JP6213486B2 - Engine starter - Google Patents

Description

  The present invention relates to an engine starter that starts an engine mounted on a vehicle.

  Conventionally, in a device that restarts an engine that has been automatically stopped when a predetermined stop condition is satisfied, if the scavenging while the engine is stopped is insufficient, the burned gas remaining in the cylinder may cause a restart. It is known that the combustion is hindered and the restartability is deteriorated. In order to solve this, for example, Patent Document 1 proposes an invention in which the opening of the throttle valve is increased after the engine stop condition is satisfied. As a result, scavenging of each cylinder is promoted and the fresh air ratio at the time of restarting increases, so that good combustion is facilitated and restartability can be improved.

JP 2004-293474 A

  However, the invention proposed in Patent Document 1 opens the throttle valve for scavenging, so that the in-cylinder pressure fluctuation when the engine is stopped increases, so the vibration felt by the driver increases. On the other hand, if the throttle opening is uniformly reduced to suppress such vibration, the scavenging effect is reduced. Thus, it has not been sufficiently studied to suppress vibration without reducing the effect of scavenging.

  The present invention has been made in view of the above, and an object of the present invention is to provide an engine starter capable of suppressing vibration without reducing the effect of scavenging.

  In order to solve the above-described problems and achieve the object, an engine starter according to the present invention is configured to scavenge each cylinder of the engine by opening a throttle valve of the engine during automatic stop of the engine mounted on the vehicle. In the engine starting device that restarts the engine by ignition start in response to a restart request, the time until the engine is completely stopped after the engine stop request is estimated, and the time until the engine is completely stopped In the case where the engine is long, control means for reducing the opening of the throttle valve during the automatic stop of the engine is provided compared to the case where the time until the complete stop is short.

  The engine starter according to the present invention suppresses the occurrence of vibration without reducing the effect of scavenging by reducing the throttle opening when the time for the engine to completely stop is longer than when it is short. Can do.

FIG. 1 is a block diagram showing the configuration of an engine starting device and its surroundings according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the estimated stop time and the throttle opening in the engine starter according to the embodiment of the present invention. FIG. 3 is a flowchart showing an example of processing by the engine starting device according to the embodiment of the present invention. 4 (a) and 4 (b) are timing charts showing the relationship between the engine speed and the throttle opening in the engine starting device according to another embodiment of the present invention. FIG. 5A is a diagram showing a valve timing diagram when the engine is stopped, and FIG. 5B is a diagram schematically showing the movement of the expansion stroke cylinder at the timing shown in FIG. 5A.

  Hereinafter, an embodiment of an engine starter according to the present invention will be described. In addition, this invention is not limited to the following embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

[First Embodiment]
The configuration of the engine starter according to the first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a vehicle equipped with an engine starter includes an engine 10 that is an electronically controlled internal combustion engine, a wheel speed sensor 60, a T / M rotation speed sensor 70, and an ECU (Engine Control Unit) 80. And. In FIG. 1, only the configuration related to the present invention is shown in the configuration of the vehicle, and the other configurations are not shown.

  Hereinafter, the configuration of the engine 10 will be described first. The engine 10 is, for example, a four-cylinder in-cylinder injection type, and as shown in FIG. 1, a cylinder block 11, a cylinder head 12, a cylinder bore 13, a piston 14, a crankcase 15, a crankshaft 16, and a connecting Rod 17.

  An injector 41 that injects fuel directly into the combustion chamber 18 is attached to the cylinder head 12. An injector 41 mounted on each cylinder is connected by a delivery pipe 42. Further, a high pressure pump 44 is connected to the delivery pipe 42 through a fuel supply pipe 43. Further, a spark plug 45 is attached to the cylinder head 12.

  The combustion chamber 18 of the engine 10 is composed of a cylinder block 11, a cylinder head 12, and a piston 14, and an upper central portion has a pent roof shape. Further, an intake port 19 and an exhaust port 20 are formed in an upper portion of the combustion chamber 18 so as to face each other. The lower ends of the intake valve 21 and the exhaust valve 22 are positioned with respect to the intake port 19 and the exhaust port 20, respectively.

  The intake valve 21 and the exhaust valve 22 are supported so as to be movable along the axial direction of the cylinder head 12. An intake camshaft 23 and an exhaust camshaft 24 are rotatably supported on the cylinder head 12. The intake cam 25 and the exhaust cam 26 are in contact with the upper ends of the intake valve 21 and the exhaust valve 22 via a roller rocker arm (not shown). The intake camshaft 23 and the exhaust camshaft 24 are provided with cam position sensors 33 and 34 for detecting the rotational phase.

  The engine 10 also has variable intake valve timing mechanisms (VVT) 27 and 28 that control the intake valve 21 and the exhaust valve 22 at the optimum opening / closing timing according to the operating state. . The intake / exhaust variable valve mechanisms 27 and 28 cause the hydraulic pressure from the oil control valves 31 and 32 to act on an advance chamber and a retard chamber (not shown) of the VVT controllers 29 and 30, so that the intake valve 21 and the exhaust valve The opening / closing timing of 22 can be advanced or retarded.

  A surge tank 36 is connected to the intake port 19 via an intake manifold 35. Further, an intake pipe 37 is connected to the surge tank 36, and an air cleaner 38 is attached to the air intake port of the intake pipe 37. An electronic throttle device 40 having a throttle valve 39 is provided on the downstream side of the air cleaner 38. On the other hand, an exhaust pipe 47 is connected to the exhaust port 20 via an exhaust manifold 46. The exhaust pipe 47 is equipped with catalyst devices 48 and 49.

  Further, the engine 10 is provided with a starter motor 50 that performs cranking. When an unillustrated pinion gear meshes with the ring gear when the engine is started, the rotational force is transmitted from the pinion gear to the ring gear to rotate the crankshaft 16. Can do.

  Here, the ECU 80 can control the injector 41, the spark plug 45, and the like. That is, the air flow sensor 52 and the intake air temperature sensor 53 mounted on the upstream side of the intake pipe 37 output the measured intake air amount and intake air temperature to the ECU 80, respectively. The intake pressure sensor 54 provided in the surge tank 36 outputs the measured intake pipe pressure (intake pipe negative pressure) to the ECU 80. Further, the throttle position sensor 55 and the accelerator position sensor 56 output the measured current throttle opening and current accelerator opening to the ECU 80, respectively. The crank angle sensor 57, the water temperature sensor 58, and the fuel pressure sensor 59 output the measured crank angle, engine cooling water temperature, and fuel pressure of each cylinder to the ECU 80, respectively.

  The ECU 80 determines each stroke of intake, compression, expansion (explosion), and exhaust in each cylinder based on the crank angle described above, and calculates the engine speed. Further, the ECU 80 drives the high-pressure pump 44 based on the above-described fuel pressure so that the fuel pressure becomes a predetermined pressure, and the above-described intake air amount, intake air temperature, intake pipe pressure, throttle opening, accelerator opening. The fuel injection amount, the injection timing, the ignition timing, and the like are determined based on the engine operating state such as the engine speed, the engine speed, and the engine cooling water temperature, and the injector 41 and the spark plug 45 are driven to execute the fuel injection and ignition.

  In the vehicle configured as described above, the ECU 80 as the control means automatically stops the engine 10 when stopped in an idle state, and starts when the engine 10 is automatically stopped. An engine restart function that automatically restarts according to the command.

  Hereinafter, configurations other than the engine 10 will be described. Wheel speed sensor 60 detects the rotational speed of each wheel of the vehicle and outputs the detection result to ECU 80. The T / M rotational speed sensor 70 detects the rotational speed of the input shaft in the transmission per unit time (hereinafter referred to as T / M input rotational speed), and outputs the detection result to the ECU 80. The “transmission state of the transmission or torque converter” used when estimating the engine stop time, which will be described later, is detected by the rotational speed of each wheel detected by the wheel speed sensor 60 and the T / M rotational speed sensor 70. It can be obtained from the T / M input rotation speed.

  The ECU 80 is physically configured using an electronic circuit mainly composed of a known microcomputer including an interface such as a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an input / output. The The function of the ECU 80 is to load an application program held in the ROM into the RAM and execute it by the CPU, thereby operating the controlled object under the control of the CPU and reading and writing data in the RAM and ROM. It is realized by doing.

  The ECU 80 receives the detection results of the various sensors described above, detects the operating state of the engine 10 based on the detection results, and controls the fuel injection amount and injection timing by the injector 41, the ignition timing by the spark plug 45, and the like. The engine starting device according to the present invention is realized by the function of the ECU 80.

  Here, as described above, if the scavenging while the engine is stopped is insufficient, combustion at the time of restart is hindered by the burned gas remaining in the cylinder, and the restartability is deteriorated. That is, as shown in FIGS. 5 (a) and 5 (b), immediately before the engine 10 is stopped, the compression process cylinder often loses the compression reaction force and reversely stops. At this time, the expansion stroke cylinder moves as indicated by 1-4 in FIG. As shown in FIG. 5B, since the exhaust valve opens before 2, the exhaust gas is sucked in the process of shifting to 3 if scavenging is not completed. Therefore, when restarting in the state of 4, since the exhaust gas has entered the cylinder, the startability is deteriorated.

  In the prior art (Patent Document 1), the throttle valve is opened when the engine is stopped for restarting by injecting and igniting the expansion stroke cylinder. When the rotational resistance of the engine is large, the throttle valve is closed than when the rotational resistance is small. The time is being advanced. The purpose of the prior art is to align the scavenging and stopping positions to a position suitable for starting, scavenging by opening the throttle valve, and closing the throttle valve immediately before stopping to control the position based on the balance of air volume. Is going. Here, scavenging is essential for restart by injection / ignition (that is, ignition start), and it is desirable to perform scavenging by opening the throttle valve when stopped as in the prior art. Will occur. The prior art focuses on the scavenging and cylinder stop positions and considers only idling stop, and thus does not focus on vibration suppression. However, it is necessary to achieve both scavenging and vibration suppression.

  Therefore, the engine starter according to the first embodiment of the present invention realized by the function of the ECU 80 described above opens the throttle valve 39 of the engine 10 while the engine 10 mounted on the vehicle is automatically stopped. The scavenging of each cylinder is executed, and the engine 10 is restarted by starting ignition in response to a restart request. Then, the engine starter estimates the time until the engine stops from the engine speed, the transmission state of the transmission, friction, etc., and adjusts the throttle opening according to the time until the stop. Specifically, the engine starter includes functions of a stop request determination unit, a stop time estimation unit, a throttle opening determination unit, a restart request determination unit, and a restart execution unit.

  The stop request determination unit (stop request determination means) determines whether or not the driver has requested to stop the engine 10. The stop request determination unit determines whether or not there is a stop request based on whether or not an automatic stop condition for the engine 10 is satisfied during operation of the vehicle. The automatic stop of the engine 10 is a so-called idle stop in which the engine 10 is stopped during idle operation. The automatic stop condition described above is, for example, a situation in which the vehicle speed value (hereinafter simply referred to as vehicle speed) is 0 km / h, the brake switch is ON, and the shift lever is in the neutral position (N) for a predetermined time. Etc. In such a case, the stop request determination unit determines that the vehicle is stopped by a red light and determines that the automatic stop condition is satisfied.

  The engine 10 may be stopped during deceleration of the vehicle. Examples of the automatic stop condition of the engine 10 during deceleration of the vehicle include a situation in which the vehicle speed is equal to or less than a certain speed, the engine speed is equal to or less than a certain rotation, the engine coolant temperature is equal to or less than a certain temperature, and the air conditioner is OFF. In such a case, the stop request determination unit determines that the vehicle is decelerating and determines that the automatic stop condition is satisfied.

  When the stop request determination unit determines that there is a request to stop the engine 10, the fuel injection by the injector 41 is stopped and the ignition by the spark plug 45 is stopped. Note that the vehicle speed, engine speed, and engine cooling water temperature used in the determination of the stop request described above are based on detection results of the wheel speed sensor 60, the crank angle sensor 57, and the water temperature sensor 58, respectively.

  The stop time estimation unit (stop time estimation means) estimates a time from when the engine 10 is requested to stop until the engine 10 is completely stopped (hereinafter referred to as an estimated stop time). Specifically, the stop time estimation unit can estimate the estimated stop time from the engine speed, the transmission state of the transmission or torque converter, and the friction (mechanical loss) of the engine 10 when the engine 10 is requested to stop. it can. The engine speed is calculated from the detection result of the crank angle sensor 57, and the transmission state of the transmission or torque converter is calculated from the detection results of the wheel speed sensor 60 and the T / M rotation speed sensor 70, for example. The friction of the engine 10 is estimated from, for example, the engine coolant temperature detected by the water temperature sensor 58 and the oil temperature of the transmission or torque converter detected by an oil temperature sensor (not shown). The complete stop of the engine 10 refers to a state where the engine speed is zero.

  The throttle opening determining unit (throttle opening determining means) determines the throttle opening during the automatic stop of the engine 10. The throttle opening determination unit determines an allowable throttle opening based on the estimated stop time estimated by the stop time estimation unit when the stop request determination unit determines that there is a request to stop the engine 10. Note that the throttle opening determined by the throttle opening determining unit is the throttle opening during the automatic stop of the engine 10, and when the engine 10 is restarted by the ignition start during the automatic stop or after the complete stop, the operation is performed. This refers to the throttle opening that makes it difficult for people to feel vibrations.

  In the ROM (not shown) of the ECU 80 described above, for example, as shown in FIG. 2, there is a map showing the relationship between the estimated stop time and the throttle opening obtained experimentally from the vibration requirements during the automatic stop of the engine 10. Stored in advance. The throttle opening degree determination unit calculates the throttle opening degree during the automatic stop of the engine 10 based on this map, for example. Note that the throttle opening may decrease linearly according to the estimated stop time as shown in FIG. 1, or may decrease in a non-linear manner (for example, a step shape).

  Here, when injection / ignition is performed on the expansion stroke cylinder when the engine is stopped, it is necessary to open the throttle valve 39 in order to increase the amount of oxygen in the cylinder (see FIG. 5). However, if the throttle valve 39 is opened uniformly, vibration when the engine is stopped increases. On the other hand, when the time from the fuel cut to the complete stop of the engine 10 is long, the process until the complete stop is long, and more scavenging can be performed, so that a sufficient scavenging is possible even with a small throttle opening. Become. Therefore, as shown in FIG. 2, when the estimated stop time is long, the throttle opening determining unit decreases the opening of the throttle valve 39 during the automatic stop of the engine 10 when the estimated stop time is short. With such a small throttle opening, vibrations can also be suppressed, so that both scavenging and vibration suppression can be achieved.

  After determining the allowable throttle opening as described above, the throttle opening determining unit opens the throttle valve 39 by the electronic throttle device 40 and sets the throttle opening to the determined allowable throttle opening (see FIG. 2). ). As described above, when the throttle valve 39 is opened during the automatic stop of the engine 10, the air in the intake pipe 37 flows into the surge tank 36 through the throttle valve 39, and the intake pipe pressure rises to become a positive pressure. . Therefore, the piston 14 that stops in the expansion stroke stops at a predetermined stop position in the expansion stroke, and each cylinder is scavenged by the inflow of air, so that the oxygen amount of the cylinder that stops in the expansion stroke is appropriately secured. Then, when the engine speed becomes zero, the throttle opening determination unit closes the throttle valve 39 by the electronic throttle device 40, whereby the engine 10 is completely stopped.

  The restart request determination unit (restart request determination means) determines whether or not there is a restart request for the engine 10 by the driver. The restart request determination unit determines whether or not there is a restart request based on whether or not the restart condition of the engine 10 is satisfied during the automatic stop of the vehicle. Here, examples of the restart condition include a situation where the brake switch is OFF and the accelerator pedal is ON. In such a case, the restart request determination unit determines that the driver has an intention to start, and determines that the restart condition is satisfied.

  The engine 10 stopped during deceleration of the vehicle may be restarted. Examples of the restart condition of the engine 10 during deceleration of the vehicle include a situation where the accelerator pedal is ON. In such a case, the restart request determination unit determines that the driver has an intention to start, and determines that the restart condition is satisfied.

  The restart execution unit (restart execution means) restarts the engine 10 that has been automatically stopped. The restart execution unit executes ignition start of the engine 10 when the restart request determination unit determines that there is a restart request for the engine 10. Specifically, the restart execution unit determines a cylinder stopped in the expansion stroke based on the detection result of the crank angle sensor 57 before restarting the engine 10, and determines the cylinder stopped in this expansion stroke. After a predetermined amount of fuel is injected into the combustion chamber 18 by the injector 41, the air-fuel mixture is ignited by the spark plug 45 to obtain an explosive force, drive the crankshaft 16 through the piston 14, and restart the engine 10. Start.

  The engine starter having the above configuration shows that the longer the time from when the engine 10 is automatically stopped until the engine 10 is completely stopped, the greater the number of cycles of the engine 10 and the higher the scavenging effect. The throttle opening for scavenging is reduced as the time until the engine 10 is completely stopped is increased. That is, as shown in FIG. 2, the engine starter decreases the throttle opening as the estimated stop time is longer, and increases the throttle opening as the estimated stop time is shorter. Thereby, the engine starter can suppress the occurrence of vibration without reducing the effect of scavenging.

  Hereinafter, an example of processing of the engine starter according to the first embodiment of the present invention will be described with reference to FIG.

  First, the stop request determination unit determines whether or not the driver has requested to stop the engine 10 (step S1). When it is determined by the stop request determination unit that there is a request to stop the engine 10 (Yes in step S1), the stop time estimation unit estimates an estimated stop time of the engine 10 (step S2). Next, the throttle opening determination unit determines the throttle opening based on the estimated stop time of the engine 10, and opens the throttle valve 39 so as to be the determined throttle opening (step S3).

  Next, the restart request determination unit determines whether or not there is a restart request for the engine 10 by the driver (step S4). When it is determined by the restart request determination unit that the driver has requested restart of the engine 10 (Yes in step S4), the restart execution unit executes ignition start of the engine 10 (step S5), and performs processing. finish. On the other hand, when the restart request determination unit determines that there is no restart request for the engine 10 by the driver (No in step S4), the engine starter waits until there is a restart request. The engine starter also ends the process when the stop request determination unit determines that there is no stop request for the engine 10 (No in step S1).

[Second Embodiment]
An engine starter according to a second embodiment of the present invention will be described with reference to FIG. Here, since the engine starter according to the second embodiment has the same configuration (FIG. 1) as that of the first embodiment except for the ECU 80, the illustration of the configuration is omitted.

  The engine starter according to the second embodiment is also realized by the function of the ECU 80 as in the first embodiment. Specifically, the ECU 80 according to the present embodiment includes a stop request determination unit, a throttle opening determination unit. The restart request determination unit and the restart execution unit are provided. That is, unlike the first embodiment, the present embodiment does not estimate the time until the engine 10 is completely stopped, and the throttle opening determination unit determines the throttle opening based on the engine speed.

  As shown in (1) of FIG. 4A and FIG. 4B, the engine starter according to the present embodiment has a small engine speed at the time of an engine stop request, such as in the case of an idle stop when the vehicle is stopped, When the time until the stop is short, the throttle valve 39 is greatly opened to stop. On the other hand, as shown in FIGS. 4A and 4B (2), the engine starter according to this embodiment is an engine at the time of an engine stop request, such as when the engine is stopped during traveling after acceleration. When the rotation speed is large and the time until stopping is long, the throttle valve 39 is opened small to stop.

  In the present embodiment, in the ROM (not shown) of the ECU 80 described above, for example, as shown in FIGS. 4 (a) and 4 (b), experimentally obtained from vibration requirements during the automatic stop of the engine 10, A map showing the relationship between the engine speed and the throttle opening is stored in advance. The throttle opening degree determination unit determines the throttle opening degree during the automatic stop of the engine 10 based on this map, for example.

  The engine starter according to the second embodiment having the above configuration can suppress the occurrence of vibration without reducing the scavenging effect, as in the first embodiment.

  The engine starting device according to the present invention has been specifically described above by the embodiments for carrying out the invention. However, the gist of the present invention is not limited to these descriptions, and is based on the description of the scope of claims. Must be interpreted widely. Needless to say, various changes and modifications based on these descriptions are also included in the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Engine 11 Cylinder block 12 Cylinder head 13 Cylinder bore 14 Piston 15 Crankcase 16 Crankshaft 17 Connecting rod 18 Combustion chamber 19 Intake port 20 Exhaust port 21 Intake valve 22 Exhaust valve 23 Intake camshaft 24 Exhaust camshaft 25 Intake cam 26 Exhaust cam 27, 28 Intake / exhaust variable valve mechanism 29, 30 VVT controller 31, 32 Oil control valve 33, 34 Cam position sensor 35 Intake manifold 36 Surge tank 37 Intake pipe 38 Air cleaner 39 Throttle valve 40 Electronic throttle device 41 Injector 42 Delivery pipe 43 Fuel supply pipe 44 High-pressure pump 45 Spark plug 46 Exhaust manifold 47 Exhaust pipe 48, 49 Catalyst Location 50 starter motor 52 the airflow sensor 53 intake air temperature sensor 54 intake air pressure sensor 55 throttle position sensor 56 accelerator position sensor 57 crank angle sensor 58 water temperature sensor 59 pressure sensor 60 the wheel speed sensors 70 T / M rotational speed sensor 80 ECU (control means)

Claims (1)

In an engine starter that performs scavenging of each cylinder of the engine by opening a throttle valve of the engine during automatic stop of an engine mounted on a vehicle, and restarts the engine by ignition start in response to a restart request ,
After the engine stop request, the time until the complete stop of the engine is estimated, and when the time until the complete stop is longer, the throttle during the automatic stop of the engine than when the time until the complete stop is shorter An engine starter comprising control means for reducing the opening of the valve.

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