NZ283744A - A 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

New Zealand No. 283744 International No.

TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION Priority dates: 12.04.1994;30.01.1995; Complete Specification Filed: 04.04.1995 Classification:^) H01H3/30 Publication date: 24 February 1998 Journal No.: 1425 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of Invention: Device for tensioning the cut-in spring in actuator units for circuit breakers, in particular vacuum circuit breakers Name, address and nationality of applicant(s) as in international application form: HOLEC HOLLAND N.V., Tuindorpstraat 61, NL-7555, CS Hengelo, The Netherlands New Zealand No. 283744 International No. PCT/EP95/01232 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of Invention: Device for tensioning the cut-in spring in actuator units for circuit breakers, inparticular vacuum circuit breakers Name, address and nationality of applicant(s) as in international application form: HOLEC HOLLAND N.V., of Tuindorpstraat 61, NL-7555, CS Hengelo, The Netherlands - I ~ 283744 Device for tensioning the closing spring of drive devices for electrical circuit breakers, in particular vacuum circuit breakers The invention relates to a device for tensioning the closing spring of drive devices for electrical circuit breakers, in particular vacuum circuit breakers, in the case of which the closing spring, which is designed as a tension spring, is 10 connected to the eccentric which is fitted on the closing shaft, and can be tensioned both by sua electric motor and by a manual tightening shaft with the interposition of spur gearing, the last spur gear of the latter likewise being arranged on the closing 15 shaft, which is also fitted with the catch for initiating a closing process by means of the closing shaft and with the cam disc which is operatively connected to the closing lever.

In the case of electrical switchgear, that is 20 to say in the case of high-voltage circuit breakers, in particular vacuum circuit breakers, when the closing process is completed it is important for the vacuum circuit breaker to be prepared for the next closing process again so that an ON-OFF-OFF switching sequence 25 is ensured. This is dependent on the closing spring which produces the closing process being tensioned again after completion of the closing process, so that the next closing process is prepared for. In this event, in the case of known drive devices for vacuum 30 circuit breakers, the closing spring is connected to an eccentric which is located on a closing shaft, so that, when a catch which is likewise arranged on the closing shaft is released, a cam disc which is furthermore provided on the closing, shaft forces, during its 35 rotation through about 180°, the closing lever, which is operatively connected 'to the cam disc, into a position which corresponds to the connected position, as a result of the action of the closing spring, which is designed as a tension spring. p .'V-*'; '>F'rfC^| ' £& GC.T 1336 283744 The preparation of the closing spring, which is designed as a tension spring, for the next closing process, that is to say its tensioning, can be carried out, for example, as cam be seen in the VEM company document "Olarme Innenraun-Leis tungs schalter" [Low-oil content interior circuit breakers] Hn/65/77 - 10000-7.77-IV/1/17-565 - April 1976, from the VEB Switchgear Works, Muskau in that a ratchet disc is rotated by applying a control voltage to an electric motor with the interposition of geari&g which interacts with a push rod, such that the closing spring, which is mounted eccentrically on this ratchet disc, is tensioned. Such gearing is also provided to operate the moving switching contact in high-voltage switchgear according to DD 296 37B A5.

In the case of the known drive device for vacuum circuit breakers, in which the closing spring is connected to an eccentric which is located on the closing shaft, the gearing which is arranged between the electric motor and the closing shaft is spur gearing, whose last spur gear is mounted loosely on the closing shaft. In the case of this drive device, if the catch which is arranged on the closing shaft is released, then the eccentric, and thus the closing shaft with the cam disc as well, . are rotated through about 180° as a result of the release, linked thereto, of the tensioned closing spring. During this movement sequence of the closing shaft, the eccentric which is located on it moves past the catch of a non-retum stop as a result of the movement energy, so that the closing spring is in consequence partially tensioned again. During the reversal of the movement of the closing shaft, and thus of the eccentric as well, which follows this, the partially tensioned closing spring is relieved in tension again and accelerates the closing shaft with its eccentric in the opposite rotation direction, to be precise until the eccentric stops on the catch of the non-return stop.

In the case of this known drive device, in 2837 CO o-> CO a c3 -S oa ec T»« order now to prepare the closing spring for the next closing process, the last spur gear, which is mounted loosely on the closing shaft, of the spur gearing has a projection in the region of the closing shaft, which projection mans in the axial direction and is in the form of a circle segment. After passing through an idling region, the projection, which is in the form of a circle segment, of the loosely mounted spur gear stops on a driver pin, which is firmly connected to the closing shaft, drives the closing shaft and thus the eccentric through a rotation of about 180° again, and the closing spring is under tension, so that the vacuum circuit breaker is prepared for the next closing process.

The positions which the closing shaft and thus the eccentric assume are not linked to the use of an electric motor, but the closing shaft and thus the eccentric and the catch which is arranged on the closing shaft assume these positions even when the operation of the spur gearing and thus of the last spur gear arranged on the closing shaft can be operated to tension the closing spring by means of a manual tightening shaft whose additional arrangement is necessary not only to carry out inspections but is also required by a largo number of operators of vacuum circuit breakers, in addition to the electric motor ad a drive.

The invention is based on the object of providing a device for tensioning the closing spring of drive devices for electrical circuit breakers, in particular vacuum circuit breakers, in the case of which the closing spring, which is designed as a tension spring, is connected to the eccentric which is fitted on the closing shaft, and can be tensioned both by an electric motor and by a manual tightening shaft with the interposition of spur gearing, 1 the last spur gear of the latter likewise being arranged on the closing shaft, which is also fitted with the catch for initiating a closing process by means of the closing 4 - 283744 shaft and with the cam disc which is operatively connected to the closing lever, in which the spur gearing operates without idling, and any backlash of the eccentric after closing is prevented or limited by the closing spring, and jamming of the closing catch on the catch which is connected to the closing shaft during the preparation of the circuit breaker for the next closing process is avoided.

According to the invention, this is achieved in that the last spur gear of the spur gearing is arranged via a freewheeling bearing on the closing shaft, in such a manner that, at the start of tensioning of the closing spring, the eccentric and thus the closing shaft cam be driven directly by the last spur gear from a position in which they are located after the bottom dead centre of the closing shaft in the rotation direction of the eccentric towards the top, while,. in the phase of the closing process during rotation of the closing shaft beyond its bottom dead centre, the last spur gear is locked in its position by the freewheeling bearing and by the operative connection to the other spur gears of the spur gearing.

In this case, it is expedient in order to ensure long functional reliability of the freewheeling bearing and thus a long service life for the drive device for the circuit breaker if the freewheeling bearing is composed of an actual freewheeling mechanism and of in each case one supporting bearing, which supporting bearings are arranged on both sides of the freewheeling mechanism. Both the freewheeling mechanism and the two supporting bearings of the freewheeling bearing are preferably needle bearings, it also being possible to use any other bearing without limiting the function of the freewheeling bearing.

In a further refinement of the invention, the inner ring of the freewheeling mechanism of the freewheeling bearing is formed by the outer circumferential surface of the closing shaft, the diameter of the needles of the freewheeling mechanism -5 283744 is less than the distance between the outer circumferential surface of the closing shaft and the inner circumference of. the outer ring of the freewheeling mechanism, and sawtooth-shaped surfaces 5 are arranged distributed uniformly on the inner circumference of the outer ring, in such a manner that their greatest distance from the inner circumference of the outer ring is always provided on the side of the sawtooth-shaped surfaces which is opposite in the 10 rotation direction. In order to ensure the functional reliability of this freewheeling mechanism, the sawtooth-shaped surfaces which are arranged on the inner circumference of the outer ring of the freewheeling mechanism have a shallow gradient. 15 According to a further feature of the invention, the needles of the freewheeling mechanism of the freewheeling bearing, which act against the sawtooth-shaped surfaces having a shallow gradient, during tensioning of the closing spring, are subject to 20 the force of spring bodies in such a manner that they can be pressed onto the sawtooth-shaped surfaces of the outer ring of the freewheeling mechanism, that is to say in the clamping direction, thus ensuring that the closing shaft, and thus also the eccentric which is 25 arranged on the closing shaft, are driven directly during operation of the multistage spur gearing by means of an electric motor or by means of a manual tightening shaft by the last gearwheel which is seated on the closing shaft, so that the closing spring, which 30 is connected to the eccentric, is tensioned in order to prepare for the next closing process. The fact that the closing shaft and thus the eccentric are driven without any delay means that the tensioning times for . .tensioning the closing spring are not only relatively 3^ /short but, as a result of the fact that the spur cn -v, I ' gearing starts under load, that is to say no longer cS -*j jf •4 (< idles, the wear thereon is also reduced. 'i ir fr:!{ Spring clips which are supported on the outer ** V '' cn ; ring of the freewheeling mechanism of the freewheeling 2837 44 bearing are preferably used as spring bodies which act on the needles of the freewheeling mechanism of the freewheeling bearing. The invention also includes, of course, the use of any other spring body which acts on 5 the needles of the freewheeling mechanism and differs from the spring clip.

In this way, the invention provides a device for tensioning the closing spring of drive devices for electrical circuit breakers, in particular vacuum 10 circuit breakers, in which the last spur gear of the spur gearing is connected via a freewheeling bearing to the closing shaft. In consequence, shorter tensioning times are achieved for the tensioning of the closing spring and, in addition, this results in the spur 15 gearing starting under load, so that its wear is reduced.

During the closing process, the last spur gear does not also rotate, taking account of the freewheeling bearing via which it is arranged on the 20 closing shaft, or alternatively as a result of the fact that the teeth of this spur gear engage with the teeth of the next-following spur gear of the spur gearing.

A preferred refinement of the device consists in that a single-stage spur gearing is connected to the 25 last spur gear, which is arranged above the freewheeling bearing on the closing shaft, and its spur gear having the largest diameter engages with a spur gear which is mounted on the manual tightening shaft and has a smaller diameter, and a freewheeling bearing 30 is furthermore arranged on the manual tightening shaft and holds a bush, which is provided with a collar, on whose outer circumference a restoring spring is arranged, one of whose ends is mounted on a stop element, arranged on the bush which is provided with a ■ < collar, and the second end of which is mounted on a | stop' element of two stop elements which are arranged on the rear wall of the circuit breaker drive.

While the restoring spring, which is advantageously a rotating spring, may be arranged on the - 7 283744 OS i shank of the bush which is provided with a collar, the two stop elements which are mounted on the rear wall of the circuit breaker drive may be arranged such that they are offset through, for example, 180° with respect 5 to one another. The effect which is achieved, by the mutually offset arrangement of the stop elements can also be achieved at a different angle, for example if these stop elements are arranged offset through 30° with respect to one another. The manual tightening 10 shaft is preferably mounted in the rear wall of the circuit breaker drive as well as in its front wall.

Once the circuit breaker, in particular a vacuum circuit breaker, has been closed, in order to avoid the eccentric being turned back by the closing 15 spring in the direction of the bottom dead centre of the closing shaft, but at least to limit it such that at the start of tensioning of the closing spring the eccentric and thus the closing shaft assume a position which is located after the bottom dead centre of the 20 closing shaft in the rotation direction of the eccentric towards the top, but in particular also to prevent jamming of the closing catch after the catch which is connected to the closing shaft has stopped during the preparation of the vacuum circuit breaker 25 for the next closing process, not only is the backlash angle of the eccentric limited after the closing of the circuit breaker, but the backlash angle of the catch is also limited after said catch, which is connected to the closing shaft, stops on the closing shaft. 30 This is achieved in that, after the stop element, which is connected to the bush which is provided with a collar, has stopped on the stop element which is located first in the rotation direction of the . bush and is arranged on the rear wall of the circuit 351 breaker drive, the two stop elements form a non-return -v; ;■ stop together with the freewheeling bearing and the %'ij bush, which is provided with a collar, for the single-stage spur gearing, and thus for the closing shaft. In "? '• if Si f this case, the restoring spring is stressed when the .! 2837 44 btop element which is connected to the bush stops on the stop element which is located first in the rotation direction of the bush and. is arranged on the rear wall of the circuit breaker drive.

The provision of a backlash angle which is limited by the non-return stop not only prevents possible movement reversal of the closing shaft with its components after the closing process, but also ensures that, after the catch makes a hard stop on the 10 closing catch, the catch Vhich is connected to the closing shaft can rotate back through a small angle. The relief of the stress of the stop force which results from this not only cancels out any blocking of the closing catch but also ensures that no disturbsmces 15 occur when the closing spring is tightened by the electric motor or in the event of tightening by crank handle via the manual tightening shaft.

It is advantageous in this arrangement that, in the case of the device according to the invention, 20 during the preparation of the circuit breaker for the next closing process, by operation of the single-stage spur gearing via the electric motor, as a tightening motor, or of the manual tightening shaft, the freewheeling bearing releases the bush which is 25 provided with a collar, so that the bush can be rotated in the opposite direction as a result of the relief of the tension on the restoring Bpring, until the stop element, which is connected to the bush, stops on the second stop element, which is arranged on the rear wall 30 of the circuit breaker drive.

In order that the tensioning of the closing spring can be carried out taking account of a small motor torque, but also to achieve a low rotation speed of the last spur gear and thus of the closing shaft, 35 the single-stage gearing has a high step-down ratio.

In this case it is expedient to use gearing as single-stage spur gearing having a high step-down ratio, which gearing is composed of sun elliptical bush which cam be fitted onto the shaft of the electric 93 H ^ IQ !« iS - 9 283744 motor and holds on its outer circumference, via a ball bearing, ai* elastic ring which has external teeth and on its major ellipse axis, engages in the internal tooth system, which is arranged concentrically with respect 5 to the shaft of the electric motor, of two rings which are arranged one above the other, one ring of which is counted on the housing of the electric motor and the second ring is fitted with a double spur gear, of which the spur gear having the smallest diameter engages with 10 the last spur gear arranged on the closing shaft, the elastic ring which has external teeth having fewer teeth than one of the two rings which are provided with an internal tooth system and are arranged one above the other, the other ring which is provided with an 15 internal tooth system having the same number of teeth as the elastic ring which has external teeth.

The invention will be explained in more detail in the following text, with reference to an exemplary embodiment.

In the associated drawing: Fig. 1 shows the closing shaft with the last spur gear, which is fitted on it, of spur gearing in the open position, Fig. 2 shows the closing shaft with the last spur 25 gear, which is fitted on it, according to Fig. 1 in the closed position.

Fig. 3 shows a schematic illustration of the freewheeling mechanism of a freewheeling bearing, via which the last spur gear is arranged on the 30 closing shaft.

Fig. 4 shows a further schematic illustration of the freewheeling mechanism according to Fig. 3 in a front view, in conjunction with supporting bearings which are arranged at the ends, r . *■ ; Fig. 5 shows the closing shaft in the open position m £ according to Fig. 1, operatively connected to ^ I single-stage spur gearing as well as to the ^ f manual tightening shaft, C5+ Fig. 6 shows the closing shaft according to Fig. 5 in -10 CO CD CD CO C3 era OQ 0) e: 283744 the closed position, Fig. 7 shows the plan view of the closing shaft according to Fig. 6.

As Fig. 1 shows, in addition to the last spur gear 1 of multi-stage spur gearing which is not shown in more detail, an eccentric 2, a cam disc 3 as well as a catch 4, via which the closing process is initiated, are also arranged on the closing shaft 5 of a drive device for an electrical circuit breaker, in particular a vacuum circuit breaker. While the eccentric 2, the cam disc 3 and the catch 4 are arranged firmly on the closing shaft 5, the last spur gear 1 of the multistage spur gearing is arranged on the closing shaft 5 via a freewheeling bearing 6, which is illustrated in more detail in Figs. 3 and 4. The closing spring 7, which is connected to the eccentric 2 and is designed as a tension spring, is tensioned in the open position shown here, that is to say the drive device for initiating a closing process on the vacuum circuit breaker has been prepared. The initiation of the closing process is carried out by releasing the catch 4 by means of a further catch, which is likewise not illustrated in more detail and is part of the drive device. If the closing process is initiated by releasing the catch 4, then not only the ca.tch 4 but also the eccentric 2 and thus the closing shaft 5 and the cam disc 3, which is in this case operatively connected to a closing lever which is likewise not shown in more detail, are rotated by the closing spring 7 through about 180° in the direction of the arrow 8. At the same time, owing to the movement energy, the eccentric 2 passes through the bottom dead centre 9 of the closing shaft 5 until, finally, the closing shaft 5, the eccentric 2 and the catch 4 assume the position shown in Fig. 2,. in which the closing spring 7 is relieved of tension.

If it is now intended to tension the closing spring 7 in order to prepare for initiation of a further closing process, that is to say if the closing shaft 5, the eccentric 2 with the closing spring 7, the - -11 - 283744 u.; 0 1 <± sg , l£i | if li s if OS 04 M cam disc 3 and the cam 4 are intended to be moved from the position which can be seen in Fig. 2 into the position shown in Fig. 1, in which the closing spring 7 is tensioned, then the closing shaft 5, and thus the 5 eccentric 2, are driven by the last spur gear 1 of the multi-stage spur gearing directly at the start of the operation of the multi-stage spur gearing, via the freewheeling mechanism 6, until the eccentric 2 is in the position corresponding to Fig. 1, in which the 10 closing spring 7 is tensioned, that is to say has been prepared for initiation of the next closing process. The tensioning times for the closing spring 7 are shortened as a result of the fact that the closing shaft 5 and the eccentric 2 are driven directly by the 15 multi-stage spur gearing. The multi-stage spur gearing starts under load and, in consequence, there is no idling and the wear is considerably reduced. The same advantages result when single-stage spur gearing is used.

According to Fig. 4, the freewheeling bearing 6, via which the last spur gear 1 of the multi-stage spur gearing according to Figs. 1 and 2 is arranged on the closing shaft 5, is composed of the actual freewheeling mechanism 10 and the two supporting 25 bearings 11, which bound the freewheeling mechanism 10 at the ends. Both the freewheeling mechanism 10 and the supporting bearings 11 are needle bearings. As can be seen in conjunction with Fig. 3, the inner ring of the freewheeling mechanism 10 of the freewheeling bearing 6 30 is formed by the outer circumferential surface of the closing shaft 5, and needles 14 are arranged in the intermediate space 12 between this circumferential surface and the inner circumference of the outer ring 13 of the freewheeling mechanism 10, the diameter of 35 which needles 14 is smaller than the distance between the outer circumferential surface of the closing shaft 5 and the inner circumference of the outer ring 13 of the freewheeling mechanism 10. These needles 14 are operatively connected to sawtooth-shaped surfaces 15 0 J - -12 283744 UJ 0 tJ— -- i o! 1 -r i ir^ ^5- S8 $5 OS OQ ipi . 2C which have a Bhallow gradient and are arranged distributed uniformly on the inner circumference of the outer ring 13 of the freewheeling mechanism 10, to be precise in such a manner that their greatest distance from the inner circumference of the outer ring 13 is always provided on that side of the sawtooth-shaped surfaces 15 which is opposite in the rotation direction (direction of the arrow 8 - Figs. 1 and 2} . Iii this case, the needles 14 of the freewheeling mechanism 10 of the freewheeling bearing 6 are subject to the force of spring bodies 16, which are designed as spring clips, so that the needles 14 can be pressed onto the sawtooth-shaped surfaces 15 of the outer ring 13 of the freewheeling mechanism 10, that is to say in the clamping direction. This provides the preconditions for the closing shaft 5 and thus the eccentric 2, as well, being driven by the last spur gear 1 directly on initiation of the operation of the multi-stage spur gearing, that is to say also the rotation of the last spur gear 1, for the purpose of tensioning the closing spring 7, until the tensioning process of the closing spring 7 is completed after rotation through about 180°.

The device according to Figs. 5; 6 and 7 is initially based on the use of single-stage spur gearing 17. In addition to the last spur gear 18 thereof, an eccentric 2, a cam disc 3 and a catch 4 are also once again arranged on the closing shaft 5 of the circuit breaker drive, the closing process being initiated via the catch 4 after being released by a closing catch 19. In this case, the eccentric 2, the cam disc 3 and the catch 4 are arranged firmly on the closing shaft 5, while the last spur gear 18 of the single-stage spur gearing 17 is arranged via the freewheeling bearing 6 on the closing shaft 5.

While the closing spring 7, which is connected to the eccentric 2 and is designed as a tension spring, is tensioned in the open position which can. be seen in Fig. 5, so that the drive device has been prepared for 283744 initiating a closing process on the vacuum circuit breaker, Fig. 6 shows the situation in which the closing spring 7 is relieved of tension, the closing spring 7, the eccentric 7 [sic] and thus the closing 5 shaft 5 being in a position which is after the bottom dead centre 9 of the closing shaft 5, in the rotation direction of the eccentric 2 towards the top.

If, starting from the position of the closing spring 7 illustrated in Fig. 6, it is intended to 10 tension this closing spring 7 in order to initiate a further closing process, it is necessary to move the closing shaft 5, the eccentric 2 with the closing spring 7, the cam disc 3 and the catch 4 from the position which can be seen in Fig. 6 into the position 15 according to Fig. 5. For this purpose, the closing shaft 5 and thus the eccentric 2 are driven by the last spur gear 18 of the single-stage spur gearing 17, directly after its operation by an electric motor 20 as a tightening motor, once said motor has received a 20 control voltage, or else by the manual tightening shaft 21 (Fig. 7) . This driving process is carried out until the eccentric 2 has assumed the position which cam be seen in Fig. 5, in which the closing spring 7 is tensioned, that is to say it has been prepared for 25 initiating the next closing process.

However, in order now to ensure that the catch 4 which is connected to the closing shaft 5 can rotate back through a small angle after the catch 4 has made a hard stop on the closing catch 19, a non-return stop 22 30 is also provided, as is shown in Fig. 7, by means of which a limited backlash angle is made available for the catch 4 to rotate backwards. However, this means that the stop force can be relieved of stress and that any locking of the closing catch 19 is thus precluded. In addition, the non-return stop 22 at the same time also achieves the result that, after the closing process, any possible movement reversal of the closing shaft 5 with its components, that is to say the closing spring 7 as well, is prevented or, however, at least § I® / * ; SC 1 283744 limited.

As" Fig. 7 shows, the spur gear 23 having the largest diameter of the single-stage spur gearing 17 engages with a spur gear 24 which is mounted on the manual tightening shaft 21 and has a small diameter. Furthermore, a freewheeling bearing 25 is arranged on the manual tightening shaft 21 and holds a bush 27, which is provided with a collar 26 and on whose outer circumference a restoring spring 28 is arranged. While one end 29 of the restoring spring 28 is mounted on a stop element 3 0 which is arranged on the bush 27, the second end 31 of the restoring spring 28, which is arranged on the shank 32 of the bush 27, is connected to one stop 'element 33 of two stop elements 33; 35 which are mounted offset through 180° with respect to one another on the rear wall 34 of the circuit breaker drive. In this design, the manual tightening shaft 21 is mounted not only in the rear wall 34 but also in the front wall 36 of the circuit breaker drive.

The non-return stop 22, which is formed essentially by the bush 27, the restoring spring 28, the stop elements 30; 33; 35 and by the freewheeling bearing 25, limits not only the backlash angle of the eccentric 2 after closing of the vacuum circuit breaker but also the backlash angle after the catch 4, which is connected to the closing shaft 5, has stopped on the closing catch 19. This is achieved in that, after the stop element 30 which is connected to the bush 27 has stopped on the stop element 33 which is located closest in the rotation direction of the bush 27, the two stop elements 30; 33, together with the freewheeling bearing 25 and the bush 27, form a non-return stop 22 for the single-stage spur gearing 17 and thus for the closing shaft 5. If the two stop elements 30; 33 are in contact with one smother, then the restoring spring 28 is stressed.

In contrast, in the phase when the vacuum circuit breaker is being prepared for the next closing process, to be precise by operation of the single-stage 28374 spur gearing 17 via the electric motor 20 as a tightening'motor, or of the manual tightening shaft 21, the freewheeling bearing 25 releases the bush 27, which is provided with a collar 26, so that the bush 27 is 5 rotated in the opposite direction by relieving the stress on the restoring spring 28. This rotation continues until the stop element 30, which is connected to the bush 27, stops on the second stop element 35, which is arranged on the rear wall 34 of the circuit 10 breaker drive.

Spur gearing having a high step-down ratio, as is also known as harmonic-drive gearing, is used as the single-stage spur gearing 17. In this case, one ring 37 of two rings 37; 38 of this gearing which are arranged 15 one above the other are mounted on the housing 39 of the electric motor 20, and the second ring 38 is fitted with a double spur gear 40, whose spur gear 41 having the smallest diameter, engages with the last spur gear 18, which is arranged on the closing shaft 5. As a 20 result of the use of the single-stage spur gearing 17 and its adaptation to the conditions of the circuit breaker drive for a circuit breaker, in particular a vacuum circuit breaker, and taking account of the manual tightening shaft 21 as well as the non-return 25 stop 22, the device according to the invention at the same time has an influence on a reduction in the space occupied by the spur gearing, and thus on the costs.

Claims (19)

1. 28 3 7 4 4

2. WO 95/27992 - 16 - PCT/EP95/01232 V*;Patent claims;1. Device for tensioning the closing spring of drive devices for electrical circuit breakers, in 5 particular vacuum circuit breakers, in the case of which the closing spring, which is designed as a tension spring, is connected to the eccentric which is fitted on the closing shaft, and can be tensioned both by an electric motor and by a manual tightening shaft 10 with the interposition of spur gearing, the last spur gear of the latter likewise being arranged on the closing shaft, which is also fitted with the catch for initiating a closing process by means of the closing shaft and with the cam disc which is operatively 15 connected to the closing lever, characterized in that the last spur gear of the spur gearing is arranged via a freewheeling bearing on the closing shaft,;in such a manner that, at the start of tensioning of the closing spring, the eccentric and thus;20 the closing shaft can be driven directly by the last spur gear from a position in which they are located after the bottom dead centre of the closing shaft in the rotation direction of the eccentric towards the top, while, in the phase of the closing 25 process during rotation of the closing shaft beyond its bottom dead centre, the last spur gear is locked in its position by the freewheeling bearing and by the operative connection to the other spur gears of the spur gearing.;30 2. Device according to Claim 1, characterized in that the freewheeling bearing is composed of the freewheeling mechanism and of in each case one supporting bearing , which supporting bearings are arranged on both sides of the freewheeling mechanism.;35;

3. Device according to Claim 1 or Claim 2,;characterized in that both the freewheelinglnjftltacittSllsfiroperty and the supporting bearings of the Office of NZ;2,3 DEC 1997 received;-17- *8 3 74 4 freewheeling bearing are needle bearings.

4. Device according to any one of Claims 1 to 3, characterized in that the inner ring of the freewheeling mechanism of the freewheeling bearing is 5 formed by the outer circumferential surface of the closing shaft, in that the diameter of the needles of the freewheeling mechanism is less than the distance between the outer circumferential surface of the closing shaft and the inner circumference of 10 the outer ring, of the freewheeling mechanism,: and in that sawtooth-shaped surfaces are arranged distributed uniformly on the inner circumference of the outer ring, in such a manner that their greatest distance from the inner circumference of the 15 outer ring is always provided on the side of the sawtooth-shaped surfaces which is opposite in the rotation direction.

5. Device according to Claim 4, characterized in that the sawtooth-shaped surfaces which are 20 arranged on the inner circumference of the outer ring of the freewheeling mechanism have a shallow gradient.

6. Device according to any one of Claims 1 to 5, characterized in that the needles of the 25 freewheeling mechanism of the freewheeling bearing are subject to the force of spring bodies in such a manner that they can be pressed onto the sawtooth-shaped surfaces of the outer ring of the freewheeling mechanism, that is to say in the 30 clamping direction.

7. Device according to Claim 6, characterized in that the spring bodies are spring clips which are supported on the outer ring of the freewheeling mechanism of the freewheeling bearing. 35

8. Device according to any one of Claims 1 to 7, chara- terized in that a single-stage spur gearing is connected to the last spur gear/ which ir^tSHf^tCfiff^^perty above the freewheeling bearing on the closCifl&jCQslritiN^ and its spur gear having the largest received .283 74 4 engages with a spur gear which is mounted on the manual tightening shaft and has a small diameter, and in that a freewheeling bearing is furthermore arranged on the manual tightening shaft and holds 5 a bush which is provided with a collar , on whose outer circumference a restoring spring is arranged, one of whose ends is mounted on a stop element , arranged on the bush which is provided with a collar , and the second end of 10 which is mounted on a stop element of two stop elements which are arranged on the rear wall of the circuit breaker drive.

9. Device according to Claim 1, characterized in that the restoring spring is arranged on the shank 15 of the bush which is provided with a collar .

10. Device according to Claim 8 or Claim 9, characterized in that the restoring spring is designed as a rotating spring. 20

11. Device according to any one of Claims 8 to 10, characterized in that the two stop elements which are mounted on the rear wall of the circuit breaker drive are arranged offset with respect to one another through a predetermined angle, preferably of 25 180°.

12. Device according to any one of Claims 8 to 11, characterized in that the manual tightening shaft is mounted at one end in the> rear wall and at the other end in the front wall of the circuit breaker 3 0 drive.

13. Device according to any one of Claims 8 to 12, characterized in that, not only is the backlash angle of the eccentric limited after the closing of the circuit breaker, but the backlash angle of .the catch 35 is also limited after said catch, which is connected to the closing shaft, stops on the closing catch, in that, after the stop element, which is connected to the bush, which is provided with a collar , has stopped 23 DEC 1997 received 28 3 74 4 element which is located first in the rotation direction of the bush and is arranged on the rear wall of the circuit breaker drive, the two stop elements form a non-return stop , together 5 with the freewheeling bearing and the bush, for the single-stage spur gearing, and thus for the closing shaft.

14. Device according to any one of Claims 8 to 13, characterized in that the restoring spring is 10 stressed when the stop element which is connected to the bush stops on the stop element which is located first in f.'.he rotation direction of the bush and is arranges on the rear wall of the circuit breaker drive.

15. 15. Device according to any one of Claims 8 to 14, characterized in that, during the preparation of the circuit breaker for the next closing process by operation of the single-stage spur gearing via the electric motor,/ as a tightening motor, or of the 20 manual tightening shaft, the freewheeling bearing releases the bush which is provided with a collar, so that the bush can be rotated in the opposite direction as a result of the relief of the stress on the restoring spring, until the stop 25 element, which is connected to the bush, stops on the second stop element^ which is arranged on the rear wall of the circuit breaker drive.

16. Device according to any one of Claims 8 to 15, 30 characterized in that the single-stage spur gearing has a high step-down ratio.

17. Device according to any one of Claims 8 to 16, characterized in that the single-stage spur gearing having a high step-down ratio is composed of an 35 elliptical bush which can be fitted onto the shaft of the electric motor and holds on its outer ► circumference, via a ball bearing, an elastic ring which has external teeth and on its major ellipse axis engages in the internal tooth system, whiclftt£|$e<9t5£FP9^ Office of NZ ^ 2 DEC 1997 RECEIVED - -20 - 2 8- 3 7 4 4 concentrically with respect to the shaft of the electric motor, of two rings which are arranged one above the other, one ring Qf whichiis mounted on the housing of the electric motor 5 and the second ring, is fitted with a double spur £T®ar, of which the spur gear -having the smallest diameter engages with the last spur gear arranged on the closing shaft, the elastic ring which has external teeth having fewer teeth them one of 10 the two rings which are provided with an internal tooth system and are arranged one above the other, the other ring which is provided with an internal tooth system having the same number of teeth as the elastic ring which has external teeth. 15

18. A device, as claimed in any one of claims 1-17, substantially as herein described.

19. A device, as claimed in any one of claims 1-17, substantially as herein described and with reference to any one of the Figures. END OF CLAIMS Intellectual Prooertv Office of NZ 23 DEC 1997 Received