US2747060A - Electric switches - Google Patents

Description

May 22, 1956 R. P. BALLoU 2,747,060

ELECTRIC SWITCHES Filed Sept. 26, 1950 2 Sheets-Sheet l f 27 E INVENToR.

May 22, 1956 R. P. BALLOU ELECTRIC SWITCHES 2 Sheets-Sheet 2 Filed Sept 26 1950 United States Patent ELECTRIC SWlTCl-IES Richard P. Ballon, Hartford, Conn., assigner to Federal Electric Products Company, Newark, N. l., a corporan tion Application September 26, 1950, Serial No. 186,357

9 Claims. (Cl. 20th-170) This invention relates to electric switches and more particularly to switches of the knife-blade type.

In the enclosed or safety type switch having a quick make and break mechanism, for example, and not by way of limitation, a mechanism as shown in the copending application of T. M. Cole and P. M. Christensen, Ser. No. 144,636, led February 17, 1950, and assigned to the assignee hereof, the switch action is elected by spring energy. This energy is produced by the preliminary motion of an external switch handle and serves to open the switch blade with a snap action. In the smaller switches, the complete movement of the switch blade may be effected by the spring energy, but in larger switches this energy is usually too large and it is customary to have the external switch handle first compress the spring and then break the engagement of the blade and the stationary contact by direct mechanical linkage, after which the spring snaps the blade to its full open position. However, on closing the switch, the spring must be strong enough to move the blade through its complete arc for lirm engagement with the stationary contact. As the handle throw is limited, and the spring energy must be produced in only a portion of the throw, in both the on and oi direction thereof, the force required to throw the handle may reach an excessive value unless the friction internally of the enclosure is kept low. In actual practice, such handle forces are high. However, if the energy required to move the switch blade through a substantial portion of its arc of movement can be materially reduced, less force is required to operate the handle and an easier operating switch will be produced. Since heating can occur at both the hinged and the rupture ends of the switch blade, adequate contact pressure must be provided at both ends. With the current the same at both ends of the blade, and since the hinge and rupture posts are similar conducting members, the contact pressure required at both ends of the blade is substantially equal. Therefore, when the blade is disengaged from the rupture post, the total friction operating on the blade is substantially cnt in half. However, a substantial torque is still required to move the blade to the full open position theretof. While some switches provide greater contact pressure at the rupture end of the blade, to minimize burning or oxidizing of the contacts, this does not reduce the contact pressure at the hinged end although it may change the ratio of said contact pressures.

Therefore, the primary object of the present invention is the provision of a switch which requires substantially less effort for handle operation than in the prior art.

Another object is the provision of a switch blade having adequate contact pressure at both the hinged and rupture ends thereof in the closed condition of the switch, the pressure at the hinged end being substantially reduced at the moment ot' disengagement of the rupture end, so that very little effort is then required to move the blade to the full off position thereof.

The above and other objects, features and advantages ice of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. 1 is a side view, s in elevation, illustrating a double-blade knife switch embodying the present invention, the switch being closed;

Fig. 2 is an end view, as seen from the arrow 2 in Fig. l;

Fig. 3 is a sectional View taken on line 3--3 of Fig. l;

Figs. 4, 5 and 6 are views similar to Fig. 3, with portions removed, showing modifications;

Fig. 7 is a fragmentary view similar to Fig. 3, showing another modication;

Fig. 8 is a View, in elevation, illustrating a singleblade knife switch embodying the present invention, the switch being closed;

Fig. 8A is a sectional view taken on the line SSA-8A of Fig. 8;

Fig. 9 is a sectional view taken on the line 9 9 of Fig. 8;

Fig. 10 is a front view of the switch of Fig. 8;

Fig. 11 is a view similar to Fig. l() showing a modification;

Fig. 12 is a fragmentary view, in elevation, illustrating another embodiment in a single-blade switch;

Fig. 13 is a sectional view taken on the line 13-13 of Fig. l2;

Figs. 14 and 15 are views similar to Fig. 13 illustrating modifications.

Referring now to Figs. 1, 2 and 3 in detail, there is shown a knife-blade switch 10 embodying, the present invention, comprising an insulation base 11, a stationary contact or rupture member 12 bevelled as at 13 and connected to a terminal member 14 and a movable blade-contact member 16 which is pivotally connected to the terminal stud or hinge contact 1S. The latter tapers in thickness as indicated at 19 (Fig. 3), for a purpose which will presently appear. The movable blade contact member 16 comprises the resilient metal strips 20 and 22 which are flared outwardly at the rupture ends thereof, as indicated at 24. Said blades are pivotally mounted on the stud 18 by a rivet 2S which is of greater longitudinal extent than the combined thicknesses of the blades and the stud so that the heads 27 of the rivet 25 are spaced from the adjacent blade surfaces, respectively, in the closed condition of the switch, as illustrated in Fig. 3. ln order to provide the required contact pressure at both ends of contact member 16, a bolt 26 extends through the aligned apertures 28, 28 in each of the strips 20 and 22, it being noted that the diameter of the bolt is smaller than the diameter of said openings to provide for relative movement of said strips and the bolt. A compression spring 3l) is mounted on the bolt, one end of said spring bearing against the outer surfaceof strip 2t) and the other end of said spring bearing against a nut 32 on the bolt. A lock-nut 34 is threaded on the end of the bolt, As a result of this construction, the strips 20, 22 of the blade-contact 1n may be adjusted to provide the required resilient contact pressure against thestationary contact 12 and the stud or hinge Contact 1S, The spring 3i) is characterized by a high spring constant sothat a small change in the compression thereof will cause a much larger change in the force exerted thereby. As here shown, an insulation operating member 36 is secured to strip 22, as with the rivets 38, for moving the blade-contact member 16 into and out of engagement with the companion stationary member 12. It will be understood that any other type of switch operating member can be used with the movable contact of the. present invention and that the switch operating member may be positioned above the movable contact member rather than below the movable contact member, as here shown. Although the present invention is applicable to various dilerent types of switches, it is intended primarily for use in a switch operated by a quick make and break operating mechanism such as, for example, that illustrated and described in the copending application of T. M. Cole and P. M. Christensen, Ser. No. 144,63 6, led Febmary 17, 1950, and assigned to the assignee hereof, said mechanism operating a bail which engages the operating member of the switch.

When the switch is opened, by moving the blade- Contact member 16 so as to disengage the flared portions 24 thereof from the stationary contact 12, the spring 30, which is compressed in the closed or circuit making condition of the switch, is free to expand immediately upon said disengagement. The expansion of the spring causes the strips 20 and 22 to collapse toward each other and, due to the high spring constant, a slight expansion only results in the dissipation of the spring energy whereupon the pressure between the pivoted ends of said strips and the stud 18 is relieved, said ends being permitted to move freely in the space between rivet heads 27 and the stud 18, bevelled edge 19 aiding this movement. Therefore, it will be apparent that any further rotary movement of the blade contact 16, after it disengages the stationary contact 12, to the full off position thereof may be achieved with very little friction at the pivoted end thereof. It will be noted that the bevel 13 at the free end of contact 12 permits it to be readily re-engaged by the flared ends of Contact 16 when the latter is moved to the closed position thereof.

In the modification illustrated in Fig. 4, the combination of the bolt 26 and the helical spring 30 is replaced by a rivet 40 which passes loosely through the aligned openings 28 in the strips 20 and 22 and with the flat strip spring member 42 which is engaged between one end of the rivet 40 and one of the blades of the movable contact, here shown as the blade 22. It will be noted that the spring 42 extends longitudinally of the movable contact member, one end of the spring being adjacent the flared end, for applying contact pressure when said end engages the stationary contact 12, and the other end of said spring being adjacent the pivoted end of the movable contact member for applying contact pressure at the stud 18. Spring 42 is also characterized by a high spring constant, said spring being tensioned in the closed condition of the switch. It will be understood that when the movable contact member 16 disengages the stationary contact 12, spring 42 will be effective to cause the blades thereof to collapse toward each other, in the same manner as helical spring 30, thereby relieving the contact pressure at the stud, as previously described, so that the movable contact member can be carried to the full olf position thereof with very little friction.

In the moditication illustrated in Fig. 5, the spring is completely dispensed with. In said modification the rivet 44 extends through the aligned openings 28 in each of the individual blades, said rivet having a loose t therein and the shank thereof being slightly shorter than the combined thickness of contact 12 and both blades, so that said blades are bowed inwardly when the switch is closed and thereby provide their own pressure on both the stationary contact 12 and the stud 18. The switch will operate substantially in the same manner as previously described so that when the blades disengage the stationary contact they collapse toward each other and the contact pressure is relieved at the pivoted end thereof.

In the modification illustrated in Fig. 6, a threaded bolt 46 and a nut 48 are used in place of the rivet 44 so that the switch can be adjusted to the desired pressure regardless of manufacturing variations. The switch so modified operates in the same manner as the switch of Fig. 5.

lt will be noted that in each of Figs. l through 6, the stud 18 is tapered at 19 on the edge portion thereof which confronts the stationary contact 12. As previously described, this serves to aid the collapse of the blades when they disengage the stationary contact 12. As shown in Fig. 7, in order to provide for the collapse of the blades with less clearance between the heads 27 of rivet 25 and the adjacent blade surfaces, the stud 18 is provided with an arcuate contour at the opposite sides 52, 53, thereof, and the adjacent ends of the blades are curved inwardly, as at 54, to conform to said contour.

Referring now to Figs. 8 through l5, the invention is embodied in a switch provided with a movable Contact member constituted by a single blade S6. In this connection, it will be noted that the stationary rupture-contact member 58 comprises the individual resilient contact elements 60 and 62 which are bowed toward each other, as at 64 to permit for the resilient engagement of the blade 56 therebetween. The distance between the bowed portions 64 is less than the thickness of blade 56 so that said portions are spread apart by blade 56 and in engaging the latter, apply the required spring contact pressure thereto. The blade is pivotally mounted between the spaced terminal members 66 and 68, which together comprise a hinge contact, the rivet 70 extending through said members and the blade for this purpose. For engagement with the blade, each of the members 66 and 68 is provided with an inturned flexible portion 72 which resiliently engages the blade 56 at both sides thereof in the closed condition of the switch, said inturned portions providing the required spring Contact pressure at the pivoted end of the blade. As illustrated in Fig. 9, portions 72 are normally disposed, as indicated in the broken line position and are flexed outwardly to the full line position by blade 56. Said portions 72 are so dimensioned that when the blade S6 is moved upwardly to disengage the stationary contact members 60 and 62, the blade is disengaged at approximately the same moment from the portions 72 and free to move axially of the rivet 70 so that the contact pressure is simultaneously relieved at both ends of the blade 56 and the blade may be then easily carried to its full off position with a minimum of friction. The pressure of the portions 72 against the blade 56 may result from the resilience of said portions 72 or spring means may be provided for pressing said portions against the blade.

In the modification illustrated in Fig. 1l, a single terminal member 74, which is similar to members 66 and 68, is used in place of said members. As here shown, the terminal member 74 is provided with the separate llexiblc portion 72, the blade 56 being pivotally mounted on member 74 by the rivet 76. In the closed condition of the switch, the inturned resilient portion 72 forces the blade 56 into rm engagement with one head 78 of rivet 76 to provide the required contact pressure. When the blade is disengaged from the stationary contact portions 64, as previously described, the blade is disengaged at approximately the same time from the inturned portion 72 and free to move axially of the rivet to relieve the contact pressure at the pivoted end thereof.

In the modification illustrated in Fig. 12, the blade 56 is secured on the hinge contact or terminal stud 80 by means of a threaded screw 82. The head of said screw is secured to the blade, in any suitable manner, as by welding at 83, and the shank thereof is threaded into the stud 80. In the closed condition of the switch, the blade 56 is positioned in abutment with the stud 80, as illustrated in Fig. 13. However, when the blade is rotated in a counter-clockwise direction for movement out of engagement with the stationary contact members 60 and 62, screw 82 simultaneously moves outwardly of the stud 80 thereby moving the blade out of abutment with the stud 80 to reduce the contact pressure at the pivoted end of the blade.

In the modification illustrated in Fig. 14, a nut 84 is secured to the stud 80 in any suitable manner, as by welding at 85. In this connection, it will be noted that the screw 82 has a loose tit in the stud but is Athreaded into the nut 84, to provide for easier assembly and adjustment of the various parts. This arrangement will operate in the same manner as the construction in Fig. 12.

In the modication illustrated in Fig. l5, the screw 82 has a loose lit in the stud and engages the threaded skirt 86 of a spring washer 88 which serves the same function as the nut 84. The use of the spring washer 88 permits the screw 82 to be attached to the blade 56 prior yto the assembly of the switch and, after the spring washer is tightened to the required degree with the blade in lthe closed position, said washer is then secured to the stud 80 in any suitable manner, such as by pinning or welding at 90. If desired, the washer may be provided with teeth which enter into the softer material of the stud 80 and thereby effect the securement thereof on the post without the necessity of welding or pinning.

It will be noted that in each of ythe above described embodiments, the movable contact member, upon its disengagement from the stationary contact, moves or is moved, along the axis of its pivot for relieving `the contact pressure at the pivoted end thereof.

Certain of the subject matter illustrated and described herein is claimed in my divisional application, Serial No. 546,365, tiled October 26, 1955, and assigned to the assignee hereof.

While I have shown and described the preferred embodiments of my invention, it will be understood that various changes may be made in the present invention without departing from the underlying idea or principles of the invention within the scope of the appended claims.

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

l. In an electric switch having a hinge contact, a stationary contact and a movable contact pivotally mounted on said hinge contact for releasable engagement with said stationary contact, the combination with said movable contact of means on said hinge contact for providing contact pressure between said movable contact and said hinge contact in the engaged condition of said movable contact, said means operating upon disengagement of said movable contact to relieve at least part of said contact pressure, said movable contact being movable laterally of said hinge contact, and said means being a resilient part on said hinge contact in yieldable contact engagement with a side surface of said movable contact only when the latter is engaged with said stationary contact, said stationary contact extending beyond said resilient part in the direction of pivotal movement of said movable contact to disengage said stationary contact, whereby significant friction is initiated in the closing movement of the movable contact when the movable contact iirst engages the resilient part at which point the movable contact is about to engage the stationary contact and significant friction is terminated in the opening movement of the movable contact when the movable contact disengages the resilient part.

2. In an electric switch having a hinge contact, a stationary contact and a movable contact pivotally mounted on said hinge contact for releasable engagement with said stationary contact, the combination with said movable contact of means on said hinge contact for providing contact pressure between said movable contact and said hinge contact in the engaged condition of said movable contact, said means operating upon disengagement of said movable contact to relieve at least part of said contact pressure, said movable contact being movable laterally of said hinge contact, and said means being spaced resilient portions on said hinge contact, the side surfaces of said movable contact being yieldably engaged between said resilient portions only when said movable contact is engaged with said stationary contact, said stationary contact extending beyond said resilient portions in the direction of pivotal movement of said movable contact to disengage said stationary contact, whereby signiiicant friction is initiated in the `closing movement of the movable contact when the movable contact first engages the resilient portions at which point `the movable contact is about to engage the stationary contact and significant friction is terminated in the opening movement of the movable contact when the movable contact disengages the resilient portions.

3. In an electric switch having a hinge contact, a stationary contact, a single blade movable contact, pivot means mounting said movable contact on said hinge contact for releasable engagement with said stationary contact, said movable contact being movable on said pivot laterally of said hinge contact, said hinge contact being provided with at least one resilient portion which is in yieldable contact engagement with a side surface of said movable contact only when the latter engages said stationary contact, said movable contact being disengaged from said portion for said lateral movement when disengaged from said stationary contact, said stationary contact extending beyond said resilient portion in the direction of pivotal movement of said movable contact to disengage said stationary contact, whereby significant friction is initiated in the closing movement of the movable contact when the movable contact first engages the resilient portion at which point the movable contact is about to engage the stationary contact and significant friction is terminated in the opening movement of the movable contact when the movable contact disengages the resilient portion.

4. An electric switch comprising a hinge contact, a rupture contact, and a movable switch member releasably engageable with said rupture contact, said switch member being mounted for movement on said hinge contact with a substantially loose lit therebetween in the open condi- `tion of the switch, and means on said hinge contact to provide for substantially tight engagement of the latter with said switch member when the switch is closed, said means being a resilient portion of said hinge contact which extends into the path of closing movement of the switch member, and yields outwardly during said closing movement, said rupture contact having resilient jaws between which said switch member has a substantially tight t, and said hinge contact means being dimensioned relative to said jaws in the direction of opening movement of the switch member for disengaging said switch member shortly after the release thereof by said jaws upon opening of the switch.

5. An electric switch comprising a hinge Contact, a rupture contact, and a movable switch member releasably engageable with said rupture contact, said hinge contact having spaced parts between which said switch member is pivotally mounted with a substantially loose iit in the open condition of the switch, and confronting resilient portions provided on said spaced parts, respectively, between which said switch member is substantially tightly engaged when the switch is closed, and said rupture contact extending beyond said spaced parts in the direction of opening movement of said switch member, whereby significant friction is terminated in the opening movement of the switch member when the switch member disengages the rupture contact at which point it is about to disengage the spaced parts.

6. An electric switch comprising a hinge contact, a rupture contact, and a movable switch member releasably engageable with said rupture contact, said hinge contact having spaced parts between which said switch member is pivotally mounted with a substantially loose lit in the open condition of the switch, and oppositely disposed, inwardly extending resilient portions provided on said spaced parts, respectively, and normally extending into the path of said switch member, whereby said resilient portions are spread outwardly by said switch member during its closing movement thus making yielding contact engagement with the side surfaces thereof, said rupture contact extending beyond said resilient portions in the direction of opening movement of said switch member, whereby significant friction is initiated in the closing movement of the switch member when the switch member iirst engages the resilient portions at which point the switch member is about to engage the rupture contact and significant friction is terminated in the opening movement of the switch member when the switch member disengages the resilient portions.

7. An electric switch comprising a hinge contact, a rupture contact, and a movable switch member releasably engageable with said rupture contact, said hinge contact having spaced parts between which said switch member is pivotally mounted with a substantially loose iit in the Open condition of the switch, and an inwardly extending resilient portion provided on one of said spaced parts normally extending into the path of said switch member, said resilient portion being operable to yieldingly press said switch member against the other of said spaced parts in the closed condition of said switch member, said spaced parts being dimensioned relative to said rupture contact, in the direction of movement of said switch member to disengage said rupture contact, whereby significant fric- -tion is initiated in the closing movement of the switch member when the switch member iirst engages the resilient portion at which point the switch member is about to engage the rupture contact and significant friction is terminated in the opening movement of the switch member when the switch member disengages the resilient portion.

8. An electric switch comprising a hinge contact, a rupture contact, and a movable switch member pivotally mounted on said hinge contact for releasable engagement with said rupture contact, each of said contacts having resilient means engaged by the switch member in the closed condition of the switch to provide contact pressure at both of said contacts, the hinge contact means being closer to the pivotal mounting of the switch member and shorter than the rupture contact means, whereby significant friction is initiated in the closing movement of the switch member only when the latter rst engages the hinge contact means at which point the switch member is about to engage the rupture contact means.

9. An electric switch comprising a hinge contact, a rupture contact, and a movable switch member pivotally mounted on said hinge contact for releasable engagement with said rupture contact, each of said contacts having resilient means engaged by the switch member in the closed condition of the switch to provide contact pressure at both of said contacts, the hinge contact means being closer to the pivotal mounting of the switch member and shorter than the rupture contact means, whereby signicant friction is initiated in the closing movement of the switch member only when the latter first engages the hinge contact means at which point the switch member is about to engage the rupture contact means, the resilient means on each of said hinge and rupture c011- tacts being constituted by spaced jaw members provided on each of said contacts, said jaw members extending into the path of movement of said switch member.

References Cited in the le of this patent UNITED STATES PATENTS 670,145 Bossert May 19, 1901 1,880,734 Boll et al. Oct. 4, 1932 2,063,954 Ramsey Dec. 15, 1936 2,186,476 Debby Ian. 9, 1940 2,278,057 Borza Mar. 31, 1942 FOREIGN PATENTS 16,762 Great Britain 1901 319,619 Germany Mar. 12, 1920

Images