EP0174906A1 - Closing device for a circuit breaker with eccentric and unidirectional coupling - Google Patents

Abstract

A drive device for a circuit breaker has a spring which is to be tensioned by a shaft (3). A pinch roller freewheel sits on this as a directional lock. the outer part (52) of which is connected to one or more eccentrics (61, 66) via a band-shaped, flexible traction means (56). The pinch rollers (51) can be pressed out of their working position by cage washers (83). This takes place when the spring (3), which is tensioning the spring, is reached by a release lever (87) in conjunction with toggle levers (95, 96).

Description

The invention relates to a drive device for a circuit breaker with a spring which can be tensioned by a crank pin seated on a shaft by an eccentric member which can be driven all round, a transmission member and a directional lock seated on the shaft.

Drive devices of this type are in many different versions in use, with the aid of a relatively small motor or by hand to tension a relatively strong spring, the energy content of which is sufficient to switch the circuit breaker on and off again. The drive device can act as a jump drive, that is, after switching on the motor, the spring is stretched to the extent that the required energy is available, which is then inevitably released to the switching mechanism, or the drive device can act as a storage drive, in which the stored energy the spring can be released for switching on at any desired time. Such drive devices are manufactured in a very similar design in principle for both low-voltage circuit breakers and medium-voltage circuit breakers. An example of a drive device of the type mentioned can be found in a low-voltage circuit breaker in US Pat. No. 3,301,984. The transmission member is a rod driven by an eccentric crank pin, which acts on the carrier of a drive pawl which can move about the shaft, which engages in the toothing of a ratchet wheel and rotates this step by step as a result of the reciprocating movement of the rod. One with the gear Interacting pawl prevents turning the ratchet wheel back under the influence of the spring to be tensioned. Because of the high demands on the reliability and durability of drive devices of the type considered here, a considerable effort in terms of the accuracy of the interacting parts and their resistance to deformation and wear cannot be avoided. In particular, careful adjustment of the stroke of the transmission link to the pitch of the ratchet wheel is required. If the stroke of the transmission element is too small, the ratchet wheel is not shifted further, while an uneconomical idle stroke occurs if the stroke of the transmission element is too great compared to the pitch of the ratchet wheel. In this case, the toothing of the ratchet wheel and the driving pawl with its bearing are also excessively stressed. Another problem is the transmission element, which on the one hand can prevent the desired placement of certain components of a circuit breaker within the generally very complex overall structure and on the other hand has an unavoidable length tolerance.

It is known in mechanical engineering that a reciprocating movement can be transformed into a stepwise, co-rotating movement using a flexible traction device and a directional lock (FR-A-756 886). Chains are used as traction means, which are guided over sprockets that contain a clamping roller freewheel that serves as a directional lock. The chains are held taut by a spring and a restoring force is applied to the chain wheels.

The object of the invention is to fundamentally eliminate the tolerance problem and the property of a certain bulkiness in drive devices of the type mentioned at the beginning using such a flexible traction means.

According to the invention, this is done in that a flexible traction means connected to the directional lock is used as the transmission member and in that a further eccentric member is seated on the shaft of a hand lever and at least partially wrapped by the traction means between the eccentric member and the directional lock.

In a drive device of the present type, the use of a flexible traction means as the transmission member has the surprising advantage that the transmission members no longer have to be manufactured as dimensionally accurate finished components, possibly with an adjusting device for their effective length, but rather that by choosing a suitable length of the Traction means after the assembly of the other parts a practically tolerance-free adjustment can be made. In contrast to solid rod-shaped transmission elements, the flexibility also allows the force application by a motor and a hand lever to be included in a single or multiple kinked path and thus to achieve a more liberal design in the arrangement of the components of switchgear.

The traction means can be used, for example, in such a way that a section of suitable length is attached at one end to the eccentric and at the other end to the driving part of the directional locking mechanism. In contrast, however, according to a development of the invention, it is advantageous to arrange the traction means of one of the provided eccentric links as an abutment at least partially and to fasten both ends of the traction means to the driving part of the directional lock. In this way, one of the fastening points is omitted, and the wrap-around of the eccentric enables particularly favorable introduction of force into both the eccentric and the traction means. Depending on the chosen guidance of the traction device then lie at least on the driving part of the directional lock, both ends of the traction device one above the other or next to each other.

An additional deflection device for the traction means can be provided in the drive device. The deflection device, which can have the form of a simple roller, allows the traction means to be guided within the circuit breaker in such a way that the space requirement is as small as possible or that other components are bypassed.

The deflection device can be arranged displaceably to act upon the traction means with a driving force. As a result, a further possibility for tensioning the storage spring is available without an additional transmission element.

The losses due to friction can be kept particularly low in a simple manner in a drive device according to the invention in that the eccentrically arranged members and optionally the deflection device are provided as supports for the traction means with the outer ring of a roller bearing. For this purpose, for example, the known needle cages are suitable, the thickness of which is only small, so that the dimensions of the parts to be provided with them are increased only slightly.

As already mentioned, there are traction devices in different embodiments. However, a band-shaped steel sheet is particularly suitable for the purposes of a drive device of the present type, since this material has a very low flexural strength with high tensile strength and does not require any complex elements for lateral guidance. In connection with this, a restoring force is applied to the driving part of the directional locking device in the sense of a tension of the traction means. This tightened the band-shaped steel sheets. This spring has to be added can be overcome by the power source, ie by a motor or by an operator, but it has been shown in practice that the effort for this spring which excites the traction means is extremely small in comparison to the power requirement of the entire device and is therefore negligible.

It has already been pointed out that ratchet wheels in connection with driving pawls and pawls are used as a directional lock in drive devices for circuit breakers. In the context of the invention, however, it is particularly advantageous to provide a pinch roller freewheel or a sprag freewheel as a directional lock. Such freewheels are generally known as machine elements, compare, for example, a catalog from Stieber Präzision GmbH, pages 5, 6, 14 and 15. Since such freewheel clutches, in contrast to ratchet ratchets, are not tied to a specific angle of rotation, one only has it in hand to achieve larger or smaller switching steps of the directional lock by a different eccentricity of the eccentrics driving the traction means. The directional lock itself does not require any change. In this context, it is advisable to use the same pinch roller freewheel or sprag freewheel as a lock against reverse rotation of the shaft.

In connection with the clamping roller or clamping body freewheel, the clamping rollers or the clamping bodies can be moved into an ineffective position by at least one actuator depending on the end position of the shaft. Pinch roller freewheels with uncouplable pinch rollers are known per se (DE catalog "Freewheels", Fa. Stieber Präzision GmbH, page 75).

• Die Figur 1 zeigt eine Antriebsvorrichtung nach der Erfindung in einem Längsschnitt und teilweise in Ansicht, wobei die Schnittebenen von zwei Schnitten sowie die Richtung der Ansicht einer Einzelheit eingetragen sind.
• Die Figur 2 ist ein Schnitt der Antriebsvorrichtung gemäß der Figur 1 in der Ebene II - II.
• Die Figur 3 ist ein Schnitt durch die Antriebsvorrichtung gemäß der Figur 1 in der Ebene III - III.
• In der Figur 4 ist eine Einzelheit der Antriebsvorrichtung gemäß der Figur 1 entsprechend dem Pfeil IV dargestellt.

The slight angular rotation which the shaft travels after the dead center of its crank pin connected to the spring to be tensioned until it is blocked by a releasable stop can expediently be used for this purpose. The invention is explained below with reference to the embodiment shown in the figures.

• Figure 1 shows a drive device according to the invention in a longitudinal section and partially in view, the sectional planes of two cuts and the direction of the view of a detail are entered.
• Figure 2 is a section of the drive device according to Figure 1 in the plane II - II.
• FIG. 3 is a section through the drive device according to FIG. 1 in the plane III-III.
• FIG. 4 shows a detail of the drive device according to FIG. 1 in accordance with arrow IV.

In FIG. 1, two walls 1 and 2, shown at a distance from one another and broken off, are shown, which are part of a low-voltage circuit breaker. A shaft 3 is mounted in the bearing openings of these walls, on which a cam disk 4 (see FIG. 2) is fastened in a rotationally locking manner. In a known manner, the cam disc 4 serves to move into the switch-on position in cooperation with a roller 5 lying on its periphery in FIG. This is done with the aid of a lever mechanism which can best be seen in FIG. 2, which includes toggle levers 7 and 8, a support rocker arm 10, an intermediate lever 11 and a crank rocker 13 or a plurality of crank rockers seated on a selector shaft 12. The roller 5 is attached to the lower toggle lever 7 rotatable about a fixed bearing 14. It could, for example, also be attached to the knee joint pin 15, which connects the toggle levers 7 and 8 to one another in an articulated manner. On the connecting joint 21 of the upper toggle lever 8 and the intermediate lever 11, the support rocker 10 engages, the other end of which is articulated on a ratchet lever 16 is. The pawl lever 16 is in turn supported on a trigger shaft 17.

If the cam plate 4 is rotated starting from the position shown in the direction of arrow 20, the toggle levers 7 and 8 are stretched, the intermediate lever 11 being displaced simultaneously via the joint 21 and the crank arm 13 being rotated clockwise by the joint 22 via the joint 22. The joint 21 is guided by the support rocker 10 on a circular arc around the joint 23 located on the ratchet lever 16. If, starting from the switch-on position, the trigger shaft 17 is rotated clockwise to such an extent that the ratchet lever 16 loses its hold, then the ratchet lever 16 becomes under the influence of the load on the joint 21, which is transmitted to the ratchet lever 16 via the support rocker 10 Pivoted clockwise around the fixed bearing 24. This leads to the opening of the contact lever 6 by turning the selector shaft 12 counterclockwise.

In the following, FIG. 1 is first considered further. This shows that the shaft 3 is not directly supported with its surface in bearing openings of the walls 1 and 2, but with the insertion of bush-like parts which belong to two pinch roller freewheels 18 and 19. At the left end of the shaft 3, the inner part 31 of a clamping roller freewheel 18, which rests on the shaft like a sleeve, is fastened by means of a screw 30, the outer end face of which carries an eccentrically arranged driving pin 32 for the spring 33 to be tensioned. This is shown broken off in FIG. 4, which shows a view of the pinch roller freewheel 18 according to FIG. 1 in the direction of arrow IV. The inner part 31 is provided with two axially juxtaposed shoulders of different diameters running concentrically to the longitudinal axis of the shaft 3. The peripheral surfaces 34 and 35 formed in this way are overlapped by the outer part 36 of the freewheel 18, which is firmly connected to the wall 1. To shoot Oeren mounting of the shaft 3, a needle cage 40 is arranged between the peripheral surface 35 of the inner part 31 and an inner surface 37 of the outer part 36, whereby a rolling bearing is formed. Between the inner circumference 41 of the outer part 36 and the circumferential surface 34 of the inner part 31 there are a plurality of clamping rollers 42 in recesses 38 (FIG. 1) with a shape typical of pinch roller freewheels, which only allow the shaft 3 to rotate in a known manner.

A further pinch roller freewheel 19 is assigned to the end of the shaft 3 on the right in FIG. 1, which has parts similar to the pinch roller freewheel 18 but with additional functions. In particular, a driving force is introduced into the pinch roller freewheel 19, and a device is provided to arbitrarily release the clutch between the outer and the inner part of the pinch roller freewheel 19. For this purpose, the clamping roller freewheel 19 in turn has an inner part 45 which, apart from somewhat different dimensions, corresponds in principle to the inner part 31 and which is likewise connected to the shaft 3 by means of a screw 46. A bushing 47 fitted into the side wall 2 and a needle cage 50 serve to mount the inner part 45 in the side wall 2. Furthermore, corresponding clamping rollers 51 are provided for the clamping rollers 42, each of which is compressed by a compression spring 57 in FIG. 3 into the narrowing part of recesses 58 in FIG 3, which are located on the inner circumference 53 of the outer part 52. In contrast, the outer part 52 of the freewheel 19 is designed differently because of the additional functions. On the inner circumference 53 of the outer part 52, recesses 58 are first provided in a known manner for the clamping rollers 51, the radial height of which is different in such a way that the clamping rollers rotate in one direction between the inner circumference 53 of the outer part 52 when the arrangement is rotated and the peripheral surface 54 of the inner part 45 are clamped in place and no coupling occurs when rotating in the reverse direction.

With regard to the further features of the clamping roller freewheel 19 just described, reference is also made to FIG. 3, which represents a section of the arrangement according to FIG. 1 along the plane III-III. As can be seen, the outer part 52 of the freewheel 19 is provided with an extension 55 to enlarge the effective lever arm, which extends over part of the circumference of the outer part 52 and forms a concentrically running contact surface for a flexible steel band 56, which is provided as a traction means .

Before a further explanation of the pinch roller freewheel 19 located at the right end of the shaft 3 in FIG. 1, the arrangement of this traction means 56 is first considered with reference to FIG. The traction means 56 wraps around the outer ring 60 of a rolling bearing at an angle of slightly more than 180 ^* , the inner ring of which is formed by an eccentric 61. This is attached to the shaft 62 of a hand lever 63. The shaft 62 is mounted in the housing 68 of the low-voltage circuit breaker, which is shown schematically in part. The two ends 64 and 65 also loop around another eccentric 66, which is fastened on a shaft 67. The shaft 67 can be the shaft of a motor 70 or an intermediate gear connected downstream of the motor 70. The outer ring 71 of a rolling bearing is in turn inserted between the traction means 56 and the eccentric 66. In the space between the eccentric 66 and the shaft 3, a deflection device for the traction means 56 is arranged, which consists of a stationary bolt 72 and a further outer ring 73 of the roller bearing. The two ends 64 and 65 of the traction means 56 lie one above the other on the extension 55 of the outer part 52 and are firmly connected to the outer part 52 by means of a slotted clamping pin 74. A projection 75 of the outer part 52 which receives the clamping pin 74 also contains an opening 76 for hanging in a tension spring 80, for the other end of which a pin 81 which is fixedly connected to the housing 68 is provided as an abutment. The tension spring is expediently dimensioned such that the tension element tel 56 is taut and thus tangent to the rolling rings 60, 71 and 73 and to the approach 55.

If, for example, the eccentric 66 is rotated by means of the shaft 67, the traction means 56 is moved periodically by the amount of the eccentricity of the eccentric 66. This movement manifests itself in cooperation with the spring 80 in an alternating clockwise and counterclockwise pivoting of the outer part 52. Here, the traction means 56 acts because of the concentric shape of the extension 55 with a constant lever arm. The pivoting of the outer part 52 clockwise causes the shaft 3 to also rotate clockwise by means of the pinch rollers 51.

As a result, the spring 33 (Figure 4) is tensioned accordingly. The clamping position reached in each case is maintained by the clamping roller freewheel 18 located at the left end of the shaft 3 and already described. As a result, when the outer part 52 is subsequently pivoted counterclockwise, the shaft 3 can maintain its position. With this idle stroke, the pinch rollers 51 slide on the outer surface 54 of the inner part 45.

In the process described above, the traction means 56 is supported on the eccentric 61 of the hand lever 63. In the same way, a gradual tensioning of the spring 33 (FIG. 4) can now be effected by means of the eccentric 61 via the hand lever 63, the eccentric 66 acting as an abutment and the rolling ring 71 thereon acting as a deflection roller. The greatest possible tension of the spring 33 is reached when the eccentric bolt 32 is in the dead center position. If no special precautions are taken, the bolt 32 exceeds its dead center position, and the spring 33 relaxes with a corresponding rotation of the cam plate 4 to switch on the circuit breaker. In this embodiment, the drive device makes a jump drive. However, if the drive device should act as a storage drive, it is necessary to maintain the tensioned state of the spring 33 until a desired point in time. For this purpose, it is common to provide a releasable stop against which the bolt 32 lies when it has exceeded its dead center position by a small amount. The representation and description of the parts belonging to such a device can be dispensed with in the present context, since these are generally known features. However, the parts of a device which serve to prevent further transmission of the drive force to the shaft 3 after it has reached the end position when the spring 33 is tensioned are described below. For this purpose, cage disks 83 are arranged on both sides of the outer part 52 and are provided on their inner circumference with recesses 84 which overlap the clamping rollers 51. By rotating the cage washers 83 relative to the outer part 52, all the clamping rollers 51 can thus be pressed out of their working position at the same time, in which they establish a non-positive connection between the outer part 52 and the inner part 45. This occurs after the dead center position of the bolt 32 is exceeded in that a cam 85 attached to the inner part 45 runs against a nose 86 of a two-armed release lever 87, which is pivotably mounted on a pin 90 and, in the normal state, is applied to a stop 92 by a tension spring 91 is. The longer leg 88 of the release lever 87 facing away from the nose 86 is curved on its inner flank in order to achieve a smooth interaction with a roller 93 which is seated on the knee joint pin 94 of toggle levers 95 and 96. The toggle lever 95 is articulated to the outer part 52, while the toggle lever 96 engages discs 83 on the cage 10. In the normal position of the release lever 87, the toggle levers 95 and 96 are buckled, the pinch rollers in the recesses 84 being freely movable and their function not being affected as a result.

If the cam 85 now runs against the nose 86 of the release lever 87, it is pivoted clockwise about its bearing pin 90, the leg 88 of the release lever 87 acting on the roller 93 and bringing the toggle levers 95 and 96 into their extended position. This is associated with a rotation of the cage disks 83 by an angle sufficient to take the pinch rollers 51 with them, whereby a flow of force is interrupted from the outer part 52 to the inner part 45. The traction means 56 is thus decoupled from the driving force, irrespective of whether this was initiated by the motor 70 or the hand lever 63. As can be seen, the longer leg 88 of the release lever 87 is provided with a bend 89 so that the leg 88 can move past the traction means 56 and cooperate with the roller 93 which is centered with respect to the traction means.

The advantages that can be achieved by the use of a traction device in drive devices for circuit breakers can be seen from FIG. 3. In particular, there is extensive freedom of movement in the spatial assignment of the components to be connected to one another. Assuming, for example, a predetermined position of the shaft 3 within the housing 68, it would be no problem to change the position of the shafts 62 and 67 and also the deflection device (parts 72, 73) significantly. The traction means 56 can be adapted to these conditions simply by taking a corresponding length from a supply without tolerance. If, instead of the band-shaped traction means used in the example described, a rope-shaped traction means were provided, it would also be possible to connect shafts to one another which, in contrast to the example, are at an angle to one another.

It has already been mentioned that a traction means is in principle also suitable for operating a directional ratchet that works with tie and pawls. The advantage is already gained here that the length tolerances that occur with push rods or drive rods are eliminated. One could also think of combining a push rod with a pinch roller freewheel. This would make it possible to achieve a larger range of step angles of the shaft to be driven, since there is no dependence on a specific angular division, as is the case with ratchet wheels. The combination of the flexible traction device described above with a pinch roller freewheel, however, has the special property that any dead gear is avoided and thus the lifting movement of the eccentrics 61 and 66 is completely converted into a pivoting of the outer part 52. Furthermore, there are no sudden stresses on all interacting parts, which is noticeable in a quieter gear of the drive device and an increased service life.

Claims (7)

1. Drive device for a circuit breaker with a spring (33) by a crank pin (32) seated on a shaft (3) by an all-round drivable eccentric member (eccentric 66), via a transmission member and a seated on the shaft (3) Directional lock (19) can be tensioned, characterized in that a flexible traction means (56), which is connected to the directional lock (19), serves as the transmission member, and that another, on the shaft, between the eccentric link (eccentric 66) and the directional lock (19) (62) of a hand lever (63) seated and at least partially wrapped by the traction means (56) eccentric member (eccentric 61) is arranged. 2. Drive device according to claim 1 or 2, characterized in that the traction means (56) of one of the eccentric members (eccentric 61, 66) as an abutment is arranged at least partially looping and both ends (64, 65) of the traction means (56) on the driving part (52) of the directional lock (19) are attached. 3. Drive device according to claim 1 or 2, characterized in that an additional deflection device (72, 73) for the traction means (56) is seen. 4. Drive device according to claim 3, characterized in that the deflection device (72, 73) is arranged to act upon the traction means (56) with a driving force. 5. Drive device according to one of the preceding claims, characterized in that that the eccentric members (eccentric (61, 66) and possibly the deflection device (72, 73) are provided as supports for the traction means (56) with the outer ring (71, 60, 73) of a roller bearing. 6. Drive device according to claim 1, characterized in that a band-shaped steel sheet (56) is used as the traction means and that a restoring force (spring 80) acting on the driving part (56) of the directional lock in the sense of a tension of the traction means (56) is provided. 7. Drive device according to claim 1, characterized in that a clamping roller freewheel (19) or clamping body freewheel serves as a directional lock and that the clamping rollers (51) or clamping body by at least one actuator (83, 87) depending on the end position of the shaft (3rd ) can be moved into an ineffective position.

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