US5222471A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Emission control system for an internal combustion engine
Assignee: Kohler Co
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Filing: 1992-09-18
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Granted: 1993-06-29
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Expires: 2012-09-18
Abstract
Abstract A system for controlling the air/fuel ratio input to a small engine measures the oxygen level in the engine's exhaust and compares it with a reference level. A stepper motor controls the air/fuel ratio and it is advanced one step each time a clock pulse is produced in a direction determined by the level of exhaust oxygen. A fault detector circuit stops the engine if the sensed oxygen level is outside a preset range for more than a preset time interval.
Inventors
- 👤 Jeffrey S. Stueven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:55
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/22; F02D41/221; F02D35/00; F02D35/0007; F02D35/0015; F02D35/0046; F02D35/0053; F02D35/0092; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/40
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
202 words
A system for controlling the air/fuel mixture input to an internal combustion engine which comprises: a sensor mounted to the engine for sensing the level of an exhaust gas and producing an analog signal indicative of that level; means for producing a reference level signal indicative of the desired level of said exhaust gas; a comparator connected to receive the analog exhaust gas signal and the reference level signal and being operable to produce a first logic level output if the analog exhaust gas signal exceeds the reference level signal and produce a second logic level output if the analog exhaust gas signal is less than the reference level signal; a clock for producing clock pulses; a flip-flop connected to the comparator and the clock and being operable to store the state of the comparator output each time a clock pulse is received and to produce a corresponding direction signal at an output; a stepper motor mounted to the engine for controlling the air/fuel mixture; and a stepper motor control connected to the clock and the flip-flop and being operable to advance the stepper motor one step for each received clock pulse in the direction indicated by the state of the flip-flop.
Claim 2
Independent Claim
202 words
A system for controlling the air/fuel mixture input to an internal combustion engine which comprises: a sensor mounted to the engine for sensing the level of an exhaust gas and producing an analog signal indicative of that level; means for producing a reference level signal indicative of the desired level of said exhaust gas; a comparator connected to receive the analog exhaust gas signal and the reference level signal and being operable to produce a first logic level output if the analog exhaust gas signal exceeds the reference level signal and produce a second logic level output if the analog exhaust gas signal is less than the reference level signal; a clock for producing clock pulses; a flip-flop connected to the comparator and the clock and being operable to store the state of the comparator output each time a clock pulse is received and to produce a corresponding direction signal at an output; a stepper motor mounted to the engine for controlling the air/fuel mixture; and a stepper motor control connected to the clock and the flip-flop and being operable to advance the stepper motor one step for each received clock pulse in the direction indicated by the state of the flip-flop.
Claim 3
Dependent Claim
19 words
The system as recited in claim 1 which includes an averaging circuit connected between the sensor and the comparator.
Claim 4
Dependent Claim
14 words
The system as recited in claim 1 in which the measured gas is oxygen.
Claim 5
Dependent Claim
42 words
The system as recited in claim 1 which includes a fault detector connected to receive the analog exhaust gas signal and being operable to indicate a fault if that signal remains outside a preset range of values for a preset time interval.
Claim 6
Dependent Claim
84 words
The system as recited in claim 4 in which the fault detector includes: comparator means for receiving the analog exhaust gas signal and producing a logic level signal which indicates if the level thereof is inside or outside of said preset range; a counter connected to the clock and the comparator means and being operable to generate a fault indicate signal if the logic level signal indicates the analog exhaust gas signal is outside said preset range for longer than said preset time interval.
Claim 7
Dependent Claim
35 words
The system as recited in claim 5 in which the preset range is established by said reference level signal and a high oxygen level reference signal produced by said means for producing a reference signal.
Claim 8
Dependent Claim
28 words
The system as recited in claim 4 in which the fault detector includes means for stopping the engine for a shut down interval when a fault is indicated.
Claim 9
Dependent Claim
20 words
The system as recited in claim 7 in which the fault detector includes means for visually indicating a fault condition.
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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) | 1996-06-28 | 1996-12-28 | 1997-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-28 | 2000-12-28 | 2001-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-28 | 2004-12-28 | 2005-06-29 | $7700.00 | Window Closed / Lapsed |