CN104975968A - Fuel injection dose control device for engine - Google Patents

Abstract

The present invention provides a fuel injection amount control device for an engine, which uses an α-N method, estimates an intake air amount to be introduced into a combustion chamber with higher accuracy, and appropriately controls fuel injection based on the estimated intake air amount. quantity. An electronic control unit ECU (20) estimates an intake air amount Ga based on a throttle opening TA and an engine speed NE, and controls an injector (4) based on a fuel injection amount TAU calculated from Ga. When the engine is running, the ECU (20) performs the following operations: refer to the ISC flow rate characteristic data to obtain the current ISC flow rate relative to the current ISC control amount, and refer to the first intake air amount map to obtain the relationship between the ISC flow rate when it becomes the minimum value and TA and The first intake air amount GaA corresponding to NE, and the second intake air amount GaB corresponding to TA and NE when the ISC flow rate reaches the maximum value are obtained by referring to the second intake air amount map, based on the current ISC flow rate and the maximum ISC flow rate The relationship between the value and the minimum value is interpolated between GaA and GaB to estimate the current Ga.

Description

Engine fuel injection quantity control device

technical field

The present invention relates to a fuel injection amount control device for controlling the fuel injection amount supplied to an engine. Specifically, it relates to a system configured to estimate the amount of intake air drawn into the engine based on the respectively detected throttle opening and engine speed without using an intake air amount detection means, and to control fuel injection based on the estimated intake air amount. The fuel injection quantity control device of the engine.

Background technique

Conventionally, in this technique, the basic fuel injection amount is usually calculated using the intake air amount sucked into the engine and the engine speed as parameters, and the basic fuel injection amount is corrected by various correction items to calculate the final fuel injection amount . Here, in order to obtain the intake air amount, there is known a so-called α-N method in which the opening degrees of the throttle valves provided in the intake passage of the engine are individually detected without using an intake air amount detection device such as an air flow meter. (throttle valve opening) and engine speed, and the intake air amount is estimated based on these throttle opening and engine speed. By adopting the α-N method, the engine system can be simplified and advantages such as cost reduction can be obtained. As the fuel injection amount control using such an α-N method, techniques described in the following Patent Documents 1 to 3 are known, for example. Here, it is described in Patent Document 1 that in the α-N system, the throttle valve opening is an important factor for determining the intake air amount, and there is a difference between the estimated intake air amount and the actual intake air amount. When there is a difference between them, the air-fuel ratio control of the engine deteriorates. In addition, the engine described in Patent Document 2 is provided with a bypass passage that bypasses the throttle valve, and an ISC valve that opens and closes to control the idle speed of the engine is provided on the bypass passage.

In addition, in the operation control device for an internal combustion engine described in Patent Document 3, the amount of air passing through the throttle valve (throttle flow rate) is estimated from the throttle opening and the engine speed, and is estimated from the value of the current flowing through the solenoid coil of the ISC valve. The amount of air flowing in the bypass passage (ISC flow rate) is estimated by adding the throttle flow rate and the ISC flow rate to estimate the intake air amount introduced into the combustion chamber of the engine, and the fuel injection amount is calculated from the intake air amount .

On the other hand, in the intake passage of the engine, deposits may adhere to the inner wall to narrow the flow path area, and deposits may also adhere to the throttle valve and ISC valve. In addition, it is well known that the deposition amount increases over time. If such deposits adhere to the air intake system, it will become an obstacle to air flow, so it is difficult to maintain the original air intake of the product as it is. Therefore, Patent Document 4 below proposes an idling rotation control device capable of accurately performing engine air intake control during idling in consideration of the deposition state of deposits on the throttle valve side and the ISC valve side. In this device, an electronic control unit (ECU) learns a state of deposits attached to an intake system equipped with a throttle valve and an ISC valve and performs intake control. Specifically, the ECU performs learning by distinguishing a first learning area for checking the amount of deposits on the throttle valve side and a second learning area for checking the amount of deposits on the ISC valve side. In this way, the characteristic of the loss flow rate (loss characteristic) which is the difference between the initial intake air amount of the product and the actual intake air amount is confirmed, and the loss characteristic is utilized for intake control during idling operation. In this device, an air flow meter is used to detect the initial intake air volume of the product and the subsequent real air intake volume.

prior art literature

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 5-10170

Patent Document 2: Japanese Patent Laid-Open No. 2001-140680

Patent Document 3: Japanese Patent Laid-Open No. 63-183247

Patent Document 4: Japanese Patent Laid-Open No. 2007-321661

Contents of the invention

The problem to be solved by the invention

In addition, in the operation control device described in Patent Document 3, even if the current value flowing through the electromagnetic coil of the ISC valve is constant, that is, the opening degree of the ISC valve is constant, the throttle valve opening may change due to a change in the opening degree of the throttle valve. The downstream pressure changes, causing the ISC flow to change. Also, even if the opening degree of the throttle valve is constant, the pressure downstream of the throttle valve may change due to changes in the opening degree of the ISC valve, thereby changing the amount of air flowing through the throttle valve. However, in this operation control device, the throttle flow rate estimated from the throttle opening and the engine speed is simply added to the ISC flow rate estimated from the current value flowing in the electromagnetic coil of the ISC valve to calculate the flow rate introduced into the ISC valve. The amount of intake air in the combustion chamber, therefore, does not take into account changes in the ISC flow rate or throttle flow rate due to changes in the opening of the throttle valve or ISC valve. As a result, it may not be possible to accurately estimate the amount of intake air introduced into the combustion chamber. The amount of intake air in the engine cannot accurately control the amount of injected fuel being supplied to the engine.

On the other hand, it is conceivable to apply the technology of learning the deposition state and controlling the intake air to the engine using the α-N system. However, the device of Patent Document 4 configured to detect the intake air amount using an air flow meter cannot be applied as it is to the α-N system that does not use intake air amount detection means such as an air flow meter. Therefore, it is also desirable to estimate the intake air amount while learning the state of deposit attachment to the intake system in which the throttle valve and the ISC valve are disposed, and to reflect the intake air amount in the fuel injection amount control for an engine employing the α-N system.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel injection amount control device for an engine that employs an α-N system having an intake system including a throttle valve and an ISC valve, The amount of intake air introduced into the combustion chamber can be estimated with higher accuracy, and the fuel injection amount can be appropriately controlled based on the estimated intake air amount. Furthermore, in addition to the above objects, another object of the present invention is to provide a fuel injection amount control device for an engine capable of estimating the state of adhesion of deposits to an intake system including a throttle valve and an ISC valve. The more accurate intake air amount, and the fuel injection amount is more appropriately controlled based on the estimated intake air amount.

solutions to problems

In order to achieve the above object, the invention described in technical solution 1 is a fuel injection amount control device for an engine, which includes: an air intake passage, which is used to introduce intake air into the combustion chamber of the engine; a throttle valve, which is used to adjust The intake air flow in the intake passage; the bypass passage, which is arranged on the intake passage by bypassing the throttle valve; the ISC valve, which is used to regulate the intake air flow in the bypass passage; the fuel injection part, which is used to The engine injects fuel; the opening detection part is used to detect the opening degree of the throttle valve; the rotational speed detection part is used to detect the rotational speed of the engine; and the control part is based on the detected opening degree of the throttle valve and the detected The engine speed estimates the amount of intake air introduced into the combustion chamber, calculates the fuel injection amount based on the estimated intake air amount, and controls the fuel injection member based on the calculated fuel injection amount. The gist of the fuel injection amount control device for the engine That is, the control unit has: ISC flow rate characteristic data, which presets the relationship between the ISC flow rate flowing in the bypass passage when the throttle valve is fully closed and the opening degree of the ISC valve; the maximum and minimum values of the ISC flow rate , which is preset; the first intake air amount map, which presets the first intake air amount introduced into the combustion chamber, the opening degree of the throttle valve and the engine's The relationship between the rotational speed; and the second intake air amount map, which presets the relationship between the second intake air amount introduced into the combustion chamber, the opening degree of the throttle valve, and the rotational speed of the engine when the ISC flow rate becomes the maximum value. The control unit performs the following operations when the engine is running: refer to the ISC flow characteristic data to obtain the current ISC flow relative to the current ISC valve opening degree, and refer to the first intake air amount map to obtain the current ISC flow rate. When the ISC flow rate becomes the minimum value, the first intake air amount corresponding to the opening degree of the throttle valve and the engine speed is referred to the second intake air amount map, thereby obtaining the throttle rate when the ISC flow rate becomes the maximum value. The opening degree of the gate valve and the second intake air volume corresponding to the engine speed are compared between the first intake air volume and the second intake air volume according to the relationship between the current ISC flow rate and the maximum and minimum values of the ISC flow rate. Interpolation, from which the current intake air volume is estimated.

According to the structure of the above invention, the amount of intake air introduced into the combustion chamber, that is, the amount of air passing through the throttle valve and the amount of air passing through the ISC can be estimated from the engine speed detected at this time, the opening degree of the throttle valve, and the current ISC flow rate. The total air volume of the valve air volume. Here, by referring to the first intake air amount map that determines the first intake air amount when the ISC flow rate becomes the minimum value and the second intake air amount map that determines the second intake air amount when the ISC flow rate becomes the maximum value, the The first air intake volume and the second air intake volume are displayed. Furthermore, by interpolating between the first intake air amount and the second intake air amount based on the relationship between the current ISC flow rate and the maximum and minimum values of the ISC flow rate, the current progress corresponding to the current ISC flow rate is estimated. capacity. Since the relationship between the total air volume of the air volume passing through the throttle valve and the air volume passing through the ISC valve is set in advance in the first intake air volume map and the second intake air volume map, it is possible to obtain a more accurate calculation according to the ISC flow rate. Accurate 1st intake volume and 2nd intake volume. Therefore, the amount of intake air introduced into the combustion chamber can be estimated by considering the influence of the opening degree of the ISC valve on the amount of air passing through the throttle valve and the influence of the opening degree of the throttle valve on the amount of air passing through the ISC valve.

In order to achieve the above object, according to the invention described in technical solution 1, the gist of the invention described in technical solution 2 is that the control unit performs the following operations: when the engine is idling, in order to adjust the rotational speed of the engine to a predetermined idling rotational speed Feedback control is performed on the ISC valve, and the ISC control amount of the ISC valve at this time is learned as the ISC learning value. When the engine is running, the ISC flow rate corresponding to the current ISC learning value is obtained by referring to the ISC flow rate characteristic data. Learning value, correct the current ISC flow rate according to the current ISC flow rate learning value, and then calculate the corrected ISC flow rate. According to the relationship between the corrected ISC flow rate and the maximum and minimum values of the ISC flow rate, the first intake air volume and The current intake air amount is estimated by interpolating between the second intake air amounts.

According to the configuration of the invention, in addition to the effect of the invention described in Claim 1, the corrected ISC flow rate is calculated by correcting the current ISC flow rate based on the current ISC flow rate learning value reflecting the annual change and the like. Furthermore, the current intake air amount is estimated by interpolating between the first intake air amount and the second intake air amount based on the relationship between the corrected ISC flow rate and the maximum and minimum values of the ISC flow rate. Thus, it is possible to estimate the intake air amount that has reflected the yearly variation caused by deposit adhesion and the like in the intake system including the throttle valve and the ISC valve.

In order to achieve the object, according to the invention described in claim 2, the gist of the invention described in claim 3 is that when the obtained ISC flow rate learning value is a value within a predetermined range including a predetermined reference value , and correct the ISC flow learning value to a predetermined reference value.

According to the structure of the invention, in addition to the effect of the invention described in claim 2, even if the obtained ISC flow rate learning value deviates within a predetermined range including a predetermined reference value, the ISC flow rate learning value can be corrected. Since it is a predetermined reference value, it is possible to eliminate deviations and minute fluctuations in the learned value of the ISC flow rate.

The effect of the invention

According to the invention described in claim 1, in an engine employing an α-N system having an intake system including a throttle valve and an ISC valve, the amount of intake air introduced into the combustion chamber can be estimated with higher accuracy, and the This estimated intake air amount appropriately controls the fuel injection amount.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, it is possible to estimate a more accurate intake air amount that has reflected the state of deposition of deposits attached to the intake system including the throttle valve and the ISC valve. , the fuel injection amount can be more appropriately controlled based on the estimated intake air amount.

According to the invention described in claim 3, in addition to the effects of the invention described in claim 2, when the engine is new, the intake air amount can be estimated stably, and the intake air amount can be controlled more precisely based on the intake air amount. amount of fuel injected.

Description of drawings

FIG. 1 relates to the first embodiment and is a schematic configuration diagram showing an engine system.

2 relates to the first embodiment and is a flowchart showing an intake air amount calculation routine for estimating and calculating the intake air amount.

FIG. 3 is a graph showing ISC flow rate characteristics related to the first embodiment.

FIG. 4 relates to the first embodiment and is a conceptual diagram showing a first intake air amount map.

FIG. 5 is a conceptual diagram showing a second intake air amount map related to the first embodiment.

6 relates to the first embodiment and is a flowchart showing a fuel injection amount control routine.

7 relates to the second embodiment and is a graph showing variations in ISC flow rate characteristics at the initial stage of the product.

Fig. 8 relates to the second embodiment and is a graph showing the annual change of the ISC flow rate characteristic.

9 relates to the second embodiment and is a graph showing variations in the initial intake air amount characteristics of the product.

FIG. 10 relates to the second embodiment and is a graph showing the temporal change of the intake air amount characteristic.

Fig. 11 relates to the second embodiment and is a flowchart showing an intake air amount calculation routine.

FIG. 12 is a graph showing ISC flow rate characteristics related to the second embodiment.

Fig. 13 relates to the second embodiment and is a graph showing changes in the air-fuel ratio learned value with respect to the learned region.

Fig. 14 relates to the third embodiment and is a flowchart showing an intake air amount calculation routine.

FIG. 15 relates to the third embodiment and is a correction map referred to for obtaining an ISC learning correction value for an ISC flow rate learning value.

Detailed ways

<First Embodiment>

Hereinafter, a first embodiment embodying a fuel injection amount control device for an engine according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an engine system according to the present embodiment with a schematic configuration diagram. An engine system mounted on a two-wheeled vehicle includes a fuel tank 1 for storing fuel. A fuel pump 2 built in the fuel tank 1 ejects fuel stored in the tank 1 . The reciprocating single-cylinder engine 3 is provided with an injector 4 corresponding to an example of the fuel injection member of the present invention. Fuel injected from fuel pump 2 is supplied to injector 4 through fuel passage 5 . When the injector 4 is opened, the supplied fuel is injected into the intake passage 6 . Air is sucked into the intake passage 6 from the outside via the air cleaner 7 . The air sucked into the intake passage 6 and the fuel injected from the injector 4 form a combustible mixture, which is sucked into the combustion chamber 8 .

A throttle valve 9 operated by a predetermined acceleration device (not shown) is provided on the intake passage 6 . By opening and closing the throttle valve 9 , the amount of air sucked from the intake passage 6 into the combustion chamber 8 (intake air amount) is adjusted. A bypass passage 10 bypassing the throttle valve 9 is provided on the intake passage 6 . An idle control valve (ISC valve) 11 is provided in the bypass passage 10 . The ISC valve 11 operates to adjust the idling speed of the engine 3 during idling in which the throttle valve 9 is substantially fully closed.

A spark plug 12 provided on the combustion chamber 8 receives an ignition signal output from an ignition coil 13 to perform an ignition operation. The two members 12 , 13 constitute an ignition device for igniting the combustible air-fuel mixture supplied to the combustion chamber 8 . The combustible air-fuel mixture sucked into the combustion chamber 8 explodes and burns by the ignition action of the spark plug 12 . Combusted exhaust gas is discharged from the combustion chamber 8 to the outside through the exhaust passage 14 . A three-way catalyst 15 for purifying exhaust gas is provided on the exhaust passage 14 . As the combustible air-fuel mixture in the combustion chamber 8 is combusted, the piston 16 moves and the crankshaft 17 rotates, so that driving force for running the vehicle can be obtained.

The vehicle is provided with an ignition switch 18 that is operated to start the engine 3 . An electronic control unit (ECU) 20 for performing various controls of the engine 3 is provided on the vehicle. A battery 19 serving as a power source for the vehicle is connected to the ECU 20 through an ignition switch 18 . By turning on the ignition switch 18 , electric power is supplied from the battery 19 to the ECU 20 .

Various sensors 22 , 23 , 24 , and 25 provided on the engine 3 are used to detect various operating parameters related to the operating state of the engine 3 , and are respectively connected to the ECU 20 . That is, the water temperature sensor 22 provided on the engine 3 detects the temperature (cooling water temperature) THW of the cooling water flowing inside the engine 3, and outputs an electric signal corresponding to the detected value. A rotational speed sensor 23 provided on the engine 3 detects the rotational speed (engine rotational speed) NE of the crankshaft 17 and outputs an electric signal corresponding to the detected value. The rotational speed sensor 23 is equivalent to an example of the rotation detection means of this invention. The oxygen sensor 24 provided in the exhaust passage 14 detects the oxygen concentration (output voltage) Ox in the exhaust gas discharged into the exhaust passage 14, and outputs an electric signal corresponding to the detected value. This oxygen sensor 24 is used to obtain the air-fuel ratio A/F of the combustible air-fuel mixture supplied to the combustion chamber 8 of the engine 3 . A throttle sensor 25 provided corresponding to the throttle valve 9 detects the opening degree (throttle opening) TA of the throttle valve 9 and outputs an electric signal corresponding to the detected value. The throttle sensor 25 corresponds to an example of the opening detection means of the present invention.

In the present embodiment, the ECU 20 inputs various signals output from the aforementioned various sensors 22 to 25 . The ECU 20 controls the ISC valve 11 , the fuel pump 2 , the injector 4 , the ignition coil 13 , and the like to execute ISC control, fuel injection amount control, ignition timing control, and the like based on these input signals. In the present embodiment, ECU 20 corresponds to an example of the control means of the present invention.

As is well known, the ECU 20 includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. The ECU 20 constitutes a logical operation circuit in which the CPU, ROM, RAM, and backup RAM are connected to an external input circuit, an external output circuit, and the like via a bus. The ROM stores predetermined control programs related to various controls of the engine 3 in advance. The RAM temporarily stores the calculation results of the CPU. Backup RAM holds pre-stored data. The CPU executes the aforementioned various controls and the like in accordance with a predetermined control program based on the detection signals of the various sensors 22 to 25 input through the input circuit.

Here, the ignition timing control refers to controlling the ignition coil 13 in order to control the ignition timing of the spark plug 12 according to the operating state of the engine 3 . The ISC control refers to performing feedback control on the ISC valve 11 when the throttle valve 9 is fully closed so that the engine speed NE becomes a predetermined idle speed.

The fuel injection amount control refers to controlling the fuel injection amount supplied to the engine 3 by controlling the injector 4 according to the operating state of the engine 3 . In the present embodiment, the "α-N method" is adopted, that is, the intake air amount detection component such as an air flow meter is not used, but the throttle opening TA detected by the throttle sensor 25 and the throttle opening TA detected by the rotational speed sensor 23 are used. The intake air amount Ga drawn into the combustion chamber 8 is estimated at the engine speed NE. Then, the fuel injection amount TAU is calculated based on the estimated intake air amount Ga, and the injector 4 is controlled based on the calculated fuel injection amount TAU to control the injection amount supplied to the engine 3 .

Here, even if the opening degree of the ISC valve 11 is constant, the downstream pressure of the throttle valve 9 may change due to a change in the opening degree of the throttle valve 9 , thereby changing the ISC flow rate. In addition, even if the opening degree of the throttle valve 9 is constant, the opening degree of the ISC valve 11 may change to cause the downstream pressure of the throttle valve 9 to change, thereby causing the throttle flow rate to change. As a result, the amount of intake air introduced into the combustion chamber 8 cannot be accurately obtained, and the fuel injection amount supplied to the combustion chamber 8 cannot be accurately controlled.

Therefore, in the present embodiment, in an engine system employing the α-N system including an intake system including a throttle valve and an ISC valve, the amount of intake air introduced into the combustion chamber 8 is estimated with higher accuracy, and based on this The estimated intake air amount appropriately controls the fuel injection amount. For this reason, the ECU 20 executes fuel injection amount control as follows.

FIG. 2 shows an intake air amount calculation routine for estimating and calculating the total intake air amount introduced into the combustion chamber 8 , that is, the intake air amount Ga, using a flowchart. ECU 20 periodically executes the routine shown in FIG. 2 every predetermined period. Here, "periodically performed every predetermined period" means that the measurement by the timer is carried out periodically every predetermined time, or that every predetermined crank angle (eg, Exhaust top dead center (TDC) of the engine is executed periodically.

When the process shifts to this routine, the ECU 20 reads the engine speed NE from the detection value of the speed sensor 23 in step 100 . In addition, in step 110 , the ECU 20 reads the throttle opening TA from the detection value of the throttle sensor 25 .

Next, in step 120 , the ECU 20 obtains the ISC flow rate Y1 relative to the current ISC control amount y1 by referring to the ISC flow rate characteristic shown in a graph in FIG. 3 . In the graph of FIG. 3 , the relationship between the ISC flow rate (the amount of air flowing through the bypass passage 10 ) and the ISC control amount (command value sent to the ISC valve 11 ) is confirmed and determined in advance. In this ISC flow rate characteristic, the ISC flow rate changes gradually in the low-middle opening range where the ISC control amount is small to medium, and changes rapidly in the high opening range where the ISC control amount is large.

Next, in step 130 , the ECU 20 calculates the first intake air amount GaA when the ISC flow rate is the minimum value ISCmin from the read engine speed NE and throttle opening TA by referring to the first intake air amount map. FIG. 4 shows a conceptual diagram of the first intake air amount map. In this map, the first intake air amount GaA when the ISC flow rate is the minimum value ISCmin is determined from the relationship between the engine speed NE and the throttle opening TA. Here, the ISC control amount when the ISC flow rate is the minimum value ISCmin is the minimum value α (see FIG. 3 ).

Next, in step 140 , the ECU 20 calculates the second intake air amount GaB when the ISC flow rate reaches the maximum value ISCmax from the read engine speed NE and throttle opening TA by referring to the second intake air amount map. FIG. 5 shows a conceptual diagram of the second intake air amount map. In this map, the second intake air amount GaB when the ISC flow rate is the maximum value ISCmax is determined from the relationship between the engine speed NE and the throttle opening TA. Here, the ISC control amount when the ISC flow rate is the maximum value ISCmax is the maximum value β (see FIG. 3 ).

Then, in step 150 , the ECU 20 returns the process to step 100 after calculating the intake air amount Ga. The ECU 20 can obtain the intake air amount Ga from the following calculation formula (1).

Ga←GaA+(GaB－GaA)*(Y1－ISCmin)/(ISCmax－ISCmin)...(1)

That is, in the aforementioned calculation formula (1), (GaB−GaA) means the second intake air amount GaB and The difference between the first intake air amount GaA (maximum and minimum intake air amount difference) estimated from the throttle valve opening TA and the engine speed NE when the ISC flow rate becomes the minimum value ISCmin. (Y1−ISCmin) means the difference between the current ISC flow rate Y1 and the minimum value ISCmin of the ISC flow rate (minimum side ISC flow rate difference). In addition, (ISCmax−ISCmin) means the difference between the maximum value ISCmax and the minimum value ISCmin of the ISC flow rate (the difference between the maximum and minimum ISC flow rates). Therefore, in calculation formula (1), the current intake air amount is estimated by interpolating between the first intake air amount GaA and the second intake air amount GaB based on the ratio of the minimum side ISC flow rate difference to the maximum and minimum ISC flow rate difference The amount of Ga.

Next, a fuel injection amount control routine executed using the intake air amount Ga estimated as described above as one of the parameters is shown in a flowchart in FIG. 6 . The ECU 20 periodically executes the routine shown in FIG. 6 every predetermined period.

When the process shifts to this routine, the ECU 20 reads the estimated intake air amount Ga in step 300 .

Next, in step 310, the ECU 20 reads the target air-fuel ratio Taf. For example, the ECU 20 can separately calculate the target air-fuel ratio Taf according to the operating state of the engine 3 .

Next, in step 320, the ECU 20 reads the fuel specific gravity γ. This fuel specific gravity γ is a value set in advance and stored in the memory of ECU 20 .

Next, in step 330, the ECU 20 reads the injector flow rate characteristic Cinj. This injector flow rate characteristic Cinj is also a value set in advance and stored in the memory of the ECU 20 .

Next, in step 340 , the ECU 20 calculates the basic fuel injection amount bTAU based on the read parameters Ga, Taf, γ, and Cinj in accordance with the following calculation formula (2).

bTAU←Ga/Taf＊γ＊Cinj...(2)

Next, in step 350, the ECU 20 calculates a fuel injection amount correction coefficient Cf. For example, the ECU 20 can separately calculate the fuel injection amount correction coefficient Cf from the cooling water temperature THW and the oxygen concentration Ox.

Next, in step 360 , the ECU 20 calculates the fuel injection amount TAU according to the following calculation formula (3) based on the various parameters bTAU and Cf calculated above.

TAU←bTAU＊Cf...(3)

Then, in step 370, the ECU 20 injects fuel from the injector 4 by controlling the injector 4 based on the calculated fuel injection amount TAU. Thereafter, ECU 20 returns the process to step 300 .

According to the fuel injection amount control device for the engine of the present embodiment described above, the fuel injected into the combustion chamber 8 is estimated based on the engine speed NE and the throttle opening TA detected at this time, and the current (at this time) ISC flow rate Y1. The intake air amount Ga, that is, the total air amount of the air amount passing through the throttle valve 9 (throttle flow rate) and the air amount passing through the ISC valve 11 (ISC flow rate). Here, by referring to the first intake air map that determines the first intake air amount GaA when the ISC flow rate is the minimum value ISCmin and the second intake air map that determines the second intake air amount GaB when the ISC flow rate is the maximum value ISCmax The first intake air amount GaA and the second intake air amount GaB can be obtained from the amount map. Furthermore, by interpolating between the first intake air amount GaA and the second intake air amount GaB based on the relationship between the current ISC flow rate and the maximum value ISCmax and the minimum value ISCmin of the ISC flow rate, it is possible to estimate the current ISC flow rate. Corresponding to the current intake air amount Ga. Since the first intake air amount map and the second intake air amount map preset the relationship between the total air amount of the throttle valve flow and the ISC flow corresponding to the engine speed NE and the throttle opening TA, it can be compared with the ISC flow Correspondingly, more accurate first intake air amount GaA and second intake air amount GaB are obtained. Therefore, the intake air amount Ga introduced into the combustion chamber 8 is estimated by considering the influence of the opening degree of the ISC valve 11 on the throttle flow rate and the influence of the opening degree of the throttle valve 9 on the ISC flow rate, respectively. Therefore, in an engine employing the α-N system including an intake system including the throttle valve 9 and the ISC valve 11 , the intake air amount Ga introduced into the combustion chamber 8 can be estimated with higher accuracy. As a result, the final fuel injection amount TAU can be appropriately controlled based on the estimated intake air amount Ga.

In this embodiment, in order to estimate the intake air amount Ga corresponding to the current ISC flow rate Y1, the first intake air amount map and the determined first intake air amount GaA when the ISC flow rate is the minimum value ISCmin are referred to. The second intake air amount map of the second intake air amount GaB when the ISC flow rate is the maximum value ISCmax is shown. Then, when the current ISC flow rate Y1 is a value between the minimum value ISCmin and the maximum value ISCmax, these first intake air flows are calculated based on the relationship between the current ISC flow rate Y1 and the maximum value ISCmax and the minimum value ISCmin of the ISC flow rate. The amount GaA and the second intake air amount GaB are interpolated to estimate the intake air amount Ga. Here, the intake air amount map that determines the intake air amount Ga based on the relationship between the throttle opening TA and the engine speed NE is originally preferably set for each value of the ISC flow rate, and has a large number of intake air amounts. map. However, storing many intake air quantity maps in advance in the memory of ECU 20 leads to an increase in manufacturing cost. In this regard, in this embodiment, only the first intake air amount map and the second intake air amount map are provided, and an increase in manufacturing cost can be suppressed.

<Second Embodiment>

Next, a second embodiment embodying a fuel injection amount control device for an engine according to the present invention will be described in detail with reference to the drawings.

In addition, in the following description, the same code|symbol is attached|subjected to the same reference numeral as the said 1st Embodiment, and description is abbreviate|omitted, and a different point is mainly demonstrated. In the present embodiment, a part of the configuration differs from the first embodiment in terms of the content of the intake air amount calculation program for estimating and calculating the intake air amount Ga.

Generally, in the intake passage 6 and the bypass passage 10 , deposits may adhere to the inner walls to narrow the flow path area, and deposits may also adhere to the throttle valve 9 and the ISC valve 11 . In addition, the amount of deposited deposits increases over time. If such deposits adhere to the air intake system, they will become an obstacle to the intake air flow, so it is difficult to maintain the original intake air volume Ga of the product as it is.

In FIG. 7 , variations (individual differences) in the ISC flow rate characteristics immediately after the engine system is manufactured (initial product) are shown in a graph. In FIG. 7 , the thick line indicates the median value of the variation in the ISC flow rate characteristic, the upper dotted line indicates the upper limit value of the variation, and the lower dotted line indicates the lower limit value of the variation. Thus, it can be seen that at the initial stage of the product, there is variation in the ISC flow rate characteristics among the various products. On the other hand, in FIG. 8, the annual change of the ISC flow rate characteristic is shown graphically. In Fig. 8, the thick line represents the initial value of the ISC flow characteristics, the dotted line represents the state after the annual change (shorter driving distance stage) caused by sediment adhesion, and the single-dot dash line represents the long-term change caused by sediment adhesion. The state after the annual change (a phase with a longer driving distance). Thus, it can be seen that even in the same product, the ISC flow rate characteristics change over the years due to deposits adhering to the bypass passage 10 and the ISC valve 11 .

In FIG. 9 , the deviation (individual difference) in the characteristic (intake air amount characteristic) of the intake air amount Ga drawn into the combustion chamber 8 at the initial stage of the product with respect to the throttle valve opening TA is shown in a graph. In FIG. 9 , the thick line indicates the median value of the variation in the intake air amount characteristic, the upper broken line indicates the upper limit value of the variation, and the lower broken line indicates the lower limit value of the variation. The intake air amount characteristic shown in FIG. 9 means the characteristic of the sum of the throttle flow rate Fs passing through the throttle valve 9 and the ISC flow rate Fi passing through the ISC valve 11 . Here, the intake air amount Ga during idling when the throttle opening TA is "0" includes the throttle flow rate Fs passing through the throttle valve 9 slightly opened and the ISC flow rate Fi passing through the ISC valve 11 opened to a predetermined opening degree. Thus, it can be seen that at the initial stage of the product, there is variation in the air intake amount characteristic among the products. On the other hand, FIG. 10 shows the annual change of the intake air amount characteristic in a graph. In Fig. 10, the thick line indicates the initial value of the intake air quantity characteristic, the dotted line indicates the state after the yearly change (short driving distance stage) caused by sediment adhesion, and the one-dot chain line indicates the state caused by sediment adhesion. The state after the yearly change (the stage where the driving distance is longer). Thus, it can be seen that even in the same product, the intake air quantity characteristic changes over the years due to deposits adhering to the throttle valve 9 and the ISC valve 11 .

Therefore, in the present embodiment, it is properly estimated that the intake air is sucked into the combustion chamber 8 in accordance with the above-mentioned variation (individual difference) in the intake air amount characteristic and the annual change in the intake air amount characteristic due to deposit adhesion. The ECU 20 executes the intake air amount calculation process as follows to appropriately control the fuel injection amount TAU supplied to the engine 3 .

FIG. 11 shows an intake air amount calculation routine for estimating and calculating the intake air amount Ga in a flowchart. In the flowchart of FIG. 11 , the processing contents of steps 100 to 140 are the same as the processing contents of steps 100 to 140 of the flowchart of FIG. 2 . In the flowchart of FIG. 11, the processing of steps 111, 121 to 123, and 160 are newly added. FIG. 12 shows the ISC flow rate characteristics in a graph. The ECU 20 periodically executes the routine shown in FIG. 11 every predetermined period.

When the process shifts to this routine, after the processes of steps 100 and 110 are executed, in step 111, the ECU 20 reads the ISC flow rate learning reference value A1 (see FIG. 12 ). This ISC flow rate learning reference value A1 is a value used in the ISC control performed separately, and means the reference value of the ISC flow rate with respect to the reference value of the ISC learning value.

Next, in step 120 , the ECU 20 obtains the ISC flow rate Y1 relative to the current ISC control amount y1 by referring to the ISC flow rate characteristic shown in FIG. 12 .

Next, in step 121 , ECU 20 obtains ISC flow learning value X1 (ISC flow rate) relative to ISC learning value x1 (ISC control amount) obtained this time by referring to the ISC flow rate characteristic shown in FIG. 12 . Here, the ISC learning value x1 means an ISC control amount obtained when the ISC valve 11 is feedback-controlled so that the engine speed NE becomes a predetermined idle speed when the throttle valve 9 is fully closed. The ECU 20 performs ISC control when the engine 3 is idling.

Next, in step 122, ECU 20 calculates ISC flow rate learning correction value B1. The ECU 20 can obtain the ISC flow rate learning correction value B1 according to the following calculation formula (4).

B1←X1+A1－X1...(4)

Next, in step 123, the ECU 20 calculates the corrected ISC flow rate C1. The corrected ISC flow rate C1 means the ISC flow rate corrected to reflect the individual differences in the bypass passage 10 and the ISC valve 11 and the annual variation due to deposit adhesion. The ECU 20 can obtain the corrected ISC flow rate C1 from the following calculation formula (5).

C1←Y1－X1+B1...(5)

That is, in the calculation formula (5), by adding the difference between the ISC flow rate learning correction value B1 (=ISC flow rate learning reference value) and the ISC flow rate learning value X1 (the ISC flow rate learning value change amount) to the current ISC flow rate Y1 , get the corrected ISC flow rate C1. In this way, the corrected ISC flow rate C1 is obtained by correcting the current ISC flow rate Y1 based on the learned ISC flow rate value X1 and the learned correction value B1 of the ISC flow rate reflecting changes over time.

Thereafter, after executing the processes of steps 130 and 140 , in step 160 , ECU 20 calculates the intake air amount Ga, and returns the process to step 100 . The ECU 20 can obtain the intake air amount Ga from the following calculation formula (6).

Ga←GaA+(GaB－GaA)*(C1－ISCmin)/(ISCmax－ISCmin)...(6)

That is, in the calculation formula (6), (C1−ISCmin) means the difference between the corrected ISC flow rate C1 and the minimum value ISCmin of the ISC flow rate (corrected minimum side ISC flow rate difference). Therefore, in formula (6), the current progress is estimated by interpolating between the first intake air amount GaA and the second intake air amount GaB according to the ratio of the corrected minimum side ISC flow difference to the maximum and minimum ISC flow difference. Capacity Ga. Furthermore, the intake air amount Ga estimated as described above is reflected in the execution of the fuel injection amount control routine shown in FIG. 6 as in the first embodiment.

According to the fuel injection amount control device for the engine of the present embodiment described above, unlike the first embodiment, the current ISC flow rate is corrected based on the current ISC flow rate learning value X1 and the ISC flow rate learning correction value B1 reflecting changes over time. Y1, calculate the corrected ISC flow rate C1. Furthermore, the current intake air amount Ga is estimated by interpolating between the first intake air amount GaA and the second intake air amount GaB based on the relationship between the corrected ISC flow rate C1 and the maximum value ISCmax and the minimum value ISCmin of the ISC flow rate. . Thereby, the intake air amount Ga that has reflected the secular variation or the like caused by deposit adhesion or the like in the intake system including the throttle valve 9 and the ISC valve 11 is estimated. Therefore, in the present embodiment, in addition to the effect of the first embodiment, it is possible to estimate a more accurate intake air amount Ga reflecting the state of deposition of deposits on the intake system including the throttle valve 9 and the ISC valve 11. , the fuel injection amount TAU can be more appropriately controlled based on the estimated intake air amount Ga.

FIG. 13 shows the effects related to the fuel injection amount control of the present embodiment. FIG. 13 graphically shows changes in the air-fuel ratio learning value with respect to the learning region (engine speed NE) during engine operation. Here, the air-fuel ratio learning value means an increase/decrease value with respect to the basic fuel injection amount bTAU for bringing the actual air-fuel ratio closer to the target air-fuel ratio. Therefore, it means that the closer the learned air-fuel ratio value is to "0", the more suitable the intake air amount Ga is to the standard value. In FIG. 13 , the solid line indicates the present embodiment, and the broken line indicates the conventional example. As shown in FIG. 13 , in the present embodiment, it can be seen that the air-fuel ratio learning value falls within the range of "about ±0.05" in the entire learning region, and the intake air amount Ga fits the standard value. On the other hand, in the conventional example, it can be seen that as the learning region shifts from idling to high speed, the air-fuel ratio learning value increases from "approximately -0.5" to "approximately -0.03" on the rich side, and the intake air amount Ga is released from the standard value and does not fit the standard value. The superiority of the fuel injection amount control of this embodiment can be confirmed from the comparison with this conventional example.

<Third Embodiment>

Next, a third embodiment embodying a fuel injection amount control device for an engine according to the present invention will be described in detail with reference to the drawings.

In this embodiment, a part of the configuration differs from the second embodiment in terms of the content of the intake air amount calculation program for estimating and calculating the intake air amount Ga. FIG. 14 shows a flow chart of an intake air amount calculation routine in this embodiment. In the flowchart of FIG. 14 , the processing contents other than steps 125 and 126 are the same as those of the flowchart of FIG. 11 .

When the process shifts to this routine, after executing the processes of steps 100, 110, 111, 120, and 121, in step 125, the ECU 20 calculates the ISC learning correction value X2 from the ISC flow rate learning value X1. Here, the ECU 20 obtains the ISC learning correction value X2 for the ISC flow rate learning value X1 by referring to the correction map shown in FIG. 15 . In the map of FIG. 15 , it is set so that the ISC learning correction value X2 increases as the ISC flow learning value X1 increases, and in a part of it, even if the ISC flow learning value X1 increases, the ISC learning correction value X2 is set to be constant. Value of dead zone NZ. In this dead zone NZ, when the ISC flow rate learning value X1 is within a predetermined range including the ISC flow rate learning reference value A1 as a predetermined reference value, the ISC learning correction value X2 is constant at the ISC flow rate learning reference value A1. of. In this dead zone NZ, the ISC learning correction value X2 is set to an appropriate value that can be replaced by a change in the intake air amount Ga with reference to the flow rate deviation in each of the throttle valve 9 and the ISC valve 11 .

Reporter, in step 126, the ECU 20 calculates the corrected ISC flow rate C1. The ECU 20 can obtain the corrected ISC flow rate C1 from the following calculation formula (7).

C1←Y1－X2+A1...(7)

That is, in the calculation formula (7), the corrected ISC flow rate C1 can be obtained by adding the difference between the ISC flow rate learning reference value A1 and the ISC learning correction value X2 to the current ISC flow rate Y1 . Here, when the ISC flow rate learning value X1 is a value within the range of the insensitive zone NZ in FIG. 15, the ISC learning correction value X2 is set as the ISC flow rate learning reference value A1, that is, the ISC flow rate learning value X1 is corrected The reference value A1 is learned for the ISC flow. Therefore, the corrected ISC flow C1 becomes the current ISC flow Y1.

Thereafter, ECU 20 returns the process to step 100 after executing the processes of steps 130 , 140 , and 160 .

In the above control, in addition to the control content of the second embodiment, when the obtained ISC flow rate learning value X1 is a value within the range of the predetermined insensitive zone NZ including the predetermined ISC flow rate learning reference value A1 , the ECU 20 corrects the ISC flow rate learning value X1 to the ISC flow rate learning reference value A1. Here, the intake air amount Ga is estimated assuming a state before deposits adhere to the bypass passage 10 and the ISC valve 11 and the ISC flow rate learning value X1 increases (the engine system is new). That is, even if the ISC flow rate learning value X1 deviates within the range of the insensitive zone NZ including the ISC flow rate learning reference value A1, the ISC learning correction value X2 can be set to the ISC flow rate learning reference value A1 as a constant value, that is, , and correct the ISC flow learning value X1 to the ISC flow learning reference value A1. Therefore, only when deposits actually adhere to the bypass passage 10 and the ISC valve 11, the ISC learning correction value X2 relative to the ISC flow learning value X1 changes, and the ISC learning correction value X2 is used to correct the ISC flow learning value X1 .

According to the fuel injection amount control device for the engine of the present embodiment described above, even if the obtained ISC flow rate learning value X1 deviates within the range of the predetermined insensitive zone NZ including the predetermined ISC flow rate learning reference value A1, it can Since the ISC flow rate learning value X1 is corrected to the ISC flow rate learning reference value A1 which is a constant value, it is possible to eliminate variations, minute fluctuations, and the like in the ISC flow rate learning value X1. Therefore, in this embodiment, in addition to the effects of the second embodiment, the intake air amount Ga can be stably estimated when the engine system is new, and the intake air amount Ga can be controlled more accurately based on the intake air amount Ga. Fuel injection amount TAU.

In addition, this invention is not limited to each said embodiment, In the range which does not deviate from the summary of invention, a part of structure can be changed suitably and implemented.

(1) In each of the above-mentioned embodiments, the fuel injection amount control of the present invention is implemented as the engine 3 mounted on a two-wheeled vehicle, but it is not limited thereto, and may be implemented as an engine 3 mounted on a four-wheeled vehicle. engine.

(2) In each of the above-described embodiments, the ISC valve 11 having the ISC flow rate characteristics shown in FIGS. 3 and 12 is used, but it is not limited to the ISC flow rate characteristics shown in FIGS. 3 and 12 .

Industrial availability

The present invention can also be applied to an engine system using an α-N system having an intake system including a throttle valve and an ISC valve.

Explanation of reference signs

3. Engine; 4. Injector (fuel injection component); 6. Intake passage; 8. Combustion chamber; 9. Throttle valve; 10. Bypass passage; 11. ISC valve; 20. ECU (control component); 23 , speed sensor (speed detection part); 25, throttle sensor (opening detection part); NE, engine speed; TA, throttle opening; Ga, intake air volume; GaA, the first intake air volume; GaB, the first intake air volume 2Intake air volume; ISCmin, minimum value of ISC flow; ISCmax, maximum value of ISC flow; Y1, current ISC flow; X1, learning value of ISC flow; C1, corrected ISC flow; TAU, fuel injection amount; A1, ISC flow learning reference value (predetermined reference value); NZ, insensitive zone (predetermined range).

Claims (3)

1. A fuel injection quantity control device for an engine, comprising: an intake passage for introducing intake air into the combustion chamber of the engine; a throttle valve for regulating intake air flow in said intake passage; a bypass passage provided on the intake passage bypassing the throttle valve; an ISC valve for regulating intake air flow in the bypass passage; a fuel injection component for injecting fuel into said engine; an opening detection component, which is used to detect the opening of the throttle valve; a rotation speed detection part for detecting the rotation speed of the engine; and a control unit that estimates an amount of intake air introduced into the combustion chamber based on the detected opening of the throttle valve and the detected rotational speed of the engine, and calculates a fuel injection amount based on the estimated intake air amount, The fuel injection member is controlled based on the calculated fuel injection amount, and the fuel injection amount control device of the engine is characterized in that, The control unit has: ISC flow rate characteristic data which presets a relationship between an ISC flow rate flowing in the bypass passage when the throttle valve becomes fully closed and an opening degree of the ISC valve; The maximum and minimum values of the ISC flow rate are preset; The first intake air amount map presets the first intake air amount introduced into the combustion chamber, the opening degree of the throttle valve, and the engine The relationship between the rotational speeds of ; and The second intake air amount map presets the second intake air amount introduced into the combustion chamber, the opening degree of the throttle valve, and the engine The relationship between the rotational speed, The control unit performs the following operations when the engine is running: Referring to the ISC flow rate characteristic data, the current ISC flow rate relative to the current opening of the ISC valve is obtained, The first intake air amount corresponding to the opening degree of the throttle valve and the rotational speed of the engine when the ISC flow rate becomes the minimum value is obtained by referring to the first intake air amount map. , Referring to the second intake air amount map, the second intake air amount corresponding to the opening degree of the throttle valve and the rotational speed of the engine is obtained when the ISC flow rate becomes the maximum value. , Interpolation is performed between the first intake air amount and the second intake air amount based on the relationship between the current ISC flow rate and the maximum value and the minimum value of the ISC flow rate, thereby estimating The current air intake. 2. The fuel injection amount control device for an engine according to claim 1, wherein: The control unit performs the following operations: When the engine is idling, feedback control is performed on the ISC valve in order to adjust the speed of the engine to a predetermined idle speed, and the current ISC control amount for the ISC valve is learned as an ISC learning value, When the engine is running, the ISC flow rate characteristic data is referred to to obtain an ISC flow rate learning value corresponding to the current ISC learning value, Correcting the current ISC flow according to the current ISC flow learning value, thereby calculating the corrected ISC flow, Interpolation between the first intake air amount and the second intake air amount is performed based on the relationship between the corrected ISC flow rate and the maximum value and the minimum value of the ISC flow rate, thereby estimating The current air intake. 3. The fuel injection amount control device for an engine according to claim 2, wherein: The control unit performs the following operations: When the obtained ISC flow rate learning value is a value within a predetermined range including a predetermined reference value, the ISC flow rate learning value is corrected to the predetermined reference value.