Note: Descriptions are shown in the official language in which they were submitted.
CA 022092~3 1997-07-04
FIELD OF THE INVENTION
The present invention relates to heat recovery systems
used in vehicles having an internal combustion engine and to heat
exchangers for use in such heat recovery systems.
Rr~ K~1JN-D OF THE INV ~ 1ON
It is well known in modern vehicles to heat the interior
of a vehicle and defrost the windows, during cold weather, by using
heat extracted from the vehicle's engine. The vehicle's cooling
system for the engine uses liquid coolant to perform such heat
extraction, which liquid coolant is passed through a heater core.
The heat from the coolant is transferred to air blown over the
heater core and into the passenger compartment of the vehicle.
During the first several minutes of operation of an
internal combùstion engine of a vehicle, the engine is still not
warmed up to a steady state operating temperature. Therefore, only
a minor amount of heat is produced. This is especially true for
diesel engines, which typically produce less heat at a given power
output. Accordingly, a vehicle having an internal combustion
engine is warmed very slowly, which is undesirable during cold
weather. Further, the defroster for the front window, and possibly
the defroster for the rear window, rely on hot air obtained from
CA 022092~3 1997-07-04
front window or rear window defrosted until the vehicle has warmed
up considerably. Thus, it may be unsafe to drive the vehicle
during cold weather before the vehicle has warmed up.
Additionally, an internal engine cannot provide full
power until a car is substantially warmed up. In some cases,
especially if the car is several years old, it may not be able to
be driven until the engine has warmed up to a nearly steady state
operating temperature, thus delaying the driving of the vehicle.
Another very important consideration is that of air
pollution. While an internal combustion engine is warming up, fuel
combustion is incomplete, thus causing a significant amount of air
pollution, especially with diesel engines. Indeed, many diesel
engines provide slightly complete fuel combustion even when warmed
up .
Another problem with large vehicles having an internal
combustion engine is that there is not enough heat produced to
properly warm the vehicle and to defrost the windows, even when the
engine is running at a steady state operatlng temperature. Such
deficiency of heated air at a steady state operating temperature is
known to be common for large vehicles with diesel engines where the
entire vehicle interior is being heated, such as school buses.
CA 022092~3 1997-07-04
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein the warm
up time of the internal combustion engine is decreased
significantly.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein fuel
combustion during warm up is improved.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein fuel
combustion of a diesel engine is improved even when warm.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein reduced
pollution is produced during warming up of the internal combustion
engine.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein heat is
provided in the vehicle more quickly after starting of the internal
combustion engine.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein no
external fuel source is used.
CA 022092~3 1997-07-04
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, that provides at
least sufficient heat for large vehicles, such as school buses.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, that helps
provide sufficient heat for large vehicles having diesel engines.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, that is
relatively inexpensive to manufacture and install.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, that may be
readily retrofitted onto a vehicle.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein heat is
absorbed from the exhaust system.
It is an object of the present invention to provide a
heat recovery system and heat exchanger therefor, wherein heat is
absorbed from the exhaust system using the liquid coolant of the
vehicle's cooling system.
CA 022092~3 1997-07-04
PRIOR ART
While various attempts have been made in the prior art to
address the above discussed problems, and indeed some sophisticated
systems exist overcome specific problems, none of the known prior
S art systems has addressed all of these problems.
United States Patent 4,087,047, to Wulf et al. discloses
a heating unit for automotive vehicles wherein a heat exchanger is
connected in heat absorbing relation with a portion of the exhaust
system, and uses a conventional bi-directional heat pipe to
transfer heat from the exhaust system to a second heat exchanger.
The second heat exchanger transfers heat to an auxiliary coolant
connecting line that is connected at one end to an outlet on the
engine block and is connected at its other end to the existing
cooling system at a heater controller. This system is unduly
expensive as two heat exchangers, a heat pipe and an auxiliary
connecting line for the coolant system are all required. Further,
heat transfer from the exhaust system to the liquid coolant in the
cooling system is inefficient as the first heat exchanger, heat
pipe, and a second heat exchanger are used. The first heat
exchanger that the exhaust system therefore must be extremely
efficient for the system to be properly effective.
U.S. Patent 3,618,854 to Frank, discloses a vehicle
heating system employing a critical point heat pipe. A vaporizable
CA 022092~3 1997-07-04
heat-pipe-working fluid having a critical point temperature
substantially at the desired reference temperature transports heat
from the heat source to the heat sink by means of the heat pipe
when the temperature of the heat sink is below the reference
temperature, and automatically terminates the heat exchange when
the temperature of the heat sink reaches the reference temperature.
The automatic termination of the heat exchange being the direct
result of the properties of the heat-pipe-working fluid. This
vehicle heating system does not use the coolant from the engine's
cooling system and therefore does not improve engine warm-up time
and does not improve combustion during engine warm up, and does not
use heat from the vehicles exhaust.
U.S. Patent 4,146,176 to Beauvais et al . discloses an
exhaust gas heating system utilizing a heat pipe. The heat pipe is
connected at its evaporator end to a heat exchanger in the
vehicle's exhaust system. The condenser end of the heat pipe is
provided with heating fins disposed within the conventional heater
case of a vehicle, so as to heat the vehicle. This exhaust gas
heating system does not use the coolant from the engine's cooling
system and therefore does not improve engine warm-up time and does
not improve combustion during engine warm up.
U.S. Patent 4,775,102 to Negishi et al. discloses a space
heating system utilizing engine exhaust heat, wherein a heat
absorbing element is disposed within the exhaust system of a
CA 022092~3 1997-07-04
vehicle to absorb heat from the exhaust gases. A working fluid
passage leads from the heat absorbing element to an expanded
section that surrounds a second pipe. The working fluid passage
continues on through a check valve device into a working fluid
reservoir tank, and the leads back through a return flow pipe and
another check valve to the origin of the working fluid passage at
the heat absorbing element. This space heating system does not use
the coolant from the engine's cooling system and therefore does not
improve engine warm-up time and does not improve combustion during
engine warm up.
U.S. Patent 4,958,766 to Toth et al. discloses an
appliance for heating a motor vehicle with an internal combustion
engine. A heat accumulator is in heat transfer connection with the
exhaust pipe of the vehicle and with the space to be heated. The
essential feature of the invention is that the heat accumulator is
directly connected with an extended cooling circuit and has a
circulating pump operating independently from the engine, and built
in to an extended coolant circuit. The heat accumulator
accumulates heat from the exhaust gases of the engine during
ongoing engine operation, and the heat stored therein is used to
pre-heat the coolant of the engine and to provide heat into the
passenger compartment the vehicle, prior to starting of the engine.
This appliance for heating a motor vehicle does not use the coolant
from an engine's exhaust system to extract heat from the vehicle's
exhaust.
CA 022092~3 1997-07-04
U.S. Patent 5,398,747 to Miaoulis discloses an automotive
vehicle auxiliary component heating method and system that uses
lithium bromide as a heat exchange medium in a heat exchanger to
extract heat from the exhaust system of a vehicle. A separate
water evaporator and condenser circuit is used to heat various
components of the vehicle before they are up to steady-state
operating temperature, and to heat the interior of the vehicle.
This auxiliary component heating method and system does not use the
coolant from the engine's cooling system and therefore does not
improve engine warm-up time and does not improve combustion during
engine warm up.
U.S. Patent 4,705,214 to Johnson discloses an independent
exhaust gas heating system for heating a motor vehicle passenger
compartment. The independent exhaust gas heating system comprises
a surge tank feeding a heat transfer medium to a pump, which
circulates fluid through a heater core, a heat exchanger and a
waste heater core, if necessary. The heat exchanger is connected
to an engine exhaust system for heating the circulating medium by
the engine exhaust gases. The heat system is completely
independent of the vehicle's cooling system and therefore can be
used in a vehicle not having a liquid based cooling system. This
independent exhaust gas heating system does not use the coolant
from the engine's cooling system and therefore does not improve
engine warm-up time and does not improve combustion during engine
warm upO
-
CA 022092S3 1997-07-04
U.S. Patent 4,010,895 to Kofink et al . discloses a system
for pre-heating a water-cooled vehicle engine and interior of the
vehicle. A heating device powered by a liquid fuel generates heat
before starting of the internal combustion engine, to pre-heat the
internal combustion engine and the interior of the vehicle. This
system for pre-heating a water-cooled vehicle engine and interior
does not use heat from a vehicle's exhaust.
SU~IARY OF THE INVENTION
In accordance with one aspect of the present invention,
there is disclosed a heat exchanger for use in a heat recovery
system used in a vehicle for warming the vehicle during cold
weather. The heat exchanger comprises a fluid retaining main body
member having a first end, a second end, a main longitudinal axis
extending from the first end to the second end, and a substantially
hollow interior. An inlet is mounted on the main body member in
fluid communication with the substantially hollow interior adjacent
the first end of the main body member. An outlet is mounted on the
main body member in fluid communication with the substantially
hollow interior adjacent the second end of the main body member.
An exhaust flow passageway having an inlet end and an outlet end in
fluid communication one with the other, for in-line connection with
a vehicle exhaust system, is mounted in the main body member in
throughpassing relation from the first end to the second end such
that the hollow interior of the main body member substantially
CA 022092~3 1997-07-04
surrounds at least a portion of the exhaust flow passageway in heat
transfer relation. In use, a heat transfer fluid ingresses the
main body member through the inlet, flows from the first end to the
second end of the main body portion through the hollow interior
whereat heat from the exhaust flow passageway is absorbed, and
egresses through the outlet.
In accordance with another aspect of the present
invention, there is disclosed a heat recovery system for use in a
vehicle having a internal combustion engine and an engine cooling
system using liquid coolant flowing through a circuit from the
internal combustion engine to a heater in the vehicle, for rapidly
heating the liquid coolant during cold weather. The heat recovery
system comprises a heat exchanger having an exhaust flow passageway
adapted for in-line connection with a vehicle exhaust system, a
main body portion having a substantially hollow interior and being
positioned in heat exchange relation with the exhaust flow
passageway, an inlet connected in fluid communication to a coolant
outlet of an internal combustion engine so as to receive liquid
coolant therefrom, and an outlet connected in fluid communication
to a coolant inlet of a heater within the vehicle, so as to supply
heated liquid coolant to the heater, and ultimately back to the
internal combustion engine.
Other advantages, features and characteristics of the
present invention, as well as methods of operation and functions of
- 10 -
-
CA 022092s3 1997-07-04
the related elements of the structure, and the combination of parts
and economies of manufacture, will become more apparent upon
consideration of the following detailed description and the
appended claims with reference to the accompanying drawings, the
latter of which is briefly described hereinbelow.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features which are believed to be
characteristic of the heat exchanger and the heat recovery system,
according to the present invention, for use in a vehicle having an
internal combustion engine, as to the invention's structure,
organization, and use, together with further objectives and
advantages thereof, will be better understood from the following
drawings in which a presently preferred embodiment of the invention
will now be illustrated by way of example. It is expressly
understood, however, that the drawings are for the purpose of
illustration and description only, and are not intended as a
definition of the limits of the invention. In the drawings:
Figure 1 is a cut-away top plan view of the preferred
embodiment of the heat exchanger according to the present
invention;
Figure 2 is a cross-sectional view taken along section
line 2-2 of Figure l;
CA 022092~3 1997-07-04
Figure 3 is a simplified pictorial view of a first
embodiment of the heat recovery system according to the present
invention; and
Figure 4 is a simplified pictorial view of a second
embodiment of the heat recovery system of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made to Figure 1, which shows the
preferred embodiment heat exchanger of the present invention, as
indicated by the general reference numeral 20. The heat exchanger
20 is for use in a heat recovery system used in a vehicle, which
heat recovery system is for warming a vehicle during cold weather,
as will be discussed in greater detail subsequently. The heat
exchanger 20 may be used with the heat recovery system of the
present invention as depicted in Figure 2, or with other
conventional heat recovery systems, as long as the heat exchanger
is installed in place in an exhaust system of a vehicle,
preferably close to the engine end of the exhaust system so as to
receive the exhaust gases when they are their hottest.
The heat exchanger 20 comprises a substantially
cylindrical main body member 30 having first end 31 and a second
end 320 Preferably, the main body member 20 is elongate so as to
increase the heat transfer area in the heat exchanger 20 and has a
- 12 -
CA 022092~3 1997-07-04
longitudinal axis "A" extending from the first end 31 to the second
end 32. The main body member 30 defines a substantially hollow
interior 34 in which heat transfer fluid 70 is retained and flows
through, as will be discussed in greater detail subsequently. The
main body member 30 must of course be fluid retaining so as to
preclude the unwanted escape of the heat transfer fluid 70
therefrom.
An inlet 40 comprises an elongate inlet tube 42 mounted
on the main body member 30 adjacent the second end 32 thereof. The
elongate inlet tube 42 extends along the substantially hollow
lnterior 34 of the main body member 32 and terminates near the
first end 31 thereof. The inlet 40 is in fluid communication at
its ingress end 44 with a source of heat transfer fluid 70 and in
fluid communication at its egress end 46 with the substantially
hollow interior 34 of the main body 30 adjacent the first end 31
thereof.
An outlet member 50 is mounted on the main body member 30
and has an ingress end 52 in fluid communication with the
substantially hollow interior 34 of the main body 30 adjacent the
second end 32 thereof, and also has an egress end 54 in fluid
communication with the heater core of the vehicle that the heat
exchanger 20 is installed in.
- 13 -
CA 022092~3 1997-07-04
A substantially straight exhaust flow passageway 60,
preferably in the form of a tubular pipe, is mounted in the main
body member 30 so as to be substantially centrally disposed therein
and so as to be oriented along the main longitudinal axis "A". The
exhaust flow passageway 60 may also be non-straight -- or in other
words bent, or even folded -- for a variety of reasons including
muffling of noise, increasing its size of contact surface in the
main body member 30, and so on. The exhaust flow passageway 60 has
an inlet end 62 and an outlet end 64 in fluid communication one
with the other. The inlet end 62 extends outwardly from the first
end 31 of the main body member 30 and is connected in exhaust
receiving relation to the exhaust system of a vehicle, preferably
directly to the exhaust manifold. Similarly, the outlet end 64
extends outwardly from the second end 32 of the main body member 30
and is connected in exhaust emitting relation to the remainder of
the exhaust system of a vehicle. Conventional muffler clamps (not
shown) may be use to securely connect the exhaust flow passageway
60 to an exhaust system of a vehicle.
The exhaust flow pipe 60 is mounted in the main body
member 30 and throughpassing relation from the first end 31 to the
second end 32 such that the hollow interior 34 of the main body
member substantially surrounds the exhaust flow passageway 60 in
heat transfer relation. Exhaust gases flow in the exhaust flow
passageway 60 from the second end 32 to the first end 31 of the
hollow interior 34 of the main body member 30.
- 14 -
CA 022092~3 1997-07-04
In use, the heat transfer fluid 70 ingresses into the
main body member 30 through the inlet 40, by flowing into the
ingress end 44 of the elongate inlet tube 42, as indicated by arrow
~B", through the elongate inlet tube 42, as indicated by arrow "C",
and out of the egress end 46 of the elongate inlet tube 42, as
indicated by arrow "D", so as to be adjacent first end 31 of the
main body member 30. The heat transfer fluid 70 flows from the
first end 31 to the second end 32 of the main body member 30
generally around the exhaust flow passageway 60, as indicated by
arrows "E", whereat heat from the exhaust flow pipe 60 is absorbed.
The heat transfer fluid 70 then egresses through the outlet 50, as
indicated by arrow "F". It can be seen that there is no baffling
disposed between the first end 31 and the second end 32 of the main
body member 30. By omitting such baffling, the chance of
cavitation of the heat transfer fluid 70 is minimized.
Reference will now be made to Figure 3 which shows a
first preferred embodiment of the heat recovery system 80 of the
present invention for use in a vehicle having an internal
combustion engine 82 and a conventional engine cooling system, as
indicated by the general reference numeral 84. The engine cooling
system 84 employs a coolant pump 86 to circulate the coolant 88
within the engine 82. Above a predetermined temperature, a
thermostat 90 opens and permits the liquid coolant 88 to flow past
the thermostat 90, exit the engine 82 through a liquid coolant
outlet 92 and pass through a circuit 94 to the radiator 96. The
CA 022092~3 1997-07-04
coolant pump 86 draws the liquid coolant 88 back from the radiator
92. An essentially separate circuit 97 permits flow of the liquid
coolant 88 from another liquid coolant outlet 98 and through a
heater core 99 in the vehicle, whereat the liquid coolant 88
provides heat to the interior of the vehicle. Again, the coolant
pump 86 draws the liquid coolant 88 back from the heater core 99.
The heat recovery system of the present invention, as
indicated by the general reference numeral 80, comprises a heat
exchanger 102 having an exhaust flow pipe 104 adapted for in-line
connection with a vehicle exhaust system 106. A main body portion
108 has a substantially hollow interior 110 and is positioned in
heat exchange relation with the exhaust flow pipe 104. An inlet
112 is connected in fluid communication to a liquid coolant outlet
114 of the internal combustion engine 82 so as to receive liquid
coolant 88 therefrom. An outlet 116 is connected in fluid
communication with the inlet line of the coolant pump 86, so as to
supply heated liquid coolant 88 to the engine 82. As depicted in
Figure 4, the heat recovery system 80 is connected to the internal
combustion engine 82 essentially in parallel with the heater core
99. As is readily apparent, the heat recovery system 80 as
disclosed is for use during cold weather, for rapidly heating the
liquid coolant 88 and returning it directly to the internal
combustion engine 82.
- 16 -
CA 022092~3 1997-07-04
Reference will now be made to Figure 4 which shows a
second preferred embodiment of the heat recovery system 80 of the
present invention for use in a vehicle having an internal
combustion engine 82 and a conventional engine cooling system, as
indicated by the general reference numeral 84. The engine cooling
system 84 is identical to the one in Figure 3 and like reference
numerals will be used to indicate like parts. Further, the heat
recovery system of the present invention, as indicated by the
general reference numeral 80, is identical to the one in Figure 3
and like reference numerals will be used to indicate like parts.
However, it can be seen in Figure 4, that the outlet 116 of the
heat exchanger 102 is connected in fluid communication with the
heater core 99. As depicted in Figure 4, the heat recovery system
80 is connected to the internal combustion engine 82 essentially in
series with the heater core 99. As is readily apparent, the heat
recovery system 80 as disclosed is for use during cold weather, for
rapidly heating the liquid coolant 88 and passing it through the
heater core 99 before returning it to the internal combustion
engine 82.
In the first and second preferred embodiments, as
depicted in figures 3 and 4, the inlet 112 of the heat exchanger
102 is connected in non-valved relation to the liquid coolant
outlet 114 of the internal combustion engine 82, such that the flow
of liquid coolant 88 through the heat exchanger 102 is non-
divertible. Such a non-divertible connection would be acceptable
CA 022092~3 1997-07-04
in large trucks having diesel engines, such as school buses, where
a large amount of heat is required at all times during cold months,
and lowers the cost of manufacturing and installation, and also
simplifies the installation process. The thermostat 90 and the
radiator of the cooling system 84 would merely operate in a
conventional manner once the liquid coolant reaches a predetermined
temperature. In testing during cold winter months, it has been
found with the heat recovery system 80 and the heat exchanger 20 of
the present invention, that the radiator thermostat switches into
cooling mode in about half of the time as compared to not having
the same installed.
It can be seen that the present invention provides many
advantages over the prior art. Namely, the warm up time of the
internal combustion engine is decreased significantly; fuel
combustion during warm up is improved; fuel combustion of a diesel
engine is improved even when warm; reduced pollution is produced
during warming up of the internal combustion engine; heat is
provided in the vehicle more quickly after starting of the internal
combustion engine; no external fuel source is used; sufficient heat
is provided for large vehicles, such as school buses, even those
having diesel engines; the present invention is relatively
inexpensive to manufacture and install, and may be readily
retrofitted onto a vehicle; heat is absorbed from the exhaust
system using the liquid coolant of the vehicle's cooling system,
and thus a non-renewable resource is effectively used.
- 18 -
CA 022092~3 1997-07-04
The present invention is applicable to various types of
vehicles, such as automobiles, trucks, buses, boats, airplanes, and
so on, and is also applicable in industrial applications in
conjunction with stationary internal combustion engines.
Other variations of the above principles will be apparent
to those who are knowledgeable in the field of the invention, and
such variations are considered to be within the scope of the
present invention. Further, other modifications and alterations
may be used in the design and manufacture of the present invention
without departing from the spirit and scope of the accompanying
claims.
- 19 -
