US2678360A - Vibrator - Google Patents

Description

May 11, 1954 M. O. BELLIS VIBRATOR Filed April 25, 1951 IN V EN TOR. MA ok/ce 0. $54 4 /s:

A TTORNEYS Patented May 11, 1954 VIBRATOR Maurice O. Bellis, Garden City, N. Y., ass'ignor to Servomechanisms, Inc., Mineola, N. Y., a corporation of New York Application April 25, 1951, Serial No. 222,876

3 Claims. (Cl. 20091) This invention relates to electromagnetic vibrators for periodically interrupting electric circuits and more particularly to a vibrator structure for attaining stable and dependable operation over long periods of operation.

With the application of vibrators of the reed type to precision electronic equipment for interrupting circuits, samplying voltages and the like, a very high degree of stability is required in order to attain the desired accuracies. This requirement is coupled with the ever present need for smaller components, which, in the case of vibrators, has been found to adversely affect both stability and dependability.

These difficulties have been overcome with this invention by the provision of a structure that will insure uniform reed operation substantially free from drift and which greatly lengthens the life of the device.

The above and other objects of the invention will become more apparent in the following description and drawings forming part of this invention.

In the drawings:

Fig. 1 is a perspective view of a vibrator in accordance with the invention to indicate the approximate size of the completed device;

Fig. 2 is a perspective view of the electromechanical vibrating assembly;

Fig. 3 is a longitudinal sectional view of the device of Fig. 1;

Fig. 4 is a transverse sectional view taken along the line 44 of Fig. 3; and

Fig. 5 is a longitudinal sectional view of an electromechanical vibrator assembly representing another embodiment of the invention.

As pointed out above, Fig. 1 illustrates the completed vibrator in approximately full scale. It comprises a base part If] having a plurality of metal prongs or connectors extending from one side thereof and a vibrator housing or cover l4 extending from the other side. As will be shown, the operating assembly is supported within the housing It and the entire unit is hermetically sealed to prevent the accumulation of dust and dirt in and about the vibrating parts. This structure also prevents the accumulation of moisture within the unit which may result in corrosion of the metallic parts or even short-circuit the contacts.

Referring now to Figs. 2, 3 and 4, the electromechanical vibrating assembly [5 is contained within a surrounding housing [8 of insulating material that is firmly secured within the outer housing M. The base It! is of a metallic material such as brass or the like with the prongs or pins l2a, I22), 120, [2d, He and 12 extending through insulating sleeves 28 mounted in the base and hermetically sealed to the base and the pins. These insulating sleeves may be of a ceramic frit material or other suitable insulating material that will enable the attainment of a good hermetic seal. The outer housing It is preferably sealed to the base It by solder as indicated at 22.

The insulating housing l8 holding the vibrator :6 also carries a winding or coil 24 adapted to be energized by a source of alternating current. This housing consists of a cylindrical part 26 having outwardly extending flanges 28 and 30 between which is retained the coil 24, the outer diameter of these flanges being substantially equal to the inside diameter of the case 44. A spacer ring 34 of rubber or the like and an insulating disc 32 are positioned between the insulating housing l8 and the closed end of the case M.

Within the insulating housing or spool 18 is the vibrator assembly It. It comprises a body 36 of brass or other suitable material of rectangular section with rounded corners and the maximum transverse dimension approximating the internal diameter of the insulating spool IS. The body is preferably fabricated by a suitable extrusion process to eliminate seams and to preserve its rigidity. The number of openings formed in the body is retained at a minimum.

In the inner end of the body 36 is a bar 38 of magnetized material placed directly against the lower wall thereof. Overlying this magnet is a second magnet 42 substantially coextensive therewith and separated therefrom by a spacing member of soft iron or the like. The thickness of this spacing member must be greater than the thickness of the vibrating reed plus the total travel thereof during vibration in order to provide adequate room for the vibration of the reed between the magnets 38 and 4'2. A strip 44 of high permeability metal such as mu metal, extends substantially the full length of the body 36 along the outer surface thereof and terminates at the end of the body adjacent the disc 32 in an .L-shaped part comprising a longitudinal leg 45 and a transverse leg 46. Leg 45 is disposed within the body 36 between magnet 42 and the inner surface of the adjacent wall of body 36 and leg 46 extends over the ends of the magnets 38 and 42. The length of the strip 44 and the position of the transversely extending leg 46 determine the phase relationship between the alternating current applied to the coil 24 and the action of the contacts operated by the vibration of the reed hereinafter to be described.

The series of elements just described are held in position within the body by a pair of screws 4'! threaded in the upper wall of the body 38 and bearing downward against the upper side of leg 45.

The vibrating reed t3 is fastened in the other end of the body 36 and is spaced from the bottom thereof by a spacing block to and a layer of insulating material 52. Overlying the reed and substantially coextensive with the block 58 are two layers of insulating material 54 and 5G, a contact carrying member 58, another layer of insulating material Gil, and a second spacing block. 52. These elements are retained in position by another pair of screws 54 threaded through the upper wall of the body 36 and brought to bear solidly against the block 62. The reed t8 carries a contact 66 of silver or other suitable material of at least equal density which cooperates with a contact 65 on the end of the contact carrying member 58. The end of the reed beyond the contact extends into the space between the magnets 38 and 42.

It has been found that for stable operation of the vibrator the travel of the reed and the maximum contact separation must be retained within very close limits. Also a high degree of rigidity of the various elements must be maintained. To attain these ends the layers of insulating material 52, 54, 56 and 69 are preferably formed of very thin sheets or mica or other form of material that will not deform under the high pressures placed on them. by the screws 64. Adjustment of the contact spacing and length of reed travel is accomplished by a pair of adjusting screws Hi and 12. The upper screw "it is threaded in the upper wall of the body 33 and carries on its inner end a bead of hard insulating material such as sapphire or the like which bears against the contact carrying member 58. The member 58 is formed of a resil ient material to adjust its position relative to the reed Q8. The lower screw 12 is similar to the upper screw and carries an insulating bead which bears against the underside of the reed 43 to limit its downward travel. The total contact separation for optimum operation has been found to be of the order of .0001" and to retain this separation and insure stable operation, the adjustment is made relative to the body 36 and wholly independent of the means for supporting the reed 48 and the member 58. Thus slight chang in the thickness of the insulating material spacing these elements will have a negligible efiect on the operation of the reed.

The electrical connections to the vibrator are accomplished by means of the pins I2a I2f, two of the pins 52a and I2?) being connected to the coil 2G by wires I4 and I6 respectively and two other of the pins being connected to the reed and contact carrying member by means of insulated leads I8 and 8D.

The pins to which the leads I8 and 80 are connected do not show in the section illustrated in Fig. 3 but are identified in Fig. l as pins I and I2cl respectively. To minimize the effect of electrical noise, a sheath 8| of metal foil is provided about the barrel 26 of the insulating body I8 and this sheath is electrically connected by a lead 82 with a pin I2e (see Fig. 1) which, through the cooperating terminal of the vibrator socket (not shown) is connected to the grounded side of the power supply. A sixth pin, I21, is connected by a lead 83 to base It and case II for grounding of these parts.

To secure dependable operation of the vibrator it is important that the metal parts be adequately cleansed of all foreign material that may break loose and accumulate in and about the contacts. Conventional cleansing means such as boiling or heating have not been found to be entirely satisfactory as particles not removed in the cleansing may be loosened during vibration. It has been found, however, that the life of the device can be materially increased by actually closing off or sealing the pores of the reed and contact carrying member after cleansing. Good results have been obtained by silverplating these parts, although other similar plating metals having an equivalent density may be used.

In assembling the above described device, after the metal parts have been cleansed and the reed and contact arm silverplated and mounted in the vibrator unit It, the unit is inserted in the insulating member I8 carrying the coil 24, the electrical connections to the pins in the base are made and then the housing I4 is slid over the assembly. Prior to soldering the housing to the base, all air and moisture is evacuated from the housing and the housing filled with nitrogen or other dry inert gas, several fiushings with nitrogen preferably being made prior to the final filling of the housing. The housing is then hermetically sealed to the base and the device is ready for operation.

In the operation of the vibrator, an alternating 7 current is applied to the coil 24 which produces a magnetic field that during one-half cycle supplements the effect of the magnet 38 on the reed 4B while neutralizing the efiect of magnet 42 on the,

reed and during the succeeding half cycle supplemerits magnet 42 while neutralizing magnet 38. When the effect of the magnet 38 is neutralized and that of magnet 42 augmented, the contacts 66 and 68 will close and, conversely, when magnet 38 is augmented and magnet 42 neutralized, the contacts will open. The phase between the alternating current and the action of the contacts. is controlled by the strip M the position of which is initially adjusted during assembly of the vibrator. This factor is of great importance in precision equipment such as servomechanisms and the like in order to enable substitution of one vibrator for another without necessitating realinement of the equipment.

The form of the invention described above was of the single-pol single-throw type. In Fig. 5

there is illustrated a single-pole double-throw viorator embodying the invention. In this embodiment, IGII denotes the rectangular body of brass or similar material. As in the previous embodiment, a permanent magnet N32 is mounted in the right end of the body I08 but is spaced from the bottom wall by a spacer IIII of brass or the like. Overlying the magnet IE2. is a soft iron spacer I04, a magnet I06 substantially coextensive with the magnet I02 and the leg III] of the L-shaped end of a strip I08 of high permeability metal. These elements are firmly held in position by the setscrews I I2 threaded in the upper wall of the body I00.

In the other end ofthe body is a metallic spacer IIG, a layer of insulating material H6, 2.

first contact carrying member IIB of resilient metallic material, layers of insulating material I20 and I22, the vibrating reed I24, layers of insulating material I26 and IZ'I, a second contact carrying member I28, insulating material I30 and a metallic spacer I32. These elements are held in position by the set-screws I34 in the manner described in connection with the previous embodiment shown in Fig. 3.

The reed I24 extends between the magnet I02 and the magnet I06 and carries contacts I36 and I 38 on opposite sides thereof. These contacts are preferably formed of silver or other suitable conducting material. The contact carrying members H8 and I28 extend slightly beyond the reed contacts I36 and I38 and carry contacts I40 and I42 for cooperation with the reed contacts.

The position of the contact carrying members I I8 and I28 is adjusted by set-screws I44 and I46, respectively, carried directly by the body I and thus the position of these members is substantially unaffected by any change that may occur by reason of compression of the layers of insulating material. The set-screws I 44 and I46 each carry an insulating bead of sapphire or the like to insulate the screw from the associated contact carrying member.

It will be understood that the above described vibrator assembly of Fig. 5 will be located like the vibrator assembly I6 of Fig. 3 within the insulating body I 8 carrying the coil 24 and that the contact carrying members, the reed and the coil will be electrically connected to terminal pins on the base I0, an additional terminal pin being of course provided for connection to the second contact carrying member. The operation of the vibrator of Fig. 5 will be clear from the description already given of the operation of the vibrator of Figs. 2 to 4. The only difference in the operation of the two devices is that the reed of Fig. 5 operates as the moving element of a single-pole double-throw switch and hence closes one circuit when opening another, whereas the reed of Figs. 2 to 4 operates as the moving element of a singlepole, single-throw switch and hence alternately opens and closes a single circuit.

With this invention a high degree of stability, dependability and uniformity can be attained in vibrators even of the miniature type notwithstanding the exceedingly small tolerances encountered. The above described vibrators can be so fabricated as to fit within an external housing of the order of 1% inches in length and inch diameter, the vibrator unit being about 1 inch in length. The provision of the two magnets positioned on opposite sides of the end of the reed and cooperating with the actuating coil insure dependable and positive operation of the reed both at opening and at closing of the contacts, the silver or other metal plating of the reed and cooperating contact carriers insure long and effective useful life of the device and the adjusting means for controlling the spacing of the contacts and for limiting the travel of the vibrating end of the reed insure precision operation of the device.

The invention has now been described with reference to two specific embodiments thereof. Obviously various changes could be made in the particular constructions illustrated and described without departing from the spirit of the invention or the scope of the accompanying claims.

I claim:

1. A precision electromechanical vibrator comprising a hollow body of rectangular transverse section and of non-magnetic material, a pair of permanent magnets clamped in one end of said body on opposite sides of a soft iron spacer block, said magnets extending beyond said spacer block toward the other end of said body to define an air gap therebetween, a laminated structure comprising layers of insulating material, a vibratory reed and at least one resilient member clamped in the other end of the bod with the free end of the reed positioned in said air gap and the free end of the member overlying part of the reed, cooperating contacts on said reed and on said member, means in one side of said body, and bearing against the free end of said resilient member for fixing its position relative to the reed, means in another side of said body to limit the movement of the reed away from said member and a coil adapted to be energized by alternating current encompassing said body in the neighborhood of said permanent magnets.

2. The vibrator according to claim 1 including a tubular housing of insulating material interposed between said body and said coil and supporting said coil.

3. The vibrator according to claim 2 including an electrically grounded sheath of metal foil interposed between said housing and coil for minimizing electrical noise.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,383,174 Udy et a1 June 28, 1921 1,583,792 Niles May 11, 1926 1,900,256 Payette Mar. 7, 1933 2,015,156 Richmond Sept. 24, 1935 2,264,022 Ellwood Nov. 25, 1941 2,423,524 Side July 8, 1947 2,471,594 Weightman May 31, 1949 2,473,353 Aust June 14, 1949 2,479,566 Haberland Aug. 23, 1949 2,486,394 Eannarino Nov. 1, 1949 2,491,907 Reifel et al Dec. 20, 1949 2,547,947 Kleis et al Apr. 10, 1951

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