U.S. patent application number 13/483217 was filed with the patent office on 2012-12-06 for port of internal combustion engine.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Kazuyoshi ABE.
Application Number | 20120304950 13/483217 |
Document ID | / |
Family ID | 47173520 |
Filed Date | 2012-12-06 |
United States Patent
Application |
20120304950 |
Kind Code |
A1 |
ABE; Kazuyoshi |
December 6, 2012 |
PORT OF INTERNAL COMBUSTION ENGINE
Abstract
A port that communicates an inside of a combustion chamber of an
internal combustion engine with an outside of the combustion
chamber includes a throat portion that has at least a portion of a
truncated cone shape, a valve seat portion that is connected to one
end portion of the throat portion to communicate the throat portion
with the inside of the combustion chamber, and a passage portion
that is connected to the other end portion of the throat portion to
communicate the throat portion with the outside of the combustion
chamber.
Inventors: |
ABE; Kazuyoshi; (Susono-shi,
JP) |
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi
JP
|
Family ID: |
47173520 |
Appl. No.: |
13/483217 |
Filed: |
May 30, 2012 |
Current U.S.
Class: |
123/188.1 |
Current CPC
Class: |
F01L 2001/0537 20130101;
F01L 3/22 20130101; F02B 31/00 20130101; Y02T 10/12 20130101; Y02T
10/146 20130101; F01L 1/46 20130101; F01L 2303/00 20200501 |
Class at
Publication: |
123/188.1 |
International
Class: |
F01L 3/00 20060101
F01L003/00; F01L 3/06 20060101 F01L003/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 31, 2011 |
JP |
2011-121179 |
Claims
1. A port that communicates an inside of a combustion chamber of an
internal combustion engine with an outside of the combustion
chamber, comprising: a throat portion that has at least a portion
of a truncated cone shape; a valve seat portion that is connected
to one end portion of the throat portion to communicate the throat
portion with the inside of the combustion chamber; and a passage
portion that is connected to the other end portion of the throat
portion to communicate the throat portion with the outside of the
combustion chamber.
2. The port according to claim 1, wherein the throat portion is
formed by a portion formed in a truncated cone shape and a portion
formed in a round columnar shape.
3. The port according to claim 1, wherein the throat portion is
formed by only a portion formed in a truncated cone shape.
4. The port according to claim 1, wherein the valve seat portion
has three or more annular surfaces in which an angle defined by any
two adjacent surfaces, from among the three or more annular
surfaces, is the same.
5. The port according to claim 4, wherein a width of each of the
three or more annular surfaces is the same.
6. The port according to claim 1, wherein the valve seat portion
has a plurality of annular surfaces in which a width of each of the
plurality of annular surfaces is the same.
7. The port according to claim 1, wherein the valve seat portion
has four annular surfaces.
8. The port according to claim 1, wherein the throat portion is
connected to the passage portion such that a flow direction of gas
that flows along a peripheral surface of the throat portion is
parallel to a generating line of the truncated cone shape of the
throat portion when gas passes through the throat portion.
9. The port according to claim 8, wherein the throat portion is
connected to the passage portion such that an axis of the throat
portion and an axis of the passage portion are in the same
plane.
10. The port according to claim 1, wherein the throat portion is
connected to the passage portion such that at least a portion of an
extension line of a generating line of the truncated cone shape of
the throat portion is included in a peripheral surface that
includes a boundary line between the passage portion and the throat
portion, and that is a peripheral surface of the passage portion.
Description
INCORPORATION BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2011-121179 filed on May 31, 2011 including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a port of an internal combustion
engine.
[0004] 2. Description of Related Art
[0005] A combustion chamber of an internal combustion engine is
typically communicated with the outside of the combustion chamber
by an intake port so that gas that has not yet been combusted (such
as air, an air-fuel mixture, or the like) can be introduced into
the combustion chamber, as well as communicated with the outside of
the combustion chamber by an exhaust port such that combusted gas
(i.e., exhaust gas) can be discharged outside of the combustion
chamber. The modes in which these gases are introduced and
discharged may have a variety of effects on the characteristics of
the internal combustion engine, as is well known. Among these
modes, a related intake port that is able to smoothly introduce gas
into the combustion chamber and that enables a rotating flow (such
as tumble) caused by the introduced gas to be created inside the
combustion chamber has been proposed.
[0006] For example, one such related intake port (hereinafter, also
referred to as "related port") includes a throat portion, a valve
seat portion that is connected to one end of the throat portion,
and a passage portion that is connected to the other end of the
throat portion. The valve seat portion of the related port has a
plurality of annular surfaces. In this related port, the plurality
of annular surfaces form a virtual curved surface, and the
curvature radius of this curved surface differs depending on the
position in the circumferential direction of the port. With this
related port, the amount of gas introduced into the combustion
chamber is increased, and the degree of rotating flow (i.e.,
tumble) created inside the combustion chamber is increased, by
appropriately setting the curvature radius of this curved surface
according to the position (see Japanese Patent Application
Publication No. 2009-57830 (JP 2009-57830 A), for example). In this
way, from the past it has been desirable to appropriately control
the flow of gas in the combustion chamber.
[0007] The port of an internal combustion engine is typically
formed by separately forming each of the portions (such as the
throat portion, the valve seat portion, and the passage portion of
the related port) that make up the port in order. For example, in a
related port, first a predetermined member (such as a cylinder
head) is cast to form the passage portion. Next, the cast member is
machined to form the throat portion in the end portion of the
passage portion. Then the cast member is further machined to form
the valve seat portion on the end portion of the throat portion. It
is through these processes that the related port in which the valve
seat portion, the throat portion, and the passage portion are
connected is formed.
[0008] However, there may be manufacturing variation among the
portions that make up the port (i.e., differences in dimension and
the like among the same type of part that may occur during
manufacture; hereinafter, simply referred to as "variation"), as is
well known. When the degree of variation is small, the effect of
this variation on the characteristics of the port is negligible
from the viewpoint of appropriately controlling the flow of gas in
the combustion chamber. In contrast, when the degree of variation
is fairly large, the intended characteristics of the port are
unable to be sufficiently obtained, so the flow of gas in the
combustion chamber may not be able to be appropriately
controlled.
SUMMARY OF THE INVENTION
[0009] The invention thus provides a port of an internal combustion
engine in which the intended characteristics of the port are able
to be obtained, even if there is variation among various portions
that make up the port of the internal combustion engine.
[0010] One aspect of the invention relates to a port that
communicates an inside of a combustion chamber of an internal
combustion engine with an outside of the combustion chamber. This
port includes a throat portion that has at least a portion of a
truncated cone shape, a valve seat portion that is connected to one
end portion of the throat portion to communicate the throat portion
with the inside of the combustion chamber, and a passage portion
that is connected to the other end portion of the throat portion to
communicate the throat portion with the outside of the combustion
chamber.
[0011] The port may be provided between an intake passage (e.g., an
intake manifold) of the internal combustion engine and the
combustion chamber, or between an exhaust passage (e.g., an exhaust
manifold) of the internal combustion engine and the combustion
chamber. Further, for example, the port may be provided, as part of
the intake passage, on an end portion of the intake passage where
the intake passage is connected to the combustion chamber, or as
part of the exhaust passage, on an end portion of the exhaust
passage where the exhaust passage is connected to the combustion
chamber. That is, the port may be a part of the intake passage or
the exhaust passage, or may be a portion that is different from the
intake passage and the exhaust passage.
[0012] In other words, the port may form part of a flow path
through which flows gas (e.g., air or an air-fuel mixture of air
and fuel) that is introduced from outside of the combustion chamber
into the combustion chamber, or gas (e.g., exhaust gas) that is
discharged from inside of the combustion chamber to outside of the
combustion chamber. More specifically, the port may be the flow
path itself (i.e., a space or a cavity) through which these gases
pass, or a member that defines this flow path (i.e., the space or
cavity).
[0013] As can be understood from the description above, the outer
peripheral surface of the flow path itself through which gas passes
(i.e., a virtual surface that defines the space of the flow path)
and an inner peripheral surface of the member that defines this
flow path (i.e., an inner peripheral wall surface that defines the
space formed inside of the member for providing the flow path) have
shapes that correspond with each other, and contact each another.
Therefore, in terms of considering the shape of the port, these may
match. Therefore, hereinafter, regarding the port, the outer
peripheral surface of the flow path itself through which gas passes
and the inner peripheral surface of the member that defines this
flow path may each also simply be referred to as a "peripheral
surface of the port". Moreover, regarding the throat portion, the
valve seat portion, and the passage portion as well (the details of
these portions will be described later), similarly, the outer
peripheral surface of the flow path itself through which gas passes
and the inner peripheral surface of the member that defines this
flow path may also simply be referred to as a "peripheral surface
of the throat portion", a "peripheral surface of the valve seat
portion", and a "peripheral surface of the passage portion".
[0014] The throat portion has at least a portion of a truncated
cone shape. In other words, the space that forms the throat portion
may be a space of at least a portion of the space of the truncated
cone shape. The throat portion is a portion that exists between a
valve seat portion and a passage portion that will be described
later, and is where these two portions are connected.
[0015] As described above, the port may be the flow path itself or
a member that defines the flow path. Therefore, in this aspect, the
expression "the throat portion is a truncated cone shape" may refer
to (a) the portion itself (i.e., the space or cavity) that is
referred to as the throat portion of the flow path being a
truncated cone shape, or (b) a member that defines the portion
(i.e., the space or cavity) that is referred to as the throat
portion of the flow path being formed such that this portion is a
truncated cone shape.
[0016] Further, in this aspect, the expression "the throat portion
is at least a portion of the truncated cone shape" may refer to (c)
the throat portion being a complete truncated cone shape (i.e.,
three dimensional surrounded by a round bottom surface and upper
surface, and a band-shaped side surface, or (d) the throat portion
being a shape obtained by removing a portion from a complete
truncated cone (see FIG. 3, for example).
[0017] The expression "the throat portion has at least a portion of
a truncated cone shape" may refer to the throat portion including a
shape understood from (a) to (d) described above (i.e., part or all
of the throat portion being a truncated cone shape). Thus, for
example, the throat portion may be a shape obtained by a
combination of a truncated cone shape and another shape.
[0018] The valve seat portion is connected to one end portion of
the throat portion so as to communicate the throat portion with the
inside of the combustion chamber. In other words, the valve seat
portion is provided on a portion of the port that faces the inside
of the combustion chamber. The valve seat may be a flow path itself
or a member that defines a flow path, just as described above. As
is well known, the amount of gas that passes through the port is
able to be adjusted by having a predetermined member (such as a
valve) come into contact with or move away from the valve seat
portion.
[0019] The shape of the valve seat portion is not particularly
limited. The details of the shape of the valve seat portion will be
described later.
[0020] The passage portion is connected to the other end portion of
the throat portion so as to communicate the throat portion with the
outside of the combustion chamber. The passage portion may be a
flow path itself or a member that defines a flow path, just as
described above.
[0021] The shape of the passage portion is not particularly
limited. For example, a portion having at least a portion of a
round columnar shape, or a portion having at least a portion of a
square columnar shape or the like may be used as the passage
portion. In other words, a passage portion formed by a space of at
least a portion of a space of a round columnar shape, or a passage
portion formed by a space of at least a portion of a space of a
square columnar shape or the like may be used as the passage
portion.
[0022] Hereinafter, the position where the throat portion is
connected to the valve seat portion may also be referred to as a
"connecting position of the throat portion and the valve seat
portion", and the position where the throat portion is connected to
the passage portion may also be referred to as a "connecting
position of the throat portion and the passage portion".
[0023] In the port of this aspect structured as described above,
the flow direction of the gas that passes through the port may
change at the connecting position of the throat portion and the
valve seat portion, and at the connecting position of the throat
portion and the passage portion. For example, when the peripheral
surface of the passage portion is inclined at a specific angle
(hereinafter, also referred to as a "connecting angle") with
respect to the peripheral surface of the throat portion at the
connecting position of the throat portion and the passage portion,
when gas passes by the connecting position, the flow direction of
the gas that flows close to these peripheral surfaces may change
according to the connecting angle (i.e., so as to follow the
peripheral surface of the throat portion and the peripheral surface
of the passage portion).
[0024] Therefore, in order to appropriately control the flow of gas
inside the combustion chamber, it is desirable that the connecting
angle change as little as possible even if there is variation among
the members that make up the port (i.e., the throat portion, the
valve seat portion, and the passage portion).
[0025] However, if the throat portion has a semispherical shape
(i.e., a shape that differs from the truncated cone shape of this
aspect), for example, and the passage portion is connected to a
portion of a spherical surface of this semispherical shape, the
connecting angle of the throat portion and the passage portion may
differ depending on the connecting position of the throat portion
and the passage portion. This is because the connecting angle of
the throat portion and the passage portion corresponds to an angle
that is defined by the peripheral surface of the passage portion
and the tangential plane of the hemisphere at the connecting
position (i.e., an angle formed between the peripheral surface of
the passage portion and the tangential plane of the hemisphere at
the connecting position), and the slope of the tangential plane of
the hemisphere typically differs depending on the connecting
position. Therefore, in this case, if there is variation among the
members that make up the port, this variation may cause the
connecting position of the throat portion and the passage portion
to change, which in turn may cause the connecting angle to change
(see FIG. 4, for example).
[0026] On the other hand, the throat portion of the port of this
aspect has at least a portion of a truncated cane shape. Therefore,
if the passage portion is connected to a portion of the side
surface of the truncated cone shape, the connecting angle of the
throat portion and the passage portion is able to be the same
(constant) regardless of the connecting position of the throat
portion and the passage portion. This is because the connecting
angle of the throat portion and the passage portion corresponds to
an angle that is defined by the peripheral surface of the passage
portion and the side surface of the truncated cone at the
connecting position (i.e., an angle formed between the peripheral
surface of the passage portion and the side surface of the
truncated cone at the connecting position), and the slope of the
side surface of the truncated cone is the same, even if the
connecting position is different, as long as the connecting
position is on the same line of the truncated cone. Accordingly, in
the port of this aspect, even if there is variation among the
members that make up the port, the connecting angle will not change
as long as the connecting position of the throat portion and the
passage portion changes on the same line due to the variation.
Further, with the port of this aspect, if the connecting position
of the throat portion and the passage portion does not change on
the same line, or even if the slope of the peripheral surface of
the passage portion changes, typically the connecting angle is able
to be inhibited from changing compared with the throat portion that
has a semispherical shape described above.
[0027] Furthermore, with the port of this aspect, even if the
passage portion is connected to a portion of an upper surface or a
bottom surface of the truncated cone shape of the throat portion,
the upper surface or the side surface of the truncated cone shape
of the throat portion is a flat surface, so the connecting angle is
able to be inhibited from changing when there is variation among
the members that make up the port, compared with a throat portion
that has a semispherical shape.
[0028] In addition, as can be understood from the description
above, regarding the connecting angle of the throat portion and the
valve seat portion as well, this connecting angle can be inhibited
from changing even if there is variation among the members that
make up the port, just as described above.
[0029] The expression the "passage portion is connected to a
portion of a side surface of the truncated cone shape of the throat
portion" may also be expressed as "at least a portion of a boundary
line between the throat portion and the passage portion is on a
side surface of the truncated cone shape of the throat
portion."
[0030] In this way, the port of this aspect is formed such that
variation among the members (i.e., the throat portion, the valve
seat portion, and the passage portion) that make up the port
affects the characteristics of the port as little as possible
(e.g., such that the connecting angle is maintained at an angle in
a range within which the intended characteristics of the port can
be obtained). Therefore, with the port of this aspect, the intended
characteristics of the port are able to be obtained to the greatest
extent possible, even if there is variation among the members that
make up the port.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Features, advantages, and technical and industrial
significance of exemplary embodiments of the invention will be
described below with reference to the accompanying drawings, in
which like numerals denote like elements, and wherein:
[0032] FIG. 1 is a schematic diagram of an internal combustion
engine to which a port according to a first embodiment of the
invention may be applied;
[0033] FIG. 2 is a view schematically showing a cross section of
the port according to the first embodiment of the invention;
[0034] FIG. 3 is an enlarged perspective view schematically showing
the port according to the first embodiment of the invention;
[0035] FIG. 4 is a schematic diagram of the manner in which gas
passes through a port according to related art;
[0036] FIG. 5 is a schematic diagram of the manner in which gas
passes through the port according to the first embodiment of the
invention;
[0037] FIG. 6 is an enlarged perspective view schematically showing
a port according to a second embodiment of the invention;
[0038] FIG. 7 is a view schematically showing a cross section of
the port according to the second embodiment of the invention;
[0039] FIG. 8 is a view schematically showing a cross section of a
port according to a third embodiment of the invention;
[0040] FIG. 9 is an enlarged perspective view schematically showing
a port according to a fourth embodiment of the invention;
[0041] FIG. 10 is a view schematically showing a cross section of a
port according to related art;
[0042] FIG. 11 is a schematic diagram of the flow, inside of a
combustion chamber, of gas that has passed through the port
according to the related art;
[0043] FIG. 12 is another schematic diagram of the flow, inside of
a combustion chamber, of gas that has passed through the port
according to the related art;
[0044] FIG. 13 is a schematic diagram of the flow, inside of a
combustion chamber, of gas that has passed through the port
according to the fourth embodiment of the invention; and
[0045] FIG. 14 is a graph showing a simple view of the relationship
between tumble ratio and flow coefficient.
DETAILED DESCRIPTION OF EMBODIMENTS
[0046] Hereinafter, embodiments (i.e., first to fourth embodiments)
of a port of an internal combustion engine according to the
invention will be described with reference to the accompanying
drawings.
First Embodiment
Outline of the Port
[0047] FIG. 1 is a view schematically showing the structure of a
system in which ports (i.e., an intake port and an exhaust port)
according to a first embodiment of the invention have been applied
to an internal combustion engine 10. The internal combustion engine
10 is a four-cycle spark-ignition multiple cylinder (four cylinder)
engine. FIG. 1 is a view of only the cross section of one of the
plurality of cylinders. The other cylinders have the same structure
as this cylinder.
[0048] This internal combustion engine 10 includes a cylinder block
portion 20, a cylinder head portion 30 that is fixed to an upper
portion of the cylinder block portion 20, an intake system 40 for
introducing gas that is a mixture of air and fuel (i.e., an
air-fuel mixture) into the cylinder block portion 20, an exhaust
system 50 for discharging gas (i.e., exhaust gas) from the cylinder
block portion 20 to outside of the internal combustion engine 10,
an accelerator pedal 61, various sensors 71 to 78, and an
electronic control unit (ECU) 80.
[0049] The cylinder block portion 20 includes a cylinder 21, a
piston 22, a connecting rod 23, and a crankshaft 24. The piston 22
moves in a reciprocating manner inside the cylinder 21. This
reciprocating movement of the piston 22 is transmitted to the
crankshaft 24 via the connecting rod 23, causing the crankshaft 24
to rotate. A combustion chamber 25 is defined by an inner
peripheral surface of the cylinder 21, an upper surface of the
piston 22, and a lower surface of the cylinder head portion 30.
[0050] The cylinder head portion 30 includes an intake port 31 that
is communicated with the combustion chamber 25, an intake valve 32
that opens and closes the intake port 31, an intake camshaft 33
that drives the intake valve 32, an injector 34 that injects fuel
into the intake port 31, an exhaust port 35 that is communicated
with the combustion chamber 25, an exhaust valve 36 that opens and
closes the exhaust port 35, an exhaust camshaft 37 that drives the
exhaust valve 36, a spark plug 38, and an igniter 39 that includes
an ignition coil that generates high voltage that is applied to the
spark plug 38.
[0051] FIG. 2 is a view schematically showing a cross section of
the combustion chamber 25, the intake port 31, and the exhaust port
35 when a region including the combustion chamber 25, the intake
port 31, and the exhaust port 35 has been cut along a plane
parallel to the axis of the combustion chamber 25. To facilitate
understanding, members (such as the spark plug 38) that are not
absolutely necessary to describe the structure of the port
according to this embodiment are not shown in FIG. 2.
[0052] Hereinafter, of the ports according to the first embodiment,
the intake port 31 will be described in more detail. As shown in
FIG. 2, the intake port 31 includes a valve seat portion 31a, a
throat portion 31b, and a passage portion 31c.
[0053] In this embodiment, the intake port 31 represents a flow
path itself, through which an air-fuel mixture flows, that is
between the combustion chamber 25 and an intake manifold 41 that
will be described later, or a member that defines this flow
path.
[0054] The valve seat portion 31a is connected to one end portion
of the throat portion 31b (i.e., the end portion closer to the
combustion chamber 25 than the other end portion that will be
described later; hereinafter this one end portion will be referred
to as a "combustion chamber side end portion") so as to communicate
the throat portion 31b with the inside of the combustion chamber
25. Meanwhile, the passage portion 31c is connected to the other
end portion of the throat portion 31b (i.e., the end portion that
is closer to the intake system 40 than the one end portion
described above; hereinafter this other end portion will be
referred to as an "intake side end portion") so as to communicate
the throat portion 31b with the outside of the combustion chamber
25. The throat portion 31b is located between the valve seat
portion 31a and the passage portion 31c, and is connected to both
the valve seat portion 31a and the passage portion 31c.
[0055] FIG. 3 is an enlarged perspective view schematically showing
the intake port 31. As shown in FIG. 3, the throat portion 31b has
a portion of a truncated cone shape (hereinafter, simply referred
to as a "truncated cone portion") 31b1, and a portion 31b2 of
another shape (a round columnar shape in this embodiment). The
truncated conical portion 31b1 has a shape that can be obtained by
removing a portion (i.e., a region 31b3 indicated by the broken
line) from a complete truncated cone, as shown by the hatched
portion. In this way, the throat portion 31b has at least a portion
of a truncated cone shape.
[0056] In this embodiment, the throat portion 31b having at least a
portion of a truncated cone shape represents to a portion referred
to as the throat portion of the flow path through which the
air-fuel mixture flows having at least a portion of a truncated
cone shape, or a member that defines the portion being formed such
that the portion has at least a portion of a truncated cone
shape.
[0057] The passage portion 31c is connected to a portion of a side
surface of the truncated cone shape (i.e., the truncated cone
portion) 31b1 of the throat portion 31b. In other words, at least a
portion (all in this embodiment) of a boundary line between the
throat portion 31b and the passage portion 31c is on a side surface
of the truncated cone shape 31b1 of the throat portion 31b. The
passage portion 31c has a round columnar shape.
[0058] The valve seat portion 31a is connected to the portion 31h2
of another shape (i.e., a round columnar shape) of the throat
portion 31b. The valve seat portion 31a may also be connected to a
bottom surface of the truncated cone portion 31b1 (not via the
portion 31b2 of another shape). In other words, the throat portion
31b may also be connected to the valve seat portion 31a such that
at least a portion of a boundary line between the throat portion
31b and the valve seat portion 31a is on a bottom surface of the
truncated cone shape of the throat portion 31b.
[0059] When the air-fuel mixture passes through the intake port 31
and is introduced into the combustion chamber 25, the air-fuel
mixture passes through the passage portion 31c, the throat portion
31b, and the valve seat portion 31a in this order (see arrow IN in
FIG. 2). In this way, the intake port 31 forms a portion of the
flow path through which the air-fuel mixture introduced from
outside of the combustion chamber 25 into the combustion chamber 25
passes.
[0060] Hereinafter, regarding the intake port 31, the outer
peripheral surface of the flow path itself through which the
air-fuel mixture passes and the inner peripheral surface of the
member that defines this flow path may also be referred to as a
"peripheral surface of the intake port 31". Similarly, regarding
the valve seat portion 31a, the throat portion 31b, and the passage
portion 31c, hereinafter, the outer peripheral surface of the flow
path itself through which the air-fuel mixture passes and the inner
peripheral surface of the members that define this flow path may
also be referred to as a "peripheral surface of the valve seat
portion 31a", a "peripheral surface of the throat portion 31b", and
a "peripheral surface of the passage portion 31c".
[0061] Referring back to FIG. 2 again, the exhaust port 35 has the
same structure as the intake port 31 (i.e., has the throat portion,
a valve seat portion, and a passage portion). Here, a detailed
description of the structure of the exhaust port 35 will be
omitted. When exhaust gas passes through the exhaust port 35 and is
discharged from the combustion chamber 25, the exhaust gas passes
through the valve seat portion, the throat portion, and the passage
portion in this order (see arrow EX in FIG. 2). In this embodiment,
the exhaust port 35 represents a flow path itself through which
exhaust gas passes that is between the combustion chamber 25 and an
exhaust manifold 51 that will be described later, or a member that
defines this flow path.
[0062] The passage through which the air-fuel mixture passes is
closed off by the intake valve 32 contacting the valve seat portion
31a of the intake port 31 structured as described above, and the
passage through which the air-fuel mixture passes is Opened by the
intake valve 32 coming away from the valve seat portion 31a. That
is, the intake port 31 opens and closes according to the intake
valve 32, and similarly, the exhaust port 35 opens and closes
according to the exhaust valve 36.
[0063] Referring back to FIG. 1 again, the intake system 40
includes an intake manifold 41 that is communicated to each
cylinder via the intake port 31 described above, an intake pipe 42
that is connected to a converging portion upstream of the intake
manifold 41, an air cleaner 43 provided on an end portion of the
intake pipe 42, a throttle valve (i.e., an intake throttle valve)
44 capable of changing the opening area (i.e., the opening
sectional area) of the intake pipe 42, and a throttle valve
actuator 44a that rotatably drives the throttle valve 44 according
to a command signal. The intake port 31, the intake manifold 41,
and the intake pipe 42 together form an intake passage.
[0064] The exhaust system 50 includes an exhaust manifold 51 that
is communicated with each of the cylinders via the exhaust port 35
described above, an exhaust duct 52 that is connected to a
converging portion downstream of the exhaust manifold 51, and an
exhaust gas control catalyst 53 provided in the exhaust duct 52.
The exhaust port 35, the exhaust manifold 51, and the exhaust duct
52 together form an exhaust passage.
[0065] Referring to FIG. 1 again, the accelerator pedal 61 for
inputting an acceleration request and the required torque and the
like to the internal combustion engine 10 is provided outside of
the internal combustion engine 10. The accelerator pedal 61 is
operated by an operator of a vehicle provided with the internal
combustion engine 10.
[0066] The internal combustion engine 10 is provided with various
sensors, such as an intake air amount sensor 71, a throttle valve
opening amount sensor 72, a crank position sensor 73, a coolant
temperature sensor 74, air-fuel ratio sensors 75 and 76, and an
accelerator operation amount sensor 77.
[0067] Of these sensors, the crank position sensor 73 is provided
near the crankshaft 24. The crank position sensor 73 is configured
to output a signal having a narrow pulse width every time the
crankshaft 24 rotates 10.degree., and output a signal having a wide
pulse width every time the crankshaft 24 rotates 360.degree.. The
rotation speed per unit time of the crankshaft 24 (hereinafter,
also simply referred to as "engine speed NE") can be obtained based
on these signals.
[0068] Furthermore, the internal combustion engine 10 includes the
ECU 80. The ECU 80 includes a CPU 81, ROM 82 in which programs to
be executed by the CPU 81, as well as constants and tables (maps),
have been stored in advance, RAM 83 in which data is temporarily
stored as necessary by the CPU 81, back-up RAM 84 that stores data
when a power supply is on and retains the stored data while the
power supply is off, and an interface 85 that includes an AD
converter. The CPU 81, the ROM 82, the RAM 83, the back-up RAM 84,
and the interface 85 are all connected together by a bus.
[0069] The interface 85 is connected to the various sensors and is
configured to transmit the signals output from these sensors to the
CPU 81. Furthermore, the interface 85 is connected to the injector
34, the igniter 39, and the throttle valve actuator 44a and the
like, and is configured to send command signals to these according
to a command from the CPU 81.
Relationship Between Variation and Flow of Air-Fuel Mixture
[0070] As described above, there may be variation among the members
that make up the intake port 31. Next, the relationship between
variation among the members that make up the intake port 31 and the
flow of air-fuel mixture that passes through the intake port 31
will be described.
[0071] First, before describing this relationship with respect to
the intake port 31 according to the first embodiment, this
relationship with respect to an intake port according to related
art will be described. FIG. 4 is a schematic diagram of the manner
in which gas passes through an intake port 91 according to related
art. As shown in FIG. 4, the intake port 91 according to the
related art differs from the intake port 31 according to the first
embodiment of the invention in that the throat portion has a
portion in the shape of an ellipsoid (in other words, in a
semispherical shape).
[0072] Reference character A in FIG. 4 denotes a peripheral surface
of a passage portion when there is no variation among the members
that make up the intake port 91. In this case, the size of the
angle defined by the peripheral surface A of the passage portion
and a tangential plane (the alternate long and short dash line in
the drawing) of the throat portion, in a position where the
peripheral surface A of the passage portion is connected to the
throat portion is angle .alpha..
[0073] When the air-fuel mixture that flows close to the peripheral
surface A of the passage portion passes through the intake port 91,
it is assumed that the air-fuel mixture flows along the peripheral
surface A of the passage portion and the peripheral surface of the
throat portion, as shown by the solid arrow in the drawing.
[0074] On the other hand, reference character B in FIG. 4 denotes a
peripheral surface B of the passage portion when there is variation
among the members that make up the intake port 91. More
specifically, in this case, there is variation such that the
position where the peripheral surface of the passage portion is
connected to the throat portion approaches the center (i.e., the
axis) of the passage portion (i.e., shifts upward in the drawing)
by .delta.. Hereinafter, this variation may also be referred to as
"variation .delta.". The slope of the tangential plane of the
ellipsoid typically differs depending on the position where the
throat portion is connected to the passage portion, so in this
case, the size of the angle defined by the peripheral surface B of
the passage portion and the tangential plane (i.e., the alternate
long and short dash line in the drawing) of the throat portion is
angle .beta. that is different from angle .alpha.. In this
embodiment, angle .beta. is smaller than angle .alpha..
[0075] When the air-fuel mixture that flows close to the peripheral
surface B of the passage portion passes through the intake port 91,
the air-fuel mixture may not flow along the peripheral surface B of
the passage portion and the peripheral surface of the throat
portion because angle .beta. is smaller than angle .alpha.. For
example, as shown by the broken arrow in the drawing, the air-fuel
mixture may flow in a different direction than the solid arrow
described above due to the air-fuel mixture separating from these
peripheral surfaces at the position where the peripheral surface B
of the passage portion is connected to the throat portion.
[0076] That is, the flow direction of the air-fuel mixture that
passes through the intake port 91 when there is no variation among
the members that make up the intake port 91 may be different from
the flow direction of that air-fuel mixture when there is variation
among these members. If the flow direction of the air-fuel mixture
that passes through the intake port 91 changes, the intended
characteristics of the intake port (such as the tumble ratio that
will be described later with reference to FIG. 13, for example) may
be unable to be obtained.
[0077] In contrast, FIG. 5 is a schematic diagram of the manner in
which gas passes through the intake port 31 according to the first
embodiment of the invention. As described above, reference
character A in FIG. 5 denotes a peripheral surface of the passage
portion when there is no variation among the members that make up
the intake port 31, and reference character B in FIG. 5 denotes a
peripheral surface of the passage portion when there is the same
variation .delta. as described above among the members.
[0078] The slope of the side surface of the truncated cone
typically will not change as long as the position where the passage
portion is connected to the throat portion changes on the same
line. Therefore, the size of the angle defined by the passage
portion, the peripheral surface A, and the side surface of the
throat portion, and the size of the angle defined by the passage
portion, the peripheral surface B, and the side surface of the
throat portion are the same angle .gamma.. Therefore, the air-fuel
mixture that flows close to the peripheral surface A of the passage
portion (i.e., the solid arrow in the drawing) and the air-fuel
mixture that flows close to the peripheral surface B of the passage
portion (i.e., the broken arrow in the drawing) flow in essentially
the same direction.
[0079] That is, the flow direction of the air-fuel mixture that
passes through the intake port 31 when there is no variation among
the members that make up the intake port 31 is essentially the same
as the flow direction of that air-fuel mixture when there is
variation among those members.
[0080] In this way, even if there is variation among the members
that make up the intake port 31, the intake port 31 according to
the first embodiment of the invention is able to inhibit a change
in the flow direction of the air-fuel mixture that passes through
the intake port due to this variation, compared with the intake
port 91 according to the related art. As a result, with the intake
port 31, the intended characteristics of the port are able to be
obtained to the greatest extent possible.
Second Embodiment
[0081] Next, a port according to a second embodiment of the
invention will be described.
Outline of the Port
[0082] The port according to the second embodiment of the invention
differs from the port according to the first embodiment described
above only in that the valve seat portion has a specific mode.
Therefore, the port according to the second embodiment will be
described in detail focusing on this difference. In FIGS. 6 and 7
described below, members that are the same as those that make up
the port according to the first embodiment will be denoted by the
same reference characters as those denoting the members in the
first embodiment.
[0083] FIG. 6 is an enlarged perspective view schematically showing
the port 31 that is the port according to the second embodiment.
Just like the intake port according to the first embodiment, the
valve seat portion 31a is connected to a combustion chamber side
end portion of the throat portion 31b so as to communicate the
throat portion 31b with the inside of the combustion chamber 25.
Moreover, the valve seat portion 31a has a plurality (four in this
embodiment) of annular surfaces, as shown by the hatched portion.
One of these four annular surfaces is connected to another of the
surfaces that is adjacent to this one surface. Each of the four
annular surfaces is a ring formed by a closed band having a flat
surface.
[0084] FIG. 7 is a view schematically showing a cross section of
the combustion chamber 25, the intake port 31, and the exhaust port
35 when a region including the combustion chamber 25, the intake
port 31, and the exhaust port 35 has been cut along a plane
parallel to the axis of the combustion chamber 25. Moreover, in
FIG. 7, an enlarged view of the area (i.e., portion C in the
drawing) near the boundary between the combustion chamber 25 and
the valve seat portion 31a of the intake port 31 is also shown.
[0085] As shown in the enlarged view of portion C, the size of an
angle defined by a first surface 31a1 and a second surface 31a2
adjacent to the first surface 31a1, from among the four annular
surfaces, is angle .theta.. Further, the size of an angle defined
by the second surface 31a2 and a third surface 31a3 adjacent to the
second surface 31a2 is also Angle .theta.. In addition, the size of
an angle defined by the third surface 31a3 and a fourth surface
31a4 adjacent to the third surface 31a3 is also angle .theta.. That
is, each angle defined by two adjacent surfaces among the four
annular surfaces is the same (i.e., angle .theta.).
[0086] The intake port 31 according to the second embodiment having
the structure described above may be applied to an internal
combustion engine having a structure similar to that of the
internal combustion engine 10 described above (see FIG. 1).
Flow of Air-Fuel Mixture that Passes Through the Valve Seat
Portion
[0087] When the air-fuel mixture passes through the valve seat
portion 31a, the flow direction of the air-fuel mixture that flows
close to the peripheral surface of the valve seat portion 31a will
change by the same angle .theta. each time the air-fuel mixture
passes by a connecting position of the four annular surfaces.
Therefore, it is unlikely that the air-fuel mixture will separate
from the valve seat portion 31a, compared with a valve portion in
which these angles are not the same.
[0088] Therefore, the intake port 31 is more appropriately able to
control the flow of gas in the combustion chamber 25.
[0089] The angle defined by two adjacent surfaces from among the
four annular surfaces is not particularly limited as long as it is
an angle at which separating can be inhibited, taking into account
the characteristics of the air-fuel mixture and the like. For
example, the angle may be 15.degree..
Third Embodiment
[0090] Next, a port according to a third embodiment of the
invention will be described.
Outline of the Port
[0091] The port according to the third embodiment of the invention
differs from the port according to the first embodiment described
above only in that the valve seat portion has a specific mode.
Therefore, the port according to the third embodiment will be
described in detail focusing on this difference. In FIG. 8
described below, members that are the same as those that make up
the port according to the first embodiment will be denoted by the
same reference characters as those denoting the members in the
first embodiment.
[0092] FIG. 8 is a view schematically showing a cross section of
the combustion chamber 25, the intake port 31, and the exhaust port
35 when a region including the combustion chamber 25, the intake
port 31, and the exhaust port 35 has been cut along a plane
parallel to the axis of the combustion chamber 25. Moreover, in
FIG. 8, an enlarged view of the area (i.e., portion D in the
drawing) near the boundary between the combustion chamber 25 and
the valve seat portion 31a of the intake port 31 is also shown.
[0093] Just like the intake port according to the second embodiment
described above, the intake port 31 has a plurality (four in this
embodiment) of annular surfaces that are connected together. As
shown in the enlarged view of portion D, the size of the width of
the first surface 31a1 among the four annular surfaces is width w.
Furthermore, the size of the width of the second surface 31a2 is
also width w. In addition, the size of the width of the third
surface 31a3 is also width w, and the size of the width of the
fourth surface 31a4 is also width w. That is, the width of the each
of the four annular surfaces is the same (i.e., width w).
[0094] The intake port 31 according to the third embodiment having
the structure described above may be applied to an internal
combustion engine having a structure similar to that of the
internal combustion engine 10 described above (see FIG. 1).
Flow of Air-Fuel Mixture that Passes Through the Valve Seat
Portion
[0095] When the air-fuel mixture passes through the valve seat
portion 31a, the flow direction of the air-fuel mixture that flows
close to the peripheral surface of the valve seat portion 31a will
change with each advance of the same distance (i.e., width w).
Therefore, it is unlikely that the air-fuel mixture will separate
from the valve seat portion 31a, compared with a valve portion in
which these widths are not the same.
[0096] Therefore, the intake port 31 is more appropriately able to
control the flow of gas in the combustion chamber 25.
Fourth Embodiment
[0097] Next, a port according to a fourth embodiment of the
invention will be described.
Outline of the Port
[0098] The port according to the fourth embodiment of the invention
differs from the port according to the first embodiment described
above only in that the throat portion and the passage portion are
connected in a specific way. Therefore, the port according to the
fourth embodiment will be described in detail focusing on this
difference. In FIGS. 9 and 13 described below, members that are the
same as those that make up the port according to the first
embodiment will be denoted by the same reference characters as
those denoting the members in the first embodiment.
[0099] FIG. 9 is an enlarged perspective view schematically showing
a port 31 that is the port according to the fourth embodiment. Just
like the intake port according to the first embodiment, the passage
portion 31c is connected to the intake side end portion of the
throat portion 31b so as to communicate the throat portion 31b with
the outside of the combustion chamber 25.
[0100] More specifically, the throat portion 31b and the passage
portion 31c are connected together such that an axis E of the
throat portion 31b and an axis F of the passage portion 31c are in
the same plane.
[0101] Further, the throat portion 31b and the passage portion 31c
are connected together such that at least a portion of an extension
line 31bext of a generating line 31bgen of the truncated cone shape
31b1 of the throat portion 31b (hereinafter this extension line
31bext may also be referred to as a "generating line extension line
31bext") is included in a peripheral surface 31cper that includes a
boundary line 31bcbo between the passage portion 31c and the throat
portion 31b, and that is a peripheral surface of the passage
portion 31c (hereinafter this peripheral surface may also be
referred to as a "peripheral surface close to the connecting
position").
[0102] In other words, the throat portion 31b and the passage
portion 31c are connected together such that an angle defined by
the side surface of the truncated cone shape 31b1 of the throat
portion 31b and the peripheral surface 31cper close to the
connecting position is zero (or 180.degree.) on the generating line
extension line 31bext.
[0103] The intake port 31 according to the fourth embodiment having
the structure described above may be applied to an internal
combustion engine having a structure similar to that of the
internal combustion engine 10 described above (see FIG. 1).
Flow of Gas Inside the Combustion Chamber
[0104] Next, the flow in the combustion chamber 25 of the air-fuel
mixture that has passed through the intake port 31 will be
described.
[0105] First, before the flow in the intake port 31 according to
the fourth embodiment is described, the flow inside the combustion
chamber 25 of the air-fuel mixture that has passed through an input
port of related art will be described. FIG. 10 is a view
schematically showing a cross section of the combustion chamber 25,
an intake port 101, and an exhaust port 102 when a region including
the combustion chamber 25, the intake port 101, and the exhaust
port 102 has been cut along a plane parallel to the axis of the
combustion chamber 25, in an internal combustion engine 10 to which
the intake port 101 and the exhaust port 102 according to related
art have been applied. Similar to FIG. 2, members that are not
absolutely necessary to describe the structure of the ports
according to this embodiment are not shown in FIG. 10.
[0106] The intake port 101 of the related art differs from the
intake port 31 according to the fourth embodiment of the invention
only in that a throat portion 101b has at least a portion of an
ellipsoid shape (in other words, has a semispherical shape). That
is, a valve seat portion 101a and a passage portion 101c of the
related art have the same shapes as the valve seat portion 31a and
the passage portion 31c, respectively, of the intake port 31
according to the fourth embodiment of the invention, and are
connected to the throat portion 101b, just as with the intake port
31.
[0107] FIG. 11 is a schematic diagram of an example of the flow
inside the combustion chamber 25 of air-fuel mixture that has
flowed through the intake port 101 of the related art when the
intake valve 32 is open and the exhaust valve 36 is closed (i.e.,
during an intake stroke).
[0108] As shown in FIG. 11, of the air-fuel mixture introduced into
the combustion chamber 25, an air-fuel mixture INdir that flows
toward a side surface 25a of the combustion chamber 25 that is
farthest away from the intake port 101 (hereinafter, this side
surface 25a will be referred to as an "exhaust side peripheral
surface 25a") passes through the intake port 101 by flowing along a
peripheral surface 101bus near the exhaust side peripheral surface
25a of the peripheral surface of the throat portion (hereinafter,
this peripheral surface 101bus may also be referred to as an "upper
peripheral surface 101bus"). The air-fuel mixture INdir is denoted
by the solid line in the drawing.
[0109] The throat portion in the related art has a semispherical
shape, so when the air-fuel mixture INdir passes through the throat
portion, the flow direction of the air-fuel mixture INdir changes
so that it is along the upper peripheral surface 101bus of the
throat portion (i.e., changes to a direction toward the intake
valve 32 in the drawing; in other words, changes to a direction
away from a peripheral surface 101aus of the valve seat portion).
As a result, as shown in FIG. 11, the air-fuel mixture INdir may
separate from the peripheral surface of the intake port 101 near
the position where the upper peripheral surface 101bus of the
throat portion is connected to the peripheral surface 101aus of the
valve seat portion.
[0110] On the other hand, of the air-fuel mixture introduced into
the combustion chamber 25, an air-fuel mixture INinv that flows
toward a peripheral surface 25b of the combustion chamber 25 that
is closest to the intake port 101 (hereinafter, this peripheral
surface 25b will be referred to as an "intake side peripheral
surface 25b") passes through the intake port 101 by flowing along a
peripheral surface 101cls of the passage portion, and a peripheral
surface 101bls that is close to the intake side peripheral surface
25b, from among the peripheral surfaces of the throat portion
(hereinafter, this peripheral surface 101bls may also be referred
to as a "lower peripheral surface 101bls"). The air-fuel mixture
INinv is denoted by the broken line in the drawing.
[0111] This air-fuel mixture INdir is able to be introduced into
the combustion chamber 25 without separating from the peripheral
surface of the intake port 101, as shown in FIG. 11, as long as the
connecting angle between the lower peripheral surface 101bls of the
throat portion and the peripheral surface 101cls of the passage
portion, and the connecting angle between the lower peripheral
surface 101bls of the throat portion and a peripheral surface
101als of the valve seat portion, are appropriate.
[0112] In this way, with the intake port 101 of the related art,
the air-fuel mixture INdir that flows close to the upper peripheral
surface 101bus of the throat portion may separate from the
peripheral surface of the intake port 101. In this case, the
air-fuel mixture INdir is not suitably introduced into the
combustion chamber 25, so the flow of the air-fuel mixture inside
of the combustion chamber 25 is unable to be appropriately
controlled. For example, the tumble ratio and the flowrate of the
air-fuel mixture introduced into the combustion chamber 25 will not
be sufficiently increased (see also FIG. 13 that will be described
later).
[0113] One conceivable way to prevent the air-fuel mixture INdir
from separating from the intake port 101 is to incline the intake
port 101 to a degree at which the air-fuel mixture INdir will not
separate from the side surface of the intake port 101 near the
position where the upper peripheral surface 101bus of the throat
portion is connected to the peripheral surface 101aus of the valve
seat portion. For example, as shown in FIG. 12, the intake port 101
may be inclined such that an axis of the intake port 101 matches an
axis H that is inclined by an angle .epsilon. with respect to an
axis G of the intake port 101 in FIG. 11.
[0114] If the intake port 101 is inclined as described above, the
air-fuel mixture INdir that flows toward the exhaust side
peripheral surface 25a will flow in a direction closer to the
peripheral surface 101aus of the valve seat portion than that shown
in FIG. 11. Therefore, the air-fuel mixture INdir is able to be
introduced into the combustion chamber 25 without separating from
the peripheral surface of the intake port 101.
[0115] If the intake port 101 is inclined as described above, the
connecting angle between the lower peripheral surface 101bls of the
throat portion and the peripheral surface 101cls of the passage
portion, or the connecting angle between the lower peripheral
surface 101bls of the throat portion and the peripheral surface
101als of the valve seat portion, will change. Therefore, the
air-fuel mixture INinv may separate from the peripheral surface of
the intake port 101 close to the position where the lower
peripheral surface 101bls of the throat portion is connected to the
peripheral surface 101als of the valve seat portion, for
example.
[0116] In this way, if the intake port 101 of the related art is
inclined, even though the air-fuel mixture INdir that flows close
to the upper peripheral surface 101bus of the throat portion is
able to be prevented from separating from the intake port 101, the
air-fuel mixture INinv that flows close to the lower peripheral
surface 101bls of the throat portion may separate from the
peripheral surface of the intake port 101. In this case, the flow
of the air-fuel mixture inside of the combustion chamber 25 is
unable to be appropriately controlled, just as described above.
[0117] In contrast, FIG. 13 is a schematic diagram of an example of
flow inside of the combustion chamber 25 of the air-fuel mixture
that has passed through the intake port 31 according to the fourth
embodiment of the invention. Just as described above, members that
are not absolutely necessary to describe the structure of the port
according to this embodiment are not shown in FIG. 13.
[0118] As shown in FIG. 13, in the intake port 31 of this
embodiment, neither the air-fuel mixture INdir nor the air-Rid
mixture INinv separate from the intake port 31, and the air-fuel
mixture INdir creates a rotating flow (i.e., tumbling flow) inside
of the combustion chamber 25.
[0119] More specifically, first the air-fuel mixture INdir that
flows toward the exhaust side peripheral surface 25a passes through
the intake port 31 by flowing along an upper peripheral surface
31bus of the intake port 31. In the intake port 31, the throat
portion 31b and the passage portion 31c are connected together such
that the axis E of the throat portion 31b and the axis F of the
passage portion 31c are in the same plane, as described above.
Therefore, when the air-fuel mixture passes through the throat
portion 31b, the flow direction of the air-fuel mixture that flows
along the peripheral surface of the throat portion 31b is parallel
to the generating line 31bgen of the truncated cone shape 31b1 of
the throat portion 31b.
[0120] Therefore, the air-fuel mixture INdir differs from that of
the related art (i.e., the flow direction of the air-fuel mixture
when it passes through the throat portion 101b changes; see FIG.
11), and is able to pass through the intake port 31 without
separating from the intake port 31 near the position where the
upper peripheral surface 31bus of the throat portion is connected
to a peripheral surface 31aus of the valve seat portion.
[0121] Moreover, with the intake port 31, the throat portion 31b is
connected to the passage portion 31c such that at least a portion
of the generating line extension line 31bext of the truncated cane
shape 31b1 of the throat portion 31b is included in the peripheral
surface 31cper that is close to the connecting position of the
passage portion 31c (see FIG. 9). Therefore, when the air-fuel
mixture INdir passes through the passage portion and the throat
portion, the flow direction of the air-fuel mixture INdir does not
change.
[0122] Accordingly, when the air-fuel mixture INdir passes through
the passage portion and the throat portion, the flow direction of
the air-fuel mixture INdir does not change, so compared with the
related art described above, the energy loss of the air-fuel
mixture INdir when the air-fuel mixture INdir passes through the
intake port 31 is able to be reduced.
[0123] In this embodiment, the direction of the generating line
extension line 31bext of the throat portion 31b (see FIG. 9; this
direction corresponds to the direction of axis F of the intake port
31 in FIG. 13) is adjusted so that the angular velocity .omega. of
the rotating flow (i.e., the tumble) created inside of the
combustion chamber 25 by the air-fuel mixture INdir is as large as
possible. For example, the direction of the generating line
extension line 31bext of the throat portion 31b is adjusted so that
the flowrate of the air-fuel mixture INdir when the air-fuel
mixture INdir reaches the exhaust side peripheral surface 25a of
the combustion chamber 25 is as large as possible (simply put, so
that it heads straight toward the exhaust side peripheral surface
25a).
[0124] More specifically, the air-fuel mixture INdir that has been
introduced into the combustion chamber 25 flows along the exhaust
valve 36, the exhaust side peripheral surface 25a, the piston 22,
and the intake side peripheral surface 25b, in this order. As a
result, the air-fuel mixture INdir creates a rotating flow
(so-called tumble) that rotates around an axis perpendicular to the
axis of the combustion chamber 25, in the combustion chamber
25.
[0125] Here, typically a ratio (.omega./NE) of the angular velocity
.omega. of the rotating flow (i.e., tumble) inside of the
combustion chamber 25 with respect to the engine speed NE of the
internal combustion engine 10 will be referred to as the tumble
ratio. As can be understood from this description, the value of the
tumble ratio increases as the angular velocity .omega. of the
tumble with respect to the unit value of the engine speed NE
increases (i.e., as stronger tumble is created inside the
combustion chamber 25). One method that may be used to calculate
the tumble ratio is a method that calculates the tumble ratio based
on, for example, the results of a measurement taken in advance
using a test engine having a structure similar to that of the
internal combustion engine 10, or the results of a simulation that
estimates the flow of air-fuel mixture inside the combustion
chamber 25.
[0126] As described above, in this embodiment, the angular velocity
.omega. of the rotating flow (i.e., tumble) can be increased by
adjusting the direction of the generating line extension line
31bext of the throat portion 31b (in other words, the flow
direction of the air-fuel mixture introduced into the combustion
chamber 25). Therefore, the internal combustion engine 10 that uses
the intake port 31 according to this embodiment is able to increase
the tumble ratio more than the internal combustion engine 10 that
uses the intake port 101 according to the related art.
[0127] When the tumble ratio is increased, flame propagation when
the air-fuel mixture is combusted progresses more smoothly, so the
air-fuel mixture is able to be combusted more efficiently. As a
result, fuel efficiency is able to be improved, for example.
[0128] Furthermore, the air-fuel mixture INinv that flows toward
the intake side peripheral surface 25b passes through the intake
port 31 by flowing along a peripheral surface 31cls of the passage
portion, a lower peripheral portion 31bls of the throat portion,
and a peripheral portion 31als of the valve seat portion. With the
intake port 31 of this embodiment, the air-fuel mixture INdir that
flows close to the upper peripheral surface 31bus of the throat
portion can be prevented from separating from the intake port 31
without inclining the intake port as in the related art (FIG. 12),
as described above. Therefore, the connecting angle between the
lower peripheral surface 31bls of the throat portion and the
peripheral surface 31cls of the passage portion, and the connecting
angle between the lower peripheral surface 31bls of the throat
portion and the peripheral surface 31als of the valve seat portion
can be set to appropriate angles at which the air-fuel mixture
INdir will not separate. Accordingly, the air-fuel mixture INdir
can be introduced into the combustion chamber 25 without separating
from the peripheral surface of the intake port 31.
[0129] As described above, in this embodiment, the air-fuel mixture
(both the air-fuel mixture INinv and the air-fuel mixture INdir)
that passes through the intake port 31 can be prevented from
separating from the intake port 31. Therefore, the internal
combustion engine 10 in which the intake port 31 of this embodiment
is employed is able to increase the flowrate of the air-fuel
mixture that is introduced into the combustion chamber 25 more than
the internal combustion engine 10 in which the intake port 101 of
the related art is employed.
[0130] Increasing the flowrate of the air-fuel mixture introduced
into the combustion chamber 25 enables the energy generated when
the air-fuel mixture is combusted to be increased, so the output of
the internal combustion engine 10 is able to be increased.
[0131] In this embodiment, the tumble ratio is able to be increased
by adjusting the flow direction of the air-fuel mixture that is
introduced into the combustion chamber 25, so the flowrate of the
air-fuel mixture does not need to be increased (e.g., the opening
diameter of the port does not need to be made smaller) in order to
increase the tumble ratio. Therefore, an increase in the
temperature of the air-fuel mixture due to an increase in the
flowrate of the air-fuel mixture, as well as an increase in
knocking caused by this increase in temperature of the air-fuel
mixture, can be inhibited. Also, a decrease in the flowrate of the
air-fuel mixture due to the opening diameter of the port being
smaller, as well as a decrease in the output of the internal
combustion engine 10 due to this decrease in the flowrate of the
air-fuel mixture, can also be inhibited.
[0132] As described above, the intake port 31 according to the
fourth embodiment is able to appropriately control the flow of the
air-fuel mixture inside of the combustion chamber 25. As a result,
the intended characteristics of the port can be more reliably
obtained.
[0133] As can be understood from the description above, combining
the intake port 31 according to the first embodiment (i.e.,
suppressing the effects from variation), the intake port 31
according to the second or third embodiment described above (i.e.,
the shape of the valve seat portion), and the intake port 31
according to the fourth embodiment (i.e., the way in which the
throat portion and the passage portion are connected) enables the
flowrate of the air-fuel mixture that is introduced into the
combustion chamber 25 and the tumble ratio to be further improved,
while suppressing the effects from variation among the members that
make up the intake port 31. For example, as shown in the graph
showing a simple view of the relationship between the flowrate and
the tumble ratio in FIG. 14, the port of the invention is able to
increase both the tumble ratio and the flowrate more than the port
of the related art (see FIG. 10), while reducing the effects that
variation has on the tumble ratio and the flowrate more than the
port of the related art (see FIG. 10).
Summary of the Embodiments
[0134] As described above, the ports according to the embodiments
(i.e., the first through the fourth embodiments) of the invention
are provided with the throat portion 31b that has at least a
portion of a truncated cone shape (the truncated cone portion 31b1
in FIG. 3), the valve seat portion 31a that is connected to one end
portion (i.e., the combustion chamber side end portion) of the
throat portion 31b so as to communicate the throat portion 31b with
the inside of the combustion chamber 25, and the passage portion
31c that is connected to the other end portion (i.e., the intake
side end portion) of the throat portion 31b so as to communicate
the throat portion 31b with the outside of the combustion chamber
25 (see FIGS. 2 and 3, for example).
[0135] In the ports according to the embodiments, the valve seat
portion 31a has three or more annular surfaces (such as four
annular surfaces; see FIG. 6) in which the angle defined by any two
adjacent surfaces, from among these annular surfaces, is the same
(angle .theta. in FIG. 7).
[0136] Moreover, in the ports according to the embodiments, the
valve seat portion 31a has a plurality of annular surfaces (three
or more annular surfaces; for example, four annular surfaces) in
which the width of each of the plurality of annular surfaces is the
same (width w in FIG. 8).
[0137] In the ports according to the embodiments, the valve seat
portion 31a has four annular surfaces (see FIG. 6).
[0138] Furthermore, the ports according to the embodiments are such
that the throat portion 31b is connected to the passage portion 31c
such that the flow direction of gas that flows along the peripheral
surface of the throat portion 31b is parallel to the generating
line 31bgen of the truncated cone shape 31b1 of the throat portion
31b when gas passes through the throat portion 31b.
[0139] That is, for example, the port of the invention is such that
the throat portion 31b is connected to the passage portion 31c such
that the axis E of the throat portion 31b and the axis F of the
passage portion 31c are in the same plane.
[0140] Moreover, in the ports according to the embodiments, the
throat portion 31b is connected to the passage portion 31c such
that at least a portion of the generating line extension line
31bext that is an extension line of the generating line 31bgen of
the truncated cone shape 31b1 of the throat portion 31b is included
in the peripheral surface 31cper that includes the boundary line
31bcbo between the passage portion 31c and the throat portion 31b,
and that is a peripheral surface of the passage portion 31c.
Other Modes
[0141] The invention is not limited to the embodiments described
above. That is, various modified examples may also be employed
within the scope of the invention.
[0142] For example, the ports according to the embodiments
described above are applied to the spark-ignition internal
combustion engine 10. However, the port of the invention may also
be applied to an engine other than a spark-ignition engine (such as
a diesel engine).
[0143] Furthermore, in the embodiments described above, the port is
applied to the intake port 31. However, the port of the invention
may also be applied to an exhaust port.
[0144] In addition, in the embodiments described above, the valve
seat portion 31a of the intake port 31 has four annular surfaces.
However, the number of annular surfaces of the valve seat portion
is not particularly limited as long as it is set to a suitable
value that takes into account the ability to block off gas in the
port and the cost for forming the valve seat portion and the
like.
[0145] Moreover, in the embodiments described above, the passage
portion 31c has a round columnar shape. However, the passage
portion 31c may have a square columnar shape or an elliptical
columnar shape or the like.
[0146] Further, in the embodiments described above, the throat
portion 31b has the truncated cone-shaped portion 31b1. However,
the throat portion may be configured to have a complete truncated
cone shape.
[0147] Also, in the embodiments described above, the plurality of
annular surfaces (31a1 to 31a4) that make up the valve seat portion
31a are configured to be rings formed by closed bands having flat
surfaces. However, the plurality of annular surfaces may also be
rings formed by closed bands having curved surfaces. Also, if rings
formed by closed bands having curved surfaces are used as the
annular surfaces, the curvature radius of the curved surfaces may
be set such that another curved surface is formed by a portion or
all of the plurality of annular surfaces.
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