DE102013000548B3 - A drive system for a motor vehicle and method for operating a drive system for a motor vehicle - Google Patents

Abstract

The invention relates to a method for a drive system for a motor vehicle (10), comprising an electric motor (12) and an internal combustion engine (14) for driving the motor vehicle (10); a control member (18) having a first kickdown position (30) and adapted to control a respective drive power of the electric motor (12) and the internal combustion engine (14); at least one electrical operating mode in which the drive power can be provided exclusively by the electric motor (12); wherein in the first kickdown position (30) in the electrical operating mode of the drive system, only the maximum deliverable power of the electric motor (12) can be called up; the control element (18) additionally has a second kickdown position (32); in the second kickdown position (32), the maximum deliverable power of the electric motor (12) and of the internal combustion engine (14) can be called independently of the set operating mode. The invention also relates to a method for operating a drive system for a motor vehicle (10).

Description

The invention relates to a drive system for a motor vehicle specified in the preamble of claim 1. Art. Furthermore, the invention relates to a method for operating a drive system for a motor vehicle.

A generic drive system for a motor vehicle is from the US 2012/0053767 A1 known. The drive system comprises an electric motor and an internal combustion engine for driving the motor vehicle, a control element, which has a first kick-down position and is designed to control a respective drive power of the electric motor and the internal combustion engine, at least one electrical operating mode, in which the drive power exclusively by the electric motor is available.

The DE 101 49 905 B4 shows a control system for a hybrid electric vehicle. The control system is configured to proactively determine a power requirement for driving the vehicle and to estimate based on when the presumed retrieved power demand exceeds the maximum deliverable power by the electric motor.

The DE 10 2010 060 839 A1 also includes a hybrid vehicle control system configured to determine when to prematurely turn on an internal combustion engine to achieve required acceleration, as this would not be feasible based solely on the deliverable electrical power of the hybrid vehicle.

The DE 10 2010 018 753 A1 shows a method for operating a motor vehicle, which comprises an electric motor and an internal combustion engine for driving the motor vehicle. The motor vehicle comprises an accelerator pedal acted upon by a restoring force. Within the adjustment range of the accelerator pedal there is a force stage with an increased restoring force. As long as the accelerator pedal is not spent on the power level with the increased restoring force addition, the car is driven purely electrically. As soon as the accelerator pedal is moved beyond the power stage with the increased restoring force, an internal combustion engine for driving the motor vehicle is activated in addition to the electric drive.

The EP 1 297 987 A1 shows a method for controlling an internal combustion engine of a motor vehicle. An accelerator pedal acted upon by a restoring force has two break points along its displacement path. At the break points, the restoring force exerted on the gas pedal increases sharply. When the respective break points are exceeded, the internal combustion engine is operated in respectively different modes.

The DE 10 2011 101 676 A1 shows a method of operating a catalyst heating system of a hybrid vehicle. An electrically heatable catalyst of a catalyst arrangement is heated when the internal combustion engine is switched off. Once the electrically heated catalyst has reached a predetermined temperature, a crankshaft of the internal combustion engine is driven, wherein further no combustion takes place in the internal combustion engine. By driving the crankshaft, air is pumped into the catalyst assembly, whereby another, not electrically heatable catalyst of the catalyst assembly is heated convectively.

The DE 10 2009 049 497 A1 shows a method of operating a hybrid vehicle. Depending on an accelerator pedal position, an electric motor and / or an internal combustion engine are used to drive the hybrid vehicle. By means of an actuator, respective opposing forces can be exerted on the gas pedal for different accelerator pedal positions in order to signal respective pressure points to a driver of the vehicle.

The DE 10 2007 011 739 A1 shows a method of operating a hybrid vehicle. Depending on an accelerator pedal position, an electric motor and / or an internal combustion engine are used to drive the hybrid vehicle. Within an adjustment range of an accelerator pedal, a force level with an increased restoring force is present. As long as the accelerator pedal is not spent on the power level with the increased restoring force addition, the car is driven purely electrically. As soon as the accelerator pedal is moved beyond the power stage with the increased restoring force, an internal combustion engine for driving the motor vehicle is activated in addition to the electric drive.

It is the object of the present invention to provide a drive system of the type mentioned above and a method for operating a drive system for a motor vehicle, by means of which the emissions of the drive system can be reduced.

This object is achieved by a drive system having the features of patent claim 1 and by a method for operating a drive system having the features of patent claim 7. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the dependent claims.

The drive system according to the invention for a motor vehicle comprises an electric motor and an internal combustion engine for driving the motor vehicle, a control element having a first kick-down position and adapted to control a respective drive power of the electric motor and the internal combustion engine, and at least one electric operating mode in which the drive power is provided exclusively by the electric motor. The drive system according to the invention is characterized in that in the first kick-down position in the electrical operating mode of the drive system, only the maximum deliverable power of the electric motor is retrievable; the control element additionally has a second kick-down position; and in the second kick-down position, the maximum deliverable power of the electric motor and the internal combustion engine is independent of the set operating mode available.

In the drive system according to the invention, it is thus provided to provide a second kick-down position of the control element, which may be, for example, an accelerator pedal or the like. In the case of an accelerator pedal this can be depressed, for example, in the first kick-down position and depressed when exceeding this first kick-down position over this away to the second kick-down position. This double kick-down function makes it possible to better dose the power to be retrieved from the drive system and thus the motor vehicle. If the control system is merely brought into the first kick-down position, it is provided that if the drive system is operated in a purely electrical mode, only the maximum power that can be supplied by the electric motor is retrieved only.

In other words, there is no change of the currently set operating mode, in particular, if this operating mode is a purely electrical operating mode. The fact that in this first kick-down position of the internal combustion engine is not additionally switched on or turned on, high emissions can be avoided. This would be particularly critical in such situations when the engine was off for a long time and cooled and thus a corresponding catalyst has cooled. If the internal combustion engine were switched on directly in such a situation and the maximum power that could be provided by it was called up, particularly high emissions would result.

However, if a driver of the motor vehicle is in a particular dangerous situation which requires that the motor vehicle be accelerated as much as possible in order to escape this dangerous situation, it is possible for the driver to move into the second kick-down position regardless of the current operating mode of the motor vehicle or of the drive system, the internal combustion engine is switched on substantially immediately and its maximum power is called up, while at the same time the maximum deliverable power of the electric motor is also retrieved in parallel. Upon actuation of the second kick-down position, it is thus provided in the drive system according to the invention that all available or providable power of the entire drive system is provided substantially directly, in which case, of course, especially during a cold start of the engine and its Exhaust after-treatment system can cause increased emissions.

The drive system according to the invention has the overall advantage that no separate operating mode for realizing a type of hazard scenario function of the drive system, ie the immediate accessibility of the maximum deliverable power of both the internal combustion engine and the electric motor, must be provided. In this respect, no preventive preheating of an exhaust aftertreatment system, such as a catalyst during the pure electrical operation of the drive system is necessary, so that the energy required for this can be saved. The second kick-down position is thus provided according to the invention only for special hazards and corresponds in its logic to a driver actively prompted change of the operating mode in such an operating mode in which the maximum power of both the engine and the electric motor are retrieved or provided can.

Furthermore, it is provided according to the invention that the drive system comprises a control device which is designed to determine the probability and the probable time of activation of the internal combustion engine, taking into account variables influencing the movement of the motor vehicle. An activation of the internal combustion engine is understood to mean that a fired operation of the internal combustion engine is brought about, usually by a corresponding actuation of a starting device. The control device can be designed to determine a kind of predictive engine cold start window in the edge zones of the maximum electrical acceleration and / or the maximum electrical speed. By means of the control device, therefore, a possible driver's request can be predicted and the internal combustion engine can be subjected to a cold start procedure before the driver even requests the additional engine power of the internal combustion engine in which to perform this sequence can, the internal combustion engine would also have to be switched on. Possible variables influencing the movement of the motor vehicle are, for example, the traveled path of the control element, for example a pedal travel, an acceleration of the control element, for example a pedal acceleration, the speed of the motor vehicle, the acceleration of the motor vehicle, geographical profiles from route planning and the like.

Furthermore, it is provided according to the invention that the control device is designed to activate a tempering device for tempering an exhaust gas aftertreatment device for after-treatment of exhaust gases of the internal combustion engine when a predefinable threshold value for the probability of activation of the internal combustion engine is exceeded. For example, the exhaust aftertreatment device may be a 3-way catalyst, a selective catalytic reduction catalyst (short, SCR catalyst) in the context of urea injection, and the like. In other words, the control device is designed to switch on a tempering device, for example in the form of a heater or the like, so that it can preheat an exhaust aftertreatment device such that, as soon as the internal combustion engine is actually switched on, it has reached a corresponding operating temperature, so that the exhaust aftertreatment device can effectively reduce the emissions of the internal combustion engine, in particular within the framework of the statutory emissions regulations.

In particular, it is provided in a further advantageous embodiment of the invention that the control device is designed to turn on the temperature control with such a time lead, that the exhaust aftertreatment device is temperature-controlled before activating the internal combustion engine to a predetermined operating temperature. As a result, a particularly effective emission reduction can be achieved.

In an advantageous embodiment of the invention, it is provided that the first kick-down position and the second kick-down position, a respective resistor is assigned, which for the movement of the control element in the first or in the second kick-down position overcome. This allows a driver to be provided in a simple manner by the respective characteristic resistances for the kick-down positions, a specific feedback, so that the driver can clearly determine whether he is the control element just in the first kick-down position or the second kick Down position.

In a further advantageous embodiment of the invention, it is provided that the second resistor is greater than the first resistor. In other words, it is thus provided that a lesser expenditure of force is required to move the control element into the first kick-down position than to move the control element into the second kick-down position into which the control element is preferably also first moved can be when the control element is moved beyond the first kick-down position. The second resistor is preferably set so large that a driver must consciously and very strongly act on the control element in order to spend this at all in the second kick-down position. This avoids accidental actuation of the control element in the second kick-down position.

• – Überprüfen, ob sich ein Steuerungselement zum Steuern einer jeweiligen Antriebsleistung eines Elektromotors und eines Verbrennungsmotors in einer ersten oder einer zweiten Kick-Down-Stellung befindet;
• – falls sich das Steuerungselement in der ersten Kick-Down-Stellung befindet: Überprüfen, ob das Antriebssystem in einem rein elektrischen Betriebsmodus betrieben wird und falls dies der Fall ist, ausschließlich Abrufen der mittels des Elektromotors maximal bereitstellbaren Leistung;
• – falls sich das Steuerungselement in der zweiten Kick-Down-Stellung befindet: Abrufen der maximal bereitstellbaren Leistung des Elektromotors und des Verbrennungsmotors unabhängig von dem eingestellten Betriebsmotors des Antriebssystems.

The method according to the invention for operating a drive system for a motor vehicle comprises the following steps:

• - Checking whether a control element for controlling a respective drive power of an electric motor and an internal combustion engine is in a first or a second kick-down position;
• - if the control element is in the first kick-down position: check whether the drive system is operated in a purely electrical operating mode and, if so, exclusively retrieving the maximum power that can be supplied by the electric motor;
• - If the control element is in the second kick-down position: retrieving the maximum deliverable power of the electric motor and the internal combustion engine regardless of the set operating motor of the drive system.

Furthermore, by means of a control device of the drive system taking into account variables influencing the movement of the motor vehicle, the probability and the probable point in time of activating the internal combustion engine are determined, wherein a tempering device for controlling the temperature is exceeded if a predefinable threshold value for the probability of activation of the internal combustion engine by means of the control device an exhaust aftertreatment device is activated for the aftertreatment of exhaust gases of the internal combustion engine.

Advantageous embodiments of the drive system are to be regarded as an advantageous embodiment of the method according to the invention.

Further advantages, features and details of the invention will become apparent from the the following description of a preferred embodiment and with reference to the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the combination indicated, but also in other combinations or in isolation, without the frame to leave the invention.

Embodiments of the invention are explained in more detail below with reference to schematic drawings. Show it:

1 a schematic representation of a motor vehicle with a drive comprising an electric motor and an internal combustion engine and a control element for controlling a respective drive power of the electric motor and the internal combustion engine; and in

2 a schematic representation of an accelerator pedal designed as a control element for controlling the drive power of the internal combustion engine and the electric motor, wherein the dashed line or the dash-dotted line a first kick-down position or a second kick-down position of the accelerator pedal are shown.

A car 10 is in a schematic representation in 1 shown. The car 10 has an unspecified drive system, which is an electric motor 12 , an internal combustion engine 14 , a control device 16 and a control element designed as an accelerator pedal 18 for controlling the respective drive powers of the electric motor 12 and the internal combustion engine 14 includes. Furthermore, the motor vehicle includes 10 a catalyst 20 for exhaust aftertreatment of the internal combustion engine 14 , With the catalyst 20 it may be, for example, a 3-way catalyst. Furthermore, it is also possible to provide further exhaust aftertreatment devices, not shown here, such as, for example, catalysts for reducing nitrogen oxide emissions in connection with a urea injection and the like.

In the present case, the drive system or the motor vehicle 10 designed such that serving as a drive axle front axle 22 and thus also corresponding front wheels 24 optionally from the electric motor 12 , the internal combustion engine 14 or through both sources of power 12 . 14 can be driven. Alternatively, it is also possible that the drive system is designed such that the electric motor 12 and the internal combustion engine 14 for driving a rear axle unspecified here and thus for driving respective rear wheels 26 is trained. Furthermore, the drive system can also be designed such that by means of the electric motor 12 and the internal combustion engine 14 both the front wheels 14 as well as the rear wheels 26 are driven, so an all-wheel drive is provided.

The drive system of the motor vehicle 10 includes, inter alia, a purely electrical mode of operation, in which the drive power exclusively by the electric motor 12 is available. The drive system may also include a variety of other modes of operation, such as a SOC _min mode in which the drive system of the motor vehicle is operated such that the battery state of charge of the electric motor 12 battery still contains sufficient residual energy to drive in a next driving cycle 500 meters electric to 35 km / h.

Furthermore, the drive system may include a basic emission management mode. Under a basic mode is to be understood a selectable mode in which the limit value compliance must be detected in the exhaust cycle. The characteristics and behavior of the motor vehicle 10 are designed so that without further intervention of the driver according to predetermined statutory limits are exceeded.

As another basic mode, a so-called power mode (or performance mode) may be provided, which starting at the speed 0 km / h, ie from the state of the motor vehicle 10 out, the maximum system performance, so the maximum deliverable power by the electric motor 12 and the internal combustion engine 14 provides. The internal combustion engine 14 It starts conventionally at the beginning of the driving cycle, with a start-stop operation or in other words a start-stop system is possible. In order to comply with required emission standards, the necessary emission reduction measures will be implemented. The power mode can also be understood as escape or danger mode, since during the power mode the maximum by means of the electric motor 12 and the internal combustion engine 14 Provable power can be provided.

In the already mentioned electrical operating mode or basic mode, only the electrical power is made available as system power, whereby possibly following a target driving curve, for example in the form of desired accelerations and / or speeds, is not always possible. After reaching a minimum predetermined state of charge of the battery, the operating mode is automatically changed and the internal combustion engine 14 started.

Further, another basic mode, a so-called battery-saving mode is possible in which the car 10 purely the power of the internal combustion engine 14 as a system performance provides. However, boosting and recuperation may be possible as part of a hybrid strategy. The internal combustion engine 14 starts in this mode even at a speed of 0 km / h, ie from the state of the motor vehicle 10 out. Optionally, an electric starting is possible.

As another basic mode may be provided a battery charging mode in which the battery is charged from the Rekuperationsenergie and by means of a load point shift, wherein the total retrieved energy pure from the engine 14 available power does not exceed.

In addition, other basic modes, such as economy, dynamic or auto are possible, in which the system performance of the drive system or the motor vehicle 10 by a mixed operation of the electric motor 12 and the internal combustion engine 14 is available. In this case, appropriate specifications can be made, so that, for example, the car 10 is purely electric in motion and the engine is only started when, for example, over 90% of the electrically achievable maximum speed has been reached or, for example, over 90% of the electrical power has been requested for more than a predetermined period of time. To effectively reduce emissions in real-world driving, the driver only has mode-specific engine power available after a warm-up period that significantly reduces emissions.

The gas pedal 18 serves, as already explained, to the respective drive power of the electric motor 12 and the internal combustion engine 14 depending on the respective selected mode of the drive system. In 2 is the gas pedal 18 shown in different positions. With the solid line 28 is a starting position of the accelerator pedal 18 shown in which no power from both the electric motor 12 as well as the internal combustion engine 14 is retrieved. With the dashed line 30 is a first kick-down position of the accelerator pedal 18 represented and by the dotted line 32 is a second kick-down position of the accelerator pedal 18 shown.

The drive system of the motor vehicle 10 is designed such that in the first kick-down position 30 in the purely electrical operating mode of the drive system, only the maximum deliverable power of the electric motor 12 is available. In the second kick-down position 32 on the other hand, both the maximum deliverable power of the electric motor 12 as well as the internal combustion engine 14 essentially immediately accessible regardless of the operating mode set.

Should a driver drive the car 10 So operate, for example, in the purely electrical mode of operation, in which it is also only provided exclusively that the retrieved drive power only by the electric motor 12 is provided, the driver can quasi electric boost the accelerator pedal 18 in the first kick-down position 30 spend, which then instantly the maximum deliverable power of the electric motor 12 provided.

Should the driver be in an exceptional emergency situation in which it should be necessary to drive the car 10 accelerate as much as possible to avoid this dangerous situation, the driver can accelerate 18 about the first kick-down position 30 out to the second kick-down position 32 move. As soon as the gas pedal 18 into the second kick-down position 32 has been spent, is substantially instantaneously both the maximum deliverable power of the electric motor 12 as well as the internal combustion engine 14 regardless of the set operating mode. In other words, in the case described, an instantaneous change of the operating mode from the purely electrical operating mode to the power mode, in which both the electric motor 12 as well as the internal combustion engine 14 immediately the maximum power can be provided.

The gas pedal 18 is designed such that the first kick-down position 30 and the second kick-down position 32 a respective resistor, not shown here, is assigned, which is used to move the gas pedal 18 in the first or second kick-down position 30 . 32 to overcome. In this case, the second resistor is preferably set larger by some than the first resistor. In other words, the first resistance must first be overcome at all, to the accelerator pedal 18 in the first kick-down position 30 being able to spend, being, the gas pedal 18 additionally also in the second kick-down position 32 can only be spent when a correspondingly larger second resistance has been overcome. This can avoid the second kick-down position 32 unintentionally set by a driver.

The respective resistors can also serve to send a corresponding signal to the control device 16 forward, if the gas pedal 18 into the respective kick-down position 30 respectively. 32 has been spent. Alternatively or additionally, however, it is also possible, in particular in the case of an e-gas, for the respective kick-down positions to be present 30 . 32 detected by the e-gas and the control device 16 to be provided.

The control device 16 is designed to take into account the movement of the motor vehicle 10 influencing variables, the probability and the probable time of activation of the internal combustion engine 14 to investigate. For this, the control device 16 via sensors, not shown here, a wide variety of information about the movement of the motor vehicle 10 , for example in the form of the current speed of the motor vehicle 10 whose acceleration and the like are provided. In addition, it is additionally possible, by means of a position detection, the respective position or acceleration of the accelerator pedal 18 to capture and forward to the controller.

Furthermore, for example, route information, topography information and the like, for example, from a navigation system of the control device, not shown here 16 to be provided. Taking into account all or only some of these variables, the control device 16 predict a possible driver's request, for example, that the driver equal acceleration of the motor vehicle 10 wish, which due to various boundary conditions not from the electric motor 12 alone can be made possible. The control device 16 is designed to exceed a predetermined threshold for the probability of activation of the internal combustion engine 14 to activate a tempering and in particular to turn them on with such a time delay that the catalyst 20 before activating the internal combustion engine 14 is temperature controlled to a predetermined operating temperature. The others, possibly in the car 10 provided exhaust aftertreatment devices may also include other temperature control devices not shown here, which can then be switched on in time.

This is used in particular to the emissions of the internal combustion engine in real driving outside of any test cycles 14 effectively reduce. Specifically, in the edge zones of the maximum possible purely electrical acceleration and / or maximum achievable purely electrically speed, a predictive engine cold start window is formulated. The prognosis of the driver's request serves to the internal combustion engine 14 and also the catalyst 20 subject to a corresponding cold start procedure, before the driver, the additional power of the engine 14 is required.

It can be additionally provided that during or after the movement of the accelerator pedal 18 into the second kick-down position 32 a cold start procedure is then also suppressed or stored, if the second kick-down position 32 Connected driver's request, regardless of the current operating state to retrieve the maximum system performance, from the controller 16 should have been predicted. This can help to maximize system performance by directly connecting the internal combustion engine 14 can be done even faster. In addition, the electric energy otherwise expended for preheating an exhaust gas aftertreatment device may optionally be used to drive the electric motor 12 be used, so that the maximum propulsive power can be increased again.

In this context, it is also possible that predetermined electrical consumers, when reaching or recognizing the second kick-down position 32 at least temporarily deactivated or no longer be supplied with electrical energy, this energy for supplying the electric motor 12 is used so that a further increased propulsion power can be provided. The given consumers are preferably consumers providing comfort functions, such as an air conditioning compressor, a rear window heater and the like. As soon as the gas pedal 18 no longer in the second kick-down position 32 is spent, these electrical loads are supplied with electrical energy or reactivated.

Claims (5)

Drive system for a motor vehicle ( 10 ), with - an electric motor ( 12 ) and an internal combustion engine ( 14 ) for driving the motor vehicle ( 10 ); A control element ( 18 ), which has a first accelerator pedal position ( 30 ) and for controlling a respective drive power of the electric motor ( 12 ) and the internal combustion engine ( 14 ) is designed; At least one electrical operating mode, in which the drive power is produced exclusively by the electric motor ( 12 ) is available; characterized in that - in the first accelerator pedal position ( 30 ) in the electrical operating mode of the drive system, only the maximum deliverable power of the electric motor ( 12 ) is retrievable; The control element ( 18 ) additionally a second accelerator pedal position ( 32 ) having; In the second accelerator pedal position ( 32 ) the maximum deliverable power of the electric motor ( 12 ) and the internal combustion engine ( 14 ) is retrievable regardless of the set operating mode; The drive system is a control device ( 16 ), which is designed to, under Consideration of the movement of the motor vehicle ( 10 ) influencing variables the probability and the probable time of activation of the internal combustion engine ( 14 ) to investigate; - the control device ( 16 ) is designed, when exceeding a predefinable threshold value for the probability of activation of the internal combustion engine, a tempering device for controlling the temperature of an exhaust gas aftertreatment device ( 20 ) for the aftertreatment of exhaust gases of the internal combustion engine ( 14 ) to activate. Drive system according to claim 1, characterized in that the first accelerator pedal position ( 30 ) and the second accelerator pedal position ( 32 ) is associated with a respective resistor which is used to move the control element ( 18 ) in the first and second accelerator pedal position ( 30 . 32 ) is to be overcome. Drive system according to claim 2, characterized in that the second resistor is greater than the first resistor. Drive system according to one of the preceding claims, characterized in that the control device ( 16 ) is designed to turn on the tempering device with such a time advance that the exhaust gas aftertreatment device ( 20 ) is temperature-controlled before activating the internal combustion engine to a predeterminable operating temperature. Method for operating a drive system for a motor vehicle ( 10 ), with the steps: - Checking whether a control element ( 18 ) for controlling a respective drive power of an electric motor ( 12 ) and an internal combustion engine ( 14 ) in a first or a second accelerator pedal position ( 30 . 32 ) is located; - if the control element ( 18 ) in the first accelerator pedal position ( 30 Check that the propulsion system is operating in a purely electrical mode of operation and, if so, exclusive retrieval by means of the electric motor ( 12 ) maximum deliverable power; - if the control element ( 18 ) in the second accelerator pedal position ( 32 ): Retrieving the maximum deliverable power of the electric motor ( 12 ) and the internal combustion engine ( 14 ) regardless of the set operating mode of the drive system; - wherein by means of a control device ( 16 ) of the drive system taking into account the movement of the motor vehicle ( 10 ) influencing variables the probability and the probable time of activation of the internal combustion engine ( 14 ) is determined; In which, when a predefinable threshold value for the probability of activation of the internal combustion engine is exceeded ( 14 ) by means of the control device ( 16 ) a tempering device for tempering an exhaust aftertreatment device ( 20 ) for the aftertreatment of exhaust gases of the internal combustion engine ( 14 ) is activated.

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