JPS63258207A - Active type suspension - Google Patents

Abstract

PURPOSE:To aim at improvements in riding quality and groundability by detecting vertical acceleration of springing and unspringing, finding a command signal to damp vertical vibrations, and making each pressure control valve so as to be controlled. CONSTITUTION:When vertical vibrations are inputted via wheels 11FL-11RR, each vertical acceleration is inputted into a controller 22 from each of springing vertical acceleration sensors 26FL-26RR and unspringing vertical acceleration sensors 27FL-27RR. The controller 22 adds springing and unspringing vertical acceleration signals imposed on each wheel and operates a command signal to each pressure control value, outputting it to respective pressure control valves 20FL-20RR. With this operation, these pressure control valves 20FL-20RR output such pressure that regulated offset pressure according to each vertical vibration, thereby coping with a body position variation. With this constitution, riding quality and groundability are improvable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an active suspension device, and in particular,
Fluid pressure cylinders such as hydraulic cylinders are interposed between the vehicle body side member and each wheel side member, and pressure control allows the operating pressure of each fluid pressure cylinder to be adjusted individually according to the value of a predetermined command signal. The present invention relates to an active suspension device that is equipped with a valve and that controls the value of a command signal according to vertical acceleration acting on a vehicle.

[Prior Art] As an active type suspension device, there is, for example, the one described in Japanese Patent Application No. 134218/1988, which was previously proposed by the present applicant.

As shown in FIG. 8, this prior application has a fluid pressure cylinder 3 interposed between a vehicle body side member 1 and a wheel side member 2, and the operating pressure of this fluid pressure cylinder 3 is changed only in response to a command signal. The vertical acceleration sensor 5 detects the vertical acceleration of the sprung body almost directly above each wheel of the vehicle body, and based on this detected value, the value of the command signal is sent to the first-order delay circuit. The pressure control valve 4 is controlled by the command signal from the controller 6 included in the pressure control valve 6, thereby suppressing the vertical movement of the vehicle. Here, 3A indicates a coil spring.

As for damping the vertical vibration under the spring in this suppression control, as shown in the same figure, a damping valve 8 is provided between the fluid pressure cylinder 3 and the accumulator 7, and thereby the damping force against the unsprung vibration is was generated as shown in FIG. Also, the equivalent model in Figure 8 is shown as
It will look like Figure 10. In FIG. 10, the N damping force F for sprung vibration is F=-C2xl. In the figure, K2 is the spring constant of the coil spring, K is the longitudinal stiffness of the tire, C2 is the damping coefficient of the feedback control system, C is the damping constant by the damping valve 8, xl is the sprung mass displacement, and xl is the sprung mass. The displacement, xo, is the road surface displacement.

[Problem that the invention seeks to solve]

The damping force characteristic of unsprung vibration in the technology described in the above-mentioned earlier application is shown by curve 8 in Fig. 11, and curve C in the figure corresponds to a mechanical suspension in which a coil spring and a shock absorber are installed together. Compared to this, the peak value of the amplitude ratio (gain) between the unsprung input amplitude and the unsprung amplitude in the vicinity of the unsprung resonance frequency (for example, 10 Hz) was suppressed, and this was effective in this respect.

By the way, originally, the damping force for vertical vibration under a spring is
Although it is ideal to output according to the absolute vertical speed of the unsprung mass and provide good riding comfort, in the technology described in the prior application, similarly to the conventional mechanical suspension, the damping valve 8 Since the damping force was generated in accordance with the relative speed between the upper and lower parts, unnecessary damping force was also generated, and this resulted in an unresolved problem in that it became an excitation force on the car body and worsened the riding comfort. There was a problem.

Therefore, the present invention was made by focusing on such unresolved problems, and detects the vertical acceleration of the sprung mass and the vertical acceleration of the unsprung mass, and based on the detected values, the command signal calculation means Since a command signal calculated to damp the vertical vibration of the sprung mass is output to each pressure control valve, for example, the absolute vertical displacement speed of the sprung mass and unsprung mass can be determined by the command signal calculation means in the vicinity of the resonant frequency of the sprung mass and the sprung mass. By outputting command signals corresponding to the pressure control valves, it is possible to accurately control damping in the vertical direction of the sprung mass and unsprung mass, thereby solving the above-mentioned problems. .

[Means for solving problems]

In order to achieve the above object, the present invention includes fluid pressure cylinders separately interposed between a vehicle body side member and each wheel side member, and the operating pressure of each of the fluid pressure cylinders is set to a value of a predetermined command signal. In an active suspension device, the active suspension device is equipped with a pressure control valve that can be adjusted according to a pressure control valve, and is configured to control the value of the command signal according to a vertical acceleration acting on a vehicle, in which vertical acceleration on a spring of a vehicle is detected. a sprung mass vertical acceleration detection means, a sprung mass vertical acceleration detection means for detecting the vertical acceleration of the sprung mass of the vehicle, and an acceleration detected by the '4 yaw mass vertical acceleration detection means and the sprung mass vertical acceleration detection means; The pressure control valve is characterized by comprising a command signal calculating means for calculating a command signal corresponding to a vertical speed for damping vibrations in the vertical direction based on the pressure control valve, and supplying the command signal to each pressure control valve.

[Effect]

In this invention, the sprung mass vertical acceleration of the vehicle is detected by the sprung mass vertical acceleration detection means, the sprung mass vertical acceleration of the vehicle is detected by the sprung mass vertical acceleration detection means, and the sprung mass vertical acceleration detection means and the sprung mass vertical acceleration detection means are detected. A command signal value corresponding to the vertical speed of the vertical vibration is calculated by the command signal calculation means based on the acceleration value detected by the acceleration detection means,
This is output to each pressure control valve. Each of the pressure control valves controls the operating pressure of a fluid pressure cylinder interposed between the vehicle body side member and each wheel side member in accordance with the value of an input command signal. Therefore, by appropriately controlling the value and phase of the command signal output by the command signal calculating means, it is possible to generate an accurate damping force against the vertical vibrations of the sprung and unsprung parts of the vehicle.

〔Example〕

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

1 to 7 are diagrams showing one embodiment of the present invention.

In FIG. 1, 10 indicates a vehicle body side member, and 1IFL~
IIRR indicates the front to rear right wheels, and 12 indicates an active suspension device.

The active suspension device 12 includes front to rear right hydraulic cylinders 18FL to 18RR as fluid pressure cylinders interposed between the vehicle body side member 10 and each wheel side member 16 of the wheels 11FL to IIRR, and the hydraulic cylinders 18FL to 18RR. Cylinder 18FL
The front right pressure control valves 20FL to 20RR, each of which can adjust the operating pressure of ~18RR, and this pressure control valve 20FL~
20RR as a command signal calculating means for outputting a predetermined command signal, and a sprung ball bottom acceleration sensor 26PL as a sprung vertical acceleration detecting means for detecting the acceleration of the vertical component on the spring of the vehicle.
~26RI? , sprung ball bottom acceleration sensors 27FL to 27RR as sprung top and bottom vertical acceleration detection means for detecting the acceleration of the vertical component of the unsprung portion of the vehicle, and a pressure control valve 20
Hydraulic source 28 and hydraulic cylinder 1 for FL~20RR
Coil springs 29 are attached to each of 8FL-18RR and support the static load of the vehicle body. ..., 29. Among these, the coil springs 29° . . . , 29 have relatively low spring constants.

Each of the hydraulic cylinders 18FL-18RR has a cylinder tube 18a, and this cylinder tube 18
A is formed with a lower pressure chamber separated by a piston 18c. Then, the cylinder tube 18a is attached to the wheel side member 16, and the piston rod 18b
is attached to the vehicle body side member 10. Further, each of the lower pressure chambers is individually communicated with the input/output boats of the pressure control valves 20FL to 20RR via a partially flexible hydraulic piping 30 and an internal flow path of the cylinder rod 18b,
As a result, the working oil pressure in the lower pressure chamber is controlled, and the hydraulic cylinders 18FL to 18RR can each be driven independently.

Each of the pressure control valves 20FL to 20RR has a cylindrical valve housing 34 and a proportional solenoid 36 integrally formed therein, as shown in FIG. An insertion hole 34a is provided in the center of the spool 34, and a spool 38 with a spring 37 interposed therebetween and a rod 40 are slidably disposed in the insertion hole 34a.

Further, the valve housing 34 has a hydraulic piping 42 that has one end communicating with the insertion hole 34a and the other end connected to the hydraulic oil supply side of the hydraulic power source 28.
and an output port 34c which similarly has one end communicating with the insertion hole 34a and the other end connected to the drain side of the hydraulic power source 28 via a hydraulic piping 44,
Similarly, one end communicates with the insertion hole 34a, and the other end communicates with each of the hydraulic cylinders 18FL to 181? through the hydraulic piping 30. An input/output capo 34d communicating with the lower pressure chamber of R is formed. The output port 34c has a drain passage 3 communicating between the output port 34c and the upper and lower ends of the spool 38.
4e and 34f are formed. Further, the spool 38 is formed with a land 38a facing the input boat 34b and a land 38b facing the output port 34c.
A land 38c having a diameter smaller than that is provided. and,
A pressure control chamber C is formed between the land 38a and the land 38c, and this pressure control chamber C is connected to the input/output port 34d via the pilot passage 34g.

On the other hand, the proportional solenoid 36 controls the pressing force of the spring 37 via the rod 40, and the position of the spool 38 is
'It has a function of controlling movement between the off-cent position and the operating positions on both ends thereof.

For this purpose, the proportional solenoid 36 includes an actuator 36a that is slidable in the axial direction and an excitation coil 36b that drives the actuator 36a. The drive is controlled by a command signal V.

Here, the command signal ■ and each pressure control valve 20FL to 201?
The relationship between R and the working oil pressure P output from the input/output boat 34d is as shown in FIG.

In the figure, when the command signal V is zero, a predetermined offset pressure P0 is output, and when the command signal V increases in the positive direction from this state, the operating pressure P increases with a predetermined pressure gain α1. , saturates when the maximum output pressure P MAX of the hydraulic power source 28 is reached. Furthermore, when the command signal V increases in the negative direction, the operating pressure P decreases in proportion to this and becomes zero.

In other words, when the command signal (■) is zero, the spool 38 increases the pressure of the pressure adjustment spring 37 and the pressure of the pressure control chamber (C).
That is, the lower pressure chamber L of the hydraulic cylinders 18FL-18RR
), that is, a predetermined neutral position. Then, a predetermined offset hydraulic pressure P0 is supplied to the lower pressure chambers of the hydraulic cylinders 18FL-18RR,
The strokes of the hydraulic cylinders 18FL to 18RR are set to predetermined values.

Furthermore, when the command signal ■ increases in the positive direction, the actuator 36a
is lowered, the spool 38 is lowered accordingly, and the input/output capo 34d is communicated with the input boat 34b. Therefore, the output pressure P of each of the pressure control valves 20FL to 20RR increases, and the strokes of the hydraulic cylinders 18FL to 18RR extend.

On the other hand, when the command signal V increases in the negative direction, the actuator 36a
and the spool 38 rises, the input/output boat 34d is communicated with the output port 34c, and thereby, contrary to the above, the hydraulic cylinders 1.8FL to 18RI? The stroke of the suspension will be reduced and these will allow adjustment of the suspension stroke as required.

On the other hand, at a predetermined position on the vehicle body corresponding to approximately directly above the wheels 11FR to IIRR, the above-mentioned sprung ball under-ball acceleration sensor 2 is installed.
Each is equipped with 6FL to 26RR.

That is, in this embodiment, as shown in FIG.
Sensor 2 is installed near the FL directly above the front left vehicle 11FL.
6FR is disposed near the substantially directly above the front right wheel 11FR, the sensor 26RL is disposed near the substantially directly above the rear left wheel 11RL, and the sensor 26RR is disposed near the substantially directly above the rear right wheel 11RR. . Each of the sprung ball under-ball acceleration sensors 26FL to 26RR detects the acceleration of the vertical component on the spring at each wheel position of the vehicle, and generates an acceleration signal Gl + . . . which is an analog voltage signal corresponding to the acceleration.
Gt is output to the controller 22 separately.

Furthermore, spring stop acceleration sensors 27FL to 27RR are individually disposed at predetermined side positions of the cylinder tubes 18a of the hydraulic cylinders 18FL to 18RR. Each of these sensors 27FL to 27RR detects the acceleration of the vertical component under the spring and generates an acceleration signal (1+..., Gt) which is an analog voltage signal corresponding to the acceleration.
are output to the controller 22 separately.

Further, a controller 22 is installed at a predetermined position on the vehicle body to control the entire device, and is specifically configured as shown in FIG. 4. That is, the controller 22 is individually provided with command signal calculation units 22FL to 22RR for the front to rear right pressure control valves 20FL to 20RR. Among these, for example, the front left command signal calculating section 22FL is connected to a low-pass filter 54 that inputs the acceleration signal G1 from the front left sprung ball under-ball acceleration sensor 26FL and forms a command signal 1, and a front left unsprung ball acceleration sensor A band pass filter 56 inputs the acceleration signal G2 from the stop acceleration sensor 27FL to form the command signal 2, and outputs the command signal V obtained by adding the command signals V1 and V2 to the excitation coil 36b of the front pressure control valve 20FL. The adder 58 includes an adder 58.

Among these, the frequency transfer function H+ (jω) of the low-pass filter 54 is H+(jω)=1/(1+jω'r+)...
+1), and its gain IH
The frequency characteristics of 51 and phase φ are as shown in FIG. 5+11. That is, in a predetermined band component including the sprung mass resonant frequency (here, 1 Hz) region, the phase φ is delayed by approximately 90° with respect to the input signal after the sprung mass resonant frequency IHz. That is, the output signal of the low-pass filter 54 has a phase delay of 90 degrees with respect to the vertical acceleration input signal on the spring, and is in the same phase as the vertical velocity on the spring, and based on this output signal, the hydraulic cylinder 18
By controlling the pressure between FL and 18RR, it is possible to obtain a damping force for vertical vibration on the spring.

Further, the frequency transfer function H2(Jω) of the bandpass filter 56 is Hz(jω)=jω/((1+jωT2)・(1+
jωT, )]...(2), and the frequency characteristics of its gain IH21 and its phase φ2 are as shown in FIG. 5(2). That is, only signal components in a predetermined band including the unsprung resonant frequency (here, 10 Hz) are passed, and the phase φ2 is delayed by approximately 90° near the unsprung resonant frequency. That is,
The output signal of the band pass filter 56 has a phase delay of 90 degrees with respect to the vertical acceleration input signal of the sprung mass, and is in the same phase as the vertical velocity of the sprung mass, and based on this output signal, the pressure of the hydraulic cylinders 18FL to 18RR is By controlling this, it is possible to obtain a damping force for vertical vibration under the spring. In addition, in the above (11 (21 formula), T I"' T
3 is a time constant, and ω is an angular frequency.

On the other hand, the command signal calculating section 22Fl from the front cloth to the rear right side? ~22
RR also has the same configuration as the front left command signal calculating section 22FL described above.

By the way, if we focus on the feed hack control system for one arbitrary wheel (for example, the front left wheel 11FL) in the configuration described above, it becomes as shown in FIG. 6.

Further, an equivalent model of the control system shown in FIG. 6 can be expressed as shown in FIG. The structure shown in FIG. 7 is the same as that shown in FIG. 10 described above, with the addition of a feedback system for suppressing vertical vibration under the spring. In the figure, K2 is the spring constant of the coil spring 29, CI and C2 are the damping coefficients of the control system, and the damping force F for vertical vibration is F=-C, -C2 2...・Represented by (3).

Next, the operation of the above embodiment will be explained.

When the ignition switch (not shown) of the vehicle is turned on, the power of this device is also turned on, and its suppression control operation is started.

If the vehicle is currently stopped, there is no load movement, and the vehicle height is within the appropriate range, or if the vehicle is traveling straight at a constant speed on a flat road with no irregularities, the pitch and roll of the vehicle body should be checked. , since no rocking such as bounce occurs, the acceleration signal Gl applied to the sprung ball lower acceleration sensors 26FL to 26RR
,...l G+ and spring bottom acceleration sensor 27FL
Acceleration signal G2.~27RR. ..., G2 becomes zero.

Therefore, the command signal calculation section 2 in the controller 22
The command signals V, . Therefore, as described above, the spools 38 of the pressure control valves 20FL to 20RR each take a predetermined neutral position, and the hydraulic cylinder 1
A predetermined offset pressure P0 is supplied to the lower pressure chambers 8FL to 18RR, respectively. Therefore, at this time,
The pressing force of the pressure adjustment spring 37 and the pressure in the pressure control chamber C (that is, the pressure in the lower pressure chambers of the hydraulic cylinders 18FL to 18RR) are balanced, and the vehicle body is supported horizontally.

It is assumed that in this state, there is a vertical component vibration input from the road surface via the wheels 11FL to IIRR due to a load change or driving on an uneven road. The spring bottom stop acceleration due to this vibration input is determined by the spring bottom stop acceleration sensors 27FL to 2.
7RR, and the unsprung vertical acceleration signal G2.・
..., is output to the controller 22 as G2, and the sprung ball bottom acceleration is outputted to the sprung ball bottom acceleration sensor 26.
The spring-top ball-bottom acceleration signal Gl 1 . . . is detected by FL to 26RR.

G, and is output to the controller 22. Among these, unsprung acceleration signal G2. . . , G2 are band-pass filters 56 .
..., 56, and this filter 56, ...,
The output of 56 is sent to the adder 58 as a command signal z, . . . , V2. . . , is output to 58. In addition, the sprung ball lower acceleration signal G1. . . . 1 Gl are the low-pass filters 54 .・・・
. , 54, and this fill 54, . . .
The output of 54 is the command signal ■1. ..., ■.

as adder 58. . . , 58, respectively.

and an adder 58. ..., 58, command signal ■2
,..., ■2 and L+...+L are added separately, and command signals ■,..., ■ are calculated.

Therefore, the pressures P output from the pressure control valves 20FL to 20RR to the hydraulic cylinders 18FL to 18RR are offset by the offset pressure P0 according to the values of the command signals V, ..., ■.
The value is adjusted to a larger or smaller value, resulting in a change in the attitude of the vehicle body, that is, a change in which the hydraulic cylinders 18PL to 18RR tend to operate in the direction of extension or contraction.

An opposing biasing force is generated from hydraulic cylinders 18FL-18RR.

At this time, due to the vibration input from the road surface, the sprung ball bottom acceleration signal G1. ....

When the frequency of . ..., 54, the command signal ■1. ..., Vl is the spring-specific speed signal G3. ...
, a phase delay of about 90 degrees with respect to Gl occurs, and the phase is almost the same as the vertical velocity on the spring. Therefore, the hydraulic cylinder 18 resists the sprung mass vibration in the vicinity of the sprung mass resonance frequency.
The urging force generated by FL to 18RR has a damping effect.

In addition, due to the vibration input from the road surface, the unsprung vertical acceleration signal G2. . . , G2 is a bandpass filter 56 . ..., only the 56 pass band components pass, and near the unsprung resonance frequency (10 Hz) (see the shaded area in Fig. 5 (2)), the phase is delayed by about 90 degrees, and the vertical velocity of the unsprung component is delayed. Since the phase is the same as that of the hydraulic cylinders 18FL to 181? The biasing force generated by R has a damping effect on the vibration when the spring is lowered.

In this way, in this embodiment, the vertical displacement on the sprung mass and the unsprung mass correspond to the respective absolute velocities (or, in the case of roll and pitch, the vertical component of the displacement), and Damping force is generated only near the resonance frequency of each unsprung part. Therefore, in this example, the amplitude ratio of the vibration input to the frequency is Xl /X6 (
The characteristics of Xz: sprung mass displacement, xo: road surface displacement) are as follows:
The curve A shown in FIG. 11 described above is obtained, and the damping characteristics are extremely good not only near the sprung resonance frequency but also near the sprung resonance frequency.

In addition, in the above embodiment, the pressure control valves 20FL to 2
Although it has been explained that the response of 0RR is sufficiently high compared to the unsprung resonance frequency, suppose that the response of pressure control valves 20FL to 20
Even if the response of the RR is delayed at the unsprung resonance frequency, the low-pass filter 54. ..., 54 and bandpass filter 56° ..., 56 (or when configured with a low-pass filter and a bypass filter,
Even if the phase characteristics of these filters are shifted by that amount and the entire damping control system is set to be delayed by 90 degrees at the unsprung resonance frequency, the same effect as in the above case can be obtained.

Further, in the above embodiment, a case was explained in which a hydraulic cylinder was used as the fluid pressure cylinder, but the present invention is not necessarily limited to this, and other fluid pressure cylinders such as an air cylinder may be applied. It is.

Furthermore, in the embodiment, the sprung ball under-ball acceleration sensor 26F
L~26RR and spring bottom stop acceleration sensor 27FL~2
Although four 7RRs are provided corresponding to each wheel position, it is also possible to omit the sprung top and unsprung bottom acceleration sensors at any one of these and calculate the amount by calculation.

Furthermore, the controller 22 in the embodiment described above may be configured entirely using a microcomputer, and may be provided with each of the functions described above.

Furthermore, in the above embodiment, a case has been described in which the bounce of the vehicle in the vertical direction is suppressed, but in this configuration, lateral acceleration or longitudinal acceleration is actively detected, thereby controlling the roll or pitch of the vehicle. A suppressing configuration may be added.

〔Effect of the invention〕

As explained above, according to the present invention, the sprung upper stop acceleration and the sprung upper ball lower acceleration are detected, and the command signal calculation means damps the vertical vibration of the sprung mass and the unsprung mass based on the detected values. For example, the command signal calculation means outputs a command signal corresponding to the absolute vertical displacement speed of the sprung mass and unsprung mass near the resonant frequency of the sprung mass and unsprung mass to each pressure control valve. By outputting the output to the control valve, it is possible to effectively suppress not only the vibration on the spring but also the unsprung part, which has the advantage of improving riding comfort and grounding on rough roads. You can get the same effect.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a sectional view of a pressure control valve in this embodiment, and FIG.
Graph showing the relationship between the output pressure of the pressure control valve and the command signal in the figure, Figure 4 is a block diagram showing the controller of this embodiment, and Figure 5 (1) shows the characteristics of the low-pass filter of the controller in Figure 4. 5(2) is a Bode diagram showing the characteristics of the bandpass filter of the controller in FIG. 4; FIG. 6 is a system diagram showing the feedback control system at any wheel position of this embodiment; Fig. 7 is an equivalent model diagram of Fig. 6, Fig. 8 is a system diagram showing the feedback control system at an arbitrary wheel position according to the example described in the earlier application, and Fig. 9 is a damping force characteristic diagram by the damping valve of Fig. 8. , FIG. 10 is an equivalent model diagram of FIG. 8, and FIG. 11 is a graph showing the amplitude ratio of vibration transmission to frequency according to the present embodiment and the example described in the prior application. In the figure, 10 is a vehicle body side member, IIFL to IIRR are wheels,
12 is an active suspension device, 16 is a wheel side member,
18FL~18RR are hydraulic cylinders, 20FL~20R
R is a pressure control valve, 22 is a controller as a command signal calculation means, 26FL to 26RR are sprung top ball bottom acceleration sensors, and 27PL to 27RR are spring bottom stop acceleration sensors.

Claims (2)

[Claims] (1) Hydraulic cylinders installed separately between the vehicle body side member and each wheel side member, and pressure control that allows the operating pressure of each of these hydraulic cylinders to be adjusted according to the value of a predetermined command signal. In the active suspension device, the active suspension device is configured to control the value of the command signal according to the vertical acceleration acting on the vehicle, comprising: a sprung mass vertical acceleration detection means for detecting the vertical acceleration of the sprung mass of the vehicle; unsprung vertical acceleration detection means for detecting the vertical acceleration of the unsprung part of the vehicle; and a vertical velocity equivalent that damps vertical vibration based on the acceleration detected by the sprung vertical acceleration detection means and the unsprung vertical acceleration detection means. 1. An active suspension device comprising command signal calculation means for calculating a command signal and supplying the command signal to each pressure control valve. (2) The command signal calculation means has a low-pass filter or a band-pass filter that passes the unsprung vertical acceleration signal, and this filter converts the unsprung vertical acceleration signal into the unsprung vertical acceleration signal in the vicinity of the unsprung resonance frequency. 2. The active suspension device according to claim 1, wherein the active suspension device outputs a command signal having a phase delay of approximately 90 degrees in response characteristics up to the output pressure.