JP2016023559A - Engine start control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve restart of an engine while suppressing development man-hours and not increasing a data volume stored in an ECU.SOLUTION: An engine start control device (3) stops an engine (1) when a throttle valve is closed, and starts the engine when the throttle valve is opened after the engine is stopped. The engine start control device comprises a crank angle sensor (32) detecting an engine rotation speed, and an ECU (2) which drives the engine in the normal rotation when the engine rotation speed at a predetermined crank position at the time of opening the throttle valve is equal to or higher than NE2, and drives the engine in the normal rotation after driving the engine in the reverse rotation to a preparation position for engine start when the engine rotation speed is lower than NE2.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an engine start control device for a motorcycle, and more particularly to an engine start control device for restarting an engine after idling stop.

  Conventionally, an engine of a vehicle is provided with an idling stop function that temporarily stops the engine during parking or waiting for a signal or the like to improve fuel consumption or reduce exhaust gas. A vehicle having an idling stop function includes an engine start control device that detects that the throttle valve is closed and stops the engine, detects that the throttle valve is opened, and restarts the engine. (For example, refer to Patent Document 1).

  The engine start control device described in Patent Literature 1 determines whether the engine rotation speed when the throttle valve (throttle) is opened is a rotation speed suitable for restarting the engine. For example, when the engine rotation speed is higher than a predetermined rotation speed, the engine is rotated forward and restarted. On the other hand, when the engine rotation speed is lower than the predetermined rotation speed, the engine is completely stopped, and then the crankshaft is positioned to a predetermined position and then rotated forward to restart the engine.

Japanese Patent No. 4082578

  By the way, the predetermined rotational speed of the engine, which is the reference for the above judgment, needs to be determined corresponding to every position of the crank position. Since this predetermined rotational speed is obtained by experiments, there is a problem that the development man-hour increases. Further, since a predetermined rotational speed corresponding to each crank position must be stored as map data in an ECU (Electronic Control Unit), there is a problem that the map data becomes enormous.

  The present invention has been made in view of the above point, and is an engine start control device capable of realizing engine restart without reducing the development man-hours and without increasing the amount of map data stored in the ECU. The purpose is to provide.

  An engine start control device according to the present invention is an engine start control device that stops an engine when a throttle valve is closed, and starts the engine when the throttle valve is opened after the engine is stopped. A detecting means for detecting speed, and when the engine rotational speed at a predetermined crank position is equal to or higher than a threshold value after opening the throttle valve, the engine is driven to rotate forward, while the engine rotational speed is lower than the threshold value. Control means for driving the engine in the normal direction after the engine is driven in the reverse direction.

  According to this configuration, when restarting after the engine is stopped, the determination of the engine driving method (forward rotation driving or reverse rotation driving) can be performed only by the engine rotation speed at the predetermined crank position. In this case, only the engine speed at a predetermined (single) crank position needs to be investigated in setting a threshold value as a determination criterion. Therefore, the man-hour for determining the threshold can be reduced. Therefore, for example, when a similar engine start control device is applied to an engine of another model, the development man-hour can be reduced. In addition, since the above determination is performed at a predetermined crank position, a threshold value serving as a determination criterion can be configured with a single data. For this reason, compared with the map data comprised by the threshold value (predetermined rotational speed) corresponding to all the crank positions like before, the data amount stored in ECU can be reduced.

  In the engine start control device of the present invention, it is preferable that the control means drives the engine in the forward direction to the predetermined crank position after opening the throttle valve. In this case, as a result of forcibly driving the engine to the predetermined crank position, it is possible to determine the engine driving method when the engine is restarted at the predetermined crank position.

  Further, in the engine start control device according to the present invention, the control means, after the engine rotational speed is below a threshold value in the process of forwardly driving the engine to the predetermined crank position, after reversely driving the engine It is preferable to drive the engine forward. In this case, even if the engine does not normally rotate to the predetermined crank position, the engine is forcibly driven in reverse. For this reason, even if the engine speed sufficient for restarting the engine is not obtained, the engine can be reliably restarted.

  Further, in the engine start control device of the present invention, it is preferable that the threshold value is increased as the throttle opening increases in accordance with the throttle opening. In this case, the engine driving method can be more accurately determined according to the change in the throttle opening.

  In the engine start control device of the present invention, it is preferable that the threshold value is increased as the intake air temperature decreases in accordance with the intake air temperature. In this case, the engine driving method can be more accurately determined according to the change in the intake air temperature.

  Further, in the engine start control device of the present invention, it is preferable that the threshold value is increased as the engine water temperature decreases according to the engine water temperature. In this case, the engine driving method can be more accurately determined according to the change in the engine water temperature.

  In the engine start control device of the present invention, it is preferable that the control means performs brake control of the engine before driving the engine in reverse. In this case, the time until the engine rotation is stopped can be shortened, and the responsiveness of engine restart can be improved.

  In the engine start control device of the present invention, it is preferable that the control means performs reverse rotation control at a timing at which the rotation of the engine stops due to cylinder internal pressure when the engine is driven in reverse rotation. In this case, the driving load of the engine can be reduced, and current consumption can be reduced.

  Further, in the engine start control device of the present invention, it is preferable that the control means executes the driving of the engine by a starter generator. In this case, power generation and engine drive can be realized by a single mechanism, and the configuration is simplified.

  In the engine start control device of the present invention, it is preferable that the control means determines an engine rotation speed at a crank position in a compression stroke as the predetermined crank position. Since the driving resistance of the engine is high in the compression stroke, it is possible to easily predict the criterion (threshold value) for determining whether to drive the engine forward or backward. As a result, the determination accuracy of the engine driving method can be improved.

  According to the engine start control device of the present invention, the engine driving method is determined from the engine rotational speed at a predetermined crank position, thereby reducing development man-hours and without increasing the amount of map data stored in the ECU. The engine can be restarted.

It is a schematic diagram of the engine which concerns on this Embodiment. It is a graph which shows the cylinder internal pressure with respect to the crank position of the engine which concerns on this Embodiment. It is a graph which shows the change of the engine speed at the time of idling stop of the engine which concerns on this Embodiment, or restarting. It is a functional block diagram of an engine start control device according to the present embodiment. It is a graph which shows the cylinder internal pressure with respect to the crank position in FIG. 3B or FIG. 3C of the engine which concerns on this Embodiment. It is a flowchart which shows an example of the restart control of the engine which concerns on this Embodiment.

  Hereinafter, an engine start control device according to the present embodiment will be described with reference to the accompanying drawings. Note that the engine start control device according to the present embodiment is not limited to the configuration shown below, and can be changed as appropriate. The engine start control device may be applied to any vehicle, and can be applied to, for example, a motorcycle, a buggy type automatic tricycle, or an automatic four-wheel vehicle.

  First, a general schematic configuration of the engine will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram of an engine according to the present embodiment. FIG. 2 is a graph showing the in-cylinder pressure with respect to the crank position of the engine according to the present embodiment. As shown in FIG. 1, the engine 1 is, for example, a direct-acting DOHC (Double OverHead Camshaft) engine, and includes a crankshaft 10, a cylinder 11, a cylinder head 12, and the like in a crankcase (not shown). The A piston 13 is accommodated in the cylinder 11 so as to reciprocate up and down. The crankshaft 10 and the piston 13 are connected by a connecting rod 14, and the crankshaft 10 is rotated via the connecting rod 14 as the piston 13 reciprocates in the vertical direction.

  The internal space of the cylinder head 12 constitutes a combustion chamber 15. The cylinder head 12 is provided with an intake valve 16 and an exhaust valve 17 corresponding to the intake port and the exhaust port. A pair of camshafts 18 are provided corresponding to the intake valve 16 and the exhaust valve 17. A cam chain (not shown) is spanned between the crankshaft 10 and the pair of camshafts 18, and the rotation of the crankshaft 10 is transmitted to the pair of camshafts 18 via the cam chains.

  By rotating the pair of camshafts 18, the intake valve 16 and the exhaust valve 17 are reciprocated toward the combustion chamber 15. In this way, the opening / closing timing of each of the intake valve 16 and the exhaust valve 17 is adjusted. An ignition device 19 that ignites the air-fuel mixture in the combustion chamber 15 is provided above the combustion chamber 15. The ignition device 19 ignites at a predetermined timing based on the ignition signal output from the ECU 2.

  The crankshaft 10 is connected to a starter generator 20 provided on the same axis as the crankshaft 10. The starter generator 20 is connected to a battery (not shown) via an inverter (controller) (not shown), and starts the engine 1 upon receiving power supply from the battery. In addition, the starter generator 20 recovers electrical energy from the rotational energy while the engine 1 is being driven. As described above, the starter generator 20 has both a function as a starter motor that starts the engine 1 and a function as a generator that generates electric power by driving the engine 1.

  As will be described in detail later, the starter generator 20 can rotate the crankshaft 10 forward or backward when the engine 1 is started. When the crankshaft 10 is reversely rotated, the rotation load of the crankshaft 10 is increased by switching to the brake control, and the brake can be applied to the crankshaft 10 during normal rotation.

  Various operations in the engine 1 are controlled by the ECU 2. The ECU 2 includes a processor that executes various processes in the engine 1, a memory, and the like. The memory is configured by a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory) according to the application. The memory stores a control program for controlling each part of the engine 1. The ECU 2 determines the state of the vehicle from various sensors provided in the vehicle, and performs control such as ignition timing of the ignition device 19, idling stop of the engine 1, and restart of the engine 1 after idling stop.

  For example, in the case of idling stop control, the ECU 2 determines the state of the vehicle from the vehicle speed and the throttle operation amount. Then, when there is no operation of the throttle (not shown) and the throttle valve (not shown) is closed, the ECU 2 stops fuel injection and ignition control. In the case of change-of-mind control described later, the ECU 2 determines the state of the engine 1 from the throttle operation amount and the rotational speed of the crankshaft 10. When the throttle is operated and the throttle valve is opened, the ECU 2 drives the starter generator 20 to start the engine 1.

  In general, the engine 1 configured as described above operates in four strokes. First, when the piston 13 descends, the intake valve 16 is opened, and the air-fuel mixture is sent to the combustion chamber 15 through the intake port (intake stroke). Thereafter, the intake valve 16 is closed, and the piston 13 is raised to compress the air-fuel mixture (compression stroke). When the piston 13 reaches near the top dead center, the compressed air-fuel mixture explodes (explosion stroke) by being ignited at a predetermined timing by the ignition device 19. When the pressure in the combustion chamber increases due to the explosion of the air-fuel mixture, the piston 13 descends. The downward movement of the piston 13 is transmitted to the crankshaft 10 via the connecting rod 14, and the crankshaft 10 rotates. Thereafter, when the piston 13 descends to the bottom dead center and starts to rise again due to inertia, the exhaust valve 17 is opened and the combustion gas is discharged from the exhaust port (exhaust stroke). By repeating these strokes, the rotation of the engine 1 is maintained.

  Further, in each stroke of the engine 1, the pressure in the cylinder 11 changes as shown in the graph shown in FIG. In the graph shown in FIG. 2, the pressure in the cylinder 11 shows a constant value in the exhaust and intake strokes, and is rapidly increased in the compression stroke. Then, when the mixed gas in the combustion chamber 15 explodes near the compression top dead center and shifts to the explosion stroke, the pressure is reduced at once.

  Next, idling stop control and change of mind control will be described with reference to FIG. FIG. 3 is a graph showing changes in engine rotation speed at the time of idling stop or restart of the engine according to the present embodiment. First, the idling stop control will be described. As shown in FIG. 3A, when the engine rotation speed is constant and the idling stop condition is satisfied, the ECU 2 (see FIG. 1) controls to decrease the engine rotation speed.

  Specifically, fuel injection and ignition control are stopped. When the engine speed N gradually decreases to zero, the crankshaft 10 (see FIG. 1) is driven in reverse or forward to finely adjust the crank position. Thereby, the crankshaft 10 is positioned at an optimum position for restarting the engine 1 (see FIG. 1). As a result, the engine 1 can be easily restarted. The conditions for establishing the idling stop are set by, for example, the vehicle speed, the throttle opening degree, and the like.

  Next, change of mind control will be described. Here, the change of mind control is, for example, when the front signal is red and the vehicle decelerates or stops, when the signal changes to blue and the occupant opens the throttle to drive again, that is, It shows the engine control when the occupant's operation changes due to change of mind. The change-of-mind control is divided into the following two patterns shown in FIG. 3B or FIG. 3C depending on the timing of change of mind, that is, the engine speed N when the throttle valve is opened.

  As shown in FIG. 3B, after the engine speed N has settled down, the idling stop condition is satisfied, and the fuel injection and ignition control are stopped. As a result, the engine 1 (see FIG. 1) rotates by inertia and the engine rotation speed N gradually decreases. Then, after the throttle valve is opened, when the engine rotational speed N is higher than the predetermined rotational speed NE2 (threshold), the ECU 2 controls the engine 1 to rotate forward to increase the rotational speed. As a result, the engine rotational speed N recovers until the start of idling stop, fuel injection and ignition control are resumed, and when the predetermined rotational speed NE1 (threshold) is exceeded, the engine 1 is restarted. Here, the predetermined rotational speed NE2 (hereinafter simply referred to as NE2) indicates a normal rotation continuation determination rotational speed that is a criterion for determining whether to drive the engine forward or reversely. NE1) indicates a start completion determination rotational speed for determining whether or not the engine 1 has been started.

  Similarly in FIG. 3C, after the engine speed N has settled down, the idling stop condition is satisfied, and the fuel injection and ignition control are stopped. After the engine speed N is gradually reduced and the throttle valve is opened, when the engine speed N is smaller than NE2, the ECU 2 controls the starter generator 20 to brake and reduce the engine speed N. When the engine rotational speed N falls below the predetermined rotational speed NE3 (threshold value), the ECU 2 reverses the crankshaft 10 and positions the crankshaft 10 to a predetermined position, and increases the engine rotational speed N by rotating the crankshaft 10 forward again. To control. As a result, the engine speed N recovers before the start of the idling stop, and when the engine speed N exceeds the predetermined speed NE1, the engine 1 is restarted. Here, the predetermined rotational speed NE3 (hereinafter simply referred to as NE3) indicates an engine stop determination rotational speed for determining whether or not the engine 1 has stopped.

  As shown in FIG. 3B and FIG. 3C, the ECU 2 determines whether the engine speed N after the throttle valve is opened when the engine stop speed is reduced because the idling stop condition is satisfied. It is determined whether to continue the normal rotation of 1 or to reverse the rotation by completely stopping the rotation of the engine 1. Then, the ECU 2 drives the starter generator 20 based on the determination result. As a result, when the engine rotational speed N has recovered to a predetermined value, the engine 1 is restarted.

  Next, a system configuration of the engine start control device according to the present embodiment will be described with reference to FIG. FIG. 4 is a functional block diagram of the engine start control device according to the present embodiment. The engine start control device 3 is configured to stop the engine 1 (see FIG. 1) when a throttle valve (not shown) is closed and restart the engine 1 when the throttle valve is opened. The engine start control device 3 is configured to change the driving method of the crankshaft 10 (see FIG. 1) according to the engine rotation speed at a predetermined crank position when the engine 1 is restarted. For this reason, even when the engine 1 rotates at a low speed or stops rotating, the engine 1 can be reliably restarted.

  The opening degree (opening degree) of the throttle valve is adjusted by the occupant's throttle operation. The opening of the throttle valve is detected by a throttle opening sensor 31 provided in the throttle valve. The throttle opening detected by the throttle opening sensor 31 is output to the ECU 2. The rotational speed of the engine 1 (crankshaft 10) is detected by a crank angle sensor 32 provided on the outer periphery of the crankshaft 10 (see FIG. 1). The crank angle sensor 32 is constituted by a Hall element, for example, and acquires a crank pulse from the crankshaft 10. The crank pulse acquired by the crank angle sensor 32 is output to the ECU 2. The ECU 2 calculates a crank rotation speed (engine rotation speed) and a crank position from the crank pulse. In the present embodiment, the crank angle sensor 32 and a part of the ECU 2 constitute detection means.

  The ECU 2 includes a storage unit 21 that stores threshold values (NE1, NE2, NE3 shown in FIG. 3) that serve as determination criteria for controlling the drive of the starter generator 20. Each threshold value may be configured by map data changed in accordance with the throttle opening degree, the intake air temperature, and the engine water temperature. Thereby, a threshold value can be selected according to the surrounding environment of the engine 1, and the forward / reverse determination of the engine 1 with higher accuracy can be made.

  Note that the larger the throttle opening, the greater the amount of air taken into the engine 1, and the higher the pressure in the cylinder 11 during the compression stroke. For this reason, the torque required to overcome the compression top dead center when starting the engine is also increased. Here, as the data for the above determination, the starter generator 20 can be driven more accurately by increasing the predetermined rotational speed NE2 (threshold) as the throttle opening increases in accordance with the throttle opening. Can be determined.

  Further, since the amount of air taken into the engine 1 increases as the intake air temperature decreases, the pressure inside the cylinder 11 during the compression stroke increases. For this reason, the torque required to overcome the compression top dead center when starting the engine also increases. Here, as the data for the above determination, the driving method of the starter generator 20 is more accurately determined by increasing the predetermined rotational speed NE2 (threshold value) as the intake air temperature decreases in accordance with the intake air temperature. be able to.

  Furthermore, the lower the engine water temperature, the higher the viscous resistance of the engine oil, and the greater the torque required to overcome the compression top dead center when starting the engine. Here, as the data for the above determination, the driving method of the starter generator 20 can be determined more accurately by increasing the predetermined rotational speed NE2 (threshold value) as the engine water temperature decreases in accordance with the engine water temperature. .

  In addition, the ECU 2 includes a determination unit 22 that compares the calculated engine rotation speed with each threshold value stored in the storage unit 21 to determine the operation mode of the starter generator 20. Determination unit 22 sets an operation mode flag MF (hereinafter simply referred to as MF) of starter generator 20 according to the determination result. The set MF is temporarily stored in the storage unit 21. The determination method of the determination unit 22 and each MF will be described later. Then, the ECU 2 controls the operation of the starter generator 20 based on the set MF, and drives the crankshaft 10. As described above, the ECU 2 controls the fuel injection device 33 (fuel injection amount) and the ignition device 19 (ignition timing) according to various parameters such as the vehicle speed and the intake pressure. In addition, ECU2 comprises the control means which concerns on this Embodiment.

  Next, a method of change of mind control will be described in detail with reference to FIG. FIG. 5 is a graph showing the in-cylinder pressure with respect to the crank position in FIG. 3B or FIG. 3C of the engine according to the present embodiment.

  As shown in FIG. 5, in the change-of-mind control according to the present embodiment, after the throttle operation is detected from the idling stop state, the crankshaft 10 (see FIG. 1) is moved to the predetermined crank position (predetermined in the compression stroke). It is forcibly driven to a position (more specifically, a substantially midpoint of the compression stroke). As shown in FIG. 5A, if the crankshaft 10 can be rotated to a predetermined crank position, the engine 1 (see FIG. 1) is driven to rotate forward based on the engine rotational speed detected at the predetermined crank position. It is determined whether to drive in reverse.

  For example, in FIG. 5A, as a result of the throttle operation being performed in the exhaust stroke, the crankshaft 10 is forcibly driven, and the crankshaft 10 reaches a predetermined crank position (see arrow A). At this time, the engine speed is detected. When the detected engine rotational speed is greater than the predetermined rotational speed NE2 (forward rotation continuation determination rotational speed: see FIG. 3), the determination unit 22 (see FIG. 4) continues the forward drive of the crankshaft 10. Judge that. The crankshaft 10 is driven to rotate forward by the starter generator 20 as it is. As a result, when the engine rotational speed exceeds a predetermined rotational speed NE1 (starting completion determination rotational speed: see FIG. 3), the engine 1 is restarted (see arrow B).

  Even if the crankshaft 10 can be rotated to a predetermined crank position, if the detected engine speed is lower than NE2, the crankshaft 10 will overcome the compression top dead center and start the engine 1 It is determined that the rotation speed is not sufficient. At this time, the determination unit 22 determines to drive the crankshaft 10 in the reverse direction. For this reason, the crankshaft 10 is reversely driven by the starter generator 20 and returned to a predetermined position (in the vicinity of the explosion stroke start position in FIG. 5A), and then is driven forward again (see arrow C). As described above, as a result of returning the crankshaft 10 to the preparation position for restarting, a rotational speed sufficient to overcome the compression top dead center can be obtained, and the engine 1 is restarted.

  On the other hand, as shown in FIG. 5B, when the throttle operation is detected and the crankshaft 10 is driven forward, the engine speed falls below a predetermined speed NE3 (engine stop determination speed: see FIG. 3). The crankshaft 10 cannot reach the predetermined crank position, and the engine rotation speed cannot be detected at the predetermined crank position (see arrow D). At this time, the determination unit 22 determines to drive the crankshaft 10 in the reverse direction. The crankshaft 10 is forcibly reversely driven by the starter generator 20. Then, as a result of the forward rotation driving after the crankshaft 10 is returned to a predetermined position, as described above, a rotational speed sufficient to overcome the compression top dead center can be obtained, and the engine 1 is restarted ( (See arrow E). As described above, after the throttle operation is recognized, the engine 1 is driven to rotate forward, and the operation of the starter generator 20 is controlled according to the engine rotational speed at the predetermined crank position.

  In this way, by setting the predetermined crank position as the compression stroke, it is possible to determine whether the crankshaft 10 continues to rotate in the normal direction and reversely rotates in the compression stroke where the driving load of the engine 1 is the highest. Thereby, it is possible to more accurately determine whether or not it is necessary to reverse the crankshaft 10 to the preparation position. In addition, the predetermined rotational speed NE2 that serves as a reference for this determination may be set only by the predetermined crank position, and the number of steps for obtaining the predetermined rotational speed NE2 through experiments or the like can be reduced. As a result, the predetermined rotational speed NE2 can be configured with a single data. Therefore, the amount of data stored in the ECU 2 can be reduced as compared with the map data configured with threshold values (predetermined rotational speeds) corresponding to all crank positions as in the conventional case.

  Hereinafter, the flow of the idling stop control and the change of mind control according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing an example of engine restart control according to the present embodiment. First, as a premise that this control is started, it is assumed that an idling stop condition is satisfied and fuel injection and ignition control are stopped. The control described below is executed by the ECU 2 unless otherwise specified.

  As shown in FIG. 6, when the control is started, first, the operation mode flag MF = “non-energized” is set (step ST1). Here, the operation mode indicates the type of operation of the starter generator 20 (see FIG. 1). In the following description, in addition to “no energization”, there are a total of four operation modes of “power generation”, “forward rotation driving”, and “reverse rotation driving”.

  When MF = “non-energized” is set in step ST1, the operation of starter generator 20 is turned off. As a result, the crankshaft 10 is inertially rotated, and the rotational speed thereof gradually decreases due to a mechanical load (weight of the crankshaft 10, friction between components, etc.). Then, the crank pulse acquired by the crank angle sensor 32 (see FIG. 4) is read, and the rotational speed N (hereinafter simply referred to as rotational speed N) and the crank position of the crankshaft 10 are calculated (step ST2). Further, the output value of the throttle opening sensor 31 (see FIG. 4) is read, and the throttle opening is detected (step ST3).

  Next, it is determined whether or not the calculated rotational speed N is equal to or higher than a predetermined rotational speed NE1 (starting completion determination rotational speed (hereinafter simply referred to as NE1)) (step ST4). In step ST4, it is determined from the rotational speed N whether or not the engine 1 has been started, that is, whether or not the engine 1 needs to be restarted. If the engine speed is NE1 or higher (step ST4: YES (Y)), MF = “power generation” is set (step ST5), and the control is terminated. At this time, the starter generator 20 starts power generation.

  In step ST4, when the rotational speed N is not equal to or higher than NE1 (step ST4: NO (N)), the rotational speed N is a predetermined rotational speed NE3 (crank stop determination rotational speed (hereinafter referred to as NE3)) or the crankshaft 10 is reversed. It is determined whether or not it is in a state (step ST6). When the rotation speed N is NE3 or less or in the reverse rotation state (step ST6: YES), it is determined whether MF = “forward rotation driving” or MF = “reverse rotation driving” is set (step ST7). . In step ST7, according to the set MF, whether or not to perform control to rotate the crankshaft 10 forward after being rotated to the preparation position for restarting (hereinafter referred to as swingback control (SB control)) is performed. Is judged. Here, the preparation position refers to the normal rotation of the crankshaft 10 as a result of the crankshaft 10 reversing the explosion stroke to increase the pressure in the cylinder 11 (see FIG. 1) and lower the rotational speed of the crankshaft 10. The position that turns to.

  When MF = “forward rotation driving” or MF = “reverse rotation driving” is set (step ST7: YES), the swing back control described above is performed (step ST8). As a result, the rotational speed N is increased to NE1, and the control is terminated. When MF = “forward rotation driving” or MF = “reverse rotation driving” is not set (step ST7: NO), it is determined that the idling stop control is normal, and the stop position control shown in FIG. 3A is performed. (Step ST9). Specifically, the crankshaft 10 is driven forward or reversely, and the crankshaft 10 is positioned at an optimal position for restarting the engine 1. Then, the control ends.

  In step ST6, when the rotational speed N is NE3 or less or the crankshaft 10 is not in the reverse rotation state (step ST6: NO), whether MF = “forward rotation driving” or MF = “reverse rotation driving” is set. Determination is made (step ST10). If MF = “forward rotation driving” or MF = “reverse rotation driving” is not set (step ST10: NO), it is determined whether the throttle valve is opened (step ST14).

  When the throttle valve is opened (step ST14: YES), MF = “forward rotation drive” is set (step ST15) on the assumption that there is an intention to restart the engine 1. As a result, the starter generator 20 is driven in the normal direction, and the process returns to step 2. On the other hand, when the throttle is not opened (step ST14: NO), it returns to step ST2 as it is, assuming that there is no intention to restart the engine 1. Then, the rotational speed N is detected again. Thus, in step ST14, it is determined whether or not the restart control of the engine 1 is to be performed based on the presence or absence of the throttle operation.

  In step ST10, when MF = “forward rotation driving” or MF = “reverse rotation driving” is set (step ST10: YES), it is determined whether or not the crankshaft 10 has passed the predetermined crank position (step ST10: YES). Step ST11). When the crankshaft 10 has not passed the predetermined crank position (step ST11: NO), the process returns to step ST2.

  When the crankshaft 10 has passed the predetermined crank position in step ST11 (step ST11: YES), it is determined whether or not the rotational speed N at the predetermined crank position is smaller than NE2 (step ST12). In step ST12, as shown in FIG. 5A, it is determined according to the rotational speed N whether the crankshaft 10 is driven to rotate forward or reversely.

  If the rotational speed N is not smaller than NE2 in step ST12 (step ST12: NO), it is determined that there is no need to reverse the crankshaft 10, and the forward rotation drive of the crankshaft 10 is continued. Then, the process returns to step ST2.

  In step ST12, when the rotational speed N is smaller than NE2 (step ST12: YES), MF = “reverse driving” is set (step ST13). That is, it is determined that the crankshaft 10 cannot exceed the compression top dead center at a rotational speed N lower than NE2. In this case, the determination unit 22 drives the starter generator 20 to operate the brake. As a result, the rotational speed N is reduced, and the process returns to step ST2.

  As described above, when the process returns to step ST2 after the process from step ST11 to step ST15, each process described above is performed again. Then, the operation of starter generator 20 is controlled according to the MF at that time. This control is repeated until the engine 1 is restarted or until the engine 1 is completely stopped at a normal idling stop.

  For example, if NO is returned in step ST11 and the process returns to step ST2, as a result of detecting the rotational speed N again, if the rotational speed N detected again is equal to or lower than NE3 (step ST6: YES), swing back is performed in step ST8. Control is implemented. As a result, the rotational speed N is increased to NE1, and the control is terminated.

  Further, when NO is returned in step ST12 to step ST2, the rotational speed N is detected again. In this case, since the rotation speed N is increased by continuing the forward rotation drive, if the rotation speed N detected again in step ST2 is equal to or higher than NE1 (step ST4: YES), the engine 1 is restarted. It is determined that the engine has started, and the control ends.

  Further, when the process returns to step ST2 via step ST13, if the rotation speed N is detected again as a result of the detection of the rotation speed N again (step ST6: YES), the swingback control is performed in step ST8. Is implemented. As a result, the rotational speed N is increased to NE1, and the control is terminated. Note that, by controlling the brake, the decrease in the rotation speed N is promoted, and the time until the rotation of the engine 1 is stopped can be shortened. Therefore, the transition to the swingback control becomes smooth, and the responsiveness of engine restart can be improved.

  As described above, according to the present embodiment, when restarting after the engine 1 stop control is started, the determination of the driving method (forward rotation driving or reverse rotation driving) of the engine 1 is made based only on the engine speed at the predetermined crank position. It can be carried out. In this case, it is only necessary to investigate only the engine speed at a predetermined (single) crank position when setting NE2 as a determination criterion. Therefore, the man-hour for determining NE2 can be reduced. Therefore, for example, when the same engine start control device 3 is applied to an engine of another model, the development man-hour can be reduced. Further, since the above determination is performed at a predetermined crank position, NE2 serving as a determination reference can be composed of a single data. For this reason, compared with the map data comprised by the threshold value corresponding to all the crank positions like the past, the data amount stored in ECU2 can be reduced.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above embodiment, the engine rotation speed is detected at a predetermined position in the compression stroke. However, the present invention is not limited to this structure. The part for detecting the engine rotation speed may be, for example, before or after the compression top dead center or the compression top dead center.

  Moreover, in the said embodiment, although it was set as the structure which restarts the engine 1 with the starter generator 20, it is not limited to this structure. A starter motor and a generator may be provided separately, and the engine 1 may be restarted by the starter motor.

  In the above embodiment, when the crankshaft 10 is driven in reverse by the starter generator 20, the ECU 2 (control means) starts the starter at the timing when the forward rotation of the crankshaft 10 is reversed (stopped) by the internal pressure of the cylinder 11. The generator 20 may be reversely controlled. In this case, the driving load of the starter generator 20 can be reduced, and as a result, current consumption can be reduced.

  As described above, the present invention has the effect that engine restart can be realized without reducing the development man-hours and without increasing the amount of map data stored in the ECU. This is useful for an engine start control device that restarts the engine after idling stop.

1 engine 2 ECU (control means)
3 Engine start control device 20 Starter generator 32 Crank angle sensor (detection means)

Claims (10)

An engine start control device for stopping the engine when the throttle valve is closed, and starting the engine when the throttle valve is opened after the engine is stopped;
Detection means for detecting engine rotation speed;
When the engine rotational speed at a predetermined crank position is equal to or higher than a threshold value after opening the throttle valve, the engine is driven forward, while when the engine rotational speed is smaller than the threshold value, An engine start control device comprising: control means for forwardly driving the engine.   2. The engine start control device according to claim 1, wherein the control means drives the engine forward to the predetermined crank position after opening the throttle valve.   The control means drives the engine in the normal direction after driving the engine in the reverse direction when the engine rotation speed falls below a threshold value in the process of driving the engine in the normal direction to the predetermined crank position. The engine start control device according to claim 2.   4. The engine start control device according to claim 3, wherein the threshold value is increased as the throttle opening degree increases in accordance with the throttle opening degree.   4. The engine start control device according to claim 3, wherein the threshold value is increased as the intake air temperature decreases in accordance with the intake air temperature.   4. The engine start control device according to claim 3, wherein the threshold value is increased as the engine water temperature decreases in accordance with the engine water temperature.   The engine start control device according to any one of claims 1 to 6, wherein the control means performs brake control of the engine before the engine is driven in reverse.   8. The engine start control device according to claim 7, wherein when the engine is driven in reverse rotation, the control means performs reverse rotation control at a timing at which the rotation of the engine stops due to cylinder internal pressure.   The engine start control device according to any one of claims 1 to 8, wherein the control means executes driving of the engine by a starter generator.   The engine start control device according to any one of claims 1 to 9, wherein the control means determines an engine rotation speed at a crank position in a compression stroke as the predetermined crank position.

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