US2724747A - Rotary switch having device for placing line wipers in operating position after selection rotation thereof - Google Patents

Description

Nov. 22, 1955 F, ULRICH ET AL 2,724,747

ROTARY SWITCH HAVING DEVICE FOR PLACING LINE wIPERs IN OPERATING POSITION APTER SELECTION ROTATION THEREOF Filed Oct. 9, 1952 INVENTORS FRITZ ULRICH,

WILLY LOHS HELMUT HOFMANN, KARL CENTMAIER a H NS EDER BY A W ATTORNEY United States Patent 1 2,724,747 ROTARY swrrcn HAVING DEVICE FOR PLACING LINE WIPERS IN OPERATING POSITION AFTER SELECTION ROTATION THEREOF Fritz Ulrich, Munich-Solln, and Willy Lohs, Helmut Hofmann, Karl Centmaier, and Hans Eder, Munich, Germany, assignors to Siemens & Halskc Aktiengesellschaft, Munich, Germany, a corporation of Germany Application October 9, 1952, Serial No. 313,854 Claims priority, application Germany October 12, 1951 9 Claims. (Cl. 179-2751) This invention relates to a rotary switch of the kind disclosed in copending application Ser. No. 269,224, filed January 31, 1952, and is particularly concerned with an improved device, for use in such a switch, for placing in operating position the line wipers which are held out of engagement with the bank contacts during the rotation thereof.

The copending application describes a switch provided with wipers which are for current-conducting purposes connected with slip rings. The line wipers are held out of engagement with the bank contacts during the rotation thereof, but are always in sliding engagement with the associated slip rings. The slip rings and the associated contact points of the line wiper springs carry silver coatings so as to provide for properly high-grade contacts whichare required for satisfactory speech transmission. The sliding action between the contact points or portions of the wiper springs and the slip rings causes wear of the valuable silver coatings and results in polishing the associated contacting surface. It has been found, however, and is generally known that polished contact surfaces do not furnish good contacts, causing resistance alterations at the corresponding contact points, even responsive to slight vibrations. Much more reliable than sliding contacts are pressure contacts as they have already been provided for the contact points of the line wipers at the bank multiple. side thereof in an embodiment of a rotary switch according to the above-noted copending application.

The object of the invention is to improve the contacts between the contact portions of the line wipers and the associated contactors or slip rings, which are disposed in the talking circuits of connections made, and to provide at'the same time more favorable conditions for the operation of the wiper-controlling magnet.

'Another object is to keep the weight of the rotatable parts of the switch as small as possible so as to avoid disturbing effects of inertia forces incident to starting and stopping the switch.

'The invention realizes the above noted objects by the provision of line wipers which are effective in the manner of pressure contacts at the bank contact side and also at the slip ring side. The wiper control magnet must in such structure overcome the opposing spring forces of the arms of the wipers at the slip ring side and also at the bank contact side. The wipers are for this purpose, in accordance with the invention, formed as members having two arms which are centrally secured to the armature of the magnet, and the latter is pivotally mounted so as to effect successive contacting of the contact portions of the wiper arms with their associated contact surfaces. This feature approximates the motions of the parts to the force-displacement of the control magnet. The attractive force of the magnet armature increases with the reduction of its stroke, and the armature can at the concluding part of its stroke overcome the opposing forces of the two resilient wiper arms.

In order to obtain secure journalling of the armature which rotates about a stationary magnet coil, the invention provides, in accordance with another feature, a shaft journal for the armature in place of the previously used link-spring-journal. The shaft of this journal is held by a structural part of the switch drive mechanism and is disposed in the space between the slip rings and the bank confacts in such a manner that the contact portions of the wiper arms move in directions nearly radial to the slip rings and the bank contacts. The structural part which carries the armature shaft is made in the form of an angular bracket which is fastened to the wiper carrier of the drive mechanism and serves at the same time as a mounting for the control wipers, while the line wipers are fastened to the armature of the control magnet.

The individual contact springs forming the control wipers and the line wipers, respectively, are fastened on their carriers or mounting means by screws and insulating guide pins so as to make them easily exchangeable. Hard rubber rivets are used to form, after swelling, heads acting as guide pins which unite the associated cover plates, the intermediate insulating members and the spring-supporting strips with the corresponding carrier. As will be shown later, the contact springs may, by the use of these guide pins, be held in their positions by single screws.

An embodiment of the invention will now be described with reference to the accompanying diagrammatic drawings, in which Fig. 1 is a simplified perspective view of a portion of the drive mechanism of a switch, showing the manner of pivotally mounting the armature of the control magnet and the manner of fastening the wipers; and

Fig. 2 shows a sectional view taken along the line ab of Fig. 1.

General details of the switch structure may be had from the copending application mentioned before.

Referring now to the drawings, numeral 1 indicates the stationary switch shaft which also forms the core for the coil 2 of the control magnet. Numeral 3 indicates a toothed drive Wheel which is driven by a stepping motor (not shown) to rotate about the axis 1, and rigidly connected with the dgive wheel 3 is the wiper carrier 4. Secured to the wiper carrier is an angular bracket 5 having ears formed at the free end of one of its legs for holding the shaft 6 on which ispivoted the magnet armature 7 by the angular bracketlike extensions 8 projecting therefrom. The armature 7 is held in lifted or released position by a leaf spring 9 which engages a slot in the bracket 5 and serves as the armature-restoring spring. Upon the stationary magnet coil 2 are disposed the annular contactors or slip rings 10, as described in the previously mentioned copending application.

Assuming a four-wiper rotary switch, there will be provided upon the coil body 2 four slip rings--two for the current supply to the control wipers, and two for the line wipers. For the sake of convenience, there are shown in Fig. 1 only two wipersone control wiper 11 and one line wiper 12. The second line wiper 12 is indicated fractionally.

The armature 7 is at its opposite ends provided .with pole arms for engagement with the correspondingly disposed disklike pole shoes 13 of the magnet, thus leaving space between these pole arms for the contacting ends of the arms of the wipers such as 11 and 12 for engagement with the associated contactors or slip rings 10. The control wipers, one of which is shown at 11 are secured on the bracket 5 in insulated relation thereto, and the line wipers such as 12, 12 are secured to the armature 7.

As is apparent from the drawings, the wipers have two arms, the central portions of these arms being secured to their respective carriers, i. e., to the bracket 5 and to the armature 7. One of the arms of each wiper. establishes 15 which are wound on insulating carriers such as 14. Two bank contacts are shown in Fig. 1, one for engagement by the corresponding contact portion of the control wiper 11 and one line bank contact 15 for engagement by the contact portion of the line wiper 12. The insulating carriers such as 14 are disposed in the switch housing radially with respect to the switch axis as explained more in detail in the previously mentioned copending application. In other words, the bank contacts are not disposed in piles forming a bank but on insulating carriers such as 14. The wipers such as shown in the drawings therefore engage the bank contacts edgewise at the extreme inner ends thereof where the contacts which are wound on the insulating strip 14-engage the inner edge of the strip. The control wipers such as wiper 11 are mounted on the bracket 5 extending from the carrier 4 which rotates with the wheel 3 and the right hand end thereof will therefore always establish edgewise engagement with the corresponding bank contacts while the left hand end will glide along the associated slip ring 10. The line wipers such as 12, 12 will likewise rotate with the carrier 4, being mounted on the armature 7 which in turn is pivoted on the shaft 6 carried by the bracket 5 secured to the rotating carrier 4, but the right hand end of these line wipers will be normally held out of engagement with the corresponding bank contacts and the left hand end will be similarly held out of engagement with the associated slip ring due to the action of the spring 9 which holds the armature normally in released position.

The stroke of the armature '7 is limited by the stop 16 (Fig. 2) which is connected in the pile including the control wiper spring 11 and is fastened therewith on the bracket 5 by means of the hard rubber rivets 17. The metallic cover plate 18, the intermediate insulator 19, the bracket 5, the stop 16 for the armature 7, the insulator 20 and the spring-support strip 21 are connected together by means of the hard rubber rivets 17. The rivet heads form, upon swelling, on one side of the assembly guide pins for the wiper spring 11 which is slipped thereon together with the second spring-support strip 26 and the counterplate 22. The assembly is held together by the screw 25. The bore. in the bracket 5 permits passage of the screw 25 out of contact with the shank thereof. The counterplate 22, which is guided by the rivet heads, will be tightened responsive to tightening of the screw 25, thus securing the control wiper spring 11 in position. Exchange of the wiper spring therefore requires merely removal of the single screw 25.

The line wipers l2, 12' are secured on the armature 7 in similar manner by a single screw 28. Hard rubber rivets 17 are likewise used to form guide pins for the wiper springs 12 and associated spring-support strip 27, cover plate 23 and the insulator 24.

The pivot of the armature, which is fixed by the bracket 5, is disposed in the space between the slip rings and the bank contacts. Accordingly, the contact portions of the line wipers 12 which are disposed at the opposite ends thereof will, upon attraction of the armature, engage the associated selected bank contacts and the coacting slip rings, respectively, in pressure contact therewith.

We claim:

1. in a rotary switch having a stationary shaft and stationary bank contacts disposed along an are about said shaft and radially spaced therefrom and having a stationary annular contactor surrounding said shaft and a wiper set comprising a wiper having a first contact-making arm for engagement with said contractor and a second contactmaking arm for selective contact engagement with said bank contacts, a device for mounting and for operating said wiper, said device comprising a carrier, drive. means for rotating said carrier about said stationary shaft, an armature pivoted on said carrier and rotatable. therewith, means for mounting said wiper on said armature for rotation therewith and with said carrier to position said second contact-making arm in alignment with a selected bank contact, a pole piece mounted on said shaft for magnetic coaction with said armature, and means for biasing said armature to maintain it normally during the rotation thereof in a normal angular position with said first and said sec nd contact-making arms of said wiper out of engagement with said contactor and said bank contacts, respectively.

2. The structure and cooperation of parts as defined in claim 1, comprising a magnet coil disposed about said shaft, said shaft forming a core for said coil, means for .ing said coil responsive to positioning said second contact-making arm of said wiper in alignment with a selected bank contact to cause said pole piece to attract said armature so as to move the arms of said wiper into pressure contact engagement with said contactor and with said selected bank contacts, respectively.

i. he structure and cooperation of parts as defined said armature at a point disposed between said statmnary shaft and said bank contacts.

4. in a rotary switch, a stationary shaft, a carrier disposed for rotation about the axis of said shaft and means for rotating such carrier, stationary bank contacts comprising controi contacts and line contacts disposed along an are about said shaft and radially spaced therefrom, stationary slip rings, a line wiper having at the opposite ends contact-making portions for engagement with one of said slip rings and with a selected line contact, respec- 22y, a control wiper having at the opposite ends contact-making portions for engagement with another one of said slip rings and with control contacts, respectively, means for mounting said control wiper on said carrier for rotation therewith with its respective contact-making portions in engagement with the respectively associated slip ring and with control contacts encountered during said rotation thereof with said carrier, means for pivotally mounting said line wiper on said carrier for rotation therewith with its respective contact-making portions out of engagement with the respectively associated slip ring and out of engagement with line contacts encountered thereby during the rotation thereof with said carrier, and means for moving said line wiper to move the contactmaking portions thereof into contact pressure engagement with the respectively associated slip ring and with a line contact, respectively.

5. T he structure and cooperation of parts as set forth in claim 4, wherein said last-named means for moving. said line wiper comprises a member pivotally mounted on said carrier and constituting an armature, and magnet means for magnetically affecting said armature to move it and therewith to move said line wiper as specified.

6. The structure and cooperation of parts as set forth in claim 5, wherein said magnet means is mounted on said stationary shaft.

'7. The structure and cooperation of parts as set forth in claim 5, wherein said magnet means is mounted on said stationary shaft, said magnet means comprising a coil carried by said shaft, and a pole piece carried by said coil, said shaft acting as a core for said coil.

8. The structure and cooperation of parts as set forth in claim 5, wherein said magnet means is mounted on said stationary shaft, said magnet means comprising a coil carried by said shaft, and a pole piece carried by said coil, said shaft acting as a core for said coil, said slip rings being mounted on the outside of said coil.

9. The structure and cooperation of parts as defined in claim 1, portion, stationary slip ring for sliding engagement by 0 said contact portion, and means for mounting said control wiper on said carrier for rotation therewith.

References Cited in the file of this patent UNITED STATES PATENTS 2,194,051 Muller Mar. 19, 1940 comprising a control wiper having a contact

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