CN1392920A

CN1392920A - Exhaust system of IC engines

Info

Publication number: CN1392920A
Application number: CN 01803077
Authority: CN
Inventors: 村濑广之
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2000-10-11
Filing date: 2001-09-27
Publication date: 2003-01-22
Anticipated expiration: 2021-09-27
Also published as: JP4094423B2; CN1233924C; WO2002031326A1; GB0217640D0; BR0107306A; JPWO2002031326A1; GB2383606B; GB2383606A; MY129022A; TW550334B; BR0107306B1; DE10194626T1

Abstract

An exhaust system of an engine having a gas purifier with a casing, to which an exhaust pipe is welded, comprises a first exhaust pipe (3) and the exhaust gas purifier (4) having a casing 20 made of first and second casing halves welded to each other. An upstream end (3b) of the first exhaust pipe 3 is connected to an exhaust manifold via a spherical joint (6) whereas a downstream end (3a) of the first exhaust pipe (3) is welded to the first casing half forming the top part of the casing (20) such that its welded joint (W1) does not overlap the welded joint (W2) between both casing halves. This configuration preventing both welded joints (W1, W2) from overlapping keeps the strength unreduced, and exhaust gas flows into the casing (20) only through the first exhaust pipe (3).

Description

Engine's exhaust system

Technical field

The present invention relates to engine's exhaust system, more particularly, relate to a kind of vent systems that comprises a catalytic converter, this catalytic converter has the housing of a welding on it one outlet pipe.

Background technique

Be used to form waste gas after burning is equipped with the catalytic converter that is used for purifying exhaust air from the conventional vent systems of the exhaust passage that engine chamber is discharged into the atmosphere, an outlet pipe that communicates with the engine emission mouth is connected on this catalytic converter.

For example, Japanese patent gazette No.11-13461 discloses a kind of technology, and an exhaust emission tube that will come out from each cylinder of a three cylinder engine is connected to one and comprises on the catalyst housing of catalyzer (corresponding to the housing of catalytic converter).This catalyst housing is cut apart casing member by two that have the flange that is welded to one another together and is formed.One exhaust output tube that comes out from first cylinder is in the welding of the joint of these casing members, and one stretches out and is welded on one of them casing member from the exhaust output tube that the 3rd cylinder is collected exhaust output tube from second cylinder.One O2 sensor fitting seat is formed on another casing member.

In the above in the routine techniques of Hui Guing, because the exhaust output tube that comes out from first cylinder is welded on the weld seam of two housings element of catalyst housing, weld seam is overlapping, and they reduce in overlapping intensity.On the other hand, the vibration transfer of motor is to exhaust output tube, and the weld seam of loading between catalyst housing and exhaust output tube that vibration produces produces a stress.Therefore a problem is arranged, because the lap that is reduced in intensity easily by the load of the vibration generation that acts on the exhaust output tube on the weld seam produces the crack.In addition, because the fitting seat that is used for the O2 sensor is soldered to the weld seam between the two housings element, a problem is arranged, the O2 sensor is limited on the position of another casing member.

Disclosure of an invention

Under these conditions, a common purpose of invention described in the claim 1 to 4 is the durability that improves the engine exhaust system with a catalytic converter, and this catalytic converter has a housing that is welded with an outlet pipe on it.A purpose of invention described in the claim 2 is to improve exhaust efficiency.A purpose of invention described in the claim 3 is to guarantee that oxygen concentration sensor is placed on big degrees of freedom is arranged on the housing.A purpose of invention described in the claim 4 is to prevent to be produced fire damage and improved sensor and the durability of catalyzer by Abgassensor.A purpose of invention is easier the outlet pipe that is positioned at the catalytic converter downstream to be connect described in the claim 5.

According to the invention described in the claim 1, a kind of engine exhaust system is provided, has a upstream exhaust pipe that allows waste gas to flow out from motor, one has the catalytic converter of a housing that is made of two case half that weld together, and one have a downstream row tracheae that is welded to the downstream on this housing, it is characterized in that: above-mentioned upstream extremity connects with above-mentioned upstream exhaust pipe by a spherical joint, above-mentioned downstream is welded on one of them case half, make its weld seam not overlapping, and above-mentioned waste gas only flow in the above-mentioned housing by above-mentioned downstream row tracheae with the weld seam of above-mentioned case half.

According to invention described in the claim 1, because being delivered to the part vibration of the motor of upstream exhaust pipe is absorbed by spherical joint by the slide relative along the sphere between upstream exhaust pipe and the downstream row tracheae, and prevent that it from arriving as only downstream row tracheae of waste gas being introduced the outlet pipe in the housing, the big loading that does not have to be produced by this vibration can prevent to occur crackle in weld seam on the weld seam between downstream row tracheae and the housing.Even when the loading that can not be passed to the downstream row tracheae by the vibration that spherical joint effectively absorbs and produce by vibration during in weld seam, not only because compare with the structure that does not have spherical joint, the vibration of being transmitted is weakened by spherical joint, and because the downstream of downstream row tracheae is not overlapping with the weld seam that connects two housings half one with the weld seam between the case half, weld seam keeps high strength, has significantly reduced the generation of crackle in the weld seam.

Therefore following effect is provided.Because being delivered to the vibration of the motor of upstream exhaust pipe is absorbed by spherical joint, even the nonabsorbable vibration transfer of spherical joint is to as waste gas being introduced the downstream row tracheae of the only outlet pipe in the housing, not only because the vibration self of being transmitted is attenuated to a certain degree by spherical joint, and because the weld seam between downstream row tracheae and the housing has high strength, significantly reduced the crackle that produces in the weld joint, the vent systems with the housing that is welded with upstream exhaust pipe on it is improved on durability.

The described invention of claim 2 is characterized in that based on the vent systems described in the claim 1, and above-mentioned housing is positioned at a height that is lower than above-mentioned upstream extremity, and above-mentioned one of them case half has constituted the top of above-mentioned housing.

Invention according to claim 2 is extended downwards because the downstream row tracheae is swum end from it, and is connected to formation and highly is lower than on first case half of case top of upstream extremity, and downtake pipe can shorten and radian reduces.

Therefore except that right requires the effect of 1 described invention, the weak point of downtake pipe and the little structure of radian can reduce flow path resistance makes the waste gas smooth discharge in the vent systems, and the raising exhaust efficiency, has simplified the layout of downstream row tracheae.

The described invention of claim 3 is based on the described engine exhaust system of claim 2, it is characterized in that catalytic converter comprises that one is received in the catalyzer in the housing, one exhaust gas entrance that leads to housing from the downstream row tracheae is positioned at the upstream of catalyzer, the upstream portion that is positioned at another above-mentioned case half of catalyzer upstream forms a fitting seat, is used to install an oxygen concentration sensor that is used to detect oxygen in waste gas.

Invention according to claim 3, oxygen concentration sensor detect the oxygen concentration of introducing the waste gas of housing from the exhaust entrance that is arranged in the catalyzer upstream in one position, catalyzer upstream.But owing to be used to install the part that the fitting seat of oxygen concentration sensor is formed at catalyzer upstream on this case half, this case half is different from the case half that is connected with the downstream exhaust gas pipe on it, and fitting seat is improved in the position narrow limitation of the catalyzer upstream portion of housing.

Therefore, also provide following effect except that right requires the effect described in 2, the fitting seat that is arranged in the case half that does not connect the downstream row tracheae has reduced the restriction on the self poisoning, for the position of oxygen concentration sensor provides bigger degrees of freedom.From the angle of its testing precision and response, optimized the selection of oxygen concentration sensor optimum position.

The described invention of claim 4 is based on the described engine exhaust system of claim 3, it is characterized in that, the weld seam that connects downstream and case half is positioned at the upstream of above-mentioned catalyzer, and an insulation cover that covers outside is fixed on the housing at a plurality of immovable points that are positioned at the catalyzer upstream.

Invention according to claim 4 owing to be provided with insulation cover in outside, can be avoided the element around housing is caused fire damage.In addition because weld seam is arranged in housing catalyzer upstream and insulation cover is fixed on the housing at a plurality of immovable points in catalyzer upstream, housing since the additional stiffness of insulation cover and between near downstream row tracheae and case half the position of weld seam improved rigidity.

Therefore except that right requires the effect of invention described in 3, also provide following effect.That is, can prevent fire damage by insulation cover around the element of housing.In addition, be positioned at the part of catalyzer upstream at housing, vibration owing to suppressing at the fixing insulation cover of a plurality of immovable points in catalyzer upstream to transmit from the downstream row tracheae can suppress the vibration of whole housing, and improve the durability that is received in the catalyzer in the housing.

Invention described in the claim 5 is based on the engine exhaust system described in the claim 1, it is characterized in that a second exhaust pipe is connected to above-mentioned housing downstream, one connecting flange is arranged on the downstream of above-mentioned second exhaust pipe, with fastener one the 3rd outlet pipe is connected on the above-mentioned second exhaust pipe, above-mentioned second exhaust pipe bending is directed to the direction that departs from above-mentioned housing axis with a straight line perpendicular to above-mentioned connecting flange conjunction plane.

Invention according to claim 5, owing to the connection plane of the second exhaust pipe connecting flange of the crooked housing axis that departs from catalytic converter is directed to a direction that departs from the housing axis, conjunction plane not can be oriented to the element that is arranged in axially towards catalytic converter towards.

Therefore, except that right requires the effect of invention described in 1, also provide following effect.Promptly, connection plane because second exhaust pipe is crooked with connecting flange is directed to the direction that departs from the housing axis, conjunction plane is not oriented is arranged in axial element towards catalytic converter towards one, when second exhaust pipe connects with the 3rd outlet pipe, even axially fuel tank is being arranged in the face of catalytic converter with a short relatively distance, also can be with the instrument that is used for fixing fastener near connecting flange, and do not interfere with this element.This is easier to fastener connecting flange and the 3rd outlet pipe be linked up, and can improve the efficient that connects second exhaust pipe and the 3rd outlet pipe.

Here in the term of Shi Yonging, term " on " and D score represent when fix in position in automobile or other vehicle and equipment direction relevant and position with engine exhaust system.Similarly, term " makes progress " and " downwards " uses with respect to the flow direction of waste gas.

The accompanying drawing summary

Fig. 1 is a plane view, has schematically shown to use the part that will be installed in the engine exhaust device on the vehicle of the present invention;

Fig. 2 is a side elevation view, schematically illustrates the part of engine exhaust device among Fig. 1;

Fig. 3 is the sectional view of a spherical joint;

Fig. 4 is the part along the catalytic converter of being got perpendicular to housing parting plane direction;

Fig. 5 is the partial sectional view of the insulation cover got along arrow V direction indication among Fig. 4;

Fig. 6 is the view along the catalytic converter housing of getting perpendicular to the direction of its parting plane;

Fig. 7 is a sectional view, and the expression outlet pipe is connected with housing;

Fig. 8 is a perspective view, the position of vent systems and fuel tank relation in the presentation graphs 1;

Fig. 9 is the planimetric map similar to Fig. 1, the position of vent systems and fuel tank relation in the presentation graphs 1; And

Figure 10 is the side view similar to Fig. 2, the position of vent systems and fuel tank relation in the presentation graphs 1.

Realize the best mode of invention

Describe referring now to 1 to 10 pair of embodiments of the invention of accompanying drawing.

At first see figures.1.and.2, Fig. 1 is a planimetric map, schematically show according to a part that is installed in a line four cylinder engine vent systems of the one embodiment of the invention in the vehicle, Fig. 2 is its side elevation view, vent systems 1 is configured for purifying exhaust air, this waste gas is the combustion gas that discharges from the firing chamber of the motor (not shown) with reciprocating piston, and it is discharged into the atmosphere, this vent systems comprises in proper order along being from upstream to downstream direction, one is connected to the exhaust manifold 2 on the engine cylinder head E, downtake pipe 3, catalytic converter 4 and second exhaust pipe 5, and comprise one the 3rd outlet pipe 40 and an auxiliary muffler 41 (Fig. 8 shows all best) that is arranged on their downstreams in Figure 10.In their downstream, vent systems also comprises, a main muffler and a tail pipe (all showing), waste gas be directed to pass the path that limits by these elements and from the tailpipe to the atmosphere in.

Exhaust manifold 2 is made up of four arms 21 to 24 and collecting pipe 2a that these arms 21 to 24 are unified into a single pipeline, and these four arms 21 to 24 are connected to relief opening along each cylinder of the axial direction alignment of engine crankshaft running shaft (direction that shows along arrow A among Fig. 1) by a cylinder head E.The downstream 2a1 of collecting pipe 2a connects with the upstream extremity 3a of downtake pipe 3 by the spherical joint that will explain in the back 6, and the downstream of downtake pipe 3 connects with the housing 20 of catalytic converter 4 simultaneously.Therefore, the exhaust manifold 2 that is positioned at spherical joint 6 upstreams forms a upstream exhaust pipe, and is positioned at the downtake pipe 3 formation one downstream outlet pipe in spherical joint 6 downstreams.

With reference to Fig. 3, spherical joint 6 comprises that one is welded to the upstream flange 7 on the collecting pipe 2a outer peripheral surface, with a downstream flange 8 that is welded on the outer peripheral surface of upstream extremity 3a of downtake pipe 3, this downtake pipe 3 by be cylindrical tube one in the double pipe structure formed of pipe 31 and one outer tube 32.Downstream flange 8 forms a spheric seat 8a, and this spheric seat 8a defines the spheric seat surface that a downstream is protruded, and upstream flange 7 forms the plane seat 7a on a qualification one plane.

Spherical joint 6 comprises a spherical liner 9, and this sphere liner 9 is used for the excircle engagement with downstream 2a1 between upstream and downstream flange 7,8.Spherical liner 9 has the spherical portion 9b that a planar surface portion 9a and who is arranged on a upstream position is arranged on position, a downstream, and this planar surface portion 9a defines a plane that contacts with plane seat 7a, and this spherical portion 9b defines a spherical that contacts with spheric seat 8a.

Upstream flange 7 forms two bolts hole 12, this two bolt hole 12 allows to insert the bolt 11 that is formed at the two through hole 10 in the downstream flange 8 and passes, thereby with a nut 14 bolt 11 is tightened and is fixed on the upstream flange 7, simultaneously a wind spring 13 around bolt 11 is compressed between bolt 11 heads and the downstream flange 8.The diameter of each through hole 10 is greater than the external diameter of bolt 11, thereby a gap is provided, and allows slide relative between spheric seat 8a and spherical portion 9b.When the vibration transfer of motor during to house steward 2, these vibrations are absorbed by the sliding movement along spherical that takes place between the spherical joint 6 spheric seat 8a of place and spherical portion 9b, therefore prevent or have suppressed to vibrate transmission to downtake pipe 3.

As shown in Figure 2, when vent systems 1 was fixed on the vehicle, the catalytic converter 4 that connects with downtake pipe 3 was positioned in a height that is lower than the upstream extremity 3a of downtake pipe 3.Catalytic converter 4 has a housing 20, contain three-way catalyst 15 in this housing 20, Nox (nitrogen oxides), the HC (hydrocarbon) and the CO (carbon monoxide) that are used for purifying exhaust air, the downstream 3b that downtake pipe 3 extends downwards from upstream extremity 3a is welded on the housing 20 at the weld seam W1 that forms thus and (sees Fig. 4 to 7).

More specifically, with reference to Figure 4 and 5, the housing of being made by sheetmetal 20 has a upstream portion 20a who is positioned at the upstream face 15a upstream of substantially cylindrical catalyzer 15, one is frustum profile and the downstream portion 20b that is positioned at the downstream substantially, and one be columniform central part 20c substantially between upstream portion 20a and downstream portion 20b on the exhaust gas flow direction, this housing 20 is by being semi-cylindrical first and second case half 21 substantially, 22 form this halves 21, the 22nd, along two segmentation (see figure 7)s of passing the parting plane P of the cylindrical basic horizontal axis of central part 20c L1.In the present embodiment, as shown in figs. 1 and 2, limited by first case half 21 owing to above water comprise most of housing 20 at housing 20 tops, first case half 21 and second case half 22 have formed upper shell half one and lower shell body half one respectively.

As shown in Figure 6, first and

second case half

21,22 are except that the downstream portion 20b of formation one groove that will be described below, circumferential edges along them has

flange

21a, 22a, and these

case half

21,22 link together by weld its

flange

21a, 22a along whole circumference.Because the flange 21a of first case half 21 is more protruding than the flange 22a of second case half 22, second case half 22 is welded to the bottom surface of the flange 21a of first case half 21 along its outer circumferential edges.Weld seam shown in Fig. 6 is represented with reference number W2.Belong to projection B1, the B2 of flange 21a of first case half, 21 upstream portion 20a and projection B3, the B4 that belongs to the flange 21a of downstream portion 20b and form four bolt hole C1 to C4 altogether, wherein per two basically with respect to the location, plane symmetry ground that comprises axis L1 and vertically across parting plane P.These bolts hole C1 to C4 holds four bolt D1 to D4 (see figure 4)s, and these four bolt D1 to D4 are fixed to an insulation cover 30 described later on the housing 20, by a slit covering shell 20 outsides.

With reference to Fig. 4 to 6, the upstream portion that first case half 21 belongs to upstream portion 20a comprises one near the part of the flange 21a upstream extremity flat substantially inclined-plane 21b that tilts of direction towards downstream, and second case half 22 belongs to the upstream portion of upstream portion 20a and comprises that one is downward-sloping and along perpendicular to the direction of the axis L1 on the parting plane P (below title " Vertical direction ") close skew back face 22c mutually from the inclined-plane 22b that tilts near the part downstream of flange 22a upstream extremity and two.

The downstream end of first and

second case half

21,22 is formed with the semi-circular recesses that is used to form matching hole, and these matching holes are used to receive the second exhaust pipe 5 that connects with the downstream end of housing 20 downstream portion 20b.The outer peripheral surface of the circumferential edges of matching hole and second exhaust pipe 5 is by linking together in their whole circumference of weld seam W3 welding.As shown in Fig. 8 to 10, one connecting flange 16 that is arranged on downstream, second exhaust pipe 5 end forms an exhaust passage in second exhaust pipe 5 downstreams, one connecting flange 42 that is arranged on the 3rd outlet pipe 40 upstream extremities that link with auxiliary tail tracheae 41 is connected with connecting flange 16 with nut 46 by three bolts 45 as fastening piece, thereby continuously second exhaust pipe 5 is connected on the 3rd outlet pipe 40.

With reference to Fig. 7, on the inclined-plane 21b of first case half 21, form a cylindrical boss portion, to limit a hole as the discharging inlet, waste gas is gone in the housing 20 by this orifice flow.The outer tube 32 of downtake pipe 3 meshes with the excircle of boss part 24, on whole circumference length they is welded, to form weld seam W1.In this case, select weld seam W1 not overlapping with the weld seam W2 of housing 20.

In the housing 20, the upstream face that inside has the catalyzer 15 of the thin air passageways that a plurality of permission waste gas therefrom flow through is positioned at the hole 23 downstream position in downstream slightly at the axial direction of the axis L1 of housing 20, and the axis L2 of the downstream 3b of downtake pipe 3 is the center of directed upstream end face 15a roughly.

As shown in Figure 5, upstream portion in second case half 22, a skew back face 22c formation one has the fitting seat 27 of jack 26, this jack 26 is used for installing therein an oxygen concentration sensor 25, and this oxygen depth transducer 25 is used for detecting the oxygen concentration as the waste gas of a characteristic of waste gas.From the viewpoint of testing precision and response, this oxygen concentration sensor 25 is fixed on the fitting seat 27, makes its detection unit occupy enough positions immediately after entering hole 23.

With reference to Figure 4 and 5, in catalytic converter 4, the insulation cover 30 that covers housing 20 outsides by a slit is made up of one first lid half one 31 and one second lid, half one 32 that link with first case half 21 and second case half 22 respectively.First lid, half one 31 covers it with the exterior contour of first case half 21, the upstream portion of first lid, half one 31 of covering shell 20 upstream portion 20a have one around be welded to downtake pipe 3 parts on the housing 20 cover this upstream portion around the 31a of portion.Have the sidepiece 31b of extension around the 31a of portion, this sidepiece 31b gradually extends lengthening from the central part of first lid, half one 31 towards the flange 21a upstream direction of first case half 21 in above-mentioned Vertical direction.First lid half one 21 the highest position of catalyzer 15 temperature in catalytic converter 4 forms a plurality of vents, and the hot air in the slit between housing 20 and the insulation cover 30 is used around catalytic converter 4 relative colder temperature replacements.Thereby avoid housing 20 overheated.Second lid, half one 32 covers them with the central part of second case half 23 and the exterior contour of downstream portion, and its downstream arrives the position near the connecting flange 16 of second exhaust pipe 5.

First and second lids, half one 31,32 has four fixing part F1 to F4 and G1 to G4 respectively, and they form four bolt hole (not shown) corresponding to four bolt hole C1 to C4 of the flange 21a of first case half 21.Among them, two the upstream fixing part F1 and the F2 of first lid, half one 31 are formed among the sidepiece 31b of these two extensions, and two fixing part F3 in downstream and F4 are formed on downstream.The upstream fixing part G1 of second lid, half one 32 and G2 are in the position that is formed on from the part that the front end upstream direction that covers second lid, half, 32 central parts is extended along flange 21a corresponding to fixing part F1 and F2, and two downstream fixing part G3 and G4 are formed on the position corresponding to fixing part F3 and F4.Like this, be sandwiched at projection B1 to B4 under the situation of fixing part G1 to G4 of the fixing part F1 to F4 of first lid, half one 31 and second lid, half one 32, bolt D1 to D4 inserts also fastening by nut H1 to H4, thereby housing 20 and insulation cover 30 are linked together.

As with fixing device bolt D1 to D4 and nut H1 to H4 fixedly among the bolt hole C1 to C4 of housing 20 standing parts of insulation cover 30, the position of upstream bolt hole C1 to C2 is positioned at the upstream of catalyzer 15 upstream face 15a as shown in Figure 7, and they are positioned at the scope S that is axially occupied by weld seam W1 along axis L1.Therefore the position of bolt hole C1 to C2 is near the weld seam W1 of downtake pipe 3 and housing 20.

With reference to Fig. 8 to 10, in the vehicle that a motor is housed, a fuel tank 43 with relative short distances with catalytic converter 4 the axial direction of housing 20 axis L1 be positioned at one with catalytic converter 4 relatively and be positioned at thereafter position.Fuel tank 43 is walked around in 40 bendings of the 3rd outlet pipe, and is connected on the auxiliary muffler 41 that is positioned at fuel tank 43 next doors.Reference number 44 expression is fixed to two supports on the car body with the 3rd outlet pipe 40.

Position sidepiece towards auxiliary muffler 41 is bent downwardly (seeing Fig. 9 and 10) to second exhaust pipe 5 slightly along a direction that departs from housing 20 axis L1 from the upstream extremity that links with catalytic converter.Therefore, the conjunction plane 16a of connecting flange 16 is oriented not towards fuel tank 43, and points to this offset direction perpendicular to the line of conjunction plane 16a.Thereby as shown in Figures 9 and 10, in this embodiment, second exhaust pipe 5 is bent to and makes the vertical lower position of conjunction plane 16a towards the auxiliary muffler 41 of a close fuel tank 43.

Therefore, when the 3rd outlet pipe 40 with connecting flange 42 is connected on the second exhaust pipe 5, can be used for instrument such as socket wrench that nut 46 is fastened on the bolt 45 are reached connecting flange 42 from fuel tank 43 bottoms with one, and do not interfere with fuel tank 43, three bolts 45 of this connecting flange 42 usefulness insertion connecting flange 16 and the nut 46 of clamping bolt 45 are connected on the connecting flange 16.

Operation and effect to embodiment with said structure describes below.

After engine start, purify by catalytic converter 4 through the waste gas of exhaust passage, be discharged in the atmosphere afterwards.The vibration transfer that is produced by the motion of motor is to vent systems 1.The partial vibration that is delivered to exhaust manifold 2 absorbs by making slide relative along the spheric seat 8a of spherical joint 6 and the spherical between the spherical portion 9b, and has avoided being delivered to the downtake pipe 3 of waste gas being introduced the outlet pipe in the housing 20 as only.Therefore the big loading that does not have to be produced by this vibration can be avoided crackle occurring in weld seam W2 on the weld seam between downtake pipe 3 and the housing 20.In addition, can not be even work as by the effectively vibrations of absorption of spherical joint 6, bigger vibration as sliding scale between the downtake pipe 3 that surpasses exhaust manifold 2 and spherical joint 6, the perhaps vibration that produces at exhaust manifold 2 downstream 2a along collecting pipe 2a flow direction axial direction, the loading that is passed to downtake pipe 3 and is produced by vibration is when weld seam, compare with the structure that does not have spherical joint 6, these vibrations have also been weakened by spherical joint 6 self, and the weld seam W1 between the downstream 3b of downtake pipe 3 and first case half 21 and with first and second case half 21 that are connected

housing

21,22 weld seam W2 is overlapping.Therefore weld seam W1 has high strength, and greatly reduces the possibility that cracks.

Guaranteed following effect thus.Promptly, because being delivered to the vibration of the motor of exhaust manifold 2 is absorbed by spherical joint 6, even spherical joint 6 nonabsorbable vibration transfer are to as waste gas being introduced the downtake pipe 3 of the only outlet pipe in the housing 20, not only because the vibration self of being transmitted is attenuated to a certain degree by spherical joint 6, and because the weld seam W1 between downtake pipe 3 and the housing 20 has high strength, significantly reduced the crackle that produces at weld seam W1 place owing to be delivered to the vibration of downtake pipe 3, the vent systems with the housing 20 that is welded with downtake pipe 3 on it is improved on durability.

Hold 3a to extend downwards because downtake pipe 3 swim from it, and be connected to formation and highly be lower than on first case half 21 at housing 20 tops of upstream extremity 3a, downtake pipe 3 can shorten and radian reduces.The weak point of the downtake pipe 3 and little structure of radian can reduce flow path resistance makes the waste gas smooth discharge in the vent systems, and improves exhaust efficiency, and has increased the effect that the layout of downtake pipe obtains simplifying.

Oxygen concentration sensor 25 detects the oxygen concentration of introducing the waste gas of housing 20 from the hole 23 that is arranged in catalyzer 15 upstreams in one position, catalyzer 15 upstreams.But owing to be used to install the part that the fitting seat 27 of oxygen concentration sensor 25 is formed at catalyzer 15 upstreams on second case half 22, these second case half, 22 differences are welded with first case half 21 of downtake pipe 3 thereon, and fitting seat 27 is improved in the position narrow limitation of catalyzer 15 upstream portion of housing 20.

Therefore, fitting seat 27 can be arranged on the case half that does not connect the downstream row tracheae, has reduced fitting seat 27 locational restrictions, for the position of oxygen concentration sensor 25 provides bigger degrees of freedom.Thereby this optimizes its testing precision for suitable placement oxygen concentration sensor 25 and response is effective.

Because being provided with insulation cover 30 covers housing 20 outsides, can avoid the element around housing 20 is caused fire damage.In addition, because weld seam is arranged in the upstream of housing 20 catalyzer 15 upstream face 15a and with bolt D1, D2 and nut H1, H2 and as bolt hole C1, the C2 of two immovable points in catalyzer 15 upstreams insulation cover 30 is fixed on the housing 20, housing 20 is improving rigidity near the position of weld seam W1 between downtake pipe 3 and first case half 21, if increased insulation cover 30 then rigidity has been arranged.In addition, because bolt hole C1, C2 are positioned at by weld seam W1 within the scope S that axis L1 direction occupies and near weld seam W1 and fitting seat 27, can weaken the vibration of transmitting from downtake pipe 3 effectively, can also prevent from effectively to be installed in that oxygen concentration sensor 25 vibrates on the fitting seat 27.

Therefore following effect is provided.Promptly, can prevent fire damage by insulation cover 30 around the element of housing 20, be positioned at the part of catalyzer 15 upstreams at housing 20, because can be by suppressing with the bolt D1, the D2 that are positioned at catalyzer 15 upstreams and the fixing insulation cover 30 of nut H1, H2 from the vibration that downtake pipe 3 transmits, can prevent housing 20 whole vibrations, and improve the durability of the catalyzer 15 that is received in the housing 20.

Downstream at the second exhaust pipe 5 that links with housing 20 is provided with connecting flange 16, be used for the 3rd outlet pipe 40 being connected to second exhaust pipe 5 with bolt 45, second exhaust pipe 5 bendings, to be directed to the direction that departs from housing 20 axis L1 perpendicular to the straight line of the connection plane 16a of connecting flange 16, the conjunction plane 16a of connecting flange that makes second exhaust pipe 5 is crooked and shell that depart from catalytic converter 4 is stopped 20 axis L1.Therefore conjunction plane 16a can be oriented not exclusively towards fuel tank 43, this fuel tank 43 is positioned in axial L1 towards catalytic converter 4.

Therefore can provide following effect.Promptly, connection plane 16a owing to second exhaust pipe 5 bendings with connecting flange 16 is directed to the direction that departs from housing 20 axis L1, conjunction plane 16a is oriented not towards fuel tank 43, this fuel tank 43 is positioned in axial L1 towards catalytic converter 4, when second exhaust pipe 5 connects with the 3rd outlet pipe 40, even with a short relatively distance fuel tank 43 is arranged in the face of catalytic converter 4 at axial L1, also can be used in nut 46 is fastened to socket wrench on the bolt 45 near connecting flange 42, and not interfere with fuel tank 43.Therefore be easier to link up, and can connect the efficient raising of second exhaust pipe 5 and the 3rd outlet pipe 40 with bolt 45 and nut 46 connecting flange 42 with connecting flange 16 and the 3rd outlet pipe 40.

The following describes the embodiment's who partly revises by the foregoing description modification structure.

Although the axis L1 with catalytic converter 4 in the previous embodiment is oriented in horizontal direction, the present invention also can be used for having the catalytic converter 4 of vertical axis.Although described downtake pipe 3 is welded direct on first housing, this embodiment is modified as the flange that downtake pipe 3 and is welded on first case half 21 and connects.Can also use three or more upstreams immovable point, rather than two, be used for insulation cover 30 is fixed to housing 20.Although described catalytic converter 4 comprises a three-way catalyst 15, catalyzer is not limited to ternary, and can be for example only to be used to purify Nox, perhaps can also use the catalytic converter 4 that does not contain catalyzer.

Although motor described in the previous embodiment is installed on the vehicle, vent systems of the present invention can be used for any motorized automobile or equipment.In addition, although in the previous embodiment second exhaust pipe bent to make connecting flange whole conjunction plane zone not towards fuel tank, but at least a portion conjunction plane is just not enough towards fuel tank, interferes to prevent the instrument and the fuel tank that are used for fixing fastener.

Claims

1. engine exhaust system, has a upstream exhaust pipe that allows waste gas to flow out from motor, one has the catalytic converter of a housing that is made of two case half that weld together, and one have a downstream row tracheae that is welded to the downstream on this housing, it is characterized in that:

Above-mentioned upstream extremity connects with above-mentioned upstream exhaust pipe by a spherical joint, above-mentioned downstream is welded on one of them case half, make its weld seam not overlapping, and above-mentioned waste gas only flow in the above-mentioned housing by above-mentioned downstream row tracheae with the weld seam of above-mentioned case half.

2. vent systems according to claim 1, wherein above-mentioned housing are positioned at a height that is lower than above-mentioned upstream extremity, and above-mentioned one of them case half has constituted the top of above-mentioned housing.

3. vent systems according to claim 2, wherein above-mentioned catalytic converter comprises that one is received in the catalyzer in the above-mentioned housing, one exhaust gas entrance that leads to above-mentioned housing from above-mentioned downstream row tracheae is positioned at the upstream of above-mentioned catalyzer, a upstream portion that is positioned at another above-mentioned case half of above-mentioned catalyzer upstream forms a fitting seat, is used to install an oxygen concentration sensor that is used to detect oxygen in waste gas.

4. engine exhaust system according to claim 3, the weld seam that wherein connects above-mentioned downstream and above-mentioned one of them case half is positioned at the upstream of above-mentioned catalyzer, and an insulation cover that covers above-mentioned outside is fixed on the above-mentioned housing at a plurality of immovable points that are positioned at above-mentioned catalyzer upstream.

5. vent systems according to claim 1, wherein a second exhaust pipe is connected to above-mentioned housing downstream, one connecting flange is arranged on the downstream of above-mentioned second exhaust pipe, with fastener one the 3rd outlet pipe is connected on the above-mentioned outlet pipe, above-mentioned second exhaust pipe bending is directed to the direction that departs from above-mentioned housing axis with a straight line perpendicular to above-mentioned connecting flange conjunction plane.