US 3673362 A
This invention relates to an omni-directional intermittent, normally open electric impact switch having two hollow hemispherical terminal means which are circumambient to and insulated from a weighted helical spherically shaped spring which acts as the pole piece of the switch. A non-conducting fluid retained within a volume formed by the two hemispherical terminals dampens the movement of the weighted spring pole piece. The switch becomes operational when an impact causes one or more turns of the helical weighted spring pole to deflect and contact the inner walls of the spherical terminal.
Description (OCR text may contain errors)
United States Patent Carlson et al.
 June 27, 1972 [541 ELECTRIC IMPACT SWITCH  lnventors: Robert J. Carlson, Somerville; Royal A.
Reyrnann, Jr., Wharton, both of NJ.
 Assignee: The Unlted States at America as represented by the Secretary of the Army  Filed: May 14,1971
[2|] Appl.No.: 143,374
52 us. Cl. ..200/61.45 a s1 ..H01h3$/14 [581 rum of swell ..340/261, 262-, 200/6! .45 R,
 Relerences Cited UNITED STATES PATENTS 3,492,450 l/l970 Stockdale et al ..200/6l .45 R 3,l6l,736 l2/l964 Randal et al. ..200/6l.45 R
2,999,l79 9/l96l Bianchi et al. ..340/26l UX 2,881,276 4/1959 Mintzetal......................200l61.45 R
Primary Examiner-Robert K. Schaet'er Assistant Examiner-M. Ginsburg Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Bet] and Ernest F. Weinberger ABSTRACT This invention relates to an omnidirectional intermittent, normally open electric impact switch having two hollow hemispherical terminal means which are circumsmbient to and insulated from a weighted helical spherically shaped spring which acts as the pole piece of the switch. A non-conducting fluid retained within a volume formed by the two hemispherical terminals dampens the movement of the weighted spring pole piece. The switch becomes operational when an impact causes one or more turns of the helical weighted spring pole to deflect and contact the inner walls of the spherical terminal.
7 Claims, 5 Drawing Figures PATENTEDJUMN I972 SHEET 10F 2 FIG. I
INVENTORS ROBERT J. CARLSON R OYAL A. REYMANN JR.
ELECTRIC IMPACT SWITCH The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.
BACKGROUND OF THE INVENTION Various means are known for making anti-disturbance and electrical impact switches. Some of the prior art devices utilize the vibratory characteristics of a cantilever member supporting a mass to effect closure of the switch contacts. Other devices use the free roll motion of a ball to hit a post or posts to close the switch contact when the device is inadvertently moved. Another form of the prior art device uses the low friction roll motion of a ball in a channel to effect closure of two electrical contacts. All of the prior art devices suffer from the disability of failing to combine uniform omni-directional response to an impacting force with multi-contact switching and small size. The cantilever impact switch generally lacks the ability to respond uniformly to forces applied parallel in direction to the cantilever member. The impact switch which utilizes the free rolling ball and post while good for uniform response to omni-directional applied forces, fails to perform satisfactorily in low voltage applications because of the unreliability of single point contact when either the ball or the post becomes oxidized. Generally in low voltage applications a slight oxide in the area of the single point contact is sufficient to make the connection uncertain. The ball and channel type impact switches generally suffer from the lack of uniform response to omni-directional impacts.
Prior art devices are generally less satisfactory than the present invention because of their larger size, lack of sensitivity to small impacts or shocks, and unreliable under light impact where oxidized single point contacts devices do not close sufficiently or close through a high resistance path.
The present invention provides a means for reliable electrical switching which is responsive to omni-directional impacts or sudden movement of the device to which the switch is attached.
SUMMARY OF THE INVENTION The present invention relates to an electric impact switch which is responsive to impact in any plane and will provide one or more closures of electrical contacts as a result of such impact or movement.
In accordance with the present invention a metal case consisting of a pair of hemispherical terminals are assembled together so as to insure electrical continuity between the two hemispheres. The spheres can be made as small as one-quarter inch in diameter. A pair of insulator sleeves are radially and oppositely positioned and held within the walls of the hemisphere by a sealant. A spherically shaped spring having a pair of oppositely disposed and radially aligned legs passes through the insulator and is held firmly therein by a sealant. The spring legs are positioned so that the outer surface of the spherical turns of the spring lie in close proximity, but not touching, the inner walls of the sphere. A ball shaped inertial mass is located within the cage formed by the spring. A non-conducting fluid fills the remaining volume of the sphere and provides dampening for the suspended mass in the spring cage and dampening for the spring. The outside surface of the sphere case acts as one terminal of an intermittent normally open single pole switch; the ball spring with its centrally supported mass acts as the pole of the switch. Improved reliability of contact closure can be obtained in this switch over prior art devices since several coils of the ball spring will contact the case thereby assuring a positive current flow during the time of closure. The line contact that is created between the spring coils and the inside surface of the sphere, when the former touches the latter on impact, assures a more positive switching over the point contacting prior art devices. In alternate design a flat annular ring shaped insulator electrically and mechanically separates the two hemispheres. Each of the separated halves, which are electrically isolated from each other, have electrical connections attached thereto; these separate halves become the intermittent, normally open, terminals for a single pole double throw impact switch, as in the aforementioned device the spring acts as a pole of the switch. The sensitivity of the switch to a given impact can be varied by changing the diameter of the spring wire, the weight of the inertial ball, the shape of the spring thereby varying the space between the spring and the inner walls of the case, and the viscosity of the non-conducting fluid.
One of the objects of this invention is to provide an omnidirectional impact switch which is small in size.
Another object of this invention is to provide an omnidirectional impact switch whose sensitivity to impact or shock can be more readily varied without changing the outside physical dimensions of the switch.
Another object of the invention is to provide an improved omni-directional, intermittent, normally opened, single-pole single throw impact switch which has a more reliable contact surface.
Another object of the present device is to provide an intermittent, normally opened, omni-directional, single-pole double throw impact switch which is sensitive to small impacts or shocks.
For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross-sectional view of the impact switch in the single-pole single throw configuration.
FIG. 2 is a plan view of FIG. 1 taken in the direction of line 2-2.
FIG. 3 is a partial sectional view of FIG. 2 taken along line 3-3 to show the shape of the two flanges, the insulator sleeve, and the location of one of the spring legs.
FIG. is a partial cross-sectional view of an omnidirectional, intermittent, normally open, single-pole double throw impact switch.
FIG. 5 is a partial cross-sectional view through line 5-5 of the hemisphere halves and insulator as illustrated in FIG. 4.
Throughout the following description like reference numerals are used to denote like parts in the drawing.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is concerned with a device which will reliably effect the closure of an electrical circuit when the device is subject to an omni-directional impact. In its broader aspects it is intended to cover the switching of an electrical circuit which is responsive to an omni-directional impact of a specific minimum impact force and non-responsive to an impact force of lesser value.
Referring now to FIG. 1, the two conductive hemisphere terminal covers 10 and [2, provided with outwardly circumferential flange, are mechanically and electrically held together so that they are leak tight and exist at the same electrical potential. A spherical helix shaped pole spring 14 is located and held within the two terminal covers 10 and 11 by a pair of insulator sleeves l6 and 16'. The pole spring legs 20 and 20' are firmly affixed to the insulators l6 and 16 by a lead and leg sealant l8 and 18'. The sleeve insulators each have one chamfered end face I! and 17' fixedly attached to the insulator cover sealing flanges 26 and 26' by an insulator flange sealant 30 and 30'. Sealants similar to I8, 18', 30 and 30 may be obtained from Hysol Div., Dexter Corp., 2] l Franklin St., Olean, NY. 14760 as Hysol Epoxy Kit 1C. The lead and leg sealants l8, l8 and insulator sealants 30. 30' prevent the now conducting fluid 22, which fills the inclosed volume between the two hemisphere terminal covers I0 and II from escaping. The non-electrically conducting fluid 22 will dampen the spring oscillation after an impact is delivered to the switch. The viscosity of the fluid can be varied to obtain the degree of dampening and sensitivity desired. The non-conducting fluid 22 is available from American Oil & Supply Co., 239 Wilson Ave, Newark, NJ. as transformer oil. An inertial ball 32 is located inside of the helix of the spherical pole spring 14. Upon impact the ball 32 is free to exert a force against the pole spring I4 causing it to deflect and touch the inner walls 11 and ll of the terminal covers and 12 thereby effecting closure of an electrical conductive path between the pole spring leg 20 and terminal lead 24. Lead 24 is fixedly attached to the first hemispherical cover 10 by a solder connection 28.
FIG. 2 which shows a plan view of FIG. 1 taken along line 2-2 illustrates the spherical shape of the hemisphere terminal cover 10 and the peripheral position of the cover sealing flange 25.
FIG. 3 which is a cross-sectional view taken along line 3-3 of FIG. 2 illustrates how the insulator cover sealing flanges 26 and 26' have oppositely disposed contoured grooves 23 and 23' which surround and hold the insulator 16. In a similar manner sealing flanges 27 and 27' (not shown in FIG. 3) hold insulator 16' (not shown in FIG. 3).
As will be noted, FIG. 4 is a modification of FIG. 1 showing an omni-directional, intermittent, normally open, single-pole double throw switch. Two hemispherical shaped covers 40 and 42 have peripheral integrally attached flat flanges 46 and 46' respectively. An annular, ring shaped, insulator 44 is sealed to flat flanges 46 and 46' by insulator to flange sealant 31 and 3| at the insulator flat faces 21 and 23 respectively.
A pair of radially oppositely disposed holes l9, 19 in the annular insulator 44 permits the central positioning of a helical spherically shaped spring 14 within the inclosed cavity formed by the hemisphere halves 40, 42 and insulator 44 so that the spring 14 is electrically isolated from the halves 40, 42 when the device is in a quiescent state. A lead sealant 18, 18' holds the spring legs 20 and 20 firmly affixed to the insulator 44 and prevents the escape of a non-conducting fluid 22 which fills the inclosed cavity. A ball weight 32 is inclosed within the spring in a similar fashion aforementioned in referring to FIG. I. A pair of leads 24, 24' are attached to hemisphere terminal halves 40, 42 by lead solder 28, 28' respectively. The hemisphere halves 40, 42 act as the contact terminals of the inter mittent normally open single pole-double throw switch; the extended end of spring leg 20 provides a connection to the pole element 14.
As can be seen FIG. 5 shows annular insulator 44 in contact with the inner walls 47, 47' of flat flanges 46 and 46 respectively. A radial hole 19 in insulator 44 is centrally located with respect to flanges 46 and 46 electrically isolating lead 20 from the flanges 46 and 46'. A lead sealant 18 holds the lead firmly affixed to the insulator 44. In a similar manner lead 20' (not shown) is positioned and held by a lead sealant 18'.
We wish it to be understood that we do not desire to be limited to the exact detail of construction shown and described for obvious modification will occur to a person skilled in the art.
What is claimed is:
I. An omni-directional electric impact switch which comprises:
a hollow terminal means;
a compliant pole means;
an insulating means for positioning said pole means within said terminal means;
an inertial mass located within said pole means responsively moves with respect to omni-directional inertial forces applied to said switch, exerting a force against said pole means, thereby causing said pole means to be displaced and to contact said terminal means at one or more points. a non-conducting fluid, filling said terminal means, having a viscosity which provides dampening for said pole means and said inertial mass; and
a sealant fixedly positions said pole means within said insulating means, and fixedly positions said insulating means within said terminal means so that said non-conducting fluid will be retained in said terminal means. 2. An electric switch as recited in claim 1 wherein said hollow terminal means forms the terminal of an intermittent, nor mally open, single pole single throw impact switch and which comprises:
a pair of hemispherical terminals having mating flanges peripherally attached to the outermost circumference of said hemispheres, said mating flanges each having two radially disposed semi-cylindrical contoured grooves, said grooves oppositely positioned to form a cylinder for holding said insulating means therein, said pair of terminals mechanically and electrically connected together forming an hermetically sealed volume for said inclosed non-conducting fluid, compliant pole means, and inertial mass.
3. An electric switch as recited in claim 2 wherein said compliant pole means comprises:
a helical spherically shaped central spring section having an axially aligned, oppositely disposed spring lead and spring leg extentions, said spring lead and said spring leg fixedly attached to said insulating means by said sealant.
4. An electric switch as recited in claim 3 wherein said insulating means comprises:
a pair of cylindrical insulators having central axially aligned holes therein for holding said compliant pole means spring lead and spring leg with said sealant, an outer cylindrical surface slidably engages said oppositely positioned semi-cylindrical contoured grooves formed by said mating terminal flange grooves, an end face of said cylindrical insulators having a chamfered surface for allowing said sealant to hermetically seal said insulators to said terminal grooves.
5. An electric switch as recited in claim 1 wherein said hollow terminal means forms the terminals of an intermittent, normally opened, single pole double throw impact switch and which comprises:
a pair of hemispherical terminals having flanges peripherally attached to the outermost circumference of said hemispheres, said flanges having a flat surface, and wherein said flanges are separated by said insulating means, said hemispherical surface having a first contact lead soldered to the outer surface of one of said terminal halves and a second contact lead soldered to the outer surface of said other terminal half.
6. An electric switch as recited in claim 5 wherein said compliant pole means comprises:
a helical spherically shaped central spring section having an axially aligned oppositely disposed spring lead and spring leg extentions integrally attached to each end of said helix fixedly attached to said insulating means by said sealant.
7. An electric switch as recited in claim 6 wherein said insulating means further comprises:
a cylindrical insulator having a central bore, a pair of flat faces perpendicular with respect to the longitudinal axis of said insulator and parallel with respect to each other, a cylinder wall perpendicular to said flat faces, said cylinder wall having a pair of radial oppositely disposed holes therethrough equally positioned midway between said flat faces fixedly, holding therein by said sealant said compliant pole means, said hemispherical terminals each forming one terminal of said double throw single pole switch.