DE102019132445A1 - Method for operating a drive device of a hybrid vehicle - Google Patents

Abstract

The invention relates to a method for operating a drive device of a hybrid vehicle, wherein the drive device comprises an internal combustion engine and an electric motor, and wherein the hybrid vehicle has auxiliary consumers that can be powered, and wherein a load point shift of the internal combustion engine is carried out in a warm-up mode during operation of the drive device, the load point shift being limited and wherein the limitation of the load point shift is determined with the aid of a torque (ICE) of the internal combustion engine, a driver load (FL) of a driver operating the hybrid vehicle and a charging torque (LM) of the electric motor, an amount of a difference between the driver load (FL) and the loading torque (LM) is determined, and if the torque (ICE) is greater than the amount of the difference between the driver load (FL) and the loading torque (LM), an operation of the drive device in an area with an impermissible load point shift (2) is detected.

Description

The invention relates to a method for operating a drive device of a hybrid vehicle according to the preamble of claim 1.

Hybrid vehicles are known and, in addition to a drive unit in the form of an internal combustion engine, have a further drive unit in the form of an electric motor. The electric motor can be operated to support the internal combustion engine when the hybrid vehicle is in operation. It is also possible to operate the hybrid vehicle solely with the aid of the electric motor. If the electric motor is not intended to output power in an operating mode of the hybrid vehicle, it is possible to pass on excess torque from the internal combustion engine to the electric motor and thus charge it, or in other words, kinetic energy is converted into electrical energy and thus recuperated. The internal combustion engine drives the hybrid vehicle and the electric motor. With the help of the electric motor, which works as a generator in this state, electrical energy can be generated or converted into electrical energy in the fuel burned by the internal combustion engine and stored in a storage device, for example a battery, of the drive train and / or at least one electrical consumer a drive train of the hybrid vehicle and / or the hybrid vehicle. Since a power provided by the internal combustion engine is thus partly used to drive the hybrid vehicle and partly to generate the electrical energy, a load point shift of the internal combustion engine can be carried out so that the internal combustion engine can be operated at a particularly economical operating point.

From the pamphlet DE 10 2013 224 677 A1 a method for operating a drive device of a hybrid vehicle emerges, an internal combustion engine being monitored exclusively with the aid of internal combustion engine variables and a load point shift of the internal combustion engine shortly after a cold start of the internal combustion engine is disclosed.

The object of the present invention is to specify an improved method for operating a drive device of a hybrid vehicle.

The object is achieved according to the invention with a method for operating a drive device of a hybrid vehicle with the features of claim 1. Advantageous refinements with expedient and non-trivial developments of the invention are specified in the respective subclaims.

A method according to the invention for operating a drive device of a hybrid vehicle is designed to detect an operation of the drive device in an operating range of the same with a permissible load point shift or an impermissible load point shift. The drive device comprises an internal combustion engine and an electric motor, and the hybrid vehicle has auxiliary consumers that can be powered. In a warm-up operation of the drive device, a load point shift of the internal combustion engine can be carried out, the load point shift being limited. The limitation of the load point shift is determined with the aid of a torque of the internal combustion engine, a driver load of a driver operating the hybrid vehicle and a charging torque of the electric motor, an amount of a difference between the driver load and the charging torque being determined and provided that the torque of the internal combustion engine is greater than that Amount of the difference between the driver's load and the loading torque, an operation of the drive device in a range with an impermissible load point shift is detected. The advantage can be seen in a simple method, since all the torques required to determine the operating range are already available in a control unit of the motor vehicle for operation of the motor vehicle. In other words, data that have already been determined can continue to be used during operation of the motor vehicle to determine the operating range that is permissible or impermissible for a load point shift, and no additional measures, such as installing additional sensors, have to be undertaken.

Avoiding a load point shift in an impermissible operating range of the internal combustion engine can be seen in a possible increase in emission values of the internal combustion engine, since with poor, or in other words low, efficiency of the internal combustion engine, its consumption increases, which also increases its emissions. In order to reduce emissions, it is therefore advantageous to limit the load point shift in the warm-up mode.

In one embodiment of the method according to the invention, an offset value is provided to determine the relationship between the torque of the internal combustion engine and the amount of the difference between the driver load and the loading torque, the offset value being the amount of the difference between the driver load and the Loading moment is added. With the aid of this offset value, torque fluctuations which would falsify a determination of the relationship between the torque of the internal combustion engine and which the amount of the difference between the driver load and the charging torque can be limited.

• 1 in einem Moment-Zeit-Diagramm eine Drehmomentverlauf über der Zeit einer Verbrennungskraftmaschine, von Nebenverbrauchern und Lademoment einer Elektromaschine gemäß dem Stand der Technik,
• 2 in einem prinzipiellen Moment-Zeit-Diagramm Drehmomentlinien der Verbrennungskraftmaschine, einer Fahrerlast und das Lademoment bei einem Betrieb einer Antriebseinrichtung bei positiver Fahrerlast bei zulässiger und unzulässiger Lastpunktverschiebung,
• 3 in einem prinzipiellen Moment-Zeit-Diagramm Drehmomentlinien der Verbrennungskraftmaschine, einer Fahrerlast und das Lademoment bei einem Betrieb der Antriebseinrichtung ohne Fahrerlast bei zulässiger und unzulässiger Lastpunktverschiebung, und
• 4 in einem prinzipiellen Moment-Zeit-Diagramm Drehmomentlinien der Verbrennungskraftmaschine, einer Fahrerlast und das Lademoment bei einem Betrieb der Antriebseinrichtung bei negativer Fahrerlast bei zulässiger und unzulässiger Lastpunktverschiebung.

Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and on the basis of the drawing. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the combination specified, but also in other combinations or alone, without the scope of Invention to leave. Identical or functionally identical elements are assigned identical reference symbols. Show it:

• 1 in a torque-time diagram, a torque curve over the time of an internal combustion engine, secondary consumers and charging torque of an electric machine according to the prior art,
• 2 In a basic torque-time diagram, torque lines of the internal combustion engine, a driver's load and the loading torque when a drive device is operated with a positive driver load with permissible and impermissible load point shifts,
• 3rd In a basic torque-time diagram, torque lines of the internal combustion engine, a driver load and the loading torque when the drive device is operated without driver load with an allowable and an inadmissible load point shift, and
• 4th In a basic moment-time diagram, torque lines of the internal combustion engine, a driver load and the loading torque when the drive device is operated with a negative driver load with an allowable and an inadmissible load point shift.

A motor vehicle not shown in more detail in the form of a hybrid vehicle includes an internal combustion engine and an electric motor in its drive train. The electric motor is connected to the internal combustion engine via a clutch, with the clutch being able to be closed or opened, in other words disconnected.

When the clutch is closed, the internal combustion engine can operate the electric motor as a generator. The electric motor can also drive the internal combustion engine. When the clutch is disengaged, the motor vehicle is driven exclusively by the internal combustion engine; the electric motor is not operated. There is also the possibility of parallel operation of the internal combustion engine and the electric motor. When operating the electric motor as a generator, thus in charging mode and taking up a charging moment LM Care must be taken to ensure that a load point shift in warm-up operation of the internal combustion engine is limited in order to achieve limited emission values.

In 1 are shown in a torque-time diagram torque curves over time of the internal combustion engine, secondary consumers and a charging torque of an electric machine as a function of a cooling water temperature according to the prior art. In this process, the load point shift is carried out depending on the cooling water temperature. With a so-called cold start with a cooling water temperature TK for example from 20 ° C, the load point shift is limited to so-called secondary consumers NV (e.g. alternator, air conditioning, etc.) and in the subsequent warm-up with a cooling water temperature TW For example, from 60 ° C, depending on the current cooling water temperature, raised to a desired level. In other words, the load point shift is limited as a function of the cooling water temperature.

auf, wobei die Begrenzung der Lastpunktverschiebung erkannt wird, sofern das Drehmoment VKM größer ist als ein Betrag einer Differenz zwischen der Fahrerlast FL und dem Lademoment LM.A method according to the invention has a torque for diagnosing the limitation of the load point shift when the internal combustion engine is warming up VKM the internal combustion engine, a driver load FL of a driver operating the hybrid vehicle and a charging moment LM according to the following relationship $$\text{VKM}>\left|\text{FL}-\text{LM}\right|$$

on, whereby the limitation of the load point shift is recognized, provided that the torque VKM is larger than an amount of a difference between the driver load FL and the loading moment LM .

In a further development of the method according to the invention, there is a so-called offset value Off provided, which takes torque fluctuations into account in a certain order of magnitude. The offset value Off In the present exemplary embodiment, it preferably has an amount of 10 Nm, but is in particular to be adapted to a maximum load and / or power of the internal combustion engine.

Zur Fehlerdiagnose wird des Weiteren eine Mindestzeit herangezogen, welche einen Wert von 2 Sekunden aufweist. Das heißt mit anderen Worten, dass das Drehmoment VKM zur Aktivierung einer Fehlermeldung über einem Zeitintervall von mindestens 2 Sekunden dauerhaft größer sein muss als der Betrag der Differenz zwischen der aktuellen Fahrerlast FL und dem Lademoment zuzüglich des Offsets. Dabei kann bspw. ein über das Zeitintervall gemittelter Wert des Drehmomentes VKM herangezogen werden.With this offset value Off the above-mentioned relationship is formed as follows: $$\text{VKM}>\left|\text{FL}-\text{LM}\right|+\text{Off}$$

A minimum time, which has a value of 2 seconds, is also used for error diagnosis. In other words, that means the torque VKM To activate an error message, it must be permanently greater than the amount of the difference between the current driver load over a period of at least 2 seconds FL and the loading moment plus the offset. For example, a value of the torque averaged over the time interval can be used VKM can be used.

• - eine Kühlmitteltemperatur unterhalb eines Schwellwertes von bspw. 60°C, oder
• - eine Öltemperatur unterhalb eines Schwellwertes von bspw. 60°C, oder
• - eine Katalysatortemperatur unterhalb eines Schwellwertes von bspw. 400°C, oder
• - ein Kriterienblock, welcher eine Bündelung mechanischer Kriterien vorsieht.

Additional criteria for influencing the error message can be added to the proposed diagnostic method to limit the load point shift during warm-up. An additional criterion can be

• - a coolant temperature below a threshold value of, for example, 60 ° C, or
• - an oil temperature below a threshold value of, for example, 60 ° C, or
• - A catalyst temperature below a threshold value of, for example, 400 ° C, or
• - A criteria block, which provides a bundling of mechanical criteria.

• - einem aktuellen Betriebsstatus der Verbrennungskraftmaschine und des Elektromotors, und
• - Betriebsstatus der Kupplung, und
• - Betriebsstatus elektronischer Fahrunterstützungen wie bspw. Antischlupfregelung, elektronisches Stabilitätsprogramm,
• - Betriebsstatus des Getriebes, und
• - Priorisierungsfaktoren zum Betrieb der Antriebseinrichtung.

The criteria block is composed, for example, of

• - A current operating status of the internal combustion engine and the electric motor, and
• - operating status of the clutch, and
• - Operating status of electronic driving support such as anti-slip control, electronic stability program,
• - Operating status of the transmission, and
• - Prioritization factors for the operation of the drive device.

In the 2 to 4th are moment lines in principle moment-time diagrams VKM , FL , LM the internal combustion engine, a driver load and the charging torque in an operating range of the drive device with a permissible load point shift 1 and with impermissible load point shift 2 in operation with a positive driver load, in operation without a driver load and in operation with a negative driver load.

In the example of the positive driver load FL according to 2 indicates in the operating range of the drive device with a permissible load point shift 1 the internal combustion engine generates a torque, which is a torque expenditure a plus a torque requirement b the driver load FL corresponds to. After deducting the torque requirement b the torque expenditure remains a , which a loading moment LM with a loading effort c corresponds to. A shift in the load point is thus possible. However, if the internal combustion engine has a torque VKM which is greater than the sum of the torque required a and the torque requirement b an excess of torque d , the drive device is in an operating range with an impermissible load point shift 2 operated.

Provided there is no driver load FL is present, thus when there is a need for torque b with a value of zero as exemplified in 3rd shown, points in the operating range of the drive device with a permissible load point shift 1 the internal combustion engine generates a torque, which is a torque expenditure a corresponds to the torque requirement a a loading moment LM with a loading effort c corresponds to. A shift in the load point is thus possible. However, if the internal combustion engine has a torque VKM on which is excess torque d is greater than the torque required a , the drive device is in an operating range with an impermissible load point shift 2 operated.

In the example of a negative driver load FL according to 4th indicates in the operating range of the drive device with a permissible load point shift 1 the internal combustion engine generates a torque, which is a torque expenditure a in the amount of the loading cost c corresponds to. A shift in the load point is thus possible. However, if the internal combustion engine has a torque VKM on which is the excess torque d is greater than the sum of the loading costs c minus the torque requirement b , the drive device is in an operating range with an impermissible load point shift 2 operated.

With the help of the diagrams it is easy to see under which conditions the drive device is in an operating range with a permissible load point shift 1 or in an operating range with impermissible load point shift 2 is located.

Provided that the drive device is operated in the operating range of the impermissible load point shift 2 is recognized, an error message regarding the load point shift can be activated. This error message can be in the form of a digital log, or it can be output audibly and / or visibly for the driver, with a voice message or a control lamp preferably being activated.

List of reference symbols

1

permissible load point shift

2

impermissible load point shift

M.

moment

FL

Driver load

LM

Loading moment

Off

Offset value

TK

Coolant temperature cold start

TW

Coolant temperature warm-up

VKM

Internal combustion engine torque

a

Torque expenditure

b

Torque requirement

c

Loading effort

d

Excess torque

t

time

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102013224677 A1 [0003]

Claims (7)

A method for operating a drive device of a hybrid vehicle, wherein the drive device comprises an internal combustion engine and an electric motor, and wherein the hybrid vehicle has auxiliary consumers that can be energized, and wherein a load point shift of the internal combustion engine can be carried out in a warm-up mode of the drive device, the load point shift being limited, and wherein the Limitation of the load point shift is determined with the help of a torque (ICE) of the internal combustion engine, a driver load (FL) of a driver operating the hybrid vehicle and a charging torque (LM) of the electric motor, with an amount of a difference between the driver load (FL) and the charging torque (LM ) is determined, and if the torque (ICE) is greater than the amount of the difference between the driver load (FL) and the loading torque (LM), an operation of the drive device in an area with an impermissible load point shift (2) is detected earth. Procedure according to Claim 1 , characterized in that an offset value (Off) is added to the amount of the difference between the driver load (FL) and the loading torque (LM). Procedure according to Claim 1 or 2 , characterized in that the torques (VKM, LM, FM) are measured over a time interval to determine the torque (VKM). Procedure according to Claim 3 , characterized in that the time interval is at least 2 seconds. Method according to one of the preceding claims, characterized in that further criteria are used to determine the limitation of the load point shift. Method according to one of the preceding claims, characterized in that an error message is activated when the drive device is operated in the operating range with an impermissible load point shift (2). Method according to one of the preceding claims, characterized in that the error message is output audibly and / or visibly.

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