KR20020049826A - Electronic control semi-active suspension - Google Patents

Abstract

The present invention relates to an electronically controlled semi-active suspension device, wherein a variable valve for adjusting the damping force in the tension stroke and a variable valve for adjusting the damping force in the compression stroke are independently configured to adjust the damping force specification for each tension and compression stroke. In an electronically controlled semi-active suspension system employing a damper, a ride comfort value for controlling the damping force corresponding to the vertical acceleration of the wheels ( ) And body vertical speed ( ) And a ride value control logic 20 for detecting a roll value for adjusting the damping force corresponding to the vehicle speed and steering angle of the vehicle ( ), The anti-roll control logic 30 that calculates the riding comfort value ( ) And body vertical speed ( Sky-hook control is implemented by adjusting the damping force of the variable valve for compression and the variable valve for compression of each wheel according to the Sky-hook control is implemented through the ride comfort control logic, including a damper control circuit 40 that controls the damping force of the tension variable valve and the compression variable valve of each wheel according to In addition, through the anti-roll control logic there is an advantage that can suppress the roll phenomenon generated during steering.

Description

ELECTRONIC CONTROL SEMI-ACTIVE SUSPENSION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled semi-active suspension of a vehicle. More particularly, the present invention relates to a variable valve for adjusting damping force during a rebound stroke in which a vehicle body is lifted and a variable for adjusting damping force in a compression stroke in which a car body sinks. Independently operated valve-type damping force variable dampers using magnetic-Rheological Fluid (MR) fluids that can be independently configured to adjust the damping force specification for each tension and compression stroke, so that the sky-hook (sky-hook) The present invention relates to an electronically controlled semi-active suspension device that implements control and suppresses a roll phenomenon during steering through anti-roll control logic.

Suspension device is a device that connects the axle and the body so that the vibration or shock received from the road surface while driving is not directly transmitted to the vehicle body to prevent damage to the body and cargo and improve ride comfort. In addition, the suspension system transmits the driving force generated from the driving wheels or the braking force of each wheel during braking to the vehicle body, and also withstands the centrifugal force during the turning and maintains each wheel in the correct position with respect to the vehicle body.

On the other hand, in the electronically controlled semi-active suspension device, various sensors are mounted in the vehicle, and the motion characteristics of the damper are varied in real time according to the information from the sensor to improve ride comfort and adjustment stability.

However, in such a semi-active suspension device, the efficiency is extremely different depending on which sensor and damper is used and how the information from the sensor is used to control the damper. It is requested.

The semi-active suspension system independently controls the damping force of the four wheels to maximize the advantages of the independent suspension system. A vertical acceleration sensor is attached to the upper body of each wheel to measure the behavior of each wheel and provide independent control. Make it possible.

The main components of this semi-active suspension consist of a vertical acceleration sensor, steering angle sensor, damper and actuator, and electronic controller.

According to the prior art, a damper variable damper is employed, and such damping force variable dampers include a reverse type semi-active damper and a normal type semi-active damper. Existed.

Reverse control logic using reverse type semi-active damper has the advantage that the sky-hook control is possible only by measuring the speed of the body. Adjusts the damping force mode to hard / soft during the tension stroke where the body is lifted and soft / hard to adjust the damping force mode during the compression stroke when the body sinks. This implements sky-hook control.

Here, briefly described with respect to the "sky-hook control" to help understand the description as follows.

When the vertical velocity of the body to the ground is V _s , the vertical velocity of the axle to the ground is V _u , and the damper operating speed V _s -V _u is defined as V _d ,

If V _s &gt; 0, the damper force mode of the damper is set to hard / soft to provide a hard damping force of V _d &gt; 0 in the tension stroke and a soft damping force of V _d &lt; 0 in the compression stroke. On the other hand, if V _s <0, the damper force mode of the damper is set to soft / hard to provide a soft damping force of V _d > 0 in the tension stroke and a hard damping force of V _d <0 in the compression stroke.

This sky-hook control is summarized in the following equation.

However, the reverse control logic using the reverse type semi-active damper described above does not provide the damping force of the sporty damper (hard / hard) necessary to implement the anti-roll logic to suppress the roll phenomenon generated during steering.

On the other hand, the normal control logic using the normal semi-active damper can suppress the roll phenomenon during steering and implement the logic using the hard damping force of the perfect sporty mode, but the number of sensors must be known because the information about the body and the axle speed must be known. There is a problem that sky-hook control can be implemented only when there are more.

Therefore, the development of a new damper that can only take advantage of the reverse control logic and normal control logic, and the development of the optimum control logic that can be applied to it is an urgent requirement.

In the past, research on electric rheological (ER) fluids, which is a type of controllable fluid, has been mainly conducted in semi-active devices such as linear dampers and mounts. However, in recent years, the ER fluid has the advantages of fast response speed while maintaining low yield stress and narrow use. Magnetic-Rheological Fluid (MR) fluids that overcome the shortcomings such as temperature range, especially susceptibility to impurities, are being actively researched.

MR fluid is a non-colloidal solution in which micron-sized particles are dispersed in a non-conductive solvent such as silicone oil or mineral oil.If the magnetic field is not loaded, the dispersed particles have Newtonian fluid properties but the magnetic field is loaded. In this case, the dispersed particles are polarized to form fibers in a direction parallel to the loaded magnetic field, thereby having a shear force or a resistance to flow.

The present invention is a result of the research and development for solving the above-mentioned conventional requirements, the variable valve for controlling the damping force during the tension stroke and the variable valve for controlling the damping force during the compression stroke is independently configured to damping force for each tension and compression stroke Independent drive valve type damping force variable damper using MR fluid with adjustable specification realizes sky-hook control through ride comfort control logic and anti-roll control logic to suppress roll phenomenon during steering The purpose is to provide a semi-active suspension device.

The electronically controlled semi-active suspension device according to the present invention for realizing such an object is characterized in that the variable valve for adjusting the damping force during the tension stroke and the variable valve for regulating the damping force during the compression stroke are independently configured to have a damping force specification for each tension and compression stroke. In the electronically controlled semi-active suspension system employing a variable damper capable of adjusting the damping force, a ride comfort value for controlling the damping force corresponding to the vertical acceleration of the wheels ( ) And body vertical speed ( Ride comfort control logic 20 for detecting (); Roll value for adjusting the damping force corresponding to the vehicle speed and steering angle of the vehicle ( Anti-roll control logic (30) for calculating; The ride comfort value ( ) And body vertical speed ( Sky-hook control is implemented by adjusting the damping force of the variable valve for compression and the variable valve for compression of each wheel according to), and the roll value ( And a damper control circuit 40 for controlling the damping force of the tension variable valve and the compression variable valve of each wheel to suppress a roll phenomenon generated during steering.

1 is a block diagram of an independent drive valve damping force variable damper using a magnetic rheological fluid for employing the present invention,

2 is a block diagram of an electronically controlled semi-active suspension device according to the present invention;

3 is a block diagram of a ride comfort control logic in an electronically controlled semi-active suspension device according to the present invention;

4 is a block diagram of anti-roll control logic in the electronically controlled semi-active suspension device according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10 damper 11: variable valve bundle

12: piston rod 20: ride comfort control logic

21: high frequency pass integrator 22: body vertical velocity RMS detector

23 body vertical velocity filtering unit 30 anti-roll control logic

31: steering ratio detection unit 32: roll value calculation unit

S1 to S4: Vertical acceleration sensor S5: Vehicle speed sensor

S6: Steering Angle Sensor

There may be a plurality of embodiments of the present invention. Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. Through this embodiment, it is possible to better understand the objects, features and advantages of the present invention.

1 is a block diagram of an independent drive valve type damping force variable damper using MR fluid employed in the electronically controlled semi-active suspension according to the present invention.

The damper 10 for the present invention has a variable valve bundle 11 is attached to the side, the variable valve bundle 11 in the tension variable valve and piston rod for adjusting the damping force during the tension stroke in the piston rod 12 (12) is independently provided with a variable valve for compression to adjust the damping force during the compression stroke.

Since the independent driving valve damping force variable damper 10 is provided with two independent damping force adjusting valves, it is possible to separately control the damping force during tension / compression stroke, and because MR fluid is used, the other variable dampers cannot be quickly implemented. Responsiveness (within 10 msec) is shown. This allows the damping force specification to be adjusted in hard / soft, soft / hard, soft / soft and hard / hard mode for each tension / compression stroke.

2 is a schematic block diagram of an electronically controlled semi-active suspension according to the present invention employing the independent drive valve type damping force variable damper shown in FIG.

The present invention, as shown, ride control logic (Ride Control Logic) 20, anti-roll control logic (Anti-Roll Control Logic) 30, damper control circuit 40, various sensors (S1 ~ S6) It is composed.

The ride comfort control logic 20 adjusts the damping force mode to hard / soft through the tension variable valve of the damper 10 during the tension stroke in which the vehicle body is lifted, and adjusts the damping force mode through the variable valve for compression in the compression stroke in which the vehicle body sinks. By adjusting the soft / hard to implement the sky-hook control, the vehicle movement is controlled to improve the riding comfort.

As shown in FIG. 3, the ride comfort control logic 20 includes a high-frequency pass integrator 21, a vehicle vertical velocity root mean square (RMS) detector 22, and a vehicle vertical velocity filter 23.

Four vertical acceleration sensors S1 to S4 are connected to the high frequency pass integrator 21, and the vertical acceleration sensors S1 to S4 detect vertical accelerations of the four wheels, respectively, to the high frequency pass integrator 21. Is authorized. Meanwhile, although four vertical acceleration sensors S1 to S4 are used in the embodiment of FIG. 2, it will be readily understood by those skilled in the art that only three vertical acceleration sensors can detect the vertical acceleration of four wheels.

Equation 2 below shows the z-domain and s-region of the high-frequency pass integrator 21.

The high-frequency pass integrator 21 removes a low frequency signal including a direct current value among the vertical acceleration signals applied from the vertical acceleration sensors S1 to S4, and a frequency domain according to a designer's intention as shown in Equations 3 and 4 By integrating at the vertical velocity ( Calculate

Where ζ ₁ and ω ₁ are design variables. In addition, the superscripts of the alphabet representing the physical quantities in Equations 3, 4 and the following Equations indicate frequency bands to be filtered, and all individual logics are independent of four wheels, respectively.

Next, the vertical speed ( In order to determine the average size of), the absolute value of the vertical velocity is taken as shown in Equations 5 and 6 and filtered through a 0.5 [㎐] low pass filter.

Here, T is a variable value for a predetermined time delay.

The vehicle body vertical velocity RMS detector 22 detects a ride value by performing the following equation (7) using the output values of equations (5) and (6).

here, Is the filtered vertical speed, ( , ), ( , ) Value means a predetermined gain value.

In addition, the vertical acceleration signal is filtered by the vehicle body vertical velocity filtering unit 23 by a 10 [㎐] band pass filter having the characteristics of Equations 8 and 11, and then squared by Equations 9 and 12, The average value is obtained by filtering with a 3 [㎐] first-order low pass filter having the same characteristics as 13.

The vehicle body vertical velocity filtering unit 23 detects the detected average value and the equations (3) and (4). With the body vertical speed ( ) Is detected as in Equation 14.

here, ( , ) Is the tuning variable.

Bodywork vertical speed ( ) Is applied to a damper control circuit 40, which will be described later, The acceleration signal that is input is larger as the curse is reduced and becomes smaller as the frequency is higher. In other words, if the vehicle acceleration input is high frequency, the output becomes small. This feature is to ensure a comfortable ride by maintaining a soft damping force when there is a high frequency input to the vehicle body.

The anti-roll control logic 30 is to suppress the roll motion of the vehicle by increasing the damping force of the damper during steering of the vehicle, and is connected to the vehicle speed sensor S5 and the steering angle sensor S6 as shown in FIG. 4. have. That is, the anti-roll control logic 30 detects the steering input of the driver and controls the transient area of the body behavior. The anti-roll control logic 30 detects the steering angular velocity by inputting a signal from the steering angle sensor S6, and applies the steering angular velocity to the steering angular velocity. The change amount of the lateral acceleration and the roll value are detected in consideration of the vehicle speed from the vehicle speed sensor S5.

On the other hand, the damping force of the damper is a function of the vertical speed up and down, so the roll value should contain information about the roll speed. Here, the roll speed representing the roll angle is the lateral acceleration ( Is proportional to the lateral acceleration ( ) Can be obtained from steering angle displacement and vehicle speed. The derivative of the roll speed is the lateral acceleration ( It is calculated by the amount of change of), and the roll value is calculated by detecting the steering angle speed.

The steering ratio detector 31 uses the equation 15 to determine the lateral acceleration, which is the movement of the wheel with respect to the steering input angle. ) The steering ratio ( Detection).

here, Is the steering gear ratio, Is the steering wheel angle rate (degree / sec), Silver wheel base, Is the vehicle speed (m / sec), and Is the characteristic speed.

On the other hand, in a real system, the lateral acceleration for steering input ( ) Has a first order delay, so the lateral acceleration ( ), The low frequency filtering results in a lateral acceleration ) Should be obtained.

Lateral acceleration in the steering ratio detector 31 ( ) Value is applied to the roll value calculator 32, and the roll value calculator 32 performs the equation (18) to determine the roll value ( )

here, ( , ) Is a variable representing a predetermined gain value, and can be obtained through Equation 19. λ is the slip ratio, and Is the rear and front wheel radius, Wow Is the rear and front wheel speed.

The damper control circuit 40 combines the signals from each of the above-described logics 20 and 30 to perform equation (20) to apply damping force to each wheel ( ) To drive the variable and tension variable valves in the variable valve bundle 11 attached to the side of the damper 10.

here, Silver tension valve damping force, Is the compression valve damping force.

Through Equation 20 and When the tensile current is finally obtained through the following equations 21 and 22, ) And compression current ( ) Is calculated.

The damper control circuit 40 has a ride comfort value inputted through the ride comfort control logic 20. ) And body vertical speed ( Calculated according to) ) And compression current ( Sky-hook control is implemented by individually controlling the tension variable valve and the compression variable valve of the damper 10 according to the present invention, and the roll value input through the anti-roll control logic 30 ( Calculated according to) ) And compression current ( By controlling the tension variable valve and the compression variable valve of the damper 10 separately, the roll phenomenon generated during steering using the hard damping force of the sporty mode is suppressed.

In addition, the independent drive valve type damping force variable damper 10 and the anti-roll control logic 30 using MR fluid according to the present invention are the four-wheel speed sensor, yaw rate of the brake system ABS, VDC, TCS that are currently common. The yaw rate sensor and pressure sensor provide the suspension performance required for vehicle braking and behavior as well as the anti-roll side. In order to cope with the wheel information, the damping force should be varied as fast as possible. This is because the damper of the present invention not only has variable damping force characteristics but also has a fast response within 10 msec that cannot be implemented by other variable dampers because it uses MR fluid. .

As described above, the present invention is a magnetic valve capable of adjusting the damping force specification for each of the tension and compression stroke is independently composed of a variable valve for adjusting the damping force during the tension stroke to lift the vehicle body and a variable valve for adjusting the damping force during the compression stroke to sink the vehicle body. Independent driving valve type damping force variable damper using rheological fluid is adopted to implement the sky-hook control through the ride comfort control logic and also to suppress the roll phenomenon caused by steering through the anti-roll control logic.

Claims (13)

In the electronically controlled semi-active suspension system employing a variable valve for adjusting the damping force during the tension stroke and a variable valve for adjusting the damping force during the compression stroke, and adopting a damping force variable damper that can adjust the damping force specifications for each tension and compression stroke, Riding comfort value for controlling damping force corresponding to the vertical acceleration of the wheels ) And body vertical speed ( Ride comfort control logic 20 for detecting (); Roll value for adjusting the damping force corresponding to the vehicle speed and steering angle of the vehicle ( Anti-roll control logic (30) for calculating; The ride comfort value ( ) And body vertical speed ( Sky-hook control is implemented by adjusting the damping force of the variable valve for compression and the variable valve for compression of each wheel according to), and the roll value ( And a damper control circuit (40) for suppressing a roll phenomenon generated during steering by adjusting the damping forces of the tension variable valve and the compression variable valve of each wheel. 2. The ride comfort control logic 20 of claim 1 The vertical acceleration sensors S1 to S4 respectively configured to the wheels are connected, and the vertical speed (B) is integrated by integrating the signals of the vertical acceleration sensors S1 to S4. A high frequency pass integrator 21 for detecting (); The ride comfort value (from the vertical speed of the high frequency pass integrator 21 A vehicle body vertical velocity RMS detector 22 for detecting); From the vertical speed of the high-frequency pass integrator 21 the vertical body speed ( Electronically controlled semi-active suspension device comprising a vehicle body vertical speed filtering unit (23) for detecting. 3. The high frequency pass integrator 21 according to claim 2, wherein When the z-domain and s-domain are By removing a low frequency signal including a direct current value among the vertical acceleration signals applied from the vertical acceleration sensors S1 to S4 and integrating in the frequency domain according to the designer's intention as shown in the following equation. (Where ζ ₁ and ω ₁ are design variables, the frequency band in which the superscript of the alphabet representing the physical quantities is filtered) Vertical speed ( Electronically controlled semi-active suspension, characterized in that 4. The high frequency pass integrator 21 according to claim 3, wherein The vertical speed ( To determine the average size of) (Where T is a variable value for a predetermined time delay) The vertical speed ( Electronically controlled semi-active suspension, characterized in that the absolute value of) and filtered through a low pass filter having the above characteristics. 3. The vehicle body vertical velocity RMS detector 22 according to claim 2, By doing the following formula (here, The filtered vertical speed, , Value is a predetermined gain value) An electronically controlled semi-active suspension device for detecting a ride value. The vehicle body vertical velocity filtering unit 23 of claim 2, The vertical acceleration signals applied from the vertical acceleration sensors S1 to S4 are characterized by the following equations. Filter with a band pass filter, As shown below Squared, Having the same characteristics as the following formula An electronically controlled semi-active suspension comprising filtering with a low pass filter to detect an average value. 7. The vehicle body vertical speed filtering unit 23 is according to claim 6, The detected average value and the previously detected vertical velocity ( According to the following formula using (here, Is a tuning variable) Bodywork vertical speed ( Electronically controlled semi-active suspension device characterized in that it detects. 2. The anti-roll control logic 30 of claim 1 wherein Lateral acceleration, which is the movement of the wheel with respect to the steering angle ( ) The steering ratio ( ) And detect the lateral acceleration ( ) Is low-frequency filtered and its value (the lateral acceleration A steering ratio detecting unit 31 for detecting)); Lateral acceleration value of the steering ratio detector 31 ) To a given gain value ( Multiplying the roll value ( Electronically controlled semi-active suspension device comprising a roll value calculation unit (32) for detecting). The method of claim 8, wherein the steering ratio detector 31 The following formula (here, Silver steering gear ratio, Is the steering wheel angle ratio (degree / sec), Silver wheel base, Is the vehicle speed (m / sec), Feature speed) Lateral acceleration, which is the movement of the wheel relative to the steering input angle, ) The steering ratio ( Electronically controlled semi-active suspension device characterized in that the detection. The method of claim 9, wherein the steering ratio detector 31 Lateral acceleration for steering input ( Since the output of) has a first order delay, Lateral acceleration ( ), The low frequency filtering results in a lateral acceleration Electronically controlled semi-active suspension device, characterized in that The method of claim 8, wherein the roll value calculator 32 The lateral acceleration value in the steering ratio detector 31 Value) (here, ( , ) Is a certain gain value) Roll value ( Electronically controlled semi-active suspension device, characterized in that The method of claim 11, wherein the roll value calculator 32 Through the following formula (Where λ is the slip ratio, and Is the rear and front wheel radius, Wow Rear and front wheel speed) The gain value ( , Electronically controlled semi-active suspension device, characterized in that The damper control circuit 40 of claim 1, wherein the damper control circuit Tension valve damping force through ) And compression valve damping force ( ) Is found Through the following formula Tensile current ( ) And compression current ( Electronically controlled semi-active suspension device characterized in that it calculates.