JPH03182827A - Active suspension for vehicle - Google Patents

Abstract

PURPOSE:To reduce the input oscillation effectively with the work of a changeable orifice means at the time of input of the high frequency oscillation by connecting an accumulator to an oil pressure chamber of an actuator arranged between a spring upper member and a spring lower member of a vehicle through the changeable orifice means. CONSTITUTION:An accumulator 11 for holding the line pressure is connected to the downstream side of a check valve 10 of a supply oil passage 4 connected to the discharge side of an oil pump 1, and furthermore, a suspension unit 12 is connected to the downstream side thereof through a control valve 17. The suspension unit 12 consists of a spring 13 and a hydraulic actuator 14 provided in parallel to each other between a car body 17 and a wheel 8. An accumulator 20 is connected to an oil passage 16 communicating with an oil pressure chamber 15 of the hydraulic actuator 14 through a first orifice 19, and while a second orifice 21 is provided in parallel to the first orifice 19 through a switching valve 22 between the accumulator 20 and the oil passage 16, and the switching valve 22 is opened and closed to change the oscillation reduction characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in active suspensions for vehicles used in vehicles such as automobiles.

(Prior Art) A vehicle active suspension disclosed in, for example, Japanese Unexamined Patent Publication No. 63-8009 is known.

This conventional example absorbs relatively low-frequency car body vibrations by operating a pressure control valve interposed between the hydraulic power source and the hydraulic cylinder, while also absorbing an accumulator into the hydraulic chamber of the hydraulic cylinder via a throttle valve. In connection with this, relatively high-frequency vibrations are absorbed by attenuating pressure fluctuations in the hydraulic chamber of the hydraulic cylinder using the throttle valve. In other words, the pressure control valve has a limited frequency response, so even if the pressure control valve is controlled to relatively high frequency vibrations, sufficient vibration absorption cannot be achieved. It is designed to dampen vibrations through the action of

(Problem to be Solved by the Invention) However, as in the conventional example described in -1, high-frequency vibrations are damped by the action of the throttle valve P interposed between the hydraulic chamber of the oil-sweat cylinder, the accelerator, and the rake. In other words, it is necessary to set the damping force small in order to efficiently absorb high-frequency vibrations. In order to set the damping force small, the diameter of the throttle valve must be set relatively large.
When the diameter of the throttle valve is set large, the hydraulic oil supplied to and discharged from the hydraulic cylinder by the pressure control valve becomes more likely to act on the inside of the accutake via the throttle valve. This means that the symbol of the hydraulic fluid passing through the throttle valve increases during control by the pressure control valve, so in order to ensure reliable control against vibrations in a relatively low frequency range, it is necessary to There is a problem that requires a control valve 1. In other words, setting the diameter of the throttle valve large as described above causes a decrease in the response of the γ-quadulator side. In order to solve this problem, In this case, a fast-flowing control valve must be used, which causes high costs, and a hydraulic pump with a large flow rate is also required.
It also causes increased power loss.

(Means for Solving the Problems) The present invention has been devised in view of the above-mentioned points, and is arranged between the spring parts I and the unsprung members of a vehicle to control the supply and discharge of hydraulic oil. an actuator provided to displace the unsprung member in the direction of the vehicle 1"F in accordance with the above-mentioned pressure; a control valve provided to control the supply and discharge of hydraulic fluid to the actuator; The accelerator and rake connected to the chamber, the nJ variable J refit means interposed between the accelerator and the rake and the extraction chamber, and vibration input detection for detecting the state of vibration input to the vehicle body. and a control means for controlling the state of the variable orifice means described in G. , when the detection signal of the vibration input detecting means corresponds to a high-frequency road surface, the orifice diameter of the L. This is an active suspension for vehicles that is characterized by:

(Function) According to the present invention, when the detection signal of the vibration input detection means corresponds to a high-frequency road surface, the hydraulic pressure of the Aki 31 rake and actuator is higher than when the detection signal corresponds to a high-frequency road surface. Since the orifice diameter of the variable refice means interposed between the control valve and the control valve is increased or In contrast, the variable orifice means generates a small damping force (1
1, and can softly damp the vibrations of the corpuscle.

In addition, for low-frequency vibration input, a significant vibration absorption effect can be obtained by the action of the actuator controlled by the control valve that operates according to the detection output of the lower stage of vibration input detection, and at this time, the variable orifice diameter This is possible because the orifice diameter of the stage is small.

(Example) Hereinafter, an example of the present invention will be described in detail based on the attached figures.

Figure 1 shows the system configuration of this embodiment.
In the figure, a mail pump 1 is provided to suck oil stored in a reserve tank 3 through an oil passage 2 and discharge the oil to a supply oil passage 4. An oil filter 9 and a check valve 10 are interposed in the supply oil passage 4, and the check valve 10 prohibits the oil from flowing from the downstream side to the upstream side. Akiem 1 node 11 for maintaining line pressure is downstream of check valve 10 of supply agent 1 path 4.
is connected, and on the downstream side of the accutator 11,
A suspension unit 12 is connected. 1st
1mL:! Although one suspension unit 12 is shown as a representative, a gas ventilation unit I2 is provided for each wheel, and each suspension unit is provided with a discharge oil passage communicating with the reservoir tank 3. 6 is also connected.

Each suspension unit 12 has the same 4Yf&, and a suspension spring 13 and a single-acting hydraulic actuator 14 are provided between the vehicle body 7 and the wheels 8, and a hydraulic chamber of the hydraulic actuator 14 is provided. Supply and discharge of hydraulic pressure to and from the hydraulic chamber 15 of the hydraulic actuator 14 is controlled by a control valve 17 interposed between an oil passage 16 communicating with the supply oil v64 and the discharge oil passage 6. . The control valve 17 controls the pressure acting on the hydraulic actuator 14 by controlling the flow rate of oil flowing out from the supply oil path 4 side to the discharge oil path 6 side,
The valve opening degree is controlled according to the supplied current value. Therefore, this control valve 17 can control the pressure horn in the hydraulic actuator 14 in proportion to the supplied current value, and the larger the supplied current value, the greater the supporting force generated by the hydraulic actuator 14. It is expected to increase.

Further, an oil passage 15 that communicates with the hydraulic chamber of the hydraulic actuator 14 is connected to an axle 51 and a rotor 20 via a first orifice 19, and the first orifice 19 exhibits a vibration damping effect, and the accumulator 20 Gas is sealed inside to create a gas spring effect. Furthermore, a second orifice 21 is provided between the accumulator 20 and the oil passage 15 in parallel with the first orifice 19, and a switching valve 22 is provided between the second orifice 2I and the accumulator 20. , which switches communication and cutoff between the second orifice 21 and the accumulator 20. And these first orifices 19. Second orifice 21 and switching valve 22
constitutes variable orifice means, and the second orifice 21 has a larger orifice diameter than the first orifice 19. In addition, the switching knob 22
is normally off and in the cut-off state shown.

The operation of the control valve 17 and the switching valve 22 is controlled by a controller 30 comprised of a microcomputer. This controller 30 includes a detection output of a sprung G sensor 31 that detects the vertical acceleration acting on the vehicle body corresponding to each wheel, and a vehicle height sensor 32 that is provided for each wheel and detects the stroke amount of the wheel.
The detection output of the preview sensor 33 for detecting the presence of a protrusion on the road surface in front of the vehicle, and the detection output of the vehicle speed sensor 28 for detecting the traveling speed of the vehicle are input. The controller 30 controls the operating states of each control valve 17 and each switching valve 22 for each wheel based on the detection outputs of these sensors.

This controller 30 has a configuration corresponding to a control means.

As the preview sensor 33, an ultrasonic sensor arranged at the front of the vehicle body and tilted downward is used, and the sprung G sensor 31. Vehicle height sensor 32. The preview sensor 33 serves as vibration input detection means.

. The control operations for control valve 17 performed within controller 30 are represented by the control block diagram shown in FIG. That is, the output of the sprung G sensor 31 is
The output of the vehicle height sensor 32 is differentiated by a differentiator 37 and then multiplied by KP by an amplifier 38. and amplifier 36.38
The output of the adder 39 is input to the adder 39 and added to the control amount for vehicle height maintenance stored or calculated in the controller 30, and the output of the adder 39 is output to the control valve 17 via the valve drive section 40. The operation of the control valve 17 is controlled, whereby the hydraulic actuator 14 expands and contracts to absorb input vibrations, thereby providing a soft ride.

On the other hand, the control operation of the switching valve 22 performed within the controller 30 is represented by the control flowchart shown in FIG.

To explain the flowchart shown in Figure 3,
First, in step S1, the fluctuation frequency of the output of the vehicle height sensor 32 is calculated, and in the following step 2, it is determined whether or not the calculated fluctuation frequency corresponds to a high-frequency road surface, and it is determined that it corresponds to a high-frequency road surface. If so, the process advances to step S3, where the switching valve 22 is turned on, and then the process returns.

Furthermore, when it is determined in step S2 that the fluctuating frequency does not correspond to a high-frequency road surface, the process proceeds to step S4, and based on the output of the preview sensor 33), it is determined whether or not there is a protrusion or step on the road surface in front of the vehicle. is determined. If it is determined in step S4 that there is no protrusion or step, the process returns after the switching valve 22 is turned off in step S5.

On the other hand, if it is determined in step S4 that there is a protrusion or step, the process proceeds to step S5, where the time required for the wheel to reach the protrusion or step is calculated. This time is
! As shown in Figure 54, the distance between the protrusion or step on the road in front of the vehicle and the wheels (I5 for the front wheels, L+j for the rear wheels)) and the vehicle speed V detected from the vehicle speed sensor 34.
It is calculated from . In this case, if the preview sensor 33 detects the presence or absence of a protrusion or step at a predetermined distance when the vehicle body is opened, the above 1. The value will be a fixed value, and if the distance to the protrusion or step can be detected, the above method will be used.
It becomes i.

After the time required for the wheel to reach the protrusion or step is calculated in step S6, the process proceeds to step S7, where it is determined whether or not the time calculated in step S fi has elapsed. In this case, this determination is repeated, and when the time comes for the wheel to reach a protrusion or step, the process proceeds to step S81.In step S8, the switching valve 22 is turned on for a predetermined time f, and the second orifice 21 and the :, and the l/r 20 are communicated via the switching valve 22, and after the predetermined time t has elapsed, the switching valve 22 is opened.
returns to the off state, and then the beam is turned.

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

The driving road surface is normal and not a high-frequency road! 14 (a state in which the above-mentioned fluctuating frequency is smaller than a predetermined value and no protrusion or step is detected), the 1 switching valve 22 becomes main and the communication with the second orifice 21 and the accumulator 2o is cut off, as described above. ing.

In this state, the pressure in the h11 pressure actuator 14 is controlled by the control valve 17 driven by the controller 3o, and the vibration input to the wheels 8 by the operation of the hydraulic actuator 14 is absorbed, improving the riding comfort.

In this state, the accumulator 20 and the hydraulic actuator 14 are communicated only through the first orifice with a small orifice diameter, so the operating hh flow is controlled by the control valve 17 and flows through the oil passage 19, passing through the first orifice 19. Even if the control valve 17 has a relatively small flow rate, sufficient control can be achieved.

By the way, the above-described vibration absorbing effect obtained by controlling the operation of the control valve 17 cannot be sufficiently effective against high-frequency vibrations. This is due to the fact that there is a limit to the frequency response of the control valve 17, as shown in FIG. It cannot be activated.

Therefore, in the above embodiment, the high frequency vibration is
! "zA-lator 20 (gas spring). This is due to the -L of the wheel 8 due to road surface input.
This is intended to attenuate the pressure fluctuation in the pressure chamber 15 of the extraction pressure actuator 14 due to the downward movement by the flow resistance of the orifice, but if only the first orifice 19 and the accumulator 2o are used for rg, The solid line shows Ji for pressure fluctuations in the pressure chamber 15 due to road surface input.
The force transmitted to the i-body increases as the frequency increases, so when high-frequency hole input vibrations such as when riding over a protrusion are input, particularly large vibrations are transmitted to the -di body, causing damage to the occupants. This will give a great feeling of pushing up. For this reason, the two-legged embodiment uses a configuration in which a second orifice 21 is provided in parallel with the first orifice 19.
By controlling the operation of the switching valve 22, the effect of the second orifice 21 is controlled.

That is, in the above embodiment, when the fluctuation frequency of the vehicle height sensor output is equal to or higher than a predetermined value (when high-frequency vibrations are continuously input), the switching valve is turned on, and when driving over a bump ( When a high frequency vibration is input sporadically), the switching valve 22 is turned on for a predetermined time t.

Then, by turning on the switching valve 22, the second orifice is opened, and since the orifice diameter of the second orifice 21 is larger than the first orifice 19, the substantial The orifice diameter increases greatly. As a result, the damping force against high-frequency vibrations is significantly reduced, and as shown in FIG. 6, the vibration transmission force to the vehicle body is also reduced, so that high-frequency vibration input can be efficiently damped.

In particular, when going over a bump, the feeling of pushing up can be significantly reduced, and after the predetermined time t has elapsed, the switching valve 22 is turned off again and the damping force increases, so the vibrations after going over the bump can be efficiently converged. I can do it. FIG. 7 shows the vertical acceleration generated in the vehicle body when the vehicle passes over a bump, and it is clear that the ride comfort is improved by performing the above switching.

According to the above embodiment, relatively low frequency vibrations can be efficiently absorbed by the operation of the extraction actuator 14, and at the same time, when high frequency vibrations are input, the first and second orifices 19 and 21 act. This provides the effect of efficiently damping input vibration. Moreover, the control valve 17
Since a relatively small flow rate can be used as a fuel pump, there is an advantage that good riding comfort can be ensured even against high frequency vibration input without increasing cost.

Note that the present invention is not limited to the above-mentioned embodiments. For example, the switching valve 22 may be controlled only by the varying frequency of the vehicle height sensor, or the preview sensor 3 may be controlled by the vehicle height sensor.
3 may be used for control only when passing through a protrusion or a step.

Further, a variable orifice that can continuously change the orifice diameter may be used as the variable orifice means, and the orifice diameter can be continuously changed depending on the frequency of input vibration, or the control valve 17 can be controlled. As a method, you can use other forms, or use vertical G under the spring.
It goes without saying that a high-frequency road surface may be determined from the frequency of fluctuation of the unsprung speed by providing a sensor, and various other modifications can be made without departing from the gist of the present invention.

(Effects of the Invention) As described above in detail with the embodiments, according to the present invention, relatively low frequency vibrations can be efficiently absorbed by actuator operation, and at the same time, high frequency vibrations can be input. When the variable orifice means is used, input vibrations can be efficiently damped by the action of the variable orifice means, and since a control valve with a relatively small flow rate can be used, the cost does not increase significantly.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram showing one embodiment of the present invention;
The figure is a control block diagram showing the control operation of the control valve 17, FIG. 3 is a flowchart showing the control operation of the switching valve 22, FIG. 4 is a principle diagram of detecting over a projection using the preview sensor 33, and FIG. 6 is a characteristic diagram of the frequency response characteristic of the control valve, FIG. 6 is a characteristic diagram of the vibration transmission force to the vehicle body with respect to the input vibration frequency, and FIG. 7 is a characteristic diagram of the vertical acceleration generated in the vehicle body when passing over a bump. 1...Oil pump, 14...Hydraulic actuator.

Claims (1)

[Claims] An actuator disposed between a sprung member and an unsprung member of a vehicle to displace the unsprung member in the vertical direction of the vehicle according to the state of supply and discharge of hydraulic oil; and an actuator that supplies and discharges hydraulic oil to the actuator. A control valve provided to perform control, an accumulator connected to the hydraulic chamber of the actuator, a variable orifice means interposed between the accumulator and the hydraulic chamber, and the state of vibration input to the vehicle body. vibration input detection means for detecting the vibration input detection means; and control means for controlling the state of the variable orifice means when the operation of the control valve is controlled according to the detection output of the vibration input detection means, and the control means is configured to control the state of the variable orifice means. When the detection signal of the vibration input detection means corresponds to a high-frequency road surface, the orifice diameter of the variable orifice means is increased compared to when the detection signal does not correspond to a high-frequency road surface. active suspension for vehicles