US4599696A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for diagnosing an internal combustion engine
Assignee: Subaru Corp
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Filing: 1983-09-26
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Granted: 1986-07-08
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Expires: 2003-09-26
Abstract
Abstract A system for diagnosing an internal combustion engine having an air-flow meter. The air-flow meter comprises a voltage divider including a variable resistor. A wiper of the variable resistor is operatively connected to a flap in an intake passage so as to produce an output voltage, responsive to the volume of the intake air, a computor is provided for computing the volume of the intake air from the output voltage and a fixed voltage at one end of the variable resistor, a smoothing capacitor is provided for charging the fixed voltage and a diagnosing circuit is provided to respond to the fixed voltage for producing a diagnosis signal when the fixed voltage exceeds a predetermined range.
Inventors
- 👤 Toshio Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:44
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/18; F02D41/22; F02D41/222; G; G01; G01F; G01F25/00; G01F25/10; G05; G05B; G05B9/00; G05B9/02; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/40
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
204 words
A system for diagnosing an internal combustion engine comprising an air-flow meter including a variable resistor responsive to volume of intake air of the engine for producing an output voltage and having a movable contact, one end of the variable resistor being connected to a fixed voltage terminal normally having a fixed voltage, the other end of the variable resistor being connected to a ground terminal, and the movable contact of the variable resistor being connected to a variable voltage terminal, voltage between the movable terminal and the ground terminal being responsive to the volume of the intake air of the engine for producting said output voltage, a first smoothing capacitor connected between the variable voltage terminal and the ground terminal for charging thereon said output voltage of the air-flow meter, a second smoothing capacitor connected between said fixed voltage terminal and the ground terminal for charging thereon said fixed voltage, means comprising a diagnosing circuit for detecting a fault of the air-flow meter for producing a diagnosis signal when said fixed voltage varies beyond a predetermined range which is smaller than the range of fluctuation of the output voltage at the movable contact, so as to diagnose a fault of the air-flow meter.
Claim 2
Independent Claim
204 words
A system for diagnosing an internal combustion engine comprising an air-flow meter including a variable resistor responsive to volume of intake air of the engine for producing an output voltage and having a movable contact, one end of the variable resistor being connected to a fixed voltage terminal normally having a fixed voltage, the other end of the variable resistor being connected to a ground terminal, and the movable contact of the variable resistor being connected to a variable voltage terminal, voltage between the movable terminal and the ground terminal being responsive to the volume of the intake air of the engine for producting said output voltage, a first smoothing capacitor connected between the variable voltage terminal and the ground terminal for charging thereon said output voltage of the air-flow meter, a second smoothing capacitor connected between said fixed voltage terminal and the ground terminal for charging thereon said fixed voltage, means comprising a diagnosing circuit for detecting a fault of the air-flow meter for producing a diagnosis signal when said fixed voltage varies beyond a predetermined range which is smaller than the range of fluctuation of the output voltage at the movable contact, so as to diagnose a fault of the air-flow meter.
Claim 3
Dependent Claim
37 words
The system according to claim 1, further comprising computer means for computing the volume of the intake air from said output voltage and said fixed voltage at said fixed voltage terminal and connected to said diagnosing circuit.
Claim 4
Dependent Claim
40 words
The system according to claim 1, wherein said air-flow meter further comprises a voltage divider comprising another resistor and said variable resistor, and a flap provided in an intake passage of said engine and operatively connected to said movable contact.
Claim 5
Dependent Claim
42 words
The system according to claim 3, further comprising a constant voltage circuit, said another resistor is connected between said constant voltage circuit and said one end of said variable resistor, diodes respectively connected between each said capacitors and said constant voltage circuit.
Claim 6
Dependent Claim
34 words
The system according to claim 1, wherein said diagnosing circuit comprising, comparator means for detecting the fault of said air-flow meter by operatively comparing the level of said fixed voltage with a predetermined reference.
Claim 7
Dependent Claim
50 words
The system according to claim 5, wherein said comparator means comprises a window comparator comprising two comparators and an OR gate connected between outputs of said two comparators and said other input of said first AND gate and said other input of said third AND gate via said second inverter.
Claim 8
Dependent Claim
86 words
The system according to claim 5, wherein said diagnosing circuit further comprising, a counter- and logic circuit operatively connected to said comparator means comprising a first AND gate, a second AND gate and a first counter connected in series, an output of said counter being fed back via a first inverter to another input of said second AND gate, and an oscillator connected to an input of said first AND gate, the other input of said first AND gate is operatively connected to said comparator means.
Claim 9
Dependent Claim
79 words
The system according to claim 7, wherein said counter- and logic circuit further comprises a third AND gate and a second counter connected to an output of said third AND gate, said second counter having an output connected to reset inputs of said first and second counters, one input of said third AND gate is connected to said oscillator, and a second inverter is operatively connected between said comparator means and said other input of said third AND gate.
Claim 10
Dependent Claim
28 words
The system according to claim 8, wherein said counter- and logic circuit further comprises a delay circuit connected between said output and reset input of said second counter.
Claim 11
Dependent Claim
43 words
The system according to claim 1, further comprising a fail-safe circuit means for generating a respective fail-safe signal dependent on specific detected conditions of operation of the engine, and gate means responsive to said diagnosing signal for passing said respective fail-safe signal therethrough.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-07-07 | 1990-01-06 | 1990-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-07 | 1994-01-06 | 1994-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-07 | 1998-01-06 | 1998-07-08 | $7700.00 | Window Closed / Lapsed |