JP2013151910A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To start an internal combustion engine even if a crank angle signal cannot be received in a start-up of the internal combustion engine.SOLUTION: A cam angle sensor outputs a cam angle signal in an angle unit formed by dividing one revolution of a camshaft by the number of cylinders and also outputs a cylinder discrimination signal expressing a timing suitable for the ignition in a specific cylinder. In a start-up of an internal combustion engine, when a crank angle signal cannot be received, the specific cylinder is ignited on the basis of the timing of the cylinder discrimination signal. A time difference (t) between the cylinder discrimination signal and a nearest cam angle signal are measured, and in the ignition of the other cylinder coming hereafter, the cylinder is ignited on the basis of a timing when the time difference (t) elapses from the next cam angle signal.

Description

  The present invention relates to a control device that controls an internal combustion engine.

  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.

  The crankshaft of the internal combustion engine is provided with a crank angle sensor for detecting the rotation angle and the engine speed. The crank angle sensor senses the rotation of the rotor fixed to the crankshaft. Teeth are formed on the outer periphery of the rotor every 10 ° CA (crank angle). The crank angle sensor faces the outer periphery of the rotor, detects that each tooth passes near the sensor, and outputs a pulse signal (crank angle signal) each time. Normally, the crankshaft rotor teeth are partially missing, and it is possible to know the absolute angle of the crankshaft based on the missing crank angle signal pulses due to the missing teeth. Yes.

  Cam angle sensors are also attached to camshafts that open and close the intake valves or exhaust valves of each cylinder. The cam angle sensor also senses the rotation of the rotor fixed to the camshaft. In this rotor, teeth or protrusions are formed at an angle obtained by dividing one rotation by the number of cylinders, or 120 ° (240 ° CA in terms of crank angle) in the case of a three-cylinder engine. Each time passes through the vicinity of the cam angle sensor, the cam angle sensor outputs a pulse signal (cam angle signal).

  The cam angle signal is a signal indicating that any of the plurality of cylinders has reached a predetermined stroke. However, when a variable valve timing mechanism is attached to the intake camshaft or the exhaust camshaft, it is also a signal indicating the valve timing that the variable valve timing mechanism is embodied. For example, when a variable valve timing mechanism and a cam angle sensor exist on the intake camshaft side, the cam angle signal suggests that the intake stroke is started in any cylinder, and the intake valve of the cylinder The timing for opening the valve is also shown. In this case, the phase of the cam angle signal relative to the crank angle signal is advanced or retarded by operation of the variable valve timing mechanism.

  An ECU (Electronic Control Unit), which is a control device for an internal combustion engine, receives a crank angle signal and a cam angle signal, refers to both signals to grasp the stroke of each cylinder, and determines the fuel injection timing and ignition timing in the cylinder. To control the operation of the internal combustion engine (see the following patent document). It is the same when starting the internal combustion engine that the current stroke of each cylinder must be known to perform fuel injection and ignition.

  By the way, although extremely rare, the ECU may not be able to receive the crank angle signal due to the disconnection of the transmission path between the crank angle sensor and the ECU or the failure of the crank angle sensor itself. If the crank angle signal cannot be received, there is nothing else but to determine the ignition timing based on the cam angle signal. In other words, a pseudo crank angle signal is generated by dividing the cam angle signal that is visited at every fixed rotation angle, and the ignition timing is determined based on the pseudo crank angle signal.

  However, the above-described method is difficult to apply when starting the internal combustion engine. During cranking in which the engine is rotationally driven by a starter motor (cell motor), the rotational speeds of the crankshaft and the camshaft that follows the crankshaft frequently fluctuate. Even during the rotation of about 240 ° CA, the camshaft rotates at a high speed or a low speed. Therefore, even if the ignition timing is determined by dividing the cam angle signal, it is not guaranteed that the timing is suitable for ignition in the cylinder, and the fuel in the mixture cannot be ignited and started. There was a risk of falling into a defect.

JP 2005-207394 A

  An object of the present invention is to enable an internal combustion engine to be started even if a crank angle signal cannot be received when the internal combustion engine is started.

  In the present invention, a crank angle signal output from a crank angle sensor that detects a rotation angle of the crankshaft in a predetermined angle unit, and a rotation angle of the camshaft is detected in an angle unit obtained by dividing one rotation of the camshaft by the number of cylinders. In a control device for controlling an internal combustion engine with reference to a cam angle signal output from a cam angle sensor, a cylinder discrimination that represents a timing suitable for ignition in a specific cylinder in addition to the cam angle signal is added to the cam angle signal If the crank angle signal cannot be received when the internal combustion engine is started, the ignition is performed based on the timing of the cylinder discrimination signal when the specific cylinder is ignited, and the cylinder discrimination signal is the closest to the cylinder discrimination signal. The time difference from the cam angle signal is measured, and the timing at which the time difference elapses from the next cam angle signal when the other cylinders that come after that are ignited It was decided to carry out the ignition to the reference.

  According to the present invention, the internal combustion engine can be started even if the crank angle signal cannot be received when the internal combustion engine is started.

The figure which shows schematic structure of the internal combustion engine 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 which shows the content of the ignition control which the control apparatus of the embodiment implements at the time of starting of an 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. The internal combustion engine of the illustrated example is of an in-cylinder direct injection type, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1), an injector 10 for injecting fuel into each cylinder 1, An intake passage 3 for supplying intake air to each cylinder 1, an exhaust passage 4 for discharging exhaust from each cylinder 1, an exhaust turbocharger 5 for supercharging intake air flowing through the intake passage 3, and exhaust An external EGR device 2 that recirculates EGR gas from the passage 4 toward the intake passage 3 is provided.

  A spark plug 13 is attached to the ceiling of the combustion chamber of the cylinder 1. The spark plug 13 receives spark voltage generated by the ignition coil and causes a 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 valve 11 is accompanied by a variable valve timing mechanism 111 that can change the opening / closing timing thereof. The variable valve timing mechanism 111 advances or retards the opening / closing timing of the intake valve 11 by, for example, changing the rotational phase of the intake camshaft with respect to the crankshaft.

  The intake passage 3 takes in air from the outside and guides it to the intake port of the cylinder 1. On the intake passage 3, an air cleaner 31, a compressor 51 of the supercharger 5, an intercooler 32, an electronic throttle valve 33, a surge tank 34, and an intake manifold 35 are arranged in this order from the upstream side.

  The exhaust passage 4 guides the exhaust generated by burning the fuel in the cylinder 1 from the exhaust port of the cylinder 1 to the outside. An exhaust manifold 42, a drive turbine 52 for the supercharger 5, and a three-way catalyst 41 are disposed on the exhaust passage 4. In addition, an exhaust bypass passage 43 that bypasses the turbine 52 and a waste gate valve 44 that is a bypass valve that opens and closes the inlet of the bypass passage 43 are provided. The waste gate valve 44 is an electric waste gate valve that can be opened and closed by inputting a control signal l to the actuator, and a DC servo motor is used as the actuator.

  The exhaust turbocharger 5 is configured such that the drive turbine 52 and the compressor 51 are connected and linked in a coaxial manner. Then, the driving turbine 52 is rotationally driven by using the energy of the exhaust gas, and the compressor 51 is pumped by using the rotational force, whereby the intake air is pressurized and compressed (supercharged) and sent to the cylinder 1.

  The external EGR device 2 realizes a so-called high-pressure loop EGR. The inlet of the external EGR passage is connected to a predetermined location upstream of the turbine 52 in the exhaust passage 4. The outlet of the external EGR passage is connected to a predetermined location downstream of the throttle valve 33 in the intake passage 3, specifically to a surge tank 34. An EGR cooler 21 and an EGR valve 22 are also provided on the external EGR passage.

  The ECU 0 as the control device for the internal combustion engine 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 of the ECU 0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the vehicle speed, an N signal b that is a crank angle signal output from a crank angle sensor that detects the rotation angle of the crankshaft and the engine speed, and an accelerator pedal. The accelerator opening signal c output from the accelerator opening sensor that detects the amount of depression of the engine or the opening of the throttle valve 33 as the accelerator opening (so-called required load), and the intake in the intake passage 3 (particularly, the surge tank 34). An intake air temperature signal d output from a temperature sensor that detects air temperature, an intake air pressure signal e output from a pressure sensor that detects intake air pressure (or supercharging pressure) in the intake passage 3, and a cooling water temperature of the internal combustion engine are detected. The coolant temperature signal f output from the coolant temperature sensor, and the cam angle signal output from the cam angle sensor at a plurality of cam angles of the intake camshaft G signal and encompass finely cylinder discrimination signal g, the vibration, the knocking signal h or the like to be output from the knock sensor for detecting a change in the noise or the combustion pressure is input occurring in the combustion chamber.

  From the output interface of the ECU 0, an ignition signal i for the igniter, an opening / closing timing control (phase angle) signal j for the variable valve timing mechanism 111, an opening operation signal k for the throttle valve 33, and a waste gate valve 44 On the other hand, an opening operation signal l, an opening operation signal m for the EGR valve 22, a fuel injection signal n for the injector 10, a control signal o for controlling the driving of the starter motor, and the like are 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, and knows the intake pressure and the engine speed, and the cylinder 1 The amount of intake air charged in the engine is estimated, and the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, opening / closing timing of the intake valve 11, EGR amount ( Alternatively, various operation parameters such as the EGR rate and the opening degree of the EGR valve 22 are determined. The ECU 0 applies various control signals i, j, k, l, m, and n corresponding to the operation parameters via the output interface.

  Further, the ECU 0 inputs a control signal o to the starter motor when the internal combustion engine is started (a cold start or a return from an idling stop), and the starter motor pinion gear is used as a flywheel. (MT vehicle) or drive plate (AT vehicle) is engaged with a ring gear on the outer periphery to perform cranking for rotating the engine. Cranking ends from the first explosion to the consecutive explosion, and ends when the engine speed exceeds a threshold determined according to the cooling water temperature or the like (assuming that the explosion has been completed).

  Hereinafter, the crank angle signal output from the crank angle sensor, the cam angle signal output from the cam angle sensor, and the cylinder discrimination signal will be described in detail. The crank angle sensor senses the rotation angle of the rotor 7 that is fixed to the crankshaft and rotates integrally with the crankshaft. As shown in FIG. 2, teeth 71 are formed on the rotor 7 at a predetermined angle, for example, every 10 ° CA. The crank angle sensor detects that each tooth 71 of the rotor 7 passes in the vicinity of 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 71 of the crankshaft rotor 7 are partially missing, and due to the missing teeth, the crank angle signal pulse is also partially missing as shown in FIG. In the example shown in FIGS. 2 and 4, pulses corresponding to the 17th, 18th, 20th, 21st, 35th and 36th 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, the timing of the nineteenth pulse following the missing eighteenth pulse is 180 ° CA. The pulse indicating the timing of 0 ° CA is equal to the compression top dead center of the cylinder 1 or offset forward from the compression top dead center within a range of about 10 ° CA.

  On the other hand, the cam angle sensor senses the rotation angle of the rotor 8 that is fixed to the camshaft and rotates integrally with the camshaft. As shown in FIG. 3, the rotor 8 is formed with protrusions 81 at every angle obtained by dividing one rotation of the camshaft by the number of cylinders. In the case of a three-cylinder engine, the protrusion 81 is arranged every 120 ° (240 ° CA in terms of crank angle). The cam angle sensor detects that each protrusion 81 passes in the vicinity of the sensor, and transmits a pulse signal as a cam angle signal each time.

  Further, the cam angle sensor outputs a cylinder discrimination signal once every time the camshaft rotates once. The rotor 8 is provided with a cylinder discrimination signal projection 82 in addition to the cam angle signal projection 81, and a pulse that becomes a cylinder discrimination signal when the projection 82 passes in the vicinity of the cam angle sensor. Send a signal.

  The cam angle signal is a signal indicating that any one of the cylinders 1 has reached a predetermined stroke. In this embodiment, a cam angle sensor is attached to the intake camshaft, and the cam angle signal indicates the start of the intake stroke in each cylinder 1 as shown in FIG. In addition, the cam angle signal represents the valve opening timing of the intake valve 11 adjusted by the variable valve timing mechanism 111.

  The cylinder discrimination signal indicates in which cylinder 1 the intake stroke suggested by the cam angle signal is. In the example shown in FIG. 4, a pulse of the cylinder discrimination signal is output after the start of the intake stroke of the first cylinder 1 and before the start of the intake stroke of the second cylinder 1, and the pulse of the cam angle signal immediately before that is output. Is the start of the intake stroke in the first cylinder 1 (or the pulse of the cam angle signal immediately after that is the start of the intake stroke in the second cylinder 1).

  The phases of the cam angle signal and the cylinder discrimination signal are changed by the advance / retard operation of the opening / closing timing of the intake valve 11 by the variable valve timing mechanism 111. In the present embodiment, the reference phase is a state where the opening timing of the intake valve 11 is most retarded, that is, an operating region where the engine speed is low (including idling) or engine start. The cam angle signal and cylinder discrimination signal shown in FIG. 4 are for the reference phase. When the engine speed increases and the opening timing of the intake valve 11 advances, the output timing of the cam angle signal and the cylinder discrimination signal is advanced. That is, the phases of the cam angle signal and the cylinder discrimination signal are shifted leftward in FIG.

  Therefore, in the present embodiment, the cylinder discrimination signal of the reference phase is set so as to represent the timing suitable for ignition in the specific cylinder 1. In the example shown in FIGS. 3 and 4, the protrusion 82 of the rotor 8 is arranged so that a cylinder discrimination signal is output at a timing suitable for ignition of the third cylinder 1, and the cylinder discrimination is performed from the cam angle sensor at that timing. A signal pulse is transmitted.

  If the transmission path between the crank angle sensor and the ECU 0 is broken or the crank angle sensor itself fails and the ECU 0 cannot receive the crank angle signal, it can still be received to start the internal combustion engine. It is necessary to determine the fuel injection timing and the ignition timing based on the cam angle signal and the cylinder discrimination signal.

  By referring to both the cam angle signal and the cylinder discrimination signal, it is easy to know which cylinder 1 has started the intake stroke. Regarding the fuel injection at the time of starting, a required amount of fuel may be injected from the injector 10 of the cylinder 1 at the timing after reception of the cam angle signal related to the cylinder 1 in which the intake stroke is started.

  On the other hand, for ignition at the time of starting, first, when the third cylinder 1 is ignited, the ignition may be performed when the cylinder discrimination signal is received. Then, the ECU 0 measures the time difference t between the cam angle signal that suggests the start of the intake stroke of the first cylinder 1 and the cylinder discrimination signal that comes after that.

  When the next first cylinder 1 is ignited, the cam angle signal indicating the start of the intake stroke of the second cylinder 1 is received, and then the ignition is performed at the timing when the measured time difference t has elapsed. . Similarly, when the next second cylinder 1 is ignited, the ignition is performed at the timing when the time difference t has elapsed since the cam angle signal indicating the start of the intake stroke of the third cylinder 1 is received.

  Further, when the third cylinder 1 is subsequently fired, ignition is performed when the cylinder discrimination signal is received, and the cylinder discrimination signal and the latest cam angle signal (this is the start of the intake stroke of the first cylinder 1). The time difference t from the above is measured again. The measured time difference t is used to determine the ignition timing in the first cylinder 1 and the second cylinder 1 thereafter.

  In the present embodiment, a crank angle signal output from a crank angle sensor that detects a rotation angle of the crankshaft in a predetermined angle unit, and a rotation angle of the camshaft in an angle unit obtained by dividing one rotation of the camshaft by the number of cylinders. The internal combustion engine is controlled with reference to a cam angle signal output from a cam angle sensor to be detected. The cam angle sensor is added to the cam angle signal, and a timing suitable for ignition in a specific cylinder 1 is determined. If the crank angle signal cannot be received when the internal combustion engine is started, the ignition is performed based on the timing of the cylinder discrimination signal when the specific cylinder 1 is ignited. The time difference t between the discrimination signal and the latest cam angle signal is measured, and the time difference t has elapsed from the next cam angle signal when the other cylinders 1 that come after that are ignited. Timing to constitute a control device 0 which is characterized in that the ignition based on.

  According to this embodiment, when the internal combustion engine is started, the cam angle signal and the cylinder output from the cam angle sensor even under a situation where the rotation speed of the crankshaft and the camshaft frequently fluctuates during cranking. It is possible to set an appropriate ignition timing with reference to the determination signal. Therefore, even if the crank angle signal cannot be received, a fail safe is realized in which the internal combustion engine can be started reliably.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, the cam angle sensor is provided on the intake camshaft side, but this does not hinder the aspect in which the cam angle sensor is provided on the exhaust camshaft side. In particular, when the variable valve timing mechanism is attached to the exhaust valve 12, a cam angle sensor for detecting the rotational phase of the exhaust camshaft and the valve timing of the exhaust valve 12 is essential. The cam angle signal in this case indicates, for example, the start of the exhaust stroke in each cylinder 1 and represents the opening timing of the exhaust valve 12.

  It goes without saying that the number of cylinders of the internal combustion engine is not limited to three cylinders.

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

  The present invention can be applied to control at the start of a spark ignition type internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Intake valve 111 ... Variable valve timing mechanism b ... Crank angle signal (N signal)
g: Cam angle signal and cylinder discrimination signal (G signal)

Claims (1)

A crank angle signal output from a crank angle sensor that detects a rotation angle of the crankshaft in a predetermined angle unit, and a cam angle sensor that detects a rotation angle of the camshaft in an angle unit obtained by dividing one rotation of the camshaft by the number of cylinders. A control device for controlling the internal combustion engine with reference to the cam angle signal output from
In addition to the cam angle signal, the cam angle sensor also outputs a cylinder discrimination signal indicating timing suitable for ignition in a specific cylinder,
If the crank angle signal cannot be received when the internal combustion engine is started, the ignition of the specific cylinder is performed based on the timing of the cylinder discrimination signal, and the time difference between the cylinder discrimination signal and the latest cam angle signal is calculated. A control apparatus for an internal combustion engine, characterized in that the ignition is performed with reference to a timing at which the time difference has elapsed from the next cam angle signal when the other cylinders that are measured thereafter are ignited.

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