Output circuit for an engine control device, and monitoring method for such a circuit

1. An engine control device ( 2 ) of a motor vehicle, the engine control device ( 2 ) comprising:

a control device ( 6 ) with means for generating a control signal and a test signal, the control signal and the test signal being provided at a first output ( 10 ) of the control device ( 6 );

at least one output circuit ( 8 ) comprising:

i) an input ( 14 ) connected to the first output ( 10 ) of the control device ( 6 ), the input ( 14 ) of the at least one output circuit ( 8 ) receiving the control signal generated by the control device ( 6 ) from the first output ( 10 ) of the control device ( 6 ), and

ii) an output ( 16 ) connected to a component ( 4 ) and equipped with switching means ( 18 ); and

a monitoring device ( 20 ) comprising:

i) a first input ( 24 ) connected to the first input ( 14 ) of the at least one output circuit ( 8 ) so that both the input ( 14 ) of the at least one output circuit ( 8 ) and the first input ( 24 ) of the monitoring device ( 20 ) directly receive from the first output ( 10 ) of the control device ( 6 ), as a same direct input signal, the control signal when generated by the control device ( 6 ) and the test signal when generated by the control device ( 6 ),

ii) a second input ( 22 ) connected to the output ( 16 ) of the output circuit ( 8 ), the second input ( 22 ) receiving the output ( 16 ) of the at least one output circuit ( 8 ) for monitoring the output signal at the output ( 16 ) of the at least one output circuit ( 8 ), and

iii) a connection control means associated with time delay means for interrupting a connection between the output ( 16 ) of the at least one output circuit ( 8 ) and the component ( 4 ), wherein a time delay is started upon detection of the output signal from the output ( 16 ) of the at least one output circuit ( 8 ) to the first input ( 24 ) of the monitoring device ( 20 ), said time delay defining a time interval of predetermined length, and wherein when during said time interval no test signal is received, the connection control means actuates the switching means ( 18 ) to open the connection between the output ( 16 ) of the at least one output circuit ( 8 ) and the component ( 4 ).

2. The control device as claimed in claim 1 , wherein the monitoring device ( 20 ) is physically integrated into the output circuit ( 8 ).

3. The control device as claimed in claim 1 , wherein the monitoring device ( 20 ) is a separate circuit from the output circuit ( 8 ).

4. The control device as claimed in claim 1 , wherein the monitoring device ( 20 ) comprises analysis means in order to determine whether the signal received at the first input ( 24 ) thereof corresponds to a predetermined type of signal.

5. The control device as claimed in claim 1 , further comprising analysis means in order to determine whether the signal received at the second input ( 22 ) thereof corresponds to a predetermined type of signal.

6. A method of monitoring an output circuit ( 8 ), said output circuit ( 8 ) comprising:

an input ( 14 ) that receives signals, each signal being a control signal generated by a control device ( 6 ) or a test signal, and

an output ( 16 ) connected to a component ( 4 ) and equipped with switching means ( 18 ),

the method comprising using a monitoring device ( 20 ) comprising i) a first input ( 24 ) connected to the input ( 14 ) of said output circuit ( 8 ) so that both the input ( 14 ) of said output circuit ( 8 ) and the first input ( 24 ) of the monitoring device ( 20 ) directly receive from the control device ( 6 ), as a same direct input signal, the control signal when generated by the control device ( 6 ) and the test signal, ii) a second input ( 22 ) connected to the output ( 16 ) of said output circuit ( 8 ), and iii) a connection control means associated with time delay means for interrupting a connection between the output ( 16 ) of said output circuit ( 8 ) and the component ( 4 ),

the method further comprising the following steps:

a) monitoring the output signal at the output ( 16 ) of the output circuit ( 8 ) as well as the test signal received at said input ( 14 ) of said output circuit ( 8 ),

b) initiation of a time delay on detection of the output signal at the output ( 16 ) of the output circuit ( 8 ) to the first input ( 24 ) of the monitoring device ( 20 ), said time delay defining a time interval of predetermined length, and

c) when during said time interval with no test signal being received, the connection control means initiating action on the switching means ( 18 ) to open the connection between the output circuit ( 8 ) and the component ( 4 ), and return to step a), and

d) when during said time interval a test signal is received, return to step b).

7. The method of monitoring as claimed in claim 6 , wherein each signal received at the input of the monitoring device is analyzed, and upon the analysis determining that the received signal does not correspond to a predetermined type of signal, the received signal is regarded as not being received.

8. The control device as claimed in claim 2 , wherein the monitoring device ( 20 ) comprises analysis means in order to determine whether the signal received at the first input ( 24 ) thereof corresponds to a predetermined type of signal.

9. The control device as claimed in claim 3 , wherein the monitoring device ( 20 ) comprises analysis means in order to determine whether the signal received at the first input ( 24 ) thereof corresponds to a predetermined type of signal.

10. The control device as claimed in claim 2 , further comprising analysis means in order to determine whether the signal received at the second input ( 22 ) thereof corresponds to a predetermined type of signal.

11. The control device as claimed in claim 3 , further comprising analysis means in order to determine whether the signal received at the second input ( 22 ) thereof corresponds to a predetermined type of signal.

12. The control device as claimed in claim 4 , further comprising analysis means in order to determine whether the signal received at the second input ( 22 ) thereof corresponds to a predetermined type of signal.