DE102019003725A1 - Method for operating a motor vehicle, in particular a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a motor vehicle which has an externally ignited internal combustion engine with a crankshaft and at least one exhaust gas turbocharger, by means of which the internal combustion engine can be supplied with compressed air, in which an input caused by the driver of the motor vehicle and requesting a racing start of the motor vehicle is recorded and the start of the race is carried out as a function of the detection of the input.

Description

The invention relates to a method for operating a motor vehicle, in particular a motor vehicle.

The DE 10 2010 024 589 A1 discloses a drive train for a motor vehicle, with a drive unit which can be connected via a first transmission element to a rotor of an electrical machine that can be operated as a generator and / or an electric motor. Furthermore, the DE 10 2005 026 066 A1 a method for limiting a torque provided by an internal combustion engine of a motor vehicle can be found as known.

The object of the present invention is to create a method for operating a motor vehicle, so that a particularly strong acceleration of the motor vehicle can be achieved.

This object is achieved by a method with the features of claim 1. Advantageous refinements with expedient developments of the invention are specified in the remaining claims.

In the method according to the invention for operating a motor vehicle preferably designed as a motor vehicle, in particular as a passenger car, the motor vehicle comprises an externally ignited internal combustion engine, for example designed as a gasoline engine, which has an output shaft in the form of a crankshaft and a throttle valve. Via the crankshaft, the internal combustion engine can provide torques for driving and in particular for starting the motor vehicle, which is initially stationary, for example. The motor vehicle also includes at least one exhaust gas turbocharger, by means of which the internal combustion engine can be supplied with compressed air.

In a first step of the method, an input made by the driver of the motor vehicle and requesting a race start of the motor vehicle is recorded. In other words, the input is a request also referred to as a race start request or a race start request, since the driver requests the aforementioned race start or its implementation by effecting the input. In other words, through the input, the driver expresses his wish that the motor vehicle, which is initially stationary, for example, starts the race and accelerates it forward particularly strongly, i.e. with a particularly high acceleration, and is thus started up during the start of the race. By starting the race or by executing the start of the race, the motor vehicle is operated, in particular regulated, in such a way that the motor vehicle is accelerated forwards with a particularly high acceleration, in particular with the highest possible acceleration, and is started, in particular while the driver is in the interior of the motor vehicle and also called accelerator pedal fully depressed with his foot and thus holds in an end position or end position.

In a second step of the method, also designated with a), the throttle valve is opened to increase the air mass flow or the engine load as a function of the acquisition of the input or as a result of the acquisition of the input. In a third step of the method, also designated by b), an ignition of the internal combustion engine is retarded as a function of the detection of the input. This means that a respective fuel-air mixture in a respective combustion chamber of the internal combustion engine is ignited by external ignition at a later point in time or at a later rotational position of the crankshaft than before the ignition was delayed. In a fourth step of the method, also referred to as c), a bypass valve, also referred to as a bypass, bypass valve, wastegate or wastegate valve, is closed, whereby a bypass line via which exhaust gas from the internal combustion engine is to be bypassed from a turbine of the exhaust gas turbocharger is closed . In a fifth step of the method, also denoted by d), an electric machine of the motor vehicle is operated in a generator mode, in which the electric machine is driven by the internal combustion engine via the crankshaft, provides electrical energy or electrical current for charging a battery of the motor vehicle and thereby the maximum torque, also known as charging torque, for charging the battery from the crankshaft. The second step (step a)), the third step (step b)), the fourth step (step c)) and the fifth step (step d)) during a standstill of the motor vehicle and in particular while the motor vehicle is by means of, for example designed as a service brake braking device of the motor vehicle is braked and thereby held at a standstill. The first, second, third, fourth and fifth steps can take place in parallel or sequentially.

In a sixth step of the method, the driver's wish to start off is determined. The sixth step is preferably carried out after the first step. The driver's wish to start off is determined, for example, in such a way that it is determined or recognized that the driver is in the interior of the motor vehicle arranged and designed to actuate the aforementioned braking device releases the brake pedal and / or reduces a force exerted on the brake pedal. The start-up request is a wish of the driver to carry out the race start and thus to accelerate the initially stationary motor vehicle with a particularly high acceleration, that is to say particularly strongly, through the race start, in particular while the driver fully depresses the accelerator pedal.

In a seventh step of the method, an engagement process is started, by means of which an initially opened clutch, via which the crankshaft can be coupled to the wheels of the motor vehicle, is closed. In an eighth step of the method, the throttle valve is opened to the maximum with the maximum setting of the air mass flow or preload of the exhaust gas turbocharger within the limits of an existing drive slip control. In a ninth step of the method, the ignition is again adjusted for optimum efficiency or advanced according to the engine knock protection. In a tenth step of the method, the generator braking power is shed, wherein the seventh, eighth, ninth and tenth steps can take place in parallel or sequentially. In an eleventh step of the method, the braking power is released in the form of propulsive power. In a twelfth step of the method, the electric machine is operated in an engine mode in which the electric machine supports the crankshaft in driving the wheels and thus the motor vehicle and thereby in a race start, i.e. in the execution of the race start, in which the initially stationary motor vehicle is started and is strongly accelerated.

The seventh, eighth, ninth, tenth, eleventh and twelfth steps are carried out as a function of the determination of the start-up request or as a result of the determination of the start-up request.

With the method according to the invention and in particular with the fifth step, a particularly high speed and / or a particularly high boost pressure of the exhaust gas turbocharger can be set while the motor vehicle is at a standstill and thus before the motor vehicle actually starts, so that the motor vehicle is particularly strong or particularly high when the race starts can be accelerated quickly. In this way, extreme acceleration can be carried out, by means of which the motor vehicle is accelerated particularly strongly, that is to say with a particularly high acceleration.

Because the electrical machine is driven by the crankshaft and thus by the internal combustion engine, the internal combustion engine receives a torque loss in the form of the torque also referred to as charging torque. It is preferably provided that, for example in the fifth step and thus during the standstill of the motor vehicle, also referred to as the stationary phase, additional torque losses are applied to the crankshaft and thus to the internal combustion engine. For example, in the fifth step, an air conditioning system or an air conditioning compressor of an air conditioning system of the motor vehicle is driven by the internal combustion engine in order to thereby build up a particularly high boost pressure in an intake system. The boost pressure is a pressure at which the air is compressed by means of the exhaust gas turbocharger. At the start of the coupling process, the torque loss or torques are then thrown off, so that at least almost all of the boost pressure and thus at least almost all of the drive torque provided by the internal combustion engine via its crankshaft is available to drive and thus accelerate the motor vehicle. The method according to the invention thus enables a significantly faster build-up of boost pressure and drive torque compared to conventional methods, with the drive torque that is provided by the internal combustion engine via the crankshaft in order to drive the motor vehicle, also referred to as engine torque.

For example, the internal combustion engine, also referred to as an internal combustion engine or motor, is turned up to a predeterminable speed of, for example, 4,000 revolutions per minute and maintained during standstill, in particular when the driver has made the input and fully depresses the accelerator pedal and keeps it fully depressed, in particular in such a way that that the internal combustion engine is regulated to said speed. For example, the speed is regulated by cylinder suppression and / or throttle valve intervention. In this case, an attempt is usually made at the same time to increase the internal load of the internal combustion engine by deliberately worsening the efficiency of the internal combustion engine by means of retarded ignition in comparison to an earlier ignition. Retarded ignition means that the ignition is delayed. This results in a particularly high exhaust gas mass flow that drives the turbine and a particularly high exhaust gas temperature, which means that the exhaust gas turbocharger is pretensioned in such a way that the maximum drive torque is reached as quickly as possible at the start of the coupling process, i.e. when the clutch is engaged to start up, thanks to a particularly rapid run-up of the exhaust gas turbocharger will can. Compared to conventional methods, an improvement is achieved in that the highest possible load is applied to the crankshaft during standstill. This creates a boost pressure that is significantly higher than with conventional methods. The exhaust gas mass flow and, at the same time, the exhaust gas temperature also increase via the turbine.

A starter generator, in particular a belt starter generator (RSG) or an integrated starter generator (ISG), is preferably used as the electrical machine. The belt starter generator is characterized, for example, in that the electrical machine has a stator and a rotor which can be driven by the stator and can thus be rotated about a machine axis of rotation relative to the stator. For example, the machine axis of rotation runs parallel to an engine axis of rotation about which the crankshaft can be rotated relative to a crankcase of the internal combustion engine. The motor axis of rotation and the machine axis of rotation are thus spaced apart from one another and run parallel to one another, for example. In contrast to this, for example the integrated starter generator or its rotor is arranged coaxially to the crankshaft and, for example, on the crankshaft.

During the standstill and during the fifth step, the maximum torque, also referred to as the maximum charging torque, is called up for charging the battery, as a result of which the battery is charged by means of the generator during the fifth step. As soon as the coupling process, also referred to as the coupling process, begins, the charging torque is thrown off, so that suddenly a particularly high torque is available for starting the motor vehicle. This torque available for starting the motor vehicle is significantly higher in the method according to the invention than in conventional methods.

Ideally, the electric machine is operated, for example, during and / or after the coupling process or during and / or after its start in the support mode, also known as boost mode, and thus in its motor mode, whereby the wheels and thus the motor vehicle are operated by means of the internal combustion engine and by means of the electric machine are driven. In the motor mode, the electric machine functions as an electric motor, by means of which the wheels and thus the motor vehicle are driven in addition to the internal combustion engine. Since the battery is or has been charged beforehand during the standstill, a particularly large amount of electrical energy stored in the battery is available for the start of the race, which can be used to operate the electrical machine in the engine mode.

Further advantages, features and details of the invention emerge from the following description of a preferred exemplary embodiment and with reference to 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 single figure can be used not only in the specified combination, but also in other combinations or on their own, without the frame to leave the invention.

In the single figure, the drawing shows a flowchart to illustrate a method according to the invention.

A method for operating a motor vehicle, preferably designed as a motor vehicle, in particular as a passenger vehicle, is illustrated below with reference to the figure. The motor vehicle has an externally ignited internal combustion engine, which is also referred to as an engine or internal combustion engine and is designed, for example, as an Otto engine. The internal combustion engine has an output shaft in the form of a crankshaft, via which the internal combustion engine can provide torques for driving the motor vehicle. The respective torque for driving the motor vehicle is also referred to as the engine torque or drive torque or drive torque or engine torque. In particular, wheels of the motor vehicle and thus the motor vehicle itself can be driven by means of the drive torque, whereby, for example, the motor vehicle, which is initially stationary, can be started up and thus set in motion as part of a start-up process.

The motor vehicle also has at least one exhaust gas turbocharger, by means of which the internal combustion engine can be supplied with compressed air. For this purpose, the exhaust gas turbocharger has a turbine and a compressor that can be driven by the turbine. The turbine is arranged in an exhaust tract of the internal combustion engine, the exhaust tract of which can be traversed by exhaust gas from the internal combustion engine. The compressor is arranged in an intake system through which air can flow. The air flowing through the intake system can be compressed by means of the compressor. The turbine can be driven by the exhaust gas from the internal combustion engine flowing through the exhaust system. Since the compressor can be driven by the turbine, the energy contained in the exhaust gas can be used to compress the air.

The turbine is assigned a bypass device which has a bypass line. The bypass line is connected to the exhaust gas tract at a branch point and an inlet point, the branch point being arranged upstream of the turbine. The discharge point is arranged downstream of the turbine. At the branch point, part of the exhaust gas flowing through the exhaust tract can first be branched off from the exhaust tract and introduced into the bypass line. The exhaust gas branched off at the branch point from the exhaust tract and introduced into the bypass line flows through the bypass line and bypasses the turbine, so that the turbine is not driven by the exhaust gas flowing through the bypass line. Thus, the turbine can be bypassed via the bypass line of at least part of the exhaust gas flowing through the exhaust gas. At the introduction point, the exhaust gas flowing through the bypass line can flow out of the bypass line and flow back into the exhaust gas tract.

The bypass device also includes a bypass valve, which is also referred to as a bypass, bypass valve, wastegate or wastegate valve. The bypass valve can be used to set an amount of exhaust gas flowing through the bypass line. The bypass valve can be adjusted between at least one closed position and at least one open position. In the closed position, the bypass valve closes at least part of a flow cross-section of the bypass line through which the exhaust gas can flow, the bypass valve releasing the part in the open position. In particular, it can be provided that the bypass valve completely fluidically blocks the flow cross-section or the bypass line in the closed position, so that no more exhaust gas can flow through the bypass line, possibly with the exception of technically-related and unavoidable leakages. If the bypass valve is moved from the open position into the closed position, the bypass valve is closed. In other words, adjusting the bypass valve from the open position into the closed position is also referred to as closing the bypass valve. In addition, the internal combustion engine comprises at least one throttle valve, by means of which an amount of air to be supplied to at least one combustion chamber of the internal combustion engine can be or is adjusted.

With a first step S1 of the method, an input caused by the driver of the motor vehicle and requesting a race start of the motor vehicle is recorded or recognized. The start of the race is a start-up process, the motor vehicle being accelerated particularly strongly by the start of the race or by the start of the race. When the race is started, for example - while the driver fully depresses an accelerator pedal located in the interior - is operated, in particular regulated, in such a way that the motor vehicle is accelerated with a particularly high acceleration, in particular with the highest possible acceleration.

In a second step S2 During the process, the throttle valve is opened to increase the air mass flow or the engine load. For this purpose, for example, partial opening and / or regulation of the throttle valve takes place. In a third step S3 of the method, an ignition of the internal combustion engine is delayed. In a fourth step S4 the bypass valve is closed during the process. On a fifth step S5 According to the method, an electrical machine of the motor vehicle is operated in a generator mode and thus as a generator. In generator mode, the electric machine is driven by the internal combustion engine via the crankshaft, with the electric machine in generator mode providing electrical energy for charging a battery of the motor vehicle and the maximum torque provided or possible for charging the battery, also known as the charging torque, of the crankshaft. Thereby the steps S2 , S3 , S4 and S5 carried out as a function of the detection of the input and while the motor vehicle is at a standstill, which stands still during the standstill. For example, in the fifth step S5 a braking power via a generator torque through a maximum set battery charging current, by means of which the battery is charged, in particular maximally.

On a sixth step S7 During the process, a start-up request by the driver is determined. At least the steps S2 , S3 , S4 and S5 are carried out while the motor vehicle is being braked by means of a braking device of the motor vehicle, for example designed as a service brake, and is thereby held at a standstill. The driver's wish to start off is determined or recognized, for example, in such a way that it is detected that the driver ends an actuation of the braking device or reduces it in such a way that the actuation of the braking device effected by the driver is below a limit value.

On a seventh step S6 of the method, a coupling process is started by which an initially opened clutch, via which the crankshaft can be coupled to the wheels of the motor vehicle, is closed. Thus, for example, the clutch is at least during the steps S2 , S3 , S4 , S5 and S7 open. Especially a maximum idle load is set - while the clutch, also known as the starting clutch, is open - since, for example, the motor vehicle is at a standstill. At an eighth step S8 of the method, a maximum opening of the throttle valve with maximum setting of the air mass flow or preloading of the exhaust gas turbocharger is carried out within the limits of an existing drive slip control. At a ninth step S9 During the process, the ignition is again adjusted for optimum efficiency or advanced according to the engine knock protection. At a tenth step S10 of the method there is a shedding of the generator braking power, and in an eleventh step S11-1 During the process, the braking power is released in the form of propulsive power. Specifically, lies at the eleventh step S11-1 a maximum starting power generated by the internal combustion engine on or before. At a twelfth step S11-2 In the process, the electric machine is operated in a motor mode and thus as an electric motor. When the engine is running, the electric machine assists the crankshaft when driving the wheels and thereby when starting a race or when starting a race, so that the motor vehicle is accelerated particularly strongly when the race starts and is thus started. Specifically, lies at the twelfth step S11-2 an additional power generated by an electric motor for starting up or before. In addition, 10 denotes a control circuit for setting an increased starting speed with a maximum pre-tensioned static load.

The method can ensure a particularly high exhaust gas temperature and thus a particularly high speed and a particularly high boost pressure of the exhaust gas turbocharger so that the internal combustion engine can provide a particularly high drive torque via the crankshaft at the start of the race. As a result, the motor vehicle can be accelerated strongly or quickly by the start of the race.

List of reference symbols

10

Control loop

S1

first step

S2

second step

S3

Third step

S4

fourth step

S5

fifth step

S6

seventh step

S7

sixth step

S8

eighth step

S9

ninth step

S10

tenth step

S11-1

eleventh step

S11-2

twelfth step

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 102010024589 A1 [0002]
• DE 102005026066 A1 [0002]

Claims (4)

Method for operating a motor vehicle which has an externally ignited internal combustion engine with a crankshaft and a throttle valve and at least one exhaust gas turbocharger, by means of which the internal combustion engine can be supplied with compressed air, with the following steps: I. Acquisition of an input caused by the driver of the motor vehicle and requesting a start of a race of the motor vehicle (step S1); II. Depending on the recording of the input: a) opening the throttle valve to increase the air mass flow or the engine load (step S2); b) adjusting an ignition of the internal combustion engine to retard (step S3); c) closing a bypass valve, whereby a bypass line, via which a turbine of the exhaust gas turbocharger is to bypass exhaust gas from the internal combustion engine, is closed (step S4); d) Operating an electrical machine in a generator mode, in which the electrical machine is driven by the internal combustion engine via the crankshaft, provides electrical energy for charging a battery and absorbs the maximum torque for charging the battery from the crankshaft (step S5), the Steps a), b), c) and d) are carried out while the motor vehicle is stationary, in a control loop with constant engine speed, steps I., a), b), c) and d) being carried out in parallel or sequentially ; III. Determining a start-up request by the driver (step S7); IV. Depending on the determination of the start-up request: e) starting a coupling process, by means of which an initially opened clutch, via which the crankshaft can be coupled to the wheels of the motor vehicle, is closed (step S6); f) maximum opening of the throttle valve with maximum setting of the air mass flow or preloading of the exhaust gas turbocharger within the limits of an existing drive slip control (step S8); g) Adjusting the ignition for optimum efficiency or according to the engine knock protection early (step S9); h) dropping off the generator braking power (step S10), steps e), f), g) and h) being carried out in parallel or sequentially; i) releasing the braking power in the form of propulsive power (step S11-1); and j) Operating the electrical machine in an engine mode, in which the electrical machine assists the crankshaft in driving the wheels and thereby in the start of the race, in which the initially stationary motor vehicle is started (step S11-2). Procedure according to Claim 1 , characterized in that an integrated starter generator or a belt starter generator is used as the electrical machine. Procedure according to Claim 1 or 2 , characterized in that steps a), b) and c) are carried out while the motor vehicle is braked by means of a braking device of the motor vehicle and is thereby kept at a standstill. Method according to one of the preceding claims, wherein the maximum engine idle load is set in stoichiometric operation.

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