Marine propulsion – Means for accomodating or moving engine fluids – Means for handling exhaust gas
Reexamination Certificate
2000-04-26
2001-11-13
Basinger, Sherman (Department: 3617)
Marine propulsion
Means for accomodating or moving engine fluids
Means for handling exhaust gas
C440S001000
Reexamination Certificate
active
06315624
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to marine engines and, more specifically, to detecting engine exhaust gas pressure in a fuel injected or direct fuel injected engine.
Marine engines typically include a power head, an exhaust housing, and a lower unit. A drive shaft extends from the power head, through the exhaust housing, and into the lower unit. The lower unit includes a gear case, which supports a propeller shaft. One end of the propeller shaft is engaged to the drive shaft, and a propeller is engaged to an opposing end of the shaft.
In order to maintain optimum combustion, as airflow to the cylinders increases, fuel flow to the cylinders also should increase. As airflow to the cylinders decreases, fuel flow to the cylinders also should decrease.
Many variables impact airflow to the cylinders including conditions at the propeller. For example, the depth at which an engine propeller is located in the water impacts air flow through the engine, including an amount of fresh air supplied to the engine cylinders. Fuel flow to the cylinders also is adjusted based on operating parameters such as atmospheric pressure and intake air temperature. An absolute pressure sensor typically is utilized for generating a signal representative of atmospheric pressure, and a temperature sensor typically is located at the engine air intake to generate a signal representative of intake air temperature. The sensors are coupled to, or part of, an electronic control unit (ECU), which samples the signals generated by the sensors and adjusts fuel flow according to the sampled signals.
An additional parameter that has a significant impact on fresh airflow to the engine cylinders is exhaust flow. Specifically, a key parameter governing the exhaust gas flow is the gas pressure within the exhaust system. Known commercial marine engines, however, do not utilize exhaust gas pressure data in controlling the fuel/air ratio in the engine cylinders.
More specifically, and until now, the difficulties and costs associated with measuring such exhaust gas pressure for controlling the fuel/air ratio during engine operations were prohibitive in commercial marine engines. For example, the carbon and soot resulting from the combustion process can collect and block the sensor, preventing it from reading pressure. In addition, exhaust gas from an internal combustion engine contains known corrosive compounds which can damage electrical components.
BRIEF SUMMARY OF THE INVENTION
The present invention, in one aspect, includes a probe for sensing exhaust gas pressure in an exhaust path of a marine engine during engine operation. More specifically, a marine engine typically has a power head including an internal combustion engine having an exhaust system with an exhaust outlet. The power head also includes an adapter. A main exhaust gas duct extends through the adapter, the exhaust housing, and into the lower unit. A key parameter in determining the amount of airflow through the engine is the gas pressure within the exhaust housing.
In an exemplary embodiment, the probe includes an elongate probe body and an engine engagement assembly secured to the probe body and configured to engage to the engine so that said probe body at least partially extends into the engine exhaust path. The probe body comprises a hollow, cylindrical shaped member, and at least one opening extends through a side wall of the cylindrical shaped member. In one specific embodiment, three openings extend through the cylindrical shaped member side wall, and the openings are radially spaced about 120° apart from each adjacent opening.
A cap is secured to and closes an open end of the probe cylindrical shaped member, and a pellet is located, i.e., trapped, within the cylindrical shaped member. Specifically, the cylindrical shaped member has an inner diameter surface and a ledge formed in the inner diameter surface. The pellet is trapped between the ledge and the cap. In one specific embodiment, the pellet is sintered metal.
The engine engagement assembly includes a threaded portion sized to be threadedly engaged within an opening in flow communication with the engine exhaust path, and a tube connection portion sized to be inserted within a tube. The tube is in flow communication with, for example, an engine ECU.
The probe typically is installed through an opening in a power head adapter and into flow communication with an exhaust duct that extends from the power head, through the exhaust housing, and through the engine lower unit. The probe is threadedly engaged to the power head, and a tube is coupled to and extends from the probe and is in flow communication with the engine ECU. A diaphragm may, for example, be in the flow path between the probe and the engine ECU to protect the ECU from chemicals and soot flowing through the engine exhaust duct.
During engine operation, exhaust output from each cylinder flows through the exhaust duct and past the probe. The flow of exhaust gas is partially determined by the pressure in the exhaust system. The exhaust gas pressure is communicated from the probe to the engine ECU. Using such pressure data as well as other operating data supplied to the engine ECU, the ECU controls the fuel/air ratio in the engine cylinders.
The sintered metal pellet located within the probe body dampens the exhaust pressure spikes as well as facilitates preventing soot and carbon from building up within the probe and possibly damaging or blocking the flow path through the probe. Specifically, the pellet holds the soot and carbon that enters into the probe at or around the tip of the probe. The tip of the probe is located in the hot exhaust flow, and as a result, the soot and carbon the collects within the probe burns and does not damage the probe nor block flow through the probe.
REFERENCES:
patent: 4466880 (1984-08-01), Torii et al.
patent: 5637792 (1997-06-01), Kimura et al.
patent: 5711148 (1998-01-01), Katoh
patent: 5911610 (1999-06-01), Fujimoto
Binversie Gregory J.
Leadingham Brian T.
Macier James E.
Raetzman Roger W.
Tetzlaff Patrick C.
Armstrong Teasdale LLP
Basinger Sherman
Bombardier Motor Corporation of America
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