JP2000045878A - Exhaust recirculation device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the level of difference in concentration of EGR gas between cylinders. SOLUTION: Two exhaust introduction ports 31a, 32a are opened to an intake passage 10 common for a plurality of engine cylinders, in series in a flowing direction of intake air. The volumes of EGR gas introduced through the introduction ports 31a, 32a are periodically changed since the pressure differential between exhaust gas and intake air periodically varies. In the intake passage 10, a part of EGR gas having a high (low) at the position of the introduction port 31a merges into or interfered with a part of EGR gas having a low (high) concentration at the position of the introduction port 32a, and accordingly, the variation in the concentration of EGR gas becomes smaller downstream of the introduction port 32a. In order to effect the above-mentioned interference, the volume V of the intake air passage in a part having a distance L between the introduction ports 31a, 32a is set to be larger than n∼a+1/3α but smaller than n∼a+2/3α where α is an intake air charge volume per engine cylinder (the period of variation in the concentration of EGR gas between the introduction ports 31a, 32a is shifted by 1/3 to 2/3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust gas recirculation device for an engine.

[0002] In engines, especially in diesel engines for automobiles, it is desired to greatly reduce NOx and particulate components. Therefore, basically N
While performing a large quantity EGR for O _X reduction, so that the actual air-fuel ratio becomes the target air-fuel ratio, controlling the EGR gas amount in accordance with the actual intake air amount and the fuel injection quantity (EGR
(Opening control of a valve) has been proposed (JP-A-8-14).
No. 4867, Japanese Patent Publication No. 3-19376).
To explain this point in detail, the richer the air-fuel ratio, the more NO _x
Is reduced, while the particulate component is increased. Therefore, the target air-fuel ratio is set so as to sufficiently satisfy both reductions. The control of the EGR gas amount is performed so that the amount of fresh air actually supplied into the cylinder corresponds to the target air-fuel ratio.

[0003]

The exhaust gas for EGR is introduced into the intake passage on the basis of the differential pressure between the exhaust pressure and the intake pressure. However, since each of the exhaust pressure and the intake pressure has a pulsation, The differential pressure also has a pulsation. As a result, the concentration of the exhaust gas introduced into the intake passage, that is, the concentration of the EGR gas, naturally has a fluctuation having a pulsation due to the pulsation of the differential pressure. Such a change in the EGR gas concentration causes a difference in the EGR gas concentration between the cylinders.

As described above, the difference in the EGR gas concentration between the cylinders due to the variation in the EGR gas concentration in the intake passage causes a difference in the combustibility and the exhaust gas component between the cylinders. It is not preferable. In particular, when the EGR gas amount is controlled to be the target air-fuel ratio as described above, a situation occurs in which the actual air-fuel ratio between the cylinders greatly deviates from the target air-fuel ratio.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust gas recirculation device for an engine capable of greatly reducing the difference in EGR gas concentration between cylinders. It is in.

[0006]

In order to achieve the above object, the present invention has a first solution as follows. That is, as described in claim 1 of the claims, the first EGR gas inlet is opened in the intake passage for supplying intake air to the plurality of cylinders, and the intake passage is located downstream of the intake passage in the intake flow direction. Second EGR on the side
A gas inlet is opened, and the distance between the first EGR gas inlet and the second EGR gas inlet in the direction of the intake passage is determined by the change in the EGR gas concentration at the first EGR gas inlet and the second EGR gas.
Due to interference with fluctuations in the EGR gas concentration at the EGR gas inlet, E at the downstream side of the second EGR gas inlet is reduced.
It is set so that the fluctuation of the GR gas concentration is reduced. Preferred embodiments based on the first solution are as described in claims 2 and 17 and the following claims.

In order to achieve the above object, the present invention is as follows as a second solution. That is, as described in claim 3 of the claims,

Fuel control means for controlling the amount of fuel supplied to the engine, intake air amount detecting means for detecting the amount of intake air, an EGR valve for adjusting the amount of EGR gas, and actual supply to the engine by the fuel control means EGR control means for controlling the EGR valve such that an actual air-fuel ratio obtained based on the measured fuel amount and the actual intake air amount detected by the intake air amount detection means becomes a predetermined target air-fuel ratio. In the exhaust gas recirculation system for an engine provided with the first passage, an intake passage for supplying intake air to a plurality of cylinders is provided.
The EGR gas inlet is opened and the second EGR gas inlet is opened downstream of the intake passage in the direction of intake air flow, and the center between the center of the first EGR gas inlet and the center of the second EGR gas inlet is opened. Assuming that the inter-intake passage volume is V, the intake filling amount of one cylinder is α, and n is an integer including 0, it is set so as to satisfy the relational expression of n × α + α / 3 ≦ V ≦ n × α + 2α / 3. That's right. Preferred embodiments based on the second solution are as described in Claims 4 and the following claims.

[0009]

According to the first aspect of the present invention, the EGR gas downstream from the second EGR gas inlet is provided by an interference effect utilizing the respective fluctuations in the amount of the EGR gas introduced from both EGR gas inlets into the intake passage. The variation in the concentration can be reduced, and the difference in the EGR gas concentration between the cylinders can be reduced. According to the second aspect, it is preferable to accurately control each cylinder so that the actual air-fuel ratio becomes the target air-fuel ratio.

According to the third aspect, a more specific solution for obtaining the effect corresponding to the second aspect is provided. According to claim 4, a more specific solution than claim 3 is provided.

According to the fifth aspect, the amount of EGR gas introduced from both EGR gas inlets is made substantially equal, which is preferable in that fluctuations in EGR gas concentration utilizing interference are sufficiently reduced. According to the sixth aspect, the adjustment of the EGR gas amount from both the EGR gas inlets can be performed only by controlling one EGR valve. According to the seventh aspect, the EGR gas is more easily introduced on the downstream side than on the upstream side of the intake passage, but by a simple method of setting the effective opening area of the two EGR gas introduction ports to be large or small. These two E
This is preferable in that the amount of EGR gas introduced from the GR gas inlet is made substantially equal and interference is utilized to sufficiently reduce fluctuations in EGR gas concentration. Further, by making the pipe diameters of the two connection pipes equal to each other, it is not necessary to manage the connection pipes according to the pipe diameters, and it is possible to prevent the connection pipe from being connected incorrectly.

According to the eighth aspect, a control valve is provided for the second EGR gas inlet on the downstream side where EGR gas is easily introduced, which is preferable in that the amount of EGR gas can be reduced with good response. According to the ninth aspect, it is preferable to reduce the EGR gas responsively when the engine is accelerated, to sufficiently satisfy the acceleration performance, and to prevent the increase in the particulate component during the acceleration responsively.

According to the tenth aspect, the difference in the EGR gas concentration between the cylinders can be further reduced by using the surge tank serving as the volume expansion chamber. According to claim 11, EGR introduced from two EGR gas inlets
The uneven distribution of the gas in the intake passage is set at substantially the same position in the circumferential direction of the intake passage, that is, the EGR gas introduced from the two EGR gas introduction ports is sufficiently mixed with each other to reduce the fluctuation of the EGR gas concentration. This is preferable in terms of reduction.

According to the twelfth aspect, while controlling only one EGR valve for air-fuel ratio control and controlling a control valve having a small lift amount and excellent responsiveness, the total EGR gas amount can be reduced. It can be changed responsively.
According to the thirteenth aspect, the same effect as the effect corresponding to the ninth aspect can be obtained.

According to the fourteenth aspect, it is preferable to minimize the fluctuation of the exhaust pressure to further reduce the fluctuation of the EGR gas concentration. According to the fifteenth aspect, the pressure fluctuation in the EGR passage is reduced as much as possible by utilizing the large volume of the EGR cooler, which is preferable for further reducing the fluctuation of the EGR gas concentration. According to the sixteenth aspect, the volume of the whole EGR passage is substantially greatly expanded while reducing the fluctuation of the pressure in the EGR passage by using the resonance chamber to further reduce the fluctuation of the EGR gas concentration. This is preferable in that the EGR gas amount is prevented from changing and the EGR gas amount is changed with good response.

According to the seventeenth aspect, in the direct injection diesel engine which is advantageous in improving fuel efficiency, it is possible to reduce the difference in the EGR gas concentration for each cylinder. According to the eighteenth aspect, it is possible to accurately control the fuel injection timing and the fuel injection amount while performing high-pressure fuel injection. According to the nineteenth aspect, it is preferable to effectively utilize the interference of the EGR gas introduced from the two EGR gas introduction ports to more sufficiently prevent the fluctuation of the EGR gas concentration.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes an engine,
2 is a combustion chamber, 3 is a piston, 4 is an intake port, 5 is an intake valve, 6 is an exhaust port, and 7 is an exhaust valve. In the embodiment, the engine 1 is an in-line four-cylinder four-cycle direct injection diesel engine. Therefore, a fuel injection valve 8 for directly injecting fuel into the combustion chamber 2 is provided. The fuel injection valves 8 of the respective cylinders are independently connected to a common rail 9, and the high pressure fuel from the fuel injection pump P is constantly stored in the common rail 9.
The fuel injection valve 8 has an electronically controlled valve opening timing and valve opening amount. The fuel injection timing is controlled by controlling the valve opening timing, and the fuel injection timing is controlled by controlling the valve opening amount. The amount is controlled. The fuel injection amount is determined using, for example, an engine speed and an accelerator opening as an engine load as parameters.

Reference numeral 10 denotes an intake passage.
, The air cleaner 1 in order from the upstream side to the downstream side.
1. Air flow meter 1 as intake air amount detecting means
2. The compressor wheel 1 of the turbocharger 13
3a, an intercooler 14, and a surge tank 15 are connected. The surge tank 15 and each of the cylinders (the intake port 4) are connected by independent independent intake passages 16. As described above, the portion of the intake passage 10 from the air cleaner 11 to the surge tank 15 is a single common intake passage common to each cylinder, that is, a plurality of cylinders. Independent intake passages (branch intake passages) are provided independently for each cylinder.

Reference numeral 20 denotes an exhaust passage. The exhaust passage 10 has an exhaust turbocharger 13 sequentially from its upstream side.
And an exhaust gas purification catalyst (an oxidation catalyst in the embodiment) 21 are connected. Exhaust passage 10
Among them, one EGR passage (common EGR passage) 30 is led upstream of the turbine wheel 13b, that is, on the engine 1 side. The EGR passage 30 is branched into two at the downstream side, and each of the branched EGR passages 31 and 32 is connected to an EGR gas inlet 31a or 32a.
The opening 10 is provided in an intake passage between the intercooler 14 and the surge tank 15. Branch EGR passage 3
In the common EGR passage 30, which is located on the upstream side of the first and the second 32,
An EGR cooler 33, a resonance chamber 35, and an EGR valve 34 are sequentially connected from the exhaust passage 20 side.

As shown in FIG. 2, the portion of the intake passage 10 where the EGR gas inlets 31a and 32a are open is substantially straight as a whole (completely straight in the embodiment).
Is formed. Also, both EGR gas inlets 31a,
32a are formed at substantially the same position in the circumferential direction of the intake passage 10 (completely the same position in the embodiment). That is, the EGR gas introduced from the upstream EGR gas inlet 31a is sufficiently mixed with the EGR gas introduced from the downstream EGR gas inlet 32a.

FIG. 2 shows details of the branch EGR passages 31, 32. In FIG. 2, the EGR gas inlet 3
1 a and 32 a are formed as openings in the pipe wall of the intake passage 10. The connecting pipe 31A is connected to the inlet 31a (32a) by using the connecting members 41, 42 (44, 45).
(32A), the branch EGR passage 31
Alternatively, 32 is configured. That is, a cylindrical connection flange member 41 as a connection member is screwed to the female screw portion 40 formed on the inner periphery of the introduction port 31a,
Male thread portion 41a formed on this connection flange member 41
The connection pipe 31 </ b> A is connected to the connection flange member 41 by the connection nut member 42 screwed into the connection pipe 31.
Similarly, a cylindrical connection flange member 44 as a connection member is screwed into the female screw portion 43 formed on the inner periphery of the introduction port 32a, and the male screw portion 44a formed on the connection flange member 44 is screwed. Connection nut member 45 screwed
Thereby, the connection pipe 31B is connected to the connection flange member 44.
It is connected to the.

The effective opening area of the downstream EGR gas inlet 32a is set smaller than the effective opening area of the upstream EGR gas inlet 31a. In addition, both connecting pipes 31
The pipe diameters of A and 32A are equal to each other. Thereby, EG from both EGR gas introduction ports 31a and 32a is
The R gas introduction amounts are made substantially equal to each other. That is,
The pressure in the intake passage 10 becomes lower toward the downstream side, so that the EGR gas is easily introduced.
a (a downstream EGR passage 3 on the downstream side)
2), the amounts of EGR gas introduction from the two EGR gas introduction ports 31a and 32a are made substantially equal. The downstream connection pipe 32A
Is made smaller than the pipe diameter of the upstream connection pipe 31A, so that the passage resistance is made different and the inlet port 31a is formed.
It is also possible to make the amounts of EGR gas introduction from and 32a substantially equal.

FIG. 4A shows how the exhaust pressure and the intake pressure change (fluctuation, that is, pulsation), and FIG.
FIG. 7 shows a state in which the differential pressure between the exhaust pressure and the intake pressure that performs the suction action of the EGR gas changes. As described above, the differential pressure is periodically changed in accordance with the change in the crank angle. As a result, the amount of the EGR gas introduced from each of the EGR gas introduction ports 31a and 32a is also changed. Mouth 31
The EGR gas concentration in the intake passage 10 of the EGR gas immediately after being introduced from a and 32a also fluctuates considerably as shown in FIG.

At the time when the EGR gas concentration at the downstream EGR gas inlet 32a is high (high), the intake air having a low (thin) EGR gas concentration from the upstream EGR gas inlet 31a flows downstream. When the EG reaches the side inlet 31a, the EG downstream of the downstream inlet 32a.
The fluctuation of the R gas concentration becomes small as shown in FIG. This is the same when the intake air having a high EGR gas concentration from the upstream inlet 31a has just reached the downstream inlet 31a at the timing when the EGR gas concentration at the downstream inlet 32a is low. That is, by causing the fluctuation of the EGR gas concentration at the upstream inlet 31a and the fluctuation of the EGR gas concentration at the downstream EGR gas inlet 32a to interfere with each other, the EG at the downstream side of the downstream inlet 32a is interfered with.
It is possible to reduce the fluctuation of the R gas concentration.

In order to obtain the above-mentioned interference for reducing the EGR gas concentration fluctuation, E at both the inlets 31a and 32a is required.
What is necessary is just to shift the cycle of the fluctuation of the GR gas concentration. That is,
By setting the volume of the intake passage 10 corresponding to the distance L between the centers of the two inlets 31a and 32a to be in the range of 1/3 to 2/3 of the intake charge per cylinder, It is possible to sufficiently reduce the fluctuation of the EGR gas concentration due to the interference (if the shift of the cycle is too small, the effect of reducing the fluctuation of the EGR gas concentration will be small).
FIG. 7 shows the relationship between the period shift and the amplitude of the fluctuation of the EGR gas concentration. The deviation of the EGR gas concentration (the amplitude) ) Is reduced by half, the deviation is reduced from 1/3 period to 2/3.
What is necessary is just to set it in the range of a period.

The specific setting of the center-to-center distance L between the two inlets 31a and 32a, which is necessary to obtain a reduction in the fluctuation of the EGR gas concentration due to the interference described above, is as follows. First, the intake charge amount per cylinder of the engine 1 is defined as α (α =
Assuming that (stroke volume per cylinder × volume efficiency), in order to shift the cycle by 周期 cycle, the center-to-center volume V between the two inlets 31a and 32a satisfies the relation “V = α / 2”. In order to shift from 1/3 cycle to 2/3 cycle, "α /
3 ≦ V ≦ 2α / 3 ”.

Assuming that the diameter of the intake passage 10 is D, "V =
Since the (πD ^2/4) · L ", the shifted 1/2 period," L = 2α / πD ² "Tosureba well, 1/3 cycle -
To shift the 2/3 cycle, "4α / 3πD ² ≦ V ≦ 8α
/ 3πD ² ”. When such a relationship is satisfied, the center distance L is larger than the pipe diameter D in a normal engine.

The above description is for the case where the volume V is set to the minimum volume, and "n · α + α / 3 ≦ V ≦ n · α + 2α /
3], “n · α + 4α / 3πD ² ≦ V ≦ n · α + 8α /
3πD ² ”(n = 0, 1, 2, 3,...).
, With integers including zero).

Next, details of the EGR valve 3 will be described with reference to FIG. First, the EGR valve 3
Has a chamber 34b which is operated under negative pressure and is defined by a diaphragm 34a. As the negative pressure of the chamber 34b is larger, the distance between the valve body 34c connected to the diaphragm 34a and the valve seat 34e is increased (the degree of opening is larger).
By releasing the negative pressure of b, the return spring 3
The valve body 34c is seated on the valve seat 34e by 4d (closed).

The pressure in the chamber 34b is controlled by a pressure control valve 51. The pressure control valve 51 has a valve element 51a and a coil 51b for driving the valve element 51a. Valve element 51a
Adjusts the degree of communication between the negative pressure passage 39 extending from the vacuum pump 38 as a negative pressure source and the passage 38 extending from the chamber 34b (adjustment of the ratio of the passage 38 of the passage 38 to the atmosphere). A passage 53 for introducing atmospheric pressure or supercharging pressure is connected to the passage 38 connected to the chamber 34b,
An on-off valve (ON / OFF valve) 52 is connected to the passage 53. The effective opening area of the passage 38 on the pressure control valve 51 side of the passage 53 is sufficiently smaller than the effective opening area of the passage 53.

With the on-off valve 52 closed, the pressure control valve 5
By adjusting the degree of communication between the passages 38 and 39 by 1, the magnitude of the negative pressure in the chamber 34 b of the EGR valve 34 is adjusted, and the opening of the EGR valve 34 is adjusted. By opening the on-off valve 52 in a state where the communication between the passages 38 and 39 is interrupted by the pressure control valve 51, the chamber 34 is opened.
The pressure (pressure suppression) having a magnitude equal to or higher than the atmospheric pressure is introduced in response to b, and the EGR valve 34 is closed in response. The close of the EGR valve 34 with good response is performed, for example, when the engine is accelerated.

Here, the opening degree of the EGR valve 34 is determined by the actual air-fuel ratio of the intake air supplied to the engine, that is, the amount of intake air with respect to the amount of fuel injected from the fuel injection valve 8 (new intake air not including EGR gas). Amount) is the air-fuel ratio
Feedback control is performed so as to achieve a predetermined target air-fuel ratio. That is, since there is no throttle valve for adjusting the amount of intake air in the intake passage 10, the intake passage 1
By adjusting the EGR gas introduction amount to zero, the actual air-fuel ratio is controlled so as to become the target air-fuel ratio. In addition,
The target air-fuel ratio is mapped (stored) in advance using the operating state of the engine, for example, the engine speed and the accelerator opening as parameters.

FIG. 8 shows an example of a feedback control system for setting the actual air-fuel ratio to the target air-fuel ratio (a microcomputer for controlling the fuel injection amount and controlling the target air-fuel ratio). Control using data
A block diagram of an EGR valve control part for achieving the target air-fuel ratio among the functions of the above (a). That is, by the feedback control, the target opening degree (target opening area) of the EGR valve 34 is determined by the target intake air amount required for obtaining the target air-fuel ratio and the actual intake air amount detected by the air flow meter 12. Is calculated by PI control in accordance with the difference between. EGR valve 34 obtained by this PI control
The characteristics of the opening / closing speed of the EGR valve are set as shown in FIG. 9. As a result, as shown in FIG.
The speed ratio, which is the ratio of the R valve opening / closing speed, is substantially constant. However, since the relationship between the opening degree of the EGR valve 34 and the intake air amount (EGR gas amount) flowing therethrough is non-linear as shown in FIG. 11, the actual relationship between the opening degree of the EGR valve 34 and the above-mentioned speed ratio is obtained. The correspondence is as shown in FIG.

The control of the fuel injection amount from the fuel injection valve 8 and the control of the opening of the EGR valve 34 are performed by a control unit (controller, not shown) using a microcomputer.
This control unit constitutes a fuel control unit (control unit) and an EGR control unit (control unit) in the claims, and FIG. 8 is a block diagram showing the EGR control tasting. It is shown in a typical manner.

FIG. 13 shows another embodiment of the present invention, in which the same elements as those of the above embodiment are denoted by the same reference numerals, and the duplicated description thereof will be omitted. The same applies to the embodiment described above.) FIG. 13 corresponds to FIG. 2, and the difference from FIG.
The point is that an opening / closing control valve 55 (which can be considered as a second EGR valve) is connected to the R passage 32. The fully open lift amount of the control valve 55 is made smaller than the fully open lift amount of the negative pressure operated EGR valve 34, so that the responsiveness when fully closed is excellent. That is, the EGR gas amount can be reduced responsively by closing the control valve 55 responsively in a predetermined operating state, for example, during acceleration requiring a large engine output. Of course, at the time of acceleration, the EGR valve 34 can also be driven in the closing direction (or may be fully closed). However, the responsive valve closing action of the control valve 55 can reduce the EGR gas amount with good response.

FIG. 14 shows still another embodiment of the present invention, and corresponds to FIG. This figure 1
4, the exhaust turbocharger 13 and the resonance chamber 35 are not provided as compared with the case of FIG. Further, in the case of FIG. 14, the volume expansion chamber 60 is provided in the exhaust passage 20 on the upstream side (the engine 1 side) of the exhaust passage of the EGR passage 30 as compared with the case of FIG. I have. By providing the volume expansion chamber 60, the fluctuation of the exhaust pressure in the EGR passage 30 is reduced, the differential pressure between the exhaust pressure and the intake pressure is also reduced (see FIG. 15), and the fluctuation of the EGR gas concentration is reduced. This is preferable in terms of reduction. .

Although the embodiment has been described above, the present invention is not limited to this, and includes, for example, the following case. The engine 1 is not limited to a diesel engine, but may be a spark ignition engine represented by a gasoline engine. The introduction position of the EGR gas into the intake passage 10 can be arbitrarily selected as long as it is an intake passage portion for a plurality of cylinders.

The EGR valve is divided into two branch (independent) EGR
The EGR valves may be provided in both of the passages 31 and 32 so as to control the respective EGR valves individually (the EGR valves are reduced in size, which is advantageous in terms of responsiveness). The purpose of the present invention is not limited to what is explicitly specified, but also implicitly includes providing what is substantially preferred or expressed as an advantage. Further, the present invention can be expressed as a control method.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part showing an EGR gas inlet portion.

FIG. 3 is an enlarged system diagram of an EGR valve portion.

FIG. 4 is a diagram showing a state of fluctuations of an exhaust pressure, an intake pressure, and a differential pressure thereof.

FIG. 5 is a diagram showing a state of fluctuation of an EGR gas concentration.

FIG. 6 is a diagram showing a state in which fluctuations in EGR gas concentration are reduced.

FIG. 7 is a diagram illustrating a relationship between a shift amount of a fluctuation cycle of an EGR gas concentration and a fluctuation amplitude of an EGR gas concentration.

FIG. 8 is a diagram showing a feedback control system for setting a target air-fuel ratio.

FIG. 9 is a characteristic diagram for schematically explaining the control contents of FIG. 8;

FIG. 10 is a characteristic diagram for schematically explaining the control contents of FIG. 8;

FIG. 11 is a characteristic diagram for schematically explaining the control contents of FIG. 8;

FIG. 12 is a characteristic diagram for schematically explaining the control contents of FIG. 8;

FIG. 13 is a view showing another embodiment of the present invention and corresponding to FIG. 2;

FIG. 14 illustrates yet another embodiment of the present invention.
The figure corresponding to FIG.

FIG. 15 is a view showing pressure fluctuations in the embodiment of FIG. 14 and corresponding to FIG. 4;

[Explanation of symbols]

 1: engine 2: combustion chamber 8: fuel injection valve 9: common rail 10: intake passage 12: air flow meter (intake air amount detection means) 15: surge tank 20: exhaust passage 30: EGR passage 31: branch EGR Passage (upstream side) 31a: EGR gas inlet (upstream side) 31A: EGR connection pipe 32: branch EGR passage (downstream side) 32a: EGR gas inlet (downstream side) 32A: EGR connection pipe 33: EGR cooler 34: EGR valve 35: Resonance chamber 55: Control valve 60: Volume expansion chamber P: Pump

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Hayashibara 3-1, Fuchi-machi, Shinchu, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Keiji Araki 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. F term (reference) 3G062 AA01 AA03 AA05 BA02 BA04 BA05 CA04 DA04 EA08 EB15 ED05 ED08 ED11 FA04 FA06 FA11 GA01 GA04 GA06 GA15

Claims (19)

[Claims] A first EGR gas inlet is opened in an intake passage for supplying intake air to a plurality of cylinders, and a second EGR gas is provided downstream of the intake passage in an intake flow direction.
A gas introduction port is opened, and the distance between the first EGR gas introduction port and the second EGR gas introduction direction in the intake passage is determined by the variation of the EGR gas concentration at the first EGR gas introduction port and the second EGR gas introduction port. E
An exhaust gas recirculation device for an engine, characterized in that fluctuations in EGR gas concentration downstream of the second EGR gas inlet are reduced by interference with fluctuations in GR gas concentration. 2. The fuel control system according to claim 1, wherein: fuel control means for controlling an amount of fuel supplied to the engine; intake air amount detection means for detecting an intake air amount; an EGR valve for adjusting an EGR gas amount; The EGR so that the actual air-fuel ratio obtained based on the fuel amount actually supplied to the engine by the means and the actual intake air amount detected by the intake air amount detecting means becomes a predetermined target air-fuel ratio. E to control the valve
An exhaust gas recirculation device for an engine, further comprising: a GR control unit. A fuel control means for controlling an amount of fuel supplied to the engine; an intake air amount detecting means for detecting an intake air amount; an EGR valve for adjusting an EGR gas amount; Controlling the EGR valve so that the actual air-fuel ratio obtained based on the amount of fuel supplied to the intake air and the actual amount of intake air detected by the intake air amount detection means becomes a predetermined target air-fuel ratio.
And GR control means. An exhaust gas recirculation system for an engine, comprising: an intake passage for supplying intake air to a plurality of cylinders;
The first EGR gas inlet is opened, and the second EGR gas inlet is opened on the downstream side of the intake passage in the direction of intake air flow. The center of the first EGR gas inlet and the center of the second EGR gas inlet is opened. When the center-to-center intake passage volume is V, the intake charge amount of one cylinder is α, and n is an integer including 0, the relationship is set so as to satisfy the relational expression of n × α + α / 3 ≦ V ≦ n × α + 2α / 3. An exhaust gas recirculation device for an engine. 4. The engine according to claim 3, wherein a center-to-center distance between the two EGR gas introduction ports is set to be larger than a pipe diameter of the intake passage at the center-to-center distance. Exhaust gas recirculation device. 5. The method according to claim 3, wherein the first EGR gas passage for the first EGR gas inlet including the first EGR gas inlet is smaller than a minimum effective opening area.
An exhaust gas recirculation device for an engine, wherein a minimum effective opening area of a second EGR gas passage for a second EGR gas inlet including the second EGR gas inlet is set smaller. 6. A vehicle according to claim 5, wherein one common EGR passage extending from the exhaust passage is provided with two common EGR passages.
And one branch EGR passage is connected to the first EG.
The first EGR passage is connected to the R gas inlet, and the other branch EGR passage is the second EGR passage connected to the second EGR gas inlet. The EGR valve is provided only in the common EGR passage. An exhaust gas recirculation device for an engine. 7. The air conditioner according to claim 5, wherein the first EGR passage includes: a first EGR gas inlet;
A first EGR gas connection port connected to the first EGR gas introduction port, wherein the second EGR passage includes the second EGR gas introduction port,
A second EGR gas inlet port connected to the second EGR gas inlet port, wherein the effective opening area of the second EGR gas inlet port is set smaller than the effective opening area of the first EGR gas inlet port. An exhaust gas recirculation device for an engine, wherein the first EGR connection pipe and the second EGR connection pipe have the same diameter. 8. The first EGR gas passage for the first EGR gas introduction port including the first EGR gas introduction port, and the second EGR gas for the second EGR gas introduction port including the second EGR gas introduction port. An exhaust gas recirculation device for an engine, wherein a control valve that is closed when the engine is in a predetermined operation state is provided only in the second EGR passage among the passages. 9. The exhaust gas recirculation system according to claim 8, wherein the predetermined operation state in which the control valve is closed is a time when the engine is accelerating. 10. The intake passage according to claim 3, wherein a suction passage is provided downstream of the second EGR gas inlet.
An exhaust gas recirculation device for an engine, comprising a fuel tank. 11. The air intake passage according to claim 3, wherein the two E-shaped portions are formed in a substantially linear portion of the intake passage.
A GR gas inlet is opened, and the two Es are provided at substantially the same position in the circumferential direction of the intake passage.
An exhaust gas recirculation device for an engine, wherein a GR gas inlet is open. 12. A vehicle according to claim 5, wherein one common EGR passage extending from the exhaust passage is provided with two common EGR passages.
And one branch EGR passage is connected to the first EG.
The first EGR passage connected to the R gas introduction port, the other branch EGR passage is the second EGR passage connected to the second EGR passage, and the EGR valve is disposed in the common EGR passage. EGR from the second EGR passage to the 2EGR passage
An exhaust gas recirculation device for an engine, further comprising a control valve for adjusting a gas amount, wherein a fully opened lift amount of the control valve is set smaller than a fully opened lift amount of the EGR valve. 13. An exhaust gas recirculation system for an engine according to claim 12, wherein said control valve is closed prior to said EGR valve when the engine is accelerated. 14. An exhaust gas recirculation system for an engine according to claim 3, wherein a volume expansion chamber is provided in the exhaust passage of the engine upstream of the EGR gas outlet. 15. An exhaust gas recirculation system for an engine according to claim 3, wherein an EGR cooler is provided in an EGR passage upstream of said EGR valve. 16. An exhaust gas recirculation system for an engine according to claim 3, further comprising a turbocharger of an exhaust turbo type, wherein a resonance chamber is connected to an EGR passage upstream of said EGR valve. 17. The method according to claim 1, wherein:
3. The exhaust gas recirculation device for an engine according to claim 1, wherein the engine is a direct-injection diesel engine that injects fuel directly into a cylinder. 18. The fuel injection valve according to claim 17, wherein a common rail to which high-pressure fuel is supplied by a fuel pump is provided, and a fuel injection valve of each cylinder is connected to the common rail. An exhaust gas recirculation device for an engine, wherein an electronic control method in which a timing and a valve opening amount are electronically controlled. 19. An exhaust gas recirculation system for an engine according to claim 1, wherein the amount of EGR gas introduced from each of the EGR gas introduction ports is set to be substantially equal to each other. .