KR800000459B1 - Apparatus to decrease emitting nox, hc and co for exhaust gas of internal combustion engine - Google Patents

Abstract

A four-cycle spark-ignition I. C. engine operates to reduce NOx, HC and CO is minimized by means of a lean overall air-fuel ratio. A mixture cloud of relatively rich combustible mixture is formed in a minimum-turbulence main chamver(2) adjacent a torch nozzle(3) restriction at the time of ignition. A thin wall metal cup(29) is positioned within the auxiliary chamber cavity(5) and silated from the engine walls so that it remains hot and prevents condensation of fuel from th rich mixture.

Description

Reduction device for NOX, HC and CO in exhaust gas of internal combustion engine

1 is a side view of a leading and partial cross section showing a preferred embodiment of the present invention.

2 to 4 are cross-sectional views taken along line 2-2, 3-3 and 4-4 of FIG.

5 is a cross-sectional view showing the structural characteristics of a four-cycle internal combustion engine of a preferred type embodying the present invention.

6 is a partially enlarged view of FIG.

FIG. 7 is an enlarged view of a portion of FIG. 1 showing a cam coupling for connection of a throttle valve of two carburetors. FIG.

8 is a diagram showing the continuation of the results in the combustion process.

FIELD OF THE INVENTION The present invention relates to four cycle internal combustion engines, and more particularly to the reduction of nitrogen oxides (NOx), unburned hydrocarbons (HC), and carbon monoxide (CO) in exhaust gases from such engines.

According to the present invention, these three kinds of undesirable components in the exhaust gas are minimized by improvement of the basic combustion method of the internal combustion engine.

Minimization of NOx production is achieved by lowering the maximum combustion temperature. On the other hand, the average combustion temperature is maintained for as long as possible to minimize HC emissions. CO emissions are minimized by providing excess oxygen in the mixed air.

With regard to minimizing the production of NOx, the maximum combustion temperature is controlled so as not to exceed about 1,200 ° C. under the operating conditions of soy flour. This should be compared to the highest combustion temperatures in a typical four cycle gasoline engine, most of which exceed 1,200 ° C. for relatively heavy load conditions.

With regard to minimizing the emission of HC, it is generally known that mixed air adjacent to a relatively low temperature cylinder wall is not completely combusted even when conventional engines operate under the best conditions.

Oxidation of HC is actively promoted when the combustion temperature exceeds about 800 ° C. In a typical four-cycle gasoline engine, the combustion temperature quickly reaches a high value after ignition of the mixed air and rapidly decreases when the combustion gas expands. As a result, the high temperature at which the oxidation of HC actively occurs is a very short period, and as a result, discharge of unburned hydrocarbon HC near the cylinder wall. Thus, in order to minimize HC emissions, the highest combustion temperature in the cylinder is maintained at a relatively high value and possibly over a long period of time.

It is generally known that CO emissions are minimized when the mixed air is thinner than the stoichiometric air-fuel ratio. However, such mixed air is extremely unlikely to ignite, resulting in unstable engine operation, and in extreme cases the mixed air introduced into the cylinder is discharged without combustion. Therefore, in order to minimize CO emissions, it is necessary to improve the combustion method so that the engine can be operated in a stable state by extremely thin mixed air.

The need for NOx emission control is maximum when the engine is operating under high load conditions, and the need for HC emission control is maximum when the engine is idling or operating under light load conditions.

The above time and temperature requirements to achieve minimal emissions of NOx, HC and CO require extremely slow combustion rates of the performance mixed air. In addition, an extremely strong ignition source must be provided to combust the extremely thin mixed air. The flame propagation rate must also be controlled according to the load of the engine in order to achieve the desired combustion temperature.

Improved combustion methods for each cylinder of a four-cycle internal combustion engine include mechanical changes in the "three-valve" engine of the general type as described in Bernhard et al. British Patent No. 948686, issued February 5, 1964; By improvement. In the four-cycle internal combustion engine of this type, each cylinder has a main combustion chamber having a normal intake valve and an exhaust valve, and again there is a third valve control inlet to the auxiliary combustion chamber having an ignition flag. Each auxiliary combustion chamber communicates with each main combustion chamber through a small hole known as a "torch nozzle." Relatively thin performance mixed air is supplied to the main combustion chamber, and relatively rich performance mixed air is supplied to the auxiliary combustion chamber. In operation, the rich mixed air is easily ignited by the ignition floes, and the resulting flame generated through the torch nozzle ignites the lean mixed air in the main combustion chamber.

By the improved combustion method of the present invention, in order to achieve low exhaust emissions with NOx, HC and CO, a conventional "three-valve" engine is modified in several important respects.

(A) the volume of the auxiliary combustion chamber and the peripheral chamber is configured to contain 5% to 12% of the combined volume of the auxiliary combustion chamber hamgye, the cross-sectional area of the torch nozzles per 1cc of the secondary combustion chamber volume of ² to 0.04cm 0.16cm ² It is to be measured.

(B) ratio

Is controlled by a separate vaporizer supplied separately for each chamber. These vaporizers are connected to each other by cam action to adjust the relative position of the throttle valve from the idling to the full engine load of the throttle valve. Αa (the air-fuel ratio of the mixed air supplied to the auxiliary combustion chamber) and αm (the air-fuel ratio of the mixed air supplied to the main combustion chamber) are used to form a desired mixed air cloud in the main combustion chamber. Must be adjusted in relation to

(C) The auxiliary combustion chambers contain thin metal cups isolated from the walls to keep them warm.

(D) The rich mixed mixed air introduced into the auxiliary combustion chamber is first heated in a heat exchange relationship with the hot exhaust gas generated in the main combustion chamber by passing it through a thin metal conduit, and thus almost All fuel is evaporated before entering the auxiliary combustion chamber.

(E) The ignition plug is positioned so that when the rich mixed air is introduced into the auxiliary combustion chamber, the electrode does not become soiled by the collision of the mixed air, and again the spark at the electrode is removed from the main combustion chamber near the end of the compression process. Is not blown away by the flow of gas.

(F) The cross-sectional area of the torch nozzle is made larger than that of the venturi in the vaporizer which supplies the rich mixed air to the auxiliary combustion chamber.

(G) The main combustion chambers formed in the cylinder wall and between the engine head and the piston are not symmetrical, but instead have a large depth on one side of the center line and communicate with the torch nozzle near the portion of maximum depth.

(H) The torch nozzle is directed towards the center of the cylinder and just below the head of the piston at the top dead center (TDC) position.

Other objects and advantages will be apparent from the following.

In the figure, the internal combustion engine has a piston 1 which makes the movable wall of the main combustion chamber 2. The torch nozzle 3 extends between the main combustion chamber 2 and the subcombustion chamber 5, and the subcombustion chamber 5 has an ignition plug 4. The intake passage 6 to the main combustion chamber 2 is controlled by the intake valve 9, and the intake passage 7 to the auxiliary combustion chamber 5 is controlled by the intake valve 10. The exhaust passage 8 from the main combustion chamber 2 is controlled by the exhaust valve 11. These three valves 9, 10 and 11 are installed in the engine head and operated by conventional means including the camshaft 20.

Air penetrated through the air cleaner (13) is mixed with fuel in the periodicizer (14) and the auxiliary vaporizer (15), and the mixed air thus formed is the main intake manifold (16). And through the auxiliary intake pipe 17. Relatively lean mixed air is supplied from the vaporizer 15 to the intake pipe 17. The ignition flash 4 ignites the relatively rich mixed air in the auxiliary combustion chamber 5, and causes the flame to be injected through the torch nozzle 3 to ignite the relatively lean mixed air in the main combustion chamber 2. Exhaust gas from the main combustion chamber 2 passes through the exhaust passage 8 and the exhaust liner 18 to heat the rich mixed air in the tube 17 so that the walls of the fuel passage 7 and the auxiliary combustion chamber 5 are exhausted. Works to avoid condensation on the stomach. The exhaust sand gas from the liner 18 flows out through the liner 19 roll in the manifold 21.

The parts forming the main combustion chamber 2, the torch nozzle 3 and the subcombustion chamber 5 are shown in a diagram in FIG. 1, and a realistic preferred embodiment of these parts is shown in FIG. The valve 9 is removed in FIG. 5 for clarity).

The engine head 23 is fixed to the engine block 12 by conventional means, not shown, and a conventional gasket 24 can be fitted therebetween. The main combustion chamber 2 is formed in the cylinder 25 between the front face of the piston 1 and the curved surface 26 which defines the recessed part in the engine head 23 opposite to the front face of the piston. do. A part of this main combustion chamber 2 is formed by the head of the intake valve 9 and the exhaust valve 11. The recesses in the engine head are not symmetrical and have a maximum depth in the portion of the notch nozzle 3.

This recess coincides with the cylinder bore 25 and also has a circular boundary of approximately the same dimensions. The auxiliary combustion chamber 5 has a gap between the thin cup 29 and the cup 29 formed in the ignition plug recess 28 and the curved surface 27 in the engine head 23. Small enough to have an effect. The head of the valve 10 forms one wall of the auxiliary combustion chamber 5. The cup is held in place by an end protruding flange 30 fitted between the head insulation elements 31, 32. The thin cup 29 has a first hole 36 which matches the torch nozzle 3 and a second hole 34 which communicates with the ignition plug recess 28. A part of the rich mixed air introduced into the auxiliary combustion chamber 5 through the vaporizer 15 penetrates into the main combustion chamber 2 by passing through the torch nozzle 3, and the lean mixing in the main combustion chamber 2. Dispersed in air. The degree of this dispersion mainly depends on the speed of the rich mixed air passing through the torch nozzle 3. The dispersed mixed air near the torch nozzle flows back into the auxiliary combustion chamber 5 during the compression process of the piston 1. According to the present invention, an appropriate amount of mixed air remaining near the torch nozzle at the end of the compression process, and thinner than the mixed air in the auxiliary combustion chamber 5 and darker than the mixed air in the main combustion chamber 2, have an important effect. Found.

This part of the mixed air is called the “mixed air cloud”, and the amount and mixing ratio of the mixed air cloud are λ, the air-fuel ratio (αa) in the auxiliary combustion chamber, the air-fuel ratio (αm) and the auxiliary combustion chamber volume (Va) in the main combustion chamber. And torch nozzle area Ft. Of these elements, elements Va and Ft are determined by the engine structure, and [lambda] aa [alpha] m are determined by the control of the carburetor.

The volume of the auxiliary combustion chamber 5 has an important relationship with the volume of the main combustion chamber when the piston 1 is in the top dead center position. If the volume of the auxiliary combustion chamber 5 is too large compared to the volume of the main combustion chamber 2, the amount of the mixed air cloud at the end of the compression process is small, so that effective combustion of the lean mixed air in the main combustion chamber is expected. Can't. On the contrary, if the auxiliary combustion chamber 5 is too small for the volume of the main combustion chamber 2, the flame energy through the torch nozzle 3 is weak and the lean mixed air in the main combustion chamber 2 is not completely burned. . It was found that the volume of the auxiliary combustion chamber 5 should be 5% to 12% of the total combined volume of the auxiliary combustion chamber 5 and the main combustion chamber 2 when the piston is in the top dead center position as shown.

In addition, if the torch nozzle 3 communicating with the auxiliary combustion chamber 5 and the main combustion chamber 2 becomes too large in cross-sectional area, the speed of the mixed air passing through the torch nozzle is reduced, and as a result, the degree of mixed air dispersion is reduced. It becomes small, and the mixed air cloud becomes relatively thick, but the amount is too small to make a suitable mixed air cloud. Therefore, effective combustion of the lean mixed air in the main combustion chamber cannot be expected. On the other hand, if the torch nozzle is too small in cross-sectional area, the speed of the mixed air passing through the torch nozzle becomes large, and the degree of dispersion of the mixed air becomes wider, and as a result, the desired mixed air cloud cannot be formed. . Of the torch nozzle (3) 0.04cm ² to about 0.16cm ² when the cross-sectional area per 1cc of the secondary combustion chamber volume of the Preferred found that the results are obtained. Complete combustion of the lean mixed gas in the main combustion chamber (2) is necessary for minimizing HC and CO in the exhaust gas, and the characteristics of the complete combustion are determined by proper positioning of the axis (35) of the torch nozzle (3). Is promoted. It has been found that good results are obtained when this axis 35 passes through the center of the piston or is just below it when the piston is in the top dead center position.

ratio

Is controlled by the vaporizers 15, 14 connected in one form so as to create the desired air weight ratio for each operating condition from the idle of the engine to the load. This ratio varies significantly from the idle position to the full throttle position. As shown in FIG. 7, the vaporizer 15 includes a throttle valve 39 operated by an arm 40. Almost equally, the carburetor 14 has a throttle valve 41 actuated by an arm 42 in the cable 43. The arm 42 has a cam face 44 engaged by a cam terminator roller 45 mounted on the arm 40. The spring 46 keeps the roller 35 in contact with the cam face 44. The ratio of the opening of the auxiliary throttle valve 39 to the opening of the main throttle valve 41 is governed by the shape of the surface of the cam 44. In the illustrated embodiment, the angular motion of the main throttle valve 41 and the auxiliary throttle valve 39 is similar in the initial opening stage. However, as the opening of the main throttle valve 41 is increased, the rate of increase of the opening of the auxiliary throttle valve 30 is reduced.

In the operation of the engine, and particularly in the intake process, the lean mixed air is sucked into the main combustion chamber through the intake valve 9 by the vaporizer 14 while the rich mixed air is supplied from the vaporizer 15 to the auxiliary intake valve 10. Through the auxiliary combustion chamber (5). In the suction process, the rich mixed air in the auxiliary combustion chamber 5 is sucked into the main combustion chamber 2 through the torch nozzle 3, and in the compression process, the lean mixed air is reversed through the torch nozzle in the opposite direction. In 2) it is moved into the auxiliary combustion chamber 5, so that the mixed air in the chamber 5 at the time of ignition is thinner than that given earlier in the vaporizer 15. In addition, the performance mixed air in the main combustion chamber 2 at the time of combustion tends to be thicker than that given to the periodicizer 14. The degree of such change in air-fuel ratio in the main and auxiliary combustion chambers is determined by the ratio of the amount of lean and rich mixed air drawn into the two combustion chambers. In this way, the main and auxiliary throttles are changed to change the proportion of the amount of the mixed air supplied to the main and auxiliary combustion chambers at the opening angles of the respective throttle valves, in order to always operate the internal combustion engine with the desired combustion-mixed air. It is necessary to change the value of the opening ratio of the valve 41,39.

The openness ratio between the main and auxiliary valves in the partial opening range can be kept relatively constant to relatively enrich the mixed air in the auxiliary combustion chamber 5, thereby improving the ignition possibility, while the main and auxiliary throttles It will be appreciated that in further larger opening ranges of the valve, the increase in the opening of the auxiliary throttle valve 39 is reduced compared to that of the main throttle valve 41 and thus the overall air-fuel ratio becomes sparse to ensure satisfactory combustion.

It is preferable that the combustion rate in the main combustion chamber 2 is very late, and therefore it is necessary to eliminate excessive turbulence, and for that reason, the recess in the engine head formed by the wall 26 is actually a cylinder bore 25. It has the maximum diameter equal to the diameter of). When the piston reaches the top dead center in this way, there is no “squeeze” portion where the gas must be severely ejected at the end of the compression process. This characteristic again reduces turbulence in the main fuel chamber 2. The thin cup 29 is preferably made of a heat resistant material such as stainless steel and only needs to be about 2 mm thick.

Except for the ignition plug recess 28, the thin cup 29 inevitably defines the outer perimeter of the auxiliary combustion chamber 5. The cup 29 is constructed and tilted to keep hot during operation of the engine. This is because the cup is not in contact with the wall of the engine head 23 that is cooled as the water passage 47 in most of its length. If desired, the space 48 between the thin cup 29 and the wall 27 surrounding the engine head may be filled with a suitable thermoelectric material. However, good results were obtained when this space was left empty. This thin cup has a low heat capacity and is thermally insulated from the engine wall, so that when the engine is started, the cup is heated immediately and kept relatively high during subsequent engine operation. This hot cup prevents the condensation of fuel penetrated into the auxiliary combustion chamber 5 by the valve 10.

In comparison with conventional engines, exhaust gases are generally high in temperature and contain excess oxygen, thus causing oxidation reactions in the exhaust system. In addition, since the suction mixing air is evaporated more completely than in a general engine, the auxiliary suction passage guided to the valve 10 is maintained at a higher temperature. Immediately after the engine light, the exhaust manifold is elevated in temperature, and this heat is used to improve the properties of the mixed air supplied to the auxiliary combustion chamber 5. In order to maintain the temperature of the rich mixed air when it arrives in the auxiliary combustion chamber 5, this rich mixed air is passed through a heat exchange relationship with the exhaust gas. This temperature should not exceed 350 ° C to prevent pre-ignition. It is advantageous to have a single structure so that the exhaust manifold and the intake manifold for the auxiliary combustion chamber 5 are as thin as possible for maximum heat transfer. However, during operation of the engine, the exhaust manifold rises to about 800 ° C., thus reducing its strength and possibly causing mechanical damage. In addition, the heat transferred to the radiant heat and the carburetor boils the fuel in the carburetor and it causes incomplete operation.

As shown in FIGS. 1 to 4, the rich intake pipe 17 and the exhaust pipe 18 have a common wall 50 of relatively thin metal to promote heat transfer. This common wall 50 is formed as a joint portion of the conduits 17 and 18, as shown in FIG. 2 and FIG. A relatively thick box 51 accommodates thin heat conducting conduits 17 and 18, which are provided by conventional means to that part of the engine head 23 having intake and exhaust conduits. Sticks. This box keeps the hot thin heat transfer liner from destructive vibrations of the engine and the passenger car. The auxiliary intake manifold and the exhaust manifold are slightly separated from the front of the connection point with the engine head to absorb heat stress, thereby ensuring safe passenger car operation.

The position of the ignition floc 4 is selected such that its electrode 49 is positioned away from the passage of the rich mixed air which penetrates into the cup 29 between the valve 10 and its fixed position. In this way, the electrode 49 is protected from condensation of the fuel in the rich mixed air. The ignition floc electrode is again positioned such that the torch nozzle 3 and the cup holes 36, 34 have no direct “straight” path to the electrode. In this way, during the compression process of the piston 1, a strong flow of gas from the main combustion chamber 2 to the auxiliary combustion chamber 5 may cause a strong gas wind, which may cause misfire by blowing off the spark between the electrodes 49. Does not cause to. The axis 35 of the torch nozzle 3 is directed to the upper part of the auxiliary combustion chamber 5, while the hole 34 communicating with the ignition plug recess 28 is biased to one side of the biaxial line. Therefore, the ignition flash 4 is sparked without the risk of extinguishing.

The cross-sectional area of the torch nozzle 3 should be determined as the dimension of the venturi 37 to supply the rich mixed air supplied to the auxiliary combustion chamber 5, and the lean mixed air supplied to the main combustion chamber 2 approximately equally. The amount should be determined as the dimension of the venturi 38. The inner wall of the torch nozzle 3 receives carbon deposits after a period of use. The plasticization of the dimension of the torch nozzle by carbon deposition gives limitation.

This limitation, on the other hand, disturbs the proper balance between the rich mixed air supplied by the vaporizer 15 and the lean mixed air supplied by the vaporizer 14. Therefore, the cross-sectional area of the torch nozzle 3 becomes larger than the cross-sectional area of the venturi 37 of the air conditioner 15.

The diagram in FIG. 8 shows in detail the combustion method in the equivalence of the engine embodying the present invention. This diagram shows the pressure and temperature curves of the combustion gas in the main combustion chamber 2 at each position of the crank angle when the appropriate air mixed air is supplied into the main and auxiliary combustion chambers. The temperature value occurs at or near point “T” as shown in FIG.

Point A on the pressure curve indicates the starting point of the pressure propagation to the main combustion chamber 2, and the pressure is generated in the auxiliary combustion chamber after the rich mixed air is ignited and burned. This pressure rise continues to point B.

Point A 'on the temperature curve corresponds to point A on the pressure curve. The low temperature level at point A means that the flame front does not reach the main combustion chamber until that point. Point B 'on the temperature curve corresponds to point B on the pressure curve, where the gas temperature in the main combustion chamber increases after flame propagation occurs in the main combustion chamber in the auxiliary combustion chamber. In other words, the combustion in the auxiliary combustion chamber 5 is completed at the point B or B ', and the flame front is increased in the performance mixed air in the main combustion chamber in the vicinity of the torch nozzle 3. The combustion speed up to the maximum pressure point C is relatively fast, resulting in a rapid rate of temperature rise between the points B 'and C'. After the peak C when the piston starts lowering, the pressure decreases equally. However, the temperature continues to rise after point C ', which means that all of the mixed air in the main combustion chamber (2) is still not completely burned out, and the remaining mixed air continues to burn at a slow rate during the lower piston stroke. Continue.

The big difference in the combustion speed just before point C compared with after point C is due to the difference in the combustion of mixed air in the main combustion chamber 2 near the torch nozzle 3. Combustion in the main combustion chamber 2 continues during the lower stroke of the piston, giving the highest temperature at point D '. The cylinder volume is extremely large in the advantage of the piston stroke, so the maximum combustion temperature is kept sufficiently low compared to that of a conventional internal combustion engine. In a typical internal combustion engine, the maximum temperature occurs at a point not later than 20 ° C to 30 ° C after the top dead center. Point D 'is about 90 ° C after top dead center.

Point E marks the opening point of the exhaust valve. The corresponding temperature is indicated at point E, which is significantly higher than that of a typical four cycle internal combustion engine. Also to be aware of is the extremely late temperature drop after point D '. That means that the remaining mixed air in the main combustion chamber 2 continues to burn during the exhaust stroke of the piston.

The temperature curve is useful for longer periods of time oxidizing hydrocarbons, which can be used more than possible in conventional engines, and for the preheating of suctioned mixed air and the oxidation of unburned hydrocarbons in the exhaust pipe. Indicates that it can be used.

The actual physical test on the automobile engine constructed by the present invention specified the following. In other words, it was specified that emissions of NOx, HC and CO in the exhaust gas were substantially lower than the highest level allowed for 1975 by the US Environmental Protection Agency under the Clean Air Act.

Claims (1)

Torch communicating the following combinations in spark-ignition internal combustion engines, i.e. walls including lampshade pistons forming the main combustion chamber, and walls forming the subcombustion chamber, in order to minimize unnecessary emissions of engine exhaust gases. As a means for forming the nozzle restriction, the volume of the subcombustion chamber is 5% to 12% of the total combined volume of the main chamber and the sub chamber, and the cross-sectional area of the torch nozzle limit is 0.04 to 0.06 cm ² per cubic cm of the volume of the subcombustion chamber. And a means including a venturi draw for supplying rich mixed air to the subcombustion chamber and a means for supplying lean mixed air to the main combustion chamber. The cross-sectional area of the torch nozzle limit is larger than that of the venturi draw. Large and also ignites the mixed air in the inlet chamber to inject flame through the torch nozzle limit to combust the lean mixed air in the main combustion chamber. Means for forming an exhaust passage with means for ignition, a valve communicating with the main combustion chamber, a thin-walled metal conduit for receiving the exhaust gas from the exhaust passage, and a relatively thick wrap around the thin-walled metal conduit. A device for reducing NOx, HC and CO in the exhaust gas of an internal combustion engine, characterized by a combination of a wall housing box and a means for causing the rich mixed air for insufficiency to be heated by exhaust gas in this conduit.

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