US3152270A

US3152270A - Two pole transducer

Info

Publication number: US3152270A
Application number: US16429A
Authority: US
Inventors: James A Ross
Original assignee: Ling Temco Vought Inc
Current assignee: Ling Temco Vought Inc
Priority date: 1960-03-21
Filing date: 1960-03-21
Publication date: 1964-10-06
Anticipated expiration: 1981-10-06

Description

Oct. 6, 1964 J. A. Ross 3,152,270

TWO POLE TRANSDUCER Filed March 21, 1960 4 Sheets-Sheet 1 INVENTOR.

JAMES A. ROSS AGENT 1964 J. A. Ross 3,152,270

TWO POLE TRANSDUCER Filed March 21, 1960 4 Sheets-Sheet 2 FIG. 3.

FIGQ9.

INVENTOR. JAMES A. ROSS AGENT Oct. 6, 1964 J. A. Ross 3,152,270

TWO POLE TRANSDUCER Filed March 21, 1960 4 Sheetshe 3 FIG. 7.

FIG. 8. 5s;

INVENTOR. JAMES A. ROSS AGENT Oct. 6, 1964 J. A. Ross 3,152,270

TWO POLE TRANSDUCER Filed March 21. 1960 4 sheets sheet 4 FIG. IO.

FIG. II.

FIG. l2. I

I6I e2 [{AMPLIFIER" DE LAY 7o 94 I56 I5I T 95 I62 83 as AMPLIFIER DELAY I 96 I57 I52 T 91 i I63 84 gngAMPLlFlER DELAY I58 I53 T 99 I AMPLIFIER DELAY 85 E IOO I5 I54 T MPLIFIER DELAY 9| I A I02 I60 I55 T I 3 INVENTOR.

JAMES A. ROSS AGENT United States Patent 3,152,270 TWO POLE TRANSDUCER James A. Ross, Orange, Califi, assignor to Ling-Temco- Vought, Inc., Dallas, Tex a corporation of Delaware Filed Mar. 21, 1960, Ser. No. 16,429 28 Claims. (Cl. 310-47) My invention relates to an electrical to mechanical transducer and particularly to such transducers having a flat conductive plate-like armature and a field structure to pass magnetic flux transversely through said plate.

The armature of the well-known electrodynamic loudspeaker type of electromechanical transducer consists of a circular coil of wire, a form to support the same and spider-like means to mechanically connect the form to a useful load.

I have previously invented a four pole transducer, which is described in my application for United States patent Serial No. 749,539, filed July 18, 1958, now Patent No. 2,944,194, issued July 5, 1960. In this four pole transducer the armature is in the form of a piece of crossshaped electrically conductive metal with four magnetic poles laterally adjacent to the arms of the cross.

This application is concerned with a new and highly simplified form of transducer in which the armature is effectively a fiat plate and only two magnetic poles are required to provide a suitable flux pattern for the armature. Not only is this an important simplification, but the new structure provides convenient structural advantages.

Briefly, these advantages embrace a field structure in which the flux density at the air-gap is the same as in the remainder of the magnetic structure, an alternate type of field structure in which connections to the armature are easily made, and a shape of armature that is particularly adapted for driving loads supported on a slip table. By way of comparison, the flux density at the airgap in my four pole transducer is only 70% of the maximum flux density in the field structure of that device. The maximum density occurs at the throat between pairs of pole pieces. The throat is required in the four pole transducer to provide room for the four pole armature.

Alternate embodiments provide a particularly simple field structure and laminated armature structures for either sonic phase drive or relatively high electrical input impedance to the transducer.

An object of my invention is to provide an electromechanical transducer having an armature of great simplicity.

Another object is to provide an electromechanical transducer having an efilcient field structure.

Another object is to provide a field structure that allows convenient external connections for the armature of an electromechanical transducer.

Another object is to provide an armature that is particularly mechanically suited to drive a specimen upon a vibration slip table.

Another object is to provide a unified connection scheme for both armature and shading conductors in an electromechanical transducer.

Another object is to provide an armature of simple structural shape but of relatively high electrical input impedance.

Another object is to provide a structure for an electromechanical transducer that is simple, of relatively light Weight and which has rugged principal parts.

Other objects will become apparent upon reading the following detailed specification and upon examining the accompanying drawings, in which are set forth by way of illustration and example certain embodiments of my invention.

3,152,270 Patented Get. 6, 1964 PEG. 1 shows an end perspective view of the essential structure of my transducer,

FIG. 2 shows a horizontal section along lines 2-2 in FIG. 1, showing the manner in which external connections are made in one form of armature,

FIG. 3 shows an end elevation view of an alternate embodiment of my invention in which a particularly simple field structure is employed,

FIG. 4 shows a side elevation of a structure in which the plate-like armature of my invention is employed with a slip table,

FIG. 5 shows principally a plan view of a sectionalized armature,

FIG. 6 shows an end view of the armature of FIG. 5 in combination with adjacent shading conductors,

FIG. 7 shows a side sectional elevation of a sectionalized armature and associated structure,

FIG. 8 shows a wiring diagram for the armature and associated structure of FIG. 7,

FIG. 9 shows an alternate form of the transducer of FIG. 4,

FIG. 10 shows a curved armature embodiment similar to FIG. 3,

FIG. ll shows a curved armature embodiment similar to FIG. 4, and

FIG. 12 shows connections for delayed armature feed according to FIGS. 5 and 6.

In FIG. 1 numeral 1 indicates the iron field structure. This has the approximate shape of tangent double cylinders with a common central slot Within which armature 2 fits. At least two field coils 3 and 4 individually surround the toroid-like iron structure on opposite sides of the center of the assembly. These coils pass through central holes in each cylinder as well as encompassing the outer surface and the two end surfaces.

Normally, a constant current of a number of amperes is passed through both coils 3 and 4 in the proper direction to produce a mutually aiding magnetic field in the structure as a whole. One magnetic pole is formed above the central slot, as indicated at N, and the opposite pole is formed below the slot, as indicated at S. The magnetornotive force thus provided normally saturates the field structure, at a flux density of the order of 100,000 lines per square inch.

It will be seen that relatively uniform magnetic flux thus passes across the slot perpendicularly to the plane or" the flat armature 2. Electrical connections are provided at the narrow sides of the armature and an alternating current is caused to flow through the armature plate in FIG. 1 from left to right, and vice versa according to the electrical alternations. This causes motion of the armature up and down through the plane of the paper (the motor rule).

Although the magnetic and electrodynamic aspects of the structure of FIG. 1 are symetrical with respect to armature 2, the auxiliary aspects are not. These have to do with passing the current into and out of the annature; i.e., the connections. Broadly, these pass to the external circuit at one side; the right side in FIGS. 1 and 2.

Stationary shading conductors or sheets are provided on the pole faces of the field structure to reduce the inductance of the armature system. In the present instance these are placing on both sides of the slot in the field structure, and in FIG. 1 are identified as 5 on the upper pole and 6 on the lower. These sheets are insulated from the field structure, are mechanically a part of it and are coextensive with the armature.

The excitation circuit of the transducer of FIGS. 1 and 2 consists of armature 2 in series with shading sheets 5 and 6 in parallel. The excitation circuit is connected to power input means, such as impedance-reducing transformer 7. In detail, a copper strap secondary a; of transformer 7 connects to a number of flexible high-conductivity armature connection straps 9, lil, ll, l2, l3, 34. A nut-bolt assembly 15' is shown as accomplishing this juncture. Large and clean surfaces of contact should be arranged, since the impedance of the whole excitation circuit is only a small fraction of an ohm. Alternately, the contact may be formed by brazing or welding.

The armature connection straps pass through slots in the field structure I in order to reach the armature proper. The respective slots and the electrical insulation provided on all the faces thereof are identified in FIG. 2 as 1.6, 17, l3, 19, 2t 21. In a relatively high power embodiment of my invention in which the length of field structure 1 might be two feet, the open area of each slot is of the order of several inches in depth by a fraction of an inch in width. The corresponding straps are smaller so that some mechanical motion is possible within the slots. The chief mechanical fiexure, however, occurs to the left of the slots and to the right of the armature proper in FIG. 2. In this volume the straps branch out so that exciting current is relatively uniformly distributed over the fiat armature. An excess in strap length is provided to accommodate the necessary vibration of the armature, the direction of which is indicated by the two-headed arrow 22. The central straps, as 18, 19 and perhaps 17 and 2%, have a further excess length to equalize the resistance be tween the several straps. This is also carried out in practice adjacent to the bolt connection 15, but has not been shown in FIG. 2 for sake of clarity.

Alternately, the straps 9 through 14 are a tight fit in the field structure by narrowing slots 16 through ill. The cross-section of iron in the field structure is main tained approximately constant by providing proiections 2d and 25.

Armature connection straps 9 through 14 are arranged to make a low resistance electrical connection with armature 2 by brazing, silver soldering, welding, etc., by passing into tight-fitting slots therein and then bonded. Six straps are shown; more or fewer may be used. Top strap 9 appears in FIG. 1.

On the left side of armature 2 connection is made the two shading sheets 5 and d by curving one piece of high conductivity metal, as copper, into a semicircle at 27 in FIG. 2, so that sheets 5, 6, and end connection 27 are all one. At 2'7, a number of

flexible straps

28, 29, 36, 31, 32, 33 connect from armature 2 to end connection 27. The number, material and fastening may be the same as discussed for the right-hand armature connections 9 through 1 An alternate left-hand connection is shown in FIG. 1. A connection bar 35 is provided, to which the several flexible connections 23, etc. are fastened. In turn, two sheetllliG connections 36, 3'7 connect the length of the bar to shading sheets 5, 6, so that the electrical scheme of connections is as before.

In a manner similar to that described, electrical connection is made between the right-hand ends of shading sheets 5, 6. These connections are arranged out of mechanical conflict with the armature connection straps 9 through 14-, as straps 39, dd; front and back with respects to the armature straps in the plan view of FIG. 2 to cross over the shading sheet connections from one side to the other of the main field structure slot. On each end of the slot straps 59, 4h curve toward the center to connect the whole ends of the shading sheets (FIG. 2).

External connection 41 connects with connection 39 and becomes one with secondary 8 of transformer 7. An additional connection to the same end of secondary 8 may also be taken but has not been shown since it is optional.

Primary 44 of transformer '7 has considerably higher impedance than secondary The ratio is normally from a small fraction of an ohm for secondary 8 to several ohms for primary 44 This primary is then connected to the low impedance secondary of the output transformer of the high power audio amplifier employed to drive this transducer and the primary of the output transformer is connected to the plates of the vacuum tubes as known.

In case a low impedance driving source is available, as the multi-rectifier device of the High Power Synthetic Waveform Generator of Ross and Harter, patent application No. 850,595, filed November 3, 1959, one transformer 7 is sufi'icient to accomplish the necessary impedance conversion.

An alternate embodiment of my invention is shown in FIG. 3, wherein a toroid of iron 51 has a single air-gap along a radius. The central hole of the toroid allows a field winding 54 to encircle the same and to provide a magnetic flux as before when current is passed through the field winding. Armature 52 has the structural form of a flat conductive plate and is centered in the gap in the field structure, all as before. The armature may be composed of many laminations as will be later described but the structural form is the same.

Only one field coil is required and has been shown. More can be added around the toroid if desired for practical reasons. One magnetic pole, say a north pole N is formed on the upper pole face and the opposite pole, S, on the lower pole face. Shading sheet 55 is insulatingly attached to the stationary N pole and shading sheet .56 is similarly attached to the lower S pole.

Because the left-hand edge of armature 52 is not confined by the field structure almost any arrangement of electrical connections to the armature can be had. The first of a series of flexible strips 59 is shown. Others of the same nature as 28, 2%, etc. in FIG. 2 are behind strip 59. These each attach to both the armature and a stationary connection bus 60. The latter, in turn, is connected to one end of a low impedance secondary 58 of transformer 57. The

shading sheets

55 and 56 extend beyond the field structure to the left and connect to the other end of secondary 58. An additional low imped ancc secondary 68 of transformer 57 is connected in parallel to secondary 58. This alternate construction allows smaller conductors to be employed than as shown at 8 in FIG. 2. A higher impedance primary 61 completes transformer 5'7 and this primary is connected to electrical enervy exciting means as has been previously described.

At the right-hand side of armature 52

shading sheets

55 and 56 are formed together in a curved portion (53 and a series of flexible armature connections are connected thereto, of which connection is at the front and so is seen.

In either the embodiment of FIG. 1 or 3 the armature is retained in slidable relation to the stationary portion of the structure by means of high pressure oil. A known oil pump suited to provide oil pressure, a gear type proportional flow divider and suitable pipes meter an equal amount of oil to each pole face N and S. Through holes drilled in the field structures relatively perpendicular to the pole faces, as at 42, 43 in FIG. 1 and at 66, 67 in FIG. 3, the oil flows from the piping system to substantially the center of each pole face.

The oil is distributed over the whole face of the shading sheet, by, for example, a spiral groove cut outwardly from the central hole. A noticeable separation has been shown between the armature and the shading sheets in the figures herein for sake of clarity but this distance is only a few thousandths of an inch in practice. The equalized oil pressure holds the armature centered in the field gap in each case and provides a cushion of lubrication upon which the armature slides when it is supplied with actuating current. A thin transformer oil having an S.A.E. equivalent of five is employed, an example of which is Shell Dyala oil.

While I do not restrict the application of my invention, orientation of the structure so that armature plate 2 lies in a horizontal plane has certain advantages. Re-

storing springs are not required. This results in simplicity and improved fidelity of vibration over the more common orientation of the armature in the vertical position.

As a practical matter, two or more weak springs may be employed at convenient points, as the corners of the armature, to insure that it remains well centered. However, this function can be taken over by the several electrical connecting straps 9 through lid and 28 through 33 by providing these with spring-like properties. Should it be desired to operate the transducer with the armature vertical, suitable leaf springs may be provided as shown and described in my prior four-pole transducer patent.

Typical horizontal operation of the armature is shown in FIG. 4. Here a common baseplate 7th acts as the overall base of the machine. It may be provided with casters for mobility. A field structure 71 of th embodiment of FIG. 3 is seen in side elevation. Armature 72 extends in one piece from within the field structure, as in FIG. 3, to completely over a black granite block '73. An oil film between the granite block and the extended portion of the armature 72 allows vibration of the armature to take place under the load of specimen 75. The latter is bolted or clamped directly to armature 72 and a vibrating system of ideal simplicity results. If the specimen is to be vibrated in another plane it is merely bolted to the armature in another position. A portion of the field excitation winding '74 is seen at the left in FIG. 4.

It is obvious from this construction that the vibrationally complicated structure of the prior art including moving coil, spider and specific work table is eliminated. Consequently, so are turning moments and the possibility of parasitic vibrations. My simple moving system is suited to follow the waveform of the incoming alternating current with fidelity.

Armature 72 may be made of a single piece of aluminum, aluminum alloy or beryllium, or the armatures of FIGS. 1, 2 or 3 may be extended by arranging studs in tapped holes 46 or fittings on bosses 126 in FIG. 7.

FIG. 5 shows an electrically sectionalized armature provided to be driven in vibrational phase at high frequencies and FIG. 6 shows how this armature coacts with its immediately adjacent shading conductor and field structures. Should the armature of FIG. 5 (a plan view) be of the order of 20 inches long, this length corresponds to a quarter-wavelength in aluminum for an audio frequency of 3,000 cycles. A quarter-Wavelength is the distance from a node to a loop of vibratory wave energy. Thus, the phase of vibratory response dilfers conditionally along the length of the armature for high frequencies of this order. This results in decreased efficiency at high frequencies for large transducers of the siZe required in vibration practice. In FIG. 5 the armature is electrically segmentized. Each segment is fed with electrical energy appropriately phased so that the electromagnetic driving force and the vibratory response are in phase throughout the length of the armature.

Accordingly, in the example of FIG. 5

successive segments

82, 83, 84, 85, 86 are of equal length and width and divide the length of the armature into five equal sections. Each of these is fed separately electrically, as from

flexible connections

87, 38, 89, 90, 91. These connections continue to the external electrical circuits through separately insulated conductors in a common bus bar assemblage 92.

The armature is fabricated mechanically as a prestressed structure by tensioned wires 106, shown in FIGS. 5 and 6. A tension of the order of 120,000 pounds per square inch is produced in the Wires. This creates a compressive stress in the segmented aluminum armature of the order of 10,000 pounds per square inch. The maximum stress created by vibration of the armature in use is of the order of 5,000 pounds per square inch, so the armature is always a rigid structure. In practice perhaps 32 wires 6 each one-fourth inch in diameter are used of piano wire material. Only six such wires have been shown in FIG. 5 for sake of clarity. Natural mica, or other insulation suited to high compressive stress, separates the laminations at 105 for necessary electrical insulation.

In FIG. 5 only armature input connections 857 through 91 have been shown for sake of simplicity, but the armature circuit is completed through another set of connections in the manner of either of FIG. 2 or 3. Each pair of connections conveys actuating electrical energy to an armature segment at a different electrical phase. The phase delivered to armature section 86 may be considered zero or reference phase. Since there are five sections in the armature illustrated that phase of electrical energy impressed upon the next section is delayed by external means one-fifth of ninety electrical degrees l8 electrical degrees, at 3,000 cycles. This is 17 microseconds in time. Such a delay is provided by a delay line or by equivalent means in an amplifier feeding this section of the armature. In a similar manner the electrical energy fed to each succeeding

section

84, 83, 82 is delayed 17 microseconds more than the energy feeding each prior section. This technique is understandable from the explanation immediately above; however, details on the external equipment are given in my previously mentioned patent on the four pole transducer.

In the embodiment of FIGS. 5 and 6 the prior shading sheets become shading sections. There is at least one shading section for each armature section. These shading sections are shown at 94 through 103 in FIG. 6. These are insulated, one from the other, and from the field structure 51, to which they are structurally attached.

Connections for the delayed armature feed are given in FIG. 12. The armature sections 82-86 follow FIG. 5 and the shading sections 94-103 follow FIG. 6. Each corresponding group is fed by a separate transformer, as 161 to 165. The initial source of alternating current vibratory energy is connected to terminal 150. Successive delay elements 151-155, such as known delay lines, give successively equal increments of delay to each feed. Amplifiers 156-160 are normally individual power amplifiers each having sufficient output power to energize one out of the groups of armature-shading assemblies shown.

In any of FIGS. 1, 2, 3, 6 alternate arrangements besides those illustrated may be employed for connecting the armature to the shading elements and these to the external circuits. In FIG. 3, for example, flexible armature connecting strips 64- may be directly and independently (as a group) connected to the left side of transformer secondary 58. The shading sheets are connected back upon themselves. That is, connection 63 is retained and a similar connection is made at the left ends of

sheets

55 and 56. This arrangement may be character-ized as the direct armature connection to the electri cal driving means.

As a further alternate the shading sheets, only, may be connected to the driving means and the armature is driven by induction. In this, the

armature connections

59, 64 are connected back on themselves external to the magnetic field and shading sheet connection 63 isconnected to the right-hand side of secondary 58 at 60. With the shading sheet feed the impedance is higher than when the armature is fed alone.

Further considering FIGS. 5 and 6 structurally, elements 107 represent tension adjusting fitments. There are nuts screwed upon the threaded ends of wires 106 and supplied with insulating washers underneath. Each segment of the armature, 82 through 86, must be electrically insulated, one from the other so that the phasing can be accomplished. Each wire is provided with insulation 93 throughout its length and the holes in the several sections of the armature are large enough to accommodate this insulation. The insulation may be provided by dipping each wire in a high quality rubber and then curing the same so that the rubber is bonded to the wire. Suitable it hollow cylindrical tubing of insulating material may also be employed.

In FIG. 7 there is shown a further embodiment of my invention, following the structure of FIG. 6 in a general way. This structure has an electrical impedance much higher than that of the embodiments that have been described.

Numerals Ilt'i, 111, 112 identify characteristic armature laminations, a relatively large number of which are employed, say from 30 to 160 in specific practical applications. These are normally fabricated from aluminum or aluminum alloy. Insulation is provided between each lamination, as at 113, I14, 115. This should be natural mica or another insulator capable of withstanding compressive stress without yielding. A number of tensioned steel strips 116 are employed to bind the laminations into a unified structure. These partake of the general nature of the wires 106 of FIG. but usually half as many are employed as in the case of wires, such as 16 strips 1" wide by 0.1" thick. In FIG. 7 the strips 116 are aligned one behind the other and so only the one at the section can be seen. As with the wires the strips are highly stressed so as to bind the armature into a rigid body under all conditions of vibration.

A tail end plate 117 has the same general shape of a lamination but a greater thickness. Each strip 116 has two hook lugs 118 which fit into suitable notches in tail end plate 117. When a rectangular hole in each lamination and the plate 117 for each strip 116 it will be seen how the rigid body is assembled. Each strip is insulated from each of the laminations by a rubber substance 119 coated on each strip after initial fabrication of the strip. The insulation between laminations, i.e. 113, 114, 115 may have a somewhat smaller rectangular hole than is in the laminations per se and thus each lamination insulator centers the strip away from the metallic laminations.

A head end plate 125 completes the armature structure at the right side of FIG. 7. This has a greater than lamination thickness, as did the opposite tail end plate, but is provided with a round hole in addition to the rectangular slot for each strip. A threaded stud 124 is securely fastened to the top of each strip after the pile of laminations is assembled and then head end plate 125 is attached. A boss 126 is then screwed upon each stud and tightened to provide the tension desired. The boss itself is provided with a slot and central hole so that the specimen to be vibrated or an additional slip table slab can be attached.

The several elements identified by numeral 125) are shading conductors. In the center of the vibratory excursion of the armature (from left to right and vice versa in FIG. 7) each shading conductor is aligned with an armature lamination. These are identified as 131. The armature is shown in its center-of-excursion position in FIG. 7. Immediately opposite to laminations 131 are the shading conductors on the opposite pole face, each identified as 121. While only a group of each of these aligned elements have been identified by the numerals it will be understood that each corresponding element of the whole stack is similarly identified.

Each shading conductor is insulated from every other shading conductor and from the pole face to which it is attached in assembly. This is accomplished by a rubber and fiber-glass bonding particularly between the shading conductors and the pole face. Each shading conductor is spaced a few thousandths of an inch from the ones adjacent to it and at least some of the bonding material fills this space and so sets each shading conductor in an insulating suround. The bonding material is indicated at 122 on upper pole face 123 and at 123 on lower pole face 129. Upper face 123 corresponds to the N pole of FIG. 3 and the lower face to the S pole. In this embodiment it will be seen that the head and tail end plates and the tensioned strips are electrically one, but

this is of no moment because electrical connections of the armature circuit are not made thereto. This arrangement has the advantage of providing a simple and rugged mechanical structure.

The gap between armature and stationary shading conductors is also only of the order of onehundredth of an inch in this embodiment and oil under pressure is preferably used as a suspending medium. In addition, however, I employ a thin sheet of insulation bonded to the armature, either over a restricted area adjacent to the head and tail end plates or over the whole lateral surface of both sides of the armature. This may be Teflon or an equivalent substance and is identified in FIG. 7 as 127. This prevents electrical damage in case of failure of the oil pressure.

FIG. 8 shows how the vibration energizing alternatcurrent is connected to the armature-shading conductor assembly. Only four groups of armature laminations and corresponding top and bottom shading conductors are shown but it Will be understood that the scheme of connection shown embraces all of this assembly.

The scheme of connection is a series one, with each armature lamination connected in series with the two shading conductors associated with it in parallel; those shading conductors connected to the next armature lamination, and so on.

Each group of lamination and shading conductors is shown in perspective so that the connections may be more clearly shown. Each armature lamination is iden tified as 131, each upper shading conductor as 12!) and each lower shading conductor as 1.1; corresponding to the identification in FIG. 7.

An output transformer 1.33 connects between the plate output of a high power audio frequency power amplitier as known in vibration techniques and my transducer. It has approximately the characteristics of the usual such output transformer. The impedance of secondary 135 may be a fraction of an ohm and the impedance of primary 13d of the order of one thousand ohms. The special strap conductor secondary of FIG. 2 is not requireu.

One external circuit connection 136 connects between one side of secondary 135 and the first, or right-hand armature lamination 131. As indicated by the arrow, the instantaneous direction of the current is from back to front of this lamination. Reaching the front the current divides to go to each of the associated shading conductors 126, top, and 121, bottom.

Flexible connections

137 and 133, respectively, establish these conne tions. The current then flows through both of the shading conductors in a direction opposite to the flow through the armature lamination, as will be noted by the arrows. When this traverse has been completed the currents are joined by

flexible connections

139 and 140 and connected to the second armature lamination. Here the fiow from back to front agains occurs, flexible connections again halve the current and pass it to both shading conductors in which it flows back and then through further flexible connections to the next armature lamination, and so on.

After passing through the whole armature-shading assembly the current is joined from the last two shading conductors by stationary connection 141. This, in turn, connects to the opposite side of transformer secondary 135 through connection 142.

Because of this relatively extensive series circuit it will be recognized that the impedance of this assembly is many times greater than the impedance of a solid armature such as in FIG. 2. The structures of FIGS. 7 and 8 are not phased, however, but the construction is employed to obtain a higher impedance than otherwise and so do without very low impedance transformer 7 of FIG. 2.

Still further alternate embodiments are possible.

When the active part of the armature 72 of FIG. 4 is laminated according to FIG. 7, as has been described,

an additional laminated part can be added at the right hand side of FIG. 4, along with a coacting additional field structure 71. This makes a double-ended transducer that is very effective for high power work. The vibrating structure is particularly simple and thus suited for high performance. This alternate embodiment is shown in FIG. 9.

A permanent magnet field element may be employed at 1, 51 or 71 instead of the electromagnet shown. While the toroid shape for the field structure is preferred, this can be of a hollow square shape for FIG. 3 and of a double E shape in FIG. 1.

The fiat plate armatures shown throughout this specification are particularly suited for fastening directly to a specimen or to the slip plate of a slip table. However, a further plate can be bolted to stud holes 46 in FIGS. 1 through 6 or fastened to bosses 12s of FIG. 7, particularly if any of these transducers are to be operated vertically rather than horizontally.

Also, the thus far considered flat plate shape for the armature structures can be made curved, as the arc of a circle. In FIG. 2 or 5, for example, the center of the armature is depressed and the right and left sides are raised above the plane of the paper. The gap in the field structure is correspondingly curved, as an arc replacing the planar aspects of 2 in FIG. 1. In this manner structural strength at extreme lightness can be achieved because of the stiffening of the armature.

These constructions are shown in FIGS. and 11; the former referring to FIG. 3 by reference numerals found therein and provided with primes in FIG. 10, the latter referring to FIG. 4 and similarly identified. The equivalent structure may be employed in FIG. 2 or 5, as has been explained.

In any of the several embodiments it will be appreciated that the flow of oil adjacent to the armature acts to cool it, and the adjacent shading structure.

My novel armature may be characterized as a vane, Whether planar or shaped in a curved surface and whether solid or segmented.

While relatively large and high power transducers have been illustrated and described, my transducer is suitable for miniaturization by merely scaling down all sizes. Other physical modifications may be made in the arrangement, proportions and combinations of the several embodiments given. Other electrical modifications may be made in the characteristics of the circuit elements, the coactive relation between such elements and details of circuit connection without departing from my invention.

Having thus fully described my invention and the manner in which it is to be practiced, I claim:

1. An electromechanical transducer comprising only one electrically conductive vane,

means to impress a magnetic field transversely through the thickness of all of said vane,

and plural flexible connection means to pass an electric current across said vane for motional excitation thereof.

2. An electrical to mechanical transducer comprising only one segmented conductive plate,

means to impress a magnetic field transversely through the thickness of all of said plate,

and means to pass an electric current through the segments of said plate at right angles to said magnetic field for motional excitation of said plate.

3. An electromechanical transducer comprising only one flat electrically conductive horizontally disposed armature having two lateral surfaces,

means to impress a uniform magnetic field perpendicularly through substantially all of the area of said lateral surfaces of said armature,

and multiple flexible connection means to pass an alternating current in the direction of a major di- 1h mension of said armature for the motional excitation thereof.

4. An electromechanical transducer comprising only one electrically conductive vane of non-magnetic material,

a laterally disposed magnetic structure coextensive with said vane and having a pole facing each side of said vane,

plural groups of external conductors, each said group having plural conductors connected to an edge of said vane and to an external source of current to mechanically move said vane,

and fluid means under said vane to position said vane in relation to said magnetic field structure to allow motion of said vane relative to said magnetic field structure.

5. An electro-dynamic shaker comprising only one transversely electrically conductive plate-like armature having greater conductivity in one direction than in another,

a magnetic field structure having one pole face directly abutting each side of said armature,

an electrical conductor mounted on at least one said pole face,

external conductors connecting one edge of said armature to an adjacent end of said electrical conductor,

further external conductors connecting another edge of said armature and another end of said electrical conductor to an external source of electric current to energize said armature,

and liquid means to laterally position said armature within said field structure for the free vibration of said armature.

6. An electrical to mechanical transducer comprising only one electrically conductive flat armature,

a stationary magnetic field structure having one pole face directly abutting each lateral surface of said armature,

at least one insulated shading conductor for reducing inductance mounted on each said pole face adjacent to said armature,

external conductors connecting one edge of said armature to the adjacent ends of said shading conductors,

further external conductors connecting the opposite edge of said armature and the opposite ends of said shading conductors to an external source of alternating current to vibrate said armature,

and liquid pressure means to laterally position said armature within said field structure for the free vibration of said armature transversely with respect to the magnetic field impressed upon said armature by said magnetic field structure.

7. An electromechanical shaker comprising a conductive vane armature,

a bi-toroidal field structure having a central gap to completely enclose said armature,

at least one coil upon a toroid of said field structure to produce a magnetic field across said central gap disposed with the plane of said coil angularly removed from the direction of maximum dimension of said armature,

openings in a field toroid adjacent to said armature,

connectors attached to said armature and passing through said openings to external electrical circuit means for energizing said armature,

a conductor attached to each side of said gap in said field structure adjacent to said armature,

connections from each of said conductors to said armature,

and connectors attached to said conductors adjacent to said openings and passing from said field toroid at the ends of the central hole thereof to said external electrical circuit means.

8. An electrical to mechanical transducer comprising an electrically conductive pirate-shaped armature of non-magnetic material,

a bi-toroidal field structure having a common central gap to completely laterally enclose said armature,

a toroidal coil surrounding each toroid of said field structure to produce a magnetic field therein,

the plane of at least one said toroidal coil angularly removed from the plane of said armature,

ducts in the plane of said armature in that field toriod having said coil angularly removed,

flexible connectors attached to an edge of said armature and passing hrough said ducts to external electrical circuit means for energizing said armature,

a shading conductive sheet insulatingly attached to each side of said central gap of said field structure adjacent said armature,

electrical connections from each of said sheets to the edge of said armature opposite said prior edge,

connectors attached to the ends of said shading sheets adjacent to said ducts and passing from the field toroid at the ends of the central aperture thereof to said external electrical circuit means,

holes in said bi-toroidal field structure through said shading sheets,

and means to force fluid under pressure through said holes to support said armature for movement with respect to said field structure.

9. An electromechanical transducer comprising only one vane-like armature,

a circular magnetic field structure having a radial opening to mechanically accommodate the minimum dimension of said armature,

means to produce a magnetic field across opening,

a conductor upon each pole face of said opening adjacent to said armature,

a fiexible connection between said conductor and said armature at the smallest radius of said circular field structure,

a transformer Winding,

flexible connections between said transformer winding and said armature at the largest radius of said field structure,

and another connection between said transformer winding and said conductors to complete an electrical circuit for the excitation of said armature.

10. The transducer of claim 9 in which said vane-like armature has the form of a curved surface in one dimension and the direction of said magnetic field and the location of said flexible connections are such as to cause motion in a dimension perpendicular to that of said curved surface.

11. An electrical to mechanical transducer comprising an electrically conductive fiat plate-like armature,

a toroidal magnetic field structure having one radial gap to accommodate said armature,

a field coil toroidally wound around said field structure to magnetize the same,

an insulated shading conductor upon each pole face of said gap closely adjacent to said armature,

flexible connections between said shading conductor and the edge of said armature at the smallest radius of said toroidal field structure,

a low impedance transformer winding,

flexible connections between one terminal of said transformer winding and the edge of said armature at the largest radius of said toroidal field structure,

a connection between the other terminal of said transformer winding and said shading conductors on each said pole face,

and fluid pressure means to position said armature within the gap in said field structure for the free motion of said armature with respect to said field upon both said armature and said field being energized with electric current.

said

12. The transducer of claim 11 in which two low impedance windings of said transformer are connected in parallel to said armature and said shading conductors.

13. An electromechanical vibrative device comprising a magnetic field structure having pole pieces,

an electrically conductive armature having the shape of a small segment of a cylindrical surface disposed between and extending beyond said pole pieces,

a member of large inertia supporting said extended part of said armature,

flexible means connected to said armature for passing current through the same,

and means upon said extended part to fasten a specimen to said armature.

14-. An electrical to mechanical transducer comprising a magnetic field structure having a single horizontally disposed planar gap,

a single electrically-conductive non-magnetic flat platelike armature disposed within said gap and extending beyond it in one direction,

flexible connection means connected to said armature for passing electric current through that portion of said armature disposed within said gap,

a member of large inertia supporting the extended portion of said armature,

a lubricant between said member and said armature,

a common base for said field structure and said member,

and means upon the extended part of said armature to attach a specimen to be vibrated directly to said armature.

15. An electrical to mechanical transducer comprising two spaced magnetic field structures each having a single horizontally disposed gap,

an electrically conductive flat plate armature extending between said field structures and disposed within said gap of each,

electrical connection means connected between said armature and a stationary source of electric current,

and one member of large inertia supporting said armature.

16. The transducer of claim 15 in which the parts of said armature disposed within said gaps are laminated transversely of the length of said armature.

17. The transducer of claim 15 in which the parts of said armature disposed within said gaps are laminated, stationary shading conductors are aligned with said laminations and the laminated parts of said armature are electrically interconnected with adjacent said shading conductors for the vibrational excitation of said armature.

18. In an electromechanical transducer having an elongated fiat armature and a field structure for impressing a magnetic field transversely through said armature, means for establishing electrical connection to said armature through said field structure compromising plural conductors disposed along said armature and plural slots in said field structure for passing said conductors through said field structure, said field structure formed of increased external size adjacent to said slots to maintain the cross-section of said field structure substantially the same as the cross-section away from said slots.

19. In an electromechanical transducer having an armature and a single slot field structure for impressing a magnetic field transversely through said armature, means for establishing electrical connection to said armature comprising plural flexible strip conductors disposed along said armature, plural slots in said field structure for passing said conductors through said field structure, and insulation lining each said slot to insulate said conductors from said field structure.

20. The connection means of claim 19 in which said armature is sectionalized and each said flexible strip connects one section thereof to separate phase-related circuits.

21. The connection means of claim 19 in which each said flexible strip is comprised of plural conductive ribbons and the depth of said insulated slots is such as to clamp the ribbon strips Within said slots.

22. In an electromechanical transducer having a planar armature and a field structure for impressing a magnetic field transversely through said planar armature, means for establishing external electrical connection to said planar armature comprising a plurality of flexible strip conductors disposed along an edge of said plate, the same plurality of said slots in said field structure adjacent to said conductors for passing said conductors through said field structure to external electrical connections, there being one said conductor in each one said slot, and insulation lining each said slot to insulate said conductors from said field structure.

23. An electromechanical device comprising a plurality of elongated conductive armature sections disposed in an aligned stack plural members in tension insulatingly disposed within said armature to hold said sections together, field pole faces laterally adjacent to said armature, magnetomotive force means to pass magnetic flux through said pole faces and through said armature,

the same plurality of conductor sections fastened to said pole faces in alignment with said armature sections,

means to electrically connect each group of said aligned armature sections and each corresponding said conductor section,

means to pass electric current through at least one of said armature and said conductor sections in each said group,

a connection from each said means to each corresponding said armature each conductor section,

and means to delay the electric current through each said armature and conductor section corresponding to the time for propagation of a mechanical Wave along said stacked armature.

24. An electrical to mechanical transducer comprising a plurality of separately-insulated conductive armature sections stacked in a structurally unified plate-like assembly,

one field pole face adjacent to each side of said armature stack,

means to form magnetic poles of opposite polarity on opposite said field pole faces,

the same plurality of separately-insulated shading sections attached to said pole faces in lateral alignment with said armature sections and closely adjacent thereto,

said armature sections electrically connected to each said shading section having the same relative position as the particular armature section,

the same plurality of means to pass an electric current through said armature and said shading sections,

one connection from each said means to each corresponding said armature and shading section,

and means to delay in time the electric current through each said armature and shading section corresponding to the time for propagation of a mechanical impulse along said stacked armature.

25. An electrical to mechanical transducer comprising a plurality of separately-insulated conductive armature sections disposed in a congruent stack,

insulated tensioned elements attached thereto to compress said stack,

pole faces adjacent to each side of said armature stack,

means to form magnetic poles of opposite polarity on opposite sides of said armature stack,

the same plurality of separately-insulated shading sections attached to each said pole face in alignment with said armature sections and closely adjacent thereto,

each said armature section electrically connected to each said shading section having the same relative position as the said armature section,

and means to pass an electric current through all said armature and said shading sections.

26. An electromechanical transducer comprising a plurality of stacked separately-insulated non-magnetic conductive armature segments each having plural aligned central apertures,

a strip of high tensile strength material passing through an aligned aperture in each said segment.

means to insulate each said strip from each said aperture,

plates to compress said stacked segments,

means to exert a tension upon each said strip greater than any tension induced in said strip by mechanical stress of the transducing process to compress said stacked segments by means of said plates,

means to pass a magnetic field through each of said armature segments,

the same plurality of separately-insulated stationary shading conductors disposed adjacent to said armature segments,

means to successively electrically connect each said armature segment to adjacent said shading conductors,

and further means to connect the first of said armature segments and the last of said shading conductors to an energizing electrical circuit.

27. An electromechanical transducer comprising plural separate conductive armature segments,

tensioned members attached to said segments to form a rigid vane-like armature structure,

means to pass a magnetic field through each of said armature segments,

the same plurality of insulated shading conductors disposed adjacent to said armature segments on each side thereof and attached to said means to pass a magnetic field,

means to electrically energize said armature for vibration,

conductive means to connect one end of the first of said plural armature segments to said means-to-energize,

conductive means to connect the opposite end of said first armature segment to one end of each of the first of said shading conductors,

conductive means to connect the opposite ends of each of said first shading conductors to one end of the second of said armature segments,

conductive means to connect the other end of said second armature segment to one end of each of the second of said shading conductors,

and further said conductive means to connect successive said plurality of armature segments and corresponding pairs of said plurality of shading conductors,

and final conductive means to connect the last of said pairs of shading conductors to said means-to-energize to complete the electrical circuit,

28. An electrical to mechanical transducer comprising a large plurality of separately-insulated non-magnetic linear conductive armature segments having aligned apertures,

strips of high tensile strength material passing through said aligned apertures,

means to insulate each said strip from each said aperture,

means to exert a tension upon each said strip greater than any tension caused in said strip by the mechanical eifect of the transducing process,

means to pass a magnetic field through each of said armature segments perpendicular to the alignment of said apertures,

the same plurality of separately-insulated shading conductors disposed adjacent to said armature segments on each side thereof upon said means to pass a magnetic field,

alternating-current means to electrically energize said armature for vibration,

flexible means to connect one end of the first of said plural armature segments to said alternating-current means,

flexible means to connect the opposite end of said first armature segment to one end of each of the first said shading conductors,

flexible means to connect the opposite ends of each of said first shading conductors to one end of the second of said armature segments,

flexible means to connect the other end of said second armature segment to one end of each of the second of said shading conductors,

and further said flexible means to connect said plurality of armature segments and corresponding pairs of said plurality of shading conductors,

final conductive means to connect the last of said pairs of shading conductors to said alternating-current means to complete a series electrical circuit,

and fluid pressure means to position said armature for motion with respect to said shading conductors.

References Cited in the file of this patent UNITED STATES PATENTS Re. 24,816 Woods Apr. 26, 1960 1,266,988 Pridham May 21, 1918 1,589,019 Purser June 15, 1926 1,672,351 Thomas June 5, 1928 1,682,866 Thomas Sept. 4, 1928 2,053,619 Le Golf Sept. 8, 1936 2,134,510 Hague Oct. 25, 1938 3,004,180 Macks Oct. 10, 1961

Claims

1. AN ELECTROMECHANICAL TRANSDUCER COMPRISING ONLY ONE ELECTRICALLY CONDUCTIVE VANE, MEANS TO IMPRESS A MAGNETIC FIELD TRANSVERSELY THROUGH THE THICKNESS OF ALL OF SAID VANE, AND PLURAL FLEXIBLE CONNECTION MEANS TO PASS AN ELECTRIC CURRENT ACROSS SAID VANE FOR MOTIONAL EXCITATION THEREOF.