US 3712065 A
A system for reducing the back pressure on the exhaust valves of an internal combustion engine which includes, for instance, a source of compressed air, which may be powered by the internal combustion engine, and, in particular, a unique momentum transfer pump device which utilizes the high pressure compressed air output to create a suction or lower pressure at the exhaust manifold. A diffuser may be connected at the output end of the momentum pump to further increase the efficiency of the momentum pump.
Description (OCR text may contain errors)
United States Patent 1 Hurst ANTIPOLLUTION EXHAUST SYSTEM FOR AN INTERNAL COMBUSTION ENGINE  Inventor: Robert H. Hurst, West Barrington,
 Assignee: Clevepak Corporation, New York,
 Filed: Dec. 4, 1970  Appl. No.: 95,319
 US. Cl. ..60/274, 60/307, 60/316  Int. Cl ..Fln 3/10  Field of Search ....60/30 R, 32 R, 316, 307, 274;
 References Cited UNITED STATES PATENTS Cote /344 Ohain Barker Decker 1 Jan. 23, 1973 2,667,031 l/l954 Ryder ..60/32 R 3,082,597 3/1963 Hamblin. .....60/30 R 3,599,427 8/1971 Jones ..60/30 R FOREIGN PATENTS OR APPLICATIONS Canada ..60/ 3 17 Great Britain ..60/30 R Primary Examiner--Doug1as Hart Attorney-Cushman, Darby & Cushman  ABSTRACT A system for reducing the back pressure on the exhaust valves of an internal combustion engine which includes, for instance, a source of compressed air, which may be powered by the internal combustion engine, and, in particular, a unique momentum transfer pump device which utilizes the high pressure compressed air output to create a suction or lower pressure at the exhaust manifold. A diffuser may be connected at the output end of the momentum pump to further increase the efficiency of the momentum pump. I
20 Claims, 3 Drawing Figures ANTIPOLLUTION EXHAUST SYSTEMFOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION This invention relates to devices for increasing the operating efficiency of internal combustion engines and, more particularly, to devices which accomplish the above object by reducing the back pressure on the exhaust valves of an internal combustion engine.
Ever since the internal combustion engine was first developed, skilled artisans have sought to improve its efficiency. A multitude of methods have accordingly been developed each having peculiar advantages and disadvantages. For the purposes of this discussion it should be sufficient to" note that one important method for improving internal combustion engine efficiency comprises the reduction of back pressure on the exhaust valves of the internal combustion engine. It is well known that in four stroke otto cycle" internal combustion engines, some of the power developed'during the power stroke, is required during the exhaust stroke to force the combustion products from the cylinder out through the exhaust valve and engine exhaust system. If the back pressure can be reduced therefor, engine efficiency will be improved. The reduction of back pressure on the exhaust line also allows an advantageous change in the design of the cylinders of an internal combustion engine. When back pressure is reduced, the cylinder exhaust valves can be smaller which allows the cylinder intake valves to be larger. As is well known, larger intake valves are advantageous since they permit a greater rate of fuel-air mixture to be fed to the cylinder which in turn increases the cylinders efficiency. Alternatively, to produce the same horsepower, an engine of less size, or overall weight, could be used.
The above discussion is included herein to show the past need for a device for reducing back pressure on an internal combustion engine. Furthermore, the importance of reducing back pressures on the internal combustion engine grows as more or larger devices impeding the exhaust gas flow are placed between the engines exhaust manifold and the atmosphere.
Thus where antipollution devices are added to an automobiles exhaust system, the desirability of a back pressure reducing device is greatly increased. Of course, any means for pulling a suction on the exhaust system of an internal combustion engine and thereby reducing back pressure requires a separate input of energy. It was the major disadvantage of the equipment which could have been used in the prior art in an attempt to reduce back pressures on internal combustion engines that this equipment required relatively high energy input to achieve a significant reduction on back pressure.
It was also known by the prior art that the introduction of air into the exhaust gases could be advantageous to reducing pollution. The air could be added merely to dilute the exhaust gases or to prepare them for a subsequent anti-pollution step such as after burning or catalytic conversion. It was not known to the prior art, however, effectively to introduce this secondary air" in an inexpensive manner so as to also reduce the back pressure on the exhaust line.
SUMMARY OF THE INVENTION Thus it is an object of this invention to provide a highly efficient internal combustion exhaust system which may be used, e.g. in an automobile. More specifically, it is an object of this invention to provide a momentum pump means for creating a reduced pressure at a suitable location in the exhaust line of an internal combustion engine which is highly efficient. Also, it is the object of this invention to provide a single means for introducing secondary air to exhaust gases and reducing the back pressure on an internal combustion engine.
The above and other objects of this invention may be accomplished through the addition to the exhaust system of an internal combustion engine of a compressor unit, which may be powered by the fan belt of the internal combustion engine, for producing a desired volume of high pressure air, tubing connecting such source of high pressure air to a momentum pump, as more fully described hereafter, and means directing the high pressure air from the momentum pump into the exhaust line of an internal combustion engine. The efficiency of the momentum pump may still further be increased through the use of a diffuser at the downstream end of the pump.
The air compressor may be replaced by another suitable source of compressed air, as, for instance, by a tap into the exhaust manifold or a rechargeable tank of compressed gas.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an internal combustion engines exhaust system in accordance with applicant's invention;
FIG. 2 is a side sectional view of the momentum pump and diffuser utilized in the applicant 5 INTERNAL COMBUSTION ENGlNEs exhaust system; and
FIG. 3 shows an end view, partly in section, of the momentum pump and diffuser utilized in the internal combustion engine's exhaust system according to applicants invention.
' DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION In FIG. 1, numeral 1 indicates a conventional internal combustion engine while numeral 2 indicates a conventional exhaust manifold connected to an internal combustion engine for collecting exhaust gases from the cylinders of the internal combustion engine. Also conventional is the radiator cooling fan 3 and the fan shaft 4 which are driven by the internal combustion engine through conventional means, ndt shown in detail. An endless belt 5 is tightly wrapped around a pulley 6 which in turn is rigidly attached to the fan shaft 4. At its other end the endless belt 5 is tightly wrapped around the input shaft pulley 7 of air compressor 8 for powering air compressor when the internal combustion engine is operating.
The air compressor should be capable of developing at least about 20 p.s.i.g., and pressures up to about p.s.i.g., are presently considered to be the most useful pressure range for the compressed air source. The made-up air for the compressor 8 may be supplied from a tap in the manifold upstream of the pump, as illustrated in FIG. I, by tap 41 and line 42.
The outlet line from the air compressor with optional control valve 9 is connected by standard tubing to the entrance for the compressed air storage tank 12. The check valve 11 can be used to prevent the compressed air from seeking ambient conditions through line and the air compressor when the air compressor is not in operation.
High pressure air stored in tank 12 exits through solenoid air control valve 13 and tubing 14 to the plenum chamber 15 of the momentum pump 30. The solenoid of solenoid valve 13 may be electrically connected to the ignition circuit 16 of the internal combustion engine in such a manner that valve 13 is opened when the ignition switch is closed and vice versa. The air supplied to the plenum chamber 15 of the momentum pump, from tank 12, flows out from chamber 15 by way of jet bores 17 and 17' (best seen in FIG. 3) into the main passage of the momentum pump 30.
It is to be noted that the jet bores 17 and 17' have a very short dimension along their central axes and that their central axes make an angle in the range of 15 to 40 with respect to the central axis of passage 18 of the momentum pump. it is also noted that the downstream ends of the jet bores 17 and 17' point towards the downstream end of the momentum pump passage 18 and the high velocity air streams flowing therethrough thus impart a downstream force vector to the relatively slow moving exhaust gas stream flowing through pressure 18.
lt is further noted that a diffuser 20 may be attached to the downstream end of the momentum pump in communication with passage 18. In this case, the downstream end of diffuser 20 is connected to duct 21 which communicates with an exhaust gas treating such as the muffler or the exhaust gas purifying device 22. The output of the exhaust gas purifying device 22 is then transmitted via tailpipe 23 to the atmosphere.
The upstream end 20a of the diffuser has essentially the same internal shape and cross-sectional area as the downstream end of passage 18, but the diffuser gradually increases in internal cross-sectional area until it reaches its downstream end 20b whose cross-sectional area exceeds the upstreams cross-sectional area within the range of about 1 to 4 times. Further, the angle of the ingested gas and the diameter of the ingested gas hole determine the distance that the opposite wall is from the hole from which the gas escapes; and further, the distance from the ingested hole to where the diffuser starts. That is, laboratory experimentation has shown that for a rectangular chamber whose internal dimensions are X 1% inches and using two ingested holes, an angle of 22 with an 0.082 inch diameter hole requires a length of about 2% inches from point ofingest to the beginning point of diffuser to obtain maximum efficiency for that size pump.
The operation of the internal combustion engine exhaust system as described above will now be discussed. When the ignition switch ignition circuit 16 is closed, air solenoid valve 13 is opened and compressed air, previously stored in the storage tank 12, flows through tube 14 into plenum chamber 15 of the momentum pump. Simultaneously therewith the internal combustion engine 1 is started, and fan shaft 4 starts to rotate which, through shaft pulley 6, endless belt 5 and input shaft 7, powers the air compressor 8 which, through the output line, valve 9 and tubing 10 and check valve 11, delivers compressed air to storage tank 12.
As the internal combustion engine 1 operates, exhaust gases are produced, collected at exhaust manifold 2 and travel down the exhaust line to the passage 18 of the momentum pump. Now referring to FIG. 3, it is seen that compressed air delivered from storage tank 12 enters the plenum chamber 15, and is stabilized therein before it flows into the jet bores.
This compressed gas then exits through the short substantially circular jet bores 17 and 17' at effective sonic to supersonic velocities, entering the passage 18 still at such velocities.
The circular bores intersect the wall of passage 18, such that the exit holes of bores in the passage have a substantially elliptical shape. This shape is believe to have a contributing factor to the efficiency of the momentum pump.
On exiting from the jet bores, this high velocity air stream, vectorially directed from the device as described, creates a highly turbulent vortical flow of air. Some mixing of this air takes place with the exhaust gas due to shear between the laminar exhaust gas stream and the air jet vortices. However, the very highly efficient transfer of the momentum from the high velocity airstream to the relatively slow moving exhaust gases in passage 18 is believed to largely take place by a more mechanical, screw-conveyor-like, action of the air jet vortices carrying the exhaust gas stream forward along the vector axis of said jets. Studies indicate that the exiting high velocity airstream from each jet establishes a pair of counter-vortical flow paths indicated by the numbers 24, in FIG. 3. These high velocity vortical flows spin the pumped exhaust gases into something resembling rigid body rotation as shown in FIG. 3 by a sheering action. Once rotating, the exhaust gas will retain this available angular momentum without suffering significant additional shear and associated viscous dissipation and thus the momentum pump reflects an attractive efficiency of operation. In effect, the momentum pump utilized in this invention constitutes, a means to transfer momentum from a relatively low volume flow of high speed gas to a large volume of relatively low speed gas, with the result that the velocity of the latter is greatly increased with remarkably high efficiencies as compared to conventional venturi tune devices.
Since the jet bores are angled as described above, air introduced into the passage 18 has a vector of force pointing downstream in the axial direction. Thus, the turbulent mixture of compressed air and exhaust gases is driven by the axial component of the compressed air input force towards the downstream end of the momentum pump. Viewed in three dimensions the jet bores create helical vortices which greatly improve the mixing and momentum transfer between the compressed air and exhaust gas streams. While the vortical flow path might provide a smaller vector force component in the desired downstream direction than in laminar flow, the effect from the vigorous mixing which thus occurs is advantageous.
At the downstream end 20a of the passage 18 a diffuser may also be placed to further improve the momentum pump's efficiency. Diffusers are normally used in subsonic fluid flow systems to reduce the velocity and increase the static pressure of a fluid passing therethrough. Thus it would seen contrary to the purpose of this invention to add a diffuser to the downstream end of a pump whose purpose is to reduce pressure by causing high velocity gas flow. Nevertheless, the addition of the diffuser to a momentum pump as described above mayv result in a still further increase of at least about 25 percent in the pump's efficiency. This unexpected result, i.e., this increase in efficiency, appears to derive from the conversion of energy from the spinning tangentially directed energy of the air jet vortices, to a spinning axial directed energy. Basically the input jet of air imparts a violent tangential spin to the lamina flow of exhaust gases with the resulting storing of angular kinetic energy. The diffuser, by gradually expanding or opening up the cross sectional area, converts the stored kinetic energy, both tangential and axial, to the pressure energy, which is in a downstream direction, thereby increasing the efi'iciency of this pump.
It will be appreciated that by thus accelerating the velocity of the exhaust gases on the exhaust line, the back pressure normally existing upstream at the exhaust parts or exhaust manifold of the engine is greatly reduced. Even though the flow volume of air introduced in the exhaust gas line is generally only a minor fraction of the flow volume of the exhaust gases treated, e.g., generally only about to about 50percent, preferably no more than percent, these beneficial effects are achieved. Where a diffuser is used, the outputtherefrom is connected by conduit 21 to exhaust gas purifying device 22 and therefrom by tailpipe 23, to the atmosphere.
A presently preferred mode of operation of the automobile exhaust system in accord with applicants invention has been described above. It should be, however, obvious to one skilled in the automotive art that many modifications are possible within the basic scope of this invention. Thus instead of an air compressor, a turbine unit such as would be used in a supercharger device could be utilized instead for the supply of compressed air to the supply chamber 15 of the momentum pump.
While the air compressor is shown to be powered from the fan shaft, it could also be powered by other means associated with the internal combustion engine such as an electric motor energized by the engines generator or by means not associated with the engine. in addition, the compressed air storage tank 12 and its associated valves and circuitry could be dispensed with and the output of the air compressing means connected directly to the supply chamber 15 of the momentum pump. In this event, of course, during start-up conditions an under-pressure flow of compressed gas would be received in supply chamber l5and thus the momentum pump would not be operating as efficiently. This modification would have the advantage, in some cases however, of an automatic correlation between the flow rates of the air delivered to the air supply chamber 15 and the exhaust gases delivered to the passage 18 of the momentum pump.
Although the momentum pump is shown in the drawings and described above as located between the exhaust manifold and the purifying device, it may also be located downstream from the purifying device or muffler. Alternative locations include those adjacent the exhaust manifold. A plurality of such devices could be placed on each cylinder's exhaust line leading to the manifold itself, or one such pump may be placed upstream of the purifying device, and a second pump may be placed downstream of that device. In each instance, the operation will be essentially as described above.
Also, a standard muffler could be utilized in addition to or in place of the exhaust gas purifying device described above.
Einally, while the momentum pump is shown with two short bores, a momentum pump utilizing only one such bore or having more than two such bores may also be used. In these variations the shape of the passage 18 for greatest efficiency may be established by suitable configuration tests measuring pressure reductions. The use of at least two such bores with a passage 18 of substantially rectangular cross-section as shown is presently indicated as providing a more efficient pumping action than a single bore design. The applicants tests have also indicated that where it is desirable to increase the passage size in the momentum pump without reducing pumping efficiency, the relative height of the passage should be maintained essentially as it is shown while the width of the passage should be increased in increments which are about one-half as wide as the passage shown and an additional bore, sized and angled as are the two bores shown, is positioned at the median line of each such additional width increment.
Passages 18 which are not substantially rectangular are also within the scope of applicants invention; for instance, the passage may be a circle (especially with single jet bore pumps), a hexagon or any other regular or irregular cross-sectional shape. The important criterion for best results in a specific device is to suitably space the jet bores from each other such that maximum vortical action achieved (which means, in most cases, such that minimal vortical interferences and self-destroying energy losses are achieved). ln some instances, as with three jet bores, one of the bores may be located at a position more upstream or downstream than the other two jet bores. Of course, as the number of bores increases, the size of the plenum chamber (the internal shape of which is not critical) changes so that an adequate source of stabilized air is available to all the bores. It is important, in any embodiment, that the jet bore have minimum length.
While the momentum producing fluid has been described above as air, it is also possible that the introduction of a gas other than air to the exhaust gases would be desirable. For example, ammonia is added to exhaust gas in one exhaust gas purifying process.
Where it is desired to add a gas other than air, the air compressor 8 and storage tank 12 can be replaced with a tank of the compressed compress gas.
It will be appreciated from the foregoing description that the capacity of the compressed air supply source must be sufficient to maintain the plenum chamber at the required pressure conditions. Further, said plenum chamber should be sufficiently large so as not to be depleted of such pressurized air during operation of the momentum pump. Further, the jet bores should be small enough that the pressurized gas issuing therefrom will exit at at least substantially super-sonic velocities, while the jet gas stream should have sufficient volume passing through said jet bores such that the stream in the passage is accelerated to the desired velocity, i.e., that the jet gas stream has sufficient mass as well as sufficient velocity to produce the desired momentum.
In any given embodiment of the invention it will be apparent that the sizing of these various components (e.g., the compressed gas supply source, the plenum chamber, and the jet bores, as well as the passage) will be selected according to the back pressure reduction desired.
In general, the jet bores will have a length which is at most about from one-half to 2 diameters of said bore for most efficient operation. The practical limit on the length of the said bores is dictated by the requirement for sufficient surrounding wall thickness to define said bore and said passage.
Further, the exit opening of the jet bore should be essentially flush with the adjacent wall of the passage way for it is through this structure that the momentum pump which is especially believed to contribute to the higher efficient transfer of energy from the high velocity jet gas stream to the relatively low velocity exhaust gas flow.
What is claimed is:
1. In an internal combustion engine exhaust system having an exhaust line surrounded by a wall for conveying exhaust gases from said engine to the surrounding atmosphere, the improvement comprising an apparatus for reducing the back pressure of said exhaust gases in said exhaust line comprising:
means for producing a supply of compressed gas,
a plenum chamber located adjacent said exhaust line,
means for delivering said compressed gas to said plenum chamber,
jet bore means located between said exhaust line and plenum chamber said bore means permitting egress of at least one jet of said compressed gas from said plenum chamber into said exhaust line including at least one circular bore which creates an elliptically shaped aperture at its intersection with said wall which is flush with said wall to create turbulence downstream of said bore in said exhaust line,
at a vector angle with respect to the principal direction of flow of said exhaust gases of between about 10 and 40, and at least above sonic velocities, and at a required flow volume of about percent to about 50 percent of the flow volume rate of said exhaust gases,
thereby creating for each jet a pair of highly turbulent counter vortices which effect mixing of said compressed gas jet with said exhaust gases so that the vector momentum of said jet is transferred to said exhaust gases to accelerate the velocity thereof through said exhaust line, whereby the back pressure of said exhaust gas flow is substantially reduced and the exhaust gases are effectively mixed with the gas jet.
2. The apparatus as recited in claim 1 wherein said means for producing a supply of gas includes an air compressor driven by said internal combustion engine.
3. The apparatus as recited in claim I wherein said means for producing a supply of gas includes a tank of compressed gas.
4. The apparatus as recited in claim 1 further including means located between said supplyof compressed gas and said plenum chamber for controlling the pressure of gas supplied to said plenum chamber.
5. The apparatus as recited in claim 1 further including flow directing means located downstream of the intersection of said exhaust line and said jet bore means for smoothing the turbulence induced in said exhaust gases and thereby increasing the efficiency of said apparatus.
6. The internal combustion engine exhaust system as claimed in claim 5 wherein said flow directing means comprises a diffuser which has a downstream cross section larger than its upstream cross section.
7. An anti-pollution exhaust system for an internal combustion engine which has an exhaust line surrounded by a wall for removing exhaust gases therefrom to the surrounding atmosphere comprising:
means for producing a supply of compressed gas,
at least one passage located in fluid connection with said exhaust line,
a plenum chamber located adjacent said each passage,
means for delivering said compressed gas to said plenum chamber, jet bore means located between said passage and said plenum chamber said bore means permitting egress of at least one jet of said compressed gas from said plenum chamber into said passage at an angle between about 10 and 40 with respect to the principal direction of flow of said exhaust gases, at sonic or greater velocity, and at a volumetric flow rate not to exceed about 50 percent of the volumetric flow rate of said exhaust gases,
thereby creating for each jet a pair of highly turbulent counter vortices which effect flow of said compressed gas jet so that the vector momentum of said jet is transferred to said exhaust gases to accelerate the axial velocity of the latter through said exhaust line, whereby the back pressure of said exhaust gas flow is substantially reduced.
8. The anti-pollution system as recited in claim 7 wherein said passage has a rectangular cross section.
9. The anti-pollution system as recited in claim 8 wherein there are plural jet bores all intersecting the same longer side of said rectangular passage, said bores being spaced apart sufficiently so that the counter vortical flows created in said passage by their jets do not substantially interfere with one another.
10. The anti-pollution system as recited in claim 7 wherein said passage is circular in cross section and there is a single jet bore whose axis is aligned with the median line of said cross section.
11. The anti-pollution system as recited in claim 7 wherein said exhaust system includes an exhaust gas treating device, an exhaust manifold and means defining a single passage located between the exhaust manifold of said internal combustion engine and the exhaust gas treating device thereof.
12. The anti-pollution system as recited in claim 7 wherein said exhaust system includes an exhaust manifold and means defining a single passage located between the exhaust gas treating device of said internal combustion engine and the atmosphere.
'13. The anti-pollution system as recited in claim 7 wherein said exhaust system includes an exhaust gas treating device and means defining plural passages, with at least one passage located on each side of said exhaust gas treating device.
14. A process for reducing the back pressure action upon an internal combustion engine having an exhaust line, with an axis, including the steps of:
a. providing a source of gas under pressure, and
b. injecting a volume of said gas at a velocity above sonic velocity into the exhaust line at such an angle with respect to the axis of said exhaust line that momentum is transferred from said gas to the exhaust gases within said exhaust line in the downstream direction with respect to said exhaust gases.
15. The process as recited in claim 14 wherein the .16. The process as recited in claim 14 wherein the angle which said gas makes with respect to the axis of said exhaust line is in the range of l0 to 40.
17. The process of claim 14 wherein said engine has a manifold and said source of gas is derived from the manifold of said internal combustion and supplied at about the elevated pressures and temperatures normally existing in said manifold.
18. The process of claim 17 wherein ambient air is supplied to said compressor along with said gas from said manifold.
19. A method as in claim 14 wherein said step of injecting includes the step of creating a pair of counter helical vortices by injecting a jet of said gas.
20. A method as in claim 14 wherein said step of injecting a jet of air into said exhaust line via an elliptically shaped aperature formed flush with the wall of said exhaust line to create a pair of counter helical vortices.