JP2000006673A - Dynamic damper for exhaust pipe of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic damper without losing vibration reduction effect by the heat of an exhaust pipe. SOLUTION: A support plate 2 is formed by folding one metallic sheet, and one end part and the other end part of the metallic sheet with a folded part 21 therebetween are made a base sheet part 22 and a holding sheet part 23. The base sheet part 22 is fixed to a flange part F of an exhaust pipe P so that the holding sheet part 23 is extended horizontally along an outer circumferential surface on a lower side of the exhaust pipe P. An inertia body is mounted on a tip part of the holding sheet part 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic damper for reducing a vibration near a natural frequency of an exhaust pipe of a vehicle.

[0002]

2. Description of the Related Art Generally, an exhaust pipe of a vehicle vibrates under the influence of an engine. In particular, it vibrates greatly near the natural frequency. When the exhaust pipe vibrates greatly, the vibration propagates into the vehicle via a bracket or the like that supports the exhaust pipe, and generates a so-called muffled sound that gives an occupant a discomfort. Therefore,
The exhaust pipe of the vehicle is provided with a dynamic damper for reducing vibration near the natural frequency.

A conventional dynamic damper is referred to as a main body attached to an exhaust pipe, a rubber holding member having a base end attached to the main body, and a normal mass attached to a distal end of the holding member. The inertial body is configured to reduce vibration near the natural frequency of the exhaust pipe by appropriately selecting the length and elastic modulus of the holding member, the mass of the inertial body, and the like. .

[0004]

In the above-mentioned conventional dynamic damper, since the holding member is made of rubber, a high temperature (about 200 to 300 ° C.) is required by the exhaust pipe.
However, there is a problem in that the exhaust pipe is softened when heated, and the vibration reducing action at the natural frequency of the exhaust pipe cannot be obtained.
In addition, there is a problem that the holding member is deteriorated by heat, and the vibration reducing action is lost at an early stage. Therefore, a heat shield cover is interposed between the exhaust pipe and the holding member. However, in such a case, the number of parts and the time and labor for installation are increased by the heat shield cover, and the manufacturing cost is increased. Another problem arises.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a substrate portion having a base portion provided with a mounting portion to be mounted on an exhaust pipe, and a distal end of the substrate portion. A metal L-shaped support plate having a holding plate portion extending in a direction substantially perpendicular to the substrate portion from the portion, and an inertial body attached to the holding plate portion of the support plate. I have. In this case, the support plate is formed of a metal plate bent at a substantially right angle, and one end and the other end of the metal plate between the bent portions become the substrate portion and the holding plate portion, respectively. Is desirable.
Further, the mounting portions are provided on both sides of one end portion of the substrate portion, respectively, and have a pair of arm portions fixed to one side portion and the other side portion of the exhaust pipe, respectively. It is preferable that a concave portion is formed in the substrate portion between the arm portions, and an outer peripheral portion located between the pair of arm portions of the exhaust pipe is inserted into the concave portion.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2
Shows an embodiment of the present invention. Before describing the dynamic damper 1 of this embodiment, first, an exhaust pipe P on which the dynamic damper 1 is installed will be described. The exhaust pipe P is configured by connecting a plurality of pipe members Pa to each other. Each of the pipe members Pa has a flange portion F formed at each end thereof butted against each other, and is fixed with a bolt B and a nut N.
The exhaust pipe P has one end connected to an exhaust port of an engine (not shown), the other end extending along a lower portion of a vehicle frame (not shown) to a rear end thereof, and has a longitudinal direction. Are supported by the frame in a suspended state by brackets (not shown).

The exhaust pipe P vibrates in the vertical and horizontal directions and in the front-back direction. However, when the exhaust pipe P is supported in a suspended state as in this embodiment, the vertical vibration becomes a problem. This is because the vibrations in the left-right and front-back directions are absorbed by the bracket being appropriately elastically deformed, and are hardly transmitted from the exhaust pipe P to the frame. When the dynamic damper 1 is installed in the exhaust pipe P, the dynamic damper 1 should be installed in a portion having the largest amplitude. In this embodiment, the flange portion F vibrates the most.
Therefore, the dynamic damper 1 is fixed to the flange portion F.

Next, the dynamic damper 1 will be described. The dynamic damper 1 has a support plate 2. The support plate 2 is formed by bending a plate material made of a metal such as stainless steel at a right angle.
One end portion between them is a substrate portion 22 extending in the vertical direction, and the other end portion is a holding plate portion 23 extending in the horizontal direction.

A pair of arms 24, 24 extending in an arc shape are formed on both sides of the upper end of the substrate portion 22, respectively. A semicircular recess 25 is formed at the upper end of the substrate 22 located between the arms 24. The radius of curvature of the concave portion 25 is slightly larger than the radius of the pipe member Pa. Therefore, the center of curvature of the concave portion 25 and the pipe member P
By inserting the pipe member Pa into the concave portion 25 until the center of the pipe member Pa coincides with the center of the arm portion 2, a slight gap can be formed between the inner peripheral surface of the concave portion 25 and the outer peripheral surface of the pipe member Pa.
4, 24 extend along the pipe member Pa while being slightly away from the outer peripheral surface thereof. In addition, an insertion hole 24 a is formed at the tip of each arm 24. This insertion hole 2
The bolt B is inserted through 4a. By tightening the bolt B and the nut N, the arm 24
Are pressed and fixed to the flange portion F, and the flange portions F and F are pressed and fixed to each other.

The holding plate portion 23 extends horizontally along the lower side of the outer peripheral surface of the exhaust pipe P, and a metal inertia member 3 usually called a mass is fixed to a tip portion thereof. I have. Therefore, when the exhaust pipe P vibrates up and down, the holding plate 23
Vibrates so as to swing up and down around the bent portion 21. Here, the weight W of the inertia body 3, the distance L between the center of gravity G of the inertia body 3 and the bent portion 21, the thickness t of the holding plate 23, and the like, determine the vibration at the natural frequency of the exhaust pipe P, It is determined based on experiments so as to be able to reduce the frequency by dispersing it to frequencies higher and lower than the natural frequency.

Therefore, when the dynamic damper 1 is attached to the exhaust pipe P, the vibration at the natural frequency f ₀ of the exhaust pipe P can be reduced as shown in FIG. Needless to say, the exhaust pipe P is controlled by the frequencies f ₁ and f ₂ on both sides of the natural frequency f _0.
Will oscillate relatively large, but its amplitude is much smaller than the amplitude at the natural frequency.

In the dynamic damper 1 having the above-described structure, no rubber holding member is used, and the holding plate 23 for supporting the inertial body 3 is made of metal.
Even if 3 is heated to about 300 ° C. by the exhaust pipe P, it hardly softens. Therefore, even if heated to a high temperature, the desired vibration reduction effect can be sufficiently exhibited. In addition, since the holding plate 23 does not deteriorate over time due to heat, the vibration reducing effect can be maintained semi-permanently. Further, since there is no need to install a heat shield cover, the number of parts can be reduced by that much, and the labor for installation can be reduced.

In particular, in the dynamic damper 1 of this embodiment, since the support plate 2 is formed by bending a single metal plate, it can be manufactured at low cost. Further, since the concave portion 25 is formed in the substrate portion 22 and the lower portion of the exhaust pipe P is inserted through the concave portion 25, the holding plate portion 23 can be brought close to the exhaust pipe P. Therefore, the space occupied by the dynamic damper 1 can be reduced.

Next, another embodiment of the present invention shown in FIGS. 4 and 5 will be described. In the dynamic damper 1 ′ of this embodiment, the arms 24 are twisted by approximately 90 ° so that the upper ends of the arms 24 are parallel to the exhaust pipe P. Each has a contact portion 24b having the same radius of curvature as the outer peripheral surface of the exhaust pipe P. The support plate 2 is fixed to the exhaust pipe P by welding the contact portion 24b in a state where the contact portion 24b is in contact with the outer peripheral surface of the central portion in the vertical direction of the exhaust pipe P. Other configurations are the same as in the above embodiment.

The present invention is not limited to the above embodiment, but can be modified as appropriate. For example, in the above-described embodiment, the vertical vibration of the exhaust pipe P has been considered as a problem. Therefore, the holding plate 23 is disposed below the exhaust pipe P. However, the horizontal vibration of the exhaust pipe P is a problem. In this case, the holding plate portion 23 may be disposed on the left or right side of the exhaust pipe P in parallel with the exhaust pipe P.

[0016]

As described above, according to the first aspect of the present invention, it is possible not only to prevent the vibration reducing effect from being reduced by the heat of the exhaust pipe, but also to reduce the vibration reducing effect semipermanently. The advantage is that the maintenance cost can be maintained and the manufacturing cost and installation time can be reduced. According to the second aspect of the invention, an effect is obtained that the manufacturing cost can be further reduced. According to the third aspect of the invention, an effect is obtained that the space occupied by the dynamic damper can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a diagram showing the relationship between the frequency of the exhaust pipe and the sound pressure level in the vehicle when a dynamic damper is attached to the exhaust pipe and when it is not attached.

FIG. 4 is a side view showing another embodiment of the present invention.

FIG. 5 is a sectional view taken along line XX of FIG. 4;

[Explanation of symbols]

 P Exhaust pipe 1 Dynamic damper 1 'Dynamic damper 2 Support plate 3 Inertial body 21 Bent part 22 Substrate part 23 Holding plate part 24 Arm part 25 Depression

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuya Sugimoto 292 Bessho-cho, Ota-shi, Gunma Sakamoto Kogyo Co., Ltd. F-term (reference) 3D038 BA02 BA06 BA07 BA13 BB01 BC07 BC24 3G004 AA01 BA04 DA21 EA05 EA06 GA01 3J048 AA06 AD06 BF05 CB22 EA30

Claims (3)

[Claims] 1. A metal L-shape having a substrate portion provided with a mounting portion attached to an exhaust pipe at a base end portion, and a holding plate portion extending from a distal end portion of the substrate portion in a direction substantially orthogonal to the substrate portion. A dynamic damper for an exhaust pipe of a vehicle, comprising: a supporting plate having a shape; and an inertial body attached to a holding plate portion of the supporting plate. 2. The method according to claim 1, wherein the support plate is formed of a metal plate bent at a substantially right angle, and one end and the other end of the metal plate between the bent portions are respectively connected to the substrate and the holding plate. The dynamic damper for an exhaust pipe of a vehicle according to claim 1, wherein 3. The mounting portion has a pair of arms provided on both sides of one end of the substrate portion and fixed to one side and the other side of the exhaust pipe, respectively. The concave portion is formed in the substrate portion between the pair of arms, and an outer peripheral portion of the exhaust pipe located between the pair of arms is inserted into the concave portion. Dynamic damper for exhaust pipes of vehicles.