Tap changer, force-storage unit, and controlled-backlash coupling therebetween

Abstract

An energy accumulator (15) for or in an on-load tap changer (10) comprises a motor (11) with an output shaft (12) and a load diverter switch (13) with an input shaft (14), comprising an elastic storage element (17); a transmission coupled to the storage element (17) and having an input hub (201) that can be rotationally fixed to the output shaft (12); an output hub (231) that can be rotationally fixed to the input shaft (14); and a variable transmission (20, 21) interposed between the input hub (201) and the storage element (17).

Claims

1. In combination with an on-load tap changer having a motor with an output shaft and a load diverter switch with an input shaft, an energy accumulator comprising an elastic storage element; a drive train coupled to the storage element and having an input hub that can be rotationally fixed to the output shaft; an output hub that can be rotationally fixed to the input shaft; a variable transmission interposed between the input hub and the storage element; a first coupling that has a predetermined first angular backlash and that is between the input hub and the storage element; and a second coupling that has a predetermined second angular backlash and that is between the storage element and the output hub.

2. The energy accumulator according to claim 1, further comprising a tensioning and relaxing element in operative engagement with the storage element for tensioning the storage element upon rotation of the input hub and for driving the output hub upon relaxation of the storage element, the drive train being formed such that it rotates with the tensioning element at a specified velocity upon relaxation of the relaxing element; and/or restresses the relaxing element on relaxation of the relaxing element.

3. The energy accumulator according to claim 1, wherein the drive train is formed so as to tension the storage element upon rotation of the input hub in a first direction from a predetermined first angular position into a predetermined second angular position, while the output hub is stationary; and the storage element is formed so as to relax upon rotation of the input hub in the first direction from the second angular position into a predetermined third angular position, and the output hub meanwhile rotates from another first angular position into another second angular position.

4. The energy accumulator according to claim 3, wherein the drive train is formed such that the transmission ratio of the variable transmission upon rotation of the input hub in the first direction from the second into the third angular position is smaller than during tensioning.

5. The energy accumulator according to claim 3, wherein the drive train is formed such that the transmission ratio of the variable transmission upon rotation of the input hub in the first direction from the first into the second angular position is greater than a specified threshold value; and the transmission ratio of the variable transmission upon rotation of the input hub in the first direction from the second into a third angular position is smaller than the threshold value.

6. The energy accumulator according to claim 3, wherein the drive train and the storage element are formed such that together they rotate or can rotate the output hub from the first angular position or from an intermediate angular position between the first and second angular positions, into the second angular position upon rotation of the input hub in the first direction from the second angular position into the third angular position; and/or the drive train is formed such that instead of the storage element, the drive train rotates or can rotate the output hub from the first angular position or from an intermediate angular position between the first and second angular positions, into the second angular position upon rotation of the input hub in the first direction from the second into the third angular position.

7. The energy accumulator according to claim 3, wherein the drive train is formed so as to prevent the output hub from being able to depart from the second angular position by more than a specified deviation angle upon rotation of the input hub in the first direction and between the second and third angular positions.

8. The energy accumulator according to claim 3, wherein the drive train comprises a locking mechanism coupled to the output hub and formed so as to prevent the output hub from being able to depart from the second angular position by more than the deviation angle and/or toward the first angular position upon rotation of the input hub in the first direction and between the second and third angular positions; prevent the output hub from being able to depart from the second angular position toward the first angular position when the output hub is in the second angular position; prevent the output hub from being able to depart from an intermediate angular position toward the first angular position when the output hub is in the intermediate position between the first and second angular position; prevent the output hub from remaining in the intermediate angular position upon rotation of the output hub from the second into the first angular position.

9. The energy accumulator according to claim 3, wherein the drive train comprises a release mechanism formed so as to release the locking mechanism upon rotation of the input hub in the first direction and in the second angular position or between the second and third angular positions.

10. The energy accumulator according to claim 3, wherein the drive train is formed so as to block the output hub upon rotation of the input hub in the first direction from the third angular position into a predetermined fourth angular position.

11. The energy accumulator according to claim 10, wherein the drive train is formed so as not to tension the storage element upon rotation of the input hub in the first direction from a predetermined fifth angular position before the first angular position, into the first angular position, while the output hub is stationary.

12. The energy accumulator according to claim 11, wherein the drive train comprises a cam disk having a cam and the input hub; a cam follower that follows the cam and that is formed such that each of the movements of the cam follower run synchronously oppositely to each other upon rotation of the input hub in the first direction from the fifth into the fourth angular position and upon rotation of the input hub in an opposite second direction from the fourth into the fifth angular position; and/or the cam is formed such that each of the movements of the cam follower run synchronously oppositely to each other upon rotation of the input hub in the first direction by a differential angle from the fifth into the fourth angular position and upon rotation of the input hub in the first direction by the same differential angle from the fourth angular position; and/or the cam is in itself closed; and/or the cam is formed such that the differential angle between the fourth and fifth angular positions is 180 or 90 or 60 or 45 or a whole-number fraction of 180.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the following, embodiments of the invention are exemplified and explained in detail by means of the attached drawings. The individual features thereof are, however, not limited to the individual embodiments but can be connected and/or combined with individual features described further above and/or with individual features of other embodiments. Each example in the illustrations is provided by way of explanation, not limitation of the invention. The figures show as follows:

(2) FIG. 1 a preferred embodiment of a on-load tap changer with an force-storage unit;

(3) FIG. 2 a first view of a preferred embodiment of the force-storage unit of FIG. 1 with a locking mechanism in a first embodiment;

(4) FIG. 3 a second view of the force-storage unit from FIG. 2;

(5) FIG. 4 a third view of the force-storage unit from FIG. 2;

(6) FIG. 5 a fourth view of the force-storage unit from FIG. 2;

(7) FIG. 6 a fifth view of the force-storage unit from FIG. 2;

(8) FIG. 7 a sectional view of an exemplary embodiment of a first coupling for the force-storage unit;

(9) FIG. 8 a sectional view of an exemplary embodiment of a second coupling for the force-storage unit;

(10) FIG. 9 a bottom view of an exemplary embodiment of a cam disk for the force-storage unit;

(11) FIG. 10 a second embodiment of the locking mechanism;

(12) FIG. 11 a third embodiment of the locking mechanism.

SPECIFIC DESCRIPTION OF THE INVENTION

(13) In FIG. 1, a preferred embodiment of a embodiment of a on-load tap changer is 10 schematically illustrated, which exemplarily comprises a motor 11 with an output shaft 12, a load diverter switch 13 with an input shaft 14, an force-storage unit 15, and a selector 16. The load diverter switch 13 and the selector 16 are formed in the know manner and are therefore not illustrated in further detail. The selector 16 comprises a plurality of fixed contacts (not illustrated) and two movable moving contacts (not illustrated), and it is coupled to the output shaft 12 for driving the moving contacts. The load diverter switch 13 comprises a movable switch contact unit (not illustrated), and it is coupled to the input shaft 14 for driving the switch contact unit. By way of the force-storage unit 15, the input shaft 14 is coupled to the output shaft 12 that the motor 11 drives at a constant rotational speed upon a switching process of the on-load tap changer 10.

(14) A preferred embodiment of the force-storage unit 15 is schematically illustrated in different views in FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 6. The force-storage unit 15 exemplarily comprises a transmission, an elastic storage element 17, a crank 18 that couples the storage element 17 to the transmission, and a frame (not illustrated in FIG. 3, 4, 5) with an upper and a lower frame plate 19, 19 and with struts that connect the frame plates 19 to each other. The storage element 17 is pivotably mounted with a fixed end (on the left in FIG. 2) to the frame plates 19, and it is rotatably mounted with an oppositely located, movable end (on the right in FIG. 2) to the crank 18.

(15) The transmission exemplarily comprises a cam disk 20 (not illustrated in FIG. 5) with an input hub 201 and with a groove-shaped cam 202 (FIG. 3) in its underside, a cam follower 21 (FIG. 3) following the cam 202, an input gear 22 with a rotation axis 221, an output gear 23 with an output hub 231 and a flywheel 232, a first and second coupling 24, 25 (FIG. 2, 5, 6), a locking mechanism 26 in a first embodiment with a first and a second pawl 261, 262 and with a first and a second latching nose 263, 264, an A gear 27, a B gear 28, a C gear 29, a D gear 30, and a release mechanism with a first and a second release bolt 31, 31.

(16) The input hub 201 is rotationally fixed to the output shaft 12 (not illustrated). The output hub 231 is rotationally fixed to the input shaft 14 (not illustrated). The input gear 22 supports the cam follower 21 radially offset from the rotation axis 221 and projects upward into the cam 202. Cam disk 20 and cam follower 21 together form a cam transmission that constitutes a variable transmission interposed between input hub 201 and storage element. The A gear 27 meshes with the input gear 22 The B gear 28 is coupled with the A gear 27 by way of the first coupling 24. The C gear 29 meshes with the B gear 28. The D gear 30 is coupled with the C gear 29 by way of the second coupling 25, and it meshes with the output gear 23. The crank 18 is rotationally fixed to the C gear 29. The input gear 22 is thus coupled by way of A gear 27, first coupling 24, B gear 28, C gear 29, and crank 18 to the storage element 17. The output gear 23 is thus coupled by way of D gear 30, second coupling 25, C gear 29, and crank 18 to the storage element 17.

(17) The output gear 23 is located below the lower frame plate 19, and the flywheel 232 is fastened to the underside of the toothing of the output gear 23. Each pawl 261, 262 is pivotably mounted radially outside of the toothing on the upper side of the flywheel 232 and has a pawl claw at its radially outer free end for seizing the assigned latching nose 263, 264 upon engagement, whereas its radially inner free end serves as stop for the assigned release bolt 31, 31 upon disengagement. The latching noses 263, 264 are fastened radially outside of the pawls 261, 262 to the underside of the lower frame plate 19 and each have a shallowly radially inwardly running contact surface and a sharply radially outwardly running latching surface that adjoins the radially inner end of the contact surface. The release bolt 31, 31 are fastened to the B gear 28 and project through an arc-shaped slot in the lower frame plate 19 downward to a level of the assigned pawl 261, 262. By a suitable rotation of the B gear 28, each release bolt 31, 31 can be advanced against the inner free end of the assigned pawl 261, 262 for disengagement, and its pawl claw can pivot radially inward away from each particular latching nose 263, 264 against the preload force of an assigned preload spring that supports itself on the flywheel 232.

(18) In FIG. 7 and FIG. 8, exemplary embodiments of the first or, as the case may be, of the second coupling 24, 25 are schematically illustrated in a cross section at a right angle to its appropriate rotational axis. The couplings 24, 25 are each formed freewheel-type and in the manner of a claw coupling, and they each have a predetermined first or, as the case may be, second angular backlash that allows a correspondingly limited freewheel in each direction of rotation.

(19) The first coupling 24 (FIG. 7) comprises a first coupling claw 24 with a first and second stop surface 241 (FIG. 5, 6), 242 and a second coupling claw 24 with a third and fourth stop surface 243, 244 (FIG. 5). The first coupling claw 24 is fastened to the underside of the A gear 27 and the second coupling claw 24 to the upper side of the B gear 28.

(20) The first coupling 24 operates in the following manner: When the A gear 27 is rotated clockwise out of the position shown in FIG. 5, then the first coupling claw 24 of FIG. 7 is also rotated clockwise. FIG. 7 shows an intermediate position where the stop surface 241 is not yet in contact with stop surface 243, and second coupling claw 24 and B gear 28 thus remain in their position. As soon as A gear 27 and coupling claw 24 have rotated so far that stop surface 241 is in contact with stop surface 243, the B gear 28 is driven along by way of coupling claw 24 upon further rotation, and it is also rotated clockwise out of the position shown in FIG. 5. When A gear 27 is then rotated counterclockwise, coupling claw 24 is rotated counterclockwise as well, with stop surface 242 initially not yet being in contact with stop surface 244 and second coupling claw 24 and B gear 28 thus remaining in their position. As soon as A gear 27 and coupling claw 24 have rotated so far, that is by the first angular backlash, that stop surface 242 is in contact with stop surface 244, the B gear 28 is driven along upon further rotation, and it is rotated counterclockwise as well. When driving the B gear 28, the manner of operating is correspondingly reversed.

(21) The second coupling 25 (FIG. 8) comprises a first coupling claw 25 with a first and second stop surface 251 (FIG. 2), 252 (FIG. 2, 5) and a second coupling claw 25 with a third and fourth stop surface 253, 254. The first coupling claw 25 is fastened to the C gear 29 and the second coupling claw 25 to the upper side of the D gear 30. The operating mode of the second coupling 25 corresponds to that of the first coupling 24.

(22) FIG. 9 is a bottom view of the cam disk 20 from FIG. 4 with an exemplary embodiment of the cam 202. Cam 202 is in itself closed and has a first section 202A with a constant first radius, a second section 202B with a constant second radius smaller than the first radius, a third section 202C connecting the sections 202A, 202B at their lower ends as seen in FIG. 9 and having a changing radius, and a fourth section 202D connecting the sections 202A, 202B at their upper ends as seen in FIG. 9 and having a changing radius; the radii in this context referring to the input hub 201. Cam 202 thus offers a variable transmission.

(23) The cam transmission forming the variable transmission operates in the following manner: The starting point, as an example, is the A basic position shown in FIGS. 3 to 6, where the cam disk 20 takes up the position shown in FIG. 9 that corresponds to a fifth angular position 5=0, cam follower 21 is positioned in section 202A (FIG. 3, 4), stop surface 242 is in contact with stop surface 244 and stop surface 241 is consequently spaced apart from stop surface 243 by the entire first angular backlash, stop surface 252 is in contact with stop surface 254 and stop surface 251 is consequently spaced apart from stop surface 253 by the entire second angular backlash, storage element 17 is relaxed, and pawl 261 is engaged with latching nose 263 and pawl 262 is disengaged. The end point will be a B basic position, where the cam disk 20 takes up a fourth angular position 4=180, cam follower 21 is positioned in section 202B, stop surface 241 is in contact with stop surface 243 and stop surface 242 is consequently spaced apart from stop surface 244 by the entire first angular backlash, stop surface 251 is in contact with stop surface 253 and stop surface 252 is consequently spaced apart from stop surface 254 by the entire second angular backlash, storage element 17 is relaxed, and pawl 262 is engaged with latching nose 264 and pawl 261 is disengaged.

(24) When the motor 11 rotates the cam disk 20 in a first direction R1 by way of output shaft 12 and input hub 201 from this A basic position and thus from the fifth angular position 5 into a first angular position 1, then the cam follower 21 first moves in section 202A toward section 202C and then continues as far as into section 202C. Since the radius of cam 202 is constant in section 202A, input gear 22 is not moved, and this corresponds to an infinite transmission of the cam transmission. The transmission thereby blocks the output gear 23 from performing an undesired rotation driven by the input shaft 14. In section 202C, the radius first rapidly decreases; this corresponds to a small transmission. Input gear 22 and A gear 27 are consequently rotated fast until the first angular backlash is exhausted in angular position 1 such that now stop surface 241 is in contact with stop surface 243 and stop surface 242 is thus now spaced apart from stop surface 244 by the entire first angular backlash. In this rotation from angular position 5 to angular position 1, B gear 28 and the succeeding gear train are consequently not driven so that storage element 17 is not tensioned and output hub 231 stands still.

(25) When the motor 11 rotates the cam disk 20 from angular position 1 further in direction R1 up to a second angular position 2, then the cam follower 21 continues to move in section 202C toward section 202B. Since the radius in section 202C, however, decreases slower now than before, this corresponds to a greater transmission. Input gear 22 and A gear 27 are consequently rotated slower. B gear 28, C gear 29, and crank 18 are now also rotated by way of the first coupling 24, and storage element 17 is thus tensioned until the storage element 17 is tensioned up to its top dead center in angular position 2 and the second angular backlash is exhausted such that now stop surface 251 is in contact with stop surface 253 and stop surface 252 is thus now spaced apart from stop surface 254 by the entire second angular backlash. In this rotation from angular position 1 to angular position 2, D gear 30 and the succeeding gear train are consequently not driven so that output hub 231 stands still. B gear 28 advances release bolt 31 up to the stop of the first pawl 261.

(26) When the motor 11 rotates the cam disk 20 from angular position 2 further in direction R1 up to a third angular position 3, then the cam follower 21 continues to move in section 202C up to section 202B. Release bolt 31 is consequently pressed against pawl 261 by B gear 28 and pawl 261 is disengaged from latching nose 263. At the same time, crank 18 presses storage element 17 beyond the top dead center so that storage element 17 relaxes, and output gear 23 meanwhile rotates from the first angular position 1 shown in FIGS. 2 to 6 into a second angular position 2. In angular position 1, the flywheel 232 with its end on the right as seen in FIG. 6 is in contact with a stop block in front as seen in FIG. 6, which stop block is fastened to the underside of the lower frame plate 19. In angular position 2, the flywheel 232 with its end on the left as seen in FIG. 6 is in contact with a stop block in the back as seen in FIG. 6, which stop block is fastened to the underside of the lower frame plate 19, pawl 262 is engaged with latching nose 264, and pawl 261 is disengaged.

(27) When the motor 11 rotates the cam disk 20 from angular position 3 further in direction R1 up to a fourth angular position 4 that corresponds to the B basic position, then the cam follower 21 moves into section 202B. Since the radius of cam 202 is constant in section 202B, input gear 22 is not moved, and this corresponds to an infinite transmission of the cam transmission. The transmission thereby blocks the output gear 23 from performing an undesired rotation driven by the input shaft 14.

(28) The cam 202 is exemplarily formed such that

(29) each of the particular movements of the input gear 22 run oppositely to each other, both upon the previously explained rotation of the input hub 201 in the first direction R1 from angular position 5 into angular position 4 and upon a further rotation of the input hub 201 in an opposite, second direction R2 from the angular position 4 back into the angular position 5; and

(30) each of the particular movements of the input gear 22 run oppositely to each other, both upon the previously explained rotation of the input hub 201 in direction R1 from angular position 5 into angular position 4 and upon a further rotation of the input hub 201 from the angular position 4 in direction R1 by the same differential angle that here exemplarily is 4-5=180.

(31) In the normal case, the storage element 17 relaxes so rapidly and with such a force that the C gear 29 rotates so fast that it rotates the B gear 28 faster than the input gear 22 rotates the A gear 27. The stop surface 241 consequently departs from the stop surface 243 so that coupling 24 runs freely again. In order to be able to attain a re-pressing of the output gear 23 by the motor 11 as promptly as possible in the instance that the storage element 17 cannot rotate the output gear 23 fast enough, the radius returns to decreasing quicker in section 202C; and this implies a smaller transmission and faster rotation of input gear 22 and output gear 23. In this case, the transmission, either together with the storage element 17 or even instead of the storage element 17, can consequently rotate the output gear 23 by means of the motor 11 from angular position 1 or from an intermediate angular position between angular position 1 and angular position 2, into the angular position 2.

(32) A second embodiment of the locking mechanism 26 is schematically illustrated in FIG. 10. As this embodiment is similar to the first embodiment, primarily the differences will be explained in more detail in the following passages. Latching nose 264 is formed in analogy to latching nose 263 and is not illustrated.

(33) In this embodiment, the first latching nose 263 has an intermediate latching surface 32 located on its contact surface between its latching surface and its opposite end, which intermediate surface is seized by the pawl 261 with its pawl claw when the output gear 23 upon rotation from angular position 1 into angular position 2 reaches a corresponding intermediate angular position between this angular positions 1,2. The locking mechanism 26 consequently prevents the output gear 23 from being able to depart from this intermediate angular position toward its first angular position 1.

(34) In this embodiment, the locking mechanism 26 comprises a first spring plate 265 assigned to the latching nose 263, a second spring plate (not illustrated) assigned to the latching nose 264, and two guide pins 266, 267 assigned to the pawls 261, 262. The first spring plate 265 is fastened with a fixed end (on the left in FIG. 10) radially within its latching nose 263 to the underside of the lower frame plate 19, and with its other, free end (on the right in FIG. 10), it presses radially outward against the connecting edge between contact surface and latching surface. The fixed end is located in the area of the intermediate latching surface 32. Each guide pin 266, 267 is fastened on the upper side of the pawl claw of its particularly assigned pawl 261, 262. When the pawl 261 engages, the guide pin 266 is guided from left to right in FIG. 10 in the intermediate space between spring plate 265 and latching nose 263 until the output gear 23 has reached its second angular position 2 shown in FIG. 10, where the pawl 261 is engaged and the guide pin 266 has departed from the intermediate space. Upon disengaging, the guide pin 266 is moved radially inward past the free end of the spring plate 265, and upon further rotation of the output gear 23 toward the first angular position 1, it slides from right to left in FIG. 10 along the side of the spring plate 265 that is turned away from the latching nose 263, and it prevents the pawl 261 from being able to seize the intermediate latching surface 32 with its pawl claw. The locking mechanism 26 consequently prevents the output gear 23 from being prone to remain or get caught or stuck in this intermediate angular position upon rotation of the output gear 23 from the angular position 2 into the angular position 1.

(35) A second embodiment of the locking mechanism 26 is schematically illustrated in FIG. 11. As this embodiment is similar to the second embodiment, primarily the differences will be explained in more detail in the following passages. Latching nose 264 is formed in analogy to latching nose 263 and is not illustrated.

(36) In this embodiment, the locking mechanism 26 comprises a first cover part 268 assigned to the latching nose 263 and a second cover part (not illustrated) assigned to the latching nose 264 instead of the spring plates 265, 266. In comparison to the second embodiment, the intermediate latching surface 32 is located closer to the latching surface and is not discernible, because it is concealed by the cover part 268. By means of a preload spring that supports itself at the radially outer surface of the latching nose 263, the cover part 268 is preloaded with its right end as seen in FIG. 11 radially outwardly against the connecting edge between contact surface and latching surface. With its other end on the left in FIG. 11, the cover part 268 is located spaced apart from the latching nose 263. When the pawl 261 engages, the guide pin 266 is guided from left to right in FIG. 11 in the intermediate space between cover part 268 and latching nose 263 until the output gear 23 has reached its second angular position 2 shown in FIG. 11, where the pawl 261 is engaged and the guide pin 266 has departed from the intermediate space. Upon disengaging, the guide pin 266 is moved radially inward past the free end of the cover part 268, and upon further rotation of the output gear 23 toward the first angular position 1, it slides from right to left in FIG. 11 along the side of the cover part 268 turned away from the latching nose 263, and it prevents the pawl 261 from being able to seize the intermediate latching surface 32 with its pawl claw. The locking mechanism 26 consequently prevents the output gear 23 from being prone to remain or get caught or stuck in this intermediate angular position upon rotation of the output gear 23 from the angular position 2 into the angular position 1.