JP2011052624A - Fuel property identification means for fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly calculate a mixing ratio (mixed quantity) of fuel containing oxygen organic substances used for driving an engine, and to perform air-fuel ratio control ensuring high exhaust emission control performance based on the obtained mixing ratio. <P>SOLUTION: This fuel property identification means for a fuel injection control device includes: a characteristic line map representing characteristics of a theoretical air-fuel ratio and an ethanol mixing ratio in fuel; and an air-fuel ration calculation means calculating an air-fuel ratio from a detected intake air volume and the calculated amount of fuel injected. During performance of λ feedback correction control when a second predetermined condition is satisfied, a step of calculating the present air-fuel ratio of fuel, a step of calculating the present ethanol mixing ratio in fuel by comparing the obtained present air-fuel ratio of fuel with the characteristic line map, and a step of storing the present ethanol mixing ratio in fuel are performed. After that, when the first predetermined condition is satisfied, the feedback correction control over the amount of fuel injected is performed by the use of the present ethanol mixing ratio in fuel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel property identification unit of a fuel injection control device, and more particularly to a fuel control control device for an engine using fuels having different properties, and capable of accurately determining a mixture ratio of a fuel containing oxygen organic matter. The present invention relates to a fuel property identifying means of the apparatus.

In an engine mounted on a vehicle, gasoline is supplied by a fuel injection control device, and bioethanol is attracting attention as a fuel that replaces gasoline. Since CO ₂ emissions from bioethanol combustion are essentially carbon neutral (carbon emissions are zero), bioethanol is used instead of gasoline to reduce global CO ₂ emissions. This is extremely useful.
However, when a fuel that is a mixture of gasoline and ethanol is used, the boiling point of ethanol is 78 ° C, which is much higher than the initial boiling point of general gasoline, which may adversely affect operability when the engine is cold. It is done. Therefore, it is very important to determine the properties of the fuel supplied to the engine and know in advance the amount of ethanol mixed in the gasoline. If the amount of ethanol in the fuel is known in advance, problems will not occur. Therefore, it is possible to set a fuel injection amount corresponding to the above, and to prevent the above-mentioned problems in advance.
Conventional means for determining fuel properties include those using an alcohol concentration sensor (Patent Document 1) and those calculated from a shift (shift) in the output value of an air-fuel ratio sensor (Patent Document 2).

JP-A-4-255543 JP 2008-95662 A

However, in patent document 1, since the alcohol concentration sensor is used, there exists a problem which requires cost. Further, in Patent Document 2, since the ethanol mixing ratio is estimated from the shift value (deviation amount) of the output value of the air-fuel ratio sensor, it is not accurate to know the absolute value of the ethanol mixing amount, and O _2. There is a difficulty in a fuel injection control device using a sensor.

  The present invention accurately calculates the mixing ratio (amount) of the fuel containing oxygen organic substances used for driving the engine, and performs air-fuel ratio control that ensures high exhaust gas purification based on the obtained mixing ratio. The aim is to be able to do it.

  The present invention includes an intake air amount detection means, a fuel injection amount calculation means, and an exhaust gas component detection means, and based on the detected exhaust gas component, the fuel injection amount when the first predetermined condition is satisfied. In the fuel property identification means of the fuel injection control device that performs λ feedback correction control of the fuel injection amount when another second predetermined condition is satisfied, the stoichiometric ratio and the fuel ethanol mixing ratio are A characteristic line map showing the characteristics of the air-fuel ratio, and an air-fuel ratio calculating means for calculating a fuel air-fuel ratio from the detected intake air amount and the calculated fuel injection amount is provided. While executing the λ feedback correction control when the condition is satisfied, the step of calculating the air-fuel ratio of the current fuel by the air-fuel ratio calculating means, and the obtained air fuel ratio of the current fuel The step of calculating the ethanol mixture ratio of the current fuel in comparison and the step of storing the ethanol mixture ratio of the current fuel are performed. After that, when the first predetermined condition is satisfied, the ethanol mixture ratio of the current fuel is used. It is characterized by performing feedback correction control of the fuel injection amount.

The fuel property identifying means of the fuel injection control device according to the present invention performs the fuel property determination during the execution of the λ feedback correction control targeting the theoretical air-fuel ratio, so that no dedicated alcohol concentration detecting means is provided. The fuel properties, especially the ethanol mixing ratio can be grasped. Thereafter, optimal fuel injection control can be performed according to the grasped ethanol mixture ratio.
Further, since the fuel property identification means of the fuel injection control device of the present invention uses a characteristic line map, even if the fuel property changes suddenly due to refueling or the like, even if the ethanol mixture ratio changes greatly, the fuel Updates to changes in properties can be made faster. By entering the operating state in which λ feedback correction control is performed at a relatively early stage after refueling, the amount of exhaust gas harmful components that have deteriorated during traveling can be suppressed.

It is a flowchart of the ethanol mixing ratio calculation of a fuel. (Example) It is a flowchart of feedback correction control using ethanol mixing ratio. (Example) It is a figure which shows the characteristic line map of a theoretical air ratio and the ethanol mixing ratio of a fuel. (Example) It is a system configuration figure of a fuel injection control device. (Example)

This invention calculates and stores the current fuel ethanol mixture ratio by comparing the current fuel air-fuel ratio with the characteristic line map of the theoretical air-fuel ratio and the fuel ethanol mixture ratio during the λ feedback correction control. Then, feedback correction control of the fuel injection amount is performed using the ethanol mixing ratio of the current fuel.
Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 show an embodiment of the present invention. In FIG. 4, 1 is an engine, 2 is a cylinder block, 3 is a cylinder head, 4 is a cylinder head cover, and 5 is a piston. The engine 1 includes an intake port 7 and an exhaust port 8 communicating with the combustion chamber 6, an intake valve 9 and an exhaust valve 10 that open and close the intake port 7 and the exhaust port 8, respectively, and opens and closes the intake valve 9 and the exhaust valve 10. An intake camshaft 11 and an exhaust camshaft 12 are provided.
In the engine 1, an air cleaner 13, an intake pipe 14, a throttle body 15, a surge tank 16 and an intake manifold 17 are sequentially connected, and an intake passage 18 communicating with the intake port 7 is provided. A throttle valve 19 is provided in the intake passage 18 of the throttle body 15. Further, the engine 1 is provided with an exhaust passage 24 that sequentially connects the exhaust manifold 20, the first catalyst 21, the exhaust pipe 22, and the second catalyst 23 and communicates with the exhaust port 8.
The engine 1 is provided with a bypass air passage 25 that bypasses the throttle valve 19 and communicates with the intake passage 18. An idle air amount control valve 26 for adjusting the amount of idle air to the engine 1 is provided in the middle of the bypass air passage 25.
Further, the engine 1 is provided with an EGR passage 27 having one end side communicating with the exhaust passage 24 of the exhaust manifold 20 and the other end side communicating with the intake passage 18 of the surge tank 16. In the middle of the EGR passage 27, an EGR control valve 28 for controlling the flow rate of the exhaust gas returning to the intake passage 18 is provided.
Further, the engine 1 has a spark plug 29 attached to the cylinder head 3 so as to face the combustion chamber 6, and an ignition coil 30 that causes the spark plug 29 to ignite is attached to the cylinder head cover 4. Further, the engine 1 is provided with a tank side blow-by gas pipe 32 communicating with the intake passage 18 of the surge tank 16 through the PCV valve 31 in the cylinder head cover 4, and communicating with the intake passage 18 of the throttle body 15 in the cylinder head cover 4. A body side blow-by gas pipe 33 is provided.

The engine 1 is provided with a fuel tank 34 for storing gasoline or ethanol used as fuel. A fuel pump 35 for pumping fuel is provided in the fuel tank 34, and one end of a fuel supply pipe 36 is connected to the fuel pump 35. The fuel supply pipe 36 is provided with a filter 37 in the middle, and the other end side is connected to the delivery pipe 38. A fuel injection valve 39 for each cylinder attached to the cylinder head 3 is connected to the delivery pipe 38. The fuel injection valve 39 is attached to the cylinder head 3 so as to face the intake port 7 and injects fuel toward the combustion chamber 6.
The fuel supply pipe 36 is provided with a pressure regulator 40 that adjusts the fuel pressure. The pressure regulator 40 introduces pressure from the intake passage 18 of the surge tank 16 through the pressure introduction pipe 41 to adjust the fuel pressure in the fuel supply pipe 36, and returns excess fuel to the fuel tank 34 through the fuel return pipe 42.
The idle air amount control valve 26, the EGR control valve 28, the ignition coil 30, the fuel pump 35 and the fuel injection valve 39 are connected to the fuel control unit 44 of the fuel injection control device 43. The fuel control unit 44 connects an intake air temperature sensor 45 that is an intake air temperature detection unit, an air flow sensor 46 that is an intake air amount detection unit, and an O ₂ sensor 47 that is an exhaust gas component detection unit, A fuel injection amount calculation means 48 and a storage means 49 for storing data are provided. The fuel control unit 44 receives various sensor signals, performs feedback correction control of the fuel injection amount when the first predetermined condition is satisfied, based on the detected oxygen concentration in the exhaust gas, which is a detected exhaust gas component. When the second predetermined condition is satisfied, λ feedback correction control of the fuel injection amount is performed.
In the feedback correction control of the fuel injection amount that is performed when the first predetermined condition is satisfied, the first predetermined condition includes not only a uniquely determined operation state but also a different correction state depending on a combination of several conditions. ing. The normal feedback correction control is added with various corrections such as electric system and air conditioner load, warm-up control.
Regarding the λ feedback correction control of the fuel injection amount performed under the second predetermined condition, the λ feedback correction control is a control excluding various correction coefficients so as to be substantially only the learning correction value. The second predetermined condition is when the λ feedback condition is established (ON), and is a state where there are no various additional correction conditions such as the first predetermined condition.
Here, the λ feedback correction control performed when the second predetermined condition (steady operation determination condition) is established means an excess ratio of the air-fuel mixture supplied to the engine 1 (ratio of the air-fuel ratio of the air-fuel mixture to the stoichiometric air-fuel ratio). ) The fuel injection amount is controlled so that λ becomes λ = 1. Unlike the normal feedback correction control that is performed when the first predetermined condition is satisfied, the λ feedback correction control does not immediately determine an accurate air-fuel ratio in steady operation, and various corrections are required in actual fuel injection control. Therefore, it is necessary to perform the correction after selecting a correction state selected from those correction controls, that is, during the λ feedback correction control in which excessive correction is not performed.

A fuel injection control device 43 that performs normal feedback correction control and λ feedback correction control of the theoretical air-fuel ratio with respect to the fuel injection amount of the engine 1 that uses gasoline and ethanol as fuel, determines the properties of the fuel supplied to the engine 1. A fuel property identifying means 50 for identifying is provided in the fuel control unit 44. The fuel property identification means 50 is provided with a characteristic line map 51 (see FIG. 3) showing the characteristics of the theoretical air-fuel ratio and the ethanol mixture ratio of the fuel, and the fuel is determined from the detected intake air amount and the calculated fuel injection amount. Air-fuel ratio calculating means 52 for calculating the air-fuel ratio is provided. The characteristic line map 51 is stored in the storage unit 49.
The fuel injection control device 43 calculates the air-fuel ratio of the current fuel by the air-fuel ratio calculating means 52 while the fuel property identifying means 50 is performing the λ feedback correction control when the second predetermined condition is satisfied (FIG. 1). 107), the step of calculating the ethanol mixture ratio of the current fuel by comparing the obtained air fuel ratio with the characteristic line map 51 (108 in FIG. 1), and the storage means 49 for storing the ethanol mixture ratio of the current fuel. (108 in FIG. 1), and thereafter, when the first predetermined condition is satisfied, feedback correction control of the fuel injection amount is performed using the ethanol mixing ratio of the current fuel.
The fuel property identification means 50 is provided with the storage means 49 capable of registering in advance the specific gravity of fuel or the physical property value of fuel containing C (carbon) / H (hydrogen), and the characteristic line map 51 of the fuel registered in the storage means 49 is provided. Use it after correcting it according to its physical properties.
The fuel property identification means 50 calculates the current fuel air-fuel ratio or mixes ethanol after the refueling determination condition is satisfied and when the λ feedback correction control is being performed and the fluctuation value of the vehicle speed is smaller than a certain value. Perform a series of steps up to storing the ratio.

Next, the operation will be described.
This fuel property identifying means 50 calculates the ethanol mixing ratio in an extremely general λ feedback correction controlled engine 1 without requiring any additional device.
The air / fuel ratio is
Intake air weight / injected fuel weight = (theoretical) air-fuel ratio (1)
It is calculated by the following formula. However, the intake air amount is always obtained as a weight by the air flow sensor 46 and is taken into the fuel control unit 44. The fuel injection amount is always calculated by the calculation means 48 in the fuel control unit 44 as the injection amount (volume) from the opening time of the fuel injection valve 39. Therefore, if the specific gravity of gasoline (or ethanol mixed gasoline) is fixed as a fixed value (for example, ρ = 0.76), the fuel injection weight can be constantly monitored. Basically, the specific gravity of gasoline is about ρ = 0.74 to 0.76, and the specific gravity of ethanol is about ρ = 0.789, both of which do not change greatly.
In the engine 1 that performs the λ feedback correction control, after the engine 1 is warmed up, the operation is performed with the air excess ratio λ = 1 in a stable state during steady operation. At this time, the air-fuel ratio is a mean is operated at the stoichiometric air-fuel ratio at the fuel, from the equation (1), it is possible to obtain the absolute value A / F _F the theoretical air-fuel ratio of the fuel used.
Here, if the gasoline does not contain ethanol, that is, the theoretical air-fuel ratio value of E ₀ is A / F ₀ and the theoretical air-fuel ratio at E ₁₀₀ is A / F ₁₀₀ , A / F ₁₀₀ = 8.96. From the lines of A / F ₀ and A / F ₁₀₀ , the relationship between the stoichiometric air-fuel ratio and the ethanol mixing ratio can be derived as shown in FIG.
In the fuel property identification means 50, to measure the air-fuel ratio A / F _F during steady operation of lambda = 1, with the characteristic line map 51 of ethanol mixing ratio of the stoichiometric air-natural ratio and fuel shown from that value in FIG. 3 Thus, the ethanol mixing ratio of the fuel is obtained.

The process of calculating the fuel ethanol mixture ratio will be described with reference to FIG.
As shown in FIG. 1, the fuel injection control device 43 starts the process of calculating the ethanol mixing ratio of the fuel (101) as shown in FIG. 1 (101). ₀ is registered (set) (102). Data E ₀ includes specific gravity ρ, theoretical air-fuel ratio A / F ₀ , C (carbon) / H (hydrogen), fuel injection time TAU, and intake air amount MAF. Specific gravity ρ, theoretical air-fuel ratio A / F ₀ , and C (carbon) / H (hydrogen) are fixed values.
Next, it is determined whether the refueling determination condition is satisfied (103). When this determination (103) is YES, the control of (104) to (109) is performed. If this determination (103) is NO, the process proceeds to another control (110). The determination (103) of the refueling determination condition is performed in the engine 1 that is performing the refueling determination, and is not performed when the refueling determination is not performed.
If the determination (103) is YES, it is determined whether the λ feedback condition as the second predetermined condition is ON (established) (104). The λ feedback condition includes that the engine 1 is warmed up.
If this determination (104) is NO, this determination (104) is repeated. If this determination (104) is YES, it is determined whether the λ feedback correction control is being performed (105). If this determination (105) is NO, the process returns to the determination (104). If this determination (105) is YES, it is determined whether the steady operation determination condition is satisfied (106). The steady operation determination condition is when the vehicle speed fluctuation value ΔV is smaller than a certain value (ΔV ≦ constant value).
If this determination (106) is NO, the process returns to the determination (104). If this determination (106) is YES, the engine 1 is currently operating at a stoichiometric air-fuel ratio based on fuel, and is detected by the calculated fuel injection amount (for example, a signal from the fuel injection valve 39) and the air flow meter 46. calculating an air-fuel ratio a / F _F current fuel from the intake air amount (107), ethanol mixing ratio of the current fuel compared empty Shikahi a / F _F current fuel obtained with a characteristic line map 51 The calculated ethanol mixture ratio of the present fuel is stored in the storage means 49 (108), and the process is terminated (109).
When calculating the current current ethanol mixing ratio of the fuel by comparing the empty Shikahi A / F _F characteristic line map 51 of a fuel (108), the physical properties of the gasoline for reference registered in (102) The characteristic line map 51 is corrected by the value data E ₀ and used.

As shown in FIG. 2, the fuel injection control device 43 uses the current fuel ethanol mixture ratio stored in the storage means 49 to feedback the fuel injection amount when the first predetermined condition is satisfied. Perform correction control.
In FIG. 2, when control is started (201), detection values (intake air temperature, intake air amount, fuel injection amount, etc.) of various sensors are input (202), and the fuel injection amount is calculated (203). In the calculation (203) of the fuel injection amount, the fuel injection amount is calculated using the ethanol mixing ratio of the current fuel stored in the storage means 49. After the calculation, the fuel injection valve 39 is controlled so that the obtained fuel injection amount is obtained, and the control is finished (204).

As described above, the fuel property identification unit 50 of the fuel injection control device 43 performs the determination of the fuel property during the execution of the λ feedback correction control targeting the theoretical air-fuel ratio, thereby providing a dedicated alcohol concentration detection unit. Even if it is not provided, it is possible to grasp the fuel properties, particularly the ethanol mixing ratio. Then, optimal fuel injection control can be performed by performing feedback correction control of the fuel injection amount in accordance with the grasped ethanol mixture ratio.
In addition, since the fuel property identification means 50 of the fuel injection control device 44 uses the characteristic line map 51, even if the fuel property changes suddenly due to refueling or the like, especially if the ethanol mixing ratio changes greatly, Updates to changes in fuel properties can proceed quickly. By entering the operating state in which λ feedback correction control is performed at a relatively early stage after refueling, the amount of exhaust gas harmful components that have deteriorated during traveling can be suppressed.
The fuel property identification means 50 of the fuel injection control device 44 is provided with a storage means 49 that can pre-register fuel property values including the specific gravity of fuel or C / H, and the fuel in which the characteristic line map 51 is registered in the storage means 49. By correcting and using the physical property value, it is possible to make more accurate determination by storing data with sufficient accuracy in advance.
Further, the fuel property identification means 50 of the fuel injection control device 44 is performing the λ feedback correction control after the fuel supply determination condition is satisfied (103: YES), and the fluctuation value of the vehicle speed is smaller than a certain value. In the case (106: YES), by performing a series of steps (107, 108) from the calculation of the air-fuel ratio of the current fuel to the storage of the ethanol mixture ratio, fuel with greatly different properties is supplied or slightly different properties Even if the fuel is refueled, the fuel injection control can be performed by accurately managing the ethanol mixing ratio, and if the fuel property determination is limited after refueling, the load on the computing capacity of the control device will also be increased. Can be suppressed.
In this example, the specific gravity ρ at E ₀ of gasoline not containing ethanol was fixed as 0.76, but this is the C / H ratio of fuel (which affects the stoichiometric air-fuel ratio of E ₀ ). In addition, there are some changes depending on the country and season. Therefore, in order to obtain a more accurate ethanol mixing ratio, an A / F ₀ value taking these values into consideration can be input as an initial value at the time of factory shipment or at the time of inspection by a dealer.
Here, the value of gasoline that matches the market (the value of the base gas when ethanol gasoline is distributed) is input. Thereby, a more accurate ethanol mixing ratio of the fuel can be obtained.

  The present invention calculates and stores the ethanol mixing ratio of the current fuel by comparing the air fuel ratio of the current fuel with the characteristic line map during the λ feedback correction control, and uses the ethanol mixing ratio of the current fuel. This is to perform feedback correction control of the fuel injection amount, and can be applied to control of an engine using two types of fuel.

1 engine 6 combustion chamber 7 an intake port 8 an exhaust port 18 intake path 24 exhaust path 39 fuel injection valve 45 intake air temperature sensor 46 Airflow sensor 47 O ₂ sensor 48 calculating means 49 storage means 50 fuel property identification means 51 characteristic line map 52 air Calculation means

Claims (3)

An intake air amount detection means, a fuel injection amount calculation means, and an exhaust gas component detection means;
Based on the detected exhaust gas component, fuel that performs feedback correction control of the fuel injection amount when the first predetermined condition is satisfied, and performs λ feedback correction control of the fuel injection amount when another second predetermined condition is satisfied In the fuel property identifying means of the injection control device,
A characteristic line map showing the characteristics of the theoretical air-fuel ratio and the ethanol mixing ratio of fuel is provided.
An air-fuel ratio calculating means for calculating the fuel air-fuel ratio from the detected intake air amount and the calculated fuel injection amount;
During the execution of λ feedback correction control when the second predetermined condition is satisfied by the fuel property identification means,
Calculating an air-fuel ratio of the current fuel by the air-fuel ratio calculating means;
Comparing the obtained fuel-to-air ratio with the characteristic line map to calculate a current fuel ethanol mixing ratio;
And storing the current fuel ethanol mixing ratio,
After that, when the first predetermined condition is satisfied, the fuel property identifying means of the fuel injection control device performs feedback correction control of the fuel injection amount using the ethanol mixture ratio of the current fuel. A storage means for pre-registering the physical property value of the fuel including the specific gravity or C / H of the fuel is provided,
2. The fuel property identifying means of the fuel injection control apparatus according to claim 1, wherein the characteristic line map is used after being corrected by a physical property value of fuel registered in the storage means.   After the refueling determination condition is satisfied and when the λ feedback correction control is being performed and the fluctuation value of the vehicle speed is smaller than a certain value, a series of processes from the calculation of the current fuel air-fuel ratio to the storage of the ethanol mixture ratio are performed. The fuel property identifying means of the fuel injection control device according to claim 1, wherein the step is performed.

Images