DE2318480A1 - METHOD OF OPERATING COMBUSTION MACHINES AND COMBUSTION MACHINE FOR CARRYING OUT THE METHOD - Google Patents

Description

W / Vh-2938 04/10/73

General Motors Corporation, Detroit, Mich., V.St.A. "

Method for operating internal combustion engines and internal combustion engine for carrying out the method

The invention relates to a method for operating internal combustion engines whose fuel gases from the Combustion chambers via an exhaust gas box and an exhaust gas converter, which contains a catalyst bed for reaction with the exhaust gases, can be derived in order to then exit via an exhaust pipe.

It has been recognized that the proportion of hydrocarbons, carbon monoxide and nitrogen oxides in the exhaust gases can be kept at a low level by internal combustion engines when the exhaust gases are initially in a reducing

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Atmosphere are passed through a catalyst bed to nitrogen oxides to dissociate and then through another catalyst bed in an oxidizing atmosphere to produce hydrocarbons and to oxidize carbon monoxide. However, this process is not effective until the catalyst beds are at an elevated temperature are brought. For this purpose, the catalyst beds are housed in a countercurrent oil converter, which is closely coupled to the exhaust box of the internal combustion engine to be heated by the exhaust gases. With a ■ V-type internal combustion engine with two outlet boxes become two converters required, which are each connected to one of the outlet boxes.

It was also found that the time required to heat up the catalyst beds was further reduced can be if air is introduced into the area of the combustion chamber outlet openings instead of between the To supply catalyst beds while the catalyst beds are being heated up. This supplied air supports one Oxidation of the fuel gases and the resulting heat support the heating of the catalyst beds. Ifachdem the catalyst beds have reached the required temperature, this air supply to the Auslas soffmangen of the combustion chambers is partially or completely cordoned off to get into your first catalyst bed to create a reducing atmosphere, and that's the first To add air to the exhaust gases leaving the catalyst bed in order to be in the

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second catalyst bed to create an oxidizing atmosphere.

Furthermore, it has been found that a better control of the composition of the exhaust gases by means of a catalytic Converter can be reached when a part of the intake box "is heated up quickly during the run time. This favors the evaporation of the fuel in the mixture supplied by the carburetor and allows a poorer one to be set Mixture. The faster the! ^ Suction box is heated up, the more rather, the throttle of the carburetor can be opened to set a lean mixture. With the usual training Such heating devices, however, the exhaust gases from the one outlet box via a heat exchange area below of the suction box is routed to the other outlet box so that the suction box does not heat up as quickly as required would have happened. With such a design, in a V-type internal combustion engine with two outlet boxes, each of which a catalytic converter is assigned to the one converter during the Warailaufzeit no exhaust gases, so this accordingly later heated and thus effective.

The invention is based on the object of further developing the method mentioned at the beginning in such a way that the Advantages of the above-mentioned known methods are combined, but their disadvantages are avoided. As an additional task is exposed to the converter against high temperatures

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that are created by the exothermic reactions in the reduction: and oxidation that takes place in them. So far has been for this purpose the converter is bypassed at high temperatures without, however, a control of the exhaust gas composition took place during this time. The additional task is to protect the converter against high temperatures while maintaining effective control of exhaust gas composition.

The object set is thereby achieved according to the invention solved that in an operating state of the internal combustion engine this works in converter mode, in which the exhaust gases from the Outlet box are passed through the catalyst bed to the exhaust pipe, and in another operating state of the internal combustion engine in reaction mode, in which the exhaust gases flow directly from the outlet box to the exhaust pipe and in the outlet box an oxidation zone is formed in which the hydrocarbons and carbon monoxides contained in the exhaust gases are burned will.

In such a method for internal combustion engines, in which the converter has a reducing part with a Catalyst bed for dissociating nitrogen oxides contained in the exhaust gases in a reducing atmosphere and a oxidizing part for oxidizing hydrocarbons and carbon monoxide contained in the exhaust gases is provided,

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that in converter operation the exhaust gases from the outlet box one after the other flow through the reducing part and the oxidizing part of the converter before they are directed to the exhaust pipe, wherein a reducing atmosphere is set in the reducing part and into the atmosphere leaving the reducing part Exhaust gases are supplied with air to form an oxidizing atmosphere to oxidize the hydrocarbons and carbon monoxide will.

According to a further feature of the invention it is provided that the internal combustion engine during low temperature conditions works in warm-up mode, in which the exhaust gases from the outlet box are routed through the converter to the exhaust pipe and air is introduced into the exhaust gases close downstream of the outlet openings of the combustion chambers, which causes the oxidation the hydrocarbons and carbon monoxide contained in the exhaust gases and the heat generated thereby supports the converter heats. In such a method for internal combustion engines with mixture supply via the intake system, it is useful to if in the warm-up operation exhaust gases in the heat exchange the mixture to support the evaporation of the fuel in the mixture.

Further useful procedural steps result in | from the other subclaims. I.

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A very rapid heating of the intake box is provided by an effective heat exchange area, the is heated by the exhaust gases from all combustion chambers. In the case of a V-type internal combustion engine with two outlet boxes, there are two catalytic ones Converters are provided, which are directly connected to one of the outlet boxes in order to be heated more quickly. During the warm-up period, the exhaust gases are routed through the heat exchange area for the intake box to the converters. The time in the area of the combustion chamber outlet openings during the warm-up period Air supplied supports the oxidation of hydrocarbons and carbon monoxide in the exhaust gases and increases also the exhaust gas temperature, so that a faster heating the intake box and the converter enters.

When the converter is at an elevated temperature, air is fed into the area of the combustion chamber outlet openings in order to cause the oxidation of hydrocarbons and carbon monoxide in the outlet boxes, so that these act to purify the exhaust gases, whereupon the exhaust gases treated in this way are fed directly to the exhaust pipe so that the converters i

are protected against the high exhaust gas temperatures. :

. Such operational management is also advantageous

^; ■ i used at high engine speeds, which at!

Travel of the powered vehicle may occur. There are j then get low levels for the harmful components of the

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Exhaust gases during operation at high speeds and since the converter under these operating conditions for a longer time from the exhaust gases are not flowed through, a longer service life can be expected.

In summary, it can be stated that according to the invention Three operational controls are provided: During the warm-up operation, air is drawn into the area of the combustion chamber outlet openings fed to cause an oxidation of the unburned exhaust gas components, the exhaust gases after the heating of the Suction box are passed through the converter in order to warm it up. When the converter is in operation, the exhaust gases are sent to the converters fed and pass through the reducing part to reduce the content of nitrogen oxides, after which by feeding of air in the exhaust gases leaving the reducing part in the created oxidizing atmosphere a reduction of the Content of hydrocarbons and carbon monoxide is achieved. During reaction operation, air is in the area of the combustion chamber outlet openings introduced to create oxidizing conditions in the outlet box and the exhaust gases are bypassed the converter is diverted to protect the catalyst beds. The invention also relates to an internal combustion engine for carrying out the method according to the invention. This is characterized by what is specified in the subclaims

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231

Characteristics.

Although the invention in connection with ai * Internal combustion engine is described, it is.bei others engine types applicable, for example in-line burners - * prime movers or rotary piston machines,

In the drawing is an embodiment of an internal combustion engine according to the invention for performing the inventive method shown * In deir drawing demonstrate

Figv 1 is a side view of an internal combustion engine with an intake box with an attached exhaust gas converter,
Fig. 2 is a plan view of Fig. I mi-fc dismantled

Carburetor and air filters,

FIG. 3 shows a section along the line 3- * 3 in FIG. 2 and Flg. 4 shows a section drawn in section; the end-

Fig. 1 on a larger scale.

The eight-cylinder V-type internal combustion engine 10 has combustion ^ spaces 12, which are arranged in cylinder blocks 14 and 16. An intake box 18 is located between the rows of cylinders 14 and 16 provided on which a carburetor 20 and an air filter 22 are placed are.

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The intake box 18 has several riser pipes 24 for supplying mixture from the carburetor 20 to a common one Suction chamber 26 (Figure 3), from which several openings 28 to the branch off individual suction channels 30, which lead to inlet openings of the combustion chambers 12 (FIG. 2).

The intake box 18 contains two exhaust gas transverse channels 34 and 36 below the suction chamber 26, the front transverse channel 34 a: Inlet opening 38 for receiving the exhaust gases from the combustion chambers of the right cylinder bank 16 and the rear Transverse channel 36 has an inlet opening 40 for receiving the exhaust gases the combustion chambers of the left cylinder bank 14.

. Outlet openings 42 of combustion chambers 12 lead to exhaust gas ducts 44 which are connected to left and right outlet boxes 46, respectively or 48 are connected.

An air pump 50 supplies air via distributor pipes 52 to metering pipes 54, which are sealed in the outlet channels 44 Open downstream of the outlet openings 42 (FIG. 3) so that air is mixed with the exiting fuel gases.

As shown in Fig. 4, each outlet box includes an outlet chamber 56 to which the exhaust gases from the exhaust ducts 44 flow in via channels 58. At the bottom of the outlet chamber 56 there is a valve 62 which controls the path of the exhaust gases and, in the position shown, the exhaust gases from ducts 58

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through the outlet chamber 56 to the central channel 58 direct. The exhaust gases from the front and rear combustion chambers 12 of the right cylinder bank 16 are discharged from the outlet openings 42 of the middle combustion chambers 12 of the right cylinder bank 16 and together with these to the inlet 38 guided and forced through the front exhaust gas transverse channel 34. In the same way, the exhaust gases from the front and rear combustion chambers 12 of the left cylinder bank 14 at the outlet openings 42 of the middle combustion chambers 12 of the left cylinder bank passed and with these together over the Inlet 40 passed through the rear, exhaust transverse channel 36.

Air supplied through the pump 50 and the distributor pipes 52 as well as the metering pipes 54 causes oxidation of Hydrocarbons and carbon monoxide contained in the exhaust gases. The heat generated in this reaction is via a Transferring heat-dissipating surface 64 (FIG. 2) between the exhaust gas transverse channels 34 and 36 and the suction chamber 26 and causes a Evaporation of the fuel of the mixture allocated in the inlet box 18 from the carburetor: 20. Appropriately there is the heat transferring Surface 64 made of sheet metal or metal casting: which is attached there or formed as part of the casting. The surface can be provided with ribs to improve the heat transfer.

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The exhaust gas transverse channel 34 has an outlet opening 66 to a pipe 68 and the exhaust gas transverse channel 36 has an outlet opening 70 to a pipe 72. A valve housing 74 contains a valve 76 (Fig. 4) located at the end of the pipe 72 · A The same valve housing with valve can also be provided at the end of the tube 63. If necessary, the two valves 62 and 76 can also be combined into one unit »

On each side of the internal combustion engine 10, a channel 78 extends from the pipe 72 or 68 into a converter 82 ₁ , its mouth 80 being located in a lower chamber 81 of the converter. Exhaust gases exiting channel 78 flow upwards through two catalyst beds 84 and 86 and reach an upper chamber 88 and then through an outlet 90 to an exhaust pipe 92 supports the heating of the catalyst beds 84 and 86 and the flow through both catalyst beds parallel to one another ensures a simultaneous heating of both catalyst beds.

After a certain time, the valve 62 is moved from the illustrated closed position into the position 94 shown in dashed lines. The exhaust gases can then ^: through an opening 60 into the upper chamber 88 of the converter 82:

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enter above the Katlal3 ^ satorbettes 84, flow through this down to the lower chamber 81 and then the other catalyst bed 86 back up into the upper chamber 88, from which they reach the exhaust pipe 92 via the outlet 90. Additionally the valve 76 can be partially or completely closed. A valve 98 (FIGS. 1 and 4) can be partially or completely closed are to decrease or shut off the delivery of air from the pump 50 via the manifold 52 to in the Catalyst bed 84 to set a reducing atmosphere. A valve 100 in a line brought up from the pump 50 102 to the lower chamber 81 controls the air supply to the lower chamber 81.

If the carburetor 20 is set correctly, the positions flowing out of the combustion chambers 12 via the outlet openings 42 Fuel gases represent a reducing atmosphere and by partially or completely closing the valve 98 and thereby The exhaust gases reaching the catalyst bed 84 represent a corresponding reduction in the supply of air to the exhaust gas box represents a reducing atmosphere, so that in the catalyst bed 84 a dissociation of the nitrogen oxides contained in the exhaust gases he follows. If the exhaust gases enter the lower chamber 81 of the converter 82, air is fed in via the line 102, to set an oxidizing atmosphere. The exhaust fumes

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then up through catalyst bed 86 which causes oxidation of the hydrocarbons and carbon monoxide contained in contained in the exhaust gases. In certain circumstances, the catalyst bed 86 is not necessary to this oxidation process to effect.

From the above it follows that the internal combustion engine is extremely advantageous during the Warm-up is operated, wherein the intake box 18 is heated to support the evaporation of the fuel in the mixture, thereby enabling the setting of a lean mixture early and around the catalyst beds 84 and warm up so that the catalytic reactions start as soon as possible. At the same time there is an oxidizing in the exhaust gas box Set the atmosphere by which the hydrocarbons and carbon monoxide contained in the exhaust gases are oxidized Share v / is particularly high during the warm-up period. As soon as this is possible, the system will start up from warm-up mode Converter operation switched by both a dissociation of the nitrogen oxides and an oxidation of the hydrocarbons and from carbon monoxide.

Should excessive temperatures arise, the valve 62 can move from the position 94 to the position shown in dashed lines Position 104 (Fig. 4) shown in the lines, so that the exhaust gases then flow directly from the outlet

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kainmer 56 through the upper chamber 88 of the converter 82 to Pass outlet 90 and thus a flow of the exhaust gases through the catalyst beds 84 and 86 is prevented.

At the same time, the valve 98 can be opened so that the air pump «50 via the distributor pipes 52 and the feed pipes 54 air to the combustion chamber outlet openings

who delivers. In this way, the oxidation of the hydrocarbons and carbon monoxide contained in the exhaust gases continues within the outlet box 48 so that it acts as an exhaust gas reactor, while at the same time the catalyst beds 84 and 86 can cool down.

The valve 100 can remain open so that cooling air flows through the pipe 102 to the catalyst beds 84 and 86. However, it can also be expedient to close the valve 100, so that an oxidation of hydrocarbons and carbon monoxide remaining in the catalyst beds 84 and 86 does not enter.

Under certain operating conditions, for example when the vehicle equipped with the internal combustion engine is traveling at high speed, the proportion of nitrogen oxides in the exhaust gases is low _o It is then advisable to move the valve 62 to position 104 so that the exhaust gases do not reach the catalyst beds 84 and 86 flow through. This prevents overheating of the catalyst beds and conditionally

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an increase in the life of the catalysts as they are over the exhaust gases do not flow through for longer periods of time. The oxidation of the hydrocarbons contained in the exhaust gases and the carbon monoxide continues to occur in at this time the exhaust gas box 48, since the valve 98 is open, so that the pump 50 air to create an oxidizing atmosphere in Auslasskadsn 48 delivers.

The setting tools for the valves shown in Fig. 4 are not shown in more detail, since suitable facilities are the Experts are familiar. For example, vacuum motors can be used to operate the valves, the den The negative pressure supplied to the valves is regulated by magnetic control devices, which are excited by a sensing circuit v / earth. The sensing circuit responds, for example, to parameters of the operating state, for example to the temperature in one of the converters.

It is also not necessary to route the exhaust gases from the exhaust gas cross channels to the lower chambers of the converter? rather, this can also take place in the upper chambers of the converter above the reducing part, whereupon the throughflow the exhaust gases successively through the reducing and to-; finally the oxidizing part takes place. In this case, however, a different design of the valve 62 is required ^

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thus its protective effect against excessively high temperatures exercises. However, this is within the scope of professional ability.

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Claims (14)

231848Q 17 Fatent Claims (ΪΤ) Process for the operation of internal combustion engines, their combustion gases from the combustion chambers via an exhaust gas box and an exhaust gas converter, which has a catalyst bed for the reaction with the exhaust gases, are diverted in order to subsequently exit via an exhaust pipe, characterized in that that in an operating state of the internal combustion engine this works in converter mode in which the exhaust gases from the outlet box (48) through the catalyst bed (84, 86) to the exhaust pipe (92), and at another Operating state of the internal combustion engine in reaction mode, in which the exhaust gases flow directly from the outlet box to the exhaust pipe and an oxidation zone (54) is formed in the outlet box in which hydrocarbons and carbon monoxide contained in the exhaust gases are burned. 2. The method according to claim 1 ^ for internal combustion engines, in which the converter has a reducing part with a catalyst bed for dissociating from contained in the exhaust gases Nitrogen oxides in a reducing atmosphere and an oxidizing part for oxidizing those contained in the exhaust gases Contains hydrocarbons and carbon monoxide, which means that -18- 30984 670 790 231848Q shows that in converter operation the exhaust gases from the outlet box (48) successively the reducing part (84) and the oxidizing part Part (86) of the converter flow through before they are passed to the exhaust pipe (92), wherein in the reducing part a reducing atmosphere is set and in the exhaust gases leaving the reducing part air to form an oxidizing Atmosphere for oxidizing the hydrocarbon and carbon monoxide is supplied. 3. The method according to claim 1 or 2, characterized characterized in that the one operating condition of the internal combustion engine below a predetermined temperature and the other operating condition of the internal combustion engine operating temperatures ~ are above this predetermined temperature. 4. The method according to claim 1 or 2, characterized characterized in that the one operating condition of the internal combustion engine Speeds below a predetermined speed and the other operating condition of the internal combustion engine speeds are above this specified speed. 5. The method according to any one of claims 1 to 4, characterized in that the internal combustion engine during lower temperature conditions - works in warm-up mode, in which the exhaust gases from the outlet box (48) are directed through the converter (82) to the exhaust pipe (92), and into the exhaust gases close downstream of the outlet opening (42) of the combustion chambers (12) air -19- 309846/0790 (Feed pipes 54) is initiated, which oxidizes the hydrocarbons and carbon dioxide contained in the exhaust gases and the heat generated in this way heats the converter. 6. The method according to claim 5 for internal combustion engines with mixture supply via the intake system, characterized in that exhaust gases are exchanged during the warm-up operation (Area 64) heat the mixture to assist in evaporation of the fuel in the mixture. 7. The method according to claim 6, characterized in, that the heat exchange between the exhaust gases and the mixture in the intake system before the exhaust gases are fed to the Converter takes place. 8. The method according to any one of claims 1 to 7, characterized in that the combustion chambers (I2) during converter operation a richer mixture is fed in than in the reaction operation. 9. The method according to any one of claims 1 to 4, characterized in that air during reaction operation (Feed pipes 54) is fed close downstream of the outlet openings (42) of the combustion chambers (12) to form the oxidation zone. 10. internal combustion engine for carrying out the ^comparison: driving according to one of claims 1 to 9 with combustion chambers, a; the combustion gases from this receiving outlet box, one at -20- 309846/0790 this connected exhaust converter and. an exhaust gas pipe, characterized in that a catalyst bed (84, 86) for reaction with the exhaust gases is provided in the converter (82), and a first flow path from the outlet openings (42) of the combustion chambers (12) through the outlet box (48) to the Converter, through the catalyst bed of which is formed to the exhaust gas pipe (92), and a second flow path leads from the outlet openings of the combustion chambers via the outlet box directly to the exhaust gas pipe, and both flow paths optionally through a valve (62) which can be set between two positions (94 and 104) can be switched on. 11. Internal combustion engine according to claim 10, characterized in that the catalyst bed consists of a reducing Part (84) for dissociating nitrogen oxides in a reducing atmosphere and an oxidizing part (86) for oxidizing of hydrocarbons and carbon monoxide in an oxidizing atmosphere, and the valve (62) in its setting (94) for converter operation, the exhaust gases from the outlet box (48) to the converter, the reducing and oxidizing Partially flowing through the exhaust pipe (92), while in a second position (104) for reaction operation the exhaust gases flow via the outlet box directly to the exhaust pipe, that an air supply line (52) to the outlet box (49) -21- 309846/0790 Valve (98) which is closed during converter operation in this the formation of a reducing atmosphere and at Reaction operation open to an oxidizing atmosphere allows that between the reducing and the oxidizing Part of the converter an air supply (102) is provided and. contains an adjustable valve (lOO), and that the Flow path-determining valve (62) by temperature and speed-dependent devices depending on predetermined Levels can be actuated. 12. Internal combustion engine according to claim 11, characterized in that the valve (98) provided in the air supply line (52) to the outlet box (48) during reaction operation and Warm-up operation is adjustable in a position in which there is sufficient to form an oxidizing atmosphere in the outlet box Lets through air volume, while in a position for converter operation it limits the air flow to such an extent that no oxidizing atmosphere is created in the outlet box, and the valve a predetermined time after starting the internal combustion engine remains in the position for warm-up operation, so that in the warm-up operation, the oxidation of the hydrocarbons and carbon monoxide contained in the fuel gases in the outlet box heated exhaust gases flow through the converter and this heat up before the valve is moved to the position for converter operation. -22- j 309846/0790 13. Internal combustion engine according to one of claims 10 to 12 with mixture supply via the intake system, characterized characterized in that areas (64) which are in heat exchange with the intake duct (24) are provided which pass through from the outlet openings (42) of the combustion chambers (12) flowing fuel gases are heated, and these areas also with the converter (82) are connected (lines 72,76). 14. Internal combustion engine according to claim 13, characterized in that the valve (62) which determines the flow paths immediately after starting the internal combustion engine in one of the converter (82) and the exhaust pipe (92) from the outlet box (48) separating position can be moved in order to guide the exhaust gases into the area (64) which is in heat exchange and for a predetermined Time remains in this position before it is moved into its position corresponding to the converter operation. 309846/0790