Abstract:
An electrical switchgear includes a thermal trip, an electromagnetic trip, and a switching mechanism with a latching point and at least one contact point that is continuously opened or closed. An operating handle is connected to one end of a lug by means of a coupling element and the other end of the lug is coupled to a contact base that carries a moving contact member. The thermal trip is coupled to a trip lever by a connecting rod that passes over the contact base so that both the thermal trip and the electromagnetic trip open a latching point in the event of an excess current and/or short circuit current.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. §119 to German Application No. 10 2005 041 232.7 filed in Germany on 31 Aug. 2005, the entire contents of which is hereby incorporated by reference in its entirety. 
   BACKGROUND 
   An electrical switchgear is disclosed. 
   In particular, a line circuit breaker is disclosed which is used for disconnecting loads in the event of a short circuit or excess current. Such a breaker can be used in combination with, for example, motor circuit breakers and fault-current circuit breakers. 
   A line circuit breaker has in its interior an electromagnetic trip which has a plunger-type electromagnet, with a core and a moving armature around which a coil is wound. In the case of a short circuit, the armature moves and, on the one hand, impacts the contact lever so that the contact point is rapidly opened; on the other hand, it also effects a continuing opening of the contact point via a latch. The thermal trip which is constructed as a bimetallic trip in most cases exclusively acts on the latch to effect the continuing opening of the contact point. The bimetal is constructed in most cases as a strip which bends out due to the different coefficients of expansion of the metals joined to one another. Naturally, a strip of a shaped memory alloy can also be used instead of a thermal bimetal. 
   In the switch S2 of the company ABB Stotz Kontakt GmbH, Heidelberg, the latch is supported between two boards which are connected to one another and which also form or accommodate the bearing point for the corresponding components forming the latching point. In this switch, the electromagnetic trip is located between the thermal bimetal and the contact lever. 
   SUMMARY 
   A switch is disclosed which can, for example, considerably simplify the assembly and to improve the sequence of movements of the components of the latch. 
   An exemplary contact base constructed as contact lever is located between the thermal and the electromagnetic trip; together with a trip lever supported rotatably and interacting with the electromagnetic trip, the latch lever forms the latching point, the thermal trip being coupled to the trip lever by means of a rod passing over the contact base so that both the thermal trip and the electromagnetic trip open the latching point via the trip lever in the event of an excess current and/or short circuit current. 
   An exemplary embodiment can considerably improve the alignment between unlatching and impact of the contact lever before the impact of the contact lever because the chain of tolerance is considerably shortened compared with the above-mentioned switch S2. The striker pin hits the trip lever and the latter moves up to unlatching, where it meets the moving contact lever for opening it. 
   An advantageous embodiment can have the aim that the trip lever is rotatably supported between the axis of rotation of the operating handle and the electromagnetic trip, the trip lever being constructed as two-armed lever, the first arm of which, together with the latch lever, forms the latching point and the second arm of which interacts with the thermal trip and the electromagnetic trip. 
   According to a further embodiment, the first lever arm of the trip lever, in the on position, extends approximately perpendicularly to the front wall of the switchgear or approximately perpendicularly to the center axis of the electromagnetic trip, whereas the second lever arm has a first section extending perpendicularly to the first arm and an adjoining second section which covers the striker pin of the electromagnetic trip. 
   According to an advantageous embodiment, the axis of rotation of the trip lever is located stationary on a line which is formed by the bearing points of the trip lever and of the operating handle, this line extending approximately perpendicularly to the plane of mounting or, respectively, to the front wall. 
   According to a further embodiment, a spring arrangement is provided which can permanently load the trip lever in such a manner that it moves the striker armature of the electromagnet system into its ready-to-trip position at the end of tripping, as a result of which the latching point is latched again and the switchgear can be switched on again. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention and other advantageous embodiments and improvements of the invention and further advantages will be explained and described in greater detail with reference to the drawing, in which an illustrative embodiment is shown and in which: 
       FIG. 1  shows a partial view into an exemplary switchgear in the off position; 
       FIG. 2  shows a partial view corresponding to  FIG. 1 , in the on position; 
       FIGS. 3 and 4  show a view which corresponds to the view of the switchgear shown in  FIGS. 1 and 2 , at the beginning of tripping and at the end of tripping. 
   

   DETAILED DESCRIPTION 
   Reference will be made to  FIG. 2 . 
   A line circuit breaker  10  which is partially shown in the area of its switching mechanism has a housing  11  which is composed of a shell-shaped lower housing part and a shell-shaped upper housing part. In the view of  FIGS. 1 to 4 , only the lower housing part can be seen. 
   The housing is constructed in pedestal construction and has a front front wall  12 , two rear front walls  13  and  14  which are not shown completely in the drawing, two front narrow side walls  15  and  16  which connect the front front wall  12  with the rear front walls; and parallel with the front front wall and the rear front walls  13 ,  14 , respectively, a mounting wall closing off the housing towards the bottom, is located which is not shown in  FIGS. 1 to 4 . 
   The front front wall  12  has an approximately semicircular bump  17 , in the area of which a switch handle  19  is supported on a bearing  18 . The switch handle  19  is a two-armed lever with an operating handle  20  and an eye-shaped continuation  21  located in the interior of the switchgear; in the eye-shaped continuation  21 , a through opening  22  is located; the center point of the through opening  22 , the center point of the bearing  18  and the center line of the operating handle  20  are located on one line or, respectively, aligned with one another. 
   The operating handle  20  protrudes from an opening  23  in the bump or protrusion  17 . 
   In the through opening  22 , a leg (not shown) of a bow  24  is inserted which has a U-shape, the web  25  of the bow being visible in  FIGS. 1 to 4 . The other leg of the U-shaped bow  24  engages in a penetration  26  of a lug  27  and an elongated hole  28  of a latch lever  29  and is guided therein. The latch lever  29  has a locking nose  30  which, together with a recess  31  at a striker lever  32 , forms a latch. Accordingly, the latching point is designated by the reference numbers  30 / 31  in the text which follows. The other end of the lug  27  is connected by means of an articulated axle  33  in an articulated manner with a contact lever  34  which exhibits approximately in its center an elongated hole  35  by means of which it is supported rotatably in the housing  11  at a stationary pin  36 . As a result, the contact lever  35  becomes a two-armed lever, the lever  37  located oppositely to the bearing point  33  carries the so-called moving contact member  38  which interacts with a stationary contact member  39 . The latch lever  29  is rotatably supported in the housing (both in the lower housing part and in the upper housing part) at its end located oppositely to the latching point  30 ,  31  via a pin arrangement  40 . 
   The arrangement is made in such a manner that the lug  27  and the latch lever  29  are approximately in a line. In the on position, in which the nose  30  rests against the recess  31 , the latch is in the on position, that is to say when the moving contact member  38  touches the stationary contact member  39  in a first stable position in which the center axis of the web  25  passes laterally, on the left in the embodiment according to  FIG. 2 , next to the center axis of the bearing or the rotary bearing  18  of the switch handle  19  so that the center axis of the leg  25  forms an obtuse angle opened in the direction of the latching point  30 / 31  with the line formed by the center axis of the opening  22  and the center axis of the bearing  18 . The lug  27  and the latch lever  29  are approximately parallel to the front front wall. In the on position, the bow  24  presses the lug away from the latching point  30 / 31  so that the force arising as a result produces the switching-on force. The elongated hole  35  lies with its end which is located on the side of the contact lever  34  on which the moving contact member is located. The elongated hole  35  extends approximately perpendicularly to the longitudinal extent of the contact lever  34 . 
   The striker lever or trip lever  32  can be swiveled about a stationary axle  41  below the operating handle or its bearing point at  18 . It has a first lever arm  42  at which the recess  31  is molded on; in its on position, this first lever arm  42  extends perpendicularly or approximately perpendicularly to the front wall. The striker lever  32  also has a second lever arm  43  which has a first section  44  and a second section  45  which adjoins the first section  44  and protrudes approximately towards the mounting side, that is away from the front side  12 . 
   The switchgear has an electromagnetic trip  46 , the striker armature  47  of which extends parallel to the front wall or to the mounting wall, respectively, and the end  48  of which protruding from the trip  46  is covered by the section  45 . 
   At the free end of the section  45 , an end  49  of a connecting rod  50  is connected and hereby articulated, which engages behind a thermal bimetallic strip  52  which is the thermal trip, by means of a pin  51  which protrudes perpendicularly to the plane of the drawing into the latter and, therefore, is only shown dashed. The thermal trip  52  is thus located between the pin  51  and the section  45 . 
   The longitudinal axis of the connecting rod  50  extends approximately perpendicularly to the longitudinal extent of the thermal bimetal; in the embodiment according to  FIGS. 1 to 4 , the longitudinal extent of the thermal bimetal  52  forms, together with the mounting side, an acute angle which is open towards the electromagnetic trip. 
   Between the left-hand narrow side wall  15 , that is to say the wall which is adjacent to the hinge  33  and the contact lever in the area between the hinge point  33  and the elongated hole  35 , a compression spring  53  is provided which loads the contact lever clockwise around the bearing point  36  so that the compression spring  53  supports the off movement, that is to say the movement of the contact lever  34  out of the position according to  FIG. 2  into the position according to  FIG. 1 . 
   If then the striker armature  48 , due to a short circuit current, is moving in the direction of the arrow P, it presses on the section  45  and, in doing so, swivels the striker lever clockwise around the axis of rotation  41  as a result of which the latching point  30 / 31  is unlatched, see  FIG. 3 , so that the latch lever  29  can swivel clockwise around its axis. In doing so, the leg of the bow  24  accommodated in the opening  26  of the lug  27  slides in the elongated hole  28  until it has reached the opposite, left-hand (in  FIGS. 1 to 4 ) end of the elongated hole  28 . This releases the force of the spring  53 ; the end of the elongated hole  35  located opposite to the contact point  30 ,  31  comes to rest against the stationary pin  36  so that the compression spring  53  can also swivel the contact lever  34  anticlockwise; as a result, the contact lever reaches its off position which has been reached at the end of tripping. The operating handle or switch handle  19  is released and can rotate counter clockwise around the axis  18  into the off position. During this process, the bow  24  releases or pulls it into the off position shown in  FIG. 1  in which it passes with its nose  30  back behind the recess  31  of the striker lever. The switch can now be switched on again by moving the operating handle  19  clockwise out of its off position into the on position shown in  FIG. 2 . 
   If the thermal trip  52  bends with an excess current, the free end bends approximately in the direction of the arrow P and, in doing so, takes along section  45  of the striker lever via the rod or connecting rod  15  as a result of which the recess  31  moves away from the nose  30  and, as a result, the latching point is opened. The beginning of tripping is again shown in  FIG. 3 , the further sequence is the same as that described above. 
   Naturally, the latch described by means of a line circuit breaker can also be used in a fault-current circuit breaker; in this case, a trip responding to a fault current would have to be used instead of the electromagnetic trip  46  which responds to short circuit current. 
   Naturally, the possibility also exists to use the latch for a motor circuit breaker in which, instead of a contact lever, a contact base is provided which carries a contact bridge which electrically conductively connects two stationary contact members, that is to say a pair of contact members, in the on state. 
   Reference will be made to  FIG. 1 . 
   The section  45  which extends perpendicularly to the first arm  42  continues past its bearing point  41  into a continuation (i.e., first section  44 ) which exhibits an angle bend, not shown in  FIGS. 1 to 4 , which protrudes into the plane of the drawing perpendicularly to the plane of the drawing. Around a protrusion  62 , extending concentrically with respect to the bearing point  41  and which is moulded on at the inside face  11   a  of the housing  11  and protrudes towards the observer, a spring  63  is wound, one arm of which (not shown) is held stationary in the housing and the other spring arm  64  of which presses resiliently against the protrusion  60  so that this spring continuously loads the striker lever or trip lever anticlockwise in the direction of pressing back the striker pin  47  or the armature  47 , respectively. This spring has the effect that the striker lever is pressed into its ready-to-latch position so that the latch lever, during its movement into the off position, see above, interacts with the first arm  42  of the trip lever, forming the latching point. 
   It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.