US2582834A - Snap switch - Google Patents

Description

Jan. 1 5, 1952 M. F; KAUTz 2,582,834

SNAP SWITCH Filed Dec. 31, 1949 2 SHEETS-SHEET l INVENTOR. MURRELL E KAUTZ Jan. 15, 1952 M. F. KAUTZ SNAP SWITCH Filed DSG. 31, 1949 2 SHEETS--SHEET 2 il llllzllemwlll INVENTOR. MURRE LL F.' KAUTZ Patented Jan. l5, 1952 SNAP SWITCH Murrell F. Kants, Minneapolis, Minn., aaalgnor to Minneapolis-Honeywell Regulator Company. Minneapolis, Minn.. a corporation of Delaware Application December 31, 1949, Serial No. 136.351

Sclaima. l

This invention relates to precision snap switches in which the actuating forces are relatively small and must be held within prescribed limits. More particularly the invention relates to a self return magnet snap switch of relatively high current handling capacity.

In order to manufacture precision snap switches in quantity at low cost it is essential that the various parts may be made to tolerances that readily can be achieved by mass production techniques. Design of the switch must be such that the required accuracy is achieved by adjustments made after assembly.

An object of the invention is to provide a switch structure that is easily adjustable to obtain desired operating characteristics.

A further object is to provide an easily adjustable snap switch employing a permanent magnet that produces snap action and also aids in extinguishing the arc between the contacts as they are separated, the structure being such that the ruptured arc may be of either polarity with respect to the two contacts.

Another object is to provide a switch structure having a novel arrangement for adjusting the minimum clearance between the armature and magnet. i

Another object is to provide a novel arrangement for correlating the positions of the pole faces of the permanent magnet and the armature surface presented thereto for assuring proper utilization of the magnetic characteristics of the permanent magnet.

Other objects will be evident from the following written description and claims, and from the drawing in which Figure 1 is an elevation, partly in section, of a push button actuated magnet snap switch,

Figure 2 is a fragmentary plan of a portion of the switch,

Figure 3 is a fragmentary elevation. partly ln section, as seen from the left of Figure 1, and

Figures 4, 5 and 6 show successive steps leading up to the final adjustment of the switch as shown in Figure 1.

In the illustrative embodiment of the invention the switch mechanism is mounted on a base I0 and is enclosed by a. cover Il. Both the base and cover are formed of suitable dielectric material such as molded Bakelite. The cover is held on the base by a pair of spring clips l2 that engage suitably shaped recesses in the base and cover. The base is provided with openings I4 adapted to facilitate mounting the switch for actuation by other mechanism.

A pivot bracket I6 is secured to the base I0 by a pair of screws I1, only one of which is shown in the drawing. The screws Il also serve to attach a terminal I3 to the base and to conduct electricity between the bracket IB and terminal Il. The bracket I6 has a pair of upstanding oblique portions Isa that are notched as shown in Figure 2 to provide a knife edge pivot for a switch arm 20.

The switch arm comprises a lower portion 22 having laterally extending ears 22a disposed Y at an angle with respect to the switch arm and notched as shown in Figure 2 to provide a knife edge pivot engaging the pivot bracket portion lia. The pivotal axis for the switch arm 20 is determined by the knife edge engagement of the bracket portions I6a with the lower flat surfaces of the portions 22a of the switch arm. The switch arm is maintained on this axis by engagement of the knife edges of the arm portion 22a with the upper flat surfaces of the bracket portions I6a. This pivot structure is covered by the application of Willis H. Gille, Serial No. 136,383, filed on even date herewith.

The lower portion 22 of the switch arm 20 is extended to the left to form an armature 24 that cooperates with a U-shaped permanent magnet 25 disposed in a recess in the base I0. As is shown most clearly in Figure 2 the armature 24 has a circular opening therein that is substantially concentric with the switch contacts as will appear hereinafter. The switch arm 20 has an over arm 26 secured to the portion 22 by rivets 2l. A flexible contact blade 29 is riveted to the right hand end of the over arm 26 and carries a movable contact adjacent its left hand end. The left hand end of the blade 29 is bent upwardly beyond the contact 30 and is provided with an opening 32, as seen in Figure 3, through which the left hand end of the overarm 26 extends. The opening 32 is shaped to provide a limited amount of movement between the blade 29 and the arm 26. The right hand end of the arm 2i which carries the blade 29 may be bent with respect to switch arm to select the desired pressback force or, in other words. the force with which the contact 30 is biased away from the overarm 26. In this manner the minimum contact pressure existing under non-transitory conditions may be established.

A stationary contact 34 is carried by a bracket 35 which is secured to the base I0 by a pair of screws 36 that also secure a terminal 31 in place on the base I0 and provide an electrical path between the stationary contact 34 and the terminal 31. A low resistance electrical path between the pivot bracket I6 and the movable contact I3 is provided by a pigtail connection 88 that may be spot welded to the bracket I8 and to the switch blade 29 adjacent the movable contact.

A curved leaf spring 4Il best seen in Figure 3, engages the underside of the contact bracket 35 at its ends, and at its center engages a block 42 which overlies a strip 43 of insulating material that lies within the central portion of the U-shaped permanent magnet 25. The spring 4l biases the magnet 25 into engagement with the base l and with a screw 45 that is adapted to adjust the position of the right hand pole of the magnet 25 as will appear hereinafter.

'I'he switch arm 20 is actuated in a clockwise direction and against the bias of the magnet 25 acting on armature 24 by a push button 41 that is slidably carried in the upper portion of the cover Il. 'I'he push button 41 engages a leaf spring 48 which is secured at its left hand end to a lever 48. The lever 49 is pivotally carried in a bracket 50 secured to the base I0. A compression link 52 interconnects the right hand end of the lever 49 and the right hand end of the switch arm 20. It will be understood that as the push button 41 is depressed, energy is stored in the blade 48 until sufficient force is available to rotate the switch arm 20 in a clockwise direction against the pull of the permanent magnet 25. Likewise, the blade 48 is sufficiently resilient so that suillcient force will be available throughout the movement of the switch arm to continue such movement throughout the possible range o'i' movement thereof. The bracket 50 is provided with a portion I that engages the left hand end of the switch arm portion 28 to limit clockwise movement thereof. The bracket portion 5l is bendable with respect to the bracket 50 to determine the maximum separation of the contacts. The contacts will reclose when the button 41 is raised to a point where magnetic attraction overcomes the force of the blade 48.

As stated above, the invention contemplates adjusting means to enable very accurate switch operation while permitting the various parts thereof to be made by mass production manufacturing techniques. To secure desired switch operation the clearance between the armature 24 and each of the poles of the magnet 25 in switch closed position may be in the order of three thousandths of an inch. On the other hand, the manufacturing tolerance of some parts of the switch may be as high as thousandths of an inch. This accuracy of spacing between the magnet poles and the armature is necessary in order to obtain the desired operating characteristics. These characteristics are: the force that must be applied to the push button 41 in order to snap the switch to open circuit position, the force at the push button 41 at which the switch will return to closed circuit position, and travel of the push button 41 between these two positions.

Figures 4, 5 and 6 together with Figure i illustrate the procedure in adjusting the switch. As the parts are manufactured, the armature 24 is disposed at an angle of approximately 5 degrees with respect to the arm portions 22 and 28. The switch arm portion 22 is weakened by a cutout portion 55, as seen in Figure 2, so that angular displacement of the armature 24 with respect to the remainder of the switch arm will take place largely at a point well removed from the portions of the armature 24 that cooperate with the magnet 25. A screw 51 extends between the over arm 28 and the armature 24 to adjust the angular relation between the armature 24 and the remainder of the switch arm 28. When the switch arm is initially assembled on the base I0 and is pivotally mounted on bracket I6, the armature 24 will engage the remote pole of the magnet 25 as shown in Figure 4. The screw 51 is adjusted to remove most of the angle between the armature 24 and the remainder of the switch arm 20. By this adjustment the movable contact 30 is brought into engagement with stationary contact 34 as shown in Figure 5. However, the inner pole of the magnet 25 is still out of engagement with the armature since the recess in the base I0 which receives the magnet 25 is so shaped that for any possible variation in dimensions of the parts the inner pole is always lower than required. In order to properly correlate the position of the magnet poles with respect to the v`armature, the screw 45 is adjusted in the base I0 to bring the inner magnet pole into engagement with the armature 24 as shown in Figure 6. All the foregoing adjustments may be made without the actuating lever 49 and spring blade 48 being in place on the switch.

In actual practice the foregoing adjustments may be made by placing a source of electricity and a pilot lamp in series with the switch contacts. Screw 51 is a usted, starting from the position shown in Figure 4, until the pilot lamp is lighted. This will place the parts in the position shown in Figure 5. The screw 45 is then adjusted until the lamp goes out. which will bring the parts to the position shown in Figure 6 but with the contacts separated by a very small amount.

In order to obtain the required effort at the push button in order to open the contacts, the screw 51 is then adjusted to raise the armature from the magnet poles a distance sufllcient so that the magnetic pull on the armature is the proper value. This may be determined by measuring the force that must be applied to blade 48 to actuate the switch arm to open contact position. The parts will then be in the position shown in Figure 1.

In order to adjust the return effort, the switch is actuated to open contact position and the force applied to the blade 48 reduced until the switch arm snaps counterclockwise to closed circuit position. This force may be adjusted by bending the bracket portion 5I to determine the separation of the armature from the magnet at open circuit position. The amount of travel of the push button 41 between open and closed circuit position is determined by the spring rate of the blade 48 together with the actuating forces. Since the rate of the blade is selected to assure positive snap action with the chosen magnetic characteristics and the pressback force the blade 28, the button travel will also depend on the actuating forces as adjusted in accordance with the procedure outlined above.

It will be noted that the contacts lie between the poles of the magnet and therefore when circuit is broken by opening contacts the magnetic field extending across the contacts will serve to blow the arc toward one side of the switch as determined by the polarity of the arc. Since the switch is symmetrical on the two sides it is immaterial in which direction the arc is blown.

- assasss Thus, the switch may be used to control relatively heavy alternating current or to control direct current without regard to polarity.

It will be apparent that a switch has been provided that may be accurately adiusted to have the required characteristics and that may be manufactured economically by use of ordinary manufcaturing techniques. While only one embodiment of the invention has been shown it will be apparent that the various features of novelty may be employed in many modifications of the disclosed switch. The scope of the invention is to be limited only by the appended claims.

I claim as my invention:

1. In a snap switch, a base, a stationary contact on said base, a permanent magnet pivotally mounted on said base with opposite poles disposed on opposite sides of said stationary contact, the pivotal axis of said magnet being so located that movement of said magnet raises or lowers only one of the poles with respect to the operative surface of said stationary contact, means for adjusting the angular position of said magnet on said base, an arm pivotally mounted on said base on an axis parallel tothe pivotal axis of said magnet in said base. a movable contact on said arm adapted to cooperate with said stationary contact, an varmature pivotally mounted on said arm on an axis parallel to the pivotal axis of said arm, and means for adjusting the angular relationship between said arm and said armature to adjust the relative posi- Vtions of said armature and said movable contact and therefore the spacing between said amature and said magnet when said contacts are in engagement.

2. In a snap switch, a base, a stationary contact on said base, a permanent magnet pivotally mounted on said base with opposite poles disposed on opposite sides of said stationary contact, the pivotal axis of said magnet being so located that movement of said magnet raises or lowers only one of the poles with respect to the operative surface of said stationary contact, means for adjusting the angular position of said magnet on said base, an arm pivotally mounted on said base on an axis parallel to the pivotalv armature and said magnet when said contacts are in engagement.

3. In a snap switch, a base, a stationary contact on said base, a switch arm pivotally carried on said base, a movable contact on said arm adapted in one position of said arm to engage said stationary contact, a permanent magnet pivotally mounted on said base on an axis paralle'i to the pivotal axis of said switch arm and having its poles disposed on opposite sides of said stationary contact, the pivotal axis of said magnet being so located that pivotal movement of said magnet raises or lowers only one of the poles with respect to the operative surface of said stationary contact, means for adjusting the angular position of said magnet on said base, and an armature on said switch arm cooperating with said magnet.

4. In a snap switch, a base, a stationary contact on said base, a switch arm pivotally carried on said base, a movable Contact on said switch arm, an armature on said switch arm, means for adjusting the position of said armature with respect to said base when said contacts are in engagement, a permanent v magnet pivotally mounted on said base on an axis parallel to the pivotal axis of said switch arm and having its poles disposed on opposite sides of said stationary contact, the pivotal axis of said magnet being so located that pivotal movement of said magnet raises or lowers only one of the poles with respect to said stationary contact, and means for adjusting the angular position of said magnet on said base.

5. In a snap switch, a base, a stationary contact on said base, a switch arm pivotally carried on said base, a movable contact on said switch arm, an armature on said switch arm, means for adjusting the position of said armature with respect to said base when said contacts are in engagement, a permanent magnet pivotally mounted on said base on an axis parallel to the pivotal axis of said switch arm, the pivotal axis of said magnet being so located that pivotal movement of said magnet raises or lowers only one of the poles with respect to said stationary contact, and means for adjusting the angular position of said magnet on said base.

MURRELL F. KAUTZ.

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

UNITED STATES PATENTS Number Name Date 2,385,887 Shaw Oct. 1. 1945 2,410,055 Frerer Oct. 29, 1946

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