JP2022143490A - Exhaust pipe joint - Google Patents

Abstract

To provide an exhaust pipe joint capable of reducing size and weight of the joint while maintaining performance of absorbing thermal deformation and sealing performance of exhaust gas.SOLUTION: An exhaust pipe joint 1820 includes: an upstream side exhaust pipe 1821 connected to an exhaust port 23 of an engine 10; a downstream exhaust pipe 1822 that overlaps in an axial direction with the upstream side exhaust pipe 1821 and is loosely fitted to the upstream exhaust pipe 1821 in a slidable manner; a first gasket 1825 and a second gasket 1826, which are arranged slidably in the axial direction in a gap between the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822 in a region where the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822 overlap with each other, to seal the gap between the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822; and a coil spring 1827 that is arranged between the first gasket 1825 and the second gasket 1826 to absorb the axial displacement of the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822.SELECTED DRAWING: Figure 4

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe joint that connects an upstream exhaust pipe and a downstream exhaust pipe that constitute an exhaust pipe for discharging exhaust gas from an engine.

2. Description of the Related Art Conventionally, among exhaust pipes for discharging exhaust gas from an engine, there has been known one in which an expandable bellows pipe (bellows pipe) is interposed in order to absorb thermal deformation (thermal expansion and contraction) of the engine.

For example, Patent Document 1 discloses a front bank exhaust pipe connected to a front bank exhaust manifold of a V-type engine that is horizontally arranged in front of a vehicle, and a rear bank exhaust pipe connecting the rear bank exhaust manifold and the front bank exhaust pipe. An exhaust pipe structure is disclosed that includes a pipe. An elastically deformable flexible pipe is attached to the front bank exhaust pipe upstream from the confluence portion where the front bank exhaust pipe joins the rear bank exhaust pipe.

The flexible tube has a structure in which a cylindrical bellows-shaped bellows is surrounded by a cylindrical cover. The bellows can be axially stretched and bent. Further, the bellows has, for example, an upstream end fixed by welding over the entire circumference of the upstream exhaust pipe that constitutes the front bank exhaust pipe, and a downstream end of the bellows that is connected to the downstream exhaust pipe constituting the front bank exhaust pipe. Welded all around.

JP 2020-159316 A

However, as described above, when the upstream exhaust pipe and the downstream exhaust pipe are covered with bellows pipes (bellows pipes) and both ends of the bellows pipes are welded and fixed over the entire circumference, mass and cost increase. Also, in order to absorb relatively large thermal deformation (thermal expansion and contraction), the size of the bellows tube (corrugated tube) is increased, which may increase the mass and cost, and reduce the degree of freedom in layout of the exhaust system. Therefore, there has been a demand to reduce the size and weight of the joint while maintaining the ability to absorb thermal deformation and the ability to seal exhaust gas.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust pipe joint capable of reducing the size and weight of the joint while maintaining the performance of absorbing thermal deformation and the sealing performance of exhaust gas.

An exhaust pipe joint according to one aspect of the present invention includes an upstream exhaust pipe having an upstream end connected to an exhaust port of an engine, and an upstream end axially overlapping the upstream exhaust pipe. a downstream side exhaust pipe slidably loosely fitted to the upstream side exhaust pipe; A gasket that is disposed slidably in a direction and seals a gap between the upstream exhaust pipe and the downstream exhaust pipe, and a gasket that seals the gap between the upstream exhaust pipe and the downstream exhaust pipe in a region where the upstream exhaust pipe and the downstream exhaust pipe overlap. An elastic member is arranged in a gap between the exhaust pipe and the side exhaust pipe so as to be axially slidable in parallel with the gasket, and absorbs axial displacement between the upstream exhaust pipe and the downstream exhaust pipe.

According to the present invention, it is possible to reduce the size and weight of the joint while maintaining the ability to absorb thermal deformation and the ability to seal exhaust gas.

It is a figure showing the whole engine composition provided with the exhaust pipe to which the exhaust pipe joint concerning an embodiment was applied. It is a figure which shows the layout (exhaust system layout) of the exhaust pipe to which the exhaust pipe joint which concerns on embodiment is applied. It is a sectional view showing composition of an exhaust pipe joint (before assembling) concerning an embodiment. FIG. 4 is a cross-sectional view showing the configuration of the exhaust pipe joint (after assembly) according to the embodiment;

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same reference numerals are used for the same or corresponding parts. Further, in each figure, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

First, an exhaust pipe joint 1820 according to an embodiment will be described with reference to FIGS. 1 to 4. FIG. FIG. 1 is a diagram showing the overall configuration of an engine 10 having an exhaust pipe 18 to which an exhaust pipe joint 1820 is applied. FIG. 2 is a diagram showing a layout (exhaust system layout) of the exhaust pipe 18 to which the exhaust pipe joint 1820 is applied. FIG. 3 is a cross-sectional view showing the configuration of exhaust pipe joint 1820 (before engine assembly). FIG. 4 is a cross-sectional view showing the configuration of exhaust pipe joint 1820 (after engine assembly).

The engine 10 is, for example, a horizontally opposed four-cylinder engine. The engine 10 is an in-cylinder injection type engine that directly injects fuel into a cylinder (inside a cylinder). In the engine 10, air taken in from an air cleaner 16 is throttled by an electronically controlled throttle valve (hereinafter simply referred to as a "throttle valve") 13 provided in an intake pipe 15, passes through an intake manifold 11, and enters the engine 10. It is sucked into each formed cylinder. Here, the amount of air sucked from the air cleaner 16 is detected by an air flow meter 14 arranged between the air cleaner 16 and the throttle valve 13 . A vacuum sensor 30 that detects the pressure in the intake manifold 11 (intake manifold pressure) is arranged inside the collector portion (surge tank) that constitutes the intake manifold 11 . Further, the throttle valve 13 is provided with a throttle opening sensor 31 for detecting the opening of the throttle valve 13 .

The cylinder head is formed with an intake port 22 and an exhaust port 23 for each cylinder (only one bank is shown in FIG. 1). Each of the intake port 22 and the exhaust port 23 is provided with an intake valve 24 and an exhaust valve 25 for opening and closing the intake port 22 and the exhaust port 23 .

Each cylinder of the engine 10 is equipped with an injector 12 that injects fuel into the cylinder. The injector 12 directly injects fuel pressurized by a high-pressure fuel pump (not shown) into the combustion chamber of each cylinder.

An ignition plug 17 for igniting the air-fuel mixture and an igniter built-in coil 21 for applying a high voltage to the ignition plug 17 are attached to the cylinder head of each cylinder. In each cylinder of the engine 10, a mixture of intake air and fuel injected by the injector 12 is ignited by the ignition plug 17 and burned. Exhaust gas after combustion is discharged through an exhaust pipe 18 .

In the exhaust pipe 18, a part of the exhaust gas discharged from the engine 10 is recirculated (recirculated) to the intake manifold 11 (intake system) of the engine 10. An exhaust gas recirculation device (hereinafter referred to as "EGR (Exhaust Gas Recirculation) device") 40 is provided. The EGR device 40 is installed on the EGR pipe 41 that communicates between the exhaust pipe 18 (downstream of the collecting portion 185) of the engine 10 and the intake manifold 11, and on the EGR pipe 41, and controls the exhaust gas recirculation amount (EGR amount). It has an EGR valve 42 to regulate.

The opening degree of the EGR valve 42 is controlled (duty control) by an electronic control unit (hereinafter referred to as “ECU”) 50 . That is, the ECU 50 controls the recirculation amount (recirculation amount) of the exhaust gas by adjusting the opening/closing amount of the EGR valve 42 according to the operating state of the engine 10 . The EGR valve 42 may be of a negative pressure type or of a type driven by a stepping motor or the like.

Here, the layout of the exhaust system of the engine 10 will be described with reference to FIG. 2 as well. A #1 exhaust pipe 181 is connected to the exhaust port 23 of the #1 cylinder. A #2 exhaust pipe 182 is connected to the exhaust port 23 of the #2 cylinder. Similarly, a #3 exhaust pipe 183 is connected to the exhaust port 23 of the #3 cylinder, and a #4 exhaust pipe 184 is connected to the exhaust port 23 of the #4 cylinder. Here, the firing order (ignition order) of the engine 10 is the first cylinder (#1) - the third cylinder (#3) - the second cylinder (#2) - the fourth cylinder (#4). Exhaust gas from each cylinder is discharged to respective exhaust pipes 181 to 184 every 180° CA.

Also, the #1 exhaust pipe 181 and the #2 exhaust pipe 182 are put together, and the #3 exhaust pipe 183 and the #4 exhaust pipe 184 are put together. Then, both are further assembled on the downstream side (collecting section 185). That is, the four #1 to #4 exhaust pipes 181 to 184 attached to each cylinder (#1 cylinder to #4 cylinder) of the engine 10 are gathered together at the gathering portion 185 . A collective exhaust pipe 186 is connected to the collective portion 185 .

An exhaust purification catalyst (catalyzer) 20 is interposed in the collective exhaust pipe 186 (downstream of the collective portion 185). Here, the exhaust purification catalyst 20 is a three-way catalyst, which oxidizes hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas and reduces nitrogen oxides (NOx) at the same time. It purifies harmful gas components into harmless carbon dioxide (CO ₂ ), water vapor (H ₂ O) and nitrogen (N ₂ ).

Between the collecting portion 185 of the exhaust pipe 18 and the connection hole of the EGR pipe 41 (upstream side of the exhaust purification catalyst 20), a signal corresponding to the oxygen concentration and the unburned gas concentration in the exhaust gas is output (that is, An air-fuel ratio sensor 19 for detecting the air-fuel ratio of the air-fuel mixture is attached. As the air-fuel ratio sensor 19, a linear air-fuel ratio sensor (LAF sensor) capable of linearly detecting the air-fuel ratio is used.

For example, a #2 exhaust pipe 182 and a #4 exhaust pipe 184 connected (fastened) to the left bank (LH head) of the engine 10 are provided with heat exhaust pipes that mainly absorb thermal deformation (thermal expansion and contraction) of the engine 10 in the left-right direction. A fitting 1820 is interposed. Since the exhaust pipe joint 1820 of the #2 exhaust pipe 182 and the exhaust pipe joint 1820 of the #4 exhaust pipe 184 have the same configuration, the exhaust pipe joint 1820 of the #2 exhaust pipe 182 will be described here as an example. do.

The #2 exhaust pipe 182 mainly has an upstream exhaust pipe 1821, a downstream exhaust pipe 1822, and an exhaust pipe joint 1820 that telescopically connects the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822. It is configured.

The upstream end of the upstream exhaust pipe 1821 is connected to the exhaust port 23 (corresponding to the exhaust port) of the engine 10 .

As shown in FIGS. 3 and 4 , the downstream exhaust pipe 1822 axially overlaps (overlaps) the upstream exhaust pipe 1821 at its upstream end and slides on the upstream exhaust pipe 1821 . It is loosely fitted so as to be movable (slidable). In this embodiment, the diameter of the downstream side exhaust pipe 1822 at the overlapping portion 1823 is set larger than the diameter of the upstream side exhaust pipe 1821 so that the downstream side exhaust pipe 1822 covers the upstream side exhaust pipe 1821 .

The exhaust pipe joint 1820 mainly includes gaskets 1825 and 1826 and a coil spring 1827 .

The gaskets 1825 and 1826 are axially divided into a first gasket 1825 located on the upstream side and a second gasket 1826 located on the downstream side. Each of the first gasket 1825 and the second gasket 1826 is formed in a substantially cylindrical shape (tubular shape), and in an overlap region (overlap portion 1823) where the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 overlap each other, It is arranged slidably (slidably) in the axial direction in an annular gap defined by the exhaust pipe 1821 and the downstream exhaust pipe 1822 .

The first gasket 1825 and the second gasket 1826 seal an annular gap between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 so that exhaust gas does not leak from the exhaust pipe joint 1820 . That is, the first gasket 1825 and the second gasket 1826 maintain airtightness between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 . The first gasket 1825 and the second gasket 1826 are preferably made of heat-resistant stainless steel (eg, SUS310S) or the like that can withstand the high temperature of the exhaust gas and maintain its elasticity.

The coil spring 1827 (corresponding to the elastic member described in the claims) is arranged in an overlapping region (overlapping portion 1823) where the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 overlap each other. and the downstream side exhaust pipe 1822 so as to be slidable (slidable) in the axial direction. The coil spring 1827 is arranged side by side with the first gasket 1825 and the second gasket 1826 . In this embodiment, coil spring 127 is positioned between first gasket 1825 and second gasket 1826 .

The coil spring 1827 absorbs axial displacement (relative displacement) between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 due to thermal deformation (thermal expansion and contraction) of the engine 10 or the like. The coil spring 1827 is preferably made of heat-resistant stainless steel (for example, SUS310S) or the like that can withstand the high temperature of the exhaust gas and maintain its elasticity.

As described above, since the first gasket 1825, the second gasket 1826, and the coil spring 1827 are formed and arranged, one (upstream) end of the first gasket 1825 is located on the upstream side of the downstream exhaust pipe 1822. It abuts on the inner surface of the end (tapered portion). The other (downstream) end of the first gasket 1825 contacts one (upstream) end of the coil spring 1827 . One (upstream) end of the second gasket 1826 contacts the other (downstream) end of the coil spring 1827 . The other (downstream) end of the second gasket 1826 contacts the outer surface of the downstream end (tapered portion) of the upstream exhaust pipe 1821 .

More specifically, the downstream end (opening) of the upstream exhaust pipe 1821 is tapered to expand outward. On the other hand, the upstream end (opening) of the downstream exhaust pipe 1822 is formed in a tapered shape so as to be narrowed inward.

The first gasket 1825 has one (upstream) end formed in a wedge shape along the tapered surface of the tapered portion of the downstream exhaust pipe 1822 when viewed in cross section along the axial direction. That is, one (upstream) end is cut at the same angle as the taper angle of the tapered portion so as to face the tapered surface (inner surface) of the tapered portion of the downstream exhaust pipe 1822 . In addition, the first gasket 1825 protrudes (curves) radially inward in an arc shape so that the axial center portion contacts the outer peripheral surface of the upstream exhaust pipe 1821 when viewed in cross section along the axial direction. is doing.

Similarly, the second gasket 1826 has a wedge shape along the tapered surface of the tapered portion of the upstream exhaust pipe 1821 at the other (downstream) end when viewed in cross section along the axial direction. . That is, the other (downstream) end is cut at the same angle as the taper angle of the tapered portion so as to face the tapered surface (outer surface) of the tapered portion of the upstream exhaust pipe 1821 . When viewed in cross section along the axial direction, the second gasket 1826 protrudes (curves) radially outward in an arc shape so that the central portion in the axial direction contacts the inner peripheral surface of the downstream side exhaust pipe 1822 . )is doing.

As shown in FIG. 4, exhaust pipe joint 1820 is assembled to engine 10 with coil spring 1827 being appropriately compressed. Therefore, when the #2 exhaust pipe 182 is assembled to the engine 10 , the coil spring 1827 prevents the first gasket 1825 and the second gasket 1826 from overlapping the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 . A biasing force is applied in the direction (axial direction) in which the

With the configuration as described above, the gap between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 in the region where the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 overlap (overlap portion 1823) A gap between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 is sealed by disposing the first gasket 1825 and the second gasket 1826 so as to be slidable in the axial direction.

In addition, in a region where the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 overlap (overlapping portion 1823), a coil spring is slidably inserted in the gap between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 in the axial direction. Axial displacement (relative displacement) between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 is absorbed by the provision of 1827 . Therefore, it becomes unnecessary to use a bellows tube (bellows tube).

As described in detail above, according to the present embodiment, the exhaust pipe joint 1820 can be reduced in size and weight because it is not necessary to use a bellows pipe. Moreover, since welding of a bellows pipe (bellows pipe) is not required, the weight of the exhaust pipe joint 1820 can be reduced. On the other hand, in the region where the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822 overlap, a first gasket 1825 and a second gasket are slidably inserted in the axial direction in the gap between the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822 . Since 1826 is provided, the gap between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 can be sealed. A coil spring 1827 is arranged axially slidably in a gap between the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822 in a region where the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822 overlap each other. Therefore, axial displacement (relative displacement) between the upstream exhaust pipe 1821 and the downstream exhaust pipe 1822 can be absorbed. As a result, according to the present embodiment, it is possible to reduce the size and weight of the joint while maintaining the ability to absorb thermal deformation and the ability to seal exhaust gas.

Further, according to the present embodiment, the downstream end (opening) of the upstream exhaust pipe 1821 is tapered so as to expand outward, and the upstream end (opening) of the downstream exhaust pipe 1822 is tapered. part) is formed in a tapered shape so as to be squeezed inward. One (upstream) end of the first gasket 1825 is formed in a wedge shape along the tapered surface of the tapered portion of the downstream exhaust pipe 1822, and the other (downstream) end of the second gasket 1826 is formed upstream. It is formed in a wedge shape along the tapered surface of the tapered portion of the side exhaust pipe 1821 . In addition, the axial central portion of the first gasket 1825 protrudes (curves) radially inward in an arc so as to contact the outer peripheral surface of the upstream exhaust pipe 1821, and the axial central portion of the second gasket 1826 extends downstream. It protrudes (curves) radially outward in an arc shape so as to come into contact with the inner peripheral surface of the side exhaust pipe 1822 . Therefore, it is possible to improve the performance of absorbing thermal deformation and the performance of sealing exhaust gas.

In particular, according to this embodiment, the exhaust pipe joint 1820 is assembled to the engine 10 with the coil spring 1827 being appropriately compressed. Therefore, thermal deformation in the axial direction (lateral direction) can be absorbed within the range of elastic deformation of the coil spring 1827 . Also, the coil spring 1827 applies a biasing force to the first gasket 1825 and the second gasket 1826 in a direction (axial direction) that widens the overlap between the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822 . Therefore, the ends of the first gasket 1825 and the second gasket 1826 are pressed against the tapered portions of the upstream side exhaust pipe 1821 and the downstream side exhaust pipe 1822, respectively, and are bent within the range of elastic deformation to form curved portions (contact portions). A surface pressure is generated at the , and the sealing performance can be exhibited.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiment, the case where the present invention is applied to the horizontally opposed engine 10 has been described as an example, but the present invention can also be applied to, for example, a V-type engine or an in-line engine. . Furthermore, the number of cylinders of the engine is not limited to 4 cylinders, and can be applied to engines having 6 cylinders, 8 cylinders, or more cylinders, for example.

In the above-described embodiment, the exhaust pipe joint 1820 is applied to the #2 exhaust pipe 182 and the #4 exhaust pipe 184 connected to the left bank (LH head) of the engine 10. It may be applied to the connected #1 exhaust pipe 181 and #3 exhaust pipe 183 .

In the above embodiment, the diameter of the downstream side exhaust pipe 1822 at the overlapping portion 1823 is set larger than the diameter of the upstream side exhaust pipe 1821, and the downstream side exhaust pipe 1822 covers the upstream side exhaust pipe 1821. Conversely, the diameter of the upstream exhaust pipe 1821 may be set larger than the diameter of the downstream exhaust pipe 1822 so that the upstream exhaust pipe 1821 covers the downstream exhaust pipe 1822 .

In the above embodiment, the gasket is divided into the first gasket 1825 and the second gasket 1826, but the gasket may be an integral type (it does not have to be divided into two). A coil spring 1827 is then placed at one end of the gasket.

In the above embodiment, the downstream end of the upstream exhaust pipe 1821 is tapered so as to expand outward, and the upstream end of the downstream exhaust pipe 1822 is tapered inward. However, for example, the downstream end of the upstream exhaust pipe 1821 may be bent outward at right angles, and the upstream end of the downstream exhaust pipe 1822 may be bent inward at right angles.

In the above embodiment, the coil spring 1827 is made of heat-resistant stainless steel (eg, SUS310S), but heat-resistant rubber or the like may be used, for example.

10 engine 11 intake manifold 18 exhaust pipe 181 #1 exhaust pipe 182 #2 exhaust pipe 1820 exhaust pipe joint 1821 upstream exhaust pipe 1822 downstream exhaust pipe 1823 overlap portion 1825, 1826 gaskets (first gasket, second gasket)
1827 coil spring 183 #3 exhaust pipe 184 #4 exhaust pipe 185 collective portion 186 collective exhaust pipe 19 air-fuel ratio sensor 20 exhaust purification catalyst 22 intake port 23 exhaust port

Claims (5)

an upstream exhaust pipe having an upstream end connected to an exhaust port of the engine;
a downstream exhaust pipe whose upstream end axially overlaps the upstream exhaust pipe and is slidably and loosely fitted in the upstream exhaust pipe;
In a region where the upstream side exhaust pipe and the downstream side exhaust pipe overlap, it is disposed axially slidably in a gap between the upstream side exhaust pipe and the downstream side exhaust pipe, and the upstream side exhaust pipe and the a gasket that seals a gap with the downstream side exhaust pipe;
In a region where the upstream side exhaust pipe and the downstream side exhaust pipe overlap, the gasket is arranged in a gap between the upstream side exhaust pipe and the downstream side exhaust pipe so as to be axially slidable, and an elastic member that absorbs axial displacement between the side exhaust pipe and the downstream exhaust pipe. The gasket comprises a first gasket and a second gasket divided along the axial direction,
2. The exhaust pipe joint according to claim 1, wherein the elastic member is arranged between the first gasket and the second gasket. The upstream exhaust pipe has a tapered downstream end,
3. The exhaust pipe joint according to claim 2, wherein the downstream side exhaust pipe has a tapered upstream end. The first gasket has an end portion formed in a wedge shape along the tapered surface of the tapered portion of the downstream side exhaust pipe, and an axial central portion protruding in an arc shape in the radial direction so as to contact the upstream side exhaust pipe. ,
The second gasket has an end portion formed in a wedge shape along the tapered surface of the tapered portion of the upstream side exhaust pipe, and an axial central portion protruding in an arc shape in the radial direction so as to contact the downstream side exhaust pipe. 4. The exhaust pipe joint according to claim 3, characterized in that The elastic member applies an urging force to the gasket in a direction to widen an overlap between the upstream exhaust pipe and the downstream exhaust pipe when the exhaust pipe is assembled to the engine. The exhaust pipe joint according to any one of claims 1 to 4.

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