DE102017110689A1 - A method of determining a fault of a moment of an internal combustion engine in a hybrid powertrain - Google Patents

Abstract

The invention relates to a method for determining a fault of a torque of an internal combustion engine in a hybrid drive train of a motor vehicle. It will determine a moment of the internal combustion engine and a moment of an electric machine. A hybrid disconnect clutch is adjusted during charging of a rechargeable battery such that in a moment balance the friction torque is the only unknown. The friction torque M _F is calculated from the physical torque balance. The fault of the moment of the internal combustion engine is determined as the friction torque.

Description

The present invention relates to a method for determining a fault of a moment of an internal combustion engine in a hybrid drive train of a motor vehicle. More particularly, the present invention relates to a method of determining a fault of a moment of an internal combustion engine in a hybrid powertrain of a motor vehicle, the hybrid powertrain further comprising an electric machine connected downstream of the internal combustion engine in the hybrid powertrain, a hybrid disconnect clutch for selectively engaging or disengaging the internal combustion engine with the electric machine and an accumulator for storing electrical energy for the electric machine.

The present invention also relates to a computer program product that causes a controller to perform a method for determining a fault of a moment of an internal combustion engine in a hybrid powertrain of a motor vehicle. The present invention also relates to a motor vehicle having a computer program product.

From the prior art motor vehicles with hybrid drive and hybrid modules for drive trains of motor vehicles are known. Such motor vehicles have an internal combustion engine (internal combustion engine) and an electric machine. By means of the hybrid drive train it is ensured that the internal combustion engine can be coupled with the electric machine by means of a hybrid disconnect coupling. Likewise, the internal combustion engine can be decoupled with the hybrid disconnect from the electric machine. Further, the hybrid powertrain on a dual clutch, which serves to effect a technical coupling and uncoupling of the hybrid drive from a transmission of the vehicle. In other words, the hybrid disconnect clutch effects coupling between the electric machine and the engine, wherein the dual clutch then couples or decouples the hybrid powertrain with the transmission. Hybrid disconnect clutch and dual clutch form a triple clutch. The dual clutch comprises two partial clutches, which can be coupled in a separable manner with one transmission shaft each.

The moment of the internal combustion engine is not measured but estimated. An error is often displayed in the form of a constant offset. This offset can be learned via a software function and used for further clutch-specific adaptations, for example for the touch point or friction coefficient adaptation. Both methods open the clutch so that the drive and output rotate unevenly. In this case, the clutch torque is equal to the engine torque. A fault of the engine torque would also affect the result of the adaptation.

The engine torque is used to adapt the coefficient of friction of the hybrid disconnect clutch described above. When the engine torque has an error in the signal, the engine torque error translates into the adaptation of clutch specific parameters (eg, touch point or friction value) because the engine torque equals the clutch torque. The control of the hybrid disconnect clutch is adversely affected, so that it can interfere with the coupling and / or decoupling of the internal combustion engine with the electric machine. This error can be corrected by learning the deviation of the engine torque and entering it as a correction value into the input values of the clutch control.

From the prior art is also known that in motor vehicles with conventional engine drive without electric machine, the engine torque in the idling phase, so if the engine and the transmission are decoupled from each other, measured and the deviation of the engine torque is learned to zero as an offset.

However, in hybrid vehicles, the idling phase of the engine does not occur because the engine is shut down at standstill and also at low speed ranges, such as below about 10km / h. Thus, the failure of the engine torque can not be learned in idle phases and said low speed ranges of the internal combustion engine in motor vehicles with hybrid drive and so determined.

It is therefore an object of the present invention to provide a method for determining a fault of a moment of an internal combustion engine in a hybrid drive train of a motor vehicle, wherein the error is determined accurately and simply.

This object is achieved by a A method for determining a fault of a moment of an internal combustion engine in a hybrid powertrain of a motor vehicle, which method comprises the features of claim 1.

It is also an object of the present invention to provide a computer program product that causes a controller to perform such a method for determining a fault of a moment of an internal combustion engine in a hybrid powertrain.

This object is achieved by a computer program product comprising the features of claim 7.

The invention for determining a fault of a moment of an internal combustion engine in a hybrid drive train of a motor vehicle comprises a plurality of steps, which will be described below. First, the method is designed for a hybrid powertrain which, in addition to the internal combustion engine, further comprises an electric machine which is connected downstream of the internal combustion engine in the hybrid drive train. The hybrid powertrain also includes a hybrid disconnect clutch for selectively engaging or disengaging the internal combustion engine with the electric machine and an accumulator (battery) for storing electrical energy for the electric machine.

According to the invention, a moment Mc of the internal combustion engine and a moment M _E the electrical machine determined, preferably at the same time. The hybrid disconnect clutch is adjusted during charging of the accumulator so that in a moment balance M _B the friction torque M _F the only unknown is. Here is the friction torque M _F the friction torque of the internal combustion engine, the electric machine and the hybrid disconnect clutch. The moment balance M _B As summand of a zero sum, the moment Mc of the internal combustion engine comprises the amount | (M _E ) | of the moment M _E the electric machine and the friction torque M _F , so the moment balance M _B determined by the following equation: $${\text{M}}_{\text{B}}={\text{M}}_{\text{C}}-\left|{\text{M}}_{\text{e}}\right|-{\text{M}}_{\text{F}}=0$$

Then results according to the invention from the physical moment balance M _B the friction torque M _F from the following equation: $${\text{M}}_{\text{F}}={\text{M}}_{\text{C}}-\left|{\text{M}}_{\text{e}}\right|$$

Then, the error of the torque Mc of the internal combustion engine according to the invention as the friction torque M _F certainly.

In one embodiment of the method, a torque Msc of the hybrid disconnect clutch during driving of the motor vehicle is determined as a fixed offset O by addition of the offset O to or subtraction of the offset O from the moment Mc of the internal combustion engine: $${\text{M}}_{\text{SC}}={\text{M}}_{\text{C}}+{\text{O or M}}_{\text{SC}}={\text{M}}_{\text{C}}-\text{O}$$

In one embodiment, the torque offset adjustment may be accomplished by closing the hybrid disconnect clutch to charge the battery. In this case, the hybrid drive train is open to a transmission and at least one drive wheel of the motor vehicle. In particular, in one embodiment, a dual clutch of the hybrid powertrain is opened to the transmission. In this case, the dual clutch is designed for selectively coupling or decoupling the internal combustion engine and / or the electric machine with the transmission. As described above, the hybrid disconnect clutch and the dual clutch form a triple clutch. In particular, the dual clutch usually comprises two partial clutches. Each partial clutch can be separated in a separable manner with a different transmission shaft.

In another embodiment, the torque offset compensation is carried out in that the determined friction torque R _F between the internal combustion engine and the electric machine is adjusted by means of an adjustable slip of the double clutch.

In yet another embodiment, the torque offset compensation is performed by the moment Mc the internal combustion engine is increased suddenly and the resulting from this jump over torque with the moment M _E the electric machine is compensated, so that at any speed of the internal combustion engine the moment Mc the internal combustion engine with the moment M _E the electrical machine is adjusted.

The computer program product according to the invention causes a controller to carry out a method for determining a fault of a moment Mc of an internal combustion engine in a hybrid drive train of a motor vehicle, as described above.

• 1 eine schematische Ansicht eines Hybridantriebstrangs eines Kraftfahrzeugs gemäß einer Ausführungsform, bei dem das erfindungsgemäßen Verfahren zum Bestimmen eines Fehlers eines Moments einer Brennkraftmaschine in einem Hybridantriebstrang eines Kraftfahrzeugs angewendet werden kann;
• 2 ein Diagramm, in dem Beispielsverläufe für das Moment Mc der Brennkraftmaschine und das Moment M_E der elektrischen Maschine über die Zeit aufgetragen sind; und
• 3 ein Ablaufdiagramm für eine Ausführungsform des erfindungsgemäßen Verfahrens zum Bestimmen eines Fehlers eines Moments einer Brennkraftmaschine in einem Hybridantriebstrang eines Kraftfahrzeugs.

In the following, embodiments of the invention and their advantages with reference to the accompanying drawings will be explained in more detail. The proportions in the figures do not always correspond to the actual size ratios, as some shapes are simplified and other shapes are shown enlarged in relation to other elements for ease of illustration. It shows:

• 1 a schematic view of a hybrid powertrain of a motor vehicle according to an embodiment, wherein the inventive method for determining an error of a moment of an internal combustion engine in a hybrid powertrain of a motor vehicle can be applied;
• 2 a diagram in the example graphs for the moment Mc of the engine and the moment M _E the electric machine are applied over time; and
• 3 a flowchart for an embodiment of the inventive method for determining a fault of a torque of an internal combustion engine in a hybrid powertrain of a motor vehicle.

For identical or equivalent elements of the invention, identical reference numerals are used. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures, which are required for the description of the respective figure.

1 shows a schematic view of a hybrid powertrain 1 of a non-illustrated motor vehicle according to an embodiment, wherein the inventive method for determining an error of a moment Mc an internal combustion engine 2 in a hybrid powertrain 1 a motor vehicle of the invention can be applied. The location of each element (internal combustion engine 2 , electric machine 3 , Accumulator 4 , Generator 5 , Hybrid Disconnect Coupling 7 , Double coupling 9 , Control 10 ) to each other and to a transmission 6 and at least one drive wheel 8th is only very schematic in each case 1 indicated.

In the embodiment of the hybrid powertrain 1 to 1 is a serial hybrid powertrain 1 shown as known in the art. After the internal combustion engine 2 (Internal combustion engine) is the electric machine 3 arranged. An accumulator 4 (Battery) is used to store electrical energy for the electric machine 3 (Electric motor). A generator 5 is used to convert kinetic energy of at least one drive wheel 8th into electrical energy in the accumulator 4 stored and for the electric machine 3 can be used. The gear 6 is between the at least one drive wheel 8th and the powertrain 1 arranged or at one end of the hybrid powertrain 1 arranged that the other end with the internal combustion engine 2 is opposite.

As already described above, a hybrid disconnect coupling is used 7 for selectively coupling or decoupling the internal combustion engine 2 with the electric machine 3 , and a double clutch 9 of the hybrid powertrain 1 is used for selective coupling or decoupling of the internal combustion engine 2 and / or the electric machine 3 on the one hand with the transmission 6 on the other hand. The hybrid separation clutch 7 and the double clutch 9 form a triple clutch. The double clutch 9 comprises two partial clutches (omitted for reasons of simplification), which can each be coupled with a respective transmission shaft (also omitted for reasons of simplification).

In the illustrated embodiment according to 1 is a controller 10 provided a computer program product 11 includes. The computer program product 11 initiates the control 10 to the inventive method for determining an error of a moment Mc of an internal combustion engine 2 in the hybrid powertrain 1 of the motor vehicle according to one of the embodiments described above and below. This error with respect to the moment Mc of the internal combustion engine 2 can be corrected by learning the deviation of the engine torque Mc and as a correction value in the input values of the controller 10 concerning the couplings 7 . 9 flows.

The error regarding the moment Mc of the internal combustion engine 2 can in a driving situation only in vehicles with serial hybrid powertrain 1 occurs, namely during charging of the accumulator 4 acting as energy storage for the electric machine 3 serves. The charging takes place only when the hybrid disconnect clutch is closed 7 instead, taking the powertrain 1 to the gearbox 6 and the at least one drive wheel 8th is open. In this situation, the engine torque Mc and the electric motor torque are M _E known. Both moments Mc and M _E can be determined and are from the physical moment balance M _B when the friction torque M _F as the only unknown is assumed to balance to zero: $${\text{M}}_{\text{B}}={\text{M}}_{\text{C}}-\left|{\text{M}}_{\text{e}}\right|-{\text{M}}_{\text{F}}=0$$

In the moment balance M _B from equation 1 are three variables M _C . M _E and M _F , There are two variables of this M _C and M _E known. By dissolving after M _F can in this way the unknown friction torque M _F be determined: $${\text{M}}_{\text{F}}={\text{M}}_{\text{C}}-\left|{\text{M}}_{\text{e}}\right|$$

M _F is now considered the torque error of the internal combustion engine 2 which, physically speaking, the friction between internal combustion engine 2 and electric motor 3 represents.

The invention thus describes the determination of the friction torque M _F the combustion engine 2 while charging. The internal combustion engine delivers 2 the energy that passes through the electric motor 3 in generator mode in electrical energy converts and in a rechargeable battery 4 is stored.

In this situation, in the control of the hybrid disconnect clutch 7 and / or the dual clutch 9 the moment balance M _B changed so that the friction torque M _F can be determined as the only unknown. The electric motor torque M _E is negative and is subtracted from the engine torque Mc. The moment left over, so the difference Mc and | M _E |, is the friction torque M _F the internal combustion engine 2 , the hybrid disconnect clutch 7 and the electric motor 3 , This is important in situations when driving the motor vehicle, the clutch torque Msc from the moment Mc of the internal combustion engine 2 derive. It is added or subtracted as a fixed offset O: $${\text{M}}_{\text{SC}}={\text{M}}_{\text{C}}+{\text{O or M}}_{\text{SC}}={\text{M}}_{\text{C}}-\text{O}$$

In this case, the torque offset adjustment with closed hybrid disconnect clutch 7 for charging the accumulator 4 be executed, wherein the hybrid powertrain 1 to the gearbox 6 and the at least one drive wheel 8th of the motor vehicle is open. In particular, this can be the double clutch 9 of the hybrid powertrain 1 to the transmission 6 be opened.

Furthermore, the torque offset adjustment can be performed in driving situations where the torque applied to the powertrain 1 (from the electric machine 3 ) is known. For this purpose, the determined friction torque R _F between the internal combustion engine 2 and the electric machine 3 by means of an adjustable slip of the double clutch 9 adjusted.

Another possibility for the torque offset adjustment, during a normal drive, the moment Mc of the internal combustion engine 2 Increase abruptly and the resulting from this jump over torque with the moment M _E the electric machine 3 compensate, so that at any speed of the internal combustion engine 2 the moment Mc of the engine 2 with the moment M _E the electric machine 3 is adjusted. This should be the double clutch 9 in slippage to keep the vehicle in the stable driving state at a constant speed and to prevent unwanted acceleration of the motor vehicle.

In the illustration after 1 is a controller 10 with a computer program product 11 intended. The computer program product 11 initiates the control 10 to a method for determining an error of a moment Mc of the internal combustion engine 2 in the hybrid powertrain 1 of the motor vehicle according to one of the embodiments described above or below. In addition, the controller controls 10 the internal combustion engine 2 , the electric machine 3 , the accumulator 4 , the generator 5 , the hybrid disconnect clutch, the dual clutch 9 , The gear 6 and / or the at least one drive wheel 8th as indicated at least in part by the lines between these components.

2 shows a diagram in which example curves for the moment Mc the internal combustion engine and the moment M _E the electric machine over time t are applied. Essentially, both moments are Mc and M _E at least during charging of the battery at standstill of the vehicle, over time t constant. The difference from the moment Mc of the internal combustion engine 2 and the moment M _E the electric machine 3 is called the friction torque M _F the internal combustion engine 2 , the electric machine 3 and the hybrid disconnect clutch 7 accepted. The mistake of the moment Mc the internal combustion engine 2 is called the friction torque M _F determined as above and also in connection with 3 described below.

3 shows a flowchart for an embodiment of the method according to the invention for determining an error of a moment Mc of an internal combustion engine 2 in a hybrid powertrain 1 of a motor vehicle. The inventive method has several steps, as will be described below.

According to the invention in the steps 100 and 101 one moment Mc the internal combustion engine and a moment M _E the electrical machine determined, preferably at the same time. In step 102 becomes the hybrid disconnect clutch 7 during charging of the accumulator 4 set in such a way that in a moment balance M _B the friction torque M _F the only unknown is. Here is the friction torque M _F the friction torque of the internal combustion engine 2 , the electric machine 3 and the hybrid disconnect clutch 7 , The moment balance M _B includes as summands of a zero sum the moment Mc the internal combustion engine 2 , the amount | (M _E) | of the moment M _E the electric machine 3 and the friction torque M _F , so the moment balance M _B determined by the following equation: $${\text{M}}_{\text{B}}={\text{M}}_{\text{C}}-\left|{\text{M}}_{\text{e}}\right|-{\text{M}}_{\text{F}}=0$$

In step 103 then results according to the invention from the physical moment balance M _B the friction torque M _F from the following equation: $${\text{M}}_{\text{F}}={\text{M}}_{\text{C}}-\left|{\text{M}}_{\text{e}}\right|$$

In step 104 then becomes the fault of the moment Mc of the internal combustion engine 2 according to the invention as the friction torque M _F certainly.

In one embodiment of the method, a moment Msc of the hybrid disconnect clutch becomes 7 during driving of the motor vehicle as a fixed offset O by adding the offset O to or subtracting the offset O from the moment M _C the internal combustion engine 2 certainly: $${\text{M}}_{\text{SC}}={\text{M}}_{\text{C}}+{\text{O or M}}_{\text{SC}}={\text{M}}_{\text{C}}-\text{O}$$

As described above, the torque offset adjustment can be performed by different steps: by closing the hybrid disconnect clutch 7 for charging the accumulator 4 and opening the double clutch 9 of the hybrid powertrain 1 to the transmission 6 ; or by balancing the determined friction torque R _F between the internal combustion engine 2 and the electric machine 3 by means of an adjustable slip of the double clutch 9 ; or by a sudden increase in the torque Mc of the internal combustion engine 2 and compensating for the overmoment resulting from this jump with the moment M _E the electric machine 2 , so that at any speed of the internal combustion engine 2 the moment Mc of the engine 2 with the moment M _E the electric machine 3 is adjusted.

The invention thus enables the error of a moment Mc of an internal combustion engine 2 in a hybrid powertrain 1 of a motor vehicle in a simple and accurate manner.

Although the present invention has been described above with reference to an embodiment, it should be understood that various embodiments and changes can be made without departing from the scope of the present invention as defined in the appended claims.

For further features and advantages of the present invention, reference is expressly made to the disclosure of the drawings.

LIST OF REFERENCE NUMBERS

1

Hybrid powertrain

2

Internal combustion engine (internal combustion engine)

3

electric machine (electric motor)

4

Accumulator (battery)

5

generator

6

transmission

7

Hybrid clutch

8th

drive wheel

9

Double coupling

10

control

11

A computer program product

100

Determining the moment of the internal combustion engine

101

Determining the moment of the electric machine

102

Adjusting the hybrid disconnect clutch while charging an accumulator

103

Calculate the friction torque

104

Determining the error of the moment of the internal combustion engine

M _B

torque balance

M _C

Moment of the internal combustion engine (engine torque)

M _E

Moment of the electric machine

M _F

Friction torque of the internal combustion engine, the electric machine and the hybrid disconnect clutch

msc

Moment of the hybrid disconnect clutch

O

offset

Claims (7)

Method for determining a fault of a torque (Mc) of an internal combustion engine (2) in a hybrid drive train (1) of a motor vehicle, wherein the hybrid drive train (1) further comprises: an electric machine (3) that is connected to the internal combustion engine (2) in the hybrid drive train (1 ), a hybrid disconnect clutch (7) for selectively coupling or decoupling the internal combustion engine (2) with the electric machine (3), and an accumulator (4) for storing electrical energy for the electric machine (3); characterized by the following steps: determining a moment (Mc) of the internal combustion engine (2); Determining a moment (M _E ) of the electric machine (3); Adjusting the hybrid disconnect clutch (7) during charging of the accumulator (4) such that in a torque balance (M _B ), the torque (Mc) of the internal combustion engine (2), the amount | (M _E ) | the moment (M _E ) of the electric machine (3) and a Friction torque (M _F ) of the internal combustion engine (2), the electric machine (3) and the hybrid disconnect clutch (7) as Summanden a zero sum, so that the friction torque (M _F ) is the only unknown and the torque balance (M _B ) by the Equation: M _B = M _C - | M _E | - M _F = 0 is determined; Calculating the friction torque M _F = M _C - | M _E | from the physical moment balance (M _B ); and determining the error of the moment (Mc) of the internal combustion engine (2) as the friction torque (M _F ). Method according to Claim 1 comprising determining a torque (Msc) of the hybrid disconnect clutch (7) during the driving of the motor vehicle as a fixed offset (O) by adding the offset (O) to or subtracting the offset (O) from the torque (M _C ) of the internal combustion engine ( 2): M _SC = M _C + O or M _SC = M _C - O. Method according to Claim 2 comprising closing the hybrid disconnect clutch (7) to charge the accumulator (4), the hybrid powertrain (1) being open to a transmission (6) and at least one drive wheel (8) of the motor vehicle. Method according to Claim 3 in which a double clutch (9) of the hybrid drive train (1) is opened to the transmission (6), wherein the dual clutch (9) for selectively coupling or decoupling the internal combustion engine (2) and / or the electric machine (3) with the transmission ( 6) is designed. Method according to one of Claims 1 or 2 , wherein the determined friction torque (R _F ) between the internal combustion engine (2) and the electric machine (3) by means of an adjustable slip of the double clutch (9) is adjusted. Method according to one of Claims 1 or 2 , wherein the torque (Mc) of the internal combustion engine (2) is suddenly increased and the resulting from this jump over torque with the torque (M _E ) of the electric machine (3) is compensated, so that at any speed of the internal combustion engine (2) Moment (Mc) of the internal combustion engine (2) with the moment (M _E ) of the electric machine (3) is adjusted. A computer program product (11) for causing a controller (10) to perform a method of determining a fault of a moment (Mc) of an internal combustion engine (2) in a hybrid powertrain (1) of a motor vehicle according to any one of the preceding claims.

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