SK122896A3 - Device for tensioning the cut-in spring in actuator units for circuit breakers - Google Patents

Abstract

The invention concerns a device for tensioning the cut-in spring in actuator units for circuit breakers, in particular vacuum circuit breaker, the cut-in spring (7) being designed as a tensioning spring which is in contact with a cam (2) mounted on the cut-in shaft (5) and which can be tensioned both by an electric motor (20) and by a hand-turned shaft (21) through a spur-gear train, the last spur gearwheel (1) also being mounted on the cut-in shaft (5). The aim of the invention is to design a tensioning device in which the spur-gear train operates without overrunning, and reversing of the cam (2) is prevented or limited by the cut-in spring (7). This is achieved by virtue of the fact that the last spur gearwheel (1) in the spur-gear train is disposed over an overrunning bearing (6) on the cut-in shaft (5) in such a way that, when cut-in spring tensioning begins, the cam (2) and hence also the cut-in shaft (5), are carried directly by the last spur gearwheel (1) out of a position in which they are located past the bottom dead centre position (9) of the shaft (5) as the cam (2) rotates upwards, while, during the cut-in phase, the last spur gearwheel (1) is locked in position, when the cut-in shaft (5) turns through bottom dead centre (9), by the overrunning bearing (6) and by the operative connection with the other spur gearwheels in the spur-gear train.

Description

Apparatus for tensioning the closing spring of electric power switch actuating devices, in particular vacuum switches, in which the closing spring (7), designed as a tension spring, is connected to an eccentric (2) arranged on the closing shaft (5) and thus tensioned by an electric motor ( 20), as well as by means of a manual pulling shaft (21), by means of a spur gear, the last spur gear (1) of which is also arranged on the closing shaft (5). The solution is a device in which the spur gear operates without idling and the reverse rotation of the eccentric (2) is prevented or limited. This is achieved by arranging the last spur gear (1) of the spur gear on the starter shaft (5) by means of a freewheel bearing (6) such that the eccentric (2) and thus the starter shaft are at the beginning of the tensioning of the starter spring (7). (5), by the last spur gear (1) immediately carried away from the position behind the lower dead center (9) in the direction of rotation of the eccentric (2), while in the engaging phase when turning the closing shaft (5) through its lower dead center (9) the last spur gear (1) is locked in position by both the freewheel bearing (6) and due to a functional connection with the other spur gears.

PI / WEquipment for tensioning the closing spring of electric power switch control devices, especially vacuum switches

Technical field

BACKGROUND OF THE INVENTION The invention relates to a device for tensioning the closing spring of electric power switch actuating devices, in particular vacuum switches, in which the closing spring is connected to an eccentric arranged on the closing shaft and can be tensioned by electric motor as well as manually actuated pulling shaft and spur gear. the last spur of which is also arranged on the closing shaft, on which is also provided a latch for initiating the closing operation performed by the closing shaft, as well as a curve disc operatively connected to the closing lever.

BACKGROUND OF THE INVENTION

In the case of electrical control devices, in particular high-voltage power switches and vacuum power switches, the vacuum power switch must be ready for the next switch-on operation once the switch-on operation has been completed, ie to ensure that the switch-on sequence is ON-ON-OFF. This assumes that the closing spring must be tensioned again after the closing operation is completed, if the device is to be ready for the next closing operation. In this case, the closing spring of the known vacuum power switch actuators is connected to an eccentric located on the closing shaft such that, when the latch connected to the closing shaft is released, the curved disc is also mounted on the closing shaft when rotated by about 180 °. As a tension spring, it pushes the closing lever operatively connected to the curve disc into a position corresponding to the closing position.

The preparation of the closing spring, designed as a tension spring, for the following closing action, ie its tension, can be carried out as described, for example, in the VEM Prospectus "Low-Oil Indoor Power Switches" Hn / 65/77 - 10000 - 7.77- IV / 1 / 17-565 - April 1976 by VEB Schaltgerätewerk Muskau. Turning on the electric motor with an intermediate gear cooperating with the rod rotates the ratchet, thereby tensioning the fastened spring on the ratchet.

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A device of this kind for controlling the movable switching contact of high voltage devices is also described in DD 296 378 A5.

In another known power vacuum switch control device in which the closing spring is in communication with an eccentric located on the closing shaft, the device located between the electric motor and the closing shaft is a spur gear, the last spur of which is loosely mounted on the closing shaft. If the latch located on the actuating shaft is released in this actuating device, the eccentric and the actuating shaft with the curve disc rotate by about 180 [deg.] Due to this release of the tensioned closing spring. In this movement of the closing shaft, the eccentric mounted thereon, as a result of the movement energy, passes around the latch for blocking the return movement, whereby the closing spring is partially tensioned again. Upon downstream movement of the closing shaft and thus of the eccentric, the partially tensioned closing spring is released again and accelerates the movement of the closing shaft with its eccentric in the opposite direction until the eccentric strikes the latch to block the reverse movement.

In order to prepare the closing spring for the following closing operation, in this known actuating device, the spur gear of the spur gear, which is loosely supported on the shaft, is provided in the region of the closing shaft with a projection in the shape of a circular segment arranged in axial direction. After the idle run, the circular segment of the freewheel spur wheel encounters a driver pin firmly attached to the start shaft, starts to engage the start shaft and thus the eccentric, and rotates it by about 180 ° to tension the start spring and power vacuum switch. for the next switching action.

The positions occupied by the engagement shaft and thus the eccentric are not tied to the use of an electric motor, but these positions of the engagement shaft and thus the eccentric and the pawl located on the engagement shaft are intrigued by the fact that the front-end and, on a drive shaft of a located spur gear that is operable to tension the drive spring by means of a manually operated tensioning shaft, the additional arrangement of which is not only desirable for revision, but is also required by many vacuum power switch operators alongside the propulsion electric motor.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The object of the invention is to provide a closing spring tensioning device for electric power switch actuators, in particular vacuum switches, in which the closing spring, designed as a tension spring, is connected to an eccentric arranged on the closing shaft and tensionable by both an electric motor and manually and a spur gear, the last spur of which is also arranged on the engagement shaft, on which a latch for triggering the engagement performed by the engagement shaft as well as a curve disc operatively coupled to the engagement lever is located.

This object is solved by the invention which is based on the fact that the last spur gear of the gear is arranged by a freewheel bearing on the closing shaft so that at the beginning of the closing spring tension the eccentric and thus the closing shaft are immediately carried away from the position in which they are. and which is in the direction of rotation of the eccentric behind the lower dead center of the closing shaft, while in the operating phase when the closing shaft is rotated through its lower dead center, the last spur in its position is locked by the freewheel bearing as well as operatively connected to the other spur gears.

In order to ensure the long-term functional reliability of the freewheel bearing and to ensure a long service life of the power switch control device, it is useful if the freewheel bearing consists of its own freewheel and of thrust bearings arranged on both sides of the freewheel. It is preferred that both the freewheel and the thrust bearings consist of needle bearings, but other types of bearings may be used which do not impair the function of the freewheel bearing.

In another embodiment of the invention, the freewheel freewheel ring is formed by the outer circumferential surface of the start shaft, the diameter of the freewheel needles is less than the distance between the outer perimeter surface of the freewheel and the inner circumference of the outer circumference. in the form of saw teeth such that the greatest distance from the inner circumference of the outer ring is always opposite to the rotational direction of the lying sides of the sawtooth-shaped surfaces. To ensure the functional reliability of this freewheel, the saw tooth shaped surfaces located on the inner periphery of the outer freewheel book have a small pitch.

According to a further feature of the invention, the freewheel freewheel bearing needles acting to tension the tension spring against the low-pitch sawtooth surfaces are pressurized by the flexible tines so that they are compressible in the clamping direction on the sawtooth-shaped surfaces arranged on the outer ring. This ensures that immediately after switching on the multi-stage spur gear by means of an electric motor or a manual pulling shaft, the last spur gear mounted on the closing shaft rotates the closing shaft, which also carries the eccentric thereon, thereby engaging the closing and closing spring. is ready for the next switch-on operation. The result of this solution is that the tensioning time is shortened as a result of the direct rotation of the closing shaft and thus of the eccentric, and since the spur gear is loaded and has no free running, it also reduces wear.

Suitable resilient bodies acting on the idles of the freewheel bearing are preferably elastic stirrups which are supported against the wall of the outer ring of the freewheel bearing. Of course, other resilient bodies for acting on the freewheel needles, which do not have the shape of the stirrups exemplified, are possible and can be used according to the invention.

Thus, a solution according to the invention is provided for tensioning the closing spring of the actuating devices of power electric switches, in particular of vacuum power switches, in which the last spur gear of the spur gear is connected to the closing shaft by a freewheel bearing. This achieves a shortening of the time required for the tensioning of the closing spring and, moreover, that the spur gear starts to run under load, thereby reducing its wear.

During the engagement cycle, the last spur gear does not rotate, either because of the freewheel bearing through which it is mounted on the spur shaft, but also because the teeth of this spur gear engage another spur gear.

An advantageous solution of the device according to the invention consists in that a single-stage spur gear is connected to the last spur gear located on the closing shaft above the freewheel bearing, the largest diameter spur of which engages a small-diameter spur gear mounted on a manual pull-on shaft. and a freewheel bearing with a collar provided with a collar is also mounted on the hand-drawn shaft, with a guide spring mounted on the outer periphery of the collar, one end of which is mounted on a stop member provided on the collar provided and the other end mounted on a stop member , which is one of the two stop elements located on the rear wall of the switch actuator. While the directive spring, preferably designed as a torsion spring, can be disposed on the shank of the sleeve provided with a collar, the two stop elements located on the rear wall of the actuating device can be offset relative to each other, for example by 180 °. However, the same effect can also be achieved at a different offset angle of these stop elements, for example if they are offset by 30 ° to each other. The hand-held drive shaft is preferably mounted on the one hand in the rear wall and on the other hand in the front wall of the actuating device.

In order to prevent, in the power switch, in particular the power vacuum switch, the reverse rotation of the eccentric by the closing spring from the lower dead center of the closing spring, or to prevent this return movement from engaging the eccentric and thereby the closing shaft a position lying in the upward direction of the eccentric beyond the lower dead center of the closing shaft, but also in particular to prevent the closing of the closing latch when the power vacuum switch is prepared for the next closing operation after the latch is connected to the closing shaft reversing the eccentric and latch associated with the start shaft, both after the power switch has been turned on and after the latch has been struck. This is due to the fact that after the stop with the sleeve and the collar of the provided stop element on the closest, in the direction of rotation of the housing on the rear wall of the switch actuator, the stop element, both stop elements together with the freewheel bearing and housing form a single-stage reverse blocking device. the spur gear and hence the closing shaft. In this case, the directing spring is tensioned after the stop element, which is connected to the housing, on the stop element located on the rear wall of the actuating device nearest to the direction of rotation.

By creating a reverse rotation angle limited by the locking device, not only the possible reverse rotation of the closing shaft with its components is prevented, but it is also ensured that after a hard impact of the latch on the closing latch, the latch coupled to the closing shaft can rotate back by a small angle . By releasing the impact force that occurs, this not only prevents the closing latch from locking, but at the same time it is ensured that no failure can occur when the closing spring is actuated by an electric motor or the closing spring is actuated by a hand crank.

In the device according to the invention, it is advantageous if the freewheel bearing releases the sleeve provided with a collar so that when the directing spring is released, the freewheel bearing releases the sleeve provided with the collar so that when the directing spring is released. the housing rotatable in the opposite direction until the stop element connected to the housing strikes the second stop element located on the rear wall of the switch actuator. In order to be able to tension the closing spring with respect to the low torque of the engine, and also to achieve a low speed of the last spur gear and hence the closing shaft, the single-stage spur gear has a large low-speed transmission.

In this connection, it is expedient that the single-stage spur gearing with a large gear ratio slowly consists of an elliptical bushing which can be mounted on the shaft of an electric motor, on which an elastic toothed ring extends externally via a ball bearing. the shaft of an electric motor concentrically arranged, the toothing of two superimposed rings, one of which is fixed to the body of the electric motor and the other ring is fitted with a twin spur wheel, the spur of the smallest diameter being engaged with the last spur gear located on the switch and the elastic outer ring has fewer teeth than one of the two superimposed internally toothed rings, and the other internally toothed ring has the same number of teeth as the elastic outer ring. Zuben

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments of the invention are shown in the drawings, wherein FIG. 1 is a view of a start shaft with the last spur gear mounted thereon, in a stop position, and FIG. 2 is a view of a start shaft with the last spur gear arranged thereon, in a start position; FIG. Fig. 3 is a schematic view of the freewheel of the freewheel bearing through which the last spur gear is mounted on the closing shaft; Fig. 4 is a schematic view of the freewheel of Fig. 4. 3 in front view, in connection with thrust bearings located on the front sides, FIG. Fig. 5 is a schematic view of the actuator shaft in the switch-off position of Fig. 1, in operative connection with a single-stage spur gear and a manual tensioning shaft; Fig. 6 is a schematic view of the actuator shaft of Fig. 1. 5 in the closing position; and FIG. 7 is a top view of the closing shaft of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, an eccentric 2, a curved disk 3 and a latch 4 are also located on the closing shaft 5 of the electric power switch control device, in particular the vacuum power switch, next to the last spur gear 1 of the multi-stage spur gear no longer shown. switching on. While the eccentric 2, the cam disk 3 and the latch 4 are fixedly mounted on the engaging shaft 5, the last spur gear 1 of the multi-stage spur gear is supported on the engaging shaft 5 by a freewheel bearing 6, shown in more detail in Figures 3 and 4. In the switch-off position, the closing spring 7, designed as a tension spring connected to the eccentric 2, is in the tensioned state, i.e. the vacuum power switch control device is ready to start the closing operation. The closing operation is triggered by releasing the latch 4 by means of another latch, not shown here, which is part of the control device. After the closing operation has been started by releasing the latch 4, not only the latch 4, but also the eccentric 2 and hence the actuating shaft 5 and the curve disc 3 are rotated in the direction of the arrow 8 by the closing spring 7 by about 180 °. also with a closing lever (not shown).

In this case, the eccentric 2 passes through the lower dead center 9 of the closing shaft 5 as a result of the movement energy, until the closing shaft 5, the eccentric 2 and the pawl 4 assume the position shown in FIG. 2, in which the trigger spring is in the off state.

Thus, if the closing spring 7 is to be tensioned again in order to prepare for the next closing operation, the closing shaft 5, the closing spring eccentric 7, the curve disc 3 and the latch 4 should be shown from the position shown in FIG. 2 to the position shown in FIG. 1, in which the closing spring 7 is tensioned. Thus, the last spur gear I of the multi-stage spur gear, immediately at the start of actuation of the multi-stage spur gear, is driven by a freewheel bearing 6 via a drive shaft 5 and hence also an eccentric 2 until it assumes the position shown in FIG. 1, in which the closing spring 7 is tensioned and is thus ready to start another closing operation. Since the engaging shaft 5 and the eccentric 2 are immediately carried by the multi-stage spur gear, the tensioning time of the closing spring 7 is shortened. The multi-stage spur gear rotates under load so that no idling occurs and the wear is greatly reduced. When using a single-stage spur gear, the advantages are the same.

According to FIG. 4, the freewheel bearing 6, by means of which the last spur gear 1 of the multi-stage spur gear according to FIG. 1a is mounted on the clutch shaft 5, consists of its own freewheel 10 and two supporting bearings 11 which limit the freewheel 10. 10 as well as thrust bearings 11 are needle bearings. As can be seen from FIG. 3, the inner ring of the freewheel bearing 6 is formed by the circumferential surface of the engaging shaft 5, and in the interspace 12 between this circumferential surface and the inner circumference of the outer ring 13 of the freewheel 10. between the outer circumferential surface of the engaging shaft 5 and the inner circumference of the outer ring 13 of the freewheel 10. These needles 14 are operatively connected to the small-pitch sawtooth plates 15, which are arranged equally spaced on the inner circumference of the outer ring 13 of the freewheel 10. that their greatest distance from the inner circumference of the outer ring 13 is always on the opposite side of the sawtooth-shaped tabs 15 with respect to the direction of rotation (arrow direction 8 - Figs. 1 and 2). The freewheel needles 14 are acted upon by the force of the elastic bodies 16, which are designed as elastic stirrups, by means of which the needles 14 can be pressed against the sawtooth-shaped surfaces 15 arranged on the outer ring of the freewheel 10, i.e. in the clamping direction. This creates the conditions that, immediately upon switching on the control of the multi-stage spur gear, i.e. even when the last spur gear I is rotated to tension the closing spring 7, the closing shaft 5 and thus the eccentric 2 are carried by the last spur gear I, about 180 ° completes the tensioning of the closing spring 7.

In the apparatus of FIGS. 5, 6 and 7, a single-stage spur gear 17 is used. In addition to the last spur gear 18 of this single-spur gear 17, an eccentric 2, a curve disc 3 and a latch 4 are again located on the control shaft 5. of the closing latch 19, the closing operation is switched on. In this case, the eccentric 2, the cam disk 3 and the pawl 4 are fixedly mounted on the start shaft 5, while the last spur gear 18 of the single-stage spur gear 17 is mounted on the start shaft 5 via a freewheel bearing 6.

5, the closing spring 7, connected to the eccentric 2, is in the tensioned state, so that the control device is ready to start the closing operation of the vacuum power switch, it is clear from FIG. 6 that the closing spring 7 is released, wherein the closing spring 7, the eccentric 2 and hence the closing shaft 5 are in the upward position behind the lower dead center 9 of the closing shaft 5 in the direction of rotation of the eccentric 2.

If the closing spring 7 is removed from the position shown in FIG. 6, the tensioning shaft 5, the eccentric 2 together with the closing spring 7, the curve disc 3 and the latch 4 must be brought back from the position shown in FIG. 6 to the position shown in FIG. . For this purpose, the closing shaft 5, which also carries the eccentric 2, is rotated by means of the last spur gear 18 of the single-stage spur gear 17, which after actuation is controlled by an electric motor 20 serving as a pulling motor or also by a manual pulling shaft 21 (Fig. 7). ). This entrainment lasts until the eccentric 2 assumes the position shown in FIG. 5, in which the closing spring 7 is again tensioned and thus ready for the next closing operation.

However, in order to ensure that the latch 4 can be rotated back by a small angle after the hard stop of the latch 4 on the latch 19, the latch 4 shown in FIG. 7, which, however, allows the latch 4 to be reversed at a small angle. This means that the stop force can be released, thereby preventing the latch 19 from blocking. However, at the same time, the blocking device 22 also achieves a possible failure of the latch. reverse rotation of the actuating shaft 5 with its components, thus also with the closing spring 7, or that the reverse rotation is at least limited.

As can be seen from FIG. 7, the spur gear 23 having the largest diameter in the single-stage spur gear 17 engages a smaller diameter spur gear 24 mounted on the manual pull shaft 21. Further, a freewheel bearing is mounted on the manual pull shaft 21. 25, in which the housing 27 is provided with a collar 26 on the outer periphery of which is a directing spring 28. While one end 29 of the directing spring 28 is mounted on a stop element 30 disposed on the housing 27, the other end 31 of the directing spring 28 located on the shank 32 of the housing 27, is connected to one stop element 33 of two stop elements 33, 35 disposed 180 ° relative to each other on the rear wall 34 of the switch actuator. In this solution, the hand winding device 21 is mounted not only in the rear wall 34 but also in the front wall 36 of the switch actuator.

By means of the locking device 22 formed by the directing spring 28, the stop elements 30, 33, 35 and the freewheel bearing 25, the return angle of the eccentric 2 is limited both when the vacuum power switch is switched on and the latch 4 is connected to the start shaft 5. This occurs in that, after the stop element 30 connected to the housing 27 has been hit on the nearest stop element 33 arranged in the direction of rotation of the housing 22, the two stop elements 30, 33 together with the free bearing 25 and the housing 27 form a blocking device 22 If the two stop elements 30, 33 are in contact with each other, the directing spring 28 is tensioned.

On the other hand, when preparing the power vacuum switch for the next switch-on operation by switching on the single-stage spur gear 17 by means of an electric motor 20 as a pulling motor or by a manual pulling shaft 21, the free bearing 25 releases a sleeve 27 provided with a collar 26. the sleeve 27 turns in the opposite direction. This rotation continues until the stop element 30, connected to the housing 27, impacts the second stop element 35 located on the rear wall 34 of the switch actuator.

As a single-stage spur gear 17, the spur gear has a high gear ratio, which is also known from the Harmonic-drive-Getriehe control unit. In this, one ring 37 of two superimposed rings 37. 38 is mounted on the body 39 of the electric motor 20, and on the other ring 38 a dual spur gear 40 is placed, whose spur gear 41 with the smallest diameter engages the last spur gear 18 positioned. 5. Using a single-stage spur gear 17 and adapting it to the ratio of the power switch control device, in particular the vacuum power switch, but also with the manual pull shaft 21 and the backstop 22, the device according to the invention favorably reduces the built-up space. with respect to spur gears 17 and thus cost reduction.

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Claims (17)

A device for tensioning the closing spring of electric power switch actuating devices, in particular vacuum switches, in which the closing spring, designed as a tension spring, is connected to an eccentric arranged on the closing shaft and is tensionable by both an electric motor and manually operated pulling the last spur of which is also arranged on the closing shaft, on which is also provided a latch for triggering the closing operation performed by the closing shaft, as well as a curve disc operatively connected to the closing lever, characterized in that the last front end the spur gear (1) is arranged on the closing shaft (5) by means of a freewheel bearing (6) such that at the beginning of the closing spring (7) tensioning the eccentric (2) and thus the closing shaft (5) is the last spur gear (1) bezprost in the direction of rotation of the eccentric (2) behind the lower dead center (9) of the closing shaft (5), while in the starting phase when the closing shaft (5) is rotated through its lower dead center (9) ), the last spur gear (1) is locked in position by the freewheel bearing (6) as well as by a functional connection with the other spur gears. Device according to claim 1, characterized in that the freewheel bearing (6) consists of a freewheel (10) and support bearings (11) arranged on both sides of the freewheel (10). Device according to claim 1 and 2, characterized in that the freewheel (10) and the thrust bearings (11) of the freewheel bearing (6) are needle bearings. Device according to claims 1-3, characterized in that the inner ring of the freewheel bearing (6) is formed by the outer circumferential surface of the closing shaft (5), the diameter of the needles (14) of the freewheel (10) being smaller than the distance between the outer a circumferential surface of the engaging shaft (5) and an inner circumference of the outer ring (13) of the freewheel (10), and arranged on the inner circumference of the outer ring (13) Device according to claim 4, characterized in that the sawtooth-shaped surfaces (15) arranged on the inner circumference of the outer ring (13) of the freewheel (10) have a small pitch. Apparatus according to claims 1 to 5, characterized in that the freewheel (10) needles (10) of the freewheel bearing (6) are pressurized by the resilient bodies (16) in such a way that they can be pressed into the clamping direction of the flats (15). saw teeth arranged on the outer ring (13) of the freewheel (10). Device according to claim 6, characterized in that the elastic bodies (16) are elastic stirrups which are supported on the wall of the outer ring (13) of the freewheel (10) of the freewheel bearing (6). Device according to claims 1 to 7, characterized in that a single-stage spur gear (17) is connected to the last spur gear (18) located on the closing shaft (5) above the idle bearing (6), the spur gear (23) of which the largest diameter is engaged with the small diameter spur gear (24) mounted on the manual pull shaft (21), and a freewheel bearing (25) with a bushing (27) equipped with a collar (26) is further provided on the manual pull shaft (21). ), wherein a guide spring (28) is provided on the outer periphery of the housing (27), one end (29) of which is mounted on a stop element (30) located on the housing (27) provided with a collar (26) and the other end (31). ) is mounted on a stop element (33) which is one of two stop elements (33, 35) arranged on the rear wall (34) of the switch actuator. Apparatus according to claim 1, characterized in that the directing spring (28) is arranged on a shank (32) of a housing (27) provided with a collar (26). Apparatus according to claims 8 and 9, characterized in that the directive spring (28) is formed by a torsion spring. Device according to Claims 8 to 10, characterized in that the two stop elements (33, 35) arranged on the rear wall (34) of the actuating device are offset relative to each other at a predetermined angle, preferably at an angle of 180 °. Device according to Claims 8 to 11, characterized in that the manual pulling shaft (21) is mounted on the one hand in the rear wall (34) and on the other hand in the front wall (36) of the control device. Apparatus according to Claims 8 to 12, characterized in that, after switching on, as well as the impact of the pawl (4) connected to the closing shaft (5), on the closing pawl (19), the recoil angle of the eccentric (2) is and a latch (4) limited by the stop element (30) fitted to the nearest stop (30) in the direction of rotation of the housing (27) on the rear wall (34) of the switch actuator when the stop element (27) and the collar (26) (33), the two stop elements (33, 35) together with the freewheel bearing (25) and the bushing (27) form a blocking device (22) for the return of the single-stage spur gear (17) and hence the closing shaft (5). - 13 uniformly distributed sawtooth-shaped surfaces (15) such that the sides of the saw-toothed flats (15) are opposite to the inner circumference of the outer ring (13) and lie opposite to the direction of rotation. Apparatus according to claims 8 to 13, characterized in that, after the stop element (30), which is connected to the housing (27), strikes the stop element (33) in the direction of rotation nearest to the rear wall ( 34) of the switch actuating device, the directive spring (28) is tensioned. - 14, - 15 while the stop element (30) connected to the housing (27) encounters a second stop element (35) located on the rear wall (34) of the switch actuator. Apparatus according to claims 8 to 14, characterized in that, in preparing the power switch for the following engaging operation, the single-stage spur gear (17) is started by an electric motor (20) as a motor or by a manual motor shaft (21). the bearing (25) releases the sleeve (27, provided with a collar (26)), such that after release of the directing spring (28), the sleeve (27) is rotatable in the opposite direction, Apparatus according to claims 8 to 15, characterized in that the single-stage spur gearing (17) has a large gear ratio. Apparatus according to claims 8 to 16, characterized in that the single-stage high-speed spur gear (17) consists of an elliptical bushing which can be mounted on the shaft of an electric motor (20) on which the ball bearing is elastically mounted from the outside a toothed ring which, in its large axis of the ellipse, extends into the inner, with respect to the shaft of the electric motor (20) of concentrically arranged, toothing of two superimposed rings (37, 38) of which one ring (37) is mounted on the electric motor body (39) (20) and a second spur gear (40) is disposed on the second ring (38), the spur gear (41) having the smallest diameter engaging the last spur gear (18) located on the engaging shaft (5), and an elastic ring with external teeth has fewer teeth than one of the two superimposed internally toothed rings (37, 38) and the other of the rings , provided with an internal toothing, has the same number of teeth as the elastic ring provided with external toothing. p in ClX Ot> 3T 1 About the X? . 2 p v al ·? - s t ot »r - 3 Fig - 4 Ofc »r - 5 P V - S £