JP3858493B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purification apparatus for an internal combustion engine that collects particulates (particulates) contained in the exhaust gas of the internal combustion engine and purifies the exhaust gas.
[0002]
[Prior art]
In general, exhaust gas discharged from a diesel engine contains particulates (exhaust particulates) mainly composed of carbon.
For this reason, an automobile equipped with a diesel engine is provided with a ceramic cylindrical diesel particulate filter (hereinafter simply referred to as a filter or DPF (= Diesel Particurate Filter)) in an exhaust pipe (exhaust passage). In this way, the particulates in the exhaust gas are collected and the emission of particulates to the atmosphere is suppressed.
[0003]
By the way, when particulates accumulate in the filter, the inside of the filter is clogged by the particulates and air permeability is impaired. For this reason, it is necessary to periodically regenerate the filter by removing the particulates in the filter.
In order to regenerate the filter, a method of burning the particulates in the filter is generally well known. However, when such a filter is regenerated, the particulates cannot be collected. Therefore, conventionally, a pair of (two) filters are provided in parallel, and when one of the filters is regenerated, the particulates can be continuously collected by collecting the particulates with the other filter. An exhaust emission control device has been proposed.
[0004]
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. Cases 102a and 102b are interposed in two passages 101a and 101b branched from the front pipe 101, respectively. Further, filters (not shown) are accommodated in the cases 102a and 102b, respectively, and particulates are collected by these filters.
[0005]
Further, a tail pipe 103 having two passages 103a and 103b is connected to the rear (downstream side) of each case 102a and 102b, and the exhaust gas is discharged to the atmosphere through the tail pipe 103.
Further, these cases 102a and 102b are both configured to be divided into two. That is, as shown in the figure, the cases 102a and 102b have an upstream case portion 104 and a downstream case portion 105, and are formed at the outer peripheral edge portions of the openings (connection portions) of these case portions 104 and 105. The case portions 104 and 105 are integrally connected by fastening the flange portions 106 and 107 with the bolts 108.
[0006]
On the other hand, on the passages 101a and 101b of the front pipe 101, on-off valves 109a and 109b are respectively provided as shown in the figure. These on-off valves 109a and 109b are on / off valves that operate based on a control signal from a control means (control) (not shown), and are switched to a fully closed state or a fully open state. In other words, the passages 101a and 101b can be selectively switched between the communication state and the shut-off state by controlling the operating states of the on-off valves 109a and 109b.
[0007]
A passage 110 is provided between the passage 101a and the passage 101b. Here, one end of the passage 110 is connected between the on-off valve 109a and the case 102a, and the other end is connected between the on-off valve 109b 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 degree can be adjusted based on a control signal from a controller.
[0008]
When particulates accumulate on one of the filters in the cases 102a and 102b (for example, the filter in the case 102a), the filter is regenerated as follows.
First, the on-off valve 109a is fully closed and the on-off valve 109b is fully opened to block the inflow of exhaust gas into the case 102a. In this case, exhaust gas in the front pipe 101 flows into the entire passage 101b, and particulates contained in the exhaust gas are collected by the other filter (for example, a filter in the case 102b).
[0009]
In this state, the filter in the case 102a is heated by an electric heater or the like to burn carbon that is the main component of the particulates. In this case, the operation of the electric heater is stopped when the carbon starts to burn. From then on, combustion spreads due to self-ignition of carbon and carbon is removed. Although not shown, the electric heater is usually disposed upstream of the filter in the cases 102a and 102b.
[0010]
At this time, the control valve 111 is controlled to have a predetermined opening, and oxygen necessary for particulate combustion is supplied from the passage 110 side.
When regenerating the filter in the case 102b, contrary to the above, the on-off valve 109a is fully opened and the on-off valve 109b is fully closed, and the particulates accumulated on the filter in the case 102b are removed. It burns.
[0011]
[Problems to be solved by the invention]
However, the exhaust emission control device as shown in FIG. 5 has a problem that the entire system becomes large and is difficult to mount on a relatively small vehicle. That is, in this apparatus, since the two cases 102a and 102b are arranged in parallel, and the front pipe 101 and the tail pipe 103 are connected, the width dimension W and the length dimension L become large, and therefore, to the vehicle. There is a problem of impairing the mountability of.
[0012]
Incidentally, for example, Japanese Patent Publication No. 3-80962 discloses a technique in which two filters are arranged in parallel in a common case. In this technique, a case that can be divided into an upstream case portion and a downstream case portion is used, and a partition wall (partition) that divides the inside of the case into an entrance side and an exit side is formed in a split opening of one case portion. The filter is attached to a pair of openings for mounting the filter formed in the partition wall, and the filters are accommodated in a common case.
[0013]
In addition, the filter mounting structure is such that a filter flange is attached to the outer periphery of each filter, and each part of the filter flange is fastened to the opening edge of each filter with a bolt other than the case joining bolt. A structure in which each filter is fixed to the partition wall is used.
However, in the technique of this publication, the case joining bolt and the filter mounting bolt are separate bolts, so that a space for arranging the filter fixing bolt between the peripheral wall of the case and the filter is necessary. There is a problem that sufficient miniaturization cannot be achieved. There is also a problem that there are many fastening points and a large number of bolts are required.
[0014]
The present invention was devised in view of such problems, and an object of the present invention is to provide an exhaust gas purification apparatus for an internal combustion engine that can further reduce the size of the entire system and can be easily mounted on a small vehicle. And
[0015]
[Means for Solving the Problems]
In the exhaust gas purification apparatus for an internal combustion engine of the present invention, a plurality of particulate filters provided in parallel with each other in the exhaust path of the internal combustion engine are divided into an upstream case portion and a downstream case portion along the flow direction of the exhaust gas. Housed in a possible case. The upstream case portion is individually formed so as to accommodate each particulate filter, and the downstream case portion is formed as a common case portion that accommodates each particulate filter together. And, by fastening the flanges so that the filter flange provided in the particulate filter is sandwiched between the case flanges provided at the connection portions between the upstream case portions and the downstream case portions, The particulate filter is fixed to the case.
[0016]
Further, the exhaust case purification device can be further miniaturized by using the downstream case portion in common, that is, using one unit. That is, only the downstream case portion is made common, and the filter flange is clamped by both the case flanges of the upstream case portion and the downstream case portion, so that the filter flange is attached and fixed using a bolt or the like that joins both case flanges. Therefore, the bolts for exclusive use of fastening the filter flange, which have been conventionally required, can be eliminated. Moreover, the space required only for fastening the filter flange can be eliminated. Furthermore, each upstream case is formed by forming the case flange side portion of the upstream case portion to be smaller in diameter than the main body portion of the upstream case portion, that is, by narrowing the case flange side portion of the upstream case portion. The parts can be arranged close to each other, and further downsizing can be achieved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an exhaust gas purification apparatus for an internal combustion engine as an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration, and FIG. 2 is a schematic cross-sectional view showing the main configuration thereof. (A) is a diagram showing the flange shape when the flange of the upstream case portion is integrally formed, (b) is a diagram showing the flange shape when the flange of the upstream case portion is individually formed, FIG. FIG. 2A is a schematic cross-sectional view showing the configuration of the main part, where FIG. 2A is a cross-sectional view when the downstream case portion is formed by narrowing the downstream end, and FIG. FIG. 4 is a diagram showing the overall configuration, and is a diagram comparing the size with a conventional device.
[0018]
The exhaust gas purification apparatus for an internal combustion engine according to the present embodiment is provided on an exhaust path (exhaust passage) of an internal combustion engine (engine), particularly a vehicle equipped with a diesel engine, and as shown in FIG. A case 2 and a tail pipe 3 are provided. Among these, the front pipe 1 is branched into two passages 1a and 1b toward the downstream side in the exhaust gas flow direction, and the downstream ends of the passages 1a and 1b are connected to the case 2, respectively.
[0019]
Further, in the case 2, two particulate filters (filters) 10 and 10 are arranged in parallel, and the particulates in the exhaust gas are collected by these filters 10 and 10. . Further, the exhaust gas that has passed through the filters 10 and 10 is discharged through the tail pipe 3.
The case 2 is configured to be divided into two case parts, an upstream case part (hereinafter referred to as a front case) 4 and a downstream case part (hereinafter referred to as a rear case) 5.
[0020]
When attention is paid to the front case 4 of the two cases 4 and 5, the front case 4 is formed as individual cases 4a and 4b for accommodating the two filters 10 and 10, respectively. And as shown in FIG. 1, the upstream half part of each filter 10 and 10 is each accommodated in front case 4a, 4b. In the following description, when the front cases 4a and 4b are not particularly distinguished or when the two front cases 4a and 4b are referred to as one functional unit, a reference numeral 4 is attached to the end.
[0021]
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 side portion (case flange side portion) 42 is the upstream side portion (main body portion). It is formed to be narrower than 41. That is, the front cases 4 a and 4 b are formed such that the downstream portion 42 is smaller in diameter than the main body portion 41. In addition, it is preferable to set the internal diameter of the downstream part 42 mentioned above as small as possible in the range in which the filter 10 can be accommodated.
[0022]
The rear case 5 is formed as a common case that can store the filters 10 and 10 together. As shown in FIG. 1, the rear case 5 accommodates the downstream half of the filters 10 and 10. As shown in FIG. 1, a rear pipe 3 is connected to the downstream end of the rear case 5, and exhaust gas merged in the rear case 5 is discharged through the rear pipe 3. .
By the way, case flanges 6 and 7 are formed at the joint portions of the front cases 4a and 4b and the rear case 5 described above (that is, the downstream end portions of the front cases 4a and 4b and the upstream end portion of the rear case 5), respectively. The case flanges 6 and 7 are fastened by bolts 8 or the like, so that the front case 4 and the rear case 5 are joined and the filters 10 and 10 are fixed.
[0023]
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. The case flange 6 is formed with holes 6a and 6b through which the outer peripheral edges of the front cases 4a and 4b can be inserted, and the front cases 4a and 4b are fixed to the holes 6a and 6b by welding or the like. The front case 4 is configured.
[0024]
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.
Further, as shown in FIG. 3A, each filter 10 is formed with a bowl-shaped filter flange 11. The filter flange 11 is provided on the outer peripheral side of the filter 10 and is fixed to the filter 10.
[0025]
The case flanges 6 and 7 are fastened with bolts 8 or 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 are joined. It is supposed to be done.
[0026]
In addition, control valves 9a and 9b are provided in the passages 1a and 1b, respectively. These control valves 9a and 9b are configured as multistage valves whose opening degree can be adjusted in a plurality of stages from fully open to fully closed, and are respectively based on control signals from an ECU (control means) (not shown). The operation is controlled independently.
By providing such control valves (multi-stage valves) 9a and 9b, the oxygen supply passage and the oxygen supply control valve (both refer to reference numerals 110 and 111 in FIG. 5), which are conventionally required, are unnecessary. It becomes.
[0027]
The exhaust gas purification apparatus for an internal combustion engine according to an embodiment of the present invention is configured as described above. For example, when the filter 10 on the passage 1a side is regenerated, the control valve 9b is controlled to be fully opened. The control valve 9a is controlled to have a predetermined opening. Thereby, most of the exhaust gas flows into the filter 10 in the front case 4b from the passage 1b, and the particulates are collected by the filter 10.
[0028]
On the other hand, the filter 10 in the front case 4a is heated by an electric heater (not shown), and the carbon that is the main component of the particulates accumulated 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 carbon. At this time, oxygen necessary for combustion is supplied into the passage 1a and the front case 4a through the control valve 9a.
[0029]
Further, at the time of regeneration of the filter 10 in the front case 4b, the control valve 9a is controlled to be fully opened and the control valve 9b is controlled to have a predetermined opening degree, contrary to the above. The rest of the filter 10 is regenerated in the same manner as described above.
According to the exhaust gas purification apparatus for an internal combustion engine of the present embodiment, the case flange 6 of each front case 4 is integrally formed, so that the case flange 6 is formed in the width direction rather than being formed for each case 4a, 4b. The dimensions can be reduced. That is, as shown in FIG. 2B, when the case flange 6 is formed for each of the cases 4a and 4b, the flange 6 exists between the front cases 4a and 4b. The center-to-center dimension A becomes larger than necessary, but by forming the case flange 6 of the front case 4 integrally as in the present apparatus, the front cases 4a and 4b are arranged close to each other. The center-to-center dimension a can be made smaller than the dimension A.
[0030]
In the exhaust gas purification apparatus for an internal combustion engine of the present invention, the front case 4 is individually formed so as to accommodate the respective filters 10 and the rear case 5 is made common (that is, made into one unit). Further downsizing of the entire apparatus can be achieved.
That is, by forming the front case 4 individually, the front case 4 and the rear case 5 are formed on the case flange 6 over the entire circumference of the front cases 4a and 4b (or the entire circumference of the filters 10 and 10). The bolts 8 and the like can be arranged so that the filters 10 and 10 are fixed to the case 2 by using the joining bolts 8 and the like when the cases 4 and 5 are joined. Can do it. Thereby, the bolts for exclusive use of the attachment of the filters 10 and 10 can be abolished, and the weight can be reduced. Further, the space necessary only for fastening the filter flanges 11 and 11 and the case 2 can be eliminated, and the size can be reduced.
[0031]
When the front case 4 is formed in common as in the prior art (for example, see Japanese Patent Publication No. 3-80962), the flange fixing bolts 8 are arranged over the entire circumference of the front case 4. Although the bolts 8 cannot be provided over the entire circumference of the filters 10 and 10, the filter 10 cannot be attached to the case 2 with the common bolts 8. , 10 to the case 2 are newly required, and a space for fixing the filter 10 is also required. On the other hand, in this apparatus, such a subject is solved by forming the front case 4 separately.
[0032]
Further, by narrowing the downstream portion (case flange side portion) 42 of the front case 4a, 4b more than the upstream portion (main body portion) (that is, forming a smaller diameter), the two front cases 4a, 4b are brought closer to each other. And the width of the apparatus can be reduced.
The reason will be briefly described below. An electric heater (not shown) for regenerating the filter is provided in the front cases 4a and 4b. Generally, the electric heater is formed with a diameter larger than that of the filter 10 so as to satisfy the required performance and the like. The inner diameter D of 4a and 4b is sufficiently larger than the outer diameter of the filter 10 (see FIG. 3B). Therefore, when the front cases 4a 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 shown in FIG. 3B between the filter 10 and the front cases 4a and 4b. A space as shown (dead space) is generated.
[0033]
On the other hand, in the case flange 6 side portion between the two front cases 4a and 4b, as shown in FIG. 3 (b), a predetermined dimension B is required for disposing a bolt 8 or the like or performing a fastening operation. However, if the predetermined dimension B can be reduced, the width of the entire apparatus can be further reduced by that much.
Therefore, in the present embodiment, as shown in FIG. 3A, the downstream side portions of the front cases 4a and 4b are narrowed to a degree slightly larger than the outer diameter of the filter 10, whereby the bolt 8 is disposed. The distance (dimension b) between the two front cases 4a and 4b is set smaller than the dimension B while ensuring the predetermined dimension B in the vicinity.
[0034]
For the same reason as described above, as shown in FIG. 3B, a predetermined dimension C is required between the outer peripheral ends of the case flanges 6 and 7 and the front cases 4a and 4b. By narrowing down the downstream side portions of the front cases 4a and 4b, from the outer peripheral ends of the case flanges 6 and 7 to the outer peripheral surfaces of the front cases 4a and 4b while securing the predetermined dimension C in the vicinity of the position where the bolt 8 is disposed. The dimension c in between can be made smaller than the dimension C described above.
[0035]
Therefore, the width of the entire apparatus can be reduced as compared with the case where the front cases 4a and 4b are formed in a cylindrical shape having a constant inner diameter D by narrowing the downstream portions of the front cases 4a and 4b (FIG. 3B). It can be made smaller.
Further, in the exhaust gas purification apparatus for an internal combustion engine of the present embodiment, the exhaust pipe that has passed through the two filters 10 and 10 is configured to merge in the rear case 5, so that the tail pipe 3 is a conventional one (see FIG. 5 (see reference numeral 103 in FIG. 5).
[0036]
Further, as described above, by providing control valves (multistage valves) 9a and 9b whose opening degree can be adjusted, the oxygen supply passage and the oxygen supply control valve (both denoted by reference numeral 110 in FIG. , 111) is not necessary, and the length can be shortened and the weight can be greatly reduced.
FIG. 4 is a diagram showing a comparison between the exhaust purification apparatus of the present embodiment and a conventional apparatus (having the same configuration as the system of FIG. 5 but having the same configuration), and the solid line shows the shape of the apparatus. A two-dot chain line indicates the shape of a conventional device. The present apparatus and the conventional apparatus are configured to have the same exhaust purification performance.
[0037]
In this apparatus, various devices as described above, that is, 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 in diameter on the downstream side of the front cases 4a and 4b, and the common use of the rear case 5 Due to the accumulation of various effects such as conversion, as shown in FIG. 4, both the length dimension and the width dimension can be greatly reduced as compared with the conventional one. In addition to such downsizing, the weight can be greatly reduced by fixing the filter 10 with a common bolt 8 (see FIGS. 1 to 3). This also has the advantage that the costs associated with manufacturing can be reduced.
[0038]
The exhaust emission control device for an internal combustion engine of the present invention is not limited to the above-described 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 other methods such as casting. The same applies to the rear case 5 and the case flange 7.
[0039]
In addition, the control valves 9a and 9b may be configured as normal on-off valves, and a control valve whose opening degree can be adjusted may be provided between the passages 1a and 1b.
[0040]
【The invention's effect】
As described above in detail, according to the exhaust gas purification apparatus for an internal combustion engine of the present invention, a plurality of particulate filters can be divided into an upstream case portion and a downstream case portion along the flow direction of the exhaust gas. And the upstream case part is individually formed so as to accommodate each particulate filter, and the downstream case part is formed as a common case part that accommodates each particulate filter. The particulate filter is fixed to the case by fastening each flange so that the filter flange formed on the filter is sandwiched between the case flanges provided in the upstream case portion and the downstream case portion, respectively, and the upstream side The case flange side part of the case part is formed with a smaller diameter than the main body part of the upstream case With the configuration, 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 apparatus for an internal combustion engine as an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing a main part configuration of an exhaust gas purification apparatus for an internal combustion engine as an embodiment of the present invention, in which (a) shows a case where a flange of an upstream case part is integrally formed; The figure which shows a flange shape, (b) is a figure which shows the flange shape at the time of forming the flange of an upstream case part separately.
FIG. 3 is a schematic cross-sectional view showing a main configuration of an exhaust gas purification apparatus for an internal combustion engine as an embodiment of the present invention, where (a) is formed by narrowing the downstream end of the upstream case portion. (B) is sectional drawing at the time of forming without restrict | squeezing.
FIG. 4 is a diagram showing an overall configuration of an exhaust gas purification apparatus for an internal combustion engine as an embodiment of the present invention, and is a diagram comparing the size with a conventional apparatus.
FIG. 5 is a schematic diagram showing an overall configuration of a conventional exhaust purification device.
[Explanation of symbols]
4, 4a, 4b Upstream case (front case)
5 Downstream case (rear case)
6, 7 Case flange 10 Particulate filter (filter)
11 Filter flange 41 Body portion 42 of upstream case portion Case flange side portion of upstream case portion

Claims (1)

In an exhaust gas purification apparatus for an internal combustion engine in which a plurality of particulate filters are provided in parallel to each other in an exhaust path of the internal combustion engine,
Each of the above particulate filters is housed in a case that can be divided into an upstream case portion and a downstream case portion along the exhaust gas flow direction,
The upstream case portion is individually formed so as to accommodate each of the above particulate filters,
The downstream case portion is formed as a common case portion that houses both the particulate filters.
A case flange is formed at each connection portion between each upstream case portion and the downstream case portion, and a filter flange is formed on the outer periphery of the particulate filter.
By fastening the flanges so that the filter flange is sandwiched between the case flanges, the particulate filter is fixed to the case, and the case flange side portion of the upstream case portion is An exhaust emission control device for an internal combustion engine, characterized in that it is formed with a smaller diameter than the main body portion of the upstream case portion.

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