Safety contact strip

Abstract

A safety contact strip for a closing edge includes an inner shell facing the closing edge and being formed by a coextrudate of a first electrically insulating plastic. An outer shell spaced apart from the inner shell is formed by a coextrudate of a second electrically insulating plastic. Switching chambers respectively retained by at least one web between the inner and outer shells are formed with the outer shell. Two switching layers spaced apart from one another are formed in each switching chamber by a coextrudate of a third electrically conductive plastic. An electrical conductor is embedded in each of the switching layers as a further coextrudate.

Claims

1. A safety contact strip for a closing edge, the safety contact strip comprising: an L-shaped, C-shaped or U-shaped profile of the safety contact strip for at least partially encompassing the closing edge; an inner shell facing the closing edge, said inner shell being formed by a coextrudate of a first electrically insulating plastic; an outer shell spaced apart from said inner shell, said outer shell being formed by a coextrudate of a second electrically insulating plastic; webs disposed between said inner and outer shells; switching chambers formed with said outer shell, each of said switching chambers being retained by at least one of said webs; mutually spaced-apart switching layers formed by a coextrudate of a third electrically conducive plastic, each of said switching chambers receiving a respective two of said switching layers; and electrical conductors each being embedded as a further coextrudate in a respective one of said switching layers.

2. The safety contact strip according to claim 1, wherein said switching chambers are interconnected and upon striking an obstacle cause a common signal to be generated, or an evaluation of individual signals of said switching chambers allows a statement to be made about a direction of a stress of the safety contact strip when striking an obstacle.

3. The safety contact strip according to claim 1, wherein said webs include an individual web disposed between said outer shell and one of said switching chambers, said individual web having a central plane being perpendicular to an inner surface of said outer shell.

4. The safety contact strip according to claim 3, wherein: said webs include at least one further web disposed between said inner shell and one of said switching chambers; and said individual web disposed between said outer shell and said one switching chamber is stiffer than said at least one further web disposed between said one switching chamber and said inner shell.

5. The safety contact strip according to claim 1, wherein: said two switching layers include a first outer switching layer having a conical cross section and a second inner switching layer having a concave contact surface into which said first switching layer can dip; said second switching layer having notches enclosing said first switching layer; and said first switching layer having a central plane being perpendicular to said second switching layer in an unstressed state.

6. The safety contact strip according to claim 1, which further comprises intermediate walls formed by the coextrudate of the second plastic, said intermediate walls being disposed between said outer and inner shells, and said intermediate walls having a cross section tapering towards said inner shell.

7. The safety contact strip according to claim 1, which further comprises a curved S-shaped section of the coextrudate of the second plastic facing the closing edge and closing a space between said inner and outer shells.

8. The safety contact strip according to claim 7, wherein said inner shell has a lug protruding beyond said section closing said space between said inner and outer shells.

9. The safety contact strip according to claim 8, wherein said lug has a groove in a longitudinal extension of the safety contact strip.

10. The safety contact strip according to claim 1, which further comprises two buffers formed by the coextrudate of the first plastic, said two buffers protruding beyond said inner shell and enclosing one of said switching chambers.

11. The safety contact strip according to claim 1, wherein the first plastic has a smaller Shore hardness than the second plastic.

12. The safety contact strip according to claim 11, wherein the first plastic has a Shore D hardness of between 30 and 50 and the second plastic has a Shore A hardness of between 35 and 55.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will be described in more detail on the basis of the drawing, in which only two preferred exemplary embodiments are illustrated. In the drawing:

(2) FIG. 1: shows a safety contact strip, which is profiled in a C-shaped manner, in a cross section,

(3) FIG. 2: shows a contact strip, which is profiled in a U-shaped manner,

(4) FIG. 3: shows an enlarged illustration of a switching chamber, and

(5) FIG. 4: shows an illustration similar to FIG. 2, in which the safety contact strip has an L-shaped profile.

DESCRIPTION OF THE INVENTION

(6) The safety contact strip 1 according to FIG. 1, which is profiled in a C-shaped manner, is intended for example for engaging around a round end post of a gate comprising a round cross section. For this purpose, the elasticity of the used plastics allows a sufficient widening of the opening of an inner shell 2. After applying the safety contact strip 1 to such a closing edge, the inner shell 2, however, should abut as exactly as possible on the closing edge.

(7) The inner shell 2 of a first electrically insulating plastic is enclosed by an outer shell 3 of a second plastic, which is also electrically insulating, in a coaxial arrangement. The inner and the outer shell 2, 3 are a coextrudate.

(8) In the case of the exemplary embodiment, three switching chambers 4-6 are provided between the inner and the outer shell 2, 3.

(9) Each of the switching chambers 4-6 is retained here on three webs 7-9 in the space between the inner and the outer shell 2, 3. The individual web 7 between the outer shell 3 and the switching chamber 4 is formed to be comparatively massive and stiff as compared to the two other webs 8, 9 between the switching chamber 4 and the inner shell 2.

(10) 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.

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

(12) The setup of the switching chambers 4-6 is identical and will be further described in FIG. 3 on the basis of the enlarged illustration of a switching chamber 15.

(13) The switching chamber 15, which is retained between the inner shell 19 and the outer shell 20 by means of the webs 16-18, as well as the webs 17, 18 are formed symmetrically to a central plane 21 through the web 16.

(14) Two switching layers 22, 23 located opposite one another, each of an electrically conductive plastic, as coextrudate comprising the first and the second plastic are introduced in the switching chamber 15. In the illustrated cross section, the outer switching layer 22 with respect to the encompassed closing edge is formed conically comprising a rounded contact surface 24.

(15) The central plane 21 through the cone 16 is perpendicular to the contact surfaces 24, 25 of the first and second switching layer 22, 23. The contact surface 25 of the second switching layer 23 is formed essentially concave so that, in response to a deformation of the switching chamber 15, the outer switching layer 24, which is formed in a conical manner, can quasi be enclosed by the second switching layer. So that such an enclosing movement is facilitated, two notches 26, 27, which enclose the conical switching layer 24, are also introduced into the switching layer 23.

(16) Two electrical conductors 28, 29 are also introduced into the two switching layers 22, 23.

(17) The safety contact strip 1 is thus a coextrudate of two electrically non-conductive plastics, six strands of electrically conductive plastics in the three switching chambers 4-6, comprising six electrical conductors, which are likewise coextruded.

(18) In the case of the exemplary embodiment of the safety contact strip 1 according to FIG. 1, the central planes 10 of the switching chambers 4-6 intersect in the central point of the circle, which is spanned by the inner shell 2. Orientations of the switching chambers 4-6, which differ therefrom, are possible without any problems.

(19) In the case of the exemplary embodiment of the safety contact strip 1 according to FIG. 1, the curve of the outer shell 3 is furthermore dimensioned to be smaller than the curve of the inner shell 2. As a result, the inner shell 2 protrudes beyond sections 33, 34, which close the space between the inner shell 2 and the outer shell 3, with two lugs 35, 36, which serve, for example, for fastening the safety contact strip 1 to a post and which are provided with grooves 37, 38 running along the safety contact strip 1 for an easy attachment of, for example, screws.

(20) Two intermediate walls 39, 40, which taper towards the inner shell 2 in a cross section, are also extruded by means of the first plastic of the outer shell 3.

(21) By means of the first plastic of the inner shell 2, two buffers 41, 42 are further formed, which, in response to a larger deformation of the safety contact strip in response to a linear movement along the axis of symmetry of the safety contact strip 1 and central plane 43 of the switching chamber 5, enclose and protect the latter.

(22) The two switching layers of the switching chambers 4-5 can be connected in series in such a way that, in response to a stress and triggering of an arbitrary switching strip 4-5, only a single switching signal is generated. However, a detection of the direction of a stress is then not possible.

(23) In the alternative, however, a determination of the direction of a stress of the safety contact strip 1 is also possible. With reference to FIG. 1, the response from the switching chamber 4 will detect a stress, which occurs essentially from the left, the switching chamber 5 a stress from the front or from the top, respectively, and the switching chamber 6 a stress from the right. If the front switching chamber 5 and one of the other switching chambers 4, 5 also respond, a stress occurs diagonally from the front.

(24) The safety contact strip 45 according to FIG. 2 is profiled in a U-shaped manner and the safety contact strip 45 according to FIG. 4 is profiled in an L-shaped manner in the illustrated cross section, but the technical setup thereof essentially corresponds to the safety contact strip 1 according to FIG. 1. The safety contact strip 45, in the same way as the safety contact strip 1, is thus symmetrical to a central plane 46, which extends in the direction of a linear closing movement of a closing edge enclosed by the safety contact strip 45.

(25) The safety contact strip 45 also has three switching chambers 47-49, which are in each case retained by three webs 50-52. Due to the roundings 53, 54 of the outer shell 55, the central planes 56 of the webs 50 of the switching chambers 47, 49 are perpendicular to the inner surface 57 of the outer shell 55.

(26) The sections 59, 60, which face the closing edge and which close the space between inner and outer shell 58, 55, and which, in the case of this exemplary embodiment of a safety contact strip 45, are curved in an S-shaped manner, are also formed by means of the plastic material of the outer shell 55.

(27) Intermediate walls 61, in the case of this exemplary embodiment a total of four, of which a first section 62, which adjoins the outer shell 55, is perpendicular to the inner surface 57, are formed by means of the second plastic of the outer shell 55. Starting at the inner shell 58, a second section 63 of a smaller material thickness adjoins the first section 62 at an angle of attack.

(28) According to the first exemplary embodiment of a safety contact strip 1, two buffers 65, 66 of the first plastic of the inner shell 58 also enclose the switching chamber 48.

(29) For a fastening to a closing edge, the lugs 67, 68 of the inner shell 58, which protrude beyond the sections 59, 60, as in the first exemplary embodiment, also have grooves 69, 70, which run along the safety contact strip 45.