Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
SECURITY ELECTRIC SWITCH WITH IMPROVED CONTACT ASSEMBLY
Document Type and Number:
WIPO Patent Application WO/2018/190777
Kind Code:
A1
Abstract:
The purpose of the invention is to improve a security electric switch by increasing its reliability and also by simplification thereof. The switch according to the invention said switch assembly (2) consists of an immovable contact member (21), which is made of an electric conductive material and is electrically connected with said coil (31) of the interrupting assembly (3), which coil is electrically connected with said first contacting terminal (13) on the casing (1) of the switch, by which said immovable contact member is arranged within said casing (1) outside of said interrupting assembly (3) and on that side thereof, which is faced towards said seat (11), as well as of a movable contact member (22), which is also made of an electric conductive material and is inside of said casing (1) of the switch arranged adjacent to said immovable contact member (21) and is electrically connected with the other connecting terminal (14) on the casing (1) of the switch, wherein said movable contact member (22) is pivotally embedded within a cradle (220), which is formed on a free end portion of a cantilever beam (221) in the area in front of said needle (32) of said interrupting assembly (3) and is mechanically and electrically connected with said second connecting terminal (14), so that said movable contact member (22), which is embedded in said cradle (220), is pressed towards said immovable contact member (21 ) by means of a spring (222), by which it is supported in the adjacency of said cradle (220), but can be also moved in the opposite direction i.e. away from said immovable contact member (21) and against the force of said spring (222) when said switch member (4) is pivoted due to impact of the needle (32).

Inventors:
JANC, Domen (Cesta zmage 12, 1410 Zagorje Ob Savi, 1410, SI)
DRNOVSEK, Tadej (Loke 17, 1411 Izlake, 1411, SI)
DOLINSEK, Miran (Selo pri Zagorju 4, 1410 Zagorje Ob Savi, 1410, SI)
SKRABANJA, Janez (Vace 79, 1252 Vace, 1252, SI)
Application Number:
SI2018/000006
Publication Date:
October 18, 2018
Filing Date:
April 09, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
NELA RAZVOJNI CENTER ZA ELEKTROINDUSTRIJO IN ELEKTRONIKO, D.O.O. (Na Plavzu 79, 4228 Zelezniki, 4228, SI)
International Classes:
H01H71/52; H01H1/22; H01H71/40; H01H71/24; H01H73/50
Foreign References:
DE4424332A11996-01-18
DE3915127C11990-09-06
DE4122268A11993-01-14
Attorney, Agent or Firm:
BORSTAR, Dusan (Nova ulica 11, 1230 Domzale, 1230, SI)
Download PDF:
Claims:
PATENT CLAIMS

1. Security electric switch with improved contact assembly, said switch comprising

i) a box-like casing (1 ), which consists of electrically insulating material and is on its one terminal area furnished with a seat (1 1) enabling a detachable connection of said casing (1 ) with a standardized connecting ledge in each disposable electric switchboard, and on its another terminal area with a pivotal switch lever ( 12) serving both for manual activation of the switch due to establishing of an electric circuit there-through as well as for manual deactivation of the switch due to interruption of said electric circuit, wherein said casing (1) is moreover furnished with connecting terminals ( 13, 14), which are each per se connectable with each belonging electric conductor (15', 15"), via which said switch is integrated into each corresponding electric circuit;

ii) a contact assembly (2), which is integrated within said casing (1) and which consists of an immovable contact member (21 ) and of a movable contact member (22) and is adapted for establishing or interruption of the electric circuit through the switch, so that the electric circuit is established when said movable contact member (22) abuts said immovable contact member (21 ), and interrupted when said movable contact member (22) is maintained apart from said immovable contact member (21 ), wherein each of said contact members (21 , 22) is electrically connected with one of said contact terminals ( 13, 14) and herewith also with each belonging electric conductor (15', 15");

iii) an interrupting assembly (3), which is also integrated within said casing (1) and consists of a tubular casing (30), around which a coil (31 ) is wound, and within which a centrally arranged and longitudinally extending impact needle (32) is inserted, on the towards the contacting assembly (2) protruding end portion (30') of which a bimetallic membrane (33) is mounted, and in addition to that, a stationary yoke (34) and a longitudinally together with said needle (32) displaceable anchor (35) are inserted in the interior of said tubular casing (30) of said interrupting assembly (3) in the area of said coil (31 ), wherein a spring (36) is inserted between said yoke (34) and said anchor (35), which is intended to push the yoke (34) and the anchor (35) apart from each other, and wherein said needle (32) is displaceable along said casing (30) either by means of said bimetallic membrane (33) due to deformation thereof by overheating due to electric overloading, or by means of said anchor (35) whenever the last is moving relatively to the yoke (34) towards the contacting assembly (2) due to a magnetic field, which is by electric overloading generated by means of said coil (31 );

iv) a switching assembly (4), which consists of an electric insulating material and is on the one hand mechanically connected with said switch lever (12) on the casing ( 1) of the switch, so that by means of it said lever ( 12) is pivoted either to its first or to its second terminal position, and said switch assembly is arranged in front of said impact needle (32) of the interrupting assembly (3) and adjacent to said movable contact member (22) of the contacting assembly (2), so that by each displacement of said needle (32) towards said movable contact member (22) said needle (32) hits said switching assembly (4), which then causes that on the one hand said movable contact member (22) is moved apart from the immovable contact member (21 ), by which the electric circuit through the switch is interrupted, and on the other hand that said switch lever ( 12) is shifted from its first to its second end position, and wherein said switch assembly is held in its origin position by means of a spring (41 ), which is mounted within said casing (1 ) of the switch, characterized in that

said contact assembly (2) comprises an immovable contact member (21 ), which is made of an electric conductive material and is electrically connected with said coil (31 ) of the interrupting assembly (3), which coil is electrically connected with said first contacting terminal ( 13) on the casing ( 1) of the switch, by which said immovable contact member is arranged within said casing (1 ) outside of said interrupting assembly (3) and on that side, which is faced towards said seat (1 1 ), and wherein said contact assembly also comprises a movable contact member (22), which is also made of an electric conductive material and is inside of said casing ( 1 ) of the switch arranged adjacent to said immovable contact member (21 ) and is electrically connected with the other connecting terminal ( 14) on the casing (1 ) of the switch, wherein said movable contact member (22) is pivotally embedded within a cradle (220), which is formed on a free end portion of a cantilever beam (221 ) in the area in front of said needle (32) of said interrupting assembly (3) and is mechanically and electrically connected with said second connecting terminal ( 14), so that said movable contact member (22), which is pivotally embedded in said cradle (220), is pressed towards said immovable contact member (21 ) by means of a spring (222), by which it is supported in the adjacency of said cradle (220), but can be also moved in the opposite direction i.e. away from said immovable contact member (21 ) and against the force of said spring (222) when said switching assembly (4) is pivoted due to impact of the needle (32).

2. Switch according to Claim 1 , characterized in that said spring (22) is a flat spring.

3. Switch according to Claim 1 , characterized in that said spring (22) is a compression helical spring.

4. Switch according to anyone of Claims 1 to 3, characterized in that said spring (222) is on the one hand firmly attached to a bearing member (51 ) of an arc extinguishing ledge (5), which is mechanically and electrically connected with a connecting terminal ( 14) adjacent to said movable contact member (22), and on the other hand pivotally rest on said cradle (220) on said movable contact member (22).

5. Switch according to Claim 4, characterized in that said spring (222) is formed as cantilever and is mounted on a rigid and electrically conductive bearing member (51) on said ledge (5), which generally consists of an electrically insulating material, wherein said bearing member (51) is mechanically and electrically connected with the connecting terminal ( 14) on the side of the movable contact member (22), while the other bearing member (52) of said ledge (5) is also rigid and electrically conductive and is both electrically and also mechanically firmly connected with the immovable contact member (21 ).

Description:
Security electric switch with improved contact assembly

The present invention belongs to electricity, namely to basic electric components, in particular to switches and construction details of switches, which can be manipulated by means of corresponding lever, and in particular to switches suitable for protection against electric overloads. According to the International Patent Classification (IPC 9 ) such inventions belongs to the class H 01 H 71/52, H 01 H 73/50 or H OI H 71/40.

In this, the purpose of the invention is merely to simplify the security switch by simultaneously increasing its reliability. This means however, that appropriate concept of the security electric switch should be created, which would enable that upon integration of such switch into an electric circuit, as soon as either thermal overload or a short circuit current occur within said circuit, said switch would have to promptly and reliable interrupt the circuit by maintaining a contact resistance and internal power loss as low as possible, by which the velocity of pivoting the movable contact by interrupting of the circuit extending there-through should be as high as possible, so that also commutation of the electric arc should be quick, and on the other hand, also the mechanical concept and arrangement of the movable contact member and the immovable contact member should be simple and should allow automatized mass production and also such current path, which should on the one hand lead to deflection of the electric arc due to formation of appropriate magnetic field, and on the other hand also to maintaining of sufficient distance between the movable contact member and the immovable contact member, by which also discharging resistance of the switch in its interrupted state could be essentially improved.

Protective electric switch is disclosed in EP 2 545 576 B l , to the reference to which is herewith claimed by the applicant. Such switch comprises a casing, which consists of electric insulating material and is furnished with at least two electric contacts for attaching at least two wires, by means of which the switch can be integrated into each desired electric circuit. For the purposes of interconnecting or interrupting said electric circuit, a movable contact and a fixed contact are foreseen inside of said casing, which each per se consist of electric conductive material and are each per se connected to said contacts used for integration into each electric circuit. Said movable contact is adapted to cooperate with a disconnecting mechanism, which is joined with an actuating handle, which is adapted for controlling the switch and indicating errors, and can be activated by means of a trigger. Said trigger comprises at least an electric coil, a bimetallic washer and a needle, which may impact said disconnecting mechanism either due to thermal dilatation of said bimetallic washer or due to magnetic field generated by said coil. Said actuating handle is pivotally embedded in its pivot point within the casing and comprises an outside from the casing protruding portion and an inside of the casing located portion, to which an engaging clasp is attached, which serves for connecting the handle with said disconnecting mechanism and indirectly also with the movable contact. Said disconnecting mechanism comprises a disconnecting lever and an actuating lever, wherein the disconnecting lever is in its pivot point pivotally embedded within the casing and comprises a first seat, which is located in front of the needle of the trigger, and a second seat, which is located adjacent to the actuating handle and adapted to cooperate with the engaging clasp. A tooth is located between said seats at appropriate distance apart from the pivot point of said disconnecting lever, and a tension spring is attached to said tooth, which spring is on the other hand attached to the movable contact. The actuating lever, which is pivotally embedded in its pivot point on the disconnecting lever, comprises a first arm, which is located in front of said needle, as well as a second arm, which is located opposite with respect to said pivot point and adjacent to said second seat on the disconnecting lever. Consequently, the engaging clasp, which is on the one hand linked to the actuating handle, is insertable between the second arm of the actuating lever and the seat on the disconnecting lever.

In such switch the movable contact is conceived as an uniform lever, which is pivotally around its pivot point embedded within the casing and is allowed to be pivoted from its first stable position, in which it is rest onto the fixed contact, into its second stable position at certain distance apart from said fixed contact, and is moreover adapted to cooperate with the disconnecting mechanism, namely either with the disconnecting lever or with the actuating lever thereof. Moreover, said movable contact is adapted to be pressed towards the fixed contact by means of the spring, optionally a tension helical spring, which is tensioned between the tooth on the actuating lever and a seat, which is arranged on the movable contact at certain distance apart from the pivot point and at appropriate angle relatively to said arm. Said arm of the movable contact is furnished with a resting surface, which is intended for cooperation either with a seat of the disconnecting lever, which is located adjacent to the needle of the trigger, or with a protrusion on the first arm of the actuating lever. The pivot point of the movable contact is located at least approximately in the line of displacing said needle and in front of it, wherein the first arm of the actuating lever and the seat of the disconnecting lever are located within the area between the movable contact and the needle. Such switch is made of relatively complicated components, which are also produced and assembled in relatively a complicated manner, in particular in view of organization of mass production thereof. The switch as such generally allows interruption of the electric circuit in the case of overcurrent or short circuit current, but the path of the electric current is pretty inappropriate in the sense of generating each magnetic field, which shall preferably deflect the electric arc when the electric contacts members are moved towards each other or apart from each other. Moreover, some increasing of the velocity by moving the contact would also be desired, since this measure could lead to much higher discharging resistance of the switch in its interrupting state, in which the contact members are maintained apart from each other.

A similar switch is disclosed in EP 2 837 014 B l , to which also a reference is made.

Still further, a protective electric switch is also disclosed in WP 0 621 919 Al , which also comprises a casing with two connecting terminals, by which a movable and immovable contact member, which are located inside of said casing, are electrically connected. Such switch also comprises a thermal disconnecting unit, which is furnished with a coil, an electromagnet and a needle, and is integrated within the electric circuit between the immovable contact member and the belonging connecting terminal on the casing. The movable contact member is electrically connected with the belonging connecting terminal on the casing and can be shifted either into its first position, in which it abuts said immovable contact member, or into its second position, in which it is maintained at certain distance apart from said immovable contact member. Said movable contact member is on the other hand connected with actuating lever, which is pivotally around its pivot point embedded within said casing and comprises an outside of said casing protruding actuating arm, while on its inside of said casing located portion a clasp is attached, which is intended for establishing of interconnection between said lever and the interrupting mechanism. The interrupting mechanism consists of a switching lever and an actuating lever. Said movable contact member is pivotally embedded within said casing and is by means of a spring on the one hand held in a direction towards the casing and on the other hand pressed towards the immovable contact member. It is electrically connected with the belonging terminal on said casing by means of a flexible electric conductor, which is firmly, e.g. by soldering or welding, connected on the one hand with said immovable contact member and on the other hand with said terminal. Whenever an electric overload occurs, said interrupting mechanism by means of said needle triggers the actuating lever, which by means of the switching lever causes pivoting of the switching lever and at the same time also pivoting of the movable contact member apart from the immovable contact member and against the force of said spring, by which the electric circuit is interrupted. In this, the movable contact is shifted apart from the immovable contact member at a relatively small distance, which leads to relatively low discharging resistance of such switch. Regardless to that, by pivoting said movable contact also said flexible electric conductor is essentially deformed, which means that also both connection points, in which said conductor is connected to the connecting terminal and the movable contact manner, are exposed to undesired stresses, which leads to certain risk in view of reliability of such switch in particular during its long-term use, since at the properties of the applied materials may be at least locally and/or even chemically changed during the time, by which the number of connections and disconnections would generally even be increased. Besides, also in this case the path of the electric current is pretty inappropriate in the sense of deflecting the electric arc by means of the magnetic field generated by connecting or disconnecting said switch. The present invention refers to a security electric switch with improved contact assembly, wherein such switch generally comprises a box-like casing as well as a contact assembly, an interrupting assembly, a switching assembly and optionally also an arc extinguishing chamber, which are embedded within said casing.

Said box-like casing (consists of an electric insulating material and is on its one terminal area furnished with a seat, which enables a detachable connection of said casing with a standardized connecting ledge in each disposable electric switchboard, and on its another terminal area with a pivotal switch lever, which serves both for manual activation of the switch for the purposes of establishing of an electric circuit there-through as well as for manual deactivation of the switch due to interruption of said electric circuit. Said casing is moreover furnished with two connecting terminals, which are each per se connectable with each belonging electric conductor, via which said switch is integrated into each corresponding electric circuit.

The contact assembly is integrated within said casing and consists of an immovable contact member as well as of a movable contact member, which are both made of an electric conductive material. Said contact assembly is adapted for establishing or interruption of the electric circuit through the switch, so that the electric circuit is established when said movable contact member abuts said immovable contact member, or is interrupted, when said movable contact member is held apart from said immovable contact member. Each of said contact members is electrically connected with one of said contact terminals and herewith also with each belonging electric conductor. Said interrupting assembly is also integrated within said casing and consists of a tubular casing, around which a coil is wound, and within which a centrally arranged and longitudinally extending impact needle is inserted, on the towards the contacting assembly protruding end portion of which a bimetallic membrane is mounted. In addition, a stationary yoke and a longitudinally together with said needle displaceable anchor are inserted in the interior of said tubular casing of said interrupting assembly in the area of said coil, and a spring is inserted between said yoke and said anchor, which is intended to push the yoke and the anchor apart from each other. Consequently, said needle is displaceable along said casing either by means of said bimetallic membrane due to deformation thereof by overheating due to electric overloading, or by means of said anchor whenever the last is moving relatively to the yoke towards the contacting assembly due to magnetic field, which is by electric overloading generated in the area of said coil, or when it is returned back to its origin position due to the force generated by said spring.

The switching assembly generally consists of an electric insulating material and is on the one hand mechanically connected with said switch lever on the casing of the switch, so that by means of it said lever it can be pivoted either to its first its second terminal position, wherein said switch assembly is arranged in front of said impact needle of the interrupting assembly and adjacent to said movable contact member of the contact assembly. By each displacement of said needle towards the movable contact member, said needle hits the switching assembly, which then causes that on the one hand said movable contact member is moved apart from the immovable contact member, by which the electric circuit through the switch is interrupted, and on the other hand that said switch lever is simultaneously shifted from its first to its second terminal position, wherein said switching assembly is maintained in its origin position by means of a spring, which is mounted within said casing of the switch.

The present invention proposes a switch, in which said contact assembly comprises an immovable contact member, which is made of an electric conductive material and is electrically connected with said coil of the interrupting assembly, wherein said coil is electrically connected with said first contacting terminal on the casing of the switch, and said immovable contact member is arranged within said casing outside of said interrupting assembly and on that side thereof, which is faced towards said seat, and wherein said switch further comprises a movable contact member, which is also made of an electric conductive material and is inside of said casing of the switch arranged adjacent to said immovable contact member and is electrically connected with the other connecting terminal on the casing of the switch.

Said movable contact member is pivotally embedded within a cradle, which is formed on a free end portion of a cantilever beam in the area in front of said needle of said interrupting assembly and is mechanically and electrically connected with said second connecting terminal, so that said movable contact member, which is embedded in said cradle, is pressed towards said immovable contact member by means of a spring, by which it is supported in the adjacency of said cradle, and can also be moved in the opposite direction i.e. away from said immovable contact member and against the force of said spring when said switching assembly is pivoted due to impact of the needle.

Said spring, which is preferably a flat spring, or may optionally also be a compression helical spring, is in a preferred embodiment of the invention on the one hand firmly attached to a bearing member of an arc extinguishing ledge, which is mechanically and electrically connected with a connecting terminal adjacent to said movable contact member, and on the other hand pivotally rest on said cradle on said movable contact member. In this, said spring is formed as cantilever and is mounted on a rigid and electrically conductive bearing member on said ledge, which generally consists of an electrically insulating material, wherein said bearing member is mechanically and electrically connected with the connecting terminal on the side of the movable contact member, while the other bearing member of said ledge is also rigid and electrically conductive and is both electrically and also mechanically firmly connected with the immovable contact member.

The invention will be further described on the basis of an embodiment, which is presented in the attached drawings, in which

Fig. 1 is a schematically presented security electric switch according to the invention;

Fig. 2 is a schematically presented electric circuit through the switch according to Fig. 1 ;

Fig. 3 is a separately presented contacting assembly of the switch according to

Figs. 1 and 2 in isometric view;

Fig. 4 is a contacting assembly according to Fig. 3 when mounted within the switch according to Figs. 1 and 2 and in the state, in which the movable contact member abuts the immovable contact member;

Fig. 5 is the movable contact of the contacting assembly according to Fig. 3, in front view;

Fig. 6 is a contacting assembly according to Fig. 3 when mounted within the switch according to Figs. 1 and 2 and in the state, in which the movable contact member is held apart from the immovable contact member; Fig. 7 is a contacting assembly according to Fig. 3 when mounted within the switch according to Figs. 1 and 2 by moving the movable contact member apart of the immovable contact member:

Fig. 8 is a separately shown interrupting assembly of the switch according to the invention:

Fig. 9 is an interrupting assembly, presented without the coil and in a longitudinal cross-section along its diametrical plane;

Fig. 10 is an interrupting assembly together with said coil and presented in a

longitudinal cross-section along its diametrical plane in the case, when the electric current in the circuit slightly exceeds the nominal current value;

Fig. 1 1 is an interrupting assembly together with said coil and presented in a

longitudinal cross-section along its diametrical plane in the case, when the electric current in the circuit essentially exceeds the nominal current value.

A security electric switch (Figs. 1 and 2) comprises a box-like casing 1 as well as a contact assembly 2, an interrupting assembly 3, a switching assembly 4 and optionally also an arc extinguishing chamber 5, which are embedded within said casing 1.

Said box-like casing 1 consists of electrically insulating material and is on its one terminal area furnished with a seat 1 1 , which serves for establishing of a detachable connection of said casing 1 with a standardized connecting ledge in each disposable electric switchboard. The casing 1 is on its another terminal area furnished with a pivotal switch lever 12, which serves both for manual activation of the switch by means of establishing of an electric circuit there-through, or also as for manual deactivation of the switch due to interruption of said electric circuit Moreover, said casing 1 is furnished with connecting terminals 13, 14, which are each per se connectable with each belonging electric conductor 15', 15", via which said switch is integrated into each corresponding electric circuit;

Furthermore, a contact assembly 2 is integrated within said casing 1 and comprises an immovable contact member 21 as well as a movable contact member 22, and is adapted for establishing or interruption of the electric circuit through the switch, such that the electric circuit is established, when said movable contact member 22 abuts said immovable contact member 21 , or is interrupted, when said movable contact member 22 is maintained apart from said immovable contact member 21. Each of said contact members 21 , 22 is electrically connected with one of said contact terminals 13, 14 and herewith also with each belonging electric conductor 15', 15".

Still further, an interrupting assembly 3 is integrated within said casing 1 and consists of a tubular casing 30, around which a coil 31 is wound and which is separately shown in Figs. 8 - 1 1. Within said casing 30 a centrally arranged and longitudinally extending impact needle 32 is inserted, on the towards the contacting assembly 2 protruding end portion 30' of which a bimetallic membrane 33 is mounted. Besides, a stationary yoke 34 and an anchor 35, which is displaceable longitudinally together with said needle 32, are inserted in the interior of said tubular casing 30 of said interrupting assembly 3 in the area within said coil 31. A spring 36 is inserted between said yoke 34 and said anchor 35, and is intended to push the yoke 34 and the anchor 35 apart from each other, and is in the presented embodiment available as a compression helical spring.

Said needle 32 is displaceable along said casing 30 either by means of said bimetallic membrane 33 due to deformation thereof by overheating due to electric overloading, or by means of said anchor 35 whenever the last is moving relatively to the yoke 34 towards the contacting assembly 2 due to a magnetic field, which is by electric overloading generated by means of said coil 31. Electric circuit, which is established through said switch according to the invention, namely through the conductors 15, 15 " and connecting terminals 13, 14, the movable contact member 22 and immovable contact member 21 as well as the interrupting assembly 3, during the regular operation of the switch maintains the regular situation, which is presented in Fig. 1. As soon as the electric circuit is increased above the nominal value, the coil 31 and the casing 30 are heated, and the heat is transferred to the bimetallic membrane 33, which in such situation deflects towards the right according to Fig. 1 , namely towards the contacting assembly 2, by which simultaneously also the needle 32 is shifted in the said direction. As soon as the short circuit current occurs, the current essentially exceeds the nominal value in a very short time period, so that there a lack of time for transferring the heat towards the bimetallic membrane 33. In such case appropriate magnetic field is generated within the coil 31 promptly upon increasing the current, which results in immediate movement of the anchor 35 towards the yoke 34 against the retaining force of said spring 36, which also results in immediate movement of said needle 32 towards the contact assembly 2.

A switching assembly 4 generally consists of an electric insulating material and is on the one hand mechanically connected with said switch lever 12 on the casing 1 of the switch, so that on the one hand by means of it said lever 12 is pivoted either to its first or to its second terminal position, and on the other hand, said switch assembly is arranged in front of said impact needle 32 of the interrupting assembly 3 and adjacent to said movable contact member 22 of the contacting assembly 2. Said switching assembly 4 is held in its initial position according to Fig. 6 by means of a spring 41 , which is attached to the casing 1 of the switch.

By each displacement of said needle 32 towards said movable contact member 22 due to previously described reasons, said needle 32 hits said switching assembly 4, which then causes that on the one hand said movable contact member 22 is moved apart from the immovable contact member 21 (Fig. 7), by which the electric circuit through the switch is interrupted (Fig. 6), and on the other hand that said switch lever 12 is shifted from its first to its second end position.

Upon interruption of the electric circuit through the switch, by pivoting said lever 12 back to its initial position the switching assembly is returned back to its initial position, by which the movable contact member 22 is returned back to its initial position in which it is rest on the immovable contact member 21 of the contacting assembly 2.

As mentioned, said contact assembly 2 comprises an immovable contact member 21 and a movable contact member 22. The immovable contact member 21 is made of an electric conductive material and is electrically connected with said coil 31 of the interrupting assembly 3, and the coil 31 is electrically connected with said first contacting terminal 13 on the casing 1 of the switch. The immovable contact member is arranged within said casing 1 outside of said interrupting assembly 3 and on that side, which is faced towards said seat 1 1. Said movable contact member 22 is also made of an electric conductive material and is inside of said casing 1 of the switch arranged adjacent to said immovable contact member 21 and is moreover electrically connected with the other connecting terminal 14 on the casing 1 of the switch. In the sense of resolving the previously defined technical problem, the switch according to the invention is characterized in that said movable contact member 22 is pivotally embedded within a cradle 220, which is formed on a free end portion of a cantilever beam 221 in the area in front of said needle 32 of said interrupting assembly 3 and is mechanically and electrically connected with said second connecting terminal 14. In this, said movable contact member 22, which is pivotally embedded in said cradle 220, is pressed towards said immovable contact member 21 by means of a spring 222, by which it is supported in the adjacency of said cradle 220, but can be also moved in the opposite direction i.e. away from said immovable contact member 21 and against the force of said spring 222 when said switch member 4 is pivoted due to impact of the needle 32.

In the shown embodiment (Fig. 3) said spring 22 is designed as a flat spring, although also a not-shown embodiment provides that said spring 222 can also be a compression helical spring.

Still further, in the shown embodiment said spring 222 is on the one hand firmly attached to a bearing member 51 of an arc extinguishing ledge 5, which is mechanically and electrically connected with a connecting terminal 14 adjacent to said movable contact member 22, and on the other hand pivotally rest on said cradle 220 on said movable contact member 22. In this, said spring 222 is formed as cantilever and is mounted on a rigid and electrically conductive bearing member 51 on said ledge 5, which generally consists of an electrically insulating material. In this embodiment, said bearing member 5 1 is mechanically and electrically connected with the connecting terminal 14 on the side of the movable contact member 22, while the other rigid and electrically conductive bearing member 52 of said ledge 5 is electrically and mechanically firmly connected with the immovable contact member 21.

Thanks to such described embodiment of the movable contact member 22 and the concept of supporting thereof by means of the spring 222, when said movable contact member 22 is rest on the immovable contact member 21 , the component F k i of the force F v i of the spring 222 is actually the force, by which said movable contact member 22 is pressed towards the immovable contact member 21 and a component, by which the movable contact 22 is maintained in its position (Fig. 4 and 5). Said component F^i acts on the moment arm r k] relative to the pivot point on the cradle 222, while the force F v) is acting on the moment arm r v) . Torques produced by F k i and F v) are equal. When the contact member 22 (Fig. 7) is moved, direction of force F V | is changed, and the moment arm r V | is reduced to r v2 .

Functioning of the switch both by energizing with nominal electric current and also with excessive electric current has already been explained, and the previously defined technical problem is herewith resolved.