Method for Starting an Internal Combustion Engine of a Motor Vehicle, and Motor Vehicle Comprising an Internal Combustion Engine

Abstract

A method for starting an internal combustion engine and a motor vehicle are provided. The internal combustion engine includes a plurality of cylinders. To start the internal combustion engine while deactivated, a predefined amount of working gas is introduced into the cylinder that fires first. A crankshaft of the internal combustion engine is driven by an electric motor and by the movement of a piston coupled to the crankshaft and associated with the cylinder that fires first to introduce the predefined amount of working gas. Subsequently, the internal combustion engine is started by the ignition of a mixture including the predefined amount of working gas and a predefined amount of fuel inside the cylinder that fires first.

Claims

1-10. (canceled)

11. A method for starting an internal combustion engine of a motor vehicle comprising a plurality of cylinders, comprising: introducing, with the internal combustion engine deactivated, a predetermined quantity of working gas into a cylinder that is fired first of the plurality of cylinders when starting the internal combustion engine, wherein a crankshaft of the internal combustion engine is driven by an electric motor; moving a piston, which is coupled to the crankshaft and is assigned to the cylinder that is fired first, to introduce the predetermined quantity of working gas; and starting the internal combustion engine via ignition of a mixture comprising the predetermined quantity of working gas and a predetermined quantity of fuel within the cylinder that is fired first.

12. The method according to claim 11, wherein the predetermined quantity of working gas is introduced during an engine rundown of the internal combustion engine.

13. The method according to claim 11, wherein the crankshaft is driven by the electric motor at a rotational speed less than an idle rotational speed of the internal combustion engine.

14. The method according to claim 11, wherein valve strokes of respective gas exchange valves, which are assigned to the cylinder that is fired first when starting the internal combustion engine, are set using a valve control device to introduce the working gas into the cylinder that is fired first.

15. The method according to claim 14, wherein the valve stroke of an inlet valve of the respective gas exchange valves is set in order to introduce the working gas into the cylinder that is fired first.

16. The method according to claim 14, wherein the valve stroke of an outlet valve of the respective gas exchange valves is set to introduce the working gas into the cylinder that is fired first.

17. The method according to claim 11, wherein the crankshaft is coupled to a drive wheel of the motor vehicle in a torque-transmitting manner while the crankshaft is driven by the electric motor.

18. The method according to claim 11, further comprising: accelerating the crankshaft is accelerated from a standstill by the electric motor; and after the predetermined quantity of working gas has been introduced into the cylinder that is fired first, setting the crankshaft into the standstill again.

19. The method according to claim 18, wherein the crankshaft is rotated from the standstill by the electric motor in a direction that is oriented opposite to an operating direction of rotation of the crankshaft with the internal combustion engine activated.

20. A motor vehicle comprising: an internal combustion engine comprising a plurality of cylinders; and an electronic control device configured to: control an electric motor to drive a crankshaft of the internal combustion engine when deactivated, move a piston that is coupled to the crankshaft and is assigned to the cylinder that is fired first to start the deactivated internal combustion engine, introduce a predetermined quantity of working gas into the cylinder that is fired first when starting the internal combustion engine, and control a starter of the internal combustion engine such that the starting of the internal combustion engine occurs via an ignition of a mixture within the cylinder that is fired first, wherein the mixture comprises the predetermined quantity of working gas and a predetermined quantity of fuel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 shows a schematic illustration of a motor vehicle having an internal combustion engine and having an electric motor using which a crankshaft of the internal combustion engine can be driven in order to introduce a predetermined quantity of working gas into a cylinder of the internal combustion engine that is fired first when starting the internal combustion engine; and

[0021] FIG. 2 shows a diagram which shows qualitatively different rotational speed profiles of the crankshaft during different starting operations of the internal combustion engine.

[0022] FIG. 1 is a schematic illustration showing a motor vehicle 1 having an internal combustion engine 2.

DETAILED DESCRIPTION OF THE DRAWINGS

[0023] The internal combustion engine 2 comprises a plurality of cylinders, of which in the present case only one cylinder 4 is shown. In the variant shown in FIG. 1, the cylinder 4 corresponds to a so-called starting cylinder which is fired first when starting the internal combustion engine 2. Accordingly, the cylinder 4 can also be referred to as a starting cylinder. In a cylinder interior of the cylinder 4 there is arranged a piston 7 which is assigned to the cylinder 4 and which, together with the cylinder 4, delimits a combustion chamber 22. The piston 7 is coupled to a crankshaft 5 of the internal combustion engine 2 via a connecting rod 23. The crankshaft 5 can be coupled via a clutch (not shown further here) of the motor vehicle 1 to a transmission (likewise not shown further) of the motor vehicle 1. The transmission is coupled to drive wheels (not shown further here) of the motor vehicle 1.

[0024] Working gas 3 can be introduced into the combustion chamber 22 and residual gas in the form of exhaust gas can be discharged from the combustion chamber 22 via respective gas exchange valves 11, 12 which can be assigned to the cylinder 4. Working gas 3 in the form of air can flow into the combustion chamber 22 via the gas exchange valve 11 formed as an inlet valve, insofar as the gas exchange valve 11 is in an open position. Via the gas exchange valve 12 which is formed as an outlet valve, the residual gas can flow out of the combustion chamber 22 and be supplied to exhaust-gas after-treatment systems (not shown further here) of the internal combustion engine 2, which can include, for example, a catalytic converter and a particulate filter.

[0025] The gas exchange valves 11, 12 can be actuated via respective camshafts which are coupled to the crankshaft 5. Thus, one of these camshafts can be formed as an inlet camshaft 24 for actuating the gas exchange valve 11 configured as an inlet valve. Another of these camshafts can be formed as an outlet camshaft 25 for actuating the gas exchange valve 12 configured as an outlet valve.

[0026] The gas exchange valves 11, 12 can also be actuated via a valve control device 13. The valve control device 13 serves to set the valve strokes of the respective gas exchange valves 11, 12, which are assigned to the cylinder 4 which is fired first when starting the internal combustion engine, in order to introduce the working gas 3 into the cylinder 4 which is fired first.

[0027] For this purpose, the valve control device 13 comprises an inlet valve controller 20 and an outlet valve controller 21. Using the inlet valve controller 20, the valve stroke of the inlet valve (gas exchange valve 11) can be set additionally or alternatively to the inlet camshaft 24 in order to introduce the working gas 3 into the cylinder 4. Using the outlet valve controller 21, the valve stroke of the gas exchange valve 12 (outlet valve) can be set additionally or alternatively to the outlet camshaft 25, in order to introduce the working gas 3 into the cylinder 4. Opening both the inlet valve (gas exchange valve 11) and the outlet valve (gas exchange valve 12) allows scavenging of the combustion chamber 22 to be effected, with the result that the predetermined quantity of working gas 3 can be introduced into the cylinder 4, and thus into the combustion chamber 22, with reduction of a flow resistance.

[0028] The motor vehicle 1 is in the present case configured as a hybrid vehicle and comprises an electric motor 6 which is coupled to the crankshaft 5. The electric motor 6 can, for example, take the form of a motor generator, with the result that both a motor mode and a generator mode of the electric motor 6 are possible. Just like the drive wheels, the crankshaft 5 can be driven using the electric motor 6.

[0029] To control the electric motor 6, the motor vehicle 1 comprises an electronic control device 16 which is designed to control the electric motor 6 in such a way that the electric motor 6 drives the crankshaft 5 of the deactivated internal combustion engine 2 and thereby moves the piston 7, which is coupled to the crankshaft 5 and assigned to the cylinder 4 which is fired first. As a result, for subsequent starting of the deactivated internal combustion engine 2, a predetermined quantity of the working gas 3 is introduced into the cylinder 4 which is fired first when starting the internal combustion engine 2. The predetermined quantity of the working gas 3 is in the present case introduced into the combustion chamber 22 during an engine rundown of the internal combustion engine 2.

[0030] The electronic control device 16 is designed to control a starter 17 of the internal combustion engine 2 in such a way that the starting of the internal combustion engine 2 occurs in that, using the starter 17, an ignition of a mixture 8, which is formed in the combustion chamber 22 and comprises the predetermined quantity of working gas 3 and a predetermined quantity of fuel 9, is effected within the cylinder 4 which is fired first.

[0031] The starter 17 comprises in the present case an injector 18 and an igniter 19. Using the injector 18, the predetermined quantity of fuel 9 can, for example, be directly introduced into the combustion chamber 22. For this purpose, the injector 18 can comprise an injector. Using the igniter 19, the mixture 8 can be ignited and, as a result, the internal combustion engine 2 can be activated in that, on account of the ignition of the mixture 8, the crankshaft 5 is rotated in an operating direction of rotation 15 illustrated by an arrow. Subsequent intermittent firing of the cylinders of the internal combustion engine 2 causes the crankshaft 5 to be accelerated further until, for example, the idle rotational speed of the internal combustion engine 2 has been reached.

[0032] The crankshaft 5 can be driven using the electric motor at a rotational speed 10 which is less than an idle rotational speed of the internal combustion engine 2. Alternatively, the crankshaft 5 can also be accelerated from its standstill using the electric motor 6 and, after the predetermined quantity of working gas 3 has been introduced into the cylinder 4 which is fired first, can be set into standstill again. Furthermore, the crankshaft 5 can be rotated from its standstill using the electric motor in a direction 14 which is oriented opposite to the operating direction of rotation 15 of the crankshaft 5 with the internal combustion engine 2 activated.

[0033] Moreover, the crankshaft 5 can be coupled to the drive wheels of the motor vehicle 1 in a torque-transmitting manner while the crankshaft 5 is driven by the electric motor 6. The piston 7 can be moved in a defined manner by the crankshaft 5 being driven using the electric motor 6, and in addition the scavenging of the combustion chamber 22 with the working gas 3 can be effected by opening the gas exchange valves 11, 12. This can ensure that, during subsequent starting of the internal combustion engine 2, little residual gas is contained in the combustion chamber 22 and a defined quantity of fresh air is available for starting the internal combustion engine 2 by igniting the mixture 8.

[0034] FIG. 2 shows a diagram on whose ordinate axis a rotational speed n is plotted and whose abscissa axis a time t is plotted. The diagram shows qualitatively different rotational speed profiles 26, 27, 28, 29 of the crankshaft 5 which can result when starting the internal combustion engine 2. It can be seen in FIG. 2 that the rotational speed profiles 26, 27 are situated tightly together and have a very similar profile, this indicating good reproducibility of respective starting operations of the internal combustion engine 2 on which the rotational speed profiles 26, 27 are based. In order to achieve the rotational speed profiles 26, 27, the predetermined quantity of working gas 3 has been introduced, with the internal combustion engine 2 deactivated, into the cylinder 4 which is fired first when starting the internal combustion engine 2. By contrast thereto, the further rotational speed profiles 28, 29 show that poor reproducibility is achieved when the introduction of the predetermined quantity of the working gas 3 into the cylinder 4 ceases. The rotational speed profiles 26, 27 thus result with an optimized filling of the starting cylinder (cylinder 4) with the predetermined quantity of working gas 3, whereas the unfavorable rotational speed profiles 28, 29 result with non-optimized filling of the cylinder 4.

LIST OF REFERENCE SIGNS

[0035] 1 Motor vehicle [0036] 2 Internal combustion engine [0037] 3 Working gas [0038] 4 Cylinder [0039] 5 Crankshaft [0040] 6 Electric motor [0041] 7 Piston [0042] 8 Mixture [0043] 9 Quantity of fuel [0044] 10 Rotational speed [0045] 11 Gas exchange valve [0046] 12 Gas exchange valve [0047] 13 Valve control device [0048] 14 Direction [0049] 15 Operating direction of rotation [0050] 16 Electronic control device [0051] 17 Starter [0052] 18 Injector [0053] 19 Igniter [0054] 20 Inlet valve controller [0055] 21 Outlet valve controller [0056] 22 Combustion chamber [0057] 23 Connecting rod [0058] 24 Inlet camshaft [0059] 25 Outlet camshaft [0060] 26 Rotational speed profile [0061] 27 Rotational speed profile [0062] 28 Rotational speed profile [0063] 29 Rotational speed profile [0064] n Rotational speed [0065] t Time