JP5990123B2 - Engine exhaust purification system - Google Patents

Description

  The present invention relates to an engine exhaust purification device, and more particularly to an engine exhaust purification device capable of reducing the amount of exhaust noise emission.

2. Description of the Related Art Conventionally, there are the following engine exhaust gas purification apparatuses (see, for example, Patent Document 1).
As shown in FIG. 6, the exhaust gas is provided with an exhaust gas purification part (101) and an exhaust gas outlet case (102), and the exhaust gas outlet part (101) faces the exhaust gas outlet end surface (101a) in the exhaust gas outlet case (102). An outlet chamber (102a) is provided, an exhaust outlet pipe (103) is inserted along the radial direction of the exhaust outlet chamber (102a), and a pipe end portion (103a) downstream of the exhaust outlet pipe (103) is exhausted. An engine exhaust gas purification apparatus that protrudes outward from the peripheral wall (102b) of the outlet case (102) and has a plurality of exhaust introduction holes (103c) opened in the peripheral wall (103b) of the exhaust outlet pipe (103).

  However, this prior art has a problem because the exhaust introduction hole (103c) is formed over the entire length of the exhaust outlet pipe (103) in the exhaust outlet chamber (102a) as shown in FIG.

Japanese Patent Laying-Open No. 2011-99416 (see FIG. 2)

<Problem> Exhaust noise emissions are large.
As shown in FIG. 6, since the exhaust introduction hole (103c) is formed over the entire length of the exhaust outlet pipe (103) in the exhaust outlet chamber (102a), the exhaust introduction hole near the pipe end portion (103a). The distance from (103c) to the pipe end (103a) is short, and the exhaust (113) flowing into the exhaust outlet pipe (103) from the exhaust introduction hole (103c) near the pipe end (103a) Flows into the pipe end (103a) without being sufficiently attenuated.
In particular, as indicated by an arrow in FIG. 6, the exhaust gas purifier 101 travels straight from the vicinity of the start end side edge 101 c on the pipe start end portion 103 d side of the exhaust outlet end surface 101 a, and the exhaust outlet pipe ( The exhaust (113) flowing in from the exhaust introduction hole (103c) on the front end side of 103) does not collide once in the exhaust outlet pipe (103) in the exhaust outlet chamber (102a). The vibration flows out to the pipe end portion (103a) without being attenuated.
For this reason, the pressure vibration of the exhaust (113) vibrates vigorously in the pipe end portion (103a) and the downstream exhaust path, resulting in a large amount of exhaust noise emission.

  An object of the present invention is to provide an exhaust emission control device for an engine that can reduce an emission amount of exhaust noise.

Invention specific matters of the invention according to claim 1 are as follows.
As shown in FIGS. 1A, 1B, and 2, an exhaust purification unit (1) and an exhaust outlet case (2) are provided, and the exhaust of the exhaust purification unit (1) is provided in the exhaust outlet case (2). An exhaust outlet chamber (2a) facing the outlet end face (1a) is provided, and an exhaust outlet pipe (3) is inserted in the exhaust outlet chamber (2a) along the radial direction thereof, downstream of the exhaust outlet pipe (3). Side pipe end (3a) protrudes outward from the peripheral wall (2b) of the exhaust outlet case (2), and a plurality of exhaust introduction holes (3c) are opened in the peripheral wall (3b) of the exhaust outlet pipe (3) In an engine exhaust purification system,
As illustrated in FIGS. 1 (A) and 2, the exhaust outlet pipe (3) in the exhaust outlet chamber (2a) includes a non-porous pipe portion (4) having no exhaust introduction hole (3c) and an exhaust introduction hole. (3c) and a perforated pipe part (5), a non-perforated pipe part (4) is arranged on the pipe end part (3a) side, and a perforated pipe part (5) is an exhaust outlet pipe (3). Arranged on the upstream pipe start end (3d) side,
As illustrated in FIG. 2, the central axis of the exhaust purification unit (1) when viewed from the direction orthogonal to the central axis (1 b) of the exhaust purification unit (1) and the central axis (3 e) of the exhaust outlet pipe (3). A boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided closer to the pipe start end (3d) than (1b) ,
As illustrated in FIG. 2, the exhaust purification unit (1) is one of a DPF (20), an oxidation catalyst, a reduction catalyst, and a three-way catalyst, and the exhaust outlet end face (1a) of the exhaust purification unit (1) is an exhaust gas. The direction is perpendicular to the central axis (1b) of the purification section (1),
With respect to the exhaust outlet pipe (3), the side with the exhaust purification section (1) is the front side, the opposite side is the rear side, the pipe start end (3d) side is the start end side, and the pipe end end (3a) side is the end side. ,
On a sectional view cut along a plane along the central axis (1b) of the exhaust purification section (1) and the central axis (3e) of the exhaust outlet pipe (3),
The first imaginary line (7) extending from the start end side edge (1c) of the exhaust outlet end face (1a) of the exhaust purification section (1) and the rear end side inner peripheral surface (2c) of the exhaust outlet case (2) (7) ) On the first imaginary line (7), the rear side of the exhaust outlet pipe (3) from the rear inner peripheral surface (3f) by the dimension (8) equal to the inner diameter dimension (8) of the exhaust outlet pipe (3). The first imaginary point (9) biased to the second imaginary line connecting the first imaginary point (9) and the start end side edge (1c) of the exhaust outlet end face (1a) of the exhaust purification section (1) ( 10), a second imaginary point (11) at which the second imaginary line (10) and the front inner peripheral surface (3g) of the exhaust outlet pipe (3) intersect, and a rearward direction from the second imaginary point (11) Assuming a third imaginary line (12) orthogonal to the central axis (3e) of the exhaust outlet pipe (3),
An exhaust emission control device for an engine, characterized in that a boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided on the start end side of the third imaginary line (12).

(Invention of Claim 1)
The invention according to claim 1 has the following effects.
<Effect> The emission amount of exhaust noise can be reduced.
As illustrated in FIG. 2, the central axis of the exhaust purification unit (1) when viewed from the direction orthogonal to the central axis (1 b) of the exhaust purification unit (1) and the central axis (3 e) of the exhaust outlet pipe (3). Since the boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided closer to the pipe start end (3d) than (1b), the emission amount of exhaust noise should be reduced. Can do.

The reason is presumed as follows.
The non-porous pipe portion (4) becomes sufficiently long, and the exhaust (13) flowing into the exhaust outlet pipe (3) from the exhaust introduction hole (3c) passes through the long non-porous pipe portion (5). After the pressure vibration is attenuated by the collision of the non-porous pipe portion (4) with the peripheral wall and the mutual interference between the exhausts (13), it flows out to the pipe end portion (3a).

In particular, it goes straight from the vicinity of the start end side edge (1c) of the exhaust outlet end face (1a) of the exhaust purification section (1), and from the exhaust introduction hole (3c) on the front end side of the exhaust outlet pipe (3). Even the exhaust gas (13) flowing into the pipe (3) always collides with the rear inner peripheral surface (3f) of the non-porous pipe portion (4), so that at least 1 in the non-porous pipe portion (4). The exhaust (13) collides with each other, and after the pressure vibration is attenuated by this collision, the exhaust (13) flows out to the pipe end portion (3a). In this case, the collided exhaust gas (13) vibrates the peripheral wall of the non-porous pipe portion (4), but the vibration pressure is released to the exhaust outlet chamber (2a), so that vibration of the pipe end portion (3a) is not affected. The amount of transmission is small.
For this reason, the vibration of the pipe end portion (3a) and the downstream exhaust path is suppressed, and the emission amount of the exhaust noise can be reduced.

<Effect> The emission amount of exhaust noise can be reduced.
As illustrated in FIG. 2, since the boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided on the start end side with respect to the third imaginary line (12), the exhaust noise is reduced. The amount of release can be reduced.

The reason is presumed as follows.
On the cross-sectional view illustrated in FIG. 2, a third virtual point (14) where the second virtual line (10) and the rear inner peripheral surface (3 f) of the exhaust outlet pipe (3) intersect, and the third virtual point A fourth imaginary line (15) extending forward from (14) and orthogonal to the central axis (3e) of the exhaust outlet pipe (3), and a second imaginary line (10) with respect to the fourth imaginary line (15), Assuming a line-symmetric fifth imaginary line (16) and a fourth imaginary point (17) where the fifth imaginary line (16) and the front inner peripheral surface (3g) of the exhaust outlet pipe (3) intersect, The four imaginary points (17) are located on the end side inner peripheral surface (2c) of the exhaust outlet case (2).
If the exhaust gas advances straight along the second imaginary line (10) from the starting end side edge (1c) of the exhaust outlet end surface (1a) of the exhaust gas purification unit (1), the exhaust gas passes through the third imaginary point (14 ) Collides with the rear inner peripheral surface (3f) of the exhaust outlet pipe (3), reflects to the front side along the fifth virtual line (16), and terminates in the inner peripheral surface (2c) of the exhaust outlet case (2). A fourth virtual point (17) in the vicinity is reached.

For this reason, when the boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided on the start end side of the third imaginary line (12), as shown by the arrow in FIG. The exhaust outlet pipe (3) goes straight from the vicinity of the start end edge (1c) of the exhaust outlet end face (1a) of the part (1) and from the exhaust introduction hole (3c) on the front end side of the exhaust outlet pipe (3). Even if the exhaust gas (13) flows into the interior, it always collides with the rear inner peripheral surface (3f) of the non-porous pipe portion (4), reflects to the front side, and enters the front side of the non-porous pipe portion (4). Since it collides with the peripheral surface (3g), the exhaust (13) collides at least twice in the non-porous pipe portion (4), and after the pressure vibration is attenuated by the collision, the exhaust (13) It flows out to a part (3a). In this case, the collided exhaust gas (13) vibrates the peripheral wall of the non-porous pipe portion (4), but the vibration pressure is released to the exhaust outlet chamber (2a), so that vibration of the pipe end portion (3a) is not affected. The amount of transmission is small.
Thereby, the vibration of the pipe end portion (3a) and the exhaust path downstream thereof is suppressed, and the emission amount of exhaust noise can be reduced.

FIG. 1A is a perspective view of an exhaust outlet case, and FIG. 1B is a cross-sectional plan view of the exhaust purification apparatus and the exhaust outlet case according to an embodiment of the present invention. . It is the II-II sectional view taken on the line of FIG. 3A is a cross-sectional view taken along line IIIA-IIIA in FIG. 2, and FIG. 3B is a cross-sectional view taken along line IIIB-IIIB in FIG. 4A is a front view of the exhaust outlet end face of the exhaust purification section used in the exhaust purification apparatus shown in FIG. 1, and FIGS. 4B to 4H are views of the exhaust outlet end face of the exhaust purification section according to the modification. It is a front view. FIG. 2 is a side view of the exhaust purification device of FIG. 1. It is sectional drawing of the exhaust emission purification device of the engine which concerns on a prior art.

  FIGS. 1 to 5 are views for explaining an engine exhaust gas purification apparatus according to an embodiment of the present invention. In this embodiment, an exhaust gas purification apparatus for a diesel engine will be described.

The outline of this exhaust gas purification device is as follows.
As shown in FIG. 5, the exhaust emission control device includes a DPF storage case (18), an exhaust inlet case (19), and an exhaust outlet case (2). The DPF storage case (18) includes a DPF (20). The DOC (21) is accommodated in the exhaust inlet case (19). An exhaust inlet pipe (22) is inserted into the exhaust inlet case (19), and an exhaust outlet pipe (3) is inserted into the exhaust outlet case (2).
In this exhaust purification device, PM in the exhaust (13) is captured by the DPF (20), and when the accumulated amount of PM in the DPF (20) reaches a predetermined amount, it is injected into the exhaust (13) by post injection. The unburned fuel is catalytically combusted in the DOC (21), the temperature of the exhaust (13) is raised, PM deposited on the DPF (20) is incinerated and removed, and the DPF (20) is regenerated.
DPF is a diesel particulate filter, DOC is a diesel oxidation catalyst, and PM is an abbreviation for particulate matter contained in exhaust gas.

As shown in FIG. 5, the exhaust inlet case (19) and the exhaust outlet case (2) are both fastened to the upstream side and the downstream side of the DPF housing case (18) by fastening bands (23) and (23). Yes.
As shown in FIG. 2, the DPF (20) is a cylindrical ceramic filter, and the inside thereof has a honeycomb structure and includes a plurality of cells (1d) (1d) extending in the axial length direction, and adjacent cells (1d). (1d) Inlet and outlet are alternately plugged, and the exhaust passes through the porous wall (1e) between the cells (1d) and (1d), and the porous wall (1e) captures PM in the exhaust. It is of flow type.
As shown in FIG. 5 , a pair of pressure derivation pipes (24) and (24) are led out from the exhaust inlet case (19) and the exhaust outlet case (2), and a differential pressure sensor (25) is provided at these outlet ends. The differential pressure between the upstream side and the downstream side of the DPF (20) is detected, and the PM accumulation amount in the DPF (20) is estimated by an engine ECU (not shown) based on the detected value of the differential pressure. . Engine ECU is an abbreviation for engine electronic control unit.
DOC (21) is a columnar ceramic carrier on which an oxidation catalyst component is supported. The inside of the carrier has a honeycomb structure and includes a plurality of cells extending in the axial direction, and the oxidation catalyst component is contained in the cell. Is a through flow type that allows exhaust to pass through the cell.

  As shown in FIGS. 1A, 1B, and 2, the exhaust purification device includes an exhaust purification unit (1) and an exhaust outlet case (2), and an exhaust purification unit (2) is provided in the exhaust outlet case (2). 1) An exhaust outlet chamber (2a) facing the exhaust outlet end face (1a) is provided, and an exhaust outlet pipe (3) is inserted into the exhaust outlet chamber (2a) along the radial direction thereof. 3) A downstream pipe end portion (3a) projects outward from the peripheral wall (2b) of the exhaust outlet case (2), and a plurality of exhaust introduction holes (3c) are formed in the peripheral wall (3b) of the exhaust outlet pipe (3). Is open.

As shown in FIGS. 1 (A), 1 (B), and 2, the exhaust purification unit (1) is a DPF (20). The DPF storage case (18) has a cylindrical shape, and a heat insulating cushion material (26) of glass wool is provided between the DPF storage case (18) and the outer peripheral surface of the DPF (20) . The exhaust outlet case (2) has a bowl shape in which one end of a cylinder is closed, and the exhaust outlet pipe (3) along its radial direction has a cylindrical shape.
As shown in FIG. 4 (A), the exhaust outlet end face (1a) of the exhaust purification section (1) is a perfect circle when viewed in a direction parallel to the central axis (1b) of the exhaust purification section (1). 4B, an oval shape as shown in FIGS. 4C and 4D, an oval shape as shown in FIGS. 4E and 4F, and FIGS. 4G and 4H. A rectangle as shown in FIG.
These exhaust outlet end faces (1a) are all oriented in a direction perpendicular to the central axis (1b) of the exhaust purification section (1) and viewed in a direction parallel to the central axis (1b) of the exhaust purification section (1). Assuming an orthogonal virtual line (27) orthogonal to the central axis (3e) of the exhaust outlet pipe (3) and the central axis (1b) of the exhaust purification section (1), the central axis of the exhaust outlet pipe (3) (3e) and the imaginary line (27) are symmetrical with respect to the line.
In this embodiment, the exhaust purification unit (1) is a DPF (20), but the exhaust purification unit (1) may be an oxidation catalyst or a reduction catalyst. In the case of a spark ignition engine, a three-way catalyst is used. It may be.

As shown in FIGS. 1 (A) and 2, the exhaust outlet pipe (3) in the exhaust outlet chamber (2a) includes a non-porous pipe portion (4) having no exhaust introduction hole (3c) and an exhaust introduction hole ( 3c) with a perforated pipe part (5), a non-perforated pipe part (4) is arranged on the pipe end part (3a) side, and a perforated pipe part (5) of the exhaust outlet pipe (3) It is arranged on the upstream pipe start end (3d) side.
As shown in FIG. 2, the central axis (1) of the exhaust purification unit (1) is viewed from a direction orthogonal to the central axis (1b) of the exhaust purification unit (1) and the central axis (3e) of the exhaust outlet pipe (3). A boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided closer to the pipe start end (3d) than 1b).

As shown in FIG. 3A, the non-porous pipe portion (4) is not provided with an exhaust introduction hole. As shown in FIG. 1 (A) and FIG. 2, the peripheral wall of the perforated pipe portion (5) is provided with a plurality of exhaust introduction holes (3c) side by side along its axial length direction. As shown in FIGS. 2 and 3B, the rows of the exhaust introduction holes (3c) are arranged over the entire circumference of the peripheral wall of the perforated pipe portion (5).
As shown in FIGS. 1A and 2, the boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is a tangent line that is in contact with the plurality of exhaust introduction holes (3c) on the most end side. Can be specified by.

As shown in FIG. 2, with respect to the exhaust outlet pipe (3), the side with the exhaust purification section (1) is the front side, the opposite side is the rear side, the pipe start end (3d) side is the start end side, and the pipe end section ( The 3a) side is the end side.
As shown in FIG. 2, on the sectional view cut along the plane along the central axis (1b) of the exhaust purification section (1) and the central axis (3e) of the exhaust outlet pipe (3), the following configuration is formed. .
The first imaginary line (7) extending from the start end side edge (1c) of the exhaust outlet end face (1a) of the exhaust purification section (1) and the rear end side inner peripheral surface (2c) of the exhaust outlet case (2) (7) ) On the first imaginary line (7), the rear side of the exhaust outlet pipe (3) from the rear inner peripheral surface (3f) by the dimension (8) equal to the inner diameter dimension (8) of the exhaust outlet pipe (3). The first imaginary point (9) biased to the second imaginary line connecting the first imaginary point (9) and the start end side edge (1c) of the exhaust outlet end face (1a) of the exhaust purification section (1) ( 10), a second imaginary point (11) at which the second imaginary line (10) and the front inner peripheral surface (3g) of the exhaust outlet pipe (3) intersect, and a rearward direction from the second imaginary point (11) And a third imaginary line (12) orthogonal to the central axis (3e) of the exhaust outlet pipe (3).
When assumed in this way, the boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided on the start end side with respect to the third imaginary line (12).

(1) Exhaust gas purification unit
(1a) Exhaust outlet end face
(1b) Center axis
(1c) Start side edge
(2) Exhaust outlet case
(2a) Exhaust outlet chamber
(2b) Perimeter wall
(2c) End side inner peripheral surface
(3) Exhaust outlet pipe
(3a) Pipe end
(3b) Perimeter wall
(3c) Exhaust introduction hole
(3d) Pipe start end
(3e) Center axis
(3f) Rear inner peripheral surface
(3g) Front inner peripheral surface
(4) Non-porous pipe part
(5) Perforated pipe part
(6) Boundary
(7) First imaginary line
(8) Inner diameter dimensions
(9) First virtual point
(10) Second virtual line
(11) Second virtual point
(12) Third virtual line

Claims (1)

An exhaust purification chamber (1) and an exhaust outlet case (2) are provided, and an exhaust outlet chamber (2a) is provided in the exhaust outlet case (2) with the exhaust outlet end face (1a) facing the exhaust purification section (1). The exhaust outlet pipe (3) is inserted into the exhaust outlet chamber (2a) along the radial direction, and the pipe end portion (3a) on the downstream side of the exhaust outlet pipe (3) is the peripheral wall of the exhaust outlet case (2). (2b) in an engine exhaust gas purification device in which a plurality of exhaust gas introduction holes (3c) are opened on the peripheral wall (3b) of the exhaust outlet pipe (3).
The exhaust outlet pipe (3) in the exhaust outlet chamber (2a) includes a non-perforated pipe portion (4) having no exhaust introduction hole (3c) and a perforated pipe portion (5) having an exhaust introduction hole (3c). The non-porous pipe part (4) is arranged on the pipe end part (3a) side, and the perforated pipe part (5) is arranged on the pipe start end part (3d) side upstream of the exhaust outlet pipe (3). ,
When viewed from a direction orthogonal to the central axis (1b) of the exhaust purification unit (1) and the central axis (3e) of the exhaust outlet pipe (3), the pipe start end portion is more than the central axis (1b) of the exhaust purification unit (1). On the (3d) side, a boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided,
The exhaust purification unit (1) is one of a DPF (20), an oxidation catalyst, a reduction catalyst, and a three-way catalyst, and the exhaust outlet end face (1a) of the exhaust purification unit (1) is the central axis of the exhaust purification unit (1) The direction is orthogonal to (1b),
With respect to the exhaust outlet pipe (3), the side with the exhaust purification section (1) is the front side, the opposite side is the rear side, the pipe start end (3d) side is the start end side, and the pipe end end (3a) side is the end side. ,
On a sectional view cut along a plane along the central axis (1b) of the exhaust purification section (1) and the central axis (3e) of the exhaust outlet pipe (3),
The first imaginary line (7) extending from the start end side edge (1c) of the exhaust outlet end face (1a) of the exhaust purification section (1) and the rear end side inner peripheral surface (2c) of the exhaust outlet case (2) (7) ) On the first imaginary line (7), the rear side of the exhaust outlet pipe (3) from the rear inner peripheral surface (3f) by the dimension (8) equal to the inner diameter dimension (8) of the exhaust outlet pipe (3). The first imaginary point (9) biased to the second imaginary line connecting the first imaginary point (9) and the start end side edge (1c) of the exhaust outlet end face (1a) of the exhaust purification section (1) ( 10), a second imaginary point (11) at which the second imaginary line (10) and the front inner peripheral surface (3g) of the exhaust outlet pipe (3) intersect, and a rearward direction from the second imaginary point (11) Assuming a third imaginary line (12) orthogonal to the central axis (3e) of the exhaust outlet pipe (3),
An exhaust emission control device for an engine, characterized in that a boundary (6) between the non-porous pipe portion (4) and the perforated pipe portion (5) is provided on the start end side of the third imaginary line (12).

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