Exhaust muffler support structure

Abstract

To suppress motion accompanying an inertial force applied on an exhaust muffler without limiting freedom of laying out the exhaust muffler and designing a vehicle body.SOLUTION: An exhaust muffler support structure comprises: a pair of left and right vehicle body side hanger stays 7; a pair of left and right muffler side hanger stays 6; and cushion rubbers 8. The vehicle body side hanger stays 7 extend from a vehicle body bottom. The muffler side hanger stays 6 are fixed to a muffler body 2. The cushion rubbers 8 have hook holes 8a and 8b formed on both sides in a main axis direction so as to penetrate suspension hooks 7a formed in the vehicle body side hanger stays 7 and suspended hooks 6a formed in the muffler side hanger stays 6. An elastic main axis X calculated from characteristics of the left and right cushion rubbers 8 is set on the gravity center position W of the muffler body.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to an exhaust muffler support structure that supports an exhaust muffler on a vehicle body frame via a cushion member. [Background technology]

[0002] Conventionally, in vehicles such as automobiles, exhaust system components such as exhaust pipes and mufflers are supported on the bottom of the vehicle body by hanging them from the underside of the vehicle floor via cushioning members, thereby reducing the vibration and shaking of the exhaust system and suppressing the transmission of vibration to the vehicle body.In order to efficiently block the transmission of vibration to the vehicle body, it is advantageous to set the spring constant of the cushioning member low (to make it soft).

[0003] When changing lanes or traveling on a road with many curves, the lateral movement of the vehicle causes an inertial force to act on the exhaust system, but if the spring constant is low, the exhaust system is more likely to be subjected to the inertial force and swing outward. As a result, a delay occurs in the lateral movement acting on the exhaust muffler relative to the vehicle, resulting in poor response and affecting vehicle behavior due to the vibration of the exhaust muffler.

[0004] As a countermeasure to this problem, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-160536) discloses a technology in which a muffler-side hanger attached to the exhaust muffler and a vehicle-side hanger that suspends this muffler-side hanger via a cushion member are supported at the center of gravity of the exhaust muffler. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-160536 Summary of the Invention [Problem to be solved by the invention]

[0006] In the exhaust muffler suspension structure disclosed in the above-mentioned document, the exhaust muffler is supported at its center of gravity, providing good support balance and making it possible to restrict the movement of the exhaust muffler.

[0007] However, with this technology, the attachment positions of the muffler-side hanger and the vehicle-side hanger are determined based on the center of gravity of the exhaust muffler, which limits the degree of freedom in layout of the exhaust muffler relative to the vehicle.Also, conversely, if priority is given to the layout of the exhaust muffler, the degree of freedom in designing the vehicle itself is limited.

[0008] The present invention aims to provide an exhaust muffler support structure that can suppress vibrations caused by inertial forces acting on the exhaust muffler without restricting the freedom of exhaust muffler layout and vehicle body design. [Means for solving the problem]

[0009] The present invention provides an exhaust muffler support structure including a pair of left and right vehicle body side hangers extending from the bottom of the vehicle body, a pair of left and right muffler side hangers fixed to an exhaust system main body, a hanging hook portion formed on each of the vehicle body side hangers, a suspended hook portion formed on each of the muffler side hangers, and a cushion member having a hook hole for insertion into the hanging hook portion and another hook hole for insertion into the suspended hook portion on both sides in the main axis direction, wherein the elastic main axis determined from the characteristics of the left and right cushion members is set on the center of gravity of the exhaust system main body. The main elastic axis is set parallel to the base of an isosceles triangle having equilateral sides defined by extensions of the inclinations of the main axes of the left and right cushion members, and the distance from the point of intersection of the main elastic axis with a line perpendicular to the base and a line connecting the other hook holes formed on the left and right cushion members to the main elastic axis is expressed as follows: Ha is the spring constant in the main axis direction, kp is the spring constant in the shear direction, kq is the spring constant in the shear direction, y2 is half the length of the distance between the other hook holes, and α is the base angle of the isosceles triangle. Ha=(kp-kq)·y2·sinα·cosα / (kp·cos 2 α+kq·cos 2 α) Search from . [Effects of the Invention]

[0010] According to the present invention, the principal axis of elasticity determined from the characteristics of the left and right cushion members is set at the center of gravity of the exhaust system main body, so that vibrations caused by inertial forces acting on the exhaust muffler can be suppressed without restricting the degree of freedom in exhaust muffler layout and vehicle body design. [Brief explanation of the drawings]

[0011] [Figure 1] A plan view showing the support structure of the exhaust muffler [Figure 2] A side view showing the support structure of the exhaust muffler [Figure 3] Front view of cushion rubber [Figure 4A] An explanatory diagram modeling the exhaust muffler support structure for the first example [Figure 4B] An explanatory diagram modeling the exhaust muffler support structure for the second example [Figure 4C] Explanatory diagram modeling the exhaust muffler support structure in the third example [Figure 4D] Explanatory diagram modeling the exhaust muffler support structure for the fourth example [Figure 4E] Illustrative diagram of the exhaust muffler support structure modeled in the fifth example DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 in Figures 1 and 2 denotes an exhaust muffler, which is disposed at the rear end of an exhaust system that extends from an engine mounted at the front of a vehicle, through the bottom of the vehicle, and to the rear of the vehicle. A muffler pipe 3 provided in the exhaust system is connected to a front end surface 2a (exhaust gas inflow side) of a muffler body 2 serving as the exhaust system main body provided in the exhaust muffler 1.

[0013] A tail pipe 4 is connected to a rear end surface 2b (exhaust gas outlet side) of the muffler body 2, and a muffler cutter 5 is attached to the rear end of the tail pipe.

[0014] Exhaust gas emitted from the engine passes through the exhaust system and flows into the muffler body 2 through the muffler pipe 3. As the exhaust gas passes through the muffler body 2, the exhaust noise in the exhaust gas is muted, and the muted exhaust gas flows out to the tailpipe 4 and is discharged to the outside through the muffler cutter 5. The muffler body 2 may have various cross-sectional shapes, such as a circular cross section, an elliptical cross section, or an approximately triangular cross section, depending on the vehicle on which it is installed.

[0015] A pair of left and right muffler side hanger stays 6 as muffler side hangers are provided on the rear end surface 2b of the muffler body 2. Since the muffler side hanger stays 6 have a substantially symmetrical shape, they will be denoted by the same reference numerals for convenience in explanation.

[0016] Each muffler side hanger stay 6 is a rod-shaped metal material, one end of which is bent into a shape that follows the upper edge of the rear end face 2b and joined by means of welding or the like. The other end of each muffler side hanger stay 6 extends diagonally downward and rearward from the rear end face 2b, and the other end is bent forward and extends to a position where it overlaps with the rear side surface of the muffler body 2, forming a substantially horizontal suspended hook portion 6a.

[0017] Furthermore, a pair of left and right vehicle body side hanger stays 7 formed into approximately the same shape as vehicle body side hangers are disposed above a position corresponding to the suspended hook portion 6a of the muffler side hanger stay 6. The vehicle body side hanger stay 7 is formed by bending a rod-shaped metal material, and one end is fixed by welding or other means to a floor bracket or floor cross member on the underside of the vehicle. Furthermore, the middle of the vehicle body side hanger stay 7 extends downward, and the other end is formed with a suspension hook portion 7a that is bent into an L shape toward the rear of the muffler body 2 in a state parallel to the suspended hook portion 6a of the muffler side hanger stay 6.

[0018] The suspended hook portion 6a of the muffler-side hanger stay 6 and the opposing suspending hook portion 7a of the vehicle-body-side hanger stay 7 are connected via a cushion rubber 8 serving as a cushion member. As shown in FIG. 3 , the cushion rubber 8 is oval-shaped, with its major axis along its long axis. On both sides of the major axis, there are formed hook holes 8a as other hook portions into which the suspended hook portion 6a of the muffler-side hanger stay 6 is inserted, and hook holes 8b into which the suspending hook portion 7a of the vehicle-body-side hanger stay 7 is inserted. Furthermore, a generally H-shaped hollow portion 8c is formed in the center of the cushion rubber 8. This hollow portion 8c adjusts the mobility of the cushion rubber 8. Although not shown, the muffler pipe 3 connected to the front side of the muffler main body 2 is supported on the bottom of the vehicle body via another cushion rubber.

[0019] However, the shape and layout of the exhaust system differ from vehicle to vehicle, and therefore the shape of the exhaust muffler 1 and its mounting position on the vehicle also differ from vehicle to vehicle, making it difficult to always support the muffler body 2 at its center of gravity W, which is the main inertial body of the muffler body 2, as in the conventional technology described above, due to layout restrictions.

[0020] Therefore, in this embodiment, the characteristics and mounting position of the cushion rubber 8 are set so that the muffler body 2 can be supported at a position that best limits vibrations caused by inertial forces, while being subject to layout constraints.

[0021] That is, the muffler body 2 is suspended from the underside of the vehicle body by inserting the hook holes 8a, 8b of the cushion rubber 8 into the suspended hooks 6a of the muffler-side hanger stays 6 provided on the left and right and the suspension hook portions 7a of the vehicle-body-side hanger stays 7, respectively. Then, the principal elastic axis X in the load (lateral G) direction, which is determined by the characteristics of the left and right cushion rubbers 8 at that time, is adjusted so that it passes through the center of gravity W of the muffler body 2 when viewed from the front (or rear). The "principal elastic axis X" here refers to an imaginary axis in which the direction in which the load (lateral G) acts on the muffler body 2 and the direction in which the muffler body 2 is displaced by the elastic deformation of the cushion rubber 8 coincide, and in which no angular displacement occurs.

[0022] Therefore, by setting the principal elastic axis at the center of gravity W, which is the main inertial force of the muffler body 2, the left and right cushion rubbers 8 can support the muffler body 2 in a well-balanced manner, suppressing rotational vibration caused by the moment when inertial force acts on the muffler body 2 from the lateral direction. As a result, the muffler body 2 has better response when lateral acceleration occurs while the vehicle is running, reducing the impact on vehicle behavior.

[0023] Below, we will show examples of adjusting the positional relationship between the muffler body 2 and the left and right cushion rubbers 8 so that the main elastic axis X passes through the center of gravity W of the muffler body 2. In all examples, the muffler body 2 is supported in a nearly horizontal state on the bottom of the vehicle body. The support structure of the muffler body 2 is also the same. Furthermore, the main axes of the left and right cushion rubbers 8 are inclined in different directions. [First response example] Figure 4A shows a model of the support positions when the muffler body 2 shown in Figures 1 and 2 is suspended. In this example, the muffler body 2 is supported at symmetrical positions by a pair of hanger stays 6, 7 and cushion rubbers 8. In this example, the center of gravity W of the muffler body 2 is below the line connecting the hook holes 8a of the left and right cushion rubbers 8. The main axes of both cushion rubbers 8 are symmetrical and are inclined at an angle such that their lower ends intersect.

[0024] In this example, if the center of gravity position W of the muffler body 2, the distance between the cushion rubbers 8, and the inclination of the main axis are predetermined, first draw an inverted isosceles triangle with the lines connecting the main axes of the left and right cushion rubbers 8 as equilaterals and the line connecting the centers of the hook holes 8a on the muffler side as the base, and then determine the length of the base and the base angle α.

[0025] Next, the principal elastic axis X is set at a position that passes through the center of gravity W and is parallel to the base, and the distance Ha from this principal elastic axis X to the base is found. Then, the spring constant kp of the cushion rubber 8 in the principal axis direction and the spring constant kq in the shear direction perpendicular to this are calculated from the following equation (1). Ha=(kp-kq)·y2·sinα·cosα / (kp·cos 2 α+kq·cos 2 α) …(1) Here, y2 is half the length of the base.

[0026] As a result, the direction of the load (lateral G) acting on the muffler body 2 coincides with the direction of displacement of the muffler body 2 due to the elastic deformation of the cushion rubber 8, thereby reducing the moment when an inertial force acts on the muffler body 2 and suppressing rotational vibration of the muffler body 2 itself.

[0027] In this example and the second to fifth examples described later, the apex angle does not need to be a right angle. The center of gravity W may be located on the main elastic axis X, but as shown in the drawings, if it is set at a position perpendicular to the main elastic axis X at half the line connecting the left and right hook holes 8a, the muffler body 2 can be supported in a more balanced manner. [Second example of response] Figure 4B shows a second example of the muffler body 2. In this example, the center of gravity W of the muffler body 2 is set above the line connecting the hook holes 8a of the left and right cushion rubbers 8, and the extensions of the main axes of the cushion rubbers 8 are tilted in directions that intersect above, in contrast to the first example of the muffler body 2 shown in Figure 4A.

[0028] In this case, as in the first modified example described above, if the center of gravity W of the muffler body 2, the distance between the cushion rubbers 8, and the inclination of the main axis are predetermined, first an isosceles triangle is drawn with equal sides defined by lines extending and connecting the main axes of the left and right cushion rubbers 8 and the line connecting the centers of the hook holes 8a on the muffler side as the base, and the length of the base and the base angle α are determined. The spring constants kp and kq of the cushion rubbers 8 are set based on the distance Ha from the main elastic axis X, which passes through the center of gravity W, to the base. [Third example of response] A third example of the correspondence is shown in Figure 4C. As shown in the figure, if the inclination and position of the left and right cushion rubbers 8 are different, when drawing based on the line connecting the centers of the hook holes 8a of the left and right cushion rubbers 8 and the inclination of the main axis, the line connecting the centers of the hook holes 8a may not be the base of an isosceles triangle. In this example, the center of gravity W of the muffler body 2 is below the line connecting the hook holes 8a of the left and right cushion rubbers 8.

[0029] In such a case, first, extend the main axes of the left and right cushion rubbers 8 and intersect them at the apex angle, then draw an isosceles triangle with the longer side being the equilateral line from the apex angle to the hook holes 8a of the cushion rubbers 8, and find the hook distance and base angle α on the base between the left and right hook holes 8a. Next, draw the main elastic axis X that is parallel to the base of this isosceles triangle and passes through the center of gravity W.

[0030] Also, a perpendicular line is drawn from a position y2 on the base that is half the length of the distance between the left and right hook holes 8a to the elastic principal axis X. Then, the distance Ha from the intersection P of the perpendicular line and the line connecting the hook holes 8a of the left and right cushion rubbers 8 to the elastic principal axis X is found, and the spring constants kp and kq of the cushion rubber 8 are set from equation (1). [Example of response No. 4] Figure 4D shows a fourth example. As with the third example, this example shows a case where the inclination and position of the left and right cushion rubbers 8 are different, so the line connecting the centers of the hook holes 8a does not form the base of an isosceles triangle. In this example, the center of gravity W of the muffler body 2 is above the line connecting the hook holes 8a of the left and right cushion rubbers 8.

[0031] In such a case, first, extend the main axes of the left and right cushion rubbers 8 and intersect them at the apex angle, draw an isosceles triangle with the longer of the lines connecting the apex angle to the hook holes 8a of the cushion rubbers 8 as the equilateral sides, and then find the base angle α and the distance between the left and right hook holes 8a on the base. Next, draw the main elastic axis X that is parallel to the base of this isosceles triangle and passes through the center of gravity W.

[0032] Then, draw a perpendicular line from half the distance between the left and right hook holes 8 on the base side to the main elastic axis X, and find the distance Ha from the intersection P of the perpendicular line and the line connecting the hook holes 8a of the left and right cushion rubbers 8 to the main elastic axis X, and set the spring constants kp and kq of the cushion rubber 8 from equation (1). [5th response example] 4E shows a fifth example of the correspondence. Even if the line connecting the hook holes 8a of the left and right cushion rubbers 8 is horizontal, if the inclinations and positions of the left and right cushion rubbers 8 are different when calculating the distance Ha to the principal elastic axis X, the base of the isosceles triangle is not necessarily horizontal. In this example, the center of gravity W of the muffler body 2 is above the line connecting the hook holes 8a of the left and right cushion rubbers 8.

[0033] In such a case, first, extend the main axes of the left and right cushion rubbers 8 and intersect them at the apex angle, draw an isosceles triangle with the longer of the lines connecting the apex angle to the hook holes 8a of the cushion rubbers 8 as the equilateral sides, and then find the base angle α and the distance between the left and right hook holes 8a on the base. Next, draw the main elastic axis X that is parallel to the base of this isosceles triangle and passes through the center of gravity W.

[0034] Then, a perpendicular line is drawn from half the distance between the left and right hook holes 8 on the base side to the main elastic axis X, and the distance Ha from the intersection P of the perpendicular line and the line connecting the hook holes 8a of the left and right cushion rubbers 8 to the main elastic axis X is found, and the spring constants kp and kq of the cushion rubbers 8 are set from equation (1).

[0035] In this embodiment, since the main elastic axis X is inclined, when lateral G acts on the muffler body 2, an inertial force is generated in the muffler body 2 in the diagonal direction along the main elastic axis X, but the moment in the rotational direction is small, so that rotational vibration can be suppressed.

[0036] As described above, in this embodiment, the characteristics of the left and right cushion rubbers 8 are set based on equation (1) so that the main elastic axis X passes through the center of gravity position W of the muffler body 2. Therefore, the direction of the force applied from the muffler body 2 in the main axial direction and shear direction of the cushion rubbers 8 can be made to coincide with the direction of elastic displacement of the cushion rubbers 8 without restricting the degree of freedom in the layout of the exhaust muffler 1 and the vehicle body design.

[0037] As a result, the inertial force of the muffler body 2 is suppressed, reducing the impact on vehicle behavior when changing lanes or traveling on roads with many curves, resulting in good driving performance. Also, the spring constant of the cushion rubber 8 can be made relatively low, effectively blocking the transmission of vibrations to the vehicle body.

[0038] The present invention is not limited to the above-described embodiment. For example, the muffler side hanger stay 6 may be fixed to the front end surface 2 a of the muffler body 2 .

[0039] Furthermore, in the above-described corresponding examples, the spring constants kp and kq included in equation (1) are described as unknowns. However, the other elements Ha, y2, and α may be used as unknowns to set the principal elastic axis X passing through the center of gravity position W. [Explanation of symbols]

[0040] 1...Exhaust muffler, 2...Muffler body, 2a...front end surface, 2b...rear end surface, 3...Muffler pipe, 4...Tailpipe, 5...Muffler cutter, 6... Muffler side hanger stay, 6a...Hanging hook part, 7...Car body side hanger stay, 7a...Hanging hook part, 8...Cushion rubber, 8a, 8b...Hook holes, 8c...Hollow part, kp, kq...spring constants, Ha...distance (to the principal axis of elasticity) P...intersection, X: elastic axis, W...center of gravity position, α…base angle

Claims

1. a pair of left and right vehicle body side hangers extending from the bottom of the vehicle body; A pair of left and right muffler side hangers fixed to the exhaust system main body; a hanging hook portion formed on each of the vehicle body side hangers; A hanging hook portion formed on each muffler side hanger; a cushion member having a hook hole for inserting the suspending hook portion and another hook hole for inserting the suspended hook portion on both sides in the main axis direction; In an exhaust muffler support structure comprising: A main axis of elasticity determined from the characteristics of the left and right cushion members is set on the center of gravity of the exhaust system main body, the main elastic axis is set parallel to a base when an isosceles triangle is set with equal sides being extensions of the inclinations of the main axes of the left and right cushion members, The distance from the point of intersection of a line that is perpendicular to the base and intersects the main elastic axis with a line that connects the other hook holes formed in the left and right cushion members to the main elastic axis is expressed as follows: Ha is the distance, kp is the spring constant in the main axis direction, kq is the spring constant in the shear direction, y2 is half the length of the distance between the other hook holes, and α is the base angle of the isosceles triangle. Ha=(kp-kq)・y2・sinα・cosα / (kp・cos 2 α+kq・cos 2 α) Search from An exhaust muffler support structure characterized by:

2. The characteristics of the cushion member are specified by at least the spring constants in the main axis direction and the shear direction perpendicular to the main axis direction.

2. The exhaust muffler support structure according to claim 1.

3. The characteristics of the cushion members are specified by at least the inclination angles of the cushion members on the left and right sides of the center of gravity in the direction of the main axis.

3. The exhaust muffler support structure according to claim 1 or 2.

4. The characteristics of the cushion member are specified by at least the distance between the other hook holes formed on the left and right cushion members.

4. The exhaust muffler support structure according to claim 1, wherein the exhaust muffler support structure is a support structure for supporting an exhaust muffler.

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