EP2174330B1 - Microswitch - Google Patents

Abstract

The invention relates to a microswitch with at least two contact points, each with a moveable contact and a fixed contact, wherein the moveable contacts are arranged on a contact link, the contact link is capable of being moved by means of a plunger and can be moved over from a first switching position, in which contact points are open, into a second switching position, in which contact points are closed. During use of the microswitch, dirt may be deposited on the contacts, this having a disruptive effect on the microswitch, and in the worst case scenario, results in there no longer being a current flow in the closed position of the contact points. The intention is therefore to provide a microswitch with reliable self-cleaning. In this regard, the invention provides that the contact link is mounted in such a way that the contact link performs a rotary movement about an axis of rotation, which runs parallel to the longitudinal extent of said contact link, during closing and opening of the contacts, as a result of which a forced frictional movement transversely with respect to the longitudinal extent of the contact link takes place between the mutually opposite contacts of each contact point.

Description

The invention relates to a microswitch having at least two contact points, each having a movable contact and a fixed contact, wherein the movable contacts are arranged on a contact bridge, the contact bridge by means of a plunger movable and from a first switching position, in which the contact points are opened, in a second Switching position in which the contact points are closed, can be transferred.

Such microswitches have been in use for some time and are used in applications with low currents, such as control currents or fault currents, in the milliampere range. It is known that the contacts of these microswitches can become dirty in use, so that in the worst case in the closed position no current flow between the contacts takes place more.

It is therefore known to mount the contact bridge via springs on the switch plunger of the microswitch, so that when switching a relative movement between the movable contacts and the fixed contacts may occur, whereby contaminants are removed at the contacts.

The contact bridge is mounted on the spring floating in the plunger. As a result, the position of the contact bridge and the transmitted force during switching, d. H. when closing and opening the contact points, not clearly defined. The sequence of movement at the opposite contacts of the contact points when opening and closing is also not specified.

It is therefore the object of the present invention, an improved micro-switch, according to the preamble of claim 1, as disclosed in US-A-2 758 169 to provide, with a safe self-cleaning of the contacts when closing or when switching is achieved.

For this purpose, the invention provides as disclosed in claim 1, that the contact bridge is mounted so that the contact bridge performs a rotational movement about a parallel to its longitudinal axis of rotation when closing and opening the contacts, whereby between the opposing contacts each pad a positively driven Frictional movement takes place transversely to the longitudinal extent of the contact bridge.

Due to the mounting of the contact bridge, the rotational movement of the contact bridge during opening and closing is fixed. Therefore, the moving contacts at each

Switching performed on the same circular path, whereby the rubbing movement between the movable contacts and the fixed contacts always follows substantially the same path, transverse to the longitudinal extent of the contact bridge, and thus positively driven. In each switching operation thus takes place a substantially identical movement at the contact points. The fact that when switching a friction movement takes place transversely to the longitudinal extent of the contact bridge, the opposing contacts are also firmly past each other wiped, so that dirt is reliably rubbed or wiped from the contact points and in the closed position current flow is guaranteed.

In a preferred embodiment, it is provided that the plunger has an upper abutment against which the contact bridge in the closed position, and a lower abutment against which the contact bridge rests in the open position, wherein the upper abutment is arranged obliquely to the lower abutment , Thus, therefore, the contact bridge is transferred in a movement of the plunger from a position in which the contact bridge is arranged substantially perpendicular to the plunger in a position in which contact bridge is arranged obliquely to the plunger. Thereby, the rotational or tilting movement is generated, which is necessary so that the contacts rub against each other transversely to the longitudinal extent of the contact bridge. In addition, it can be ensured that with the plunger movement sufficient pressure for the self-cleaning of the contacts is generated.

A further variant provides that the contact bridge has at least one first, arranged transversely to the longitudinal extent of the contact bridge lever which is mounted in a receptacle in the plunger. The contact bridge is thus defined in a position defined in the receptacle of the plunger, there is a defined pivot point for the rotational movement of the contact bridge, by which the frictional movement is generated transversely to the longitudinal extent of the contact bridge to the contacts. By the distance of the fulcrum of the contact points can be adjusted, how large the rubbing motion between the contacts. The friction movement should not be too large, otherwise too strong friction and thus excessive wear on the contacts occurs.

Preferably, the first lever is arranged centrally between the two movable contacts on the contact bridge. This makes it possible to ensure that approximately equal forces act at both contact points.

A further preferred embodiment provides that the contact bridge has a further lever, which is arranged opposite to the first lever and in a guide guided in the ram. As a result, a centering of the contact bridge when closing and opening the contacts can be achieved.

In a favorable embodiment, it can be provided that the contact bridge is rotatably mounted about an axis extending transversely to the longitudinal axis of the ram and transversely to the longitudinal extent of the contact bridge. This allows the contact bridge perform a rocking motion, whereby vertical inaccuracies between the two contact points can be compensated. If the two fixed contacts are not arranged at the same height, this is compensated.

Conveniently, the contact bridge is also rotatably mounted about the ram longitudinal axis. This allows a rotational movement of the contact bridge, whereby a horizontal offset of the two fixed contacts can be compensated for each other.

A favorable embodiment provides that the upper abutment of the plunger has a rounded contact surface for the contact bridge. As a result, the rocking motion and the rotational movement are facilitated, are compensated by the slight misalignments of the two fixed contacts to each other.

In a variant, the microswitch may comprise at least one further contact bridge, which is constructed and supported substantially identically to the first contact bridge. In this way, a switch with double break and galvanic isolation can be realized.

It can be provided that each of the contact bridges is supported in ram longitudinal direction by means of a spring on the plunger, wherein one end of the spring is connected to the contact bridge and the other end of the spring is arranged in a receptacle in the plunger. Corresponds to the distance between the contact bridges on the plunger not exactly the distance of the fixed contact pairs in the housing to each other, these differences can be compensated by the resilient mounting.

A further expedient embodiment provides that a centering projection for the spring is arranged on each contact bridge. As a result, a simple attachment of the spring to the contact bridge is possible.

In an expedient embodiment, the fixed contacts may have a substantially V-shaped cross section and the movable contacts may have a substantially semicircular cross section. As a result, the friction movement in Supported longitudinal direction of the contact bridge when closing the contacts, there is an effective self-cleaning of the contacts instead.

Another embodiment provides that the microswitch comprises a housing and the plunger is guided in the housing, wherein the housing has a centering part which guides a centering element of the plunger. As a result, the plunger is held in the housing on the desired trajectory.

Fig. 1

Draufsicht auf einen geöffneten Mikroschalter mit zwei Kontaktbrücken in Offenstellung,

Fig. 2

Draufsicht auf einen geöffneten Mikroschalter mit zwei Kontaktbrücken in einer Zwischenstellung während des Schließvorgangs,

Fig. 3

Draufsicht auf einen geöffneten Mikroschalter mit zwei Kontaktbrücken in Schließstellung,

Fig. 4

Seitenansicht des Stößels des Mikroschalters mit zwei darin angeordneten Kontaktbrücken,

Fig. 5

Draufsicht auf eine teilweise Schnittdarstellung des Stößels mit zwei darin angeordneten Kontaktbrücken,

Fig. 6

Draufsicht auf eine Kontaktbrücke und

Fig. 7

Seitenansicht einer Kontaktbrücke.

In the following, embodiments of the invention will be explained in more detail with reference to a drawing. Show it:

Fig. 1

Top view of an open microswitch with two contact bridges in the open position,

Fig. 2

Top view of an open microswitch with two contact bridges in an intermediate position during the closing operation,

Fig. 3

Top view of an open microswitch with two contact bridges in the closed position,

Fig. 4

Side view of the plunger of the microswitch with two contact bridges arranged therein,

Fig. 5

Top view of a partial sectional view of the plunger with two contact bridges arranged therein,

Fig. 6

Top view on a contact bridge and

Fig. 7

Side view of a contact bridge.

Fig. 1 shows a plan view of a microswitch 1, wherein the housing cover of the microswitch 1 has been removed. The microswitch 1 comprises a housing 2, in which a plunger 3 is arranged. In the plunger 3 two contact bridges 4, 5 are mounted. On each of the contact bridges 4, 5 are two movable contacts 6.1, 6.2; 7.1, 7.2 arranged. The movable contacts 6.1, 6.2; 7.1, 7.2 each act with fixed contacts 8.1, 8.2; 9.1, 9.2 together, wherein the fixed contacts 8.1, 8.2; 9.1, 9.2 are arranged in the housing 2. The arranged on the contact bridges 4, 5 movable contacts 6.1, 6.2; 7.1, 7.2 thus form with the respective opposite fixed contacts 8.1, 8.2; 9.1, 9.2 two corresponding contact points 10.1, 10.2; 11.1, 11.2 off. The microswitch 1 thus comprises two double interrupts, whereby a galvanic isolation is realized and different circuits, or load and control currents, can be switched. The double interruption distributes the voltage applied to the switch to two fixed contacts. As a result, in contrast to the simple interruption with the same contact distance higher voltages and power can be applied. It is realized a higher electrical life and a higher contact reliability.

The plunger 3 is guided in the housing 2 in a guide 12 and can be transferred from a first position in which the contact points 10.1, 10.2, 11.1, 11.2 are opened, in a second position in which the contact points 10.1, 10.2, 11.1 , 11.2 are closed. In Fig. 1 the plunger 3 is shown in the first position with open contact points 10.1, 10.2, 11.1, 11.2. The housing 2 further has a centering part 13, which interacts with a arranged on the plunger 3 centering element 14 and the plunger 3 in the guide 12 centered. For this purpose, the centering part 13 and the centering element 14 have chamfered contact surfaces, which lie against one another in the open position of the contact points 10.1, 10.2, 11.1, 11.2 and position the plunger 3 centrally in the guide 12.

In Fig. 2 If a microswitch 1 is likewise shown without a cover, plunger 3 is in an intermediate position during the closing process. The actuation of the plunger 3 for transferring the contact points 10.1, 10.2, 11.1, 11.2 from the open position into a closed position can take place via a snap element, for example a bistable spring (not shown). But there are also other actuation mechanisms conceivable.

In the in Fig. 2 The position shown on the contact bridges 4, 5 arranged movable contacts 6.1, 6.2, 7.1, 7.2 already very close to the respective opposite fixed contacts 8.1, 8.2, 9.1, 9.2 arranged, but are not yet in the final position or the closed position. The plunger 3 has been moved away by the actuation of the snap element of the centering part 13 of the housing 2, so that the centering part 13 of the housing and the centering element 14 of the plunger 3 no longer touch. The contact bridges 4, 5 are still arranged substantially perpendicular to the plunger 3.

In Fig. 3 is the microswitch 1 in the closed position of the contact points 10.1, 10.2; 11.1, 11.2 shown. The plunger 3 was by the actuator (not shown) in moves the position in which the centering part 13 and the centering element 14 are farthest from each other. The force exerted by the actuator on the plunger 3 switching force is transmitted to the contact bridges 4, 5, so that the movable contacts 6.1, 6.2; 7.1, 7.2 with maximum switching force to the fixed contacts 8.1, 8.2; 9.1, 9.2 are pressed. The contact points 10.1, 10.2; 11.1, 11.2 are thus in the closed position. In the closed position, the contact bridges 4, 5 are arranged obliquely to the plunger 3.

In Fig. 4 is a side view of the plunger 3 with the therein mounted contact bridges 4, 5 shown. In the position shown, the contact bridges 4, 5 are in an open position of the contact points. In this open position of the contact points are the contact bridges 4, 5 each at a lower abutment 15, 16 of the plunger 3 at. Adjacent to each contact bridge 4, 5, an upper abutment 17, 18 is furthermore arranged in the plunger 3. Each of the upper abutments 17, 18 is arranged obliquely to the corresponding lower abutment 15, 16.

In the closed position of the contact points, each of the contact bridges 4, 5 abuts on the respective upper abutment 17, 18 and thus assumes an oblique position with respect to the open position. Opening planes spanned by the contact bridges 4, 5 in the open position therefore form an angle with closure levels spanned by the contact arms 4, 5 in the closed state.

Each of the contact bridges 4, 5 also has on one of its longitudinal sides a lever 19, 20 which is received in each case in a receptacle 21, 22 which is arranged in the plunger 3.

Further, at each of the contact bridges 4, 5 on the respective lever 19, 20 opposite longitudinal side, a further lever 23, 24 are arranged. The levers 23, 24 are each guided in a guide 25, 26 of the plunger 3, wherein the guides 25, 26 have a length which is greater than the width of the lever 23, 24, so that these levers 23, 24 during transfer of the contact bridges 4, 5 from the open position into the closed position in these guides 25, 26 can slide along. As a result, a centering of the contact bridges 4, 5 is achieved in the plunger 3.

In Fig. 5 is a partial sectional view of the plunger 3 is shown. Also in Fig. 5 the contact bridges 4, 5 are shown in the open position. In this case, the contact bridges 4, 5 are located on the respective lower abutments 15, 16. As shown, the upper run Abutment 17, 18 obliquely to the lower abutments 15, 16, so that the contact bridges 4, 5 perform a tilting movement when transferring from the open position to the closed position. The surface of the upper abutment 17, 18 is further rounded, so that a rotational movement of the contact bridges 4, 5 about the ram longitudinal axis and a rocking movement of the contact bridges 4, 5 about an axis transverse to the ram longitudinal axis and transverse to the longitudinal axis of the contact bridges 4, 5 is possible ,

Each of the contact bridges 4, 5 is mounted in the plunger 3 via a spring 27, 28. Each of the springs 27, 28 is fixed at one end on a centering projection 29, 30 of the contact bridges 4, 5. The respective other end of the springs 27, 28 is received in a recess 31, 32, which are arranged in the plunger 3. As a result, the springs 27, 28 are guided during the closing operation of the microswitch 1 in the respective recess 31, 32. By the springs 27, 28 can deviations in the distance of the contact bridges 4, 5 from each other and at a distance of the arranged in the housing 2 fixed contact pairs 8.1, 8.2; 9.1, 9.2 are balanced.

Fig. 6 shows a plan view of contact bridge 4. The other contact bridge 5 is identical to this contact bridge 4 constructed, the description therefore applies to both contact bridges.

On the upper side of the contact bridge 4, the centering projection 29 for the spring 27 is arranged centrally. At the lower longitudinal side 33 of the contact bridge 4, the first lever 19 is arranged. This lever 19 is preferably located centrally between the two movable contacts 6.1, 6.2. The transmitted by the plunger 3 when switching the microswitch 1 on the contact bridge 4 switching force is transmitted evenly through this arrangement of the lever 19 to both contact points 10.1, 10.2. As already described, the lever 19 is arranged in a receptacle 21 in the plunger 3. On the lever 19 opposite longitudinal side 34 of the contact bridge 4, the second lever 23 is arranged, which is received in a guide 25 in the plunger 3 and serves to center the contact bridge 4.

Fig. 7 shows a side view of the contact bridge 4. There are again the centering projection 29 and the upper lever 23 can be seen. On the underside of the contact bridge 4, the movable contacts 6.1, 6.2 are arranged.

The functional principle of the microswitch will now be explained with reference to the figures.

As already described, the microswitch 1 has an actuating element (not shown), preferably a bistable spring, by means of which the plunger 3 is transferred from a first position, the open position of the microswitch 1, into a second position, the closed position of the microswitch 1 can. In the open position of the microswitch 1, the in Fig. 1 is shown, are arranged on the contact bridges 4, 5 movable contacts 6.1, 6.2, 7.1, 7.2 separated from the arranged in the housing 2 fixed contacts 8.1, 8.2, 9.1, 9.2, so that there is an air gap between them. The contact points 10.1, 10.2, 11.1, 11.2 are therefore open. Each of the contact bridges 4, 5 abuts the respective lower abutment 15, 16 of the plunger 3. If the actuating element is actuated, a switching force is transmitted to the plunger 3 and the plunger 3 is moved in the guide 12, so that the microswitch 1 is transferred into the closed position. The closed position is in Fig. 3 shown. In the closed position of the microswitch 1, the contact points 10.1, 10.2, 11.1, 11.2 are closed, arranged on the contact bridges 4, 5 movable contacts 6.1, 6.2, 7.1, 7.2 are firmly against the opposite fixed contacts 8.1, 8.2, 9.1, 9.2. The contact bridges 4, 5 are now at the upper abutments 17, 18 of the plunger 3 at. Since the surface of the upper abutments 17, 18 is inclined relative to the surface of the lower abutments 15, 16, now also the contact bridges 4, 5 are inclined in the microswitch. 1

When transferring the contact bridges 4, 5 from the open position to the closed position, the contact bridges 4, 5 first together with the plunger 3 perform a translational movement until the movable contacts 6.1, 6.2; 7.1, 7.2 at the opposite fixed contacts 8.1, 8.2; 9.1, 9.2 abut. If this is the case, the contact bridges 4, 5 can no longer be moved translationally. However, the plunger 3 is not yet in its end position and is moved further translational. The contact bridges 4, 5 are now rotated, wherein the respective pivot point is the lower end of the respective first lever 19, 20 of the contact bridges 4, 5. The rotation thus takes place essentially about a rotation axis extending parallel to the longitudinal extent of the contact bridges 4, 5. By the length of this lever 19, 20 and thus by the distance of the fulcrum of the contact points 10.1, 10.2; 11.1, 11.2, the extent of the rotational movement can be determined. The contact bridges 4, 5 are rotated until they rest against the respective upper abutments 17, 18 of the plunger 3. By this rotational movement of the contact bridges 4, 5, a frictional movement is generated in the contact points 10.1, 10.2, 11.1, 11.2, which takes place transversely to the longitudinal extent of the contact bridges. Since each contact bridge 4, 5 via the respective first lever 19, 20 at a defined location, the respective receptacle 21, 22, is mounted in the plunger 3, the rotational movement of the contact bridges 4, 5 is fixed. Thus, the friction movement at the contact points 10.1, 10.2, 11.1, 11.2 is fixed or forced. By this positively driven friction movement possibly located in the contact points 10.1, 10.2, 11.1, 11.2 dirt is removed, possibly contaminated contacts are cleaned and it takes place in the closed position of the microswitch 1 safe flow of current.

In order to allow a centering of the contact bridges 4, 5 during this rotational movement, a second lever 23, 24 is provided on the contact bridges 4, 5, which is guided in a respective guide 25, 26 in the plunger 3 and in this guide 26 at the rotational movement of the contact bridges 4, 5 translationally moved.

The first levers 19, 20 of the contact bridges 4, 5 are preferably centered between the arranged on the contact bridges movable contacts 6.1, 6.2; 7.1, 7.2 arranged. Thus, it can be ensured that act at both contact points in approximately the same forces and thus an equally strong friction occurs. As already described, can be adjusted over the length of these levers 19, 20, how strong the frictional force acting on the contact points. Care must be taken to ensure that the frictional force is not too large, as excessive friction due to excessive wear on the movable contacts 6.1, 6.2; 7.1, 7.2 and the respective opposite fixed contacts 8.1, 8.2; 9.1, 9.2 occurs.

By the plunger 3, a moment is transferred to the contact bridges 4, 5 during the switching process, the friction force in the contact points 10.1, 10.2; 11.1, 11.2 generated.

In the manufacture of the microswitch 1, a small offset in the arrangement of the fixed contacts and the movable contacts may occur. For example, it is possible that the fixed contact pairs 8.1, 8.2; 9.1, 9.2 are slightly vertically offset. To compensate for this offset, the contact bridges 4, 5 are each rotatably mounted about an axis which extends transversely to the longitudinal direction of the ram and transversely to the longitudinal extent of the contact bridges 4, 5, whereby a rocking movement of the contact bridges 4, 5 is made possible. But it is also possible that the fixed contacts 8.1, 8.2; 9.1, 9.2 are offset in a horizontal plane. This offset is compensated by the fact that the contact bridges 4, 5 are rotatably mounted around the pushrod longitudinal direction. In order to facilitate these rocking or rotational movements of the contact bridges 4, 5, the upper abutments 17, 18 of the plunger 3 are provided with a rounded bearing surface.

Furthermore, it may be possible that the distance of the fixed contact pairs 8.1, 8.2 of the fixed contact pairs 9.1, 9.2 does not correspond to the distance of the contact bridges 4, 5 from each other. This can be compensated by the springs 27, 28.

As can be seen from the figures, the movable contacts 6.1, 6.2; 7.1, 7.2 a semi-circular cross section. The fixed contacts 8.1, 8.2; 9.1, 9.2 are preferably formed with a V-shaped cross section. By this form of the movable contacts and the fixed contacts, the friction movement is facilitated.

Claims (12)

1. Microswitch (1) comprising at least two contact points (10.1, 10.2; 11.1, 11.2) each with a movable contact (6.1, 6.2, 7.1, 7.2) and a fixed contact (8.1, 8.2, 9.1, 9.2), the movable contacts (6.1, 6.2, 7.1, 7.2) being arranged on a contact bridge (4, 5), it being possible to move the contact bridge (4, 5) by means of a ram (3) and it being possible to transfer the contact bridge from a first switching position, in which the contact points (10.1, 10.2; 11.1, 11.2) are open, into a second switching position, in which the contact points (10.1, 10.2; 11.1, 11.2) are closed, the contact bridge (4, 5) comprising at least one first lever (19, 20) arranged transversely to the longitudinal extension of the contact bridge (4, 5) and being mounted in such a way that when the contacts (6.1, 8.1; 6.2, 8.2; 7.1, 9.1; 7.2, 9.2) are being closed and opened the contact bridge (4, 5) executes a rotational movement about an axis of rotation running parallel to its longitudinal extension, characterised in that the at least one first lever (19, 20) of the contact bridge is mounted in a receiver (21, 22) in the ram (3), so the contact bridge (4, 5) is mounted at a defined point in the ram, the rotational movement of the contact bridge (4, 5) is fixed and therefore a frictional movement produced by the rotational movement at the mutually opposing contacts (6.1, 8.1; 6.2, 8.2; 7.1, 9.1; 7.2, 9.2) of each contact point (10.1, 10.2; 11.1, 11.2) transversely to the longitudinal extension of the contact bridge (4, 5) is forcibly actuated.
2. Microswitch (1) according to claim 1, characterised in that the ram (3) comprises at least one upper abutment (17, 18), on which the contact bridge (4, 5) rests in the closed position, and at least one lower abutment (15, 16), on which the contact bridge (4, 5) rests in the open position, the upper abutment (17, 18) being arranged obliquely to the lower abutment (15, 16).
3. Microswitch (1) according to claim 1 or 2, characterised in that the first lever (19, 20) is arranged centrally on the contact bridge (4, 5) between the two movable contacts (6.1, 6.2, 7.1, 7.2).
4. Microswitch (1) according to any one of claims 1 to 3, characterised in that the contact bridge (4, 5) comprises an additional lever (23, 24) which is arranged opposite the first lever (19, 20) and is guided in the ram (3) in a guide (25, 26).
5. Microswitch (1) according to any one of claims 1 to 4, characterised in that the contact bridge (4, 5) is mounted so as to be rotatable about an axis running transversely to the ram longitudinal axis and transversely to the longitudinal extension of the contact bridge (4, 5).
6. Microswitch (1) according to any one of claims 1 to 5, characterised in that the contact bridge (4, 5) is mounted so as to be rotatable about the ram longitudinal axis.
7. Microswitch (1) according to any one of claims 1 to 6, characterised in that the upper abutment (17, 18) of the ram (3) has a rounded supporting surface.
8. Microswitch (1) according to any one of claims 1 to 7, characterised in that the microswitch (1) comprises at least one further contact bridge (5; 4) which is substantially identically constructed and mounted to the first contact bridge (4; 5).
9. Microswitch (1) according to claim 8, characterised in that each of the contact bridges (4, 5) is supported on the ram (3) in the longitudinal direction thereof by means of a spring (27, 28), one end of the spring (27, 28) being connected to the contact bridge (4, 5) and the other end of the spring (27, 28) being arranged in a recess (31, 32) in the ram (3).
10. Microswitch (1) according to any one of claims 8 or 9, characterised in that a centring protrusion (29, 30) for the spring (27, 28) is arranged on each contact bridge (4, 5).
11. Microswitch (1) according to any one of claims 1 to 10, characterised in that the fixed contacts (8.1, 8.2, 9.1, 9.2) have a substantially V-shaped cross-section and the movable contacts (6.1, 6.2, 7.1, 7.2) have a substantially semi-circular cross-section.
12. Microswitch (1) according to any one of claims 1 to 11, characterised in that the microswitch (1) comprises a housing (2) and the ram (3) is guided in the housing (2), the housing (2) comprising a centring part (13) which guides a centering element (14) of the ram (3).

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