EP0618601A1 - Microswitch - Google Patents

Abstract

The invention relates to a microswitch having a housing (1) which has a base (2), connecting contacts (10, 11, 12) projecting out of the base, which connecting contacts (10, 11, 12) can be sealed from the housing by means of a potting compound (13) and are provided with receptacles for the connection of electrical cables. Since, in the case of normal microswitches, the dimensions of the switch are enlarged as a result of the necessary seals by additional parts required for sealing, the object of the invention is to make available a microswitch for use in different environmental conditions using as many identical components as possible, without in so doing changing the structural size. This object is achieved in that the base has a trough-shaped depression (4), which is surrounded by walls on at least three sides, for accommodating the potting compound, by the connecting contacts each having a separating line running within the depression and being capable of being cut to length on this separating line, in such a manner that the remaining residue of the connecting contacts also ends within the depression, the remaining residue of the connecting contacts likewise having receptacles for the connection of electrical cables. <IMAGE>

Description

The invention relates to a microswitch with a housing having a base, connection contacts protruding from the base, by means of a sealing compound, which are provided with receptacles for connecting electrical lines.

These microswitches are used in the industrial sector, in automotive engineering and in communications technology. Different environmental requirements are often placed on such microswitches. In DIN 40050, these requirements are classified into so-called IP protection types, which differentiate between protection against contact, foreign bodies and water. It has been shown that the seals required for a higher degree of protection either require a modified design, or that the external dimensions of the switch are enlarged by additional parts which are required for sealing. On the one hand, this leads to higher costs due to the production and assembly of additional parts; on the other hand, problems arise regarding the interchangeability of different types of microswitches, especially in compact products.

A microswitch, of the type mentioned at the outset, is known from G 9011926.6. In the case of a microswitch described there, connection contacts protrude from the housing on the lower connection side. To seal the connection contacts to which electrical lines are soldered, the connection side is placed in a trough-like part, as a result of which the cavity formed by the trough-like part and the connection side is filled with a casting compound. The additional trough-like part increases the size of the microswitch.

The invention has for its object to provide microswitches for use in different environmental conditions using as many of the same components as possible, without changing the size.

This object is achieved in that the base for receiving the potting compound has a trough-shaped depression surrounded by walls on at least three sides, that the connection contacts each have a dividing line running inside the depression and can be cut to length on this dividing line in such a way that the remaining one The rest of the connection contacts still end within the recess, the remaining rest of the connection contacts also having receptacles for connecting electrical lines.

The fact that a trough-shaped depression in the base is filled with a sealing compound, the outstanding contacts are sealed against the housing, the size remaining unchanged. This way you get a dustproof version of the switch. In order to hermetically seal the connection contacts against the ingress of water (compare, for example, degree of protection IP-67), the same connection contacts can be cut to length so that the rest of the connection contacts do not protrude beyond the edge of the trough-shaped recess. When cut to length, open receptacles for connecting electrical cables, into which, for example, strands can be soldered, are created at the same time. With the connected cables, the trough-shaped recess is now filled with a potting compound, whereby the connected rest of the connection contacts are completely sealed against the housing in accordance with the IP-67 requirement. Since none of the rest of the connection contacts protrude beyond the trough-shaped edge, the size of the microswitch remains unchanged. The structure of the tools can also be modular for this configuration of a microswitch, because the one in The rest of the connection contacts remaining in the base can be produced from the same connection contacts by means of a subsequent cut. The different bases can be manufactured by exchanging inserts in an injection mold, for example.

It is particularly advantageous if the receptacles in the remaining rest of the connection contacts are designed as openings and the dividing line of the connection contacts runs through the openings, so that after the connection contacts have been cut to length, open solder receptacles are formed, into which the lines can be inserted and soldered from above.

With such a design, it is much easier to insert the wires into the solder receptacles than to thread and solder them through soldering lugs.

Advantageously, the openings can be substantially triangular, so that after the connection contacts have been cut to length, solder receptacles are formed which are essentially V-shaped. This V-shape makes it even easier to insert the wires from above, as they are centered and clamped at the same time, which makes soldering easier.

A bell-shaped opening for connecting electrical lines can conveniently offer not only the simple insertion from above, the centering and clamping by a slight V-shape of the sides of the bell-shaped receptacle, but also a favorable shape for soldering that is adapted to the line cross section.

It is particularly advantageous if the dividing line of the connection contacts runs offset to the base next to the openings, so that a lateral recess is formed in addition to the openings and the soldering receptacle that is produced when the length is cut is compared to the rest of the connection contacts protrudes. This recess serves the purpose of being able to pass the connecting lines next to the contacts so that they do not protrude from the underside of the housing.

Conveniently, the receptacles in some of the connection contacts for connecting electrical lines can be arranged laterally offset with respect to the longitudinal center of the respective connection contacts. This has the advantage that all can be led out of the housing in a common plane.

It would be conceivable that the trough-shaped depression is only enclosed on three sides by walls, so that the electrical lines on the fourth side can thereby be laid out through the remaining opening, which is inexpensive and simple.

It is proposed to form the housing in two parts from a cover and the base, the cover being ultrasonically weldable to the base. Since the cover and the base are mostly made of plastic using the injection molding process, ultrasonic welding would be an option compared to gluing. Ultrasonic welding is easier to automate and is therefore faster and therefore cheaper than gluing. Due to the identical design, the bases can also be exchanged for the cover.

The cover of the housing can preferably have an opening which is aligned with a blind hole in the base. A switching tappet that can be operated from the outside can be guided in the opening and the blind hole. As a result, two guide bearings are formed which are particularly well suited to prevent the switching plunger from jamming and jamming when switching.

With low switching forces, it sometimes happens that the switch contacts weld at poor switching contact points within the switch and may therefore no longer be switchable with the operating elements. In the microswitch according to the invention, the problem could be solved by connecting the switching plunger to a positive opening lever which, after a predetermined plunger stroke, presses directly on a movable switching contact. This can be used to tear open any welds that may occur.

To seal the rubber bellows against the housing, a press ring can be used, which is welded or glued to the housing. In order to save this additional part, one could provide in the micro switch according to the innovation that an externally operable switching plunger protrudes from an opening of the housing, the opening on the outside of the housing being surrounded by an annular groove into which a rubber bellows with a lower circumferential one L-shaped edge provided with a radially outward-pointing lip can be used, the outer groove edge also being embossable radially inward by means of ultrasound and the embossed groove edge sealingly clamping the circumferential lip in the groove.

Fig. 1

einen Längsschnitt durch einen Mikroschalter gemäß der Erfindung,

Fig. 2

einen Querschnitt durch den erfindungsgemäßen Mikroschalter gemäß Schnittlinie II-II der Figur 1, die zur besseren Ansicht vergrößert dargestellt ist,

Fig. 3

einen Längsschnitt durch einen Mikroschalter mit einem modifizierten Sockel gemäß der Erfindung und

Fig. 4

einen Querschnitt durch den erfindungsgemäßen Mikroschalter gemäß Schnittlinie IV-IV der Figur 3, die zur besseren Ansicht vergrößert dargestellt ist.

These and other advantages that result from the microswitch according to the invention are explained in more detail with reference to several exemplary embodiments shown in the accompanying drawings. Show it:

Fig. 1

2 shows a longitudinal section through a microswitch according to the invention,

Fig. 2

2 shows a cross section through the microswitch according to the invention along section line II-II of FIG. 1, which is shown enlarged for a better view,

Fig. 3

a longitudinal section through a microswitch with a modified base according to the invention and

Fig. 4

a cross section through the microswitch according to the invention along section line IV-IV of Figure 3, which is shown enlarged for a better view.

Figure 1 describes a microswitch, which consists of a housing 1, which is composed of a base 2 and a cover 3.

A trough-shaped depression 4 is formed on the underside of the base 2 and is enclosed by walls on four sides. In the base 2 5 switching contacts 6, 7 and 8 are inserted on an upper switching side, which project vertically downwards on a lower connection side 9 as connection contacts 10, 11 and 12 from the trough-shaped recess 4 and are bent at an obtuse angle to the right. The trough-shaped recess 4 is filled with a casting compound 13, which seals the connection contacts 10, 11 and 12 against the base 2.

The switching contacts 7 and 8 are arranged one above the other on the switching side of the base 2 on the right side. A movable switch contact 14 is fastened to the switch contact 6 and is stamped from a sheet metal and bent like a clip. The outer end of the movable switch contact 14 is equipped on the lower and upper side with dome-shaped contact domes 15 and is in contact with switch contact 8 between the two switch contacts 7 and 8 in the upper position.

The lid 3 has an opening 16 on the top, in which a movable switching plunger 17 is guided vertically. At this switching plunger 17 is a horizontally attached Forced opening lever 18 mounted inside the housing 1, which is held in the uppermost position directly below the cover 3 by the resilient action of the movable switch contact 14. A vertical extension of the switching plunger 17 is also guided in a blind bore 19 in the base 2 aligned with the opening 16 of the cover 3. The switching plunger 17 acts on the movable switching contact 14.

The opening 16 in the lid 3 is surrounded on the top by an annular groove 20, in which a lower edge 21 of a rubber bellows 22 is inserted. The lower edge 21 is L-shaped, with this having a radially outwardly pointing lip 23. Material of the outer groove edge 24 is embossed inwards by means of ultrasound, the circumferential lip 23 being clamped in the groove 20 in a sealing manner.

The switching plunger 17 has a circumferential groove 26 in the upper region 25, which protrudes from the cover 3, into which the upper edge of the rubber bellows 27 is inserted. Since the width of the groove 26 is smaller than the wall thickness of the rubber bellows 22 at the upper edge 27, and the diameter of the circumferential groove 26 is larger than the diameter of the upper edge 27 of the rubber bellows 22, the upper edge of the rubber bellows 27 is by an interference fit tightly clamped.

In Figure 2, the sectional view is shown along a line II-II of Figure 1. The switching contacts 6, 7 and 8 have in the upper part two, protruding on both sides, rectangular lugs 28 which stand on the base 2 projections 29. Below the projections 29, the switching contacts 6, 7 and 8 are each hooked with two barbs 30 against an axial displacement in the vertical direction upward with the projections 29. The lid 3 has on its underside 31 an inner circumferential shoulder 32 which extends from above onto the protruding lugs 28 Switch contacts 6, 7 and 8 rests. The underside 31 of the cover 3 is ultrasonically welded to the base 2.

The connection contacts 10, 11 and 12 have within the trough-shaped recess 4 a bell-shaped opening 33 which is offset laterally to the longitudinal axis of the respective connection contacts. An imaginary separating line 34 runs through this opening 33 and divides the connecting contacts 10, 11 and 12 into the separable area 35 and the non-separable area 36.

2 shows the course of the dividing line 34 on the basis of the contact 11; the dividing line extends from the right edge 37 of the respective connection contact into a horizontal part 38 through the widest part of the opening 33 up to approximately the longitudinal axis of the respective switch contact. The further course of this dividing line 34 characterizes a lateral recess 39 to the left of the opening 33. This course extends from the longitudinal axis from the horizontal part 38 into a vertical part 40 upwards. This vertical part 40 extends tangentially approximately at the height of the center of the opening 33 into a 140 ° circular part 41 running counterclockwise, with an outer diameter which corresponds to approximately half the width of a switching contact. The end of the circular part 41 extends into a transition radius part 42 clockwise to the left edge 43 of the respective contact.

In the case of switching contact 10, the lateral recess 39 is arranged to the right of the associated opening 33, as cannot be seen from the drawing. The opening 33 of the switch contact 12 is arranged in the center.

Another exemplary embodiment of the microswitch is shown in FIGS. 3 and 4. Identical reference numerals are used for identical and similar components. Hereinafter only the differences from the above exemplary embodiment (FIGS. 1, 2) will be discussed.

A trough-shaped depression 104 is formed on the underside of a base 102 and is enclosed by walls on only three sides. Instead of the fourth wall (compare base 2 in FIG. 1), electrical lines 44, 45 and 46 are led horizontally out of a housing 101 through a remaining opening on the right side of base 102. Instead of the connection contacts 10, 11 and 12 (cf. FIG. 1), cut-off remnants of the connection contacts 110, 111 and 112 protrude from the trough-shaped depression 104, whereby these do not protrude beyond the edge of the depression 104. The strands 47, 48 and 49 of the electrical lines 44, 45 and 46 are soldered to the respective remnants of the connection contacts 110, 111 and 112. The trough-shaped depression 104 is also filled with a casting compound 13. Thus, on the one hand, the remnants of the connecting contacts 110, 111 and 112 are sealed off from the housing 101. On the other hand, the electrical lines 44, 45 and 46 soldered to the remnants of the connecting contacts 110, 111 and 112 are also sealed to the outside.

In FIG. 4, instead of the connecting contacts 10, 11 and 12, the remnants of the connecting contacts 110, 111 and 112 protrude from the base 102 into the trough-shaped recess 104. These have been cut to length at the dividing line 34 described in FIG. Instead of the bell-shaped opening 33, the connection contacts 110, 111 and 112 have a solder receptacle 50 which is open at the bottom and into which the respective electrical lines 44, 45 and 46 are soldered with their strands 47, 48 and 49.

In the lateral recess 39 produced by the dividing line 34 during cutting to length at the contact 111, the electrical line 44 soldered by the contact 110 is guided past the solder receptacle 50. The two lines are then at contact 112 44 and 46 passed to the side next to the correctly arranged soldering receptacle of the contact 112.

The operation and functioning of the microswitch will now be described.

When the switching plunger 17 is actuated in the housing 1, it presses down on the movable switching contact 14. As soon as the upper part of the movable switching contact 14 overcomes the switchover point, the outer end of the movable switching contact with the dome-shaped contact domes 15 snaps downward. The movable switch contact is now connected to switch contact 7. In the starting position, terminal contacts 10 and 12 are connected to one another; in the switched position, terminal contacts 10 and 11 are connected to one another.

When the switch is released, the system snaps back into the starting position. If the movable switch contact 14 is welded to the switch contact 8, the switching forces can be transmitted directly to the movable end of the switch contact 14 via the positive opening lever 18 after a predetermined tappet stroke and thus tear open the weld.

The modular structure of the microswitch enables the housing 1 of the microswitch to be designed according to different IP protection classes by slightly modifying the components.

The microswitch described in the first exemplary embodiment in FIGS. 1 and 2 has connection contacts 10, 11 and 12 which are only sealed against the housing 1. Only a few modifications are necessary to seal these connection contacts 10, 11 and 12 themselves in accordance with the IP 67 protection class requirement.

The same connection contacts 10, 11 and 12 only need to be cut to length at the dividing line 34 by means of a subsequent cut before installation in the base 2. The resulting residues of the connecting contacts 110, 111 and 112 then no longer protrude from the housing. The strands 44, 45 and 46 can now be inserted and soldered into the resulting solder receptacle 50. If the trough-like recess 4 is now filled with the potting compound 13, the solder joints within the recess are also sealed.

If the electrical lines 44, 45 and 46 are now to be placed not to the bottom but to the side of the housing 1, a modified base 102 is used which has a remaining opening instead of a wall. As a result, the electrical lines 44, 45 and 46 can be guided past the recesses 39 of the remnants of the connection contacts 110, 111 and 112 within the trough-like recess 104 and can be guided outwards through the remaining opening in the housing 1. The structure of the tools can also be modular for the modification of the base in that the inserts in the injection mold for the trough-like recess 4 and 104 are interchangeable.

Even a microswitch without protection, that is, according to protection type IP-00, which is not described in these exemplary embodiments, could be produced using the modularly designed tools. For this purpose, a housing 1 would be required, from which the connection contacts 10, 11 and 12 and the switching plunger 17 protrude without any sealing. The rubber bellows 22 would be dispensed with, so that the insert in the injection mold which would otherwise be necessary for the annular groove 20 can be removed. The connection contacts 10, 11 and 12 then no longer have to be sealed against the housing 1 by means of a casting compound 13, so that the insert in the injection molding tool for producing the trough-shaped recess 4 in the base 2 can also be removed here. These and other combinations regarding the degrees of protection are of course also conceivable.

Claims (11)

Microswitch with a housing having a base, connection contacts which can be sealed off from the base by means of a casting compound and which are provided with receptacles for connecting electrical lines, characterized in that
that the base (2; 102) for receiving the potting compound (13) has a trough-shaped depression (4; 104) surrounded on at least three sides by walls, that the connection contacts (10, 11 and 12) each have an inside the depression (4 ) running dividing line (34) and can be cut to length on this dividing line (34) in such a way that the remaining remainder of the connection contacts (110, 111, and 112) still ends within the recess (104), the remaining remainder of the connection contacts (110, 111 and 112) also has receptacles (50) for connecting electrical lines (44, 45 and 46). Microswitch according to Claim 1, characterized in that the receptacles (50) in the remainder of the connection contacts (110, 111 and 112) are designed as openings (33) and the dividing line (34) of the connection contacts (10, 11 and 12) the openings (33) run so that after the connection contacts (10, 11 and 12) have been cut to length there are open solder receptacles (50) into which the lines (44, 45 and 46) can be inserted and soldered from above. Microswitch according to Claim 2, characterized in that the openings (33) are essentially triangular, so that after the connection contacts have been cut to length (10, 11 and 12) solder receptacles (50) are formed, which are essentially V-shaped. Microswitch according to Claim 2 or 3, characterized in that the receptacle (50) for connecting electrical lines (44, 45 and 46) is designed as an essentially bell-shaped opening (33). Microswitch according to one of claims 2 to 4, characterized in that the dividing line (34) of the connection contacts (10, 11 and 12) runs offset next to the openings (33) to the base (2; 102), so that in addition to the openings ( 33) there is a lateral recess (39) and the solder receptacle (50) that is produced when the piece is cut to length protrudes from the rest of the connection contacts (110, 111 and 112). Microswitch according to one of Claims 1 to 5, characterized in that the receptacles (50) in some of the connection contacts (110, 111) for connecting electrical lines (44, 45 and 46) are arranged laterally offset with respect to the longitudinal center of the respective connection contacts . Microswitch according to one of Claims 1 to 6, characterized in that the trough-shaped recess (104) is enclosed by walls only on three sides. Microswitch according to one of Claims 1 to 7, characterized in that the housing (1; 101) consists of two parts a cover (3) and the base (2; 102) is formed, the cover (3) being able to be ultrasonically welded to the base (2; 102). Microswitch according to Claim 8, characterized in that the cover (3) of the housing (1; 101) has an opening (16) and the base (2; 102) has a blind bore (19) aligned with the opening (16), both through the blind bore and an externally operable switching plunger (17) are guided through the opening. Microswitch according to Claim 9, characterized in that the switching plunger (17) within the housing (1; 101) is connected to a positive opening lever (18) which, after a predetermined plunger stroke, presses directly on a movable switching contact (14). Microswitch according to one of Claims 1 to 10, characterized in that an externally operable switching plunger (17) protrudes from an opening (16) in the housing (1; 101), the opening (16) on the outside of the housing (1; 101) is surrounded by an annular groove (20) into which a rubber bellows (22) with a lower L-shaped edge (21) provided with a circumferential, radially outward-pointing lip (23) can be inserted, the outer groove also (24) can be embossed radially inwards by means of ultrasound and the embossed groove edge (24) clamps the circumferential lip (23) in the groove (20) in a sealing manner.

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