JP3539327B2 - Engine control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine control device.
[0002]
[Prior art]
The engine control device is a device that controls fuel injection control, ignition timing control, idle speed control, and the like, and operates the engine in an optimal state. That is, signals from various sensors such as a crank sensor and an engine water temperature sensor that detect an engine operating state are input to an electronic control unit (ECU) to control the optimal fuel injection amount, injection timing, ignition timing, and the like.
[0003]
Control synchronized with engine rotation such as ignition control and injection control, that is, control synchronized with the crank angle, is achieved by generating a signal such as an ignition pulse when an offset time from a crank edge (edge of a crank signal) has elapsed. I went.
[0004]
[Problems to be solved by the invention]
However, it is necessary to perform an operation for conversion from angle to time, and there is a demand to reduce processing load and improve accuracy.
[0005]
The present invention has been made under such a background, and an object of the present invention is to reduce the processing load and improve the accuracy and to perform an appropriate engine control even at a reference position of a crank signal. It is to provide a control device.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, a pulse interval measuring unit detects a crank signal having a reference position portion having an irregular pulse interval in the middle of a pulse train at a predetermined angular interval corresponding to the rotation of the crankshaft of the engine. The pulse interval is measured, and the multiplied signal generating means generates a multiplied signal of an integral multiple frequency by the next pulse based on the current pulse interval by the pulse interval measuring means. As described above, by generating a multiplied signal at a predetermined angle interval and synchronizing with the engine rotation, a calculation for converting from angle to time can be omitted, thereby reducing processing load and improving accuracy. Can be planned.
[0007]
Immediately after the reference position of the crank signal, the pulse interval measured by the pulse interval measuring means at the reference position is corrected by the pulse interval correction means. Therefore, even at the reference position of the crank signal, erroneous output of the multiplied signal based on the pulse interval can be prevented and proper engine control can be performed.
Further, the reference position portion of the crank signal is a missing tooth portion in which the pulse is extracted in the middle of the pulse train, and the correction of the measured pulse interval in the pulse interval correction means shortens the measured pulse interval. is there. Accordingly, when it is determined that a missing tooth has occurred at an unexpected location due to a missing tooth determination error or the like, the missing tooth is generated in a state where the pulse interval measurement is permitted. The pulse interval is measured, but correction can be made by shortening the pulse interval.
[0008]
According to the second aspect of the present invention, a pulse interval measuring means is used for a crank signal having a reference position portion having an unequal pulse interval in the middle of a pulse train at a predetermined angular interval corresponding to the rotation of the crankshaft of the engine. The pulse interval is measured, and the multiplied signal generating means generates a multiplied signal of an integral multiple frequency by the next pulse based on the current pulse interval by the pulse interval measuring means. As described above, by generating a multiplied signal at a predetermined angle interval and synchronizing with the engine rotation, a calculation for converting from angle to time can be omitted, thereby reducing processing load and improving accuracy. Can be planned.
[0009]
Further, the prohibiting means prohibits the pulse interval measuring means from measuring the pulse interval at the reference position before the reference position of the crank signal. Therefore, even at the reference position of the crank signal, erroneous output of the multiplied signal based on the pulse interval can be prevented and proper engine control can be performed.
[0010]
Further, after the prohibition means prohibits the measurement of the pulse interval by the prohibition means, the prohibition of the measurement of the pulse interval is released immediately after the reference position of the crank signal. If the pulse interval correction means detects an unequal pulse interval in the middle of the pulse train of the crank signal at an unexpected location, the pulse interval measured by the pulse interval measurement means is corrected. Therefore, when it is determined that the unequal pulse interval has occurred at an unexpected place due to a determination error of the reference position, etc., the unequal pulse interval occurs in a state where the pulse interval measurement is permitted. An unusual value (pulse interval) at the time of inequality is measured, but the pulse interval can be corrected.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[0012]
In this embodiment, the present invention is embodied in a control device for a multi-cylinder gasoline engine for an automobile. FIG. 1 shows a configuration of an engine control ECU 1 in the present embodiment. The engine control ECU 1 includes a microcomputer (hereinafter, referred to as a microcomputer) 10, a power supply circuit 20, an input / output circuit 30, and an EEPROM 40. The power supply circuit 20 receives a supply of power from the battery 2 and supplies a predetermined voltage to each device in the ECU 1. The microcomputer 10 includes a CPU 11, a ROM 12, a RAM 13, an A / D converter 14, an input / output interface 15, and a timer module 16, and these members exchange data with each other via a data bus. An EEPROM 40 is connected to the input / output interface 15, and data is exchanged with the EEPROM 40 via the input / output interface 15. The input / output circuit 30 receives signals from sensors and switches and outputs drive signals to injectors (fuel injection valves) and ignition devices. Further, the communication line 3 is connected to the input / output circuit 30, and data is exchanged with another ECU via the input / output circuit 30. The CPU 11 of the microcomputer 10 receives signals (data) from sensors and switches and data from the communication line 3 via the input / output circuit 30 and the input / output interface 15 and performs various calculations based on these data. The injector and the like are driven and controlled via the input / output interface 15 and the input / output circuit 30.
[0013]
Here, the signal taken by the engine control ECU 1 includes a crank signal from a crank sensor. FIG. 2 shows a crank signal for one engine cycle (720 ° CA). This crank signal is composed of a pulse train at predetermined angular intervals corresponding to the rotation of the crankshaft of the engine, and has a missing tooth portion (reference position portion) from which a pulse is extracted in the middle of this pulse train. That is, there is a reference position portion having unequal pulse intervals in the middle of the pulse train at every predetermined angular interval. In the present embodiment, the crank signal has a missing tooth configuration in which two pulses are missing every 60 pulses, and two missing tooth portions appear at 720 ° CA (the missing tooth portions are provided every 360 ° CA). This crank signal is input to the hard crank 100 of the timer module 16 in FIG. 1, and the CPU 11 creates a crank counter based on this signal. More specifically, as shown in FIG. 2, the crank counter counts up when a pulse of a crank signal is input, and is cleared to 0 at a timing when it reaches 120 for one engine cycle. The count of missing teeth is corrected when a crank pulse is input after the missing teeth.
[0014]
On the other hand, the hard crank 100 provided in the timer module 16 of FIG. 1 is a functional unit that processes a crank signal in a hardware manner. With the hard crank 100, the processing of the crank signal in FIG. 2 (determination of missing teeth and generation of an angle signal obtained by dividing the time between crank edges) can be performed in a hardware manner.
[0015]
FIG. 3 shows the configuration of the hard crank 100.
3, a frequency dividing circuit 101, an edge time measurement counter 102, an edge time storage register 103, a multiplication counter 104, a guard counter 105, a missing tooth determination counter 106, a reference counter 107, and an angle counter 108 are provided. The signal Pφ from the prescaler is sent to the edge time measurement counter 102 and the multiplication counter 104 via the frequency dividing circuit 101. The signal Pφ is sent to the angle counter 108. Further, the crank signal is sent to the edge time measurement counter 102, the guard counter 105, and the missing tooth determination counter 106.
[0016]
FIG. 4 shows a time chart of the angle signal generation (when there is no missing tooth). FIG. 4 shows an input crank signal, a count value of the edge time measurement counter 102, a stored value of the edge time storage register 103, a count value of the multiplication counter 104, an output signal of the multiplication counter 104 (multiplication clock), and a guard counter 105. , The count value of the reference counter 107, the count value of the angle counter 108, and the count value of the missing tooth determination counter 106.
[0017]
The edge time measurement counter 102 in FIG. 3 receives a crank signal and measures a time (pulse interval) between crank edges. More specifically, the edge time measurement counter 102 as a pulse interval measurement means is a counter that counts up in a time-synchronized manner as shown in FIG. 4, and measures the time between crank edges (between falling edges of a crank signal). The measured value is multiplied by 1 / n and transferred (reloaded) to the edge time storage register 103, and this data is also reloaded into the multiplication counter 104 at the same time. As the multiplication value (n value), for example, “32” can be cited.
[0018]
The multiplication counter 104 shown in FIG. 3 generates a multiplied clock obtained by dividing the crank edge time by 1 / n using the time between crank edges measured by the edge time measurement counter 102. More specifically, the multiplication counter 104 counts down in time synchronization as shown in FIG. 4, and when it reaches "0", generates a multiplication clock and reloads the value of the edge time storage register 103. As described above, the multiplying counter 104 as a multiplying signal generating means generates a multiplied signal (multiplied clock) having a frequency of an integral multiple before the next pulse based on the current pulse interval by the edge time measuring counter 102.
[0019]
The reference counter 107 in FIG. 3 performs a count-up operation by a multiplied clock as shown in FIG. The angle counter 108 in FIG. 3 counts up with a time synchronous clock (counts with an internal clock). The guard counter 105 is a counter that inputs a crank signal and counts up on the falling edge of the crank signal. At the same time as the input of the crank edge, a value n times (multiplied) the value before the count is input to the reference counter 107. Forward.
[0020]
Here, as shown in FIG. 4, the count value of the reference counter 107 cannot exceed the value (n times the count value) transferred from the guard counter 105 when the crank edge is input. The angle counter 108 counts up only when the value is smaller than the count value of the reference counter 107. An angle signal is generated in synchronization with the count up of the angle counter 108. Thus, the angle signals are generated by the three counters 105, 107, and 108.
[0021]
In the present embodiment, the internal clock (signal Pφ from the prescaler) is set to 20 MHz, and the angle counter 108 can operate at a higher speed than other counters. In FIG. 4, at the time of deceleration, as the counting operation of the reference counter 107 and the angle counter 108, the value of the reference counter 107 reaches n times the value of the guard counter 105 before the input of the crank edge. The count-up of 108 is prohibited. As a result, at the time of deceleration, the counting operation of the angle counter 108 is stopped, and the occurrence of an angle signal having a certain value or more is prevented. During acceleration, before the reference counter 107 catches up with the value n of the guard counter 105, the crank edge input transfers the value n times the value of the guard counter 105 to the reference counter 107, and the angle counter 108 It keeps counting up until it catches up with the reference counter 107. As a result, at the time of acceleration, the angle counter 108 counts up after the input of the crank edge, and generates an insufficient angle signal.
[0022]
The angle signal thus generated is input to a counter (not shown) in the hard crank 100, and ignition / injection control is performed in synchronization with the crank angle using a compare register. That is, by providing a system that generates a multiplied signal at a predetermined angular interval and synchronizes with the engine rotation, an operation for converting from angle to time can be omitted, and the processing load is reduced and the accuracy is improved (n = If it is 32, LSB = 0.1875 ° CA) can be achieved.
[0023]
The missing tooth determination counter 106 in FIG. 3 counts up by a multiplied clock and is cleared to 0 by a crank edge input. Therefore, as shown in FIG. 5, when the input of the crank edge due to the missing tooth does not exceed a predetermined time, the missing tooth determination value is reached, and the missing tooth interrupt signal is generated. More specifically, the missing tooth determination counter 106 compares the count value with the missing tooth determination value and generates a missing tooth interrupt signal at the crank edge after the count value becomes equal to the missing tooth determination value.
[0024]
The missing tooth interrupt signal may be generated when the count value of the missing tooth determination counter 106 reaches the missing tooth determination value. In this embodiment, the missing tooth determination value is set to 2.5 times the previous crank edge time.
[0025]
Next, the operation of the engine control ECU (engine control device) configured as described above will be described.
FIG. 5 is a time chart showing a correction method for missing teeth.
[0026]
If the input of the crank edge is not longer than a predetermined time during the missing tooth, the count value of the missing tooth determination counter 106 in FIG. 3 reaches the missing tooth determination value, and a missing tooth interrupt signal is generated.
[0027]
Here, in the present embodiment, two pulses are missed at the time of a missing tooth, so the edge time at the time of the missing tooth is three times as long as the normal time. That is, since the normal time value is reloaded to the edge time storage register 103 and the multiplication counter 104 in FIG. 3, the generation interval of the multiplication clock is also tripled, and the angle signal cannot be correctly generated without any change. In other words, in a system using a crank signal with a missing tooth, the interval between the edges of the missing tooth is longer than the interval between the edges other than the missing tooth. The interval between the angle signals is longer than the angle signal other than the missing tooth, so that ignition / injection control cannot be performed properly.
[0028]
The correction method for that will be described in detail with reference to the flowchart of FIG. The process of FIG. 6 is started at each falling edge of the crank signal.
In step 601 of FIG. 6, the CPU 11 determines from the value of the crank counter (see FIG. 2) whether or not it is a crank edge interrupt before missing teeth (crank counter = 56 or 116). Then, at the time of the crank edge interruption before the missing tooth, the CPU 11 determines in step 602 that the interval between the crank edges becomes three times the normal value at the time of the missing tooth, so that the count value of the guard counter 105 also becomes three times the normal value in advance. Is corrected as follows. That is, as the count value of the guard counter 105, the value of two shots missing by missing teeth due to edge input is added by software control. This is shown at the timing of t1 in FIG. 5, and the CPU 11 corrects the count value of the guard counter 105 by the missing tooth.
[0029]
If it is not the edge interruption before the missing tooth, the CPU 11 proceeds to step 603 in FIG. 6 and determines whether or not the edge interruption after the missing tooth (crank counter = 59 or 119). Then, at the time of the edge interruption after the missing tooth, the interval between the crank edges becomes three times as large as that of the missing tooth and the value is reloaded (timing of t2 in FIG. 5). The value obtained by multiplying the time by ３ is set in the edge time storage register 103 and the multiplication counter 104 in FIG. As a result, the generation interval of the multiplied clock can be generated after the missing tooth in the same manner as when the tooth is not a missing tooth. Therefore, the angle signal can be generated correctly, and the ignition / injection can be accurately controlled. .
[0030]
In this embodiment, the edge time is corrected by the edge interrupt after the missing tooth using the crank counter. However, the correction may be performed by the missing tooth interrupt signal from the missing tooth determination counter 106. In this case, the generation timing of the missing tooth interrupt signal is the time of the edge input after the missing tooth (the time of the falling edge input).
[0031]
As described above, this embodiment has the following features.
(A) The CPU 11 as the pulse interval correcting means executes steps 603 to 605 in FIG. 6 to measure the missing tooth portion (reference position portion) of the crank signal by the edge time measurement counter 102 immediately after the missing tooth portion. A value (corrected value) obtained by shortening the pulse interval by the number of extracted pulses is set in the edge time storage register 103 and the multiplication counter 104. Therefore, even in the missing tooth portion, erroneous output of the multiplied signal (multiplied clock) based on the pulse interval can be prevented, and appropriate engine control can be performed.
(Second embodiment)
Next, a second embodiment will be described focusing on differences from the first embodiment.
[0032]
FIG. 7 is a time chart illustrating a method of correcting missing teeth in the present embodiment.
In the method of this embodiment, reloading of the edge time storage register 103 and the multiplication counter 104 of the edge time at the next crank edge input is prohibited by the crank edge interrupt before the missing tooth. That is, by not using the edge time at the time of the missing tooth, it is possible to prevent the occurrence of the displacement (decrease) of the angle signal after the missing tooth. In FIG. 7, no transfer is performed at the timing of t10 because reloading is prohibited.
[0033]
FIG. 8 is a flowchart of the process at the crank edge before the missing tooth.
The CPU 11 determines in step 801 whether or not the interrupt is before the missing tooth (crank counter = 56 or 116) based on the value of the crank counter (see FIG. 2). Then, in the case of the crank edge interruption before the missing tooth, the CPU 11 determines in step 802 that the interval between the crank edges at the time of the crank edge before the missing tooth is three times the normal value, so that the count value of the guard counter 105 is also set to the normal value. The correction is made to be three times (process similar to step 602 in FIG. 6).
[0034]
After performing the processing in step 802, the CPU 11 prohibits in step 803 the reloading of the edge time storage register 103 and the multiplication counter 104 due to the crank edge input. In other words, since the interval between the crank edges of the missing tooth becomes three times as large as the normal time, the reload prohibition mode is set so that the edge time of the missing tooth is not used. This is shown at the timing of t11 in FIG. 7, and the mode is changed from the permission mode to the prohibition mode.
[0035]
If it is not the interruption before the missing tooth in step 801, the process ends without performing any processing.
FIG. 9 shows a flowchart of the process in the missing tooth interruption. As shown in FIG. 7, this process is started by a missing tooth interrupt signal at the time of inputting an edge after detecting a missing tooth by the missing tooth determination counter 106.
[0036]
The CPU 11 determines in step 901 whether reloading is prohibited. If so, reloading is permitted again in step 902 and the process ends. This is shown at the timing of t12 in FIG. 7, and the mode is changed from the inhibition mode to the permission mode.
[0037]
On the other hand, when it is determined that a missing tooth has occurred in an unexpected place due to a missing tooth determination error or the like (in the case of an abnormality), the missing tooth is generated in a state where reloading is permitted, so the value is three times larger than usual when the missing tooth is present. Are reloaded into the edge time storage register 103 and the multiplication counter 104. Therefore, if the reload is not prohibited in step 901, the CPU 11 proceeds to steps 903 and 904, and sets a value obtained by multiplying the edge time by １ ／ in the edge time storage register 103 and the multiplication counter 104. Thereby, the angle signal can be corrected in the same manner as in the first embodiment (the method in FIG. 5). In other words, it is possible to perform correction when a missing tooth occurs at an unexpected place such as when the hard crank 100 makes a mistake in missing tooth determination.
[0038]
As described above, this embodiment has the following features.
(A) The CPU 11 as the prohibiting means executes steps 801 and 803 in FIG. 8 to execute the pulse interval by the edge time measurement counter 102 at the missing tooth portion before the missing tooth portion (reference position portion) of the crank signal. Measurement was prohibited. Therefore, erroneous output of the multiplied signal based on the pulse interval can be prevented even at the missing tooth portion, and appropriate engine control can be performed. Further, after performing the steps 901 and 902 in FIG. 9 to prohibit the measurement of the pulse interval, the CPU 11 as the canceling unit and the pulse interval correcting unit immediately sets the pulse interval immediately after the missing tooth portion of the crank signal. In addition to canceling the prohibition of the measurement and executing steps 901, 903, and 904 in FIG. 9 and detecting a missing pulse (ie, unequal pulse interval) in the middle of the pulse train of the crank signal at an unexpected place, the edge time The pulse interval measured by the measurement counter 102 is corrected by shortening it by the number of missing pulses. Therefore, when it is determined that a missing tooth has occurred at an unexpected location due to a missing tooth determination error or the like, the missing tooth is generated in a state where the pulse interval measurement is permitted. Is measured, but correction can be made by reducing the pulse interval to a shorter value.
[0039]
In the above description, the reference position portion of the crank signal is a missing tooth portion in which a pulse is removed in the middle of a pulse train. However, the present invention is not limited to this, and other structures (such as inserting a pulse in the middle of a pulse train, etc.) In the pulse train at every predetermined angular interval, a reference position portion having unequal pulse intervals may be configured.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an engine control ECU according to an embodiment.
FIG. 2 is a time chart showing a crank signal for one cycle of an engine (720 ° CA) and a count value of a crank counter.
FIG. 3 is a configuration diagram of a hard crank.
FIG. 4 is a time chart for explaining generation of an angle signal by a hard crank.
FIG. 5 is a time chart for explaining correction of an angle signal at the time of missing teeth in the first embodiment.
FIG. 6 is a flowchart for explaining correction of an angle signal at the time of missing teeth.
FIG. 7 is a time chart for explaining correction of an angle signal at the time of a missing tooth in the second embodiment.
FIG. 8 is a flowchart for explaining correction of an angle signal at the time of missing teeth.
FIG. 9 is a flowchart for explaining correction of an angle signal at the time of missing teeth.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine control ECU, 10 ... Microcomputer, 11 ... CPU, 16 ... Timer module, 100 ... Hard crank, 102 ... Edge time measurement counter, 104 ... Multiplier counter, 106 ... Missing tooth determination counter.

Claims (3)

Pulse interval measuring means for measuring a pulse interval by inputting a crank signal having a reference position portion with an unequal pulse interval in the middle of a pulse train for each predetermined angular interval corresponding to rotation of the crankshaft of the engine,
A multiplied signal generating means for generating a multiplied signal of an integral multiple frequency until the next pulse based on the current pulse interval by the pulse interval measuring means,
Immediately after the reference position of the crank signal, pulse interval correction means for correcting the pulse interval measured by the pulse interval measurement means at the reference position,
The reference position portion of the crank signal is a missing tooth portion where the pulse is extracted in the middle of a pulse train, and the correction of the measured pulse interval in the pulse interval correction means shortens the measured pulse interval. An engine control device characterized by the above-mentioned. Pulse interval measuring means for measuring a pulse interval by inputting a crank signal having a reference position portion with an unequal pulse interval in the middle of a pulse train for each predetermined angular interval corresponding to rotation of the crankshaft of the engine,
A multiplied signal generating means for generating a multiplied signal of an integral multiple frequency until the next pulse based on the current pulse interval by the pulse interval measuring means,
In front of the reference position portion of the crank signal, prohibition means for prohibiting measurement of pulse intervals by the pulse interval measurement means at the reference position portion,
After prohibiting the measurement of the pulse interval by the prohibiting means, immediately after the reference position portion of the crank signal, release means for releasing the prohibition of the pulse interval measurement,
In an unexpected place, when detecting an unequal pulse interval in the middle of the pulse train of the crank signal, a pulse interval correction unit that corrects the pulse interval measured by the pulse interval measurement unit,
An engine control device comprising: The reference position portion of the crank signal is a missing tooth portion where the pulse is extracted in the middle of a pulse train, and the correction of the measured pulse interval in the pulse interval correction means is to shorten the measured pulse interval. Item 3. The engine control device according to item 2 .

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