JP3975982B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device used for a multi-cylinder engine.

  In an engine control apparatus that performs this type of fuel injection, particularly independent injection, cylinder discrimination of the engine is indispensable. At the start of engine rotation, fuel injection (independent injection) is performed until cylinder discrimination by detection of the reference position is completed. Can not do. Therefore, conventionally proposed engine control devices include a device that starts independent injection after cylinder discrimination without performing fuel injection until the first cylinder discrimination after the start of engine rotation is performed, and synchronizes with the start of engine rotation. Thus, it can be roughly classified into a device that performs preliminary injection for all cylinders and shifts to independent injection after cylinder discrimination. The latter control device has been proposed as an improvement of the former control device, and for example, Japanese Patent Application Laid-Open Nos. 1-170735 and 3-54337 are publicly known.

  Hereinafter, the control operation of the conventional engine control device will be described with reference to the timing chart of FIG. 14 showing the operation immediately after the start of engine rotation. FIG. 14 shows an example of a 4-cycle 6-cylinder engine. The first cylinder (# 1) to the sixth cylinder (# 6) are # 1 → # 2 → # 3 → # 4 → # 5 → # 6 → #. It is ignited in order of 1. The crank angle signal NE is output every 30 ° CA, and the reference position signals G1 and G2 are output immediately before the TDC of the fourth cylinder and the first cylinder, respectively.

  When engine rotation is started at time t11, the first reference is made at time t13 after elapse of a mask period (time t11 to t12) for preventing erroneous detection of the crank angle signal NE and the reference position signals G1 and G2. A position signal G1 is detected. At this time, the fourth cylinder is determined based on the reference position signal G1. At time t14, a fuel injection signal is sent to the second cylinder having the intake stroke after time t13 when the cylinder is first discriminated, and thereafter in the cylinder order of # 2 → # 3 → # 4. Independent injection is performed.

  Further, when preliminary injection is performed on all cylinders in synchronism with the start of engine rotation, fuel injection is simultaneously performed at all the cylinders at time t11 as indicated by a broken line in FIG. 14, and thereafter, independent injection is performed at time t14. It is transferred to.

On the other hand, the first ignition signal after the start of engine rotation is set after the first cylinder discrimination at time t13. That is, when the ignition timing is TDC of each cylinder, the first spark is generated at the falling edge of the ignition signal at time t15 (at this time, the first ignition cylinder in FIG. 14 is the fifth cylinder). Thereafter, ignition is performed in the order of cylinders # 5 → # 6 → # 1.
JP-A-01-170735 Japanese Patent Laid-Open No. 03-054337

  However, the conventional engine control device has the following problems. First, if no fuel injection is performed before cylinder discrimination (before time t13 in FIG. 14), independent injection is started at time t14 (TDC of the fourth cylinder), and the first injection cylinder at this time is the second cylinder. It becomes. The fuel sucked into the second cylinder is ignited at time t16, which is TDC of the second cylinder. That is, the first explosion (first explosion) occurs at time t16. That is, during the period from time t13 to t16, the fifth, sixth, and first cylinders are ignited, but these cylinders cannot obtain the first explosion because the fuel has not yet been sucked, resulting in wasted fire. . As a result, after the engine starts rotating, there is no initial explosion for two rotations (period t11 to t16), which causes a problem that the startability of the engine is deteriorated.

  Further, when preliminary injection is performed for all cylinders at the start of engine rotation, intake fuel by preliminary injection is ignited at time t15 and initial explosion occurs, and intake fuel by preliminary injection also occurs in the subsequent sixth and first cylinders. An explosion occurs. Therefore, the startability of the engine is remarkably improved as compared with the former case. However, in this case, the intake fuel of the second, third, and fourth cylinders among all the cylinders that are pre-injected is exhausted without being ignited, which causes a problem of unburned gas discharge.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide an engine control device capable of suppressing the discharge of unburned gas and improving the startability of the engine. It is in.

  In order to achieve the above object, an engine control apparatus according to the present invention is used for an engine having a plurality of cylinders, and is set to a crank angle detecting means for detecting a crank angle of the engine and a predetermined crank angle. Fuel injection control based on the reference position detected by the reference position detection means at the first reference position detected by the reference position detection means after the start of engine rotation and the reference position detection means for detecting the reference position Engine control means for starting ignition control, stop crank angle detection means for detecting a crank angle at the time of engine rotation stop based on a detection result by the crank angle detection means, and stop crank detected by the stop crank angle detection means At least the beginning of the intake stroke is included between the angle and the next reference position following the stop crank angle. Pre-injection cylinder discriminating means for setting the cylinder to be the pre-injection cylinder, and the engine control means supplies fuel to the pre-injection cylinder after the start of rotation of the engine until the first reference position is detected. The gist is that the ignition control is not performed until the first reference position is detected while the fuel is injected.

    Example 1

Hereinafter, a first embodiment in which the engine control device of the present invention is embodied in a spark ignition type four-cycle six-cylinder engine will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing the configuration of the engine control apparatus in the present embodiment. In FIG. 1, a crank angle sensor 1 includes a crank angle rotor 2 fixed to a crankshaft of an engine and a magnetic pickup coil 3. The outer periphery of the crank angle rotor 2 is provided with teeth 2a every 10 ° CA (crank angle), and a part thereof is provided with a missing tooth portion 2b in which two teeth 2a are missing. In this embodiment, the crank angle sensor 1 constitutes a crank angle detecting means.

  The cam angle sensor 4 is composed of a cam angle rotor 5 fixed to a cam shaft that rotates 1/2 by one rotation of the crankshaft of the engine, and a magnetic pickup coil 6. One protrusion 5 a is provided on the outer periphery of the cam angle rotor 5. In this embodiment, the cam angle sensor 4 constitutes a reference position detecting means.

  A waveform shaping circuit 7 is connected to the crank angle sensor 1 and the cam angle sensor 4, and the waveform shaping circuit 7 shapes the output signals of both sensors 1 and 4 at a predetermined threshold as shown in FIG. Thus, a binary pulse signal is generated. That is, the waveform shaping circuit 7 generates a crank angle signal NE every 10 ° CA (a part excluding the tooth missing portion 2b) according to the output signal of the crank angle sensor 1, and also according to the output signal of the cam angle sensor 4. A reference position signal G for every 720 ° CA is generated.

  The waveform shaping circuit 7 is connected to a microcomputer (hereinafter abbreviated as a microcomputer) 8. The microcomputer 8 inputs a crank angle signal NE and a reference position signal G from the waveform shaping circuit 7 to 360 ° CA. The reference position is detected every time. The microcomputer 8 is a well-known logical operation circuit including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), backup RAM, input / output (I / O) port, and the like. The microcomputer 8 detects the engine speed based on the crank angle signal NE. The microcomputer 8 receives a signal output from the sensor group 9. The sensor group 9 includes an intake pressure sensor 10, a water temperature sensor 11, and the like, and the microcomputer 8 detects intake pressure, water temperature, and the like based on detection signals from the sensors.

  On the other hand, injectors 12A to 12F are disposed in the intake pipes (not shown) of the first cylinder (# 1) to the sixth cylinder (# 6), and the microcomputer 8 is based on the detection results of the various sensors. The fuel injection amounts by 12A to 12F are calculated, and the injectors 12A to 12F are driven by the same calculation signal (fuel injection signal). Thus, the injectors 12A to 12F execute independent injection in a predetermined cylinder order (in order of # 1 → # 2 → # 3 → # 4 → # 5 → # 6 → # 1). The igniter 13 drives an ignition plug (not shown) of each cylinder, and the microcomputer 8 obtains an ignition signal IGT based on the detection results of the various sensors and outputs it to the igniter 13. Thus, the spark plug is driven in a predetermined cylinder order (similar order to the injector) based on the ignition signal IGT, and a spark is generated.

  Further, a battery 14 is connected to the microcomputer 8 via a key switch 15. The key switch 15 has switching positions of “OFF”, “ON”, and “START”. When the key switch 15 is switched from the “OFF” position to the “ON” position by a key (not shown), power is supplied from the battery 14 to the microcomputer 8 and the microcomputer 8 is activated, and the CPU in the microcomputer 8 is stored in the ROM. Execute various control programs. When the key switch 15 is switched to the “START” position, in addition to supplying power to the microcomputer 8, power is supplied from the battery 14 to the starter motor 16, and initial rotation is applied to the stopped engine.

  In the present embodiment, the microcomputer 8 constitutes first engine control means, stop crank angle detection means, preliminary injection cylinder discrimination means, and second engine control means.

  Next, the operation of the engine control apparatus according to this embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing a control routine of the independent injection process and the ignition process of each cylinder, and the microcomputer 8 starts the routine of FIG. 3 every time the edge of the crank angle signal NE is detected. 4 and 5 are flowcharts showing the subroutine of FIG. FIGS. 6 and 7 are flowcharts showing a control routine related to the preliminary injection process at the start of engine rotation. The microcomputer 8 starts the routines shown in FIGS. 6 and 7 every predetermined time (for example, every 100 ms). To do. 8 is a reference table storing cylinder information for preliminary injection, FIG. 9 is a diagram for explaining the reference table of FIG. 8, and FIG. 10 is a timing chart for explaining the control operation of the microcomputer 8. .

  When the routine of FIG. 3 is started, the microcomputer 8 first executes a crank counter update process at step 100 (this corresponds to the subroutine of FIG. 4). The crank counter is counted up according to the crank angle accompanying the rotation of the engine, and is updated at a rate of once every three edges of the crank angle signal NE as shown in the subroutine of FIG. The first and fourth cylinders TDC are set to predetermined values.

  Specifically, in FIG. 4, the microcomputer 8 first increments the edge counter n by “1” in step 200 (the edge counter n is counted every time the edge of the crank angle signal NE is detected). It is determined whether it is 3 ”or more.

  If n ≧ 3, the microcomputer 8 proceeds to step 220 and clears the edge counter n to “0”, and then proceeds to step 230. In step 230, the microcomputer 8 updates the count value of the crank counter to a value incremented by “1”, and then proceeds to step 240. At this time, a 2-digit hexadecimal number is used as the count value of the crank counter, and in the following description, this count value is described as (XX) 16. Therefore, if the crank counter is initialized to (00) 16 when the microcomputer 8 is powered on, the count value is (00) 16, (01) 16, (02) 16.・ Counted like

  On the other hand, if n <3 in step 210, the microcomputer 8 proceeds to step 240 as it is. As described above, according to the processing of steps 200 to 230, the crank counter is incremented at a rate of once every three edges of the crank angle signal NE (a rate of once every 30 ° CA).

  Thereafter, in step 240, the microcomputer 8 determines whether or not the current crank angle has reached the missing tooth position (the position of the missing tooth portion 2b of the crank angle rotor 2). Specifically, the microcomputer 8 measures the required time Tn (see FIG. 2) between the edges of the crank angle signal NE, and calculates the required time Tn-1 between the previous edges and the required time Tn between the current edges. Compare. Then, for example, when Tn> 2.5 · Tn−1 is established, the microcomputer 8 determines that the tooth missing position is affirmative and makes an affirmative determination in step 240, and proceeds to step 250. If the determination in step 240 is negative, the microcomputer 8 ends this routine as it is.

  In step 250, the microcomputer 8 determines whether an edge of the reference position signal G is detected. If the edge of the reference position signal G is detected, the microcomputer 8 sets the crank counter to (00) 16 in step 260, and then ends this routine. If the edge of the reference position signal G is not detected, the microcomputer 8 sets the crank counter to (10) 16 in step 270, and then ends this routine.

  In short, the tooth missing position (the tooth missing portion 2b of the crank angle rotor 2) is detected every 360 ° CA (immediately before the TDC of the first and fourth cylinders), and the edge of the reference position signal G is every 720 ° CA (first). It is detected immediately before the TDC of one cylinder). Therefore, the TDC of the first cylinder can be detected when both of the steps 240 and 250 are positively determined, and the TDC of the fourth cylinder is detected when the positive determination of the step 240 and negative determination of the step 250 are made. can do. The TDC of the first cylinder and the TDC of the fourth cylinder are reference positions accompanying the rotation of the engine. In the TDC of the first cylinder and the TDC of the fourth cylinder, the crank counter is always set to (00) 16, (10) 16, and the deviation between the count value of the crank counter and the actual crank angle is prevented. Is done.

  Returning to the description of the routine of FIG. 3, after the processing of step 100, the microcomputer 8 proceeds to step 110 and determines whether or not the flag F is “0”. The flag F becomes “0” when the engine starts rotating, and is set to “1” when the first ignition process and the fuel injection process after the engine starts rotating. If F = 1, the microcomputer 8 proceeds to step 120 and executes an ignition process and a fuel injection process during normal operation according to the subroutine of FIG.

  In the routine of FIG. 5, the microcomputer 8 determines in step 300 whether or not the current crank angle is the TDC of any cylinder, and if it is not the TDC of any cylinder, it is not the timing for executing the ignition process and the fuel injection process. The routine is terminated as follows. If it is a TDC of any cylinder, the microcomputer 8 sets the ignition timing at step 310 and sets the fuel injection amount at step 320. Note that the ignition timing setting and the fuel injection amount setting here follow a well-known setting method and will not be described in detail, but in brief, for example, an ignition timing map (not shown) is used for setting the ignition timing. The ignition timing according to the engine speed and intake pressure at that time is required. In setting the fuel injection amount, for example, a fuel injection amount map (not shown) is used, and the fuel injection amount corresponding to the engine speed and the intake pressure at that time is obtained.

  On the other hand, if F = 0 in step 110 of FIG. 3, the microcomputer 8 proceeds to step 130, and whether or not the current crank angle is the missing tooth position, that is, the TDC of the first cylinder or the TDC of the fourth cylinder. It is determined whether or not any of the above. Then, the microcomputer 8 ends the routine as it is if the determination in step 130 is negative, and proceeds to step 140 if the determination in step 130 is affirmative and sets the ignition timing. The ignition timing set in step 140 is different from the ignition timing in step 120 described above, and the microcomputer 8 generates the ignition signal IGT so that a spark is generated at ATDC 10 ° CA of the first cylinder or the fourth cylinder. Set. That is, at the first ignition after the start of engine rotation, energization to the ignition coil is started at the TDC of the first cylinder or the fourth cylinder, and the energization is cut off at ATDC 10 ° CA.

  Thereafter, the microcomputer 8 determines in step 150 whether the current TDC is the TDC of the first cylinder or the TDC of the fourth cylinder. If the first cylinder TDC, the microcomputer 8 proceeds to step 160 and injects fuel into the fourth cylinder. If the fourth cylinder TDC, the microcomputer 8 proceeds to step 170 and injects fuel into the first cylinder. Thereafter, the microcomputer 8 sets the flag F to “1” in step 180 and ends the routine.

  Next, the preliminary injection process at the start of engine rotation will be described with reference to FIGS. Here, the pre-injection process stores a fuel injection cylinder (referred to as a specific cylinder for convenience) at the start of the next engine rotation when the engine stops, and stores the fuel injection cylinder in the specific cylinder at the start of engine rotation. Only the fuel injection is performed. Information regarding the specific cylinder is stored in advance in a reference table (FIG. 8) in the ROM, and the microcomputer 8 selects the specific cylinder using the reference table.

  More specifically, in the reference table of FIG. 8, the TDC of the first cylinder is set to 0 ° CA and the engine rotation (720 ° CA) is divided into six equal parts, and each region is divided into “A” to “F”. Yes. Then, the cylinder corresponding to the region is selected as a specific cylinder depending on which region the crank angle at the time of engine rotation stop is (the selected cylinder is indicated by a circle).

  The specific cylinder selected by FIG. 8 follows the positional relationship between each region and the intake stroke of each cylinder shown in FIG. 9, and from the crank angle at the start of engine rotation to the input of the first reference position signal. The cylinder having the intake stroke during this period is set as the specific cylinder. As a result, any one of the one to three cylinders becomes the specific cylinder. For example, when the crank angle is in the “A” region of FIG. 9, the cylinders that the intake stroke has until the next input of the reference position signal (TDC of the fourth cylinder) are the fifth cylinder and the sixth cylinder, This cylinder is the selected cylinder. The same applies to other regions. Therefore, by using the reference table of FIG. 8, the minimum number of injection cylinders required to accelerate the initial explosion and prevent the discharge of unburned gas is surely selected. The microcomputer 8 obtains the crank angle from the count value of the crank counter temporarily stored in the RAM, and selects a specific cylinder from the count value at that time.

  When the routine of FIG. 6 is started, the microcomputer 8 determines in step 400 whether or not the key switch 15 is in the “OFF” position. If the microcomputer 8 is not in the “OFF” position, the routine ends. If it is in the “OFF” position, the routine proceeds to step 410. In step 410, the microcomputer 8 reads out the RAM value of the crank counter according to the routine of FIG. 4, and selects a specific cylinder corresponding to the RAM value of the crank counter using the reference table of FIG. 8 described above, and backs up the specific cylinder. Store in RAM. Thereafter, the microcomputer 8 shuts off the power switch in the microcomputer 8 in step 420 and ends the routine. The specific cylinder information can be obtained by the process of FIG. 6, and the information is stored and retained even after the power is shut off after the engine is stopped.

  When the routine of FIG. 7 is started, the microcomputer 8 determines in step 500 whether or not the key switch 15 is in the “START” position. If the microcomputer 8 is not in the “START” position, the routine ends. If it is in the “START” position, the microcomputer 8 proceeds to step 510. In step 510, the microcomputer 8 reads the specific cylinder stored in the routine of FIG. 6 described above from the backup RAM, and outputs a fuel injection signal to inject fuel into the specific cylinder. By the processing of FIG. 7, the stored specific cylinder is surely ignited.

  Next, the control operation after the start of engine rotation will be described with reference to the timing chart of FIG. The time t0 in FIG. 10 indicates the engine rotation start time, the times t0 to t1 indicate the mask periods of the signals NE and G, and the time t2 indicates the time at which the first reference position after the engine rotation starts is detected.

  The crank angle “P1” (660 ° CA in the figure) at the start of engine rotation is reversed by 30 ° CA from the crank angle “P2” (690 ° CA in the figure) at the previous engine stoppage. The angle is The count value of the crank counter when the engine stops is (1A) 16 (this corresponds to the “F” region in FIG. 8), and the backup RAM includes fourth, fifth, fifth as specific cylinder information. The sixth cylinder is stored.

  In FIG. 10, the engine starts to rotate at time t0. That is, at time t0, the key switch 15 is switched from the “OFF” position to the “ON” and “START” positions, and the starter motor 16 is activated. Further, at time t0, step 500 in FIG. 7 is positively determined, and fuel is simultaneously injected into the fourth, fifth, and sixth cylinders stored as specific cylinders.

  Here, at time t0 to t1, the crank angle signal NE and the reference position signal G are masked for a certain period (for example, 100 to 150 msec), and cylinder discrimination is not performed. This is because, when the crank angle sensor 1 and the cam angle sensor 4 are configured by a magnetic pickup coil as in the present embodiment, the signal detection accuracy in a minute rotation range (for example, 20 rpm or less) is lowered. It is. Therefore, in this embodiment, a predetermined time immediately after the start of engine rotation is used as a mask period for the detection signal. Immediately after the start of engine rotation, the signals NE and G may be erroneously detected due to voltage fluctuations of the battery 14 and vibration due to the starter motor 16 being activated. Then, the routine of FIG. 3 is started at time t1 when the mask period has elapsed.

  Thereafter, the first cylinder discrimination is performed at time t2, and the TDC of the fourth cylinder is detected. Also, at this time t2, the crank counter is set to (10) 16, and the deviation between the crank counter and the actual crank angle caused by the reversal of the crank angle ("P2" → "P1") and the mask period is eliminated. The Then, the ignition signal IGT is generated according to the routine of FIG. 3, and the spark plug of the fourth cylinder generates a spark at time t3 (ATDC of the fourth cylinder 10 ° CA). At this time, since the fuel is sucked into the fourth cylinder by the preliminary injection, the first explosion occurs. Thereafter, after the second ignition, normal ignition control is performed, and a spark is generated at the TDC of each cylinder.

  Further, after time t2, the fuel injection is shifted to the independent injection by the routine of FIG. At this time, the starting cylinder of the independent injection is the first cylinder, and preliminary injection is not performed on the first cylinder, so that the first fuel suction is performed at time t2. Thereafter, independent injection is performed in the order of # 1 → # 2 → # 3.

  As described above in detail, in the engine control apparatus of the first embodiment, the count value of the crank counter corresponding to the crank angle is updated with the rotation of the engine (by the routine of FIG. 4). Then, the crank angle when the engine stops is detected by the count value of the crank counter, and a specific cylinder (injection cylinder at the time of preliminary injection) corresponding to the count value is selected and backed up using the reference table of FIG. Stored in RAM (by routine of FIG. 6). The specific cylinder selected according to FIG. 8 is a cylinder having an intake stroke between a crank angle when the engine stops rotating and a next reference position following the crank angle. At the start of engine rotation, the specific cylinder stored in the backup RAM is read out, and preliminary injection is performed on the specific cylinder (by the routine of FIG. 7). Further, after the detection of the first reference position after the start of engine rotation, the fuel injection is shifted to the independent injection for each cylinder and the ignition process is started for each cylinder (by the routine of FIG. 3).

  In short, according to the configuration of the present embodiment, during the period from the start of engine rotation to the detection of the first reference position, the preliminary injection is performed in accordance with the intake stroke, so that the injected fuel by the preliminary injection is in the intake stroke. It is reliably sucked into the cylinder and can be reliably burned by the subsequent ignition process. As a result, discharge of unburned gas can be suppressed. Further, when the ignition process is performed based on the first reference position, the fuel sucked by the preliminary injection can be burned, so that the initial explosion is accelerated and the startability of the engine can be improved.

  In the above example, only the case where the rotation stop position of the engine is set to the “F” region in FIG. 8 has been described, but the object of the present invention can be achieved even if the stop position is in another region. Needless to say.

  On the other hand, the method for selecting a specific cylinder may be changed in addition to the reference table shown in FIG. 8, and another specific example will be described next. In the reference table of FIG. 8 described above, the “A” to “F” regions are divided in synchronization with the TDC of each cylinder. However, in the reference table shown in FIG. 11, a part of the region of FIG. , New “A ′” to “F ′” regions are divided. That is, in the reference table of FIG. 11, the “A ′” and “D ′” regions are set to the crank angle region that is retarded by 30 ° CA from the “A” and “D” regions of FIG. Further, the “B ′” and “E ′” regions in FIG. 11 are set to the crank angle region on the retard side by 30 ° CA only from the “B” and “E” regions in FIG. The “F ′” region is set to the crank angle region on the retard side by 30 ° CA only at the end of the “C” and “F” regions in FIG.

And by selecting a specific cylinder using FIG. 11, the rotation stop angle of the engine was in the region from the start of the intake stroke to 30 ° CA for the first, second, fourth and fifth cylinders. In this case, the cylinder can be selected as the specific cylinder. For example, when the rotation stop position of the engine is 0 to 30 ° CA, only the fifth and sixth cylinders are specified cylinders in FIG. 8, whereas the fourth cylinder is added to the two cylinders in FIG. Is also a specific cylinder. That is, even if the rotation start position of the engine is already at the beginning of the intake stroke, fuel can actually be sucked, so that preliminary injection is also performed on this cylinder. As a result, the first explosion can be accelerated.

  In FIG. 11, the boundary angle between the “B ′” region and the “C ′” region and the boundary angle between the “E ′” region and the “F ′” region are on the retard side with respect to the case of FIG. Not shifted. In other words, when a large deviation occurs between the engine rotation stop position (memory angle) and the rotation start position (actual angle), the reference position (TDC of the first and fourth cylinders) immediately after the engine rotation starts. For this reason, only the area close to the reference position is not retarded. For example, when the end angle of the “B ′” region is 270 ° CA, this angle is BTDC 90 ° CA of the fourth cylinder. If the difference between the stored angle and the actual angle is large (90 ° CA or more), the TDC of the fourth cylinder cannot be detected and the sixth cylinder cannot be ignited. Therefore, when the end angle of the “B ′” region is set to 270 ° CA and preliminary injection is performed to the sixth cylinder in the region of 240 to 270 ° CA, the injected fuel for the sixth cylinder is released as unburned gas. May occur. When it is not necessary to consider the inconvenience due to the above reason, all the areas “A ′” to “F ′” are shifted to the retard side with respect to the “A” to “F” areas in FIG. Can also be materialized.

FIG. 12 shows another example in which the reference table is embodied. In this case, when the “A” to “F” region of the reference table and the intake stroke of each cylinder overlap, preliminary injection of the overlapped cylinder is not performed. Referring to FIG. 9, for example, in the “A” region, this region and the intake strokes of the third and fourth cylinders overlap. Accordingly, in this case, four cylinders other than the third and fourth cylinders are selected as specific cylinders, and preliminary injection is performed. In the reference table of FIG. 12, four cylinders are selected as specific cylinders in the regions other than the “A” region.
(Example 2)

  Next, a second embodiment of the present invention will be described with reference to FIG. In the first embodiment, when a plurality of specific cylinders are selected, preliminary injection is performed simultaneously for all the specific cylinders. However, in the second embodiment, simultaneous injection is performed when there are a plurality of specific cylinders. Independent injection is performed even if preliminary injection is not performed.

  Specifically, in the second embodiment, independent injection is performed by the crank counter of the backup RAM in step 510 of FIG. That is, the crank counter is set so that the start angle of the intake stroke corresponds to the specific cylinder, and the specific cylinder is independently injected in the corresponding exhaust stroke (60 ° CA before the start of the intake stroke). Then, at the start of engine rotation, fuel injection is performed independently only to the first cylinder to be ignited among the specific cylinders, and then fuel is injected into the next ignition cylinder when the crank counter reaches the set count value. Let

  FIG. 13 is a timing chart for explaining the second embodiment. In the second embodiment, unlike the first embodiment, the crank counter is not initialized when the microcomputer 8 is powered on. That is, the value of the crank counter when the engine stops is stored in the backup RAM, and after the engine starts rotating, the count-up is started following the stored value of the backup RAM. When the count value reaches (1B) 16, it is updated to (00) 16. As a result, the count value can correspond to the actual crank angle.

  In FIG. 13, at time t <b> 0 when engine rotation is started, preliminary injection is performed independently only on the fourth cylinder among the specific cylinders. Thereafter, the crank counter is started to be updated at time t1, and the count value becomes (00) 16 at time ta. That is, in FIG. 13, a shift of 60 ° CA occurs between the count value of the crank counter and the actual crank angle from time t1 to t2.

  At time tb, the fifth cylinder is considered to be 60 ° CA before the start of the intake stroke based on the count value of the crank counter (actually, the start angle of the intake stroke), and the fifth cylinder, which is the specific cylinder, is set. Preliminary injection is performed independently. Also at time tc, as with time tb, preliminary injection is performed independently for the sixth cylinder at the start angle of the intake stroke. In this way, independent injection is sequentially executed in accordance with the crank counter updated in FIG.

  In the case of FIG. 13, the actual crank angle of the engine and the value of the crank counter are shifted by 60 ° CA. Therefore, although it is originally desired to inject fuel in the exhaust stroke (60 ° CA before the start of the intake stroke). In fact, it is the start angle of the intake stroke at times tb and tc. However, in this case, there is no problem because sufficient fuel can be sucked in the corresponding intake stroke. When the specific cylinder is independently injected, the injection angle can be retarded from the above case to the first half of the intake stroke.

  In addition, this invention is not limited to the said Example, It can embody in the following aspect. In the above embodiment, the reference position is set every 360 ° CA (once per engine rotation), but this setting interval can be changed. For example, the reference position may be set every 120 ° CA and one reference position may be detected for each cylinder. In this case, since the start interval of the intake stroke between the cylinders is 120 ° CA, the cylinder having the intake stroke from the start of engine rotation to the detection of the first reference position is always one cylinder, and the backup RAM Always stores information for one cylinder. As a result, the area required for storage in the backup RAM is reduced, the number of preliminary injection cylinders is reduced, and the normal injection control can be quickly performed.

  In the above embodiments, specific examples using a six-cylinder engine have been shown. However, other multi-cylinder engines (four cylinders, eight cylinders, etc.) may of course be used. In this case, the reference table is changed and set according to the number of cylinders and the reference position.

  In the above embodiment, the cylinder number is selected from the reference table of FIG. 8 as the specific cylinder information and the cylinder number is stored and held in the backup RAM. However, the count value of the crank counter may be stored and held. . In this case, a specific cylinder for preliminary injection is selected at the start of engine rotation.

  Further, in the above embodiment, a mask period of a certain period is provided at the start of engine rotation. However, by using a magnetic crank angle sensor using a Hall element, signal detection in a minute rotation range (near 0 rpm) is possible. This makes it possible to omit the mask period.

It is a block diagram which shows roughly the engine control apparatus in the Example which actualized this invention. It is the wave form diagram which showed the output signal of a crank angle sensor and a cam angle sensor. It is the flowchart which showed the control routine of an independent injection process and an ignition process. FIG. 4 is a flowchart showing a crank counter update process in the subroutine of FIG. 3. FIG. FIG. 4 is a flowchart illustrating an ignition process and a fuel injection process during normal operation, which is a subroutine of FIG. 3. It is the flowchart which showed the routine which memorize | stores the specific cylinder for preliminary injection. It is the flowchart which showed the routine which concerns on a preliminary injection process. It is the reference table which memorize | stored the cylinder information for preliminary injection. FIG. 4 is a relationship diagram between a crank angle and a cycle of each cylinder. It is a timing chart for demonstrating operation | movement of the microcomputer in 1st Example. It is the reference table which memorize | stored the cylinder information for the preliminary injection in another example of 1st Example. Similarly, a reference table storing cylinder information for preliminary injection in another example of the first embodiment. It is a timing chart for demonstrating operation | movement of the microcomputer in 2nd Example. It is a timing chart for demonstrating the conventional engine control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crank angle sensor as crank angle detection means 4 Cam angle sensor as reference position detection means 8 Microcomputer as engine control means, stop crank angle detection means, preliminary injection cylinder discrimination means

Claims (1)

Used for an engine having a plurality of cylinders,
Crank angle detection means for detecting the crank angle of the engine;
Reference position detection means for detecting a reference position set at a predetermined crank angle;
Engine control means for starting fuel injection control and ignition control based on the reference position detected by the reference position detection means at the first reference position detected by the reference position detection means after the start of rotation of the engine;
Stop crank angle detection means for detecting a crank angle at the time of rotation stop of the engine based on a detection result by the crank angle detection means;
Pre-injection cylinder discriminating means in which at least the initial stage of the intake stroke is included between the stop crank angle detected by the stop crank angle detecting means and the next reference position following the stop crank angle is a pre-injection cylinder; With
The engine control means injects fuel into the preliminary injection cylinder after the start of rotation of the engine and before the first reference position is detected, and until the first reference position is detected. Is an engine control device characterized by not performing ignition control.

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