JP2017002826A - Engine stop/start controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine stop/start controller capable of shortening a power supply period of a starter and suppressing increase of battery power consumption and deterioration of the starter.SOLUTION: An engine stop/start controller is applied to a system including an engine 11, and a starter 14 driven by power supply from a battery 20 and configured to impart initial rotation to the engine 11. The engine stop/start controller includes: combustion determination means of determining presence/absence of combustion in a combustion chamber 19 by a rotational speed from a compression upper dead point of the engine 11 or a change amount of in-cylinder pressure after the starter 14 imparts the initial rotation, in engine start; and power supply control means of stopping power supply to the starter 14 on the basis of such determination of the combustion determination means that combustion has been performed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine stop / start control device.

  Generally, when the engine is started from a stopped state, an initial rotation is applied to the output shaft of the engine by the starting device. Specifically, when power supply to the motor included in the starter is started, the crankshaft is rotated by the rotational force of the motor, and the engine is started. In such a case, there is a technique in which power supply to the starting device is continued until it is determined that the engine has been started.

  For example, in the one described in Patent Document 1, a threshold value for engine speed for determining that the engine has been started is set, and the engine starts when the engine speed stably exceeds a predetermined threshold value. The power supply to the device is stopped.

JP 2009-216065 A

  By the way, since the engine repeats the intake-compression-expansion-exhaust stroke in each cylinder, pulsation occurs in the engine rotation speed. For this reason, the threshold value for determining that the start of the engine has been completed is set higher in consideration of the change in the engine speed due to the pulsation of the engine speed. In this case, since the power supply to the starter is stopped after the engine speed reaches the threshold value set higher, the power supply period for supplying power to the starter may be prolonged. In this case, there is a concern that the fuel consumption is reduced or the starter is deteriorated due to an increase in battery power consumption.

  The present invention has been made to solve the above-described problem, and provides an engine stop / start control device capable of shortening the power supply period of the start device and suppressing increase in battery power consumption and deterioration of the start device. There is to do.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  The first invention is applied to a system including an engine (11) and a starter (14) that is driven by power supply from a battery (20) and applies initial rotation to the engine. Combustion determination means for determining the presence or absence of combustion in the combustion chamber (19) based on the amount of change in rotational speed or in-cylinder pressure from the compression top dead center of the engine after the initial rotation is applied by the starter; and the combustion And a power supply control means for stopping the power supply to the starter based on the determination that the determination means determines that the combustion has occurred.

  According to the above configuration, the presence / absence of combustion is determined based on the rotational speed from the compression top dead center or the amount of change in the in-cylinder pressure, and power supply to the starter is stopped based on the determination that combustion has occurred. For this reason, it is possible to grasp the state of combustion in correspondence with the rotational position of the output shaft of the engine and correctly determine whether or not to continue power supply after the combustion. As a result, the power supply period of the starter can be shortened, and an increase in battery power consumption and deterioration of the starter can be suppressed.

  According to a second aspect of the present invention, the combustion determination means determines that the amount of increase in the rotational speed from the compression top dead center has reached a predetermined value, or the amount of increase in the in-cylinder pressure from the compression top dead center is predetermined. It is determined that the combustion has occurred based on reaching the value.

  Based on the fact that the amount of increase in rotational speed from the compression top dead center or the amount of increase in in-cylinder pressure has reached a predetermined value, it is determined that combustion has occurred. In this case, the presence or absence of combustion is determined in the process of increasing the rotational speed or the in-cylinder pressure without waiting for the rotational speed or the in-cylinder pressure to reach the peak value after the compression top dead center. For this reason, the presence or absence of combustion is determined quickly, and power supply to the starter is stopped based on the determination, so that the power supply period of the starter can be shortened suitably.

  According to a third aspect of the present invention, when it is determined that there is the first combustion, the duration of continuing the power supply after the first combustion is based on a parameter that affects the generation of the engine shaft torque. First setting means for variably setting is provided.

  According to the above configuration, even when the engine start is likely to become unstable due to a small engine shaft torque, it is possible to stabilize the engine start and shorten the power supply period of the starter.

  According to a fourth aspect of the present invention, the parameter is a friction parameter that affects the mechanical friction loss of the engine, and the first setting means sets the duration based on the friction parameter.

  According to the above configuration, even when the engine start is likely to become unstable due to a large mechanical friction loss, such as during low temperature start, the power supply period of the starter can be shortened while stabilizing the engine start. Can do.

  In a fifth aspect of the present invention, the parameter is a combustion amount parameter that affects the amount of combustion energy of the engine, and the first setting means sets the duration based on the combustion amount parameter. .

  According to the above configuration, even when the engine start is likely to be unstable due to a small amount of combustion energy, such as when the atmospheric pressure drops, the start-up power supply period can be shortened while stabilizing the engine start. Can be planned.

  According to a sixth aspect of the present invention, when it is determined that the first combustion has occurred, a duration of continuing the power supply after the first combustion is based on a battery voltage of the battery that supplies the power to the starter. And second setting means for variably setting.

  According to the above configuration, the period during which power supply to the starter is continued after the first combustion is set based on the battery voltage that supplies power to the starter. For this reason, even if the engine start is likely to be unstable due to the low battery voltage, the power supply period of the starter can be shortened while stabilizing the engine start.

The schematic block diagram of an engine control system. The timing chart which shows the change of the instantaneous rotational speed immediately after an engine start-up. The flowchart which shows the process which stops the electric power feeding to a starter. The figure which shows the relationship between external temperature and threshold value Th2. The figure which shows the relationship between atmospheric pressure and threshold value Th2. The timing chart which shows the aspect which stops the electric power feeding to a starter. The flowchart which shows the process which stops the electric power feeding to a starter. The figure which shows the relationship between battery voltage and threshold value Th2.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. The present embodiment is embodied in an engine control system mounted on a vehicle. In this control system, an electronic control unit (hereinafter referred to as ECU) is used as a center to control the operating state of the engine. An overall schematic diagram of this system is shown in FIG.

  As shown in FIG. 1, the engine 11 is a spark-ignition gasoline engine, and includes an injector 12 and an ignition device 13 as fuel injection means for each cylinder. Further, a starter 14 is connected to the engine 11 as a starting device that applies initial rotation (cranking rotation) to the crankshaft 16 of the engine 11 when the engine is started. The engine 11 is not limited to a gasoline engine, and may be a diesel engine. The starter 14 may be an ISG (Integrated Starter Generator).

  The starter 14 is connected to the battery 20 via the relay 15. The starter 14 is driven by the power supply from the battery 20 when the ignition switch is turned on. Specifically, when the ignition switch is turned on by the driver's ignition key operation, the relay 15 is closed, power is supplied from the battery 20 to the starter 14, the starter 14 is driven, and the engine 11 is cranked. Give. Instead of the ignition key, a push-type start switch may be provided. Further, in the vehicle in which the idling stop control is performed, when the engine 11 is restarted, the relay 15 is controlled to be closed.

  The ECU 21 is an electronic control device including a microcomputer including a well-known CPU, ROM, RAM, and the like, and controls the fuel injection amount by the injector 12 based on the detection results of various sensors provided in the system. Various engine controls such as ignition control by the ignition device 13 are performed.

  For details on the sensors, the ECU 21 includes an ignition switch, a crank angle sensor 23 for detecting the rotational position (crank angle position) of the crankshaft 16, a pressure in the combustion chamber 19 formed by the cylinder 17 and the piston 18 (in-cylinder An in-cylinder pressure sensor 24 for detecting pressure P), a temperature sensor 25 for detecting outside air temperature, an atmospheric pressure sensor 26 for detecting atmospheric pressure, and a voltage sensor 27 for detecting battery voltage are connected. Signals are sequentially input to the ECU 21.

  The crank angle sensor 23 is an electromagnetic pickup type rotational position detection means that outputs a rectangular detection signal (crank pulse signal) for each predetermined crank angle (for example, at a cycle of 10 ° CA). The rotational speed (instantaneous rotational speed NE) of the engine 11 is calculated from the time required every time the crankshaft 16 rotates by 10 ° CA. Further, according to the detection result of the rotational position, the rotational position of the crankshaft 16 with respect to a predetermined reference position (for example, compression top dead center) is calculated, and the stroke determination of the engine 11 is performed.

  In addition, when starting the engine, the ECU 21 performs control to stop power supply based on the presence or absence of combustion in the combustion chamber 19 of the engine 11 after the start of power supply from the battery 20 to the starter 14. In this case, by controlling the relay 15 to the open state, the power supply from the battery 20 to the starter 14 is stopped, and the cranking of the engine 11 is ended.

  Specifically, as the power supply control to the starter 14, the increase amount ΔNE of the instantaneous rotational speed NE immediately after the piston 18 reaches the compression top dead center after the cranking rotation is applied by the starter 14 is a predetermined value or more. In this case, it is determined that there has been combustion. Further, based on the determination, power supply to the starter 14 is stopped.

  The determination of the presence or absence of combustion in the engine 11 will be described with reference to FIG. FIG. 2 shows a change in the instantaneous rotational speed NE immediately after the start of the engine 11. First, when cranking rotation is applied to the engine 11 by the starter 14, the instantaneous rotational speed NE increases or decreases according to the volume change of the combustion chamber 19 accompanying the reciprocating motion of the piston 18. When the piston 18 reaches the compression top dead center and combustion occurs in the combustion chamber 19 due to the ignition of the ignition device 13, the instantaneous rotational speed NE increases rapidly from the bottom value NEb. After the instantaneous rotational speed NE reaches the peak value NEp, the instantaneous rotational speed NE decreases due to a load acting on the crankshaft or the like. In the case of a four-cylinder engine, combustion is performed every 180 ° CA, and therefore the instantaneous rotational speed NE is repeatedly increased and decreased every 180 ° CA.

  The amount of increase ΔNE from the bottom value NEb to the peak value NEp of the instantaneous rotational speed NE is ΔNE2 when combustion is not occurring, whereas ΔNE1 is larger than ΔNE2 when combustion is occurring. Therefore, it is possible to determine whether or not there is combustion based on the difference in the magnitude of the increase amount ΔNE.

  In this embodiment, as shown in FIG. 2, a threshold value Th1 is provided between ΔNE1 and ΔNE2 in the increase amount ΔNE, and it is determined that combustion has occurred based on the increase amount ΔNE being equal to or greater than the threshold value Th1. Do.

  Hereinafter, the process of stopping power feeding to the starter 14 performed by the ECU 21 will be described with reference to the flowchart of FIG. This process is repeatedly performed by the ECU 21 at a predetermined cycle, and is performed, for example, every time the instantaneous rotational speed NE is calculated at the rising edge of the crank pulse signal.

  First, in step S <b> 11, it is determined whether power is being supplied to the starter 14. If “NO” in the step S11, the present process is terminated as it is, and if “YES” in the step S11, the process proceeds to a step S12.

  In step S12, the current instantaneous rotational speed NE is acquired. In subsequent step S13, it is determined whether or not the piston 18 has reached the compression top dead center. If YES in step S13, the process proceeds to step S14, and the current instantaneous rotational speed NE is acquired as the bottom value NEb. If NO in step S13, the process proceeds to step S15 to determine whether or not the bottom value NEb has been acquired.

  If “NO” in the step S15, the present process is terminated as it is, and if “YES” in the step S15, the process proceeds to a step S16. In step S16, the amount of increase ΔNE from the bottom value NEb to the current instantaneous rotational speed NE is calculated.

  In step S17, it is determined whether or not the increase amount ΔNE is equal to or greater than a threshold value Th1. If NO in step S17, the process is terminated as it is. If YES in step S17, the process proceeds to step S18 assuming that there is combustion. In step S18, the number of combustion times Tc determined to have been combusted after the start of cranking is incremented.

  In the subsequent step S19, the period during which power feeding is continued after the first combustion (power feeding continuation period) is variably set based on parameters that affect the generation of shaft torque of the engine 11. Parameters affecting the generation of shaft torque include a friction parameter affecting the mechanical friction loss of the engine 11 and a combustion amount parameter affecting the amount of combustion energy of the engine 11. In the present embodiment, the threshold Th2 of the number of combustion times Tc is set based on the outside air temperature detected by the temperature sensor 25 as a friction parameter and the atmospheric pressure detected by the atmospheric pressure sensor 26 as a combustion amount parameter. As a result, the power supply duration is set variably.

  Here, the relationship between the outside air temperature and the threshold Th2 and the relationship between the atmospheric pressure and the threshold Th2 will be described with reference to FIGS. FIG. 4 shows the relationship between the outside air temperature and the threshold value Th2. When the outside air temperature is A1 or more, Th2 is 1, and when it is less than A1, Th2 is 2 or more. And This is because the lower the outside air temperature, the larger the mechanical friction loss, and it is considered that the rotation of the engine 11 becomes unstable in the low rotation state after the first combustion.

  FIG. 5 shows the relationship between the atmospheric pressure and the threshold value Th2. When the atmospheric pressure is A2 or more, Th2 is 1, and when it is less than A2, Th2 is 2 or more, and the atmospheric pressure is low. The larger the value. This is because the lower the atmospheric pressure, the lower the intake pressure of the engine 11, so the amount of combustion energy becomes smaller, and it is considered that the rotation of the engine 11 becomes unstable in the low rotation state after the first combustion.

  In step S20, it is determined whether or not the number of combustion times Tc has reached the threshold value Th2. If NO in step S20, the present process is terminated as it is. If YES in step S20, the process proceeds to step S21, power supply to the starter 14 is stopped, and the present process is terminated.

  Next, an aspect of stopping power feeding to the starter 14 will be described with reference to the timing chart of FIG. FIG. 7 shows a timing chart when the threshold Th2 is 1.

  First, when the ignition key is turned on at timing t11, the starter 14 is turned on and the engine 11 starts to rotate. At timing t12, the piston 18 reaches the compression top dead center, and the bottom value NEb of the instantaneous rotational speed NE is acquired. Immediately after the timing t12, when combustion occurs, the instantaneous rotational speed NE increases rapidly from the bottom value NEb. At timing t13, the amount of increase ΔNE from the bottom value NEb reaches the threshold value Th1, and at the same time, power supply to the starter 14 is stopped. Therefore, it is possible to quickly grasp that there has been combustion corresponding to the crank angle position of the engine 11 and to stop power feeding when it has been grasped that there has been combustion. Thereafter, the ignition key is turned off at timing t14.

  As mentioned above, according to this embodiment explained in full detail, the following outstanding effects are acquired.

  According to the above configuration, the presence or absence of combustion is determined based on the change in the instantaneous rotational speed NE from the compression top dead center, and the power supply to the starter 14 is stopped based on the determination that there is combustion. For this reason, it is possible to grasp the state of combustion in correspondence with the crank angle position of the engine 11 and correctly determine whether or not to continue power supply after the combustion. As a result, the power supply period of the starter 14 can be shortened, and an increase in battery power consumption and deterioration of the starter 14 can be suppressed.

  Based on the fact that the rotational speed increase ΔNE from the compression top dead center is greater than or equal to a predetermined value, it is determined that combustion has occurred. In this case, the presence or absence of combustion is determined in the process of increasing the instantaneous rotational speed NE without waiting for the rotational speed to reach the peak value NEp after the compression top dead center. For this reason, the presence or absence of combustion is determined quickly, and power supply to the starter 14 is stopped based on the determination, whereby the power supply period of the starter 14 can be shortened suitably.

  The power supply duration is set based on parameters that affect the generation of the shaft torque of the engine 11. For this reason, even if the engine start is likely to become unstable due to the small shaft torque of the engine 11, the power supply period of the starter 14 can be shortened while stabilizing the engine start.

  Specifically, the power supply continuation period is set based on a friction parameter that affects the mechanical friction loss of the engine 11. For this reason, even when the engine start is likely to become unstable due to a large mechanical friction loss, such as at a low temperature start, the power supply period of the starter 14 can be shortened while stabilizing the engine start.

  In addition, the power supply continuation period is set based on a combustion amount parameter that affects the amount of combustion energy of the engine 11. For this reason, even when the engine start is likely to become unstable due to a small amount of combustion energy, such as when the atmospheric pressure is reduced, the power supply period of the starter 14 can be shortened while stabilizing the engine start. it can.

(Other embodiments)
The above embodiment may be modified as follows, for example.

  A configuration may be adopted in which it is determined that combustion has occurred when the in-cylinder pressure P increases immediately after the piston 18 reaches compression top dead center, and power supply to the starter 14 is stopped based on the determination. Note that it may be determined that combustion has occurred when the pressure increase immediately after the piston 18 reaches compression top dead center is equal to or greater than a predetermined value.

  Processing for stopping power feeding to the starter 14 performed by the ECU 21 will be described with reference to the flowchart of FIG. This process is performed instead of the process of FIG.

  In FIG. 7, in step S31, it is determined whether or not the starter 14 is being fed. In step S32, it is determined whether or not the piston 18 has reached compression top dead center. In step S33, the piston 18 is It is determined whether or not the cylinder pressure P has increased immediately after reaching the compression top dead center. When YES is determined in steps S31 to S33, it is determined that there is combustion, and the process proceeds to step S34.

  In steps S34 to S37, as in steps S18 to S21 of FIG. 3, the number of combustion times Tc is incremented, a threshold value Th2 for the number of combustion times Tc is set, and it is determined that the number of combustion times Tc has reached the threshold value Th2. In addition, power supply to the starter 14 is stopped.

  Also with the above configuration, it is possible to grasp the state of combustion in correspondence with the rotational position of the output shaft of the engine 11 and correctly determine whether or not to continue power supply after the combustion. As a result, the power supply period of the starter 14 can be shortened, and an increase in battery power consumption and deterioration of the starter can be suppressed.

  Based on the fact that the in-cylinder pressure P increased from the compression top dead center, it was determined that there was combustion. In this case, the presence or absence of combustion is determined at the time when the increase of the in-cylinder pressure P is started after the compression top dead center. Also by this, the presence / absence of combustion is quickly determined, and power supply to the starter 14 is stopped based on the determination, so that the power supply period of the starter 14 can be suitably shortened.

  The power supply duration may be variably set based on the battery voltage of the battery 20 that supplies power to the starter 14. In this case, the threshold Th2 is set based on the battery voltage detected by the voltage sensor 27. FIG. 8 shows the relationship between the battery voltage and the threshold value Th2. When the battery voltage is A3 or higher, Th2 is 1, and when the battery voltage is lower than A3, Th2 is 2 or higher, and the lower the voltage is, the lower the voltage is. Use a large value. This is because it is considered that the lower the battery voltage, the lower the driving force of the starter 14 and the unstable engine start.

  According to the above configuration, even when the engine start is likely to be unstable due to a low battery voltage, it is possible to shorten the power supply period of the starter 14 while stabilizing the engine start.

  -It may be determined that the combustion of the engine 11 has occurred based on the temporal change amount of the instantaneous rotational speed NE immediately after the piston 18 reaches the compression top dead center. In this case, it may be determined that the combustion of the engine 11 has occurred when the amount of time change is greater than a predetermined value.

  Although the threshold value Th2 of the number of combustion times Tc determined to have been burned after the start of cranking is variably set, the threshold value Th2 is changed to a constant value (for example, once, twice, three times, etc.) ) May be set.

  -Although it was set as the structure which detects external temperature as a friction parameter which affects a mechanical friction loss, it is good not only as this but the structure which detects the water temperature and oil temperature of the engine 11, for example.

  -Although it was set as the structure which detects atmospheric pressure as a combustion amount parameter which affects the amount of combustion energy, it is good not only as this but the structure which detects the intake pressure of the engine 11, for example.

  DESCRIPTION OF SYMBOLS 11 ... Engine, 14 ... Starter (starter), 19 ... Combustion chamber, 20 ... Battery, 21 ... ECU (Engine stop start control device).

Claims (6)

Applied to a system comprising an engine (11) and a starter (14) driven by power supply from a battery (20) to impart initial rotation to the engine;
Combustion for determining the presence or absence of combustion in the combustion chamber (19) based on the amount of change in rotational speed or in-cylinder pressure from the compression top dead center of the engine after the initial rotation is applied by the starter when starting the engine A determination means;
Power supply control means for stopping the power supply to the starter based on the determination that the combustion has occurred by the combustion determination means;
An engine stop / start control device (21).   The combustion determination means that the amount of increase in the rotational speed from the compression top dead center has reached a predetermined value, or that the amount of increase in the in-cylinder pressure from the compression top dead center has reached a predetermined value. 2. The engine stop / start control device according to claim 1, wherein it is determined that the combustion has occurred.   When it is determined that the first combustion has occurred, a duration for continuing the power supply after the first combustion is variably set based on a parameter that affects the generation of shaft torque of the engine. The engine stop / start control device according to claim 1 or 2, further comprising setting means. The parameter is a friction parameter that affects the mechanical friction loss of the engine,
The engine stop / start control apparatus according to claim 3, wherein the first setting means sets the duration based on the friction parameter. The parameter is a combustion amount parameter that affects the amount of combustion energy of the engine,
The engine stop / start control apparatus according to claim 3 or 4, wherein the first setting means sets the duration based on the combustion amount parameter.   When it is determined that the first combustion has occurred, a duration for continuing the power supply after the first combustion is variably set based on a battery voltage of the battery that supplies the power to the starter. The engine stop / start control apparatus according to any one of claims 1 to 5, further comprising second setting means.

Images