Electronic level control device for air-suspended vehicles, method and control device for electronic level control
AssigneeWABCO Europe BVBA
InventorsDirk Bormann, Jens Gröger, Marek Swoboda
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Abstract
Disclosed is an electronic level control device for a vehicle having an air suspension system, for example a trailer vehicle having an air suspension system, the vehicle comprising a chassis having an axle and at least two wheels arranged on the axle, wherein an air spring is arranged between the axle and the chassis for at least one of the wheels, wherein an electronic control unit can initiate a level controlling procedure by actuating a solenoid valve, and wherein at least one capacitive level sensor is provided for the axle. The distance between the chassis and the at least one axle can be determined by the level sensor.
Claims11
An electronic level control device for a vehicle having an air suspension system, said vehicle comprising a chassis having at least one axle, at least two wheels arranged on the at least one axle, and an air spring arranged between the at least one axle and the chassis for at least one of the at least two wheels, the electronic level control device comprising:
- an electronic control unit configured to initiate a level controlling procedure by actuating a solenoid valve of the air spring to supply compressed air to the air spring from a compressed air storage device and/or discharge compressed air from the air spring into the atmosphere so as to perform the level controlling procedure;
- and
- at least one capacitive level sensor comprising a variable capacitance, wherein said capacitive level sensor is configured to determine a distance between the chassis and the at least one axle based on the variable capacitance, the at least one capacitive level sensor further comprising a capacitor formed by the chassis and the at least one axle, wherein the variable capacitance varies depending upon the distance between the chassis and the at least one axle;
- and
- the electronic control unit including an electric circuit comprising a DC voltage source, a charging resistor, and a time-voltage measuring unit,
- wherein the electric circuit is configured to:
- generate a square wave voltage:
- determine a time period that elapses between applying the square wave voltage and achieving a predetermined charging voltage value at the capacitor, and calculate a current capacitance of the capacitor by the formula:
- C2=(R1/Δt−1/C1)−1 wherein C2 is the current capacitance of the capacitor, R1 is a previously known electrical resistance of the charging resistor, Δt is the determined time period, and C1 is a constant capacitance of other capacitive elements connected in series to the capacitor, and wherein the electronic control unit is configured to generate a control signal for actuating the solenoid valve based on a value of the variable capacitance and wherein variable capacitance is the calculated current capacitance of the capacitor (C2).
A method for electronic level control of a vehicle having an air suspension system, said vehicle comprising a chassis having at least one axle, two wheels arranged on the at least one axle, and an air spring for at least one of the wheels arranged between the at least one axle and the chassis, the method comprising:
- initiating, by an electronic control unit, a level controlling procedure comprising one of:
- supplying compressed air to the air spring from a compressed air storage device;
- or discharging compressed air from the air spring into the atmosphere;
- determining a capacitance of a capacitor, said capacitance being variable in dependence upon a distance between the at least one axle and the chassis, wherein the chassis together with the at least one axle forms the capacitor;
- generating a square wave voltage by an electric circuit, wherein the electric circuit comprises a DC voltage source, a charging resistor, and a time-voltage measuring unit;
- and determining, using the electric circuit, a time period that elapses between applying the square wave voltage and achieving a predetermined charging voltage value at the capacitor;
- wherein determining the capacitance of the capacitor comprises calculating a current capacitance of the capacitor by the formula:
- C2=(R1/Δt−1/C1)−1 wherein C2 is the current capacitance of the capacitor, R1 is a previously known electrical resistance of the charging resistor, Δt is the determined time period, and C1 is a constant capacitance of other capacitive elements connected in series to the capacitor and generating a control signal for actuating a solenoid valve to initiate the level controlling procedure based on the determined current capacitance of the capacitor (C2).
Dependencies are inferred from the claim text.