JP4765720B2 - Fuel property detection device - Google Patents

Description

  The present invention relates to a fuel property detection device.

  In an internal combustion engine that can use a mixture of gasoline fuel and alcohol fuel as the mixed fuel, the proper ignition timing and fuel injection amount differ depending on the alcohol concentration in the mixed fuel. It is detected by a sensor (see, for example, Patent Document 1). The alcohol concentration in the mixed fuel can also be obtained in the process of feedback control of the fuel injection amount based on the air-fuel ratio obtained by the air-fuel ratio sensor.

By the way, when fuel with different alcohol concentrations is supplied at the time of refueling, the alcohol concentration in the fuel in the fuel tank may change suddenly after refueling. At this time, it takes a certain amount of time for the change in the alcohol concentration to appear in the output signal of the alcohol concentration sensor or the air-fuel ratio sensor. That is, there is a possibility that an appropriate ignition timing and fuel injection amount cannot be obtained until an accurate alcohol concentration is obtained based on the output of the alcohol concentration sensor or the air-fuel ratio sensor.
Japanese Patent Publication No. 6-100113 JP 2004-293491 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of quickly obtaining fuel properties after refueling in a fuel property detection device.

In order to achieve the above object, the fuel property detection apparatus according to the present invention employs the following means. That is, the fuel property detection device according to the present invention is:
A fuel property detection device for an internal combustion engine using a mixture of a plurality of fuels,
A fuel tank for storing fuel;
Fuel property detecting means for detecting the property of the fuel supplied to the internal combustion engine;
Fuel property storage means for storing the fuel property detected by the fuel property detection means before refueling;
Fuel remaining amount storage means for storing the amount of fuel remaining in the fuel tank before refueling;
Refueling determination means for determining whether or not fuel has been supplied to the fuel tank;
A fuel amount detecting means for detecting a fuel amount supplied to the fuel tank;
Assuming that each of the plurality of fuels is refueled, the fuel properties before refueling and the remaining fuel before refueling are assumed to be the properties of the fuel in the fuel tank after refueling when any of the plurality of fuels is refueled. Fuel property estimating means for estimating for each of a plurality of fuels based on the amount and the amount of fuel supply;
Fuel property determining means for determining which value is a true value from the respective estimated values estimated by the fuel property estimating means;
It is characterized by comprising.

  The internal combustion engine can use a mixture of a plurality of types of fuel as a mixed fuel. Examples of the plurality of types of fuels include alcohol and gasoline. The alcohol may be ether, methanol, or ethanol. A mixture obtained by mixing these fuels at a predetermined ratio can be considered as one of a plurality of types.

  The fuel property detection means detects, for example, the octane number or the predetermined fuel concentration, which is the property of the fuel.

  Prior to refueling, a sufficient time has elapsed since the previous refueling, so the fuel property inspection means can obtain an accurate fuel property. The fuel property thus detected is stored by the fuel property storage means.

  The remaining fuel amount storage means stores the amount of fuel in the fuel tank. The amount of fuel in the fuel tank is detected by, for example, a sensor.

  The fuel supply determination means can determine that the fuel supply has been performed, for example, when the amount of fuel in the fuel tank has increased.

  The fuel property estimation means estimates the fuel property after refueling for each type of fuel expected to be refueled. That is, since the fuel properties before refueling, the remaining fuel amount before refueling, and the amount of refueling are known as described above, if the properties of the fuel to be refueled are known, the fuel in the fuel tank after refueling Properties can be estimated. Here, although it is difficult to directly estimate the fuel property to be supplied with a sensor or the like, if the type of fuel to be supplied is known in advance, the fuel property after refueling can be estimated for each fuel. It becomes possible. That is, assuming that fuel is supplied for each of a plurality of fuels, the fuel properties after refueling can be estimated for each fuel. In this way, an estimated value of the number of all the fuels of a plurality of types can be obtained.

  The fuel property determination means determines which value is a true value among the fuel properties estimated by the fuel property estimation means.

  In the present invention, the fuel property determination means determines which of the estimated values estimated by the estimation means is a true value from the transition of the fuel property detected by the fuel property detection means after refueling. Can be determined.

  That is, it takes time until the fuel property detected by the fuel property detection means becomes an accurate value. However, the detected fuel property gradually changes toward an accurate value. The detected value during the gradual change varies depending on the type of fuel to be supplied. Then, the fuel property determination means determines which of the estimated fuel properties is a true value based on the transition of the detected value (for example, the amount of change in the fuel property per unit time).

  In the present invention, the fuel property determining means determines which of the estimated values estimated by the estimating means is a true value from the operating state of the internal combustion engine after refueling. Can do.

  Here, the optimum operating condition of the internal combustion engine also changes as the fuel properties change. That is, the optimum operating conditions are determined by the fuel properties. Exceeding this optimum operating condition will affect the operating state of the internal combustion engine. Therefore, the true fuel property after refueling can be determined based on the operating state of the internal combustion engine when engine control is performed according to the estimated fuel property after refueling.

Furthermore, in the present invention, the internal combustion engine uses a mixture of a plurality of fuels including at least alcohol,
The fuel property detection means detects the concentration of alcohol in the fuel supplied to the internal combustion engine,
The fuel property determination means can make a determination based on which fuel property estimated by the fuel property estimation means the alcohol concentration detected by the fuel property detection means is changing.

  As the fuel to be refueled, a fuel having 100% alcohol or a fuel in which alcohol and other fuel are mixed in advance at a predetermined ratio can be used.

  Here, the lower the alcohol concentration in the fuel to be supplied, the smaller the rate of increase of the alcohol concentration detected by the alcohol concentration sensor after refueling. Based on this, the fuel property determination means can estimate the actual alcohol concentration after refueling.

  According to the present invention, the fuel property after refueling can be obtained quickly.

  Hereinafter, specific embodiments of the fuel property detection device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine 1 to which a fuel property detection device according to the present embodiment is applied, and an intake system and an exhaust system thereof. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cycle engine. The internal combustion engine 1 can use a mixed fuel in which gasoline and alcohol are mixed at an arbitrary ratio.

  An intake passage 3 communicating with the cylinder 2 is connected to the internal combustion engine 1. A throttle 5 is provided in the middle of the intake passage 3.

  A fuel injection valve 6 that injects fuel into the intake passage 3 is attached to the intake passage 3 closer to the internal combustion engine 1 than the throttle 5. A fuel supply pipe 61 is connected to the fuel injection valve 6, and fuel flows in the fuel supply pipe 61. Further, an alcohol concentration sensor 62 for detecting the alcohol concentration of the fuel flowing through the fuel supply pipe 61 is attached to the fuel supply pipe 61. In this embodiment, the alcohol concentration sensor 62 corresponds to the fuel property detecting means in the present invention.

  The fuel supply pipe 61 is connected to a fuel pump 64 attached to the fuel tank 63. The fuel pump 64 discharges the fuel in the fuel tank 63 toward the fuel supply pipe 61. A remaining amount sensor 65 that outputs a signal corresponding to the amount of fuel in the fuel tank 63 is attached to the fuel tank 63. In addition, the fuel tank 63 is provided with a fuel filler port 66 that is opened to allow fuel to enter the fuel tank 63. The fuel is supplied into the fuel tank 63 from the fuel filler port 66.

  On the other hand, an exhaust passage 7 that leads to the cylinder 2 is connected to the internal combustion engine 1. An exhaust purification catalyst 8 is provided in the middle of the exhaust passage 7. Examples of the exhaust purification catalyst 8 include a three-way catalyst, an oxidation catalyst, and a NOx catalyst. An air-fuel ratio sensor 9 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing through the exhaust passage 7 is attached to the exhaust passage 7 downstream of the exhaust purification catalyst 8.

The internal combustion engine 1 configured as described above is provided with an ECU 10 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 10 controls the operation state of the internal combustion engine 1 according to the operation conditions of the internal combustion engine 1 and the request of the driver. The ECU 10 is connected to the sensors via electrical wiring, and the output signals of these sensors are input. On the other hand, the fuel injection valve 6 is connected to the ECU 10 through electric wiring, and the fuel injection valve 6 is controlled by the ECU 10.

  The ECU 10 stores the remaining amount of fuel that is the amount of fuel in the fuel tank 63. For example, the output value of the remaining amount sensor 65 is read every predetermined time and stored. In this embodiment, the ECU 10 that stores the remaining amount of fuel corresponds to the remaining fuel amount storage means in the present invention.

  Further, the ECU 10 stores the alcohol concentration obtained by the alcohol concentration sensor 62. For example, the output value of the alcohol concentration sensor 62 is read every predetermined time and stored. In this embodiment, the ECU 10 that stores the alcohol concentration corresponds to the fuel property storage means in the present invention.

  Further, the ECU 10 calculates the amount of fuel supplied by subtracting the remaining fuel amount before refueling from the remaining fuel amount after refueling. In this embodiment, the ECU 10 that calculates the amount of fuel supplied corresponds to the fuel amount detection means in the present invention. Further, when the remaining amount of fuel increases, it is determined that refueling has been performed. In this embodiment, the ECU 10 that makes such a determination corresponds to the fuel supply determination means in the present invention.

  Further, the ECU 10 stores the alcohol concentration of the fuel that is expected to be refueled. When gasoline fuel or alcohol fuel is expected to be supplied, the alcohol concentration in the gasoline fuel is 0% and the alcohol concentration in the alcohol fuel is 100%. In addition, when it is predicted that fuel with a predetermined alcohol concentration will be supplied in advance, the concentration is stored in advance.

  Next, an alcohol concentration estimation flow according to the present embodiment will be described. 2, 3 and 4 are flowcharts showing a flow for estimating the alcohol concentration according to the present embodiment. This routine is repeatedly executed every predetermined time. In this routine, the fuel to be supplied is either 100% gasoline or 100% alcohol.

  In step S101, it is determined whether or not the internal combustion engine 1 has just been started. In this step, it is determined whether or not this routine is executed only after the internal combustion engine 1 is started. Since the internal combustion engine 1 is often stopped during refueling, it is determined whether or not refueling has occurred.

  In addition, for example, whether or not the remaining amount of fuel has increased, or whether or not the lid covering the fuel filler 66 has been opened may be used as the determination condition.

  If an affirmative determination is made in step S101, the process proceeds to step S102, whereas if a negative determination is made, the process proceeds to step S105.

  In step S102, it is determined whether or not the difference between the current fuel remaining amount FP and the fuel remaining amount FO before the internal combustion engine 1 is stopped is equal to or greater than a predetermined value X.

  Even if refueling is performed, the alcohol concentration in the mixed fuel does not change so much and the influence on the operating state of the internal combustion engine 1 is small if the amount is small. On the other hand, when a certain amount of fuel is supplied, the operating state of the internal combustion engine 1 may be affected. In this step, it is determined whether or not the amount of fuel increases as the alcohol concentration in the fuel changes suddenly and the operating state of the internal combustion engine 1 changes. That is, the predetermined value X is a lower limit value of a value at which the alcohol concentration suddenly changes and the operating state of the internal combustion engine 1 may change. The remaining fuel amount FP at the present time, the remaining fuel amount FA before the internal combustion engine 1 is stopped, and the predetermined value X are stored in the ECU 10.

  If an affirmative determination is made in step S102, the process proceeds to step S103, whereas if a negative determination is made, this routine is temporarily terminated.

  In step S103, the alcohol concentration estimation flag FA is set to 1, and the alcohol concentration estimation counter CA is set to 0. The alcohol concentration estimation flag FA (hereinafter referred to as an estimation flag FA) is a flag that is set to 1 when it is necessary to estimate the alcohol concentration due to refueling. The alcohol concentration estimation counter CA (hereinafter referred to as the estimation counter CA) is a counter for counting the time spent for estimating the alcohol concentration.

  That is, since it is determined in the previous step that the alcohol concentration has changed suddenly, the alcohol concentration must be estimated in the subsequent processing. Therefore, the estimation flag FA is set to 1. In addition, since this step is a process that is performed for the first time after the internal combustion engine 1 is started, the alcohol concentration has not been estimated yet. Therefore, the estimation counter CA is set to 0.

  In step S104, the alcohol concentration AG in the fuel in the fuel tank 63 (hereinafter referred to as the gasoline concentration alcohol concentration AG) when it is assumed that gasoline fuel (that is, fuel with 0% alcohol) has been supplied is estimated. . Further, the alcohol concentration AA in the fuel in the fuel tank 63 when it is assumed that the alcohol fuel (that is, the fuel of 100% alcohol) is supplied is estimated (hereinafter referred to as alcohol concentration AA during alcohol supply).

  The alcohol concentration AO in the fuel before the internal combustion engine 1 is stopped, i.e., before refueling (hereinafter referred to as the alcohol concentration AO before refueling), the fuel remaining amount FO before the internal combustion engine 1 is stopped, i.e., before refueling, and the fuel amount, i. From the value obtained by subtracting the remaining fuel amount FO before refueling from the remaining fuel amount FP, the alcohol concentration AG during gasoline refueling is estimated.

Similarly, the alcohol concentration AA before alcohol supply from the alcohol concentration AO before refueling, the remaining fuel amount FO before refueling, and the value obtained by subtracting the remaining fuel amount FO before refueling from the refueling amount, that is, the remaining fuel amount FP after refueling. Is estimated.
In this embodiment, the ECU 10 that performs the process of step S104 corresponds to the fuel property estimating means in the present invention.

  In step S105, it is determined whether or not the estimation flag FA is 1. That is, it is determined whether it is necessary to estimate the alcohol concentration in the mixed fuel.

  If an affirmative determination is made in step S105, the process proceeds to step S106, and if a negative determination is made, this routine is temporarily terminated.

  In step S106, the estimation counter CA is counted up. That is, since the alcohol concentration is estimated in the subsequent steps, 1 is added to the estimation counter CA.

  In step S107, it is determined whether or not the estimation counter CA is equal to or greater than a predetermined value A. If a certain amount of time has elapsed after refueling, the alcohol concentration sensor 62 or the air-fuel ratio sensor 9 can detect the alcohol concentration. In such a case, it is not necessary to detect the alcohol concentration by this routine, so this routine is terminated. That is, the predetermined value A is an upper limit value of the value of the estimation counter CA that requires estimation of the alcohol concentration.

  If an affirmative determination is made in step S107, the process proceeds to step S108, whereas if a negative determination is made, the process proceeds to step S112.

  In step S108, it is determined whether or not the difference between the current alcohol concentration AP and the alcohol concentration AO before refueling is equal to or greater than a predetermined value B. In this step, it is determined whether or not the alcohol concentration has increased by a predetermined value B or more due to refueling, that is, whether or not the alcohol concentration is high. The predetermined value B is set in consideration of detection variations of the alcohol concentration sensor 62 and the like. When the alcohol concentration is high, there is a high possibility that the alcohol fuel has been supplied. However, even if gasoline fuel is supplied, the detected value of the alcohol concentration may temporarily increase depending on the detection variation of the alcohol concentration sensor 62 and the fuel mixing state. Therefore, in this routine, it is determined that the alcohol fuel has been supplied when the alcohol concentration continuously increases.

  If an affirmative determination is made in step S108, the process proceeds to step S109, whereas if a negative determination is made, the process proceeds to step S113.

  In step S109, the alcohol concentration increase counter CI is counted up and the alcohol concentration decrease counter CD is set to zero.

  The alcohol concentration increase counter CI is a counter that is counted when an increase in alcohol concentration is detected, and the alcohol concentration decrease counter CD is a counter that is counted when a decrease in alcohol concentration is detected.

  In this step, since the alcohol concentration has increased, 1 is added to the alcohol concentration increase counter CI, and the alcohol concentration decrease counter CD is set to 0.

  In step S110, it is determined whether or not the value of the alcohol concentration increase counter CI is equal to or greater than a predetermined value C. In this step, it is determined whether or not the alcohol concentration continuously increases for a predetermined time. If the alcohol concentration increases continuously for a predetermined time, it cannot be considered that the detection value of the alcohol concentration sensor 62 increases due to the detection variation of the alcohol concentration sensor 62 or the influence of the fuel mixing state. That is, it can be determined that the fuel supplied is alcohol fuel. That is, the predetermined value C is set as the time required for determining that the fuel supplied is alcohol fuel.

  If an affirmative determination is made in step S110, the process proceeds to step S111, whereas if a negative determination is made, this routine is temporarily terminated.

  In step S111, the alcohol concentration AA during alcohol supply is substituted for the alcohol concentration AL after refueling.

  In step S112, the estimation flag FA is set to 0, and then this routine is once ended.

In step S113, it is determined whether or not the difference between the alcohol concentration AO before refueling and the current alcohol concentration AP is a predetermined value D or more. In this step, it is determined whether or not the alcohol concentration has decreased by a predetermined value D or more due to refueling, that is, whether or not the alcohol concentration is low. The predetermined value D is set in consideration of detection variations of the alcohol concentration sensor 62 and the like. When the alcohol concentration is low, there is a high possibility that gasoline fuel has been refueled. However, even when the alcohol fuel is supplied, the detected value of the alcohol concentration may be temporarily lowered depending on the detection variation of the alcohol concentration sensor 62 and the mixed state of the fuel. Therefore, in this routine, it is determined that gasoline fuel has been refueled when the alcohol concentration continuously decreases.

  If an affirmative determination is made in step S113, the process proceeds to step S114, whereas if a negative determination is made, this routine is temporarily terminated.

  In step S114, the alcohol concentration increase counter CI is set to 0, and the alcohol concentration decrease counter CD is counted up.

  In this step, since the alcohol concentration has decreased, 1 is added to the alcohol concentration decrease counter CD, and the alcohol concentration increase counter CI is set to 0.

  In step S115, it is determined whether or not the value of the alcohol concentration reduction counter CD is equal to or greater than a predetermined value E. In this step, it is determined whether or not the alcohol concentration has decreased continuously for a predetermined time. If the alcohol concentration decreases continuously for a predetermined time, it cannot be considered that the detection value of the alcohol concentration sensor 62 decreases due to the detection variation of the alcohol concentration sensor 62 or the influence of the fuel mixing state. That is, it can be determined that the fuel supplied is gasoline fuel. That is, the predetermined value E is set as the time required for determining that the fuel supplied is gasoline fuel.

  If an affirmative determination is made in step S115, the process proceeds to step S116, whereas if a negative determination is made, this routine is temporarily terminated.

  In step S116, the gasoline concentration alcohol concentration AG is substituted into the alcohol concentration AL after refueling. Thereafter, the process proceeds to step S112.

  In this manner, the actual alcohol concentration after refueling can be estimated even when the value of the alcohol concentration sensor 62 is changing after refueling. As a result, the ignition timing and the fuel injection amount can be promptly set to appropriate values, so that the operating state of the internal combustion engine 1 can be kept good. In this embodiment, the ECU 10 that performs the processing from step S108 to step S116 corresponds to the fuel property determination means in the present invention.

  In this embodiment, the alcohol concentration in the mixed fuel after either one of gasoline fuel or alcohol fuel is supplied is estimated. However, the present invention is not limited to this. The present invention can also be employed when refueling fuel that has been mixed in advance at a predetermined ratio. Also, alcohol or gasoline may be another fuel.

  Furthermore, in the present embodiment, the alcohol concentration is estimated when the detection value of the alcohol concentration sensor 62 continuously increases or decreases, but the present invention is not limited to this. The actual alcohol concentration may be estimated based on the alcohol concentration detected by the alcohol concentration sensor 62 when it has elapsed. Further, the actual alcohol concentration may be estimated based on the change rate of the alcohol concentration detected by the alcohol concentration sensor 62.

  Further, the actual alcohol concentration can be estimated without using the detection value of the alcohol concentration sensor 62 after refueling. For example, the relationship between the engine speed, the engine load, and the alcohol concentration is obtained and mapped in advance by experiments or the like, and the internal combustion engine 1 is controlled assuming that the fuel supplied is alcohol fuel. If torque fluctuation or rotation fluctuation does not occur at this time, the supplied fuel can be determined as alcohol fuel, and if torque fluctuation or rotation fluctuation occurs, the supplied fuel can be determined as gasoline fuel.

  As described above, according to the present embodiment, the alcohol concentration after refueling is estimated on the assumption that fuel is supplied for each of the fuels that are predicted to be refueled. Based on the detected transition of the alcohol concentration, it can be determined to which estimated value the detected value is moving. As a result, the actual alcohol concentration can be quickly estimated, so that the internal combustion engine 1 can be appropriately controlled.

It is a figure which shows schematic structure of the internal combustion engine to which the fuel property detection apparatus based on an Example is applied, and its intake system and exhaust system. It is the flowchart which showed the flow for estimating the alcohol concentration which concerns on an Example. It is the flowchart which showed the flow for estimating the alcohol concentration which concerns on an Example. It is the flowchart which showed the flow for estimating the alcohol concentration which concerns on an Example.

Explanation of symbols

1 Internal combustion engine 2 Cylinder 3 Intake passage 5 Throttle 6 Fuel injection valve 7 Exhaust passage 8 Exhaust purification catalyst 9 Air-fuel ratio sensor 10 ECU
61 Fuel supply pipe 62 Alcohol concentration sensor 63 Fuel tank 64 Fuel pump 65 Remaining amount sensor 66 Refueling port

Claims (4)

A fuel property detection device for an internal combustion engine using a mixture of a plurality of fuels,
A fuel tank for storing fuel;
Fuel property detecting means for detecting the property of the fuel supplied to the internal combustion engine;
Fuel property storage means for storing the fuel property detected by the fuel property detection means before refueling;
Fuel remaining amount storage means for storing the amount of fuel remaining in the fuel tank before refueling;
Refueling determination means for determining whether or not fuel has been supplied to the fuel tank;
A fuel amount detecting means for detecting a fuel amount supplied to the fuel tank;
Assuming that each of the plurality of fuels is refueled, the fuel properties before refueling and the remaining fuel before refueling are assumed to be the properties of the fuel in the fuel tank after refueling when any of the plurality of fuels is refueled. Fuel property estimating means for estimating for each of a plurality of fuels based on the amount and the amount of fuel supply;
Fuel property determining means for determining which value is a true value from the respective estimated values estimated by the fuel property estimating means;
A fuel property detection device comprising:   The fuel property determining means determines which of the estimated values estimated by the estimating means is a true value from the transition of the fuel property detected by the fuel property detecting means after refueling. The fuel property detection device according to claim 1, wherein   2. The fuel property determining means determines which of the estimated values estimated by the estimating means is a true value from the operating state of the internal combustion engine after refueling. The fuel property detection device according to 1. The internal combustion engine uses a mixture of a plurality of fuels including at least alcohol,
The fuel property detection means detects the concentration of alcohol in the fuel supplied to the internal combustion engine,
The fuel property determination means makes a determination based on which fuel property the alcohol concentration detected by the fuel property detection means is estimated to be shifted toward the fuel property estimation means. The fuel property detection device according to claim 1 or 2.

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