US2964603A - Chatter switch - Google Patents

Description

Dec. 13, 1960 A. R. PIATT ETAL CHATTER SWITCH Filed Aug. 6, 1945 United.

CHATTER SWITCH Alvin R. Piatt, United States Navy, Washington, D.C. (204 S. Beachwood Drive, Burbank, Calif.), and Ronald O. Beach, Naval Ordnance Laboratory, Navy Yard, Washington, D.C.

This invention relates generally to chatter switches and more particularly to improvements in a chatter switch for use in underwater ordnance which is adapted to be set in operation in response to acoustic energy received thereby through the water.

lt is an object of the present invention to provide a new and improved acoustically controlled switch device responsive to sound signals resident within a predetermined frequency range.

Another object is the provision of a new and improved chatter switch which is extremely sensitive whereby the switch is rendered responsive to small amounts of acoustic energy received thereby.

Another object is to provide a new and improved chatter switch in which two vibrating systems are employed whereby the range of frequency response of the switch is broadened and the sensitivity thereof increased.

Still another object is the provision of a new and improved acoustically controlled chatter switch for use in marine mines, depth charges and the like wherein the static pressure on the flexible element in communication with the surrounding water is balanced.

A further object is to provide a new and improved chatter switch responsive to sound pressure signals the component parts of which will not be impaired as a result of abnormally large amounts of acoustic energy being received thereby.

In accordance with the preferred embodiment of the presentk invention, two vibratory systems are employed, one of which comprises a diaphragm in communication with the water and a mass secured thereto and is tuned to a predetermined frequency. The remaining vibratory system comprises a vibratory reed carrying a second mass and is tuned to substantially eighty percent of the resonance frequency of the tirst vibrating system. A pair of normally closed, electrical contacts are utilized, one of the contacts being carried by a balance wheel mounted on a shaft and rotatable therewith. A resilient spring member is also mounted on the shaft for yieldably maintaining the balance wheel contact in normal continuous engagement with the other contact which is aixed to the mass of the second vibrating system, suitable adjusting means also being provided for varying the tension exerted by the spring member thereby to adjust the pressure between the contacts. The instant device is adapted for use in tiring control systems for marine mines and the like and as sound signals of predetermined character impinge against the outer surface of the diaphragm, the contacts are caused to be disengaged at intervals thereby to initiate the operation ofthe tiring control system.

For a detailed description of the structure and operation of the invention, reference is made to the following description taken in connection with the accompanying drawings of which:

Fig. 1 is a sectional view of the switch of the present invention according to a preferred embodiment thereof;

. Fig. 2 is a fragmentary sectional view taken substantially along the line 2-2 of Fig. l;

Patent ice Fig. 3 is a sectional view taken substantially along the line 3-3 of Fig. 2;

Fig. 4 is a view in section taken substantially along the line 4-4 of Fig. 3;

Fig. 5 is a fragmentary view in section taken substantially along the line 5--5 of Fig. 3; and

Fig. 6 is a fragmentary sectional view taken substantially along the line 6--6 of Fig. 3.

Referring now to the drawings for a more detailed description of the invention, there is shown thereon a chat- -ter switch or sound responsive device generally designated by the numeral 10 and comprising a ring member 11. A housing 12 for the switch is secured to the member 11 by means of a circular flanged portion 13 aixed to the housing and having a plurality of holes therein for receiving the screws 14. Also secured to the ring member 11 by the screws 15 is a circular plate 16 with a thin flexible diaphragm 17, preferably circular in shape and of a material suitable for the purpose such, for example, as stainless steel, clamped therebetween by the screws 15. A suitable gasket 18 is disposed between the ring member 11 and the diaphragm 17 to insure a watertight connection therebetween.

A mass or post 19 extends through the diaphragm 17 and plate 16 and is provided with a threaded extremity adapted to receive the nut 21 whereby the post is securely clamped to the diaphragm and is caused to vibrate in sympathy therewith, the diaphragm and post assembly comprising a first vibrating system. A suitable gasket 22 is provided between the nut and diaphragm to insure a watertight relation therebetween. It will be understood, of course, that it is essential to tune the diaphragm 17 to a predetermined frequency and maintain the frequency response thereof at such predetermined value. ln the instant device, the mass carried by the diaphragm may be varied to adjust the frequency response of the diaphragm and first vibrating system by using nuts of different weights in securing the post to the diaphragm. In order to maintain the adjusted resonance frequency of the first vibrating system it is necessary to provide a diaphragm having a constant effective area, the term effective area as employed herein being defined as that portion of the outer surface of the diaphragm which is in communication with the water and adapted to receive sound signals transmitted therethrough. This is accomplished here by preventing any flow of gasket material onto the effective area of the diaphragm. It will be noted that the channel cut into the ring member 11 for receiving the gasket 18 has a chamfer 23 cut therein in a direction away from the effective area of the diaphragm such that the gasket material fills the chamfer as the screws 15 are tightened.

The nut 21 also has a chamfer 24 cut into the gasket channel thereof, the outer edge of the nut being lower than the inner edge, thereby facilitating metal to metal clamping and preventing the flow of gasket 22 onto the effective area of the diaphragm.

Secured to the circular plate 16 by the screws 25 are two mounting strips 26 and 27, each being insulated from the other and from the screws by a suitable strip of insulating material 28 such, for example, as rubber, Bakelite or the like, the strip 27 also being insulated from the plate 16 by an additional strip of similar insulating material. The mounting strip 27 has two upright portions 29 and 31, the portion 29 having a threaded hole therein adapted to receive the adjustable screw bearing 32, the portion 31 also being provided with a threaded hole therein adapted to receive the adjustable screw bearing 33. A lock nut 34 is disposed about the screw bearing 33 for maintaining the bearing 33 in an adjusted position with respect to the upright portion 31.

u Disposed about the screw bearing 32 is an internallyT bored, circular member 35 and releasably clamped between the member 35 and the upright portion 29 by the screws 36 is a ring member 37 having a relatively large inside diameter with respect to that of the member 35. Extending from the member 37 is an arm 38 which may be rotated to any desired setting by loosening the screws 36 and rotating the ring member 37. Secured to the arm 38 is a resilient spring 39 known in the trade as a hairspring, the other end of which is afxed to a shaft 41. The shaft 41 is tapered at the ends thereof and is mounted for rotationin the bearings 32 and 33.

An inertia member or light weight balance Wheel 44 is secured to the shaft 4l and rotatable therewith, the wheel 44 having mounted thereon an L-shaped electrical contact member 45 with the depending portion thereof being tiled to a sharp point and yieldably held by means of the hair spring 39 in continuous normal engagement with another electrical Contact member 46. The contact member 45 is composed of any suitable lhard conducting material such, for example, as platinum iridium while the contact member 46 is composed of any suitable soft conducting material such, for example, as gold. It has been found that the use of the aforedescribed Contact arrangement provides a more positive make action of the contacts for the reason that the platinum iridium cont-act, upon engaging the gold contact, pierces any oxide coating which may have formed on the gold contact. Moreover, on continued vibration of the contacts, the hard contact causes a cold tiow of the soft contact each time contact is made therebetween whereby a wiping action of the contacts is produced.

The contact member 46 is carried by a mass 47, the mass being aihxed to a vibrating reed 4S composed of a suitable length of Inconel wire, the post 19 has a hole cut therein for receiving a Kovar seal device 49, to which device the vibrating reed 48 is connected. The reed and mass iti carried thereby comprises the second vibrating system of the present invention and as heretofore described is tuned to approximately eighty percent of the resonance frequency of the rst vibrating system by varying the length of the reed 4S.

An electric circuit is completed through the normally closed contacts 45 and 46 by soldering a conductor 51 to the mounting strip 26 which is electrically connected to contact 45 and by soldering another conductor 52 to the sealing device 49 which is electrically connected to con tact 46, the conductors being adapted to carry electrical energy from any suitable source. It will be noted that an ad-ditional mounting strip 42 is provided intermediate the strips 26 and 27, the strip 42 having an upright portion 43 formed integrally therewith and adapted to receive the mass 48 through a hole provided therethrough thereby to limit the vibrational amplitude of the second vibratory system.

A suitable cup-shaped cover 53 is secured to the circular plate 16 lby la plurality of screws 54, which cover has arranged therein a partition 55 having a flanged portion 56 wherein a hole is drilled to receive the post 19 and to guide the post as it vibrates. ln order to prevent corrosion of the various switch elements contained within the cover 53, a suitable dehumidifying agent is employed and arranged within Ia bag o as shown in Fig. 2 of the drawings.

The instant device is further provided with a rubber sack 57 arranged within the housing 12, the sack being securely clamped between the ring member i1 and the flanged portion i3 of the housing. Cut into the hanged portion are a piurality of ports 53 which allow water to pass into the space between ,the housing 12 and kthe rubber sack 57 when the chatter switch is submerged within a body of water, thereby causing the sack to collapse and the air enclosed therebyto be compressed. A plurality of holes 5i) and 645 are cut in the circular plate 16 and in the bottom ,of the cover 53 respectively in order that the air enclosedflby the sack and compressed -upon the collapsefthereof may be applied to the inner surface of the diaphragm 17 to balance the water pressure on the outer surface thereof. r[he perforations 59 in the plate 16 also serve to reduce the air damping eect on the inner surface of the diaphragm thereby increasing the sensitivity thereof. The cover 53 prevents the rubber sack from disturbing either of the vibrating systems as the sack collapses.

It is important to note that in order to balance the static pressure on the outer surface of the diaphragm it is necessary to have properly designed ports for admitting water into the device. If the ports 5S are too large, sound pressure waves impinging against the outer surface of the diaphragm would be equalized by sound pressure waves reacting on the inner surface thereof through the ports 5,8. Conversely, if the ports were too small, the possibility of clogging is greatly increased. In order to maintain the proper sized ports, each is lined with a cylindrical piece of Saran tubing which prevents the ports from rusting, freezing and clogging.

A suitable housing assembly 6l is secured to the housing 12, the assembly 61 having holes cut in its top and bottom surfaces through which a cable 62 containing conductors 5ft and 52 is passed. A plurality of holes are also cut in the housing 12 to allow passage therethrough of conductors 51 and 52, with suitable encasing means 63 being provided at each hole in the housing l2. lt will be noted that the sack 57 is securely clamped between the assembly 61 and the housing 12.

A brief description of the operation of the chatter switch will now be given. As heretofore described, the first and second vibrating systems are each tuned to a different frequency such that the actual frequency response range of the diaphragm 17 included inthe first system is increased. When sound signals having a frequency content resident within the frequency response range of the diaphragm impinge against the outer surface thereof, the diaphragm and its associated mass 19 are set in vibration. When this occurs, the vibrating reed 48 and its associated mass 47 comprising the second system are set in vibration, the amplitude of which is greater than the vibrational amplitude of the diaphragm. As the mass 47 vibrates the contacts 45 and 46 are caused to vibrate since the inherent resonance frequency of the balance wheel and Contact 45 is extremely small with respect to the frequency of vibration of contact 46. Thus, as contacts 4S and 46 vibrate an electrical circuit comprising the contacts is interrupted at intervals, such periodic interruptions being utilized in any suitable manner to initiate the operation of a ring circuit to detonate an explosive charge.

It will be understood that the pressure maintained between the contacts 45 and 46 by the hairspring is adjustable so that the -amplitude as well as the frequency of sound signals adapted to operate the switch may be controlled. The circular plate i6 is adapted to limit the vibrational amplitude of the diaphragm whereby abnormally large amounts of energy transmitted Vthrough the water and reaching the chatter switch will not cause damage to any of the elements thereof.

From the foregoing, it should now be apparent that au acoustically controlled switch has been provided which is well adapted ,to fulfill the aforesaid objects of the inven-` tion.

While the invention has been described with particular reference to an example thereof which gives satisfactory results, it will readily be apparent to those skilled in the art to which the invention appertains, after understanding the invention, that further embodiments, modifications and changes may be made without departing from the spirit and scope thereof as defined 1oy the claims appended hereto.

T he present invention may be manufactured and used by or -for the Government of the United States of America for governmental purposes without payment of any roya'i ,ties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A device of the character disclosed adapted to be immersed in a body of water and comprising a casing having a plurality of openings therein and enclosing a space, a plate member having a plurality of perforations therein and secured to said casing within one of said openings, a first vibratory member covering said one of said plurality of openings and clamped between said plate and said casing, said plate being adapted to limit the vibrational amplitude of said rst vibratory member, a second vibratory member coupled to said iirst vibratory member, a pair of contact elements, means secured to said plate for pivotally mounting one of said pair of contact elements, means including said second vibratory member for vibrationally mounting the other of said pair of contact elements, means settable at will for yieldably urging said pair of contact elements into mutual engagement, and a normally expanded air-lled collapsible member covering the other of said plurality of openings for providing a chamber in communication with said space, said collapsible member being responsive to water pressure thereby to balance the pressure on the inner surface of said first vibratory member with the water pressure on the outer surface thereof when the device is in a state of rest.

2. A device of the character disclosed adapted to be immersed in a body of water and comprising a casing having an opening therein and enclosing a space, a plate member having a plurality of perforations therein and secured to said casing within said opening, a rst vibratory member covering said opening and clamped between said plate and said casing, said plate being adapted to limit the vibrational amplitude of said first vibratory member, a second vibratory member coupled to said first vibratory member, a pair of contact elements, means secured to said plate for pivotally mounting one of said pair of contact elements, means including said second vibratory member for vibrationally mounting the other of said pair of contacts, means settable at will for yieldably urging said pair of contact elements into mutual engagement, a normally expanded air-filled collapsible member for providing a chamber in communication with said space, said collapsible member being responsive to water pressure to balance the pressure on the inner surface of said first vibratory member with the water pressure on the outer surface thereof, said casing also having a plurality of ports therein for allowing water pressure to react upon said collapsible member, a plurality of cylindrical members respectively disposed within said plurality of ports and composed of material adapted to prevent the ports from clogging, and means secured to said plate member for preventing said collapsible member from impairing the operation of said device upon the collapse thereof.

References Cited in the le of this patent UNITED STATES PATENTS 1,232,624 Taylor July 10, 1917 1,832,761 Brady Nov. 17, 1931 2,075,774 Allen Mar. 30, 1937 2,207,292 Hensel et al. July 9, 1940 2,396,699 Hayes et al Mar. 19, 1946 2,401,934 Hester June 1l, 1946

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