JP2006200385A - Starter for internal combustion engine - Google Patents

Abstract

In an internal combustion engine that is started by combustion in a specific cylinder, the combustion gas is sufficiently scavenged when the engine is stopped.
When the engine is stopped, the engine speed is increased prior to stopping the ignition (S201 to 203), and the number or angle of rotation of the engine after the ignition is stopped is ensured.
[Selection] Figure 4

Description

  The present invention relates to a starter for an internal combustion engine, and more particularly, to a technique for starting an engine by combustion in a specific cylinder without using a starter employing an electric motor or the like.

The following are known as so-called starterless starters that do not depend on a starter. That is, when starting the engine, the cylinder stopped in the expansion stroke at the time of the previous stop is determined, combustion is caused in the determined cylinder, and the engine is rotated and triggered by this combustion (patent document). 1).
Japanese Patent Laid-Open No. 02-271073 (page 2, upper left column, lines 7 to 14)

  However, this known starting device has the following problems. That is, when the engine is stopped, the engine does not immediately stop rotating due to the stop of ignition (that is, combustion), but stops completely after rotating somewhat inertially. The number or angle of rotation of the engine between the stop of ignition and the complete stop varies among individuals depending on the inertia of the engine and the magnitude of friction, etc. It changes according to general conditions. In consideration of the next start, for a general internal combustion engine, it is preferable that the engine rotates twice or more from the stop of ignition and the combustion gas is sufficiently scavenged in all cylinders. However, if the inertial rotation after ignition stops varies or changes due to the above reasons and combustion gas is not sufficiently scavenged, the burned gas remains in the cylinder at the next start. By doing so, it is considered that the combustion for starting is not performed well and the starting cannot be performed quickly.

  It is an object of the present invention to ensure the number of times the engine rotates after stopping the ignition and sufficiently scavenge the combustion gas in all the cylinders when the engine is stopped.

  The present invention provides a starter for an internal combustion engine. The device according to the present invention is a starting device for an internal combustion engine that starts by rotating by ignition in a specific cylinder stopped in an expansion stroke, and determines whether or not a predetermined condition for stopping the engine is satisfied. At the same time, when it is determined that the predetermined condition is satisfied, the engine speed is increased and then the ignition is stopped.

  According to the present invention, when the engine is stopped, the number of rotations of the engine after stopping the ignition can be ensured by increasing the number of rotations of the engine before stopping the ignition. For this reason, the engine can be reliably rotated as many times as necessary for scavenging the combustion gas, and the scavenging can be sufficiently performed in all the cylinders. be able to.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a configuration of an internal combustion engine (hereinafter referred to as “engine”) 1 according to an embodiment of the present invention. In this embodiment, a so-called direct injection gasoline engine is employed as the engine 1.
A piston 12 is inserted into the cylinder block 11, and a space formed between the crown surface 121 of the piston 12 and the lower surface of the cylinder head 13 becomes a combustion chamber 14. The piston 12 is connected to the crankshaft 17 via the connecting rod 15 and the crank arm 16, and the crankshaft 17 rotates in conjunction with the reciprocating motion of the piston 12. In the present embodiment, the piston boss center 122 is set on the cylinder center axis m in the section of FIG. 1 including the cylinder center axis m. The piston boss center 122 is connected to the connecting rod 15 and the crank in this section. The connecting portion c with the arm 16 may be set to be offset to a position passing through the center 122 and passing on a straight line parallel to the cylinder center axis m before the top dead center.

  The cylinder head 13 is formed with an intake port 18 on one side with respect to the cylinder central axis m, and the intake port 18 is connected to an intake manifold (not shown) to form an intake passage. The intake port 18 is opened and closed by an intake valve 19. On the other hand, an exhaust port 20 is formed on the other side with respect to the cylinder center axis m, and the exhaust port 20 is connected to an exhaust manifold (not shown) to form an exhaust passage. The exhaust port 20 is opened and closed by an exhaust valve 21. Two intake ports 18 and two exhaust ports 20 are juxtaposed in the cylinder arrangement direction, two for each cylinder. The intake valve 19 and the exhaust valve 21 are respectively driven by an intake cam and an exhaust cam (not shown) installed above the valves 19 and 21. In the present embodiment, an intake control valve 71 is provided for idle speed control described later. The intake control valve 71 is installed in a bypass passage that bypasses a not-shown throttle valve (provided in the intake passage). When the throttle valve is of an electronic control type, this throttle valve can also function as the intake control valve 71.

  The cylinder head 13 is provided with a fuel supply injector 22 facing the combustion chamber 14, and fuel is directly injected into the combustion chamber 14 by the injector 22. In the present embodiment, the injector 22 is disposed between the two intake ports 18, 18, and fuel is injected from the side into the combustion chamber 14. An ignition plug 23 for igniting the fuel injected by the injector 22 is installed on the cylinder central axis m. The operations of the injector 22 and the spark plug 23 are controlled by an engine control unit 31 described later.

  The operation of the engine 1 is integrally controlled by an engine control unit (hereinafter referred to as “ECU”) 31. The ECU 31 receives a signal from the accelerator sensor 41 for detecting the accelerator opening, a signal from the crank angle sensors 42 to 44 (based on this, the engine speed can be calculated), and the coolant temperature. A signal from the temperature sensor 45 to be detected is input, and signals from the operation switch 46 of the power steering device, the operation switch 47 of the air conditioner, the operation switch 48 of the alternator, the ignition switch 49 and the start switch 50 are input. The The ECU 31 calculates and sets the injection amount and injection timing of the fuel injection valve 22 and the ignition timing of the ignition device 23 based on these signals.

  In particular, the ECU 31 performs idle stop control for temporarily stopping the engine 1 until a predetermined idle stop condition established for a vehicle speed or the like is satisfied and until an idle stop release condition is satisfied thereafter. In the present embodiment, in order to detect an accurate stop position of the crankshaft 17 at the time of this idle stop, three sensors 42 to 44 are installed as crank angle sensors. Of these, the two sensors 42 and 43 are provided for the first rotor 61 attached to the crankshaft 17. The first rotor has irregularities formed on the outer periphery at intervals of 30 degrees, and the sensors 42 and 43 output position signals every 30 degrees in terms of crank angle in accordance with the irregularities. The sensors 42 and 43 are arranged so as to be shifted by 15 deg in the circumferential direction around the crankshaft 17, and output this position signal with a phase shift of 15 deg from each other. The remaining one sensor 44 is provided for a second rotor (not shown) attached to the camshaft. The second rotor has one protrusion formed on the outer periphery, and the sensor 44 outputs a reference signal every 720 degrees in crank angle as the protrusion passes. The crank angle sensors 42 to 44 can detect the stop position of the crankshaft 17 with an accuracy of 15 deg. The ECU 31 determines the cylinder stopped in the expansion stroke at the time of idling stop and causes combustion in the determined cylinder based on the detected stop position when restarting after the idling stop. The engine 1 is triggered by this combustion. Rotate to start. The engine speed can be detected by counting the position signals from the sensors 42 and 43 over a predetermined period or measuring the generation period of the reference signal from the sensor 44.

Next, detection of the stop position of the crankshaft 17 by the crank angle sensors 42 to 44 will be described with reference to FIG.
FIG. 2 shows output waveforms of the crank angle sensors 42 to 44 when the engine 1 is stopped.
The ECU 31 is set with a position counter CNT that takes a value of 1 to 48, and the ECU 31 detects the stop position of the crankshaft 17 based on the value of the position counter CNT at the time of stop. As described above, the position signals POS1 and POS2 from the sensors 42 and 43 are input every 30 degrees with a phase shift of 15 degrees. The position counter CNT is reset to 1 (angle ANG1) by the input of the next position signal (here, POS1) to which the reference signal REF is input, and is incremented by 1 for each input of the position signals POS1 and POS2. When the position signals POS1 and POS2 from the sensors 42 and 43 are alternately input, the position counter CNT is incremented by 1 when the position signals POS1 and POS2 are input. However, when the engine 1 is stopped, the position counter CNT rotates completely. When the crankshaft 17 is reversely rotated immediately before stopping, the position signal (here, POS2) from one sensor is continuously input (angle ANG2). In this case, by subtracting 1 from the position counter CNT, it is possible to detect a stop position taking into account reverse rotation. Whether or not the rotation has completely stopped can be determined by the absence of any input of the position signals POS1 and POS2 over a predetermined period (angle ANG3).

Below, operation | movement of ECU31 is demonstrated with a flowchart.
FIG. 3 is a flowchart of the idle control routine. This routine is started when the ignition switch 49 is turned on, and then executed at a predetermined cycle. According to this routine, the engine 1 idle speed control, idle stop, and restart after idle stop are performed.

  In S101, it is determined whether a predetermined idle condition is satisfied. When this condition is satisfied, the process proceeds to S102, and when this condition is not satisfied, this routine is returned. In the present embodiment, a) the accelerator opening is equal to or less than a predetermined value and the accelerator pedal is completely returned, and b-1) the vehicle speed is at a low vehicle speed equal to or less than the predetermined value or b. -2) Shifts to the next idle speed control on condition that the shift lever of the transmission is in neutral. The vehicle speed can be calculated based on the engine speed, the transmission gear ratio, and the like.

  In S102, idle speed control is performed. This control may be performed by any known method, but in this embodiment, the target idle speed tNidl is set based on the coolant temperature, the load by the auxiliary machine, the position of the shift lever, etc., and the intake air amount By controlling this, the actual engine speed NE is controlled to the set target idle speed tNidl. That is, the difference between the target idle speed tNidl and the engine speed NE is calculated, and the intake control valve 71 is opened and closed based on the calculated difference, so that the engine speed NE matches the target idle speed tNidl.

  In S103, it is determined whether or not a predetermined idle stop condition is satisfied. When this condition is satisfied, the process proceeds to S104, and when this condition is not satisfied, this routine is returned. In the present embodiment, the idling stop is performed on the condition that a) a substantially stopped state where the vehicle speed is equal to or lower than a predetermined value continues for a predetermined time, and b) the cooling water temperature is equal to or higher than the predetermined temperature. Execute.

In S104, stop control is executed according to the flowchart shown in FIG.
In S105, it is determined whether or not a predetermined idle stop cancellation condition is satisfied. When this cancellation condition is satisfied, the process proceeds to S106, and when it is not satisfied, the process of S105 is repeated. In the present embodiment, the idling stop is canceled on the condition that the accelerator sensor 41 detects an accelerator opening greater than or equal to a predetermined value and determines that the accelerator pedal is depressed.

In S106, based on the stop position of the crankshaft 17, it is determined which cylinder has stopped in the expansion stroke at the time of idling stop, fuel injection and ignition are performed on this cylinder, combustion occurs, and the engine 1 is Start.
FIG. 4 is a flowchart of a stop control routine.
In S201, the engine speed is increased prior to idling stop. In the present embodiment, as the target engine speed of the engine 1, a pre-stop target engine speed tNstp larger than the target idle engine speed tNidl before the establishment of the idle stop condition is set, and the engine engine speed is set so as to coincide with this. By controlling, the engine speed is increased. The target rotation speed before stop tNstp is set by adding the correction value DLT searched from the trend table shown in FIG. 6 to the basic target rotation speed tNstp0 before stop searched from the trend table shown in FIG. tNstp = tNstp0 + DLT). In the table of FIG. 5, the basic target rotational speed tNstp0 before stop is generally set to a value larger than the target idle rotational speed tNidl, and the difference δNstp from the target idle rotational speed tNidl is low. It is set to become larger. In this embodiment, when the cooling water temperature Tw is equal to or higher than the predetermined value Tw1, the rotational speeds tNstp0 and tNidl of both are made to coincide with each other. The rotational speed tNstp0 may be set to a value larger than the target idle rotational speed tNidl. On the other hand, in the table of FIG. 6, the correction value DLT is set according to the load by the auxiliary machine. In this embodiment, a power steering device and an alternator are employed as the auxiliary machine. The correction value DLT is set to a relatively large value A when it is determined that both of the auxiliary machines are operating based on the signals from the switches 46 and 48, and only one of the auxiliary machines is set. When it is determined that it is operating, it is set to a value B smaller than this value A, and when it is determined that all of the auxiliary machines are stopped, the smallest value C (C <B <A ).

  The correction value DLT may be changed not only according to the operating state of the auxiliary machine, that is, not only depending on the operation or stop of the power steering device but also according to the magnitude of the load. In this case, in addition to the switches 46 and 48, a sensor for detecting a load by the auxiliary machine is installed. For example, the load by the alternator can be detected based on the generated power of the alternator. The correction value DLT is not limited to the load by the alternator, but may be changed according to the load by the air conditioner. The load by the air conditioner can be calculated based on the flow rate of the blower constituting the air conditioner.

In S202, a predetermined device is driven to increase the engine speed. In the present embodiment, the intake air amount is increased by operating the intake control valve 71 or the ignition timing is advanced. When using the former method, the engine speed can be significantly increased, and when using the latter method, the engine speed can be increased with high response.
In S203, it is determined whether or not the actual engine speed NE has reached the pre-stop target speed tNstp. If it has reached, the process proceeds to S204, and if it has not reached, the processes of S202 and 203 are repeated.

In S204, for idling stop, the output of the energization signal to the ignition coil of the spark plug 23 is shut off, and ignition in all the cylinders is stopped.
In S205, output of the drive signal to the solenoid of the injector 22 is shut off, and fuel injection in all cylinders is stopped.
Regarding the present embodiment, the process of S101 in the flowchart shown in FIG. 3 is “stop determination means”, the process of S201 to 203 in the flowchart of FIG. 4 is “rotation control means”, and the process of S204 in the flowchart is “ignition”. In the “stop means”, the coolant temperature sensor 45 corresponds to “temperature detection means”, and the injector 22 corresponds to “fuel injection means”.

According to this embodiment, the following effects can be obtained.
That is, in the present embodiment, the engine speed is increased prior to idling stop, and the engine speed is decreased from a higher speed tNspt until the rotation is completely stopped after the ignition is stopped. The number of times the engine 1 rotates can be secured. For this reason, at the time of idling stop, the engine 1 can be reliably rotated as many times as necessary for scavenging the combustion gas, and the scavenging can be sufficiently performed in all the cylinders. Can be started quickly.

  FIG. 7 shows this effect. Prior to the idling stop, a case where the engine speed is increased is indicated by a solid line, and a case where the normal target idling speed tNidl is maintained is indicated by a two-dot chain line. Since the inclination when the engine speed decreases after the ignition is stopped is not significantly different between the two cases, the rotation is completely stopped after the ignition is stopped (time t0) by increasing the engine speed. The angle until the crankshaft 17 rotates (hereinafter referred to as “stop rotation angle”) can be sufficiently secured. FIG. 7 shows that the engine speed is increased to the target engine speed tNstp before stopping, so that the engine 1 is rotated at a crank angle of 720 degrees or more after the ignition is stopped until the engine is completely stopped. It shows that the shaft 17 can be rotated more than once.

  In the present embodiment, the target rotation speed before stop tNstp is set based on the cooling water temperature Tw and the load by the auxiliary machine, so that the stop rotation angle can be reliably ensured regardless of environmental conditions. . That is, by detecting the coolant temperature Tw and performing an idling stop at an engine speed Nstp that is greatly increased from the target idle speed tNidl as the temperature is lower (FIG. 5), the friction increases due to changes in the environment and the like. Correspondingly, a stop rotation angle can be secured. On the other hand, by detecting the load by the auxiliary machine and performing an idle stop at the engine speed Nstp that is greatly increased from the target idle speed tNidl as the load increases (FIG. 6), the load is stopped regardless of the load on the auxiliary machine. A rotation angle can be secured. In order to reduce the influence of the environment or the like, the temperature of the lubricating oil or the ambient air temperature may be employed instead of the cooling water temperature Tw. In this case, a tendency similar to that shown in FIG. 5 can be given to the basic target rotational speed tNstp0 before stopping.

In the present embodiment, when the engine speed increases, the target speed after the increase (that is, the target speed tNstp before stop) itself is set based on the coolant temperature Tw and the like. However, the present invention is not limited to this, and it is also possible to calculate an increase amount δNstp of the rotational speed from the target idle rotational speed tNidl and add this to the target idle rotational speed tNidl.
Next, another embodiment of the present invention will be described.

FIG. 8 is a flowchart of the stop control routine according to the present embodiment. The configuration of the engine according to this embodiment is the same as that of the previous embodiment shown in FIG.
After the idle determination, the ECU 31 executes this stop control when a predetermined idle stop condition is satisfied.
Prior to the idling stop, with reference to the tendency tables shown in FIGS. 5 and 6, the pre-stop basic target speed tNstp0 and the correction value DLT are calculated, and the pre-stop target speed tNstp is set (tNstp = tNstp0 + DLT: S201). . A predetermined device such as the intake control valve 71 is driven based on the set pre-stop target speed tNstp (S202), and when the engine speed NE reaches the pre-stop target speed tNstp (S203), the spark plug 23 Is stopped (S204), and the injector 22 is stopped (S205).

In S301, an angle Astp in which the engine 1 has rotated between the stop of ignition (that is, combustion) and the stop of rotation completely is detected. The stop rotation angle Astp can be easily detected based on the outputs of the crank angle sensors 42 to 44.
In S302, the basic target rotation speed before stop tNstp0 is corrected based on the detected stop rotation angle Astp. In the present embodiment, the learning value HOSn is calculated by searching from the tendency table shown in FIG. 9 and added to the pre-stop basic target speed tNstp0 on the table (FIG. 5). In the table of FIG. 9, the learned value HOSn is set to a smaller value as the stop rotation angle Astp is larger, and is set to 0 for a stop rotation angle Astp of 720 degrees or more. This is because the stop rotation angle necessary for scavenging all the cylinders is secured. The correction of the basic target rotational speed before stop tNstp0 by the learning value HOSn is preferably performed for each region of the coolant temperature Tw. In FIG. 5, the basic target rotation speed tNstp0 before stop after the correction is indicated by a one-dot chain line. The correction of the basic target rotational speed before stop tNstp0 is reflected in the setting of the target rotational speed before stop tNstp (S201) at the next idle stop.

Regarding this embodiment, in particular, S301 in the flowchart shown in FIG. 8 corresponds to “stop rotation angle detection means”, and the processing in S201 to 203, 302 in the flowchart corresponds to “rotation control means”.
According to the present embodiment, at the time of idling stop, it is determined whether or not the scavenging of the combustion gas has been sufficiently performed in all the cylinders based on the stop rotation angle Astp. By increasing the basic target speed tNstp0, it is possible to perform idling stop at a higher engine speed Nstp at the time of the next idling stop and secure a stop rotation angle. For this reason, it is possible to reliably perform scavenging at the time of idling stop and maintain the startability of the engine 1 regardless of an increase in friction with time in the engine 1 or the like.

  In the above, the engine 1 is always started by combustion in a specific cylinder. However, in order to ensure startability when the engine 1 is cold, an electrically operated start motor is installed, When the cooling water temperature or the like does not reach a predetermined temperature upon restarting, the engine 1 may be cranked by the start motor and started.

In the above description, the restarting after the idle stop has been described. However, the present invention can also be applied when the engine 1 is stopped after the ignition switch is turned off.
Further, the case where the direct injection type engine is employed as the engine 1 has been described above. However, the present invention is such that the fuel supply injector is installed facing the intake passage, and the fuel and air are preliminarily taken in before intake. It can also be applied to those to be mixed. In this case, when the engine 1 is stopped, only the ignition is stopped and the fuel injection is continued, so that the engine 1 is stopped in a state where the air-fuel mixture is filled in the cylinder.

Configuration of an internal combustion engine according to an embodiment of the present invention Change of position counter with respect to output from crank angle sensor Idle control routine flowchart Stop control routine flowchart Table data of basic target speed tNstp0 before stop Table data of correction value DLT of target rotational speed before stop for load by auxiliary machine Effect of increasing engine speed before idling stop Flowchart of stop control routine according to another embodiment of the present invention Table data of learning value HOSn of target rotation speed before stop

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 11 ... Cylinder block, 12 ... Piston, 13 ... Cylinder head, 14 ... Combustion chamber, 15 ... Connecting rod, 16 ... Crank arm, 17 ... Crankshaft, 18 ... Intake port, 19 ... Intake valve, 20 ... Exhaust Port, 21 ... Exhaust valve, 22 ... Injector, 23 ... Spark plug, 31 ... Engine control unit, 41 ... Accelerator sensor, 42, 43 ... Unit angle sensor, 44 ... Reference angle sensor, 45 ... Cooling water temperature sensor, 46 ... Power steering operation switch, 47 ... air conditioner operation switch, 48 ... alternator operation switch, 49 ... ignition switch, 50 ... start switch, 61 ... rotor for unit angle detection, 71 ... intake control valve.

Claims (9)

A starter for an internal combustion engine that starts by rotating by ignition in a specific cylinder stopped in an expansion stroke,
Stop determination means for determining whether or not a predetermined condition for stopping the engine is satisfied;
A rotation control means for increasing the engine speed when it is determined by the stop determination means that the predetermined condition is satisfied;
An internal combustion engine starter comprising: ignition stop means for stopping ignition after the engine speed is increased by the rotation control means.   2. The internal combustion engine starter according to claim 1, wherein the rotation control means increases the engine speed to a predetermined target speed.   The internal combustion engine starter according to claim 1, wherein the rotation control means changes the engine speed by a predetermined value before and after the predetermined condition is satisfied.   The starter for an internal combustion engine according to any one of claims 1 to 3, wherein the rotation control means increases the flow rate of the intake air to increase the engine speed.   The starter for an internal combustion engine according to any one of claims 1 to 4, wherein the rotation control means advances the ignition timing to increase the engine speed. It further comprises temperature detecting means for detecting the temperature inside or around the engine,
The start of the internal combustion engine according to any one of claims 1 to 5, wherein the rotation control means changes an increase in the number of rotations before the predetermined condition is satisfied according to the temperature detected by the temperature detection means. apparatus. The engine further includes an auxiliary machine that generates a load in an operating state,
The starter for an internal combustion engine according to any one of claims 1 to 6, wherein the rotation control means changes an increase in the number of rotations before the predetermined condition is satisfied in accordance with a load by the auxiliary machine. When the engine is stopped, the engine further comprises stop rotation angle detection means for detecting a stop rotation angle at which the engine has rotated between the stop of ignition by the ignition stop means and the substantial stop of the engine,
When the engine is stopped next time, the rotation control means determines the amount of increase in the number of revolutions from before the predetermined condition is satisfied, depending on the stop rotation angle detected by the stop rotation angle detection means. The starter for an internal combustion engine according to any one of claims 1 to 7, wherein A fuel injection means for directly injecting the fuel into the combustion chamber;
When the engine is stopped, the fuel injection by the fuel injection unit is stopped together with the ignition stop by the ignition stop unit, and the fuel is injected into the specific cylinder by the fuel injection unit at the next start of the engine. The internal combustion engine starter according to claim 1, wherein the engine is rotated by ignition in the specific cylinder.

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