Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
heat exchanger for a motor vehicle exhaust
NAME ( S) OF INVENTOR ( S):
Easton Bennett
FIELD OF THE INVENTION
The present invention relates to a heat exchanger for
motor vehicle exhaust
BACKGROUND OF THE INVENTION
In a prior United States Patent Application, now United
States Patent 5,799,632, Easton Bennett taught how to improve
heat transfer from a motor vehicle exhaust through the use of
a tubular body having fluid impervious sidewalls formed out of
a single length of conduit wound in a spiral coil. This
structure brought the exhaust in closer contact with fluid to
which a heat transfer was to be effected.
Experience has now shown that there are a variety of types
of motor vehicles, the needs of which differ. In some makes
of gasoline powered automobile the problem is one of heat
management. A build up of heat occurs behind the catalytic
converter and there exists a need to dissipate that heat. In
contrast, diesel engines have a comparatively low heat
production and there is a need to obtain maximum heat transfer
from the exhaust gases that pass through the heat exchanger.
In each case, there is a common problem of maximizing the rate
of heat transfer, while avoiding heat build ups which could
cause damage to the exhaust system or the engine.
SITNIIKARY OF THE INVENTION
What is required is a heat exchanger for a motor vehicle
exhaust that has further enhanced heat transfer capability.
According to one aspect of the present invention there is
provided a heat exchanger for a motor vehicle exhaust including
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an outer tubular body and an inner tubular body. The outer
tubular body has peripheral sidewalls, an interior cavity, a
first end and a second end. The inner tubular body has fluid
impervious sidewalls formed out of a single length of conduit
wound in a spiral coil. The spiral coil has an exterior
surface and an interior surface. The inner tubular body is
disposed within the interior cavity of the outer tubular body
spaced from the peripheral sidewalls. This provides a first
flow channel between the exterior surface of the inner tubular
body and the peripheral sidewalls of the outer tubular body,
and a second flow channel along the interior surface of the
inner tubular body. The conduit of the spiral coil has an
inlet end and an outlet end, whereby fluid is circulated
through the coil. An exhaust pipe connection is provided at
each of the first end and the second end of the outer tubular
body, whereby exhaust from an exhaust pipe is diverted through
the interior cavity of the outer tubular body.
With the heat exchanger, as described above, each side of
the spiral transfer coil is exposed to exhaust gases which
serves to improve the heat transfer rate.
Although beneficial results may be obtained through the
use of the heat exchanger for a motor vehicle exhaust, as
described above, even more beneficial results may be obtained
when the outer tubular body has fluid impervious sidewalls
formed out of a single length of conduit wound in a spiral
coil, the conduit of the spiral coil having an inlet end and
an outlet end, whereby fluid is circulated through the coil.
With this version of the heat exchanger there can be two
streams of fluid being circulated through both the inner coil
and the outer coil. This increases the volume of fluid being
circulated and, thereby, improves the rate of heat transfer.
Although beneficial results may be obtained through the
use of the heat exchanger for a motor vehicle exhaust, as
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described above, the more spiral coils provided the greater the
volume of fluid that can be used for heat exchange. It is also
preferable that both the inside surface and the outside surface
of each spiral coil be exposed to hot exhaust gases. Even more
beneficial results may, therefore, be obtained when there are
several concentric inner tubular bodies.
Although beneficial results may be obtained through the
use of the heat exchanger for a motor vehicle exhaust, as
described above, the transfer rate is also related to the rate
of flow of hot exhaust gases through the interior cavity of the
outer tubular body. Even more beneficial results may,
therefore, be obtained when the inner tubular body has a spiral
baffle positioned in the second flow channel.
With this version of the heat exchanger, the spiral baffle
slows down the axial flow of exhaust gases, thereby increasing
the time over which heat transfer can take place. This feature
is of greater importance with diesel engines, where the heat
of the exhaust gases is not as extreme as with gasoline
engines.
According to another aspect of the invention there is
provided in combination a hydrocarbon fuelled engine; an
exhaust system including a plurality of exhaust pipes; a closed
loop fluid circulation conduit through which circulates one of
lubricant or coolant; and a heat exchanger for a motor vehicle
exhaust as described above.
Although beneficial results may be obtained through the
use of the combination, as described above, lubricant and
coolant are both sensitive to heat. If they are heated above
threshold temperatures they start to deteriorate. Even more
beneficial results may, therefore, be obtained when a
temperature sensor coupled to a temperature actuated control
valve is provided on the closed loop fluid circulation conduit.
The control valve is closed to stop flow through the heat
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exchanger upon the temperature of fluid in the closed loop
circulation conduit as sensed by the temperature sensor
exceeding a preset temperature threshold actuation temperature
of the control valve.
Although beneficial results may be obtained through the
use of the combination, as described above, when the control
valve closes there is a danger that fluid may be trapped within
the heat exchanger. Even more beneficial results may,
therefore, be obtained when a pump is connected to the outlet
end of the conduit forming the spiral coil, whereby fluid is
pumped from the spiral coil after the control valve has closed
to stop further flow through the heat exchanger.
Although beneficial results may be obtained through the
use of the combination, as described above, heat results in
expansion of most fluids. Even more beneficial results may,
therefore, be obtained when an overflow drain line is connected
to the closed loop fluid circulation conduit, whereby excess
fluid is diverted from said closed loop fluid circulation
conduit. It is preferred that an overflow container is
connected to a remote end of the drain line to maintain the
integrity of the closed loop system and prevent environmental
contamination.
Although beneficial results may be obtained through the
use of the combination, as described above, should the pump
fail and fluid become trapped within the heat exchanger
pressure in the closed loop circulation conduit will rise.
Even more beneficial results may, therefore, be obtained when
a pressure relief valve is provided on the closed loop fluid
circulation conduit thereby providing relief against pressure
build up within said closed loop fluid circulation conduit.
Although beneficial results may be obtained through the
use of the combination, as described above, there are various
places along the exhaust system where the heat exchanger can
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be positioned. The most extreme heat problem in the exhaust
system tends to be at the catalytic converter. Even more
beneficial results may, therefore, be obtained when the exhaust
system includes a catalytic converter and the heat exchanger is
5 connected to the exhaust system downstream or and immediately
adjacent to the catalytic converter.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is a schematic diagram of a first embodiment heat
exchanger for a motor vehicle exhaust constructed in accordance
with the teachings of the present invention combined in
combination with a motor vehicle exhaust.
FIGURE 2 is side elevation, in section, of a second
embodiment of heat exchanger.
FIGURE 3 is a side elevation, in section, of a third
embodiment of heat exchanger.
FIGURE 4 is a side elevation, in section, of a fourth
embodiment of heat exchanger.
FIGURE 5 is a side elevation, in section, of a fifth
embodiment of heat exchanger.
FIGURE 6 is a side elevation, in section, of a sixth
embodiment of heat exchanger.
FIGURE 7 is a schematic diagram of a combination of an
engine and an exhaust system with a heat exchanger.
FIGURE 8A is a schematic diagram of a two-way shut off
valve in the on position.
FIGURE 8B is a schematic diagram of a two-way shut off
valve in the off position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Several preferred embodiments of heat exchanger for a
motor vehicle exhaust will hereinafter be described. A first
embodiment, generally identified by reference numeral 10, will
be described with reference to FIGURE 1. A second embodiment,
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generally identified by reference numeral 12, will be described
with reference to FIGURE 2. A third embodiment, generally
identified by reference numeral 13, will be described with
reference to FIGURE 3. A fourth embodiment, generally
identified by reference numeral 14, will be described with
reference to FIGURE 4. A fifth embodiment, generally
identified by reference numeral 16, will be described with
reference to FIGURE S. A sixth embodiment, generally
identified by reference numeral 17, will be described with
reference to FIGURE 6. A combination of a hydrocarbon fuelled
engine and an exhaust system including a plurality of heat
exchangers which can be of any one of the first, second, third,
fourth, fifth or sixth embodiments above and a plurality of
exhaust pipes will be described with reference to FIGURES 7, 8A
and 8B.
Referring to FIGURE 1, first embodiment of heat exchanger
10 for a motor vehicle exhaust comprises an outer tubular body
and an inner tubular body 22. Outer tubular body 20 has
20 peripheral sidewalls 24, an interior cavity 26, a first end 28
and a second end 30. Inner tubular body 22 has fluid
impervious sidewalls 31 formed out of a single length of
conduit wound in a spiral coil 32 which has an exterior surface
34 and an interior surface 36. Inner tubular body 22 is
disposed within the interior cavity 26 of outer tubular body 20
so that spiral coil 32 is spaced from the peripheral sidewalls
24, thereby providing a first flow channel 38 between the
exterior surface 34 of the inner tubular body 22 and the
peripheral sidewalls 24 of the outer tubular body 20, and a
second flow channel 40 along the interior surface 36 of the
inner tubular body 22. The directions of flow of fluids in
first flow channel 38 is shown by arrows 42 and the direction
of flow in second flow channel 40 is shown by arrows 44. The
conduit of the spiral coil 32 has an inlet end 46 and an outlet
end 48 whereby fluid is circulated through coil 32 in the
direction shown by the arrows 50. Exhaust pipe connections 52
and 54 at each of the first end 28 and the second end 30 of the
outer tubular body 20 respectively permit exhaust 56 from an
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exhaust pipe 58 to be diverted through interior cavity 26 of
outer tubular body 20 before venting in the direction shown by
arrow 60. When heat exchanger 10 is not in operation, fluid
may be pumped from spiral coil 32 via conduit 61.
With reference to FIGURE 2, second embodiment of heat
exchanger 12 for a motor vehicle exhaust includes an outer
tubular body 62 and an inner tubular body 64 formed out of a
single length of conduit 66 wound in a concentric double spiral
coil 68 and 69. Conduit 66 has fluid impervious sidewalls 70,
an inlet end 72 and an outlet end 74, whereby fluid is
circulated through the spiral coils 68 and 69 in the direction
shown by the arrow 76. When heat exchanger 12 is not in
operation, fluid may be pumped from spiral coils 68 and 69 via
conduits 78 and 79.
With reference to FIGURE 3, third embodiment of heat
exchanger 13 is substantially similar in construction to heat
exchanger 12, illustrated in FIGURE 2. However, instead of a
single length of conduit 66 wound in a concentric double spiral
coil 68 and 69 there are two separate and distinct spiral coils
268 and 269 arranged concentrically. Each of coils 268 and 269
has a separate inlet, 272a and 272b, respectively and a
separate outlet, 274a and 274b, respectively. Fluid is
circulated through spiral coil 268 in the direction shown by
the arrow 276a. Fluid is circulated through spiral coil 269 in
the direction shown by the arrow 276b. When heat exchanger 13
is not in operation, fluid may be pumped from spiral coils 268
and 269 via conduits 278 and 279, respectively.
With reference to FIGURE 4, fourth embodiment of heat
exchanger 14 for a motor vehicle exhaust has an inner tubular
body 80 and an outer tubular body 82. Inner tubular body 80
has fluid impervious peripheral sidewalls 84, an interior
cavity 86, a first end 88 and a second end 90. Sidewalls 84
have an interior surface 92 and an outer surface 94. Outer
tubular body 82 has fluid impervious sidewalls 95 and is formed
out of a single length of conduit wound in a spiral coil 96.
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Outer tubular body 82 is disposed concentrically around inner
tubular body 80 so that spiral coil 92 is wound around the
peripheral sidewalls 84. Inner tubular body 80 has a spiral
baffle 98 positioned in the flow channel in interior cavity 86,
with flow in the direction indicated by the arrow 100. Outer
tubular body 82 has an inlet end 102 and an outlet end 104
whereby fluid is circulated through the spiral coil 92 in the
direction shown by the arrow 106. When heat exchanger 14 is
not in operation, fluid may be pumped from spiral coil 92
through conduit 107.
With reference to FIGURE 5, fifth embodiment of heat
exchanger 16 for a motor vehicle exhaust has several concentric
inner tubular bodies 108 and 109. Tubular bodies 108 and 109
are formed out of a single length of conduit 112 wound in
concentric multiple spiral coils 110 and 111. Conduit 112 has
an inlet end 114 and an outlet end 116 whereby fluid is
circulated through spiral coils 110 and 111 in the direction
shown by the arrows 118 and 119. When heat exchanger 16 is not
in operation, fluid may be pumped from spiral coils 110 and 111
through conduits 120 and 122.
With reference to FIGURE 6, sixth embodiment of heat
exchanger 17 for a motor vehicle exhaust is substantially
similar in construction to heat exchanger 16, illustrated in
FIGURE S. However, instead of a single length of conduit 112
wound in concentric multiple spiral coils 110 and 111, there
are two separate and distinct spiral coils 210 and 211 arranged
concentrically. Coils 210 and 211 have separate inlets 214a
and 214b, respectively and separate outlets 216a and 216b,
respectively. Fluid is circulated through the spiral coil 210
in the direction shown by the arrows 218 and 219. Fluid is
circulated through the spiral coil 211 in the direction shown
by the arrows 224 and 226. When heat exchanger 17 is not in
operation, fluid may be pumped from spiral coils 210 and 211
through conduits 228 and 230.
With reference to FIGURE 7, at least one heat exchanger
124 selected from heat exchanger 10, heat exchanger 12, heat
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exchanger 13, heat exchanger 14, heat exchanger 16 or heat
exchanger 17 is used in combination with a hydrocarbon fuelled
engine 126, and an exhaust system 128. Exhaust system 128
includes a plurality of exhaust pipes 130 and 132, and a
catalytic converter 136. The system is capable of being used
to heat either lubricant or coolant. Coolant circulates
through closed loop fluid recirculation system 134 to radiator
137 or heater core 139. The coolant is heated to improve
operation of heater core 139. In summer operation, the
emphasis is dissipating heat build in the vicinity of the
catalytic converter 136. Engine lubricant can similarly be
passed through closed loop fluid recirculation conduit 134.
The heating of engine lubricant improves the operation of
engine 126 during periods of extremely cold weather.
Exhaust heat exchanger 124 is secured at each of a first
end 138 and a second end 140 of an outer tubular body 142 to
exhaust pipes 130 and 132, whereby exhaust from the exhaust
system 128 is diverted through the interior cavity 144 of outer
tubular body 142. The direction of flow of the exhaust is
indicated by arrows 145.
A temperature sensor 146 located in engine 126 is coupled
to a temperature actuated two-way control valve 148 provided on
closed loop fluid circulation conduit 134. A switch 149 is
used remotely to set two-way control valve 148 to either an
"off" position or an "on" position. The direction of fluid
flow in closed loop fluid circulation conduit 134 is indicated
by arrows 150. Control valve 148 is closed to stop flow
through heat exchanger 124 upon the temperature of fluid in
closed loop circulation conduit 134 as sensed by temperature
sensor 146 exceeding a preset temperature threshold actuation
temperature of control valve 148. A pump 152 is connected to
the outlet end of closed loop fluid recirculation conduit 134,
whereby fluid is pumped from spiral coil 154 after control
valve 148 has closed to stop further flow through heat
exchanger 124. An overflow drain line 156 is connected to
closed loop fluid circulation conduit 134, whereby excess fluid
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is diverted from said closed loop fluid circulation conduit 134
to a fluid overflow container 158. An overflow drain line 160
is connected to access port 162 of radiator 137, whereby excess
fluid is drained from radiator 137 to overflow container 158.
5 The level of the fluid in overflow container 158 is indicated
by dashed line 164. A pressure relief valve 166 is provided on
closed loop fluid circulation conduit 134 thereby providing
relief against pressure build up within said closed loop fluid
circulation conduit 134. Heat exchanger 124 is connected to
10 exhaust system 128 downstream from and preferably immediately
adjacent to catalytic converter 136.
Referring to FIGURES 8A and 8B, two-way shut off valve 148
can be set to either of an "on" position 168 or an "off"
position 170 using switch 149. Referring to FIGURE 8A, when
two-way shut off valve 148 is in the on position 168 a barrier
172 at a junction 173 between sections 174 and 176 of closed
loop fluid recirculation conduit 134 is positioned to prevent
flow of fluid from conduit section 174 to conduit section 176,
thereby causing the fluid to flow through the entire length of
closed loop fluid circulation conduit 134. The direction of
flow of the fluid is indicated by arrows 178. Referring to
FIGURE 8B, when two-way shut off valve 148 is in the off
position 170 barrier 172 at junction 173 is positioned to
permit flow of fluid from conduit section 174 to conduit
section 176. The direction of flow of fluid in conduit
sections 174 and 176 is indicated by arrow 180. When two-way
shut off valve 148 is in the off position sections 182 and 184
of closed loop fluid recirculation conduit 134, safety relief
valve 166 and coil 154 of heat exchanger 124 are isolated from
the remaining sections of closed loop fluid recirculation
conduit 134. Consequently there is no flow of fluid in conduit
sections 182 and 184 or coil 154.
The present invention can be used to preheat engine oil,
hydraulic oil, transmission oil or fluids used in the heater.
The use of multiple coils enables two or more fluid streams to
be preheated at the same time. This provides a number of
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benefits. It reduces interior heat up time and generally
improves interior heating. It reduces engine warm up time and
generally increases the operating temperature of the engine for
winter use. It reduces fuel consumption during warm up, by
reducing engine and interior warm up time. It reduces
emissions on cold start up.
A separate problem is the build up of heat that is
occurring in automotive exhaust systems in the area of the
catalytic converter. To dissipate such heat build up, a liquid
can be run through multiple coils positioned in the exhaust.
In hot weather operation, the sole purpose of the multiple
coils can be heat dissipation and the liquid circulated can be
dedicated to that purpose. The liquid can be passed through
cooling fins or other such means to release the heat from the
liquid prior to recirculation through the multiple coils.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment without
departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
