WO2019069365A1 - Vibration control structure of vehicle body, and vibration control method for vehicle body - Google Patents

Abstract

In the present invention, a viscoelastic body is directly adhered to at least a part of the surface of a frame member of a vehicle body.

Description

Vibration control structure of vehicle body and vibration control method

The present invention relates to a damping structure and a damping method of a vehicle body.

The resonance of the vehicle body greatly affects the ride quality of the vehicle. As a method of suppressing the occurrence of resonance, the natural frequency of the vehicle body is shifted from the frequency of the input vibration by increasing the rigidity of the vehicle body, but this method causes an increase in the weight of the vehicle body. On the other hand, there is also a method of suppressing deformation at the time of vibration of the vehicle body by providing a hydraulic shock absorber in a reinforcement device of the vehicle body. Patent Document 1 discloses a technique related to the latter.

JP 2008-2594 A

However, the above-described hydraulic shock absorber-equipped reinforcing device needs to be installed across the space defined by the structural members of the vehicle body, which has been a factor in reducing the space utilization rate of the vehicle.

An object of the present invention is to improve the ride comfort of a vehicle by suppressing the deformation at the time of vibration of the vehicle body while improving the space utilization rate of the vehicle.

In one aspect of the present invention, the visco-elastic body is directly bonded to at least a part of the surface of the frame member of the vehicle body.

According to the above aspect, it is possible to improve the ride comfort of the vehicle by suppressing the deformation at the time of the vibration of the vehicle body while improving the space utilization rate of the vehicle.

FIG. 1A shows a model of forced oscillation with damping in one degree of freedom. FIG. 1B shows the characteristics of inertance versus frequency for the model of FIG. 1A. FIG. 1C shows an example of the vibration waveform of the model of FIG. 1A. FIG. 2A shows a state of the vehicle body vibrating in the skeletal natural vibration mode before deformation. FIG. 2B shows a variant when the vehicle body of FIG. 2A vibrates in certain skeletal natural vibration modes. FIG. 2C shows a variant when the vehicle body of FIG. 2A vibrates in another skeletal natural vibration mode. FIG. 3 shows an example of a framework member extending in the vehicle width direction. FIG. 4A shows an example of the deformation distribution of the vehicle body in some representative skeletal natural vibration modes. FIG. 4B shows the arrangement of displacement measurement points of the vehicle body model according to FIG. 4A. FIG. 5A is a perspective view of a front portion of a vehicle body of the vehicle according to the embodiment. FIG. 5B is a front view of the front of the vehicle body of the vehicle according to the embodiment. FIG. 5C is a cross-sectional view taken along the line VC-VC of FIG. 5B. FIG. 6A is a perspective view of the rear portion of the vehicle body according to the embodiment. FIG. 6B is a front view of the rear portion of the vehicle body according to the embodiment. FIG. 6C is a cross-sectional view taken along the line VIC-VIC of FIG. 6B. FIG. 7 is a cross-sectional view of a vibration damping sheet according to an embodiment. FIG. 8 is a graph schematically showing the sound pressure measurement results when the vehicle according to the example passes over the protrusion.

As a damping material advantageous in terms of space utilization of the vehicle, there is a visco-elastic body such as a damping sheet. Since the visco-elastic body exhibits a vibration damping effect by converting the input vibrational energy into thermal energy, the surface of a member which easily transmits the vibration to the visco-elastic body, that is, a floor panel or the like is usually relatively It is used by being laminated on the surface of a member having low bending rigidity.

Contrary to such conventional technical common knowledge, the inventors of the present invention carried out a running test by bonding a visco-elastic body to the surface of a skeletal member. It has been surprisingly found that the direct attachment of the visco-elastic body to the surface of the frame member suppresses deformation during vibration of the vehicle body and greatly improves the ride quality of the vehicle. This is the vibrational damping obtained when the damping coefficient c which was originally small (approximately zero) is increased in the forced vibration model with damping (see FIG. 1A) represented by the equation of motion of equation (1) It is considered that the same effect as the effect was obtained.

Here, x is displacement, m is mass, c is a damping coefficient, k is a spring constant, F is an amplitude of excitation force, ω is an angular frequency, X is an amplitude of displacement, and α is an initial phase.

That is, the peak value (see FIG. 1B) of the inertance (also referred to as acceleration) defined by the equation (2), which is given by the equation (3), converges rapidly due to the increase of the damping coefficient c. It is considered that the amplitude A (see FIG. 1C) of is reduced.

Moreover, according to the above-described vibration damping structure, the viscoelastic body does not cross the space defined by the constituent members of the vehicle body, and the space utilization rate of the vehicle is improved. Further, since the visco-elastic body is adhered to the surface of the skeletal member, it is not necessary to largely change the layout of the periphery or to newly install a mounting bracket. Furthermore, even if a visco-elastic body is provided in the frame member located in the crushable zone or crample zone of the vehicle body, the rigidity of the visco-elastic body is negligibly small, so that the crush deformation of the vehicle body at the time of collision is not inhibited.

The visco-elastic body is not particularly limited as long as the visco-elastic body is in close contact with the surface of the framework member and can convert vibrational energy into other energy such as thermal energy, and is used for a known damping sheet, asphalt system, butyl rubber Viscoelastic bodies, such as a system and a resin system, are employable. Examples of known vibration damping sheets include Sandine manufactured by Parker Asahi Co., Ltd., Zetro beta manufactured by Ida Sangyo Co., Ltd., Zetro gamma manufactured, and the like.

The vehicle body is composed of a framework member which forms a framework of the vehicle body, and a panel material supported by the framework member. One skeletal member is coupled to the other skeletal member through the coupling portion. The frame members include front bumper reinforcement, radiator core support, cowl top, steering member, waist rear, rear panel, front cross member, front side member, roof side rail, front roof rail, roof bow, rear roof rail, front pillar, center pillar , Rear pillars, side sills, front floor cross members, center floor cross members, rear floor cross members, floor side members, rear side members, rear cross members, rear bumper reinforcements, and the like.

There are innumerable natural vibration modes per car body. Among the natural vibration modes of the vehicle body, a mode in which the entire vehicle body frame vibrates in a relatively large manner is called "skeleton natural vibration mode". In general, there are several tens of skeletal natural vibration modes. 2B and 2C show an example of a skeletal natural vibration mode.

The inventors of the present invention observed the deformation mode of the skeletal natural vibration mode, and examined which skeletal member the visco-elastic body can be more reliably exhibited by adhering the viscoelastic body. Then, in many skeletal natural vibration modes, the amount of deformation of the skeletal member extending in the vehicle width direction tends to be larger than the amount of deformation of the skeletal member extending in the other direction (vehicle longitudinal direction or vehicle vertical direction). I found that. That is, it has been found that more vibration energy can be dissipated by bonding the visco-elastic body to the frame member extending in the vehicle width direction. The amount of deformation of the skeletal member is the amount of strain at a point (maximum strain point) at which the amount of strain on the surface of the skeletal member becomes maximum. Further, as a frame member extending in the vehicle width direction, the front bumper reinforcement 1, the support radial core upper 2, the cowl top 3, the steering member 4, the front roof rail 5, the roof bow 6, the rear roof rail are exemplified in FIG. 7 includes a waist rear 8, a rear panel 9, and a rear bumper reinforcement 10. Front floor cross members, center floor cross members, rear floor cross members, etc. are also frame members extending in the vehicle width direction.

Furthermore, the inventors of the present invention have found that in many skeletal natural vibration modes, the amount of deformation of the frame members disposed at the front end or the rear end of the vehicle, in particular the amount of deformation of the bumper reinforcement is the amount of deformation of the other frame members. I found that I tend to be bigger. That is, more vibrational energy is dissipated by bonding the visco-elastic body to the frame members disposed at the front end of the vehicle and / or the rear end of the vehicle, in particular, the front bumper reinforcement and / or the rear bumper reinforcement. I found that I could do it. An example of the above trend is shown in FIG. 4A. FIG. 4A shows a pair of points separated in the vehicle width direction (A1 and A2, B1 and B2, C1 and C2, D1 and D2, E1 and E2, F1 and F2, G1 in the vehicle model shown in FIG. 4B. And G2) indicate how much the spacing between them fluctuates in a typical skeletal natural vibration mode. The horizontal axis indicates the longitudinal position of the displacement measurement points A1 and A2 to G1 and G2 (see FIG. 4B) on the framework member, and the vertical axes indicate points forming a pair (for example, A1 and A2) Indicates the amount of change in distance between One broken line corresponds to one skeletal natural vibration mode. In the example of FIG. 4A, in many skeletal natural vibration modes, skeletal members (for example, rear panel and rear bumper reinforcement) arranged near displacement measurement points (G1, G2) at the rear end of the vehicle are in the vicinity of other displacement measurement points. There is a tendency to deform more than the skeletal member.

Next, the present inventors pay attention to whether the damping effect of the vibration can be more reliably exhibited if the visco-elastic body is adhered to the surface of any part of the framework member extending in the vehicle width direction. The deformation mode of the vibration mode was observed. Then, it has been found that in many skeletal natural vibration modes, the maximum strain point tends to occur at the center in the vehicle width direction of the framework member extending in the vehicle width direction. That is, it has been found that vibration energy can be dissipated more efficiently by adhering a visco-elastic body to the surface of the central portion in the vehicle width direction. The surface of the skeletal member includes the front and rear side surfaces, the left and right side surfaces, and the upper and lower surfaces of the skeletal member. In addition, when the skeletal member has a closed cross-sectional structure or an open cross-sectional structure, the surface includes not only the outer surface of the skeletal member but also the inner surface.

There are no particular limitations on the size and shape of the region to which the visco-elastic body is bonded (hereinafter referred to as a bonded region) on the surface of the skeletal member. The length of the adhesion region in the extending direction of the skeletal member is preferably 10% or more of the length of the skeletal member in order to obtain the vibration damping effect more reliably. More preferably, it is 30% or more, more preferably 50% or more, and still more preferably 70% or more. The width of the adhesion region in the direction orthogonal to the extending direction of the skeletal member is preferably 10% or more of the maximum width of the skeletal member in the same direction in order to obtain the vibration damping effect more reliably. More preferably, it is 30% or more, more preferably 50% or more, and still more preferably 70% or more.

Further, the visco-elastic body may be disposed intermittently on the surface of the skeletal member, or may be disposed continuously from the coupling portion on one end side of the skeletal member to the coupling portion on the other end side. In the latter case, the maximum strain point of the skeletal member can be covered with the visco-elastic body more reliably. The thickness of the visco-elastic body is not particularly limited, but is preferably 2 mm or more in order to obtain the vibration damping effect more reliably. More preferably, it is 4 mm or more, more preferably 6 mm or more, and still more preferably 8 mm or more.

Furthermore, a reinforcing sheet material may be provided in close contact with the surface of the viscoelastic body opposite to the surface bonded to the surface of the skeletal member (hereinafter referred to as the bonding surface). According to this configuration, the movement of the visco-elastic body in the vicinity of the surface opposite to the bonding surface is restrained by the reinforcing sheet material, so that the shear force is easily applied to the visco-elastic body. The vibration propagated to the elastic body is more efficiently converted to thermal energy. The reinforcing sheet material may be a metal foil such as aluminum foil or a cloth-like sheet such as glass cloth.

<Example>
The vehicle V according to the example in which the visco-elastic body was adhered to the surface of the frame member and the vehicle according to the comparative example in which the visco-elastic body was not adhered were prepared and subjected to the comparative traveling test. As shown in FIGS. 5A to 6C, the vehicle V has a damping sheet S bonded to the surfaces of the front bumper reinforcement 1 and the rear bumper reinforcement 10. As the vibration damping sheet S, Sandine manufactured by Parker Asahi Co., Ltd. was used. As shown in FIG. 7, this vibration damping sheet S includes an adhesive layer 21 made of butyl rubber which is a visco-elastic body, and an aluminum foil 22 which is a reinforcing sheet material provided in close contact with one surface of the adhesive layer 21. ing. The surface of the adhesive layer 21 opposite to the surface in close contact with the aluminum foil 22 is bonded to the surface of the front bumper reinforcement 1 or the rear bumper reinforcement 10 which is a frame member.

In the running test, the sound pressure at the position of the occupant's ear was measured when the projection was crossed at a predetermined vehicle speed. The measurement results are schematically shown in FIG. In FIG. 8, the solid line is a graph of the vehicle V according to the example, and the broken line is a graph of the vehicle according to the comparative example. As shown in FIG. 8, the sound pressure level of the example is lower than that of the comparative example.

In addition, a sensory evaluation test on ride comfort was also conducted. As a result, in each evaluation item, the example obtained an evaluation superior to the comparative example.

The above embodiments are merely exemplary described to facilitate the understanding of the invention. The technical scope of the invention is not limited to the specific technical matters disclosed in the above embodiment, but also includes various modifications, alterations, and alternative technologies that can be easily derived therefrom.

For example, in the above embodiment, the vehicle body of the sedan has been described as an example, but the configuration in which the visco-elastic body is directly adhered to the surface of the frame member of the vehicle body is a compact car, wagon, SUV, van, truck, bus, motorcycle, etc. Applicable to other types of car bodies. Further, the configuration of the above embodiment can be applied not only to the vehicle body of an internal combustion engine powered by an internal combustion engine but also to the vehicle body of an electric vehicle such as an electric vehicle, a hybrid vehicle and a fuel cell vehicle powered by an electric motor.

The damping structure and the damping method of a vehicle body according to the present invention can be used for damping a vehicle body of a vehicle such as an automobile.

21 Adhesive layer (viscoelastic body)
22 Aluminum foil (reinforcement sheet material)
1 Front bumper reinforcement 10 Rear bumper reinforcement

Claims (7)

1. A damping structure of a vehicle body, wherein a visco-elastic body is directly bonded to at least a part of a surface of a framework member.
2. The vehicle body damping structure according to claim 1, wherein the frame member is a frame member extending in a vehicle width direction.
3. The vehicle body damping structure according to claim 2, wherein the framework member is a framework member disposed at a front end or a rear end of the vehicle body.
4. The vehicle body damping structure according to claim 3, wherein the frame member is at least one of a front bumper reinforcement and a rear bumper reinforcement.
5. The vehicle body damping structure according to any one of claims 2 to 4, wherein the visco-elastic body is adhered to a surface of a central portion in a vehicle width direction of the frame member.
6. The reinforcing sheet material according to any one of claims 1 to 5, wherein a reinforcing sheet material is provided in close contact with the surface of the visco-elastic body opposite to the surface bonded to the surface of the frame member. Vibration control structure of the car body.
7. A damping method of a vehicle body, wherein a visco-elastic body is directly bonded to at least a part of a surface of a framework member.

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