JPH07228266A - Lower structure of automobile - Google Patents

Abstract

PURPOSE:To reduce the noise physically felt by occupants by efficiently intercepting vibration from a portion where the degree of contribution of noise transmitted to a cabin is high. CONSTITUTION:The lower structure of an automobile comprises a chassis frame P1; and a body P3 containing a cabin forming part P2. An intermediate frame P5 having a given inlet is disposed to at least either the front or the rear of the chassis frame P1 to which a suspension or an engine P4 is attached. The chassis frame P1 and the intermediate frame P5, and the intermediate frame P5 and the body P3 are intercoupled through resilient bodies P6 and P7, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substructure of an automobile for achieving quietness in a vehicle with a frame constructed by supporting a body including a cabin forming portion by a chassis frame.

[0002]

2. Description of the Related Art Conventionally, the lower structure of the above-mentioned automobile is shown in FIG.
As schematically shown in FIG. 3, a chassis frame 61 supports a body 63 including a cabin forming portion 62, and between the chassis frame 61 and the body 63, a cab mount 64 formed of a spring or a rubber mount member.
Is installed.

The above-mentioned chassis frame 61 and body 63 are modeled as shown in FIG. 9 to form a basic model M1 including a chassis frame model 61M and a body model 63M, and a vibration mode is set for this basic model M1. As a result of the actual measurement, the body model 63M on the cabin side resonates at a certain frequency, and a vibration mode as shown by the waveform a in FIG. 9 is obtained, and the chassis frame model 61M resonates at a certain frequency higher than the resonance frequency of the waveform a. A vibration mode such as the waveform b of was obtained.

That is, since the vehicle with a frame shown in FIG. 8 and the basic model M1 shown in FIG. 9 have substantially uniform mass rigidity from the front side to the rear side, the cabin side vibration mode (see waveform a) and the chassis side vibration mode. (Waveform b
However, there is a problem in that noise reduction for passengers in the vehicle compartment cannot be effectively blocked.

In order to solve such a problem, FIG.
As shown in, the chassis frame model 65M in which the front and rear mass rigidity of the chassis frame to which the suspension or the engine is mounted is set to be larger than the mass rigidity of the chassis middle part, and the mass rigidity of the body middle part corresponding to the cabin. And a body model 66M in which a large amount is set with respect to the mass rigidity of the front and rear parts of the body, a model M2 of mass rigidity distribution change type is configured, and the vibration mode is actually measured with respect to this model M2. 1 resonates at a certain frequency, and a vibration mode as shown by the waveform c in FIG. 10 is obtained, and the chassis frame model 65M resonates at a certain frequency higher than the resonance frequency of the waveform c.
A vibration mode having a waveform d of 0 was obtained.

From the comparison between the waveforms a and b in FIG. 9 and the waveforms c and d in FIG. 10, it is difficult to input the vibration in the region where the mass rigidity is large, the amplitude of the vibration mode is suppressed, and the vibration occurs in the region where the mass rigidity is small. It became clear that energy was dissipated.

The mass stiffness distribution change model M2 shown in FIG. 10 and the basic model M1 shown in FIG.
As a result of actually measuring the vibration level α / F for 1000 Hz, the vibration level waveform f of the model M2 can reduce the vibration level as compared with the vibration level waveform e of the model M1 as shown in FIG. There was a problem that it was not possible to achieve sufficient noise reduction for passengers. In addition,
The above-mentioned vibration level α / F can be expressed by the following [Equation 1], and the frequency value on the horizontal axis in FIG. 4 showing the measured data by the model is about 5 times that of the actual vehicle.

[0008]

[Equation 1]

On the other hand, as a lower structure of an automobile configured to double-block the transmission of vibrations to the cabin, there is, for example, the one described in Japanese Patent Laid-Open No. 4-297375. That is, as shown in FIG. 11, the body 7 including the cabin 70.
1, the floor panel 72 and the side sill inner panel 7
3 and a side sill outer panel 74 and a side sill 75 having a closed cross-section structure, while an intermediate frame body 77 is disposed within the closed cross-section of a chassis frame 76, and between the chassis frame 76 and the intermediate frame body 77 described above. The lower mount member 78 is provided on the chassis frame 76, and an opening 79 is formed in the chassis frame 76.
The lower part of the automobile configured to connect the above-mentioned intermediate frame body 77 and the body 71 with the upper mount member 80 using 9 to double-block the vibration transmission to the cabin 70 by these two kinds of mount members 78 and 80. It is a structure.

That is, the transmission of the road surface input from the wheels to the body 71 through the suspension, the chassis frame 76 and the intermediate frame body 77 is double blocked by the above-mentioned two types of mount members 78 and 80. .

However, in this conventional apparatus, the above-mentioned intermediate frame body 77 is disposed between the front and rear suspensions in the closed cross section of the chassis frame 76, and the above-mentioned intermediate frame body 77 is also lowered at the position corresponding to the cabin 70. Due to being connected to the chassis frame 76 via the side mount member 78, the vibration input is transmitted to the entire area of the intermediate frame body 77 in the longitudinal direction, and particularly the vibration transmitted to the intermediate frame body 77 at the cabin corresponding position is transmitted to the cabin 70. Since the noise is transmitted to the front and rear passengers inside, there is a problem that the noise experienced by the passenger cannot be sufficiently reduced.

[0012]

According to a first aspect of the present invention, the chassis frame has a predetermined mass (ma) corresponding to a portion to which the suspension or the engine is attached.
By disposing the intermediate frame having ss) and connecting the intermediate frame and the chassis frame and the intermediate frame and the body with the elastic body, respectively, the upper and lower elastic bodies have a double blocking effect and a mass. With the dynamic damper function of the intermediate frame, it is possible to effectively block the vibration from the part that contributes significantly to the noise transmitted to the cabin (cabin), and to sufficiently reduce the noise experienced by the occupants. The purpose is to provide an automobile substructure that enables

According to a second aspect of the present invention, in addition to the object of the first aspect of the invention, on the chassis frame side, the mass or rigidity of the intermediate frame disposing portion is set to be large with respect to other portions. However, by setting the mass or rigidity of the intermediate frame installation area to be small on the body side and the mass or rigidity of the cabin corresponding part to be large, vibration input to the chassis frame side where the suspension or engine is mounted is input. An object of the present invention is to provide a substructure of an automobile which can further improve quietness by making the vibration mode amplitude suppressed in the cabin corresponding portion.

According to a third aspect of the present invention, in addition to the object of the first or second aspect of the invention, the elastic coefficients of the upper and lower elastic bodies that connect the chassis frame and the intermediate frame are made different from each other. Therefore, it is an object of the present invention to provide a substructure of an automobile capable of obtaining a good vibration isolation effect in a wide frequency band by making the resonance peaks of both upper and lower elastic bodies different while avoiding the floating state of the body.

[0015]

The invention according to claim 1 of the present invention is a substructure of an automobile in a frame-equipped vehicle including a chassis frame and a body including a cabin forming portion, wherein a suspension or an engine is provided. At least one of a front portion and a rear portion of the chassis frame to be attached is provided with an intermediate frame having a predetermined mass, and between the chassis frame and the intermediate frame,
Further, it is characterized in that it is a lower structure of an automobile in which the intermediate frame and the body are connected by elastic bodies.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the chassis frame side has the mass or rigidity of the portion where the intermediate frame is disposed in the chassis intermediate portion. On the other hand, while being set to a large value, the body side is a substructure of an automobile in which the mass or rigidity of the portion where the intermediate frame is arranged is set to be smaller than the intermediate portion of the body.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, the elastic coefficient of the lower elastic body connecting the chassis frame and the intermediate frame, It is characterized in that it is a lower structure of an automobile in which elastic coefficients of upper elastic bodies connecting the intermediate frame and the body are different from each other.

[0018]

According to the invention described in claim 1 of the present invention, as shown in the claim correspondence diagram of FIG. 5, with a frame provided with the chassis frame P1 and the body P3 including the cabin forming portion P2. In a car, a chassis frame P to which a suspension or engine P4 is attached
An intermediate frame P5 having a predetermined mass (mass) is provided on at least one of the front part and the rear part of 1, and the above-mentioned chassis frame P1 and intermediate frame P are provided.
5, and the intermediate frame P5 and the body P3 are connected by elastic bodies P6 and P7, respectively.

Since the vibration transmission is doubly blocked by the elastic members P7 and P6 above and below the intermediate frame P5, the vibration transmitted to the cabin forming portion P2 can be reduced. Moreover, the intermediate frame P5 having the above-mentioned mass has a dynamic damper function. That is, when the chassis frame P1 as the vibrating member resonates due to the road surface input,
The above-described intermediate frame P5 (mass) resonates in the opposite direction to this resonance frequency and absorbs the vibration transmitted to the cabin side. Therefore, due to the synergistic action of this dynamic damper function and the above-mentioned double interruption effect. The vibrations can be efficiently blocked, the noise experienced by the passenger in the cabin can be sufficiently reduced, and quietness can be ensured.

According to the second aspect of the present invention,
In addition to the effect of the invention described in claim 1, since the mass or the rigidity or the distribution of the both is set as described above, since the mass or the rigidity is large on the chassis frame side to which the suspension or the engine is mounted, the vibration input is applied. In addition to being difficult, the mass or rigidity of the body intermediate part as the cabin forming part on the body side is also large,
The amplitude of the vibration mode can be suppressed, and as a result, quietness can be further improved.

According to the invention of claim 3 of the present invention,
In addition to the effect of the invention described in claim 1 or 2, the elastic coefficient of the lower elastic body and the elastic coefficient of the upper elastic body are made different from each other. There is an effect that the resonance peaks of both elastic bodies can be made different from each other to achieve a good vibration isolation effect in a wide frequency band.

Incidentally, when the elastic coefficients of the upper and lower elastic bodies are both small, a floating state of the body occurs, the body floats up from the chassis frame, and when the elastic coefficients of the upper and lower elastic bodies are the same. Not only the vibration is increased at the time of resonance, but also the vibration isolation effect in a wide frequency band cannot be obtained, but such a problem can be solved by the above configuration.

Further, the content of the invention according to claim 3 is shown in FIG.
This will be described in detail with reference to the correspondence diagram shown in FIG. 7. The center of gravity is now G,
G1, G2, G3, the mass of the chassis frame is M,
The mass of the intermediate frame is m, the mass of the cabin is Ma, the centrifugal force at the time of turning is F, and the elastic coefficient (spring constant) of each elastic body is k.
1. k2 (however, k1> K2) and the spring constant k
Considering that the objects connected by the elastic body 1 have a behavior similar to that of an integrated body, the roll angle due to the centrifugal force of the cabin in the configuration of FIG. 6 and the configuration of FIG. In the configuration of 7, the intermediate frame mass m is added to the cabin mass Ma, and the mass (Ma + m)
The spring constant of the mount that supports the load applied to
Since it is 2, the size becomes large as compared with the configuration of FIG.

Therefore, in the configuration of FIG. 6 and the configuration of FIG. 7, the occupant in the cabin receives a greater sense of security from the vehicle when turning, because the configuration of FIG.

Further, the fact that the heavy object on the spring moves means that one wheel is heavily loaded, and it is ideal that the left and right wheels are evenly loaded. The turning speed limit will be lowered.

As described above, the maneuverability in terms of sensation and the maneuverability in terms of vehicle motility can be made excellent.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The drawing schematically shows the lower structure of an automobile in a vehicle with a frame. In FIG. 1, a chassis frame 1 supports a body 3 including a cabin forming portion 2 in the vehicle with a frame.

The above-mentioned chassis frame 1 includes a frame front portion 1a on which the engine 4 and the front suspension device are mounted, and a frame intermediate portion 1b corresponding to the cabin.
And a frame rear portion 1c to which the rear suspension device is attached are integrally formed.

Then, in the chassis frame 1 described above, the intermediate frames 5 and 5 having a predetermined mass (mass) and rigidity are arranged only corresponding to the frame front portion 1a and the frame rear portion 1c to which the suspension device or the engine 4 is attached. The lower elastic bodies 6, 6 are provided between the intermediate frames 5, 5 and the frame front portion 1a and the frame rear portion 1c, and the upper elastic bodies 7, 7 are provided between the intermediate frames 5, 5 and the body 3. Are connected with each other.

Here, each of the elastic bodies 6 and 7 is specifically composed of a spring or a rubber mount member, and the elastic coefficient of the lower elastic body 6 (when the lower elastic body is composed of a spring). The spring constant) and the elastic coefficient of the upper elastic body 7 are different from each other.

Moreover, in the chassis frame 1 described above, the mass rigidity of the frame front portion 1a and the frame rear portion 1c in which the above-mentioned intermediate frames 5 and 5 are arranged (specifically, the mass rigidity and / or the rigidity, both of which are hereinafter referred to simply as the mass rigidity). Is set to be larger than the mass rigidity of the frame intermediate portion 1b. Specifically, in order to increase the rigidity, the closed cross section forming the chassis frame 1 is increased, and in order to increase the mass, the plate thickness of the plate material forming the closed cross section is increased, or a component forming the vehicle. Should be supported rigidly.

In addition, in the body 3 described above, the mass rigidity of the front and rear portions of the body in which the intermediate frames 5 and 5 are arranged is set to be smaller than the mass rigidity of the intermediate portion of the body corresponding to the cabin forming portion 2. There is. In other words, the mass rigidity of the middle part of the body is set to be larger than the mass rigidity of the front and rear parts of the body.

In order to compare the vibration level of the actual vehicle having the above structure with that of the conventional structure, as shown in FIG. 4, the mass rigidity distribution with the intermediate frame including the chassis frame model 1M, the intermediate frame model 5M and the body model 3M is changed. As a result of actually measuring the vibration level α / F at a frequency of 10 to 1000 Hz by constructing the model M3 of the shape, it is possible to obtain a sufficient noise reduction effect in the cabin in a wide frequency band as shown by the vibration level waveform g in the figure. I was able to.

That is, since the vibration transmission is doubled by the upper and lower elastic bodies 7 and 6 of the intermediate frame 5, the vibration transmitted to the cabin forming portion 2 can be reduced.
Moreover, the intermediate frame 5.5 having the above-mentioned mass has a dynamic damper function. In other words, when the chassis frame 1 as the vibrating member resonates due to the road surface input through the road surface, the wheels, and the suspension device, the intermediate frames 5 and 5 perform the opposite resonance with respect to this resonance frequency, and the cabin Since the vibration transmitted to the side is absorbed, the vibration is efficiently cut off and damped by the synergistic effect of the dynamic damper function and the double cutoff effect described above.
There is an effect that the noise felt by the occupant in the cabin is sufficiently reduced and the quietness is secured.

In addition, since the mass rigidity distribution is set as described above, the frame front portion 1a and the frame rear portion 1c of the chassis frame 1 to which the suspension device (specifically, the front suspension device and the rear suspension device) or the engine is mounted are Since the mass rigidity is large,
The above-mentioned vibration input becomes difficult to enter and the mass rigidity of the body intermediate portion as the cabin forming portion 2 on the body 3 side is also large, so that the amplitude of the vibration mode can be suppressed,
As a result, there is an effect that the quietness can be further improved.

Furthermore, since the elastic coefficient of the lower elastic body 6 and the elastic coefficient of the upper elastic body 7 are different from each other, the floating state of the upper and lower elastic bodies 7, while avoiding the floating state of the body 3, Since the resonance peaks of the upper and lower elastic bodies 7 and 6 can be made different from each other due to the difference in each elastic coefficient in 6, the excellent vibration isolation effect can be exhibited in a wide frequency band.

FIG. 2 shows another embodiment of the lower structure of the automobile. In the embodiment of FIG. 2, the structure is a frame-in-frame structure. That is, the closed cross section of the frame front portion 1a and the frame rear portion 1c in the above-described chassis frame 1 having the closed cross section configuration and the plate thickness of the plate material forming the closed cross section are both set to be large, and the frame front portion 1a and the frame are formed. The above-mentioned intermediate frames 5 and 5 are arranged in the closed cross section of the rear portion 1c. Here, the above-mentioned intermediate frame 5 is mainly of a closed cross-section structure, but in order to improve the dynamic damper function, it is made thicker or has a solid cross-section structure.

Corresponding to the above-mentioned upper elastic body 7, openings 8 and 8 are formed on the top deck surfaces of the frame front portion 1a and the frame rear portion 1c, and the above-mentioned upper elastic portions 8 and 8 are utilized. The body 7 is attached. The other conditions are the same as in the previous embodiment.

Even with this structure, the same operation and effect as those of the previous embodiment can be obtained. Therefore, in FIG. 2, the same parts as those in FIG. FIG. 3 shows still another embodiment of the lower structure of the automobile. In the embodiment of FIG. 3, the structure is a ladder-in-ladder frame structure. That is, the cross-shaped chassis frame 1 is provided, and the chassis frame 1
At the front suspension device, the rear suspension device or the frame front part 1a to which the engine 4 is mounted, and the frame rear part 1c, between the left and right frame members, there are arranged intermediate frames 5, 5 having a closed cross-section structure in the shape of a rectangular frame in plan view. , These intermediate frames 5 and 5 and the frame front part 1
a and the frame rear portion 1c are connected by a plurality of shear-type rubber mount members 6a corresponding to the lower elastic body 6, and the top deck surfaces of the intermediate frames 5 and 5 and the lower surface of the body 3 are connected to the upper elastic body described above. 7 are connected by a plurality of compression type rubber mount members 7a having a small elastic coefficient corresponding to 7, and the top deck surface of the frame front portion 1a and the frame rear portion 1c and the body 3 are connected.
The lower surface and a plurality of compression type rubber mount members 9 having a large elastic coefficient
It is connected with. The other conditions are the same as in the previous embodiment.

Even with this construction, the same operation and effect as those of the previous embodiment can be obtained. Therefore, in FIG. 3, the same parts as those in the previous figure are designated by the same reference numerals and symbols, and detailed description thereof will be given. Is omitted.

In the correspondence between the structure of the present invention and the above-described embodiment, the front portion of the chassis frame of the present invention corresponds to the frame front portion 1a of the embodiment, and the same applies to the rear portion of the chassis frame. The chassis middle part corresponds to the frame middle part 1b, and the lower elastic body corresponds to the rear part 1c and the lower elastic body 6 and the shear rubber mount member 6a.
The upper elastic body corresponds to the upper elastic body 7 and the compression type rubber mount member 7a, but the present invention is not limited to the configurations of the above-described embodiments.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a lower structure of an automobile of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the lower structure of the automobile of the present invention.

FIG. 3 is an explanatory view showing still another embodiment of the lower structure of the automobile of the present invention.

FIG. 4 is a characteristic diagram showing a change in vibration level with respect to frequency.

FIG. 5 is a complaint correspondence diagram.

FIG. 6 is an explanatory diagram of claim 3;

FIG. 7 is an explanatory diagram of claim 3;

FIG. 8 is an explanatory view showing a lower structure of a conventional automobile.

FIG. 9 is an explanatory view showing a conventional basic model and its vibration mode.

FIG. 10 is an explanatory diagram showing a conventional mass rigidity distribution change model and its vibration mode.

FIG. 11 is a cross-sectional view showing a lower structure of a conventional vehicle having a double blocking structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Chassis frame 1a ... Frame front part 1b ... Frame middle part 1c ... Frame rear part 2 ... Cabin formation part 3 ... Body 4 ... Engine 5 ... Intermediate frame 6 ... Lower elastic body 6a ... Shear type rubber mount member 7 ... Upper elasticity Body 7a ... Compression type rubber mount member

Front page continued (72) Inventor Shigenori Ishida 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (3)

[Claims] 1. A lower structure of an automobile in a vehicle with a frame including a chassis frame and a body including a cabin forming portion, wherein at least one of a front portion and a rear portion of a chassis frame on which a suspension or an engine is mounted. , An intermediate frame having a predetermined mass is provided, and between the chassis frame and the intermediate frame,
In addition, a lower structure of an automobile in which the intermediate frame and the body are connected by elastic bodies. 2. The chassis frame side sets the mass or rigidity of the portion where the intermediate frame is arranged to be large relative to the chassis intermediate portion, while the body side is the portion where the intermediate frame is arranged. The undercar structure of an automobile according to claim 1, wherein the mass or rigidity is set to be small with respect to the middle part of the body. 3. The elastic coefficient of a lower elastic body that connects the chassis frame and the intermediate frame and the elastic coefficient of an upper elastic body that connects the intermediate frame and the body are different from each other. The substructure of the automobile according to 1 or 2.