US 3172251 A
Abstract available in
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Description (OCR text may contain errors)
,March 9, 1965 L. 1.. JOHNSON 3,172,251
I AFTERBURNER SYSTEM Filed Jan. 14, 1963 3 Sheets-Sheet 1 FIG. I
INVENTOR. LEMOINE L. JOHNSON ATTORNEYS AIR CLEANER March 9, 1965 L. JOHNSON 3,172,251
AFTERBURNER sys'rsm Filed Jan. 14, 1963 S Sheets-Sheet 2 INVENTOR. LEMOINE L. JOHNSON :0 BY F AT TORN EYS Mar 9, 96 L. JOHNSON 3,172,251
AFTERBURNER SYSTEM Filed Jan. 14, 1963 s Sheets-Sheet 5 ATTORNEYS United States Patent 3,172,251 AFTERBURNER SYSTEM Lemoine L. Johnson, St. Paul, Minn., assignor to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed Jan. 14, 1963, Ser. No. 251,162 5 Claims. (Cl. 60-29) This invention relates to an improved exhaust afterburner system incorporating a novel regenerative afterburner for use with internal combustion engines and more particularly to a system for the incineration of exhaust gases employing said novel regenerative afterburner.
The exhaust gases from the operation of internal combustion engines are known to contain products of incomplete combusition of fuel such as carbon monoxide and hydrocarbons. The total amount of hydrocarbons present may be as much as 1.2% by volume (12,000 parts per million) or more of the exhaust gases. The carbon monoxide concentration present in exhaust gases from internal combustion engines may Vary in amounts from a fraction of a percent (by volume) to by volume or even more, the average concentration at idle conditions usually being between 6.0% and 6.5%. The desirability of somehow destroying the noxious character of exhaust gases has been accentuated more recently by the recognition of the hazards to health engendered by the noxious products, particularly the hydrocarbon fraction which is responsible, at least under certain conditions, for the unpleasant atmospheric condition known as smog. While carbon monoxide is odorless, it is perniciously toxic. It is therefore apparent that the exhaust gases from internal combustion engines are a form of atmospheric contamination and should be eliminated if possible or at least brought to a minimum value, particularly in the larger cities.
While the art is replete with devices for this purpose, none appear yet to have achieved acceptance by the public or by automotive engineers. It is considered that the prior devices have failed due to factors such as the complicated nature of the devices, short life of the units, lack of operation under certain driving conditions, or ineffective reduction of the noxious character of exhaust gases to a permissive minimum value.
The use of fuel containing tetraethyl lead expels lead compounds in the exhaust gases which are particularly troublesome as respects catalytic oxidation since these gases damage catalytic afterburners, either by the accumulation of dust or, if excessive elevated temperatures exist for a short time, by glazing the catalytic surfaces. Known catalytic afterburners have not exhibited a sufficient life span for acceptance by the public. Other known types of afterburner units have failed to meet the required standdards since they fail to be effective under the varied conditions existing for exhaust gases under normal driving conditions. Additionally, the prior systems fail to be eflicient on several types of automobiles, each of which provides a varying exhaust gas condition. Some of the conditions for automobile exhaust are: a wide variation in flow rate as operation is altered between idle, deceleration, acceleration, and cruise; varied concentration of the hydrocarbons under the various driving conditions (usually highest during deceleration, a period of slow flow rate); and variations in the inlet temperature of the exhaust gases into the system. Since exhaust gases may vary in volume from about 5 to 300 standard cubic feet per minute under ordinary driving conditions, it is evident that the afterburner system must be such that is can effectively minimize the noxious character of the exhaust gases during normal driving conditions. The standard cubic foot is employed to measure the flowv rates and 3,172,251 Patented Mar. 9, 1965 ice designates a volume of gas measured at 70 F. and 1 atmosphere of pressure.
Other factors compound the problem of providing an afterburner system which is acceptable for use as an accessory for automobiles. There are very definite practical limitations as to what can befitted onto an automotive vehicle. Considerations of accessibility for replacement of parts, as well as considerations of size and shape go far in determining the utility of such devices. Since it is common practice to provide exhaust pipes which follow the bottom of the automobile and pass between various bracing members, the space available for an exhaust afterburner unit on a standard automobile is about that occupied by a conventional muffler, and should probably not greatly exceed the dimensions and proportions of a muflier. Another factor to consider is that, due to placement of the atterburner beneath the automotive vehicle, the afterburner elements may be subject to large amounts of air passing therearound. Such in turn tends to effect temperature variations in the afterburner system. Further, the system is subjected to road dust, water, and salt accumulations in certain areas which might tend vto corrode and freeze any exposed moving parts of the system and render them inoperative.
It is an object of the present invention to provide an exhaust incinerator or afterburner system wherein exhaust gases can be substantially burned to non-toxic and innocuous products.
A further object is to provide an afterburner system for internal combustion engines which will be operative under normal driving conditions by controlling the con centration of combustibles effecting the efliciency of such devices.
A further object of the present invention is to provide an exhaust afterburner system which will burn the combustible products of the exhaust gases without requiring expert manual control or technical adjustment of the average automobile to make the system operative.
The most effective way of disposing of the undesirable exhaust products of the type described is by combustion or incineration, and it is a further object of the present invention to provide a regenerative afterburner unit which is etncient in design features afiecting heat loss, size, pro-' tection of the several elements and high temperature corrosion.
These and other objects will become more apparent as this description proceeds, when read in conjunction with the description of the accompanying drawings, where- FIGURE 1 is a semi-schematic view of the afterburner system made in accordance with the present invention;
FIGURE 1a is a schematic view of a modified form of the afterburner system made in accordance with the present invention;
FIGURE 2 is a perspective view of the regenerative afterburner used in the system with the several parts shown in disassembled relation;
FIGURE 3 is a vertical sectional view taken approximately along the line 33 of FIGURE 2 with the parts in assembled relation;
FIGURE 4 is a vertical sectional view taken along the line 4-4 of FIGURE 2 with the parts in disassembled relation; and
FIGURE 5 is a perspective view of a fluid motor and locking device used in the system of the present invention.
In the following description the term vacuum as used throughout refers to a sub-atmospheric pressure condition of the nature developed in an intake manifold of an internal combustion engine.
Referring now to the drawing and particularly to FIG- URE 1 thereof, the novelsystem for the incineration of the combustible portions of exhaust gases is shown in a semi-schematic manner connected to an internal combustion engine. Only a portion of the engine is shown including the intake manifold 6, the exhaust manifold 7, a carburetor 8 and the air cleaner 9. The exhaust manifold is connected by means of an exhaust discharge tube 10 to a flow control valve 11 fixed in one end of the novel regenerative afterburner 12.
The after-burner 12, to be described hereinafter in greater detail, comprises a combustion chamber 13 and a pair .of heat-exchangers 14 and 15, positioned in linearly aligned relation with respect to said combustion chamber 13. A casing 16 encloses the combustion chamber 13 and the heat exchangers 14 and 15, and is formed with a series of passages connecting the combustion chamber and heat exchangers with the valve 11 and connecting said valve with a tail pipe or outlet tube 17.
An igniter in the form of a spark plug 18 is secured in the casing 16 and projects into the combustion chamber 13 to ignite the combustible portion of the exhaust gases. The spark plug 18 is connected by means of an electrical conductor 19 to a step-up coil 20. The coil 20 in turn is grounded in a conventional manner and is connected by suitable electrical conductors through a set of breaker points 21 to a source of electrical energy 22. On an automotive vehicle this source 22 may be the battery of said vehicle.
Means is provided for controlling the concentration of combustible substances in the exhaust gas to maintain the operation of the afterburner 12 during periods of operation when the concentration of combustibles is normally low. This means is responsive to changes in temperature within the combustion chamber 13 and includes, in the system illustrated in FIGURE 1, a conduit 23 connected to the discharge tube 10 and to one side of a valve '24. The valve 24 is connected at the discharge side to the air cleaner by means of a conduit 25. The conduits 23 and 25 and the valve 24- form a recirculation system which allows a quantity of the exhaust gas to be circulated through the engine affording a mixture in said engine having a higher'fuel to combustible air ratio than normal which will result in an increase in the concentration of combustible substances present in the exhaust discharge. This control system maintains a minimum concentration of combustibles of 2% which is necessary to sustain combustion of the exhaust gas.
An alternative arrangement for enrichment of the combustible substances in the exhaust gases is shown schematically in FIGURE la, to be described in greater detail hereinafter.
Supplemental air or air for combustion is added to the exhaust gases in the discharge tube 10 upstream of the flow control valve 11. This supplemental air is forced into the discharge tube 10 by means of a rotary sliding vane pump 26 and a conduit 27 joined to said pump and said discharge tube 10. On an automotive vehicle the pump 26 may be driven by a suitable belt from the crank shaft pulley (not shown) or by any other suitable means.
Theflow control valve 11 for the afterburner 12 is provided with a movable baifle or valve rotor 28 which is rotatable therein to periodically reverse the direction of the exhaust'gas flow through the heatexchangers 14 and 15. Suitable power means are provided to rotate the rotor 28 at predeterminedintervalsto cause the periodic reversal of .gaseous flow. In the system illustrated this power means takes the form of a fluid operated oscillating vane type motor 29 connected to a shaft 30 by which the rotor 28 is swung from one position .to another alternately connecting the heat exchangers directly with the exhaust discharge tube It) to provide a noise free valve control. The fluid pressure for the operation of the motor 29, which is of the type commonly employed to operate windshield wipers, is provided by the intake manifold 6 and pressurized air from rotary pump 26. A vacuum line 31 communicating with the intake manifold 6 is formed with a pair of branch lines 32 and 33 which communicate with the chamber of a sliding plunger type valve 34. A pressure line 35 is connected to the discharge side of the pump 26 and has a pair of branch lines 36 and 37 which also communicate with the chamber of the valve 34. The plunger of the valve 34 is operated by a cam 38 against the bias of a spring in said valve 34. The cam 38 is fixed to a suitable shaft driven by a constant speed electrical motor 39. The valve 34 serves to alternately place vacuum and fluid under pressure in fluid line 461, and the reverse condition alternatingly in line 41. Therefore, upon operation of the plunger in the valve 34 by the cam 38, fluid motor 29 is activated to cause rotor 28 in the reversing valve 11 to be moved back and forth between the solid line position thereof shown in FIGURE 1 and the dot and dash line position, at predetermined intervals, generally every 3 to 5 seconds.
A temperature responsive control valve or temperature sensing device 42 is mounted on the casing 16 of the afterburner 12 and has the probe 43 thereof extending into the combustion chamber 13 of said afterburner. The temperature sensor 42 controls the operation of the diaphragm motor 44 to operate the valve 24 in the recirculating system. The temperature sensor 42 also provides means responsive to a predetermined change in temperature within the combustion chamber 13 for interrupting the operation of the power motor 29. To this end it is associated with means for locking the rotor 28 of the flow control valve 11 in a position intermediate the two positions shown, such that the exhaust gases are allowed to flow around said baffle and directly out the outlet tube 17, and by-pass the combustion chamber when conditions of excessive temperature necessitate such by-passing, thereby controlling the temperature within said chamber and protecting the unit.
The probe 43 of the temperature sensor 42 is formed in a customary manner with materials having different coeflicients of thermal expansion which serve to operate a pair of valves (not shown) in said temperature sensor. The valves are adjustable to be opened or closed at preselected temperature conditions. The inlet side of the valves of the sensor 42 are connected to a vacuum line 46 leading from the intake manifold 6. The outlet side of one of the valves of the sensor 42 is connected to a vacuum line 47 leading from said valve to the fluid operated diaphragm motor 44 operating the valve 24. The line 47 is vented to the atmosphere when the valve of the sensor 42 is closed. During operation of the present system the sensor 42 is adjusted such that the valve will open the line 47 to the motor 44 opening the valve 24 when the temperature in the combustion chamber drops below a temperature of about 1,800 F. This allows recirculation of a portion of the exhaust gases for enrichment of the combustibles in said exhaust gases as explained above.
The outlet side of the other valve in the temperature sensor 42 is connected to a vacuum line 48 leading from said valve to a power operated locking device, generally designated 49, forming a part of the power motor 29 and will be explained in greater detail hereinafter. The valve in the sensor 42 vents the line 48 when the valve is closed, and in open position subjects the line 48 and locking device 49 to vacuum from the intake manifold 6.
The afterburner unit 12 which is the heart of this incineration system comprises several elements as shown in FIGURE 2. These several elements include the main body portion of the casing 16, a pair of perforated distribution plates 51 and 52, the heat exchangers 14 and 15, a pair of hollow tubular assemblies 53 and 54, and a cover plate 55. The casing 16 for the afterburner 12 is fabricated from a suitable material such as aluminized steel, a s'ufiiciently heavy gauge stainless steel or other suitable material which will avoid excessive corrosion. The casing 16 has a generally elliptical shape in transverse section and is similar in overall shape to that of an ordinary muffier. The casing 16 is formed with an inner chamber which is rectangular-shaped in plan and has a truncated elliptical shape in transverse section. This chamber is formed by a pair of longitudinally extending transversely spaced parallel panels 56 and 57 and a pair of transversely extending panels 58 and 59 which form the end walls of said chamber and a bowed panel 60 forming the bottom of said chamber, as illustrated in FIGURES 3 and 4 of the drawing. The outer shell 61 of the casing 16 may be formed from a single stamped and shaped piece of material formed to provide a pair of arcuate side portions 62 and 63. The arcuate side portion 62 forms a passage 64 which extends substantially the length of said afterburner unit betwen said portion and the panel 56. The passage 64 communicates with the inner chamber through an opening 65 formed in the longitudinal panel 56, adjacent one end thereof, and communicates at its opposite end with the flow control valve 11 through an opening 66 formed adjacent the opposite end of said panel 56. The arcuate side portion 63 is joined to the panel 57 and forms at one end thereof a passage 67, which communicates with the inner chamber through an opening 68 formed in said panel (FIG- URE 1), formed also in said panel 57 in aligned transverse relation with the opening 66. A wall member 70 (see FIGURE 1) is placed in the arcuate portion 63 to form one end of the passage 6'7 as illustrated in FIG- URE 1. The arcuate side portion 63 is also formed with a planar central portion 71, see FIGURES 1, 2 and 3, placed in juxtaposed relation to the panel 57. This planar portion 71 and the panel 57 are formed with openings 72 and 73 therethrough in which the spark plug 18 and the temperature sensor 42 are mounted. The remaining extent of the arcuate side portion 63, adjacent one end of the afterburner 12, forms a passage 74 and is shaped to form a circular discharge tube 75 adapted to suitably connect with the outlet tube 17. The passage 74 communicates with the flow control valve 11 and a substantial portion of said passage extends the length of the afiterburner unit beneath the panel 60 forming the bottom for the inner chamber due to the spaced relation between the shell 61 and said panel 60. As shown in FIGURE 4, one end portion of the panel 57 is of reduced width to allow communication between the portion of the passage 74 beneath the panel 60 with that portion of the passage formed by the end portion 63. At the end of the passage adjacent the flow control valve 11 a panel 76 is positioned within the shell 61 in spaced parallel relation to the end panel 58 and is formed with an opening 77 allowing passage of the incinerated exhaust gas from said valve into the passage 74 and out through the circular discharge tube 75.
The perforated distribution plates 50 and 51 are shaped to fit within the inner chamber in a position spaced from the end panels 58 and 59 and parallel thereto. These plates 51 and 52 are formed with borders or integral frame members 51a and 52a, which serve to position the plates 51 and 52 in parallel spaced relation with respect to one face of the associated heat exchangers 14 and 15. The space provided between the plate 51 and the end panel 58, and the space provided between the plate 52 and the end panel 59 form plenum areas adjacent each end of the inner chamber.
The heat exchangers 14 and 15 are similar in shape and design and are formed with an inner core 78 of corrugated ceramic affording a substantial number of parallel ordered passageways therethrough to provide a heat exchanger having a high surface to mass ratio, with a more dense ceramic matrix 79 formed therewith providing a heat exchange element of good structural design. The corrugated ceramic center portion 73 is conveniently made in accordance with the teachings disclosed in the copending application for United States Letters Patent of James R. Johnson, Serial No. 26,372, filed May 2,
1960, assigned to the assignee of this application. The corrugated inner portion of the heat exchangers 14 and 15 have high heat capacity and provide for passage of the exhaust gases therethrough. Metal clips 80 are formed to encircle the ceramic matrix 79 on each heat exchanger 14 and 15, and serve to further strengthen the structural design of said heat exchangers.
The combustion chamber 13 for the afterburner 12 is formed by the tubular members 53 and 54. The members 53 and 54 are formed by metallic clips 81 and 82, which are similar to the clips 80, each of which serves to retain four wall members 83, 84, 85 and 86, in assembled relation. The wall members 83, 84, 85 and 86 are formed with mating beveled edges and are fabricated of a refractory material such as ceramic which will withstand high temperatures. Generally a gasket or strip of heat resistant material is placed between the beveled edges of the members 83, 84, 85 and 36 to avoid attrition due to mechanical vibration or thermal expansion and contraction which would damage said members.
When the elements are positioned within the inner chamber of the afterburner 12, the two tubular members 53 and 54 form the combustion chamber 13 in a substantially centered position within said inner chamber and the heat exchangers 14 and 15 are positioned at either end of the combustion chamber in abutting relation to the tubular members 53 and 54, such that one face of each of said heat exchangers form end walls for said combustion chamber. The opposite faces of said heat exchangers 14 and 15 abut the frames 51a and 52a of the perforated distribution plates 51 and 52, placing the perforated portions thereof in spaced relation from the adjacent face of the heat exchange unit. The frames 51a and 52a are suitably fixed in position within the chamber by welding or other suitable means to prevent movement of the elements within the chamber. The cover plate 55 is then fitted within the wall panels 56, 57, 58 and 59, enclosing the chamber and the elements therein. Said cover plate 55 is secured to the side panels forming the chamber by suitable means such as metal screws or spot welding. The cover 55 is shown in position in FIGURE 3, with the elements positioned within the chamber.
The flow control valve 11, shown in FIGURE 1, has the main body portion thereof formed of mild steel or other suitable material, and the rotor 28 is mounted on the shaft 34) which is rotatably mounted in a pair of cover plates enclosing opposite ends of the chamber in which said rotor is positioned. Borings are formed through the side walls of the main body of the valve 11 and threadably receive three nipples 69a, 77a and 6611, the opposite ends of which are suitably secured to the corresponding panels 57, 76 and 56, around the openings 69, 77 and 66. These nipples 69a, 77a and 66a connect the circular chamber of the valve 11 with the respective passages 67, 74 and 64. The other boring receives the exhaust discharge tube lit and provides the inlet into the valve 11.
The shaft 39 of the valve rotor 28 preferably extends upwardly through the upper plate of the valve 11 and is suitably connected to a shaft 91 of the fluid motor 29. The motor 29 is shown in disassembled relation in FIG- URE 5 and is suitably mounted above the valve 11 to move the rotor 28 through an angle of as aforementioned upon the sequential operation of the plunger valve 34-.
The motor 29 comprises a main body portion 92, having a right-circular semicylindrical configuration, and an enclosure plate 93 formed to enclose said main body portion. The body portion 92 is formed essentially of a lower semicircular end plate 94, an upper plate and the arcuate wall member 96. The enclosure plate 93 is provided with a semicylindrical central portion 97. A vane 98 is fixed to the shaft 91 and is positioned within the main body portion 92 and the semicylindrical portion 97 of the enclosure plate 93. The shaft 91 is journaled in upper and lower semicircular end plates 94 and 95 of the main body portion 92 and the end plates of the semicylindrical portion 97, permitting oscillation of the vane 98 within said main body portion 92 and rotation of shaft 91 to transfer rotational movement to the rotor 2-8. Stop members 5 9 and 1th? are fixed to opposite sides of the vane 9-8, limiting the oscillation thereof to 90 as said stops abut the enclosure plate 93. Inlet and exhaust parts or fittings 181 and 102 are secured over openings in the enclosure plate 93 and are adapted to receive one end of the fluid pressure lines 49 and 41 leading from the valve 34.
Above the upper semicircular end plate 95 is the vacuum operated locking device 4-9 which functions as a safety device together with the rotor 28 for the afterburner 12. This locking device 49 is operative to stop rotation of the shaft 91 and to lock the rotor 28 in a position affording a by-pass for the combustion chamber 13. As shown in the drawing the shaft 91 extends upwardly above the end plate 95 and has a portion of the free end cut away leaving a semicircular projection 91a. This free end projects into an enclosed chamber formed by a pair of side walls 1&3 and 1%, an end wall 1115, an extended portion of the semicylindrical portion 97 of the enclosure plate 93, and a top plate 1196. Extending transversely through the chamber is a fulcrum plate 167 having a height less than that of the end wall 165. A locking plate 111% is positioned within the chamber and has a general configuration corresponding to that of said chamber. The plate 103 is formed with a semicircular opening 199 adapted to receive therein the projection 91a of the shaft 91. The plate 1% rests on the upper surface of the fulcrum plate 107 and is held in above the projection 91a in its normal position by a helical spring 116 fitted around the upper end of shaft 91. A flexible diaphragm 111 is placed between the to plate 106 and the flanges shown on the side walls 103 and 104 and on the end wall 195 and cylindrical portion 7. An opening is provided in the side wall 103 communicating with the vacuum line 48 for the operation of the flexible diaphragm 111.
During operation when vacuum is placed in the line 48, the flexible diaphragm draws the locking plate 108 downward against the bias of the spring 110. As the vane 98 of the motor 29 rotates to a centered position the plate 108 is forced downward and projection 91a is received in the opening 109 preventing further rotation of the shaft 91. When the vacuum in line 48 is shut off by the second valve in the temperature sensor 42, the line 48 is vented to the atmosphere by said valve and the spring 110 forces the locking plate 108 upward freeing the shaft 91. Since this by-pass is effected by a valve in the system which is frequently actuated during normal operation instead of by an independent valve positioned in the system, the danger of the valve freezing by corrosion is eliminated and an operative safety device is always present.
Referring now to FIGURE 1a, wherein the several like parts are identified by the subscript (a), the illustrated means for enriching the concentration of combustibles comprises means for preventing the movement of the carburetor choke plate to a vertical position or for moving the plate from a vertical position to a position partially closing the same. The normal automatic choke overrides the control means shown during conditions of cold engine temperature. In the construction shown, a radially extending arm 112 is journ aled to a shaft 13 which carries the butterfly choke valve or plate mounted within the carburetor 8a. The arm 112 is pivotally connected at one end to a connecting rod 45a of a diaphragm motor 44a and is formed with suitable abutment means adjacent the shaft 113 engageable with abutment means formed on said shaft such that operation of said motor by vacuum in line 47a will swing the arm 112 to a position holding the choke plate partially closed. The motor 4411 will move the choke plate about 15 from its normal, warm, operating vertical position when the motor 44a is actuated, thus increasing the fuel to air ratio within the engine, resulting in an increased concentration of combustibles in the ex- 8 haust gas. In other respects the system takes the form shown and described in FIGURE 1 and in operation motor 44a controls the choke plate for enrichment instead of the motor 44- controlling the recirculation valve 24.
In operation, upon starting the internal combustion engine, when the same has cooled and the afterburner 12 is cooled, the valve in the temperature sensor 42 connected to the vacuum line 47 is open, opening the valve 24, in the system disclosed in FIGURE 1 or preventing the choke plate from being moved to a vertical position in the system disclosed in FIGURE la. This allows an enrichment of the exhaust gases in their concentration of combustibles to the minimum value for aftcrburner operation once it is started. Primary ignition of the exhaust combustibles directed through the discharge tube 10 into the afterburner 12 is accomplished by the spark plug 18 in the combustion chamber 13. After ignition the incinerated gases flow through one of the heat exchangers 14 or 15, depending upon the position of the valve rotor 28, and the corrugated ceramic portion 78 of the heat exchanger absorbs heat from the gas flow as it is directed back to the valve 11 and out through the discharge passage '74 and the outlet tube 17. As aforementioned, every 3 to 5 seconds the direction of the gas flow is reversed by the exhaust valve rotor 23 and the incoming unburned gases to the combustion chamber 13 are then preheated as they flow through the corrugated afterburners 1d and 15. The normal operating temperature within the combustion chamber is generally between 1600 and 2000 degrees F., and when a temperature in excess of about 1800 F. is reached, the temperature sensor 4-2 cuts off the sub-latmospheric pressure in the line 47, cutting off the enrichment system or closing the recirculation valve 24 as shown in FIGURE 1. When the combustion temperatures are above about 1600" F. or higher, no further ignition by the spark plug 18 would be necessary and the spark plug could be deactivated, although this additional control is not deemed necessary or shown in the illustrated system. Under normal driving conditions, combustion chamber temperatures will level out in the 1800 F. to 2000 F. temperature range, dropping below 1700" F. at idle.
During operation of this system, supplemental air for combustion is provided upon starting the internal combustion engine by means of the rotary sliding vane pump 26. The pump 26 along with the intake manifold 6, provide pressurized fluid and sub-atmospheric pressure, respectively, to the plunger operated valve 34, the plunger of which is operated by cam 38 which is driven by the constant speed motor 39. The valve 34 serves to power the fluid motor 29 by evacuating the chamber on one side of the vane 98, using the engine intake manifold subatmospheric pressure, and pressurizing the chamber on the other side of the vane 98 with pressurized air from the pump 26. This insures adequate force to turn the rotor 23 ofthe flow control valve 11, reversing the direction of flow of the exhaust gases through the heat exchangers 14 and 15 of the afterburner 12. As illustrated in FIGURE 1, the exhaust gases enter valve 11 from the discharge tube 10 and are directed by the rotor 28 into the passage 67 and into the plenum area adjacent the distribution plate 5.1. Plate 51 serves to disperse the gases so they flow through substantially the entire corrugated portion 78 of the heat exchanger 15 into the combustion chamber 13. In the combustion chamber the combustible portions of the exhaust gas are ignited by the spark plug or by virtue of their being heated by the heat exchanger 15 and are then directed out through the corrugated portion 78 of the heat exchanger 14, transferring thereto the high heat resulting from combustion. The burned gas is then directed through plate 52 and into the passage 64. From the passage 64 the gas enters the flow control valve 11 and is directed into passage 74 and out the outlet tube 17. The valve 11 is then reversed and the exhaust gas from tube 10 is directed by the rotor 28 into passage 64, through the heat exchanger 14, to the combustion chamber 13. The heat echanger 14 pre-heats the incoming gasesto burn the combustible portions. The incinerated gas passes out through heat exchangers 15, into passage 67, to the valve 11 and out through passage 74 and the outlet tube 17 to complete one cycle. The gas fiow passages 64, 67 and 74 serve to insulate the combustion chamber from the ambient atmosphere around the casing 16 as does the air trapped in the arcuate portion 63 thereof between the baffle plate 70 and the flattened portion 71. This insulating characteristic serves to increase the efiiciency of the afterburner 12.
A marked variation in exhaust combustibles occurs in any one vehicle due to carburetion changes brought about by variations in ambient temperature and pressure. If the exhaust leans out sufiiciently, the combustible concentration may drop below that necessary to sustain afterburner combustion. When this condition arises the temperature within the combustion chamber 13 may drop below 1600" F. (combustion is stable down to about 1500 F.) and if so, the temperature sensor 42 will open the valve subjecting to the line 47 and diaphragm motor to vacuum, which will open the recirculation valve 24, thus causing an enrichment of the combustible concentration in the exhaust gases to sustain afterburner combustion. Under ideal conditions the afterburner can sustain combustion with as little as 1% carbon monoxide in the incoming exhaust gases. However, for practical, reliable operation, at least 2% carbon monoxide should be present in the incoming exhaust for all but transient engine operation and this concentration can be maintained by the tipping of the choke plate or by the recirculation system.
Abnormally high, sustained exhaust combustible concentrations can occur due to a variety of engine malfunctions. Under such conditions, afterburner temperatures could increase to a level sufiiciently high to cause damage to the heat exchangers 14 and 15. Similar conditions may also arise under certain severe driving conditions, such as prolonged upgrade driving with very low intake manifold vacuum. Therefore the safety by-pass is provided, incorporating the second valve within the temperature sensor 42, which will open said valve when the temperature in the combustion chamber exceeds about 2200" F. Opening of this valve subjects the line 48 to vacuum for actuation of the locking device 49 on the motor 29. Operation of this locking device 49 will then stop the vane 98 of the motor 29 in a centered position to place the rotor 28 in the flow control valve 11 in a centered position, such that gases may flow around the ends of said rotor and directly into the passage 74 and out through the outlet tube 17. This interrupts the normal afterburner operation and allows the afterburner unit to cool to prevent any deleterious effect thereon when the aforementioned abnormal condition exists.
The present system has been shown to be highly efficient and will provide continuous operation and many miles of carefree operation due to the automatic regulatory means built into the system for control of the combustible concentrations and for prevention of damage arising from abnormal engine conditions. This makes the present exhaust incineration system adaptable for use on the average automotive vehicle without any change in the carburetion system to enrich the exhaust mixture and is directed to a device which can be readily attached to vehicles now in service.
While the presently preferred embodiments of the present invention have been shown and described, it is to be understood that this disclosure is for the purpose of illustration and that various changes and modifications may be made without departing from the spirit and scope of the invention as set forth in the appended claims.
That which is claimed is:
1. A regenerative afterburner comprising a pair of heat exchangers each of which have a truncated elliptical shape in transverse section and are formed at least partially of corrugated ceramic allowing gaseous flow therethrough between opposite faces, a tubular member having a truncated elliptical shape in transverse section and having open ends with the wall surfaces formed of refractory material to form a combustion chamber therewithin, said member being positioned between said pair of heat exchangers in linear aligned relation with one face of each heat exchanger forming an end wall for said combustion chamber, means adjacent the other face of each heat exchanger to aid in distributing the gaseous flow throughout the corrugated ceramic portion of said heat exchangers when passing therethrough into said combustion chamber, and an elongate casing formed to provide an enclosure for said heat exchangers, said tubular member and said means affording plenum areas adjacent said means, and said casing having passage means formed therein connecting a pair of openings formed in one end of said casing with said plenum areas allowing gaseous flow therethrough to said plenum areas, said heat exchangers and said combustion chamber.
2. An afterburner system for the incineration of the combustible portions of the exhaust gas of an internal combustion engine having an air intake chamber and an exhaust manifold, comprising in combination; a regenerative afterburner comprising at least a pair of heat exchangers formed of corrugated ceramic having a high surface to mass ratio and each having opposed sides for the ingress and egress of exhaust gases, means defining a combustion chamber, said combustion chamber being positioned between and in linear aligned relation with at least said pair of heat exchangers with said side of said heat exchangers forming end walls for said combustion chamber affording straight line gaseous flow through a heat exchanger into the combustion chamber and straight through another heat exchanger, an enclosure member enclosing said heat exchangers and said means defining a combustion chamber; a valve formed with a cylindrical cavity, four ports leading from said cavity and a vane type rotor; passage means connecting one port of said valve in gas flow relation with one of said heat exchangers on a said side thereof opposite said combustion chamber, passage means connecting a second said port with the other of said heat exchangers on a said side thereof opposite said combustion chamber, a third of said ports being adapted to communicate with an outlet tube, a fourth of said ports being adapted to communicate with an engine exhaust manifold, said rotor being rotatably mounted within said cavity, power means connected with said rotor for shifting said rotor from a first position to a second position at periodic intervals for changing the direction of flow of the exhaust gas from a said exhaust manifold through said heat exchangers and out a said outlet tube, means for halting the operation of said power means and for stopping said rotor in a third position at which the flow of the exhaust gas through said heat exchangers is stopped, said halting means being operative upon said combustion chamber reaching a predetermined upper temperature; and a temperature sensor positioned in said combustion chamber affording means for controlling the operation of said halting means such that the same is operative at said upper temperature and rendered inoperative at lower temperatures.
3. An afterburner system according to claim 2 wherein said power means comprises a fluid operated oscillating vane type motor.
4. A regenerative afterburner comprising a casing having a generally elliptical shape in transverse section and forming therewithin an elongate inner chamber of truncated elliptical shape in transverse section and rectangular in plan, a pair of parallel passageways defined in the extreme edge portions of said casing and communicating respectively with opposed ends of said chamber and extending beyond one said end to receive therebetween a control valve, and a third passageway formed in said casing on one side of said chamber from said one said end to the other and adapted to connect to a tail pipe; a control valve positioned between and connected to each passageway and being adapted to connect to an exhaust line direct from an internal combustion engine; a pair of heat exchangers each of which have a truncated elliptical shape in transverse section and are formed at least partially of corrugated ceramic allowing gaseous how therethrough between opposite faces, a tubular member having a truncated elliptical shape in transverse section and having open ends with the Wall surfaces formed of refractory material to form a combustion chamber therewithin, said member being positioned between said pair of heat exchangers in linear aligned relation with one face of each heat exchanger forming an end wall for said combustion chamber, said heat exchangers and said member being positioned within said chamber; and means within said chamber adjacent the other face of each heat exchanger to aid in distributing the gaseous flow throughout the corrugated ceramic portion of said heat exchangers when passing therethrough into said combustion chamber and defining a plenum area between the ends of said chamber and the other face of each said heat exchanger.
5. An afterburner system for the incineration of the combustible portions of the exhaust gas of an internal combustion engine, comprising in combination a regenerative afterburner comprising at least two heat exchangers having a plurality of aligned parallel ordered passageways, means defining a combustion chamber, and passage means defining a gaseous flow path, said combustion chamber being positioned in said gaseous flow path in series relation between two said heat exchangers, an igniter in said combustion chamber, a temperature sensing device in said combustion chamber, a control valve in said flow path for periodically reversing the direction of gaseous flow through said heat exchangers and said combustion chamber, means for actuating said control valve, means for recirculating a portion of the engine exhaust gas through a said internal combustion engine for increasing the concentration of combustible portions of the exhaust gas and including a valve operated by said temperature sensing device and responsive to a predetermined lower temperature within said combustion cham ber to afiord recirculation and to restrict recirculation during normal temperature conditions, means providing supplementary air to the exhaust gas upstream of said control valve affording combustion of the exhaust gas in said combustion chamber, and means operated by said temperature sensing device and responsive to a predetermined upper temperature within said combustion chamber for blocking the flow of the exhaust gas through said afterburner and affording an alternate flow path for said unburned exhaust gas past said combustion chamber and affording a safety device for said afterburner.
References Cited by the Examiner UNITED STATES PATENTS 2,317,582 4/43 Bicknell 1321 19 2,488,563 11/49 Sills -29 2,833,479 5/58 Novesky 60-29 X 2,898,202 8/59 Houdry et a1. 6030 X 3,086,353 4/63 Ridgway 60-30 3,094,394 6/63 Innes et al. 6030 X JULIUS E. WEST, Primary Examiner.
EDGAR W. GEOGHEGAN, Examiner.