JP2017186988A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reverse rotation of an internal combustion engine by executing ignition start.SOLUTION: A control device of an internal combustion engine loaded on a vehicle which can automatically stop or restart an engine, includes a crank angle sensor outputting rotation pulse, a pulse width of which is changed according to a rotating direction of a crank shaft, and is constituted to execute ignition start performing fuel injection and ignition to a cylinder in an expansion stroke in restarting the engine. The ignition start is not executed as the rotating direction and the crank position are not determined, when a crank position non-determination flag is ON, and the ignition start is executed as the rotating direction and the crank position are determined when the crank position non-determination flag is OFF.SELECTED DRAWING: Figure 5

Description

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

  Conventionally, a vehicle capable of automatically stopping and restarting an internal combustion engine is known. For example, in Patent Document 1, when there is a restart request in the stop period from the fuel cut to the rotation stop of the internal combustion engine, the fuel is injected into the cylinder in the expansion stroke immediately before the stop of the internal combustion engine, and the rotation of the internal combustion engine It is disclosed that the internal combustion engine is restarted by igniting the cylinder in the expansion stroke after the direction is reversed from the positive direction.

Japanese Patent Laying-Open No. 2005-163612

  However, in the configuration of Patent Document 1, when using a crank angle sensor that changes the output time of the rotation pulse according to the rotation direction, if the ignition start is executed in a state where the rotation direction or crank position of the internal combustion engine is not fixed, an error occurs. There is a risk of starting ignition based on the rotation direction and the crank position. In this case, there is a possibility that the internal combustion engine is erroneously rotated in reverse by executing the ignition start.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for an internal combustion engine that can prevent the internal combustion engine from rotating backward due to execution of ignition start.

  The present invention relates to a control device for an internal combustion engine mounted on a vehicle capable of automatically stopping and restarting the internal combustion engine, and a crank angle sensor that outputs a rotation pulse having a pulse width changed according to the rotation direction of the crankshaft. Start control means for detecting the rotation direction and crank position of the crankshaft based on the rotation pulse, and performing ignition start for performing fuel injection and ignition to the cylinder in the expansion stroke when the internal combustion engine is restarted; The start control means does not execute the ignition start when the rotation direction and the crank position are not fixed, and executes the ignition start when the rotation direction and the crank position are fixed It is characterized by doing.

  In the present invention, the ignition start is not executed when the rotation direction and the crank position of the crankshaft are not fixed, and the ignition start is executed when the rotation direction and the crank position are fixed. It is possible to prevent reverse rotation of the internal combustion engine by execution.

FIG. 1 is a schematic configuration diagram schematically illustrating a control device for an internal combustion engine according to an embodiment. FIG. 2A is a diagram illustrating a rotation pulse output from the crank angle sensor during forward rotation. FIG. 2B is a diagram showing rotation pulses output from the crank angle sensor during reverse rotation. FIG. 3A is a diagram for explaining a method of calculating a crank position during forward rotation. FIG. 3B is a diagram for explaining a method of calculating a crank position during reverse rotation. FIG. 4 is a flowchart showing a method of determining the crank position undetermined state. FIG. 5 is a diagram for explaining a case where a reverse rotation pulse is input. FIG. 6 is a flowchart showing an ignition start execution process.

  Hereinafter, a control device for an internal combustion engine in an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram schematically showing a control device for an internal combustion engine in the embodiment. The vehicle Ve of the present embodiment includes an engine (ENG) 1 that is a power source, an automatic transmission (T / M) 2, an output shaft 3, a differential 4, an axle 5, and drive wheels 6. Yes. The power output from the engine 1 is transmitted from the crankshaft 1 a to the output shaft 3 via the automatic transmission 2, and is transmitted from the output shaft 3 to the axle 5 and the drive wheels 6 via the differential 4.

  The engine 1 is a four-cycle engine constituted by a known internal combustion engine, and is constituted by a direct injection type in which fuel is directly injected into each cylinder. The engine 1 is electrically controlled by a control device (ECU) 10 mounted on the vehicle Ve. Details of the control device 10 will be described later.

  The automatic transmission 2 is a known transmission that can automatically change the gear ratio, and is configured to be automatically set to a neutral state. Note that the vehicle Ve may include a torque converter that generates a torque amplification action by a fluid flow, and the engine 1 may be connected to the automatic transmission 2 via the torque converter so as to be able to transmit torque.

  The vehicle Ve is equipped with a starter (starter) 7 that starts the engine 1. The starting device 7 is constituted by an electric motor electrically connected to a battery (not shown), and is driven and controlled by the control device 10 when the engine is started.

  The vehicle Ve can automatically stop and restart the engine 1 under the control of the control device 10. Note that the power train of the vehicle Ve shown in FIG. 1 described above is an example. The vehicle on which engine 1 and control device 10 are mounted may be an FF vehicle or an FR vehicle.

  The control device 10 is constituted by an electronic control device that controls fuel injection and ignition timing to the engine 1. The control device 10 performs various calculations using signals input from various sensors mounted on the vehicle Ve and data stored in the storage device, and outputs a command signal as a result to the engine 1. 1 is controlled.

  As shown in FIG. 1, a sensor output signal is input from the crank angle sensor 20 to the control device 10. The crank angle sensor 20 detects the rotation direction and crank angle (crank position) of the engine 1 (crankshaft 1a), and outputs a signal in which the width of the timing pulse (output time) is changed according to the rotation direction. Further, the control device 10 receives signals from various sensors (not shown) (for example, an accelerator opening sensor, a brake stroke sensor, a vehicle speed sensor, a throttle opening sensor, etc.).

  Here, the rotation pulse output from the crank angle sensor 20 will be described. FIG. 2A is a diagram illustrating a sensor output signal when the crankshaft 1a is rotating forward. FIG. 2B is a diagram illustrating a sensor output signal when the crankshaft 1a rotates in the reverse direction. The sensor output signal shown in FIG. 2 represents a rotation pulse, and the timing rotor rotates integrally with the crankshaft 1a. The crank angle sensor 20 outputs a timing pulse (rotation pulse) synchronized with the rotational position of the crankshaft 1a in accordance with the rotation of the timing rotor. As shown in FIGS. 2A and 2B, the Lo output is used when the pulse is output. At that time, the crank angle sensor 20 detects the rotation direction of the crankshaft 1a, and changes the output time (pulse width) of the rotation pulse in accordance with the rotation direction. The rotation pulse relative to the rotation direction has a short pulse width during forward rotation and a long pulse width during reverse rotation. Thereby, the rotation pulse output from the crank angle sensor 20 includes information on the rotation direction. As shown in FIGS. 2A and 2B, the reverse rotation pulse width B, which is a pulse width during reverse rotation, has a longer pulse output period than the normal rotation pulse width A, which is a pulse width during forward rotation. In addition, since it is necessary to detect up to a higher rotational speed range during forward rotation than during reverse rotation, the pulse width is relatively shorter during forward rotation.

  The control device 10 controls the fuel injection and ignition timing to the engine 1 according to the vehicle state, and automatically stops and restarts the engine 1. As shown in FIG. 1, the control device 10 includes a start control unit 11 as a control unit that restarts the engine 1.

  For example, when it is determined that a predetermined stop condition is satisfied, the control device 10 performs engine stop control to automatically stop the engine 1. Examples of the stop condition include a case where the vehicle is temporarily stopped by waiting for a signal or the like, a case where the traveling vehicle is decelerating, or a case where the depression of the accelerator pedal is released while traveling at a certain high vehicle speed. The engine stop control includes fuel cut control for stopping fuel injection (supply) to the engine 1.

  The crank angle sensor 20 detects the crank angle (crank position) and the rotation speed of the engine 1 until the rotation of the engine 1 stops and also after the rotation of the engine 1 stops. As a result, the control device 10 determines the crank angle and the engine rotation based on the signal input from the crank angle sensor 20 from the start of fuel cut until the engine 1 stops rotating and after the engine 1 stops rotating. Speed and can be detected.

  When it is determined that the restart condition is satisfied after the engine 1 is automatically stopped, the start control unit 11 executes engine start control and restarts the engine 1. As a restart condition (start request), there is a charge request when it is detected that the accelerator pedal is depressed, when the brake pedal is released while the vehicle is stopped, or when the remaining battery capacity is reduced. There are some cases. Further, the start control unit 11 includes a determination unit that determines whether or not an input signal from various sensors including the crank angle sensor 20 is detected, and determines whether or not a restart condition is satisfied by the determination unit. be able to.

  The engine start control includes two controls, ignition start control and starter start control. The ignition start control is control for performing ignition (fuel injection and ignition) on the cylinder in the expansion stroke and rotating the crankshaft 1a by the combustion energy. On the other hand, the starter start control is control for rotating the crankshaft 1 a by consuming the battery power and driving the starter 7. When executing the starter start control, the control device 10 outputs a starter signal to drive the starter 7.

  The control device 10 uses a case where the engine 1 is started only by ignition start and a case where the engine 1 is started using both the ignition start and the starter 7 according to the vehicle state. For example, when there is a start request until the engine 1 stops rotating, the engine 1 is used only by the ignition start in which ignition is performed simultaneously with the fuel injection to the cylinder in the expansion stroke, or the ignition start and the starter 7 are used in combination. 1 is restarted.

  Further, at the time of starting ignition, the timing (piston position) at which fuel is injected into the cylinder in the expansion stroke differs depending on whether the crankshaft 1a is rotating forward or reversely. Therefore, the control device 10 is configured to detect the rotation direction of the crankshaft 1 a based on the rotation pulse input from the crank angle sensor 20.

  Further, as shown in FIGS. 3A and 3B, the control device 10 calculates the control crank position based on the rotation pulse input from the crank angle sensor 20. FIG. 3A is a diagram for explaining a method of calculating a crank position during forward rotation. FIG. 3B is a diagram for explaining a method of calculating a crank position during reverse rotation.

  As shown in FIG. 3A, when the input pulse width is the forward rotation pulse width A (when the forward rotation signal is input), the control device 10 adds the control crank position (crank position counter). At the time of forward rotation, the crank position counter is calculated to change by “+1”. In this case, the control device 10 determines whether or not the crankshaft 1a is rotating forward by determining whether or not the input pulse width is the forward rotation pulse width A.

  As shown in FIG. 3B, when the input pulse width is the reverse rotation pulse width B (when the reverse rotation signal is input), the control device 10 subtracts the control crank position (crank position counter). At the time of reverse rotation, the crank position counter is calculated to change by “−2”. In this case, the control device 10 determines whether or not the crankshaft 1a is rotating in reverse by determining whether or not the input pulse width is the reverse rotation pulse width B. Further, utilizing the characteristic that the reverse rotation pulse width B is longer than the forward rotation pulse width A, the control device 10 performs reverse rotation without waiting for the end of the pulse input when the forward rotation pulse width A is exceeded from the start of the pulse input. It can be determined that Specifically, the crank position counter is added (+1) to the output of the crank angle sensor 20 at the start of pulse input, and the pulse width is calculated at the end of the subsequent pulse input. When the calculated pulse width is the reverse rotation pulse width B, the crank position is specified by subtracting two (-2) crank position counters. The specified crank position information is used for fuel injection / ignition control (ignition start control) at the start of ignition.

  FIG. 4 is a flowchart showing a method of determining the crank position undetermined state. The control routine shown in FIG. 4 is repeatedly executed by the control device 10.

  As shown in FIG. 4, the control device 10 determines whether or not the crank angle sensor 20 has started outputting a rotation pulse (step S1). In step S1, it is determined whether or not input of a rotation pulse from the crank angle sensor 20 to the control device 10 has been started.

  When the crank angle sensor 20 starts outputting the rotation pulse (step S1: Yes), the control device 10 sets the crank position unconfirmed flag to ON (step S2), and adds the crank position calculation value (step S3). ). As a result, at the start of pulse input, the crank position unconfirmed flag is turned ON, and the crank position calculation value (crank position counter) is incremented by “+1”.

  When the crank angle sensor 20 does not start outputting the rotation pulse (step S1: No), the control device 10 determines whether or not the crank angle sensor 20 has finished outputting the rotation pulse (step S4). In step S4, it is determined whether or not the rotation pulse input to the control device 10 has ended. When the crank angle sensor 20 does not end the output of the rotation pulse (step S4: No), this control routine ends.

  When the crank angle sensor 20 finishes outputting the rotation pulse (step S4: Yes), the control device 10 sets the crank position unconfirmed flag to OFF (step S5). As a result, the crank position unconfirmed flag is turned OFF at the end of pulse input.

  And the control apparatus 10 determines whether a rotation direction is reverse rotation based on a pulse width (step S6). In step S6, the pulse width from the start of pulse input to the end of pulse input may be calculated to determine whether or not the calculated value is the reverse rotation pulse width B, or the elapsed time from the start of pulse input. It may be determined whether the time (pulse output period) exceeds the forward rotation pulse width A.

  When the rotation direction determined based on the pulse width is reverse rotation (step S6: Yes), the control device 10 subtracts the crank position calculation value (step S7). By step S7, the crank position calculation value is subtracted by “−2” at the end of pulse input. On the other hand, when the rotation direction determined based on the pulse width is not reverse rotation (step S6: No), this control routine ends.

  An example of the result of executing the control flow shown in FIG. 4 is shown in FIG. FIG. 5 is a diagram for explaining a case where a reverse rotation pulse is input. As shown in FIG. 5, at the time of reverse rotation, the crank position counter is incremented (+1) when the input of the rotation pulse is started, and the crank position unconfirmed flag is switched from OFF to ON. While the crank position undetermined flag is ON, the control device 10 does not perform fuel injection and ignition to the engine 1. That is, while the rotation pulse of the crank angle sensor 20 is being output (before the input is completed), the fuel is not injected into the cylinder in the expansion stroke because the crank position is not determined.

  When the rotation pulse input ends, the crank position counter is decremented (−2) and the crank position unconfirmed flag is switched from ON to OFF in order to determine that it is a reverse rotation pulse. When the crank position undetermined flag is OFF, the control device 10 can execute fuel injection and ignition to the engine 1.

  In addition, when the rotation direction is determined (when the input of the rotation pulse is completed), the crank position is also determined. Therefore, the second crank position counter that is updated after the crank position is determined is subtracted (-1). The second crank position counter does not change when the input of the rotation pulse is started. Then, since the crankshaft 1a continues to rotate in the reverse direction, the rotation pulse input start and input end are repeated, and the crank position counter and the second crank position counter are subtracted (advanced to the reverse rotation side).

  In this way, during the pulse output period, the crank position is indeterminate, and the execution of the control that requires the accuracy of the crank position including the ignition start control is stopped. The above-described determination method of the crank position undetermined state is applicable not only as fuel injection / ignition control but also as a determination method of the rotation direction in general control of the engine 1 using the rotation direction. The application can be realized by using different crank position information according to the control characteristics since the crank position information for adding or subtracting the crank position counter according to the pulse width is provided at the end of the pulse input.

  FIG. 6 is a flowchart showing an ignition start execution process. As shown in FIG. 6, the control device 10 determines whether or not the crank position unconfirmed flag is OFF (step S11). If the crank position unconfirmed flag is not OFF (step S11: No), the control device 10 does not execute the ignition start, and this control routine ends. That is, when the crank position undetermined flag is ON, the control device 10 does not perform fuel injection to the engine 1.

  On the other hand, when the crank position unconfirmed flag is OFF (step S11: Yes), the control device 10 determines whether or not the injection cylinder is within the injection range (step S12). In the process of step S12, it is confirmed whether the cylinder in the expansion stroke is in the injection range. Within the injection range means that the calculated value of the crank position (crank position counter) is within the required injection timing of the expansion stroke. When the injection cylinder is not within the injection range (step S12: No), this control routine ends.

  On the other hand, when the injection cylinder is within the injection range (step S12: Yes), the control device 10 executes fuel injection to the engine 1 (step S13) and executes an ignition instruction (step S14). The ignition start of the engine 1 is executed by steps S13 and S14. In the process of step S13, since the cylinder in the expansion stroke is in the injection range, fuel injection to the cylinder is executed. Further, a plurality of ignitions are performed by the ignition device based on the ignition instruction in step S14.

  As described above, the control device 10 does not execute the ignition start when the rotation direction and the crank position of the crankshaft 1a are not determined, and performs the ignition start when the rotation direction and the crank position are determined. Thereby, since the ignition start is not executed with the rotational direction and the crank position being undetermined, it is possible to prevent the engine 1 from being erroneously reversely rotated by executing the ignition start. Further, when the rotation direction of the crankshaft 1a is switched from the normal rotation to the reverse rotation, it is possible to prevent erroneous injection / ignition due to a delay in detection of the reverse rotation. Further, there is no restriction that the injection / ignition timing cannot be set near the top dead center in order to prevent erroneous injection / ignition.

1 Engine (ENG)
10 Control unit (ECU)
11 Start Control Unit 20 Crank Angle Sensor Ve Vehicle

Claims (1)

In a control device for an internal combustion engine mounted on a vehicle capable of automatically stopping and restarting the internal combustion engine,
A crank angle sensor that outputs a rotation pulse with a pulse width changed according to the rotation direction of the crankshaft;
Start control means for detecting a rotation direction and a crank position of the crankshaft based on the rotation pulse, and performing an ignition start for performing fuel injection and ignition to a cylinder in an expansion stroke when the internal combustion engine is restarted; Prepared,
The start control means includes
When the rotation direction and the crank position are not fixed, the ignition start is not executed,
The control device for an internal combustion engine, wherein the ignition start is executed when the rotation direction and the crank position are fixed.

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