DE102008050142A1 - Method and apparatus for calculating a damper target force for an adjustable damper element - Google Patents

Abstract

The invention relates to a method and a device for calculating a Dämpfersollkraft (Fsoll, n) for an adjustable damper element (...) of a spring-damper system, which supports the vehicle body of a vehicle relative to the vehicle wheels of the vehicle resiliently and damping the damper element associated spring element has a variable spring stiffness (Cn) and the Dämpfersollkraft (Fsoll, n) is determined depending on the variable spring stiffness (Cn). Further, a lateral acceleration amount (ayK) describing the lateral acceleration is obtained, and the damper target force (Fsoll, n) is determined depending on the lateral acceleration amount (ay, calc).

Description

The The invention relates to a method for calculating a damper target force for an adjustable damper element after the The preamble of claim 1 and an apparatus for calculating a Damper set force for an adjustable damper element according to the preamble of claim 21.

Such a method and such a device is known from DE 199 40 198 C1 known.

The Document discloses a spring-damper system that the System damping adapts to spring stiffness. In a Control unit are in a first process step depending on the driving situation Spring stiffness of the air spring and subsequently the total damping of the system. This is done first a frequency analysis of the currently oscillating motor vehicle part, which associated with the respective air spring with additional volume is. Subsequently, the determination of the attenuation quantity depending on the throttle resistance of a throttle, which is arranged between the air spring and an additional air volume is, and the current vibration frequency motor vehicle part. therefore is the still required residual attenuation of the total attenuation determined by the control unit, wherein the shock absorber throttle adjusted so that the sum of the air spring damping and residual attenuation corresponds to the default value.

Of the Invention is the object of a device and an improved Method for calculating a damper target force for to specify an adjustable damper element.

These Task is by the combination of features of claim 1 and / or solved by the combination of features of claim 21.

According to the invention a lateral acceleration magnitude describing the lateral acceleration determined, the damper target force additionally dependent is determined by the lateral acceleration quantity.

Thereby can be a spring-damper system with a high ride comfort and high driving safety.

advantageous Embodiments of the invention will become apparent from the dependent Claims.

Preferably Each vehicle is assigned a damper element and for each damper element is separately a damper desired force determined. This allows each single wheel on the respectively assigned Damping element individually and in dependence optimally attenuates the roadway excitation prevailing on the individual wheel become possible, whereby possible different suggestions the single wheels is taken into account. Thus, a Increasing driving comfort and driving safety.

Thereby, the damper target force is proportional to the lateral acceleration magnitude depends, the spring damper system at high Transverse forces stronger damped, causing the contact between road surface and vehicle wheel improved and thus the driving safety, especially when cornering increased becomes.

It is also advantageous that the lateral acceleration quantity based on a vehicle longitudinal velocity and a steering angle calculated lateral acceleration is determined. The of the steering angle and the vehicle longitudinal speed dependent leadership hurries the actual lateral acceleration of the vehicle in time ahead. As a result, the damper target force and z. Belly the axle rigidity is adapted to the upcoming situation, already before the actual effect of the lateral acceleration on the vehicle. This time advantage serves the vehicle already at the time of steering at the beginning of driving through a Curve to adjust the self-adjusting lateral acceleration and the vehicle dynamics behavior of the vehicle for cornering optimally adapt.

especially the lateral acceleration at the respective damper elements forms differently, is expediently for the calculation of the damper target force on a Damper element each on this damper element prevailing calculated lateral acceleration. Thereby can be for each damper element one achieve optimum damping effect, thereby increasing ride comfort and increase driving safety.

Thereby, that the calculated lateral acceleration by means of a first factor scales and from this the lateral acceleration quantity is determined, wherein the lateral acceleration dependent first factor in particular additionally dependent from the vehicle longitudinal speed or vehicle longitudinal speed ranges is predetermined, the lateral acceleration quantity adjusted by the first factor to a desired value range become.

Preferably, the lateral acceleration-dependent first factor approaches asymptotically with increasing calculated lateral acceleration Maximum value of the first factor, which is the same in particular for all vehicle longitudinal speeds or vehicle longitudinal speed ranges. As a result, a limitation of the lateral acceleration variable is possible, which increases driving safety.

Thereby, that the vehicle longitudinal speed over a second factor scales and from this a scaled longitudinal vehicle speed can be determined in a simple way an adjustment the vehicle longitudinal speed to a desired Range of values as a basis for calculating the damper target force respectively. Furthermore, the scaled vehicle longitudinal speed be used for calculating the damper target force, wherein the damper target force in particular proportional to the scaled vehicle longitudinal speed depends. Similarly, the second factor may be a value between a minimum value of the second factor and a maximum value of the second factor, causing a limitation of the scaled vehicle longitudinal speed and thus allows an improvement in driving safety is. Further, the second factor may be below a lower speed threshold correspond to the minimum value of the second factor or decreasing Vehicle longitudinal speed the minimum value of the second In particular, approximate factor asymptotically. Furthermore, can the second factor above an upper speed threshold correspond to the maximum value of the second factor or with increasing Vehicle longitudinal speed the maximum value of the second In particular, approximate factor asymptotically. The named Possibilities can each for themselves or in combination to improve the damping target force adjustment contribute to the driving situation.

Preferably a damper speed is determined and at the Determination of damper target force taken into account, whereby the ride comfort is improved. For example, the Damper target force proportional to the damper speed depends.

One Another advantage is seen in the fact that the damper speed over a third factor is scaled and therefrom a scaled damper speed is determined. This is the adjustment of the damper speed to a desired range of values as a basis for calculating the Dampersollkraft easily possible.

Of Furthermore, the third factor has a rebound value for a damper speed greater than Zero and a pressure step value different from the rebound value for a damper speed less than zero on, wherein the Zugstufenwert and / or the pressure step value in particular constant are. This is another comfort improvement and in particular an improved contact between vehicle wheel and road surface allows. For example, the damper desired force depending on the scaled damper speed be determined, the damper target force in particular proportional to the scaled damper speed depends.

Farther is it possible that on the basis of changeable predetermined spring stiffness a wheel-related damping size is calculated. Based on this wheel-related attenuation quantity Can be very easy with the help of a spring-damper system-dependent translation calculated a built-up attenuation quantity are then used to determine the damper target force can.

Preferably it is in the spring element with a gas spring element variable spring stiffness, wherein in particular several over a valve assembly fluidly interconnected and fluidic separable gas spaces are provided. Thereby is a variable spring stiffness or axle rigidity achieved by connecting or disconnecting the different gas spaces.

in the Below is an embodiment of the invention based the accompanying drawings explained.

there demonstrate:

1 a schematic representation of a vehicle with a gas spring system according to the invention in a schematic, block diagram-like representation,

2 a schematic, block diagram similar representation of a multi-chamber gas spring with adjustable dampers,

3 a block diagram of the control of the multi-chamber gas spring and the damper after 2 .

4 a block diagram of a way of determining the damper desired force of the damper after 2 .

5 the qualitative course of a lateral acceleration-dependent first factor,

6 the qualitative course of a longitudinal speed dependent second factor and

7 the qualitative course of a damper speed-dependent third factor.

1 shows a schematic and block diagram representation of a motor vehicle 1 with a view from above.

The car 1 has in a vehicle longitudinal direction x at least two, with an axial distance D, mutually parallel spaced and not shown axes, wherein at the axial ends of the axis respective at least one vehicle 2 is arranged and wherein at least one axle steerable vehicle wheels 2 wearing. According to example, each vehicle wheel 2 a spring-damper system, with a spring element 3 and an adjustable damper element 4 assigned, The spring element 3 , especially as a multi-chamber gas spring 3 formed with a variable spring stiffness c _n , the relative movements of the respective associated vehicle wheel springs 2 opposite the vehicle body. Furthermore, the damper element dampens 4 the relative movements between the respectively associated vehicle wheel 2 and the vehicle body. Accordingly, the contact between the vehicle wheel 2 and optimizes the road surface and thus optimizes ride comfort and driving safety.

This occurs in a moving motor vehicle 1 a steering angle, the vehicle rotates about the vehicle vertical axis z in the direction of the steering angle. Consequently, a transverse acceleration a _{y, calc, n forms} , which is in a vehicle transverse _direction y of the motor vehicle 1 acts. Since the lateral acceleration a _{y, calc, n} on the vehicle and in particular on the respective vehicle _wheels 2 forms an exemplary conversion of the third wheel for the third wheel (n = 3) associated lateral acceleration a _{y, calc, 3} a yaw rate ψ .., which indicates the angular velocity of rotation about the vehicle's _{vertical axis} z.

The following applies: a y, calc, 3 = a y, calc, 1 - D ..

2 shows schematically and block diagram similar to the spring element 3 in the form of a multi-chamber gas spring 3 that have a control device 5 is controllable, wherein the control device 5 For example, an integrated processing unit 5 or, in a further embodiment according to the invention, by switching technology with an external computing unit 5 connected is.

The spring element 3 has one with a rolling bellows 6 interacting gas filled gas space 7 in the form of a main chamber 7 with a main chamber volume V1. In a relative movement of the associated vehicle wheel 2 and the vehicle body is the rolling bellows 6 shifted, causing the gas in the multi-chamber gas spring 3 depending on the direction of movement of the rolling bellows 6 compressed or decompressed, so that the relative movement between the associated vehicle wheel 2 and the vehicle body, not shown, is sprung.

The spring stiffness c _{n of} the respective multi-chamber gas spring 3 depends on the effective total volume available for compressing / decompressing during the rolling-bellows movement. Consequently, you can contact the main chamber 7 at least one additional chamber fluidly connected as additional volume or again from the main chamber 7 be separated. In the embodiment described here, the multi-chamber gas spring 3 a first secondary chamber 8th , a second side chamber 9 and a third side chamber 10 on. The first secondary chamber 8th has a first secondary chamber volume V2, the second secondary chamber 9 a second secondary chamber volume V3 and the third secondary chamber 10 a third secondary chamber volume V4, in the present case V2 <V3 <V4 <V1.

The variable spring stiffness c _{n of} the multi-chamber gas spring 3 depends on how big that is with the rolling bellows 6 co-acting gas volume, which should be referred to as the effective total volume. This effective total volume results from the sum of the main chamber volume V1 and the secondary chamber volumes V2, V3, V4 of those secondary chambers 8th . 9 . 10 , which at the time considered fluidly with the main chamber 7 are connected.

The first secondary chamber 8th is via a first connection channel 11 with the main chamber 7 connected, wherein in the first connection channel 11 an electrically controllable, first connecting valve 12 is arranged. Corresponding to this is the main chamber 7 with the second secondary chamber 9 via a second connection channel 13 connected in which a second connecting valve 14 sits, and the main chamber 7 is with the third side chamber 10 via a third connection channel 15 connected, in which a third connecting valve 16 is arranged. All three connection valves 12 . 14 . 16 can by the control device 5 be controlled independently of each other and the respective connection channel 11 . 13 . 15 either fluidly close or fluidly open, so that the respective secondary chamber 8th . 9 . 10 with the main chamber 7 is fluidically separable or connectable. By way of example, the connecting valves 12 . 14 . 16 designed as switching valves. Alternatively, it would also be conceivable, the connecting valves 12 . 14 . 16 as proportional valves, so that the flow cross section of the respective connecting channel 11 . 13 . 15 continuously changed between a fully closed and a fully open position becomes.

The control of the connection valves 12 . 14 . 16 takes place electrically by energizing the respective electromagnet of the connecting valve 12 . 14 . 16 , Furthermore, the connecting valves 12 . 14 . 16 be designed as normally closed valves, so that in case of a fault in the gas spring system, which leads to a power failure, the connecting valves 12 . 14 . 16 close automatically. As a result, the axis stiffness is increased to a maximum in the event of a fault.

For setting a damper target force F _{soll, n} is the control device 5 with the adjustable damper element 4 connected by switching technology, wherein the particular hydraulically acting damper element 4 separately formed or in the respective spring element 3 can be integrated. Each damper element 4 the vehicle has for this purpose a controllable damper valve 4a on.

In the embodiment according to the invention, the control device or arithmetic unit 5 , via a not-shown sensor device of the motor vehicle 1 , a steering angle α and a vehicle longitudinal speed ν _x conveyed. Furthermore, the control device 5 be supplied via the sensor device further parameters P _w , such as vehicle condition parameters or environmental parameters. The from the sensor device to the control device 5 passed sensor data and parameters are available today in the vehicles and can via a vehicle data bus system to the controller 5 be transmitted. It is understood that further parameters can be passed on to the control device, such as the road friction coefficient.

Based on 3 and 4 In the following, the function of the control device or arithmetic unit 5 of the spring-damper system explained in detail.

3 shows the controller 5 , Parameter P _w , such as steering angle α, vehicle longitudinal velocity ν _x , lateral acceleration a _{y, calc, n} , a damper velocity ν _{D, n} and other parameters P _w are detected by at least one suitable detection unit, in particular by one or more sensors and to the controller 5 forwarded. The control unit 5 has a first control part 5.1 on, based on the transmitted parameters P _w or at least a part thereof, the spring stiffness c _n for each of the spring elements 3 determined. These spring stiffnesses c _n are sent to a second control part 5.2 forwarded therefrom and further from further parameters P _w the damper target forces F _{soll, n} for each damper element 4 of the vehicle.

The index n is used to distinguish the size of the existing separate spring elements 3 or damper elements 4 assigned. In a vehicle with four wheels and thus four spring and damper elements 3 . 4 n = 1, 2, 3 or 4.

In the 3 A connection shown with a dashed line is intended to mean a non-exclusive use of the same parameters P _w by a control device or arithmetic unit 5 represent. In other words, it is conceivable that a parameter P _w by the control device 5 and / or by the computing unit 5 or processed by other signal processing systems.

Based on the parameter P _w determines or calculates the controller or computing unit 5 for each damper element 4 an individual damper target force F _{soll, n} and, on the basis of the calculated damper target force F _{soll, n,} generates an electric valve control current I _valve for actuating the valves 4a the damper elements 4 ,

gegeben, wobei eine Fahrzeugmasse m als feste Größe vorgegeben und D eine Konstante ist.In 4 is the determination of the damper target force F _{soll, n} for each damper element 4 shown in block diagram form. In this particularly preferred embodiment of a method for calculating the damper target force F _{soll, n} for an adjustable damper element 4 will be in a first block 30 determined on the basis of variably predetermined spring stiffness c _n a wheel-related damping amount d _wheel . A particularly simple way of calculating this variable is via the following relationship d _Rad =

given a vehicle mass m given as a fixed size and D is a constant.

Since the wheel-related damping variable d _Rad does not take into account a mechanical translation i of the axle, in a second block 31 by means of the ratio i a built-up attenuation quantity d _m , which is dependent on the respective underlying spring-damper system, calculated: d _m = i ² · d _rad

In another parallel or subsequent third block 32 , a calculated lateral acceleration a _{y, calc, n is formed} from the steering angle α and the vehicle longitudinal velocity ν _x . This is followed by a fourth block 33 the calculated lateral acceleration a _{y, calc, n} scales with a first factor K, from which a lateral acceleration _quantity a _{yK, n is} determined.

In 5 the qualitative course of the first factor K is shown as a function of the calculated lateral acceleration a _{y, calc, n} . Depending on the vehicle longitudinal speed ν _x , or even vehicle longitudinal speed ranges arise different courses for the first factor K over the calculated lateral acceleration a _{y, calc, n} . As the calculated lateral acceleration a _{y, calc, n} increases, the first factor K asymptotically approaches a maximum value K _max which assumes the same value for all vehicle longitudinal velocities ν _x or vehicle longitudinal speed ranges and wherein this value is ≥ 1.

In a fifth block 34 For the determination of a scaled vehicle longitudinal velocity ν _xA, the vehicle longitudinal velocity ν _{x is} scaled by a second factor A. The second factor A, as in 6 can assume a value between a minimum value A _min and a maximum value A _max .

As the longitudinal vehicle speed ν _x decreases, the second factor A below a lower speed threshold v _u asymptotically approaches or corresponds to the minimum value A _min . Furthermore, the second factor A above an upper speed threshold value v _o asymptotically approaches the maximum value A _max or corresponds to it with increasing vehicle longitudinal speed v _x . By way of example, the lower speed threshold v _u is 80 km / h and the upper speed threshold v _o is 140 km / h. For example, the minimum value A _min = 1 and the maximum value A _max = 1.5 can be selected.

Like from the 4 can be seen, a damper speed ν _{D, n is} determined and taken into account directly in the determination of the damper target force F _{soll, n} . The damper speed ν _{D, n} is further in a sixth block 35 is scaled by a third factor L, forming a scaled damper velocity v _DLn .

As in 7 3, the third factor L has two values depending on the damper speed ν _{D, n} , namely a tensile and a pressure step value, wherein at damper speeds ν _{D, n} greater than zero the rebound step value and at damper velocities ν _{D, n} less than zero the compression step value is used as the authoritative size. Furthermore, tensile and compressive stage values are constant quantities whose factors can vary within a range from a minimum L _min to a maximum L _max , where the maximum L _max = 1 can be chosen and thus L _min <1.

By the multiplicative connection of the built-up attenuation quantity d _m with the scaled vehicle longitudinal velocity ν _xA and the lateral acceleration _magnitude a _{yK, n} as well as the damper velocity ν _{D, n} and the scaled damper velocity v _DLn is in a seventh block 36 for the respective spring element 4 optimal damper target force F _{soll, n} from the arithmetic unit 5 calculated. Depending on the relevant damper target force F _{soll, n} is in a last block 37 an electrical valve control current I _{valve, n,} which generates the corresponding damper valve 4a the respective damper element 4 controls and adjusts accordingly. This determination of the damper target force F _{soll, n} and of the associated star current I _{valve, n} takes place for each of the damper elements 4 of the vehicle individually.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19940198 C1 [0002]

Claims (22)

Method for calculating a damper target force (F _{soll, n} ) for an adjustable damper element ( 4 ) of a spring-damper system, the vehicle body of a vehicle relative to the vehicle wheels ( 2 ) of the vehicle is resiliently and damping supported, wherein a the damper element ( 4 ) associated spring element ( 3 ) has a variable spring stiffness (c _n ) and the damper target force (F _{soll, n} ) is determined depending on the variable spring stiffness (c _n ), characterized in that a lateral acceleration _variable (a _{yK , n} ), the damper target force (F _{soll, n} ) being determined as a function of the lateral acceleration _variable (a _{yK, n} ). Method according to claim 1, characterized in that each vehicle wheel ( 2 ) a damper element ( 4 ) and for each damper element ( 4 ) a damper target force (F _{soll, n} ) is determined separately. The method of claim 1 or 2, characterized in that the damper setpoint force (F _{soll, n)} proportional to the transverse acceleration variable (a _{yK, n)} depends. Method according to one of claims 1 to 3, characterized in that the transverse acceleration _quantity (a _{yK, n} ) based on a vehicle based on the longitudinal velocity (ν _x ) and a steering angle (α) calculated lateral acceleration (a _{y, calc, n} ) determined becomes. A method according to claim 4, characterized in that for the calculation of the damper target force (F _{soll, n} ) on a damper element ( 4 ) each on this damper element ( 4 ), the calculated calculated lateral acceleration (a _{y, calc, n} ) is used. Method according to claim 4 or 5, characterized in that the calculated lateral acceleration ( _{ay, calc, n} ) is scaled by means of a first factor (K) and from this the lateral acceleration _variable ( _{ayK, n} ) is determined. A method according to claim 6, characterized in that the lateral acceleration-dependent first factor (K) is additionally predetermined depending on the vehicle longitudinal speed (ν _x ) or vehicle longitudinal speed ranges. A method according to claim 6 or 7, characterized in that the lateral acceleration-dependent first factor (K) with increasing calculated lateral acceleration (a _{y, calc, n} ) asymptotically approaches a maximum value of the first factor (K _max ), in particular for all longitudinal vehicle speeds (ν _x ) or vehicle longitudinal speed ranges is equal. Method according to one of claims 1 to 8, characterized in that the vehicle longitudinal speed (ν _x ) via a second factor (A) scales and from a scaled vehicle longitudinal velocity (v _xA ) is determined. A method according to claim 9, characterized in that the scaled vehicle longitudinal velocity (v _xA ) is used to calculate the damper target force (F _{soll, n} ), the damper target force (F _{soll, n} ) being determined, in particular, proportionally to the scaled vehicle longitudinal velocity (v _xA ). A method according to claim 9 or 10, characterized in that the second factor (A) assumes a value between a minimum value of the second factor (A _min ) and a maximum value of the second factor (A _max ). Method according to claim 11, characterized in that the second factor (A) below a lower speed threshold value (v _u ) corresponds to the minimum value of the second factor (A _min ) or with decreasing vehicle longitudinal speed (v _x ) corresponds to the minimum value of the second factor ( A _min ) in particular approaches asymptotically. A method according to claim 11 or 12, characterized in that the second factor (A) above an upper speed threshold (v _o ) corresponds to the maximum value of the second factor (A _max ) or with increasing vehicle longitudinal speed (v _x ) the maximum value of the second Factor (A _max ) in particular approaches asymptotically. Method according to one of claims 1 to 13, characterized in that a damper speed (ν _{D, n} ) is determined and taken into account in the determination of the damper target force (F _{soll, n} ). A method according to claim 14, characterized in that the damper target force (F _{soll , n} ) depends proportionally on the damper speed (ν _{D, n} ). Method according to claim 14 or 15, characterized in that the damper speed (ν _{D, n} ) is scaled by a third factor (L) and from this a scaled damper speed (v _DLn ) is determined. Method according to claim 16, characterized in that the third factor (L) has a rebound rate value for a damper speed (ν _{D, n} ) greater than zero and having a pressure step value different from the rebound step value for a damper speed (ν _{D, n} ) smaller than zero, the rebound step value and / or the pressure step value being particularly constant. Method according to Claim 16, characterized in that the damper target force (F _{soll, n} ) is determined as a function of the scaled damper speed (v _DLn ), the damper _{target force} (F _{soll, n} ) depending _, in particular, proportionally on the scaled damper speed (v _DLn ). Method according to one of claims 1 to 18, characterized in that on the basis of the variably predetermined spring stiffness (c _n ) a wheel-related damping amount (d _Rad ) is calculated. A method according to claim 19, characterized in that on the basis of the wheel-related damping amount (d _Rad ) with the aid of a spring-damper system-dependent translation (i) a built-up attenuation quantity (d _m ) is calculated. Device for calculating a damper target force (F _{soll, n} ) for an adjustable damper element ( 4 ) a spring-damper system, which supports the vehicle body of a vehicle relative to the vehicle wheels of the vehicle resiliently and damping, wherein the damper element ( 4 ) associated spring element ( 3 ) has a variable spring stiffness (c _n ), and wherein an arithmetic unit determines the damper target force (F _{soll, n} ) as a function of the variable spring stiffness (c _n ), characterized in that the arithmetic unit ( 5 ) a lateral acceleration _variable (a _{yK, n} ) describing the lateral acceleration (a _{y, calc, n} ) and the damper _{target force} (F _{soll, n} ) are determined as a function of the lateral acceleration _variable (a _{yK, n} ). Apparatus according to claim 21, characterized in that it is in the spring element ( 3 ) around a gas spring element ( 3 ) with variable spring stiffness (c _n ), wherein in particular more than one valve arrangement ( 12 . 14 . 16 ) fluidly interconnectable and fluidically separable gas spaces ( 7 . 8th . 9 . 10 ) are provided.