EP0312560A1

EP0312560A1 - Device and process for checking the wiring of an ignition power module.

Info

Publication number: EP0312560A1
Application number: EP88903270A
Authority: EP
Inventors: Christian Rousseau; Gerard Saint-Leger
Original assignee: Renault SAS; Regie Nationale des Usines Renault
Current assignee: Renault SAS; Regie Nationale des Usines Renault
Priority date: 1987-04-03
Filing date: 1988-04-01
Publication date: 1989-04-26
Anticipated expiration: 2008-04-01
Also published as: FR2613494A1; FR2613494B1; WO1988007630A1; US4932381A; DE3877890D1; DE3877890T2; EP0312560B1

Abstract

L'invention concerne un dispositif de vérification du câblage du module de puissance d'allumage (2) d'un système électronique d'allumage-injection pour un moteur à combustion interne. Il comporte une ligne (9) dite de test connectée entre le module (2) et le calculateur électronique (1) d'allumage-injection. Grâce à ce dispositif est établi un procédé de vérification du câblage devant détecter successivement la présence d'un circuit ouvert ou d'un court-circuit entre le module de puissance d'allumage (2) et son circuit de commande (8).The invention relates to a device for checking the wiring of the ignition power module (2) of an electronic ignition-injection system for an internal combustion engine. It comprises a so-called test line (9) connected between the module (2) and the ignition-injection electronic computer (1). With this device, a method of verifying the wiring is established, which must successively detect the presence of an open circuit or a short circuit between the ignition power module (2) and its control circuit (8).

Description

DEVICE AND METHOD FOR CHECKING THE WIRING OF THE IGNITION POWER MODULE

1

The invention relates to a device and a method for checking the wiring of the ignition power module in an electronic ignition system and in an electronic ignition-injection system for an internal combustion engine.

In an electronic ignition-injection system for an internal combustion engine, the electronic ignition part which fulfills the same function as an electronic ignition system is an equipment delivering, at the appropriate time, a high voltage spark to the spark plug. of the cylinder considered. This equipment comprises an ignition power module carrying the coil, a description of which will be made later illustrated by FIG. 1.

Failure to connect this module which is not diagnosed could lead to replacement of a correct module.

To avoid these unnecessary replacements, the invention provides a method of verifying the wiring of the ignition power module, intended to detect open circuits or short circuits to ground on the control wire of the module.

For this, the object of the invention is first of all a device for checking the wiring of the ignition power module of an electronic ignition-imection system in an internal combustion engine, system comprising inter alia a flywheel with teeth on its periphery scrolling past a magnetic sensor connected to an electronic computer calculating the ignition advance and fuel ignition time, and sending a signal, significant of the advance to l ignition, to the ignition power module control circuit, characterized in that it comprises a so-called test line connecting the electrical connection, which exists between the module and its control circuit, to a test input of the computer electronic.

According to another characteristic of the invention, it also relates to a method for verifying the wiring of the ignition power module. an electronic ignition-injection system intended to detect first an open circuit between the module and its control circuit, then a short circuit between the module and the ground.

Other characteristics and advantages of the invention will appear during the description which follows, illustrated by the following figures which represent:

- Figure 1: an electronic ignition-iniection system comprising the device according to the invention;

- Figure 2: the signals S _D , S _P and S _ALL respectively representing the electrical image of the toothed target, the top dead centers and the spark ignition control;

- Figures 3, 4 and 5: the different stages of the verification process according to one embodiment of the invention.

As shown in FIG. 1, an electronic ignition-injection system notably comprises a fuel supply circuit with injectors, not shown, an electronic computer 1 ensuring the calculation of the ignition advance and the time injection, means for acquiring the parameters influencing the calculation of the air-fuel dosage, and an ignition power module 2 carrying the coil.

The ignition power module 2 includes a coil with low primary impedance for passing high currents for a very short time, an ignition-specific analog circuit which regulates the current in the coil primary and a switching circuit consisting of a Darlington transistor.

One of the means for acquiring influence parameters is a flywheel 3 comprising a target consisting of teeth D _i arranged at its periphery. This flywheel is placed on the motor shaft in the vicinity of the starter ring. In a particular exemplary embodiment, this target comprises 44 teeth D _i uniformly distributed including two times two teeth are missing to achieve an absolute reference 5 placed 90 ° before the top and bottom dead centers. A magnetic position sensor 6, in front of which the teeth D _i of the target pass by, delivers a signal S _C which is then shaped by a specific circuit 7 to supply the microprocessor of the computer 1 with an electric image S _D of the target, each pulse I _D of the signal S _D corresponding to a tooth D _i , as well as a signal S _P representative of the top dead centers, the falling edge of each pulse I _P corresponding to a top dead center. These signals S _D and S _P are shown in FIG. 2. This specific circuit 7 may or may not be integrated into the computer 1.

From this signal S _D , the computer 1 determines the engine speed N and the phase to the nearest degree with respect to the TDC. It then defines the degree of ignition advance as a function of the speed N, the pressure in the manifold and other parameters such as the air temperature at the intake l'ad _air , or the water temperature θ _water . This degree of advance A _V at ignition gives the position of the ignition front of the coil. The specific circuit 7 calculates the conduction time of the coil from the engine speed N and the voltage U _bat delivered by the battery and sends an electrical signal S _ALL to the control circuit 8 of the ignition power module 2, representing (FIG. 2) a series of pulses I _A whose duration d is significant of the conduction time of the coil and whose falling edge corresponds to the discharge of the coil therefore to the ignition of the corresponding spark plug. The time interval t _a between the falling edge of the pulse I _A corresponding to the ignition instant and the falling edge of the pulse l _P corresponding to the top dead center is significant of the advance A _V to ignition. This circuit 8 is constituted by a transistor T controlled to be conducting. When the transistor T of circuit 8 is on, the signal arriving at the ignition power module is processed by its analog circuit so as to control the power transistor authorizing the circulation of a large current in the primary of the coil.

The invention aims to check the wiring of the ignition power module

2. For this, a so-called test line 9 is created connecting the electrical connection 10 which exists between the module 2 and its control circuit to a test input E _T of the electronic computer 1 with a resistor R of high value placed at the end of this test line so that the information on test line 9 is at high level 1 when the power module 2 is disconnected.

The method of verifying the wiring of the ignition power module consists on the one hand of detecting an open circuit occurring when the module 2 is disconnected from its control circuit 8 and on the other hand of verifying that there is has no short circuit.

The process for verifying the presence of an open circuit takes place both in starter sequence and at any time during engine operation.

This verification comprises different stages, the succession of which is shown in FIG. 3. The hierarchical program carried out by the ignition-injection computer 1 comprises a main part for carrying out priority tasks such as the calculation of the ignition advance. , the injector opening time or the idling speed.

This program is carried out at each so-called IT-PMH interruption, sent by the specific circuit 7 to the microprocessor of the computer 1 on the falling edges of the pulses I _P of the signal S _P corresponding to the top dead center (TDC). This program further comprises a step a) of reading the signal S _T appearing on the test input E _T of the microprocessor, followed by a step b) of comparing the value of this signal S _T with the low level O.

Since only an ignition advance is made and not a delay, at any operating point after a top dead center, the signal S _T must be at low level O if there is no error of wiring.

If the module 2 is disconnected, the test line 9 is connected to the voltage V _N , equal to 5 volts, via the resistor R and the signal S _T is at the high level 1.

In step c), the fault state is signaled and a fault indicator can be lit. Thus to check the wiring of the ignition power module 2, the computer 1 reads the test bit of the signal S _T fairly quickly after a top dead center. Then the main program of calculator continues.

In the case where it has been checked in starter sequence that the module is not in open circuit, it must then be checked that there is no short-circuit, that is to say that module 2 does not is not grounded. To avoid problems due to the offset between the ignition advance value calculated by the microprocessor and the advance value actually applied at a given time, this check will only be carried out in starter sequence, i.e. - say when the starter is energized and the engine speed N is below a threshold. The invention proposes to verify that the level of the signal S _T of the test line 9 passes well to the high level 1 between the instant t ₁ where the coil is driven and the ignition instant t ₂ . Given the possible variations in the conduction time d of the coil which is unknown for the electronic computer 1, it is necessary to make the test as close as possible to the ignition time t ₂ which is known since it is calculated by the microprocessor based on the synchronization of the top dead centers and the ignition advance parameters.

The procedure for checking whether or not there is a short circuit in the connection of the ignition power module is carried out as follows.

At the start of the main program executed by the electronic computer 1, it is first checked that the engine is indeed under starter sequence. If this first condition is not met, the short circuit test will not be done. On the other hand, this condition being fulfilled, a second condition is necessary: the number of top dead centers n _TDC identified since the ignition of the engine must be equal to or greater than a threshold x (x = 5 for example). In fact, if this number _TDC is less than the determined threshold, the microprocessor of the electronic computer 1 has not yet had time to calculate a value of advance on ignition and that which is then delivered to the power module d ignition 2 is that programmed in the specific circuit 7.

These two conditions - starter sequence and n _TDC equal to or greater than a threshold - then being satisfied, the tooth D _i of the flywheel 3 is determined on which the test will be carried out. According to an original characteristic of the invention, this tooth is obtained by taking the whole part of the fraction:

with:

A _V the degree of ignition advance;

d _i the number of motor degrees corresponding to the duration of a tooth D _i of the target;

and d ₂₀ the number of the 20th tooth corresponding to a top dead center.

In a four-cylinder engine, the duration of a tooth is 8º, the ignition advance under starter is for example 8 ° and a top dead center occurs on the twentieth tooth so that the tooth on which will be carried out the verification of the short circuit is tooth 19.

Once the tooth D _i on which the short-circuit test must be executed is determined, the main program of the computer 1 continues, then comprising authorization to be interrupted by the signal S _D corresponding to the teeth D _i of the target 3.

When an IT - SD interrupt by the signal S _D arrives, the computer 1 will interrupt its main program and execute an interrupt program during which it must first read the number of the tooth D _i identified by the sensor 6 then compare it with the determined number of the test tooth and in the event of coincidence, it will read the level of the signal S _T leading to the input E _T of the microprocessor. If the signal is at low level 0, unlike the ignition S _ALL control signal which is at 1, this proves that the ignition power module 2 is connected to earth and the fault state must be reported . Figures 4 and 5 show the steps of the process for verifying a short circuit, according to a particular non-limiting embodiment.

In the main program of the electronic computer 1, at the start of a TDC interruption, it is checked in step d) if the starter sequence is finished, in which case the short circuit cannot be checked and therefore it is not authorized not, in step e), the IT-SD interruptions of the main program of the computer 1, caused by the pulses I _D of the signal SD at each passage of a tooth D _{i in} front of the sensor 6.

On the other hand, if the engine is still under starter, the main program carries out step f) during which firstly the counter of the teeth D _i , existing in the computer 1, is reset to 0, secondly the interruptions IT-SD of the program by the signal teeth S _D are authorized and finally we give the value 1 to a partial processing indicator, called Flag IT-SD processing, positioned in the computer memory. Then the main program continues.

If an IT-SD interruption caused by the teeth signal S _D occurs, for example in step g), the computer performs the interruption program represented in FIG. 5, and comprising step h) of incrementing the counter teeth then step i) of reading the value of the flag for partial processing Flag IT-SD processing.

At this instant of the main program, the value of the indicator is 1 and the short circuit is not checked.

If there are no IT-SD interruptions, the computer program performs step k) consisting of comparing the number of high dead centers nPMH identified since the engine was contacted with a determined threshold x. If this number _TDC is less than x (x = 5 for example), we know that the microprocessor has not yet had time to calculate a value in advance to ignition and that which is delivered to the ignition power module 2 is that programmed in the specific circuit 7. In this case, it is decided not to make the short circuit test and the step 1) consists on the one hand of incrementing the counter of the top dead centers existing in the computer 1 and on the other hand of giving a non-existent value to the test tooth so as not to make this test.

If the number of top dead centers n _TDC is equal to or greater than the threshold x, in step m) the tooth D _i of the flywheel 3 on which the test will be carried out is determined, according to the formula previously stated.

Once this step m) has been carried out, the main program of the computer continues until step n) for resetting the partial processing indicator allowing the verification of the short circuit when an IT-SD interruption by the signal S _It will happen.

In such an IT-SD interruption case, the computer will execute the IT-SD interruption program of FIG. 5 on which it is directed in step g). In step i), the flag flag IT-SD processing is at 0 so that the program continues with step p) of reading the tooth D _i identified by the sensor 6. If this tooth D _i n is not the tooth on which the test must be done, said test is not done and we wait for a new interruption of the signal teeth S _D to do it.

If, on the other hand, the test tooth is identified, in step q) the level of the signal S _T is read, leading to the input E _T of the microprocessor: if the signal is at low level O, unlike the control signal S _ALL ignition which is at 1, this proves that the ignition power module 2 is connected to earth and in step r) the fault state is signaled with lighting of a fault indicator if necessary.

Thanks to the invention, open circuits and short circuits to ground on the control wire of the ignition power module can be detected, avoiding unnecessary replacement of the module.

Claims

R E V E N D I C A T I O N S

1 / Device for checking the wiring of the ignition power module of an electronic ignition-injection system in an internal combustion engine, system comprising inter alia a flywheel (3) provided with teeth (D _i ) at its periphery running past a magnetic sensor (6) connected to an electronic computer (1) calculating the advance (A _V ) at ignition and the fuel injection time, and sending a signal (S _ALL ), significant of the ignition advance, to the control circuit (8) of the ignition power module (2), characterized in that it comprises a so-called test line (9) connecting the electrical connection (10) , which exists between the module (2) and its control circuit (8), at a test input (Ey) of the electronic computer (1).

2 / Method for verifying the wiring of the ignition power module (2) of an electronic ignition-injection system, in an internal combustion engine, comprising a verification device according to claim 1, characterized in that it consists in detecting an open circuit between the module (2) and its control circuit (8), said detection being carried out by the computer (1) which, each time its program is interrupted by a top dead center, also performs the following steps :

- a) reading of the signal (S _T ) appearing on the test line (9) upon detection of a top dead center in the signal (S _P );

- b) comparison of the value of the signal (S _T ) with the low level O;

- c) If S _T = 1, reporting of the fault state. 3 / A verification method according to claim 1, characterized in that it consists in detecting, in the absence of open circuit and in starter sequence only, a short circuit between the ignition power module (2) and the mass by carrying out the following steps during the main program of the computer (1),

- checking the operation of the engine in starter sequence; if yes :

- comparison of the number (n _TDC ) of top dead centers appeared after the ignition of the starter, with a determined threshold (x); if nPMH ≥ x:

determination of the tooth (D _i ) of the flywheel (3) at which the test will be made;

- identification of the test tooth;

- reading of the signal (S _T ) leading to the test input (E _T ) of the microprocessor of the computer (1);

- reporting of a fault condition of the ignition power module (2) by short circuit.

4 / verification method according to claim 3, characterized in that the determination of the tooth (D _i ) of the flywheel (3) on which the verification of the short circuit takes place by taking the whole part of the fraction :

with A _V the degree of ignition advance; d _i the number of engine degrees corresponding to the duration of a tooth (D _i ) of the flywheel (3)

d ₂₀ the number of the 20th flywheel tooth (3) corresponding to a top dead center.