Accelerometer method and apparatus for integral display and control functions

• US 5,736,970 A
• Filed: 11/16/1994
• Issued: 04/07/1998
• Est. Priority Date: 06/19/1992
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• 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): WU, XIAO MIN
• Application Number:
  US08/342,453
• Time in Patent Office: 1,238 Days
• Field of Search: 345/33, 345/34, 345/35, 345/39, 345/42, 345/36, 345/37, 345/38, 345/44, 345/46, 345/48, 345/51, 345/52, 340/683, 340/669, 340/691, 340/753, 340/754, 73/503, 73/499, 324/162, 307/121, 361/236, 364/566, 364/508
• US Class Current: 345/35
• 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. An 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. Display apparatus responsive to a transducer for detecting mechanical vibration and outputting an analog signal in response thereto, said display apparatus comprising:

a transducer electrical output connection for receiving a transducer signal;

a display driver for generating digital signals and applying said digital signals to a plurality of output lines, said digital signals being responsive to the amplitude of said analog transducer signal;

a bar graph display connected to said plurality of output lines, said bar graph display having a plurality of optical display segments which are activatable in response to said digital signals;

an output connector having a digital trip point signal contact;

a plurality of switches for selectively interconnecting said output connector and said display driver, at least one of said switches having a first contact in common with said output connector digital trip point signal contact, said at least one of said switches having a second contract in common with a corresponding one of said plurality of output lines of said display driver, said at least one of said switches including means for selectively connecting said first and second contacts in common with each other; and

means for optically and electrically isolating said trip point control signal.

2. The apparatus of claim 1, further comprising:

each of said plurality of switches having a first contact in common with said output connector digital trip point contact, each of said plurality of switches having a second contact in common with respective ones of said plurality of display driver output lines, each of said switches including means for selectively connecting each respective first and second contact in common with each other.

3. The apparatus of claim 1, further comprising:

an integrating circuity electrically connected with said transducer output electrical connection, said integrating circuitry having an integrator output connected to said display driver.

4. The apparatus of claim 1, further comprising:

an optical isolating circuit, said optical isolating circuit being in common with said output connector digital trip point contact.

5. The apparatus of claim 1, further comprising a housing having a cavity therein defined by an internal wall:

said display driver, said bar graph display, and said plurality of switches each being disposed within said cavity; and

said housing having first and second windows, said bar graph display being disposed adjacent said first window in a position so as to be viewable through said first window and said plurality of switches being disposed adjacent second window in a position so as to be viewable through said second window.

6. The apparatus of claim 5, further comprising:

means disposed between said internal wall of said housing and said display driver for shock mounting said display driver.

7. Apparatus responsive to a transducer electrical analog output signal representative of mechanical vibration for producing a bar graph display, said apparatus comprising:

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

means for integrating said filtered electrical output signal to produce an integrating signal;

means for calibrating said integrated signal to produce a calibrated signal;

means for 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 positive correlation 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;

an output terminal;

means for applying a selected one of said digitally compatible output signals to said output terminal as an electrically isolated trip signal when said calibrated signal reaches the level of amplitude at which said selected digitally compatible output signal is generated;

a plurality of bar graph elements, each having an electrical input terminal and activatable by application of an electrical signal to its input terminal; and

means for electrically coupling each of said plurality of digitally compatible output signals to a different one of the input terminals of said bar graph elements and activating those of said bar graph elements which are coupled to the digital output signals which exceed said trip level to thereby display said digitally compatible output signals as a function of the amplitude of said calibrated signal.

8. An apparatus as set forth in claim 7 said transducer is an accelerometer.

9. Apparatus responsive to a transducer analog output signal representative of mechanical vibration for producing a bar graph display, said apparatus comprising:

means for calibrating said transducer signal and for 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 positive correlation 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;

an output terminal;

means for 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;

means for electrically and optically isolating said trip signal to preclude ground loop interference therewith;

a plurality of bar graph elements, each having an electrical input terminal and activatable by application of an electrical signal to its input terminal; and

means for electrically coupling each of said plurality of digitally compatible output signals to a different one of the input terminals of said bar graph elements and activating those bar graph elements which are coupled to the digital output signals which exceed said trip level to thereby display said digitally compatible output signals as a function of the amplitude of said calibrated signal.