US3001039A - Omni-directional inertial switch - Google Patents

Description

Sept. 19, 1961 A. E. JOHNSON 3,001,039

OMNI-DIRECTIONAL INERTIAL SWITCH Filed Dec. 30, 1959 FIGJA. 26 2 L .3

FIG.2. H I? $304M 5 27 BY AORNEYS INVENTOR 42 a ARTHUR E. JOHNSON Unite The invention described herein may be manufactured and used by or for the Government of the United 'States of America for governmental purposes without the payment of any royalties-thereon or therefor.

This invention relates generaly to a switching device and more particularly to an omni-directiona'l inertial switch, i.e., a switch which is responsive to acceleration in any direction. a

'More specifically, this invention contemplates a single pole switch containing a plurality of resilient linger con- .tacts, the movement of which is controlled ultimately by the intensity and direction of a sudden acceleration or force applied thereto. The fingers are normally held ,in position by resilient retaining springs and 1a conducting shaft. The springs and the fingers normally maintain a number of inertial members in predetermined initial positions. If the container should suddenly accelerate ondecelerate the contact fingers may be actuated selecfively by at least one at the inertial members, engaging the inner surface of the conductive outer shell of the container. typeof switch .is particularlysuitable for use. as an impact ,detonatorin a .tuze oar missile. .It is not intended, however, to limit the utility to], any pan -tioular type device.

Accordingly, an object of this inventionjis to providea new and improved typeofinertia:switch.

* Another object of this invention is to provide a new and improved omnidirectional inertial switch.

Other objects and many of the attendant advantages of this invention will become apparent frorn the following detailed description when consideredin connection with the accompanying drawings wherein:

gates Ptent 2 caps by means of resilient springs 21 and '22, respectively. ' Inner spring seats 15, 16 are maintained at a predetermined position with respect "to the longitudinal axis by retaining rings 33 and 34, respectively, and collar 1'9 of shaft 1 4. Conductive finger contacts 23, 24 and 25,.

26 are fixed to outer spring seats 17 and 18 respectively, by some suitable means. As shown on FIG. 2, there .arepreferably eight such fingers, four mounted on each outer spring seat, however, any suitable number may be employed. An annular inertial member 27 is supported by the finger contacts so that its inner circumference is. normally maintained equidistant from collar 19. The longitudinal movement of member 27 is restrained by inner spring seats 1 5, 16. Thus, the switch comprises three inertial members, spring seats 17, 18 as we'll as annular member 27. Members 17 and 18 are responsive to components or force suddenly applied along the longitudinal axis, while annular member 27 is responsive to components of force suddenly applied perpendicular to the longitudinal axis. Terminal 28, attached to conductive s'hatt l4 and outer shell 11 are adapted tcibe connected to any suitable conductors. A suitable terminal post maybe mounted on shell ll. When the switch is in the position illustrated in FIG. la, it is apparent that no electrical current path exists between terminal 213 and conductive shell 1i.

FIG. '11; illustrates the position of the finger contacts of the switch immediately after a force in the direction FIG. 1a illustrates a sectional view ofaswitchof the present invention in its normalposition;

FIG. lb illustrates the switch in its closed position immediately after it has suddenly been accelerated in aa direction parallel to its axis 10 illustrates the switch in :its closed position immediately after it has sheen suddenly accelerated :in a direction perpendicular -to its axis;

FIG. 1d illustrates the switch in "its closed :position immediately after it has suddenly theen accelerated in a direction sneither, parallel nor perpendicular to its taxis;

rneans. The end caps or rings 12, 13 are made of some appropriate typezofiinsrilatnr, such :as plastic. 'Gonducting shalt or rod like element 14.runs the length of the enclosure and is maintained parallel to and concentric with thetshll 1-1ibyretaining'fingsiil; 132,135 and 13.6 andby 'holeslocated in "the center of the end caps. "The shaft 14 thus forms the longitudinal axis ofthe switch container. Outer spring seats 17, 18 are designed to slide along shaft 14 but are normally retained against the end indicated by arrow .29 has been suddenly applied thereto. Outer spring seat orinertial member 17 is moved toward inner spring seat 16 compressing spring 21 and causing conductive finger contacts 23, 24 to engage the inner contact surface of conductive shell 11, 11. Thus, aconnection is made between terminal '28 and the inner surface on conductive shellby way of shaft I land fingers I23, .24. path is opened as soon as the suddenly applied force is removed due to the resilient action of spring '21. Spring .22 spring seat 18 and inertial member 27 are not afiectedby suddenaccelerations in the directionfindicated by arrow 2% and accordingly the positions of contact fingers 25 and 26 are maintained substantially constant. If a Jforce is suddenly applied in the opposite direction, contacts 23 and .24 will remain stationary, while con- .tacts25 and .26 will engage the conductive shell.

FIG. 1c illustrates the position of the finger contacts immediately after asudden acceleration or force .is applied to the switch in the direction indicated by arrow 37. Such a ,force causes inertial member 27 to slide along .co'llar19 as shown .andresults .in .at leastone-of the contact fingers 23, 2 25, or 26 engaging shell .11, .fingerf24being so illustrated. -.Since there isno movement of the springs .21, '22 or of the spring seats, .there will be noChangeIinflOngitudinal position of any of the contact fingers. .If .the enclosure .is suddenly accelerated in a direction opposite to that indicatedlby arrow 37, or is suddenly decelerated in the direction of arrow 31, his apparent that @contact would be made'by-finger 2'3 withthat portion of .the shell designated 1 1 in .lieu of finger .24 engaging shell per tionlil.

fFIG. 21d illustrates .the position of the finger contacts when sudden acceleration in the direction indicated by arrow .38 'isoccurring. Such .a force causes inertial mem- "ber27 to slide along collar 19 as indicated. .Also spring seat 1'7 partially compresses spring 21. vTheresultant forces produced by seat v1'7 and inertial .member27 :causes contact finger Zeinto engagement withsshell .11. i

' IFIG. 2 Iis.a.completesectional view ofztheswitch rinrits normally open position taken along the line 2--2 of FIG. la. with respect to shell 11, inertial member 27 and central shaft "14 is illustrated therein. Contact fingers 23, 24, 41

The true relationship of the contact fingers I and 42 are mounted on spring seat 17 in quadrature relationship while fingers 25, 26, 43 and 44 are mounted on spring seat 18 in quadrature relationship. Annular inertial member. 27 is thus held in place by the contact'finger's but is free to move radially if sufiicient force is applied normal to shell 11. As a result of this freedom of movement'member 27 may be considered a floating mass.

\A complete electrical circuit is thus made between terminal 28 and conductive shell 11 whenever a sudden acceleration or deceleration in any direction occurs to the enclosure carrying this novel switch. It is also apparent that the circuit will be immediately reopened when the enclosure is at rest or is subjected to constant velocity. The switch may be modified by changing the loading of springs 21. and 22 or the length and/or cross sectional configuration of the various contacts. Also, the mass of the spring seats or of the inertia members may be varied. In such a manner, the total sensitivity or the sensitivity in any particular direction may be changed as desired. If the switch is to be responsive solely to forces along the longitudinal axis, as shown in FIG. 1b, inertial member 27 may be removed. However, if the switch is to be responsive solely to forces perpendicular to the longitudinal axis, as shown in FIG. 10, springs 21, 22 may be removed and spring seats 17 and 18 may be attached to end caps 12, 13 respectively.

Obviously many modifications and variations of the present invention are possible in the light of the above teachv ings. vIt is therefore to be understood that within the scope of the appended claims the invention may be practiced'otherwise than as specifically described.

What is claimed as new and desired to be secured by face selectively in accordance with the intensity and said rod like element within said hollow element and insulated therefrom, resilient means engaging said rod like element and electrically connected thereto for making contact selectively with said surface, an inertial member disposed on said rod like element, means for prevent- 7 ing longitudinal movement of said inertial member with respect to said rod like means, said last named means and said inertial member constituting a central member, a portion ofsaid resilient means engaging said central member, a second means for maintaining said central member and a second portion of said resilient means apart, whereby said contact means engages said surface selectively in accordance with the intensity and direction of force suddenly applied to said switch.

2. The apparatus of claim 1 wherein said second maintaining means is resilient, and said resilient means includes an inertial member.

3. The apparatus of claim 1 wherein said resilient means normally engages said first means.

4. A normally open switch comprising a rigid hollow conducting element having an inner contact surface, a rod like conducting element, a first means for maintainingsaid rod like element within said hollow element and insulated therefrom, a first inertial member slidable along said rod like means and electrically connected thereto, a first resilient means engaging said inertial member for making electrical contact selectively between said surface and said rod. like element, a central member disposed on said red like member, means for preventing longitudinal movement of said central member with respect to said rod like element, a portion of said contact means engaging said central member, a second resilient means interposed between said central member and said first inertial member, whereby said contact means engages said surrection of a force suddenly applied to said switch.

5. The apparatus of claim 4 wherein said central mem-' ber includes a second inertial member movable only in any perpendicular direction to the axis of said rod like member.

6. The apparatus of claim 4 wherein said second resilient means is a'spring encircling said rod like element.

7. The apparatus of claim 6 wherein said spring means normally biases said first inertial member against said first means.

8. A normally open switch comprising a conductive cylindrical shell, a conductive shaft, means for maintaining said shaft axially aligned within'said shell and insulated therefrom, a plurality of resilient conductive fingers for making contact 'selectivelywith the inner surface of said shell, a first inertial member 'slideably disposed on said shaft, said fingers being carried on said first inertial member, a'second inertial member, means for preventing longitudinal movement of said second inertial member with. respect to said shaft,' said last named means and said second inertial member constituting a central member disposed on said shaft, said fingers engaging said central member, spring means disposed on said shaft for initially maintaining said central portion and said first inertial member apart, whereby said fingersengage said shell selectively in accordance with the intensity and direction of forcesuddenly applied to said switch.

9. A normally open omni-directional inertial switch comprisingconductive shell, a conductive shaft, a pair of insulation rings attached to said shell and disposedon opposite ends of said shaft for maintaining said shaft centrally aligned within said shell, a plurality of spring seats disposed on said shaft, first and second of said spring seats being inertial members slidable on said shaft and each carrying four resilient conductive fingers arranged in quadrature relationship, said fingers making contact selectively with the inner surface of said shell, an annue lar inertial member encircling said shaft and disposed between a third and fourth of said spring seats, said annular member and said third and fourth spring seats forming a central member, means to prevent movement of said central member alongsaid shaft, the distance between said third and fourth-spring seats'being such as to prevent lateral movement of said annular member with respect to said conductive shaft, a first spring encircling said' shaft and disposed between said first and third spring seats, a" second spring encircling said shaft and disposed between said second and fourth spring seats, said springs normally biasing said first and second spring seats against each of said respective insulation rings, all of said fingers engaging said central portion, whereby said fingers engage said shell in response to movement of any of said inertial members selectively in accordance with the intensity and direction of force suddenly applied to said switch.

'10; The switch of claim 9 wherein the outer radius of said central portion is greater than the distance between the axis of said shaft and the point where said fingers engage said first and second spring seats, thereby causing said fingers to form an acute angle with a'line parallel to said shaft. a

1-1. The switch of claim -10 wherein the inner radius of said annular member is substantially greater than the radius ofthat portion of said shaft enclosed therein.

References Citedin the file of this patent UNITED STATES PATENTS 2,793,260 Ciosek May 21, 1957 2,851,554 Feng et a1. Sept. 9, 19 58

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