Method and device for determining a liquid level with the aid of ultrasonic pulses
First Claim
1. A method for determining a liquid level in a container from an echo time measurement, which comprises:
- measuring respective reference sound velocities along at least two reference paths located in a liquid;
determining a characteristic of a mean sound velocity in the vertical direction up to the liquid level by extrapolation from the reference sound velocities; and
using the characteristic to determine the mean sound velocity in the vertical direction averaged up to the liquid level, and determining the height to the liquid level by correlating an echo time of ultrasonic pulses reflected at a liquid surface at the liquid level with the mean sound velocity averaged up to the liquid level.
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Accused Products
Abstract
A method for determining a liquid level with the aid of ultrasonic pulses improves the measuring accuracy of the liquid level in a container with an echo time measurement of ultrasonic pulses and a mean sound velocity. The mean sound velocity is extrapolated from at least two reference sound velocities in the liquid. In this way it is possible to achieve a measuring accuracy of less than a millimeter, independently of the liquid level. A device for carrying out the method has a main measuring path, at least one device for transmitting and receiving ultrasonic pulses, at least two reference paths for determining sound velocities, and a computer unit. The computer unit extrapolates from the sound velocities to the mean sound velocity.
27 Citations
16 Claims
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1. A method for determining a liquid level in a container from an echo time measurement, which comprises:
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measuring respective reference sound velocities along at least two reference paths located in a liquid;
determining a characteristic of a mean sound velocity in the vertical direction up to the liquid level by extrapolation from the reference sound velocities; and
using the characteristic to determine the mean sound velocity in the vertical direction averaged up to the liquid level, and determining the height to the liquid level by correlating an echo time of ultrasonic pulses reflected at a liquid surface at the liquid level with the mean sound velocity averaged up to the liquid level. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In a device for determining a liquid level in a container from an echo time measurement, the improvement comprising:
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a main measuring path and at least two reference paths;
at least one transducer device located at one end of said main measuring path and at one end of said at least two reference paths for transmitting and receiving ultrasonic pulses;
said at least two reference paths having at least one reflector device located in the liquid for determining respective reference sound velocities between said at least one transducer device and said at least one reflector device located in the liquid along said at least two reference paths; and
a computer unit for determining a characteristic of a mean sound velocity in the vertical direction up to a liquid level by extrapolation from the reference sound velocities of said at least two reference paths, said computer unit determining the liquid level from the echo time of the ultrasonic pulses reflected at a liquid surface and the mean sound velocity in the vertical direction up to said liquid level. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification