US2835753A - Multiple pushbutton switch with snap action springs - Google Patents

Description

May 20, 1.95.8 w. E. LEwls, JR 2,835,753

MULTIPLE PUSHBUTTON SWITCHl WITH SNAI.; ACTIGN SPRINGS Filed March 1, 1957 I y im KM n j SZ/5* /4//0//760 United States VPatent MULTIPLE PUSHBUTTON SWITCH WITH SNAP ACTON SPRINGS Walter E. Lewis, Jr., Louisville, Ky., assigner to General Electric Company, a corporation of New York Application March 1, 1957, Serial No. 643,444

Claims. (Cl. 20D-5) This invention relates to a multiple pushbutton switch and particularly to one having movable sliders for con trolling the 'operation of the movable contacts of the switch. lt is important for the movable contacts to make and break the circuit through the iixed contacts of the switch without hesitation so that there will not be at any time a narrow air gap between the movable and fixed contacts which might allow a high voltage arc to jump across the gap and burn the contacts. Since the movable contacts are directly controlled by the sliders which are in turn controlled by the pushbuttons of the switch it has been found expedient to control the movable contacts by controlling the action of the buttons.

The principal object of this invention is to provide a multiple pushbutton switch with quick acting movable contacts by furnishing each of the buttons with a novel detent spring that is capable of locking each button in the down or depressed position, and must be unlatched before another button may be fully depressed.

The further object of this invention is to provide a multiple pushbutton switch with a quick acting contact arrangement where a certain heavy pressure must be exerted on a button to depress it in order to overcome the latching action of the detent springs of a previousiy depressed button.

A still further object of this invention is to provide a novel detent spring and means for attaching the spring to the innermost end of a pushbutton of a multiple pushhutton switch.

This invention is broadly related to the pioneer pushbutton switch patent to Andrews No. 2,431,904, which is assigned to the same assignee as is the present invention. A preferred embodiment ot my invention of a multiple pushbutton switch has an insulating housing formed by a recessed base and a removable cover plate, although it should be recognized that this invention is not restricted to such construction. A plurality of pushbuttons extend through openingsv in one wall of the base while a series of parallel sliders are arranged'edgewise in the base with respect to the cover plate for controlling the actuation of the movable contacts of the switch. The innermost end of each button is provided with a detent spring of generally U-shapehaving a pair of resilient arms that cooperate with shoulders formed on opposed walls of the base for latching the buttons in the down or depressed position. Each of the sliders is provided with a series` of diagonal cam surfaces which are acted upon by the innermost ends of the pushbuttons for shifting the sliders endwise inthe base. However, once a button is fully depressed' and held down by the' latching arrangement of its detent spring, another button may not be fully depressed until enough force is exerted on that button tolovercome the holding torce of the detent spring of the' depressed button. At the time when the latching force of the detent spring is suddenly overcome, the manual! force exerted on the downwardly button is of such amount that it immediately moves that button Vto its fully depressed position. Meanwhile, the sliders will return the previously depressed button to its outermost position.

My invention will be better understood from the following description talren in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Figure l is a top plan View of a multiple pushbutton switch embodying my invention.

Figure 2 is a bottom plan view ot the switch of Figure 1 with the cover plate removed to show the internal mechanism of the switch.

Figure 3 is a cross-sectional side view taken on the lines 3 3 of Figure 1 through a fully depressed button.

Figure 4 is an isometric view showing one of the pushbuttons and a separate detent spring that is to be mounted thereon. l

Figure 5 is a view showing the coniiguration of the various movable sliders of the switch.

Referring in detail to the drawing and in particular to Figures 1 3 the switch 1li has an insulating housing corriprising a recessed base 11 that is closed by a bottoni cover plate i2. The wall 13 of the base 11 that is opposite the cover plate i2 has ya number of rectangular openings Titi in side-by-side relation for receiving pushbuttons i5 that are manually operated to control the various circuits through the switch.

rthe electrical switching mechanism is best understood with relation to the bottom plan view of Figure 2. First, there are three movable contacts liti, 17 and 18 of thin strip material arranged in a parallel relation across the bottom of the base and extending from one side to the other. A male terminal i? is permanently attached to one end of eachv of the movable contacts, and this terminal end isy then rigidly mounted between the molded parts 2Q of the base` in a well-known manner. Looking at Figure 3, the male terminals 19 extend perpendicularly of the movable contacts and outwardly through the cover plate 12. Fixed contacts 2d, 21 and 22 are arranged on the side of the base 11 that is opposite the male terminals 1.9. These fixed contacts have screw terminals 23 that extend through openings in the cover plate 12 at the edge thereof and. lie in substantially the same plane as the cover plate.

Sidewise movement of the movable contacts 16, 17 and 18 will bring them into engagement with the lixed contacts 2li-22. The mechanism for affecting this movement represents a series of live movable sliders shown in detail in Figure 5, and interposed between the pushbuttons 15 and the movable contacts as illustrated in Figure 3. There are two outer metal sliders 25 and 26 and three intermediate insulating sliders 2'7, 28 and 29. These sliders are grouped together and assembled edgewise in the basey 1l to lie perpendicular to the cover plate 12, Looking at Figure 5, the lower edge of each slider has a series of diagonal cam surfaces or notches 30 which cooperate withV the innermost ends of the pushbutton 15 so that the depression of any one of the buttons will shift the sliders in a predetermined manner. Furthermore, each slider has a series of strut members 31 on the edge opposite the cam surfaces 3i? which are adapted to bear against the inner surface of the cover plate 12 in a sliding relationship. Opposed side partitions 32 of Figure 2 are formed in the base 11 to limit the sliders 25-29 to only longitudinal movement.

The outer metal sliders 25 and 26 do not engage the movable contacts 16, 17 and 18; however, they serve as a mechanical interlock to insure that only one pushbutton 15 is fully depressed at any one time. A study of the cam surfaces 3!) of the two metal sliders 25 and 26 shows the surfaces of one slider to be inclined in the opposite direction from such surfaces in the other slider. Accordingly, both metal sliders may shift when an adjacent button is' depressed and the down button will be forced to its outer position. Slider 27 is coupled with the movable contact 16 by means of a slot 33 in the edge of the slider iu which the movable contact is seated. A similar slot 34 is cut in slider 28 for receiving the movable contact 17. Lastly, a slot 35 in slider 29 receives the movable contact 18.

All of the pushbuttons 15 are identical so that reference will be made to only one of them as illustrated in Figure 4. The button 15 has a hollow shank portion 24 of generally rectangular cross-section and an enlarged bifurcated end 36 that straddles the sliders 25-29, as seen in Figure 3. A U-shaped detent spring 37 of thin strip material such as spring steel is assembled to the end 36 of the button to serve as a latching mechanism to hold the button in its depressed position. Spring 37 has a symmetrical shape with a base 38 and two resilient arms 39 with the free ends rolled inwardly toward each other to form latch portions 40. The base 38 of the spring extends across the bottom of the bifurcated end 36 of the button so that it will engage the diagonal cam surfaces 30 of the sliders. An embossment 41 at the mid-portion of the base 38 has a rounded shape for making line engagement with the cam surfaces.

The spring 37 is designed to snap over the bifurcated end 36 of the button 15 so that it will be carried thereby. The base 38 of the spring lits into a bottom depression 42 of the button, while the arms 39 extend along the sides of the button and within the depressions 43. Actually, the side depressions 43 are both inclined in a manner to be deeper at the end remote from the bottom depression 42. The arms 39 of the spring 37 are not parallel, but

rather they normally diverge outwardly from the base 38 so that they are actually under compression when assembled between the parallel side 4walls 44 of the base 11 as seen in Figure 3. The inner surface of each side wall 44 has a shallow groove 45 that extends in the direction of the movement of the button 15 and terminates before it reaches the top face 13 of the base by a distance that is slightly less than the stroke of the button. Thus, shoulders 46 are established on the inner surfaces of the walls 44 within the grooves 45. The arms 39 of the detent spring flex outwardly into the grooves 4S when a button 15 is in its fully depressed position. In so doing, the rounded latch ends 40 of the arms 39 bear against the shoulders 46 and prevent the outer movement of the button 15. When manual pressure is exerted against one of the up buttons, that button will move downwardly to shift some or all of the sliders thereby exerting pres- -sure against the down button to force it to is outermost position. Only when this force is large enough to compress the latching arms 39 from engagement with the shoulders 46 will it be possible `for the down button to rise. However, when the arms 39 become disengaged from the shoulders 46 the down button will move rapidly since its force resisting movement has vanished. Accordingly, the buttons as well as the sliders and movable contacts will have a definite snap action.

The detent springs 37 serve two primary functions; namely, to provide the switch with a snap acting mechansm and also to latch the buttons in their fully depressed position so that the sliders will exert side pressure against the movable contacts to hold them lirmly against the xed contacts. The switch parts are so arranged that the movable contacts do not make or break engagement with the fixed contacts until the detent spring 37 of the down button has become disengaged from the shoulders 46 and is rapidly moving to the up position. It is only during this rapid movement of the button that the movable contacts change the circuits of the switch. The movable contacts might flex slightly as the sliders begin to shift,

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but the movable contacts are provided with a denite snap action for both the opening and closing of the switch.

Having described above my invention of a novel pushbutton switch using movable contacts of cantilever construction it will be well recognized by those skilled in this art that by the simple means of detent springs on each of the buttons it is possible to exert positive pressures to hold the movable contacts against the fixed contacts, to provide the movable contacts wit-h a snap acting mechanism, and to hold the down button in a fully depressed position with a latching arrangement that requires a certain large downward force on a button before the down button will start to rise and permit another button to bc depressed. A switch embodying my invention is both in experience to manufacture and easy to assemble. All of the switch parts are assembled through the open bottom wall of the switch base, and the cover plate is fastened to the base to form a completely enclosed housing of insulating material which is of compact size.

Modifications of my invention will occur to those skilled in this art, and it is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed, but that it is intended to cover all modifications which are within the true spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A multiple pushbutton switch comprising an insulating housing and a series of parallel slides, each slider having diagonal cam surfaces, a plurality of pushbuttons slida'bly mounted through one wall of the housing, the inner end of each buttonhaving means for engaging the ycam surfaces of one or more `of the sliders to affect the shifting of the sliders, the sliders cooperating with a scries of movable contact members for opening and clos.- ing the circuits through the switch, and a U-shaped detent spring carried over the inner end of each button in planes transversely of the sliders, the spring having an outwardly divergent resilient arm at each side of the button with an inwardly-turned hook end in locking engagement with the button for holding the spring in place, the opposite walls of the housing adjacent the resilient arms being undercut to form shoulders which oppose the hook ends of the arms of the detent spring, whereby the switch is provided with a snap action since a button may not be fully depressed until the resilient arms of the detent spring of a previously -depressed button are deliected'to slide by the shoulders.

2. A multiple pushbutton switch comprising an insulating housing with a recessed base and a removable cover plate, a wall of the housing having a plurality of openings each for receiving a manually operable pushbutton that extends inwardly of the housing, and a series of parallel sliders perpendicularly arranged with respect to the cover plate and having diagonal cam surfaces which cooperate with the innermost ends of the pushbuttons so that the buttons are capable of shifting the sliders back and forth with respect to each other, and a group of movable contacts mounted in the base each being engaged 'by a slider so that the movement of the sliders control the movement of such contacts, and a U-shaped detent spring fitted over the inner end of each button in a plane transversely of the sliders, each spring having a resilient arm at each side of the button with an inwardlyturned latching end that hooks over cooperating shoulders of the button so that lthe spring is fastened thereby, and opposing walls of the housing adjacent the resilient arms, the walls being undercut to form shoulders that oppose the latching ends of the arms of the detent spring, so that the switch is provided with a snap action since a button may not be fully depressed until the resilient arms of the detent spring of a previously depressed button are deected to slide by the shoulders of the housing.

3. A multiple pushbutton switch as recited in claim 2 wherein the innermost end of each pushbutton is bifur- 5 cated to straddle the sliders, `and the sliders are notched along one edge thereof to form the diagonal cam surfaces, the base portion of the U-shaped detent spring serving to engage the cam surfaces ofthe sli-ders and control the movement thereof.

4. A multiple pushbutton switch comprising a hollow housing, a series of parallel sliders stacked together in a manner edgewise to the 'bottom wall of the housing, the top Wall of lthe housing containing a plurality of openings, each opening receiving a manual-ly operable pushbutton that extends inwardly of 'the housing, the top edge of each slider having diagonal cam surfaces that are acted upon by the buttons for shifting the sliders in a predetermined manner, and a group of movable contacts mounted in the housing, each movable contact being joined with one of the said sliders for movement therewith, the inner end of each button being enlarged an-d bifurcated to straddle the stack of sliders, the bifurcated end of each button having a depression in its bottom and side surfaces for receiving therein a U-shaped detent spring that lies in a plane transversely of the sliders, each spring having a base portion engaging the cam surfaces of the sliders and an outwardly-divergent resilient arm in each side depression of the button, each arm having an inwardly-turned hook end in locking engagement with the button for holding the spring in place, and opposing walls of the hous ing adjacent the resilient arms, the walls being undercut to form shoulders that oppose the hook ends of the arms of the detent spring, so that the switch is provided with a snap action.

5. A pushbutton switch as recited in claim 4 wherein the depressions in the side surfaces of each button are inclined in a converging manner to be deeper at the end remote from the bot-tom depression, so as to accommo date the compression yof the resilient arms as they slide past the shoulders of the housing.

References Cited in the iile of this patent UNITED STATES PATENTS 843,901 Lewis Feb. 12, 1907 2,622,160 Werner Dec. 16, 1952 2,634,340 Batcheller Apr. 7, i953 20 2,652,470 Batchener sept.15,1953

FOREIGN PATENTS 161,948 Switzerland Aug. l, 1933

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