Method for determining if an injector is in a blocked state

1. A method for determining if an injector ( 10 ) is blocked, said injector ( 10 ) comprising an electromagnetic solenoid ( 20 ) with a coil having a resistance (R) and an inductance (L), passed through by a power supply current of maximum intensity (I max ) and powered by a power supply voltage (E), a closure and an opening of the injector ( 10 ) being controlled by a control device (D′), said control device (D′) comprising a microcontroller ( 80 ), and a measurement resistance (r), said method comprising the following steps:

Step 1: Controlling the opening of the injector ( 10 ) by the microcontroller ( 80 ),

Step 2: Measuring by the microcontroller ( 80 ) the intensity (I) of the current passing through the measurement resistance (r) as a function of time (t),

Step 3: Determining a necessary duration (τ, τ min ) for the intensity (I) to reach a predetermined intensity value (I pred ), lower than the maximum intensity (I max ), such that:

I pred =P×I max

with P being a constant between 0 and 1,

I pred predetermined intensity value (A),

I max : maximum intensity (A),

Step 4: Computing the inductance (L) of the coil of the solenoid ( 20 ) as a function of said necessary duration (τ, τ min ),

Step 5: Comparing the value of the inductance (L) thus computed to a threshold value of the inductance (Lth),

Step 6: If the value of the inductance (L) is greater than or equal to the threshold value (Lth), then blocking the injector ( 10 ) in the closed position,

Step 7: If the value of the inductance (L) is less than the threshold value (Lth), blocking the injector ( 10 ) in the open position.

2. The method as claimed in claim 1 , wherein the method further comprises a preliminary calibration step in order to determine the threshold value of the inductance (Lth).

3. The method as claimed in claim 1 , wherein, when the constant P is between x1 and x2, with x1<x2<<1 then step 4 consists in:

Step 4: Computing of the inductance (L) of the coil of the solenoid ( 20 ) according to:

L

≅

E

(

I

pred

τ

min

)

with:

E: power supply voltage (V),

I pred : predetermined intensity (A),

τ min : necessary duration (s).

4. The method as claimed in claim 3 , wherein, when the constant P is between x3 and x4 with x4>x3>>0, then step 4 consists in:

Step 4: Computing the inductance (L) of the solenoid ( 20 ) according to:

L =τ×( R+r )

with:

L: inductance of the coil of the solenoid (H),

R: resistance of the coil of the solenoid (Ω),

r: measurement resistance (Ω),

τ: necessary duration (s).

5. The method as claimed in claim 1 , wherein said method further comprises:

before the step 1, a step of computing the value of the resistance (R) and the coil of the solenoid, such that:

R

=

E

I

max

with:

E: power supply voltage (V),

I max : maximum intensity (A),

R: resistance of the coil of the solenoid (Ω),

a preliminary calibration step in order to determine the threshold value of the inductance (Lth) as a function of the value of the resistance of the coil (R) of the solenoid.

6. A control device (D′) implementing the method as claimed in claim 5 , which comprises a microcontroller ( 80 ) comprising computation means ( 90 ) suitable for:

computing the value of the resistance (R) of the coil of the solenoid,

determining a necessary duration (τ, τ min ) to reach a predetermined intensity value (I pred ), lower than the maximum intensity (I max ),

computing the inductance (L) of the solenoid coil ( 20 ),

comparing the value of the inductance (L) thus computed to the value of the resistance (R) of the coil of the solenoid to a threshold value of the inductance (Lth) predetermined for the same value of the resistance (R) of the coil.

7. A control device (D′) implementing the method as claimed in claim 1 , which comprises a microcontroller ( 80 ) comprising computation means ( 90 ) suitable for:

determining a necessary duration (τ, τ min ) to reach a predetermined intensity value (I pred ), lower than the maximum intensity (I max ),

computing the inductance (L) of the coil of the solenoid ( 20 ),

comparing the value of the inductance (L) thus computed to a threshold value of the inductance (Lth).

8. A vehicle using the control device (D′) as claimed in claim 7 .

9. A vehicle using the control device (D′) as claimed in claim 6 .