JP2009036032A - Different fuel mixing determination device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the mixing of different fuel when unusable different fuel is mixed in fuel supplied to an engine. <P>SOLUTION: When the different fuel (such as light oil, kerosene, and heavy oil) is mixed in the fuel (such as gasoline) supplied to the engine, a combustion state is deteriorated, and cylinder pressure is lowered. Therefore, an integrated cylinder pressure value calculated from the cylinder pressure is reduced, and comes out of a predetermined normal range (such as the range of the integrated cylinder pressure value when normal fuel is supplied). According to these characteristics, the integrated cylinder pressure value is calculated from the cylinder pressure detected by a cylinder pressure sensor, and it is determined whether the integrated cylinder pressure value comes out of the normal range or not. When the integrated cylinder pressure value comes out of the normal range, it is determined that the different fuel (such as light oil, kerosene, and heavy oil) is mixed in the fuel. Also, the mixed ratio of the different fuel is estimated by calculating the mixed ratio of the different fuel according to the integrated cylinder pressure value by a map or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine heterogeneous fuel mixture determination device having a function of determining whether or not a heterogeneous fuel is mixed in the fuel supplied to the internal combustion engine.

Since the properties of the fuel used in the internal combustion engine may vary depending on the region, season, etc., as described in Japanese Patent Application Laid-Open No. 2000-356163, it is obtained from the in-cylinder pressure of the internal combustion engine. In some cases, the fuel evaporation characteristic (fuel property) is determined based on the indicated mean effective pressure, and the fuel injection amount and the ignition timing are corrected in accordance with the fuel evaporation characteristic.
JP 2000-356163 A (second page, etc.)

  By the way, the internal combustion engine includes a gasoline engine using gasoline and a diesel engine using light oil. In recent years, since the number of self-stands where the driver refuels himself / herself is increasing, there is a possibility that the driver will accidentally refuel the gasoline engine vehicle with light oil, which is a different kind of unusable fuel. Moreover, there is a possibility that poor fuel obtained by intentionally mixing different fuels such as light oil and kerosene into gasoline is supplied. Gasoline evaporation characteristics (fuel properties) may vary depending on the region, season, etc., but it is normal even if gasoline with different evaporation properties (fuel properties) is supplied to a gasoline engine vehicle using the technology disclosed in Patent Document 1 above. It is now possible to drive.

  On the other hand, even if different types of fuel such as light oil and kerosene and poor fuel are supplied to the gasoline engine vehicle, the fuel is supplied with some gasoline remaining in the fuel tank. If the mixing ratio of dissimilar fuel to gasoline in the fuel tank is small, the engine can be operated by ignition timing control or the like. However, as the mixing ratio of dissimilar fuel increases, the combustion state of the engine deteriorates. Not only does the engine rotation become unstable and drivability deteriorates, but in the worst case, the engine may stop and become unable to run.

  Even if different types of fuel or poor fuel are supplied with almost no gasoline remaining in the fuel tank, the gasoline remaining in the fuel pipe from the fuel tank to the engine is supplied to the engine at first. When the engine can be operated normally for a while and then there is no gasoline remaining in the fuel pipe and different fuel or poor fuel is injected, the combustion state of the engine deteriorates and the engine rotation starts. The engine may become unstable, and in the worst case, the engine may stop and become unable to run.

  The present invention has been made in view of such circumstances. Accordingly, the object of the present invention is to provide a method for the use of different types of fuel when the fuel supplied to the internal combustion engine contains unusable different types of fuel. An object of the present invention is to provide an apparatus for determining mixing of different types of fuel in an internal combustion engine capable of detecting mixing.

  In order to achieve the above object, the invention according to claim 1 is provided with in-cylinder pressure determination means for detecting or estimating the in-cylinder pressure of the internal combustion engine, and the in-cylinder pressure detected or estimated by the in-cylinder pressure determination means. Based on this, it is determined by the different fuel mixture determination means whether or not the different fuel is mixed in the fuel supplied to the internal combustion engine.

  If unusable dissimilar fuel is mixed in the fuel supplied to the internal combustion engine, the combustion state changes and the in-cylinder pressure changes. Therefore, if the in-cylinder pressure is used, it is accurately determined whether or not the dissimilar fuel is mixed. It can be determined, and when a different fuel is mixed, the mixing of the different fuel can be detected. As a result, when different types of fuel are mixed, it becomes possible to detect the mixing of the different types of fuel and notify the driver with a warning lamp or the like, so that the driver can immediately take measures such as changing the fuel. Can be urged. In addition, when different types of fuel are mixed, the control of the internal combustion engine can be switched to the control for mixing different types of fuel so that the vehicle can travel safely for as long as possible.

  In this case, as described in claim 2, when it is determined that the different fuel is mixed, the mixing ratio of the different fuel is determined based on the in-cylinder pressure detected or estimated by the in-cylinder pressure determining means. You may make it estimate by an estimation means. Generally, since the in-cylinder pressure changes due to the change in the combustion state according to the mixing ratio of the different fuel, the mixing ratio of the different fuel can be estimated by using the in-cylinder pressure. As a result, when the control of the internal combustion engine is switched to the control for mixing different types of fuel, it is possible to perform appropriate control according to the mixing ratio of different types of fuel.

  The present invention is applied to a gasoline engine that uses gasoline as a fuel as in claim 3 to determine whether or not at least one of light oil, kerosene, and heavy oil is mixed as a different fuel. Also good. In this way, when light oil, kerosene, or heavy oil is mixed in gasoline supplied to the gasoline engine, it is possible to detect mixing of the light oil, kerosene, or heavy oil.

Hereinafter, an embodiment in which the best mode for carrying out the present invention is applied to a gasoline engine (an engine using gasoline as fuel) will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 that detects the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake manifold 20 for introducing air into each cylinder of the engine 11 is provided in the surge tank 18. A fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  A cooling water temperature sensor 26 that detects the cooling water temperature and a knock sensor 29 that detects knocking are attached to the cylinder block of the engine 11. A crank angle sensor 28 that outputs a pulse signal every time the crankshaft 27 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 27. Based on the output signal of the crank angle sensor 28, the crank angle and engine The rotation speed is detected.

  Further, the cylinder head of the engine 11 is provided with an in-cylinder pressure sensor 39 (in-cylinder pressure determining means) for detecting the in-cylinder pressure for each cylinder (or only a specific cylinder). This in-cylinder pressure sensor 39 may be of a type integrated with the spark plug 22 or a type of sensor that is mounted so that a sensor part separate from the spark plug 22 faces the combustion chamber. Also good.

  A fuel pump 31 that pumps up fuel is provided in a fuel tank 30 that stores fuel (gasoline). The fuel discharged from the fuel pump 31 is sent to the delivery pipe 33 through the fuel pipe 32 and is distributed from the delivery pipe 33 to the fuel injection valve 21 of each cylinder. A filter 34 and a pressure regulator 35 are connected in the vicinity of the fuel pump 31 in the fuel pipe 32, and the discharge pressure of the fuel pump 31 is adjusted to a predetermined pressure by the pressure regulator 35. Is returned to the fuel tank 30 by the fuel return pipe 36.

  The outputs of the various sensors described above are input to a control circuit (hereinafter referred to as “ECU”) 37. The ECU 37 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 21 can be changed according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

  By the way, even if different types of fuel such as light oil or kerosene or poor fuel mixed with different types of fuel is supplied to the vehicle of the gasoline engine 11, gasoline is supplied in a state where some gasoline remains in the fuel tank 30. In such an electronically controlled engine control system, the engine 11 can be operated by ignition timing control or the like if the mixing ratio of the different fuel to the gasoline in the fuel tank 30 is small. As the ratio increases, not only the combustion state of the engine deteriorates but the engine rotation becomes unstable, the drivability deteriorates, and in the worst case, the engine 11 may stop and become unable to run.

  Therefore, the ECU 37 executes a heterogeneous fuel mixture determination routine shown in FIG. 3 to be described later, thereby disabling dissimilar fuel (light oil) that cannot be used as fuel supplied to the engine 11 based on the in-cylinder pressure detected by the in-cylinder pressure sensor 39. , At least one of kerosene, heavy oil, etc.) is determined.

  Specifically, when the fuel supplied to the engine 11 is mixed with different types of fuel such as light oil, kerosene, and heavy oil, the combustion state deteriorates and the in-cylinder pressure decreases. As shown in the chart, based on the in-cylinder pressure detected by the in-cylinder pressure sensor 39, the integrated value of the in-cylinder pressure in a predetermined period (for example, the compression stroke and the explosion stroke) is calculated, and this in-cylinder pressure integrated value is It is determined whether or not it is outside the normal range (for example, the range of the in-cylinder pressure integrated value when normal gasoline is supplied), and when it is determined that the in-cylinder pressure integrated value is out of the normal range, It is determined that (light oil, kerosene, heavy oil, etc.) is mixed. Accordingly, it can be accurately determined whether or not the different fuel is mixed, and when the different fuel is mixed, the mixing of the different fuel can be detected promptly.

  Further, paying attention to the characteristic that the in-cylinder pressure integrated value changes due to the change in the combustion state according to the mixing ratio of the different fuel, the in-cylinder pressure integrated value is determined when it is determined that the different fuel is mixed. The mixing ratio of the different fuel is estimated by calculating the mixing ratio of the different fuel according to the map (see FIG. 4) or a mathematical formula.

  The heterogeneous fuel mixture determination of the present embodiment described above is executed by the ECU 37 according to the heterogeneous fuel mixture determination routine of FIG. The processing contents of this routine will be described below.

  The heterogeneous fuel mixture determination routine shown in FIG. 3 is executed at a predetermined cycle while the ECU 37 is turned on, and serves as a heterogeneous fuel mixture determination means in the claims. When this routine is started, first, in step 101, the in-cylinder pressure detected by the in-cylinder pressure sensor 39 is read, and then the routine proceeds to step 102 where the in-cylinder pressure in a predetermined period (for example, compression stroke and explosion stroke) is detected. Calculate the integrated value.

  Thereafter, the process proceeds to step 103, and whether or not the in-cylinder pressure integrated value is out of the normal range (whether or not the in-cylinder pressure integrated value is larger than the upper limit side determination value or smaller than the lower limit side determination value). judge. Here, the upper limit side determination value is set to, for example, the upper limit value of the in-cylinder pressure integrated value when normal fuel (gasoline) is supplied, and the lower limit side determination value is, for example, normal fuel (gasoline) Is set to the lower limit value of the in-cylinder pressure integrated value when. In this case, the determination values (upper limit determination value and lower limit determination value) may be changed according to the engine operating state (for example, engine rotation speed, load, etc.). Accordingly, the determination value is appropriately changed in response to the change in the in-cylinder pressure and the change in the in-cylinder pressure according to the engine operating state.

  If it is determined in step 103 that the in-cylinder pressure integrated value is within the normal range (the in-cylinder pressure integrated value is within the range from the upper limit side determination value to the lower limit side determination value), the process proceeds to step 104, where light oil, It is determined that there is no mixing of different types of fuel such as kerosene and heavy oil, and this routine is terminated.

  On the other hand, in step 103, it is determined that the in-cylinder pressure integrated value is out of the normal range (the in-cylinder pressure integrated value is larger than the upper limit side determination value or smaller than the lower limit side determination value). For example, after proceeding to step 105 and determining that there is a mixture of different types of fuel (light oil, kerosene, heavy oil, etc.), proceed to step 106 and turn on the different fuel mixture warning lamp 38 provided on the instrument panel of the driver's seat. Alternatively, a warning display section (not shown) on the instrument panel of the driver's seat warns the driver by displaying a warning of “mixing of different types of fuel”. As a result, the driver is informed early of the mixing of different fuels.

  Thereafter, the process proceeds to step 107, where the mixture ratio of the different fuel is calculated according to the current integrated value of the in-cylinder pressure with reference to the map of the mixture ratio of the different fuel shown in FIG. Since the in-cylinder pressure tends to decrease and the in-cylinder pressure integrated value tends to decrease as the mixing ratio of different fuel increases, the map of the mixing ratio of different fuel shown in FIG. 4 shows that the in-cylinder pressure integrated value decreases. It is set so that the mixing ratio of different types of fuel becomes high. The processing in step 107 serves as a different fuel mixture ratio estimation means in the claims.

  Thereafter, the routine proceeds to step 108 where the operation control of the engine 11 (for example, at least one of fuel injection control, throttle control, torque control, air-fuel ratio control, idle rotation speed control, etc.) is controlled for mixing different types of fuel. To ensure that the vehicle can travel safely for as long as possible. At this time, by performing the control for mixing different fuels according to the mixing ratio of different fuels, appropriate control is performed according to the mixing ratio of different fuels.

  In the present embodiment described above, focusing on the characteristic that when the diesel fuel supplied to the engine 11 is mixed with light oil, kerosene, heavy oil, etc., the combustion state deteriorates and the in-cylinder pressure decreases, It is determined whether or not the obtained in-cylinder pressure integrated value is out of the normal range, and when it is determined that the in-cylinder pressure integrated value is out of the normal range, different types of fuel (light oil, kerosene, heavy oil, etc.) are mixed Therefore, it is possible to accurately determine whether or not the different fuel is mixed, and when the different fuel is mixed, it is possible to quickly detect the mixing of the different fuel. . As a result, when different types of fuel are mixed, it becomes possible to notify the driver of the mixing of the different types of fuel with the different types of fuel mixing warning lamp 38 or the like, so that the driver can be promptly replaced. Can be encouraged. Further, when different types of fuel are mixed, the control of the engine 11 can be switched to the control for mixing different types of fuel so that the vehicle can travel safely as long as possible.

  Furthermore, in this embodiment, paying attention to the characteristic that the combustion state changes according to the mixing ratio of the different fuel and the in-cylinder pressure integrated value changes, when it is determined that the different fuel is mixed, Since the mixing ratio of different fuels is estimated based on the in-cylinder pressure integrated value, the mixing ratio of different fuels can be accurately estimated. Thereby, when the control of the engine 11 is switched to the control for mixing different types of fuel, it is possible to perform appropriate control according to the mixing ratio of different types of fuel.

  However, it is needless to say that the present invention may be configured not to estimate the mixing ratio of different fuels when it is determined that different fuels are mixed.

  Further, in the above embodiment, it is determined whether or not the different fuel is mixed depending on whether or not the in-cylinder pressure integrated value is out of the normal range, but the determination method of the different fuel mixing is appropriately changed. For example, the indicated mean effective pressure obtained from the in-cylinder pressure in the predetermined period, the maximum value (peak value) of the in-cylinder pressure in the predetermined period, the change rate of the in-cylinder pressure in the predetermined period, etc. are out of the predetermined normal range. Whether or not different types of fuel are mixed may be determined based on whether or not the fuel is mixed.

  Alternatively, the variation (for example, standard deviation) and the amount of change of these determination parameters (the integrated value of the in-cylinder pressure, the indicated mean effective pressure, the maximum value of the in-cylinder pressure, the change speed of the in-cylinder pressure, and the like) are compared with the determination value. Then, it may be determined whether or not different types of fuel are mixed.

  In the above embodiment, it is determined whether or not light oil, kerosene, or heavy oil is mixed in the gasoline supplied to the engine 11 as a different type of fuel. It may be determined whether or not.

  Further, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, and includes an in-cylinder injection type engine, and a fuel injection valve for intake port injection and a fuel injection valve for in-cylinder injection. It can also be applied to dual-injection engines.

  Further, the present invention is applied to a diesel engine that uses light oil as a fuel, and it is determined whether or not gasoline, which is a different kind of unusable fuel, is mixed in the light oil supplied to the engine based on the in-cylinder pressure. Anyway.

  In addition, the present invention is applied to a bi-fuel engine that can use any gasoline, alcohol, and alcohol mixed fuel obtained by mixing alcohol with gasoline as fuel, and cannot be used for fuel supplied to the engine based on in-cylinder pressure. It may be determined whether or not light oil, kerosene, heavy oil, etc., which are different types of fuels, are mixed.

  In the above embodiment, the in-cylinder pressure is detected by the in-cylinder pressure sensor 39. However, the in-cylinder pressure is calculated by a map or a mathematical formula based on the engine operating state (for example, the engine speed or load). Thus, the in-cylinder pressure may be estimated.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a time chart explaining the determination method of heterogeneous fuel mixing. It is a flowchart explaining the flow of a process of a different fuel mixing determination routine. It is a figure which shows notionally an example of the map of a different fuel mixing ratio.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 30 ... Fuel tank, 31 ... Fuel pump, 32 ... Fuel piping, 37 ... ECU (different fuel mixture determination means, different fuel mixture ratio estimation means), 38 ... different fuel mixture warning lamp, 39 ... cylinder pressure sensor (cylinder pressure determination means)

Claims (3)

In-cylinder pressure determining means for detecting or estimating the in-cylinder pressure of the internal combustion engine;
Different fuel mixture determination means for determining whether or not different fuel is mixed in the fuel supplied to the internal combustion engine based on the in-cylinder pressure detected or estimated by the in-cylinder pressure determination means. A heterogeneous fuel mixing determination device for an internal combustion engine.   A heterogeneous fuel that estimates the mixing ratio of the different fuel based on the in-cylinder pressure detected or estimated by the in-cylinder pressure determining means when the heterogeneous fuel mixing determining means determines that the different fuel is mixed. 2. The heterogeneous fuel mixing determination apparatus for an internal combustion engine according to claim 1, further comprising a mixing ratio estimation unit. The internal combustion engine is a gasoline engine that uses gasoline as fuel,
3. The internal combustion engine heterogeneity according to claim 1, wherein the heterogeneous fuel mixture determination unit determines whether at least one of light oil, kerosene, and heavy oil is mixed as the heterogeneous fuel. Fuel mixing determination device.

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