US2631205A

US2631205A - Snap action mechanism

Info

Publication number: US2631205A
Application number: US78755A
Authority: US
Inventors: Millard Harper
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1949-02-28
Filing date: 1949-02-28
Publication date: 1953-03-10
Anticipated expiration: 1970-03-10

Description

engage the contacts I5 in the other position of each spring system I I. The Xed contacts I3 and I5 and the mobile contacts I2 may be connected to external circuits through the

mounting screws

21, 3I and 26 and conventional terminals 3i), 35 and positioned in recesses formed on the bottom of the base I5 and in electrical conductive relation respectively with the mounting screws.

Insulating barriers

32 and 33, respectively, projecting upwardly from the base I5, at opposite ends of the spring systems I I separate the spring systems to minimize arcing between the respective contacts. l

In this embodiment of the Iinvention the driving spring system IE is mounted on the base I5 to overlie the spring systems II. In general the spring system I5 includes spaced compression members 35 and a tension member 35. At one end the compression members 3 are received in transversely extending grooves 3l' (see Fig. 3) formed on depending fingers 38 of a rigid bracket 3B. 'Ihe latter bracket is secured on a shoulder l formed on the base I5, adjacent the free endsI 22 of the spring systems l I, in a cantilever fashion and in-general overlies the spring systems I I and I6. At their opposite ends the compression members 34 are interconnected by a crosspiece 52 (see Fig. 2) disposed between the base I5 and the bracket 39 and forming a portion movable between preselected positions. At one end the tension member 36, which in this instance is in the form of a coil spring, has an end looped over an ear 43 projecting upwardly from the crosspiece 52 to provide a pivotal mounting 53d. The opposite end oi the tension member 36 is looped over an arm or a depending end 45 of the lever I1 to provide a pivotal mounting at 55a, the bracket 39 being formed with a slot 45a at its outer end (see Figure 1) to permit this connection and movement of the lever I1 to be herein after described. The lever I1 as shown, overlies and is pivotally mounted on the bracket 39 so that movement of the lever about its pivotal mounting moves the end of the tension member 35 mounted on the lever I7 relative to the pivotal v recesses 31 of the compression members 35 to actuate the driving snap spring system I3. To eiect the pivotal mounting of lever I1 in this embodiment of the invention, the lever I1 is formed with depending leg portions 45 spacing y the lever I1v above the bracket 39 and having ren cesses 51 shaped to receive knife edges i8 formed by bending tabs 49 downwardly along opposite sides of the slot 45a. Movement of the end I5 ci the lever I'I supporting the tension member 35 is limited in one direction by engagement of the lever I1 with the upper surface of the insulating barrier 33. Movement of the lever I1 in the opposite direction is limited by engagement of the operating arm or free end 35 of the lever I1 with the bracket 39.

Another phase of the invention is concerned with novel means for interconnecting the driving spring system I6 with the driven spring systems II. As best shown in Figs. 4 and 5 the connection comprises an inverted U-shaped member 5I having a bridging portion 50 rigidly attached to the crosspiece 52 as by a rivet and having the ends of its leg portions 53 engageable with the upper sides of the free ends 22 of the spring systems II, and an inverted T-shaped member 55 having its stem portion 5B pivotally mounted on the crosspiece 42 and its laterally extending arms 51 engageable with the opposite sides of the free ends 22 of the spring systems II. When the leg portions 53 engage the free ends 22 of the driven spring systems II the arms 51 are spaced from the free ends. Similarly when the arms 5i' engage the free ends 22 the legs 53 are spaced from the free ends 22. 'Ihis construction thus provides a lost motion connection between the driving spring IB and the driven springs I I. The legs 53 in eiiect form'ri'gid anvils orhammers for striking the free ends 22 for simultaneously disengaging the mobile contacts I2 from engagement with the contacts I5 with a hammerblow. The pivotal connection of the T-shaped member 55 insures that a uniform pressure is applied to both contactsV I2 when the arms 51 engage the free ends 22.

Another aspect of the invention is concerned with minimizing the bounce of the contacts I2 when they initially engage either of the spaced contacts I3 or the spaced contacts Iii. In this embodiment of the invention this is effected by a slug 58 being disposed in the coil spring 35. As best shown in Figs. 2 and 3'the slug comprises a cylindrical portion 59 and a head portion 5S. The cylindrical portion has a diameter that is approximately two to three thousandths inches smaller than the inside diameter of the' coil spring. The head portion 3l has a diameter larger than the internal diameter of the coil spring 35 so as to position the slug and prevent movement of the slug into the interior o1" the coil spring. The slug 53 may be formed from copper or other suitable material. With a switch construction of the above character it has been found that the tendency of the mobile contacts to bounce or chatter is substantially, if not entirely eliminated.

The operation of the foregoing switch construction may be readily understood with the following description with reference to Figs. 2-5. In Figs. 2 and 4 the spring systems II and I6 are in their normal position and the mobile contacts I2 engage the iixed contacts I3. The lever I1 is biased by the tension coil spring 36 so that the end 45 of the lever I1 supporting the tension member 35 is urged into engagement with the top of the barrier 33. The 'leg portions 53 of the inverted U-shaped insulating member 5I engage the free ends 22 of the spring systems II and augment the force of the latter tending to cause the mobile contacts i2 to be forced against the contacts I3 with a positive pressure. To actuate the switch a force is ap-V plied to the free end 35 of the lever I1 so that the lever I1 is moved in a counterclockwise direction as seen in Fig. 2 about its pivotal support determined by the depending legs 56 of the lever and the knife edges 48. Counterclockwise movement of the lever I1 moves the connection between the lever I1 and the tension member 35 relative to the pivotal support ofthe compression members 34 (recesses 31 on the depending arms 38) so that the spring system i6 is moved through its axis of unstable equilibrium or moves overcenter. As soon as the spring system I5 goes overcenter the crosspiece 42 moves between its preselected positions with a snap action. As a consequence the arms 51 of the inverted T- shaped member` 54 move, with preliminary lost motion, into engagement with the underside of the free ends 22 of the spring systems II; The arms 51 in eifect'form anvils which strike the movable free ends 22 so that movement of the mobile contacts I2 away from iixed'contacts I3 is initiated by a hammerblow action. When the contacts I2 engage the contacts` Ill the arms 51 of the inverted .T-*shaped' member 5I! urge member movable between preselected positions interconnected at one end with said rst stressed member and formingan end free to move between preselected positions with a snap action, means for mounting the opposite end of the first stressed member, a lever having a iirst end and a seco-nd end, means mounted on said base acting on an intermediate portion of said lever to provide a pivotal mounting for the lever about which the second end is movable to move the first end, said rst end of the lever supporting the opposite end of the second stressed member to define with said rst stressed member a spring system and m-ovable to move the centerline of the second stressed member past the mounting means for the first stressed member to actuate the spring system, one of said stressed members being a coil spring, and a slug mounted in said coil spring comprisinga headed portion and a cylindrical portion, said cylindrical portion being or substantially the same diameter as theinside diameter of the coil spring and disposed therein and said headed portion abutting against an end of the coil spring'to prevent axial movement of the slug into the coil, said slug coacting with said coil spring to minimize bounce and chatter of the free end of the independent spring system asY it moves into its respective rest positions.

5. In a snap action device of the type having at least one independent spring system supported on a base and having an end free to move into preselected rest positions with a snap action, the combination of a rst stressed member, a second stressed member interconnected at one end with said first stressed member and forming an end free to move between preselected positions with snap action, one of said stressed members being formed as a coil spring, an'elongated mass extending interiorly of said coil spring lengthwise thereof to be supported thereby for minimizing bounce and chatter of the free end of the independent spring system as it moves into its respective rest positions, a bracket mounted on said base to overlie said free end of the stressed members, said bracket being formed with means for xedly pivotally mounting the opposite end of the iirst stressed member, a lever formed at one end with a rst depending arm intercon-A nected with the opposite end of the second stressed member to support the same, said lever also being formed with a second depending arm intermediate its ends coacting with said bracket to pivotally m-ount the lever thereon, pivotal movement of the lever effecting displacement of said first depending lever arm to move said opposite end of the second stressed member past said opposite end of the first stressed member to effect snap action movement of the free end of the driving spring system, and spaced abutment means mounted on said free end of the driving spring system and engageable with the free end of'said independent spring system in at least one of its rest positions for urging the free end into said rest positions and movable relative to said free end of said independent spring system upon snap movement of said free end of the-driving spring system to initiate movement of the free end of said independent spring system with a hammerblow snap action.

6. In a snap action device of the type having `a pair of independent spring systems supported on a base and each having an end free to move into preselected rest positions `with snap action, the combination of a rst stressed member, a second stressed member interconnected at one end with said rst stressed member and forming an end free to move between preselected positions with snap action, a bracket mounted on said base to overlie said free end of the stressed members, said bracket being formed with means for xedly pivotally mounting the opposite end of the first stressed member, said bracket defining a pivotal knife edge spaced from said mounting for the opposite end of the rst stressed member, a lever formed at one end with a rst depending arm interconnected with the opposite end of the second stressed member to support the same; Vsaid lever also being formed with a second depending arm intermediate its ends formed with' a pivotal recess receiving said knife edge on said bracket to pivotally mount the lever thereon, pivotal movement of the lever effecting displacement of said first depending lever arm to move said opposite end of the second stressed member past said opposite end oi the iirst stressed member to effect snap action movement of the free end of the driving spring system, pivotally mounted abutment means mounted on said free end of the driving spring system and engageablewith one side of the ree ends of said independent snap springs in one of their rest positions, and abutment means rigidly mounted on the free end loi" the driving spring system in spaced relation to the pivotally mounted abutment means and engageable with the free ends of the independent spring systems on the side thereof away from that engaged by the pivotally mounted abutment means in the other rest position of said free ends of the independent spring systems, said rigidly and pivotally mounted abutment means forming a lost motion connection between the driving and independent spring systems, said rigidly mounted abutment means effecting simultaneous movement of the free ends of the independent spring systems from said one rest position with a hammerblow snap action upon actuation of the driving spring system.

HARPER. MILLARD.

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

UNITED STATES PATENTS Number Name Date 1,000,052 Thordarson Aug. 8, 1911 1,909,037 Armstrong May 16, 1933 1,910,510 Warner May 23, 1933 1,924,639 Corcoran Aug. 29, 1933 Y1,995,620 Monroe Mar. 26, 1935 2,277,111 Johnson Mar. 24, 1942 2,486,061 Ransome ct. 25, 1949 2,487,374 Riche et al Nov. 8, 1949 FOREIGN PATENTS Number Country Date 148,964 Great Britain Sept. 15, 1921