US2520441A

US2520441A - Switch

Info

Publication number: US2520441A
Application number: US14600A
Authority: US
Inventors: Fred C Schwaneke
Original assignee: DORMEYER CORP
Current assignee: DORMEYER Corp
Priority date: 1948-03-12
Filing date: 1948-03-12
Publication date: 1950-08-29
Anticipated expiration: 1967-08-29

Description

Aug. 29, 1950 F. c. scHwANEKE 2,520,441

SWITCH Filed March l2, 1948 Patented Aug. 29, 1950 SWITCH n Fred C. Schwaneke, Chicago, Ill., assignor to Dormeyer Corporation, Chicago, Ill., a corporation of Illinois Application March 12, 1948, Serial No. 14,600

9 Claims.

This invention relates generally to electrical switches and more particularly to an improved nonarcing slow acting switch.

The switch of this invention is particularly well adapted for use in the line circuit of fractional horse power motors equipped with variable centrifugal speed governors, but it may also be used for any other purpose where similar mechanical limitations make the use of a quick acting snap switch impossible or undesirable.

One object of this invention is to provide a slow acting switch which may handle relatively heavy alternating or direct currents without appreciable arcing at Vthe make and break contact points.

A second object is to provide a switch in which the contact points are enclosed in a hollow sleeve member which excludes oxygen therefrom and reduces arcing.

Another object is to provide a switch in which the contact points are open to the atmosphere while the switch is closed and sealed therefrom during the opening of the contacts and after they are opened.

A further object of the invention is to provide a switch arrangement in :which the member moved to break contactis heat insulated from the arc bearing contact so that a low melting point unbreakable thermoplastic s uch as polystyrene can be used to actuate the switch. n

A further object is totprovide a novel switch in which the contact points are enclosed `in a hollow sleeve, which sleeve serves the dual purpose of quenching the arc formed and forming a mechanical link between the actuator member and the movable contact.

Another object is to provide a switch arrangement wherein either a rotating or sliding cam surface may be employed to actuatethe switch.

Another object is to provide a novel switch and condenser arrangement whereby the condenser Y serves to absorb the surge of current as the switch is. opened to aid in the snulfing or are quenching action of the contact enclosing sleeve.

A further object is to provide a novel arrangement wherein a vline switch and a centrifugal In the drawing:

Fig. 1 is a perspective View of the switch of this invention viewed from a point below and to one side;

Fig. 2 is a top view of the switch;

Fig. 3 is a side view partly in section;

Fig. 4 is a view of a portion of the switch similar to Fig. 3 but with the switch in the opened position;

Fig. 5 is a section taken on line 5 5 of Fig. 3;

Fig. 6 is a section taken on line 6 6 of Fig. 3; and

Fig. 7 is a wiring diagram of the preferred electrical circuit.

The switch I6 is assembled on a base plate II of insulating material such as laminated phenolic. A projection I2 on the base plate II is provided for attachment of the switch Ill to any convenient surface such as a motor frame (not shown) Two holes I3 are provided for the mounting screws or bolts (not shown). The base plate need not have the shape shown but may be made in any convenient shape according to the installation requirements.

The base plate II in turn supports the rest of the various elements which make up the switch I0. A spacer block I4 also formed of insulating material is secured to the base plate I I by a pair of rivets I5 and supports the elements in the spa-ced relationship.

The stationary Contact point I'I, preferably of silver, is supported on the extending end of the plate Il as shown in Fig. 6. The shank portion I8 of the Contact Il isof lesser diameter than the rest of the contact and is surrounded by a hollow cylinder 26 or phenolic material which serves as a heat insulating spacer between the end of the contact Il and the mounting plate Il and also reduces the quantity of silver required. The end of the shank portion I8 is provided with a shoulder 2l and peened as at 22 to fasten it to the plate I I and to a lug 23 which forms the terminal of the switch I0.

The other contact point 25is supported on a spring member 26 by peenng its shank portion 21. The spring member 26 is supported on the spacer block I6 by the rivets I6 which hold the switch IIJ together. The member 26, which is formed of an elastic current conducting material such as beryllium copper or bronze, is slotted as shown in Fig. 2 to provide a centrally disposed mounting portion 28 the same width as the spacer I4. The side portions of the member 26 are offset slightly as shown in Fig. 3 near the ends of the slots 3D. An integral lug 3l on one side of the member 26 forms the second switch terminal.

A second elastic member 32 similar in shape to the spring member 26 is secured between the spacer block I4 and the base plate I I. The actu.`

3 ator member 32 instead of carrying a contact point is provided with a hole 33 (best shown in Fig. 6) through which the contact I1 extends. This hole 33 is preferably made as' smallas manufacturing tolerances will allow so as tojust clear the sides of the contact il.

A recess 34 is provided in the bottom of theV block I4, spaced from the rivets I5, for receivingY the central portion 35 of the member 32, A pair of small projecting lugs 36* integral? with the central portion 35 project int'oa painof holes 31- in the spacer block Irl to anchor the member 32 against lateral displacement. A' thin rectangular piece of insulating material having the same cross section as the spacer block I4 is rivetedbetween' the member 32 and the base plate to form a separator 39.

Theend of the member 32 projects beyond the base plate II and isslotted and bent to provide a cam follower surface 33 to move the end of the actuator member 321' away from the base-plate i when rotated tothe position shownin Fig. 4.

The shaft lt for the cam 4B is preferably journaled in the stationarymember (not shown) toV which the base plate I I is attached so that movement: of the cam ie relative to the switch I0 occurs as the *shaft tI-is rotated;

In some instances it has proved desirable toemploy a slidingrather. than-a-rotating cainto actuate the switch, depending on-the manner in which the .switch I is installedi In one application where the switch was employed as a line switch for a motor having a variable-speed-cen-Y triiugal governor the cam element for settingY the governor was provided withan additional cam surface orlug which bore against the surface 38- to open the switch I when the governor cam was-rotated to theoi positionacljacent the'lowest speed setting.

Disposed around the contact points'` H and 25 is` a cylindrical sleeve 45;' ofinsulating material. The sleeve l5-is preferably formed of'red'orblaclil fiber but may be-of phenolic material such as Bakelite or of ceramic. The only requirements are that the materialhave sumcient mechanical strength, be resistant to the hightemperatures which are encountered; and' be nonconducting.

rFheinside diameter of the sleeve `is slightly larger than the diameter of the Contact points to allowthem to become" slightly cocked with respect to each other whenfopened'and to provide sumcient manufacturing tolerance. The ends of the sleeve are slightly'beveled'or chamiered in-order to-removeburrs and prevent bind-l ing against the contact-points.

The length of the sleeve d isslightlyless than the distance between the

members

26 and 32 so that' either, or both; ends-are open to the atmosphere when the switch is closed; the'A sleeve 45- being loose and free to move with respect to the contacts ifi-and 25.

The mechanical operation oithe switch l) is as follows: )Inl the closed position the elementsV are positioned asl shown in Figs; 1 and 3. As the cam tli's rotatedto theposition shown in Fig. 4 itvstrilres against the follower surface 38 on theV end of the actuator member`32 and moves the actuator member S2 away from the plate I I; The end of the-member 32 movesireely until it strikes against the end of the* .sleeve t5A and ncves it towardlt'he member i2. At this point the movementis-transmitted through the sleeveY 45 to the member I2 causing'italso to be moved away from the base plate Ii: Sincethecontactv il isattached toy the base plate II andthe con-u 4 tact 25 is attached to the member I2, the two are separated, breaking the electrical circuit.

Since the breaking is relatively slow as comparedv withia snapkswitch; arcing occurs between t'hesilvercontact points" I1* and 25 when appreciable current is being carried by the switch I0. But the arc formed is coniined to the small annular space within the sleeve l5 for the ends of the sleeve 45 are tightly pressed up against the members-l |12I and- 325 with little, if any, opening t'othe atmosphere'. Thus the enclosed chamber around"tli`eV contacts'is of minimum size and virtually sealed oisothat oxygen is prevented from getting to the contact points to cause sustained oxidation of silver whichmay be vaporized. Any vapor generated merely recondenses on the contact points to, irreffe'ct, plate-them' with anew clearsurf ace fofl silver- Although it is diiilcult-v or impossible todoter-v mine what actually occurs as-thecontacts'break,

the fact that' the presence of f oxygen` around the contacts` isV greatly minimized andinfluxf of atmospliere` isvirtuallysealedy outvthere is a com'- binationofl snuiling" out thevarc and some acceleerationlof contact separationdue tothe explosive eiiect of` gas Iformed assisting' the cam in. opening the contacts.

By making the sleeve 45-shorter thanthefdistance between the members 2B and 32 several advantageous resultslare obtained. First, opening of the switch contacts does not occur until'- the caml40 hasbeen turned through a considerable arcwithsufcient force to movethe spring actuator member 322 rIfhisinsuresthat a-faster speed of break between the contacts I-T and' 25 will occur thanifV the contacts started to separate as soon as the cam 401 was rotated; This is particularly true wherek the cam 4I!"4 is manuallyI moved since starting friction'will already haveA Secondly, the contactsA I-'IY andbeen overcome. are opened to the air 'during the time when the switch-is vclosed and Vhence cool more'rapidly, particularly if a fan islrunning, than if theyL were always confined within the/sleeve.

As stat'edfpreviously,V the switch I0 is particuy both sw-itchesV IUandA-"L The motor armatureis` connected=to oneend of the-serieseld46 and'to the linewhile the other endof'l the field isconnected to-the other side of the line. A T pad' of condensers-SI, 52'and53 is connected across-the line and to the motor casing for purposes of eliminating radio interference from the motor and switches I0 and ,FI`Y while the appliancev isl being handled.

The location of the switches between thehal'ves ofthe iieldy 4G" and the shunted condenser 501 eliminates a largeV proportion' of the radio interference, but the addition of the T pad of condensers? has-proved' desirable in mostl instance to further minimize it;

The use ofy a shunted condenser across: the switch-where -theswitchJ is usedto control anni-- versallseries motorachievesaY novel result which serves tofgreatly'increase thel life yof the/switch:-

When the proper sized condenseris provided for`v afv given switch' and motor*l combina-tion; the time of discharge of the condenser can adjusted that, as the contacts are separated, the condenser charges, absorbing the inductive reactance of the series field. This serves to reduce the arcing to a minimum value during the first stages of the separation of the contacts. As soon as the contacts have separated a predetermined distance and the condenser has been sufficiently charged, an explosive arc occurs which drives the movable contact away from the stationary contact and completely breaks the circuit. This action is made possible by the cylinder and piston-like arrangement of the sleeve and contact.

For a fractional horse power governor controlled series motor which drew .4 of an ampere at 115 volts D. C. under load a condenser having a capacity of .05 mid. was used to achieve the `above result. This motor and switch combination successfully stood up under a series of over one hundred openings and closings of the line switch with the armature of the motor blocked against rotation and a voltage of 120 volts D. C. applied. The successive makes and breaks of the switch were spaced six seconds apart in this test.

Various changes or modifications such as will be readily apparent to those familiar with the art may be made without departing from the spirit of this invention whose scope is defined by the following claims.

What is claimed is:

1. A switch comprising a xed contact, a cooperating movable contact, resilient means for urging said movable contact towards said fixed contact, a resilient actuator for separating said contacts disposed adjacent to said xed contact, and

an insulating sleeve element enclosing said conf tacts, the ends of said sleeve bearing against the actuator and the resilient member to open the contacts when the actuator is moved toward the movable contact.

2. A switch comprising an elongated insulating base plate, a contact supported on one end of said plate, a resilient actuator member supported on the opposite end of said plate and extending parallel to said plate to a point beyond the end thereof, an opening in said actuator through which the contact extends, a resilient member supporting a second contact in cooperating relation with said iirst mentioned contact, a bearing surface on said second member near the contact, and an insulating cylindrical sleeve element closely surrounding said contacts for quenching the arc formed as said contacts are separated and for imparting motion of said actuator to said resilient member to separate said contacts when the end of said actuator is moved away from said plate, said sleeve element bearing against said bearing surface to move said resilient member.

3. In a switch the combination including a fixed contact, a cooperating movable contact carried by a flexible member, a loose fitting sleeve member surrounding said contacts and being shorter than the combined length of said contacts and an actuator surrounding the base of said xed contact and being movable with respect thereto for bearing against one end of said sleeve member to move it along the axis of said fixed contact, the other end of said sleeve bearing against said flexible member to open said contacts as said `actuator is moved.

4. In a switch the combination including a pair of contacts, a cylindrical loosely tting sleeve enclosing said contacts and being shorter than the combined length of said contacts, and an actuator Surrounding the base of one of said contacts and movable with respect thereto, said actuator bearing against one end of said sleeve to seal the opening between the side ci the sleeve and said contacts when said switch is in the open position.

5. A switch comprising a fixed contact, a cooperating movable contact, a movable actuator for separating said contacts surrounding the fixed contact, and an insulating movable sleeve enclosing said contacts, said actuator member bearing against one end of said sleeve member and closing the opening in the end of the sleeve when said contacts are separated.

6. In a switch the combination including a fixed contact supported on a base plate, a cooperating movable contact carried by a ilexible member, a loose fitting sleeve member surrounding said contacts, and an actuator surrounding the base of said fixed Contact for bearing against one end of said sleeve member to move it along the axis of said fixed Contact away from said base plate, the other end of said sleeve bearing against said flexible member to open said contacts as said actuator is moved.

'7. In a device of the class described the combination including a pair of cooperating contacts, a cylindrical loosely fitting sleeve shorter than the combined length of said contacts and surrounding a portion thereof, and a resilient member having a movable end surrounding the base of one of said contacts and being supported at the other end, said member bearing against one end of said sleeve to seal the opening between the side of the sleeve and said contacts as said switch opens.

8. A switch comprising an elongated plate, a fixed contact carried by one end of Said plate, a resilient member supported at one end on said plate on the same side as said contact, the other end extending to a point beyond said contact, a cam cooperating with the extending end of said member, a, second resilient member spaced from the first mentioned member and carrying a second movable contact, cooperating with said first mentioned contact, an insulating sleeve surrounding said two contacts and serving to transmit motion from said first mentioned resilient member to the other resilient member to open the switch.

9. A switch comprising a movable contact and a xed contact, a sleeve open at each end enclosing said contacts, said sleeve being shorter than the combined length of said contacts, and an actuator surrounding the base of the fixed contact and movable with respect thereto, said actuator bearing against one end of the sleeve to seal the opening between the side of the sleeve and the xed contact when said switch is in the open position.

FRED C. SCHWANEKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 354,273 Thompson Dec. 14, 1886 1,253,210 Chubb Jan. 15, 1918 1,501,270 Chubb July 15, 1924 1,875,801 Bryce Sept. 6. 1932 2,230,428 Frank Feb. 4, 1941 2,262,386 Crabbs Nov. 11, 1941 2,293,701 Delmonte Aug. 25, 1942 2,339,676 Bucklen, Jr. Jan. 18, 1944: