EP2057359A1

EP2057359A1 - Injection system for an internal combustion engine, and internal combustion engine

Info

Publication number: EP2057359A1
Application number: EP07802790A
Authority: EP
Inventors: Andreas BRÜCKL; Adolf Einberger; Sebastian Fischer; Bernd Heisig; Yavuz Kurt
Original assignee: Siemens VDO Automotive AG
Current assignee: Continental Automotive GmbH
Priority date: 2006-08-25
Filing date: 2007-08-22
Publication date: 2009-05-13
Also published as: WO2008023031A1; DE102006039882B3

Abstract

Injection system for an internal combustion engine having at least one cylinder (Z1 to Z4), having at least one injector (18) which is coupled hydraulically to a fuel accumulator (16) and by way of which fuel can be injected into a combustion chamber (53) of one of the cylinders (Z1 to Z4) of the internal combustion engine, a high-pressure pump (14) for conveying fuel from a fuel tank (10) into the fuel accumulator (16), a return line (19, 46) which is arranged downstream of the high-pressure pump (14) and upstream of the fuel tank (10) and is configured for returning fuel from the high-pressure pump (14) and/or the injector (18) into the fuel tank (10), and a branch line (42) which branches off from the return line (19, 46) and is hydraulically coupled to an exhaust-gas section injector (47), by way of which fuel can be injected into an exhaust-gas section (56) of the internal combustion engine.

Description

description

Injection system for an internal combustion engine and Brennkraftma ^¬ machine

The invention relates to an injection system for a combustion ^¬ engine and an internal combustion engine.

For injecting fuels into the combustion chambers of an internal combustion engine, in particular a diesel internal combustion engine, injection systems are used, which have increasingly been designed in recent years as so-called "common rail" systems The fuel to be injected is currently present in the fuel storage at a pressure of up to 2000 bar.

Injection systems for internal combustion engines have pumps, by means of which fuel is conveyed to be introduced into combustion chambers of the internal combustion engine. Such a ^¬ injection systems for internal combustion engines place high demands on the accuracy of the REQUIRED ^¬ chen for injection of the fuel ^¬ fuel in the combustion chambers of the internal combustion engine injection pressure.

This is particularly important as more and more stringent, be adopted Gesetzesvor ^¬ regulations regarding the permissible pollutant emissions of internal combustion engines, which are arranged in motor vehicles. These make it necessary to carry out various measures by which the pollutant emissions are reduced. For example, the formation of soot is highly dependent on the preparation of the air / fuel mixture in the respective cylinder of the internal combustion engine. It is advantageous for the reduction of pollutant emissions, when the fuel injected very precisely in the cylinder ^¬ who can. As other measures for reducing the pollutants Missio ^¬ NEN of motor vehicles are in engine exhaust gas treatment systems in use, which ^¬ convert the pollutant Missio ^¬ NEN produced in each cylinder during the combustion process of the air / fuel mixture to into harmless substances. Especially with the ^¬ sel engines this coming particulate filter, preferably soot filter used. These must be regenerated at a certain loading with particles again.

From the textbook "Encyclopedia Engine Technology", published by Richard van Basshuysen / Fred Schäfer, 1st edition, April 2004, Friedrich Vieweg & Sohn Verlag, Wiesbaden, page 808, the regeneration of soot filters for an internal combustion engine, especially a diesel engine, known regeneration of the soot filter, it is burned off by hot exhaust gases. Dry soot but only burns sufficiently rapidly at temperatures above 550 degrees Celsius. Since the Abgastem ^¬ temperatures fail to do so, as a rule, additional measures must be taken. in order to burn the soot to allow to come to an active regeneration ^¬ systems are used. at these energy is released by a trip signal, to raise the exhaust gas temperature and so to burn the soot reliable. this is done example ^¬ by means of a burner, an electric heating, a late injection or by catalytic combustion can fuel additives mixed ^¬ to which lower the reaction temperature.

From EP 1 296 060 Bl an injection system for an internal combustion engine is known, with a prefeed pump, can be promoted with the fuel from a fuel tank to the suction side of a high-pressure pump. A high-pressure pump connected hydraulically downstream of the prefeed pump then delivers fuel to a fuel reservoir, from where it then discharges to injectors hydraulically coupled to the fuel reservoir. can be shared. In the injection system, control valves are arranged, by means of which, given suitable activation in the fuel reservoir, a predetermined pressure dependent on the operating parameters of the internal combustion engine can be achieved.

The object of the invention is to sheep ^¬ fen an injection system for an internal combustion engine and an internal combustion engine, by the operation of the internal combustion engine with very low pollutant emissions and a simple structure of the injection system are made possible.

The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

According to a first aspect, the invention features an injection system for an internal combustion engine, with at least one with a fuel reservoir hydraulically coupled injector, with the fuel of a high pressure pump for pumping fuel injected into a combustion chamber of a cylinder of the internal combustion engine from a power ^¬ fuel tank in the fuel storage, a downstream of the high-pressure pump and upstream of the fuel storage ^¬ ordered return line, which is designed for returning fuel from the high-pressure pump and / or the injector in the fuel tank and a branched off from the return line branch line, which is hydraulically coupled to a Abgastraktinjektor with which fuel can be injected into an exhaust tract of the internal combustion engine.

This is particularly advantageous because it makes it possible to dispense with an additional delivery unit, such as an electric delivery pump for supplying the exhaust gas jet injector. Rather, the hitherto used high-pressure pump can be used in the injection system for the supply of the exhaust-gas injector with fuel, without it to have to change. In particular, can be diverted via the Abzweiglei ^¬ tion, which is hydraulically coupled to the Abgastraktinjektor, fuel for the Abgastraktinjektor, without thereby affecting the delivery capacity of the high-pressure pump to ^¬ impressive.

In an advantageous embodiment of the invention, the return line is an injector return line of the at least one injector. This has the advantage that no change of Vorförderpumpen- / high-pressure pump assembly is required. Furthermore, it is possible to provide fuel that is not required by the injectors for the exhaust-gas injector.

In a further advantageous embodiment of the invention, the return line is a downstream of the high pressure pump and upstream of the fuel reservoir branching pump ^¬ return line. This is advantageous because an otherwise existing pressure relief valve of the prefeed pump can be omitted. In addition, it is possible to provide a constant pressure at the exhaust-gas injector even in the event of a lack of injection at the injectors.

In a further advantageous embodiment of the invention, the branch line branches off in the return line at a branch point and downstream of the branch point and upstream ^{¬ of} the fuel tank, a check valve is arranged ^¬ assigns. This is particularly advantageous because it makes it possible to provide a defined pressure level for the exhaust tract injector.

According to a second aspect, the invention features an internal combustion engine with an injection system where ^¬ having a particle filter in the exhaust tract and strö ^¬ mung technically couplable with the combustion chamber, and the Abgastraktinjektor downstream of the combustion chamber and upstream ^¬ Windwärts of the particulate filter is arranged. This is particularly advantageous since permit fuel upstream of the particulate filter ^¬ Windwärts injected into the exhaust gas tract of the internal combustion ^¬ machine and so the exhaust gas temperature can be increased so as to regenerate the particulate filter. Furthermore, such an internal combustion engine is characterized by a simple structure.

Advantageous embodiments of the invention are explained below with reference to the schematic drawings.

Show it:

1 shows a block diagram of an injection system for an internal combustion engine in a first embodiment,

FIG. 2 shows a block diagram of the injection system for an internal combustion engine in a second embodiment,

3 shows a block diagram of the injection system for an internal combustion engine in a further embodiment, and

Figure 4 is a schematic view of an internal combustion engine.

Elements of the same constructions or functions are identified across the figures with the same reference numerals.

The injection system illustrated in Figure 1 for an internal combustion engine 50 (Figure 4) has a fuel tank 10 from which by means of a prefeed pump 12 fuel ge ^¬. The prefeed pump 12 is designed with preference as Flü ^¬ gel cell pump. However, it can also be another type of pump, z. B. a gear pump or a gerotor pump can be used for the pre-promotion. The prefeed pump 12 can be connected to a drive shaft, not shown, which is coupled to a motor shaft of the internal combustion engine 50. are driven nisch. Alternatively, however, it is also possible to use an electrically operated prefeed pump, whereby a control of the delivery rate of the prefeed pump 12 is independent of the delivery rate of other pumps possible.

Downstream of the prefeed pump 12, a high-pressure pump 14 for conveying the fuel in a fuel reservoir 16 is arranged. The fuel reservoir 16 is hydraulically coupled to the high pressure pump 14 via a fuel storage supply line 44. The high pressure pump 14 may preferably comprise as Radi ^¬ alkolbenpumpe or formed as a series of piston pump with several Zylin ^¬ dereinheiten be, as they are known for use in injection systems of internal combustion engines.

The fuel reservoir 16 is further hydraulically coupled via lines to an injector 18 or a plurality of injectors 18. Each of the injectors 18 is associated with a combustion chamber 53 of the internal combustion engine 50 and each can be so angesteu ^¬ ert that fuel is injected into the combustion chamber 53. By the high-pressure pump 14, the fuel which is to be injected by means of the injectors 18 into the combustion chambers 53 of the internal combustion ^¬ engine 50, a high injection pressure ^¬ reach a ^¬ .

Excess fuel may be returned to the fuel tank 10 from the injectors 18 via an injector return line 46.

Between the prefeed pump 12 and the high-pressure pump 14, a Volumenstromsteuer- / control valve 22 is arranged, with which the fuel flow from the feed pump 12 in the high ^¬ pressure pump 14 is adjustable. By means of a pressure sensor 25, by means of which the fuel pressure in the fuel reservoir 16 can be determined, as well as optionally as a function of further input variables, the volumetric flow control / regulating valve 22 can be controlled such that a low-pressure side regulation of the high-pressure pump 14 supplied power ^¬ material flow is possible.

The high pressure pump 14 is connected by means of a downstream of the high pressure pump 14 and upstream of the fuel reservoir 16 branched pump return line 19 with a pressure control valve 20, which is preferably controlled depending on the determined by the pressure sensor 25 fuel pressure in the fuel reservoir 16. Upon exceeding a pre give ^¬ NEN fuel pressure in the fuel reservoir 16, the pressure control valve can open 20 and a part of the conveyed from the high ^¬ pressure pump 14 the fuel can be returned through the pump return line 19 into the fuel tank 10 degrees.

Downstream of the prefeed pump 12 and upstream of the volumetric flow control / regulating valve 22 branches off a purge line 29, the output side opens into the housing of the high-pressure pump 14, so that it is possible, the housing of Hochdruckpum ^¬ pe 14 during operation with fuel do the washing up. This cooling and lubrication of the high-pressure pump 14 can be effected. The fuel used for Spülungszwecken can then be returned from the housing of the high pressure pump 14 via a purge return line 35 into the fuel tank 10.

In the purge line 29, a purge line throttle 34 and hydraulically in series with a purge line valve 32 are further arranged. The purge line throttle 34 may limit the fuel flow ^¬ through the purge line 29.

Through the purge line valve 32, the branching off via the purge line 29 Kraftstoffström be released when a predetermined fuel pressure at the output side of the pre-feed pump 12 is exceeded. It must be ensured that the flushing of the high pressure pump 14 until a ^¬ recognized when the operating pressure of the high pressure pump 14 reaches is. This is necessary because only way to ensure that no fuel via the purge line abge ^¬ branches, is 29 as long as the pressure increase on the suction side of the high pressure pump 14 is not yet complete. This can be achieved that the pressure build-up on the suction side of the high-pressure pump 14 is not delayed.

To protect the units arranged in the injection unit, in particular the pumps 12, 14 and the control valves 22, 20, filters 36, 40 are arranged at suitable points. Thus, to protect the prefeed pump 12 hydraulically between the fuel tank 10 and the prefeed pump 12, a first filter 36 is provided. Furthermore, a second filter 40 is arranged to protect the pressure regulating valve 20.

The pressure regulating valve 20 is arranged in the pump return line 19, which is the output side coupled to the Injektorrücklauflei ^¬ device 46 of at least one injector 18. The purge return line 35, the pump return line 19 and the injector return line 46 from the injectors 18 are preferably returned to the fuel tank 10.

At a branch point 41 downstream of the high-pressure pump 14 and upstream of the fuel tank 10 branches off from the Pum ^¬ penrücklaufleitung 19 from a branch line 42 which is hydraulically coupled to a Abgastraktinjektor 47. With the exhaust-gas injector 47, fuel can be injected into an exhaust tract 56 of the internal combustion engine 50, as described below. Downstream of the branching point 41, a check valve 48 is arranged, which can be adjusted so that a sufficient pressure is applied to the exhaust-gas injector 47.

Between the entry into the fuel tank 10 and the exit from the fuel tank 10, a Tanküberbrückungs ^¬ line 49 is arranged, via which from the pump return line 19 and / or the injector return line 46 flowing back fuel directly to the first filter 36 can be performed.

In Figure 4, the internal combustion engine 50 is shown with an intake section 51, an engine block 52, a cylinder head 54 and the exhaust gas duct 56. The intake duct 51 includes vorzugswei ^¬ se a throttle valve 58, an accumulator 60 and a suction pipe 62. The suction pipe 62 is out led to a cylinder Zl via an inlet channel into the combustion chamber 53 of the engine block 52. The engine block 52 further includes a crankshaft 64, which is coupled via a connecting rod 66 with a piston 68 of the cylinder Zl.

The cylinder head 54 includes a gas inlet valve 70 and a gas outlet valve 72 and the injector 18.

In the exhaust tract 56, a particulate filter 88 is arranged. The particulate filter 88 is preferably a soot filter. Downstream of the combustion chamber 53 and upstream of the Partikelfil ^¬ ters 88 of Abgastraktinjektor 47 is arranged, may be injected with the fuel into the exhaust tract 56th

In addition to the cylinder Zl further cylinders Z2 to Z4 are preferably provided. In further preferred embodiments (not shown), the internal combustion engine has five, six or eight cylinders.

In the following, the function of the injection system for the internal combustion engine 50 will be described:

The prefeed pump 12 delivers fuel from the fuel ^¬ tank 10, wherein impurities in the first filter 36 between the fuel tank 10 and the feed pump 12 can be zurückgehal ^¬ th. The fuel then passes to the volumetric flow control / control valve 22. By the volumetric flow control / control valve 22, the high pressure pump 14 becomes so much fuel provided as required by the fuel storage 16.

By means of the high pressure pump 14, the fuel is supplied via the fuel storage supply line 44 to the fuel reservoir 16. From the fuel reservoir 16, the fuel is supplied to the injectors 18, and injected from them into the combustion chambers 53 of the internal combustion engine 50.

The fuel pressure required for the fuel tank 16 is determined by the pressure regulating valve 20. If the pressure in the fuel accumulator feed line 44 and thus too strong in the fuel accumulator 16 at or to be selectively reducing the pressure in the fuel reservoir 16, so 20 fuel may be discharged by means of the pressure regulating valve in the fuel ^¬ tank 10th Fuel is further returned from the purge return line 35 and the injector return line 46 from the injectors 18 to the fuel tank.

Via the tank bridging line 49, fuel flowing back from the pump return line 19 and / or the injector return line 46 can be conducted directly to the first filter 36. This is particularly advantageous because the fuel flowing back from the pump return line 19 and / or the injector return line 46 may have a higher temperature than the fuel pumped from the fuel tank 10. At low ambient temperatures, such an unimpeded fuel flow through the first filter 36 can be achieved.

The delivery rate of the mechanical prefeed pump 12 as well as the high-pressure pump 14 is determined by the drive speed of the pump. The input speed of the feed pump 12 and the high pressure pump 14 is determined by the ratio of the rotational ^¬ number of the respective pump to the speed of the motor. In the starting phase of the internal combustion engine 50, the scavenging valve 32 is closed, so that a pressure build-up can take place on the intake side of the high-pressure pump 14. The Hubvolu ^¬ men the prefeed pump 12 is chosen to be much larger than the delivery volume of the high-pressure pump 14 so as to ensure a sufficient flow rate to the intake side of the high-pressure pump 14 at start. If the pressure build-up on the suction side of the high-pressure pump 14 is completed, the scavenging valve 32 opens. The fuel flow branched off from the feed pump 12 for purging the high-pressure pump 14 via the scavenging line 29 and the scavenging return line 35 can now reach such high pressure in the scavenging return line 35, that thus also a contribution to the supply of Abgastraktinjektors 47 with fuel from the purge return line 35 is possible.

A specific increase in the exhaust temperature, to aid in regeneration of the particulate filter 88 is performed vorzugswei ^¬ se in a partial load operation or the full load operation of the internal combustion engine 50th For this purpose, it is necessary to lead fuel via the branch line 42 to the exhaust-gas injector 47. The injection system is designed so that in a full load operation of the internal combustion engine 50 a maximum benö ^¬ tigte fuel delivery volume flow of the high-pressure pump 14 is ensured. In all other operating points of the internal combustion engine 50, it is sufficient if the high-pressure pump 14 promotes a comparatively lower fuel delivery volume flow.

By supplying the Abgastraktinjektors 47 with force ^¬ material from the injection system can be avoided that other components such. As an electric fuel pump, which may be arranged for example in the fuel tank, are necessary for the supply of Abgastraktinjektors 47 with fuel. The embodiment of the injection system illustrated in FIG. 2 differs from the first embodiment in that the branch line 42 hydraulically coupled to the exhaust-gas injector 47 branches off from the injector return line 46 at the branching point 41. The non-return valve 48 for adjusting a sufficient pressure on Abgastraktinjektor 47 of the branch-off point is located downstream in the injector ^¬ return line 46 41st

Furthermore, the feed pump 12 is hydraulically coupled on the output side with egg ^¬ nem form control valve 28. When exceeding a predetermined fuel pressure at the output side of the feed pump 12 so that a portion of the funded by the feed pump 12 fuel to the suction side of the prefeed pump 12 are returned. As a result, the fuel pressure at the output side of the prefeed pump 12 can be limited.

In this embodiment, the back-flowing from the injectors 18 for the fuel Abgastraktinjektor 47 can be ge ^¬ uses. The injection system can therefore still be with the normally present form control valve 28 Betrie ^¬ ben.

The embodiment of the injection system shown in FIG. 3 differs from the embodiment of FIG. 2 in that the branch line 42 hydraulically coupled to the exhaust tract injector 47 branches off at the branch point 41 downstream of the hydraulic connection of the injector return line 46 and the pump return line 19. The non-return valve 48 for adjusting a sufficient pressure on Abgastraktinjektor 47 downstream of the branch ^¬ point 41 and upstream of the fuel tank 10 angeord ^¬ net. The operation of the fuel injection corresponds We ^¬ sentlichen the embodiment of the injection system of FIG. 2 This embodiment is particularly advantageous when the pressure conditions in the injector return line 46 and the pump return line 19 substantially coincide, since in this case otherwise required in both return lines 19, 46 required components (such as valves) only once again.

Claims

claims

1. injection system for an internal combustion engine, with

at least one injector (18) hydraulically coupled to a fuel reservoir (16), with which fuel can be injected into a combustion chamber (53) of a cylinder (Z1 to Z4) of the internal combustion engine,

a high-pressure pump (14) for conveying fuel from a fuel tank (10) into the fuel reservoir (16),

- A downstream of the high pressure pump (14) and upstream ^{¬ of} the fuel tank (10) arranged return line

(19, 46) configured to recirculate fuel from the high pressure pump (14) and / or the injector (18) into the fuel tank (10), and

- One of the return line (19, 46) branching branch line (42) which is hydraulically coupled to a Abgastraktinjektor (47), with the fuel in an exhaust tract (56) of the internal combustion engine can be injected.

2. Injection system according to claim 1, wherein the return line is an injector return line (46) of the at least one injector (18).

3. Injection system according to claim 1, wherein the return line is a downstream of the high-pressure pump (14) and upstream of the fuel reservoir (16) branching Pumpenrücklauflei ^¬ tion (19).

4. Injection system according to one of the preceding claims, wherein the branch line (42) in the return line (19, 46) branches off at a branch point (41) and downstream of the Ab ^¬ branch point (41) and upstream of the fuel tank (10) a check valve (48 ) is arranged.

5. Internal combustion engine with an injection system according to one of the preceding claims, wherein the exhaust tract (56) has a particle filter (88) and fluidly coupled to the combustion chamber (53), and the Abgastraktinjektor (47) downstream of the combustion chamber (53) and upstream of Particle filter (88) is arranged.