JP2001138842A - Dynamic damper structure of bumper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure having durability, simple structure and no possibility that a bumper slips off during normal running by fitting the bumper through a rubber bushing to the car body side to optimize a spring constant of a fitting part as a dynamic damper to idling vibration. SOLUTION: A bush 1 is formed cylindrically to clamp a rubber 1b between an outer sleeve 1a and an inner sleeve 1c. The inner sleeve 1c and the outer sleeve 1a are formed of a material with high rigidity and tensile force such as steel material or the like. Since the inner sleeve 1c is longer than the outer sleeve 1a, the inner sleeve 1c is strongly clamped and stopped between a bumper bracket 3 and a washer 1d by a bolt 1e. The outer sleeve 1a is firmly fixed to the bumper bracket 3. An upper gap 1b is secured between the bumper bracket 3 and a bumper reinforced part 2a, and a gap 1h is secured between the bumper bracket 3 and the washer 1d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of a dynamic damper structure of a bumper using a rubber bush as an elastic body.

[0002]

2. Description of the Related Art FIG. 15 is a perspective view showing a three-dimensional appearance of a mounting structure of a front bumper of a vehicle. A part of the bumper 2 is fixed to the chassis 4 via a bumper bracket 3 and has a structure for transmitting an impact force applied to the bumper to the chassis. In a monocoque car, there is no chassis, so the bumper is attached to a part of the body where rigidity is increased. FIG. 14 shows the structure of a bumper mounting portion in the prior art.
The GG section of the F portion of No. 5 is shown. The reinforcing material 2a inside the bumper 2 is directly fastened to the bumper bracket 3 with bolts 1e. The bumper bracket 3 is fastened to the chassis 4 in FIG.

[0003] As a countermeasure against the vibration of the vehicle, a countermeasure when the engine is loaded is given priority. Therefore, a countermeasure is taken for the engine drive system itself so that dangerous vibration does not occur when the engine rotates at a high speed. For this reason, there is little room for countermeasures in the engine drive system itself for low engine idling rotation. Therefore, a body structure must be solved as a measure against body vibration during idling, but since the body itself is designed with priority given to collision safety, habitability, appearance, etc., changes in the body structure are limited due to these conditions. Receive.

In the case where the bumper and the body as shown in FIG. 14 are integrally formed via a chassis, these are mechanically simplified so that a simple structure on a vehicle suspension using the idling rotation of the engine as an exciting force is obtained. If it is treated as a simple vibration system, as shown in FIG. 12 or FIG. 13, it is composed of the total mass of the body 9 and the bumper 2 directly connected to the body 9 and their spring stiffness 9a. To solve the problem with the body structure as a measure against body vibration, the total mass of the body 9 and the bumper 2 directly connected to the body 9 and the spring rigidity 9a must be adjusted. Therefore, it means conflict with other priority design conditions in the body design. As shown in FIG. 13, when the mass of the bumper 2 is smaller than the mass of the body 9, even if the mass and rigidity of only the bumper 2 are adjusted to avoid a design change of the body 9, there is no effective countermeasure for idling vibration. . As shown in FIG.
12 is an important part of the exterior configuration of the body 9, the mass of the bumper 2 becomes larger than the mass of the body 9 as shown in FIG. However, if the structure of the bumper 2 is adjusted, it is more effective than the case of FIG. 13, but the method cannot be realized because the appearance cannot be sacrificed in practice.

[0005] As described above, it is necessary to take measures against vibration during engine idling without changing the basic structure of the bumper and the body. Therefore, as shown in FIG. It is conceivable to use a large bumper as a dynamic damper. As an example of a conventional technique using a bumper as a dynamic damper, a mounting structure of a bumper disclosed in Japanese Patent Application Laid-Open No. 6-40298 has been disclosed. In this example, the bumper is attached to the body by a bumper stay that functions as a leaf spring.The feature is that the bumper stay is made of a leaf spring. It is claimed that the spring constant is stable, durable, and can be a simple structure. However, in order to cope with a vibration source having a relatively low frequency and a low excitation force at the time of engine idling, the effect of the leaf spring portion cannot be improved unless the rigidity is considerably reduced. If the rigidity of the leaf spring bumper stays low, it is effective against vibration during engine idling, but it resonates with a stronger excitation force during idling due to road surface conditions during normal driving, and durability is poor The leaf spring bump pasty may be broken and the bumper may fall off. In order to avoid such a danger, it is necessary to set the rigidity of the leaf spring bump pasty to a considerably high level. It does not make sense. The structure is also quite complicated.

Another example of the prior art using a bumper as a dynamic damper is disclosed in Japanese Utility Model Publication No. Sho 62
Japanese Patent Application Laid-Open No. 6-40298 discloses a structure in which a bumper is attached to a body by a bump pasty functioning as a leaf spring in this example. Has the same problems as the structure.

[0007]

As described above, it is necessary to take measures against vibration during engine idling without changing the basic structure of the bumper and the body. Large bumper is used as a dynamic damper. In this case, the spring constant of the mounting part of the bumper as a dynamic damper is optimized for idling vibration, durable, simple structure, and the bumper falls off during normal driving You need to be careful not to fear.

In view of the above, according to the present invention, by attaching a bumper to a vehicle body via a rubber bush, a spring constant of a mounting portion as a dynamic damper is optimized for idling vibration, and a durable and simple structure is provided. An object of the present invention is to provide a structure that prevents the bumper from falling off during normal running.

[0009]

In order to solve the above-mentioned problems, the present invention has a structure in which a bumper is mounted on a vehicle body or a chassis. The bumper is mounted via a bush, and the bush is firmly attached to the inner surface of a cylindrical rubber. An inner sleeve made of a material having high rigidity and high tensile strength is provided, and an outer sleeve made of a material having high rigidity and high tensile strength is firmly bonded to the outer surface of the cylindrical rubber. Is set to be larger than the length of the outer sleeve, the outer sleeve is fixed so as not to cause relative displacement with the vehicle body or the chassis when the vehicle is used, and the bumper and the inner sleeve are fastened with a fastener penetrating the inner sleeve. A dynamic damper structure is characterized in that the bumper is used as a mass and the cylindrical rubber is used as a spring.

[0010]

FIG. 1 shows the relationship between a bumper and a vehicle body viewed from the front of a vehicle according to an embodiment of the present invention. FIG.
Shows the relationship between the bumper and the vehicle body as viewed from the side of the vehicle. The bumper 2 is usually provided with a bumper reinforcing portion 2a on the inner side, and is fastened to a chassis bracket 5 attached to the chassis 4 by a bolt via the bumper bracket 3. An engine 6 is mounted on the chassis 4 via an engine mount 7. The vibration caused by the explosion and rotation generated inside the engine is chassis 4
Is transmitted to the bumper 2 or the body 9 via the.

FIG. 8 is a three-dimensional perspective view of the bumper bracket 3. The bumper reinforcement 2 a is fastened to the bracket 3 via the bush 1. 3a is a hole for attaching to a chassis bracket. FIG. 9 shows a perspective view of the three-dimensional appearance of the bush 1. 1f is a through hole for a bumper mounting bolt.
FIG. 3 is a sectional view taken along the line BB of the portion A in FIG. A bumper reinforcing portion 2 a provided on the bumper 2 is fastened to the bracket 3 with a bolt 1 e via a bush 1. The bush 1 is formed in a cylindrical shape having a structure in which a rubber 1b is sandwiched between an outer sleeve 1a and an inner sleeve 1c. Inner sleeve 1c and outer sleeve 1
a is made of a material having high rigidity and high tensile strength, such as steel or ABS resin. Since the inner sleeve 1c is longer than the outer sleeve 1a, the inner sleeve 1c is firmly clamped between the bumper bracket 3 and the washer 1d by the bolt 1e. The outer sleeve 1a is firmly fixed to the bumper bracket 3 by press fitting or caulking. An upper gap 1g is secured between the bumper bracket 3 and the bumper reinforcement 2a, and a lower gap 1h is secured between the bumper bracket 3 and the washer 1d. FIG. 4 is a sectional view taken along line D-D of the portion C in FIG. The bumper bracket 3 is fastened to the chassis bracket 5.

FIGS. 5 to 7 show the behavior of the bush 1 as a spring when the bumper 2 operates as a dynamic damper. In FIG. 5, the bumper reinforcing portion 2a, that is, the bumper 2 is displaced upward by elastically deforming the rubber 1b due to engine idling vibration or the like. The upward displacement is limited by the lower gap 1h. In FIG. 6, the bumper reinforcing portion 2a, that is, the bumper 2 is displaced downward by elastically deforming the rubber 1b due to engine idling vibration or the like. The amount of downward displacement is limited by the upper gap 1g. In FIG. 7, the bumper reinforcing portion 2a, that is, the bumper 2 is displaced obliquely by elastically deforming the rubber 1b by engine idling vibration or the like. The amount of oblique displacement is limited by the gap 1g or 1h. Due to these displacement restrictions, the bumper 2 does not come off even if a large inertia force is applied during normal running or the like, and the rubber 1b is damaged.

FIG. 11 shows a simple schematic vibration system in which the bumper 2 is used as a dynamic damper.
Since the rubber 1b of the bush 1 functions as a spring on the body 9, the bumper 2 and the rubber 2a function as a dynamic damper. The vibration amount as the output of the vibration system with respect to the engine idling vibration input f is reduced to G2 by the dynamic damper effect. Conventional bumper 2
The vibration output when the body and the body 9 are directly connected is shown in FIG. 12 and FIG.
FIG. 3 shows a simple schematic diagram G1 as in FIG.
FIG. 10 shows a comparison between the vibration amount G1 for engine idling and the vibration amount G2 due to the dynamic damper effect according to the present invention in the prior art based on calculation results and experimental results. G1 for primary frequency f1 of idling rotary explosion
And G2, a remarkable reduction effect G3 is observed.

[0114]

1) By mounting the bumper on the vehicle body via the rubber bush, the spring constant of the mounting portion as the dynamic damper can be easily optimized with respect to idling vibration. Can be optimized. 2) Since the displacement of the rubber bush is limited, fatigue deterioration of the rubber is slowed down, and a stable spring constant is obtained. 3) Since a simple structure bush is used, there is no need to basically change a bumper and a related mounting mechanism, so that manufacturing costs are not sacrificed. 4) Since the bumper and the chassis or the body are connected by the through bolts, there is no possibility that the bumper will fall off even if the rubber as a spring is broken during normal running.

[Brief description of the drawings]

FIG. 1 is a front view of a front bumper mounting according to an embodiment of the present invention.

FIG. 2 is a side view of a front bumper attachment according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along a line BB of a portion A in FIG. 1;

FIG. 4 is a sectional view taken along line D-D of a portion C in FIG. 2;

FIG. 5 is a sectional view of a bush operation state.

FIG. 6 is a sectional view of a bush operation state.

FIG. 7 is a sectional view of a bush operation state.

FIG. 8 is a three-dimensional perspective view of a bumper bracket.

FIG. 9 is a perspective view of a three-dimensional external appearance of a bush of a portion E in FIG. 8;

FIG. 10 is a dynamic damper effect comparison diagram.

FIG. 11 is a schematic diagram of a floor vibration with a dynamic damper.

FIG. 12 is a schematic diagram of a floor vibration at the time of idling according to the related art.

FIG. 13 is a schematic diagram of a floor vibration at the time of idling according to the related art.

FIG. 14 is a sectional view taken along the line GG of an F portion of FIG. 15 showing a bumper attachment portion according to the related art.

FIG. 15 is a perspective view of a three-dimensional appearance of a bumper attachment part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bush 1a Outer sleeve 1b Rubber 1c Inner sleeve 1d Washer 1e Bumper mounting bolt 1f Bolt through hole 1g Upper gap 1h Lower gap 2 Bumper 2a Bumper reinforcement part 2b Bumper fastening part 3 Bumper bracket 4 Chassis 5 Frame bracket 6 Engine 7 Engine mount 8 Tire 9 Body 9a Body spring effect

Claims (1)

[Claims] 1. A structure for mounting a bumper to a vehicle body or a chassis, wherein the bumper is mounted via a bush, and the bush includes an inner sleeve made of a material having high rigidity and high tensile strength, which is firmly bonded to an inner surface of a cylindrical rubber. An outer sleeve made of a material having high rigidity and high tensile strength that is firmly bonded to the outer surface of the cylindrical rubber, the length of the inner sleeve is set to be larger than the length of the outer sleeve, The outer sleeve is fixed so as not to cause relative displacement with the vehicle body or the chassis when the vehicle is used, the bumper and the inner sleeve are fastened with a fastener penetrating the inner sleeve, the bumper is used as a mass, and the cylindrical rubber is used as a spring. A dynamic damper structure characterized by: