JPS6251190B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mount structure for attaching the body of a bonnet-type truck to a body frame, and more particularly to a cab mount structure for attaching the body of a bonnet-type truck to the frame at three locations: the front of the vehicle body and the front and rear portions of the cabin floor. It is about improvement.

In automobiles, in order to improve ride comfort and noise inside the vehicle, it is desirable to use mount rubber with particularly high vibration absorption ability for the mounts around the cabin in order to prevent vibrations from the vehicle body frame from being transmitted to the cabin as much as possible. Previously, compression type mount rubber was used to mount this part (Japanese Utility Model Publication No. 56-39374), or shear type mount rubber was used (Utility Model Publication No. 46-29289).
However, all of them have advantages and disadvantages and are not fully satisfactory.

In other words, compression type mount rubber is strong against vibrations in the front, back, left, and right directions, but does not have sufficient absorption capacity for vibrations in the vertical direction, making it impossible to sufficiently absorb vibrations.Therefore, it is difficult to reduce interior noise to a satisfactory level. I can't. On the other hand, shear type mount rubber absorbs vibrations in the vertical direction well, but
It has the disadvantage that it is weak in the horizontal direction and cannot sufficiently control the amplitude of vibrations at low frequencies in the vertical direction as well. Therefore, if a shear type mount rubber is used, the support of the cabin becomes unstable, and although the noise inside the car is reduced, the cabin becomes unsteady and the ride becomes uncomfortable. Furthermore, interference may occur between the cabin and the box, which may even cause problems.

In view of the above circumstances, the present invention effectively reduces the transmission of vibration from the vehicle body frame to the cabin, significantly reduces the level of noise inside the vehicle, improves riding comfort, and further eliminates the wobbling of the cabin. The object of the present invention is to provide a cab mount structure for a bonnet type truck that achieves stable riding comfort.

The cab mount structure of the present invention is characterized in that a compression type mount rubber is used for the mount device that attaches the front part of the cabin floor to the body frame, and a shear type mount rubber is used for the mount device that attaches the front and rear parts of the cabin floor to the body frame. That is.

In other words, shear-type mounts with high vibration isolation are used for the front and rear cabin mounts, which have a high contribution rate to cabin noise and ride comfort, while shear type mounts with high vibration isolation are used at the front of the car body, which has a relatively low contribution rate, and are inexpensive and can control vibration. A highly effective compression type mount is used to reduce adverse effects such as wobbling caused by excessive relative displacement between the vehicle body frame and the cabin.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a side view showing an example of a bonnet type truck, FIG. 2 is a plan view thereof, and FIG. 3 is a perspective view showing only its frame. The body of this type of truck has a bonnet section 1 and a cabin section 2 at the front.
There is a box 3 next to it. These are mounted on the vehicle body frame 4, including a first mount 5A (front cab mount) at the front of the vehicle body, a second mount 5B (intermediate cab mount) at the front of the cabin floor, and a third mount 5 at the rear of the cabin floor.
The front portion is attached via C (rear cab mount), and the box 3 is attached via another rear mount (not shown).

The effect of these mounts on vibration absorption differs somewhat depending on their position, and by using the appropriate type of mount rubber depending on the mount position, it is possible to effectively reduce interior noise and improve ride comfort. Ru.

Figures 4A, 4B, and 4C are graphs showing the results of measuring the sound pressure (dB/Kg) inside the cabin by changing the vibration frequency (Hz) when vibration is applied to the frame side of the cab mount. FIG. 4B shows the measurement results for the first mount 5A, FIG. 4B shows the measurement results for the second mount 5B, and FIG. 4C shows the measurement results for the third mount 5C. In each graph, the solid line shows the measurement results when a shear type mount rubber is used, and the broken line shows the measurement results when a compression type mount rubber is used.

As can be seen from these measurement results, when changing the cab mount from the compression type (dashed line) to the shear type (solid line), the degree of reduction in cabin noise is greatest for the second mount 5B (Figure 4B), followed by the second mount 5B (Fig. 4B). The third mount 5C (FIG. 4C) is larger, and the first mount 5A (FIG. 4A) shows almost no difference. Quantitatively, there is almost no difference in the first mount in the above measurement, and 300Hz in the second mount.
There is a difference of about 20dB/Kg in the third mount, and about 10dB/Kg in the third mount.

Furthermore, Fig. 5 shows the results of measuring the longitudinal vibration of the cabin floor on a public road. Figure 5 shows the frequency (Hz) on the horizontal axis and the vibration power spectrum density (PSD) (g ² /Hz) on the vertical axis, and the solid line indicates that the first to third mounts are all shear type mount rubber. In this case, the broken line indicates the case where all mounts are made of compression type mount rubber. According to this, it can be seen that the shear type suppresses vibration to about 1/100 of the compression type at 20-50Hz.

From these measurement results, it can be seen that the shear type mount rubber has a large vibration absorption effect, especially at the second and third mount positions. However, if these shear type mount rubbers are installed at these two locations, the relative displacement between the vehicle body frame and the vehicle body in the vertical, longitudinal, and horizontal directions will increase, causing the cabin to feel unsteady, and the difference between cabin 2 and box 3 to increase. A problem arises in that interference may occur. Therefore, in the present invention, the compression tine mount rubber, which is inexpensive and has a large vibration control effect, is used for the first mount, which has the least effect on vibration transmission, to improve riding comfort and to have a large overall vibration absorption effect. This is a cab mount that effectively suppresses interior noise.

Next, each type of mounting device will be explained in detail with reference to the drawings.

FIG. 6 shows a compression type mounting device. This is commonly called a skewer type, and an elastic body 12 having a through hole 12A in the center is sandwiched between the cabin floor 10 and the body frame 11, and the body frame 11 is further sandwiched between the body frame 11 and the opposite side of this elastic body 12. Another elastic body 13 having a through hole 13A in the center is provided, and these two elastic bodies 12 and 13, the cabin floor 10 (consisting of two materials in the figure), and the vehicle body frame 11 are vertically connected with washers 1.
4 and 15, and are tightened with bolts 16 and nuts 17. Relative displacement (vibration) in the vertical direction between the cabin and the frame is buffered by compressive deformation of the elastic bodies 12 and 13 in the axial direction of the bolt 16,
Absorbed. Further, the relative displacement in the horizontal direction is buffered and absorbed by the bolt 16 being displaced back and forth and left and right inside the relatively large opening 11A of the frame 11, and the elastic bodies 12 and 13 being deformed.

FIG. 7 shows a shear type mounting device.
This has a shear type elastic body 22 interposed between the cabin floor 20 and the vehicle body frame 21. An outer rubber retaining ring 23 is fixed to the upper surface of the frame 21 under an upper bracket 20A fixed to the lower surface of the cabin floor 20. An annular elastic body 22 with a plate 22A embedded therein is fixedly fixed in the ring 23, and an inner rubber retaining ring 24 extends upward from the inner surface of the elastic body 22. Opening 21 provided in 21
A lower bracket 26 with a rebound stopper elastic body 25 fixed on its upper surface, which extends downward and outward from A, is attached to the upper bracket 20A together with the inner rubber retaining ring 24 by a pair of nuts 27A, 2.
7B and a stand 28.

The plate 22A embedded in the annular elastic body 22 is made of a material with high rigidity, such as steel, and has the effect of increasing the spring constant against lateral vibration. That is, when the vibration increases in the lateral direction, the spring constant acts as a stopper and gradually increases the spring constant.

In addition, there is a slight gap 2 above and below the annular elastic body 22.
2a and 22b are formed so that the deformation of the shear type elastic body becomes a compression type when the vertical vibration becomes large to a certain extent. As a result, the spring constant of this mount rubber increases in the vertical direction as well. At this time as well, the change is not sudden but gradual, resulting in a smooth increase in the spring constant.

As a result, when the amplitude is small, vibrations in both the vertical and horizontal directions are gently absorbed using a small spring constant, and as the amplitude increases, the spring constant is increased to provide stable elastic support. It is possible to mount the vehicle with good ride comfort and noise reduction inside the vehicle.

During rebound, the rebound stopper elastic body 25 comes into contact with the lower surface of the vehicle body frame 21 and acts as a soft stopper, thereby regulating the amplitude of vertical vibration.

The compression type and shear type mount rubbers as described above are mounted on the first mount 5A at the front of the vehicle body and the second mount 5A at the front of the cabin floor, respectively.
B, and the third mount 5 at the rear of the cabin floor.
By selectively using C as described above, it is possible to improve riding comfort and effectively reduce interior noise, thereby realizing a quiet bonnet-type truck with less vibration.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a bonnet type truck employing the cab mount structure of the present invention;
Figure 2 is a plan view, Figure 3 is a perspective view showing only the body frame, and Figure 4A is a graph showing the relationship between the frequency of vibrations applied to the body frame and the sound pressure generated in the cabin. Figure 4B shows a comparison of the mounts at the front of the cabin floor, Figure 4C shows a comparison of the mounts at the rear of the cabin floor, and Figure 5 shows a comparison of the mounts at the front of the cabin floor. A graph showing the results of measuring longitudinal vibration, FIG. 6 is a sectional view showing a compression type mount rubber used in the cab mount structure of the present invention, and FIG. 7 is a sectional view showing a shear type mount rubber. 1...Bonnet, 2...Cabin, 3...Box, 4...Vehicle frame, 5A...Vehicle front mount (first mount), 5B...Cabin floor front mount (second mount), 5C... Cabin floor rear mount (third mount), 1
0,20...cabin floor, 11,21...body frame, 12,13...elastic body, 22...annular elastic body, 22A...buried plate, 23...outer rubber retaining ring, 24...inner rubber retaining Ring, 25...Elastic body for rebound stopper.

Claims (1)

[Scope of Claims] 1. An automobile cab mount structure in which the front part of the vehicle body and the front and rear parts of the cabin floor of a bonnet-type truck are respectively attached to the vehicle body frame via mounting devices, wherein A compression type mount rubber that is compressively deformed in response to vertical vibration is used, and a shear type mount rubber that is sheared and deformed in response to the vertical vibration of the vehicle body is used for the front and rear mounting devices of the cabin floor. Car cab mount structure.