JP4000539B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection control device for an internal combustion engine in which an intake valve is provided in an intake passage upstream of a throttle valve.
[0002]
[Prior art]
For example, in a motorcycle, an intake valve is provided in the intake passage upstream of the throttle valve, and the engine output is suppressed by closing the intake valve and narrowing the intake passage during sudden acceleration, etc., and reducing the intake air amount. Some of them are designed to reduce noise. The fuel injection amount calculation method includes a method for calculating the fuel injection amount from the throttle opening and the internal combustion engine speed, a method for calculating the fuel injection amount from the intake pressure and the internal combustion engine speed, There is a method of using a calculation method together.
[0003]
[Problems to be solved by the invention]
By the way, even if the throttle opening is largely opened, when the intake valve is closed, the throttle opening is substantially the same as when the throttle opening is closed, and the intake air amount corresponding to the throttle opening cannot be obtained. Therefore, in a system that calculates the fuel injection amount from the throttle opening and the engine speed, when the intake valve is closed, the fuel injection amount cannot be calculated accurately, the air-fuel ratio deviates greatly, and exhaust emission is reduced. Causes it to go bad.
[0004]
In general, in the low load range, calculating the fuel injection amount from the intake pressure and the engine speed can calculate the fuel injection amount more accurately than calculating from the throttle opening and the engine speed. In the region, the fuel injection amount is calculated from the intake pressure and the engine speed, and in the middle load / high load region, the fuel injection amount is calculated from the throttle opening and the engine speed. However, since the period during which the intake valve is closed (during sudden acceleration, etc.) belongs to a high load region in which the fuel injection amount is calculated from the throttle opening and the engine speed, the throttle opening and The fuel injection amount is calculated from the engine speed, and the fuel injection amount cannot be calculated accurately.
[0005]
Also, if the intake valve breaks down and closes, the motorcycle must be evacuated to a repair shop. However, in the conventional system, the throttle opening and engine speed can be reduced even when the intake valve is abnormal. Since the fuel injection amount is calculated from the number, the fuel injection amount at the time of evacuation traveling cannot be calculated with high accuracy, and the exhaust emission deteriorates.
[0006]
Accordingly, a first object of the present invention is to enable accurate calculation of the fuel injection amount even during a period in which the intake valve is closed, and to reduce exhaust emissions. When the intake valve becomes abnormal, it is detected so that the fuel injection amount for the evacuation travel can be accurately calculated, and the exhaust emission can be reduced.
[0007]
[Means for Solving the Problems]
In order to achieve the first object, in claim 1 of the present invention, the fuel injection amount calculating means calculates the fuel injection amount from the throttle opening and the internal combustion engine speed in a predetermined operation region, In the operation region, the fuel injection amount is calculated from the intake pressure and the internal combustion engine speed, but it is monitored whether the intake valve is closed, and it is determined that the intake valve is closed even in the predetermined operation region. If so, the fuel injection amount is calculated from the intake pressure and the internal combustion engine speed. That is, the intake pressure varies depending on the throttle opening and the opening / closing of the intake valve. When the intake valve is closed, the intake pressure is the data that best reflects the intake air amount. Therefore, when the intake valve is closed even in the predetermined operating region, the fuel injection amount corresponding to the actual intake air amount can be accurately calculated by calculating the fuel injection amount from the intake pressure and the internal combustion engine speed. It can be calculated well, the deviation of the air-fuel ratio can be reduced, and the exhaust emission can be reduced.
[0008]
In order to achieve the second object, according to claim 2 of the present invention, an intake pressure estimating means for calculating an intake pressure estimated value from the throttle opening and the internal combustion engine speed, and an intake pressure detecting means are used. An abnormality detecting means for detecting an abnormality of the intake valve based on a deviation between the intake pressure estimated by the intake pressure estimating means and the intake pressure estimated value calculated by the intake pressure estimating means. When an abnormality is detected, the fuel injection amount is calculated from the intake pressure and the internal combustion engine speed. In this way, even if the intake valve breaks down and closes, it can be detected, and when the abnormality is detected, the fuel injection amount is calculated from the intake pressure and the internal combustion engine speed. By calculating, the fuel injection amount for the evacuation travel can be calculated with high accuracy, and the exhaust emission can be reduced .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment (1)]
Hereinafter, an embodiment (1) in which the present invention is applied to a motorcycle will be described with reference to FIGS. 1 and 2. An intake manifold 12 is connected to the intake port 10 of each cylinder of the engine 11 which is an internal combustion engine, and an air box 13 is connected to the upstream side of the intake manifold 12 of each cylinder, and is sucked into the air box 13. Air is sucked into the intake manifold 12 of each cylinder. An air cleaner (not shown) is mounted in the air box 13, and an intake air temperature sensor 14 for detecting the intake air temperature is attached to the air box 13. A throttle valve 15 is attached in the middle of the intake manifold 12 of each cylinder, and the opening (throttle opening) of the throttle valve 15 is detected by a throttle opening sensor 16 (throttle opening detecting means). Further, an intake pressure sensor 17 (intake pressure detecting means) for detecting intake pressure is provided on the downstream side of the throttle valve 15 in the intake manifold 12, and a fuel injection valve 18 is provided in the vicinity of the intake port 10 of each cylinder. Is attached.
[0010]
An intake valve 33 that opens and closes the inlet of the intake manifold 12 of each cylinder is provided in an air box 13 that is an intake passage upstream of the throttle valve 15. The intake valve 33 is a motor 34 (intake valve drive). Means). The intake valve 33 is normally held in an open state, and the intake valve 33 is driven in a closing direction by a motor 34 in a specific operation region where noise needs to be suppressed, such as during sudden acceleration. The opening area of the 12 inlet portions is narrowed, and the intake air amount is reduced.
[0011]
On the other hand, the fuel pumped up from the fuel tank 19 by the fuel pump 20 is sent to the fuel pipe 21 → the fuel filter 22 → the fuel pipe 23 → the delivery pipe 24, and is distributed to the fuel injection valve 18 of each cylinder. Excess fuel in the delivery pipe 24 is returned to the fuel tank 19 through a path of the pressure regulator 25 → the return pipe 26. The pressure regulator 25 adjusts the fuel pressure in the delivery pipe 24 so that the differential pressure between the fuel pressure in the delivery pipe 24 and the intake pressure is constant.
[0012]
An ignition plug 27 is attached to the cylinder head of the engine 11 for each cylinder, and a high voltage generated on the secondary side of the ignition coil 28 at each ignition timing is applied to the ignition plug 27 of each cylinder and ignited. The engine 11 includes an engine speed sensor 29 (rotation speed detection means) that outputs a pulse signal (crank angle signal) at every predetermined crank angle in order to detect the engine speed, and a cylinder discrimination sensor that discriminates a specific cylinder. 30 and a water temperature sensor 31 for detecting the engine cooling water temperature are attached. An atmospheric pressure sensor 32 for detecting atmospheric pressure is attached to a predetermined position of the vehicle body.
[0013]
The output signals of these atmospheric pressure sensors 32 and the output signals of various sensors such as the intake pressure sensor 17 described above are input to the engine control circuit 35. The engine control circuit 35 is mainly composed of a microcomputer, and the built-in ROM 45 (storage medium) has various control routines such as an ignition control routine, a fuel injection control routine in FIG. An engine control program is stored.
[0014]
The engine control circuit 35 functions as a fuel injection amount calculation means in the claims by executing the fuel injection control routine of FIG. Hereinafter, the processing content of this fuel injection control routine will be described.
[0015]
This routine is executed immediately before the fuel injection timing of each cylinder. When this routine is started, first, at step 101, the engine speed NE detected from the output signal of the engine speed sensor 29 is read, and at the next step 102, the output signal of the intake pressure sensor 17 is smoothed. The value (intake pressure) Pb is read. Further, after reading the value (atmospheric pressure) Pa obtained by smoothing the output signal of the atmospheric pressure sensor 32 in step 103, the output signal (throttle opening) TVA of the throttle opening sensor 16 is read in step 104.
[0016]
Thereafter, in step 105, the differential pressure between the intake pressure Pb and the atmospheric pressure Pa, that is, the relative intake pressure (Pa-Pb) is calculated, and then in step 106, it is used in the low load region and the closed region of the intake valve 33. The basic injection time TPD is calculated based on the relative intake pressure (Pa-Pb) and the engine speed NE. In this calculation method, a relationship between the relative intake pressure (Pa−Pb), the engine speed NE, and the basic injection time TPD is obtained in advance by experiments or simulations, and a two-dimensional map of the basic injection time TPD is created. Is stored in the ROM 45 of the engine control circuit 35, and in step 106, this map is searched to calculate the basic injection time TPD corresponding to the current relative intake pressure (Pa-Pb) and the engine speed NE. .
[0017]
In the next step 107, the basic injection time TPA used in the middle load / high load region is calculated based on the throttle opening VTA and the engine speed NE. In this calculation method, a two-dimensional map of the basic injection time TPA using the throttle opening VTA and the engine speed NE as parameters is created in advance by experiments or simulations, and this map is stored in the ROM 45 of the engine control circuit 35. In step 107, the map is searched to calculate a basic injection time TPA according to the current throttle opening VTA and the engine speed NE.
[0018]
Thereafter, in step 108, it is determined whether or not the current operation region is a low load region. If the current operation region is a low load region, the process proceeds to step 111, and the basic injection time TP used for calculating the final injection time TAU is as follows. In step 106, the TPD calculated from the relative intake pressure and the engine speed NE is used.
[0019]
On the other hand, in the middle load / high load region, the routine proceeds from step 108 to step 109, where it is determined whether or not the intake valve 33 is closed by a signal output from the engine control circuit 35 to the motor 34 of the intake valve 33, If the intake valve 33 is closed, the routine proceeds to step 111, where the TPD calculated from the relative intake pressure and the engine speed NE in step 106 is used as the basic injection time TP used for calculating the final injection time TAU. On the other hand, if the intake valve 33 is opened, the routine proceeds from step 109 to step 110, where the throttle opening VTA and the engine speed NE are determined in step 107 as the basic injection time TP used to calculate the final injection time TAU. TPA calculated from the above is used.
[0020]
After determining the basic injection time TP to TPD or TPA as described above, various correction coefficients K are calculated in step 112. For example, various corrections such as a warm-up increase correction coefficient according to the output signal (cooling water temperature) of the water temperature sensor 31, an increase correction coefficient after startup, an intake air temperature correction coefficient according to the output signal (intake air temperature) of the intake air temperature sensor 14, etc. The coefficient K is calculated.
[0021]
Thereafter, in step 113, the response delay time of the fuel injection valve 18, that is, the invalid injection time TV is calculated based on the power supply voltage, and in step 114, the pulse width of the injection pulse output to the fuel injection valve 18 is obtained. The final injection time TAU is calculated by the following equation using the basic injection time TP, various correction coefficients K, and the invalid injection time TV.
TAU = TP × K + TV
[0022]
According to the embodiment (1) described above, even in the operation region using the basic injection time TPA calculated from the throttle opening degree VTA and the engine speed NE, the relative intake pressure and the engine are maintained during the period when the intake valve 33 is closed. The basic injection time TPD calculated from the rotational speed NE is used. That is, the intake pressure varies depending on the throttle opening VTA and the opening / closing of the intake valve 33, and during the period in which the intake valve 33 is closed, the intake pressure is the data that best reflects the intake air amount. Therefore, as in the above embodiment (1), when the intake valve 33 is closed, if the basic injection time TPD calculated from the relative intake pressure and the engine speed NE is used, the actual intake air amount Accordingly, the final injection time TAU (fuel injection amount) corresponding to can be calculated with high accuracy, the deviation of the air-fuel ratio can be reduced, and the exhaust emission can be reduced.
[0023]
In the embodiment (1), the intake pressure Pb is converted into the relative intake pressure and used, but the absolute pressure of the intake pressure Pb may be used. Further, in step 102 in FIG. 2, a value obtained by smoothing the output signal of the intake pressure sensor 17 (an average value of the intake pressure) is used as the intake pressure Pb, but the minimum pressure of the intake pressure that decreases due to the intake stroke ( Bottom pressure) may be used.
[0024]
[Embodiment (2)]
3 and 4 show the flow of processing of the intake valve abnormality detection routine and the fuel injection control routine used in the embodiment (2) of the present invention. In the present embodiment (2), the abnormality / normality of the intake valve 33 is determined by the intake valve abnormality detection routine of FIG. 3, and when the abnormality of the intake valve 33 is detected, the fuel injection control routine of FIG. The fuel injection amount is calculated from the engine speed NE. The processing contents of each routine will be described below. The system configuration of the embodiment (2) is the same as the configuration of FIG. 1 described in the embodiment (1).
[0025]
The intake valve abnormality detection routine of FIG. 3 is executed, for example, immediately before the fuel injection timing of each cylinder, and functions as an abnormality detection means in the claims. When this routine is started, first, in step 201, the output signal (throttle opening) TVA of the throttle opening sensor 16 is read, and in the next step 202, the engine speed detected from the output signal of the engine speed sensor 29 is read. Read the number NE. Thereafter, in step 203, an estimated intake pressure value Pbo is calculated from the throttle opening TVA and the engine speed NE. The intake pressure estimated value Pbo may be calculated using a map or the like set in advance using the throttle opening TVA and the engine speed NE as parameters. The intake pressure estimated value Pbo may be obtained only from the throttle opening TVA. The processing in step 203 serves as intake pressure estimation means in the claims.
[0026]
In the next step 204, after the value (actual intake pressure) Pb obtained by smoothing the output signal of the intake pressure sensor 17 is read, the absolute value of the deviation between the actual intake pressure Pb and the estimated intake pressure Pbo | Pb−Pbo | is compared with the abnormality determination value, and if | Pb−Pbo | ≧ abnormality determination value, the process proceeds to step 206, where it is determined that the intake valve 33 is abnormal, and the intake valve abnormality flag means “abnormal”. Set to 1 ”. On the other hand, if | Pb−Pbo | <abnormality determination value, the routine proceeds to step 207 where it is determined that the intake valve 33 is normal and the intake valve abnormality flag is set to “0” meaning normal. .
[0027]
The abnormality detection method of the intake valve 33 is not limited to the above method. For example, the abnormality / normality of the intake valve 33 is determined by detecting the position of the intake valve 33 or the rotation position of the motor 34 with a sensor or the like. Also good.
[0028]
Next, the processing content of the fuel injection control routine of FIG. 4 will be described. This routine is executed immediately before the fuel injection timing of each cylinder. This routine is different from the fuel injection control routine of FIG. 2 only in the process of step 109a.
[0029]
In the fuel injection control routine of FIG. 4, as in the first embodiment, in step 106, the basic injection time TPD used in the low load region is determined based on the relative intake pressure (Pa-Pb) and the engine speed NE. In the next step 107, the basic injection time TPA used in the middle load / high load region is calculated based on the throttle opening degree VTA and the engine speed NE. Thereafter, in step 108, it is determined whether or not the current operation region is a low load region. If the current operation region is a medium load / high load region, the process proceeds to step 109a to determine whether or not the intake valve 33 is abnormal. The determination is made based on whether the intake valve abnormality flag is “1”. If it is determined at step 109a that the intake valve 33 is abnormal, the routine proceeds to step 111, where the basic injection time TP used to calculate the final injection time TAU is calculated from the relative intake pressure and the engine speed NE at step 106. The calculated TPD is used.
[0030]
On the other hand, if it is determined that the intake valve 33 is normal, the routine proceeds from step 109a to step 110, where the basic injection time TP used to calculate the final injection time TAU is determined from the throttle opening VTA and the engine speed NE in step 107. The calculated TPA is used. Since the other processes are the same as the processes of FIG. 2 described in the embodiment (1), description thereof is omitted.
[0031]
According to the embodiment (2) described above, even if the intake valve 33 fails and is closed, the basic injection time TPD calculated from the relative intake pressure and the engine speed NE is used. A fuel injection amount (final injection time TAU) for retreat travel can be calculated with high accuracy, and exhaust emission can be reduced.
[0032]
In the embodiment (2), the intake pressure Pb is converted into the relative intake pressure and used, but the absolute pressure of the intake pressure Pb may be used. Further, in step 204 in FIG. 3, a value (average value of the intake pressure) obtained by smoothing the output signal of the intake pressure sensor 17 is used as the actual intake pressure Pb. However, the minimum pressure of the intake pressure that decreases due to the intake stroke is used. (Bottom pressure) may be used.
[0033]
[Embodiment (3)]
FIG. 5 shows a fuel injection control routine executed in the embodiment (3) of the present invention. This embodiment (3) is an embodiment in the case where the embodiment (1) and the embodiment (2) are combined. Also in the present embodiment (3), the intake valve abnormality detection routine of FIG. 3 described in the embodiment (2) is executed to determine whether the intake valve 33 is abnormal or normal. In the fuel injection control routine of FIG. 5, the low load region basic injection time TPD and the medium load / high load region basic injection time TPA are calculated by the same process as in the embodiment (1) (steps 101 to 107). In the next step 108, it is determined whether or not the current operation region is a low load region, and if it is a medium load / high load region, the process proceeds to step 109 to determine whether the intake valve 33 is closed or not. The determination is made based on the command value of the circuit 35. If it is determined at step 109 that the intake valve 33 is closed, the routine proceeds to step 111 where the basic intake time TP used to calculate the final injection time TAU is set as the basic intake time TP and the engine speed at step 106. TPD calculated from NE is used.
[0034]
On the other hand, if it is determined that the intake valve 33 is open, the routine proceeds from step 109 to step 109a, where it is determined whether or not the intake valve 33 is abnormal depending on whether or not the intake valve abnormality flag is “1”. If it is determined that the intake valve 33 is abnormal, the routine proceeds to step 111 where the TPD calculated from the relative intake pressure and the engine speed NE in step 106 is used as the basic injection time TP used to calculate the final injection time TAU. Is used.
[0035]
On the other hand, if it is determined that the intake valve 33 is normal, the routine proceeds from step 109a to step 110, where the basic injection time TP used to calculate the final injection time TAU is determined from the throttle opening VTA and the engine speed NE in step 107. The calculated TPA is used. Since the other processes are the same as the processes of FIG. 2 described in the embodiment (1), description thereof is omitted.
[0036]
In the system configuration example of FIG. 1, the motor 34 is used as the drive means of the intake valve 33. Instead of this, an electromagnetic actuator such as an electromagnet is used, or the negative pressure in the intake manifold 12 is increased. You may make it use the negative pressure actuator utilized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment (1) of the present invention. FIG. 2 is a flowchart showing a process flow of a fuel injection control routine executed in the embodiment (1). FIG. 4 is a flowchart showing the flow of processing of an intake valve abnormality detection routine executed in the form (2). FIG. 4 is a flowchart showing the flow of processing of a fuel injection control routine executed in the embodiment (2). ) Flowchart showing the flow of fuel injection control routine processing
DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake manifold, 15 ... Throttle valve, 16 ... Throttle opening sensor (throttle opening detecting means), 17 ... Intake pressure sensor (intake pressure detecting means), 18 ... Fuel injection valve, DESCRIPTION OF SYMBOLS 29 ... Engine speed sensor (rotation speed detection means), 32 ... Atmospheric pressure sensor, 33 ... Intake valve, 34 ... Motor (intake valve drive means), 35 ... Engine control circuit (fuel injection amount calculation means, abnormality detection means) 45 ... ROM.

Claims (2)

An intake valve provided in the intake passage upstream of the throttle valve;
An intake valve driving means for normally opening the intake valve and driving the intake valve in a closing direction in a specific operation region to narrow the intake passage;
Throttle opening detecting means for detecting the throttle opening;
Intake pressure detection means for detecting intake pressure;
A rotational speed detecting means for detecting the rotational speed of the internal combustion engine;
Fuel injection amount calculation means for calculating the fuel injection amount from the throttle opening and the internal combustion engine speed in a predetermined operation region, and calculating the fuel injection amount from the intake pressure and the internal combustion engine speed in the other operation region. ,
The fuel injection amount calculating means monitors whether or not the intake valve is closed, and when it is determined that the intake valve is closed even in the predetermined operating range, the intake pressure and the internal combustion engine speed are A fuel injection control device for an internal combustion engine, characterized in that a fuel injection amount is calculated from the internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1,
An intake pressure estimating means for calculating an intake pressure estimated value from the throttle opening and the internal combustion engine speed;
An abnormality detecting means for detecting an abnormality of the intake valve based on a deviation between an intake pressure detected by the intake pressure detecting means and an intake pressure estimated value calculated by the intake pressure estimating means;
The fuel injection amount calculation means calculates the fuel injection quantity from the intake pressure and the internal combustion engine speed when the abnormality detection means detects an abnormality of the intake valve. .

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