Method for operating a drive device and corresponding drive device

Abstract

A method for operating a drive device includes heating a hot air stream with a heating device integrated in a cylinder head of an internal combustion engine of the drive device, wherein the internal combustion engine is connected with an exhaust gas system; mixing the hot air stream upstream of a catalytic converter with a cold fresh air stream for adjusting a defined temperature of the hot air stream; and supplying the hot air stream having the adjusted defined temperature to the catalytic converter in at least one operating state of the internal combustion engine so as to heat the catalytic converter.

Claims

1. A drive device, comprising: an internal combustion engine having a cylinder head with a plurality of cylinders; an exhaust gas system connected to the internal combustion engine and including a catalytic converter; a heating device integrated in the cylinder head and heating a cold air stream to produce a hot air stream which is mixed upstream of the catalytic converter with a chemically unaltered cold fresh air stream for adjusting a defined temperature of the hot air stream to provide the adjusted hot air stream having the adjusted defined temperature and supplied to the catalytic converter in at least one operating state of the internal combustion engine so as to heat the catalytic converter; a conduit conducting the chemically unaltered cold fresh air through at least one of the cylinders which is operated in a trailing throttle mode; an air distributor branching off the cold air stream from a fresh air stream at a retrieval point upstream of the internal combustion engine and conducting the cold air stream to the heating device; a compressor compressing the fresh air stream upstream of the retrieval point; and a connecting line supplying the fresh air stream to the air distributor for providing the cold air stream and the chemically unaltered cold fresh air stream.

2. The drive device of claim 1, wherein the at least one cylinder has at least one inlet valve and at least one outlet valve operating so that the chemically unaltered cold fresh air stream is transported in a direction of the catalytic converter.

3. The drive device of claim 1, wherein the heating device is constructed as a burner operating with liquid or gaseous fuel.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the following, the invention is described by way of the exemplary embodiments shown in the drawing, without limiting the invention. It is shown in the sole FIGURE a schematic representation of the drive device with an internal combustion engine and an exhaust gas system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(2) The FIGURE shows a schematic representation of a drive device 1 with an internal combustion engine 2, which has multiple cylinders 3, and with an exhaust gas system 4. Each cylinder 3 has at least one inlet valve 5 and at least one outlet valve 6. The inlet valves 5 of the cylinders 3 are connected to the air distributor 7, which is preferably constructed as a common air distributor. For this purpose connection lines 8 are provided. The air distributor 7 is fluidly connected to a compressor 10 via a line 9, which compressor can for example be driven by means of an electric motor 11. In addition or as an alternative the compressor 10 can also be a part of a charger, in particular an exhaust gas turbo charger or a blower. On the side facing away from the air distributor 7, the compressor 10 is fluidly connected to an external environment 13 of the drive device 1 via a line 12. By means of the compressor 10 the fresh air can thus be suctioned from the external environment 13 and conducted to the air distributor 7 in the form of a fresh air stream 14. Preferably an air filter is fluidly arranged between the compressor 10 and the external environment 13.

(3) The exhaust gas system 4 has an exhaust manifold 15, which for each cylinder 3 has at least one exhaust gas line 16. The exhaust gas line is respectively fluidly connected to the at least one outlet valve 6 of the respective cylinder 3 and serves in particular for discharging exhaust gas form the internal combustion engine 2. The exhaust gas lines 16 lead to an exhaust gas turbo charger 17 or a turbine of the exhaust gas turbo charger 17. For this purpose the exhaust gas turbo charger 17 or the turbine is for example constructed multi-branch. As an alternative it can also be provided that at least two of the exhaust gas lines 16 upstream of the exhaust gas turbo charger 17 are united and together lead to the exhaust gas turbo charger 17. Preferably all exhaust gas lines 16 are combined upstream of the exhaust gas turbo charger 17. The turbine of the exhaust gas turbo charger 17 can serve for driving the compressor 10, wherein in this case the compressor 10 is a part of the exhaust gas turbo charger 17. On the side of the exhaust gas turbo charger 17 facing away from the exhaust gas lines 16 a further line 18 is provided, which leads to a catalytic converter 19. Fluid flowing through the exhaust gas lines 16, in particular exhaust gas, thus flows through the exhaust gas turbo charger 17 and subsequently through the catalytic converter 19. Downstream of the catalytic converter 19 the fluid is again conducted into the external environment 13. It is noted that the exhaust gas turbo charger 17 is optional. The exhaust gas lines 16 can alternatively be connected to the catalytic converter 19 in a separate or already combined state.

(4) For heating the catalytic converter 19 in at least one operating state of the internal combustion engine 2, a heating device 20 is provided, which is for example constructed as a burner, which is operated with liquid or gaseous fuel. The heating device 20 is preferably integrated into the internal combustion engine 2, in particular into the cylinder head of the internal combustion engine 2. It is connected to the air distributor 7 via a line 21. Through the line 21 a cold air stream 22 can be conducted to the heating device 20, wherein a flow rate of the cold air stream 22, i.e., the mass or the volume per time unit, can preferably be adjusted with a valve 23. The valve 23 serves as cross section adjustment element in order to adjust the flow cross-section of the line 21. Of course the valve 23 can also be integrated in the heating device 20. In the heating device 20 the cold air stream 22 is heated up and subsequently conducted in the form of a hot air stream in the direction of the catalytic converter 19. The hot air stream 24 preferably has a high temperature, which is for example higher than a maximally permissible temperature of the catalytic converter 19.

(5) For this reason it is required to lower the temperature of the fluid conducted to the catalytic converter 19. For this purpose the hot air stream 24 is mixed upstream of the catalytic converter 19 with exhaust gas of the internal combustion engine 2 and/or with a cold fresh air stream 25 for adjusting a defined temperature. F or this purpose the hot air stream 24 is for example conducted to one of the exhaust gas lines 16 or as an alternative to a common exhaust gas line in which the exhaust gas lines 16, in particular all exhaust gas lines 16, are combined. The cold fresh air stream 25 like the cold air stream 22 is withdrawn form the air distributor 7. In particular the fresh air stream 14 is divided in the air distributor 7, which insofar represents the withdrawal point 26, into the cold air stream 22 and the cold fresh air stream 25. The cold air stream 22 is heated by means of the heating device 20, and is for example part of a chemical reaction. In particular, fuel is mixed with the cold air stream 22 and combusted. Correspondingly, the hot air stream 24, which originates from the cold air stream 22, is present downstream of the heating device 20.

(6) Upstream of the catalytic converter, the hot air stream 24 is combined with the cold fresh air stream 25. Particularly preferably, as shown, the cold fresh air stream 25 is conducted through at least one cylinder 3, in particular without being chemically altered. The corresponding cylinder 3 is thus deactivated, so that no combustion takes place therein. For example the cylinder 3 is operated in a trailing throttle mode. Hereby the at least one inlet valve 5 and the at least one outlet valve 6 of the corresponding cylinder 3 are operated so that the cold fresh air stream 25 is transported in the direction of the catalytic converter 19. The described method is preferably performed when the internal combustion engine 2 is deactivated. However, it can also be performed when the internal combustion engine 2 is only partially deactivated, wherein for example at least one of the cylinders 3 is active, i.e., fuel is combusted in this cylinder. Only the at least one cylinder 3 through which the cold fresh air stream 25 is conducted is deactivated or is operated in the trailing throttle mode.

(7) With such a drive device 1 a high mass stream of a heated fluid can be conducted to the catalytic converter 19 to heat the catalytic converter also when the internal combustion engine 2 is deactivated. The temperature of the fluid conducted to the catalytic converter 19 preferably corresponds to at least its operating temperature, however, it is lower than the maximally permissible temperature, above which damage to the catalytic converter 19 may occur. As explained above only a portion of the fresh air stream 14 is hereby heated in the form of the cold air stream 22 and subsequently supplied to the catalytic converter 19 as hot air stream 24. The other portion of the fresh air stream 14 is conducted around the heating device as cold fresh air stream 25, preferably through the at least one cylinder 3 of the internal combustion engine 2. Correspondingly, the temperature of the cold fresh air stream 25 is lower than the one of the hot air stream 24. By appropriately selecting the mass streams of the hot air stream 24 and the cold fresh air stream 25 the temperature of the fluid conducted to the catalytic converter 19 can be adjusted to a desired value. Thus it is possible to always operate the heating device at an optimal efficiency, without risking damage to the catalytic converter 19 when heating the catalytic converter.