Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-05-18
2001-11-20
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C073S114220
Reexamination Certificate
active
06318342
ABSTRACT:
BACKGROUND INFORMATION
The present invention relates to a fuel injector-pressure sensor combination for fuel injection systems for direct injection of fuel into the combustion chamber of an internal combustion engine and for measurement of the pressure in the combustion chamber.
A fuel injector having a piezoelectric actuator is known, for example, from German Published Patent Application No 195 00 706. In this known fuel injector, the piezoelectric or magnetostrictive actuator activates a power piston which acts upon a reciprocating piston via a hydraulic path transformer. The reciprocating piston has a positive connection with a valve closer provided at the injection opening via a valve needle. The piezoelectric or magnetostrictive actuator therefore has a non-positive connection to the valve closer via the hydraulic path transformer. If an appropriate electrical voltage is applied to the actuator, it expands and displaces the power piston correspondingly. Even a relatively slight displacement of the power piston is transformed by the hydraulic path transformer into a considerably greater displacement of the reciprocating piston so that the valve closer clears the injection opening, leaving it with an adequate cross-section.
A fuel injector of similar design is derived from German Patent No 43 06 073. A housing-side support of the actuator in a special spherical disk bearing in particular is known from this printed publication in order to cause the piezoelectric actuator to have complete contact with the plunger it is to act on if the actuator end surfaces are slightly non-parallel.
For various applications, it is desirable to detect the pressure prevailing in the combustion chamber via a suitable sensor. For this purpose, it has heretofore been customary to provide pressure sensors in the cylinder head of the internal combustion engine as individual components and to measure the combustion pressure in the combustion chambers of the engine in this manner. Since present-day internal combustion engines have multiple intake and exhaust valves per combustion chamber and also in the case of direct injection, a spark plug to ignite the fuel is also necessary in the combustion chamber of an internal combustion engine having spark ignition in addition to a fuel injector for direct injection of the fuel into the combustion chamber, the available installation space on the cylinder head is very limited. Since a separate bore in the cylinder head is required for each pressure sensor designed as individual components, the practical implementation of pressure measurement in injection systems with direct injection into the combustion chamber is difficult.
SUMMARY OF THE INVENTION
In contrast, the fuel injector-pressure sensor combination according to the present invention has the advantage that the fuel injection and pressure measurement are accomplished with one component that implements these functions jointly. At the same time, only one single cylinder bore is required to install the fuel injector-pressure sensor combination and not, as in previous devices, one cylinder bore for the fuel injector and one additional cylinder bore for the pressure sensor. Moreover, the fact that the pressure sensors are not required as an additional component makes a distinct reduction of production costs possible.
The method for operating a fuel injector-pressure sensor combination has the advantage that the fuel injector is activated and the pressure is detected by a single piezoelectric or magnetostrictive element that fulfills both of these functions. Since the metering of fuel and the detection of combustion pressure do not take place simultaneously but rather in staggered operating phases, the fuel can be metered and the combustion pressure measured with the same components in succession.
In an advantageous manner, each cylinder of the internal combustion engine may be checked for the presence of knock due, for example, to the presence of leaking valves or misfiring due, for example, to a defective spark plug. This can be converted into a warning signal for the driver of a motor vehicle in which the internal combustion engine equipped with the fuel injector-pressure sensor combination according to the present invention is installed.
REFERENCES:
patent: 3194162 (1965-07-01), Williams
patent: 3589345 (1971-06-01), Benson
patent: 4502438 (1985-03-01), Yasuhara
patent: 4798188 (1989-01-01), Ito et al.
patent: 5111699 (1992-05-01), Walstra et al.
patent: 5127378 (1992-07-01), Ito
patent: 5479902 (1996-01-01), Wirbeleit
patent: 6148842 (2000-11-01), Kappel et al.
patent: 6155212 (2000-12-01), McAlister
patent: 31 30 238 (1983-02-01), None
patent: 43 06 073 (1994-06-01), None
patent: 195 00 706 (1996-07-01), None
patent: 196 22 651 (1996-12-01), None
patent: 2 145 153 (1985-03-01), None
Krebs Holger
Simon Stefan
Kenyon & Kenyon
Miller Carl S.
Robert & Bosch GmbH
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