Technical field

The present invention concerns a fastening insert for fastening a component of an elevator to a cast-in-place concrete wall, as defined in claim 1 . The invention further relates to a use of a fastening insert and a method of installing a guide rail of an elevator, as defined in the other independent claims.

Background

The walls of elevator shafts are typically made of concrete. Various components of the elevator and also other equipment need to be fastened to the walls of the elevator shaft. For example, guide rails of the elevator car and/or the counterweight are attached to the walls of the elevator shaft. Also the doors of the landings of the elevator are attached to the walls. The shaft can also be provided with for instance ladders for facilitating service of the elevator.

The elevator shafts can be cast-in-place structures. For example slip forming or jump forming can be used for casting the shafts. In both methods, the formwork used for casting is raised during the construction until the desired height of the structure is reached. The difference between slip forming and jump forming is that slip forming is a continuous process where the formwork rises continuously, whereas in jump forming the casting is done in batches and the formwork is lifted in predetermined steps.

In conventional methods of fastening various components, such as the guide rails, to the walls of the elevator shaft, holes are drilled into the walls and the components are fastened to the drilled holes using suitable fastening means, such as wedge anchors.

Drilling of the concrete walls involves several disadvantages. For instance, the dust produced by the drilling forms an occupational safety risk to the workers exposed to the dust. The drilling can also cause strain injuries. Furthermore, the dust can prevent starting or completing other construction work, such as installation of ventilation systems, or at least protecting other parts of the buildings from the dust may be necessary. In addition, automation of the installation of elevator components is not problem-free in case the installation requires drilling. Drilling in the elevator shaft cannot be started before completion of the construction of the shaft and the installation requires multiple tool changes and supply of fastening means. This makes automated installation arrangements complex and expensive.

An alternative for drilling is to use C-shaped profiles, which are arranged in the wall before casting. After casting of the wall, a T-bolt can be arranged in a groove of the profile. Although drilling can be avoided, the use of C-profiles has several disadvantages. For instance, installing of T-bolts requires precision and would be difficult to automate. Also, the bolts and nuts need to be supplied and mounted after casting of the wall, which complicates the process of installing the elevator components.

Summary

An object of the present invention is to provide a fastening insert for fastening a component of an elevator to a cast-in-place concrete wall of an elevator shaft, as defined in claim 1 . Another object of the invention is to provide a use of such a fastening insert to attach a guide rail or a landing door of an elevator to a wall of an elevator shaft, as defined in another independent claim. A further object of the invention is to provide an improved method of installing a guide rail of an elevator to a cast-in-place concrete wall of an elevator shaft, as defined in a third independent claim.

The fastening insert according to the invention is configured to be attached to reinforcing elements of the wall before casting of the wall and comprises a plate element that is configured to be arranged within the wall in parallel with the wall, a fixing element that is configured to extend in a mounted position of the fastening insert within the wall in a direction that is perpendicular to the wall, the fixing element comprising a thread that is configured to cooperate with a thread of a threaded fastening element for fastening a component of the elevator to the wall of the elevator shaft, and a threaded fastening element engaged with the thread of the fixing element. The fastening insert is configured to accommodate the threaded fastening element during casting of the wall and to allow the threaded fastening element to be unscrewed or pulled out after casting of the wall to a position at least partly outside the wall to allow mounting of the component of the elevator. The fastening insert according to the invention allows different components of an elevator to be easily attached to the walls of the elevator shaft without a need to drill the wall after casting of the wall. This reduces occupational safety risks and also facilitates automation of installation of components, such as guide rails. Because the fastening insert comprises the threaded fastening element, there is no need to install the fastening elements after casting of the wall. Supply and mounting of fastening elements, such as bolts, after casting can thus be avoided. This provides a significant benefits for both manual and automated installation of components. The installation is simpler and easier to automate.

The method according to the invention comprises the steps of attaching a plurality of fastening inserts defined above to reinforcing elements of the wall, each fastening insert being attached to the reinforcing element before casting of the respective portion of the wall, casting the wall of the elevator shaft, and attaching the guide rail to the fastening inserts directly or indirectly.

According to an embodiment of the invention, the fixing element is configured to be before casting of the wall moveable in relation to the plate element in a direction that is perpendicular to the wall. This allows simple positioning of the parts of the fastening insert after attaching the fastening insert to the reinforcing elements of the wall.

According to an embodiment of the invention, the thread of the fixing element is an internal thread. The threaded fastening element can thus be a bolt or a threaded rod.

According to an embodiment of the invention, the fixing element comprises a flange that is configured to anchor the fixing element in the cast wall. The flange ensures reliable anchoring of the fastening insert. However, also the plate element could anchor the fastening insert, or the fastening insert could be provided with some other elements attached to or integrated with the plate element or the fixing element to ensure reliable anchoring.

According to an embodiment of the invention, the fastening element is a bolt, such as a flange bolt.

According to an embodiment of the invention, the fixing element is provided with an external thread and the plate element comprises a hole that is provided with an internal thread that is configured to be engaged with the external thread of the fixing element for attaching the fixing element to the plate element. The threads allows adjusting of the relative positions of the plate element and the fixing element and maintaining the positions during casting of the wall.

According to an embodiment of the invention, the fastening insert comprises a cavity extending in a mounted position of the fastening insert inwards from the outer surface of the fastening insert and being configured to accommodate at least part of the threaded fastening element during casting of the wall. The cavity can thus accommodate for instance the head of a bolt. This allows the fastening element to be connected to the fixing element before casting of the wall.

According to an embodiment of the invention, the fastening insert comprises a protective sleeve that is arranged around the fixing element and configured to accommodate at least part of the threaded fastening element during casting of the wall. This allows that the fixing element does not need to extend to the wall surface.

According to an embodiment of the invention, the fastening insert comprises a removeable or breakable cover element that is configured to close the space accommodating the threaded fastening element during casting of the wall and to be removed or broken after the casting to gain access to the threaded fastening element. The cover element ensures that the thread of the fixing element and the fastening element remain functional.

According to an embodiment of the invention, the fastening insert comprises at least two fixing elements arranged at a distance from each other. By arranging at least two fixing elements into a single fastening insert, two or more fastening points at predetermined distances from each other can be provided.

According to an embodiment of the invention, the method comprises a step of unscrewing or pulling out the threaded fastening elements after casting of the wall to a position at least partly outside the wall to allow mounting of the component of the elevator. Brief description of the drawings

Embodiments of the invention are described below in more detail with reference to the accompanying drawings, in which

Fig. 1 shows schematically an elevator shaft,

Fig. 2 shows a fastening insert according to an embodiment of the invention,

Fig. 3 shows the fastening insert of Fig. 2 with cover elements,

Fig. 4 shows parts of the fastening insert of Fig. 2,

Fig. 5 shows a protective sleeve of the fastening insert of Fig. 2,

Fig. 6 shows a fastening insert according to another embodiment of the invention,

Fig. 7 shows the fastening insert of Fig. 6 with cover elements,

Fig. 8 shows parts of the fastening insert of Fig. 6,

Fig. 9 shows the fastening insert of Fig. 2 attached to the reinforcing elements of a wall before casting of the wall,

Fig. 10 shows the fastening insert of Fig. 6 attached to the reinforcing elements of a wall before casting of the wall,

Fig. 1 1 shows positioning of the fastening insert of Fig. 6 within a formwork,

Fig. 12 shows a view of the fastening insert of Fig. 2 in a cast wall,

Fig. 13 shows a view of the fastening insert of Fig. 6 in a cast wall,

Fig. 14 shows a view of the fastening insert of Fig. 2 in a cast wall prepared for mounting of a component of an elevator,

Fig. 15 shows a view of the fastening insert of Fig. 6 in a cast wall prepared for mounting of a component of an elevator,

Fig. 16 shows a tool for cutting cover elements and unscrewing fastening elements, Fig. 17 show a step of opening a fastening element,

Fig. 18 shows as a flowchart the method according to the invention, and

Fig. 19 shows an apparatus for installing guide rail brackets.

Detailed description

Figure 1 shows schematically an elevator shaft of an elevator. The elevator shaft is provided with guide rails 10. The guide rails 10 are configured to guide an elevator car (not shown) moving in the vertical direction in the elevator shaft. Similar guide rails could be provided for a counterweight of the elevator. Each guide rail 10 comprises a plurality of guide rail segments 10a. The guide rails 10 are attached to the walls of the elevator shaft by means of brackets 7. The brackets 7 are thus attached to the walls and the guide rails 10 are attached to the brackets 7. Each bracket 7 is attached to the wall by means of two or more fastening elements. The fastening elements can be, for instance, bolts.

The elevator shaft is a cast-in-place structure that is made of reinforced concrete. The elevator shaft can be formed for example using a slip form or jump form technique. Slip forming and jump forming are typically used in the construction of tall buildings and other tall structures. In both methods, concrete is poured into a formwork (mold) that is provided with reinforcing elements, such as reinforcing bars.

The formworks used for slip forming or jump forming are low, and the formworks are raised as the construction work progresses. In slip forming, the formwork rises continuously at a speed that allows the lower part of the cast structure to achieve sufficient strength to support the upper part of the structure. In jump forming, the formwork is filled with concrete and the formwork is lifted when the cast portion has reached a sufficient strength to allow lifting of the formwork. The formworks used in slip forming or jump forming can be lifted using a crane, but often the formworks are self-climbing.

When slip forming or jump forming is used, the cast walls cannot comprise parts protruding outwards from the wall, because the protruding parts would prevent moving of the formwork. The fastening insert according to the invention can be used in cast-in-place concrete walls that have been constructed using slip forming or jump forming. The fastening insert according to the invention can be used for fastening components of an elevator to the wall of an elevator shaft. Such components include, but are not limited to, guide rails for an elevator car and/or a counterweight, brackets for fastening the guide rails, and landing doors of the elevator.

Figures 2 and 3 show a fastening insert 1 according to an embodiment of the invention and figures 4 and 5 show parts of the fastening insert 1 of figures 2 and 3.

The fastening insert 1 comprises a plate element 2. In the embodiments of the figures, the plate element 2 is an elongated part. The plate element 2 is configured to be arranged within the wall in parallel with the wall. In a cast wall, the plate element 2 does not protrude out of the wall. In case of an elongated plate element 2, the plate element 2 can be arranged within the wall such that the longitudinal direction of the plate element 2 is parallel with the horizontal direction. In the embodiment of figures 2 and 3, the plate element 2 is configured to be attached to reinforcing elements of the wall. In the embodiment of figures 2 and 3, the plate element 2 functions as an anchoring element that firmly anchors the fastening insert 1 to the wall. The plate element

2 can be a metal plate, such as a steel plate. In the embodiment of figures 2 and 3, the plate element 2 is made of sheet metal. The thickness of the plate element 2 can be, for instance, in the range of 2-5 mm. In the embodiment of figures 2 and 3, the plate element 2 comprises holes 2a, which can be utilized for attaching the fastening insert 1 to reinforcing elements of the wall.

The fastening insert 1 further comprises a fixing element 3. The fixing element

3 is configured to extend in a mounted position of the fastening insert 1 within the wall in a direction that is perpendicular to the wall. In a cast wall, the fixing element 3 does not protrude out of the wall. The fixing element 3 is connected to the plate element 2. The fixing element 3 is configured to cooperate with a threaded fastening element 5 for fastening a component of the elevator to the wall of the elevator shaft. The fixing element 3 thus allows components of the elevator to be attached to the wall of the elevator shaft without a need to drill the wall after casting of the wall. The fixing element 3 is preferably made of steel. The fastening insert 1 is configured to accommodate the threaded fastening element 5 during casting of the wall and to allow the threaded fastening element 5 to be unscrewed or pulled out after casting of the wall to a position at least partly outside the wall to allow mounting of the component 7 of the elevator. Within the fastening insert 1 is thus formed a space that can accommodate the fastening element 5 during casting of the wall. This allows the threaded fastening element 5 to be engaged with the thread of the fixing element 3 before casting of the wall. This simplifies the process of installing components of the elevator, because there is no need to supply the fastening elements when the components are being fastened to the wall.

In the embodiment of figures 2 and 3, the fixing element 3 is configured to be moveable relative to the plate element 2 before casting of the wall. The plate element 2 is provided with a hole, through which the fixing element 3 is inserted. The fixing element 3 can move in a direction that is in a mounted position of the fastening insert 1 perpendicular to the wall. In the embodiment of figures 2 and 3, the fixing element 3 comprises a cylindrical portion and a flange 3a arranged at an end of the cylindrical portion. The cylindrical portion is inserted through the hole of the plate element 2. The flange 3a has a larger diameter than the hole, and the flange 3a thus prevents the fixing element 3 from being completely pulled out from the plate element 2. The fixing element 3 could also have some other external shape than a cylindrical shape, but a round shape reduces the risk that cavities are formed within the cast of the wall.

In the embodiment of figures 2 and 3, the fixing element 3 is provided with an internal thread 3b that is configured to cooperate with the threaded fastening element. The thread is arranged in a blind hole.

In the embodiment of the figures, the threaded fastening element is a flange bolt 5. A benefit of using a flange bolt 5 as the threaded fastening element is that additional fastening parts are not necessary. That makes installation of the components of the elevator simple.

However, the threaded fastening element 5 could also be some other kind of bolt. Furthermore, the threaded fastening element 5 does not need to be a bolt. The threaded fastening element 5 could also be a threaded rod. In case of a threaded rod, the outer end would preferably be provided with a shape allowing the rod to be engaged with a tool for rotating the rod. For instance, the end could be provided with a hexagonal socket for rotating the rod with a hex key. If the threaded fastening element was a threaded rod, a nut or a similar additional fastening part would be needed to fasten a component of the elevator to the fastening insert 1 .

In the embodiment of figures 2 and 3, the fastening insert 1 comprises a protective sleeve 4. The protective sleeve 4 is arranged around the outer end of the fixing element 3. The protective sleeve 4 is dimensioned so that the threaded fastening element 5 can be screwed into the fixing element 3 such that it does not extend beyond the protective sleeve 4. In the embodiment of figures 2 and 3, the protective sleeve 4 thus forms a space accommodating the threaded fastening element 5 during casting of the wall. The protective sleeve 4 is further dimensioned so that the threaded fastening element 5 can be rotated with a suitable tool when the protective sleeve 4 is around the fixing element 3. The protective sleeve 4 is configured so that it can retain its shape during casting of the wall. Preferably, the protective sleeve 4 is configured to be moveable in the longitudinal direction of the fixing element 3. The protective sleeve 4 can be made of, for instance, a plastic material.

The fastening insert 1 is further provided with a cover element 6. The cover element 6 is configured to close the outer end of the protective sleeve 4. The cover element 6 is configured so that it can be easily removed or broken after casting of the wall. The cover element 6 could be made of for example plastic material or of a thin metal sheet. The cover element 6 could be an integral part of the protective sleeve 4.

In the embodiment of figures 2 and 3, the protective sleeve 4 and the cover element 6 form together with a surface of the fixing element 3 a closed cavity. During casting of the wall, the cavity accommodates the head of the flange bolt 5. The fastening insert 1 of figures 2 and 3 can thus be provided with the bolts 5 before casting of the wall. This simplifies the installation process of the components of the elevator, because additional fastening elements do not need to be supplied when the components are being attached to the fastening inserts 1 .

Figures 6-8 show a fastening insert 1 according to another embodiment of the invention. Also in this embodiment, the fastening insert 1 comprises a plate element 2 and a fixing element 3. In this embodiment, the plate element 2 is thicker than in the embodiment of figures 2 and 3. This allows the fixing element 3 to be fastened with threads to the plate element 2. The plate element 2 is provided with a hole 2b that is configured to receive one end of the fixing element 3. The hole 2b is provided with an internal thread 2c. The fixing element 3 is provided with a corresponding external thread 3c.

Also in the embodiment of figures 6-8, the fixing element 3 comprises a flange 3a. The flange 3a is arranged at the free end of the fixing element 3. The flange 3a functions as an anchoring element. In the cast wall, the flange 3a thus anchors the fixing element 3 firmly within the wall. Before casting of the wall, the flange 3a can be utilized for fastening the fastening insert 1 to reinforcing elements of the wall.

Also in the embodiment of figures 6-8, the fixing element 3 is provided with an internal thread, which can be engaged with a threaded fastening element. In the embodiment of the figures, the threaded fastening element is a flange bolt 5.

In the embodiment of figures 6-8, the plate element 2 is dimensioned so that the threaded fastening element 5 can be screwed into the fixing element 3 such that it does not extend beyond the plate element 2. The plate element 2 comprises a cavity 2d, which can accommodate the head of the flange bolt 5. The cavity 2d is dimensioned so that the bolt 5 can be screwed using a suitable tool.

In the embodiment of figures 6-8, the fastening insert 1 is provided with a cover element 6, which is configured to cover the threaded fastening element 5 during casting of the wall. The cover element 6 closes the cavity 2d of the plate element 2. The cover element 6 can be, for instance, a plastic foil or tape that can be removed or pierced after casting of the wall.

In the embodiments of the figures, the fastening insert 1 comprises two fixing elements 3 that are arranged at a distance from each other. A threaded fastening element 5 is attached to each fixing element 3. Each fastening insert 1 can thus be utilized for fastening a component of the elevator with two threaded fastening elements 5 to the wall of the elevator shaft. For instance, a bracket of a guide rail 10 of the elevator could be fastened with two bolts to one fastening insert 1 . A fastening insert 1 with two fixing elements 3 facilitates installing of the components, as two fastening points are always arranged at the same distance from each other. In some applications, the fastening insert

1 could comprise even further fixing elements 3.

Next the use of the fastening insert 1 will be described in more detail. Figure 9 shows a perspective view of the fastening insert 1 of figures 2 and 3 attached to reinforcing elements of a wall. Figure 10 shows a similar view of the fastening insert 1 of figures 6-8.

The wall is provided with reinforcing elements 8 that are in the cast wall completely within the concrete structure. The reinforcing elements 8 are steel bars, which can be part of a reinforcing mesh. For instance steel wire can be used for attaching the fastening inserts 1 to the reinforcing elements 8.

In the embodiment of figure 9, the plate element 2 of the fastening insert 1 is attached to the reinforcing elements 8. The fastening insert 1 is attached to the reinforcing elements 8 by means of steel wire (not shown). The holes 2a of the plate element 2 can be utilized for attaching the fastening insert 1 to the reinforcing element 8. However, it is not necessary to provide the plate element

2 with the holes 2a. In the embodiment of figure 9, the fastening insert 1 is positioned so that in the cast wall the plate element 2 is completely enclosed by the concrete. In the embodiment of figure 9, the plate element 2 is arranged behind the reinforcing elements 8. This ensures that the fastening insert 1 is firmly anchored to the wall. However, the plate element 2 could also be arranged on the other side of the reinforcing elements 8.

In the embodiment of figure 10, the fastening insert 1 is attached to the reinforcing elements 8 of the wall via the fixing elements 3. Figure 1 1 shows a side view of the fastening insert 1 of figure 10. Also part of the formwork 9 that is used during casting is shown. In the embodiment of figures 10 and 1 1 , the position of the plate element 2 relative to the fixing elements 3 is adjusted so that the plate element 2 is in contact with the form 9. In the cast wall, the outer surface of the plate element 2 is thus aligned with the wall surface. Because of the threaded connection between the plate element 2 and the fixing element 3, the position of the plate element 2 can be adjusted after the fixing element

3 has been attached to the reinforcing elements 8 of the wall. In the embodiment of figure 9, the positions of the fixing elements 3 and/or the protective sleeves 4 relative to the plate elements 2 are adjusted before casting of the wall. The outer ends of the protective sleeves 4 are arranged against the formwork 9.

Figure 12 shows how the wall with a fastening insert 1 according to the embodiment of figures 2 and 3 looks after casting of the wall. Figure 13 shows a similar view for the fastening insert 1 of figures 6-8. In figure 12, only the cover elements 6 and the end surfaces of the protective sleeves 4 are visible. In figure 13, both the cover elements 6 and the outer surface of the plate element 2 are visible.

Many modifications of the fastening insert 1 are possible. For instance, the fixing elements 3 could be attached to the plate elements 2 in a fixed manner, for instance by welds. The fixing elements 3 could be rods provided with external threads. In that case, a different type of threaded fastening element would be needed. A fastening insert 1 comprising a rod with an external thread as a fixing element 3 could comprise a similar protective sleeve 4 as the fastening insert of figures 2 and 3.

The fixing element 3 could be configured to be moveable relative to the plate element 2 also after casting of the wall. For instance, the fixing element could be a rod having a flange at an inner end and a thread at an outer end. The fixing element could be arranged to move within a sleeve-like part such that during casting of the wall the fixing element would be pushed into an inner position, where the fastening insert accommodates the fixing element, and after casting the fixing element could be pulled to an outer position, where the threaded end protrudes out of the wall. The threaded fastening element could be a nut-type part.

In the embodiments of the figures, the fixing elements 3 could be made without the flanges 3a. The embodiment of figures 6-8 could be modified so that the cavity for the head of the bolt is formed into the fixing element 3.

For fastening components of an elevator to the wall, the cover elements 6 need to be removed or broken. Figure 14 shows the fastening insert 1 of the embodiment of figure 12 ready for mounting a component. Figure 15 shows a similar view of the fastening insert 1 of the embodiment of figure 13. In both figures, the cover elements 6 have been removed and the threaded fastening elements, which are in the embodiments of the figures flange bolts 5, have been screwed partly out from the fixing elements 3. This allows a component with suitably dimensioned slots to be lowered onto the flange bolts 5, after which the flange bolts 5 can be tightened.

Figure 16 shows part of a tool 1 1 that is suitable for cutting the cover elements 6 and for unscrewing and screwing in the threaded fastening elements 5. The tool 1 1 comprises a cutting edge 1 1 a arranged at one end of the tool 1 1 . The cutting edge 1 1 a is configured to break the cover element 6 that is made of for example a plastic material when the tool 1 1 is pressed against the cover element 6. The tool 11 further comprises an internal shape 1 1 b, such as a hexagonal shape, that is configured to be engaged with a corresponding shape of the threaded fastening element 5. Figure 17 shows the use of the tool 1 1 of figure 16.

The method according to the invention for installing a guide rail 10 of an elevator to a cast-in-place concrete wall of an elevator shaft comprises the following steps:

- attaching a plurality of fastening inserts 1 to the reinforcing elements 8 of the wall, each fastening insert 1 being attached to the reinforcing element 8 before casting of the respective portion of the wall 101 ,

- casting the wall of the elevator shaft 102,

- attaching the guide rail 10 to the fastening inserts 1 directly or indirectly 103.

Before attaching a fastening insert 1 to a reinforcing element 8, the reinforcing element 8 has been arranged in place.

For each portion of the wall comprising a fastening insert 1 , the steps of the method are carried out in the order disclosed above. However, it is not necessary to carry out a certain step for the whole wall before proceeding to the following step. For instance, all the steps listed above can be carried out for a certain portion of the wall, and then the steps can be carried out for a subsequent portion of the wall. Alternatively, the steps of attaching the fastening inserts 8 and casting the wall could be repeated for portions of the wall, and the guide rail 10 could be attached to the wall after casting of the whole wall has been completed. Also, the method could be applied after the reinforcing elements 8 for the whole wall have been arranged in place, or, alternatively, the construction of the reinforcing structure could take place simultaneously or alternately with the method according to the invention.

Depending the on the type of the guide rail 10, guide rail segments could be attached to the fastening inserts 1 either directly or via brackets 7 or other intermediate parts.

The fastening inserts 1 are be provided with the threaded fastening elements, such as flange bolts, before casting of the wall. The bolts or other fastening elements are thus ready for installation of the guide rail immediately after casting of the wall, which simplifies the installation.

After casting of the wall and before attaching the guide rail or guide rail bracket, the threaded fastening elements are unscrewed or pulled out to a position at least partly outside the wall to allow mounting of the component of the elevator. This step can be preceded by breaking or removing a cover element protecting the threaded fastening element.

Figure 19 shows an example of an apparatus for installing the brackets 7 of a guide rail 10. The apparatus comprises a frame 12. The frame 12 is provided with guide wheels 14, which are configured to support the frame 12 against the walls of an elevator shaft. The frame 12 is attached to a hoisting member 13, such as a cable. By means of the hoisting member 13, the apparatus can be lifted and lowered in the elevator shaft.

The apparatus is provided with means for detecting the location of the fastening inserts 1 in the shaft. The means for detecting the location of the fastening inserts 1 can be based on, for instance, machine vision or one or more sensors.

The apparatus is further provided with means 15 for removing or breaking the cover elements 6 of the fastening inserts 1 and for unscrewing the threaded fastening elements 5. The means 15 can comprise for instance the tool 1 1 shown in figures 16 and 17. The apparatus can be further configured to arrange the brackets 7 of the guide rails 10 in place.

The apparatus of figure 19 can be used as part of automated installation of the guide rails 10. It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may vary within the scope of the appended claims.