JP2015048728A - 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 effectively avoid a stall during operation.SOLUTION: A control device of an internal combustion engine, when determining that a fuel injection and ignition timing concerning a cylinder are erroneous, stops the fuel injection and ignition and then starts cylinder discrimination again. In the cylinder discrimination performed during normal operation other than starting, when the rotation speed of a crankshaft is equal to or lower than a predetermined value or the gradient of a lowering rate in the rotation angle velocity of the crankshaft is equal to or larger than a predetermined gradient, the control device of an internal combustion engine determines that the cylinder discrimination is performed correctly and executes a fuel injection and ignition.

Description

  The present invention relates to a control device for an internal combustion engine that can determine the stroke of each cylinder 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.

  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, for example, 10 °, teeth or protrusions are arranged. 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, for example, 36 pulses are not output at equal angular intervals during one revolution of the crankshaft. The teeth or protrusions of the rotor of the crankshaft are partially missing, often in the amount of one or two, and due to the missing tooth part, the pulse train of the crank angle signal is also partially lost.

  Various techniques for accurately detecting the reference position of the crankshaft by recognizing the position of the missing tooth and performing accurate cylinder discrimination have been disclosed (for example, see Patent Document 1).

  Here, if the above-described cylinder determination is erroneously determined at the time of start-up, combustion is not properly performed and a cylinder determination process is required again. As a result, the crank angle signal (N signal) and the cam angle signal (G signal) are received with the fuel injection and ignition stopped once, and the cylinder discrimination process is performed again. That is, in such a case, the time spent for cranking is extended by the cylinder discrimination process to be performed again and the time before fuel injection and ignition are stopped.

  In many cases, the loss of the pulse signal caused by the missing tooth portion is repeated once, i.e., when the loss occurs once, i.e., once independently, and the loss of the pulse signal is repeated twice, with a pulse interposed. The teeth or protrusions are formed on the rotor so that the occurrence of Therefore, recently, a technique is also disclosed in which the crank angle signal is appropriately shaped to accurately grasp the pulse signal regardless of the number of consecutive missing teeth and accurately detect the reference position of the crankshaft. (For example, refer to Patent Document 2).

  By the way, the above-described cylinder discrimination based on the missing tooth portions of the rotor having different continuous times is performed not only at the start but also at the normal operation other than the start. That is, in order to confirm whether or not fuel injection and injection at that time are properly performed even during operation, cylinder discrimination is performed at intervals of twice / 720 ° CA per missing tooth portion.

  However, even during operation, when the rotational speed is low or the angular velocity is greatly reduced, the interval between the pulse signals may fluctuate greatly due to fluctuations in the rotational speed.

  Here, if the loss of the pulse signal suddenly arrives only once and then the angular speed of the crankshaft suddenly drops, it will be judged that the loss is twice, leading to an erroneous determination of cylinder discrimination. May end up. In such a case, the cylinder discrimination is reset once, that is, the fuel injection and the ignition are stopped, and then the fuel injection (synchronous injection) and the ignition corresponding to the stroke of each cylinder are started as in the above-mentioned start. It becomes. However, the fact that such fuel injection and ignition are stopped during normal operation means that the possibility of the internal combustion engine stalling is significantly increased by further reducing the rotational speed of the internal combustion engine at this time. There are concerns about such problems.

JP-A-6-307280 JP 2005-105882 A

  The present invention focuses on the above-described problems, and an object thereof is to provide a control device for an internal combustion engine that can effectively avoid stall during operation.

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

  That is, in the control device for an internal combustion engine according to the present invention, the crank angle sensor attached to the crankshaft outputs a crank angle signal as a pulse signal every time the crankshaft rotates by a unit angle, and a specific rotational phase angle of the crankshaft. The pulse signal is lost without being output, and the missing pulse signal is a single missing tooth defect that occurs once independently during rotation of the crankshaft and the missing pulse signal is the pulse signal. The stroke of each cylinder is discriminated based on a plurality of missing teeth missing continuously several times through the cylinder, and when it is discriminated that the fuel injection and ignition timing for the cylinder are incorrect, the fuel injection and ignition Is a control device for an internal combustion engine that stops cylinder discrimination and then starts cylinder discrimination again, during normal operation other than at startup If the crankshaft rotation speed is less than a predetermined value or the gradient of the decrease in the rotational speed of the crankshaft is greater than or equal to a predetermined gradient in the cylinder determination performed, the cylinder determination is performed based on the missing single missing tooth. It is characterized by prohibition.

  If this is the case, a single missing tooth cannot be recognized as a single missing tooth due to an extreme disturbance in the pulse signal due to the rotational speed or the degree of decrease in the rotational speed. It is possible to effectively prevent a stall due to a further decrease in the rotational speed due to the stop of fuel injection and ignition due to an erroneous determination that the current cylinder position is abnormal. it can. As a result, stall during operation can be effectively avoided.

  In addition, in order to more effectively avoid erroneous cylinder discrimination during normal operation and further reduce the possibility of incurring a stall, there is a requirement that the predetermined value of the rotation speed is induced to cause fluctuations in the rotation speed. It is desirable to set higher as the operating condition is established.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can avoid the stall during driving | operation effectively 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 the variable valve timing mechanism which the control apparatus which concerns on the same embodiment controls. The figure which shows typically the aspect of the crank angle sensor accompanying the internal combustion engine which concerns on the same embodiment. The figure which shows typically the aspect of the cam angle sensor accompanying the internal combustion engine which concerns on the same embodiment. The figure which shows the hardware resource structure which concerns on the same embodiment. The timing diagram explaining the contents of cylinder discrimination concerning the embodiment. The figure for demonstrating typically the effect | action which concerns on the same embodiment. Same as above. The timing diagram which shows the control which concerns on embodiment. The flowchart 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 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.

  As shown in FIG. 2, in the internal combustion engine in the present embodiment, a timing chain 74 is wound around a crank sprocket 71, an intake side sprocket 72 and an exhaust side sprocket 73, and the rotational driving force provided from the crankshaft by this timing chain 74. Is transmitted to the intake camshaft via the intake side sprocket 72 and to the exhaust camshaft via the exhaust side sprocket 73.

  In addition, a variable valve timing mechanism 6 is interposed between the intake side sprocket 72 and the intake camshaft. The variable valve timing mechanism 6 in the present embodiment changes the opening / closing timing of the intake valve by changing the rotational phase of the intake camshaft with respect to the crankshaft.

  The housing 61 of the variable valve timing mechanism 6 is fixed to the intake side sprocket 72, and the intake side sprocket 72 and the housing 61 are integrally rotated in synchronization with the crankshaft. On the other hand, the rotor 62 fixed to one end portion of the intake camshaft is housed in the housing 61 and can rotate relative to the intake-side sprocket 72 and the housing 61. A plurality of fluid chambers into which hydraulic fluid flows in and out are formed inside the housing 61, and each fluid chamber is partitioned into an advance chamber 612 and a retard chamber 611 by a vane 621 formed on the outer peripheral portion of the rotor 62. Has been.

  The hydraulic fluid stored in the oil pan 81 is supplied from the hydraulic pump 82 to the hydraulic pressure (particularly hydraulic) circuit of the variable valve timing mechanism 6. The hydraulic pump 82 is driven by power from the internal combustion engine. An OCV (Oil Control Valve) 9 that is a switching control valve is provided between the hydraulic pump 82 and the variable valve timing mechanism 6. By operating the flow rate and direction of the hydraulic fluid via the OCV 9, the hydraulic fluid pumped from the oil pan 81 can be selectively supplied to the advance chamber 612 or the retard chamber 611. Then, the housing 61 rotates relative to the rotor 62, and the opening / closing timing of the intake valve can be advanced or retarded.

  The OCV 9 is a so-called electromagnetic four-way spool valve. As shown in FIG. 2, the OCV 9 has a supply port 91 connected to the discharge port of the hydraulic pump 82, an A port 92 connected to the advance chamber 612 of the housing 61, and a B port connected to the retard chamber 611 of the housing 61. 93 and drain ports 94 and 95 connected to the oil pan 81. The spool of the OCV 9 switches the internal particle path by an advancing and retreating operation, and connects the A port 92 and the B port 93 to one of the supply port 91 and the drain ports 94 and 95, respectively. Further, when the spool 96 is in the neutral position, the internal fluid path is interrupted, and the A port 92 and the B port 93 are not communicated with the supply port 91 and the drain ports 94 and 95. FIG. 2 shows a state where the spool 96 is in the neutral position.

  The spool 96 is driven by a solenoid 97. That is, the advance / retreat distance of the spool 96 changes according to the duty ratio of the pulse current (or voltage) input to the solenoid 97 as the control signal m. When the duty ratio of the control signal m is relatively large, the hydraulic fluid pressure discharged from the hydraulic pump 82 is supplied to the advance chamber 612 through the A port 92, while already stored in the retard chamber 611. The hydraulic fluid flows down toward the oil pan 81 through the B port 93, and the vane 621 and the rotor 62 are rotated so that the volume of the advance chamber 612 is enlarged and the volume of the retard chamber 611 is reduced. As a result, the rotational phase of the intake camshaft, in other words, the displacement angle of the intake camshaft with respect to the crankshaft is advanced, and the valve timing of the intake valve is advanced.

  On the contrary, when the duty ratio of the control signal m is relatively small, the hydraulic fluid pressure discharged from the hydraulic pump 82 is supplied to the retard chamber 611 through the B port 93, while already stored in the advance chamber 612. The working fluid that has flown down flows toward the oil pan 81 through the A port 92, and the vane 621 and the rotor 62 rotate so that the volume of the retard chamber 611 is expanded and the volume of the advance chamber 612 is decreased. . As a result, the displacement angle of the intake camshaft with respect to the crankshaft is retarded, and the valve timing of the intake valve is retarded.

  Generally speaking, the valve timing of the intake valve is advanced faster as the duty ratio of the control signal m is larger than neutral, and the valve timing of the intake valve is retarded faster as the duty ratio is smaller than neutral.

  An ECU (Electronic Control Unit) 0 that is a 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 Output from the cam angle sensor at a plurality of cam angles of the cooling water temperature signal f output from the intake camshaft or exhaust camshaft. Cam angle signal (G signal) g, shift range signal h output from a sensor (or shift position switch) for knowing the range of the shift lever, lighting, air conditioner, heater, defogger, audio equipment A signal o or the like is input from an operation input device (operation switch, button, touch panel, etc.) operated by a user's hand who desires to operate a car navigation system or the like. The accelerator opening is a so-called required load. The cooling water 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 13 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, a control signal m is output to the OCV 9, and the like. To do.

  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, h, o necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and fills the cylinder 1 Estimate the amount of intake air. 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 outputs various control signals i, j, k, m corresponding to the operation parameters, control signals for operating auxiliary equipment such as an illumination lamp, an air conditioner, a heater, an audio device, and a car navigation system. . The control signal includes a clutch connection signal n1 for switching connection / disconnection of an electromagnetic clutch (not shown) that mediates transmission of rotational driving force from the crankshaft of the internal combustion engine to the compressor for refrigerant compression, and an illustration for cooling the radiator. In addition to the fan drive signal n2 that drives the fan motor that does not, a signal for turning on / off the power to each of the illumination lamp, fan motor, heater, defogger, audio device, car navigation system, and the like is included.

  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. 3, the crank angle sensor senses the rotation angle of the rotor 75 that is fixed to the crankshaft and rotates integrally with the crankshaft. The rotor 75 is formed with teeth or projections 76 at every predetermined angle along the rotation direction of the crankshaft. Typically, each time the crankshaft rotates 10 °, a tooth or projection 76 is placed.

  The crank angle sensor faces the outer periphery of the rotor 75, detects that each tooth or protrusion 76 passes near 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 76 of the crankshaft rotor 75 are partially missing. In the example shown in FIG. 3, the seventeenth, eighteenth, twentieth, twenty first tooth missing portions 761 and the thirty fifth and thirty sixth missing tooth portions 762 are roughly divided into two. There are two missing tooth portions 761, 762. The missing tooth portions 761 and 762 each correspond to a specific rotational phase angle of the crankshaft. That is, the continuous missing tooth portion 761 corresponds to 180 ° CA and 540 ° CA, and the single missing tooth portion 762 corresponds to 0 ° and 360 ° CA.

  Then, as shown in FIG. 6, part of the pulse train of the crank angle signal b is also lost due to the above-mentioned missing tooth portions 761 and 762 that come alternately by rotation of the crankshaft. 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. 4, the cam angle sensor also senses the rotation angle of a rotor 77 that is fixed to the cam shaft and rotates integrally with the cam shaft. The rotor 77 is formed with teeth or protrusions 78 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, teeth or protrusions 78 are arranged every time the camshaft rotates 120 °.

  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 78 are arranged every 240 ° CA in terms of the crank angle.

  In addition, in the present embodiment, the rotor 77 is provided with one tooth or protrusion 79 for generating an additional cam angle signal g between the teeth or protrusions 78 every 240 ° CA.

  The cam angle sensor faces the outer periphery of the rotor 77, detects that individual teeth or protrusions 78 and 79 pass in the vicinity of 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 78 indicates that any cylinder 1 has reached a predetermined stroke. When the cam angle sensor is attached to the intake camshaft, the basic cam angle signal g output from the cam angle sensor is near the compression top dead center in each cylinder 1 as shown in FIG. This indicates a timing when the crankshaft is deviated from the top dead center by a predetermined crank angle (a value within a range of 30 ° CA to 70 ° CA). 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 additional cam angle signal g generated due to the teeth or protrusions 79 corresponds to a specific rotational phase angle of the camshaft (and crankshaft), and assists in determining the stroke of each cylinder 1. Is. In the example shown in FIG. 4, 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 basic cam angle is generated each time the camshaft sensor attached to the camshaft that rotates following the crankshaft and opens and closes the intake valve rotates a unit angle. In addition to outputting the signal g, an additional cam angle signal g is output at a specific rotational phase angle of the camshaft.

  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 the present embodiment, the ECU 0 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 number of detected crank angle signals b, and a crank angle signal b. And a cylinder discriminating unit 23 for discriminating 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 the missing pulse included in the. In FIG. 6, the upper and lower two-stage number sequences are shown below the cam angle signal g in each case. The upper stage (for example, “0, 7, 7, 7, 6, 5, 4, 3, 2, 1, 0” described near a crank angle of 0 ° CA in the “normal case”) is the crank angle signal. An example of counting by the detection counter unit 22 is shown. On the other hand, the lower stage (for example, “0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0” described near a crank angle of 0 ° CA in the “normal case”) An example of counting by the angular signal detection counter unit 21 is shown.

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

  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 “7” 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 seven times after the cam angle signal g is detected (the number of detected crank angle signals b reaches “7” 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, “3”). In the illustrated example, the counter value of the crank angle signal detection counter unit 22 is increased by “3”. Therefore, the count starts from “7” triggered by the detection of the cam angle signal g, and is returned by “3” counts by the detection of the next cam angle signal g.

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. 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 tooth portion 762),
Second pattern: 30 ° CA timing after continuous loss of pulses (17th, 18th, 20th, 20th first pulse loss due to missing tooth part 761),
Cylinder discrimination is performed with.

  Here, in order to detect a missing pulse of the crank angle signal b, it is necessary to further receive a pulse train of 30 ° CA equal to the interval between the pulse immediately before the missing pulse and the pulse immediately after the missing pulse. Therefore, it is confirmed that the loss of the 35th and 36th pulses is detected and the loss of the pulse is a single missing pulse of the first pattern which is a single missing tooth, that is, the first pattern missing tooth. The check is completed after the third pulse of the crank angle signal b is received. In addition, it is confirmed that the loss of the 17th, 18th, 20th, and 20th first pulse is detected, and the loss of the pulse is a continuous loss of the pulse according to the second pattern in which a plurality of missing teeth are missing, That is, the second pattern missing tooth check is completed after receiving the 24th pulse of the crank angle signal b. The first pattern missing tooth check described here will be described in detail later.

By the way, in such an internal combustion engine, for example, if there is a variation in design of each part, an extension of the timing chain 74, and a variable valve timing mechanism 6 as in this embodiment, the rotational phase of the camshaft. There is a possibility that problems such as being fixed with a constant value may occur. In such a case, the cam angle signal g is detected at a timing shifted from the normal side to the advance side or from the retard side. For example, in FIG. 6, there are four cases:
・ Ideal "normal case",
・ "Case of advance" deviated to the advance side (specifically, described in the upper section <Fixed + design variation (10 ° CA) with the variable valve timing mechanism in the most advanced state (45 ° CA)) Yes> and <the variable valve timing mechanism fixed at the most advanced state (45 ° CA) + design variation (10 ° CA) + control delay (20 ° CA)>)
"Delay case" shifted to the retarded angle side (specifically, the state where the timing chain is extended (10 ° CA) + design variation (10 ° CA))
・ "Deteriorated delay case" greatly shifted to the retarded side (specifically, the state where the timing chain is extended (10 ° CA) + design variation (10 ° CA) + control delay (20 ° CA))
Is shown.

  Comparing these cases, according to the ECU 0 as the control device of the present embodiment, it is possible to reliably cope with the shift of the cam angle signal g to the advance side or the delay side. That is, in the other cases different from the “normal case”, particularly the “deteriorated delay case” that has been a problem in the past, the same number of detections of the cam angle signal detection counter unit 21 as the “normal case” can be obtained. Can do. Therefore, in any of the first pattern and the second pattern, any of the illustrated “advanced case”, “delayed case”, and “deteriorated delayed case” is “normal case”. The same accurate cylinder discrimination can be performed, and combustion is appropriately performed in the cylinder 1 to be ignited next.

  First, the first pattern will be described. As shown in FIG. 6, 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 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, after cranking is started, counting of the number of detected crank angle signals b is triggered by the detection of the cam angle signal g. When the missing portion is detected 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 reaches the compression top dead center. It turns out immediately before, specifically, the timing of 30 ° CA 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. After the cranking is started, the detection of the cam angle signal g is started, and the detection of the number of crank angle signals b is started. When the missing portion is detected and the number of detections of the cam angle signal detection counter unit 21 referred to by the cylinder determination unit 23 is “1”, it is the timing when the compression top dead center of the third cylinder 1 is reached. Becomes clear. 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, after the cranking is started, the detection of the number of detected crank angle signals b is triggered by the detection of the cam angle signal g. When a defect is detected and the number of detections of the cam angle signal detection counter unit 21 referred to by the cylinder determination unit 23 is “0”, the timing is 120 ° CA before the compression top dead center of the second cylinder 1. It turns out that there is. 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.

  On the other hand, if the cylinder is misidentified at the start due to factors other than the above, ignition cannot be performed in accordance with the timing of the compression top dead center of the cylinder 1 that comes first when the internal combustion engine is restarted. The time spent for cranking will be extended by that amount.

  Further, the ECU as the control device for the internal combustion engine according to the present embodiment makes an error in the timing of fuel injection and ignition during operation by performing the above-described cylinder discrimination not only at the start but also at the normal operation after the start. It can be avoided.

  Here, as shown in FIG. 7, in the normal operation and at a normal time when the rotation speed is a certain level or more, and the fluctuation of the rotation speed is stable even if the rotation speed is low, the first pattern missing as described above. Cylinder discrimination by tooth check is carried out smoothly. That is, as shown in the figure, the crankshaft rotates stably when a single missing tooth missing pulse (missing thirty-fifth and thirty-sixth pulses caused by the missing tooth portion 762) is detected. The time interval α between the crank angle signal b caused by the thirty-fourth tooth or projection 76 (# 34) and the crank angle signal b caused by the first tooth or projection 76 (# 1). Is detected as a time interval approximately equal to or close to three times the time interval β of the crank angle signal b between the first and second teeth or protrusions 76 (# 1) and 76 (# 2). This is because that. Even if the cylinder is misidentified for some reason, the fuel injection and ignition are stopped while the rotation of the crankshaft is stably maintained, and the asynchronous injection and ignition related to the next cylinder discrimination are performed. Is executed promptly and the operation is promptly returned to the operation at the correct fuel injection and ignition timing.

  However, as shown in FIG. 8, if the crankshaft rotational speed is low or the gradient of the degree of decrease in the rotational angular speed of the crankshaft is large in the discrimination of the cylinder 1 performed during normal operation other than at the start, the rotational speed Since fluctuations also increase, there is a possibility of misclassification. That is, as shown in the figure, the crank is detected when a single missing tooth missing pulse (missing 35th and 36th pulses due to missing tooth portion 762) is detected during the first pattern missing tooth check. When the rotation of the shaft is unstable and the rotational speed temporarily decreases, the crank angle signal b caused by the thirty-fourth tooth or protrusion 76 (# 34) and the first tooth or protrusion The time interval α of the crank angle signal b resulting from 76 (# 1) is the time interval β of the crank angle signal b between the first and second teeth or protrusions 76 (# 1) and 76 (# 2). Is detected as a time interval longer than that in the normal time, and therefore is detected as a time interval comparable to the time interval α. Then, the ECU 0 determines these time intervals α and β as missing pulses. Thereby, the single missing pulse of the missing tooth portion 762 is mistakenly identified as the continuous missing that is the missing missing tooth of the pulse related to the missing tooth portion 761. As a result, fuel injection and ignition are stopped to perform cylinder discrimination again. In this case, since the fuel injection and ignition are stopped when the rotational speed is low as described above, the internal combustion engine is exposed to a situation where the engine stalls.

  Therefore, in the ECU 0 according to the present embodiment, the crankshaft rotation speed is less than or equal to a predetermined value x or the gradient of the decrease in the rotational angular velocity of the crankshaft is greater than or equal to a predetermined gradient in the discrimination of the cylinder 1 that is performed during normal operation other than startup. In such a case, the cylinder discrimination including the first pattern missing tooth check itself based on the single missing pulse (missing 35th and 36th pulses due to the missing tooth portion 762) is not performed. In addition, fuel injection and injection are performed.

  That is, as shown in FIG. 9, when the rotational speed decreases, it is detected that the rotational speed is lower than a predetermined value (x, x1), or the rotational fluctuation value, that is, the gradient of the decrease in the rotational speed is a predetermined gradient. If it is greater than θ, the first pattern missing tooth check mask, in other words, the first pattern missing tooth check itself is not performed. In the figure, a mode in which the first pattern missing tooth check mask is performed when the rotational speed is lower than a predetermined value x is shown. Then, although the rotational speed temporarily fluctuates, the fuel injection and ignition are continued, and thus the rotational speed increases from the predetermined value x. If the rotational speed x exceeds a predetermined value, the first pattern missing tooth check mask is released. Further, when the first pattern missing tooth check is performed as in the past, the erroneous injection as shown in FIG. 8 is caused to stop the fuel injection and ignition, and the internal combustion period is stalled. In FIG. 9, the state of such a rotational speed is shown by an imaginary line.

  Further, in the present embodiment, in the same figure, in the case where the driving condition establishes a fluctuation inducing factor, the internal combustion engine may stall by performing the same control as described above by setting the predetermined value to x1 larger than x. Is more effectively eliminated. Specifically, the fluctuation inducing factor is that the brake pedal or the accelerator pedal is depressed during the first pattern missing tooth check, the misfire of the internal combustion engine occurs, or the input side rotation speed on the automatic transmissions 8 and 9 side. Exceeds the rotation speed of the crankshaft, causes the drag of the internal combustion engine, or operates an auxiliary machine such as an air conditioner, heater, audio equipment, car navigation system, and the auxiliary machine in operation This is a case where the load, particularly the load of the alternator, fluctuates greatly.

  FIG. 10 shows a control procedure according to this embodiment. First, prior to the timing for performing the first pattern missing tooth check, it is confirmed whether the operating state is normal or when a variation inducing factor is established (step S1). If the operating state is normal, x is selected as the predetermined value of the rotational speed, and x1 is selected as the predetermined value of the rotational speed when the fluctuation inducing factor is established. Subsequently, if the rotational speed is a predetermined value (x or x1) or if the gradient of the degree of decrease in the rotational speed is equal to or less than the predetermined slope θ (step S2), the first missing tooth check mask is removed. Execute (Step S3). As a result, fuel injection and ignition are continued as in the conventional control. On the other hand, when the rotational speed is still higher than the predetermined value (x or x1) and the rotational fluctuation value, in other words, the degree of decrease in the rotational speed is smaller than the predetermined gradient θ, the process is terminated. If the rotational speed exceeds the predetermined value (x or x1) or the rotational fluctuation value becomes smaller than the predetermined gradient θ when the first missing tooth check mask is being executed (step S4), the first missing tooth check mask is executed. The tooth check mask is released (step S5), and the process ends.

  With this configuration, in the present embodiment, the single missing tooth defect is a single missing tooth defect due to the extreme disturbance of the pulse signal related to the crank angle signal b caused by the rotational speed and the degree of decrease in the rotational speed. This effectively prevents the internal combustion engine from stalling without being recognized. Specifically, the fuel caused by misrecognizing that a single missing tooth is a missing missing tooth and erroneously determining that the correlation between the current cylinder position and the fuel injection and ignition timing is abnormal. It is possible to effectively prevent the internal combustion engine from stalling due to a further decrease in the rotational speed due to the stop of injection and ignition. As a result, stall during operation can be effectively avoided.

  Further, in this embodiment, in order to more effectively avoid erroneous cylinder discrimination during normal operation and further reduce the possibility of causing a stall, in the present embodiment, the predetermined value of the rotation speed is set to a fluctuation in the rotation speed. Is set to a predetermined value x1, which is higher than the normal value x.

  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-described embodiment, there is disclosed an aspect in which the requirement for inducing fluctuations in the rotational speed is only one stage, and only two types of predetermined values are applied. Alternatively, the predetermined value may be continuously changed according to the driving state. In addition, detailed modes such as specific cylinder discrimination, synchronous injection, fuel injection including asynchronous injection, and specific ignition timing are not limited to those of the above-described embodiment, but include various types including the existing ones. Embodiments 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 as a control device for an internal combustion engine that can determine the stroke of each cylinder in a timely manner.

0 ... Control unit (ECU)
762 ... Missing tooth portion b ... Crank angle signal x, x1 ... Predetermined value θ ... Predetermined gradient

Claims (2)

The crank angle sensor attached to the crankshaft outputs a crank angle signal as a pulse signal every time the crankshaft rotates by a unit angle, but does not output the pulse signal at a specific rotation phase angle of the crankshaft. It is what
Based on a single missing tooth defect in which the loss of the pulse signal occurs once independently during rotation of the crankshaft and a multiple missing tooth defect in which the loss of the pulse signal continuously occurs a plurality of times via the pulse signal. The control of the internal combustion engine that discriminates the stroke of each cylinder and stops the fuel injection and ignition when it is determined that the fuel injection and ignition timing for the cylinder are incorrect, and then starts the cylinder discrimination again. A device,
If the crankshaft rotation speed is less than a predetermined value or the gradient of the decrease in the rotational speed of the crankshaft is greater than or equal to a predetermined gradient in the cylinder discrimination performed during normal operation other than starting, the single missing tooth is A control apparatus for an internal combustion engine, which prohibits discrimination of a cylinder based on the determination.   2. The control device for an internal combustion engine according to claim 1, wherein the predetermined value of the rotational speed is set to be higher in an operating state in which a requirement for inducing fluctuations in the rotational speed is satisfied.

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