US4344322A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for air flow rate measurement in the air intake tube of an internal combustion engine
Assignee: Robert Bosch GmbH
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Filing: 1980-06-06
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Granted: 1982-08-17
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Expires: 2000-06-06
Abstract
Abstract A device for air flow rate measurement in the air intake tube of an internal combustion engine which has at least two temperature-dependent resistors in different branches of a bridge circuit having closed-loop electric current control, and which is characterized in that the temperature-dependent resistors are embodied as hot wires, that a temperature above the aspirated air temperature is selected for both hot wires, and that the difference of the hot wire temperatures is held to a constant value. The purpose of the device is to provide air flow rate measurement which is as error-free as possible, even when the aspirated air temperature is fluctuating rapidly. An identically embodied suspension and fastening of the individual hot wires is given as an example for the spatial disposition of the individual hot wires in the air intake tube.
Inventors
- 👤 Gunther Plapp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:00
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/68; G01F1/696; G01F1/698
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
174 words
A device for measuring the air flow rate of the air flowing in the air intake tube of an internal combustion engine, comprising a bridge circuit having: at least two hot wire resistors located in different branches of the bridge circuit, and identically positioned but spatially separated in the air intake tube; and means for providing closed-loop electric current control and maintaining the temperature difference between the resistors constant, wherein; (i) The temperature of each hot wire is maintained above the temperature of the air flow; and (ii) The temperature coefficients of the branches containing the hot wires have the following relationship: ##EQU4## where αKO' is the temperature coefficient of one of said branches of the bridge circuit; αHO is the temperature coefficient of the other of said branches of the bridge circuit; Tu1 is the excess temperature of a hot wire in said one bridge branch over the air flow temperature; and Tu2 is the excess temperature of at least one hot wire in said other bridge branch over the air flow temperature.
Claim 2
Independent Claim
174 words
A device for measuring the air flow rate of the air flowing in the air intake tube of an internal combustion engine, comprising a bridge circuit having: at least two hot wire resistors located in different branches of the bridge circuit, and identically positioned but spatially separated in the air intake tube; and means for providing closed-loop electric current control and maintaining the temperature difference between the resistors constant, wherein; (i) The temperature of each hot wire is maintained above the temperature of the air flow; and (ii) The temperature coefficients of the branches containing the hot wires have the following relationship: ##EQU4## where αKO' is the temperature coefficient of one of said branches of the bridge circuit; αHO is the temperature coefficient of the other of said branches of the bridge circuit; Tu1 is the excess temperature of a hot wire in said one bridge branch over the air flow temperature; and Tu2 is the excess temperature of at least one hot wire in said other bridge branch over the air flow temperature.
Claim 3
Dependent Claim
22 words
A device as defined in claim 1, wherein said other bridge branch has at least two electric hot wires disposed in sequence.
Claim 4
Dependent Claim
17 words
A device as defined by claim 1, wherein the individual hot wires have the same geometric embodiment.
Claim 5
Dependent Claim
23 words
A device as defined by claim 1, wherein the hot wire having the highest temperature is located downstream in the air intake tube.
References Cited (Backward Citations)
US4080821A
Cited
US4279146A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-08-16 | 1986-02-15 | 1986-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-16 | 1990-02-15 | 1990-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-16 | 1994-02-15 | 1994-08-17 | $7700.00 | Window Closed / Lapsed |