System and method for measuring motor bearings consumption of railway vehicles

1. A system for measuring motor bearings consumption of railway vehicles, comprising:

a phonic wheel, arranged to be fixed to a shaft of a rotor, having a profile including an alternation of teeth and holes;

a sensor, arranged to measure an air-gap between the teeth of the phonic wheel and said sensor during rotation of the shaft, said sensor generating a basic sinusoidal signal function of said profile, wherein the basic sinusoidal signal is superimposed to a modulating wave, representative of a radial motion of the shaft, the basic signal and the modulating wave forming a complete signal;

wherein the sensor further comprises:

a control unit arranged to:

measure a maximum and a minimum amplitude value of the complete signal, said maximum and minimum amplitude values representing the maximum and minimum air-gap between the phonic wheel and the sensor,

determine when the shaft of the rotor has stopped rotating, and

calculate an air-gap swing value; and

memory means arranged to store said air-gap swing value;

wherein said sensor is arranged to send to an external control unit said air-gap swing value when the shaft stops rotating, said external control unit being arranged to determine the motor bearing consumption in function of said air-gap swing value.

2. The system of claim 1 , wherein the sensor is a magneto-resistive sensor.

3. The system of claim 1 , wherein the control unit is arranged to measure a frequency of the complete signal, and the memory means are further arranged to store a frequency of the complete signal related to the speed of the phonic wheel corresponding to the air-gap swing value.

4. The system of claim 3 , wherein the sensor is further arranged to send said frequency of the complete signal related to the speed of the phonic wheel.

5. A method for measuring motor bearings wearing of railway vehicles comprising the steps of:

providing a system according to claim 1 ;

generating a complete signal representative of the rotation of the phonic wheel and of a radial motion of the shaft of the rotor;

calculating, starting from said complete signal, the air-gap swing value, and storing it within the sensor;

detecting a stop of the rotation of the shaft;

transmitting to the external control unit said air gap swing value; and

determining the motor bearing consumption in function of said air-gap swing value.

6. The method according to claim 5 , further including the step of comparing the calculated air-gap swing value with respect to a value previously stored into the memory means.

7. The method according to claim 5 , wherein the step of calculating the air-gap swing value comprises the steps of:

measuring, in progressive manner, the maximum and the minimum amplitude values of the complete signal;

calculating the air-gap swing value as difference of said maximum and minimum amplitude values.

8. The method according to claim 5 , wherein the step of detecting a stop of the rotation of the shaft comprises detecting that the sensor does not measure the complete signal for a predetermined time interval.

9. The method according to claim 5 , wherein the step of transmitting to the external control unit the air-gap swing value comprises the steps of:

sending an alert signal to the external control unit to inform the external control unit that a bearing wearing-related data transmission is going to start;

converting the air-gap swing value into an air-gap swing signal;

sending the air-gap swing signal to external control unit.

10. The method according to claim 9 , wherein the alert signal is a squared signal.

11. The method according to claim 10 , wherein the frequency of the alert signal corresponds to a maximum speed of the rotor.

12. The method according to claim 9 , wherein the air-gap swing signal is a squared signal.

13. The method according to claim 12 , wherein the frequency of the air-gap swing signal corresponds to the air-gap swing value.