US3878487A - Electromechanical disc filter - Google Patents

Electromechanical disc filter Download PDF

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Publication number
US3878487A
US3878487A US384977A US38497773A US3878487A US 3878487 A US3878487 A US 3878487A US 384977 A US384977 A US 384977A US 38497773 A US38497773 A US 38497773A US 3878487 A US3878487 A US 3878487A
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disc
resonators
resonator
mechanical links
electromechanical
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US384977A
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Alexandr Lvovich Irzhavsky
Petr Samuilovich Stolyar
Konstantin Alexandrovi Shulgin
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/62—Filters comprising resonators of magnetostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/48—Coupling means therefor
    • H03H9/50—Mechanical coupling means

Definitions

  • the invention relates to frequency selection apparatus incorporating as their basic selective components high-quality mechanical resonators mechanically connected to one another and. more particularly. to electromechanical filters.
  • Electromechanical filters are characterized by high selectivity and thermal stability. as well as by being fit for incorporation in narrow-band filters.
  • Electromechanical filters can be employed in a vast range of radio and electronic apparatus where selection of a frequency signal is needed. Thus. they may be incorporated in communication systems. in radar installations. in measuring circuits. etc.
  • An electromechanical filter per se is an apparatus comprising an input electromechanical transducer and an output electromechanical transducer. such as magnetostriction. piezoelectric and other transducers. and a mechanical resonance system including. depending on the required selectivity. an adequate plurality of mechanical resonators. e.g. metal resonators interconnected with metal links such as wires. bands. cylinders.
  • electromechanical filters with either axial or parallel arrangement of cylinder-shaped resonators operable in a torsional oscillation mode.
  • Electromechanical filters with torsional oscillation have found application in a frequency range from 60 to 300 kHz.
  • a modification of these filters with axial arrangement of the resonators has relatively great length.
  • the length ofa five-to six-resonator filter rated for operating frequencies of about 100 kHz is a great as ISO to 160 mm.
  • Filters of this last type which are relatively narrow-band ones 1 percent) have to have their mechanical strength enhanced by complicated coupling of the resonators. which structurally leads to an even greater length of the filter.
  • a torsional oscillation filter with parallel arrangement of the resonators has a considerably smaller longitudinal dimension than the one having axially extending resonators; however. the overall volume of the former does not differ considerably from that of a similar filter with the axial arrangement.
  • Plate-type filters are employed for operation at frequencies of about 400 to 600 kHz. These filters, however. being highly promising from the point of view of miniaturization of electromechanical filters. have not conquered the field on account on intensive side pass bands inherent in such filters. owing to the presence of densely located resonances of bending oscillation in the thin plates.
  • Electromechanical disc filters are used with operating frequencies with a 60 to 600 kHz range.
  • the most commonly used structure of an electromechanical disc filter has peripherally arranged longitudinally oscillating linking elements.
  • a major disadvantage offilters of this structure is their relatively great size.
  • electromechanical disc filters marketed by the Collins Company and rated for 60 to 108 kHz have an overall volume of about 80 cu.cm.
  • the disc filters rated for a relative bandpass below 0.5 percent necessitate the incorporation of complicated coupling or linking means between the resonators. which increases the length of these filters.
  • a reduction in the size of electromechanical disc filters with peripheral linking elements is liable to affect both the mono-frequency characteristics of a filter and its mechanical strength. The reason is as follows. With a reduction in the size of disc resonators. there takes place. across their entire surface. including their peripheries. a reduction of the impedance to the main oscillation with nodal circles. as well as to'side oscillations with their nodal diameters. Simultaneously there is a substantial narrowingof the gap between the resonance frequencies of the side modes of oscillation with nodal diameters and the frequencies with nodal circles; To compensate for this reduction of the impedance values of the resonators and thus maintain the desired bandpass. it is necessary to reduce considerably the diameter of the wire linking elements.
  • lt is also an object of the present invention to create such structures of electromechanical filters which should solve the problem of creating miniature monofrequency filters of adequate mechanical strength having various pass bands within a broad range of frequencies.
  • an electromechanical disc filter comprising an input electromechanical transducer. a plurality of disc resonators arranged parallel to one another in spaced relationship and operable in a bending oscillation mode with nodal circles. said disc resonators including at least one intermediate disc and a pair of terminal discs. interconnected with longitudinally extending mechanical links. and an output electromechanical transducer. in which filter. in accordance with the present invention. said mechanical links are attached to the face surfaces of said disc resonators at points placed along a circle having the diameter equal to that of a nodal circle ofsaid disc resonator.
  • an electromechanical filter wherein said disc resonators are operable in a bending oscillation mode with a single nodal circle should have said mechanical links thereof. interconnecting adjacent pairs of said disc resonators. attached to the face surfaces of each said respective disc resonator at points placed along a circle having a diameter equal to about 0.68 of the external diameter of said disc resonator.
  • an electromechanical filter wherein said disc resonators are operable in a bending oscillation mode with two nodal circles. should have said mechanical links thereof. interconnecting adjacent pairs of said disc resonators. attached to the face surfaces of each said respective disc resonator at points placed along a circle having a diameter equal to about 0.82 ofthe external diameter of said disc. Furthermore.
  • said mechanical links should be in this case additionally attached to the face surfaces of said disc resonators at points placed along a circle having a diameter equal to about 0.36 of said external diameter of said disc.
  • the present invention also envisages various structures of resonator systems in one of which said disc resonators interconnected with thin mechanical links are arranged in a stepwise fashion. so that said mechanical links of each intermediate one of said resonators are attached to but one face of said intermediate disc resonator. said mechanical links being disposed to one side of said intermediate disc resonator. whereas each said terminal disc resonator has said mechanical links attached to both face su rfaces thereof. connecting it at one side to the intermediate disc resonator and at the other side. to a support member.
  • said mechanical links interconnecting said disc resonators are arranged so that the respective diametral planes of said discs. including the axes of said respective mechanical links of any adjacent pair of said discs intersect at an angle (1 within a 90 to 180 range.
  • the present invention further envisages a struc ture of the resonator system. wherein said intermediate disc resonators are arranged coaxially and make up at least two sections. said sections being interconnected by a disc resonator so that said two sections are disposed to one side of said interconnecting disc resona- I01.
  • the present invention envisages a resonator system wherein at least two said disc resonators from the total plurality of said disc resonators. interconnected with said mechanical links attached to the face surfaces of said disc resonators at points corresponding to the nodal circles. have different geometrical dimensions. all said disc resonators being tuned to the same frequency for oscillation with the nodal circles. said resonators with different geometrical dimensions having different frequencies of side oscillation.
  • FIG. I shows an electromechanical disc filter. according to the invention.
  • FIG. 2 is a view taken along line llll of FIG. I;
  • FIG. 3 illustrates the resonator system of an electromechanical disc filter. according to the invention
  • FIG. 4 shows the disc resonator operating in a bending oscillation mode with a single nodal circle
  • FIG. 4a is a diagram of distribution of the normal component of velocity V,, at the end surface of the resonator along its radius;
  • FIG. 4b shows a diagram of distribution of impedances 2,, at the end surface of the resonator along its radius
  • FIG. 4c shows a diagram of distribution of the tangential (radial) component of velocity V at the end surface of the resonator along its radius
  • FIG. 441 shows a diagram of distribution of impedances Z at the end surface of the resonator along its radius
  • FIG. 5 shows the disc resonator operating in a bending oscillation mode with two nodal circles
  • FIG. 5a shows a diagram of distribution of the normal component of velocity V,, at the end surface of the resonator along its radius
  • FIG. 5b shows a diagram of distribution of impedances 2,, at the end surface of the resonator along its radius
  • FIG. 50 shows a diagram of distribution of the tangential (radial) component of velocity V at the end surface of the resonator along its radius:
  • FIG. 5d shows a diagram of distribution of impedances Z at the end surface of the resonator along its radius
  • FIG. 6 shows a resonator system comprising two disc resonators interconnected with peripheral mechanical links
  • FIG. 6a shows the passage of a signal through a system comprising two disc resonators with peripheral mechanical links at the resonance frequencies of oscillation with nodal circles and nodal diameters;
  • FIG. 7 shows a resonator system comprising two disc resonators interconnected with mechanical links in accordance with the present invention
  • FIG. 7a shows the passage of a signal through a system constructed in accordance with the present invention. at the resonance frequencies of oscillation with nodal circles and nodal diameters.
  • FIG. 8 illustrates another embodiment of the resonator system of an electromechanical disc filter. according to the invention.
  • FIG. 9 is a top view of the system illustrated in FIG. 8.
  • FIG. 10 illustrates still another embodiment of the resonator system of an electromechanical disc filter. according to the invention.
  • FIG. 11 is a top view of the system illustrated in FIG. 10:
  • FIG. 12 illustrates the resonator system shown in FIG. 8. additionally including rejector resonators:
  • FIG. 13 illustrates a resonator system comprising two sections of resonators: y 7
  • FIG. 14 illustrates a resonator system wherein the resonators have different geometrical dimensions.
  • FIG. I An electromechanical disc filter constructed in accordance with the present invention is illustrated in FIG. I. It comprises a resonator system I which is the major functional part of the structure of the filter. as well as several attachment and fixture items. such as shows absorbing rubber supports 2. spacers 3. a base 4 with leads 5 soldered thereto and a screen 6 the above items being intended for positioning the resonator system l. for damping its vibration. for its hermetization. for supply and output of electric power and for protecting the system from external mechanical influences.
  • a resonator system I which is the major functional part of the structure of the filter. as well as several attachment and fixture items. such as shows absorbing rubber supports 2. spacers 3. a base 4 with leads 5 soldered thereto and a screen 6 the above items being intended for positioning the resonator system l. for damping its vibration. for its hermetization. for supply and output of electric power and for protecting the system from external mechanical influences.
  • the electromechanical filter includes inductance coils 7 and permanent magnets 8 (FIG. 2) which are elements of a functionally complete electromechanical transducer assembly.
  • the present invention and the advantages thereof are connected with the improvements in the structure of the resonator systems of electromechanical disc filters. Therefore. the following disclosure is going to dwell primarily on the features pertaining to the construction of the resonator systems.
  • This resonator system 1 includes an array of intermediate disc resonators 9, a pair of terminal disc resonators I0. mechanical links 11 and metal magnetostrictive rods 12.
  • the mechanical links ll serve to attach the terminal disc resonators 10 to the respective support sleeves 13 by means of which the resonator system 1 (FIG. I) is mounted in the shock absorbing supports 2;
  • the sleeves 13 receive thereinside the inductance coils 7 (FIG. I). while the permanent magnets 8 are mounted externally of the sleeves 13.
  • FIG. 4a Illustrated in FIG. 4a is a disc resonator and one of the extreme positions thereof when bending oscillation with a single nodal circle is excited in the disc.
  • the diagrams in FIGS. 4b and 4d show the distribution of the normal component V, and tangential component V, of the velocities of the points on the face surface of the disc resonator along the radius thereof.
  • FIGS. 4(- and 4e illustrate the distribution of the respective components 2,, and Z, of the impedance at the same points of the disc resonator. It is seen from the FIGS. 4a. b. c. d. e that when oscillation with a single nodal circle is excited in the disc.
  • the coupling factor between disc resonators. as well as the band pass of the filter. are proportional to the ratio of the wave resistance of the mechanical links to the impedance values of the disc resonator at points of attachment of the mechanical links.
  • the above fact relates the width of the band pass of an electromechanical disc filter to the mechanical strength of the resonator system thereof. It can be understood that in order to have a relatively narrowbandpass electromechanical disc filter. it is necessary to reduce the wave resistance of its mechanical links. which can be attained by reducing the cross-sectional area of these mechanical links. i.e.. by reducing the mechanical strength of the resonator system. It is this fact that brings about the necessity of introducing additional untuned resonators into the structure of the hitherto known electromechanical disc filters with peripheral arrangement of the mechanical links.
  • the impedance values Z are infinite. i.e.. the disc resonators exhibit infinite resistance to longitudinal oscillation in the mechanical links. when they oscillate in a mode with nodal circles. It is also seen from FIGS. 4 and 5 that the impedance values Z, at the points a, b. c are considerably greater than the imped ance values 2,, at the periphery of the disc. Besides. the wave resistance of the wire rods of which the mechanical links are made to bending oscillation is considerably lower than their resistance to longitudinal oscillation.
  • Another characteristic feature of the proposed structure of resonator systems is that it makes it possible to eliminate practically completely the side bandpasses present at the resonance frequency of bending oscillation with nodal diameters.
  • the resonance frequencies of this type of oscillation of the two adjacent orders are. as a rule. close to the resonance frequency of oscillation with nodal circles (i.e.. the useful oscillation) and. therefore. are the most unwanted.
  • the frequency gap between the resonance frequencies of oscillation with nodal circles and that with nodal diameters is usually small and depends on the ratio of the diameter of the disc resonator to the thickness thereof. With the ratio of the diameter of the disc to its thickness increasing. the gap between the said resonance frequencies narrows.
  • a characteristic feature of these novel structures is an arrangement of the resonators and their mechanical links. wherein either one or several discs of the resonator system have the mechanical links attached to but one of the face surfaces thereof.
  • One of the embodiments of such a resonator system is illustrated in FIGS. 8 and 9 of the appended drawings.
  • the disc resonators l4 and 15 are interconnected with a single mechanical link 16.
  • the support sleeves are connected to the discs IS with mechanical links 18.
  • the same face surface of the discs 15 is associated with the magnetostrictive rods 19 of the.
  • the value of the coupling factor between two adjacent resonators depends on the orientation of the said diametral planes of these two adjacent discs relative to each other. i.e.. on the value the angle When 0: equals l the structure is. as shown in FIGS. 8 and 9.
  • the coupling factor diminishes with the reduction of this angle a.
  • electromechanical disc filters which. although being of the same mechanical strength. would feature different bandpass widths. from very narrow ones to relatively broad ones.
  • FIG. 13 of the appended drawings presents an embodiment of a resonator system. in accordance with the invention. which is preferable to be employed in electromechanical disc filters of particularly high selectivity.
  • the resonator system is made up by individual sections wherein in each section the resonators 21 are arranged coaxially and parallel to each other.
  • the mechanical links 22 are attached to both surf-aces of each resonator 21.
  • the two sections are interconnected by a resonator 23 with the help of mechanical links 24 attached to but one face surface of the last-mentioned resonator.
  • the unoccupied face surface of this disc resonator 23 is used to attach it toan additional support 25. Alternatively. this face surface. as well as the unoccupied face surfaces of the discs 21 of the two sections may be used for mounting thereon rejector resonators.
  • FIG. 14 of the appended drawings shows a disc resonator system wherein disc resonators 26 have geometrical dimensions that are different from those of disc resonator 27. all the disc resonators of the system being tuned to the same frequency of the main type of oscillation. i.e.. of oscillation with nodal circles and untuned to the side frequencies.
  • This structure of a resonator system is particularly suitable for incorporation in electromechanical disc filters featuring an increased degree of suppression of side oscillation.
  • a 5 9 resonator system constructed in accordance with the present invention and rated for mean frequency of I kHz bandpass has a volume. respectively. 3.5 cu.cm to 5.0 cu.cm; similar filters rated for mean frequency 500 kHz have respective volumes from L cu.cm to 2.0 cu.cm.
  • Electromechanical filters incorporating the resonator systems herein disclosed have relatively high mechanical strength. They have been found to withstand without altering their parameters. vibration loading within a range of vibration frequency up to 2.000 Hz with acceleration up to g. as well as repeated impacts with g acceleration and single impacts with g acceleration.
  • .l.-An electromechanical disc filter comprising: an inputelectromechanical transducer; a plurality of disc resonators arranged parallel to one another in spaced relationship and operable in a bending oscillation mode "with nodal circles. said plurality including at least one intermediate disc resonator and a pair of terminal disc resonators; longitudinally extending mechanical links interconnecting said disc resonators.
  • said mechanical links being attached to the face surfaces of the respective ones of said disc resonators at points along a 'circle having a diameter equal to the diameter of a nodal circle of said disc resonator; support elements for mounting said terminal disc resonators; an output electromechanical transducer said disc resonators being arranged in a stepwise fashion; those of said mechanical links that are associated with each said intermediate disc resonator being attached to but one face surface thereof.
  • said mechanical links being situated to one side of said intermediate disc resonator: each said terminal disc resonator having said mechanical links attached to both face surfaces thereof. said last-mentioned mechanical links at one side of said terminal disc resonator connecting it with the adjacent one of said intermediate disc resonators and at the other side thereof connecting it to the respective one of said support elements.
  • An electromechanical disc filter as claimed in claim 1 wherein said mechanical links interconnecting said intermediate disc resonator and terminal disc resonators are parallel to one another and are so arranged that the diametral planes of said discs including the axes of the respective ones of said mechanical links of any two adjacent ones of said discs of said resonatory system intersect at an angle a within a range from 90to 3.
  • An electromechanical disc filter as claimed in claim I wherein at least one of said disc resonators has attached to the unoccupied face surface thereof a rejector resonator so that said rejector resonator creates an attenuation pole.
  • An electromechanical disc filter comprising: an input electromechanical transducer; a plurality of disc resonators operable in a bending oscillation mode with nodal circles. said plurality including at least one intermediate disc resonator and a pair of terminal disc resonators; mechanical links interconnecting said disc resonators; an output electromechanical transducer; said mechanical links being attached to the face surfaces of the respective ones of said disc resonators at points thereof along a circle having a diameter equal to the diameter of a nodal circle of said disc resonator: at least two of said plurality of disc resonators having different geometrical dimensions; all said disc resonators being tuned to the same frequency of oscillation withnodal circles; said disc resonators having different geometrical dimensions being tuned to different frequencies of side oscillation.
  • An electromechanical disc filter comprising: an input electromechanical transducer: a plurality of disc resonators arranged parallel to one another in spaced relationship and operable in a bending oscillation mode with a single nodal circle. said plurality including at least one intermediate disc resonator and a pair of terminal disc resonators: longitudinally extending mechanical links interconnecting said disc resonators. said mechanical links being attached to the face surfaces of said disc resonators at points making only tangentialradial and angular motion and disposed along a circle having a diameter equal to 0.68 of the external diameter of said disc resonator.
  • An electromechanical disc resonator comprising: an input electromechanical transducer: a plurality of disc resonators arranged parallel to one another and operable in a bending oscillation mode with two nodal circles. said plurality comprising at least one intermediate disc resonator and a pair of terminal disc resonators: longitudinally extending mechanical links interconnecting said disc resonators. said mechanical links being attached to the face surfaces of said disc resonators at points making only tangential-radial and angular motion and disposed along a circle having a diameter equal to 0.82 of the external diameter of said disc reso nator.
  • An electromechanical disc filter comprising: an input electromechanical transducer: a plurality of disc resonators arranged parallel to one another and operable in a bending oscillation mode with two nodal circles. said plurality comprising at least one intermediate disc resonator and a pair of terminal disc resonators; longitudinally extending mechanical links interconnecting said disc resonators. said mechanical links being attached to the face surfaces of disc resonators at points making only tangential-radial and angular motion and disposed along a circle having a diameter equal to 0.36 of the external diameter of said disc reso-

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  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
US384977A 1973-08-02 1973-08-02 Electromechanical disc filter Expired - Lifetime US3878487A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080086016A1 (en) * 2003-05-29 2008-04-10 New River Pharmaceuticals Inc. Abuse resistant lysine amphetamine compounds

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2453122A1 (de) * 1974-11-08 1976-05-20 Siemens Ag Filter fuer elektrische schwingungen

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2615981A (en) * 1949-01-14 1952-10-28 Collins Radio Co Electromechanical filter
US3351875A (en) * 1962-12-20 1967-11-07 Collins Radio Co Ring coupled mechanical filter

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2615981A (en) * 1949-01-14 1952-10-28 Collins Radio Co Electromechanical filter
US3351875A (en) * 1962-12-20 1967-11-07 Collins Radio Co Ring coupled mechanical filter

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080086016A1 (en) * 2003-05-29 2008-04-10 New River Pharmaceuticals Inc. Abuse resistant lysine amphetamine compounds

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FR2242815B1 (enrdf_load_stackoverflow) 1976-10-01

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