JPH0534244Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a dynamic damper for a rear suspension member, particularly for a rear suspension member that supports a trailing arm in a trailing arm type suspension of an automobile. Concerning suitable dynamic dampers.

(Prior art) A rear suspension member for a trailing arm has a case for a differential gear in the center, a cushion and a bracket at each end, and a bolt that passes through the cushion and is screwed into the bolt. The trailing arm is attached to the vehicle body by a nut, and the trailing arm is swingably supported by a bracket. The rear wheel attached to the trailing arm is rotated by receiving power from a differential gear device housed in the case via a drive shaft.

When an automobile is running, the meshing vibration of the differential gear is applied to the rear suspension member, causing abnormal noise. Therefore, a dynamic damper is sometimes attached to the rear suspension member to reduce the vibration.

As shown in FIG. 5, the conventional dynamic damper 10 consists of a rubber material 11 and a mass material 12. The rubber material 11 is fixed to a bracket 14 attached to a rear suspension member 13, and It is constructed by fixing a mass material 12 to the upper side.

(Problem to be solved by the invention) The inventors of the present invention repeatedly conducted vibration experiments, and found that the vibrations applied to the rear suspension member 13 due to the meshing of the differential gear device are caused by vertical bending vibration and front-rear bending vibration. It was confirmed that the frequency of the front and back bending vibrations generally appears higher than the frequency of the top and bottom bending vibrations.

By the way, in a dynamic damper including a rubber material, it is known that the resonance frequency for vibrations in the shear direction of the rubber material is lower than the resonance frequency for vibrations in the compression direction.

Considering these two facts, it can be said that conventional dynamic dampers are not effective against vertical and longitudinal bending vibrations. This is because if the spring constant of the rubber material 11 is selected so as to resonate with the front and rear bending vibrations, the frequency of the vertical bending vibrations that actually appears lower than this,
The resonant frequency of the rubber material 11 in the compression direction increases. Conversely, if the spring constant of the rubber material 11 is selected so as to resonate with vertical bending vibrations, the resonance frequency of the rubber material 11 in the compression direction increases. This is because the resonance frequency in the shear direction becomes smaller.

Therefore, in order to effectively deal with vertical and longitudinal bending vibrations using the conventional dynamic damper 10, it is necessary to select a spring constant in the compression direction so as to resonate with the vertical bending vibrations, and It is necessary to provide a special spring constant with a spring constant in the shear direction so as to resonate with the bending vibration, which is disadvantageous in terms of cost and weight.

An object of the present invention is to provide a dynamic damper for a rear suspension member that can cope with vertical and longitudinal bending vibrations using a single dynamic damper.

(Means for Solving the Problem) The present invention is a dynamic damper that is provided on a rear suspension member extending in the lateral direction of the vehicle body, and includes a mounting end and a free damper spaced apart from the mounting end in the longitudinal direction of the vehicle body. a substantially straight rubber member having an end and attached to the rear suspension member at the mounting end, and a mass secured to the free end of the rubber member, the mass and the The rubber material is arranged such that the mass material is located in front or behind the rubber material, and the longitudinal bending vibration applied to the rear suspension member is controlled by the spring constant in the compression direction of the rubber material. The vertical bending vibration applied to the member is caused to resonate with the spring constant of the rubber material in the shear direction.

(Function and Effect) In order to cause the large frequency longitudinal bending vibration to resonate with the spring constant of the rubber material in the compression direction, and the small frequency vertical bending vibration to resonate with the rubber material's spring constant in the shear direction, it is necessary to This is possible by appropriately selecting the shape and composition of the materials.

As the rubber material is substantially straight and is attached to the rear suspension member at the mounting end and extends in the longitudinal direction of the vehicle body, vibrations in the compression direction applied to the rubber material cause deformation in the compression direction and deformation in the shear direction. There is substantially no occurrence of deformation in the shear direction and deformation in the compression direction due to vibration in the shear direction. Therefore, when selecting a rubber material, consider only the spring constant of the rubber material in the compression direction for the longitudinal bending vibration applied to the rear suspension member, and only the spring constant of the rubber material in the shear direction for the vertical bending vibration. is sufficient, and it is easy to manufacture a dynamic damper. The spring constant in the compression direction of the dynamic damper manufactured in this way resonates the longitudinal bending vibration of the rear suspension member, and the spring constant in the shear direction resonates the vertical bending vibration of the rear suspension member. A dynamic damper can deal with longitudinal and vertical bending vibrations, reducing cost and weight.

Since the dynamic damper reduces the amplitude of vibration, it is possible to suppress the generation of abnormal noise caused by the meshing vibration of the differential gear, and to reduce the discomfort experienced by the occupants.

(Example) The dynamic damper 20 is shown in FIGS. 1 and 2.
As shown in the figure, it is provided in a rear suspension member 22 disposed in the lateral direction of the vehicle body, and is configured to resonate with longitudinal bending vibrations and vertical bending vibrations applied thereto.

The rear suspension member 22 has a case 24 for a differential gear in the center, and brackets 28 for supporting a cushion 26 and a trailing arm at each end. The rear suspension member 22 is coupled to the vehicle body by a bolt passing through the cushion 26 and a nut screwed into the bolt. A trailing arm is coupled to the bracket 28, and the wheels mounted on the trailing arm receive power from a differential gear device disposed within the case 24 via a drive shaft and are rotated. The above structure is known per se and has no direct relation to the present invention, so illustrations and detailed explanations will be omitted.

The dynamic damper 20 has a mounting end 31a,
A substantially straight rubber member 30 having a free end 31b spaced apart from the mounting end 31a in the longitudinal direction of the vehicle body and attached to the rear suspension member 22 at the mounting end 31a; and a free end of the rubber member 30. 31
and a mass material 32 fixed to b. Mass material 32
and the rubber material 30 are arranged such that the mass material 32 is located in front or behind the rubber material 30.

In the illustrated embodiment, the attachment end 31a of the rubber material 30
A mounting plate 34 exhibiting a T-shape is attached to the free end 3.
A mass material 32 is adhered to each of the parts 1b. On the other hand, the front surface 23a of the rear suspension member 22
A bracket 36 is welded to each end portion of the bracket 36 and projects forward. Horizontal side 35a of mounting plate 34 and horizontal side 3 of bracket 36
7a and two bolts 38, and nuts 40.
By screwing in, both horizontal sides are joined. As a result, the mass material 32 is positioned forward from the rubber material 30.

The spring constant of the rubber material 30 in the compression direction, that is, the longitudinal direction A, is determined by the frequency of the longitudinal bending vibration applied to the dynamic damper 20, and the spring constant of the rubber material 30 in the shear direction, that is, the vertical direction B, is determined by the dynamic damper 20. The mass (weight) of the mass material is adjusted so that it resonates with the frequency of the applied vertical bending vibration.
Determined by taking into account.

In the illustrated embodiment, the pair of brackets 36 are
The dynamic dampers 20 are located at both ends of the rear suspension member 22 near the cushion 26, and therefore each dynamic damper 20 is provided near the cushion. Since the amplitude of the meshing vibration of the differential gear is greatest at the center of the rear suspension member 22 and smaller at both ends, the weight of the mass 32 of the dynamic damper 20 can be reduced in accordance with the illustrated embodiment. Moreover, since each dynamic damper 20 has a resonance frequency in the longitudinal direction and the vertical direction, it is sufficient to arrange one dynamic damper at each end, whereas the conventional dynamic damper 10 cannot cope with this problem. , the weight can be significantly reduced compared to having to provide two for each end, one for front and rear and one for upper and lower.

For example, it is conceivable that by providing two conventional dynamic dampers 10 at the center of the rear suspension member 22, it is possible to cope with the longitudinal and vertical bending vibrations applied to the rear suspension member 22. If this is done, the number will be the same as in the illustrated embodiment. However, the center of the rear suspension member 22 is a place where interference with the vehicle body, propeller shaft, etc. is likely to occur.
In practice, it is difficult to arrange two dynamic dampers. Even if two dynamic dampers 10 could be arranged, the amplitude of the vibration at the center of the rear suspension member 22 is large, so the weight of the mass material would have to be increased. No such disadvantage will arise.

In addition, in the above embodiment, the dynamic damper 2
0 rubber material 30 is the rear suspension member 22
The mass material 32 is fixed to the front surface of the main body. Alternatively, the rubber material 30 may be attached toward the rear from the rear suspension member 22, and the mass material 32 may be attached to the rubber material 30 so as to be at the rear of the rubber material 30.

FIG. 3 shows the results of measuring sound pressure levels for the conventional dynamic damper C shown in FIG. 5 and the dynamic damper D according to the present invention by changing the meshing frequency of the differential gear device. Further, FIG. 4 shows the results of changes in sound pressure level with respect to changes in 1/3 octave center frequency for conventional example C and present invention D. It can be seen that the sound pressure level of the dynamic damper D according to the present invention is lower than that of the conventional damper C over the entire frequency range.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the dynamic damper according to the present invention taken along line 1-1 in FIG. 2, FIG. 2 is a perspective view of the rear suspension member, and FIGS. The figure is a graph showing the relationship between the meshing frequency and the sound pressure level of a differential gear device, and FIG. 5 is a sectional view of a conventional dynamic damper. 20...Dynamic damper, 22...Rear suspension member, 30...Rubber material, 32...
Mass material, 34...Mounting plate, 36...Bracket.

Claims (1)

[Scope of utility model registration request] A dynamic damper provided on a rear suspension member extending in the lateral direction of a vehicle body, the dynamic damper having a mounting end and a free end spaced apart from the mounting end in the longitudinal direction of the vehicle body, wherein the rear suspension member is connected to the rear suspension member at the mounting end. a substantially straight rubber member attached to the rubber member; and a mass member secured to the free end of the rubber member, the mass member and the rubber member being arranged such that the mass member is located in front of the rubber member or The longitudinal bending vibration applied to the rear suspension member is controlled by a spring constant in the compression direction of the rubber material, and the vertical bending vibration applied to the rear suspension member is controlled by a spring constant in the shear direction of the rubber material. A dynamic damper for the rear suspension member that resonates with a spring constant of .