Method for controlling the level of a vehicle body of a motor vehicle

A method for controlling the level of a vehicle body of a motor vehicle with a level control system having a plurality of actuator elements with which the level of the vehicle body can be lowered by discharging an actuating means from said actuator elements, the level control system including a control unit and the motor vehicle being subjected to wheel contact forces, the method comprising the steps of:

• determining a first level of said vehicle body relative to a reference point directly before a discharge operation;
• initiating a discharge operation of said vehicle body when said first level lies above a pregiven level;
• after initiating a discharge operation, checking in said control unit as to whether said vehicle body has lowered from said first level in accordance with an input;
• interrupting said discharge operation when said vehicle body has not lowered from said first level in accordance with said input;
• after a time span, a check is made in time intervals as to whether, during one of the time intervals, said vehicle body has lowered at least by a pregiven amount from said first level and whether the wheel contact forces have remained at least almost constant;
• and,
• the control unit interrupts said discharge operation when said vehicle has not lowered at least by said pregiven amount from said first level and when said wheel contact forces have not remained at least almost constant.

A method for controlling the level of a vehicle body of a motor vehicle with a level control system having a plurality of actuator elements with which the level of the vehicle body can be lowered by discharging an actuating means from said actuator elements, the level control system including a control unit and the method comprising the steps of:

• determining a first level of said vehicle body relative to a reference point directly before a discharge operation;
• initiating a discharge operation of said vehicle body when said first level lies above a pregiven level;
• after initiating a discharge operation, checking in said control unit as to whether said vehicle body has lowered from said first level in accordance with an input;
• interrupting said discharge operation when said vehicle body has not lowered from said first level in accordance with said input;
• wherein said discharge operation is immediately interrupted when said control unit determines that the actual value of a predetermined vehicle parameter is less than a pregiven value for this vehicle parameter;
• checking, as a vehicle parameter, at least one wheel contact force;
• and,
• interrupting said discharge operation when said at least one wheel contact force is less than a minimum wheel contact force which is so pregiven that said minimum wheel contact force is generated by said vehicle body even with minimum loading.

A method for controlling the level of a vehicle body of a motor vehicle with a level control system having a plurality of actuator elements with which the level of the vehicle body can be lowered by discharging an actuating means from said actuator elements, the level control system including a control unit and the method comprising the steps of:

• determining a first level of said vehicle body relative to a reference point directly before a discharge operation;
• initiating a discharge operation of said vehicle body when said first level lies above a pregiven level;
• after initiating a discharge operation, checking in said control unit as to whether said vehicle body has lowered from said first level in accordance with an input;
• interrupting said discharge operation when said vehicle body has not lowered from said first level in accordance with said input;
• wherein said level control system includes at least one air spring with which said vehicle body is spring suspended;
• and, pressurized air is discharged from said air spring during a discharge operation;
• discharging air from said air spring maximally over a time span until there is a drop below a minimal air pressure in said air spring which is so pregiven that said vehicle body, even with minimum load, would have had to lower from said first level in accordance with the input;
• during said time span, checking as to whether said vehicle body has lowered from said first level in accordance with said input;
• and,
• said control unit interrupting said discharge operation when said vehicle body has not lowered from said first level in accordance with said input up to the end of said time span.

A method for controlling the level of a vehicle body of a motor vehicle with a level control system having a plurality of actuator elements with which the level of the vehicle body can be lowered by discharging an actuating means from said actuator elements, the level control system including a control unit and the method comprising the steps of:

• determining a first level of said vehicle body relative to a reference point directly before a discharge operation;
• initiating a discharge operation of said vehicle body when said first level lies above a pregiven level;
• after initiating a discharge operation, checking in said control unit as to whether said vehicle body has lowered from said first level in accordance with an input;
• interrupting said discharge operation when said vehicle body has not lowered from said first level in accordance with said input;
• wherein temporarily, exclusively a lifting operation of the vehicle body can be initiated after an interruption of a discharge operation with the engine of the motor vehicle switched on;
• and,
• wherein the discharge operation of the vehicle body can only then be initiated again when the speed of the motor vehicle has exceeded a limit value or when, after a switch off of the ignition, a renewed switch-on of the ignition takes place.