JP2015148193A - Fuel property determination device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a mixture ratio of different fuel and kinds of the different fuel with respect to reference fuel even if fuel is three or more kinds of mixture fuel, related to a fuel property determination device of an internal combustion engine.SOLUTION: A fuel property determination device of an internal combustion engine comprises a pressure sensor which detects crank case inner pressure, and an oil temperature sensor which detects an oil temperature in an oil pan. At the warmup of the engine, a mixture ratio of different fuel with respect to reference fuel and kinds of the different fuel are estimated on the basis of a relationship between the crank case inner pressure and the oil temperature at a use of the reference fuel during the warmup of the engine, the oil temperature and the crank case inner pressure when the crank case inner pressure indicates a maximum value during the warmup of the engine, a boiling point of the different fuel which is estimated to be added to the reference fuel, and a reference increase amount being an increase amount of the crank case inner pressure which is generated in the vicinity of the boiling point of the different fuel when the different fuel is added to the reference fuel at a prescribed mixture ratio.

Description

  The present invention relates to a fuel property determination device for an internal combustion engine.

  Conventionally, for example, Patent Document 1 discloses a fuel property determination apparatus for an internal combustion engine that estimates an alcohol concentration of a fuel using an alcohol concentration sensor.

JP 2011-001856 A JP-A-10-317936 JP 2006-525454 A JP-A-2005-346441 JP2012-021435A

  In the estimation method of the alcohol concentration of the fuel described in Patent Document 1 using the alcohol concentration sensor, when three or more kinds of mixed fuels including the reference fuel are used, the mixing of the different fuels with respect to the reference fuel is performed. The ratio and type of each different fuel cannot be estimated.

  The present invention has been made to solve the above-described problems, and even with three or more mixed fuels, the mixing ratio of each different fuel to the reference fuel and the type of each different fuel can be estimated. An object of the present invention is to provide a fuel property determination device for an internal combustion engine.

The present invention is a fuel property determination device for an internal combustion engine, comprising: a pressure sensor that detects a crankcase internal pressure; and an oil temperature sensor that detects an oil temperature in an oil pan.
The relationship between the crankcase internal pressure and the oil temperature when the reference fuel is used during the engine warm-up period, and the oil temperature and crankcase internal pressure when the crankcase internal pressure reaches the maximum during the engine warm-up period And the crankcase internal pressure that occurs near the boiling point of the dissimilar fuel when the dissimilar fuel is mixed at a predetermined mixing ratio with respect to the reference fuel. The mixing ratio of the different fuel to the reference fuel and the type of the different fuel are estimated based on the reference increase amount that is the increase amount of the fuel.

  According to the present invention, even if there are three or more types of mixed fuel, it is possible to estimate the mixing ratio of each different fuel to the reference fuel and the type of each different fuel.

It is a figure showing the relationship between the oil temperature in the oil pan at the time of engine warm-up, and crankcase internal pressure. It is a figure for demonstrating the determination method of the fuel property in Embodiment 1 of this invention. A graph showing the relationship between the oil temperature in the oil pan and the crankcase internal pressure during warm-up in an internal combustion engine having a function capable of maintaining the crankcase internal pressure at a negative pressure when using 100% reference fuel. is there.

Embodiment 1 FIG.
The fuel property determination apparatus according to Embodiment 1 of the present invention is applied to an internal combustion engine that can use a mixed fuel of a predetermined reference fuel and a different fuel. More specifically, as an example, the internal combustion engine of the present embodiment is designed such that gasoline is used as a reference fuel and ethanol is used as a different fuel in a normal state. In addition, in the internal combustion engine of the present embodiment, it is assumed that methanol as a different fuel other than ethanol is mixed.

  In the internal combustion engine (that is, an internal combustion engine that does not assume that methanol is mixed as a normal state), there is the following problem when methanol is contained in the fuel at a high concentration. That is, corrosion and wear are likely to occur in fuel-related parts such as fuel pipes. In addition, since the evaporability is different compared to when using regular fuel, there is a difference in startability and transient (acceleration) characteristics. As a result, various engine control changes are required. Therefore, when methanol is expected to be mixed, it is possible to estimate not only the mixing ratio of ethanol that is normally scheduled for use with respect to the reference fuel, but also the presence or absence of mixing of methanol and its mixing ratio. Is preferred.

  Therefore, in the fuel property determination device of the present embodiment, the mixing ratio of each different fuel (ethanol and methanol) with respect to the reference fuel (gasoline) and the type of each different fuel are estimated using the method described below. As sensors used for such estimation, the internal combustion engine is provided with a pressure sensor for detecting the crankcase internal pressure and an oil temperature sensor for detecting the temperature of the oil in the oil pan (oil temperature). Yes.

  FIG. 1 is a graph showing the relationship between the oil temperature in the oil pan and the crankcase internal pressure during engine warm-up. FIG. 1 shows a case where the internal combustion engine is started in a state where the oil temperature is lower than the boiling point of methanol, which is a different type of fuel to be mixed. The waveform indicated by a broken line in FIG. 1 is obtained when 100% reference fuel (gasoline) is used, and the waveform indicated by a solid line in FIG. 1 is a mixture of different types of fuel (methanol) with respect to the reference fuel. Of time.

  In the case of 100% gasoline fuel consisting of multiple components, evaporation gradually proceeds from the low boiling point components of the fuel contained in the oil in the oil pan as the oil temperature rises during warm-up. As a result, the crankcase internal pressure gradually increases. On the other hand, when methanol consisting of a single component (that is, having a specific boiling point) is mixed with this gasoline, the methanol evaporates rapidly when the oil temperature becomes a value near the boiling point of methanol. . As a result, the inside of the crankcase is basically a closed space, and as shown in FIG. 1, the crankcase internal pressure rises due to the evaporation of methanol and shows a maximum value. Therefore, when a difference (increase) in the crankcase internal pressure is recognized with respect to 100% gasoline fuel when the oil temperature is close to the boiling point of methanol, it can be determined that methanol is mixed. .

  FIG. 2 is a diagram for explaining a fuel property determination method according to Embodiment 1 of the present invention. In the present embodiment, focusing on the phenomenon in the crankcase during warm-up described above by taking methanol as an example, the mixing ratio of each different fuel (methanol and ethanol) to the reference fuel (gasoline) and each different fuel Estimate the type of

  Specifically, the fuel property determination device includes an ECU (Electronic Control Unit). In the ECU memory, the relationship A between the crankcase internal pressure and the oil temperature when using 100% of the reference fuel (gasoline) during the engine warm-up period, and the boiling points of methanol and ethanol, which are different types of fuel to be judged Is remembered. Further, in the ECU memory, when different fuel (methanol or ethanol) is mixed at a predetermined mixing ratio (here, 100% is used as an example) with respect to the reference fuel, it is generated near the boiling point of the different fuel. A reference increase amount that is an increase amount of the crankcase internal pressure is stored. The reference increase here means the maximum value when the crankcase internal pressure becomes maximum near the boiling point of the above-mentioned different fuel, and the fuel of 100% reference fuel at the same oil temperature as the oil temperature at the maximum value. This corresponds to the differential pressure from the crankcase internal pressure during use. This differential pressure is referred to as a reference differential pressure Paref when the different fuel is methanol, and is referred to as a reference differential pressure Pbref when ethanol is used. These reference differential pressures Paref and Pbref are used as reference values when estimating the mixing ratio of different fuels as follows. When the crankcase internal pressure is changed in accordance with the operation state (engine load and engine speed) during the warm-up period for estimating the fuel property, the relationship A and the reference differential pressures Paref and Pbref are predetermined. It is preferably stored for each operation state, and it is preferable to use one according to the operation state at the time of the following fuel property determination.

  The ECU uses the pressure sensor and the oil temperature sensor described above to obtain the oil temperature and the crankcase internal pressure when the crankcase internal pressure shows the maximum value during the warm-up period. The ECU determines that methanol is mixed in the fuel when the crankcase internal pressure is higher than a predetermined determination value when the oil temperature is a value near the boiling point of methanol. Similarly, when the crankcase internal pressure is higher than a predetermined determination value when the oil temperature is a value near the boiling point of ethanol, the ECU determines that ethanol is mixed in the fuel. Each judgment value used here is the value of the crankcase internal pressure when the oil temperature is the boiling point value of the different fuel in the relationship A in order to detect the increase level of the crankcase internal pressure accompanying the evaporation of the different fuel. Set as a reference.

  Further, when the crankcase internal pressure shows a maximum value when the oil temperature becomes a value near the boiling point of the different fuel during the warm-up period, the ECU determines that the maximum value is the same as the oil temperature at the maximum value. The differential pressure from the crankcase internal pressure when using 100% reference fuel at oil temperature is calculated. As shown in FIG. 2, the differential pressure Pa corresponds to the differential pressure when the heterogeneous fuel is methanol, and the differential pressure Pb corresponds to the differential pressure when it is ethanol. The ECU estimates the concentration (mixing ratio) of methanol with respect to the reference fuel by comparing the differential pressure Pa and the reference differential pressure Paref when detecting the mixing of methanol. More specifically, the differential pressure Pa increases as the concentration of methanol with respect to the reference fuel increases. When the differential pressure when the methanol concentration is 100% is used as the reference differential pressure Paref, the ECU calculates the ratio of the differential pressure Pa to the reference differential pressure Paref, and uses the calculated ratio of methanol relative to the reference fuel. Obtained as an estimate of the mixing ratio. The mixing ratio of ethanol can also be performed in the same manner as described above. This is the same when there is a different type of fuel that is expected to be mixed in addition to methanol and ethanol.

  As described above, the value of the oil temperature when the crankcase internal pressure shows the maximum value during warm-up corresponds to the boiling point of the different fuel, so the crankcase during the warm-up period when the oil temperature rises The type of the different fuel can be estimated based on the oil temperature corresponding to the maximum value of the internal pressure. Further, when different fuels are mixed with the reference fuel, the maximum value of the crankcase internal pressure increases as the mixing ratio of the different fuels increases. Therefore, the mixing ratio of different fuels can be estimated based on the maximum value. Thus, according to the fuel property determination apparatus of the present embodiment, the reference fuel (not only when there is one different fuel but also when there are a plurality of different fuels (for example, methanol and ethanol)) For example, it is possible to estimate the mixing ratio of each different fuel to gasoline) and the type of each different fuel. In addition, since it is possible to estimate the fuel property, it is possible to promptly notify the user that methanol is contained in the fuel when the mixing of methanol is detected. Further, the ECU can cope with switching to engine control corresponding to the methanol-mixed fuel. Thereby, deterioration of fuel system components can be prevented, and deterioration of operability such as startability can be prevented.

  FIG. 3 shows the relationship between the oil temperature in the oil pan and the crankcase internal pressure during warm-up in an internal combustion engine having a function capable of maintaining the crankcase internal pressure at a negative pressure when using 100% reference fuel. FIG. In an internal combustion engine equipped with a PCV device (blow-by gas reduction device) capable of maintaining the crankcase internal pressure at a negative pressure when using 100% reference fuel, as shown by a broken line in FIG. The crankcase internal pressure is maintained at a negative pressure regardless of the oil temperature rise. In the internal combustion engine having such a configuration, when different types of fuel (for example, methanol) are mixed at a high mixing ratio, the crankcase internal pressure is positive when the oil temperature becomes a value near the boiling point of the different types of fuel. become. Therefore, by detecting that the crankcase internal pressure has become positive when the oil temperature becomes a value near the boiling point of the different fuel, it may be determined that a large amount of the different fuel is contained.

Claims (1)

A pressure sensor for detecting the crankcase internal pressure;
An oil temperature sensor for detecting the oil temperature in the oil pan;
An internal combustion engine fuel property determination device comprising:
The relationship between the crankcase internal pressure and the oil temperature when the reference fuel is used during the engine warm-up period, and the oil temperature and crankcase internal pressure when the crankcase internal pressure reaches the maximum during the engine warm-up period And the crankcase internal pressure that occurs near the boiling point of the dissimilar fuel when the dissimilar fuel is mixed at a predetermined mixing ratio with respect to the reference fuel. A fuel property determination device for an internal combustion engine that estimates a mixing ratio of a different fuel to a reference fuel and a type of the different fuel based on a reference increase amount that is an increase amount of the fuel.

Images