JP2004019482A - Stroke distinguishing method of internal combustion engine and stroke distinguishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stroke distinguishing method of an internal combustion engine and a stroke distinguishing device capable of accurately distinguishing a stroke of the internal combustion engine without using a cam angle sensor, and accurately controlling the internal combustion engine with high correlativity with an actual intake volume after distinguishing the stroke. <P>SOLUTION: Intake pressure influenced with an intake pulsing at an intake passage 6 is detected by an intake pressure sensor 21 in driving an engine 3. A lower limit of the intake pressure accompanied by the pulsing is detected by an ECU 20 to turn on a detection flag. A TDC (top dead-center) signal of the engine 3 is detected by the ECU 20 from a rotation speed sensor 23. The TDC signal is detected by The ECU 20 during turning on the lower limit detecting flag to determine that the timing of the detection is at a top dead center of compression. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stroke discrimination method and a stroke discrimination device for discriminating a stroke in an internal combustion engine of a small number of cylinders (particularly, a single cylinder). More specifically, the present invention relates to a stroke discriminating method and a stroke discriminating apparatus for an internal combustion engine that can reduce the system cost and reduce the size and weight of the internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a four-cycle engine, each stroke (an intake stroke, a compression stroke, and an explosion stroke) of an engine is performed using a crank angle sensor for detecting a phase of a crankshaft of the engine and a cam angle sensor for detecting a phase of a camshaft. , And the exhaust stroke). This is because, by performing the stroke determination, the control of the injection system and the ignition system can be changed from two injections / two ignitions / two rotations (strokes) to one injection one ignition / two rotations (strokes). Thereby, the load on the ignition system is reduced and the durability is improved, and the current required for ignition is also reduced, so that the electric load is also reduced. In particular, for a vehicle with a small battery such as a motorcycle, it is possible to contribute to fuel efficiency.
[0003]
However, in a few-cylinder engine such as a motorcycle, there is a problem that there is no room around the engine head, and it is difficult to mount the cam angle sensor. In addition, there is a problem that the system cost is increased when the cam angle sensor is attached.
[0004]
Then, as one of the techniques for solving such a problem, there is one disclosed in Japanese Patent Application Laid-Open No. 2001-207902. This technique is based on an intake stroke (ATDC15 ゜ CA) when a difference between a previous crank angle signal and an intake pressure signal at the time of interruption is negative by a predetermined value (eg, 1130 Pa) or more for the first time during one cycle of a single cylinder four-cycle engine. ). This eliminates the need for a cam angle sensor required for stroke determination, and solves the above problem. ATDC is the abbreviation of crank angle after top dead center, and CA is the abbreviation of crank angle.
[0005]
[Problems to be solved by the invention]
However, the technique disclosed in Japanese Patent Application Laid-Open No. 2001-207902 has a problem that the stroke determination is not performed correctly. In this technique, a stroke is determined based on a difference in intake pressure between TDC and ATDC 15 ° CA. However, since ATDC15 ° CA is an overlap region with the exhaust valve, when backflow from the exhaust or backfire occurs, the backpressure or backfire causes the intake pressure at ATDC15 ° CA to be higher than the normal value. become. Therefore, the relationship between the changes in the intake pressure at TDC and ATDC 15 ° CA is broken, and the stroke determination is not performed correctly.
[0006]
Here, the applicant of the present application has found that in a four-cycle reciprocating engine, the lower limit value of the intake pressure, that is, the detected value near the bottom dead center of the intake stroke, in the fluctuation of the intake pressure due to the pulsation of the intake air, It has been found that the intake pressure reflects the intake volume best. Then, it has been devised that the stroke is determined using this.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately determine a stroke of an internal combustion engine without using a cam angle sensor, and to determine a correlation between the stroke and the actual intake air amount after the stroke is determined. It is an object of the present invention to provide a stroke discriminating method and a stroke discriminating device for an internal combustion engine, which can control the internal combustion engine with high accuracy.
[0008]
[Means for Solving the Problems]
To achieve the above object, a method for determining a stroke of an internal combustion engine according to the present invention detects at least one TDC (top dead center) signal during one cycle of the internal combustion engine and operates the internal combustion engine. The purpose is to detect the lower limit value of the intake pressure pulsation at the time and determine the stroke of the internal combustion engine based on the relationship between the detection timing of the TDC signal and the lower limit value of the intake pressure pulsation.
[0009]
According to the present invention, since the lower limit of the intake pressure pulsation occurs during the compression stroke of the internal combustion engine, the compression stroke can be determined by detecting the lower limit of the intake pressure pulsation during operation of the internal combustion engine. Further, at least one TDC (top dead center) signal is detected during one cycle of the internal combustion engine. Thus, the stroke of the internal combustion engine can be determined from the relationship between the detection timing of the TDC signal and the lower limit value of the intake pressure pulsation. As described above, by detecting the lower limit value of the intake pressure pulsation, the stroke of the internal combustion engine can be accurately determined without using a cam angle sensor.
[0010]
In addition, in the detected value of the intake pressure pulsation, the lower limit value is the intake pressure that best reflects the actual intake air amount. Nevertheless, the control amount of the internal combustion engine does not become an unstable value. Therefore, accurate control of the internal combustion engine having a high correlation with the actual intake air amount can be performed after the stroke determination.
[0011]
In order to achieve the above object, a method for determining a stroke of an internal combustion engine according to the present invention detects at least one TDC (top dead center) signal during one cycle of the internal combustion engine and operates the internal combustion engine. Sometimes, the lower limit value of the intake pressure pulsation is detected, and when the TDC signal is first detected after the lower limit value of the intake pressure pulsation is detected, it is determined that it is the compression top dead center.
[0012]
According to the invention, when the lower limit value of the intake pressure pulsation occurring during the compression stroke of the internal combustion engine is detected, and the TDC signal is first detected after the lower limit value of the intake pressure pulsation is detected, it is determined that the compression top dead center is reached. From the determination, the compression TDC can be accurately determined without using a cam angle sensor.
[0013]
In addition, in the detected value of the intake pressure pulsation, the lower limit value is the intake pressure that best reflects the actual intake air amount. Nevertheless, the control amount of the internal combustion engine does not become an unstable value. Therefore, accurate control of the internal combustion engine having a high correlation with the actual intake air amount can be performed after the stroke determination.
[0014]
In order to achieve the above object, according to a third aspect of the present invention, there is provided a stroke determination device for an internal combustion engine, comprising: signal detection means for detecting at least one TDC (top dead center) signal during one cycle of the internal combustion engine; Intake pressure detecting means for detecting the intake pressure of the engine; lower limit detecting means for detecting a lower limit value of the intake pressure pulsation during operation of the internal combustion engine based on a value detected by the intake pressure detecting means; It is intended to include a stroke discriminating means for discriminating a stroke of the internal combustion engine based on the timing of detecting the value and the timing of detecting the TDC signal by the signal detecting means.
[0015]
According to the configuration of the present invention, at least one TDC (top dead center) signal is detected by the signal detection means during one cycle of the internal combustion engine. Further, the lower limit value detecting means detects the lower limit value of the intake pressure pulsation during the operation of the internal combustion engine based on the value detected by the intake pressure detecting means. This lower limit is detected during the compression stroke of the internal combustion engine. Then, the stroke determination of the internal combustion engine is performed by the stroke determination means based on the detection time of the lower limit value by the lower limit value detection means and the detection time of the TDC signal by the signal detection means. As described above, by detecting the lower limit value of the intake pressure by the lower limit value detecting means, it is possible to accurately determine the stroke of the internal combustion engine without using a cam angle sensor.
[0016]
Further, by setting the lower limit value that best reflects the actual intake air amount as the detected value of the intake air pressure, the control amount of the internal combustion engine does not become an unstable value despite the intake air pressure accompanied by pulsation. Therefore, accurate control of the internal combustion engine having a high correlation with the actual intake air amount can be performed after the stroke determination.
[0017]
According to a fourth aspect of the present invention, there is provided a process for determining a stroke of an internal combustion engine according to the third aspect of the present invention, wherein the lower limit detecting means determines a lower limit of the intake pressure pulsation. When the signal detection means first detects the TDC signal after the detection, it is determined that the TDC signal is determined to be the compression top dead center.
[0018]
According to the configuration of the invention described above, in the operation of the invention described in claim 3, the signal detection means first detects the TDC signal after the lower limit value detection means detects the lower limit value of the intake pressure pulsation by the stroke determination means. At this time, since the compression TDC is determined, the compression TDC can be determined accurately without using a cam angle sensor.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a most preferred embodiment which embodies an internal combustion engine stroke discriminating method, a stroke discriminating device using the discriminating method, and a control device of an internal combustion engine using the stroke discriminating device will be described with reference to the drawings. This will be described in detail.
[0020]
FIG. 1 shows a schematic configuration of an engine system according to the present embodiment. The engine system mounted on the vehicle includes a fuel tank 1 for storing fuel. A fuel pump 2 built in the fuel tank 1 discharges the fuel stored in the tank 1. A fuel injection valve (injector) 4 is provided in a reciprocating single cylinder engine 3 which is an internal combustion engine. The fuel discharged from the fuel pump 2 is supplied to the injector 4 through the fuel passage 5. The supplied fuel is injected into the intake passage 6 by the operation of the injector 4. Air is taken into the intake passage 6 from outside through an air cleaner 7. The air taken into the intake passage 6 and the fuel injected from the injector 4 form a combustible mixture and are sucked into the combustion chamber 8.
[0021]
The intake passage 6 is provided with a throttle valve 9 operated by a predetermined accelerator device (not shown). By opening and closing the throttle valve 9, the amount of air (intake amount) drawn into the combustion chamber 8 from the intake passage 6 is adjusted. A bypass passage 10 is provided in the intake passage 6 so as to bypass the throttle valve 9. The bypass passage 10 is provided with an idle speed control valve (ISC valve) 11. The ISC valve 11 is operated to adjust the idle rotation speed of the engine 3 during idling operation, that is, when the throttle valve 9 is fully closed.
[0022]
The ignition plug 12 provided in the combustion chamber 8 performs a spark operation in response to an ignition signal output from the ignition coil 13. The two parts 12 and 13 constitute an ignition device for igniting the combustible mixture supplied to the combustion chamber 8. The combustible air-fuel mixture sucked into the combustion chamber 8 explodes and burns due to the spark operation of the ignition plug 12. The exhaust gas after combustion is discharged from the combustion chamber 8 to the outside through the exhaust passage 14. The exhaust passage 14 is provided with a three-way catalyst 15 for purifying exhaust gas. With the combustion of the combustible mixture in the combustion chamber 8, the piston 16 moves and the crankshaft 17 rotates, so that the engine 3 obtains a driving force for running the vehicle.
[0023]
The vehicle is provided with an ignition switch 18 for starting the engine 3. The vehicle is provided with an electronic control unit (ECU) 20 that controls various controls of the engine 3. A battery 19 as a vehicle power supply is connected to an ECU 20 via an ignition switch 18. When the ignition switch 18 is turned on, electric power is supplied from the battery 19 to the ECU 20.
[0024]
Various sensors 21, 22, 23, and 24 provided in the engine 3 are for detecting various operating parameters related to the operating state of the engine 3, and are connected to the ECU 20. That is, the intake pressure sensor 21 serving as intake pressure detection means provided in the intake passage 6 detects the intake pressure pm in the intake passage 6 downstream of the throttle valve 9 and outputs an electric signal corresponding to the detected value. . The water temperature sensor 22 provided in 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 rotation speed sensor 23 serving as a rotation speed detection unit and a TDC signal detection unit provided in the engine 3 detects a rotation speed (engine rotation speed) NE of the crankshaft 17 and outputs an electric signal corresponding to the detected value. At the same time, a TDC signal is detected. An oxygen sensor 24 provided in the exhaust passage 14 detects an oxygen concentration (output voltage) Ox in the exhaust gas discharged to the exhaust passage 14 and outputs an electric signal corresponding to the detected value. This oxygen sensor 24 is used to obtain an air-fuel ratio A / F of a combustible mixture supplied to the combustion chamber 8 of the engine 3.
[0025]
In this embodiment, the ECU 20 inputs various signals output from the various sensors 21 to 24 described above. Based on these input signals, the ECU 20 controls the fuel pump 2, the injector 4, the ISC valve 11, the ignition coil 13, and the like to execute intake pressure detection control, fuel injection control, ignition timing control, and the like. Perform a stroke determination. In this embodiment, the ECU 20 constitutes a lower limit value detecting means and a stroke determining means of the present invention.
[0026]
Here, the intake pressure detection control is a control for obtaining a detected value of the intake pressure excluding the influence of the intake pulsation based on the intake pressure pm detected by the intake pressure sensor 21. The fuel injection control is to control the fuel injection amount and the injection timing of the injector 4 according to the operating state of the engine 3. The ignition timing control is to control the ignition timing of each ignition plug 12 by controlling the ignition coil 13 according to the operating state of the engine 3.
[0027]
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 formed by connecting a CPU, a ROM, a RAM, a backup RAM, an external input circuit, an external output circuit, and the like via a bus. The ROM stores a predetermined control program relating to various controls of the engine 3 in advance. The RAM temporarily stores the calculation results of the CPU. The backup RAM stores data stored in advance. The CPU executes the above-described various controls and the like according to a predetermined control program based on detection signals of the various sensors 21 to 24 input via the input circuit.
[0028]
Next, among the various controls executed by the ECU 20, the processing content for the intake pressure detection control will be described. During this process, the lower limit value of the intake pressure is detected. FIG. 2 is a flowchart showing a program of intake pressure detection (lower limit value pmlo detection) control. The ECU 20 periodically executes the routine shown in FIG. 2 every predetermined period. In this embodiment, this routine is executed at a cycle of “1 ms”.
[0029]
First, in step 100, the ECU 20 reads the current AD value pmad for the intake pressure pm detected by the intake pressure sensor 21.
[0030]
Next, in step 101, the ECU 20 determines whether or not the current AD value pmad is larger than the previous AD value pmado. If the result of this determination is affirmative, it is determined that the intake pressure pm has increased, and in step 102, the ECU 20 sets the present pressure increase flag XPMUP to "1".
[0031]
Next, in step 103, the ECU 20 determines whether or not the previous pressure increase flag XPMUPO is “0”. If the determination result is negative, the ECU 20 shifts the processing to step 107 because the intake pressure pm is increasing following the previous time. If the determination result is affirmative, the process proceeds to step 104 on the assumption that the intake pressure pm has changed from decreasing to increasing.
[0032]
In step 104, the ECU 20 determines whether or not the previous AD value pmado is equal to or less than the upper limit value pmhi of the AD value pmad. If the result of this determination is negative, the ECU 20 proceeds to step 107, assuming that the intake pressure pm has decreased due to the intake pulsation. If the determination result is affirmative, in step 105, the ECU 20 sets the previous AD value pmado as the lower limit value pmlo of the AD value pmad. Then, in step 105a, the ECU 20 turns on the detection flag of the lower limit value pmlo. Thus, the lower limit value pmlo is detected.
[0033]
Then, in step 106, the ECU 20 sets the lower limit value pmlo as the intake pressure PM to be finally obtained.
[0034]
On the other hand, if the determination result in step 101 is negative, the ECU 20 sets the present pressure increase flag XPMUP to “0” in step 111 assuming that the intake pressure pm is decreasing.
[0035]
Next, at step 112, the ECU 20 determines whether or not the previous pressure increase flag XPMUPO is “0”. If the result of this determination is affirmative, the ECU 20 proceeds to step 107, assuming that the intake pressure pm is decreasing following the previous time. If the determination result is negative, the ECU 20 sets the previous AD value pmado as the upper limit value pmhi of the AD value pmad in step 113, assuming that the intake pressure pm has changed from rising to falling.
[0036]
Then, after shifting from steps 103, 104, 106, 112, and 113, in step 107, the ECU 20 sets the current AD value pmad as the previous AD value pmado.
[0037]
Next, in step 108, the ECU 20 determines whether or not the current pressure increase flag is “1”. If the determination result is affirmative, in step 109, the ECU 20 sets the previous pressure increase flag XPMUPO to “1”, and temporarily ends the subsequent processing. If the determination result is negative, in step 110, the ECU 20 sets the previous pressure increase flag XPMUPO to “0” and temporarily ends the subsequent processing.
[0038]
That is, in the above routine, the lower limit value pmlo of the pulsation of the intake pressure pm is detected during the operation of the engine 3, and the lower limit value pmlo is used as the final intake pressure PM as the detected value of the intake pressure pm. For this purpose, as shown in FIG. 3, for the intake pressure pm accompanied by pulsation, the previous AD value pmado continuously sampled and the current AD value pmad are compared to determine whether the intake pressure pm has decreased or increased. And at the same time, determine whether the transition from ascending to descending or from descending to ascending. Then, the previous AD value pmado at the time of the transition from ascending to descending is set as the upper limit value pmhi, the previous AD value pmado at the time of the transition from the descending to ascending is set as the lower limit value pmlo, and the lower limit value pmlo is set as the final value. It is set as a value of a typical intake pressure PM.
[0039]
In the engine system according to this embodiment, stroke determination is performed using the intake pressure PM detected as described above. Then, the processing content of this stroke determination will be described next. In the engine system of this embodiment, in order to detect a TDC signal, as shown in FIG. 4, TDC is detected based on signals from five teeth 25 attached to the crankshaft 17. These teeth 25 are attached one by one at every 90 ° CA, and the remaining one tooth is attached at a position shifted (delayed) by 30 ° CA from any one of the four teeth.
[0040]
FIG. 5 is a flowchart showing a program for stroke determination when such TDC determination is performed. FIG. 6 shows changes in various parameters in the engine system according to the present embodiment. FIG. 6 shows the rotation signal, the intake pressure, the intake pressure lower limit detection flag, and the crank no. Are shown over time. Note that the ECU 20 periodically executes the routine shown in FIG. 5 every predetermined period.
[0041]
First, in step 150, the ECU 20 determines whether the TDC determination has been completed. If the determination result is affirmative, the ECU 20 shifts the processing to step 151 since the TDC determination has been completed. If the result of the determination is negative, the ECU 20 proceeds to step 157 because the determination of TDC has not been completed, and executes a separate TDC determination routine to determine TDC.
[0042]
In step 151, the ECU 20 determines whether or not this time is an interruption of the TDC signal. If this determination result is affirmative, the process proceeds to step 152 because a TDC signal has been detected this time. More specifically, as shown in FIG. 6, the TDC signal is detected at 0 ° CA and 360 ° CA. At this time, the ECU 20 makes a positive determination in step 151. On the other hand, if the result of the determination is negative, the process proceeds to step 158 since no TDC signal has been detected this time.
[0043]
Then, in step 152, the ECU 20 determines whether or not the detection flag of the intake pressure lower limit value pmlo is on. If this determination result is affirmative, in step 153, the ECU 20 turns off the detection flag of the lower limit value pmlo. Further, in step 154, the crank No. Is set to “0”. Then, in step 155, the ECU 20 determines that the current time is the compression TDC, turns on the stroke determination flag, and temporarily ends the subsequent processing. Here, the intake pressure lower limit value pmlo is detected in the compression stroke, as shown in FIG. 6, and thereafter, the detection flag of the lower limit value pmlo is turned on. In this state, when a TDC signal is detected, it can be determined that the time is a compressed TDC. Therefore, by the above processing, the ECU 20 can accurately determine the compression TDC.
[0044]
On the other hand, if the determination result is negative, the ECU 20 determines in step 156 that the crank no. Is set to “4”. Then, in step 155, the ECU 20 determines that the current time is the exhaust TDC, turns on the stroke determination flag, and temporarily ends the subsequent processing. Here, as shown in FIG. 6, the intake pressure lower limit value pmlo is detected in the compression stroke, and the detection flag of the lower limit value pmlo is turned on. In the case of the compression TDC, the detection flag of the lower limit value pmlo is turned off. For this reason, if the TDC signal is detected while the detection flag of the lower limit value pmlo is off, it can be determined that the time is the exhaust TDC. Therefore, by the above processing, the ECU 20 can accurately determine the exhaust TDC.
[0045]
In step 158, the ECU 20 determines whether or not this time is an interruption of the +1 tooth signal. If the result of this determination is affirmative, the processing shifts to step 152 since the +1 tooth signal has been detected, and the crank no. To “+1”. If the result of the determination is negative, it is assumed that there has been no signal interruption this time, and the subsequent processing is temporarily terminated.
[0046]
Thus, in the engine system according to the embodiment, the stroke can be determined based on the detection flag of the lower limit value pmlo of the intake pressure and the TDC signal. Therefore, the control of the injection system and the ignition system can be performed by one injection and one ignition / 2 rotations (stroke), so that the load on the ignition system is reduced and the durability is improved. Also decrease. In particular, in a vehicle with a small battery, such as a two-wheeled vehicle, the fuel efficiency at which the electric load becomes large also deteriorates. Therefore, the fuel efficiency can be improved by reducing the electric load. Further, a cam angle sensor, which is conventionally required for stroke determination, is not required. This makes it possible to reduce the cost, size, and weight of the engine system.
[0047]
Further, since the compression TDC and the exhaust TDC can be accurately determined (stroke determination), the control of the fuel injection timing can be performed with high accuracy. That is, different fuel injection timings can be set in the warm-up state or the operation state. Specifically, during cold start and when the accelerator is fully open (WOT), control is performed such that fuel is injected when the intake valve is open, and during normal operation after warming up, the fuel is injected when the intake valve is closed. It is possible to control to inject fuel. The reason for controlling the fuel injection timing in this way is that the demand for the fuel injection timing is different depending on the warm-up state or the operating state of the engine.
[0048]
By controlling the fuel injection timing as described above, at low temperatures, the fuel is injected when the intake valve is open, so that the fuel is synchronized with the flow of the intake air. At the same time, dropping of fuel adhering to the wall surface is reduced. Therefore, the combustion state is improved, and the HC concentration in the exhaust gas decreases as shown in FIG. As a result, low-temperature startability can be improved, and fuel efficiency at low temperatures can be improved.
[0049]
On the other hand, during normal operation after warm-up, fuel is injected when the intake valve is closed, as opposed to at low temperatures. During normal operation after warming-up, the engine body is sufficiently warmed up, so that injecting fuel at this timing will receive more heat from the engine, thus improving atomization (vaporization) of the fuel. As a result, combustion is improved, and the HC concentration in the exhaust gas can be reduced as shown in FIG.
[0050]
In addition, when the accelerator is fully opened (WOT), fuel is injected when the intake valve is open, so that the air density increases due to latent heat of vaporization of the fuel injected into the flow of the intake air. For this reason, the charging efficiency of the engine is improved. Thereby, as shown in FIG. 7, the shaft torque (output) can be improved, and drivability and fuel efficiency can be improved.
[0051]
In the engine system according to this embodiment, the fuel injection amount control is performed using the intake pressure PM detected as described above. Therefore, next, the processing content of the fuel injection amount control will be described. FIG. 8 is a flowchart showing a fuel injection amount control program. The ECU 20 periodically executes the routine shown in FIG. 8 every predetermined period.
[0052]
First, in step 200, the ECU 20 reads the value of the engine speed NE based on the value detected by the speed sensor 23.
[0053]
In step 210, the ECU 20 reads the final value of the intake pressure PM. That is, the lower limit pmlo of the pulsating intake pressure pm is read as the value of the intake pressure PM. The reading process in step 210 is performed by interrupting the above-described routine of FIG.
[0054]
In step 220, the ECU 20 calculates the basic fuel injection amount TAUBSE based on the read value of the engine speed NE and the value of the intake pressure PM. The ECU 20 calculates the basic fuel injection amount TAUBSE by referring to predetermined function data (injection amount map). In this function data, the amount of intake air taken into the combustion chamber 8 of the engine 3 is determined from the value of the intake pressure PM and the value of the engine speed NE, and the basic fuel injection amount TAUBSE according to the intake amount is determined. It has become.
[0055]
In step 230, the ECU 20 reads the value of the cooling water temperature THW based on the value detected by the water temperature sensor 22. Then, in step 240, the ECU 20 calculates a warm-up correction coefficient KTHW for correcting the basic fuel injection amount TAUBSE according to the warm-up state of the engine 3 based on the read value of the coolant temperature THW.
[0056]
In step 250, the ECU 20 reads the value of the air-fuel ratio correction coefficient FAF for correcting the air-fuel ratio A / F of the combustible mixture of air and fuel supplied to the combustion chamber 8. The air-fuel ratio correction coefficient FAF is calculated by a separate routine based on the value of the oxygen concentration Ox read from the value detected by the oxygen sensor 24.
[0057]
In step 260, the ECU 20 calculates the value of the final fuel injection amount TAU by correcting the basic fuel injection amount TAUBSE calculated as described above based on the warm-up correction coefficient KTHW, the air-fuel ratio correction coefficient FAF, and the like. .
[0058]
Thereafter, in step 270, the ECU 20 controls the amount of fuel injected from the injector 4 by controlling the injector 4 based on the value of the calculated final fuel injection amount TAU.
[0059]
In the engine system of this embodiment, the ignition timing control is performed using the intake pressure PM detected as described above. Therefore, the processing content of the ignition timing control will be described. FIG. 9 is a flowchart showing the ignition timing control program. The ECU 20 periodically executes the routine shown in FIG. 9 every predetermined period.
[0060]
First, in step 300, the ECU 20 reads the value of the engine speed NE based on the value detected by the speed sensor 23.
[0061]
In step 310, the ECU 20 reads the final value of the intake pressure PM. That is, the lower limit pmlo of the pulsating intake pressure pm is read as the value of the intake pressure PM. The reading process of step 310 is performed by interrupting the above-described routine of FIG.
[0062]
In step 320, the ECU 20 calculates the basic ignition timing ITBSE based on the read value of the engine speed NE and the value of the intake pressure PM. The ECU 20 calculates the basic ignition timing ITBSE by referring to predetermined function data (ignition timing map). In this function data, the amount of intake air taken into the combustion chamber 8 of the engine 3 is determined from the value of the intake pressure PM and the value of the engine speed NE, and the basic ignition timing ITBSE according to the amount of intake air is determined. It has become.
[0063]
In step 330, the ECU 20 reads the value of the cooling water temperature THW based on the value detected by the water temperature sensor 22. Then, in step 340, the ECU 20 calculates a warm-up correction coefficient K1 for correcting the basic ignition timing ITBSE according to the warm-up state of the engine 3 based on the read value of the coolant temperature THW.
[0064]
In step 350, the ECU 20 calculates the value of the final ignition timing IT by correcting the basic ignition timing ITBSE calculated as described above based on the warm-up correction coefficient K1 and the like.
[0065]
Thereafter, in step 360, the ECU 20 controls the ignition coil 13 based on the calculated value of the final ignition timing IT, thereby controlling the ignition timing of the ignition plug 12.
[0066]
As described above, in the engine system of the present embodiment, when the engine 3 is operating, the pulsation of the intake air occurs in the intake passage 6, and the intake pressure pm detected by the intake pressure sensor 21 also accompanies the pulsation. . For this reason, if the intake pressure pm accompanied by pulsation is directly used as one of the operation parameters for executing various controls of the engine 3, the various controls become unstable.
[0067]
Here, the present applicant has found that, in the detected value of the intake pressure pm accompanied by the pulsation, the lower limit pmlo is the intake pressure that best reflects the intake air amount actually sucked into the combustion chamber 8, and the lower limit pmlo is the engine Was detected during the compression stroke. Therefore, in this engine system, the lower limit value pmlo is detected for the intake pressure pulsation, that is, the pulsating intake pressure pm, and the lower limit value pmlo is used as the final detected value of the intake pressure PM. The engine stroke is determined using the detection timing (detection flag). Accordingly, an appropriate value and behavior correlated with the intake air amount can be obtained as the final intake pressure PM regardless of the intake pressure pm accompanied by pulsation, and the stroke can be accurately determined. As a result, various types of engine control such as fuel injection amount control, fuel injection timing control, and ignition timing control can be performed with very high accuracy.
[0068]
In the above-described embodiment, the five teeth 25 (90 ° CA + 1 teeth) are attached to the crankshaft 17. However, if only one tooth 25 is attached to the crankshaft 17 as shown in FIG. Thus, the stroke of the engine 3 can be determined. That is, according to the present invention, the stroke of the engine can be determined by attaching at least one tooth to the crankshaft. Therefore, the processing content of stroke determination when only one tooth is attached to the crankshaft will be briefly described.
[0069]
FIG. 11 is a flowchart showing a stroke determination program in the engine system according to the other embodiment. FIG. 12 shows changes in various parameters in the engine system according to the other embodiment. FIG. 12 shows the rotation signal, the intake pressure, and the intake pressure lower limit detection flag over time. Note that the ECU 20 periodically executes the routine shown in FIG. 11 every predetermined period.
[0070]
The ECU 20 determines whether or not the detection flag of the intake pressure lower limit value pmlo is turned on. If the determination result is affirmative, the ECU 20 turns off the detection flag of the lower limit value pmlo and determines that the current time is the compression TDC. Here, the intake pressure lower limit value pmlo is detected in the compression stroke as shown in FIG. 12, and thereafter, the detection flag of the lower limit value pmlo is turned on. In this state, when a TDC signal is detected, it can be determined that the time is a compressed TDC. Therefore, by the above processing, the ECU 20 can accurately determine the compression TDC.
[0071]
On the other hand, if the determination result is negative, the ECU 20 determines that the current time is the exhaust TDC because the intake pressure is not at the lower limit. Here, as shown in FIG. 12, the lower limit value of the intake pressure pmlo is detected in the compression stroke, and the detection flag of the lower limit value pmlo is turned on. In the case of the compression TDC, the detection flag of the lower limit value pmlo is turned off. For this reason, if the TDC signal is detected while the detection flag of the lower limit value pmlo is off, it can be determined that the time is the exhaust TDC. Therefore, by the above processing, the ECU 20 can accurately determine the exhaust TDC.
[0072]
As described above, even when only one tooth is attached to the crankshaft 17, it is possible to accurately determine the compression TDC and the exhaust TDC by using the detection flag of the lower limit value pmlo. The same effect as in the embodiment can be obtained.
[0073]
It should be noted that the above-described embodiment is merely an example, and does not limit the present invention in any way. Needless to say, various improvements and modifications can be made without departing from the gist of the invention. For example, it can be carried out as follows.
[0074]
(1) In the above-described embodiment, the stroke determination method, the stroke determination device, and the like of the present invention are embodied in an engine system including the single-cylinder engine 3. However, the two-cylinder engine, the three-cylinder engine, or the engine having more cylinders The present invention can also be embodied in an engine system including
[0075]
(2) In the above embodiment, five teeth (90 ° CA + 1 tooth) or only one tooth are attached to the crankshaft 17 in order to detect TDC. The number of teeth may be four, four, or six or more. By installing more teeth, it is possible to control the engine with high accuracy, but this is disadvantageous in terms of cost. Therefore, the optimum number of teeth may be attached in consideration of the required control accuracy and cost. In the case of two teeth, TDC cannot be distinguished if it is mounted at a symmetrical position, so it is necessary to mount it at a position other than the symmetrical position.
[0076]
(3) In the embodiment, the raw lower limit value pmlo and the upper limit value pmhi of the pulsating AD value pmad are detected in the flowchart of FIG. On the other hand, the difference between the upper limit pmhi and the lower limit pmlo is guarded in order to prevent the upper limit pmhi and the lower limit pmlo from being accurately taken in due to the effect of a blowback from the combustion chamber, such as when the engine is fully loaded. By setting the values and detecting the upper limit value pmhi and the lower limit value pmlo obtained in the range of the guard value, erroneous detection of the intake pressure PM may be prevented.
[0077]
【The invention's effect】
According to the first aspect of the present invention, it is possible to determine the stroke of the internal combustion engine without using a cam angle sensor, and at the same time, has excellent stability and responsiveness, and has a high correlation with the actual intake air amount. Accurate control of the internal combustion engine can be executed.
[0078]
According to the second aspect of the present invention, it is possible to accurately determine the compression top dead center of the internal combustion engine without using a cam angle sensor. Thus, accurate control of the internal combustion engine with high correlation can be executed.
[0079]
According to the third aspect of the present invention, it is possible to determine the stroke of the internal combustion engine without using a cam angle sensor, and at the same time, it is excellent in stability and responsiveness, and has a correlation with an actual intake air amount. And accurate and accurate control of the internal combustion engine can be executed.
[0080]
According to the configuration of the invention described in claim 4, the compression top dead center of the internal combustion engine can be accurately determined without using a cam angle sensor. Accurate control of the internal combustion engine having a high correlation with the quantity can be executed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an engine system according to an embodiment.
FIG. 2 is a flowchart showing a program of intake pressure (lower limit) detection control.
FIG. 3 is an explanatory diagram showing a pulsating intake pressure, its AD value, and the like.
FIG. 4 is an explanatory view showing a mounting position of a tooth to a crankshaft.
FIG. 5 is a flowchart showing a program for stroke determination.
FIG. 6 is a time chart showing the behavior of various parameters in the engine system of the embodiment.
FIG. 7 is an explanatory diagram showing an optimal fuel injection timing.
FIG. 8 is a flowchart showing a fuel injection control program.
FIG. 9 is a flowchart showing a program for ignition timing control.
FIG. 10 is an explanatory diagram showing attachment positions of teeth to a crankshaft in an engine system according to another embodiment.
FIG. 11 is a flowchart illustrating a stroke determination program in an engine system according to another embodiment.
FIG. 12 is a time chart showing the behavior of various parameters in an engine system according to another embodiment.
[Explanation of symbols]
3 Engine
6 Intake passage
17 Crankshaft
20 ECU (lower limit detection means, stroke determination means)
21 Intake pressure sensor (intake pressure detection means)
23 Rotation speed sensor (signal detection means)

Claims (4)

Detecting at least one TDC (top dead center) signal during one cycle of the internal combustion engine, and detecting a lower limit of intake pressure pulsation during operation of the internal combustion engine;
A stroke discrimination method for an internal combustion engine, wherein the stroke discrimination of the internal combustion engine is performed based on a relationship between a detection timing of the TDC signal and a lower limit value of the intake pressure pulsation. Detecting at least one TDC (top dead center) signal during one cycle of the internal combustion engine, and detecting a lower limit value of intake pressure pulsation during operation of the internal combustion engine;
A method for determining a stroke of an internal combustion engine, comprising: determining a compression top dead center when the TDC signal is first detected after detecting a lower limit value of the intake pressure pulsation. Signal detection means for detecting at least one TDC (top dead center) signal during one cycle of the internal combustion engine;
Intake pressure detecting means for detecting the intake pressure of the internal combustion engine,
Lower limit value detecting means for detecting the lower limit value of the intake pressure pulsation during operation of the internal combustion engine based on the detection value by the intake pressure detecting means,
Stroke determination means for performing a stroke determination of the internal combustion engine based on the detection time of the lower limit value by the lower limit value detection means and the detection time of the TDC signal by the signal detection means;
A stroke determination device for an internal combustion engine, comprising: The stroke determination device for an internal combustion engine according to claim 3,
The stroke discriminating means, when the signal detecting means first detects the TDC signal after the lower limit value detecting means detects the lower limit value of the intake pressure pulsation, judges that the TDC signal is the compression top dead center. Of determining the stroke of an internal combustion engine.

Images