EP0658909B1 - Drive mechanism for a power circuit breaker - Google Patents

Abstract

The drive device has a cam disc (18) which can be driven in a pulsed manner in a rotational direction (D) by means of an energy store in order to connect the power circuit breaker. An intermediate section (50) having a continuously reducing radius is adjacent to a first section (48) of the cam track (20) of the cam disc (18), in which first section (48) the radius increases as the azimuth angle increases counter to the rotational direction (D). This intermediate section (50) is followed by a second section (52) which runs approximately in the radial direction. As a result of the interaction of the first section (48) with the roller (22'), the triangular lever (76) is moved, together with the switching shaft (26), counter to the rotation direction (D) from the disconnected position into the connected position, and through an excess travel (U) beyond this point. When the intermediate section (50) moves past the roller (22'), the triangular lever (76) moves slowly back in the rotational direction (D) as a result of the force of the disconnection spring, which is now stressed, until its latching tab (78) rests against the connection latch (72). This slow backward movement results in the impact forces which act on the latch (34) being greatly reduced. <IMAGE>

Description

The present invention relates to a drive device for a circuit breaker, in particular for medium and high voltage, according to the preamble of claim 1.

A drive device of this type is disclosed in DE-A-25 17 134. On a shaft rotatably mounted about its axis, on which an energy storage device designed as a tension spring acts eccentrically, a cam is seated in a rotationally fixed manner, the cam track of which has a first section, the radius of which increases steadily with increasing azimuth against the direction of rotation of the shaft. At the rear end of the first section in the direction of rotation, there is a second section running approximately in the radial direction with an abruptly decreasing radius, to which a third section adjoins the direction of rotation, which extends to the beginning of the first section and has a radius that corresponds approximately to the radius at the beginning of the first section.

A switching shaft connected to the movable contact of the circuit breaker is arranged parallel to the shaft and on it there sits a disk in a rotationally fixed manner, from which a peg-like follower projects eccentrically with respect to the axis of the switching shaft. The shaft is also connected to an opening spring. On its circumference, the disk has a latching recess which is intended to cooperate with an opening pawl of a pawl device.

To tension the closing spring, the shaft is rotated in the direction of rotation beyond the unstable dead center and held there supported by a closing pawl. To switch the switch on, the release pawl is released, causing the shaft to rotate in the direction of rotation due to the force of the switch-on spring. The cam section runs with its first section on the follower and swivels the switching shaft from its switch-off position to the switch-on position and by an overtravel as it rotates further. This overstroke is generally necessary to ensure that the latching device engages. As soon as the first section of the curve spell starts running from the following link, the switch-off spring accelerates the selector shaft until it is in contact with the switch-off pawl. The pawl device therefore not only has to support the force of the switch-off spring, but also has to absorb the additional impact stress caused by striking the switch-off pawl. For switching on and simultaneous tensioning of the switch-off spring, the shaft rotates by approximately 180 °, the excess energy being recuperated into the switch-on spring by turning beyond the stable dead center position.

Another drive device of the generic type is disclosed in CH-A-498 480. A cam disk which can be rotated in the direction of rotation by 360 ° by means of switch-on springs for switching on the switch has a cam track with a first and a second section. The radius of the first section increases with the azimuth increasing counter to the direction of rotation, spiraling over an angle of almost 360 °. Between the At the end of the first section with the largest radius and its beginning, the abruptly falling second section extends approximately in the radial direction. A follower designed as a roller cooperates with the cam disc, which is mounted on one end of a two-armed lever, the other end of which is intended to interact with a latching device and which is connected to the movable contact of the circuit breaker and an opening spring. Due to the pulse-like rotation of the cam disc by 360 °, the lever is moved from its switch-off position from the first section, while simultaneously switching on the switch and tensioning the switch-off spring, into the switch-on position and beyond. If the first section runs from the follower, the switch-off spring accelerates the lever in the opposite direction until it is in contact with the latch device. Here too, in addition to the force of the opening spring, the pawl device also has to absorb the dynamic force due to the lever being opened.

In both known drive devices, the pawl device must therefore be appropriately large. This requires considerable space and leads to large masses that have to be moved to unlatch. Moving these large masses in turn requires high drive powers of the latch device or leads to slow unlatching.

A drive device having a cam disk, which has a different structure and a different mode of operation compared to the two aforementioned drive devices, is disclosed in EP-A-0 150 756.

A roller-like follower interacting with the cam track of the cam is arranged on a lever that is operatively connected to the closing spring. The cam track of the cam disk, which can be driven in the direction of rotation by means of a motor or by hand, has a first section with an increasing azimuth opposite to the direction of rotation. Contrary to the direction of rotation, a section adjoins this first section with an increasing azimuth, gradually decreasing radius, to which in turn adjoins a second section running essentially in the radial direction, followed on the inside by the first section. When the closing spring is relaxed, the next link is at the beginning of the first section. The closing spring is tensioned by slowly rotating the cam disc in the direction of rotation by a little less than 360 ° until the end of the first section. When the follower interacts with the following section with a slowly decreasing radius, the closing spring drives the cam disc in the direction of rotation. However, the cam disc now uncoupled from the engine is prevented from turning further by means of a ratchet device. To turn on the circuit breaker connected to the drive device, the pawl device is energized to release the cam. This begins to rotate under the force of the closing spring acting via the lever and the follower reaches the abruptly falling second section, so that the cam disc no longer exerts any counterforce against the action of the closing spring. Under the force of the closing spring, the follower is suddenly accelerated while simultaneously switching on the switch and tensioning an opening spring. With this drive device, the cam disc becomes Tensioning the closing spring is used and it also acts as a ratchet ratio. Furthermore, it is necessary in this known drive device to decouple the switch and the switch-off spring from the switch-on spring by means of a special device after switching on.

It is an object of the present invention to provide a generic drive device with a small load on the ratchet device, so that it can be built lighter and taking up less space.

This object is achieved by a generic drive device which has the features in the characterizing part of claim 1.

Since the follower lies against an intermediate section of the cam track until it is supported on the pawl device, the pawl device runs onto it at a low speed, so that the dynamic impact forces are considerably reduced or even avoided. The pawl device can thus be dimensioned for the static force effect of the opening spring and the reduced dynamic impact forces, which enables a light, space-saving construction of the pawl device and the entire drive device. Since the moving masses of the pawl device can be kept small, quick unlatching takes place and / or less work is required for the unlatching.

A particularly preferred embodiment of the drive device according to the invention enables the acceptance of large tolerances.

Another preferred embodiment of the drive device according to the invention is specified in claim 3. It enables the first and second sections of the curved path to be formed in a smaller azimuth range than if there were a further section with a constant radius between the first section and the intermediate section.

Further particularly preferred embodiments of the device according to the invention are specified in the remaining claims.

Fig. 1

perspektivisch und vereinfacht eine erfindungsgemässe Antriebsvorrichtung;

Fig. 2

eine Ansicht der Kurvenscheibe der erfindungsgemässen Antriebsvorrichtung in Richtung des Pfeiles II der Fig. 1;

Fig. 3

stark vereinfacht die Kurvenscheibe, den das mit der Kurvenscheibe zusammenwirkende Folgeglied tragenden Hebel und die Klinkenvorrichtung der erfindungsgemässen Antriebsvorrichtung in Ausschaltstellung;

Fig. 4

die in der Fig. 3 gezeigten Komponenten der Antriebsvorrichtung zu Beginn eines Einschaltvorgangs;

Fig. 5

die in der Fig. 3 gezeigten Komponenten der erfindungsgemässen Antriebsvorrichtung während des Einschaltvorgangs bei maximaler Auslenkung des Hebels; und

Fig. 6

die in der Fig. 3 gezeigten Komponenten der Antriebsvorrichtung am Ende des Einschaltvorgangs.

The invention will now be explained in more detail with reference to the drawing. It shows purely schematically:

Fig. 1

perspective and simplified a drive device according to the invention;

Fig. 2

a view of the cam of the drive device according to the invention in the direction of arrow II of FIG. 1;

Fig. 3

greatly simplifies the cam, the lever carrying the follower interacting with the cam and the pawl device of the drive device according to the invention in the switched-off position;

Fig. 4

the components of the drive device shown in Figure 3 at the beginning of a switch-on.

Fig. 5

the components of the drive device according to the invention shown in Figure 3 during the switch-on process with maximum deflection of the lever. and

Fig. 6

the components of the drive device shown in FIG. 3 at the end of the switch-on process.

The drive device 10 shown in FIG. 1 for driving a circuit breaker 12 for medium or high voltage, which is only indicated schematically, has a shaft 16, which is freely rotatably mounted on a frame 14 in a known manner and on which a cam disk 18 is seated in a rotationally fixed manner. The outer surface of the cam 18 forms a cam track 20, which cooperates with a roller 22 'acting as a follower 22. The roller 22 'is freely rotatably mounted on the free end of a lever 24 which is non-rotatably seated on a control shaft 26 parallel to the shaft 16. The control shaft 26 is also freely rotatably mounted on the frame 14 and connected to the moving contact piece 30 of the circuit breaker 12 via a linkage 28. On the selector shaft 26 there is also a pawl lever 32, which is intended to cooperate with the pawl 34 supported on the frame 14 in the switch-on position I shown in dash-dotted lines. The pawl 34 can be pivoted by means of an electric switch-off magnet 36 to release the pawl lever 32 and thus the switching shaft 26 from a support position into a release position. The pawl lever 32, the pawl 34 and the electric switch-off magnet 36 form a pawl device 37.

A switch-off spring 38 designed as a helical compression spring is supported on one end on the frame 14 and is connected at the other end to a pulling element 40 designed as a chain, which deflects around a deflection wheel 42 which is freely rotatably mounted on the frame 14 and is articulated on the other side to a drive lever 44 which is non-rotatably seated on the control shaft 26 is. If the control shaft 26 is rotated into the on position I, the drive lever 44 extends approximately at right angles to the direction of attack of the pulling element 40; in the off position O of the control shaft 26, the direction of engagement of the pulling element 40 is almost in the extended position relative to the drive lever 44.

For the sake of completeness, it should be mentioned that the control shaft 26 is connected to a damping element 46 in order to dampen the rotary movement of the control shaft 26 towards the end of a switch-off process.

As can be seen in particular from FIG. 2, the cam track 20 of the cam disc 18 has a first section 48 which has a constantly increasing radius A when the azimuth α increases counter to the direction of rotation indicated by an arrow D. In the present example, the first section 48 extends through an angle 48 ″ of approximately 155 °. At the end 48 'of the first section 48 with the maximum radius A, as seen against the direction of rotation D, there is an intermediate section 50, the radius A of which decreases steadily and slowly with increasing azimuth α. The intermediate section 50 extends over an angle 50 'of preferably 10 ° -20 °, in the present case of approx. 17 °, and the radius decreases in it A by an amount B which is approximately 0.2 to 5%, preferably 0.5 to 1.5% of the difference between the minimum radius A _min at the beginning of the first section 48 and the largest radius A _max at the end 48 ' of the first section 48.

Contrary to the direction of rotation D, the intermediate section 50 is adjoined by a second section 52 which is concavely curved with a radius that is larger than the radius of the movement path of the follower 22 and whose end region adjoining the intermediate section 50 extends approximately in the radial direction. In the example shown, the second section 52 extends over an angle 52 ′ of approximately 57 °. This second section 52 enables the switching shaft 26 to be turned from the on position I to the off position O without the follower 22 touching the cam plate 18 (see also FIG. 6).

Contrary to the direction of rotation D, the second section 52 is adjoined by a third section 54 with a radius A which corresponds to the minimum radius A _min at the beginning of the first section and which extends over an angular range 54 ′ to the beginning of the first section 48.

A large wheel 56 of a toothed pair of wheels 58, the small wheel 60 of which is connected to an elevator motor 64 via a gear 62, also sits on the shaft 16 in a rotationally fixed manner. A preferred embodiment of this pair of wheels 58 is disclosed in European Patent Application No. 93 117 797.6.

On the big wheel 56 is, with respect to the axis 16 'of the shaft 16 is eccentrically articulated, a chain forming a tension element 66, which is guided around a further deflection wheel 42 'which is rotatably mounted on the frame 14 and is operatively connected at the other end to a closing spring 68. This is designed as a helical compression spring and is also supported on the frame 14; it forms an energy store 68 '.

Furthermore, a locking pin 70 is fastened to the large wheel 56, which interacts with a switch pawl 72 mounted on the frame 14. This is connected to an electric switch-on magnet 74, by means of which the switch pawl 72 can be retracted from a support position, in which it engages in the movement path of the locking pin 70, into a release position. The latching pin 70, the catch pawl 72 and the electrical switch-on magnet 74 form a switch pawl device 75 and furthermore rotatable, after which the locking pin 70 runs further by an angle of a few degrees after reaching the unstable dead center position on the engagement pawl 72 and is held against it under the action of the tensioned engagement spring 68. The elevator motor 64 is switched off after the unstable dead center position has been exceeded. With the large wheel 56 supported, the cam disc 18 assumes a position in which the follower 22 brought into the switch-off position O comes to rest at the beginning of the first section 48, as shown in FIG. 3. This figure and the further FIGS. 4-6 show the cam plate 18, a lever 24 and the pawl lever 32, on the selector shaft 26 seated triangular lever 76 on which the roller 22 'is freely rotatably mounted, and the pawl 34 of the pawl device 37. The pawl nose which cooperates with the pawl 34 and corresponds to the pawl lever 32 (FIG. 1) is denoted by 78.

5, the dash-dotted segment 80 of a circle about the axis 16 'of the shaft 16 indicates that radius A _k which corresponds to the position of the follower 22 or the roller 22' when the triangular lever 76 with its pawl nose 78 on the Pawl 34 abuts; this is the switch-on position. The segment 80 crosses both the first section 48 and the intermediate section 50 of the curved track 20. The double arrow U denotes an overstroke which is given by the difference between the largest radius A _{max of} the first section 48 of the curved track 20 and the radius A _k .

Finally, in FIG. 6, a further segment 82 of a circle, indicated by dash-dotted lines, around the axis 26 'of the shift shaft 26 shows the range of motion of the roller 22' when shifting.

The mode of operation of the drive device 10 is explained below with reference to FIGS. 1 to 6. 1 and 3, the drive device 10 is shown with the closing spring 68 tensioned and the switching shaft 26 in the off position O. To turn on the circuit breaker 12 and simultaneously tension the opening spring 38, the electric closing magnet 74 is briefly energized, as a result of which the closing pawl 72 releases the latching pin 70 and the shaft 16 together with the cam plate 18 underneath Force of the closing spring 68 begins to turn in direction D. The cam 18 runs onto the roller 22 'and, in cooperation with the first section 48 of the cam track 20, rotates the triangular lever 76 and thus the selector shaft 26 in the switch-on direction E, which is opposite to the direction of rotation D (FIG. 4). The circuit breaker 12 is closed and the opening spring 38 is tensioned. The pawl nose 78 pushes the pawl 34 back out of its support position in a clockwise direction, which engages behind the pawl nose 78 by turning back into the support position as soon as the cam 18 has reached the position at which the point of intersection of the first section 48 of the curve 20 with the segment 80 passes the roller 22 '. As shown in FIG. 5, the triangular lever 76 is moved by an excess stroke U beyond the switch-on position in order to ensure that the pawl device 37 is latched under all conditions. This position is reached when the end 48 'of the first section 48 with the radius A _{max interacts} with the roller 22'. In this position of the shaft 16, the articulation of the tension element 66 is preferably at least approximately in the stable dead center position. When the cam 80 continues to rotate in the direction of arrow D, owing to the kinetic energy still present, the intermediate section 50 interacts with the roller 22 ', as a result of which the switching shaft 26, which is under the force of the tensioned opening spring 38, counteracts the closing direction E in accordance with the intermediate section 50 moved back until the pawl nose 78 abuts the pawl lever 76. This is achieved at the rotational position of the cam plate 18 at which the intersection of the intermediate section 50 with the segment 80 lies against the roller 22 '. 6 shows The cam 18 rotates further out of the swivel range of the roller 22 ', so that the circuit breaker 12 can now be switched off again at any time by activating the electrical switch-off magnet 74 by the force of the switch-off spring 38. When the dead center position 66 'is reached, the kinetic energy of the masses moving together with the shaft 16 is recuperated during rotation beyond the stable dead center position 66' by the partial tensioning of the closing spring 68. The energy given off by the switch-off spring 38 to the cam plate 18 via the intermediate section 50 is also recuperated into the switch-on spring 68. A backward rotation in the direction of rotation D is prevented by means of a backstop in the gear 62. To fully tension the switch-on spring 68, the elevator motor 64 is now switched on until the unstable dead center position is exceeded and the locking pin 70 is again in contact with the switch pawl 72. When the closing spring 68 is tensioned, the third section 54 moves past the movement path 82 of the follower 20 ′, so that the circuit breaker 12 can be switched off at any time. The drive device 10 is now ready for the circuit breaker 12 to be switched on again immediately.

The decrease in the radius A of the intermediate section 50 of the cam track 20 is matched with respect to the corresponding rotational speed of the shaft 16 such that the pawl nose 78 runs onto the switch-off pawl 34 at a low speed. In any case, the triangular lever 76 is supported by the cam 18 until it contacts the switch-off pawl 34.

It should be mentioned that the cam disk 18 shown in FIG. 2 together with the specified angles and radii is only to be understood as an example and that both the angles and the radii can vary considerably. Thus, the shape of the cam 18 according to the invention can also be used in a drive device in which the cam disk is rotated through 360 ° to switch on the circuit breaker, as is the case with the drive device disclosed in CH-A-498 480. The first section of the cam track with a steadily increasing radius and the intermediate section with a slowly steadily decreasing radius extend together over an angle of almost 360 °, so that the second section, which runs essentially in the radial direction, ensures that the follower is switched off of the circuit breaker can move past the cam 18.

In the example shown in the figures, the intermediate section preferably extends over an angle 50 'of between 10 and 20 °. However, it is also conceivable that this angle, in particular in the case of a switching device in which the cam disk rotates through 360 ° to switch on the circuit breaker, is greater than 20 °. In any case, the decrease B in the radius in the intermediate section 50 is at least the same size, preferably greater than the overstroke U.

Claims (6)

1. Drive device for a power switch, in particular for medium and high voltage, having a cam disc (18), which, for switching on the power switch (12), can be driven by means of an energy store (68') about an axis (16') in a direction of rotation (D) and the curve path (20) of which exhibits a first section (48) of radius (A), which increases as the azimuth (α) increases counter to the direction of rotation (D), and a second section (52), which follows behind the first section (48) in the direction of rotation (D) and runs roughly in the radial direction, having a follow-up member (22, 22'), which is forced by a disconnecting spring (38) in the direction of the cam disc (18) and which, by rotation of the cam disc (18) in the direction of rotation (D), by means of the first section (48) of the curve path (20), is moved from a switch-off setting (0), as the disconnecting spring (38) is simultaneously tensioned, into a switch-on setting (I) and by a measure of an overtravel (U) beyond this, and which is designed to be connected to a moved contact piece (30) of the power switch (12), and having a pawl (34) for the releasable supporting of the follow-up member (22, 22') in the switch-on setting (I) after the first section (48) has run off from the follow-up member (22, 22'), characterized in that the curve path (20) exhibits, between the, in the direction of rotation (D), trailing end (48') of the first section (48) and the second section (52), an intermediate section (50) of a radius (A) which becomes steadily smaller as the azimuth (α) increases, against which intermediate section (50) the follow-up member (22, 22') bears until supported against the pawl (34).
2. Device according to Claim 1, characterized in that the reduction (B) in the radius (A) of the curve path (20) in the intermediate section (50) is larger than the overtravel (U).
3. Device according to Claim 1 or 2, characterized in that the intermediate section (50) adjoins the first section (48).
4. Device according to one of Claims 1 to 3, characterized in that the intermediate section (50) sweeps an angle (50') of 10 to 20°.
5. Device according to one of Claims 1 to 4, characterized in that the reduction (B) in the radius (A) of the curve path (20) in the intermediate section (50) measures 0.2 to 5%, preferably 0.5 to 1.5%, of the difference between the largest and smallest radius (A_max; A_min) of the first section (48).
6. Device according to one of Claims 1 to 5, characterized in that the energy store (68') exhibits a connecting spring (68) connected to the one end of a traction element (66), which, eccentrically attached in an articulated manner by its other end to the axis (16') of the cam disc (18), is connected to the latter, and the trailing end (48') of the first section (48) of the curve path (20) interacts with the follow-up member (22, 22') whenever the articulated attachment of the traction means (66) is located at least approximately in the stable dead centre position (66').

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