EP2511512A1 - Spill device - Google Patents

Abstract

The internal combustion engine (1) has an intake duct (2), an exhaust gas duct (3), a regulating or control unit, a burner (6) and a fuel supply unit communicating with the burner. The fuel supply unit has a dosing valve, a sensor, a valve and a fuel filter, where a catalytic converter (7a) is provided. An independent claim is included for a method for operating an internal combustion engine.

Description

Internal combustion engine, in particular with a fuel-Absteuermöglichkeit and a return line, preferably in the fuel supply system for exhaust aftertreatment systems.

Such systems are for. B. known from the DE 10 2008 002 003 , There, a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine is described, wherein the fuel injector is connected via a return line to a reservoir.

Furthermore, systems are known in the field of exhaust aftertreatment, which provide no possibility of venting at a standstill.

For the fuel supply of the exhaust aftertreatment system - the burner - the fuel is branched off before the fuel metering unit (ZME / eng .: FCU) and fed via a fuel line to the metering device of the burner system. By activating the so-called shut-off valve, the inlet for the fuel in the metering device is released and is at the pressure of the low-pressure circuit - generated by the fuel delivery pump - in front of the metering valves. As long as the metering valves are not activated, the fuel is kept in the supply system. If requested, the DV2 is then controlled with a low frequency via a software-supported splitting algorithm and thus measures the quantity required for torch start at. After the dosing valve doses the maximum amount for combustion and the burner is operated stably, the DV1 automatically switches on. This ensures through its injected into the exhaust system and on the diesel oxidation catalyst (DOC) reactive amount for the necessary temperature increase for the regeneration of the diesel particulate filter (DPF).

Such systems do not provide adequate venting capabilities without active burner start-up. If activation of the burner is not possible despite necessary system ventilation, the dosing valves can only be connected if certain motor conditions prevail, eg. B. high temperature before the DOC (> 300 ° C).

Furthermore, when all the actuators (SV, DV1 and DV2) in the dosing unit are deactivated, the fuel volume is included. B. Post-heating effects - leads to strong pressure increase.

In the period in which no scheduled regeneration or rinsing takes place, it comes with the trapped fuel volume to aging effects, which increase significantly by the temperature increase and thus can be critical for the system operation.

It is the object of the present invention to avoid the disadvantages mentioned above and to provide a device which ensures safe and economical operation under a wide range of operating conditions.

The object of the present invention is achieved by a device according to claim 1.

The introduction of a shut-off device provides a circuit which upon opening the shutoff valve provides for a permanent flow of fuel in the first stage of the system.

Thus, the first stage of the fuel system can be vented decoupled from engine constraints or active burner operation. Regardless of bleeding operations, a bleeder avoids a pressure increase due to re-heating effects, as the fuel pressure can relax over the additional path even after SV, DV1 and DV2 have been deactivated.

Furthermore, a Absteuervorrichtung offers advantages in terms of pressure stability in the fuel system. Due to the permanent flow, there is less positive and negative acceleration of the fuel column, which ensures pressure waves with a lower amplitude level, especially in the case of frequency-controlled metering valves. A further advantage is that the continuous flushing in connection with the removal of the fuel in the fuel system can not cause deposits, in particular due to premature aging of the thermal stress exposed fuel. Of particular advantage is such a solution in view of the use of vegetable oils, since, for example, no rapeseed oil deposits can occur when the internal combustion engine is operated with rapeseed oil.

The creation of a unit which provides an additional cross section as a branch besides the normal flow direction is advantageous. This branch can be designed both as a free cross-section, as well as the hydraulic elements, such. As a throttle or orifice include, it is a measure to prevent strong pressure oscillations in the fuel system. Furthermore, strong pressure increases due to the introduction of temperature on the fluid are prevented. Furthermore, the fuel aging is prevented by unnecessary temperature increases.

Figur 1:

eine schematische Darstellung einer Verbrennungskraftmaschine mit Abgasnachbehandlung,

Figur 2:

eine schematische Darstellung der Kraftstoffversorgungseinheit,

Figur 3:

ein Vergleich des Druckverlaufs im Kraftstoffsystem mit und ohne Absteuervorrichtung,

Figur 4a:

eine Absteuervorrichtung,

Figur 4b:

drei Querschnittsvarianten in der Absteuervorrichtung gemäß Fig. 4a.

Further advantages, features and details of the invention will become apparent from the dependent claims, the following description of a preferred embodiment and from the drawings. These show in:

FIG. 1:

a schematic representation of an internal combustion engine with exhaust aftertreatment,

FIG. 2:

a schematic representation of the fuel supply unit,

FIG. 3:

a comparison of the pressure curve in the fuel system with and without Absteuervorrichtung,

FIG. 4a

a diversion device,

FIG. 4b:

three cross-sectional variants in the Absteuervorrichtung according to Fig. 4a ,

An internal combustion engine 1 is in the in FIG. 1 illustrated embodiment, a 4-cylinder auto-ignition internal combustion engine 1, which may be equipped with a common-rail injection system, exhaust turbocharging and exhaust gas recirculation and of course any other cylinder numbers, in particular 1, 2, 3, 5, 6, 8, 10, 12, 16 , etc. may have. In the embodiment, the internal combustion engine 1 is supplied via a fresh gas line system 2 combustion air, while the fuel is injected via the injection system directly into the individual cylinder combustion chambers. The exhaust gas is discharged into an exhaust manifold 3 and fed there via an exhaust pipe 4 an exhaust aftertreatment system 5.

The exhaust aftertreatment system 5 has a burner 6 and a catalyst and / or particulate filter 7. In the embodiment, a catalyst 7a and a particulate filter 7b are provided. In principle, all known devices and device combinations suitable for exhaust aftertreatment can be present here. Thus, a particle filter 7b may be present alone, in which case the particles filtered out of the exhaust gas and stored in the particle filter 7b are burned by the burner 6. However, it can also be provided that a combination of catalyst 7a and particulate filter 7b are present, in which case the possible configurations as SCR catalyst (selective catalytic reduction), oxidation catalyst and NOx storage catalyst, in each case in combination with particulate filter 7b, are present , In this case, the burner 6 is used to increase the exhaust gas temperature and to initiate the respective reaction in the corresponding catalyst 7a. Finally, it is also possible to use only one catalytic converter 7a in accordance with the previous possibilities, in which case the burner 6 is also used to increase the exhaust gas temperature and to initiate the corresponding reaction in the catalytic converter 7a.

In the exemplary embodiment, the exhaust gas is passed through the exhaust pipe 4 and the burner in full flow through the catalyst 7a and particulate filter 7b and leaves the system via an exhaust pipe 8. In the invention, it is of course also possible, the exhaust aftertreatment system 5 in one in the side stream or isolated system.

The burner 6 has a burner housing 9, to which or in which the essential burner components are attached, and a combustion chamber 10 connected to the burner housing 9, which projects into the exhaust gas conduit 4. The combustion chamber 10 has an opening 11 in the flow direction of the exhaust gas toward the catalytic converter 7a, into which, for example, swirling components can be inserted. The burner 6 is - shown by arrows 12a, 12b - fuel and combustion air supplied. The exhaust aftertreatment system is controlled by an electronic control device, which may be part of the control system for the internal combustion engine 1. This control device becomes necessary data, such as exhaust gas temperature upstream of the burner 6, downstream of the burner 6 and in the exhaust line 8 (possibly also in the catalytic converter 7a and the particle filter 7b), and optionally also pressure values in the exhaust gas flow upstream of the catalytic converter 7a and behind the particle filter 7b or in others Constellation of each existing components determined and forwarded. From further stored in the controller maps further data can be stored and, if necessary, queried.

In FIG. 2 the fuel removal from a tank 23 to a fuel filter 25 via fuel lines 29, towards a disengageable and switchable dosing unit 30, is shown. This fuel-carrying system can be vented by means of Absteuervorrichtung 24 and avoids a temperature input to a liquid contained in a trapped volume in that the liquid is returned via the return line 22 of the fuel line 21 of the burner 1 in the tank 23 of the internal combustion engine. Such a device can be used in particular in fuel systems of exhaust aftertreatment used, especially in burners, eg. For DPF regeneration.

As soon as the shutoff valve 20 is actuated via the engine control 31, the fuel pressure, which is measured via the pressure sensor 32, builds up in the space behind the shutoff valve as a result of the inflow of the fuel. With sufficient fuel pressure, the metering valve burner 18 and the metering valve 19 can in turn be controlled by the motor controller 31. By high-frequency evaluation of the pressure signals of the pressure sensor 32, 15 and 17 in the engine controller 31, the operating state of the metering valves 18 and 19 is determined so as to properly control the default amounts of fuel.

FIG. 3 shows a comparison of the pressure curve over time in the fuel system with and without Absteuervorrichtung.

The representation according to FIG. 4a shows an in FIG. 2 used Absteuervorrichtung 24 with return 22nd

In FIG. 4b three cross-sectional variants of the discharge opening are shown. The first variant shows a free circular cross-section. In the second variant, a hydraulic throttle is shown. A hydraulic shutter shows variant three in FIG. 4b ,

reference numeral

1

Internal combustion engine

2

Fresh gas line system / intake system

3

Exhaust manifold / exhaust tract

4

exhaust pipe

5

aftertreatment system

6

burner

7a

catalyst

7b

particulate Filter

8th

exhaust pipe

9

burner housing

10

combustion chamber

11

opening

12a, 12b

arrows

13

injection

14

Valve

15

pressure sensor

16

Valve burner

17

Pressure sensor burner

18

Dosing valve burner

19

metering valve

20

Shutoff valve

21

Fuel line burner

22

returns

23

tank

24

Absteuervorrichtung

25

Fuel filter

26

Fuel supply unit

27

Fuel pump

28

Control unit

29

Fuel line

30

switchable dosing unit

31

Motor control / control unit

32

pressure sensor

Claims (10)

Internal combustion engine (1), comprising at least one intake tract (2), at least one exhaust gas tract (3), at least one control unit (31) and at least one burner (6) and a fuel supply unit (26) communicating with the burner (6). and at least one diversion device (24). Internal combustion engine according to claim 1,
characterized in that the fuel supply unit (26) has at least one metering valve (18, 19). Internal combustion engine according to claim 1 or 2,
characterized in that the fuel supply unit (26) has at least one sensor (15, 17). Internal combustion engine according to one or more of the preceding claims,
characterized in that the fuel supply unit (26) has at least one valve (14, 16). Internal combustion engine according to one or more of the preceding claims,
characterized in that the fuel supply unit (26) has at least one return (22). Internal combustion engine according to one or more of the preceding claims,
characterized in that the fuel supply unit (26) comprises at least one fuel filter (25). Internal combustion engine according to one or more of the preceding claims,
characterized in that the fuel supply unit (26) has at least one fuel delivery pump (27). Internal combustion engine according to one or more of the preceding claims,
characterized in that it comprises at least one particulate filter (7b). Internal combustion engine according to one or more of the preceding claims,
characterized in that it comprises at least one catalyst (7a). Method for operating an internal combustion engine,
characterized in that a device according to one or more of the preceding claims is used.

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