JP2000204925A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a size of an exhaust emission control device of internal combustion engine and facilitate mounting of the device to a small vehicle. SOLUTION: Two particulate filters 10, 10 are stored in a case 2 which can be divided into an upstream case part 4 and a downstream case part 5. The upstream case part 4 are formed dividedly so as to store separately each of the filters 10, 10, and the downstream case part 5 is formed to store both filters 10, 10. Filter flanges 11 arranged at the filters 10 and case flanges 6, 7 are coupled to each other such that the filter flanges 11 are held by the case flanges 6, 7 provided in both case parts 4, 5, and each of case flange side parts 42 of the upstream case part 4 is formed to have a diameter smaller than that of each of body parts 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine which collects fine particles (particulates) contained in the exhaust gas of the internal combustion engine and purifies the exhaust gas.

[0002]

2. Description of the Related Art Generally, exhaust gas discharged from a diesel engine contains particulates (exhaust particulates) mainly composed of carbon. For this reason, in a vehicle equipped with a diesel engine, a ceramic columnar diesel particulate filter [hereinafter simply referred to as a filter or DPF (= DPF) is provided in an exhaust pipe (exhaust passage).
Diesel Particurate Filter), which collects particulates in exhaust gas.
Emissions of particulates are reduced.

[0003] When particulates accumulate in the filter, the particulates are clogged in the filter and the air permeability is impaired. For this reason, it is necessary to periodically remove the particulates in the filter to regenerate the filter. In order to regenerate the filter, a technique of burning the particulates in the filter is generally well known. However, when regenerating such a filter, the particulates cannot be collected. Thus, conventionally, a pair of (two) filters are provided in parallel, and when one of the filters is regenerated, the other filter is used to collect the particulates so that the collection of the particulates can be continued. An exhaust gas purification device has been proposed.

Hereinafter, an example of the configuration of such an exhaust gas purifying apparatus will be described with reference to FIG. 5. A front pipe 101 branched in two directions toward the downstream side in the exhaust gas flow direction is provided on the exhaust passage. Two passages 101 a, branched from the front pipe 101.
Cases 102a and 102b are interposed in 101b, respectively. Filters (not shown) are stored in the cases 102a and 102b, respectively, and particulates are collected by these filters.

A tail pipe 103 having two passages 103a and 103b is connected to the rear (downstream side) of each of the cases 102a and 102b. Exhaust gas is discharged to the atmosphere via the tail pipe 103. You. Each of these cases 102a and 102b has
It is configured to be divisible. That is, as illustrated, the cases 102a and 102b are
4 and a downstream case portion 105, and flange portions 106 and 107 formed on the outer peripheral edge of the openings (connection portions) of these case portions 104 and 105 are provided with bolts 108.
, The case portions 104 and 105 are integrally connected.

By the way, on the respective passages 101a, 101b of the front pipe 101, on-off valves 109a, 109b are provided as shown in the figure. Each of these open / close valves 109a and 109b is an on / off valve that operates based on a control signal from control means (control) (not shown), and is switched to either a fully closed state or a fully open state. That is, the on-off valves 109a, 109
b to control the operating state of the passage 101a, 1
01b is configured to be selectively switched to a communication state or a cutoff state.

The above-mentioned passage 101a and passage 101b
A passage 110 is provided between. Here, one end of the passage 110 is connected to the on-off valve 109a and the case 102.
a, and the other end is on-off valve 109
b and the case 102b. Further, a control valve 111 is interposed in the passage 110. Here, the control valve 111 is configured as a control valve whose opening can be adjusted based on a control signal from a controller.

Then, one of the filters in each of the cases 102a and 102b (for example, the case
When particulates accumulate on the filter (a), the filter is regenerated as follows.
First, the on-off valve 109a is fully closed and the on-off valve 109b is fully open to shut off the flow of exhaust gas into the case 102a. In this case, the front pipe 10
1, the exhaust gas flows into the entire passage 101b, and the particulates contained in the exhaust gas are collected by the other filter (for example, the filter in the case 102b).

In this state, the filter in the case 102a is heated by an electric heater or the like to burn carbon, which is a main component of the particulates. In this case, when the carbon starts burning, the operation of the electric heater is stopped. Thereafter, the combustion spreads due to the self-ignition of carbon, and the carbon is removed. Although the electric heater is not shown,
Usually, it is arranged in the case 102a, 102b on the upstream side of the filter.

At this time, the control valve 111 is controlled so as to have a predetermined opening degree, and oxygen necessary for particulate combustion is supplied from the passage 110 side. When the filter in the case 102b is to be regenerated, on the contrary, the on-off valve 109a is fully opened and the on-off valve 109b is fully closed, and the particulate matter accumulated in the filter in the case 102b is conversely described. Burn it.

[0011]

However, the exhaust gas purifying apparatus as shown in FIG. 5 has a problem that the whole system becomes large and it is difficult to mount it on a relatively small vehicle. That is, in this device, the two cases 102a and 102b are arranged in parallel and the front pipe 101 and the tail pipe 103 are connected to each other, so that the width dimension W and the length dimension L are large, and therefore, the vehicle is not used. There is a problem that the mountability of the device is impaired.

Incidentally, Japanese Patent Publication No. 3-80962 discloses a technique in which two filters are arranged in parallel in a common case. And with this technology,
A case that can be divided into an upstream case part and a downstream case part is used, and a partition wall (partition plate) that divides the inside of the case into an entrance side and an exit side is interposed in a divided opening of one case part. Filters are respectively attached to a pair of filter mounting openings formed in the partition wall, and the filters are housed in a common case.

[0013] The mounting structure of the filter is as follows.
A filter flange is mounted on the outer periphery of each filter, and each part of the filter flange is fastened to an opening edge for mounting each filter with a bolt other than a case connecting bolt, and each filter is fixed to a partition wall. Structure is used. However, in the technique of this publication, since the case connecting bolt and the filter mounting bolt are separate bolts, a space for disposing the filter fixing bolt between the peripheral wall of the case and the filter is required. However, there is a problem that the size cannot be sufficiently reduced. There is also a problem that many fastening points are required and many bolts are required.

The present invention has been made in view of the above problems, and provides an exhaust gas purifying apparatus for an internal combustion engine, which can further reduce the size of the entire system and can be easily mounted on a small vehicle. The purpose is to:

[0015]

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, a plurality of particulate filters provided in parallel with each other in an exhaust path of the internal combustion engine includes an upstream case along an exhaust gas flow direction. It is housed in a case that can be divided into a part and a downstream case part. Further, the upstream case portion is individually formed so as to house each particulate filter, and the downstream case portion is formed as a common case portion which houses both the particulate filters. Then, by fastening the flanges so that the filter flange provided on the particulate filter is sandwiched by the case flange provided on the connection portion between the upstream case portion and the downstream case portion, The particulate filter is fixed to the case.

By making the downstream case part common, that is, one unit, the size of the exhaust gas purification device can be further reduced. That is, only the downstream case portion is shared, and the filter flange is sandwiched between the two case flanges of the upstream case portion and the downstream case portion, so that the filter flange is attached and fixed using bolts or the like that joins the two case flanges. This eliminates the need for bolts and the like dedicated to fastening the filter flange, which were conventionally required. Further, the space required only for fastening the filter flange can be eliminated. Furthermore, by forming the case flange side portion of the upstream case portion smaller in diameter than the main body portion of the upstream case portion, that is, by narrowing the case flange portion of the upstream case portion, each upstream case portion is formed. The parts can be arranged close to each other, and the size can be further reduced.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an overall structure of an exhaust gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention; FIG. It is typical sectional drawing, (a) is a figure which shows the flange shape at the time of forming the flange of an upstream case part integrally, (b) is the flange at the time of forming the flange of an upstream case part individually. FIG. 3 is a schematic cross-sectional view showing a configuration of a main part thereof, in which (a) is a cross-sectional view in which a downstream end of an upstream case is narrowed down,
FIG. 4B is a cross-sectional view in the case of forming without being narrowed down, and FIG. 4 is a view showing the entire configuration thereof, and is a view showing the size of the conventional apparatus in comparison.

The exhaust gas purifying apparatus for an internal combustion engine according to the present embodiment comprises:
It is provided on an exhaust path (exhaust passage) of an internal combustion engine (engine), particularly a vehicle equipped with a diesel engine, and is provided with a front pipe 1, a case 2, and a tail pipe 3 from the upstream side as shown in FIG. I have. The front pipe 1 branches into two passages 1a and 1b toward the downstream side in the exhaust gas flow direction.
The downstream end of 1 b is connected to the case 2.

In the case 2, two particulate filters (filters) 10, 10 are arranged in parallel so that the particulates in the exhaust gas are collected by the filters 10, 10. Has become. Exhaust gas passing through the filters 10 and 10 is discharged through the tail pipe 3. The case 2 includes an upstream case portion (hereinafter, referred to as a front case) 4 and a downstream case portion (hereinafter, referred to as a rear case) 5.
And can be divided into two cases.

Focusing on the front case 4 of the two cases 4 and 5, the front case 4
Are formed as separate cases 4a, 4b for accommodating the two filters 10, 10, respectively. As shown in FIG. 1, the upstream halves of the filters 10, 10 are accommodated in the front cases 4a, 4b, respectively. In the following, the front case 4
In the case where a and 4b are not particularly distinguished or when the two front cases 4a and 4b are referred to as one functional unit, the description will be given with the reference numeral 4 attached to the end.

As shown in FIGS. 1 and 3A, each of the front cases 4a and 4b is formed in a cylindrical shape, and the diameter of the downstream portion (case flange side portion) 42 is changed to the upstream portion ( It is formed to be narrower than the main body portion 41. That is, the front cases 4a and 4b are
The diameter of the downstream portion 42 is smaller than that of the downstream portion. In addition, it is preferable to set the inside diameter of the above-mentioned downstream portion 42 as small as possible within a range in which the filter 10 can be stored.

The rear case 5 is provided with each of the filters 10,
10 are formed as a common case in which both can be stored. As shown in FIG. 1, the rear half of each of the filters 10, 10 is housed in the rear case 5. As shown in FIG. 1, a rear pipe 3 is connected to a downstream end of the rear case 5, and the exhaust gas joined in the rear case 5 is discharged through the rear pipe 3. . By the way, the case flanges 6 and 7 are formed at the joints of the above-described front cases 4a and 4b and the rear case 5 (that is, the downstream ends of the front cases 4a and 4b and the upstream end of the rear case 5). And these case flanges 6,7
The front case 4 and the rear case 5 are joined together by fastening them with bolts 8 and the like.
0 and 10 are fixed.

Here, the case flange 6 provided on the front case 4 side is a single plate-like flange as shown in FIG. 2A, and is formed in an oval shape as shown in the figure. I have. The case flange 6 has holes 6a, 6a through which outer peripheral edges of the front cases 4a, 4b can be inserted.
The front case 4 is formed by fixing the front cases 4a and 4b to the holes 6a and 6b by welding or the like.

On the other hand, the case flange 7 is formed in the same shape as the case flange 6 (see FIG. 2A), and is fixed to the rear case 5 at the opening edge of the rear case 5 by welding or the like. I have. As shown in FIG. 3A, each filter 10 is formed with a flange-shaped filter flange 11. This filter flange 11
It is provided on the outer peripheral side of the filter 10 and is fixed to the filter 10.

The case flanges 6 and 7 are fastened by bolts 8 and the like so as to sandwich the filter flange 11, whereby the filter 10 is attached to the case 2 and the front case 4 and the rear case 5 Is to be joined.

A control valve 9 is provided in each passage 1a, 1b.
a, 9b are provided. These control valves 9a, 9b
Is configured as a multi-stage valve whose opening can be adjusted in a plurality of stages from fully open to fully closed.
The operation is independently controlled based on a control signal from a CU (control means). By providing such control valves (multistage valves) 9a and 9b, the oxygen supply passage and the oxygen supply control valve (both shown by reference numerals 110 and 111 in FIG. 5) which are conventionally required are not required. It becomes.

Since the exhaust gas purifying apparatus for an internal combustion engine according to one embodiment of the present invention is configured as described above, for example, when the filter 10 on the side of the passage 1a is regenerated, the control valve 9b is controlled to be fully open. At the same time, the control valve 9a is controlled to have a predetermined opening. Thereby, most of the exhaust gas flows from the passage 1b into the filter 10 in the front case 4b, and the particulates are collected by the filter 10.

On the other hand, the filter 1 in the front case 4a
Numeral 0 is heated by an electric heater (not shown), and carbon, which is a main component of particulates deposited in the filter 10, burns. In this case, when the carbon in the filter 10 starts burning, the operation of the electric heater is stopped, and thereafter, the combustion spreads throughout the filter 10 due to the self-ignition of the carbon. At this time, oxygen required for combustion is supplied to the passage 1a and the front case 4a via the control valve 9a.

The filter 1 in the front case 4b
At the time of regeneration of 0, contrary to the above, the control valve 9a is controlled to be fully opened and the control valve 9b is controlled to have a predetermined opening degree. Otherwise, the filter 10 is regenerated in the same manner as described above. According to the exhaust gas purifying apparatus for an internal combustion engine of the present embodiment, by forming the case flanges 6 of the front cases 4 integrally, the case flanges 6 are formed in the width direction rather than formed for each of the cases 4a and 4b. Dimensions can be reduced. That is, FIG.
As shown in FIG.
In the case where the front case 4a and the front case 4b are formed with each other, the center-to-center dimension A becomes larger than necessary by the width of the flange 6 because the flanges 6 are present between the front cases 4a and 4b. By integrally forming the case flange 6 of the front case 4 with the front case 4,
a, 4b can be arranged close to each other, and the center-to-center dimension a
Can be made smaller than the above-described dimension A.

Further, in the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, the front case 4 is individually formed so as to house each filter 10, and the rear case 5 is made common (ie, one unit). Thus, the size of the entire apparatus can be further reduced. That is, by separately forming the front case 4, the front case 4 is attached to the case flange 6 over the entire circumference of each of the front cases 4 a and 4 b (or the entire circumference of each of the filters 10 and 10).
Bolts 8 and the like for joining the rear case 5 and the rear case 5 can be provided. When joining the cases 4 and 5, the filters 10 and 10 are connected to the case 10 using the joining bolts 8 and the like. 2 can be fixed. Thus, bolts and the like dedicated to mounting the filters 10, 10 can be eliminated, and the weight can be reduced. Further, the space required only for fastening the filter flanges 11 and 11 to the case 2 can be eliminated, and the size can be reduced.

Note that the prior art (for example, Japanese Patent Publication No. 3-80)
962), when the front case 4 is formed in common, the bolts 8 for fixing the flange can be arranged over the entire circumference of the front case 4, but each filter 10, 10 Cannot be provided over the entire circumference of the filter, so that the filter 10 cannot be attached to the case 2 with the common bolt 8, and the bolts for fixing the filters 10 and 10 to the case 2 are not provided. And the like, and a space for fixing the filter 10 is required. On the other hand, in the present apparatus, such a problem is solved by forming the front case 4 individually.

Further, the downstream parts (case flange side parts) 42 of the front cases 4a, 4b are narrowed (ie, formed to have a smaller diameter) than the upstream parts (main body parts), so that the two front cases 4a, 4b are formed. Can be arranged closer to each other, and the width of the device can be reduced. Hereinafter, the reason will be briefly described. An electric heater (not shown) for regenerating a filter is provided in the front cases 4a and 4b. Generally, the electric heater is formed to have a larger diameter than the filter 10 so as to satisfy the required performance and the like. The inner diameter D of each of 4a and 4b is sufficiently larger than the outer diameter of the filter 10 (see FIG. 3B). Therefore, the front case 4
When a and 4b are formed in a cylindrical shape having a constant inner diameter D, the downstream portion of the front cases 4a and 4b is disposed between the filter 10 and the front cases 4a and 4b as shown in FIG.
A space (dead space) as shown in FIG.

On the other hand, as shown in FIG. 3 (b), bolts 8 and the like are arranged on the case flange 6 side portion between the two front cases 4a and 4b, and predetermined dimensions are required for performing a fastening operation. B is required, but if the predetermined dimension B can be reduced, the overall width of the apparatus can be further reduced. Therefore, in the present embodiment, as shown in FIG.
By narrowing the downstream portion of b to a level slightly larger than the outer diameter of the filter 10, the distance between the two front cases 4a and 4b ( The dimension b) is set smaller than the dimension B.

Further, for the same reason as described above, FIG.
As shown in (b), a predetermined dimension C is also required between the outer peripheral ends of the case flanges 6, 7 and the front cases 4a, 4b, but the downstream parts of the front cases 4a, 4b are also narrowed. In the vicinity of the position where the bolt 8 is provided, the predetermined dimension C is maintained while the case flanges 6 and 7 are secured.
Of the front case 4a, 4b can be made smaller than the above-described dimension C.

Therefore, by narrowing the downstream portions of the front cases 4a, 4b,
b is formed in a cylindrical shape having a constant inner diameter D [FIG.
Compared with (b)], the overall width of the device can be reduced. Further, in the exhaust gas purifying apparatus for an internal combustion engine according to the present embodiment, since the exhaust gas passing through the two filters 10 and 10 is configured to merge in the rear case 5, the tail pipe 3 is a conventional one (see FIG. Symbol 103 of 5
(See Reference).

As described above, by providing the control valves (multi-stage valves) 9a and 9b whose opening can be adjusted, the oxygen supply passage and the oxygen supply control valve (both shown in FIG. (See reference numerals 110 and 111) are not required, thereby shortening the length dimension and greatly reducing the weight. by the way,
FIG. 4 is a diagram showing a comparison between the exhaust gas purifying apparatus of the present embodiment and a conventional apparatus (having a different configuration but the same configuration as the system in FIG. 5), and a solid line indicates the configuration of the present apparatus. The dotted line indicates the shape of the conventional device. The present apparatus and the conventional apparatus are configured so that the exhaust gas purifying performance is equal.

In the present apparatus, various devices as described above,
That is, by accumulating various effects such as the individual formation of the front cases 4a and 4b, the integral formation of the flanges of the front cases 4a and 4b, the reduction of the downstream diameter of the front cases 4a and 4b, and the commonization of the rear case 5, FIG. As shown in (1), the length and width can be greatly reduced as compared with the conventional one. Further, in addition to such miniaturization, the filter 1 is mounted on a common bolt 8 (see FIGS. 1 to 3).
By fixing 0, the weight can be significantly reduced. In addition, there is an advantage that the cost for manufacturing can be reduced.

The exhaust gas purifying apparatus for an internal combustion engine according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example,
The front case 4 and the case flange 6 do not necessarily have to be fixed by welding, and may be integrally formed from the beginning by another method such as casting. This is rear case 5
The same applies to the case flange 7 and the case flange 7.

Further, the control valves 9a and 9b may be configured as ordinary on-off valves, and a control valve capable of adjusting the opening degree may be provided between the passages 1a and 1b.

[0040]

As described above in detail, according to the exhaust gas purifying apparatus for an internal combustion engine of the present invention, a plurality of particulate filters are formed along the flow direction of the exhaust gas by the upstream case portion and the downstream case portion. The upstream case part is formed individually so as to store each particulate filter, and the downstream case part is used as a common case part that stores both the particulate filters together. The particulate filter is fixed to the case by fastening each flange so that the filter flange formed on the particulate filter is sandwiched between the case flanges provided on the upstream case portion and the downstream case portion, respectively. And, the case flange side portion of the upstream case portion is formed to have a smaller diameter than the main body portion of the upstream case. The simple configuration of that, in addition to the advantage that it is possible to achieve a significant reduction in size and weight reduction of the exhaust purification apparatus also has the advantage that the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of an exhaust gas purification device for an internal combustion engine as one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a configuration of a main part of an exhaust gas purifying apparatus for an internal combustion engine as one embodiment of the present invention, in which (a) shows a case where a flange of an upstream case is integrally formed. FIG. 4B is a diagram illustrating a flange shape, and FIG. 4B is a diagram illustrating a flange shape when flanges of an upstream case portion are individually formed.

FIG. 3 is a schematic cross-sectional view showing a configuration of a main part of an exhaust gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention, in which (a) is formed by narrowing a downstream end of an upstream case portion. FIG. 3B is a cross-sectional view when formed without being narrowed down.

FIG. 4 is a diagram showing an overall configuration of an exhaust gas purification device for an internal combustion engine as one embodiment of the present invention, and is a diagram showing a size comparison with a conventional device.

FIG. 5 is a schematic diagram showing the entire configuration of a conventional exhaust gas purification device.

[Explanation of symbols]

 4, 4a, 4b Upstream case part (front case) 5 Downstream case part (rear case) 6, 7 Case flange 10 Particulate filter (filter) 11 Filter flange 41 Main part of upstream case part 42 Upstream case part Case flange side part of

Claims (1)

[Claims] 1. An exhaust gas purification apparatus for an internal combustion engine in which a plurality of particulate filters are provided in parallel in an exhaust path of the internal combustion engine, wherein each of the particulate filters is an upstream case along an exhaust gas flow direction. And the downstream case part is housed in a case that can be divided into a part and a downstream case part. The upstream case part is individually formed so as to house each of the particulate filters described above. A case flange is formed at a connection part between each of the upstream case parts and the downstream case part, and is formed as a common case part that accommodates both the particulate filters.
A filter flange is formed on the outer periphery of the particulate filter, and the particulate filter is fixed to the case by fastening the flanges so that the filter flange is sandwiched between the case flanges, and An exhaust gas purifying apparatus for an internal combustion engine, wherein the case flange side portion of the upstream case portion has a smaller diameter than the main body portion of the upstream case portion.