JP2014105696A - Control unit for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control unit for an internal combustion engine, which can generate a simulated crank angle signal more accurately reflecting a change in crank angle under an abnormal condition of a crank angle sensor.SOLUTION: An ECU 0 serving as a control unit for an internal combustion engine generates a plurality of simulated crank angle signals having unequal intervals with respect to time intervals among successively-output cam angle signals g, on the basis of a control parameter, under an abnormal condition of a crank angler sensor, and performs combustion control on the basis of the simulated crank angle signals and the cam angle signals g.

Description

  The present invention relates to a control device for an internal combustion engine including a crank angle sensor and a cam angle sensor.

  2. Description of the Related Art Conventionally, a crank angle sensor that outputs an engine crank angle signal, a cam angle sensor that outputs an engine cam angle signal, and a control device for an internal combustion engine that determines a cylinder of the internal combustion engine from the crank angle sensor and the cam angle sensor. Various proposals have been made. Among them, the one described in Patent Document 1 is based on a control parameter based on a simulated crank angle signal that is equally spaced with respect to a time interval between the cam angle signals that are continuously output when the crank angle sensor is abnormal. And combustion control is performed based on the simulated crank angle signal and the cam angle signal (see, for example, Patent Document 1). As a result, emergency avoidance action can be performed even when the output of the crank angle sensor breaks down.

  However, the above-mentioned patent document generates a pseudo timing of the crank angle signal by equally dividing the time interval of the output timing of the cam angle signal into a plurality of times. For this reason, a deviation from the actual movement (rotational fluctuation) of the crank angle signal occurs. Therefore, if the ignition timing is excessively advanced due to the deviation, it causes knocking. That is, when performing control as in the above-described known technique, it is necessary to provide a large safety margin in the control of the ignition timing and the fuel injection amount in order to prevent knocking as described above. Specifically, it is necessary to greatly retard the ignition timing. If this happens, conversely, if the ignition timing is too retarded due to the deviation, it may occur that the torque becomes insufficient or the exhaust becomes too hot and damages the catalyst. In particular, the above-mentioned problem that the ignition timing is too retarded leads to a shortage of torque, particularly for an internal combustion engine with a small displacement or a small number of cylinders, which hinders the emergency evacuation behavior itself when the crank angle sensor fails. It will also lead to the situation that comes.

JP 2011-208509 A

  The present invention focuses on such problems and provides a control device for an internal combustion engine that can generate a simulated crank angle signal that more accurately reflects the movement of the crank angle when the crank angle sensor is abnormal. It is aimed.

  In order to achieve such an object, the present invention takes the following measures.

  That is, a control device for an internal combustion engine according to the present invention includes a crank angle sensor that outputs a crank angle signal of an engine, a cam angle sensor that outputs a cam angle signal of the engine, and the crank angle sensor and the cam angle sensor. A control device for an internal combustion engine that performs cylinder discrimination, and controls a plurality of simulated crank angle signals that are unequal to a time interval between cam angle signals that are continuously output when the crank angle sensor is abnormal. It is generated based on parameters, and combustion control is performed based on the simulated crank angle signal and the cam angle signal.

  With such a configuration, even when the crank angle sensor breaks down or the like, control can be performed at a timing close to the actual crank angle. Therefore, it is possible to suppress a so-called safety margin of the combustion control performed when the crank angle sensor has failed, such as delaying the ignition timing. As a result, it is possible to suppress a decrease in torque caused by providing the safety margin, and therefore, even in an internal combustion engine having a small number of cylinders or a small displacement, reliable emergency avoidance action with guaranteed output is performed. Can do.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can produce | generate the simulation crank angle signal which reflected the movement of the crank angle more correctly at the time of abnormality of a crank angle sensor can be provided.

The figure which shows the whole structure of the internal combustion engine for vehicles in one Embodiment of this invention. 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 timing diagram explaining the content of the cylinder discrimination | determination process performed in the internal combustion engine of the embodiment. Action | operation explanatory drawing which concerns on the same embodiment.

  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 of the present embodiment is a port injection type four-stroke spark ignition engine having a displacement of 660 cc, for example, and includes three cylinders 1 (one of which is shown in FIG. 1). These cylinders 1 are arranged in series, and the compression top dead center of each cylinder 1 appears at regular intervals, that is, every 240 ° CA.

  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.

  The ECU 0 serving as a control device for the internal combustion engine 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, and a battery that is output from a sensor that detects the voltage (or battery current) of a vehicle-mounted battery A voltage signal d, an intake air temperature / intake air pressure signal e output from a temperature / pressure sensor for detecting intake air temperature and intake air pressure in the intake passage 3 (particularly, the surge tank 33), an internal combustion engine coolant (or coolant) ) Of the coolant temperature signal f output from the fluid temperature sensor for detecting the temperature of the intake camshaft or the exhaust camshaft. The cam angle signal (G signal) g output from the cam angle sensor and the shift range signal h output from the sensor (or shift position switch) for obtaining the shift lever range are 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 is output to the igniter of the spark plug 12, a fuel injection signal j is output to the injector 11, an opening operation signal k is output to the throttle valve 32, and the like.

  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 fuel injections 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 corresponding to the operation parameters via the output interface.

  In addition, the ECU 0 sends a control signal o to a starter motor (or a cell motor, not shown) that is an electric motor when the internal combustion engine is started (a cold start or a return from an idling stop). The cranking is performed by rotating the crankshaft of the internal combustion engine by the starter motor. Cranking ends from the first explosion to the consecutive explosion, and ends when the engine speed exceeds a threshold determined according to the coolant temperature or the like (assuming that the explosion has been completed).

  Here, the crank angle signal b and the cam angle signal g will be supplemented. As shown in FIG. 2, the crank angle sensor senses the rotation angle of the rotor 7 that is fixed to the crankshaft and rotates integrally with the crankshaft. The rotor 7 is formed with teeth or protrusions 71 at predetermined angles along the rotation direction of the crankshaft. Typically, every time the crankshaft rotates 10 °, a tooth or projection 71 is placed.

  The crank angle sensor faces the outer periphery of the rotor 7, detects that each tooth or protrusion 71 passes in the vicinity of the sensor, and transmits a pulse signal as the 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 71 of the crankshaft rotor 7 are partially missing. In the example shown in FIG. 2, the seventeenth, eighteenth, twentyth, and twentyth first missing tooth portions 72 and the thirty-fifth and thirty-sixth missing tooth portions 73 are roughly divided into two. There are two missing tooth portions 72,73. The missing tooth portions 72 and 73 each correspond to a specific rotational phase angle of the crankshaft. That is, the continuous missing tooth portion 72 corresponds to 180 ° CA and 540 ° CA, and the single missing tooth portion 73 corresponds to 0 ° and 360 ° CA.

  As shown in FIG. 4, due to the above-mentioned missing tooth portions 72 and 73, a 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. 3, the cam angle sensor also senses the rotation angle of the rotor 8 that is fixed to the cam shaft and rotates integrally with the cam shaft. The rotor 8 is formed with teeth or protrusions 81 at every angle obtained by dividing at least one rotation of the camshaft by the number of cylinders. In the case of a three-cylinder engine, each time the camshaft rotates 120 °, teeth or protrusions 81 are arranged.

  The camshaft 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 half that of the crankshaft. Therefore, the above-described teeth or protrusions 81 are arranged every 240 ° CA in terms of the crank angle.

  The cam 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 the cam angle signal g each time. The ECU 0 receives this pulse as the cam angle signal g.

  The cam angle signal g generated due to the teeth or protrusions 81 indicates that any cylinder 1 has reached a predetermined stroke. When the cam angle sensor is attached to the intake camshaft, the cam angle signal g output from the cam angle sensor is, as shown in FIG. This indicates a timing when the crankshaft is deviated toward the advance side by a predetermined crank angle (a value within a range of 30 ° CA to 70 ° CA) from the dead center. In an internal combustion engine with a so-called phase change type variable valve timing mechanism, the cam angle signal g also represents a valve timing adjusted by the mechanism.

  The ECU 0 obtains the current stroke of each cylinder 1 by referring to both the crank angle signal b and the cam angle signal g, performs synchronous injection in which fuel is injected at an appropriate fuel injection timing in each cylinder 1, In addition, the air-fuel mixture is ignited at an appropriate ignition timing.

  Therefore, the ECU 0 as the control device for the internal combustion engine according to the present embodiment includes a plurality of simulated cranks that are unequal to the time interval between the cam angle signals g that are continuously output when the crank angle sensor is abnormal. An angle signal (simulated N signal) is generated based on the control parameter, and combustion control is performed based on the simulated crank angle signal and the cam angle signal g.

  The upper part of FIG. 4 shows the time required for the crankshaft to rotate 30 ° CA in each stroke of the internal combustion engine. As shown in the figure, the rotational speed of the crankshaft tends to increase the time required for the crankshaft to rotate when any cylinder 1 is near the compression top dead center, that is, the rotational speed tends to decrease. This actually appears as crankshaft pulsation. The difference in the required time related to the pulsation, that is, the rotational speed difference A shown in the figure varies depending on various control parameters such as engine speed, required load, ignition timing, coolant temperature, and load by auxiliary equipment.

  In this embodiment, the ECU 0 stores in advance signal patterns of a plurality of simulated crank angle signals b that are unequal with respect to the time interval between the cam angle signals g, for example, as a plurality of maps. This signal pattern can be appropriately selected according to the value of the rotational speed difference A of the crankshaft predicted by various control parameters. As shown in FIG. 5, the signal pattern of the simulated crank angle signal includes a wide interval region α in the vicinity of which one of the cylinders 1 is at the compression top dead center, and a narrow interval region interposed between the wide interval regions α. β. In the wide interval region α, the simulated crank angle signal is set such that the time required for rotating by 30 ° CA is longer than the time obtained by dividing the time interval between the cam angle signals g into eight equal parts. In the narrow interval region β, the simulated crank angle signal is set so that the time required for rotating by 30 ° CA is shorter than the time obtained by dividing the time interval between the cam angle signals g into eight equal parts. . The signal patterns stored in the ECU 0 have different time intervals between the wide interval region α and the narrow interval region β. That is, when the pulsation of rotation of the crankshaft is large, a signal pattern having a large time difference between the wide space region α and the narrow space region β is read from the ECU 0.

  Hereinafter, combustion control when the crank angle sensor according to the present embodiment is abnormal will be described with reference to FIGS.

  Hereinafter, the control when the crank angle sensor is abnormal in the present embodiment will be specifically described. First, when an abnormality occurs in the crank angle sensor due to disconnection or the like, the value of the rotational speed difference A that causes pulsation in FIG. 4 is predicted from the control parameter, and stored in the ECU 0 from the value of the rotational speed difference A. An arbitrary signal pattern is read out from the plurality of signal patterns. The timing at which the next cam angle signal g is transmitted is predicted from the timing of the cam angle signal g transmitted so far, and the time difference between the latest cam angle signal g and the predicted cam angle signal g and the signal pattern are estimated. Is used to generate a simulated crank angle signal, and combustion control is performed based on the simulated crank angle signal. Here, according to the abnormality of the crank angle sensor, a so-called safety margin may be provided in the control of the ignition timing and the fuel injection amount, that is, the combustion control as in the conventional case. In other words, correction that has been conventionally performed to correct the ignition timing to the retard angle side and reduce the fuel injection amount in accordance with the abnormality of the crank angle sensor may be performed. Furthermore, the amount of correction in the safety margin is made different in association with the plurality of signal patterns, or the safety margin is not provided depending on the read signal pattern, for example, the signal pattern when the value of the rotational speed difference A is small. You may do it.

  As described above, as shown in FIG. 5, the ECU 0, which is the control device for the internal combustion engine according to the present embodiment, outputs continuously when the crank angle sensor is abnormal to respond to the pulsation of the crankshaft. A plurality of simulated crank angle signals having unequal intervals with respect to the time interval between the cam angle signals g generated are generated based on control parameters, and combustion control is performed based on the simulated crank angle signals and the cam angle signal g. Therefore, a crank angle value closer to the timing at which the actual crank angle signal b is output can be obtained, and combustion control can be performed accurately. In particular, in the present embodiment, since the signal pattern of the simulated crank angle signal has a wide interval region α in the vicinity of the compression top dead center, the timing near the compression top dead center is later than the time obtained by simply dividing the cam angle signal g equally. A simulated crank angle signal is generated. As a result, it is effectively avoided that the ignition timing is too advanced compared to the case where the ignition timing is set based on the time obtained by equally dividing the cam angle signal g. As a result, combustion control in which knocking is avoided is realized without providing a so-called safety margin for correcting the ignition timing to the retard side.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, the mode of the simulated crank angle signal is determined based on the engine speed and the required load. Of course, in addition to the control parameters described above, other control parameters such as the EGR amount, the EGR rate, and the CVT state are also taken into consideration. Also good. In addition, aspects such as a pulse train for generating an actual crank angle signal and a specific timing at which the cam angle signal is output are not limited to those of the above-described embodiment, and various aspects including the existing ones may be used. Can be applied.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  The present invention can be used for controlling an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 1 ... Cylinder b ... Crank angle signal g ... Cam angle signal 0 ... Internal combustion engine control apparatus (ECU)

Claims (1)

A crank angle sensor for outputting an engine crank angle signal;
A cam angle sensor for outputting an engine cam angle signal;
A control device for an internal combustion engine that performs cylinder discrimination of the internal combustion engine from the crank angle sensor and the cam angle sensor,
When an abnormality occurs in the crank angle sensor, a plurality of simulated crank angle signals that are unequal to the time interval between the cam angle signals that are continuously output are generated based on the control parameter, and the simulated crank angle signal A control device for an internal combustion engine that performs combustion control based on the cam angle signal.

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