EP0563882B1 - Verfahren zur katalytischen Reinigung der Abgase einer Brennkraftmaschine und Abgasvorrichtung - Google Patents

Verfahren zur katalytischen Reinigung der Abgase einer Brennkraftmaschine und Abgasvorrichtung Download PDF

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Publication number
EP0563882B1
EP0563882B1 EP93105250A EP93105250A EP0563882B1 EP 0563882 B1 EP0563882 B1 EP 0563882B1 EP 93105250 A EP93105250 A EP 93105250A EP 93105250 A EP93105250 A EP 93105250A EP 0563882 B1 EP0563882 B1 EP 0563882B1
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EP
European Patent Office
Prior art keywords
exhaust gas
catalytic converter
converter body
muffler
expansion chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93105250A
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English (en)
French (fr)
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EP0563882A1 (de
Inventor
Hiromi Suzuki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yamaha Motor Co Ltd
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Yamaha Motor Co Ltd
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Filing date
Publication date
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Publication of EP0563882A1 publication Critical patent/EP0563882A1/de
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Publication of EP0563882B1 publication Critical patent/EP0563882B1/de
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Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/08—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling
    • F01N1/084—Silencing apparatus characterised by method of silencing by reducing exhaust energy by throttling or whirling the gases flowing through the silencer two or more times longitudinally in opposite directions, e.g. using parallel or concentric tubes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2053—By-passing catalytic reactors, e.g. to prevent overheating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2839—Arrangements for mounting catalyst support in housing, e.g. with means for compensating thermal expansion or vibration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2882—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices
    • F01N3/2885—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices with exhaust silencers in a single housing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2490/00—Structure, disposition or shape of gas-chambers
    • F01N2490/02—Two or more expansion chambers in series connected by means of tubes
    • F01N2490/06—Two or more expansion chambers in series connected by means of tubes the gases flowing longitudinally from inlet to outlet in opposite directions

Definitions

  • the present invention relates to a method for catalytically cleaning the exhaust gas of an internal combustion engine having a catalytic converter body disposed in a muffler of an exhaust gas system thereof. Moreover, the present invention relates also to an exhaust gas system of an internal combustion engine, particularly for performing said method.
  • catalytic converters having catalysts, disposed in the exhaust gas system of the engine are conventional.
  • Such catalytic converters are subject to extreme thermal conditions which shortens the lifetime of the catalysts and, moreover, also require a certain operating temperature in order to clean the exhaust gases from the engine sufficiently.
  • there is a certain drop of chemical activity from the upstream entry side to the downstream discharge side of the catalytic converter resulting from a reduction of the oxygen content in the exhaust gas which renders combustion of the unburnt hydrocarbons at the downstream discharge side of the catalytic converter insufficient.
  • mufflers have been equipped with a catalytic converter and also motorcycles have been equipped with such mufflers.
  • catalytic converters have been installed on both upstream and downstream portions of the exhaust passage in order to promote the cleaning of the exhaust gas exhausted from the engine.
  • an upstream side catalytic converter should be disposed in the exhaust passage as remote as possible from the engine.
  • a muffler may comprise a relatively large-sized catalytic converter which is separated into an upstream part and a downstream part thereof with opposite flow conditions wherein the exhaust gas is introduced from one end either into its centre portion or into its lower half portion, reversing the exhaust gas which has passed through said portion of the catalytic converter at the other end thereof and reintroducing the flow of exhaust gas into the catalytic converter for opposite flow either along a annular peripheral portion of the catalytic converter or an upper half thereof.
  • the afore-indicated objective in view of its method aspects is performend in that a total flow of exhaust gas is subdivided into a plurality of partial flows of exhaust gas, a partial flow of exhaust gas is fed through a first branch of said catalytic converter body and then the recombined total flow of exhaust gas is fed through a second branch of said catalytic converter body.
  • a part of the incoming flow of exhaust gas is branched off of the total flow of exhaust gas, said part being fed through an upstream cleaning catalyst and, then, the recombined total flow of exhaust gas is fed through a downstream cleaning catalyst disposed in said muffler.
  • a pre-cleaning of a part of the total flow of exhaust gas takes place at the area of the first branch of the catalytic converter body and that said pre-cleaned part of the exhaust gas is then recombined with the rest of the total flow of the exhaust gas to be fed through the second branch of the catalytic converter body disposed in said muffler.
  • recombination of a pre-cleaned part with the remainder part of the total flow of exhaust gas takes place, said pre-cleaned part was fed through a portion of the catalytic converter body only while then recombination of the two flows of exhaust gas takes place for feeding said partially treated flow, total flow of exhaust gas to the remainder part of the catalytic converter body which defines a downstream part thereof.
  • a part of the catalytic converter is subject to a part of the crossectional volume of the total flow of exhaust gas whereas downstream of the catalytic converter recombination takes place to feed the remainder portion of the catalytic converter body.
  • This can be obtained by either partially disposing the catalytic converter body into a part of the crosssection of the exhaust pipe or, for example, by branching off a partial flow of exhaust gas from the exhaust pipe by a separate guide means and feeding a part of the cross-section of the catalytic converter body therewith.
  • the present invention sets forth an improvement in that the catalytic converter body comprises a first branch passageway through which a partial flow of an incoming total flow of exhaust gas is fed, and a second branch passageway through which the recombined total flow of exhaust gas is fed.
  • the exhaust gas is partly cleaned by the catalytic converter body when passing through a part of the catalytic converter body (upstream portion) whereas the total volume of exhaust gas is further cleaned when passing through the remainder part of the catalytic converter body.
  • the partially pre-treated total volume of exhaust gas is introduced in a downstream side part of the catalytic converter body with a sufficient amount of oxygen left therein so that the cleaning performance of the catalytic converter body will not be deteriorated even though a single catalytic converter body is only used to clean the exhaust gas in two stages. Therefore a superior cleaning effect can be obtained even beyond a structure of two catalytic converters disposed in an exhaust passage whereas the muffler is prevented from becoming bulky.
  • the temperature difference along the catalytic converter is considerably reduced because the exhaust gas is efficiently cleaned in both sections of the catalytic converter body without over-stressing the entry portion thereof. Moreover, because the heat of the exhaust gas at the first branch passageway of the catalytic converter body is transmitted through heat conduction to the second branch passageway of the catalytic converter body temperature difference along the converter is reduced. Thus, malfunctin of the catalytic converter body due to thermal overstress can be avoided. Moreover, balanced conditions for buring unburnt hydrocarbon constituents also adds to a more equal temperature profile along the catalytic converter.
  • the first branch passageway of the catalytic converter body (through which the branched off partial flow of the exhaust gas flows) is disposed to the exhaust gas at a more upstream position where the exhaust gas has a relatively high temperature the cold starting cleaning capabilities of the catalytic converter body are improved as the exhaust gas can be cleaned even in a more early stage after starting of the engine.
  • the exhaust gas is sent to the second branch passageway of the catalytic converter body in a already partly cleaned and heated condition its temperature drop is small. Therefore, the exhaust gas can also efficiently be cleaned even in the second downstream stage of the catalytic converter body.
  • the catalytic converter body comprises a single catalytic converter body disposed within said muffler.
  • a preferred disposal of the catalytic converter body is that it partially projects into an end portion of the exhaust pipe through a recessed side wall of said pipe. In this way a part of the total flow of exhaust gas passes through that part of the catalytic converter which projects into the exhaust pipe.
  • the catalytic converter is disposed laterally outwardly of the exhaust pipe and a exhaust gas passageway means is provided branching off of the exhaust pipe upstream of the catalytic converter to lead a part of the exhaust gas to an upstream part of the catalytic converter which, on the other hand, establishing a downstream portion of said branching of guiding exhaust gas passageway means.
  • a recombination of said partial flow of pre-cleaned exhaust gas with the remainder un-treated parts of the exhaust gas volume is performed.
  • said muffler comprises a plurality of expansion chambers which are separated by recessed baffle plates and are disposed successively along a longitudinal axis of the muffler.
  • the catalytic converter is disposed to connect an upstream expansion chamber to a more downwardly disposed expansion chamber of the muffler reaching a downstream expansion chamber from which an exhaust gas discharge extends forward outside.
  • the outlet of the exhaust pipe opens into the rearmost expansion chamber from which a reverse flow of the exhaust gas forwardly is established through a centre expansion chamber, then through a main portion of the catalytic converter to a front expansion chamber and then to the downstream expansion chamber toward outside.
  • a motor scooter 1 comprises an internal combustion engine 2 forming a swing-type unit for driving a rear wheel 3. Said internal combustion engine 2 is supported on a frame 1a of the motor scooter 1 for vertical swinging. Said engine 2 is oriented such that its cylinder may be directed generally forwardly so as to be accommodated in a space saving manner.
  • a container box lc is installed under a drivers seat 1b.
  • an exhaust gas pipe 4 Connected to an exhaust port (not shown) of the internal combustion engine 2 is an exhaust gas pipe 4 terminating into a muffler 5 disposed on a rear end portion of the exhaust pipe 4.
  • the exhaust pipe 4 extends rearwardly under the engine 2 from a lower portion of the forwardly directed cylinder of the engine 2.
  • the muffler 5 is composed of muffler bodies 6, 7 formed separately as left and right halves and a catalytic converter 8 is accommodated within this space defined through said muffler bodies 6, 7 as shown in Fugures 2 & 3.
  • Each muffler half 6 or 7 is shaped generally circularly in cross section and such that its diameter may gradually reduce towards its front end rear ends, respectively.
  • Each muffler half body 6 or 7 comprises flanges 6a, 7a formed along its margins.
  • the muffler 5 is formed and assembled by seam-welding of these flanges 6a, 7a to each other after installing the catalytic converter body 8 and buffle plates 9, 10 & 11 (described hereinafter) are disposed spaced along the longitudinal axis of the muffler half bodies 6 & 7.
  • the exhaust pipe 4, more specifically the end portion 4b thereof is inserted and secured on the muffler 5 with its outlet opening 4c to the rear end of the interior of the muffler 5.
  • expansion chambers (A,B,C and D) are formed by means of three fixed baffle plates 9,10 and 11) which are penetrated by the exhaust pipe 4.
  • the rearmost expansion chamber (D) to which the rear end opening 4c of the exhaust pipe 4 faces is communicated to a centre expansion chamber C through an opening 11a formed through the baffle plate 11 and said central expansion chambers C, in turn is communicated to the frontmost expansion chamber A through the catalytic converter 8 supported through the cross-walls or separating baffle plates 9,10.
  • said muffler (5) is provided with a reversing passage having a catalytic converter (8) installed in it as a bridging member and is formed such that the length of the exhaust pipe may be become as long as possible.
  • the foremost expansion chamber A into which a front portion of the catalytic converter 8 (actually, under flow conditions, it is the downstream side of the catalytic converter 8) opens is communicated to a downstream expansion chamber B (which is bypassed through the catalytic converter 8) through a communicating pipe 12 supported by the foremost baffle plate 9.
  • the downstream expansion chamber B is communicated to the exterior of the muffler 5 through an exhaust discharge pipe 13 which penetrates the baffle plates 10 and 11 and the muffler body 6 to be supported by said elements.
  • the catalytic converter 8 is formed generally cylindrically as shown in Figures 2 & 3 penetrating the baffle plates 9 and 10 to be supported by same bridging the downstream expansion chamber B to connect the centre expansion chamber C fluidly to the more downwardly disposed, forward expansion chamber A.
  • the catalytic converter 8 in a cross sectional direction, comprises an upstream part 8A and a downstream part 8B, said upstream part 8A projecting into the end portion 4b of the exhaust pipe 4. Accordingly said end portion 4b of the exhaust pipe 4 is partly cut-out to allow the catalytic converter 8 to be inserted through said recess for partially projecting into the exhaust gas flow channel as defined by the exhaust pipe b.
  • an intimate connection is formed sealingly by welding.
  • the catalytic converter 8 specifically its upstream part 8A, projecting into the rear end 4b of the exhaust pipe 4 is disposed and oriented such that there is a smooth permability for the exhaust gas from an entry side of said upstream part 8A to an outlet side thereof.
  • Each of the two baffle plates 9,10 supporting the catalytic converter 8 has a generally gourd-shaped hole formed therethrough as shown in Figure 3 and the downstream expansion chamber B is partitioned from the adjacent expansion chambers A and C by sealingly leading said catalytic converter 8 and the exhaust pipe 4 through said gourd-shaped holes.
  • the cross sectional area of the projecting part 8A of the catalytic converter 8 facing the exhaust gas within the rear end 4b of the exhaust pipe 4 is desirable to be smaller than two thirds of the total cross section of the catalytic converter 8.
  • the cross section of said projecting part 8A of the catalytic converter 8 should be smaller than two thirds of the cross section of the exhaust pipe 4 at that region so as to set the quantity of volume of exhaust gas flowing through said projecting upstream portion 8A of the catalytic converter 8 projecting into the exhaust pipe 4 to be smaller than two thirds of the total quantity of exhaust gas flowing through said exhaust pipe 4.
  • FIG. 3 In the cross section of Figure 3 one configuration of the catalytic converter 8 is shown having a honeycomb-shaped structure.
  • Figure 4 shows another embodiment of the catalytic converter 8. In said Figure 4 the central portion is shown in a larger scale in order to facilitate understanding and explanation of the structure of said other embodiment of a catalytic converter 8 which, of course, could also be used in the embodiment of Figure 3 instead of the catalytic converter 8 having a net-like honeycomb-shaped structure.
  • the catalytic converter 8 according to Figure 4 is also formed cylindrically with a wound honeycomb-like cross section by winding a flat band foil 8a and corrugated band foil 8b spirally lapping one above the other.
  • both surfaces of either the flat foil 8a or the corrugated foil 8b are covered with a thin flat plate-like solder and the solder covered foil is piled over the other foil with their front ends trued up and nipped together with a chig to form a band-like material which, when being wound up, forms a wound honeycomb-like structure.
  • the flat foil 8a and the corrugated foil 8b are wound up around themselves together with the solder and the foils thus formed cylindrically are soldered on each other by heating said wound bobbin in a furnace.
  • the fore-described method for adhering the catalysts to the column-like support member to carry same not only the fore-described method can be used but one of various conventional methods can be applied, for example a method in which the wound up cylindrical support structure at first is coated only with aluminium and then is subject to carry catalytic metals as catalysts.
  • the exhaust gas discharged from the engine 2 enters from the exhaust pipe 4 through the rear end 4b thereof and the outlet opening 4c into the rearmost expansion chamber D and the muffler 5 and is reversed from there into the centre expansion chamber C through an opening 11a of the baffle plate 11.
  • the exhaust gas flowing into the expansion chamber D through the exhaust pipe 4 passes through said projecting upstream part 8A of the catalytic converter 8 projecting into the exhaust pipe 4 (or the rear end 4b thereof) and is cleaned in that upstream part 8A.
  • the catalytic converter 8 is designed to have a honeycomb-like gas cleaning structure and its gas flowing portions are partioned from each other (as derivable from the different cross sections of the two embodiments shown in Figures 3 & 4), the exhaust gas in the exhaust pipe 4 will never leak out into the downstream expansion chamber B bypassed by the catalytic converter 8. Accordingly the total flow of exhaust gas fed from the expansion chamber D to the centre expansion chamber C is in a partly cleaned state.
  • said upstream part 8A of the catalytic converter 8 projecting into the exhaust pipe 4 is heated by the exhaust gas having a relatively high temperature.
  • the heat is conducted to the downstream part 8B on the side of the expansion chamber B through the flat foil 8a and the corrugated foil 8b.
  • the overall temperature of the catalytic converter 8 rises and is distributed more evenly across the catalytic converter 8 and the exhaust gas is sufficiently cleaned from an early stage at once after engine starting.
  • the exhaust gas is partly cleaned by the upstream part 8A of the catalytic converter 8 projecting into the exhaust pipe 4 and is recombined downstream of said upstream part 8A of the catalytic converter 8 to be discharged from the outlet 4c into the expansion chamber C in a partly cleaned condition. Then the total flow of exhaust gas is completely cleaned passing through the downstream part 8B of the catalytic converter 8 from the central expansion chamber C.
  • the cleaning performance of the catalytic converter means will not be lowered although exhaust gas is cleaned in two stages by allowing a part of the total flow of exhaust gas to pass through the upstream part 8A of the catalytic converter and by passing through the recombined total flow of exhaust gas through the downstream part 8B of the catalytic converter 8 establishing said cleaning in two stages by said single catalytic converter 8.
  • the temperature difference across the catalytic converter 8 between its upstream part 8A projecting into the exhaust pipe 4 and its downstream part 8B extending outside of the exhaust pipe 4 and subject to the total flow of exhaust gas which is in a partly pre-cleaned state becomes smaller as the exhaust gas is sufficiently cleaned in both sections 8A, 8B of the catalytic converter 8.
  • a more even distribution of temperature is triggered also by the fact that the heat of the exhaust gas flowing through the exhaust pipe 4 and from the heated wall portions of the rear end 4b of the exhaust pipe 4 in contact with the catalytic converter 8 is transmitted from said upstream part 8A to the downstream part 8B of the catalytic converter 8 by heat conduction with very low heat resistance.
  • an upstream end of the exhaust pipe is positioned on the lower side of the engine and its overall length is apt to become shorter when a container box is installed under the seat 11b of the motor scooter 1 disposing the engine to such that its cylinder is directed forward as shown in Figure 1, the effective length of the exhaust pipe 4 can be expanded and sufficiently assured by means that a reversing passage can be formed in the muffler 5 utilising the catalytic converter 8 within said flow passage.
  • FIG. 5 and 6 Another embodiment of the present invention is shown in Figures 5 and 6 which differs from the afore-described embodiment of Figure 2 substantially in that the catalytic converter 8 does no longer project into the exhaust pipe 4 but is in its entirety disposed separately laterally of the exhaust pipe establishing a sub-divided upstream and downstream regions 8A, 8B of the catalytic converter by means of a specific exhaust gas passage means 21 through which a branched off partial flow of exhaust gas is fed to the upstream part 8A of the catalytic converter 8.
  • the catalytic converter 8 is disposed outside of the exhaust pipe 4 laterally thereof.
  • the baffle plates 9 and 10 supporting the catalytic converter 8 are formed similar to that used in the embodiment of Figure 4.
  • the reference numeral 21 denotes an exhaust gas passageway means 21 for introducing a part of the exhaust gas from the exhaust pipe 4 into the upstream part 8A of the catalytic converter 8.
  • said passageway means 21 guiding a partial flow of the exhaust gas to the upstream part 8A of the catalytic converter 8 is formed in an inversed U-shaped cross section and is welded onto the outer surface of the exhaust pipe 4 at the lower end portions of two side walls 21a extending downwards in Figure 6.
  • the rear end of the side wall 21a is pushed against and welded on the baffle plate 9.
  • the connections between the side walls 21a with the exhaust pipe 4 and the baffle plate 9 are sealed by welding.
  • An upper wall 21b of said exhaust gas introducing passageway means 21 extends from a position opposite to an exhaust gas outlet port 4a opening through the wall of the exhaust pipe 4 to a front end portion of the catalytic converter 8 with a rear upwards inclination.
  • the rear end of the upper wall 21b is positioned at the front end of the catalytic converter 8 below a centre of same as shown in Figures 5 and 6, thus defining the upstream part 8A and the downstream part 8B of the catalytic converter 8.
  • the centre expansion chamber C In the centre expansion chamber C the partial flow of exhaust gas passing through the upstream part 8A of the catalytic converter 8 and cleaned therein and the main flow of exhaust gas passing through the exhaust pipe and the rear outlet 4c thereof to be reversed in the rearmost expansion chamber D to be fed from the rear into the centre expansion chamber C through the opening 11a of the baffle plate 11 join in the centre expansion chamber C to flow for substantial cleaning into the downstream part 8B of the catalytic converter 8.
  • the exhaust gas is partly cleaned by the upstream part 8A of the catalytic converter 8 when a branched off partial flow of the exhaust gas is passed through the catalytic converter 8 to the centre expansion chamber C and, then, complete cleaning of the total flow of exhaust gas after said partial flow of pre-cleaned exhaust gas is recombined with the reaminder main flow of exhaust gas in the central expansion chamber C the catalytic converter 8, namely the downstream part 8B thereof takes place when the total flow of exhaust gas flows from the centre expansion chamber C through the downstream part 8B of the catalytic converter 8 to the front side expansion chamber A.
  • the cleaning performance will not be deteriorated although a single catalytic converter is being used and cleaning of the exhaust gas is sub-divided in upstream and downstream parts through the catalytic converter. Aside from a sufficient cleaning effect and capacity of such a structure the muffler is prevented from becoming larger sized due to the specific design and flow conditions inside the muffler.
  • the temperature difference across the catalytic converter specifically between its upstream part through which exhaust gas is allowed to flow at an upstream area and its downstream portion through which exhaust gas is allowed to flow after having partially passed through the upstream part of the catalytic converter is reduced as the exhaust gas is efficiently cleaned in both the upstream and downstream portions of the catalytic converter and, moreover, as the heat of the upstream part of the catalytic converter is effectively transmitted through heat conduction to the downstream part of the catalytic converter through which the exhaust gas at a downstream side is passed through. Therefore, thermal distortion of the catalytic converter does not occure and the catalytic converter is prevented from being broken of deformed.
  • Said effect is promoted by a sufficient afterburning of unburnt hydrocarbons in the downstream part of the catalytic converter resulting from a sufficient amount of oxygen being present there so that a temperature difference between the upstream and downstream parts 8A, 8B of the catalytic converter 8 is reduced. This adds to avoid thermal distortion or break, deformation etc., of the catalytic converter.
  • the upstream part 8A of the catalytic converter 8 is disposed in the region of a relatively high temperature the exhaust gas rapid warming up of said part 8A of the catalytic converter takes place and the exhaust gas can be cleaned even in a very early stage after engine starting.
  • the temperature of the exhaust gas forwarded to the downstream part 8B of the catalytic converter 8 is elevated due to the mixture with the pre-cleaned partial flow having a high temperature, the temperature drop of the exhaust gas is small, this also adds to an efficient cleaning of the exhaust gas in the downstream part 8B of the catalytic converter 8.
  • the present invention relates to a method for catalytically cleaning the exhaust gas of an internal combustion engine and an exhaust gas system wherein a multi-staged cleaning of exhaust gas takes place by means of that the total flow of exhaust gas is sub-divided into a plurality of partial flows of exhaust gas, at least in two flows of exhaust gas, fed through a catalytic converter means in successively varying amounts of volume through different parts of the catalytic converter means.
  • cleaning activity of the catalytic converter means can be improved and more even heat distribution across the catalytic converter means can be obtained and a small sized construction of a muffler of the exhaust gas system is possible.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Silencers (AREA)

Claims (19)

  1. Verfahren zur katalytischen Reinigung eines Abgases einer Verbrennungskraftmaschine (2), die einen Katalysatorkörper (8), der in einem Abgastopf (5) eines Abgassystems der Maschine angeordnet ist, aufweist, dadurch gekennzeichnet, daß ein Gesamtstrom des Abgases in eine Vielzahl von Abgasteilströmen aufgeteilt wird, ein Abgasteilstrom durch einen ersten Zweig (8A) des Katalysatorkörpers (8) geführt wird und dann der wiederzusammengeführte Abgasgesamtstrom durch einen zweiten Zweig (8B) des Katalysatorkörpers (8) geführt wird.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß eine Vorreinigung eines Teils des Abgasgesamtstromes in den ersten Zweig des Katalysators durchgeführt wird, und daß der vorgereinigte Teil des Abgases dann wieder mit dem Rest des Abgasgesamtstromes zusammengeführt wird, um durch den zweiten Zweig des in dem Abgastopf (5) angeordneten Katalysatorkörpers geführt zu werden.
  3. Verfahren nach zumindest einem der vorhergehenden Ansprüche 1 oder 2, dadurch gekennzeichnet, daß ein Teil des Abgasgesamtstromes durch einen Abschnitt eines einzigen Katalysatorkörpers (8) geführt wird, wobei sich der Abschnitt in einen Endabschnitt (4b) eines Abgasrohres (4), das sich in den Abgastopf (5) erstreckt, hineinragt.
  4. Verfahren nach zumindest einem der vorhergehenden Ansprüche 1 bis 3, dadurch gekennzeichnet, daß ein Teil des Abgasgesamtstromes durch einen Abschnitt (8A) eines einzigen Katalysatorkörpers (8) geführt wird, wobei der Abschnitt (8A) einen Teil eines Abgasnebenpfades bildet, der von einem Endabschnitt (4b) des Abgasrohres (4) abzweigt.
  5. Verfahren nach zumindest einem der vorhergehenden Ansprüche 1 bis 4, dadurch gekennzeichnet, daß der Hauptteil des Abgasgesamtstromes ohne Vorreinigung zu einem am weitesten hinten liegenden Endabschnitt des Abgastopfes (5) geführt wird, daß der Abgasstrom umgekehrt wird zu einer zentralen Expansionskammer (C), in der die Wiederzusammenführung des Hauptabgasstromes und des vorgereinigten Teils des Abgases stattfindet und der zusammengeführte Gesamtabgasstrom durch den Teil (8B) des einzigen Katalysatorkörpers (8) geführt wird, der nicht der Durchströmung des Teils des Abgasgesamtstromes zur Durchführung der Vorreinigung dieses Teils ausgesetzt war.
  6. Verfahren nach zumindest einem der vorhergehenden Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die Abgasströmung innerhalb des Abgastopfes (5) entlang der Längsachse desselben umgekehrt wird von einer am weiteesten hinten liegenden Expansionskammer (D) zu einer vorderen Expansionskammer (A), um von dem Katalysatorkörper (8) behandelt zu werden, und dann zu dem Hinterseite des Abgastopfes (5) durch eine trennende Strömungsführungsvorrichtung (13) zurückgeführt und von der Hinterseite des Abgastopfes (5) abgeführt wird.
  7. Abgassystem einer Verbrennungskraftmaschine (2) mit einem Abgasrohr (4), das sich in einen Abgastopf (5) erstreckt, der einen Katalysatorkörper (8) aufnimmt und eine Vielzahl von Abgasaufnahme-Expansionskammern (A bis D) aufweist, dadurch gekennzeichnet, daß der Katalysatorkörper (8) einen ersten Zweigdurchgang (8A) aufweist, durch den ein Teilstrom eines zugeführten Abgasgesamtstromes geführt wird, und einen zweiten Zweigdurchgang (88), durch den der wieder zusammengeführte Abgasgesamtstrom geführt wird.
  8. Abgassystem nach Anspruch 7, dadurch gekennzeichnet, daß die Katalysatorvorrichtung einen einzigen, in dem Abgastopf angeordneten Katalysatorkörper (8) aufweist.
  9. Abgassystem nach Anspruch 7 oder 8, dadurch gekennzeichnet, daß der Katalysatorkörper (8) teilweise in einen Endabschnitt (4b) des Abgasrohres (4) hineinragt.
  10. Abgassystem nach einem der Ansprüche 7 oder 8, dadurch gekennzeichnet, daß der Katalysatorkörper (8) seitlich des Abgasrohres (4) angeordnet ist und daß eine Abgasführungsvorrichtung (21) vorgesehen ist, die von dem Abgasrohr (4) stromauf des Katalysatorkörpers (8) abzweigt und mit dem ersten Zweigdurchgang (8A) des Katalysatorkörpers (8) verbunden ist, wobei der erste Zweigdurchgang (8A) einen stromab angeordneten Abschnitt der Abgasführungsvorrichtung (21) bildet.
  11. Abgassystem nach zumindest einem der vorhergehenden Ansprüche 7 bis 10, dadurch gekennzeichnet, daß der Abgastopf (5) eine Vielzahl von Expansionskammern (A bis D) aufweist, die durch Aussparungen aufweisende Prallplatten (9,10,11) getrennt sind, wobei die Expansionskammern (A bis D) entlang der Längsachse des Abgastopfes (5) aufeinanderfolgend angeordnet sind.
  12. Abgassystem nach Anspruch 11, dadurch gekennzeichnet, daß die Prallpaltten (9,10,11) Querwände des Abgastopfes (5) bilden.
  13. Abgassystem nach zumindest einem der vorhergehenden Ansprüche 7 bis 12, dadurch gekennzeichnet, daß der Katalysatorkörper (8) so angeordnet ist, um eine stromauf angeordnete Expansionskammer (C) mit einer weiter stromab angeordneten Expansionskammer (A) zu verbinden.
  14. Abgassystem nach Anspruch 13, dadurch gekennzeichnet, daß der Katalysatorkörper (8) so angeordnet ist, um eine stromab angeordnete Expansionskammer (B) zu überbrücken, von der sich ein Abgasausstoßrohr (18) aus dem Abgastopf (5) heraus erstreckt.
  15. Abgassystem nach zumindest einem der vorhergehenden Ansprüche 7 bis 14, dadurch gekennzeichnet, daß ein Auslaß (4b) des Abgasrohres (4) sich in die hinterste Expansionskammer (D) erstreckt, von der ein Zurückströmen des Abgases nach vorne bewirkt wird durch eine mittlere Expansionskammer (C), den Katalysatorkörper (8) und eine vordere Expansionskammer (A) zu der stromab angeordneten Expansionskammer (B).
  16. Abgassystem nach Anspruch 12, dadurch gekennzeichnet, daß der Katalysatorkörper (8) durch die Querwände (9,10) gelagert ist, die die stromab angeordnete Expansionskammer (B) bilden, um sich durch eine Ausnehmung des Abgasrohres (4) zu erstrecken, um teilweise in das Innere dieses Abgasrohres (4) hineinzuragen zur Ermöglichung eines Abgasteilstromes durch den vorragenden Abschnitt (8A) des Katalysatorkörpers (8) von einer stromauf gelegenen Eingangsseite zu einer stromab gelegenen Ausgangsseite desselben.
  17. Abgassystem nach zumindest einem der vorhergehenden Ansprüche 7 bis 16, dadurch gekennzeichnet, daß der Teil (8A) des Katalysatorkörpers (8), der einen vorreinigenden ersten Zweigdurchgang des Katalysatorkörpers (8) bildet, eine Teilfläche aufweist, die gleich oder kleiner als zwei Drittel des Querschnittes des gesamten Katalysatorkörpers (8) ist und der Teil des Abgases, der durch den ersten Zweigdurchgang (8A) ders Katalysatorkörpers (8) strömt, maximal zwei Drittel der Abgasgesamtmenge beträgt, die durch das Abgasrohr (4) strömt.
  18. Abgassystem nach zumindest einem der vorhergehenden Ansprüche 7 bis 17, dadurch gekennzeichnet, daß der Katalysatorkörper (8) einen wabenförmigen Grundkörper mit auf seiner aktiven Oberfläche abgelagerten katalytischen Substanzen aufweist.
  19. Abgassystem nach zumindest einem der vorhergehenden Ansprüche 7 bis 18, dadurch gekennzeichnet, daß der Katalysatorkörpers (8) eine Wickelstruktur besitzt, für die eine flach gekrümmte Folie (8a) und eine gewellte, gekrümmte Folie (8b) übereinanderliegend spiralartig aufgewickelt werden, wobei die Folien (8a,8b) miteinander durch Löten verbunden sind.
EP93105250A 1992-03-30 1993-03-30 Verfahren zur katalytischen Reinigung der Abgase einer Brennkraftmaschine und Abgasvorrichtung Expired - Lifetime EP0563882B1 (de)

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DE19611133A1 (de) * 1996-03-21 1997-09-25 Eberspaecher J Schalldämpfer-Anordnung
FR2775498B1 (fr) * 1998-02-27 2000-04-07 Inst Francais Du Petrole Procede de traitement des gaz d'echappement d'un moteur a combustion interne et ligne d'echappement associee
DE19834822A1 (de) * 1998-08-01 2000-02-03 Stihl Maschf Andreas Abgasschalldämpfer mit einem Katalysator
KR20020034476A (ko) * 2000-11-02 2002-05-09 김영철 자동차용 소음기
JP4533802B2 (ja) * 2005-05-31 2010-09-01 東京濾器株式会社 ディーゼルエンジン用の排ガス浄化マフラー
JP2007185894A (ja) * 2006-01-13 2007-07-26 Komatsu Zenoah Co チェーンソー
CN101482045A (zh) * 2009-02-03 2009-07-15 重庆隆鑫机车有限公司 全地形车消声器
JP5893926B2 (ja) * 2012-01-12 2016-03-23 富士重工業株式会社 触媒内蔵マフラ

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EP0355489A1 (de) * 1988-08-26 1990-02-28 Bayerische Motoren Werke Aktiengesellschaft, Patentabteilung AJ-3 Verzweigte Abgasleitung einer Brennkraftmaschine

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JPS57198315U (de) * 1981-06-12 1982-12-16
DE4002774A1 (de) * 1990-01-31 1991-08-01 Boysen Friedrich Gmbh Co Kg Auspuff fuer verbrennungsmotoren mit katalysator

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0355489A1 (de) * 1988-08-26 1990-02-28 Bayerische Motoren Werke Aktiengesellschaft, Patentabteilung AJ-3 Verzweigte Abgasleitung einer Brennkraftmaschine

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DE69313695D1 (de) 1997-10-16
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EP0563882A1 (de) 1993-10-06
JPH05280329A (ja) 1993-10-26

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