US3310762A - Pushbutton snap action switch with permanent magnet latching means - Google Patents

Description

March 21, 1967 GQETZ 3,310,762

PUSHBUTTON SNAP ACTION SWITCH WITH PERMANENT MAGNET LATGHING MEANS Filed Feb. 1, 1966 2 Sheets-Sheet 1 INVENTOR.

ERNEST F GOETZ March 21, 1967 E. F. GOETZ 3,310,762

PUSHBUTTON SNAP ACTION SWITCH WITH PERMANENT MAGNET LATCHING MEANS Flled Feb 1, 1966 2 Sheets-Sheet 2 INVENTOR.

ERNEST F GOETZ United States Patent 3,310,762 PUSHBUTTON SNAP ACTION SWITCH WITH PER- MANENT MAGNET LATCHING MEANS Ernest F. Goetz, Roanoke, Va., assignor to General Electric Company, a corporation of New York Filed Feb. 1, 1966, Ser. No. 524,148 1 Claim. (Cl. 335-188) This invention is directed to a device for interrupting energy delivered in an electrical circuit, and, more particularly, relates to a manually operated circuit breaker and the like, sometimes referred to as a snap-action switch.

Essentially the invention resides in the provision of the linear alignment of mechanical components in a device of this type for economizing space in respect to ganged units for enabling rapid and reliable operation, and for permitting easy access to the actual contacting members in respect to the inspection and maintenance.

, In many applications such 'as in cam operated switches it is desirable to contain the ganged contact operating mechanisms to a small space. In the usual lever and overcenter travel contact operating mechanisms a great amount of valuable space is occupied by the leverage mechanism.

It is therefore an object of this invention to provide an improved construction which will produce a switch having its components so arranged whereby the usual toggles, levers, and overcenter travel mechanisms are completely eliminated, thereby allowing for increased density of ganged arrangement of snap-action switches.

The basic goal of snap-action switches is to provide reasonably fast contact operation by a relatively slow moving operator such as in a cam switch or a float switch. The usual method in which this is attained is by lever and overcenter travel mechanisms, wherein linear forces 'are transferred to angular motions such as in bearing pins, through which mechanical life of the switch is curtailed.

Another object of this invention is to provide an improved snap-action mechanism in which all the moving components are arranged linearly, thereby increasing the mechanical life of the switch by eliminating the wear associated with the usual toggles, levers, and overcenter travel mechanisms.

In all electrical circuit interrupting devices there is a possibility that the electrical contacts, through the action of the electrical arc, become welded in the closed position, so that the force produced by the springs associated with the overcenter travel mechanisms is insufficient to overcome the "weld and thereby fail to perform the primary function of the component which is to interrupt the circuit.

Another object of this invention is to provide an improved construction which Will produce a switch in which the contact opening feature is completely failsafe.

When individual circuit breakers are mounted in close proximity to each other as in a ganged arrangement in a cam operated mechanism, or in 'any location where space for inspection and maintenance is restricted, it becomes essential that under those circumstances the entire snapaction switch has to be removed. This usually involves disconnecting the electrical wiring with which the switch is associated and the removal of mounting screws whereby the switch is affixed to the cam operator mechanism or the like.

It is therefore yet another object of this invention to provide an improved construction which will produce a switch in which inspection and maintenance of the electrical contacts may be performed without removal of the entire switch from its supporting members.

, 3,310,762 Patented Mar. 21, 1967 The invention is set forth with particularity in the appended claim. The principles and characteristics of the invention, as well as other objects and advantages are revealed and discussed through the medium of the illustrative embodiments appearing in the specification and drawings which follow.

In the drawings:

FIGURE 1 illustrates a cutaway view of the snap-action switch which is provided with the in-line construction.

FIGURE 2 of the drawings shows a cross-sectional view of snap-action switch, showing the relationship of the springsand other moving parts with the stationary parts.

FIGURE 3 shows the movable contact unit, removed from the switch as during contact tip inspection.

Referring now to FIGURE 1, the housing consisting of a front portion and back portion 11 and 13', respectively, is shown assembled and fastened together by screw 15. The front portion 11 is partially broken away to show hole 17 in back portion 13 which is used for fastening front portion 11 to back portion 13 with a screw similar to screw 15. Stationary contact supports 21 and 23, supporting contacts 29 and 31, respectively, are shaped to fit in slots therefore provided in the housing front and back portions 11 and 13, respectively, and contain threaded holes for connection screws 25 and 27.

FIGURE 3 shows the movable contact unit consisting of pushrod 43 having an enlarged cylindrical portion 49 which forms a shoulder to which movable contact support 41 with electrical contacts 45 and 47 is urged by contact spring 39. Pushrod guide 37 which is slidably assembled onto pushrod 43 and which is held in position by O- ring 36 which is inserted into a notch therefore provided in pushrod 43. Pushrod guide 37 is provided with two depressions 32 and 34 into which the specially shaped ends 33 and 35 of stationary contact supports 21 and 23 are fitted as shown in FIGURE 1.

Removal of the movable contact unit is accomplished by compressing contact spring 39 so that stationary contact supports ends 33 and 35 become disengaged from depressions 32 and 34 in pushrod guide 37. A 45 counterclockwise twist of the pushrod guide will allow retraction of the entire movable contact unit from the switch.

When the movable contact unit is installed in the switch, contact spring 39 urges movable contacts 45 and 47 to engage with stationary electrical contacts 29 and 31, respectively.

The cylindrical portion 49 of the pushrod 43 passes slidably through a central opening in a first magnetizable stationary member 53, which is located in cavity 55 therefore provided in the front and back portions of the housing 11 and 13, respectively.

The actuating portion .of the snap-action switch consists of 'a button 61 having within it a concentric cavity 63 as shown in FIGURE 2. A conical portion 79 of spring seat 69 nests pivotally within a conical cavity 81 of button 61. The cross-sectional view in FIGURE 2 shows stem guide 71 connected to magnet 51 having stem 65 slidably passing through it. The trip spring 67 which passes into cavity 73 of stemguide 71 and rests against the spring seat 69 is not under compression until button 61 is depressed. The return spring 75 urges against spring seat 69 at one end while the opposite end presses against the second stationary member 77.

In operation with the switch in the normal position, as illustrated in FIGURE 2, return spring 75 which is a relatively low gradient spring, urges button 61 against seat projection 68 of housing 11 and 13.

Trip spring 67, a relatively high gradient spring, is practically at free length.

-member 53. Together with the magnet 51, pushrod 43,

supporting movable contacts 45 and 47, is moved in the direction of first stationary member 53. This causes movable contacts 45 and 47 to disconnect from stationary contacts 29 and 31, respectively, thereby opening the electrical path consisting of terminal screw 25, stationary contact support 21, stationary contact 29, movable contact 45, movable contact support 41, movable contact 45, stationary contact 31, stationary contact support 23 and connection screw 27.

Assuming now that the movable contacts 45 and 47 have become welded to stationary contacts 29 and 31, respectively, then, continued stroke applied to button 61 will positively break the weld and open the electrical path.

When the pressure on button 61 is removed, return spring 75 urges the button toward its normal position. The compressive force thus removed from trip spring 67 allows the spring to expand to free length, hence removing the pressure from magnet 51. The magnetic attraction between magnet Sland first stationary member 53 is now the only force to maintain the position of the magnet 51, pushrod 43 and associated contacts 45 and 47,

7 against the compressive force of contact spring 39. However, just before button 61 reaches its normal position, the head 66 of stem 65 engages with magnet 51 and the combined force of return spring 75 and contact spring 39 break the magnetic seal between first m'agnetizable stationary member 53 and magnet 51. This combined force persists until button 61 reaches its normal position, at which time the force of contact spring alone returns the magnet 51, pushrod 43 and electrical contacts 45 and 47 to the normal position, with the magnet coacting with second stationary member 77, as represented by FIGURES 1 and 2.

The electrical path from terminal screw 25 through the components named above to terminal screw 27 is now closed, hence allowing electrical current to flow through the snap-action switch.

While the invention has been explained 'and described with the aid of particular embodiments thereof, it will be .understood that the invention is not limited thereby and that many modifications retaining and utilizing the spirit thereof without departing essentially therefrom will occur to those skilled in the art in applying the invention to specific operating environments and conditions. It is therefore contemplated by the appended claim to cover all such modifications as fall within the scope and spirit of the invention.

What is claimed is:

A circuit breaker having fixed and movable contacts, a contact operating spring normally urging said contacts together, positive operating means for ultimately separating said contacts, a trip spring coacting with said operating means for initially separating said contacts, a return spring coacting with said contact operating spring to resist said operating means, said operating means including a permanent magnet, a first, fixed magnetizable member coacting with said magnet to provide snap-action to bring said contacts together, a second, fixed magnetizable member coacting with said magnet to provide snap-action to separate said contacts, a fixedly detachable abutment for said contact operating spring, the tension of said spring against said abutment normally retaining the alignment of said movable contacts with said fixed contacts, and a support engaging and disengaging said abutment upon its displacement whereby the alignment of said contacts is disrupted to permit said movable contacts to be removed from said circuit breaker.

References Cited by the Examiner UNITED STATES PATENTS 2,451,176 10/1948 Schellman 20077 2,748,216 5/1956 Schneider et al ZOO-77 2,848,575 8/1958 Hahn 200-77 3,175,060 3/1965 Crissinger et al 335205 BERNARD A. GILHEANY, Primary Examiner.

J. J. BAKER, Assistant Examiner.

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