CA1140821A - Fuel saving device - Google Patents

Abstract

ABSTRACT

FUEL SAVING DEVICE
A fuel saving device for internal combustion engines which connects between the carburetor and the engine intake manifold, and includes means for heating and turbulating the air-fuel mixture flow as it flows from the carburetor to the engine.

Description

8Zl The present invention relates to a fuel saving device for internal combustion engines.
During normal operation of a typical gasoline powered automobile engine, a standard carburetor intro-duces by means of jets a fine liquid fuel spray-type mist into a filtered air stream and delivers the resulting air-fuel mixture to the engine combustion chamber via the intake manifold of the engine. As is well known, efficient combustion of the fuel in the combustion chamber will depend upon the size of the liquid fuel particles in the air-fuel mixture. The larger the particles, the slower will be the combustion process, the reason being that hydrocarbon fuels such as gasoline can only be burned (oxidized) in vapor form -- hence, the combustion of an air-fuel mixture can only occur down to the evaporating surface of the fuel particles. Accordingly (and presupposing an adequate supply of oxygen from the air), it will be apparent that the speed of the combustion process will be enhanced to the extent that the fuel delivered to the engine from the carburetor is already in vapor form or the fuel particle size is minimized.
When the liquid fuel spray from the carbur-etor jets contacts the filtered air stream in the venturi section of the carburetor, a process of surface evaporation begins. Since heat energy is required to facilitate this process, heat is taken from the air stream and the liquid fuel particles travelling toget-~her as a mixture. In the absence of an additional source of heat energy to maintain the temperature of s~
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the mixture, the temperature consequently decreases downstream from the point where the liquid fuel spray and the air stream first come into contact. This nega-tive temperature gradient decelerates the evaporation rate of the liquid fuel particles in the air-fuel mix-ture. As a result, the size of liquid fuel particles at the point of entry into the combustion chamber will be relatively large and only a relatively small amount of the fuel will be in true vapor form.
When the air-fuel mixture in the combustion chamber of the engine is ignited, the fuel vapor within the mixture combines with oxygen from the air and com-pletes the intended combustion process. The resulting heat energy is used, firstly, to elevate the tempera-ture of the mixture back to the original air and fuel intake temperature levels, and then to a level which produces the pressure required to drive the engine piston during its work stroke. During the elevated combustion temperatures some heat is also used to fur-ther evaporate fuel particles still in liquid form.
Since the foregoing processes take placewithin a very short time span, the fuel does not have enough time to fully vaporize and fully oxidize in the engine combustion chamber -- the combusion is incom-plete. Consequently, the exhaust emits combustiblefuel together with the products of complete combustion.
Not only is the emission of combustible fuel wasteful from the point of view of fuel economy, but it also represents exhaust pollution.

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Flow turbulence is another factor which will bear upon evaporation of fuel in an air-fuel mixture.
When surface evaporation of a liquid fuel particle first begins, a molecular fuel vapor cloud, at equili-brium concentration with a surrounding layer of air,develops in the immediate neighbourhood of the parti-cle. For further evaporation of the fuel particle to take place, dissipation of the saturated fuel vapor cloud is required. In a carburetor, dissipation results from the turbulence represented by cross-flow velocity components both tangential and normal to the velocity vector of the main air-fuel mixture flow.
Such turbulence also facilitates heat energy transfer from within the air-fuel mixture flow to make further evaporation of the liquid fuel particles possible.
Thus, it will be apparent that the fuel evaporation process and consequently fuel economy may be impeded if the turbulence within the air-fuel mixture flow is insufficient to dissipate fuel vapor clouds from around the liquid fuel particles which they initially surround.
In conventional internal combustion engines, which receive fuel via a standard carburetor, the fuel combustion process is not ideal -- fuel is wasted resulting in exhaust pollution. The inventors have found that the problem, at least in part, can be traced to the fact that a significant amount of fuel leaves the carburetor still in liquid particle form and there is insufficient time for the particles to completely evaporate and combust in the engine combustion chamber - ~140821 before the chamber is exhausted. To reduce the amount of such waste and pollution, the inventors have developed a fuel saving device for connection between the carburetor and the intake manifold of the engine.
In a broad aspect of the present invention, there is provided a fuel saving device for connection between an air-fuel mixture flow output opening of a carburetor and an output opening of the intake manifold of an internal combustion engine. The device includes an input opening for receiving an air-fuel mixture flow from the output opening of the carburetor and an output opening for delivering an air-fuel mixture flow to the input opening of the intake manifold. In addition, the device includes means for maintaining the input opening of the device in flow communication with the output opening of the carburetor and means for maintaining the output opening of the device in flow communication with the input opening of the intake manifold. Conditloning means is included between the input and output openings of the device for heating and turbulating the air-fuel mixture flow received at the input opening of the device and for delivering the heated and turbulated flow to the input opening of the engine intake manifold via the output opening of the device.
The conditioning means comprises means for dividing the air-fuel mixture flow received at the input opening of the device into a plurality of separated and redirected flows and then recombining the separated and redirected flows into a single recombined flow. The dividing means includes a plurality of heat ~, . . .

1~4~)821 exchan~e tubes for carrying the separated flows, each of the tubes being nonlinearly configured so as to turn the direction of the flow within the tube between an inlet of the tube and an outlet of the tube. Further the conditioning means comprises means for heating the plurality of separated flows.
The fuel saving device is for adding both heat and turbulence to the air-fuel mixture flow from the carburetor, thereby enhancing the liquid fuel evaporation process. The separation, redirection and recombination of the air-fuel mixture flow contributes to overall turbulence. Also, improved heat transfer characteristics from a source of heat to the air-fuel mixture are permitted when the single flow is separated lS into a plurality of separated flows, each of which is turned as described above. The separation of the flow is to provide an expanded heat transfer surface area within the heat exchange tubes. The turning of the separated flows is to facilitate evaporation due to inertia forces which will act on liquid fuel particles in the flows. Around turns, such forces will separate liquid fuel particles from the flows bringing the particles into direct contact with the expanded heat transfer surface provided by the walls of the tubes, thereby facilitating improved turbulent heat transfer.
In a preferred embodiment of the present invention, the fuel saving device comprises an intake plenum having an input opening for receiving an air-fuel mixture flow from the output opening of a carburetor and a discharge plenum generally disposed ,~';`i ` -'' 114~82i below the intake plenum, the discharge plenum having an output opening for delivering an air-fuel mixture flow to the input opening of an engine intake manifold.
Means are provided for maintaining the input opening of the intake plenum in flow communication with the output opening of the carburetor. Similarly, means are provided for maintaining the output opening of the discharge plenum in flow communication with the input opening of the intake manifold. In addition, the device includes a plurality of heat exchange tubes for providing flow communication between the intake plenum and the discharge plenum, each tube having an inlet in flow communication with the inta~e plenum and an outlet in flow communication with the discharge plenum. Each inlet is for receiving outwardly from the intake plenum a portion of the air-fuel mixture flow received at the input opening of the intake plenum. Each outlet is for delivering the portion received at the corresponding inlet inwardly to the discharge plenum. Each of the tubes is nonlinearly configured to turn the direction of the separated flow within the tube between the inlet of the tube and the outlet of the tube. Further, the device includes means for heating the plurality of tubes.
As will be appreciated, the air-fuel mixture flow received at the input opening of the intake plenum is divided in the intake plenum into a plurality of separated flows, each of which flows proceeds through one of the plurality of tubes. The separated flows are then recombined in the discharge plenum. Necessarily, , 8;Z1 the air-fuel mixture flow is turned and redirected because it (in its separated portions) is first directed outwardly from the intake plenum and, subse-quently, inwardly to the discharge plenum. Turning must occur in between to have the flow first move "out"
then move "in". Further, between the "outward" and "inward" turning and redirecting, there is a necessary downward turning and redirecting because the discharge plenum is generally disposed below the the intake plenum.
As previously indicated, such separation, redirection and recombination contributes to overall turbulence. Also, improved heat transfer characteris-tics are permitted. By heating the heat exchange tubes, the separated flows flowing within the tubes are in turn heated. In effect, the walls of the tubes provide an expanded heat transfer surface, and the overall heating tends to be faster and more uniform than with a single combined flow where the centre of the flow is insulated to a greater degree by outer layers of the flow. In addition, the turning of the separated flows within the tubes enhances heat transfer because the liquid fuel particles of the flows are driven towards the walls of the tubes around the turns.
The separation, redirection and recombination referred to above may be readily achieved with the use of nonlinear tubes each having two 90 bends (viz. the form of a "C" with right angled corners). Differing shapes could be used (for example, a smooth semi-circular or semielliptical "C"), but 90 bends are 114~8Zl considered preferable because their abruptness contri-butes to turbulence.
Advantageously, the intake plenum and the discharge plenum each have a cylindrically walled con-S figuration around a common cylindrical axis extendingdownwardly through the intake plenum then downwardly through the discharge plenum. The intake plenum and the discharge plenum may be formed in an upper portion and a lower portion, respectively, of a single cylin-drical enclosure. This configuration can contribute toan overall compact structure in which each of the heat exchange tubes leads radially outwardly from the intake plenum, then downwardly, then radially inwardly to the discharge plenum, all of the tubes having substantially the same size and shape.
Various means for heating the heat exchange tubes are contemplated within the scope of the present invention. Preferably, the heating means comprises a jacket enclosing all of the tubes, the jacket having an inlet for receiving a heated flow (gaseous or liquid) and an outlet for discharging the heated flow. Advan-tageously, the heated flow may be a flow of hot coolant liquid from a cooling system of the engine. In this case, the heating means includes means for connecting the inlet of the jacket in flow communication with means for delivering hot coolant liquid from the engine cooling system and means for connecting the outlet of the jacket in flow communication with means for return-ing the hot coolant to the engine cooling system. The heated flow may be derived from other sources - for ~, ., ! `

1141)8Zl example, in the case of an air cooled engine, hot air heated by the engine may be ducted around the heat exchange tubes.
The present invention lends itself to a com-pact construction with simple and relatively few parts.
In a preferred embodiment, the intake plenum and the discharge plenum each have a cylindrically walled con-figuration around a common cylindrical axis, the intake plenum and the discharge plenum being divided by a common wall which forms on one side the bottom of the intake plenum and on the other side the top of the dis-charge plenum. The common wall could be in the nature of a flat disc but, to compensate for stresses that can develop as a result of thermal expansion, it preferably has an upward curvature.
Utilizing the present invention, significant savings in fuel economy and reduction of exhaust pollu-tion can be achieved - but without corresponding degra-dation in vehicle performance.
The foregoing and other features and advan-tages of the present invention will now be described in more detail with reference to the drawings.
Figure 1 is a cross-section side elevation view of a fuel saving device in accordance with the ~5 present invention.
Figure 2 is a top view of the fuel saving device shown in Figure 1.
Because exhaust pollution is reduced, it is considered that the present invention can substantially obviate or remove the need for catalytic converters, i:~

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the latter of which are expensive and somewhat danger-ous as a result of high temperatures and back pressures which develop during operation - not to mention the adverse effect which catalytic converters have on vehicle performance.
The fuel saving device (generally designated 30) shown in Figures 1 and 2 was developed for a 1967 Ford Falcon "Futura"~. It was a standard production model having a 200 cubic inch six-cylinder engine and an automatic transmission. Hence, as will be readily apparent to those skilled in the art, certain detailed aspects of the design now to be described tfor example, the mounting arrangement for the device) will be pecu-liar to the particular application and will require modification for different applications.
In Figure 1, a portion of a standard carbure-tor (general~y designated 10), and a portion of an engine intake manifold (generally designated 20), are both shown in broken outline. Fuel saving device 30 is connected between the air-fuel mixture flow output opening of the carburetor at 15 and the input opening of the intake manifold at 25. Carburetor 10 and engine intake manifold 20 are not shown in Figure 2.
Fuel saving device 30 includes a cylindrical intake plenum 40 having an input opening 42 for receiv-ing an air-fuel mixture flow from output opening 15 of carburetor 10. Also, the device includes a discharge plenum 50 having an output opening 52 for delivering an air-fuel mixture flow to input opening 25 of intake manifold 20.

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As can be seen in Figure 1, intake plenum 40 and discharge plenum 50 are aligned around a common cylindrical axis designated 70. The two plenums are in fact upper and lower portions respectively of a cylin-drical enclosure 75 divided by a common wall 80. Theupper surface or side ~2 of wall 80 forms the bottom of intake plenum 40, and lower surface or side 84 of the wall forms the top of discharge plenum 50. Wall 80 has an upward curvature to compensate for stresses that can develop as a result of the thermal expansion. A down-ward curvature is considered to be undesirable because liquid raw fuel could tend to pocket in the depression and be sprung upwardly into heat exchange tubes 90 (referred to next) as a result of possible springing in the wall under stress due to temperature variations.
A plurality (twelve to be precise) of heat exchange tubes 90 interconnect intake plenum 40 and discharge plenum 50 for providing flow communication therebetween. Each tube has an inlet 91 in flow com-munication with the intake plenum and an outlet 92 inflow communication with the discharge plenum. All the tubes have substantially the same size and shape, each tube leading radially outwardly from intake plenum 40, then downwardly from around a sharp elbow 93, then radially inwardly to discharge plenum 50 from around a sharp elbow 94. As can best be seen in Figure 2, the tubes are uniformly spaced circumferentially in rela-tion to common axis 70 (which shows as a point in Figure 2).

~' - ' Heat exchange tubes 90 are enclosed by a jacket 100 which has an inlet 102 for receiving a flow of hot coolant liquid and an outlet 104 for discharging the flow. The hot coolant liquid is supplied by the cooling system (not shown) of the engine of which in-take manifold 20 forms part. In the Ford vehicle referred to above, as in many vehicles, the engine cooling system includes a thermostatically controlled outer loop from the engine block through the radiator and back to the engine block, and an inner loop from the engine block through a heater (used to warm the interior air of the vehicle) and back to the engine block. A coolant pump, common to both loops for hot coolant leaving the engine block, circulates coolant through the system. Fuel saving device 30 was connect-ed in the inner loop in a parallel flow path with the the heater - coolant inlet pipe 106 leading from the inner loop on the upstream side of the heater to lnlet 102 for delivering hot coolant to the device from the engine cooling system; and coolant return pipe 108 leading from outlet 104 to the inner loop on the down-stream side of the heater for returning the coolant to the engine cooling system. In passing between inlet 102 and outlet 104, the hot coolant from the engine cooling system conveys heat to heat exchange tubes 90.
Fuel saving device 30 includes two mounting flanges 60 and 65 which were designed for compatibility with the Ford vehicle referred to above. Input opening 42 of intake plenum 40 is maintained in flow communica-tion with output opening 15 of the carburetor by .

~14~8Zl bolting the carburetor to carburetor mounting flange 60, the latter of which includes two threaded bolt holes 62 for the purpose (the corresponding bolts are not shown). A gasket 19 provides sealing for the connection. Output opening 52 is maintained in flow communication with input opening 25 of intake manifold 20 by bolting lower flange 65 of the device to the intake manifold. Two bolts 67 are used, and a gasket 29 provides sealing for the connection. Pipe 110 leading into discharge plenum 50 provides a connecting path to the "positive crankcase ventilation~ (PCV) valve thereby facilitating engine ventilation as intended by the vehicle manufacturer. Shaft 115, extending from carburetor mounting flange 60 (see Figure 2), is a mounting shaft set and aligned for compatibility with the existing carburetor control linkage of the vehicle. A temperature sensor by-pass return hole 61 for the choke control of the original carburetor has been duplicated and properly aligned in flange 60.
In the operation of fuel saving device 30, an air-fuel mixture flow from carburetor 10 flows down-wardly into intake plenum 40 where it is diverted outwardly into inlets 91 of heat exchange tubes 90.
The upwardly curved shape of surface 82 on wall 80 assists the uniform dispersion of the incoming flow to the heat exchange tubes. The resulting dispersion and change in flow direction adds desirable turbulence to the flow resulting in break-up of liquid fuel particles in the flow.

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114~)821 Within each heat exchange tube 90, further turbulence is induced by the two 90 corners which the now separated 10ws must negotiate on their way to dis-charge plenum 50. The heat exchange tubes, being heated as previously described by hot coolant from the engine cooling system, facilitate heat transfer to the air-fuel mixture flows thereby encouraging evaporation of liquid fuel particles within the flows. In this regard, it will be appreciated that the changes in flow direction within the heat exchange tubes themselves advantageously enhance the evaporation process. Iner-tia forces acting on the liquid fuel particles as they are required to negotiate the corners in the heat exchange tubes tends to develop a liquid fuel film against the hot inside walls of the heat exchange tubes. The heated film, in direct contact with the inside walls, rapidly evaporates and is carried away by and mixed into the passing air-fuel mixture flow.
Upon entry to discharge chamber 50 through outlets 92, the separated flows recombine into a single air-fuel mixture flow and undergo a further change in flow direction (viz. from horizontally inwardly to downwardly), all of which adds further turbulence.
Finally, the downwardly flowing air-fuel mixture flow is delivered via output opening 52 to input opening 25 of engine intake manifold 20 from where it is then distributed to engine combustion chambers (not shown) in the usual manner.
Using the Ford vehicle referred to above both with and without fuel saving device 30, stationary and ~.
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~14~821 road tests demonstrated that a significant improvement in fuel efficiency (and consequently less e~haust pol-lution) could be achieved with the device. Visually, a simple "white cloth" exhaust emission test verifiea a reduction in unclean emissions. In conducting the tests, substantial efforts were made to ensure that any improvement in performance could not be attributed to changes in vehicle operating characteristics, and the same test route was followed under similar traffic conditions. The vehicle was fully tuned to factory specifications prior to each test for the purpose of starting with the same initial conditions, such as air-fuel mixture ratios, timing and the like.
It is significant to bear in mind that the successful results indicated were achieved without noticeable degradation in the performance of the vehi-cle under test. No engine operating changes or short-comings such as overheating, loss of power, or loss of response were detected. -The general compactness and simplicity in construction of fuel saving device 30 is also of signi-ficance. As used on the Ford vehicle under test, cylindrical enclosure 75, having an outside diameter of 1 5/8 inches, had a length of about 3 inches - the latter of which corresponds to the overall height of the device. Jacket 100 had a vertical height of about 1 3/4 inches and an outside diameter of abut 4 1/8 inches. ~he twelve heat exchange tubes 90 all had sub-stantially the same size and shape, their outside diameter being about 3/8 inches. Coolant inlet and ; !~ `' ' , ~ . ' ' : ' ~ )8Zl coolant return pipes 106 and 108 each had an outside diameter of about 5/~ inches.
One item that did require some minor innova-tion not considered to bear upon the test results was the making of a somewhat shallower air cleaner. Not-withstanding the compactness of fuel saving device 30 as used for the tests, the height of the device plus the height of the original carburetor assembly would not permit the vehicle hood to be closed. This problem was circumvented by replacing the standard air cleaner which came with the vehicle with the shallower air cleaner. An alternate solution would have been to install a clearance Nbubble~ in the hood.
It will be appreciated by those skilled in the art that many modifications and changes within the scope of the present invention are possible. Indeed, it is to be plainly expected that at least some changes from the specific embodiment shown in the drawings will be required from time-to-time, if for no other reason but to adapt the device for different vehicles having different engine intake manifold and carburetor system geometries. However, it is also to be expected that other aspects of the design will vary for different vehicles depending upon the vehicle and the style and size of the engine and carburetion system. For fuel saving device 30, some testing was required to deter-mine the number and size of heat exchange tubes 90 which were considered to achieve an optimum or near optimum performance for the vehicle and engine and carburetion system involved. This will also be true ' ~408Zl' for different vehicles having different engine and carburetion systems. Generally speaking, the number of heat exchange tubes and their diameters will be a function of engine displacement. Their length will be a function of the coolant used. If there are too few heat exchange tubes, or if their equivalent length is too long, then the effect of the fuel saving device may be to cause unwanted throttling. If the equivalent length of the tubes is too short, then insufficient heating in the tubes may be the result. If there are too many heat exchange tubes, no additional advantage may be gained from those that are extra, or, there may be a reduction in turbulence sufficient to adversely reduce the amount of heating which can take place in the tubes.
Fuel saving device 30 shown in the drawings was made from copper with the exception of flanges 60 and 65 which were made from steel. Obviously, however, other metals having good heat transfer characteristics could be used.
Other alternatives which are contemplated include the incorporation of flanges such as flanges 60 and 65 as part of the coolant jacket and the use of Uthrough bolts" from the carburetor through the fuel saving device to the engine intake manifold. It is also considered that a fuel saving device in accordance with the present invention may be incorporated directly by casting into the lower part of a carburetor or into the upper part of an engine intake manifold.

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3Zl Further, and while the geometry and configu-ration of fuel saving device 30 is considered to embody features which are advantageous, it is to be understood that means differing from the specific means shown may be utilized for the purpose of usefully heating and turbulating an air-fuel mixture flow. As previously indicated, the invention may be implemented with air-cooled engines by ducting coolant air heated by the engine to the fuel saving device. In such a case, heat exchange tubes such as heat exchange tubes 90 may be equipped with external fins to better facilitate heat transfer between the hot air contacting the outside of the tubes and the air-fuel mixtures flowing within the tubes. Alternately, or additionally, heat transfer fins may be utilized inside the heat exchange tubes.
Various other changes and modifications will occur to those skilled in the art, and it is to be understood that the invention is not considered to be limited to the particular embodiment described above with reference to the drawings.

Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVELEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A fuel saving device for connection between an air-fuel mixture flow output opening of a carburetor and an input opening of the intake manifold of an internal combustion engine, said device comprising:
(a) an input opening for receiving an air-fuel mixture flow from the output opening of the carburetor;
(b) means for maintaining the input opening of the device in flow communication with the output open-ing of the carburetor;
(c) an output opening for delivering an air-fuel mix-ture flow to the input opening of the intake mani-fold;
(d) means for maintaining the output opening of the device in flow communication with the input open-ing of the intake manifold; and, (e) conditioning means between the input and output openings of the device for heating and turbulating the air-fuel mixture flow received at the input opening of the device and for delivering the heated and turbulated flow to the input opening of the intake manifold via the output opening of the device, said conditioning means comprising:
(i) means for dividing the air-fuel mixture flow received at the input opening of the device into a plurality of separated and redirected flows and then recombining the separated and redirected flows into a single recombined - Page 1 of Claims -flow, said dividing means including a plural-ity of heat exchange tubes for carrying said separated flows, each of said tubes being non-linearly configured so as to turn the direc-tion of flow within the tube between an inlet of the tube and an outlet of the tube; and, (ii) means for heating the plurality of separated flows.

2. A fuel saving device for connection between an air-fuel mixture flow output opening of a carburetor and an input opening of an intake manifold of an inter-nal combustion engine, said device comprising:
(a) an intake plenum having an input opening for receiving an air-fuel mixture flow from the output opening of the carburetor;
(b) means for maintaining the input opening of the in-take plenum in flow communication with the output opening of the carburetor;
(c) a discharge plenum generally disposed below said intake plenum, said discharge plenum having an output opening for delivering an air-fuel mixture flow to the input opening of the intake manifold;
(d) means for maintaining the output opening of the discharge plenum in flow communication with the input opening of the intake manifold;
(e) a plurality of heat exchange tubes for providing separated and redirected flow communication between said intake plenum and said discharge plenum, each tube having:

- Page 2 of Claims -(i) an inlet in flow communication with said in-take plenum for receiving outwardly from the intake plenum a portion of the air-fuel mix-ture flow received at the input opening of the intake plenum; and, (ii) an outlet in flow communication with said discharge plenum for delivering said portion inwardly to the discharge plenum;
(iii) each of said tubes being nonlinearly config-ured to turn the direction of the separated flow within the tube between the inlet of the tube and the outlet of the tube;
and, (f) means for heating said plurality of tubes.

3. A fuel saving device as defined in Claim 2, wherein said intake plenum and said discharge plenum each have a cyclindrically walled configuration around a common cylindrical axis.

4. A fuel saving device as defined in Claim 3, wherein each of said tubes leads radially outwardly from said intake plenum, then downwardly, then radially inwardly to said discharge plenum; all of said tubes having substantially the same size and shape.

5. A fuel saving device as defined in Claim 2, 3 or 4, wherein said means for heating said plurality of tubes comprises a jacket enclosing all of said tubes, said jacket having an inlet for receiving a heated flow and an outlet for discharging the heated flow.

- Page 3 of Claims -

6. A fuel saving device as defined in Claim 2, 3 or 4, wherein said means for heating said plurality of tubes comprises:
(a) a jacket enclosing all of said tubes, said jacket having an inlet for receiving a heated flow and an outlet for discharging the heated flow;
(b) means for connecting the inlet of the jacket in flow communication with means for delivering the heated flow as hot coolant liquid from a cooling system of the engine; and, (c) means for connecting the outlet of the jacket in flow communication with means for returning the discharged flow to the cooling system of the engine.

7. A fuel saving device as defined in Claim 3, wherein said intake plenum and said discharge plenum are formed in an upper portion and a lower portion, respectively, of a single cylindrical enclosure.

8. A fuel saving device as defined in Claim 7, wherein each of said tubes leads radially outwardly from said intake plenum, then downwardly, then radially inwardly to said discharge plenum; all of said tubes having substantially the same size and shape.

9. A fuel saving device as defined in Claim 3, 7 or 8, wherein the intake plenum and the discharge plenum have an upwardly curved common wall which forms on one side the bottom of the intake plenum and on the other side the top of the discharge plenum.

10. A fuel saving device as defined in Claim 7 or 8, wherein said means for heating said plurality of - Page 4 of Claims -tubes comprises a jacket enclosing all of said tubes, said jacket having an inlet for receiving a heated flow and an outlet for discharging the heated flow.

11. A fuel saving device as defined in Claim 7 or 8, wherein said means for heating said plurality of tubes comprises:
(a) a jacket enclosing all of said tubes, said jacket having an inlet for receiving a heated flow and an outlet for discharging the heated flow;
(b) means for connecting the inlet of the jacket in flow communication with means for delivering the heated flow as hot coolant liquid from a cooling system of the engine; and, (c) means for connecting the outlet of the jacket in flow communication with means for returning the discharged flow to the cooling system of the engine.

- Page 5 of Claims -