METHOD AND APPARATUS FOR DETERMINING THE FLOW PARAMETERS OF A STREAMING MEDIUM
First Claim
1. A method for determining the flow parameters of a streaming gas in a conduit for medical applications the method comprising the steps of:
- generating longitudinal waves inside the conduit with a transducer,transmitting said longitudinal waves in two different cross directions relative to the streaming direction (upstream and downstream direction) through the conduit,receiving said waves with transducers,determining transit time values of the waves between the transducer used as a transmitter and the transducers used as receivers,generating a difference value on the basis of the determined transit time values, anddetermining the flow parameters of the streaming gas on the basis of said difference value,characterized in, the method further includes the steps of;
determining a first pair of transit time values of the waves between the transducer used as a transmitter and the transducers used as receivers,determining an approximate flow rate of the streaming gas on the basis of a difference between the first pair of transit time values and the transit times corresponding to a zero flow rate,determining a time shift value necessary for the streaming gas to propagate from a first wave transmission path to a second wave transmission path,determining a second pair of transit time values of the waves between the transducer used as a transmitter and the transducers used as receivers with a delay between the upstream and downstream transmission path transit time measurements, the delay being determined by said time shift value, anddetermining a more accurate flow rate of the streaming gas on the basis of a difference between the second pair of transit time values.
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Accused Products
Abstract
According to the method longitudinal waves are generated in a transducer used only as a transmitter connected from outside to a conduit. These waves are transmitted along two diagonal paths through the streaming medium in an upstream and a downstream direction, and received by two transducers used only as receivers which are located in a diagonal upstream and downstream position and on an opposite side relative to the transducer used as a transmitter, also connected to the conduit. A transit time value of the waves between the transducer used as a transmitter and each of the transducers used as receivers is determined. A difference value on the basis of the determined transit time values is generated and the flow parameters are determined on the basis of said difference value. This measuring method is highly independent of the propagation velocity of the wave in the medium streaming in the conduit therefore also independent of the temperature and humidity of a gaseous medium. An apparatus and a conduit for use in the apparatus for performing the method is also suggested. The conduit used in the apparatus comprises a first location for receiving a transmitter in a middle region of the measuring area and two second locations for receiving receivers in a border region of the measuring area opposite to the first location. The wall of the conduit is dimensioned so that the longitudinal waves can pass through it with minimal loss and maximum efficiency. The inner wall of the conduit forms a uniform and continuos surface for the transmission of the longitudinal waves between the transmitter and the receivers and for blocking the passage of any organic or inorganic material. In medical applications the apparatus and its housing is configured to receive, hold and release a sterile conduit.
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Citations
21 Claims
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1. A method for determining the flow parameters of a streaming gas in a conduit for medical applications the method comprising the steps of:
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generating longitudinal waves inside the conduit with a transducer, transmitting said longitudinal waves in two different cross directions relative to the streaming direction (upstream and downstream direction) through the conduit, receiving said waves with transducers, determining transit time values of the waves between the transducer used as a transmitter and the transducers used as receivers, generating a difference value on the basis of the determined transit time values, and determining the flow parameters of the streaming gas on the basis of said difference value, characterized in, the method further includes the steps of; determining a first pair of transit time values of the waves between the transducer used as a transmitter and the transducers used as receivers, determining an approximate flow rate of the streaming gas on the basis of a difference between the first pair of transit time values and the transit times corresponding to a zero flow rate, determining a time shift value necessary for the streaming gas to propagate from a first wave transmission path to a second wave transmission path, determining a second pair of transit time values of the waves between the transducer used as a transmitter and the transducers used as receivers with a delay between the upstream and downstream transmission path transit time measurements, the delay being determined by said time shift value, and determining a more accurate flow rate of the streaming gas on the basis of a difference between the second pair of transit time values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 17, 18, 19, 20)
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9. A conduit for use in a medical apparatus for determining the flow parameters of a gas streaming in the conduit, the conduit comprising
open end sections and a measuring section between end sections of the conduit, a first location in a middle region of the measuring section for receiving a transducer used for generating longitudinal waves inside the conduit and for transmitting said longitudinal waves in two different cross directions relative to the streaming direction (upstream and downstream direction) through the conduit, and two second locations in a border region of the measuring section opposite to the first location for receiving transducers used for receiving said waves, characterized in, that the end sections have a substantially circular cross section and the measuring section has a substantially rectangular cross section with narrow side walls and wide side walls, wherein the transducers are connected to the narrow side walls, and the inner wall of the conduit forms a continuous surface with respect to the streaming gas.
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21-25. -25. (canceled)
Specification