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1. (WO2019043572) DIAGNOSTIC DEVICE AND METHOD FOR SOLENOID VALVES
Nota: Texto obtenido mediante procedimiento automático de reconocimiento óptico de caracteres.
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Claims

1. A diagnostic method for diagnosing a malfunction in a solenoid valve, wherein the solenoid valve comprises an electromagnet (10) and a valve body (12) wherein one or more orifices (14, 16, 18) are provided for the passage of a pressurized fluid, and wherein the electromagnet (10) comprises a solenoid (102) which is drivable by a solenoid current and a magnetic circuit comprising a movable core (104) situated and slldable in the solenoid, the method comprising the steps of:

a) storing in a non-volatile memory register the reference features of the waveform of the solenoid current,

b) detecting the features of the waveform of the solenoid current during the operation of the solenoid valve;

c) comparing the reference features with the detected features;

d) in the event of a deviation between the value of the detected features and the value of the reference features, generating an alarm signal for malfunction of the solenoid valve.

2. A method according to claim 1, wherein step d) comprises, before the generation of the alarm signal:

- a step d1) of comparing the value of the pressure of the fluid entering in the inlet orifice of the solenoid valve with a predetermined pressure value range;

- in the event of deviation of the pressure value with respect to said range of predetermined pressure values, a step d2) of adjusting the pressure value and repeating steps b) and c) ;

the alarm being generated in the event of a deviation between the value of the features detected and the value of the reference and fluid pressure features within the range of predetermined pressure values.

3. A method according to claim 1 or 2, wherein the features of the waveform of the solenoid current that are stored and compared are the slope of a first waveform section between the instant of excitation of the solenoid valve and the first current peak (IPEAK) generated by the engagement of the mobile core and the slope of the second waveform section between the current peak (IPEAK) and the next minimum point (IVALLEY) of the value of the solenoid current .

4. A method according to the preceding claim, further comprising the steps of:

- checking whether the waveform of the solenoid current has, after said first current peak (IPEAK) and before reaching the minimum current point (IVALLEY) , a deflection and/or or further minimum (m) and maximum (M) relative points;

calculating the average values of the current derivative over time in an immediately preceding time interval and in a time interval immediately following the inflection point or relative minimum point;

- comparing said average values with corresponding reference values;

- checking whether at least one of said average values is, in absolute value, lower than the corresponding reference value.

5. A method according to the preceding claim, wherein the presence of said inflection and/or of said additional maximum (M) and minimum (m) relative points is detected by calculating the derivative of the current over time (di/dt) and verifying whether said derivative assumes a null or positive value in two instants of time (Ta, Tb) in a time interval following the instant in which the waveform peak occurred and before the solenoid current reaches the steady state value.

6. A method according to any one of the preceding claims, wherein the features of the solenoid current waveform comprise at least the first time interval (T1) that elapses between the instant of excitation of the solenoid and the instant of the current peak generated by the engagement of the movable core.

7. A method according to the preceding claim, wherein said first time interval is obtained by means of an analog peak detection circuit (40) which compares the value of the instant solenoid current with the value of the solenoid current to which a predetermined delay is applied, or by means of a digital sampling circuit of the solenoid current waveform.

8. A method according to any one of the preceding claims, wherein the reference features are features of the solenoid current waveform acquired when the solenoid valve is in a test phase during or after release from the factory.

9. A method according to any one of claims 1-7, wherein the reference features are features of the waveform of the solenoid current obtained from average values relative to a set of values previously acquired.

10. A diagnostic device for diagnosing a malfunction in a solenoid valve, wherein the solenoid valve comprises an electromagnet (10) and a valve body (12) wherein one or more orifices (14, 16, 18) are provided for the passage of a pressurized fluid, and wherein the electromagnet (10) comprises a solenoid (102) which is drivable by a solenoid current and a magnetic circuit comprising a movable core (104) situated and slldable in the solenoid, the diagnostic device comprising an electronic diagnostic circuit with microcontroller configured to implement the diagnostic method according to any one of the preceding claims.

11. A device according to the preceding claim, wherein the diagnostic circuit is implemented on a power supply and control circuit board suitable to be mounted on the solenoid valve.

12. A device according to claim 10 or 11, comprising communication means suitable to implement communication between the microcontroller of the electronic diagnostic circuit and an external control unit.

13. A device according to the preceding claim, wherein said communication means are suitable to transmit a status signal to the external control unit, which may assume at least two logical levels representative of the operational state of the solenoid valve.

14. A device according to any one of claims 10 to 13, wherein the electronic diagnostic circuit comprises a current sampling circuit suitable to sample the waveform at predetermined time intervals.

15. A device according to any one of claims 10 to 14, wherein the electronic diagnostic circuit comprises an analog peak detection circuit (40) comprising an operational amplifier (42) with comparator function the inverting input terminal of which receives the solenoid current detected through a shunt resistor (RSHUNT) and the non-inverting input terminal of which receives the solenoid current to which is applied a delay given by an RC network.

16. A solenoid valve comprising an electromagnet (10) and a valve body (12) wherein one or more orifices (14,

16. 18) are provided for the passage of a pressurized fluid and wherein the electromagnet (10) comprises a solenoid (102) which is drivable by a solenoid current and a magnetic circuit comprising a movable core (104) situated and slidable in the solenoid, the solenoid valve further comprising a diagnostic device according to any one of claims 10 to 15.

17. A solenoid valve according to the preceding claim, comprising a power supply and control circuit board (120), the diagnostic device being implemented on said power supply and control circuit board (120) .

18. A solenoid valve according to the preceding claim, wherein the power supply and control circuit board is provided with an electrical connector having a pair of power supply terminals and an electrical diagnostic terminal connectable to an external control unit.

19. A solenoid valve island, comprising a power supply and control circuit board for all the solenoid valves of the valve island, said power supply and control circuit board comprising an electronic diagnostic circuit with microcontroller adapted to Implement a diagnostic method according to any one of claims 1-9, wherein the reference features are related to each of the solenoid valves of the valve island or groups of solenoid valves of the solenoid valve island, and wherein the detected features are obtained by exciting separately each solenoid valve or each group of solenoid valves.