Combustion chamber for direct injection engine

Details Combustion chamber for direct injection engine Combustion chamber for direct injection engine

2001-09-21

2003-01-21

Mohanty, Bibhu (Department: 3747)

Internal-combustion engines

Combustion chamber means having fuel injection only

Combustible mixture stratification means

C123S298000, C123S305000

Reexamination Certificate

active

06508226

ABSTRACT:

BACKGROUND OF INVENTION
This invention relates to an internal combustion engine and particularly one of the type having direct cylinder injection and more particularly to a combustion chamber for such an engine.
In the interest of improving engine performance in the field of power, fuel consumption and exhaust emission control, it has been proposed to employ direct cylinder injection. By injecting fuel directly into the combustion chamber, it is not necessary to achieve a homogeneous mixture in the combustion chamber under all running conditions so as to insure combustion. In other words, if direct cylinder injection is possible, stratification can be obtained.
One problem in connection with obtaining a stratified charge and good combustion under low speeds and low loads is the difficulty in insuring that a stoichiometric mixture is present at the spark plug at the time of ignition. Various combustion chamber arrangements have been proposed with an effort to achieve this. Many of theses combustion chamber designs employ a bowl that is formed in the head of the piston and which is configured so as to enable stratification at least under some running conditions.
For example,
FIG. 1
is a prior art cross sectional view taken through the cylinder of one type of engine that has been proposed to achieve this goal. This is a combustion chamber of the type that is disclosed in Japanese Published Application Hei 6-81651, published Mar. 22, 1994In this engine, there is a combustion chamber S which is formed by a cylinder bore
11
of a cylinder block
12
, a lower surface
13
of a cylinder head
14
which, in that construction, is detachably connected to the cylinder bloc k
12
and a piston
15
that reciprocates in the cylinder bore
14
. In this combustion chamber S, the piston has its head portion formed with a pair of angularly inclined upper surfaces
16
and
17
which face diametrically opposed portions of the cylinder head lower surface
13
and in which respective intake
18
and exhaust passages
19
are formed. Intake and exhaust valves
21
and
22
cooperate with the valve seats formed at the ports of these intake and exhaust passages
18
and
19
to control the flow of air into the combustion chamber and exhaust gases out of the combustion chamber.
The piston head inclined portion
16
is formed with a bowl like recess
23
, which is formed primarily on the intake side of the piston head but extends slightly over toward the exhaust side.
A spark plug
24
is mounted in the cylinder head
14
generally on the center of the combustion chamber S and the axis of the cylinder bore
11
.
A fuel injector
25
is mounted on the intake side of the cylinder head
14
and sprays its fuel in a pattern as shown in this figure so as to impinge upon the cylinder head recess
23
. The intake port or ports
18
are configured so as to cooperate with the bowl
23
to generate a tumble action as shown by the arrow “a” in this figure. The theory is that this will cause the fuel deposited in the piston head bowl
23
to be swept toward the spark plug
24
to insure stratification under low speed and low load conditions.
There are several disadvantages with this type of combustion chamber. Because of the fact that the fuel is injected on the surface of the piston head bowl
23
it tends to become excessively rich and results in lack of complete fuel evaporation into the combustion chamber S. This is because more fuel is deposited than can effectively vaporize and is liable to cause smoke generation and unwanted exhaust gas emissions.
Another solution to the problem of combustion chamber configuration and for direct injected engines is shown in Japanese Published Application Hei 11-324680, and its issued United States Letters Patent counterpart 6,062,195, issued May 16, 2000. This type of arrangement is shown in FIG.
2
and again has a combustion chamber S that is formed by a piston
31
that reciprocates in a cylinder bore
32
of a cylinder block
33
. This cooperates with a combustion chamber recess formed in a cylinder head
34
that is affixed to the cylinder block
33
in a suitable manner.
Intake passages
35
open into the combustion chamber S and are valved by intake valves
36
positioned on one side of the cylinder head. On the other side of the cylinder head, exhaust passages
37
are formed which are valved by exhaust valves
38
.
A fuel injector
39
is mounted between the intake valves
36
and below them and injects fuel into the combustion chamber S which is formed by the head of the piston
31
, which has a slight concave configuration
41
although it is substantially flat. The fuel injector
39
sprays its fuel across this slightly concave surface
41
and propagates towards the exhaust valve
38
so as to be heated and improve fuel vaporization.
In this arrangement, there is a fairly large angle &agr; between the stems of the intake and exhaust valves
36
and
38
so that the exhaust valve will be inclined to receive the fuel and also so as to preclude the fuel from passing out of the exhaust valve. Thus, this configuration causes a fairly large volume for the combustion chamber S at top dead center and makes it difficult to raise the compression ratio.
It is, therefore, a principal object to this invention to provide an improved combustion chamber configuration for a direct injected internal combustion engine.
It is a further object to this invention to provide an improved combustion chamber configuration permits the attainment of high compression ratios and avoids the likelihood of fuel condensing in the combustion chamber recess of the piston and not being able to evaporate fully before the spark plug is fired. Thus, the likelihood of smoke in the exhaust and unwanted hydrocarbons can be substantially reduced.
SUMMARY OF INVENTION
This invention is adapted to be embodied in an internal combustion chamber. The combustion chamber is defined by a cylinder bore closed at one end by a cylinder head combustion chamber surface and at the other end by a piston reciprocating in the cylinder bore. The cylinder head combustion chamber surface has a pair of angular related surface portions formed on diametrically opposed sides thereof. At least one intake port is formed in one of the cylinder head combustion chamber angularly related surface portions. At least one exhaust port is formed in the other of the cylinder head combustion chamber angularly related surface portions. The piston has a head portion with an upper combustion chamber surface. The piston head portion includes an inclined surface facing the one of the cylinder head combustion chamber surface portions and which is inclined toward the other of the cylinder head combustion chamber angularly related surface portions. A fuel injector is mounted in the engine on the side of the combustion chamber formed by the one of the cylinder head combustion chamber angularly related surface portions and sprays toward the piston head portion inclined surface such that at least a part of the fuel injected therefrom will be directed toward the exhaust port.


REFERENCES:
patent: 5921215 (1999-07-01), Wirth et al.
patent: 6062195 (2000-05-01), Tanaka et al.
patent: 6095114 (2000-08-01), Horie et al.
patent: 6244244 (2001-06-01), Fuwa et al.
patent: 6235042 (2001-12-01), Grigo et al.
patent: 6366437 (2002-01-01), Baika et al.
patent: 6-81651 (1994-03-01), None
patent: 11-324680 (1999-11-01), None

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