JP2005180304A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a run-on phenomenon at the time of failure of start due to cranking. <P>SOLUTION: When cranking is stopped after failure of start, swing-back of a crankshaft occurs immediately before the stop. Since due to this swing-back, a POS signal is duplicatedly input, there is a possibility that simultaneous injection is continued after stop of cranking. In this invention, when intervals of the POS signal are abnormally long, it is determined that swing-back occurs, and ignition is stopped. When a cylinder discrimination error is determined based on the consistency with ignition order of numbers of discriminated cylinders, simultaneous injection is prohibited. Accordingly. the run-on phenomenon by automatic ignition of simultaneously injected fuel can be securely prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine that controls fuel injection or the like of the internal combustion engine, and more particularly to a technique for preventing a run-on phenomenon that rarely occurs when a start by cranking fails.

In Patent Document 1, a so-called sequential fuel injection device for a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder injects fuel sequentially at a predetermined crank angle during an intake stroke after each start. A technique is disclosed in which so-called simultaneous injection in which fuel is injected at the same time for all the cylinders is performed at the time of start cranking until the cylinder discrimination is completed. In other words, the cylinder discrimination performed based on the signal output from the crank angle sensor is not immediately completed at the time of start-up, so in the sequential injection performed after the completion of the cylinder discrimination, fuel supply is delayed, and smooth start-up becomes difficult. Become. For this reason, in the technique of Patent Document 1, simultaneous injection is performed immediately after the start of cranking, in which fuel injection is performed simultaneously for all cylinders at a certain timing.
JP-A-8-74622

  Since the above simultaneous injection is executed at a specific crank angle even before cylinder discrimination, when cranking is stopped after cranking and cranking is stopped, the crankshaft rotates in the reverse rotation direction immediately before the crankshaft stops. Even if there is a so-called rocking back that slightly returns, simultaneous injection may be executed at a certain crank angle based on the count of the POS signal output from the crank angle sensor for each unit crank angle. In rare circumstances, for example, in a situation where the temperature of the combustion chamber is high, such as warm-up restart, spontaneous ignition due to compression occurs without ignition, and the internal combustion engine remains at an incomplete combustion state at a low speed. A so-called run-on phenomenon that keeps rotating may occur.

  The present invention is intended to reliably avoid such an abnormal run-on phenomenon at the time of starting failure.

  The present invention includes a fuel injection valve for each cylinder, performs fuel injection for each cylinder at a predetermined crank angle of the cycle, and performs multiple cylinders at a predetermined time without waiting for completion of cylinder discrimination during start cranking. In the control device for an internal combustion engine that performs simultaneous injection to the engine, the crankshaft swing back when cranking is stopped is detected, and the simultaneous injection is prohibited when the swing back is detected.

  For example, the swing-back detection has a POS signal output means for outputting a POS signal for each unit crank angle as the crankshaft rotates. After cranking, the POS signal is detected at a time interval exceeding a predetermined criterion value When it is done, it can be detected as the above-mentioned swing back.

  By prohibiting simultaneous injection at the time of swingback detection in this way, the run-on phenomenon resulting from this simultaneous injection is reliably prevented.

  Furthermore, it has cylinder discrimination signal output means for outputting cylinder discrimination signals consisting of different numbers of pulse trains, and the cylinder discrimination signal obtained from the cylinder discrimination signal output means is a normal cylinder discrimination signal according to a predetermined ignition sequence and When they are different, it may be determined as a cylinder discrimination error, and simultaneous injection may be prohibited on the condition that the cylinder discrimination error is determined together with the above-described swing back detection.

  In addition, it is desirable to prohibit ignition by the spark plug at the time of swingback detection.

  According to the present invention, for example, when starting fails in warm-up restart, it is possible to reliably prevent a run-on phenomenon due to spontaneous ignition of simultaneously injected fuel.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an embodiment in which the present invention is applied to a V-type 8-cylinder gasoline internal combustion engine 1, in which an intake valve 3 is arranged inside the left and right banks, and an exhaust valve 4 is arranged outside.

  The exhaust manifolds 6 in the left and right banks are connected to a catalytic converter 7, and an air-fuel ratio sensor 8 that detects an exhaust air-fuel ratio is provided at an upstream position of the catalytic converter 7. The exhaust passages 9 of the left and right banks merge on the downstream side of the catalytic converter 7, and further include a second catalytic converter 10 and a silencer 11 on the downstream side.

  A branch passage 15 is connected to the intake port of each cylinder, and the upstream ends of the eight branch passages 15 are connected to the collector 16. An intake inlet passage 17 is connected to one end of the collector 16, and an electronically controlled throttle valve 18 is provided in the intake inlet passage 17. The electronically controlled throttle valve 18 includes an actuator composed of an electric motor, and its opening degree is controlled by a control signal supplied from an engine control unit 19. Note that a sensor (not shown) that detects the actual opening of the throttle valve 18 is integrally provided, and the throttle valve opening is closed-loop controlled to the target opening based on the detection signal. An air flow meter 25 that detects the intake air flow rate is disposed upstream of the throttle valve 18, and an air cleaner 20 is further disposed upstream. The branch passage 15 is provided with a fuel injection valve 23 for injecting fuel for each cylinder.

  In this embodiment, the Hall IC type POS sensor 21 and the PHASE sensor 22 are used in combination as the crank angle sensor. The POS sensor 21 is provided on the crankshaft and the PHASE sensor. 22 is provided for the exhaust-side camshaft 5 of one bank.

  Further, an accelerator opening sensor 12 for detecting an accelerator pedal opening (depression amount) operated by the driver is provided, and detection signals from these sensors are detected by the air flow meter 25 and the air-fuel ratio sensor 8. Along with the signal, it is input to the engine control unit 19. Based on these detection signals, the engine control unit 19 controls the injection amount and injection timing of the fuel injection valve 23, the ignition timing by the spark plug 24, the opening of the throttle valve 18, and the like. The control unit 19 receives a signal from the ignition key switch 13 in order to perform cranking at the start.

  FIG. 2 shows a pulse signal obtained by the crank angle sensor. The POS sensor 21 is a POS signal for each unit crank angle, specifically for every 10 ° CA as the crankshaft rotates. (Crank angle signal) is output. The POS signal has a missing portion corresponding to one pulse called “tooth missing” at four locations every 180 ° CA. Therefore, in this “tooth missing” portion, the two POS signals have an interval of 20 ° CA. Further, as shown in the figure, the PHASE signal (cylinder discrimination signal) output from the PHASE sensor 22 has four types of “3”, “4”, “2”, and “1” in order to perform cylinder discrimination. Are output every 180 ° CA. More specifically, the falling timing of the first (first) pulse in each pulse train is every 180 ° CA. This timing is 70 ° BTDC of the corresponding cylinder. Specifically, the leading pulse of the PHASE signal composed of three pulse trains corresponds to 70 ° BTDC of the # 1 cylinder. Note that both the POS signal and the PHASE signal are output as pulses having a certain width, but since the falling timing of the pulses is used, only the falling point is shown as a line having no width in FIG. As shown.

  Here, the POS sensor 21 outputs a pulse signal when the pickup portion detects a protrusion around the signal plate at the rear end of the crankshaft, and the protrusion is connected to the pickup portion regardless of the rotation direction of the crankshaft. Is crossed, a pulse signal (POS signal) is output. Similarly, the PHASE sensor 22 has a configuration in which the pickup portion detects the convex portion of the camshaft sprocket, and outputs a pulse signal (PHASE signal) corresponding to the passage of the convex portion regardless of the rotation direction.

  The ignition order of the V-type 8-cylinder internal combustion engine of this embodiment is in the order of # 1, # 8, # 7, # 3, # 6, # 5, # 4, and # 2, as shown. Therefore, each leading pulse of the PHASE signal corresponds to 70 ° BTDC of # 1, # 7, # 6, and # 4 cylinders. These points correspond to the center position of the “tooth missing” portion of the POS signal. In the POS signal, the presence of the “tooth missing” portion is divided into four pulse trains of 17 each, but the first pulse of the pulse train following the “tooth missing” portion is # 1, # 7, This corresponds to 60 ° BTDC for # 6 and # 4 cylinders. The 60 ° BTDC position of each cylinder is a reference in the ignition timing control, and is a “reference crank position (REF)” signal that is an internal signal for control as shown in FIG. Further, by dividing the REF signals of the # 1, # 7, # 6, and # 4 cylinders every 90 ° CA, the remaining REF signals of the # 8, # 3, # 5, and # 2 cylinders are generated. . Therefore, the entire REF signal is a signal at 90 ° CA intervals corresponding to 60 ° BTDC of the ignition cylinder.

  In the above configuration, the fuel injection from the fuel injection valve 23 is performed in each intake stroke for each cylinder as so-called sequential injection after the internal combustion engine is started. That is, fuel injection is sequentially performed in accordance with the ignition order based on cylinder discrimination as to which cylinder is in the intake stroke. On the other hand, at the time of engine start, in order to start quickly, simultaneous injection is performed in which fuel is injected all at once without waiting for completion of cylinder discrimination.

  The time chart of FIG. 3 explains fuel injection at the time of start-up. When the driver operates the ignition key switch 13 beyond the ON position to a predetermined start position, a starter motor (not shown) rotates. Cranking starts. Accordingly, a cranking determination flag indicating that cranking is being performed is turned ON. This cranking determination does not necessarily correspond to the actual operation of the starter motor, as will be described later. Then, after the cranking starts, when the reference crank position is reached, simultaneous injection (denoted as simultaneous injector output in the figure) is performed based on the REF signal. This simultaneous injection is thereafter performed every 360 ° CA. As described above, when the internal combustion engine is started by this simultaneous injection, the system shifts to sequential injection.

  On the other hand, if cranking is performed for a short time but the engine does not start and the driver returns the ignition key switch 13 from the start position to the ON position, the starter motor is turned off and the rotation of the crankshaft is stopped. At this time, at the moment when the rotation of the crankshaft stops, a so-called swinging phenomenon that the crankshaft slightly rotates in the reverse rotation direction may occur due to the compression pressure in the cylinder or the reaction force of the valve spring. FIG. 3 illustrates erroneous detection of the POS signal and the PHASE signal when such a swingback occurs. That is, in this example, immediately after the third pulse of the PHASE signal composed of three pulse trains is output, the crankshaft swings back and the camshaft also rotates in the reverse direction. A signal (PHASE signal) is output, and as a result, five pulse trains are continuously input. In addition, the POS signal also exhibits a behavior as if a pulse signal (POS signal) is generated in an overlapping manner due to reverse rotation of the crankshaft, and the crankshaft continues to rotate in the normal direction. . Therefore, in the prior art, simultaneous injection may continue even if the ignition key switch 13 is returned to the ON position, and there is a possibility of a run-on phenomenon as described above.

  In this embodiment, when the swingback is detected, the swingback determination flag is turned on, thereby inhibiting the ignition of each cylinder. Then, when it is determined that the cylinder discrimination error is caused by swinging back as will be described later, the cylinder discrimination error determination flag is turned ON. For example, in the example shown in the figure, five pulse trains that are not possible are input as PHASE signals, so that it is determined that there is a cylinder discrimination error at the next REF position. Thus, when the three conditions of cranking determination, swingback determination, and cylinder determination error determination are satisfied at the same time, simultaneous injection is prohibited. As a result, simultaneous injection is not performed thereafter, and the run-on phenomenon due to spontaneous ignition is reliably prevented.

  Next, specific details of the control will be described based on the flowcharts of FIGS.

  FIG. 4 is a main flowchart relating to the control of the simultaneous injection at the start. First, in step 1, it is determined whether the ignition key switch 13 is ON. If the ignition key switch 13 is not ON, the process is terminated. If the ignition key switch 13 is ON, it is determined in step 2 whether or not cranking determination is in progress, that is, whether or not the above-described cranking determination flag is ON. As described above, the starter motor is driven when the driver turns the ignition key switch 13 to the start position. If the cranking determination flag is ON, the process proceeds to step 3 to determine whether or not the first REF position has been detected. If the first REF position is detected, the process proceeds to step 4 to determine whether the swingback determination flag is ON. If not, simultaneous injection is permitted in step 6. As a result, as described with reference to FIG. 3, simultaneous injection is executed at the first REF position, and simultaneous injection every 360 ° CA is allowed.

  If the swingback determination flag is ON, the process proceeds to step 5 to determine whether the cylinder determination error determination flag is ON. If not, simultaneous injection is permitted in step 6. On the other hand, if the cylinder determination error determination flag is ON, the process proceeds to step 7 to prohibit simultaneous injection. That is, on the condition that cranking determination is being performed in step 2, simultaneous injection is prohibited only when both the swingback determination flag in step 4 and the cylinder determination error determination flag in step 5 are ON.

  FIG. 5 is a flowchart showing a subroutine for cranking determination in step 2 above. In step 11, it is determined whether or not the ignition key switch 13 is ON. If it is ON, the process proceeds to step 12, and it is determined whether or not the internal combustion engine is in a non-rotating state at that time. If the non-rotation state is recognized, it is determined in step 13 and step 14 whether a POS signal or a PHASE signal has been input. If any signal is detected, it means that the crankshaft has started to rotate from the stopped state, so the routine proceeds to step 15 where it is determined that cranking is in progress. If the internal combustion engine is already rotating at step 12, the engine speed is equal to or lower than a predetermined speed N1 (this is set to a value lower than the idle speed) at step 16, When the battery voltage is equal to or lower than the predetermined voltage V1 (that is, a state in which the voltage is reduced due to the drive of the starter motor), the process proceeds to step 15 and the cranking determination flag is maintained ON.

  After step 15, the cranking continuation timer is incremented at step 18, and the determination of the cranking determination cancellation condition at steps 19 to 21 is repeated. In step 19, it is determined whether or not the battery voltage is equal to or higher than a predetermined voltage V2 close to the reference voltage. If the voltage is equal to or higher than voltage V2, the process proceeds to step 22 and the cranking continuation timer is cleared. At the same time, the ON state of the cranking determination flag ends. In step 20, it is determined whether the value of the cranking continuation timer is within the specified time T1, and if it exceeds the specified time T1, the process similarly proceeds to step 22. In step 21, it is determined whether the engine speed is equal to or lower than a predetermined speed N2 set to an extent exceeding the idle speed. If the engine speed exceeds the predetermined speed N2, the process proceeds to step 22 in the same manner. That is, the cranking determination flag is turned off when the predetermined time T1 has elapsed, or when the battery voltage is recovered (that is, it is considered that the starter motor is turned off), or when the engine speed is set to stand-alone operation. Even when it becomes sufficiently high, it is turned OFF.

  FIG. 6 is a flowchart showing a subroutine for determining whether to swing back in step 4. In step 31, it is determined whether the ignition key switch 13 is ON. If it is ON, the routine proceeds to step 32, where it is determined whether the engine speed is equal to or less than a predetermined engine speed N3. This rotational speed N3 is set to a value lower than the idle rotational speed capable of independent operation. If “YES” in the step 32, the process proceeds to a step 33 to determine whether the interval of the POS signals is longer than the predetermined time T2. The above-described time T2 corresponds to a time interval that is not normally possible including the “tooth missing” portion of the POS signal. As described above, when the same pulse appears repeatedly due to the crankshaft swinging back. The time interval that can only occur is set. Accordingly, when a time interval larger than the time T2 is detected here, the routine proceeds to step 34, where it is determined to swing back.

  After step 34, the timer after the swingback determination is incremented in step 35, and the determination of the swingback determination cancellation condition in steps 36 and 37 is repeated. In step 36, it is determined whether the value of the timer after swingback determination is less than the specified time T3. If it is equal to or longer than the specified time T3, the process proceeds to step 38, and the timer after swingback determination is cleared. At the same time, the ON state of the swingback determination flag ends. In step 37, it is determined whether or not it is within the prescribed time T4 since the last detection of the REF position. If the prescribed time T4 is exceeded, the routine proceeds to step 38 in the same manner. In other words, the swing-back determination flag is turned OFF when a certain time T3 has elapsed since it was determined to swing back, or the internal combustion engine is completely stopped after a certain time T4 has elapsed since the rotation of the crankshaft stopped. When it is determined that it has been performed, it is turned OFF.

  FIG. 7 is a flowchart showing a subroutine of cylinder discrimination error determination in step 5. The cylinder discrimination itself based on the pulse train count of the PHASE signal is processed by another subroutine (not shown).

  In step 41, it is determined whether the ignition key switch 13 is ON. If ON, the process proceeds to step 42 and waits for the input of the POS signal. If a POS signal is input, the process proceeds to step 43 to determine whether the cycle of the current POS signal is 1.5 times or more than the cycle of the previous POS signal. If the current cycle is 1.5 times or more of the previous time, it is determined that the “tooth missing” portion has passed, and in step 44, the falling edge of the current POS signal is set to the REF position, and in step 45, The POS counter that counts the number of pulses of the POS signal is cleared. In step 46, it is determined whether the current cylinder has been determined, that is, whether the cylinder discrimination has already been completed. If the cylinder discrimination is not completed, the routine is repeated until the next REF position is detected.

  If the cylinder discrimination has been completed, the routine proceeds from step 46 to step 47, where cylinder discrimination is performed from the number of pulses of the PHASE signal immediately before that. Specifically, if the number of pulses is “3”, it is # 7 cylinder, if it is “4”, it is # 6 cylinder, if it is “2”, it is # 4 cylinder, if it is “1”, it is # 1 cylinder. . If the number of pulses is “0” or “5 or more”, the # 0 cylinder is selected. In step 48, it is determined whether the determined cylinder is other than "# 0 cylinder". If it is “# 0 cylinder”, since it is an abnormal value, the routine proceeds to step 49, where it is determined as a cylinder discrimination error. If it is other than “# 0 cylinder”, the routine proceeds to step 50, where the consistency with the previous discriminated cylinder is determined according to the ignition order. That is, if the current discriminating cylinder is the # 7 cylinder, it is determined whether or not the previous discriminating cylinder is the # 8 cylinder. Similarly, when the current discriminating cylinder is the # 6, # 4, # 1 cylinder, it is determined whether the previous cylinder is the # 3, # 5, # 2 cylinder, respectively. Here, if it is not aligned with the previous cylinder in the ignition order, the routine proceeds to step 49, where it is determined as a cylinder discrimination error.

  On the other hand, if NO in step 43, that is, if the POS signal has an interval of 10 ° CA, the process proceeds to step 51 and the POS counter is incremented. If it is determined in step 52 that the value of the POS counter has become "9" or more, the process proceeds to step 53, where the current POS signal falls to the REF position, and in step 54, the POS counter is cleared. Next, in step 55, it is determined whether the previous REF position, that is, the REF position two times before, has been confirmed. If so, the process proceeds to step 56, and between the previous REF position and the current REF position. Cylinder discrimination is performed from the detected number of pulses of the PHASE signal. Specifically, if the number of pulses is “1”, it is # 2 cylinder, if it is “3”, it is # 8 cylinder, if it is “4”, it is # 3 cylinder, if it is “2”, it is # 5 cylinder. . If the number of pulses is “0” or “5 or more”, the # 0 cylinder is selected. In step 57, it is determined whether the determined cylinder is other than “# 0 cylinder”. If it is “# 0 cylinder”, since it is an abnormal value, the routine proceeds to step 49, where it is determined as a cylinder discrimination error. If it is other than “# 0 cylinder”, the routine proceeds to step 58 where consistency with the previous discriminating cylinder is determined according to the ignition order. That is, if the current discriminating cylinder is the # 2 cylinder, it is determined whether or not the previous discriminating cylinder is the # 4 cylinder. Similarly, when the current discriminating cylinder is the # 8, # 3, # 5 cylinder, it is determined whether the previous cylinder is the # 1, # 7, # 6 cylinder, respectively. Here, if it is not aligned with the previous cylinder in the ignition order, the routine proceeds to step 49, where it is determined as a cylinder discrimination error.

  By making such cylinder discrimination error determination one of the AND conditions for prohibiting simultaneous injection, for example, when the driver performs cranking again immediately after determining the swing back, cancellation of the swing back determination ( Simultaneous injection is allowed without waiting for the flag to be turned off, and normal starting can be immediately performed.

  As mentioned above, although one Example which applied this invention to the V type 8 cylinder internal combustion engine was described, this invention is not limited to this, It can apply to the internal combustion engine of various cylinder numbers. Further, the specific configuration of the crank angle sensor is not limited to the above embodiment. Further, in the above-described embodiment, the REF signal is generated as an internal signal by “missing teeth” of the POS signal. However, it is also possible to configure such that the crank angle sensor directly outputs this signal.

1 is a system configuration diagram of a V-type 8-cylinder internal combustion engine as an embodiment of the present invention. The time chart which shows the output signal of a crank angle sensor. The time chart which shows the control etc. of the simultaneous injection after a start. The flowchart which shows the simultaneous injection control in this Example. The flowchart which shows the subroutine of cranking determination. The flowchart which shows the subroutine of a swingback determination. The flowchart which shows the subroutine of cylinder discrimination | determination error determination.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 19 ... Engine control unit 21 ... POS sensor 22 ... PHASE sensor 23 ... Fuel injection valve

Claims (4)

Each cylinder is equipped with a fuel injection valve, and each cylinder performs fuel injection at a predetermined crank angle of the cycle, and at the time of start cranking, simultaneous injection to a plurality of cylinders at a predetermined time without waiting for completion of cylinder discrimination In a control device for an internal combustion engine that performs
A control device for an internal combustion engine, wherein a crankshaft swingback when cranking is stopped is detected, and simultaneous injection is prohibited when the swingback is detected.   POS signal output means for outputting a POS signal for each unit crank angle with the rotation of the crankshaft, and when the POS signal is detected at a time interval exceeding a predetermined criterion value after cranking, 2. The control device for an internal combustion engine according to claim 1, wherein the control is detected as a return.   When cylinder discrimination signal output means for outputting cylinder discrimination signals comprising different numbers of pulse trains is provided, and the cylinder discrimination signal obtained from the cylinder discrimination signal output means is different from a normal cylinder discrimination signal according to a predetermined ignition sequence 3. The control apparatus for an internal combustion engine according to claim 1 or 2, wherein it is determined as a cylinder discrimination error, and simultaneous injection is prohibited on the condition that the cylinder discrimination error is determined together with the above-described swing back detection. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein ignition by a spark plug is prohibited when swingback is detected.

Images