JPH08338320A - Exhaust emission control device - Google Patents

Abstract

PURPOSE: To make a particulate filter simple in structure, and small in size, reduce particulates contained in exhaust gas circulated in a suction system, and thereby enhance the durability of an engine. CONSTITUTION: An intake pipe 12 is connected to an engine 10 via an intake manifold 11, and an exhaust pipe 14 is connected to the engine via an exhaust manifold 13. An EGR passage 16 branched out of the exhaust pipe is joined to the intake pipe, and a flow rate control valve 16 regulates the flow rate of exhaust gas circulated from the EGR passage out of the intake pipe. A controller 24 controls the EGR flow rate control valve based on the detected outputs of a rotation sensor 22 detecting the revolution speed of the engine, and of a load sensor detecting the load of the engine. An oxidation catalyst 18 and a particulate filter 19 are disposed in the EGR passage in order from the upstream side of exhaust gas, and the particulate filter is so constituted as to also function as an oxidation catalyst because active metals are suppored by the particulate filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for purifying mainly nitrogen oxides (hereinafter referred to as NOx) contained in engine exhaust gas. More specifically, the present invention relates to an exhaust gas purification device that uses an exhaust gas recirculation device (hereinafter referred to as an EGR (Exhaust Gas Recirculation) device).

[0002]

2. Description of the Related Art Conventionally, as an exhaust gas purifying device of this type,
An EGR passage is provided to connect the exhaust system and the intake system of the engine, a reburning filter for reburning and removing particulates in the exhaust gas is provided in the EGR passage, and a reburning filter is further provided in the EGR passage downstream of the exhaust gas from the filter. EGR provided with a cooling device that cools exhaust gas that has become hot by burning
An apparatus has been disclosed (Shokaisho 61-101663).
In this device, a heating means such as a nichrome wire is provided in the reburning filter, and the particulate matter in the exhaust gas is reburned and removed by this heating means, so that the purified exhaust gas containing no particulates can be recirculated to the engine. As a result, the abrasion of the engine sliding portion due to the above particulates can be prevented and the amount of carbon mixed in the lubricating oil of the engine can be reduced, so that the durability of the engine and the life of the lubricating oil can be improved. Further, since low-temperature exhaust gas can be recirculated to the engine, NOx emitted from the engine can be significantly reduced.

[0003]

However, the above-mentioned conventional E
In the GR device, heating means must be provided in the reburning filter, which causes a problem that the filter becomes complicated and becomes large in size. An object of the present invention is to provide an exhaust gas purifying apparatus capable of improving the durability of an engine by reducing the particulates in the exhaust gas recirculated to the intake system, which can be downsized with a relatively simple structure of the particulate filter. Especially. Another object of the present invention is to provide an exhaust gas purifying apparatus that can prevent the generation of sulfate by controlling the temperature of the exhaust gas flowing into the oxidation catalyst to a predetermined value or less and that does not reduce the combustion efficiency in the engine.

[0004]

The structure of the present invention for achieving the above object is shown in FIGS. 1, 2 and 4 corresponding to the embodiment.
Also, description will be made with reference to FIGS. The first aspect of the present invention is
An intake pipe 12 that is connected to an intake manifold 11 of the engine 10 to supply air to the engine 10 as shown in FIG.
An exhaust pipe 14 that is connected to an exhaust manifold 13 of the engine 10 and that exhausts the exhaust gas of the engine 10 to the atmosphere;
EGR passage 16 that branches from 4 and joins the intake pipe 12 or the intake manifold 11, and the intake pipe 1 from the EGR passage 16
2 or an EGR flow control valve 17 capable of adjusting the flow rate of exhaust gas recirculated to the intake manifold 11, a rotation sensor 22 for detecting the rotation speed of the engine 10, a load sensor 23 for detecting the load of the engine 10, and a rotation sensor. 22 is an improvement of the exhaust gas purifying apparatus including a controller 24 that controls the EGR flow rate control valve 17 based on the detection outputs of the load sensor 23 and the load sensor 23. The characteristic structure is that the EGR passage 1
In FIG. 6, an oxidation catalyst 18 and a particulate filter 19 are provided in order from the exhaust gas upstream side, and the particulate filter 19 is configured to support an active metal so that the particulate filter 19 also functions as an oxidation catalyst. .

Further, as shown in FIG. 2 or 4, a heat exchanger 41 or 61 provided in the EGR passage 16 or 66 on the exhaust gas upstream side of the oxidation catalyst 18 and capable of exchanging heat with the exhaust gas flowing through the EGR passage 16 or 66. And the heat exchanger 41 or 6
1 to supply the refrigerant 68 to lower the temperature of the exhaust gas flowing through the EGR passage 16 or 66.
And a temperature sensor 49 provided in the EGR passage 16 or 66 on the exhaust gas upstream side of the oxidation catalyst 18 to detect the temperature of the exhaust gas flowing through the EGR passage 16 or 66, and the controller 24 detects the temperature based on the detection output of the temperature sensor 49. It is preferably arranged to control the coolant supply means 42 or 62. In addition, as shown in FIG. 7 or 8, the EGR passage 1 on the exhaust gas downstream side of the particulate filter 19
6 or 66 and a heat exchanger 71 or 81 capable of exchanging heat with the exhaust gas flowing through the EGR passage 16 or 66, and the temperature of the exhaust gas flowing through the EGR passage 16 or 66 by supplying a refrigerant to the heat exchanger 71 or 81. Is provided in the EGR passage 16 or 66 on the exhaust gas downstream side of the particulate filter 19 and the refrigerant supply means 72 or 82 for reducing the E
A temperature sensor 79 for detecting the temperature of the exhaust gas flowing through the GR passage 16 or 66 may be provided, and the controller 24 may be configured to control the refrigerant supply means 72 or 82 based on the detection output of the temperature sensor 79.

As shown in FIG. 2 or 7, the refrigerant is air, and the refrigerant supply means 42 or 72 is the heat exchanger 4
Duct 43 or 73 connected to 1 or 71, a blower 44 or 74 for sending air to the heat exchanger 41 or 71 through the duct 43 or 73, and a duct 43 or 73 provided in the duct 43 or 73 An air flow control valve 45 or 75 capable of adjusting the flow rate of air, and the controller 24 is configured to control the blower 44 or 74 and the air flow control valve 45 or 75 based on the detection output of the temperature sensor 49 or 79. You can also do it. Further, as shown in FIG. 4 or 8, the refrigerant 68 is water, and the refrigerant supply means 62 or 82 connects the cooling water pipe 63 or 83 connected to the heat exchanger 61 or 81 and the cooling water pipe 63 or 83. And a cooling water pump 64 for pumping water 68 to the heat exchanger 61 or 81 via the cooling water pipe 63 or 83.
Or the cooling water flow rate control valve 65 or 85 capable of adjusting the flow rate of the water 68 flowing through 83, and the controller 24 controls the cooling water flow rate control valve 65 or 85 or the cooling water flow rate based on the detection output of the temperature sensor 49 or 79. It can also be configured to control the control valve 65 or 85 and the cooling water pump 64.

In the second aspect of the present invention, as shown in FIG. 9, the exhaust pipe 14 is provided with an oxidation catalyst 18 and a particulate filter 19 in order from the exhaust gas upstream side, and the particulate filter 19 carries active metal and is particulate. The particulate filter 19 is configured to function also as an oxidation catalyst, and the EGR passage 16 is branched from the exhaust pipe 14 on the exhaust gas downstream side of the particulate filter 19. Further, as shown in FIG. 10, a heat exchanger 71 provided in the EGR passage 16 and capable of exchanging heat with the exhaust gas flowing through the EGR passage 16, and a refrigerant is supplied to the heat exchanger 71 to supply EGR.
The refrigerant supply means 72 for lowering the temperature of the exhaust gas flowing through the passage 16 and the EGR passage 1 provided in the EGR passage 16
6 and a temperature sensor 79 for detecting the temperature of the exhaust gas flowing therethrough, and the controller 24 preferably controls the refrigerant supply means 72 based on the detection output of the temperature sensor 79.

[0008]

In the exhaust gas purifying apparatus shown in FIG. 1, when the EGR flow control valve 17 is opened, the exhaust gas is first introduced into the oxidation catalyst 18, and the oxidation catalyst 18 causes the unburned fuel content of the particulates in the exhaust gas to be removed. SOF (So
luble Organic Fracion) is oxidized. Next, this exhaust gas is introduced into the particulate filter 19, and the soot among the particulates in the exhaust gas is collected. As a result, the particulates in the exhaust gas recirculated to the intake pipe 12 or the intake manifold 11 are significantly reduced. Further, the soot deposited on the filter 19 is oxidized by Pt carried on the filter 19.

In the exhaust gas purifying apparatus shown in FIG. 2, the temperature of the exhaust gas introduced into the oxidation catalyst 18 is controlled by the heat exchanger 41 to be equal to or lower than a predetermined temperature at which sulfate is not generated, so that the intake pipe 12 or the intake manifold 11 is controlled. The sulfate in the recirculated exhaust gas is reduced. The soot deposited on the filter 19 is carried by the filter 19 and is oxidized by an active metal that exhibits catalytic activity even at a low temperature below the predetermined temperature.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. <Example 1> As shown in FIG. 1, a diesel engine 1
An intake pipe 12 is connected to the 0 intake port via an intake manifold 11, and an exhaust pipe 14 is connected to the exhaust port via an exhaust manifold 13. The middle of the exhaust pipe 14 and the middle of the intake pipe 12 are connected by an EGR passage 16, that is, the EGR passage 16 branches from the exhaust pipe 14,
It joins the intake pipe 12. In addition, this E
An EGR flow rate control valve 17 capable of adjusting the flow rate of exhaust gas recirculated from the GR passage 16 to the intake pipe 12 is provided. The control valve 17 includes a valve body 17a that opens and closes the EGR passage 16,
The valve unit 17a has a drive unit 17b configured by a stepping motor or the like that drives the valve body 17a so that the EGR passage 16 has a predetermined opening degree.

An oxidation catalyst 18 and a particulate filter 19 are provided in the EGR passage 16 on the exhaust gas downstream side of the EGR flow control valve 17 in this order from the exhaust gas upstream side.
The oxidation catalyst 18 is a monolith catalyst in this example, and is constituted by supporting Pt on a honeycomb carrier made of alumina. The particulate filter 19 is a honeycomb filter in this example, and an active metal is carried on the surface of the filter 19 so that it also functions as an oxidation catalyst. Although not shown, the particulate filter 19 has a large number of polygonal passages partitioned by cordierite porous partition walls through which exhaust gas can pass and particulates cannot pass, and adjacent inlets of these polygonal passages. The parts and the outlet part are sealed alternately. The active metal carried on the surface of the filter 19 is Pt in this example, and it is carried directly on the partition walls of the filter 19 or after the partition walls are coated with a slurry containing γ-alumina powder.
The oxidation catalyst 18 and the particulate filter 19 are housed in a single long cylindrical case 21.

The rotation sensor 22 for detecting the rotation speed of the engine 10 and the load sensor 23 for detecting the load of the engine 10 are connected to the control input of the controller 24, and the control output of the controller 24 is connected to the EGR flow control valve 17. To be done. Further, the memory 26 of the controller 24 stores, as a map, an optimum opening degree of the EGR passage 16 by the EGR flow control valve 17 with respect to changes in the rotation speed and the load of the engine 10. The controller 24 controls the EGR flow control valve 17 based on the detection outputs of the rotation sensor 22 and the load sensor 23 to recirculate the exhaust gas to the intake system, so that the heat capacity of the inert gas that occupies most of the exhaust gas is The maximum combustion temperature in the engine 10 is lowered to reduce NOx.
Can be reduced. 27 is the EGR passage 16
Is a muffler provided in the exhaust pipe 14 on the downstream side of the exhaust gas from the branch part.

<Second Embodiment> FIG. 2 shows a second embodiment of the present invention. 2, the same reference numerals as those in FIG. 1 indicate the same parts. In this example, the heat exchanger 41 is provided in the EGR passage 16 on the exhaust gas upstream side of the oxidation catalyst 18, and the refrigerant is supplied to the heat exchanger 41 by the refrigerant supply means 42. Heat exchanger 41
Is a case 41a having both ends connected to the EGR passage 16 and having a diameter larger than that of the EGR passage 16, and a large number of fins (not shown) arranged in the case 41a with a predetermined gap and extending in the exhaust gas flowing direction. ) And a number of tubular bodies (not shown) that pass through these fins and allow the passage of refrigerant.
With. The fin and the tubular body are each S in this example.
It consists of US403 and SUS316. The refrigerant is air in this example.

The refrigerant supply means 42 is provided with a duct 43 connected to the tubular body of the heat exchanger 41, a blower 44 for sending air to the heat exchanger 41 via the duct 43, and the duct 43 provided in the duct 43. An air flow rate control valve 45 capable of adjusting the flow rate of flowing air. The blower 44 has a blower body 44a having rotatable blades (not shown), and a blower motor 44b for driving the blades of the blower body 44a.
Have and. An air cleaner 48 is provided at the suction port of the blower body 44a. The air flow rate control valve 45 has substantially the same structure as the EGR flow rate control valve 17, and has a valve body 45a for opening and closing the duct 43 and a predetermined angle of the valve body 45a, that is, the duct 43 has a predetermined opening degree. And a drive unit 45b configured by a stepping motor or the like that is driven.

The EGR flow control valve 17 is provided with an oxidation catalyst 18
And the EGR passage 16 between the heat exchanger 41 and the EGR passage 16 between the oxidation catalyst 18 and the EGR flow control valve 17.
A temperature sensor 49 for detecting the temperature of the exhaust gas flowing through the EGR passage 16 is inserted in the. The control input of the controller 24 is connected to the respective detection outputs of the temperature sensor 49, the rotation sensor 22 and the load sensor 23, and the control output of the controller 24 is a blower 44, an air flow control valve 45 and an EGR.
It is connected to the flow control valve 17. By the way, it is known that when the exhaust gas temperature at the inlet of the oxidation catalyst 18 exceeds 400 ° C., SO _{2 in} the exhaust gas is oxidized by the oxidation catalyst 18 and the production of sulfate rapidly increases. This sulfate counts as a particulate,
The filter 19 has a size that can hardly be collected. Therefore, the controller 24 is configured to control the blower 44 and the air flow rate control valve 45 so that the temperature of the exhaust gas flowing through the EGR passage 16 does not exceed 350 ° C. Except for the above, the configuration is substantially the same as that of the first embodiment.

COMPARATIVE EXAMPLE 1 Although not shown, the oxidation catalyst and the particulate filter of Example 1 were removed from the EGR passage, and the exhaust gas purifying apparatus having only the EGR flow control valve in the EGR passage was used as Comparative Example 1.

<Evaluation test> For each of the exhaust gas purifying apparatuses of Example 1, Example 2 and Comparative Example 1, the engine 1
EGR under the same conditions of 0 rotation speed and load
The amount (g / hour) of particulates in the exhaust gas recirculated from the passage 16 to the intake pipe 12 was measured.

The results of this test are shown in FIG. As is clear from FIG. 3, in Comparative Example 1, the amount of particulates was 5.
While it was 0 g / hour, in Example 1, the amount of particulates was significantly reduced to 1.0 g / hour. This is because the EGR flow rate control valve 17 is opened and exhaust gas is introduced into the oxidation catalyst 18, and SOF (Soluble Organic) which is unburned fuel and unburned lubricating oil among the particulates in this exhaust gas.
This is because the Fracion) is oxidized by the oxidation catalyst 18 and soot among the particulates in the exhaust gas introduced into the particulate filter 19 is collected. As a result, the exhaust gas containing almost no particulates is circulated to the intake pipe 12, and the durability of the engine 10 can be improved. Further, the soot accumulated on the filter 19 is oxidized by Pt carried on the filter 19, so
Does not clog.

In Example 2, the amount of particulates was 0.
It was 3 g / hour, which was further reduced from Example 1. This is because the temperature of the exhaust gas introduced into the oxidation catalyst 18 is 3 by the heat exchanger 41.
This is because the oxidation catalyst 18 does not generate sulfate because the temperature is controlled to 50 ° C. or lower. Further, the soot deposited on the filter 19 is carried on the filter 19 and is oxidized by Pt which exhibits catalytic activity even at a low temperature of 350 ° C. or less, so that the filter 19 is not clogged.

<Embodiment 3> FIGS. 4 and 5 show Embodiment 3 of the present invention. 4, the same reference numerals as those in FIG. 1 indicate the same parts. In this example, E on the exhaust gas upstream side of the oxidation catalyst 18
The GR passage 66 is formed by bending into a crank shape, and
An EGR flow rate control valve 67 is provided on the crank portion 66 a of the GR passage 66. As shown in detail in FIG. 5, the control valve 67 has a ring-shaped valve seat 67a fixed to the inner peripheral surface of the crank-shaped portion 66a of the EGR passage 66, and is separated from the valve seat 67a or the valve seat 67a. And a valve body 67b that opens and closes the EGR passage 66 by abutting against the valve body 6b.
7b, a drive unit 67c configured by a linear solenoid or the like that drives the EGR passage 66 to reciprocate in the longitudinal direction at the center of the crank-shaped portion 66a so that the EGR passage 66 has a predetermined opening degree.

The peripheral surface of the crank-shaped portion 66a of the EGR passage 66 is covered with a jacket 61a.
A space 61b through which the refrigerant 68 can pass is formed between a and the EGR passage 66. The heat exchanger 61 is composed of the crank-shaped portion 66a of the EGR passage 66 and the jacket 61a. The refrigerant 68 is supplied to the space 61b of the heat exchanger 61 by the refrigerant supply means 62. The refrigerant 68 is water in this example. Returning to FIG. 4, the coolant supply means 62 is provided in the cooling water pipe 63 connected to the jacket 61 a, the cooling water pump 63 for pumping the water 68 to the space 61 b through the cooling water pipe 63, and the cooling water pipe 63. This cooling water pipe 6
And a cooling water flow rate control valve 65 capable of adjusting the flow rate of the water 68 flowing through the water.

The cooling water pump 64 is a pump which is driven by the engine 10 and circulates the engine cooling water through a main pipe 64a to a radiator and an engine cooling section (not shown). One end of the cooling water pipe 63 is connected to the main pipe 64a on the discharge port side of the pump 64, and the other end is connected to the radiator.
The cooling water flow control valve 65 includes a needle valve (not shown) that opens and closes the cooling water pipe 63, and a stepping motor that drives the needle valve to a predetermined angle, that is, the cooling water pipe 63 to a predetermined opening degree. Drive section 65a.

The temperature sensor 49 for detecting the temperature of the exhaust gas flowing through the EGR passage 66 includes the oxidation catalyst 18 and the heat exchanger 6.
1 is inserted into the EGR passage 66. Controller 24
The detection outputs of the temperature sensor 49, the rotation sensor 22 and the load sensor 23 are connected to the control input of the controller 2
The control output of No. 4 is connected to the cooling water flow rate control valve 65 and the EGR flow rate control valve 67. Also, the controller 24 is an EG
The cooling water flow rate control valve 65 is controlled so that the temperature of the exhaust gas flowing through the R passage 66 does not exceed 350 ° C. Except for the above, the configuration is substantially the same as that of the first embodiment. The operation of the exhaust gas purifying apparatus configured as described above is substantially the same as that of the above-described second embodiment, and thus the repeated description will be omitted.

<Fourth Embodiment> FIG. 6 shows a fourth embodiment of the present invention. 6, the same reference numerals as those in FIG. 4 denote the same parts. In this example, the EGR flow control valve 67 is configured substantially the same as the EGR flow control valve of the third embodiment, and the valve seat 67a and the valve body 67b are configured.
And a drive unit 67c. Also, the EGR flow control valve 67
And the heat exchanger 41 provided in the EGR passage 66 between the oxidation catalyst 18 and the heat exchanger 41 of the second embodiment, except that the refrigerant passing through the tubular body (not shown) is water. The case 41a has a large number of fins (not shown) housed in the case 41a, and a large number of tubular bodies (not shown) penetrated by the large number of fins. Heat exchanger 4
The refrigerant supply means 62 for supplying water to the tubular body of No. 1 is the third embodiment.
The refrigerant supply means is substantially the same as the refrigerant supply means. EGR passage 66
The temperature sensor 49 for detecting the temperature of the exhaust gas flowing through is inserted in the EGR passage 66 between the oxidation catalyst 1 and the heat exchanger 41. Except for the above, the configuration is substantially the same as that of the third embodiment. The operation of the exhaust gas purifying apparatus configured as described above is substantially the same as that of the above-described third embodiment, and thus the repeated description will be omitted.

<Fifth Embodiment> FIG. 7 shows a fifth embodiment of the present invention. 7, the same reference numerals as those in FIGS. 1 and 2 denote the same parts. In this example, the EGR passage 16 on the exhaust gas downstream side of the particulate filter 19 is provided with a heat exchanger 71 and a refrigerant supply means 72 having the same structures as the heat exchanger 41 and the refrigerant supply means 42 of the second embodiment, respectively. A temperature sensor 79 for detecting the temperature of the exhaust gas flowing through the EGR passage 16 on the exhaust gas downstream side of the heat exchanger 71.
Is provided. The detection output of the temperature sensor 79 is connected to the control input of the controller 24 together with the detection outputs of the rotation sensor 22 and the load sensor 23, and the control output of the controller 24 is the EGR flow control valve 17 and the refrigerant supply means 71.
Is connected to the air flow control valve 75 and the blower motor 74b. The blower 74 includes a blower body 74a and a blower motor 7
4b and the air cleaner 7 is provided at the suction port of the blower 74.
8 are provided. Also, the discharge port of the blower 74 and the heat exchanger 7
An air flow rate control valve 75 having a valve body 75a and a drive unit 75b is provided in the duct 73 connecting the one tubular body.
Reference numeral 71a is a case of the heat exchanger 71. Except for the above, the configuration is substantially the same as that of the first embodiment.

The operation of the exhaust gas purifying apparatus thus configured will be described. When the temperature sensor 79 detects that the temperature of the exhaust gas purified by the oxidation catalyst 18 and the particulate filter 19 is 100 ° C. or higher, the controller 24 causes the blower motor 74b of the refrigerant supply means 71 to operate based on the detection output of the temperature sensor 79. Drive the blower 74
At the same time as rotating the blades of the air flow control valve 75, the driving portion 75b of the air flow control valve 75 is driven to set the valve body 75a at a predetermined angle, so that a predetermined amount of air is supplied to the tubular body of the heat exchanger 71 via the duct 73. To supply. As a result, the temperature of the purified exhaust gas becomes less than 100 ° C., and the intake pipe 1 of the engine 10
Since a relatively large amount of exhaust gas is supplied to the engine 2,
The combustion efficiency at 0 does not decrease.

<Sixth Embodiment> FIG. 8 shows a sixth embodiment of the present invention. 8, the same reference numerals as those in FIG. 6 indicate the same parts. In this example, the heat exchanger 41 and the refrigerant supply means 62, which are provided in the EGR passage 66 on the exhaust gas downstream side of the particulate filter 19 and the EGR passage 66 on the exhaust gas upstream side of the oxidation catalyst 18, have the same structure. 81 and a refrigerant supply means 82, and a temperature sensor 79 for detecting the temperature of the exhaust gas flowing through the EGR passage 66 is provided in the EGR passage 66 on the exhaust gas downstream side of the heat exchanger 81. To the tubular body (not shown) of the heat exchanger 81, a cooling water pipe 83 branched from a main pipe 64a that connects a cooling water pump 64, a radiator (not shown) and an engine cooling unit (not shown) is connected. A cooling water flow control valve 85 is provided in the middle of the cooling water pipe 83. The detection output of the temperature sensor 79 is connected to the control input of the controller 24 together with the detection outputs of the temperature sensor 49, the rotation sensor 22 and the load sensor 23, and the control output of the controller 24 is the EGR flow control valve 67 and the refrigerant supply means 62. Cooling water flow control valve 65
And the cooling water flow rate control valve 85 of the refrigerant supply means 82. 81a is a case of the heat exchanger 81, and 85a
Is a drive unit of the cooling water flow rate control valve 85. Except for the above, the configuration is substantially the same as that of the fourth embodiment.

The operation of the exhaust gas purifying apparatus configured as described above will be described. Since the temperature of the exhaust gas introduced into the oxidation catalyst 18 does not exceed 350 ° C., the production of sulfate in the oxidation catalyst 18 is reduced. The temperature of the exhaust gas discharged from the particulate filter 19 is 200 ° C to 2 ° C.
Although the temperature is 50 ° C., the exhaust gas is cooled by the heat exchanger 81 to less than 100 ° C., so the combustion efficiency in the engine 10 does not decrease.

<Seventh Embodiment> FIG. 9 shows a seventh embodiment of the present invention. 9, the same reference numerals as those in FIG. 1 indicate the same parts. In this example, the exhaust pipe 14 is provided with an oxidation catalyst 18 and a particulate filter 19 in order from the exhaust gas upstream side.
The GR passage 16 has substantially the same configuration as that of the first embodiment except that the GR passage 16 branches from the exhaust pipe 14 on the exhaust gas downstream side of the particulate filter 19. The operation of the exhaust gas purifying apparatus configured as described above is substantially the same as that of the first embodiment, and thus the repeated description will be omitted.

<Embodiment 8> FIG. 10 shows an embodiment 8 of the present invention. 8, the same reference numerals as those in FIGS. 7 and 9 denote the same parts. In this example, the EGR passage 16 is provided with a heat exchanger 71 and a refrigerant supply means 72 having the same structures as the heat exchanger 71 and the refrigerant supply means 72 of the fifth embodiment, respectively, and the exhaust gas downstream side of the heat exchanger 71. E in the EGR passage 16
A temperature sensor 79 is provided for detecting the temperature of the exhaust gas flowing through the GR passage 16. Except for the above, the configuration is the same as that of the seventh embodiment. The operation of the exhaust gas purifying apparatus configured as described above is substantially the same as that of the fifth embodiment, and thus the repeated description will be omitted.

Although the EGR passage is joined to the intake pipe in the first to eighth embodiments, it may be joined to the intake manifold. Further, in Examples 1 to 8 above, a monolith catalyst in which Pt is supported on a honeycomb carrier made of alumina was used as the oxidation catalyst, but as the honeycomb carrier, cordierite, virillia, mullite, zirconia, silicon nitride, ceramics such as silicon carbide, etc. May be used, and a pellet catalyst may be used instead of the monolith catalyst. Further, instead of Pt, an active metal such as Pd, Ir, Rh, Co, Cu, Ni, Cr may be supported on the honeycomb carrier.

In addition, in the above-mentioned Examples 1 to 8, as the particulate filter, a honeycomb filter having a large number of polygonal passages partitioned by cordierite porous partition walls and supporting Pt on the partition walls was mentioned. If a porous partition wall through which exhaust gas can pass and particulates cannot pass can be formed, a filter may be formed of ceramics such as alumina, beryllia, mullite, zirconia, silicon nitride, or silicon carbide. Without Pd,
You may carry active metals, such as Ir, Rh, Co, Cu, Ni, and Cr. Further, in the above-mentioned Embodiments 3, 4 and 6, the pump that is driven by the engine as the cooling water pump and circulates the engine cooling water to the radiator and the engine cooling part is mentioned, but the present invention is not limited to this, and the heat exchanger of the present invention can be A dedicated pump for supplying water as a refrigerant may be used. In this case, the controller controls the pump in addition to the cooling water flow control valve. Furthermore, the numerical values such as the temperature of the exhaust gas given in the above embodiment are examples, and the numerical values are not limited to these numerical values.

[0033]

As described above, according to the present invention, the EGR passage branched from the exhaust pipe and joined to the intake pipe or the intake manifold is provided with the oxidation catalyst and the particulate filter in order from the exhaust gas upstream side. Since the particulate filter is configured to support the active metal so that the particulate filter also functions as an oxidation catalyst, first, the oxidation catalyst is an SOF that is a fuel unburned component or a lubricating oil unburned component of the particulates in the exhaust gas. Is oxidized, and then the soot among the particulates in the exhaust gas is collected. As a result, it is possible to significantly reduce the particulates in the exhaust gas which are circulated to the intake pipe or the intake manifold. Further, in the present invention, the soot deposited on the filter is oxidized by Pt carried on the filter, as compared with the conventional EGR device in which the filter must be provided with a heating means in order to incinerate the particulate matter deposited on the filter. Therefore, the filter will not be clogged even if the filter is not provided with a heating means.

Further, a heat exchanger capable of exchanging heat with the exhaust gas flowing through the EGR passage is provided in the EGR passage on the exhaust gas upstream side of the oxidation catalyst, and the refrigerant supply means for supplying the refrigerant to the heat exchanger is arranged to remove the exhaust gas flowing through the EGR passage. If the temperature is lowered and the controller is configured to control the refrigerant supply means based on the detection output of the temperature sensor that detects the temperature of the exhaust gas flowing through the EGR passage, the temperature of the exhaust gas flowing into the oxidation catalyst is controlled to a predetermined value or less. Therefore, sulfate is not generated in the oxidation catalyst. As a result, it is possible to further reduce the particulate matter in the exhaust gas that is recirculated from the EGR passage to the intake pipe or the intake manifold. Further, a heat exchanger is provided in the EGR passage on the exhaust gas downstream side of the particulate filter, the refrigerant supply means supplies the refrigerant to the heat exchanger to lower the temperature of the exhaust gas flowing through the EGR passage, and the controller causes the exhaust gas to flow from the particulate filter. If the refrigerant supply means is configured to be controlled based on the output detected by the temperature sensor provided in the EGR passage on the downstream side, the exhaust gas supplied to the engine can be kept below a predetermined temperature. It does not reduce the combustion efficiency.

Further, the exhaust pipe is provided with an oxidation catalyst and a particulate filter in this order from the exhaust gas upstream side, and the particulate filter carries active metal so that the particulate filter also functions as an oxidation catalyst.
Even if the GR passage is configured to branch from the exhaust pipe on the exhaust gas downstream side of the particulate filter, a heat exchanger is further provided in the EGR passage of the exhaust gas purifying apparatus, and the refrigerant supply means supplies the refrigerant to the heat exchanger. Then, the temperature of the exhaust gas flowing through the EGR passage may be lowered, and the controller may control the refrigerant supply means based on the detection output of the temperature sensor provided in the EGR passage on the exhaust gas downstream side of the particulate filter. The same effects as described above can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an exhaust gas purifying apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 3 is a diagram showing the amount of particulates supplied to the intake pipes of Comparative Example 1, Example 1 and Example 2.

FIG. 4 is a configuration diagram corresponding to FIG. 1 showing a third embodiment of the present invention.

5 is an enlarged cross-sectional view of a portion A of FIG.

FIG. 6 is a configuration diagram corresponding to FIG. 1 showing a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram corresponding to FIG. 1 showing a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram corresponding to FIG. 6 showing a sixth embodiment of the present invention.

FIG. 9 is a configuration diagram corresponding to FIG. 1, showing a seventh embodiment of the present invention.

FIG. 10 is a configuration diagram corresponding to FIG. 9 showing an eighth embodiment of the present invention.

[Explanation of symbols]

 10 Diesel engine 11 Intake manifold 12 Intake pipe 13 Exhaust manifold 14 Exhaust pipe 16,66 EGR passage 17,67 EGR flow control valve 18 Oxidation catalyst 19 Particulate filter 22 Rotation sensor 23 Load sensor 24 Controller 41, 61, 71, 81 Heat Exchanger 42, 62, 72, 82 Refrigerant supply means 43, 73 Duct 44, 74 Blower 45, 75 Air flow control valve 49, 79 Temperature sensor 63, 83 Cooling water pipe 64 Cooling water pump 65, 85 Cooling water flow control valve 68 Water (refrigerant)

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[Procedure amendment]

[Submission date] September 14, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

<Second Embodiment> FIG. 2 shows a second embodiment of the present invention. 2, the same reference numerals as those in FIG. 1 indicate the same parts. In this example, the heat exchanger 41 is provided in the EGR passage 16 on the exhaust gas upstream side of the oxidation catalyst 18, and the refrigerant is supplied to the heat exchanger 41 by the refrigerant supply means 42. Heat exchanger 41
Is a case 41a having both ends connected to the EGR passage 16 and having a diameter larger than that of the EGR passage 16, and a large number of fins (not shown) arranged in the case 41a with a predetermined gap and extending in the exhaust gas flowing direction. ) And a number of tubular bodies (not shown) that pass through these fins and allow the passage of refrigerant.
With. The fin and the tubular body are each S in this example.
It consists of US 304 and SUS 316. The refrigerant is air in this example.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display area F01N 3/02 301 F01N 3/02 301E 3/24 ZAB 3/24 ZABE ZABS 5/02 5/02 GB F01P 7/16 504 F01P 7/16 504C 505 505B

Claims (9)

[Claims] 1. An intake pipe (12) connected to an intake manifold (11) of an engine (10) for supplying air to the engine (10).
And an exhaust pipe (14) which is connected to the exhaust manifold (13) of the engine (10) and discharges the exhaust gas of the engine (10) to the atmosphere.
And an EGR passage (16, 66) branching from the exhaust pipe (14) and joining the intake pipe (12) or the intake manifold (11).
An EGR flow control valve (17, 67) capable of adjusting the flow rate of exhaust gas recirculated from the EGR passage (16, 66) to the intake pipe (12) or the intake manifold (11); and the engine (10 )
A rotation sensor (22) for detecting the rotation speed of the engine,
A load sensor (23) that detects the load of (10), and a controller (24) that controls the EGR flow control valve (17) based on the detection outputs of the rotation sensor (22) and the load sensor (23).
In the exhaust gas purifying apparatus including, an EGR passage (16, 66) is provided with an oxidation catalyst (18) and a particulate filter (19) in order from the exhaust gas upstream side, and the particulate filter (19) is provided with an active metal. An exhaust gas purifying apparatus, characterized in that the particulate filter (19) is carried so that the particulate filter (19) also functions as an oxidation catalyst. 2. Pt, Pd, Ir, Rh, Co, C as the oxidation catalyst (18) on a carrier of alumina, cordierite, beryllia, mullite, zirconia, silicon nitride or silicon carbide.
The exhaust gas purifying apparatus according to claim 1, which is configured to carry an active metal of u, Ni, or Cr. 3. The active metal supported on the particulate filter (19) is Pt, Pd, Ir, Rh, Co, Cu,
The exhaust gas purifying apparatus according to claim 1, which is Ni or Cr. 4. EGR on the exhaust gas upstream side of the oxidation catalyst (18)
A heat exchanger (41, 61) provided in the passage (16, 66) and capable of exchanging heat with the exhaust gas flowing through the EGR passage (16, 66), and a refrigerant (68) in the heat exchanger (41, 61). Supply the above EGR
Refrigerant supply means (42, 62) for lowering the temperature of the exhaust gas flowing through the passages (16, 66), and the EGR passage (1) on the exhaust gas upstream side of the oxidation catalyst (18).
6, 66) and a temperature sensor (49) for detecting the temperature of the exhaust gas flowing through the EGR passages (16, 66), and the controller (24) based on the detection output of the temperature sensor (49). The exhaust gas purification apparatus according to any one of claims 1 to 3, which is configured to control the supply means (42, 62). 5. A heat exchanger (71, 8) provided in an EGR passage (16, 66) on the exhaust gas downstream side of the particulate filter (19) and capable of exchanging heat with the exhaust gas flowing through the EGR passage (16, 66).
1) and a refrigerant is supplied to the heat exchanger (71, 81) to supply the EGR passage.
The refrigerant supply means (72, 82) for lowering the temperature of the exhaust gas flowing through (16, 66), and the EGR passage (16, 66) provided on the exhaust gas downstream side of the particulate filter (19) are provided in the EGR passage ( 16,6
A temperature sensor (79) for detecting the temperature of the exhaust gas flowing through 6), the controller (24) is configured to control the refrigerant supply means (72, 82) based on the detection output of the temperature sensor (79) The exhaust gas purification apparatus according to any one of claims 1 to 4. 6. The refrigerant is air, and the refrigerant supply means (42, 72) connects the duct (43, 73) connected to the heat exchanger (41, 71) and the duct (43, 73). A blower (44,74) for sending the air under pressure to the heat exchanger (41,71) via the duct (43,73) and adjusting the flow rate of the air flowing through the duct (43,73). Possible Air Flow Control Valve (45,75)
And a controller (24) based on the detection output of the temperature sensor (49, 79), the blower (44, 74) and the air flow control valve (45, 7).
The exhaust gas purifying apparatus according to claim 4 or 5, which is configured to control 5). 7. The coolant (68) is water, and the coolant supply means (62, 82) includes cooling water pipes (63, 83) connected to a heat exchanger (61), and the cooling water pipes (63, 83). A cooling water pump (64) for pumping the water (68) to the heat exchanger (61, 81) via (83), and the cooling water pipe (63, 83) provided in the cooling water pipe (63, 83). Cooling water flow control valve that can adjust the flow rate of the water (68) flowing through
(65,85), the controller (24) based on the detection output of the temperature sensor (49,79) the cooling water flow control valve (65,85) or the cooling water flow control valve (65,85) The exhaust gas purifying apparatus according to claim 4 or 5, which is configured to control the cooling water pump (64). 8. An intake pipe (12) connected to an intake manifold (11) of an engine (10) for supplying air to the engine (10).
And an exhaust pipe (14) which is connected to the exhaust manifold (13) of the engine (10) and discharges the exhaust gas of the engine (10) to the atmosphere.
And an EGR passage (16) branched from the exhaust pipe (14) and connected to the intake pipe (12) or the intake manifold (11),
An EGR flow control valve (17) provided in the EGR passage (16) and capable of adjusting the flow rate of exhaust gas recirculated to the intake pipe (12) or the intake manifold (11), and a rotation speed of the engine (10). A rotation sensor (22) for detecting the load, a load sensor (23) for detecting the load of the engine (10), and the rotation sensor (22)
And E based on each detection output of the load sensor (23)
In an exhaust gas purifying apparatus including a controller (24) for controlling a GR flow rate control valve (17), an oxidation catalyst (18) and a particulate filter (19) are provided in the exhaust pipe (14) in order from an exhaust gas upstream side. The particulate filter (19) is configured such that an active metal is carried on the particulate filter (19) so that the particulate filter (19) also functions as an oxidation catalyst, and the EGR passage (16) includes the particulate filter (1).
An exhaust gas purifying device characterized in that it is branched from the exhaust pipe (14) on the exhaust gas downstream side of 9). 9. A heat exchanger (71) provided in an EGR passage (16) and capable of exchanging heat with exhaust gas flowing through the EGR passage (16), and a refrigerant is supplied to the heat exchanger (71) to supply the EGR. Aisle (16)
Refrigerant supply means for lowering the temperature of the exhaust gas flowing through (72)
And the EGR passages (16, 66) provided in the EGR passages (16, 66).
And a temperature sensor (79) for detecting the temperature of the exhaust gas flowing through 6), the controller (24) is configured to control the refrigerant supply means (72) based on the detection output of the temperature sensor (79). The exhaust gas purifying apparatus according to claim 8.