FI78369C - MIKROSTROEMBRYTARE. - Google Patents

Description

1 78369

micro switch

TECHNICAL FIELD This invention relates to electrical engineering and in particular to microswitches.

The invention is useful as a limit switch in automated control and protection communication systems, in electrical drives of machines and mechanisms.

Generally, the contacts of the limit switches are changed by the movable shoulder (eccentric) of the machine, aligned with the operating part of the switch.

At low speeds of movement of the moving shoulder of the machine and the rate of contact change, which depends on the speed of the moving shoulder, as is the case with direct action switches, the time interval between the first contact of the electrical contacts and the moment when they reach sufficient contact pressure is relatively large.

Contacts under electrical load with insufficient contact pressure in a long-term closed position, as well as their slow replacement, can cause a number of serious faults: momentary disconnection, contact wear due to sparking, and even fusing.

25 Microswitches with a means of increasing the switching speed of the moving contacts are used for the purpose of eliminating contact damage at low speeds of the moving shoulder of the machines.

Background Information 30 A microswitch is known in the art (see U.S. Patent No. 2,728,826, International Patent Application No. 01/213/28), comprising fixed contacts mounted on a stationary substrate, a movable contact adapted to selectively switch to fixed contacts, and a means for moving the movable contact. The aid for moving the movable contact includes an operating lever 2 78369 and a contact lever connected in series and a spring. The operating lever and spring are attached to an insulating base. The movable contact is attached to the end of a contact lever connected to a spring.

5 In this microswitch, the contact pressure changes from the nominal value to zero when the operating lever moves to an operating point which makes the microswitch unreliable at low speeds of movement of the operating part, thus limiting the range of its application.

A microswitch is also known as disclosed in West German Patent No. 1,916,956, International Patent Application HOIH 13/28. This microswitch also comprises an insulating base 1 '(see Figures 1-4), fixed contacts 2', 3 'attached to the insulating base 1', a movable contact 4 ', adapted to selectively engage the fixed contacts 2' and 3 'and a movable contact for changing the contact 4 '. In this microswitch, the aid for changing the movable contact 4 'comprises the operating, contact and intermediate levers 5', 5 ', 7' and the base 20 'lever 8', which is a tension spring, respectively. The operating lever 5 'and the tension spring 8' are articulated to the insulating base 1 '. The one end of the contact lever 6 'is connected to the free end of the action lever 5', the point 0 and a movable contact 4 'and a movement limiting shoulder 9' attached to one end thereof. One end of the intermediate lever 25 'is articulated to the center of the contact lever 6', point 0 and the other end is connected to the free end of the tension spring 8 'and rests upwards against the movement limiting shoulder 9'.

In the initial position of the microswitch, the biased spring 8 '30 exerts a force P at the end of the intermediate lever 7' to which it is connected. The contact pressure P1 produced by the force P is equal to P> Sinot (Fig. 1), where Oi is the angle of inclination between the contact lever 6 'and the spring 8'.

The end of the action lever 5 'articulated with the kos-35 chain lever 6' (their connection point 0) moves under the influence of the force F 'in the direction of the force F' and when the point 0 3 78369 reaches the unstable position II of the contact lever 6 '(Fig. 2), the spring 8 'stretches, the intermediate lever 7' is parallel to the contact lever 6 ', the force P increases to P2 and the contact pressure P1 becomes equal to zero (P ^ = 0); since 5 angle Ot = 0.

When the point 0 crosses the line I-I, the position of the movable contact 4 'is changed. Slow (creeping) movement of the operating lever 5 'to the operating position, as described above, with the contacts 2', 4 'or 3', 4 'in the long-term closed-10 position under electrical load with insufficient contact pressure can cause momentary disconnection, contact wear due to sparking and even their merging.

In the case of the merging of the movable contacts 4 ', the fixed contacts 15 2' or 3 'when the operating lever 5' reaches the operating position, the change of position of the intermediate lever 7 'allows a rapid increase in the release force.

In the changed position of the movable contact 41 (Fig. 4), two forces act on the contact lever 6 '.

20 P. | = P 'Sin / 3 whereβ is the angle of inclination between the intermediate lever 7' and the spring 8 'and 25 P3 = P £ Siny = P' Sin y Cos β where * y is the angle of inclination between the intermediate lever 7 'and the contact lever 6'.

30 Then contact pressure

Pk = Ρΐ "P3 17 = P '(Sin / i - Siny Cos / S ^), where L and AL are the horizontal projection of the length 35 of the contact lever 61 and the horizontal projection of the partial length of the contact lever 61 between points 0 and 01.

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When the acting force F is removed from the operating lever 5 ', the contact lever 6', together with the operating lever 5 ', tends to return to the initial position under the action of the spring force P'.

When the angle β has decreased to the minimum value, the equilibrium state of 5 forces P 'Sin / ¾ = P' Siny Cos / 3 ^ occurs when the contact pressure is equal to 0.

10 Thus, in the known microswitch, the contact pressure changes from the nominal value to the minimum value at the speed of movement of the operating lever, and when the operating lever reaches the direct action position and also in a certain position before the state change, the contact pressure becomes equal to 0.

15 Presentation of the invention

It is an object of the invention to provide a microswitch in which the minimum arrangement and weight of the microswitch in the component arrangement mechanism to change the position of the movable contacts would allow a constant contact pressure during movement of the operating lever to the operating position, thus increasing its operational reliability.

This object is realized by means of a microswitch according to the invention comprising an insulating base, at least one fixed contact attached to the insulating base, means for moving the movable contact of at least one movable contact in contact with the fixed contact, the means comprising an operating lever connected to a contact lever and a spring arrangement comprising an intermediate lever and a spring connected to each other at one end thereof, the operating lever and one of the components of the spring arrangement being pivotable by fixed supports of the insulating base, the end lever end connected to the spring being supported by a stop formed by the contact to the free end of the lever while this same end supports the motion-35 depicts the contact. For this microswitch

II

5,7369 le is characterized in that the second component of the spring arrangement is attached to the end of the contact lever opposite the end supporting the movable contact such that the operating lever connection point to the contact lever is located between the contact lever of the second component of the spring assembly and the movable contact.

Such an arrangement of operating, intermediate and contact levers makes it possible to prevent faults by providing a constant contact pressure and to considerably increase the operational reliability of the microswitch 10. In addition, this is achieved by the very simple design, small size and mass of the microswitch.

Brief description of the drawings

The invention will now be explained with reference to its embodiments, which are shown in the accompanying drawings, in which:

Figures 1-4 are a schematic representation of a prior art microswitch, a step of direct operation and a state change of device to change the position of movable contacts; Fig. 5 is a schematic diagram of an embodiment of a microswitch of the invention;

Fig. 6 is a detailed view of the microswitch shown in Fig. 5, axonometric view;

Fig. 7 schematically shows a second embodiment of a microswitch 25 of the invention, an overview;

Fig. 8 is a detailed view of the microswitch shown in Fig. 7, axonometric view;

Figure 9 is a general schematic diagram of a further modification of a microswitch of the invention; Fig. 10 is a detailed view of the microswitch shown in Fig. 9, axonometric view;

Figures 11-12 show a mechanical diagram of a microswitch of the invention;

Figure 13 shows a diagram of changes in contact pressure 35 in a microswitch of the invention.

6 78369

Best Mode for Carrying Out the Invention

Referring to Figures 5-12, the microswitch comprises an insulating base 1, at least one pair of fixed contacts 2, 3 attached to this base 1 (Figures 5, 6, 9, 5 10), at least one movable contact 4 adapted to selectively engage the fixed contacts 2,3 .

A modification of the microswitch of the invention with two pairs of fixed contacts and two movable contacts is shown in Figures 7.8. The operating part 5 contacts the operating lever 6. The aid for changing the position of the movable contacts 4 comprises an operating lever 6, a contact lever 7 and a spring arrangement comprising an intermediate lever 8 and a spring 9 connected to each other at one end. The other end of the operating lever 6 is articulated to the insulating base 1 by a conductor 19 (Figs. 5 and 9) 15 (here and thereafter the articulation is performed, depending on the specific case, by means of angular contact holders).

The other end 11 of the operating lever 6 is likewise connected to the contact lever 7 by means of edge bearing holders. A movable contact 4 20 and a movement limiting shoulder 13 are mounted on the free end 1 of the contact lever 7. The intermediate lever 8 and the spring 9 are articulated to each other at the ends 14, 15 and against the restrictive shoulder 13. The other end 16 of the intermediate lever 8 is articulated to the contact lever 7 at a point adjacent to the connection point of the latter and the operating lever 6 25 and the other end 7 of the spring 9 is articulated to the insulating base. In the microswitch according to Fig. 7, the operating lever 6 is mounted from the articulated end 10 to a fixed support 20 separated from the insulating base 1 and the support lever 8 is articulated at its end to a fixed support 21 connected to the insulating base 1.

According to the invention, the end 16 of the intermediate lever 8 is connected to the end of the contact lever 7 opposite the top 12, on which the movable contact 4 and the movement limiting shoulder 13 are mounted and the operating lever 6 is connected to the middle part of the contact lever 35 between the movable contact lever 7 and the intermediate lever 8. This makes it possible to achieve a constant contact pressure in the microswitch, thus preventing possible 7 78369 fault situations / which occurred in the prior art microswitches and increasing its operational reliability, with a fairly simple structure and small space and mass.

Possible changes in the operating, contact, intermediate and support levers 6, 7, 8 and 9, respectively, and their arrangement in the microswitch of the invention are shown in Figures 5-10. Such microswitch functions are as follows. In the initial position of the microswitch, the biased spring 9 10 (support lever) acts with a force P on the end 14 of the intermediate lever 8 (Fig. 11).

The contact pressure thus obtained consists of two components

15 P = P + P

* k * 1 * 3 L

where

P1 = P SinoC

P ^ = P2 Sin / ¾ = P · Sin / 3 · Cos oi 20 ot is the inclination angle between the intermediate lever 8 and the spring 9/3 is the inclination angle AL between the intermediate lever 8 and the contact lever 7 is a horizontal projection of a part of the contact lever between the connecting lever 8 and the contact lever 7 and the contact lever 7 and the connection point 25 L of the operating lever 6 has a horizontal projection of the contact lever 7

Under the influence of an external force F which reaches the value F.j (see Fig. 12), the action lever 6 moves in the direction of this force and the intermediate lever 8 changes its position relative to the spring 9.

30 When point A reaches position A ^ when it reaches line I-I, i. straight, the unstable position of the intermediate lever 8, the contact pressure is

Pk = P3 TT 'P2 Sin / »f 35 β 78369

A diagram of the changes in contact pressure during the movement of the operating lever 6 is shown in Fig. 13.

Since detailed embodiments of the invention have been shown and described, various modifications thereof will be apparent to those skilled in the art, and therefore the invention is not intended to be limited to the disclosed embodiments or details thereof, and changes may be made within the spirit and scope of the invention.

Il

Claims (1)

A microswitch comprising an insulating base (1), at least one fixed contact (3) attached to the insulating base (1), at least one movable contact (4) contacting the fixed contact (3), means for moving the movable contact to which the means include an operating lever (6) connected to the contact lever (7) and a spring arrangement comprising an intermediate lever (8) 10 and a spring (9) connected to each other at one end (15) of the latter, the operating lever (6) and the second (8) of the components of the spring arrangement are rotatable by fixed supports (20, 21) of the insulating base (21), the end (14) of the intermediate lever (8) connected to the spring (9) resting on a stop (13) formed by the contact lever ( 7) at the free end when this same end supports the movable contact (4), characterized in that the second component (9) of the spring arrangement is attached to the end (18) of the contact lever (7) opposite the end supporting the movable contact (20). a contact (4) such that the connection point (11) of the operating lever (6) to the contact lever (7) is located between the connection point contact lever (7) of the second component (9) of the spring arrangement and the movable contact (4).