Method for Operating a Motor Vehicle, and Motor Vehicle

Abstract

The present disclosure is directed to operation of a motor vehicle including a first motor configured as an internal combustion engine and a second motor configured as an electric motor. The first motor comprises a combustion chamber, an ignition source and a prechamber that is coupled fluidically to the combustion chamber and into which a portion of the ignition source is introduced. The first motor can be operated by ignition of a fuel/air mixture in the prechamber interior by the ignition source. By way of a control device, the first motor is activated in a manner dependent on a load requirement, and is operated by ignition of the fuel/air mixture in the prechamber interior by the at least one ignition source only when it is operated exclusively in a stable combustion state as a result.

Claims

1-10. (canceled)

11. A method for operating a motor vehicle, comprising: activating a first motor of the motor vehicle by at least one control device depending on a load requirement, wherein the first motor is an internal combustion engine comprising at least one combustion chamber and at least one prechamber with a prechamber interior fluidically coupled to the at least one combustion chamber and into which at least one ignition source is introduced; and operating, by the at least one control device, the first motor such that ignition of a fuel-air mixture in the prechamber interior by the at least one ignition source occurs only when the first motor is operated exclusively in a stable firing state in order to fulfil the load requirement.

12. The method according to claim 11, further comprising: supplying an electrical energy store of the motor vehicle with energy generated during operation of the first motor at least in the stable firing state, at least when a predefined charge state of the electrical energy store is not reached, wherein the electrical energy store is configured to provide electrical energy for a second motor is an electric motor.

13. The method according to claim 11, further comprising: operating the first motor by ignition of fuel by a second ignition source of the first motor protruding directly into the combustion chamber, driving the motor vehicle by the first motor, at least when driving of the motor vehicle by the second motor is excluded and the load requirement indicates that operation of the first motor by ignition of the fuel-air mixture in the prechamber interior by means of the at least one ignition source would lead to the unstable firing state.

14. The method according to claim 11, further comprising: operating the prechamber as a passive prechamber at least in a full-load operation of the first motor.

15. The method according to claim 11, further comprising: operating the prechamber as an active prechamber at least in a part-load operation of the first motor.

16. The method according to claim 11, wherein an unstable firing state is assigned to a low-load range between 0% and maximum 10% of a maximum load of the first motor.

17. A motor vehicle comprising: a first motor configured as an internal combustion engine; a second motor, configured to drive the motor vehicle and configured as an electric motor; and at least one control device configured to control the first motor and the second motor; wherein the first motor comprises: at least one combustion chamber; at least one ignition source; and at least one prechamber which has a prechamber interior fluidically coupled to the at least one combustion chamber, and into which the at least one ignition source is introduced at least in regions, wherein the first motor is operated by ignition of a fuel-air mixture in the prechamber interior by the at least one ignition source in a stable firing state and in an unstable firing state, and wherein the control device is configured to activate the first motor depending on a load requirement and control the first motor to be operated by ignition of the fuel-air mixture in the prechamber interior by the at least one ignition source only when the first motor operates exclusively in the stable firing state in order to fulfil the load requirement.

18. The motor vehicle according to claim 17, further comprising: a serial hybrid drivetrain to which the first motor and the second motor are assigned.

19. The motor vehicle according to claim 17, further comprising: a parallel hybrid drivetrain to which the first motor and the second motor are assigned.

20. The motor vehicle according to claim 17, further comprising: a power-branched hybrid drivetrain to which the first motor and the second motor are assigned.

21. The motor vehicle according to claim 17, further comprising: an electrical energy store configured to: provide electrical energy for the second motor; and be supplied with energy generated on operation of the first motor at least in the stable firing state, at least when a predefined charge state of the electrical energy store is not reached.

22. The motor vehicle according to claim 21, wherein the electrical energy store is a high-voltage battery.

23. The motor vehicle according to claim 17, further comprising: a second ignition source of the first motor protruding directly into the combustion chamber, wherein the first motor is configured to be operated by ignition of fuel by the second ignition source, and wherein the motor vehicle is driven by the first motor, at least when the driving of the motor vehicle by the second motor is excluded and the load requirement indicates that operation of the first motor by ignition of the fuel-air mixture in the prechamber interior by the at least one ignition source would lead to the unstable firing state.

24. The motor vehicle according to claim 17, wherein the prechamber is configured to be operated as a passive prechamber at least in a full-load operation of the first motor.

25. The motor vehicle according to claim 17, wherein the prechamber is operated as an active prechamber at least in a part-load operation of the first motor.

26. The motor vehicle according to claim 17, wherein the unstable firing state is assigned to a low-load range between 0% and maximum 10% of a maximum load of the first motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 shows an abstract illustration of a motor vehicle comprising two equally abstractly shown motors for driving the motor vehicle, wherein a first motor, shown in regions in schematic sectional illustration, of the two motors is configured as an internal combustion engine, and a second motor of the motors as an electric motor, and the first motor has at least one combustion chamber, at least one ignition source and at least one prechamber which has a prechamber interior fluidically coupled to the at least one combustion chamber and in which at least one ignition source is introduced at least in regions in order to ignite a fuel-air mixture in the prechamber interior; and

[0039] FIG. 2 shows a qualitative depiction of a characteristic map, which may also be called a load map, having a low-load range in which the first motor can be operated in an unstable firing state on ignition of the fuel-air mixture in the prechamber interior by means of the at least one ignition source, and which shows a load range different from the low-load range in which the first motor can be operated in a stable firing state on ignition of the fuel-air mixture in the prechamber interior by means of the least one ignition source.

DETAILED DESCRIPTION

[0040] FIG. 1 shows in a schematic illustration a motor vehicle 10 which comprises two motors 20, 50. A first motor 20 of these two motors 20, 50 is here configured as an internal combustion engine. A second motor 50 of the two motors 20, 50 is configured as an electric motor in this case. In the present case, the motor vehicle 10 can be driven with each of the motors 20, 50. In other words, the motors 20, 50 can each generate drive power, in particular independently of one another, and use this power to drive the drive wheels (not shown here) of the motor vehicle 10. The motor vehicle 10 may thereby for example be driven and hence moved purely by the combustion engine and/or purely electrically.

[0041] It is clear that the motor vehicle 10 may also comprise for example several second motors 50, by means of which the motor vehicle 10 can be driven. For example, it is conceivable that a respective second motor 50, which may e.g. be configured as a wheel hub motor, may be assigned to each wheel of an axle of the motor vehicle 10, to name just one example.

[0042] The motors 20, 50 may be actuated, i.e. regulated and operated in controlled fashion, by means of a control device 60 of the motor vehicle 10 which is coupled for signaling purposes to each of the motors 20, 50. The at least one second motor 50 may e.g. be designed as a motor generator. Independently thereof, the motors 20, 50 may be mechanically coupled together, or be able to be mechanically coupled together by a clutch device of the motor vehicle 10 (not shown in the present case). The motor vehicle 10 comprises an energy store 52, which may for example be configured as a high-voltage battery or traction battery. The at least one second motor 50 can be supplied with electrical energy by the energy source 20.

[0043] The motor vehicle 10 may for example comprise a serial hybrid drivetrain or a parallel hybrid drivetrain to which the motors 20, 50 may be assigned. Alternatively, the motor vehicle 10 may comprise a power-branched hybrid drivetrain to which the motors 20, 50 may be assigned. To summarize, various operating strategies of the motors 20, 50 are thus conceivable.

[0044] FIG. 1 also shows, in schematic sectional illustration, an extract of the first motor 20 configured as an internal combustion engine. In this extract, a part region of a cylinder head 12 of the first motor 20 can be seen. An ignition source 24, in the present case designed as a spark plug, is arranged on the cylinder head 12. One end of the ignition source 24 is introduced into a prechamber interior 32 of a prechamber 30 of the first motor 20. Ignition energy, for example in the form of an ignition spark, may be released at this end in order to ignite and thereby burn a fuel-air mixture 34 present in the prechamber interior 32. In the present case, the ignition source 24 and prechamber 30 are connected together via a fixing element 26, which may for example be configured as a locking ring. It is also evident from FIG. 1 that the prechamber 30 comprises several passage openings 36, via which the prechamber interior 32 is fluidically, in particular gas-conductively, connected to a combustion chamber 22 of the first motor 20.

[0045] By ignition of the fuel-air mixture 34 in the prechamber interior 32 by means of the at least one ignition source 24, the first motor 20 may be operated in a stable firing state Z1 and in an unstable firing state Z2. The stable firing state Z1 and the unstable firing state Z2 are assigned to different load ranges 70, 80, namely a low-load range 70 and a load range 80 different from the low-load range 70, which are shown schematically in a characteristic map KF shown in FIG. 2. The stable firing state Z1 is assigned to the load range 80 and the unstable firing state Z2 to the low-load range 70. In this case, an engine load ML is shown on an ordinate of the map KF as a percentage (%) of a full load of the first motor 20, while a rotation speed n, with the unit revolutions per minute, is shown on an abscissa of the map KF. The full load may also be called the maximum load. The full load of the first motor 20 corresponds to a value of 100%. In addition, a minimum rotation speed n.sub.min, which may be called the idle rotation speed of the first motor 20, and a maximum rotation speed n.sub.max of the first motor 20 are shown qualitatively on the abscissa.

[0046] The first motor 20 is activated by the control device 60 depending on a load requirement, and operated by ignition of the fuel-air mixture 34 in the prechamber interior 32 by means of the ignition source 24, only when thereby the first motor 20 can be operated exclusively in the stable firing state Z1 in order to fulfil the load requirement.

[0047] The first motor 20 may be operated in the stable firing state Z1 by the air-fuel mixture 34 being ignited in the prechamber interior 32 by means of the ignition source 34, and as a result of ignition, torch jets enter the combustion chamber 22 via the passage openings 36. The torch jets (not shown) may then ignite fuel present in the combustion chamber 22 and thus burn this, causing the movement of a piston (not shown in detail) which at least partially delimits the combustion chamber 22 of the first motor 20, and hence a crankshaft (also not shown in detail) coupled to the piston of the first motor 20 can be driven.

[0048] The electrical energy store 52, configured to provide electrical energy for the second motor 50 (here a high-voltage battery or traction battery), of the motor vehicle 10 is supplied with energy generated in operation of the first motor 20 in the stable firing state Z1 at least when a predefined charging state of the electrical energy store 52 is not reached. The charging state of the electrical energy store 52 may also be abbreviated to SOC (state of charge).

[0049] The first motor 20 can then be operated by ignition of the fuel by means of a second ignition source 40 protruding directly into the combustion chamber 22 of the first motor 20, and the motor vehicle 10 driven by means of the first motor 20, at least when driving of the motor vehicle 10 by the second motor 50 is excluded and the load requirement suggests that the unstable firing state Z2 would prevail on operation of the first motor 20 by ignition of the fuel-air mixture 34 in the prechamber interior 32 by means of the ignition source 24. The second ignition source 40 in this case is also configured as a spark plug. In other words, during operation of the first motor 20 in the low-load range 70, no ignition of the fuel-air mixture 34 takes place using the ignition source 24 and hence inside the prechamber interior 32, in order to avoid the first motor 20 thereby running in the unstable firing state Z2. Instead, the first motor 20 can be operated in the low-load range 70 by ignition of the fuel directly in the combustion chamber 22 using the second ignition source 40. The second ignition source 40 is shown in highly abstract form in FIG. 1 for reasons of clarity, and there illustrated by a dotted line.

[0050] The prechamber 30 may be operated as a passive prechamber, at least in operation of the first motor 20 at full load, i.e. in other words, in full load operation of the first motor 20. In a part-load operation of the first motor 20, the prechamber 30 may also be operated as an active prechamber. The part-load operation is assigned to a part-load range which extends between the low-load range 70 illustrated in FIG. 2 and full load. The part-load range may thus correspond to a part of the load range 80 excluding full load. It is evident from FIG. 2 that the unstable firing state Z2 extends over the low-load range 70, which in the present case lies for example exclusively between 0% and maximum 10% of maximum load (100% of motor load ML).

[0051] The present method allows the first motor 20 (internal combustion engine) to be operated exclusively in the stable firing state Z1 by so-called prechamber ignition, i.e. by ignition of the fuel-air mixture 34 in the prechamber interior 32 by means of the ignition source 24, wherein by means of the torch jets formed thereby and passing through the passage openings 36 into the combustion chamber 22, the fuel in the combustion chamber 22 is ignited and as a result the piston is moved and the crankshaft driven.

[0052] The method is based on the knowledge that stable ignition and combustion by prechamber ignition cannot be reliably and reproducibly guaranteed at very low loads of the first motor 20, i.e. in other words, on operation of the first motor 20 in the low-load range 70, e.g. at idle, and/or with very retarded ignition angles in the low-load range 70. Furthermore, it is based on the knowledge that the prechamber ignition at high loads, i.e. during operation of the internal combustion engine (first motor 20) in the load range 80 and also at full load, offers significant advantages over internal combustion engines without prechamber, in particular in the combustion sequence.

[0053] The method with this starting point allows targeted operation of the first motor 20 with prechamber ignition in hybrid vehicle drive, i.e. with serial, parallel or power-branched hybrid drivetrain. Operation of the first motor 20 in the low-load range 70 with prechamber ignition in the unstable firing state Z2 can be suppressed, or in other words avoided, in targeted fashion. For example, operation of the first motor 20 in the low-load range 70 may be omitted completely if the charge state of the electrical energy store 52 is sufficient to power the motor vehicle 10 exclusively using the (at least one) second motor 50 and hence purely electrically. If the predefined charging state is not reached, which is the case for example with a discharged (empty) electrical energy store 52, the first motor 20 may for example be accelerated unfired using the second motor 50 or using a starter of the motor vehicle 10, and operated by firing by prechamber ignition directly above the low-load range 70. The first motor 20 can thus effectively be accelerated from a standstill and operated in coasting mode until the stable firing state Z1 is possible with prechamber ignition in the load range 80. Ignition of the fuel-air mixture 34 may then take place directly, in particular exclusively, in the load range 80. Accordingly, the operating point of the first motor 20 may be raised to an operating range outside the low-load range 70, and hence operation of the first motor 20 in the stable firing state Z1 is possible, in order for example to charge the energy store 52 by means of the first motor 20 andadditionally or alternativelyto drive the motor vehicle 10 by means of the first motor 20.

LIST OF REFERENCE SIGNS

[0054] 10 Motor vehicle [0055] 12 Cylinder head [0056] 20 First motor [0057] 22 Combustion chamber [0058] 24 Ignition source [0059] 26 Fixing element [0060] 30 Prechamber [0061] 32 Prechamber interior [0062] 34 Fuel-air mixture [0063] 36 Passage opening [0064] 40 Second ignition source [0065] 50 Second motor [0066] 52 Energy store [0067] 60 Control device [0068] 70 Low-load range [0069] 80 Load range [0070] KF Characteristic map [0071] ML Motor load [0072] n Rotation speed [0073] n.sub.min Minimum rotation speed [0074] n.sub.max Maximum rotation speed [0075] Z1 Stable firing state [0076] Z2 Unstable firing state