Variable damping controller for vehicle suspension system

The present invention relates to a control device for adjusting the arranged damping force between the vehicle body and the wheels Vibration dampers of a vehicle suspension to the vibrations of the to suppress vehicle body.

In EP 0246772 A1 is known a vehicle suspension described that, a spring is provided between the vehicle body and each wheel of a Vibration at each spring, an accelerometer for Vertical movement of the vehicle body and control means for switching the Anti-vibration damper between hard and soft Has settings whenever the vertical motion of a predetermined value within a low frequency range of the vehicle body vibration exceeds.

In DE 36 32 919 A1 describes a known method of Damping force adjustment of motor vehicles is described in which an output signal an acceleration sensor through a first and a second measuring time slidingly is averaged, the difference of both mean values ​​is formed, and with a Threshold value is compared. When exceeding or falling below the threshold, the Damping force or spring force changed. The measurement times are larger or smaller than the proper time (reciprocal proper frequency) of the vehicle body.

The DE 39 41 909 A1 (only relevant under the Patents Act §3. 2) describes a known suspension control in which the differential of transverse acceleration of the Vehicle body is monitored between a compression, a waver and a steady running condition to differ and the suspension characteristics then adjust.

For improving the ride comfort during running of the vehicle, it is generally better, the characteristics of the suspension of a vehicle body (Vehicle body) adapted to ensure that it is SOFT. Specifically, it is better, that a damping force (or loss) is reduced the suspension that a Spring constant of the suspension is small and soft and that the torsional stiffness a stabilizer is reduced. On the other hand, it is for improving the steering stability convenient to adjust the behavior of the suspension of the vehicle body on HART or it adapt. More specifically, it is better that the damping force of the Suspension is large, the spring constant of the suspension is large and hard and that the torsional rigidity of the stabilizer is large.

A switching system has been developed, the characteristic of the Suspension in normal driving condition on SOFT (or MEDIUM between HART and SOFT) set and the characteristic means of a HART Fahrumstelleinrichtung for switching the characteristics of the suspension switches according to the requirements and the need to HART when z. B. a change in the road surface condition or the position of the Vehicle body occurs. Such a system is z. B. in Japanese Laid-Open Patent Application JP 60-47709 A describes the duration of the acceleration above a predetermined value of the oscillations of the vehicle body is measured, wherein only when the duration is not less than a predetermined time period, the damping force of the suspension is raised or the spring constant of Suspension is increased.

In this system, a low driving comfort is given as Vertical vibrations of the vehicle body in the vicinity of the Resonance frequency of the sprung mass on the basis of the duration of the are acceleration, if this is greater than a predetermined value, is detected whereby the characteristics of the suspension can be controlled only approximate. In this case it is not possible before not at least a half cycle period time the decision frequency in the vicinity of the resonance frequency of the suspension has passed, to decide whether the characteristics of the suspension suitable is or not controlled, whereby the control is delayed. Another disadvantage is that an initial, large shock caused when the Vehicle travels over a large hill or a collection, or a large difficult controlled change in position of the vehicle body in a suitable manner can be respectively controlled.

It is also judged or decided whether the vehicle on a bad road driving and the characteristic of the suspension or stabilizer is on medium on the basis of the frequency of the vibration of the unsprung Mass or on the basis of a vertical or lateral vibration pattern of converted the vehicle body, whereby control is performed to a good maintain ride comfort, and in order to remain in contact with the road. In this Case, the control can not be performed, not even on a bad Street until a reliable decision regarding the frequency of oscillation or the vibration pattern has been made.

According to the above embodiments, it is with respect to an initial Vibration state or an initial phase of vibration of the Vehicle body not clear if the characteristics of the suspension or the Stabilizer HART or MEDIUM is to be, and much time is needed to a optimum control parameter only from the information of the oscillation frequency to determine. Also, in the subsequent phase, when the waveform A Pattern of a complicated overlay of oscillation of the sprung with the Vibration of the unsprung mass reproduces the following decision imperfect and there is the possibility that the decision is further delayed is, as A in the Japanese Laid-Open Patent Application JP 63-8010 is described.

The object of the present invention is to provide a indicate control device that reliably one to the vehicle body applied shock and unnecessary vibrations suppressed, even if the vehicle traversing a relatively high elevation. In addition to a control device be specified that a bad driving comfort in the shortest possible time, by a wrong decision could be caused, prevented.

This object is achieved by the control device according to claim 1 dissolved.

Advantageous developments of the present invention are disclosed in the dependent claims.

Advantages and possible applications of the present the invention are apparent from the following description of Embodiments in conjunction with the accompanying Drawings. Show it:

<b>Fig.</b> 1 is a block diagram showing the basic construction of egg ner control device according to the present invention shows;

<b>Fig.</b> 2 is a perspective view showing the state of the shows, in which the individual devices in a driving convincing are attached, when the present invention is turn is to the damping force of a suspension switch switch;

<b>Fig.</b> 3 is a block diagram showing the structure together and the game of the facilities after <b>Fig.</b> 2;

<b>Fig.</b> 4 is a flowchart showing the flow from a implementation of the present invention.

<b>Fig.</b> 1 is a block diagram of a control apparatus according to of the present invention, in which a vehicle body <b>1</b> (Vehicle body) with an acceleration detection device <b>2</b> for Detek animals of the vertical acceleration, the Lateralbeschleuni tion or the accelerations in both directions of the vehicle body <b>1</b> is used to a detection signal, the acceleration of the detection device <b>2</b> generated is, to a control device <b>7</b> output. between each the bike <b>3</b>a or <b>3</b>b and the vehicle body <b>1</b> is on imposition arranged as a supporting unit. Between the wheels<b>3</b>a and <b>3</b>b is arranged a stabilizer. A damping force of the suspension can be between three Stel ments or gradations according HARD,, SOFT means changing means <b>4</b> for the damping force (damping) as order switch means are switched or changed. A Spring constant of the suspension will ge in three gradations according HARD, SOFT, and via a Änderungsein direction <b>5</b> for the spring constant as a switching device switched. Further, the Torsional rigidity of the stabilizer according to three Abstufun gen HARD, SOFT, and via a Änderungseinrich tion <b>6</b> for torsional rigidity than switching converted. The change means<b>4</b> for the damping force, the change means <b>5</b> for the spring constant and the changing means <b>6</b> for torsional rigidity Change all the Charakterisstik the suspension accordingly a command signal from the control means <b>7</b>, The controller <b>7</b> determines or decides the size the acceleration and the vibration cycle length (period of oscillation) of the acceleration on the basis of the signal from the Acceleration detection device <b>2</b>Wherein it to each Change means the command signal for changing the Cha rakteristik outputs.

The <b>Fig.</b> 2 and 3 show an example of the application the control device according to the present invention, and Although for switching or changing the damping force of the Suspension, wherein the control means <b>7</b>That a microcomputer which outputs or outputs of a steering sensor <b>11</b> for detecting the steering state of Hal test is (handle), a speed sensor <b>12</b> to De tektieren the vehicle speed, an acceleration acceleration sensor <b>13</b> for detecting the operation with respect to egg ner acceleration and a deceleration of the Fahrzeugkör pers <b>1</b>, A brake switch <b>14</b> for detecting the braking operative, an acceleration sensor <b>20</b> as acceleration movement detection means for detecting the Vertikalbe acceleration of the vehicle body <b>1</b> and a selection Scarf ters <b>15</b> to set a standard for decision the characteristic of the damping force can be supplied. The controller <b>7</b> controls four changing means <b>4</b> for the damping force for changing the characteristics of the four suspensions (suspension system) and a display <b>16</b>That the outputs is assigned from these sensors and switches.

The acceleration sensor <b>20</b> for detecting the vertical acceleration uses an accelerometer, z. B. made of a piezoelectric member, a sensor from the Differential transformer type or an acceleration sensor Type a Halbleiterdehnungsmeßstreifens for a people vehicle may be made, and are continuously Verti kalbeschleunigung in the form of an analog voltage in depen pendence from baseline during the zero acceleration out. The output of the acceleration sensor<b>20</b> is ana log / digital converted, and then the controller <b>7</b> supplied, and the signal value and the change in time of this Output signal are determined. According to the Ausfüh embodiment according <b>Fig.</b> 2 is an acceleration sensor <b>20</b> the center of gravity of the vehicle body <b>1</b> attached whose Be mounting position but also at the extreme end of the driving generating body <b>1</b> may be, or the number of sensors <b>20</b> can be two, namely a front, and the other rear, or in each case, a sensor can be connected to each suspension be provided for each wheel.

According to <b>Fig.</b> 4 be a differentiated value of the acceleration and the Vibration cycle period of acceleration based on the information and the signal from the Be schleunigungsdetektionseinrichtung <b>2</b> determined so that a command signal may be output, the result of the the decision or review this shall be at the changing means <b>4</b> for the damping force to the changing means <b>5</b> for the spring constant and to the changing means <b>6</b> for torsional rigidity.

Next, an explanation will be made of the sequence and the processing within the controller <b>7</b> ge according to the embodiment with reference to the <b>Fig.</b> 4 given.

First, at step S1, a signal of the acceleration acceleration sensor <b>20</b> read, then at step S2 a differen ed value of the vertical acceleration at the border of a predetermined reference point (± floor), or in other words a change in acceleration per unit time ermit, mined, and then in step S3 Vibrationszy klusperiode the acceleration not less than a pre- declared value by means of a full cycle period or a half cycle period determined.

At step S4, it is judged if the differentiated value the acceleration is not smaller than a second pre give ner value is generated or not. If it is generated (YES at step S4), the processing proceeds to step S5 continued. At step S5, the damping force of the hang point is supply set to HART and the timer for maintaining This state will ge to a predetermined value set to start counting. If at step S4 NO, processing proceeds to step S6 continued.

At step S6, it is judged whether the timer for Beibe hold the higher damping force is in operation or not. When it is in operation (YES at step S6) screaming tet processing proceeds to step S7. When he is not in Operation (NO in step S6), below the proces processing to step S11, thereby the damping force reset to the basic value SOFT.

In step S7, it is judged whether the measurement of the vibrato onszyklusperiode the acceleration is finished and the conditions for maintaining the current state (HART) are met or not. If they are satisfied (YES expressed in step S7), or otherwise, if the Oscillation frequency by means of a full cycle period or a half cycle period of the oscillation of the acceleration not less than the first predetermined value is calculated wor the is, in the vicinity of the resonant frequency of the vehicle body <b>1</b> is, at step S8 of maintaining current state of HART and a timer for maintaining HART is a predetermined time value is reset to continue the counting. If you are not satisfied (NO at step S7), the proceeds Processing proceeds to Step S9 to judge whether the Measuring the vibration cycle period of acceleration from is closed and the conditions for changing HART on MEDIUM are met or not.

If the conditions are met for changing HART on MEDIUM are expressed (YES in step S9), or otherwise, when the Magnitude of the acceleration is about "medium" or mediocre, although the oscillation frequency in is close to the resonance frequency of the sprung mass or the vibration frequency in the vicinity of the resonant frequency the unsprung mass is, is converted the damping force at MEDIUM at step S10 and a timer for maintaining MEDIUM is set (Or reset). On the other hand, if NO at Step S9 is given, the present condition is not changed and the processing returns.

When it is intended that it is judged at step S4, whether the differentiated value of the acceleration is not less than the second predetermined value or not and whether the Acceleration is not smaller than a predetermined value or not, this is effective when an end to decay continuous shock or an expiring vibration.

In the embodiment mentioned above is an example for controlling the damping force of a hang tion described, the spring constant of the suspension and Torsional rigidity of the stabilizer can but similarly Way be controlled. Of course, then, all these Variables are simultaneously controlled.

As is standing mentioned above, the damping is with respect to three grades according to SOFT, MEDIUM and HARD converted. but the invention is not limited to three Abstufun gen limited. The present invention is also in a Case applicable where the attenuation with respect to two From downgrades or foursome gradations or more Abstufun is gen convertible.