JP3965577B2 - Start control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a start control device for an internal combustion engine that rotationally drives a crankshaft by injecting and igniting fuel into a cylinder in an expansion stroke or a compression stroke when the internal combustion engine (engine) is started.
[0002]
[Prior art]
In recent years, some engines mounted on vehicles employ an engine automatic stop / start device (so-called idling stop device) for the purpose of reducing fuel consumption, reducing exhaust emissions, and reducing noise. This automatic engine stop / start device, for example, automatically stops the engine when the driver stops the vehicle, and then the driver tries to start the vehicle (for example, accelerator pedal depression operation). When starting, the starter is energized and the engine is automatically restarted. For this reason, when driving in an urban area where the frequency of stopping is high, the number of times the starter is driven increases, and the load applied to the starter and the battery increases.
[0003]
As a countermeasure, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2002-39038), when the engine is automatically started, fuel is injected into the cylinder in the expansion stroke and ignited to generate expansion stroke combustion. It has been proposed to perform “starterless start” in which the engine is started without using a starter by rotationally driving (cranking) the crankshaft with the combustion pressure of the expansion stroke combustion.
[0004]
In the technique of Patent Document 1, a stopper is provided for forcibly stopping the rotation of the crankshaft at a position where the first cylinder is at ATDC 10 ° C. to 140 ° C. in the expansion stroke when the engine is stopped. Is always limited to a position where the first cylinder is at ATDC 10 ° C. to 140 ° C. in the expansion stroke, so that at the time of restart, fuel is always injected and ignited from the first cylinder to generate expansion stroke combustion. ing.
[0005]
And, at the time of restart, detection of the crank angle reference position (determination of a specific cylinder) after the engine starts to rotate by the first expansion stroke combustion is shown in, for example, Japanese Patent Laid-Open No. 8-50035. As described above, the determination is made by determining the pulse interval of the crank angle pulse signal output from the crank angle sensor. This crank angle sensor generates crank angle pulse signals at regular intervals according to engine rotation in the crank angle region except for a predetermined crank angle reference position, and generates crank angle pulse signals at irregular intervals at the crank angle reference position. Is configured to do. The engine control computer determines whether the crank angle pulse signal output from the crank angle sensor has an equal interval or an unequal interval, thereby determining the position at which the unequal interval crank angle pulse signal is generated. It is detected as an angle reference position, crank angle pulse signals at equal intervals are counted from this crank angle reference position, and the crank angle is detected from the count value.
[0006]
[Patent Document 1]
JP 2002-39038 A (pages 3 to 5 etc.)
[Patent Document 2]
JP-A-8-261053 (pages 5 to 6 etc.)
[0007]
[Problems to be solved by the invention]
By the way, in the start by the starter, the starter works to reduce the engine rotation fluctuation by absorbing the engine rotation fluctuation at the initial stage of the start, but as in the above-mentioned Patent Document 1, in the starterless start that starts the engine by the combustion pressure, Since the effect of suppressing the engine rotation fluctuation by the starter cannot be expected, the engine rotation fluctuation due to the initial combustion tends to increase as shown in FIG.
[0008]
Since the pulse interval of the crank angle pulse signal output from the crank angle sensor described above varies depending on the engine rotation speed, it becomes difficult to distinguish whether the pulse interval is an equal interval or an unequal interval when the engine rotation fluctuation increases. Accordingly, immediately after the engine starts to rotate due to the first expansion stroke combustion, immediately after determining the crank angle reference position by determining the pulse interval of the crank angle pulse signal, the crank angle is caused by the large engine rotation fluctuation due to the initial combustion described above. There is a possibility that the crank angle reference position is erroneously detected by misjudging equal intervals and unequal intervals of the pulse signal. As a result, if the crank angle reference position is erroneously detected, the wrong cylinder is discriminated, so that the wrong cylinder is injected and ignited, resulting in a problem that the engine cannot be started.
[0009]
The present invention has been made in view of such circumstances, and the object of the present invention is therefore to provide an engine in the initial stage of startup in a system in which fuel is injected and ignited into a cylinder in an expansion stroke or a compression stroke at the time of startup to start with combustion pressure. An object of the present invention is to provide a start control device for an internal combustion engine that can prevent erroneous injection and erroneous ignition due to erroneous detection of the crank angle reference position at a time when the rotational fluctuation is large, and that can improve startability by combustion pressure.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, a start control device for an internal combustion engine according to claim 1 of the present invention determines whether the pulse intervals of the crank angle pulse signal output from the crank angle pulse signal generating means are equal intervals or unequal intervals. In a system that detects a position at which crank angle pulse signals at unequal intervals are generated as a crank angle reference position, counts crank angle pulse signals at equal intervals from the crank angle reference position, and performs cylinder discrimination based on the counted number A start control means for performing start control for injecting fuel into a cylinder in an expansion stroke or a compression stroke when starting the internal combustion engine, and a stop position detecting means for detecting a stop position of the internal combustion engine; Until the predetermined period of time elapses from the start of control, detection of the crank angle reference position by the crank angle pulse signal at unequal intervals is prohibited, and the stop position detection Executing the cylinder discrimination to injection control and / or ignition control in based on the detected stop positionThe first feature is that the compression top dead center is detected based on the engine rotation fluctuation from the start of the start control until the crank angle reference position is detected, and ignition is performed after the detection of the compression top dead center. This is a second feature.
[0011]
In this configuration, since the detection of the crank angle reference position by the crank angle pulse signal at irregular intervals is prohibited until a predetermined period when the engine rotation fluctuation becomes somewhat small from the start of the start control, It is possible to prevent erroneous detection of the crank angle reference position at a large time. During this crank angle reference position detection prohibition period, the cylinder is discriminated based on the stop position detected by the stop position detecting means. Therefore, it is possible to discriminate the cylinder without any error, prevent erroneous injection and erroneous ignition, and improve the startability by the combustion pressure.
[0012]
In this case, as a method for prohibiting the detection of the crank angle reference position, the process of determining whether the pulse interval of the crank angle pulse signal is an equal interval or an unequal interval may be omitted. By changing the determination value for determining whether the pulse interval of the crank angle pulse signal is equal or unequal until the predetermined period elapses from the start of the start control to a determination value that makes the unequal interval indistinguishable The detection of the crank angle reference position may be prohibited. In this way, the crank angle reference position can be detected without stopping the process of determining whether the pulse angle of the crank angle pulse signal is equal or unequal during the crank angle reference position detection prohibition period. Can be banned.
[0013]
According to a third aspect of the present invention, the crank angle reference position detection prohibition period (predetermined period) may be set to a period until the crankshaft rotation angle reaches a predetermined angle from the start of the start control. . The period during which the engine rotation fluctuation at the start of the engine is large can be understood empirically and experimentally. Therefore, the detection prohibition period of the crank angle reference position can be set according to the rotation angle of the crankshaft from the start of the start control. The rotation angle of the crankshaft from the start of the start control may be detected by the count number of the crank angle pulse signal from the start of the start control.
[0014]
Further, in consideration of the fact that the fluctuation of the engine speed becomes large and the crank angle reference position is likely to be erroneously detected when the engine speed is low at the initial stage of startup, the crank angle reference position detection prohibited period as in claim 4. May be set to a period until the engine speed reaches a predetermined value. In this way, even if the engine rotation speed increase at the time of starting changes due to the starting conditions, fuel properties, changes over time, manufacturing variations, etc. of the internal combustion engine, the detection prohibition period of the crank angle reference position is appropriately set accordingly. Can be set to
[0015]
Alternatively, as described in claim 5, the crank angle reference position detection prohibition period may be set to a period until the engine rotation fluctuation becomes a predetermined value or less. Even if it does in this way, the effect similar to the invention concerning the said Claim 4 can be acquired.
[0016]
By the way, when starting by injecting and igniting a cylinder in the compression stroke, if the ignition is ignited earlier than the compression top dead center, the internal combustion engine cannot be reversed and started, so the ignition timing must be delayed from the compression top dead center However, if the ignition timing is too late, the torque necessary for starting cannot be obtained and the starting cannot be performed. Therefore, it is desirable to set the ignition timing at a time after the compression top dead center, but the stop position detected by the stop position detecting means is position information having a certain amount of width (error). Even if the compression top dead center is detected based on the number of counts of the crank angle pulse signal from the start of the start based on the stop position detected by the detection means, the compression top dead center cannot be accurately detected.
[0017]
  With this in mind, the claims1As described above, from the start of the start control until the crank angle reference position is detected, the compression top dead center is detected based on the engine rotation fluctuation, and the ignition is executed after the detection of the compression top dead center. good. When the engine speed is low at the start of the engine, the piston speed of the cylinder in the compression stroke rises, and the engine speed decreases as the cylinder pressure increases. When the compression top dead center is exceeded, the cylinder pressure decreases and the engine speed decreases. Therefore, the engine rotational speed reverses from a decrease to an increase at the compression top dead center. Therefore, if the engine rotation speed is monitored and the position where the engine rotation speed is reversed from the decrease to the increase is detected as the compression top dead center, the compression top dead center can be relatively accurately detected without detecting the crank angle reference position. It can be detected well. As a result, ignition can be executed at an appropriate timing after detection of compression top dead center, and the engine can be reliably started.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
<< Embodiment (1) >>
Hereinafter, an embodiment (1) of the present invention will be described with reference to FIGS. First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an in-cylinder internal combustion engine, and an air flow meter 14 for detecting the intake air amount is provided downstream of the air cleaner 13. . A throttle valve 16 driven by a motor 15 such as a DC motor is provided on the downstream side of the air flow meter 14, and an opening degree (throttle opening degree) of the throttle valve 16 is detected by a throttle opening degree sensor 17.
[0019]
A surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 that introduces air into each cylinder of the engine 11, and controls the in-cylinder airflow strength (swirl flow strength and tumble flow strength) in the intake manifold 20 of each cylinder. An airflow control valve 31 is provided.
[0020]
A fuel injection valve 21 that directly injects fuel into the cylinder is attached to an upper portion of each cylinder of the engine 11. A spark plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by the spark discharge of each spark plug 22.
[0021]
The cylinder block of the engine 11 is provided with a knock sensor 32 that detects knocking, a cooling water temperature sensor 23 that detects the cooling water temperature, and a crank angle sensor 24 (crank angle pulse signal generation means) that detects the crank angle of the engine 11. It has been. The crank angle sensor 24 is disposed so as to face the outer periphery of the signal rotor 37 fitted to the crankshaft of the engine 11, and teeth 37 a are formed on the outer periphery of the signal rotor 37 for each predetermined crank angle. At a specific crank angle position (crank angle reference position) on the outer periphery of the signal rotor 37, a missing tooth portion lacking 1 to 3 teeth 37a is formed. As a result, in the crank angle region other than the tooth missing portion with the rotation of the engine 11, crank angle pulse signals at equal intervals are output from the crank angle sensor 24 at every predetermined crank angle, and the tooth missing portion (crank angle reference position). Then, crank angle pulse signals with unequal intervals that increase the pulse interval are output (see FIG. 5).
[0022]
On the other hand, the exhaust pipe 25 of the engine 11 is provided with an upstream catalyst 26 and a downstream catalyst 27 for purifying the exhaust gas, and the air-fuel ratio or rich / lean of the exhaust gas is detected on the upstream side of the upstream catalyst 26. An exhaust gas sensor 28 (air-fuel ratio sensor, oxygen sensor, etc.) is provided. Further, a part of the exhaust gas is recirculated to the intake side between the downstream side of the upstream catalyst 26 in the exhaust pipe 25 and the surge tank 18 on the downstream side of the throttle valve 16 in the intake pipe 12. An EGR pipe 33 is connected, and an EGR valve 34 for controlling the exhaust gas recirculation amount (EGR amount) is provided in the middle of the EGR pipe 33.
[0023]
Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various control programs stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 21 and the fuel are controlled according to the engine operating state. The injection timing, the ignition timing of the spark plug 22 and the like are controlled.
[0024]
The ECU 30 determines whether the pulse interval of the crank angle pulse signal output from the crank angle sensor 24 is equal or unequal, and determines the position (missing tooth portion) where the unequal interval crank angle pulse signal is generated. The crank angle is detected as the crank angle reference position, and crank angle pulse signals at equal intervals from the crank angle reference position are counted, and the crank angle is detected based on the counted number to determine the cylinder. The function of the ECU 30 corresponds to crank angle detection means in the claims. Note that the ECU 30 detects the engine speed from the generation frequency of equally spaced crank angle pulse signals.
[0025]
The ECU 30 also has an automatic engine stop / auto start function. When the driver stops the vehicle and a predetermined automatic stop condition is satisfied, fuel cut and ignition cut are executed to automatically start the engine 11. While stopping, the engine stop position at that time is detected and stored in the memory of the ECU 30. This engine stop position detection method is, for example, a stop position detection technique described in Japanese Patent No. 3186524, Japanese Patent Application Laid-Open No. 2002-39038, Japanese Patent Application Laid-Open No. 60-240875, Japanese Patent Application Laid-Open No. 11-107823, and the like. Can be used. The engine stop position detection function of the ECU 30 corresponds to stop position detection means in the claims.
[0026]
The ECU 30 uses the engine stop position stored in the memory as a reference when a predetermined automatic start condition is satisfied during the automatic stop of the engine 11 (when the driver performs an operation to start the vehicle). The cylinder is discriminated, fuel is injected into the cylinder in the expansion stroke or compression stroke, and ignition is performed after detection of compression top dead center to generate combustion, and the crankshaft is driven to rotate by this combustion pressure (cranking) As a result, a “starterless start” is performed in which the engine 11 is started without using a starter (not shown). The function of the ECU 30 corresponds to start control means in the claims.
[0027]
By the way, in the starterless start in which the engine is started with the combustion pressure, since the effect of suppressing the engine rotation fluctuation by the starter cannot be expected, the engine rotation fluctuation due to the initial combustion tends to increase as shown in FIG. Since the pulse interval of the crank angle pulse signal output from the crank angle sensor 24 varies depending on the engine speed (see FIG. 5), it is distinguished whether the pulse interval is equal or unequal when the engine fluctuation increases. It becomes difficult. Therefore, immediately after the engine 11 starts to rotate due to the first combustion, if the pulse interval of the crank angle pulse signal is immediately determined to detect the crank angle reference position, the crank angle pulse is caused by the large engine rotation fluctuation due to the initial combustion described above. There is a possibility that the crank angle reference position is erroneously detected by erroneously determining equal intervals and unequal intervals of signals. As a result, if the crank angle reference position is erroneously detected, the wrong cylinder is discriminated, so that the wrong cylinder is injected and ignited, resulting in a problem that the engine cannot be started.
[0028]
Therefore, the ECU 30 executes a crank angle reference position detection possibility determination routine shown in FIG. 3 described later to perform a predetermined period (for example, 180 ° C. A) in which erroneous detection of the crank angle reference position may occur from the start of the start control. ) Is prohibited until the crank angle reference position is detected based on the crank angle pulse signal at unequal intervals, thereby preventing erroneous detection of the crank angle reference position and using the engine stop position stored in the memory as a reference. Thus, the cylinder is discriminated and the fuel is injected into the cylinder in the expansion stroke or the compression stroke (see FIG. 6).
[0029]
By the way, in the case of starting by injecting and igniting a cylinder in the compression stroke, if the engine 11 is ignited earlier than the compression top dead center, the engine 11 cannot be reversed and started. However, if the ignition timing is too late, the torque necessary for starting cannot be obtained and the starting cannot be performed. Therefore, it is desirable to set the ignition timing at a time that is not late after compression top dead center. However, since the engine stop position detected at the time of automatic stop is position information having a certain width (error), Even if the compression top dead center is detected based on the count number of the crank angle pulse signal from the start of the start based on the detected stop position, the compression top dead center cannot be accurately detected.
[0030]
Therefore, the ECU 30 executes a starting point fire control routine shown in FIG. 4 to be described later, so that the compression top dead center (TDC) is set based on the engine rotational fluctuation until the crank angle reference position is detected from the start of the starting control. Detection is performed, and ignition is performed after detection of the compression top dead center. When the engine speed is low at the start of the engine, the piston of the cylinder in the compression stroke rises and the engine speed decreases as the cylinder pressure increases. When the compression top dead center is exceeded, the cylinder pressure decreases and the engine speed decreases. Therefore, the engine rotational speed reverses from a decrease to an increase at the compression top dead center (see FIG. 5). Therefore, if the engine rotation speed is monitored and a position where the engine speed is reversed from a decrease to an increase is detected as the compression top dead center, the compression top dead center can be relatively accurately detected without detecting the crank angle reference position. It can be detected well. As a result, ignition can be executed at an appropriate timing after detection of compression top dead center, and the engine can be reliably started.
[0031]
Hereinafter, the processing content of each routine of FIG.3 and FIG.4 which this ECU30 performs is demonstrated.
The routine for determining whether or not the crank angle reference position is detected in FIG. 3 is started in synchronization with the crank angle pulse signal during execution of the start control based on the combustion pressure. When this routine is started, first, at step 101, it is determined whether or not the rotation angle of the crankshaft from the start of the engine has reached a predetermined crank angle (for example, 180 ° C.) that reduces the engine rotation fluctuation to some extent. Is determined on the basis of the number of counts of the crank angle pulse signal. When the rotation angle of the crankshaft from the start of starting does not reach a predetermined crank angle (for example, 180 ° C.), the engine rotation fluctuation is still large, and the pulse interval of the crank angle pulse signal is equal or uneven. Is judged difficult to proceed to step 103, and the detection of the crank angle reference position based on the crank angle pulse signals at unequal intervals is prohibited. During this crank angle reference position detection prohibition period, cylinder discrimination is made based on the engine stop position stored in the memory of the ECU 30, and fuel is injected into the cylinder in the expansion stroke or compression stroke (see FIG. 6). ).
[0032]
Thereafter, when the rotation angle of the crankshaft from the start of starting becomes equal to or greater than a predetermined crank angle (for example, 180 ° C.), it is determined “Yes” in step 101 and the process proceeds to step 102 where The detection of the crank angle reference position by the angular pulse signal is permitted. After that, it is determined whether the crank angle pulse signal has an equal interval or an unequal interval, and the position (missing portion) where the unequal interval crank angle pulse signal is generated is detected as the crank angle reference position. Crank angle pulse signals are equally spaced from the crank angle reference position, and the crank angle is detected based on the counted number.
[0033]
4 is started in synchronism with the crank angle pulse signal during execution of the start control by the combustion pressure. When this routine is started, first, at step 201, whether the rotation angle of the crankshaft from the start is within a predetermined crank angle (eg, 360 ° C.) that may not have detected the crank angle reference position. Is determined based on the number of counts of the crank angle pulse signal from the start of starting. As a result, if it is determined that the rotation angle of the crankshaft from the start of start exceeds a predetermined crank angle (eg, 360 ° C. A), this routine is terminated without performing the subsequent processing.
[0034]
On the other hand, if the rotation angle of the crankshaft from the start of start is within a predetermined crank angle (for example, 360 ° C.), the process proceeds to step 202 to determine whether or not the engine rotation speed has decreased, the pulse interval of the crank angle pulse signal. Judged based on the ratio. Specifically, it is determined whether or not the engine speed is decreasing depending on whether or not the ratio between the current pulse interval T (i) and the previous pulse interval T (i-1) is larger than the determination value. Here, the determination value is set to a value larger than 1.
[0035]
If it is determined in step 202 that the pulse interval ratio T (i) / T (i-1) of the crank angle pulse signal is larger than the determination value, it is determined that the engine speed is decreasing, and step Proceeding to 203, T (i) / T (i-1)> the rotation reduction counter C that counts the number of times of continuous determination is incremented by 1, and the routine proceeds to step 204 where the rotation reduction counter C is counted. Is equal to or greater than 2 (T (i) / T (i-1)> determined value and whether or not it is determined continuously twice or more). This determination in step 204 is to prevent erroneous determination of engine rotation reduction due to crank angle pulse signals at unequal intervals (missing teeth).
[0036]
If the rotation reduction counter C is 1, it is determined as “No” in step 204, and this routine is finished as it is. Thereafter, if the rotation decrease counter C becomes 2 or more, it is determined that the engine rotation speed is actually decreasing, and the process proceeds to step 205, where the rotation decrease detection flag X is “1” indicating that the rotation decrease has been detected. Set to "". The behavior of the rotation reduction counter C and the rotation reduction detection flag X as described above is illustrated in the time chart of FIG.
[0037]
Thereafter, when the direction of change of the engine rotation speed is reversed from the decrease direction to the increase direction, it is determined as “No” in Step 202 and the process proceeds to Step 206, where the rotation decrease detection flag X means “1” indicating that the rotation decrease has been detected. And when the rotation reduction detection flag X is “0” (when no rotation reduction is detected), the process proceeds to step 209 and the rotation reduction counter C is reset to zero.
[0038]
For example, if the engine speed is increased and the crank angle pulse signal is determined to be “Yes” in step 202 due to the crank angle pulse signal being unequally spaced and the rotation reduction counter C becomes 1, then the next time the routine is started, step 202 is executed. It is determined as “No”, and the process proceeds to Step 206. Since it is also determined as “No” in Step 206, the process proceeds to Step 209, and the rotation reduction counter C is reset (see FIG. 5). Thereby, erroneous detection of the compression top dead center by the crank angle pulse signal of unequal intervals (missing teeth) is prevented in advance.
[0039]
On the other hand, if the engine speed continues to decrease until the previous start of this routine, the rotation decrease counter C becomes 2 or more, and the rotation decrease detection flag X is set to “1”, then the engine rotation speed is When the routine reverses from decrease to increase, when this routine is started, it is determined as “No” in Step 202 and proceeds to Step 206. In Step 206, it is determined as “Yes”, whereby the compression top dead center is determined. Detected. Thereafter, the process proceeds to step 207, ignition is performed, and the process proceeds to step 208, where both the rotation decrease counter C and the rotation decrease detection flag X are reset. By such processing, a position where the engine speed is reversed from a decrease to an increase is detected as a compression top dead center, and ignition is performed after the detection of the compression top dead center. The timing for starting energization to the ignition circuit (not shown) is determined based on the engine stop position stored in the memory.
[0040]
In this routine, until the crankshaft rotation angle from the start of start reaches, for example, 360 ° C., the reduction / increase in engine speed is detected and the compression top dead center is detected. When the crankshaft rotation angle from the start of start exceeds 180 ° C. by the angle reference position detectability determination routine, the detection of the crank angle reference position is permitted, so that the crank angle reference position is detected from the start of start. Only during this period, the compression top dead center may be detected by determining the decrease / increase in engine speed. This is because after detecting the crank angle reference position, the compression top dead center can be detected based on the number of counts of the crank angle pulse signal.
[0041]
According to the embodiment (1) described above, the crankshafts with unequal intervals are kept until the rotation angle of the crankshaft from the start of the engine reaches a predetermined crank angle (for example, 180 ° C.) that reduces the engine rotation fluctuation to some extent. Since the detection of the crank angle reference position by the angular pulse signal is prohibited, it is possible to prevent erroneous detection of the crank angle reference position at the time when the engine rotation fluctuation at the initial start-up is large. During the crank angle reference position detection prohibition period, the cylinder is determined based on the stop position detected before the start (when the engine was stopped last time). Cylinder discrimination can be performed without detecting the reference position, erroneous injection and erroneous ignition can be prevented, and startability by combustion pressure can be improved.
[0042]
Further, in the present embodiment (1), when the engine rotation speed at the initial stage of start-up is low, considering the characteristic that the engine rotation speed reverses from a decrease to an increase at the compression top dead center, the pulse interval of the crank angle pulse signal is changed. Based on the ratio, the position where the engine rotation speed reverses from the decrease to the increase is detected as the compression top dead center, and the ignition is executed after the detection of the compression top dead center. In addition, the compression top dead center can be detected with relatively high accuracy. As a result, ignition can be executed at an appropriate timing after detection of compression top dead center, and the engine can be reliably started.
[0043]
<< Embodiment (2) >>
In the above embodiment (1), the detection prohibition period of the crank angle reference position is set based on the rotation angle of the crankshaft from the start of the start, but in the embodiment (2) of the present invention, FIG. By executing the crank angle reference position detection possibility determination routine, the crank angle reference position detection prohibition period is set to a period until the engine rotation fluctuation becomes a predetermined value or less.
[0044]
The routine for determining whether or not the crank angle reference position can be detected in FIG. 7 is started in synchronization with the crank angle pulse signal during execution of the start control based on the combustion pressure. When this routine is started, first, at step 301, it is determined whether or not the current crank angle estimated based on the stop position detected before the start (when the previous engine stopped) is near the crank angle reference position. If it is near the crank angle reference position, the process proceeds to step 303, and the detection of the crank angle reference position by the crank angle pulse signals at unequal intervals is permitted.
[0045]
On the other hand, if it is determined in step 301 that it is not near the crank angle reference position, the routine proceeds to step 302, where it is determined whether or not the engine rotation fluctuation is smaller than a predetermined value based on the pulse interval ratio of the crank angle pulse signal. . Specifically, the engine rotational fluctuation varies depending on whether or not the ratio of the current pulse interval T (i) and the previous pulse interval T (i-1) is within a predetermined range (lower limit value K1 to upper limit value K2). It is determined whether it is smaller than a predetermined value. Here, the lower limit value K1 of the predetermined range is set to a value smaller than 1, and the upper limit value K2 is set to a value larger than 1.
[0046]
If it is determined in step 302 that the pulse interval ratio T (i) / T (i-1) of the crank angle pulse signal is within the predetermined range, it is determined that the engine rotation fluctuation is smaller than the predetermined value. Proceeding to step 303, the detection of the crank angle reference position based on the crank angle pulse signals at irregular intervals is permitted.
[0047]
On the other hand, if the pulse interval ratio T (i) / T (i-1) of the crank angle pulse signal is out of the predetermined range, it is determined that the engine rotation fluctuation is larger than the predetermined value, and step 304 is executed. The detection of the crank angle reference position by the unequal interval crank angle pulse signal is prohibited.
[0048]
In the present embodiment (2) described above, the detection prohibition period of the crank angle reference position is set based on engine rotation fluctuations. Therefore, the engine start condition, fuel properties, changes with time, manufacturing variations, etc. Even if the increase behavior of the engine speed changes, there is an advantage that the detection prohibition period of the crank angle reference position can be appropriately set accordingly.
[0049]
Further, in the present embodiment, when it is determined that the current crank angle estimated based on the stop position detected before the start (when the previous engine stopped) is near the crank angle reference position, The detection of the crank angle reference position by the angular pulse signal is permitted. This is because when the engine speed decreases, it is possible to discriminate between equal / unequal intervals of the crank angle pulse signal, and the crank angle reference position can be detected normally. In this case, when the engine speed increases, the crank angle pulse signal (crank angle reference position) with unequal intervals cannot be detected. However, the crank angle pulse signal with unequal intervals is erroneously determined as the crank angle pulse signal with unequal intervals. Therefore, the problem of misignition and misinjection does not occur. Therefore, there is no problem even if the detection of the crank angle reference position is permitted in the vicinity of the crank angle reference position as in the present embodiment (2).
[0050]
Note that if it is determined that the current crank angle estimated based on the stop position detected before the start (when the engine was stopped last time) is close to the crank angle reference position, the crank angle pulse signal with unequal intervals is used. The detection of the corner reference position may be prohibited. Even in this case, since the cylinder can be determined based on the stop position detected before the start (when the engine is stopped last time), erroneous injection and erroneous ignition can be prevented, and the startability by the combustion pressure can be improved.
[0051]
<< Embodiment (3) >>
In the embodiment (3) of the present invention, by executing the crank angle reference position detection possibility determination routine of FIG. 8, the crank angle reference position detection prohibition period is set to a period until the engine speed reaches a predetermined value. I am doing so.
[0052]
The routine for determining whether or not the crank angle reference position can be detected in FIG. 8 is started in synchronization with the crank angle pulse signal during execution of the start control based on the combustion pressure. When this routine is started, first, at step 401, it is determined whether or not the engine speed detected based on the pulse interval of the crank angle pulse signal has reached a predetermined value (for example, 200 rpm). If it has not reached 200 rpm), it is determined that the engine rotational fluctuation is still large and it is difficult to accurately determine the equal interval / unequal interval of the crank angle pulse signal. The detection of the crank angle reference position by the equally spaced crank angle pulse signal is prohibited.
[0053]
Thereafter, when the engine speed reaches a predetermined value (for example, 200 rpm), “Yes” is determined in the above step 401, and the process proceeds to step 402, where the detection of the crank angle reference position by the unequal interval crank angle pulse signal is permitted. To do.
[0054]
In the embodiment (3) described above, the crank angle reference position detection prohibition period is set based on the engine speed, so that the engine start conditions, fuel properties, changes with time, manufacturing variations, etc. Even if the increase behavior of the engine speed changes, there is an advantage that the detection prohibition period of the crank angle reference position can be appropriately set accordingly.
[0055]
In each of the embodiments (1) to (3) described above, as a technique for prohibiting the detection of the crank angle reference position, a process for determining whether the pulse intervals of the crank angle pulse signal are equal intervals or not is not performed. However, during the crank angle reference position detection prohibition period, the determination value for determining whether the pulse interval of the crank angle pulse signal is equal or unequal is changed to a determination value that makes the unequal interval indistinguishable. By changing, detection of the crank angle reference position may be prohibited. In this way, the crank angle reference position can be detected without stopping the process of determining whether the pulse angle of the crank angle pulse signal is equal or unequal during the crank angle reference position detection prohibition period. Can be banned.
[0056]
Needless to say, the present invention is not limited to a four-cylinder engine and can be applied to an engine having three or less cylinders or five or more cylinders.
[Brief description of the drawings]
FIG. 1 is a diagram showing an entire engine control system according to an embodiment (1) of the present invention.
FIG. 2 is a diagram comparing the engine speed increase behavior between combustion-only start and starter start
FIG. 3 is a flowchart showing a process flow of a crank angle reference position detection possibility determination routine according to the embodiment (1).
FIG. 4 is a flowchart showing a process flow of a start-time fire control routine in the embodiment (1).
FIG. 5 is a time chart showing an example of start point fire control according to the embodiment (1).
FIG. 6 is a diagram showing the relationship between the stroke of each cylinder, the injection timing at the start, and the ignition timing
FIG. 7 is a flowchart showing a process flow of a crank angle reference position detection possibility determination routine according to the embodiment (2).
FIG. 8 is a flowchart showing a process flow of a crank angle reference position detection possibility determination routine according to the embodiment (3).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 24 ... Crank angle sensor (crank angle pulse signal generation means), 30 ... ECU (Crank angle detection) Means, start control means), 37... Signal rotor, 37 a.

Claims (5)

A crank angle pulse signal for generating a crank angle pulse signal at equal intervals according to the rotation of the internal combustion engine in a crank angle region excluding a predetermined crank angle reference position and generating crank angle pulse signals at unequal intervals at the crank angle reference position Generating means;
It is determined whether the crank angle pulse signal output from the crank angle pulse signal generating means has an equal interval or an unequal interval, and a position where the unequal interval crank angle pulse signal is generated is defined as the crank angle reference position. Crank angle detection means for detecting, counting the crank angle pulse signal at equal intervals from the crank angle reference position, and detecting the crank angle based on the count number;
An internal combustion engine start control device comprising start control means for performing start control for injecting and igniting fuel into a cylinder in an expansion stroke or a compression stroke at the start of the internal combustion engine;
Comprising stop position detecting means for detecting the stop position of the internal combustion engine;
The start control means prohibits detection of the crank angle reference position by the crank angle pulse signal at unequal intervals until a predetermined period elapses from the start of the start control, and determines the stop position detected by the stop position detection means. Means for executing cylinder injection control and / or ignition control with reference to a reference, and detecting a compression top dead center based on engine rotation fluctuation from the start of the start control until the crank angle reference position is detected. And a starting control device for an internal combustion engine, characterized by comprising means for executing ignition after detection of the compression top dead center .   The start control means makes a determination value for determining whether the pulse interval of the crank angle pulse signal is an equal interval or an unequal interval from the start of the start control to an unequal interval. 2. The start control device for an internal combustion engine according to claim 1, wherein detection of the crank angle reference position is prohibited by changing to a determination value.   The start control means sets the predetermined period during which detection of the crank angle reference position is prohibited to a period until the crankshaft rotation angle reaches a predetermined angle from the start of the start control. Item 3. The start control device for an internal combustion engine according to Item 1 or 2.   The internal combustion engine according to claim 1 or 2, wherein the start control means sets the predetermined period for prohibiting detection of the crank angle reference position as a period until the engine speed reaches a predetermined value. Start control device.   3. The internal combustion engine according to claim 1, wherein the start control unit sets the predetermined period for prohibiting the detection of the crank angle reference position to a period until the engine rotation fluctuation becomes a predetermined value or less. Engine start control device.

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