US2337001A - Snap switch - Google Patents

Description

Patented Dec. 14, 1943 2,337,001 SNAP swrron William A. Ray, Los Angeles, Calif. Application October 13, 1941, Serial No. 414,799

2 Claims.

' My present invention relates toimprovements in snap switches of the type which utilize magnetic force, and resilient means through which an actuating force opposing that of the magnet is applied to eifect snap-action of the contacts; and particularly to those of the sensitive type adapted to be actuated by means moved gradually in response to change in a condition, such as temperature or pressure. v

An object of this invention is to provide a switch of the character described which is capable of handling relatively heavy loads.

A more specific object is to provide, in a switchof the character described, a novel arrangement of the parts whereby the contacts, upon initial engagement, are firmly held in that condition and vibration between them'is substantially eliminated.

Another object is to provide, in a switch of .the type indicated, an improved means whereby,

in the opening movement of the contacts, they are held in engagement under a high contact pressure until the means for opening them-has gained considerable momentum.

Other objects and advantages of my invention will be found in the description, the drawing, and the appended claims.

,For complete understanding of the invention,

' reference maybe had to the following detailed 4 description and accompanying drawing, wherein:

Figure 1 ,is a plan view of a snap switch embodying my invention, with the cover l2 omitted;

Figure 2 is a vertical section of the switch shown in Fig. 1 with the switch cover in place;

Figure 3 is a view, partly in section, similar to that of Fig. 2 and showing the parts in their moved positions; and

Figure 4 is a transverse section taken along the line.4-4 of Fig. 1. v

In the drawing, the numeral II indicates a base, and I2 a cover for the base, both of which are made of insulating material. The peripheral edge of the cover l2 rests on a shoulder l3 of the base and is held thereon by screws (not shown) which extend through openings l4 in the base and into threaded bores in the filleted corners of the cover. The base H is notched at I 5 for the. cover bosses l6 which are bored to receive bolts by means of which the switch-unit may be mounted on a panel or the like.

Embedded in the base I! are a pair of termi nals I1 and [8. A U-shaped bracket 2| is secured on thebase by the riveted-over end of terminal I8 which extends through the mounting flange 22 of the bracket. An elongated channeled armature 23 is pivotally mounted between the arms 24 of the bracket 2! by means of a pin 25 which extends through openings in the bracket arms and the sides of the armature. To reduce the weight of the armature it is preferably apertured toward its free end, as at 29. Adjacent the top surface of armature 23 is a switch arm 28, also pivotally mounted on the bracket 2i by means of the pin 25, and connected with terminal l8 by flexible leads 21. A spring 28 is com pressed between the bottom wall of a dished portion 3| of the arm 26 and a-horizontal bent-up portion. 32 of the armature 23. The spring is held in position at its lower end by the side walls of the dished portion 3| and at its upper end by a conical depressed portion 33 of the armature portion'32. Riveted in the bottom wall of the dished portion 3! is a downwardly-faced contact element 34. The portion 3| and contact 34 ex- 7 tend loosely. throughan opening 35 in the armature 23 beyond the lower side thereof, and the flat surfaces around the dished portion 3| and opening 35 overlap so that upward movement of armamm 23 may be transmitted to-arm 26. Downward movement of the armature is transmitted to arm 26 throughspring 28; The arrangement is such that limited relative motion between the armature and switch arm is permittedgin both the opening and closing movements. I

A U-shaped permanent magnet 36, for attraction' of armature 23, rests in a socket 31 in the base H and is held there by a metal strip 38, a horizontal portion of which extends between the arms of the magnet and is fixed to the base by a screw 39. The upper end portion 4| of strip 38 extends above, and is bent over the armature to limit the upward movement thereof.

Cooperable with contact element 34 is a relatively fixed contact element 42, the lower end portion of which is threaded into a tubular metal member 43 embedded in the'base II. The contact, 42 is electrically interconnected with terminal Why a strap 44, held in place by the riveted-over ends of the terminal I! and member 43. The contact 42 serves the additional purpose of limiting the downward movement of the armature, the lower end portion being pressed 2. spring 50, held in place at its upper end by the lower end portion 5| of rod 41, which extends centrally within the coils of the spring,

and atits lower end by the conical raised portion.

52 of the armature 23. a

The operation of the device is as follows: assuming that the switch is arranged to be actuated by an arm 53,v gradually movable in response to change in a, condition, upon initial.

downward movement of rod 41 from its position shown in Fig. 2, the armature 23 will remain unmoved, due to'the force thereon of magnet Y spring 28, result in a high contact pressure at all times that the contacts are in engagement.

In the event that the contacts 34 and 42 should stick or weld, and spring 50 is not willciently strong to separate them, rod 42, by its continued movement, will directly engage the raised portion 52 of armature 23, and exert a direct contact-separating force thereon.

While I have herein shown and described a specific embodiment of my invention, I wish it to be understood that modifications may be made without departing from the spirit of the invention, and that I intened therefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a snap switch: a base; a magnet mount- .4 ed on one end portion of said base; a bracket mounted on the opposite end portion of the base;

exerts a direct force holding contacts 34 and 42 I in engagement, but upon initial movement of the armature this force is removed and the contacts are then momentarily held in engagement by the force of spring 28. This spring force is effective until the lost motion between the armature and arm is taken up, when the armature, having gained considerable momentum,

strikes'the arm, the impact separating the. contacts.

Upon subsequent reversal of change in the controlling condition, the force exerted through spring 50 on armature 23 by the actuating arm 53 will decrease, and as it approaches zero, will be insuflicient to retain the armature in its moved position against the force of magnet 36.

.The armature will now move toward the magnet causing a rapid increase in the effective magnetic force which results in a snap-action circuit-closing movement of, contact 34, the movement of armature 23 being imparted to contact arm 26 through'spring 28.

Sudden stopping of contact 34 upon engaging contact 42 tends to cause vibration, or bouncing of contact 34 with consequent arcing. However, in the present construction, spring 28, which is always under stress, tends to absorb the vibrations, and the lost motion between the dethe opposing force so that the armature is sudpressed portion 33 of armature 23 and the'upper end of contact 42 is instantly taken up when the contacts engage, and the magnetic forceholds the contacts in engagement, as shown in Fig. 2. The relative positions of the magnet, contacts, and point of actuating force application 52 with respect to the bracket, in combination with a fixed contact element mounted on the base between said magnet and said bracket; a relatively short and inflexible arm pivoted at one of its ends on the bracket, the other end of the arm extending toward said magnet and carrying a contact element cooperable with said fixed contact element; said contact elements being positioned nearer to the pivot point of said arm than to said magnet; an armature pivoted adjacent one of its ends on said bracket and on the same axis as the arm, the other end of the armature extending adjacent the magnet so that it is. constantly attracted thereby; resilient means constantly exerting a force on the armature opposing that of the magnet; means effective in its movement in one direction to increase said opposing force so that the armature is suddenly. moved away from the magnet, and subsequently in an opposite direction to decrease 2. A snap switch, as'defined in'claim 1, where-' in the portion of said armature which overlies said depression is provided with means directly engageable with said armwhen thearmature is in its fully-attracted. position.

4 WILLIAM A. RAY.

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