JP2010270636A - Exhaust pipe structure of internal combustion engine and output adjusting method for the internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust pipe structure of an internal combustion engine, capable of easily adjusting output in a simple structure, in an exhaust system of the internal combustion engine. <P>SOLUTION: This exhaust pipe structure of the internal combustion engine includes a substantially cylindrical outer pipe 11 constituting an exhaust flow passage A of the internal combustion engine (engine (e)), and an inner pipe 12 detachably provided in a halfway in the outer pipe 11 and having an axial center coincident with the axial center of the outer pipe 11. The inner pipe 12 has a tapered part 12c wherein the outer peripheral end on an upstream side of the exhaust flow passage A is abutted on the inner wall of the outer pipe 11 throughout the total circumference, and the diameter is gradually reduced toward the downstream side of the exhaust flow passage A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust pipe structure of an internal combustion engine such as an automobile engine and an output adjustment method of the internal combustion engine, and more particularly, in the middle of a substantially cylindrical outer pipe constituting the exhaust flow path, on the downstream side of the exhaust flow path. The present invention relates to an engine that is provided with an inner pipe having a tapered portion that gradually decreases in diameter and optimizes engine characteristics related to exhaust efficiency.

  For example, in an automobile engine that is a typical internal combustion engine, engine characteristics such as maximum output at high speed or torque with respect to the number of revolutions vary depending on the type of vehicle or purpose of use of the automobile. One of the parameters for adjusting the engine characteristics is optimization of the exhaust passage.

  The optimization of the exhaust flow path is performed by adjusting the structure of the exhaust pipe and the silencer (muffler) that become the exhaust flow path. Conventionally, for example, in the exhaust pipe, the front pipe (exhaust manifold and catalyst) For the silencer, adjust the shape (exhaust pipe connecting the pipe to the pipe) (inner diameter and length of pipe, cross-sectional shape, handling, etc.), and the silencer has a double cylindrical structure inside, and the cross-sectional area of the inner and outer pipes The ratio and the length ratio were adjusted and the optimization was performed (for example, refer to FIG. 1 of Patent Document 1).

JP-A-8-74557

  However, in adjusting engine characteristics by optimizing the exhaust flow path, it is difficult to design analytically because it involves both intake and combustion in an internal combustion engine. The entire front pipe) and silencer, etc. are prepared, and the optimal shape is selected by trial and error. Adjustment of the engine characteristics by such optimization of the exhaust flow path requires a great deal of time and effort. There was a problem that it took time.

  The present invention has been made to solve the above-described problems.

  The invention according to claim 1 has a substantially cylindrical outer pipe that constitutes an exhaust passage of the internal combustion engine, and an axial core that is detachably provided in the middle of the outer pipe and that coincides with the axial core of the outer pipe. The inner pipe and the inner pipe have a taper whose outer peripheral edge on the upstream side of the exhaust flow path contacts the inner wall of the outer pipe over the entire circumference and gradually decreases in diameter toward the downstream side of the exhaust flow path. 1 is an exhaust pipe structure of an internal combustion engine having a portion.

  According to a second aspect of the present invention, in the exhaust pipe structure of the internal combustion engine according to the first aspect, a flexible bellows-like joint is provided in the middle of the outer pipe, and the inner pipe is the bellows-like shape in the outer pipe. It is located in the site | part covering the substantially full length of the flow path direction of this joint.

  According to a third aspect of the present invention, in the middle of the substantially cylindrical outer pipe that constitutes the exhaust passage of the internal combustion engine, an inner pipe having an axis that coincides with the axis of the outer pipe is detachably provided. The pipe has a tapered portion whose outer peripheral edge on the upstream side of the exhaust flow path contacts the inner wall of the outer pipe over the entire circumference and gradually decreases in diameter toward the downstream side of the exhaust flow path. An output adjustment method for an internal combustion engine that adjusts output characteristics of the internal combustion engine by changing a ratio of a flow passage area at an end portion on the downstream side of the tapered portion and a flow passage area at an end portion on the upstream side of the tapered portion It is.

  According to the exhaust pipe structure of the internal combustion engine according to claim 1, an inner pipe that is detachably provided in the middle of the outer pipe and has an axis that matches the axis of the outer pipe, and the inner pipe Since the outer peripheral edge on the upstream side of the flow path is in contact with the inner wall of the outer pipe over the entire circumference and has a tapered portion that gradually decreases in diameter toward the downstream side of the exhaust flow path, the exhaust gas can be configured with a simple configuration. The discharge speed can be increased, and the output speed of the internal combustion engine related to the exhaust efficiency can be easily optimized by adjusting the discharge speed by inertia action.

  According to the second aspect of the present invention, in addition to the effect of the exhaust pipe structure of the internal combustion engine according to the first aspect, the inner pipe is located in a portion of the outer pipe that extends over substantially the entire length in the flow path direction of the bellows-like joint. Therefore, it is possible to prevent exhaust gas from directly hitting the bellows-like joint and increase the flow resistance, and to prevent a reduction in exhaust efficiency even with an exhaust pipe structure provided with a bellows-like joint. In addition, since the exhaust gas does not directly hit the bellows-like joint, deterioration of the joint due to overheating can be prevented.

  According to the output adjustment method for an internal combustion engine according to claim 3, the inner pipe having an axial center that coincides with the axial center of the outer pipe in the middle of the substantially cylindrical outer pipe constituting the exhaust passage of the internal combustion engine. The inner pipe has an outer peripheral edge on the upstream side of the exhaust flow path that contacts the inner wall of the outer pipe over the entire circumference and gradually decreases in diameter toward the downstream side of the exhaust flow path. And changing the ratio of the flow area at the downstream end of the taper and the flow area at the upstream end of the taper to change the output characteristics of the internal combustion engine. Therefore, the exhaust gas discharge speed can be changed with a simple configuration, and the output speed of the internal combustion engine related to the exhaust efficiency can be easily optimized by adjusting the discharge speed by the inertial action.

FIG. 1 is a schematic cross-sectional view showing a main part of an exhaust pipe structure of an internal combustion engine according to a first embodiment of the present invention, in which FIG. The figure cut | disconnected by the XX line of Fig.1 (a) is each shown. It is the schematic which showed arrangement | positioning of the flux adjustment part of FIG. 1 in an exhaust flow path. FIG. 3 is a schematic cross-sectional view in which the inner diameter of the downstream opening of the inner pipe in FIG. 1 is variously changed, FIG. 3 (a) shows an inner diameter L2, FIG. 3 (b) shows an inner diameter L2 ′, and FIG. (C) shows an inner diameter L2 ″. It is the figure which showed the test result of FIG. It is the figure which showed the test result of FIG. It is the schematic sectional drawing which showed the modification of the inner tube | pipe of FIG. It is the schematic which showed the exhaust pipe structure of the internal combustion engine which concerns on 2nd Example of this invention. 8A and 8B are schematic cross-sectional views showing the main part of the exhaust pipe structure of the internal combustion engine of FIG. 7, in which FIG. 8A is a view in the direction of the exhaust flow path, and FIG. 8B is Y in FIG. The figure cut | disconnected by the -Y line | wire is shown, respectively. It is the schematic which showed the modification of FIG.

  A first embodiment of the present invention will be described with reference to FIGS. In the following embodiment, an automobile engine is exemplified as the internal combustion engine. FIG. 1A shows a flux adjusting unit 10 that is a main part of the present invention. The flux adjusting unit 10 is roughly provided in an outer tube 11 and the outer tube 11. The inner tube 12 is configured.

  In FIG. 2, A indicates an exhaust passage, and the exhaust passage A is connected to an exhaust port of a cylinder head of an engine e of, for example, a multi-cylinder (a four-cylinder engine e is illustrated in FIG. 2). An exhaust manifold m for joining the exhaust gas from the engine e, a front pipe 1 connected to the exhaust manifold m, a catalyst device 2 connected to the front pipe 1 for purifying exhaust gas, and the catalyst device 2, an intermediate pipe 3 connected to the intermediate pipe 3, a silencer 4 that silences the pulsation noise of the engine e, and a tail pipe 5 that is connected to the silencer 4 and discharges exhaust gas to the outside of the vehicle. Therefore, the above-described flux adjusting unit 10 is provided in the middle of the front pipe 1 as shown in FIG.

  In the above-described flux adjusting unit 10, the outer tube 11 constitutes the exhaust flow path A of the engine e, and is formed of a substantially cylindrical metal material. As shown in FIG. 1, the outer tube 11 is provided with flanges 13 and 13 for attaching an inner tube 12 to be described later.

  The inner pipe 12 is provided in the middle of the outer pipe 11 and has an axis that matches the axis of the outer pipe 11, and the outer peripheral edge on the upstream side of the exhaust passage A extends over the entire circumference of the outer pipe 11. And a tapered portion 12c that gradually decreases in diameter toward the downstream side of the exhaust passage A. That is, the channel area S2 at the downstream end of the tapered portion 12c is formed to be smaller than the channel area S1 at the upstream end of the tapered portion 12c (S2 <S1).

  The inner tube 12 is made of a metal material and is detachably provided on the outer tube 11. As shown in FIGS. 1 and 3, an opening 12a on the upstream side of the inner tube 12 is provided. , A flange 12d projecting in a direction perpendicular to the axial direction is provided, the flange 12d is sandwiched between the flanges 13 and 13, and a plurality of through holes 13a formed in the flange 13 are provided. A bolt 14 is inserted into each of 13a (in this embodiment, six through holes 13a are illustrated as shown in FIG. 1B). They are fastened to each other and fixed to the outer tube 11. It should be noted that the inner pipe 12 is removed by removing the bolts 14 and nuts 15 and releasing the clamping to the flange 13. Moreover, in FIG. 1, 16 has shown the packing which keeps airtightness and prevents the leakage of exhaust gas.

  By the way, it is preferable that the inner diameter of the opening 12a is formed so as to be the same as the inner diameter of the outer tube 11 so that no step is generated at the connecting portion between the outer tube 11 and the inner tube 12.

  FIG. 3 shows various inner pipes 12 for selection. For example, FIG. 12 (a) shows a comparatively wide downstream end of the tapered portion 12c (L2), and FIG. 12 (c). Is the one where the downstream end of the taper portion 12c is relatively narrow (L2 ″), and FIG. 12B is the intermediate end of the taper portion 12c between FIG. 12A and FIG. 12C. (L2 ') is shown respectively (L2> L2'> L2 "). The inner diameter L1 (same as the opening diameter of the opening 12a) of the upstream end of the tapered portion 12c is the same, and the same inner diameter as the inner diameter of the outer tube 11. By selecting and attaching a suitable one from these various inner pipes 12, it is possible to easily obtain optimum engine characteristics (engine output, torque, etc.) in accordance with the vehicle type and the purpose of use of the automobile.

  Next, the effect of the exhaust pipe structure of the internal combustion engine according to the first embodiment configured as described above will be described with reference to FIGS. FIG. 4 shows the engine output with respect to the engine speed, and FIG. 5 shows the torque with respect to the engine speed.

[Example 1]
・ Engine: BP-RS type 1839cc / 4 cylinder gasoline fuel manufactured by Mazda ・ Outer pipe: Inner diameter φ57.0mm
・ Inner tube: Inner diameter φ57.0mm at the upstream end of the taper
Inner diameter φ42.5mm at the downstream end of the taper
Taper length 120mm
Mounting part is in the middle of the front pipe [Example 2]
The configuration is the same as that of Example 1 except that the inner diameter of the downstream end of the tapered portion of the inner tube is φ47.5 mm.
[Comparative Example 1]
The configuration is the same as that of the first embodiment except that no inner pipe is provided.

(Measuring method)
Engine output and torque were measured using the following measuring device.
Electric dynamometer, manufactured by Tokyo Plant Co., Ltd. Model: EDH-440

  As shown in FIGS. 4 and 5, both the engine output and torque of Examples 1 and 2 having the inner pipe are compared with those of Comparative Example 1 in which the inner pipe is not provided. Min) High values could be obtained throughout. Particularly in the engine output, those provided with an inner pipe tend to further increase even when the speed exceeds 6000 rpm, and the value is the inner diameter of the downstream end of the tapered portion, that is, exhaust gas discharge. It was different depending on the speed.

  By the way, as shown in FIG. 6, the rectification part 12e which expands continuously and gradually toward the downstream side from the downstream end part of the taper part 12c is formed in the opening part 12b on the downstream side of the inner pipe 12 described above. You may make it form. The rectifying unit 12e suppresses the flow of the exhaust gas passing through the opening 12b from becoming turbulent in the opening 12b, reduces the pressure loss of the exhaust gas, and reduces the exhaust efficiency (in the internal combustion engine of the exhaust gas). Ease of discharge from the plant).

  Next, a second embodiment will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected and shown to the same part, and the detailed description is abbreviate | omitted. In this embodiment, in addition to the configuration of the first embodiment described above, a bendable bellows-like joint 6 is provided in the middle of the outer tube 11.

  As shown in FIG. 7, the joint 6 is a member (for example, a member constituting the exhaust passage A) due to mismatch between vibration transmitted from the engine e and vibration generated in the catalyst device 2 and the silencer 4 during traveling. As shown in FIG. 8 (a), the joint 6 is roughly composed of an inner member 61 and an outer surface that covers the inner member 61. The inner member 61 and the outer member 62 are integrally joined by welding to the outer tube 11 and the other end to the flange 13 by attachment members 63 and 63, respectively.

  The inner tube 12 is disposed in a portion of the outer tube 11 that extends over substantially the entire length in the flow path direction of the bellows-shaped joint 6, and is curved in a bellows shape by covering the inner surface of the joint 6. Therefore, it is possible to prevent the exhaust gas from directly hitting the inner member 61 and to increase the flow resistance, and it is possible to prevent the exhaust efficiency from being lowered even in the exhaust pipe structure in which the joint 6 is provided. Even in the second embodiment, the same effect as the first embodiment was obtained.

  By the way, in the first and second embodiments described above, the example in which the flux adjusting unit 10 is provided in the middle of the front pipe 1 has been described. However, the flux adjusting unit 10 is configured as shown in FIG. The intermediate pipe 3 may be provided in the middle, or the tail pipe 5 may be provided in the middle (not shown). Although not shown, the exhaust passage A may be provided with two or more flux adjusting units 10, 10,.

  In the first and second embodiments described above, an automobile engine has been described as an internal combustion engine. However, other internal combustion engines, for example, an engine for a motorcycle, an engine for a generator, etc. It may be applied to institutions.

A Exhaust flow path e Engine (internal combustion engine)
1 Front pipe 3 Intermediate pipe 10 Flux adjustment part 11 Outer pipe 12 Inner pipe

Claims (3)

A substantially cylindrical outer tube constituting an exhaust passage of the internal combustion engine;
An inner tube that is detachably provided in the middle of the outer tube and has an axial core that matches the axial core of the outer tube;
The inner pipe has a tapered portion whose outer peripheral edge on the upstream side of the exhaust flow path contacts the inner wall of the outer pipe over the entire circumference and gradually decreases in diameter toward the downstream side of the exhaust flow path. An exhaust pipe structure for an internal combustion engine. In the middle of the outer tube, it has a flexible bellows-like joint,
2. The exhaust pipe structure for an internal combustion engine according to claim 1, wherein the inner pipe is located in a portion of the outer pipe that extends over substantially the entire length in the flow path direction of the bellows-like joint. In the middle of the substantially cylindrical outer pipe constituting the exhaust flow path of the internal combustion engine, an inner pipe having an axis that matches the axis of the outer pipe is detachably provided,
The inner pipe has a tapered portion whose outer peripheral edge on the upstream side of the exhaust flow passage is in contact with the inner wall of the outer pipe over the entire circumference and gradually decreases in diameter toward the downstream side of the exhaust flow passage. And
An internal combustion engine that adjusts output characteristics of the internal combustion engine by changing a ratio of a flow passage area at an end portion on the downstream side of the taper portion and a flow passage area at an end portion on the upstream side of the taper portion. Output adjustment method.

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