JPH0516005Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a suspension device for a vehicle.
In particular, the present invention relates to vibration suppression technology using resonance of unsprung members.

(Prior Art) As a conventional suspension device, a four-link + lateral rod type suspension, which is used as a rear suspension of a rear wheel drive vehicle, as shown in FIG. 5, for example, is known.

(Source: “New Automotive Engineering Handbook <Part 5>” 4)
(See Figure 4-8 on page 5 of Chapter) This conventional 4-link + lateral rod suspension consists of a rear axle case 01 into which the drive shaft is inserted, and a rear axle case 01 that has a drive shaft inserted therein.
Suspension members (upper links 02, 02, lower links 03, 03, lateral rods 04, coil springs 05, 05, shock absorber 0
6,06).

Incidentally, rubber bushings are interposed between the upper links 02, 02, the lower links 03, 03, and the lateral rods 04, and the case side support portions and the vehicle body side support portions, and the vehicle body side support portions of the coil springs 05, 05 are provided with rubber bushings. A seat is interposed, and a mounting insulator is interposed on the vehicle body side support portion of the shock absorbers 06, 06.

Therefore, unsprung vibrations due to vibration input from the engine, road surface, etc. that are transmitted from the rear axle case 01 to the vehicle body via the suspension members are damped by elastic members such as rubber bushes, rubber sheets, and mounting insulators. It was something like that.

(Problem to be solved by the invention) However, in such conventional suspension devices, there was no means to suppress the resonance of the rear axle case, which is an unsprung member, so the rear axle case If the vibration causes resonance due to the excitation force, the vibrations will directly reach the elastic members such as the rubber bushings, and this elastic member will not be able to sufficiently damp the vibrations, resulting in large amplitude vibrations being transmitted to the vehicle body. The dot was hot.

Due to vibration transmission to the car body during this resonance,
Shake, harshness, and axle tramp phenomena were more likely to occur, worsening ride comfort, handling stability, and cabin noise.

(Means for solving the problem) The present invention was made with the purpose of solving the above-mentioned problems.To achieve this purpose, the present invention has a The unsprung member includes a non-rotating unsprung member that rotatably supports the wheels of the vehicle. In a suspension device that supports a drive shaft that connects an allencial gear and each of the left and right wheels, and has a buffer member interposed between the unsprung member and the vehicle body, the suspension device surrounds the outer periphery of the unsprung member, and An annular mass body is provided independently in the left-right direction of the vehicle via an elastic body, and both the elastic body and the annular mass body have a symmetrical shape with respect to a central axis of the unsprung member passing through the rotation center of the left and right wheels. , the vertical elasticity, the longitudinal elasticity, and the rotational elasticity of the elastic body are used as springs,
A dynamic damper is formed by using the annular mass bodies as respective masses.

(Function) Therefore, in the suspension device of the present invention, as described above, the dynamic damper is constructed by using the vertical elasticity, the longitudinal elasticity, and the rotational elasticity of the elastic body as springs, and using the annular mass body as the respective masses. Therefore, the longitudinal resonance frequency of the dynamic damper is the longitudinal resonance frequency of the unsprung member, the vertical resonance frequency is the vertical resonance frequency of the unsprung member, and the rotational resonance frequency is the rotational resonance frequency of the unsprung member. By setting these values, it is possible to suppress resonance in three directions, that is, the vertical direction, the longitudinal direction, and the rotational direction, of the unsprung member by the dynamic damper action.

In addition, since both the elastic body and the annular mass have symmetrical shapes with respect to the axis that passes through the rotation centers of the left and right wheels, the elastic center of the elastic body and the center of gravity of the annular mass are located on the axis that passes through the rotation centers of the left and right wheels. However, when the annular mass body is damping the unsprung resonance, the annular mass body itself can be prevented from vibrating in directions other than the vibration input direction.

In addition, since the mass body is annular in shape and the elastic body is surrounded by the mass body, the mass body will not fall from the unsprung member even if the elastic body is broken due to excessive torsion, compression, tensile force, etc.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In describing this embodiment, a four-link + lateral rod type suspension device used as a rear suspension of a rear-wheel drive vehicle will be taken as an example.

First, the configuration of the embodiment will be explained with reference to FIGS. 1 to 4.

1 is a 4-link + lateral rod type suspension device, as shown in Fig. 2, it includes a rear axle case 2 (corresponding to the unsprung member), upper links 3, 3, lower links 4, 4, lateral rods 5, and coil springs 6. , 6 (equivalent to a buffer member),
It is equipped with shock absorbers 7, 7 (corresponding to buffer members).

The rear axle case 2 has shaft portions 201, 2
01 and a differential section 202, the differential section 202
A differential gear is housed inside the shaft portion 201, and a drive shaft 8 connected to the differential gear is inserted inside the shaft portion 201.

Incidentally, brake drums 9, 9 on which wheels 10 are mounted are connected to both ends of the drive shaft 8.

The above-mentioned Atsupa link 3 and the above-mentioned lower link 4 are
They support the load in the longitudinal direction of the vehicle, and both have one end supported by the rear axle case 2 and the other end supported by the vehicle body.

Note that the two upper links 3, 3 and the two lower links 4, 4 are arranged parallel to the longitudinal direction of the vehicle, respectively.

The lateral rod 5 supports the lateral load of the vehicle, and like the upper link 3 and the lower link 4, one end is supported on the rear axle case 2 and the other end is supported on the vehicle body.

Note that this lateral rod 5 is arranged parallel to the axle case 2.

Furthermore, rubber bushings (not shown) are interposed in the case side support portions and vehicle body side support portions of the upper links 3, 3, lower links 4, 4, and lateral rods 5, respectively.

The coil spring 6 and the shock absorber 7 support the load in the vertical direction of the vehicle, and the coil spring 6, the rubber seat, and the shock absorber 7 are supported by the vehicle body via a mounting insulator. .

In this embodiment, the rear axle case 2 is used as an unsprung member, and two dynamic dampers are formed on the shaft portions 201, 201 of the rear axle case 2 in parallel to the longitudinal direction of the vehicle.The configuration is as follows. state

The shaft portion 201 of the rear axle case 2 has a first
As shown in the figure, an annular rubber bush (elastic body)
An annular weight (annular mass body) 13 is provided in the longitudinal direction of the vehicle via the rubber bush 12, and the longitudinal elasticity, the vertical elasticity, and the rotational elasticity of the rubber bush 12 are used as springs, and the weight 13 is used as the mass of each to form a dynamic damper. is formed.

The rubber bush 12 is fixed to the rear axle case 2 and the weight 13 with an adhesive, and is provided with hollows 14, 14 at two locations above and below to reduce the spring constant in the vertical direction.

With the above-described structure, the center of elasticity of the rubber bushing 12 and the center of gravity of the weight 13 are located approximately on the axis of the drive shaft 8, which is the axis passing through the centers of rotation of the left and right wheels 10, which serve as the input center of the unsprung members.

In this embodiment, the vertical resonance frequency ₀₁ of the dynamic damper is the rear axle case 2.
The resonance frequency ₁ (12Hz) in the vertical direction is equal to the resonance frequency ₀₂ (20Hz ₎ in the longitudinal direction.
Hz), and the rotational direction resonance frequency ₀₃ is set to match the rotational direction resonance frequency ₃ (40Hz).

This setting is performed by tuning the vertical spring constant K ₁ , the longitudinal spring constant K ₂ , and the rotational spring constant K ₃ of the rubber bush 12.

In other words, the resonance frequency ₀ of the dynamic damper is expressed by the equation shown below.

₀ = 1/2π√K/M M: Mass due to weight 13 K (K ₁ , K ₂ , K ₃ ): Spring constant due to rubber bush 12 Therefore, the resonance frequency ₀ is first calculated by weight 1
3 determine the mass, and the spring constants in each direction K ₁ , K ₂ ,
Tuning is performed by determining the material and shape of the rubber bush 12 so as to obtain K ₃ .In the embodiment, hollows 14 are provided at the top and bottom of the rubber bush 12 to reduce the vertical spring constant K ₁ of the rubber bush 12. This is because the vertical resonance frequency ₁ of the rear axle case 2 is as low as 12Hz.

Next, the operation of the embodiment will be explained.

First, a case where vertical vibration input is applied to the rear axle case 2 will be described.

When the frequency at this time approaches the vertical resonant frequency ₁ of the rear axle case 2, the dynamic damper begins to resonate vertically, and when the resonant frequency is ₁ , the resonance is greatest.

Due to this vertical resonance, the vibration energy is converted into deformation energy that causes the rubber bush 12 to elastically deform (compress, tension, twist) in the vertical direction (dynamic damper action), and the rear axle case 2
is damped, and vertical resonance under the spring is reduced.

Incidentally, as shown in FIG. 3, in the suspension device of the embodiment, the peak value of the unsprung vertical acceleration (indicated by the solid line A) in the front and back region of the vertical resonance frequency ₁ (12 Hz) of the rear axle case 2 is lower than that of the conventional suspension device. This can be significantly reduced compared to the acceleration characteristics (indicated by the broken line B).

This shows that by making the vertical resonant frequency ₁ and the vertical resonant frequency ₀₁ of the dynamic damper substantially coincide with each other, a high damping effect can be obtained by the dynamic damper action.

Next, a case where vibration input in the longitudinal direction is applied to the rear axle case 2 will be described.

When the frequency at this time approaches the longitudinal resonance frequency ₂ of the rear axle case 2, the dynamic damper begins to resonate longitudinally, and when the resonance frequency is ₂ , the resonance becomes the largest.

Due to the longitudinal resonance of this dynamic damper, vibration energy is converted into deformation energy of the rubber bush 12 (dynamic damper action), the rear axle case 2 is damped, and the longitudinal resonance under the spring is reduced.

Next, a case where vibration input in the rotational direction is applied to the rear axle case 2 will be described.

When the frequency at this time approaches the rotational direction resonance frequency ₃ of the rear axle case 2, the dynamic damper begins to resonate in the rotational direction, and when the resonance frequency is ₃ , the resonance becomes the largest.

Due to the rotational direction resonance of this dynamic damper, vibration energy is converted into deformation energy of the rubber bush 12 (dynamic damper action), the rear axle case 2 is damped, and the rotational direction resonance of the unsprung portion is reduced.

Incidentally, as shown in FIG. 4, in the suspension device _of the embodiment, _the unsprung longitudinal acceleration (solid line C) is compared with the conventional acceleration characteristic (dotted line D
) can be reduced from the peak value of

Furthermore, in this embodiment, since the elastic center of the rubber bush 12 and the center of gravity of the weight 13 are located approximately on the axis of the drive shaft 8, the weight 13 itself moves in the vibration input direction when suppressing unsprung resonance. For example, when the weight 13 is damping vibration in the vertical direction,
Since the weight 13 also vibrates in the rotational direction and does not impart rotational vibration to the rear axle case 2, it is possible to prevent the noise inside the vehicle from worsening due to this.

Furthermore, since the dynamic dampers are provided independently in the left-right direction of the vehicle, the rubber bushings 12 and weights 13 can be formed individually symmetrically with respect to the axis passing through the center of rotation of the left and right wheels 10. Easy to design, manufacture, and attach to unsprung members.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, an example was shown where the application was applied to a rear suspension device of a rear-wheel drive vehicle, but it may also be applied to a front suspension device of a front-wheel drive vehicle, or a rear suspension device or a front suspension device of a four-wheel drive vehicle, or both. It may be applied to suspension devices.

Further, in the embodiment, a rubber bushing is used as the elastic body, but a spring may also be used.

Further, in the embodiment, the axle case is shown as the unsprung member, but the unsprung member is not limited to the axle case as long as it is a non-rotating unsprung member provided in the left-right direction of the vehicle.

(Effect of the invention) As explained above, in the suspension device of the invention, the vertical elasticity, longitudinal elasticity, and rotational elasticity of the elastic body are used as springs, and the annular mass body is used as the mass, and the dynamic damper is used. Because of this structure, it is possible to suppress resonance in the three directions of the unsprung member, that is, the vertical direction, the longitudinal direction, and the rotational direction, with one dynamic damper.

Further, since the mass body has an annular shape, even if the elastic body is cut, it is possible to prevent the mass body from falling from the unsprung member.

In addition, since both the elastic body and the annular mass body are symmetrical with respect to the axis passing through the rotation centers of the left and right wheels, the elastic center of the elastic body and the center of gravity of the annular mass body are on the axis passing through the rotation centers of the left and right wheels. position, and when the annular mass body is damping unsprung resonance, the annular mass body itself is prevented from vibrating in directions other than the vibration input direction, and the noise inside the car is reduced due to this. The effect is that it can be prevented.

In addition, the unsprung member is provided with independent parts in the vehicle left and right direction.
Since the annular mass body is provided through the elastic body, it is only necessary to form the elastic body and the annular mass body in a symmetrical shape with respect to the axis passing through the center of rotation of the left and right wheels individually, and these elastic bodies and centers of gravity The effect is that it is possible to easily align the axis approximately with the axis passing through the center of rotation of the left and right wheels.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of the suspension device according to the embodiment of the invention, Fig. 2 is a perspective view showing the suspension device according to the embodiment of the invention, and Fig. 3 is the vertical acceleration under the spring in the embodiment device. Characteristic diagram,
FIG. 4 is a characteristic diagram of unsprung longitudinal acceleration in the embodiment device, and FIG. 5 is a perspective view showing a conventional suspension device. 1... 4 links + lateral rod type suspension device (suspension device), 2... Rear axle case (unsprung member), 12... Rubber bush (elastic body), 13... Weight (mass body).

Claims (1)

[Claims for Utility Model Registration] A non-rotating unsprung member is provided in the left-right direction of the vehicle and rotatably supports the left and right wheels, the unsprung member having a hollow portion penetrating in the left-right direction of the vehicle,
supporting a differential gear within the hollow portion and supporting a drive shaft that connects the differential gear to each of the left and right wheels;
In the suspension device in which a buffer member is interposed between the unsprung member and the vehicle body, an annular mass body is provided via an elastic body to surround the outer periphery of the unsprung member and independently in the left-right direction of the vehicle, Both the elastic body and the annular mass body have a symmetrical shape with respect to the central axis of the unsprung member passing through the center of rotation of the left and right wheels, and the vertical elasticity, the longitudinal elasticity, and the rotational elasticity of the elastic body are expressed as a spring. A suspension device characterized in that a dynamic damper is formed by using the annular mass bodies as respective masses.