JP2015137594A - exhaust system support structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pair of hanger rubbers supporting an exhaust system from simultaneously falling by deterioration of durability.SOLUTION: A center exhaust pipe 5 of an exhaust system 3 has a hanger stay 12 fixed to its bottom part, and both ends of the hanger stay 12 are supported through first and second hanger rubbers 9, 10 with respect to a floor bracket 11 fixed to the lower side of a vehicle body floor 2. The first hanger rubber 9 mainly comprises an EPDM-based rubber, and the second hanger rubber 10 mainly comprises a silicon rubber. Since both rubbers have different characteristics, deterioration of durability is not advanced simultaneously, and thus the rubbers can be prevented from simultaneously falling.

Description

  The present invention relates to an exhaust system support structure in which a pair of first and second hanger rubbers that suspend an exhaust system member on a vehicle body frame have different characteristics.

  Conventionally, in vehicles such as automobiles, when supporting exhaust pipes and mufflers, which are exhaust system parts, on the bottom of the vehicle body, they are suspended under the vehicle body floor via a hanger rubber to reduce vibration and vibration of the exhaust system. The vibration transmission to the vehicle body side is suppressed.

  By the way, the vibration generated in the exhaust system greatly fluctuates depending on the road surface condition from idling to stopping at a high speed. In addition, the exhaust heat characteristics also vary greatly between the cold start and the high load operation. In particular, in recent high performance vehicles, the demands for vibration and heat are becoming stricter even for hanger rubber that absorbs vibrations in the exhaust system, and it is necessary to respond to these demands with single characteristics hanger rubber. Has become difficult.

  In addition, the hanger rubber may be damaged due to contact with an obstacle existing on the road, etc., but the rubber with the same physical properties is usually used. If it breaks at the same time, the exhaust system is no longer supported, and this may immediately impede subsequent travel.

  As a countermeasure for these, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2010-23603), a technique for improving vibration characteristics and strength by forming one hanger rubber at a plurality of portions. It has been known.

JP 2010-23603 A

  However, since the hanger rubber disclosed in the above-mentioned document has a single hanger rubber characteristic, when supporting exhaust system parts with a pair of left and right hanger rubber, cracks at the damaged site when damaged due to external force are received. Deterioration of durability, such as progress, deterioration of durability due to long-term use, progress of decrease in tensile strength when foreign objects are sandwiched, progress to tear rupture starting from damaged part, etc. It will be the same. As a result, the pair of hanger rubbers are likely to fall off at the same time, so that it is necessary to take another measure to prevent this, resulting in an increase in cost due to an increase in the number of parts.

  In addition, since it is a single member, it is necessary to incorporate a complicated shape and size for absorbing vibration in order to improve vibration resistance performance, and there is a problem that the product cost per part increases.

  In view of the above circumstances, the present invention can not only be manufactured in a simple shape and at low cost, but can also meet the demands of a high-performance vehicle and prevent it from falling off at the same time. It is an object of the present invention to provide an exhaust system support structure that does not require the above-described measures and can realize a reduction in product cost.

  According to the present invention, in an exhaust system support structure including a pair of first and second hanger rubbers for suspending an exhaust system member on a vehicle body frame, the first hanger rubber and the second hanger rubber have a plurality of different characteristics.

  According to the present invention, the first and second hanger rubbers have a plurality of different characteristics. For example, even when the first and second hanger rubbers have substantially the same shape and size, the change in hardness with respect to temperature and the tension with respect to temperature. It is possible to vary the progress of the decrease in durability such as change in strength and tear strength. As a result, excellent durability can be obtained under traveling conditions and temperature conditions, and it is possible to sufficiently meet the demands of recent high performance vehicles. In addition, it is not necessary to take measures to prevent both hanger rubbers from dropping off at the same time, and the product cost can be reduced accordingly. Furthermore, since it is not necessary to make the shape of each hanger rubber complicated, the product cost can be further reduced.

The top view which shows the structure of the exhaust system arranged under the body floor II-II sectional view of FIG. (A) is a characteristic diagram showing changes in the elastic modulus of EPDM rubber and silicon rubber with respect to temperature changes, and (b) is a characteristic diagram showing changes in the tensile strength of EPDM rubbers and silicon rubber with respect to temperature changes.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 in FIG. 1 denotes a vehicle body, and an exhaust system 3 is disposed below a vehicle body floor 2 as a vehicle body frame of the vehicle body 1. The exhaust system 3 has an upstream end communicating with an exhaust manifold of an engine mounted in a front engine room (not shown) and a downstream end extending to the rear portion of the vehicle body 1.

  The exhaust system 3 includes, in order from the upstream side, a front exhaust pipe 4 that communicates with the exhaust manifold, a center exhaust pipe 5 that serves as an exhaust system member that communicates downstream thereof, and a rear exhaust pipe 6 that communicates downstream thereof. The middle of the front exhaust pipe 4 is formed by the flexible pipe 4a. Further, a muffler pipe 7 a of the muffler portion 7 is communicated with the downstream end of the rear exhaust pipe 6, and the muffler portion 7 is provided with a muffler 7 b. Although not shown, the front exhaust pipe 4 and the center exhaust pipe 5 are respectively provided with a front catalyst and a rear catalyst. Exhaust gas and exhaust noise discharged from the engine passes through the exhaust pipes 4 to 6 and is purified to a predetermined degree when passing through the catalyst, and is also silenced and discharged to the outside when passing through the muffler 7b. Is done.

  Further, hooks 6a and 7c are projected from the rear exhaust pipe 6 and the muffler 7b of the exhaust system 3, and the hooks 6a and 7c are fixed to the lower side of the vehicle body floor 2 (not shown). ) Via a hanger rubber 8. Further, the upstream side of the center exhaust pipe 5 is suspended by a floor bracket 11 fixed to the lower side of the vehicle body floor 2 via a pair of left and right first and second hanger rubbers 9 and 10.

  As shown in FIG. 2, the floor bracket 11 has a tunnel portion 11a straddling the center exhaust pipe 5, and upper hanger hooks 11b are projected from both sides of the tunnel portion 11a. Also, a hanger stay 12 is fixed to the lower portion of the center exhaust pipe 5. The hanger stay 12 extends left and right with the center exhaust pipe 5 as a center, and lower hanger hooks 12 a project from both ends of the hanger stay 12.

  The upper hanger hook 11 b and the lower hanger hook 12 a are connected via first and second hanger rubbers 9 and 10. The first and second hanger rubbers 9 and 10 have substantially the same shape, and the hanger rubbers 9 and 10 are respectively provided with hook holes 9a and 10a for engaging the upper hanger hook 11b and the lower hanger hook 12a. ing.

  The upper hanger hook 11b is provided at a position inclined outward by a predetermined angle (for example, 40 °) with respect to a vertical axis passing through the center of the lower hanger hook 12a. Accordingly, when the hook holes 9a and 10a of the first and second hanger rubbers 9 and 10 are engaged with the upper hanger hook 11b and the lower hanger hook 12a, the first and second hanger rubbers 9 and 10 have a reverse C shape, When vertical vibration, left-right vibration, and composite vibration thereof are generated in the center exhaust pipe 5, these vibrations can be efficiently absorbed by elastic deformation of the first and second hanger rubbers 9 and 10.

  The first hanger rubber 9 is made of a material mainly composed of EPDM (ethylene propylene diene rubber) rubber, while the second hanger rubber 10 is made of a material mainly composed of silicon rubber.

  EPDM rubber and silicon rubber have different characteristics. First, as shown in FIG. 3 (a), the elastic modulus of the EPDM rubber indicated by the wavy line is significantly higher than that of the silicon rubber indicated by the thick line below the room temperature range (approximately 25 [° C.]). For this reason, for example, if an EPDM rubber and a hanger rubber made of silicon rubber having substantially the same elastic modulus in the vicinity of 25 [° C.] are disposed, the elastic modulus of the EPDM rubber is relatively low in a low temperature range of 25 [° C.] or lower. Increases, while silicon rubber decreases.

  Therefore, below normal temperature, silicon rubber can absorb a relatively low frequency compared to EPDM rubber, and the first hanger rubber 9 and EP rubber are the main components. By supporting the left and right sides of the center exhaust pipe 5 with the second hanger rubber 10 as described above, the vibration suppression frequency band is widened, and good vibration suppression performance can be obtained not only on rough roads but also at low to high speeds. it can. Incidentally, as shown by the thin line in FIG. 5A, when the hardness of the silicon rubber is lowered to a value that exhibits almost the same characteristic as the elastic modulus of the EPDM rubber in the high temperature range, the vibration suppression frequency band in the low temperature range becomes more. It becomes wider and better vibration damping can be obtained.

  As shown in FIG. 2B, the tensile strength of EPDM rubber is higher than that of silicon rubber at room temperature, but the tensile strength of EPDM rubber gradually decreases as it moves to a higher temperature. On the other hand, silicone rubber does not drop as much as the tensile strength decreases slightly as the temperature rises, and the tensile strength between EPDM rubber and silicone rubber is reversed at high temperatures.

  As a result, although the durability against the tensile strength of the EPDM rubber having a high tensile strength is high in the normal temperature range, the durability against the tensile strength of the silicon rubber is relatively high at the high temperature range. The two-hanger rubber 10 indicates a substantially different degree of progress of durability in all temperature ranges. Accordingly, the durability against the tensile strength does not decrease at the same time, and even if one of the hanger rubbers 9 and 10 is damaged, the support state of the center exhaust pipe 5 can be maintained by the other.

  In terms of tear strength, silicon rubber has lower characteristics than EPDM rubber. Therefore, when the silicon rubber and the EPDM rubber are damaged by external force, the silicone rubber, which is inferior in durability against tearing strength, has a higher degree of breakage than the EPDM rubber. Even if the hanger rubber 10 is broken, the support state of the center exhaust pipe 5 can be maintained by the first hanger rubber 9 mainly composed of EPDM rubber.

  Thus, according to this embodiment, the left and right sides of the center exhaust pipe 5 are supported by the first hanger rubber 9 mainly composed of EPDM rubber and the second hanger rubber 10 mainly composed of silicon rubber. Therefore, both the hanger rubbers 9 and 10 exhibit different characteristics in terms of elastic modulus, tensile strength, tear strength, and the like. As a result, the center exhaust pipe 5 is supported by both the hanger rubbers 9 and 10 so that the running conditions and temperature conditions are increased. Below, excellent durability can be obtained, and it can fully meet the demands of recent high performance vehicles. In addition, since the degree of progress of the lowering of the durability of both the hanger rubbers 9 and 10 is made different, the both hanger rubbers 9 and 10 do not fall off at the same time, and therefore measures to prevent the hanger rubbers 9 and 10 from coming off at the same time. Is eliminated, and the product cost can be reduced accordingly.

  Further, since the characteristics are changed depending on the material of both the hanger rubbers 9 and 10, the shapes of both the hanger rubbers 9 and 10 do not need to be complicated, and may be the same shape. Can be manufactured.

  The present invention is not limited to the above-described embodiment. For example, the exhaust system members that support the left and right with a pair of hanger rubbers 9 and 10 are not limited to the center exhaust pipe 5, but the rear exhaust pipe 6 and the muffler portion 7. It may be.

1 ... the car body,
2 ... body floor,
3 ... exhaust system,
4 ... Front exhaust pipe,
5 ... Center exhaust pipe,
6 ... Rear exhaust pipe,
6a, 7c ... hook 7 ... muffler part,
7a ... Muffler tube,
7b ... Muffler,
8 ... Hanger rubber,
9 ... 1st hanger rubber,
9a, 10a ... hook holes,
10 ... Second hanger rubber,
11 ... Floor bracket,
11a ... Tunnel part,
11b ... Upper hanger hook,
12 ... Hanguestay,
12a ... Lower hanger hook

Claims (7)

In an exhaust system support structure comprising a pair of first and second hanger rubbers for suspending an exhaust system member on a vehicle body frame,
The exhaust system support structure, wherein the first hanger rubber and the second hanger rubber have a plurality of different characteristics.   The exhaust system support structure according to claim 1, wherein the plurality of different characteristics include tensile strength and tear strength. 3. The exhaust according to claim 1, wherein the tensile strength of the first hanger rubber is higher than that of the second hanger rubber in a normal temperature region, and the second hanger rubber is higher than that of the first hanger rubber in a high temperature region. System support structure. The exhaust system support structure according to any one of claims 1 to 3, wherein the tear strength of the first hanger rubber is higher than that of the second hanger rubber. The exhaust system support structure according to any one of claims 1 to 4, wherein the first hanger rubber contains ethylene, propylene, and diene rubber as main components. The exhaust system support structure according to any one of claims 1 to 5, wherein the second hanger rubber includes silicon rubber as a main component.   The exhaust system support structure according to claim 1 or 2, wherein the first hanger rubber and the second hanger rubber have relatively different elastic coefficient changes with respect to temperature changes, particularly in a temperature range of room temperature or lower.

Images