DE20305818U1 - Emergency electrical manually operated switch has contact stages protected by sealing stage - Google Patents

Abstract

The emergency switch has a plunger actuator element [12] that is mounted on a carrier [18] that supports the contact elements [14,16] of the switching stages and are fixed using screws [22]. Within the housing is a sealing element [50] that is bonded to the contact elements and so prevents access to the fixing screws.

Description

WITTE, WELLER & PARTNER

Patent attorneys

Rotebühlstraße 121 D-70178 Stuttgart

Applicant:

Pilz GmbH & Co.

Felix-Wankel-Str. 2

73760 Ostfildern Germany

April 8, 2003 4035G102 - TD/rc

Emergency stop switch for safety-related switching off of electrical equipment

The present invention relates to an emergency stop switch for the safety-related switching off of electrical devices, with an actuating element, at least one contact element and a carrier element on which the at least one contact element and the actuating element are arranged.

Such an emergency stop switch is known, for example, from DE 31 42 925 Al.

Emergency stop switches in the sense of the present invention are used to be able to specifically switch off an electrical device, for example an electrical machine, an industrial production plant or an electrical supply device, in an emergency or dangerous situation. The emergency stop switches usually have a red actuating element, usually a push button, which is arranged against a yellow background, for example a yellow housing part. Due to the shape of the actuating element, which was at least widely used in the past, such emergency stop switches are often also referred to as mushroom buttons.

The emergency stop switches of this type have at least two electrical contacts that can be electrically separated from one another or connected to one another via a movable contact bridge. The contacts are usually connected to electrical connection terminals that enable electrical cables to be connected. The position of the contact bridge is influenced by the actuating element, so that the electrical contacts can be opened and/or closed via the actuating element.

Nowadays, the electrical contacts and the contact bridge are usually combined to form a contact element, which forms a modular component for a generic emergency stop switch. In many cases, the electrical contacts and the movable contact bridge are cast in a plastic body, which leaves the electrical connection terminals free. Such a contact element enables a simple and therefore cost-effective production of generic emergency stop switches, since the contact element (sometimes several contact elements) only

must be connected to the actuating element, which is often done via a suitable carrier element. The carrier element can, for example, be a plate with a through hole through which a plunger of the actuating element extends. The contact elements can then be arranged on the other side of the carrier plate in such a way that the plunger can influence the current position of the movable contact bridge. A simple way of attaching the contact element(s) to the carrier element is a screw connection, whereby the screw is already integrated in the plastic body of the contact element.

However, if the contact element is attached to the carrier element in this way, the emergency stop switch is not protected against deliberate or inadvertent manipulation. In the applicant's opinion, this poses a safety risk given the safety-relevant function of emergency stop switches.

Against this background, it is an object of the present invention to provide an emergency stop switch of the type mentioned above which offers a higher degree of safety.

This object is achieved by an emergency stop switch of the type mentioned above, in which at least one contact element is provided with a sealing part which is permanently connected to the carrier element.

By using such a sealing part, it is possible to prevent undetected manipulation of the emergency stop switch. This achieves a higher level of security, as the manufacturer can now control and ensure

can ensure that every emergency stop switch works according to its functional description and purpose. For example, there are two different basic types of contact elements, namely break contacts (closed in the idle state, open in the active state) and make contacts (open in the idle state, closed in the active state). Depending on the application, emergency stop switches can be equipped with different combinations of break and make contact elements. If a break contact element is replaced by a make contact element, which is certainly possible with the generic emergency stop switches, the emergency stop switch no longer works as intended, which represents a safety risk.

On the other hand, the use of a sealing part has the advantage that the previous production processes for the manufacture of emergency stop switches can basically be retained, in particular the use of modular, pre-assembled (standard) contact elements. Therefore, the increased level of safety is hardly or not at all reflected in the production costs of the new emergency stop switch.

Another advantage of a sealing part is that it does not fundamentally rule out the replacement of a contact element, provided that the sealing part can be broken open. In some applications, the use of a "deliberately manipulated" emergency stop switch makes more sense than, for example, not using an emergency stop switch at all or leaving the electrical equipment unusable for an unacceptably long period of time due to a lack of spare parts. The flexibility of emergency stop switches of this type, which can be advantageous in exceptional cases,

can (but does not have to) be retained. However, by breaking open the sealing part, the manipulation is evident, which leads to increased attention and responsibility and, as a result, to greater security.

In one embodiment of the invention, the sealing part and the carrier element are connected to one another via welding and/or adhesive points.

With welded and/or adhesive connections, sealing parts can be produced very cost-effectively and at the same time very reliably, so that the desired effect can be achieved in a particularly advantageous way. Welded points in particular are also particularly tamper-proof, which contributes to a further improvement in security.

In a further embodiment, the welding and/or bonding points include at least one pin-like connecting piece which is welded and/or bonded in a corresponding recess.

This design is a particularly effective way of connecting the sealing part to the carrier element. On the one hand, a tenon-like connection ensures a particularly firm hold. On the other hand, the adhesive and/or welded connection can be easily created, as the sealing part and the carrier element can easily be fixed in the desired mutual position. In addition, the design makes it easy to implement a way of breaking open the sealing part, which cannot be hidden or covered up.

In a further embodiment, the sealing part includes a clamp which engages around the at least one contact element.

Such a clamp can be used to provide very effective protection against manipulation in a simple and quick way. In addition, such a clamp can be fixed relatively easily, which simplifies the production process, and the clamp can be used as a retrofit part when standardized contact elements are used, which reduces material costs.

In a further embodiment, the at least one contact element is fastened to the carrier element via a further fastening means.

In other words, the sealing part is not the only fastening means with which the contact element is attached to the carrier element. This measure has the advantage that the sealing part can be designed relatively simply and thus inexpensively, since it does not (solely) have to ensure the necessary stability of the connection between the contact element and the carrier element.

In a further embodiment, the further fastening means is a screw with a screw head and the clamp has a bracket that covers the screw head.

This design is particularly advantageous when the (standard) contact elements described above are used, since the bracket provides additional protection against unwanted manipulation.

In a further embodiment, the at least one contact element has a body in which at least two electrical connection terminals and a movable contact bridge are integrated, and the sealing part is integrally connected to the body.

In other words, the sealing part in this embodiment is formed on the body of the contact element. In a particularly preferred embodiment, this is, for example, a pin and/or a flag that protrudes from the casting body of the contact element. This embodiment is particularly tamper-proof and also enables a reduction in the number of parts, which further simplifies the production process and thus reduces manufacturing costs.

In a further embodiment, the sealing part is colour-coded to contrast with the carrier element.

This design has the advantage that a break in the sealing part, i.e. the seal, can be detected particularly easily and quickly, which further prevents undetected manipulation.

In a further embodiment, the sealing part has a predetermined breaking point, which enables the contact element to be removed without causing damage.

This design is based on an aspect already mentioned above, namely that the removal of the contact element is not made impossible in principle. In individual cases, the flexibility gained can ensure safe operation of the

electrical equipment, whereby these situations represent and should represent the exception due to the actual function of the sealing part.

In a further embodiment, the actuating element is also secured by a sealing part, preferably the sealing part.

This design provides even better protection for the emergency stop switch against unwanted or undetected manipulation, as the sealing parts prevent any changes to the functional unit provided by the manufacturer.

In a further embodiment, the contact element has at least two electrically separated contact paths that can be activated simultaneously with the actuating element.

This design creates a redundancy that is particularly desirable in the safety-critical application area of emergency stop switches. In combination with the present invention, particularly cost-effective production is possible because the redundant channels are protected against manipulation by a common sealing part.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. They show:

Fig. 1 is a simplified exploded view of an emergency stop switch according to the invention in a side view,

Fig. 2 the emergency stop switch from Fig. 1 in a plan view from the direction of plane II-II, and

Fig. 3 shows another embodiment of the emergency stop switch according to the invention in a side exploded view.

In Fig. 1, an emergency stop switch according to the invention is designated in its entirety by the reference number 10.

The emergency stop switch 10 has a push button 12 as an actuating element, two contact elements 14, 16 and a carrier element 18. The contact element 14 is already attached to the carrier element 18 in the illustration in Fig. 1, and according to a preferred embodiment it is screwed to the carrier element 18 using a screw not shown in detail here. When assembling the emergency stop switch 10, the contact element 16 is placed on the carrier element in the direction of the arrow 20 and then screwed into a corresponding hole on the carrier element 18 using the schematically indicated screw 22.

Each of the two contact elements 14, 16 has two connection terminals 24, of which only one is shown in the illustration in Fig. 1.

one can be seen. The second connection terminal is located on the opposite side of the contact elements 14, 16.

The reference number 26 designates a slider which emerges from the housing body 28 of each of the contact elements 14, 16 on the side facing the carrier element 18. The slider 26 is connected within the housing body 28 of the contact elements 14, 16 to a movable contact bridge (not shown here) which, depending on the position, creates an electrical connection between the connection terminals 24 of a contact element.

The structure of such contact elements 14, 16 is sufficiently known in itself. The contact elements 14, 16 here are preferably those in which the fastening screw 22, the connection terminals 24, the slide 26 and the contacts (not shown here) and the contact bridge are cast in the housing body 28. The contact elements 14, 16 are therefore components that can be used in a modular manner.

In a particularly preferred embodiment, the emergency stop switch 10 has two contact elements 14, 16, each of which is designed as a normally closed contact element, i.e. whose connection terminals 24 are electrically connected to one another in the idle state via the contact bridge (not shown). However, the contact elements 14, 16 can also be two normally open contact elements or they can be contact elements of different types. Furthermore, the invention can also be used for emergency stop switches that have only one contact element or more than two contact elements.

The carrier element 18 has a base plate 30 on which the holes 32 for fastening the screws 22 of the contact elements 14, 16 are arranged. A tubular shaft 34 is connected to the base plate 30, to the free end of which the push button 12 is fastened in a manner not shown in detail here. The push button 12 has a plunger 36 which extends through the shaft 34 and a corresponding recess (not shown here) in the base plate 30. When the push button 12 is actuated in the direction of the arrow 38, the plunger is moved in the same direction within the shaft 34 and presses on the slides 26 of the contact elements 14, 16. The latter are thereby brought into their active state, i.e. with the normally closed contact elements preferably used here, the electrical connection between the respective connection terminals 24 is opened.

In a preferred embodiment, the plunger 36 is a screw that is pushed through the base plate 30 of the carrier element 18 from the direction of the contact elements 14, 16 and onto whose free end the (red) actuation button of the push button 12 is screwed. In this way, the push button 12 is connected to the carrier element 18. In addition, however, the push button 12 can also be connected to the carrier element 18 or the contact elements 14, 16 in another way. The implementation of the basic idea of the present invention is independent of the type of this fastening.

Furthermore, the push button 12 in conjunction with the carrier element 18 has a locking mechanism (not shown here) which locks the push button 12 in its active position after actuation in the direction of the arrow 38.

Unlocking is only possible by turning the push button 12. Details of this mechanical design are not shown here for the sake of simplicity, since they are of secondary importance within the scope of the present invention. In addition, such a locking of the push button 12 is known from generic emergency stop switches.

The emergency stop switch 10 also has a two-part housing, the front (upper) part 40 of which is yellow and accommodates the support element 18. The rear (lower) housing part 42 is black in the present embodiment and has a material point 44 that can easily be broken out to form a cable duct. The two housing parts 40, 42 are connected to one another in the present embodiment by screws 46. If the emergency stop switch 10 is installed in a control cabinet, the lower housing part 42 can also be omitted.

According to a preferred aspect of the present invention, the emergency stop switch 10 has a sealing part in the form of a clip 50, which is pushed onto the contact elements 14, 16 in the direction of the arrow 52 when the emergency stop switch 10 is mounted. According to a preferred embodiment, the clip 50 is color-coded to distinguish it from the carrier element 18 and preferably also from the contact elements 14, 16. In the illustration in Fig. 1, this is indicated by a cross-hatching of the clip 50.

The clamp 50 surrounds the two contact elements 14, 16 in a (square) ring shape, as is shown more clearly below in Fig. 2. Furthermore, the clamp 50 has

two brackets 54 which, when mounted, cover the screw heads 56 of the screws 22 of the contact elements 14, 16. At its free end, each bracket 54 has a pin 58 which engages in a corresponding recess on the screw head 56. As a result, the brackets 54 are automatically centered on the screw heads 56 when the clamp 50 is mounted and, furthermore, non-destructive bending of the brackets 54 to the side is prevented, which prevents access to the screws 22 even better.

The clamp 50 also has two pins or pins 60 at its end facing the carrier element 18, each of which is arranged on a thin projection 62 protruding laterally from the clamp 50. The arrangement of the projections 62 on the clamp 50 can be seen particularly clearly in Fig. 2.

The pins or pegs 60 are shown here with a thickening at their free end. This thickening can form a locking projection via which the pins 60 permanently lock into a corresponding recess 64 on the base plate 30.

In a particularly preferred embodiment, however, the pins 60 are welded in the recesses 64 of the carrier element 18, the thickening at the end of the pins 60 shown in Fig. 1 representing the connecting material liquefied during welding. In the particularly preferred embodiment, the clamp 50 is made of a plastic material so that the pins 60 can be permanently connected to the carrier element 18 by thermal welding.

In the illustration in Fig. 2, the two contact elements 14, 16 are shown from the side that is visible when the housing part 42 is open. As already mentioned, the bracket 50 surrounds the two contact elements 14, 16, and fits tightly, as shown here. For easier understanding, the screw heads 56 of the fastening screws 22 are also shown here in dotted lines. In fact, however, the screw heads are covered by the free ends of the brackets 54. Otherwise, the same reference numerals designate the same elements as in Fig. 1.

The connection terminals 24 of the contact elements 14, 16 are shown here with their screws 70 accessible from the rear. With the help of the screws 70, a cable (not shown here) can be clamped in the connection terminal 24. Furthermore, a recess 72 can be seen through which a part 74 connected to the slide 26 is visible in order to indicate the current position of the slide 26 and thus the opening or closing state of the contact elements 14, 16.

The reference number 76 designates a seal running around the carrier element 18, which seals the contact elements 14, 16 dust-tight in accordance with IP 65 when the housing parts 40, 42 are closed.

In the following description of a further embodiment, the same reference numerals designate the same elements as before.

In Fig. 3, a further embodiment of an emergency stop switch according to the invention is designated in its entirety by the reference numeral 80.

The emergency stop switch 80 again has a push button 12 as an actuating element. In contrast to the previous embodiment, however, there is only one contact element 82 here, which has redundant contact paths, i.e. two electrically separated contact paths 84, 86. Furthermore, the two contact bridges 88, 90 are indicated here, which run out at two separate slides 26.

In contrast to the previous embodiment, in the emergency stop switch 80 the sealing part is also integrated into the body 28 of the contact element 82. Specifically, these are two pins 92 which are inserted into corresponding recesses 64 on the base plate 30 of the carrier element 18. There, the pins 92 are in turn welded to the base plate 30 according to a preferred embodiment. Alternatively and/or additionally, however, an adhesive connection and/or a snap-in connection could also be used here. Furthermore, the contact element 82 can also be screwed to the base plate 30, as is indicated in Fig. 1 by the screw 22. Ultimately, the decisive factor is that the sealing part, i.e. the pins 92 integrally connected to the body 28, cannot be removed from the carrier element 18 and from the contact element 82 without causing damage.

In both illustrated embodiments of the invention, the push button 12, i.e. the actuating element, the carrier element 18 and the contact element(s) are arranged in such a way that

Unit connected in such a way that the push button 12 can only be removed after the sealing part has been destroyed. This is achieved here by the plunger 36 being pushed through the carrier element 18 from the inside of the housing part 40 and connected to the carrier element 18. The plunger 36 or the push button 12 can therefore only be released when the contact element or elements have been removed, which according to the invention is only possible after the sealing part has been destroyed or, in some embodiments, is not possible at all.

Furthermore, both embodiments shown here have in common that the pins 60, 92 are connected to the clamp 50 or the body 28 of the contact element 82 via a connection designed as a predetermined breaking point. As a result, the sealing part can break even with a relatively small amount of force, which particularly reliably excludes undetected manipulation.

Claims (11)

1. Emergency stop switch for the safety-related switching off of electrical devices, with an actuating element ( 12 ), at least one contact element ( 14 , 16 ; 82 ) and a carrier element ( 18 ) on which the at least one contact element ( 14 , 16 ; 82 ) and the actuating element ( 12 ) are arranged, characterized in that the at least one contact element ( 14 , 16 ; 82 ) is provided with a sealing part ( 50 , 60 ; 92 ) which is non-detachably connected to the carrier element ( 18 ). 2. Emergency stop switch according to claim 1, characterized in that the sealing part ( 50 , 60 ; 92 ) and the carrier element ( 18 ) are connected to one another via welding and/or adhesive points. 3. Emergency stop switch according to claim 2, characterized in that the welding and/or gluing points include at least one pin-like connecting piece ( 60 ; 92 ) which is welded and/or glued in a corresponding recess ( 64 ). 4. Emergency stop switch according to one of claims 1 to 3, characterized in that the sealing part includes a clamp ( 50 ) which engages around the at least one contact element ( 14 , 16 ). 5. Emergency stop switch according to claim 4, characterized in that the at least one contact element ( 14 , 16 ) is fastened to the carrier element ( 18 ) via a further fastening means ( 22 ). 6. Emergency stop switch according to claim 5, characterized in that the further fastening means ( 22 ) is a screw with a screw head ( 56 ) and that the clamp ( 50 ) has a bracket ( 54 ) which covers the screw head ( 56 ). 7. Emergency stop switch according to one of claims 1 to 6, characterized in that the at least one contact element ( 82 ) has a body ( 28 ) in which at least two electrical connection terminals ( 24 ) and a movable contact bridge ( 88 , 90 ) are integrated, and that the sealing part ( 92 ) is integrally connected to the body ( 28 ). 8. Emergency stop switch according to one of claims 1 to 7, characterized in that the sealing part ( 50 , 60 ; 92 ) is color-coded to contrast with the carrier element ( 18 ). 9. Emergency stop switch according to one of claims 1 to 8, characterized in that the sealing part ( 50 , 60 ) has a predetermined breaking point ( 62 ) which enables a destructive removal of the contact element ( 14 , 16 ). 10. Emergency stop switch according to one of claims 1 to 9, characterized in that the actuating element ( 12 ) is also secured against removal by a sealing part, preferably the sealing part ( 50 , 60 ; 92 ). 11. Emergency stop switch according to one of claims 1 to 8, characterized in that the contact element ( 82 ) has at least two electrically separated contact paths ( 84 , 86 ) which can be activated simultaneously with the aid of the actuating element ( 12 ).