Closing-edge safety device with prechamber

Abstract

A closing edge safety device that triggers a safety response upon contact with an obstacle. The body of the safety device is an elastically deformable profile element that encloses a switch chamber containing a switching strip that carries an electrical current. A prechamber with a switching nub is placed at the leading edge of the safety device, in front of the switch chamber. When an external force is applied to the leading edge of the safety device, the switching nub transmits the force to the switch chamber, which also deforms, causing an interruption in the electrical current on the switching strip, thereby triggering the desired safety response of the closing edge safety device. The closing edge safety device provides improved response to large-area as well as small-area contact with an obstacle and is also suitable for use as a limit switch.

Claims

1. A closing edge safety device comprising: a profile element that is elastically deformable, the profile element having a first side that is mountable on equipment to be safeguarded, a second side that is a leading edge of the closing edge safety device and that is contact-sensitive, and a length that extends along an edge of the equipment; a switch chamber enclosed within the profile element, the switch chamber containing a switching strip made up of a plurality of contact elements, each contact element being in electrically conductive contact with an adjacent contact element, the switch chamber and the switching strip extending along a length of the profile element; and a switching nub that is spatially limited is enclosed in a prechamber that is formed within the profile element, between the second side and the switch chamber, the prechamber having a length that corresponds to a length of the switch chamber; wherein the switching nub is constructed so as to exert a spatially limited pressure that interrupts the electrically conductive contact of the contact elements in the switching strip when an external force is exerted on and deforms the profile element.

2. The closing edge safety device of claim 1, wherein the switching nub includes a plurality of switching nubs that are distributed over the length of the prechamber.

3. The closing edge safety device of claim 1, wherein the prechamber includes a plurality of prechambers provided adjacent to at least a partial circumference of the switch chamber; wherein at least one switching nub is provided in each of at least two prechambers.

4. The closing edge safety device of claim 1, wherein the switching nub is created by a material that is injected in a flowable state into the prechamber and solidifies in the prechamber to form the switching nub.

5. The closing edge safety device of claim 4, wherein the prechamber has a through-hole there where the switching nub is to be formed.

6. The closing edge safety device of claim 5, wherein the through-hole extends through the first side of the profile element and through the switch chamber to provide a pathway into the prechamber.

7. The closing edge safety device of claim 1, wherein the switching nub is constructed as a prefabricated component and is mounted on a guide element that extends through the prechamber.

8. The closing edge safety device of claim 7, wherein the guide element extends substantially over an entire length of the prechamber.

9. The closing edge safety device of claim 8, further comprising: end caps that close off two opposite ends of the prechamber; wherein the guide element is fixed to the end caps, thereby fixing a position of the guide element and the switching nubs within the prechamber when the end caps are in place.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements.

(2) FIG. 1 is a cross-sectional end view of a closing edge safety device according to the invention.

(3) FIG. 2 a partial cut-away side view of the closing edge safety device of FIG. 1, illustrating a switching nub and its relationship to the switch chamber that holds the switching strip.

(4) FIG. 3 is a cross-sectional end view of a second embodiment of the closing edge safety device and illustrates a switching nub that is created from a potting compound and filled into the prechamber via a bore through the leading edge of the profile element.

(5) FIG. 4 is a partial cut-away view showing a lengthwise cross-section through the embodiment shown in FIG. 3 and illustrating particularly a switching nub created in situ by injected potting compound.

(6) FIG. 5 is a cross-sectional end view through a third embodiment of the closing edge safety device according to the invention, illustrating a closing edge safety device according to the invention having three prechambers.

DETAILED DESCRIPTION OF THE INVENTION

(7) The present invention will now be described more fully in detail with reference to the accompanying drawings, in which the preferred embodiments of the invention are shown. This invention should not, however, be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be complete and will fully convey the scope of the invention to those skilled in the art.

(8) FIG. 1 illustrates a first embodiment of a closing edge safety device 1 according to the invention that comprises a body or housing that is a profile element 2 that encloses a switch chamber 7 that contains a switching strip 8A and a cable 11 that supplies the strip 8A with electrical current, and a prechamber 12 that contains a switching nub 14. The profile element 2 is made of an elastomeric material and has a first side or mounting side 3 and a second side or leading edge 6. The closing edge safety device 1 is conventionally fastened to the equipment or device that requires safeguarding, i.e., a safety stop, by fastening the mounting side 3 to a metal rail 4 that is then mounted along the surface of the equipment or device that requires safeguarding. Fasteners 5, such as bolts, are conventionally used to fasten the closing edge safety device 1 to the equipment. The leading edge 6 of the safety device 1 is the portion of the closing edge safety device 1 that is designed and mounted so as to be the first surface that makes an initial contact with an obstacle when the equipment is moving along its intended path. This leading edge 6 is contact-sensitive, i.e., touch- or pressure-sensitive.

(9) The switching strip 8A that is enclosed within the switch chamber 7 in the profile element 2 is made up of a plurality of switch elements 8, i.e., contact elements, whereby each switch element 8 is in electrically conductive contact with an adjacent contact element 8, so as to form a contact chain. An electric cable 11 that supplies the switching strip 8A with current is enclosed in a protective sheath 10 and is introduced through a wall of the profile element 2 into a deformation space 9 that is provided just below the switch chamber 7. The deformation space 9 allows the profile element 2 to deform when the closing edge safety device 1 makes contact with an obstacle. This deformation changes the shape of the switch chamber 7, thereby causing displacement of one or more of the switch contacts 8 and consequently, interrupting the contact between at least two adjacent contacts 8 in the switching strip 8A, which then triggers the switching operation of the closing edge safety device 1.

(10) FIG. 2 is a side view of the closing edge safety device 1 that is mounted on the rail 4 and extends substantially along the length of the surface of the equipment that requires the safeguard. The cut-away portion of the drawing shows in cross-section the switching strip 8A in the switch chamber 7 and the prechamber 12 between the leading edge 6 and the switch chamber 7. The illustration shows a switching nub 14 in the prechamber 12 and, in this embodiment, it is shown as a discrete element that is attached to the upper and lower walls of the prechamber 12. Unlike the switching strip 8A, which extends the entire length of the switch chamber 7, the switching nub 14 may be provided only at discrete intervals along of the length prechamber 12. Although only one switching nub 14 is shown in this illustration, it is understood that a plurality of switching nubs 14 may be provided, spaced apart along the length of the closing edge safety device 1 to ensure the desired high sensitivity response of the safety device 1.

(11) End caps 15 are used to seal off the ends of the prechamber 12, the switch chamber 7, and the deformation space 9, to prevent the ingress of objects, contamination, or moisture into the closing edge safety device 1.

(12) FIG. 3 illustrates a second embodiment of the closing edge safety device 1 according to the invention, showing a cross section of the end view similar to that of FIG. 1. In the embodiment of FIGS. 1 and 2, the switching nub 14 is a precisely formed contour piece, whereas the switching nub 14 in this second embodiment is created from a material that is referred to as a grouting or potting compound and that is initially in a flowable state. The potting compound is filled into the prechamber 12 while it is still in this flowable state and then solidifies in the prechamber 12 to form the switching nub 14. In the embodiment shown, an aperture or through-hole 16 on the second side 6 of the profile element 2 provides a path through which the flowable material is introduced into the prechamber 12. Ideally, the dosage of the material used is such that it also fills the through-hole 16, so that the solidified potting compound on the outer surface of the profile element 2 creates a dense and virtually uninterrupted surface.

(13) It may be desirable to avoid creating a break in the wall of the profile element 2 on the leading edge 6 of the device to inject the potting compound. Alternatively, then, the opening 16 to create a pathway into the prechamber 12 may be done from the mounting side 3. In this case, the opening 16 goes through the base region of the profile element 2 on the mounting side 3 and then through two opposite wall portions of the switch chamber 7; the flowable material is then injected via this pathway into the prechamber 12 to create the switching nub 14. This alternative pathway allows the leading edge 6 of the profile element 2 to remain intact, i.e., completely closed and uninterrupted; the break in the surface of the profile element on the mounting side 3 does not present a problem, because it is covered up when the safety device 1 is mounted on the rail 4 or on the equipment.

(14) FIG. 4 shows two partially cut-away cross-sectional views of the closing edge safety device 1 illustrated in FIG. 3, but to a smaller scale than shown in FIG. 3. As previously mentioned, the potting compound solidifies after it has been injected into the prechamber 12 and as it hardens, the volume shrinks. The material has good wall-adhesion and because of this, adheres well to the surfaces that form the upper and lower surfaces of the prechamber 12. As a result, the compound does not shrink evenly over the entire volume, but has greater shrinkage over the middle portion, forming a switching nub 14 that has an hourglass shape.

(15) FIG. 5 illustrates a third embodiment of the closing edge safety device 1 according to the invention, in which the prechamber 12 includes a plurality of such prechambers 12. In the embodiment shown, three prechambers 12 are provided in the area at the leading edge 6 and laterally on both sides of this leading edge. A middle prechamber 12A is directly aligned between the leading edge 6 and an upper portion of the switch chamber 7. Lateral prechambers 12B and 12C are provided on each side between the profile element 2 and an upper circumference of the switch chamber 7. All three prechambers 12 extend substantially the length of the closing edge safety device 1 and switching nubs 14 may be provided in all three prechambers. Overall, the prechambers 12A, B, and C and their switching nubs 14 in this embodiment surround more than half the circumference of the switch chamber 7. This increases the response sensitivity of the closing edge safety device 1 because the switching operation is triggered upon contact with an obstacle not only when the contact is a frontal contact at the leading edge 6, but also is also lateral to the leading edge 6.

(16) It is understood that the embodiments described herein are merely illustrative of the present invention. Variations in the construction of the closing edge safety device may be contemplated by one skilled in the art without limiting the intended scope of the invention herein disclosed and as defined by the following claims.