JP3841058B2 - Engine starter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine starter that automatically stops an engine temporarily when idling or the like and then automatically restarts the engine thereafter.
[0002]
[Prior art]
In recent years, fuel consumption reduction and CO ₂ In order to reduce emissions, etc., the engine is automatically stopped when idling, and then automatically restarted when a restart condition such as a start operation is established (hereinafter referred to as idle stop or I / S). Such engine starting devices have been developed.
[0003]
Since restart at idle stop is required to start immediately according to the start operation etc., start that starts the engine through cranking that drives the engine output shaft by a starter (starting motor) Conventional general start-up methods that require considerable time to complete are not preferred.
[0004]
Therefore, it is desirable to supply fuel to specific cylinders (cylinders in the expansion stroke) of the stopped engine to cause ignition and combustion so that the engine can be started immediately with that energy. However, even if fuel is supplied to a cylinder in the expansion stroke and ignited, combustion does not always occur, and even if combustion occurs, sufficient torque for starting the engine is not always obtained. In order to perform a smooth restart, an ignitability that exceeds a certain level and a magnitude of generated torque are required.
[0005]
As a countermeasure against such a problem, for example, as disclosed in Patent Document 1, a brake device is provided for the crankshaft of the engine so that the piston of the cylinder that is in the expansion stroke when the engine is stopped stops at an appropriate position during the stroke. As shown in Japanese Patent Application Laid-Open No. 2003-28190 or Patent Document 2, after IG OFF (ignition stop), the closing timing of the exhaust valve is controlled to stop the engine with the piston in the proper position. Something that has been made easier has been proposed.
[0006]
The proper stopping position of the piston for restarting is generally around 90 ° CA (crank angle) after top dead center, that is, near the middle of top dead center and bottom dead center, and the piston is stopped at this position. If it does, favorable combustion will be obtained with the cylinder air which exists moderately, and the fuel supplied at the time of restart, and it will be easy to generate sufficient torque for restart. That is, Patent Document 1 and Patent Document 2 attempt to regulate the stop position of the piston so that a sufficient restart torque can be obtained by combustion.
[0007]
[Patent Document 1]
Japanese Utility Model Publication No. 60-128975
[Patent Document 2]
WO 01/44636 A2 publication
[0008]
[Problems to be solved by the invention]
The starting device disclosed in Patent Document 1 requires a device that can brake the crankshaft separately from the vehicle braking device, which complicates the mechanism, and also provides the braking device so that the piston stops at an appropriate position. It is very difficult to control with high accuracy.
[0009]
Further, the starting device disclosed in Patent Document 2 closes the exhaust valve at an appropriate time to confine gas in the cylinder so as to increase the in-cylinder pressure when the piston is near top dead center. For this reason, burnt gas (exhaust gas) tends to remain in the cylinder, which is a factor that deteriorates restartability.
[0010]
Not only in Patent Document 2, but generally during the idling operation in which the idling stop is performed, the intake amount is small, so that scavenging when the engine is stopped tends to be insufficient. Therefore, even if the piston is stopped at an appropriate position to improve restartability, on the other hand, combustion at the time of restart is hindered by the burnt gas remaining in the cylinder, and the effect of improving restartability is diminished. was there.
[0011]
In particular, when a throttle valve is provided upstream from the branch portion of the intake passage, the intake volume is large and the delay of the intake system tends to increase. In a state where the air-fuel ratio is the stoichiometric air-fuel ratio or richer than that, the throttle valve is almost fully closed, so scavenging when the engine is stopped becomes insufficient, and deterioration of startability is difficult to avoid.
[0012]
In view of the above circumstances, the present invention makes it easy to stop the piston at an appropriate position with a simple mechanism, and further improves the restartability by reducing the amount of burned gas remaining in the cylinder. Fuel consumption reduction and CO ₂ It is an object of the present invention to provide an engine starter capable of suppressing the emission amount.
[0013]
[Means for Solving the Problems]
According to the first aspect of the present invention, when the predetermined engine stop condition is satisfied, the fuel supply is automatically stopped to stop the engine, and when the restart condition is satisfied after the engine stop, the cylinder in the expansion stroke is burned. In the engine starter that restarts the engine, a throttle valve that is provided in a common intake passage upstream of the branching portion where the intake passage of each cylinder branches and adjusts the amount of intake air introduced into the cylinder of the engine, and the engine stop Throttle valve control means for adjusting the opening of the throttle valve during the engine stop operation period after the condition is satisfied, an ignition plug for generating a spark for combustion, and an ignition control means for controlling the ignition timing of the ignition plug; The throttle valve control means includes a cylinder that is in a compression stroke and a cylinder that is in an expansion stroke when the engine is stopped. To promote the scavenging of the cylinders as well as increase the resistance to movement of the point direction, after the formation the engine stop condition, quickly increases the degree of opening of the throttle valve, In addition, a predetermined amount before the last intake stroke of the cylinder that becomes the compression stroke when the engine is stopped starts so that the intake amount of the cylinder that becomes the compression stroke when the engine stops is smaller than the intake amount of the cylinder that becomes the expansion stroke when the engine stops. Close the throttle valve at the timing of The ignition control means retards the ignition timing immediately after the engine stop condition is satisfied.
[0014]
According to this configuration, when the engine is stopped after the engine stop operation period, in the cylinder in the compression stroke (hereinafter referred to as the compression stroke cylinder), the air in the cylinder is compressed as the piston approaches top dead center, and the pressure The engine reverses and the piston of the compression stroke cylinder is pushed back to the bottom dead center side, and the piston of the cylinder in the expansion stroke (hereinafter referred to as the expansion stroke cylinder) moves to the top dead center side. The air is compressed and the piston of the expansion stroke cylinder is pushed back to the bottom dead center side by the pressure, and the piston is vibrated to some extent by repeating such an operation and then stops. At this time, in the compression stroke cylinder and the expansion stroke cylinder, as the piston is closer to the top dead center, the force to push back the piston becomes larger. In particular, if the intake amount is increased before the engine is stopped as described above, it approaches the top dead center. Since the force to push back the piston increases when it hits, the piston stops within a predetermined range close to the middle of the stroke with a very high probability. The Further, by closing the throttle valve at a predetermined timing before the last intake stroke of the compression stroke cylinder is started so that the intake amount of the compression stroke cylinder is smaller than the intake amount of the expansion stroke cylinder, the piston is moved to the middle portion of the stroke. Even within the range close to, it will stop slightly closer to the bottom dead center. Also, Due to the retard of the ignition timing, the torque generated after the engine stop condition is satisfied can be reduced, and the torque fluctuation can be suppressed. Therefore, the variation in the rotational speed reduction characteristic when the engine is stopped is reduced, and the probability that the piston stops at an appropriate position can be further improved.
[0015]
By adjusting the stop position in this way, when starting the engine, it is possible to avoid that the amount of air for combustion in the expansion stroke cylinder becomes too small or that the energy due to combustion does not work well on the piston, which is good In addition, the engine is started by combustion in the expansion stroke cylinder.
[0016]
Furthermore, since the opening of the throttle valve is quickly increased after the engine stop condition is satisfied, scavenging of each cylinder is promoted, the ratio of fresh air at the time of restart is increased, and good combustion is facilitated. Is improved. In particular, a throttle valve is provided in the common intake passage upstream from the branch portion of the intake passage of each cylinder, and even if the engine is relatively prone to delay in the intake system, or the operating condition when the engine stop condition is satisfied However, even in an engine that is idling at a stoichiometric air-fuel ratio or an air-fuel ratio richer than that, scavenging performance is improved, and a high restartability improvement effect is obtained.
[0017]
Note that the term “quick” here means substantially simultaneously or immediately after, and particularly when there is a time difference between when the engine stop condition is satisfied and when the fuel supply is stopped, at least when the fuel supply is stopped, the throttle valve is opened. This means that the control to increase the degree has started. In the case of an engine provided with an ISC (idle speed control) valve that forms an intake passage that bypasses the common intake passage, the throttle valve includes this ISC valve.
[0021]
Claim 2 The present invention comprises at least a valve timing varying means for changing the opening / closing timing of the intake valve, and a valve timing control means for controlling the opening / closing timing of the intake valve by the valve timing varying means, and after the engine stop condition is established, Immediately, the valve timing control means delays the closing timing of the intake valve so that the effective compression ratio becomes a predetermined amount smaller than the effective expansion ratio, and the throttle valve control means increases the opening of the throttle valve. It is characterized by performing.
[0023]
Claim 2 According to the configuration In addition to retarding the ignition timing, reducing the effective compression ratio The torque generated after the engine stop condition is satisfied can be reduced to suppress torque fluctuation. Therefore, the variation in the rotational speed reduction characteristic when the engine is stopped is reduced, and the probability that the piston stops at an appropriate position can be improved.
[0024]
An EGR passage that recirculates exhaust through the common intake passage and the exhaust passage closer to each cylinder than the throttle valve; an EGR valve that is provided in the EGR passage and adjusts an exhaust gas recirculation amount; EGR valve control means for adjusting the opening of the EGR valve, and immediately after the engine stop condition is satisfied, the EGR valve control means closes the EGR valve and the throttle valve control means If configured to increase the opening, in an engine that performs EGR (exhaust gas recirculation), the exhaust gas is not recirculated during the automatic stop of the engine by idle stop, and scavenging in the cylinder is further promoted.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
1 and 2 show a schematic configuration of an engine according to an embodiment of the present invention. In these drawings, the main body of the engine 1 is composed of a cylinder head 2 a and a cylinder block 2. In this embodiment, the engine 1 is a four-cylinder four-cycle engine and includes four cylinders 3 (specifically, the first cylinder 3A, the second cylinder 3B, the third cylinder 3C, the fourth cylinder in order from the left in the state shown in FIG. 2). 3D). A piston 4 is inserted into each cylinder 3, and a combustion chamber 5 is formed above the piston 4. The piston 4 is connected to a crankshaft 6 via a connecting rod.
[0028]
A spark plug 7 is provided at the top of the combustion chamber 5 of each cylinder 3, and the tip of the plug faces the combustion chamber 5.
[0029]
Further, a fuel injection valve 8 that directly injects fuel into the combustion chamber 5 is provided at a side portion of the combustion chamber 5. The fuel injection valve 8 includes a needle valve and a solenoid (not shown). When a pulse signal is input, the fuel injection valve 8 is driven and opened for a time corresponding to the pulse width at the pulse input timing. It is comprised so that the quantity of fuel according to may be injected. The injection direction of the fuel injection valve 8 is set so as to inject fuel toward the vicinity of the spark plug 7. The fuel injection valve 8 is supplied with fuel via a fuel supply passage or the like by a fuel pump (not shown), and a fuel supply system so that a fuel pressure higher than the pressure in the combustion chamber during the compression stroke can be applied. Is configured.
[0030]
An intake port 9 and an exhaust port 10 are opened to the combustion chamber 5 of each cylinder 3, and an intake valve 11 and an exhaust valve 12 are provided in these ports 9 and 10. The intake valve 11 and the exhaust valve 12 are driven by a valve operating mechanism including camshafts 26, 27 and the like. As described later in detail, the opening / closing timings of the intake and exhaust valves of each cylinder are set so that each cylinder performs a combustion cycle with a predetermined phase difference.
[0031]
The opening / closing timing of the intake valve 11 and the exhaust valve 12 is variable by cam phase variable mechanisms 26a and 27a. The cam phase variable mechanisms 26a and 27a are conventionally known mechanisms that vary the rotational phase of the cam shafts 26 and 27 with respect to the rotational phase of the crankshaft, and function as valve timing variable means. 2, the camshaft 26 on the intake valve 11 side is provided with a cam phase variable mechanism 26a, and the camshaft 27 on the exhaust valve 12 side is provided with a cam phase variable mechanism 27a, which are controlled independently. ing. Therefore, the opening / closing timings of the intake valve 11 and the exhaust valve 12 can be varied back and forth generally independently by the cam phase variable mechanisms 26a and 27a.
[0032]
An intake passage 15 and an exhaust passage 16 are connected to the intake port 9 and the exhaust port 10. The intake passage 15 has a cylinder-specific branch intake passage 15a downstream of the surge tank 15b, and the downstream end of each branch intake passage 15a communicates with the intake port 9 of each cylinder. In the common intake passage 15c upstream of the surge tank 15b, a throttle valve 17 for adjusting the amount of intake air introduced into the cylinder 3 is provided. The opening degree of the throttle valve 17 is adjusted by a throttle valve actuator 18. An air flow sensor 20 for detecting the intake air amount is provided further upstream of the intake passage 15.
[0033]
Between the portion of the common intake passage 15 c downstream of the throttle valve 17 and the exhaust passage 16, an EGR passage 50 that communicates these is provided. The EGR passage 50 is provided with an EGR valve 51, and its opening degree is adjusted by an EGR valve actuator 52. When the EGR valve 51 is opened by the EGR valve actuator 52, a part of the exhaust gas passing through the exhaust passage 16 is recirculated to the common intake passage 15c via the EGR passage 50, and is supplied again to the cylinder 3 as intake air. . That is, EGR (exhaust gas recirculation) is performed.
[0034]
The crankshaft 6 is provided with a crank angle sensor that detects its rotation angle. In this embodiment, as will be described in detail later, crank angle signals that are out of phase with each other by a certain amount are output. Two crank angle sensors 21 and 22 are provided. Further, a cam angle sensor 23 is provided that can give a cylinder identification signal to the camshafts 26 and 27 by detecting their specific rotational positions. Further, a starter 28 that is a motor for starting the engine 1 is provided, and the driving force of the starter 28 is directly transmitted to the crankshaft 6 through a starter gear (not shown), whereby the engine 1 is started. It is configured as follows.
[0035]
In addition, as other detection elements necessary for controlling the engine 1, a water temperature sensor 24 for detecting the temperature of the engine cooling water, and an accelerator opening sensor 25 for detecting the accelerator opening (accelerator operation amount) (see FIG. 3). Etc. are equipped.
[0036]
FIG. 3 is a control block diagram of the engine 1, and shows a switch and a sensor for inputting a signal, a device and an actuator for outputting, etc., with an ECU (engine control unit) 30 as a center. Since this block diagram relates to idle stop control, other control-related parts are omitted.
[0037]
On the input side of the ECU 30, in addition to the air flow sensor 20, the crank angle sensors 21 and 22, the cam angle sensor 23, the water temperature sensor 24 and the accelerator opening sensor 25, sensors for performing I / S (idle stop) are provided. , A brake sensor 62 for detecting a brake depression depth, a vehicle speed sensor 63 for detecting a vehicle speed, an inhibitor switch 64 for detecting a shift lever position of an AT (automatic transmission), and a parking brake switch for detecting ON / OFF of a parking brake. 65, a winker switch 66 for detecting turn-on / off of the winker, an air-conditioner switch 67 for detecting ON / OFF of the air conditioner, and a brake for detecting brake negative pressure (negative pressure in a booster constituting a booster that supplements braking force) Each negative pressure sensor 68 is connected and each detection signal is input It is.
[0038]
Further, on the output side of the ECU 30, in addition to the ignition plug 7, the fuel injection valve 8, the throttle valve actuator 18, the EGR valve actuator 52, the cam phase variable mechanisms 26a and 27a, and the starter 28, an idle stop display lamp 71, an electric oil pump 72, an ATF switching valve 73 and a hill holder solenoid valve 74 are connected to output drive signals to the respective devices.
[0039]
The idle stop display lamp 71 is a lamp for indicating to the driver the implementation status of the I / S. As will be described in detail later, the engine is stopped by the I / S or the I / S is prohibited. This is a general term for lamps that indicate that the engine is restarted.
[0040]
The electric oil pump 72 is an electric oil pump that supplies hydraulic pressure to the AT while the engine is stopped by I / S. During normal operation, the clutch inside the AT operates with a mechanical oil pump (not shown) driven directly connected to the crankshaft 6 as a hydraulic pressure supply source. Therefore, when the engine is stopped by I / S, the hydraulic pressure is reduced and the clutch is released. This causes a time loss for re-engaging the clutch after restarting the engine, and the startability deteriorates. In order to prevent this, hydraulic pressure is separately supplied to the AT by the electric oil pump 72 while the engine is stopped.
[0041]
The ATF switching valve 73 is a switching valve that switches a passage of ATF (automatic transmission fluid) from the hydraulic supply source to the AT. During normal operation, the ATF is guided from the mechanical oil pump to the AT, and is switched from the electric oil pump 72 while the engine is stopped by I / S.
[0042]
The hill holder solenoid valve 74 is a solenoid valve for driving an unillustrated hill holder that blocks the brake oil supply passage. During normal operation, a booster linked to the engine operates to increase the brake hydraulic pressure. However, since the booster does not operate while the engine is stopped, the brake hydraulic pressure decreases and the braking force decreases. Therefore, for example, when idling stop is performed on a slope, the vehicle may move due to insufficient braking force. In order to prevent this, the hill holder is configured to maintain the brake hydraulic pressure in a high state by blocking the brake oil supply passage by the hill holder solenoid valve 74.
[0043]
The ECU 30 includes a throttle valve control means 31, a fuel injection valve control means 32, an ignition control means 33, an EGR valve control means 39, a cam phase control means 35, an idle stop control means 34, a display control means 36, and an AT control means 37. And hill holder control means 38.
[0044]
The throttle valve control means 31 calculates the required opening of the throttle valve 17 from the engine opening speed based on the accelerator opening information from the accelerator opening sensor 25 and the crank angular speed information from the crank angle sensors 21 and 22. The throttle valve actuator 18 is controlled.
[0045]
The fuel injection valve control means 32 and the ignition control means 33 determine the required fuel injection amount based on the intake air amount information from the air flow sensor 20 and the cooling water temperature information from the water temperature sensor 24 in addition to the accelerator opening information and engine speed information. And the injection timing and appropriate ignition timing are calculated and a control signal is output to the fuel injection valve 8 and the spark plug 7.
[0046]
The air-fuel ratio is determined by the intake air amount adjusted by the throttle valve control means 31 and the supplied fuel amount adjusted by the fuel injection valve control means 32. That is, the throttle valve control means 31 and the fuel injection valve control means 32 function as air-fuel ratio control means. During normal idle operation, the air-fuel ratio is set to the stoichiometric air-fuel ratio or richer than that. As will be described later, in order to suppress fluctuations in output torque during the engine stop operation period for idling stop, the air-fuel ratio is set to be leaner than that during idle operation, more preferably leaner than the stoichiometric air-fuel ratio. Is done.
[0047]
The EGR valve control means 39 outputs the required opening degree of the EGR valve 51 to the EGR valve actuator 52, and controls the EGR amount (the amount of exhaust gas recirculated). During normal operation, increasing the EGR amount suppresses the amount of oxygen in the intake air to lower the combustion temperature to reduce NOx emissions, or increase the in-cylinder temperature by exhaust when the engine is cold Control and so on. As will be described later, during the engine stop operation period for idling stop, control is performed to close the EGR valve 51 in order to promote scavenging in each cylinder 3.
[0048]
The cam phase control means 35 outputs the phase fluctuation signals of the cam shafts 26 and 27 with respect to the crankshaft 6 to the cam phase variable mechanisms 26a and 27a, and controls the opening / closing timings of the intake valve 11 and the exhaust valve 12. During normal operation, an optimal intake / exhaust valve opening / closing timing is set according to the engine speed, and control for obtaining a high output over a wide rotation range is performed. As will be described later, during the engine stop operation period for idling stop, control is performed to delay the closing timing of the intake valve 11 in order to suppress fluctuations in the output torque.
[0049]
The idle stop control unit 34 determines an execution condition of the I / S and provides necessary information for executing the I / S to each unit in the ECU 30.
[0050]
I / S execution conditions are classified into basic stop conditions, basic restart conditions, and I / S prohibition conditions. Each condition may be set as appropriate. For example, the brake depression depth obtained from the brake sensor 62 is not less than a predetermined value, the vehicle speed obtained from the vehicle speed sensor 63 is zero, and the AT shift lever position obtained from the inhibitor switch 64 Is the non-traveling range, the parking brake switch 65 signal is ON, the blinker switch 66 signal is OFF, and the air conditioner switch 67 is OFF, the basic stop condition is established.
[0051]
Further, for example, the brake depression depth is a predetermined value or less, the vehicle speed is a predetermined value or more, the shift lever position of the AT is the travel range, the signal of the turn signal switch 66 is ON, the air conditioner switch 67 is ON, or the brake negative pressure The basic restart condition is established when the brake negative pressure obtained from the sensor 68 is equal to or less than a predetermined value.
[0052]
For example, when the engine coolant temperature Tc is not more than a predetermined value (for example, Tc <60 ° C.), the battery monitor voltage is not more than a predetermined value, or the elapsed time since the previous restart is not more than a predetermined value, I / S prohibition The condition is met.
[0053]
When the basic stop condition is satisfied and the I / S prohibition condition is not satisfied, the engine stop condition is finally satisfied (in this specification, this is referred to as the satisfaction of the engine stop condition). The engine is automatically stopped. That is, the fuel injection from the fuel injection valve 8 is stopped and the ignition of the spark plug 7 is stopped.
[0054]
As the control when the engine is stopped, first, if the EGR valve 51 is open when the engine stop condition is satisfied, this is closed so that scavenging in the cylinder 3 is promoted. In order to suppress fluctuations in the output torque, the ignition timing is retarded (or the closing timing of the intake valve 11 may be delayed or the air-fuel ratio may be set to the lean side). Further, the throttle valve 17 is opened at a predetermined opening for a predetermined period to facilitate scavenging in the cylinder 3 after the fuel cut, and to make it easier for the piston 4 to stop at an appropriate position (range A in FIG. 4).
[0055]
If the basic restart condition or the I / S prohibition condition is satisfied while the engine is automatically stopped, the restart condition is finally satisfied (in this specification, this is referred to as the satisfaction of the restart condition). Made. That is, the fuel injection from the fuel injection valve 8 and the ignition of the spark plug 7 are returned.
[0056]
As the control at the time of restart, first, the cylinder which becomes the compression stroke when the engine is stopped (for the convenience of explanation, this is assumed to be the third cylinder 3C and will be referred to as the compression stroke cylinder 3C hereinafter) for the first time. By performing combustion and reversing the engine a little, the cylinder pressure is increased by the piston rise in the cylinder that is in the expansion stroke when the engine is stopped (also assumed to be the first cylinder 3A, hereinafter referred to as the expansion stroke cylinder 3A). Is increased, and then combustion is performed in the expansion stroke cylinder 3A.
[0057]
In the present embodiment, the initial combustion in the compression stroke cylinder 3C and the combustion in the expansion stroke cylinder 3A are performed, and the combustion air remains in the cylinder of the compression stroke cylinder 3C after the initial combustion, so that the compression stroke cylinder 3C Although the first restart control mode in which re-combustion is performed when the piston 4 reaches the top dead center after the piston 4 starts to rise, the initial combustion in the compression stroke cylinder 3C and the combustion in the expansion stroke cylinder 3A are performed. Combustion in the expansion stroke cylinder 3A and subsequent compression while assisting with the starter 28 without performing the first combustion in the compression stroke cylinder 3C without performing the second combustion control in the compression stroke cylinder 3C. A third restart control mode in which the engine is started by combustion in the stroke cylinder 3C is selectively executed according to the stop position of the piston 4.
[0058]
The display control means 36 performs ON / OFF control of the idle stop display lamp 71 according to the execution status of the I / S. The idle stop display lamp 71 includes an automatic stop lamp, an idle stop prohibition lamp, and a restart lamp that are not shown. When the engine is automatically stopped by I / S, the automatic stop lamp is turned on. When the I / S prohibition condition is satisfied, the idle stop prohibited lamp is turned on. When the engine is restarted, the restart lamp is turned on. In this way, the driver can recognize the idle stop control status.
[0059]
The AT control means 37 outputs a switching command signal to the ATF switching valve 73 when the pressure of the hydraulic oil supplied to the automatic transmission decreases due to execution of the idle stop, and supplies the hydraulic oil supply path. Is switched from the mechanical oil pump side (not shown) driven by the engine 1 to the electric oil pump 72 side, and an operation command signal for operating the electric oil pump 72 is output from the electric oil pump 72 to the automatic transmission. The hydraulic fluid is configured to supply a predetermined pressure.
[0060]
The hill holder control means 38 controls the hill holder by the hill holder solenoid valve 74 while the engine is stopped by the I / S.
[0061]
The stop position of the piston 4 when the engine is stopped due to idle stop is detected as follows by signals from the crank angle sensors 21 and 22. FIG. 5 is a pulse signal obtained by rotating the crankshaft 6, and shows a first crank angle signal CA 1 from the crank angle sensor 21 and a second crank angle signal CA 2 from the crank angle sensor 22. FIG. 5 (a) shows that during forward rotation (clockwise in the state of FIG. 1), and FIG. 5 (b) shows that during reverse rotation. During forward rotation of the engine, as shown in FIG. 5A, the second crank angle signal CA2 is generated with a phase delay of about a half pulse width with respect to the first crank angle signal CA1, so that the first crank angle signal CA1 The second crank angle signal CA2 is Low when rising, and the second crank angle signal CA2 is High when the first crank angle signal CA1 is falling. On the other hand, during reverse rotation of the engine, as shown in FIG. 5B, the second crank angle signal CA2 is generated with a phase advance of about a half pulse width with respect to the first crank angle signal CA1, so On the contrary, the second crank angle signal CA2 becomes High when the first crank angle signal CA1 rises, and the second crank angle signal CA2 becomes Low when the first crank angle signal CA1 falls. The ECU 30 detects this difference and counts the pulse signal while determining whether the crankshaft 6 is rotating forward or rotating backward. The counted value is stored as a CA counter value and is constantly updated while the engine 1 is operating. The state in which the increase or decrease in the CA counter value is lost is the stop of the engine 1, and the stop position of the piston 4 is detected based on the CA counter value at that time.
[0062]
FIG. 6 is an accumulation flowchart of CA counter values. After the start, in step S51, the second crank angle signal CA2 is Low when the first crank angle signal CA1 rises, or the second crank angle signal CA2 becomes High when the first crank angle signal CA1 falls. If it is YES, it indicates that the engine 1 is rotating forward, so that the process proceeds to step S52 and the measured pulse number is added to the CA counter value (CA counter up). If “NO” in the step S51, it indicates that the engine 1 is reversely rotated, so that the process proceeds to the step S53 and the number of pulses measured is subtracted from the CA counter value (CA counter down).
[0063]
Next, the operation of the apparatus of the present embodiment as described above will be described. In the engine 1 which is a four-cylinder four-cycle engine, each cylinder 3 performs a cycle composed of intake, compression, expansion, and exhaust strokes with a predetermined phase difference. As shown in FIG. However, the first cylinder 3A, the third cylinder 3C, the fourth cylinder 3D, and the second cylinder 3B are sequentially performed with a phase difference of 180 ° (180 ° CA) in crank angle.
[0064]
When the engine 1 is in a predetermined idling state that does not require the output of the engine 1 while the engine 1 is in operation, the idle stop is executed based on the determination of whether or not the engine stop condition is satisfied.
[0065]
FIG. 7 is an explanatory diagram up to engine stop in idling stop. FIG. 8 shows a schematic control flowchart of the ECU 30 at that time. After starting the control, signals from various sensors (see FIG. 3) are read (step S1). Next, based on the signal, it is determined whether or not the engine stop condition is satisfied (step S3). If NO, the process returns. If YES, the following series of controls for automatic engine stop (see FIG. 7) (control from the time t1 when the engine stop condition is satisfied until the engine stop). First, if the EGR valve 51 is opened at the time t1 when the engine stop condition is satisfied, a valve closing command is transmitted from the EGR valve control means 39 to the EGR valve actuator 52 to close the valve (step S4). By doing so, the exhaust gas is not recirculated into the cylinder 3, so that scavenging is promoted.
[0066]
Subsequently, in step S5, the ignition timing of the spark plug 7 is retarded by the ignition control means 33 (or the closing timing of the intake valve 11 may be delayed or the air-fuel ratio may be set to the lean side). As a result, the torque generated by the engine 1 is reduced and the torque fluctuation is suppressed, so that the variation in the rotational speed reduction characteristic when the engine is stopped is reduced, and the piston 4 stops at an appropriate position (range A in FIG. 4). Improve the probability of doing.
[0067]
Further, in the next step S6, the throttle valve 17 is opened by the throttle valve control means 31 (with a predetermined throttle opening as shown in FIG. 7). The opening of the throttle valve 17 is performed in order to increase the amount of intake air and promote scavenging in the cylinder 3. However, the throttle valve 17 of this embodiment is provided in the common intake passage 15c that is relatively distant from each cylinder 3, and the surge tank 15b is provided between each cylinder 3, so that the throttle valve 17 is opened. The response delay until the intake air amount actually increases from the valve is relatively long. Therefore, in this embodiment, the control in steps S4 to S6 in FIG. 8 is synchronized with the engine stop condition establishment time point t1 (started as soon as possible after the determination of YES in step S3). Thus, the throttle valve 17 is opened at the time t1 when the engine stop condition is established, which is the earliest timing in the engine stop operation period, and the effect of increasing the intake air amount due to the response delay is prevented as much as possible. Therefore, even if the engine is operated at idle at the stoichiometric air-fuel ratio or a richer air-fuel ratio at the time t1 when the engine stop condition is satisfied, scavenging of each cylinder is sufficiently performed by the increase in intake air made from such an early timing. Therefore, it is easy to obtain good combustion with sufficient oxygen when restarting after the engine is stopped. That is, restartability is improved.
[0068]
Subsequently, in step S7, it is determined whether or not the engine speed is in the fuel cut allowable speed range (650 ± 10 rpm). If “NO” here, the process waits until “YES”. When YES is determined in step S7, the fuel supply from the fuel injection valve 8 is stopped (fuel cut), and the ignition in the spark plug 7 is stopped (step S9). As described above, in this embodiment, the fuel cut allowable rotational speed range is provided, and the fuel cut is performed aiming at the time when the engine rotational speed is within the fuel cut allowable rotational speed range. For example, when the idle speed is feedback controlled to 650 ± 50 rpm, the fuel cut allowable speed range is set to 650 ± 10 rpm as described above. That is, when the engine is idling, the engine speed fluctuates in the range of 650 ± 50 rpm, and the fuel cut is performed aiming at the moment of entering the range of 650 ± 10 rpm. This is done to stop the piston 4 within a preferable range for restarting (range A in FIG. 4). When the fuel is cut in the fuel cut allowable rotation speed range, the piston 4 is within the preferable range. It has been confirmed that the probability of stopping at is high. If the engine speed at the time t1 when the engine stop condition is satisfied is in the fuel cut allowable speed range, the fuel is cut in synchronization with the time t1. However, if this is not the case, as shown in FIG. 7, the fuel cut is suspended until time t2 when the engine speed enters the fuel cut allowable speed range.
[0069]
After performing fuel cut at time t2 (engine speed N2), the throttle valve 17 is closed at time t3 when the engine speed has decreased to a predetermined speed N3 (N3 = 500 rpm in this embodiment) set in advance. Control is performed (steps S13 and S15). Thereby, the probability that the engine stop position is within a preferable range is increased by using the pressure of air in the cylinder 3.
[0070]
That is, during the period from time t1 to time t3, when the throttle valve 17 is opened to a predetermined opening, the intake negative pressure temporarily decreases (intake amount increases) with a slight time delay, and then the intake pressure negative Although the pressure increases (intake amount decreases), the predetermined rotation speed and the like are set in advance so that the period in which the intake negative pressure temporarily decreases substantially corresponds to the period of the intake stroke of the expansion stroke cylinder 3A. . As a result, compared with the case where the throttle valve 17 is not opened, and even when the throttle valve 17 is opened at the fuel cut time t2, the amount of air sucked into each cylinder 3 before the engine is stopped increases. However, in particular, the amount of intake air flowing into the expansion stroke cylinder 3A increases.
[0071]
When the engine is stopped, in the compression stroke cylinder 3C, as the piston 4 approaches top dead center, the air in the cylinder 3C is compressed and pressure is applied in a direction to push the piston 4 back, thereby causing the engine 1 to reverse. When the piston 4 of the compression stroke cylinder 3C is pushed back to the bottom dead center side, the piston 4 of the expansion stroke cylinder 3A moves to the top dead center side, and accordingly, the air in the cylinder 3A is compressed, The piston 4 of the expansion stroke cylinder 3A is pushed back toward the bottom dead center. In this way, the piston 4 is stopped after being vibrated to some extent. At this time, in the compression stroke and the expansion stroke, the force to push the piston 4 closer to the top dead center is larger, so the stop position of the piston 4 is the middle of the stroke. In many cases, the position is close to the portion (range A in FIG. 4).
[0072]
Further, if the intake air amount of the expansion stroke cylinder 3A is increased as compared with the compression stroke cylinder 3C by the control of the throttle valve 17 as described above, the piston 4 in the expansion stroke cylinder 3A is within the range close to the intermediate stroke portion. However, it often stops near the bottom dead center (range A2 in FIG. 4).
[0073]
In addition, sufficient scavenging is performed while the engine 1 is rotating several times due to inertia from the fuel cut time t2 until the engine 1 is completely stopped, and the inside of the cylinder is almost fresh even in the expansion stroke. Further, when the engine 1 is stopped, the pressure leaks immediately even in the compression stroke cylinder 3C. Therefore, after the engine is stopped, all cylinders are in a state where fresh air at substantially atmospheric pressure exists in the cylinder.
[0074]
The throttle valve 17 may not be closed until the engine is stopped. However, since the intake amount continues to be large until the engine is stopped, the push-down force of the piston 4 due to the compression of the intake is difficult to attenuate. In some cases, the number of vibrations increases and the swing back increases when the engine stops. Therefore, it is desirable to close the throttle valve 17 at a suitable time t3 as shown in the present embodiment.
[0075]
Subsequently, in order to determine whether or not the engine is stopped, the CA counter value (see FIG. 6) that is always counted is read (step S16). In the next step S17, it is determined whether or not the engine 1 has completely stopped from the degree of change of the CA counter value. If YES, the stop position of the piston 4 determined from the CA counter value is stored (step S19). And return.
[0076]
Next, restart of the engine 1 will be described. When the basic restart condition or the I / S prohibition condition is satisfied after the engine is stopped, it is determined that the restart condition is satisfied, and control for automatically restarting the engine 1 is performed. At this time, when the stop position of the piston 4 is within a predetermined range near the middle of the stroke in the expansion stroke cylinder 3A and within the range A1 (FIG. 4) near the top dead center, the first restart control mode is executed. Is done.
[0077]
FIG. 9 shows the stroke of each cylinder of the engine in the case of the first restart control mode and the combustion in each cylinder from the start of the start control ((1), (2), (3)... According to the order of combustion in the figure. And the direction of operation of the engine by each combustion is indicated by an arrow, and FIG. 10 shows the engine rotation speed, crank angle, and angular cylinder in the first restart control mode. The time variation of the in-cylinder pressure and the indicated torque is shown.
[0078]
As shown in these figures, in the case of the first restart control mode, first combustion is performed in the compression stroke cylinder 3C while the combustion air-fuel ratio is leaner than the stoichiometric air-fuel ratio ((1) in FIG. 9). The piston 4 of the compression stroke cylinder is pushed down to the bottom dead center side by the combustion pressure (part a in FIG. 10) due to the initial combustion, and the engine 1 is driven in the reverse direction. Accordingly, the expansion stroke cylinder 3A When the piston 4 approaches the top dead center, the air in the cylinder 3A is compressed and the in-cylinder pressure rises (portion b in FIG. 10). When the piston 4 of the expansion stroke cylinder 3A is sufficiently close to the top dead center, the cylinder 3A is ignited, and the fuel previously injected into the cylinder 3A is combusted ((2 in FIG. 9). ▼), the engine 1 is driven in the forward rotation direction by the combustion pressure (c portion in FIG. 10). Further, by injecting fuel to the compression stroke cylinder 3C at an appropriate timing, the second combustion in the cylinder 3C is performed near the top dead center of the compression stroke cylinder 3C ((3) in FIG. 9). ▼). The engine driving force is increased by the combustion pressure (d portion in FIG. 10).
[0079]
In this case, in the initial combustion of the compression stroke cylinder 3C, since the air-fuel ratio is lean, air remains in the cylinder 3C even after the initial combustion, so that the second combustion is possible. Since the fuel is injected and the compression is performed while the temperature in the compression stroke cylinder 3C is high due to the initial combustion, the second combustion in the cylinder 3C is performed by compression self-ignition.
[0080]
After the second combustion is performed in this way, after reaching the compression top dead center of the cylinder (fourth cylinder 3D) that reaches the compression stroke next to the cylinder 3C, each cylinder is sequentially controlled by normal control. Combustion is performed and restart is completed.
[0081]
When restarting when the stop position of the piston 4 is within a predetermined range near the middle of the stroke in the expansion stroke cylinder 3A and within the range A2 near the bottom dead center (see FIG. 4), the second restart control mode is used. Control is performed.
[0082]
As the control in the second restart control mode, first, in the compression stroke cylinder 3C, the initial combustion (combustion corresponding to (1) in FIG. 9) is performed while the combustion air-fuel ratio is substantially stoichiometric or richer. Is called. Then, the piston 4 of the compression stroke cylinder 3C is pushed down by the initial combustion and the engine 1 is driven in the reverse direction, and as a result, the piston 4 of the expansion stroke cylinder 3A approaches the top dead center, so that the air in the cylinder 3A is compressed. Thus, when the in-cylinder pressure rises and the piston of the expansion stroke cylinder 3A is sufficiently close to the top dead center, the cylinder 3A is ignited and the fuel previously injected into the cylinder 3A is combusted ( The fact that the engine 1 is driven in the forward rotation direction according to (2) in FIG. 9 is the same as the control in the first restart control mode. However, in the second restart control mode, combustion (combustion (3) in FIG. 9) is not performed when the compression stroke cylinder 3C passes the top dead center after the combustion of the expansion stroke cylinder 3A, and then the compression stroke is performed. The rotation of the engine is maintained by inertia until the compression top dead center of the cylinder (fourth cylinder 3D) that reaches is reached, and then the normal control is shifted to complete the restart.
[0083]
As described above, the first restart control mode and the second restart control mode are selectively used depending on the stop position of the piston 4, whereby the engine 1 is effectively restarted. This point will be described with reference to FIG.
[0084]
FIG. 11 shows the relationship between the piston position when the engine is stopped and the required air-fuel ratio in the first combustion (for reverse rotation) of the compression stroke cylinder 3C, the air amount of the compression stroke cylinder 3C, the air amount of the expansion stroke cylinder 3A, and the generation frequency. As shown in this figure, when the engine is stopped, the piston 4 of the expansion stroke cylinder 3A approaches the top dead center (the piston 4 of the compression stroke cylinder 3C approaches the bottom dead center). As the air amount in the stroke cylinder 3C increases, the air amount in the expansion stroke cylinder 3A increases as the piston 4 in the expansion stroke cylinder 3A approaches the bottom dead center (the piston 4 in the compression stroke cylinder 3C approaches the top dead center). The amount of air in the compression stroke cylinder 3C is reduced.
[0085]
In the initial combustion in the compression stroke cylinder 3C, the engine is reversely rotated to a predetermined position where the piston 4 of the compression stroke cylinder 3C is slightly before the bottom dead center (the piston 4 of the expansion stroke cylinder 3A is slightly before the top dead center). However, if the piston 4 of the compression stroke cylinder 3C is close to the top dead center, the amount of air in the compression stroke cylinder 3C is small and the reverse rotation to the predetermined position is performed. Since the required torque is relatively large, the required air-fuel ratio becomes rich. On the other hand, if the piston 4 of the compression stroke cylinder 3C is close to the bottom dead center, the amount of air in the compression stroke cylinder 3C is large, and the predetermined position Since the torque required for reverse rotation up to is relatively small, the required air-fuel ratio becomes lean.
[0086]
In the expansion stroke cylinder 3A, since the amount of air increases as the piston 4 is closer to the bottom dead center, more fuel can be burned.
[0087]
Accordingly, when the piston position of the expansion stroke cylinder 3A is within a predetermined range A2 near the bottom dead center from the middle portion (the piston position of the compression stroke cylinder 3C is near the top dead center) when the engine is stopped, the compression stroke cylinder 3C is in the initial combustion. The air-fuel ratio of the engine is made rich so as to meet the above requirements, and no combustion air remains after the first combustion, so the second combustion near the compression top dead center is not performed. A relatively large amount of fuel is injected, and after being compressed and then ignited and combusted, a relatively large torque is obtained, and further after the compression top dead center of the compression stroke cylinder 3C. The engine can be rotated until the compression top dead center of the next cylinder is exceeded, and restart can be achieved.
[0088]
On the other hand, when the engine is stopped, the piston position of the expansion stroke cylinder 3A is in the predetermined range A1 closer to the top dead center than the intermediate portion (the piston position of the compression stroke cylinder 3C is closer to the bottom dead center), compared to the case where the piston is in the range A2. Since the amount of air in the expansion stroke cylinder 3A is small, the torque obtained by the combustion in the expansion stroke is small. However, in the compression stroke cylinder 3C, the air-fuel ratio at the time of the first combustion is made lean corresponding to the above requirement, thereby Since the surplus air remaining after the first combustion is used and the second combustion near the compression top dead center is performed, the torque for driving in the engine forward direction is supplemented, and the combustion in the expansion stroke cylinder 3A Torque sufficient to achieve restart is obtained by both of the second combustion in the compression stroke cylinder 3C.
[0089]
By the way, in this embodiment, when the engine is stopped as described above, the compression stroke cylinder 3C is increased by increasing the opening amount of the throttle valve 17 for a predetermined period immediately after the engine stop condition is satisfied to increase the intake amount. Further, since the resistance to the movement of the piston 4 in the direction of the top dead center in the expansion stroke cylinder 3A is increased and the intake amount of the expansion stroke cylinder 3A is increased, the engine is stopped as shown in FIG. In most cases, the piston position in the expansion stroke cylinder 3A is within the predetermined range A near the middle of the stroke, and even within that, it is often within the range A2 near the bottom dead center. The restart is effectively performed by adjusting.
[0090]
That is, when the piston stop position is too close to the top dead center side of the expansion stroke cylinder 3A (the bottom dead center side of the compression stroke cylinder 3C) with respect to the range A, a sufficient amount of movement in the engine reverse rotation direction is taken. Since the amount of air in the expansion stroke cylinder 3A is reduced, the torque obtained by the combustion in the expansion stroke cylinder 3A is reduced, and the bottom dead center side of the expansion stroke cylinder 3A (compression stroke cylinder) If it is too close to 3C (top dead center side), the amount of air in the compression stroke cylinder 3C decreases, so that sufficient torque for engine reverse rotation cannot be obtained. On the other hand, if the piston stop position is within the above range A, the reverse rotation drive by the initial combustion in the compression stroke cylinder 3C is possible, and the combustion in the expansion stroke cylinder 3A is favorably performed and the combustion energy is reduced. In particular, if the piston stop position is in the range A2 near the bottom dead center of the expansion stroke cylinder 3A, a sufficiently large amount of air can be secured in the expansion stroke cylinder 3A. Combustion energy can be increased and startability can be improved.
[0091]
In rare cases, when the piston position when the engine is stopped is out of the above range A or when the engine is stopped, the in-cylinder temperature decreases, and the cooling water temperature Tc becomes lower than the predetermined temperature (Tc <60 ° C.). If this is the case, the third restart control mode is executed and the starter 28 assists the start.
[0092]
As mentioned above, although this invention was demonstrated according to embodiment, the specific structure of the apparatus of this invention is not limited to the said embodiment, A various change is possible within a claim. For example, specific values of the idle rotation speed (650 ± 50 rpm) and the fuel cut allowable rotation speed (650 ± 10 rpm) may be set as appropriate according to engine characteristics. Further, when idling up (control for increasing the idling engine speed when the engine temperature is relatively low) is performed, the fuel cut allowable engine speed may be changed accordingly.
[0093]
In the above embodiment, the closing of the EGR valve 51, the increase in the opening of the throttle valve 17 and the retard of the ignition timing (or the delay in the closing timing of the intake valve 11 or the leaning of the air-fuel ratio) Although they are performed in synchronism with each other, they should be started at least at the fuel cut time point t2 immediately after the engine stop condition time point t1, and within this range, slightly from the engine stop condition time point t1. It may be set with a delay of. However, the closer the opening timing of the throttle valve 17 is to the time t1 when the engine stop condition is established, the greater the effect of compensating for the delay of the intake system, and the greatest effect can be obtained when synchronized.
[0094]
In the above embodiment, in the engine stop operation period, instead of the control for retarding the ignition timing of the spark plug 7 by the ignition control means 33, the closing timing of the intake valve 11 is delayed or the air-fuel ratio is made lean. Good (see step S5 in FIG. 8). The selection may be optimized in accordance with the characteristics of the engine 1, but some of these controls may be performed together as necessary.
[0095]
In the above embodiment, when starting the engine when the piston position when the engine is stopped is within a predetermined range, the combustion is performed in the expansion stroke cylinder 3A after the initial combustion is performed in the compression stroke cylinder 3C and the engine is slightly reversed. However, the engine is not reversed due to the initial combustion in the compression stroke cylinder 3C, but the fuel is suddenly supplied to the expansion stroke cylinder 3A in the engine stopped state, and ignited after a predetermined time, thereby expanding the expansion stroke cylinder 3A. You may make it carry out combustion by first.
[0096]
Also in this case, if the piston stop position of the expansion stroke cylinder 3A is too close to the top dead center, the amount of air in the cylinder is small, so that sufficient energy cannot be obtained by combustion, and the stop position is at the bottom dead center. If the distance is too close, the stroke in which the energy from combustion acts on the piston 4 becomes extremely short, so that a sufficient driving torque cannot be obtained.
[0097]
Therefore, it is effective for improving the startability to increase the probability that the piston stop position is within the predetermined range A during the stroke by adjusting the intake air amount during the stop operation period as described above. By stopping within the close range A2, it is possible to increase the combustion energy by relatively increasing the amount of air in the cylinder, while avoiding that the stroke in which the energy due to combustion acts on the piston 4 becomes extremely short. It is advantageous for improving the performance.
[0098]
【The invention's effect】
As described above, according to the engine starting device of the present invention, when the predetermined engine stop condition is satisfied, the fuel supply is automatically stopped to stop the engine, and the expansion is performed when the restart condition is satisfied after the engine is stopped. In the engine starting device for injecting fuel to the cylinders in the stroke to perform ignition and combustion, and restarting the engine, the cylinder is provided in a common intake passage upstream of the branching portion where the intake passage of each cylinder branches, A throttle valve for adjusting the amount of intake air introduced into the cylinder of the engine; and throttle valve control means for adjusting the opening of the throttle valve during an engine stop operation period after the engine stop condition is satisfied, the throttle valve control means Is the resistance to movement of the piston toward the top dead center in the cylinder that is in the compression stroke and the cylinder that is in the expansion stroke when the engine is stopped. In order to facilitate the scavenging of each cylinder, the opening of the throttle valve is immediately increased after the engine stop condition is satisfied, so that the piston can be easily stopped at an appropriate position by a simple mechanism. At the same time, even if the intake system delay is relatively large, or when the engine stop condition is satisfied, the engine is in an idling operation with the stoichiometric air-fuel ratio or an air-fuel ratio richer than that. Even if it exists, scavenging is accelerated | stimulated and the quantity of the burnt gas which remains in a cylinder can be reduced, and restartability can be improved further. As a result, further reduction of fuel consumption and CO ₂ Emissions can be suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an engine equipped with a starting device according to an embodiment of the present invention.
FIG. 2 is a schematic plan view of the engine.
FIG. 3 is a schematic control block diagram of the engine.
FIG. 4 is an explanatory diagram illustrating setting of a range for selecting a restart control mode according to a piston position when the engine is stopped.
5A and 5B show crank angle signals from two crank angle sensors, where FIG. 5A is a signal when the engine is rotating forward, and FIG. 5B is a signal when the engine is rotating backward.
FIG. 6 is a flowchart showing a process for detecting a piston position when the engine is stopped.
FIG. 7 is an explanatory diagram showing changes in engine speed, throttle opening, intake pipe negative pressure, and cycles of each cylinder when the engine is stopped.
FIG. 8 is a control flowchart for automatically stopping the engine during idle stop.
FIG. 9 is an explanatory diagram showing the cycle and combustion operation of each cylinder when the engine is restarted.
FIG. 10 is an explanatory diagram showing changes in engine speed, crank angle, in-cylinder pressure of each cylinder, and indicated torque when the engine is restarted.
FIG. 11 is an explanatory diagram showing the relationship between the piston position when the engine is stopped and the required air-fuel ratio of the compression stroke cylinder, the air amount of the compression stroke cylinder, the air amount of the expansion stroke cylinder, and the generation frequency.
[Explanation of symbols]
1,1a engine
3 (3A, 3B, 3C, 3D) cylinder (1st cylinder, ..., 4th cylinder)
4 Piston
7 Spark plug
8 Fuel injection valve
11 Intake valve
12 Exhaust valve
15 Intake passage
15a Branch intake passage
15b Surge tank
15c Common intake passage
16 Exhaust passage
17 Throttle valve
26a, 27a Cam phase variable mechanism (valve timing variable means)
30 ECU
31 Throttle valve control means (air-fuel ratio control means)
32 Fuel injection valve control means (air-fuel ratio control means)
33 Ignition control means
35 Cam phase control means (valve timing control means)
39 EGR valve control means
50 EGR passage
51 EGR valve

Claims (3)

An engine that automatically stops fuel supply when a predetermined engine stop condition is satisfied, stops the engine, and restarts the engine by burning a cylinder in the expansion stroke when the restart condition is satisfied after the engine is stopped In the starter of
A throttle valve that is provided in a common intake passage upstream from a branch portion where the intake passage of each cylinder branches, and adjusts an intake amount introduced into the cylinder of the engine;
Throttle valve control means for adjusting the opening of the throttle valve during an engine stop operation period after the engine stop condition is satisfied;
A spark plug that generates sparks for combustion;
Ignition control means for controlling the ignition timing of the spark plug,
The throttle valve control means increases the resistance to movement of the piston in the direction of the top dead center in the cylinder that is in the compression stroke and the expansion stroke when the engine is stopped, and the engine stop condition in order to promote scavenging of each cylinder. When the engine is stopped , the throttle valve opening is quickly increased after the establishment, and the intake air amount of the cylinder that becomes the compression stroke when the engine is stopped is smaller than the intake amount of the cylinder that becomes the expansion stroke when the engine is stopped. The throttle valve is closed at a predetermined timing before the last intake stroke of the cylinder that becomes the compression stroke starts.
The engine starter characterized in that the ignition control means retards the ignition timing immediately after the engine stop condition is satisfied. Valve timing variable means for changing at least the opening and closing timing of the intake valve;
Valve timing control means for controlling the opening and closing timing of the intake valve by the valve timing variable means,
Immediately after the engine stop condition is satisfied, the valve timing control means delays the closing timing of the intake valve so that the effective compression ratio becomes a predetermined amount smaller than the effective expansion ratio, and the throttle valve control means 2. The engine starting device according to claim 1 , wherein the opening of the valve is increased . An EGR passage that recirculates exhaust gas by communicating the common intake passage and the exhaust passage closer to each cylinder than the throttle valve;
An EGR valve provided in the EGR passage for adjusting the exhaust gas recirculation amount;
EGR valve control means for adjusting the opening of the EGR valve,
3. The EGR valve control means closes the EGR valve and the throttle valve control means increases the opening of the throttle valve promptly after the engine stop condition is satisfied. The engine starting device as described.

Images