JP3802861B2 - Catalyst cover holding structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a holding structure for a catalyst cover that covers a catalyst case of a catalytic converter main body, which is mainly interposed in an exhaust system connected to an exhaust port of an automobile engine.
[0002]
[Prior art]
In general, a catalytic converter main body is connected to an exhaust system of an automobile engine in order to purify harmful components such as HC, CO ₂ , NOx in the exhaust flowing therethrough (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP, 2000-491428, A The above-mentioned catalytic converter main part is as follows.
1) Since it is heated to a high temperature by reaction purification heat of harmful components, its surroundings are not affected by heat, for example, to prevent ignition of dead grass.
[0004]
2) In order to promote the activation of the catalytic converter, keep the temperature to prevent the temperature of the exhaust gas from decreasing.
[0005]
3) Protect to prevent interference with obstacles such as splashes and flying stones.
[0006]
4) Improve the appearance of the catalytic converter.
[0007]
It is necessary to take measures such as the above, and as such measures, there is already known one in which the entire outer periphery of the catalytic converter body is covered with a catalyst cover (see FIG. 8).
[0008]
[Problems to be solved by the invention]
By the way, the exhaust generated by the operation of the engine flows to the exhaust system with exhaust pulsation, and the exhaust pulsation is also transmitted to the catalytic converter connected to the exhaust system, and the exhaust velocity energy and the pressure are reduced. The catalyst cover is also transmitted to the catalyst cover, and the inner surface of the catalyst cover is vibrated to generate surface vibration mainly based on high-frequency vibrations, which radiates from the catalyst cover as radiated sound. There is a problem that the surrounding air is vibrated and causes noise.
[0009]
To solve this problem, as shown in FIG. 8, a case bracket is fixed to the catalyst case of the catalytic converter, and a vibration absorbing member made of a stainless mesh material is interposed between the case bracket and the catalyst cover. In the past, vibration reduction means has been proposed that uses the elastic force in the compression direction of the vibration absorbing member to reduce the transmission of high-frequency vibrations from the catalyst case to the catalyst cover. A sufficient vibration reduction effect cannot be obtained, and the above problem has not been solved.
[0010]
The present invention has been made in view of such circumstances, and the transmission of mainly high-frequency vibrations of exhaust gas from the catalytic converter to the catalyst cover is achieved by the sliding frictional force of the friction holding means provided between the catalytic converter and the catalyst cover. It is an object of the present invention to provide a novel catalyst cover holding structure which can be attenuated as much as possible to greatly reduce the generation of the radiated sound and solve the problem.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 purifies harmful components of exhaust flowing through the exhaust system connected to the exhaust port of the engine and interposed in the exhaust system supported by the vehicle body frame 1. A catalyst cover holding structure covering the catalytic converter body,
Friction holding means is provided between the catalyst case of the catalytic converter main body and the catalyst cover, and the friction holding means generates a vertical sliding friction force between the catalyst case and the catalyst cover, and this sliding friction force. Thus, the catalyst cover is held in the catalyst case so that vibration transmission from the catalyst converter body to the catalyst cover can be reduced. According to such a feature, the catalyst cover is transmitted from the catalyst case of the catalyst converter body to the catalyst cover. The vibration sound, mainly high-frequency vibration, can be effectively reduced by the sliding friction in the vertical direction by the friction holding means, and the radiated sound emitted from the catalyst cover can be greatly reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0013]
In this embodiment, the present invention is applied to an automobile equipped with a multi-cylinder engine. FIG. 1 is a side view of an exhaust system of the engine having the holding structure of the present invention, and FIG. FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a sectional view taken along line 4-4 in FIG. 2, and FIG. FIG. 6 is an exploded perspective view of the elastic holding means, and FIG. 7 is a graph showing a change in the radiated sound of the catalyst cover with respect to the engine speed.
[0014]
In FIG. 1, a multi-cylinder engine E for running the automobile is placed on a body frame 1 of the automobile through front and rear engine mounts 2 and 3 (the crankshaft 4 is orthogonal to the longitudinal direction of the automobile). Mounted in the direction of The engine E is a four-cycle serial type, and a cylinder block 5 in which a plurality of cylinders are arranged in parallel, a cylinder head 6 coupled thereon, a head cover 7 covering the upper surface of the cylinder head 6, An oil pan 8 coupled to the lower surface of the crankcase portion of the cylinder block 5 is provided.
[0015]
The engine E has an oscillating rotation shaft parallel to the crankshaft 4 through the center of gravity G, that is, a rolling shaft LL. When the vehicle is running, the engine E is displaced forward and backward with the rolling shaft LL serving as a rolling center. .
[0016]
A plurality of intake ports 11 are opened in parallel on the front side (left side in FIG. 1) of the engine E, and an intake system In is connected to the intake ports 11, and the rear side of the engine E (in FIG. 1). On the right side, a plurality of exhaust ports 12 are opened in parallel, and an exhaust system Ex is connected to these exhaust ports 12.
[0017]
The exhaust system Ex includes an exhaust manifold 14 whose upstream end is integrally connected to the exhaust port 12 and an exhaust pipe 15 connected to its downstream end. The exhaust pipe 15 includes a first exhaust pipe section 16 on the upstream side and a second exhaust pipe section 17 on the downstream side, and a spherical surface is provided between the exhaust manifold 14 and the first exhaust pipe section 16. A joint 18 is interposed, and a flexible tube 19 is interposed between the first exhaust pipe portion 16 and the second exhaust pipe portion 17. Further, in the middle of the second exhaust pipe portion 17, A catalytic converter CA having a catalyst cover holding structure according to the present invention is connected, and a silencer (not shown) is connected to the downstream side of the catalytic converter CA.
[0018]
By the way, the exhaust system Ex is provided with the spherical joint 18 and the flexible tube 19, and the engine E is greatly subjected to rolling vibration, that is, rolling displacement, due to traveling of the automobile, in particular, sudden start, sudden acceleration, sudden deceleration, and the like. In this case, the displacement is effectively absorbed, and the vehicle vibration caused by the rolling displacement of the engine E can be reduced as much as possible.
[0019]
The plurality of distribution pipes 14a of the exhaust manifold 14 are connected to the exhaust ports 12 of the engine E at their upstream ends, are curved in an elbow shape, and gradually gather toward the downstream side. The downstream ends thereof are opened downward, and the downstream ends thereof are integrally connected to one exhaust collecting portion 14b. The exhaust collecting portion 14 b is connected to the upstream end of the first exhaust pipe portion 16 via the spherical joint 18 near the rear surface of the engine E.
[0020]
The spherical joint 18 is airtightly sandwiched between a first connection flange 18a constituting one joint half, a second connection flange 18b constituting the other joint half, and both the flanges 18a and 18b. And a spherical gasket 18c. The outer peripheral portions of the first and second connection flanges 18 a and 18 b are elastically connected via a pressure coil spring 49 by a plurality of bolts and nuts 48.
[0021]
A stay 29 is fixed to one joint half of the spherical joint 18 on the side connected to the exhaust manifold 14, that is, the first connection flange 18 a, and the stay 29 faces the rear surface of the engine E. It extends forward, and a bent mounting portion at the tip thereof is fixed to the rear surface of the cylinder block 5 of the engine E. Therefore, when the engine E is rollingly displaced about the rolling axis LL, the other joint half 18b is rotationally displaced via the spherical gasket 18c with respect to the one joint half 18a.
[0022]
As described above, the first exhaust pipe portion 16 whose upstream end is connected to the spherical joint 18 has a curved portion that curves convexly toward the engine E side, and the upstream half portion 16a thereof is the engine half. It extends downward with respect to E, and its downstream half 16b extends rearward with respect to the engine E, and is formed in an elbow shape in a side view. The front end of the flexible tube 19 is connected to the downstream end of the first exhaust pipe portion 16 that is opened rearward. The flexible tube 19 is extended in the front-rear direction, can be expanded and contracted in the front-rear direction, and mainly absorbs the front-rear direction component of the rolling displacement of the engine E.
[0023]
In addition, since the said flexible tube 19 employs a conventionally well-known thing, the detailed description is abbreviate | omitted.
[0024]
The downstream end of the flexible tube 19 is integrally coupled to the upstream end of the second exhaust pipe portion 17 of the exhaust pipe 15, and the first exhaust pipe portion 16 and the second exhaust pipe portion 17 are: It communicates via the flexible tube 19.
[0025]
The second exhaust pipe portion 17 extends substantially horizontally in the longitudinal direction of the automobile, and a catalytic converter CA is connected to the middle of the second exhaust pipe portion 17. Further, the second exhaust pipe portion 17 is illustrated at the downstream end of the second exhaust pipe portion 17. A tail pipe that opens to the atmosphere is connected through a silencer that does not.
[0026]
The second exhaust pipe portion 17 is supported by the vehicle body frame 1 via the elastic support means S, and the vibration acting on the exhaust system Ex is also attenuated by the elastic support means S, and is transmitted to the vehicle body. It is reduced.
[0027]
Next, with reference to FIGS. 2 to 5, the catalytic converter CA 20, the catalytic converter body 20, the catalytic cover 30 that covers the outer periphery thereof, and the holding structure that holds them will be described.
[0028]
The catalyst case 21 of the catalytic converter main body 20 is formed by integrally forming a cylindrical cylindrical portion 21a, an inlet cone portion 21b on the exhaust introduction side, and an outlet cone portion 21c on the exhaust discharge side. As shown, a polygonal plate-shaped upstream connection flange 22 is welded to the end of the inlet cone 21b, and a joint pipe 23 is connected to the end of the outlet cone 21c as shown in FIGS. A polygonal plate-like downstream connection flange 24 is welded to the intermediate plate. The connection flanges 22 and 24 are integrally connected to the connection flanges on the upstream side 17a and the downstream side 17b of the second exhaust pipe 17 by a plurality of connection bolts 25 and 26, respectively.
[0029]
In the catalyst case 21, a columnar carrier 27 carrying a catalyst is supported via a holding mat 28 as usual, and the support structure of the carrier 27 in the catalyst case 21 is conventionally known. Detailed description thereof will be omitted.
[0030]
The outer peripheral surface of the catalyst case 21 of the catalytic converter main body 20 is covered with a catalyst cover 30 over a substantially entire area with a gap (about 5 mm). The catalyst cover 30 is formed in a sealed shape so as to follow the outer shape of the catalyst case 21 by integrally connecting the upper case 31 and the lower case 32, and before the cylindrical portion 30a and the front and back are integrally integrated, It consists of rear cone parts 30b and 30c. A plurality of reinforcing ribs 33 are integrally formed in the circumferential direction at intervals in the longitudinal direction of the cylindrical portion 30a. On both side edges of the upper case 31 and the lower case 32 in the longitudinal direction, strip-shaped upper and lower joint flanges 31a and 32a are integrally projected substantially horizontally toward the outside, and these joint flanges 31a and 32a are extended. The sealed catalyst cover 30 is formed by airtight joining by welding or the like.
[0031]
Front and rear cover stays 35 and 36 are fixed to left and right corner portions of the front and rear ends of the catalyst cover 30 formed by integrally joining the upper case 31 and the lower case 32, respectively. Although these cover stays 35 and 36 have the same structure, the phases of the positions fixed to the catalyst cover 30 are shifted from each other by approximately 90 °.
[0032]
Each of the front and rear cover stays 35, 36 is formed in an angle by bending a strip-shaped metal plate into an L shape, and has horizontal portions 35a, 36a and upright portions 35b, 36b. A hole is drilled.
[0033]
2 and 3, the horizontal portion 35a of the front cover stay 35 is sandwiched between the upper and lower joint flanges 31a and 32a on the left and right of the front end of the catalyst cover 30, and the joint flange 32a of the lower case 32 and By screwing a bolt 38 in the horizontal portion 35a of the front cover stay 35 into a weld nut 39 welded to the joint flange 31a of the upper case 31 through the bolt hole of the horizontal portion 35a from below, The horizontal portion 35a of the pair of left and right front cover stays 35 is fixed to the left and right ends of the catalyst cover 30 between the upper and lower joint flanges 31a and 32a, as shown in FIGS. The horizontal portion 36a of the rear cover stay 36 is sandwiched between the joint flange 32a of the lower case 32 and the horizontal portion 3 of the rear cover stay 36. A bolt bolt A is connected to a weld nut 42 welded to the upper case 31 with a coupling bolt 41 penetrating from the lower side of the bolt hole 41 to the left and right of the rear end of the catalyst cover 30, and the horizontal pair of left and right rear cover stays 36. The part 36a is fixed.
[0034]
As shown in FIGS. 2 and 3, the opposite ends of the front case bracket 44 are disposed on opposite surfaces of the front cover stays 35 on the left and right front cover stays 35 at the front end of the catalyst case 21 via friction holding means HF, which will be described later. Is kept floating. As shown in FIG. 2, the front case bracket 44 is configured by a frame member having an angled cross section and extends in the left-right direction so as to cross the upper front portion of the catalyst cover 30. The upstream connection flange 22 fixed to the front end is welded.
[0035]
As shown in FIGS. 2 and 5, the rear case bracket 46 is disposed on the surface of the upright portion 36 b facing the front of the left and right rear cover stays 36 at the rear end of the catalyst case 21 via friction holding means HF described later. Both ends are held in a floating state. As shown in FIG. 2, the rear case bracket 46 is configured by a frame member formed by bending a plate member, and extends in the left-right direction so as to cross the upper rear portion of the catalyst cover 30, and an intermediate portion thereof is a catalyst case. 21 is welded to the joint pipe 23 which is fixed to the rear end.
[0036]
Accordingly, the left and right corner portions, that is, the four corners of the front end and the rear end of the catalyst cover 30 are fixed to the front and rear cover stays 35 and 36 and the friction holding means HF described later, and the catalyst case of the catalytic converter main body 20. 21 are supported in a floating state by front and rear case brackets 44 and 46 which are integrally provided at the front and rear portions of 21.
[0037]
Next, the friction holding means HF according to the present invention will be described mainly with reference to FIG. 6. The friction holding means HF includes a pair of sliding friction members 50 and 51 and the sliding friction members 50 and 51. It is comprised from the distance collar 52 with a flange supported without compressing, the volt | bolt 53 which penetrates them, and the nut 54 screwed together there. Each of the pair of sliding friction members 50 and 51 is formed in a grommet shape by compression molding a stainless mesh material as a metal mesh, and the sliding friction surfaces thereof are directed in the vertical direction , that is, in the vertical direction , and the inner surfaces thereof. Are opposed to each other, and the surfaces of the upright portions 35b and 36b of the front or rear cover stays 35 and 36 are sandwiched therebetween. The flanged distance collar 52 is configured by caulking and fixing the other flange portion 52c to the other end of the shaft portion 52a integrally formed with one flange portion 52b at one end. The shaft portion 52a of the distance collar 52 is The pair of sliding friction members 50 and 51 are penetrated, and the flange portions 52b and 52c on both sides thereof are in contact with the outer surfaces of the pair of sliding friction members 50 and 51. The bolt 53 passes through the distance collar 52, and a nut 54 is screwed to the threaded portion thereof, but the pair of sliding friction members 50 and 51 are not compressed and are always slid by a predetermined sliding force by their elastic force. Dynamic friction force is obtained.
[0038]
The friction holding means HF includes front and rear case brackets fixed to the catalyst case 30 side of the front and rear cover stays 35 and 36, and the front and rear case brackets fixed to the catalyst case 21 side of the catalytic converter. 44 and 46 are provided. That is, as shown in FIG. 3, on the left and right of the front end of the catalytic converter CA, as described above, the standing portion 35 b of the front cover stay 35 fixed between the upper case 31 and the lower case 32 is the shaft portion 52 a of the distance collar 52. One end surface of the front case bracket 44 that is sandwiched between the friction surfaces in the vertical direction of the pair of sliding friction members 50 and 51 that pass through the flange and that is fixed to the catalyst case 21 side is one flange portion 52b of the distance collar 52. The bolt 53 passes through the bolt holes of the distance collar 52 and the front case bracket 44, and the nut 54 is screwed onto the bolt 53 so that the front portion of the catalyst cover 30 is attached to the catalytic converter body 20. The catalyst case 21 is floatingly supported via the elastic holding means HF, and is When media cover 30 is displaced up and down, they are subjected to sliding frictional resistance in the vertical direction by the sliding frictional force between the friction surface and the upstanding portion 35b of the pair of sliding friction members 50 and 51 of the friction holding means HF. Further, as shown in FIG. 5, at the left and right of the rear end of the catalytic converter CA, a pair of upright portions 36 b of the rear cover stay 36 fixed between the upper case 31 and the lower case 32 penetrates the shaft portion 52 a of the distance collar 52. One end surface of the rear case bracket 46 that is sandwiched between the friction surfaces in the vertical direction of the sliding friction members 50 and 51 and fixed to the catalyst case 21 side is brought into contact with the outer surface of the flange portion 52c of the distance collar 52, and the bolt 53 penetrates the bolt holes of the distance collar 52 and the front case bracket 46 and screws the nuts 54 onto the bolts 53, whereby the rear part of the catalyst cover 30 is brought into contact with the catalyst case 21 of the catalytic converter body 20. It is floatingly supported through the holding means HF, the catalyst cover 30 in the vertical direction with respect to the catalyst case 21 When displaced, they are subjected to sliding frictional resistance in the vertical direction by the sliding frictional force between the friction surface and the upstanding portion 36b of the pair of sliding friction members 50 and 51 of the friction holding means HF.
[0039]
Next, the operation of this embodiment will be described.
[0040]
Now, according to the operation of the engine E, the exhaust discharged from the exhaust port 12 is upstream of the exhaust manifold 14, the spherical joint 18, the first exhaust pipe portion 16, the flexible tube 19, and the second exhaust pipe portion 17. , The catalytic converter main body 20, the downstream portion of the second exhaust pipe portion 17, and a silencer (not shown), while harmful components such as HC and CO are purified, and the exhaust sound is silenced by the silencer. To be released.
[0041]
By the way, the exhaust generated by the operation of the engine E flows to the exhaust system Ex with exhaust pulsation, and the exhaust pulsation is transmitted to the catalytic converter body 20 connected to the exhaust system Ex, and the exhaust velocity energy and The pressure is also transmitted from the catalytic converter main body 20 to the catalyst cover 30, and the inner surface of the catalyst cover 30 is vibrated to generate surface vibration based on high-frequency vibration in the catalyst cover 30, which is the catalyst cover. In this embodiment, the vibration is radiated as a radiated sound, and the surrounding air is vibrated. However, in this embodiment, the vibration is caused by the sliding friction members 50 and 51 made of stainless mesh material and the cover stay. The vibration transmission from the catalytic converter main body 20 to the catalyst cover 30 can be significantly reduced by utilizing the sliding frictional resistance between 35 and 36.
[0042]
Thus, the sliding friction members 51 and 52 made of a stainless mesh material than the one (see FIG. 8) in which the vibration transmission is reduced by utilizing the elastic force in the compression direction of the stainless mesh as a vibration absorbing member. If the vibration transmission is reduced by the vertical sliding friction (Coulomb friction) force between the cover stays 35 and 36, the vibration transmission reduction effect is larger, and the good vibration transmission reduction effect can be obtained over a wide range of engine E. It can be obtained in the rotational speed region.
[0043]
In FIG. 7, when the conventional catalyst cover 30 holding structure shown in FIG. 8 and the catalyst cover 30 holding structure in this embodiment are used, the rotation speed of the engine E (2000 to 6000 rpm) from the catalyst cover 30 is shown. The graph by the experimental result which showed the change rate of the sound pressure (dB) of a radiated sound is shown, the continuous line shows this Example and a dotted line has shown the conventional thing. As is apparent from this graph, in this example, the sound emitted from the catalyst cover 30 is reduced over an operating range (2000 to 6000 rpm) where the engine speed is wider than the conventional one. Recognize.
[0044]
Although one embodiment of the present invention has been described above, the present invention is not limited to that embodiment, and various embodiments are possible within the scope of the present invention.
[0045]
For example, in the above embodiment, the case where the catalyst cover holding structure according to the present invention is implemented in a multi-cylinder four-cycle engine has been described, but it is needless to say that this can be implemented in other types of engines. Moreover, although the said Example demonstrated the case where a stainless mesh material was used as a sliding friction member of a friction holding means, it replaces with this and you may use another sliding friction member of the same effect. Further, in the above embodiment, the friction holding means is provided on the catalyst case side and the cover stay is provided on the catalyst cover side. However, the friction holding means is provided on the catalyst cover side and the cover stay is provided on the catalyst case side. Also good.
[0046]
【The invention's effect】
As described above, according to the first aspect of the present invention, in the catalyst cover holding structure, vibrations, mainly high-frequency vibrations transmitted from the catalyst case of the catalytic converter body to the catalyst cover, are applied in the vertical direction by the friction holding means. It is possible to effectively reduce the radiated sound radiated from the catalyst cover by effectively reducing the sliding frictional force .
[Brief description of the drawings]
FIG. 1 is a side view of an exhaust system of an engine provided with a holding structure of the present invention. FIG. 2 is an enlarged perspective view of a portion indicated by an arrow 2 in FIG. 4 is a sectional view taken along line 4-4 in FIG. 2. FIG. 5 is an enlarged sectional view taken along line 5-5 in FIG. 2. FIG. 6 is an exploded perspective view of friction holding means. [Fig. 8] A cross-sectional view of a conventional catalyst converter body catalyst case and catalyst cover holding part [Description of symbols]
1 ... Body frame 12 ... Exhaust port 20 ... Catalytic converter body 21 ... Catalyst case 30 ... Catalyst cover E ... Engine Ex ... Exhaust system HF ... Friction holding means

Claims (1)

A catalytic converter main body that is connected to an exhaust port (12) of the engine (E), is interposed in an exhaust system (Ex) supported by the vehicle body frame 1, and purifies harmful components of exhaust flowing in the exhaust system (Ex) (20) a structure for holding the catalyst cover that covers (20),
Friction holding means (HF) is provided between the catalyst case (21) of the catalytic converter body (20) and the catalyst cover (30), and the friction holding means (HF) includes the catalyst case (21) and the catalyst cover. (30), a sliding frictional force in the vertical direction is generated, and the catalytic cover (30) is held in the catalyst case (21) by this sliding frictional force, from the catalytic converter body (20) to the catalyst cover (30). A catalyst cover holding structure of a catalytic converter, characterized in that vibration transmission of the catalyst can be reduced .

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