US3563029A - Muffler for removing particulate lead from exhaust gases of internal combustion engines - Google Patents

Abstract

MUFFLER FOR AN INTERNAL COMBUSTION ENGINE WHICH IS ADAPTED FOR REMOVING PARTICULATE LEAD MATTER FROM THE EXHAUST GASES OF THE ENGINE TO PREVENT DISCHARGE OF THE NOXIOUS MATTER INTO THE SURROUNDING ATMOSPHERE. BASICALLY, THE MUFFLER COMPRISES A CANISTER OF THE USUAL TYPE EMPLOYED WITH INTERNAL COMBUSTION ENGINES, WHICH HAS AN INLET PORT FOR RECEIVING EXHAUST GASES FROM THE ENGINE AND AN OUTLET PORT FOR DISCHARGING THE EXHAUST GASES TO THE ATMOSPHERE. AN UPWARDLY SLOPING BOTTOM WALL OF THE CANISTER DEFINES A SUMP PORTION ADAPTED TO CONTAIN A FLUX COMPOSITION WHICH IS LIQUID AT THE USUAL TEMPERATURE RANGE OF THE EXHAUST GAS STREAM IN THE CANISTER. A WEIR MEMBER AND ONE OR MORE BAFFLE MEMBERS DEFINE COMPARTMENTS WITHIN THE CANISTER. FLOW OF THE EXHAUST GAS STREAM THROUGH THE CANISTER PROVIDES A DRIVING FORCE WHICH CONTINUOUSLY SPLASHES THE LIQUID FLUX AGAINST THE BAFFLE MEMBER SURFACES AND COMPARTMENT WALLS, THEREBY COATING THESE SURFACES WITH A FLUX FILM MEDIA WHICH ENTRAPS THE LEAD PARTICULATE MATTER IN THE GASES. A SLOTTED EDGE ON THE WEIR MEMBER METERS FLOW OF THE GAS-LIQUID BODY INTO ADJACENT COMPARTMENTS OF THE CANISTER. OPENINGS IN EACH BAFFLE MEMBER, WHICH ARE POSITIONED IN STAGGERED RELATION TO EACH OTHER, PROVIDE A TORTOUS FLOW PATH FOR THE EXHAUST GASES. SMALLER OPENINGS IN THE BAFFLE MEMBERS, TOGETHER WITH AN UPWARDLY SLOPING BOTTOM WALL ON THE CANISTER PERMIT CONTINUOUS FLOWBACK OF THE LIQUID FLUX TOWARD THE FORWARD PORTION OF THE CANISTER. ADDITIONAL FEATURES OF THE MUFFLER INCLUDE (1) A GAS FLOW PORT IN THE WEIR MEMBER, WHICH IS OPENED OR CLOSED BY PRESSURE OF THE EXHAUST GASES, TO PROVIDE FOR GAS FLOW THROUGH THE CANISTER IN THE EVENT OF SOLIDIFICATION OF THE FLUX COMPOSITION; AND (2) FILLING THE REARMOST CHAMBER OF THE CANISTER WITH A POROUS MATERIAL CAPABLE OF TRAPPING AND SEPARATING THE LIQUID FLUX FROM THE EXHAUST GASES.

Description

Feb. 16, 1971 F. J. LOWES 3,563,029

MUFFLER FOR REMOVING PARTICULATE LEAD FROM EXHAUST GASES OF INTERNAL COMBUSTION ENGINES Filed March 13, 1969 INVENTOR. Frea er/ck J. L 0 W95 3,563,029 MUFFLER FOR REMOVING PARTICULATE LEAD FROM EXHAUST GASES OF INTERNAL COM- BUSTION ENGINES Frederick J. Lowes, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Mar. 13, 1969, Ser. No. 806,809

Int. Cl. F01n 3/04 U.S. Cl. 60-30 8 Claims ABSTRACT OF THE DISCLOSURE Mufller for an internal combustion engine which is adapted for removing particulate lead matter from the exhaust gases of the engine to prevent discharge of the noxious matter into the surrounding atmosphere. Basically, the muffler comprises a canister of the usual type employed with internal combustion engines, which has an inlet port for receiving exhaust gases from the engine and an outlet port for discharging the exhaust gases to the atmosphere. An upwardly sloping bottom wall of the canister defines a sump portion adapted to contain a flux composition which is liquid at the usual temperature range of the exhaust gas stream in the canister. A weir member and one or more bafile members define compartments within the canister.

Flow of the exhaust gas stream through the canister provides a driving force which continuously splashes the liquid flux against the battle member surfaces and compartment walls, thereby coating these surfaces with a flux film media which entraps the lead particulate matter in the gases. A slotted edge on the weir member meters flow of the gas-liquid body into adjacent compartments of the canister. Openings in each baflie member, which are positioned in staggered relation to each other, provide a tortuous flow path for the exhaust gases. Smaller openings in the baflle members, together with an upwardly sloping bottom wall on the canister permit continuous flowback of the liquid flux toward the forward portion of the canister. Additional features of the mufller include (1) a gas flow port in the weir member, which is opened or closed by pressure of the exhaust gases, to provide for gas flow through the canister in the event of solidification of the flux composition; and (2) filling the rearmost chamber of the canister with a porous material capable of trapping and separating the liquid flux from the exhaust gases.

BACKGROUND OF THE INVENTION The invention relates to a mufller for an internal combustion engine. More specifically, the invention concerns a muffler adapted to remove particulate lead from the engine exhaust gases, but which also performs the usual function of a mufller as a sound damping device.

Gasolines employed as fuels for the internal combustion engines of automobiles, buses, trucks, and the like, usually contain an additive material which improves the octane rating and gives an anti-knock characteristic to the fuel. The conventional anti-knock additives usually employed in automotive gasolines are tetraalkyl lead compounds, such as tetraethyl lead, tetramethyl lead and mixtures thereof. To prevent lead deposits in the combustion chamber of the engine, however, the leaded fuels usually also contain a scavenger compound such as a mixture of ethylene dichloride-ethylene dibromide. During combustion the scavenger compounds remove the lead components in the form of particulate lead compounds which are carried out of the engine with the exhaust gases.

" United States Patent O Since the conventional automotive mufllers have no means of removing the particulate lead matter, a substantial quantity of this undesirable material is discharged into the atmosphere each day, where it adds to the general air pollution problem and, because of its known toxicity, represents a recognizable health hazard.

OBJECTS OF THE INVENTION A broad object of the invention is to provide a muffler suitable for performing the usual function of damping engine noise, as well as being adapted to remove particulate lead matter from the exhaust gases.

A more specific object is a mufiler containing a flux composition which is a liquid at the temperature of exhaust gases flowing through the mufller, whereby coaction of the exhaust gases with the liquid flux continuously wets inner compartment wall and bafile surfaces of the mufller to provide a media for entrapping particulate lead matter in the exhaust gases.

SUMMARY OF THE INVENTION Broadly stated, the invention provides a mufller for an internal combustion engine, the muffler being adapted to remove lead particulate matter from the exhaust gases of the engine. Basically, the mufller comprises a canister having roll members defining an enclosed vessel with an inlet port for directing an exhaust gas stream into the canister and an outlet port for discharging the exhaust gas stream. The bottom wall of the canister is sloped to provide a sump portion adapted to contain a flux composition which is liquid at the usual temperature range of the exhaust gas stream.

A weir means positioned in the canister at a point downstream from the inlet port is adapted to deflect the exhaust gas stream against the liquid flux contained in the sump portion. The weir means additionally includes a means for regulating displacement of the liquid composition by the exhaust gases from the sump portion. The canister also includes a baflle means positioned within the canister at a point downstream from the weir means, the baffle means being adapted to permit passage of the exhaust gas stream therethrough, the deflection of the gas stream by the bafile creating a tortuous path for the gas through the baffle. A substantial amount of the liquid flux displaced from the sump portion by the exhaust gas stream is continuously directed onto the surface of the baffle and the walls of the canister. Coating of the bafile and wall surfaces with the liquid flux provides a film media which entraps lead particulate matter in the gas stream.

Flux compositions contemplated as suitable lead-trapping media in the mufller of this invention are preferably various inorganic acids, bases and salts which (I) exist as, or are capable of, forming liquid compositions at the usual temperature range of exhaust gases flowing through a mufller, and (2) which will remain stable under such temperature conditions. The usual temperature range of exhaust gases in a conventional automobile engine mufller are from about 500 F. to 1500 F., depending on how close the muffler is located to the exhaust manifold. As regards stability, the flux compositions should be those materials which are not subject to irreversible change with the emission of objectionable vapors. For example, o-phosphoric acid, which is one of the flux compositions useful in the practice of this invention, can convert to polyor pyrophosphoric acid when heated sufliciently to eliminate water in the compound, but will readily revert back to the ortho form when cooled in a humid environment. As a further illustration, carbonates may derive from hydroxides at the lower operating temperatures in a mufller, but the carbonates will form oxides at higher temperatures.

Certain metallurgical fluxes, known commercially as Holden Osquench fluxes, which comprise primarily various mixtures of sodium hydroxide and potassium hydroxide, are particularly preferred in the practice of this invention. These flux compositions are solid materials at room temperature, but readily form liquid compositions on contact with the high temperature exhaust gases in the mufller. Other alkali metal compositions contemplated as suitable fluxes in this invenion include various alkali metal salts, such as sodium acetate, potassium acetate, and mixtures thereof. With regard to acid compositions, commercially available aqueous solutions of orthophosphoric acid have been successfully employed as flux compositions in the mutfier of this invention. Other oxygen acids of phosphorous and acid salts thereof, which are proposed as suitable flux compositions, include hypophosphoric acids, pyrophosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodiurn phosphate and the like.

Materials used to fabricate the canister and the configuration of the device itself are not considered critical. Metals having high corrosion resistance are preferred for obvious reasons. Suitable materials include certain cladded metals such as iron-stainless steel, iron-aluminum, iron-titanium, and the like. For ease of fabrication the preferred shape of the canister is either the usual cylindrical or elliptical shape of the conventional automotive mufflers or the substantially rectangular shape of the muffler illustrated herein. Other factors which should determine the preferred shape of the canister include (1) the ability of the device to remove lead from exhaust gases and (2) the capability of the muffler to function as a sound damper for engine noise.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation view, partly in section, of a rnuflller according to a preferred embodiment of the invention.

FIG. 2 is a cross-sectional view, taken along line 22 of FIG. 1, which illustrates a weir member as positioned in the muffler.

FIG. 3 is a cross-sectional view, taken along line 3-3 of FIG. 1, which illustrates a baflle member, as positioned in the muffler.

FIG. 4 is a cross-sectional view, taken along line 4-4 of FIG. 1, which illustrates a second batflle member, as positioned in the mufiler.

The drawing illustrates only one of numerous embodiments within the scope of the invention and the form shown is selected for convenient illustration and clear demonstration of the principles involved.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawing, with particular reference to FIG. 1, there is illustrated a muffler similar in construc tion to the usual type employed as a sound damper on an internal combustion engine. The mufiler comprises basically a canister 10, providing a generally enclosed vessel, as defined by an upstanding front wall 12 and an up standing rear wall 14, which are connected by a generally horizontally-disposed top wall 16, and a bottom 'wall 18, the bottom wall sloping generally upwardly from the front wall to the rear wall of the canister. Additionally, a pair of upstanding sidewalls 19 and 20, as best shown in FIG. 2, join the front and rear walls .12 and 14 with top and bottom walls 16 and 18, giving the canister a generally rectangular configuration. The front wall 12 of canister 10 includes an inlet port 21, which is adapted for connection to the exhaust pipe of a conventional automobile engine to receive exhaust gases from the engine. The exhaust gases are discharged from the canister .10 through an outlet port 22, which is located in the 4 rear wall 14 of the canister and is adapted for connection to the tail pipe of an automobile engine.

As illustrated in FIG. 1, the preferred embodiment of the canister 10 is divided into a series of compartments. A first compartment 24 is defined by a weir member 26, which is generally vertically disposed in the canister '10 and spaced from the front wall 12 thereof. A first baffle member 28, which is generally vertically disposed in the canister and spaced behind the weir member 26, defines a second compartment 30. A second generally vertically disposed bafile member 32, which is spaced behind the first baffie member 28, defines a third compartment 34. A fourth (or rear) compartment 36 is defined by the space between the baffle member 32 and the rear wall 14 of canister 10.

The upwardly sloping bottom Wall 18 defines generally a sump portion (not numbered), which is subdivided into the compartments 24, 30, 34 and 36. That portion of the sump as defined by the compartments 24, 30 and 34 provides a container for a flux composition 38, the flux composition being present in the canister 10 as a liquid at the temperature range of the exhaust gases flowing through the canister. As indicated by the arrows in FIG. 1, the exhaust gases flowing through the canister act as a driving force to continuously splash the liquid flux against the walls of the compartments 30 and #34 and the surfaces of bafile members 28 and 32. This splashing action coats the bafile and compartment Wall surfaces with a flux film media which entraps particulate lead matter in the exhaust gases.

As best shown in FIG. 2, a plurality of generally V- shaped slots 40, which define the bottom edge of weir member 26, provide means for distributing and regulating rearward flow of the exhaust gases and displacement of the liquid flux composition 38 within the canister 10. The exhaust gases are constrained to follow a tortuous path in their flow through the canister 10, as provided by the series of openings 42 in bafiie member 28, and similar opening 44 in bafiie member 32, the openings being staggered relative to each other so that the gases cannot flow in a straight line. By providing a tortuous path for the exhaust gases, the particulate lead matter in the gases, which tends to travel in straight lines, is induced to strike the compartment walls and baffle surfaces Where it clings to the flux film coating on these surfaces.

The sump portion provided by the sloping bottom wall 13, in conjunction with the smaller openings 46, positioned along the bottom edge of bafile member 28, and the similar openings 48 in bafile member 32, permit the return (or forward) flow of the flux composition 38 in canister 10. By this means, therefore, the flux composition may be maintained at at all times at the desired operating level in the canister. During flow of the exhaust gases through canister 10, small amounts of the flux composition 38 may be carried over into compartment 36 by the exhaust gases, and thereby be accidentally discharged from the canister through outlet port 22. T o prevent such loss of the flux composition, the compartment 36 may be filled with a porous material 50, such as steel wool, which will trap and separate the liquid fiuX from the exhaust gases. The separator material 50 is considered optional equipment, since it is not required for normal operation of the canister 10.

In the event of solidification of the liquid flux composition 38, such as during cold weather operation, a gas flow port in the weir member 26 provides for uninterrupted flow of exhaust gases through the canister '10. The gas flow port is defined by an aperture 52 in weir member 26 and a closure member 54 mounted on the rearward side of weir member 26 in direct alignment with aperture 52. To provide for opening and closing of the aperature 52, the closure member 54 is biased against weir member 26 by a spring hinge or other suitable biasing means. During normal operation of the canister 10 the aperture 52 is closed, that is, the closure member 54 remains biased against weir member 26. Should the liquid flux composition 38 solidify, however, the pressure of the incoming exhaust gases in canister 10 soon becomes high enough in compartment 24 to force closure member 54 open. This permits the exhaust gases to flow through the weir member 26, rather than under the weir member in the intended manner. As soon as the heat from the exhaust gases flowing into compartment 24 is able to convert the solid flux composition to a liquid, usually a very short time, the canister will resume its normal operation.

The canister 10 may be filled with flux composition 38 through a filler cap 56, which is mounted on the upper wall 16 to provide access to the (forward) compartment 24. Although separate filler caps for compartments 30 and 34 may be provided when the flux composition 38 is a solid material as initially charged to the canister 10, such additional filler caps are not considered essential to the practice of the invention. In other words, the compartment 24 may be charged with a sufiicient amount of solid flux composition to provide the desired liquid level in compartments 30 and 34 as the flux is liquefied by the exhaust gases. When it is desired to clean the canister 10 or to replace the flux composition with a fresh solution, the canister may be drained through a petcock 58 mounted on the bottom wall 18 at the forward end of compartment 24.

OPERATION In a typical operation, the capability of the present muffler to remove lead particulate matter from engine exhaust gases was demonstrated by employing the canister 10 in a series of test runs on a conventional multicylinder automobile engine. The tests were run on a Ford V-8 engine, 289 cu. in., single exhaust. The fuel used was a conventional leaded gasoline of the type generally employed in research studies of internal combustion en- 1 the procedures described herein:

Example I In the first run the flux composition 38, as charged to the canister '10, was a solid material comprising essentially a mixture of sodium hydroxide and potassium hydroxide (hydrate), know commercially as Holden Osquench 330040. Analysis of the flux composition by known procedures revealed that it contained on lead components.

The engine was started and allowed to run at 2000 r.p.m. for about 30 minutes under no-load (idling) conditions. During this time the exhaust gas pressure at the manifold was balanced against the pressure in the canister and the exhaust gases were allowed to flow freely through the canister. After the initial warm-up period the flux composition was added to the canister 10 and the engine was allowed to run for an additional 30-minute period to stabilize the engine operating conditions, such as the desired r.p.m., operating temperature and rebalance of the exhaust gas pressure. The engine was then run continuously for a period of about 9 hours, with exhaust gases flowing through the canister during the entire period. During the run the vacuum pressure was gradually decreased in increments of 2 in. Hg, from idle to wide open throttle, while holding the engine at 2000 rpm. At the end of the 9-hour period the engine was shut off and the canister 10 allowed to cool to room temperature.

Five samples of the flux composition were obtained 6 at various places in the canister 10, ranging from the forward portion to the rear portion thereof, with each sample being analyzed for lead content. Reading from front to rear of the canister, the lead content of the respective samples was as follows (computed as percent by weight of sample): Sample 10.003%; Sample 20.l5%; Sample 30.09%; Sample 4-0.029% and Sample 5l.5%.

Example II In the second run the flux composition 38, as charged to the canister 10, was a solid material comprising essentially a mixture of sodium hydroxide and potassium hydroxide, with trace amounts of potassium chloride, known commercially as Holden Osquench 300.

The test procedure and engine operating conditions were essentially those described in Example I, with the engine being allowed to run continuously for a period of about 26 hours. After the canister 10 was allowed to cool to room temperature, three (3) samples of the flux composition were obtained at various points within the canister as follows: Sample 1 was taken from the surface of the flux composition in compartment 24; Sample 2 was taken from the center of the flux composition in compartment 30; and Sample 3 was taken from the forward surface of bafile member 32. Lead content analysis of each sample gave the following result (computer as percent by weight of sample): Sample 1-0.3%; Sample 20.01%; and Sample 3-0.6%.

Example III For the third test run the flux composition 38, as charged to the canister 10, was a liquid composition comprising a commercially available aqueous solution of orthophosphoric acid.

The procedure and engine operating conditions were essentially those set out in Example I, with the engine being run continuously for a period of about 19 hours. After the canister .10 was allowed to cool, three (3) samples of the flux composition were obtained at the same positions in the canister as the samples of Example II. Analysis of the respective samples for lead content gave the following results (computed as percent by weight of sample): Sample 10.l5%; Sample 20.l7%; and Sample 30.20%.

As the data of the foregoing examples clearly indicate, the mufller of this invention effectively removes a substantial quantity of the lead component present in the exhaust gases of internal combustion engines. -In additional experiments conducted in the practice of this invention, it was found that (l) the sound damping characteristics of the present mufiier are at least equivalent to conventional mutfier, and (2) the back pressure of the present muffler is significantly less than that of the conventional mufflers.

What is claimed is:

1. Method for removing lead particulate matter from the exhaust gases of an internal combustion engine, which comprises:

providing in the exhaust system of the engine an enclosed canister including an inlet port, a weir means positioned downstream from the inlet port and having thereon a liquid flow regulating means, at least one baffle means having openings therein and positioned downstream from the weir means, a sump portion positioned below the weir means and containing a flux composition comprising an inorganic acid, base or salt which is a stable, liquid composition at a temperature of from about 500 F. to 1500 F., and an outlet port positioned downstream from the baflie means;

directing the lead-containing exhaust gas stream through the inlet port into the canister;

deflecting the gas stream against the weir means to direct it downwardly against the liquid flux; displacing with the exhaust gas stream a substantial amount of the liquid flux from the sump portion through the liquid flow regulating means of the weir means; continuously splashing the displaced liquid flux against the bafi'le means with the exhaust gas stream to coat the bafile surface with a film of the liquid flux;

directing the exhaust gas stream through the openings in the bafile means, while impinging the particulate lead matter against the baffle surface to entrap the particles in the fiux coating thereon;

discharging the exhaust gas stream from the canister through the outlet port.

2. The method of claim 1 in which the flux composition is an alkali metal base selected from the group consisting essentially of sodium hydroxide, potassium hydroxide, and mixtures of sodium hydroxide and potassium hydroxide.

3. The method of claim 1 in which the flux composition is an alkali metal salt selected from the group consisting essentially of sodium acetate, potassium acetate, and mixtures of sodium acetate and potassium acetate.

4. The method of claim 1 in which the flux composition is an oxygen acid of phosphorous selected from the group consisting of orthophosphoric acid, hypophosphoric acid and pyrophosphoric acid.

5. The method of claim 1 in which the flux composition is an oxygen acid salt of phosphorous selected from the group consisting of sodium dihydrogen phosphate, disodium hydrogen phosphate and trisodium phosphate.

6. In the exhaust system of an internal combustion engine, a muffler for removing lead particulate matter from the exhaust gases of the engine, which comprises:

(I) a canister generally defining an enclosed vessel which has:

(A) an inlet port for directing an exhaust gas stream into the canister;

(B) an outlet port for discharging the exhaust gas stream from the canister;

(C) a front wall;

(D) a rear wall;

(E) a top wall and side walls connecting the front and rear walls;

(F) a bottom wall connecting the front and rear walls and sloping upwardly from the front wall to the rear wall to define a sump portion in the canister;

(G) the said sump portion containing a flux composition which is a stable, liquid composition at a temperature of from about 500 F. to 1500 E;

(II) a weir means which:

(A) is substantially vertically disposed within the canister;

(B) is spaced from the front wall of the canister to define a first compartment in the sump portion;

(C) is adapted to deflect the gas stream downwardly against the flux composition contained in the first compartment of the sump portion;

(D) has liquid flow regulating means thereon for 60 regulating displacement of the fiux composition from said first compartment;

(E) has an aperture therein which is positioned above the liquid fiow regulating means and a clo- '8 sure member for the aperture which is mounted on the weir means in alignment with the aperture, the closure member being biased against the weir means to permit opening of the aperture in response to pressure of the exhaust gas stream against the closure member;

(III) a first baffle means which:

(A) is substantially vertically-disposed within the canister;

(B) is spaced from the weir means to define a second compartment in the sump portion of the canister;

(C) has gas-flow openings therein;

(D) has liquid flow openings therein, said openings being positioned in the bafile below the gasflow openings;

(IV) a second bafile means which: 9

(A) is substantially vertically-disposed within the canister;

(B) is spaced from the first bafile means to define a third compartment in the sump portion of the canister;

(C) is spaced from the rear wall of the canister to define a fourth compartment in the sump portion of the canister;

(D) has gas-flow openings therein;

(E) has liquid-flow openings therein, said openings being positioned in the bafl1e below the gas-flow openings;

(F) whereby deflection of the exhaust gas stream downwardly against the flux composition contained in the first compartment displaces a portion of the flux composition from the first compartment into the second and third compartments, in which compartments the displaced flux continuously splashes against the first and second bafile means to coat the surfaces of said baffie means with a flux film which entraps lead particulate matter impinging on said film.

7. The mufller of claim 6 wherein the liquid flow regulating means on the weir means comprises a plurality of generally V-shaped slots which define the bottom edge of the weir means.

8. The muffler of claim 6 wherein the fourth compartment of the canister includes means for separating the liquid flux composition from the exhaust gases.

References Cited UNITED STATES PATENTS DOUGLAS HART, Primary Examiner US. Cl. XR.

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