FR2581236A1 - MICRO SWITCH AND ITS CONTROL MECHANISM - Google Patents

Abstract

MICRO-SWITCH CONTAINING A BASE, FIXED CONTACT ELEMENTS FIXED ON THE BASE, A CONTROL LEVER CONNECTED WITH THE POSSIBILITY OF ANGULAR MOVEMENT TO THE BASE AND TO A CONTACT LEVER. THE OTHER END 17 OF A SPRING 11 IS FIXED ON THE BASE 1 IN THE ZONE BETWEEN THE VERTICAL PLANS II, II-II PASSING THROUGH ONE, BY THE CONNECTION POINT 18 OF THE OTHER END 15 OF A INTERMEDIATE LEVER 12 TO CONTACT LEVER 6 AND THE OTHER, GOING THROUGH A MOBILE CONTACT BODY 9. APPLICATION TO AUTOMATIC SYSTEMS FOR CONTROL OF ELECTRICAL CONTROLS AND SIGNALING OF MACHINES AND MECHANISMS.

Description

The present invention applies to the field of electrical engineering,

  and more precisely, micro-switches.

  The invention can be applied to position switches (from

  limit switches) used in signaling and control systems

  the automatic electrical controls of machines and mechanisms.

  Switching of the position switch (limit switch) contacts usually occurs under the action of a movable stop

  (of a cam) machine on a control element of the switch.

  In the case of low speeds of movement of the moving machine stop and when the switching speed of the contacts depends on the

  speed of movement of the movable stop, as in the case of

  Directly acting breakers, the time interval between the first moment when the charged contact elements come into contact and the moment when a sufficient contact pressure is reached, is relatively long. The relatively prolonged stay of contacts in the state

  closed with an electrical charge and insufficient contact

  These, as well as their slow switching, can cause serious damage such as softening, burning of contacts, and even soldering. To avoid deterioration of the contacts in the event of low speeds of movement of the mobile stop of the machines, switches with an acceleration mechanism are used.

  switching process of mobile contacts.

  A microswitch is known (US Pat. No. 2,728,826) comprising a base, movable contacts fixed on the base, a control lever connected to the base, with the possibility of angular displacement, and a contact lever connected to the lever of FIG. control with possibility of angular deflection. At the free end of the contact lever is fixed a movable contact element. The microswitch also comprises a spring connected at one end to the end of the contact lever carrying the movable contact element, and by its other

end to the base.

  When an external force acts on the control lever and under this action the junction point of the control lever and the contact lever reaches the longitudinal axis of a spring, the switching

contacts occur.

  In the initial position of the microswitch, the contact lever is located at an angle α relative to the longitudinal axis of the spring and the contact pressure is equal to the force of the spring multiplied by sin a. With the control lever in the position where the contact lever is in the longitudinal axis of the spring, the angle

  a is equal to zero and the contact pressure is also zero.

  It can be seen that in the known microswitch, when the control lever moves, the contact pressure varies from the nominal value to the minimum value during the movement of the control lever.

  control and becomes even zero in the operating position of the micro-

  light switch. This micro-switch does not ensure reliable service in the case of a slow motion and in case of change

  the operating direction of the control lever and in the presence of vibra-

and shocks.

  There is also known a microswitch (German Patent 1,916,958) comprising a base, fixed movable contacts on the base, a control lever connected to the base with the possibility of angular movement and a contact lever connected to the lever of control with possibility of angular deflection. At the free end of the contact lever is fixed a movable contact element. The microswitch also comprises a mechanism for switching the movable contact element in the form of a spring and an intermediate lever.

  which are connected to each other at one end and at the end

  mity of the contact lever to which is fixed the movable contact element, and can move in a direction perpendicular to the contact lever. The other end of the spring is connected to the base and the other end of the intermediate lever is connected to the contact lever with the possibility of angular displacement so that the point of attachment of the spring to the base is outside the o area

  find the micro-switch elements behind the connection point

  intermediate lever and contact lever.

  When an external force acts on the control lever and the point of connection of the intermediate lever and the contact lever intersects the longitudinal axis of the spring, switching of the moving contact occurs. In the known microswitch, the contact lever is biased by two moments of forces in opposite directions, caused by the action of the reaction force of the spring applied to the intermediate lever: a moment of forces directed perpendicularly to the intermediate lever and applied at the point of connection of the spring and the intermediate lever, another moment of forces caused by the action of the component of the spring force oriented along the intermediate lever and applied

  contact lever at the point of connection to the intermediate lever

  diary. For a certain position of the drive lever, these two moments of forces acting on the contact lever are annihilated

  reciprocally and the contact pressure then becomes zero.

  We see that in this known microswitch, during the

  of the control lever, the contact pressure varies with the speed of movement of the control lever from a nominal

  a minimum value, and for a certain position of the control lever

  close to the position at which the switching of the moving contacts occurs, it is zero. This does not ensure a

  operation without hazard of the microswitch in the case of a

  slow or reversible operation of the control lever, as well as in case of

shocks and vibrations.

  The aim of the invention is to propose a microswitch where the device

  reciprocal nature of the various elements makes it possible to improve the reliability of

  operation of the microswitch.

  For this purpose, in a microswitch comprising a base, fixed contact elements fixed on the base, a control lever connected to the base with the possibility of angular displacement, a contact lever connected to the control lever with possibility angular displacement, a movable contact member fixed on the free end of the contact lever, a switching mechanism of the movable contact member, made in the form of a spring and an intermediate lever, which are connected between them by one of their ends and at the end of the contact lever, on which is fixed the movable contact member, and which can move in a direction perpendicular to the contact lever, the other end of the spring or the intermediate lever being connected to the contact lever between the point of connection of the contact lever to the control lever and the movable contact member, and the other end of the intermediate lever or resp. ectively spring being connected to the base, according to the invention, the other end

  of the spring of the switching mechanism of the movable contact member is -

  fixed on the base in the zone between vertical planes passing one through the connection point of the other end of the intermediate lever of the switching mechanism of the movable contact member with the contact lever and the other passing through the movable contact member. Such an embodiment of the microswitch ensures a permanent contact pressure during the movement of the control lever to the operating position, thereby improving the reliability of the microswitch in the presence of vibrations and shocks, as well as during slow and intermittent movements of the control device acting on the microswitch. Improved service reliability is thus achieved with a simpler arrangement of the

  microswitch, as well as reduced bulk and mass.

  Other purposes, advantages and features of the invention

  will appear on reading the following description, made

  FIG. 1 is a kinematic diagram of a first variant of FIG.

  realization of a microswitch according to the invention

  tion, represented in initial position; - Figure 2 is a kinematic diagram of the first embodiment of the microswitch shown in a position of the control lever which is close to the position where occurs the switching of the movable contact element; - Figure 3 is a longitudinal sectional view of a second embodiment of a microswitch according to the invention, shown in the initial position; - Figure 4 is a longitudinal section of the second embodiment of the microswitch shown in a position of the drive lever which is close to the position o occurs switching of the movable contacts; - Figure 5a, b c shows an exploded view of the details of the second embodiment of the microswitch according to the invention; - Figure 6 is a longitudinal sectional view of a third embodiment of a microswitch according to the invention, shown in the initial position; FIG. 7 is a separate view of the details of a third embodiment of a microswitch according to the invention; FIG. 8 is a graph illustrating the variation of the contact pressure for the first variant of FIG.

  realization of the microswitch according to the invention.

  The microswitch comprises a base 1 (FIGS. 1, 2)

  made of an insulating material, stationary contact elements 2, 3, fixed

  on the base 1, a control lever 4 connected by its end 5 to -

  the base 1 with the possibility of angular displacement and a contact lever 6, connected at its end 7 to the other end 8 of the control lever 4 with the possibility of angular displacement. An organ of

  movable contact 9 is fixed to the free end 10 of the contact lever 6.

  The microswitch also has a switching mechanism of the movable contact element, made in the form of a spring 11 and

  an intermediate lever 12 which are connected by one of their ends

  13 and 14 respectively of the spring 11 and the lever 12, one to

  the other and at the end 10 of the contact lever 6 and can move

  in a direction perpendicular to the contact lever 6.

  The other end 15 of the intermediate lever 12 is connected to the contact lever 6 between the point 16 connecting the lever of

  contact 6 at the control lever 4 and the movable contact member 9.

  The other end 17 of the spring 11 is connected to the base in the zone between the vertical planes (shown by their traces II and II-II in Figures 1 and 2) passing through the connection point 18 of the lever 12 to contact lever 6 and by the movable contact 9. Lever

  4 is urged by a control member 19.

  A second embodiment of the microswitch is proposed which comprises a base 20 (FIGS. 3, 4) made in one

  insulating material, fixed contact elements 21, 22 fixed to the

  20, a control lever 23 and a contact lever 24 made to form an assembly and is in the form of a resilient piece sheet of thin electroconductive material (Figure 5a). The control lever 23 (Figures 3, 4) is fixed at its end 25 to the base 20 by means of an electrical conductor 26, with the possibility of angular movement. A movable contact member 27 is

  fixed on the free end 28 of the contact lever 24.

  The switching mechanism of the movable contact member consists of an intermediate lever 29 (Figure 5b) stirrup-shaped and a spring 30 (Figure 5c) in the form of a bent plate

thin in an elastic material.

  The respective ends 31, 32 (Figures 3, 4) of the spring 30 and the intermediate lever 29, are interconnected. At the end 32 of the intermediate lever 29 are provided hooking cutouts 33, 34 (FIGS. 5b) by means of which this end 32 (FIGS. 3, 4) is connected to the end 28 of the contact lever 24 on which is On the other hand, the ends 31 and 32, respectively of the spring 30 and the intermediate lever 29, can move, in the direction perpendicular to the contact lever 24, by a distance equal to the distance between the lips of the engagement cutouts 33, 34 (FIG. 5b) of the intermediate lever 29. The other end 35 (FIGS. 3, 4) of the spring 30 is fixed to the base 20 via the driver 26. The other end 36 of the intermediate lever 29 is hooked to the contact lever 24. The attachment point 37 of the end 36 of the intermediate lever 29 on the contact lever 24 is situated between the junction point 38 (FIG. FIG. 5a) of the contact lever 24 with the lever 23 and the movable contact member 27. The connection point 38 of the contact lever 24 with the control lever 23 is located on the elastic part formed by the contact lever 24 and the control lever 23, in the zone of his

  maximum bending. Point 39 (figures 3, 4) for fixing the

  35 of the spring 30 on the electrical conductor 26 of the base 20, is in the area between the vertical planes (shown by their traces IV-IV and III-III in Figures 3, 4) passing, one , by

  point 38 connecting the contact lever 24 to the control lever

  23 and the other by the movable contact 27. The control lever 23 is

  urged by a control member 40.

  A third embodiment of the micro-switch is proposed. In this case, the microswitch comprises a base 41 (FIGS. 6, 7) made of an insulating material, fixed contact elements 42, 43 fixed to the base 41, a control lever 44 and a contact lever. 45 forming a set and made as a piece

  in the form of an elastic electroconductive sheet (FIG.

  re 7). The control lever 44 (FIG. 6) is connected by its end

  46 to the base 41 by means of an electrical conductor 47 with the possibility of

  angular deflection ability. A movable contact member 48 is fixed

  at the free end 49 of the contact lever 45.

  The switching mechanism of the movable contact member consists of an intermediate lever 50 in the form of a stirrup, and a helical spring 51. The ends 52, 53, respectively of the spring 51 and of the intermediate lever 50, are interconnected. At the end of 53

  intermediate lever 50 (FIG. 7) are provided the hooking cutouts

  54, by means of which the end 53 of the intermediate lever 50 is hooked to the end 49 of the contact lever 45, on which is fixed the movable contact member 48. Moreover, the end 53 of the intermediate lever 50, to which is attached the spring 51, can move in the direction perpendicular to the contact lever 45 of a

  distance equal to the distance between the lips of the cutouts of

  chage 54 of the intermediate lever 50.

  The other end 55 (Figure 6) of the spring 51 is attached to the contact lever 45 while the other end 56 of the intermediate lever 50 is attached to the electrical conductor 47 of the base 41. The attachment point 57 of the end 55 of the spring 51 on the contact lever 45 is located between the zone 58 connecting the contact lever 45 to the

  lever 44 and the movable contact member 48. The point of access

  59 of the intermediate lever 50 on the electrical conductor 47 of the base 41 is in the area between the vertical planes (shown by their traces VI-VI and VV in Figure 6), which pass, one, by the point 57 for fixing the end 55 of the spring 51 on the contact lever 45 and the other, by the movable contact 48. Shoulders 60 (6, 7) of the control lever 44 are solicited

by a control member 61.

  The first variant of the micro-switch that has just been

  described works as follows. In the initial position of the micro-

  switch, the spring 11 previously compressed (Figure 1) reacts with a force P on the end 14 of the intermediate lever 12. The contact lever 6 is biased by the same direction of moments M1 and M2, which are generated by the vertical component P1 and the component

  horizontal P2 of the force P developed by the spring 11.

8 2581236

  The moment M1 created by the force P1 applied at point 16 of the connection

  The operation of the control lever 4 to the contact lever 6 is equal to: M1 = P1. L = P.sin a.L

  The moment M2 due to the force P3 applied to the connection point 18

  from the intermediate lever 12 to the contact lever 6, is equal to: M2 = P3.L1 = P.sin B.cos a.L1 o L, L1 are the geometrical dimensions of the contact lever 6; a is the angle of inclination of the intermediate lever 12 with respect to the spring 11; B is the angle of inclination of the intermediate lever 12 by

relative to the contact lever 6.

  The distance between the movable contact member 9 and the ends

  13, 14 respectively of the spring 11 and the intermediate lever 12 being very small, one can obtain the numerical value of the contact pressure Pko by the formula: Pko P.sin a.sin + P.sin.cos a1 Under the action of an external force F applied to the control member 19 and which reaches a value F1 (Figure 2), the control lever 4 moves in the direction of action of this force, while the intermediate lever 12 modifies his position with respect to

spring 11.

  When the connection point 16 of the contact lever 6 and the control lever 4 (Figure 2) reaches the position, for which it is located on a line passing through the ends 13 and 17 of the spring 11 (unstable position line of the spring 11), the angle becomes zero and the angle B is equal to the initial angle. The contact pressure Pk

  (FIG. 8) is then formed under the action of the contact lever 6 (FIG.

  re 2) subjected to the action of a single moment of force in the previous direction, as in the initial position: M2 P '3 L1 = P 2.sin.L1 = P'.sin. cos OL Hence the contact pressure is reduced: Pl L p '3.L1 kl - L o P' is the reaction force of the spring 11 in the compressed state, P'3 is the force applied to the point 16 connecting the lever

  4 to the contact lever 6 in the operating position

  tioning. When the position where the connection point 16 of the contact lever 6 to the control lever 4 coincides with the line passing through the ends 13 and 17 of the spring 11, there is a sudden switching of the movable contact member 9 which is moves to come into contact with the fixed contact element 3. When the external force of the actuating member 19 stops urging the control element 19,

  all moving parts of the microswitch come back under

  spring 11 into the initial position.

  By choosing a specific ratio between the geometric

  L1 and L of the micro-switch parts and the rigidity of the

  fate 11 generating forces P and P ', we can ensure in the micro-

  switch, during the displacement of the control member 19, to its operating position, a constant contact pressure

  Pk 'that is to say that Pko = Pk1 (Figure 8).

  The second variant embodiment of the micro-switch function-

  do it the following way. During the action of an external force F1 (FIG. 3) on the control member 40 subjected to the force F (FIG. 4), the control lever 23 pivots at an angle with respect to the electric conductor 26 of FIG. the base 20. When the contact lever 24 reaches the position for which the point 38 connecting the intermediate lever 29 to the contact lever 24 intersects the line passing through the ends 31, 35 of the spring 24 (unstable position line of the spring 24),

  switching of the movable contact element 27 occurs.

  When the control element 40 is no longer stressed by an external force, all the moving parts of the microswitch

  return to the initial position under the action of the spring 30.

  The microswitch according to the third embodiment operates in a similar manner to that indicated above. We obtain

  also in this case a constant contact pressure during the

  of the control member 61 (FIG. 6) to the operating position of the microswitch, thanks to the action on the contact lever 45 in the initial state of two moments of forces oriented in the same direction. sense, generated by the action of the reaction force of the spring 51, and also by the action of a slightly increased moment of the reaction force of the compressed spring 51 in the position of the lever of

  command 44 which is close to the position o occurs the operation-

the micro-switch.

  The constant contact pressure obtained in the micro-interrup-

  According to the invention, it is possible to improve its stability with respect to vibrations and shocks and to ensure trouble-free operation in control circuits traversed by low currents, as well as high switching power and good resistance. to wear even for a low speed of movement of the control member, which allows, therefore, to improve the reliability of the microswitch

  under severe conditions of use.

  Of course, the present invention is not limited to the embodiments described and shown, but it is capable of numerous variants accessible to those skilled in the art without it being possible to

  departs from the spirit of the invention.

Claims (1)

CLAIM   1.- Micro-switch comprising a base, fixed fixed contact elements on the base, a control lever connected to the base with the possibility of angular displacement, a contact lever connected to the control lever with possibility of angular movement , a mobile contact member fixed on the free end of the contact lever, a switching mechanism of the movable contact member, in the form of a spring and an intermediate lever which are interconnected by the one of their ends and at the end of the contact lever on which is fixed the movable contact member, and which can move in a direction perpendicular to the contact lever, the other end of the spring or the intermediate lever being connected to the contact lever between the connection point of the contact lever   the control lever and the movable contact member, and the other end   mity of the intermediate lever or the spring being connected   at the base, characterized in that the other end (17) of the   fate (11) of the switching mechanism of the movable contact member (9)   is fixed on the base (1) in the zone between vertical planes   passing, one through the connection point (18) of the other end   mité (15) of the intermediate lever (12) of the switching mechanism of the movable contact member with the contact lever (6) and the other,   passing through the movable contact member (9).