US 3641290 A
A switch for opening and closing electric circuits, the switch comprising a pivotally mounted switch arm normally disposed in switch closed position, magnet coupling means for holding said switch arm in its closed position, means exerting a biasing force on said switch arm constantly tending to urge said switch arm for movement to an open position, the coupling force exceeding the biasing force, said switch arm forming a first moment of inertia arm, and a weighted lever assembly forming a second moment of inertia arm, said weighted lever assembly being connected with the switch arm, and the switch arm being assembled in such a manner that when an inertial force from any direction added to the biasing force exceeds the coupling force, the switch arm will be caused to move from its normally closed position to its open position.
Description (OCR text may contain errors)
United States Patent Murphy et al.
[ 5] Feb. 8, 1972  VIBRATION-RESPONSIVE SWITCH  Inventors: Frank W. Murphy; Frank W. Murphy, Jr., both of 3131 S. Sheridan, Box 45248, Tulsa, Okla. 74145  Filed: Aug. 10, 1970  Appl.No.: 62,336
Primary ExaminerRobert K. Schaefer Assistant ExaminerM. Ginsburg Attorney-Kimmel, Crowell & Weaver [5 7] ABSTRACT A switch for opening and closing electric circuits, the switch comprising a pivotally mounted switch arm normally disposed in switch closed position. magnet coupling 'means for holding said switch arm in its closed position, means exerting a biasing force on said switch arm constantly tending to urge said switch arm for movement to an open position. the coupling force cxceeding the biasing force, said switch arm forming a first moment of inertia arm, and a weighted lever asembly forming a second moment of inertia arm, said weighted lever assembly being connected with the switch arm, and the switch arm being assembled in such a manner that when an inertial'force from any direction added to the biasing force exceeds the coupling force, the switch arm will be caused to move from its normally closed position to its open position.
14 Claims, 7 Drawing Figures VIBRATION-RESPONSIVE SWITCH BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to electrical circuit breakers and makers as presently classified in the United States Patent Office Manual of Classification and particularly to vibrationsensing apparatus having a switch arm releasably held in a first position by magnetic coupling means and an inertia assembly connected with the switch arm and which, when activated, effects the decoupling of the switch arm enabling it to move to a second position.
2. Description of the Prior Art Related prior art devices are found in the US. Pat. issued to William O. Munroe, No. 3,448,228 and in the U.S. Pat. No. 2,942,456 which issued to Edward V. Hardway, Jr. These inertia operated switching units and other like devices known in the art are for the most part complex in construction, lack sensitivity, and are usually most difficult to service in the field. Perhaps the greatest disadvantage of all known prior art related devices is their inherent inability to respond to forces other than those exerted in a given direction, and this constitutes an important limitation on existing systems.
SUMMARY OF THE INVENTION The present invention is directed to the provision of a vibrationor acceleration-responsive device for use with oil well pumping units, mainline and portable gas compressors, heat exhanger cooling fans in gas processing and air conditioning, and with other machinery wherein destructive motion or shock constitutes a danger, and wherein the switch becomes actuated to automatically shut down the equipment and/or signals the condition thereof. The switch of the instant invention includes a switch arm having an end pivotally mounted on suitable support means and normally held in its closed position by magnetic coupling means. The switch arm is constantly biased for movement to its open position, but the coupling force exceeds the biasing force, and in the absence of an applied third force on the switch arm, the switch arm remains in its closed position. The third force, in this instance, is a force of inertia which is applied on the switch arm in the same direction as the biasing force, and when this force added to the biasing force exceeds the coupling force, the switch arm is magnetically decoupled and under the influence of the biasing force, the switch moves to its open position. The switch arm constitutes a first moment of inertia arm responsive to accelerations in one direction, and a second moment of inertia arm comprises a lever having a weight or other mass affixed thereon and which is operatively connected with the switch arm to apply a leverage thereon in response to accelerations in all other directions, and since the switch is responsive to accelerations from all directions, it is free from specific mounting restrictions so that it may be mounted in any attitude. The magnetic coupling means is achieved by mounting a permanent magnet on the switch arm and supporting a stationary armature on suitable means in proximity to the magnet, and the sensitivity of the switch is controlled by providing means for varying an airgap between the magnet and its armature. The sensitivity of the switch is further controlled by selectively adjusting the position of the weight or mass along the longitudinal axis of its associated lever, and by adjusting the tension of spring means connected with the lever which is designed to automatically return the lever to a given position relative to the spring arm.
A further object of this invention is to provide a switch of the type to which reference has generally been made above, the switch being noncomplex in construction and assembly, inexpensive to manufacture and maintain, and which is rugged and durable in use.
Other and further objects and advantages of the instant invention will become more manifest from a consideration of the following specification when read in light of the annexed drawings.
2 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view, partly broken away, illustrating a vibration-responsive switch constructed according to this invention;
FIG. 2 is a schematic wiring diagram illustrating one application of the switch as shown in FIG. 1;
FIG. 3 is an enlarged side elevational view partly in cross section, this view being taken substantially on the vertical plane of line 3--3 of FIG. 1, looking in the direction of the arrows and illustrating in full lines the switch arm in its coupled normally closed first position and in dotted lines the switch arm in its decoupled tripped open second position; 7
FIG. 4 is a detail cross-sectional view, FIG. 4 being taken substantially on the horizontal plane of line 4-4 of FIG. 3, looking in the direction of the arrows;
FIG. 5 is a detail cross-sectional view, FIG. 5 being taken on the line 5-5 of FIG. 3, looking in the direction of the arrows;
FIG. 6 is a fragmentary perspective view with parts of the switch being removed for the purpose of clarity; and
FIG. 7 is a fragmentary detail cross-sectional view of the inertial assembly, FIG. 7 being taken substantially on the horizontal plane of line 7-7 of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more specifically to the drawings, reference numeral 10 designates, in general, a vibrationor acceleration-responsive switch constructed in accordance with the teachings of this invention. The switch 10 is seen to comprise a substantially hollow rectangular housing 12 which may be formed of any suitable material such as, for example, cast aluminum. The housing 12 comprises a pair of oppositely disposed vertically spaced top and bottom walls 14, 16, a pair of oppositely disposed longitudinally spaced end walls 18, 20, and a sidewall 22. That side of the housing 12 oppositely disposed with respect to the sidewall 22 is open. The inner comers of the housing 12 formed at the junction of the top and bottom walls 14, 16, respectively, with the end walls 18, 20, respectively, are enlarged to form arcuate bosses 24, and each boss is internally tapped as at 26 (see FIG. 3) to serve a function to be described infra.
Reference numeral 28 generally designates a housing mounting bracket which comprises an elongated substantially rectangular bight portion 30 which is superimposed against the outer side of the bottom wall 16 and is secured thereon as by conventional screws 31. The opposed ends of the bight portion 30 continue into longitudinally extending diverging flanges 32, 34 and these, in turn, terminate in offset tabs 36, 38, respectively, disposed in a common plane. The tabs 36, 38 are formed with transversely extending centrally located openings 40, 42, respectively, which are adapted to receive conventional fastening means 44 therethrough to effect connection of the housing 12 with a portion 46 of a machine or apparatus, the vibration or acceleration of which is to be sensed by the switch 10.
For the purpose of this specification it will be assumed that the housing 12 is mounted on the apparatus 46 with the bottom wall 16 extending substantially horizontally and with the sidewall 22 extending substantially vertically.
The free edges of the top and bottom walls 14, I6, respectively, and end walls 18, 20, respectively, are contained in a common plane, and superimposed against these edges is an open substantially rectangular gasket 48 formed of any suitable material and which serves as sealing means between the housing 12 and a substantially rectangular closure plate 50. The inner side of the closure plate 50 is recessed as ;at 52 to receive a transparent plate 54 therein. The closure plate 50 is releasably secured to the housing 12 as by conventional screws 56 which extend transversely therethrough and through the gasket 48 for threaded engagement within the taps 26. The closure plate 50 is also formed with an elongated substantially rectangular window opening 58 whereby visual inspection of the switch 10 through the plate 54 may be made.
The switch is disposed within the housing 12 and includes a switch support base 60 which is formed of any suitable lightweight electrically nonconducting plastic material. The base 60 includes an elongated substantially rectangular mounting block 62 integrally connected with a centrally located laterally projecting substantially rectangular platform 64. Screws 66 threadedly secure the mounting block 62 flush against the inner side of the side wall 22 with the platform 64 projecting laterally away therefrom. The platform 64 normally extends substantially parallel to the bottom wall 16. A turret 68 projects upwardly from the platform 64 and is elongated in the direction of the longitudinal axis of the platform. The turret 68 has an upper side 70 (see FIG. 3) from which upwardly project raised bosses 72, 74 adjacent each end thereof. Reference numeral 78 denotes a normally upright flange which is integrally connected with the longitudinally extending free side edge of the platform 64, the flange 78 having portions thereof projecting beyond the upper and lower sides, respectively, of its associated platform. One end of the flange 78 is integrally connected with one end of a second similar flange 80 at one end of the platform 64, and the other end of the flange 78 is integrally connected with a third similar flange 82 disposed at the other end of the platform 64. The flanges 80 and 82 flare vertically as at 80A, 80B and 82A, 823 adjacent their integral connection with the base 60 to provide reinforcement for the platform 64 (see FIGS. 3, 4 and 5). To serve a function to be described below, the flange 78 is provided with a plurality of normally upright inwardly extending notches 84, 86, 88 and 90, and a reinforcing rib 92, 94, 96 integrally formed with the flange 78 projects laterally and outwardly therefrom between each adjacent pair of the aforementioned notches.
Reference numerals 98, 100, 102 and 104 each denotes an Lshaped connector bar. Each connector bar includes a normally upright leg portion 106 having its lower end disposed within one of the aforementioned notches, and a foot section 108 which extends transversely across the platform 64 and which is received in a downwardly opening recess 110 (see FIG. 5). It will be understood that while but one such recess has been shown in the drawings, it will be understood that a similar recess will be formed to communicate, respectively, with each of the remaining notches.
Reference numerals 1 12 and 114 each denotes an L-shaped sheet metal switch standard, each of the standards including a normally upright leg portion 118 and a horizontal foot section 120. The foot sections 120 of each of the standards are superimposed on the upper side of the platform 64 with the foot section 120 of the standard 112 being aligned with the foot section 108 of the connector bar 98 and these are fixedly connected on the platform 64 and electrically connected together as by a metallic rivet 122. In a similar manner the foot section 120 of the standard 114 is superimposed against the upper side of the platform 64 in aligned relationship relative to the foot section 108 of the connector bar 100, and these foot sections are fixedly secured on the platform 64 and electrically connected together as by a rivet 124.
Reference numerals 126, 128 each denotes identically constructed L-shaped electrical connector lugs, each of the lugs including an upright leg portion 130 and a normally horizontal foot portion 132 superimposed against the upper side of the platform 64. The foot section 132 of the lug 126 is vertically aligned with the foot section 108 of the connector bar 102 and the foot section 132 of the lug 128 is vertically aligned with the foot section 108 of the connector bar 104. The last-mentioned aligned foot sections are fixedly connected on the platform 64 and are electrically connected together as by rivets 134 and 136.
At 138 is indicated a substantially Ushaped sheet metal switch standard having a bight portion 140 superimposed against the upper side of the platform 64 and secured thereto by means of a rivet 142. The opposed ends of the bight portion 140 carry upwardly projecting integrally connected arms 144, 146.
With reference-to the platform 64, the leg portions 118 of the L-shaped switch standards 112, 114, respectively, are disposed in longitudinally spaced and confronting relationship relative to one another, and the leg portion 118 of the switch standard 112 has rigidly affixed thereto a fixed switch contact 148 adjacent its upper free end, and a similar fixed switch contact 150 is fixedly connected to the leg portion 118 of the switch standard 114.
Again with reference to the platform 64 and to the several FIGS. of the drawings, it is seen that the switch standards 112 and 138 are laterally spaced from one another and that the leg portion 118 of the switch standard 112 is aligned with the arm 146, the latter having a fixed switch contact 152 fixedly connected thereto adjacent its upper end.
Reference numeral 154 denotes bracket means (see FIG. 6) having a substantially rectangular main body portion 156 superimposed against the upper side of the platform 64 and secured thereto by conventional screws 158. The bracket means 154 may be formed of any suitable metallic material and includes a pair of upwardly extending diverging arms 160, 162 which project laterally, respectively, from a pair of opposed sides of the main body portion 156, and the upper ends of the arms 160, 162 terminate in substantially vertical ears 164, 166. The ears 164, 166 support the opposed ends of a switch arm 170 having an inverted substantially T-shaped configuration. The switch arm 170 includes a crosshead 172 and an upwardly extending stern 174. The crosshead 172 includes tabs 176, 178 which are journaled for rotation on a shaft 168 in the conventional manner. Reference numerals 180, 182 each denote a lug integrally formed with the stem 174 proj ecting laterally from its opposed edges intermediate its ends. The lug has a fixed switch contact 184 fixedly secured thereon, and the lug 182 carries a pair of switch contacts 186, 188 on opposed sides thereof, respectively. The switch contacts 148, 152 are disposed in the arcuate path of movement of the switch contacts 186, 184, respectively, as the switch arm 170 turns in a counterclockwise direction, reference being had to FIG. 3 of the drawings, and the switch contact 150 is disposed in the arcuate path of movement of the switch contact 188 as the switch arm 170 pivots in its other or clockwise direction, reference again being had to FIG. 3 of the drawings.
The stem 174 includes an upwardly extending offset portion 190 which terminates in a tongue 192 which is substantially parallel to the stem 174. The stem 174 immediately adjacent its offset portion 190 is formed with a transversely extending opening 194 to serve a function to be described.
Reference numeral 196 indicates, in general, a permanent magnet of the Ushaped type, the magnet 196 including the arms 198, 200 and an interconnecting bight 202. The bight 202 is secured on the tongue 192 as by means of a screw 204 and cooperating nut 206. The function of the permanent magnet will be described below, and reference will be made also below in connection with the function of the opening 208 which extends transversely through the stem 174 adjacent the offset portion 190.
Reference numeral 210 designates, in general, a substantially U-shaped bracket having a bight portion 212 fixedly connected to the bosses 72, 74 as by the screws 214. An arm 216, 218 projects laterally and upwardly from, respectively, each end of the bight portion 212. Extending between the confronting arms 216, 218 is a temperature-compensated helicoidal spring 220 having an elongated central section 222 which terminates in end portions 224, 226 of shorter length and lesser diameter. The arm 218 is provided with an opening 228 which extends transversely therethrough and which loosely receives the shank 230 of a screw 232. The shank 230 is threadedly engaged in the spring end portion 226. The other end portion 224 of the spring 220 receives the threaded end 233 of a lever 234 (see FIG. 7), the lever 234 extending loose ly through a fitting 236 fixedly secured in the arm 216 and extending transversely through the opening 194 in the stem 174. The fitting 236 is substantially cylindrical in configuration and includes a substantially cylindrical side wall 238 which is reduced in outside diameter at one end thereof to form a neck 240 which extends through the opening 242 formed in the arm 216, the outer end of the neck 240 being peened over to form a flange 244 which securely clamps the fitting 236 on the arm 216. The neck 240 is bored at 246, and one end of the bore 246 opens into an enlarged counterbore 248 formed in the side wall 238 to provide a substantially annular seat 250 for an element of a switch actuating assembly to be described.
The switch actuating assembly includes the lever 234 and a switch arm actuator member 252. The member 252 is formed of a cylindrical plate 254 having a conical protuberance 256 projecting from one side thereof. The protuberance 256 adjacent its base end is rounded or arcuately shaped in transverse cross section as is indicated at 258. The actuator member 252 is formed with a threaded bore 259 which extends axially therethrough to receive the threaded end 233 of the lever 234 therethrough. The actuating assembly further includes an inertial mass 260 which is formed with a bore 261 which receives the other end of the lever 234 therein. The mass 260 is held in axially adjusted position on the lever 234 as by a set screw 262. A helicoidal spring 263 is mounted on the shaft 168 and has one of its ends 263a bearing against the stem 174, and its other end fixedly anchored against movement. The tension is such that the switch arm 170 is constantly biased for pivotal movement on the shaft 168 in a counterclockwise direction, reference being had to FIG. 3 of the drawings. Thus, and in FIG. 7 of the drawings, it will be seen that the stem 174 is, in the absence of any oppositely applied force, constantly biased for movement from its full line position fitting flush against the switch actuator member 252 to its dotted line position of this Figure.
Reference numeral 264 denotes an opening formed in the upper end of the arm 216. The opening 264 has one end of an elongated internally threaded sleeve 266 fixedly secured therein by conventional means, and the other end of the sleeve is provided with a diametrically extending slot 267.
Reference numeral 268 denotes a substantially flat cylindrical magnet armature which is formed with a centrally located elongated cylindrical rod 270 which projects laterally from one side thereof. The rod 270 is formed with a threaded outer end 272 that is engaged within the sleeve 266 and projects therebeyond. The projecting end 272 of the rod 270 is threadedly received within an internally threaded pocket 274 formed in one end of an elongated substantially cylindrical adjustment shaft 276. The shaft 276 is formed, preferably, of a nonmagnetic material such as, for example, any suitable plastic, and the other end thereof is provided with a diametrically extending tool blade receiving slot 278. If desired, the aforementioned other end of the shaft 276 may be encased within a substantially hollow cylindrical tool guide and keeper sleeve 280. A cotter pin releasably connects the threaded end 27 2 of the rod 270 with the adjacent end of the shaft 27 6.
The armature 268 is disposed in the arcuate path of travel of the magnet 196, and in one position of the switch arm 170 the magnet 196 becomes magnetically coupled with its armature 268 across an airgap 284, all in a manner to be described below.
The end wall is formed with an internally threaded opening 286 which is positioned, preferably, in confronting relationship relative to the slot formed in the shaft 276. The opening 286 enables the blade of an appropriate tool such as, for example, a screwdriver to be inserted therethrough for engagement within the slot 278 whereby rotation of the blade will cause the shaft 276 to turn and to turn the rod 270 about its longitudinal axis. This rotation of the rod will cause the same to shift axially within the sleeve 266 and to thereby move the armature towards and away from the magnet 196 when the latter is in the confronting relationship shown in the several Figures of the drawings whereby the operator may adjust the width of the air gap 284. The opening 286 may be closed when not in use as by any suitable plug 288.
Switch reset means 290 is provided for the switch 10, the reset means including an externally threaded elongated sleeve 292 which is extended through a suitable opening 294 formed in the end wall 18. The hollow sleeve 292 is provided with a cylindrical flange 296 at one of its ends and which bears against the inner side of the wall 18. The other end of the sleeve 292 extends through an instruction plate 298 and the sleeve is secured on the wall as by means of a nut 300.
Reference numeral 302 denotes a plunger rod assembly including a plunger rod 304 mounted for reciprocation in the sleeve 292 and through an opening 306 formed in the flange 296. The outer end of the rod 304 terminates in an enlarged cylindrical head 308 which slidably engages within the sleeve 292. Engaged around the rod 304 is a helicoidal spring 310 having one of its ends engaging against a central portion of the flange 296 and its other end abutting the adjacent side of the head 308. The rod 304 is, thus, constantly biased for movement to the left as viewed in FIG. 3 of the drawings, and movement in this direction is limited by the integrally formed limit flange 309. The inner end of the rod 304 is disposed in the arcuate path of movement of the stern 174 adjacent the lower end thereof. Normally, the inner terminal end of the rod 304 is spaced from the stem 174 when the switch arm is in its magnetically coupled full line position shown in FIG. 3, and only becomes engageable therewith upon the decoupling of the magnet 196 from its armature 268 in a manner to be described below.
If desired, the normally exposed outer end portion of the head 308 may be enclosed withing a moisture proof cap 312 having a socket 314 formed in the end wall 316 to receive the outer end of the head 308 therein. As is seen in FIG. 3 of the drawings, the end wall 316 is integrally connected with a cylindrical side wall 318 having an inwardly turned annular flange 320 releasably engageable within an annular groove 322 formed in the nut 300. The cap 312 may be formed of any suitable waterproof, dustproof and flexible material, and need not be removed to effect the operation of the rod 304.
The end wall 20 adjacent the bottom wall 16 is formed with an internally threaded opening 324 which threadedly receives a substantially hollow nipple 326 through which lead wires or a wire cable may be extended for connection to selected ones of the connector bars 98, 100, 102, 104. The wires may be soldered to the appropriate connector bar or, if preferred, such wires may be secured thereon as by screws (not shown) which are threaded in openings 330 formed in the upper end of each of the leg portions 106.
Having described in detail the component elements of this invention, the operation of the switch will be now set forth.
With the switch assembled in the manner described above, two factory adjustments are first made to ensure the positive operation of the switch 10 in response to a predetermined vibration, acceleration or shock force imposed thereon. These adjustments need not be made in the order recited, but the same are of importance if the sensitivity of the switch 10 is to be maintained.
First, it will be observed that the longitudinal axis of the lever 234 and that of the switch actuating member 252 are coincident so that this common axis passes through the apex of the conical protuberance 256. This axis also preferably coincides with the axis of the bore 246 and of the counterbore 248. The conical protuberance 256 is seated on the annular seat 250, each making a 360 contact with the other. The cylindrical plate 254 fits flush against the outer end of the side wall 238 of the fitting 236. This alignment is maintained by adjustment of the screw 232 to place the spring 220 under proper tension in accordance with the weight of the inertia mass 260 and its adjusted position axially with respect to the lever 234. The screw 232, as shown in FIG. 3, hasa head bearing against the arm 218. Therefore the rotation of the screw will cause the spring end portion 226, which is threaded onto the screw shank 230, to shift axially to effect the tension adjustment of the spring 220. It is preferable that the longitudinal axis of the spring 220 coincide with the common longitudinal axis of the lever 234 and the actuator member 252. In the normally closed position of the switch 10, the stem 174 of the switch arm 170 will be flush against the adjacent side of the plate 254. The positions of these several elements as defined above are clearly shown in FIGS. 3, 4 and 7 It will now be clear from a consideration of FIGS. 6 and 7 that as the free end of the lever 234 swings under an inertial force in the directions of the vector arrows A, B, or in the directions of vectors which include a combination of each of the vector forces A, B in response to a force not parallel to the longitudinal coincident axes of the lever 234 and actuator member 252, the conical protuberance 256 will pivot on its seat 250 and will tend to move outwardly therefrom to cause the plate 254 to rock on a point of the adjacent end of the sidewall 238 disposed in the path of the force, and this causes a diametrically opposite portion of the plate 254 to tilt away from the adjacent end of the side wall 238 and applies a leverage force on an adjacent portion of the stem 174. If when the sum of the applied force and the biasing force exceeds the magnetic coupling force, the switch arm 170 becomes decoupled and trips for snap turning movement of the switch arm 170 to its open second position.
When the switch arm 170 is moved to its open position, it will remain in this position until it is reset. Resetting is accomplished by exerting a force on the head 316 causing the plunger rod 304 to push against the stem 174 to cause the switch arm 170 to pivot from its dotted line position of FIG. 3 to its closed full line position illustrated in that Figure. The release of the head 308 will cause the plunger rod 304 to move to the left under the influence of the spring 310 until the limit flange 309 engages against the flange 296.
As the switch arm 170 returns to its normally closed first position, the spring 220 draws on the lever 234 causing the protuberance 256 to again seat on its annular seat 250 and the components of this moment of inertia arm become realigned. The moment of inertia of this arm may be adjusted by sliding the weight or mass 260 in the direction of the longitudinal axis of the lever 234 and releasably securing the same thereon in its adjusted position by means of the set screw 262. The moment of inertia of this system can also be further adjusted by the screw 232.
A further factory adjustment comprises an adjustment of a second moment of inertia arm which includes the switch arm 170 and its connected magnet 196. This adjustment involves moving the armature 268 relative to the permanent magnet 196 to vary the width of the air gap 284. The coupling force becomes weaker, of course, as the airgap 284 is widened. This adjustment is essential in order that the switch be made sensitive to forces acting in the direction of the longitudinal axis of the lever 234. The adjustment is made so that the force of inertia of the last named moment of inertia arm when added to the biasing force of the spring 263 exceeds the force of the magnetic couple, the switch arm 170 will pivot away from its full line position of FIG. 3 and will continue to its dotted line position shown in this Figure under the influence of the spring 263. The switch 10 may be afterwards reset in the manner described above.
Summarizing the operation of the switch 10, it will be understood that the conical protuberance 256 is so shaped as to centralize the longitudinal axis of the switch actuator member 252 and to make the same coincident with the axis of the fitting 236 so that the cylindrical plate 254 seats on the adjacent end of the side wall 238 and is flush against the adjacent side of the stem 174. The plate 254 can rock on the adjacent end of the sidewall 238 as a consequence of a force of inertia imposed on the moment of inertia arm 170, 196 in response to an acceleration force in the direction of the longitudinal axis of the lever 234, but these elements are normally held in alignment by the tension provided by the spring 220. The inertial mass 260 which is connected on the free end of the rod 234 is adjustable in order that the moment of inertia of this arm may be varied in accordance with given requirements. These features, taken together with the spring tension adjustment afforded by the screw 232, allows a considerable range of ad-' justable control of the stability or sensitivity of the system or switch to acceleration components exercised on the lastdefined moment of inertia arm in all directions except those occurring along the coincident axes of the lever 234, switch actuator 252 and tension spring 220.
The switch arm 170 is hinged or pivotally mounted on the platform 64 and is biased for movement to its open position by the spring 263. The switch arm 170 and the mass of its magnet 196 comprise a moment of inertia arm to which reference has been made above. In its closed position, the switch arm 170 is held stable and flush against the plate 254 of the switch actuator 252 by the magnetic coupling provided by the permanent magnet 196 and its armature 268. The air gap284 is adjusted by means which includes the internally threaded sleeve 266,
the rod 270 and its threaded end 272, and the manually operable connected shaft 276, all of thesev cooperating to provide a main externally operable sensitivity adjustment.
The combined mass of the switch arm 170 and magnet 196 connected on the free end thereof constitute a moment of inertia arm responsive to an acceleration force occurring in the direction of the coincident axes of the lever 234 and switch actuating member 252. Vector acceleration in the direction of the planes of the arrows A and B introduces moments of force in the moment of inertia arm which includes the weight 260, the lever 234 and the switch actuating arm 252 which operate the switch arm 170 as described above. Vector acceleration in planes other than those confined to the planes of the arrows A and B and which are not directly in line with the coincident axes of the last-mentioned moment of inertia arm may, by use of vector analysis, be divided into components which act on both moment of inertia arms systcms simultaneously and with the same end effect as the vector acceleration would promote were it to be applied along an axis of major freedom of one momentof inertia arm system which is the neutral axis of the other moment of inertia arm system.
With this arrangement of two mutually perpendicular inertially responsive systems, the overall switch device is adjustably responsive to vibration accelerations in any plane and does not require special orientation or mounting attitude as is the case with most other similar devices. FIG. 1 of the drawings is to be understood as illustrating one mounting attitude and in the specification, references to horizontal," vertical," and upright and similar words and expressions have been used merely for the purpose of orienting one element relative to the others and are not intended to comprise specific limitations.
FIG. 2 schematically illustrates components of the switch 10 connected in a conventional typical ignition system for an internal combustion engine.
In the schematic wiring diagram of FIG. 2 a battery 400 has its negative side grounded at at G by wire 402. The positive side of the battery 400 connects to one side of an ammeter 404 by wire 406, and the other side of the ammeter 404 connects by wire 408 to one side of a'normally closed ignition switch 410. The other side of the ignition switch connects by wire 412 with the connector bar 100. One end of a wire 414 is connected with the connector bar 102 (see FIG. 4), and the other end of the wire is extended to the opening 208 (see FIG. 5) formed in the stem 174 of the switch arm 170, and this end of the wire 414 is then soldered or otherwise secured therein. Wire 416 has one of its ends connected with the bar 102 and its other end with one side of a conventional ignition coil 418. The ignition coil 418 connects with the usual distributor 420 via wires 422 and 424.
Now with the switch 10 in its normal operating condition and the engine (not shown) running, the switch arm 170 will be in its upright full line position as shown in FIG. 3. In this position, the switch contact 188 is engaged with the switch contact and current flows through the wire 416 to the ignition coil 418. I
Now as the switch arm pivots counterclockwise from its full line position of FIG. 3 to its dotted line position as shown therein, the contacts 150, 186 will separate to cut off the flow of electrical current through the wire 416 thereby halting the operation of the engine.
If desired, one side of an alarm system (not shown) could be connected to the bar 98 and its other side connected to the positive terminal of the battery 400 or to the wire 406. Such a system would become energized upon the moving of the switch arm from its normally closed full line position of FIG. 3 to its dotted-line position shown therein. Under this condition, contacts 152, 154 and 148, 186 would close against one another thereby establishing an electric circuit running through the wire 406 and through the system and its wire connection to the bar 98, through the closed contacts 148, 186 across the switch arm 170, across the closed switch contacts 184, 152, the arm 144 and wire 428 (see FIGS. 2 and 4), the latter being grounded.
The wire leads for connection to equipment located externally of the housing 12 may be led into the housing through the nipple 326. If alarm means is not connected with the switch 10, the condition of the switch may be determined by visual inspection thereof through the window 58.
When the switch arm 170 moves from its normally closed position shown in full lines in FIG. 3, it may actuate the simple electrical contacts referred to above, snap switches, pneumatic or fluidic switches, or electronic capacitance or inductive switching devices. The closing or resetting of the switch may be readily accomplished by the manually operable means referred to above, or by remotely controlled electrical solenoid, pneumatic or fluid actuators, also remotely controlled.
Having described and illustrated one embodiment of this in vention in detail, it will be understood that the same is offered merely by way of example, and that this invention is to be limited only by the scope of the appended claims.
What is claimed is:
l. A vibration responsive switch for closing and opening an electric circuit, said switch comprising:
a switch amt;
means pivotally connecting one end of said switch arm on said support means, said switch arm having a free end pivotable about the pivotal axis of said switch arm between a switch normally closed inner position and a switch open outer position;
means exerting a biasing force on said switch arm to constantly urge said switch arm to pivot from said closed inner position to said open outer position;
magnet means on said free end of said switch arm;
a magnet armature mounted on said support means and disposed in an extension of the arcuate path of travel of said magnet means as said switch arm pivots towards its inner position;
said magnet means and said magnet armature cooperating to provide magnetic coupling means having a coupling force greater than said biasing force to releasably hold said switch arm in its inner position;
a lever extending transversely of said pivotal axis and through said switch arm;
an inertial weight secured to the outer end of the lever;
a plate secured to the lever inwardly of the switch arm; and
means so seating the plate to the support means as to enable at least a portion of the plate to move outwardly of the support means in response to the application of a force to the lever to thereby pivot the switch arm outwardly until said biasing force exceeds said coupling force so that the biasing force can move the switch arm to said outer position.
2. A switch as defined in claim 1 wherein:
said magnetic coupling means includes an airgap between said magnet means and said magnet armature; and
means for adjusting the width of said air gap to vary the strength of said coupling force.
3. A switch as defined in claim 1 further comprising: resilient means, connected to the inner end of the lever, yieldably urging the plate against the support means.
4. A switch as defined in claim 3 further comprising: means connected with said resilient means to adjust the tension thereof.
5. A switch as defined in claim 1 further comprising: means for securing the weight in an adjusted position on the outer end of the lever.
6. A switch as defined in claim 1 and:
means on said support means engageable with said switch arm and being operable to pivot said switch arm from its said open outer position to its said closed inner position.
7. A switch as defined in claim 1 and:
a first switch contact mounted on said switch arm for pivotal movement therewith;
a fixed second switch contact mounted on said support means and being disposed in an extension of the path of travel of said switch arm, said second switch contact being engageable by said first switch contact as said switch arm pivots to its normally closed inner position; and
means for connecting said contacts in an electric circuit.
8. A switch as defined in claim 1 wherein:
said support means comprises a platform formed of a dielectric material;
said switch arm is formed of an electrically conducting material;
a first switch contact mounted on said switch arm for pivotal movement therewith;
a fixed second switch contact mounted on said support means and being disposed in an extension of the path of travel of said switch arm, said second switch contact being engageable by said first switch contact as said switch arm pivots to its said normally closed inner position; and
means for connecting said contacts inan electric circuit.
9. A switch as defined in claim 1 wherein said means seating the plate to the support means comprises:
a fitting on said support means, through which the lever extends, having an outwardly directed annular seat;
an inwardly directed conical protuberance on said plate;
resilient means connected to the inner end of said lever and to said support means for yieldably urging the protuberance against the seat with the protuberance making engagement with the seat throughout an arc of 360.
10. A switch as defined in claim 9 wherein:
the longitudinal axis of said lever and the axis of said conical protuberance are coincident; and A means for adjusting the tension of said resilient means for varying the moment of inertia of said lever.
11. A switch as defined in claim 9 and:
means for securing said weight in an adjusted position on said lever to selectively vary the moment of inertia thereof.
12. A switch as defined in claim 11 wherein:
said magnetic coupling means includes an airgap between said magnet means and said magnet armature; and
means for selectively adjusting the width of said airgap for selectively varying the moment of inertia of said switch arm.
13. A switch as defined in claim 12 and:
reciprocable means mounted on said support means, said reciprocable means in one direction of its movement engaging said switch arm when said switch arrn is in its said open outer position and forcing said switch arm to pivot towards its said closed inner position, and means for moving said reciprocable means in its other direction.
14. A switch as defined in claim 9 wherein said magnetic coupling means includes an air gap between said magnet means and said magnet armature and further comprising:
means for adjusting the tension of said resilient means;