DE102011080859A1 - Method and device for monitoring a control device for operating an engine system - Google Patents

Abstract

The invention relates to a method for monitoring the operation of a drive motor (2), comprising the following steps: - activating the drive motor (2) with a manipulated variable (S) which is generated as a function of an external specification (FWM) in accordance with a control function; Monitoring the manipulated variable (S) by a threshold comparison with a manipulated variable threshold value (MTHR), wherein the manipulated variable threshold value (MTHR) is generated as a function of a manipulated variable request generated by a monitoring function and a manipulated variable offset (MOffset), wherein the monitoring function represents an independent simulation of the actuation function, wherein the manipulated variable offset (MOffset) is selected variable depending on an operating range of the drive motor (2).

Description

Technical area

The present invention relates to drive systems for motor vehicles, in particular to methods for monitoring a drive torque request for a drive motor of a motor vehicle.

State of the art

In engine systems with internal combustion engines for driving motor vehicles, the internal combustion engines are usually controlled by means of engine control units in order to achieve a desired drive torque, i. H. a driver desired torque given by a driver to provide by the drive motor. In addition to the driver's desired torque in the engine control unit and other torque requirements, such as torque requirements for the shift assistance, the idle control and the Jerk damper function taken into account to determine a control torque, which is converted into appropriate control variables for the engine controlling controller, so that the corresponding moment is provided , For example, the manipulated variable torque in a diesel engine u. a. converted into an amount of fuel to be injected.

To prevent unwanted acceleration of the vehicle, the function of the engine control unit is permanently monitored. For this purpose, an actual torque provided by the internal combustion engine is compared in the engine control unit with a separately determined torque threshold value and an error reaction is triggered if the actual torque exceeds the torque threshold value.

In order to prevent misdetection during error-free operation, an offset is taken into account, i. H. the torque threshold value is set higher by an amount determined by the offset than the value of the actual torque expected in normal operation. For small errors in the provided actual torque and / or the requested driver's desired torque and / or other torque requests so the offset can prevent erroneous detection of a malfunction. In particular, in overrun error detection with such a torque monitoring is not possible because the preset offset is usually too large, so that occurring during the overrun error can not be detected. So far, errors that occur in overrun, detected with a separate thrust monitoring.

Disclosure of the invention

According to the invention, a method for monitoring a drive torque provided by a drive motor according to claim 1 and a device, an engine system and a computer program product according to the independent claims are provided.

Further advantageous embodiments of the present invention are specified in the dependent claims.

An idea of the above method is to provide a monitoring function in which a moment threshold is provided with an offset on a moment level, wherein the offset for better error discrimination in the overrun operation of the internal combustion engine is reduced in a overrun operating range. This makes it possible to transfer the known behavior of the thrust monitoring in overrun to the torque monitoring.

Disadvantages of the fault detection in the thrust monitoring are a high speed offset and a long reaction time. These disadvantages are transferred to the fault detection range of the torque monitoring with a lower speed offset and a lower reaction time. In particular, the above method provides, when detecting a pushing operation, to reduce the offset for determining the torque threshold value by an applicative value, in order to ensure more accurate error detection in overrun mode, ie. H. in a low speed, low load operating range.

• – Ansteuern des Antriebsmotors mit einer Stellgröße, die abhängig von einer externen Vorgabe gemäß einer Ansteuerfunktion generiert wird;
• – Überwachen der Stellgröße durch einen Schwellenwertvergleich mit einem Stellgrößenschwellenwert, wobei der Stellgrößenschwellenwert abhängig von einer mithilfe einer Überwachungsfunktion generierten Stellgrößenanforderung und einem Stellgrößenoffset erzeugt wird, wobei die Überwachungsfunktion eine unabhängige Nachbildung der Ansteuerfunktion darstellt,

wobei der Stellgrößenoffset abhängig von einem Betriebsbereich des Antriebsmotors variabel gewählt wird.According to a first aspect, a method for monitoring the operation of a drive motor is provided. The method comprises the following steps:

• - Driving the drive motor with a manipulated variable, which is generated depending on an external specification according to a drive function;
• Monitoring the manipulated variable by means of a threshold comparison with a manipulated variable threshold value, wherein the manipulated variable threshold value is generated as a function of a manipulated variable request and a manipulated variable offset generated by means of a monitoring function, wherein the monitoring function represents an independent simulation of the actuation function,

wherein the manipulated variable offset is variably selected depending on an operating range of the drive motor.

Furthermore, the manipulated variable a Stellmoment, the manipulated variable threshold a Torque threshold and the manipulated variable offset correspond to a torque offset.

According to another embodiment, the manipulated variable offset may be generated by adding a correction variable to a relative offset value generated from an offset function, the correction variable assuming a first predetermined correction value when the drive motor is in a predetermined operating range.

In particular, the predetermined operating range may correspond to a coasting operating range, which is given in particular when the external specification specifies that the drive motor should not provide any drive torque.

It can be provided that the first correction value is a defined value or an operating-point-dependent value.

Furthermore, the correction quantity may assume a second predetermined correction value when the drive motor is outside the predetermined operating range.

The second correction value may correspond to a specified value and in particular be 0.

• – den Antriebsmotor mit einer Stellgröße anzusteuern, die abhängig von einer externen Vorgabe gemäß einer Ansteuerfunktion generiert wird;
• – die Stellgröße durch einen Schwellenwertvergleich mit einem Stellgrößenschwellenwert zu überwachen, wobei der Stellgrößenschwellenwert abhängig von einer mithilfe einer Überwachungsfunktion generierten Stellgrößenanforderung und einem Stellgrößenoffset erzeugt wird, wobei die Überwachungsfunktion eine unabhängige Nachbildung der Ansteuerfunktion darstellt, und
• – den Stellgrößenoffset abhängig von einem Betriebsbereich des Antriebsmotors variabel einzustellen.

In another aspect, an apparatus for monitoring the operation of a drive motor is provided, the apparatus being configured to:

• - to drive the drive motor with a manipulated variable, which is generated depending on an external specification according to a drive function;
• To monitor the manipulated variable by means of a threshold comparison with a manipulated variable threshold value, wherein the manipulated variable threshold value is generated as a function of a manipulated variable request and a manipulated variable offset generated by a monitoring function, wherein the monitoring function represents an independent simulation of the actuation function, and
• - Set the manipulated variable offset variable depending on an operating range of the drive motor.

In another aspect, an engine system having a drive motor and the above apparatus is provided.

According to another aspect, there is provided a computer program product including program code which, when executed on a data processing device, performs the above method.

Brief description of the drawings

Preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

1 a schematic block diagram of an engine system; and

2 a functional representation for generating a torque threshold for limiting a predetermined by a control unit actuating torque.

Description of embodiments

1 schematically shows an engine system 1 with a drive motor 2 , which can be controlled via one or more manipulated variables S for providing a predetermined drive torque. The manipulated variable S can be determined, for example, from a requested actuating torque or from an indication of a drive torque to be provided. For example, the drive motor 2 represent an internal combustion engine. In the case of a diesel engine, the manipulated variable S may indicate an amount of fuel to be injected. In a gasoline engine, the manipulated variable S may indicate a position of a throttle valve for controlling the air supply to the cylinders of the internal combustion engine.

The manipulated variable S can be determined from the information about the drive torque to be provided in a motor control unit 3 , in particular in a manipulated variable block 31 , to be generated. The drive torque to be provided is from a predetermined driver desired torque FWM, which can be derived for example from a position of an accelerator pedal, and other external variables, such as torque requirements of additional equipment, such. As an air conditioner, a transmission and the like, in a control block 32 the engine control unit 3 generated according to a conventional drive function. The determination of the drive torque M _{B to be provided} according to the drive function takes place in the control block 32 in a known manner and it is not discussed here in detail on the functions for its determination.

It is still a monitoring block 33 provided that the proper functioning of the control block 32 is checked by the statement about the drive torque M _{B to} be provided by means of a separately determined according to a monitoring function torque threshold M _{THR is} checked. The monitoring block 33 can with the control block 32 be formed in a common control unit or with the same microcontroller or separately.

The monitoring block 33 generated depending on an operating point of the drive motor 2 the torque _{threshold value} M _THR as manipulated variable threshold value. By means of the torque _threshold value M _thr , the drive torque to be provided is monitored and an error is detected when the drive torque to be provided exceeds the torque _threshold value M _thr . If this is the case, an error reaction is started, which is a signaling of an error and / or the initiation of an emergency operation or a shutdown of the drive motor 2 can cause.

If an error is detected, the monitoring unit controls 33 the manipulated variable block 31 in a corresponding manner to the drive of the drive motor 2 to interrupt with the manipulated variable S or to generate a manipulated variable S according to an error function, if necessary, not taking into account the drive torque M _{B to be provided} . For example, the monitoring unit 33 as an error function a speed limitation to a limit speed of 1500 rpm by appropriate control of the manipulated variable block 31 perform if an error in the generation of the manipulated variable S by the control block 32 has been recognized.

In 2 is a functional diagram illustrating the function for generating the torque _threshold M _thr in the monitoring _block 33 shown. In a moment map block 21 are the requested moments, such as the driver's desired torque FWM, which can be derived for example from an accelerator pedal position, and other additional moments ZM ₁ , ZM ₂ , ZM ₃ , converted into an entire torque request M _A , from which the torque _threshold M _thr can be generated.

The torque request M _A is a summer 22 where the torque request M _A a variable torque _offset M _{offset is} added to determine the torque _{threshold value} M _thr as the sum.

The torque _threshold M _thr becomes a selection block 23 fed. The selection block 23 decides if the current moment request M _{B of} the control block 32 is checked with respect to the torque _threshold M _thr or, when an active coasting operation is detected, which is indicated by a thrust-active signal SAS, is checked with respect to a torque _{threshold value} of 0 (M _thr = 0). On the selection block 23 can be omitted if it is ensured that the of the momentum block 21 generated torque request in the active overrun mode is 0 and the variable torque _offset M _offset as _{setpoint offset} in overrun also assumes 0.

The push-active signal SAS then becomes active, ie it switches the selection element 23 such that a torque _threshold M _thr of 0 is output if all conditions exist for a valid overrun operation. Conditions for an active overrun operation may be that an accelerator pedal is not actuated (ie the drive motor does not require a drive torque due to the external specification) that the idle control is not active and / or that there is no external torque request. Further conditions for an activated thrust-active signal SAS can be provided.

As long as the thrust-active signal SAS is not active, the torque _{threshold value} M _{thr is} generated as the sum of the torque request M _A and the torque _offset M _offset .

The torque _offset M _offset is calculated using an offset map 24 from an operating point specification of the drive motor 2 generated. The operating point indication may be determined as a load L in the form of a currently provided drive torque and an indication of a speed n. Other parameters for determining the operating point are also possible.

The offset map 24 provides at its output a relative torque _offset rM _offset , which is first a subtraction element 25 is supplied. In the subtraction element 25 an offset correction value rk _{orr is} subtracted from the relative torque _offset value rM _offset to reduce the relative torque _offset value rM _offset and provide a corrected relative torque offset _value rM _{Offset_korr} .

In a conversion block 26 the relative magnitude of the corrected relative torque offset _value rM _{Offset_Korr} is converted to the torque _offset M _offset by multiplication with a predetermined maximum torque which can be provided by the internal combustion engine and to the summing element 22 fed.

Depending on an overrun signal SS, which indicates whether the drive motor is operated in the overrun operating range, a first correction _value r _Korr or a second correction value is sent to the subtraction _element as a relative correction factor 25 created. The overrun signal SS, in contrast to the thrust-active signal SAS, indicates that there may be a coasting operation. Therefore, the overrun signal SS is already active earlier before taking over the overrun because the number of criteria for determining overrun is reduced over the number of criteria necessary to activate the overrun active signal SAS. In particular, it can be stated that the drive motor is in the overrun operating range if no drive torque is required by the external specification (driver desired torque).

The push-active signal SAS is then active, for example, and leads to the application of the relative correction _value r _Korr to the subtraction element 25 when the accelerator pedal position is 0 and this position has been optionally held for a certain debounce time. Other conditions, such as an intervention of an idle controller and the like, are not checked here. As a result, it is possible to activate the relative correction value r _Korr for reducing the relative torque _offset rM _offset before an active coasting operation, indicated by the thrust-active signal SAS, by the engine control unit 3 has been recognized.

The relative correction value r _Korr may be a fixed value which subtractively reduces the relative torque _offset rM _offset . Alternatively, the relative correction _value r _{Korr may} also be a fixed predetermined factor. Alternatively, the relative correction _value r _Korr can be generated via a (not shown) correction value map, for example, depending on an operating point (load, speed and the like) of the drive motor 2 ,

Claims (10)

Method for monitoring the operation of a drive motor ( 2 ), with the following steps: - driving the drive motor ( 2 ) with a manipulated variable (S), which is generated according to an external specification (FWM) in accordance with a control function; - monitoring the control variable (S) by a threshold comparison with a manipulated variable threshold value (M _THR), the manipulated variable threshold value (M _THR) is generated as a function generated by a using a monitoring function manipulated variable request, and a manipulated variable Offset (M _offset), wherein the monitoring function of an independent replica of the Ansteuerfunktion represents, characterized in that the manipulated variable _offset (M _offset ) depends on an operating range of the drive motor ( 2 ) is chosen variable. Method according to Claim 1, wherein the manipulated variable (S) corresponds to an actuating torque, the manipulated variable threshold value (M _THR ) corresponds to a torque threshold value and the manipulated variable _offset (M _offset ) corresponds to a torque _offset . The method of claim 1 or 2, wherein said manipulated variable Offset (M _offset) is generated by a generated from an offset function relative offset value (rM _offset) a correction amount (r _corr) is added, the correction amount (r _corr) a first predetermined correction value assumes when the drive motor ( 2 ) is in a predetermined operating range. Method according to claim 3, wherein the predetermined operating range corresponds to a pushing operating range, which is given in particular when the external specification specifies that the drive motor ( 2 ) should provide no drive torque. The method of claim 3 or 4, wherein the first correction value is a predetermined value or an operating-point-dependent value. Method according to one of claims 3 to 5, wherein the correction quantity (r _korr ) assumes a second predetermined correction value when the drive motor ( 2 ) is outside the predetermined operating range. The method of claim 6, wherein the second correction value corresponds to a predetermined value and is in particular 0. Device for monitoring the operation of a drive motor ( 2 ), the device being designed to: - drive the motor ( 2 ) with a manipulated variable (S), which is generated depending on an external specification according to a drive function; To monitor the manipulated variable (S) by means of a threshold comparison with a manipulated variable threshold value (M _THR ), wherein the manipulated variable threshold value is generated as a function of a manipulated variable request generated by a monitoring function and a manipulated variable _offset (M _offset ), wherein the monitoring function represents an independent simulation of the actuation function, and - the manipulated variable _offset (M _offset ) depending on an operating range of the drive motor ( 2 ) variable. Engine system ( 1 ) with a drive motor ( 2 ) and the device according to claim 8. A computer program product containing program code which, when executed on a data processing device, performs the method of any one of claims 1 to 7.

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