Technical field

The present invention relates generally to a floor support device and a floor support system.

Background art

In construction of buildings, it is suitable to position floors such that a spacing is formed between an interior floor structure and an underlying floor structure. This is due to many reasons, among which improved ventilation, the possibility of achieving a more horizontally even floor and improved insulation against sound and vibration are some reasons. Such a floor as often designed to be supported by a system of joists, wherein a joist may be provided with means for receiving e.g. an adjustment screw which in turn is fastened to an underlying floor structure. A floor system like this allows for localized adjustment of height so that any uneven characteristics of the underlying surface is not transferred to the interior floor which is intended for use.

Sometimes it is not possible to position the bars included in the floor support system directly in abutment against an underlying floor structure. This since many types of bars are damaged when resting on a moist support structure and in addition, they obstruct the fee circulation of air between the new and original surface. Furthermore, the underlying support structure is not as a rule completely even, or a certain inclination of the new interior floor surface may be desired.

Furthermore, in the case of multiple story buildings or apartments blocks, by separating the floor which e.g. is walked on and supports heavy objects, such as furniture, such a floor system allows solutions that aims at minimizing the propagation of harmful, disturbing or otherwise unwanted forces and dissipations of energy.

One known bar support system for floor constructions comprises bars and level adjustment screws. The bars being formed with through holes extending transversely in relation to the lengthwise extension of the bars. The level adjustment screws being adapted for attachment in the bars so as to project from the bars as load-carrying legs which legs rest against an underlying floor support structure. An end part of the level adjustment screw is adapted to be attached to the underlying floor surface and a opposite end part is provided with threads which is adapted to engage with internal threads of the sleeves attached to the rod. Further, the sleeves are manually applicable to the bars and the screws are attachable to the sleeves by thread engagement as they are being screwed into the sleeve, during which operation also the length by which the screws project from the bar is adjustable.

One drawback with the bar support system described above is that it does not provide any dampening insulation which aims at minimizing the propagation of harmful, disturbing and otherwise unwanted forces and dissipations of energy.

Thus, there is a need for an improved floor support device and a floor support structure that is cost-efficient, easier to assemble and at the same time provide improved dampening properties.

Summary of invention

An object of the present invention is to provide a floor support device and a floor support system which overcomes the above mentioned drawbacks.

According to at least one exemplary embodiment, there is provided a floor support device for use together with a floor joist. Said floor support device comprises a level adjustment device, a joist attachment device. Further, said level adjustment device comprises a level adjustment screw and an adjustment block. Said level adjustment screw comprises a first part intended to contact an underlying surface and a second part adapted to engage with said adjustment block. Further, said joist attachment device comprises at least one first engagement means and said adjustment block comprises at least one second engagement means, which first and second engagement means are adapted to engage with each other in an assembled state. Further, said joist attachment device comprises an engagement part adapted to be attached to a floor joist. Further, said floor support device comprises a dampening material sandwiched between said adjustment block and said joist attachment device.

According to one exemplary embodiment of the invention, said adjustment block of said floor support device comprises a through hole through which said level adjustment screw may extend, while the height of said floor support device may be adjusted.

According to one exemplary embodiment of the invention, said joist attachment device comprises an abutment portion from which said engagement part extend in an axial direction away from an underlying support surface, which said engagement part is adapted to be attached to a floor joist.

According to one exemplary embodiment of the invention, said first engagement means of said joist attachment device and said second engagement means of said adjustment block are complementary with each other. Said at least one first engagement means may comprise a hook and said at least one second engagement means may comprise an abutment such that said hook is snap-fitted with said abutment or said at least one first engagement means may comprise an abutment and said at least one second engagement means may comprise a hook such that said hook is snap-fitted with said abutment.

According to one exemplary embodiment of the invention, said dampening material may comprise a through hole, through which said level adjustment screw may extend, while the height of said floor support device may adjusted.

According to one exemplary embodiment of the invention, said adjustment block comprises a first abutment surface adapted to abut said dampening material, which said first abutment surface may comprise at least one protrusion which engage with a corresponding opening in said dampening material.

According to one exemplary embodiment of the invention, said at least one protrusion may be a flange extending around said through hole of said adjustment block, this to fix said dampening material at mounting of said floor support device. According to one exemplary embodiment of the invention, said at least one protrusion may be a pin arranged on said abutment surface, which pin may engage with a corresponding opening in said dampening material.

According to one exemplary embodiment of the invention, said joist attachment device may comprise at least one protrusion which engage with a corresponding opening in said dampening material. Said protrusion is arranged to extend around said through hole of said joist attachment device and is arranged to engage with a corresponding opening in said dampening material.

According to one exemplary embodiment of the invention, a floor support system is provided which comprises at least two floor support devices. Further, said floor support system comprises at least one floor joist manufactured of a wood-based material or a square metal profile with a hollow cross section . Said floor joist comprises at least a hole, each of said engagement parts of one of said floor support devices is adapted to engage with said hole of said floor joist.

According to one exemplary embodiment of the invention, said at least one hole of said at least one floor joist comprises an abutment shoulder, which is adapted to engage with said engagement part.

Brief description of drawings

The invention is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 shows a perspective view of a first exemplary embodiment of the present invention,

Fig. 2 shows a perspective view of a first exemplary embodiment of the present invention,

Fig. 3 shows a section view of a first exemplary embodiment of the present invention,

Fig. 4 shows a perspective view of a second exemplary embodiment of the present invention, Fig. 5 shows a perspective view of a second exemplary embodiment of the present invention,

Fig. 6 shows a perspective view of a third exemplary embodiment of the present invention,

Fig. 7 shows a perspective view of a forth exemplary embodiment of the present invention, and

Fig. 8 shows a perspective view of a fifth exemplary embodiment of the present invention.

Description of embodiments

In the description below, various directions may be given with reference to a floor support device assembled to support a floor support system. Example of such directions may be up, down, horizontal, vertical etc. It should be particularly pointed out that the directions for a floor support device according to the invention are with reference to a floor support device which is assembled together with a floor support system and provided on an underlying support surface ready for use. All examples herein should be seen as part of the general description and therefore possible to combine in any way in general terms. Again, individual features of the various embodiments may be combined or exchanged unless such combination or exchange is clearly contradictory to the overall function of the device.

In the following, a detailed description of a floor support device and a floor support system according to the invention is given with reference to Fig. 1-Fig. 8.

In Fig. 1 -Fig. 3 a first exemplary embodiment of a floor support system 2 and at least one floor support device 1 is disclosed. The floor support system 2 may be assembled on top of an underlying support surface 3. The floor support system 2 is adjustable in height in relation to the underlying floor support surface 3. The floor support system 2 comprises at least two floor support devices 1 which are adapted to be attached to at least one floor joist 4 and by means of which floor support devices 1 the floor support system 2 may be adjustable in height above the underlying support surface 3. On top of the floor joists 4 of the floor support system 2 an external surface material 5 may be applied.

The floor joist 4 may be a square metal profile with a hollow cross section or a homogenous wooden joist. The use of joists manufactured of wood-based material reduces the climate impact of built environment by use of sustainable produced wood-based materials in place of other materials. Thus, less energy input us needed to manufacture wood products compared with alternative materials.

The floor joist 4 is provided with apertures 6 into which apertures 6 the floor support devices 1 may engage with the floor joist 4. The apertures 6 may extend between two opposite planar external surfaces 7, 8 of the floor joist 4. Thus, the planar external surfaces of the floor joist 4 are substantially parallel with the underlying floor support surface 3. Further, the aperture 6 may be a through hole. Further, each of the apertures 6 may be provided with an abutment shoulder 9 against which the floor support device 1 may be caused to engage. The abutment shoulder 9 may be configured in such a manner that an upper part 10 of the aperture 6 facing away from the underlying support structure 3 has a larger diameter than a lower portion 11 of the aperture 6.

In the event the floor joist 4 is manufactured of a square metal profile with a hollow cross section, the aperture 6 may be provided on an external side surface which faces the underlying floor support surface 3. Thus, the abutment shoulder is formed by the aperture 6 and an internal side surface parallel with the external side surface of the square metal profile. Further, the aperture may be a through hole extending through the two planar external surfaces of the metal floor joist 4.

The floor support device 1 is adapted for use together with a floor joist 4. The at least one floor support device 1 comprises a level adjustment device 12 and a joist attachment device 13. Further, the level adjustment device 12 is attached to the joist attachment device 13. Further, the joist attachment device 13 is attached to the floor joist 4 in a manner which is to be described in closer detail in the description below. The level adjustment device 12 comprises a level adjustment screw 14 and an adjustment block 15. The level adjustment screw 14 comprises external threads 16 which are adapted to engage with internal threads 17 of the adjustment block 15. The external threads 16 may be provided at least in an upper end of the level adjustment screw 14 facing the adjustment block 15, allowing the level adjustment screw 14 to be screwed into the adjustment block 15. Preferably, the external threads 16 are provided along the full length of the level adjustment screw 14 to allow maximal height adjustment for the floor support system 2 in the event the height fluctuations of the underlying support surface 3 are large, when comparing height difference between different locations of the underlying floor support surface.

The level adjustment screw 14 is hollow and at its end which is intended to be in contact with an underlying floor support surface 3 the level adjustment screw 14 may be provided with a hole 18 for reception therein of a fastener such as screw or nail, by means of which it may be attached to the underlying support structure 3. The hole or cavity in the level adjustment screw 14 may have a hexagonal cross-sectional shape, that is suitable to tool engagement. For example, the cavity may have a hexagonal cross-sectional shape allowing the screw to be turned by means of an Allen wrench. In this manner both the attachment of the level adjustment screw 13 by means of the fasteners and the adjustment of the screws 14 by means of e.g an Allen wrench may be performed from the upper side of the floor joist 4, which in an assembled state is turned away from the underlying support structure 3.

Further, the joist attachment device 13 comprises an abutment portion 19 against which the floor joist 4 is arranged to abut when in an assembled state. The abutment portion 19 comprises a first surface 20 and a second surface 21. The first surface 20 is arranged to face away from the underlying support surface 3 and the second surface 21 is arranged to face the underlying support surface 3 in an assembled state. The abutment portion 19 may comprise one or more first alignment edges 48 which may be provided to align and maintain the floor joist 4 on the joist attachment device 13. The first alignment edges 48 are arranged to protrude in a direction towards the floor joist 4. Further, the first alignment edges 48 are arranged to extend along the edges of the abutment portion 19 which edges extend in the same extension direction as the floor joist 4.

Furhter, the abutment portion may also comprise one or more second alignment edges 49 which may be provided to align and maintain a damping material 29 in abutment with the joist attachment device 13. The second alignment edges 49 are arranged to protrude in a direction towards the underlying floor support surface 3. Further, the first alignment edges 49 are arranged to extend along the edges of the abutment portion 19 which edges extend in the same extension direction as the floor joist 4.

The joist attachment device 13 comprises an engagement part 22 adapted to be attached to the floor joist 4. The joist attachment device 13 may be centrally provided on the abutment portion 19, such that the abutment portion 19 extend outside the engagement part 22, whereupon the floor joist 4 may rest in an assembled state. The engagement part 22 is elongated and provided with at least one locking protrusion 23 intended to engage with the abutment shoulder 9 formed in the aperture 6 of the floor joist 4. Thus, the locking protrusion 23 protrude from an external surface 24 of the engagement part 22.

Further, the engagement part 22 comprises at least one longitudinal slit 25 and is manufactured of a material which may be bent resiliently somewhat outwards and/or inwards. Owing to this arrangement the engagement part 22 may be forced into a hole 6 in a floor joist 4 from the underside thereof, whereby the at least one locking protrusion 23 of the engagement part 22 is forced somewhat towards the center of the aperture 6, until it’s at least one locking protrusion 23 move past the abutment shoulder 9 and snap outwards to lockingly secure the joist attachment device 13.

This fastening arrangement is advantageous since on the one hand it is rapid and simple and on it may be locked and if needed be detached completely manually without the use of tools or with the aid of simple tools only.

The joist attachment device 13 comprises first engagement means 27, which is adapted to engage with second engagement means 28 provided on the adjustment block 15. The first engagement means 27 and the second engagement means 28 may be described as a pair of engagement means. The first engagement means 27 extend from the abutment portion 19 in a direction towards an underlying support surface 3. In the first exemplary embodiment, a first pair of the engagement means is arranged on one first side 32 of the floor support device 1 and a second pair of the first engagement means 27 and the second engagement means 28 is arranged on an opposite second side 33 of the floor support device 1.

The second engagement means 28 of the adjustment block 15 may be complementary shaped to the first engagement means 27, shown in Fig. 2 - Fig. 3. Thus, in the case the first engagement means 27 is hook-shaped then the second engagement means 28 is designed as an abutment 37, around which the hook shaped means 47 may engage. With this configuration, the first engagement means 27 and the second engagement 28 means are snap-fitted engaged with each other.

In all of the aspects and exemplary embodiments described herein, snap-fitted is to be understood as bringing two elements into direct physical contact with each other whereupon they are arranged in a latched position so that the movement of one element at least partially induces movement in the other element, or that movement of one element in at least one direction is restricted by the other element.

In the first exemplary embodiment the second engagement abutment 28 is configured as an abutment 37, which is engaged by the hook-shaped first engagement means 27. Thus, the first engagement means 27 may be snap-fitted to the second engagement means 28. Thus, the first engagement means 27 is elongated and extend from the abutment portion 19 towards the underlying support surface. An end of the first engagement means 27 is freely arranged as a leg and provided with the hook-shaped means 47 in its freely arranged end. The hook shaped means 47 is provided with a substantially flat engagement surface 36 which is adapted to engage with the second engagement means 28. The flat engagement surface 36 is arranged to face the adjustment block 15. Further, the flat engagement surface 36 may be arranged parallel in relation to an underlying floor support surface 3. An exterior surface of the adjustment block 15 may be provided with the second engagement means 28. The second engagement means 28 is arranged as an abutment surface 37 which is substantially parallel to the underlying support surface. In an assembled state the engagement surface 36 and the abutment surface 37 is substantially parallel with each other. Further, the flat engagement surface 36 may be arranged parallel in relation to the abutment surface 37.

Further, the second engagement means 28 may be surrounded by protective edges 31. The protective edges 31 are adapted to protect the first and second engagement means 27, 28 in the event the adjustment block 15, the dampening material 29 and the joist attachment device 13 are assembled before the floor support device are delivered to the construction site where the floor support devices 1 are to be assembled with the floor joist 4 and the level adjustment screw 14. Accordingly, the protective edges 31 protect the first and second engagement means 27, 28 from damages in any event the floor support devices 1 are treated cautiously.

The engagement surface 36 of the first engagement means 27 and the abutment surface 37 of the second engagement means 28 may be arranged in other directions than parallel in relation to the underlying support surface, just as long as the inclination of the abutment surface 37 and the flat engagement surface 36 are substantially the same and provide a locking action.

Further, the floor support device 1 comprises the dampening material 29 which is sandwiched between the adjustment block 15 and the joist attachment device 13.

The dampening material 29 is provided in order to provide resiliency and/or sound reduction in the floor. In an assembled state, the dampening material 29 is provided to abut the second surface 21 of the joist attachment device 13 and a first abutment surface 38 of the adjustment block 15. The first abutment surface 38 is arranged to face away from the underlying support surface, in an assembled state. An external boundary edge of the dampening material 29 may be shaped as the geometrical shape of the abutment surfaces of the adjustment block 15 and the joist attachment device 13. Preferably, the external boundary edge of the dampening material 29 is square shaped or shaped as a rectangle. To allow compression of the dampening material 29, the first engagement means 27 and second engagement means 28 are so designed, that the second engagement means 28 is allowed to slide out of engagement with the first engagement means 27 when the dampening material 29 is compressed e.g. when a high surface load is applied to a certain region of the external floor surface. Thus, the dampening material 29 is compressed in a direction which is substantially perpendicular to the underlying floor support surface 3. Thus, when the first engagement means 27 and the second engagement means 28 are in engagement with each other, the dampening material 29 is expanded to its maximum thickness. When a surface load is applied to the external floor surface the dampening material 29 is compressed to a certain extent. The dampening material 29 may comprise a through hole 39, through which said level adjustment screw 14 may extend, while the height of said floor support device 1 may be adjusted accordingly.

The first abutment surface 38 of the adjustment block 15 may comprise at least one protrusion 40 which engage with a corresponding opening or hole 39 in the dampening material 29. The at least one protrusion 40 may be arranged as a protruding edge around the through hole 30 of the adjustment block 15. Thus, the external diameter of the protrusion 40 is equal to or slightly smaller than the internal diameter of the through hole 39 within the dampening material 29. Further, the second surface 21 of the joist attachment device 13 may also be provided with at least one protrusion 42 which engage with a corresponding opening or hole 39 in the dampening material 29. The protrusion 42 may be arranged as a protruding edge around the through hole 26 of the joist attachment device 13. Thus, the external diameter of the protrusion 42 is equal to or slightly smaller than the internal diameter of the through hole 39 within the dampening material 29. An advantage with the protrusions 40, 42 is that the dampening material 29 is held in place during assembly and use of the floor support device 1.

Depending on the dampening degree desired, the thickness of the dampening material 29 may be varied, thus the length of the first engagement means 27, and the position of the second engagement means 28 may be varied accordingly. The adjustment block 15, the dampening material 29 and the joist attachment device 13 are so designed such that the level adjustment screw 14 may be freely movable within these such that the level adjustment may be adjusted to the desired level. Thus, the adjustment block 15, the dampening material 29 and the joist attachment device 13 may be provided or arranged such that the level adjustment screw 14 may be levelled within these.

At designing of the geometrical shape of the dampening material, it is desirable that the material waste is limited to a minimum as the dampening material is costly to purchase from manufacturers. Thus, the less material needed to be cut away to obtain the final geometrical shape, the cheaper manufacture of the floor support device and floor support system.

In one exemplary embodiment, the at least one first engagement means 27 may comprise an abutment provided on the joist attachment device 13 and said at least one second engagement means 28 may comprise a hook provided on the adjustment block 15 such that said hook is snap-fitted with said abutment.

In Fig. 4 - Fig. 5 a second exemplary embodiment of the floor support device 101 is described. As the first exemplary embodiment, the floor support device according to the second exemplary embodiment comprises a level adjustment screw 114, an adjustment block 115, a damping material 129 and a joist attachment device 113. The floor support device 101 according to the second exemplary embodiment comprises at least a pair of engagement means. In the second exemplary embodiment the pair of engagement means comprises a first engagement means 127 and a second engagement means 128. The first engagement means 127 may be integrated with an abutment portion 119 of the joist attachment device 113. In this exemplary embodiment the abutment portion 119 may be designed with first and second flanges 150, 151 which extend from the abutment portion 119, and thus constitute a U-shape which is upside down. The first and second flanges 150, 151 may be provided with openings 152, 153 which provide abutment for the second engagement means 128. The second engagement means 128 are provided on the sides of the adjustment block 115 and are designed as protrusions which extend from the sides. Thus, the second engagement means 128 protrude and engage with the openings 152, 153, from the inside of the first and second flanges 150, 151. Hence, the protrusions may be resilient and be bent somewhat outwards and/or inwards to allow a snap-fit upon assembly or disassembly.

In Fig. 6 a third exemplary embodiment of the floor support device 201 is described. As the first exemplary embodiment, the floor support device 201 according to the third exemplary embodiment comprises a level adjustment screw 214, an adjustment block 215, a damping material 229 and a joist attachment device 213.

Within this third exemplary embodiment the adjustment block 215 and the damping material 229 are slightly different designed compared to the first exemplary embodiment. Within the third exemplary embodiment, the adjustment block 215 is provided with at least two protrusions 243, 244, which are provided on the first abutment surface 238 of the adjustment block 215. The dampening material 229 may be designed to constitute two pieces, and each piece comprises at least one aperture 245, 246 each, which is arranged to engage with the protrusion 243, 244 of the adjustment block 215. The at least two protrusions 243, 244 and the apertures 245, 246 in the dampening material 229 secure the dampening material 229 in place during assembly and use of the floor support device 201.

To keep the damping material 229 in place during assembly and use, the abutment portion 238 of a first abutment surface of the adjustment block 215 may be provided with one or more alignment edges 254 which may be provided to align and maintain the dampening material 229 in position on the adjustment block 215 during use and assembly. The alignment edges 254 are arranged to protrude in a direction towards the floor joist. Further, the alignment edges 254 may extend partially or along the full length of the edges of the abutment portion 238.

In Fig. 7 a forth exemplary embodiment of the floor support device 301 is described. As the first exemplary embodiment, the floor support device according to the forth exemplary embodiment comprises a level adjustment screw 314, an adjustment block 315, a damping material 329 and a joist attachment device 313.

Within this forth exemplary embodiment the joist attachment device 313 comprises first engagement means 327, which is adapted to engage with second engagement means 328 provided on the adjustment block 315. The first engagement means 327 and the second engagement means 328 may be described as a pair of engagement means. The first engagement means 327 extend from the abutment portion 338 in a direction towards an underlying support surface. In the fourth exemplary embodiment, two pairs of the engagement means are arranged on one first side 332 of the floor support device 301 and two second pairs of the engagement means are arranged on an opposite second side 333 of the floor support device 201.

Thus, the first engagement means 327 may be hook-shaped and the second engagement means 328 may be shaped as abutments. The abutments may be provided on a side surface of the adjustment block 315 or the lower edges 328 of the adjustment block 315 may act as abutment portions.

Thus, within this fourth exemplary embodiment the joist attachment device 313 and the adjustment block 315 may comprise four first engagement means 327 and four second engagement means 328. Whereof, two of the first engagement means 327 and two of the second engagement means 328 are provided on the same side 332 of the joist attachment device 313, and two of the first engagement means 327 and two of the second engagement means 328 are provided on the opposite side 333 of the joist attachment device 313.

Thus, in the fourth exemplary embodiment, two pairs of engagement means are arranged on one first side 332 of the floor support device 301 and two second pairs of engagement means are arranged on an opposite second side 333 of the floor support device 301.

In Fig. 8 a fifth exemplary embodiment of the floor support device 401 is described. As the first exemplary embodiment, the floor support device 401 according to the fifth exemplary embodiment comprises a level adjustment screw 414, an adjustment block 415, a damping material 429 and a joist attachment device 413.

In the fifth exemplary embodiment the joist attachment device 413 and the adjustment block 415 may comprise four pairs of engagement means, and each pair of engagement means comprises a first engagement means 427 and a second engagement means 428. Whereof, the first pair of engagement means is provided on one first side 432 of the joist attachment device 413, and a second pair of engagement means is provided on a second opposite side 433 of the joist attachment device 413, seen in relation to the first side 432 of the joist attachment device413. Further, a third pair of engagement means is provided on a third side 434 of the joist attachment device 413, and a forth pair of engagement means is provided on a forth opposite side 435 of the joist attachment device 413, this in relation to the third side 434 of the joist attachment device 413.

In other words, in the fifth exemplary embodiment, one pair of engagement means is arranged on a first side 432 of the joist attachment device 413 and a second pair of engagement are arranged on an opposite second side 433 of the joist support device 413. Further one pair of engagement means is arranged on a third side 434 of the joist engagement device 413 and one pair of engagement means is arranged on a forth opposite side 435 of the joist engagement device 413.

Upon mounting of the floor support device 1 ; 101, 201 ; 301 ; 401 ; the joist attachment device 13; 113; 213, 313; 413 is attached from the underside of the floor joist 4.

Thus, the engagement part 22 is introduced into the aperture 6 and the at least one locking protrusion 23 is arranged to engage the abutment portion 19. The dampening material 29; 129; 229; 329; 429 is arranged upon the adjustment block 15; 115; 215; 315; 415 and may be held in place by means of the protrusion(s) 40; 42; 243,244, where after the adjustment block 15; 115; 215; 315; 415 together with the dampening material 29; 129; 229; 329; 429 is snap-fitted onto the joist attachment device 13;

213; 213; 313; 413. Further, the level adjustment screw 14; 114; 214; 314; 414 is introduced into the adjustment block 15; 115; 215; 315; 415, and the external threads 17 of the adjustment block 15; 115; 215; 315; 415 such that a height adjustment of the floor support device 1 ; 101; 201 ; 301 ; 401 may be performed when the level adjustment screw 14 is turned accordingly. The level adjustment screw 14 may be turned by means of a suitable tool, which tool may easily be applied from above to engage with an internal side of the level adjustment screw 14. The above mounting steps may be performed in any consecutive order.

The above described exemplary embodiments are possible to combine in any way in general terms. Again, individual features of the various exemplary embodiments may be combined or exchanged unless such combination or exchange is clearly contradictory to the overall function of the device.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed exemplary embodiments.

Other variations to the disclosed exemplary embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.