US3859486A

US3859486A - Electric vacuum switching unit having a power drive

Info

Publication number: US3859486A
Application number: US291931A
Authority: US
Inventors: Kurt Haese; Wolfgang Frewe; Hans-Jurgen Lendt
Original assignee: Siemens Corp
Current assignee: Siemens AG; Siemens Corp
Priority date: 1971-09-30
Filing date: 1972-09-25
Publication date: 1975-01-07
Anticipated expiration: 1992-01-07
Also published as: GB1401646A; FR2154515A1; DE2149437B2; CA977015A; CH551687A; DE2149437A1; SE373227B; JPS4843168A; JPS5244432B2; FR2154515B1; DE2149437C3

Abstract

An electric vacuum switching device having a power drive acting on the actuator rod of a vacuum switch by means of a lever is disclosed. According to the invention, the lever is connected at one end with the power drive and, at a bearing surface situated between its ends, with the actuator rod of the vacuum switch. The other end of the lever is supported in a device which permits shifting the fulcrum by an amount corresponding to the switching stroke of the vacuum switch.

Description

United States Patent 1191 1111 3,859,486 Haese et al. Jan. 7, 1975 [5 1 ELECTRIC VACUUM SWITCHING UNIT 2,873,332 2/1959 Williams ZOO/I66 M HAVING A POWER DRIVE FOREIGN PATENTS OR APPLICATIONS [75] Inventors: Kurt Haese; Wolfgang Frewe; o

H J g dt, a o Berlin Japan -00/l44 B Germany Primary ExaminerRobert S. Macon f [73] Asslgnee ggmg t Mumch Attorney, Agent, or Firm-Kenyon & Kenyon Re1lly Carr & Chapin [22] Filed: Sept. 25, 1972 [21] Appl. No.: 291,931

[57] ABSTRACT [30] Foreign Application Priority Data An electric vacuum switching device having a power Sept. 30, 1971 Germany 2149437 drive acting on actuator rod of a vacuum Switch y means of a lever is disclosed. According to the inven- [52] U.S. Cl. 200/144 B, 200/286 tion, the lever is connected at ne end with the power [51] Int. Cl. ..H01h 33/66 drive at a a ng surfa e situated between its 8] F eld Of Search 200/144 B, 166 M; 335/273, ends, with the actuator rod of the vacuum switch. The 335 275 17 other end of the lever is supported in a device which permits shifting the fulcrum by an amount correspond- [56] References Cit d ing to the switching stroke of the vacuum switch. UNITED STATES PATENTS 2,849,185 8/1958 Keyes 200/166 M 8 Clams 3 Drawmg F'gures I M .I\-' 1 l0 /au;a-;= 32

\n -22. m N

Patented Jan. 7, 1975 2 Sheets-Sheet 1 Fig.1

Patented Jan. 7, 1975 2 TSheets-Sheet 2.

Fig.3

ELECTRIC VACUUM SWITCHING UNIT HAVING A POWER DRIVE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is concerned with electric vacuum switching gear, and more particularly with switches having a power drive and a voltage of l to lkV.

2. Description of the Prior Art A previously known design for vacuum switching units is one in which the contacts are closed by the influence of atmospheric pressure. If such switching units are integrated into switching gear having power drives, an auxiliary force is required to keep the contacts open, in order that the power drive operates in the customary direction of operation. The power drive, for example, an electromagnet, when excited overcomes the auxiliary force so that the vacuum switch is switched on by atmospheric pressure.

SUMMARY OF THE INVENTION This invention is concerned with the design of the power transmission between the power drive and the vacuum switch of vacuum switching devices, and more particularly with vacuum contactors. The transmission mechanism is to be designed so that the vacuum switch can be replaced and adjusted in a simple manner. The

. replacement of the vacuum switch must be done when switch, particularly a vacuum contactor, comprising a power drive acting by means of lever on the actuator rod of a vacuum switch. The invention consists of connecting the lever at its one end with the power drive and with the actuator rod at a bearing surface situated between its ends. The other end of the lever is supported in a device permitting the shifting of the fulcrum by an amount corrsponding to the switching stroke of the vacuum switch. This arrangement, first, meets the requirements regarding the interrelation between the forces and displacements of the power drive and the vacuum switch. Because the connection point between the actuator rod and the lever is situated between the ends of the lever, a reduction in the motion of the power drive is obtained. This makes it possible to fit the relatively small switching stroke of the vacuum switch, which maybe in the order of a few millimeters, to the larger operating stroke of the power drives, for example, electromagnetic systems.

Through this invention the vacuum switch can be adjusted in a simple manner, and at a readily accessible location. This high accessibility is achieved because the fulcrum of the lever, which acts as a fixed bearing, is used for the adjustment. This fulcrum is close to the vacuum switch, i.e., in a readily accessible part of the switch. The alignment of a vacuum switch is accomplished after the switch is placed in the unit and the mechanical connection between the actuator rod and the lever is made. The adjustment is made by loosening and shifting the fulcrum of the lever by the permissible amount in the direction of the switching stroke of the vacuum switch. The switch is then secured and the operating position of the fulcrum of the lever is reestablished. The vacuum switch is then in the off position.

The invention can be further developed in several other ways to simplify the adjustment of the vacuum switch. In particular, the vacuum switch can be held and secured in a clamping device at the end away from the actuator rod so that it is movable in the direction of the switching stroke. Advantageously, the vacuum switch can be connected by the clamping device with its terminal post. This then simultaneously forms the electrical connection with one of the terminals of the switch.

The above-mentioned device for supporting the lever may comprise a fulcrum pin which is displaceable in a recess of a stationary part of the housing of the vacuum switching unit by an amount corresponding to the switching stroke and secured in the operating position. Here the recess limits the displacement of the fulcrum pin, thereby assuring that the vacuum switch or switch vessel occupies the correct position relative to the power drive.

A sample design solution for securing the pivot pin is obtained by means of threaded studs. The latter may have a conically pointed end and a diameter such that the tip can engage below the longitudinal axis of the displaced fulcrum pin. The fulcrum pin can then be put in its operating position merely by screwing in the threaded studs.

The above-mentioned recesses in a stationary portion of the vacuum switching unit may be graduated in the direction of the switching stroke. This graduation can be implemented, for example, by reducing the dimension of the longitudinal direction of the fulcrum pin. By this method, a step is formed in the recess, so that, for example, a fulcrum pin of smaller length can be displaced by the larger dimension of the recess, but a fulcrum pin of greater length can only be displaced up to the step. In this manner the device also can be used with a vacuum switch having a different switching stroke. Particularly reliable interaction between the fulcrum pin and the graded recess can be achieved by using either a fulcrum pin with constant diameter or a pivot pin whose diameter is reduced or enlarged at its end. Depending on the enlargement or reduction of the diameter at the end, one obtains a displacement of different size compared to the pivot pin of uniform diameter.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in further detail in the following drawings with reference to the example of an embodiment shown in the Figures.

FIG. 1 illustrates a cross-sectional view of a vacuum contactor;

FIGS. 2 and 3 illustrate details of the device for adjusting the switching units.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 a sheet steel frame 1 containing a magnetic system 2 is shown schematically. The stationary part 3 carries an exciter. coil 4. The movable portion 5 through rod 6 drives a lever 7 which engages rod 6 at its forked end. At its opposite end, the lever 7 is supported on a fulcrum pin 10, as described below. Be cause the contactor with the frame 1 is mounted on a vertical support, the fulcrum pin is situated on the readily accessible side of the contactor.

At about two-thirds of the length from the rod 6, the lever 7 has a shoulder 11 which forms a support surface for a pin 12 inserted into the actuator rod 13 of a vacuum switch 14. The lever 7 can be designed in the shape of a fork, so that the pin 12 is supported at both its ends. For installation, the vacuum switch 14 can be hung in the lever 7 by its pin 12.

The vacuum switch 14 is located within a chamber of insulating material 15, open to the right of FIG. 1. From this chamber of insulating

material connecting bars

16 and 17 protrude at the top and bottom. The connecting bar 16 is connected with the currentcarrying actuator rod 13 of the vacuum switch 14 by means of a flexible conductor 21 which may be made, for example, from a' braided copper strip. A clamp 20 is located around the actuator rod 13. At the lower end of the vacuum switch 14, a similar arrangement is provided, but here a clamping device 22 together witha clamping screw 23 for the terminal post 24 provides the simultaneous electrical connection and the mechanical mounting of the vacuum switch. The clamping device 22 is directly connected with the connecting bar 17.

Details of the support for lever -7 will now be explained with the aid of FIG. 2, showing in a perspective view the open end of the insulating chamber and the end 8 of the lever 7, accessible at that point. The fulcrum pin 10, which passes through lever 7, engages in recesses 26 with its overhanging ends 25. The recesses 26 are situated in the sidewalls 27 of the insulated chamber 15. The recesses are covered by cover plates 28, which are fastened to the side walls 27 by means of two screws 30 on each side. As shown in FIG. 2, the cover plates 28 are-each provided with a threaded hole 31 for a threaded stud 32 which, with its end, supports fulcrum pin 10 in its operating position in such a manner that no play is left between the fulcrum pin and the upper end of the recess 26.

The vacuum contactor described can be made with several poles. To this end two or more insulatingmaterial chambers with vacuum switches can be arranged side byside. The drive can be effected by a common magnet system and individual levers 7.

If a vacuum switch, located in the insulating-material chamber 15, is to be adjusted, the clamping screw 23 is loosened and the threaded studs 32 are screwed out so that the fulcrum pin 10 is no longer supported. Then the end of the lever 7 is pushed down so that the fulcrum pin 10 comes to rest at the lower end of the recesses 26. The distance a shown in FIG. 3 travelled by the fulcrum pin 10 in this operation corresponds to the switching stroke that the actuator rod 13 must travel. After pressing down the end of the lever, the vacuum switch 14 is secured by tightening the clamping screw 23. Subsequently the end of the lever 7 is lifted again and the threaded studs 32 are screwed in, so that the position of the parts shown in FIG. 2 is obtained. The correct relation between the drive motion and the switching stroke of the vacuum switch 14 is thereby established. The contacts of the vacuum switch are then open by the amount provided.

In designing the recess 26 it must be noted that the necessary movement of the lever 7 which must be made to adjust the vacuum switch 14, the point of engagement of the lever at the rod 6 acts as the fulcrum. The switching stroke is therefore translated according to the physics of leverage. The recess 26 furthermore must be longer than the diameter of the pivot pin, so that the desired switching stroke is obtained.

In order to facilitate the lifting of the lever end 8, which must be lifted against the force exerted by the atmospheric pressure on the movable contact of the vacuum switch, the ends of the threaded studs 32 are conically pointed. If the tip 33 of the clamping screws 23 is below the longitudinal axis of the pivot pin 10, the latter is moved automatically .into the operating position when the threaded studs are tightened according to the wedge principle.

Through a special design of the recesses 26 the same simple adjustment is obtained for vacuum switches of different switching strokes. As shown in FIG. 3 the recess 26 has a step 34, so that the fulcrum pin can only be displaced to this step. Thus for adjusting a vacuum switch having a smaller stroke the necessary travel is limited. If a vacuum switch with a longer switching stroke is to be used, a fulcrum pin 10 may be used having a diameter at its end reduced to a pivot 35. A longer travel stroke is thereby obtained. The arrangement can also logically be extended to three or more different switching strokes. It is also possible to obtain adjustment for different switching strokes by means of fulcrum pins whose diameters are increased at the ends. In any event, the end of the recess 26 which corresponds to the operating position of the fulcrum pin must be designed so that the pivot axis is retained regardless of the shape of the ends of the fulcrum bearings.

As mentioned above, an auxiliary force is active in the vacuum contactor, which keeps the switch vessels in the open condition. This auxiliary force can be suppliedby tension or compression springs, which, for exampIeIEngage at the armature 5 and keep the latter together with the rod 6 in the position shown in FIG. 1.

In the foregoing, the invention has been described in reference to specific exemplary embodiments. It will be evident, however, that variations and modifications, as well as the substitution of equivalent constructions and arrangements for those shown for illustration, may be made without departing from the broader scope and spirit of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in a illustrative rather than in a restrictive sense.

What is claimed is:

1. An electric vacuum switching device having a replaceable and adjustable vacuum switch and a power drive connected to an actuator rod of the vacuum switch, the improvement comprising a lever having a longitudinal axis and being connected at one end to the power drive, said lever having a supporting, pivoting surface positioned between its two ends, the actuator rod of the vacuum switch being connected to the lever ing member for securing said switch at its end opposite to the connection between the actuator rod of the switch and the lever, said clamping member permitting movement of the switch only in the direction of the switching stroke.

3. An electric vacuum switching device having a replaceable and adjustable vacuum switch mounted in a stationary housing and having a power drive connected to an actuator rod of the vacuum switch, the improvement comprising: a lever connected at one end thereof to the power drive, said lever having a supporting, pivoting surface positioned between its two ends, the actuator rod of the vacuum switch being connected to the lever at said supporting surface; and, a supporting arrangement for pivotally supporting the lever at its other end so as to define the fulcrum thereof, said arrangement including a fulcrum pin at said other end of said lever for defining said fulcrum; and means for adjusting the lever so as to displace the fulcrum by an amount corresponding to the stroke of the vacuum switch whereby the vacuum switch can be adjusted so that said stroke is adapted to the stroke of the power drive; said means including recess means formed in the stationary housing of the switching device for receiving said fulcrum pin so as to be displaceable therein a distance corresponding to said stroke of the vacuum switch; and, removable holding means for pivotally holding said fulcrum pin at a determined position in said recess means when said switching unit is in service.

4. An electric vacuum switching device as in claim 3, said removable holding means comprising threaded studs for supporting said fulcrum pin at its ends in said determined position.

5. An electric vacuum switching device as in claim 4 in which the threaded studs are conically tipped.

6. An electric vacuum switching device as in claim 4, said recess means being a stepped recess permitting the adjustment of the fulcrum pin for varying vacuum switch strokes.

7. An electric vacuum switching device as in claim 4 in which the diameter of the fulcrum pin is reduced at the end within the recess permitting the use of the fulcrum pin for a vacuum switch having a long switching stroke.

8. An electric vacuum switching device as in claim 4 in which the diameter of the fulcrum pin is enlarged at the end within the recess permitting the use of the fulcrum pin for a vacuum switch having a short switching stroke.

Claims

1. An electric vacuum switching device having a replaceable and adjustable vacuum switch and a power drive connected to an actuator rod of the vacuum switch, the improvement comprising a lever having a longitudinal axis and being connected at one end to the power drive, said lever having a supporting, pivoting surface positioned between its two ends, the actuator rod of the vacuum switch being connected to the lever at the supporting surface; and, a supporting arrangement for pivotally supporting the lever at its other end so as to define the fulcrum thereof, said arrangement including means for adjusting the lever so as to displace the fulcrum in a direction transverse to said longitudinal axis by an amount corresponding to the stroke of the vacuum switch whereby the vacuum switch can be adjusted so that said stroke is adapted to the stroke of the power drive.

2. An electric vacuum switching device as in claim 1 in which the vacuum switch further comprises a clamping member for securing said switch at its end opposite to the connection between the actuator rod of the switch and the lever, said clamping member permitting movement of the switch only in the direction of the switching stroke.