US2307373A - Rotary electric switch - Google Patents

Description

1943. R. B. HUNTER ETAL 0 ROTARY ELECTRIC SWITCH Filed Aug. 9, 1941 s wwwfismm Patented Jan. 5, 1943 ROTARY ELECTRIC swrron Richard Hunter, Shorewood, and Harold L.

Mekelburg,

Milwaukee, Wis.,

assignors to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application August 9, 1941, Serial .No. 406,132

' l-Claims. (Cl. 74-565) This invention relates to rotary electric switches such as drum controllers of the reversible type.

Such controllers usually comprise a series of stationary contacts which cooperate with movable contacts, the latter being mounted on, and suitably insulated from a rotating shaft. The rotating shaft, with its contacts, generally called the drum, has considerable inertia. The drum is biased to an off position, and is provided with one or more operative positions on each side of,

the off position for connection of amotor, or other translating devices controlled thereby, for operation thereof in a forward or reverse direction, selectively,

The shaft may be operated in various conven-:; tional ways.

It may, for instance, be provided with an operating handle for direct manual control; In this case the drum may be biased to the off position by a centering spring, or it may be provided with a star-wheel with notches or indentations cooperating with a suitable pawl to retain it in any one of the various operating positions or in the off position, respectively.

In other cases, the operating shaft is provided with a, sheave wheel, over which a rope is wound by means of which the wheel is rotated alternately by pulling one or the other end of the rope. Such rope operated devices are usually provided with a centering spring, which biases the drum to the off-position and returns it to the latter position from an operating position upon release of the rope.

An object of the invention is to provide means for preventing too rapid movement of devices of the aforementioned character from an operative position on one side of a neutral or off position, to an operative position on the other side of the off position.

exceeds a predetermined normal rate.

Another object of the invention is to provide an anti-plugging device for a reversing switch or controller for a reversible electric motor.

Other objects and advantages will hereinafter appear.

The accompanying drawing illustrates one embodiment of the invention,

In the drawing,

Figure 1 is a fragmentary view (partly in section) of a reversing drum controller having our improved anti-plugging device applied thereto,-- the latter being shown in bottom plan.

Fig. 2 is a fragmentary cross sectional view, on the line 2-2 of Fig. 1,the stationary and movable contacts of the drum being shown more or less diagrammatically.

Referring to the drawing, the same shows an operating shaft l on-which is mounted a series of movable contacts diagrammatically indicated by 2, which cooperate with stationary contacts 3 (see Fig; 2) The shaft 1 is rotatably supported in a'bearing 4 of a top plate 5 of the drum controller, and is provided-with a cam B which is fastened to the shaft to rotate therewith. The cam 6 has cam surfaces 1 and 8 which intersect each other at 9. The cam 6 is also provided with a rectangular notch or recess ID,

The cam surfaces 1 and 8 are arranged to cooperate with cam surfaces II and I2 of an inertia device generally designated as is. The inertia device has an extension M which is adapted to enter the recess ID of the cam 6. The inertia device I 3 is rotatably supported on a pivot l5, which is mounted-on the top plate 5.

The mass of the inertia device I3 is preferably so disposed that it is substantially balance about the pivot IS in all angular positions. A tension spring [6 is interposed between the inertia device 13 and a fixed point on the top plate 5, so as to bias the former, tending to rotate it in a counterclockwise direction. The extent of such rotation is limited by an adjustable stop I I carried by the top plate 5.

A helical spring [8 surrounds the shaft l. The two straight ends of the spring l8 extend substantially radially and engage a pin l9 attached to the cam 6 and a pin 20 attached to the top plate 5,,insuch a manner that if the shaft is rotated in one or the other direction, the pin l9 tends to rotate one or the other end of the spring l8 to wind it tighter and to increase its tension, the pin 20 under these conditions acting to hold the other end of the spring against rotation, as

will be obvious. As a result, the spring l8 always tends to return the shaft 1, with its cam 6, to the off position,'which is the position of the cam shown in the drawing in full lines. A handle 2! is provided to rotate the shaft I.

The device operates in the following manner: With the drum in one of its on positions,

when either of the cam surfaces 1 or 8 engages the cam surfaces ll or l2, respectively, it tends to rotate the inertia device IS in a clockwise direction against the bias of the spring it, until the device is in the position shown in full lines in Fig. 1. In this position the cam 6 and with it the shaft i may be rotated in either direction by means of the handle 2i. Such rotation frees the inertia device It, and permits it to rotate counterclockwise to the dotted line position. After being rotated from the neutral position in either direction, the shaft i may now be further rotated as far as is desired, without interference between cam 6 and the inertia device l3. If, however, the shaft 5 and with it the cam 6 are returned at a high or abnormal rate of speed from an operative position, such as either one of the operative positions of cam 5 shown in dotted lines in Fig. 1, to the neutral position, the impact between the cam surfaces 7 and II or surfaces 8 and I2, respectively, causes the inertia device to be rotated clockwise, tending to carry it beyond the full line position shown in Fig. 1 until the extension l4 enters the recess Ill when the latter is opposite to the former, and thereby prevents further rotation of the cam 6, until the kinetic energy stored up in the inertia device'lt has been dissipated, whereupon the biasing spring 18 tends to rotate it counterclockwise, the cooperating cam surfaces, on cam 6 and inertia device l3, then serving to hold the latter in the full line position thereof illustrated. With the parts so positioned, the cam t and drum shaft I may be rotated from the intermediate or neutral position in either direction at any desired speed.

When no rotative force is applied'to handl 2| at the time of engagement of inertia device IS with recess it, the action of spring It serves to release pressure upon the extension M of inertia device 53, thereby facilitating counterclockwise rotation of device !3 by spring l6; whereas if rotative force is continuously applied to handle 2| the aforementioned result may be attained by a reduction of the rotative force, which enables spring It to overcome the friction of engagement of extension M of said inertia device with a wall of recess Ill.

The positions of the cam surfaces and recess of the cam 6 relatively to the cam surfaces and extension of the inertia device l3 may readily be adjusted by adjustment of the stop IT, to provide for wear and variations in alinement.

The use of the present invention is particularly advantageous in connection with rope operated reversing switches and the like which are biased to an off position by a powerful spring. In the past such devices had to be provided with friction brakes or the like (due to weight of the movable parts and the consequently necessary force of the spring) to retard their movement through the off position in the event of manual release of the rope in one of the running positions. a The present invention, however, automatically prevents plugging without requiring retarding means of the type which depend upon the uncertain effects of friction and which experience shows is greatly variable and uncertain.

We claim:

1. In a reversing controller, an operating shaft having an off position and rotatable to a running position on either side of said off position, a member attached to said shaft to rotate therewith and providedwith an abutment and a single recess, an inertia device rotatably supported on. a stationary pivot and provided with a dog adapted to engage said recess to locks said shaft against rotation in its 0 position under certain conditions, and alternatively to automatically engage said abutment when said shaft is rotating within a given angular range adjacent to both sides of said 0 position, and a spring biasing said inertia device to normally hold said dog out of engagement with said recess, said abutment and said inertia device being further arranged to cause said inertia device to rotate and carry said dog into engagement with said recess upon return of said shaft from either operative position to the o position above a given speed.

2. In a reversing controller, a contact mechanism having an operating shaft oscillatable from an off position to a running position on either side of said on position, a cam attached to said shaft and having an abutment and a recess, an inertia device oscillatable about a stationary pivot and adapted in one position toengage said recess when said shaft is in its off position to lock the same against rotation, a spring normally biasing said inertia deviceoutof engagement with said recess, means for limitingthe degree of movement of said inertia device under said bias, and an abutment on said inertia device adapted to engage said first named abutment when said shaft is within a given angular position on either side of said off position to move said inertia device against the bias ofsaid spring and to temporarily engage said recess under the influence of an impact between said abutment-s.

3. In a reversing drum controller, a contact mechanism having an operating shaft oscillatable from an off position to afrunningposition on either side of said off position, a cam attached to said shaft and having an abutment and a recess, an inertia device oscillatable about a stationary pivot and adapted in .one position to engage said recess when said shaft is in its ofi position to lock the same against rotation, a spring normally biasing said inertia device out of engagement with said recess, adjustable means for limiting the degree of movement of said inertia device under the bias of said spring, and an abutment on said inertia device adapted to engage said first named abutment when said shaft is within a given angular position on either side of said off position to move said inertia device against the bias of said spring'and to temporarily engage said recess under the influence of an impact between said abutments.

In a reversing drum controller, in combination, an operating shaft having an intermediate off position and rotatable to an on position on each side of said off position, associated means including a cam member positively rotatable with said shaft and an inertia member having a point of pivotal support fixed relatively to said cam member; and said cam and inertia members having cooperating parts, said cooperating parts comprising a pair of cam surfaces on said inertia member and a pair of cooperating cam surfaces and a single recess on said cam member and a single dog on said inertia member and cooperating with said recess to positively prevent movement of said shaft from either on position beyond said intermediate off position, in the event that the speed of such movement exceeds a predetermined normal rate.

5. In a reversing drum controller, an operating shaft having an off position and rotatable to a running position on either side of saidoif position, a member attached to said shaft to rotate therewith and provided with an abutment in the form of a double-inclined cam and a single recess, an inertia device rotatably supported by a stationary pivot, said inertia device having a portion in the form of a, double-inclined cam for cooperation with said first mentioned cam, a spring associated with said inertia device to normally bias the cam of the latter into engagement with said first mentioned cam, and said inertia device having another portion in the form of a lug engageable with one wall or another of said recess under given conditions, the arrangement being such that said shaft may be rotated from oif position to either running position at any speed and from either running position to the other at or below a predetermined speed without interference by said inertia member, the latter acting to lock said shaft in ofi position when the movement thereof from a running position is at a rate above said predetermined speed.

6. In a reversing drum controller, an operating shaft having an off position and rotatable to a running position on either side of said off position, a member attached to said shaft to rotate therewith and provided with an abutment in the form of a double-inclined cam, an inertia device rotatably supported by a stationary pivot, said inertia device having a portion in the form of a double-inclined cam for cooperation with said first mentioned cam, a spring associated with said inertia device to normally bias the cam of the latter into engagement with said first mentioned cam, and means arranged on said member and on another portion of said inertia device and adapted to permit rotation of said shaft from off position to either running position at any speed and from either running position to the other at or below a predetermined speed without interference by said inertia member, the latter acting to temporarily lock said shaft in the off position when the movement thereof from a running position is at a rate above said predetermined speed, said means comprising a single recess and a lug engageable with one wall or another of said recess under given conditions.

7. In a reversing drum controller, an operating shaft having an 01? position and rotatable to a running position on either side of said off position, a member attached to said shaft to rotate therewith and provided with an abutment in the form of a double-inclined cam, an inertia device rotatably supported by a stationary pivot, said inertia device having a portion in the form of a double-inclined cam for cooperation with said first mentioned cam, a spring associated with said inertia device to normally bias the cam of the latter into engagement with said first mentioned cam, and a lock arranged on said member and on another portion of said inertia device and comprising a single recess and a lug engageable with one wall or another of said recess under given conditions and adapted to permit rotation of said shaft from off position to either running position at any speed and from either running position to the other at or below a predetermined speed without interference by said inertia member, the latter acting to temporarily lock said shaft in the off position when the movement thereof from a running position is at a rate above said predetermined speed.

RICHARD B. HUNTER. HAROLD L. MEKELBURG.

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