US3828148A

US3828148A - Multi-position electrical switch and spring biasing means for universal-type actuator

Info

Publication number: US3828148A
Application number: US00352900A
Authority: US
Inventors: J Roeser
Original assignee: Otto Engineering Inc
Current assignee: OTTO ENG INC US; Otto Engineering Inc
Priority date: 1972-09-20
Filing date: 1973-04-20
Publication date: 1974-08-06
Anticipated expiration: 1991-08-06

Abstract

A multi-position electrical switch assembly with an elongated actuator means contains resilient means normally biasing the actuator means to a center off position. The actuator means is pivotally movable between a center off position to a plurality of switch on positions whereby a selected switch is actuated. The interior of the casing is hermetically sealed by an O-ring disposed below the equatorial line of the actuator means ball and socket joint of the housing.

Description

Umted States Patent 1191 1111 3,828,148 Roeser Aug. 6, 1974 MULTI-POSITION ELECTRICAL SWITCH 2,374,868 5/1945 Krieger 200/6 A ux EAN F 2,521,489 9/1950 Sorensen 200/6 A X G:?VSEI;:;TLGTBYI$I:CGT13ATO?( OR 2,686,233 8/1954 Obszarny 200/6 A 2,782,279 2/1957 Heusser 1. 200/6 BA X [75] Inventor: John O. Roeser, Arlington Heights, 2,808,476 10/1957 Elliott 200/6 A In, 2,984,720 5/1961 Fisher 200/6 A x 3,031,547 4/1962 Sorenson 200/6 BA X [73] Assigneez Otto Engineering, Inc., 3,251,956 5/1966 Rasor et al........ 200/6 B X Carpentersville, 111. 3,272,950 9/1966 Greenhut 200/166 BF [22] Filed: Apr. 20, 1973 3,401,240 9/1968 Groves 200/6 BA [2]] Appl- N04 352,900 Primary Examiner-James R. Scott Related US. Application Data [63] Continuation-in-part of Ser. No. 290,482, Sept. 20,

I972, abandoned. [57] ABSTRACT A multi-position electrical switch assembly with an 1 1 200/6 A, 17 R, 200/153 K, elongated actuator means contains resilient means 200/166 BF, 200/172 R normally biasing the actuator means to a center off 1 f H0111, 25/04,H01h 21/80 position. The actuator means is pivotally movable bel 1 Field of Search 200/6 A, 6 6 BA, 6 tween a center off position to a plurality of switch on 200/17 R, 1 166 166 BF, 153 H, 153 positions wherebya selected switch isactuated. The

K, 172 R; 74/471 XY, 473 P interior of the casing is hermetically sealed by an O- ring disposed below the equatorial line of the actuator 1 1 References Cited means ball and socket joint of the housing.

UNITED STATES PATENTS 2,100,642 11/1937 Geyer 200/172 R ux 23 Clam, 15 D'awmg F'gures PATENTED B 6 74 QHLEI 1 BF 5 FIGJ PATENTEB AUG 61974 saw u or 5 FIG.

I n F MULTI-POSITION ELECTRICAL SWITCH AND SPRING BIASING MEANS FOR UNIVERSAL-TYPE ACTUATOR RELATED APPLICATION This application is a continuation-in-part of my prior co-pending US. Pat. application entitled Multi- Position Electrical Switch, Ser. Noj 290,482, filed Sept. 20, 1972, now abandoned.

BACKGROUND -This invention relates to a multi-position electrical switch of the type which finds particular utility in the aircraft industry. Such a switch might typically be mounted on the top of the control or joy stick, the switch being used by the pilot to activate trim tab servomotors to balance out the airplane laterally and longitudinally and to make precision maneuvers. A switch of this type generally requires four different on positions for independently operating four different circuits.

Although electrical switches for this purpose have been available for many years, modern electronic circuits and the demands for high performance aircraft has resulted in new requirements for the switches. For example, in many instances it is necessary to hermetically seal the switch in order to protect the mechanism. Also, newelectronic circuitry frequently operates at very low electrical energy levels, low milliamps and low voltage. In addition, the use of complicated circuitry has required that more electrical functions be available from the switch. However, since it may be desirable to mount the switch in the joy stick, the increased electrical circuitry should be mounted within a casing of such a size that it can be conveniently mounted in a conventional size joy stick.

SUMMARY The invention provides a switch that not only has more electrical circuitry but is smaller in size. The switch includes 12 terminals and four separate poles that are electrically independent of each other, each pole having three terminals. Each pole includes a unique switching lever'which is pivotally mounted intermediate its end on a common terminal to provide a pair of lever arms which extend inwardly and outwardly from the fulcrum provided by the common terminal. The actuator engages the inner lever arm of each lever when in the center off position and thereby forces each lever away from the other two terminals of each pole.

When the actuator is moved into one of its on positions,

it passes over the fulcrum of one of the levers and forces the outer lever arm outwardly against the other two terminals of the pole. The angle of each lever relative to the actuator is such that the spring-biased actuator is urged to return to its center off position when the operating force is released, and when the actuator returns over center, it provides a positive force which moves the lever away from the terminals. A conical return spring may be used which provides a progressively greater return force as the actuator moves away from center and which does not exert undesirable forces on the mounting ball of the actuator. The interior of the casing is hermetically sealed by an O-ring which sealingly engages the mounting ball of the actuator below I the equator of the ball as the ball rotates. The ball includes diametrically opposed projections to restrain rotation of the ball and the shaft about the longitudinal axis of the shaft, and the O-ring is positioned far enough below the center of the ball to avoid contact with the projections. The O-ring remains stationary as the ball rotates about any axis perpendicular to the axis of the shaft and maintains sealing engagement with the rotating ball.

DESCRIPTION OF THE DRAWING The invention will be explained in conjunction with an illustrative embodiment shown in the accompanying drawing, in which FIG. 1 is a longitudinal sectional view of a switch formed in accordance with the invention showing the actuator in the center off position;

FIG. 2 is a view similar to FIG. 1 showing the actuator in one of its on positions;

FIG. 3 is a top plan view of the terminal base of the switch with some of the terminals and switch levers removed; I

FIG. 4 is a sectional view of the terminal base taken along the line 4-4 of FIG. 3;

FIG. 5 is a plan view of one of the switch levers;

FIG. 6 is a side view of FIG. 5;

FIG. 7 is a plan view of one of the common terminals upon which the switch lever is mounted;

FIG. 8 is a side view of FIG. 7;

FIG. 9 is a bottom plan view of the actuator-guiding insert;

FIG. 10 is a top plan view of the actuator-guiding in sert;

FIG. 11 is a schematic view illustrating the movement of the operating shaft without restraint by the guide means;

FIG. 12 is an enlarged fragmentary view of a portion of FIG. 11 with the seal means shown broken away.

FIG. 13 is a view similar to FIG. 1 showing a modified return spring for the actuator;

FIG. 14 is a view similar to FIG. 2 showing the modified return spring; and

FIG. 15 is a plan view of the return spring of FIGS. 13 and 14.

DESCRIPTION OF SPECIFIC EMBODIMENT Referring now to the drawing, the numeral 15 designates generally an electrical switch which includes a casing or housing 16 and an actuator or operating shaft 17. The actuator is movable by means of an operating button 18 mounted on the top end of the actuator into four separate on positions in which one of four switch levers 19 are moved into engagement with a pair of outer terminals 20 which extend outwardly through the casing. In FIG. 1 the actuator is in its center off position in which it is aligned with the longitudinal axis of the casing and in which it holds all of the switch levers 19 out of engagement with the outer terminals 20. In FIG. 2, the actuator has been moved by the operating button 18 into one of its on positions in' which it forces the switch lever 19 on the right into engagement with two of the outer terminals 20.

The casing 16 includes a terminal base 21 which includes an outer generally cylindrical wall 22, a bottom wall 23, and four interior walls 24 (FIGS. 3 and 4) which extend radially inwardly from the outer wall to the center of the terminal base and which divide the terminal base into four quadrants. The bottom wall 23 of the terminal base is provided with an inner slot 25 and a pair of outer slots 26 in each of the quadrants formed by the interior walls. An inner or common terminal 27 is received in each of the slots 25 and extends through the bottom of the terminal base, and an outer terminal 20 is received in each of the outer slots 26. The lower quadrant of the terminal base is shown in FIG. 3 without the

terminals

20 and 27 inserted in the slots, and the right quadrant is shown with the terminals in position. Each of the remaining two quadrants of the terminal base shown in FIG. 3 also includes a switch lever 19, which is seen to be generally triangularly shaped (see also FIGS. 5 and 6). As will be explained more fully hereinafter, each of the switch levers 19 is pivotally supported by the common or inner terminal 27 and may be pivoted outwardly into engagement with the two outer terminals 20 of the quadrant.

Referring now to FIGS. 7 and 8, each common terminal 27 is seen to be formed from a flat strip of metal having good electrical conductivity, such as silvercoated brass, and the upper end thereof is punched or stamped to provide an inwardly extending T-shaped mounting bar 28 and a pair of lateral fingers 29 which are spaced from the mounting bar. The lower end of the terminal may be provided with an opening 30 to facilitate connection of an electrical lead wire. Each of the switch levers 19 is formed of electrically conductive material such as metal and includes a generally triangular contact portion 31 (FIGS. 5 and 6) and a mounting portion 32 which includes a central lever arm portion 33 and a pair of U-shaped mounting brackets 34. The end 35 of each of the U-shaped mounting brackets 34 is spaced from the plane of the lever arm 33 by a distance slightly greater than the thickness of the mounting bar 28 of the common terminal.

The triangularly shaped contact portion 31 of the switch lever includes a spring-retaining finger 36 which is punched out of the plane of the contact portion and extends perpendicularly thereto. A contact 37 is mounted on the switch lever adjacent each of the outer apices of the triangular contact portion, and each contact includes a spherically curved contact face 38.

Each switch lever is mounted on the associated common terminal 27 by inserting the T-shaped mounting bar 28 of the terminal into the U-shaped support brackets 34 of the lever through the space between the ends 35 of the brackets and the lever arm 33. Since the spacing between the ends of the U-shaped brackets and the lever arm 33 is just slightly greater than the thickness of the T-shaped mounting bar and less than the dimension A of the mounting bar (FIG. 8), once the mounting brackets have been inserted over the mounting bar and the lever is rotated to the position illustrated in FIGS. 1 and 2, the lever will be retained on the mounting bar but may rotate thereabout.

Referring now to FIGS. 1 and 2, a helical coil spring 40 is positioned within a recess 41 (FIG. 3) in the terminal base between the outer terminals 20 of each quadrant and biases the switch lever upwardly away from the outer terminals. The spring 40 is held in position on the switch lever by the spring-retaining finger 36. An annular washer 42 of insulating material is supported on top of the cylindrical wall 22 of the terminal base and prevents the switch levers from being pushed beyond the positions illustrated in FIG. 1 by the springs 40 or the actuator.

An outer generally cylindrical main housing portion 43 includes a transverse ledge or shoulder 44 which retains the washer 42 against the terminal base and a bottom tubular portion 45 which is ensleeved over the terminal base. The main body portion 43 is provided with upper and lower

cylindrical recesses

46 and 47 which are joined by an intermediate recess 48. A generally cylindrical shaft-guiding insert 49 is received by the upper recess 46, and the actuator 17 extends through the shaft-guiding insert 49 and the

recesses

48 and 47.

The actuator 17 includes an elongated shaft 51 hav- 4 ing a cylindrical lower end portion 51a which telescopingly receives a plunger 52. The plunger 52 terminates in a hemispherical nose 53 which engages the switch levers l9, and the plunger is urged to telescopingly extend downwardly by a coil spring 54 which is compressed between the nose 53 and a washer 55 on the shaft which engages a radially enlarged cylindrical shaft portion 51b.

A mounting ball 57 is non-rotatably received on an intermediate portion 51c of the shaft which has a rectangular'cross section, and the upper end 51d of the shaft, which is also of rectangular configuration, nonrotatably receives sleeve 58 on the operating button 18. The button is secured to the shaft by a rivet 59, and a collar 57a on the ball spaces the sleeve 58 upwardly from the spherical surface of the ball. The mounting ball is received by a recess within the shaft-guiding insert 49 defined by spherical walls 60 (FIG. 9) and is held thereby against a spherical surface 61 (FIG. 1) on the main body portion 43 of the casing.

The mounting ball and the shaft are prevented from rotation about the longitudinal axis of the shaft by pins 62 which project outwardly at diametrically opposed locations on the equator of the ball and which are received by vertically extending slots 63 in the insert 49. The projections 62 prevent rotation of the ball about the longitudinal axis of'the shaft but permit the ball to rotate about any axis perpendicular to longitudinal axis of the shaft. This movement of the ball and the shaft is illustrated in FIGS. 11 and 12, which schematically show shaft 51 and ball 56' having pins 62'. When the shaft is in its centered position it lies along vertical axis x--x. Horizontal axis y-y passes through the pins 62', and horizontal axis zz extends perpendicularly to both of the axes x-x and y-y. The cooperation between the pins 62' and the slots 63 within the casing prevent the ball and the shaft from rotating about the axis x-x or through any axis which extends along the shaft regardless of the position of the shaft. However, the ball and shaft are free to rotate about the axes y-y and zz or about any other axis which is perpendicular to the shaft regardless of the position of the shaft. Accordingly, in the absence of other means for guiding or restricting movement of the shaft, the shaft may move freely anywhere within the cones designated 64a and 64b. The actuator is pivoted by means of the actuating button 18, which may include circular grooves or serrations 18a to provide good frictional engagement with the thumb of the operator.

The interior of the switch is hermetically sealed by an O-ring 65 which is received in a generally V-shaped groove 66 in the main body portion 43 of the casing below the horizontal midplane or equator of the mounting ball 57. The O-ring and the groove lie in a plane which extends perpendicularly to the longitudinal axis of the casing, and the O-ring is retained within the groove by a washer 68 which is held between the insert 49 and the main body portion 43 of the casing. In the embodiment illustrated the inner peripheral portion of the washer extend upwardly out of the plane of the remainder of the washer to form a frusto-conical upper wall 69 for the groove 66. However, I have found that a flat washer may be used to retain the O-ring.

The O-ring is compressed by the mounting ball 57 when the insert 49 is positioned over the shaft and secured to the main body portion of the casing, as by epoxy resin, and the upper wall of the O-ring recess 69 and the bottom wall 70 both extend radially toward the center of the ball, or perpendicularly to the surface of the ball, to permit the O-ring to sealingly engage the ball while it rotates without permitting the O-ring to be pinched. The O-ring is formed of suitable resilient, compressible material such as Silastic rubber. The O- ring remains stationary while maintaining a seal with the ball and permits rotary action of the ball and shaft. The sealing action of the O-ring can be seen in FIG. 12 which schematically illustrates the shaft 51 and the ball 57 with the O-ring 65 shown broken away. The O- ring will maintain a seal against the ball regardless of the direction in which the ball rotates.

The particular switch. illustrated includes means for guiding the movement of the operating shaft so that it may move only in two perpendicular planes which extend through the longitudinal axis of the switch casing. These planes bisect thefour quadrants of the terminal base so that pivoting movement of the shaft will move the plunger 52 of the shaft along the center line of one of the switch levers 19. Referring to FIG. 10, the upper portion of the shaft-guiding insert 49 is provided with a generally cruciform-shaped recess 72 defined by four radially outwardly extending recesses 73, each of which include a pair of outwardly extending side walls 74 and a vertically inclined end wall 75 which extends toward the center of the ball 57 (see also FIG. 2). The cruciform recess guides the upper portion of the actuator, particularly in the end portion of the travel of the actuator, and prevents the actuator from being moved too far.

Other guide means for the actuator are provided by the interior walls 24 of the terminal base shown in FIGS. 3 and 4. These interior walls not only provide insulation between adjacent poles of the switch, but the upper, vertically extending edge 24a of each wall guides the nose 53 of the plunger into the center of the desired quadrant. These straight edges 24a are also effective in preventing movement of the plunger from the center line of the switch lever 19 when the plunger is in the actuated or on position shown in FIG. 2.

From the foregoing it is seen that the invention provides a five-position switch with four separate poles, one in each quadrant of the terminal base, each pole being electrically independent of the other. Each pole has three terminals, one inner or common terminal 27 and a pair of outer terminals 20. The circuit of each pole is made from the common terminal of that pole through the electrically conductive switch lever 19 to the two independent terminals of the pole. Only one pole can be closed at a time, and the electrical circuitry is four pole, single throw, double make.

When the actuator is in the center off position shown in FIG. 1, the nose 53 of the plunger engages the short lever arm portion 33 of each of the levers 19 inwardly of the fulcrum provided by the T-shaped mounting bars of the common terminals 27, and the spring 54 urges the plunger downwardly to force the contacts of the spring levers away from their associated outer terminals 20.

When the actuating button 18 is moved to pivot the actuator and to move the plunger into one of the four quadrants, the nose 53 of the plunger passes over the fulcrum provided by the common terminal in that quadrant and engages the portion of the switch lever outwardly of the fulcrum. This portion of the switch lever also acts as a lever arm, and the spring-urged plunger forces the switch lever downwardly against the bias of the spring 40 until the contacts 37 of the spring lever engage the curved upper ends of the outer terminals 20. The plunger is forced to retract when it is moved to one of its on positions, and the force exerted by the spring 54 through the plunger against the switch lever is substantially shared by all three support points for the switch lever, i.e., the two terminals 20 and the fulcrum provided by the common terminal. This results in a very desirable high contact force which gives reliable electrical contact. This contact-making reliability is further enhanced by the curved face of the contacts and the curved upper ends of the terminals 20 which provide very small areas of contact and therefore high contact pressure.

When the actuator is in an on position, the switch lever 19 engaged by the plunger still extends at an acute angle with respect to the longitudinal axis of the actuator. The tendency of the plunger to extend under the force exerted by the spring 54 therefore urges the plunger to slide down the switch lever to return to the centered position of FIG. 1, and when the force on the actuating button 18 is removed, the actuator will return to the center off position. As the nose 53 of the plunger moves over the fulcrum and engages the short inner lever arm 33 of the switch lever, the contacts of the switch lever are forced away from the terminals 20. The high force exerted by the plunger on the switch lever as it returns to its centered position, which might be of the order of 1 /2 pounds, provides enough force to break any weld or sticking that might otherwise occur at the contacts. The compression springs 40 under the switch levers also tend to move the contacts away from the terminals, but these smaller springs are primarily intended to maintain the switch levers in their raised positions when the actuator is engaging one of the other switch levers.

FIGS. 13 and 14, in which like reference numerals designate like parts, illustrate a switch which is provided with a modified plunger-return spring 154. The switch includes an actuator 17 and four switch levers 19 as hereinbefore described, and the actuator is movable into each of the four quadrants of the switch housing to operate the switch lever therein.

The spring 154 is spirally wound in the form of a cone, having a wide diameter end 155 and a narrow diameter end 156. The conical spring is invertedwithin the switch housing, and the wide diameter end engages the upwardly converging frusto-conical wall or shoulder 157 of the main housing portion 43 which joins the

recesses

47 and 48 therein. The washer 55 shown in FIGS. 1 and 2 which provided a stop for the helical spring 54 is not needed for the conical spring and may be eliminated. The lower end of the conical spring engages a cylindrical sleeve 158 which fits over the cylindrical portion of the plunger 52 and engages the nose 53 thereof.

In the specific embodiment illustrated the actuator 17 is adaptedfor use with the conical spring 154 by inserting the sleeve 158 over the plunger. However, it is to be understood that the plunger and sleeve could be formed integrally if desired so that the plunger is provided with a portion having a diameter wide enough to provide a stop for the lower end of the conical spring.

The actuator is operated as before to move the plunger into one of the quadrants of the switch and to close the switch lever therein. Referring to FIG. 14, as the actuator moves away from center, the conical spring provides two forces which tend to return the actuator to the center off position. As the actuator moves away from center, the conical spring is tipped, i.e., one side of the cone is compressed and the other side istensioned, and the spring resists this tipping. The spring force resisting tipping increases as the actuator moves farther away from center. In addition, the conical spring is compressed, i.e., the narrow end 156 is pushed toward the wide end 155, as the plunger 52 is forced to retract upwardly on the shaft 51 as it moves up the inclined switch lever 19.

The use of the conical return spring provides several advantages over the helical spring 54 of FIGS. 1 and 2 with no increase in cost. The return force caused by the tipping of the cone is separate from the force caused by the retraction of the plunger and increases as the actuator moves away from center. With the helical spring 54, however, the rate of increase of return force decreases as the actuator moves away from center and the switch lever comes closer to being perpendicular to the longitudinal axis of the actuator. The conical return spring thus provides a greater return force, particularly at greater angles of the actuator from center, and therefore greater reset forces for preventing contact stickmg.

Another advantage of the conical spring is that the upper end of the spring bears against the casing rather than against the actuator shaft. The spring acts only on the telescoping plunger, and there is no force exerted on the actuator shaft in the longitudinal direction and no load imposed on the ball joint. The life of the ball joint is thereby extended, and the ability of the mounting ball and the O-ring to retain a seal is improved.

The conical spring uses linear space economically, and the shorter conical spring permits the outer diameter of the plunger and therefore the thickness of its cylindrical wall to be increased where the plunger extends beyond the lower end of the actuator shaft. This can be seen in FIG. 13. If the plunger 52 and sleeve 158 were made integrally, the thickness of the plunger wall would be increased by the thickness of the sleeve, and the strength of the plunger would be increased.

The conical spring has been described with specific reference to the four way, five position switch described herein in which the switch has four on positions and a center off position. However, this spring can also be used advantageously in switches heretofore available, for example, in conventional toggle switches having three positions two on positions and a center off Hermetic sealing of the interior of the casing in either embodiment is accomplished by dipping the bottom of the terminal base 21 and the tubular sleeve 45 in exposy adhesive to seal the juncture between these parts and'to embed all of the terminals on the bottom of the switch with adhesive. The major portion 43 of the switch casing may be formed of an air impermeable material such as aluminum or other metal. The only remaining point to seal is the ball and socket joint, which is sealed by the O-ring.

In the sealing process, the main body portion 43 of the casing is provided with a small hole, of about 3/32 inch diameter. This hole is connected to the port of a high vacuum system, and all of the air in the switch is evacuated. Extremely high vacuum is advantageous to remove all harmful, corrosive gases from the casing. Thereafter, a dry nitrogen gas is introduced to the interior of the switch at about atmospheric pressure. A stainless steel ball is then press fitted into the hole, and a small drop of epoxy adhesive is placed over the ball to provide an unobtrusive seal which does not extend above the surface of the casing. The hermetically sealed casing contains only nitrogen gas, which does not affect the contacts, and any moisture which could cause freezing problems is removed.

Sealing of the switch can be tested on a mass spectrometer at high vacuum by spraying the switch with helium gas. If the casing leaks, the helium will be drawn into the interior of the casing and detected by the mass spectrometer.

Although the switch provides four independent poles, each pole having a separate common terminal and two independent terminals, the structure of the switching mechanism is extremely compact. In one specific embodiment of the switch, the outside diameter of the sleeve 45 of the casing was only 0.750 inch, and this switch can easily be fitted into a conventional joy stick. If less than four poles are desired, one or more of the switch levers l9 and the associated terminals can be eliminated without affecting the operation of the remaining poles.

While I have described my switch with particular reference to use in aircraft, it will be understood that the switch can be used in many other environments. Indeed, the switch can be used in almost any application in which a multi-position, reliable switch can be used.

In the switch illustrated in the drawings the actuator is guided for movement in two perpendicularly related planes by the guide means provided by the insert 49 and the interior walls 24 of the base so that the actuator provides toggling action. It will be understood however, that other guide means could be used to permit different types of switching action. For example, the balland-socket mounted actuator could provide rotary switching action in which the lower end of the actuator could travel between any two of a plurality of switch means which were arranged in a circle within the base of the casing. The O-ring would still hermetically seal the interior of the casing by engaging the ball as it rotated, and rotary action could be obtained without rotating the knob 18 and thus any indicia means on the knob will always present the same orientation to the operator, an important consideration in many control functions.

While in the foregoing specification a detailed description of a specific embodiment of my invention was set forth for the purpose of illustration, it is to be understood that many of the details hereingiven may be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.

1 claim:

1. A multi-position electrical switch comprising a casing, a set of terminals mounted within the casing and extending outwardly therefrom, a plurality of switch levers pivotally mounted within the casing, each switch lever being pivotable between a first position in which it is out of engagement with the terminals of said set and a second position in which it engages at least one of the terminals of said set, an elongated actuator pivotally mounted within the casing and being selectively movable between a centered position and any one of a plurality of uncentered positions, each of the switch levers extending at an angle relative to the longitudinal axis of the actuator when the actuator is in the centered position and being pivotally mounted on a fulcrum positioned intermediate the ends of the lever to provide a first lever arm portion extending inwardly from the fulcrum relative to the longitudinal axis of the actuator when the actuator is in the centered position and a second lever arm portion extending outwardly from the fulcrum relative to the longitudinal axis of the actuator, the actuator comprising a plunger telescopingly mounted on an elongated shaft, a spring mounted on the actuator for urging the plunger to telescopingly extend, the plunger engaging the first lever arm portion of each switch lever when in the centered position whereby the second lever arm portion is biased away from the associated terminal of said set, the actuator being movable to move the plunger over one of the fulcrums to engage the second lever arm portion of the lever supported by said one fulcrum when the actuator is moved to each of the uncentered positions whereby the second lever arm portion of the switch lever is forced into engagement with the associated terminal of said set, movement of the actuator from the first lever arm portion to the second lever arm portion causing telescoping retraction of the plunger.

2. The switch of claim 1 in which each switch lever extends at an acute angle relative to the longitudinal axis of the actuator when the actuator engages the second lever arm portion thereof whereby the spring tends to extend the plunger and to move the plunger over the fulcrum of the switch lever toward the first lever arm portion of the switch lever.

3. The switch of claim 1 including a support terminal pivotally supporting each switch lever, each switch lever being pivotable into engagement with a pair of the terminals of said set.

4. The switch of claim 1 including a lever spring mounted within the casing for each switch lever, each lever spring biasing the associated switch lever away from the associated terminal of said set.

5. A multi-position electrical switch comprising a casing, a set of terminals mounted within the casing and extending outwardly therefrom, four switch levers pivotally mounted within the casing around the longitudinal axis thereof, each switch lever being pivotable between a first position in which it is out of engagement with the terminals of said set and a second position in which it engages at least one of the terminals of said set, an elongated actuator having a mounting ball received by a socket provided within the casing for pivotally mounting the actuator within the casing, the actuator being selectively movable between a centered position in which it is aligned with the longitudinal axis of the casing and any one of four uncentered positions in which one of the switch levers is forced into engagement with the associated terminal of said set by the actuator, and guide means on the casing for preventing movement of the actuator into more than one of the uncentered positions at a time whereby only one switch lever is forced into engagement with a terminal when the actuator is in an uncentered position.

6. The switch of claim 5 including a supporting terminal for pivotally supporting each switch lever, each switch lever being pivotable into engagement with a pair of the terminals of said set.

7. The switch of claim 5 in which each lever extends at an angle relative to the longitudinal axis of the actuator when the actuator is in the centered position and is pivotally mounted on a fulcrum positioned intermediate the ends of the lever to provide a first lever arm portion extending inwardly from the fulcrum relative to the longitudinal axis of the actuator when the actuator is in the centered position and a second lever arm portion extending outwardly from the fulcrum relative to the longitudinal axis of the actuator, one end of the actuator engaging the first l'ever arm portion of each lever when in the centered position whereby the second lever arm portion is biased away from the associated terminal, the actuator being movable over one of the fulcrums to engage the second lever arm portion of the lever supported by said one fulcrum when the actuator is moved to each of the uncentered positions whereby the second lever arm portion of the lever is forced into engagement with the associated terminal.

8. The switch of claim 5 in which the actuator comprises a plunger telescopingly mounted on an elongated shaft, movement of the actuator from the first lever arm portion to the second lever arm portion causing telescoping retraction of the plunger.

9. The switch of claim 6 including a spring mounted on the actuator for urging the plunger to telescopingly extend.

10. The switch of claim 5 including a generally conical spring surrounding the actuator and having a wide end and a narrow end, the narrow end of the spring engaging the plunger and the wide end of the spring engaging the casing between the plunger and the pivotal mounting of the actuator within the casing whereby the spring provides a return force on the actuator when the actuator is moved to one of the uncentered positions and the plunger is telescopingly retracted which tends to extend the plunger and to return the actuator to the centered position.

11. The switch of claim 5 in which the actuator comprises a plunger telescopingly mounted on an elongated shaft and a spring mounted on the actuator for urging the plunger to telescopingly extend, movement of the actuator from the first lever arm portion to the second lever arm portion causing telescoping retraction of the plunger against the bias of the spring, each lever extending at an acute angle relative to the longitudinal axis of the actuator when the actuator engages the second lever arm portion thereof whereby the spring tends to extend the plunger and to move the plunger over the fulcrum of the lever toward the first lever arm portion of the lever.

12. The switch of claim 5 in which the ball includes a pair of outwardly extending projections at generally diametrically opposed locations, the projections being slidably received in slots provided within the casing for movement in a plane passing through the longitudinal axis of the casing and parallel thereto for preventing rotation of the actuator about the longitudinal axis thereof.

13. The structure of claim 12 including an O-ring mounted within the casing below the equator of. the mounting ball and sealingly engaging the ball to hermetically seal the interior of the casing. 14. The structure of claim in which the guide means includes a wall on the casing between each adjacent pair of levers. I

15. The structure of claim 5 in which the guide means is provided by an upper portion of the casing having a generally cruciform central opening providing four recesses extending generally radially outwardly from the longitudinal axis of the casing, the actuator being selectively movable into each of the recesses. i

16. Actuating means for an electrical switch comprising-casing means provided with a'central recess, an elongated shaft extending into the central recess of the casing and having an actuated end and an actuating end, switch means engageable with the actuatingend of the shaft formovement thereby, a mounting ball on the shaft intermediate the ends of the shaft, the casing means being provided with socket means and the mounting ball being received by the socket means, and an O-ring formed of resilient material received by a recess provided in the casing means below the'equator of the ball of the shaft and sealingly engaging the ball as the ball moves within the socket.

17; The structure of claim 16 including a pair of projections extending outwardly from the ball at generally diametrically opposed locations, the casing having walls defining generally planar slots which receive the projections, the projections being engageable with the walls of the slots to prevent rotation of the ball about the longitudinal axis of the shaft but being movable within the plane of slots to permit rotation of the ball about axes perpendicular to the longitudinal axis of the shaft.

18. The structure of claim 16 in which the recess for the O-ring surrounds the ball and includes upper and lower walls which extend generally towardthe center of the ball.

19. The structure of claim 16 in which the recess is 12 provided by a groove in a portion of the casing, the groove lying in a plane generally perpendicular to the longitudinal axis of the central recess of the casing, and an annular washer secured above thegroo ve and retaining the O-ring in the groove.

20. The structure of claim 16 including guide, means on the shaft and the casing for restricting movement of the shaft in two generally perpendicular planes which extend through the longitudinal axis of the central recess and generally parallel thereto.

21. The structure of claim 16 including at least one projection extending outwardly from the ball and lying in a plane which is both perpendicular to the center line of the shaft and intersects the center of the ball.

22. In a multi-position electrical switch having a casing, a pair of terminals within the casing and extending outwardly therefrom, contact means movably mounted within the casing and being movable between a first position in which it is electrically connected to one of the terminals but not the other terminal and a second position in which it is electrically connected to bothterminals, an elongated actuator within the casing having an end engaging the contact means, means on the actuator and the casing for pivotally mounting the actuator, the actuator being pivotable between a centered position in which said end of the actuator maintains the contact means in the first positionand an uncentered position in which said end of the actuator forces the contact means'intothe second position, an improved actuator centering means comprising a generally conical spring surrounding the actuator and having a wide end and a narrow end, the narrow end engaging the actuator and the wide end engaging the casing between the narrow end and pivotal mounting means whereby the spring provides a return force on the actuator when the actuator is moved to the uncentered position which tends to second position.

' 4 l II l

Claims

7. The switch of claim 5 in which each lever extends at an angle relative to the longitudinal axis of the actuator when the actuator is in the centered position and is pivotally mounted on a fulcrum positioned intermediate the ends of the lever to provide a first lever arm portion extending inwardly from the fulcrum relative to the longitudinal axis of the actuator when the actuator is in the centered position and a second lever arm portion extending outwardly from the fulcrum relative to the longitudinal axis of the actuator, one end of the actuator engaging the first lever arm portion of each lever when in the centered position whereby the second lever arm portion is biased away from the associated terminal, the actuator being movable over one of the fulcrums to engage the second lever arm portion of the lever supported by said one fulcrum when the actuator is moved to each of the uncentered positions whereby the second lever arm portion of the lever is forced into engagement with the associated terminal.

13. The structure of claim 12 including an O-ring mounted wiThin the casing below the equator of the mounting ball and sealingly engaging the ball to hermetically seal the interior of the casing.

14. The structure of claim 5 in which the guide means includes a wall on the casing between each adjacent pair of levers.

15. The structure of claim 5 in which the guide means is provided by an upper portion of the casing having a generally cruciform central opening providing four recesses extending generally radially outwardly from the longitudinal axis of the casing, the actuator being selectively movable into each of the recesses.

16. Actuating means for an electrical switch comprising casing means provided with a central recess, an elongated shaft extending into the central recess of the casing and having an actuated end and an actuating end, switch means engageable with the actuating end of the shaft for movement thereby, a mounting ball on the shaft intermediate the ends of the shaft, the casing means being provided with socket means and the mounting ball being received by the socket means, and an O-ring formed of resilient material received by a recess provided in the casing means below the equator of the ball of the shaft and sealingly engaging the ball as the ball moves within the socket.

17. The structure of claim 16 including a pair of projections extending outwardly from the ball at generally diametrically opposed locations, the casing having walls defining generally planar slots which receive the projections, the projections being engageable with the walls of the slots to prevent rotation of the ball about the longitudinal axis of the shaft but being movable within the plane of slots to permit rotation of the ball about axes perpendicular to the longitudinal axis of the shaft.

18. The structure of claim 16 in which the recess for the O-ring surrounds the ball and includes upper and lower walls which extend generally toward the center of the ball.

19. The structure of claim 16 in which the recess is provided by a groove in a portion of the casing, the groove lying in a plane generally perpendicular to the longitudinal axis of the central recess of the casing, and an annular washer secured above the groove and retaining the O-ring in the groove.

20. The structure of claim 16 including guide means on the shaft and the casing for restricting movement of the shaft in two generally perpendicular planes which extend through the longitudinal axis of the central recess and generally parallel thereto.

22. In a multi-position electrical switch having a casing, a pair of terminals within the casing and extending outwardly therefrom, contact means movably mounted within the casing and being movable between a first position in which it is electrically connected to one of the terminals but not the other terminal and a second position in which it is electrically connected to both terminals, an elongated actuator within the casing having an end engaging the contact means, means on the actuator and the casing for pivotally mounting the actuator, the actuator being pivotable between a centered position in which said end of the actuator maintains the contact means in the first position and an uncentered position in which said end of the actuator forces the contact means into the second position, an improved actuator centering means comprising a generally conical spring surrounding the actuator and having a wide end and a narrow end, the narrow end engaging the actuator and the wide end engaging the casing between the narrow end and pivotal mounting means whereby the spring provides a return force on the actuator when the actuator is moved to the uncentered position which tends to return the actuator to the centered position.

23. The structure of claim 22 in which the actuator includes a plungEr telescopingly mounted on an elongated shaft and providing said actuator end engaging the contact means, the narrow end of the spring engaging the plunger, movement of the actuator from the centered position to the uncentered position causing the plunger to telescopingly retract as the plunger moves the contact means from the first position to the second position.