JPS61202907A - Rear suspension of car - Google Patents

Abstract

PURPOSE:To lessen the vibration of a sub-frame by differentiating the natural frequencies between a pair of right and left longitudinal member parts of a sub-frame to which the inner ends of plural lateral links supporting a wheel support are connected. CONSTITUTION:The captioned rear suspension whose base end is rotatably installed on a body side 16, consists of a swing arm 18 on which a wheel support 12 on the end of which a rear wheel 10 is rotatably supported, is mounted, three lateral links 20, 22, 24 whose outer ends are connected to the wheel support 12 while whose inner ends are connected to the body side 16, and which are extending in the lateral direction of body, and a sub-frame 28. The sub- frame 28 consists of a pair of right and left longitudinal member parts 30, and two lateral members 36, 38. And, the right and left longitudinal member parts 30 are formed in such a way that their natural frequencies are differentiated from each other and, thereby, the vibration of the sub-frame 28 can be lessened, reducing a humming sound.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a rear suspension for an automobile.

(Prior Art) One type of independent rear suspension for automobiles is a so-called trailing arm type.

This type of rear suspension has a trailing arm arranged in the longitudinal direction of the vehicle body, and the base end of the arm is rotatable toward the vehicle body, that is, the arm swings in the vertical direction of the vehicle body around the base end. The arms are movably connected, the tip of the arm is fixed to a wheel support that rotatably supports the rear wheel, and a shock absorber is disposed between the tip of the arm and the vehicle body side above it.

This type of rear suspension has a simple structure and can be lightweight, but since the lateral load acting on the rear wheel is supported by the trailing arm itself, it is difficult to maintain sufficient lateral rigidity of the arm. Therefore, there is a problem in that the arm becomes larger and the weight increases.

A structure that solves these problems was developed in U.S. Pat. No. 56-6220
It is disclosed in Publication No. 5. This disclosed structure includes, in addition to the trailing arm disposed between the vehicle body side catcher wheel support and the vehicle body side handler wheel support as described above, two trailing arms located above and below the vehicle body disposed roughly in the lateral direction of the vehicle body. A lateral link is provided, the outer ends of both lateral links are rotatably connected to the tip of the trailing arm, and the inner ends of both lateral links are rotatably connected to the vehicle body side. The rear suspension with this structure has two lateral links, so there is no need to increase the lateral rigidity of the trailing arm, and the inner ends of both lateral links can be attached to the vehicle body at 19! This has the advantage of making it easy to adjust the camber angle, but on the other hand, if the rear wheel moves vertically relative to the vehicle body, it will be difficult to adjust the camber angle when moving upward, i.e., during bumps, and when moving downward, i.e., during rebound. However, since the rear wheels tend to move in the toe-out direction, there is a problem that running instability such as oversteer occurs when driving on a curved road.

Therefore, the present applicant has previously filed an application for a rear suspension structure that also solves this problem. The rear suspension according to this application includes a swing arm disposed in the longitudinal direction of the vehicle body and three lateral links disposed in the lateral direction of the vehicle body, and the base end of the swing arm rotates toward the vehicle body. (swingable in the vertical direction of the vehicle body in a vertical plane in the longitudinal direction of the vehicle body around an axis in the lateral direction of the vehicle body at the base end), and the tip is connected to a wheel support that rotatably supports the rear wheel. For example, the swing arm is configured to receive rotational force and longitudinal force from the wheel support by being fixedly connected, and each inner end of the lateral link is rotated at three points spaced apart from each other on the vehicle body side. They are movably connected, with each outer end being rotatably connected to three mutually spaced points on the wheel support.

In a rear suspension with such a structure, the lateral link receives a lateral load, similar to the conventional rear suspension comprising two lateral links arranged above and below, so the swing arm (corresponding to a conventional trailing arm) In addition to the advantage that lateral rigidity is not so required, it is also possible to suppress the tendency of the rear wheels to toe out when the rear wheels bump or rebound, thus providing excellent running stability.

This is because, according to this configuration, the wheel support, and therefore the posture of the rear wheel, is regulated only by the three lateral links, and the arrangement of the three lateral links,
In other words, by appropriately determining the vertical and longitudinal inclination angles and lengths of each lateral link, the mounting position to the wheel support, and the lateral rigidity at the mounting position, it is possible to prevent the rear wheel from bumping, rebounding, and This is because it becomes possible to control both the toe change and the camber angle change of the rear wheel to a desired tendency when a lateral force or longitudinal force is applied to the wheel.

Of course, in this configuration, as mentioned above, the three lateral links bear the lateral load, and the swing arm carries the force in the longitudinal direction of the vehicle body and the rotational force in the rotational direction of the rear wheels. The swing arm only needs to have the strength and rigidity to transmit these two forces, and it is desirable that no restrictions be placed on the attitude control of the rear wheel by the three lateral links. In other words, when bumping or rebounding, the rear wheels move up and down in an arc in a vertical plane in the lateral direction of the vehicle body, centering on the connection point on the vehicle body side of the lateral link. Therefore, it is desirable that the swing arm does not impose any restraints on the lateral movement of the rear wheel. For this reason, for example, the swing arm may be made of a plate with a vertical cross section that is large in height relative to its thickness. It is necessary to configure the swing arm to allow lateral deflection of the swing arm, or to attach the base end of the swing arm to the vehicle body via a rubber bush.

One aspect of applying a rear suspension consisting of a swing arm and three lateral links as described above to an actual automobile is a pair of left and right vertical members disposed approximately in the IyJv1 direction of the vehicle body, and A subframe is provided which has a horizontal member section that interconnects a pair of vertical member sections, and the subframe is connected to and supported by the vehicle body (this subframe therefore constitutes a part of the vehicle body side). ), a mode is conceivable in which the inner ends of the three lateral links are connected to the left and right vertical member portions, respectively.

However, in this way, the subframe is integrally constructed with a pair of left and right vertical members and a horizontal member that connects them, and the left and right vertical members of this subframe have three left and right lateral links, respectively. If a configuration in which the inner ends are connected is adopted, the left vertical member section will receive an external force from the left lateral link and vibrate, and the right vertical member section will receive an external force from the right lateral link and will take pictures. If the vertical members begin to vibrate strongly at the same frequency at the same time, the left and right vertical members are integrally connected by the horizontal member, so there is a risk that both vibrations will combine and the entire subframe will begin to vibrate greatly. There is also the possibility that the vibration may generate a large muffled sound.

Note that, as a subframe with a lateral link attached, there is one disclosed in, for example, Japanese Patent Laid-Open No. 57-121908.

(Object of the Invention) In view of the above-mentioned circumstances, the object of the present invention is to provide a subframe comprising a pair of left and right vertical member portions disposed substantially in the longitudinal direction of the vehicle body and a horizontal member portion connecting both class member portions, This rear suspension for an automobile is constructed by connecting a plurality of left and right lateral links to the left and right vertical members of the subframe, respectively, and is capable of reducing vibrations of the subframe and muffled noise caused by the vibrations. The purpose is to provide suspension.

(Structure of the Invention) In order to achieve the above object, the rear suspension for an automobile according to the present invention includes a swing arm disposed in the longitudinal direction of the vehicle body as described above, and a plurality of lateral links disposed in the lateral direction of the vehicle body. and a sub-frame that is supported by the vehicle body and consists of a pair of left and right vertical member portions arranged approximately in the front-rear direction of the vehicle body and a horizontal member portion that connects the two-class member portions, and is supported by the vehicle body. The inner ends of the three lateral links are connected to each other, and the two class member parts are configured so that their natural frequencies are different from each other.

(Effects of the Invention) As described above, in the automobile rear suspension according to the present invention, the natural frequencies of the left and right subframe vertical member portions to which the left and right lateral links are connected are different. That is, the frequency at which the vertical member resonates due to the external force transmitted via the lateral link differs between the left and right vertical member parts.

Therefore, even if one vertical member begins to resonate and the vibration is transmitted to the other vertical member through the horizontal member, there is no risk that the other vertical member will begin to resonate; The resonance of the one horizontal member is suppressed by the other vertical member having a different natural frequency and connected via the horizontal member. Also,
Even if both vertical members start resonating at their respective natural frequencies, both resonances have a phase difference, so even if they are connected at the horizontal member, they will become one and the entire subframe will be There is no risk of large vibrations starting, but rather, both of the pickups interfere with each other via the lateral member and act in a direction that cancels each other out.

That is, in the rear suspension according to the present invention, it is possible to reduce the vibration of the subframe, and as a result, it is possible to reduce the muffled noise caused by the suspension movement.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 and 2 are diagrams showing an embodiment of a rear suspension for an automobile according to the present invention, and FIG. 1 is a plan view (
Only the right half from center line C is shown.

The left half (not shown) appears symmetrically with the right half. However, regarding the subframe, the left half is also indicated by a chain double-dashed line), the second
The figure is a view seen from the direction of the arrow in FIG. 1.

In this embodiment, as shown in the figure, the rear wheel 10 is rotatably supported by the wheel support 12, and the eggplant pension device 14 is rotatably supported by the wheel support 12.
It is connected to the vehicle body side 16 via. The suspension device 14 includes a swing arm 18, a first lateral link 20, a second lateral link 22, and a third lateral link 2.
4 and a shock absorber 26.

The swing arm 18 has a vertically wide plate shape and extends in the longitudinal direction of the vehicle body, and its base end 18a is attached to a vertical member portion 30 (described later) of a subframe 28 that constitutes a part of the vehicle body side around a horizontal axis 32 in the lateral direction of the vehicle body. Rotatably attached, tip 18b
is fixed to the wheel support 12 using bolts etc.
Therefore, the swing arm 18 can swing up and down within a vertical plane in the longitudinal direction of the vehicle body, centering on its base end 18a. The swing arm base @18a is attached to the vertical member portion 30 via a rubber bushing 34 consisting of a cylindrical rubber, an outer cylinder fixed to the outer periphery of the rubber, and an inner cylinder fixed to the inner periphery. That is, the swing arm base end 18a is fixed to the rubber bushing outer cylinder, and the rubber bushing inner cylinder is rotatable about a horizontal horizontal axis 32 provided on a mounting bracket fixed to the vertical member part 30 and slidable in the axial direction thereof. is fitted in.

First, second and third lateral links 20.22.24
extend substantially in the lateral direction of the vehicle body, and each outer end is provided with a rubber bushing at three points spaced apart from each other on the wheel support 12 so as to be rotatable via a ball joint or approximately around a horizontal axis in the longitudinal direction of the vehicle body. Connected via (20a,
22a and 24a indicate the connection points of the outer ends of each lateral link to the wheel support), and the inner ends of each lateral link are connected to three mutually spaced points of the vertical member 30 of the subframe 28, which is a part of the vehicle body side 16. , Rubber bushing 20G that can rotate around the horizontal axis in the longitudinal direction of the vehicle body.

Connected via 22c, 24c (20b, 22b.

24E) indicates the connection point of the inner end of each lateral link to the vehicle body side. Connection points 20a and 22a124a of the outer ends of each lateral link to the wheel support 12 are positioned so as not to be aligned in a straight line within a vertical plane in the longitudinal direction of the vehicle body.

The shock absorber 26 is a combination of a known coil spring and a damper, and extends in the vertical direction.A lower end is attached to the wheel support 12 so as to be rotatable around a horizontal axis in the lateral direction of the vehicle body. is attached to the vehicle body side 16 so as to be rotationally deflectable.

The sub-frame 28 includes a pair of left and right vertical member portions 3o arranged substantially in the longitudinal direction of the vehicle body, a first horizontal member portion 36 that interconnects the rear ends of both class member portions, and the first horizontal member portion 3o. It is comprised of a second lateral member part 38 which is disposed further forward of the vehicle body than the member part 36 and similarly connects both class member parts to each other. The nub frame 28 may further include other member portions, or only one of the first and second lateral member portions may be provided. In short, it is sufficient to include at least a pair of left and right vertical member portions and one horizontal member portion that connects both class member portions. The subframe 28 is connected to and supported by the vehicle body, and in this embodiment, it is supported by the vehicle body through rubber bushes 30c and 3Qd at the front and rear ends of the two-class member portion 3°.

The left and right vertical member portions 30 have left and right swing arm base ends 18a to be attached to the subframe near their front ends, and left and right swing arm base ends 18a to be connected to the subframe near their rear ends. Each inner end of the lateral links 20.22.24 is connected.

Also, like that, the left and right lateral links 20, 22.24
The left and right vertical member portions to which are connected, respectively, are configured so that their natural frequencies are different from each other.

In this embodiment, by making the section modulus of the left and right vertical member parts different, the natural frequencies of both the vertical member parts are made to be different. Specifically, both line member portions 30 are connected to the upper plate material 30e as shown in FIG.
By joining the upper plate material 30e and the lower plate material 30f, and by using the upper plate material 30e and the lower plate material 30f having the same shape on the left and right but having different plate thicknesses t,
That is, the left and right vertical members have the same cross-sectional shape at corresponding locations, but are configured to have different plate thicknesses, thereby making the section modulus different, and thus the natural frequency different.

Of course, any method may be used to increase the number of unique imaging points. The coefficients may be different, or factors other than the section modulus may be used, such as changing the length of the vertical member portion or the hardness of the rubber mount that supports the vertical member portion on the left and right sides.

As described above, in the automobile rear suspension according to the present invention, since the natural frequencies of the left and right vertical members forming the subframe are different, it is possible to reduce the vibration of the subframe and the muffled noise caused by the vibration. I can do it.

Note that in the above description, words such as the vehicle body longitudinal direction, lateral direction, or horizontal direction are not limited to the vehicle body longitudinal direction in a strict sense, but also include cases where the vehicle body is generally oriented in that direction.

Furthermore, although the embodiment in which there are three lateral links has been described above, the present invention has two lateral links.
It can be suitably applied to the case of a book or to the case of a plurality of books of four or more.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an embodiment of a rear suspension for an automobile according to the present invention, and FIG. 1 is a plan view;
2 is an elevational view seen from the direction of the arrow in FIG. 1, and FIG. 3 is a sectional view taken along the line ■--■ in FIG. 10... Rear wheel 12... Wheel support 16... Heavy body side 18... Swing arm 2
0.22.24...Lateral link 28...Subframe 30...Vertical member portion 36.38...Horizontal member portion Fig. 2 Fig. 3

Claims (2)

[Claims] (1) A wheel support that rotatably supports the rear wheel,
It is arranged in the longitudinal direction of the vehicle body, the base end is attached to the vehicle body side, and the distal end is attached to the wheel support, and the distal end is swingable in the vertical direction of the vehicle body about the base end, and receives rotational force from the rear wheel. and a swing arm that receives longitudinal force, each of which is disposed in the lateral direction of the vehicle body, each outer end being connected to a mutually spaced point on the wheel support, and each inner end being connected to a mutually spaced point on the vehicle body side. A sub-frame that is supported by the vehicle body and is made up of a plurality of lateral links, at least a pair of left and right vertical members disposed approximately in the front-rear direction of the vehicle body, and a horizontal member portion that interconnects both vertical member portions, and is supported by the vehicle body. each inner end of the plurality of lateral links is connected to the left and right vertical member portions of the subframe, respectively, and the left and right vertical member portions are configured such that their natural frequencies are different from each other. Features of automobile rear suspension. (2) The natural frequencies of the left and right vertical member portions are configured to be different from each other by making the section modulus of the left and right vertical member portions different. The rear suspension of the automobile described in item 1.