Method and apparatus for measuring the content of a storage vessel

• US 5,309,760 A
• Filed: 08/12/1991
• Issued: 05/10/1994
• Est. Priority Date: 07/07/1988
• Status: Expired due to Fees

• Current Assignee: Kanto Seiki Company Limited
• Original Assignee: Kanto Seiki Company Limited
• Inventors: Ohneda, Katushi, Watanabe, Kajiro
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US07/743,515
• Time in Patent Office: 1,002 Days
• Field of Search: 73/149, 364/564
• US Class Current: 73/149
• CPC Class Codes: G01F 23/14 by measurement of pressure
• CPC Class Codes: G01F 23/18 Indicating, recording or alarm devices actuated electrically

Abstract

The peak amplitude values of two different frequency pressure changes produced by the displacement device of a volume sensing arrangement, are obtained and one divided by the other to produce a value indicative of the volume of the unfilled portion of a storage vessel. The contents of the vessel are derived by subtracting the unfilled volume from the vessel capacity. In the embodiments wherein a single pressure sensor is used, the signal is simultaneously filtered with a low pass filter and a band pass filter in order to obtain static and dynamic pressure data. In some embodiments the single sensor is disposed in a chamber in which the displacement means produces two different frequency pressure variations. The chamber is communicated with the storage vessel by a pipe the length and diameter of which are selected to prevent the pressure variations produced by one of the frequencies from being transmitted therethrough. In other embodiments two pressure sensors are used and the special pipe dispensed with and the outputs of the two sensors fed individually to band pass filters.

Claims

1. A measuring arrangement comprising:

a vessel of known volume;

an air bleed, said air bleed providing restricted fluid communicating between the interior of said vessel and the atmosphere;

means defining a chamber;

a displacement device disposed in said chamber, said displacement device being arranged to vary the pressure in said chamber, said displacement device dividing said chamber into first and second portions, the first portion being enclosed within said chamber and said second portion being fluidly communicated with the interior of said vessel;

means providing a limited amount of fluid communication between the first portion of said chamber and the interior of said vessel;

a first pressure sensor, said pressure sensor being responsive to the pressure in the first portion of said chamber and arranged to produce a first output indicative thereof;

a second pressure sensor, said second pressure sensor being responsive to the pressure in said vessel and arranged to produce a second output indicative thereof;

circuit means for receiving the outputs of said first and second pressure sensors and for filtering out first and second data, respectively, said circuit means including means for processing the first and second data in a manner which produces a signal indicative of the contents of said vessel.

2. A device as claimed in claim 1 wherein said displacement device comprises a diaphragm, said diaphragm partitioning said chamber into the first and second portions.

3. A device as claimed in claim 2 wherein said means for providing a limited communication between the first portion of the chamber and the interior of the vessel comprises a passage which includes an orifice.

4. A device as claimed in claim 2 wherein said second portion has an open end which provides unrestricted communicated between the second portion and interior of said vessel.

5. A method of measuring the contents of a vessel, comprising the steps of:

permitting restricted fluid communication between the interior of the vessel and the ambient atmosphere by way of an air bleed;

energizing a displacement device which is disposed in a chamber fluidly communicated with the vessel, in a manner which varies the pressure in said chamber and in said vessel;

sensing the pressure in said chamber using a first pressure sensor and producing a first output indicative thereof;

sensing the pressure in said vessel using a second pressure sensor and producing a second output indicative thereof;

filtering the first and second outputs to obtain first and second pieces of information; and

processing the first and second pieces of information in a manner which produces a signal indicative of the contents of said vessel.