Method for diagnosing an earth fault of a start/stop unit of a motor vehicle
View Patent ↗A method for diagnosing a ground fault of a start/stop unit of a motor vehicle and a start/stop system implementing the method. The method comprises, in a preliminary phase, providing a driver device with a ground that can be switched between two positions and connecting a ground output of a start/stop device to the switchable ground. When the vehicle is in operation, at the time of a start/stop instruction: reading a first value of the signal at the input of the reading circuit, then temporarily switching the switchable ground from a first position connected to a ground of the vehicle to a second position connected to a ground resistor; reading a second value of the signal received by the reading circuit when the ground is switched to the ground resistor, and comparing the two read values in order to diagnose a short-circuit to ground fault of the start/stop unit.
1. A method of diagnosing a ground fault of a start/stop unit ( 4 ) adapted to control the starting and the stopping of a vehicle motor, said unit being part of a start/stop device ( 10 ) further including a ground output ( 3 ), said device ( 10 ) being further associated with a driver device ( 11 ) including a circuit ( 15 ) for reading the status of the start/stop unit, said diagnostic method comprising:
in a preliminary phase:
equipping the driver device ( 11 ) with a ground ( 20 ) switchable between two positions and connecting the ground output ( 3 ) of the start/stop device ( 10 ) to said switchable ground ( 20 ),
during operation of the vehicle, at the time of a start/stop instruction:
reading (step 210 ) a first value of the signal present at the input of the reading circuit ( 15 ), then,
temporarily switching (step 220 ) the switchable ground ( 20 ) from a first position connected to a ground ( 16 ) of the vehicle to a second position connected to a ground resistor (R M ),
reading (step 230 ) a second value of the signal received by the reading circuit ( 15 ) during the switching of the ground to the resistor (R M ), and
comparing the first and second values (step 240 ), and
if the first and second values read are significantly different, diagnosing an absence of a short-circuit to ground,
if the first and second values read are substantially equal, diagnosing (step 260 ) a short-circuit to ground fault of the start/stop unit ( 4 ).
2. The diagnostic method as claimed in claim 1 wherein the first and second values read are voltage values.
3. A system ( 100 ) for starting/stopping a vehicle motor, including:
a start/stop device ( 10 ) including a unit ( 4 ) for starting/stopping the motor of the vehicle and a ground output ( 3 ), and
a driver circuit ( 11 ) including:
a circuit ( 15 ) for reading the status of the start/stop unit ( 4 ), wherein
the driver device ( 11 ) further includes:
a switchable ground ( 20 ) including a ground switch ( 21 ) connected on the one hand to the ground output ( 3 ) of the start/stop device ( 10 ) and on the other hand to a ground ( 16 ) of the vehicle, said ground switch ( 21 ) being adapted to switch between a position connected to the ground ( 16 ) of the vehicle and a position connected to a ground resistor (R M ).
4. The start/stop system ( 100 ) as claimed in claim 3 , wherein the ground switch ( 21 ) is connected in parallel with the ground resistor (R M ).
5. The start/stop system ( 100 ) as claimed in claim 4 , wherein the ground switch ( 21 ) is driven by a computer ( 12 ) of the driver device ( 11 ).
6. The start/stop system ( 100 ) as claimed in claim 4 , wherein the ground switch ( 21 ) is a protected electronic transistor.
7. The start/stop system ( 100 ) as claimed in claim 3 , wherein a voltage divider bridge is created by the ground resistor R M and a reading resistor R L of the reading circuit ( 15 ).
8. The start/stop system ( 100 ) as claimed in claim 5 , wherein the ground switch ( 21 ) is a protected electronic transistor.
9. The start/stop system ( 100 ) as claimed in claim 4 , wherein a voltage divider bridge is created by the ground resistor R M and a reading resistor R L of the reading circuit ( 15 ).
10. The start/stop system ( 100 ) as claimed in claim 5 , wherein a voltage divider bridge is created by the ground resistor R M and a reading resistor R L of the reading circuit ( 15 ).
11. The start/stop system ( 100 ) as claimed in claim 6 , wherein a voltage divider bridge is created by the ground resistor R M and a reading resistor R L of the reading circuit ( 15 ).
12. The start/stop system ( 100 ) as claimed in claim 8 , wherein a voltage divider bridge is created by the ground resistor R M and a reading resistor R L of the reading circuit ( 15 ).