Data processing: measuring – calibrating – or testing – Measurement system – Performance or efficiency evaluation
Reexamination Certificate
1999-06-21
2002-01-08
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Performance or efficiency evaluation
C702S187000, C702S033000, C702S034000, C324S545000, C318S434000, C318S700000, C318S798000
Reexamination Certificate
active
06338029
ABSTRACT:
INCORPORATION BY REFERENCE OF OTHER U.S. PATENTS
The applicant hereby incorporates by reference the disclosures of Robert P. Siegel et al., “Predictive fuser misstrip avoidance system and method,” U.S. Pat. No. 5,406,363, and Robert P. Siegel et al., “Predictive decurler apparatus and method,” U.S. Pat. No. 5,414,503, verbatim and with the same effect as though such disclosures were fully and completely set forth herein.
FIELD OF THE DISCLOSURE
This disclosure relates generally to electric motors and, in particular, to a method for determining when an electric motor is acceptable.
BACKGROUND OF THE INVENTION
Electric motors are commonly used in many devices and machines. For example, a copying machine uses a plurality of motors for various applications. One such application is for driving feed rollers for conveying a sheet of paper through a copying machine paper path for processing by the various copying functions.
Typically machines are returned to their manufacturer for service. When this occurs, it is common to remove the various motors from the machine. After removal, each motor is analyzed to determine if it is in acceptable condition to be re-used. The problem, therefore, is how to test an electric motor and determine its acceptability in an efficient manner.
Present methods of motor testing generally involve a “one parameter at a time” approach. Each parameter is measured and a determination is made to accept or reject the motor with respect to each parameter independently. For example, numerous motor testing methods are based on vibration analysis and current signature analysis. These methods are adequate when distinct defects are present, for example when looking for defects in a new production environment or in a field service troubleshooting situation where a problem has been reported. These methods are effective in detecting “hard failures” where the motor in question has departed in a clear and dramatic way from a known acceptable state.
The existing methods, however, do not address the case of a “soft is failure” where a motor is still performing its intended function, but has experienced a more subtle degree of degradation.
Therefore, there is a need for an improved method for determining when an electric motor is acceptable.
SUMMARY OF THE INVENTION
In one aspect of the invention, a testing apparatus is arranged for coupling to a motor. The testing apparatus determines when the motor is acceptable in accordance with a method. The method comprises: a) measuring a time required for the motor to reach a running speed in a steady state, thus forming a time-to-speed parameter; b) measuring a difference between an instantaneous speed and an average speed in the steady state, thus forming a speed variation parameter; c) measuring a maximum value of the motor current, thus forming a maximum current parameter; d) measuring a motor current in the steady state, thus forming a running current parameter; e) measuring a motor vibration energy in the steady state, thus forming a vibration energy parameter; and f) determining when the motor is acceptable based on the time-to-speed parameter, the speed variation parameter, the maximum current parameter, the running current parameter and the vibration energy parameter.
In another aspect of the invention, a testing apparatus is arranged for coupling to a motor. The testing apparatus determines when the motor is acceptable in accordance with a method. The method comprises: a) measuring a time required for the motor to reach a running speed in a steady state, thus forming a time-to-speed parameter; b) measuring a difference between an instantaneous speed and an average speed in the steady state, thus forming a speed variation parameter; c) measuring a maximum value of the motor current, thus forming a maximum current parameter; d) measuring a motor current in the steady state, thus forming a running current parameter; e) measuring a motor vibration energy in the steady state, thus forming a vibration energy parameter; f) measuring a motor current energy in the steady state, thus forming a current energy parameter; and g) determining when the motor is acceptable based on the time-to-speed parameter, the speed variation parameter, the maximum current parameter, the running current parameter, the vibration energy parameter and the current energy parameter.
REFERENCES:
patent: 4839830 (1989-06-01), Amey et al.
patent: 5629870 (1997-05-01), Farag et al.
patent: 5680025 (1997-10-01), Bowers, III et al.
patent: 5729911 (1998-03-01), Canada et al.
Abbata Salvatore A.
Siegel Robert P.
Egan Wayne J.
Hoff Marc S.
Vo Hien
Xerox Corporation
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