Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Patent
1997-05-14
1998-04-14
Miller, Carl S.
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
123456, F02B 7700, F02M 4100
Patent
active
057380635
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a method, known from U.S. Pat. No. 5,197,438, for operating a fuel injection system in which the fuel is fed in a measurable quantity at high pressure into a high-pressure reservoir, whose pressure is controlled by a pressure control valve and from which fuel is drawn for injection via electrically controlled injection valves. In the fuel injection system operated in the known way, it can happen that the high-pressure fuel storage system springs a leak, which is especially critical in view of the high injection pressures for injecting fuel in internal combustion engines with externally supplied ignition.
ADVANTAGES OF THE INVENTION
With the method according to the invention for operating a fuel injection system of this generic type, it is now possible to ascertain automatically and exactly when such a known high-pressure system springs a leak, especially in the region of the high-pressure reservoir. If a leak occurs, a warning can advantageously be given, or a suitable intervention into the fuel injection system can advantageously be made in order to avoid further damage.
Especially advantageously, the quantity of outflowing fuel required to regulate the fuel pressure in the high-pressure reservoir is detected by means of a measuring instrument. For a known delivery of fuel brought to high pressure into the high-pressure fuel reservoir, and with a known fuel injection quantity via the injection valves, one obtains an exact balance of delivered and removed fuel, which indicates a deviation between the delivered and removed fuel only whenever there is a leak in the high-pressure reservoir. The quantity fed, which results from the drive rpm of the fuel pump and its constant feed quantity per revolution of the drive shaft, can advantageously easily be detected by means of a control unit, and the necessary signals for controlling the injection valves, which correspond to the injected fuel quantity, are already available.
In an advantageous further feature, a fuel injection system for performing the method is disclosed.
BRIEF DESCRIPTION OF THE DRAWING
An exemplary embodiment of the invention is shown in the drawing and will be described in further detail in the ensuing description.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
In the drawing, a high-pressure fuel reservoir 1 is .shown, which is supplied with fuel, which is brought to high injection pressure, via a supply line 2 from a fuel pump 3 that aspirates fuel from a fuel container 4. Pressures that are substantially above 1000 bar occur in the process. The pressure in the high-pressure fuel reservoir is detected by a pressure transducer 6, whose signal is delivered to a control unit 7, by which, if a fixedly set or desired pressure, which may be dependent on a particular operating state of the associated internal combustion engine, is exceeded, a pressure control valve 9 is triggered by a corresponding signal. This valve is located in a fuel return line 10 from the high-pressure fuel reservoir to the fuel container 4. From the high-pressure fuel reservoir, pressure lines 11 also lead away, each communicating with one fuel injection valve 14, by way of which valve at the appropriate time, a desired quantity of fuel can be injected to the engine. The control of the fuel injection quantity in terms of timing and amount is also effected via the control unit 7, which for purposes of this control receives control signals corresponding to the rpm and the load at which the associated engine is intended to be operated. The control of this fuel injection quantity is effected for instance in a known manner by means of magnet valves, which control the communication between the high-pressure reservoir and the injection valve. Any fuel control quantities that might occur and are capable of flowing back into the tank are likewise returned to the tank via the return line 10.
The fuel pump is for instance driven synchronously with the engine operated by the fuel injection system, or in other words is driven at an rpm that is alread
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Burkel Rainer
Eyberg Wilhelm
Pfuhl Berthold
Greigg Edwin E.
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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