Flow rate measuring apparatus

• US 6,748,812 B1
• Filed: 11/09/2001
• Issued: 06/15/2004
• Est. Priority Date: 05/11/1999
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Takemura, Koichi, Nagaoka, Yukio
• Primary Examiner(s): PATEL, HARSHAD R
• Application Number:
  US10/019,989
• Time in Patent Office: 949 Days
• Field of Search: 738/612.9, 738/611.8, 738/611.9, 738/612.3, 738/612.7, 738/612.8, 702/1, 702/33, 702/39, 702/45, 702/48, 702/50, 702/54
• US Class Current: 73/861.29
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• CPC Class Codes: G01F 1/696 Circuits therefor, e.g. constant-current flow meters
• CPC Class Codes: G01F 25/10 of flowmeters

Abstract

A flow rate measuring apparatus includes: flow rate detection section 2 and 3 provided in a fluid flow path 1; a measuring section 10 for measuring an output from the flow rate detection sections 2 and 3; a cycle setting section 9 for setting a measurement cycle of the flow rate detection sections 2 and 3; a resolution setting section 7 for setting a measurement resolution of the measuring section 10; a flow rate calculation section 11 for calculating a flow rate based on an output from the measuring section 10; and a measurement control section 12 for controlling each of the sections.

Claims

1. A flow rate measuring apparatus, comprising:

a flow rate detection section provided in a fluid flow path;

a measuring section for measuring an output from the flow rate detection section;

a cycle setting section for setting a measurement cycle of the flow rate detection section;

a resolution setting section for setting a measurement resolution of the measuring section;

a flow rate calculation section for calculating a flow rate based on an output from the measuring section; and

a measurement control section for controlling each of the sections,

wherein

the measurement control section includes;

a regular measuring section for setting a predetermined value in the cycle setting section and the resolution setting section so as to obtain a measured flow rate based on a value obtained by the setting; and

a search measuring section for setting in the cycle setting section a cycle which is shorter than that set by the regular measuring section and for setting a coarse resolution in the resolution setting section so as to estimate a flow rate based on a value obtained by the setting.

2. A flow rate measuring apparatus according to claim 1, wherein:

the flow rate detection section includes a first transducer for transmitting an ultrasonic wave signal and a second transducer for receiving the ultrasonic wave signal;

the measuring section repeats an ultrasonic wave propagation between the first transducer and the second transducer so as to measure an accumulated time of the ultrasonic wave propagation;

the cycle setting section sets a measurement start cycle for the first transducer and the second transducer; and

the resolution setting section sets the number of times to repeat the ultrasonic wave propagation.

3. A flow rate measuring apparatus according to claim 1, wherein:

the flow rate detection section includes a thermal flow sensor;

the measuring section measures heat output from the flow sensor;

the cycle setting section sets a measurement cycle of the flow sensor; and

the resolution setting section sets the quantity of heat input to the flow sensor so as to set a measurement resolution of the measuring section.

4. A flow rate measuring apparatus according to claim 1, wherein the regular measuring section sets the measurement cycle in the cycle setting section so as to last for a long period of time as the measured flow rate is decreased.

5. A flow rate measuring apparatus according to claim 1, wherein the regular measuring section sets the measurement cycle in the cycle setting section so as to last for a long period of time as the estimated flow rate is decreased.

6. A flow rate measuring apparatus according to claim 1, wherein the regular measuring section sets the measurement resolution in the resolution setting section to be coarse as the estimated flow rate is increased.

7. A flow rate measuring apparatus according to claim 1, wherein when a difference between the measured flow rate and the estimated flow rate is less than a predetermined value, the regular measuring section sets the measurement cycle in the cycle setting section so as to last for a long period of time.

8. A flow rate measuring apparatus according to claim 1, wherein when a difference between the measured flow rate and the estimated flow rate is less than a predetermined value, the regular measuring section sets the measurement resolution in the resolution setting section to be coarse.

9. A flow rate measuring apparatus according to claim 1, wherein when a difference between the measured flow rate and the estimated flow rate is equal to or more than a predetermined value, the regular measuring section sets the measurement resolution in the resolution setting section to be fine.

10. A flow rate measuring apparatus according to claim 1, wherein when a difference between the measured flow rate and the estimated flow rate is equal to or more than a predetermined value, the regular measuring section sets the measurement cycle in the cycle setting section to be short.

11. A flow rate measuring apparatus according to claim 10, further comprising an integrating section for performing integrating processing using only the measured flow rate.

12. A flow rate measuring apparatus according to claim 10, further comprising an integrating section for performing integrating processing using the measured flow rate and an estimated flow rate, wherein a difference between the measured flow rate and the estimated flow rate is equal to or more than a predetermined value.

13. A flow rate measuring apparatus, comprising:

a flow rate detection section provided in a fluid flow path;

a measuring section for measuring an output from the flow rate detection section;

a cycle setting section for setting a measurement cycle of the flow rate detection section;

a resolution setting section for setting a measurement resolution of the measuring section;

a flow rate calculation section for calculating a flow rate based on an output from the measuring section; and

a measurement control section for controlling each of the sections,

wherein

the measurement control section includes;

a regular measuring section for setting a predetermined value in the resolution setting section so as to obtain a measured flow rate based on a value obtained by the setting; and

a search measuring section for setting a resolution, which is coarser than that set in the regular measuring section, in the resolution setting section so as to estimate a flow rate based on a value obtained by the setting.

14. A flow rate measuring apparatus, comprising:

a flow rate detection section provided in a fluid flow path;

a measuring section for measuring an output from the flow rate detection section;

a cycle setting section for setting a measurement cycle of the flow rate detection section;

a resolution setting section for setting a measurement resolution of the measuring section;

a flow rate calculation section for calculating a flow rate based on an output from the measuring section; and

a measurement control section for controlling each of the sections,

wherein

the measurement control section includes;

a search measuring section for setting a coarse resolution in the resolution setting section so as to estimate a flow rate based on a value obtained by the setting; and

a regular measuring section for setting a resolution, which is finer than that set in the search measuring section, in the resolution setting section so as to measure a highly-precise flow rate based on a value obtained by the setting.