In-cylinder injection gasoline engine

Details In-cylinder injection gasoline engine In-cylinder injection gasoline engine

2001-11-26

2002-12-31

Solis, Erick (Department: 3747)

Internal-combustion engines

Combustion chamber means having fuel injection only

Combustible mixture stratification means

C123S305000, C123S298000, C123S302000

Reexamination Certificate

active

06499457

ABSTRACT:

BACKGROUND OF INVENTION
This invention relates to an in-cylinder injection gasoline engine and more particularly to a combustion chamber arrangement for such engines.
It has been proposed to employ direct cylinder injection to improve the performance and particularly the fuel economy and exhaust emission control of internal combustion engines. By utilizing direct cylinder injection, it is possible to obtain stratification under some running conditions to allow the engine to run on a leaner than stoichiometric mixture. In this way it is not necessary to provide a homogeneous stoichiometric mixture in the entire combustion chamber to initiate combustion and to develop the required power.
To accomplish this in an open chamber, the fuel injector must inject fuel in a way to form a fuel patch that will be present at the spark gap at the time it is fired. Although this can be easily accomplished if a pre-chamber is employed, it is difficult to achieve this result in an “open chamber”. Open chambers are preferred for a variety of reasons including the pumping losses generated by the pre-chamber.
FIGS. 1 and 2
illustrate a typical type of approach that attempts to produce this result in an open chamber.
FIG. 1
is a top plan view of a piston used in the arrangement and the associated fuel injector as mounted in the cylinder head.
FIG. 2
is a cross sectional view taken along the line
2
—
2
of FIG.
1
. As seen in these figures, a piston, indicated generally by the reference numeral
11
reciprocates in a cylinder bore, indicated by the reference numeral
12
. The piston
11
, cylinder bore
12
and an associated cylinder head surface
13
define the combustion chamber.
The head of the piston
11
is formed with a dome comprised of a pair of angularly related, inclined surfaces
14
and
15
which join a generally flat upper surface
16
. A bowl or recess
17
is formed in the piston head and extends through the inclined surface
15
and the. upper flat surface
16
. This bowl
17
has a generally curved configuration which extends upwardly and terminates at its inner peripheral edge adjacent a spark plug
18
. The spark plug
18
positioned generally on the axis of the cylinder bore
12
.
A fuel injector
19
is mounted in the cylinder head surface
13
or cylinder block at one side of the cylinder bore
12
. This fuel injector
19
sprays fuel toward and into the piston bowl
17
. In addition, a swirl is generated in the combustion chamber as indicated by the arrows A. This swirl is generated by the induction system so as to sweep the injected fuel in a path indicated by the arrow B in the bowl
17
and toward the gap of the spark plug
18
. In addition, the inclined surface
14
forms a squish area that drives the air in the direction indicated by the arrows D in FIG.
2
. so as to prevent the fuel from escaping from the bowl
17
beyond the outer periphery of the area bounded by the spark plug
18
.
An engine of this type may also be provided with a variable valve timing mechanism for varying the valve timing and/or degree of opening of the valves. Thus, the configuration of the combustion chamber and particularly the head surface of the piston
11
must be such as to afford clearance between the valve heads and the piston surfaces under all timing and lift conditions. This results in the formation of a lower than desired compression ratio.
Also, under off idle loads there may be fuel left deposited on the piston bowl
17
after combustion has completed. This increases the problem of hydrocarbon emissions. Furthermore, even though the spark plug
18
is positioned at the center of the combustion chamber, there is a likelihood that fuel may pass beyond the bowl
17
toward the opposite side of the combustion chamber regardless of the swish action indicated by the arrows D. Thus there can be further unburned fuel in the combustion chamber.
Furthermore these conditions increase the likelihood of knocking, even though a low compression ratio has been dictated by the bowl configuration.
It is, therefore, a principle object to this invention to provide an improved combustion chamber for a direct injected internal combustion engine wherein the compression ratio may be significantly raised without causing problems in clearance for the valves and while insuring rapid flame propagation and complete combustion under all running conditions.
It is a further object to this invention to provide an improved high efficiency combustion chamber, fuel injection and ignition arrangement for direct injected engines.
SUMMARY OF INVENTION
This invention is adapted to be embodied in an internal combustion engine that is comprised of an engine body that defines at least one cylinder bore that is closed at one end by a cylinder head surface and at the other end by the head of a piston that reciprocates in the cylinder bore. A fuel injector is mounted in the engine body contiguous to the axis of the cylinder bore. The fuel injector is configured to spray fuel downwardly toward the piston head and in at least two circumferentially spaced, fuel injection directions. The piston head is formed with a cavity arrangement having at least two circumferentially spaced, concave curved wall portions that curve upwardly toward the cylinder head at their radially outer extent. The circumferential spacing at the fuel injection directions correspond to the circumferential spacing of the piston concave curved wall portions so that fuel sprayed from the fuel injector is directed toward the piston concave curved wall portions. A pair of circumferentially spaced ignition devices are provided in the cylinder head surface in proximity to the upper ends of the piston concave curved wall portions for igniting the fuel sprayed from the fuel injector.


REFERENCES:
patent: 5329901 (1994-07-01), Onishi
patent: 6035824 (2000-03-01), Lee
patent: 6267107 (2001-07-01), Ward

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