JP2006291909A - Exhaust system structure of on-vehicle engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To exhibit desired efficiency to the maximum by securing ventilation efficiency with the reduced cost. <P>SOLUTION: An attachment boss member 15a is fixed on DPF to which exhaust gas delivered from an engine is introduced, and a pressure takeout pipe 16a is welded to the DPF through the attachment boss part 15a in such a manner of capable of ventilating. The attachment boss member 15a is equipped with an insertion receiving part 152 of which outside diameter is gradually enlarged from its end in a predetermined length, and an annular receiving surface part 153 to which an end of the pressure takeout pipe 16a is abutted is provided on a base end side of the insertion receiving part 152. The pressure takeout pipe 16a is provided with an enlargement attachment part 162 enlarged along the insertion receiving part 152 on the end thereof, and is welded to the insertion receiving part 152 with the end of the enlargement attachment part 162 with the usage of a welding material 25 in the state that the end is abutted to the annular receiving surface part 153. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an in-vehicle engine in which a small-diameter pipe such as an exhaust pressure take-out pipe is welded to an exhaust system member through which exhaust gas discharged from a diesel engine or the like is vented, for example, a diesel particulate removing device (hereinafter simply referred to as “DPF”). This relates to the exhaust system structure.

  In recent years, in order to collect particulates (exhaust particulates such as soot) contained in exhaust gas discharged from a diesel engine, the diesel engine exhaust system has, for example, a catalytic function and collects the particulates. It is equipped with a DPF equipped with a filter. Since this DPF is clogged as it is used, it is generally regenerated by burning unburned fuel supplied to the exhaust system at a predetermined timing, for example. The predetermined timing for regenerating the DPF usually detects the exhaust pressure upstream or downstream of the filter in the DPF, and detects the pressure difference between the detected pressures, or the exhaust pressure and atmospheric pressure upstream of the filter. And is determined based on the pressure difference.

In such an exhaust system, in order to detect the exhaust pressure, for example, as disclosed in Patent Document 1, the exhaust system is provided with a predetermined portion of an exhaust system member such as an exhaust pipe positioned upstream of the DPF. In many cases, a pressure extraction pipe having a small diameter communicating with the inside is joined, and a pressure sensor for reading the pressure taken out by the pressure extraction pipe is provided. This pressure extraction pipe and an exhaust system member such as an exhaust pipe are usually joined in an airtight manner by inserting the pressure extraction pipe into an internal communication hole provided in the exhaust system member and welding in this state. In many cases, both are firmly attached.
JP 2003-42885 A

  By the way, the pressure extraction pipe is often formed with a small diameter and a thin wall as compared with a member to be joined such as an exhaust pipe. For this reason, when this pressure extraction pipe is welded to the member to be joined, the inner peripheral surface thereof may bulge due to the welding heat, and so-called back beads may be generated. When such a back bead occurs, there is a problem that the desired performance cannot be secured in the exhaust system structure, such as the air passage inside the pressure take-out pipe being blocked or narrowed and the pressure cannot be properly detected. there were.

  In particular, in the structure described in Patent Document 1, when the pressure extraction pipe is connected by welding, the heat capacity is extremely small as compared with the heat capacity of the member to be joined, so that the above problem appears remarkably.

  Here, in order to ensure the desired performance in such an exhaust system structure, instead of the above welding, a tapered male screw boss portion having a vent passage along the axial direction and having a male screw engraved around it is provided. It is also practiced that an exhaust system member is erected, a pressure take-out pipe is inserted into the male screw boss portion, and a nut is screwed onto the male screw so that both are pressure-tightly bonded. However, when such a joining structure is employed, precise processing is required to join the two in an airtight state, and high-precision parts increase, resulting in an increase in manufacturing cost.

  In view of the above circumstances, an object of the present invention is to provide an exhaust system structure for an in-vehicle engine that can ensure air permeability and maximize desired performance while suppressing manufacturing cost as much as possible.

  In the exhaust system structure of an in-vehicle engine according to the present invention, a mounting boss member is fixed to an exhaust system member through which exhaust gas discharged from the engine is vented, and a small-diameter pipe is vented to the exhaust system member through the mounting boss member. It is an exhaust system structure of an in-vehicle engine that is connected by welding in a possible state, and the mounting boss member has an outer diameter that gradually increases from the tip over a predetermined length while the inner diameter is maintained substantially constant. An insertion receiving portion that is expanded and fitted into one end portion of the small diameter pipe is provided, and a positioning portion that is in contact with one end of the small diameter pipe is provided on the base end side of the insertion receiving portion, The small-diameter pipe has an expansion attachment portion that is expanded along the insertion receiving portion at one end portion thereof, and one end portion of the expansion attachment portion in a state where one end thereof is in contact with the positioning portion. In the above insertion receiving part, it is welded using welding material. It is characterized in.

  According to this invention, since the small-diameter pipe is indirectly welded to the exhaust system member via the mounting boss member made of another member, the exhaust system member can be easily processed, and the manufacturing cost can be suppressed. it can. Moreover, for example, if a mounting boss member having a heat capacity between the heat capacity of the small diameter pipe and the heat capacity of the exhaust system member is selected, the exhaust system member and the mounting boss member, and the mounting boss member and the small diameter pipe are appropriately melted. It is possible to reliably and firmly weld, thereby improving the joint strength between the small-diameter pipe and the exhaust system member.

  In addition, the small diameter pipe is welded to the insertion receiving portion at one end of the expansion mounting portion in a state where the expansion mounting portion is externally fitted to the insertion receiving portion of the mounting boss member. The receiving portion functions as a backing material and can prevent the inner peripheral surface of the small-diameter pipe from bulging due to welding heat. In addition, since the insertion receiving portion is gradually expanded in diameter and has a sufficient thickness at the base end portion and is welded using a welding material, the inner peripheral surface of the mounting boss member is swelled by welding heat. It is possible to reliably prevent this. For this reason, it is possible to reliably prevent the air passage from the exhaust system member to the small-diameter pipe from being blocked or narrowed, thereby making it possible to maximize the desired performance of the exhaust system structure. Here, since the mounting boss member is provided with a positioning portion, the small diameter pipe can be securely fitted to the mounting boss member to a position where the insertion receiving portion can sufficiently perform its function, Since the welding is performed in this state, the above-described effects can be reliably and sufficiently extracted.

  Furthermore, since the insertion receiving part of the attachment boss member is welded in a state of being fitted into the expansion attachment part of the small-diameter pipe, it is possible to obtain a further joint strength by enlarging the joint surface between them. Since the bonding strength is improved in this way, durability can be improved regardless of vehicle vibration or the like.

  In addition, the expansion attachment part of the said small diameter pipe may be expanded beforehand, and when a small diameter pipe is externally fitted by the insertion receiving part, it is expanded by the insertion receiving part. It may be.

  Here, the specific configuration of the positioning portion is not particularly limited. For example, the positioning portion may be one or a plurality of bulging portions protruding from the peripheral surface of the mounting boss member. Is configured as an annular receiving surface portion formed by expanding the outer diameter of the mounting boss member stepwise, and the outer diameter of the annular receiving surface portion is formed larger than the outer diameter of the expanded mounting portion of the small-diameter pipe. (Claim 2).

  If comprised in this way, while positioning a small diameter pipe reliably by the annular receiving surface part formed in cyclic | annular form, this annular receiving surface part formed larger than the outer diameter of the expansion attachment part of a small diameter pipe becomes welding material. The joint strength between the small-diameter pipe and the exhaust system member can be further improved by fulfilling the function as the joint surface.

  In the present invention, the specific configurations and uses of the exhaust system member and the small-diameter pipe are not particularly limited. For example, the exhaust system member includes a filter for removing particulates contained in exhaust gas from a diesel engine. A diesel particulate removing device, wherein the small diameter pipe is connected to at least the upstream portion of the upstream portion and the downstream portion of the filter of the diesel particulate removing device and is a pressure extraction pipe for detecting the exhaust pressure flowing through the portion. It can be preferably applied (Claim 3).

  That is, a small-diameter pressure extraction pipe is often joined to the diesel particulate removal device of a diesel engine, and if the present invention is applied to an exhaust system structure including these, the pressure extraction pipe is configured to reduce the pressure at least upstream of the filter. Therefore, the pressure measurement accuracy can be improved.

  In this case, the diesel particulate removing device is provided with a heat insulating cover that covers at least a part of the main body, and the other end of the pressure take-out pipe is connected to the pressure sensor via a flexible hose, It is preferable that the predetermined part is attached to the heat insulating cover.

  If comprised in this way, the vibration etc. transmitted through a small diameter pressure extraction pipe can be suppressed by the attachment part of the middle part, and the junction part of a pressure extraction pipe and a diesel particulate removal device is protected from vibration etc. This can improve the durability.

  Thus, when the heat insulation cover is provided, it is preferable that the tip of the mounting boss member protrudes outside the heat insulation cover.

  With this configuration, it is possible to easily and properly attach the pressure extraction pipe with the heat insulating cover attached, thereby obtaining an exhaust system structure for an in-vehicle engine that can surely obtain the desired performance. it can.

  When the flexible hose is attached to the small-diameter pipe in this way, the diesel particulate removing device is connected to the diesel engine via an exhaust pipe including a flexible joint, and the pressure extraction pipe is connected to the exhaust gas flow. It is preferable that the cable is routed upstream to the vicinity of the flexible joint (claim 6).

  If comprised in this way, the vibration transmitted to a diesel particulate removal apparatus through members, such as an exhaust pipe, can also be suppressed by a flexible joint, and the junction part of this diesel particulate removal apparatus and a pressure extraction pipe is protected from vibration etc. This can improve the durability.

  In the present invention, the inner and outer diameters of the small-diameter pipe are not particularly limited, but the small-diameter pipe is set to have an outer diameter of 10 mm or less and an inner diameter of 4 mm or more other than the expanded mounting portion. (Claim 7).

  That is, when the outer diameter of the small-diameter pipe is larger than 10 mm, the influence of the so-called back bead is reduced, so there is little trouble even if the small-diameter pipe is directly welded to the exhaust system member, and the inner diameter is less than 4.0 mm This is because the air permeability may not be sufficiently secured.

  The method for forming an exhaust system structure for an in-vehicle engine according to the present invention is an exhaust system structure forming method for an in-vehicle engine in which a small-diameter pipe is welded to an exhaust system member through which exhaust gas exhausted from the engine is vented. An insertion receiving portion is provided in which the outer diameter is gradually increased from the tip over a predetermined length while the inner diameter is maintained substantially constant, and is fitted into one end of the small-diameter pipe. A boss fixing that fixes a mounting boss member provided with a positioning portion on which one end of the small-diameter pipe abuts on the base end side of the insertion receiving portion to an internal communication hole provided in the exhaust system member in an airtight state. A pipe fitting that fits outside the insertion receiving section until one end of the expansion mounting section of the small-diameter pipe having the expansion mounting section expanded along the insertion receiving section is in contact with the positioning section Combined process and this externally expanded installation It can be carried out by the end portion with a welding material and a welding step of welding to the plug receiving portion.

  According to the exhaust system structure of the in-vehicle engine according to the present invention, the inner peripheral surface of the mounting boss member can be surely prevented from expanding the inner peripheral surface of the small-diameter pipe by welding heat while suppressing the manufacturing cost. Can be reliably prevented from bulging due to welding heat, which can reliably prevent the air passage from the exhaust system member to the small-diameter pipe from being blocked or narrowed. There is an advantage that the desired performance in the system structure can be maximized. In addition, the small diameter pipe is externally fitted to the mounting boss member to a position where the insertion receiving portion can sufficiently perform its function by the positioning portion, and both are welded, and the above effect is sufficiently obtained. be able to. Further, the joint surface between the two can be enlarged to obtain further joint strength, and the durability can be improved regardless of the vibration of the vehicle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an exhaust system according to this embodiment in a state where an exhaust manifold and an exhaust supercharger are omitted. 2 and 3 are a plan view and a side view of the exhaust system.

  The exhaust system 4 of the present embodiment is applied to a diesel engine 3 mounted in an engine room in the front part of the vehicle. The exhaust system 4 extends in the front-rear direction of the vehicle body and emits exhaust gas generated as a result of combustion in the engine 3. It is released into the atmosphere from the rear of the vehicle body. Specifically, the exhaust system 4 includes an exhaust manifold 5 having upstream branch ends connected to a plurality of exhaust ports 31 of the diesel engine 3 (four in this embodiment), and a downstream merging end of the exhaust manifold 5. And an exhaust pipe 7 that guides exhaust gas discharged from the exhaust supercharger 6 from the front to the rear of the vehicle body and discharges it into the atmosphere. A diesel particulate removing device 8 (DPF 8) and a muffler 9 are interposed in the exhaust pipe 7.

  The exhaust manifold 5 is a pipe member that collects exhaust gas discharged from each cylinder (not shown) of the engine 3 and guides the exhaust gas to the downstream exhaust supercharger 6, and the upstream side is branched according to the exhaust port 31. At the same time, the branch pipes are joined downstream to guide the exhaust supercharger 6. As shown in FIG. 3, the exhaust manifold 5 of the present embodiment is formed with an upstream passage 51 of an EGR passage through which a part of the exhaust gas is introduced into the intake system.

  The exhaust supercharger 6 uses the energy of the exhaust flow to improve the efficiency of filling the engine 3 with air. The exhaust supercharger 6 includes a turbine 61 disposed in the exhaust passage and a compressor 62 that is coaxial with the turbine 61 and disposed in the intake passage, and drives the turbine 61 with an exhaust flow, whereby the compressor 62 is also driven, and the compressed air is sucked into the engine 3.

  As shown in FIG. 1, the exhaust pipe 7 includes a front pipe 7a extending from the exhaust supercharger 6 (see FIG. 2) to the DPF 8, a center pipe 7b extending from the DPF 8 to the muffler 9, and downstream of the muffler 9. A rear pipe (not shown) is provided, and these pipes 7a and 7b are routed so as to extend in the front-rear direction below the vehicle body.

  The front pipe 7a is bent and arranged so as to be inclined downwardly, and its upstream end is joined to the exhaust supercharger 6 by flange joining, and its downstream end is joined to the DPF 8 by the spherical joint 10a. Has been. The front pipe 7a includes first and second connecting pipes 71 and 72 connected in series via a spherical joint 10b similar to the spherical joint 10a which is a constituent member thereof.

  A specific configuration of the spherical joints 10a and 10b (corresponding to an example of a flexible joint) will be described. Since the two spherical joints 10a and 10b arranged upstream and downstream of the exhaust flow have the same configuration, the spherical joint 10b (front pipe 7a and DPF 8) arranged downstream is here. The spherical joint to be connected) will be described.

  As shown in FIG. 4, the spherical joint 10 b includes an annular flange 101 joined to the downstream end portion of the second connecting pipe 72 and a spherical flange joined to the upstream end of an upstream side connecting pipe portion 83 b described later of the DPF 8. 102, the gasket 103 interposed between the annular flange 101 and the spherical flange 102, and the annular flange 101 and the spherical flange 102 are elastically connected to elastically connect the front pipe 7a and the DPF 8. The annular flange 101 and the spherical flange 102 are arranged to face each other via the gasket 103, and in this state, the flanges 101 and 102 are connected by the elastic connection portion 107, so that the degree of freedom in bending is increased. It is comprised so that it may have. Therefore, the front pipe 7a is configured to be capable of rotational displacement with respect to the DPF 8.

  Specifically, the annular flange 101 is joined to a portion located on the upstream side of a predetermined length from the downstream end of the second connection pipe 72 so as to protrude outward in the radial direction of the second connection pipe 72. Has been. As a result, the downstream end portion of the second connecting pipe 72 is in a state protruding from the annular flange 101. The gasket 103 is attached to the peripheral surface of the projecting end of the second connecting pipe 72, and the gasket 103 is pressed against the spherical receiving surface 102a of the spherical flange 102, whereby the relative position of the second connecting pipe 72 with respect to the DPF 8 is reached. Even if there is a change in the airtightness, the airtightness between the front pipe 7a and the DPF 8 is ensured. The gasket 103 is an annular body formed in a substantially fan shape in cross section, and a portion that contacts the flanges 101 and 102 is formed along the shape.

  The elastic connecting portion 107 includes a bolt 104 that passes through the flange 101 and the spherical flange 102 from the annular flange 101 side, a nut 105 that is screwed to the bolt 104, a spherical flange 102 and a nut 105 that are inserted into the bolt 104. A plain washer plate 108 interposed between them, and an elastic material (a coil spring in this embodiment) 106 inserted into the bolt 104 and interposed between the spherical flange 102 and the plain washer plate 108, and a nut 105 as a bolt. The elastic member 106 is elastically deformed through a plain washer plate 108 by being screwed to 104, and the annular flange 101 and the spherical flange 102 are elastically connected by using this elastic recovery force.

  Since the front pipe 7a and the DPF 8 are elastically connected in this way, for example, even when the axial direction of the front pipe 7a is deviated from the axis of the upstream connection pipe portion 83b of the DPF 8, this deviation is absorbed and In addition to being able to be connected in an airtight state, vibration is effectively prevented from being transmitted to the DPF 8 through the front pipe 7a. Moreover, since the spherical joints 10a and 10b are also used for connection to the first and second connection pipes 71 and 72, vibration transmission to the DPF 8 of the engine 3 through the front pipe 7a is effectively prevented. can do.

  As shown in FIGS. 1 and 3, the first connection pipe 71 is supported by a crank-shaped pipe bracket 11 joined to the lower rear surface of the engine 3 at an intermediate portion thereof. Therefore, the exhaust system members interposed between the pipe bracket 11 and the engine 3, that is, the exhaust manifold 5 and the exhaust supercharger 6 are supported by the engine 3 from both sides. The support rigidity of the feeder 6 can be improved.

  Next, the DPF 8 connected to the front pipe 7a via the spherical joint 10a will be described. The DPF 8 is for ventilating and purifying exhaust gas discharged from the diesel engine 3, and in this embodiment, a catalyst member 81 for purifying harmful components (HC, CO, NOx) in the exhaust gas, It includes a particulate filter 82 (hereinafter simply referred to as “filter”) that collects particulates (exhaust particulates such as soot) contained in the exhaust gas.

  That is, as shown in FIGS. 3 and 5, the DPF 8 includes a catalyst member 81, a filter 82 arranged in series on the downstream side of the catalyst member 81, and the catalyst member 81 and the filter 82 in the internal gas flow passage. And a heat insulating cover 84 covering the outer peripheral surface of the DPF housing 83, particularly the outer peripheral surface corresponding to the catalyst member 81 and the filter 82, and the exhaust gas introduced into the DPF 8 The gas passes through the catalyst member 81 to remove harmful components contained in the exhaust gas, and the exhaust gas that has passed through the catalyst member 81 passes through the filter 82 to remove particulates contained in the exhaust gas. The exhaust gas is then discharged to the downstream side of the DPF 8. A heat insulating material such as a ceramic mat may be interposed between the DPF housing 83 and the heat insulating cover 84 to improve the heat insulating effect.

  The catalyst member 81 has an oxidizing action of HC (unburned fuel component) and CO in the exhaust gas, and a noble metal catalyst (for example, Pt and Pd are supported on γ-alumina on a honeycomb cordierite support. Is formed into a substantially cylindrical shape as a whole. Each cell of the catalyst member 81 formed in the honeycomb shape is opened at both ends, and the exhaust gas is circulated exclusively in the axial direction through each cell. On the other hand, the filter 82 is a honeycomb wall flow type made of cordierite, and is formed in a substantially cylindrical shape as a whole, and the end faces of each cell are alternately sealed so that the exhaust gas always moves between the cells. It is configured as follows.

  The DPF housing 83 includes a cylindrical housing main body 83a, an upstream connection pipe portion 83b connected to the upstream end of the housing main body 83a and gradually reduced in diameter and connected to the second connecting pipe 72 (front pipe 7a). A downstream connection pipe portion 83c connected to the downstream end of the housing body 83a and gradually reduced in diameter and connected to the center pipe 7b.

  The DPF 8 is configured to detect the pressure on the upstream side and the downstream side of the filter 82 and to be regenerated by a control unit (not shown) based on the detected pressure difference to prevent clogging. Therefore, one end portions of the pressure extraction pipes 16a and 16b are connected to predetermined portions of the DPF housing 83 on the upstream side and the downstream side of the filter 82 via the mounting boss members 15a and 15b, respectively.

  Specifically, the upstream mounting boss member 15a protrudes laterally at a predetermined portion of the lower half portion of the main body 83a of the housing 83 and corresponding to a portion between the catalyst member 81 and the filter 82. In addition to being joined by welding, the downstream mounting boss member 15b is joined to a predetermined portion of the lower half portion of the downstream connection pipe portion 83c by welding in a state of protruding sideways. The welding between the mounting boss member 15 and the DPF 8 is performed with the welding material in a state where the base end portion of the mounting boss member 15 is inserted into the mounting opening 83d (see FIG. 6) drilled in a predetermined portion of the housing 83. It is performed by the arc welding used (see FIGS. 6 and 7). As a result, the mounting boss member 15 and the DPF 8 are also joined by the welded portion 26.

  Although the upstream side and downstream side mounting boss members 15a and 15b are the same as each other although the mounting locations for the DPF 8 are different, the upstream side mounting boss member 15a will be described as an example here.

  As shown in FIGS. 6 and 7, the mounting boss member 15a is a substantially cylindrical boss member having a gas flow passage 151a having a substantially circular cross section extending linearly along the axial direction. The gas flow passage 151 a is configured to open into the DPF housing 83 on the upstream side of the filter 82, thereby communicating with the exhaust gas flow passage of the exhaust system 4. The length of the mounting boss member 15 a is set so as to protrude from the outer peripheral surface of the heat insulating cover 84 that covers the housing 83 in a state of being fixed to the DPF housing 83. Therefore, the pressure extraction pipe 16 can be easily joined in a state where the heat insulating cover 84 is attached to the DPF housing 83, thereby improving the reliability of the pressure extraction pipe 16 for joining.

  The mounting boss member 15a has an outer diameter that is gradually increased from the tip over a predetermined length in a tapered shape, and an insertion receiving portion 152 to which one end of the pressure extraction pipe 16a is connected. An annular receiving surface portion 153 formed by expanding the outer diameter in a step shape at the base end edge (end edge on the DPF 8 side) of the receiving portion 152, and a size cylinder shape from the annular receiving surface portion 153 to the base end portion on the DPF 8 side. The boss body 151 is provided, and an inner diameter d3 constituting the gas flow passage 151a is formed substantially constant over the entire length.

  As shown in FIG. 7, the insertion receiving portion 152 is formed in a substantially truncated cone shape as a result of the outer diameter being gradually increased from the tip (end edge opposite to the DPF 8). The insertion receiving portion 152 functions as a backing material when the distal end portion of the pressure extraction pipe 16a is externally fitted and welded to the pipe 16a. In the present embodiment, the outer diameter and the wall thickness at the distal end of the insertion receiving portion 152 are formed to be approximately the same as the outer diameter and wall thickness of a pipe body 161 described later of the pressure extraction pipe 16a. However, in the case where a later-described expansion attachment portion 162 of the pressure extraction pipe 16a is not previously expanded before assembling, the pressure extraction pipe is used from the viewpoint of ease of attachment and workability of the expansion attachment portion 162. It is preferably formed smaller than an inner diameter d1 of a pipe body 161 described later of 16a.

  Further, the inclination angle of the bus bar with respect to the axis of the insertion receiving portion 152 is not particularly limited, but is preferably set within a range of 30 ° to 60 °. When the inclination angle is less than 30 °, the ratio of the diameter increase decreases, and the thickness of the base end portion of the insertion receiving portion 152 becomes insufficient, and there is a possibility that it does not function sufficiently as a backing material. Further, if the inclination angle exceeds 60 °, the joint surface with the pressure take-out pipe 16a may be reduced and joint strength may be reduced. Therefore, it is preferable that the inclination angle of the insertion receiving portion 152 with respect to the axis of the bus is set within the above range.

  The annular receiving surface portion 153 is positioned in contact with the tip of the pipe 16a when the pressure extraction pipe 16a is assembled, and the joint surface of the welding material 25 used when welding the mounting boss member 15a and the pressure extraction pipe 16a. It also functions. The annular receiving surface portion 153 forms a plane whose normal line coincides with the axial direction of the mounting boss member 15a, and has an outer diameter larger than a distal end outer diameter of a later-described expanded mounting portion 162 of the pressure extraction pipe 16a. Has been. Therefore, as shown in FIG. 7, the outer peripheral edge of the annular receiving surface portion 153 is exposed in a state where the pressure take-out pipe 16a is attached to the attachment boss member 15a.

  On the other hand, the pressure extraction pipe 16a is a small-diameter, thin-walled cylindrical metal member formed of a steel pipe. This pressure extraction pipe 16a has a pipe body 161 whose inner diameter d1 is kept constant, and an expansion attachment section 162 that is expanded along the insertion receiving section provided at one end of the pipe body 161. In addition, a gas flow passage 161a communicating with the gas flow passage 151a of the mounting boss member 15a is formed along the axis. As described above, the pipe body 161 is formed with a small diameter and a thin wall. That is, the pipe body 161 is preferably set so that its inner diameter d1 is in the range of 4 to 9 mm, and its outer diameter d2 is in the range of 5 to 10 mm with a thickness of at least 0.5 mm or more secured. Is set. That is, when the outer diameter d2 of the pressure extraction pipe 16a is larger than 10 mm, the influence of the inner diameter d1 being changed by a so-called back bead is reduced, and when the inner diameter d1 is less than 4.0 mm, the exhaust gas permeability is reduced. This is because sufficient security cannot be secured.

  The expansion attachment portion 162 is formed to expand in a trumpet shape along the insertion receiving portion 152. The thickness of the expansion attachment portion 162 is substantially the same as the thickness of the pipe body 161. In this embodiment, the expansion attachment portion 162 that has been expanded in advance before the pressure extraction pipe 16a is assembled to the attachment boss member 15a is used. It has been. The outer diameter at the tip of the spread attachment portion 162 is formed smaller than the outer diameter of the annular receiving surface portion 153.

  The pressure extraction pipe 16a is attached to an attachment boss member 15a fixed to the DPF housing 83 as follows. That is, the expansion attachment portion 162 is directed toward the attachment boss member 15a, the pressure take-out pipe 16a is aligned with the axis of the attachment boss member 15a, and the tip of the expansion attachment portion 162 is connected to the annular receiving surface portion 153. The expansion attachment portion 162 is externally fitted to the insertion receiving portion 152 until it comes into contact. Then, in this assembled state, the expanding attachment portion 162 is welded to the insertion receiving portion 152 and the annular receiving surface portion 153 at the distal end portion using a welding material. As a result, the expansion mounting portion 162, the insertion receiving portion 152, and the annular receiving surface portion 153, in particular, the expansion mounting portion 162 and the insertion receiving portion 152 are melted and the welding material is melted, so that the pressure extraction pipe is firmly 16a and the mounting boss member 15a are joined. A welded portion 25 formed of a welding material is formed on the annular receiving surface portion 153 and around the distal end portion of the expanded mounting portion 162.

  As shown in FIGS. 2 and 5, the pressure extraction pipe 16a is routed along the side of the heat insulating cover 84 along the cover 84, and the other end 163 (front end) is a downstream spherical surface of the front pipe 7a. It extends to a position substantially opposite to the joint 10a. The pressure extraction pipe 16 a is supported by the bracket 23 a at the upstream end of the heat insulating cover 84. On the other hand, the pressure extraction pipe 16b is also routed along the cover 84 on the same side of the heat insulating cover 84 where the pressure extraction pipe 16a is wired, and the other end 163 (front end) of the front pipe 7a. It extends to a position substantially corresponding to the downstream spherical joint 10a. The pressure extraction pipe 16 b is also supported by the bracket 23 b at the downstream end of the heat insulating cover 84. The pressure extraction pipe 16b is also supported by the heat insulating cover 84 by the bracket 24 at the same position as the bracket 23a in the longitudinal direction of the vehicle body. The brackets 23 (23 a, 23 b) and 24 have base ends joined to the heat insulating cover 84 by bolts, and tip portions that hold the peripheral surfaces of the pressure extraction pipes 16.

  The tip portions 163 of the pressure extraction pipes 16 a and 16 b are both supported by the upstream diameter-reduced portion of the heat insulating cover 84 via the support bracket 18. The support bracket 18 has a central portion attached to the heat insulating cover 84 with bolts, and is configured to hold the pressure extraction pipes 16a and 16b at both ends in the vehicle width direction. Further, one end portion (rear end portion) of a connecting pipe 17 having flexibility (corresponding to an example of a flexible pipe) is connected to each distal end portion 163 of the pressure extraction pipe 16 in communication. The connecting pipe 17 is made of a heat-resistant soft synthetic resin, and bends following a change in the relative position between the front pipe 7a and the DPF 8. The connection pipe 17 is routed along the second connection pipe 72 in a state of being separated from the peripheral surface of the second connection pipe 72, and the other end is disposed at a position substantially corresponding to the upstream spherical joint 10b. Yes. That is, the connecting pipe 17 is disposed in a state substantially corresponding to the second connecting pipe 72 of the front pipe 7a in the vehicle longitudinal direction.

  A metal rigid pipe 19 made of a steel pipe is connected to the other end portion (front end portion) of each connecting pipe 17. Each rigid pipe 19 is supported on the front pipe 7 a by a pipe support bracket 20 in the vicinity of the connection portion with the connecting pipe 17. Each rigid pipe 19 is routed along the rear surface of the engine 3 and is connected to the pressure sensor 22 through a flexible hose 27.

  The pressure sensor 22 is attached to the upper front portion of the dash panel 21 and is configured to output a pressure difference between the upstream side and the downstream side of the filter 82 to a control unit (not shown). The control unit receives the output from the pressure sensor, and supplies the post-injected fuel to the exhaust gas in the engine 3 when the pressure difference between the upstream side and the downstream side of the filter 82 exceeds a predetermined pressure difference. Thus, the post-injected fuel is introduced into the DPF 8. The unburned fuel is burned in the catalyst member 81 or the filter 82 of the DPF 8, whereby particulates such as soot staying in the filter 82 are incinerated and removed to regenerate the DPF 8.

  Returning to the DPF 8, the DPF 8 is elastically supported below a floor panel (not shown) of the vehicle body by a mount rubber 12 provided in a state of projecting sideways at the upstream end thereof. The mount rubber 12 is provided with a vibration isolator, that is, a support device having a cylindrical rubber having an elliptical cross section, and has a large elasticity in the radial direction of the rubber, and absorbs vibrations in the radial direction. The vibration transmission from the vehicle body to the DPF 8 is suppressed. The mount rubber 12 of this embodiment is manufactured by aluminum die casting.

  Returning to FIG. 1, the center pipe 7 b is formed so that the upstream end thereof is connected to the downstream connection pipe portion 83 c of the DPF housing 83 and extends substantially straight rearward of the vehicle body. The center pipe 7b is elastically supported by the vehicle body by the mount rubber 13 at a position close to the DPF 8 at the upstream end thereof. The downstream end portion of the center pipe 7 b is connected to the muffler 9. The muffler 9 is for reducing exhaust discharge noise, and since a known one is used here, the description thereof is omitted. The muffler 9 is also elastically supported by the mount rubber 14. These mount rubbers 13 and 14 are also configured similarly to the mount rubber 12.

  The mount rubbers 12 and 13 that exclusively support the DPF 8 are arranged such that the axis thereof extends in the direction in which the exhaust system 4 extends. Accordingly, the DPF 8 has a small displacement with respect to the vehicle body in the longitudinal direction of the vehicle body, thereby effectively preventing unexpected extraction of each tubular member constituting the exhaust gas flow path of the exhaust system 4 and the exhaust gas path for pressure extraction. It is supposed to prevent.

  According to the exhaust system structure of the in-vehicle diesel engine configured as described above, the mounting opening 83d is formed in the DPF housing 83, and the mounting boss member 15 made of a separate member is attached to the mounting opening 83d. The DPF housing 83 can be easily processed at the time of manufacture. The mounting boss member 15 is designed so that its heat capacity is larger than the heat capacity of the pressure take-out pipe 16, in particular, its expanded mounting portion 162, and smaller than the heat capacity of the DPF housing 83. When welding 83 and the mounting boss member 15, the joints of the members 83 and 15 are appropriately melted and reliably and firmly welded, and when the mounting boss member 15 and the pressure extraction pipe 16 are welded. In addition, the joint portions of the members 15 and 16 are appropriately melted and reliably and firmly welded. As a result, the pressure extraction pipe 16 and the DPF housing 83 are compared with the case where the pressure extraction pipe 16 is directly welded to the DPF housing 83. The joint strength can be improved.

  Further, the pressure extraction pipe 16 is welded to the insertion receiving portion 152 at one end portion of the expansion mounting portion 162 in a state where the expansion mounting portion 162 is externally fitted to the insertion receiving portion 152 of the mounting boss member 15. Therefore, the insertion receiving portion 152 functions as a backing material for the expansion mounting portion 162, and thus, the swelling of the inner peripheral surface of the pressure extraction pipe 16 due to welding heat can be reliably prevented. Moreover, the diameter of the insertion receiving portion 152 is gradually increased, and the base end portion (the end portion on the DPF 8 side) has a sufficient thickness that is thicker than the thickness of the pressure extraction pipe 16, and the welded portion 25 made of a welding material. Therefore, it is possible to reliably prevent the inner peripheral surface of the mounting boss member 15 from bulging out due to the welding heat and changing the passage area and the sectional shape of the gas flow passage 151a. Therefore, it is possible to reliably prevent the gas flow passages 151a and 161a extending from the DPF housing 83 to the pressure extraction pipe 16 from being blocked or narrowed, and thereby exhaust the upper and lower flow portions of the filter 82 of the DPF 8. The pressure can be taken out properly, and the pressure measurement accuracy can be maintained and can be maintained in a good state without being varied depending on the structure when the plurality of exhaust systems 4 are configured.

  Further, the mounting boss member 15 is provided with an annular receiving surface portion 153, and is welded to the mounting boss member 15 in a state where the pressure boss pipe 16 is surely positioned at an appropriate position without variation when the pressure extraction pipe 16 is mounted. Even when the exhaust system 4 is manufactured, there is no variation and the above effect can be obtained with certainty.

  Moreover, since the outer peripheral surface of the insertion receiving portion 152 of the mounting boss member 15 and the inner peripheral surface of the expansion mounting portion 162 of the pressure extraction pipe 16 are welded and surface-bonded, the mounting boss member 15 and the pressure extraction pipe 16 can be improved in bonding strength. That is, as described above, the joint strength between the pressure extraction pipe 16 and the DPF housing 83 is drastically coupled with the attachment of the pressure extraction pipe 16 to the housing 83 indirectly through the mounting boss member 15. Can be improved. Thus, since the joint strength of both the members 16 and 83 is improved, durability against the joint can be improved regardless of the vibration of the vehicle.

  The DPF 8 is connected to the diesel engine 3 via a front pipe 7a including a pair of upstream and downstream spherical joints 10a, 10b having a degree of freedom of bending, and is elastically supported by the vehicle body by mount rubbers 12, 13. Since the pressure extraction pipe 16 is supported by the heat insulating cover 84 of the DPF 8 by the bracket 23 near the mounting boss member 15, the pressure extraction pipe 16 is transmitted to the joint portion between the pressure extraction pipe 16 and the DPF housing 83 via the mounting boss member 15. Such vibrations are absorbed by the mount rubbers 12 and 13 and the bracket 23. Therefore, since the joint part of both the members 16 and 83 is protected from vibration etc., the durability can be further improved.

  In addition, the exhaust gas flow passage from the DPF 8 to the pressure sensor 22 is composed of metal pipes 16 and 19 made of steel pipes or the like for portions that are in a relatively high temperature atmosphere, such as the DPF 8 and the engine 3. , 19 and the DPF 8 or the engine 3 can be prevented to prevent the pipes 16 and 19 from being damaged, and the support rigidity of the pipes 16 and 19 can be improved. On the other hand, an exhaust gas flow path from the DPF 8 to the pressure sensor 22 is provided correspondingly between the front pipe 7a including the spherical joints 10a and 10b and a relatively remote vehicle-mounted member (the engine 3 and the pressure sensor 22). Since it is constituted by the connecting pipe 17 having flexibility, etc., it can be deformed following the relative displacement between the engine 3 and the DPF 8 and the relative displacement between the engine 3 and the dash panel 21. It is possible to effectively prevent the pipes 16, 17, 19 and the like from being fatigued and to effectively prevent them from being damaged.

  The exhaust system structure of the in-vehicle engine described above is an embodiment of the structure according to the present invention, and the specific configuration and the like can be changed as appropriate without departing from the spirit of the present invention. Hereinafter, the modification is demonstrated.

  (1) In the above-described embodiment, the expansion attachment portion 162 of the pressure extraction pipe 16 is preliminarily expanded, but when the pressure extraction pipe 16 is externally fitted to the insertion receiving portion 152. It may be expanded by the insertion receiving part 152.

  (2) In the above embodiment, the pressure take-out pipes 16a and 16b are routed along the DPF housing 83, and are arranged at positions corresponding to the downstream spherical joint 10a in a state where the tip portions 163 are aligned with each other. However, the arrangement route of the pressure extraction pipes 16a and 16b and the arrangement position of the tip end thereof are not particularly limited, and may be configured as shown in FIG. 8, for example. In FIG. 8, the arrangement path of the downstream pressure extraction pipe 16b and the arrangement position of the distal end portion 216 are the same as those in the above embodiment, but the arrangement position of the distal end portion 217 of the upstream pressure extraction pipe 16a is the same. Different from the above embodiment.

  That is, the distal end portion 216 of the downstream pressure extraction pipe 16b is disposed along the longitudinal direction of the DPF 8, while the distal end portion 217 of the upstream pressure extraction pipe 16a is disposed in an inclined state with respect to the longitudinal direction of the DPF 8. Has been. And the front-end | tip of this front-end | tip part 217 is arrange | positioned in the back side compared with the front-end | tip of the front-end | tip part 216 of the downstream pressure extraction pipe 16b.

  (3) In the above embodiment, the positioning portion is configured as the annular receiving surface portion 153, but the specific configuration is particularly limited as long as the positioning portion can be positioned in contact with the tip of the pressure extraction pipe. Instead, for example, it may be configured as one or a plurality of protrusions protruding from the peripheral surface of the mounting boss member 15. However, when the positioning portion is configured as the annular receiving surface portion 153 as in the above embodiment, the entire circumference of the tip of the pressure extracting pipe 16 is brought into contact with the annular receiving surface portion 153, whereby the pressure extracting pipe 16 There is an advantage that the positioning is performed reliably and the annular receiving surface portion 153 can function as a joining surface of the welding material to further improve the joining strength between the pressure extraction pipe and the DPF 8.

  (4) In the above embodiment, the pair of spherical joints 10a and 10b are used for the front pipe 7a. However, instead of at least one of the spherical joints 10a and 10b, a flexible tube formed in a bellows shape is used. It may be used.

1 is a perspective view showing an exhaust system including an exhaust structure of an in-vehicle engine according to the present invention in a state where an exhaust manifold and an exhaust supercharger are omitted. It is a top view of the exhaust system. It is a side view of the same exhaust system. It is sectional drawing which shows the spherical joint contained in the exhaust system. It is a partially notched bottom view which shows DPF contained in the same exhaust system. It is sectional drawing which shows the joining structure of the pressure extraction pipe with respect to a DPF housing. It is a perspective view which shows the junction structure. It is a top view which shows DPF which concerns on other embodiment.

Explanation of symbols

3 Diesel engine 7 Exhaust pipe 7a Front pipe 7b Center pipe 8 Diesel particulate removal device (DPF)
10a Downstream spherical joint (an example of a flexible joint)
10b Upstream spherical joint (an example of a flexible joint)
DESCRIPTION OF SYMBOLS 15 Mounting boss member 15a Upstream side mounting boss member 15b Downstream side mounting boss member 16 Pressure extraction pipe 16a Pressure extraction pipe 16b Pressure extraction pipe 17 Connection pipe (an example of flexible pipe)
22 pressure sensor 23 bracket 25 welded portion 83 DPF housing 83d mounting opening 84 heat insulating cover 152 insertion receiving portion 153 annular receiving surface portion 161 pipe main body 161a gas flow passage 162 widening mounting portion

Claims (7)

A mounting boss member is fixed to an exhaust system member through which exhaust gas exhausted from the engine is vented, and a small-diameter pipe is connected to the exhaust system member via the mounting boss member by welding so as to be ventilated. An exhaust system structure,
The mounting boss member has an insertion receiving portion in which the outer diameter is gradually expanded from the tip over a predetermined length while the inner diameter is maintained substantially constant, and is fitted into one end of the small-diameter pipe. And a positioning portion on which one end of the small-diameter pipe is brought into contact with the base end side of the insertion receiving portion,
The small-diameter pipe has an expansion attachment portion that is expanded along the insertion receiving portion at one end portion thereof, and one end portion of the expansion attachment portion in a state where one end thereof is in contact with the positioning portion. An exhaust system structure for an in-vehicle engine, wherein the plug receiving portion is welded using a welding material.   The positioning portion is configured as an annular receiving surface portion formed by expanding the outer diameter of the mounting boss member stepwise, and the outer diameter of the annular receiving surface portion is larger than the outer diameter of the expanded mounting portion of the small-diameter pipe. 2. The exhaust system structure for an in-vehicle engine according to claim 1, wherein the exhaust system structure is large.   The exhaust system member is a diesel particulate removal device including a filter that removes particulates contained in exhaust gas from a diesel engine, and the small-diameter pipe is disposed at least upstream of the upstream portion and the downstream portion of the filter of the diesel particulate removal device. The exhaust system structure for an in-vehicle engine according to claim 1 or 2, wherein the exhaust system structure is a pressure extraction pipe for detecting an exhaust pressure connected and flowing through the portion.   The diesel particulate removing device is provided with a heat insulating cover that covers at least a part of the main body, and the other end of the pressure extraction pipe is connected to a pressure sensor via a flexible hose, and a predetermined portion of the intermediate portion is The exhaust system structure for an in-vehicle engine according to claim 3, wherein the exhaust system structure is attached to the heat insulating cover.   The exhaust system structure for an in-vehicle engine according to claim 4, wherein a tip of the mounting boss member protrudes outward from the heat insulating cover.   The diesel particulate removing device is connected to a diesel engine through an exhaust pipe including a flexible joint, and the pressure extraction pipe is routed upstream of the exhaust gas flow to a position near the flexible joint. An exhaust system structure for an in-vehicle engine according to claim 4 or 5.   The said small diameter pipe is set to the outer diameter of parts other than the said expansion attachment part below 10 mm, and the internal diameter is set to 4 mm or more, The any one of Claim 1 thru | or 6 characterized by the above-mentioned. Exhaust system structure of in-vehicle engine.

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