JPH02120104A - Suspention device for vehicle - Google Patents

Abstract

PURPOSE:To improve the travelling safety and the comfortability and secure the fine groundability by locating two shock absorbers having the different damping coefficient in series between the space under and above a spring and while locating a damper member for damping the oscillation of the resonance point under the spring. CONSTITUTION:A multidamper 8 extensionable in the vertical direction is located between a lower arm 3 under a spring and a body panel above the spring. And two shock absorbers 10, 11 are continuously provided in series in the multidamper 8 and while each coil spring 12, 13 is respectively located on the outer peripheral of the shock absorbers. The lower end of a piston rod 29 of the lower side shock absorber 11 is connected to the lower arm 3 through a liquid bush 30. And the liquid bush 30 is formed so as to generate the damping force to the oscillation with the flow resistance generated at the time when the liquid passes through a throttle, and thereby, it functions as a damper member for damping the oscillation of the resonance point under the spring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension device for a vehicle, and particularly relates to a suspension device in which two or more shock absorbers are arranged in series between an unsprung portion and an unsprung portion. .

(Prior Art) Generally, in a vehicle suspension system, one shock absorber is disposed together with a spring between an unsprung part (wheel side) and an unsprung part (vehicle body side) in order to suppress wheel vibration. ing. The damping force of this shock absorber is determined in the range of low vibration frequencies, that is, in the range of vibration frequencies generated by driver operations (2 to 3H).
In order to improve driving stability and ride comfort, it is recommended to increase the vibration frequency (below 5 Hz) and reduce it in the high vibration frequency range, that is, the vibration frequency range that is not based on driver operation but is caused by road surface stimulation (approximately 5 Hz or higher). This is considered desirable in order to improve together.

For this reason, a variable damping force type shock absorber has conventionally been used as the above-mentioned shock absorber, but this variable damping force type shock absorber has a complicated configuration of the control section, etc., and is expensive 61H. In addition to this, there is also the problem of lack of responsiveness.

On the other hand, conventionally, for example, Utility Model Application No. 62-103713
As disclosed in the publication, there are two
A damper is known in which two shock absorbers are arranged in series and a coil spring is arranged around the outer periphery of each shock absorber (hereinafter, this type of damper is referred to as a multi-damper). In the case of this multi-damper, by setting the damping coefficients of the two shock absorbers to be different, the damping force can be changed to two values, upper and lower, depending on the vibration frequency, similar to a shock absorber with a variable damping force type. In the example of the publication, one shock absorber is of a variable damping force type.

(Problem to be Solved by the Invention) Incidentally, in the conventional multi-damper described above, the damping force is uniformly reduced in the high vibration frequency region, but even in the high frequency vibration region, the unsprung resonance point (10 to 15H
If the vibration is not suppressed with a large damping force, there is a risk that the wheel will bounce off the road surface significantly.

The present invention has been made in view of this point, and its object is to improve the above-mentioned multi-damper so as to effectively suppress vibrations at the unsprung resonance point.
This is to prevent wheel bouncing.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention connects in series at least two shock absorbers having different damping coefficients F[] between the unsprung portion and the unsprung portion. The structure includes a damper member that damps vibrations at the unsprung resonance point.

(Function) With the above configuration, in the present invention, a multi-damper formed by connecting two or more shock absorbers in series generates a damping force according to the vibration frequency, and also suppresses vibration at the unsprung resonance point. As a result, the damper member will perform a damping function.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 and 2 show a vehicle suspension system according to an embodiment of the present invention. In FIG. 1, 1 is a wheel support member that rotatably supports a wheel (not shown), and 2 and 3 are an upper arm and a lower arm each consisting of an A-shaped arm arranged in the vehicle width direction, both arms. 2
, 3 are connected to and supported by a cross member 4, which is a strength member of the vehicle body, via brackets 5a, 5b, etc. so as to be able to swing up and down, while their outer ends are attached to the upper or lower part of the wheel support member 1. are connected to each other via ball joints 6.7.

Reference numeral 8 denotes a multi-damper extending downward on the road between the unsprung lower arm 3 and the sprung body panel 9, and the multi-damper 8 has two shock absorbers 10 and 11 connected in series. The shock absorbers 10 and 11 are connected to each other, and coil springs 12 and 13 are arranged around the outer periphery of each shock absorber 10 and 11, respectively.

The above multi-damper 8 or shock absorber 10,
The structure of No. 11 is shown in detail in FIG. That is, the two shock absorbers 10.11 have their tubes 21.22
They are connected by joining them together. In addition, each tube 21
．． Pistons 23 and 24 having throttle holes 23a and 24a are slidably inserted into the tubes 22, respectively, and the pistons 23 and 24 are slidably inserted into the outer wall of each tube 21 and 22 (described later). piston rod 27,
Gas chamber 25 that allows volume changes due to vertical movement of gas chamber 29
．． 26 is formed.

One end (lower end) of a piston rod 27 is connected to the piston 23 of the upper shock absorber 10, and the other end (upper end) of the piston rod 27 is connected to the tube 2.
1 and is attached to the vehicle body panel 9 via a rubber mount 28. On the other hand, the piston rod 29 is attached to the piston 24 of the lower shock absorber 11.
One end (upper end) of the piston rod 29 is connected to the piston rod 29.
The other end (lower end) extends below the tube 22 and is connected to the lower arm 3 via a liquid bushing 3o. Each of the piston rods 27 and 29 has a throttle hole 2 in a portion adjacent to the piston 23 or 24, respectively.
Adjustment springs 18 and 19 are installed to adjust the damping resistance or damping force of each shock absorber 10, 11 depending on the aperture ratio of 3a or 24a. Here, the two upper and lower shock absorbers 10.11 are provided so that their damping resistances are different, and in the case of this embodiment, the damping coefficient of the upper shock absorber 10 is the damping coefficient of the lower shock absorber 11. It is set higher than the coefficient.

As shown in FIG. 3, the liquid bushing 30 has an outer cylinder 41 fixed to the lower end of the piston rod 29 of the shock absorber 11, and is arranged concentrically with the outer cylinder 41. an inner cylinder 43 connected via;
It has a rubber 44 that is filled and fixed between the outer cylinder 41 and the inner cylinder 43. In the rubber 44, liquid chambers 45a and 45b each containing a liquid such as oil are formed on the axial extension line of the piston rod 29 on both sides of the inner cylinder 43, and both liquid chambers 45a.

Aperture hole 46 that communicates between 45b. ... is formed. When the liquid in the liquid chambers 45a, 45b vibrates at a predetermined frequency, the liquid flows through the aperture hole 46. It is designed to flow through... At this time, the flow resistance generates a damping force against the vibration, and the vibration frequency during the flow is set to approximately match the unsprung resonance point, so that the liquid pusher 30 is at the unsprung resonance point. It functions as a damper member that dampens vibrations at points.

Further, the upper end of the piston rod 27 of the upper shock absorber 10 is provided with a tube 2 relative to the piston rod 27 when the shock absorber 10 contracts.
A stopper rubber 31 that restricts the upward movement of the coil spring 12 and a first spring seat 33 that supports the upper end of the coil spring 12 via the rubber seat 32 are installed, while the piston rod of the lower shock absorber 11 At the lower end of the coil spring 29, there is a stopper rubber 34 that restricts the contraction movement of the shock absorber 11 (that is, upward movement of the piston 24 or piston rod 29 with respect to the tube 22), and a stopper rubber 34 that supports the lower end of the coil spring 13 via a rubber sheet 35. A second spring seat 36 is attached.

In addition, the tubes 21 of both shock absorbers 10 and 11,
A third spring seat 37 is located near the joint between the two.
The lower end of the coil spring 12 and the upper end of the coil spring 13 are supported by the spring seat 37 via a rubber seat 38 or 39, respectively.

Next, to explain the operation and effect of the above embodiment, when the vibration frequency is low that is generated from the vehicle body side based on the driver's operation when driving on a mountain road etc., the two shock absorbers constituting the multi-damper 8 10.11, the pistons 23 and 24 slide and reciprocate within the tubes 21 and 22 as the vehicle body vibrates, and the tubes 21 and 22
The fluid (oil, etc.) inside the piston 23, 24's throttle hole 2
By flowing through 3a and 24a, a damper function (vibration damping function) is exerted due to the flow resistance at the throttle holes 23a and 24a, thereby obtaining a large damping force.

On the other hand, when there is a high vibration frequency (for example, road noise) generated from the wheel side, such as when driving straight, the upper shock absorber 10 of the two shock absorbers configuring the multi-damper 8 Since the resistance is large, that is, the throttle rate of the throttle hole 23a of the piston 23 is set to be large, the fluid in the tube 21 cannot flow through the throttle hole 23a, and the damper function is no longer exhibited. Therefore, the lower shock absorber 11 only exerts a small damping force.

In addition, in the area where the vibration frequency is high, especially near the unsprung resonance point, the lower end of the multi-damper 2 and the lower arm 3
The liquid bush 30 interposed at the connecting portion with the liquid chambers 45a and 45b allows the fluid in the liquid chambers 45a and 45b to flow through the throttle holes 46. . . , and exerts a relatively large damping force due to the flow resistance at the throttle holes 46, . In addition, fluid bushing 30
The relationship between damping force and vibration frequency is shown in Figure 4.

Therefore, as shown in Figure 5, the damping force against vibration exerted by the entire suspension system is basically large in the low vibration frequency range and small in the high vibration frequency range, so it is effective when driving on rough roads. It is possible to improve both running stability and ride comfort when driving on good roads, and because a large damping force is obtained at the unsprung resonance point, it suppresses wheel bouncing and improves ground contact. Can be maintained in good condition.

It should be noted that the present invention is not limited to the above embodiments, but includes various other modifications.

For example, in the above embodiment, the liquid bushing 30 is used as a damper member for damping the vibration at the unsprung resonance point.
Of course, instead of this liquid bushing 30, a so-called dynamic damper or the like having a mass body supported by a spring member may be used.

In addition, in the above embodiment, the multi-damper disposed between the unsprung portion and the unsprung portion is configured by connecting two shock absorbers with different damping coefficients in series, but in some cases, three or more shock absorbers may be connected in series. Shock absorbers may be connected in series.

(Effects of the Invention) As described above, according to the vehicle suspension device of the present invention, two or more shock absorbers arranged in series between the unsprung portion and the unsprung portion reduce the vibration damping force to the magnitude of the vibration frequency. It is possible to improve running stability and ride comfort by changing the damper member according to the amount of vibration, and the damper member can exert a large damping force at the unsprung resonance point, so that good ground contact can be ensured.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially cutaway front view showing the overall structure of the suspension device, Fig. 2 is a vertical side view of the multi-damper, and Fig. 3 is a liquid FIG. 4 is a longitudinal cross-sectional view of the bushing, FIG. 4 is a damping force characteristic diagram of the liquid bushing, and FIG. 5 is a damping force characteristic diagram of the entire suspension device. 3...Lower arm (under spring), 9...Vehicle body panel (
sprung), 10.11...shock absorber 3C=
7? +-; b Figure 1 Figure 2

Claims (1)

[Claims] (1) At least two shock absorbers with mutually different damping coefficients are arranged in series between the unsprung portion and the unsprung portion, and a damper member is provided to damp vibrations at the unsprung resonance point. Suspension equipment for vehicles.