US2981817A - Switch - Google Patents

Description

April 25, 1961 H. c. FRENTZEL SWITCH 3 Sheets-Sheet 1 Filed Aug. 20, 1958 INVENTOR Hagan/u GYM/M321 PM wmcw TTORNEYS Aprll 25, 1961 H. c. FRENTZEL 2,931,317

SWITCH Filed Aug. 20, less 5 Sheets-Sheet 2 V/ INVENTOR 4| 5 59 Hgymam 13M911 m r 7 Page, gwm Wm 27- 3 so I TTORNEYS April 25, 1961 H. c. FRENTZEL SWITCH 3 Sheets-Sheet 3 Filed Aug. 20, 1958 NEFINTOR mm 6', mad

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ATTORNEYS United States Patent O SWITCH Herman C. Frentzel, Milwaukee, Wis., assiguor, by mesne Filed Aug. 20, 1958, Ser. No. 756,095

Claims. (Cl. 200-170) This invention relates generally to electric switches and more particularly to apparatus for actuating electric switch contacts.

In operating electric switches, mechanical linkage positions the switch contacts so as to alternately open and close the electrical circuit. Some wear of the contacts is caused by mechanical interaction between the contact surfaces, however, the majority of wear is due to melting or vaporization of contact surfaces caused by the heating from instantaneous or prolonged arcing when the switch contacts are opened under load. In closing the switch contacts, rapid movement of the operated contact can result in heavy impact loads as well as contact bounce. The impact loads may damage the contacts and accelerate wear. Contact bounce induces arcing and is an undesirable circuit condition. A slower operating motion in order to eliminate these problems will cause other difficulties during the opening of the switch. A slow separation of contacts may induce severe and prolonged arcing which could greatly shorten contact life. In the closed condition, contacts must be held one against the other with sufficient force to insure a low resistance connection. With the stated switch construction and operating characteristics, it will be seen that a number of switch operating cycles will result in unsatisfactory contact spacing and closure conditions.

Accordingly, it is an object of the present invention to provide an electric switch which can be adjusted so as to provide the required contact spacing and contact closure force.

Another object of the invention is to provide an electric switch having actuating apparatus giving a required contact motion during operation and a selected contact force upon closure.

A further object of the invention is to provide an electric switch in which contact wear during switch operation will initiate corrective adjustments so as to restore normal contact spacing and closure force.

A still further object of the invention is to provide an electric switch in which wear of switch contacts will effect a visual indication or energize an alarm device so that the need for corrective action is made evident.

In one aspect, the electric switch of the invention includes a fixed contact and a moveable contact, the moveable contact actuating means being moved by an operating means connected thereto. An adjustable resilient coupling is used to interconnect the actuating means to the moveable contact. Movement of the actuating means by the operating means operates the contacts so that the moveable contact is moved into and out of engagement with the fixed contact. In this arrangement, the adjustable coupling will provide for wear and proper maintenance of contact closure force.

Other objects, advantages and features of the invention will become apparent from the following description and drawings which are merely exemplary.

In the drawings: 7

Fig. 1 is a from: elevational view of the electric switch 2,981,817 Patented Apr. 25, 1961 "ice of the present invention, illustrating the switch in one of its limiting positions under spring control.

Fig. 2 is a front elevatoinal view of the electric switch similar to Fig. l but illustrating the switch under control of a magnetic actuator in its other limiting condition.

Fig. 3 is a fragmentary side elevational view partially in section of the electric switch.

Fig. 4 is an enlarged fragmentary front elevational view of tne pointer and adjustable coupling.

Fig. 5 is an enlarged fragmentary front elevational view partially in section of the sensing switch arm and the adjustable coupling.

Fig. 6 is an enlarged fragmentary side elevational view of a modified form of adjustable coupling which may be used with the combination shown in Fig. 1 looking in the direction of the arrow in Fig. 1, showing the yoke member displaced and the ratchet engaged; parts being shown in section and other parts being broken away in the interests of clarity.

Fig. 7 is an enlarged plan view partially in section of ratchet mechanism for adjusting the coupling as shown in Fig. 6.

Fig. 8 is an enlarged fragmentary vertical sectional view of the ratchet mechanism similar to Fig. 6 but with the yoke member at rest and the ratchet disengaged.

Fig. 9 is an enlarged elevational view in the direction of arrows 9-9 on Fig. 7 showing the ratchet mechanism engaged.

Referring initially to Figs. 1, 2 and 3, a vacuum switch 10 is shown generally. The vacuum switch is provided with an evacuated glass envelope 11 and the vacuum envelope contains cylindrical contact elements comprising moveable contact 13 and fixed contact 14, the ends of which are contiguous when the switch is closed. *Inner shield 15 surrounds the ends of the contacts and electrical connection is made to the moveable contact by means of lead 16. The moveable contact 13 of vacuum switch 10 is operated with a linear motion by contact extension 17, moveable contact 13 being sealed with respect to the evacuated envelope 11 by a bellows element 18. Spring 19 urges contact rod 20 in a downward direction corresponding to the open possition of the vacuum switch contacts. The downward force of spring 19 is adjusted by pre-loading spring 19 through washer 21 and adjusting nut 22, which is threadably attached to rod 20.

Actuating means for the electric switch is coupled to rod 20 by means of the insulating link 23, insulatnig link 23 passing through a clearance hole in the supporting base 24. As shown in Fig. 3, pivot supports 25 are attached to supporting base 24, lever 26 being pivotally connected to supports 25 at its upper end and to actuating link 27 at itslower end. Operating means 28 may be a conventional electro-magnetic stroke motor which may be connected to actuating link 27 by a pivoted connection 29. Link 30 is connected to the levers of the other switches if the switches are ganged for a polyphase system. Restraining spring 31 attached at one end to the actuating link 27 urges the link 27 in the direction of the right side of the figures which is the open switch position. Energizing the operating means 28 will resuit in actuating link 27 being positioned to the left, as shown in Fig. 2, to the closed switch position. With operating means 28 deenergized, the force of spring 31 will return actuating link 27 to the right, as shown in Fig. 1.

As shown in Fig. 5, the lower end of insulating link 23 is provided with a threaded extension 32 on which adjustable coupling 33 is mounted. Coupling spring 34 is located within coupling 33 and cam 35 is attached to lever 26. Follower support 36 is mounted on stud 37 of extension 32 and carries follower 38. Spring 19 holds follower 38 against cam 35. Spring 34 establishes the contact pressure and provides for take-up as the contacts wear. The movement of spring 34 is limited by the washer at the lower end of stud 37. Follower support 36 is located by means of guide link 39 which is pivotally connected to the guide link support 40. Guide link 39 prevents rotation of the follower support 36 with respect to stud 37 and maintains substantial alignment of 01- lower support 36 with the vertical axis of the switch since the arcuate motion of guide link 39 is limited.

As shown in Fig. 1, spring 31 is holding the actuating linkage toward the right of the figure which corresponds to an open contact condition, cam 35 being in its most counter clockwise position and the follower 38 resting upon the lower dwell area 41 of the cam 35.

Upon energizing the operating means 28, the actuating linkage will be moved toward the left, as shown in Fig. 2, against the force of spring 31 and during such operation, lever 26 will be pivoted with respect to supports 25 in a clockwise direction. As shown in Figs. 4 and S, follower support 36 will be elevated by the rise portion 42 of cam 35 and then with the further linkage motion will come to rest upon the upper dwell area 43 of cam 35. This position, which corresponds to a closed circuit one, is also shown in Fig. 2. In the closed position, the insulating link has moved the moveable switch contact 13 into abutment with the fixed contact 14. The limited motion is the result of the follower moving up the rise portion 42 of cam 35. Because of the limited motion, guide link 39 maintains follower 36 in substantial alignment with a vertical axis, passing through the pivot of support 25.

The upward closing force is transmitted by the follower roller 38, follower 36, coupling spring 34, and thence to the coupling 33 which is threadably attached to extension 32. The height of the rise portion 42 of cam 35 is selected per the dictates of the required open circuit 7 contact gap. The shape of the rise portion is selected so as to establish a required velocity characteristic at the switch contacts for the existing velocity condition of the operating means 28. For example, the rise portion may be shaped so that a sinusoidal velocity condition will exist at the switch contacts upon opening and closing. Such a velocity condition will inherently have low final rates of change of displacement which in turn will minimize closure impact forces upon the switch contacts. The low initial rate of change of velocity will elfect reduced inertia forces on the linkage.

Initially, coupling 33 is adjusted so that the contacts come together just befort the end of the rise portion 42 of cam 35. The remaining upward motion which occurs before follower 38 enters the upper dwell area 43 of cam 35 serves to load one contact against the other through flexure of coupling spring 34. Without the coupling spring 34, a toggle action with excessive closure force on the contacts would result so that after a slight amount of wear all of the desired contact closure force would be eliminated.

After a period of operation of the switch, the contact gap will be increased due to mechanical wear and vaporization of the mating contact surfaces. This wear would lead to a condition wherein upon actuating the switch so as to close it, as shown in Fig. 2, the moveable contact would fail to touch the fixed one. This condition is corrected by adjustment of coupling 33 with respect to the threaded extension 32, thus rotating the coupling so that it moves away from insulating link 23 serving to elevate the link due to the reaction on coupling spring 34. Continued adjustmtnt of coupling 33 so as to elevate insulating link 23 after the switch contacts have abuttcd one another will cause loading of one contact upon another and flexure of coupling spring 34. Thus, it is seen, the adjustable coupling 33 permits the establishment of a preloading on the contact surfaces per the requirements of the vacuum switch and permits wear take-up for the settings.

To aid in adjustment of the coupling, index marks 44 and 45 may be applied to the periphery of the adjustable coupling 33, as shown in Fig. 4. Pointer 46 mounted on supporting base 24 would be set with respect to the index marks upon proper adjustment of coupling 33 and the index marks 44 and 45 spaced to indicate the vertical travel of adjustable coupling 33 in the closed switch position and corresponding to the satisfactory range of contact wear that would be permissible before further adjustment of coupling 33 is necessary. In this manner, a quick visual inspection of the pointer 46 with respect to the index marks 44 and 45 would inform the observer whether the coupling is satisfactorily adjusted to establish the proper contact closure force.

In Figs. 1 and 5, another means of indicating proper contact spacing is shown. With coupling 33 adjusted for the initial preload on the switch contacts, switch arm 47 of sensing switch 48 is positioned above the adjustable coupling 33 by means of tappet screw 49 which bears on button 50 of switch 48. The initial interval between coupling 33 and switch arm 47 is set to correspond to an acceptable range of wear of switch contact 13 and 14. Further switch wear beyond this limit would result in the adjustable coupling 33 rotating switch arm 47 about pivot 50 and thereby actuating the sensing switch 48. Switch 48 could in turn operate an indicator, an alarm device, or suitable control equipment to open the circuit to vacuum switch 10. Locking spring 51 is attached to insulating link 23 by means of nut 52, free end of spring 51 locking adjustable coupling 33 by engaging the teeth 53.

Referring to the drawings in Figs. 6 through 9, inclusive, means are shown for automatically maintaining the proper adjustment of the switch contact gap. Adjustable coupling 54, under the urging of resilient coupling spring 34, will rise with respect to supporting base 24 after a period of contact wear. In Fig. 6, a yoke 55 is pivotally mounted on the support base 56 attached to supporting base 24. Flat spring 57 urges the yoke 55 in a clockwise direction until it assumes its lower limit position as determined by stop screw 58, which is threadably mounted on support 24. Tappet screw 59 is positioned in yoke 55 so that the initial clearance between coupling 33 and the end of the tappet screw 59 corresponds to the range of acceptable wear of the switch contacts 13 and 14. The periphery of adjustable coupling 54 is provided with ratchet teeth 60. Ratchet arm 61 is fixedly mounted on pawl 62, which is pivotally mounted to bracket 63. Bracket 63 is fixedly attached to lever 26 so that the pawl 62 and the ratchet arm assembly are carried along by the lever 26 during actuation of the switch linkage.

As shown in Fig. 6, wear of the contact surfaces has progressed until the adjustable coupling 54 has contacted the end of tappet screw 59 so as to rotate yoke 55 in a counter-clockwise direction. The motion of yoke 55 serves to move resilient arm 64 in a vertical plane until it overlaps the pawl 62. As shown in Figs. 6 and 9, with lever 26 in a position corresponding to a closed contact condition, the resilient arm 64 will come in contact with pawl 62. As shown in Fig. 6, pawl 62 is normally p0- sitioned by fiat spring 65 so that the ratchet arm 61 is maintained disengaged from the ratchet teeth 60. Contact of the resilient arm 64 with pawl 62 serves to rotate the pawl against spring 65 so as to engage ratchet arm 61 with ratchet teeth 60.

Subsequent deenergizing of the operating means 28 so as to permit opening of the vacuum switch 10 will result in lever 26, as shown in Fig. 9, moving in a counterclockwise direction. This motion is seen as an upward displacement of lever 26 in Fig. 7. Consequently, the ratchet arm 61 will move in an upward manneras viewed in Fig. 7, thereby rotating coupling 54 in a counterclockwise direction. The left-hand thread of extension 32 and coupling 54 will cause the coupling to move downward with such ratchet motion, as viewed in Fig. 8. Under the urging of flat spring 57, yoke 55 and its tappet screw screw and yoke following the adjustment cycle. of the left-hand thread is sufiicient that a clearance will mascot? 59 will follow the downward motion of coupling 54 thereby eflecting a clockwise rotation of the yoke. This will serve to position resilient arm 64 so that it no longer overlaps pawl 62 and it thereby assumes the position shown in Fig. 8. Stop screw 58 serves to limit the downward motion of tappet screw 59 in yoke 55 so that it is not necessary for adjustable coupling 54 to support the The pitch be established between adjustable coupling 54 and tappet screw 59 with one or more ratchet motions.

It should be understood that variations may be made in the details of the construction without departing from the spirit of invention, except as defined in the appended claims.

What is claimed is: 111. An electric switch including fixed contact means,

moveable contact means, actuating means, operating means, a resilient coupling, said coupling interconnecting said actuating means with said moveable contact means,

the movement of said actuating means by said operating means being transmitted through said resilient coupling to operate said contact means so that said moveable contact means is alternately contiguous with said fixed contact means, and indicating means associated with said coupling to show required location of said coupling and said moveable contact means for maintaining desired closed contact conditions and for aiding in adjustment of said moveable contact.

2. An electric switch including a fixed contact, a moveable contact, actuating means, operating means, a resilient coupling interconnecting said actuating means with said movable contact, said resilient coupling transmitting the movement of said actuating means in response to said operating means to said moveable contact means to move said moveable contact relative to said fixed contact, secondary switch means actuated by said coupling upon a predetermined displacement of said coupling from its normal position during closed contact conditions, and alarm means connected to said switch means and energized thereby, so as to indicate a change from normal closed contact conditions.

3. An electric switch including a fixed contact, a moveable contact actuating means, operating means, a resilient coupling interconnecting said actuating means with said moveable contact, said resilient coupling transmitting the movement of said actuating means in response to said operating means to said moveable contact to move said moveable contact relative to said fixed contact, secondary switch means, alarm means energized by said secondary switch means, and follower means for actuating said secondary switch means, said follower means being in contact with said coupling, whereby displacement of said coupling from its normal range of positions during closed contact conditions moves said follower means to actuate said secondary switch means and to energize said alarm means.

4. An electric switch including a supporting base, a fixed contact attached to said base, a moveable contact, an actuating link attached to said moveable contact, a force means urging said link in a direction to open said contacts, a guide member to limit said link to a substantially linear motion, a lever pivotally connected to said base, a cam attached to said lever, said cam having surfaces providing dwell for open and closed contact states and a selected motion for transient contact states, a cam follower, a coupling connected to said link, a resilient connection between said coupling and follower, and an operating means connected to said lever, said operating means positioning said lever and said cam so as to open and close said contacts, said coupling and said resilient connection providing adjustment to maintain required closure force between said contacts.

5. An electric switch including a supporting base, a fixed contact mounted on said base, a moveable contact,

an actuating link attached to said moveable contact, a

force means urging said link in a direction to open said contacts, a guide member to limit said link to a substantially linear motion, a lever pivotally connected to said base, a cam attached to said lever, a cam follower, a coupling connected to said link, a resilient connection between said coupling and follower, an operating means connected to said lever alternately to open and to close said contacts, clutching means pivotally mounted on said link and normally disengaged from said coupling, supporting means pivotally mounted with respect to said base and positioned by said coupling, follower means attached to said supporting means, said follower means upon sufiicient displacement of said pivoted supporting means in response to change from the normal position of said coupling due to wear of said contacts operating to move said clutching means while in the closed position of said switch thereby engaging said coupling, such that upon the opening motion of said contacts, said clutching means will rotate said coupling, thereby positioning said moveable contact toward its normal closed contact position.

6. An electric switch including a supporting base of insulating material, a fixed contact mounted on said base, a moveable contact, an actuating link of insulating material attached to said moveable contact, a force means urging said link in a direction to open said contacts, a guide member to limit said link to a substantially linear motion, a lever pivotally connected to said base, a cam attached to said lever, a cam follower, a coupling connected to said link, a resilient connection between said coupling and follower, an operating means connected to said lever, said means positioning said lever and said cam to alternately open and close said contacts, ratchet teeth on the periphery of said coupling, a ratchet arm pivotally mounted on said lever and normally disengaged from said teeth, supporting means pivotally mounted with respect to said base and positioned by said coupling, a resilient arm attached to said supporting means, said arm upon sufiicient displacement of said pivoted supporting means in response to change from the normal position of said coupling due to wear of said contacts, moving said ratchet arm, while in the closed position of said switch thereby engaging said ratchet teeth, such that upon the opening motion of said contacts, said engaged ratchet arm will rotate said coupling, thereby positioning said moveable contact toward its normal closed contact position.

7. In a reciprocable switch contact actuating means, the combination including supporting frame means, cam means mounted to swing with respect to said frame means, said cam means having surfaces providing dwell for opened and closed contact states and a selected motion for transient contact states, reciprocable switch contact means, fixed switch contact means, actuating means connected to said reciprocable contact means, cam follower means on said actuating means, and operating means connected to said cam means, said operating means being reciprocable to swing said cam means so as to move said reciprocable contact means into and out of operative engagement with said fixed contact means.

8. In a reciprocable switch contact actuating means, the combination including supporting frame means, cam means mounted to swing with respect to said frame means, said cam means having surfaces providing dwell for opened and closed contact states and a selected motion for transient contact states, reciprocable switch contact means, fixed switch contact means, actuating means connected to said contact means, cam follower means on said actuating means, a resilient adjustable coupling connecting said follower means to said actuating means, and operating means swinging said cam means to move said reciprocable contact into and out of operative engagement with said fixed contact means, said adjustable resilient coupling providing compensation for wear and maintenance of contact closure forces.

9. In a reciprocable switch contact actuating means, the

combination including supporting frame means, cam means pivotally mounted on said frame means, reciprocable switch contact means, actuating means connected to said contact means, cam follower means, an adjustable resilient coupling connecting said follower means to said actuating means, an operating means moving said contact into and out of operative engagement with a fixed contact, clutching means pivotally mounted on said cam means and normally disengaged from said coupling, sup

' porting means pivotally mounted with respect to said frame means and positioned by said coupling, and other follower means attached to said supporting means, said other follower means upon suflicient displacement of said pivoted supporting means in response to change from the normal position of said coupling due to wear of said contacts, operating to move said clutching means while in the closed contact position thereby engaging said coupling, such that upon the opening motion of said contacts, said clutching means will displace said adjustable coupling thereby positioning said reciprocable switch contact toward its normal closed position.

10. An electric switch including a fixed contact, a moveable contact, actuating means, operating means, a resilient coupling interconnecting said actuating means with said moveable contact for moving said moveable contact relative to said fixed contact in response to movement of said actuating means by said operating means so that said moveable contact is alternately contiguous with said fixed contact, indicator means, and scale means on said coupling and cooperating with said indicator means to indicate normal range of location of said coupling and said moveable contact, so as to maintain satisfactory closed contact conditions and to aid in adjustment of said moveable contact.

References Cited in the file of this patent UNITED STATES PATENTS

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