EP3638868B1 - Safety contact strip - Google Patents

Description

The invention relates to a safety contact strip for a closing edge.

Safety contact strips are regularly used to protect people and material at crushing and shearing points, for example on gates, doors, machines and handling equipment.

One from the WO 2001/044611 A2 well-known safety contact strip is held on a mounting side in a carrier profile that can be placed on a closing edge. This known safety contact strip has two electrically conductive switching layers in a non-conductive, closed switching chamber within an outer shell of a profile, the switching chamber being kept free in a cross-section of spoke-like webs.

The profile, the switching chamber and the webs made of a first, non-conductive plastic, and the switching layers made of a second, electrically conductive plastic, each with at least one embedded metal conductor, are formed in one piece by a coextrudate.

The ones from the WO 2001/044611 A2 known safety contact strip switches very reliably when touched, however, due to the design, no statement can be made as to the direction from which a switching process-triggering force acting on the safety contact strip comes.

Such is with the from the U.S. 7,282,879 B2 known safety contact strip possible. This C-shaped or U-shaped profiled safety contact strip can, for example, encompass the closing edge of a gate swinging about an axis and can be determined by the formation of two electrical switching elements, each oriented in the direction of movement of the gate, from which direction a load causing a switching process he follows.

However, the construction of the safety contact strip as a whole, and in particular that of the switching elements, is very complex and complex. In addition, the determination of the direction of a load that triggers a switching process is only possible in the direction of movement of the door.

Against this background, the object of the invention is to provide an exactly switching safety contact strip that is structurally simple and mechanically stable.

This technical problem is solved by the subject matter of claim 1. The dependent claims represent advantageous developments.

An advantage of the safety contact strip according to the invention is that it is a one-piece coextrudate made from different plastics, both electrically insulating and electrically conductive, and electrical conductors.

The inner jacket is preferably used for contact and attachment directly to the closing edge, but optionally also for attachment by means of an attachment profile, and is therefore largely dimensionally stable. The outer cladding spaced from the inner cladding is on the other hand, deformable when hitting an obstacle.

With such a deformation of the outer casing relative to the essentially fixed inner casing, a switching signal is triggered by one or more switching chambers, if the deformation is sufficiently large, in which the switching layers in such a chamber touch one another.

In a manner known per se, electrical conductors are also embedded in the electrically conductive plastic of the two switching layers of a switching chamber.

In the case of the safety contact strip according to the invention, a plurality of switching chambers are also provided, preferably three. As a result of this measure, it is possible through the interconnection of the switching chambers to generate a common signal when an obstacle is encountered, or several which, if evaluated accordingly, also allow a statement to be made about the direction of the load on the safety contact strip.

This is particularly useful because according to the invention
Safety contact strip has a profile that encompasses the closing edge and is profiled in an L-shape, C-shape or U-shape for this purpose, for example to also encompass a post.

The response behavior of the switching chambers is essentially influenced by their suspension on the webs between the inner and outer shell. It has proven to be expedient if it is provided that a single web is provided between the outer shell and a switching chamber, the center plane of which is perpendicular to the inner surface of the outer shell.

The switching layers are then preferably oriented essentially perpendicularly to this central plane, so that the outer switching layer adjacent to the outer casing will largely follow the change in position of this web if the safety contact strip is deformed if this web is sufficiently stiff.

As a result of this measure, the position of the connection of the switching chamber to the outer shell will hardly change, while the deformation of the switching chamber necessary for a switching process then takes place essentially in relation to the inner shell.

For this reason, it is further provided that at least one further web is provided between the inner casing and a switching chamber and that the individual web between the outer casing and the switching chamber is rigid compared to the further web or webs between the switching chamber and the inner casing.

The switching chamber is preferably connected to the inner casing via two webs which run symmetrically to a central plane of the individual web in the non-deformed state. This avoids a preferred direction for switching the switching chamber.

In addition to the suspension of the switching chamber on the webs between the outer and inner shell, the geometry of the switching layers is important for the precise switching of the safety contact strip according to the invention.

It is provided that a first, outer switching layer is formed in a peg-like cross section, that the second, inner switching layer has a concave contact surface into which the first switching layer can dip, that the second Switching layer has the first switching layer bordering notches and that the center plane of the first switching layer, unloaded, is perpendicular to the second switching layer.

In this case, the first switching layer is preferably rounded off at its free end, so that a more linearly extending contact surface is formed.

The second switching layer, on the other hand, has a concave contact surface, through which the first switching layer, which is designed in the manner of a peg, is enclosed as it were when the switching chamber is deformed. Such framing is facilitated by the indentations, which to a certain extent also allow deformation of the second switching layer when the switching chamber is deformed.

The outer and inner shells are not only kept at a distance from one another by the interrupters held by webs, but also by intermediate walls. Thus, in a structural design, it is provided that the coextrudate of the second plastic forms intermediate walls between the outer and inner shell, the cross section of which narrows towards the inner shell. This measure also shifts the deformation of the safety contact strip as a whole towards the inner casing.

So that, viewed in cross-section, balanced switching behavior is also ensured in the area of the left-hand and right-hand ends of the safety contact strip enclosing a closing edge, it is further provided that the section facing the closing edge and closing the gap between the inner and outer casing the coextrudate of the second plastic is curved in an S-shape.

Such a configuration of the end sections of the safety contact strip according to the invention also makes it possible in a simple manner for the inner casing to protrude with a lug from the section closing the gap between the inner and outer casing. Such a flag also serves in particular to fix the inner casing to the closing edge, for example by means of screws. This is very easy if the lug is provided with a groove in the longitudinal extension of the safety contact strip, in which such screws can be attached.

In a further constructive embodiment of
Provision is made for the safety contact strip to be formed by the coextrudate of the first plastic material, two buffers protruding from the inner jacket and enclosing a switching chamber. In this context, particular consideration is given to the fact that in the case of a linear closing movement of the closing edge, a switching chamber is arranged centrally in front of the closing edge in the direction of the closing movement, which is framed by buffers of this type. If the safety contact strip hits an object when the closing edge closes at high speed, this front-side switching chamber is largely protected from damage.

For example, it can be provided that the first plastic has a lower Shore hardness than the second plastic, it being considered in particular that the first plastic has a Shore D hardness between 30 and 50 and that the second plastic has a Shore A hardness between 35 and 55.

Fig. 1:

in einem Querschnitt eine C-förmig profilierte Sicherheitskontaktleiste,

Fig. 2:

eine U-förmig profilierte Kontaktleiste und

Fig. 3:

eine vergrößerte Darstellung einer Schaltkammer.

The invention is explained in more detail with reference to the drawing, in which only two preferred exemplary embodiments are shown. In the drawing shows:

Figure 1:

a C-shaped profiled safety contact strip in a cross section,

Figure 2:

a U-shaped profiled contact strip and

Figure 3:

an enlarged view of a switching chamber.

The C-shaped profiled safety contact strip 1 according to figure 1 is intended for gripping around, for example, a round end post of a goal with a round cross-section. The elasticity of the plastics used allows for a sufficient widening of the opening of an inner casing 2. However, after the safety contact strip 1 has been applied to such a closing edge, the inner casing 2 should rest as precisely as possible on the closing edge.

The inner jacket 2 made of a first electrically insulating plastic is bordered by an outer jacket 3 made of a second, likewise electrically insulating plastic in a coaxial arrangement. The inner and outer shell 2.3 are a coextrudate.

Between the inner and the outer shell 2.3 three switching chambers 4-6 are provided in the embodiment.

Each of the switching chambers 4-6 is held here on three webs 7-9 in the space between the inner and outer shell 2.3. The single web 7 between the outer casing 3 and the switching chamber 4 is comparatively solid and stiff compared to the other two webs 8.9 between the switching chamber 4 and the inner casing 2.

The two webs 8 , 9 between the switching chamber 4 and the inner shell 2 are formed symmetrically to a central plane 10 through the web 7 .

The outer casing 3, the switching chambers 4-6 and the webs 7-9 are formed by a coextrudate of a second electrically non-conductive plastic.

The structure of the switching chambers 4-6 is similar and is shown on the basis of the enlarged representation of a switching chamber 15 in figure 3 explained further.

The switching chamber 15 held by the webs 16-18 between the inner casing 19 and the outer casing 20, as well as the webs 17, 18, are formed symmetrically to a central plane 21 through the web 16.

In the switching chamber 15, two opposing switching layers 22, 23 each made of an electrically conductive plastic are introduced as a coextrudate with the first and the second plastic. The outer switching layer 22 with respect to the enclosed closing edge is, in the cross section shown, formed like a peg with a rounded contact surface 24.

The center plane 21 through the pin 16 is perpendicular to the contact surfaces 24,25 of the first and second switching layers 22,23. The contact surface 25 of the second switching layer 23 is essentially concave, so that if the switching chamber 15 is deformed, the pin-like outer switching layer 24 can be surrounded by the second switching layer. In order for such an embracing movement to be facilitated are two the peg-like switching layer 24 enclosing notches 26, 27 are introduced into the switching layer 23.

In the two switching layers 22,23 two electrical conductors 28,29 are introduced.

The safety contact strip 1 is therefore a coextrudate made of two electrically non-conductive plastics, six strands of electrically conductive plastics in the three switching chambers 4-6 with six electrical conductors, which are also coextruded.

In the embodiment of the safety contact strip 1 according to figure 1 the center planes 10 of the switching chambers 4-6 intersect in the center of the circle spanned by the inner shell 2. Different orientations of the switching chambers 4-6 are possible without any problems.

In the embodiment of the safety contact strip 1 after figure 1 the arc of the outer casing 3 is also smaller than that of the inner casing 2. As a result, the inner casing 2 is in contact with the sections 33, 34 closing the space between the inner casing 2 and the outer casing 3 with two, for example, the fastening of the safety contact strip 1 a post serving flags 35,36, which are provided for easy application of, for example, screws with grooves 37,38 running along the safety contact strip 1.

Two intermediate walls 39 , 40 are extruded through the first plastic of the outer casing 3 and their cross section tapers towards the inner casing 2 .

Through the first plastic of the inner shell 2, two buffers 41,42 are also formed at a larger

Deformation of the safety contact strip in a linear movement along the plane of symmetry of the safety contact strip 1 and central plane 43 of the switching chamber 5 enclose and protect them.

The two switching layers of the switching chambers 4-5 can be connected in series in such a way that if any switching strip 4-5 is loaded and triggered, only a single switching signal is generated. However, it is then not possible to identify the direction from which a load is applied.

Alternatively, however, it is also possible to determine the direction from which the safety contact strip 1 is loaded. Regarding 1 If the switching chamber 4 responds, it will detect a load that occurs essentially from the left, the switching chamber 5 will detect a load from the front or from above, and the switching chamber 6 will detect a load from the right. Furthermore, if the front switching chamber 5 and one of the other switching chambers 4.5 respond, a load is applied obliquely from the front.

The safety contact strip 45 according to figure 2 is profiled in a U-shape in the cross section shown, but corresponds essentially to the safety contact strip 1 according to the technical structure figure 1 . Thus, like the safety contact strip 1 , the safety contact strip 45 is symmetrical to a central plane 46 which extends in the direction of a linear closing movement of a closing edge bordered by the safety contact strip 45 .

The safety contact strip 45 also has three switching chambers 47-49, which are each held by three webs 50-52. Due to the roundings 53,54 of the outer shell 55 are the center planes 56 of the webs 50 of the switching chambers 47, 49 perpendicular to the inner surface 57 of the outer casing 55.

The plastic material of the outer casing 55 also forms the sections 59, 60 which face the closing edge and close the gap between the inner and outer casing 58, 55 and are curved in an S-shape in this exemplary embodiment of a safety contact strip 45.

Partitions 61 are also formed by the second plastic of the outer jacket 55, in this exemplary embodiment there are four in total, of which a first section 62 adjoining the outer jacket 55 is perpendicular to the inner surface 57. A second section 63 of lesser material thickness adjoins the first section 62 at an angle of incidence, starting from the inner jacket 58 .

According to the first exemplary embodiment of a safety contact strip 1, two buffers 65, 66 made from the first plastic of the inner casing 58 also enclose the switching chamber 48.

For attachment to a closing edge, the lugs 67, 68 of the inner casing 58 protruding from the sections 59, 60, like the first exemplary embodiment, still have grooves 69, 70 running along the safety contact strip 45.

Claims (13)

1. A safety contact stripbeing profiled in an L-shaped, C-shaped, or U-shaped manner in the cross section, for at least partially encompassing a closing edge, whereinan inner jacket(2) facing the closing edge is formed by means of a coextrudate of a first electrically insulating plastic, wherein an outer jacket (3) is formed spaced apart from the inner jacket (2) by means of a coextrudate of a second electrically insulating plastic, wherein several switching chambers (4-6), which are held between the inner and outer jacket (2, 3) by at least one web (7-9) each, are formed by means of the outer jacket (3), wherein two switching layers (22, 23), which are spaced apart from one another, are formed in each switching chamber (15) by means of a coextrudate of a third electrically conductive plastic, and wherein an electrical conductor (28, 29) is in each case embedded as further coextrudates in the switching layers (22, 23) .
2. The safety contact strip according to claim 1, characterized in that a common signal is generated by means of the interconnection of the switching chambers (4-6) upon impinging on an obstacle, or that an evaluation of the individual signals of the switching chambers (4-6) allows a statement relating to the direction of the stress on the safety contact strip (1, 45) upon impinging on an obstacle.
3. The safety control strip according to one or several of the preceding claims, characterized in that the safety contact strip (1, 45) has a profile encompassing the closing edge.
4. The safety contact strip according to one or several of the preceding claims, characterized in that an individual web (16) is provided between the outer jacket (20) and a switching chamber (15), the central plane (21) of which is perpendicular to the inner surface of the outer jacket (20).
5. The safety contact strip according to one or several of the preceding claims, characterized in that at least one further web (17, 18) is provided between the inner jacket (19) and a switching chamber (15), and that the individual web (16) between the outer jacket (20) and the switching chamber (15) is formed to be stiff with respect to the further web or webs (17, 18) between the switching chamber (15) and the inner jacket (19).
6. The safety contact strip according to one or several of the preceding claims, characterized in that in a cross section, a first, outer switching layer (22) is formed in a cone-like manner, that the second, inner switching layer (23) has a concave contact surface (25), into which the first switching layer (22) can dip, that the second switching layer (23) has notches (26, 27) surrounding the first switching layer (22), and that the central plane (21) of the first switching layer (22) is perpendicular to the second switching layer (23).
7. The safety contact strip according to one or several of the preceding claims, characterized in that intermediate walls (39, 40), which taper in a cross section towards the inner jacket (2), are formed between the outer and the inner jacket (3, 2) by means of the coextrudate of the second plastic.
8. The safety contact strip according to one or several of the preceding claims, characterized in that the section (59, 60) facing the closing edge and closing the intermediate space between inner and outer jacket (58, 55) of the coextrudate of the second plastic runs in an S-shaped curved manner.
9. The safety contact strip according to one or several of the preceding claims, characterized in that the inner jacket (2) protrudes with a lug (35, 36) beyond the section (33, 34) closing the intermediate space between inner and outer jacket (2, 3).
10. The safety contact strip according to claim 9, characterized in that the lug (35, 36) is provided with a groove (37, 38) in the longitudinal extension of the safety contact strip (1).
11. The safety contact strip according to one or several of the preceding claims, characterized in that two buffers (41, 42) protruding beyond the inner jacket (2) and surrounding a switching chamber (5) are formed by means of the coextrudate of the first plastic.
12. The safety contact strip according to one or several of the preceding claims, characterized in that the first plastic has a lower Shore hardness than the second plastic.
13. The safety contact strip according to one or several of the preceding claims, characterized in that the first plastic has a Shore D hardness of between 30 and 50, and that the second plastic has a Shore A hardness of between 35 and 55.

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