Internal-combustion engines – Combustion chamber means combined with air-fuel mixture... – Having a single combustible mixture inlet combined with...
Reexamination Certificate
2000-03-10
2001-11-13
Kwon, John (Department: 3747)
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
Having a single combustible mixture inlet combined with...
C123S430000
Reexamination Certificate
active
06314940
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a fuel feed system for a spark-ignition internal combustion engine including a direct fuel injection valve mounted on a cylinder head for injecting fuel and to a method of operating an internal combustion engine with such a fuel feed system.
The prior art already includes a fuel feed system (EP 0 308 467B1) which has a common rail which is attached to a cylinder head and which carries both fuel and air under pressure to blow-in valves accommodated in the cylinder head. For this purpose, corresponding fuel lines and air lines to the blow-in valves are provided in the common rail. Each blow-in valve has an electromagnetically actuable fuel injection valve of conventional construction which can discharge fuel into a mixture formation chamber provided within the blow-in valve. The fuel in the mixture formation chamber is then prepared with compressed air and partially vaporized in the mixture formation chamber. The fuel prepared in this way passes on into a discharge zone of the blow-in valve which has an electromagnetically actuable valve. In an open position of a valve-closing body of the electromagnetically actuable valve of the discharge zone, the fuel/air mixture in the mixture formation chamber is then blown out directly into the combustion chamber from an outlet opening of the blow-in valve at a relatively low pressure of, for example, 7 to 8 bar. The common rail is provided for supplying the blow-in valves with both fuel and air.
However, if large injection quantities are demanded from the known fuel feed system or from the blow-in valve, as is the case, for example, with high engine loads, there may be problems with the quality of mixture preparation since there is only a certain maximum quantity of fuel that the blow-in valve can prepare well. The same problems are also encountered with a fuel feed system which has direct-injection valves for direct petrol injection. Direct-injection valves discharge the fuel directly at a relatively high pressure in the form of a cloud of fuel comprising extremely fine droplets into a combustion chamber of the internal combustion engine. If relatively large quantities of fuel are demanded, however, the fuel discharged by the direct-injection valve is not fully prepared and use of the air in the combustion chamber is not optimal. Complete preparation of the fuel/air mixture discharged by the blow-in valve cannot be achieved with blow-in valves either. All this means that wetting of the internal walls of the cylinder and of the piston surface with fuel can occur. However, this kind of thing leads to incomplete combustion of the fuel in the combustion chamber, leading to a rise in noxious components in the exhaust gas. Particularly affected by this are internal combustion engines which have pressure charging of the intake air, by means of an exhaust turbocharger for example, since, in relation to the cylinder volume, these internal combustion engines require relatively large quantities of injected fuel.
It is the object of the invention to provide a fuel feed system with which an optimum mixture preparation as regards consumption and exhaust emissions takes place in the internal combustion engine in all operating ranges.
SUMMARY OF THE INVENTION
In a fuel feed system for a spark-ignition internal combustion engine, which system has at least a first injection valve, which is arranged in or on a cylinder head and to which fuel is fed under pressure for discharging directly into a combustion chamber of the internal combustion engine, at least on further injection valve is provided in an engine intake passage to discharge in certain operating ranges of the internal combustion engine, fuel into the intake passage of the internal combustion engine in addition to the discharge of the fuel of the first injection valve into the cylinder, and the first injection valve is designed for fuel injection volume lower than that required for full power operation of the engine.
The fuel feed system according to the invention for a spark-ignition internal combustion engine according to the invention has the advantage that the internal combustion engine can provide high power outputs over the entire engine-speed range without a significant increase in the proportion of noxious components in the exhaust gas.
The fuel injection system according to the invention offers the possibility of feeding in the fuel required for mixture formation not only by direct discharge into the combustion chamber by means of the blow-in valve, as in one configuration, or by means of direct injection, as in the other embodiment provided, but also via the air intake passage of the internal combustion engine. In this arrangement, a control unit controls the valve associated with the combustion chamber (blow-in valve or direct-injection valve) and the additional injection valve in the intake passage as a function of the operating range of the internal combustion engine and determines their respective flow rates. It is particularly expedient here if the additional fuel supply via the intake passage is provided essentially in the higher load range of the internal combustion engine. Thanks to the upstream fuel supplied into the intake passage, the valve provided for direct fuel discharge into the combustion chamber can be [constructed with] designed for an advantageous minimum/maximum quantity ratio (spread) since the quantity of fuel to be discharge per operating cycle can be fed in along two paths. In this arrangement, a lowering of the fuel pressure in the case of exclusively direct discharge into the combustion chamber, which is detrimental particularly in the low-load range, is prevented, thus improving mixture formation particularly in the important low-load range. At the same time, the fuel feed system components required for feeding fuel directly into the combustion chamber can advantageously be designed for lower total mass flow rates at full load than was hitherto the case with exclusively direct injection of blowing in. This also reduces the lost power in the fuel pump and, in the case of pressure-charged internal combustion engines, in the compressor and therefore leads to a reduction in fuel consumption. In the fuel feed system according to the invention with a blow-in valve in the cylinder head, the air assisted fuel injection system can additionally be designed for elevated blow-in pressures (at least 10 bar), thereby allowing a wider choice for the blow-in instant.
It is particularly advantageous that, when the internal combustion engine is at time operated exclusively with the additional injection valve, an increase in temperature can be achieved at the blow-in valves or the direct-injection valves, since this valve is then no longer cooled by the fuel during such discharge-free time, with the result that any deposits which may be present are then broken down by the rise in temperature which occurs at the blow-in valves or direct-injection valves.
Advantageous embodiments of the fuel feed system, for a spark ignition internal combustion engine will be described below in greater on the basis of the drawings:
REFERENCES:
patent: 3924598 (1975-12-01), Davis
patent: 4031867 (1977-06-01), Yasuda et al.
patent: 5081969 (1992-01-01), Long, III
patent: 5113829 (1992-05-01), Motoyama
patent: 5251582 (1993-10-01), Mochizuki
patent: 5291865 (1994-03-01), Sasaki
patent: 5357925 (1994-10-01), Sasaki
patent: 5875743 (1999-03-01), Dickey
patent: 6032640 (2000-03-01), Evans
patent: 195 48 526 A1 (1997-07-01), None
patent: 0 308 467 A (1989-03-01), None
patent: 308 467 B1 (1993-12-01), None
patent: 0 849 455 A2 (1998-06-01), None
patent: 56-151213 (1981-11-01), None
SAE Paper 98P-136, 1998 Rodney Houston—Combustion And Emissions Characteristics of Orbital's Combustion Process Applied to Multi-Cylinder Automotive Direct Injected 4-Stroke Engines.
Frey Juergen
Karl Guenter
Kraemer Stephan
Bach Klaus J.
Daimler-Chrysler AG
Kwon John
LandOfFree
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