Method for determining the fill state in a tank utilizing ultrasonic waves and reference surfaces

A motor vehicle comprising:

• a tank supporting a liquid and defining a tank wall;
• an ultrasonic level sensor supported by the tank, the ultrasonic level sensor comprising:
• a transmitter unit emitting an ultrasonic wave, and
• a receiver unit receiving the emitted ultrasonic wave;
• a calibration component comprising:
• a spring segment;
• a contact surface pressed fixedly on the tank wall by way of the spring segment;
• and
• at least two reference surfaces for reflection of the ultrasonic wave, the at least two reference surfaces include a first reference surface and a second reference surface, wherein the first reference surface is disposed below the second reference surface;
• and
• a controller in communication with the ultrasonic level sensor, the controller determines the level of the liquid in the tank by executing the following steps:
• a) determining a first propagation speed of an ultrasonic wave in the liquid over a first measuring distance from the ultrasonic level sensor to the first reference surface;
• b) determining a second propagation speed of the ultrasonic wave in the liquid over a second measuring distance from the first reference surface to the second reference surface;
• c) measuring a propagation time of the ultrasonic wave from the ultrasonic level sensor to a liquid level of the liquid in the tank;
• d) selecting the first propagation speed or the second propagation speed depending on a first selection criterion, and checking the measured propagation speed as a second selection criterion, wherein the second propagation speed is not selected if the measured propagation time lies outside a time interval corresponding to twice the propagation time to the second reference surface and the first propagation speed was selected for a previous iteration of the method;
• and
• e) computing a level of the liquid with the propagation time measured in step c) and the propagation speed selected in step d).

A method for determining a level of a liquid in a tank, the method comprising:

• providing a tank supporting a liquid, the tank defining a tank wall;
• providing an ultrasonic level sensor supported by the tank, the ultrasonic level sensor having a transmitter unit and a receiver unit;
• emitting, from the transmitter unit an ultrasonic wave;
• receiving, at the receiver unit the emitted ultrasonic wave;
• providing a calibration component, the calibration component comprising:
• a spring segment;
• a contact surface pressed fixedly on the tank wall by way of the spring segment;
• and
• at least two reference surfaces for reflection of the ultrasonic wave, a first reference surface is disposed below a second reference surface;
• providing a controller in communication with the ultrasonic level sensor;
• a) determining, at the controller, a first propagation speed of an ultrasonic wave in the liquid over a first measuring distance from the ultrasonic level sensor to the first reference surface;
• b) determining, at the controller, a second propagation speed of an ultrasonic wave in the liquid over a second measuring distance from the first reference surface to the second reference surface;
• c) measuring, at the controller, a propagation time of an ultrasonic wave from the ultrasonic level sensor to a liquid level of the liquid in the tank;
• d) selecting, at the controller, the first propagation speed or the second propagation speed depending on a first selection criterion;
• and
• e) computing, at the controller, a level with the propagation time measured in step c) and the propagation speed selected in step d) by executing the following substeps:
• i) computing the level based on the selected propagation speed;
• ii) checking whether a level which is determined at the second propagation speed corresponds to twice a height of the second reference surface;
• iii) determining a fluctuation in a second response signal of the second reference surface at the ultrasonic level sensor in a time interval;
• iv) checking whether the fluctuation in the second response signal exceeds a prespecified limit value;
• and
• v) correcting the level which is computed in step i) to the height of the second reference surface when steps ii) and iv) are complete.

A motor vehicle comprising:

• a tank supporting a liquid and defining a tank wall;
• an ultrasonic level sensor supported by the tank, the ultrasonic level sensor comprising:
• a transmitter unit emitting an ultrasonic wave, and
• a receiver unit receiving the emitted ultrasonic wave;
• a calibration component comprising:
• a spring segment;
• a contact surface pressed fixedly on the tank wall by way of the spring segment;
• and
• at least two reference surfaces for reflection of the ultrasonic wave, the at least two reference surfaces include a first reference surface and a second reference surface, wherein the first reference surface is disposed below the second reference surface;
• and
• a controller in communication with the ultrasonic level sensor, the controller determines the level of the liquid in the tank by executing the following steps:
• a) determining a first propagation speed of an ultrasonic wave in the liquid over a first measuring distance from the ultrasonic level sensor to the first reference surface;
• b) determining a second propagation speed of the ultrasonic wave in the liquid over a second measuring distance from the first reference surface to the second reference surface;
• c) measuring a propagation time of the ultrasonic wave from the ultrasonic level sensor to a liquid level of the liquid in the tank;
• d) selecting the first propagation speed or the second propagation speed depending on at least one selection criterion;
• and
• e) computing a level with the propagation time measured in step c) and the propagation speed selected in step d) by executing the following subsets:
• i) computing the level based on the selected propagation speed;
• ii) checking whether a level which is determined at the second propagation speed corresponds to twice a height of the second reference surface;
• iii) determining a fluctuation in a second response signal of the second reference surface at the ultrasonic level sensor in a time interval;
• iv) checking whether the fluctuation in the second response signal exceeds a prespecified limit value;
• and
• v) correcting the level which is computed in step i) to the height of the second reference surface when steps ii) and iv) are complete.