THERMALLY RELEASABLE FASTENING ELEMENT, IN PARTICULAR FOR FASTENING A DOOR ACTUATOR

Abstract

A thermally releasable fastening element, in particular for fastening a door actuator, includes a base body, which is designed to be inserted into a recess or a number of aligned recesses, a core inserted into the base body, at least partially made of a shape memory material, wherein the base body has an unstable area, which is stabilized by the core, and wherein the core is designed to withdraw at least partially from the unstable area upon thermal activation of the shape memory material.

Claims

1. A thermally releasable fastening element for fastening a door actuator, the fastening element comprising: a base body configured to be inserted into a recess or a plurality of aligned recesses, a core inserted into the base body, at least partially made of a shape memory material, wherein the base body has an unstable area, which is stabilized by the core, and wherein the core is designed to withdraw at least partially from the unstable area upon thermal activation of the shape memory material.

2. The fastening element according to claim 1, wherein the unstable area has at least one slot.

3. The fastening element according to claim 2, wherein the unstable area is divided into a plurality of segments by a plurality of slots.

4. The fastening element according to claim 1, wherein the unstable area is formed at one end of the base body.

5. The fastening element according to claim 1, wherein the core, extends over at least 50%, of an axial length of base body.

6. The fastening element according to claim 1, wherein the core is fixedly connected to the base body at an end facing away from the unstable region or is designed for fixed connection to the base body.

7. The fastening element according to claim 1, wherein the base body is designed as a screw with an external thread at least in the unstable area.

8. The fastening element according to claim 1, wherein the base body is designed as an expansion dowel and the core as an expanding mandrel.

9. A door actuator assembly comprising a door actuator and at least one fastening element according to claim 1 for fastening the door actuator.

10. A door assembly, comprising a door and a door actuator assembly according to claim 9, wherein the door actuator is fastened to the door with the at least one fastening element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The disclosure will now be described further on the basis of two exemplary embodiments, in which is shown:

[0025] FIG. 1 a door assembly according to the disclosure with a door actuator assembly according to the disclosure and fastening elements according to the disclosure in accordance with all exemplary embodiments.

[0026] FIGS. 2 and 3 the fastening element according to the disclosure before thermal activation in accordance with a first exemplary embodiment,

[0027] FIGS. 4 and 5 the fastening element according to the disclosure after a thermal activation in accordance with the first exemplary embodiment,

[0028] FIG. 6 the fastening element according to the disclosure in different states in accordance with a second exemplary embodiment, and

[0029] FIG. 7 the detail VII marked in FIG. 6.

DETAILED DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 shows a door assembly 200 for all exemplary embodiments. The door assembly 200 comprises a door 201, of which the door leaf is shown schematically. This door 201 forms a mounting surface with the associated mounting axis 101. FIG. 1 also shows a door actuator assembly 100. The door actuator assembly 100 comprises a door actuator 102, an optional mounting plate 104 and fastening elements 1.

[0031] The door actuator 102 has an output shaft 103, shown purely schematically. The door actuator 102 is connected to the frame or wall in the usual manner via this output shaft 103 and an associated linkage. The linkage can be designed here as a scissor linkage or slide rail linkage.

[0032] FIG. 1 shows purely schematically a plurality of fastening elements 1, which extend parallel to the mounting axis 101 and are used to fasten the door actuator 102 to the door 201. It is provided that the fastening elements 1 are used either to fasten the door actuator 102 to its mounting plate 104 and/or to fasten the mounting plate 104 to the door 201.

[0033] In the exemplary embodiments now presented, the same reference numerals are always used for identical or functionally identical components.

[0034] FIG. 2 shows a sectional view of the fastening element 1 in accordance with the first exemplary embodiment. An associated perspective view is shown in FIG. 3. For orientation, the door actuator 102 and the door 201 are shown purely schematically in FIG. 2.

[0035] The fastening element 1 comprises a base body 2 and a core 7. The base body 2 extends from a head 3 via a central area 4 to an unstable area 5 along its central axis 6.

[0036] The base body 2 has an external thread 11 on the central area 4 and on the unstable area 5 and is therefore designed as a screw.

[0037] The unstable area 5 is divided into four segments 9 by four slots 10. Each slot 10 extends parallel to the central axis 6 to the front end of the unstable area 5. Furthermore, the slot 10 extends in the radial direction from the lateral surface of the unstable area 5 to the core 7.

[0038] The core 7 extends substantially over the entire length of the base body 2, inside the base body 2 coaxial to the central axis 6. The core 7 protrudes into the unstable area 5 and thereby stabilizes the unstable area 5, so that the segments 9 cannot collapse radially inwards.

[0039] In the area of the head 3, the core 7 is firmly connected, in particular welded, to the base body 2 at a fastening area 8.

[0040] In the embodiment shown, the core 7 is formed entirely of a shape memory material, in particular a metallic wire.

[0041] FIGS. 4 and 5 schematically illustrate a thermal activation 30. As a result of this thermal activation 30, the core 7 shortens its length and as a result withdraws from the unstable region 5. The unstable area 5 can collapse inwards. As a result, in the unstable area 5, the external thread 11 releases from the associated internal thread in the door 201, allowing the door actuator 102 to fall off the door 201. This prevents the door actuator 102 and in particular the hydraulic fluid in the door actuator 102 from heating up too much. It is of course to be understood that the door actuator 102 is on a side of the door 201 facing away from the fire and the thermal activation 30 is caused by a fire on the opposite side of the door 201.

[0042] FIGS. 6 and 7 show the fastening element 1 in accordance with a second exemplary embodiment, in which the base body 1 is designed as an expansion dowel and the core 7 as an expanding mandrel. The core 7 is here again made entirely of the shape memory material.

[0043] FIG. 6 shows four different states A, B, C, D of the fastening element 1 in a sectional view. In state A, the core 7 has not yet been fully driven into the base body 2, whereby the unstable area 5 can collapse radially inwards. Again a plurality of segments 9 are provided here, which form the part of the expansion dowel to be expanded. Optional form-fitting lugs 20 can be used here for a form-fitting connection with the door 201.

[0044] After inserting the fastening element 1 according to state A, the core 7 is driven into the base body 2 according to state B and thus also extends into the unstable area 5, whereby the unstable area 5 is stabilized. This results in the unstable area 5 being clamped in the door 201 and at the same time in a form-fitting connection by means of the form-fitting lugs 20.

[0045] State C shows the thermal activation 30, in which the core 7 again withdraws from the unstable area 5, whereby the unstable area 5 can collapse and as a result the fastening element 7 can easily be released from the door 201. This in turn causes the door actuator 102 to fall off the door 201.

[0046] FIG. 7 shows the detail VII marked in FIG. 6. This detailed illustration shows that, in the area of the head 3 of the base body 2 in the fastening area 8, a press fit is formed between the core 7 and the base body 2. As soon as the core 7 has been driven into this fastening area 8, a force-fitting connection is created between the base body 2 and the core 7 in the fastening area 8, so that the core 7 is firmly connected to the base body 2 here.

[0047] It is to be understood that the fastening element 1 in accordance with both exemplary embodiments can also be used in other applications, in particular if an element to be fastened has to be released from its mounting surface in the event of fire.