Method and control device for adjusting the damping force of a shock absorber

A method for adjusting a damping force of shock absorbers connected between a vehicle body and a wheel at vehicle corners of a motor vehicle, the method comprising the steps of:

• determining at least one damping force (FLIFT, FPITCH, FROLL), which is referred to a center of gravity of a vehicle body, and which is divided between shock absorbers of the respective wheels of the motor vehicle as a function of at least one variable which represents a movement of the vehicle body or a movement of the respective wheel,
• determining, for at least one of the lifting, pitching and rolling modal directions, the respective damping force (FLIFT, FPITCH, FROLL) as a function of a predefined, constantly maintained degree of damping of the respective modal direction,
• wherein for the pitching modal direction, the degree of damping is kept constant in such a way that a damping constant for the pitching modal direction is adapted as a function of a changing pitching-spring stiffness or a changing pitching moment of mass inertia of the motor vehicle, with the result that the degree of damping for the pitching modal direction remains constant, and
• wherein the damping constant dPITCH for the pitching modal direction is adapted in such a way that the degree of damping DPITCH remains constant and according to the equation:
• D
• PITCH
• =
• d
• PITCH
• 2
• ⁢
• c
• PITCH
• ⁢
• J
• PITCH
• ,
• where
• DPITCH is the degree of damping for the pitching modal direction,
• dPITCH is the damping constant for the pitching modal direction,
• cPITCH is the pitching-spring stiffness, and
• JPITCH is the pitching moment of mass inertia.

A method for adjusting a damping force of shock absorbers connected between a vehicle body and a wheel at vehicle corners of a motor vehicle, the method comprising the steps of:

• determining at least one damping force (FLIFT, FPITCH, FROLL), which is referred to a center of gravity of a vehicle body, and which is divided between shock absorbers of the respective wheels of the motor vehicle as a function of at least one variable which represents a movement of the vehicle body or a movement of the respective wheel,
• determining, for at least one of the lifting, pitching and rolling modal directions, the respective damping force (FLIFT, FPITCH, FROLL) as a function of a predefined, constantly maintained degree of damping of the respective modal direction,
• wherein, for the rolling modal direction, the degree of damping is kept constant in such a way that a damping constant for the rolling modal direction is adapted as a function of a changing rolling-spring stiffness or a changing rolling-moment of mass inertia of the motor vehicle, with the result that the degree of damping for the rolling modal direction remains constant, and
• wherein the damping constant dROLL for the rolling modal direction is adapted in such a way that the degree of damping DROLL remains constant and according to the equation:
• D
• ROLL
• =
• d
• ROLL
• 2
• ⁢
• c
• ROLL
• ⁢
• J
• ROLL
• ,
• wherein
• DROLL is the degree of damping for the rolling modal direction,
• dROLL is the damping constant for the rolling modal direction,
• cROLL is the rolling-spring stiffness, and
• JROLL is the rolling moment of mass inertia.

A control device for adjusting a damping force of shock absorbers which are connected between a vehicle body and a respective wheel at vehicle corners of the motor vehicle, wherein said control device is configured to:

• determine at least one damping force (FLIFT, FPITCH, FROLL), which is referred to a center of gravity of the vehicle body, and which is divided between the shock absorbers of the respective wheels of the motor vehicle as a function of at least one variable which represents a movement of the vehicle body or a movement of the respective wheel, and
• determine, for at least one of the lifting, pitching and rolling modal directions, the respective damping force (FLIFT, FPITCH, FROLL) as a function of a predefined, constantly maintained degree of damping of the respective modal direction,
• wherein, for the lifting modal direction, the degree of damping for the lifting modal direction is kept constant, in that a damping constant for the lifting modal direction is adapted as a function of a changing lifting-spring stiffness or changing mass of the motor vehicle, with the result that the degree of damping for the lifting modal direction remains constant, and
• wherein the damping constant dLIFT for the lifting modal direction is adapted in such a way that the degree of damping DLIFT remains constant according to the equation:
• D
• LIFT
• =
• d
• LIFT
• 2
• ⁢
• c
• LIFT
• ⁢
• m
• ,
• where
• DLIFT is the degree of damping for the lifting modal direction,
• dLIFT is the damping constant for the lifting modal direction,
• cLIFT is the lifting-spring stiffness, and
• m is the mass.