JP2007032459A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

To increase torque by ignition advance without causing reverse rotation of the engine at the time of engine start.
When starting an engine, when each cylinder reaches TDC (compression top dead center), when the engine speed ne exceeds 400 rpm at the timing of BTDC 20 ° (step ST2), or at the timing of BTDC 10 °. When the engine speed ne exceeds 200 rpm (step ST3), it is determined that ignition advance is possible, and ignition is immediately performed at the timing BTDC 20 ° or BTDC 10 ° to advance the ignition. By such ignition timing control, even when the engine speed ne fluctuates drastically at the time of starting, an increase in torque at the time of starting can be achieved while avoiding reverse rotation of the engine.
[Selection] Figure 3

Description

  The present invention relates to an ignition timing control device for an internal combustion engine mounted on a vehicle or the like.

  As an internal combustion engine (hereinafter also referred to as an engine) mounted on a vehicle or the like, there are a port injection engine and an in-cylinder direct injection engine.

  A port injection engine injects fuel into an intake port from a fuel injection valve (injector) disposed in an intake port of each cylinder, mixes the injected fuel and intake air, introduces the mixture into a combustion chamber, and introduces the introduced air-fuel mixture. This is an engine that ignites (fuel + air) with a spark plug.

  An in-cylinder direct injection engine has a fuel injection valve in each cylinder, and fuel such as gasoline is directly injected into the combustion chamber from the fuel injection valve and mixed with intake air introduced from the intake port into the combustion chamber. This is an engine that forms an air-fuel mixture and ignites the air-fuel mixture with a spark plug. In-cylinder direct-injection engines are rapidly increasing in demand because of their excellent fuel efficiency, low exhaust emissions, and high output.

In a port injection engine and an in-cylinder direct injection engine, various controls are performed to advance the ignition timing at the start. For example, the ignition timing is advanced from the MBT (minimum ignition advance) to improve the engine warm-up (for example, see Patent Document 1), or the engine speed is at a predetermined level (for example, 600 rpm). There is an ignition timing control method for reducing emission by selecting an ignition advance angle of 20 ° BTDC (before compression top dead center) when a predetermined condition is established for the cooling water temperature or the like in the start mode that is less than (for example, Patent Document 2).
JP 2000-240547 A Japanese Patent Application Laid-Open No. 9-100769

  By the way, in a low temperature start of a direct injection engine in a cylinder, when starting with a lean misfire due to insufficient fuel injection period, usually the ignition timing is fixed to compression top dead center (hereinafter also referred to as TDC) or BTDC 5 ° Ignition is in progress. The reason for this will be explained. Since the engine speed fluctuates drastically at the start with lean misfire (see FIG. 5), the ignition advance is possible when the engine speed is high at the time of ignition, but the engine speed is low. In the case of the rotation speed (for example, 400 rpm or less), there is a possibility that the piston is pushed back by the combustion due to the ignition of the advance angle and the engine rotates backward, and hard ignition is performed to avoid this. When hard ignition is applied at the time of low temperature start in this way, torque increase due to ignition advance cannot be performed even though there is an increase in engine speed (for example, exceeding 400 rpm) that can be expected to increase torque at start-up. There is a problem.

  Here, in the ignition timing control of a direct injection engine or the like in the cylinder, for example, ignition timing (soft ignition) is performed by calculating the ignition timing based on the operating state such as the engine speed at the timing of BTDC 90 °. Although it is conceivable to perform ignition advance at low temperature start by soft ignition, in this case, the following problems occur.

  That is, as described above, in the direct injection engine, when the engine is started at a low temperature with a lean misfire at a low temperature, the engine speed fluctuates violently, so the engine speed exceeds 400 rpm at the timing of BTDC 90 °. However, at the actual ignition timing, the engine speed may decrease and the engine speed may be 400 rpm or less, and if the ignition is advanced in such a situation, the reverse rotation of the engine occurs. There's a problem.

  The above-mentioned problems are not limited to direct-in-cylinder direct injection engines, and the same can be said for port injection engines because the engine speed may fluctuate due to misfire or the like during cold start. In addition, the engine speed may fluctuate during normal start-up as well as during low-temperature start-up, and the same problem occurs.

  Note that the techniques described in Patent Documents 1 and 2 do not take into account that the engine speed fluctuates due to lean misfire or the like at the time of cold start of the engine. Even if the technology is used, an increase in torque cannot be achieved while avoiding reverse rotation of the engine at a low temperature start or the like.

  The present invention has been made in consideration of such circumstances, and can achieve a torque increase by ignition advance without causing reverse rotation of the internal combustion engine at the time of starting, and can obtain a good startability. It is an object to provide an ignition timing control device for an internal combustion engine.

  The present invention relates to an ignition timing control device for controlling the ignition timing of an internal combustion engine that ignites and burns an air-fuel mixture with an ignition plug, and at the start of the internal combustion engine, a predetermined crank before the compression top dead center of each cylinder. An engine timing is detected by an angle, and an ignition timing control means for igniting at a predetermined crank angle before the compression top dead center is provided for a cylinder whose engine speed exceeds a predetermined determination value. It is characterized by that.

  According to the present invention, at the start of the internal combustion engine, when each cylinder reaches the compression top dead center, the engine speed is a predetermined determination value (specifically, the internal combustion engine at a predetermined crank angle before the compression top dead center). When the engine speed exceeds (the speed at which the engine does not rotate reversely), it is determined that ignition advance is possible, and ignition is performed at the crank angle before the compression top dead center to advance the ignition. Even when the engine speed fluctuates drastically, an increase in torque can be achieved by utilizing the increase in engine speed while avoiding reverse rotation of the internal combustion engine.

  A specific configuration of the present invention will be described below.

  In the present invention, the engine speed is detected at two different crank angles before the compression top dead center, and the engine speed detected at the first crank angle on the advance side of the two crank angles is the first. Ignition is performed when the determination value of 1 is exceeded, and the engine speed detected at the second crank angle on the compression top dead center side exceeds the second determination value that is smaller than the first determination value. You may comprise so that ignition may be implemented when it is.

  As described above, the torque can be increased more effectively by determining whether or not the ignition retard is possible at two different crank angles before the compression top dead center.

  Specifically, for example, ignition is performed when the engine speed at a crank angle of 20 ° before compression top dead center exceeds 400 rpm, and the engine speed at a crank angle of 10 ° before compression top dead center is set. Ignition is performed when the engine speed exceeds 200 rpm, so that ignition proceeds at a crank angle of 10 ° before compression top dead center even when ignition is not performed at a crank angle of 20 ° before compression top dead center. Since the angle can be implemented, it is possible to increase the torque by more effectively utilizing the increase in the engine speed at the start.

  According to the present invention, when the internal combustion engine is started, the engine speed is detected at a predetermined crank angle before the compression top dead center of each cylinder, and when the engine speed exceeds a predetermined determination value, the compression is performed. Since ignition is performed at a predetermined crank angle before the top dead center, torque increase due to ignition advance can be achieved without causing reverse rotation of the internal combustion engine at the time of starting, and startability can be improved. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, an engine (internal combustion engine) to which the present invention is applied will be described.

-Engine-
FIG. 1 is a diagram showing a schematic configuration of an engine to which the present invention is applied. FIG. 1 shows only the configuration of one cylinder of the engine.

  The engine 1 is an in-cylinder direct injection six-cylinder gasoline engine having six cylinders (cylinder # 1 to cylinder # 6), and includes a piston 10 that forms a combustion chamber 1a and a crankshaft 15 that is an output shaft. . The piston 10 is connected to the crankshaft 15 via a connecting rod 16, and the reciprocating motion of the piston 10 is converted into rotation of the crankshaft 15 by the connecting rod 16.

  A ring gear 17 is provided on the crankshaft 15. The ring gear 17 is engaged with a pinion gear 18 of a starter motor 7 that is started when the engine 1 is started, and the engine 1 is cranked by the rotation of the ring gear 17 when the starter motor 7 is started.

  A signal rotor 19 having a plurality of protrusions (teeth) 19 a... 19 a on the outer peripheral surface is attached to the crankshaft 15. A crank position sensor 35 is disposed near the side of the signal rotor 19. The crank position sensor 35 is, for example, an electromagnetic pickup, and generates a pulse signal (crank angle signal) corresponding to the protrusion 19a of the signal rotor 19 when the crankshaft 15 rotates. In this example, a crank angle signal is generated every time the crankshaft 15 rotates 30 ° CA.

  In the combustion chamber 1a of the engine 1, a spark plug 3 is disposed for each cylinder # 1 to # 6. The ignition timing of the spark plug 3 is adjusted by the igniter 4. The engine 1 is provided with a water temperature sensor 31 that detects the temperature (cooling water temperature) of the cooling water circulating in the water jacket 1b.

  An intake passage 11 and an exhaust passage 12 are connected to the combustion chamber 1 a of the engine 1. An intake valve 13 is provided between the intake passage 11 and the combustion chamber 1a. By opening and closing the intake valve 13, the intake passage 11 and the combustion chamber 1a are communicated or blocked. Further, an exhaust valve 14 is provided between the exhaust passage 12 and the combustion chamber 1a. By opening and closing the exhaust valve 14, the exhaust passage 12 and the combustion chamber 1a are communicated or blocked. The opening / closing drive of the intake valve 13 and the exhaust valve 14 is performed by each rotation of the intake camshaft 21 and the exhaust camshaft 22 to which the rotation of the crankshaft 15 is transmitted.

  A cylinder position determining cam position sensor 36 is disposed in the vicinity of the intake camshaft 21. The cam position sensor 36 is, for example, an electromagnetic pickup, and is disposed so as to face one protrusion (tooth) on the outer peripheral surface of the rotor provided integrally with the intake camshaft 21. Outputs a pulse signal when rotating. Since the intake camshaft 21 rotates at a half speed of the crankshaft 15, the cam position sensor 36 outputs one pulse-like signal (cylinder discrimination signal) every time the crankshaft 15 rotates 720 °. appear.

  A throttle valve 5 for adjusting the intake air amount of the engine 1 is disposed in the upstream portion of the intake passage 11. The throttle valve 5 is driven by a throttle motor 6. The opening degree of the throttle valve 5 is detected by a throttle position sensor 34. In the intake passage 11, a vacuum sensor 32 that detects the pressure (intake pressure) in the intake passage 11 is disposed downstream of the throttle valve 5. A three-way catalyst 8 is disposed in the exhaust passage 12 of the engine 1.

  The engine 1 is provided with an injector (fuel injection valve) 2 for directly injecting fuel into the combustion chamber 1a for each cylinder # 1 to # 6. High pressure fuel is supplied to the injector 2 of each cylinder, and fuel is directly injected into the combustion chamber 1a from each injector 2 to form an air-fuel mixture in which air and fuel are mixed in the combustion chamber 1a. The air-fuel mixture is ignited by the spark plug 3 and burned in the combustion chamber 1a. The piston 10 reciprocates due to the combustion of the air-fuel mixture in the combustion chamber 1a, and the crankshaft 15 rotates.

  The operating state of the engine 1 is controlled by an ECU (electronic control unit) 100.

-ECU-
As shown in FIG. 2, the ECU 100 includes a CPU 101, a ROM 102, a RAM 103, a backup RAM 104, and a crank counter (hereinafter referred to as a CA counter) 105.

  The ROM 102 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 101 executes arithmetic processing based on various control programs and maps stored in the ROM 102. The RAM 103 is a memory that temporarily stores calculation results of the CPU 101, data input from each sensor, and the like. The backup RAM 104 is a non-volatile memory that stores data to be saved when the engine 1 is stopped. is there. The ROM 102, CPU 101, RAM 103, backup RAM 104, and CA counter 105 are connected to each other via a bus 108 and to an external input circuit 106 and an external output circuit 107.

  A water temperature sensor 31, a vacuum sensor 32, an accelerator position sensor 33, a throttle position sensor 34, a crank position sensor 35, a cam position sensor 36, an ignition switch 37, and the like are connected to the external input circuit 106. The external output circuit 107 is connected to the injector 2, the igniter 4 of the spark plug 3, the throttle motor 6 of the throttle valve 5, the starter motor 7, and the like.

  Then, the ECU 100 determines the ignition timing of the spark plug 3 based on the outputs of various sensors such as the water temperature sensor 31, the vacuum sensor 32, the accelerator position sensor 33, the throttle position sensor 34, the crank position sensor 35, and the cam position sensor 36. Various controls of the engine 1 including control control (ignition instruction to the igniter 4) are executed. Further, the ECU 100 executes the following start-time fire timing control.

  Here, as shown in FIG. 4, the ECU 100 increments the CA counter 105 by one every time a crank angle signal is input from the crank position sensor 35 (that is, every time the crankshaft 15 rotates 30 ° CA), When a cylinder discrimination signal is input from the cam position sensor 36, the CA counter 105 is reset to “0”. In addition, the ECU 100 performs calculation for a crank angle interruption of 10 ° CA.

-Fire timing control at start-
The starting point fire timing control executed by the ECU 100 will be described.

  First, a problem that occurs when the direct injection engine is started will be described.

  In-cylinder direct-injection engines often start with a lean misfire due to a shortage of the fuel injection period when starting at a low temperature as described above. Specifically, for example, as shown in FIG. 5, when the engine speed ne rapidly increases after the initial explosion, the crank angular acceleration increases in the increasing process (section A). As a result, the fuel injection period is shortened, and the cylinder that was injecting fuel in the section A is misfired without being ignited. As described above, when the in-cylinder direct injection engine is started at a low temperature, the engine is started by repeating [increase in engine speed ne] → [decrease in engine speed ne due to lean misfire].

  In the start with lean misfire as described above, if the ignition advance is performed for the purpose of increasing the torque, the ignition advance may be performed when the engine speed ne is low. There is a possibility that the piston is pushed back by the combustion due to the ignition and the engine rotates in the reverse direction. Therefore, in this embodiment, the ignition timing at the start is controlled so that the torque increase can be achieved while avoiding the reverse rotation of the engine 1 at the low temperature start or the like.

  An example of the specific ignition timing control at the starting time will be described with reference to the flowchart of FIG.

  First, in step ST1, it is determined whether or not the engine 1 is starting (that is, whether or not the engine 1 is being cranked), and if it is starting, the process proceeds to step ST2. When the determination result of step ST1 is negative, this routine is finished.

  In step ST2, a cylinder approaching TDC among the cylinders # 1 to # 6 is determined based on the outputs of the crank position sensor 35 and the cam position sensor 36, and for the determined cylinder, as shown in FIG. The engine speed ne is read from the output of the crank position sensor 35 at the interrupt timing of ° (detection of the engine speed), and it is determined whether or not the engine speed ne at this interrupt timing exceeds 400 rpm (see FIG. 5). ). If the determination result is affirmative, that is, if the engine speed ne is [ne> 400 rpm], the ignition advance is possible (that is, the engine 1 does not reversely rotate even if the ignition advance is performed). ) And the ignition is performed immediately after issuing the ignition instruction at the interrupt timing of BTDC 20 ° (step ST7).

  On the other hand, when the determination result of step ST2 is negative, the process proceeds to step ST3. In step ST3, as shown in FIG. 4, for the cylinder that has passed BTDC 20 °, the engine speed ne is read from the output of the crank position sensor 35 at the interrupt timing of BTDC 10 ° (detection of the engine speed), and this BTDC 10 ° It is determined whether or not the engine speed ne at the interrupt timing exceeds 200 rpm (see FIG. 5) and the cylinder is not ignited at this time. If the determination result is affirmative, that is, if the engine speed ne is [ne> 200 rpm] and [unignited], the ignition advance is possible (that is, the ignition advance is performed). The engine 1 will not reversely rotate), and an ignition instruction is issued at an interrupt timing of BTDC 10 ° and ignition is performed immediately (step ST7).

  On the other hand, if the determination result in step ST3 is negative, it is determined that ignition advance is impossible and the process proceeds to step ST4 to determine whether or not the cylinder is unignited. In step ST5, ignition is performed by normal ignition (for example, hard ignition of BTDC 0 ° or BTDC 5 °).

  Thereafter, when the engine speed ne rises and the engine 1 is in a state where it can operate independently (for example, when the engine speed ne is 600 rpm or more) (when the determination result of step ST6 is negative), This routine ends.

  According to the ignition timing control at the time of cold start, the engine speed ne exceeds 400 rpm at the timing of BTDC 20 ° when each cylinder # 1 to # 6 reaches TDC when the engine 1 is cold started. Or when the engine speed ne exceeds 200 rpm at the timing of BTDC 10 °, it is determined that the ignition advance is possible, and the ignition is immediately performed at each timing BTDC 20 ° or BTDC 10 ° to advance the ignition. Therefore, it is possible to obtain an increase in torque using the increase in the engine speed ne while avoiding the reverse rotation of the engine 1. This makes it possible to start the engine 1 in an optimal state for generating torque for each cylinder according to the engine speed ne.

Furthermore, the determination value (rotation speed) for determining whether or not the ignition advance is possible is set to 400 rpm at BTDC 20 °, and 200 rpm at BTDC 10 °, and different determination values are set according to the degree of advance. Therefore, the increase in the engine speed ne at the start can be used more effectively. That is, even if the engine speed ne is 400 rpm or less at a crank angle of BTDC 20 ° and ignition is not performed, the ignition advance is performed when the engine speed ne exceeds 200 rpm at a crank angle of BTDC 10 °. Therefore, it is possible to increase the torque by more effectively using the increase in the engine speed ne at the start.
-Other embodiments-
In the above example, the determination value of whether or not the ignition advance is possible at the interrupt timing of BTDC 20 ° is 400 rpm, and the determination value of whether or not the ignition advance is possible at the interrupt timing of BTDC 10 ° is 200 rpm. However, each determination value is not particularly limited as long as the engine 1 does not reversely rotate due to the ignition advance angle at each interrupt timing, and is appropriately selected according to the characteristics of the engine to which the present invention is applied. do it.

  In the above example, it is determined whether or not the ignition advance is possible at two interrupt timings of BTDC 20 ° and BTDC 10 °. However, the present invention is not limited to this. For example, BTDC 10 ° Whether or not the ignition advance is possible may be determined at any of a plurality of interrupt timings such as BTDC 15 °, BTDC 20 °, and BTDC 25 °. Further, the possibility of ignition advance may be determined based on one crank angle before compression top dead center (for example, BTDC 20 °).

  In the above example, an example in which the present invention is applied to an in-cylinder direct-injection six-cylinder gasoline engine has been shown. It can also be applied to an in-cylinder direct-injection gasoline engine with the number of cylinders. Further, the present invention is not limited to an in-cylinder direct injection engine, but can be applied to a port injection multi-cylinder gasoline engine.

It is a schematic structure figure showing an example of an engine to which the present invention is applied. It is a block diagram which shows the structure of control systems, such as ECU. It is a flowchart which shows an example of the processing content of the start time fire timing control which ECU performs. FIG. 4 is a diagram showing a crank angle interruption timing before TDC in the starting-time fire timing control of FIG. 3. It is a graph which shows the engine speed at the time of engine starting, and the behavior of crank angular acceleration.

Explanation of symbols

1 Engine 1a Combustion chamber 15 Crankshaft 17 Ring gear 18 Pinion gear 19 Signal rotor 2 Injector (fuel injection valve)
3 Spark plug 4 Igniter 7 Starter motor 31 Water temperature sensor 35 Crank position sensor 37 Ignition switch 100 ECU

Claims (3)

An ignition timing control device for controlling the ignition timing of an internal combustion engine that ignites and burns an air-fuel mixture with an ignition plug,
At the start of the internal combustion engine, the engine speed is detected at a predetermined crank angle before the compression top dead center of each cylinder, and for the cylinders whose engine speed exceeds a predetermined determination value, the compression top dead center An ignition timing control device for an internal combustion engine, comprising ignition timing control means for performing ignition at a predetermined crank angle. In the internal combustion engine ignition timing control device according to claim 1,
The ignition timing control apparatus for an internal combustion engine, wherein the determination value is an engine speed at which the internal combustion engine does not reversely rotate even when ignition is performed at a predetermined crank angle before the compression top dead center. The internal combustion engine ignition timing control device according to claim 1 or 2,
The ignition timing control means detects the engine speed at two different crank angles before compression top dead center, and detects the engine speed at the first crank angle on the advance side of the two crank angles. Ignition is performed when the number exceeds the first determination value, and the engine speed detected at the second crank angle on the compression top dead center side is smaller than the first determination value. An ignition timing control device for an internal combustion engine, wherein ignition is performed when a judgment value is exceeded.

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