Note: Descriptions are shown in the official language in which they were submitted.
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HEAT EXCHANGER AND HEAT EXCHANGE DEVICE
FILED OF THE INVENTION
The present invention relates to a heat exchanger and a heat exchange
device employing the heat exchanger.
BACKGROUND OF THE INVENTION
Generally, a heat exchanger is designed to effect heat exchange between a
first heating medium that flows along an inner periphery of a heat exchange
tube
and a second heating medium that flows along an outer periphery of the heat
exchange tube. It is known to employ a heat exchanger in a heat exchange
device (see JP 2012-184681 A, for example).
Referring to FIG. 13 hereof, explanation will be made as to the heat
exchange device disclosed in JP 2012-184681. As shown in FIG. 13, an exhaust
heat recovery apparatus 200, known also as a heat exchange device, includes a
heat recovery passage 202 in which a heat exchanger 201 is housed for
effecting
heat exchange, and a bypass 203 branched off from the heat recovery passage
202 and where heat exchange is not performed.
The heat exchanger 201 is comprised of a core case 211, a pair of end
plates 212, 213 for closing respective ends of the core case 211, and a
plurality of
heat exchange tubes 215 disposed between the two end plates 212, 213 and
allowing an exhaust gas to flow inside thereof. Heat exchange is effected
between the exhaust gas that flows through the heat exchange tubes and a
medium that flows externally.
The exhaust heat recovery apparatus 200 employing the heat exchanger
210 is generally mounted to an underside of a floor of a vehicle body. Since a
mounting space on the underside of the vehicle body floor is small, it is
desired
that the exhaust heat recovery apparatus 200 be compact and small. If the heat
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exchanger 210 is downsized, the exhaust heat recovery apparatus per se becomes
compact and small.
In addition, in a case in which the heat exchanger 210 is employed in an
apparatus other than the exhaust heat recovery apparatus 200, if the heat
exchanger 210 is downsized, this brings the advantage that the apparatus in
which the heat exchanger 210 is employed can be positioned with increased
freedom. There is therefore a demand for downsizing of a heat exchanger.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a
heat exchanger comprising: a tubular core case; a pair of end plates for
closing
opposite ends of the core case; and a plurality of heat exchange tubes
supported
at opposite ends by the end plates and allowing a first heating medium to flow
inside thereof, so as to effectuate heat exchange between the first heating
medium and a second heating medium flowing along an outer periphery of the
heat exchange tubes, wherein one of the end plates is disposed on an upstream
side of flow of the first heating medium as an upstream end plate while
another
one of the end plates is disposed on a downstream side of the flow of the
first
heating medium as a downstream end plate, the downstream end plate
comprises a downstream bottom surface part for supporting downstream end
parts of the heat exchange tubes, and a downstream wall part formed integrally
with and rising from a peripheral edge of the downstream bottom surface part,
and a top end part of the downstream wall part is oriented toward upstream of
the flow of the first heating medium.
In the above-described inventive arrangement, the downstream end plate
is comprised of the downstream bottom surface part for supporting the heat
exchange tubes, and the downstream wall part formed integrally with and rising
from the peripheral edge of the downstream bottom surface part, and the top
end
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part of the downstream wall part is disposed in orientation toward an upstream
side. Since the top end part of the downstream wall part is oriented toward
upstream, the top end part of the downstream wall part is positioned further
upstream than the downstream end parts of the heat exchange tubes, whereby
the heat exchanger is downsized.
Preferably, the downstream wall part is joined with the core case only at
a top end side thereof.
It is preferred that the upstream end plate comprise an upstream bottom
surface part for supporting upstream end parts of the heat exchange tubes, and
an upstream wall part formed integrally with and rising from a peripheral edge
of the upstream bottom surface part, and the top end part be oriented toward
downstream of the flow of the first heating medium.
Desirably, the upstream wall part is joined with the core case only at a
top end side thereof.
It is preferred that the core case have a second heating medium inlet for
introducing the second heating medium into the core case, and a guide part be
provided in the vicinity of the second heating medium inlet for guiding the
second heating medium toward the upstream side of the heat exchange tubes.
In a preferred form, the guide part comprises a sheet-shaped guide plate
joined with an inner peripheral surface part of the core case and forming a
closed
cross section between the guide plate and the inner peripheral surface part of
the
core case, while the guide plate has a guide aperture formed at an upstream-
side
end part thereof, through which aperture the second heating medium is guided
toward the upstream side of the heat exchange tubes.
It is preferred that the guide part comprise a sheet-shaped guide plate
joined with an outer peripheral surface part of the core case and defining a
closed
cross section between the guide plate and the outer peripheral surface part of
the
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core case, and the core case have a guide aperture formed at an upstream end
part thereof, through which aperture the second heating medium is guided
toward the upstream side of the heat exchange tubes.
Desirably, the guide aperture is formed at a position corresponding to an
inter-layer space of the heat exchange tubes.
In a desired form, the core case has a recessed part recessed inwardly
along a direction of flow of the first heating medium.
According to a second aspect of the present invention, there is provided a
heat exchange device which comprises: a branching part for allowing passage of
an exhaust gas therethrough and branching the exhaust gas into two streams; a
first flow passage extending from the branching part; a second flow passage
extending from the branching part along the first flow passage; a heat
exchanger
disposed on the second flow passage for recovering energy from heat of the
exhaust gas; and a valve disposed openably/closably on one of the first flow
passage and the second flow passage for changing a direction of flow of the
exhaust gas, wherein the heat exchanger comprises a heat exchanger according
to the first aspect of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Certain preferred embodiments of the present invention will be described
in detail below, by way of example only, with reference to the accompanying
drawings, in which:
FIG. 1 is a top plan view illustrating an exhaust heat recovery apparatus
employing a heat exchanger according to a first embodiment of the present
invention:
FIG. 2 is a cross-sectional view taken along line 2 ¨ 2 of FIG. 1;
FIG. 3 is a perspective view illustrating the heat exchanger of FIG. 2;
FIG. 4 is an exploded perspective view illustrating a lower case half and a
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guide plate;
FIG. 5 is a perspective view illustrating the lower case half and the guide
plate joined together;
FIG. 6 is a schematic view illustrating an operation of the heat exchanger
of FIG. 2;
FIG. 7 is a cross-sectional view illustrating a heat exchanger according to
a second embodiment of the present invention;
FIG. 8 is a perspective view illustrating the heat exchanger of FIG. 7;
FIG. 9 is a cross-sectional view taken along line 9 ¨ 9 of FIG. 7;
FIG. 10 is an exploded perspective view illustrating a lower case half and
a guide plate according to the second embodiment of the present invention;
FIG. 11 is a perspective view illustrating the lower case half and the
guide plate, joined together, of FIG. 10;
FIG. 12 is a cross-sectional view illustrating a heat exchanger according
to a third embodiment of the present invention; and
FIG. 13 is a cross-sectional view illustrating a conventional, basic
arrangement.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(Embodiment 1)
Reference is made initially to FIG. 1. As shown in FIG. 1, an exhaust
heat recovery apparatus 10 (heat exchange device) includes an exhaust gas
inlet
11 for introducing exhaust gas (first heating medium) generated in an internal
combustion engine (not shown), a branching part 12 connected to the inlet 11,
a
first flow passage 13 connected to the branching part 12 and extending
downstream of the inlet 11, a second flow passage 14 extending from the
branching part 12 along the first flow passage 13, a heat exchanger 30 forming
part of the second flow passage 14 for transmitting heat of the exhaust gas to
a
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medium (second heating medium), a thermoactuator 16 connected to the heat
exchanger 30, a valve chamber 17 to which the first and second flow passages
13,
14 are connected at downstream ends thereof, a discharge outlet 18 connected
to
the valve chamber 17 for discharging the exhaust gas, and a valve housed in
the
valve chamber 17 and adapted to close the first flow passage 13 or the second
flow passages 14. The valve chamber 17 serves also as a merging part where
streams of the exhaust gas passed through the first and second flow passages
merge or meet.
In the state shown in the Figure, the valve 19 closes the first flow passage
13. At this time, the second flow passage 14 is opened to allow the exhaust
gas
to pass therethrough. On the other hand, when the valve 19 swings on a certain
condition, the valve 19 closes the second flow passage 14, whereupon the first
flow passage 13 is opened to allow passage of the exhaust gas therethrough.
A medium introducing pipe 21 (second heating medium introducing pipe)
is connected to a side of the heat exchanger 30 for introducing heating
medium.
An actuator support member 22 is connected to the heat exchanger 30 for
supporting the thermoactuator 16. A medium discharge pipe 23 (second heating
medium discharge pipe) is connected to the actuator support member 22 for
discharging the heating medium.
Namely, the medium is introduced into the heat exchanger 30 through
the medium introducing pipe 21. The thus-introduced medium receives heat
from the exhausted gas within the heat exchanger 30 and discharged through
the medium discharge pipe 23. That is, the heat exchanger 30 recovers energy
of the exhaust gas. Detailed discussion as to the heat exchanger 30 will be
made with reference to Figures that follow.
As shown in FIG. 2, the heat exchanger 30 is comprised of a generally
square-tube-shaped core case 31 adapted to allow flow of the medium
internally,
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upstream and downstream end plates 32, 33 mounted so as to close openings at
opposite ends of the core case 31, a heat exchange tube 34 mounted between the
upstream and downstream end plates 32, 33 and adapted to allow passage of the
exhaust gas internally, and a fin 35 housed in the heat exchange tube 34.
Turning now to FIG. 3, the upstream end plate 32 includes a plurality of
heat exchange tubes 34 inserted thereinto. The downstream end plate 33 is
similarly configured.
The core case 31 is comprised of a lower case half 41 having a generally
U-shape as viewed in front elevation and forming a lower half of the core case
31,
and an upper case half joined with the lower case half 41 to form an upper
part of
the core case 31. The upper case half 42 is also generally U shaped as view in
front elevation.
The lower case half 41 has a side surface portion 41a which is provided
with a medium inlet 41b (second heating medium inlet) for introducing medium.
The medium introducing pipe 21 (FIG. 1) is connected to the medium inlet 41b.
The upper case half 42 is comprised of a connecting part 42a connected to
the upstream end plate 32, the downstream end plate 33 and the lower case half
41, and a recessed part 42b recessed inwardly from the connecting part 42a. On
an upper surface part 42c of the recessed part 42b, a medium discharge outlet
42d (second heating medium discharge outlet) is provided for discharging the
medium. The actuator support member 22 is connected to the medium
discharge outlet 42d.
Turning back to FIG. 2, the upstream end plate 32 includes a generally
rectangular-shaped upstream bottom surface part 32a for supporting an
upstream end part 34a of the heat exchange tube 34, and an upstream wall part
32b formed integrally with and rising from a peripheral edge of the upstream
bottom surface part 32a. The upstream wall part 32b extends toward
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downstream from the upstream bottom surface part 32a. Top end part 32c of
the upstream wall part 32b is located at a downstream-most position.
The upstream bottom surface part 32a has a plurality of support holes
32d for allowing passage of and supporting the heat exchange tube 34. Of the
upstream wall part 32b, only the top end 32c is joined with the core case 31.
The downstream end plate 33 is configured similarly. Namely, the
downstream end plate 33 is comprised of a downstream bottom surface part 33a
having a generally rectangular shape and supporting a downstream end part 34b
of the heat exchange tube 34, and a downstream wall part 33b formed integrally
with and rising from a peripheral edge of the downstream bottom surface part
33a. The downstream wall part 33b extends from the downstream bottom
surface part 33a toward upstream. Top end part 33c of the downstream wall
part 33b is located at an upstream-most position.
The downstream bottom surface part 33a has a plurality of support holes
33d for allowing passage of and supporting the heat exchange tube 34. Of the
downstream wall part 33b, only the top end part 33c is connected to the core
case
31.
The core case 31 has a recessed part 42b recessed inwardly along the
direction of flow of the exhaust gas. Provision of the recessed part 42b
imparts
increased rigidity to the core case 31. This makes it possible to increase
rigidity
against the direction of expansion of the medium and hence to impart a
prolonged life to the heat exchanger 10.
Of the upstream wall part 32b, only the top end part 32c is connected to
the core case 31. Thus, the peripheral edge of the upstream wall part 32b is
not
joined with the core case 31. As a result, a member for introducing exhaust
gas
can be connected directly to the peripheral edge of the upstream wall part
32b.
Since direct connection of the heat exchanger 10 with the associated flow
passage
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becomes possible, an additional part for connecting the heat exchange with the
associated flow passage will not be required. This leads to the advantage that
the number of required parts may be decreased. The same can be said of the
downstream end plate 33.
At a lower part of the core case 31, there is provided a guide part 37 for
guiding the medium toward upstream of the heat exchange tube 34. The guide
part 37 is comprised of a guide plate 50 which is connected to an inner
peripheral
surface part 31a of the core case 31 in such a manner as to form a closed
cross
section between the guide plate 50 and the inner peripheral surface part 31a.
The upstream wall part 32b of the upstream end plate 32 and the
downstream wall part 33b of the downstream end plate 33 desirably have a
length in the range of 10 mm to 24 mm. The upstream and downstream wall
parts 32b, 33b are overlapped with respective upstream and downstream parts
in an overlap range of 2 mm to 7 mm. Ranges left between the overlap ranges
are 6 mm to 10 mm. The portions between the overlap ranges are set to have a
length that will not allow them to overlap with their respective weld beads.
As shown in FIG. 4, the guide plate 50 is obtained by press-forming a
steel sheet into a generally L shape. More specifically, the guide plate 50 is
comprised of an introducing part 51 provided at a position corresponding to
the
medium inlet 41b so as to cover the medium inlet 41b, a guide-forming part 52
extending from a lower end of the introducing part 51 laterally of the core
case 31,
and a flange part 53 integrally provided at a peripheral edge of the
introducing
inlet 51 and the guide-forming part 52 and adapted to be joined with the inner
peripheral surface part 31a of the core case 31.
The introducing part 51 bulging from the flange part 53 defines, jointly
with the guide-forming part 52, a closed cross-section between the inner
peripheral surface part 31a and the guide-forming part 52. At an upstream end
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part, the guide-forming part 52 has a plurality of guide apertures 52a, 52a
for
guiding the medium toward upstream of the heat exchange tube 34 (FIG. 2).
In the state in which the guide plate 50 is attached to the lower case half
41, as shown in FIG. 5, the medium introduced through the medium inlet 41b, as
shown by arrow (1), is guided into the inside of the core case 31 by the
guide-forming part 52. The medium thus guided into the core case 31 is caused
to flow through the guide apertures 52a, 52a toward upstream of the core case
31,
as shown by arrows (2), (2).
Turning back to FIG. 2, the introduced medium flows first through the
core case 31 toward upstream. Flowing through the upstream is the exhaust
gas that is yet to be heat-exchanged. Efficient heat exchange is enabled by
effectuating heat exchange between a non-heat-exchanged, high-temperature
exhaust gas and a non-heat-exchanged, low-temperature medium.
By causing the medium to flow upstream, it becomes possible to suppress
an increase in stress that arises by excessive heating of the upstream end
plate
32. This makes it possible to reduce a load applied to the heat exchanger 30
and
hence to prolong the life of the heat exchanger 30. The medium may boil by
heating it to a high temperature. By making the medium flow upstream, it
becomes possible to stably supply the medium upstream and hence to avoid
boiling of the medium. As a result, improved heat exchange efficiency is
provided.
Note also that the guide part is formed of the guide plate 50 of sheet
shape that defines a closed cross section between the plate 50 and the core
case
31 and that the upstream end part of the guide plate 50 is provided with the
guide apertures 52a. By this simple arrangement, it becomes possible to make
the medium flow upstream of the heat exchange tube 34.
As shown in (a) of FIG. 6, a heat exchanger 230, a known example for
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comparison, includes an upstream end plate 232 with an upstream wall part
232b extending from an upstream bottom surface part 232a toward upstream.
A downstream end plate 233 includes a downstream wall part 233b extending
from a downstream bottom surface part 233a toward downstream.
When the upstream wall part 232b is oriented toward upstream
(leftward), a top end part 232c of the upstream wall part 232b projects
forward
from the upstream end part 34a of the heat exchange tube 34 thereby increasing
the overall length of the heat exchanger 230.
The same discussion is applicable to the downstream end plate 233.
Namely, when the downstream wall part 233b is oriented toward downstream, a
top end part 233c of the downstream wall part 233b projects rearward from the
downstream end part 34b of the heat exchange tube 34 thereby increasing the
overall length of the heat exchanger 230.
Reference is now made to FIG. 6(b) illustrating the heat exchanger 30
according to the inventive embodiment. As shown in the Figure, the upstream
end plate 32 is comprised of the upstream bottom surface part 32a supporting
the heat exchange tube 34, and the upstream wall part 34a formed integrally
with and rising from the peripheral edge of the upstream bottom surface part
32a. The top end part 32c of the upstream wall part 32b is connected to the
core
case 31.
Since the top end part 32c of the upstream wall part 32b is oriented
toward downstream, the top end part 32c of the upstream wall part 32b is
positioned nearer to downstream than the upstream end part 34a of the heat
exchange tube 34. As a result, the overall length of the heat exchanger 30
becomes smaller (see a), whereby the heat exchanger 30 is downsized.
Note also that the top end part 32c of the upstream wall part 32b extends
rearward from the upstream end part 34a of the heat exchange tube 34 and is
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connected to the core case 31. As a result, the core case 31 is made shorter
by
the length of the upstream wall part 32b and hence downsized.
In the arrangement explained above, it is possible to make the medium
flow through an area enclosed by the upstream wall part 32b and the upstream
bottom surface part 32a. The core case 31 is downsized an amount equivalent to
the area and hence the heat exchanger 30 per se is downsized.
The same discussion is applied to the downstream end plate 33. Since
the top end part 33c of the downstream wall part 33b is oriented toward
upstream, the top end part 33c of the downstream wall part 33b is positioned
nearer to upstream than the downstream end part 34b of the heat exchange tube
34. As a result, the overall length of the heat exchanger 30 is decreased
(see 13)
to thereby downsize the heat exchanger 30.
Note additionally that the top end part 33c of the downstream wall part
33b extends forward from the downstream end part 34b of the heat exchange
tube 34 and is joined with the core case 31. The core case 31 is decreased in
length by the length of the downstream wall part 33b, whereby the core case 31
is downsized.
Note further that in the arrangement explained above, it is possible to
make the medium flow through an area enclosed by the downstream wall part
33b and the downstream bottom surface part 33a. This makes it possible to
downsize the core case 31 by the amount equivalent to the area and hence the
heat exchanger 30 as a whole.
As compared with the known example heat exchanger 230 (FIG. 6(a)), the
upstream side of the inventive heat exchanger 30 became shorter by a. The
same discussion is applicable to the downstream end plate 33. Compared to the
know example heat exchanger 230, the inventive core case 30 became shorter in
the downstream side by 6. To sum up, the heat exchanger 30 of the inventive
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embodiment is made shorter by a+13.
Referring also to FIG. 1, it will readily be appreciated that by employing
the heat exchanger 30 rendered compact as explained above, the exhaust heat
recovery apparatus 10 per se is made compact. It is desirable that freedom of
positioning of the exhaust heat recovery apparatus 10 be increased.
(Embodiment 2)
Discussion will be made next as to a second embodiment of the present
invention with reference to FIGS. 6 ¨ 11.
FIG. 7 illustrates in cross-section a heat exchanger according to a second
embodiment of the present invention in correspondence with FIG. 2. The heat
exchanger according to the second embodiment differs from the heat exchanger
shown in FIG. 2 in that the core case and the guide part are constructed
differently.
As shown in FIGS. 7 and 8, the heat exchanger 60 has a core case 61
which is comprised of a lower case half 71 having a generally U shape as seen
in
front elevation, an upper case half 72 having a generally U shape as seen in
front
elevation and coupled with the lower case half 71 from above, and a guide
plate
joined with a side surface and a bottom surface of the lower case half 71 from
outside.
The lower case half 71 is comprised of joining parts 71a, 71a joined with
the upstream end plate 32 and the downstream end plate 33, and a recessed part
71b provided between the joining parts 71a, 71a and recessed inwardly. The
recessed part 71b is comprised of tapered parts 71c, 71c extending inclinedly
from end parts of the joining parts 71a, 71a, and a planar part 71d extending
between the tapered parts 71a, 71c and parallel to the heat exchange tube 34.
The guide plate 80 is comprised of an inlet part 81 joined at a position
corresponding to a side surface of the lower case half 71, a guide forming
part 82
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extending from a lower end of the inlet part 81 in a direction of width of the
core
case 61, and a flange part 83 formed integrally with peripheral edges of the
inlet
part 81 and the guide forming part 82 and joined with an outer peripheral
surface part 61b of the core case 61.
The inlet part 81 is provided with a medium inlet (second heating
medium inlet) 81a for introducing the heating medium. The medium introducing
pipe 21 is connected to the medium inlet 81a.
The inlet part 81 and the guide forming part 82 jointly define a closed
cross section between them and an outer peripheral surface part 61b of the
core
case 61 to thereby provide a guide part 67. The upstream tapered part 71c is
formed with a guide aperture 71e for guiding the medium toward the upstream
of the heat exchange tube 34. In addition, a plurality of small apertures 71f,
smaller than the guide aperture 71e, is formed in the planar part 71d.
As shown in FIG. 9, the guide aperture 71e and the small apertures 71f
are formed at locations between corresponding layers of the heat exchange tube
34. It becomes possible to make the medium flow toward the interlayer space.
By thus making the medium flow directly to locations where flow passage areas
are large, the medium flows smoothly. As a result, heat exchange can be
effected efficiently.
Referring now to FIG. 10, the recessed part 71b is formed to run all
around the lower case half 71. The guide part 67 is constructed by covering
the
thus-formed outer peripheral surface part 61b of the lower case half 71 with
the
guide plate 80.
As can be appreciated from FIG. 11, the guide aperture 71e has a size
larger than those of the small apertures 71f. Thus, the medium fed in through
the medium inlet 81a, as shown by arrow (5), flows on toward upstream chiefly
through the guide aperture 71e, as shown by arrow (6). On the other hand, a
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remaining portion of the medium is introduced into the core case 61 through
the
small apertures 71f, as shown by arrow (7). The medium is introduce into the
core case 61 through the guide aperture 71e as a major stream and through the
small apertures 71f. As a result, it becomes possible for the medium to flow
into
the core case 61 in larger quantity, thereby enabling efficient heat exchange.
(Embodiment 3)
Explanation will be made next as to a third embodiment of the present
invention with reference to FIG. 12 wherein the construction of a heat
exchanger
according to the third embodiment is shown in cross section in correspondence
with the arrangement of FIG. 2.
As shown in FIG. 12, a heat exchanger 90 includes an upstream end plate
92 which is comprised of an end plate body 101 connected to the core case 31
and
having a generally U shape as viewed in cross section, and a support plate 102
connected to the end plate body 101 and supporting the heat exchange tube 34.
The end plate body 101 is comprised of an upstream bottom surface part
101a and an upstream wall part 101b formed integrally with and rising from a
peripheral edge of the upstream bottom surface part 101a. A rectangular
aperture 101c is formed in the upstream bottom surface part 101a. The support
plate 102 is joined with the peripheral edge of the rectangular aperture 101c.
The support plate 102 has a thickness smaller than that of the end plate 101.
The same discussion is applied to the downstream end plate 93. The
downstream end plate 93 is comprised of an end plate body 106 joined with core
case 31 and having a generally U shape as viewed in cross section, and a
support
plate 107 connected to the end plate body 106 for supporting the heat exchange
tube 34.
The end plate body 106 is comprised of a downstream bottom surface part
106a and a downstream wall part 106b formed integrally with and rising from
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the peripheral edge of the downstream bottom surface part 106a. A rectangular
aperture 106c is formed in the downstream bottom surface part 106a. A support
plate 107 is connected to the peripheral edge of the rectangular aperture
106c.
The support plate 107 has a thickness smaller than that of the end plate body
106.
The upstream end plate 92 and the downstream end plate 93 are
positioned differently in orientation. In the upstream end plate 92, the
upstream wall part 101b is extends from the upstream wall part 101a toward
upstream. As a result, a top end part 101d of the upstream wall part 101b
extends in a direction away from the core case 31. On the other hand, in the
downstream end plate 93, the downstream wall part 106b extends from the
downstream bottom surface part 106a toward upstream. As a result, a top end
part 106d of the downstream wall part 106b extends toward the core case 31.
Even when the top end part 106d of the downstream wall part 106b is
oriented toward upstream while the top end part 101d of the upstream wall part
101b is not oriented toward downstream as above, advantageous effects aimed at
by the present invention can be achieved. In other words, to an extent in
which
the top end part 106d of the downstream wall part 106b is oriented toward
upstream, the core case 31 can be downsized (see 13 of FIG. 6). This further
leads to downsizing of the heat exchanger 90.
Hot exhaust gas flows through the heat exchange tube 34 and the heat of
the gas causes the tube 34 to stretch. Since the thickness of the support
plate
102 is smaller than the thickness of the end plate body 101, the support plate
102
has smaller flexural rigidity than the end plate body 101. Thus, compared to
the end plate body 101, the support plate 102 is liable to bend. Since the
heat
exchange tube 34 is inserted to a portion liable to bend, stretch of the heat
exchange tube 34 can be absorbed by flexure or bend. This makes it possible to
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reduce a load applied to the heat exchange tube 34 and hence to prolong the
life
of the heat exchanger 90. The same goes to the downstream end plate 93.
It should also be appreciated that even when both the upstream end plate
92 and the downstream end plate 93 are oppositely oriented, the advantageous
effects of the invention can be produced (see a of FIG. 6). Namely, it is
possible
that the top end part 101d of the upstream end plate 92 be joined with the
core
case 31 while the top end part 106d of the downstream end plate 93 be disposed
to extend away from the core case 31 toward downstream.
Although the heat exchanger of the present invention has thus far been
described as being applied to an exhaust heat recovery apparatus, it may
readily
be applied to an EGR (Exhaust Gas Recirculation) air conditioner, a
cogeneration
system and a thermoelectric generation system. It may also be applied to other
systems than those as above in which heat exchange is carried out between an
exhaust gas and a medium.
It can also be appreciated by a person skilled in the art that part of the
heat exchange according to the third embodiment can be applied to the heat
exchanger according to the first embodiment. Namely, the embodiments can be
combined with one another as necessary.
17
