JP2003293731A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for easily and precisely controlling the amount of exhaust gas flowing into a particulate filter to be a target amount. <P>SOLUTION: The exhaust emission control device has an upstream side exhaust passage 25a communicating with a combustion chamber in the internal combustion engine. The upstream side exhaust passage is parted at a branch portion 25b into at least two branch exhaust passages. The particulate filter 26 is arranged in one of the branch exhaust passages and a flow control valve 28 is arranged at the branch portion. With the adjustment of the operating position of the flow control valve, the amount of the exhaust gas flowing into the branch exhaust passage can be controlled. The exhaust emission control valve comprises parameter measuring means 49, 50. The amount of the exhaust gas flowing into at least one branch exhaust passage is calculated in accordance with parameters measured by the parameter measuring means and the operating position of the flow control valve is adjusted so that the calculated amount of the exhaust gas becomes the target amount. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device for an internal combustion engine.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 2001-27144 discloses an exhaust gas purifying device capable of reversing the direction of exhaust gas flowing into a particulate filter (hereinafter referred to as a filter). In such an exhaust emission control device, the engine exhaust passage is branched at the branch portion into the first exhaust passage in which the filter is arranged and the second exhaust passage communicating with the atmosphere, and the tip end of the first exhaust passage is returned to the branch portion. Connected. A switching valve that can be switched stepwise is arranged in the branch portion, and the amount of exhaust gas flowing into the filter is controlled according to the position of the switching valve.

In the exhaust gas purifying apparatus disclosed in the above publication, when the filter should be bypassed, that is, when the target amount of exhaust gas flowing into the filter is substantially zero, the switching valve is held at a predetermined neutral operating position. It When the switching valve is in the neutral operating position, it is held parallel to the flow direction of the exhaust gas flowing into the branch portion from the upstream. In this case, a large pressure difference does not occur in the exhaust gas passing through both sides of the switching valve, so most of the exhaust gas that has flowed into the branch portion flows out to the second exhaust passage along the switching valve. Therefore, when the switching valve is in the neutral operating position, almost no exhaust gas flows into the first exhaust passage even though the flow path to the first exhaust passage in which the filter is arranged is not closed, and therefore the filter is The amount of exhaust gas flowing into is controlled to almost zero which is the target amount.

[0004]

However, since the shapes of the branch portion and the exhaust passage and the switching valve vary, the neutral operating position of the switching valve also varies from exhaust purification device to exhaust emission control device. Therefore, even if the switching valve is positioned at the uniformly set neutral operating position, the amount of exhaust gas flowing into the filter may not reach the target amount, that is, substantially zero.

Therefore, an object of the present invention is to provide an exhaust gas purification device which can easily and precisely control the amount of exhaust gas flowing into a particulate filter to a target amount.

[0006]

In order to solve the above problems, in the first invention, an upstream side exhaust passage communicating with the combustion chamber of the internal combustion engine is provided, and the upstream side exhaust passage has at least two branch portions. It branches into a branch exhaust passage, a particulate filter is arranged in at least one of these branch exhaust passages, and a flow rate adjusting valve whose operating position can be continuously adjusted is arranged in the branching section. An exhaust emission control device capable of adjusting the amount of exhaust gas flowing into at least one branch exhaust passage by adjusting a position, comprising parameter measurement means for measuring a parameter relating to exhaust gas, The amount of exhaust gas flowing into the at least one branch exhaust passage is calculated based on the parameter measured by the parameter measuring means. And, the amount of exhaust gas that is calculated has to adjust the working position of the flow control valve so that the target amount of exhaust gas. According to the first aspect of the present invention, the amount of exhaust gas flowing into at least one branch exhaust passage is calculated based on the parameter measured by the parameter measuring means, so that the actual amount of exhaust gas flowing into the branch exhaust passage is accurately calculated. It is calculated. Furthermore, since the flow rate adjustment valve changes continuously, even if the accurately calculated exhaust gas amount is slightly different from the target exhaust gas amount, it is possible to correct the slight difference in exhaust gas amount precisely. The flow control valve can be adjusted. By slightly adjusting the flow rate adjusting valve according to the slight difference in the exhaust gas amount, the actual exhaust gas amount becomes almost the same as the target exhaust gas amount. Therefore, the exhaust gas amount flowing into the at least one branch exhaust passage. Can always be precisely adjusted to the target exhaust gas amount.

According to a second aspect of the present invention, in the first aspect of the present invention, the tip end portion of the at least one branch exhaust passage is connected to the branch portion by returning to the branch portion. At least a part of the exhaust gas flowing into the portion may flow through the at least one branch exhaust passage in one direction or the opposite direction, and then may flow out to the remaining branch exhaust passage through the branch portion. it can. In this case, the exhaust gas can theoretically flow into three ports such as openings at both ends of at least one branch exhaust passage and openings of the remaining branch exhaust passages. In such a configuration, the flow of the exhaust gas in the branch portion is complicated, and thus it is a very complicated work to previously determine the operating position of the flow rate adjusting valve corresponding to each target amount, as in the conventional case. However, in the second invention, the amount of exhaust gas flowing into each port can be set as the target amount without previously obtaining the operating position of the flow rate adjusting valve.

According to a third invention, in the second invention, the target exhaust gas amount is substantially zero. In the third aspect of the invention, the exhaust gas flowing from the upstream side exhaust passage into the branch portion flows only into the remaining branch exhaust passage. Therefore, since at least one branch exhaust passage, and the exhaust gas does not flow to the particulate filter arranged in this branch exhaust passage,
The particulate filter can be completely bypassed when the exhaust gas should not flow into the particulate filter, such as when the temperature of the particulate filter has risen above the allowable temperature.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the flow rate adjusting valve is arranged in a flow direction of the exhaust gas flowing from the upstream side exhaust passage to the branch portion when the operating position of the flow rate adjusting valve changes. It is a valve in which the angle of the flow rate adjusting valve changes, and the branch part has a port leading to the upstream side exhaust passage,
The angle of the flow rate adjusting valve is larger than the angle when the flow rate adjusting valve comes into contact with the inner peripheral wall of the port. Generally, when the flow rate adjusting valve is held at a position where all the exhaust gas flowing from the upstream side exhaust passage into the branch portion flows into the at least one branch exhaust passage, the exhaust gas receives exhaust resistance due to the particulate filter. On the other hand, when the flow rate adjusting valve is held at a position where the exhaust gas does not flow into the branch exhaust passage, the exhaust gas does not receive the exhaust resistance due to the particulate filter. In such a case, the exhaust resistance received by the exhaust gas is reduced depending on the operating position of the flow rate control valve, so that the back pressure of the internal combustion engine is reduced and the operating state of the internal combustion engine is seriously affected. According to the fourth aspect of the invention, the flow rate adjusting valve is always angled with respect to the flow direction of the exhaust gas flowing into the branch portion. Therefore,
Exhaust gas receives exhaust resistance from the flow rate adjusting valve even when it does not receive exhaust resistance due to the particulate filter, and as a result, it is possible to prevent the back pressure of the internal combustion engine from dropping significantly when the operating position of the flow rate adjusting valve is changed. .

According to a fifth aspect of the present invention, in the third or fourth aspect of the invention, the flow rate adjusting valve is arranged in the direction of flow of the exhaust gas flowing from the upstream side exhaust passage to the branch portion when the operating position of the flow rate adjusting valve changes. This is a valve in which the angle of the flow control valve changes, and when the flow control valve is perpendicular to the flow direction of the exhaust gas, the amount of exhaust gas flowing into the at least one branch exhaust passage becomes close to zero, and the target exhaust gas When the amount is almost zero, the flow rate adjusting valve is made substantially vertical to the flow direction of the exhaust gas. As described above, when the target exhaust gas amount is almost zero, the exhaust gas bypasses the particulate filter, so the exhaust resistance of the particulate filter becomes almost zero. On the other hand, when the flow rate adjusting valve is perpendicular to the flow direction of the exhaust gas, the exhaust resistance by the flow rate adjusting valve becomes the largest. In the fifth aspect of the invention, the exhaust resistance of the flow rate adjusting valve is maximized when the exhaust resistance of the particulate filter becomes substantially zero. Therefore, the exhaust resistance of the exhaust gas does not fluctuate significantly as a whole. The fluctuation of the back pressure received by the internal combustion engine is also eliminated, and the internal combustion engine can be operated stably.

According to a sixth aspect of the present invention, in any one of the second to fifth aspects, the branch portion is an upstream exhaust passage,
One end of the at least one branch exhaust passage, the other end of the at least one branch exhaust passage, and the first port, the second port, the third port, and the fourth port leading to the second branch exhaust passage When the flow rate adjusting valve is held at a position such that all the exhaust gas flowing from the upstream side exhaust passage into the branch portion flows into the at least one branch exhaust passage, the flow rate adjusting valve has an inner peripheral wall of the second port. And the inner peripheral wall of the third port. When the flow rate adjusting valve is held at a position such that all the exhaust gas flowing from the upstream side exhaust passage into the branch portion flows into the at least one branch exhaust passage, the flow rate adjusting valve causes the inner peripheral wall of the first port and the fourth port. When it is in contact with the inner peripheral wall of the second port, a groove is formed between the flow rate adjusting valve and the inner peripheral wall of the fourth port. Exhaust gas becomes turbulent due to this groove, and the pressure loss of exhaust gas has increased. On the other hand, in the sixth aspect of the invention, the flow control valve comes into contact with the inner peripheral wall of the second port and the inner peripheral wall of the third port to form a groove oriented in a direction different from that described above. However, since the direction of the groove is different, unlike the case described above, the exhaust gas does not become a turbulent flow due to the groove, and therefore the pressure loss of the exhaust gas does not increase.

[0012] In the seventh invention, in the third invention, the upstream exhaust passage is disposed stored SO _x material, SO _x in the exhaust gas when the air-fuel ratio of the stored SO _x material exhaust gas is lean When the air-fuel ratio of the exhaust gas is rich and the temperature of the SO _x holding material exceeds a predetermined temperature, the held SO _x can be released, and when the SO _x is released, the target exhaust gas amount is almost It is zero. When stored SO _x material from SO _x is brought into disengagement, SO _x are contained in the exhaust gas flowing into the bifurcation. At this time, the target exhaust gas amount is set to zero, so that the exhaust gas amount that flows into the particulate filter becomes substantially zero, so that SO _x is prevented from flowing into the particulate filter, and thus the SOx flows into the particulate filter. It is prevented that _x is retained.

In an eighth aspect based on any one of the second to seventh aspects, the parameter measuring means is two pressure sensors, and these pressure sensors are provided on both sides of the particulate filter in the at least one branch exhaust passage. One for each. When the pressure sensor is arranged in this way, it can be used not only as a parameter measuring means but also as a pressure loss detecting means for measuring the pressure loss due to the particulate filter.

In a ninth aspect based on any one of the second to seventh aspects, the parameter measuring means is two temperature sensors, and these temperature sensors are provided on both sides of the particulate filter in the at least one branch exhaust passage. One for each. When the temperature sensor is arranged in this way, it can be used not only as a parameter measuring means but also for calculating the temperature of the particulate filter.

In a tenth aspect of the present invention according to any one of the second to seventh aspects, the parameter measuring means is a flow rate sensor, a NO _x sensor, an HC sensor, an A / F sensor and O _2.
Any one of the sensors, the sensor being located in the branch exhaust passage.

According to an eleventh invention, in the first invention,
The branch exhaust passage includes a first branch exhaust passage in which a particulate filter is arranged, and a second branch exhaust passage, and the tip of the second branch exhaust passage merges with the first branch exhaust passage at a junction downstream of the branch. The upstream exhaust passage upstream of the branch portion, the first branch exhaust passage between the branch portion and the joining portion, the second branch exhaust passage between the branch portion and the joining portion, and the branch exhaust downstream of the joining portion. The parameter measuring means is arranged in at least two of the passages. The parameter measuring means is a means for measuring the parameter for the purpose of controlling the amount of exhaust gas flowing into the particulate filter. However, depending on the place where the parameter measuring means is arranged, the parameter measured by the parameter measuring means is described above. It can also be used for purposes other than the purpose. In the eleventh aspect, the degree of freedom in selecting the position where the parameter measuring unit is arranged is high. Therefore, the parameter measuring unit can be effectively used by appropriately selecting the position where the parameter measuring unit is arranged.

In a twelfth aspect based on the eleventh aspect, the parameter measuring means measures the parameters of the exhaust gas other than the flow rate of the exhaust gas.

[0018]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a compression ignition type internal combustion engine equipped with an exhaust purification system of the present invention. The exhaust emission control device used in the present invention can also be installed in a spark ignition type internal combustion engine.

1 and 2, 1 is an engine body, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an electrically controlled fuel injection valve, and 7
Is an intake valve, 8 is an intake port, 9 is an exhaust valve, and 10 is an exhaust port. The intake port 8 is connected to a surge tank 12 via a corresponding intake branch pipe 11, and the surge tank 12 is connected to a compressor 15 of an exhaust turbocharger 14 via an intake duct 13.

A step motor 16 is installed in the intake duct 13.
A throttle valve 17 driven by the above is arranged, and a cooling device 18 for cooling intake air flowing in the intake duct 13 is arranged around the intake duct 13. Figure 1
In the internal combustion engine shown in (1), the engine cooling water is introduced into the cooling device 18, and the intake air is cooled by the engine cooling water. On the other hand, the exhaust port 10 is connected to the exhaust turbine 21 of the exhaust turbocharger 14 via the exhaust manifold 19 and the exhaust pipe 20, and the outlet of the exhaust turbine 21 is connected to the exhaust pipe 20.
Casing 23 containing SO _x holding material 22 via a
Is connected to the entrance of. The outlet of the casing 23 is the exhaust pipe 2
It is connected to the inlet of the reversal type exhaust emission control device 25 via 4. As shown in FIG. 2, the inversion type exhaust purification device 25 includes an upstream side exhaust pipe (upstream side exhaust passage) 25a and a branch portion 25b.
A casing 25e (hereinafter, referred to as a filter) that holds a first branch exhaust pipe (first branch exhaust passage) 25c, a second branch exhaust pipe (second branch exhaust passage) 25d, and a particulate filter (hereinafter referred to as a filter) 26. , Called the holding casing)
And a downstream side exhaust pipe (downstream side branch exhaust passage) 25f and a filter 26.

The exhaust manifold 19 and the surge tank 12 are connected to each other via an exhaust gas recirculation (hereinafter referred to as EGR) passage 29, and an electric control type EGR control valve 30 is arranged in the EGR passage 29. A cooling device 31 for cooling the EGR gas flowing in the EGR passage 30 is arranged around the EGR passage 29. In the internal combustion engine shown in FIG. 1, the engine cooling water is guided into the cooling device 31, and the engine cooling water cools the EGR gas.

On the other hand, each fuel injection valve 6 is connected to a fuel reservoir, a so-called common rail 32, via a fuel supply pipe 6a. Fuel is supplied into the common rail 32 from an electrically controlled variable discharge fuel pump 33, and the fuel supplied into the common rail 33 is supplied to the fuel injection valve 6 through each fuel supply pipe 6a. A fuel pressure sensor 34 for detecting the fuel pressure in the common rail 32 is attached to the common rail 32, and the fuel pump 33 is arranged so that the fuel pressure in the common rail 32 becomes the target fuel pressure based on the output signal of the fuel pressure sensor 34. Is controlled.

The electronic control unit 40 is composed of a digital computer, and has a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, a CPU (Microprocessor) 44, an input port 45 and an input port 45 which are connected to each other by a bidirectional bus 41. The output port 46 is provided. The output signal of the fuel pressure sensor 34 is input to the input port 45 via the corresponding AD converter 47. A first pressure sensor 49 is arranged in the first branch exhaust pipe 25c near the branch portion 25b, and the pressure sensor 49 measures the pressure in the first branch exhaust pipe 25c. On the other hand, the second pressure sensor 50 is arranged in the second branch exhaust pipe 25d near the branch portion 25b, and the pressure sensor 50 measures the pressure in the second branch exhaust pipe 25d. The output signals of these pressure sensors 49 and 50 are input to the input port 45 via the corresponding AD converters 47.

The accelerator pedal 51 includes an accelerator pedal 5
Load sensor 5 that generates an output voltage proportional to the stepping amount of 1
2 is connected, and the output voltage of the load sensor 52 corresponds to A
It is input to the input port 45 via the D converter 47. Further, the input port 45 has a crankshaft of, for example, 30
A crank angle sensor 53 that generates an output pulse each time it rotates is connected. On the other hand, the output port 46 is connected via the corresponding drive circuit 48 to the fuel injection valve 6, the throttle valve driving step motor 16, and the flow rate adjusting valve step motor 2.
7, EGR control valve 30, and fuel pump 33.

Next, an exhaust purification system of a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the exhaust gas purification apparatus of the first embodiment uses the SO _x holding material 2
2 and a reversal type exhaust gas purification device 25, but first, referring to FIG.
The inversion type exhaust emission control device 25 will be described with reference to FIG.
FIG. 2A is a diagram showing the reversal type exhaust purification device 25 when the flow rate adjusting valve 28 is in the first operating position, and FIG.
FIG. 2 is a diagram showing the reversal type exhaust gas purification device 25 when the flow rate adjusting valve 28 is in the second operation position, and FIG. 2C is the reversal type exhaust gas purification device 25 when the flow rate adjusting valve 28 is in the neutral operation position. FIG.

One end of the upstream side exhaust pipe 25a is connected via the exhaust pipe 24 to the SO _x holding material 22 arranged upstream of the reversal type exhaust purification device 25. Upstream exhaust pipe 25a
The other end of the first branch exhaust pipe 2 at the branch portion 25b.
5c, the second branch exhaust pipe 25d, and the downstream exhaust pipe 25f are branched into three exhaust pipes. The upstream side exhaust pipe 25a and the downstream side exhaust pipe 25f are located on a substantially straight line. Further, the first branch exhaust pipe 25c and the second branch exhaust pipe 25d branch in opposite directions to each other and substantially vertically to the upstream side exhaust pipe 25a and the downstream side exhaust pipe 25f. Therefore,
An upstream exhaust pipe 25a and a downstream exhaust pipe 25f, and a first branched exhaust pipe 25c and a second branched exhaust pipe 25d are connected to the branch portion 25b in a cross shape.

The end of the first branch exhaust pipe 25c opposite to the end connected to the branch portion 25b and the second branch exhaust pipe 2
A holding casing 25e is connected between the end connected to the branch portion 25b of 5d and the end opposite to the end. The first branch exhaust pipe 25c and the second branch exhaust pipe 25d are formed symmetrically with respect to the axes of the upstream exhaust pipe 25a and the downstream exhaust pipe 25f. Therefore, the first branch exhaust pipe 25
The distance between the ends of c is equal to the distance between the ends of the second branch exhaust pipe 25d.

A flow rate adjusting valve 28 is provided at the branch portion 25b. The flow rate adjusting valve 28 continuously rotates around the center of the branch portion 25, and the angle changes with respect to the axes of the upstream exhaust pipe 25a and the downstream exhaust pipe 25f. In this embodiment, since the flow direction of the exhaust gas flowing from the upstream exhaust pipe 25a into the branch portion 25b is the same as the axial direction of the upstream exhaust pipe 25a, the exhaust gas flows into the branch portion 25b from the upstream exhaust pipe 25a. Flow rate adjusting valve 28 for the flow direction of exhaust gas
It can be said that the angle θ (see FIG. 3; hereinafter, simply referred to as the angle of the flow rate adjusting valve 28) changes.

The flow rate adjusting valve 28 of the present embodiment is roughly divided and rotates between three operating positions having different angles. These three positions are the first operating position shown in FIG.
The second operating position shown in (B) and the neutral operating position shown in FIG. 2 (C). Branch portion 2 from the upstream exhaust pipe 25a
Of the exhaust gas that flows into 5b (hereinafter referred to as the branch portion inflow exhaust gas), the amount of exhaust gas that should flow into the first branch exhaust pipe 25c or the second branch exhaust pipe 25d is referred to as the target branch exhaust gas amount. The target branch exhaust gas amount differs at the three operating positions. In the first operating position, the first branch exhaust pipe 25
The target branch exhaust gas amount to c is equal to the branch portion inflow exhaust gas amount, the target branch exhaust gas amount to the second branch exhaust pipe 25d is equal to the branch portion inflow exhaust gas amount in the second operating position, and is in the neutral operating position. The target branch exhaust gas amount to the first branch exhaust pipe 25c and the second branch exhaust pipe 25d is near zero.

When the flow rate adjusting valve 28 is in the first operating position shown in FIG. 2 (A), it is easy to set the exhaust gas amount actually flowing into the branch exhaust pipe 25c as the target exhaust gas amount. The reason is that in the first operating position, the exhaust pipe into which the exhaust gas flowing into the branch portion should flow (that is, the first branch exhaust pipe 25).
Exhaust pipes other than c) are physically cut off from the upstream exhaust pipe 25a. Therefore, in the first operating position, all the inflowing exhaust gas flows into the first branch exhaust pipe 25c, and the exhaust gas flowing into the first branch exhaust pipe 25c passes through the filter 26 held by the holding casing 25e in one direction. Flow into the second branch exhaust pipe 25d, and then again into the branch section 2
Return to 5b. All the exhaust gas returned from the second branch exhaust pipe 25d to the branch portion 25b flows into the downstream side exhaust pipe 25f.
Note that in the following, the exhaust gas is exhausted from each branch exhaust pipe 25c, 25d.
The flow direction of the filter 26 will be described as a forward direction.

When the flow rate adjusting valve 28 is in the second operating position shown in FIG. 2B, the exhaust gas actually flowing into the second branch exhaust pipe 25d for the same reason as in the first operating position. It is easy to set the amount as the target exhaust gas amount.
Therefore, in the second operating position, all the exhaust gas flowing into the branch portion flows into the second branch exhaust pipe 25d, and the second branch exhaust pipe 25
The exhaust gas that has flowed into d passes through the filter 26 held by the holding casing 25e in the direction opposite to the one direction when the flow rate adjusting valve 28 is in the first operating position, and enters the first branch exhaust pipe 25c. The flow then returns to the branching portion 25b again. All the exhaust gas returned from the first branch exhaust pipe 25c to the branch portion 25b flows into the downstream side exhaust pipe 25f. In the following description, the direction in which the exhaust gas flows in each of the branch exhaust pipes 25c and 25d and the filter 26 will be described as the reverse direction.

On the other hand, when the flow rate adjusting valve 28 is in the neutral operating position shown in FIG. 2C, each branch exhaust pipe 25 is actually
It is difficult to make the amount of exhaust gas flowing into c and 25d close to zero. The reason is that, as shown in FIG. 2C, the exhaust pipes other than the exhaust pipe (that is, the downstream side exhaust pipe 25f) into which the branch portion inflowing exhaust gas should flow are not physically blocked at the neutral operating position. Therefore, the exhaust gas that has flowed into the branch portion is exhausted from the branch exhaust pipes 25c and 25d and the downstream exhaust pipe 25.
It can be said that they are physically connected to both of f. That is, since the amount of exhaust gas flowing into each of the branch exhaust pipes 25c and 25d and the downstream side exhaust pipe 25f is determined only by the angle θ of the flow rate adjusting valve 28, the actual amount of branch exhaust gas is equal to the target branch exhaust gas amount (that is, If the angle θ of the flow rate adjusting valve 28 deviates slightly from the angle at which it becomes (near zero), the branch exhaust gas amount will not be the target branch exhaust gas amount.

Here, conventionally, the neutral operating position is predetermined. In other words, at the time of manufacturing the exhaust purification device, that is, in the initial state, the flow rate adjustment valve 2 at the neutral operating position
The angle θ of 8 was set to such an angle that the branch exhaust gas amount becomes the target branch exhaust gas amount (hereinafter referred to as the target angle).

However, when the neutral operating position of the flow rate adjusting valve is set in advance, the flow rate adjusting valve is set in a predetermined neutral operating position due to variations in the exhaust pipe and the flow rate adjusting valve for each exhaust gas purification device as described above. Even if it is positioned at, the branch exhaust gas amount may not reach the target branch exhaust gas amount.

By the way, in the present embodiment, pressure sensors 49 and 50 are arranged as parameter measuring means, and these pressure sensors 49 and 50 branch the pressure in the first branch exhaust pipe 25c near the branch portion 25b as a parameter of the exhaust gas. The pressure in the second branch exhaust pipe 25d near the portion 25b is measured. If there is no difference between the measured pressure in the first branch exhaust pipe 25c and the measured pressure in the second branch exhaust pipe 25d,
There is almost no flow of exhaust gas in the branch exhaust pipes 25c and 25d and in the filter 26, so that the branch exhaust gas amount is also the target branch exhaust gas amount (near zero in this embodiment). Therefore, in this embodiment, the target angle of the flow rate adjusting valve 28 is the pressure P ₁ in the first branch exhaust pipe 25c measured by the first pressure sensor 49 and the second branch exhaust pipe 25d measured by the second pressure sensor 50. The internal pressure P ₂ is substantially the same as the internal pressure P _2, and the flow rate adjusting valve 28 is adjusted to such a target angle as the neutral operating position control.

The neutral operating position control will be described with reference to FIG. FIG. 3 is an enlarged view of the branch portion 25b in the state of FIG. For example, the first branch exhaust pipe 25
When the pressure P _{1 in} c is higher than the pressure P ₂ in the second branch exhaust pipe 25d, since the exhaust gas flows from the higher pressure side to the lower pressure side, at least a part of the branch portion inflow exhaust gas Flows in the forward direction so as to flow into the first branch exhaust pipe 25c and return from the second branch exhaust pipe 25d to the branch portion 25b. When the exhaust gas is flowing in this way, the flow rate adjusting valve 28 is slightly rotated in the first direction 55 shown in FIG. By doing so, the passage to the first branch exhaust pipe 25c defined by the inner peripheral wall of the branch portion 25b and the flow rate adjusting valve 28 becomes narrower, so the amount of branch exhaust gas flowing into the first branch exhaust pipe 25c decreases. Therefore, the amount of exhaust gas flowing in the forward direction decreases, and the pressure P ₁ and the pressure P ₂ approach each other.

On the other hand, the pressure P ₂ in the second branch exhaust pipe 25d
Is higher than the pressure P ₁ in the first branch exhaust pipe 25c,
At least a part of the exhaust gas flowing into the branch portion flows in the opposite direction to the above, contrary to the case described above. In this case, the flow rate adjusting valve 28 is slightly rotated in the second direction 56 shown in FIG. By doing so, the passage to the second branch exhaust pipe 25d defined by the inner peripheral wall of the branch portion 25b and the flow rate adjusting valve 28 becomes narrower, so the amount of branch exhaust gas flowing into the second branch exhaust pipe 25d decreases. Therefore, the amount of exhaust gas flowing in the opposite direction decreases, and the pressures P ₁ and P ₂ approach each other. By continuing the adjustment of the flow rate adjusting valve 28 by repeating the above-described operation, the angle of the flow rate adjusting valve 28 always becomes the target angle, and the branch exhaust gas amount becomes the target exhaust gas amount.

As described above, in the present invention, the flow rate adjusting valve 28
Is continuously adjusted so that the branch exhaust gas amount always becomes the target branch exhaust gas amount based on the parameter measured by the parameter measuring means for measuring the exhaust gas parameter.

Although it has been described that the flow rate adjusting valve 28 is slightly rotated, the rotation angle for rotating the flow rate adjusting valve 28 is the pressure in the first branch exhaust pipe 25c measured by the pressure sensors 49 and 50. It may be determined according to the relative pressure difference ΔP between P ₁ and the pressure P ₂ in the second branch exhaust pipe 25d. This relative pressure difference ΔP changes according to the flow rate of the exhaust gas flowing through the branch exhaust pipes 25c and 25d and the filter 26. If the flow rate of the exhaust gas flowing through these is large, the relative pressure difference ΔP.
Is large, and the relative pressure difference ΔP is small if the flow rate of the exhaust gas is small. Therefore, when the relative pressure difference ΔP is large, the rotation angle is increased, and when the relative pressure difference ΔP is small, the rotation angle is decreased, so that the actual branch exhaust gas amount is quickly adjusted to the target branch exhaust gas amount. Then, the flow rate adjusting valve 28 is adjusted.

Further, in this embodiment, the pressure sensors 49, 5
0 is arranged in the first branch exhaust pipe 25c and the second branch exhaust pipe 25d, respectively, but these pressure sensors may be arranged in the upstream side exhaust pipe 25a and the downstream side exhaust pipe 25f, respectively. In this case, when the neutral operating position control is performed and the target branch exhaust gas amount is near zero, the actual branch exhaust gas amount becomes the target branch exhaust gas amount when the pressure measured by each pressure sensor is almost equal. It is determined that

Further, in the above-mentioned embodiment, only the case where the target branch exhaust gas amount is near zero is explained, but other values may be used. In this case, a relative pressure difference with respect to each branch exhaust gas amount is obtained in advance and R is used as a map.
Save in OM42. During operation, the relative pressure difference with respect to the target branch exhaust gas amount is calculated from the map, and the relative pressure difference ΔP between the first pressure sensor 49 and the second pressure sensor 50.
So as to be the relative pressure difference calculated above.
Is adjusted.

Next, the neutral operating position control routine for adjusting the flow rate adjusting valve 28 to the neutral operating position will be described with reference to FIG. When the neutral operating position control is started, first, at step 101, the angle θ of the flow rate adjusting valve 28 is set to 90 °. Next, at step 102, it is judged if P ₁ ≈P ₂ or not, and if P ₁ ≈P ₂ , then the routine proceeds to step 106.

If P ₁ ≈P ₂ is not satisfied in step 102, the process proceeds to step 103. In step 103, P ₁
It is determined whether or not> P ₂ . If P ₁ > P ₂ , then go to step 104. At step 104, the flow rate adjusting valve 28 is slightly rotated in the first direction 55, and the routine proceeds to step 106. On the other hand, in step 103, P ₁
If it is determined to be <P ₂ , the process proceeds to step 105.
At step 105, the flow rate adjusting valve 28 is slightly rotated in the second direction 56, and the routine proceeds to step 106. At step 106, it is judged if the condition for ending the neutral operating position control is satisfied. Here, the termination condition is, for example, that it is determined that the SO _x emission control, which will be described later, should be terminated, or that it is not necessary to lower the temperature of the filter. If the ending condition is not satisfied, the process returns to step 102. On the other hand, if the ending condition is satisfied, the neutral operating position control routine is completed.

By the way, in the first embodiment of the present invention, as shown in FIG.
_{The x-} holding material 22 is arranged. When the ratio of the air supplied to the intake passage and the combustion chamber 5 to the fuel is referred to as the air-fuel ratio of the exhaust gas, the SO _x holding material 22 is used when the air-fuel ratio of the exhaust gas is lean and the air-fuel ratio of the exhaust gas. there temperature of the SO _x held member 22 be substantially stoichiometric or rich when the predetermined temperature or less, to retain the SO _x contained in the exhaust gas flowing into the stored SO _x member 22. In the present embodiment, a compression ignition type internal combustion engine is used, but since this internal combustion engine normally burns in the presence of excess air, it is often operated in a state where the air-fuel ratio of the exhaust gas is lean. The SO _x in the gas is held by the SO _x holding material 22 before flowing into the inversion type exhaust purification device 25. Note that the predetermined temperature of the SO _x holding material 22 at a temperature which is uniquely determined from the material constituting the stored SO _x member 22, stored SO _x when the air-fuel ratio of the exhaust gas is substantially stoichiometric or rich This is the temperature at which SO _x begins to separate from the material.

In addition, SO_xSO held by holding material 22_x
Amount is SO_xExceeding the allowable amount of the holding material, exhaust gas
The air-fuel ratio of SO is almost stoichiometric or rich and SO
_xThe temperature of the holding material 22 is controlled to be equal to or higher than the above predetermined temperature.
(Hereafter, such control is _xThis is called playback control). S
O_xWhen reproduction control is performed, the SO_xHold on holding material 22
SO_xIs released in the exhaust gas. Leave
SO_xIs SO_xDownstream of the holding material 22, a reverse exhaust purification device
Head to Oki 25.

Meanwhile, with a stored SO _x activity and SO _x detachment operates similarly to the filter 26 also stored SO _x member 22 disposed in the inverting type exhaust emission control device 25. Therefore, when the flow rate adjusting valve 28 is in the first operating position or the second operating position so that the exhaust gas flowing into the reversal type exhaust purification device 25 passes through the filter 26, the SO _x holding material 22 is separated from the SO _x holding material 22. SO _x is held by the filter 26. Here, also in the filter 26, the temperature of the filter 26 must be raised to a temperature similar to the above-mentioned predetermined temperature in order to remove the retained SO _x . However, the filter 26 is located remote from the exhaust manifold 19 of the internal combustion engine. Therefore, the temperature of the exhaust gas, which is high in temperature when exhausted from the exhaust manifold 19 of the internal combustion engine, also decreases when it reaches the filter 26 of the reversal type exhaust purification device 25. Therefore, the exhaust gas is used to filter the filter 26.
Is difficult to raise to a temperature similar to the above predetermined temperature. Therefore, even if SO _x is held, it is difficult to remove it, and a large amount of SO _x is held in the filter 26. When a large amount of SO _x is retained in the filter 26 in this way, the filter 26 cannot perform its original function.

[0047] In contrast, in the present embodiment, so as not to SO _x flowing into the stored SO _x member 22 inverted type exhaust emission control device 25 is allowed to disengaged from the flows into the filter 26, the SO _x regeneration control When executing the flow rate adjusting valve 28
Is rotated to the neutral operating position. As described above, in this embodiment, since the exhaust gas does not flow into the filter 26 when the flow rate adjusting valve 28 is in the neutral operating position, S
The SO _x separated from the O _x holding material 22 is the filter 2
Therefore, the filter 26 is not retained by the filter 26,
The original function of is not lost.

As described above, in the present embodiment, when the SO _x regeneration control of the SO _x holding material 22 is executed, the flow rate adjusting valve 22 is rotated to the neutral operating position, which causes the filter 26 to emit SO _x. Are prevented from being retained.
In the present embodiment SO _x flow rate regulating valve 28 so as not to completely flow into the filter 26 starts the SO _x regeneration control since been confirmed that in a neutral operating position.

Next, referring to control SO _x in the SO _x regeneration control of the SO _x held member 22 is prevented from flowing into the filter 26 to FIG. 5 (hereinafter, referred to as SO _x emissions control) SO _x emissions in The control routine will be described. Or when SO _x emissions control amount of the SO _x held in the stored SO _x member 22 exceeds the allowable amount of the SO _x holding material, S from stored SO _x member 22
It is started when O _x should be released, that is, when SO _x emission control is required. When the SO _x discharge control is started, first, at step 121, the neutral operating position control described with reference to FIG. 4 is started. Then step 1
At 22, it is determined whether or not P ₁ ≈P ₂ . P ₁
If not ≈P ₂ , step 122 is repeated.
If P ₁ ≈P ₂ , then go to step 123. In step 123, SO _x regeneration control is started. Next, at step 124, it is judged if the SO _x regeneration control termination condition is satisfied. Here, the SO _x regeneration control termination condition is, for example, that almost all of the SO _x held in the SO _x holding material has been discharged. When it is determined in step 124 that the SO _x regeneration control termination condition is not satisfied, step 124 is repeated. When it is determined in step 124 that the SO _x regeneration control end condition is satisfied, the routine proceeds to step 125, where the SO _x regeneration control is ended. Next, at step 126, the neutral operating position control is ended, and the SO _x emission control routine is ended.

The advantages of the present invention will be described with reference to FIGS. 6 (A) and 6 (B) show the flow rate adjusting valve 28 of the present invention in different operating positions, and FIG.
(A) and (B) show the conventional flow control valve 61 in a different operating position. The arrows in these figures indicate the flow of exhaust gas.

As shown in FIGS. 6A and 6B,
In this embodiment, the angle θ of the flow rate adjusting valve 28 is determined by the flow rate adjusting valve 2
8 is always larger than the angle when it contacts the inner peripheral wall of the port 57a of the upstream side exhaust pipe 25a, and is always smaller than the angle when the flow rate adjusting valve 28 contacts the inner peripheral wall of the port 57f of the downstream side exhaust pipe 25f. . The flow rate adjusting valve 28 rotates within this angle range. That is, both ends of the flow rate adjusting valve 28 are always located in the port 57c of the first branch exhaust pipe 25c and the port 57d of the second branch exhaust pipe 25d. In particular, since the exhaust pipes are connected to the branching portion 25b in a substantially cross shape, the angle θ of the flow rate adjusting valve 28 is close to zero as the neutral operating position of the flow rate adjusting valve 28 that makes the branch exhaust gas amount near zero. It is possible to employ both the position of about 90 ° and the position of about 90 °, but in the present embodiment, the position of about 90 ° is the neutral operating position.

On the other hand, conventionally, as shown in FIGS. 7A and 7B, the angle of the flow rate adjusting valve 61 is set to
Is always smaller than the angle at which the upstream end of the contacting portion with the inner peripheral wall of the port 62c of the first branch exhaust pipe 60c and the inner peripheral wall of the port 62d of the second branch exhaust pipe 25d, and the flow rate adjusting valve 61 is in this angle range. It was turning inside. That is, both ends of the flow rate adjusting valve 61 are always connected to the port 6 of the upstream exhaust pipe 60a.
2a and the port 62f of the downstream exhaust pipe 60f. In particular, the case where the angle of the flow rate adjusting valve 61 is near zero is the neutral operating position.

By the way, conventionally, when the flow rate adjusting valve 61 is in the first operating position and the second operating position and the exhaust gas passes through the filter, the exhaust gas receives exhaust resistance by the filter. However, when the flow rate adjusting valve 61 is in the neutral operating position, the exhaust gas does not pass through the filter and therefore does not experience the exhaust resistance. Further, since the flow rate adjusting valve 61 is substantially parallel to the flow direction of the exhaust gas, the exhaust gas hardly receives exhaust resistance even when passing through the branch portion. Therefore, when the operating position of the flow rate adjusting valve 61 changes, the exhaust resistance suddenly changes greatly. That is, when the flow rate adjusting valve 61 is rotated from the first operation position or the second operation position to the neutral operation position, the exhaust resistance is significantly reduced, and when the flow rate adjustment valve 61 is rotated from the neutral operation position to the first operation position or the second operation position, it is significantly decreased. growing. As a result, in the internal combustion engine provided with the exhaust gas purification device having such a flow rate adjusting valve 61, the operating state becomes unstable or the emission deteriorates, and the operating state of the internal combustion engine can be appropriately controlled. It was gone.

On the other hand, in the flow rate adjusting valve 28 of the present invention, when the flow rate adjusting valve 28 is in the neutral operating position, the flow rate adjusting valve 28 is substantially perpendicular to the flow direction of the exhaust gas, so that the exhaust gas is Exhaust resistance is received by the flow rate adjusting valve 28. As a result, even if the operating position of the flow rate adjusting valve 28 changes, the exhaust resistance does not suddenly change significantly.
In particular, if the size of the flow rate adjusting valve 28 is set so that the exhaust resistance when the flow rate adjusting valve 28 is in the neutral operating position and the exhaust resistance of the filter 26 have substantially the same exhaust resistance, the exhaust gas receives the exhaust gas. The exhaust resistance hardly changes even if the operating position of the flow rate adjusting valve 28 changes. As a result, fluctuations in the back pressure of the internal combustion engine are almost eliminated, and the operating state of the internal combustion engine is stabilized. In the flow rate adjusting valve 28 of the present invention, the exhaust resistance changes greatly not only when the flow rate adjusting valve 28 is in the neutral operating position but also in all operating positions from the first operating position to the second operating position. There is no.

Further, as shown in FIG. 6B, in this embodiment, when the flow rate adjusting valve 28 is in the first operating position or the second operating position, the tip of the flow rate adjusting valve 28 has a port 57.
It contacts with the inner peripheral wall of c and 57d. On the other hand, in the related art, as shown in FIG. 7B, the tip of the flow rate adjusting valve 61 contacts the inner peripheral walls of the ports 62a and 62f. in this case,
A groove 63 is provided between the flow rate adjusting valve 61 and the inner peripheral wall of the port 62f.
Are formed, and the groove 63 causes turbulent flow as shown in the figure. As a result, the flow of exhaust gas becomes worse. On the other hand, the flow rate adjusting valve 28 of the present invention
Then, as shown in FIG. 6 (B), since no groove is formed as in the conventional case, no turbulent flow is generated, and therefore, the flow of exhaust gas is prevented from being deteriorated.

As described above, the control for bypassing the exhaust gas through the filter 26, that is, the neutral operating position control is also useful in an exhaust gas purification apparatus that does not include the SO _x holding material 22. For example, as one method for lowering the temperature of the filter 26, there is a method of causing exhaust gas to bypass the filter 26. Therefore,
In an exhaust emission control device that does not include the SO _x holding material 22, the flow rate adjusting valve 28 may be adjusted to the neutral operating position when the temperature of the filter 26 should be lowered. Further, the first branch exhaust pipe 25c and the second branch exhaust pipe 25d do not have to be symmetrical and the distances do not have to be equal. In the present invention, the flow rate of the exhaust gas flowing into each of the branch exhaust pipes can be made close to zero even if the branch exhaust pipes 25c and 25d are not symmetrical and are not equidistant.

Next, a modification of the first embodiment of the present invention will be described. In the first embodiment, the SO _x regeneration control is started after it is confirmed in the SO _x emission control that the flow rate adjustment valve 28 is in the neutral operating position. However, S
In the O _x regeneration control, it is necessary to raise the temperature of the SO _x holding material 22, but from the start of the SO _x regeneration control, the temperature of the SO _x holding material 22 is raised to the predetermined temperature and the SO _x is released. Takes some time. Therefore, the above-described manner with SO _x when performing reproduction control flow control valve 28 is stored SO _x member 22 becomes a neutral working position is made to heating SO _x
There will be a time lag before they can be separated.
Since the exhaust gas does not pass through the filter 26 during this time lag, the exhaust gas purification rate of the exhaust gas purification apparatus as a whole falls, so it is preferable that such a time be as short as possible.

Here, in the modified example of the first embodiment of the present invention, the position arrival time T ₁ at which the flow control valve 28 is expected to reach the neutral operating position after the neutral operating position control is started.
Is experimentally obtained in advance. Further, the temperature reaching time T ₂ expected to be required for the SO _x holding material 22 to reach the above-described predetermined temperature from the temperature of the SO _x holding material at the time when it is determined that the SO _x regeneration control should be performed is set at each temperature. Experimentally in advance. Then determining the time T ₃ as T ₃ = T ₁ -T _2. By starting the SO _x regeneration control from the start of the neutral operation position control after time T _3, the flow regulating valve 28 starts to be disengaged is SO _x substantially simultaneously stored SO _x member 22 as has reached the neutral operating position, As a result, the time during which the exhaust purification rate of the exhaust purification device as a whole falls is minimized.

SO of Modification of First Embodiment_xEmission system
The control will be described with reference to FIG. Step 142
And steps 145 to 148 are step 121 respectively.
And the description is omitted because it is the same as steps 123 to 126.
To do. In step 142, T ₃= T₁-T₂As time T₃
Is required and the process proceeds to step 142. In step 143
Resets the time counter t to zero. Then step
In 144, t ≧ T ₃It is determined whether or not t <
T₃If, then step 144 is repeated. t
≧ T₃When it becomes, it progresses to step 145.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that FIG. 10 is a view similar to FIG. 2 (C) showing the reversal type exhaust purification system 25 of the first embodiment. The configuration of the exhaust gas purification device of the second embodiment is the same as that of the first embodiment, but in the second embodiment, temperature sensors 80, 81 are used as parameter measuring means instead of pressure sensors. These temperature sensors 80 and 81 are arranged in the first branch exhaust pipe 25c and the second branch exhaust pipe 25d, respectively. Since the branch exhaust pipes 25c and 25d have a heat radiation property, these temperature sensors 80 and 81 are connected to the branch exhaust pipes 25c and 25d.
Since it is hardly affected by the temperature of d, the temperature sensor 8
0 and 81 can measure the temperature of the exhaust gas in the first branch exhaust pipe 25c and the second branch exhaust pipe 25d, respectively.

By the way, when the exhaust gas passes through the filter 26, components in the exhaust gas are oxidized, so that the filter 2
6. The temperature of the exhaust gas after passing 6 is higher than the temperature of the exhaust gas before passing. Therefore, when the temperature measured by the first temperature sensor 80 arranged in the first branch exhaust pipe 25c and the temperature measured by the second temperature sensor 81 arranged in the second branch exhaust pipe 25d are different, the inside of the filter 26 is Exhaust gas is flowing. Further, since the exhaust gas after passing through the filter 26 has a higher temperature, the exhaust gas goes from the branch exhaust pipe whose temperature is lower among the temperature sensors 80 and 81 toward the branch exhaust pipe whose higher temperature is measured. Flowing.

On the other hand, if there is no difference between the temperature measured by the first temperature sensor 80 and the temperature measured by the second temperature sensor 81, the exhaust gas has not passed through the filter 26. Therefore, when the neutral operation position control is performed and the target branch exhaust gas amount is near zero and there is no difference in the temperatures measured by the temperature sensors 80 and 81, the first branch exhaust pipe 25c and the second branch exhaust pipe The branch exhaust gas amount to 25d is the target branch exhaust gas amount.

Therefore, in the present embodiment, the target angle of the flow rate adjusting valve 28 at the neutral operating position is the first temperature sensor 8
The temperature measured by 0 and the temperature measured by the second temperature sensor 81 are substantially equal to each other, and the flow rate adjusting valve 28 is adjusted to such a target angle as the neutral operating position control.

For example, when the temperature in the first branch exhaust pipe 25c is higher than the temperature in the second branch exhaust pipe 25d, at least a part of the branch portion inflowing exhaust gas flows into the second branch exhaust pipe 25d to reverse the above. The flow rate adjusting valve 28 is slightly rotated in the second direction 56 shown in FIG. As a result, the amount of branch exhaust gas flowing into the second branch exhaust pipe 25d decreases, and the temperatures measured by the temperature sensors 80 and 81 approach each other.

On the other hand, when the temperature in the second branch exhaust pipe 25d is higher than the temperature in the first branch exhaust pipe 25c, at least a part of the branch portion inflowing exhaust gas flows into the first branch exhaust pipe 25c, and Flow control valve 2 because it is flowing in the forward direction
8 is slightly rotated in the first direction 55 shown in FIG.
As a result, the amount of branch exhaust gas flowing into the first branch exhaust pipe 25c decreases, and the temperatures measured by the temperature sensors 80 and 81 approach each other. By continuing the adjustment of the flow rate adjusting valve 28 in this way, the angle of the flow rate adjusting valve 28 always becomes the target angle, and the branch exhaust gas amount always becomes the target exhaust gas amount.

Next, the advantages of the second embodiment will be described. The pressure sensor used in the exhaust gas purification device of the first embodiment is used as a parameter measuring means in the present invention, but is usually rarely used for other purposes in the exhaust gas purification device. Therefore, if pressure sensors are used in the present invention, these sensors must be newly provided for the present invention. On the other hand, a temperature sensor is used in the second embodiment. The temperature sensor is usually used for purposes other than the parameter measuring means of the present invention, such as measuring the exhaust temperature and the temperature of the filter 26. Therefore, in the second embodiment, a temperature sensor provided for a purpose other than the present invention can be used.

In this embodiment, immediately after the neutral operating position control is started, the temperature of the exhaust gas in each branch exhaust pipe depends on the temperature immediately before the start of the control. Therefore, in the second embodiment, in order to eliminate the dependence on the temperature immediately before the control is started, the flow control valve 28 is set to a predetermined neutral operating position (e.g. Position the flow control valve 28 at an angle of 90 °),
After the elapse of a certain time, the flow rate adjusting valve 28 is adjusted based on the temperature measured by the temperature sensor described above.

Although it has been described that the flow rate adjusting valve 28 is slightly rotated, the rotation angle for rotating the flow rate adjusting valve 28 is determined according to the temperature difference between the temperatures measured by the temperature sensors 80 and 81. May be done.

Next, a third embodiment of the present invention will be described. The configuration of the exhaust gas purification device of the third embodiment is almost the same as that of the first and second embodiments, but in the third embodiment, the flow rate sensors 80, 81 are used as parameter measuring means.
Is used. The flow rate sensors 80, 81 can measure the flow direction of the fluid, but the type that can measure the flow rate of the fluid only when the fluid is flowing in a certain direction There is a type in which the flow rate of the fluid can be measured in any direction, but the direction of the fluid flow cannot be measured. Of these, in the present embodiment, a type in which the flow rate of the fluid is measured only when the fluid is flowing in a certain direction is used, and the first flow rate sensor 80 is provided from the branch portion 25b through the first branch exhaust pipe 25c. The second flow sensor 8 is arranged so that the flow rate of the exhaust gas flowing into the filter 26 can be measured.
1 is arranged so that the flow rate of the exhaust gas flowing into the filter 26 from the branch portion 25b through the second branch exhaust pipe 25d can be measured.

When the flow rate sensors 80 and 81 are arranged in this way, if the exhaust gas does not pass through the filter 26, the amount of exhaust gas measured by the flow rate sensors 80 and 81 is close to zero. Therefore, when the neutral operation position control in which the target branch exhaust gas amount is near zero is executed and the exhaust gas amount measured by both the flow rate sensors 80, 81 is near zero, the first branch exhaust pipe 25c and the first branch exhaust pipe 25c and the first branch exhaust pipe 25c. The amount of branch exhaust gas to the two-branch exhaust pipe 25d is the target amount of branch exhaust gas. That is, the target angle of the flow rate adjusting valve 28 is an angle at which the exhaust gas amount measured by both the flow rate sensors 80 and 81 becomes close to zero, and the flow rate adjusting valve 28 is set to such a target angle in the neutral operating position control. It can be rotated.

Therefore, for example, when the flow of the exhaust gas is detected by the first flow rate sensor 80, at least a part of the exhaust gas flowing into the branch portion flows into the first branch exhaust pipe 25c and flows in the forward direction. From the flow control valve 28
Is rotated in the first direction 55 shown in FIG. 9 in accordance with the flow rate measured by the first flow rate sensor 80. As a result, the amount of branch exhaust gas flowing into the first branch exhaust pipe 25c decreases, and the flow rate of exhaust gas measured by the first flow sensor 80 decreases.

On the other hand, when the flow of the exhaust gas is detected by the second flow rate sensor 81, at least a part of the exhaust gas flowing into the branch portion flows into the second branch exhaust pipe 25d and flows in the opposite direction. The flow rate adjusting valve 28 is rotated in the second direction 56 shown in FIG. 9 according to the flow rate measured by the second flow rate sensor 81. As a result, the amount of branch exhaust gas flowing into the second branch exhaust pipe 25d decreases, and the flow rate of exhaust gas measured by the second flow sensor 81 decreases. By continuing the adjustment of the flow rate adjusting valve 28 in this way, the angle of the flow rate adjusting valve 28 always becomes the target angle, and the branch exhaust gas amount always becomes the target exhaust gas amount.

In this embodiment, the flow rate of the exhaust gas flowing in each of the branch exhaust pipes 25c and 25d is directly measured. The angle of the adjusting valve 28 can be accurately and quickly positioned at an angle at which the branch exhaust gas amount is near zero. Further, even when the target branch exhaust gas amount is not near zero, the branch exhaust gas amount can be accurately set as the target branch exhaust gas amount.

In the third embodiment, the flow rate sensor 80,
The rotation angle at which the flow rate adjusting valve 28 should be rotated is determined according to the flow rate measured by 81. This rotation angle is not limited to the flow rate measured by the flow rate sensor 85, but also the branch portion inflow exhaust gas. It also depends on the quantity, ie the quantity of exhaust gas emitted from the internal combustion engine. Therefore, when determining the rotation angle, the rotation angle is determined by correcting the flow rate measured by the flow rate sensor 85 according to a parameter relating to the amount of exhaust gas discharged from the internal combustion engine such as the engine speed. It is preferably used.

Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, NO is used as the parameter measuring means.
One of various sensors, such as an _x sensor, an HC sensor, an A / F sensor, or an O ₂ sensor, which measures a component contained in exhaust gas is used. In the following, the NO _x sensors 80 and 81 will be described as an example, but other sensors can be used as well.

By the way, when the operating state of the internal combustion engine changes, the concentration of NO _x contained in the exhaust gas also changes. Therefore, if the exhaust gas flows in the branch exhaust pipes 25c and 25d, the NO _x concentration measured by the NO _x sensors 80 and 81 also changes. On the contrary, if the NO _x concentration measured by each of the NO _x sensors 80 and 81 does not change even if the operating state of the internal combustion engine changes, the exhaust gas will be the branch exhaust pipe 25.
It does not flow in c and 25d, and the amount of branch exhaust gas is near zero. Further, when the exhaust gas passes through the filter 26, most of NO _x is reduced and disappears. Thus, NO _x is not detected from one of the NO _x sensor 80 and 81 when passing through the filter 26 is the exhaust gas, the other of the NO _x
Only concentration of NO _x to be measured to the sensor changes. In this case, the exhaust gas flowing into the branch portion flows into the branch exhaust pipe in which the NO _x sensor on the side where the NO _x concentration changes when the operating state of the internal combustion engine changes, and NO _x where NO _x is not detected is detected.
It returns from the branch exhaust pipe in which the _Ox sensor is arranged to the branch portion 25b.

From the above, in the present embodiment, the target angle of the flow rate adjusting valve 28 at the neutral operating position is detected when the operating state of the internal combustion engine is detected by the load sensor 52, the crank angle sensor 53, etc. and the operating state changes. Even both N
The angle is such that the NO _x concentration measured by the O _x sensors 80 and 81 hardly changes, and the flow rate adjusting valve is adjusted to such a target angle as the neutral position control.

For example, when the NO _x concentration measured by the first NO _x sensor 80 changes when the operating state of the internal combustion engine changes, at least a part of the exhaust gas flowing into the branch portion flows to the first branch exhaust pipe 25c. Since it flows in and flows in the forward direction, the flow rate adjusting valve 28 is slightly rotated in the first direction 55 shown in FIG. On the contrary, when the NO _x concentration measured by the second NO _x sensor 81 changes when the operating state of the internal combustion engine changes, at least a part of the exhaust gas flowing into the branch part flows into the second branch exhaust pipe 25d. As a result, the flow rate adjusting valve 28 is slightly rotated in the second direction 56 shown in FIG. By continuing the adjustment of the flow rate adjusting valve 28 in this way, the angle of the flow rate adjusting valve 28 always becomes the target angle, and the branch exhaust gas amount always becomes the target branch exhaust gas amount.

A fifth embodiment of the present invention will be described with reference to FIG. Note that FIG. 10 corresponds to FIG.
It is a figure similar to. The configuration of the exhaust emission control device of the fifth embodiment is similar to that of the third embodiment, but in the fifth embodiment, only one flow rate sensor 85 is arranged on one of the first branch exhaust pipe 25c and the second branch exhaust pipe 25d. To be done.

In this embodiment, the flow rate sensor 85 is a type of flow rate sensor capable of detecting not only the flow rate but also the flow direction of the exhaust gas passing through the flow rate sensor 85. Which of the first branch exhaust pipe 25c and the second branch exhaust pipe 25d is flowing, that is, in which of the forward direction and the reverse direction the exhaust gas is flowing through the branch exhaust pipes 25c, 25d and the filter 26. Can be detected.

In this case, since the flow rate sensor 85 plays the role of the two flow rate sensors 80 and 81 in the third embodiment, the angle of the flow rate adjusting valve 28 is adjusted as in the third embodiment.
As a result, the branch exhaust gas amount can be made the target branch exhaust gas amount.

However, many flow rate sensors can measure the flow rate, but cannot measure the flow direction of the exhaust gas. In this case, the direction in which the flow rate adjusting valve 28 should be rotated cannot be determined, and thus the angle of the flow rate adjusting valve 28 cannot be adjusted as in the fifth embodiment described above. Therefore, when using such a flow rate sensor 85, the control shown in the following modified example is performed.

In the modified example of the fifth embodiment, the target angle of the flow rate adjusting valve 28 in the neutral operating position is such that the flow rate measured by the flow rate sensor 85 is near zero,
As the neutral operating position control, the flow rate adjusting valve 28 is adjusted to such a target angle.

Therefore, when the flow rate measured by the flow rate sensor 85 is not near zero, the flow rate adjusting valve 28 is rotated in the first direction 55 or the second direction 56 by the rotation angle corresponding to the measured flow rate. . As a result of rotating the flow rate adjusting valve 28, when the flow rate measured by the flow rate sensor 85 decreases but does not become close to zero, the flow rate adjusting valve 28 is rotated by the rotation angle according to the measured flow rate the previous time. Rotate in the same direction as the moving direction. On the other hand, when the flow rate measured by the flow rate sensor 85 increases as a result of rotating the flow rate adjusting valve 28, the flow rate adjusting valve 28 is rotated in the opposite direction to the previous rotating direction by the rotation angle corresponding to the measured flow rate. Rotate to.
By continuing the adjustment of the flow rate adjusting valve 28 in this way, the angle of the flow rate adjusting valve 28 always becomes the target angle, and the branch exhaust gas amount always becomes the target exhaust gas amount.

Next, the neutral operating position control routine of the modified example of the fifth embodiment will be described with reference to FIG. In the following description, φ indicates the rotation angle of the flow rate adjusting valve 28. For example, when the value is positive, it rotates in the first direction 55, and when the value is negative, it rotates in the second direction 56. . When the neutral operating position control is started, first, in step 161, a counter n indicating the number of times that steps 162 to 168 are repeated is set to 0, and when the counter is n, the exhaust gas amount V _n measured by the flow rate sensor 85 is set. ,
Particularly in this case, V ₀ is acquired from the flow rate sensor 85. Further, in step 161, the angle θ of the flow rate adjusting valve 28 is set to 90 °, and the rotation angle φ _n for rotating the flow rate adjusting valve 28 is calculated as φ ₀ = kV ₀ . This constant k is
It is a constant for calculating the rotation angle of the flow rate adjusting valve 28 required to bring the flow rate close to zero with respect to the flow rate measured by the flow rate sensor 85. The value is such that an angle smaller than the required rotation angle is calculated. Next, the flow rate adjusting valve 28 is rotated by the calculated φ ₁ .

Next, at step 162, n + 1 is set as a new n, and the exhaust gas amount V _{n at the} new counter _n is acquired from the flow rate sensor 85. Next, at step 163, it is judged if V _n ≈0 or not. If V _n ≈0, then the routine proceeds to step 168. On the other hand, if V _n ≈b is not satisfied in step 163, the process proceeds to step 164, and it is determined whether or not V _n <V _n-1 . When V _n <V _n−1 in step 164, the process proceeds to step 165. In step 165, φ _n-1
kV _n / | φ _n-1 | is set as a new φ _n, and step 167 is performed.
Go to. On the other hand, if V _n ≧ V _n−1 in step 164, the process proceeds to step 166. At step 166, -φ _n-1 kV _n / | φ _n-1 | is set as a new φ _n, and the routine proceeds to step 167.

At step 167, the flow control valve is set to the angle φ _n.
It is rotated only by that amount, and the process proceeds to step 168. In step 168, it is determined whether a condition similar to the ending condition of the neutral operating position control in step 106 of FIG. 4 is satisfied, and if the ending condition of the neutral operating position control is not satisfied, the process proceeds to step 162. Will be returned. On the other hand, step 1
If the condition for ending the neutral operating position control is satisfied at 68, the neutral operating position control routine ends.

Next, a sixth embodiment will be described. In the present embodiment, NO _x sensor in place of the flow sensor 85 of the fifth embodiment, HC sensor, is one kind of sensor of the various sensors such as A / F sensor or O ₂ sensor is used. In the following, the NO _x sensor 85 is connected to the second branch exhaust pipe 25.
The case of arranging it in d will be described, but the same applies to the case of arranging in the first branch exhaust pipe 25c and the case of using other sensors.

When performing the neutral operating position control of the flow rate adjusting valve 28 with the above-described configuration, there are two conditions under which it can be said that the actual branch exhaust gas amount is the target branch exhaust gas amount (that is, near zero). The conditions for First, NO the concentration of the NO _x discharged from the internal combustion engine changes the operating state of the internal combustion engine as described in the fourth embodiment is measured by the NO _x sensor 85 also vary _{The x} concentration does not change. The second condition is that the measured NO _x concentration is relatively higher than zero. NO _x measured
When the concentration is near zero, the amount of branch exhaust gas is near zero, and after the filter has passed, the exhaust gas is flowing so as to flow into the branch exhaust pipe where the NO _x sensor is arranged. There are two possible ways to measure NO _x.
It is impossible to determine whether the density is near zero. Therefore, when the measured NO _x concentration is near zero, the branch exhaust gas amount cannot be said to be the target exhaust gas amount even if the first condition is satisfied. Therefore, in the present embodiment, the flow rate adjusting valve 28 that satisfies these two conditions is
Is the target angle of the flow rate adjusting valve 28.

In actual control, when the NO _x concentration measured by the NO _x sensor 85 is near zero, as described above, the branch portion inflow exhaust gas flows into the first branch exhaust pipe 25c and flows in the forward direction. And the branch exhaust pipe 25c,
It is considered that the exhaust gas is not flowing through 25d and the filter 26. However, since neither of them can be specified, the flow rate adjusting valve 28 is slightly moved in the first direction 55 assuming that the branch portion inflowing exhaust gas is flowing in the forward direction. Rotate to.

Also, NO_xMeasured by sensor 85
NO_xThe operating condition of the internal combustion engine when the concentration is not near zero
NO measured when changes_xWhen the concentration changes
In this case, the exhaust gas flowing into the branch flows into the second branch exhaust pipe 25d.
Then it is flowing in the opposite direction. Therefore, in this case,
The regulating valve 28 is slightly rotated in the second direction 56. This
By continuing to adjust the flow rate adjusting valve 28,
The angle θ of the adjusting valve 28 is NO _xMeasured by sensor 85
NO_xIf the concentration is not near zero and the internal combustion engine is operating
NO measured even when the condition changes_xDo not change the concentration
Angle, that is, the target angle, and the amount of branch exhaust gas
It becomes the standard branch exhaust gas amount.

Next, the neutral operating position control routine of the sixth embodiment will be described with reference to FIG. First, in step 181, it is measured by the NO _x sensor 85 NO _x
It is determined whether the density is near zero. When it is determined that the NO _x concentration is near zero, the process proceeds to step 182. In step 182, the flow rate adjusting valve 28 is slightly rotated in the first direction 55, and the process proceeds to step 186. On the other hand, if it is determined in step 181 that the NO _x concentration is not near zero, the process proceeds to step 183. In step 183, it is determined whether the operating state of the internal combustion engine has changed, and if it is determined that the operating state has not changed, step 183 is repeated.

If it is determined in step 183 that the operating condition has changed, the process proceeds to step 184,
It is determined whether or not the NO _x concentration has changed with the change in the operating state of the internal combustion engine. NO in step 184
proceeds to step 186 _{if x} concentration is determined not to have changed, when it is determined that the concentration of NO _x is changed, the process proceeds to step 185. At step 185, the flow rate adjusting valve 28 is slightly rotated in the second direction 56, and the routine proceeds to step 186. In step 186, it is determined whether or not a condition similar to the ending condition of the neutral operating position control in step 106 of FIG. 4 is satisfied. If the condition is not satisfied, the process returns to step 181. On the other hand, if the condition is satisfied in step 186, the neutral operating position control routine is ended.

Finally, a seventh embodiment of the present invention will be described with reference to FIG. In this embodiment, a two-branch exhaust purification device 90 shown in FIG. 13 is provided instead of the reversal exhaust purification device 25.

As shown in FIG. 13, the two-branch exhaust purification device 90 includes an upstream exhaust pipe (upstream exhaust passage) 90a,
Branch portion 90b and first branch exhaust pipe (first branch exhaust passage)
90c and second branch exhaust pipe (second branch exhaust passage) 90d
A casing 90e (hereinafter, referred to as a holding casing) that holds a particulate filter (hereinafter, referred to as a filter) 91, a downstream side exhaust pipe (downstream side branch exhaust passage) 90f, and a filter 91.

One end of the upstream side exhaust pipe 90a is connected via the exhaust pipe 24 to the SO _x holding material 22 arranged upstream of the two-branch exhaust purification device 90. Therefore, the exhaust gas flows into the two-branch exhaust purification device 90 from the upstream side exhaust pipe 90a. The other end of the upstream exhaust pipe 90a branches into a first branch exhaust pipe 90c and a second branch exhaust pipe 90d at a branch portion 90b. The upstream side exhaust pipe 90a and the first branch exhaust pipe 90c are located on a substantially straight line. A holding casing 90e is arranged on the first branch exhaust pipe 90c, and the filter 91 is held in the holding casing. The tip of the second branch exhaust pipe 90d merges with the first branch exhaust pipe 90c downstream of the filter 91.

A flow rate adjusting valve 92 is provided at the branching portion 90b. The flow rate adjusting valve 92 continuously swings around the connecting portion between the first branch exhaust pipe 90c and the second branch exhaust pipe 90d as shown in FIG. 13, and flows into the branch portion 90b from the upstream side exhaust pipe 90a. The flow direction of the exhaust gas, that is, the angle of the flow rate adjusting valve 92 (hereinafter referred to as the angle of the flow rate adjusting valve 92) θ with respect to the axes of the upstream side exhaust pipe 90a and the first branch exhaust pipe 25c changes. The angle θ of this flow rate adjusting valve 92
When is larger, the amount of exhaust gas flowing into the first branch exhaust pipe 90c is smaller and the amount of exhaust gas flowing into the second branch exhaust pipe 90d is larger. Conversely, if the angle θ of the flow rate adjusting valve 92 is reduced, the amount of exhaust gas flowing into the first branch exhaust pipe 90a increases and the amount of exhaust gas flowing into the second branch exhaust pipe 90d decreases. Further, the upstream side exhaust pipe 90a
A first NO _x sensor 93 and a second NO _x sensor 94 are arranged in the first branch exhaust pipe 90c upstream of the filter 91.

Two-branch exhaust purification device 9 having such a configuration
At 0, for example, when the NO _x retained in the filter 91 is released, the exhaust gas amount that flows into the filter 91, that is, the first branch exhaust pipe 90a may be the target branch exhaust gas amount. In such a case, the flow rate adjustment valve 92
The angle θ of is adjusted as follows.

Here, according to the two-branch exhaust purification unit 90 of this embodiment, the NO _x amount in the exhaust gas flowing through the upstream exhaust pipe 90a is measured by the first NO _x sensor 93, and the first branch exhaust gas is obtained. The amount of NO _x in the exhaust gas flowing in the pipe 90c is measured by the second NO _x sensor 94. The amount of NO _{x in} the first branch exhaust pipe 90c with respect to the amount of NO _x in the upstream exhaust pipe 90a is proportional to the amount of exhaust gas flowing in the first branch exhaust pipe 90c with respect to the amount of exhaust gas flowing in the upstream exhaust pipe 90a. Therefore, by measuring these NO _x amounts, the ratio of the exhaust gas amounts flowing in the exhaust pipes 90a and 90c can be obtained. On the other hand, the amount of exhaust gas flowing into the upstream exhaust pipe 90a can be calculated from the operating state of the internal combustion engine. Therefore, the amount of exhaust gas flowing into the first branch exhaust pipe 25c can be calculated from the ratio of the amount of exhaust gas flowing through the exhaust pipes 90a and 90c and the amount of exhaust gas flowing into the upstream exhaust pipe 90a. .

Therefore, when the amount of exhaust gas flowing into the first branch exhaust pipe 90c should be the target amount of branch exhaust gas,
When the calculated exhaust gas amount is smaller than the target branch exhaust gas amount, the angle θ of the flow rate adjusting valve 92 is made slightly smaller, and when it is larger than the target branch exhaust gas amount, the angle θ of the flow amount adjusting valve 92 is made slightly smaller. Increase to. By repeating such an operation, the amount of exhaust gas flowing into the first branch exhaust pipe 90a always becomes the target exhaust gas amount.

The advantages of this embodiment will be described. The NO _x sensor used in this embodiment is, for example, a filter 9
It is also used for applications other than measuring the branch exhaust gas amount, such as for estimating the amount of NO _x retained at 1. Therefore, in the present embodiment, it is possible to use a sensor used for a purpose other than measuring the amount of branch exhaust gas.

In the above embodiment, the upstream side exhaust pipe 90
Although the NO _x sensors 93 and 94 are arranged in a and the first branch exhaust pipe 90c upstream of the filter 91, they may be arranged in different positions. More specifically, the upstream exhaust pipe 90
a and the first branch exhaust pipe 90c upstream of the filter 91
The second branch exhaust pipe 90d and the first branch exhaust pipe 90c downstream of the confluence of the second branch exhaust pipe 90d may be arranged at any two positions. As a result, the position where the sensor is arranged can be selected from various positions, which makes it easier to use the sensor used for purposes other than measuring the branch exhaust gas amount.

In the present embodiment, instead of the NO _x sensor, an HC sensor, an A / F sensor or an O ₂ sensor may be used, or a pressure sensor, a flow rate sensor, a temperature sensor, etc. may be used.

[0104]

According to the present invention, the amount of exhaust gas flowing into the branch exhaust passage can always be precisely maintained at the target exhaust gas amount, so that it flows into the filter arranged in the branch exhaust passage. The amount of exhaust gas can be easily and precisely controlled to the target amount.

[Brief description of drawings]

FIG. 1 is a diagram of an internal combustion engine including an exhaust emission control device according to a first embodiment of the present invention.

FIG. 2 is a diagram of an exhaust emission control device of a first embodiment of the present invention.

FIG. 3 is an enlarged view of a branch portion of the exhaust emission control device.

FIG. 4 is a flowchart of neutral operating position control of the first embodiment.

FIG. 5 is a flowchart of SO _x emission control according to the first embodiment.

FIG. 6 is a diagram showing an operation of the flow rate adjusting valve of the present invention.

FIG. 7 is a diagram showing an operation of a conventional flow rate adjusting valve.

FIG. 8 is a flowchart of SO _x emission control according to a modified example of the first embodiment.

FIG. 9 is a diagram of an exhaust emission control device of second to fourth embodiments.

FIG. 10 is a diagram of an exhaust emission control device of fifth and sixth embodiments.

FIG. 11 is a flowchart of neutral operating position control of the fifth embodiment.

FIG. 12 is a flowchart of neutral operating position control of the sixth embodiment.

FIG. 13 is a diagram of an exhaust emission control device of a seventh embodiment.

[Explanation of symbols]

22 ... SO _x holding agent 23 ... Casing 25 ... Reversing type exhaust gas purification device 26 ... Particulate filter 27 ... Flow control valve step motor 28 ... Flow control valves 49, 50 ... Pressure sensor

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) F01N 3/08 F01N 3/08 A 3/18 3/18 B F 3/24 3/24 R F02D 41 / 04 355 F02D 41/04 355 43/00 301 43/00 301E 301T 45/00 314 45/00 314Z // B01D 46/44 B01D 46/44 (72) Inventor Yoshimitsu Hedda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (72) Inventor Kazuhiro Ito 1 Toyota-cho, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (72) Inventor Takamitsu Asanuma 1 Toyota-cho, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Koichi Kimura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Koichiro Nakatani 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Inside Motor Corporation (72) Inventor Yasuaki Nakano 1 Toyota-cho, Toyota City, Aichi Prefecture Toyota Motor Corporation Inside (72) Inventor Akira Akira, Toyota-cho, Toyota City, Aichi Prefecture F Term in Toyota Motor Corporation (reference) 3G084 AA01 AA03 AA04 BA05 BA08 BA09 BA13 BA15 BA19 BA20 BA24 DA10 DA27 EA11 EB01 EB11 EC07 FA00 FA10 FA18 FA27 FA28 FA29 FA33 FA38 3G090 AA01 BA01 CB23 DA02 DA03 DA04 DA09 DA12 EA01 EA02 EA05 EA06 3G091 AA02 AA10 AA11 AA18 AA28 AB08 AB13 BA00 BA11 BA20 BA31 CA12 CA13 CB02 CB03 CB07 CB08 DA01 DA02 DA05 DB10 EA00 EA01 EA03 EA17 EA21 EA31 EA32. NE13 NE15 PA17B PA17Z PD01B PD01Z PD02B PD02Z PD11B PD11Z PD14B PD14Z PD16B PD16Z PE01B PE01Z PE03B PE03Z PF03B PF03Z 4D058 NA01 NA04 NA05 QA01 QA03 QA19 QA23 SA08 TA02

Claims (12)

[Claims] 1. An upstream exhaust passage communicating with a combustion chamber of an internal combustion engine, wherein the upstream exhaust passage branches into at least two branched exhaust passages at a branch portion, and at least one of the branched exhaust passages is particulated. A filter is arranged, a flow rate adjusting valve whose operating position is continuously adjustable is arranged in the branch portion, and exhaust gas flowing into at least one branch exhaust passage by adjusting the operating position of the flow rate adjusting valve. An exhaust emission control device capable of adjusting the amount, comprising parameter measuring means for measuring a parameter relating to exhaust gas, and the at least one branch based on the parameter measured by the parameter measuring means. The amount of exhaust gas flowing into the exhaust passage is calculated so that the calculated exhaust gas amount becomes the target exhaust gas amount. Exhaust gas purification apparatus designed to adjust the operating position of the amount regulation valve. 2. A tip end portion of the at least one branch exhaust passage is connected to the branch portion by returning to the branch portion, and at least a part of exhaust gas flowing into the branch portion from the upstream side exhaust passage depending on an operating position of the flow rate adjusting valve. 2. The exhaust emission control device according to claim 1, wherein the exhaust gas can flow through the at least one branch exhaust passage in one direction or in the opposite direction, and then can flow out to the remaining branch exhaust passages through the branch portion. . 3. The exhaust emission control device according to claim 2, wherein the target exhaust gas amount is substantially zero. 4. The flow rate adjusting valve is a valve in which when the operating position of the flow rate adjusting valve changes, the angle of the flow rate adjusting valve with respect to the flow direction of the exhaust gas flowing into the branch portion from the upstream exhaust passage changes. The branching portion has a port communicating with the upstream side exhaust passage, and the angle of the flow rate adjusting valve is larger than the angle when the flow rate adjusting valve is in contact with the inner peripheral wall of the port. Exhaust purification device. 5. The flow rate adjusting valve is a valve in which when the operating position of the flow rate adjusting valve changes, the angle of the flow rate adjusting valve with respect to the flow direction of the exhaust gas flowing into the branch portion from the upstream exhaust passage changes. When the flow rate control valve is perpendicular to the flow direction of the exhaust gas, the amount of the exhaust gas flowing into the at least one branch exhaust passage becomes close to zero, and when the target exhaust gas amount is substantially zero, the exhaust gas The exhaust emission control device according to claim 3 or 4, wherein the flow rate adjusting valve is substantially perpendicular to the flow direction of the. 6. The upstream side exhaust passage, the branch portion,
One end of the at least one branch exhaust passage, the other end of the at least one branch exhaust passage, and the first port, the second port, the third port, and the fourth port leading to the second branch exhaust passage When the flow rate adjusting valve is held at a position such that all the exhaust gas flowing from the upstream side exhaust passage into the branch portion flows into the at least one branch exhaust passage, the flow rate adjusting valve has an inner peripheral wall of the second port. The exhaust emission control device according to any one of claims 2 to 5, which is in contact with the inner peripheral wall of the third port. 7. An SO _x holding material is disposed in the upstream side exhaust passage, the SO _x holding material holds SO _x in the exhaust gas when the air-fuel ratio of the exhaust gas is lean, and the SO _x holding material holds the SO _x in the exhaust gas. 4. When the temperature of the SO _x holding material exceeds a predetermined temperature, the held SO _x can be released, and when the SO _x is released, the target exhaust gas amount is substantially zero. Exhaust purification device. 8. The parameter measuring means comprises two pressure sensors, one of which is arranged on each side of the particulate filter in the at least one branch exhaust passage. Exhaust gas purification device according to one. 9. The parameter measuring means comprises two temperature sensors, one of which is arranged on each side of the particulate filter in the at least one branch exhaust passage. Exhaust gas purification device according to one. 10. The parameter measuring means comprises a flow rate sensor, a NO _x sensor, an HC sensor, an A / F sensor and an O ₂ sensor.
The exhaust emission control device according to claim 2, wherein the exhaust purification device is one of the sensors, and the sensor is disposed in the branch exhaust passage. 11. The branch exhaust passage comprises a first branch exhaust passage in which a particulate filter is arranged and a second branch exhaust passage, and a tip of the second branch exhaust passage is at a confluence portion downstream of the branch portion. Merging with the one-branch exhaust passage, an upstream exhaust passage upstream of the branch portion, a first branch exhaust passage between the branch portion and the joining portion, a second branch exhaust passage between the branch portion and the joining portion, The exhaust emission control device according to claim 1, wherein the parameter measuring means is disposed in at least two of the branch exhaust passages downstream of the merging portion. 12. The exhaust gas parameter other than the flow rate of the exhaust gas is measured by the parameter measuring means.
The exhaust emission control device according to.