DE102006012858A1 - Internal combustion engine`s running smoothness determining method for vehicle, involves transferring control information of electrical machine to control device of internal combustion engine over vehicle bus - Google Patents

Abstract

The method involves exchanging signals over a vehicle bus (20) by using a control device (24). Control information of an electrical machine (14) is transferred to another control device (22) of an internal combustion engine (12) over the vehicle bus. Angle and oscillation information regarding an amplitude and position of a center of gravity of oscillation at the electrical machine and time information regarding the occurrence of the oscillation are included in the control information.

Description

was standing of the technique

DE 199 45 811 A1 refers to a method of detecting misfires. This is used in internal combustion engines application. In the proposed method, a measure of the rough running of the internal combustion engine is formed and compared with a threshold, which is dependent on the load of the internal combustion engine and wherein an exceeding of the threshold value is interpreted as a dropout. In addition to the dependence on the load, the threshold value is also considered dependent on the ignition angle and / or on the composition of the fuel / air mixture of the internal combustion engine. Furthermore, alternatively, the formation of the measure for uneven running can also take place depending on the ignition angle and / or the composition of the fuel / air mixture of the internal combustion engine and furthermore alternatively the activation / deactivation of the misfire detection depending on at least the ignition angle and / or the composition of the fuel / Air mixture of the engine take place. Taking account of load and ignition angles and possibly also of the composition of the fuel / air mixture, a value for the torque applied by the internal combustion engine is first determined and the threshold or the formation of the measure for the engine noise depends on the value for the torque applied by the internal combustion engine carried out.

In addition to the DE 199 45 811 A1 known methods, there are further methods with which the quality of combustion of an internal combustion engine can be determined on the basis of exhaust gas backpressure sensors, ion current signals or combustion chamber pressure sensors.

epiphany the invention

at Operation of an internal combustion engine in conjunction with at least an electrical machine, e.g. in conjunction with a starter-generator damper or As drive component of a hybrid drive such. a parallel hybrid drive can already present on the at least one electrical machine Signals from which angle information is retrieved, e.g. signals the electrical commutation as the current course of individual phases or also angular encoders, to determine the smoothness and the uneven running the internal combustion engine are used. In an electric damper can directly the control signals for damping the driveline damping provided that the machines, i. the internal combustion engine and the at least one electric drive closely coupled in the same Powertrain are included.

The proposed invention allows the signals of the control of Internal combustion engine with those of the electric machine such to couple that with these signals a diagnosis of the internal combustion engine with regard to the occurrence of combustion misfires can.

at the above-mentioned prior art method becomes Method, which on the detection of the uneven running or on the Recognition of misfiring relies on internal combustion engines considerably more difficult with increasing number of cylinders. A timely and clear detection of misfiring is therefore not more in all operating conditions the internal combustion engine possible.

at Use of an electrical machine such as e.g. of the above-mentioned starter-generator damper or at least one an electric drive in the context of a hybrid drive such. one Parallel hybrid drive, the electric machine can be used to dampen Vibrations are used. For parallel hybrid drives, e.g. can there existing serving as an electric drive at least one electric machine accordingly for vibration damping of Crankshaft of the internal combustion engine can be used. at Use of alternative methods, e.g. Exhaust back pressure sensor, Ion current signals or combustion chamber pressure sensors are additional partly not yet existing sensors required, the one Use of these procedures complicate.

The proposed according to the invention Method uses the already existing signals of the electrical Machine, which uses this for active vibration damping or the existing signals, that of the electrical commutation to serve the electric machine. These signals must be prepared and can via communication device such as e.g. a CAN bus or the like the control unit the internal combustion engine are provided so this corresponding error handling in the context of an OBD (on-board diagnosis) legislation can cause.

With an existing angle sensor and a fixed coupling of the electric machine to the crankshaft of the internal combustion engine, the identified vibration with center of gravity, based on the measured angular position and amplitude and based on the timing information of the center of gravity (time stamp) are transmitted to the engine control unit of the internal combustion engine. Inside the engine control unit, which is assigned to the internal combustion engine, the assignment of the error can be made to the corresponding cylinder of the internal combustion engine. With an already existing angle sensor and a fixed coupling between the internal combustion engine and the at least one electric machine can due to a known or learned angular position, via a spout detection in the control unit of the internal combustion engine or a synchronization of the ignition and injection at the start of the internal combustion engine, the identified vibration in terms of their Center of gravity and their amplitude as well as in terms of a temporal information of the center of gravity are transmitted to the engine control unit. Preferably, a common, synchronized time base of the control devices involved, ie, the control device of the internal combustion engine and the control device of the at least one electric machine with the use of a time stamp for the communication with respect to the vibration information is created. A common, synchronized time base can be realized by providing global time information using a TTP / C protocol, TTCAN protocol, FlexRay protocol or other timed communication. TTCAN, TTP / C and FlexRay protocols describe a timed communication, which unlike the conventional CAN is not event-based but deterministic and requires a common time base.

Further Is it possible, with the inventively proposed Method an individual comparison of the time information means Question and answer under consideration determine the term, using their own time base or with respect to the answer also a time difference Δ to the foreign time base can be determined. Furthermore, an additional line may be provided be on the transmit a signal is synchronous to the speed sensor of at least one electrical Machine is. An edge of this signal is from the processor of the control unit the internal combustion engine evaluated and in relation to the own speed detection set. This will both the speeds the at least one electric machine and the internal combustion engines compared to each other. Alternatively, a square wave signal from the control unit the internal combustion engine to the control unit of the at least one electric machine be sent.

Consists a preferably fixed coupling of the at least one electrical Engine to the crankshaft of the internal combustion engine, however, not or should a diagnosis be made, the assignment of the relative angular position of the at least one electric machine to the crankshaft of the internal combustion engine as a relative angular position be learned.

Should learning the relative angular position becomes a common, Synchronized time base provided. Under use this synchronized time base becomes the currently determined angle from the control unit of the at least one electric drive via communication such as e.g. over one CAN bus to the control unit the internal combustion engine shipped. There may optionally a time correction are made and the received angle information compared to the timestamp that an internally cached one Has angle. The difference of the obtained angle information is used to correct the angular positions in both control units. are the internal combustion engine and the at least one electrical Machine designed by a clutch as separable, the determination of the Difference of the angle information for the correction of the angular positions in the two controllers every time you close the clutch again.

drawing

Based the drawing, the invention will be explained in more detail below.

It shows:

1 a schematic representation of the essential components of a hybrid drive here the example of a parallel hybrid drive.

2 the flowchart for detecting a vibration information according to the inventive method proposed and

3 a flowchart for detecting the difference value determination in an angular position detection according to the inventive method proposed.

embodiments

The representation according to 1 is the schematic structure of a drive train, in particular a parallel hybrid powertrain for a vehicle to take.

An in 1 illustrated hybrid drive 10 , which is in particular a parallel hybrid drive, comprises a multi-cylinder internal combustion engine 12 that over a wave 16 with an electric machine 14 is coupled. At the electric machine 14 It may be the at least one electric drive of the hybrid drive 10 Act or one of the internal combustion engine 12 associated starter. The electric Ma machine 14 stands with a battery 18 in connection, which may be in the case of a starter to the 12-volt on-board battery or in the case of a hybrid drive as in 1 shown to be a traction battery that operates at a significantly higher voltage level.

The internal combustion engine 12 is a control unit 22 assigned, which via a first connection point 26 to a vehicle bus 20 is coupled, which may be, for example, a CAN bus. The electric machine 14 is also a control unit 24 assigned, which via a second connection point 28 with the vehicle bus 20 is coupled.

The control unit 22 for the internal combustion engine 12 is associated with both actuators A _I and with sensors S _I. The sensors S _i may be, for example, combustion chamber pressure sensors, knock sensors, angle sensors and the like, while the actuators A _{I may} be intake and exhaust valves of the respective cylinders, a throttle valve, exhaust gas recirculation valves and the like.

Also the control unit 24 , which of the electric machine 14 is assigned, has actuators A _J , S _J , the electric machine 14 assigned. With regard to the sensors, these may be speed or angular position transmitters with regard to the actuators A _J around exciter coils. As actuators A _j come next transistors, circuit breakers and possibly couplings in question; With regard to the sensors S _j , which are assigned to the at least one electrical machine, sensors for current measurement and voltage measurement or encoders and resolvers may be mentioned.

The representation according to 2 a flow chart of the inventively proposed method for detecting a vibration information can be seen. According to the schematic drawing in 1 are the internal combustion engine 12 and at least one electric machine 14 over the wave 16 firmly coupled together. Among the sensors S _J is a sensor which, in function of an angle sensor, the rotational position of the at least one electric machine 14 detected. About the wave 16 are the rotor of the at least one electric machine 14 and the crankshaft of the internal combustion engine 12 firmly coupled together. Due to the fixed coupling between the internal combustion engine 12 and the at least one electric machine 14 can be on a known learned angular position as a reference point, such as via the outlet detection of the controller 22 the internal combustion engine 12 or by synchronization of ignition and injection at the start of the internal combustion engine 12 learned or can be determined. Within a bandpass filtering 44 will after the start 42 the vibration detection 40 if necessary, a bandpass filtering of the angular signal detected by means of the angle transmitter is undertaken. As a result, a narrowing of the vibrations to be evaluated can be achieved so that only the oscillations with respect to amplitude and frequency that are relevant are detected. In a subsequent investigation 46 the center of gravity and amplitude of the vibration, the angle signal is processed and stored. This is followed by a determination 48 In the present context, "time stamp" is understood as meaning a time information at which the angle signal has occurred.

In one to the investigation 48 the "time stamp" of the center of gravity and the amplitude of the vibration subsequent step 50 an optional first evaluation of the stored oscillation takes place and then a relevance check 52 , If it turns out that the stored vibration is not relevant, it will start 42 backward branching, if the stored oscillation is relevant, a transfer takes place 54 , Within the transmission 54 the stored information with respect to the detected oscillation in terms of center of gravity, amplitude and "timestamp" to the in 1 illustrated engine control unit 22 transmitted. There is the assignment of the error to the corresponding cylinder of the multi-cylinder internal combustion engine 12 instead of.

Is the in 1 shown fixed coupling of the internal combustion engine 12 with the at least one electric machine 14 over the rigid wave 16 however, not, but the connection is realized as a clutch, so that the angular position of the internal combustion engine 12 to at least one electric machine 14 is variable, is a relative angular position of the two machines 12 . 14 determined to each other. For this purpose, a common synchronized time base of the control devices involved with use of a "timestamp" for the communication of the vibration information is required.This common synchronized time base can eg have a "global time" when using the TTP-C protocol, when using TTCAN, FlexRay or like or other timed communication can be obtained. In addition, an individual comparison of the time information by means of question or answer on the basis of a respective time base or with respect to the determination of the response time and a time difference to a foreign time base, taking into account the duration can be made. But the common, synchronized time base can also be transmitted via an additional line on which a signal is transmitted, which synchronously to the speed sensor of the min at least one electric machine 14 is to be realized. An edge of the signal transmitted on the additional line is from the processor of the controller 22 the internal combustion engine 12 evaluated and set in relation to the own speed detection. In a modification of the above alternative, the signal as a square wave signal from the control unit 22 the internal combustion engine 12 to the control unit 24 the at least one electric machine 14 be sent.

The representation according to 3 the method proposed according to the invention for calculating the difference value of the angular position can be taken as a flow chart. In the absence of a fixed coupling of the at least one electric machine 14 to the crankshaft of the internal combustion engine 12 , nonexistent wave 16 or also for purposes of diagnosis, the assignment of a relative angular position of the two machines 12 . 14 to be learned to each other. This is related to 2 previously mentioned common, synchronized time base required. Using this common, synchronized time base, according to the difference value determination 60 the angular position after the start 62 a synchronization 64 carried out, that is queried, whether the time information of the controller 24 the at least one electric machine 14 and the time information of the controller 22 the internal combustion engine 12 are synchronized. If this query is denied, the query will precede 64 backward branching, if yes, a temporary storage 66 made, in which the "own" angle information, this means the angular information of the crankshaft of the internal combustion engine 12 cached with the inclusion of a "time stamp".

Within a query 68 it checks if the control unit 22 the internal combustion engine 12 an angle information with time stamp from the at least one electric machine 14 has received.

Will the query 68 denies, again before the query 64 branched back in terms of synchronization; becomes the query 68 affirmed in terms of the received angle information, there is a delay correction 70 in the control unit 22 the internal combustion engine 12 , Within the runtime correction 70 the received angle is compared with the time stamp, with that in the control unit 22 the internal combustion engine 12 An angle was cached with the same time stamp.

After making the runtime correction 70 is the possibly determined differential angle to correct the angular position of the two control units 22 . 24 used. Are the controllers 22 . 24 separable by a clutch, this is performed again each time the clutch is closed, since a non-fixed connection changes in the angular position between the rotor of the at least one electric machine 14 and the crankshaft of the internal combustion engine 12 pulls.

In addition, there is also the possibility of temporarily suppressing an oscillation if a regulator intervention with respect to the oscillation damping exceeds a predefined threshold. This may possibly only in case of error on request of the controller 22 the internal combustion engine 12 be performed. Thus stands the control unit 22 the internal combustion engine 12 the possibility to analyze the unattenuated signal of the crankshaft in a conventional way and thus to use the existing misfire detection. This is an extension of communication on the vehicle bus 20 , which may be designed as a CAN bus, offered.

For the diagnosis described above, the proper function of the at least one electric machine 14 necessary, be it an electric motor within the in 1 schematically reproduced hybrid drive 10 be it one of the internal combustion engine 12 assigned starter generator. This means that of the at least one electric machine 14 torque generated at constant control of this sufficiently constant over a revolution of the electric machine 14 should be. For this purpose, the at least one electric machine 14 the sensors S _J associated with which the electric machine 14 can be examined for their proper function. Should these diagnostics make a mistake on the electrical machine 14 can give about status information from the electric machine 14 to the control unit 22 the internal combustion engine 12 the misfire detection is blocked. With the sensors S _J , the electric machine 14 when used as an electric drive within the hybrid drive 10 with separate coupling to the internal combustion engine 12 in the operating mode "electric driving" to the output of a uniform rotation to be monitored because the failure mechanisms within the electric machine 14 Not too sporadic, but would lead to uniformly repeated torque fluctuations, it is possible to distinguish these fluctuations well from suggestions by the drive train. In addition, the at least one electric machine 14 be diagnosed with output stage monitoring, with current monitoring, with comparison of the individual phases to each other and the rate of current rise in the individual phases. Consists between the internal combustion engine 12 and the at least one electric machine 14 no fixed coupling in the shape of the shaft 16 according to 1 but is between these two machines 12 . 14 installed a separating clutch, the separating clutch can also be monitored for uncontrolled slip. Uncontrolled slip on the separating clutch can lead to torque fluctuations on the one hand and, on the other hand, the reference systems of the electrical machine 14 and the internal combustion engine 12 constantly shifting against each other. Therefore, it is desirable to constantly adjust the reference systems and to interpret a change with closed disconnect clutch as a clutch error. Such a coupling error is also for switching off the misfire detection by evaluating the angle or vibration signals of the electric machine 14 to lead.

The previously known and used misfire detection methods for internal combustion engines 12 have problems with the reliability of the received signals, especially at low load and high speeds. To remedy this problem, in a hybrid drive 10 the underlying operating strategy avoids these areas in terms of the "purely electric driving" and "hybrid driving" modes of deployment. For parallel hybrids, this can be done, for example, by allowing small loads, ie the requirement of low torques by the driver, alternately from the electric machine 14 be taken over or the electric machine 14 the internal combustion engine 12 additionally charged as a generator.

Claims (10)

Method for determining the smoothness of an internal combustion engine ( 12 ), the at least one electric machine ( 14 ), in particular within a hybrid drive ( 10 ), which is a control unit ( 22 ) for the internal combustion engine ( 12 ), at least one control device ( 24 ) for the at least one electrical machine ( 14 ), which via a vehicle bus ( 20 ) Exchange signals, characterized in that the control information of at least one electric machine ( 14 ) via the vehicle bus ( 20 ) to the control unit ( 22 ) of the internal combustion engine ( 12 ) is transmitted. A method according to claim 1, characterized in that the control information angle and vibration information with respect to the amplitude and center of gravity of the vibration and a time information regarding the occurrence of the vibration at the at least one electric machine ( 14 ). Method according to claim 1, characterized in that rotational uniformity of the at least one electric machine ( 14 ) for switching off and / or correcting misfire detection in the control unit ( 22 ) of the internal combustion engine ( 12 ) is taken into account. A method according to claim 2, characterized in that the vibration information at a known or learned angular position via an outlet detection of the control device ( 22 ) of the internal combustion engine ( 12 ) or synchronization of ignition and injection at the start of the internal combustion engine ( 12 ) be transmitted. A method according to claim 1, characterized in that at variable angular position between the internal combustion engine ( 12 ) and the at least one electrical machine ( 14 ), a relative angular position between the internal combustion engine ( 12 ) and the at least one electrical machine ( 14 ) using a control device ( 22 ) and ( 24 ) common synchronized time base is determined. Method according to Claim 5, characterized in that the common synchronized time base contains time information for the communication of the control devices ( 22 . 24 ) on the vehicle bus ( 20 ). A method according to claim 5, characterized in that the common synchronized time base is realized by time-controlled communication using TTP / C protocol, TTCAN or FlexRay, or an individual comparison of the time information by question and answer at their own time base in the control units ( 22 . 24 ) taking into account the transit time or on an additional line to the speed sensor of the at least one electric machine ( 14 ) synchronous signal is sent. A method according to claim 7, characterized in that an edge of the signal transmitted on an additional line signal in the processor of the control unit ( 22 ) of the internal combustion engine ( 12 ) is evaluated and in relation to the detected there speed information of the internal combustion engine ( 12 ) is set. Method according to claims 3 and 5, characterized in that after a time correction ( 70 ) of the angle signals of the at least one electrical machine ( 14 ) the received angle from the at least one electrical machine ( 14 ) with a time stamp of one in the control unit ( 22 ) of the internal combustion engine ( 12 ) buffered angle signal is compared with an identical timestamp. A method according to claim 9, characterized ge indicates that the difference of the angle information of internal combustion engine ( 12 ) and the at least one electrical machine ( 14 ) for correcting the angular position in the two control devices ( 22 . 24 ) is used.