JP3531201B2 - Exhaust recirculation system for turbocharged engines - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to exhaust gas recirculation of an engine with a supercharger, for example, in an engine having at least an intake two-valve structure to achieve lean burn by stratifying by in-cylinder flow of intake air (swirl etc.). Regarding the device.

[0002]

2. Description of the Related Art Conventionally, as an intake device for an engine, for example, Japanese Utility Model Laid-Open No. 4-47165 and Japanese Patent Laid-Open No. 3-237.
There is a device described in Japanese Patent No. 126.

That is, the former device disclosed in Japanese Utility Model Laid-Open No. 4-47165 has a primary intake port and a secondary intake port for a single cylinder, and one intake port is a straight port and the other intake port is a intake port. The port is configured as a swirl port, and an intake control valve is provided in the straight port.

The latter device disclosed in Japanese Patent Laid-Open No. 3-237216 has a straight port and a swirl port for a single cylinder, and a so-called SCV swirl control valve is provided in the straight port. At the same time, the theoretical air-fuel ratio (A / F = 14.7,
This is a device configured to close the swirl control valve to generate swirl when performing lean burn operation with an air-fuel ratio leaner than λ = 1).

As described above, in an engine having at least an intake two-valve structure, in-cylinder flow (swirl) is obtained by means for stopping one intake port (the above-mentioned intake control valve and swirl control valve), and stratification is caused by this in-cylinder flow. by allowing combustion to achieve lean burn, but the engine to improve fuel efficiency are known, problems HC emissions and NOx emissions deteriorates in such a conventional engine there were.

The reason why such a problem occurs will be described in detail below. First, regarding the deterioration of the HC emission amount, if a relatively strong in-cylinder air flow is given in order to make the lean combustion limit leaner, the in-cylinder air flow can improve combustion. While you can,
Cooling loss (so-called cold loss) increases due to air flow, and since the air-fuel mixture is lean, the combustion speed decreases, etc.
As shown by the characteristic a in FIG. 19, there is a problem that HC (hydrocarbon, hydrocarbon) increases on the lean side of the air-fuel ratio.

Next, the deterioration of the NOx emission amount will be described. As shown by the characteristic b in FIG. 19, NOx with respect to the air-fuel ratio.
The emission amount is A / F = 14.7 from the region where the air-fuel ratio is rich.
Gradually increases with the stoichiometric air-fuel ratio, and the maximum amount is emitted in the vicinity of A / F = 16.
Although the Ox emission decreases, the NOx purification rate by the three-way catalyst in the catalytic converter installed in the exhaust system is set to a small region around the stoichiometric air-fuel ratio, so the NOx emission decreases on the lean side. However, when the air-fuel ratio is lean, NOx is not purified by the three-way catalyst, resulting in a problem that the NOx emission amount increases. Further, even with a lean air-fuel ratio, a NOx reduction catalyst is being developed for the purpose of purifying NOx, but a sufficient NOx purification rate has not yet been obtained.

Further, as disclosed in Japanese Patent Laid-Open No. 5-86949, a single cylinder has a primary intake port and a secondary intake port, and a secondary intake port is provided with a shutter valve for in-cylinder flow enhancement. While a surge tank and a supercharger are arranged in this order on the upstream side of each intake port, relatively high temperature EGR gas is returned to the intake system (hot EGR) in the low load region of the engine load,
In a high load region, there is an exhaust gas recirculation system for a supercharged engine configured to recirculate relatively low temperature EGR gas to the intake system (cold EGR).

[0009]

However, this conventional device simply switches between cold EGR and hot EGR depending on whether the engine load is high or low, and is a region where the amount of HC emission becomes large under the operating condition of the engine. Since this is not an EGR switching means considering the region where knocking is likely to occur, there are the following problems.

That is, by closing the shutter valve described above,
If the in-cylinder flow is strengthened, lean burn can be achieved by stratification, but as described above, the HC discharge amount increases due to the cooling loss, while the shutter valve is opened to achieve high filling efficiency and high efficiency. When increasing the torque, the temperature in the cylinder rises due to the above-mentioned supercharger, the heat load becomes large, and knocking easily occurs in the entire load range. Here, in the above-mentioned conventional device, since cold EGR and hot EGR are switched according to the magnitude of the load, if the cold region is set and the cold EGR is performed in the lean region, for example, due to the mismatch of the switching timing between cold EGR and hot EGR. NOx
However, there was a problem that HC was increased, which was not sufficient.

[0011] Claim 1 inventions described in the present invention, in consideration of a region area and knocking HC emission amount is large under operating conditions of the engine tends to occur, the cylinder by closing the shutter valve When strengthening the internal flow (swirl) to achieve stratification (lean burn), H due to cooling loss
In the region where the C emission ratio increases, it is possible to suppress the increase of the HC emission ratio by hot EGR and reduce the NOx emission amount, and to increase the filling amount and the torque by opening the shutter valve. The tendency that knocking easily occurs due to an increase in cylinder temperature and an increase in heat load due to the feeder can be suppressed together with NOx by cold EGR , and a set air-fuel ratio line of λ = 1 is provided, In the lean area below the line, the ON / OFF type shutter valve is closed and hot EGR is set, and in the area above the line, the shutter valve is opened and cold EGR is set to hot E
While reducing HC emissions by GR, reducing RawNOx (NOx emitted from the engine) and recirculating high-temperature existing gas, it also suppresses deterioration of lean limit, while supercharging by cold EGR. In the exhaust gas recirculation system for a supercharged engine, which can suppress knocking in a region above the stoichiometric air-fuel ratio where the heat load becomes large, and reduce the exhaust gas temperature to prevent thermal deterioration of the catalyst. For the purpose of provision.

According to a second aspect of the present invention , λ > 1
By providing a set air-fuel ratio line of lean air-fuel ratio range of, and at the low load side of this line shut motor valve closed, and the hot EGR,
On the high load side of this line, the shutter valve opens, cold EG
With R, the above-described lambda = 1 line, the lambda> 1
In a region where relatively low speed knocking is likely to occur between the set air-fuel ratio line and the set air-fuel ratio line of the above, cold EGR is performed to suppress the low speed knocking of the supercharged engine. providing exhaust gas recirculation system shall be the objective.

[0013]

[0014] The invention of claim 3 wherein the this invention, by providing a set line for switching between hot EGR and cold EGR in the middle of the predetermined opening between the fully open and fully closed shutter valve re Niataipu, this Cold EG on the higher load side than the line
By performing hot EGR on the low load side of R, while suppressing an increase in HC emissions due to hot EGR,
By reducing awNOx and recirculating high temperature burnt gas,
It also suppresses deterioration of lean limit, while cold EG
Due to R, knocking can be suppressed in the region where the heat load is large due to supercharging, the exhaust gas temperature can be reduced, and thermal deterioration of the catalyst can be prevented. In addition, the shutter valve is a linear type. An object of the present invention is to provide an exhaust gas recirculation device for an engine with a supercharger, which can increase the degree of freedom when performing EGR in consideration of the intake air charge amount and the volume efficiency.

[0015] The invention of claim 4 wherein the present invention, the second predetermined opening of the high opening degree side first predetermined opening line and a low opening side between the fully open and fully closed shutter valve Li Niataipu Line is provided to perform cold EGR on the high load side of the second predetermined opening line, hot EGR is performed on the low load side of the first predetermined opening line, and cold EGR and hot are performed on the lap portion between both lines. the combined use of EGR, in particular, while compensating for the lack of the EGR amount in the lap portion, suppression of an increase in HC emissions, with the supercharger can achieve a reduction in deterioration suppression and RawNOx the lean limit engine The purpose of the present invention is to provide an exhaust gas recirculation device.

[0016] Claim 5 inventions described in the present invention, in consideration of a region area and knocking HC emission amount is large under operating conditions of the engine tends to occur, lambda ≧ 1
EGR gas of a relatively low temperature is recirculated (cold EGR) on the rich air-fuel ratio side from the set air-fuel ratio line of E, and a relatively high temperature E on the lean air-fuel ratio side of the set air-fuel ratio line of λ ≧ 1
When the GR gas is recirculated (hot EGR) and the air-fuel ratio is lean, the HC emission tends to increase.
In the region where knocking is likely to occur, EGR is performed with GR to have a high gas temperature, good reburnability, and good vaporization and atomization of fuel to suppress the increase in HC emission while reducing NOx emission. Has a low gas temperature due to cold EGR, and performs EGR effective for slowing the combustion speed to lower the cylinder temperature and prevent knocking.
An object of the present invention is to provide an exhaust gas recirculation device for an engine with a supercharger, which can reduce the exhaust gas temperature and prevent thermal deterioration of a catalyst.

According to a sixth aspect of the present invention , λ > 1
By providing a predetermined lean side air-fuel ratio line, cold EGR is performed on the rich air-fuel ratio side of this line, and hot EGR is performed on the lean air-fuel ratio side of this line,
Cold EGR can be suppressed by performing cold EGR in a region where relatively low speed knocking is likely to occur between the line of λ = 1 and the predetermined lean side air-fuel ratio line of λ> 1. An object is to provide an exhaust gas recirculation device for a feed engine.

[0018] The invention of claim 7, wherein the invention, a first predetermined air-fuel ratio line richer the following areas management Ronsora ratio,
A second predetermined air-fuel ratio line on the lean side is provided, and cold EGR is performed on the rich air-fuel ratio side of the second predetermined air-fuel ratio line, while hot EGR is performed on the lean air-fuel ratio side of the first predetermined air-fuel ratio line, and both By using cold EGR and hot EGR together in the lap portion between the lines, it is possible to suppress the increase in the amount of HC emission, suppress the deterioration of the lean limit, and prevent the increase of RawNOx, especially while compensating for the shortage of the EGR amount in this lap portion. An object of the present invention is to provide an exhaust gas recirculation system for a supercharged engine that can be achieved.

[0019] claimed invention in claim 8, wherein, the co Lumpur <br/> de EGR set outside EGR means for recirculating a relatively low temperature of the EGR gas in the downstream catalytic converter, the hot EGR near the exhaust port of the invention It is an object of the present invention to provide an exhaust gas recirculation system for a supercharged engine that can simplify the configuration of the EGR system by setting the external EGR means for recirculating the relatively high temperature EGR gas.

[0020] The invention of claim 9, wherein the invention, host Tsu DOO <br/> EGR is set in the internal EGR for recirculating internal residual gas to the intake side by the intake and exhaust valves overlap, cold EGR is an exhaust system External EGR that recirculates relatively low temperature EGR gas
The exhaust gas recirculation device for an engine with a supercharger, which can set the temperature of hot EGR gas even higher than that of the configuration in which hot EGR is guided from an external pipe and suppress an increase in HC emissions by setting With the goal.

[0021]

Means for Solving the Problems] The inventions of claim 1, wherein the present invention, the primary intake port and a secondary intake port provided for a single cylinder, the cylinder provided in the secondary air intake port A flow-enhancing shutter valve, a supercharger for supercharging intake air, an operating state detecting means for detecting the operating state of the engine, and at least the engine on the low load side based on the output of the operating state detecting means. The air-fuel ratio control means for controlling the air-fuel ratio so that the air-fuel ratio becomes a lean air-fuel ratio, and the shutter valve is closed on the low load side based on the output of the operating state detection means, while on the high load side the above An exhaust gas recirculation system for a supercharged engine, comprising: a first control means for opening a shutter valve, wherein E, which is relatively hot in a shutter valve closed region, corresponds to opening and closing of the shutter valve. And hot EGR means for recirculating R gas, Bei example a cold EGR means for recirculating a relatively low temperature of the EGR gas in the shutter valve opening area, while constituting an upper Symbol shutter valve ON, with off valve OFF type, A first setting means having a set air-fuel ratio line of λ = 1 for switching the shutter valve opening and closing is provided, and the first control means fully closes the shutter valve in a λ> 1 region below the set air-fuel ratio. While performing hot EGR, λ ≦ 1 above the set air-fuel ratio
It is an exhaust gas recirculation device for an engine with a supercharger, which performs cold EGR by fully opening the shutter valve in a region.

The invention according to claim 2 of the present invention is a single
Primary intake port and cylinder provided for the cylinder
Installed in the secondary intake port and the secondary intake port
A supercharged intake valve and a shutter valve for in-cylinder flow enhancement
Supercharger and engine rotation status detection that detects engine operating status
Means and a low load based on the output of the operating state detection means
Side, at least the air-fuel ratio supplied to the engine is lean.
Air-fuel ratio control means for controlling the air-fuel ratio so that it becomes the air-fuel ratio
And on the low load side based on the output of the operating state detection means
Closes the shutter valve, while on the high load side, the shutter valve
With supercharger having first control means for opening the shutter valve
An exhaust gas recirculation system for an engine, wherein the shutter valve is opened.
Corresponding to the closing, the relatively high temperature E
Hot EGR means for circulating GR gas and shutter valve closing
Cold that recirculates relatively low temperature EGR gas in the region
EGR means for turning on / off the shutter valve.
The shutter valve opening / closing switching
2nd installation with a set air-fuel ratio line for the lean air-fuel ratio area
A control means is provided, and the first control means controls the set air-fuel ratio
The shutter valve is fully closed on the low load side from the
Tolerance is higher than the set air-fuel ratio line
On the cargo side, fully open the shutter valve to set the cold EGR
The exhaust gas recirculation system for a supercharged engine
To collect.

The invention according to claim 3 of the present invention comprises a single
Primary intake port and cylinder provided for the cylinder
Installed in the secondary intake port and the secondary intake port
A supercharged intake valve and a shutter valve for in-cylinder flow enhancement
Supercharger and engine rotation status detection that detects engine operating status
Means, an air-fuel ratio control means for controlling the air-fuel ratio so that at least the air-fuel ratio supplied to the engine is a lean air-fuel ratio on the low load side based on the output of the operating state detection means, and the operating state detection means With a supercharger provided with a first control means for closing the shutter valve on the low load side based on the output, while opening the shutter valve on the high load side .
An exhaust gas recirculation system for an engine, wherein the shutter valve is opened.
Corresponding to the closing, the relatively high temperature E
Hot EGR means for circulating GR gas and shutter valve closing
Cold that recirculates relatively low temperature EGR gas in the region
EGR means and the shutter valve from fully closed to fully open
Linear type opening and closing with adjustable opening setting
Between the fully open and fully closed shutter valve
Hot EGR and cold EGR at a predetermined opening in the middle of
The third setting means having a setting line for switching is provided, and
Cold EGR is performed on the higher load side than the setting line
Supercharge to perform hot EGR on the low load side from the setting line
It is characterized by being an exhaust gas recirculation device for an engine with a machine.

The invention according to claim 4 of the present invention comprises a single
Primary intake port and cylinder provided for the cylinder
Installed in the secondary intake port and the secondary intake port
A supercharged intake valve and a shutter valve for in-cylinder flow enhancement
Supercharger and engine rotation status detection that detects engine operating status
Means and a low load based on the output of the operating state detection means
Side, at least the air-fuel ratio supplied to the engine is lean.
Air-fuel ratio control means for controlling the air-fuel ratio so that it becomes the air-fuel ratio
And on the low load side based on the output of the operating state detection means
Closes the shutter valve, while on the high load side, the shutter valve
With supercharger having first control means for opening the shutter valve
An exhaust gas recirculation system for an engine, wherein the shutter valve is opened.
Corresponding to the closing, the relatively high temperature E
Hot EGR means for circulating GR gas and shutter valve closing
Cold that recirculates relatively low temperature EGR gas in the region
EGR means and the shutter valve from fully closed to fully open
Linear type opening and closing with adjustable opening setting
Between the fully open and fully closed shutter valve
At the high opening side, the first predetermined opening line and the low opening side
2 Has a predetermined opening line and has a lap between both lines
A fourth setting means is provided, which is higher or lower than the second predetermined opening line.
Cold EGR is performed on the cargo side, and the first predetermined opening
Engine with supercharger that performs hot EGR on the lower load side than
It is characterized in that it is an exhaust gas recirculation device.

[0025] The inventions of claim 5, wherein the invention comprises a primary intake port and a secondary intake port provided for a single cylinder, the shutter valve for cylinder flow enhancements provided in the secondary air intake port A supercharger for supercharging intake air, a rotation state detection means for detecting the operating state of the engine, and at least the air-fuel ratio supplied to the engine on the low load side based on the output of the operating state detection means is a lean air-fuel ratio. The air-fuel ratio control means for controlling the air-fuel ratio so that it becomes a fuel ratio, and the shutter valve is closed on the low load side based on the output of the operating state detection means, while the shutter valve is opened on the high load side. An exhaust gas recirculation system for a supercharged engine, which comprises a control means of No. 1, and a fifth setting means having a set air-fuel ratio line of λ ≧ 1 for switching between cold EGR and hot EGR. On the other hand, cold EGR in which low-temperature EGR gas is recirculated on the rich air-fuel ratio side of the set air-fuel ratio line is performed, while high-temperature EGR gas is recirculated to cold EGR on the lean air-fuel ratio side of the set air-fuel ratio line. This is an exhaust gas recirculation system for a supercharged engine equipped with a second control means for performing hot EGR.

The invention of claim 6, wherein the present invention is provided with a sixth setting means having a predetermined lean-side air-fuel ratio line co Lumpur <br/> of switching between de EGR and the hot EGR lambda> 1 , An exhaust gas recirculation system for a supercharger engine that performs cold EGR on the rich air-fuel ratio side of the predetermined lean side air-fuel ratio line and performs hot EGR on the lean air-fuel ratio side of the set lean side air-fuel ratio line. Characterize.

The invention of claim 7, wherein the present invention is physical Ronsora ratio following the first in the region on the rich side of the switching between the cold EGR and the hot EGR predetermined air-fuel ratio line and the lean side of the second predetermined air-fuel ratio A seventh setting means having a line and having a lap portion between the two lines is provided, and cold EGR is performed on the rich air-fuel ratio side of the second predetermined air-fuel ratio line, while on the lean air-fuel ratio side of the first predetermined air-fuel ratio line. Hot EG
It is an exhaust gas recirculation device for a supercharged engine that performs R.

The invention of claim 8, wherein the invention, the upper SL cold EGR is relatively low in the downstream catalytic converter EG
The exhaust gas recirculation device for a supercharged engine is set as an external EGR means for recirculating R gas, and the hot EGR is set as an external EGR means for recirculating relatively high temperature EGR gas near an exhaust port. To do.

The invention of claim 9, wherein the invention, the upper Symbol hot EGR is set in the internal EGR for recirculating internal residual gas to the intake side by the intake and exhaust valves overlap, the cold EGR is relatively cool exhaust system It is an exhaust gas recirculation device for an engine with a supercharger, which is set as an external EGR that recirculates EGR gas.

[0030]

[Action and Effect of the Invention] inventions of claim 1, wherein the present invention
According to, as indicated in the claims corresponds diagram in Figure 18, for a single cylinder P1, the primary intake port P2 and secondary intake ports P3 provided, the cylinder provided in the secondary air intake port P3 above O for flow enhancement
An N, OFF type shutter valve P4, a supercharger P5 for supercharging intake air, an operating state detecting means P6 for detecting the operating state of the engine, and a low load side based on the output of the operating state detecting means P6. Then, at least on the low load side based on the output of the air-fuel ratio control means P7 for controlling the air-fuel ratio so that the air-fuel mixture supplied to the engine has a lean air-fuel ratio, and the shutter valve P4 described above on the low load side. On the other hand, in the exhaust gas recirculation device for the supercharged engine, which includes the first control means P8 for opening the shutter valve P4 on the high load side, corresponding to the opening / closing of the shutter valve P4. In the closed region of the shutter valve P4, the hot EGR means P9 circulates the relatively high temperature EGR gas, and in the open region of the shutter valve P4, the cold EGR means P10 is low relative to the hot EGR. To reflux the EGR gas.

That is, when the in-cylinder flow (swirl) is strengthened by closing the shutter valve P4 to achieve stratification (lean burn), the increase in the HC emission ratio due to the cooling loss is caused by the hot EGR. Can be suppressed. Compared with cold EGR, this hot EGR has a higher gas temperature, good reburnability, and good vaporization and atomization of fuel. Therefore, while suppressing the increase in HC emissions, suppressing the deterioration of the lean limit. At the same time, NOx can be reduced by the EGR effect.

On the other hand, when the shutter valve P4 is opened to increase the filling amount and torque, the cylinder temperature rises due to supercharging by the supercharger P5, and knocking occurs due to an increase in heat load. It can be suppressed by cold EGR. Since the cold EGR already has a low gas temperature, the combustion speed can be slowed down, the in-cylinder temperature can be lowered, and knocking can be suppressed.

At the same time, NOx can be reduced by the EGR effect, and the exhaust gas temperature can be reduced by cold EGR, so that thermal deterioration of the catalyst can be prevented.

Moreover ON the aforementioned shutter valve, since it is configured with off valve OFF type, it is possible to simplify the structure of the countrymen valve itself, also ON, since a two-position control of the OFF shutter valve There is an effect that simplification of the opening / closing control can be achieved.

In addition , the above-mentioned first setting means is provided with a set air-fuel ratio line of λ = 1, and in the lean region below this line, the first control means fully closes the ON / OFF type shutter valve to make the hot EGR. Means performs hot EGR, and the first control means turns ON / OFF in the area above the line.
The shutter E valve is fully opened and the cold EGR means performs cold EGR.

As described above, when the shutter valve is fully closed, in which the amount of HC emission tends to increase, by suppressing the amount of HC emission by hot EGR, the RawNOx is reduced and the high temperature gas is recirculated (hot EGR). It also has the effect of suppressing deterioration of the lean limit.

On the other hand, knocking is likely to occur in a region above the stoichiometric air-fuel ratio where the heat load becomes large due to supercharging by the supercharger. However , when the ON / OFF type shutter valve is fully opened, cold EGR causes the gas temperature to rise. Low EGR
By recirculating the gas to slow the combustion speed and lower the in-cylinder temperature, knocking can be suppressed.

According to the second aspect of the present invention ,
The second setting means of the above mentioned providing a set air-fuel ratio line of lean air fuel ratio zone, the first control means in the low-load side of this line, ON, a shutter valve OFF type fully closed, hot EGR means Hot EGR is performed, and on the higher load side than this line, the first control means fully opens the ON / OFF type shutter valve, and the cold EGR means performs cold EGR.

For this reason, cold EGR is performed as described above in the region where relatively low speed knocking such as low, medium and high rotation is likely to occur between the line of λ = 1 and the set air-fuel ratio line of λ> 1. since the, Ru effect there can suppress the slow knocking.

According to the invention of claim 3 wherein the this invention,
The opening can be set from fully closed to fully opened
Since it is composed of a linear type on-off valve that can be adjusted arbitrarily,
A line is installed to switch between hot EGR and cold EGR.
This has the effect of making setting easy. In addition to the effect of the invention described in claim 5, hot EGR and cold EGR are switched by the third setting means at a predetermined opening degree intermediate between the full opening and the full closing of the linear type shutter valve. A setting line is provided so that cold EGR means performs cold EGR on the high load side and hot EGR on the low load side.
Since the means performs hot EGR, the hot EGR suppresses an increase in HC emissions, reduces RawNOx, and suppresses deterioration of the lean limit due to the high temperature gas recirculation, while the cold EGR supercharges the fuel. As a result, knocking can be suppressed in a region where the heat load is large, and the exhaust gas temperature can be reduced to prevent thermal deterioration of the catalyst.

In addition, since the shutter valve is a linear type, there is an effect that the degree of freedom in performing EGR considering the intake charge amount and the volume efficiency is expanded.

According to the invention of claim 4 of the present invention ,
It provided a high degree of opening side first predetermined opening line and low angle side of the second predetermined opening line between the fully open and fully closed linear type shutter valve in the fourth setting means above mentioned, The cold EGR means performs cold EGR on the high load side of the second predetermined opening line, and the hot EGR means performs hot EGR on the low load side of the first predetermined opening line,
In addition, both EGR means operate together in the lap portion between both lines to use the cold EGR and the hot EGR together, so in particular , while supplementing the shortage of the EGR amount in this lap portion, suppressing the increase of the HC emission amount, There is an effect that it is possible to suppress deterioration of the lean limit and prevent increase of RawNOx.

That is, the above-mentioned lap portion (for example, A / F =
(Equivalent to 16 to 20), if only the hot EGR is performed in the region with the largest RawNOx emission amount, the EGR is performed.
If the amount of gas is insufficient and only cold EGR is performed, the gas temperature is already low, so the lean limit deteriorates and RawHC
Hot EGR gas and cold E
By using GR gas together, such a problem can be avoided.

[0044] According to inventions of claim 5 of the present invention,
The above-mentioned fifth setting means is provided with a set air-fuel ratio line of λ ≧ 1 for switching between cold EGR and hot EGR, and the above-mentioned second control means is relatively on the rich air-fuel ratio side of the set air-fuel ratio line of λ ≧ 1. Of low temperature EGR gas (cold EG
R), and the EGR gas having a relatively high temperature is recirculated (hot EGR) on the lean air-fuel ratio side from the set air-fuel ratio line of λ ≧ 1.

For example, when the in-cylinder flow control is performed by using a variable valve timing device (VVT) or the like without using a shutter valve to achieve stratification (lean burn), hot EGR is selected by the air-fuel ratio line. In such an area, hot EGR
As a result, by performing EGR with a high gas temperature, good reburnability, and good vaporization and atomization of fuel, NOx
There is an effect that the emission amount can be reduced and the increase in the HC emission amount can be suppressed.

Further, in the region where the air-fuel ratio is richer than λ ≧ 1 and the cylinder temperature rises due to supercharging, the heat load becomes large and knocking easily occurs, the gas temperature is already low due to cold EGR, EGR effective for slowing combustion speed
By so doing, the temperature inside the cylinder can be lowered to prevent knocking, and the exhaust gas temperature can be reduced to prevent thermal deterioration of the catalyst.

According to the invention of claim 6 of the present invention ,
A predetermined lean-side air-fuel ratio line of lambda> 1 for switching between the cold EGR and the hot EGR provided to the sixth setting means above mentioned,
The second control means performs cold EGR on the rich air-fuel ratio side of the predetermined lean side air-fuel ratio line, and performs hot EGR on the lean air-fuel ratio side of the predetermined lean side air-fuel ratio line.

[0048] This means that the above-described λ = 1 of the line, this λ>
Since cold EGR is performed in a region where relatively low speed knocking is likely to occur with respect to the predetermined lean side air-fuel ratio line of No. 1, cold low speed knocking is effective. .

According to the invention of claim 7 of the present invention ,
In the stoichiometric air-fuel ratio following areas seventh setting means above mentioned is provided a cold EGR and second predetermined air-fuel ratio line of the first predetermined air-fuel ratio line and the lean side of the switching of the rich side and hot EGR, the first The second control unit performs cold EGR on the rich air-fuel ratio side of the second predetermined air-fuel ratio line, and performs hot EGR on the lean air-fuel ratio side of the first predetermined air-fuel ratio line.

That is, in the lap portion between the above-mentioned first and second predetermined air-fuel ratio lines, cold EGR and hot E
Since the GR are used in combination, in particular, while compensating for the lack of the EGR amount in the lap portion, suppression of an increase in HC emissions, there is an effect that can be achieved and reduction of deterioration suppression and RawNOx the lean limit.

Incidentally, the above-mentioned lap portion (for example, A / F = 1)
In the portion corresponding to 6 to 20), if only hot EGR is performed, the EGR amount becomes insufficient, and if only cold EGR is performed, the gas temperature is already low, which leads to deterioration of the lean limit and increase of RawHC. By using the cold EGR gas together, such a problem can be avoided.

According to the invention of claim 8 of the present invention ,
Co Rudo EGR catalytic converter downstream of the relatively low temperature of E
Set the external EGR means to recirculate GR gas, and use hot E
Since the GR is set as the external EGR means for recirculating the relatively high temperature EGR gas near the exhaust port, there is an effect that the configuration of the EGR system can be simplified.

According to the invention of claim 9 of the present invention ,
Ho Tsu DOO EGR is the intake and exhaust valves overlap, details set internal EGR for recirculating internal residual gas to the intake side by the amount of overlap between the valve opening timing of the intake valve and the closing timing of the exhaust valve, cold EGR is Since the comparatively low temperature EGR gas of the exhaust system is set to the external EGR that recirculates to the intake system, the temperature of the hot EGR gas is further increased with respect to the configuration in which the hot EGR gas is guided from the external pipe,
This has the effect of suppressing an increase in emissions.

[0054]

EXAMPLES be described in detail with reference to an embodiment of the invention are described below. (First Embodiment) The drawing shows an exhaust gas recirculation system for a V-type 6-cylinder engine with a supercharger, in which a purified air outlet of an air cleaner 2 in which an element 1 is arranged in FIG. A body 4 is attached, a throttle valve 5 is arranged in a throttle chamber in the throttle body 4, and a throttle sensor 6 is attached to the above-mentioned throttle body 4.

Further, a bypass passage 7 for bypassing the above-mentioned throttle valve 5 is provided, and an ISC is provided in this bypass passage 7.
(Idle speed control) Valve 8 is installed.

[0056] with disposing the intercooler 10 via the Risho Lum compressor 9 as a high-density supercharger is mechanically driven by a throttle valve 5 in the downstream engine of the above-mentioned throttle chamber, Li Scholl beam compressor 9 above and A bypass passage 11 that bypasses the intercooler 10 is provided, and the ABV is provided in the bypass passage 11.
An (air bypass valve) 12 is provided.

An upstream intake passage 14 is connected to a merging portion 13 where the outlet portion and the bypass passage 11 merge at the outlet portion of the intercooler 10 described above.
The downstream end of 4 is branched at a branch portion 15 into an intake passage 16 for one bank and an intake passage 17 for the other bank.

Each of the above intake passages 16 and 17 is connected to the corresponding surge tanks 18 and 19 on the bank side, and the end portions of the cylinders in the surge tanks 18 and 19 on both banks are communicated with each other through the communication passage 20. Along with this, a variable intake control valve 21 (hereinafter simply referred to as VRIS valve) is installed in the communication passage 20, and the VRIS valve 21 is configured to close at low speed and open at high speed.
6, 17 are configured to use each element 16-20 for inspiratory resonance at high speed.

By the way, the cylinder bore 2 for a total of 6 cylinders
2 ... each have two intake ports 23, 2 per cylinder
4 is provided to connect the intake ports 23 and 24 to the corresponding surge tanks 18 and 19, and
One of the intake ports 23, 23, that is, a secondary intake port (hereinafter simply referred to as an S port) is provided with a shutter valve 25 ... The three shutter valves 25 arranged in the cylinder row direction are integrally connected by valve shafts 26, 26, and the valve shafts 26, 2 described above are connected by an actuator (not shown).
The shutter valves 25, ... The above-mentioned shutter valves 25 are mounted on the downstream side injector 27 provided at the S port 23 and the other intake port 24, that is, the primary intake port (hereinafter simply referred to as P port).
Of course, the valve operating system is not shown in FIG. The upstream injector 28 is arranged on the upper end side of the above-described Rismolum compressor 9.

On the other hand, two exhaust ports 29 per cylinder,
An exhaust manifold 30 is attached to the cylinder head so as to communicate with each of the exhaust ports 29, 29 while the intake valve 2 is provided to form a four-valve structure with two intake valves and two exhaust valves. An exhaust passage 31 is connected to the downstream side of the exhaust manifold 30, and a catalytic converter 32 for purifying exhaust gas is provided in the exhaust passage 31.

By the way, for the purpose of recirculating the relatively high temperature EGR gas near the exhaust port 29 to the intake system, the exhaust manifold 30 is provided with an external hot EGR passage 33, a collecting chamber 34, and EGR branch pipes 35, 35. The above-mentioned external hot EGR system path 36 leading to each of the P ports 24 ...
A valve 37 is provided.

For the purpose of recirculating the relatively low temperature EGR gas downstream of the catalytic converter 32 to the intake system, an external cold is provided between the exhaust passage 31 downstream of the catalytic converter 32 and the intake passage upstream of the Rishorum compressor 9. The external cold EGR passage 38 communicates with each other, and the external cold EGR passage 38 is provided with a carbon trap 39, an EGR cooler 40, and a second EGR valve 41.
The GR system path 42 is configured. In addition, in FIG.
Is the exhaust manifold 30 for detecting the actual air-fuel ratio.
Is a linear O ₂ sensor attached to the.

Further, in this embodiment, the valve timing is set so that the effective compression ratio is smaller than the effective expansion ratio, and the intake intake is closed late (specifically, the general engine late closing timings ABDC50-55). A degree
Even if the amount of intake air is small, the amount of air flowing into the cylinder is increased and pumping loss is reduced by pushing backflow from the cylinder with the intake air of BDC 70 degrees) and by pushing backflow from the cylinder. I am configuring.

FIG. 2 shows a control circuit of an exhaust gas recirculation system for a supercharged engine. The CPU 50 has an intake air amount Q from the air flow sensor 3, an engine speed Ne from the distributor 44, and an empty air from the linear O 2 sensor 43. Fuel ratio A
/ F, the water temperature t of the engine cooling water from the water temperature sensor 45,
Based on various necessary signal inputs such as the throttle opening TVO from the throttle sensor 6, according to a program stored in the ROM 46, the ISC valve 8, the ABV 12,
A variable valve timing device (so-called a variable valve timing device that controls the overlap amount of the intake and exhaust valves by varying the valve timing (including the valve lift amount) of the upstream injector 28, the downstream injector 27, the shutter valve 25, the VRIS valve 21, and the intake valve. VVT) 47, first EGR valve 37, second
The EGR valve 41 is driven and controlled, and the RAM 48 stores necessary data and maps such as the first map M1 shown in FIG.

In the first embodiment, the shutter valve 25 described above is used.
Is an ON / OFF type on-off valve. Further, the above-mentioned first map M1 (see FIG. 3) shows the engine speed N on the horizontal axis.
e and the load (CE = Q / Ne) on the vertical axis, λ = 1 (theoretical air-fuel ratio) for switching the opening / closing of the shutter valve 25.
The set air-fuel ratio line L1 of
1, the shutter valve 25 is fully closed on the low load side and the region where hot EGR (recirculation of relatively high temperature EGR gas) is performed, and the shutter valve 25 is fully opened on the high load side from the above set air-fuel ratio line L1. And cold E
It is a first setting unit that partitions and sets an area for performing GR (recirculation of EGR gas of relatively low temperature) and an EGR inhibition area.

Further, the CPU 50 described above has at least the driving state detecting means (see steps S1 and S2 in the flowchart shown in FIG. 4) for detecting the operating state of the engine and at least on the low load side based on the output of the driving state detecting means. Air-fuel ratio control means for controlling the air-fuel ratio so that the air-fuel ratio A / F supplied to the engine becomes lean air-fuel ratio λ> 1, and the shutter described above on the low load side based on the output of the operating state detection means described above. The valve 25 is closed (closed) while the shutter valve 25 described above is opened (opened) on the high load side (each step S in the flowchart shown in FIG. 4).
6, S7) and hot EGR means for recirculating relatively high temperature EGR gas in the shutter valve closed region in response to the opening / closing of the shutter valve 25 (see the sixth step S6 of the flowchart shown in FIG. 4). And also serves as a cold EGR means (see seventh step S7 of the flowchart shown in FIG. 4) for recirculating relatively low temperature EGR gas in the shutter valve open region.

[0067] details the effect of exhaust gas recirculation apparatus thus constituted engine with a supercharger (embodiment corresponding to Claim 1), in the following with reference to the flowchart shown in FIG.

In the first step S1, the CPU 50 executes reading of various necessary signal inputs such as the intake air amount Q and the engine speed Ne, and in the second step S2, the CPU 5
In the case of 0, the load CE is calculated by the calculation expression CE = Q / Ne.

Next, in a third step S3, the CPU 50 determines whether or not the current engine operating state is less than the set air-fuel ratio line L1 of the first map M1 shown in FIG. 3, and Y less than L1 is determined.
At the time of ES determination, the process proceeds to the next fourth step S4,
When NO is determined to be L1 or more, the process proceeds to another seventh step S7.

In the above-described fourth step S4, the CPU 50 determines whether or not the current engine operating state is in the EGR prohibition region of the first map M1 shown in FIG. 3, and if YES in the region, the CPU proceeds to the next fifth step. Then, when NO is determined outside the region, another sixth step S6 is performed.

In the above-described fifth step S5, the CPU 50 closes the first and second EGR valves 37 and 41 to set E
Prohibit the recirculation of GR gas, and in the above-mentioned sixth step S6,
The CPU 50 fully closes the shutter valve 25 and
While the EGR valve 37 is opened to recirculate the relatively high temperature EGR gas from the external hot EGR system passage 36 to the intake system, in the seventh step S7 described above, the CPU 50 causes the shutter valve 2 to operate.
5 is fully opened, the second EGR valve 38 is opened, and the EGR gas of relatively low temperature from the external cold EGR passage 42 is circulated to the intake system.

That is, on the low load side, the shutter valve 2 described above is used.
When NO. 5 is closed and the in-cylinder flow is strengthened to achieve stratification (lean burn), the amount of NOx that cannot be processed by a three-way catalyst or the like is reduced by hot EGR. This hot EGR
Has a high gas temperature, good reburnability, and good vaporization and atomization of fuel.
It is possible to suppress an increase in the amount of C emission, and in addition, it is possible to reduce NOx and pumping loss due to the EGR effect of circulating the EGR gas.

On the other hand, when the shutter valve 25 is opened on the high load side to achieve high charging efficiency and high torque, the cylinder temperature rises due to the high supercharging of the Rishorum compressor 9 of the Miller cycle engine. , The heat load becomes large and knocking is likely to occur in the entire load range.
Suppressed by cold EGR. That is, since the cold EGR has a low gas temperature, the combustion speed can be slowed down, and the in-cylinder temperature can be lowered to prevent knocking. In addition, since the exhaust gas temperature can be reduced by the circulation of the cold EGR gas while the NOx is reduced by the EGR effect, it is possible to suppress the thermal deterioration of the catalyst.

Further, the shutter valve 25 described above is turned on and off.
Since it is composed of the F type opening / closing valve, there is an effect that the structure of the shutter valve 25 itself and the opening / closing control of the shutter valve 25 become easy.

Moreover, the above-mentioned first setting means (the map of FIG. 3) is used.
(Refer to M1), and a set air-fuel ratio line L1 with λ = 1
In the lean area below this line L1, the first control means
Steps S6 and S7) are ON / OFF type sh
Valve 25 is fully closed, and hot EGR means (step S6
(See) performs hot EGR, and is the area above line L1
Then, the first control means (see steps S6 and S7) turns on O.
Open the N / OFF type shutter valve 25 fully to call
The cold EGR means (see step S7)
To do.

In this way, the HC emission amount tends to increase.
HC is discharged by hot EGR when the shutter valve 25 is fully closed.
The amount of raw NOx is reduced while suppressing the amount of
By recirculating natural gas (hot EGR), lean
There is an effect that the deterioration of the limit can be suppressed.

On the other hand, the supercharger (Rishorum compressor 9
(See), which causes a large heat load due to supercharging
Knocking easily occurs in the area, but O
Call when the N, OFF type shutter valve 25 is fully opened
The EGR gas whose gas temperature is already low is circulated by de EGR.
To slow down the combustion speed and lower the cylinder temperature,
There is an effect of suppressing the locking.

[0078] Incidentally, showing the respective emission state of change of NOx and HC in the case of performing the hot EGR and cold EGR in FIG.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. However, the circuit device of FIGS. 1 and 2 is also used in this embodiment. In the second map M2 shown in FIG. 6, the horizontal axis represents the engine speed Ne and the vertical axis represents the load CE = Q / N.
By taking e, the set air-fuel ratio line L2 (hereinafter simply referred to as line L) in the lean air-fuel ratio region for switching the opening / closing of the shutter valve 25 described above.
2), the shutter valve 25 is fully closed on the low load side of the line L2, and the shutter valve 25 is fully opened on the region where hot EGR is performed and on the high load side of the line L2. And cold E
It is a second setting means that partitions and sets an area for performing GR and an EGR prohibited area.

Further, the CPU 50 supplies at least the engine on the low load side based on the output of the operating state detecting means (see steps S11 and S12 in the flowchart shown in FIG. 7) for detecting the operating state of the engine and the operating state detecting means. Based on the output of the air-fuel ratio control means for controlling the air-fuel ratio so that the air-fuel ratio A / F is set to be lean air-fuel ratio λ> 1, and the above-mentioned operating state detection means (see steps S11 and S12) The first control means (see steps S16 and S17 in the flowchart shown in FIG. 7) that closes the shutter valve 25 on the side while opening the shutter valve 25 on the high load side, and the shutter valve described above. corresponds to the opening 25, the hot EGR means for recirculating a relatively high temperature of the EGR gas in the closed region of the shutter valve 25 (the flowchart shown in FIG. 7 6 See step S16), and the opening area of the shutter valve 25 also serves as a cold EGR means for recirculating a relatively low temperature of the EGR gas (see seventh step S17 in the flowchart shown in FIG. 7).

The operation of the exhaust gas recirculation system for an engine with a supercharger (embodiment corresponding to claim 2 ) thus constructed will be described in detail below with reference to the flow chart shown in FIG.

In the first step S11, the CPU 50 executes the reading of various necessary signal inputs such as the intake air amount Q and the engine speed Ne, and in the next step S12 the CPU 5
In the case of 0, the load CE is calculated by the calculation expression CE = Q / Ne.

Next, in a third step S13, the CPU 50 determines whether or not the current engine operating state is less than the line L2 of the second map M2 shown in FIG. 6, and when the YES determination is less than L2, the next fourth step S14. On the other hand, when NO is determined to be equal to or greater than L2, the process proceeds to another seventh step S17.

In the above-mentioned fourth step S14, the CPU 50
Is the second map M2 in which the current engine operating state is shown in FIG.
Of the EGR prohibited area is determined, and if the determination is YES within the area, the process proceeds to the next fifth step S15, and the NO outside the area is determined.
At the time of determination, the process proceeds to another sixth step S16.

In the above-mentioned fifth step S15, the CPU 50
Closes the first and second EGR valves 37 and 41,
The EGR gas recirculation is prohibited, and the above-described sixth step S16 is performed.
Then, the CPU 50 fully closes the shutter valve 25 and
The first EGR valve 37 is opened and the external hot EGR system path 36 is opened.
While the relatively high temperature EGR gas from is recirculated to the intake system, in the above-described seventh step S17, the CPU 50 fully opens the shutter valve 25 and opens the second EGR valve 38 from the external cold EGR system path 42. The relatively low temperature EGR gas is recirculated to the intake system.

That is, when the above-mentioned shutter valve 25 is closed on the low load side of the line L2 to strengthen the in-cylinder flow and achieve stratification (lean burn), the NOx emission amount is reduced by hot EGR. . This hot EGR has a high gas temperature and good re-combustibility, and since the vaporization and atomization of the fuel are also good, it is possible to suppress an increase in the amount of HC emissions. In addition, the EGR effect of recirculating the EGR gas causes There is an effect that the pumping loss can be reduced.

On the other hand, when the shutter valve 25 is opened on the higher load side than the line L2 to achieve high charging efficiency and high torque, the cylinder temperature is increased by the high supercharging of the Rishorum compressor 9 of the Miller cycle engine. Is increased, the heat load becomes large, and knocking is likely to occur in the entire load region by cold EGR. That is, since the cold EGR has a low gas temperature, the combustion speed can be slowed down, and the in-cylinder temperature can be lowered to prevent knocking. in addition,
Cold E while reducing NOx by EGR effect
Since the exhaust gas temperature can be reduced by the circulation of the GR gas, there is an effect that the thermal deterioration of the catalyst can be suppressed. Moreover, since cold EGR is performed as described above in the region where relatively low speed knocking is likely to occur between the line L1 and the line L2 shown in FIG. 6, such low speed knocking is suppressed. There is an effect that can be.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. However, the circuit device of FIGS. 1 and 2 is also used in this embodiment. In the third map M3 shown in FIG. 8, the horizontal axis represents the engine speed Ne and the vertical axis represents the load CE = Q / N.
By taking e, the hot EGR and cold E at a predetermined opening between the fully open line L3 and the fully closed line L4 of the shutter valve 25.
A setting line L5 for switching between GR and GR is provided, and a linear type shutter valve 25 is provided between the lines L3 and L4.
Set to the linear control range of the opening of the
The third setting means partitions the higher load side into the cold EGR region, the lower load side from the line L5 into the hot EGR region, and further sets the low rotation and low load region into the EGR prohibited region.

Here, the above-described CPU 50 operates on the low load side based on the output of the operating state detecting means (see steps S21 and S22 in the flowchart shown in FIG. 9) for detecting the operating state of the engine and the operating state detecting means. At least the air-fuel ratio A / F supplied to the engine is lean air-fuel ratio λ> 1
So that the shutter valve 25 is closed on the low load side based on the output of the air-fuel ratio control means for controlling the air-fuel ratio so as to obtain the above-mentioned shutter valve 25 on the high load side. A first control means (see steps S31 and S33 in the flowchart shown in FIG. 9) for opening
Corresponding to the opening degree of the shutter valve 25 described above, hot EGR means (see steps S26 and S32 in the flowchart shown in FIG. 9) for recirculating relatively high temperature EGR gas in a region less than the line L5 and the line L5. In the above region, cold EGR means for circulating EGR gas of relatively low temperature (each step S27, S3 in the flowchart shown in FIG. 9)
See also 4).

The operation of the exhaust gas recirculation system for an engine with a supercharger (embodiment corresponding to claim 3 ) thus constructed will be described in detail below with reference to the flow chart shown in FIG.

In the first step S21, the CPU 50 executes the reading of various necessary signal inputs such as the intake air amount Q, the engine speed Ne, etc., and in the next step S22 the CPU 5
In the case of 0, the load CE is calculated by the calculation expression CE = Q / Ne.

Next, in a third step S23, the CPU 50 determines whether or not the current engine operating state is in the linear region in the third map M3 of FIG. 8, and if YES is determined, the process proceeds to the next fourth step S24, If NO is determined, the process proceeds to another eighth step S28.

In the above-mentioned fourth step S24, the CPU 50
After linearly controlling the shutter valve 25 according to the load,
In the next fifth step S25, the CPU 50 determines whether or not the current engine operating state is less than the line L5 of the third map M3 shown in FIG. 8, and when the YES determination is less than L5, moves to the next sixth step S26. , L5 or more is determined, the process proceeds to another seventh step S27.

In the above-mentioned sixth step S26, the CPU 5
0 opens the first EGR valve 37 to recirculate the relatively high temperature EGR gas from the external hot EGR system path 36 to the intake system, while the above-mentioned seventh step S27 causes the CPU 50 to execute the second
The EGR valve 38 is opened to recirculate the relatively low temperature EGR gas from the external cold EGR system passage 42 to the intake system.

In the above-mentioned eighth step S28, the CPU
Reference numeral 50 executes load determination, and when the load is low, the process proceeds to the next ninth step S29, while when the load is high, the process proceeds to another thirteenth step S33.

In the above-mentioned ninth step S29, the CPU 50
Determines whether or not the current engine operating state is within the EGR prohibition region, and moves to the next tenth step S30 when the YES determination is made, and another eleventh step S3 when the NO determination is made.
Move to 1.

In the tenth step S30 described above, the CPU 5
When 0, the first and second EGR valves 37 and 41 are closed to prohibit the recirculation of EGR gas.

In the eleventh step S31 described above, the CPU 5
0 completely closes the linear type shutter valve 25, and in the next twelfth step S32, the CPU 50 causes the first EGR valve 37 to close.
Is opened to recirculate the relatively high temperature EGR gas from the external hot EGR system path 36 to the intake system, while the CPU 50 fully opens the shutter valve 25 in the above thirteenth step S33, and in the following fourteenth step S34. , CPU50 is the second E
The GR valve 38 is opened to recirculate relatively low temperature EGR gas from the external cold EGR system passage 42 to the intake system.

As described above, since the shutter valve 25 is constituted by the linear type opening / closing valve whose opening degree can be arbitrarily adjusted from fully closed to fully opened, the hot EGR and cold E
This has the effect of facilitating the setting of the line L5 for switching to GR.

The above-mentioned third setting means (see the map M3 in FIG. 8)
)) To open and close the linear type shutter valve 25
Hot EGR and cold EGR at a predetermined opening in the middle
Setting line L5 for switching the
Cold EGR means (steps S27, S
34) performs cold EGR, and on the low load side,
The EGR means (see steps S26 and S32) is hot
Since EGR is performed, the amount of HC emissions can be reduced by hot EGR.
While suppressing the increase, RawNOx is reduced and high temperature
Suppressing lean limit deterioration by recirculating gas already
On the other hand, cold EGR causes a large heat load due to supercharging.
Knocking can be suppressed in
In addition, the exhaust gas temperature is reduced to prevent thermal deterioration of the catalyst.
There is an effect that can be.

[0102] Further, the shutter valve 25 is a linear type, there is an effect that it is possible to increase the degree of freedom when performing EGR considering the intake air charging amount and volumetric efficiency. In addition, in other respects, the same operation and effect as those of the previous embodiment are obtained.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIGS. However, the circuit device of FIGS. 1 and 2 is also used in this embodiment. The fourth map M shown in FIG.
4, the horizontal axis represents the engine speed Ne and the vertical axis represents the load CE.
= Q / Ne, the fully open line L3 of the shutter valve 25
And a fully closed line L4, a first predetermined opening line L6 on the high opening side and a second predetermined opening line L7 on the low opening side are provided, and a cold EGR is provided on the higher load side than the line L7. Hot EG on the low load side of line L6 in the area
Each of them is set to the R region, and the lap portion between both lines L6 and L7 is set to the lap region where hot EGR and cold EGR are used together, and further the low rotation and low load region is EGR.
A fourth setting unit that partitions set to prohibited areas.

Here, the above-mentioned CPU 50 at least on the low load side based on the output of the operating state detecting means (see steps S41 and S42 in the flowchart shown in FIG. 11) for detecting the operating state of the engine and the operating state detecting means. The air-fuel ratio A / F supplied to the engine is lean air-fuel ratio λ> 1
The air-fuel ratio control means for controlling the air-fuel ratio so that the air-fuel ratio and the output of the above-mentioned operating state detection means (see steps S41 and S42) close the shutter valve 25 on the low load side while the high load is closed. On the side, the first control means (see steps S53 and S55 in the flowchart shown in FIG. 11) for opening the shutter valve 25 and the shutter valve 2 described above are provided.
Corresponding to the opening degree of 5, the hot EGR means (Fig.
(Refer to the ninth step S49 of the flowchart shown in FIG. 1)
In the region above the line L7, it also serves as cold EGR means (see eighth step S48 in the flowchart shown in FIG. 11) for recirculating relatively low temperature EGR gas.

The operation of the exhaust gas recirculation system for an engine with a supercharger (embodiment corresponding to claim 4 ) thus constructed will be described in detail below with reference to the flow chart shown in FIG.

In the first step S41, the CPU 50 executes the reading of various necessary signal inputs such as the intake air amount Q, the engine speed Ne, etc., and in the next second step S42, the CP 50
U50 calculates the load CE by the calculation formula CE = Q / Ne.

Next, in a third step S43, the CPU 50 determines that the current engine operating state is the fourth map M4 shown in FIG.
It is determined whether or not it is the linear region in step S44. If YES is determined, the process proceeds to the next fourth step S44, while if NO is determined, the process proceeds to another step S50.

In the above-mentioned fourth step S44, the CPU 50
After linearly controlling the shutter valve 25 according to the load,
In the next fifth step S45, the CPU 50 determines whether or not the current engine operating state is in the lap region (see between L6 and L7) of the fourth map M4 shown in FIG. 10, and if YES is determined, the next sixth step S46. On the other hand, when NO is determined, the process proceeds to another seventh step.

In the above-mentioned sixth step S46, the CPU 50
Opens both the first and second EGR valves 37 and 38 to allow the relatively high temperature EG from the external hot EGR system path 36.
Both the R gas and the relatively low temperature EGR gas from the external cold EGR system passage 42 are recirculated to the intake system.

On the other hand, in the above-mentioned seventh step S47, CP
U50 determines whether or not the current engine operating state is above the line L6 outside the lap region of the linear region, and YES.
When the determination is made, the process proceeds to the next eighth step S48, and when the NO determination is made, the process proceeds to another ninth step S49.

In the above-mentioned eighth step S48, the CPU 50
Opens the second EGR valve 38 to recirculate a relatively low temperature EGR gas from the external cold EGR system passage 42 to the intake system (cord).
In the ninth step S49, the CPU 50 opens the first EGR valve 37 to open the external EG.
Relatively high temperature EGR gas from the R passage 36 is returned to the intake system (hot EGR) .

In the tenth step S50 described above, the CP
U50 executes load judgment for areas other than the linear range,
When the load is low, the process proceeds to the next eleventh step S51, while when the load is high, the process proceeds to another fifteenth step S55.

In the eleventh step S51 described above, the CPU 5
It is determined whether or not 0 is in the EGR prohibited basin, the process proceeds to the next twelfth step S52 if the determination is YES, and proceeds to another thirteenth step S53 if the determination is NO.

In the above-mentioned twelfth step S52, the CPU 5
When 0, the first and second EGR valves 37 and 41 are closed to prohibit the recirculation of EGR gas, and in the above thirteenth step S53, the CPU 50 fully closes the shutter valve 25, and the next fourteenth step is performed. In step S54, the CPU 50 opens the first EGR valve 37 to recirculate the relatively high temperature EGR gas from the external EGR passage 36 to the intake system (hot EGR) .

On the other hand, in the above-mentioned fifteenth step S55,
The CPU 50 fully opens the shutter valve 25, and in the next 16th step S56, the CPU 50 opens the second EGR valve 38, and the E of the comparatively low temperature is discharged from the external cold EGR system path 42.
The GR gas is returned to the intake system (cold EGR) .

In short , the above-mentioned fourth setting means (see the fourth map M4) causes the first predetermined opening line L6 on the high opening side between the fully opening and closing of the linear type shutter valve 25.
And a second predetermined opening line L7 on the low opening side, cold EGR is performed on the higher load side than line L7, hot EGR is performed on the lower load side than line L6, and between both lines L6 and L7. Cold EGR in the lap
Since the combined use of hot EGR and, in particular, while compensating for the lack of the EGR amount in the lap portion, suppression of an increase in HC emissions, there is an effect that can be achieved and reduction of deterioration suppression and RawNOx the lean limit .

That is, the above-mentioned lap portion (for example, A / F =
In a portion corresponding to 16 to 20), if only hot EGR is performed, the EGR amount becomes insufficient, and if only cold EGR is performed, the gas temperature is already low, which leads to deterioration of the lean limit and increase of RawHC. By using the cold EGR gas together, such a problem can be avoided. In addition, in other respects, the same operation and effect as those of the previous embodiment are obtained.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIGS. However, also in this embodiment, FIG.
The circuit device of is used. The fifth map M5 shown in FIG.
Represents the engine speed Ne on the horizontal axis and the load CE = on the vertical axis.
By taking Q / Ne, a set air-fuel ratio line L8 of λ ≧ 1 (λ = 1 in this embodiment) for switching between cold EGR and hot EGR is provided, and the lean side of this line L8 is in the hot EGR region. The cold side on the rich side
And the low load and low speed range is set to the EGR prohibition range as described above, and the engine speed Ne is set as shown in FIG.
The air-fuel ratio in each region according to
/ F = 16, A / F = 18, A / F = 20, A / F = 2
2, A / F = 24, and A / F = 26.

Here, the above-mentioned CPU 50 is at least on the low load side based on the output of the operating state detecting means (see steps S61 and S62 in the flowchart shown in FIG. 13) for detecting the operating state of the engine and the operating state detecting means. The air-fuel ratio A / F supplied to the engine is lean air-fuel ratio λ> 1
The air-fuel ratio control means for controlling the air-fuel ratio so that the air-fuel ratio and the operation state detection means (see steps S61 and S62) close the shutter valve 25 on the low load side while the high load On the side, the relatively low temperature EGR gas is recirculated on the rich air-fuel ratio side from the first control means (the CPU 50 itself in this embodiment) for opening the shutter valve 25 and the set air-fuel ratio line L8 described above. Cold E
While performing GR, second control means for performing hot EGR in which EGR gas having a relatively high temperature is circulated on the lean air-fuel ratio side of the above-described set air-fuel ratio line L8 (each step S66, S67 in the flowchart shown in FIG. 13). See also).

The operation of the exhaust gas recirculation system for an engine with a supercharger (embodiment corresponding to claim 5 ) thus constructed will be described in detail below with reference to the flow chart shown in FIG.

In the first step S61, the CPU 50 executes the reading of various necessary signal inputs such as the intake air amount Q, the engine speed Ne, the air-fuel ratio A / F, etc., and in the next second step S62, the CPU 50 executes the CE. The load CE is calculated by the calculation formula = Q / Ne.

Next, in a third step S63, the CPU 50 indicates that the current engine operating state is the fifth map M5 shown in FIG.
It is determined whether or not the set air-fuel ratio line L8 is less than or equal to L8, and when the YES determination is less than or equal to L8, the process proceeds to the next fourth step S64, while when the NO determination is greater than or equal to L8, another seventh step S6 is performed.
Move to 7.

In the above-mentioned fourth step S64, the CPU 50
Is the fifth map M showing the current engine operating state shown in FIG.
No. 8 EGR prohibition region is determined. If YES is determined in the region, the process proceeds to the next fifth step S65, and N outside the region is determined.
When the O determination is made, the process proceeds to another sixth step S66.

In the above-mentioned fifth step S65, the CPU 50
Closes the first and second EGR valves 37 and 41,
The EGR gas recirculation is prohibited and the above-described sixth step S66 is performed.
Then, the CPU 50 opens the first EGR valve 37 to recirculate the relatively high temperature EGR gas from the external hot EGR system passage 36 to the intake system, while in the seventh step S67 described above, C
The PU 50 opens the second EGR valve 38 to open the external cold E
Relatively low temperature EGR gas from the GR system passage 42 is recirculated to the intake system.

That is, when the in-cylinder flow control is performed by the VVT 47 or the like without using the shutter valve 25 and the stratification (lean burn) is achieved, the NOx emission amount is reduced by the hot EGR. This hot EGR has a high gas temperature and good re-combustibility, and since the vaporization and atomization of the fuel are also good, it is possible to suppress an increase in the amount of HC emissions. In addition, the EGR effect of recirculating the EGR gas causes There is an effect that the pumping loss can be reduced.

On the other hand, when the air-fuel ratio is richer than λ ≧ 1 and high charging efficiency and high torque are achieved by supercharging by the Rismolum compressor 9, the cylinder is owing to the high supercharging of the Rismolum compressor 9 of the Miller cycle engine. The cold EGR suppresses an increase in the internal temperature, a large heat load, and a tendency for knocking to occur. In other words, since the cold EGR has a low gas temperature, the combustion speed can be slowed down, and the in-cylinder temperature can be lowered to prevent knocking. in addition,
Cold E while reducing NOx by EGR effect
Since the exhaust gas temperature can be reduced by the circulation of the GR gas, there is an effect that the thermal deterioration of the catalyst can be suppressed.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described with reference to FIGS. However, also in this embodiment, FIG.
The circuit device of is used. The sixth map M6 shown in FIG.
Represents the engine speed Ne on the horizontal axis and the load CE = on the vertical axis.
By taking Q / Ne, a predetermined lean side air-fuel ratio line L9 of λ> 1 for switching between cold EGR and hot EGR is provided, and the lean side from this line L9 is hot EG.
In the R region, the rich side is set to the cold EGR region, and the low load and low rotation region is set to the EGR prohibition region as described above. Further, as shown in FIG. 14, in each region corresponding to the engine speed Ne and the load. The air-fuel ratio is A / F = 16, A /
F = 18, A / F = 20, A / F = 22, A / F = 2
4 and A / F = 26.

Here, the above-mentioned CPU 50 at least on the low load side based on the output of the operating state detecting means (see steps S71 and S72 in the flowchart shown in FIG. 15) for detecting the operating state of the engine and the operating state detecting means. The air-fuel ratio A / F supplied to the engine is lean air-fuel ratio λ> 1
The air-fuel ratio control means for controlling the air-fuel ratio so that the air-fuel ratio and the operation state detection means (see steps S7 and S72) are used to close the shutter valve 25 on the low load side while the high load On the side, the first control means (the CPU 50 itself in this embodiment) for opening the shutter valve 25 described above and the EGR gas having a relatively low temperature on the rich air-fuel ratio side of the predetermined lean side air-fuel ratio line L9 recirculate. While performing the cold EGR that is performed, the EGR having a relatively high temperature on the lean air-fuel ratio side from the set lean-side air-fuel ratio line L9 described above.
Second control means for performing hot EGR in which gas is recirculated (each step S76, S in the flowchart shown in FIG. 15)
(See 77).

The operation of the exhaust gas recirculation system for an engine with a supercharger (embodiment corresponding to claim 6 ) thus constructed will be described in detail below with reference to the flow chart shown in FIG.

In the first step S71, the CPU 50 executes reading of various necessary signal inputs such as the intake air amount Q, the engine speed Ne, the air-fuel ratio A / F, etc., and in the next second step S72, the CPU 50 executes the CE. The load CE is calculated by the calculation formula = Q / Ne.

Next, in a third step S73, the CPU 50 determines that the current engine operating state is the sixth map M6 shown in FIG.
Of the lean side air-fuel ratio line L9 or more is determined,
While the determination of YES at L9 following the process proceeds to a fourth step S74 follows, shifts to another seventh step S77 in determination of NO on L9 than.

In the above-mentioned fourth step S74, the CPU 50
Is the sixth map M in which the current engine operating state is shown in FIG.
It is determined whether or not it is the EGR prohibition region of No. 6, and if YES is determined in the region, the process proceeds to the next fifth step, and if NO is determined outside the region, the process proceeds to another sixth step S76.

In the above-mentioned fifth step S75, the CPU 50
Closes the first and second EGR valves 37 and 41,
The EGR gas recirculation is prohibited, and the above-described sixth step S76 is performed.
Then, the CPU 50 opens the first EGR valve 37 to recirculate the relatively high temperature EGR gas from the external hot EGR system passage 36 to the intake system, while in the seventh step S77 described above, C
The PU 50 opens the second EGR valve 38 to open the external cold E
Relatively low temperature EGR gas from the GR system passage 42 is recirculated to the intake system.

That is, the above sixth setting means (see sixth map M6) is provided with a predetermined lean side air-fuel ratio line L9 of λ> 1 for switching between cold EGR and hot EGR, and second control means (each). In steps S76 and S77), cold EGR is performed on the rich air-fuel ratio side of the predetermined lean side air-fuel ratio line L9, and hot EGR is performed on the lean air-fuel ratio side of the predetermined lean side air-fuel ratio line L9.

In short, the cold EGR is performed in a region where relatively low speed knocking such as low / medium speed / high load is likely to occur between the line L8 of λ = 1 and the predetermined lean side air-fuel ratio line L9 of λ> 1. Therefore, there is an effect that such low speed knocking can be suppressed.
In other respects, the same operation and effect as those of the fifth embodiment are obtained.

(Seventh Embodiment) Next, a seventh embodiment of the present invention will be described with reference to FIGS. However, the circuit device of FIGS. 1 and 2 is also used in this embodiment. Further, in the seventh map M7 shown in FIG. 16, the horizontal axis represents the engine speed Ne and the vertical axis represents the load CE = Q.
/ Ne to set a rich first predetermined air-fuel ratio line L10 and a lean second predetermined air-fuel ratio line L11 for switching between cold EGR and hot EGR in a region where the theoretical air-fuel ratio λ = 1 or less. The lean air-fuel ratio side of the line L10 is set in the hot EGR region, the rich air-fuel ratio side of the line L11 is set in the cold EGR region, and the lap region between the lines L10, L11 is set in the hot EGR region. The seventh setting means sets the region and the cold EGR together and sets the low rotation and low load side to the EGR prohibition region.

The air-fuel ratio in each region is A / F = 16, A corresponding to the engine speed Ne and the load.
/ F18, A / F = 20, A / F = 22, A / F = 2
4 and A / F = 26 are the same as in the previous maps M5 and M6.

Here, the above-mentioned CPU 50 operates on the low load side based on the output of the operating state detecting means (see steps S81 and S82 in the flowchart shown in FIG. 17) for detecting the operating state of the engine and the operating state detecting means. At least the air-fuel ratio A / F supplied to the engine is lean air-fuel ratio λ>
Air-fuel ratio control means for controlling the air-fuel ratio so that it becomes 1.
The above-mentioned operating state detecting means (see steps S81 and S82).
The first control means (the CPU 50 itself in this embodiment) that closes the shutter valve 25 of the above ) and opens the above-mentioned shutter valve 25 on the high load side, and the second predetermined air-fuel ratio line L11. Cold EGR on the rich air-fuel ratio side
On the other hand, it also serves as second control means (see steps S86, S88, S89 shown in FIG. 17) for performing hot EGR on the lean air-fuel ratio side of the first predetermined air-fuel ratio line L10.

The operation of the exhaust gas recirculation system for an engine with a supercharger (embodiment corresponding to claim 7 ) thus constructed is shown in FIG.
This will be described in detail below with reference to the flowchart shown in FIG.

In the first step S81, the CPU 50 executes the reading of various necessary signal inputs such as the intake air amount Q engine speed Ne, the air-fuel ratio A / F, etc., and the following second step S81.
At 82, the CPU 50 calculates the load CE by the calculation expression CE = Q / Ne.

Next, in a third step S83, the CPU 50 determines that the current engine operating state is the seventh map M7 shown in FIG.
Line L11 or more, the process proceeds to the next fourth step S84 when the NO determination is made, while the process proceeds to another seventh step S87 when the YES determination is made.

In the above-mentioned fourth step S84, the CPU 50
Determines whether or not it is within the EFR prohibited area, and moves to the next fifth step S85 when the YES determination is made, and moves to another sixth step S86 when the NO determination is made.

In the above-mentioned fifth step S85, the CPU 50
Closes the first and second EGR valves 37 and 41,
The EGR gas recirculation is prohibited, and in the sixth step S86 described above, the CPU 50 opens the first EGR valve 37 to recirculate the relatively high temperature EGR gas from the external hot EGR system passage 36 to the intake system.

By the way, in the above-mentioned seventh step S87,
The CPU 50 determines whether or not it is within the lap area in the seventh map M7 of FIG. 16, and moves to the next eighth step S88 when the YES determination is made, and moves to another ninth step S89 when the NO determination is made.

In the above-mentioned eighth step S88, the CPU 50
Opens both the first and second EGR valves 37 and 38 to allow the relatively high temperature EGR from the external hot EGR system path 36.
Both the gas and the relatively low temperature EGR gas from the external cold EGR system passage 42 are recirculated to the intake system.

In the ninth step S89 described above, the CPU
Reference numeral 50 indicates the external cold EGR by opening the second EGR valve 38.
Relatively low temperature EGR gas from the system passage 42 is recirculated to the intake system. That is, the above-mentioned seventh setting means (seventh map M7
(See), a rich predetermined first air-fuel ratio line L10 and a lean second predetermined air-fuel ratio line L11 are provided for switching between cold EGR and hot EGR in a region where the theoretical air-fuel ratio λ = 1 or less. 2 control means (each step S8
6, S88, S89) performs cold EGR on the rich air-fuel ratio side of the second predetermined air-fuel ratio line L11 and performs hot EGR on the lean air-fuel ratio side of the first predetermined air-fuel ratio line L10.

In short, since cold EGR and hot EGR are used together in the lap portion between the first and second predetermined air-fuel ratio lines L10 and L11 described above, in particular , the lap portion is compensated for the lack of the EGR amount. , Suppression of increase in HC emissions, suppression of deterioration of lean limit and Raw
There is an effect that reduction of NOx can be achieved.

Incidentally, the above-mentioned lap portion (for example, A / F = 1)
In the portion corresponding to 6 to 20), if only hot EGR is performed , the EGR amount becomes insufficient, and if only cold EGR is performed , the burned gas temperature is low, which leads to deterioration of the lean limit and increase of RawHC. By using the EGR gas and the cold EGR gas together, such a problem can be avoided.

In the correspondence between the configuration of the present invention and the above-described embodiment, the supercharger of the present invention corresponds to the Rishorum compressor 9 of the embodiment, and hereinafter, similarly, the engine corresponds to the V-type 6-cylinder engine, The primary intake port corresponds to P port 24, and the secondary intake port is S port 2
3, the external EGR means corresponds to the external hot EGR system path 36 and the external cold EGR system path 42, and the operation state detecting means corresponds to the steps S1, S2, S11, S1.
2, S21, S22, S41, S42, S61, S6
2, S71, S72, S81, S82, and the first control means includes steps S6, S7, S16, S17,
Corresponding to S31, S33, S53, S55, hot EG
The R means includes steps S6, S16, S26, S32,
Corresponding to steps S49 and S54, the cold EGR means includes steps S7, S17, S27, S34, S48 and S56.
The second control means corresponds to the steps S66 and S6.
7, S76, S77, S86, S88, S89, the first setting means corresponds to the first map M1, the second setting means corresponds to the second map M2, and the third setting means
Corresponding to the third map M3, the fourth setting means corresponds to the fourth map M4, the fifth setting means corresponds to the fifth map M5, the sixth setting means corresponds to the sixth map M6, The seventh setting means corresponds to the seventh map M7, but the present invention is not limited to the configuration of the above-described embodiment.

[Brief description of drawings]

FIG. 1 is a system diagram showing an exhaust gas recirculation system for a supercharged engine according to the present invention.

FIG. 2 is a control circuit block diagram.

FIG. 3 is an explanatory diagram of a first map.

FIG. 4 is a flowchart showing a first embodiment of EGR switching control.

FIG. 5 is a characteristic diagram showing changes in NOx and HC emissions with respect to EGR flat.

FIG. 6 is an explanatory diagram of a second map.

FIG. 7 is a flowchart showing a second embodiment of EGR switching control.

FIG. 8 is an explanatory diagram of a third map.

FIG. 9 is a flowchart showing a third embodiment of EGR switching control.

FIG. 10 is an explanatory diagram of a fourth map.

FIG. 11 is a flowchart showing a fourth embodiment of EGR switching control.

FIG. 12 is an explanatory diagram of a fifth map.

FIG. 13 is a flowchart showing a fifth embodiment of EGR switching control.

FIG. 14 is an explanatory diagram of a sixth map.

FIG. 15 is a flowchart showing a sixth embodiment of EGR switching control.

FIG. 16 is an explanatory diagram of a seventh map.

FIG. 17 is a flowchart showing a seventh embodiment of EGR switching control.

FIG. 18 is a complaint correspondence diagram.

FIG. 19 is a characteristic diagram showing the relationship between NOx and HC emissions with respect to the air-fuel ratio.

[Explanation of symbols]

9 ... Risholum compressor 23 ... S port 24 ... P port 25 ... Shutter valve 36 ... External hot EGR system path 42 ... External cold EGR system path S1, S2, S11, S12, S21, S22, S4
1, S42 ... Driving state detecting means S61, S62, S71, S72, S81, S82 ... Driving state detecting means S6, S7, S16, S17, S31, S33, S5
3, S55 ... First control means S6, S16, S26, S32, S49, S54 ... Hot EGR means S7, S17, S27, S34, S34, S56 ... Cold EGR means S66, S67, S76, S77, S86, S88 , S
89 ... Second control means M1 ... First setting means M2 ... Second setting means M3 ... Third setting means M4 ... Fourth setting means M5 ... Fifth setting means M6 ... Sixth setting means M7 ... Seventh setting means

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI F02M 25/07 F02M 25/07 580E F02B 17/00 F02B 17/00 L 31/00 331 31/00 331A 31/02 31/02 J F02D 43/00 301 F02D 43/00 301E 301N 301R F02M 69/00 360 F02M 69/00 360C (56) Reference JP-A-5-86949 (JP, A) JP-A-3-237216 (JP, A) JP-A-5-86945 (JP, A) JP-A-61-169616 (JP, A) Actual development 5-57319 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02M 25/07 550 F02M 25/07 570 F02M 25/07 580 F02B 17/00 F02B 31/00 331 F02B 31/02 F02D 43/00 301 F02M 69/00 360

Claims (9)

(57) [Claims] 1. A primary intake port and a secondary intake port provided for a single cylinder, a shutter valve for in-cylinder flow enhancement provided in the secondary intake port, and a supercharger for supercharging intake air. And an operating state detecting means for detecting the operating state of the engine, and based on the output of the operating state detecting means, the air-fuel ratio is controlled so that at least the air-fuel ratio supplied to the engine is a lean air-fuel ratio on the low load side. Supercharging including air-fuel ratio control means and first control means for closing the shutter valve on the low load side while opening the shutter valve on the high load side based on the output of the operating state detection means. An exhaust gas recirculation device for an engine with a machine, comprising hot EGR means for recirculating relatively high temperature EGR gas in a shutter valve closed region in response to opening and closing of the shutter valve, and a shut-off device. In the valve opening region, cold EGR means for circulating relatively low-temperature EGR gas is provided , and the shutter valve is constituted by an ON / OFF type opening / closing valve.
On the other hand, the set air-fuel ratio line of λ = 1 for switching the shutter valve opening / closing
The first control means is provided, and the first control means controls the λ> 1 range below the set air-fuel ratio.
One for performing hot EGR by fully closing the shutter valve.
On the other hand, the shutter valve is operated in the range of λ ≦ 1 above the set air-fuel ratio
Of a supercharged engine that performs cold EGR when it is fully opened.
Exhaust gas recirculation device. 2. A primary provided for a single cylinder
Intake port and secondary intake port, and for in-cylinder flow enhancement provided in the secondary intake port
Shutter valve, a supercharger for supercharging intake air, a rotation state detecting means for detecting the operating state of the engine, and a low load side based on the output of the operating state detecting means.
Even if the air-fuel ratio supplied to the engine is lean
The air-fuel ratio control means for controlling the air-fuel ratio so that
Based on the output of the rotation state detection means, on the low load side
The shutter valve is closed on the high load side while the shutter valve is closed.
Of a supercharged engine equipped with a first control means for opening
An exhaust gas recirculation device, which corresponds to the opening and closing of the shutter valve in the shutter valve closed region.
Is a hot EGR hand that recirculates relatively high temperature EGR gas.
Recirculation of relatively low temperature EGR gas in the stage and in the shutter valve closed region
And a cold EGR means for controlling the shutter valve to be an ON / OFF type opening / closing valve.
On the other hand, the set air-fuel ratio in the lean air-fuel ratio range for switching the shutter valve opening / closing
A second setting means having a ratio line is provided, and the first control means has a lower load than the set air-fuel ratio line.
Side, fully close the shutter valve and perform hot GER.
On the other hand, on the higher load side than the set air-fuel ratio line,
With supercharger that performs cold EGR by fully opening the valve
Exhaust gas recirculation system for engines. 3. A primary provided for a single cylinder
Intake port and secondary intake port, and for in-cylinder flow enhancement provided in the secondary intake port
Shutter valve, a supercharger for supercharging intake air, a rotation state detecting means for detecting the operating state of the engine, and a low load side based on the output of the operating state detecting means.
Even if the air- fuel ratio supplied to the engine is lean
The air-fuel ratio control means for controlling the air-fuel ratio so that
Based on the output of the rotation state detection means, on the low load side
The shutter valve is closed on the high load side while the shutter valve is closed.
Of a supercharged engine equipped with a first control means for opening
An exhaust gas recirculation device, which corresponds to the opening and closing of the shutter valve in the shutter valve closed region.
Is a hot EGR hand that recirculates relatively high temperature EGR gas.
Recirculation of relatively low temperature EGR gas in the stage and in the shutter valve closed region
It is equipped with cold EGR means for controlling the opening of the shutter valve from fully closed to fully opened.
While it is composed of a linear type on-off valve that can be adjusted manually, it has a predetermined opening degree between the fully open and fully closed shutter valves.
Setting line for switching between hot EGR and cold EGR
The third setting means with a
Cold EGR is carried out on the cargo side, and it is lower than the above setting line.
Exhaust of a supercharged engine that performs hot EGR on the load side
Reflux device. 4. A primary provided for a single cylinder
Intake port and secondary intake port, and for in-cylinder flow enhancement provided in the secondary intake port
Shutter valve, a supercharger for supercharging intake air, a rotation state detecting means for detecting the operating state of the engine, and a low load side based on the output of the operating state detecting means.
Even if the air-fuel ratio supplied to the engine is lean
The air-fuel ratio control means for controlling the air-fuel ratio so that
Based on the output of the rotation state detection means, on the low load side
The shutter valve is closed on the high load side while the shutter valve is closed.
Of a supercharged engine equipped with a first control means for opening
An exhaust gas recirculation device, which corresponds to the opening and closing of the shutter valve in the shutter valve closed region.
Is a hot EGR hand that recirculates relatively high temperature EGR gas.
Recirculation of relatively low temperature EGR gas in the stage and in the shutter valve closed region
It is equipped with cold EGR means for controlling the opening of the shutter valve from fully closed to fully opened.
While it is composed of a linear type open / close valve that can be adjusted manually, the high opening side of the shutter valve between full open and closed.
The first predetermined opening line and the second predetermined opening line on the low opening side
Mochi, 4th setting means having a wrap between both lines
On the higher load side than the second predetermined opening line, cold E
Perform GR, and on the low load side from the first predetermined opening line
Exhaust gas recirculation equipment for turbocharged engines that perform hot EGR
Place 5. A primary provided for a single cylinder
Intake port and secondary intake port, and for in-cylinder flow enhancement provided in the secondary intake port
Shutter valve, a supercharger for supercharging intake air, a rotation state detecting means for detecting the operating state of the engine, and a low load side based on the output of the operating state detecting means.
Even if the air-fuel ratio supplied to the engine is lean
The air-fuel ratio control means for controlling the air-fuel ratio so that
Based on the output of the rotation state detection means, on the low load side
The shutter valve is closed on the high load side while the shutter valve is closed.
Of a supercharged engine equipped with a first control means for opening
An exhaust gas recirculation system, in which λ ≧ 1 for switching between cold EGR and hot EGR.
A fifth setting means having a constant air-fuel ratio line is provided, and is relatively lower on the rich air-fuel ratio side than the set air-fuel ratio line.
Performing cold EGR in which warm EGR gas is recirculated
On the other hand, relative to the lean air-fuel ratio side from the above set air-fuel ratio line
Perform hot EGR in which high temperature EGR gas is recirculated to
Exhaust gas recirculation device for engine with supercharger having second control means
Place 6. For switching between cold EGR and hot EGR
6th setting with a predetermined lean side air-fuel ratio line of λ> 1
Means is provided to connect the rich air-fuel ratio side from the predetermined lean side air-fuel ratio line.
While performing the field EGR, hold on the lean air-fuel ratio side from the set lean-side air-fuel ratio line.
Of the supercharged engine according to claim 5, wherein
Exhaust gas recirculation device. 7. Cold EGR in a region below the stoichiometric air-fuel ratio
The first predetermined air-fuel ratio ratio on the rich side for switching to hot EGR
It has a second specified air-fuel ratio line on the in and lean sides,
7th setting means having a lap portion between the
Cold EGR on the rich air-fuel ratio side from the specified air-fuel ratio line
While performing the lean air-conditioning from the first predetermined air-fuel ratio line
The supercharger according to claim 5, wherein hot EGR is performed on the fuel ratio side.
Exhaust gas recirculation system for engines. 8. The cold EGR is located downstream of the catalytic converter.
The external EGR means that recirculates the relatively low temperature EGR gas
Set, the hot EGR is relatively high near the exhaust port.
A contract set as an external EGR means for recirculating warm EGR gas
Exhaust gas return of the engine with a supercharger according to any one of claims 1 to 5.
Flow device. 9. The hot EGR is an intake / exhaust valve overlap.
Internal EGR that recirculates internal residual gas to the intake side by
The cold EGR is set to a relatively low temperature E of the exhaust system.
6. An external EGR that recirculates GR gas is set.
The exhaust gas recirculation device for an engine with a supercharger according to any one of 1.