Patent ID: 12230440

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion of the embodiments of the disclosure directed to a magnetic actuator assembly that includes at least two coupled and axially aligned magnetic actuators is merely exemplary in nature, and is in no way intended to limit the disclosure or its applications or uses. For example, the discussion herein refers to the actuator assembly being applicable for switching a vacuum interrupter, for example, in a single-phase self-powered magnetically actuated fault recloser for use in medium voltage power distribution networks. However, as will be appreciated by those skilled in the art, the actuator assembly will have other applications.

FIG.1is an isometric view of a magnetically actuated switch assembly10including a vacuum interrupter12coupled to a magnetic actuator assembly14that electrically opens and closes the vacuum interrupter12by actuating a drive rod16. The switch assembly10has particular application for use in a single-phase self-powered magnetically actuated fault recloser for use in medium voltage power distribution networks.FIG.2is a cross-sectional view of the actuator assembly14in an open position andFIG.3is a cross-sectional view of the actuator assembly14in a closed position. As will be discussed in detail below, the actuator assembly14includes two magnetic actuators18and20coupled together and axially aligned in series to provide an increased latching force without having to increase the diameter of the assembly14. It is noted that although the discussion herein refers to two stacked actuators, the same principles apply to stacking more than two actuators.

The actuator18includes an annular top plate24, an annular stator26and an annular spacer member28, where a coil32is wound on the stator26and where the plate24and the stator26define a central opening30. The actuator18also includes a slidable plunger38slidably positioned within the opening30. The plunger38includes a central channel40in which is positioned a tolerance spring42wrapped around a sleeve44, where the sleeve44is slidable in the channel40. The sleeve44includes a front flange46positioned adjacent to a front portion48of the plunger38that extends out of a back portion50of the plunger38, where the spring42is positioned between the back portion50and the flange46. The rod16extends through a central hole52in the top plate24into the opening30and through the sleeve44. The actuator18further includes four semi-annular permanent magnets54spaced apart and positioned between the plate24and the stator26.

The actuator20includes an annular top plate60, an annular stator62and an annular bottom plate64, where a coil66is wound on the stator62, an open area70is provided between the stator62and the bottom plate64, and the plate60and the stator62define a central opening68. The back portion50of the plunger38extends through a central hole72in the top plate60and into the opening68when the assembly14is in the open position. The actuator20also includes a slidable plunger76slidably positioned within the opening68and the open area70. The plunger76includes a central channel74in which is positioned a compliance spring78wrapped around a sleeve80. The sleeve80includes a front flange82positioned adjacent to a front portion84of the plunger76, where the spring78is positioned between a back portion86of the plunger76and the flange82. The sleeve80is slidable in the channel74, the plunger76is rigidly secured to the sleeve44, and the rod16is threaded into the sleeve80. The actuator20further includes four semi-annular permanent magnets92spaced apart and positioned between the plate60and the stator62and an opening spring94positioned between the stator62and a bottom flange96of the plunger76, where the flange96surrounds a central hole98in the bottom plate64.

Four bolts100extend the length of the actuator assembly14and extend through holes in the top plate24, the stator26, the spacer member28, the top plate60, the stator62, sleeves102that cross the open area70and the bottom plate64. Several nuts104are threaded onto the bolts100at strategic locations to hold the assembly14together.

As will be discussed below, when the actuator assembly14is in the closed position as shown inFIG.3, the latching force between the plunger76and the plate60and the latching force between the plunger38and the plate24increases the overall latching force of the actuator assembly14beyond a single magnetic actuator without increasing the diameter of the actuator assembly14over that of the single actuator. In order to operate effectively without the tolerance spring42, the plunger76would need to contact the plate60at the same time that the plunger38contacts the plate24when the actuator assembly14is moved to the closed position. In other words, in order for the actuator assembly14to achieve a maximum holding force, both of the plungers38and76must fully seat on their respective latching plates24and60. However, it is difficult to fabricate the parts in the actuator assembly14with the tolerances required to do that.

When the actuator assembly14is in the open position as shown inFIG.2, the sleeve80is positioned against the front portion84of the plunger76under the bias of the compliance spring78and the sleeve44is positioned against the front portion48of the plunger38under the bias of the tolerance spring42. When the actuator assembly14is commanded to close the vacuum interrupter12, current is simultaneously applied to the coils32and66which creates magnetic flux in the stators26and62, respectively, which draws the plunger76towards the plate60and the plunger38towards the plate24against the bias of the opening spring94, which is compressed between the stator62and the flange96. When the plunger76contacts the plate60, the latching force provided by the magnetic flux holds the rod16in the closed position. Additionally, the length of the sleeve44is set so that when the plunger76is latched to the plate60and the plunger38is latched to the plate24a gap106in the channel40is created between the flange46and the front portion48of the plunger38, which causes the spring42to compress between the back portion50of the plunger38and the flange46, which provides additional latching force of the plunger76against the plate60as a result of the spring42pushing against the flange46. The latching of the plunger76to the plate60also causes the spring78to compress between the flange82and the back portion86of the plunger76, which creates a gap108in the channel74between the flange82and the front portion84of the plunger76.

Once the interrupter12is closed the current to the coils32and66is turned off and the magnets54and92hold the plungers38and76in the latched position with the open spring94, the compliance spring78and the tolerance spring42under compression. When the vacuum interrupter12is opened, current is provided to the coils32and66in the opposite direction, which breaks the magnetic hold on the plungers38and66and the opening spring94pushes the plunger76away from the plate60and the sleeve44pushes the plunger38away from the plate24. The compliance spring78provides an additional initial opening force against the back portion86of the plunger76to help break the weld of the contacts in the vacuum interrupter12.

The foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the disclosure as defined in the following claims.