U.S. patent application number 11/175433 was filed with the patent office on 2006-02-23 for airflow control valve for use in an internal combustion engine.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Satoshi Ishigaki, Masaki Sakata.
Application Number | 20060037310 11/175433 |
Document ID | / |
Family ID | 35721789 |
Filed Date | 2006-02-23 |
United States Patent
Application |
20060037310 |
Kind Code |
A1 |
Sakata; Masaki ; et
al. |
February 23, 2006 |
Airflow control valve for use in an internal combustion engine
Abstract
An airflow control valve is composed of a housing forming an air
passage therein and an electromagnetically driven valve disposed in
the air passage. The valve divides the air passage into an upstream
passage having an air inlet port and a downstream passage having an
outlet port open to an exhaust pipe. A barrier facing an exhaust
gas blown back from the exhaust pipe is formed in the downstream
passage in order to reduce an amount of deposits accumulating on
and around the valve due to foreign particles contained in the
exhaust gas. The barrier may be a dead end space in which the
exhaust gas stagnates or a wall interfering with a flow of the
exhaust gas. A one-way valve may be disposed immediately downstream
of the valve to prevent the exhaust gas from flowing toward the
valve.
Inventors: |
Sakata; Masaki;
(Kariya-city, JP) ; Ishigaki; Satoshi;
(Takahama-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
35721789 |
Appl. No.: |
11/175433 |
Filed: |
July 7, 2005 |
Current U.S.
Class: |
60/289 |
Current CPC
Class: |
Y02T 10/20 20130101;
F01N 3/30 20130101; Y02T 10/12 20130101 |
Class at
Publication: |
060/289 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 20, 2004 |
JP |
2004-240955 |
Claims
1. An airflow control valve for use in an internal combustion
engine, the airflow control valve comprising: a housing forming an
air passage therein; a valve disposed in the air passage for
opening or closing the air passage, the air passage being separated
by the valve into an upstream passage having an inlet port and a
downstream passage having an outlet port from which air is blown
out, the outlet port being open to a source of exhaust gas
exhausted from the internal combustion engine; and a barrier
disposed in the down stream passage to face the outlet port for
reducing an amount of the exhaust gas directly hitting the valve
when the exhaust gas enters the downstream passage from the outlet
port.
2. The airflow control valve as in claim 1, wherein: the barrier
includes a passage surface facing the outlet port; and a stagnating
space for stagnating the exhaust gas flow is formed in the vicinity
of the passage surface.
3. An airflow control valve for use in an internal combustion
engine, the airflow control valve comprising: a housing forming an
air passage therein; a valve disposed in the air passage for
opening or closing the air passage, the air passage being separated
by the valve into an upstream passage having an inlet port and a
downstream passage having an outlet port from which air is blown
out, the outlet port being open to a source of exhaust gas
exhausted from the internal combustion engine; and a dead end space
disposed in the downstream passage to face the outlet port for
stagnating the exhaust gas entering into the downstream passage
from the outlet port, the dead end space having an opening from
which the exhaust gas enters.
4. The airflow control valve as in claim 3, wherein: the dead end
space includes a passage surface facing the outlet port, and the
opening of the dead end space open to the passage surface.
5. The airflow control valve as in claim 3, wherein: the opening of
the dead end space is smaller than an inside of the dead end
space.
6. The airflow control valve as in claim 3, wherein: a bent portion
for preventing foreign particles, contained in the exhaust gas,
once entered into the dead end space from bouncing out of the dead
end space is formed at the opening of the dead end space.
7. The airflow control valve as in claim 6, wherein: the bent
portion is formed at a portion of the opening close to the
valve.
8. An airflow control valve for use in an internal combustion
engine, the airflow control valve comprising: a housing forming an
air passage therein; a valve disposed in the air passage for
opening or closing the air passage, the air passage being separated
by the valve into an upstream passage having an inlet port and a
downstream passage having an outlet port from which air is blown
out, the outlet port being open to a source of exhaust gas
exhausted from the internal combustion engine; and an interfering
wall disposed in the downstream passage for interfering with a flow
of the exhaust gas entering into the downstream passage from the
outlet port.
9. The airflow control valve as in claim 8, wherein: the
interfering wall includes a wall surface directly facing the outlet
port; and a stagnating space for stagnating the exhaust gas therein
is formed between the wall surface and the outlet port.
10. The airflow control valve as in claim 9, wherein: the
downstream passage includes passage surfaces inclined along a flow
direction of the air to be blown out from the outlet port so that
the air smoothly flows through the downstream passage.
11. The airflow control valve as in claim 1, wherein: the upstream
passage is a passage for introducing compressed secondary air to be
supplied to an exhaust pipe of the internal combustion engine; the
downstream passage is a passage for supplying the air to the
exhaust pipe of internal combustion engine; and the valve is a
valve for controlling an amount of the secondary air to be supplied
to the exhaust pipe of the engine by opening or closing the air
passage.
12. The airflow control valve as in claim 11, wherein: a one-way
valve for preventing the exhaust gas from entering into the
upstream passage is provided in the downstream passage.
13. The airflow control valve as in claim 12, wherein: the one-way
valve includes a metal plate having air passages through which the
secondary air flows, a reed valve for opening or closing the air
passages, and a reed valve stopper for limiting an opening degree
of the reed valve; and the one-way valve is positioned in the
vicinity of the valve.
14. The airflow control valve as in claim 1, wherein: the air
passage is a passage for connecting an exhaust pipe to an intake
pipe of the internal combustion engine for re-circulating part of
the exhaust gas to the engine for decreasing a combustion
temperature in the engine, and an amount of the exhaust gas to be
re-circulated is controlled by the valve.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims benefit of
priority of Japanese Patent Application No. 2004-240955 filed on
Aug. 20, 2004, the content of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an airflow control valve
for opening or closing an air passage communicating with an exhaust
gas passage in an internal combustion engine, and more particularly
to an airflow control valve for controlling an amount of secondary
air supplied from an air pump to an exhaust pipe.
[0004] 2. Description of Related Art
[0005] Examples of an airflow control valve for supplying secondary
air to a three-way catalyzer in an exhaust pipe for raising
temperature of the three-way catalyzer when an engine is being
started are disclosed in JP-A-2002-272080 and JP-A-2002-260919. The
airflow control valve disclosed therein includes an electromagnetic
valve and a one-way valve. An essential portion of the airflow
control valve is shown in FIG. 10 attached hereto.
[0006] As shown in FIG. 10, the electromagnetic valve 102 contained
in a valve housing 104 is composed of a valve 106 for opening or
closing an opening 105 formed in the valve housing, a solenoid
actuator for driving the valve 106 in a direction to open the
opening 105, and a coil spring 107 for biasing the valve 106 in a
direction to close the opening 105. The one-way valve 103 is
disposed at a boundary portion connecting the valve housing 104 and
an outlet casing 110. The one-way valve 103 is composed of a reed
valve 112 for opening or closing an opening 111 formed in a metal
plate 114 and a reed stopper 113 for protecting the reed valve
112.
[0007] Air pressurized by an air pump (not shown) is introduced
into the valve housing 104, and the introduced air is supplied to a
three-way catalyzer (not shown) in an exhaust pipe through an air
passage shown with white arrows when the valve 106 opens the
opening 105. The one-way valve 103 is opened by the air passing
through the air passage and is closed by exhaust gas (shown with
dotted arrows in FIG. 10) blown back from the exhaust pipe. The
blown back exhaust gas that includes unburned gas, carbon particles
and other small particles is prevented from entering into the valve
housing 104 by the one-way valve 103.
[0008] In the conventional airflow control valve, however,
following problems are involved. When the valve 106 is closed,
exhaust gas is blown back due to pulsating pressure of the engine
and enters into the outlet casing 110 as shown with dotted arrows
in FIG. 10. Small particles contained in the exhaust gas adhere to
the reed valve 112, forming deposits thereon. If the deposits are
formed between the metal plate 114 and the reed valve 112, the reed
valve 112 becomes unable to close, and the exhaust gas enters into
valve housing 104 containing the valve 106 therein. In other words,
the reed valve 112 becomes unable to function as the one-way valve
for preventing the exhaust gas from being blown back into the valve
housing 104. The deposits may be formed on the valve 106 and the
valve seat. If this happens, movement of the valve 106 is hindered,
and the valve 106 may not be smoothly opened. As a result, the
secondary air cannot be sufficiently supplied to the three-way
catalyzer.
[0009] An exhaust gas control valve is conventionally used in an
exhaust gas re-circulation system. In this system, part of the
exhaust gas is introduced into an air-intake pipe of an engine to
reduce an amount of nitrogen-oxides formulated in combustion by
lowering a combustion temperature. The re-circulating exhaust gas
is supplied to the intake pipe through the exhaust gas control
valve. The exhaust gas control valve is composed of a housing
forming an exhaust gas passage therein, a valve for closing or
opening the exhaust gas passage, and a coil spring biasing the
valve in the closing direction. The valve is driven by a motor
actuator in the opening direction.
[0010] Small particles contained in the exhaust gas adhere to the
valve and the valve seat in the exhaust gas control valve, forming
deposits around the valve. To reduce an amount of deposits
accumulated around the valve, an exhaust gas recirculation valve
having a side hole in the passage for accumulating the deposits
therein is proposed in JP-A-2002-339811. However, the small
particles in the exhaust gas once entered into the side hole are
highly possible to bounce out into the passage. Therefore, much
effect cannot be expected for the proposed side hole.
SUMMARY OF THE INVENTION
[0011] The present invention has been made in view of the
above-mentioned problem, and an object of the present invention is
to provide an improved airflow control valve, in which an amount of
deposits accumulating on a control valve and a one-way valve is
reduced.
[0012] The airflow control valve has an air passage and an
electromagnetically driven valve disposed in the air passage. The
air passage is divided into two passages by the valve, i.e., an
upstream passage having an inlet port and a downstream passage
having an outlet port. Secondary air compressed by an air pump is
introduced into the upstream passage through the inlet port and
supplied from the downstream passage to an exhaust pipe of an
internal combustion engine through the outlet port. An amount of
air supplied to the exhaust pipe is controlled by opening or
closing the valve. The outlet port is open to the exhaust pipe, and
exhaust gas is blown back into the downstream passage.
[0013] A barrier facing the outlet port from which the exhaust gas
enters into the airflow control valve is disposed in the downstream
passage to reduce an amount of the exhaust gas directly hitting the
valve. Thus, an amount of deposits accumulating on and around the
valve due to foreign particles contained in the exhaust gas is
reduced. The barrier may be made in a form of a dead end space
having a small opening facing the outlet port. The exhaust gas
entering into the airflow control valve stagnates in the dead end
space, and some foreign particles are kept therein. To prevent the
foreign particles once kept in the dead end space from bouncing out
of the dead end space toward the valve, bent portions may be made
at the opening of the dead end space. An interfering wall directly
facing the outlet port may be made in the downstream passage to
form a stagnating space between the interfering wall and the outlet
port.
[0014] Preferably, one-way valve for preventing the exhaust gas
from entering into the upstream passage while permitting the
secondary air to flow therethrough is disposed immediately
downstream of the valve. The valve is prevented from being directly
hit by the exhaust gas blown back from the exhaust pipe. The
one-way valve is also protected from being directly hit by a large
amount of the exhaust gas by the barrier, the dead end space or the
interfering wall disposed in the downstream passage.
[0015] The airflow control valve may be used as a valve for
controlling an amount of exhaust gas to be re-circulated from an
exhaust pipe into an intake pipe of an engine. In this case, the
exhaust gas is introduced from the outlet port, and the inlet port
is connected to the intake pipe of the engine.
[0016] According to the present invention, an amount of exhaust gas
directly hitting the valve and the one-way valve is reduced and an
amount of deposits accumulating on and around the valve and the
one-way valve is reduced. Accordingly, the airflow control valve
can be operated without being hindered by accumulation of deposits.
Other objects and features of the present invention will become
more readily apparent from a better understanding of the preferred
embodiments described below with reference to the following
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a cross-sectional view showing an airflow control
valve as a first embodiment of the present invention;
[0018] FIG. 2 is a cross-sectional view showing the same airflow
control valve as shown in FIG. 1, including arrows showing flow
directions of air and exhaust gas;
[0019] FIG. 3 is a cross-sectional view showing an airflow control
valve as a second embodiment of the present invention;
[0020] FIG. 4 is a cross-sectional view showing an airflow control
valve as a third embodiment of the present invention;
[0021] FIG. 5 is a cross-sectional view showing an airflow control
valve as a fourth embodiment of the present invention;
[0022] FIG. 6 is a plan view showing an outlet casing used in the
fourth embodiment shown in FIG. 5;
[0023] FIG. 7 is a cross-sectional view showing the same airflow
control valve as shown in FIG. 5, including arrows showing flow
directions of air and exhaust gas;
[0024] FIG. 8A is a plan view showing an outlet casing used in the
airflow control valve shown in FIG. 5, viewed from its topside;
[0025] FIG. 8B is a plan view showing a modified form of the outlet
casing shown in FIG. 8A;
[0026] FIG. 9 is a plan view showing the same outlet casing as
shown in FIG. 8B, in an enlarged scale; and
[0027] FIG. 10 is a cross-sectional view showing a conventional
airflow control valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] A first embodiment of the present invention will be
described with reference to FIGS. 1 and 2. In this embodiment, a
stagnating space in which exhaust gas blown back from an exhaust
pipe stagnates is provided in an outlet casing of an airflow
control valve in order to reduce accumulation of deposits on a
control valve. The airflow control valve is disposed in an air
passage for supplying secondary air to a three-way catalyzer in an
exhaust pipe. The secondary air is sent from a motor-driven air
pump to the airflow control valve that includes an electromagnetic
valve for controlling an amount of the secondary air supplied to
the three-way catalyzer. Operation of the motor for driving the air
pump and the electromagnetic valve is controlled by an electronic
control unit (ECU). The secondary air is supplied to the three-way
catalyzer to activate the catalyzer when an engine is being started
and an exhaust gas temperature is low.
[0029] As shown in FIG. 1, the airflow control valve is composed of
a valve housing 3 containing an electromagnetic valve 1 having a
poppet-type valve 2 therein, an outlet casing 9 having a one-way
valve 6 and other associated components. An air passage (11, 12,
14, 16, 17) for supplying the secondary air to the three-way
catalyzer is formed in the valve housing 3 and the outlet casing
9.
[0030] The electromagnetic valve 1 includes the poppet-type valve
2, a solenoid actuator 4 for driving the valve 2 in the opening
direction and a coil spring 5 for biasing the valve 2 in the
closing direction. The valve 2 is formed in a disc shape having a
resilient rubber ring disposed around its outer periphery. The
valve 2 is connected to a valve shaft 21 that is reciprocated in
the vertical direction. The valve 2 is seated on a valve seat 23
formed on a valve sheet frame 22 of the valve housing 3 to close an
opening 13. When the valve 2 is driven, the valve 2 is lifted from
the valve seat 23 to open the opening 13. The valve shaft 21 is
slidably inserted into a sleeve 25, and a seal rubber 24 is
disposed to close a small sliding gap between the sleeve 25 and the
valve shaft 21 to thereby prevent small particles from entering
into the sliding gap.
[0031] The valve housing 3 is made of aluminum by die-casting, and
includes a inner space for accommodating the solenoid actuator 4
and a connecting pipe 26 having an inlet port 10 for introducing
the secondary air supplied from the air pump. The outlet casing 9
is also made of aluminum by die-casting, and includes air passages
16, 17, an outlet port 18 to be connected to the exhaust pipe and a
dead end space 19 (described later in detail). An upper end of the
outlet casing 9 is connected to a flange 39 formed at a lower end
of the valve housing 3, and a one-way valve 6 is positioned at the
upper end portion of the outlet casing 9. A circular seal rubber 37
is disposed between the valve housing 3 and the outlet casing 9 for
hermetically seal the connecting portion. The air passage formed in
the valve housing 3 and the outlet casing 9 is separated by the
valve 2 into an upstream passage 11, 12 and a downstream passage
14, 16, 17.
[0032] The solenoid actuator 4 for driving the valve 2 is composed
of a solenoid coil 28 wound around a coil bobbin 27, a pair of
terminals 29 for supplying electric power to the solenoid coil 28,
a housing cover 30 supporting the terminals 29, a cylindrical yoke
31, a cylindrical stator core 32 connected to the yoke 31 forming a
space for accommodating the solenoid coil 28 therebetween, and a
moving core 33 connected to the valve shaft 21. The coil bobbin 27
is made of a resin material such as polybutylene terephthalate
(PBT) and fixedly positioned in a cylindrical space between the
yoke 31 and the stator core 32.
[0033] Upon supplying electric power to the solenoid coil 28 from
the terminals 29, the moving core 33 connected to the valve shaft
21 is driven downward by magnetic field generated in the yoke 31
and the stator core 32 thereby to open the valve 12 against the
biasing force of the coil spring 5. The terminals 29 are connected
to the ECU through a wire harness, and the operation of the
electromagnetic valve 1 is controlled by the ECU.
[0034] At the bottom end of the stator core 32, a flange portion
forming the air passage 12 is provided, and at a center portion of
the stator core 32, a thin wall portion 35 is formed to provide a
high magnetic resistance in the magnetic circuit. The moving core
33 moves downward to open the valve 2 when the magnetic field is
generated by the solenoid coil 28. The valve shaft 21 is inserted
into a center hole of the moving core 33 and a center hole of a
washer 36 so that a step formed on the valve shaft 21 abuts the
bottom end of the moving core 33, and the upper end of the valve
shaft 21 is staked to fixedly connect the valve shaft 21 to the
moving core 33. The coil spring 5 is disposed outside of the sleeve
25, and its upper end is connected to the bottom of the moving core
33 and its lower end is connected to a flange portion of the sleeve
25, so that a biasing force of the coil spring 5 is given to the
valve 2 in the closing direction.
[0035] The one-way valve 6 is a valve for preventing the exhaust
gas blown back from the exhaust pipe from entering into the valve
housing 3 while allowing the secondary air to flow therethrough.
The one-way valve 6 is composed of a metal plate 41 that has plural
openings 15, a reed valve 7 for opening or closing the openings 15,
and a reed valve stopper 8 for limiting the reed valve 7 at its
maximum open position. The metal plate 41 is made of a metallic
material such as aluminum and includes plural openings 15 formed in
a mesh-like shape. The reed valve 7 is made of a metallic material
such as a spring plate. One end of the reed valve 7 is supported on
the metal plate 41 with screws 42 or the like, and the other end of
the reed valve 7 is shaped in double tongues or triple tongues. On
the surface of the mesh-like openings 15 of the metal plate 41, a
rubber seal is formed by baking. The reed stopper 8 is made of a
metallic material. One end of the reed stopper 8 is connected to
the metal plate 41, and the other end thereof is a free end having
double or triple tongues.
[0036] Now, the structure of the outlet casing 9 having the dead
end space 19 will be described in detail. The exhaust gas may be
blown back from the exhaust pipe into the air passage 16, 17
through the outlet 18 due to a pressure pulsation generated in the
exhaust pipe. The exhaust gas includes small particles consisting
of unburned gas, carbon particles or the like. These small
particles accumulate on the reed valve 7 forming deposits thereon.
When the deposits are formed on the reed valve 7, the reed valve 7
may become impossible to close to prevent the exhaust gas from
entering into the valve housing 3. To decrease the amount of
exhaust gas hitting the reed valve 7, barrier 51 is formed so that
a passage surface 52 of the barrier 51 faces the outlet 18.
[0037] A dead end space 19 is formed inside of the barrier 51. One
end of the dead end space 19 is an opening 54 facing the outlet 18,
and the other end thereof is closed with a hermetic plug 53. A
center line of the head end space 19 is substantially directed to a
center line of the outlet port 18. The dead end space 19 is
positioned in the downstream passage, i.e., downstream of the valve
2 and the one-way valve 6. The dead end space 19 functions as a
stagnating space in which the blown back exhaust gas stagnates,
thereby reducing an amount of the exhaust gas directly hitting the
reed valve 7. The dead end space 19 is positioned at a far most
position from the electromagnetic valve 1 to suppress a temperature
rise due to the exhaust gas in a space around the electromagnetic
valve 1.
[0038] The barrier 51 includes a bent portion 55 for preventing
foreign particles once entered into the dead end space 19 from
bouncing out again into the air passage 16. The bent portion 55 is
bent downwardly so that the opening 54 becomes narrower than an
inside space of the dead end space 19. A curved surface 57 is
formed above the dead end space 19. The curved surface 57
facilitates a smooth flow of the secondary air flowing out through
the plural openings 15 of the metal plate 41.
[0039] Now, operation of the airflow control valve described above
will be explained. A three-way catalyzer for converting CO, HC and
NOx contained in the exhaust gas into harmless components is
installed in an exhaust pipe of an automobile. To realize a good
conversion reaction in the three-way catalyzer, it is required to
keep air-fuel mixture supplied to an internal combustion engine at
a stoichiometric ratio (15:1) and to raise the exhaust gas
temperature above a certain level, e.g., 350.degree. C. When the
exhaust gas temperature is low, e.g., when the engine is being
started, secondary air is supplied from an air pump to the
three-way catalyzer to raise its temperature. By supplying air to
the three-way catalyzer, the catalyzer is activated by heat
generated by burning hydrocarbons contained in the exhaust gas.
[0040] The secondary air is supplied from the air pump to the
three-way catalyzer through the airflow control valve. When the
secondary air is required, the valve 2 is opened under the control
of the ECU, and the secondary air is sent through the upstream
passage 11, 12, the opening 13, the passage 14, the opening 15 and
the downstream passage 16, 17, as shown with white arrows in FIG.
2. In this case, the one-way valve 6 is opened by the pressure of
the secondary air. The secondary air smoothly flows along the
curved surface 57 toward the outlet port 18. Thus, the three-way
catalyzer is activated to convert harmful components in the exhaust
gas into harmless components.
[0041] When the valve 2 is closed, the blown back exhaust gas
enters into the air passage 16, 17. Particles contained in the
exhaust gas form deposits on and around the reed valve 7 of the
one-way valve 6. When a certain amount of the deposits is
accumulated on and around the reed valve 7, the reed valve 7
becomes unable to close. If the one-way valve 6 does not function
as a one-way valve, the exhaust gas entered the air passage 16
further proceeds to the air passage 14 through the opening 15 of
the one-way valve 6. If this happens, it is highly possible that
deposits are formed on and around the valve 2, making the valve 2
unable to work properly. If the valve 2 does not work properly, a
sufficient amount of the secondary air will not be supplied to the
three-way catalyzer.
[0042] In order to avoid the trouble mentioned above, the dead end
space 19 is formed in the outlet casing 9 according to the present
invention. As shown in FIG. 2 with dotted arrows, the exhaust gas
blown back from the exhaust pipe enters into the air passage 16, 17
along a bottom wall 56 and proceeds to the dead end space 19
through the opening 54. The exhaust gas entered into the dead end
space 19 hits the wall of the dead end space 19 and stagnates
therein. Therefore, an amount of the exhaust gas directly hitting
the one-way valve 6 is reduced. Accordingly, formation of the
deposits on and around the reed valve 7 is suppressed. Further, the
opening 54 of the dead end space 19 is made narrower than the
inside space, and the bent portion 55 is formed at the opening 54.
Therefore, the exhaust gas once entered into the dead end space
circulates therein, keeping the foreign particles contained in the
exhaust gas in the dead end space.
[0043] Thus, formation of the deposits on and around the one-way
valve 6 and the valve 2 is suppressed, thereby securing proper
operation of the airflow control valve. Further, since the dead end
space 19 is formed at the position far from the valve 2, a
temperature rise in the electromagnetic valve 1 due to the exhaust
gas is suppressed. Since the curved surface 57 is formed above the
dead end space 19, the secondary air smoothly flows through the air
passage 16, 17 when the valve 2 is opened. The foreign particles
accumulated in the dead end space 19 when the valve 2 is closed are
sucked back again into the exhaust pipe together with the secondary
air when the valve 2 is opened. Accordingly, it is not necessary to
provide a dead end space 19 with a large size or to provide
additional means for scavenging the dead end space 19.
[0044] A second embodiment of the present invention will be
described with reference to FIG. 3. In this embodiment, a shape of
the barrier 51 in the first embodiment is modified to a barrier 51a
shown in FIG. 3. The barrier 51a includes a passage surface 52a
standing up from the bottom wall 56 at a right angle. A stagnating
space 59 is formed between the air passage 17 and the passage
surface 52a.
[0045] The exhaust gas blown back from the exhaust pipe and
entering into the outlet casing 9 from the outlet port 18 hits the
passage surface 52a. An amount of exhaust gas directly hitting the
one-way valve 6 is reduced, and the exhaust gas stagnates in the
stagnating space 59. Foreign particles included in the exhaust gas
form deposits in the stagnating space 59 or accumulates therein.
Thus, an amount of deposits formed on and around the reed valve 7
is reduced. In this manner, the barrier 51a in the second
embodiment functions similarly to the barrier 51 in the first
embodiment.
[0046] A third embodiment of the present invention is shown in FIG.
4. In this embodiment, a barrier 51b is further modified from the
barrier 51a of the second embodiment. The barrier 51b includes a
passage surface 52b standing up from the bottom wall 56 forming an
acute angle. A stagnating space 59b is formed between the air
passage 17 and the passage surface 52b. The amount of exhaust gas
directly hitting the one-way valve 6 is reduced in the same manner
as in the second embodiment. Further, in this third embodiment, the
foreign particles in the exhaust gas once kept in the stagnating
space 59b are prevented from bouncing out of the stagnating space
59b by the passage surface 52b forming an acute angle between
itself and the bottom wall 56.
[0047] A fourth embodiment of the present invention will be
described with reference to FIGS. 5-9. In this embodiment, as shown
in FIGS. 5 and 6, an interfering wall 61 standing up from the
bottom wall 56 at a right angle is formed in the inner space of the
outlet casing 9. The interfering wall 61 has a wall surface 62
directly facing the outlet port 18, and a stagnating space 64 is
formed between the air passage 17 and the wall surface 62. As shown
in FIG. 6 the interfering wall 61 further includes a pair of bent
portions 63 bent toward the outlet port 18. Further, passage
surfaces 66 having an inclination as shown in FIG. 6 are formed on
an inner wall of the outlet casing 9 for smoothly guiding the
secondary airflow sent through the valve 2 to the outlet 18. An air
passage 67 converging to the outlet port 18 is formed by the
passage surfaces 66. Holes 43 (shown in FIG. 6) are holes for
connecting the outlet casing 9 to the valve housing 3 with screws
or the like.
[0048] As shown in FIGS. 7 and 8A (an exhaust gas flow is shown
with dotted arrows and a secondary airflow is shown with white
arrows), the exhaust gas entering into the air passage 17 from the
outlet port 18 hits the interfering wall 61 and stagnates in the
stagnating space 64. A certain amount of foreign particles included
in the exhaust gas is kept in the stagnating space 64, and an
amount of exhaust gas hitting the one-way valve 6 is reduced. The
foreign particles once kept in the stagnating space 64 are
prevented from bouncing out of the stagnating space 64 toward the
one-way valve 6 by the pair of bent portions 63. In this manner, an
amount of deposits formed on and around the reed valve 7 is
reduced.
[0049] The interfering wall 61 could be an obstacle to the
secondary airflow supplied from the air pump through the valve 2.
To avoid the interfering wall 61 from becoming an obstacle to the
secondary airflow, as shown in FIG. 8A, the inclined passage
surfaces 66 are formed on the inner wall of the outlet casing 9,
and inclined surfaces 65 along the secondary airflow are formed on
the bent portions 63. A smooth air passage 67 for the secondary
airflow is formed by the inclined passage surfaces 65, 66.
Therefore, the secondary air smoothly flows through the air passage
67 without generating a high amount of pressure loss.
[0050] The outlet casing 9 in the fourth embodiment may be further
modified to a form shown in FIGS. 8B and 9. In this modified form,
a barrier 71 is formed in the outlet casing 9. The barrier 71
includes a passage surface 72 directly facing the outlet 18 so that
the exhaust gas entering into the outlet casing 9 hits the passage
surface 72. The passage surface 72 stands up from the bottom wall
56 at a right angle, and a stagnating space 74 is formed between
the barrier 71 and the outlet port 18. Bent portions 73 for
preventing the foreign particles once trapped in the stagnating
space 74 from easily bouncing out of the stagnating space 74 are
formed on the passage surface 72. Further, inclined passage
surfaces 75 for smoothly guiding the airflow 76 of the secondary
air toward the outlet port 18 are formed.
[0051] The exhaust gas entering into the air passage 17 from the
outlet port 18 hits the passage wall 72 and stagnates in the
stagnating space 74. Foreign particles in the exhaust gas are
accumulated or deposited in the stagnating space 74. An amount of
the exhaust gas directly hitting the one-way valve 6 is reduced,
and an amount of foreign particles deposited on and around the reed
valve 7 is reduced. The secondary air supplied from the air pump
through the valve 2 is smoothly led to the outlet port 18 along the
inclined passage walls 75.
[0052] The present invention is not limited to the embodiments
described above, but it may be variously modified. The barrier
and/or the stagnating space for the exhaust gas according to the
present invention may be applied to various valves such as a swirl
control valve, an intake-air control valve in a swirl control
valve, a tumble control valve, an intake-air control valve in a
tumble control valve, or a throttle valve for controlling amount of
intake-air. The present invention may be applied also to an exhaust
gas re-circulating valve for supplying a certain amount of exhaust
gas into an air-intake pipe of an internal combustion engine.
[0053] While the present invention has been shown and described
with reference to the foregoing preferred embodiments, it will be
apparent to those skilled in the art that changes in form and
detail may be made therein without departing from the scope of the
invention as defined in the appended claims.
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