Exhaust component support structure

Abstract

To provide an exhaust component support structure that can suppress vibration transmission.SOLUTION: An exhaust component support structure includes an exhaust pipe that is disposed while being folded back in a U-shape or S-shape in a vehicle horizontal direction orthogonal to a vehicle longitudinal direction, and supports both ends of an exhaust muffler where a first support point and a second support point that respectively support both ends of the exhaust muffler are positioned on a front side of the vehicle relative to a central line that passes through the center of gravity of the exhaust muffler.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a support structure for exhaust components.

Background Art

[0002] Patent Document 1 discloses a technique in which an engine and an exhaust silencer are arranged opposite to each other in the direction of the output shaft of the engine, and a low-rigidity portion with locally reduced rigidity is provided in the middle of the exhaust pipe leading from the engine to the exhaust silencer in order to suppress the transmission of vibration from the engine to the exhaust silencer.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique disclosed in Patent Document 1, since the exhaust silencer is supported away from the center of gravity of the exhaust components, there is room for improvement from the viewpoint of vibration transmission.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a support structure for exhaust components capable of suppressing vibration transmission.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, a support structure for exhaust components according to the present invention is a support structure for exhaust components in which an exhaust pipe is folded back in a U shape or an S shape in the vehicle left-right direction orthogonal to the vehicle front-rear direction and both ends of an exhaust silencer are supported, and a first support point and a second support point for respectively supporting both ends of the exhaust silencer are located in front of the vehicle with respect to a center line passing through the center of gravity of the exhaust silencer.

Effects of the Invention

[0007] The support structure of the exhaust component according to the present invention has the effect of suppressing vibration transmission.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of a support structure of an exhaust component according to the present invention will be described. Note that the present invention is not limited by the present embodiment.

[0010] FIG. 1 is a diagram showing a schematic configuration of a support structure for an exhaust component according to an embodiment. As shown in FIG. 1, the support structure for an exhaust component according to the embodiment is applied to a vehicle having an engine 1 which is an internal combustion engine and an exhaust system 2. The exhaust system 2 includes, as exhaust components, an exhaust pipe 21 through which exhaust gas from the engine 1 flows, a catalyst device 22 for purifying the exhaust gas, and a muffler 23 which is an exhaust silencer device. The catalyst device 22 and the muffler 23 are provided in this order in the middle of the exhaust pipe 21 in the flow direction of the exhaust gas discharged from the engine 1 and flowing through the exhaust pipe 21, as indicated by the white arrow in FIG. 1. In the following description, "upstream" or "upstream side" means upstream or the upstream side in the flow direction of the exhaust gas, and "downstream" or "downstream side" means downstream or the downstream side in the flow direction of the exhaust gas. At least a part of the center line of the portion of the exhaust pipe 21 disposed upstream of the muffler 23 is substantially parallel and in the opposite direction to the direction of the muffler center line CL1 from the upstream end to the downstream end of the muffler 23 in the vehicle left-right direction orthogonal to the vehicle front-rear direction. That is, the exhaust pipe 21 is a pipe folded back in a U shape or an S shape in the vehicle left-right direction orthogonal to the vehicle front-rear direction.

[0011] Further, at the upstream end and the downstream end of the muffler 23, a first support portion 31 and a second support portion 32 for supporting both ends of the muffler 23 with respect to the bottom surface of the vehicle are provided. The first support portion 31 and the second support portion 32 are each constituted by an elastic body. In the support structure for an exhaust component according to the embodiment, both of the two first support points A and the second support point B in the first support portion 31 and the second support portion 32 for supporting the muffler 23 are positioned in front of the vehicle with respect to the muffler center line CL1 passing through the center of gravity Gm of the muffler 23.

[0012] FIG. 2 is a diagram showing a case where the first support point A and the second support point B of the muffler 23 are located on the muffler center line CL1. In the case of the support structure for an exhaust component as shown in FIG. 2, due to the mass of the portion of the exhaust pipe 21 upstream of the muffler 23, the center of gravity G0 of the entire exhaust system 2 exists upstream, that is, in front of the vehicle with respect to the center of gravity Gm of the muffler 23 (the center of gravity position of the muffler 23 alone).

[0013] In the support structure of the exhaust component as shown in FIG. 2, the first support point A of the first support portion 31 for supporting the muffler 23 and the second support point B of the second support portion 32 are located at positions sandwiching the center of gravity Gm of the muffler 23 on the muffler center line CL1. Therefore, in order to statically support the center of gravity G0 of the entire exhaust system 2 located in front of the vehicle with respect to the center of gravity Gm of the muffler 23, it is necessary to support the exhaust pipe 21 at a total of three points including another point (third support point C) on the other exhaust pipe 21. In the support structure of the exhaust component shown in FIG. 2, the third support point C is located at the third support portion 33 constituted by an elastic body for supporting the catalytic converter 22 with respect to the bottom surface of the vehicle, which is provided at the upstream end of the catalytic converter 22. And in the support structure of the exhaust component shown in FIG. 2, the load sharing at the first support point A, the second support point B, and the third support point C for supporting the weight of the entire exhaust system 2 is relatively dispersed, and it is necessary for the third support point C to also share the load. That is, there are limitations in setting the rigidity of the elastic body arranged at the third support point C to be small.

[0014] Therefore, in the support structure of the exhaust component according to the embodiment, as shown in FIG. 3, when the third support point C is located at the third support portion 33 provided at the upstream end of the catalytic converter 22, the first support point A and the second support point B of the first support portion 31 and the second support portion 32 for supporting the muffler 23 are located in front of the vehicle with respect to the muffler center line CL1. As a result, the distance between the center of gravity G0 of the entire exhaust system 2 and the line segment AB connecting the first support point A and the second support point B becomes shorter, and the load sharing ratio for supporting the weight of the entire exhaust system 2 increases for the first support point A and the second support point B, and conversely, the load sharing ratio of the third support point C decreases.

[0015] As the most desirable form, the first support point A and the second support point B are arranged such that the center of gravity G0 of the entire exhaust system 2 is located on the line segment AB. In this case, the shared load of the third support point C becomes zero. At this time, it becomes unnecessary to support at the third support point C, and the vibration suppression effect becomes the highest. For example, even if it does not reach that point, by positioning the first support point A and the second support point B in front of the vehicle with respect to the muffler center line CL1, the shared load of the third support point C can be reduced, so the rigidity of the elastic body arranged at the third support point C can be made smaller, contributing to vibration suppression. That is, in the support structure of the exhaust component according to the embodiment, while achieving a balance of static shared loads, dynamic vibration transmission can be suppressed.

[0016] Here, the reason for wanting to reduce the rigidity of the elastic body arranged at the third support point C is as follows. When the engine 1 operates, it causes complex vibrations such as torque fluctuations due to repeating the exhaust process, intake process, compression process, and expansion stroke, and inertial force vibrations associated with the piston reciprocation, and applies vibrations to the fastening part between the engine 1 and the exhaust pipe 21. On the other hand, the entire exhaust system 2 has a plurality of resonance frequencies, and when vibrations are applied at a frequency close to its resonance frequency, the inherent vibration mode is excited. Among these vibration modes, in many cases, the one with the largest amplitude is the fundamental vibration with the longest wavelength and the fewest number of nodes. This fundamental vibration will be described with reference to FIGS. 4 and 5. Note that FIG. 5 graphs the distance from the connection point between the engine 1 and the exhaust pipe 21 on the center line CL2 of the exhaust pipe 21 in FIG. 4 on the horizontal axis, and the vertical displacement (vertical vibration displacement) in the vertical direction due to vibrations at each point on the center line CL2 of the exhaust pipe 21 on the vertical axis.

[0017] The fundamental vibration on this exhaust pipe 21 has the following characteristics. As the first characteristic, at the connection point between the engine 1 and the exhaust pipe 21 ((1) in FIGS. 4 and 5), since the exhaust pipe 21 is constrained by the engine 1, it becomes a fixed end (node). As the second characteristic, at the center of gravity Gm of the muffler 23 ((5) in FIGS. 4 and 5), since the inertia is large, it becomes a node.

[0018] In such a case, at the upstream end point of the muffler 23 ((4) in FIGS. 4 and 5) and the downstream end point of the muffler 23 ((6) in FIGS. 4 and 5), since it is close to a node, the amplitude is small, and at other points ((2) and (3) in FIGS. 4 and 5), it is close to an antinode and the amplitude is large. That is, if the third support point C is set upstream of the muffler 23, since its amplitude is larger than that of the first support point A and the second support point B on the muffler 23, in order not to transmit excessive vibration to the vehicle body, it is required to reduce the rigidity of the elastic body at the third support point C.

Description of Symbols

[0019] 1 Engine 2 Exhaust system 21 Exhaust pipe 22 Catalytic device 23 Muffler 31 First support part 32 Second support part 33 Third support part

Claims

【Claim 1】 A support structure for exhaust components that supports both ends of an exhaust silencer, wherein the exhaust pipe is folded back in a U-shape or an S-shape in the left-right direction of the vehicle that is orthogonal to the front-rear direction of the vehicle, A support structure for exhaust components, characterized in that a first support point and a second support point that respectively support both ends of the exhaust silencer are positioned in front of the vehicle with respect to a center line passing through the center of gravity of the exhaust silencer.

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