US2713095A - Adjustable mechanism for operating electric switches - Google Patents

Description

July 12, 1955 H. P. FULLERTON ADJUSTABLE MECHANISM FOR OPERATING ELECTRIC SWITCHES 5 Sheets-Sheet 1 Filed May 9, 1952 m t r wk d mt mm m e a H.

His AUb oTneg July 12, 1955 H. P. FULLERTON ADJUSTABLE MECHANISM FOR OPERATING ELECTRIC SWITCHES 5 Sheets-Sheet 2 Filed May 9, 1952 lnv enter Herbert P. Fullerton b8 W KM Q a hv l'lis Attorney.

July 12, 1955 H. P. FULLERTON 2,713,095

ADJUSTABLE MECHANISM FOR OPERATING ELECTRIC SWITCHES Filed May 9, 1952 5 Sheets-Sheet 5 f M w 9,2 5 CZ i3 211 1.1. l9

IE1: a2 97 w x /0/ -/6'6 a4 4 LP in ifimm i m I as Mir 4?; -//9 \E] 2% a; /20 m; w; lib my W E Inventor: @Q Herbert P. Fullerton 5 w w 3 y WWW bv ih 2Q, HIS Attorney.

United States Patent 0 ADEU TABLE MECHANISM FUR U-PERATING ELECTR1 SWITCHES Herbert P. Fullerton, ipringfield, Pa., assignor to General Electric Company, a corporation of New York Application May 9, 1952, Serial No. 286307 '7 Qlaims. ((Il. 20031) This invention relates to cyclic mechanism for operating electric switches and provides an improved adjustable cyclic mechanism capable of efiecting changes in the dwell or closed time of a sequentially operable switch contacts used in rectifiers or inverters of the mechanically controlled contact type as distinguished from converters utilizing electric valves.

In rectifiers of the mechanical type, it is well known that any contact cycle adjusting mechanism must be capable of the accurate timing of almost infinitesimal continuously successive intervals since the cyclically operated contacts open and close sixty times a second at the ordinary alternating current frequency or more than five million times each day and that the time during which the contacts of the rectifier are allowed to remain closed during each cycle comprising an opening and closing operation of the contacts is dependent in part upon the magnitude of current which is being supplied by the rectifier. Thus, if a mechanical rectifier is operating normally and delivering a certain amount of load current, an increase in the load current may require an increase in the dwell or closed time of the contacts of the rectifier with a corresponding decrease in the switch opening time during the cycle. Additionally, it is essential that the dwell or closed time of the contacts be substantially the same for all contacts. Since manufacture of parts to the required degree of accuracy is not practical and differences of wear during operation would, in any case, destroy such initial accuracy, it is found necessary to provide a method for adjusting individually the dwell time of the contacts. Further, when starting rectification, it is advantageous to utilize the contacts of the rectifier to energize the direct current buses before the final load circuit completing operation. Thus, the contact dwell of all contacts of the rectifier would be adjusted to zero, all other portions of the bus circuit would be closed, and then the contact dwell would be increased to that required for normal operation so that rectification could be started upon closure of the load circuit breaker.

In certain known mechanical rectifiers, it is necessary to shut down the rectifier in order to adjust the dwell time of the individual contacts to accommodate changes due to wear or replacement of contacts.

One object of this invention is to provide improved adjustable cyclic cam mechanism having a cam follower assembly including an oscillating element provided with an adjustable fulcrum for regulating the dwell time of the contacts of a mechanical rectifier so as to be capable of a desired adjustment while the rectifier is in operation.

Another object of this invention is to provide an improved mechanical rectifier which is characterized by a high degree of adaptability so as to accommodate a wide variety of service conditions.

According to the invention a revolving cam member is spaced from a rectilinearly movable switch member that is biased to a predetermined closed position and cooperates with adjustable thrust means including a reciprocating contact operating member biased out of engagement with the contact member and an oscillatory member interposed between the cam member and the reciprocating member and having the fulcrum of the oscillatory member adjustable to thereby inversely vary the contact opening and closing parts of each revolution of the cam member. The adjustable oscillatory member may comprise a tapered member disposed transversely with respect to the direction of operation of the reciprocatory member, and means for adjusting the fulcrum of the transversely disposed member is provided for shifting the reciprocating range of the contact operating member relative to the closed position of the switch member. In this way the dwell time of the switch member is regulated for each cycle comprising an opening and closing operation of the switch member.

For a better understanding of the invention reference may be had to the following description taken in conjunction with the accompanying drawings in which Fig. 1 is a schematic representation of a system showing the connections of a schematically represented mechanical rectifier; Fig. 2 is a perspective external view of a mechanical rectifier embodying the principles of the invention; Fig. 3 is a cross-sectional view through the apparatus of Fig. 2 showing one pair of contact members together with the adjustable thrust transmitting means comprising a principal feature of the invention; Fig. 4 is a front view partially in section of a mechanical rectifier embodying an alternative arrangement to that disclosed in Figs. 1, 2, and 3; Fig. 5 is a side view, also partially in section, of the arrangement shown in Fig. 4, and Fig. 6 is a view along the line 6-6 of Fig. 5.

In Fig. 1 a polyphase alternating current circuit comprising conductors 1, 2, and 3 supplies energy which is converted to direct current energy by the rectifier cyclically operable contact mechanism and supplied to the direct current conductors 4 and S. The alternating current circuit comprising conductors 1, 2, and 3 is connected to the primary 6 of a transformer having a secondary winding 7. The three phase windings of secondary winding 7 are respectively connected to the saturable reactors 8, 9, and it). These saturable reactors are constructed with a main and one or more control windings wound on a metallic core Thus, the reactors 8, 9 and 10 change their impedance as a function of control excitation together with the magnitude and polarity of the transformer secondary potential so that following commutation of current from the outgoing to the incoming contact the current in the outgoing contact is reduced to substantially zero and held there for a relatively long time during which the outgoing contact may be successfully opened. The function of reactors such as 8, 9, and N as a part of a converter system is more fully described in application Serial Number 172,134, filed July 5, 1950, by August Schmidt, Charles H. Titus, and Clodius H. Willis and assigned to the assignee of this invention. The reactors 8, 9, and 10 are controlled by the control windings 11, 12, and 13 which are energized from a source of electric energy having a controlled Wave shape and polarity. The adjustable resistor 14 is used to effect variations in the magnitude of current flowing through the control windings 11, 12, and 13. A reactor 15 may be connected in series with the windings 11, 12 and 13 so as to smooth the fiow of current through these control windings. Each of the reactors is provided with a main winding and such windings are designated by the numerals 16, 17, and 18.

Winding 16 is connected to fixed contacts 19 and 20, winding 17 is connected to the fixed contacts 21 and 22, and winding 18 is connected to fixed contacts 23 and 24. Negative direct current conductor 4 is connected to fixed contacts 25, 26, and 2". while positive direct current conductor 5 is connected with fixed contacts 28, 29 and 30. As is indicated in Fig. 1, the space between the abovementioned fixed contacts may be bridged by the bridging contacts 3136 each of which is respectively provided with its own biasing spring 3742 so as to bias the movable bridging contact to a predetermined closed position in engagement with the fixed contacts. Each pair of contact sets such as 19, 25, 31 and 2t), 28, 32 is controlled as indicated in Fig. l by its own cyclic contact operating mechanism generally designated by the numerals 43, 44, and 45. Since these contact operating mechanisms are identical, the following description will be by reference to the operating mechanism 43.

Contact operating mechanism 43 utilizes a revolving cam member generally designated by the numeral 46 as is shown in both Figs. 2 and 3. The cam member 46 includes a rotatable central shaft member 47 to which is eccentrically secured another element 48. Disposed about the cam eccentric 48 is an internal bearing retaining ring 49 upon which a plurality of balls 5i) ride. The operating surface of the cam member 46 is in the form of an outer retaining ring 51. Secured to the ring 51 is a radially extending arm 52 on the outer end of which is mounted a roller 5?- movable vertically in a guide slot formed in the fixed support structure.

Means not shown in the drawing such as a synchronous type motor is ordinarily used to rotate the shaft member 47. Obviously rotation of the shaft member 47 and of the eccentric member 48 which is integrally movable therewith imparts a cyclic camming action to the ball bearing 49, 5t 51 and causes the outer ring 51 to exert a thrust which can be applied, for example, to the ball followers 54 and 55, so as to exert a thrust to the left and to the right. ()uter ring member 51 does not rotate due to the action of the radially extending element 52 and the roller 53 mounted thereon. If desired the elements 52 and 53 may be omitted.

Disposed for respective engagement with the balls 54 and 55 are the thrust means 56 and 57. The thrust means 56 and 57 are of a tapered or wedge shaped construction and, being transversely disposed relative to the direction of reciprocation to the left and the right of the balls 54 and 55, can be used to inversely vary the contact opening and closing parts of each revolution of the cam member as will be more fully explained. Cooperatively disposed with respect to the thrust members 56 and 57 are the balls 58 and 59 and the reciprocating contact operating rods 60 and 61 that variably engage respectively with the contact members 31 and 32 so as to move those contact members to the open circuit position against the bias of their respective biasing means 37 and 38 during a variable part of each revolution of the cam member 46.

In order to regulate the position of the thrust members 56 and 57 in the vertical direction and thereby to control the contact dwell time in accordance with this invention, the thrust members 56 and 57 are pivoted respectively at 62 and 63 to the vertically movable rod members 64 and 65 which are biased downwardly by the spring means 66 and 67 respectively. Rod 64 is pivotally connected by lost motion means at 63 to a pair of cross arms 6? which in turn are pivotally mounted at 70 to a laterally movable pivotal support and at their righthand ends are provided with openings 76a in which is mounted a rotatable shaft 71 on which is mounted an eccentric member 72. Since eccentric member 72 is afiixed to the shaft 71, rotation of shaft '71 will impart vertical motion to the rod members 64 and 65 as will be obvious from Fig. 1. As is shown in Fig. l, the rod 65 is pinned at the lost motion pivotal connection 73 to the pair of transversely disposed operating rods 74 which are pivoted at 75 to the fixed support structure and which are provided with large openings 76 which cooperate with the eccentric 72 and its shaft 71 to impart vertical motion to the rod member 65. Thus, it will be seen that rotation of the shaft 71 eifectively imparts up or down adjusting or positioning motion to the thrust members 56 and 57 and thereby regulates the instant at which the contact members 31 and 32 are respectively opened and closed during each revolution of the cam member 46 so as to regulate the so-called dwell or closed time during each cycle of opening and closing of these contacts. It will be understood that in order to obtain suitable operation the contact operating rods 60 and 61 would preferably be biased into engagement with the balls 58 and 59 respectively.

Such bias for the rods 66 and 61 is shown at 76a and 77 in Fig. 3, while guide means 78 and 7 9 are respectively provided for the ball members 58, 54, 55 and 59. Also from Fig. 3 it will be seen that suitable sleeve-lilac supports for the thrust rods 64 and 61 are provided in the form of the fixedly mounted elements 80 and 81. It will be understood that at least a portion of the thrust rods 60 and 61 should be constructed of insulating material such as the parts 82 and 83 which are respectively mounted in the metallic portions 84 and 85 of the thrust rods 60 and 61 respectively.

As shown in Fig. 3, the revolving cam member 46 is in an angular position to exert a thrust through the ball 55, the tapered thrust element 57, the ball 59, and the push rod 61, so as to move the insulated end 83 of the push rod between the fixed switch contact elements 20 and 28 into engagement withthe movable bridging contact 32 and thereby move contact 32 from its predetermined circuit closing position to which it is biased by the spring 38. The distance that the bridging contact 32 is moved away from its circuit closing position will determine the length of the contact opening period and will depend upon the transverse adjustment of the tapered thrust element 57 due to adjustment of fulcrum 63. The farther the contact is moved away from the stationary contacts, the longer the contact opening part of each cycle will be and vice versa. Correspondingly as cam member 46 revolves to its diametrically opposite angular position from that shown in Fig. 3, the push rod 61 will move out of engagement with the bridging contact 32 a lesser or greater distance, thereby respectively decreasing or increasing the contact closing part of each revolution of the cam element. Thus upon shifting the reciprocating range of the push rod by adjustment of the fulcrum 63 of the oscillatory element 57, the contact opening and closing parts of each revolution of the cam 46 can be inversely varied.

From Fig. 3 it will be understood that the cam member and associated structure already described in connection with Figs. 1 and 3 is mounted within a metallic support plate member 85 which is supported on the frame members 86 and 87 in any suitable manner. The frame members 86 and 87 are secured in position and supported by the supporting frame members 88 and 89.

As will be seen from Fig. 3, biasing springs 66 and 67 are retained in position by the bracket members 90 and 91 which are secured by bolts to the supporting plate 85.

The bias for springs 37 and 38 is adjustable by means of the adjusting bolts 92 and 93 and parts associated therewith which structures are respectively mounted in the insulating supports 94 and 95 which are secured to the frame members by the bolts 96, 97, 98, 99. These bolts are respectively insulated from the current carrying elements by means of insulating tubes 190-403.

The alternating current buses 16a and 16b which lead from reactor 8 to the contacts 19 and 20 respectively and the direct current buses 4 and 5 and parts associated therewith are insulated from the frame members 86 and 87 by insulating means 104 and 105.

The thrust members 56 and 57 are individually adjustable by means of the adjusting nuts 1G6 and 107 and are held in position respectively by their locking nuts 108 and 109. Adjusting nuts 106 and 187 cooperate with transversely disposed members 110 and 111 which respectively interconnect the pair of transversely disposed operating members 69 and 74 as is best shown in Fig. 2. Thus, by

means of the nuts 1% and 107 the thrust members 56 and 57 may be elevated or lowered independently of each other.

From the description thus far it will be understood that the thrust members 56 and 57 are jointly adjustable during operation of the rectifier simply by rotating the shaft '71. Rotation of the shaft 71 may be by suitable manual means such as is indicated in Fig. 2 by the numeral 112. After suitable adjustment of the rotatable member 112, which is integrally secured to the shaft 71, the member 112 may be afiixed in position by the locking bolt 113 as shown in Fig. 2. It will also be understood that instead of the manual means 112, suitable automatic means such as an electric motor, could be used to rotate the shaft 71 and that such a motor could be made responsive to the magnitude of current being delivered by the rectifier or supplied thereto. In such a construction it will be appreciated that the rectifier would be fully automatic and would respond to the magnitude of load current in such a way as to adjust the dwell time of the contacts to accoma"! modate changes in the magnitude of the load.

The modification of my invention as shown in Figs. 4, 5 and 6 is essentially like the arrangement shown in Figs. 1, 2 and 3 except that the arrangement of Figs. 4, 5 and 6 does not incorporate the ball members 54, 55, 58 and 59 shown in the modification of Figs. 1, 2 and 3 and in addition the means for adjusting the thrust members, such as 56 and 57, is different in the two modifications.

Furthermore, the arrangement of Figs. 4, 5 and 6 shows the bolting means and 116 for respectively securing the D.-C. buses 4 and 5 in position and the bolting means 117 and 11% for securing the alternating current bus structures in position.

In order to support the thrust adjusting regulating means in the modification of Figs. 4, 5 and 6 plate members 119 and 12B are respectively secured to the top of the unit by the bolts 121 and 122, and a horizontally disposed cross piece 123 is secured to the uprights 119 and 12% by means of the bolts 124.

As in the modification of Figs. 1, 2 and 3 the arrangement of Figs. 4, 5 and 6 is constructed so that each thrust member, such as 56 and 57 may be adjusted individually through adjusting screws 125 which are locked in position by the lock nuts 126. The adjusting screws 125 are mounted in the adjusting plate 127 so that when plate 127 is moved vertically all the tapered thrust transmitting members such as 56 and 57 are moved in unison. In order to insure that each of the thrust transmitting members will move the same amount it is necessary to insure that the adjusting plate 127 is movable in the vertical direction without any wobbling effect. In order to prevent wobbling of the adjusting plate 127 the vertically disposed elements 129 are rigidly secured in position to the top plate 123 by means of the nuts 130 and are screwed into the support structure at their lower extremities as indicated at 131. Mounted about and slidable along each of the members 129 is a sleeve member 132 which, in turn, is affixed to the adjusting plate 127. Thus, it will be understood that by the sleeves 132 cooperating with the vertically disposed guide rods 129, the adjusting plate 127' is prevented from wobbling.

Vertical adjusting motion of the adjusting plate 127 is imparted by means of the rotatable adjusting bolt 133 which threadedly engages a sleeve member 134 rigidly secured in position in an opening in the adjusting plate 127. Vertical motion of the adjusting bolt 133 is prevented by the collar assembly comprising the collar memher 135 which is secured against vertical movement by the clamping ring 136 and the upper plate member 123 and due to engagement of the collar member 135 with the portion 137 of the adjusting bolt 133. As will be seen in Figs. 5 and 6, the adjusting bolt 133 is provided at its upper extremity with a suitable construction 138 such as a hexagonal periphery for cooperation with a suitable adjusting wrench to be operated manually.

From the description thus far it will be understood that rotation of the vertical adjusting member 133 as by a wrench will result in vertical movement of the adjusting plate 127 which, in turn, will impart vertical motion to the tapered thrust transmitting elements 56 and 57 and thereby will control the dwell time of the contacts of the rectifier. It will also be understood that instead of a manually operable wrench as a means for driving the adjustable bolt member 133 such element could be rotated by motor means which, in turn, could be responsive to the magnitude of direct or alternating currrent through the mechanical rectifier and in such a way the rectifier would be automatically adjustable during operation insofar as the contact dwell time is concerned in response to variations in the magnitude of the load current.

While I have shown and described particular embodiments of the invention, I do not wish to be limited thereto and intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. In combination, a rectilinearly movable switch member having a pair of spaced apart fixed contacts bridged thereby, a revolving cam member having its axis spaced on the opposite side of the fixed contacts from said switch member, means biasing said switch member to move toward said cam member into engagement with the fixed contacts, and thrust means including a reciproeating contact operating member having one end extending between the stationary contacts and an adjustable oscillatory element interposed between the other end thereof and said cam member for causing said switch member to open during a variable part of each revolution of said cam member, said oscillatory element having a fulcrum adjustable relative to the axis of the cam member for shifting the reciprocating range of the contact operating member so that adjustment of said fulcrum inversely varies the switch opening and closing parts of each revolution of said cam member.

2. In combination, a rectilinearly movable switch contact having a pair of spaced apart fixed contacts bridged thereby, a revolving cam member having its axis spaced on the opposite side of the fixed contacts from said movable switch contact, means biasing said movable switch contact to move toward said cam member into bridging engagement with the fixed contacts, thrust means including a reciprocatory member having one end engageable through the space between the stationary contacts with said bridging switch contact and an adjustable oscillatory element interposed between the other end thereof and said cam member for disengaging said movable switch contact from said fixed contacts during a variable part of each revolution of said cam member, means biasing said reciprocatory member to move out of engagement with said bridging switch contact and into engagement with said oscillatory element, and said oscillatory element having a fulcrum adjustable relative to the axis of said cam member for shifting the reciprocating range of said reciprocating member to inversely vary the switch contact opening and closing parts of each revolution of the cam member.

3. In combination, a reciprocating electric switch contact having two spaced apart fixed contacts bridged thereby, means biasing the reciprocating contact into bridging engagement with the fixed contacts an aligned reciprocatory member operable through the space between the fixed contacts to disengage the reciprocating contact from the fixed contacts, a cam member revolving at constant speed and having its axis disposed in line with the reciprocating path of the reciprocatory member, means biasing the reciprocatory member to move out of engagement with the reciprocating switch contact and toward the cam member and a tapered oscillatory wedging member interposed between said cam and reciprocatory members and having pivotal mounting means at one end thereof adjustable transverse the direction of reciprocation of the con- 7 tact engaging member for shifting the range of reciprocation thereof to inversely vary the opening and closing parts of each revolution of said cam member.

4. Cyclic mechanism having in combination a movable contact having spaced apart stationary contacts in cooperating circuit controlling relation therewith, means biasing the movable contact into bridging engagement with the stationary contacts and a revolving cam member having a cam follower assembly for opening the bridging contact during a variable part of each revolution of the cam member and including an oscillating member engaging the cam member and a reciprocating push rod having one end biased into engagement with the oscillating member and the other end insulated and extending between the stationary contacts for engaging the bridging contact to effect opening thereof, said oscillating member having an adjustable fulcrum for shifting the reciprocating range of the push rod to inversely vary the contact opening and closing parts of each revolution of the cam member.

5. A periodic circuit opening and closing switch mechanism having in combination, a pair of spaced apart fixed contacts, a rectiiinearly movable bridging contact therefor having means biasing the bridging contact intocircuit closing engagement with the fixed contacts, a revolving cam having means operated thereby including a push rod reciprocated between the fixed contacts into engagement with the bridging contact for periodically disengaging the bridging contact from the fixed contacts, and means including a pivoted oscillating element interposed between the revolving cam and the push rod and provided with an adjustable pivot for shifting the reciprocating range of the push rod to inversely vary the bridging contact circuit opening and closing periods upon adjustment of said pivot.

6. In combination, a switch mechanism comprising .a pair of fixed contacts in spaced apart alignment and a rectilinearly movable bridging contact therefor having spring means engaging one side of the bridging contact for biasing the bridging contact into circuit closing engagement with the fixed contacts, a revolving cam having means operated thereby including a push rod reciprocated between the fixed contacts into engagement with the other side of the bridging contact for periodically disengaging the bridging contact from the fixed contacts, and means including a pivoted oscillating element interposed between the revolving cam and the push rod and provided with an adjustable pivot for shifting the reciprocating range of the push rod to inversely vary the bridging contact circuit opening and closing periods upon adjustment of said pivot.

7. A periodic circuit opening and closing switch mechanism having in combination, a pair of spaced apart fixed contacts, a rectilinearly movable bridging contact therefor having spring means biasing the bridging contact into circuit closing engagement with the fixed contacts, a revolving earn having an axially aligned push rod reciprocated thereby between the fixed contacts into engagement with the bridging contact for periodically disengaging the bridging contact from the fixed contacts, and means including a tapered oscillating element interposed between the revolving cam and the reciprocating push rod and provided with a pivot adjustable transverse the direction of reciprocation of the push rod for shifting the reciprocating range of the push rod to inversely vary the bridging contact circuit opening and closing periods upon adjustment of said pivot.

References Cited in the file of this patent UNITED STATES PATENTS 1,480,546 Cummiskey Jan. 15, 1924 1,812,647 French June 30, 1931 2,375,416 Huber May 8, 194-5 2,490,523 Kneisley Dec. 6, 1949 2,556,716 Viol June 12, 1951

Images