Noise quality detector for electric motors or other machines

• US 3,913,084 A
• Filed: 03/26/1973
• Issued: 10/14/1975
• Est. Priority Date: 03/26/1973
• Status: Expired due to Term

• Current Assignee: John G. Bollinger, Robert J. Sandberg
• Original Assignee: John G. Bollinger, Robert J. Sandberg
• Inventors: Sandberg, Robert J., Bollinger, John G.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Beauchamp, John P.
• Application Number:
  US05/345,186
• Time in Patent Office: 932 Days
• Field of Search: 73/67,67.2,71.2,71.4 340/261,248A
• US Class Current: 340/683
• CPC Class Codes: G01H 3/12 by electric means G01H3/14 takes precedence
• CPC Class Codes: G01R 31/343 in operation

Abstract

Such detector is adapted to detect a transducer signal indicative of the level of noise, or the actual measured noise, produced by an electric motor or the like, particularly for the purpose of quality control in connection with a production line, automated or manual, so that motors which produce excessive noise or are defective may be identified and rejected. The detector employs an accelerometer or some other transducer, i.e. a microphone, for receiving the vibration or noise from each motor and converting the noise into electrical signals. After amplification, the signals are sent through a bandpass filter or a plurality of filters which selectively transmit those signals which are within a particular band of frequencies, while attenuating signals which are outside such band. The filter preferably has controls for adjusting both the upper and lower cutoff frequencies of the filter. The output signals from the filter are compared with a predetermined level. One or more indicating devices are operated by the comparison device to indicate whether the detected noise level is above or below such level. The indicating devices may be in the form of lamps or a meter. It is preferred to detect both the peak signal level and the average signal level so that the motor will be rejected if either level is above the desired level. The disclosed device is adapted to detect and indicate the noise quality of a plurality of motors in sequence on an automatic basis.

Claims

1. A device for detecting, measuring and characterizing the vibration or noise produced by a machine or other unit, comprising a transducer for receiving the vibration or noise from such unit and converting the vibration or noise into electrical signals, at least one band-pass filter for receiving and selectively transmitting the electrical signals from said transducer within a selected band of frequencies, an indicating device for indicating excessive vibration or noise, a peak detector for receiving the output signals from said filter and developing a peak detector output corresponding to the peak value of said output signals, comparison means for actuating said indicating device if the input to said comparison means exceeds a predetermined level, a first diode for supplying said peak detector output to the input of said comparison means, an averaging detector for receiving the output signals from said filter and developing an averaging detector output corresponding to the average value of said output signals, and a second diode for supplying the averaging detector output to the input of said comparison means, whereby said comparison means is responsive only to the larger of said peak detector output and said averaging detector output, the larger of said outputs being effective to back bias the diode which would otherwise supply the smaller of said outputs.

2. A device according to claim 1, including adjusting means for adjusting the level of at least one of said detector outputs in relation to the predetermined level established by said comparison means.

3. A device according to claim 1, in which said comparison means includes means for adjusting the predetermined level established by said comparison means.

4. A device according to claim 1, in which said comparison means includes means for adjusting the predetermined level established by said comparison means, said device including means for adjusting theh level of at least one of said detector outputs in relation to the predetermined level established by said comparison means.