JPH0835451A - Internal combustion engine with exhaust gas reflux mechanism - Google Patents

Abstract

PURPOSE:To reduce the concentration of NOx by feeding moisture to hot exhaust gas for lowering the temperature thereof, and making the amount of the moisture adjustable. CONSTITUTION:When exhaust gas discharged from an exhaust manifold 6 to an exhaust duct is partly recirculated to an intake manifold via a recirculation exhaust passage, a carburetor 3 is laid in the passage and water supplied from a water tank 1 through a flowrate adjusting valve 2 is vaporized with the carburetor 3 for being mixed with recirculation exhaust gas. The valve 2 is regulated with a controller C to adjust the amount of moisture fed to the carburetor 3 properly. The moisture vaporized in the carburetor 3, after mixed with the recirculation exhaust gas, reaches an exhaust gas recirculation and intake air cooler 9 and is cooled therein. Then, the moisture is mixed with the ordinary intake air in an intake manifold 27. Thus, a substantial change in the concentration of NOx in the summer and winter season is eliminated by adding moisture to the recirculation exhaust gas, and a good NOx reduction effect is thereby provided at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism of an internal combustion engine with an exhaust gas recirculation mechanism for reducing NOx concentration by recirculating exhaust gas in the internal combustion engine and supplying it again to the cylinder head as supply air.

[0002]

2. Description of the Related Art Conventionally, a technique having an exhaust gas recirculation mechanism has been publicly known. The related art is disclosed in the drawings and will be described in each drawing. For the invention of claim 1, the prior art is illustrated in FIGS. 3, 4 and 5. An internal combustion engine with an exhaust gas recirculation mechanism is considered to be a promising technology for reducing NOx concentration, but since high-temperature exhaust gas is recirculated to the air supply side, an increase in air supply temperature cannot be avoided and engine performance is ensured. Requires a large capacity exhaust gas recirculation charge air cooler. There is a correlation between the absolute humidity in the supply air and the NOx concentration as in the prior art shown in FIG.
Although the amount of Ox is small, a large amount of NOx is emitted in winter when the humidity is low. Therefore, as shown in FIG. 3, there is little NOx in the summer, but there is much NOx in the winter, and it is difficult to keep the NOx within the regulation value throughout the year. This phenomenon has a similar tendency in an internal combustion engine with an exhaust gas recirculation mechanism. In order to comply with the strict NOx regulation, it is necessary to add a large-capacity exhaust gas recirculation charge air cooler. However, as shown in FIG. Not. The invention of claim 1 of the present invention improves this point.

With respect to the invention of claim 2, the prior art is disclosed in FIGS. 8, 9, 10 and 11. The internal combustion engine with the exhaust gas recirculation mechanism is an effective method for reducing the NOx concentration, but when the exhaust gas recirculation mechanism is added, the amount of soot in the exhaust gas increases as shown in the graph in FIG. is there. When such exhaust gas containing a large amount of soot is recirculated, the amount of wear of the piston ring, liner, etc. of the internal combustion engine increases, and the durability deteriorates. To prevent this, a soot trap filter for removing soot is required, and in order to prevent the soot trap filter from being clogged, some device or controller is required as shown in FIGS. 8 and 9. 8 and 9, an electronic controller C is provided to automatically control the solenoid valve of the soot trap filter 10. Reference numeral 9 is an exhaust gas recirculation charge air cooler, and 8 is an intercooler for cooling the supply air. This will further increase the cost. Further, as shown in FIG. 10, these clogging prevention devices often have a complicated configuration, and include electronic controller C, air compressor 13, air tank 12, backwash air lines 14, 14, and two sets. Soot trap filters 10a and 10b and two sets of soot hoppers 11 as well.
Therefore, a.11b, heaters 15a and 15b, etc. are required. In addition, a solenoid valve 1 installed in the exhaust gas path from the engine
6a and 16b and the solenoid valves 17a and 17b provided on the backwash air lines 14 and 14 need to be electronically controlled by the controller C. All of this leads to higher costs.

With respect to the invention of claim 3, a prior art is disclosed in FIG. In the prior art,
The soot trap filter 10 is provided with a backwash air line 14. Since the soot is not completely collected in the soot trap filter 10, the soot also flows into the exhaust gas recirculation charge air cooler 9 arranged behind the soot trap filter 10. Therefore, dirt due to soot is generated in the exhaust gas recirculation air supply cooler 9, the heat transfer coefficient is reduced, and the function of the exhaust gas recirculation air supply cooler 9 is no longer fulfilled. Further, the exhaust gas recirculation air supply cooler 9 is closed, and the recirculation exhaust gas does not flow inside the exhaust gas recirculation air supply cooler 9.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art. In claim 1, the NOx concentration is substantially the same in the summer and the winter, and the regulation value is cleared. is there. According to the second aspect of the present invention, the cost of the apparatus is minimized by separating the cylinder that takes out the recirculation exhaust gas from the cylinder that supplies the recirculation exhaust gas, even if the NOx concentration reduction effect is the same. In the third aspect, the clogging of the exhaust gas recirculation charge air cooler 9 is prevented, and the performance of the internal combustion engine with the exhaust gas recirculation mechanism is improved.

[0006]

The problems to be solved by the present invention are as described above. Next, the means for solving the problems will be described. According to the present invention, in an internal combustion engine with an exhaust gas recirculation mechanism that recirculates and burns high-temperature exhaust gas, water is supplied to the high-temperature exhaust gas, the temperature of exhaust gas is lowered, and the amount of water can be adjusted. It is configured to keep the concentration constant.

According to a second aspect of the present invention, in a multi-cylinder internal combustion engine with an exhaust gas recirculation mechanism, a cylinder for taking out recirculated exhaust gas and a cylinder for supplying the recirculated exhaust gas as supply air are different cylinders.

According to a third aspect of the present invention, in an internal combustion engine with an exhaust gas recirculation mechanism, a mechanism for injecting high pressure air to prevent clogging of the exhaust gas recirculation air supply cooler is provided, and the exhaust gas recirculation air supply cooler is clogged. The high pressure air to be prevented is ejected as the air for backwashing the soot trap filter.

[0009]

Next, the operation will be described. According to claim 1, in an internal combustion engine with an exhaust gas recirculation mechanism that recirculates and burns high-temperature exhaust gas, water is supplied to the high-temperature exhaust gas, the exhaust gas temperature is lowered, and the amount of water can be adjusted. Since the NOx level is configured to be constant, the temperature of the recirculated exhaust gas is lowered, so that the capacity of the exhaust recirculated charge air cooler 9 can be reduced. Also, by adjusting the amount of water, high-humidity air can be obtained regardless of atmospheric conditions.
The concentration can be stabilized at a low position. Further, by configuring as in the present invention, there is no reduction in fuel consumption,
Exhaust color is not deteriorated and the flow rate of the recirculated exhaust gas system does not change, so that a complicated exhaust gas system controller is not required.

According to the second aspect of the present invention, in the multi-cylinder internal combustion engine with the exhaust gas recirculation mechanism, the cylinder for taking out the recirculated exhaust gas and the cylinder for supplying the recirculated exhaust gas as the supply air are different cylinders. The effect of lowering the NOx concentration can be exerted in the same manner as the above device, but the cost is the exhaust gas recirculation charge air cooler 9 and the soot trap filter 1.
Since 0 can be reduced and the controller C, the solenoid valve, and the like can be reduced in size, the cost can be reduced.

According to a third aspect of the present invention, in an internal combustion engine with an exhaust gas recirculation mechanism, a mechanism for injecting high pressure air to prevent clogging of the exhaust gas recirculation air supply cooler is provided, and the exhaust gas recirculation air supply cooler is clogged. Since the high pressure air for preventing the above is ejected as the air for backwashing the soot trap filter, it is possible to prevent the exhaust recirculation air supply cooler 9 from being clogged, and the inside of the soot trap filter 10 is also clogged. Since it can be eliminated, the NOx concentration can be reduced, and the performance of reducing the NOx concentration can be maintained for a long time.

[0012]

EXAMPLES Next, examples will be described. 1 is an air supply system diagram showing a mechanism for supplying water to the recirculated exhaust gas, FIG. 2 is a drawing showing the effect of reducing the rate of change of NOx concentration by adding water to the recirculated exhaust gas, and FIG. In the prior art, a drawing showing a state in which the NOx concentration changes when the humidity changes between summer and winter, FIG. 4 shows a relationship between the absolute humidity and the NOx concentration in the prior art, and FIG. 5 shows recirculation exhaust gas in the prior art. Rate, fuel consumption, exhaust color and NO
Drawing showing the relationship of the rate of change of x, FIG.
An air supply circuit diagram showing an embodiment in which a cylinder for collecting the recirculation exhaust and a cylinder for supplying the recirculation exhaust are separately provided. FIG. 7 shows a cylinder for collecting the recirculation exhaust and supplying the recirculation exhaust for the case of 6 cylinders. An air supply circuit diagram showing an embodiment in which the cylinder to be configured is separately configured,
FIG. 8 is a drawing showing a conventional recirculation exhaust system in the case of 6 cylinders,
FIG. 9 is a view showing a conventional recirculation exhaust system in the case of three cylinders.

FIG. 10 is a drawing showing the arrangement of a soot trap filter, an exhaust gas recirculation charge air cooler, a soot hopper, and a heater in a conventional recirculation exhaust system, and FIG. 11 is a change in recirculation exhaust gas ratio, exhaust color, and NOx in the prior art. FIG. 12 is a drawing showing a mechanism for ejecting compressed air to the exhaust gas recirculation charge air cooler 9 to eliminate clogging, and FIG. 13 is a nozzle for eliminating clogging of the exhaust gas recirculation charge air cooler 9. FIG. 14 is a view showing an embodiment in which the compressed air injection nozzle 7 for backwashing the soot trap filter is also used. FIG. 14 shows the compressed air injection nozzle 7 disposed between the exhaust gas recirculation charge air cooler 9 and the soot trap filter 10. FIG. 15 is a view showing an embodiment in which the soot trap is ejected in both directions.
2 is a drawing of an embodiment in which only a backwash air line 14 for backwashing is provided.

The invention of claim 1 will be described with reference to FIGS. 1 and 2. In FIG. 1, a part of the exhaust gas discharged from the exhaust manifold to the exhaust duct is introduced into the recirculation exhaust path. Then, water supplied from the water tank 1 through the flow rate adjusting valve 2 to the recirculation exhaust gas is vaporized by the vaporizer 3 and mixed. The amount of the supplied water is controlled by the controller C. The signals supplied to the controller C as the signals are values of intake air temperature, season, atmospheric conditions, residual oxygen concentration, and the like.
The controller C determines the amount of water required for the flow rate adjusting valve 2 by judging these signals.

The water vaporized by the vaporizer 3 is mixed with the recirculation exhaust gas and supplied to the exhaust gas recirculation air supply cooler 9. Cooled in the exhaust gas recirculation air supply cooler 9, the normal air supply and the recirculation exhaust gas are mixed and supplied to the cylinder 4 of the engine E. By adding water to the recirculated exhaust gas in this manner, as shown in FIG. 2, the NOx concentration, which was greatly changed between summer and winter, can be maintained at a substantially constant NOx concentration. .

Next, referring to FIGS. 6 and 7, the invention of claim 2 will be described. FIG. 6 shows an embodiment with three cylinders. In this embodiment, the cylinders 4a, 4a
Among the b and 4c, the recirculation exhaust gas from the cylinder 4a is configured so as not to pass through the exhaust manifold 6 but to be merged in the silencer 5 through another path, and the throttle valve 21 is connected to the path from the cylinder 4a. Is provided to adjust the amount of exhaust gas reaching the exhaust gas recirculation air supply cooler 9 which is a recirculation exhaust gas system. The exhaust gas after passing through the exhaust gas recirculation charge air cooler 9 is
It is supplied to the other cylinders 4b and 4c. Normal air supply passes through the filter 20 and the air supply manifold 27 to the cylinder 4
a, 4b, 4c. Therefore, the cylinder 4a collects the exhaust gas, but the recirculation exhaust gas is not supplied. On the contrary, the exhaust gas is not collected in the cylinders 4b and 4c, but the recirculated exhaust gas is supplied as the supply air.

In the embodiment of FIG. 7, the embodiment is illustrated in the case of 6 cylinders. That is, the cylinders 4a, 4b, 4c,
Of the cylinders 4d, 4e and 4f, exhaust gas is collected from the cylinders 4a, 4b and 4c and supplied to the cylinders 4d, 4e and 4f as recirculation exhaust gas. Therefore, the cylinders 4a, 4b, 4
Recirculation exhaust gas is not supplied to c, and the cylinders 4d, 4e, 4f
Does not collect exhaust gas.

The exhaust gas from the cylinders 4a, 4b, 4c is provided with a throttle valve 21 after passing through the turbine T1 of the supercharger G1 to collect a part of the exhaust gas and cool the exhaust gas recirculation charge air. Supply to the compressor 9, and to the compressor C2 of the supercharger G2 provided in the exhaust portion of the cylinders 4d, 4e, 4f,
It is supplied to the cylinders 4d, 4e, 4f via the intercooler 19. 20 is a filter. The supercharger G1 is composed of a turbine T1 and a compressor C1,
The supercharger G2 is composed of a turbine T2 and a compressor C2. In addition, the filter 20 and the intercooler 19
Are provided in both cylinders 4a, 4b, 4c and cylinders 4d, 4e, 4f.

Next, the invention of claim 3 will be described with reference to FIGS. 12, 13, and 14. In FIG. 12, the compressed air that has passed through the air tank 12 from the air compressor 13 is supplied to the compressed air injection nozzle 7, and the compressed air injection nozzle 7 eliminates the clogging of the exhaust gas recirculation air supply cooler 9. The air compressor 13 and the air tank 12
The compressed air that has passed through is also used as the air for backwashing the soot trap filter 10.

In the embodiment shown in FIG. 13, the soot trap filter 10 is arranged on the lower side, and the exhaust gas recirculation charge air cooler 9 is arranged on the upper side. The compressed air injection nozzle 7 is disposed above the exhaust gas recirculation air supply cooler 9, and the exhaust gas recirculation air supply cooler 9 and the soot trap filter 10 are simultaneously operated by the compressed air discharged from the compressed air injection nozzle 7. They are backwashing. Further, in the embodiment shown in FIG. 14, the exhaust gas recirculation charge air cooler 9 and the soot trap filter 10 are vertically arranged side by side, but the compressed air injection nozzle 7 is arranged between them and the air tank is provided. 12 to backwash air line 14
・ The compressed air supplied via 14 is supplied to the controller C.
Thus, the solenoid valve 16 is controlled to adjust the amount.

[0021]

Since the present invention is constructed as described above, it has the following effects. In an internal combustion engine with an exhaust gas recirculation mechanism that recirculates and burns high-temperature exhaust gas, water is supplied to the high-temperature exhaust gas to lower the temperature of the exhaust gas, and the amount of water can be adjusted to reduce NOx. Since the level is configured to be constant, the temperature of the recirculated exhaust gas is lowered, so that the capacity of the exhaust recirculated charge air cooler 9 can be reduced. Further, by adjusting the amount of water, high-humidity air can be obtained regardless of atmospheric conditions, so that the NOx concentration of exhaust gas can be stabilized at a low position. Further, with the configuration according to the present invention, the fuel consumption does not decrease, the exhaust color does not deteriorate, and the flow rate of the recirculation exhaust gas system does not change, so that a complicated exhaust gas system controller is not required. Of.

In a multi-cylinder internal combustion engine with an exhaust gas recirculation mechanism, the cylinder for taking out the recirculated exhaust gas and the cylinder for supplying the recirculated exhaust gas as supply air are different cylinders. Although the effect of reducing the NOx concentration can be exhibited in the same manner as the device, the cost is reduced by the exhaust gas recirculation charge air cooler 9 and the soot trap filter 1.
Since 0 can be made small and the controller C, the solenoid valve, etc. can also be made small, the cost can be reduced.

In an internal combustion engine with an exhaust gas recirculation mechanism, a mechanism for injecting high pressure air to prevent clogging of the exhaust gas recirculation air supply cooler is provided, and the exhaust gas recirculation gas supply cooler is clogged. Since the high pressure air to be prevented is ejected as the air for backwashing the soot trap filter, it is possible to prevent the exhaust recirculation air supply cooler 9 from being clogged, and also to eliminate the clogging inside the soot trap filter 10. Therefore, the NOx concentration can be reduced, and the performance of reducing the NOx concentration can be maintained for a long time.

[Brief description of drawings]

FIG. 1 is an air supply system diagram showing a mechanism for supplying water to recirculated exhaust gas.

FIG. 2 is a schematic diagram showing that N is reduced by adding water to the reflux exhaust gas.
The drawing which shows the effect which the change rate of Ox density | concentration became low.

FIG. 3 is a diagram showing a state in which the NOx concentration changes when the humidity changes between summer and winter in the conventional technique.

FIG. 4 is a drawing showing the relationship between absolute humidity and NOx concentration in the prior art.

FIG. 5 is a diagram showing the relationship between the rate of recirculated exhaust gas and the rate of change in fuel consumption, exhaust color, and NOx in the related art.

FIG. 6 is a three-cylinder cylinder that collects recirculation exhaust gas;
FIG. 6 is an air supply circuit diagram showing an embodiment in which a cylinder for supplying recirculated exhaust gas is separately configured.

FIG. 7 is an air supply circuit diagram showing an embodiment in which, in the case of six cylinders, a cylinder for collecting recirculation exhaust and a cylinder for supplying recirculation exhaust are separately configured.

FIG. 8 is a drawing showing a conventional recirculation exhaust system in the case of six cylinders.

FIG. 9 is a drawing showing a conventional recirculation exhaust system in the case of three cylinders.

FIG. 10 is a view showing the arrangement of a soot trap filter, an exhaust gas recirculation charge air cooler, a soot hopper, and a heater in a conventional recirculation exhaust system.

FIG. 11: Recirculation exhaust rate, exhaust color and NO in the prior art
The drawing which shows the relationship of the change rate of x.

FIG. 12 is a view showing a mechanism for ejecting compressed air to the exhaust gas recirculation charge air cooler 9 to eliminate clogging.

FIG. 13 is a view showing an embodiment in which the clogging elimination nozzle of the exhaust gas recirculation charge air cooler 9 is also used as the compressed air injection nozzle 7 for backwashing the soot trap filter.

FIG. 14 is a view showing an embodiment in which a compressed air injection nozzle 7 is arranged between an exhaust gas recirculation charge air cooler 9 and a soot trap filter 10 and ejected in both directions.

FIG. 15 is a drawing of an embodiment in which only a backwash air line 14 for backwashing the soot trap filter 10 is provided in the prior art.

[Explanation of symbols]

 1 Water Tank 2 Flow Control Valve 3 Vaporizer 4 Cylinder 9 Exhaust Gas Recirculation Charge Cooler 10 Soot Trap Filter 12 Air Tank 13 Air Compressor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F01N 3/04 Z

Claims (3)

[Claims] 1. An internal combustion engine with an exhaust gas recirculation mechanism that recirculates and burns high-temperature exhaust gas, supplies water to the high-temperature exhaust gas, lowers the temperature of exhaust gas, and makes it possible to adjust the amount of water, and the NOx concentration. An internal combustion engine with an exhaust gas recirculation mechanism, characterized in that 2. A multi-cylinder internal combustion engine with an exhaust gas recirculation mechanism, wherein a cylinder for taking out recirculated exhaust gas and a cylinder for supplying the recirculated exhaust gas as supply air are separate cylinders. Internal combustion engine. 3. In an internal combustion engine with an exhaust gas recirculation mechanism, a mechanism for injecting high pressure air to prevent clogging of an exhaust gas recirculation air supply cooler is provided, and high pressure air for preventing clogging of the exhaust gas recirculation air supply cooler. Is discharged as air for backwashing the soot trap filter.