Measuring and testing – Simulating operating condition – Marine
Patent
1993-06-10
1994-05-24
Myracle, Jerry W.
Measuring and testing
Simulating operating condition
Marine
73862333, G01M 1500
Patent
active
053138260
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to internal combustion engine misfire and roughness detection and more particularly to a method and apparatus for detecting engine misfire, knock or roughness using signals generated relating to the torque of an operating internal combustion engine.
BACKGROUND OF THE INVENTION
Two primary objectives of automobile engine control systems are to maximize engine performance, such as power for passing, etc., and to minimize fuel consumption. Rough running engines affect both power output and fuel economy adversely. Onboard monitoring and control systems should be able to detect and, in some instances, correct for such roughness. Roughness may be due to incomplete burning of fuel in one or more cylinders. Extreme engine roughness occurs during cylinder misfire, that is, when no fuel is burned in one or more cylinders. Misfire can occur for several reasons, including lack of spark from the ignition system, malfunctioning of the fuel injection system, lack of sufficient air intake, faulty valves, etc.
While detection of roughness and misfiring during vehicle operation is highly desirable from the standpoints of performance and fuel economy, it has significant environmental impact as well. Incomplete burning of fossil fuels is a prime source of air pollution. An engine which misfires only 2% of the time, for example, may produce pollutant levels which exceed emission standards by 150%.
Governmental regulations covering emissions caused by cylinder misfire are being proposed. For example, the state of California has already notified automakers that beginning with the 1994 model year, vehicles sold in California must have onboard means for detecting and warning of cylinder misfire. Such means must be capable of identifying which particular cylinder is misfiring, or in the case of multiple cylinder misfire, indicating that more than one cylinder is misfiring. California regulators have also stated they would prefer a system which could additionally: determine precisely which cylinders are misfiring in the case of multiple misfires; identify sporadic, non-periodic misfiring events; detect isolated misfires occurring a small percentage of the time, for example, 5 or fewer misfires for every 1,000 firings; and function properly under all engine speeds and driving conditions. Other states, as well as the U.S. Environmental Protection Agency, have indicated that they may issue cylinder misfire regulations similar to those proposed for California.
Prior art devices for roughness and misfire detection in internal combustion engines have utilized several different approaches. For example, the measurement of rotational speed (RPM) fluctuations is disclosed in U.S. Pat. No. 4,843,870 to Citron et al., and U.S. Pat. No. 4,932,379 to Tang et al.; and SAE papers #900232 by Plapp et al., #890486 by Citron et al., and #890884 by Rizzoni.
Detecting roughness and misfire has also been attempted by determining the absence of a spark in the ignition system as disclosed in U.S. Pat. No. 4,886,029 to Lill et al. and U.S. Pat. No. 4,928,228 to Fujimoto. The spark plug has also been used as a plasma probe as described in Johnson and Rado, "Monitoring Combustion Quality in Internal Combustion Engines Using Spark Plug as s Plasma Probe," IEEE Transactions on Vehicular Technology Vol VT-24, No 2, May 1975.
Sensing temperature at the exhaust port of each cylinder is disclosed in U.S. Pat. No. 3,939,711 to Hanaoka. Using non-magnetostrictive torque sensing and speed measurements is disclosed in SAE paper #890485 by Mauer et al. A generic torque sensor and comparing mean or maximum versus minimum torque signals (and typically other signals such as RPM, accelerator depression level, etc.) to expected values stored in computer memory, is disclosed in U.S. Pat. No. 4,606,005 to Ribbens, and U.S. Pat. No. 4,940,030 to Morikawa. Monitoring exhaust chemistry, such as with a Lambda oxygen sensor in the exhaust flow, is taught in SAE paper #900232 by Plapp et al.
Each of these prior art approaches has dis
REFERENCES:
patent: 4589290 (1986-05-01), Sugiyama et al.
patent: 4803885 (1989-02-01), Nonomura et al.
Klauber Robert D.
Mandarino Joseph V.
Sprague Frederick P.
Vigmostad Erik B.
Myracle Jerry W.
Sensortech L.P.
Wingate C. Douglas
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