JP4577616B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine for suppressing fuel from being ejected from a high-pressure fuel line at the time of a vehicle collision.

  In general, in an internal combustion engine, in particular, a direct injection internal combustion engine, each cylinder is provided with a fuel injection valve that directly injects fuel into a cylinder, and fuel pumped from a high-pressure fuel pump is accumulated in a delivery pipe, and the accumulated fuel Is supplied to each fuel injection valve. Each fuel injection valve is individually controlled to open and close by an electronic control unit. When the fuel injection valve is opened, high-pressure fuel equal to the pressure in the delivery pipe is injected and supplied to the in-cylinder combustion chamber.

  When this internal combustion engine is mounted on a vehicle, if the high-pressure fuel line is damaged due to a vehicle collision, the high-pressure fuel in the line may be ejected.

  As a countermeasure against this problem, Patent Document 1 includes an impact degree detection unit that detects an impact degree on the vehicle body. When the impact degree is larger than a set value, the fuel supply operation of the low-pressure fuel feed pump is stopped. A technique for fully opening a high-pressure pressure regulator provided downstream of a high-pressure line of a fuel system is disclosed. According to this, the fuel supply to the high-pressure fuel pump is stopped by the stop of the low-pressure fuel feed pump, while the high-pressure pressure regulator is fully opened, so that the fuel pressure in the high-pressure line is released to the fuel tank, and the fuel in the high-pressure line The pressure can be reduced to suppress fuel ejection.

Japanese Patent Laid-Open No. 7-139446

  However, in the technique disclosed in Patent Document 1, it is essential to install a high-pressure pressure regulator that can be instantaneously opened when a degree of impact greater than a set value is detected. The pressure regulator for high pressure is originally for regulating high pressure fuel during engine operation, and has a relatively large structure and high cost. Accordingly, a system that can reduce the pressure of the high-pressure fuel line when a collision is detected while omitting such components is desired.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for an internal combustion engine that can depressurize a high-pressure fuel line with a simple configuration when a vehicle collision is detected.

  In order to achieve the above object, one aspect of the present invention is a control device for an internal combustion engine including a fuel injection valve that injects fuel, and connects the high-pressure fuel pump, the high-pressure fuel pump, and the fuel injection valve. A high-pressure fuel line, a collision detection means for detecting a collision of a vehicle on which the internal combustion engine is mounted, and when a collision is detected by the collision detection means, the fuel supply from the high-pressure fuel pump is stopped, And a decompression control means for injecting fuel from the fuel injection valve.

  According to this aspect of the present invention, when a collision is detected by the collision detection means, the fuel supply from the high-pressure fuel pump is stopped and the fuel is injected from the fuel injection valve. The fuel pressure can be reduced, and the fuel injection from the inside to the outside when the high pressure fuel line is damaged can be suppressed. In particular, since a pressure reduction is performed using a fuel injection valve normally provided in an internal combustion engine without the need for a high-pressure pressure regulator as in Patent Document 1, it is possible to reduce the pressure of a high-pressure fuel line with a simple configuration. it can.

  Here, the internal combustion engine may have an ignition plug for igniting an air-fuel mixture in the cylinder. In this case, when the pressure reduction control means detects a collision by the collision detection means, the ignition plug It is preferable to stop the ignition due to the above.

  When the ignition by the ignition plug is also stopped in this manner, the internal combustion engine can be reliably stopped by reliably preventing ignition and combustion of the fuel injected for decompressing the high-pressure fuel line by the ignition plug.

  Further, when the engine is restarted after a collision is detected by the collision detection means, a restart control means for stopping the fuel injection from the fuel injection valve until a predetermined time elapses after the restart is started. It is preferable to provide.

  According to this preferred embodiment, since the fuel injection from the fuel injection valve is stopped until a predetermined time elapses from the start of restart, the engine is idled during this time, and the fuel injection valve injects the fuel when a collision is detected. The discharged fuel can be discharged from the cylinder. As a result, the mixture can be prevented from being overrich at the time of restarting, and the restarting can be suitably performed.

  The internal combustion engine may have a plurality of cylinders, the fuel injection valve may be provided for each cylinder, and the high-pressure fuel line may be connected to the fuel injection valve of each cylinder. However, when a collision is detected by the collision detection means, it is preferable that the fuel supply from the high-pressure fuel pump is stopped and fuel is simultaneously injected from the fuel injection valves of all cylinders.

  According to this preferred mode, fuel is simultaneously injected from the fuel injection valves of all cylinders when a collision is detected, so that the fuel pressure in the high-pressure fuel line can be instantaneously reduced at the highest speed. In addition, since fuel is shared and injected to each cylinder, the injection amount for each cylinder can be suppressed.

  Further, when the internal combustion engine has an ignition plug for igniting the air-fuel mixture in the cylinder, the restart control means also performs ignition by the ignition plug until a predetermined time elapses from the start of restart. It is preferable to stop.

  According to this preferred embodiment, the ignition is stopped together with the stop of the fuel injection even when the engine is restarted, so that it is reliably prevented that the fuel injected when the fuel pressure is reduced and remaining in the cylinder is ignited and burned by the spark plug. Thus, the internal combustion engine can be reliably maintained in an unburned state.

  According to the present invention, it is possible to provide a control device for an internal combustion engine that can reduce the pressure of a high-pressure fuel line with a simple configuration when a vehicle collision is detected.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 shows an internal combustion engine control apparatus according to this embodiment. As shown in the figure, the engine (internal combustion engine) 10 of this embodiment is a direct injection multi-cylinder spark ignition engine, more specifically a 4-cylinder gasoline engine. There is no particular restriction on the use. The engine 10 is mounted on a vehicle (not shown), and is particularly arranged in an engine room at the front of the vehicle.

  Each cylinder 11 of the engine 10 is provided with an injector (fuel injection valve) 12 for directly injecting fuel into the cylinder (combustion chamber) and an ignition plug 13 for igniting the air-fuel mixture in the cylinder. An electronic control unit (hereinafter referred to as ECU) 100 as a control means is provided. The ECU 100 controls the opening and closing of the injector 12 and also controls the ignition by the spark plug 13.

  Fuel is sent to the injector 12 by a fuel supply system 20. The fuel supply system 20 includes a fuel tank 21, a high-pressure fuel pump 30, and a high-pressure fuel line 23 that connects the high-pressure fuel pump 30 and the injector 12. The fuel in the fuel tank 21 is sent to the high pressure fuel pump 30 by the feed pump 24. The fuel pressure, that is, the feed pressure at this time is maintained at a relatively low constant value by the pressure regulator 25, and the value is, for example, about 0.3 MPa (3 atm). A fuel filter 26 is provided at the outlet of the feed pump 24.

  The high-pressure fuel line 23 includes a delivery pipe 27 commonly connected to the injectors 12 of each cylinder, and a high-pressure fuel pipe 28 that connects the high-pressure fuel pump 30 and the delivery pipe 27. In the high-pressure fuel line 23, high-pressure fuel corresponding to the fuel injection pressure from the injector 12 is accumulated, and the value is, for example, about 8 to 13 MPa (80 to 130 atm). In particular, the high-pressure fuel accumulated in the delivery pipe 27 is directly injected from the injector 12 into the combustion chamber when the injector 12 is opened. In the combustion chamber, an air-fuel mixture composed of the fuel and air sent from an intake passage (not shown) is generated. This air-fuel mixture is sparked by the spark plug 13 in the combustion chamber and drives the engine 10. The exhaust gas in the combustion chamber sequentially passes through the exhaust manifold 50 and the exhaust passage 51 and is discharged to the atmosphere, and is purified by the catalyst 52 provided in the exhaust passage 51.

  The high pressure fuel pump 30 pressurizes the low pressure fuel sent from the feed pump 24 and discharges it to the high pressure fuel pipe 28. The high-pressure fuel pump 24 is driven up and down by an inlet-side check valve 31 that mechanically opens and closes a suction passage for low-pressure fuel from the fuel tank 21 and a camshaft 32 driven by the engine, and pressurizes the fuel in the plunger chamber 33. A plunger 34, an outlet-side check valve 35 that mechanically opens and closes a discharge passage connected to the high-pressure fuel pipe 28, and an electromagnetic spill valve 36 that opens and closes an inlet portion of a return passage 37 extending from the plunger chamber 33 to the fuel tank 21. Is provided. When the plunger 34 is lowered, the low pressure fuel pushes the inlet side check valve 31 and flows into the plunger chamber 33. When the electromagnetic spill valve 36 is closed by the ECU 100 at a predetermined timing when the plunger is raised, the fuel in the plunger chamber 33 is pressurized by the subsequent raising of the plunger 34. The pressurized fuel pushes the outlet-side check valve 35 and is pumped to the high-pressure fuel pipe 28. As a result, the fuel pressure (fuel pressure) in the high-pressure fuel line 23 (particularly the delivery pipe 27) is increased, and high-pressure fuel is accumulated in the high-pressure fuel line 23. Backflow to the feed pump 24 side during fuel pumping is prevented by the inlet side check valve 31.

  As shown in FIG. 2, the electromagnetic spill valve 36 is closed and opened by the ECU 100 during the lift (lift) period of the plunger 34 (that is, the period from the bottom dead center BDC to the top dead center TDC). The electromagnetic spill valve 36 is open when on and closed when off. In the present embodiment, the opening timing Vo of the electromagnetic spill valve 36 is fixed at the top dead center TDC, and the closing timing Vc of the electromagnetic spill valve 36 is controlled by the ECU 100, so that the amount of fuel pumped from the high-pressure fuel pump 24 and therefore the delivery are increased. The fuel pressure in the pipe 27 is controlled. In the illustrated example, since the electromagnetic spill valve 36 is open during the period from the plunger bottom dead center BDC to the closing timing Vc of the electromagnetic spill valve 36, the fuel is not pressurized even when the plunger 34 is raised, and the return passage 37. Is returned to the fuel tank 21. During the period from the closing timing Vc of the electromagnetic spill valve 36 to the opening timing Vo (that is, the plunger top dead center TDC), the electromagnetic spill valve 36 is closed. The check valve 35 is pushed open and discharged to the high-pressure fuel pipe 28. The electromagnetic spill valve 36 is opened while the plunger 34 is lowered.

  The fuel pumping amount becomes maximum when the closing timing Vc of the electromagnetic spill valve 36 coincides with the bottom dead center BDC. This time is assumed to be pump duty D = 100%. As the closing timing Vc is delayed and approaches the opening timing Vo (top dead center TDC), that is, as the pump duty D decreases, the fuel pumping amount decreases. When the closing timing Vc of the electromagnetic spill valve 36 coincides with the opening timing Vo (top dead center TDC), that is, when the pump duty D is 0%, the electromagnetic spill valve 36 is left open without being closed, and the fuel pressure feed amount Becomes zero. At this time, the fuel pressure supply by the high-pressure fuel pump 24 is stopped.

  Returning to FIG. 1, the delivery pipe 27 is provided with a fuel pressure sensor 38 for detecting the fuel pressure therein, and the fuel pressure sensor 38 is connected to the ECU 100. The delivery pipe 27 is provided with a mechanical relief valve 39 as a safety valve. When the fuel pressure in the delivery pipe 27 rises abnormally, the fuel inside the delivery pipe 27 pushes the relief valve 39 open and returns to the fuel tank 21 via the return passage 40. This relief valve 39 is only for emergency use, and is not for controlling the pressure in the delivery pipe 27 during normal operation of the engine, and is different from the high-pressure pressure regulator described in Patent Document 1. In the present embodiment, the fuel pressure in the delivery pipe 27 is reduced by the fuel injection from the injector 12 except for when the relief valve 39 is abnormally opened during normal operation of the engine. The fuel pressure is increased by supplying fuel from the high-pressure fuel pump 30. The fuel pressure in the delivery pipe 27 is determined by the balance between the decrease and increase in the fuel pressure.

  In addition, an acceleration sensor 41 serving as a collision detection unit for detecting a collision of a vehicle on which the engine 10 is mounted is connected to the ECU 100. The acceleration sensor 41 is fixed at a predetermined position (for example, in the passenger compartment) in the vehicle body of the vehicle. The ECU 100 determines that a collision (for example, a frontal collision) has occurred when the acceleration G in a predetermined direction (for example, rearward of the vehicle) detected by the acceleration sensor 41 exceeds a predetermined value G1 stored in advance. The predetermined value G1 is set based on an experiment or the like as a minimum value of such a value that a certain amount of damage is expected to the vehicle or the engine, for example, when the airbag is activated. Specifically, it is about 2 to 3G. The acceleration sensor 41 may be shared as a collision detection sensor in the airbag control device.

  In addition, the engine 10 is provided with various sensors for detecting the operating state thereof, and these sensors are connected to the ECU 100. For example, a water temperature sensor for detecting the temperature of engine cooling water, an air flow meter for detecting the amount of intake air into the intake passage, a crank angle sensor for detecting the crank angle and thus the engine rotation speed, and an ignition operated by the driver There is a switch. The ECU 100 includes a so-called microcomputer including a CPU, a ROM, a RAM, and the like. The ECU 100 controls, for example, the fuel injection amount, the fuel injection timing, the ignition timing, and the fuel pressure in the delivery pipe 27 (the closing timing of the electromagnetic spill valve 36) based on the output signals of the sensors.

    Next, control (pressure reduction control) for reducing the fuel pressure in the high-pressure fuel line 23 when a vehicle collision is detected will be described with reference to FIG. The routine shown in FIG. 3 is repeatedly executed by the ECU 100 every predetermined time or every crank angle (for example, every several tens of milliseconds). Hereinafter, each step is represented by “S”.

  First, the ECU 100 detects a vehicle collision in S10. Specifically, it is determined whether or not the acceleration G detected by the acceleration sensor 41 exceeds a predetermined value G1. If no collision is detected, this routine is terminated. If a collision is detected, the pump duty is set to 0% in S12. Thereby, the fuel supply from the high-pressure fuel pump 30 to the delivery pipe 27 is stopped. At the same time, ignition by the spark plug 13 is stopped.

  Next, in S14, the ECU 100 opens the injector 12 of at least one cylinder and causes the injector 12 to execute fuel injection. In particular, in this embodiment, the injectors 12 of all cylinders are opened at the same time, and fuel injection is executed simultaneously for all cylinders. As a result, the fuel pressure in the high-pressure fuel line 23 including the delivery pipe 27 is instantaneously and most rapidly reduced, and the high-pressure fuel line 23 is damaged (for example, the high-pressure fuel pipe 28 and the delivery pipe 27 or the high-pressure fuel pump 30). Even when the connecting portion is loosened, the high-pressure fuel pipe 28 itself is cracked, etc., fuel injection from the high-pressure fuel line 23 to the outside is suppressed. At this time, since the ignition is already stopped in S12, the fuel is not burned even if fuel injection is performed, and the engine 10 is stopped reliably.

  Here, it is preferable that the opening time of the injector 12 is set such that fuel injection from the high-pressure fuel line 23 is sufficiently suppressed. In this embodiment, the opening time is set to an extremely short time equivalent to the opening time (several msec) in normal fuel injection, but even in this case, fuel injection is simultaneously performed from the injectors 12 of all cylinders. Depressurization can be performed quickly.

  Thereafter, in S16, the ECU 100 turns on the pressure reduction control flag and ends this routine.

  By the way, when damage caused by the collision is light, it is preferable that the engine is restarted to perform retreat. Therefore, in order to realize this, engine restart control executed after the pressure reduction control will be described with reference to FIG. The routine shown in FIG. 4 is also repeatedly executed by the ECU 100 every predetermined time or every crank angle (for example, every several tens of milliseconds).

  In S20, ECU 100 determines whether or not the starter is turned on by the driver based on the output of the ignition switch. If the starter is not turned on, this routine is terminated. If the starter is turned on, it is determined in S22 whether the pressure reduction control flag is turned on.

  When the decompression control flag is not on (that is, when it is off), since the previous engine stop is a normal stop that is not based on a vehicle collision, normal fuel injection control and ignition control are executed in S30, and the engine is operated as usual. Start.

  On the other hand, when the decompression control flag is on, it is determined in S24 whether or not the timer value TM built in the ECU 100 has passed a predetermined time TM1 stored in advance. This timer value TM is set to zero as an initial value, and is gradually increased from the time of first proceeding to S24. The predetermined time TM1 will be described later.

  Next, the ECU 100 stops fuel injection by the injector 12 and ignition by the spark plug 13 in S26. In particular, in the present embodiment, these are stopped for all cylinders. Therefore, the engine is not restarted in this state. This routine is completed.

  Thereafter, when the routine is repeatedly executed, the fuel injection and the ignition stop state are continued until the timer value TM passes the predetermined time TM1. During this time, therefore, the engine is idled by the starter. By this idling, the fuel injected during the pressure reduction control and remaining in the combustion chamber becomes an unburned mixture and is discharged to the exhaust system. If the fuel is not discharged due to such idling, the air-fuel mixture becomes overrich at the time of restart, which may cause misfire, knocking, initial rotation abnormal increase, and the like. If the fuel is discharged by idling as in the present embodiment, it takes a little more time than usual until the engine is restarted, but it can be suitably restarted in an almost normal mixture state.

  From this point of view, the predetermined time TM1 is set based on experiments or the like in advance so that the injected fuel at the time of pressure reduction control is sufficiently discharged from the combustion chamber by idling and does not give the driver a sense of incongruity. Specifically, for example, it is about 0.5 to 1 sec.

  It is expected that the unburned mixture exhausted to the exhaust system by idling is purified to some extent by the catalyst 52. This is because the engine restart after the collision is usually performed within a short time after the engine is stopped, and the catalyst is likely still in the active temperature range at the time of restart.

  In this way, when the timer value TM has passed the predetermined time TM1 in a certain control time while the idling operation is being continued, the pressure reduction control flag is turned off in S28, and normal fuel injection control and ignition control are performed in S30. Executed. This suitably restarts the engine.

  As described above in detail, according to the present embodiment, when the collision of the vehicle is detected, the fuel supply from the high-pressure fuel pump 30 is stopped and the fuel is injected from the injector 12. The fuel pressure of the fuel can be reduced, and when the high pressure fuel line 23 is damaged, fuel injection from the inside of the high pressure fuel line 23 to the outside is suppressed. In particular, it is not necessary to separately provide a high-pressure pressure regulator as in Patent Document 1, and the fuel pressure is reduced using the existing injector 12, so that the high-pressure fuel line 23 can be reduced in a simple configuration and at a low cost. .

  In particular, in the present embodiment, since the fuel is simultaneously injected from the injectors 12 of all the cylinders at the time of collision detection, the fuel pressure in the high-pressure fuel line 23 can be instantaneously reduced at the highest speed. Since fuel is divided and injected into each cylinder, the injection amount for each cylinder is suppressed, the time required for idling is reduced at the next restart, and the restart can be performed smoothly. Become.

  Furthermore, when the engine is restarted, the fuel injection from the injector 12 is stopped from when the restart is started (when the starter is turned on) until the predetermined time TM1 elapses. The engine can be idled to discharge the injected fuel from the combustion chamber. As a result, the mixture can be prevented from being overrich at the time of restarting, and the restarting can be suitably performed.

  Further, since the ignition is stopped at the time of fuel injection in the pressure reduction control, combustion can be reliably prevented and the engine can be stopped, and at the time of restart, the ignition is stopped together with the fuel injection stop. It is possible to reliably prevent combustion by the fuel remaining in the combustion chamber, and to reliably maintain the engine in an unburned state or an idling state.

  Various other embodiments of the present invention are conceivable. For example, the engine is a spark ignition type engine in the above embodiment, but may be a compression ignition type internal combustion engine, that is, a diesel engine instead. For example, the present invention can be suitably applied to a common rail diesel engine. Further, the engine may be not only a direct injection type but also an intake passage injection type that injects fuel into an intake passage (for example, an intake port). This is because this intake passage injection type engine may also have a high-pressure fuel line. Various configurations of the fuel supply system and the high-pressure fuel pump are conceivable.

  As can be understood from the above description, in the present embodiment, the decompression control unit and the restart control unit are configured by the ECU 100, and the collision detection unit is configured by the acceleration sensor 41 and the ECU 100.

  Embodiments of the present invention are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the spirit of the present invention defined by the claims are included in the present invention. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 is a system diagram showing a control device for an internal combustion engine according to the present embodiment. It is a timing chart which shows the opening / closing timing of the plunger lift and electromagnetic spill valve in a high-pressure fuel pump. It is a flowchart which shows the routine of pressure reduction control. It is a flowchart which shows the routine of restart control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Cylinder 12 Injector 13 Spark plug 20 Fuel supply system 23 High pressure fuel line 27 Delivery pipe 28 High pressure fuel piping 30 High pressure fuel pump 36 Electromagnetic spill valve 41 Acceleration sensor 100 Electronic control unit (ECU)

Claims (4)

A control device for an internal combustion engine including a fuel injection valve for injecting fuel,
A high-pressure fuel pump;
A high-pressure fuel line connecting the high-pressure fuel pump and the fuel injection valve;
A collision detection means for detecting a collision of a vehicle on which the internal combustion engine is mounted;
Pressure reduction control means for stopping fuel supply from the high-pressure fuel pump and injecting fuel from the fuel injection valve when a collision is detected by the collision detection means ,
The internal combustion engine has a plurality of cylinders, the fuel injection valves are provided for each cylinder, the high-pressure fuel line is connected to the fuel injection valves of the cylinders, and the pressure reduction control means collides with the collision detection means. When the engine is detected, the fuel supply from the high-pressure fuel pump is stopped, and the fuel is simultaneously injected from the fuel injection valves of all the cylinders . The internal combustion engine has an ignition plug for igniting the air-fuel mixture in the cylinder for each cylinder, and when the pressure reduction control means detects a collision by the collision detection means, the ignition plugs of all the cylinders are ignited. The control apparatus for an internal combustion engine according to claim 1, wherein the control is also stopped. Restart control means for stopping fuel injection from the fuel injection valves of all the cylinders until a predetermined time elapses from the start of restart at the time of engine restart after a collision is detected by the collision detection means; The control apparatus for an internal combustion engine according to claim 1, further comprising: The internal combustion engine has a spark plug for igniting the air-fuel mixture in the cylinder for each cylinder, and the restart control means uses the spark plugs of all cylinders until a predetermined time elapses from the start of restart. 4. The control apparatus for an internal combustion engine according to claim 3, wherein ignition is also stopped.

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