Vehicle body parts and method for improving vibration and noise performance of vehicle body parts

Abstract

To provide a method of improving vibration and noise performance of a vehicle body component efficiently under limited conditions.SOLUTION: A vehicle body component 1000 includes: an input part 100i into which input vibration is input; a concentrated part in which traveling wave components of vibration propagated from the input part 100i are concentrated; and a damping material provided in the concentrated part and damping vibration propagated to the concentrated part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle body part and a method for improving the vibration and noise performance of a vehicle body part. [Background technology]

[0002] 2. Description of the Related Art In an automobile, noise and vibrations generated by input from the road surface while driving and by the driving of the powertrain such as the engine may be transmitted into the passenger compartment through the vehicle body, particularly through the frame parts. In order to prevent this noise and vibration from being perceived by passengers in the vehicle, studies are being conducted to reduce the noise and vibration. For example, a method has been disclosed in which a model of a vibration transmitting part is identified based on the distribution of kinetic energy and strain energy, and optimization is attempted (Patent Document 1). Also, a method has been disclosed for reducing vibration and noise of automobile parts by calculating an optimal bead shape using modal analysis and equivalent radiation power (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6769536 [Patent Document 2] Patent No. 6798595 Summary of the Invention [Problem to be solved by the invention]

[0004] These inventions have had structural issues, such as the inability to effectively damp vibrations using only a steel plate structure. Furthermore, distribution analysis based on vibration energy only captures the strength of vibrations, and is unable to determine the direction of vibrations. Furthermore, there are many small modes in the mid- to high-frequency range, resulting in a patchy distribution of vibrations, making it difficult to fully understand the vibrations. Furthermore, in recent years, in addition to quietness, automobiles are required to be lightweight in order to improve collision safety performance and fuel economy, and measures to improve quietness are therefore limited.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for efficiently improving the vibration and noise performance of vehicle body parts under limited conditions. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following means. The vehicle body part according to the present invention comprises an input portion to which input vibration is input, a concentration portion to which traveling wave components of vibration propagating from the input portion are concentrated, and a damping material provided in the concentration portion to damp the vibration propagated to the concentration portion.

[0007] According to this invention, a concentrating portion is provided where the traveling wave component of vibration propagating from an input portion is concentrated. As a result, when, for example, input from the road surface or vibration from the powertrain propagates to the body part, the vibration is concentrated at the concentrating portion, thereby preventing the vibration from propagating to other parts. Furthermore, the concentrating portion is provided according to the shape of the body part. In other words, the concentrating portion can be provided without affecting the vehicle layout. This makes it possible to efficiently improve the noise and vibration performance of the body part under limited conditions.

[0008] Furthermore, the vehicle body part is provided with a damping material that attenuates vibrations propagated to the concentrated area. This allows for more efficient suppression of vibrations propagated to the vehicle body part. Furthermore, compared to providing damping material to the entire vehicle body part, this method can provide optimal results without affecting the vehicle layout. In addition, the amount of damping material can be reduced, which contributes to reducing the vehicle's weight and cost.

[0009] Furthermore, the method for improving the vibration and noise performance of a vehicle body part according to the present invention includes an analysis step of analyzing the traveling wave components of vibrations propagating to the vehicle body part, and a shape countermeasure step of changing the shape of the vehicle body part based on the results of the analysis step, and providing a concentration portion in the vehicle body part where the traveling wave components are concentrated.

[0010] According to this invention, the method comprises an analysis step of analyzing the traveling wave components of the vibrations propagating to the vehicle body part, and a shape countermeasure step of changing the shape of the vehicle body part based on the results of the analysis step and providing a concentration part in the vehicle body part where the traveling wave components are concentrated. By providing one or more locations where vibrations input to a vehicle body component are concentrated and propagated, it is possible to prevent the entire vehicle body from vibrating, thereby preventing a deterioration in the vehicle's noise and vibration performance. Furthermore, by taking measures only in the shape of the vehicle body component, it is possible to improve the vehicle's noise and vibration performance without affecting the vehicle layout or vehicle weight, compared to measures that involve adding separate sound-insulating materials, etc.

[0011] The present invention may also include a damping step of providing a damping material at the concentrated portion provided by the shape improvement step.

[0012] According to this invention, a damping step of providing a damping material in the concentrated portion is provided. This allows further improvement in vibration and noise performance by providing the damping material only in the concentrated portion of the vehicle body part. In other words, vibration and noise performance can be improved without providing the damping material in the entire vehicle body part. Therefore, compared to providing the damping material in the entire vehicle body part, the amount of damping material can be reduced, which contributes to weight reduction and cost reduction of the vehicle.

[0013] The method may also include a vibration and acoustic analysis step of analyzing sounds generated by vibrations propagating to the vehicle body parts.

[0014] According to this invention, a vibro-acoustic analysis step is provided for analyzing the sound generated by vibrations propagating to the vehicle body parts. By analyzing the vibrations propagating to the vehicle body parts as sounds perceived by vehicle occupants, the effects of the shape improvement step and the damping step can be confirmed. This can more reliably contribute to improving the vibration and noise performance. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a method for efficiently improving the vibration and noise performance of a vehicle body part under limited conditions. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view of a vehicle body part according to an embodiment of the present invention; [Figure 2] This is a flat plate model of the body part shown in Figure 1. [Figure 3] 3 is a diagram showing an analysis process of the flat plate model shown in FIG. 2. [Figure 4] 10 is a schematic diagram showing a state in which a backing plate and a damping material are attached to a transmission portion of a vehicle body part. FIG. [Figure 5] FIG. 5 is a side view of FIG. [Figure 6] This is a modified example in which the backing plate shown in FIG. 4 is made uneven and damping materials are provided at intervals. [Figure 7] FIG. 7 is a side view of FIG. [Figure 8] FIG. 1 is a first diagram showing the results of analysis according to the present embodiment. [Figure 9] FIG. 2 is a second diagram showing the results of the analysis of this embodiment. [Figure 10] FIG. 3 is a third diagram showing the results of the analysis of this embodiment. [Figure 11] This is the result of applying the analysis of this embodiment to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a vehicle body part 1000 and a method for improving vibration and noise performance of the vehicle body part 1000 according to one embodiment of the present invention will be described with reference to the drawings. 1 is a body frame part around the engine room of an automobile. In this embodiment, the body part 1000 includes a side member 100, a wheel housing 200, and a dash panel 300. The side members 100 are provided in pairs on the left and right sides of the vehicle body. The side members 100 are hat-shaped cross-section members arranged in the engine compartment along the vehicle longitudinal direction. By making the side members 100 have a hat-shaped cross-section, the strength of the side members 100 against inputs in the vehicle longitudinal direction is ensured, and the occupant protection performance is ensured, for example, in the event of a frontal collision of the vehicle. At the vehicle front ends of the pair of side members 100 provided as described above, a front member and a bumper (not shown) are provided across the vehicle transverse direction to connect the left and right side members 100 to each other. As shown in FIG. 1, at the rear of the side member 100, a tire housing 200 is attached to the side surface on the outer side of the vehicle, and a dash panel 300 is attached to the rear end of the vehicle.

[0018] The tire housing 200 is a member that forms a space for accommodating a tire. The tire housing 200 also includes a damper base 200D for attaching a suspension, to which a tire is attached, to the vehicle body part 1000. As shown in FIG. 1 , the lower part of the tire housing 200 is attached to the side member 100, and the upper part of the tire housing 200 is attached to the dash panel 300. Dash panel 300 is a wall-like member that separates the engine compartment from the cabin of an automobile. Dash panel 300 has a plurality of through-holes for accommodating components (e.g., a steering shaft, air conditioning piping, etc.) that extend from the engine compartment to the cabin. These through-holes are sealed with appropriate sealing materials depending on the waterproofing performance, airtightness, etc. In the vehicle body part 1000, when the side member 100, the wheel housing 200, and the dash panel 300 are attached, spot welding is preferably used.

[0019] Each component part of the above-described vehicle body part 1000 is formed by press-forming a steel plate having a thickness of mainly 0.6 mm to 2.0 mm. These vehicle body components 1000 are components that form the engine compartment of an automobile. In particular, engine mounts are provided on the side members 100. Therefore, these parts are susceptible to the influence of vibration inputs that occur in the engine and gears when the engine is running.

[0020] The following is an example of vibration propagation in the vehicle body part 1000 according to this embodiment: Vibration from a portion of the side member 100 on the front side of the vehicle propagates through the side member 100 to the rear side of the vehicle and is transmitted to the dash panel 300. In the following, this transmission will be described as a transmission system 1000V as shown in Fig. 1. Transmission system 1000V includes an input portion 100i on the vehicle front side of side member 100, which is a point where external input vibration is input, a transmission portion 100t on the vehicle rear side of side member 100, which is an intermediate portion between input portion 100i and dash panel 300, and dash panel 300, which is an output portion to which the vibration is transmitted.

[0021] The vibrations propagated by this 1000V transmission system are further propagated to the cabin side, for example, to a floor panel or pillar parts (not shown), via dash panel 300 (output part). If the vibrations propagate to areas where vehicle occupants are likely to perceive the vibrations as sound (for example, pillar parts around the ears), it can cause discomfort to the occupants.

[0022] In response to the above-mentioned problem, in this embodiment, the traveling wave component of the vibration propagating to the body part 1000 is analyzed (analysis step), and based on the results, the shape of the body part 1000 is changed, and a concentrated portion 100C where the traveling wave component is concentrated in the body part 1000 is intentionally provided (shape countermeasure step).

[0023] In this embodiment, the term "concentrated traveling wave components" refers to a state in which the directions of the traveling wave components of adjacent meshes are aligned within 15° of each other at frequencies (when power is being transmitted) that are 10 times higher than the power magnitude of meshes (described later) in the transmission system 1000V compared to the power magnitude at low frequencies (when little power is being transmitted). Hereinafter, such a region where the traveling wave components are aligned within 15° may be referred to as a concentrated portion 100C. As an example of an analysis, the power at a specific mesh is 1.45e-4mW at a certain frequency where it is not transmitted, while the power at a certain frequency where it is transmitted is 1.97mW, and the difference in orientation between adjacent meshes is 0.5 to 1.2°. These figures vary greatly depending on the unit system, analysis conditions, etc.

[0024] The specific steps of the countermeasure according to this embodiment are as follows. The above analysis is performed using a simplified model of the transmission system 1000V shown in FIG. 1 as a flat plate, as shown in FIG. 2, in which the input unit 100i having the input point 100ip, the transmission unit 100t, and the dash panel 300 are treated as a single flat plate, and the other peripheral parts are treated as an end portion 100e. In the analysis using this model, the vibration is analyzed for each mesh obtained by dividing the flat plate into fixed dimensions. The division is performed, for example, by dividing the plate into squares of 5 mm or 10 mm, and each divided area is called a mesh. On the flat plate, the input unit 100i, the transmission unit 100t, and the dash panel 300 are arranged in this order from the direction corresponding to the front side of the vehicle to the direction corresponding to the rear side. In addition, in the flat plate model of the transmission system 1000V shown in Fig. 2, the end 100e is assumed to be fixed and immovable during analysis.

[0025] <Analysis steps> The analysis according to this embodiment is performed assuming a case in which vibration is applied to the input point 100ip shown in Fig. 2 in the direction perpendicular to the plate. The results of the following analysis method can be confirmed, for example, by an experimental technique such as a four-point method (two points in the X direction, two points in the Y direction) power flow measurement (Japan Automobile Research Institute, vibration intensity measurement theory). That is, the end of the plate corresponding to the transmission system in Fig. 2 is fixed at end 100e, and vibration is applied from the part corresponding to input point 100ip.

[0026] Specifically, in a side view of the input section of Figure 2 shown in Figure 3, when vibration is added as input I to input point 100ip in a transmission system of 1000V, the ERP (Equivalent Radiated Power) at the output section and the power flow in transmission section 100t are calculated by computer. It should be noted that the vibrations input to the input unit 100i as the subject of this analysis are assumed to be medium to high frequencies of 500 Hz or more, which have a relatively large number of modes.

[0027] The results calculated based on the above analysis are shown in Figure 8. Figure 8 shows the analysis results for the flat plate-shaped transmission part 100t shown in Figure 2. In this analysis, the vibration is decomposed into standing wave components and traveling wave components. In Figure 8, the traveling wave components are represented by arrows. Specifically, the length of the arrow indicates the magnitude of the traveling wave for each mesh. When a similar analysis is performed on the transmission system 1000V as the body part 1000 shown in Figure 1, the results shown in Figure 11 are obtained.

[0028] 8 and 9, the arrows indicate that a particularly large traveling wave component is occurring at the position where the arrow is located. The magnitude of the traveling wave component is proportional to the size of the arrow shown in FIGS. 8 and 9. The direction of the arrow indicates the direction of the traveling wave (vibration). In this embodiment, the magnitude of the traveling wave component is expressed by the size of the arrow as described above, but this is not limited to this. For example, the drawings may be colored and expressed by the intensity or brightness of the color. Figure 8 shows the results for the 1597 Hz frequency band. As shown in Figure 8, the vibration transmission direction is not uniform in the 1000 V transmission system before the countermeasures were taken. When the concentrating section 100C is not present, there are many frequency bands in which the vibration transmission direction is not uniform. Alternatively, the vibration transmission direction is not uniform in particularly required frequency bands.

[0029] To address this issue, the following shape countermeasure step is carried out. By providing the concentrating portion 100C in this step, the propagation of vibration to areas other than the concentrating portion is suppressed and the direction of vibration propagation is made uniform. This allows the direction of vibration propagation to be uniform across many frequency bands, or by targeting particularly required frequency bands and aligning the direction of vibration propagation, we will consider further suppressing the effects of vibration propagation.

[0030] <Shape measures step> Based on the results of the above analysis step, measures to suppress vibrations are taken, such as by changing the shape of the vehicle body. For example, there are methods for changing the shape of the part related to the vibration output part, or for providing damping to the part related to the output part. There are also methods for changing the shape of the part related to the input part 100i, or for providing damping to the part related to the input part 100i. Alternatively, the damping may be provided only in the concentrated part, or may be provided in other parts.

[0031] 4 and 5, measures to suppress the propagation of vibration transmitted to dash panel 300 include, for example, changing the shape of dash panel 300. Alternatively, a method of adding a damping material 100d and a backing plate 100a to transmission portion 100t is preferably used. That is, in this embodiment, changing the shape of the body part 1000 includes changing the existing shape of the body part 1000 itself without adding a new part to the body part 1000. In addition, it also includes adding a new part to the body part 1000 and changing the shape of the entire body part without changing the existing shape of the body part 1000.

[0032] A viscoelastic material, for example, is preferably used for the damping material 100d. By attaching the damping material 100d to the transmission part 100t, it damps vibrations propagated to the transmission part 100t. The damping material 100d is preferably provided so as to be sandwiched between the transmission part 100t and the backing plate 100a. The transmission part 100t and the damping material 100d, or the damping material 100d and the backing plate 100a, are preferably fixed by, for example, adhesive. Alternatively, the damping material 100d may be fixed by sandwiching the damping material 100d between the transmission part 100t and the backing plate 100a and then fixing the transmission part 100t and the backing plate 100a by welding or the like.

[0033] A steel plate is preferably used for the backing plate 100a. The backing plate 100a reinforces the transmission part 100t, making it less susceptible to vibration, thereby suppressing vibration in the transmission part 100t. The backing plate 100a is preferably attached so as to cover the damping material 100d attached to the transmission part 100t. Furthermore, spot welding, for example, is preferably used to fix the backing plate 100a and the transmission part 100t. The backing plate 100a does not have to be attached. In this case, it is preferable that the damping material 100d is attached to the transmission part 100t by adhesive.

[0034] 6 and 7, the backing plate 100a may be made uneven. In this case, the damping material 100d may be provided only where the backing plate 100a is close to the transmission part 100t. This more effectively suppresses the propagation of vibration. Furthermore, the transmission of vibrations may be suppressed by providing a plurality of beading processes (not shown) on the surface of the transmission part 100t. Furthermore, all of these measures may be applied simultaneously.

[0035] As a result of examining vibration suppression through the shape countermeasure step described above, Fig. 9 shows the calculation results when a flat backing plate 100a and damping material 100d are attached to the transmission part 100t as shown in Fig. 4 and Fig. 5. Fig. 10 shows the calculation results when damping material 100d is provided at intervals on the transmission part 100t and an uneven backing plate 100a is attached.

[0036] The results shown in FIG. 9 do not show much change compared to FIG. 8, which indicates that the effect of the measures shown in FIG. 9 is relatively small. In contrast, the results shown in FIG. 10 indicate that the direction of vibration propagation is uniform. Furthermore, it can be seen that the areas where the arrows in FIG. 10 are relatively long (large amplitude) are concentrated in one location. In other words, it can be seen in FIG. 10 that concentrated area 100C was provided by the shape countermeasure step. In this way, by using a computer to calculate the effect of shape on vehicle body vibration, it is possible to consider the optimal shape without actually molding parts or conducting experiments in a laboratory.

[0037] In this way, it was confirmed that in a 1000V transmission system, by aligning the direction of vibration propagation and providing a concentration section 100C where the traveling wave component of the vibration is concentrated, it is possible to suppress vibration propagation in other parts. Furthermore, by providing the damping material 100d in the concentrated portion 100C formed in this manner, vibration countermeasures may be implemented using the minimum amount of damping material 100d required.

[0038] As described above, the vehicle body component 1000 according to this embodiment includes the concentrating portion 100C where the traveling wave component of the vibration propagating from the input portion 100i is concentrated. As a result, when, for example, an input from the road surface or vibration of the powertrain propagates to the vehicle body component 1000, the vibration is concentrated and propagated to the concentrating portion 100C, thereby preventing the vibration from propagating to other parts. Furthermore, the concentrating portion 100C is provided according to the shape of the vehicle body component 1000. In other words, the concentrating portion 100C can be provided without affecting the vehicle layout. This allows the vibration and noise performance of the vehicle body component 1000 to be efficiently improved under limited conditions.

[0039] Furthermore, the vehicle body component 1000 is provided with a damping material 100d that damps vibrations propagated to the concentrated portion 100C. This allows for more efficient suppression of vibrations propagated to the vehicle body component 1000. Furthermore, compared to providing the damping material 100d over the entire vehicle body component, this provides optimal effects without affecting the vehicle layout. In addition, the amount of damping material 100d can be reduced, which contributes to reducing the weight and cost of the vehicle.

[0040] It also includes an analysis step of analyzing the traveling wave component of the vibration propagating to the body part 1000, and a shape countermeasure step of changing the shape of the body part 1000 based on the results of the analysis step and providing a concentration part 100C where the traveling wave component in the body part 1000 is concentrated. By providing one or more locations where vibrations input to the vehicle body component 1000 are concentrated and propagated, it is possible to prevent the entire vehicle body from vibrating, thereby preventing a deterioration in the vibration and noise performance of the vehicle body. Furthermore, by taking measures only in accordance with the shape of the vehicle body component 1000, it is possible to improve the vibration and noise performance without affecting the vehicle layout and vehicle weight, compared to a method of adding a separate sound-insulating material.

[0041] The method also includes a damping step of providing the damping material 100d in the concentrated portion 100C. This allows the vibration noise performance to be further improved by providing the damping material 100d only in the concentrated portion 100C of the vehicle body component 1000. In other words, the vibration noise performance can be improved without providing the damping material 100d over the entire vehicle body component. Therefore, compared to when the damping material 100d is provided over the entire vehicle body component, the amount of the damping material 100d can be reduced, which contributes to reducing the weight and cost of the vehicle.

[0042] The method also includes a vibration-acoustic analysis step for analyzing the sound generated by the vibration propagating to the vehicle body part 1000. By analyzing the vibration propagating to the vehicle body part 1000 as the sound perceived by the vehicle occupants, it is possible to confirm the effects of the shape measure step and the damping step. This can more reliably contribute to the improvement of vibration and noise performance.

[0043] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the vibration countermeasure according to this embodiment may be applied not only to the above-mentioned parts of the vehicle, but also to other parts such as floor panels of the vehicle.

[0044] In addition, within the scope of the spirit of the present invention, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Explanation of symbols]

[0045] 100C concentrated section 100d damping material 100i input section 1000 body parts

Claims

1. an input unit to which input vibration is input; an output section to which vibration is transmitted; a transmission section that is an intermediate section between the input section and the output section, a backing plate having a concave-convex shape and having a damping material on the convex portions is attached to the transmission part via the damping material; a concentration portion where the traveling wave component of the vibration propagating from the input portion is concentrated, A vehicle body part provided on the transmission part.

2. an analysis step of analyzing a traveling wave component of vibration propagating to a vehicle body part; a shape countermeasure step of modifying the shape of the vehicle body part based on the result of the analysis step, and providing a concentrated portion in the vehicle body part where the traveling wave components are concentrated; Equipped with Methods for improving the noise and vibration performance of vehicle body parts.

3. a damping step of providing a damping material at the concentrated portion provided by the shape control step; The method for improving vibration and noise performance of a vehicle body part according to claim 2.

4. a vibration-acoustic analysis step of analyzing a sound generated by vibration propagating to the vehicle body part; The method for improving vibration and noise performance of a vehicle body part according to claim 2 or 3.

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