JP4575933B2 - Start control device for internal combustion engine - Google Patents

Description

  The present invention relates to a start control device for an in-vehicle internal combustion engine, and more particularly to a start control device suitable for a vehicle that performs idle stop.

  2. Description of the Related Art Conventionally, there has been known a vehicle in which an idle stop is performed for the purpose of reducing fuel consumption of an internal combustion engine and exhaust gas. In the idle stop, the internal combustion engine is automatically stopped when the vehicle is stopped and the internal combustion engine is in an idling state, and is automatically restarted when the vehicle is started. Various techniques have been proposed for this purpose.

  In the vehicle that performs the idling stop, if it takes time to restart the internal combustion engine, the start operation of the vehicle is delayed with respect to the driver's intention to start, and drivability deteriorates. Therefore, it is important to restart the internal combustion engine quickly and smoothly when performing idle stop.

  However, if restarting is performed by cranking by the starter motor, a large amount of power is consumed at the time of cranking, and the deterioration of the battery is accelerated. May decrease.

  Therefore, at the time of the restart, a rotational torque is applied to the crankshaft from the outside by a starter motor or the like, and fuel is injected into the cylinder in the expansion stroke (in the order of reaching the expansion stroke) to be ignited and burned. To determine whether the internal combustion engine is in a complete explosion state (a state in which the engine can rotate by itself) and keep it in a complete explosion state. When it is determined that there is, a start control device has been proposed in which the power supply to the starter motor or the like is cut off and stopped, thereby shortening the cranking time (assist time) by the starter motor (for example, , See Patent Document 1)

JP 2006-242088 A

  However, in order to reliably start the internal combustion engine, it is necessary to determine whether or not the internal combustion engine is in a complete explosion state based on the worst value (maximum value) of friction in the internal combustion engine. For this reason, for example, when the internal combustion engine is completely warmed up, the maximum friction value is used even though the friction is smaller than when the engine is cold. As a result, the cranking time by the starter motor becomes unnecessarily long. The generation time of undesired operation sounds is prolonged, and problems such as an increase in power consumption occur. On the contrary, if the friction value to be used is smaller than the actual value, a starting failure is caused.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to provide rotational torque to the crankshaft from the outside by a starter motor or the like when starting the internal combustion engine, and to be in the expansion stroke. Cranking time by the starter (in the order in which they are greeted) by injecting fuel into the cylinder, igniting and burning, and rotating the crankshaft using the combustion energy It is an object of the present invention to provide a start control device for an internal combustion engine that can shorten an assist time) to a necessary minimum.

  In order to achieve the above object, one of the start control devices for an internal combustion engine according to the present invention basically ignites and burns fuel by injecting fuel into the cylinder in the order of the expansion stroke in order to start the internal combustion engine. And a first energy supply means for rotating the crankshaft using the combustion energy, and a second energy supply means for applying a rotational torque to the crankshaft from the outside. And a state of motion detecting means for detecting a state of motion such as a rotational speed in the internal combustion engine, and based on the state of motion, the internal combustion engine is brought into a complete explosion state in which a required rotational state is maintained after the start of motion. The complete explosion determination means for determining whether or not there is, and the first energy supply means and the second energy supply means are controlled based on the movement state, and the complete explosion determination means is in the complete explosion state. When it is determined that that comprises and a starting operation control means for stopping the operation of the second energy supply unit.

  And a friction detection means for detecting or estimating the magnitude of the friction of the internal combustion engine, wherein the complete explosion determination means performs the complete explosion determination in consideration of the influence of the friction of the internal combustion engine in addition to the motion state. It is characterized by doing.

  One of the other aspects of the start control device for an internal combustion engine according to the present invention is basically that when starting, fuel is injected into the cylinder in the order of the expansion stroke and ignited and burned, and the energy of the combustion is reduced. A start control device for an internal combustion engine that rotates a crankshaft by using an external drive means such as a starter motor and applies a rotational torque to the crankshaft from the outside. A complete explosion determination means for determining whether or not a complete explosion state is maintained, a friction detection means for detecting or estimating the magnitude of the friction of the internal combustion engine, and the complete explosion determination means. A starting operation control means for stopping the application of rotational torque to the crankshaft by the external drive means when it is determined that the explosion state is present, and the complete explosion determination means comprises the motion state In addition, it is characterized in that to perform the complete combustion determination in consideration of the influence of the friction of the internal combustion engine.

  The complete explosion determination means preferably changes the timing for performing the complete explosion determination based on the magnitude of friction of the internal combustion engine.

  Preferably, the complete explosion determination means sets the complete explosion determination timing by a rotation angle from the ignition timing of the preceding combustion cylinder.

  Preferably, the friction detection means estimates the magnitude of the friction of the internal combustion engine based on the cooling water temperature of the internal combustion engine.

  Preferably, the friction detection means estimates the magnitude of the friction of the internal combustion engine based on the operating time of the internal combustion engine.

  The complete explosion determination means is preferably configured to retard the complete explosion determination timing as the friction of the internal combustion engine increases.

  The complete explosion determination timing performed by the complete explosion determination means is preferably such that the rotation angle from the ignition timing of the preceding combustion cylinder is the rotation from the ignition timing of the preceding combustion cylinder to the ignition timing of the cylinder in which combustion is performed next. It is set at a time exceeding 1/2 of the angle.

  Preferably, the complete explosion determination means determines whether or not the complete explosion state is in effect based on the amount of change in engine speed and the required time from the ignition timing of the preceding combustion cylinder to the complete explosion determination timing. To be done.

  In the internal combustion engine start control device according to the present invention, at the time of start-up, a rotational torque is applied to the crankshaft from the outside by a starter motor or the like, and fuel is injected into the cylinders in the expansion stroke (in order of reaching the expansion stroke). After the ignition combustion is performed and the crankshaft is rotated using the combustion energy, the complete explosion determination is performed in consideration of the influence of the friction of the internal combustion engine. More preferably, for example, the timing for performing the complete explosion determination is changed based on the size of the friction, so that the completion can be completed more accurately as compared with the conventional one using the maximum value of friction. Explosive judgment can be made. As a result, the frequency of start-up failures is reduced and the starter cranking time (assist time) can be reduced to the minimum necessary. As a result, the power consumption can be reduced and the battery life can be extended. In addition, the generation time of undesired operation sounds accompanying cranking can be shortened, and the commercial value can be increased.

  Further, since the magnitude of the friction of the internal combustion engine is estimated based on the engine coolant temperature and the operating time, it is possible to obtain the above-mentioned effects without adding a sensor and incurring a significant cost increase. Can do.

  Further, the complete explosion determination timing is determined when the rotation angle from the ignition timing of the preceding combustion cylinder exceeds 1/2 of the rotation angle from the ignition timing of the preceding combustion cylinder to the ignition timing of the cylinder where combustion is performed next, For example, in the case of an in-line 4-cylinder internal combustion engine (in which each stroke of intake → compression → expansion → exhaust is shifted by 180 deg), the rotation angle from the ignition timing of the preceding combustion cylinder is, for example, 135 deg (this The angle at which the correction according to the magnitude of friction is added) is reached, and an area where the engine speed at which the influence of the friction appears is reduced is added to the complete explosion determination. As a result, the complete explosion determination can be performed more accurately.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments (examples) of an internal combustion engine start control device of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment (first example) of a start control device for an internal combustion engine according to the present invention and an example of an internal combustion engine to which it is applied.

  In FIG. 1, the internal combustion engine 1 is configured as, for example, a four-cycle in-line four-cylinder engine mounted on an automobile (in FIG. 1, only one cylinder 2 is shown, but the other cylinders have the same configuration). is there).

  An internal combustion engine 1 directly injects fuel from a fuel injection valve 3 into a combustion chamber 4 in a cylinder 2 and ignites (ignites) a mixture of the injected fuel and air in the combustion chamber with an ignition plug 5. It is an injection internal combustion engine. Gasoline is preferably used as the fuel injected from the fuel injection valve 3, but other fuels may be used. Further, the internal combustion engine 1 is provided with an intake valve 8 and an exhaust valve 9 that open and close between the combustion chamber 4 and the intake passage 6 and the exhaust passage 7, respectively.

  In addition, in order to start the internal combustion engine 1, the cylinder 2 is injected with fuel in the cylinder 2 in the order of the expansion stroke, ignited and burned, and the crankshaft 13 is rotated using the combustion energy. A first energy supply means including a fuel injection valve 5, a piston 19, a connecting rod 18 and the like is provided, and a rotational torque is applied to the crankshaft 13 from the outside in order to start the internal combustion engine 1. A second energy supply unit including a starter motor 11, a gear mechanism 12, a battery (not shown), and the like is attached.

  The (first) energy supply means by the combustion is also realized by control performed on each cylinder 2 of the internal combustion engine 1 from a state in which a control unit 10 described later is stopped.

  The starter motor 11 can change the kinetic energy applied to the internal combustion engine 1 by controlling the supply current or supply voltage, or does not perform current / voltage control as is generally used. Some control the supplied energy only on and off.

  The control unit 10 incorporates a microcomputer comprising a microprocessor, RAM, ROM, IO, etc., and controls the internal combustion engine 1 according to a program recorded in the ROM, for example, start control described later, an empty space provided in the exhaust passage 7. Fuel injection control such as controlling the fuel injection amount by the fuel injection valve 3 so that the air-fuel ratio becomes a predetermined air-fuel ratio based on the signal obtained from the fuel ratio sensor, and the ignition timing by the spark plug 5 according to the engine operating state Control and so on.

  The control unit 10 includes a signal corresponding to the crank angle of the crankshaft 13 from the crank angle sensor 14, a signal corresponding to the coolant temperature of the internal combustion engine 1 from the water temperature sensor 15, and an accelerator operation from an accelerator sensor (not shown). In response to the signal, a signal is supplied by depressing the foot brake from the brake switch 16. Further, the vehicle is connected to a control unit 17 for controlling the brake system by communication to obtain speed information of the automobile.

  Next, an example of control that the control unit 10 executes at the start will be described with reference to the functional block diagram of FIG. The control unit 10 receives input signals from the sensors for detecting a state necessary for starting / stopping / operating the internal combustion engine 1 into the control unit, and for starting / stopping / operating the internal combustion engine 1. The internal combustion engine 1 and the fuel injection valve 3, the spark plug 5, and the input / output means 20 for performing output processing for controlling the drive of the throttle valve (not shown) for controlling the air flow rate are normally used. In addition to control means for starting and operating, it has start control means 21, stop control means 22, and operation control means 23.

  The start control means 21 is a control means for starting the internal combustion engine 1, the stop control means 22 is a control means for stopping the internal combustion engine 1, and the operation control means 23 is a brake switch 16 or the like. This is a means for controlling the start or stop command of the internal combustion engine 1 by the operation.

  In the present embodiment, the start control means 21 includes a complete explosion determination means 26 for determining whether or not the rotation state of the internal combustion engine 1 is maintained, and the first and second energy supply means (component members) described above. Energy supply control means 25 for performing control.

  The energy supply control means 25 has a start-up combustion control means 27 for controlling the first energy supply means and a starter control means 28 for controlling the second energy supply means. , The start-up combustion control means 27 and the starter control means 28 are actuated and operated based on the motion state information of the internal combustion engine 1 from the complete explosion determination means 26 (information on whether or not the engine is in a complete explosion state). Send a stop command.

  Based on this command, the combustion control means 27 determines the amount of fuel injected from the fuel injection valve 3 and the injection timing, the timing of ignition by the spark plug 5, the timing and amount of the intake valve 8 and the exhaust valve 9, and the throttle valve (not shown). Combustion control optimal for the internal combustion engine 1 is realized in order to set the opening and the like and to start the internal combustion engine 1 quickly and smoothly.

  Further, the starter control means 28 drives the starter motor 11 to assist the start of the internal combustion engine 1 based on the command.

  In particular, by appropriately supplying and stopping the energy supply means according to the motion state of the internal combustion engine 1, a stable start can be achieved without causing a start failure and without excessive energy supply. Realize.

Next, a control flow in the start control of the present embodiment will be described.
Before explaining the details of the control flow of the start control, a general flow of stop control performed after the start and subsequent start control will be described with reference to FIG.

  The stop control flow and the start control flow are executed by the start control means 21 and the stop control means 22 of the control unit 10. Further, in the control unit 10, the operation control means 23 for controlling the start or stop command of the internal combustion engine 1 operates in a processing flow different from this processing, and stop control is performed based on the stop request or the start request. A flow and a start control flow are executed.

  Here, the stop condition is, for example, when the internal combustion engine 1 is in a warm-up state, a brake operation state, and an idling state where the accelerator is not stepped on, and the start condition is an operation related to the start of the vehicle from the idling state. For example, it is assumed that there is a brake release, an accelerator pedal depression operation, a shift operation, or the like. As described above, the stop control and the start control in FIG. 3 realize an idling stop in which the internal combustion engine 1 is stopped when the vehicle is stopped and the internal combustion engine 1 is restarted before starting.

  In FIG. 3, after the internal combustion engine 1 is started (S101), the control unit 10 determines the presence or absence of an automatic stop request for the internal combustion engine 1 by the operation control means 23 according to the operating state of the internal combustion engine 1 (S102). If there is no request for automatic stop (No in S103), the normal operation control of the internal combustion engine is continued (S104), and it is determined again whether or not there is a request for automatic stop of the internal combustion engine (S102). If there is a request for automatic stop (Yes in S103), internal combustion engine stop control (S105) is executed.

  Next, a request for restart is waited while the internal combustion engine is stopped (S106). Here, it is determined whether or not there is a request for starting the internal combustion engine 1 (S107). If there is a start request, start control of the internal combustion engine 1 is started (S108). When there is no start request, the internal combustion engine 1 remains in a stopped state and waits for the start request.

  Next, a start control flow when there is an internal combustion engine automatic start request will be described with reference to FIG.

  When the internal combustion engine 1 is stopped (S106), it is determined whether or not there is an internal combustion engine automatic start request (S107). If there is an automatic start request, energy supply to the internal combustion engine 1 by the first energy supply means ( Combustion control) and energy supply (rotation torque application) to the internal combustion engine 1 by the second energy supply means (starter motor 11) are started, and start is started (S201). The first energy supply control (combustion control) and the second energy supply control (starter motor control) are performed as independent control flows, but the timing for starting the energy supply to the internal combustion engine 1 starts simultaneously. In some cases, cooperative control such as sequential start is performed. For example, in the first energy supply control (combustion control), fuel is injected into each cylinder 2 of the internal combustion engine 1 and ignited to generate combustion. In the second energy supply control (starter motor control), Then, rotational torque is applied to the crankshaft 13 of the internal combustion engine 1 by the starter motor 11. The first energy supply control (combustion control) is performed first, and then the second energy supply control (starter motor control) is performed after a predetermined time has elapsed. Alternatively, the first energy supply control (combustion control) and the second energy supply control (starter motor control) may be performed at the same time, and the starting energy may be supplied to the internal combustion engine 1 simultaneously.

  As described above, when there is a start request, supply of kinetic energy to the internal combustion engine 1 is started by the first and second energy supply means. When the first energy supply control (combustion control) and the second energy supply control (starter motor control) are performed, the internal combustion engine 1 starts to move (rotate). In order to quantitatively evaluate the motion state, the state of the internal combustion engine 1 is calculated quantitatively from the amount of change in the rotational speed of the internal combustion engine 1, thereby evaluating the sustainability of the rotation of the internal combustion engine 1 and determining a complete explosion (210).

  Here, the conventional start control characteristics will be described with reference to FIG. 5. When the internal combustion engine 1 is started (S202), the rotation angle of the internal combustion engine 1 is 90 deg after the rotation start time (= start start time: 0 deg). Until the point A is reached (S205), combustion control at start-up and rotation assist by the starter motor 11 are performed (S204). When the rotation angle of the internal combustion engine 1 reaches point A (S205), ignition by the spark plug 5 is performed, and the rotational speed Ne1 of the internal combustion engine 1 and the elapsed time T1 from the rotation start time (0 deg) are measured and stored. (S206). Further, a rotation angle C that is a timing for determining complete explosion is calculated (S207).

  The solid line in FIG. 5 shows the relationship between the rotation angle and the engine speed when the four-cylinder internal combustion engine is started. Here, at the point B (180 deg) 90 deg after the point A (90 deg), the complete explosion state (based on the amount of increase in the rotational speed Ne1 and the rotational speed Ne2 of the point B is based on the rotational speed increase amount ( It is determined whether or not it is in a state where it can rotate by itself. That is, when the rotation speed increase amount exceeds the set value, it is determined that a complete explosion has occurred, and the rotation assist by the starter motor 11 indicated by the broken line is turned off. In the case of this conventional example, the decrease in the rotational speed from the point B where the next cylinder becomes the compression stroke to the ignition timing (270 deg) of the next cylinder becomes large, and the engine may fail to start and stall.

  Therefore, in this embodiment, as shown in FIG. 6, the complete explosion determination timing is set so that the rotation angle from point A (90 deg), which is the ignition timing of the preceding combustion cylinder, so that the friction in the compression stroke can also be evaluated. A time exceeding 1/2 (90 deg) of the rotation angle (180 deg) from the point A to the ignition timing (270 deg) of the cylinder in which combustion is performed next (for example, a time rotated 135 deg from the point A = a rotation start time (0 deg) ) To the time (point C in FIG. 6).

  Further, since the friction increases as the internal combustion engine 1 cools, as shown in FIG. 7, as the cooling water temperature decreases, A can be reliably started even when the assist time by the starter motor 11 becomes longer. Increase the rotation angle from point C to point C (greater than 135 deg). In other words, the point C, which is the complete explosion determination timing, is delayed more greatly as the cooling water temperature is lower.

  Returning to FIG. 4, when the rotation angle reaches the point C (= A + C), the rotational speed Ne2 of the internal combustion engine 1 and the elapsed time T2 from the rotation start time (0 deg) are measured and stored (S209). Here, if the amount of increase in the number of revolutions per unit time from point A to point C does not exceed the predetermined value α (S210), the complete explosion state is not recognized, so point A is the ignition timing (270 deg) of the next cylinder. To determine whether or not the next combustion is complete. If the amount of increase in the rotational speed exceeds the predetermined value α, it is recognized that a complete explosion has occurred, so start assist by the starter motor 11 is stopped (S212).

  As described above, in the start control device for an internal combustion engine according to the present embodiment, when starting, the starter motor 11 applies rotational torque to the crankshaft 13 from the outside and is in the expansion stroke (in order of reaching the expansion stroke). The fuel is injected into the cylinder and ignited and burned, and the crankshaft 13 is rotated using the combustion energy, and the complete explosion determination is made in consideration of the influence of the friction of the internal combustion engine. The More specifically, since the timing for performing the complete explosion determination is changed based on the size of the friction, it is more accurately completed compared to the conventional one using the maximum value of friction. Explosive judgment can be made. Therefore, the frequency of start-up failures is reduced, and the cranking time (assist time) by the starter can be reduced to the minimum necessary. As a result, the power consumption can be reduced and the battery life can be extended. In addition, the generation time of undesired operation sounds accompanying cranking can be shortened, and the commercial value can be increased.

  In addition, since the magnitude of the friction of the internal combustion engine is estimated based on the engine coolant temperature, it is possible to obtain the above-described effects without adding a sensor and incurring a significant cost increase. In the above-described embodiment, the friction of the internal combustion engine 1 is replaced with the cooling water temperature (estimated based on the cooling water temperature), but is increased in the operating state (S102) of the internal combustion engine, and the internal combustion engine is stopped ( It is also possible to replace with the operation time decreased in S106) (friction can be estimated based on the operation time).

  Further, the complete explosion determination timing is determined when the rotation angle from the ignition timing of the preceding combustion cylinder exceeds 1/2 of the rotation angle from the ignition timing of the preceding combustion cylinder to the ignition timing of the cylinder where combustion is performed next, For example, in the case of an in-line 4-cylinder internal combustion engine (in which each stroke of intake → compression → expansion → exhaust is shifted by 180 deg), the rotation angle from the ignition timing of the preceding combustion cylinder is, for example, 135 deg (this The angle at which the correction according to the magnitude of friction is added) is reached, and an area where the engine speed at which the influence of the friction appears is reduced is added to the complete explosion determination. As a result, the complete explosion determination can be performed more accurately.

  Further, the present invention is not limited to the restart at the time of idling stop, but can also be applied at the start corresponding to the ON operation of the ignition key, for example.

  In addition, the present invention can be applied to all cases where the internal combustion engine is started, such as when the internal combustion engine is restarted in a hybrid vehicle using both the internal combustion engine and the electric motor.

  Further, in the above embodiment, whether or not a complete explosion has occurred is determined based on the amount of change in the engine speed and the required time (the amount of increase in the number of revolutions per unit time) from the ignition timing of the preceding combustion cylinder to the complete explosion determination timing. However, instead of this, for example, the complete explosion determination may be performed based on the acceleration obtained from the difference in time required for 10 deg rotation at the point A and the point C.

1 is a schematic configuration diagram showing an embodiment of a start control device according to the present invention and an example of an internal combustion engine to which the start control device is applied. The functional block diagram which shows the outline | summary of the control unit which comprises the principal part of the starting control apparatus shown by FIG. 3 is a flowchart showing an example of engine stop control and start control by the control unit shown in FIG. 2. The flowchart which shows an example of starting control by the control unit shown by FIG. The figure used for description of the outline | summary of the start control in the conventional start control apparatus. The figure which is provided for description of the outline | summary of the start control in the start control apparatus based on this invention. The graph with which it uses for description of the complete explosion determination in the starting control apparatus which concerns on this invention.

Explanation of symbols

1 Internal combustion engine (inline 4-cylinder engine)
2 cylinder 3 fuel injection valve 4 combustion chamber 5 spark plug 6 intake passage 7 exhaust passage 8 intake valve 9 exhaust valve 10 control unit 11 starter motor 12 gear mechanism 13 crankshaft 14 crank angle sensor 15 water temperature sensor 16 brake switch 17 brake control Unit 20 Input / output means 21 Start control means 22 Stop control means 23 Operation control means 25 Energy supply control means 26 Complete explosion determination means 27 Start-up combustion control means 28 Starter control means

Claims (7)

In order to start the internal combustion engine, first energy supply means for injecting fuel into the cylinders in the order of reaching the expansion stroke, causing ignition combustion, and rotating the crankshaft using the energy of the combustion, and the crankshaft A start control device for an internal combustion engine, comprising: a second energy supply means for applying rotational torque from the outside;
The start control device includes a motion state detection means for detecting a motion state such as a rotation speed in the internal combustion engine;
A complete explosion determination means for determining whether or not the internal combustion engine is in a complete explosion state in which a required rotational state is maintained after the start of motion based on the motion state;
When the operation control of the first energy supply means and the second energy supply means is performed based on the motion state, and the complete explosion determination means determines that the complete explosion state is present, the second energy supply is performed. A starting operation control means for stopping the operation of the supply means, and a friction detection means for detecting or estimating the magnitude of the friction of the internal combustion engine,
The start control device for an internal combustion engine, wherein the complete explosion determination means changes a timing for performing the complete explosion determination based on a magnitude of friction of the internal combustion engine in addition to the motion state. 2. The start control device for an internal combustion engine according to claim 1 , wherein the complete explosion determination means sets the complete explosion determination timing based on a rotation angle from an ignition timing of a preceding combustion cylinder. The start control device for an internal combustion engine according to claim 1 or 2 , wherein the friction detection means estimates the magnitude of the friction of the internal combustion engine based on a cooling water temperature of the internal combustion engine. The start control device for an internal combustion engine according to claim 1 or 2 , wherein the friction detection means estimates the magnitude of the friction of the internal combustion engine based on an operation time of the internal combustion engine. The start control device for an internal combustion engine according to any one of claims 1 to 4 , wherein the complete explosion determination means delays the complete explosion determination timing as the friction of the internal combustion engine increases. The complete explosion determination timing performed by the complete explosion determination means is the rotation angle from the ignition timing of the preceding combustion cylinder being one of the rotation angles from the ignition timing of the preceding combustion cylinder to the ignition timing of the cylinder in which combustion is performed next. The start control device for an internal combustion engine according to any one of claims 1 to 5 , wherein the start time is set at a time exceeding / 2. The complete explosion determination means determines whether or not the complete explosion state is in effect based on the amount of change in engine speed and the required time from the ignition timing of the preceding combustion cylinder to the complete explosion determination timing. The start control device for an internal combustion engine according to any one of claims 1 to 6 , wherein the start control device is an internal combustion engine.

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