Analysis system

摘要

A method for analyzing the condition of a machine having a rotating shaft, includes:;receiving a digital input signal (I) having a first plurality (ILENGTH) of sample values, the digital input signal (I) representing mechanical vibrations emanating from rotating the shaft so far as to cause occurrence of a vibration having a period of repetition (TR);
dividing the received digital input signal (I) into a first signal portion (2070) and a second signal portion;generating a digital output signal (O) having a second plurality (OLENGTH) of samples, the second plurality (OLENGTH) being a positive integer and lower than the first plurality (ILENGTH); the digital output signal (O) being generated in response to the first signal portion (2070) and the second signal portion.

主权项

1. An apparatus for analysing a condition of a machine having a first part which is rotationally movable at a speed of rotation in relation to a second machine part, said apparatus including:
a sensor for monitoring said movable part so as to generate at least one analogue measurement signal including at least one vibration signal component dependent on a vibration movement of said rotationally movable part; wherein said vibration signal component has a repetition frequency which depends on the speed of rotation of said first part; said measurement signal including noise as well as said vibration signal component so that said measurement signal has a first signal-to-noise ratio value in respect of said vibration signal component; an A/D-converter for generating a digital measurement data sequence in response to said measurement signal; said digital measurement data sequence having a first sample rate; a digital filter for generating a filtered measurement data signal in dependence on the digital measurement data sequence; a digital enveloper for producing an enveloped signal in response to the filtered measurement data signal; a decimator adapted to generate a decimated digital signal having a reduced sampling frequency dependent on said digitally enveloped signal; an enhancer having an input for receiving said decimated digital signal; said enhancer being adapted to produce an output signal sequence having a repetitive signal component corresponding to said at least one vibration signal component so that said output signal sequence has a second signal-to-noise ratio value in respect of said repetitive signal component; said second signal-to-noise ratio value being higher than said first signal-to-noise ratio value; and said enhancer being adapted to perform a correlation so as to produce said output signal sequence so that repetitive signal amplitude components are amplified in relation to stochastic signal components; wherein
a) said enhancer is adapted to receive a first plurality of sample values of said decimated digital signal via said input;b) said enhancer is adapted to store the received sample values in an input signal storage portion of a data memory associated with the enhancer;c) said enhancer is adapted to set a variable t to an initial value;d) said enhancer is adapted to calculate an output sample value SMDP(t) for the variable value t by employing the equation:SMDP⁡(t)=∑i=1i=CLENGTH⁢⁢I⁡(i)*I⁡(i+Sstart+t) wherein:Sstart=OLENGTH,CLENGTH =L * OLENGTH,L is an integer between 1 and 10; andOLENGTH is a desired number of output sample values, andwherein said first plurality of sample values (ILENGTH) comprises (L+2) *OLENGTH sample values;e) said enhancer is adapted to store the resulting output sample value SMDP(t) in an output signal storage portion of the data memory;f) said enhancer is adapted to check the value of variable t, wherein
f1) if, in step f), the value of t represents a number lower than the desired number of output sample values the enhancer is adapted to increase the value of the variable t, and repeat steps d) and e) and f); and whereinf2) if, in step f), the value of t represents a number equal to the desired number of output sample values said output signal sequence is delivered to said analyzer; and an evaluator for indicating a machine condition dependent on said vibration movement of said rotationally movable part in response to said output signal sequence.