Exhaust gas aftertreatment device for diesel engines of vehicles, preferably passenger cars

Abstract

An exhaust gas after treatment device for a diesel engine of a vehicle has at least one injection valve with an injection nozzle through which an exhaust gas treatment medium is injected into an exhaust pipe. At least one pump is provided that conveys the exhaust gas treatment medium to the at least one injection valve. At least one sensor and at least one control are also provided. The pump, the sensor, and the injection valve are connected to the at least one control. The at least one pump and the at least one control are combined to an assembly, and the assembly also includes the at least one injection valve.

Description

The invention relates to an exhaust gas after treatment device for diesel engines of vehicles, preferably passenger cars, according to the preamble of claim 1.

Such exhaust gas after treatment devices are employed mainly in trucks in order to treat the exhaust gas produced by the diesel engines in such a way that the nitrous oxides (NO, NO₂) are at least partially captured. For this purpose, a pump is provided that pumps a 32.5% urea/water solution as an exhaust gas after treatment medium form a reservoir and supplies it at a certain pressure to an injection valve. The valve meters the required amount of urea/water solution into a pressure-controlled airflow. In the case of trucks, the pressure is taken from the onboard supply system. In the case of a passenger car, the compressed air must be provided by a separate air compressor. The airflow entrains the injected urea/water solution. The emulsion that is produced in this way is supplied through an aerosol conduit to the injection nozzle at the exhaust pipe and is injected upstream of the catalyst into the exhaust pipe. The control, the different sensors, the injection nozzle at the exhaust pipe, or the pumps are partially arranged so as to be spatially far apart. Therefore, these individual components must be connected by a cable harness and the cables must be laid to all these components. Often, the cables must be placed in the vicinity of the exhaust where high temperatures are present.

The invention has the object to configure the exhaust gas after treatment device of the aforementioned kind such that, while it has a simple configuration, it can be mounted in a simple way in the vehicle.

This object is solved for the exhaust gas after treatment device of the aforementioned kind in accordance with the present invention with the characterizing features of claim 1.

In the exhaust gas after treatment device according to the invention at least the pump and the control are combined to an assembly. The complex laying of cables between these components is therefore not required so that the device can be mounted in a simple way.

Further features of the invention result from the dependent claims, the description, and the drawing.

The invention will be explained in more detail with the aid of an embodiment illustrated in the drawing. The drawing shows the exhaust gas after treatment device according to the invention in a schematic illustration.

For exhaust gas after treatment of diesel engines in trucks and passenger cars, the nitrous oxides (NO, NO₂) are reduced by a catalyst. For this purpose, a solution is employed which is introduced into the exhaust gas flow of the diesel engine. As a solution, advantageously 32.5% urea/water solution is used that is stored in a reservoir 1. The reservoir is located in a tank 2 for diesel fuel. A discharge line 3 extends into the reservoir 1; within the reservoir, the discharge line is advantageously connected to a filter 4. The discharge line 3 penetrates seal-tightly the reservoir 1 and is connected at the wall of the tank 2 to a conduit 5. The conduit branches to a pump block 6 that has two parallel-connected pump units 7, 8. Each one of the two pump units 7, 8 has a check valve 9, 10 that prevents return of medium into the reservoir 1. The two pump units 7, 8 are connected to an electric/electronic control 11.

By means of the pump units 7, 8, the medium is supplied through an outlet line 12, 13, respectively, to a conveying line 14 in which the medium flows to the control valve 15. Check valves 16, 17 are provided in the outlet lines 12, 13, respectively; they close toward the pump devices 7, 8. The control valve 15 is also connected to the control 11.

The pressure of the medium in the conveying line 14 is monitored by a pressure sensor 18 that is connected to the control 11.

In the drawing, the control valve 15 is in a closed position so that the medium cannot flow in the direction toward a throttle location 20 provided at the exhaust pipe 19. The throttle location 20 is a component of an injection valve 25 with which the exhaust gas treatment medium is injected into the exhaust pipe 19. The exhaust gas flowing through the exhaust pipe 19 takes up the injected exhaust gas treatment medium. When the control valve 15, controlled by the control 11, switches into its through position, the exhaust gas after treatment medium flows from the conveying line 14 through the control valve 15 into a conveying line 21 that is advantageously configured as an expansion hose. The conveying line 21 is connected to the throttle valve 20.

The temperature of the exhaust gas in the exhaust pipe 19 is measured by temperature sensor 22 that is connected by a bus 23, preferably a CAN bus, to the control 11.

The conveying line 21 is preferably heatable. In this case, a heating device 24 is provided that is arranged on the conveying line 21 or is integrated therein. This heating device 24 is also connected to the control 11.

The injection valve 25 can be provided optionally with a check valve 26 that closes toward the conveying line 21. By providing the check valve 26, the operational safety of the injection valve 25 is improved.

The onboard electric system 27 of the vehicle is connected to the control 11. The control 11 is mounted on a housing 28 in which the pump 6, its pressure sensor 18, and the control valve 15 are arranged. The housing 28 itself is a component of an assembly 31 which, in turn, is a part of the metering device 29 indicated in the drawing by a dashed line. In addition to the assembly 31 and the control 11, the metering device 29 contains the injection valve 25.

Since the important components of the metering device 29 are mounted in the housing 28, long cable lengths connecting the individual components of the after treatment device are not needed. A significant contribution to this is that the control 11 itself is provided on the housing 28 and, optionally, can be integrated into the housing 28. Accordingly, the important components of the after treatment device are arranged spatially very close together.

In the housing 28 these parts are protected against destruction, for example, caused by freezing.

The control 11 must only be provided with connecting possibilities for the onboard electric system 27, for the bus line 23, and for the heating device 24 of the conveying line 24.

The electrically heatable expansion hose 21 extends from the housing 28 of the metering unit or assembly 31 to the injection nozzle 25 at the injection location on the exhaust pipe 19. Through the injection valve 25 the exhaust gas treatment medium is metered into the exhaust gas flowing in the exhaust pipe 19.

When at low external temperatures the exhaust gas treatment medium freezes, the additional volume that is generated because of the freezing process can be forced through the injection valve 25 into the exhaust pipe 19 if it is not taken up by the heatable expansion hose 21.

Within the housing 28 of the assembly 31 a pump solenoid of the pump 6 can be permanently supplied with electric current without the pump being in conveying mode. The heating that is caused by this action is then used for thawing the assembly 31. In this way, a separate connection to the vehicle cooling system, which would be otherwise necessary for thawing, is not needed.

Outside of the housing 28, the expansion hose 21 is heated in the described way so that the exhaust gas treatment medium flowing through the expansion hose is heated. This has the result that also the injection valve 25 is heated to such an extent that possibly frozen exhaust gas treatment medium will thaw. The injection nozzle that is provided at the exit of the injection valve 25 can thus be heated in a reliable way so that it will not freeze shut.

Since the components that are present in the metering device are spatially very close together, the corresponding lines that are required between the control 11 and these components are thus short. Accordingly, a cable harness is not needed. All electrically controlled components are electrically contacted in the housing 28 or the metering device 29 by means of lead frames or flexible contact films. An electric line to the exhaust pipe 19 for the pressure sensor 18 is not required because it is arranged within the housing 28 itself. In the case of frozen exhaust gas medium, the pump 6 can be used as a heating element in the afore described way by permanent current supply to its solenoid so that the medium frozen within the pump is thawed.

Advantageously, the assembly 31 and the housing 28 are mounted directly on the tank 2 so that an additional external intake line for the exhaust gas treatment medium is not required.

Since the exhaust gas after treatment device is advantageously provided in passenger cars, in which—in contrast to trucks—a compressed air system is not present, the exhaust gas treatment medium can be easily metered in the described way into the exhaust gas flow within the exhaust pipe 19 without employing compressed air.

Along the exhaust pipe 19 that becomes very hot in operation there is no cable or electric line.

The described exhaust gas after treatment device is freeze-proof, has a compact configuration, and can be produced inexpensively. The device can also be used for trucks.

Claims

1.-20. (canceled)

21. An exhaust gas after treatment device for a diesel engine of a vehicle, the device comprising:

at least one injection valve with an injection nozzle through which an exhaust gas after treatment medium is injected into an exhaust pipe;

at least one pump conveying the exhaust gas treatment medium to the at least one injection valve;

at least one sensor;

at least one control;

wherein the at least one pump, the at least one sensor, and the at least one injection valve are connected to the at least one control;

wherein the at least one pump and the at least one control are combined to an assembly;

wherein the assembly comprises the at least one injection valve.

22. The device according to claim 21, wherein the at least one injection valve comprises a check valve that opens in a direction toward the injection nozzle.

23. The device according to claim 22, further comprising a throttle location arranged downstream of the check valve.

24. The device according to claim 21, wherein at least one of the at least one pump, the at least one sensor, and the at least one injection valve are connected electrically to the at least one control inside the assembly.

25. The device according to claim 21, wherein the at least one control has a connector for an onboard electric system of a vehicle.

26. The device according to claim 21, further comprising a control valve arranged upstream of the at least one injection valve.

27. The device according to claim 26, wherein the control valve is arranged in a housing.

28. The device according to claim 27, wherein the housing is a part of the assembly and the at least one pump is arranged in the housing.

29. The device according to claim 27, wherein the at least one sensor is arranged in the housing.

30. The device according to claim 29, wherein the at least one sensor is a pressure sensor.

31. The device according to claim 27, wherein the at least one control is connected to the housing.

32. The device according to claim 27, further comprising at least one additional sensor arranged outside of the housing, wherein the at least one control has a connector for the at least one additional sensor.

33. The device according to claim 32, wherein the at least one additional sensor is a temperature sensor.

34. The device according to claim 32, wherein the at least one additional sensor is arranged external to the assembly.

35. The device according to claim 27, wherein the at least one injection valve is connected by an expansion hose to the housing.

36. The device according to claim 35, wherein the expansion hose is heatable.

37. The device according to claim 27, wherein the housing is mounted on a diesel fuel tank of the vehicle.

38. The device according to claim 21, wherein the assembly is part of a metering device.

39. The device according to claim 37, wherein the metering device and the assembly form a mounting module.