Method of controlling the quantity of air in a vehicle level control system

• US 20030107191A1
• Filed: 12/11/2002
• Published: 06/12/2003
• Est. Priority Date: 12/11/2001
• Status: Active Grant

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: DaimlerChrysler AG (Mercedes-Benz Group AG)
• Inventors: Romer, Matthias, Sprengel, Thomas, Scheerer, Hans, Schweickhardt, Frank
• Granted Patent: US 6,845,988 B2
• Time in Patent Office: Days
• US Class Current: 280/5.514
• CPC Class Codes: B60G 17/052 Pneumatic spring characteristics B60G17/048 takes precedence ; valves per se F16K
• CPC Class Codes: B60G 17/0523 Regulating distributors or valves for pneumatic springs
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/51222 Pneumatic
• CPC Class Codes: B60G 2400/8422 of air
• CPC Class Codes: B60G 2500/2014 Closed systems

Abstract

In a process for controlling the quantity of air in a closed, chargeable and emptiable pneumatic level control system of a vehicle, which level control system comprises at least one pressure sensor, one pump, an actuator, a storage reservoir and pressure lines interconnecting these components, at least one vehicle body level sensor, and a temperature sensor, which measures the ambient temperature, from the values measured an air mass of the level control system is calculated on the basis of the air pressures in the components, the level of the vehicle and the ambient temperature. Furthermore, the level of the vehicle, the ambient temperature and a maximum possible change in level from a particular vehicle level are used to calculate a vehicle-specific desired air mass and a desired air pressure in the system. The air mass is increased if the actual air pressure drops below the desired air pressure, and the air mass is reduced if the actual air pressure exceeds the desired air pressure.

Claims

1. A method of controlling the quantity of air in a closed, chargeable and emptiable pneumatic level control system of a vehicle, which level control system comprises at least one pressure sensor, one pump, at least one actuator, at least one storage reservoir and circuitry interconnecting these components, at least one level sensor, and a pressure sensor measuring the air pressure in the individual components of the level control system, said method comprising the steps of:

providing a temperature sensor (63) which measures the ambient temperature around the vehicle,

calculating the air mass of the level control system from the air pressures in the individual components (40, 50), the actual level of the vehicle and the ambient temperature,

calculating a vehicle-specific desired air mass and a desired air pressure from the desired level of the vehicle, the ambient temperature and the maximum possible change in level from the actual vehicle level,

increasing the air mass in the level control system if the actual air pressure is below the desired air pressure, and

reducing the air mass in the level control system if the actual air pressure exceeds the desired air pressure.

2. A process according to claim 1, wherein the temperature determination and the quantity of air control take place in the level control system after vehicle operation has been started.

3. A process according to claim 1, wherein in the event of a low level emergency, the pump (20) pumps ambient air directly into the actuators (50) while the level adjustment is being performed.

4. A process according to claim 1, wherein, in the event of a high level emergency, the level control system discharges air from the actuators (50) into the environment.

5. A process according to claim 1, wherein the level control system diagnoses a leak in the event of differences between two successive air mass determinations.

6. A process according to claim 1, wherein dynamic driving parameters are additionally evaluated for the determination of the required or permissible air mass.

7. A process according to claim 1, wherein driver-specific parameters are additionally evaluated for the determination of the required or permissible air mass.

8. A process according to claim 1, wherein, for determining the system pressure, only one central pressure sensor is used for the whole level control system.