EP0607567B1 - Push-button switch - Google Patents

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 being pressed in 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 also 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.

The object of the invention is to propose a push button switch of the type mentioned, in which manual incorrect actuations can hardly lead to increased wear and to functional uncertainty.

According to the invention, the above object is achieved in a pushbutton switch of the type mentioned at the outset in that a friction surface pairing is provided between the plunger and a part fixed to the housing, and in that the friction surface pairing shortly before the snap action of the spring switch initiated by displacement of the slide switch leads to increased friction between the plunger and leads to the housing-fixed part and thereby delays the snap-in of the plunger.

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 transition point is therefore only reached when the springs are in a stronger state of tension than without deliberate delay in the movement of the plunger before the point of change; 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.

In a preferred embodiment of the invention, a further friction surface pairing is provided between the plunger and the part fixed to the housing. This allows the movement of the plunger to be braked before the contact bridge strikes the contacts fixed to the housing, as a result of which bouncing of the contacts is suppressed.

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 Drucktastenschalters in Einschaltstellung.

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 view corresponding to Figure 2 of the push button switch in the on 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, with 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 hit the contacts (4.5 and 6.7) when braked. 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 that is not provided for the actuation of the switch, then the locking device, namely the link (27) or the locking lever (28), is used 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 so far in such an actuation 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 snap switch from the switched-on position to 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 so large that the pin (29) of the locking lever (28) goes 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 switched-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 being affected however, can bring the contact bridges into a state in which they are not in contact with the contacts (4.5 or 6.7). 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 functions described. 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). In reverse of the conditions described, it is also 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.

Reference number list 01/93 EP

Claims (12)

1. A push-button switch, in particular a mains switch, having housing-secured contacts (4 to 7) and at least one contact bridge (8, 9), which is movable by means of a snap-action plunger (10), having a snap-action switch mechanism (24, 25, 26) which is operative between the snap-action plunger (10) and a sliding switch (22) which can be manually actuated, and having a locking device (27, 28) for the sliding switch (22), with the sliding switch (22) going alternately into the on-position and the off-position when it is pushed in (E), characterised in that provided between the snap-action plunger (10) and a housing-secured portion (2, 17), there is a pair of friction surfaces (18, 19), and in that shortly before the snapping of the snap-action switch mechanism (24, 25, 26), which snapping is initiated by shifting the sliding switch (22), the pair of friction surfaces leads to an increased friction between the snap-action plunger (10) and the housing-secured portion (2, 17) and in this way delays the snapping of the snap-action plunger (10).
2. Push-button switch according to claim 1, characterised in that the one friction surface is formed by a first sloping surface (18) of the housing-secured portion (17) and the other friction surface is formed by a first sloping surface (19) of an elastic-spring-like tongue (16) of the snap-action plunger (10), with the first sloping surfaces (18, 19) touching against each other when the snap-action plunger (10) is shifted from the on-position into the off-position.
3. Push-button switch according to claim 1 or 2, characterised in that provided between the snap-action plunger (10) and the housing-secured portion (2, 17), there is a further pair of friction surfaces (20, 21), which restrains the movement of the snap-action plunger (10) before the on-position is reached.
4. Push-button switch according to claim 3, characterised in that the one friction surface of the further pair of friction surfaces is formed on a second sloping surface (20) of the housing-secured portion (17) and the other friction surface of the further pair of friction surfaces is formed on a second sloping surface (21) of an elastic-spring-like tongue (16) of the snap-action plunger (10), with the second sloping surfaces (20, 21) touching against each other when the snap-action plunger (10) is shifted from the off-position into the on-position.
5. Push-button switch according to one of the preceding claims 2 to 4, characterised in that the first sloping surfaces and the second sloping surfaces (18, 20) of the housing-secured portion (2) are formed on both sides of a protrusion (17) of the housing-secured portion (2), and the first sloping surface (19) and the second sloping surface (21) are formed on the same tongue (16) of the snap-action plunger (10).
6. Push-button switch according to one of the preceding claims, characterised in that the first pair of friction surfaces (18, 19) restrains the snap-action plunger (10) more strongly than the further pair of friction surfaces (20, 21).
7. Push-button switch according to claim 6, characterised in that the first sloping surfaces (18, 19) are steeper than the second sloping surfaces (20, 21).
8. Push-button switch according to one of the preceding claims, characterised in that in the on-position and/or the off-position of the snap-action plunger (10) there is a clearance (a and d respectively) between the sloping surfaces (18, 19 and 20, 21 respectively).
9. Push-button switch according to one of the preceding claims, characterised in that in the on-position of the snap-action plunger (10) there is a clearance (c) between an edge (44) of the snap-action plunger (10) and the contact bridge (8, 9), with the edge (44) moving the contact bridge (8, 9) from the on-position into the off-position.
10. Push-button switch according to claim 9, characterised in that the clearance (c) is larger than the clearance (d) which is clearance between the sloping surfaces (18, 19) in the on-position.
11. Push-button switch according to one of the preceding claims, characterised in that the contact bridge (8, 9) is supported at the snap-action plunger (10) with a compression spring (11 and 12 respectively).
12. Push-button switch according to one of the preceding claims, characterised in that the locking device has as locking pieces a connecting link (27) and a locking lever (28) which engages therein, and in that in the event of a manual application of force to the sliding switch (22) in the opposite direction to the direction of pushing in (E), in a pulling direction (Z), the two engaged locking pieces (27, 28) release the sliding switch (22) for a movement in the pulling direction (Z).

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