Accelerometer method and apparatus for integral display and control functions

• US 5,517,183 A
• Filed: 06/19/1992
• Issued: 05/14/1996
• Est. Priority Date: 06/19/1992
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Bozeman, Richard J. Jr.
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): MULLEN, THOMAS J
• Application Number:
  US07/901,626
• Time in Patent Office: 1,425 Days
• Field of Search: 340/683, 340/669, 340/691, 340/753-54, 364/566, 364/508, 73/503, 73/499, 324/162, 307/121, 361/236
• US Class Current: 340/669
• CPC Class Codes: G01H 1/00 Measuring characteristics of vibrations in solids by using direct conduction to the detector G01H9/00, G01H11/00 take precedence
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01P 15/08 with conversion into electric or magnetic values
• CPC Class Codes: G01P 7/00 Measuring speed by integrating acceleration measuring travelled distance by double integration of acceleration G01C21/16

Abstract

Method and apparatus for detecting mechanical vibrations and outputting a signal in response thereto. Art accelerometer package having integral display and control functions is suitable for mounting upon the machinery to be monitored. Display circuitry provides signals to a bar graph display which may be used to monitor machine conditions over a period of time. Control switches may be set which correspond to elements in the bar graph to provide an alert if vibration signals increase in amplitude over a selected trip point. The circuitry is shock mounted within the accelerometer housing. The method provides for outputting a broadband analog accelerometer signal, integrating this signal to produce a velocity signal, integrating and calibrating the velocity signal before application to a display driver, and selecting a trip point at which a digitally compatible output signal is generated.

Claims

1. A method for producing an error control signal from transducer electrical signals generated by a transducer and representative of mechanical vibrations of an object, said method comprising the following steps:

filtering a D.C. electrical component from said transducer electrical signals to produce a filtered electrical output signal;

integrating said filtered electrical output signal to produce an integrated signal;

calibrating said integrated signal to produce a calibrated signal;

producing from said calibrated signal a number of discrete digitally compatible electrical output signals wherein the number of said digitally compatible electrical output signals is a function of the amplitude of said calibrated signal and each said digitally compatible electrical output signal is generated at a different discrete threshold level of amplitude of said calibrated signal; and

providing an output terminal and applying a selected one of said digitally compatible output signals to said output terminal as a trip signal when said calibrated signal reaches the level of amplitude at which said selected digitally compatible output signal is generated.

2. The method of claim 1, further comprising the step of:

optically isolating said trip signal.

3. The method of claim 1 further comprising the step of:

electrically coupling said plurality of digitally compatible electrical output signals to a bar graph display for displaying said digitally compatible electrical output signals as a function of the amplitude of said calibrated signal.

4. The method of claim 3 wherein the scale of said bar graph display is linear.

5. The method of claim 3, further comprising the step of:

dampening vibrations applied to said bar graph display.

6. The method of claim 3 wherein the scale of said bar graph display is logarithmic.

7. The method of claim 1, wherein said function between the amplitude of said calibrated signal and the number of said digitally compatible output signals produced is a positive correlation.

8. Apparatus for detecting mechanical vibration and outputting an electrical control signal in response to the attainment of a specific amplitude level of said vibration, said apparatus comprising:

a housing, said housing having an opening;

an accelerometer transducer for detecting and measuring vibrations and generating an accelerometer electrical analog signal representative of such vibrations, said accelerometer transducer being mounted within said housing and provided with an output terminal for outputting said accelerometer signal;

an integrator circuit disposed and mounted within said housing and being electrically connected to said accelerometer output terminal, said integrator circuit being responsive to said analog accelerometer signal for producing a corresponding velocity signal and being provided with an integrator circuit output terminal for said velocity signal;

calibrating means coupled to said integrator circuit output terminal for calibrating said velocity signal;

an adjustable analog signal dividing circuit operatively associated with said calibrating means for producing from said calibrated velocity signal a number of discrete output signals wherein said number of discrete output signals is a function of the amplitude of said calibrated velocity signal and wherein each said discrete output signal is generated at a different discrete level of amplitude of the calibrated velocity signal, said adjustable analog signal dividing circuit being disposed within said housing;

coupling means for selectively coupling each of said discrete output signals to a connector output terminal of said apparatus, said coupling means comprising a plurality of conductors and a plurality of mechanical dip switches, each of said conductors having a different one of said dip switches operatively connected therein whereby the closing of a selected one of said dip switches conditions said apparatus to couple a selected one of said discrete output signals to the connector output terminal when the calibrated velocity signal reaches the level of amplitude at which said selected discrete output signal is generated; and

means for shock-mounting said integrator circuit, signal dividing circuit and selective coupling means within said housing, said plurality of dip switches being mounted in said housing to be accessible through said housing opening.

9. The apparatus of claim 8, further comprising:

a bar graph display, said bar graph display having a plurality of individual segments, each of which displays a different one of said number of discrete output signals.

10. The apparatus of claim 9, wherein:

said housing has a second opening and said bar graph display being disposed adjacent said second opening.

11. The apparatus of claim 9 wherein said individual segments of the bar graph display are luminous and said apparatus further comprises:

means for adjusting the brightness of said individual bar graph segments.

12. The apparatus of claim 8, further comprising:

means for electrically connecting said integrator circuit output terminal to said connector output terminal.

13. The apparatus of claim 8, wherein said adjustable analog signal dividing circuit comprises:

a display driver.

14. The apparatus of claim 8, wherein said plurality of mechanical dip switches comprises a dip switch package.

15. Apparatus for detecting mechanical vibrations of an object and producing an electrical control signal in response to the attainment of a specific amplitude level of said vibrations, said apparatus comprising:

a housing, said housing having an opening;

an accelerometer transducer for detecting said vibrations and generating an accelerometer electrical signal representative of such vibrations, said accelerometer transducer being mounted within said housing and provided with an output terminal for said accelerometer signal;

an integrator circuit for integrating said accelerometer signal, said integrator circuit being mounted within said housing and provided with an input which is electrically coupled to said accelerometer output terminal, said integrator circuit being responsive to said accelerometer signal for producing a corresponding velocity signal and being provided with an integrator circuit output terminal for said velocity signal;

a signal dividing circuit means for producing from said velocity signal a number of discrete output signals wherein the number of discrete output signals is a function of the amplitude of said velocity signal and each said discrete output signal is generated at a different discrete threshold level of amplitude of the velocity signal, said signal dividing circuit means being disposed within said housing; and

coupling means for selectively coupling each of said discrete output signals to a connector output terminal of said apparatus, said coupling means comprising a plurality of conductors and a plurality of mechanical dip switches, each of said conductors having a different one of said dip switches operatively connected therein whereby the closing of a selected one of said dip switches conditions said apparatus to couple a selected one of said discrete output signals to the connector output terminal when the velocity signal reaches the level of amplitude at which said selected discrete output signal is generated,said plurality of dip switches being mounted in said housing to be accessible for manual operation through said housing opening.

16. Apparatus as set forth in claim 15 further including means for shock-mounting said integrator circuit, said signal dividing circuit means and said coupling means within said housing.