An energy accumulator, frequently also referred to as a force-storage unit, serves in an on-load tap changer with an output shaft, an input shaft, and a load diverter switch for converting a continuous, slow rotation of the output shaft being driven by a motor at a constant rotational speed into an abrupt, rapid rotation of the input shaft driving the load diverter switch. Numerous force-storage units are already known that enable the abrupt rotation of the input shaft by means of a storage spring. The principle is always the same: the output shaft driven by the motor at a constant rotational speed loads the storage spring to a maximum point, and, after exceeding this maximum point, the storage spring suddenly unloads and thereby abruptly drives the input shaft.
DE 28 06 282 [GB 2,014,794], EP 0 355 814, DE 10 2005 027 524 [U.S. Pat. No. 7,518,075], DE 102005 027 527 [U.S. Pat. No. 7,652,218], DE 10 2010 020 130 [US 2014/0190803], and EP 2 760 034 [US 2015/0001053] each describe an on-load tap changer with an force-storage unit comprising a storage spring, a drive train, a frame for the drive train, an eccentric, a loading slide and a release slide. The drive train comprises an input hub and an output hub. Due to these slides, such force-storage units are also referred to as slide force-storage units.
The output shaft is rotationally fixed to the input hub in these known on-load tap changers. The input hub is rotationally fixed to the eccentric. The eccentric is fixedly connected to the loading slide. The storage spring supports itself between the loading slide and the release slide. The loading slide and the release slide can move relative to the frame along a linear guide independently from each other back and forth between two end positions. The release slide is fixedly connected to the output hub.
The eccentric together with the loading slide consequently form a tensioning element formed such that it engages at the storage element for tensioning and then tensions the storage element upon rotation of the input hub, and the release slide forms a relaxing element formed such that it engages at the storage element for driving the output hub and then drives the output hub upon relaxation of the storage element.
DE 102006 008 338 [U.S. Pat. No. 8,119,939] and DE 102009 034 627 [U.S. Pat. No. 8,748,758] each describe an on-load tap changer with an force-storage unit comprising a storage spring, a drive train, a frame for the drive train, a drive element in the form of a gear with two axially protruding stop surfaces and a crank with a crankpin. The drive train comprises an input hub and an output hub. Due to the crank, such force-storage units are also referred to as crank force-storage units.
The output shaft is rotationally fixed to the input hub in these known on-load tap changers. The input hub is rotationally fixed to the drive element. The drive element and the crank can rotate relative to each other back and forth between a first end position and a second end position. The stop surfaces correspond with the crank in such a manner that the first stop surface is in contact with the first side of the crank in the first end position, and the second stop surface is in contact with the second side of the crank in the second end position, with these sides being located opposite to each other. Consequently, the drive element is fixedly connected to the crank in these end positions. The storage spring is rotatably linked with its free end to the crankpin and pivotably supports itself with a fixed end on the frame. The free end can move relative to the fixed end along a linear guide back and forth between two end positions. The crank is coupled to the output hub.
The crank together with the drive element consequently form a tensioning element formed such that it engages at the storage element for tensioning and then tensions the storage element upon rotation of the input hub, and the crank forms a relaxing element formed such that it engages at the storage element for driving the output hub and then drives the output hub upon relaxation of the storage element.