JPH11141601A - Axle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce in-cabin noise due to the resonance of a wheel. SOLUTION: A dynamic damper 30 is mounted on a wheel supporting member, which is moving coincident with the movement of the rotation shaft of a wheel 10, and for turnably supporting the wheel 10. An axle carrier 18 can correspond to the wheel supporting member in any Macpherson strat type suspension of an idling wheel. In-cabin noise can be effectively reduced, because vibration can be suppressed before the vibration is transmitted and diffused to the respective members of the suspension.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reducing noise entering a vehicle cabin from a wheel of a vehicle, and more particularly to a technique for reducing noise caused by resonance of a wheel.

[0002]

2. Description of the Related Art When a vehicle is running, vibrations generated by unevenness of a road surface or unevenness of a tread pattern of a wheel tire are input to a vehicle body via a suspension member or the like.
It excites the resonance system of each member and generates noise. In particular, when the steel plates constituting the vehicle body resonate, a large noise is generated inside the vehicle. Wheel vibration is input to the vehicle body from mounting points on the vehicle body, such as suspension arms, suspension links, suspension springs, and shock absorbers.Therefore, the path is complicated and numerous, and sufficient noise reduction is required unless the source vibration is reduced. No effect can be expected.

[0003] In order to suppress the source, ie, the vibration of the wheel, particularly the vibration at the time of the resonance of the wheel, a technique of reducing the amplitude of the resonance by providing a ring-shaped dynamic damper on the outer periphery of the rim of the wheel of the wheel, ie, inside the tire. JP-A-54-1
No. 48969.

[0004]

However, when the vehicle is running, not only the wheels are simply rotating, but also the rotating shaft is moving in the traveling direction of the vehicle. Thus, the trajectory of a point on the wheel will describe a trochoid, and that point will experience a periodically changing inertial force.
The weight portion of the dynamic damper described in the publication also receives this periodically changing force. by this,
In some cases, resonance of the dynamic damper occurs, which is transmitted to the vehicle body and becomes a new noise source.

A dynamic damper achieves a vibration damping effect by vibrating in a phase opposite to that of a member to be damped at the time of resonance, but the direction of the vibration changes every moment due to the rolling of the tire. However, the above-described vibration damping effect cannot be expected.

Further, by installing a dynamic damper, there is a possibility that the balance of the wheels is lost and vibration is generated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to effectively suppress the vibration related to the resonance of the wheels and reduce the noise caused by the vibration.

[0008]

In order to solve the above-mentioned problems, an axle according to the present invention is mounted on a wheel supporting member which moves in accordance with the movement of a wheel rotating shaft and rotatably supports a wheel. , A dynamic damper is attached.

The wheel support member is a member that is close to a vibration source, that is, a wheel, and connects each member constituting a suspension and a member constituting a wheel. By damping the vibration before it disperses, Vibration can be effectively prevented from entering the vehicle body. In addition, since the member is not a member that rotates with the wheel, vibration due to rotation and rolling does not occur.

The wheel supporting members differ depending on whether the vehicle suspension system is an axle suspension system or an independent suspension system, and whether or not a vehicle includes a steering mechanism. Hereinafter, specific examples of the wheel support member will be described.

Independent suspension system In the case of an axle including a steering mechanism of a vehicle employing an independent suspension system, a wheel hub that rotates with wheels is supported via bearings, and a steering knuckle that rotates around a kingpin corresponds to a wheel support member. I do. In the case of an axle that does not include a steering mechanism, an axle carrier (also called a hub carrier) that supports via a bearing a wheel hub that rotates with the wheels corresponds to the wheel support member.

The steering knuckle can be said to be a hub carrier that turns around a kingpin. Also, when the hub carrier is integrated with other parts, such as the trailing arm of a full trailing type or semi-trailing type suspension or the lower strut of a MacPherson strut, this part also supports the wheel support. It corresponds to a member.

[0013] When the axle suspension system axle of a vehicle employing an axle suspension system, the axle housing corresponds to the wheel support member. In particular, in those including the steering mechanism, the steering knuckle also corresponds to the wheel support member. Since a tie rod or the like is connected to the steering knuckle, it is more preferable to control the steering knuckle in consideration of an input from the tie rod.

Further, even in the case of an axle suspension type, in the case of a type having no axle housing such as a de Dion type, a beam member connecting left and right wheels corresponds to a wheel supporting member.

Although the above is a specific example, the wheel supporting member is not limited to these.

Further, it is preferable that a member near the wheel rotating shaft serving as a vibration transmission path from the wheel, which is provided at a position before the vibration is dispersed, is used as the wheel supporting member. Thereby, vibration can be effectively reduced.

The dynamic damper includes a weight and a spring member that couples the weight to a member to be damped. Preferably, the spring member has a damping characteristic. The weight may be of any material as long as it has an appropriate mass, but preferably has a high density and a low price. In this sense, cast iron and the like are preferable. For density,
A high density is desired to reduce the space for obtaining the required mass. As long as the spring member has a predetermined spring constant, a coil spring, a plate spring, a torsion bar spring, or the like made of steel or the like may be used, or a rubber material may be used. When formed of a rubber material, the spring constant can be adjusted to some extent independently for each direction, such as the compression / extension direction and the shear direction, by adjusting the components and the cross-sectional shape. In addition to the spring member,
It is also possible to separately provide a member having a damping characteristic and adjust the damping coefficient independently.

Generally, the mass and the spring constant of the weight of the dynamic damper are determined so that the resonance frequency of the dynamic damper matches the frequency of the vibration to be damped. However, the resonance frequency of the dynamic damper at which the optimum damping effect is obtained by matching with the damping characteristic of the rubber member does not necessarily have to match the resonance frequency of the damping target.

[0019]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings. 1 and 2 are schematic structural views of the vicinity of an axle of a McPherson strut type suspension. FIG. 1 is a front view, FIG.
Is a side view. The wheel 10 includes a tire 12 and a tire 1
2 supporting wheel 2 and coupled to wheel hub 14
Contains. The wheel hub 14 is rotatably supported by an axle carrier 18 via a bearing (not shown). The axle carrier 18 is bifurcated into upper and lower parts as shown in the figure, and a strut 2 including a coil spring (not shown) and a shock absorber is provided on an upper part thereof.
The lower end of 0 is connected. The upper end of the strut 20
Fixed to the body. Further, two lower links 22 extending in the left-right direction of the vehicle are pivotally connected to the lower end of the axle carrier 18 at the connection points. The other end of the lower link 22 is pivotally connected to a suspension subframe 24 (see FIG. 4) at a connection point. The lower link 22 restricts mainly the movement of the axle carrier 18, that is, the movement of the wheel 10 in the vertical direction while allowing the movement of the wheel 10 in the vertical direction. A strut rod 26 extending in the vehicle front-rear direction is also pivotally connected to a lower end of the axle carrier 18 at a connection point, and the other end thereof is rotatably connected to a vehicle body or a subframe at a connection point.

In the axle having the above-described structure, when the wheel 10 rolls, the wheel 10 is vibrated by the unevenness of the tread pattern of the tire 12 and the unevenness of the road surface 28, and the strut 20, the lower link 22, and the strut rod 26 are vibrated.
Input to the vehicle body via suspension parts such as. When the frequency of the input from the road surface 28 to the wheel 10 matches the resonance frequency of the vibration system of the wheel 10, the wheel 10 resonates, and this vibration is input to the vehicle body along the above-described transmission path. Of the resonance of the vibration system of the wheel 10, the problem is
Tire elastic resonance caused by the elasticity of the tire 12, tire cavity resonance that is the resonance of air trapped inside the tire 12, and wheel resonance in which the entire wheel 10 vibrates with the bearing that supports the wheel hub 14 acting as a spring.

In the present embodiment, the dynamic damper 30 set to at least one of these resonance frequencies is mounted on the axle carrier 18 which is a member sufficiently rigid with respect to this resonance frequency. The dynamic damper 30 has a weight 32 and a rubber spring 34 interposed between the weight 32 and the axle carrier 18. The resonance frequency of the dynamic damper 30 can be adjusted to some extent for each direction of vibration by adjusting the shape and composition of the rubber spring 34. The above three types of resonance are mainly represented by the tire elastic resonance in the vertical direction, the tire cavity resonance in the front and rear direction and the vertical direction, and the wheel resonance mainly in the left and right direction.
The resonance frequency and the damping constant for each direction of 0 are adjusted so as to obtain the vibration reduction effect of each resonance. In the vertical characteristics of the dynamic damper 30 of the present embodiment, the resonance frequency is adjusted to 225 Hz from the spring constant and the damping constant of the rubber spring 34 in order to suppress the tire cavity resonance that appears in the vertical direction. FIG. 3 shows the frequency characteristics of the dynamic damper used in the present embodiment. In the case of this damper, since the damping constant is large, the frequency (250 H
z) is the resonance frequency (225H) at which the amplitude level has a peak.
z), but the phase is almost -1 around 250 Hz.
Since the angle is 80 degrees, the damping effect can be increased.

The characteristics of the axle and the suspension of this embodiment were measured by the apparatus shown in FIG. The vehicle body-side connection points of the respective members of the suspension are connected to predetermined positions of a test frame 36 simulating the vehicle body so as to have the same alignment as when mounted on the vehicle body. One of the wheels 10 is mounted on a vibrator 38. The vibration of the vibration exciter 38 simulates an input due to rolling of a wheel or the like. FIG. 5 shows the frequency characteristics measured at the top of the strut by the apparatus shown in FIG. The horizontal axis is frequency, and the vertical axis is transfer function (inertance). The characteristics at the time of mounting the damper shown by the solid line are different from those at the time of non-mounting shown by the broken line
It can be confirmed that the inertance is reduced by 3 to 5 dB.

FIGS. 6 and 7 show the effect of the dynamic damper 30 when a vehicle employing the axle and suspension of the present embodiment travels on a normal road surface at a vehicle speed of 60 km / h. The effect of reducing the vibration level by 2 to 3 dB, and the noise in the cabin, especially in the resonance frequency region, is 3 dB.
The effect of reducing dB can be confirmed.

In the above-described embodiment, the frequency of the dynamic damper is adjusted to the frequency of the tire cavity resonance in the vertical direction.
(100 Hz) to reduce the vehicle interior noise of this frequency.

The mounting position of the dynamic damper 30 is not limited to the position shown in FIG. 1 and the like. It may be. FIG.
2 and the lower end of the strut 20 is fixedly connected to the axle carrier 18 as shown in FIG.
It is also possible to provide a dynamic damper 40 in this part.

Further, as shown in FIGS. 9 and 10, the directions of the dynamic dampers 42 and 44 can be changed to cope with resonance in different vibration directions.

Further, as shown in FIG. 11, a plurality of dynamic dampers 46, 48 and 50 can be mounted so as to correspond to a number of resonance points.

Further, as shown in FIG.
It is also possible to mount a dynamic damper 52 having a weight-rubber spring-weight and a two-stage stack, so that the adjustment frequency of each stage is different.

Further, instead of a dynamic damper comprising a rubber spring and a weight, a leaf spring 56 as shown in FIG.
The dynamic damper 54 having the weight 58 can also be used. The leaf spring 56 can suppress the amplitude of the weight 58 by using a sandwich damping steel plate.

The case where the wheel supporting member is an axle carrier or a strut has been described above. However, in the case of another axle configuration or suspension type, a member to which a dynamic damper is attached, that is, a wheel supporting member is different according to the configuration. .

[Brief description of the drawings]

FIG. 1 is a front view illustrating a schematic configuration of a part of an axle and a suspension according to an embodiment.

FIG. 2 is a side view showing a schematic configuration of a part of the axle and suspension of the embodiment.

FIG. 3 is a diagram illustrating vibration characteristics of a dynamic damper according to the present embodiment.

FIG. 4 is a diagram showing an outline of a test device for vibration characteristics.

FIG. 5 is a diagram showing the vibration characteristics of the axle of the present embodiment, measured by the test device of FIG.

FIG. 6 is a diagram illustrating vibration characteristics measured during actual running of a vehicle equipped with the axle according to the present embodiment.

FIG. 7 is a diagram showing vehicle interior noise characteristics measured during actual running of a vehicle equipped with the axle of the present embodiment.

FIG. 8 is a diagram showing an example of changing a mounting position of a dynamic damper.

FIG. 9 is a diagram showing an example in which the mounting direction of the dynamic damper is changed to change the direction of vibration to be damped.

FIG. 10 changes the mounting direction of the dynamic damper,
It is a figure showing the example which changed the direction of the vibration which should be controlled.

FIG. 11 is a diagram showing an example in which a plurality of dynamic dampers are mounted.

FIG. 12 is a diagram showing an example in which a two-stage dynamic damper is mounted.

FIG. 13 is a diagram illustrating an example in which a dynamic damper including a leaf spring of a damping steel plate and a weight is mounted.

[Explanation of symbols]

10 wheels, 12 tires, 14 wheel hubs, 16
Wheels, 18 axle carriers (wheel support members), 20 struts, 28 road surfaces, 30-54 dynamic dampers.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Minoruaki Nakagawa 41-Cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Ichiro Kido 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (1)

[Claims] 1. A wheel axle supporting a wheel via a suspension with respect to a vehicle body, the wheel supporting member moving in accordance with the movement of a wheel rotation axis, and supporting the wheel rotatably; An axle having a dynamic damper attached to the support member.