JPH0542812A - Suspension of vehicle - Google Patents

Abstract

PURPOSE:To reduce the transmittivity of vibration near an unspring resonance point decided by a frequency depending type shock absorber. CONSTITUTION:A suspension has a frequency depending type shock absorber 4 which is interposed together with a suspension spring 3 between spring mass 1 and unspring mass 2 and whose damping coefficient changes according to vibration frequencies, an acceleration detection means 6 for detecting the vibration acceleration of the unspring mass 2, and a controller 8 which performs arithmetic arithmetic processing of the vibration acceleration detected by the acceleration detection means 6 and outputs a target control force command for restraining vibration of the unspring mass 2. When a control force generating means 7 receives the target control force command from the controller 8, the unspring mass 2 is acted upon by a control force corresponding to the command.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system having a frequency-dependent shock absorber whose damping coefficient changes in accordance with the vibration frequency.

[0002]

2. Description of the Related Art A conventional vehicle suspension system is shown in FIG. 9 by modeling a vibration system for one wheel.

That is, 1 is a sprung mass corresponding to the vehicle body, 2
Is an unsprung mass corresponding to the tire, 3 is a suspension spring which is interposed between the unsprung mass 1 and unsprung mass 2, and 4 is a suspension spring which supports the unsprung mass 1 and is similarly provided Shock absorber having action, 5 is unsprung mass 2
Is a spring of a tire provided between the road surface and the road surface.

In such a model, a shock absorber of a frequency-dependent system having a characteristic that the damping coefficient, which is the ratio of the damping force and the vibration velocity, changes according to the vibration frequency as shown by the solid line in FIG. When used, the frequency characteristic of the vibration transmissibility transmitted from the road surface to the sprung mass 1 is as shown by the solid line in FIG.

On the other hand, the characteristic of the conventional shock absorber whose damping coefficient does not have vibration frequency dependence is shown in FIG.
0 and the broken line in FIG.

By the way, in FIG. 11, the intermediate frequency range between the sprung resonance point and the unsprung resonance point is a region where humans easily feel vibration, and the lower the vibration transmissibility in this region, the better the riding comfort. Further, it is said that the lower the vibration transmissibility near the unsprung resonance point, the better the ground contact of the tire and the better the steering stability.

Therefore, comparing the frequency-dependent shock absorber with the conventional vibration transmissibility, the frequency-dependent shock absorber is lower in the intermediate frequency range and has a better riding comfort, whereas the unsprung resonance point is near. On the contrary, it is higher than the conventional shock absorber, and the ground contact of the tire is reduced.

[0008]

Since the conventional frequency dependent shock absorber is constructed as described above, the vibration transmissibility near the unsprung resonance point is high, so that the ground contact property of the tire with respect to the road surface is deteriorated. In addition, there is a serious problem that the steering stability is inferior to the conventional shock absorber.

The present invention has been made by paying attention to the above-mentioned conventional problems, and lowers the vibration transmissibility in the vicinity of the unsprung resonance point by the frequency-dependent shock absorber to reduce the ground contact and An object of the present invention is to provide a suspension system for a vehicle that can ensure sufficient driving safety.

[0010]

SUMMARY OF THE INVENTION A vehicle suspension system according to the present invention is a frequency-dependent shock in which a damping coefficient is interposed between an unsprung mass and an unsprung mass together with a suspension spring so that the damping coefficient changes according to the vibration frequency. An absorber, an acceleration detecting means for detecting the vibration acceleration of the unsprung mass, and a vibration acceleration detected by the acceleration detecting means are arithmetically processed to output a target control force command for suppressing the vibration of the unsprung mass. The control force generating means receives a target control force command from the controller and causes the control force corresponding thereto to act on the unsprung mass.

[0011]

In the controller according to the present invention, the target control force command for suppressing the vibration of the unsprung mass is obtained based on the vibration acceleration detected by the acceleration detecting means, and the control force generating means applies the predetermined control force in accordance with this command. It acts on the unsprung mass and functions to reduce the vibration transmissibility near the unsprung resonance point.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a basic configuration diagram showing a vehicle suspension system of the present invention, which is shown in correspondence with the model diagram of FIG.

In FIG. 1, 1 is an unsprung mass corresponding to a vehicle body, 2 is an unsprung mass corresponding to a tire, and 3 is interposed between these unsprung masses 1 and 2,
Suspension springs 4 supporting the unsprung mass 1 are similarly provided shock absorbers having a damping action, and 5 are tire springs provided between the unsprung mass 2 and the road surface.

6 is an acceleration detecting means provided on the unsprung mass 2 for detecting vertical vibration acceleration of the spring mass, and 7 is a control force generating means for generating a control force F to the unsprung mass. It is provided in 2.

Reference numeral 8 denotes a controller, which is a controller for calculating the vertical vibration acceleration detected by the acceleration detecting means and outputting a target control force command to the control force generating means.

Here, the control force generating means 7 is one having sufficient force and responsiveness to control the vibration of the unsprung mass 2, and an electromagnetic actuator, a hydraulic actuator or the like is used.

The control force generating means 7 may be directly mounted on the suspension arm 9 which is a part of the unsprung mass 2 as shown in FIG. 2, or may be mounted on the frequency dependent shock absorber 4. Good.

FIG. 3 is a block diagram of the controller 8 in which 11 to 13 are integrators, 14 to 16 are amplifiers, and 17 is an amplifier.
Is an adder, 18 is a current amplifier, the amplifier 14 directly amplifies the vibration acceleration signal X which is the acceleration signal of the acceleration detecting means 6 and inputs the amplified vibration acceleration signal X to the adder 17, and the amplifier 15 integrates the vibration acceleration signal X into a vibration velocity. The output X1 is multiplied by a control constant, then amplified and input to the adder 17, and the amplifier 16 multiplies the vibration displacement signal X2 in which the vibration acceleration is doubly integrated by the control constant, and then amplified and supplied to the adder 17. Output.

The output of the current amplifier 18 is supplied to a coil described later in the control force generating means 7.

FIG. 4 is a sectional view showing the details of the control force generating means 7. In the figure, reference numeral 21 is a non-magnetic body, and a non-magnetic movable element 23 is housed in the body 21 via a bearing 22 so as to be movable up and down.

Reference numeral 24 denotes a cylindrical coil wound around a large diameter surface above the mover 23, 25 denotes a cylindrical permanent magnet provided outside the coil 24 with an annular gap, and 26 denotes a permanent magnet. 25 is a cap for caulking and fixing it in the body 21, 27 and 28 are coil springs for supporting the mover 23 from above and below so as to be positioned in the middle, and 29 is a central portion of the cap 26 through the grommet 30. A wire harness that electrically connects the lead wire 31 of the coil 24 to the output terminal of the current amplifier 18. 32 is a bolt for fixing the body 21 to the unsprung mass 2.

The operation will be described. First, when the road surface becomes uneven while the vehicle is running, the unsprung mass 2 and the unsprung mass 1 vibrate.

The sprung mass 1 is damped by the damping force generated by the frequency-dependent shock absorber 4, and the unsprung mass 2 is the damping force generated by the shock absorber 4 and the control force generated by the control force generating means 7. Controlled by.

The control force generating means 7 responds to a target control force command for constantly suppressing the vibration of the unsprung mass 2 calculated by the controller 8 based on the vertical vibration acceleration detected by the acceleration detecting means 6. Generates control power.

As a result, as shown by the solid line of the frequency characteristic of the vibration transmissibility in FIG. 5, the shock absorber 4 is used in the intermediate frequency range, and the control force generating means 7 is used in the vicinity of the unsprung resonance point and higher frequencies. The vibration transmissibility is lower than that of the conventional shock absorber shown by the broken line. As a result, both the riding comfort and the ground contact property of the tire are improved.

Next, the operation of the controller 8 and the control force generation means 7 will be described. First, the vibration acceleration signal X output from the acceleration detection means 6 is input to the adder 17 via the amplifier 14, and the vibration is also generated. A vibration velocity signal X1 obtained by integrating the acceleration signal X and a vibration displacement signal X2 obtained by double integrating the vibration acceleration signal X are input to an adder 17 via amplifiers 15 and 16, respectively.

In the adder 17, each of these signals X, X1,
A target control command is generated by X2, and this is input to the coil 24 of the control force generating means 7 as a coil current through the current amplifier 18.

On the other hand, the permanent magnet 25 has an N-shaped cylindrical inner surface.
The pole and the outer surface are S poles, and the lines of magnetic force are directed from the inner surface toward the coil 24 and return to the outer surface, as shown in FIG.

At this time, when a current flows in the coil 24 in the front direction from the paper surface in the figure, a force F is generated in the direction indicated by the arrow. The magnitude of this force F is determined by the product of the magnitude of the current, the magnitude of the magnetic flux density in the annular gap portion, and the length of the coil 24. That is, the force is proportional to the coil current.

The direction of the force F differs depending on the direction of the current flowing through the coil 24. When the current flows in the direction of the paper surface from the front in the figure, the direction of the force F is opposite to the direction of the arrow.

Therefore, a force F corresponding to the coil current is applied to the mover 23, and as a reaction force thereof, a force F opposite to the force applied to the mover 23 from the body 21 to the unsprung mass 2 is applied.
Is added.

FIG. 8 is a model of the control force generating means 7 and the unsprung vibration system at this time. Here, f is a spring force applied to the unsprung mass 2 (change amount from the balance position), and this model can be replaced with the model in FIG. 9.

According to this, the control force F corresponding to the vibration of the unsprung mass 2 is applied to the mover 23, and the force F acts on the unsprung mass 2 as a reaction force thereof.

The movable member 23 has an acceleration (F / movable member 2
(3 mass) is generated and displaced in the direction of the force F, and the spring force 2f corresponding to the displacement acts on the mover 23 and the unsprung mass 2.

Further, it has been confirmed from the desktop calculation that the maximum value of the control force is 32 kgf when the road surface input displacement is 10 mm.

Therefore, the size of the control force generating means 7 which is an electromagnetic actuator for generating such a control force can be set to, for example, about 150 × 150 × 150 mm.

As a result, the force F in the opposite direction complements the vibration damping action of the shock absorber 4 near the unsprung resonance point, and the grounding property of the tire on the road surface and the steering safety are ensured.

In this case, when the polarity of the permanent magnet 25 is opposite to the above, if the direction of the current flowing through the coil 24 is also reversed, the magnitude and direction of the force F will not change, The same effect as the above embodiment can be obtained.

[0039]

As described above, according to the present invention, a frequency-dependent shock absorber, which is interposed between an unsprung mass and an unsprung mass together with a suspension spring, has a damping coefficient that changes according to a vibration frequency. An acceleration detecting means for detecting a vibration acceleration of the unsprung mass; and a controller for calculating a vibration acceleration detected by the acceleration detecting means to output a target control force command for suppressing the vibration of the unsprung mass. Since the control force generating means receives the target control force command from the controller and causes the corresponding control force to act on the unsprung mass, vibration above the sprung resonance point or higher is generated. In the frequency range, it is possible to lower the vibration transmissibility compared to the case where a conventional frequency-dependent shock absorber is used. Therefore, the ride comfort of the vehicle and the road surface of the tire can be reduced. That can be improved grounding property, which can result in improved steering stability is the effect obtained.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing a vehicle suspension device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a mounting structure of control force generating means in the present invention.

FIG. 3 is a block diagram showing a controller according to the present invention.

FIG. 4 is a sectional view showing a specific structure of the control force generating means in the present invention.

FIG. 5 is a characteristic diagram showing vibration transmissibility characteristics according to the present invention.

6 is an explanatory diagram showing a relationship between a permanent magnet and a coil in FIG.

FIG. 7 is a configuration diagram modeling the control force generating means and the unsprung vibration system of the present invention.

8 is a configuration diagram in which the model of FIG. 7 is rewritten into a basic form of a dynamic vibration absorber type active damper.

FIG. 9 is a configuration diagram showing a model of a conventional vehicle suspension device.

FIG. 10 is a characteristic diagram showing a damping coefficient by a conventional shock absorber.

FIG. 11 is a characteristic diagram showing a vibration transmissibility by a conventional shock absorber.

[Explanation of symbols]

 1 sprung mass 2 unsprung mass 3 suspension spring 4 frequency dependent shock absorber 6 acceleration detector 7 control force generating means 8 controller

Claims (1)

[Claims] 1. A frequency-dependent shock absorber that is interposed between an unsprung mass and an unsprung mass together with a suspension spring, and has a damping coefficient that changes according to the vibration frequency, and an acceleration that detects the vibration acceleration of the unsprung mass. The detection means and the vibration acceleration detected by the acceleration detection means are arithmetically processed,
A controller that outputs a target control force command for suppressing the vibration of the unsprung mass, and a control force generation that receives a target control force command from the controller and applies a corresponding control force to the unsprung mass. And a suspension system for the vehicle including the means.