Ultrasonic liquid level gauge for tanks subject to movement and vibration
First Claim
1. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
- an ultrasonic transducer mounted on the bottom of the vessel;
an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses;
means for processing said received echoes to determine a center of a distribution of the received echoes as a function of time; and
means for determining a liquid level height based on a velocity of the ultrasonic pulses in said liquid and a time of said center of said distributionwherein said means for determining performs an averaging of two of echo arrival times within a predetermined time interval to determine said liquid level height, independent of an amplitude of said echoes.
2 Assignments
0 Petitions
Accused Products
Abstract
One or more high-frequency ultrasonic transducers are used to measure the liquid level of tanks containing any type of fluid, but fuel in particular. The invention relates specifically to tanks that are subject to movement and vibration which generally makes the use of ultrasonic echoes unreliable for obtaining accurate level measurements. A special algorithm is used to obtain the temporal center of the distribution of echo arrival times over a preset time interval. From this temporal center of an echo distribution, the liquid level is readily obtained through the acoustic velocity, time and distance relationship. An annular piezoelectric plate, independently driven at low ultrasonic frequencies (kHz range), mounted on the tank bottom surrounds the high frequency ultrasonic transducer. The function of the piezoelectric plate is to send out propagating ultrasonic waves (essentially longitudinal) to maintain the tank area in the immediate region of the high-frequency transducer free from debris and sediment deposits at the bottom of the tank thereby avoiding the uncertainty in the measurement that is introduced by debris on the tank bottom.
161 Citations
31 Claims
-
1. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
-
an ultrasonic transducer mounted on the bottom of the vessel; an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses; means for processing said received echoes to determine a center of a distribution of the received echoes as a function of time; and means for determining a liquid level height based on a velocity of the ultrasonic pulses in said liquid and a time of said center of said distribution wherein said means for determining performs an averaging of two of echo arrival times within a predetermined time interval to determine said liquid level height, independent of an amplitude of said echoes. - View Dependent Claims (3, 4, 5, 6, 7)
-
-
2. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
-
an ultrasonic transducer mounted on the bottom of the vessel; an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses; means for processing said received echoes to determine a center of a distribution of the received echoes as a function of time; means for determining a liquid level height based on a velocity of the ultrasonic pulses in said liquid and a time of said center of said distribution; and a second low frequency transducer mounted circumferentially about said ultrasonic transducer, said low frequency transducer emitting low frequency acoustic waves to maintain a clean tank surface.
-
-
8. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
-
an ultrasonic transducer mounted on the bottom of the vessel; an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses; a second independently driven, low frequency transducer mounted circumferentially about said ultrasonic transducer, said low frequency transducer emitting low frequency acoustic waves to maintain a clean tank surface; and means for determining a liquid level height based on a velocity of the ultrasonic pulses in said liquid and a time of a center of a distribution. - View Dependent Claims (9, 10, 11, 12, 13)
-
-
14. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
-
a plurality of ultrasonic transducers mounted on the bottom of the vessel; an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses means for processing said received echoes to determine a center of a distribution of the received echoes as a function of time; and means for determining a liquid level height based on a velocity of the ultrasonic pulses in said liquid and a time of said center of said distributions, wherein said means for determining performs an averaging of two of echo arrival times within a predetermined time interval to determine said liquid level height, independent of an amplitude of said echoes. - View Dependent Claims (16, 17, 18, 21, 26, 27, 28)
-
27. The system of claim 26 wherein said means for determining includes means for determining an ultrasonic velocity of said pulses in said liquid as a function of temperature.
-
28. The system of claim 27 wherein said means for determining further includes means for calculating said liquid level height in accordance with ##EQU6## where v(T) is the ultrasonic velocity in said liquid as a function of temperature and Δ
- t is a round trip travel time of said pulses in the vessel wall where
space="preserve" listing-type="equation">Δ
t=2D/v.sub.Cand D is a thickness of the vessel wall and VD is the velocity of the ultrasonic pulses in the vessel wall.
- t is a round trip travel time of said pulses in the vessel wall where
-
-
15. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
-
a plurality of ultrasonic transducers mounted on the bottom of the vessel; an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses; means for processing said received echoes to determine a center of a distribution of the received echoes as a function of time; means for determining a liquid level height based on a velocity of the ultrasonic pulses in said liquid and a time of said center of said distribution; and a plurality of second low frequency transducers mounted circumferentially about said ultrasonic transducers, said low frequency transducers emitting low frequency acoustic waves to maintain a clean tank surface. - View Dependent Claims (19, 20, 22, 23, 24, 25)
-
-
29. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
-
an ultrasonic transducer mounted on the top of the vessel; an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses; means for processing said received echoes to determine a center of a distribution of the received echoes as a function of time; and means for determining a liquid level height based on a velocity of the ultrasonic pulses and a time of said center of said distribution, wherein said means for determining performs an averaging of two of echo arrival times within a predetermined time interval to determine said liquid level height, independent of an amplitude of said echoes. - View Dependent Claims (31)
-
-
30. An ultrasonic echo system for measuring and determining a height of a liquid in a storage vessel, said system comprising:
-
an ultrasonic transducer mounted on the top of the vessel; an ultrasonic pulse unit for causing said transducer to emit ultrasonic pulses and for receiving echoes of said ultrasonic pulses; means for processing said received echoes to determine a center of a distribution of the received echoes as a function of time; and means for determining a liquid level height based on a velocity of the ultrasonic pulses and a time of said center of said distribution; and a second low frequency transducer mounted circumferentially about said ultrasonic transducer, said low frequency transducer emitting low frequency acoustic waves to maintain a clean top tank surface.
-
Specification