JP2008286086A - Fuel injection control device and fuel injection control system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that it is difficult to inject appropriate quantity of fuel during transient operation of a gasoline engine. <P>SOLUTION: Fuel injection start timing and fuel injection period (injection pulse width τ) are calculated based on the throttle opening and rotation speed at a prescribed angle α of the gasoline engine. Latest throttle opening is taken in at every predetermined rotation angle and an injection pulse width τnew is re-calculated based on this. If the injection pulse width τ calculated in a previous time and the injection pulse width τnew calculated in this time are different, the injection pulse width τ is replaced with the injection pulse width τnew. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection control device and a fuel injection control system for an internal combustion engine that perform fuel injection control by operating a fuel injection valve of the internal combustion engine.

  As this type of fuel injection control device, one that calculates a fuel injection period at a predetermined timing before fuel injection by a fuel injection valve and operates the fuel injection valve based on this is well known. However, in this case, during a transition in which the operating state of the gasoline engine changes, the amount of fuel injected within the injection period calculated at a predetermined timing is not appropriate as the amount of fuel at the actual injection timing. There is a fear.

Therefore, conventionally, as can be seen in, for example, Patent Document 1 below, when the gasoline engine is accelerated, asynchronous injection is performed in which fuel is injected asynchronously with the rotation angle of the output shaft of the gasoline engine according to the continuation of the acceleration request. It has also been proposed.
JP-A-9-317529

  By the way, in the fuel injection control device, the processing is complicated, for example, it is necessary to change the fuel injection control between the steady operation and the acceleration operation. Further, in the above control device, when the gasoline engine decelerates, the same control as that in the steady state of the gasoline engine is performed, so the fuel injection amount may be excessive.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel injection control device for an internal combustion engine that can inject an appropriate amount of fuel even during transient operation of the internal combustion engine. And providing a fuel injection control system.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  The invention according to claim 1 sets the fuel injection period of the internal combustion engine based on the acquisition means for acquiring the detection value by the detection means for detecting the intake equivalent amount of the internal combustion engine and the detection value of the intake equivalent amount. Setting means, and the setting means sets the fuel injection period based on the detected value when fuel is being injected through the fuel injection valve.

  The amount of fuel required for the internal combustion engine varies depending on the intake equivalent amount. On the other hand, during the transient operation of the internal combustion engine, the intake equivalent amount before and after the actual fuel injection is different. For this reason, if the injection amount (fuel injection period) is determined by the intake equivalent amount before fuel injection, there is a possibility that an appropriate amount of fuel cannot be injected. In this regard, in the above invention, by setting the fuel injection period based on the detected value of the intake air equivalent amount during the period in which the fuel is being injected, an appropriate amount of fuel is injected even during transient operation of the internal combustion engine. can do.

  According to a second aspect of the present invention, in the first aspect of the invention, the setting means sets the fuel injection period based on the detected value at a timing prior to fuel injection of the internal combustion engine, and the fuel is injected. And changing means for changing the fuel injection period in accordance with the detected value when the operation is performed.

  In the above invention, by providing the changing means, even if the fuel injection period corresponding to the detected value at the timing prior to fuel injection is not appropriate, this can be changed according to the intake equivalent amount at the time of fuel injection. The fuel injection amount can be set to an appropriate amount.

  According to a third aspect of the present invention, in the invention according to the second aspect, the changing means is calculated this time with means for calculating a fuel injection period based on the detected value each time the fuel is injected. When the comparison means for comparing the fuel injection period and the fuel injection period calculated before that, and the comparison target by the comparison means do not match each other, the previously calculated fuel injection period is the fuel calculated this time And means for replacing with an injection period.

  In the above invention, by comparing the fuel injection period calculated this time with the fuel injection period calculated before that, it is determined whether the previously calculated fuel injection period is an appropriate value for the latest intake equivalent amount. Can be judged. For this reason, it is possible to appropriately change the fuel injection period.

  According to a fourth aspect of the invention, in the third aspect of the invention, when the current timing is delayed with respect to the injection end timing determined by the fuel injection period calculated this time, the end means for immediately ending the fuel injection. Is further provided.

  In the above invention, by providing the end means, the fuel injection is immediately ended when the amount of fuel already injected is excessive with respect to the intake equivalent amount at the timing when the fuel injection period is calculated this time. For this reason, it can suppress that a fuel is injected excessively as much as possible.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the acquisition means detects the detection value detected by the detection means at every predetermined rotation angle of the output shaft of the internal combustion engine. The setting means sets the fuel injection period based on the detection value acquired each time.

  In the above invention, in order to acquire the detection value at every predetermined rotation angle of the output shaft of the internal combustion engine, the detection frequency of the detection value to be referred to when setting the fuel injection period is kept constant regardless of the rotation speed of the internal combustion engine. be able to.

  According to a sixth aspect of the present invention, in the first aspect of the present invention, the intake equivalent amount is adjusted by an intake throttle valve that adjusts a flow area of the intake passage of the internal combustion engine. It is an area.

  In general, an apparatus including an intake throttle valve that adjusts the flow path area is provided with detection means for detecting the adjusted flow path area. In this regard, in the above invention, the fuel injection period can be easily set without providing the intake air amount sensor (mass flow sensor) or the intake pressure sensor by setting the flow passage area to the intake air equivalent amount.

  According to a seventh aspect of the invention, in the sixth aspect of the invention, the setting means is based on relationship information relating a rotational speed of the output shaft of the internal combustion engine, the flow path area, and the fuel injection period. A fuel injection period is set.

  In the above invention, the fuel injection period can be set easily and appropriately by using the relationship information.

  The invention according to claim 8 is a fuel injection control system comprising the fuel injection control device according to any one of claims 1 to 6, the fuel injection valve, and the detection means.

  Hereinafter, an embodiment in which a fuel injection control device according to the present invention is applied to a fuel injection control device of a gasoline engine mounted on a motorcycle will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of an internal combustion engine control system according to the present embodiment. As illustrated, the gasoline engine 10 is a spark ignition reciprocating engine, and includes a cylinder block 12, and a cylinder 14 is formed by the cylinder block 12. The cylinder block 12 is provided with a cooling water passage 16 for circulating cooling water in the gasoline engine 10, and the gasoline engine 10 is cooled by the cooling water. A piston 18 is accommodated in the cylinder 14, and a crankshaft 20 as an output shaft is rotated by the reciprocating motion of the piston 18. A crank angle sensor 22 that outputs a crank angle signal at every predetermined crank angle (for example, at a cycle of 30 ° CA) is provided on the outer peripheral side of the crankshaft 20 so that the rotation angle of the crankshaft 20 can be detected. . A cylinder head is fixed to the upper end surface of the cylinder block 12, and a combustion chamber 24 is defined by the cylinder head, the cylinder block 12, and the piston 18.

  The cylinder head is formed with an intake port (intake port) and an exhaust port (exhaust port) that open to the combustion chamber 24. These intake port and exhaust port are each attached to a camshaft that is linked to the crankshaft 20. It is opened and closed by an intake valve 26 and an exhaust valve 28 driven by a cam (not shown). An intake passage 30 for sucking outside air (fresh air) into the cylinder 14 is connected to the intake port, and an exhaust passage 32 for discharging combustion gas (exhaust gas) from the cylinder 14 to the exhaust port. Is connected. A surge tank 34 whose passage area is enlarged (expanded) is provided in the middle of the intake passage 30 in order to prevent intake pulsation and intake interference.

  In the intake passage 30 (intake passage) of the gasoline engine 10, a throttle valve 38 (intake throttle valve) whose opening degree is mechanically adjusted by a user's operation of the accelerator grip 36, and an opening degree of the throttle valve 38 (throttle opening degree). ) And a throttle sensor 40 for detecting movement (opening fluctuation). The amount of air sucked downstream can be adjusted according to the throttle opening.

  In addition, an electronically controlled fuel injection valve 42 that supplies fuel in the vicinity of the intake port of the cylinder 14 is attached to the intake passage 30. By this fuel injection valve 42, fuel (gasoline) is injected and supplied (port injection) to the intake passage 30, particularly the intake port of the cylinder 14.

  In the gasoline engine 10, the fuel injected by the fuel injection valve 42 (strictly, the mixture with intake air) is ignited to burn the fuel. For this reason, a spark plug 44 equipped with an ignition device or the like composed of an ignition coil or the like is attached to the cylinder head of the gasoline engine 10. That is, when ignition is performed in the gasoline engine 10, a high voltage is applied to the spark plug 44 at a desired ignition timing. By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 44, and the generated spark discharge ignites the air-fuel mixture introduced into the combustion chamber 24, and the reaction between the intake air and the fuel. The fuel burns.

  The electronic control unit (ECU 50) includes a central processing unit (CPU 52) that performs various calculations, a RAM 54 (Random Access Memory) as a main memory that temporarily stores data and calculation results during the calculation, and a program memory. Read-only storage device (ROM 56). Further, the ECU 50 includes an A / D converter 58 that converts output signals of various sensors such as the crank angle sensor 22 and the throttle sensor 40 into digital data.

  The ECU 50 controls the combustion of the gasoline engine 10 by operating various actuators such as a fuel injection valve 42 and an ignition device based on detection values of various sensors such as the crank angle sensor 22 and the throttle sensor 40. In particular, the ECU 50 performs fuel injection control in order to control the combustion state of the gasoline engine 10 as desired. Hereinafter, the fuel injection control according to the present embodiment will be described in detail with reference to FIGS. 2 and 3.

  FIG. 2 is a processing procedure regarding the operation of the fuel injection valve 42 according to the present embodiment. This process is repeatedly executed by the ECU 50, for example, at a predetermined cycle.

  In this series of processes, first, in step S10, it is determined whether or not the specified angle α for calculating the fuel injection timing. Here, the specified angle α is set to an advanced angle side with respect to the crank angle on the most advanced angle side at which fuel injection can be started. When it is determined that the angle is the specified angle α, the throttle opening detected by the throttle sensor 40 and the rotation speed corresponding to the detected value of the crank angle sensor 22 are acquired in step S12. Specifically, the output of the crank angle sensor 22 and the output of the throttle sensor 40 are sequentially taken into the A / D converter 58 and converted into digital data, thereby obtaining digital detection values that can be processed by the CPU 52. In step S14, a command value (command injection start timing TFIN) of the fuel injection start timing for the fuel injection valve is calculated based on the throttle opening θ and the rotational speed. Specifically, the command injection start timing is calculated using a map that defines the relationship between the throttle opening and rotation speed and the command injection start timing.

  In the subsequent step S16, the fuel injection period (injection pulse width τ) by the fuel injection valve 42 is calculated based on the throttle opening and the rotational speed. Specifically, the injection pulse width τ is calculated using a map that defines the relationship between the throttle opening and rotation speed and the command injection start timing. The injection pulse width τ determines the fuel injection amount. That is, the fuel injection amount increases as the injection pulse width τ increases. Incidentally, the injection pulse width τ is set to a larger value as the throttle opening θ is larger and the rotational speed is larger.

  In a succeeding step S18, it is determined whether or not the command injection start time calculated in the step S14 is reached. And it waits until it becomes command injection start time, and when it becomes command injection start time (step S18: YES), by energizing the fuel injection valve 42 in step S20, the fuel injection valve 42 is opened. As a result, fuel is injected into the intake passage 30.

  According to the above processing, the fuel injection amount can be set according to the operation state of the gasoline engine 10 each time. Here, since the throttle opening θ is a parameter for adjusting the intake air amount of the gasoline engine 10, the intake air amount of the gasoline engine 10 can be easily grasped by the throttle opening θ. For this reason, in the present embodiment, it is possible to inject an amount of fuel appropriate for each rotation speed and intake air amount based on the throttle opening and the rotation speed.

  However, the injection pulse width τ calculated by the processing shown in FIG. 2 may not be an appropriate value when the gasoline engine 10 is excessively operated. That is, for example, when the gasoline engine 10 is accelerating, there is a demand for increasing the injection amount as the throttle opening θ increases. However, since the throttle opening θ detected at the specified angle α is smaller than the throttle opening θ when the fuel is actually injected, the amount of fuel is insufficient. Thereby, it becomes difficult to appropriately respond to the user's acceleration request by operating the accelerator grip 36. Further, at this time, even if the air-fuel ratio feedback control is performed by the ECU 50, the feedback characteristic is not in time, and the exhaust characteristics are deteriorated.

  On the other hand, when the gasoline engine 10 is decelerating, there is a demand to reduce the injection amount as the throttle opening θ decreases. However, since the throttle opening θ detected at the specified angle α is larger than the throttle opening θ when the fuel is actually injected, the fuel amount becomes excessive. As a result, even if the air-fuel ratio feedback control is performed by the ECU 50, since the feedback control is not in time, exhaust characteristics are deteriorated.

  Therefore, in the present embodiment, the final injection pulse width τ is changed to the throttle opening θ during the actual injection period by recalculating the injection pulse width τ based on the throttle opening θ when the fuel is being injected. Set based on. FIG. 3 shows a procedure of processing related to the change of the injection pulse width τ. This process is repeatedly executed by the ECU 50 using, for example, a crank angle signal output from the crank angle sensor 22 as a trigger during a period from the completion of the process of FIG. 2 to the end of fuel injection. .

  In this series of processes, first, in step S10, the latest rotation speed is acquired. In the subsequent step S32, the latest throttle opening is acquired. That is, the latest throttle opening is acquired by converting the output signal of the throttle sensor 40 into digital data by the A / D converter 58. In the subsequent step S34, the injection pulse width τnew is calculated based on the rotational speed acquired in step 30 and the throttle opening acquired in step S32. Here, the injection pulse width τnew is calculated by performing the same process as that shown in step S16 of FIG.

  In the subsequent step S36, it is determined whether or not the currently set injection pulse width τ matches the injection pulse width τnew calculated in the current step S34. In this process, whether or not the currently set injection pulse width τ is appropriate for the latest rotation speed acquired in step 30 and the latest throttle opening θ acquired in step S32. Is to judge. If a negative determination is made in step S36, the process proceeds to step S38. In step S38, it is determined whether or not the period from the start of fuel injection (injection period T) is longer than the latest injection pulse width τnew calculated in step S34. This process determines whether or not the fuel injection should be stopped immediately. When the injection period T is longer than the injection pulse width new, the injection amount by the current fuel injection already exceeds the appropriate injection amount for the latest throttle opening θ, and it is desirable to immediately stop the fuel injection. Judge.

  That is, when an affirmative determination is made in step S38, energization of the fuel injection valve 42 is stopped in step S40. On the other hand, when a negative determination is made in step S38, the process proceeds to step S42. In step S42, the injection pulse width τ is changed to the latest injection pulse width τ calculated in step S34.

  When an affirmative determination is made in step S36 or when the processes in steps S40 and S42 are completed, this series of processes is temporarily terminated.

  FIG. 4 illustrates a setting mode of the injection pulse width τ according to the present embodiment. 4A shows the crank angle signal based on the output of the crank angle sensor 22, FIG. 4B shows the injection pulse width, and FIG. 4C shows the transition of the throttle opening.

  As shown in FIG. 4, the throttle opening is increased during the acceleration operation of the gasoline engine 10. Then, at the specified angle α, the injection pulse width τ is calculated based on the throttle opening and the rotational speed at that time. Thereafter, the injection pulse width τ is recalculated at every predetermined rotation angle. At this time, if the previously calculated injection pulse width τ is different from the current injection pulse width τnew, the injection pulse width τ is changed. In particular, during the acceleration operation of the gasoline engine 10, the throttle opening increases, so the change of the injection pulse width τ is a change to the side of expanding the pulse width.

  FIG. 5 illustrates an example of how the injection pulse width τ is set during the deceleration operation of the gasoline engine 10. 5A to 5C correspond to FIGS. 4A to 4C.

  As shown in the figure, in the case of deceleration operation, the throttle opening decreases, so that the change of the injection pulse width is changed to the side of decreasing the pulse width.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The injection pulse width τ is set based on the throttle opening when fuel is being injected through the fuel injection valve 42. Thereby, an appropriate amount of fuel can be injected even during the transient operation of the gasoline engine 10.

  (2) The injection pulse width τ is set based on the throttle opening at the timing prior to the fuel injection of the gasoline engine 10, and the injection pulse width τ is changed according to the throttle opening when the fuel is being injected. As a result, even if the injection pulse width corresponding to the throttle opening at the timing prior to fuel injection is not appropriate, the fuel injection amount can be changed to an appropriate amount by changing this according to the throttle opening at the time of fuel injection. can do. Furthermore, when the injection pulse width τ is set based on the throttle opening at a timing prior to fuel injection, the detected value of the throttle opening cannot be obtained due to noise or the like when fuel is injected. Even if it exists, the injection pulse width τ can be set.

  (3) When the injection pulse width τnew calculated this time and the injection pulse width τ previously calculated do not coincide with each other, the injection pulse width τ was replaced with the injection pulse width τnew. Thereby, the injection pulse width τ can be appropriately changed.

  (4) When the current timing is delayed with respect to the injection end timing determined by the injection pulse width τnew calculated this time, the fuel injection is immediately ended. Thereby, it can suppress as much as possible that fuel is injected excessively.

  (5) The A / D conversion of the output of the throttle sensor 40 was performed at every predetermined rotation angle of the crankshaft 20, and the injection pulse width τ was changed using the A / D converted data each time. Thereby, irrespective of the rotation speed of the gasoline engine 10, the acquisition frequency of the A / D conversion value (detection value) of the throttle opening referred to when setting the injection pulse width τ can be kept constant. In particular, in the present embodiment, since the gasoline engine 10 is mounted on a motorcycle, the rotational speed thereof tends to be particularly high. For this reason, when A / D conversion is performed in a time cycle, when it is attempted to sufficiently secure the throttle opening acquisition frequency in the high rotation speed region, the A / D conversion frequency becomes excessively high in the idle rotation speed region. . On the other hand, by performing A / D conversion at a rotation angle cycle, A / D conversion can be performed at an appropriate frequency from the idle rotation speed region to the high rotation speed region.

  (6) The injection pulse width τ is calculated based on the opening of the throttle valve 38 that adjusts the flow passage area of the intake passage 30 of the gasoline engine 10. Thus, the injection pulse width τ can be easily set without providing an intake air amount sensor (mass flow sensor) or an intake pressure sensor.

  (7) The injection pulse width τ is set based on a map that associates the throttle opening and rotation speed with the injection pulse width τ. Thereby, the injection pulse width τ can be set easily and appropriately.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  The intake air equivalent amount of the gasoline engine 10 is not limited to the throttle opening, and may be, for example, an intake air flow rate or an intake air pressure.

  In the above embodiment, the injection pulse width is directly calculated based on the intake equivalent amount and the rotation speed. However, instead of this, the injection amount may be calculated. In this case, a process for converting the injection amount into the injection pulse width is separately performed. At this time, if the conversion is performed according to the pressure difference between the pressure in the intake passage 30 and the pressure in the fuel injection valve 42, the injection amount can be controlled with higher accuracy. In place of this differential pressure, intake pressure may be used.

  In the above embodiment, the injection pulse width is set before the fuel injection is started. However, the present invention is not limited to this, and only the command injection start time may be set before the fuel injection is started. The injection pulse width τ can also be set based on the latest throttle opening by performing the processing shown in FIG. 3 after the fuel injection is started.

  In the process shown in FIG. 3, when the A / D conversion value of the current throttle opening is more than a predetermined distance from the A / D conversion value of the previous throttle opening, the A / D of the current throttle opening Since the reliability of the conversion value is low, the change of the injection pulse width τ based on the reliability may be prohibited. Instead of this, the A / D conversion value for the current throttle opening and the previous throttle opening multiplied by a predetermined coefficient and added to each other are subjected to a so-called weighted average process. It may be a degree. Thereby, the influence of noise etc. can be removed suitably.

  The internal combustion engine is not limited to an intake port type spark ignition type internal combustion engine such as an intake port type gasoline engine 10 or the like. However, it is desirable that the actual opening / closing timing is not excessively delayed with respect to the opening / closing command for the fuel injection valve 42, in other words, the opening command period and the actual fuel injection period are surely overlapped.

  The internal combustion engine is not limited to that mounted on a motorcycle, and may be mounted on a four-wheeled vehicle, for example.

The figure which shows the whole structure of the control system of the gasoline engine concerning one Embodiment. The flowchart which shows the procedure of the setting process of the fuel injection timing concerning the embodiment. The flowchart which shows the procedure of the change process of the injection pulse width concerning the embodiment. The time chart which shows the change process aspect of the injection pulse width concerning the embodiment. The time chart which shows the change process aspect of the injection pulse width concerning the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Gasoline engine, 22 ... Crank angle sensor, 38 ... Throttle valve, 40 ... Throttle sensor, 50 ... ECU (fuel injection control apparatus).

Claims (8)

In a fuel injection control device for an internal combustion engine that performs fuel injection control by operating a fuel injection valve of the internal combustion engine,
An acquisition means for acquiring a detection value by a detection means for detecting an intake air equivalent amount of the internal combustion engine;
Setting means for setting a fuel injection period of the internal combustion engine based on the detected value of the intake air equivalent amount;
The fuel injection control device for an internal combustion engine, wherein the setting means sets the fuel injection period based on the detected value when fuel is being injected through the fuel injection valve.   The setting means sets the fuel injection period based on the detected value at a timing prior to fuel injection of the internal combustion engine, and sets the fuel injection period according to the detected value when the fuel is being injected. The fuel injection control device for an internal combustion engine according to claim 1, further comprising changing means for changing.   The changing means includes means for calculating a fuel injection period based on the detected value each time the fuel is injected, a fuel injection period calculated this time, and a fuel injection period calculated before that. 3. A comparison means for comparing, and means for replacing the previously calculated fuel injection period with the currently calculated fuel injection period when the comparison objects by the comparison means do not match each other. A fuel injection control device for an internal combustion engine as described.   The internal combustion engine according to claim 3, further comprising an end unit that immediately ends fuel injection when a current timing is delayed with respect to an injection end timing determined by the fuel injection period calculated this time. Fuel injection control device. The acquisition means acquires the detection value detected by the detection means for each predetermined rotation angle of the output shaft of the internal combustion engine each time,
The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the setting means sets the fuel injection period based on a detection value acquired each time.   6. The internal combustion engine according to claim 1, wherein the intake equivalent amount is a flow passage area adjusted by an intake throttle valve that adjusts a flow passage area of the intake passage of the internal combustion engine. Fuel injection control device.   7. The fuel injection period according to claim 6, wherein the setting means sets the fuel injection period based on relationship information relating a rotational speed of the output shaft of the internal combustion engine and the flow path area to the fuel injection period. A fuel injection control device for an internal combustion engine. A fuel injection control device according to any one of claims 1 to 7,
The fuel injection valve;
And a fuel injection control system.

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