JP3248744B2 - Engine exhaust system layout structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system of an engine.

[0002]

2. Description of the Related Art Generally, in an exhaust system of an engine,
Independent exhaust passages provided for each cylinder are assembled into one exhaust passage slightly downstream of each cylinder, and a catalytic converter, a pre-silencer, a main silencer, and the like for purifying exhaust gas are interposed in this exhaust passage. The exhaust passage is mounted on the vehicle body using a plurality of mounting members.

In general, various vibrations such as a roll vibration vibrating in a circumferential direction of an output shaft or a bending vibration vibrating in a bending direction of an output shaft are caused in an engine, and these vibrations are transmitted to an independent exhaust passage or an exhaust passage. Is done. For this reason,
There is a problem that the durability or reliability of the exhaust system is reduced by such vibration, and furthermore, if this vibration is transmitted to the vehicle body via the mount member, there is a problem that unpleasant noise is generated in the vehicle.

Therefore, in order to suppress or absorb the transmission of vibration in the exhaust passage, an exhaust system in which a spherical joint (flexible joint) is provided in the exhaust passage has been proposed (for example, Japanese Utility Model Laid-Open No. 63-92023). Gazette). Such a spherical joint is provided with a seal member fixed to the upstream portion of the exhaust passage and having a convex spherical surface, and a seat portion fixed to the downstream portion of the exhaust passage and having a concave spherical surface. Are slidably in contact with each other. Therefore, the seal ring
The (upstream portion) and the seat portion (downstream portion) can be relatively displaced from each other, and the transmission of vibration from the upstream portion to the downstream portion of the exhaust passage is suppressed or absorbed by the relative displacement. In such a spherical joint, the upstream portion and the downstream portion of the exhaust passage can be relatively displaced only in the bending direction.

An exhaust system in which a universal joint (flexible tube) is provided in an exhaust passage has been proposed (for example, see Japanese Utility Model Application Laid-Open No. 61-161029). Such a universal joint is provided with a bell-shaped flexible connecting pipe connecting the upstream portion and the downstream portion of the exhaust passage, and the flexibility allows the upstream portion and the downstream portion of the exhaust passage to be displaced relative to each other. The transmission of vibration from the upstream portion to the downstream portion is suppressed or absorbed by the relative displacement. In addition, such a universal joint can be relatively displaced in all directions.

[0006]

Incidentally, in recent years, in a predetermined operating state, an engine in which the air-fuel ratio (A / F) is made leaner than the stoichiometric air-fuel ratio to improve the fuel efficiency, that is, a so-called lean burn engine has been frequently used. I have. However, such a lean burn engine has a problem in that the amount of generated NOx increases. Therefore, in a lean-burn engine, a NOx purification catalyst is usually provided in the exhaust passage, but generally, the NOx purification catalyst does not function when the exhaust gas temperature is not higher than a predetermined temperature (activation temperature). If the exhaust gas temperature is too high (for example, 700
(° C. or higher). Therefore, the exhaust passage is branched into first and second branch exhaust passages on the way, a NOx purifying catalyst is provided in the first branch exhaust passage, and a switching valve is provided in the branch portion, so that the exhaust gas temperature is within a predetermined temperature range. , An exhaust system has been proposed in which exhaust gas is passed through the first branch exhaust passage. The second
The branch exhaust passage is normally collected in the first branch exhaust passage downstream of the NOx purification catalyst.

However, in the exhaust system in which the exhaust passage is branched into the first and second branch exhaust passages, the vibration induced in the branch exhaust passage becomes very complicated, and the vibration is suppressed. There is a problem that it is difficult. For example, even if a spherical joint is provided in both branch exhaust passages to suppress this vibration, complicated vibration cannot be sufficiently suppressed or absorbed. When a universal joint is provided in both branch exhaust passages, vibration can be suppressed or absorbed, but the strength of the flexible connection pipe is relatively low, so that the flexible connection is caused by relative displacement in the bending direction. There is a problem that the pipe may be damaged. The present invention has been made in order to solve the above-mentioned conventional problems, and has a problem that the durability of a joint is reduced in an exhaust system arrangement structure of an engine in which an exhaust passage is branched on the way. An object of the present invention is to provide an engine exhaust system arrangement structure that can effectively suppress or absorb the vibration of the exhaust system without inviting.

[0008]

According to a first aspect of the present invention, there is provided an exhaust system arrangement structure for an engine, wherein (i) an exhaust passage through which exhaust gas passes is at least a part of the exhaust passage. In the exhaust system arrangement structure of the engine configured by two exhaust pipes arranged in parallel with each other,
(Ii) one of the exhaust pipes arranged in parallel,
A spherical joint is provided for connecting the upstream portion and the downstream portion of the exhaust pipe so that they can be relatively displaced in the bending direction by making spherical contact, and (iii) the other exhaust pipe has an upstream portion and a downstream portion of the exhaust pipe. The basic feature is that a universal joint is provided which connects the downstream portion with a flexible connecting pipe so as to be relatively displaceable in all directions.

In the exhaust system arrangement structure for an engine according to the first invention, the spherical joint and the universal joint are positioned such that their upstream ends are substantially equal in the extending direction of both exhaust pipes. They may be arranged in a relationship.

In the exhaust system arrangement structure for an engine according to the first invention, the spherical joint and the universal joint are arranged such that the upstream end of the spherical joint is downstream from the upstream end of the universal joint when viewed in the direction of extension of both exhaust pipes. When the catalytic converter is provided in a downstream portion of the exhaust pipe provided with the spherical joint, the catalytic converter is located at the vibration center position of the roll vibration of the exhaust pipe. It may be arranged.

The exhaust system arrangement structure for an engine according to the first invention has, in addition to the above basic features, a downstream portion of an exhaust pipe provided with a spherical joint and a downstream portion of an exhaust pipe provided with a universal joint. And a mounting member for mounting each exhaust pipe on the fixed part, respectively, so that the mounting member of the exhaust pipe provided with the spherical joint is mounted on the mounting member of the exhaust pipe provided with the universal joint. Is further arranged upstream.

An exhaust system arrangement structure for an engine according to a second aspect of the present invention has the basic features of the first aspect of the present invention, and further includes an exhaust pipe provided with a universal joint and a downstream portion of an exhaust pipe provided with a spherical joint. At the downstream portion of the pipe, a mount member for mounting each exhaust pipe on the fixed portion is provided, and the mount member of the exhaust pipe provided with the spherical joint is provided on the exhaust pipe provided with the universal joint. It is characterized in that the exhaust pipe is formed to be harder than the mount member.

According to a third aspect of the present invention, there is provided an exhaust system arrangement structure for an engine, wherein (i) an exhaust passage for passing exhaust gas is constituted by two exhaust pipes arranged in parallel at least at a part thereof. (Ii) in the bending direction by bringing the upstream part and the downstream part of the exhaust pipe into spherical contact with the first exhaust pipe of the exhaust pipes arranged in parallel. (Iii) connecting the upstream portion and the downstream portion of the exhaust pipe to the second exhaust pipe with a flexible connection pipe, so that the spherical joint is connected in all directions. A basic feature is that a universal joint is provided so as to be relatively displaceable. The exhaust system arrangement structure for an engine according to the third aspect of the present invention includes: (iv) a NOx purification catalyst interposed in the first exhaust pipe;
(V) the second exhaust pipe bypasses the NOx purification catalyst and is gathered downstream of the NOx purification catalyst on the first exhaust pipe side;
(Vi) A further feature is that a connecting member for connecting the first exhaust pipe and the second exhaust pipe is provided.

An exhaust system arrangement structure for an engine according to a fourth aspect of the present invention has the above-described basic features of the third aspect of the invention, and further includes a NOx purification catalyst interposed in the first exhaust pipe and a second exhaust pipe. Are collected on the first exhaust pipe side downstream of the NOx purification catalyst, bypassing the NOx purification catalyst, and the diameter of the first exhaust pipe is set smaller than the diameter of the second exhaust pipe. And

An exhaust system arrangement structure for an engine according to a fifth aspect of the present invention has the above-described basic features of the third aspect of the invention, and further includes a NOx purification catalyst interposed in the first exhaust pipe and a second exhaust pipe. Are collected on the first exhaust pipe side downstream of the NOx purification catalyst, bypassing the NOx purification catalyst.

According to a sixth aspect of the present invention, there is provided an exhaust system arrangement structure for an engine, wherein (i) an exhaust passage through which exhaust gas passes is constituted by two exhaust pipes arranged at least partially in parallel with each other. (Ii) connecting an upstream portion and a downstream portion of the exhaust pipe to a first exhaust pipe of the exhaust pipes arranged in parallel by a flexible connection pipe. By doing so, there is provided a universal joint which is connected so as to be capable of relative displacement in all directions, and (iii) the upstream portion and the downstream portion of the second exhaust pipe are brought into spherical contact with the second exhaust pipe in the bending direction. (Iv) a NOx purification catalyst is interposed in the first exhaust pipe, and (v) a second exhaust pipe bypasses the NOx purification catalyst. That it is gathered on the first exhaust pipe side further downstream Features.

An exhaust system arrangement structure for an engine according to a seventh aspect of the present invention has the above-described basic features of the third aspect of the invention, and further includes a NOx purification catalyst interposed in the first exhaust pipe, and a second exhaust pipe. Are located on the first exhaust pipe side downstream of the NOx purification catalyst, bypassing the NOx purification catalyst, and a position where the second exhaust pipe is more distant from the oil pan than the first exhaust pipe around the oil pan. Characterized by being arranged in

An exhaust system arranging structure for an engine according to an eighth aspect of the present invention has the above-described basic features of the third aspect of the present invention, and has an exhaust system of a spherical joint as viewed in a direction perpendicular to the extending direction of the entire exhaust system. The offset amount with respect to the position of the center of gravity and the offset amount with respect to the position of the center of gravity of the exhaust system of the universal joint are set substantially equal.

According to a ninth aspect of the present invention, there is provided an engine exhaust system arranging structure according to the eighth aspect of the present invention, wherein both exhaust pipes are gathered downstream into one common exhaust pipe. A second spherical joint is interposed in the common exhaust pipe at a portion corresponding to a vibration center position of roll vibration of the exhaust system when viewed in a direction orthogonal to a direction in which the exhaust system as a whole extends.

According to a tenth aspect, in the exhaust system arrangement structure for an engine according to the first, second, eighth, or ninth aspect, a NOx purification catalyst is interposed between the one exhaust pipe or the first exhaust pipe. Wherein the other exhaust pipe or the second exhaust pipe bypasses the NOx purification catalyst and is gathered on the one exhaust pipe or the first exhaust pipe side downstream of the NOx purification catalyst. And

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. <First Embodiment> First, a first embodiment according to the first invention, the fifth to eighth inventions, and the tenth to thirteenth inventions will be described with reference to FIGS. As shown in FIG. 7, a horizontally mounted four-cylinder engine E having first to fourth cylinders # 1 to # 4 is provided with an exhaust system H for discharging exhaust gas (combustion gas) to the outside. Have been. And this exhaust system H
Is provided with an exhaust manifold M in which first to fourth independent exhaust passages 1 to 4 for discharging exhaust gas in the first to fourth cylinders # 1 to # 4 are formed, respectively. The exhaust gas in the inside further flows into the collective exhaust pipe 5. The collective exhaust pipe 5 branches on the way into a first exhaust pipe 6 and a second exhaust pipe 7, and at the branch portion, the exhaust gas in the collective exhaust pipe 5 flows toward the first exhaust pipe 6, or A switching valve 8 that can switch whether to flow to the second exhaust pipe 7 is provided.

The first exhaust pipe 6 has a first portion near the downstream end.
A catalytic converter 9 is interposed. The first catalytic converter 9 is mainly provided with NOx (nitrogen oxide) in order from the upstream side.
NOx purification catalyst 10 that purifies (reduces)
A three-way catalyst 11 for purifying (oxidizing) (hydrocarbon) and CO (carbon monoxide) is loaded in series and separated from each other.
The downstream end of the first exhaust pipe 6 is connected to a common exhaust pipe 12, and a pre-silencer 16 (see FIG. 1) and a main silencer 17 (see FIG. 1) for reducing exhaust noise are connected to the common exhaust pipe 12. Is provided. On the other hand, a second catalytic converter 13 is provided at a portion near the upstream end of the second exhaust pipe 7, and a three-way catalyst 14 is loaded in the second catalytic converter 13. The downstream end of the second exhaust pipe 7 is connected to the first catalytic converter 9 at a position downstream of the NOx purification catalyst 10 and upstream of the three-way catalyst 11.

In this exhaust system H, basically, the exhaust gas in the collective exhaust pipe 5 flows to the first exhaust pipe 6 side,
NOx by the NOx purification catalyst 10 in the catalytic converter 9
While purifying HC and CO by the three-way catalyst 11.
And so on. However, as described above, generally, the NOx purification catalyst 10 does not function effectively unless the exhaust gas temperature is equal to or higher than a predetermined temperature (activation temperature), and if the exhaust gas temperature becomes too high (for example, 7.
(00 ° C. or higher).
Therefore, at the time of engine start when the exhaust gas temperature does not sufficiently increase, or at a predetermined operating state such as at a high load when the exhaust gas temperature becomes extremely high, the switching valve 8 is switched to change the exhaust gas in the collective exhaust pipe 5. To the second exhaust pipe 7 side, and N
The Ox purification catalyst 10 is bypassed. In this case, the exhaust gas is purified by the three-way catalyst 14 in the second catalytic converter 13 and the three-way catalyst 11 in the first catalytic converter 9.

Next, the specific structure of the exhaust system H will be described. In the following, for the sake of convenience, the vehicle longitudinal direction (FIGS. 1, 2,
In the left-right direction in FIG. 7, the vehicle front side (FIGS. 1, 2, and 7)
In Fig. 1, Fig. 2, Fig. 7, the left side is simply referred to as "front".
The right side is simply called "after." In the vehicle width direction (the horizontal direction in FIG. 3), the left side (left side in FIG. 3) when the vehicle is viewed from the front is simply referred to as “left”, and the right side (right side in FIG. 3) is simply referred to as “right”. To 1 to 3
As shown in FIG. 5, the collective exhaust pipe 5 extends almost vertically.
The first and second exhaust pipes 6 and 7 connected to the lower end of the collective exhaust pipe 5 are such that the first exhaust pipe 6 is located on the left side and the second exhaust pipe 7
Are relatively close to each other and are substantially parallel to each other. The first and second exhaust pipes 6, 7 first extend downward from the connection with the collective exhaust pipe 5, and are curved near the lower end of the engine E and immediately rightward of the oil pan 15. It passes underneath and extends almost horizontally backward. Therefore, below the engine E, the second exhaust pipe 7 is arranged at a position farther from the oil pan 15 than the first exhaust pipe 6. As described above, the exhaust gas is discharged through the second exhaust pipe 7 in an operation state in which the exhaust gas temperature is extremely high, such as at a high load, but due to the above arrangement, the second exhaust pipe 7
Thus, heat damage to the oil pan 15 can be prevented.

The diameter of the first exhaust pipe 6 is
Is set smaller than the diameter of. That is, basically, the first exhaust pipe 6 is used at a medium / low load with a relatively small amount of exhaust gas, so that the first exhaust pipe 6 has a smaller diameter than the second exhaust pipe 7 used at a high load with a large amount of exhaust gas. Because. The portion of the first exhaust pipe 6 before the first catalytic converter 9 is disposed on the left side of the center of gravity L1 of the exhaust system H, that is, the center position of the roll vibration of the exhaust system H, as viewed in the left-right direction. The exhaust pipe 7 is arranged on the right side of the center of gravity position L1. This makes it difficult for roll vibration to occur in the exhaust system H.

In a plan view, the common exhaust pipe 12 is
First, it extends substantially linearly rearward from a connection portion with the exhaust pipe 6, and a pre-silencer 16 is interposed in this portion.
The common exhaust pipe 12 is bent slightly to the left behind the pre-silencer 16 and extends almost to the left and then further to the right in order to avoid layout interference with a fuel tank (not shown) and the like. And then extend backwards again,
The main silencer 17 is connected to the rear end.
The tail pipe 1 is located behind the main silencer 17.
8 are connected. When viewed in the vertical direction, the common exhaust pipe 12 extends substantially horizontally rearward from the connection with the first exhaust pipe 6, but is slightly lifted before the main silencer 17.

The exhaust system H is mounted on a fixed part. The mounting structure of the exhaust system H will be described below. The first and second exhaust pipes 6 and 7 are fixed to the rear surface of the engine E using a first bracket 21 and are fixed to the front surface of the engine E using a second bracket 22. Further, the first and second exhaust pipes 6 and 7 are provided just in front of the first catalytic converter 9 as described later in detail, with first and second mount members provided with elastic bodies for suppressing and absorbing vibration. It is mounted on the vehicle body using 23,24. The common exhaust pipe 12 is slightly ahead of the pre-silencer 16,
It is mounted on the vehicle body using third and fourth mounting members 25 and 26 having elastic bodies for suppressing and absorbing vibration.
Further, the common exhaust pipe 12 is mounted on the vehicle body at a substantially intermediate position between the pre-silencer 16 and the main silencer 17 using a fifth mount member 27 having an elastic body for suppressing and absorbing vibration. The front end and the rear end of the main silencer 17 are respectively mounted on the vehicle body using sixth and seventh mount members 28 and 29 having elastic bodies for suppressing and absorbing vibration. With this mount structure, the exhaust system H is firmly fixed, and the transmission of vibration from the exhaust system H to the vehicle body is suppressed or absorbed.

As described above, although the temperature of the second exhaust pipe 7 becomes high, the mount member generally has relatively low heat resistance.
The mounting structure of the first and second exhaust pipes 6 and 7 is configured to prevent heat damage to the second mounting member 24.
That is, as shown in FIG. 4, the first exhaust pipe 6 and the second exhaust pipe 7 are connected by a connecting member 31 formed of a material having relatively high thermal conductivity. And this connecting member 3
The left end (the right end in FIG. 4) of the first mount member 1 is attached to the vehicle body via a support bar 32, an elastic body 33, and a mounting bar 34, which are constituent parts of the first mount member 23, respectively. In addition, the right end of the second exhaust pipe 7 or the connecting member 31 is sequentially connected to the vehicle body via a fixture 35, a support bar 36, an elastic body 37, and a mounting bar 38, which are constituent parts of the second mount member 24, respectively. Attached to. According to such a mounting structure, heat on the second exhaust pipe 7 side moves to the first exhaust pipe 6 side via the connection member 31 having high thermal conductivity. When the high-temperature exhaust gas flows, the second exhaust pipe 7 does not become so hot, and no heat damage occurs to the second mount member 24. The elastic body 33 of the first mount member 23 is
The first exhaust pipe 6 is more firmly (hardly) mounted on the vehicle body than the second exhaust pipe 7 is formed of a material harder than the elastic body 37 of the mount member 24. For this reason, the roll vibration of the first exhaust pipe 6 is strongly suppressed.

By the way, various vibrations such as roll vibration in the circumferential direction of the output shaft or bending vibration in the bending direction of the output shaft are caused in the engine E. When these vibrations are transmitted to the exhaust system H, the exhaust system H If the durability is reduced or this vibration is transmitted to the vehicle body without being sufficiently suppressed or absorbed by the mount members 23 to 29, unpleasant noise is generated inside the vehicle. Therefore, in the first embodiment, a first spherical joint 41 (flexible joint) is provided in the first exhaust pipe 6, a universal joint 42 (flexible tube) is provided in the second exhaust pipe 7, and a common exhaust pipe is provided. 12, a second spherical joint 43 (flexible joint) is provided to effectively suppress or absorb the vibration of the exhaust system H.

As shown in FIGS. 5A to 5D, the first spherical joint 41 includes a first flange 45 and a sealing member 47 fixed to the outer peripheral surface of the upstream portion 6a of the first exhaust pipe 6. , First
A second flange 46 fixed to the outer peripheral surface of the downstream portion 6b of the exhaust pipe 6 is provided. Here, the sealing member 47
The outer peripheral surface 47a has a substantially spherical convex shape.
The inner peripheral surface 46a of the flange 46 has a concave substantially spherical shape corresponding to the outer peripheral surface 47a. That is, the outer peripheral surface 47a and the inner peripheral surface 46a can be slidably contacted with each other. A plurality of rods 48 are fixedly attached to the first flange 45, and the second flange 46 is loosely fitted to these rods 48. Here, a second flange 46 is provided between the second flange 46 and each rod 48.
49 that constantly urges the first flange 45 in the direction of
The first flange 45 and the second flange 46 are urged by the spring 49 in a direction to attract each other. Due to this urging force, the outer peripheral surface 47a of the seal member 47 and the inner peripheral surface 46a of the second flange 46 are slidably in close contact with each other. Here, since the outer peripheral surface 47a and the inner peripheral surface 46a can be relatively displaced while being in close contact with each other, the upstream portion 6a and the downstream portion 6b of the first exhaust pipe 6 can be relatively displaced in the bending direction. Although not shown, the second spherical joint 43 has substantially the same configuration as the first spherical joint 41.

As shown in FIG. 6, the universal joint 42 is
A first mounting portion 50 disposed on the upstream portion 7a side of the exhaust pipe 7 and a second mounting portion 5 disposed on the downstream portion 7b side
1 and a connecting pipe 53 disposed between the first mounting portion 50 and the second mounting portion 51.
Here, the connection pipe 53 is composed of a flexible, highly airtight inner tube 53a, a bellows 53b, and a protective tube 53c having a stitch structure, and can be freely expanded and contracted or bent to some extent. I have. Then, one end of the connection pipe 53 is attached to the upstream portion 7a of the second exhaust pipe 7 by the first attachment portion 50, and the other end is attached to the downstream portion 7b by the second attachment portion 51. ing. For this reason, the upstream portion 7a and the downstream portion 7b can be displaced relative to each other in all directions.

As shown in FIGS. 1 to 3 again, since the joints 41 and 42 are interposed in both the first and second exhaust pipes 6 and 7, basically, the first and second exhaust pipes 6 and 7 are connected from the engine E to the first. , The second exhaust pipe 6,
7, the vibration transmitted to the upstream portions 6a, 7a of the downstream portion 6
The transmission to the b and 7b is suppressed or absorbed, and the vibration of the exhaust system H is effectively reduced. According to the first embodiment, in addition to such basic effects, the following effects are further obtained. Is obtained. First, since the first spherical joint 41 is interposed in the first exhaust pipe 6 and the universal joint 42 is interposed in the second exhaust pipe 7, vibration can be achieved without reducing the durability of the universal joint 42. Can be effectively suppressed. That is, the strength of the universal joint 42 is relatively low in the shear direction or the bending direction, and when the relative displacement amount in the shear direction between the upstream side and the downstream side is large, the durability is significantly reduced. However, since the first exhaust pipe 6 is provided with the first spherical joint 41 which is relatively hard to be relatively displaced (compared to the universal joint), the first spherical joint 41 allows the first and second exhaust pipes. The relative displacement of the entire joint 6 and 7 is appropriately suppressed, so that the relative displacement of the universal joint 42 in the shear direction is suppressed, and the durability of the universal joint 42 is enhanced. When spherical joints are provided in both the first and second exhaust pipes 6 and 7, relative displacement can be made only in the bending direction, so that vibration cannot be effectively suppressed. As described above, when the universal joint is interposed in both the second exhaust pipes 6 and 7, the relative displacement becomes extremely large, and the durability of the universal joint is greatly reduced as described above.

According to a layout requirement, the first spherical joint 41 is arranged so that its upstream end is located rearward of the upstream end of the universal joint 42. Accordingly, since the length of the upstream portion 6a of the first exhaust pipe 6 is longer than the length of the upstream portion 7a of the second exhaust pipe 7, the first exhaust pipe 6
The amplitude of the vertical vibration of the upstream portion 6a of the second exhaust pipe 7 becomes larger than the amplitude of the vibration of the upstream portion 7a of the second exhaust pipe 7, so that the roll vibration is easily generated in the exhaust system H. However, in the first embodiment, as described below, such roll vibration is suppressed. That is, the first
The spherical joint 41 is disposed so as to be offset to the left of the center position of the roll vibration of the exhaust system H due to the longitudinal displacement of the spherical joint 41 and the universal joint 42, that is, substantially leftward with respect to the center of gravity L1 of the exhaust system. Is offset to the right with respect to the center position of the roll vibration (exhaust system center of gravity L1), and the absolute values of the offset amounts of the joints 41 and 42 are set to be substantially equal. For this reason, the amplitudes of the vibrations of the upstream portions 6a and 7a of the first and second exhaust pipes 6 and 7 are substantially equal, and the roll vibration is less likely to occur in the exhaust system H.

As described above, since the diameter of the first exhaust pipe 6 is set relatively small, the first spherical joint 41 is reduced in size, and the outer peripheral surface 47a of the seal member 47 or the inner peripheral surface of the second flange 46 is formed. The diameter of 46a is reduced (see FIG. 5A). For this reason, the relative displacement between the upstream portion 6a and the downstream portion 6b of the first exhaust pipe 6 is facilitated, and the vibration is more effectively suppressed or absorbed. Although the exhaust gas temperature increases on the second exhaust pipe 7 side, the universal joint 42 is provided in the second exhaust pipe 7 in the first embodiment, and the universal joint 42 has a large surface area. Is cooled. Therefore, heat damage from the second exhaust pipe 7 to its surroundings is prevented.

The second spherical joint 43 is disposed at the center position of the roll vibration of the exhaust system H due to the longitudinal displacement of the spherical joint 41 and the universal joint 42, that is, substantially at the center L1 of the exhaust system. For this reason, roll vibration in the exhaust system H is more effectively suppressed.

<Second Embodiment> Hereinafter, a second embodiment according to the second invention will be described. However, since the main part of the second embodiment is common to the first embodiment, the description is omitted to avoid duplication of the description. , First
Only different points from the embodiment will be described. As shown in FIG. 8, in the second embodiment, in the positional relationship in the front-rear direction,
The first spherical joint 41 ′ is arranged so that its upstream end is located at the same position L2 as the upstream end of the universal joint 42.
According to such an arrangement, the lengths of the upstream portions 6a, 7a of the first and second exhaust pipes 6, 7 are substantially equal, so that the amplitudes of the vertical vibrations of both are substantially equal, and the first and second exhaust pipes are substantially equal. Roll vibrations as a whole 6, 7 are less likely to occur, and vibrations of the exhaust system are effectively suppressed or absorbed.

<Third Embodiment> Hereinafter, a third embodiment according to the third invention will be described. However, since the main part of the third embodiment is common to the first embodiment, the description is omitted to avoid duplication of the description. , First
Only different points from the embodiment will be described. As shown in FIG. 9, in the third embodiment, as in the first embodiment, the first spherical joint 41 has its upstream end located downstream of the upstream end of the universal joint 42 in the front-rear positional relationship. It is arranged to be. Therefore, basically, roll vibration easily occurs in the exhaust system. However, the first catalytic converter 9 is located at the center position L3 of the roll vibration of the exhaust system caused by the longitudinal displacement of the spherical joint 41 and the universal joint 42.
Since it is arranged above, roll vibration of the exhaust system is suppressed.

<Fourth Embodiment> Hereinafter, a fourth embodiment according to the fourth invention will be described. Since the main parts of the fourth embodiment are common to the first embodiment, the description will be omitted to avoid duplication of the description. , First
Only different points from the embodiment will be described. As shown in FIG. 10, in the fourth embodiment, similarly to the first embodiment, the first spherical joint 41 has its upstream end located downstream of the upstream end of the universal joint 42 in the positional relationship in the front-rear direction. It is arranged to be. Therefore, basically, roll vibration easily occurs in the exhaust system. However, the mounting member 23 ′ for mounting the first exhaust pipe 6 is different from the second exhaust pipe 7.
Is disposed on the upstream side (front side) of the second mount member 24 for mounting the first exhaust pipe 6, so that the first exhaust pipe 6 is
It is mounted harder than the exhaust pipe 7. Therefore, the amplitudes of the vibrations of the first exhaust pipe 6 and the second exhaust pipe 7 become substantially equal,
The occurrence of roll vibration in the exhaust system is reduced.

<Fifth Embodiment> A fifth embodiment according to the ninth invention will be described below. However, the main parts of the fifth embodiment are common to those of the first embodiment. , First
Only different points from the embodiment will be described. As shown in FIG. 11, in the fifth embodiment, a first spherical joint 41 ′ is provided on the second exhaust pipe 7, and a universal joint 42 ′ is provided on the first exhaust pipe 6. In general, the heat capacity of the spherical joint is considerably smaller than the heat capacity of the universal joint. Therefore, according to the fifth embodiment, the heat capacity of the second exhaust pipe 7 is reduced.
Here, when the engine is started, the exhaust gas is exhausted from the second exhaust pipe 7 side, so that the temperature of the exhaust gas is increased at the time of starting the engine, and the activity of the catalyst is quickly increased.

[0040]

According to the first invention, the following basic functions and effects can be obtained first. That is, since the joints are interposed in both the exhaust pipes, the transmission of the vibration transmitted from the engine to the upstream part of the exhaust pipe to the downstream part is suppressed or absorbed. Furthermore, a universal joint is interposed in one exhaust pipe, and a spherical joint is interposed in the other exhaust pipe, where the universal joint can be relatively displaced in all directions.
The vibration of the exhaust system is more effectively suppressed or absorbed. In addition, since the displacement of the universal joint in the shearing direction is appropriately suppressed by the spherical joint, the durability of the universal joint is enhanced, and the reliability of the exhaust system is enhanced.

In the first aspect of the present invention, if the spherical joint and the universal joint are arranged such that the upstream ends thereof are substantially at the same position, the length of the upstream portion from the joint of both exhaust pipes is substantially equal. Since they are equal, the amplitudes of the vertical vibrations in the upstream portions of both exhaust pipes are substantially equal, and the roll vibration of the exhaust system is reduced.

In the first aspect of the present invention, if the spherical joint is disposed so that its upstream end is located downstream from the upstream end of the universal joint, a catalyst is provided at a downstream portion of the exhaust pipe provided with the spherical joint. If the converter is provided, the amplitude of the vertical vibration of the upstream portion of the exhaust pipe provided with the spherical joint is larger than the amplitude of the vertical vibration of the upstream portion of the exhaust pipe provided with the universal joint. Roll vibration is more likely to occur. However, here, if the catalytic converter is arranged at the vibration center position of the roll vibration of the exhaust pipe, the roll vibration of the exhaust system is effectively reduced.

According to the first aspect, in addition to the above basic functions and effects, the following functions and effects can be further obtained. That is, when the spherical joint is arranged so that its upstream end is located downstream from the upstream end of the universal joint, basically, the vertical vibration of the upstream portion of the exhaust pipe in which the spherical joint is interposed Becomes larger than the amplitude of the vertical vibration of the upstream portion of the exhaust pipe in which the universal joint is interposed, and roll vibration is likely to occur in the exhaust system. However, according to the first aspect, the mount member of the exhaust pipe provided with the spherical joint is disposed on the front side of the mount member of the exhaust pipe provided with the universal joint, and therefore, the spherical joint is provided. Since the exhaust pipes are rigidly mounted, the amplitudes of the vertical vibrations of both the exhaust pipes are substantially equal, and the roll vibration of the exhaust system is effectively reduced.

According to the second invention, first, the same operation and effect as the above-mentioned basic operation and effect of the first invention can be obtained. And when the spherical joint is arranged so that its upstream end is located downstream from the upstream end of the universal joint,
Basically, the amplitude of the vertical vibration in the upstream portion of the exhaust pipe in which the spherical joint is interposed becomes larger than the amplitude of the vertical vibration in the upstream portion of the exhaust pipe in which the universal joint is interposed, and the roll vibration is generated in the exhaust system. According to the second aspect of the present invention, since the mount member of the exhaust pipe provided with the spherical joint mounts the exhaust pipe harder than the mount member of the exhaust pipe provided with the universal joint, the two exhausts are improved. The amplitude of the vertical vibration of the tube becomes substantially equal, and the roll vibration of the exhaust system is effectively reduced.

According to the third invention, first, the same operation and effect as the above-described basic operation and effect of the first invention can be obtained. Furthermore, since the heat on the second exhaust pipe side, which becomes hot during use, is released to the first exhaust pipe side via the connecting member, thermal deterioration of the mount member on the second exhaust pipe side is reduced.

According to the fourth invention, first, the same operation and effect as the above-mentioned basic operation and effect of the first invention can be obtained. Further, since the spherical joint is provided on the first exhaust pipe side having a small diameter, the curvature of the seal member or the seat portion of the spherical joint is reduced, and the relative displacement between the upstream portion and the downstream portion of the first exhaust pipe is reduced. It will be easier. For this reason, the vibration in the first exhaust pipe is more effectively suppressed and absorbed.

According to the fifth aspect, first, the same operation and effect as the above-described basic operation and effect of the first invention can be obtained. Further, since the universal joint having a large surface area is provided on the second exhaust pipe side where the exhaust gas temperature becomes high,
On the exhaust pipe side, the cooling of the exhaust gas is promoted, and the occurrence of heat damage to the catalyst and the like is prevented.

According to the sixth aspect, first, the same operation and effect as the above-described basic operation and effect of the first aspect can be obtained. Furthermore, since the spherical joint having a small heat capacity is arranged on the side of the second exhaust pipe used when starting the engine,
The increase in the exhaust gas temperature at the time of starting the engine is promoted, and the catalyst activity is increased early.

According to the seventh aspect, first, the same operation and effect as the above-described basic operation and effect of the first invention can be obtained. Furthermore, since the second exhaust pipe, which is heated during use, is arranged at a position far from the oil pan, it is possible to prevent the second exhaust pipe from causing heat damage in the oil pan.

According to the eighth aspect, the same operation and effect as the above-described basic operation and effect of the first invention can be obtained. Further, since the center of gravity of the exhaust system, that is, the offset amount with respect to the center of the roll vibration of the exhaust system, of the spherical joint and the universal joint is set substantially equal, the roll vibration of the exhaust system is effectively reduced.

According to the ninth aspect, basically the same functions and effects as those of the eighth aspect can be obtained. Further, since the spherical joint is provided in the common exhaust pipe at a position corresponding to the center of the roll vibration of the exhaust system, the roll vibration of the exhaust system is further effectively reduced.

According to the tenth aspect, in particular, the exhaust system in which the first exhaust pipe provided with the NOx purification catalyst and the second exhaust pipe bypassing the NOx purification catalyst are provided. The same operation and effect as in any one of the first, second, eighth, and ninth aspects can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view of an exhaust system of an engine, showing a first embodiment of the present invention.

FIG. 2 is an explanatory side view of an exhaust system of the engine shown in FIG. 1;

FIG. 3 is an elevational view of the exhaust system of the engine shown in FIG. 1 as viewed from the front side of the vehicle.

FIG. 4 is a partially sectional elevation view of a mounting structure of first and second exhaust pipes by first and second mounting members.

5A is an elevational view illustrating the spherical joint as viewed from the front side, FIG. 5B is a side sectional explanatory view of the spherical joint, FIG. 5C is a planar sectional explanatory view of the spherical joint, (d) is an elevational view as viewed from the rear side of the spherical joint.

FIG. 6 is a partially sectional side view of the universal joint.

FIG. 7 is a schematic diagram illustrating a system configuration of an engine including the exhaust system illustrated in FIG. 1;

FIG. 8 is an explanatory plan view of an exhaust system showing a second embodiment of the present invention.

FIG. 9 is an explanatory plan view of an exhaust system showing a third embodiment of the present invention.

FIG. 10 is an explanatory plan view of an exhaust system showing a fourth embodiment of the present invention.

FIG. 11 is an explanatory view of an exhaust system showing a fifth embodiment of the present invention.

[Explanation of symbols]

 E: Engine H: Exhaust system 5: Collective exhaust pipe 6: First exhaust pipe 6a: Upstream portion 6b: Downstream portion 7: Second exhaust pipe 7a: Upstream portion 7b: Downstream portion 9: First catalytic converter 10: NOx purification Catalyst 12 ... Common exhaust pipe 15 ... Oil pan 23,24 ... First and second mount members 31 ... Connecting member 41 ... First spherical joint 42 ... Universal joint 43 ... Second spherical joint 53 ... Connecting pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-92023 (JP, U) JP-A-3-73616 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 7/08 F01N 3/24 F02B 27/06 F02B 77/00

Claims (10)

(57) [Claims] An exhaust passage through which exhaust gas passes is at least partially provided in an exhaust system arrangement structure of an engine comprising two exhaust pipes arranged in parallel with each other. One of the exhaust pipes is provided with a spherical joint that connects the upstream part and the downstream part of the exhaust pipe so that they can be relatively displaced in the bending direction by making spherical contact with each other. By connecting the upstream portion and the downstream portion of the exhaust pipe with a flexible connecting pipe, a universal joint is provided that is connected so as to be relatively displaceable in all directions, and a downstream side of the exhaust pipe provided with the spherical joint is provided. A mounting member for mounting each exhaust pipe to a fixed portion is provided on each of the portion and a downstream portion of the exhaust pipe provided with the universal joint, and the mounting member of the exhaust pipe on which the spherical joint is provided is a universal joint. Is provided Exhaust system disposition structure of engine, characterized in that than square mounting member of the exhaust pipe is disposed on the upstream side. 2. An engine exhaust system in which an exhaust passage through which exhaust gas passes is constituted by two exhaust pipes arranged at least partially in parallel with each other, wherein the exhaust passages are arranged in parallel. One of the exhaust pipes is provided with a spherical joint that connects the upstream part and the downstream part of the exhaust pipe so that they can be relatively displaced in the bending direction by making spherical contact with each other. By connecting the upstream portion and the downstream portion of the exhaust pipe with a flexible connecting pipe, a universal joint is provided that is connected so as to be relatively displaceable in all directions, and a downstream side of the exhaust pipe provided with the spherical joint is provided. A mounting member for mounting each exhaust pipe to a fixed portion is provided on each of the portion and a downstream portion of the exhaust pipe provided with the universal joint, and the mounting member of the exhaust pipe on which the spherical joint is provided is a universal joint. Is provided Than Catamount member of the exhaust pipe of,
An exhaust system disposition structure for an engine, wherein the exhaust system is formed so as to rigidly mount an exhaust pipe. 3. An engine exhaust system in which an exhaust passage through which exhaust gas passes is constituted, at least in part, of two exhaust pipes arranged in parallel with each other, wherein the exhaust passage is arranged in parallel. A spherical joint is provided on the first exhaust pipe of the exhaust pipe so as to connect the upstream portion and the downstream portion of the exhaust pipe to each other so as to be relatively displaceable in the bending direction by making spherical contact. A universal joint is provided for connecting an upstream portion and a downstream portion of the exhaust pipe with a flexible connection pipe so as to be relatively displaceable in all directions, and a NOx purification catalyst is provided in the first exhaust pipe. The second exhaust pipe bypasses the NOx purification catalyst and is gathered on the first exhaust pipe side downstream of the NOx purification catalyst, and connects the first exhaust pipe and the second exhaust pipe. Characterized in that a connecting member is provided. Exhaust system mounting structure of gin. 4. An engine exhaust system in which an exhaust passage through which exhaust gas passes is constituted, at least in part, by two exhaust pipes arranged in parallel with each other, wherein the exhaust passage is arranged in parallel. A spherical joint is provided on the first exhaust pipe of the exhaust pipe so as to connect the upstream portion and the downstream portion of the exhaust pipe to each other so as to be relatively displaceable in the bending direction by making spherical contact. A universal joint is provided for connecting an upstream portion and a downstream portion of the exhaust pipe with a flexible connection pipe so as to be relatively displaceable in all directions, and a NOx purification catalyst is provided in the first exhaust pipe. The second exhaust pipe bypasses the NOx purification catalyst and is gathered on the first exhaust pipe side downstream of the NOx purification catalyst, and the diameter of the first exhaust pipe is equal to the diameter of the second exhaust pipe. Characterized in that it is set smaller than Exhaust system mounting structure of emissions. 5. An engine exhaust system in which an exhaust passage through which exhaust gas passes is constituted by two exhaust pipes arranged at least partially in parallel with each other, wherein the exhaust passages are arranged in parallel. A spherical joint is provided on the first exhaust pipe of the exhaust pipe so as to connect the upstream portion and the downstream portion of the exhaust pipe to each other so as to be relatively displaceable in the bending direction by making spherical contact. A universal joint is provided for connecting an upstream portion and a downstream portion of the exhaust pipe with a flexible connection pipe so as to be relatively displaceable in all directions, and a NOx purification catalyst is provided in the first exhaust pipe. An exhaust system arrangement structure for an engine, wherein a second exhaust pipe bypasses the NOx purification catalyst and is gathered on the first exhaust pipe side downstream of the NOx purification catalyst. 6. An engine exhaust system in which an exhaust passage for passing exhaust gas is constituted by two exhaust pipes arranged at least partially in parallel with each other, wherein the exhaust passages are arranged in parallel. A universal joint is provided on a first exhaust pipe of the exhaust pipe, the flexible pipe connecting an upstream portion and a downstream portion of the exhaust pipe with each other so as to be relatively displaceable in all directions. An upstream part and a downstream part of the second exhaust pipe,
A spherical joint is provided which is connected to the spherical surface so as to be relatively displaceable in the bending direction by contacting the spherical surface. An exhaust system arrangement structure for an engine, wherein the exhaust system is assembled on a first exhaust pipe side downstream of a purification catalyst. 7. An exhaust system arrangement structure for an engine, wherein an exhaust passage through which exhaust gas passes is at least partially provided with two exhaust pipes arranged in parallel with each other. A spherical joint is provided on the first exhaust pipe of the exhaust pipe so as to connect the upstream portion and the downstream portion of the exhaust pipe to each other so as to be relatively displaceable in the bending direction by making spherical contact. A universal joint is provided for connecting an upstream portion and a downstream portion of the exhaust pipe with a flexible connection pipe so as to be relatively displaceable in all directions, and a NOx purification catalyst is provided in the first exhaust pipe. The second exhaust pipe bypasses the NOx purification catalyst and is gathered on the first exhaust pipe side downstream of the NOx purification catalyst, and the second exhaust pipe is connected to the first exhaust pipe around the oil pan. Farther away from the oil pan than Exhaust system disposition structure of engine, characterized in that it is location. 8. An engine exhaust system in which at least a part of an exhaust passage for passing exhaust gas is constituted by two exhaust pipes arranged in parallel with each other, the exhaust passage is arranged in parallel. A spherical joint is provided on the first exhaust pipe of the exhaust pipe so as to connect the upstream portion and the downstream portion of the exhaust pipe to each other so as to be relatively displaceable in the bending direction by making spherical contact. A universal joint that connects the upstream portion and the downstream portion of the exhaust pipe with a flexible connection pipe so as to be capable of relative displacement in all directions is provided, and is perpendicular to the extension direction of the entire exhaust system. Wherein the offset amount of the spherical joint with respect to the position of the center of gravity of the exhaust system is substantially equal to the offset amount of the universal joint relative to the position of the center of gravity of the exhaust system. 9. The exhaust system arrangement structure for an engine according to claim 8, wherein both exhaust pipes are gathered downstream into one common exhaust pipe,
An engine, wherein a second spherical joint is interposed in the common exhaust pipe at a portion corresponding to a vibration center position of roll vibration of the exhaust system when viewed in a direction orthogonal to a direction in which the exhaust system as a whole extends. Exhaust system arrangement structure. 10. The exhaust system arrangement structure for an engine according to claim 1, wherein the one exhaust pipe or the first exhaust pipe is provided with a NOx purification catalyst, and the other exhaust pipe is provided with the NOx purification catalyst. An exhaust system for an engine, wherein the exhaust pipe or the second exhaust pipe bypasses the NOx purification catalyst and is gathered downstream of the NOx purification catalyst on the one exhaust pipe or the first exhaust pipe side. Arrangement structure.