US1635581A - Ward g - Google Patents

Description

Patented July 12, 1927.

UNITED STATES PATENT OFFICE.

JOSEPH W. MEADOWCROFT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO ED- WARD G. BUDD MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA,

A CORPORATION OF PENNSYLVANIA.

ELECTRIC SWITCH.

Application filed January 18, 1922.

My invention relates to improvements in electric switches and concerns, more particularly, switches of that class adapted for use in connection with electric welding machines, but is not restricted to such use as it may be used in any connection for which it may be adapted or appropriated.

One of the objects of my invention is to provide an electric switch mechanism which is very durable and etlieiont, even when the switch is used in situations which require that it be operated very rapidly and substantially continuously, and which has a long life so that the need for replacen'ient or repair of the switch parts is greatly lessened.

.A further object of my invention is to provide a switch construction which will withstand very successfully the destructive or deteriorating effects of rapid and continuous operation.

Another object of my invention is to provide means for carrying off the heat generated in' the switch contacts by the passage of the current so as to prevent undue heating ofthe Working parts of the switch.

Another object of my invention is to provide simple and effective means by which the contacts of an electric switch may be renewed very quickly and easily.

A further object of my invention is to provide an electric switch having means for cooling the switch contacts.

Further objects, and objects relating to details and economies of production and operation, will definitely appear from the detailed description-to follow. In one instance, -I accomplish the objects of my invention by the devices and means described in the following specification. My invention is clearly defined and pointed out in the appended claims. A structure constituting a preferred embodiment of my invention is illustrated in the accompanying drawings, forming a part of this specification, in

which Fig. 1 is a perspective view of the head and a portion of the operating lever or" an electric welding machine, showing a switch embodying my invention applied thereto.

Figure 2 is a longitudinal sectional View through the switch,

Figure 3 is a plan view of said switch, and

Serial No. 530,070.

Fig. 4 is a longitudinal, sectional View through one of the switch contacts.

In the drawings, the same reference numerals refer to identical parts throughout the several views.

In the pending application of Joseph Ledwinka for Letters Patent for automatic electric welding machines, Serial No. 430,320, filed December 13th, 1920, there is illustrated an electric welding machine which is used to produce, automatically, a series of spot welds in the work placed or fed between the electrodes ot the machine. This machine comprises a standard having a lower arm, carrying a fixed electrode, and an upper arm in which a plunger, carrying a movable electrode, is slidably reciprocated, to cause the movable electrode to approach the fixed one, by a. two-part operating lever. The inner part of the operating lever is fixed to a shaft, which is connected to the plunger by a toggle link, and the outer part of the lever is pivoted'to the inner part. The two parts of the lever are held yieldingly in line with each other by suitable spring means. The welding circuit is controlled by an automatic switch in which the closing and opening of the circuit is determined by the relative positions of the two parts of the operating lever so that, when the movable electrode exerts a predetermined pressure on the work, the contacts of the switch move into engagement with each other and the welding circuit is'closed, and, when this pressure is increased a predetermined amount, the contacts automatically move away from each other and the circuit is opened. The outer part of the operating lever is connected by asystem of links and levers with a reciprocating pitman which is driven by an electric motor. The'operating lever is, consequently, actuated or oscillated rapidly, for instance, in actual practice, at a rate of about 120 strokes per minute.

I have found that the automatic switch, in a machine such as described, has a very short life and needs much repairing and replace seat of parts in order to keep it in operating condition. The copper contacts Wear down very quickly and have to be renewed and the insulating fibre burns out and lets the parts of the switch work loose, resulting, frequently, in broken parts. The renewal of mounted. This plunger is .ti l, 91! d ea h'e'sl in the It is among the special purposes of my invention to provide a switch which is devoid of these objections and which will require very little repairing or replacement of parts, in other words a switch which has a long life, even when operated under such trying conditions as described above.

My invention consists in providing means f r c'ooling-the switchcontacts so as to carry V enerated by the passage of the current and y arcingand prevent the transmission of such heat to the working parts of. the switch. may accomplish this by using hollow switch contacts connected in a llive Sy tem 0 t at a. o l ng fluid y be circulated therethrough. 'llhe body of the switeh contactn ayhave a cooling chamber therein provided withan inlet and an outlet, the i'i letsand outlets of the various contaatsi liq ag qa eae q.t t-su a e. eech i that a coolinw' jed u'm maybe circulated Wa h them- T i ei oate ts'e e r id d-with ma able slan e b -t d ta a'bly connected to the body of the contact,

- so, that they may be removed without distu b ng t e atter;-

r5191: e pla umy inyent I a illustrated an automatic switch suitable for we in el tr c 'w li'l fi gmslunssand c e u i ins m od m n' at i e t en My invention, however, not'to-ibelimited :or nestricted tp a switch'of type as itl will finduse application inswltches' of, many ther'types. Inthe drawings accompanying this speciticati0 i,-I,"l1a,ve" illustrated an automatic switch construct-ion applied to an electric welding-machine, which switch embodies my invention. Referring to the numbered parts of t l e.dra,wing, I haveshown the head. 10, of; anhelectri'c welding machine, which head 1 1, in which s 'ournafd a, shaft, 12, connected by the toggle 111;, 13, with the plunger of the machiiie czgggy ingtlie in yableeleetrode. This aft-Z.) .1 afiq llflted; .8" m ans. of a -p i-at ire I -'.Qeim s ea the i n P 1, Y,l11( 5,l 1.,lS fiXQd on the shaft, 12, and the e te pa t, 115,-. the'inper. p t The lever may b a tuated qro'sc' l lated either by hand or auto matical iy' q y' st amer ina lever ws a-" e m P n ing- 1 wh n to whic v Pr viously referred, or by other suitable mech- 32. A pair of tensionsprings,

\ v,hich is pivoted, at 16, to

anism. The inner part, 14, of the lever is channcl-shaped so that a portion of the outer part, 15, lies within this channel. The two parts, 1% and 15, of the operating lever, are yieldingly held in alignment with each other by means of a spring, 19, interposed between the outer end of the part, 14;, and athumbnut. 20, screwed on the end ot' a rod, 17, which extends through the inner part, 14, and ispivotally connected to the outer part, 15, of the lever, 18.

A contact-carrying arm, 22, is pivoted at 21, to the inner part, 14, of the operating lever and carries a pair of contact-clamping members, 23, which are insulated from each other and from the operating parts of the switch. Each of these contact-clamping members, 23, carries a switch contact, 24:, detachably secured therein by means of the set screws, 28, and electrically connected at with a lead, 26, connected in the welding circuit. The pivoted arm, 22, is provided with the rearwardly extending portion,- 29, which engages beneath a lug or shoulder, 31, formed on an overhanging portion of the inner part, 14, of the lever. A spring, 30, engaging this portion, 29, holds it against the" stop shoulder, 31,'so as to determine the forward position of the contacts, 2%. It will b'e seen that this arrangement permits the contacts, 2 1, and the arm which carries them to move rearwardly, against the pressure of spring, 30, when engaged by the onposing contacts of the switch.

.An arm, 32, is also pivoted to-the inner part, 14, ofthe operating lever, at 33, and carries a contact-clamping member, in which a pair'ot contacts; 35, are detachably securedby-the set screws, 36: The contacts of this pair are electrically connected to each otherand, when the contacts, 24, previously described, thecircuit will be closed, 'A- link, 38, is pivoted to the part, 14, ot "the operating lever, by the pin, 15, "'d theupper end of said-link t 'pivotally c onnectedbya" pin,-54, to the they are '1I 1 engagement with rearends of a pair of parallel links,39, the

forward ends of whichjar'e pivotally connected by the pin, 40, to the swinging arm, 41, have their forwfard ends, connected to the pin, 40,- and their rear ends connected, at 42', to the fixed standard, 43. A housing, 4 1, has a downwardlyeexte nlding leg which is pivoted on the pin, 45,;and: another "downwardly-extendingleg, 46, at the forward end thereof, which is adapted to engage the part, 14, of the operating lever in or der to limit the rocking movement of the. housing, 44, around its pivot, 45, plunger, 47', works Within the'housing, '44, and has a stem, 48, which extends through the bottom of therhousing andis connected to the part, 15, of theope rting lever, by a link, 49, extending through the part, 14, and pivotally connected to the part, 15, at 50. A coil spring, 51, is placed within the housing, 44, between the base thereof and the plunger, 47, as shown in Fig. 2. The upper face of said plunger has a tooth, 52, formed therein which coacts with a pawl, 53, pivoted on the pin, 54, and yieldingly pressed into engagement with the plunger-by a. spring, 55.- \V hen a downward pull is exerted on the outer end of the outer part, 15, of the operating lever, the two parts of the lever move as one until the upper electrode of the welding machine engages the work. The resistance offered by the work to'the further movement of the movable electrode causes the outer part, 15,

of the lever to swing on the pivot, 16, relative to the inner part, 14, against the pres sure of the spring, 19. This swinging movement of the outer part of the operating lever, causes thehousing, 44, to swing on its pivot, 45', since it is connected with the outer part, 15, of the operating lever through link, 49, stem, 48, plunger, 47, and coil spring, 51. During this stage of the movement, the link, 38, is compelledto' swing on the pivot, 45, with the housing, 44, since the pawl, 53, hooks int-o the tooth, 52,;of the plunger, 47. The forward swingingmovement of the link, 38, swings the arm, 32, -forwa rd, due to the links, 39,. connecting, the link, '38, and the arm, 32, and the contacts, 35, are brought intoengagement with the contacts, 24. This swinging movement of arm, 32, puts the springs, 41,under tension: 'A-further swinging moven entof housing, 44,isprevented by the contact-of the foot,.46, with the part, 14, of; the operating-Jeyer' and, a ,further movementof-lthe outer part, :15, of the operating lager; around ii.ts.,pivot', 16, compresses the spring 51, and; depresses the plunger, 47, withdrawin ith ieitooth,-52, thereof from engagement with thetpawl,.53, and breaking the connection betweemthe housing, 44,,and the lin k,.38, so that-the arm, 32 is freeto fly backward, influenced by the tension of springs, 41, carrying the contacts, 35, out of engagement with the contacts, 24, and opening the welding circuit.

Each of the contacts, 24 and 35, in this switch, has a chamber, 56', in the body portion thereof, and an inlet and outlet, 57 and 58, communicatingwithsaid chamber. These inlets andoutlets areconnected by suitable conduits or tubes, 60, 61, 62, 63 and 64, so that. a suitablecooling medium may be circulated through the various chambers, 56, of

the severalcontacts. The tubing is preferably arranged so that these chambers are connected in series and the cooling medium, for instance, cooling water. may flow in through the tube, 64, and the inlet, 57', to the chamber, 56, of one of the contacts. 24, out through the outlet, 58, and tube, 63, to the inlet,'57, of the chamber, 56,- of one of the contacts, 35, from thence through the tube, 62, to the chamber, 56, of the other contact, 35, from thence through the tube, 61, to the chamber, 56, of the remaining contact, 2'}, and from thcncc through the tube, 60, to the discharge. The contacts are all pi-a-Yided with removable contact points or ends, 37, each of which has a screw-threaded stem, 59, screwed into the body portion of the contact, as shown in Fig. 4. As these contact points or ends become worn down in use, they may be removed very quickly and easily by unscrewing them from the body portion of the contact and they may be replaced by new points or ends.

I have found that, by the use of a cooling system for the switch contacts, as described above, the objectionable features heretofore noted in the operation of the switch, particularly at high speed, are eliminated. The switch does not break down in use and it is practically unnecessary to repair or replace the operating parts, with the exception of the contacts, which, of course, wear down in use. I find, however, that the life of these contacts is about twice as long as the life of the contacts formerly used and I believe this to be due to the fact that a large part of the heat generated in the contacts iscarried away by the coolingsystem. Notpnly is the life of the contacts prolonged due to the carryin away of the generated heat, but also to a large extent to the resistance and ca pacity shunt circuits which actually out down the arcing at the contact points themselves. These circuits, are those formed, respectively, by the series water circuit from one contact-ofthe gap to thejotherthrough the ,bridging. contact points, and by ,the water supply -connection connecting with one terminal and the, water discharge connection leading from the other terminal connecting with the sewer. I also find that my im- 'proved switch is so eliicient and so superior to the switch heretofore used, that I may-increase thespeed of the automatic welding machine very greatly, so as to get, approximately, 30% more welds per minute with it. This results in increased production at lower cost and, of course, is very desirable. As I have stated, the contact points necessarily wear down in use and, in order to avoid the necessity for disconnecting the contacts and the connections for the cooling system, I have provided the removable contact points or ends which are detachably secured to the body portions of the contacts and may be removed very quickly and easily and replaced by new points or ends.

My invention has proven of considerable value in electric welding machines, especially those that are operated automatically and consequently at high speed. However, this invention is applicable to other-electric switches and, therefore, I am not to be re-, stricted to the details of the particular switch mechanism illustrated or to a switch used in connection with an electric welder. I am aware that the embodiment of my invention, illustrated in the accompanying drawings, may be varied considerably without departing from the spirit thereof and, therefore, I claim my invention broadly, as indicated by the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. An electric switch comprising a plurality of pairs of contact members movable into and out of contact with each other, means for moving said members, and means for continuously circulating a cooling fluid in heat transferring relation to and through said contact members in series.

2. In an electric switch of the class described, a pair of contact members elect-rically and mechanically connected together, a second pair of contact members mechanically connected together but insulated from each other, said pairs of contact members being movable into and out of contact with each other, and means for continuously and uninterruptedly circulating a cooling fluid successively through each of said contact members.

i 3. In an electric welding machine includ ing a primary circuit' therefor, pair of spaced apart contact members in one side of said circuit, aseeond' pair of contact; members electrically" connected together and adapted to bridge said-first pair of contact members, and means for circulating a cooling'fi'nid through -said contact members in succession beginning with one of said elec trically spaced"apart-'icontact members and ending with the-other of said 'ele'ctrical-ly spaced aparfcontact members.

4L In ani'electfric sjwitch of the class described, a pair oficontact members rigidly connected" together but insulatedfrom each other, a second pair of contact members rigidly and electrically connectedtogether, said second mentioned pair of'contact membersbeingadapted to b'ridgesaid first mentioned pair of contact mer'nbersfand a circulating cooling system having its source connected to one or said electrically insulated contact members audits =outl et con- .nected to the other of said electrically insulate d contact'members.

- 5: In an electric. switch of the class described, a plurality of contact members, a p ir of ports 'ineach'. of. said contact members, certain of said contact members being electrically connected together and the remaining of said contact members being in sulated from each other, means connecting a port in one of said electrically connected contact members to a. port in the other of said electrically connected contact members,

and additional means connecting the other ports of said electrically connected contact members to corresponding ports in said electrically insulated contact members, respectively, whereby to effect a complete circulating system for a cooling medium.

6. A power control system comprising a circuit of high voltage, a power consuming device, a circuit breaker cont-rolling the supply of power thereto, and a column of conducting fluid of relatively high resistance circulating through the terminals of said breaker in series whereby the arc between the terminals is moderated by the resistance shunt so maintained and the heat of the arc is conducted away by the fluid column.

7. A power control system comprising a circuit of high voltage, a power consuming device, a circuit breaker controlling the supply of power thereto, and a column of water supplied through the grounded mains and discharged to grounded sewers circulating through the terminals of said breaker whereby parallel paths of resistance and capacity are'introduced therebetween.

8. A power control system comprising a source of high voltage, a power consuming device comprising the primary of an electric welding transformer, a circuit breaker controlling the supply of voltage to said primary, and a column of conducting fluid of relatively high resistance circulating through the terminals of said breaker in series whereby the are between the-terminals is moderated by the resistance shunt so maintained and the heat of the arc is conducted away by the fluid column.

9. A power control system for electric welding machines comprising a welding transformer having primary and secondary circuits, welding electrodes permanently connected in said secondary circuit, and a circuit breaker automatically operated in the functioning of the m'a'chine tomake and break the primary circuit "for each weld made together with a circulating columndfelectrically and heat conductive fluid flowing through the terminals of the circuit breaker in series.

10. power control system for electric welding machines comprising a welding transformer having a primary circuit of relatively high voltage and a'secondarycii cuit of relatively low voltage, welding electrodes permanently connected in said secondary circuit of low voltage, a circuit breaker operating continuously durin the operation of the machine to connect and disconnect the primary circuit from the source of power, and a column of water circulating through the terminals of said bre'alrer in series.

In testimony whereof, I afiix my signature.

JOSEPH- W. MEADOWCBOFT.

Images