at the same time allowing for a movability in the longitudinal direction of the rail. Fig. 5 also shows one of the wedge organs 8 which are part of the removable unit 2, whereupon in mounting position the wedge surface 12 of the movable wedge organ 7 is intended to be pressed against the wedge surface 13 of the wedge organ 8. Fig. 6 illustrates the mounting position for the unit 1, said mounting position constituting the initial phase in a mounting situation at which the unit 2 shall be mounted to the attachment support 18, which is described in the example above. From this it is apparent that the movable wedge organ 7 is removed in such an extent that it doesn't constitute an obstacle for the unit to be hung at the attachment support 18. By means of a unit displacement which is essentially parallel, the unit may be attached to the attachment support in such a way that the upper wedge organ 6 of the unit can be raised above the wedge organ 5 being part of the same pair, while the lower wedge organ 8 of the unit can be lowered below the wedge organ 7 being part of the same pair. Fig. 7 shows an attachment position in which the upper wedge organs 5 , 6 in the upper pair have been connected to each other by means of a wedge effect. This connection is achieved by the assistance of the cooling flanges 29 of the unit 2, the support surface 15 of said cooling flanges being in close contact with the support surface 14 of the attachment surface 2, which in the shown example form the base 22 of the profile rails 20, 21 (also, see Fig. 8). By means of the tightening device 26, the movable wedge organ 7 has been pulled downwardly, and by means of a wedge effect, said movable wedge organ has been tightened against the wedge organ 8. Since the wedge organs 6, 8 included in the unit 1 are fixedly mounted in an essentially rigid unit, the tensional force in the lower wedge pairs is transferred to a tensional force in the upper wedge pairs. Inversely, disassembly is effected by the screw 32 being screwed in opposite direction by means of the tool, whereupon the movable wedge organ 7 is raised through the assistance of the spring 37 until the position according to Fig. 6 is achieved, said position in this connection being a disassembly position. Moreover, Fig. 8 shows that organs intended for lateral guiding are provided, which means that a limited adjustment of the unit 1 is obtained and that it is impossible for the wedge organs 5-8, when mounted, to be laterally displaced from the engagement position. In the shown example, the cooling flanges 29, 30 are used for this purpose as well. For this reason, said cooling flanges cooperate with the flanges 23, 24 in the profile rails 20, 21 and protrude on both sides of said flanges, said protruding having suitable clearance. As an alternative, or as a complement, the lateral guiding is secured, as is shown in Fig. 8, by means of the cooling flanges 39, 40 cooperating with the lateral surfaces of the wedge organs. To sum it up, the unit is thus attached to an attachment surface through a number of key joints and by means of the attachment forces solely being absorbed through the active surfaces, i.e. the wedge surfaces and the support surfaces. Thus, the points of the wedge organs must not "touch bottom" against any additional support surface. An extremely stable attachment of units is provided by means of the attachment arrangement, said attachment having freedom from play and a capacity for considerable mechanical strains. Assembly and disassembly of even heavy units will to a great extent be facilitated, which is due to the fact that the unit at vertical mounting is allowed to hang in the upper wedge organs in a highly secure way, while the lower wedge organs are tightened in pairs. The invention is not limited to the embodiments which are described above and shown in the drawings, but may be varied within the scope of the appended claims. As an alternative, the wedge organs may be arranged in such a way that the support surfaces, which are described above and are part of the unit, are formed by surfaces on the wedge organs. The number of pairs of wedge organs may be two, three (in a triangular orientation) or more, depending upon the size and the form of the unit. The tightening device may be constructed in several different ways, for example as a buckle intended for a slalom-skiing boot.

Claims: CLAIMS : 1. Arrangement for releaseable attachment of a unit (1) to an attachment surface (2), said arrangement including a first pair of engagement organs (5, 6) which engage with each other and a second pair of engagement organs (7, 8) which engage with each other, whereby one of the engagement organs in each pair of engagement organs is constructed to be fastened to the attachment surface and the other engagement organ is constructed to be attached to the unit, c h a r a c h t e r i z e d i n that at least one of the engagement organs (5-8) in each pair is constituted by a wedge organ, and that at least one engagement organ (7) in one of the pairs is movably attached in relation to its corresponding engagement organ (8) in the other pair, said movable engagement organ being constructed to be removed from the other engagement organ in the same pair as regards the mounting position and the disassembly position of the unit, said movable engagement organ furthermore being constructed to be tightened to said second engagement organ by means of a tightening device (26) as regards the attachment position of the unit, while at least one rest surface (15) at the unit is in close contact with a rest surface (14) at the attachment surface. 2. Arrangement accordning to claim 1, c h a r a c h t e - r i z e d i n that all of the engagement organs are constituted by wedge organs (5-8). 3. Arrangement accordning to claim 2, at which the attachment arrangement is constructed in such a way that the unit (1) is hanging essentially vertical, c h a r a c ht e r i z e d i n that the pairs of wedge organs are constituted by at least one upper pair of wedge organs (5, 6 ) and one lower pair of wedge organs ( 7 , 8 ) , and that the wedge organ (5) which is included in the upper pair and which is being part of the attachment surface (2) is directed away from the corresponding wedge organ in the lower pair, and that the wedge organ which is included in the upper pair and which is being part of the unit (1) is directed towards the corresponding wedge organ (8) in the lower pair. 4. Arrangement according to claim 3, c h a r a c h t e - r i z e d i n that both wedge organs (5-8) in each pair of wedge organs disclose wedge surfaces (10-13) which are in close contact with each other in pairs in the attachment position, with frictional engagement under one and the same angle (v) in relation to the attachment surface (2). 5. Arrangement according to claim 4, c h a r a c h t e - r i z e d i n that the wedge surfaces (10, 12) of the wedge organs (5, 6) which are part of the attachment surface (2) are essentially directed towards the attachment surface, and that the wedge surfaces (11, 13) of the wedge organs (6, 8) which are part of the unit (1) are essentially directed towards the unit. 6. Arrangement according to claim 4, c h a r a c h t e - r i z e d i n that said support surface (15) at the unit (1) is constituted by a number of flanges (29, 30, 39, 40) which protrude from the unit. 7. Arrangement according to claim 6, c h a r a c h t e - r i z e d i n that the wedge organs ( 5 , 7 ) which are part of the attachment surface (2) are attached to a base structure in the form of an attachment support (18), said attachment support containing at least one profile rail (20, 21) having a base (22) and protruding flanges (23, 24), whereby the base forms said support surface (14) being part of the attachment surface. 8. Arrangement according to claim 7, c h a r a c h t e - r i z e d i n that said flanges (29, 30, 39, 40) at the unit ( 1 ) are constructed to cooperate with laterally directed surfaces of the flanges (23, 24) at the profile rail (20, 21) or with the wedge organs (5, 7) being part of the attachment surface (2), for the purpose of guiding the unit laterally. 9. Arrangement according to claims 1-7, c h a r a c h - t e r i z e d i n that the tightening device (26) is constituted by a screw (32) which is pivotably arranged in the attachment support (18), said screw being in threaded engagement with the movable wedge organ ( 7 ) . 10. Arrangement according to claim 9, c h a r a c h t - e r i z e d i n that a pressure spring (37) is arranged between a fixed part (35) of the attachment support (18) and the movable wedge organ (7), said pressure spring being arranged in order to keep the movable wedge organ in a removed position as regards the mounting position and the disassembly position.

Inventors: BJOERK PETER, JOHANSSON ANDERS, PETTERSSON DAN, SVANTESSON MIKAEL, BJOERK, PETER, JOHANSSON, ANDERS, PETTERSSON, DAN, SVANTESSON, MIKAEL
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1998
Main classification: H05K7
IPC codes: H02B1