JPH0529564Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a dynamic damper mounting structure that effectively reduces drive shaft bending vibration, which causes final drive gear noise, without being affected by shaft rotation fluctuations. Regarding.

(Prior Art) Conventionally, as a front wheel drive unit of an automobile, for example,
Structures as shown in Figures 3 and 4 are known (``Automotive Engineering Handbook'', Vol. 5, 1-37, 1).
-10).

This is an independent suspension drive front axle.
Since the final reduction gear is attached to the vehicle body,
Universal joints are provided on both the vehicle body side (final reduction gear side) drive shaft and the wheel side drive shaft. That is, a bar field type slide joint 02 is used as a joint on the final reduction gear side of the drive shaft 01, and a bar field type fixed joint 03 is used as a wheel side joint.
is used.

Further, the drive shaft 01 is inserted into a side gear portion 06 of a differential case 05 housed in a final gear case 04, and the differential case 05 is coupled to a final gear 07, and this final gear 0
7 itself transmits driving force to the drive shaft 01.

Therefore, the meshing forcing force of the final gear 07 causes bending resonance in the drive shaft 01, which becomes a problem as final gear noise. That is, bending vibration as shown in FIG. 5 occurs in the drive shaft 01, and this vibration excites vehicle body vibration through the suspension, increasing the noise inside the vehicle due to sound radiated from the vehicle body panel.

In order to absorb the above-mentioned bending vibrations, a structure in which a dynamic damper is attached directly to the drive shaft (rotating shaft) has been proposed (``Automobile Engineering Complete Book Volume 9 Power Transmission Devices'') published in 1982. ; 340 pages, Figure 6, 11).

(Problems to be solved by the invention) However, when a dynamic damper is directly attached to a drive shaft (rotating shaft), there are problems as listed below.

According to the inventors' experimental analysis, the direction in which the bending vibration of the drive shaft is generated is always the same even though it is rotating.

The reason for this is thought to be that the point at which the excitation force is applied is an engagement point that is fixed in space and does not rotate together with the drive shaft.

Therefore, when the coordinates are moved onto the rotating drive shaft, the vibration is not at the original meshing frequency but at a frequency of ±ω/2π (ω: rotational angular velocity of the drive shaft).

This is because, as shown in Figure 6, when a sinusoidal vibration that occurs along one coordinate axis is observed with relatively rotating coordinates, the first-order frequency of the rotation shifts, producing a "beat". It corresponds to what appears to be.

In FIG. 6, y is the coordinate axis on the drive shaft, and y' is the coordinate axis of the stationary system. It is assumed that the excitation force acts along the y' axis. Furthermore, in FIG. 6, the rotational coordinate system is fixed. mω ₀ is the excitation frequency (meshing frequency), ω ₀ is the rotational angular velocity, and the amplitude of the excitation force is set to 1. As shown in the figure, the driveshaft has a "beat" on the axis of time t.
waveform and moved ±ω ₀ on the frequency ω axis 2
It can be seen that it is converted into components.

As a result of the above, bending vibrations occur at two frequencies on the drive shaft.

However, since a dynamic damper fixed to a rotating shaft has only one resonance point, it is difficult to produce an effect at both frequencies. Further, as shown in FIG. 6, the interval between the two components of the vibration frequency changes depending on the rotational speed ω ₀ , but since the resonance point of the damper is fixed, it is not possible to follow this and exert the damper function.

Therefore, even under the best conditions, only one frequency component can be suppressed, leaving the other frequency component.

If a dynamic damper, such as a dynamic damper, is installed with a structure that protrudes from the rotating shaft, if ice forms on the dynamic damper during cold weather, the ice will grow due to centrifugal force, causing damage to piping, etc. The problem arises.

In addition to the final gear noise mentioned above, there is also an abnormal noise phenomenon caused by similar bending resonance of the drive shaft when the engine rotates at high speed, which deteriorates the quality of the vehicle.

Note that the mechanism of this abnormal noise is similar to that shown in FIG.

The present invention was developed focusing on the above-mentioned problems, and it is possible to reliably perform the damper function against the bending resonance phenomenon of the rotating shaft, as well as to improve safety against icing phenomena and during high-speed rotation. The objective is to develop a dynamic damper mounting structure that can also prevent abnormal noise.

(Means for Solving the Problems) In order to solve the above problems, in the dynamic damper mounting structure of the present invention, a dynamic damper composed of a mass part and an elastic body is mounted on an automobile drive shaft, which is a rotating shaft. In a mounting structure for a dynamic damper that is attached to a drive shaft to absorb bending vibration of The elastic body is fixed stationary, and its spring stiffness characteristics have a high and low directionality, and the resonance frequency of the dynamic damper is determined by the spring stiffness of the elastic body in the bending vibration direction of the drive shaft and the mass of the mass part. The supporting member was tuned to match the bending characteristic value of the drive shaft, and the stiffness of the supporting member was set to be lower than at least the spring stiffness of the elastic body of the dynamic damper.

(Function) To install the dynamic damper, first, the elastic body, mass portion, outer race of the bearing, and support member are integrally formed, and this integrally molded product is assembled to the inner race of the bearing which is press-fitted and fixed to the drive shaft. Then, when the vehicle is assembled, the dynamic damper is installed by supporting it with the support member against the fixed part present on the outside of the drive shaft.

In addition, since the elastic body has a spring stiffness characteristic with high and low directionality, when the dynamic damper is installed, the dynamic damper is determined by the spring stiffness of the elastic body in the bending vibration direction of the drive shaft and the mass of the mass part. The resonance frequency of the microphone damper is tuned to match the bending eigenvalue of the drive shaft.

The direction of bending vibration that occurs in the drive shaft during running is always in the same direction even though the drive shaft is rotating.

On the other hand, a dynamic damper allows the drive shaft to rotate using a bearing, keeps the elastic body and mass part stationary relative to a fixed part located outside the drive shaft, and drives the dynamic damper in its operating direction. Because it matches the direction of bending vibration of the shaft, the bending vibration of the drive shaft, which causes final drive gear noise, is reduced.
This can be effectively reduced without being affected by shaft rotation fluctuations.

In other words, since the dynamic damper, which is composed of a mass portion and an elastic body, is attached in a stationary fixed state by a support member, the centrifugal force caused by the rotation of the drive shaft does not act on either the mass portion or the elastic body, and since the vibration of the elastic body and the mass portion occurs along the stationary coordinate system, the resonant frequency of the dynamic damper, which is tuned to match the bending eigenvalue of the drive shaft, does not shift due to fluctuations in shaft rotation.

Furthermore, the inner member of the bearing that is directly installed on the drive shaft becomes a rotating part that rotates together with the drive shaft, and the radius of this rotating part can be made small, so there is no mass imbalance in the drive shaft, and the dynamic damper is It will not cause the driveshaft to whirl around.

In addition, the elastic body has a spring stiffness characteristic with high and low directionality, and the spring stiffness of the elastic body in the direction of bending vibration of the drive shaft is used to tune the resonance frequency, which improves vibration absorption of the drive shaft. Sometimes, the mass section swings only in the direction of bending vibration of the drive shaft, and this swing of the mass section does not induce vibrations in other direction components.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

First, the configuration will be explained.

Figures 1 and 2 are diagrams showing the front wheel drive section of a FF vehicle to which the dynamic damper mounting structure of the embodiment is applied, in which 1 is the drive shaft (rotating shaft), which is of an independent suspension system. Since the final reduction gear is attached to the vehicle body, a bar field type slide joint 2 is provided on the final reduction gear side, and
A universal joint (not shown) is also provided on the wheel side.

Further, the drive shaft 1 is inserted into a side gear part 6 of a differential case 5 housed in a final gear case 4,
Differential case 5 is final gear 7
The final gear 7 itself is configured to transmit driving force to the drive shaft 1.

The dynamic damper 10 is composed of an elastic body 11 made of rubber and an annular mass part 12, and the mounting structure of the dynamic damper 10 is as follows.
The elastic body 11 is rotatably supported by the drive shaft 1 via a roller bearing 13 (bearing), and the mass portion 12 is at least as rigid as the elastic body 11 in the bending vibration direction of the drive shaft 1 (approximately the vehicle It is attached by being supported to the power plant outer wall 15 (fixed part) existing outside the drive shaft 1 via a supporting elastic body 14 (supporting member) whose rigidity is lower than the bending rigidity in the vertical direction.

The elastic body 11 is fixed by baking between the outer race 13a of the roller bearing 13 and the inner surface of the mass portion 12, with a space provided in the vertical direction of the vehicle.

The support elastic body 14 is fixed between the outer surface of the mass portion 12 and the bracket 16 by baking.

The bracket 16 is fixed to the power plant outer wall 15 with bolts 18.

Both sides of the roller bearing 13 are sealed to prevent foreign matter from entering.

Next, the effect will be explained.

(a) During installation The dynamic damper 10 is installed using the following procedure.

Elastic body 11, mass part 12, and outer lace 1
3a (roller bearing 13) and supporting elastic body 1
4 and the bracket 16 are integrally baked and molded.

Outer race 13 of roller bearing 13
Machine the bearing part, which is the inner surface of a.

Assemble the inner race and roller of the roller bearing 13 together with the holding fittings and seals.

The inner race and rollers of the roller bearing 13 are press-fitted and fixed to the drive shaft 1.

The dynamic damper 10, which is molded together with the supporting elastic body 14 and the bracket 16, is assembled to the press-fitted roller bearing 13.

When assembling the vehicle, the bracket 16 is fixed to the power plant outer wall 15 with bolts 18.

The dynamic damper 10 is installed according to the above procedure, and after installation, the elastic body 11 and the mass part 1
2 and the roller bearing 13 are assembled in the direction in which the final gear 7 collapses due to the load in the direction of action, that is, in the power plant of a FF vehicle, they are aligned approximately vertically in a straight line, and the dynamic damper in this direction is The resonance frequency (eigenvalue) of the drive shaft 1 is tuned to match the bending eigenvalue of the drive shaft 1.

(b) When driving When driving, bending resonance occurs in the drive shaft 1 due to the meshing force of the final gear 7, which causes a problem as final gear noise. Furthermore, the direction in which the bending vibration of the drive shaft 1 is generated is always the same even though it is rotating.

On the other hand, the dynamic damper 10 allows the drive shaft 1 to rotate using the roller bearing 13, and is fixed to the power plant outer wall 15 via the supporting elastic body 14, so that it can be used in a stationary state, and the damper's action is Since the direction is limited to one direction above and below the vehicle when viewed from the stationary coordinate system, it is possible to cope with the fact that the bending vibration of the drive shaft 1 always occurs only in a fixed direction as described above.

Therefore, the tuning characteristic value of the dynamic damper 10 does not deviate regardless of the rotational speed of the drive shaft 1.
The damper function can be reliably exerted in response to the bending resonance phenomenon.

In addition to the final gear noise mentioned above, when the engine rotates at high speed, abnormal noise is generated due to similar bending resonance of the drive shaft 1, but this abnormal noise is caused by the statically provided elastic body 11 and supporting elastic body This abnormal noise is also reduced due to the double noise energy absorption effect.

(c) When icing occurs If a structure such as the dynamic damper 10 is provided that protrudes from the drive shaft 1, icing will occur on the dynamic damper 10 during cold seasons.
Since this dynamic damper 10 does not rotate together with the drive shaft as in the conventional case, ice does not grow due to centrifugal force, and problems such as damage to piping etc. due to the growing ice do not occur. .

As explained above, in the mounting structure of the dynamic damper 10 of the embodiment, it is possible to reliably perform the damper function against the bending resonance phenomenon of the drive shaft 1, and also to ensure safety against the icing phenomenon. It is also possible to prevent abnormal noises during high-speed operation.

Although the embodiment has been described above based on the drawings, the specific configuration is not limited to this embodiment, and any design changes, etc. that do not depart from the gist of the present invention are also included in the present invention. .

Further, in the embodiment, an example of a support elastic body made of a rubber material is shown as a support member supported by a fixed part, but a metal spring or the like may also be used.

(Effects of the invention) As explained above, in the present invention, in the mounting structure of the dynamic damper attached to the rotating shaft, the dynamic damper can be mounted on the drive shaft as stated in the claims of the utility model registration. The spring stiffness in the bending vibration direction of the drive shaft is an elastic body that is provided via a bearing and fixed stationary by a support member to a fixed part existing outside the drive shaft, and has a spring stiffness characteristic with high and low directionality. The resonance frequency of the dynamic damper, which is determined by the mass of the mass part, is tuned to match the bending eigenvalue of the drive shaft, and the rigidity of the support member is set to at least lower than the spring rigidity of the elastic body of the dynamic damper. The effect is that drive shaft bending vibration, which is a cause of final drive gear noise, can be effectively reduced without being affected by shaft rotation fluctuations.

In addition, safety against icing phenomena and prevention of abnormal noises during high-speed rotation can also be achieved.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view showing the front wheel drive section of a FF vehicle to which the dynamic damper mounting structure of the present invention is applied, and Fig. 2 is a diagram showing the dynamic damper mounting structure of the embodiment taken along the line shown in Fig. 1. 3 is a sectional view showing the front wheel drive section of a generally known FF vehicle, FIG. 4 is a view showing the drive shaft (front wheel drive shaft), and FIG. 5 is an explanatory diagram of the bending vibration phenomenon of the drive shaft. FIG. 6 is a diagram illustrating that when the rotational coordinate system is fixed, the direction in which bending vibration occurs is always constant. 1... Drive shaft (rotating shaft), 2... Bar field type slide joint, 4... Final gear case, 5... Differential case,
6...Side gear section, 7...Final gear, 1
0...Dynamic damper, 11...Elastic body, 1
2...Mass part, 13...Roller bearing (bearing), 14...Supporting elastic body (supporting member), 15...
Power plant outer wall (fixed part).

Claims (1)

[Scope of Claim for Utility Model Registration] In a dynamic damper mounting structure in which a dynamic damper composed of a mass part and an elastic body is attached to a drive shaft for absorbing bending vibrations of an automobile drive shaft, which is a rotating shaft. , the dynamic damper is provided to the drive shaft via a bearing, and fixed stationary to a fixed part existing outside the drive shaft by a support member; The resonance frequency of the dynamic damper, which is determined by the spring stiffness of the elastic body in the bending vibration direction of the drive shaft and the mass of the mass part, is tuned to match the bending eigenvalue of the drive shaft, and the rigidity of the support member is tuned. A mounting structure for a dynamic damper, characterized in that the rigidity is set to be lower than at least the spring rigidity of an elastic body of the dynamic damper.