JP2005320945A - Engine control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems such as deterioration of emission in starting an engine by properly performing the discrimination of cylinders. <P>SOLUTION: A crank angle sensor 12 outputs crank signals formed of pulse rows at prescribed angular intervals according to the rotation of the crankshaft of a multi-cylinder engine. An ECU 10 determines a crank position based on the crank signals by the crank angle sensor 12 and stores, as engine stop position information, the crank position in stopping the engine. Also, the ECU 10 monitors the crank signals by the crank angle sensor 12 in stopping the engine and stores, as the engine stop position information, the history of the variation of a crank angle output. In addition, the ECU 10 performs, in starting the engine, the discrimination of the cylinders based on the engine stop position information stored in stopping the engine and during the stoppage of the engine. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine control apparatus, and more particularly to a technique that can satisfactorily perform cylinder discrimination when starting an engine.

  As this type of prior art, for example, Patent Literatures 1, 2, and 3 are known. In each of these patent documents, the crank angle position when the engine is stopped is stored, and at the next engine start, the cylinder is determined based on the crank angle position when the engine is stopped and the fuel is determined based on the cylinder determination result. I am trying to spray.

Each of the above technologies aims to improve the start response by quickly determining the cylinder when starting the engine. However, if the crankshaft rotates unexpectedly while the engine is stopped, the cylinder will be The accuracy of discrimination is reduced. In this case, if cylinder discrimination is performed erroneously, for example, fuel is injected into the cylinder immediately before or after the original injection cylinder, and as a result, emission may be deteriorated due to discharge of unburned gas. was there. Further, there arises a disadvantage that the start-up response cannot be improved as desired.
JP-A-60-240875 JP 05-332177 A Japanese Patent Application Laid-Open No. 07-083093

  The main object of the present invention is to provide an engine control device that can perform appropriate cylinder discrimination and, in turn, solve problems such as emission deterioration at the time of engine start.

  According to the first aspect of the present invention, when the crankshaft of the multi-cylinder engine rotates, a crank signal composed of a pulse train at predetermined angular intervals is output from the crank signal output means. Then, the crank position is determined based on the crank signal, and when the engine is stopped, the determined crank position is stored as engine stop position information. Further, when the engine is stopped, the crank signal is monitored by the crank signal output means, and the change history of the crank signal output is stored as engine stop position information. Further, when the engine is started, cylinder discrimination is performed based on the engine stop position information stored when the engine is stopped and while the engine is stopped.

  In short, even if the engine stop position information is stored when the engine is stopped in preparation for cylinder discrimination at the next engine start, the crankshaft is reversed immediately before the engine is stopped, or the crankshaft rotates unexpectedly while the engine is stopped. Then, cylinder discrimination at the time of engine start cannot be performed correctly. On the other hand, according to the above configuration, since the crank signal is monitored even when the engine is stopped, it is possible to cope with unexpected rotation of the crankshaft and to perform proper cylinder discrimination. As a result, problems such as emission deterioration at engine start-up are also solved. Further, according to the above configuration, cylinder discrimination can be performed from the beginning of rotation at the time of engine start, and engine startability can be improved.

  Here, the crank signal output means outputs a crank signal continuously even after the engine is stopped (Claim 9). For example, the detection is based on the rotating body having gear teeth on the outer periphery and the rotational position of the rotating body. A magnetic sensor having a magnetoresistive element whose resistance value changes in accordance with the direction of the magnetic field and that can detect reverse rotation of the crankshaft. The cam signal output means described later is also equivalent.

  According to the second aspect of the invention, when the engine is stopped, the engine stop position information stored when the engine is stopped is updated based on the crank signal output during the engine stop. When the engine is started, cylinder discrimination is performed based on the updated engine stop position information. In this case, the engine stop position information stored when the engine is stopped is updated as needed, but even with this configuration, appropriate cylinder discrimination can be performed as described above.

  According to the third aspect of the present invention, since the timing at which the cam signal mode is switched is synchronized with the injection timing for each cylinder, after the engine is started, the first fuel is switched at the cam signal mode switching immediately after the cylinder discrimination is completed. Injection can be performed. In this case, the timing at which the cam signal mode is switched may be synchronized with the most retarded injection timing for each cylinder (the limit position where intake combustion is possible). Thereby, fuel injection can be started as soon as the engine is started, and the engine startability is improved.

  By monitoring the crank signal while the engine is stopped as described above, it is possible to cope with unexpected rotation of the crankshaft.However, due to steep rotation, etc., the detection of crankshaft rotation is missed and the engine stop position information is correct. There is also a case where it is not memorized. As a guarantee, in the invention according to claim 4, when the engine is stopped, the cam signal mode is stored together with the crank position as engine stop position information, while the cam signal mode is recorded together with the change history of the crank signal output while the engine is stopped. A history of changes is stored, and further, at the time of engine start, execution of cylinder discrimination is permitted or prohibited based on the cam signal mode stored so far and the actual cam signal mode at that time.

  In this case, when the crankshaft rotates while the engine is stopped and the first injection cylinder at the next engine start changes, the cam signal mode changes accordingly. If the actual crankshaft rotation is correctly detected based on the crank signal output, the cam signal mode change history is stored as engine stop position information. The history of cam signal mode changes is not stored. Therefore, a cam signal mode mismatch (a mismatch between the stored contents and the actual one) occurs when the engine is started. By prohibiting cylinder discrimination due to this cam signal mode mismatch, it is possible to avoid the inconvenience that fuel injection is erroneously performed on a cylinder other than the original injection cylinder.

  In the invention according to claim 5, the cam signal output means outputs a cam signal in which a low level (L level) period and a high level (H level) period are individually set for each combustion cylinder. When the engine is started, cylinder discrimination is permitted or prohibited by matching the cam signal level stored so far as the engine stop position information with the cam signal level at the time of starting. In this case, in order to confirm the consistency of the cam signal mode, the cam signal level may be confirmed, and the cam signal mode can be easily confirmed.

  In the invention described in claim 6, as cylinder discrimination means, first discrimination means for performing cylinder discrimination based on the engine stop position information, and cylinder discrimination based on the detection result of the reference position information of the crank signal. Second discrimination means to be implemented is provided. Then, after the engine is started, the cylinder discrimination by the first discrimination means is performed on the condition that the cylinder discrimination by the second discrimination means is not completed. That is, comparing the cylinder discrimination performed based on the engine stop position information and the cylinder discrimination performed based on the detection result of the reference position information of the crank signal, the former is superior in terms of early implementation after engine start. The latter is superior from the viewpoint of accuracy and reliability. Considering this, it is desirable that the cylinder discrimination by the first discrimination means is performed only when the cylinder discrimination by the second discrimination means is not completed. In this case, since cylinder discrimination is performed in two systems, the reliability of cylinder discrimination is improved, and reliable fuel injection can be performed.

  When the cylinder is discriminated by the second discriminating means, the cam signal mode (L / H level of the cam signal, etc.) is used in combination as the cylinder discriminating information, so that reliable cylinder discrimination can be achieved even when the number of engine cylinders increases. Can be implemented.

  Although it does not occur originally, when the cylinder discrimination result by the first discrimination means and the cylinder discrimination result by the second discrimination means are inconsistent, the fuel implemented based on the former cylinder discrimination result There is a possibility that the injection is an erroneous injection and the injected fuel stays in the intake port or the like. Therefore, as a measure in the event that an error occurs in the first discriminating means, as described in claim 7, there is an inconsistency in the cylinder discriminating result, and the cylinder discriminating result by the first discriminating means If fuel injection has already been performed based on this, the next injection amount to the injection cylinder may be corrected to the reduction side.

  In an engine having an automatic stop / automatic start function, the engine is automatically stopped by waiting for a signal or a railroad crossing, and then restarted. In such a case, it is necessary to improve the engine startability in order to ensure the start response of the vehicle. However, as described above, the cylinder discrimination can be optimized, and a desired effect can be achieved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the present embodiment, an engine control system is constructed for an on-vehicle multi-cylinder gasoline engine. In the control system, an electronic control unit (hereinafter referred to as ECU) is used as a center to control the fuel injection amount and the ignition timing. Control etc. is to be implemented.

  FIG. 1 is a block diagram showing the main configuration of the present control system. The ECU 10 is configured around a known microcomputer including a CPU, ROM, RAM, and the like. The ECU 10 includes a load sensor (for example, an intake pipe pressure sensor and an air flow meter) 11, a crank angle sensor 12, and a cam angle sensor. 13. Various detection signals are input from the vehicle speed sensor 14, the brake switch 15, and the like. The ECU 10 executes various control such as fuel injection by the injector 21 and ignition timing by the ignition device 22 according to the engine operating state by executing a control program prepared in advance based on various detection signals input from each sensor or the like. carry out.

  The ECU 10 performs idle stop control (engine automatic stop / automatic start control) for the purpose of reducing fuel consumption, reducing exhaust emissions, and reducing noise. In this idle stop control, for example, the engine is automatically stopped when the driver depresses the brake pedal to stop the vehicle, and then the engine is automatically activated when the driver releases the brake pedal depressing operation. It is supposed to be restarted.

  Here, the crank angle sensor 12 outputs a number of pulsed crank signals as the crankshaft rotates, and the cam angle sensor 13 varies in logic level according to the rotational position of the camshaft as it rotates. In particular, in the present embodiment, the engine rotation information is detected using a magnetoresistive element (hereinafter referred to as MRE) whose resistance value changes due to a change in magnetic vector. The crank angle sensor 12 corresponds to “crank signal output means”, and the cam angle sensor 13 corresponds to “cam signal output means”.

  FIG. 2 shows the configuration of the crank angle sensor 12 and the cam angle sensor 13. As shown in FIG. 2A, the crank angle sensor 12 includes a rotor (rotating body) 32 fixed to the crankshaft 31 of the engine and a magnetic detection unit provided so as to face the outer peripheral surface of the rotor 32. 33. A large number of gear teeth 32 a are formed on the outer peripheral surface of the rotor 32. The gear teeth 32a are basically provided at intervals of 10 ° CA, and reference position detectors are provided at two locations along the gear teeth 32a. In the present embodiment, a reference position detection unit K1 in which two gear teeth 32a are missing and a reference position detection unit K2 in which three gear teeth 32a are integrated are provided. Located 180 ° CA apart. Hereinafter, for convenience of explanation, K1 is referred to as a first missing tooth portion, and K2 is referred to as a second missing tooth portion. The magnetic detection unit 33 includes a plurality of MREs and bias magnets, and a crank signal is output from the magnetic detection unit 33 as the rotor 32 rotates.

  As shown in FIG. 2B, the cam angle sensor 13 includes a rotor (rotary body) 42 fixed to the cam shaft 41 of the engine, and a magnet provided so as to face the outer peripheral surface of the rotor 42. And a detector 43. As is well known, the camshaft 41 rotates once for every two rotations (720 ° CA) of the crankshaft 31. Three long teeth 42 a are formed on the outer peripheral surface of the rotor 42 so as to extend long in the outer peripheral direction. In this case, assuming that the three long teeth 42a and the interval between the teeth are A, B1, B2, C, D1, and D2, the intervals between these sections are A = 90 ° (180 ° CA) and B1 = 30. ° (60 ° CA), B2 = 60 ° (120 ° CA), C = 90 ° (180 ° CA), D1 = 30 ° (60 ° CA), D2 = 60 ° (120 ° CA) . The magnetic detection unit 43 includes a plurality of MREs and bias magnets, and a cam signal is output from the magnetic detection unit 43 as the rotor 42 rotates.

  By configuring the crank angle sensor 12 and the cam angle sensor 13 as magnetic sensors using MRE as described above, unlike the magnetic pickup type rotation sensor, either L / H signal output is possible even when the engine is stopped. Even if the crankshaft or camshaft rotates while the engine is stopped, the rotation is detected at any time.

  Next, signal forms of the crank signal and the cam signal will be described with reference to FIG. In the present embodiment, an example of a four-cylinder engine is shown, and the combustion order is the first cylinder (# 1) → the third cylinder (# 3) → the fourth cylinder (# 4) → the second cylinder. (# 2). In the figure, # 1, # 2, # 3, and # 4 with ▽ indicate the compression TDC positions of the first to fourth cylinders, respectively.

  The crank signal basically consists of a pulse train having an interval of 10 ° CA, and the first missing tooth portion K1 and the second missing tooth portion K2 are detected in the middle of the crank signal. In this case, the first missing tooth portion K1 is detected as an L level signal with two pulses missing, and the second missing tooth portion K2 is detected as an H level signal for three pulses. The crank counter ccrnk is for determining the crank position, and is counted up in accordance with the pulse edge of the crank signal. The crank counter ccrnk is incremented every 10 ° CA in the range of 0 to 71 with # 1 TDC being 0.

The cam signal changes at the L / H level for each section of A, B1, B2, C, D1, and D2 within one rotation of the camshaft (720 ° CA). In this case, the edge timing of the cam signal and the injection timing of each cylinder are synchronized, specifically,
The cam edge that transitions from the A section to the B1 section is the injection timing of the second cylinder,
The cam edge that transitions from the B2 section to the C section is the injection timing of the first cylinder,
The cam edge that transitions from the C section to the D1 section is the injection timing of the third cylinder,
The cam edge that transitions from the D2 section to the A section is the injection timing of the fourth cylinder,
It has become. The injection timing of each cylinder is ATDC 60 ° CA of intake TDC. In this embodiment, the fuel injection of each cylinder is started at the above injection timing. However, the timer is set at the same injection timing, and the fuel injection of each cylinder is started after the set time has elapsed. It may be a configuration.

  The ECU 10 that handles the crank signal and the cam signal described above performs cylinder discrimination based on these signals at the initial start of the engine (when the IG is on) and at the restart after the idle stop. That is, at the time of engine start (including restart), the arrival of the first and second missing tooth portions K1, K2 is detected based on the pulse interval of the crank signal, and the signal level at the time of detecting the missing tooth portion is The first and second missing tooth portions K1 and K2 are specified by L or H. At this time, the interval (pulse interval) from the previous edge is measured for each rising edge of the crank signal, and the ratio (= current value / previous value) between the previous value and the current value of the pulse interval is a predetermined value (for example, 2. If it is larger than 5), the fact that it is the first and second missing tooth portions K1, K2 is detected. Further, it determines each section of the cam signal each time depending on whether the cam signal level at the time of detecting each missing tooth portion is L or H, and the next injection cylinder is determined from the determination result.

In particular,
If the first missing tooth portion K1 is detected and the cam signal = L at that time, it is determined that it is the A section, and thereby the second cylinder is the next injection cylinder.
If the second missing tooth portion K2 is detected and the cam signal is L at that time, it is determined that the section is the B2 section, and thereby the first cylinder is determined as the next injection cylinder.
-If the 1st missing tooth part K1 is detected and the cam signal = H at that time, it will discriminate | determine that it is C area, and this will make the 3rd cylinder the next injection cylinder.
-If the 2nd missing tooth part K2 is detected and the cam signal = H at that time, it will discriminate | determine that it is D2 area, and this will make the 4th cylinder the next injection cylinder.

  On the other hand, when the engine is started, it is possible to detect a period during which the L level or H level continues in the cam signal, and to determine which section of the cam signal each time according to the period length. Then, cylinder discrimination is performed based on the result, and the next injection cylinder is determined from the discrimination result.

In particular,
If the L period of the cam signal is 180 ° CA, it is determined that it is the A section, and the second cylinder is thereby determined as the next injection cylinder.
If the H period of the cam signal is 60 ° CA, it is determined that it is the B1 section, whereby the first cylinder is determined to be the next injection cylinder.
If the L period of the cam signal is 120 ° CA, it is determined that it is the B2 section, whereby the first cylinder is determined to be the next injection cylinder.
If the H period of the cam signal is 180 ° CA, it is determined that it is the C section, whereby the third cylinder is determined as the next injection cylinder.
If the L period of the cam signal is 60 ° CA, it is determined that it is the D1 section, and the fourth cylinder is thereby determined as the next injection cylinder.
If the H period of the cam signal is 120 ° CA, it is determined that it is the D2 section, and the fourth cylinder is thereby determined as the next injection cylinder.

  The cylinder discrimination method based on the detection of the missing tooth portion of the crank signal and the cylinder discrimination method based on the detection of the L / H period of the cam signal can each perform appropriate cylinder discrimination. However, with these cylinder discrimination methods, the engine rotates to some extent. Thus, the cylinder discrimination is awaited until the missing tooth portion of the crank signal or the L / H period of the cam signal is detected. Therefore, in the present embodiment, the engine stop position state is monitored from the previous engine stop to the next engine start so that the cylinder can be discriminated immediately after the initial rotation is applied at the time of engine start. At the time of starting, cylinder discrimination is performed based on the engine stop position information.

  That is, when the engine is stopped, the value of the crank counter ccrnk and the L / H level of the cam signal are stored in the RAM or the like as engine stop position information. Further, even when the engine is stopped, the rotation of the crankshaft is monitored by detecting the edge of the crank signal, and when the occurrence of rotation is detected, the crank counter ccrnk is updated and the L / H level of the cam signal at that time is detected. Stop position information is stored in a RAM or the like. Then, when the engine is started, the first injection cylinder is determined based on the engine stop position information stored in the RAM or the like.

  This will be described more specifically with reference to FIG. In FIG. 4, for example, consider a case where the state when the engine is stopped is P1, and the crankshaft rotates for some reason and then shifts to the state of P2 while the engine is stopped (including idle stop). In this case, the engine stop position information when the engine is stopped is ccrnk = 17 and the cam signal level = L. Then, by monitoring the crankshaft rotation (transition to the P2 state) while the engine is stopped, the engine stop position information becomes ccrnk = 22 and the cam signal level = L when the engine is started, and based on the engine stop position information. The cylinder is discriminated. In this example, the second cylinder is assumed to be the next injection cylinder.

  However, there may be a case where the actual crankshaft rotation cannot be detected by the crank angle sensor 12 and the crank counter ccrnk cannot be updated due to a steep rotation or the like. As a countermeasure, it is determined whether or not the engine stop position information can be used for cylinder discrimination by matching the L / H level of the cam signal when the engine is started. For example, if the L / H level of the cam signal updated while the engine is stopped is L, but the actual cam signal at the time of engine start is H level, cylinder discrimination based on the engine stop position information is prohibited. To do.

  Even when the crankshaft rotates while the engine is stopped and shifts to the state of P3, that is, when the L / H level of the cam signal is different between when the engine is stopped and when the next engine is started, the engine is stopped while the engine is stopped. As the stop position information is updated as needed, cylinder discrimination can be performed in the same manner as described above.

  Regarding the detection of the L / H period of the cam signal, when the engine is started from the state of P2 as described above, the B1 section of the cam signal is first detected after the start. The first cylinder is determined to be the next injection cylinder by detecting the B1 section.

  Further, regarding the detection of the missing tooth portion of the crank signal, when the engine is started from the state of P2 as described above, after the start, detection is performed in the order of the second missing tooth portion K2 and the first missing tooth portion K1. Since crankshaft rotation is unstable immediately after engine startup (during cranking rotation), cylinder discrimination is made based on detection of missing teeth for the second time after startup (K1 detection before # 2 TDC in this example). desirable. Therefore, when the missing tooth portion K1 is detected, since the cam signal is H, the C section is detected, and the third cylinder is assumed to be the next injection cylinder.

  Here, comparing (1) cylinder discrimination based on engine stop position information, (2) cylinder discrimination based on cam signal L / H period detection, and (3) cylinder discrimination based on crank signal missing tooth detection, comparison is made after engine startup. The possible order is considered to be (1) → (2) → (3), but the cylinder discrimination accuracy is considered to be (3) → (2) → (1). Therefore, in the present embodiment, the cylinders (1) and (2) are assumed to be provisional discrimination, and the cylinder discrimination (3) is handled as the main discrimination. That is, the cylinder discrimination result is prioritized in the order of (3) → (2) → (1).

  The ignition cylinder discrimination is performed on the assumption that the cylinder discrimination is performed by detecting the missing tooth portion of the crank signal. In this case, in the case of port injection, there is an interval of about 300 ° CA from the injection timing (intake ATDC 60 ° CA) to ignition, and it is considered that the missing tooth detection is executed twice during that time. It is considered that there is no problem even if it does not depend on the result of cylinder discrimination by cylinder discrimination or cam signal L / H period detection.

  In the event that cylinder discrimination by missing tooth detection is not completed at the ignition timing, so-called backup ignition is performed in which ignition is performed at or near the compression TDC with reference to the edge of the cam signal. May be.

  Next, the cylinder discrimination procedure of the ECU 10 at the time of engine restart after idle stop will be described. FIG. 5 is a flowchart showing stop position storage processing while the engine is stopped, and FIGS. 6 and 7 are flowcharts showing cylinder discrimination processing when the engine is restarted.

  Now, the processing of FIG. 5 is started by the ECU 10 at every rising edge of the crank signal, and in step S101, it is determined whether or not the engine is stopped due to idle stop. Then, the process proceeds to step S102 on condition that the engine is stopped, and the engine stop position information at that time is stored. In other words, the edge of the crank signal was detected even when the engine was stopped, because an unexpected rotation occurred on the crankshaft, and the value of the crank counter ccrnk was updated to update the engine stop position information. This is stored in the RAM or the like, and the cam signal level at that time is detected and stored in the RAM or the like as CLr. At this time, if the crankshaft has rotated in the forward direction this time, the crank counter ccrnk is incremented by 1, and if it has rotated in the reverse direction, the crank counter ccrnk is decremented by 1.

  6 and 7 is started by the ECU 10 at every rising edge of the crank signal in accordance with an engine start command (for example, release of brake depression) after idling stop. After the start, first, in step S201, it is determined whether or not engine stop position information (crank counter ccrnk, cam signal level CLr) is stored in the RAM or the like. In the case of NO, the process proceeds to step S202, where it is determined that the temporary injection condition is not satisfied, the temporary injection condition satisfaction flag FI is turned off, and then this process is terminated.

  If step S201 is YES, it will progress to step S203 and it will be discriminate | determined whether this process is a first process after a start command. If this is the first time processing, the cam signal level CL at that time is detected in step S204, and whether or not the cam signal level CL matches the cam signal level CLr stored in the RAM or the like in subsequent step S205. Is determined. If CL = CLr, the temporary injection condition satisfaction flag FI is turned on in step S206. If CL ≠ CLr, the temporary injection condition satisfaction flag FI is turned off in step S207.

  If this time is not the first process, the process proceeds to step S208 in FIG. 7 to determine whether or not the cylinder determination is completed in another missing tooth detection process. If step S208 is YES, steps S209 to S213 are skipped and the process proceeds directly to step S214.

  If NO in step S208, it is determined in step S209 whether the injection timing of the next injection cylinder is the first cam edge or the second cam edge in the future based on the stored information of the engine stop position. For example, if the engine stop position is the A, B2, C, D2 section of the cam signal (see FIG. 3), the first cam edge is the injection timing, and the engine stop position is the B1, D1 section of the cam signal (see FIG. 3). ), The second cam edge is the injection timing. In the former case, on the condition that the first cam edge is detected and the temporary injection condition satisfaction flag FI = ON, fuel injection is performed on the corresponding cylinder based on the stored information of the engine stop position (Step S210, S212, S213). In the latter case, on the condition that the second cam edge is detected and the temporary injection condition satisfaction flag FI = ON, fuel injection is performed on the corresponding cylinder based on the stored information of the engine stop position (step S211, S212, S213).

  Thereafter, in step S214, it is determined whether or not fuel injection has been performed based on the stored information of the engine stop position. In the case of YES, after determining that the detection of the missing tooth portion of the crank signal is completed in step S215, in step S216, the cylinder based on the cylinder discrimination result based on the stored information of the engine stop position and the detection of the missing tooth portion of the crank signal. It is determined whether or not the determination result is consistent. If they match, the process is terminated as it is. If not, the process proceeds to step S217, and the next injection amount to the injection cylinder that has already been performed is corrected based on the stored information of the engine stop position. For example, the next injection amount is corrected to decrease.

  When step S214 is NO, in step S218, the first fuel injection is performed by cylinder discrimination based on the detection of the missing tooth portion of the crank signal.

  6 and 7, the cylinder discrimination procedure at the time of engine restart after idle stop has been described, but the same cylinder discrimination is also performed at the initial start of the engine accompanying the ON operation of the ignition switch (IG switch). . In this case, the engine stop position may be monitored after the engine is stopped (after the IG is turned off) so that the engine stop position information can be confirmed when the engine is started. Or it is good also as a structure which monitors an engine stop position for the predetermined period which has an emission reduction effect. For example, it is conceivable that the power supply to the ECU 10 is continued even after the IG is turned off and the detection operation of the crank angle sensor 12 and the cam angle sensor 13 is continued.

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

  The crank signal and the cam signal are monitored even when the engine is stopped, and the cylinder discrimination at the time of starting the engine is performed based on the monitoring result (the crank counter ccrnk, which is the engine stop position information, the cam signal level). This makes it possible to cope with unexpected rotations and to perform proper cylinder discrimination. As a result, problems such as emission deterioration at engine start-up are also solved. In addition, cylinder discrimination can be performed from the beginning of rotation at the time of engine start, and engine startability can be improved.

  In addition, when the engine is started, cylinder discrimination is performed on the condition that the RAM value of the cam signal level (cam signal mode) matches the actual state. Therefore, even if a crankshaft rotation detection omission occurs. Thus, it is possible to avoid the inconvenience that fuel injection is erroneously performed in a cylinder other than the original injection cylinder.

  The excellent effect can be realized by one crank angle sensor 12 and one cam angle sensor 13 as in the current system. Therefore, the configuration is not complicated and the cost is not increased. If another device such as a resolver capable of detecting the absolute position of the crank angle is used, the desired effect can be obtained without updating the engine stop position information while the engine is stopped, but this greatly changes the current system. Inconvenience such as cost increase occurs. However, this inconvenience does not occur.

  The cam signal output from the cam angle sensor 13 is synchronized with the timing of its edge and the injection timing of each cylinder. Therefore, after the engine is started, the first fuel at the first or second cam edge after cylinder discrimination is completed. Injection can be performed. Thereby, fuel injection can be started as soon as the engine is started, and the engine startability is improved.

  In an engine having an idle stop function (automatic stop / automatic start function), it is necessary to improve engine startability in order to ensure vehicle start-up response. The effect is achieved. By improving the engine startability, it is possible to reduce the load on the starter (such as a starter motor).

  In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

  In the above embodiment, when the engine is stopped, the engine stop position information (crank counter ccrnk, cam signal level) stored when the engine is stopped is updated as needed, and when the engine is started, cylinder discrimination is performed based on the latest update result. Changes this configuration. For example, when the engine is stopped, the number of output pulses of the crank signal (the number of forward rotation pulses and the number of reverse rotation pulses) is stored as the history of changes in the crank signal output, and the number of cam edge straddles is recorded as the history of changes in the cam signal output. When the engine is started, cylinder discrimination is performed based on the engine stop position information stored when the engine is stopped and the history. Even with this configuration, appropriate cylinder discrimination at the time of engine start can be realized as described above.

  In the above embodiment, the cylinder discrimination method at the time of engine start includes (1) cylinder discrimination based on engine stop position information, (2) cylinder discrimination based on detection of the L / H period of the cam signal, and (3) lack of the crank signal. The cylinder discrimination based on the tooth detection is performed, but at least (1) is selected among them. In order to maintain cylinder discrimination accuracy, (1) and (3) may be performed.

  Further, when the cam edge over which the stop position range LT extends is not the injection timing of each cylinder, the fuel injection in the intake stroke is in time even if the cam signal level mismatch occurs. Therefore, the cylinder corresponding to the next cam edge (cam edge at the injection timing) is set as the injection cylinder.

  However, when the stop position range LT extends over two or more cam edges, there is a high possibility that alignment with the actual crank position cannot be achieved, and therefore cylinder discrimination and fuel injection are prohibited.

It is a block diagram which shows the outline of the engine control system in embodiment of invention. It is a figure which shows the structure of a crank angle sensor and a cam angle sensor. It is a time chart for demonstrating the signal form of a crank signal and a cam signal. It is a time chart for demonstrating the signal form of a crank signal and a cam signal. It is a flowchart which shows an engine stop position storage process. It is a flowchart which shows a cylinder discrimination | determination process. FIG. 7 is a flowchart illustrating cylinder discrimination processing following FIG. 6.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... ECU, 12 ... Crank angle sensor, 13 ... Cam angle sensor, 31 ... Crankshaft, 42 ... Camshaft

Claims (9)

A crank signal output means for outputting a crank signal composed of a pulse train at predetermined angular intervals as the crankshaft of the multi-cylinder engine rotates.
Crank position determination means for determining a crank position based on a crank signal from the crank signal output means;
First storage means for storing the crank position determined by the crank position determination means when the engine is stopped as engine stop position information;
Second storage means for monitoring a crank signal by the crank signal output means while the engine is stopped, and storing a history of changes in the crank signal output as engine stop position information;
Cylinder discrimination means for performing cylinder discrimination based on engine stop position information stored by the first storage means and the second storage means at the time of engine start;
An engine control device comprising:   The second storage means updates the engine stop position information stored when the engine is stopped by the first storage means based on a crank signal output during engine stop, and the cylinder determination means is configured to update the engine stop position. The engine control apparatus according to claim 1, wherein cylinder discrimination is performed based on position information. Cam signal output means for outputting different cam signals for each successive combustion cylinder according to the rotation of the camshaft of the engine;
The engine control device according to claim 1 or 2, wherein a timing at which the cam signal is switched is synchronized with an injection timing for each cylinder.   When the engine is stopped, the first storage means stores the cam signal mode together with the crank position as engine stop position information, while the second storage means stores the cam signal together with the change history of the crank signal output while the engine is stopped. 4. A mode change history is stored, and further, at the time of engine start, execution of cylinder discrimination by the cylinder discrimination means is permitted or prohibited based on a cam signal mode stored so far and an actual cam signal mode at that time. The engine control device described in 1.   The cam signal output means outputs a cam signal in which a low level period and a high level period are individually set for each combustion cylinder, and stored as the engine stop position information so far when the engine is started. 5. The engine control device according to claim 4, wherein execution of cylinder discrimination is permitted or prohibited by matching between the cam signal level and the cam signal level at the start. In the engine control device configured so that the crank signal output means outputs a crank signal having at least one reference position information in the middle of the pulse train,
The cylinder determining means includes a first determining means for performing cylinder determination based on the engine stop position information, and a second determining means for performing cylinder determination based on the detection result of the reference position information. ,
The engine control according to any one of claims 1 to 5, wherein after the engine is started, cylinder discrimination by the first discrimination means is performed on the condition that cylinder discrimination by the second discrimination means is not completed. apparatus.   It is determined whether or not the cylinder discrimination result by the first discrimination means matches the cylinder discrimination result by the second discrimination means, and the cylinder discrimination results are inconsistent, and the first discrimination means The engine control apparatus according to claim 6, wherein if fuel injection has already been performed based on a cylinder discrimination result, the next injection amount to the injection cylinder is corrected to a reduction side.   It has an automatic stop / automatic start function that automatically stops the engine when a predetermined automatic stop condition is satisfied during engine operation and automatically starts the engine when a predetermined automatic start condition is satisfied during automatic engine stop. The engine control device according to any one of claims 1 to 7.   The engine control device according to any one of claims 1 to 8, wherein the crank signal output means outputs a crank signal continuously even after the engine is stopped.

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