JP2015140698A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can complete cylinder discrimination when starting the internal combustion engine.SOLUTION: A control device controls an internal combustion engine having a variable valve timing mechanism which changes opening/closing timing of an intake valve or an exhaust valve by changing a rotational phase difference with respect to a crank shaft of a cam shaft which performs opening/closing drive of the intake valve or the exhaust valve. When the stopped internal combustion engine is restarted, the control device performs cylinder discrimination for discriminating current strokes of respective cylinders by referring to a cam angle signal which is output every time the cam shaft rotates by a prescribed angle. When the opening/closing timing of the valve immediately before a stop of the internal combustion engine or at the stop is displaced from prescribed reference timing, a difference based on a displacement amount of the opening/closing valve, between the cam angle signal in the case that the opening/closing timing of the valve coincides with the reference timing, and an actually-received cam angle signal is used for the cylinder discrimination.

Description

  The present invention relates to a control device for an internal combustion engine that can determine the stroke of each cylinder at the time of starting in a timely manner.

  In a four-stroke internal combustion engine having a plurality of cylinders, it is necessary to know which stroke each cylinder is currently in and to perform fuel injection control and ignition control. An ECU (Electronic Control Unit) that controls the operation of the internal combustion engine receives a crank angle signal (N signal) and a cam angle signal (G signal) that are generated along with cranking when starting the internal combustion engine, and controls each cylinder. The stroke is discriminated, and then fuel injection (synchronous injection) and ignition in accordance with the stroke for each cylinder are started. Various techniques for accurately performing cylinder discrimination have been disclosed (see, for example, Patent Document 1 below).

  FIG. 13 shows a conventional arrangement of crank angle signals and cam angle signals. A crank angle sensor that outputs a crank angle signal senses the rotation angle of the rotor that rotates integrally with the crankshaft. The rotor is formed with teeth or protrusions at predetermined angles along the rotation direction of the crankshaft. Typically, every time the crankshaft rotates 10 °, teeth or protrusions are placed. The crank angle sensor faces the outer periphery of the rotor, detects that individual teeth or protrusions pass near the sensor, and transmits a pulse signal as a crank angle signal each time.

  However, 36 pulses are not output during one revolution of the crankshaft. The teeth or protrusions of the crankshaft rotor are partially missing, and due to the missing teeth, the crank angle signal pulse train is also partially missing. In the illustrated example, pulses corresponding to the seventeenth, eighteenth, twentieth, twenty-first, thirty-fifth, and thirty-sixth pulses are missing. Based on this defect, it is possible to know the absolute angle of the crankshaft. If the timing of the first pulse after the missing thirty-sixth pulse is 0 ° CA (crank angle), the timing of the nineteenth pulse following the missing eighteenth pulse is 180 ° CA. become.

  The cam angle sensor that outputs the cam angle signal senses the rotation angle of the rotor that rotates integrally with the intake camshaft. The rotor is formed with teeth or protrusions for each angle obtained by dividing one rotation of the camshaft by the number of cylinders. In the case of a three-cylinder engine, teeth or protrusions are arranged each time the camshaft rotates 120 °. The camshaft is rotated by receiving a rotational driving force from the crankshaft via a winding transmission mechanism or the like, and its rotational speed is one half of that of the crankshaft. Therefore, the above teeth or protrusions are arranged every 240 ° CA in terms of the crank angle.

  The cam angle sensor faces the outer periphery of the rotor, detects that individual teeth or protrusions pass in the vicinity of the sensor, and transmits a pulse signal as a cam angle signal each time. In the illustrated example, the cam angle signal suggests a timing when the cylinder is deviated toward the advance side by a certain crank angle from the compression top dead center of each cylinder.

  The conventional cylinder discrimination method is as follows. That is, a control device for an internal combustion engine includes a cam angle signal detection counter unit that counts the number of detected cam angle signals, a crank angle signal detection counter unit that counts the number of detected crank angle signals, and a pulse included in the crank angle signal. And a cylinder discriminating unit that discriminates the stroke of each cylinder with reference to the number detected by the cam angle signal detection counter unit at a timing determined based on the loss of. In FIG. 13, a two-stage upper and lower number sequence is shown below the cam angle signal in each case. The upper row (for example, “0, 9, 9, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0” described in the vicinity of a crank angle of 0 ° CA in “normal case”) An example of counting by the crank angle signal detection counter unit is shown. On the other hand, the lower row (for example, “0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0” described near the crank angle 0 ° CA in the “normal case”) These show an example of the count by the said cam angle signal detection counter part.

  The cam angle signal detection counter unit counts up by “1” in accordance with the number of detected cam angle signals.

  The crank angle signal detection counter unit starts counting the number of detected crank angle signals triggered by the detection of the cam angle signal, and when the detected number of crank angle signals reaches the upper limit, The number of detected corner signal detection counters is reset and the counting of the crank angle signal is completed. The crank angle signal detection counter unit returns the detected number of crank angle signals to the initial value when the cam angle signal is detected while counting the detected number of crank angle signals.

  Specifically, the crank angle signal detection counter unit is a decrement counter, and counts from “9” by “1” according to the number of detected crank angle signals, triggered by detection of the cam angle signal. That is, in the conventional crank angle signal detection counter unit, after detecting the cam angle signal, if the crank angle signal is detected nine times (the number of detected crank angle signals reaches the upper limit “9”, in other words, When the counter value of the angle signal becomes “0”), the detection number (“1” or “2”) of the cam angle signal detection counter unit is reset, and the counting of the crank angle signal is ended. When the detected number of cam angle signals and the detected number of crank angle signals are reset, the crank angle signal is not counted until the next cam angle signal is detected.

  Further, the crank angle signal detection counter unit is configured to return the detected number of crank angle signals to the initial value when a cam angle signal is detected while counting the detected number of crank angle signals. In the illustrated example, the counter value of the crank angle signal detection counter unit is returned to “9”. That is, the count starts from “9” triggered by the detection of the cam angle signal, and the count starts again from “9” when the next cam angle signal is detected.

  Such control is performed, for example, if there is variation in the design of each part, extension of the timing chain, and if the variable valve timing mechanism is provided, the rotational phase of the camshaft is fixed and fixed. This is so that it is possible to cope with a problem such as the above.

The cylinder discriminating unit discriminates the stroke of each cylinder with reference to the number detected by the cam angle signal detection counter unit at a timing determined based on a missing pulse included in the crank angle signal. This timing arrives twice in a half cycle, as shown by the two-dot chain line in FIG.
First pattern: 90 ° CA timing after a single missing pulse (missing 35th and 36th pulses due to missing teeth),
Second pattern: 30 ° CA timing after continuous loss of pulses (17th, 18th, 20th, 20th first pulse loss due to missing teeth),
Cylinder discrimination is performed with.

  First, the first pattern will be explained. After cranking is started, the detection of the number of detected crank angle signals is triggered by the detection of the cam angle signal, and a single missing pulse is detected at the cylinder discrimination timing that comes after that. When the detected number of the cam angle signal detection counter section referred to by the cylinder discrimination section is “0”, it is found that the timing is 150 ° CA before the compression top dead center of the third cylinder ( Hereinafter, this determination is referred to as “A determination”). In this case, the spark ignition is executed at the timing of the compression top dead center of the third cylinder that comes after that, and the expansion stroke in which the fuel injected asynchronously is ignited and burned can be performed.

  On the other hand, even with the same first pattern, after cranking is started, counting of the number of detected crank angle signals is triggered by the detection of the cam angle signal, and there is a single missing pulse at the cylinder discrimination timing that comes after that. If the detected number of the cam angle signal detection counter section that is detected and referred to by the cylinder discrimination section is “1” or “2”, the specific condition is set immediately before the first cylinder reaches the compression top dead center. Is determined to be 30 ° CA before the compression top dead center of the first cylinder (hereinafter, this determination is referred to as “B determination”). Therefore, the spark ignition is executed at the timing of the compression top dead center of the first cylinder that comes after that, and an expansion stroke can be performed in which the fuel injected asynchronously is ignited and burned.

  Next, the second pattern will be described. After the cranking is started, the detection of the number of detected crank angle signals is triggered by the detection of the cam angle signal. If the detected number of the cam angle signal detection counter unit that is detected and referred to by the cylinder discrimination unit is “1”, it is determined that it is the timing when the compression top dead center of the third cylinder is reached (hereinafter referred to as “the cylinder top detection point”). This determination is referred to as “C determination”). At this time, an ignition stroke can be performed in which spark ignition is performed in the third cylinder to ignite and burn the asynchronously injected fuel.

  On the other hand, even with the same second pattern, after cranking is started, counting of the number of detected crank angle signals is triggered by the detection of the cam angle signal. If the detected number of the cam angle signal detection counter unit that is detected and referred to by the cylinder discrimination unit is “0”, it is determined that the timing is 120 ° CA before the compression top dead center of the second cylinder. (Hereinafter, this determination is referred to as “D determination”). Therefore, the spark ignition is executed at the timing of the compression top dead center of the second cylinder that comes after that, and an expansion stroke can be performed in which the fuel injected asynchronously is ignited and burned.

  By the way, as a variable valve timing mechanism incidental to an internal combustion engine, various electric variable valve timing mechanisms using a motor as a drive source are known (for example, see Patent Document 2 below). The electric variable valve timing mechanism, for example, controls the valve timing of the intake valve to change the phase greatly toward the retarded angle, thereby closing the intake valve on the retarded side from the intake bottom dead center of the piston. This is effective for controlling the Atkinson cycle (Miller cycle). In the Atkinson cycle, the closing timing of the intake valve is delayed from the intake bottom dead center of the piston, so that the intake air sucked into the cylinder is blown back toward the intake passage at the beginning of the compression stroke. Therefore, the substantial start of the compression stroke is delayed, and as a result, a high expansion ratio can be obtained without increasing the actual compression ratio. As the expansion ratio is increased, the substantial piston stroke in the expansion stroke can be increased. Therefore, the thermal energy of the fuel can be efficiently converted into kinetic energy, and the thermal efficiency of the engine can be improved. In addition, since a substantial intake air amount is reduced, a significant reduction in fuel consumption can be realized.

JP-A-5-10227 JP 2008-2299 A

  The internal combustion engine attached with the above-described electric variable valve timing mechanism has a camshaft crankshaft at the start of the internal combustion engine as compared with an internal combustion engine attached with a so-called hydraulic variable valve timing mechanism using hydraulic pressure as a drive source. The rotation phase for is not fixed. In addition, the electric variable valve timing mechanism has a larger movable range of the camshaft rotation phase with respect to the crankshaft than the hydraulic variable valve timing mechanism. That is, the phase can be greatly changed from the reference position when the phase is not changed by the variable valve timing mechanism not only to the advance side but also to the retard side. Therefore, the electric type may be detected at a timing when the cam angle signal is largely deviated from the normal position to the retard side as compared with the hydraulic type.

Here, in FIG. 13, the following three cases, namely,
・ Ideal "normal case",
・ "Advance case" greatly deviated toward the advance angle side (for example, when deviating toward the 60 [deg.] CA advance angle side from the normal case),
・ "Delayed case" greatly deviated to the retarded side (for example, deviated to the 50 ° CA retarded side from the normal case)
Is shown.

  Comparing these cases, even the conventional control method can cope with the shift of the cam angle signal to the advance side. That is, even if the detection of the cam angle signal is different from the “normal case”, in many cases, the same detection number of the cam angle signal detection counter unit as that of the “normal case” can be obtained.

  However, in some of the “delay cases”, the same detection number of the cam angle signal detection counter unit as in the “normal case” cannot be obtained, and the cylinder discrimination may be wrong.

  Specifically, at the timing when the crank angle is 90 ° CA, in the first pattern, the number of detections of the cam angle signal detection counter unit is “0”, and the A determination should be made. In the “case”, the detected number of the cam angle signal detection counter unit is “1”, and the B determination is made. For this reason, it is erroneously determined that the first cylinder is immediately before reaching the compression top dead center, and combustion is not appropriately performed in the third cylinder, so that a cylinder determination process is required again.

  Further, at the timing when the crank angle is 240 ° CA, the number of detections of the cam angle signal detection counter unit is “1” in the second pattern and the C determination should be made. The number detected by the cam angle signal detection counter unit is “0”, and the D determination is made. Therefore, it is erroneously determined that the timing of 120 ° CA is reached before the second cylinder reaches the compression top dead center, and combustion in the third cylinder is not properly performed, so that another cylinder determination process is required. .

  Further, at the timing when the crank angle is 600 ° CA, in the second pattern, the number of detections of the cam angle signal detection counter unit is “0” and the D determination should be made. The number of detections of the cam angle signal detection counter is “1” or “2”, and the C determination is made. Therefore, it is erroneously determined that the third cylinder is at the compression top dead center, and combustion is not properly performed in the second cylinder, so that a second cylinder determination process is required.

  If the cylinder is discriminated in this way, ignition cannot be performed in accordance with the compression top dead center timing of the cylinder that is first visited when the internal combustion engine is restarted, and the time spent for cranking accordingly. Will be extended.

  The present invention, for the first time, focused on the problem that cylinder discrimination may not be completed when starting an internal combustion engine equipped with a variable valve timing mechanism, particularly due to a large shift to the retard side, It is an intended object of the present invention to provide a control device for an internal combustion engine that can complete cylinder discrimination when starting the internal combustion engine.

  The control apparatus for an internal combustion engine of the present invention includes an internal combustion engine provided with a variable valve timing mechanism that changes the opening / closing timing of the valve by changing the rotational phase difference of the camshaft for opening / closing the intake valve or the exhaust valve with respect to the crankshaft. When the stopped internal combustion engine is restarted, cylinder discrimination is performed in which the current stroke of each cylinder is discriminated by referring to a cam angle signal output every time the camshaft rotates by a predetermined angle. When the opening / closing timing of the valve immediately before or at the time of stopping the internal combustion engine is displaced from a predetermined reference timing, the opening / closing timing of the valve matches the reference timing based on the amount of displacement of the opening / closing timing. The difference between the cam angle signal and the actually received cam angle signal when There wherein the used.

  According to the present invention, the cylinder discrimination can be completed when the internal combustion engine is started.

The figure which shows the whole structure of the internal combustion engine for vehicles in 1st Embodiment of this invention. The figure which shows the variable valve timing mechanism which the control apparatus of the embodiment controls. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. BB sectional drawing of FIG. The figure which shows typically the aspect of the crank angle sensor accompanying the internal combustion engine of the embodiment. The figure which shows typically the aspect of the cam angle sensor accompanying the internal combustion engine of the embodiment. The figure which shows the hardware resource structure of the embodiment. The timing diagram explaining the content of the cylinder discrimination | determination performed in the internal combustion engine of the embodiment. The timing diagram which expands and shows a part of FIG. The timing diagram which expands and shows a part of FIG. The timing diagram which expands and shows a part of FIG. The timing diagram explaining the content of the cylinder discrimination | determination performed in the internal combustion engine of the modification of this invention. The timing diagram explaining the content of the cylinder discrimination | determination performed in the conventional internal combustion engine.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type four-stroke engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  In the internal combustion engine in the present embodiment, an intake valve and an exhaust valve are provided at the top of the cylinder, the intake valve is driven by the intake camshaft 7, and the exhaust valve is driven by the exhaust camshaft. The intake camshaft 7 and the exhaust camshaft are connected by a chain, a gear, or the like, and rotate at the same rotational speed.

  The phase of the intake valve is controlled by an intake variable valve timing mechanism 6 provided on the intake camshaft 7. The variable valve timing mechanism 6 changes the opening / closing timing of the intake valve by changing the rotational phase difference of the camshaft 7 that drives the intake valve to open / close, and is controlled by the ECU 0. 66. That is, as an example, the variable valve timing mechanism 6 shown in FIG. 2 includes a sprocket 61, a cam plate 62, a link mechanism 63, a guide plate 64, a speed reducer 65, and an electric motor 66.

  The sprocket 61 is connected to the crankshaft via a chain or the like. The number of revolutions of the sprocket 61 is one half of the number of revolutions of the crankshaft. The intake camshaft 7 is provided so as to be rotatable relative to the sprocket 61 on a concentric axis with the rotation axis of the sprocket 61.

  The cam plate 62 is connected to the intake camshaft 7 by a pin 67. The cam plate 62 rotates integrally with the intake camshaft 7 inside the sprocket 61.

  The link mechanism 63 includes arms 631 and 632. As shown in FIG. 3, a pair of arms 631 are provided in the sprocket 61 so as to be point-symmetric with respect to the rotation axis of the intake camshaft 7. Each arm 631 is connected to the sprocket 61 so as to be swingable about the pin 68. As shown in FIG. 3, the arm 631 and the cam plate 62 are connected by an arm 632. The arm 632 is supported so as to be swingable with respect to the arm 631 around the pin 69. The arm 632 is supported so as to be swingable with respect to the cam plate 62 around the pin 60.

  Then, the intake camshaft 7 rotates relative to the sprocket 61 by the pair of link mechanisms 63, and the phase of the intake valve is changed. A control pin 633 is provided on the surface of each link mechanism 63 on the guide plate 64 side. The control pin 633 is provided on a concentric shaft with the pin 69. Each control pin 633 slides in a guide groove 641 provided in the guide plate 64.

  Each control pin 633 is moved in the radial direction by sliding in the guide groove 641 of the guide plate 64. By moving each control pin 633 in the radial direction, the intake camshaft 7 is rotated relative to the sprocket 61.

  As shown in FIG. 4, the guide groove 641 is formed in a spiral shape so that each control pin 633 is moved in the radial direction by the rotation of the guide plate 64. As the control pin 633 moves away from the axis of the guide plate 64 in the radial direction, the phase of the intake valve is retarded more. That is, the amount of change in phase becomes a value corresponding to the amount of operation of the link mechanism 63 due to the control pin 633 changing in the radial direction.

  As shown in FIG. 4, when the control pin 633 contacts the end of the guide groove 641, the operation of the link mechanism 63 is limited. Therefore, the phase at which the control pin 633 contacts the end of the guide groove 641 is the most retarded angle or most advanced angle phase.

  In FIG. 2, the guide plate 64 is provided with a plurality of recesses 642 for connecting the guide plate 64 and the speed reducer 65 on the surface on the speed reducer 65 side.

  The reduction gear 65 includes an external gear 651 and an internal gear 652. The external gear 651 is fixed to the sprocket 61 so as to rotate integrally with the sprocket 61. The internal gear 651 is formed with a plurality of convex portions 653 that are received in the concave portions 642 of the guide plate 64. The internal gear 651 is supported so as to be rotatable about an eccentric shaft of a coupling 661 formed eccentrically with respect to the shaft center 662 of the output shaft of the electric motor 66.

  The internal gear 652 is provided such that some of the plurality of teeth mesh with the external gear 651. When the output shaft rotational speed of the electric motor 66 is the same as the rotational speed of the sprocket 61, the coupling 661 and the internal gear 652 rotate at the same rotational speed as the external gear 651 (and the sprocket 61). In this case, the guide plate 64 rotates at the same rotational speed as the sprocket 61, and the phase of the intake valve is maintained.

  When the coupling 661 is rotated relative to the external gear 651 about the shaft center 662 by the electric motor 66, the entire internal gear 652 rotates (revolves) about the shaft center 662, The internal gear 652 rotates around the eccentric shaft 663. Due to the rotational movement of the internal gear 652, the guide plate 64 is rotated relative to the sprocket 61, and the phase of the intake valve is changed. The phase of the intake valve changes when the relative rotational speed between the output shaft of the electric motor 66 and the sprocket 61 (that is, the operation amount of the electric motor 66) is reduced by the speed reducer 65, the guide plate 64, and the link mechanism 63. To do.

  The overall reduction ratio of the variable valve timing mechanism 6 (in other words, the ratio of the relative rotational speed between the output shaft of the electric motor 66 and the sprocket 61 with respect to the phase change amount) can take a value corresponding to the phase of the intake valve. In this embodiment, the larger the reduction ratio, the smaller the amount of phase change with respect to the relative rotational speed between the output shaft of the electric motor 66 and the sprocket 61.

  When the phase of the intake valve (intake camshaft 7) is advanced, the electric motor 66 is operated to rotate the guide plate 64 relative to the sprocket 61. On the other hand, when the phase is retarded, the output shaft of the electric motor 66 is rotated relative to the sprocket 61 in the direction opposite to that when the phase is advanced. As a result, as long as the relative rotation direction of the output shaft of the electric motor 66 and the sprocket 61 is the same, the phase of the intake valve is advanced or retarded between the most retarded angle and the most advanced angle. Can be.

  Further, since the reduction ratio is large in the most retarded region, a large torque is required to rotate the output shaft of the electric motor 66 by the torque acting on the intake camshaft 7 as the internal combustion engine is operated. Become. Therefore, even when the electric motor 66 does not generate torque, such as when the electric motor 66 is stopped, it is possible to prevent the output shaft of the electric motor 66 from being rotated by the torque acting on the intake camshaft 7. Therefore, it can suppress that an actual phase changes from the phase on control.

  That is, the variable valve timing mechanism 6 of the present embodiment is configured so that the phase can be maintained by overcoming the cam torque while the electric motor 66 is stopped, and the force acting from the intake valve side can be ignored. It can be considered that the phase angle of the intake valve does not change. Therefore, the phase angle of the intake valve immediately before the stop of the internal combustion engine can be regarded as the phase angle of the intake valve when the internal combustion engine is restarted.

  The control signal m output from the ECU 0 to the motor 66 is, for example, via a drive circuit in which a speed feedback function for converting a rotation speed instruction into driving of the motor 66 is incorporated. That is, by directly instructing the advance angle / retard angle speed from the ECU 0, in other words, only the motor speed command is sent from the ECU 0 to the drive circuit, and feedback control of the motor speed with respect to the command value of the ECU 0 is performed in the drive circuit. I am doing so.

  The ECU 0 as the control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal (N signal) b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, An accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as an accelerator opening (so-called required load), and a brake that is output from a sensor that detects the amount of depression of the brake pedal Stepping amount signal d, intake air temperature / intake pressure signal e output from a temperature / pressure sensor for detecting intake air temperature and intake pressure in intake passage 3 (especially surge tank 33), water temperature sensor for detecting engine cooling water temperature From the cam angle sensor at a plurality of cam angles of the cooling water temperature signal f output from the intake camshaft 7 or the exhaust camshaft. A cam angle signal (G signal) g is the force, a sensor for to know the range of the shift lever (or, a shift position switch) shift range signal h or the like to be output from is input. The accelerator opening is a so-called required load. The coolant temperature of the internal combustion engine indicates the temperature of the internal combustion engine.

  From the output interface, an ignition signal i for the igniter 13 of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, a control signal m for the electric motor 66, etc. Is output.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. As the operation parameter determination method itself, a known method can be adopted. The ECU 0 applies various control signals i, j, k, m corresponding to the operation parameters via the output interface.

  In addition, the ECU 0 inputs a control signal s to the electric motor (starter motor or motor generator) when the internal combustion engine is started (a cold start or a return from an idling stop). Cranking is performed by rotating the crankshaft. Cranking ends when the internal combustion engine reaches from the first explosion to the continuous explosion and the engine speed, that is, the rotation speed of the crankshaft, exceeds a judgment value determined according to the coolant temperature, etc. (assuming that the explosion has been completed) To do.

  Here, the crank angle signal b and the cam angle signal g will be supplemented. As shown in FIG. 5, the crank angle sensor senses the rotation angle of the rotor 8 that is fixed to the crankshaft and rotates integrally with the crankshaft. The rotor 8 is formed with teeth or protrusions 81 at every predetermined angle along the rotation direction of the crankshaft. Typically, every time the crankshaft rotates 10 °, teeth or protrusions 81 are arranged.

  The crank angle sensor faces the outer periphery of the rotor 8, detects that each tooth or protrusion 81 passes near the sensor, and transmits a pulse signal as a crank angle signal b each time. The ECU 0 receives this pulse as the crank angle signal b.

  However, the crank angle sensor does not output 36 pulses during one rotation of the crankshaft. The teeth or protrusions 81 of the crankshaft rotor 8 are partially missing. In the example shown in FIG. 5, the seventeenth, eighteenth, twentyth, and twentyth first missing tooth portions 82 and the thirty fifth and thirty sixth missing tooth portions 83 are roughly divided into two. There are two missing tooth portions 82, 83. The missing tooth portions 82 and 83 each correspond to a specific rotational phase angle of the crankshaft. That is, the continuous missing tooth portion 82 corresponds to 180 ° CA and 540 ° CA, and the single missing tooth portion 83 corresponds to 0 ° CA and 360 ° CA.

  Then, as shown in FIG. 8, due to the above-mentioned missing tooth portions 82 and 83, part of the pulse train of the crank angle signal b is also lost. Based on this defect, it is possible to know the absolute angle of the crankshaft. If the timing of the first pulse after the missing thirty-sixth pulse is 0 ° CA (or 360 ° CA), the timing of the nineteenth pulse following the missing eighteenth pulse is 180 °. That is, CA (or 540 ° CA). The timing of the 0 ° CA pulse is substantially equal to the compression top dead center of a specific cylinder (second cylinder in the illustrated example) 1.

  As shown in FIG. 6, the cam angle sensor also senses the rotation angle of the rotor 9 that is fixed to the camshaft 7 and rotates integrally with the camshaft 7. The rotor 9 is formed with teeth or protrusions 91 at every angle obtained by dividing at least one rotation of the camshaft 7 by the number of cylinders. In the case of a three-cylinder engine, each time the camshaft 7 rotates 120 °, a tooth or protrusion 91 is arranged.

  The camshaft 7 is rotated by receiving a rotational driving force from the crankshaft via a winding transmission mechanism (chain and sprocket, not shown) and the like, and its rotational speed is one half that of the crankshaft. . Therefore, the above-described teeth or protrusions 91 are arranged every 240 ° CA in terms of the crank angle.

  In addition, in the present embodiment, the rotor 9 is provided with one tooth or protrusion 92 for generating an additional cam angle signal g between the teeth or protrusions 91 every 240 ° CA.

  The cam angle sensor faces the outer periphery of the rotor 9, detects that each tooth or protrusion 91, 92 passes near the sensor, and transmits a pulse signal as the cam angle signal g each time. The ECU 0 receives this pulse as the cam angle signal g.

  The basic cam angle signal g generated due to the teeth or protrusions 91 indicates that any cylinder 1 has reached a predetermined stroke. When the intake camshaft 7 is accompanied by a cam angle sensor, the basic cam angle signal g output from the cam angle sensor is, as shown in FIG. 8, near the compression top dead center in each cylinder 1, or This suggests a timing when the piston deviates from the compression top dead center by a predetermined crank angle (a value within the range of 30 ° CA to 70 ° CA) toward the advance side. In an internal combustion engine with a so-called phase change type variable valve timing mechanism 6, the cam angle signal g also represents the valve timing adjusted by the mechanism.

  The additional cam angle signal g generated due to the teeth or protrusions 92 corresponds to a specific rotational phase angle of the camshaft 7 (and the crankshaft), and assists in determining the stroke of each cylinder 1. It will be. In the example shown in FIG. 6, the pulse of the additional cam angle signal g exists at the timing advanced by 60 ° CA from the pulse of the basic cam angle signal g representing the vicinity of the compression top dead center of the first cylinder 1. Yes. When these two cam angle signal g pulses are continuously received at an interval of 60 ° CA, which is apparent from the pulse train of the crank angle signal b, the compression top dead center of the first cylinder 1 is immediately after the latter pulse. It turns out that it is.

  That is, in the internal combustion engine of the present embodiment, the crank angle sensor attached to the crankshaft outputs the crank angle signal b every time the crankshaft rotates by a unit angle, and the crankshaft is rotated at a specific rotational phase angle of the crankshaft. The angle signal b is lost without being output, and the cam angle sensor associated with the camshaft 7 that rotates following the crankshaft and drives the intake valve to open and close is fundamental each time the camshaft 7 rotates by a unit angle. In addition to outputting the cam angle signal g, an additional cam angle signal g is output at a specific rotational phase angle of the camshaft 7. The cam angle sensor may detect a rotation of a rotor fixed to an exhaust cam shaft that rotationally drives the exhaust valve and output a basic cam angle signal and an additional cam angle signal.

  The ECU 0 of the present embodiment performs cranking for rotationally driving the crankshaft by the starter motor when starting the stopped internal combustion engine, and substantially simultaneously with the start of the cranking (immediately before the start of the cranking, At the same time or immediately after starting), asynchronous injection is performed in which fuel is injected into all three cylinders 1 all at once.

  Then, the crank angle signal b and the cam angle signal g generated with the rotation of the crankshaft are received, and the stroke of each cylinder 1 is determined. When the determination of the stroke of each cylinder 1 is completed, synchronous injection and spark ignition for injecting fuel individually for each cylinder 1 are started. During cranking of the internal combustion engine, for each cylinder 1, synchronous injection is performed at a timing immediately before the exhaust top dead center, and spark ignition is performed at a timing immediately after the compression top dead center.

  Hereinafter, the cylinder discrimination method at the start in the present embodiment will be described.

  In this embodiment, when restarting the stopped internal combustion engine, the ECU 0 refers to the cam angle signal g output every time the camshaft 7 rotates by a predetermined angle, and determines the current stroke of each cylinder 1. When the valve opening / closing timing immediately before or during the stop of the internal combustion engine is displaced from a predetermined reference timing, the valve opening / closing timing based on the amount of displacement of the opening / closing timing is a reference. The difference between the cam angle signal g and the actually received cam angle signal g when the timing is met is used in the cylinder discrimination. Here, the reference timing is, for example, a timing when the phase is changed by the variable valve timing mechanism 6.

  Specifically, the ECU 0 of the present embodiment includes a cam angle signal detection counter unit 21 that counts the number of detected cam angle signals g, a crank angle signal detection counter unit 22 that counts the detected number of crank angle signals b, A cylinder discriminating unit 23 that discriminates the stroke of each cylinder 1 with reference to the number detected by the cam angle signal detection counter unit 21 at a timing determined based on a missing pulse included in the crank angle signal b, and corresponds to the reference timing. A count for detecting the phase difference between the position and the position corresponding to the current actual opening / closing timing, and changing the upper limit value of the number of detected crank angle signals b counted by the crank angle signal detection counter unit 22 based on the phase difference. A period adjustment unit 24.

  8 to 11, the upper and lower two-stage number sequences are shown below the cam angle signal g in each case. The upper row (for example, “0, 9, 9, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0” described in the vicinity of a crank angle of 0 ° CA in “normal case”) An example of counting by the crank angle signal detection counter unit 22 is shown. On the other hand, the lower row (for example, “0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0” described near the crank angle 0 ° CA in the “normal case”) These show an example of the count by the cam angle signal detection counter unit 21.

  The cam angle signal detection counter unit 21 operates the hardware resources in accordance with the program, and performs a count that increases by “1” according to the number of detected cam angle signals g.

  The crank angle signal detection counter unit 22 operates the hardware resources in accordance with the program, starts counting the number of detected crank angle signals b triggered by the detection of the cam angle signal g, and calculates the crank angle signal b being counted. When the detected number reaches the upper limit, the number detected by the cam angle signal detection counter unit 21 is reset and the counting of the crank angle signal b is ended. When the cam angle signal g is detected while the number of detected crank angle signals b is being counted, the crank angle signal detection counter unit 22 decrements the number of detected crank angle signals b by a predetermined number.

  Specifically, the crank angle signal detection counter unit 22 is a decrement counter, and performs a count that is decremented by “1” from “9” according to the number of detected crank angle signals b, triggered by detection of the cam angle signal g. . That is, in the crank angle signal detection counter unit 22 of the present embodiment, when the crank angle signal b is detected nine times after the cam angle signal g is detected (the number of detected crank angle signals b reaches “9” which is the upper limit value). In other words, when the counter value of the crank angle signal b becomes “0”), the detected number (“1” or “2”) of the cam angle signal detection counter unit 21 is reset, and the crank angle signal b End counting. When the number of detected cam angle signals g and the number of detected crank angle signals b are reset, the crank angle signal b is not counted until the next cam angle signal g is detected.

  Furthermore, when the cam angle signal g is detected while counting the number of detected crank angle signals b, the crank angle signal detection counter unit 22 of the present embodiment sets the number of detected crank angle signals b to a predetermined number. (Specifically, “2”). In the illustrated example, the counter value of the crank angle signal detection counter unit 22 is increased by “2”. Therefore, the count starts from “9” triggered by the detection of the cam angle signal g, and is returned by “2” counts by the detection of the next cam angle signal g.

  The crank angle signal detection counter unit is not limited to the decrement counter described above. For example, a count that increases by “1” from “1” according to the number of detected crank angle signals is triggered by the detection of the cam angle signal. A total counter to be performed may be used. Further, the crank angle signal detection counter section may be configured to return the detected number of crank angle signals to the initial value when the cam angle signal is detected while counting the detected number of crank angle signals. Good.

And the cylinder discrimination | determination part 23 of this embodiment refers to the detection number of the cam angle signal detection counter part 21 at the timing defined based on the missing | missing of the pulse contained in the crank angle signal b, and discriminate | determines the stroke of each cylinder 1. To do. As shown by the two-dot chain line in FIG. 8, this timing comes twice in a half cycle, specifically,
First pattern: 90 ° CA timing after a single missing pulse (missing 35th and 36th pulses due to missing tooth 83),
Second pattern: 30 ° CA timing after continuous loss of pulses (missing of the 17th, 18th, 20th, and 20th pulses due to the missing tooth portion 82),
Cylinder discrimination is performed with.

  In order to detect a missing pulse of the crank angle signal b, it is necessary to further receive a pulse train for 30 ° CA, which is equal to the interval between the pulse immediately before and after the missing pulse. Therefore, the loss of the 35th and 36th pulses is detected and the cylinder discrimination is completed after the third pulse of the crank angle signal b is received. Also, it is after receiving the 24th pulse of the crank angle signal b that the missing of the 17th, 18th, 20th, and 20th first pulses is detected and the cylinder discrimination is completed. .

  First, the first pattern will be described. As shown in FIG. 9, after the cranking is started, the detection of the number of detected crank angle signals b is started with the detection of the cam angle signal g, and the cylinder discrimination which comes after that is started. When a single missing pulse is detected at the timing and the number of detections of the cam angle signal detection counter unit 21 referred to by the cylinder discrimination unit 23 is “0”, before the compression top dead center of the third cylinder 1 It turns out that the timing is 150 ° CA. Then, the spark ignition is executed at the timing of the compression top dead center of the third cylinder 1 that comes after that (the timing becomes clear by the crank angle signal b), and the fuel injected asynchronously is ignited and burned. Can run the expansion stroke.

  On the other hand, even in the same first pattern, as shown in FIG. 11, after the cranking is started, the detection of the number of detected crank angle signals b is started when the cam angle signal g is detected. When a single missing pulse is detected at the determination timing and the number of detections of the cam angle signal detection counter unit 21 referred to by the cylinder determination unit 23 is “1” or “2”, the first cylinder 1 It is found that the timing is 30 ° CA immediately before reaching the compression top dead center, specifically, before the compression top dead center of the first cylinder 1. Therefore, the spark stroke is executed at the timing of the compression top dead center of the first cylinder 1 that comes after that (the timing is made clear by the crank angle signal b), and the expansion stroke in which the fuel injected asynchronously is ignited and burned. Can be run. Since the additional cam angle signal g is generated prior to the basic cam angle signal g representing the timing immediately before the first cylinder 1 reaches the compression top dead center, the cylinder discrimination is made in time for the ignition timing, and the compression top dead center. The first cylinder 1 can be ignited at a point.

  Next, the second pattern will be described. As shown in FIG. 10, after cranking is started, counting of the detected number of crank angle signals b is started with the detection of the cam angle signal g, and the cylinders that come thereafter When the continuous missing of the pulse is detected at the discrimination timing and the number of detections of the cam angle signal detection counter unit 21 referred to by the cylinder discrimination unit 23 is “1”, the compression top dead center of the third cylinder 1 It turns out that it is the timing which reached. At this time, spark ignition is executed in the third cylinder 1, and an expansion stroke can be performed in which the fuel injected asynchronously is ignited and burned. The basic cam angle signal g indicating the timing of compression top dead center of the third cylinder 1 is detected before the 24th crank angle signal b, and the 24th crank angle signal b is Since the timing is near the compression top dead center of the cylinder 1, the cylinder discrimination is in time for the ignition timing, and the third cylinder 1 can be ignited at the compression top dead center.

  On the other hand, even in the same second pattern, as shown in FIG. 11, after the cranking is started, the detection of the number of detected crank angle signals b is started with the detection of the cam angle signal g, and the cylinder that reaches after that is started. When the continuous missing of the pulse is detected at the determination timing and the detected number of the cam angle signal detection counter unit 21 referred to by the cylinder determination unit 23 is “0”, the compression top dead center of the second cylinder 1 It turns out that the timing is 120 ° CA. Therefore, the spark stroke is performed at the timing of the compression top dead center of the second cylinder 1 that comes after that (the timing is made clear by the crank angle signal b), and the expansion stroke in which the fuel injected asynchronously is ignited and burned. Can be run.

  The count period adjusting unit 24 operates the hardware resource according to the program, and when the opening / closing timing of the intake valve immediately before the stop of the internal combustion engine is displaced from the predetermined reference timing to the retard side, the opening / closing timing displacement The difference between the cam angle signal g and the actually received cam angle signal g when the intake valve opening / closing timing matches the reference timing based on the amount is used in the cylinder discrimination. That is, in the present embodiment, when performing cylinder discrimination, the opening / closing timing of the intake valve by the variable valve timing mechanism 6 is taken into account.

  Specifically, first, the ECU 0 acquires the phase of the intake camshaft 7 (and the intake valve) when the cam angle signal g is detected by the cam angle sensor. Specifically, the phase angle of the intake valve immediately before the stop of the internal combustion engine corresponding to the signal m commanded by the ECU 0 to the electric motor 66 immediately before the stop of the internal combustion engine is set to the phase angle of the intake valve at the current start of the internal combustion engine. It is considered. The phase of the intake camshaft 7 at this time is expressed with reference to the crank angle.

  Thereafter, the ECU 0 compares the acquired phase of the intake camshaft 7, that is, the current position of the cam angle signal g (immediately before the stop) and the reference position when the phase is not changed by the variable valve timing mechanism 6. Detect the phase difference. Here, the reference position in the present embodiment is any of 210 ° CA, 390 ° CA and 690 ° CA corresponding to the basic cam angle signal g, and 450 ° CA corresponding to the additional cam angle signal g. . Among these reference positions, the position closest to the current position is adopted as the reference position for comparison. Specifically, when the current position of the cam angle signal g is 150 ° CA, the phase difference is 60 ° CA compared to the reference position of 210 ° CA, which is shifted to the advance side. Judgment is made. Further, when the current position of the cam angle signal g is 250 ° CA, it is determined that the phase difference is 50 ° CA compared to the reference position of 210 ° CA and is shifted to the retard side. To do.

  Next, when the ECU 0 is displaced from the reference position to the retard angle side, the ECU 0 changes the upper limit value of the number of detected crank angle signals b counted by the crank angle signal detection counter unit 22 according to the amount of displacement. That is, when the phase difference occurs on the retarded angle side, the cylinder discrimination effective period, in other words, the detection of the crank angle signal b by the crank angle signal detection counter unit 22 is compared with the case where the phase difference does not occur. Shorten the period from the start of counting to the end. Specifically, when the phase difference occurs on the retard side, the initial value when the crank angle signal detection counter unit 22 starts counting is changed, and the amount corresponding to the phase difference from the reference position is changed. Only the count of the number of detected crank angle signals b in the crank angle signal detection counter unit 22 is advanced. When the opening / closing timing of the intake valve matches the reference timing, the count is reduced by “1” from “9” according to the number of detected crank angle signals “b” triggered by the detection of the cam angle signal “g”. Start counting from the value of.

  More specifically, as shown in FIG. 8, when the current position is 260 ° CA and a phase difference of 50 ° CA occurs between the reference position and 210 ° CA on the retard side. In response to the detection of the crank angle signal b (signal at 210 ° CA) corresponding to the cam angle signal g at the reference position, the count was reduced by “1” from “9” according to the number of detected crank angle signals b. In this case, the count starts from “4” triggered by the detection of the actual cam angle signal g. In addition, when the current position is 740 ° CA (20 ° CA) and a phase difference of 50 ° CA occurs between the reference position and 690 ° CA on the retard side, the cam angle of the reference position is The value when the count is decreased from “9” by “1” according to the number of detected crank angle signals b triggered by detection of the crank angle signal b (signal at 690 ° CA) corresponding to the signal g, that is, Counting starts from “6” triggered by the actual detection of the cam angle signal g.

  In the present embodiment, when the phase difference occurs on the advance side, the above-described control is not performed, and the stroke of each cylinder 1 is discriminated using the cam angle signal g actually received as before. To do.

  By the way, in this embodiment having the electric variable valve timing mechanism 6 as in the present embodiment, the phase angle of the camshaft 7 at the start of the internal combustion engine is indefinite, and the cam angle signal g is advanced from the reference position. Alternatively, it may be detected at a timing greatly deviating toward the retard side.

For example, in FIGS. 8 to 11, the following three cases, that is,
・ Ideal "normal case",
-"Leading case" shifted to the advance side (for example, shifted to 60 ° CA advance side from the normal case),
・ "Delayed case" shifted to the retarded angle side (for example, shifted to 50 ° CA retarded side from the normal case)
Is shown.

  Comparing these cases, according to the ECU 0 as the control device of the present embodiment, not only the cam angle signal g shifts to the advance side but also the delay side shift can be reliably handled. It has become. That is, even in the “delay case” that has been a problem in the past, the same number of detections by the cam angle signal detection counter unit 21 as in the “normal case” can be obtained. Therefore, in any of the illustrated “advanced case” and “delayed case”, the same accurate cylinder discrimination as in the “normal case” can be performed, and combustion is appropriately performed in the cylinder 1 to be ignited next. Will be done.

  Thus, according to the present embodiment, it is possible to accurately determine the stroke of each cylinder 1 when starting the internal combustion engine regardless of the presence or absence of a factor that affects the detection timing of the cam angle signal g. Ignition and combustion can be performed reliably. As a result, it contributes to shortening of the cranking period and can improve fuel consumption.

  The present invention is not limited to the embodiment described in detail above.

  For example, the present invention may be applied to a shift toward the advance side. Specifically, as shown in FIG. 12, the control device according to the modification of the present invention compares the acquired camshaft phase with the reference position when the cam angle signal is detected by the cam angle sensor. The phase difference is detected, and when the opening / closing timing of the valve immediately before or when the internal combustion engine is stopped is displaced from the predetermined reference timing to the advance side, the cylinder is discriminated based on the displacement amount of the opening / closing timing. I do. Specifically, when the phase difference occurs on the advance side, the cylinder discrimination effective period is lengthened as compared with the case where no phase difference occurs. In other words, when the phase difference occurs on the advance side, the crank angle signal detection counter unit does not reduce the count regardless of the number of detected crank angle signals until the phase difference from the reference position disappears. Then, with the detection of the crank angle signal corresponding to the cam angle signal at the reference position as a trigger, the count is reduced by “1” from “9” according to the number of detected crank angle signals.

  In such a case, even in the case of the “advance case” shifted to the advance side shown in FIG. 12 (for example, the case shifted to 60 ° CA advance side from the normal case), the cam It is possible to reliably handle the deviation of the angle signal toward the advance side, and accurately determine the stroke of each cylinder when starting the internal combustion engine regardless of the presence or absence of factors that affect the detection timing of the cam angle signal. It becomes.

  Although the internal combustion engine in the above embodiment is of the port injection type, the present invention can also be applied to start control of a direct injection internal combustion engine that injects fuel directly into the combustion chamber of each cylinder. is there.

  Further, the specific mode of the variable valve timing mechanism is arbitrary and is not limited to a unique one. The intake camshaft and / or exhaust camshaft rotation phase relative to the crankshaft is advanced / retarded by hydraulic pressure, the intake valve and / or exhaust valve is an electromagnetic solenoid valve, or the intake valve is opened. There are known a plurality of intake cams that drive valves and / or exhaust cams that open and drive exhaust valves and use them appropriately, and those that change the lever ratio of the rocker arm with an electric motor. It is allowed to select and employ from various mechanisms. When a variable valve timing mechanism that changes the opening / closing timing of the exhaust valve is adopted, the cam angle sensor that transmits the cam angle signal of the present invention outputs the cam angle signal every time the exhaust camshaft rotates by a predetermined angle. Apply what you want to output.

  Further, in the above-described embodiment, the valve opening / closing timing immediately before the stop of the internal combustion engine is regarded as the valve opening / closing timing at the time of restart. However, the present invention is not limited to this, for example, when the internal combustion engine is stopped. The valve opening / closing timing may be regarded as the valve opening / closing timing at the time of restart.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be used for starting control of an internal combustion engine mounted on a vehicle.

0 ... Control unit (ECU)
1 ... Cylinder 6 ... Variable valve timing mechanism 7 ... Camshaft

Claims (1)

A control device for controlling an internal combustion engine attached with a variable valve timing mechanism for changing the opening / closing timing of the valve by changing a rotational phase difference of a camshaft for opening / closing driving of an intake valve or an exhaust valve with respect to a crankshaft,
When restarting the stopped internal combustion engine, a cylinder discrimination is performed in which a current stroke of each cylinder is discriminated by referring to a cam angle signal output every time the camshaft rotates by a predetermined angle.
When the opening / closing timing of the valve immediately before or when the internal combustion engine is stopped is displaced from a predetermined reference timing,
A control apparatus for an internal combustion engine, which uses a difference between a cam angle signal and an actually received cam angle signal when the valve opening / closing timing matches a reference timing based on a displacement amount of the opening / closing timing in the cylinder discrimination .

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