Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Reexamination Certificate
1999-02-17
2001-09-04
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
C073S115060
Reexamination Certificate
active
06283107
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to marine propulsion engines, and more specifically, to determining atmospheric pressure and exhaust back pressure.
Fuel flow to cylinders in engines including electronic fuel injection systems typically is adjusted based on a number of engine operating parameters, including air flow. For example, as air flow to the cylinders increases, fuel flow to the cylinders also must increase in order to maintain good combustion. As air flow to the cylinders decreases, fuel flow also must decrease.
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.
Another parameter that has a significant impact on air flow through the engine is exhaust back pressure. Specifically, outboard motors vent exhaust gases downwardly through an exhaust housing to a through-the-hub propeller. Hydrodynamic effects due, for example, to propeller rotation, impact the exhaust back pressure. Increased back pressure can restrict or prevent the venting of exhaust gases.
To determine exhaust back pressure, a pressure sensor can be added in the exhaust flow path. Adding a pressure sensor, however, increases the engine cost and complexity. Further, by adding another sensor, engine reliability may be adversely impacted since an extra sensor increases the possibility for a sensor failure.
It would be desirable to enable determination of both atmospheric pressure as well as engine exhaust back pressure, yet avoid the extra cost and complexity, and reliability concerns associated with adding an additional sensor to the engine.
BRIEF SUMMARY OF THE INVENTION
These and other objects may be attained by an engine including, in one embodiment, a pressure sensor utilized for determining both atmospheric, or barometric, pressure and engine exhaust back pressure. More specifically, and in the one embodiment, the engine includes an electronic control unit (ECU) including a processor. The pressure sensor is a component of the ECU, and the pressure sensor is in communication, e.g., via a conduit, with the engine exhaust duct.
The processor is programmed to obtain signals from the pressure sensor that are representative of both barometric pressure and engine exhaust back pressure. More particularly, the processor is programmed to sample a pressure representative signal generated by the sensor during a first time period to obtain a signal representative of barometric pressure, and to sample a pressure representative signal generated by the sensor during a second time period to obtain a signal representative of engine exhaust back pressure. The first time period initiates when the engine ignition switch is turned on, and terminates prior to when the engine generates exhaust. The second time period initiates upon termination of the first time period, and terminates when the engine ignition switch is turned off. Using the pressure sensor and processor described above, both atmospheric pressure as well as engine exhaust back pressure are determined, yet the extra cost and complexity associated with adding an extra sensor are avoided. In addition, by using only one sensor to determine both barometric and engine exhaust back pressure, reliability concerns associated with adding an additional sensor to the engine are avoided.
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Armstrong Teasdale LLP
Bombardier Motor Corporation of America
Castro Arnold
Dolinar Andrew M.
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