US4513615A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal air flow meter
Assignee: Hitachi Ltd
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Filing: 1983-12-05
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Granted: 1985-04-30
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Expires: 2003-12-05
Abstract
Abstract A thermal air flow meter consists essentially of a hollow cylindrical support made of an insulating material, a heat-sensitive resistor formed on top of the support, and lead wires inserted into the hollow part of the support from either end and bonded thereto by glass. This flow meter measures the flow rate from changes in the resistance of the heat-sensitive resistor with temperature. The ratio of the inner diameter d 2 of the support to the outer diameter d 3 of the lead wires (d 2 /d 3 ) is at least 1.7. This arrangement can provide a thermal air flow meter with a quick response to changes in flow rate.
Inventors
- 👤 Kanemasa Sato
- 👤 Sadayasu Ueno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:15
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/68; G01F1/684; G01F1/6842; G01F1/688; G01F1/69; F; F02; F02B; F02B75/00; F02B75/02; F02B2075/022; F02B2075/027
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
103 words
In a thermal air flow meter which consists essentially of a hollow cylindrical support made of an insulating material, a heat-sensitive resistor formed on top of said support, and lead wires inserted into the hollow part of said support from either end of said support and bonded to said support by a heat-insulating adhesive, and which measures the flow rate on the basis of changes in resistance due to the temperature of said heat-sensitive resistor, the improvement wherein the ratio of the inner diameter d 2 of said support to the outer diameter d 3 of said lead wires is at least 1.7.
Claim 2
Dependent Claim
103 words
In a thermal air flow meter which consists essentially of a hollow cylindrical support made of an insulating material, a heat-sensitive resistor formed on top of said support, and lead wires inserted into the hollow part of said support from either end of said support and bonded to said support by a heat-insulating adhesive, and which measures the flow rate on the basis of changes in resistance due to the temperature of said heat-sensitive resistor, the improvement wherein the ratio of the inner diameter d 2 of said support to the outer diameter d 3 of said lead wires is at least 1.7.
Claim 3
Dependent Claim
22 words
The thermal air flow meter as defined in claim 1 wherein the ratio d 2 /d 3 is between 1.8 to 2.0.
Claim 4
Dependent Claim
16 words
The thermal air flow meter as defined in claim 1 wherein said adhesive is borosilicate glass.
Claim 5
Dependent Claim
25 words
The thermal air flow meter as defined in claim 1 wherein said adhesive is lead glass with a softening point of at least 800° C.
Claim 6
Dependent Claim
44 words
The thermal air flow meter as defined in claim 1 wherein the length l 2 of each of said lead wires from the end of said support to the attachment position thereof is at least 1.5 times the length l 1 of said support.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-29 | 1988-10-29 | 1989-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-29 | 1992-10-29 | 1993-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-29 | 1996-10-29 | 1997-04-30 | $7700.00 | Window Closed / Lapsed |