DE19945544A1 - Fuel supply system for a spark ignition internal combustion engine and method for operating such an internal combustion engine - Google Patents

Abstract

Known fuel supply systems have a blow-in valve that can deliver a fuel-air mixture directly into a combustion chamber. However, if large injection quantities are required, as is the case, for example, with high engine loads, problems can arise with the quality of the mixture preparation. DOLLAR A A fuel supply system for a spark-ignition internal combustion engine is proposed, which has at least one injection valve arranged in or on a cylinder head, to which fuel and a gaseous medium are supplied under pressure in order to use the injection valve to direct a fuel-medium mixture into a combustion chamber Deliver internal combustion engine. According to the invention, at least one further injection valve is provided which, in certain operating areas of the internal combustion engine, in addition to dispensing the fuel-medium mixture by means of the injection valve or temporarily instead of dispensing the fuel-medium mixture by means of the injection valve, dispenses fuel into an intake region of the internal combustion engine. DOLLAR A The fuel supply system according to the invention is intended for spark ignition internal combustion engines.

Description

The invention relates to a fuel supply system for a spark ignition internal combustion engine according to the genus of the An Proverbs 1 and 2 and a method for operating a Internal combustion engine with such a fuel supply system stem.

A fuel supply system is already known (EP 0 308 467 B1), the one attached to a cylinder head brought distribution board, in which both Brenn material as well as air under pressure in the cylinder head brought blowing valves is guided. For this are in the Distribution rail corresponding fuel lines and air lines to the injection valves provided. Each insert seventil has a conventionally constructed Electromagnetically actuated fuel injector on, the fuel in an inside the injector can deliver intended mixture formation chamber. The Indian Mixture chamber fuel is then Prepared with compressed air and mixed education chamber partially evaporated. The one so prepared Fuel continues to enter a dispensing area of the on Blow valve, which is an electromagnetically actuated valve having. In an open position of a valve closing body of the solenoid valve of the dispenser  that in the mixture formation chamber becomes rich Fuel-air mixture then with a relatively low Pressure of, for example, 7 to 8 bar from an outlet opening of the injection valve directly into the combustion chamber blown. The distributor is for both fuel and also provided for the air supply to the injection valves.

Are from the known fuel supply system or but the injection valve requires large injection quantities, as is the case, for example, with high engine loads, there may be problems with the quality of the mixture preparation come because the injection valve is only a certain maximum Can provide the amount of fuel with good preparation. The same problem also applies to a fuel supply system, which uses direct injection valves for petrol Direct injection. Give direct injection valves the fuel at a relatively high pressure in a direct manner Form of a fuel cloud consisting of the finest droplets into a combustion chamber of the internal combustion engine. At abver However, there is no longer a higher amount of fuel complete preparation of the from the direct injection valve given fuel and no optimal air utilization in the Combustion chamber. Even with injection valves, none can be full constant preparation of the gas emitted by the injection valve Obtain a fuel-air mixture. All of this means that there is a wetting of the cylinder inner walls and the Piston surface can come with fuel. Something like that but leads to incomplete combustion of the burner in the combustion chamber, causing an increase in damage components in the exhaust gas. Particularly affected of which are internal combustion engines that have a supercharger air drawn in, for example by means of an exhaust gas turbocharger, have, because these engines refer to the Zy  lindervolume relatively high injection quantities of fuel need.

The present invention has for its object that Generic fuel supply system to continue in this way the one in all areas of operation with regard to Consumption and exhaust emission optimal mixture preparation in the internal combustion engine.

This object is achieved according to the invention by a fuel guidance system with the features of claims 1 or 2 solved. Furthermore, the invention comprises a method for operation an internal combustion engine with the internal combustion engine material supply system with the features of claim 7.

The fuel supply system according to the invention for a spark ignition internal combustion engine with the features of the An Say 1 or 2 has the advantage that even high performance in the entire speed range from the internal combustion engine can be provided without the proportion of damage components in the exhaust gas.

The fuel injection system according to the invention offers the Possibility to burn the necessary for the mixture formation material in addition to the direct delivery into the combustion chamber by means of of the injection valve in one embodiment or by means of Direct injection in the other intended execution form additionally over the intake area of the internal combustion engine feed the machine. A control unit controls this Valve assigned to the combustion chamber (injection valve or direct injection valve) and the additional injection valve in the on suction range depending on the operating range of the Internal combustion engine and determines their respective throughput. The additional fuel is particularly useful  dispensing and feeding via the suction area essentially provided in the higher load range of the internal combustion engine. Due to the upstream fuel delivery in the intake it can be rich for direct fuel delivery to the distillery Valve provided for space with an inexpensive smallest / largest quantity ratio (spread) are formed because the pro Working cycle fuel quantity to be dispensed in two ways is feasible. A harmful drop in fuel pressure with direct delivery only into the combustion chamber, which is particularly harmful in the low load range thereby preventing and in particular the mixture formation in the important low-load area improved. The direct one Fuel supply in the combustion chamber required components of the fuel supply system can be advantageous lower total mass flow rates at full load than was previously the case with direct injection only tongue or injection was the case. This reduces the Friction power in the fuel pump and when it is charged Internal combustion engines in the compressor and therefore leads to a Reduction of fuel consumption. In the invention according fuel supply system with an injection valve in The air-assisted feed system can also add a cylinder head be designed for increased blow-out pressures (at least 10 bar), which means that the blowing point can be freely selected is possible.

It is particularly advantageous that at times sole Operation of the internal combustion engine with an additional injection valve an increase in temperature at the injection valves or can be achieved on the direct injection valves because these no longer have fuel in this duty-free period to be cooled so that it can then take place through the Temperature rise at the injection valves or direct injection  spray valves to dismantle any existing storage stake comes.

By the measures listed in the subclaims are advantageous further developments and improvements in Claim 1 or 2 specified fuel supply system for a spark ignition internal combustion engine possible.

Embodiments of the invention are in the drawing shown and in the description below he purifies. Show it:

Fig. 1 shows a partial section of an internal combustion engine having a fuel supply system according to a first embodiment of the invention,

Fig. 2 shows a partial section of an internal combustion engine having a fuel supply system according to a second embodiment of the invention,

Fig. 3 is a diagram of abgege of the internal combustion engine surrounded power plotted against the speed,

Fig. 4 is a diagram of the operating areas of the internal combustion engine with different operating modes.

Fig. 1 shows a section through an internal combustion engine ne according to a first embodiment of the invention. The internal combustion engine has a cylinder head 1 , in which an injection valve 2 is accommodated. The Einla seventil 2 has, in a known manner, a non-Darge, electromagnetically operable fuel injector, which can deliver fuel into a mixture formation chamber or into a mixture formation area inside the injection valve 2 . In the mixture formation chamber or in the mixture formation area, the fuel injection valve, which is not shown in detail above, is then mixed with fuel and a gaseous medium supplied to the mixture formation chamber or in the mixture formation area under pressure, so that the fuel in the mixture formation chamber or in the mixture formation area is partially distributed to be able to evaporate. The fuel thus prepared passes thereafter, controlled by a further, not shown, electromagnetically or piezoelectrically actuatable valve, in the form of a fuel-medium mixture from an outlet opening 5 of the injection valve 2 directly into the combustion chamber 7 of a cylinder 8 of the internal combustion engine. A piston 10 is movably accommodated in the cylinder 8 in a known manner. To ignite a closed fuel-medium mixture in the combustion chamber 7 , a spark plug ze 6 is provided. The gaseous medium can be air or air with mixed exhaust gas or also air with mixed fuel. There is therefore an internal combustion engine with internal mixture formation in conjunction with an air-assisted injection system. The construction and operation of such injection valves is also known to the person skilled in the art, for example, from SAE paper 98P-136, 1988, Rodney Houston, Geoffrey Cathcart, Orbital Engine Company, Perth, Western Australia, "Combustion and Emissions Characteristics of Orbital's Combustion Process Applied to Multi-Cylinder Automotive Direct Injected 4- Stroke Engines ", pages 1-12, well known.

The fuel supply to the injection valve 2 takes place at a fuel connection 15 of the injection valve 2, for example via a distributor 20 (fuel / air rail). In the distributor 20 , fuel is pumped from a fuel tank, not shown, via a fuel pump, not shown. The gaseous medium is supplied to the injection valve 2 at a medium connection 16 of the injection valve 2 , for example likewise via the distributor 20 . The gaseous medium is fed through a compressor, not shown, into the distributor 20 , which distributes the compressed medium to the individual inlet valves 2 .

The combustion chamber 7 is delimited by the piston 10 and the cylinder head 1 . For example, a single intake valve 3 of the internal combustion engine draws air from an intake pipe 22 into the combustion chamber 7 during the intake stroke. After the combustion, the exhaust gases are discharged into an exhaust pipe 23 via, for example, a single exhaust valve 4 . Of course, two or more intake valves 3 and two or more exhaust valves 4 per cylinder 8 can be provided.

The internal combustion engine can be a supercharged internal combustion engine, in which air is conveyed under pressure into the intake pipe 22 of the internal combustion engine. For example, an exhaust gas turbocharger can be used for this purpose.

According to the invention, the internal combustion engine has at least one additional injection valve 25 , which can deliver fuel into an intake area 26 of the internal combustion engine. The additive injection valve 25 may be 25 known design a conven nelles, for example electromagnetically actuated Never The pressure injector. The suction region 26 is formed from the inside of the suction pipe 22 , in which air and the fuel emitted by the additional injection valve 25 can flow into the combustion chamber 7 when the inlet valve 3 is open. The fuel is emitted from the additional injection valve 25, for example in the direction of the inlet valve 3 of the internal combustion engine. The Zusatzein injection valve 25 is, for example, downstream of a throttle valve 27 rotatably accommodated in the intake pipe 22 and is connected to the fuel supply 17 via its fuel, for example, also to the distributor 20 . It is possible to hen an additional injection valve 25 for each cylinder 8 of the internal combustion engine. These can be arranged directly in the inlet channels. This way of injection is well known to the person skilled in the art under the terms of multipoint injection. However, it is also possible to provide only a single additional injection valve 25 for all or at least for a number of cylinders 8 of a multi-cylinder internal combustion engine. The additional injection valve 25 gives the fuel upstream of a branching of the intake pipe 22 for the individual cylinder 8 in the still unbranched intake pipe 22 , which is then divided evenly into the branches on the individual cylinders 8 . This way of injection is well known to the person skilled in the art under the term single point injection.

The delivery of fuel by means of the additional injection valve 25 is additionally provided according to the invention for the delivery of the fuel-medium mixture by means of the injection valve 2 . The delivery of additional fuel with the additional injection valve 25 is provided essentially in the obe ren partial load range up to and including the full load of the internal combustion engine. The additional delivery of fuel can be carried out over the entire speed range of the internal combustion engine as soon as higher loads are demanded of the internal combustion engine. Via an electronic control unit 30 , the control of the fuel delivery of the additional injection valve 25 and the injection valve 2 can be carried out depending on the operating parameters of the internal combustion engine. However, provision is also made for the internal combustion engine to be operated on its own by dispensing fuel by means of the additional injection valve 25 . The injection valve 2 is no fuel-medium mixture at this time, with the result that the injection valve 2 is not flowed through by fuel and is cooled, so that there is a temperature increase on a blow valve 2 due to the ongoing combustion in the combustion chamber 7 is coming. The occasionally sole operation with the additional injection valve 25 enables a cleaning of the injection valve 2 from deposits, since coking or the like is burned off by the relatively high temperature at the injection valve 2 . The operation of the internal combustion engine with an exclusive fuel supply can be scheduled for predetermined cleaning intervals, regardless of the load range at hand.

Fig. 2 shows a section through an internal combustion engine according to a second embodiment according to the invention, in which all the same or equivalent parts are identified by the same reference numerals of the first embodiment shown in FIG. 1. In a modification of the first embodiment, the internal combustion engine does not have an injection valve 2 , but instead of the injection valve 2 is equipped with a direct injection valve 32 for direct petrol injection. The delivery of additional fuel by means of the additional injection valve 25 is hen in the same way as in the first embodiment. In the direct injection valve 32 , the fuel is dispensed at a relatively high pressure of about 70 bar or more in a direct manner in the form of a fuel cloud consisting of finest droplets into the combustion chamber 7 of the cylinder 8 of the internal combustion engine. The ignition of the fuel introduced into the combustion chamber 7 takes place in a known manner via the spark plug 6 . The ignition electrodes 12 of the spark plug are located in the immediate vicinity of an outer edge 14 of a cone jet 19 emitted by the direct injection valve 32 or partially in the cone jet 19 . The cone beam 19 can be a hollow cone beam or a full cone beam. The direct injection valve can be actuated electromagnetically or piezoelectrically. The structure and operation of such valves 32 is known to the person skilled in the art, for example from DE 195 48 526 A1. It is also possible, 32 not to be arranged in difference to the illustration in Fig. 2, the direct injection valve center, but in the lateral position so that lateral injection takes place in the combustion chamber 7. The spark plug is then, for example, in a central, in particular vertical position in the combustion chamber 7 .

When using a direct injection valve 32 , the medium end 16 according to FIG. 1 can be omitted, since such tiles only require a fuel connection 15 . In the same way as in the injection valve 2 described here, a common distributor 20 (common rail) can also be provided for supplying fuel to the individual direct injection valves 32 .

Fig. 3 shows a diagram of the power output of the internal combustion engine pme plotted against the speed n. Nmin represents the minimum speed and nmax the maximum speed of the internal combustion engine. The line I shows the course of the maximum possible power output of the internal combustion engine, when a fuel delivery can be achieved with only the injection valve 2 or with only the direct injection valve 32 . The line II shows the course of the maximum possible power output of the internal combustion engine, which is possible with the delivery of the fuel-medium mixture of the Einla seventils 2 or the direct injection valve 32 and with the additional intake manifold injection by means of the additional injection valve 25 . As the line II shows, with the additional injection of the additional injection valve 25, an increase in the output of the internal combustion engine which is essentially uniform over the rotational speed can be achieved.

With the fuel supply system according to the invention are available Operation of the internal combustion engine two principles to mix education available, namely on the one hand the inner ge formation of mixtures with direct fuel delivery into the combustion chamber and on the other hand the supply outside the combustion chamber prepared mixture using intake manifold injection. By Combination of the principles of mixture formation is in every Be drive range of the internal combustion engine an optimal mixture education feasible with regard to low pollutants missions and low fuel consumption. Here is ins especially in higher load ranges the additional mixture feed provided through the suction area. In the lower Internal mixture formation is preferred in load ranges, whereby by means of fuel metering during the compression stroke stratified mixture formation occurs. In stratified charge rubbed the internal combustion engine largely unthrottled and operated in a quality-controlled manner based on the amount of fuel be achieved with advantages in fuel consumption the.

Fig. 4 shows in a diagram with the fuel quantity pme plotted against the speed n of the internal combustion engine, an example of various operating modes of the internal combustion engine, in which internal mixture formation KHDE, SHDE and intake manifold injection SRE are combined in accordance with the load range. Stratified charge operation with internal mixture formation is provided in the idling range BM1 and in the low load range BM2 of the internal combustion engine. In stratified charge operation, a stratified mixture cloud with locally different fuel concentrations is formed in the combustion chamber. The mixture cloud is ignited in a local area with an ignitable mixture composition, as a result of which the internal combustion engine is operated as a whole with lean mixture formation and low fuel consumption.

In the middle load range BM3 is in addition to the inner Ge mixing formation the supply of lean homogeneous mixture provided the intake area of the internal combustion engine. The by SRE intake manifold injection using the additional injection valve formed mixture is in the combustion chamber by the di amount of fuel introduced to an ignitable level enriched. The direct delivery of fuel using Fuel injection or mixture injection takes place during during the compression cycle KHDE at a short distance the ignition timing. Because of that directly assigned to the combustion chamber nete valve, that is, the injection valve or the direct injection valve, so there is an ignition injection Amount of fuel for local mixture enrichment. To this Way is a very lean in the medium load range BM3 Combustion related to late ignition initiation possible. The mixture is further leaned by Charging achieved. With the combined mixture formation with Intake manifold injection SRE and internal mixture formation with Can deliver fuel during the compression stroke KHDE low nitrogen oxide emissions can be achieved, as with previous processes for internal mixture formation only with Ab gas recirculation were accessible. With the invention Fuel supply system can therefore due to the possible Reduction of the exhaust gas recirculation rate or waiving Ab gas recirculation Advantages in non-stationary operation of the Brenn  engine can be reached. Furthermore occurs in this Operating mode BM3 of the internal combustion engine with combined Mixture formation SRE + KHDE a reduction in the exhaust gas temperature structure, which increases the effectiveness of exhaust gas aftertreatment is significantly increased with lean combustion.

In the high-load area BM4, the mixture formation takes place via Intake manifold injection SRE and direct fuel delivery in the combustion chamber during the intake stroke SHDE, whereby in Combustion chamber homogeneous mixture is formed. It is possible at also, the homogeneous combustion chamber charge exclusively via Prepare intake manifold injection SRE.

The combination of intake manifold injection and internal Ge mixed education also permits in the event of a failure the direct injection valves in particular the operation of the engine in an emergency operating mode stored in the control unit. In order to is an additional one for reliable engine operation Given security.

Claims (16)

1. Fuel supply system for a spark ignition internal combustion engine, which has at least one in or on a cylinder head ( 1 ) arranged injection valve ( 2 ), the fuel and a gaseous medium is supplied under pressure to a fuel medium by means of the injection valve ( 2 ) -Delivery mixture directly into a combustion chamber ( 7 ) of the internal combustion engine, characterized in that at least one further injection valve ( 25 ) is provided in a suction area ( 26 ) of the internal combustion engine for additional fuel delivery, the injection valve ( 2 ) and the injection valve ( 25 ) are assigned to a common control unit in the suction area ( 26 ) and can be released in a coordinated manner. 2. Fuel supply system for a spark-ignition internal combustion engine, which has at least one in or on a cylinder head ( 1 ) arranged direct injection valve ( 32 ), the fuel is supplied under pressure to direct fuel by means of the direct injection valve ( 32 ) directly into a combustion chamber ( 7 ) from the internal combustion engine, characterized in that at least one further injection valve ( 25 ) is provided in an intake area ( 26 ) of the internal combustion engine for additional fuel delivery, the direct injection valve ( 32 ) and the injection valve ( 25 ) in the intake area ( 26 ) are assigned to a common control unit and can be released to one another in a coordinated manner. 3. Fuel supply system according to claim 1 or 2, characterized in that it is a supercharged internal combustion engine, in which air is conveyed under pressure into the suction area ( 26 ) of the internal combustion engine. 4. Fuel supply system according to claim 1 or 2, characterized in that for each cylinder ( 8 ) of the internal combustion engine, an injection valve ( 25 ) is hen vorgese (multipoint injection). 5. Fuel supply system according to claim 1 or 2, characterized in that a common injection valve ( 25 ) is provided for all cylinders ( 8 ) of the internal combustion engine (single-point injection). 6. Fuel supply system according to claim 1 or 2, characterized in that the suction region ( 26 ) from the inside of an intake pipe ( 22 ) is formed. 7. The method for operating a spark-ignition internal combustion engine with a fuel supply system according to claim 1 or 2, characterized in that the control unit ( 30 ) the combustion chamber ( 7 ) associated valve ( 2 , 32 ) and the additional injection valve ( 25 ) in the intake area ( 26 ) controls depending on the operating range of the internal combustion engine and determines their respective throughput. 8. The method according to claim 7, characterized in that the delivery of fuel by means of the injection valve ( 25 ) is provided in the entire load range of the internal combustion engine and the combustion chamber ( 7 ) additional fuel mixture (SRE) is supplied via the intake area ( 26 ). 9. The method according to claim 7, characterized in that the delivery of fuel by means of the injection valve ( 25 ) and the additional mixture supply (SRE) via the suction area ( 26 ) to the combustion chamber ( 7 ) is provided substantially in higher load areas of the internal combustion engine. 10. The method according to claim 8 or 9, characterized by a stratified charge operation of the internal combustion engine in the idle range and in lower to medium load ranges, wherein the combustion chamber ( 7 ) associated valve ( 2 , 32 ) for direct fuel entry (KHDE) in the combustion chamber ( 7 ) is opened during the compression stroke of the respective cylinder ( 8 ). 11. The method according to claim 10, characterized in that in the idling range and in the lower load ranges, the mixture formation takes place predominantly or exclusively via direct metering in the combustion chamber ( 7 ) during the compression stroke. 12. The method according to claim 10 or 11, characterized in that a lean fuel mixture is supplied via the intake area ( 26 ) in medium load ranges and a layered, ignitable mixture is formed by direct metering (KHDE) during the compression stroke in the combustion chamber. 13. The method according to any one of claims 7 to 12, characterized in that in higher load ranges, a direct fuel input (SHDE) into the combustion chamber ( 7 ) takes place during the intake stroke of the respective cylinder ( 8 ). 14. The method according to claim 13, characterized in that in higher load ranges of the internal combustion engine up to full load direct fuel input (SHDE) and additional fuel supply (SRE) via the intake area ( 26 ) is provided. 15. The method according to any one of claims 7 to 12, characterized in that in higher load ranges and at full load of the internal combustion engine, the combustion chamber ( 7 ) is supplied exclusively from the injection valve ( 25 ) into the suction area ( 26 ). 16. The method according to any one of claims 7 to 15, characterized in that the internal combustion engine may be operated for a cleaning interval irrespective of the load range with exclusive fuel supply (SRE) via the suction region ( 26 ) by means of fuel delivery through the additional injection valve ( 25 ).