JP6311767B1 - Sound insulation structure on the vehicle floor - Google Patents

Abstract

In consideration of the difference in particle velocity in the plane of a floor panel, the surface density of a sound absorbing material is set more appropriately so that both sound insulation and weight reduction can be satisfied. A sound absorbing material 17 is disposed in a space K between a floor panel 1 on the incident side of road noise as noise and a floor carpet 16 disposed above the floor panel. Of the floor panel 1, a floor region F1 (for example, a rear seat installation region) surrounded by strength members is divided into a square panel region P1 and another region P2 by, for example, a bead portion 18 constituting a vibration node. Is done. The sound absorbing material 17 in the panel region P1 has a high density region M1 and a low density region M2 in plan view (in the plane of the panel region). [Selection] Figure 9

Description

  The present invention relates to a sound insulation structure for a vehicle floor.

  As a panel structure for sound insulation, an inner panel is disposed at a distance from an outer panel on which noise is incident, and a space between the outer panel and the inner panel is filled with a sound absorbing material 2 A heavy wall structure is known.

  In a vehicle, road noise is transmitted to the vehicle interior via the floor panel, so that sound insulation at the floor panel portion is important. Patent Document 1 discloses a floor panel panel portion having a double wall structure.

JP 2014-189230 A

  By the way, in the double wall structure adopted for sound insulation, the larger the surface density of the sound absorbing material (that is, the greater the air flow resistance in the space), the more preferable for improving sound insulation, As the surface density increases, the weight increases, which is not preferable in terms of weight reduction.

  In the conventional double wall structure, the surface density of the sound absorbing material is set to be the same in the plane of the outer panel (along the surface of the outer panel). That is, conventionally, in the space between the outer panel and the inner panel, air (particles) is considered to move almost straight (in a direction perpendicular to the outer panel) from the outer panel toward the inner panel. In fact, the fact that the material of the sound absorbing material is changed in the plane of the outer panel is not considered at all.

  On the other hand, when a double wall structure is adopted for the floor panel portion of the vehicle, the floor panel is formed of a thin iron-based metal, so that it is vibrated slightly by road noise, for example, and a sound absorbing material is disposed. It has been newly found that the distribution of the air velocity (particle velocity) in the space is different in the plane of the floor panel as the outer panel. That is, the vibrating floor panel has a belly part that is greatly displaced from the stationary state where it does not vibrate. Air velocity (ie particle velocity) will move.

  The present invention has been made in view of the above circumstances, and its purpose is to appropriately adjust the surface density of the sound absorbing material in the plane of the floor panel in consideration of the difference in particle velocity in the plane of the floor panel. The object is to provide a sound insulation structure for a vehicle floor that can satisfy both sound insulation and weight reduction.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1,
The floor panel has a floor area surrounded by strength members, one is long and the other is short,
A high-rigidity portion extending in the short direction is formed in the floor region, and a square panel region and other regions partitioned by the high-rigidity portion are formed in the floor region,
On the panel region, a double wall structure is formed by disposing a floor carpet via a sound absorbing material as an intermediate layer,
The sound-absorbing material in the panel region has a high-density region and a low-density region having a smaller surface density than the high-density region in plan view,
The high-density region is set as a central part in the center of the panel region,
The low density region is set as an annular region surrounding the central region;
It is like that.

  According to the above solution, compared to the case where the density of the sound-absorbing material is made different in plan view (in the plane of the panel area) and the density is increased uniformly over the entire surface of the panel area, It is possible to reduce the weight while making the sound insulation equivalent. In addition, by making the panel area square by the high-rigidity part, the distribution of the particle velocity in the assumed panel area can be accurately reflected, and the sound insulation effect by the sound absorbing material is sufficiently ensured. be able to.

The solving technique preferred embodiments on the premise of the Ru der as described in the subclaims.

The high rigidity portion is a bead portion (corresponding to claim 2 ). In this case, it is preferable for preventing an increase in weight for securing the high-rigidity portion.

The high-rigidity portion is joined to the floor region, and is configured by a reinforcing member that is a separate member from the strength member that defines the floor region (corresponding to claim 3 ). In this case, by using the reinforcing member it can be simply configured high rigidity portion, also Ru can be utilized to floor panels having no high-rigidity portion as it effectively constitutes a high rigidity portion.

The high-density region is configured to be a square central portion set at the center of the panel region and a square annular portion surrounding the central portion (corresponding to claim 4 ). In this case, the density distribution of the sound absorbing material can appropriately reflect the particle velocity distribution in the panel region.

The strength member includes at least a tunnel portion, a side sill, and a cross member;
While the extending direction of the cross member is the long direction, the direction in which the side sill and the tunnel portion extend is the short direction.
(Corresponding to claim 5 ). In this case, what is generally employed as the structure of the vehicle floor panel and its peripheral portion can be used as it is.

In the floor region, the area of the other region is smaller than the area of the panel region,
A double wall structure having the floor carpet and the sound absorbing material is formed in the other region,
The surface density of the sound absorbing material in the other region is smaller than the surface density of the sound absorbing material in the high density region in the panel region and equal to or greater than the surface density of the sound absorbing material in the low density region .
(Corresponding to claim 6 ). In this case, the density of the sound-absorbing material in other regions can be reduced as much as possible, and the weight reduction can be further promoted accordingly.

  According to the present invention, both sound insulation and weight reduction can be satisfied.

Sectional drawing which shows the condition where the outer panel is vibrated while showing a double wall structure typically. The figure which shows the maximum value site | part and median value site | part of a particle velocity while showing the example of distribution of the area | region where a particle velocity is large and a small area | region when an outer side panel is vibrated. The figure which shows the example which made the surface density of a sound-absorbing material differ based on distribution of the particle velocity of FIG. The figure which shows the change of the particle velocity Vp when changing flow resistance (sigma) about each of the maximum value site | part of a particle velocity, and a median value site | part. The characteristic view which shows the relationship between the fabric weight of a sound-absorbing material, particle velocity, and transmission loss . The process figure which shows the method of determining the surface density of the sound-absorbing material by this invention. The top view which shows the example which applied this invention to the floor panel part of a vehicle. X8-X8 line equivalent sectional drawing of FIG. The top view which shows the floor area | region shown by FIG. FIG. 10 is a cross-sectional view corresponding to line X10-X10 in FIG. 9;

  Hereinafter, embodiments of the present invention will be described. First, with reference to FIGS. 1 to 6, the difference in particle velocity in the plane of the panel in the double wall structure, and the surface density of the sound absorbing material according to the difference in particle velocity. The points that are different will be described. Thereafter, the description will be made in relation to the floor panel of the vehicle with reference to FIG.

  FIG. 1 schematically shows a double wall structure. In FIG. 1, 20 is an outer panel, 30 is an inner panel, and 40 is a sound absorbing material. The outer panel 20 and the inner panel 30 are arranged with a small gap (for example, about 10 to 30 mm). A space K is defined between the panels 20 and 30. The space K is filled with the sound absorbing material 40 without any gaps. The gap between the panels 20 and 30 is closed by the closing member 50 (the space K is a sealed space in which the outside is blocked or a substantially sealed space). Both panels 20 and 30 are square. In FIG. 1, when a case where a double wall structure is adopted for the floor panel is assumed, a soft steel plate having a thickness of, for example, about 0.6 mm can be used as the outer panel 20, and a floor carpet can be used as the inner panel 30. .

  Both the panels 20 and 30 are indicated by broken lines when they are stationary, and are maintained in a substantially parallel state. Incident sound (road noise when the outer panel 20 is a vehicle floor panel) is input to the outer panel 20. At this time, as shown by a solid line, the outer panel 20 is vibrated, and the inner panel 30 is also vibrated accordingly. Thus, due to the vibration of the panels 20 and 30, the volume of the space K changes in the plane of the outer panel 20 (inner panel 30), and the particle velocity (air velocity) in the space K is in the plane of the outer panel 20. Will be different.

  FIG. 2 shows the particle velocity distribution in the space K in two stages when the outer panel 20 is vibrated with the sound absorbing material 40 removed from the state of FIG. In FIG. 2, a region where the particle velocity Vp is large (in the embodiment, a region of 2.5 m / s or more) is shown as a white region, and a region where the particle velocity is small (a region where the particle velocity is less than 2.5 m / s in the embodiment). Are shown as hatched areas. Further, in FIG. 2, a part where the particle speed is the maximum value (for example, 5.0 m / s) is indicated by a reference symbol R1, and a part where the particle speed is a median value (for example, 2.5 m / s) is indicated by a reference numeral R2. It is.

  The higher the effect of reducing the particle velocity by the sound absorbing material 40, the higher the sound insulation effect. That is, the transmission of noise energy goes through the process of vibration of the outer panel → change to particle velocity → vibration of the inner panel → propagation into the room, so that the sound insulation effect is enhanced by reducing the particle velocity with the sound absorbing material 40. be able to.

  Here, the greater the surface density of the sound absorbing material 40, the greater the flow resistance (resistance for reducing the particle velocity), and the higher the sound insulation effect. Moreover, if the same sound insulation effect is obtained, the surface density of the sound absorbing material 40 can be reduced as the particle velocity is reduced. Therefore, based on the two-stage distribution of the particle velocity obtained as shown in FIG. 2, the surface density of the sound absorbing material 40 is increased in the region where the particle velocity is high, and the surface of the sound absorbing material 40 is displayed in the region where the particle velocity is low. The density can be reduced. That is, it is possible to reduce the weight by setting the portion where the surface density is reduced while equalizing the sound insulation in the surface of the outer panel 20.

  In FIG. 3, based on the particle velocity distribution shown in FIG. 2, the region M1 in which the surface density of the sound absorbing material 40 is increased is outlined, and the region M2 in which the surface density is decreased is hatched. . The area | region M1 is set to two places, the square center part (square in embodiment) and the square cyclic | annular part surrounding this center part. The region M <b> 2 has two locations, a square (square in the embodiment) annular portion located between the two regions M <b> 1 and a square annular portion located at the peripheral edge of the outer panel 1.

  Next, an example of setting a large surface density in the region M1 will be described. First, the particle velocity maximum value portion R1 and the median value portion R2 are selected from the particle velocity distribution shown in FIG. Then, the particle velocity Vp (change) when the flow resistance σ is increased from 0 is acquired for each of the two parts R1 and R2. FIG. 4 shows an example of the correlation between the particle velocity Vp thus obtained and the flow resistance σ. In FIG. 4, the broken line is for the maximum value region R1, and the solid line is for the median value region R2.

In FIG. 4, initially, in both the parts R1 and R2, the particle velocity Vp is greatly reduced as the flow resistance increases, but the flow resistance σ is 0.03 (the unit is MPa · s / m ²⁾ In this explanation, the unit is omitted), and the decrease in the particle velocity Vp accompanying the increase in the flow resistance σ becomes extremely small, and the flow resistance σ is increased from around 0.05 to 0.06. However, the particle velocity Vp is hardly reduced.

  For each of the regions R1 and R2, even if the flow resistance σ is larger than 0.06, the particle velocity Vp cannot be substantially decreased (the function of decreasing the particle velocity Vp by the sound absorbing material 40). Saturation or limit). Accordingly, when the particle velocities Vp are the same under the condition that the flow resistances σ are the same for each of the portions R1 and R2, the predetermined target value VpT is set. The flow resistance σ at the target value VpT is set as the flow resistance required in the area M1 with a large surface density shown in FIG. 3 (sound insulation is sufficiently ensured at the portion where the particle velocity Vp is maximum).

Here, FIG. 5 shows the relationship between the basis weight (corresponding to the surface density and weight) of the sound absorbing material 40 and the transmission loss (degree of noise level reduction). As is clear from FIG. 5, the basis weight necessary to obtain the same transmission loss needs to be increased as the particle velocity increases. That is, when a certain transmission loss δ is obtained, the basis weight can be reduced when the particle velocity Vp is smaller than when the particle velocity Vp is large, and the difference is the weight difference (weight reduction) of the sound absorbing material 40. ). In FIG. 5, the characteristic of Vp · large corresponds to the maximum value of the detected particle velocity Vp (for example, 5 m / s), and the characteristic of Vp · small represents the median value of the detected particle velocity Vp (for example, 2.5 m / s).

  As described above, the basis weight of the sound absorbing material 40 is set based on the flow resistance (0.06 in the embodiment) required for the region M1 having a high particle velocity.

When the basis weight set for the region M1 is β1, a predetermined transmission loss (corresponding to δ in FIG. 5) corresponding to this is determined from a characteristic line (solid line in FIG. 5) showing the particle velocity Vp as large. . Then, the basis weight β2 of the sound absorbing material 40 in the region M2 is determined as the basis weight when the predetermined transmission loss δ is reached, based on the characteristic line (the broken line in FIG. 5) when the particle velocity Vp is small. Thereby, it can be set as the same transmission loss (same sound-insulation performance) by area | region M1 and M2. In addition, by considering the particle velocity at the median portion X2, it is preferable to sufficiently ensure sound insulation in the region M2 where the particle velocity is low.

  FIG. 6 shows a process for setting the aforementioned areas M1 and M2 and setting the surface density of the sound absorbing material 40 for the areas M1 and M2. FIG. 6 is a synthesis of the above description. In the following description, Q indicates a step.

  First, in Q1, the outer panel 20 is vibrated at a predetermined frequency (for example, vibration by an acoustic speaker) in a state where the sound absorbing material 40 is not present in the double wall structure, and the distribution of the particle velocity Vp at that time is as follows. (The particle velocity is detected using a particle velocity sensor by acquiring a map as shown in FIG. 2). In the process of Q1, for example, in the case of sound insulation measures for the rear seat portion of the vehicle floor panel, the floor panel as the outer panel 20 may be vibrated at, for example, 900 Hz, and the particle velocity distribution by this vibration is simulated. It can be obtained by.

  Thereafter, in Q2, a region M1 where the particle velocity is high and a region M2 where the particle velocity is small are set with a predetermined value serving as a threshold value (map setting as shown in FIG. 3).

  In Q3, the maximum value region R1 and the median value region R2 of the particle velocity Vp are selected. Thereafter, in Q4, the relationship of the particle velocity Vp when the flow resistance σ is increased from 0 is acquired for both the parts R1 and R2 (acquisition by simulation by acquiring characteristics as shown in FIG. 4). be able to).

  In Q5, the flow resistance value σ when the particle velocity Vp decreases to the target value VpT at which the particle velocity Vp is substantially the same is determined for each of the regions R1 and R2 from the acquired characteristics as shown in FIG. (0.06 in the embodiment). Thereafter, in Q6, the first surface density (corresponding to β1 in FIG. 5) of the sound absorbing material 40 that satisfies the flow resistance σ determined in Q5 is determined. The first surface density determined by Q6 is the surface density of the region M1 in the sound absorbing material 40.

In Q7, based on the characteristics shown in FIG. 5, for when the particle velocity Vp is small, the second surface density for transmission loss and an equivalent transmission loss δ when the first surface density particle velocity Vp is large and Is determined. This second surface density is the surface density of the region M2 in the sound absorbing material 40.

  Next, an example in which the double-wall sound insulation structure is applied to a vehicle floor panel will be described with reference to FIGS. First, in FIG. 7, reference numeral 1 denotes a floor panel that constitutes a passenger compartment floor, which is for a vehicle having two rows of front and rear seats. A rear floor panel 3 is connected to a rear portion of the floor panel 1 via a kick-up portion 2. A tunnel portion 4 bulging upward and extending in the front-rear direction is formed at the center of the floor panel 1 in the vehicle width direction. And the vehicle width direction edge part of the floor panel 1 is joined to the side sill 5 as a strength member extended in the front-back direction. Although not shown in the drawing, a cross member extending in the vehicle width direction is joined to the bottom of the kick-up portion 2, and the bottom portion of the kick-up portion 2 has high rigidity (strength).

  On the floor panel 1, two sets of front and rear cross members 11 and 12 extending in the vehicle width direction are joined. The front cross member 11 is configured such that a front seat is attached to the tunnel member 4 and the side sill 5. The rear cross member 12 is configured to be attached with a seat for the rear seat, and connects the tunnel portion 4 and the side sill 5. In the figure, 7 is a pair of left and right front frames, and 8 is a dash panel that partitions the engine room and the vehicle compartment.

  A floor frame 15 that extends obliquely in the front-rear direction is joined to the floor panel 1 between the pair of left and right side sills 5. The floor frame 15 has a front end connected to the rear portion of the front frame 7 directly or indirectly via a strength member, and a rear end connected to the rear portion of the side sill 5. That is, the floor frame 15 constitutes a load path through which a load from the front input to the front frame 7 is transmitted. The floor frame 15 has two upper and lower closed cross sections formed by joining a hat-shaped strength member to the upper surface and the lower surface of the floor panel 1 on the front side of the cross member 11. Also, the rear portion is formed with one closed cross section by joining a hat-shaped strength member only to the lower surface of the floor panel 1.

  The floor panel 1 has six panel portions that are susceptible to vibration due to road noise in a plan view by the pair of left and right side sills 5, the tunnel portion 4, and the cross members 11 and 12, and for each of these panel portions, A sound insulation structure with a double wall structure is adopted. Of the double wall structure, the structure of the left panel portion with respect to the rear seat is shown in FIGS. In FIG. 9, the left cross member 12, the tunnel portion 4, the kick-up portion 2, and the left side sill 5 correspond to the closing member 50 in FIG. 1.

  As shown in FIGS. 8 and 10, the double-wall sound insulation structure includes the floor panel 1 corresponding to the outer panel 20 and the floor carpet 16 corresponding to the inner panel 30, and the sound absorbing material 17 ( The sound absorbing material 40 in FIG. 1 is filled. The sound absorbing material 17 is made of fiber. Further, the entire peripheral edge portion of the floor carpet 16 is sealed, and the space where the sound absorbing material 17 is disposed (corresponding to the space K in FIG. 1) is set to have a sealed structure as much as possible. And about this sound-absorbing material 17, according to the distribution of the particle velocity in the surface of the floor panel 1, it sets so that a surface density may differ. That is, the sound absorbing material 17 is divided into a portion having a high surface density and a portion having a low surface density, as shown in FIG.

  In the embodiment, two floor carpets 16 are provided on the left and right sides with the tunnel portion 4 as a boundary. However, the left and right floor carpets 16 with the tunnel portion 4 as a boundary can be divided into three pieces before and after the cross members 11 and 12 as a boundary. In the embodiment, the floor carpet 16 is set at a position lower than the cross member 12, but the floor carpet 16 may be set at a position higher than the cross member 12 (the floor panel 1 and the floor carpet 16). The vertical spacing of the is increased and the sound insulation is improved accordingly).

  Here, for convenience of explanation, the left side panel portion of the floor panel 1 for the rear seat (respectively surrounded by the left cross member 12, the tunnel portion 4, the kick-up portion 2, and the left side sill 5 as strength members) This portion will be described as the floor region F1 (the same configuration is adopted in the right panel portion for the rear seat). As shown in FIGS. 7 and 9, the floor region F <b> 1 has a rectangular shape that is long in the vehicle width direction and short in the front-rear direction in plan view.

  In the floor region F1, a bead portion 18 is formed as a highly rigid portion by partially expanding the floor panel 1 upward, for example. The bead portion 18 extends in the short direction (front-rear direction) of the floor region F <b> 1 and is parallel to the tunnel portion 4 and the side sill 5. The bead portion 18 extends substantially over the entire length in the short direction of the floor region F1, but constitutes a “node” of vibration when the floor region is vibrated by road noise.

  The floor region F1 is partitioned by the bead portion 18 into a panel region P1 and another region P2 in the vehicle width direction. The panel region P1 is shown with double hatching in FIG. 7, is square as shown in FIG. 9, and has a larger area than the other regions P2.

The surface density of the sound absorbing material 17 in the panel region P1 is set to be the same as that shown in FIG. That is, in the panel region P1, the sound absorbing material 17 has a high density region M1 and a low density region M2. Thus, in the panel area | region P1, since the low density area | region M2 is set, ensuring sound-insulating property enough, weight reduction can be achieved by this. In the embodiment, the surface density in the high density region M1 is 0.9 kg / m ² and the surface density in the low density region M2 is 0.6 kg / m ² .

  The other region P2 has a smaller area than the panel region P1, and a particle velocity generated due to road noise is smaller than that of the panel region. Therefore, the surface density of the sound absorbing material 17 in the other region P2 can be set to be the same as that of the low density region M2 in the panel region P1, and the weight can be further reduced accordingly. In addition, the surface density of the sound absorbing material 17 in the other region P2 can be set to an intermediate density between the surface density in the region M1 and the surface density in the region M2.

  8 to 10, the panel portion on the left side of the rear seat in the floor panel 1 has been described, but the same setting is made for the panel portion on the right side of the rear seat. Further, other panel portions other than the rear seat are set similarly. That is, the two left and right panel portions on the front side of the cross member 11 and the left and right two panel portions positioned between the cross members 11 and 12 may be set as shown in FIGS. it can.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. Instead of forming the bead portion 18, a lightweight reinforcing member may be joined to the floor panel 1 (since it is only necessary to constitute a “node” of vibration, it can be made of synthetic resin in order to reduce the weight as much as possible. ). The frequency at the time of excitation for obtaining the particle velocity distribution can be appropriately selected as a frequency (frequency range) that requires reduction. It is also possible to obtain particle velocity distributions for a plurality of frequencies that are greatly different from each other (for example, differ by 100 Hz or more), and to classify the particle velocity regions based on the particle velocity distributions for the plurality of frequencies. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention can reduce the weight of the vehicle while ensuring the quietness of the room by a simple method of adjusting the density of the sound absorbing material.

1: Floor panel 2: Kick-up part 4: Tunnel part 5: Side sill 11: Cross member 12: Cross member 16: Floor carpet 17: Sound absorbing material 18: Bead part 20: Outer panel 30: Inner panel 40: Sound absorbing material K: Space M1: Region where flow resistance is large M2: Region where flow resistance is small R1: Maximum portion of particle velocity R2: Median portion of particle velocity β1: Weight of sound absorbing material in region where particle velocity is large β2: Particle velocity is Sound absorption material weight per unit area F1: Floor area P1: Panel area P2: Other area

Claims (6)

The floor panel has a floor area surrounded by strength members, one is long and the other is short,
A high-rigidity portion extending in the short direction is formed in the floor region, and a square panel region and other regions partitioned by the high-rigidity portion are formed in the floor region,
On the panel region, a double wall structure is formed by disposing a floor carpet via a sound absorbing material as an intermediate layer,
The sound-absorbing material in the panel region has a high-density region and a low-density region having a smaller surface density than the high-density region in plan view,
The high-density region is set as a central part in the center of the panel region,
The low density region is set as an annular region surrounding the central region;
A sound insulation structure for a vehicle floor. Oite to claim 1,
The sound insulation structure for a vehicle floor, wherein the high-rigidity portion is a bead portion. In claim 1 or claim 2 ,
The sound insulation structure for a vehicle floor, wherein the high-rigidity portion is joined to the floor region and is configured by a reinforcing member that is a member different from the strength member that partitions the floor region. In any one of Claims 1 thru | or 3 ,
The sound insulation structure for a vehicle floor, characterized in that the high-density region is a square central portion set at a central portion of the panel region and a square annular portion surrounding the central portion. In any one of Claims 1 thru | or 4 ,
The strength member includes at least a tunnel portion, a side sill, and a cross member;
While the extending direction of the cross member is the long direction, the direction in which the side sill and the tunnel portion extend is the short direction.
A sound insulation structure for a vehicle floor. In any one of Claims 1 thru | or 5 ,
In the floor region, the area of the other region is smaller than the area of the panel region,
A double wall structure having the floor carpet and the sound absorbing material is formed in the other region,
The surface density of the sound absorbing material in the other region is smaller than the surface density of the sound absorbing material in the high density region in the panel region and equal to or greater than the surface density of the sound absorbing material in the low density region .
A sound insulation structure for a vehicle floor.

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