DE2450994A1 - FOUR-STROKE COMBUSTION ENGINE - Google Patents

Description

Patent attorney D'pl. Inc ·. M. J. Huebner

QÜe <) Corr. Pie η / AiIg. O / ■ C η Ω ft /

LiiiCfau & r Str. 32 -Telejon 0031/232 * 1 ZHDU D 5ί 4

2 5. υ. 1974

Λ W 5 "

The invention "relates to a four-stroke combustion engine designed for. Everyone Cylinder an intake pipe with an intake port and an intake valve; and an exhaust pipe having an exhaust port and an exhaust valve having and with 'a device for supplying air and of Fuel in the intake line, and is provided with an ignition device for generating an ignition spark on a spark plug in the cylinder.

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Such an internal combustion engine can contain agents that produce only minimal amounts and concentrations of nitrogen oxides (NOx) · carbon monoxides (CO) and unburned hydrocarbons (HC). Dor Hotor is operated with a lean air / fuel mixture in low and high load conditions, which minimizes the emission of the above-mentioned impurities. The use of inajoren mixtures in conditions of stress is made possible by means and methods with which a suitable lower numerical value of the residue fraction is created, which is the ratio between the amount of gas residues remaining in the cylinder and the total amount of gas residues and those fresh in the cylinder flowing gases is defined. These means may include means to reduce the amount of time the intake and exhaust valve overlap or to open the engine throttle wider than normal and delay the ignition to reduce engine speed at low loads. Preferably means are provided to allow the fuel to flow is well atomized in the air / fuel mixture ", resulting in a uniform and homogeneous mixture. Some of these means can have devices with which a film of fuel adhering to the suction line wall is collected and returned to the air flow or atomized by heat.

The emission of pollutants as a result of the operation of internal combustion engines has become a matter of serious social unrest. Increasingly stringent restrictions on these air pollutants are being imposed and there is an urgent need for engines that comply with the new regulations. The best solution will be a way in which uses substantial parts of the existing "TgChnologie and tools advertising

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the can ' ^{un <} i which can be used for engines of the present construction without any radical changes being necessary. Lösun ^ sr ^ radical new designs and extreme changes in KotorerJConzeptionen and K _o nstruktionen entail are probably because of resistance to changes in buyers and the people dio establishing and maintenance of the new mechanisms eriernön nuts, wönigor effective. As a result, delays and poor performance can be expected if significant deviations from existing technologies are necessary.

It is an object of the invention to look for a solution to the problem dos To take care of the emission of impurities, in which an essential Part of the existing technology can be used and which at pre ■ Phrase ·. · In some or even most conventional. Internal combustion engines only makes relatively small changes and constructions necessary. Other conventional engines may require major * modifications, but which are clearly understandable and easy to use are. It can therefore be expected that this will have minimal resistance against their use.

It is an object of the invention to internal combustion engines and methods of operation to create these internal combustion engines with which the emission of Impurities, especially nitrogen oxides (NOx), are minimized.

According to the invention, this object is achieved in that the suction lines are connected to the exhaust via a valve, this valve controlling the flow of the exhaust gases into the intake lines. It turned out

S 0.9 8 S 0/0 β 3 7 bad original

245099A

represents that the recirculation of part of the exhaust gases in the combustion chamber has a beneficial effect on NOx emissions.

The tendency of an engine to misfire relates directly to the numeric value of a mathematical Ausruckes, the following "residue fraction is called ¹¹ The residue fraction is defined as follows.:

Amount of gas residue recovered from the previous Cycle remain in the combustion chamber

Residue breakage

Amount of air Amount of gas return (or air / stagnation from before fuel mixture), + forward cycle-; those for the next in the combustion cycle the combustion chamber remains in the combustion chamber

The term "amount" refers to the weight or volume that the same temperature and pressure is measured. As the numerical value of residue breakage decreases, so does the tendency of the engine to misfire.

To prevent the residue breakage in low load conditions Eu becomes large, the exhaust gas control valve is controlled by the pressure in the intake line controlled so that when the pressure in the intake line decreases, the flow through the exhaust gas control valve also decreases.

In this way it can be prevented that during the intake stroke the low pressure in one of the intake lines has a detrimental effect on the flow of fresh mixture to the cylinder.

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A simple construction can be obtained in that between the exhaust gas return line and the respective intake line a small one Nozzle or a one-way valve is arranged.

In order to prevent the ^l i? E ^m p ^era 't ^{ur of} the mixture in the suction lines from becoming too high, the. Exhaust gases passed through a cooler between the exhaust line and the exhaust gas control valve.

An advantageous control of the exhaust gas flow is achieved by that a first valve, controlled by the pressure in the suction line, between the exhaust line and a second valve, also controlled by the pressure in the suction line controlled valve is arranged, wherein the first valve controls the flow of exhaust gases to the second valve as a function of the intake pressure and the second valve regulates the flow of exhaust gases into the intake ducts regulated depending on the suction pressure.

A compact K _o natruktion of the engine is reached when an exhaust gas manifold is disposed in an intake manifold and when a plate is disposed between the intake manifold and the cylinder head, positioned on the leaf valves which the openings between the exhaust gas manifold and the Anaaugleitungen with short pressure peaks in the

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Ignore suction lines.

I.

This simple embodiment can be achieved in that the suction lines are provided with upwardly directed recesses for receiving the reed valves.

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The invention will now be illustrated by way of example Drawings are explained in more detail and shows: '«·

Figure 1 · ⁿ ei diagram showing the emission of certain impurities in relation to the air / fuel ratios with which an engine is operating,

Pig. 2 shows a plan view of an embodiment according to the invention of a motor, some parts being omitted for reasons of simplification,

Figure 3 is a partial cross-section along line 3-3 of Pig. 2, 4 shows a plan view of a further embodiment according to the invention an engine,

Fig. 5 shows a cross-section along the line 5-5 of the Pig. 4, Figures 6, 7, 8 and 9 are thematic cross-sections through parts of the Pig. 2 and FIG. 10 is a Ausführungsfora a compensating line in an intake manifold.

Since the diagram shown in Fig. 1 shows in a generalized and non- dimensional form the emission of impurities. Dia are plotted on the ordinate in relation to the air / fuel ratio, which is plotted on the abscissa. This diagram is generally valid for all internal combustion engines. In addition to the contaminants CO, HC and NOx, the exhaust gases also contain the correct gases, carbon dioxide (CO2) and oxygen (Og ) , as can be seen from the diagram.

In Fig. \ I "t also shown that when using magereron-Ge mitohen stoöohiometrische than the mixture (approx. 15 for gasoline) in a motor, as the ejection of the impurities CO and HC in comparison

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zuv using a rich mixture decreases rapidly. The same applies to the emission of nitrogen oxides ^ if mixtures with a ratio of more than 16 are used. It is therefore a significant advantage to drive an engine with an air / fuel mixture whose air / fuel ratio is leaner than the stoechiorometric ratio and which is preferably in the range between approximately 16 and 20 in order to minimize the emission of contaminants.

An embodiment of the invention is shown in FIGS. Viie can be seen from the figures, contains a four-stroke internal combustion engine four combustion chambers 11a, 11b, 11c and 11d. The term "cylinder" is sometimes used synonymously with the expression "combustion chamber". The engine 10 is provided with a throttle valve 30a, 30b, 30c and 30d and with a carburetor 20a, 20b, 20c and 20d for one combustion chamber each. Individual Suction lines 12a, 12b, 12c and 12d are each connected to one of the Inlet openings 15a, 15b, 15c and 15d of the combustion chamber 11a, 11b, 11c and 1ld connected. Set up suction lines 12a, 12b, 12c and 12d an embodiment of the "injection means, which serve to feed the mixture into the combustion chamber.

Exhaust lines 14a, 14b, 14c and 14d are connected to the outlet openings 16a, 16b, 16c and I6d of the combustion chambers 11a, 11b, 11c and 11d and absorb the exhaust gases. The exhaust pipes 14a, 14b, 14c and 14d and an exhaust system P, which removes the exhaust gases from the individual pipes collects, represents an embodiment of the "exhaust means", which to ' Discharge of the used gases from the combustion chambers 11a, 11b, 11c and 11d serve.

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AuspuffgasrlickfUhrlinien 13a, 13b, 15o, and 13d are with the intake lines 12a, 12b, 12c and 12d connected. The lines 13a to 13d are also connected to an exhaust gas recirculation valve V. One Vacuum line 12e (Figures 2 and 3) connects the opening 12f in the Suction line 12d and the opening 12g in the control valve V. The suction lines 12a, 12b and 12d are not connected to the opening 12g. The exhaust gas return lines 13a, 13b, 13c, and 13d are used when the NOx content through the recirculation of part of the exhaust gases into the intake Air / fuel mixture is controlled.

Figure 3 shows, in detailed form, parts of Figure 2 and specifically the parts that are directly in communication with the combustion chamber 11b. The other cylinders 11a, 11c and 11d and related parts are identical to FIG. 2, so that they are not described individually.

As can be seen from Fig. 3, the suction port 15b is from a suction valve seat 18 surrounded, while the exhaust valve opening 16b of a Exhaust valve seat 18a is surrounded. Am intake valve 21 and exhaust valve 22 are slidably mounted in the cylinder head and are designed in such a way that ' that when> there is a movement against the respective valve seat, the respective Close the opening and release the respective opening when moving away from the respective valve seat. Cams 81a and 82a are on the associated camshafts 81 and 82 and are used to open the valve openings 15b and 16b, the valves 21 and 22 being spring-loaded are so that the valve openings 15b and 16b remain closed when the cams do not hold the respective valves 21 and 22 open. The same

Intake and exhaust valves and seats, cams and camshafts and

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Return springs are also provided for the other combustion chambers.

The cylinder head H of the combustion chamber 11b is together with a Cooling jacket C shown. This cooling jacket C only shields the exhaust line Hb adjoining the exhaust openings i6b and the combustion chamber 11b * himself off. A section 17, which extends' from the inlet valve seat 18 upwards extends into the suction pipe 12b is not cooled by the cooling jacket C. Instead, this section 17 is allowed to be separated from the combustion chamber 11b ' is heated, for reasons that will be described below. This Section 17 can even be insulated from the outside or sheathed with hot material in order to maintain the increased temperature.

This section 17 preferably extends at least over a distance of 60 "to 70mm from the intake valve seat 15b up into the intake line 12b The section 17 is delimited by the inner wall 19 of the intake line 12b, the wall being thermally connected to the cylinder head K, that is, the inner wall 19 of the intake line 12b is heated by heat from the combustion chamber 11b the inner wall 19 of the section 17, it being undesirable for this section to be cooled by a coolant such as a cooling jacket C. Any coolant should be kept sufficiently far away from the section .17 ... so that the inner wall 19 as a result of the The heat supplied to the cylinder 11b can reach the necessary temperature Inderkopf H shown above the suction port 1 5b. Ia flüesigkoitsgakühltea engineea should aioh the cooling openingoa on theeaa side of the cylinder head aratreolcta, although as aioht necessary let

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that this region is cooled. Sa is a sufficiently thick material layer present between the part C1 of the cooling jacket 0 and the inner wall 19, that the inner wall 19 can heat up sufficiently, although the part CI of the cooling jacket C is present. The warm section 17 is a Embodiment of atomizing means to the on the inner wall 19 to atomize the suction pipe 12b adhering fuel.

In Fig. 2, an ignition distributor 23 is shown schematically. Conventional Condenser, breaker points, breaker cam and breaker shaft are used to create a spark ^ with which the equipment in the combustion chamber is ignited.

_{The exhaust gas recirculation valve V contains a K Q} lben 200 loaded by a spring 201, which with. a membrane 202 is connected, which is attached to the wall of a housing 203. The housing 203 contains a ventilated chamber 204 and a vacuum chamber 205. The spring 201 lifts the piston 200 into the position shown in FIGS. 4 and 8 with solid lines. As the vacuum in the vacuum chamber 204 increases, the piston 200 is moved downward. When the piston 200 has moved a sufficiently large distance downwards (see Fig. 9), it reduces or prevents the flow of exhaust gases from the inlet opening 206, from where the gas is otherwise to four outlet openings 207 for recirculation into the exhaust gas return lines 13a, 13b , 13c and 13d would be distributed. It follows that the amount of recirculated exhaust gas is a function of the size of the vacuum in the suction line 12b.

The principal advantage of using a throttle valve for each combustion chamber is that the pressure in one suction line is not reduced by the pressure in another suction line. For engines where one

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Intake line and a throttle valve a reciprocal number of combustion chambers supplied, the low pressure in a combustion chamber during the intake stroke

adversely affect the pressure at the inlet opening of the other combustion chambers influence. The use of one throttle valve per combustion chamber allows a separate intake condition to be set in each combustion chamber. Because the return lines 13a "his'; 3d Tie off all suction lines 12a to 12d, there is a tendency to a Pressure equalization in the suction lines 12a to 12d, by some of the Values that would otherwise be reduced through the use of a throttle valve would be achievable per combustion chamber.

In order to avoid this negative result, release agents are included in the jowoiligejr Return lines 13a to 13d provided, as can be seen from Figure .6, included these release agent shut-off valves 208, as an example are shut-off valves. 208, which include a flexible sheet 208 attached to the housing wall with a fastener 208b, each Sheet 208a closes the respective return line, unless a there is sufficient pressure difference through which. it is lifted off. One of the valves 208 of the suction line 12c is shown in the raised state when there is a sufficient pressure difference. If from valve V a If there is sufficient pressure, all valves 208 can be opened at once be. But if there is a sufficiently large, negative pressure in the line from valve V, possibly due to a high vacuum in one of the suction lines 12a to I2d (i2c in FIG. 6), are the other valves 208 closed, as shown in Figure 6 '. '·' "

Sometimes it is with engines-which have a throttle and a carburetor for each cylinder have quite beneficial when the intake lines are at

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High stress conditions are interrelated. If this connection is present, it is expedient to use the embodiment shown in FIG to use, in which the release agent contains nozzles 209, the bore on the one hand is small enough to reduce the gas flow in response to short pressure peaks and on the other hand is large enough to allow a gradual adjustment to allow pressure changes in the suction lines. By using such release agents during the idle state where the pressure is relatively low in the suction line, the pressure in one suction line is essentially not influenced by the pressure in another suction line, while under high load conditions the line that connects the suction lines with one another has a balancing effect on the pressure differences in the Exercises suction lines, this line also used to recirculate exhaust gases can be used.

In each combustion chamber, a piston 150 is arranged to be movable back and forth, The piston 150 rotates a crankshaft via a conventional crank pin and about connecting rod and crank parts, not shown.

Each carburetor 20a to 20d contains a high load circuit 50, a low load circuit 60 and event circle 70. The circles 50 and 60 lead a lean one Mixture with the correct ratio to the respective combustion chamber. The start circuit 70 also carries a lean air / fuel smell respective combustion chamber too, but the miso ratio can make a difference Have a smaller numerical value than the mix ratio at circles 50 and 60, so that when the engine slows down, the combined Mixture of the starting circuit and the low-load circuit 60 is approximately a stereochiometric Ratio corresponds. If only one to start the engine 10

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Air / fuel mixture is used by starting circuit 70, this is it lean (about 14: 1). When the mixture is combined with air that has a Throttle flows, the mixture becomes richer, so the resulting Mixture is suitable. The throttle valves 30a to 3Od (of which the throttle valve 30b is shown as an example), contain a throttle valve stem 31, which is rotatably mounted in the wall of the intake line is. The valve also contains a disk 32 attached to the stem 31, which acts as a throttle valve when the stem 31 rotates. A throttle arm 32a is attached to the stem 31 and to the carburetor, not shown. By Turning the arm 32a rotates the shaft 31 and adjusts the position of the Throttle disk 32 in the intake pipe to vary the cross-section in the intake pipe, which is open to the flow of liquid.

The section 17 of the suction line, which is adjacent to the suction valve seat, forms an atomizing agent. The inner wall 19 in this section has an elevated temperature, which should be kept between approximately 90 ° C. and 135 ° C. In flüssigkeitsgekUhlten motors optimum results are obtained because a Treibstoffilm evaporated at this Temeperatur at about 110 ⁰ C. Again, the temperature should not be so high that the entire mixture is heated, as this would be a disadvantage. Wall temperatures between approximately 90 C and 135 C seem to prevent this disadvantage. Each of the two atomizing means (the warm wall 19 and the groove.) Can advantageously be used alone. The use of both nebulizers together is even more advantageous.

The term "atomization" only refers to the passage ^{1 of} the liquid fuel into the air / fuel mixture and does not necessarily mean

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that the fuel is converted into a gas. In fact, the majority of the fuel is in small Tröpchen mixed, but due to the lower boiling point of the fuel are surrounded by the Teil.auch · Fuel Gas ^N. The term "atomization" is used in a broad sense for the removal of the liquid from the surface and its introduction into the stream of equipment.

When using an aluminum cylinder with a bore of around 70 to 90mm is, an axial length of section 17 is from about 60 to. 70 mm makes sense. The material thickness of the cylinder head adjacent to the intake pipe should be around 13 to 15mm. The wall thickness in section 17 should not be less than 6mm. Attention is drawn to the fact that the Cylinder head thickness with conventional cylinders only about 9mm and the wall thickness the suction line is only about 4mm. The greater material thickness, especially in the combustion chamber dome in this invention, ensures good conduction of heat into section 17 and shields this section against any cooling jacket that may be used.

The embodiment shown in FIGS. 2 and 4 with the heated wall works without insulation or sheathing in the desired temperature range. However, this section can also be insulated or provided with a heating jacket ¹ UnCl by heiaae exhaust gases, if this is necessary.

HC contamination can be caused by the use of a thermal reactor 40, which absorbs the exhaust gas flowing out of the outlet openings and keeps it at an elevated temperature, so that the HC through the

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oxygen remaining in the exhaust gas is oxidized. Such a reactor 40 forms part of the exhaust media. A useful thermal reactor 40 is shown in FIGS. The reactor 40 includes an outer housing 41 and a housing 42 lying between this and the exhaust line 14. An intermediate space 43 lies between the two housings 41 and 42. This Space 43 can be filled with a good insulating material or simply with air, which also serves as insulation. This gap 43 and whatever is in it serves as an insulating means to keep the reactor hot by retaining its heat.

To prevent the formation of NOx, the exhaust gases are passed through a Opening 44 (see Pig. 3) withdrawn from the reactor and through a Cooler 45, an exhaust gas control valve 46 and finally passed through a line 44b to the exhaust gas recirculation valve V. A conventional exhaust gas control valve 46 includes a diaphragm actuated piston 46b, the movement of which is created by a vacuum in line 12e above diaphragm 46a will. When the suction pressure is correct, the valve 46 is opened, whereby a part of the exhaust gases through the line 44b into the valve V and from there into the suction line is returned.

The embodiment according to FIGS. 4 and 5 will now be described below. The principal difference between the embodiment according to the figures 2 and 3 and the embodiment of Figures 4 and 5 is that only one throttle valve to control the air flow for a plurality of combustion chambers is provided, while in Figures 2 and 3 there is a throttle valve for each combustion chamber.

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In Figures 4 and 5, a four-stroke combustion rotor 100 is shown, the has four combustion chambers 111a, 111b, 111c and 111d. Since all Combustion chambers are designed the same, only the combustion chamber 111b shown in detail. The intake and exhaust valves 115, 116 are one behind the other arranged in alternating order in the cylinder head and are each against the associated inlet valve seat 115a or xluslassventilsitz 116a movable in order to close the intake opening 115b or the exhaust opening 116b or in the opposite direction to open.

As can be seen from Fig. 5, there is a camshaft 181 for each valve 115, 116 a Nooke 181a to the valves 115, 116 via a conventional To open rocker arm device 181b. Return springs 181c close the Valves, if these are not opened by the cams 181a. In this embodiment only one camshaft 181 is used on which the cams ·· 181a are arranged.

As also shown in Figure 5, a carburetor 120 includes two nozzle sleeves 121 and 122, which each direct an air / fuel mixture in the direction of a throttle valve 130 downwards. The Dttsenhülse 121 forms together with the corresponding fuel lines a high-load circuit, with your the mixture is fed to the combustion chamber under high load conditions is, while the nozzle sleeve 122 lines together with the corresponding fuel forms a low-load circuit with which the mixture is fed to the combustion chamber in low load conditions. The latter circuit also works in high stress conditions. Both Circles, create a lean mix, preferably in a mixing area between 16 and 20. The throttle means 130 include a throttle

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flap for each of the nozzle sleeves 121 and 122, these throttle flaps are coordinated with each other and used for the same number of combustion chambers. It is therefore referred to as a single choke.

The one in Pig. 5 carburetor shown is a conventional carburetor and has no special features. The puncture of the carburetor is the same as the carburetor 20 in that it receives air from an air filter A and a certain amount of fuel through the nozzle sleeves into the air stream mixes to form an air / fuel mixture that flows into the intake manifold. The intake manifold then directs the air / fuel mixture over the Intake lines 112 $, 112b, 112c and 1T2d into the respective combustion chamber. The intake lines 112a to 112d are branches of the intake manifold that are connected to are connected to the respective combustion chamber.

Exhaust pipes 114a, 114b, 114o and '114d are associated with the exhaust ports 116b connected and lead them into an exhaust system 147 »the one contains thermal reactor 140, which is connected to the thermal reactor 40 is identical.

A section 280 of the suction line 112b corresponds in construction, Purpose and effect of the already described section 17 and is also arranged adjacent to the intake port to evaporate fuel adhering to the intake pipe. The Absohnitt 280 is also not jacketed or cooled and works in the same temperature range and fttr the same Purpose as in paragraph 17. In an intake manifold arrangement as in Pig. As shown in FIG. 4, the portion 280 adjacent to each suction port is usually sufficient to vaporize the liquid fuel that is present on the suction line

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adheres or flows along it.

Exhaust gas recirculation means 143 to minimize NOx emissions same as the return means used in FIGS. 2 and 3, in that the Exhaust gases are drawn from the reactor 140 through an opening 144. The exhaust gas then flows through line 144a, through a cooling system 145, through an exhaust gas recirculation valve 146 and through .a line 144h into the Intake manifold back. The return valve 146 is closed by a vacuum in the Line 112a controlled, which is below the throttle valve on the intake manifold is attached. Since all suction openings are directly connected to the suction manifold, no separating agents are used, as in the Figures 6 and 7 shown.

The apparatus and methods of the present invention described above can be better understood by considering some of the conditions which exist in a cylinder during the completion of the exhaust stroke and during the beginning of the intake stroke. The pressure in the exhaust line reaches almost atmospheric pressure since. it is a relatively large line. The pressure in the intake line or in the intake manifold after the carburetor varies and depends mainly on the throttle setting . In front of the carburetor there is or is almost ambient pressure, i.e. atmospheric pressure.

When only one throttle valve is used for one cylinder and the throttle valve is opened for high load conditions , the suction pressure at the suction port becomes almost atmospheric pressure. When the exhaust cycle is almost complete and before the top dead center is reached, it is common to open the intake valve while the exhaust valve is always open.

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is still open. This area is called "overlap". The tendency of the gases in the cylinder during the overlap time to exit the open exhaust valve is the greater, the higher the Suction pressure is. When the suction pressure is relatively low, there is a substantial pressure difference, that of the tendency described above counteracts and even an outflow of the gas residues in reverse Direction in the suction line can cause. As a result, the amount of gas residues in the combustion chamber for the next cycle is all the greater, the longer the overlap period or the lower the suction pressure is.

If there is a throttle valve for each combustion chamber and the intake lines are not connected to one another, there is a pressure in each intake line that depends on the conditions in each intake line. However, if the intake lines are connected to one another, such as by NOx return lines, or if there is only one throttle valve for several combustion chambers, a possibly existing low pressure at an intake opening can be transferred to the intake opening of another combustion chamber, whereby the intake pressure or the average pressure in the Suction system is reduced. This phenomenon can cause an increase in the pressure difference between the intake and exhaust systems during the valve overlap time and increase the gas residues, as already described above.

The use of one throttle valve per combustion chamber and the separation of the suction lines from each other, optimizes the conditions during the Overlap time, so that the tightness of the gas residues is reduced, since no

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Combustion chamber reduces the pressure in another intake line.

If exhaust gas recirculation is used and the pressure is in a Suction line could influence the pressure in another suction line, this can be done by using separating means as in FIGS and 7, can be prevented. It follows from this that the advantages that can be achieved by using one throttle valve per combustion chamber also then can be achieved if exhaust gas recirculation is used to reduce NOx emissions.

If the engine according to Figures 2 and 3 operates under high load conditions, where the throttle is fairly wide open, and in the intake lines there is a relatively small vacuum (relatively high suction pressure), a difficulty arises in operating the engine with a lean mixture.

When the engine is started, the exhaust gas recirculation valve V remains closed, which prevents or limits the exhaust gas recirculation during the starting time. It is beneficial to clear the exhaust gases during this time

cannot be fed back into the system as the exhaust gases are numerical ¥ ert of the residue breakage would increase, which is detrimental to the running of the engine could affect.

The exhaust gas control valve 46 opens by reducing the vacuum in of the suction line (increase in suction pressureJ, whereby the respective opening ... of the valve 46 varies according to the degree of vacuum in the suction line. Exhaust gases are released through exit port 44, line 44a, exhaust gas control valve 46 and line 44b. If there is insufficient vacuum

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prevails, valve 46 closes. ''

It can be seen that the amount of gas residue in the exemplary embodiment according to Figures 2 and 3 of the degree of opening of the exhaust gas recirculation valve V depends. The control of the limitation of the exhaust gas recirculation is used to Maintaining a suitable residue breakage value in the event of low stress conditions in the engine. The valve V can either be a simple on-off valve or a Be a regulating valve, which also has an on / off position.

When operating the engine according to Figures 4 and 5 under low load conditions, a lean mixture is generated by the low-load circuit of the carburetor, which is fed to the combustion chamber. The atomization of the liquid fuel, which adheres to the wall of the suction line is caused by the heating of the suction line 112 improved. .The heat of the suction line is big enough to keep the To evaporate the fuel film on the wall in the area of section 280, but not enough to heat the whole mixture. As in the exemplary embodiment according to FIGS. 2 and 3, the mixture in the combustion chamber flows through the hot gas residues continue to evaporate.

When operating the engine according to Figures 4 and 5 under high load conditions, the major part of the air / fuel mixture is from the high-load circuit 150 generated.

In the embodiment according to FIGS. 4 and 5, the exhaust gas recirculation switched off in low load conditions to the numerical Value of the residue breakage due to the omission of exhaust gases in the new mixture to reduce. This control can take place in stages, so that except for the

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lowest load conditions at least a partial return is made possible.

The present invention is typically used on four-stroke internal combustion engines and can be used on engines with any number of cylinders, such as in-line six-cylinder engines, V-8 engines, and four-cylinder engines. The features according to the invention can also be used in so-called stratified intake systems with auxiliary combustion chambers.

Fig. 10 shows an embodiment in which the suction pipe for each cylinder has an upwardly directed recess 12e. A plate 250 is arranged at the free ends of each suction line and extends between the cylinder head and an intake manifold 251 are located. In this intake manifold 251 bores 252 are arranged, which are connected to the suction lines 12 stand to feed the mixture to the engine. Openings 253 in the plates 250 are closed by reed valves 254, which the reed valves 208 in Pig. 6 correspond.

In .Ansaugverteiler 252 a line 255 is arranged, which forms a return line for the exhaust gases. The L _TION 255 is connected by drilling 257 with recesses 256 in the intake manifold. The bores 257 are arranged opposite the openings 253 in the plates 250.

This provides a compact embodiment of the exhaust gas recirculation system achieved.

It is also very advantageous to use the crankcase and / or the fuel tank ' to be connected to an exhaust gas return line. In this way gases,

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which may get into the crankcase next to the piston and / or fuel evaporated in the fuel tank burned in the engine The emission of contaminants is also minimized

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Claims (1)

> 1 PATENT ACCESSORY Four-stroke internal combustion engine with an intake line for each cylinder with an intake port and an intake valve and an exhaust pipe having an exhaust port and an exhaust valve and having a device for supplying air and fuel into the intake line, and is provided with an ignition device for generating an ignition spark on a spark plug in the cylinder, characterized in that that the intake lines are connected to the exhaust of the engine via a valve that controls the flow of exhaust gases to the intake lines regulated. 2) internal combustion engine according to claim 1, characterized in that the Valve with a control dependent on the pressure in a suction line provided · dst when the pressure in the suction line is reduced also reduces the flow of exhaust gases through the valve. 3) internal combustion engine according to claims 1 or 2, characterized in that that the intake lines are connected to one another by an equalization line, with the exhaust gases entering the individual suction lines flow and that means are arranged in this equalizing line to reduce the flow in the event of brief pressure peaks of exhaust gases in the intake lines. 4) internal combustion engine according to claim 3, characterized in that this Limiting means designed as small dttaen in this equalizing line are. 509850/0637 5) Internal combustion engine according to claim 3, characterized in that these limiting means are designed as one-way valves in this equalizing line. ■ · β) internal combustion engine according to one or more of claims 1 to 5 »thereby characterized in that between the exhaust line and the control valve a Cooler for the exhaust gases is arranged. 7) internal combustion engine according to one or more of claims 1 to 6, characterized characterized that between the first. of pressure in a suction line controlled valve and the exhaust line a second valve, controlled by the pressure in an intake line, which controls the flow of Exhaust gases to the first valve depending on the pressure in the intake lines while the first valve regulates the flow of exhaust gases into the intake lines as a function of the pressure in the intake lines regulated. 8) Internal combustion engine according to one or more of claims 3 to 7, characterized characterized in that the equalizing line is arranged in an intake manifold, and that between the intake manifold and the cylinder head a plate is mounted on which reed valves are arranged, which close the connecting bores between the equalizing line and the suction line in the event of short pressure peaks. 9) Internal combustion engine according to claim 8, characterized in that the intake lines are provided with upwardly directed recesses in which the reed valves are accommodated. 509850/0637 Blank page