DE102016009324A1 - Method for starting an internal combustion engine of a motor vehicle - Google Patents

Abstract

The invention relates to a method for starting an internal combustion engine of a motor vehicle, in which the internal combustion engine is started (step S2) to terminate a sailing operation (step S1) of the internal combustion engine, wherein the internal combustion engine is started by means of a starting operation in which the internal combustion engine by means of a in addition to the internal combustion engine provided starter motor and by towing is started by a clutch is closed, thereby coupling an output shaft of the internal combustion engine with at least one wheel of the motor vehicle, wherein the starting operation comprises: - a first period during which the output shaft driven by the starter motor is applied by the starter motor acting in a first direction of rotation of the output shaft torque on the output shaft; and - a second period subsequent to the first time period during which the clutch is or is closed and an applied by the starter motor applying a acting in a direction opposite to the first direction of rotation second rotational direction torque on the crankshaft is omitted.

Description

The invention relates to a method for starting an internal combustion engine of a motor vehicle according to the preamble of patent claim 1.

Such a method for starting an internal combustion engine of a motor vehicle, for example, is already the WO 2015/161848 A1 to be known as known. In the method, the internal combustion engine is started to end a sailing operation of the internal combustion engine. In other words, the internal combustion engine is started, for example during a transition from the sailing operation in a different operating state of the internal combustion engine from the sailing operation.

In the method, the internal combustion engine is started by means of a starting operation in which the internal combustion engine is started by means of a starter motor in addition to the internal combustion engine and by towing by a clutch is closed, thereby coupling an output shaft of the internal combustion engine with at least one wheel of the motor vehicle. The starter motor is usually referred to as a starter or starter and is for example an electric motor, by means of which a torque is applied to the output shaft of the internal combustion engine for starting the internal combustion engine. As a result, the output shaft is driven by means of the starter motor to thereby start the internal combustion engine. Under the towing the internal combustion engine is to be understood that in the context of towing the clutch is closed, thereby to couple the output shaft of the internal combustion engine with at least one wheel of the motor vehicle. As a result, the output shaft is driven by the wheel via the closed clutch, whereby the internal combustion engine is started, that is started by towing.

During the sailing operation, the clutch is opened, so that the output shaft is decoupled from the wheel, in particular from all wheels of the motor vehicle. Furthermore, the internal combustion engine is deactivated during the sailing operation, that is, switched off. In addition, during the sailing operation, the motor vehicle rolls over its wheels along a roadway and thereby on the roadway, whereby the internal combustion engine or its output shaft is not driven by the wheels via the clutch because the clutch is open during the sailing operation. By closing the clutch, the output shaft is coupled to at least one of the wheels, whereby the internal combustion engine or the output shaft is towed or pulled up so that then the internal combustion engine can be started. By starting the internal combustion engine, a fired operation of the internal combustion engine is set so that combustion processes take place in at least one combustion chamber, for example designed as a cylinder, of the internal combustion engine. As a result of these combustion processes, the internal combustion engine or its output shaft is driven so that the internal combustion engine can then provide torques for driving the motor vehicle or the at least one wheel via its output shaft.

Furthermore, the DE 10 2013 221 479 A1 a method for controlling a clutch start after a motor-stop sailing phase of a motor vehicle, the service brake is actuated and the brake system can be influenced by a clutch control with respect to the braking torque. In this case, it is provided that the braking torque is reduced by the value of a braking-acting clutch torque that causes the clutch start by closing the clutch as an effective wheel torque. Finally, out of the DE 10 2013 225 150 A1 a method for starting an internal combustion engine of a motor vehicle is known.

Object of the present invention is to develop a method of the type mentioned in such a way that the internal combustion engine can be started particularly advantageous.

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

In order to develop a method specified in the preamble of claim 1 type such that the internal combustion engine can be started particularly advantageous, it is inventively provided that the starting process includes a first period during which the output shaft is driven by the starter motor by the starter motor In a first direction of rotation of the output shaft acting torque is applied to the output shaft. This torque is hereinafter referred to as positive torque, which is applied by means of the starter motor to the output shaft, thereby to rotate or drive the output shaft in the first direction of rotation. During the first time period, the clutch may be open, for example, so that the output shaft is not covered by wheels of the Motor vehicle, which rolls over its wheels along a road and thereby rolls on the road, is driven or can be driven.

According to the invention, the starting process comprises a second period of time, preferably immediately or directly following the first time period during which the clutch is or is closed. Further, during the second period of time, an application of a torque acting in a direction of rotation opposite to the first rotational direction by the starter motor does not occur on the crankshaft. This means that during the second period by means of the starter motor no torque is applied to the output shaft, which acts in the opposite direction of rotation of the first second direction. By closing the clutch or by the fact that the clutch is closed, the output shaft of at least one of the wheels of the motor vehicle is driven in the first direction of rotation, in which the output shaft is driven during the first period by means of the starter motor, that is rotated. During the second period, no torque is applied by means of the starter motor to the output shaft, which counteracts the driving of the output shaft caused by the closing of the clutch. It can be provided that during the second period by means of the starter motor formed on the crankshaft, for example output shaft acting in the first direction of rotation torque or no torque is applied, wherein it may be provided that the example designed as an electric motor starter motor is deactivated during the second period is.

Preferably, the second time period directly or directly adjoins the first time period. As further advantageous, it has been shown that the first period of time is particularly short, wherein the first time period is, for example, less than one second.

Characterized in that the output shaft is rotated in the first rotational direction during the first period by means of the starter motor and in that the output shaft is also rotated by the closing of the clutch in the first direction of rotation, the towing of the internal combustion engine is supported by the starter motor. Furthermore, the starter motor does not oppose towing during the second period of time because the starter motor does not apply torque to the output shaft that acts in the second direction of rotation. A torque which acts in the second direction of rotation and is applied to the crankshaft counteracts the positive torque described above and is therefore also referred to as a negative torque. According to the invention, it is provided that during the second time period no negative torque is applied by means of the starter motor to the crankshaft, so that the starter motor does not oppose the towing. As a result, a particularly advantageous and in particular effective and efficient starting operation of the internal combustion engine can be realized.

In a particularly advantageous embodiment of the invention, a decision process is provided, in the context of which it is decided whether the previously described support of the towing by the starter motor, which is also referred to as a starter or starter, is even necessary. This means that it is preferably provided that the starting operation is carried out as a function of a mass and / or a speed of the motor vehicle. It has been found to be particularly advantageous if, depending on the mass and / or the speed of the motor vehicle, a second starting operation is performed, in which the internal combustion engine is started by closing the clutch and caused by the starter motor starting the internal combustion engine. Thus, it is preferably provided that in the second starting operation, the carrying out of the first startup operation is omitted. These embodiments are based on the finding that, in a motor vehicle with a high mass, the energy available for towing the internal combustion engine and designed, for example, as kinetic energy of the motor vehicle is so large and, in particular, sufficiently large that towing can be carried out without problems or without support from the starter motor can be carried out.

However, if the mass or the speed of the motor vehicle is so low that an excessive deceleration and thus loss of comfort could thus occur due to the low kinetic energy of the motor vehicle, then the first starting process is carried out, in which the towing of the internal combustion engine is carried out supported by the starter motor. It has been shown that in motor vehicles with low mass or at low speed by the existing low kinetic energy towing at the beginning can lead to a noticeable deceleration of the motor vehicle, which is described by the support of towing, that is by the use of the starter motor , can be avoided. In order to realize a particularly advantageous and in particular comfortable start of the internal combustion engine even in vehicles with low weight, the first starting process as Combined engine start provided in the context of the towing the internal combustion engine is supported by means of the starter motor. As a result, excessive delays and thus excessive loss of comfort can be avoided.

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

The drawing shows in the single FIGURE a flowchart illustrating a method for starting an internal combustion engine of a motor vehicle, in which the internal combustion engine is started by means of a start operation to end a sailing operation of the internal combustion engine, wherein the starting operation comprises at least two temporally successive periods.

The single FIGURE shows a flowchart illustrating a method for starting an internal combustion engine of a motor vehicle, which is designed for example as a motor vehicle, especially as a passenger car, and driven by means of the internal combustion engine. The motor vehicle includes wheels, over which the motor vehicle can roll along a roadway and thereby roll on or on the roadway. The internal combustion engine is part of a drive train for driving the motor vehicle. The drive train in this case comprises a clutch which is adjustable between a closed state and an open state. The internal combustion engine comprises at least one combustion chamber designed, for example, as a cylinder and an output shaft designed, for example, as a crankshaft, via which the internal combustion engine, in particular in its fired operation, can provide torques for driving the motor vehicle. In the closed state of the clutch, the output shaft is coupled via the clutch with at least one of the wheels, so that the at least one wheel can be driven via the clutch of the internal combustion engine or so that the output shaft via the clutch of the at least one wheel and thus kinetic energy of the moving and thereby rolling over the wheels along the roadway motor vehicle can be driven. In the open state, the output shaft is decoupled from the wheels, so that the output shaft in the open state of the clutch can not be driven via the clutch from the wheels.

In a first step S1 of the method, the internal combustion engine or the motor vehicle is operated in a sailing mode, which is also referred to as sailing or sailing mode. During the sailing operation, the internal combustion engine is deactivated so that no combustion processes take place in the combustion chamber. Furthermore, the clutch is open during sailing operation. Furthermore, the motor vehicle is in a rolling mode during the sailing operation. This means that during the sailing operation, the motor vehicle rolls over its wheels along the road and thereby rolls on the road. Since the clutch is opened during the sailing operation, the output shaft of the internal combustion engine is not driven by the clutch from the wheels and thus not by the kinetic energy of the motor vehicle.

In a second step S2 of the method, the internal combustion engine, which is also referred to as an internal combustion engine, started to end the sailing operation. By starting the internal combustion engine, it is converted into its fired operation, in which combustion processes take place in the combustion chamber. In the second step S2, the internal combustion engine is started by means of a starting process, which will be explained in more detail in the following. As part of the starting process, the internal combustion engine is started by means of a starter motor provided in addition to the internal combustion engine, wherein the starter motor is also referred to as a starter or starter. The starter motor includes an electric motor by means of which the output shaft is driven to thereby start the internal combustion engine. Further, the internal combustion engine is started in the starting process by towing. The starting of the internal combustion engine by towing takes place such that the clutch is closed, thereby coupling the output shaft of the internal combustion engine with at least one of the wheels of the motor vehicle. By closing the clutch, the output shaft is driven by the at least one wheel, whereby then the internal combustion engine is started.

In order to realize a particularly advantageous start of the internal combustion engine, the starting process comprises a first time period during which the clutch can be opened and the output shaft is driven by means of the starter motor by the starter motor has a positive acting in a first direction of rotation of the output shaft Apply torque to the output shaft. As a result, the output shaft is rotated by means of the starter motor in the first direction of rotation. The process further includes a second time period subsequent to the first time period during which the clutch is or is closed. In this case, the second period of time can directly and immediately follow the first time span or else overlap with the first time span or can be joined later by a third, short time span. By closing or closing the clutch, the output shaft is rotated, for example, in the first direction of rotation, in particular of the at least one wheel. Further, during the second period of time, a negative torque caused by the starter motor is not applied to a second direction of rotation opposite to the first direction of rotation the crankshaft. This means that during the second period by means of the starter motor to the crankshaft no torque is applied, which acts in the second direction of rotation, so that the starter motor does not oppose the towing during the second period. It has been found to be particularly advantageous if the starter motor is deactivated during the second period.

The embodiment of the method is based on the following findings. To start an internal combustion engine, which is also called internal combustion engine, after a sailing operation, which is also referred to as sailing phase, there are basically two options: A first of the possibilities is the towing described by the clutch is closed. The second option is to start the internal combustion engine by means of the conventional starter motor.

In this case, both methods per se have respective disadvantages, which, however, can be solved by means of the method. When the internal combustion engine is started by towing, a deceleration of the motor vehicle occurs essentially as a function of the mass of the motor vehicle and of the speed of the motor vehicle. The smaller the vehicle mass or the driving speed, the greater the deceleration of the vehicle when towing. The delay has the following negative aspects: loss of comfort for occupants of the motor vehicle; Loss of kinetic energy; any impairment of the driving condition of the motor vehicle, especially at low Fahrreibreibwerten; Impairment of a continuous traffic flow, so that it can come by mistake propagation to the emergence of a traffic jam.

Trigger of the deceleration of the motor vehicle are the internal engine friction and the compression of the filling of the combustion chamber. If the combustion chamber is designed as a cylinder, then the filling is also referred to as cylinder filling. For the compression of the cylinder filling a significant proportion of the torque to be applied is payable. The torque for loosening the internal combustion engine or the output shaft is determined by the closing force of the clutch. The higher the closing force, the higher the forces acting on bearings and components. Furthermore, resulting from the necessary high torque, a high start gradient, which can affect both adversely on the life of the components.

Even when starting the internal combustion engine by means of the conventional starter motor for compressing the cylinder charge a certain torque must be provided by the starter motor so long until an injection, that is, introduction of fuel into the combustion chamber begins and the internal combustion engine, the output shaft itself, that is, by means of the combustion processes in the combustion chamber, can rotate. This starting method leads to the following problems: high electrical energy requirement; sometimes long starting time, until the internal combustion engine is running, which can be disturbing especially in opinion change situations; The starting period of the internal combustion engine takes different lengths, which can have a negative effect on drivability. Under a change of mind situation is to understand such a situation in which the internal combustion engine, for example, at least automatically disabled, since at least one corresponding condition is met, but it comes a short time later to circumstances in which at least one parameter leads to the corresponding Condition for the stop of the internal combustion engine is no longer satisfied, so that the internal combustion engine should be restarted automatically. This can be done, for example, the intervention of a driver who enters a driver's request or a driving command, in particular by accelerator pedal, which can lead to changed circumstances and so to a change of mind situation.

In principle, it is possible to circumvent the problems of towing such that restrictions on the mass or speed of the vehicle take place, which ultimately leads to a functional restriction. This means that only in vehicles that are sufficiently loaded or have a high speed, the sailing operation is available. The problem with starting by means of the starter motor can in some ways in automated operation (cruise control) means Foresight be bypassed. For this, however, the internal combustion engine must be started unnecessarily earlier, so that a secured propulsion is available at the desired time. In a change of mind situation, for example in driver interaction, the appropriate sensors, for example a camera, can be used to anticipate driver interaction. However, this is possible only within certain limits, which means that not in all situations the propulsion through the internal combustion engine is available at the desired time.

These problems and disadvantages can be avoided by means of the method, since a combined engine start is carried out in the context of the method. For example, first the starter motor is driven during the first period of time, which lasts less than one second, for example, and immediately thereafter the clutch is closed. The aim of the method is to overcome by means of the starter motor, the engine compression, that is, the compression of the filling in the combustion chamber and then bring the internal combustion engine or the output shaft speedily and reproducibly by means of the closing of the clutch to a desired speed. The method can also be designed so that the clutch is controlled simultaneously with the starter or even shortly before.

The starter motor may for example be designed as a conventional starter. Furthermore, it is conceivable that the starter motor is designed as any other electrical machine that is integrated, for example, in the drive train. In particular, the starter motor may be an electric machine or an electric motor, which is also designed to drive the motor vehicle designed, for example, as a hybrid vehicle. Furthermore, it is conceivable that the starter motor is designed as a starter generator or is part of such a starter generator.

Furthermore, it is conceivable to use the combined engine start only depending on the situation. Here, the trained as a combined engine start starting process, for example, at low mass of the motor vehicle, that is then carried out when the mass of the motor vehicle falls below a predetermined threshold. Alternatively or additionally, the combined engine start is performed when the speed of the vehicle is low, that is, when the speed of the motor vehicle falls below a predefinable threshold. Alternatively or additionally, it is conceivable to carry out the combined engine start in situations that can not be fully automated or predicted.

Overall, by means of the method according to the invention, an improved starting behavior after sailing operation can be represented, since the internal combustion engine can be started quickly, reproducibly and without delay. The method allows the speedy, reproducible and delay-free starting of the internal combustion engine even at low mass of the motor vehicle, at low speed of the motor vehicle, at low Fahrreibreibwerten and / or unpredictable situations.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• WO 2015/161848 A1 [0002]
• DE 102013221479 A1 [0005]
• DE 102013225150 A1 [0005]

Claims (6)

A method for starting an internal combustion engine of a motor vehicle, wherein the internal combustion engine is started (step S2) to end a sailing operation (step S1) of the internal combustion engine, wherein the internal combustion engine is started by means of a starting operation in which the internal combustion engine provided by means of an addition to the internal combustion engine Starter motor and by towing is started by a clutch is closed, thereby to couple an output shaft of the internal combustion engine with at least one wheel of the motor vehicle, characterized in that the starting operation comprises: - a first period during which the output shaft is driven by means of the starter motor in that the starter motor applies a torque acting in a first direction of rotation of the output shaft to the output shaft; and - a second period subsequent to the first time period during which the clutch is or is closed and a torque applied by the starter motor applying a acting in a direction opposite to the first rotational direction second rotational direction torque on the crankshaft is omitted. A method according to claim 1, characterized in that the starter motor is deactivated during the second period. A method according to claim 1 or 2, characterized in that the second period immediately follows the first time period. Method according to one of the preceding claims, characterized in that the starting operation is carried out in dependence on a mass and / or a speed of the motor vehicle. A method according to claim 4, characterized in that, depending on the mass and / or the speed, a second starting operation is performed, in which the internal combustion engine is started by closing the clutch and caused by the starter motor starting the internal combustion engine is omitted. Method according to one of the preceding claims, characterized in that the clutch is closed during the first period.

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