DE3321561A1 - Switching device for a temperature switch or pressure switch - Google Patents

Abstract

A switching device for a temperature switch or pressure switch has, in a housing (1), a snap-action switch (6) which has a contact rivet (14) which is always held against one of two fixed contacts (11, 12) by means of a contact spring (15). The snap-action switch (6) is operated by means of an operating lever (21) which is displaced by a plunger (5). A compression spring (29) is used to reset the plunger (5). This compression spring (29) is supported on the operating lever (21), above the plunger (5), and on an end insulating material panel (7) of the housing (1) of the switching device. In order to make possible this arrangement of the compression spring, a slot-shaped passage (28) is provided in a tongue (16) of the contact spring (15), and the compression spring (29) is guided through said passage (28). <IMAGE>

Description

-Λ-

Switching device for a temperature or pressure switch

The invention relates to a switching device for a temperature or pressure switch, in which a a measuring element causing a change in distance and force is connected to a snap switch, which has a pivotably mounted operating lever, a consisting of a leaf spring, a contact spring carrying a Hontakt rivet and one approximately in the plane the contact spring lying leaf spring-shaped arched Has tongue which at a first end with the contact spring in! Mäh the contact rivet is connected and at a second end facing away from the contact rivet is clamped, can be lowered into a first stable position with respect to the contact spring by the actuating lever and can be raised into a second position, the contact rivet in at least one position is printed on a fixed contact and for this purpose the operating lever with the formation of such kinematics, is connected to the contact spring that when the snap switch is activated, the

Fixed contact automatically moves the pressed contact rivet parallel to the contact surface before it lifts off the fixed contact at the beginning of a switching process. Such a switching device is the subject of DE-OS 27 kl 325.

In the known switching device, the contact spring inevitably also acts in the return direction of the plunger. Much greater forces are required to reset the plunger than to bring about the jump effect. Since the Hontaktfeder must have a high flexural strength, its material thickness is limited, so that its actuation force is often not sufficient to return the plunger to its starting position. To solve this problem, one could think of arranging an additional return spring in the switching device. As can be read in DE-PS Zk hk 931, however, switching devices with a separate return spring have the disadvantage that they are considerably larger in volume than switching devices in which the contact spring is also a return spring.

The invention is based on the object in a switching device of the type mentioned above separate return spring to be arranged in such a way that rnögliehst little or no additional space is required.

According to the invention, this object is achieved by that the Hontaktfeder has a central passage through which a compression spring serving as a return spring is performed, on the one hand on the actuating lever on the side of the plunger abgeuiendet, on the other hand at the frontal boundary of the Switching device is supported.

The compression spring arranged according to the invention makes use of the space that is in any case above the tappet between the actuating lever and the frontal boundary. As a result, the switching device according to the invention is no larger than that according to DE-OS 27 kl 325 or that according to DE-PS 2 * t hh 931. Thanks to the invention, the spring causing the snap effect can be dimensioned weakly so that it has a high flexural fatigue strength . With such a weakly dimensioned contact spring, the switching point of the switching device can be determined very precisely and a low hysteresis can be achieved. In addition to these advantages, it should be emphasized that the switching device according to the invention is very simple in construction and therefore cheap to manufacture.

The switching point of the switching device can be adjusted in a very simple way if the compression spring is supported against a stud screw adjustably screwed into the insulating material plate. Farther it is possible for different applications by means of a correspondingly large stroke of the stud screw set different switching points.

Another advantageous embodiment of the invention is that the passage extends in the main direction the contact spring is a running slot. Through such a slot as a passage the contact spring can bulge relatively far from one switch position to the other without using the Collide compression spring.

The invention can be implemented in numerous ways to. One of them is shown in the drawing and is described below. Show it

Figure 1 - the switching device according to the invention in longitudinal section;

Figure 2 - a three-dimensional representation of the essential for the invention contact spring Switching device according to Figure 1.

In Figure 1, 1 is a screw-in housing of Switching device for a pressure switch, in the lower cylindrical extension of which has a bore 2 leads to a pressure chamber 3 which is delimited by an elastic membrane 4 on which a plunger 5 is seated. The plunger 5 acts on a snap switch, denoted as a whole by S, which is on an insulating material plate 7 is constructed. The insulating plate 7 is held in the housing 1, from which three electrical Connections B, 9, 10 protrude.

In the interior of the housing 1, the connection 9 has a first fixed contact 11, to which a second fixed contact 12 faces at a vertical distance and which is connected to the terminal 10. Between the two fixed contacts 11, 12, a contact rivet 14, which is riveted to a contact spring 15, is movable. The contact spring 15, which is shown greatly enlarged in Figure 2, is a leaf spring with a approximately U-shaped recess formed, the recess forming a curved tongue 16 which between two edge strips of the contact spring 15 included without contact is. In the area of the contact rivet 14, the curved tongue 16 goes with a first end 17 into the Contact spring 15 over. The second end of the tongue 16

As FIG. 1 shows, 3D lies in a groove 19, below the contact spring 15, in the first stable one shown Switch position.

The l \! Ut 19 is cut out from a bearing tongue 20 with a vertical section, which is cut through the insulating material plate 7 passes through and merges into the connection 8.

The operating lever 21 has a first section 22, which rests on the plunger 5. Furthermore, the actuating lever 21 on the bearing tongue 20 is pivotable stored. At the end remote from the plunger 5, the actuating lever 21 is a section 23 bent over through the approximately U-shaped opening of the end extended beyond the bearing tongue 2D 24 of the contact spring 15 extends into it.

In the drawn stable first position the plunger 5 is at its lowest point, in which the pressure is relatively low. The rising Pressure on and thereby the plunger 5 is pushed upwards, so this movement is transmitted to the actuating lever 21, which executes a pivoting movement and with its section 23 pulls the contact spring 15 to the left, since the contact rivet 14 is still printed on the first fixed contact 11 a frictional movement towards the contact surfaces arises. In doing so, the arched tongue 16 is pressed together further.

When the plunger 5 is raised, the contact spring 15 only snaps into its second position when the extended end 24 of the contact spring 15 is lowered below the height of the groove 19. Then the snap takes place under the action of the tension of the contact spring 15 and the bent tongue and then the contact rivet 14 is on the second fixed contact 12 at.

Then again by lowering the pressure of the plunger 5 drops and exerts less pressure on the actuating caliper 21, the contact rivet 1 * f is through the force of the curved tongue 16 initially on the fixed contact 12 in the plane of the contact surfaces postponed. Only then, when the end 29 of the contact spring 15 is pivoted above the groove 19 again is, the contact spring 15 is snapped into the position shown in the drawing.

Before each switching process, the switching contact from which the contact rivet is cleaned is cleaned by friction wants to take off.

FIG. 2 shows that the contact spring 15 has a bend on each of its two long sides 25/26, each of which comprises the entire edge strip on both sides of the tongue 16. For the invention It is essential that the contact spring 15 has a passage 2B in the form of a slot within the tongue 16 Has. As FIG. 1 shows, a compression spring 29, which is located on the actuating lever, is guided through this passage 2B 21 on the side of the first section 22 facing away from the plunger 5 and on a stud screw 3D supports. The stud screw 3D is screwed into the insulating material plate 7 in alignment with the plunger 5.

The plunger 5 is always biased in the return direction by the compression spring 29. By adjusting the Stud 3D is this restoring force and thus the switching point of the switching device can be changed.

Claims (3)

Number:
Int. Cl. ³ :
Registration date:
Disclosure day: H 01 H 35/34 June 15, 1983 December 20, 1984