EP2148978B1 - Method for indicating states of an electric component to an engine control device of an internal combustion engine - Google Patents

Description

The invention relates to a method for the feedback of states of an electrical component to an engine control unit of an internal combustion engine with a control unit of the electrical component having means for detecting errors and which is connected via a signal line to the engine control unit and receives a generated in the engine control unit PWM signal wherein the control unit pulls the signal line for feedback of data of the electrical component to the engine control unit to ground.

In the field of vehicle technology, it is increasingly demanded in recent times that electrical components such as pumps or actuators have the ability to report a feedback of states of the components to the engine control unit. Usually, these components are controlled via the engine control unit by means of pulse width modulation. This is done via a single existing signal line, which serves both for the transmission of the desired signal in the form of a PWM coding from the engine control unit to the control unit of the component and vice versa to be used, an optionally existing fault condition or actual state of the component to the engine control unit to transfer.

Such feedback of conditions for diagnosis are known in that the component pulls the signal line to ground if there is any error. This is detected by the engine control unit, as this serves as the master. At the same time, the engine control unit measures the voltage on the signal line, so that if the engine control unit wants to output a high level, but the line remains low due to the ground connection, this is an indication that either the component is malfunctioning or not shorted the line is. In the past, therefore, the switching of the signal line to ground by the electrical component has conventionally been used to tell the engine control unit that an error has occurred, for example US2005 / 210866 ,

A disadvantage of such an embodiment, however, is that only at the occurrence of any error this is reported back to the engine control unit, without being able to actually identify the error. Furthermore, there are no feedbacks regarding the actual state of the electrical component.

It is therefore an object of the invention to provide a method for reporting conditions of an electrical component to an engine control unit of an internal combustion engine, with which an error occurring in the electrical component is not only transmitted to the engine control unit, but this detected in the engine control unit, ie identified becomes. In addition, it should be achieved that, even without the occurrence of a fault, information about an actual state of the electrical component can be reported to the engine control unit.

This object is achieved by using the duration of the ground connection to identify the fault. This means that depending on the duration of a connection of the signal line with the ground this can be assigned to exactly one error, whereby the engine control unit can identify this error. For such a solution, only a minimal adaptation to the components used is necessary. This results in a flexible diagnostic functionality, in which only minimal resources in both the control unit of the electrical component and in the external engine control unit are required, since only in the engine control unit, a corresponding comparison code with respect to the length of the transmitted signal must be stored.

In a further embodiment of the invention, the duration of the ground connection is used in addition to the feedback of the actual value of the electrical component. The feedback of an error or the actual state of the electrical component can take place by definition according to successive. Accordingly, it makes sense to have such feedback regularly with you To carry out control of the electrical component. The coding of this actual value of the electrical component can, for example, be linear, so that an on-ground pull over a defined maximum period of for example one second would correspond to a 100% speed, half the time for example a 50% speed , As a result, a hitherto unknown feedback of an actual value of the electrical component to the engine control unit would be realized in a very simple manner.

Preferably, in a first time block, the signal line is pulled to ground for a predefined time in order to inform the control unit, which serves as the master, that a feedback occurs. This is necessary in order to distinguish possible problems from a protocol for error or actual status determination. Such disturbances are usually much shorter than this synchronization period.

In a subsequent second time block, the duration of the connection of the signal line to the ground serves as. Measure of the actual state of the electrical component if no error occurs, after which the connection is released from the component again. Accordingly, it could be stored in the engine control unit that there is a direct proportionality between the time duration of the ground connection in this second time block and the actual speed.

In addition, when an error occurs, the connection of the signal line with the ground is maintained until a period of time that identifies this fault has elapsed. An error detected by the control unit of the electrical component can thus be clearly identified by a corresponding deposit of a code in the engine control unit due to the duration of the ground connection. Each individual error detectable via the control unit is thus assigned exactly one defined time duration. Accordingly, with the least amount of electronic effort, such an identification of the errors can be made via the engine control unit.

In a further embodiment, the possible errors are classified and assigned to different groups, so that depending on the severity of the error extend the transmission times. Errors with similar consequences for the function of the electrical component are preferably combined into these groups.

Accordingly, upon release of the connection of the signal line from the control unit of the component during a first subsequent period of time to an error from a group of errors resulting in reduced operation of the electrical component, during a subsequent period of time an error is determined from a group of Errors of the electrical component closed and closed during a subsequent period of time on an error from a group of errors in the system, wherein the connection of the signal line to the ground is maintained until the time defined for the occurring error with the longest identifying period of time has expired. This ensures that in fact the most serious fault present is reported back to the engine control unit and appropriate action can be taken.

A particularly favorable embodiment results when the electrical component is an electromotively operated pump, in which the group of errors leading to a reduced operation of the pump is subdivided into a time block for a first speed limit, a time block for a second speed limit, a time block for dry run detection and a time block for power limitation. These time blocks serve as the first and not so serious set of mistakes.

Preferably, the group of faults of the electrical component in the case where the electrical component is an electromotive pump includes at least one time block for an over-current pumping fault. This pump error thus forms a second group of errors, which is queried for the first group of errors due to the greater weighting.

It is also advantageous when using a motor driven pump, if the group of faults in the system at least one time block for an overvoltage, a time block for a dry run shutdown and a Time block for a temperature shutdown includes. Such errors lead to a no longer given functionality of the system, so that a corresponding feedback would have to be made for example to a driver of a car via the engine control unit.

This method and the further process steps ensure feedback to the engine control unit about the state of the electrical component in a simple manner. By appropriate weighting of the transmitted errors, it is possible to initiate any necessary measures. In contrast to previously known embodiments, such a feedback can take place in the entire period or periodically, as long as no change in the control signal occurs. Also, the actual engine status can be made available to the engine control unit. For this, the effort in the external control unit is extremely low.

• Figur 1 zeigt ein typisches Protokoll eines erfindungsgemäßen Verfahrens zur Rückmeldung von Zuständen einer elektrischen Komponente am Beispiel einer Pumpe.
• Figur 2 zeigt den Ablauf des Verfahrens bei einer Nenndrehzahl der Pumpe von 50% ohne auftretende Fehler.
• Figur 3 zeigt das Protokoll bei Auftreten eines Überstromfehlers an der Pumpe.
• Figur 4 zeigt ein Verfahren zur Rückmeldung, bei dem je nach Anwendung unterschiedliche Modi wählbar sind.

The inventive method will be described in detail with reference to the figures below using the example of a motor driven pump.

• FIG. 1 shows a typical protocol of a method according to the invention for the return of states of an electrical component using the example of a pump.
• FIG. 2 shows the procedure of the procedure at a rated speed of the pump of 50% without errors occurring.
• FIG. 3 shows the log when an overcurrent fault occurs at the pump.
• FIG. 4 shows a method of feedback in which different modes are selectable depending on the application.

The method shown in the figures for the feedback of states of an electrical component to a control unit of an internal combustion engine are using the example of a built-in vehicle electric cooling water pump explained. In the vehicle, an engine control unit is arranged, which is connected via a signal line to a control unit of the cooling water pump. The control unit contains various means for detecting errors of the pump or for measuring operating conditions. Such circuit means are known. For example, the speed of a pump can be determined via non-contact sensors. The corresponding electrical circuits are also known, for example, for detecting overcurrent, overvoltages or the like.

This method now offers the possibility of exchanging as much information as possible via the signal line between the control unit of the cooling water pump and the engine control unit.

Only two states can be measured on the signal line, meaning that the state is high or the state is low, measured by the engine control unit. Usually, the control unit receives a pulse width modulated signal of the engine control unit, in which alternately the signal line has a high or a low level. The different duration of these times is used to control the speed of the pump. However, it is possible for the control unit of the cooling water pump via a corresponding circuit to pull the signal line to ground, whereby the engine control unit only receives a low signal, as long as the ground connection of the signal line is made.

In FIG. 1 Now, a typical control 1 of the engine control unit for electric motor driven cooling water pump is shown. For this purpose, the control unit is transmitted a PWM signal 2 via the signal line from the engine control unit. If the control unit receives such a signal, the pump is operated with the resulting speed until a possibly changed PWM signal 2 is transmitted via the signal line. There is now the possibility that the control unit pulls the signal line to ground. This can be done at fixed intervals, which can be chosen very small. This period of time 3, during which the signal line is grounded, is used for the feedback of states, one of which is shown enlarged accordingly.

For example, after expiration of a predetermined period of the PWM signal 2, the control unit of the pump pulls the signal line to ground. According to the example FIG. 1 This ground connection is first held 100 ms to tell the engine control unit that a feedback takes place. This period of time thus forms a synchronization time block 4. This is followed by an example one second long time block 5 for the actual speed. These two time blocks 4 and 5 are at least partially output at each feedback to be performed and are summarized in a group 6, after which the transmission ends, if no error occurs. Thus, the sole transfer of the group 6, the pump is fine.

This group 6 is now followed by a second group 7 for identifying a reduced operation of the pump. This consists in the present embodiment of four 100 ms time blocks, the time block 8 is used to detect a first speed limit, the time block 9 for detecting a second speed limit, the time block 10 for detecting a dry run and the time block 11 for detecting a power limit of the pump ,

This is followed by a group 12, in which pump errors are summarized, this group 12 in the present embodiment consists only of a time block 13 for detecting overflow or plausibility error 13, which is also 100 ms long.

Following the transmission of the group 12 errors, errors of a group 14 are transmitted, in which system errors are processed one after the other. Here is the first time block 15 of the system error identifying an overvoltage, as the second time block 16, the detection of dry running shutdown, as the third time block 17, the detection of a temperature shutdown and fourth time block 18, the identification of a lack of supply to the relay. These time blocks or groups of time blocks 4 to 1-8 thus form the maximum run of the feedback of states of the control unit of the water pump to the engine control unit.

At the end of this program, the control unit of the pump waits at least 0.5 to 1 s before another feedback takes place. This means that after the completion of the feedback, the normal connection of the signal line between the engine control unit and the control unit of the pump is restored.

In FIG. 2 It is now clarified how the process of the feedback takes place, if the pump is operated at a speed of 50% compared to the maximum speed. After switching the signal line to ground, first the sync time block 4 is transmitted, so that the engine control unit recognizes that a feedback occurs. Then, in the present embodiment, the connection with the ground is maintained for 0.5 seconds and then switched over again. This means for the engine control unit when defining a linear relationship that, since the signal of the time block 5 of the actual speed is only half of the possible total length of 1 s long, that the speed only 50% of the maximum speed. Since no error has been detected in the control unit, the connection of the signal line to ground ends at this point, so that via the signal line again the PWM signal 2 is transmitted from the engine control unit to the control unit of the water pump.

In FIG. 3 is shown for further explanation of how the program runs, if from the group 12 of the pump error an overcurrent by means of the time block 13 is detected by the control unit. In this case, the connection of the signal line to the ground is maintained until the time duration for the time block 4, so the synchronization time block and the time block 5 for the actual speed and for the time block 8 for the first speed limit, the time block for the second speed limit, the dry run detection time block 10, the power limit time block 11 and finally the overcurrent time block 13. This means that the connection to the mass is retained for 1.6 s. The engine control unit now recognizes that after 1.6 s, the normal connection of the signal line between the engine control unit and electrical component is restored and is able to determine from a stored in the engine control unit comparison code from this that obviously there is an overcurrent error, the on-ground Pull over a period of 1.6 s corresponds.

It also becomes clear that if an error occurs, no actual speed can actually be reported back. However, it remains possible for the engine control unit, for example, to pass on an appropriate error message to the driver of a vehicle.

If such a method is stored, it is of course also freely selectable in which modes such a system is to be used, for example, in different vehicles or internal combustion engines. So in the first error case 19, as in FIG. 4 illustrated a mode selected in which a log transmission takes place both when the pump is in order and when a fault occurs in the group 7 thus in reduced operation as well as when an error occurs in one of the groups 12, 14 so in pump or system errors. In line 20 it is shown that a transmission takes place only in the case of a pump or system error, ie in the case of a relatively serious error according to one of the groups 12 or 14.

In the following line 21, a third mode is described in which a transmission of the protocol in each case of error, so both an error occurs from the group indicating a reducing operator 7 as well as a pump error occurring or a system error so an error from one of Groups 12 or 14. Also, a complete deactivation of the transmission of the protocol according to line 22 is conceivable without having to make changes to hardware or software. This can be addressed to various customer needs, where you can switch between the different modes.

It becomes clear that a very flexible diagnostic functionality is created by such a method for the feedback of states, with only minimal additional resources in the component or the control unit or the engine control unit are required. The transmission of such a protocol, as described in the exemplary embodiment, remains compatible with the known prior art, although additional information, in particular with regard to the actual value, can be transmitted. A protocol monitoring is no longer necessary. In addition, an appropriate grouping ensures that the blind times of the controller are minimized. It should be clear that an adjustment depending on the electrical component used or other group divisions or another sequence in the processing of possible errors can be selected. It is also up to the individual user to decide to what extent all different groups to be defined are actually used or additional groups or time blocks are defined.

Claims (10)

1. A method for feedback of states of an electric component to an engine control device of an internal combustion engine, comprising a control unit for the electric component including a detection device configured to detect faults and connected to the engine control device via a signal line and receiving a PWM signal generated in the engine control device, wherein the control device ties the signal line to ground for a feedback of data of the electric component to the engine control device, characterized in that a duration of the connection to ground is used to identify the fault.
2. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in claim 1, characterized in that the duration of the connection to ground is used for the feedback of an actual value of the electric component.
3. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in one of claims 1 and 2, characterized in that in a first time block (4) of the feedback, the signal line is tied to ground for a predefined duration so as to communicate the occurrence of a feedback to the engine control device which is used as a master.
4. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in claim 3, characterized in that, in a second variable time block (5), the duration of the connection of the signal line to ground is used as a measure for an actual state of the electric component if no fault occurs, the connection then being released by the control unit of the electric component.
5. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in one of the preceding claims, characterized in that, upon occurrence of a fault, the connection of the signal line to ground is maintained until a lapse of a duration identifying the fault.
6. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in claim 5, characterized in that comprising possible faults are classified and are assigned to different groups (6, 7, 12, 14).
7. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in claim 6, characterized in that, upon a release of the connection of the signal line, the control unit of the component assumes, during a first duration after the release, a fault belonging to a group (7) of faults leading to a reduced operation of the electric component, said unit assuming, during a subsequent duration, a fault belonging to a group (12) of faults of the electric component, and, during a duration subsequent thereto, assuming a fault belonging to a group (14) of faults in the system, wherein the connection of the signal line to ground is maintained until the duration defined for the longest identifying duration of the faults that occurred has lapsed.
8. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in claim 7, characterized in that the electric component is an electromotoric pump wherein the group (7) of faults that lead to a reduced operation comprises is divided into a first rotational-speed limitation time block (8), a second rotational-speed limitation time block (9), a dry-run detection time block (10) and a performance limitation time block (11).
9. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in claim 7, characterized in that the electric component is an electromotoric pump wherein the group (12) of faults of the electric components comprises at least one time block (13) for a pump fault caused by overcurrent.
10. The method for feedback of states of an electric component to an engine control device of an internal combustion engine as recited in claim 7, characterized in that the electric component is an electromotoric pump wherein the group (14) of faults in the system comprises at least one occurring overvoltage time block (15), a dry-run switch-off time block (16) and a temperature switch-off time block (17).

Images