JP2002225754A - Floor structure of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a floor structure of an automobile capable of effectively reducing noise for an occupant in a cabin considering the incoming of the noise from a driving system, etc. SOLUTION: A resonance reducing means for incoming vibration of a rear engine mount fitting part 17 is provided on parts 19, 20, 22 and 23 of a substantially horizontal part and both longitudinal walls of a tunnel part 7 forward of a second cross member, and a resonance reducing means for incoming vibration of a center bearing fitting part 16 is provided on parts 14, 18 and 21 surrounded by the second cross member 2 and a seat cross member 8 between both side members including the substantially horizontally part and the longitudinal walls of the tunnel part 7. Resonance caused by the vibration of the driving system coming from the rear engine mount fitting part 17, the center bearing fitting part 16, etc., is reduced, and the vibration and the noise transmitted to the occupant in the cabin are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile floor structure, and more particularly to an automobile floor structure for reducing noise generated by an input from a driving system.

[0002]

2. Description of the Related Art A floor structure of an automobile has been conventionally used to reduce vibration and noise (road noise) transmitted from various sources into a vehicle interior, such as resonance of a suspension device during driving and cavity resonance of a tire. Various structures have been proposed.

For example, as a conventional automobile floor structure, as disclosed in Japanese Patent Application Laid-Open No. 2000-72041, a front body frame member on the front side of a vibration input point of vibration input from a rear suspension is disclosed. It is known that the vertical vibration resonance frequency with respect to the body frame on the rear side of the vehicle is set to a frequency apart from the vertical vibration resonance frequency of the rear suspension to reduce noise heard by occupants in the vehicle interior.

Further, as disclosed in Japanese Patent Application Laid-Open No. 9-202269, in order to reduce radiated sound radiated from a floor panel of an automobile due to road noise, a target frequency to be reduced is set. , Detecting the frequency and strain energy distribution of multiple vibration modes generated in the panel under constraints such as panel dimensions, materials, support conditions,
There is also known one in which the structural parameters of the panel are adjusted so that the frequency of the vibration mode having low radiation efficiency approaches the target frequency.

[0005]

In the above-mentioned conventional structure, there is a structure for reducing vibration and noise (road noise) transmitted to the vehicle interior due to vertical vibration input from a suspension device, cavity resonance of a tire, and the like. Proposed. However, the vibration and noise transmitted into the vehicle cabin are also caused by things that are not related to the suspension or tires, such as vibration and wind noise of the mounting part of the support member that supports the drive system. Therefore, when considering the entire floor, it was necessary to consider measures for these.

Accordingly, the present invention provides an automobile floor structure capable of effectively reducing noise heard by occupants in a vehicle cabin in consideration of an input from a drive system or the like.

[0007]

According to the first aspect of the present invention, a floor panel having a tunnel extending in the vehicle front-rear direction at a substantially central portion in the vehicle width direction is connected to floor panels on both sides of the tunnel. A side member extending in the vehicle longitudinal direction, a first cross member joined to a substantially central portion of the floor panel in the vehicle longitudinal direction and extending in the vehicle width direction, and a vehicle joined to the floor panel behind the first cross member. A second cross member extending in the width direction; a third cross member joined to the floor panel behind the second cross member and extending in the vehicle width direction; and a rear engine mount provided on a lower surface of a tunnel portion in front of the first cross member. An automobile floor structure comprising: a mounting portion; and a center bearing mounting portion provided on a lower surface of a tunnel portion between a second cross member and a third cross member. A resonance reducing means for vibration input of the rear engine mount mounting portion is provided in a portion of the tunnel portion substantially forward of the second cross member of the horizontal portion and both side vertical walls, and both sides including the substantially horizontal portion of the tunnel portion and both side vertical walls are provided. It is characterized in that resonance reducing means for vibration input of the center bearing mounting portion is provided in a portion sandwiched between the second cross member and the third cross member between the members.

According to the second aspect of the present invention, as the resonance reducing means for the vibration input of the rear engine mount mounting portion according to the first aspect, the second cross member of the substantially horizontal portion of the tunnel portion and the vertical walls on both sides is used. The (1,1) mode natural frequency of the local out-of-plane deformation of the front portion is lower than the resonance frequency of the rear engine mount mounting portion and lower than the pump noise frequency of the transmission oil pump disposed around. The height is set high, and a local surface of a portion of the substantially horizontal portion of the tunnel portion and a portion of the vertical wall on both sides sandwiched between the second cross member and the third cross member is used as means for reducing resonance with respect to the vibration input of the center bearing mounting portion. The (1,1) mode natural frequency of the external deformation is set to be equal to or higher than the differential noise frequency of the differential device arranged around,
In addition, the (1,1) mode natural frequency of local out-of-plane deformation of a portion sandwiched between the second cross member and the third cross member between both side vertical walls of the tunnel portion and the side member is determined by the differential noise. The frequency is set to be higher than the frequency or lower than the resonance frequency of the center bearing mounting portion.

According to a third aspect of the present invention, a local out-of-plane deformation of a portion in front of the substantially horizontal portion of the tunnel portion and the second cross members of the vertical walls on both sides according to the second aspect is provided. )
The mode natural frequency is set in a range of 400 to 600 Hz, and local out-of-plane deformation of a portion between the second cross member and the third cross member of the substantially horizontal portion and both side vertical walls of the tunnel portion. The (1,1) mode natural frequency of
The frequency is set to 700 Hz or more, and the local out-of-plane deformation of a portion sandwiched between the second cross member and the third cross member between the vertical walls on both sides of the tunnel portion and the side members is (1, 1).
1) Set the mode natural frequency to 700 Hz or higher or 150
It is characterized in that it is set in the range of -250 Hz.

[0010] In the invention of claim 4, claims 1 to 3 are provided.
As a means for reducing resonance with respect to the vibration input of the rear engine mount mounting portion described in the above, flat portions are provided on the left and right side edges of the substantially horizontal portion of the tunnel portion and the front portions of the both side vertical walls with respect to the second cross member. The portions between the portions are formed in a substantially (1,1) mode natural vibration mode shape, and as a means for reducing resonance with respect to the vibration input of the center bearing mounting portion, the substantially horizontal portion of the tunnel portion and the second side walls of the vertical walls on both sides are used. The portions sandwiched between the cross member and the third cross member are each formed in a substantially (1,1) mode natural vibration mode shape, and the second cross member between both side vertical walls of the tunnel portion and the side member is formed. The portion sandwiched between the member and the third cross member is provided with flat portions on both left and right side edges, and the portion between these flat portions is formed in a natural vibration mode shape of a substantially (1, 3) mode. It is a symptom.

In the invention of claim 5, claims 1 to 4 are provided.
A means for reducing road noise or wind noise is provided in a portion sandwiched between the side member described in (1) and a side sill which is a skeletal member of a vehicle side portion.

According to a sixth aspect of the present invention, as a means for reducing road noise or wind noise according to the fifth aspect, a local portion of a portion sandwiched between the side member and a side sill which is a skeletal member of a vehicle side portion. Out-of-plane deformation (1,
1) The mode natural frequency is set lower than the left-right bending resonance frequency of the side member or higher than the frequency of wind noise that enters the vehicle interior through the floor panel.

According to a seventh aspect of the present invention, a local out-of-plane deformation of a portion sandwiched between the side member according to the sixth aspect and a side sill, which is a skeletal member of a vehicle side portion, is provided.
1) Set the mode natural frequency to 150 Hz or less, or
It is characterized in that the frequency is set to 600 Hz or higher.

According to the invention of claim 8, claims 5 to 7 are provided.
As a means for reducing road noise or wind noise, the portions sandwiched between the side member and the side sill, which is a frame member on the side of the vehicle, are each formed into a substantially (1, 1) mode natural vibration mode shape. It is characterized by having.

According to the ninth aspect of the present invention, the first to eighth aspects are provided.
Wherein a means for reducing road noise or a means for reducing resonance with respect to vibration input of a rear engine mount mounting portion is provided in a portion forward of the second cross member between the side member and the vertical wall on both sides of the tunnel portion. It is characterized by.

According to a tenth aspect of the present invention, as the resonance reducing means for the road noise or the vibration input of the rear engine mount mounting portion according to the ninth aspect, between the side member and the vertical walls on both sides of the tunnel portion. (1, 1) of local out-of-plane deformation of a portion ahead of the second cross member
1) The mode natural frequency is in a range lower than the left-right bending frequency of the side member or lower than the resonance frequency of the rear engine mount mounting portion, and the pump noise frequency of a transmission oil pump disposed around the periphery. It is characterized in that it is set in any of the higher ranges.

According to the eleventh aspect of the present invention, in the tenth aspect,
The local (1,1) mode natural frequency of a local out-of-plane deformation of a portion forward of the second cross member between the side member and the vertical wall on both sides of the tunnel portion is set to 150H.
z or less, or set in the range of 400 to 600 Hz.

According to the twelfth aspect of the present invention, the ninth to nineteenth aspects of the present invention are described below.
As a means for reducing road noise or a means for reducing resonance in response to vibration input of a rear engine mount mounting portion according to claim 11, a portion forward of the second cross member between the side member and both side vertical walls of the tunnel portion,
It is characterized in that flat portions are provided on both left and right side edges, and a space between these flat portions is formed into a substantially (1, 3) mode natural vibration mode shape.

The (nm) mode is defined as: n: the number of antinodes of vibration in a predetermined direction (n = 1, 2, 3,...), M: vibration in a direction perpendicular to the predetermined direction. Number of belly (m = 1,
2, 3, ..).

In the (pq) mode shape, the initial shape (non-vibrating state) of the panel has p irregularities (curved shapes) in a predetermined direction and a direction perpendicular to the predetermined direction, respectively. , Q. On the other hand, the natural frequency of the (nm) mode is a natural frequency in a case where the number of antinodes of vibration in a predetermined direction during vibration and in the direction perpendicular to the predetermined direction is n and m, respectively. pointing.

Therefore, even if the panel has an initial shape of (pq) mode, the deformation from the initial shape is as follows:
In some cases, the vibration may occur at the natural frequency of the (nm) mode (here, n ≠ p, m ≠ q), and the setting is performed in consideration of these cases.

[0022]

According to the first aspect of the present invention, the resonance reducing means for the vibration input of the rear engine mount mounting portion is provided in the substantially horizontal portion of the tunnel portion and in a portion forward of the second cross members of the vertical walls on both sides. In addition, resonance reducing means for vibration input of the center bearing mounting portion is provided in a portion sandwiched between the second cross member and the third cross member between both side members including the substantially horizontal portion and both side vertical walls of the tunnel portion. Therefore, it is possible to reduce the resonance caused by the vibration of the drive system input from the rear engine mount mounting portion, the center bearing mounting portion, or the like, and reduce the vibration and noise transmitted to the occupant in the vehicle cabin.

According to the invention described in claim 2, according to claim 1
In addition to the effect of (1), as a means for reducing the resonance with respect to the vibration input of the rear engine mount mounting portion, the local out-of-plane deformation of the portion in front of the substantially horizontal portion of the tunnel portion and the second cross members of the vertical walls on both sides is obtained. ) The mode natural frequency is lower than the resonance frequency of the rear engine mount mounting part, and
Since it is set higher than the pump noise frequency of the transmission oil pump located in the periphery, a place where the radiation efficiency is low at the resonance frequency due to the vibration input of the rear engine mount mounting part in the corresponding part is secured, and the vibration and noise Can be effectively reduced.

As a means for reducing the resonance with respect to the vibration input of the center bearing mounting portion, a local surface of a portion of the tunnel portion sandwiched between the second cross member and the third cross member of the substantially horizontal portion and both side vertical walls. The (1,1) mode natural frequency of the external deformation is set to be equal to or higher than the differential noise frequency of the differential device arranged in the periphery, and the second cross member and the second cross member between the side wall and the vertical wall on both sides of the tunnel portion are set. The (1, 1) mode natural frequency of the local out-of-plane deformation of the portion sandwiched between the three cross members is set to be higher than the differential noise frequency or lower than the resonance frequency of the center bearing mounting portion. It is possible to secure a place where the radiation efficiency is low at the resonance frequency due to the vibration input of the center bearing mounting part in the part, and effectively reduce vibration and noise. That.

According to the third aspect of the present invention, the (1,1) mode natural frequency of the local out-of-plane deformation of a portion in front of the substantially horizontal portion of the tunnel portion and the second cross members of the vertical walls on both sides is determined by: (1, 1) is set in the range of 400 to 600 Hz, and the local out-of-plane deformation of a portion of the substantially horizontal portion of the tunnel portion and both vertical walls sandwiched between the second cross member and the third cross member. The mode natural frequency is set to 700 Hz or more, and local out-of-plane deformation of a portion sandwiched between the second cross member and the third cross member between both side vertical walls and the side member of the tunnel portion is set. Since the (1,1) mode natural frequency is set to 700 Hz or more or in the range of 150 to 250 Hz, the same operation and effect as in claim 2 can be obtained.

According to the fourth aspect of the present invention, in addition to the effects of the first to third aspects, as a means for reducing resonance with respect to vibration input of the rear engine mount mounting portion, the second portion of the substantially horizontal portion of the tunnel portion and the vertical walls on both sides are provided. Flat portions are provided on the left and right side edges of the front portion of the cross member, respectively, and a space between these flat portions is formed in a substantially (1, 1) mode natural vibration mode shape, and vibration input of the center bearing mounting portion is performed. As a means for reducing the resonance, the portions of the tunnel portion sandwiched between the second cross member and the third cross member of the substantially horizontal portion and the vertical walls on both sides are each formed into a substantially (1, 1) mode natural vibration mode shape. In addition, a portion sandwiched between the second cross member and the third cross member between both side vertical walls of the tunnel portion and the side member is provided with flat portions on both left and right edges, and the space between these flat portions is substantially ( , 3) that is formed on the natural vibration mode shape of the mode, with a simple structure without requiring tight tolerances in the panel machining accuracy can be properly adjust the natural vibration mode of the relevant sections.

According to the fifth aspect of the present invention, in addition to the effects of the first to fourth aspects, the portion between the side member and the side sill which is a frame member on the side of the vehicle is reduced in road noise or wind noise. Claim 1 because the means is provided.
In addition to measures against vibrations and sounds from the drive system in (4), resonance due to road noise and wind noise can be reduced, and vibrations and noise transmitted to occupants in the vehicle cabin can be reduced.

According to the invention of claim 6, in addition to the effect of claim 5, as a means for reducing road noise or wind noise, a portion sandwiched between the side member and the side sill, which is a frame member on the side of the vehicle. The (1,1) mode natural frequency of the local out-of-plane deformation is set lower than the left-right bending resonance frequency of the side member or higher than the frequency of wind noise that enters the vehicle interior through the floor panel. Therefore, it is possible to secure a place where the radiation efficiency at a frequency where the floor panel is likely to affect road noise or wind noise is reduced in the corresponding portion, and it is possible to effectively reduce vibration and noise.

According to the seventh aspect of the present invention, the (1,1) mode natural frequency of local out-of-plane deformation of a portion sandwiched between the side member and the side sill which is a skeletal member of the vehicle side portion. Is set to 150 Hz or less, or 600 Hz or more, so that the same operation and effect as in claim 6 can be obtained.

According to the eighth aspect of the present invention, in addition to the effects of the fifth to seventh aspects, as a means for reducing road noise or wind noise, the side member is sandwiched between the side sill which is a frame member on the side of the vehicle. Each part is abbreviated (1,
1) Since it is formed in the natural vibration mode shape of the mode,
It is possible to appropriately adjust the natural vibration mode at a corresponding location with a simple structure without requiring strict precision in panel processing.

According to the ninth aspect of the present invention, in addition to the effects of the first to eighth aspects, a road noise is provided at a portion forward of the second cross member between the side member and both side vertical walls of the tunnel portion. To reduce road noise and resonance due to vibration input of the rear mount mounting part, further reducing vibration and noise transmitted to occupants in the vehicle cabin. can do.

According to the tenth aspect of the present invention, in addition to the effect of the ninth aspect, both sides of the side member and the tunnel portion are provided as a means for reducing road noise or a means for reducing resonance with respect to vibration input of the rear engine mount mounting portion. The (1,1) mode natural frequency of the local out-of-plane deformation of the front part of the second cross member between the vertical member and the vertical wall is in a range lower than the left-right bending resonance frequency of the side member or the rear. Since it is set to a range lower than the resonance frequency of the engine mount mounting portion and higher than the pump noise frequency of the transmission oil pump disposed in the vicinity, a means for reducing road noise or a rear portion in the corresponding portion. Secure a place where the radiation efficiency at the resonance frequency due to the vibration input of the engine mount mounting part becomes low, Dynamic and noise can be effectively reduced further.

[0033] According to the eleventh aspect of the present invention, the local out-of-plane deformation of the portion forward of the second cross member between the side member and the vertical walls on both sides of the tunnel portion is (1, 1).
1) Set the mode natural frequency to 150 Hz or less, or
Since the frequency is set in the range of 400 to 600 Hz, the same operation and effect as those of the tenth aspect can be obtained.

According to the twelfth aspect, the ninth to the ninth aspects
In addition to the effect of the first aspect, as a means for reducing road noise or a means for reducing resonance in response to vibration input of the rear engine mount mounting portion, a portion forward of the second cross member between the side member and both vertical walls of the tunnel portion. The flat part is provided on both left and right side edges, and the space between these flat parts is formed in a substantially (1,3) mode natural vibration mode shape. With a simple structure, the natural vibration mode at the corresponding location can be appropriately adjusted.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) A first embodiment of a floor structure of an automobile to which the present invention is applied will be described with reference to FIGS.

FIG. 1 is a perspective view showing a floor structure of an automobile, and FIG. 2 is a view showing a floor structure of a first embodiment of the present invention. FIG. 3 shows the panel shape of each part.

First, the configuration will be described. Reference numeral 6 denotes a floor panel having a tunnel portion 7 extending in the vehicle front-rear direction at a substantially central portion in the vehicle width direction. Side members 3 extending in the vehicle front-rear direction are provided on the lower surfaces of the floor panels 6 on both sides of the tunnel portion 7. Is connected. Reference numeral 4 denotes a side sill of a vehicle longitudinal frame member connected to the floor panel 6 on both sides of the side member 3.

Further, in the vehicle width direction of the floor panel 6, a first cross member 1 joined to a substantially central portion in the vehicle front-rear direction, a second cross member 2 behind the first cross member 1, A sheet cross member 8 as three cross members is arranged.

A rear engine mount mounting portion 17 is provided on a lower surface of the tunnel portion 7 in front of the first cross member 1.
A center bearing mounting portion 16 is provided on the lower surface of the tunnel portion 7 between the second cross member 2 and the seat cross member 8.

In the floor structure of the automobile configured as described above, measures are taken to reduce vibration and noise transmitted to the occupants in the passenger compartment.

In the floor structure of an automobile to which the present invention is applied, the vibration of the rear engine mount mounting portion 17 is provided on the substantially horizontal portions 22 and 23 of the tunnel portion 7 and the vertical walls 19 and 20 in front of the second cross member 2. A resonance reducing means for input is provided, and the substantially horizontal portion 21 and both side vertical walls 18 of the tunnel portion 7 sandwiched between the second cross member 2 and the seat cross member 8 and the two side vertical walls 18 and the side members 3 are formed. The panel 14 sandwiched between the second cross member 2 and the seat cross member 8 is provided with resonance reducing means for the vibration input of the center bearing mounting portion.

More specifically, as a means for reducing the resonance with respect to the vibration input of the rear engine mount mounting portion 17, the substantially horizontal portions 22, 23 of the tunnel portion 7 in front of the second cross member.
And the local out-of-plane deformation of the vertical walls 19, 20 on both sides (1,
1) A range in which the mode natural frequency is lower than the resonance frequency (600 to 700 Hz) of the rear engine mount mounting portion and higher than the pump noise frequency (250 to 400 Hz) of the transmission oil pump arranged in the vicinity ( 400 to 600 Hz), and in this embodiment, the portions 19, 20, 22, 23 are used.
The (1,1) mode natural frequency of the local out-of-plane deformation of
It is set to 500 ± 50 Hz.

As a means for reducing the resonance of the center bearing mounting portion 16 against vibration input, the tunnel portion 7 sandwiched between the second cross member 2 and the seat cross member 8 is used.
The (1,1) mode natural frequency of the local out-of-plane deformation of the substantially horizontal portion 21 and the vertical walls 18 on both sides is set to be equal to or higher than the differential noise frequency (700 Hz) of the differential device arranged around the tunnel portion. The (1,1) mode natural frequency of the local out-of-plane deformation of the panel 14 sandwiched between the second cross member 2 and the sheet cross member 8 between the vertical walls 18 on both sides of the panel 7 and the side members 3 is described above. It is set in a range (150-250 Hz) which is higher than a differential noise upper limit frequency (700 Hz) or lower than a resonance frequency (250-300 Hz) of the center bearing mounting portion 16.
In this embodiment, the (1, 1) mode natural frequency of the local out-of-plane deformation of the portion is set to 800 Hz or more in the substantially horizontal portion 21 of the tunnel portion 7 and the vertical walls 18 on both sides.
In No. 4, the resonance frequency is set to about 200 Hz lower than the resonance frequency of the center bearing mounting portion 16.

FIG. 3 shows the shape of the panel at each of these portions. The substantially horizontal portion 22 of the tunnel portion 7, which is located around the rear engine mount mounting portion 17 and forward of the second cross member 2, is shown. , 23 and vertical wall 1 on both sides
As shown in FIG. 3A, reference numerals 9 and 20 respectively denote substantially flat portions 26 on both left and right side edges and between the flat portions 26.
1) Formed in a natural vibration mode shape 27 of the mode.

The substantially horizontal portion 21 and both side vertical walls 18 of the tunnel 7 around the center bearing mounting portion 16 and between the second cross member 2 and the seat cross member 8 are shown in FIG. As shown in (b), each of the panels 14 is formed in a natural vibration mode shape of substantially (1, 1) mode, and is sandwiched between the vertical walls 18 and the side members 3 on both sides.
As shown in FIG. 3 (c), flat portions 25
And a space between these flat portions 25 is formed into a natural vibration mode shape 24 of a substantially (1, 3) mode.

FIG. 4 is a graph showing an example of the noise reduction effect of the floor structure of the first embodiment, and shows the noise at the occupant position in the passenger compartment when the center bearing mounting portion 17 is vibrated. A polygonal line X1 in the graph indicates noise in the conventional floor structure, and a polygonal line Y1 indicates noise in the floor structure to which the present invention is applied. As is apparent from FIG. 4, in the floor structure to which the present invention is applied, the resonance frequency (250 to 3
(00 Hz) It can be seen that the noise near α is reduced.

According to the structure of the first embodiment described above, the rear engine mount mounting portion 17 is provided on the substantially horizontal portion of the tunnel portion 7 and the front portions 19, 20, 22, and 23 of the second cross members of the vertical walls on both sides. In addition to providing a resonance reducing means for vibration input, the portions 14, 18, 21 sandwiched between the second cross member 2 and the sheet cross member 8 between the side members including the substantially horizontal portion of the tunnel portion 7 and both side vertical walls are provided. Since the resonance reducing means for the vibration input of the center bearing mounting portion 16 is provided, the resonance due to the vibration of the drive system input from the rear engine mount mounting portion 17 or the center bearing mounting portion 16 or the like is reduced, and the occupant in the vehicle compartment is reduced. Vibration and noise transmitted to the vehicle can be reduced.

In particular, in the first embodiment, as a means for reducing the resonance with respect to the vibration input of the rear engine mount mounting portion 17, local out-of-plane portions of the substantially horizontal portions 22, 23 of the tunnel portion 7 and the vertical walls 19, 20 on both sides are used. The (1, 1) mode natural frequency of the deformation is in a range lower than the resonance frequency of the rear engine mount mounting portion and higher than the pump noise frequency of a transmission oil pump (not shown) arranged around the 500. Because it is set to ± 50Hz,
Vibration and noise due to vibration input of the rear engine mount mounting portion 17 in the corresponding portions 19, 20, 22, and 23 can be effectively reduced.

As a means for reducing resonance with respect to the vibration input of the center bearing mounting portion 16, the (1,1) mode natural frequency of the local out-of-plane deformation of the substantially horizontal portion 21 and the side vertical walls 18 of the tunnel portion 7 is used. Is set to 800 Hz which is equal to or higher than the differential noise frequency of the differential device arranged in the periphery.
In addition to the above, the local out-of-plane deformation of the panel 14 between the vertical walls 18 on both sides and the side members 3 is (1, 1).
Since the mode natural frequency is set at about 200 Hz lower than the resonance frequency of the center bearing mounting portion 16,
A place where the radiation efficiency is low at the resonance frequency due to the vibration input of the center bearing mounting portion 16 in the corresponding portions 14, 18, 21 can be secured, and the vibration and noise can be effectively reduced.

In this embodiment, the panel 14
The natural frequency of the (1,1) mode of the local out-of-plane deformation is lower than the resonance frequency of the center bearing mounting part 16 by 20.
Although the example in which the frequency is set to about 0 Hz is shown, the (1, 1) mode natural frequency of the local out-of-plane deformation of the panel 14 is set to 700 Hz or more, which is the differential noise frequency of the differential device arranged in the periphery. Thus, a place where the radiation efficiency becomes low at the resonance frequency due to the vibration input of the center bearing mounting portion 16 in the panel 14 may be secured, and the vibration and noise may be effectively reduced.

In this embodiment, since the area of the substantially horizontal portion 21 of the tunnel portion 7 and the vertical walls 18 on both sides is small, an example in which the differential noise frequency is set to 700 Hz or more is shown. Even when the (1,1) mode natural frequency of the local out-of-plane deformation of the vertical wall 18 is set in the range of 150 to 250 Hz similarly to the panel 14, the input from the center bearing mounting portion 16 is Needless to say, it is advantageous.

On the other hand, portions 19, 20, 2 forward of the substantially horizontal portion of the tunnel portion 7 and the second cross members of the vertical walls on both sides.
2, 23 are provided with flat portions 27 on both left and right side edges, respectively.
The space between these flat portions 27 is formed in a natural vibration mode shape 16 of a substantially (1,1) mode, and the second cross member 2 and the sheet cross member 8 of the substantially horizontal portion and both side vertical walls of the tunnel portion 7 are formed. Are formed into a substantially (1,1) mode natural vibration mode shape, and the panel 14 between the both vertical walls 18 and the side members 3 is formed on the left and right side edges. Flat portions 25 and these flat portions 2
The natural vibration mode shape 24 of approximately (1, 3) mode between 5
Therefore, it is possible to appropriately adjust the natural vibration mode at the corresponding location with a simple structure without requiring strict accuracy in processing accuracy of the panel.

(Second Embodiment) FIG. 5 shows a floor structure of a second embodiment to which the present invention is applied. In the second embodiment, a side member is added to the structure of the first embodiment. A means for reducing road noise or a means for reducing wind noise is provided in a portion sandwiched between the vehicle body 3 and the side sill 4 which is a frame member on the side of the vehicle. Vertical wall 1 on both sides
8, 19, and 20 and the substantially horizontal portions 21, 22, and 23 are the same as those in the above-described first embodiment, and therefore, the same reference numerals are given to the same portions, and redundant description will be omitted.

In the second embodiment, the portions of the panels 9, 10 and 10 between the side member 3 and the side sill 4 are sandwiched.
11, a means for reducing road noise such as vibration and noise transmitted to the vehicle interior due to vertical vibration input from a suspension device (not shown) and cavity resonance of the tire or a means for reducing wind noise is provided. (1, 1) of local out-of-plane deformation of the panels 9, 10, and 11 at the portion sandwiched between the side member 3 and the side sill 4.
1) The mode natural frequency is lower than the lateral bending resonance frequency (130 to 160 Hz) of the side member, or
The frequency of the wind noise that enters the cabin through the floor panel (7
00 Hz). In this embodiment, the frequency is set to 700 Hz or higher, which is higher than the frequency of wind noise that enters the vehicle interior through the floor panel.

Further, the panels 9, 10, and 11 are shown in FIG.
As shown in the figure, the natural vibration mode shapes 28 of the substantially (1,1) mode are formed.

FIG. 7 shows a region where the sound pressure level of the wind noise applied to the floor panel 6 during running of the vehicle is high, and the noise (wind) is introduced into the vehicle interior through the panels 9, 10, 11, and 14 shown in FIG. Experiments have shown that the low-frequency component of sound enters. However, in the second embodiment, as described in the first embodiment, the panel 14 serves as a means for reducing resonance from 150 to 2 to the vibration input from the center bearing mounting portion 16.
Since the frequency is set in the range of 50 Hz, the panels 9, 10, and the portions between the side members 3 and the side sills 4 are sandwiched.
11 is provided with a means for reducing road noise or a means for reducing wind noise. Therefore, when the noise reduction of the entire floor structure is adjusted, depending on the adjustment, the panel 14 is also provided with a road noise reducing means or a wind noise reducing means so as to reduce the noise transmitted to the vehicle interior. It may be.

FIG. 8 is a graph showing an example of the noise reduction effect of the floor structure of the second embodiment, showing the noise generated by the panel 9 when the vehicle is running. A polygonal line X2 in the graph indicates noise in the conventional floor structure, and a polygonal line Y2 indicates noise in the floor structure to which the present invention is applied. As is apparent from FIG. 8, in the floor structure to which the present invention is applied, the noise at the frequency of the wind noise that enters the vehicle interior through the floor panel when the vehicle is traveling, particularly, is reduced in the low frequency range. I understand.

According to the structure of the second embodiment described above, in addition to the effect of reducing the vibration and noise from the drive system in the first embodiment, the panel of the portion sandwiched between the side member 3 and the side sill 4 is formed. Since the means for reducing the road noise or the means for reducing the wind noise is provided in 9, 10, and 11, the resonance due to the road noise and the wind noise can be reduced, and the vibration and noise transmitted to the occupant in the vehicle compartment can be reduced.

In particular, according to the structure of the second embodiment, the (1,1) mode natural frequency of the local out-of-plane deformation of the panels 9, 10, 11 sandwiched between the side members 3 and the side sills 4 is described. Is set to 700 Hz or higher, which is higher than the frequency of the wind noise that enters the vehicle interior through the floor panel, so that a place where the radiation efficiency is reduced at the resonance frequency due to the wind noise in the corresponding portions 9, 10, and 11 is secured. In addition, vibration and noise can be effectively reduced.

The side member 3 and the side sill 4
Since the panels 9, 10, and 11 sandwiched between are formed in the natural vibration mode shape 28 of substantially (1, 1) mode, a simple structure is required without requiring strict accuracy in panel processing. It is possible to appropriately adjust the natural vibration mode at the corresponding location.

In the second embodiment, the panels 9 and
An example is shown in which the (1,1) mode natural frequency of the local out-of-plane deformation of 10 and 11 is set to 700 Hz or higher, which is higher than the frequency of wind noise that enters the vehicle interior through the floor panel. , 10, 11 of the local out-of-plane deformation (1,
1) The mode natural frequency is set lower than the side-to-side bending resonance frequency (130 to 160 Hz) of the side member to secure a place where the radiation efficiency at the resonance frequency due to road noise is reduced in the corresponding portions 9, 10, and 11. Needless to say, vibration and noise may be effectively reduced.

(Third Embodiment) FIG. 9 shows a floor structure of a third embodiment to which the present invention is applied. This third embodiment is different from the structures of the first and second embodiments described above. In addition, a means for reducing road noise or a means for reducing resonance with respect to vibration input of the rear engine mount mounting portion is provided between the side member 3 at a portion forward of the second cross member 2 and the lower end 5 of the tunnel portion 7. And
Panels 9, 10, 11, 1 that are part of the floor panel
4, Since the vertical walls 18, 19, 20 and the substantially horizontal portions 21, 22, 23 of the tunnel portion 7 are the same as those in the first embodiment, the same portions are denoted by the same reference numerals, and overlapping description is omitted. I do.

In this third embodiment, the panel 12, 13 in front of the second cross member 2 between the side member 3 and the lower end 5 of the tunnel portion 7 has a means for reducing road noise or a rear engine. A resonance reducing means for vibration input of the mount mounting portion 17 is provided,
As means therefor, local out-of-plane deformation of the partial panels 12, 13 in front of the second cross member 2 between the side member 3 and the lower end 5 of the tunnel portion 7 is (1, 1).
1) The mode natural frequency is in a range lower than the left-right bending resonance frequency (130 to 160 Hz) of the side member, or lower than the resonance frequency (600 to 700 Hz) of the rear engine mount mounting portion 17 and in the vicinity. A range (40) higher than the pump noise frequency (250 to 400 Hz) of the transmission oil pump
0 to 600 Hz). In this embodiment, (1, 1) of the local out-of-plane deformation of the portions 12 and 13 is used.
1) The mode natural frequency is set to 110 Hz, which is lower than the left-right bending resonance frequency of the side member.

As shown in FIG. 10, the panels 12 and 13 have flat portions 30 on both left and right edges and these flat portions 30.
Are formed in a natural vibration mode shape 29 of a substantially (1, 3) mode.

FIG. 11 is a graph showing an example of the noise reduction effect of the floor structure of the third embodiment, and shows the noise when a suspension device (not shown) is vibrated.
A polygonal line X3 in the graph indicates noise in the conventional floor structure, and a polygonal line Y3 indicates noise in the floor structure to which the present invention is applied. As is apparent from FIG. 11, in the floor structure to which the present invention is applied, the noise at a frequency at which the floor panel is likely to affect the road noise is reduced over almost the entire area.

According to the structure of the third embodiment described above, in addition to the effects of the first and second embodiments, the distance between the side member 3 and the lower end 5 of the tunnel portion 7 is increased. Panels 12 and 13 in front of second cross member 2
Is provided with means for reducing road noise, so that resonance due to road noise can be reduced, and vibration and noise transmitted to occupants in the passenger compartment can be further reduced.

In particular, according to the third embodiment, the (1,1) mode natural frequency of the local out-of-plane deformation of the panels 12, 13 is set to 110 Hz, which is lower than the lateral bending resonance frequency of the side members. Panels 12 and 13
Thus, it is possible to secure a place where the radiation efficiency is low at a frequency at which the floor panel is likely to affect the road noise, and it is possible to further reduce vibration and noise.

The panels 12 and 13 are provided with flat portions 30 on both right and left side edges, and the gap between these flat portions 30 is substantially (1, 1).
3) Since the mode is formed in the natural vibration mode shape 29, it is possible to appropriately adjust the natural vibration mode at the corresponding location with a simple structure without requiring strict precision in panel processing.

In the third embodiment, the panel 1
The (1,1) mode natural frequency of the local out-of-plane deformation of 2, 13 is lower than the left-right bending resonance frequency of the side member.
Although an example in which the frequency is set to 10 Hz is shown, the (1,1) mode natural frequency of the local out-of-plane deformation of the panels 12 and 13 is determined by the resonance frequency (600 to 70) of the rear engine mount mounting portion.
0 Hz) and the pump noise frequency (25
0 to 400 Hz) (400 to 600H)
It is needless to say that by setting z), a place where the radiation efficiency at the resonance frequency by the rear engine mount mounting portion 17 is reduced in the panels 12 and 13 and vibration and noise can be effectively reduced. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a floor structure of an automobile.

FIG. 2 is an explanatory plan view of a floor structure showing the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a panel shape of each part of the embodiment.

FIG. 4 is a graph showing an example of a noise reduction effect by the floor structure of the embodiment.

FIG. 5 is an explanatory plan view corresponding to FIG. 2 in a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a panel shape according to a second embodiment of the present invention.

FIG. 7 is an explanatory plan view corresponding to FIG. 2, showing a region where the wind sound level applied to the floor panel 6 during running of the vehicle is high.

FIG. 8 is a graph showing an example of a noise reduction effect by the floor structure according to the second embodiment of the present invention.

FIG. 9 is an explanatory plan view corresponding to FIG. 2 in a third embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a panel shape according to a third embodiment of the present invention.

FIG. 11 is a graph showing an example of a noise reduction effect by the floor structure according to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st cross member 2 2nd cross member 3 side member 4 side sill 5 lower end part 6 floor panel 7 tunnel part 8 seat cross member (third cross member) 9, 10, 11, 12, 13, 14 panel 16 center bearing mounting Part 17 Rear engine mount mounting part 18, 19, 20 Vertical wall 21, 22, 23 Substantially horizontal part 24, 29 Substantially (1.1) mode shape 26, 28 Substantially (1.3) mode shape 25, 27, 30 Flat Department

Claims (12)

[Claims] 1. A floor panel having a tunnel portion extending in the vehicle front-rear direction at a substantially central portion in a vehicle width direction; a side member connected to floor panels on both sides of the tunnel portion and extending in the vehicle front-rear direction; It is joined to the approximate center of the vehicle longitudinal direction,
A first cross member extending in the vehicle width direction; and a first cross member joined to a floor panel behind the first cross member,
A second cross member extending in the vehicle width direction, and joined to a floor panel behind the second cross member,
A third cross member extending in the vehicle width direction, a rear engine mount mounting portion provided on a lower surface of a tunnel portion in front of the first cross member, and a center provided on a lower surface of a tunnel portion between the second cross member and the third cross member. A floor structure of an automobile having a bearing mounting portion, wherein a resonance reducing means for vibration input of the rear engine mount mounting portion is provided at a substantially horizontal portion of the tunnel portion and at a portion forward of the second cross members of the vertical walls on both sides. At the same time, resonance reducing means for vibration input of the center bearing mounting portion is provided in a portion sandwiched between the second cross member and the third cross member between both side members including the substantially horizontal portion of the tunnel portion and both side vertical walls. A floor structure of an automobile characterized by the following. 2. As a means for reducing resonance in response to vibration input of the rear engine mount mounting portion, a local out-of-plane deformation of a portion in front of a substantially horizontal portion of a tunnel portion and second cross members of both side vertical walls is provided. ) The mode natural frequency is lower than the resonance frequency of the rear engine mount mounting part, and
It is set higher than the pump noise frequency of the transmission oil pump disposed in the periphery, and as a means for reducing resonance with respect to the vibration input of the center bearing mounting portion, the second cross member of the substantially horizontal portion of the tunnel portion and the vertical walls on both sides. The (1,1) mode natural frequency of the local out-of-plane deformation of the portion sandwiched between the third cross member is set to be equal to or higher than the differential noise frequency of the differential device arranged around, and both sides of the tunnel portion The (1,1) mode natural frequency of the local out-of-plane deformation of the portion sandwiched between the second cross member and the third cross member between the vertical wall and the side member is equal to or higher than the differential noise frequency or the center bearing. The automobile floor structure according to claim 1, wherein the resonance frequency is set lower than a resonance frequency of the mounting portion. 3. The (1,1) mode natural frequency of local out-of-plane deformation of a portion in front of the substantially horizontal portion of the tunnel portion and the second cross members of the vertical walls on both sides is set in a range of 400 to 600 Hz. In addition, the (1,1) mode natural frequency of the local out-of-plane deformation of the portion between the substantially horizontal portion of the tunnel portion and the second cross member and the third cross member of the vertical wall on both sides is 700 Hz. The (1,1) mode specific to the local out-of-plane deformation of the portion set as described above and sandwiched between the second cross member and the third cross member between the vertical walls on both sides of the tunnel and the side members 3. The floor structure of an automobile according to claim 2, wherein the vibration frequency is set to 700 Hz or more or in a range of 150 to 250 Hz. 4. As a means for reducing the resonance of the rear engine mount mounting portion against vibration input, flat portions are provided on the left and right side edges of the substantially horizontal portion of the tunnel portion and the front portions of the second cross members of both side vertical walls, respectively. A space between these flat portions is formed in a substantially (1,1) mode natural vibration mode shape, and as a means for reducing resonance with respect to a vibration input of the center bearing mounting portion, a substantially horizontal portion of the tunnel portion and a vertical wall on both sides are provided. The portions sandwiched between the second cross member and the third cross member are each formed into a substantially (1,1) mode natural vibration mode shape, and the second cross member and the third cross member are provided between the side wall and the side member. A portion sandwiched between the second cross member and the third cross member is provided with flat portions on both left and right side edges, and a space between these flat portions is formed in a substantially (1, 3) mode natural vibration mode shape. Vehicle floor structure according to any one of claims 1 to 3, wherein the door. 5. A road noise or wind noise reducing means is provided in a portion sandwiched between the side member and a side sill which is a skeletal member of a vehicle side portion. The floor structure of the vehicle as described. 6. A (1,1) mode natural vibration of a local out-of-plane deformation of a portion sandwiched between the side member and a side sill which is a skeletal member of a vehicle side portion, as a means for reducing road noise or wind noise. 6. The floor structure of an automobile according to claim 5, wherein the number is set to be lower than a left-right bending resonance frequency of the side member or higher than a frequency of wind noise entering a vehicle interior through a floor panel. . 7. The (1,1) mode natural frequency of local out-of-plane deformation of a portion sandwiched between the side member and a side sill which is a skeletal member of a vehicle side portion is 150 Hz or less, or 600 Hz or more. The automobile floor structure according to claim 6, wherein the vehicle floor structure is set to: 8. As a means for reducing road noise or wind noise, portions sandwiched between the side member and a side sill, which is a frame member on the side of the vehicle, are substantially (1, 1), respectively.
The floor structure of an automobile according to any one of claims 5 to 7, wherein the vehicle is formed in a natural vibration mode shape of 1) mode. 9. A means for reducing road noise or a means for reducing resonance with respect to vibration input of a rear engine mount mounting portion is provided at a portion forward of the second cross member between the side member and both side vertical walls of the tunnel portion. The floor structure of an automobile according to any one of claims 1 to 8, wherein: 10. As a means for reducing road noise or a means for reducing resonance in response to vibration input of a rear engine mount mounting portion, a portion of the front portion of the second cross member between the side member and the vertical wall on both sides of the tunnel portion is provided. The (1,1) mode natural frequency of local out-of-plane deformation is
The range lower than the left and right bending frequency of the side member,
10. The apparatus according to claim 9, wherein the frequency is set to a range lower than a resonance frequency of the rear engine mount mounting portion and higher than a pump noise frequency of a transmission oil pump disposed in the periphery. Car floor structure. 11. The (1,1) mode natural frequency of local out-of-plane deformation of a portion forward of the second cross member between the side member and both side vertical walls of the tunnel portion,
11. The floor structure of an automobile according to claim 10, wherein the frequency is set to 150 Hz or less or a range of 400 to 600 Hz. 12. As a means for reducing road noise or a means for reducing resonance in response to vibration input of a rear engine mount mounting portion, a portion forward of the second cross member between the side member and both side vertical walls of the tunnel portion is provided. The vehicle according to any one of claims 9 to 11, wherein flat portions are provided on both right and left side edges, and a space between these flat portions is formed in a substantially (1, 3) mode natural vibration mode shape. Floor structure.