Abstract: A fuel injection control system makes it possible to obtain an output of a lean combustion type engine through an easy operation, even in a throttle opening region of greater than a lean limit. A throttle valve is configured to be turnable up to an over-fully opened position, which is greater than a fully opened position that corresponds to a maximum air flow rate, where the air flow rate is not substantially varied from the maximum air flow rate. In a region where the throttle valve is operated to or above the fully opened position when under a high load, the fuel-air mixture is enriched and a high output is obtained by controlling the throttle opening through operating only a power lever.

Abstract: An engine control method and compensation suitable for the case that both of two manifold pressure sensors in individual groups have failed. When detection outputs from two manifold pressure sensors are different from each other, a first comparing section determines that one of the two sensors is abnormal. A manifold pressure estimating section calculates an estimated manifold pressure value according to an engine speed, throttle opening, and atmospheric pressure. A calculating section calculates a difference ?PMb between the detection output PMb and the estimated value PMcal. A calculating section calculates a difference ?PMa between the detection output PMa and the estimated value PMcal. A second comparing section identifies an abnormal one of these two manifold pressure sensors corresponding to a larger one of these differences ?PMa and ?PMb. When the remaining manifold pressure sensor has also failed, the estimated value PMcal is used as a substitutional value, then continuing the engine control.

Abstract: A failed manifold pressure sensor is identified in a control apparatus having two manifold pressure detecting systems as a failsafe. A first comparing unit outputs an abnormal signal when a difference ?P between manifold pressures PMa and PMb detected respectively by two sensors is larger than a threshold value DP. A manifold pressure estimating unit estimates the manifold pressure from the engine revolution Ne, a throttle opening PLP, and an atmospheric pressure PAa. The difference calculating unit calculates a difference ?PMb between the detected manifold pressure PMb and the estimated manifold pressure PMcal. The difference calculating unit calculates a difference ?PMa between the detected manifold pressure PMa and the estimated manifold pressure PMcal. A second comparing unit compares the difference ?PMa and the difference ?PMb in response to the aforementioned abnormal signal. The failed manifold pressure sensor is specified according to which one of the difference ?PMa and the difference ?PMb is larger.

Abstract: To identify a failed manifold pressure sensor in a control apparatus having two manifold pressure detection systems as a. A calculating unit calculates a difference between the manifold pressure detected by two sensors. A first comparing unit outputs an abnormal signal when the difference is larger than a threshold value. A calculating unit calculates a difference between the manifold pressure and the atmospheric pressure. A difference calculating unit calculates a difference between the manifold pressure and the atmospheric pressure. When the abnormal signal is outputted from the first comparing unit while an engine is stopped, a second comparing unit compares the differences in response thereto. Depending on which one of the differences is larger, it is determined which one of the manifold pressure sensors is abnormal.

Abstract: To identify a failed atmospheric pressure sensor in a control apparatus having two atmospheric pressure detecting systems as a failsafe. A first comparing unit outputs an abnormal signal when a difference between atmospheric pressures detected by two sensors is larger than a threshold value. An atmospheric pressure estimating unit estimates the atmospheric pressure from an engine revolution, a throttle opening, and a manifold pressure. The difference calculating unit calculates a difference between the detected atmospheric pressure and the estimated atmospheric pressure. The difference calculating unit calculates a difference between the detected atmospheric pressure and the estimated atmospheric pressure. When an abnormal signal is outputted from the first comparing unit, a second comparing unit compares the differences in response thereto. The failed atmospheric pressure sensor is identified according to which one of the differences is larger.

Abstract: A failure diagnosis apparatus and method permit specification of a failed atmospheric pressure sensor in an engine control apparatus having redundant pressure detection systems to ensure failsafe control of the engine. The apparatus includes a calculating unit that calculates a difference between a first atmospheric pressure and a second atmospheric pressure detected in respective pressure detection systems. A first comparing unit outputs an alarm when the difference is larger than a threshold value. A difference calculating unit calculates a first difference between the first atmospheric pressure and a manifold pressure. A difference calculating unit calculates a second difference between the second atmospheric pressure and the manifold pressure. A second comparing unit compares the first and second differences in response to output of the alarm from the first comparing unit while an engine is stopped. The sensor having abnormal function corresponds to the one for which the difference is larger.

Abstract: A fuel injection control system makes it possible to obtain an output of a lean combustion type engine through an easy operation, even in a throttle opening region of greater than a lean limit. A throttle valve is configured to be turnable up to an over-fully opened position, which is greater than a fully opened position that corresponds to a maximum air flow rate, where the air flow rate is not substantially varied from the maximum air flow rate. In a region where the throttle valve is operated to or above the fully opened position when under a high load, the fuel-air mixture is enriched and a high output is obtained by controlling the throttle opening through operating only a power lever.

Abstract: An engine control method and compensation suitable for the case that both of two manifold pressure sensors in individual groups have failed. When detection outputs from two manifold pressure sensors are different from each other, a first comparing section determines that one of the two sensors is abnormal. A manifold pressure estimating section calculates an estimated manifold pressure value according to an engine speed, throttle opening, and atmospheric pressure. A calculating section calculates a difference ?PMb between the detection output PMb and the estimated value PMcal. A calculating section calculates a difference ?PMa between the detection output PMa and the estimated value PMcal. A second comparing section identifies an abnormal one of these two manifold pressure sensors corresponding to a larger one of these differences ?PMa and ?PMb. When the remaining manifold pressure sensor has also failed, the estimated value PMcal is used as a substitutional value, then continuing the engine control.

Abstract: To provide a value to be replaced for an output of a manifold pressure sensor in case of failure of the manifold pressure sensor for detecting a manifold pressure for calculating the amount of fuel injection. An abnormality determination unit outputs an abnormal signal when an output voltage of a manifold pressure sensor is not within a predetermined range. A manifold pressure estimating unit calculates an estimated manifold pressure value on the basis of the engine revolution, a throttle opening, and an atmospheric pressure. The manifold pressure estimating unit uses the estimated value as a substitute value of the output of the manifold pressure sensor and continues to control the engine when the manifold pressure sensor has failed.

Abstract: To provide a value to be replaced for an output of a manifold pressure sensor in case of failure of the manifold pressure sensor for detecting a manifold pressure for calculating the amount of fuel injection. An abnormality determination unit outputs an abnormal signal when an output voltage of a manifold pressure sensor is not within a predetermined range. A manifold pressure estimating unit calculates an estimated manifold pressure value on the basis of the engine revolution, a throttle opening, and an atmospheric pressure. The manifold pressure estimating unit uses the estimated value as a substitute value of the output of the manifold pressure sensor and continues to control the engine when the manifold pressure sensor has failed.

Abstract: A failure diagnosis apparatus and method permit specification of a failed atmospheric pressure sensor in an engine control apparatus having redundant pressure detection systems to ensure failsafe control of the engine. The apparatus includes a calculating unit that calculates a difference between a first atmospheric pressure and a second atmospheric pressure detected in respective pressure detection systems. A first comparing unit outputs an alarm when the difference is larger than a threshold value. A difference calculating unit calculates a first difference between the first atmospheric pressure and a manifold pressure. A difference calculating unit calculates a second difference between the second atmospheric pressure and the manifold pressure. A second comparing unit compares the first and second differences in response to output of the alarm from the first comparing unit while an engine is stopped. The sensor having abnormal function corresponds to the one for which the difference is larger.

Abstract: A failed manifold pressure sensor is identified in a control apparatus having two manifold pressure detecting systems as a failsafe. A first comparing unit outputs an abnormal signal when a difference ?P between manifold pressures PMa and PMb detected respectively by two sensors is larger than a threshold value DP. A manifold pressure estimating unit estimates the manifold pressure from the engine revolution Ne, a throttle opening PLP, and an atmospheric pressure PAa. The difference calculating unit calculates a difference ?PMb between the detected manifold pressure PMb and the estimated manifold pressure PMcal. The difference calculating unit calculates a difference ?PMa between the detected manifold pressure PMa and the estimated manifold pressure PMcal. A second comparing unit compares the difference ?PMa and the difference ?PMb in response to the aforementioned abnormal signal. The failed manifold pressure sensor is specified according to which one of the difference ?PMa and the difference ?PMb is larger.

Abstract: To identify a failed atmospheric pressure sensor in a control apparatus having two atmospheric pressure detecting systems as a failsafe. A first comparing unit outputs an abnormal signal when a difference between atmospheric pressures detected by two sensors is larger than a threshold value. An atmospheric pressure estimating unit estimates the atmospheric pressure from an engine revolution, a throttle opening, and a manifold pressure. The difference calculating unit calculates a difference between the detected atmospheric pressure and the estimated atmospheric pressure. The difference calculating unit calculates a difference between the detected atmospheric pressure and the estimated atmospheric pressure. When an abnormal signal is outputted from the first comparing unit, a second comparing unit compares the differences in response thereto. The failed atmospheric pressure sensor is identified according to which one of the differences is larger.

Abstract: To identify a failed manifold pressure sensor in a control apparatus having two manifold pressure detection systems as a. A calculating unit calculates a difference between the manifold pressure detected by two sensors. A first comparing unit outputs an abnormal signal when the difference is larger than a threshold value. A calculating unit calculates a difference between the manifold pressure and the atmospheric pressure. A difference calculating unit calculates a difference between the manifold pressure and the atmospheric pressure. When the abnormal signal is outputted from the first comparing unit while an engine is stopped, a second comparing unit compares the differences in response thereto. Depending on which one of the differences is larger, it is determined which one of the manifold pressure sensors is abnormal.

Abstract: To reduce the number of parts, improve the mountability and maintainability, and allow for a reduction in the size and weight an engine is provided having a crankshaft, a crankcase having a plurality of bearing portions for rotatably supporting the crankshaft with each of the bearing portions being dividable along a divisional plane arranged on the axis of the crankshaft. Cylinder barrels are connected to the crankcase and include cylinder bores with cylinder heads connected to the cylinder barrels. The cylinder heads are integrated with portions of the cylinder barrels forming at least the cylinder bores to form cylinder blocks. The cylinder blocks and the crankcase are fastened together by a plurality of fastening bolts having axes parallel to the axes of the cylinder bores and extending through at least the cylinder blocks, with a compressive structure in the axial direction of the fastening bolts.

Abstract: To simplify the connection of a cylinder barrel and a cylinder head to, a crankcase and to reduce the weight of an engine. A liquid-cooled engine is provided with the crankcase wherein a cylinder barrel having a water jacket on the cylinder side for cooling is connected to the crankcase. A cylinder head is connected to the cylinder barrel. A plurality of mounting bosses extend from fitting planes to a crankcase of the cylinder barrels and to cylinder heads that are integrated with cylinder blocks. The cylinder barrels and the cylinder heads are integrated in a state in which the mounting bosses encircle the cylinder bores and the cylinder blocks are fastened to the crankcase by bolts inserted into each mounting boss.

Abstract: To reduce the number of parts, improve the mountability and maintainability, and allow for a reduction in the size and weight an engine is provided having a crankshaft, a crankcase having a plurality of bearing portions for rotatably supporting the crankshaft with each of the bearing portions being dividable along a divisional plane arranged on the axis of the crankshaft. Cylinder barrels are connected to the crankcase and include cylinder bores with cylinder heads connected to the cylinder barrels. The cylinder heads are integrated with portions of the cylinder barrels forming at least the cylinder bores to form cylinder blocks. The cylinder blocks and the crankcase are fastened together by a plurality of fastening bolts having axes parallel to the axes of the cylinder bores and extending through at least the cylinder blocks, with a compressive structure in the axial direction of the fastening bolts.

Abstract: To simplify the connection of a cylinder barrel and a cylinder head to, a crankcase and to reduce the weight of an engine. A liquid-cooled engine is provided with the crankcase wherein a cylinder barrel having a water jacket on the cylinder side for cooling is connected to the crankcase. A cylinder head is connected to the cylinder barrel. A plurality of mounting bosses extend from fitting planes to a crankcase of the cylinder barrels and to cylinder heads that are integrated with cylinder blocks. The cylinder barrels and the cylinder heads are integrated in a state in which the mounting bosses encircle the cylinder bores and the cylinder blocks are fastened to the crankcase by bolts inserted into each mounting boss.

Abstract: A control system that enables optimum lean burn control only by operating one lever beyond a lean limit of a lean burn engine. A link mechanism opens a throttle valve at an angle according to the manipulated variable of a power lever while the throttle valve is located in a range from an idle position to a full throttle position. When the power lever is further operated beyond the full throttle position of the throttle valve, the throttle valve is kept at a full throttle state independent of the position of the power lever and only a positional sensor outputs a signal according to the manipulated variable of the power lever. The degree of leaning of an air-fuel mixture is determined according to the manipulated variable of the power lever.

Abstract: A control system that enables optimum lean bum control only by operating one lever beyond a lean limit of a lean bum engine. A link mechanism opens a throttle valve at an angle according to the manipulated variable of a power lever while the throttle valve is located in a range from an idle position to a full throttle position. When the power lever is further operated beyond the full throttle position of the throttle valve, the throttle valve is kept at a full throttle state independent of the position of the power lever and only a positional sensor outputs a signal according to the manipulated variable of the power lever. The degree of leaning of an air-fuel mixture is determined according to the manipulated variable of the power lever.