US1834875A - Acoustic testing apparatus for detecting irregularities of machines of any type - Google Patents

Acoustic testing apparatus for detecting irregularities of machines of any type Download PDF

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Publication number
US1834875A
US1834875A US487085A US48708530A US1834875A US 1834875 A US1834875 A US 1834875A US 487085 A US487085 A US 487085A US 48708530 A US48708530 A US 48708530A US 1834875 A US1834875 A US 1834875A
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Prior art keywords
resonator
box
sound
machines
type
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Expired - Lifetime
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US487085A
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English (en)
Inventor
Schaafhausen Wilhelm
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"HEROLD" AG
HEROLD AG
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HEROLD AG
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
    • G10K11/04—Acoustic filters ; Acoustic resonators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid

Definitions

  • HAMBURG wrmmI-u scnzAArnAusnn
  • HAMBURG GERMANY, Assrenoza 'ro EEBOLD AKTIENGESELLSOEAI'T
  • HAMBURG ennmm- I Acousrro rnsrme ArrAaA'rUs ron nnmo'rme mnEeULAnrrms or or ANY ma Application med October 7, 1930, serial No.
  • My invention relates to improvements in acoustic testing apparatus for detecting irregularities of machines of any type.
  • testing apparatus have been 5 used in which the acoustic vibrations of machines are transmitted through a hollow or solid rod to adiaphragm for rendering the same audible, so that the irregularities and the source-thereof may be ascertained by the abnormal tones.
  • Apparatus of this type are objectionable for the reason that all the noises caused by the machine are transmitted to the ear, sothat it is-frequentlydiflicult to find out the abnormal tones and their source, 1 the intensity of the said tones being ordinarily very small.
  • the object of the improvements is to provide a system in which this objection is obviated.
  • the resonators proposed by Helmholtz re- 90 produce a certain fundamental tone depending on the size of the apparatus, and in addition very high overtones. If the fundamental tone of a resonator of this type is transmitted, the air of the resonator is made to resound, 2! and the sound thus intensified is directly transmitted to'the ear of the attendant bearing on the resonator, while other flmdamental tones are not perceived. If the other ear of the attendant is closed the said foreign fundamental'tones are not perceived at all.
  • the attendant perceives only those tones of the noises of the 85 machine the vibrations of which correspond to the vibrations of the resonator.
  • the individual tone of the noise of the machine may be isolated.
  • the whole noise of the machine may be subdivided into tones of different oscillations, and finally the tone may be isolatedwhich is to be specifically ban gated as to its character and its source.
  • the cavity of which may be en larged or reduced in size so as to vary the fundamental tone of the resonator.
  • the size of the cavity may be varied by tubular member having an opening f for the uAcmn'Es 487,085, and in Germany August 20, 1929.
  • a resonator of this type may be tuned; by
  • Another object of the improvements is to provide a system in which the resonator and the testing device are combined into a single apparatus, which is simple in construction. Further the resonator may be constructed so that asingle apparatus comprises several octaves.
  • Fig. 1 is a sectional elevationshowing a resonator adapted to be connected with the receiver of an acoustic testing device, and
  • Fig. 2 is a sectional elevation showing an acoustic testing apparatus combined with a. resonator.
  • a is the receiver of the acoustic testing -ap- .paratus and b-the diaphragm thereof.
  • a is the outer cylindrical wall of the Helm holtz resonator having anopening d for the admission of the sound.
  • e is a tubular member in telescoping engagement with the cylindrical wall, the said delivery of the sound.
  • the said tubular member is held with its opening 7 on the ear.
  • the testing apparatus as 1 may be omitted and the resonator may be directly-placed on the machine to be tested.
  • the use of the resonator, which'may 'or may/not be provided with a testing ap pa atus, isnot limited to machines, and it may be used whereverit is desired to isolate 'and test tones.
  • Fig. 2 1 is the outer box having a'lid 4 and a bottom 2 provided with a central opening 3 for the admission of thesound and for the passage of the conducting pipe.
  • 5 is an inner box hav- .ing a bottom 6 the outer diameter of which is equal to the inner diameter of the box 1.
  • the bottom is equipped with a central opening for the admission of thesound, the d1ameter of'the said opening being such that when-pulling the box 5 outwardly the bottom sounds.
  • the conducting pipe 10 is drawn outwardly until its bottom end coincides with the bottom end of the innermost box.
  • the box5 is pulled outwardly by means of the ring 11, the whole contents of the resonator following this movement so that the volume of the box 1 within the space confined between the bottom 2 thereof and the bottom 6 of the box 5 acts as a resonator chamber.
  • the said lresonator chamber is gradually enlarged;
  • the resonator At its bottom the resonator is provided with a sound box made from a material which does not transmit the sound, and to the bottom of the said sound box a main conducting pipe is fixed which is adapted to be extended at will, and which may be placed on the machine to be tested.
  • the sound is transmitted through the column of air confined within the said pipe in a perfectly satisfactory way.
  • a second conducting pipe is within the resonator, and for the first testing operation it is directly connected with the main conducting pipe by inserting the pipes one into the other, so that the sound waves are conducted to the upper delivery end of the conducting pipe without being interrupted.
  • the sound waves act at the said delivery end directly on the ear of the attendant. In this case there is no resonance.
  • the conducting pipe connected with r the resonator is pulled upwardly, until its bottom end coincides with the bottom of-the inner box, so that the direct connection between the ear, and the main conducting pipe is interrupted.
  • the sound waves expand within the sound box, and they have access
  • the wall of the sound box is provided with openings permitting the said sound waves to escape.
  • the resonator consists of several telescoping boxes disposed and constructed so that the bottom of each box is the resonance board of the box surroundinggthe same.
  • the said critical point is equipped with a resonator tuned to the fre- 'quency of the expected sound of the disturb ance, the slightest disturbance will produce at the beginning within the resonator a resonance sound which will be directly audible. Therefore it is preferred continuously to equip, apparatus of any type at each critical I point with a fixed tuned resonator. To prevent such supervision resonators from being i made to sound by tones having the same frequency and coming from other parts of the system without being caused by disturbances, it is preferred to isolate the resonators in such a way that they can be affected only from the critical point.
  • acoustic apparatus for detecting vibrations of different frequency in machinery, the combination with a resonator comprising a plurality of nested chambers, means whereby said chambers may be telescoped to vary the effective volume of the chamber for altering the natural frequency of vibration 7 thereof, one of said chambers being provided with a wall portion movable therewith and extending within a second chamber to constitute a sounding board for said second chamber.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
US487085A 1929-08-20 1930-10-07 Acoustic testing apparatus for detecting irregularities of machines of any type Expired - Lifetime US1834875A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1834875X 1929-08-20

Publications (1)

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US1834875A true US1834875A (en) 1931-12-01

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Family Applications (1)

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US487085A Expired - Lifetime US1834875A (en) 1929-08-20 1930-10-07 Acoustic testing apparatus for detecting irregularities of machines of any type

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US (1) US1834875A (fr)
FR (1) FR703452A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2632521A (en) * 1953-03-24 Frequency selector
US2664274A (en) * 1951-12-22 1953-12-29 Lummus Co Method and apparatus employing sonic waves in heat exchange
US2666326A (en) * 1947-12-22 1954-01-19 Poole Volumetric measuring apparatus
US3229509A (en) * 1963-05-29 1966-01-18 Ronald A Darby Flow noise detector
DE1268781B (de) * 1964-04-16 1968-05-22 Ceskoslovenska Akademie Ved Auf verschiedene Frequenzbereiche abstimmbares Stethoskop
US4507660A (en) * 1982-07-16 1985-03-26 Advanced Electromagnetics, Inc. Anechoic chamber

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2632521A (en) * 1953-03-24 Frequency selector
US2666326A (en) * 1947-12-22 1954-01-19 Poole Volumetric measuring apparatus
US2664274A (en) * 1951-12-22 1953-12-29 Lummus Co Method and apparatus employing sonic waves in heat exchange
US3229509A (en) * 1963-05-29 1966-01-18 Ronald A Darby Flow noise detector
DE1268781B (de) * 1964-04-16 1968-05-22 Ceskoslovenska Akademie Ved Auf verschiedene Frequenzbereiche abstimmbares Stethoskop
US4507660A (en) * 1982-07-16 1985-03-26 Advanced Electromagnetics, Inc. Anechoic chamber

Also Published As

Publication number Publication date
FR703452A (fr) 1931-04-30

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