JP4307337B2 - Start control device for internal combustion engine - Google Patents

Description

  The present invention relates to a start control device for an internal combustion engine, and more particularly to a start control device for an internal combustion engine that can reliably start a gasoline internal combustion engine regardless of the state before the start.

  In a gasoline internal combustion engine using a spark plug, the air-fuel ratio of the air-fuel mixture is made richer than that during normal operation during normal startup to facilitate ignition during startup. When the fuel injection device is controlled by the electronic control device to control the air-fuel ratio, when the internal combustion engine is started, the fuel injection amount is increased as the temperature of the internal combustion engine is lower in order to stabilize the rotation of the internal combustion engine during the transition. As the temperature of the internal combustion engine rises, the fuel injection amount is reduced and corrected to the air-fuel ratio during normal operation (this is almost the stoichiometric air-fuel ratio).

  However, at the time of start-up, there is a case in which explosion does not occur even if cranking is performed due to various causes such as the air-fuel mixture becomes over-rich or the temperature is too low, and the start-up may not occur. At this time, a large amount of rich air-fuel mixture may enter the intake pipe or the cylinder and wet the spark plug. In this case, no matter how much cranking is performed, no sparking occurs and the engine cannot be started.

  Conventionally, in such cases, the spark plug was replaced with a new one, or the cylinder was scavenged by removing the spark plug and emptying the crank, but this was very time-consuming. It was.

  With respect to this problem, in Patent Document 1 (Japanese Patent Laid-Open No. 5-231213), when the key switch of the starter is turned on, the throttle opening is almost fully open, and the rotational speed of the internal combustion engine is below a predetermined value, that is, the engine is not started. Therefore, a start control device is proposed that switches to the scavenging mode on the condition that the fuel injection is stopped and cranked to scavenge the fuel in the cylinder.

  If the internal combustion engine starts during the cranking, confirm that the internal combustion engine continues to rotate for a predetermined time, cancel the scavenging mode, return to the normal mode, and start normal fuel injection. To do. At the same time, the throttle opening is throttled from a state close to full open to a state close to idling to prevent excessive increase in rotation. On the other hand, when the internal combustion engine does not start, it is determined that scavenging has been completed, the scavenging mode is canceled, the normal mode is restored, and normal starting is performed.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 5-321714), the same control as described above is performed by providing set values for the throttle opening, the rotation speed of the internal combustion engine, and the rotation time of the internal combustion engine.

  In Patent Documents 1 and 2, excess fuel remaining in the intake pipe and the cylinder can be removed, and the internal combustion engine can be easily started. However, since the throttle opening is almost fully open during the scavenging mode, the throttle opening is automatically returned to the normal opening when the internal combustion engine is started during the scavenging mode. As a result, the rotation speed of the internal combustion engine is prevented from rapidly increasing and the automatic clutch scooter or the like from running away.

  Patent Document 3 (Japanese Patent Laid-Open No. 6-146957) proposes a fuel control device for an internal combustion engine that can perform start-up control when the engine stalls in a gear-in state. If the engine stalls in a gear-in state, fuel may accumulate in the cylinder and the spark plug may get wet, making it impossible to start. Therefore, the fuel supply is stopped a predetermined number of times from the start of the start, and the inside of the cylinder is scavenged.

On the other hand, even if the internal combustion engine fails to start, it often starts well if it is left for a while and then the key switch is turned on again. This is thought to be because the fuel in the cylinder and the intake pipe gradually evaporates to dry the spark plug and allow sparking.
Further, when the operating internal combustion engine is stopped, if the internal combustion engine is still in a warm state, it is easy to start.
JP-A-5-231213 JP-A-5-321714 JP-A-6-146957

  In the above-described Patent Documents 1 to 3, in any case, when the start fails or the engine stalls, when the start succeeds thereafter, the normal mode is immediately returned. As described above, the normal mode means that the fuel injection amount is increased as the cooling water temperature of the internal combustion engine is lower in order to optimize the air-fuel ratio at the time of transition, and the fuel injection amount is decreased as the cooling water temperature is increased. It is control which correct | amends so that it may approach.

  However, if the pre-restart condition is over-rich, increasing the fuel injection amount immediately after the internal combustion engine has started will cause over-rich again, causing engine stall or exhaust gas in the exhaust gas. It is easy to cause problems such as an increase in toxic gas.

  The present invention has been conceived from the above facts, and at the time of starting, it is determined whether or not the state before starting is over-rich, and the internal combustion engine can be operated in one operation regardless of whether it is over-rich or not. It is an object of the present invention to provide a start control device that can start reliably and adjust the fuel to be supplied to the internal combustion engine after the start to enable an appropriate warm-up operation.

  In order to achieve the above object, a start control device for an internal combustion engine according to claim 1 of the present application includes a fuel injection device for injecting fuel to a predetermined location of the internal combustion engine, and a throttle for adjusting the amount of air fed into the cylinder of the internal combustion engine. A throttle position sensor for detecting the opening degree of the valve of the body, a spark plug provided in the cylinder, and a control device for controlling them; when starting the internal combustion engine, the control device If the fuel injection from the fuel injection device is stopped and the spark plug is ignited while the shaft rotates by a predetermined number of revolutions, and the internal combustion engine starts within the predetermined number of revolutions of the crankshaft, the fuel injection device The fuel supply amount after starting is less than the normal supply amount, and the internal combustion engine does not start within a predetermined number of revolutions of the crankshaft, Is characterized in that fuel injection device is controlled to provide a fuel supply amount at the time of normal start.

  The invention according to claim 2 of the present application is provided with a temperature sensor for detecting the temperature of the internal combustion engine, and the control device stops the fuel injection when the temperature of the internal combustion engine before starting exceeds a preset temperature. Instead, the control is performed so as to supply the fuel supply amount at the normal starting time.

  The invention according to claim 3 of the present application is characterized in that the start control device has a tachometer for detecting the rotation speed of the internal combustion engine, detects a state in which the tachometer exceeds a preset rotation speed, When the number is maintained for a preset time, it is determined that the internal combustion engine has been started.

  In the invention of claim 1, the internal combustion engine is started as follows. When starting a gasoline internal combustion engine, the fuel injection device stops fuel injection while the crankshaft rotates by a predetermined number of rotations. On the other hand, the spark plug ignites at a normal timing. When a gasoline-type internal combustion engine has a lot of gasoline remaining in the cylinder, such as when the engine fails to start due to over-richness, excess gasoline can be scavenged by cranking at this predetermined rotation.

  Since scavenging reduces the gasoline in the cylinder, the air-fuel ratio may become appropriate and the internal combustion engine may start during scavenging. In such a case, since it can be determined that the state before the start was over-rich, the amount of fuel supply after the start is less than the normal amount. As a result, over-richness can be prevented and stable internal combustion engine rotation can be obtained.

  If the internal combustion engine does not start even when the crankshaft rotates a predetermined amount, it is determined that there is no excess gasoline in the cylinder before starting, and the fuel is made to have the same rich air-fuel ratio as during normal starting. To start. The internal combustion engine is scavenged by a predetermined rotation of the crankshaft and does not leave excessive fuel, so it starts reliably. After the start, as in the case after the normal start, the fuel is injected so that the air / fuel ratio is richer than the stoichiometric air / fuel ratio, and after returning to the steady state, the fuel is returned to the stoichiometric air / fuel ratio.

  In the invention of claim 2, before starting the internal combustion engine, first, the temperature of the internal combustion engine is measured. If this temperature exceeds a preset temperature, it is determined that the internal combustion engine does not pass much time after it stops and is not in an overrich state but is easy to start, and the fuel is not stopped. During normal fuel injection, cranking is performed. On the other hand, when the temperature of the internal combustion engine is equal to or lower than a preset temperature, it is determined that there is a possibility of over-richness, and fuel injection is stopped and started according to claim 1.

  According to the third aspect of the present invention, whether or not the internal combustion engine has been started is determined based on whether or not the state in which the crankshaft rotates at a speed equal to or higher than a predetermined rotational speed lasts for a predetermined time.

  According to claim 1 of the present invention, it is possible to reliably start the fuel in any state, whether it is in a wet state due to fuel adhering to the cylinder before starting the internal combustion engine or in a dry state. Can be played. Further, when the start control device of the present invention is used, it is possible to prevent a state in which the inside of the cylinder becomes overrich or the spark plug gets wet.

  According to the second aspect, after the internal combustion engine is stopped, it is possible to change the starting method before and after returning to the cold state, and it is possible to start according to the situation without waste.

  According to the third aspect, whether or not the internal combustion engine has been started is determined based on whether or not a predetermined time has elapsed after the internal combustion engine has increased in rotational speed, so that a reliable determination can be made.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a configuration of a start control device for an internal combustion engine according to the present invention and its surroundings. The internal combustion engine body 1 includes one or more cylinders and a crankshaft that connects the cylinders. As the crankshaft rotates, air from the intake pipe 2 is sucked into the cylinder. The intake air amount is controlled by the opening degree of the throttle valve 3 a of the throttle body 3, and the opening degree of the throttle valve 3 a is detected by the throttle position sensor 4. The nozzle-like fuel injection device 5 injects gasoline into the air in the intake pipe 2 and is supplied into the cylinder as an air-fuel mixture. When the crankshaft rotates and the air-fuel mixture in the cylinder is compressed, the spark plug 6 sparks, the air-fuel mixture in the cylinder explodes to generate power, and the crankshaft rotates. The air-fuel mixture burned in the cylinder is exhausted from the cylinder by the rotation of the crankshaft, passes through the exhaust pipe 7 and is discharged to the outside air.

  The control device 8 comprises a microcomputer or the like, and controls ignition of the spark plug 6, control of fuel injected from the fuel injection device 5, detection of the opening of the throttle valve 3 a, and detection of the rotational speed of the internal combustion engine body 1 by the tachometer 9. The internal combustion engine temperature sensor 10 measures the temperature of the internal combustion engine. The internal combustion engine temperature sensor 10 may directly measure the temperature of the cylinder block or may measure the temperature of the cooling water.

  In the above configuration, the start control device of the present invention includes the control device 8, the throttle position sensor 4, the fuel injection device 5, the spark plug 6, the tachometer 9, and the internal combustion engine temperature sensor 10. Yes.

  FIG. 2 is a flowchart for explaining the start control method of the present invention. The method for starting an internal combustion engine by the start control device of the present invention will be described with reference to FIG.

  When the starter button of an automobile or the like is pressed, the crankshaft of the internal combustion engine is rotated by a cell motor (not shown) (S101). The control device 8 obtains temperature information of the internal combustion engine from the internal combustion engine temperature sensor 10 (S102). The internal combustion engine temperature sensor 10 may directly measure the temperature of the cylinder block, or may use the temperature of the cooling water. If this temperature is equal to or lower than a predetermined temperature, fuel injection from the fuel injection device 5 is stopped while the crankshaft rotates at a preset rotation speed. On the other hand, the spark plug 6 is ignited at a predetermined timing (S103). At this time, the throttle valve 3a has the same opening as that in the normal start. If a large amount of fuel remains in the cylinder, such as when the engine is stalled in a gear-in state, the inside of the cylinder can be scavenged by this cranking to eliminate excess fuel. During this scavenging, the fuel is gradually removed and the air-fuel ratio gradually decreases from the overrich state. When an appropriate air-fuel ratio is reached, the internal combustion engine starts.

  When the internal combustion engine is started, the rotation speed of the crankshaft increases to be higher than the rotation speed by the cell motor. Therefore, the control device 8 monitors the rotation speed of the crankshaft with the tachometer 9, and if the rotation speed exceeds the preset rotation speed for a preset time or longer, the internal combustion engine is turned on. It is determined that the engine has started (S104).

  If it is determined that the internal combustion engine has started, the control device 8 immediately starts to inject fuel from the fuel injection device 5, but considerable fuel still remains in the cylinder. In the case of normal startup, to make the fuel richer than the stoichiometric air-fuel ratio, a larger amount of fuel is supplied even after the startup. Sex occurs. Therefore, in the present invention, when the internal combustion engine is started, less fuel is supplied than in the case after the normal start (S105) to avoid engine stall. When the rotation of the internal combustion engine becomes stable and returns to a steady state, the normal injection amount is restored (S110), and the process ends.

  If the internal combustion engine does not start in S104, it is confirmed that the crankshaft has rotated by a preset number of rotations (S106), and the normal start is restored. That is, it is determined that the internal combustion engine does not start in S104 because there is no fuel in the cylinder. Since this state is the same as the state of starting a normal internal combustion engine, a normal start may be performed.

  Specifically, when it is confirmed that the crankshaft rotates a predetermined number of revolutions and the internal combustion engine does not start, fuel injection is performed from the fuel injection device 5 with a normal start pulse (S107). The fuel injection by the start pulse is to inject an amount of fuel that is richer than the air-fuel ratio (approximately the stoichiometric air-fuel ratio) during steady operation.

Since it is confirmed in S106 that there is no fuel in the cylinder, if the fuel is injected so that the air-fuel ratio becomes rich in S107, the internal combustion engine can be reliably started. When the start of the internal combustion engine is confirmed in the same manner as in S104 (S108), the increased amount of fuel is injected from the fuel injection device 5 so as to become richer than the air-fuel ratio in the steady state (S109). When the rotation of the internal combustion engine becomes stable, normal injection is performed with the stoichiometric air fuel ratio or an air fuel ratio close thereto (S110).
If the temperature of the internal combustion engine exceeds the predetermined temperature in S102, it is determined that the internal combustion engine is in a state where it is easy to start immediately after the internal combustion engine is stopped, and normal fuel injection is performed without stopping fuel injection. Do.

  Since the engine is started as described above, the internal combustion engine can be reliably started by a single operation, not only in the case of normal starting, but also in the case where excess fuel remains in the cylinder before starting.

  In the above-described embodiment, the temperature of the internal combustion engine is measured before starting, and the starting method is changed according to the temperature. However, it is also possible to start by omitting S102 regardless of the temperature of the internal combustion engine.

1 is a schematic diagram showing a configuration of an internal combustion engine start control device according to the present invention and its surroundings. It is a flowchart explaining the starting control method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine body 2 Intake pipe 3 Throttle body 3a Throttle valve 4 Throttle position sensor 5 Fuel injection device 6 Spark plug 7 Exhaust pipe 8 Control device 9 Tachometer 10 Temperature sensor

Claims (3)

  A fuel injection device that injects fuel into a predetermined location of the internal combustion engine, a throttle position sensor that detects the opening of a valve of a throttle body that adjusts the amount of air fed into the cylinder of the internal combustion engine, and an ignition provided in the cylinder A plug and a control device for controlling them; when starting the internal combustion engine, the control device stops fuel injection from the fuel injection device while the crankshaft rotates by a predetermined number of revolutions, and When the ignition plug is ignited and the internal combustion engine is started within a predetermined number of revolutions of the crankshaft, the fuel injection device supplies a fuel supply amount after the start less than a normal supply amount, When the internal combustion engine does not start within the rotational speed, the fuel injection device is controlled to supply the fuel supply amount at the normal start. Start-up control device for an internal combustion engine and butterflies.   A temperature sensor for detecting the temperature of the internal combustion engine is provided, and when the temperature of the internal combustion engine before the start exceeds a preset temperature, the fuel supply amount at the normal start without stopping the fuel injection 2. The start control device for an internal combustion engine according to claim 1, wherein control is performed so as to supply the engine.   The start control device has a tachometer that detects the number of revolutions of the internal combustion engine, detects a state in which the tachometer exceeds a preset number of revolutions, and the number of revolutions is maintained for a preset time. 3. The start control device for an internal combustion engine according to claim 1, wherein it is determined that the internal combustion engine has started.

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