U.S. patent application number 13/053930 was filed with the patent office on 2011-09-29 for internal combustion engine exhaust cooling system.
This patent application is currently assigned to Toyota Jidosha Kabushiki Kaisha. Invention is credited to Fujio Inoue, Shinichi Mitani, Tetsuji Watanabe.
Application Number | 20110232275 13/053930 |
Document ID | / |
Family ID | 44654781 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110232275 |
Kind Code |
A1 |
Watanabe; Tetsuji ; et
al. |
September 29, 2011 |
INTERNAL COMBUSTION ENGINE EXHAUST COOLING SYSTEM
Abstract
An internal combustion engine exhaust cooling system includes an
exhaust gas cooling adapter that is arranged between an exhaust
port that opens in a cylinder head, and an exhaust branch pipe, and
cools exhaust gas that flows through an exhaust passage by running
coolant through a coolant passage formed inside of a wall that
surrounds the exhaust passage. The coolant passage includes a first
passage and a second passage being provided according to an offset
of an amount of heat received from exhaust gas in a circumferential
direction of an inner surface of the exhaust passage, and two
middle passages that connect the first passage with the second
passage at both ends of the two middle passages, and a coolant
delivery direction is a direction from the second passage side of a
first middle passage, of the two middle passages, toward the first
passage side.
Inventors: |
Watanabe; Tetsuji;
(Toyota-shi, JP) ; Mitani; Shinichi; (Susono-shi,
JP) ; Inoue; Fujio; (Tokyo, JP) |
Assignee: |
Toyota Jidosha Kabushiki
Kaisha
Toyota-Shi
JP
|
Family ID: |
44654781 |
Appl. No.: |
13/053930 |
Filed: |
March 22, 2011 |
Current U.S.
Class: |
60/321 |
Current CPC
Class: |
F01P 2060/16 20130101;
F01P 3/12 20130101 |
Class at
Publication: |
60/321 |
International
Class: |
F01N 3/02 20060101
F01N003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2010 |
JP |
JP2010-066974 |
Claims
1. An internal combustion engine exhaust cooling system comprising:
an exhaust gas cooling adapter that is arranged between an exhaust
port that opens in a cylinder head, and an exhaust branch pipe, and
cools exhaust gas that flows through an exhaust passage by running
coolant through a coolant passage formed inside of a wall that
surrounds the exhaust passage, wherein the exhaust gas cooling
adapter includes a coolant inlet that introduces coolant into the
coolant passage, and a coolant outlet that discharges coolant
outside from the coolant passage; the coolant passage includes a
first passage that is on a high heat receiving side and a second
passage that is on a low heat receiving side, the first passage and
the second passage being provided according to an offset of an
amount of heat received from exhaust gas in a circumferential
direction of an inner surface of the exhaust passage, and two
middle passages that connect the first passage with the second
passage at both ends of the two middle passages; a coolant delivery
direction of the coolant inlet is a direction from the second
passage side of a first middle passage, of the two middle passages,
toward the first passage side; and the coolant outlet discharges
coolant from a location where a second middle passage, of the two
middle passages, is connected with the first passage, or from near
the location.
2. The internal combustion engine exhaust cooling system according
to claim 1, wherein the first middle passage is located closer to
the coolant inlet than the second middle passage is.
3. The internal combustion engine exhaust cooling system according
to claim 1, wherein the coolant outlet discharges coolant in the
same direction as a flow direction of coolant in the first
passage.
4. The internal combustion engine exhaust cooling system according
to claim 1, wherein a plurality of the exhaust ports are provided;
each of the plurality of exhaust ports is arranged and open in a
cylinder head; a plurality of the exhaust passages are formed in an
arrangement inside the exhaust gas cooling adapter, the arrangement
of the plurality of exhaust passages corresponding to an
arrangement of the plurality of exhaust ports; and the exhaust
ports are formed curved in a direction orthogonal to an arrangement
direction of the exhaust passages, or the exhaust ports and the
exhaust passages are connected bent in a direction orthogonal to
the arrangement direction.
5. The internal combustion engine exhaust cooling system according
to claim 4, wherein the arrangement direction of the exhaust ports
in the cylinder head is a horizontal direction, and the direction
orthogonal to the arrangement direction is vertically downward.
6. The internal combustion engine exhaust cooling system according
to claim 1, wherein a plurality of the exhaust ports are provided;
each of the plurality of exhaust ports is arranged and open in a
cylinder head; a plurality of the exhaust passages are formed in an
arrangement inside the exhaust gas cooling adapter, the arrangement
of the plurality of exhaust passages corresponding to an
arrangement of the plurality of exhaust ports; the exhaust ports
are formed curved in a direction orthogonal to an arrangement
direction of the exhaust passages, or the exhaust ports and the
exhaust passages are connected bent in a direction orthogonal to
the arrangement direction; the coolant inlet delivers coolant from
the second passage toward the first passage via a middle passage on
one end side in the arrangement direction; and the coolant outlet
discharges coolant from a location where a middle passage on the
other end side in the arrangement direction is connected to the
first passage, or from near the location.
7. The internal combustion engine exhaust cooling system according
to claim 1, wherein a flow direction guide that guides a flow of
coolant delivered from the coolant inlet to a first middle passage,
of the two middle passages, is provided in the coolant passage, in
a location near the coolant inlet.
8. An internal combustion engine exhaust cooling system comprising:
an exhaust gas cooling adapter that is arranged between an exhaust
port that opens in a cylinder head, and an exhaust branch pipe, and
cools exhaust gas that flows through an exhaust passage by running
coolant through a coolant passage formed inside of a wall that
surrounds the exhaust passage, wherein the exhaust gas cooling
adapter includes a coolant inlet that introduces coolant into the
coolant passage, and a coolant outlet that discharges coolant
outside from the coolant passage; the coolant passage includes an
outside passage of a curve and an inside passage of a curve that
are provided according to a curve in an exhaust flow produced by a
curved shape of the exhaust port, and two middle passages that
connect the outside passage with the inside passage at both ends of
the two middle passages; a coolant delivery direction of the
coolant inlet is a direction from the inside passage side of a
first middle passage, of the two middle passages, toward the
outside passage side; and the coolant outlet discharges coolant
from a location where a second middle passage, of the two middle
passages, is connected with the outside passage, or from near the
location.
9. The internal combustion engine exhaust cooling system according
to claim 8, wherein the first middle passage is located closer to
the coolant inlet than the second middle passage.
10. The internal combustion engine exhaust cooling system according
to claim 8, wherein the exhaust passage is bent with respect to the
exhaust port.
11. The internal combustion engine exhaust cooling system according
to claim 8, wherein the coolant outlet discharges coolant in the
same direction as a flow direction of coolant in the outside
passage.
12. The internal combustion engine exhaust cooling system according
to claim 8, wherein a plurality of the exhaust ports are provided;
each of the plurality of exhaust ports is arranged and open in a
cylinder head; a plurality of the exhaust passages are formed in an
arrangement inside the exhaust gas cooling adapter, the arrangement
of the plurality of exhaust passages corresponding to an
arrangement of the plurality of exhaust ports; and the exhaust
ports are formed curved in a direction orthogonal to an arrangement
direction of the exhaust passages, or the exhaust ports and the
exhaust passages are connected bent in a direction orthogonal to
the arrangement direction.
13. The internal combustion engine exhaust cooling system according
to claim 12, wherein the arrangement direction of the exhaust ports
in the cylinder head is a horizontal direction, and the direction
orthogonal to the arrangement direction is vertically downward.
14. The internal combustion engine exhaust cooling system according
to claim 8, wherein a plurality of the exhaust ports are provided;
each of the plurality of exhaust ports is arranged and open in a
cylinder head; a plurality of the exhaust passages are formed in an
arrangement inside the exhaust gas cooling adapter, the arrangement
of the plurality of exhaust passages corresponding to an
arrangement of the plurality of exhaust ports; the exhaust ports
are formed curved in a direction orthogonal to an arrangement
direction of the exhaust passages, or the exhaust ports and the
exhaust passages are connected bent in a direction orthogonal to
the arrangement direction; the coolant inlet delivers coolant from
the inside passage toward the outside passage via a middle passage
on one end side in the arrangement direction; and the coolant
outlet discharges coolant from a location where a middle passage on
the other end side in the arrangement direction is connected to the
outside passage, or from near the location.
15. The internal combustion engine exhaust cooling system according
to claim 8, wherein a flow direction guide that guides a flow of
coolant delivered from the coolant inlet to a first middle passage,
of the two middle passages, is provided in the coolant passage, in
a location near the coolant inlet.
16. An internal combustion engine exhaust cooling system
comprising: an exhaust gas cooling adapter that is arranged between
an exhaust port that opens in a cylinder head, and an exhaust
branch pipe, and cools exhaust gas that flows through an exhaust
passage by running coolant through a coolant passage formed inside
of a wall that surrounds the exhaust passage, wherein the exhaust
gas cooling adapter includes a coolant inlet that introduces
coolant into the coolant passage, and a coolant outlet that
discharges coolant outside from the coolant passage; the coolant
passage includes an outside passage of a curve and an inside
passage of a curve that are provided according to a curve in an
exhaust flow produced by a bent shape of a connecting portion
between the exhaust port and the exhaust passage, and two middle
passages that connect the outside passage with the inside passage
at both ends of the two middle passages; a coolant delivery
direction of the coolant inlet is a direction from the inside
passage side of a first middle passage, of the two middle passages,
toward the outside passage side; and the coolant outlet discharges
coolant from a location where a second middle passage, of the two
middle passages, is connected with the outside passage, or from
near the location.
17. The internal combustion engine exhaust cooling system according
to claim 16, wherein the first middle passage is located closer to
the coolant inlet than the second middle passage.
18. The internal combustion engine exhaust cooling system according
to claim 16, wherein a plurality of the exhaust ports are provided;
each of the plurality of exhaust ports is arranged and open in a
cylinder head; a plurality of the exhaust passages are formed in an
arrangement inside the exhaust gas cooling adapter, the arrangement
of the plurality of exhaust passages corresponding to an
arrangement of the plurality of exhaust ports; and the exhaust
ports are formed curved in a direction orthogonal to an arrangement
direction of the exhaust passages, or the exhaust ports and the
exhaust passages are connected bent in a direction orthogonal to
the arrangement direction.
19. The internal combustion engine exhaust cooling system according
to claim 18, wherein the arrangement direction of the exhaust ports
in the cylinder head is a horizontal direction, and the direction
orthogonal to the arrangement direction is vertically downward.
20. The internal combustion engine exhaust cooling system according
to claim 16, wherein a plurality of the exhaust ports are provided;
each of the plurality of exhaust ports is arranged and open in a
cylinder head; a plurality of the exhaust passages are formed in an
arrangement inside the exhaust gas cooling adapter, the arrangement
of the plurality of exhaust passages corresponding to an
arrangement of the plurality of exhaust ports; the exhaust ports
are formed curved in a direction orthogonal to an arrangement
direction of the exhaust passages, or the exhaust ports and the
exhaust passages are connected bent in a direction orthogonal to
the arrangement direction; the coolant inlet delivers coolant from
the inside passage toward the outside passage via a middle passage
on one end side in the arrangement direction; and the coolant
outlet discharges coolant from a location where a middle passage on
the other end side in the arrangement direction is connected to the
outside passage, or from near the location.
21. The internal combustion engine exhaust cooling system according
to claim 16, wherein a flow direction guide that guides a flow of
coolant delivered from the coolant inlet to a first middle passage,
of the two middle passages, is provided in the coolant passage, in
a location near the coolant inlet.
Description
INCORPORATION BY REFERENCE
[0001] This application claims priority to Japanese Patent
Application No. 2010-066974 filed on Mar. 23, 2010, which is
incorporated herein by reference in its entirety including the
specification, drawings and abstract.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to an internal combustion engine
exhaust cooling system in which an exhaust gas cooling adapter that
is arranged between an exhaust port that opens in a cylinder head
and an exhaust branch pipe, and that cools exhaust gas flowing
through an exhaust passage by running coolant through a coolant
passage formed inside of a wall that surrounds the exhaust
passage.
[0004] 2. Description of the Related Art Japanese Patent
Application Publication No. 11-49096 (JP-A-11-49096) and Japanese
Utility Model Application Publication No. 64-15718 (JP-U-64-15718),
for example, describe technologies for cooling exhaust gas in order
to suppress heat damage to the internal combustion engine exhaust
system. In JP-A-11-49096, a connecting member is provided between a
cylinder head and an exhaust branch pipe, and a coolant passage is
provided in this connecting member. This coolant passage is formed
as a concave portion. Coolant introduced from both ends on the
lower side of the coolant passage flows directly into the coolant
passage on the exhaust branch pipe side.
[0005] In JP-U-64-15718, a first exhaust gas cooling adapter is
arranged between a cylinder head and an exhaust branch pipe, and a
second exhaust gas cooling adapter is arranged between the exhaust
branch pipe and a turbocharger. A coolant passage of the first
exhaust gas cooling adapter passes from an inlet provided on a
lower side of one end of an arrangement of exhaust passages
corresponding to exhaust ports, through the lower side of the
arrangement, turns back at the opposite end, and passes through the
upper side of the arrangement, and discharges coolant out from an
outlet directly above the inlet. As a result, the exhaust gas that
has just come out of the exhaust ports is cooled by the exhaust gas
cooling adapter. With the second exhaust gas cooling adapter, a
coolant inlet and a coolant outlet are formed on opposite corners
of a cooling passage formed around a single exhaust passage. This
second exhaust gas cooling adapter runs coolant around the exhaust
passage, thus cooling the exhaust gas that has already been cooled
by the first exhaust gas cooling adapter.
[0006] Exhaust gas discharged from a combustion chamber of an
internal combustion engine via an exhaust port does not flow
uniformly through the exhaust passage. That is, the flow of exhaust
gas may become uneven or the exhaust gas may bump along due to the
shape of the exhaust port, the positional relationship between the
exhaust port and an exhaust gas cooling adapter that is connected
to the exhaust port, or the shape of the exhaust gas cooling
adapter. As a result, a large difference in temperature may occur
at the inner surface of the exhaust gas cooling adapter, which may
cause the exhaust cooling performance to decrease.
[0007] With the connecting member in JP-A-11-49096, the concave
portion that serves as the coolant passage is provided to supply
coolant to the exhaust branch pipe side. Therefore, the shape of
the concave portion itself does not sufficiently surround the
exhaust passage. Moreover, coolant flows directly out to the
exhaust branch pipe side without sufficiently flowing into the
concave portion, so the function of cooling the exhaust gas that
has been discharged from the exhaust port on the cylinder head side
is extremely low. Therefore, this technology does not enable the
exhaust passage of the exhaust gas cooling adapter to be
efficiently cooled.
[0008] With the first exhaust gas cooling adapter in JP-U-64-15718,
exhaust gas discharged from the exhaust port of the internal
combustion engine is cooled by running coolant uniformly along the
entire periphery of the exhaust passage. With such uniform cooling,
in order to sufficiently cool the exhaust gas even at a high
temperature portion that occurs due to the temperature difference
described above, it is necessary to run an overall large amount of
coolant inside the water jacket of the first exhaust gas cooling
adapter. Such an approach, however, increases the size of the
exhaust gas cooling adapter and increases the load on the water-jet
pump. As a result, the internal combustion engine may become
heavier and less fuel efficient.
[0009] With the second exhaust gas cooling adapter in
JP-U-64-15718, cooling is simply performed a second time in order
to protect the turbocharger. Cooling is not aimed at the high
temperature exhaust gas from the exhaust port. Moreover, the
temperature difference described above is not taken into account,
and the flow of coolant is not one that actually addresses the
temperature difference.
SUMMARY OF THE INVENTION
[0010] The invention thus provides an internal combustion engine
exhaust cooling system capable of efficiently cooling an exhaust
passage of an exhaust gas cooling adapter without increasing either
the size of the exhaust gas cooling adapter or the load on a
water-jet pump.
[0011] A first aspect of the invention relates to an internal
combustion engine exhaust cooling system that includes an exhaust
gas cooling adapter that is arranged between an exhaust port that
opens in a cylinder head, and an exhaust branch pipe, and cools
exhaust gas that flows through an exhaust passage by running
coolant through a coolant passage formed inside of a wall that
surrounds the exhaust passage. The exhaust gas cooling adapter
includes a coolant inlet that introduces coolant into the coolant
passage, and a coolant outlet that discharges coolant outside from
the coolant passage. The coolant passage includes a first passage
that is on a high heat receiving side and a second passage that is
on a low heat receiving side, the first passage and the second
passage being provided according to an offset of an amount of heat
received from exhaust gas in a circumferential direction of an
inner surface of the exhaust passage, and two middle passages that
connect the first passage with the second passage at both ends of
the two middle passages. A coolant delivery direction of the
coolant inlet is a direction from the second passage side of a
first middle passage, of the two middle passages, toward the first
passage side. Also, the coolant outlet discharges coolant from a
location where a second middle passage, of the two middle passages,
is connected with the first passage, or from near the location.
[0012] With this internal combustion engine exhaust cooling system,
in the exhaust gas cooling adapter, coolant that is delivered from
the coolant inlet to the coolant passage immediately heads from the
second passage side of the first middle passage, of the two middle
passages, toward the first passage side.
[0013] As a result, the pressure of the coolant delivered from the
coolant inlet is sufficiently transmitted to the first passage,
while little coolant pressure is transmitted to the second passage.
Thus, coolant flows faster in the first passage than it does in the
second passage. As a result, the flow rate of coolant that flows
through the coolant passage is greater in the first passage and
smaller in the second passage, so the temperature at the exhaust
passage portion on the first passage side that tends to increase
can be inhibited from increasing. The exhaust passage portion on
the second passage side essentially tends not to increase in
temperature, so the temperature is able to be inhibited from
increasing even if the coolant flow rate is reduced.
[0014] Therefore, the exhaust passage of the exhaust gas cooling
adapter can be efficiently cooled without increasing the total
coolant flow rate, so the exhaust gas cooling adapter will not
become larger and the load on the water-jet pump will not
increase.
[0015] A second aspect of the invention relates to an internal
combustion engine exhaust cooling system that includes an exhaust
gas cooling adapter that is arranged between an exhaust port that
opens in a cylinder head, and an exhaust branch pipe, and cools
exhaust gas that flows through an exhaust passage by running
coolant through a coolant passage formed inside of a wall that
surrounds the exhaust passage. The exhaust gas cooling adapter
includes a coolant inlet that introduces coolant into the coolant
passage, and a coolant outlet that discharges coolant outside from
the coolant passage. The coolant passage includes an outside
passage of a curve and an inside passage of a curve that are
provided according to a curve in an exhaust flow produced by a
curved shape of the exhaust port, and two middle passages that
connect the outside passage with the inside passage at both ends of
the two middle passages. A coolant delivery direction of the
coolant inlet is a direction from the inside passage side of a
first middle passage, of the two middle passages, toward the
outside passage side. Also, the coolant outlet discharges coolant
from a location where a second middle passage, of the two middle
passages, is connected with the outside passage, or from near the
location.
[0016] In this aspect, in the exhaust gas cooling adapter, coolant
that is delivered from the coolant inlet to the coolant passage
immediately heads from the inside passage side of the first middle
passage, of the two middle passages, toward the outside passage
side.
[0017] As a result, the pressure of the coolant delivered from the
coolant inlet is sufficiently transmitted to the first passage,
while little coolant pressure is transmitted to the inside passage.
Thus, coolant flows faster in the outside passage than it does in
the inside passage, so the flow rate of coolant that flows through
the coolant passage is greater in the outside passage and smaller
in the inside passage.
[0018] The exhaust port is curved, so a curve is produced in the
exhaust flow until the exhaust gas reaches the exhaust gas cooling
adapter. Therefore, in the exhaust gas cooling adapter, the inner
surface of the exhaust passage that corresponds to the outside of
the curve of the exhaust flow tends to increase in temperature due
to the fast exhaust flow and the exhaust gas striking it.
[0019] In this internal combustion engine exhaust cooling system,
as described above, the coolant flow rate is greater in the outside
passage, that is a coolant passage that corresponds to an exhaust
passage inner surface that tends to increase in temperature, than
it is in the inside passage, so an increase in temperature at the
exhaust passage portion that tends to increase in temperature can
be suppressed. The exhaust passage portion that corresponds to the
inside passage essentially tends not to increase in temperature, so
the temperature is able to be inhibited from increasing even if the
coolant flow rate is reduced.
[0020] Therefore, the exhaust passage of the exhaust gas cooling
adapter can be efficiently cooled without increasing the total
coolant flow rate, so the exhaust gas cooling adapter will not
become larger and the load on the water-jet pump will not
increase.
[0021] A third aspect of the invention relates to an internal
combustion engine exhaust cooling system that includes an exhaust
gas cooling adapter that is arranged between an exhaust port that
opens in a cylinder head, and an exhaust branch pipe, and cools
exhaust gas that flows through an exhaust passage by running
coolant through a coolant passage formed inside of a wall that
surrounds the exhaust passage. The exhaust gas cooling adapter
includes a coolant inlet that introduces coolant into the coolant
passage, and a coolant outlet that discharges coolant outside from
the coolant passage. The coolant passage includes an outside
passage of a curve and an inside passage of a curve that are
provided according to a curve in an exhaust flow produced by a bent
shape of a connecting portion between the exhaust port and the
exhaust passage, and two middle passages that connect the outside
passage with the inside passage at both ends of the two middle
passages. A coolant delivery direction of the coolant inlet is a
direction from the inside passage side of a first middle passage,
of the two middle passages, toward the outside passage side. Also,
the coolant outlet discharges coolant from a location where a
second middle passage, of the two middle passages, is connected
with the outside passage, or from near the location.
[0022] In this aspect, in the exhaust gas cooling adapter, coolant
that is delivered from the coolant inlet to the coolant passage
immediately heads from the inside passage side of the first middle
passage, of the two middle passages, toward the outside passage
side.
[0023] As a result, the pressure of the coolant delivered from the
coolant inlet is sufficiently transmitted to the outside passage,
while little coolant pressure is transmitted to the inside passage.
Thus, coolant flows faster in the outside passage than it does in
the inside passage, so the flow rate of coolant that flows through
the coolant passage is greater in the outside passage and smaller
in the inside passage.
[0024] The connecting portion of the exhaust port on the cylinder
head side and the exhaust passage of the exhaust gas cooling
adapter is bent, so a curve is produced in the exhaust flow until
the exhaust gas reaches the exhaust gas cooling adapter. Therefore,
in the exhaust gas cooling adapter, the inner surface of the
exhaust passage that corresponds to the outside of the curve of the
exhaust flow tends to increase in temperature due to the fast
exhaust flow and the exhaust gas striking it.
[0025] In the foregoing aspect, as described above, the coolant
flow rate is greater in the outside passage, that is a coolant
passage that corresponds to an exhaust passage inner surface that
tends to increase in temperature, than it is in the inside passage,
so an increase in temperature at the exhaust passage portion that
tends to increase in temperature can be suppressed. The exhaust
passage portion that corresponds to the inside passage essentially
tends not to increase in temperature, so the temperature is able to
be inhibited from increasing even if the coolant flow rate is
reduced.
[0026] Therefore, the exhaust passage of the exhaust gas cooling
adapter can be efficiently cooled without increasing the total
coolant flow rate, so the exhaust gas cooling adapter will not
become larger and the load on the water-jet pump will not
increase.
[0027] In the aspect described above, the coolant outlet may
discharge coolant in the same direction as a flow direction of
coolant in the first passage.
[0028] Also, the coolant outlet is a passage that discharges
coolant in the same direction as the flow direction of coolant in
the first passage. Therefore, the flow direction of coolant that
has flowed through the first passage at a fast rate does not change
when the coolant flows out to the coolant outlet. As a result, the
flow resistance does not increase when coolant is discharged from
the coolant passage, so the fast coolant flow of the first passage
is not impeded. Therefore, the coolant flows more smoothly, which
further increases the effects of suppressing the exhaust gas
cooling adapter from becoming larger and suppressing the load on
the water-jet pump from increasing.
[0029] In the structure described above, the coolant outlet may
discharge coolant in the same direction as a flow direction of
coolant in the outside passage.
[0030] Also, the coolant outlet is a passage that discharges
coolant in the same direction as the flow direction of coolant in
the outside passage. Therefore, the flow direction of coolant that
has flowed through the outside passage at a fast rate does not
change when the coolant flows out to the coolant outlet. As a
result, the flow resistance does not increase when coolant is
discharged from the coolant passage, so the fast coolant flow of
the outside passage is not impeded. Therefore, the coolant flows
more smoothly, which further increases the effects of suppressing
the exhaust gas cooling adapter from becoming larger and
suppressing the load on the water-jet pump from increasing.
[0031] In the aspect described above, a plurality of the exhaust
ports may be provided, and each of the plurality of exhaust ports
may be arranged and open in a cylinder head. A plurality of the
exhaust passages may be formed in an arrangement inside the exhaust
gas cooling adapter, the arrangement of the plurality of exhaust
passages corresponding to an arrangement of the plurality of
exhaust ports. Further, the exhaust ports may be formed curved in a
direction orthogonal to an arrangement direction of the exhaust
passages, or the exhaust ports and the exhaust passages may be
connected bent in a direction orthogonal to the arrangement
direction.
[0032] In this way, each of the exhaust ports in the cylinder head
and the exhaust passages of the exhaust gas cooling adapter are
arranged (i.e., aligned), and, as described above, the exhaust
ports are formed curved in a direction orthogonal to the
arrangement direction, or the exhaust ports and the exhaust
passages are connected bent in a direction orthogonal to the
arrangement direction. With this kind of structure, the first
passage or the outside passage, and the second passage or the
inside passage, are formed along the arrangement direction, as
described above.
[0033] Therefore, the coolant flow rate is increased on the side
that tends to increase in temperature, and the coolant flow rate is
suppressed on the side that tends not to increase in temperature,
as described above. As a result, the exhaust passage of the exhaust
gas cooling adapter can be efficiently cooled without increasing
the total coolant flow rate, so the exhaust gas cooling adapter
will not become larger and the load on the water-jet pump will not
increase.
[0034] In the aspect described above, a plurality of the exhaust
ports may be provided, and each of the plurality of exhaust ports
may be arranged and open in a cylinder head. A plurality of the
exhaust passages may be formed in an arrangement inside the exhaust
gas cooling adapter, the arrangement of the plurality of exhaust
passages corresponding to an arrangement of the plurality of
exhaust ports. Further, the exhaust ports may be formed curved in a
direction orthogonal to an arrangement direction of the exhaust
passages, or the exhaust ports and the exhaust passages may be
connected bent in a direction orthogonal to the arrangement
direction. Also, the coolant inlet may deliver coolant from the
second passage toward the first passage via a middle passage on one
end side in the arrangement direction, and the coolant outlet may
discharge coolant from a location where a middle passage on the
other end side in the arrangement direction is connected to the
first passage, or from near the location.
[0035] In this way, each of the exhaust ports in the cylinder head
and the exhaust passages of the exhaust gas cooling adapter are
arranged (i.e., aligned), and, as described above, the exhaust
ports are formed curved in a direction orthogonal to the
arrangement direction, or the exhaust ports and the exhaust
passages are connected bent in a direction orthogonal to the
arrangement direction. With this kind of structure, the first
passage and the second passage are formed along the arrangement
direction, as described above.
[0036] Arranging the coolant inlet and the coolant outlet in this
way with respect to the first passage and the second passage makes
it possible to increase the coolant flow rate on the first passage
side that tends to increase in temperature, and suppress the
coolant flow rate on the second passage side that tends not to
increase in temperature, as described above. As a result, the
exhaust passage of the exhaust gas cooling adapter can be
efficiently cooled without increasing the total coolant flow rate,
so the exhaust gas cooling adapter will not become larger and the
load on the water-jet pump will not increase.
[0037] In the structure described above, a plurality of the exhaust
ports may be provided, and each of the plurality of exhaust ports
may be arranged and open in a cylinder head. A plurality of the
exhaust passages may be formed in an arrangement inside the exhaust
gas cooling adapter, the arrangement of the plurality of exhaust
passages corresponding to an arrangement of the plurality of
exhaust ports. Further, the exhaust ports may be formed curved in a
direction orthogonal to an arrangement direction of the exhaust
passages, or the exhaust ports and the exhaust passages may be
connected bent in a direction orthogonal to the arrangement
direction. Also, the coolant inlet may deliver coolant from the
inside passage toward the outside passage via a middle passage on
one end side in the arrangement direction, and the coolant outlet
may discharge coolant from a location where a middle passage on the
other end side in the arrangement direction is connected to the
outside passage, or from near the location.
[0038] In this way, each of the exhaust ports in the cylinder head
and the exhaust passages of the exhaust gas cooling adapter are
arranged (i.e., aligned), and, as described above, the exhaust
ports are formed curved in a direction orthogonal to the
arrangement direction, or the exhaust ports and the exhaust
passages are connected bent in a direction orthogonal to the
arrangement direction. With this kind of structure, the outside
passage and the inside passage are formed along the arrangement
direction, as described above.
[0039] Arranging the coolant inlet and the coolant outlet in this
way with respect to the outside passage and the inside passage
makes it possible to increase the coolant flow rate on the outside
passage side that tends to increase in temperature, and suppress
the coolant flow rate on the inside passage side that tends not to
increase in temperature, as described above. As a result, the
exhaust passage of the exhaust gas cooling adapter can be
efficiently cooled without increasing the total coolant flow rate,
so the exhaust gas cooling adapter will not become larger and the
load on the water-jet pump will not increase.
[0040] In the structure described above, the arrangement direction
of the exhaust ports in the cylinder head may be a horizontal
direction, and the direction orthogonal to the arrangement
direction may be vertically downward.
[0041] When the arrangement direction of the exhaust ports in the
cylinder head and the exhaust passages of the exhaust gas cooling
adapter are set and the direction of the curve of the exhaust flow
is set in this way, the coolant flow rate in the coolant passage
provided on the vertically upper side and extending in the
arrangement direction inside the exhaust gas cooling adapter (i.e.,
the first passage or the outside passage) is increased. Also, the
coolant flow rate in the coolant passage provided on the vertically
lower side and extending in the arrangement direction (i.e., the
second passage or the inside passage) is suppressed. Therefore, the
exhaust passage of the exhaust gas cooling adapter can be
efficiently cooled without increasing the total coolant flow rate,
so the exhaust gas cooling adapter will not become larger and the
load on the water-jet pump will not increase.
[0042] In the aspect described above, a flow direction guide that
guides a flow of coolant delivered from the coolant inlet to a
first middle passage, of the two middle passages, may be provided
in the coolant passage, in a location near the coolant inlet.
[0043] In this way, the flow direction guide that guides the flow
of coolant to an appropriate middle passage may be provided in the
coolant passage. Doing so makes it easy to appropriately split the
flow of the coolant between the first passage and the second
passage or between the outside passage and the inside passage, such
that the flow rate becomes larger in the first passage or the
outside passage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] The features, advantages, and technical and industrial
significance of this invention will be described in the following
detailed description of example embodiments of the invention with
reference to the accompanying drawings, in which like numerals
denote like elements, and wherein:
[0045] FIG. 1 is a longitudinal sectional view of an internal
combustion engine exhaust cooling system according to a first
example embodiment of the invention;
[0046] FIGS. 2A and 2B are perspective views of an exhaust gas
cooling adapter used in the internal combustion engine exhaust
cooling system;
[0047] FIGS. 3A, 3B, and 3C are views of the structure of the
exhaust gas cooling adapter used in the internal combustion engine
exhaust cooling system;
[0048] FIGS. 4A, 4B, and 4C are views of the structure of the
exhaust gas cooling adapter used in the internal combustion engine
exhaust cooling system;
[0049] FIGS. 5A and 5B are views of the spatial configuration of
the water jacket inside the exhaust gas cooling adapter used in the
internal combustion engine exhaust cooling system;
[0050] FIGS. 6A, 6B, and 6C are sectional views of an exhaust gas
cooling adapter used in an internal combustion engine exhaust
cooling system according to a second example embodiment of the
invention; and
[0051] FIGS. 7A and 7B are sectional views of exhaust gas cooling
adapters used in internal combustion engine exhaust cooling systems
according to other example embodiments of the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
First Example Embodiment
[0052] FIG. 1 is a longitudinal sectional view of the structure of
an exhaust cooling system 4 in an exhaust system of an internal
combustion engine 2 according to an example embodiment of the
invention. This internal combustion engine 2 is a V-type 6 cylinder
gasoline engine mounted in a vehicle, and has two banks, one
arranged on the left and one arranged on the right, with a bank
angle of 60.degree.. FIG. 1 shows the exhaust cooling system 4 of
the right bank 6.
[0053] Intake air and fuel are introduced as an air-fuel mixture
into a combustion chamber 6b of a cylinder 6a in the right bank 6
via an intake port 8 and an intake valve 10 from an intake system
during an intake stroke. The air-fuel mixture is compressed by a
piston 6c during a compression stroke, and ignited and combusted by
a spark plug 6d during a combustion stroke. Then gas inside the
combustion chamber 6b is discharged as exhaust gas to the exhaust
system by opening an exhaust valve 12 during an exhaust stroke.
Exhaust gas is also discharged to the exhaust system during the
exhaust stroke from the other two cylinders of the right bank 6 and
the three cylinders of the left bank as well.
[0054] Here, the exhaust system for the right bank 6 side includes
an exhaust port 16 (i.e., a total of three exhaust ports for all of
the cylinders of the right bank 6) formed in a cylinder head 14, an
exhaust gas cooling adapter 18 that is connected to the cylinder
head 14 at the opening of the exhaust port 16, and an exhaust
branch pipe 20 that is connected to the exhaust gas cooling adapter
18. Other than these, an exhaust gas control catalyst and the like
are provided downstream in the exhaust system of the right bank 6.
The exhaust system of the left bank similarly includes a total of
three exhaust ports formed in the cylinder head, an exhaust gas
cooling adapter, and an exhaust branch pipe. In this example
embodiment, the exhaust gas cooling adapter of the left bank has
the same structure as the exhaust gas cooling adapter 18 of the
right bank 6. However, the positional relationship of the axis with
the exhaust port side, the angle at which it is mounted to the
cylinder head, or the length or curved shape or the like may be
different.
[0055] FIGS. 2 to 4 are views of the structure of the exhaust gas
cooling adapter 18 of the exhaust system of the right bank 6. FIG.
2A is a perspective view from an exhaust inlet 22 side, and FIG. 2B
is a perspective view from an exhaust outlet 24 side. FIG. 3A is a
plan view, FIG. 3B is a front view, and FIG. 3C is a bottom view.
FIG. 4A is a left side view, FIG. 4B is a right side view, and FIG.
4C is a rear view. Incidentally, in FIGS. 2A and 2B, the spatial
configuration of a water jacket 34 on the inside is indicated by
the broken line.
[0056] The exhaust gas cooling adapter 18 is arranged between the
exhaust port 16 that opens in the cylinder head 14 of the right
bank 6 and the exhaust branch pipe 20, as shown in FIG. 1. The
exhaust gas cooling adapter 18 cools exhaust gas discharged from
the exhaust port 16 and discharges the cooled exhaust gas to the
exhaust branch pipe 20 side, thereby inhibiting heat damage to the
exhaust system of the right bank 6.
[0057] This kind of exhaust gas cooling adapter 18 is molded out of
metal material such as aluminum alloy or iron alloy, for example,
and has a cylinder head side connecting surface 28 with an open
exhaust inlet 22 formed on the exhaust upstream side. Three of
these exhaust inlets 22 are provided arranged in a straight line,
corresponding to the position and number of the exhaust ports 16 of
the cylinder head 14 of the right bank 6.
[0058] On the exhaust downstream side, an exhaust branch pipe side
connecting surface 30 with an open exhaust outlet 24 is formed.
Three of these exhaust outlets 24 are provided arranged in a
straight line, corresponding to the exhaust inlets 22. Each exhaust
inlet 22 is connected to a corresponding exhaust outlet 24 by a
corresponding exhaust passage 32 formed inside the exhaust gas
cooling adapter 18.
[0059] Bolt fastening portions 28a for fastening the exhaust gas
cooling adapter 18 itself to an adapter connecting surface 14a on
the cylinder head 14 side with bolts are formed on the exhaust gas
cooling adapter 18 at peripheral portions of the cylinder head side
connecting surface 28. The exhaust gas cooling adapter 18 is fixed
to the cylinder head 14 by inserting bolts into bolt insertion
holes 28b formed in the bolt fastening portions 28a and screwing
them into threaded holes in the adapter connecting surface 14a on
the cylinder head 14 side. As a result, the exhaust port 16 on the
cylinder head 14 side can be connected with the exhaust passage 32
on the exhaust gas cooling adapter 18 side.
[0060] Moreover, bolt fastening portions 30a for fastening the
exhaust branch pipe 20 with bolts are formed on the exhaust gas
cooling adapter 18 at peripheral portions of the exhaust branch
pipe side connecting surface 30. Threaded holes 30b are formed in
these bolt fastening portions 30a. The exhaust branch pipe 20 is
connected by screwing in bolts through insertion holes formed in
flanges 20a on the exhaust branch pipe 20 side. As a result, the
exhaust passage 32 on the exhaust gas cooling adapter 18 side can
be connected with the exhaust passage 20b on the exhaust branch
pipe 20 side.
[0061] In this way, a water jacket 34 is formed around the exhaust
passage 32, inside the wall of the exhaust gas cooling adapter 18
that is mounted to the internal combustion engine 2. FIGS. 5A and
5B are views of the spatial configuration of the water jacket 34
inside the exhaust gas cooling adapter 18. FIGS. 5A and 5A is a
perspective view from the exhaust inlet 22 side, and FIGS. 5A and
5B is a perspective view from the exhaust outlet 24 side.
[0062] As shown in FIGS. 2 to 4, a coolant introducing portion 36
is provided on the vertically lower side of the water jacket 34 on
the exhaust gas cooling adapter 18, and a coolant discharging
portion 38 is provided on the vertically upper side of the water
jacket 34 in the exhaust gas cooling adapter 18.
[0063] Coolant is introduced into the water jacket 34 from a
coolant inlet 36a formed in the coolant introducing portion 36, and
after flowing through the water jacket 34, is discharged to an
external coolant circulation path via a coolant outlet 38a formed
in the coolant discharging portion 38, as shown by the arrows in
FIGS. 5A and 5B.
[0064] As a result, the amount of heat transmitted from high
temperature exhaust gas via inner peripheral surfaces 32a and 32b
(FIG. 1) of the exhaust passage 32 is absorbed by the coolant
flowing through coolant passages 34a, 34b, 34c, 34d, and 34e of the
water jacket 34, thereby cooling the exhaust gas. The cooled
exhaust gas is then discharged to the exhaust branch pipe 20
side.
[0065] Here, as shown by the alternate long and short dash lines in
FIG. 1, the axis X1 of the exhaust port 16 is at an angle .theta.
to the axis X2 of the exhaust passage 32. Instead of the axes X1
and X2 crossing each other, they may also be non-crossing and
non-parallel by an angle .theta..
[0066] In this example embodiment, the axis X2 of the exhaust
passage 32 is bent vertically downward at an angle .theta. with
respect to the axis X1 of the exhaust port 16. Therefore, the inner
peripheral surface 32a on the vertically upper side of the exhaust
passage 32 forms an area that slopes toward the exhaust port 16.
The inner peripheral surface 32b on the vertically lower side is
not an area that slopes toward the exhaust port 16, but instead
slopes in the opposite direction, i.e., away from the exhaust port
16.
[0067] In this way, the inner peripheral surface 32a on the
vertically upper side of the exhaust passage 32 has a shape that
slopes toward the exhaust port 16. Therefore, exhaust gas that has
been introduced from the exhaust port 16 into the exhaust passage
32 of the exhaust gas cooling adapter 18 strikes the inner
peripheral surface 32a on the vertically upper side comparatively
harder than it strikes the inner peripheral surface 32b on the
vertically lower side.
[0068] Moreover, the exhaust port 16 extends in a curved shape from
the combustion chamber 6b to the exhaust gas cooling adapter 18,
and the vertically upper side is on the outside of the curve.
Therefore, high temperature exhaust flows faster at the inner
peripheral surface 32a on the vertically upper side than it does at
the inner peripheral surface 32b on the vertically lower side, so
high temperature exhaust gas strikes the inner peripheral surface
32a on the vertically upper side hard. Thus, the inner peripheral
surface 32a on the vertically upper side receives a particularly
large amount of heat. That is, the inner peripheral surface 32a on
the vertically upper side is a high heat receiving side and the
inner peripheral surface 32b on the vertically lower side is a low
heat receiving side.
[0069] In this kind of flow state, high temperature exhaust gas
transfers heat to the inner peripheral surfaces 32a and 32b, such
that the exhaust gas itself is cooled, after which it flows out to
the exhaust passage 20b on the exhaust branch pipe 20 side. Here,
in the water jacket 34, the position where coolant is introduced at
the coolant inlet 36a is a position, near the coolant passage 34b,
of the coolant passage 34d that communicates the coolant passage
34b on the vertically lower side with the coolant passage 34a on
the vertically upper side on one end side of the exhaust passages
32 in the direction in which the exhaust passages 32 are arranged
(also simply referred to as the "arrangement direction"). The
coolant inlet 36a delivers coolant toward the coolant passage 34a
on the vertically upper side from a position on the coolant passage
34b side that is on the vertically lower side.
[0070] That is, the direction in which coolant is delivered from
the coolant inlet 36a is the direction from the coolant passage 34b
side of the coolant passage 34d, that is one of the middle
passages, toward the coolant passage 34a side. The coolant passage
34b is on the vertically lower side and is a passage on the inside
of the curve of the exhaust flow that follows the curve of the
exhaust port 16 (the coolant passage 34b may also be referred to as
an "inside passage" in this specification). The coolant passage
34a, on the other hand, is on the vertically upper side and is a
passage on the outside of the curve of the exhaust flow (the
coolant passage 34a may also be referred to as an "outside passage"
in this specification).
[0071] Also, the direction in which coolant is delivered from the
coolant inlet 36a is the direction from the coolant passage 34b
side of the coolant passage 34d, that is one of the middle
passages, toward the coolant passage 34a side. The coolant passage
34b is on the vertically lower side and is a passage on the inside
of the curve of the exhaust flow that follows the bend at the
connection of the exhaust port 16 and the exhaust passage 32 (the
coolant passage 34b may also be referred to as an "inside passage"
in this specification). The coolant passage 34a, on the other hand,
is on the vertically upper side and is a passage on the outside of
the curve of the exhaust flow (the coolant passage 34a may also be
referred to as an "outside passage" in this specification).
[0072] Therefore, coolant flows faster through the coolant passage
34a that is the outside passage than it does through the coolant
passage 34b that is the inside passage. The following effects are
able to be obtained with the first example embodiment described
above.
[0073] As described above, the exhaust port 16 is curved in a
direction orthogonal to the arrangement direction thereof.
Moreover, the connecting portion of the exhaust port 16 and the
exhaust passage 32 of the exhaust gas cooling adapter 18 that is
connected to the exhaust port 16 is bent in a direction orthogonal
to the arrangement direction. The curve and the bend are both
vertically downward. In accordance with this, the exhaust flow is
in a direction that is orthogonal to the arrangement direction, and
curves vertically downward.
[0074] As a result of this curve in the exhaust flow, the coolant
passage 34a that is formed in the arrangement direction in the
exhaust gas cooling adapter 18 and arranged on the vertically upper
side functions as a first passage and an outside passage that
corresponds to the inner peripheral surface 32a on the high heat
receiving side of the exhaust passage 32. The coolant passage 34b
that is formed in the arrangement direction and arranged on the
vertically lower side functions as a second passage and an inside
passage that corresponds to the inner peripheral surface 32b on the
low heat receiving side of the exhaust passage 32. Also, the two
coolant passages 34d and 34e that connect these coolant passages
34a and 34b together at the both ends function as middle
passages.
[0075] In this exhaust gas cooling adapter 18, the flow direction
of coolant delivered from the coolant inlet 36a into the water
jacket 34 is toward the coolant passage 34a side. Therefore, as
shown by the arrows in FIGS. 5A and 5B, the main stream of the
coolant flows through the coolant passage 34d that is the first
middle passage of the two middle passages (i.e., coolant passages
34d and 34e) from the coolant passage 34b side toward the coolant
passage 34a side. Accordingly, the amount (i.e., the flow rate) of
coolant that flows toward the coolant passage 34b is small.
Incidentally, in this example embodiment, the coolant passage 34d
is located closer to the coolant inlet 36 than the coolant passage
34e is.
[0076] As a result, the pressure of the coolant delivered from the
coolant inlet 36a is sufficiently transmitted to the coolant
passage 34a, while little coolant pressure is transmitted to the
coolant passage 34b. Thus, coolant flows faster in the coolant
passage 34a than it does in the coolant passage 34b. As a result,
the flow rate of coolant that flows through the water jacket 34 is
greater in the coolant passage 34a and smaller in the coolant
passage 34b, so the temperature at the inner peripheral surface 32a
on the vertically upper side of the exhaust passage 32 that tends
to increase can be inhibited from increasing. Therefore, resistance
to boiling at the coolant passage 34a as a result of heat transfer
from the inner peripheral surface 32a can also be improved.
[0077] The inner peripheral surface 32b on the vertically lower
side essentially tends not to increase in temperature, so the
temperature is able to be inhibited from increasing even if the
coolant flow rate in the corresponding coolant passage 34b is
reduced. In this way, the exhaust passage 32 of the exhaust gas
cooling adapter 18 can be efficiently cooled without increasing the
total flow rate of coolant that flows through the water jacket 34,
so the exhaust gas cooling adapter 18 will not become larger and
the load on the water-jet pump will not increase.
[0078] Also, the coolant outlet 38a is a passage that discharges
coolant in the same direction as the direction in which coolant
flows (i.e., the flow direction of coolant) in the coolant passage
34a. Therefore, as shown by the arrows in FIGS. 5A and 5B, the flow
direction of coolant that has flowed through the coolant passage
34a at a fast rate does not change when the coolant flows out to
the coolant outlet 38a. As a result, the flow resistance does not
increase when the coolant flows out of the coolant passage 34a, so
the fast coolant flow of the coolant passage 34a is not
impeded.
[0079] Therefore, the coolant flows more smoothly, which further
increases the effects of suppressing the exhaust gas cooling
adapter 18 from becoming larger and suppressing the load on the
water-jet pump from increasing.
Second Example Embodiment
[0080] FIG. 6 is a sectional view of exhaust gas cooling adapters
118, 218, and 318 used in an exhaust cooling system according to a
second example embodiment of the invention. Incidentally, the other
structure of the exhaust cooling system is the same as it is in the
first example embodiment described above.
[0081] With the exhaust gas cooling adapter 118 shown in FIG. 6A, a
coolant inlet 136a of a coolant introducing portion 136 that
introduces coolant into a water jacket 134 opens into a coolant
passage 134b (that functions as a second passage and an inside
passage) that is arranged on the vertically lower side and extends
in the direction in which exhaust passages 132 are arranged (i.e.,
in the arrangement direction of the exhaust passages 132), and
delivers coolant into this coolant passage 134b.
[0082] A flow direction guide 136b is formed on a side of an edge
portion of a portion of the coolant inlet 136a that opens to the
coolant passage 134b side, that is opposite a coolant passage 134d
(that functions as a middle passage) side. A tip end of this flow
direction guide 136b points toward the coolant passage 134d side.
Therefore, the pressure of the coolant that has been introduced
from the coolant inlet 136a into the coolant passage 134b is
directed toward the coolant passage 134d side by the flow direction
guide 136b.
[0083] As a result, as shown by the arrows in the drawing, the main
stream of the coolant flows toward the coolant passage 134d side,
and the flow rate of this coolant is large. The flow rate of the
coolant that flows through the coolant passage 134b toward the side
with a coolant passage 134e that is a middle passage on the
opposite side is small.
[0084] The flow of the coolant (i.e., the coolant pressure) in the
coolant passage 134d turns directly into the flow in a coolant
passage 134a (that functions as a first passage and an outside
passage) that is arranged on the vertically upper side and extends
in the direction in which the exhaust passages 132 are arranged
(i.e., the arrangement direction of the exhaust passages 132), and
then flows to a coolant discharging portion 138.
[0085] The direction of a coolant outlet 138a of the coolant
discharging portion 138 is the same as the direction of the coolant
passage 134a, so the coolant also flows inside the coolant outlet
138a without losing any pressure, and is discharged outside as it
is from the coolant outlet 138a.
[0086] With the exhaust gas cooling adapter 218 shown in FIG. 6B, a
coolant inlet 236a of a coolant introducing portion 236 that
introduces coolant into a water jacket 234 opens into a coolant
passage 234b (that functions as a second passage and an inside
passage) that is arranged on the vertically lower side and extends
in the direction in which exhaust passages 232 are arranged (i.e.,
in the arrangement direction of the exhaust passages 232), and
delivers the coolant into this coolant passage 234b, similar to
FIG. 6A.
[0087] However, in the example shown in FIG. 6B, a flow direction
guide 236b is formed on a wall portion side of an opposing exhaust
passage 232, instead of on an edge portion of the coolant inlet
236a. A tip end of this flow direction guide 236b is formed pointed
toward an edge portion of the coolant inlet 236a, that is on the
side opposite a coolant passage 234d (that functions as a middle
passage) side.
[0088] Accordingly, the pressure of the coolant that has been
introduced from the coolant inlet 236a into the coolant passage
234b is directed toward the coolant passage 234d side by the sloped
surface of the flow direction guide 236b. As a result, as shown by
the arrows in the drawing, the main stream of the coolant flows
toward the coolant passage 234d side, and the flow rate of this
coolant is large. The flow rate of the coolant that flows through
the coolant passage 234b toward the side with a coolant passage
234e that is a middle passage on the opposite side is small.
[0089] The flow of the coolant (i.e., the coolant pressure) in this
coolant passage 234d turns directly into the flow in a coolant
passage 234a (that functions as a first passage and an outside
passage) that is arranged on the vertically upper side and extends
in the direction in which the exhaust passages 232 are arranged
(i.e., the arrangement direction of the exhaust passages 232), and
then flows to a coolant discharging portion 238.
[0090] The direction of a coolant outlet 238a of the coolant
discharging portion 238 is the same as the direction of the coolant
passage 234a, so the coolant flows without losing any pressure, and
is discharged outside as it is from the coolant outlet 238a.
[0091] With the exhaust gas cooling adapter 318 shown in FIG. 6C, a
coolant inlet 336a of a coolant introducing portion 336 that
introduces coolant into a water jacket 334 opens into a coolant
passage 334b (that functions as a second passage and an inside
passage) that is arranged on the vertically lower side and extends
in the direction in which exhaust passages 332 are arranged (i.e.,
in the arrangement direction of the exhaust passages 332), and
delivers the coolant into this coolant passage 334b. This is the
same as in FIG. 6A.
[0092] However, compared with FIG. 6A, the coolant inlet 336a of
the coolant introducing portion 336 is farther away from a coolant
passage 334d (that functions as a middle passage) and is provided
in a position facing a coolant passage 334c that connects a coolant
passage 334a (that functions as a first passage and an outside
passage) with the coolant passage 334b at a center portion.
Therefore, a flow direction guide 336b that is formed on an opening
edge portion of a coolant inlet 336a on the side opposite the
coolant passage 334d (that functions as a middle passage) is formed
longer and extending toward the coolant passage 334d side, such
that sufficient coolant pressure reliably reaches the coolant
passage 334d.
[0093] As a result, as shown by the arrows in the drawing, the main
stream of the coolant flows toward the coolant passage 334d side,
and the flow rate of this coolant is large. The flow rate of the
coolant that flows through the coolant passage 334b toward the side
with a coolant passage 334e that is a middle passage on the
opposite side is small.
[0094] The flow of the coolant (i.e., the coolant pressure) in the
coolant passage 334d turns directly into the flow in a coolant
passage 334a that is arranged on the vertically upper side and
extends in the direction in which the exhaust passages 332 are
arranged (i.e., in the arrangement direction of the exhaust
passages 332), and then flows to a coolant discharging portion
338.
[0095] The direction of a coolant outlet 338a of the coolant
discharging portion 338 is the same as the direction of the coolant
passage 334a, so the coolant flows without losing any pressure, and
is discharged outside as it is from the coolant outlet 338a.
[0096] The following effects are able to be obtained with the
second example embodiment described above. The main flow of coolant
is able to be directed toward the coolant passage 134a, 234a, or
334a via the coolant passage 134d, 234d, or 334d by the flow
direction guide 136b, 236b, or 336b also when the coolant
introducing portion 136, 236, or 336 is mounted on the coolant
passage 134b, 234b, or 334b side in this way.
[0097] As a result, effects similar to those described in the first
example embodiment are able to be obtained.
Other Example Embodiments
[0098] With an exhaust gas cooling adapter 418 shown in FIG. 7A,
when a coolant inlet 436a of a coolant introducing portion 436 is
connected to a coolant passage 434b that functions as a second
passage and an inside passage, the coolant inlet 436a may be formed
at an angle such that the main stream of coolant is directed toward
a coolant passage 434d that is a middle passage, instead of using a
flow direction guide.
[0099] As a result, as shown by the arrows in the drawing, the flow
of the coolant (i.e., the coolant pressure) in the coolant passage
434d turns directly into the flow in a coolant passage 434a that
functions as a first passage and an outside passage, and then flows
to a coolant discharging portion 438. The coolant then flows
without losing any pressure, and is discharged outside as it is
from a coolant outlet 438a. This structure also enables effects
similar to those obtained in the first example embodiment to be
obtained.
[0100] In the foregoing example embodiments, the direction of the
coolant outlet of the coolant discharging portion follows the flow
direction of coolant in the coolant passage that functions as the
first passage and the outside passage. Alternatively, however, the
direction of a coolant outlet 538a of a coolant discharging portion
538 may be a direction that is different from the flow direction of
coolant in a coolant passage 534a that functions as a first passage
and an outside passage, as shown in FIG. 7B. In the example shown
in FIG. 7B, the direction of the coolant outlet 538a is a direction
that is orthogonal to the flow direction of coolant in the coolant
passage 534a. With this structure as well, the pressure of coolant
delivered from a coolant inlet 536a of a coolant introducing
portion 536 is transmitted to the coolant passage 534a via a
coolant passage 534d that serves as a middle passage, so a
sufficiently large coolant flow rate is able to be ensured in the
coolant passage 534a. As a result, effects similar to those
obtained in the first example embodiment are able to be
obtained.
[0101] Even if the exhaust port and the exhaust passage of the
exhaust cooling adaptor are not bent, and there is only the curve
of the exhaust port, the inner peripheral surface of the exhaust
passage of the exhaust gas cooling adapter that is on the outside
of the curve will become the high temperature receiving side, and
the coolant passage that corresponds to this inner peripheral
surface will become the first passage. Therefore, the effects
described above can be obtained by having coolant flow in the
manner described in the example embodiments described above.
[0102] Incidentally, even if only the connecting portion of the
exhaust port and the exhaust passage of the exhaust gas cooling
adapter is bent, the inner peripheral surface of the exhaust
passage of the exhaust gas cooling adapter that is on the outside
of the bend will become the high temperature receiving side, and
the coolant passage that corresponds to this inner peripheral
surface will become the first passage. Therefore, the effects
described above can be obtained by having coolant flow in the
manner described in the example embodiments described above.
[0103] FIG. 1 is a view of an example in which the invention is
applied to a V-type 6 cylinder internal combustion engine. However,
the invention may also be applied to an engine having in-line
configuration, as well as to an engine with a number of cylinders
other than six, such as four cylinders or eight cylinders or the
like.
* * * * *