Zero point drift compensating flowmeter

• US 9,689,729 B2
• Filed: 10/09/2013
• Issued: 06/27/2017
• Est. Priority Date: 10/24/2012
• Status: Active Grant

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Inventors: Kosaka, Ryo, Fukuda, Kyouhei, Yamane, Takashi
• Primary Examiner(s): Patel, Harshad R
• Application Number:
  US14/438,197
• Publication Number:
  US 20150253170A1
• Time in Patent Office: 1,357 Days
• Field of Search: None
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: G01F 1/206 Measuring pressure, force or momentum of a fluid flow which is forced to change its direction
• CPC Class Codes: G01F 1/50 Correcting or compensating means
• CPC Class Codes: G01F 1/708 Measuring the time taken to traverse a fixed distance
• CPC Class Codes: G01F 1/72 Devices for measuring pulsing fluid flows
• CPC Class Codes: G01F 1/78 Direct mass flowmeters
• CPC Class Codes: G01F 1/80 operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
• CPC Class Codes: G01F 15/02 Compensating or correcting for variations in pressure, density or temperature
• CPC Class Codes: G01L 13/00 Devices or apparatus for measuring differences of two or more fluid pressure values

Abstract

A small and light-weight flowmeter realizes the compensation of a zero point drift. A mass flowmeter includes: a centrifugal force/centripetal force detection strain gauge adhered to a part acted upon by a centrifugal force or a centripetal force of fluid in a pipe line in which the fluid flows and a flow rate zero point drift compensation strain gauge adhered to a position different from that of the centrifugal force/centripetal force detection strain gauge. A pulse wave propagation time between the two points is used to compensate a zero point drift of a flow rate.

Claims

1. A pressure sensor, comprising:

a first pressure detection device configured to detect the pressure of fluid in a pipe line in which the fluid flows; and

a second pressure detection device for compensation of a zero point drift configured to detect the pressure of fluid at a position different from a position of the first pressure detection device,

wherein the zero point drift of a pressure of the first pressure detection device is compensated by substituting a value of a minimum pressure value obtained from an output of the first pressure detection device with a minimum pressure value obtained from a pulse wave propagation time and a pressure change amount, the pulse wave propagation time representing the time difference propagating between different two portions in the pipe line recorded between the first and second pressure detection devices, the pressure change amount being obtained from the output of the first pressure detection device.

2. A mass flowmeter, comprising:

a first strain gauge disposed in a bent section in a pipe line in which a centrifugal force or a centripetal force of fluid is acted, the fluid flows in the pipe line, and configured to detect the centrifugal force or the centripetal force of fluid; and

a second strain gauge which is disposed in the straight section in the pipe line different from the bent section;

a third strain gauge for a static pressure compensation disposed in a straight section in the pipe line different from the second strain gauge,

wherein a zero-point drift of a flow rate is compensated by substituting a value of a minimum pressure value obtained from an output of the first strain gauge with a minimum pressure value obtained from a pulse wave propagation time, a second pulse wave propagation time and a pressure change amount, the pulse wave propagation time represents the time difference propagating between different two portions in the pipe line recorded between the first and second strain gauges, the second pulse wave propagation time represents the time difference propagating between the two portions in the pipe line recorded between the second and third strain gauges, and the pressure change amount being obtained from each output of the first and third strain gauges.

3. The mass flowmeter according to claim 2, wherein a tube of elastic material is formed in the different two points in the pipe line between the first and second strain gauges.

4. The mass flowmeter according to claim 2, wherein a signal, after the zero point drift compensation using the pulse wave propagation time, is output as a pressure signal.

5. The mass flowmeter according to claim 4, wherein the pipe line resistance is measured from the pressure signal and the flow rate measured using the bent section.

6. A mass flowmeter, comprising:

a first strain gauge disposed in a bent section in a pipe line in which a centrifugal force or a centripetal force of fluid is acted, the fluid flows in the pipe line, and configured to detect the centrifugal force or the centripetal force of fluid; and

a check valve provided in the straight section in the pipe line the check valve configured to open when a fixed pressure is applied to the pipe line,

a third strain gauge for a static pressure compensation disposed in a straight section in the pipe line different from the second strain gauge, and

wherein

a third pulse wave propagation time is calculated based on a time of a fixed pressure change amount in the first strain gauge and an opening time of the check valve, the third pulse wave propagation time represents the time difference propagating between different two portions in the pipe line recorded between the first strain gauge and the check valve,

a fourth pulse wave propagation time is calculated based on a time of a fixed pressure change amount in the third strain gauge and an opening time of the check valve, the third pulse wave propagation time represents the time difference propagating between the two portions in the pipe line recorded between the third strain gauge and the check valve, and

a zero-point drift of a flow rate is compensated by substituting a minimum pressure value obtained from an output of the first pressure detection device with a minimum pressure value obtained from the third pulse wave propagation time, the fourth pulse wave propagation time and a pressure change amount, the pressure change amount being obtained based on each of the outputs of the first and third strain gauges.