EP0698901A1 - Push button switch - Google Patents

Abstract

A pushbutton switch, in particular a mains switch, has contacts (4, 5) fixed to the housing and a contact bridge (8) connecting them and movable by means of a plunger (10). A jump switch (24, 25, 26) acts between the plunger (10) and a manually operated slide switch (22). The slide switch (22) can be locked by means of a locking device (27, 28) and alternately goes into the switch-on position and the switch-off position when pressed (E). In order to improve the switching behavior, a switching rocker (51) is additionally provided between the switching slide (22) and the plunger (10). At the beginning of the switch-on and switch-off processes, this force takes the plunger (10) in the switch-on direction or switch-off direction over a section of the contact stroke (H). After this section, the jumping behavior (24, 25, 26) brings the plunger (10) into the on position or the off position. <IMAGE>

Description

The invention relates to a push-button switch, in particular a power switch, with contacts fixed to the housing and at least one contact bridge which can be moved by means of a plunger, with a spring switching mechanism which is active between the plunger and a manually operable slide switch, and with a latching device for the slide switch, the slide switch when pressed alternately goes into the on position and the off position.

Such switches are used to disconnect electrical devices from consumer electronics, in particular television sets.

Such a push button switch is known from DE-AS 1 590 503. It has been shown that, despite the snap switch, such pushbutton switches can be manipulated in an undesirable manner by means of the slide switch in such a way that the contact pressure is influenced. If the slide switch is not actuated sufficiently quickly in such pushbutton switches, that is to say it is pushed very slowly and / or only partially, it can occur despite the snap-action switching mechanism that the contact pressure with which the contact bridge is fixed to the housing Contacts, goes to zero and this state can be maintained manually. This results in an increase in contact resistance and consequently in contact heating. This is associated with increased contact wear. In addition, the pushbutton switch may overheat, which not only reduces its functionality or service life, but also forms a source of fire risk.

A similar push button switch is described in DE-GM 91 01 126. Contact bouncing should be avoided with this. The problems mentioned also occur with this switch.

DE 31 50 046 A1 describes a slide switch in which, for example, welded contacts are to be torn open by a separating mechanism. This does not solve the problems mentioned at the beginning.

Another push-button snap switch is shown in DE 28 39 108 A1. In this case, the slide switch must be actuated in different directions to switch it on or off. In the switch according to DE 28 39 108 A1, arcing and contact bouncing should be avoided. For this purpose, a locking device is provided which blocks the plunger in its two end positions and which can be released by the movement of the slide switch. With this switch, too, undesired manipulations are possible, which cause the problems mentioned above.

Another push button switch is described in DE 20 31 364 A1. Even with this, the slide switch does not lock alternately in the switch-on position and in the switch-off position each time it is inserted. In order to achieve a snap behavior, a link connected with a snap spring is pushed over a cam.

From DE 36 44 437 C1 a pushbutton switch is known with a latching device which has a link and a latching finger engaging therein as latching parts. In order to counteract an overstressing of its actuating element in the actuating direction, one of the latching parts is held by a spring means so that it can escape.

DE 43 01 192 C1 describes a pushbutton switch that hardly leads to increased wear and functional reliability when operated manually. A pair of friction surfaces between the plunger and a part fixed to the housing leads to increased friction between the plunger and the part fixed to the housing shortly before the snap-action switch is snapped by moving the slide switch, as a result of which the snap-in of the plunger is delayed.

The springs of the spring switch mechanism pass through their tensioned state when the slide switch moves. If the plunger begins to move, it is braked by the friction surface pairing before it reaches a point of transition, while the necessary contact pressure is maintained. The point of transition is only reached when the springs are in a stronger state of tension than without the deliberate delay in the movement of the plunger in front of the point of transition; the plunger also passes through the transition point more quickly. As a result, the changeover point and thus the contact pressure can hardly be influenced by incorrect actuation of the slide switch. There is therefore no danger that the slide switch is manipulated and / or blocked in positions in which an increased contact resistance or arc leads to overheating and the associated increased wear or to a source of fire hazards. By means of a further friction surface pairing between the fly tappet and the part fixed to the housing, the movement of the spring tappet can be braked before the contact bridge strikes the contacts fixed to the housing, as a result of which bouncing of the contacts is suppressed.

The object of the invention is to improve the switching behavior, in particular with regard to the contact, in a pushbutton switch.

According to the invention the above object is achieved in a pushbutton switch of the type mentioned in that a switching rocker is provided between the slide switch and the plunger, that the switch rocker engages on the slide switch and on the other hand on the plunger and is mounted on the housing and that the switch rocker at the start of the switch-on process and of the switch-off process forcibly takes the plunger in the switch-on direction or switch-off direction over a section of the contact stroke, and after this section the jump switch brings the plunger into the switch-on position or switch-off position.

The result is that the speed at which the movable contacts strike the fixed contacts is reduced. As a result, short bounce times and short arcs occur, which reduces the wear on the contacts. Despite high switching power and high switching cycles, spatially small contacts can be used.

Another advantage is that when the switch is operated normally, an exact changeover point is maintained, since the jump ram caused by the spring switch mechanism occurs at the end of the section from a sliding movement of the jump ram. Compared to known switch designs, the transition point is therefore not affected by static friction. A user will not affect the transition point.

With regard to the switch-off process, there is the advantage that at most a small arc arises and that the contacts safely reach the open position even with greater adhesive forces.

Figur 1

eine Aufsicht eines Drucktastenschalters in Ausschaltstellung, teilweise geschnitten,

Figur 2

eine Seitenansicht des Drucktastenschalters in Ausschaltstellung, im Schnitt,

Figur 3

eine Figur 1 entsprechende Darstellung des Drucktastenschalters in Einschaltstellung

und

Figur 4

eine Figur 2 entsprechende Ansicht des Druckttastenschalters in Einschaltstellung;
wobei die Figuren 1 bis 4 den schon in der älteren Patentanmeldung P 43 01 192.6 beschriebenen Drucktastenschalter zeigen und

Figur 5 und Figur 6

Aufsichten eines erfindungsgemäßen Drucktastenschalters mit Schaltschwinge beim Einschaltvorgang (Übergang von der Ausschaltstellung in die Einschaltstellung) und

Figur 7 und Figur 8

Aufsichten des erfindungsgemäßen Drucktastenschalters mit Schaltschwinge beim Ausschaltvorgang (Übergang von der Einschaltstellung in die Ausschaltstellung).

Further advantageous refinements of the invention result from the subclaims and the following description of an exemplary embodiment. The drawing shows:

Figure 1

a top view of a push button switch in the off position, partially cut,

Figure 2

a side view of the push button switch in the off position, in section,

Figure 3

a representation corresponding to Figure 1 of the push button switch in the on position

and

Figure 4

a Figure 2 corresponding view of the push button switch in the on position;
Figures 1 to 4 show the push button switch already described in the earlier patent application P 43 01 192.6 and

Figure 5 and Figure 6

Top views of a push button switch according to the invention with rocker arm during the switch-on process (transition from the switch-off position to the switch-on position) and

Figure 7 and Figure 8

Top views of the push button switch according to the invention with switching rocker during the switch-off process (transition from the switch-on position to the switch-off position).

A housing (1) of the push button switch has a base part (2) and a cover part (3). Two pairs of contacts (4.5 and 6.7) are attached to the bottom part (2). A contact bridge (8.9) is assigned to each contact pair (4.5 or 6.7). It is a two-pole switch.

A plunger (10) is slidably mounted on the base part (2) in the direction of the longitudinal axis (L). The plunger (10) has two chambers into which compression springs (11, 12) are inserted. These are supported on the one hand on a pin (13) of the chamber and on the other hand on the contact bridge (8 or 9). For this purpose, the contact bridge (8 or 9) has an indentation (14). The contact bridges (8, 9) protrude on both sides of the longitudinal axis (L) through openings (15) in the plunger (10) in which they have play.

A spring-elastic tongue (16) is formed on the plunger (10) and interacts with a hump (17) formed on the base part (2) in the manner described in more detail below. A first slope (18) of the hump (17) and a first slope (19) of the tongue (16) form a first pair of friction surfaces. A second slope (20) of the hump (17) and a second slope (21) of the tongue (16) form a second pair of friction surfaces (cf. FIG. 2, FIG. 4).

On the bottom part (2) a slide switch (22) is slidably mounted in the direction of the longitudinal axis (L), which projects in the direction of the longitudinal axis (L) beyond the housing (1) and outside the housing (1) a receiving pin (23) for forms a push button, not shown.

An arm (24) is formed on both sides of the longitudinal axis (L) on the slide switch (22). A compression spring (26) is arranged between each of the arms (24) and an extension (25) of the plunger (10). As a result, a snap switch is formed between the plunger (10) and the slide switch (22).

An approximately heart-shaped link (27) is formed on the slide switch (22) and is used to guide a locking lever (28). The locking lever (28) engages with a hexagonal profile (29) in the link (27). On the outside of the base part (2) there is a notch (30) into which a rounded portion (31) of the locking lever (28) engages.

The locking lever (28) also has an extension (32) outside the base part (2) which engages in a compression spring (33) which is also the return spring (33) for the slide switch (22). The return spring (33) lies in a chamber (34) of the slide switch (22) and is held in this by a projection (35).

The locking lever (28) has a bevel (36) on its side facing the return spring (33), so that the locking lever (28) tends to be mounted in the notch (30) with its pin (29) in a preferred direction pivot - in Fig. 1, 3 to the right -.

The push button switch described is easy to assemble by machine. For this purpose, all parts can be inserted from the same side (in FIG. 1 perpendicular to the plane of the drawing, in FIG. 2 from the right into the base part 2). The springs described can also be used mechanically. In the same direction, the cover part (3) is placed, which is shown in Figures 1, 3 only to the left of the longitudinal axis (L). Pins (38) and pins (39) formed on ribs (37) engage in bores (40) of the base part (2). A lower peripheral edge (41) of the base part (2) forms a support for a circuit board (not shown in more detail) which the contacts (4 to 7) can be connected. The contacts (4 to 7) are protected inside the edge (41) so that no particles can reach the contacts (4 to 7) from the outside.

The function of the described push button switch is approximately as follows:

In the switch-off position shown in FIGS. 1, 2, the slide switch (22) is pressed against a stop (42) by means of the return spring (33). The compression springs (26) are relatively relaxed and the plunger (10) is pressed by them against a stop (43). The compression springs (11, 12) press the contact bridges (8, 9) against the edges (44) of the openings (15). The contact bridges (8,9) are spaced from the contacts (4,5 or 6,7).

If the switch is to be switched, then the slide switch (22) is moved in the push-in direction (E). The link (27) moves with a guide section (47) relative to the pin (29) of the locking lever (28). When moving the slide switch (22), the compression springs (26) are tensioned, which go over their dead center. Until then, the plunger (10) remains motionless. After the dead center has been exceeded, the compression springs (26) act in the opposite direction, so that the plunger (10) is now accelerated against the direction of insertion (E). After a movement that is initially free in the stroke (a) (cf. FIG. 2), the second slope (21) of the tongue (16) meets the second slope (20) of the hump (17), these slopes now abutting one another as friction surfaces. These friction surfaces now slide against one another while pivoting the tongue (16), as a result of which the movement of the plunger (10) is braked, so that the contact bridges (8, 9) then braked hit the contacts (4.5 or 6.7). Contact bouncing is thereby avoided or at least reduced. After the contact bridges (8.9) hit the contacts (4.5 or 6.7), the plunger (10) moves so far that the edges (44) of the contact bridges (8.9) remove. The contact pressure is now guaranteed by the compression springs (11 or 12).

When the slide switch (22) is released, the pin (29) of the locking lever (28) goes into a locking receptacle (45) of the link (27). The push button switch is now in the switch-on position shown in FIGS. 3 and 4.

If the slide switch (22) or its push button is pulled forcibly in the pulling direction (Z) in a manner not provided for the actuation of the switch, then the locking device, namely the link (27) or the locking lever (28) in push button switches according to the prior art. , damaged. If the pushbutton switch on the slide switch (22) is pulled in the direction (Z), the link (27) takes the locking lever (28) in the direction of pull (Z). This is possible because the locking lever (28) is supported in this direction (Z) not on the housing (1), but on the slide switch (22) via the compression spring (33). The slide switch (22) is therefore free to move in the direction of pull (Z). If the slide switch (22) is moved to such an extent that it hits the stop (42), then the plunger (10) snaps in the manner described in more detail below by means of the compression springs (26) of the spring switch from the switched-on position to the OFF position.

To regularly switch the pushbutton switch from the switch-on position to the switch-off position, the slide switch (22) is actuated in the push-in direction (E). The slide (27) moves relative to the pin (29) of the locking lever (28), so that the pin (29) the locking receptacle (45) under the action of the compression spring (33) pressing on the slope (36) in the direction of Arrow (A) leaves (see. Fig. 3). After a short stroke (b), which only has to be large enough for the pin (29) of the locking lever (28) to go out of the locking receptacle (45), the slide switch (22) meets an edge (46) of the base part (2 ). Until then, the plunger (10) is stationary and held by the compression springs (26) so that its compression springs (11, 12) have the necessary contact pressure between the contact bridges (8.9) and the contacts (4.5 and 6.7 ) maintained.

The slide switch (22) is then released or slowly manipulated in an undesirable manner. In both cases it moves under the action of the return spring (33) in direction (Z). The compression springs (26) stretch to their dead center. Shortly before reaching the dead center, the plunger (10) begins to move in the direction (E). Because of the free stroke (c) existing between the edges (44) and the contact bridges (8,9), the contact bridges (8,9) are not yet acted upon by the edges (44). Between the first slope (18) of the hump (17) and the first slope (19) of the tongue (16) there is a free stroke (d) in the switch-on position, which is smaller than the free stroke (c). The bevels (18, 19) acting as friction surfaces therefore meet one another, before the edges (44) act on the contact bridges (8,9). The friction surface pairing of the bevels (18, 19) means that the snap-in of the plunger (10) or the contact bridges (8, 9) is delayed. The edges (44) of the plunger (10) only meet when the friction surfaces formed by the bevels (18, 19) have slid against one another, the spring-loaded tongue (16) pivoting and the tension state of the compression springs (26) increasing the contact bridges (8,9), the bevels (18,19) having separated from one another. The contact bridges (8.9) suddenly snap off the contacts (4.5 or 6.7). The push button switch then comes into the switch-off position shown in FIGS. 1 and 2.

Before the point of transition is reached, at which the contact bridges (8,9) suddenly detach from the contacts (4,5 or 6,7), the user can manipulate the slide switch (22) without, however, the contact bridges can bring a state in which they lie on the contacts (4.5 or 6.7) with insufficient contact pressure. If the slide switch is manipulated, for example, into an intermediate position in which the bevels (18, 19) already lie against one another and the compression springs (26) are in the area of their dead center, this does not result in a dangerous increase in the contact resistance between the contact bridges (8, 9). and the contacts (4.5 or 6.7) and also not the risk of manipulable arcing.

The bevel (19) parallel to the bevel (18) and the bevel (21) parallel to the bevel (20) have different angles of inclination which are adapted to the described modes of operation. As a rule, the bevels (18, 19) are steeper than the bevels (20, 21) because the bevels (18, 19) serve to increase the effect of the springs (26) as energy stores and the bevels (20, 21) are only braking should work.

It is favorable that the tongue (16) is relieved both in the switched-on position and in the switched-off position - that is, for the longest time - and is only deflected during the switching. It is also possible to design the spring-loaded tongue (16) on the base part (2) and to provide the hump (17) on the plunger (10).

However, the pair of friction surfaces (18, 19; 20, 21) can also be designed so that they are not at an angle to the direction of insertion (E), but parallel to it. A resilient element is not necessary in this case. The surfaces leading to increased friction can then be designed with a corresponding surface structure.

It can also be provided that the locking lever (28) is mounted in the base part (2). It is then supported in this by means of an additional spring, which enables it to be taken along when moving in the direction of pull (Z). It is also in reverse of the conditions described possible to mount the locking lever (28) on the slide switch (22) and then to provide the link (27) on the base part (2). If the locking lever (28) does not leave the movement of the slide switch (22) free when pulling in the pulling direction (Z), the link (27) can instead be mounted such that it follows the movement of the locking lever (28) during such a movement.

Another switching contact (48) is shown in FIG. This is used, for example, to display the respective switching state of the push button switch.

With regard to FIGS. 5 to 8, reference is made to the above statements. The new parts and functions are described below.

A recess (49) is provided on one arm (24) of the slide switch (22). A first arm (50) of a rocker arm (51) engages in this. A second leg (52) of the rocker arm (51) has a circular opening (53) into which a pin (54) engages, which is formed on the extension (25) of the plunger (10).

Between the legs (50, 52) a bearing recess (55) is formed on the rocker arm (51), into which a housing-fixed bolt (56) projects with play. The bolt (56) is designed on the cover part (3) (see FIG. 2).

Starting from the switch-off position shown in FIG. 5, the switch-on process proceeds approximately as follows:

If the slide switch (22) is actuated in the push-in direction (E), then its arm (24) takes the rocker arm (51) with it on its leg (50). This rotates around the bolt (56) and forcibly takes the plunger (10) against the push-in direction (E) for a portion of the contact stroke (H) (see FIG. 5). By dimensioning the lengths (L1 or L2) of the legs (50 or 52), an intermediate state is then achieved (cf. FIG. 6), in which between the contact bridge (8) and the contacts (4, 5) and accordingly a residual stroke (H1) is also free between the other contact bridge (9) and the contacts (6, 7) assigned to it. In this intermediate state, the contacts of the contact bridges (8, 9) and the contacts (4, 5 and 6, 7) are still so far apart that no arcing can occur. In this intermediate state, play (S1) is free in the bearing recess (55), so that under the action of the now tensioned compression springs (26) (only one compression spring is shown in FIGS. 5 to 8), the plunger (10) counteracts the switching slide (22) which locks in the manner described snaps into the switch-on position shown in FIG. 7, in which the contacts are closed. The free stroke (c) already described occurs between the contact bridges (8, 9) and the edges (44). This process cannot be influenced by the user. Since the residual stroke (H1) is defined and is shorter than the contact stroke (H), the impact speed of the contacts is that of the contact bridges (8, 9) on the contacts (4, 5 or 6, 7) compared to the embodiment according to the figures 1 to 4 significantly reduced.

The contact bounce times are therefore comparatively short, so that at most short arcs and thus only a small amount of wear on the contact materials occur. The residual stroke (H1) ensures an exact point of change that the user cannot influence.

If, starting from the switch-on position shown in FIG. 7, the switch-off process is triggered, for which the user actuates the slide switch (22) in the push-in direction (E), the switch slide (22) becomes counter to the push-in direction after releasing the locking action under the action of the return spring (33) (E) moved. The recess (49) of his arm (24) takes the rocker arm (51) on its leg (50). This pivots about the bearing point (57), which exists between the bolt (56) and the bearing recess (55). Opposite the bearing point (57) there is a play (S2) between the bearing recess (55) and the bolt (56). By pivoting the switching rocker (51), its leg (52) moves the plunger (10) so that the free stroke (c) (see FIG. 3) is reduced, the edges (44) of the contact bridges (8, 9) approach. Under the action of the tensioned compression spring (26), the plunger (10) jumps over, so that the game (S2) disappears and the contact bridges (8, 9) detach from the contacts (4,5,6,7). In this intermediate state (see Fig. 8) there is a stroke (H2). The plunger (10) then moves into the position shown in FIG. 5 in linear motion. In this described switching-off process, the current insistence on stroke (H2) results in small arcs between the contacts than in the push-button switch according to FIGS. 1 to 4. Even if the contacts should stick in the position according to FIG. 7, the switching rocker (51) ensures a reliable opening of the contacts in the manner described.

List of reference symbols 04/94 Pt.

1

casing

2nd

Bottom part

3rd

Cover part

4-7

Contact

8.9

Contact bridge

10th

Plunger

11.12

Compression spring

13

Cones

14

Indentation

15

breakthrough

16

tongue

17th

Hump

18.19

first slope

20.21

second slope

22

Slide switch

23

Locating pin

24th

poor

25th

Continuation

26

Compression spring

27

Backdrop

28

Locking lever

29

hexagonal tenon

30th

score

31

Rounding

32

approach

33

Return spring

34

chamber

35

head Start

36

Weird

37

Ribs

38.39

Cones

40

drilling

41

edge

42.43

attack

44

edge

45

Rest

46

edge

47

Guide section

48

Switch contact

49

Recess

50

1st leg

51

Shift arm

52

2nd leg

53

circular opening

54

Cones

55

Bearing recess

56

fixed bolt

57

Depository

a

Stroke

b

Stroke

c

Free lift

d

Free lift

A

direction

E

Direction of indentation

H

Contact stroke

H1

Remaining stroke

H2

Stroke

L

Longitudinal axis

L1

Leg Length (50)

L2

Leg Length (52)

S1

game

S2

game

Z.

Direction of pull

Claims (4)

Pushbutton switch, in particular mains switch, with contacts (4 to 7) fixed to the housing and at least one contact bridge (8,9) movable by means of a spring plunger (10), with a spring switch (24, 25, 26) which is located between the spring plunger (10) and a manually operable slide switch (22) is effective, and with a latching device (27, 28) for the slide switch (22), the slide switch (22) alternately going into the switch-on position and the switch-off position when pressed (E),
characterized,
that a switch rocker (51) is provided between the slide switch (22) and the plunger (10), that the switch rocker (51) engages on the one hand on the slide switch (22) and on the other hand on the plunger (10) and is mounted on the housing so that the switch rocker ( 51) at the beginning of the switch-on and switch-off process the jump plunger (10) in the switch-on direction or switch-off direction forcibly takes along a section of the contact stroke (H) and after this section the jump switch (24, 25, 26) takes the plunger (10) into the switch-on position or off position. Pushbutton switch according to claim 1,
characterized,
that the housing-fixed mounting consists of a bearing recess (55) of the rocker arm (51) and a housing-fixed bolt (56), with games (S1, S2) both in the switched-on position and between the bolt (56) and the bearing recess (55) exist in the off position. Pushbutton switch according to claim 1 or 2,
characterized,
that the rocker arm (51) has a first leg (50) which engages in a recess (49) of the slide switch (22) and by means of which the slide switch (22) can be pivoted. Pushbutton switch according to one of the preceding claims,
characterized,
that the rocker arm (51) has a second leg (52) which pivots on the plunger (10), the plunger (10) being linearly displaceable by means of the leg (52).

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