Internal combustion engine

Details Internal combustion engine Internal combustion engine

2002-06-25

2004-09-07

Argenbright, Tony M. (Department: 3747)

Internal-combustion engines

Transmission mechanism from piston

Reexamination Certificate

active

06786189

ABSTRACT:

BACKGROUND OF THE INVENTION
CROSS-REFERENCES TO RELATED APPLICATIONS
This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2001-205174 filed in Japan on Jul. 5, 2001, and Patent Application No. 2001-205175 filed in Japan on Jul. 5, 2001, the entirety of each of which are herein incorporated by reference.
1. Field of the Invention
The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine in which a piston slidably fitted in a cylinder is connected to a crankshaft through a connecting rod. The present invention specifically relates to a horizontally-opposed type internal combustion engine in which left and right pistons are slidably supported in left and right cylinder banks horizontally opposed to each other. A crankshaft is positioned between the pistons and is connected to the pistons through connecting rods.
2. Description of the Background Art
A horizontally-opposed type internal combustion engine has been known in the background art, e.g., as seen by the exemplary engine described in Japanese Patent Laid-open No. 2000-110661. The engine described in Japanese Patent Laid-open No. 2000-110661 has a structure in which left and right cylinders are disposed on both sides of a crankshaft. Pistons slidably fitted in the cylinders are each connected to the crankshaft through a connecting rod. A combustion chamber of each of the cylinders is provided at an end portions of the cylinders on the opposite side of the crankshaft. Therefore, each of the pistons is moved in the direction of approaching the crankshaft during an expansion stroke.
FIG. 7
is a schematic view of a general 4-cycle single-cylinder internal combustion engine according to the background art. The internal combustion engine E includes a cylinder
01
, a piston
02
slidably fitted in the cylinder
01
, a cylinder head
03
connected to the cylinder
01
, a combustion chamber
04
provided between a lower surface of the cylinder head
03
and the cylinder
01
, a crankshaft
05
, and a connecting rod
06
for connecting the piston
02
to the crankshaft
05
. The piston
02
is located at a position between the cylinder head
03
and the crankshaft
05
.
FIG.
7
(
a
) shows a condition where the piston
02
is located at a position of top dead center, e.g., when the crank angle &thgr; is 0°. FIG.
7
(
c
) shows a condition where the piston
02
is located at a position of bottom dead center, e.g., when the crank angle &thgr; is 180° (Position C in FIGS.
7
(
a
)-(
c
). FIG.
7
(
b
) shows a condition where the piston
02
is located at a middle position (Position B in FIGS.
7
(
a
)-(
c
) between top dead center (Position A in FIGS.
7
(
a
)-(
c
)) and bottom dead center (Position C), e.g., when the crank angle &thgr; is not 90° but is an angle &thgr;a less than 90°. While the connecting rod
06
is on the axis L
1
of the cylinder
01
at top dead center and bottom dead center, the connecting rod
06
is inclined by an angle &phgr; relative to the axis L
1
of the cylinder
01
at the middle position.
In
FIG. 6
, the relationship between the crank angle &thgr; with reference to top dead center of the internal combustion engine E and the displacement x of the piston
02
with reference to top dead center is indicated by a chain line. The stroke between top dead center and bottom dead center of the piston
02
is 2R (R is the crank radius). As has been described with reference to FIG.
7
(
b
), when the piston
02
is located at the middle position, e.g., any intermediate point between, between top dead center and bottom dead center, e.g., at a point where the displacement x of the piston
02
is R, the crank angle &thgr; is an angle &thgr;a which is less than 90°. In contrast, in a sine curve (x=Rsin(&thgr;−90°)+R) indicated by a solid line, the crank angle &thgr; is 90° when the piston
02
is located at the middle position between top dead center and bottom dead center.
Accordingly, in the case of the internal combustion engine E of the background art, the line (see the chain line) representing the relationship of the displacement x of the piston
02
to the crank angle &thgr; is located on the upper side relative to the sine curve indicated by the solid line. When the piston
02
is lowered from top dead center in the beginning stage of the expansion stroke, the increase of the displacement x of the piston
02
with reference to the increase of the crank angle &thgr; is greater when compared with the characteristics of the sine curve.
The present inventors have identified the following problems associated with the background art. In the internal combustion engine E of the background art shown in
FIG. 7
, the crankshaft
05
is disposed on the lower side of the direction of the axis L
1
of the cylinder
01
. Therefore, the engine E, and the mass dispersed in the direction of the axis L
1
, is enlarged in size in the direction of the axis L
1
.
In addition, in order to enhance thermal efficiency of an internal combustion engine E, it is desirable to enhance the degree of an equal volume of a mixture gas at the time of combustion. The volume of the combustion chamber
04
on the upper side of the piston
02
is increased when the combustion of the mixture gas is started in the vicinity of top dead center of the piston
02
and the piston
02
is lowered. Accordingly, the equal volume is higher and thermal efficiency is higher as the increase of the volume of the combustion chamber
04
with reference to the increase of the crank angle &thgr; is smaller. However, in the case of the internal combustion engine E of the background art, the increase of the volume of the combustion chamber
04
with reference to the increase of the crank angle &thgr; from top dead center is enlarged and the equal volume degree is lowered. This arrangement is disadvantageous for enhancing the thermal efficiency of the internal combustion engine E.
The horizontal opposed type internal combustion engine described in Japanese Patent Laid-open No. 2000-110661 also suffers from the above-mentioned problems because it employs a structure in which the general single-cylinder internal combustion engines according to the prior art simply combine a pair of pistons opposed to each other.
Further, the horizontal opposed type internal combustion engine described in Japanese Patent Laid-open No. 2000-110661 requires complicated structures for the intake system and the valve mechanism, because the left and right cylinder heads are located away from each other.
SUMMARY OF THE INVENTION
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
An object of the present invention is to reduce the size of an internal combustion engine in the axial direction of the cylinder.
An object of the present invention is to enhance the equal volume degree at the time of combustion of a mixture gas of the internal combustion engine and to enhance thermal efficiency.
An additional object of the present invention is to provide the aforementioned improvements and advantages for a horizontally opposed type internal combustion engine. Specifically, an object of the present invention is to enhance the equal volume degree at the time of combustion of a mixture gas in a horizontal opposed type internal combustion engine, enhance thermal efficiency thereof, and to simplify the structures of the associated intake system and valve mechanism.
One or more of these and other objects are accomplished by an internal combustion engine comprising a cylinder; a cylinder head; a piston slidably fitted in the cylinder; an auxiliary cylinder coaxial with the cylinder; an auxiliary piston slidably fitted in the auxiliary cylinder; a first connecting rod integrating the piston and the auxiliary piston into a single unitary body; a combustion chamber provided in the cylinder head; a pair of left and right crankshaft halves; and a pair of second connecting rods connecting the auxi

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