JP2018145854A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform fail-safe processing.SOLUTION: A control device of an internal combustion engine having a variable mechanism for changing a lifting amount of a plunger of a fuel pump, and a pressure regulation mechanism for regulating a pressure of the fuel of which the pressure is increased by the fuel pump, regulates a pressure of the fuel according to a discharged fuel pressure by controlling the pressure regulation mechanism while minimizing the lifting amount of the plunger by controlling the variable mechanism when a discharged fuel pressure of the fuel discharged from the fuel pump to a fuel injection valve is less than a prescribed value, on the other hand, changes the lifting amount of the plunger according to the discharged fuel pressure by controlling the variable mechanism while fixing the pressure to a pressure regulation level at the prescribed value by controlling the pressure regulation mechanism when the discharged fuel pressure is the prescribed value or more. Whether the variable mechanism or the pressure regulation mechanism is failed or not is determined on the basis of a condition of an actual fuel pressure Pa, so that the control of failed one is stopped, and the other normal one is controlled so that the actual fuel pressure Pa becomes a prescribed fuel pressure Ps not over an injection limit fuel pressure of the fuel injection valve even when a rotating speed of the internal combustion engine is increased, when the occurrence of the failure is determined.SELECTED DRAWING: Figure 22

Description

  The present invention relates to a control device for an internal combustion engine.

  The in-cylinder injection internal combustion engine is accompanied by a mechanical fuel pump that lifts the plunger against a biasing force of a spring pressing the tappet against the cam by a cam mechanism driven by the internal combustion engine. A mechanism including a variable mechanism for changing the lift amount of the plunger and a pressure adjusting mechanism for adjusting the pressure of the fuel boosted by the fuel pump is known (see, for example, Patent Document 1). Such a control device for an internal combustion engine adjusts the fuel by changing the lift amount of the plunger by the variable mechanism in the operation region where the required fuel pressure is relatively high, while the variable mechanism operates the plunger in the operation region where the required fuel pressure is relatively low. While keeping the lift amount to a minimum, the fuel is regulated by changing the rate at which the fuel boosted by the fuel pump by the pressure regulating mechanism returns to the low pressure side. Thereby, the frequency which raises the lift amount of a plunger is reduced, and the load of a cam mechanism is suppressed.

  The fuel pump is opened when the pressure of the fuel discharged from the fuel pump to the fuel injection valve, that is, the discharge fuel pressure exceeds a specified pressure which is the upper limit of control of the fuel pump, and returns the fuel to the low pressure side. A relief valve is provided so that the discharge fuel pressure does not exceed the injection limit fuel pressure.

Japanese Patent Laid-Open No. 2006-160822

  However, when the discharge flow rate of the fuel pump increases as the engine speed increases, the discharge fuel pressure for opening the relief valve becomes higher than the specified pressure. In addition, if the rate of fuel boosted by the fuel pump returns to the low pressure side due to a malfunction of the pressure adjustment mechanism, or if the plunger lift amount is fixed at the maximum due to a malfunction of the variable mechanism, the discharge flow rate of the fuel pump Increases more than normal. Therefore, when the engine speed increases with a failure in the pressure adjustment mechanism or variable mechanism, the discharge fuel pressure for opening the relief valve becomes higher than the specified pressure, exceeding the injection limit fuel pressure. There is a high possibility that

  SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for an internal combustion engine that diagnoses the presence or absence of a failure in a pressure adjusting mechanism and a variable mechanism and can perform fail-safe processing according to a failure mode.

  For this reason, in the control apparatus for an internal combustion engine according to the present invention, the fuel is lifted by the fuel injection valve that injects fuel into the cylinder and the cam mechanism that is driven by the internal combustion engine to lift the plunger against the urging force of the spring. The internal combustion engine having a fuel pump that boosts the pressure of the fuel and discharges it to the fuel injection valve, a variable mechanism that changes the lift amount of the plunger, and a pressure regulating mechanism that regulates the pressure boosted by the fuel pump. When the discharge fuel pressure, which is the pressure of the fuel discharged from the fuel pump to the fuel injection valve, is less than a predetermined value, the variable mechanism is controlled to minimize the lift amount of the plunger and the pressure adjustment mechanism is controlled to control the fuel. While the pressure is adjusted according to the discharge fuel pressure, when the discharge fuel pressure is equal to or higher than the predetermined value, the variable mechanism is controlled to control the pressure adjustment mechanism and the pressure adjustment level at the predetermined value is controlled. If there is a failure in the variable mechanism or pressure regulating mechanism based on the state of the discharged fuel pressure, and if it is determined that a failure has occurred, a failure has occurred. One control determined to be stopped is stopped, and the other control is controlled so that the discharge fuel pressure becomes a predetermined fuel pressure that does not exceed the injection limit fuel pressure of the fuel injection valve even if the rotational speed of the internal combustion engine increases. .

  According to the control device for an internal combustion engine of the present invention, it is possible to diagnose the presence / absence of a failure in the pressure adjusting mechanism and the variable mechanism and perform fail-safe processing according to the failure mode.

It is a schematic diagram showing an example of a fuel injection system. It is sectional drawing which shows the outline | summary of 1st Example of a variable mechanism. It is explanatory drawing of the method of increasing the lift amount of a plunger. It is explanatory drawing of the method to reduce the lift amount of a plunger. It is explanatory drawing of the method of hold | maintaining the lift amount of a plunger. It is explanatory drawing of an effect | action at the time of making the lift amount of a plunger the minimum. It is explanatory drawing of an effect | action at the time of maximizing the lift amount of a plunger. It is a perspective view which shows 2nd Example of a variable mechanism. It is a side view which shows 2nd Example of a variable mechanism. It is explanatory drawing of an effect | action at the time of making the lift amount of a plunger the minimum. It is explanatory drawing of an effect | action at the time of maximizing the lift amount of a plunger. It is a block diagram which shows an example of the internal structure of a fuel pump control apparatus. It is explanatory drawing of the normal fuel pressure adjustment range by a pressure regulation mechanism and a variable mechanism. It is a flowchart which shows the normal fuel pressure control process of a high pressure fuel pump. It is explanatory drawing which shows an example of the method of setting a predetermined value. It is explanatory drawing of the fuel pressure adjustment by the variable mechanism at the time of the fully-closed failure of a pressure regulation mechanism, (a) When normal, (b) The fuel pressure adjustable range at the time of failure, (c) Fail fuel pressure adjustment range. It is explanatory drawing of the restriction | limiting characteristic of the discharge fuel pressure by a relief valve. It is explanatory drawing of the fuel pressure adjustment by the pressure regulation mechanism at the time of the maximum lift failure of a variable mechanism, (a) When normal, (b) Fuel pressure adjustable range at the time of failure, (c) Fail fuel pressure adjustment range. It is explanatory drawing of the fuel pressure adjustment by the variable mechanism at the time of the fully open failure of a pressure regulation mechanism, (a) When normal, (b) Fuel pressure adjustable range at the time of failure, (c) Fail fuel pressure adjustment range. It is explanatory drawing of the fuel pressure adjustment by the pressure regulation mechanism at the time of the minimum lift failure of a variable mechanism, (a) At the time of normality, (b) The fuel pressure adjustable range at the time of failure, (c) Fail fuel pressure adjustment range. It is a flowchart which shows 1st Embodiment of a failure diagnosis and a fail safe process. It is a flowchart which shows 1st Embodiment of a failure diagnosis and a fail safe process. It is a flowchart which shows 2nd Embodiment of failure diagnosis and fail safe processing.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 shows an example of a fuel injection system that directly injects fuel into a cylinder of an internal combustion engine, and the control device according to the first embodiment of the present invention is applied to the fuel injection system.

  An electronically controlled fuel injection valve 200 that directly injects fuel into each cylinder of the cylinder block 120 is attached to the cylinder head 110 of the internal combustion engine 100 mounted on the automobile. In response to an operation signal from the outside, the fuel injection valve 200 lifts a plunger biased in the valve closing direction by a spring, thereby injecting fuel into the cylinder from the nozzle hole at the tip. Here, as the internal combustion engine 100, for example, an in-line four-cylinder in-cylinder gasoline engine or a diesel engine can be used.

  A feed pump (low-pressure fuel pump) 400 that sucks fuel from the bottom and pressure-feeds the fuel tank 300 for storing fuel is attached. A fuel discharge port 410 of the feed pump 400 is connected to a fuel supply port 600A of a high-pressure fuel pump 600 that boosts the fuel to a predetermined pressure via a low-pressure fuel pipe 500. The fuel discharge port 600B of the high-pressure fuel pump 600 communicates with the fuel supply port 210 of each fuel injection valve 200 via a high-pressure fuel pipe 520 that branches into a plurality of portions on the way.

  Therefore, the fuel stored in the fuel tank 300 is sucked up by the feed pump 400 and supplied to the high-pressure fuel pump 600 through the low-pressure fuel pipe 500. The fuel supplied to the high-pressure fuel pump 600 is boosted to a predetermined pressure and then supplied to each fuel injection valve 200 through the high-pressure fuel pipe 520. The high-pressure fuel pump 600 is an example of a fuel pump.

Here, an example of the high-pressure fuel pump 600 will be described.
Inside the pump body 610, a low-pressure damper 610A that smoothes the pulsation of fuel supplied from the feed pump 400, a cylinder 610B in which a plunger 620 is reciprocably fitted, and a pressurizing chamber 610C that pressurizes the fuel. Are formed respectively. An intake valve having a spring 630A and a valve body 630B that opens only in a direction in which fuel flows from the low pressure damper 610A to the pressurizing chamber 610C, in the low pressure fuel passage 610D that communicates the low pressure damper 610A and the pressurizing chamber 610C. 630 is disposed.

  Further, the suction valve 630 is provided with a solenoid actuator 640 that forcibly opens the valve body 630B against the urging force of the spring 630A. The high-pressure fuel passage 610E that connects the pressurizing chamber 610C and the fuel discharge port 600B has a spring 650A and a valve body 650B that opens only in the direction in which the fuel flows from the pressurization chamber 610C to the fuel discharge port 600B. A discharge valve 650 is provided.

  At the lower end of the plunger 620, that is, at the end opposite to the pressurizing chamber 610C, the rotational motion of the cam mechanism 660 driven by the rotational force of the crankshaft, camshaft, etc. of the internal combustion engine 100 is converted into linear motion. A tappet 670 is attached. The tappet 670 is pressed against the cam 660A by a spring 680 such as a compression coil spring so as to come into contact with the cam 660A of the cam mechanism 660.

  Therefore, when the cam 660A of the cam mechanism 660 rotates, the rotational motion is converted into a linear motion by the tappet 670, and the plunger 620 reciprocates. When the plunger 620 descends, the volume of the pressurizing chamber 610C increases, so that the fuel pressure (hereinafter referred to as “fuel pressure”) in the pressurizing chamber 610C decreases, the intake valve 630 opens, and pressure is applied from the low pressure damper 610A. Fuel flows into the chamber 610C. On the other hand, when the plunger 620 is raised, the volume of the pressurizing chamber 610C is decreased, so that the fuel pressure in the pressurizing chamber 610C is increased, the intake valve 630 is closed, and the discharge valve 650 is opened. When the discharge valve 650 is opened, the fuel in the pressurizing chamber 610C is discharged from the fuel discharge port 600B through the high-pressure fuel passage 610E.

  If the intake valve 630 is opened when the plunger 620 is lifted, the fuel that has flowed into the pressure chamber 610C when the plunger 620 is lowered passes through the low pressure fuel passage 610D to the low pressure damper 610A (low pressure side). Is returned. Therefore, by changing the valve closing timing of the intake valve 630 when the plunger 620 is raised by the solenoid actuator 640, the ratio of the fuel returned to the low pressure side and the fuel to be boosted is changed. The fuel pressure of the fuel discharged to the fuel injection valve 200 (hereinafter referred to as “discharge fuel pressure”) can be adjusted. The closing timing of the suction valve 630 is from a fully open state where the solenoid actuator 640 is always open to a fully closed state where the solenoid actuator 640 is not energized and the valve closing timing is not changed. Can be changed. Here, the suction valve 630 and the solenoid actuator 640 are cited as examples of the pressure adjustment mechanism 645. Therefore, the closing timing of the suction valve 630 changed by the solenoid actuator 640 is an example of the pressure regulation level by the pressure regulation mechanism 645.

  Further, the low pressure damper 610A and the high pressure fuel passage 610E downstream of the discharge valve 650 are opened only in the direction in which fuel flows out from the high pressure fuel passage 610E to the low pressure damper 610A, and a relief valve having a spring 690A and a valve body 690B. 690 communicates.

  When the discharge fuel pressure exceeds a specified pressure that is the upper limit of control of the high-pressure fuel pump 600, the relief valve 690 moves and opens the valve body 690B against the biasing force of the spring 690A, and the relief valve 690 opens from the high-pressure fuel passage 610E to the low-pressure damper. Drain the fuel to 610A. For this reason, discharge fuel pressure is restrict | limited to below regulation pressure, for example, the fuel injection valve 200, piping, etc. which are located in the downstream can be protected.

  Further, a variable mechanism 700 that changes the lift amount of the plunger 620 is attached to the high-pressure fuel pump 600.

FIG. 2 shows a first embodiment of the variable mechanism 700.
The plunger 620 includes a first structure 622 that faces the pressurizing chamber 610C, a second structure 624 that sits on the tappet 670, and a base end (lower end) that can be relatively displaced in the axial direction. It is divided into two. The first structure body 622 is provided with a hydraulic pressure, which is an example of hydraulic oil, and moves the first structure body 622 away from the second structure body 624 in a direction away from the first structure body 622. A working chamber 622A is formed. Further, in the second structure body 624, a ring-shaped second working chamber that receives supply of hydraulic pressure and moves the first structure body 622 in the direction of approaching the second structure body 624. 624A is formed. Here, the first working chamber 622A and the second working chamber 624A are formed in a shape such that the pressure receiving areas of the first structure body 622 are equal.

  Therefore, as shown in FIG. 3, when hydraulic pressure is supplied to the first working chamber 622A, the first structure 622 moves away from the second structure 624, and the lift amount of the plunger 620 is increased. Can be increased. In addition, as shown in FIG. 4, when hydraulic pressure is supplied to the second working chamber 624A, the first structure 622 moves toward the second structure 624 and the lift amount of the plunger 620 is increased. Can be reduced. In order to maintain the lift amount of the plunger 620, as shown in FIG. 5, when the hydraulic pressure is supplied to the first working chamber 622A and the second working chamber 624A, the plunger 620 is moved upward and downward in the drawing. The force to move to the balance can be balanced and the position can be maintained.

  Therefore, when the cam mechanism 660 is driven while the lift amount of the plunger 620 is minimized, as shown in FIG. 6, the stroke amount of the plunger 620 is minimized, the pushing amount for pushing the spring 680 is minimized, and mechanical friction is obtained. Can be reduced. As the cam mechanism 660 is driven, as shown in FIG. 7, the lift amount of the plunger 620 is maximized at the end of the fuel discharge stroke (top dead center), and the plunger at the start of the fuel discharge stroke (bottom dead center). When the lift amount of 620 is minimized, the stroke amount of the plunger 620 is maximized. And since the stroke amount of the plunger 620 becomes the maximum, the discharge fuel pressure can be maximized. In addition, by changing the lift amount of the plunger 620 at the top dead center between the minimum and the maximum, the discharge amount of the fuel discharged from the high-pressure fuel pump 600 can be changed, and the discharge fuel pressure can be arbitrarily changed. .

8 and 9 show a second embodiment of the variable mechanism 700. FIG.
The variable mechanism 700 includes a drive shaft 710 that rotates in conjunction with the crankshaft of the internal combustion engine 100, a peristaltic cam 720 that is rotatably mounted on the outer periphery of the drive shaft 710, and an eccentric that is fixed to the outer periphery of the drive shaft 710. A cam 730, a ring-shaped link 740 that is externally fitted to the eccentric cam 730, a control shaft 750 that is disposed substantially parallel to the drive shaft 710, and a control cam that is eccentrically fixed to the outer periphery of the control shaft 750 760, a rocker arm 770 that is fitted to the control cam 760 so as to be relatively rotatable and has one end connected to the ring-shaped link 740, and a rod-like link 780 that connects the other end of the rocker arm 770 and the swing cam 720. Have. When the control shaft 750 is rotated via the gear train 792 by a motor 790 such as a brushless motor, the rocking center of the rocker arm 770 changes according to the rotation angle. When the rocking center of the rocker arm 770 changes, the lift amount of the plunger 620 reciprocated by the rocking cam 720 can be changed.

  Therefore, when the drive shaft 710 is driven while the lift amount of the plunger 620 is minimized, as shown in FIG. 10, the stroke amount of the plunger 620 is minimized, the pushing amount for pushing the spring 680 is minimized, and mechanical friction is obtained. Can be reduced. When the drive shaft 710 is driven while the lift amount of the plunger 620 is maximized, the stroke amount of the plunger 620 is maximized as shown in FIG. 11, and the discharge fuel pressure can be maximized. Note that the discharge fuel pressure can be arbitrarily changed by changing the lift amount of the plunger 620 from the minimum to the maximum.

  The variable mechanism 700 is not limited to the first embodiment described with reference to FIGS. 2 to 7 and the second embodiment described with reference to FIGS. 8 to 11, and the lift amount of the plunger 620 of the high-pressure fuel pump 600 can be changed. Any configuration may be used as long as it is present.

Next, a control system of the high pressure fuel pump 600 will be described.
A fuel pressure sensor 800 that detects an actual value (actual fuel pressure) Pa of the discharged fuel pressure is attached to the high-pressure fuel pipe 520. The output signal of the fuel pressure sensor 800 is input to a fuel pump control device 810 having a built-in microcomputer. In addition, the fuel pump control device 810 can be configured to read the target fuel pressure Pt, the rotational speed Ne of the internal combustion engine 100, and the load Q, for example, via an in-vehicle network 820 such as a CAN (Controller Area Network). The engine control device 830 that electronically controls 100 is communicably connected. For example, the engine control device 830 obtains the target fuel pressure Pt according to the rotational speed Ne and the load Q of the internal combustion engine 100, and transmits this to the fuel pump control device 810. The fuel pump control device 810 is an example of the control device.

  As the load Q of the internal combustion engine 100, for example, a state quantity closely related to the torque of the internal combustion engine 100 such as an intake flow rate, a suction negative pressure, a boost pressure, and an accelerator opening can be used. Further, the fuel pump control device 810 can read the rotation speed Ne and the load Q from a known sensor instead of reading the rotation speed Ne and the load Q from the engine control device 830.

  As shown in FIG. 12, the fuel pump control device 810 and the engine control device 830 include a processor A such as a CPU (Central Processing Unit), a non-volatile memory B such as a flash ROM (Read Only Memory), and a RAM (Random Access). A volatile memory C such as a memory), an input / output circuit D serving as an interface with an external device, and a bus E that connects these to each other so that they can communicate with each other.

  The fuel pump control device 810 obtains the operation amounts of the solenoid actuator 640 and the variable mechanism 700 based on the actual fuel pressure Pa, the target fuel pressure Pt, the rotational speed Ne, and the load Q by a control program stored in the nonvolatile memory B, respectively. . The fuel pump control device 810 outputs an operation signal corresponding to the operation amount to the solenoid actuator 640 and the variable mechanism 700, thereby electronically controlling them according to the operating state of the internal combustion engine 100.

  Specifically, as shown in FIG. 13, when the actual fuel pressure Pa is less than a predetermined value, the fuel pump control device 810 fixes the lift amount of the plunger 620 to the minimum by the variable mechanism 700 (minimum lift). Fixed), the discharge fuel pressure is adjusted by changing the valve closing timing of the intake valve 630 by the solenoid actuator 640, thereby reducing the mechanical friction of the spring 680. On the other hand, when the actual fuel pressure Pa is greater than or equal to a predetermined value, the fuel pump control device 810 uses the solenoid actuator 640 to fix the closing timing of the intake valve 630 to the intermediate valve closing timing when the actual fuel pressure Pa is a predetermined value. However, the discharge fuel pressure is adjusted by changing the lift amount of the plunger 620 from the minimum to the maximum range by the variable mechanism 700 according to the actual fuel pressure Pa (fixed at the intermediate opening). The predetermined value is a threshold value for determining whether or not the variable mechanism 700 needs to increase the lift amount of the plunger 620.

  In FIG. 13, when the lift amount of the plunger 620 is minimum and the intake valve 630 is fully open, the actual fuel pressure Pa becomes the minimum fuel pressure Pmin that is the control lower limit of the high-pressure fuel pump 600, while the plunger 620 When the lift amount is the maximum and the closing timing of the intake valve 630 is the intermediate closing timing, the actual fuel pressure Pa becomes the maximum fuel pressure Pmax that is the upper limit of control of the high-pressure fuel pump 600. Therefore, when the pressure adjusting mechanism 645 and the variable mechanism 700 are normal, the normal fuel pressure adjustment range, which is the adjustment range of the discharge fuel pressure by the pressure adjusting mechanism 645, is equal to or higher than the minimum fuel pressure Pmin and less than a predetermined value. The normal fuel pressure adjustment range, which is the fuel pressure adjustment range, is not less than a predetermined value and not more than the maximum fuel pressure Pmax.

[Normal fuel pressure control processing]
FIG. 14 shows the normal fuel pressure control of the high-pressure fuel pump 600 that is repeatedly executed at predetermined time intervals by the processor A of the fuel pump control device 810 when the fuel pump control device 810 is started in conjunction with the ignition operation. An example of processing is shown.

  In step S1 (abbreviated as “S1” in the figure, the same applies hereinafter), it is determined whether or not the actual fuel pressure Pa read from the fuel pressure sensor 800 by the processor A of the fuel pump control device 810 has not reached the target fuel pressure. Then, it is determined whether or not the actual fuel pressure Pa has converged to the target fuel pressure Pt by feedback control. That is, the processor A of the fuel pump control device 810 determines whether or not the actual fuel pressure Pa has decreased to the target fuel pressure Pt when the target fuel pressure Pt decreases, or whether the actual fuel pressure Pa has decreased to the target fuel pressure Pt. Determine if it has risen. When the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa has not reached the target fuel pressure Pt (YES), the process proceeds to step S2. On the other hand, when the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa has reached the target fuel pressure Pt (NO), the normal fuel pressure control process of the high-pressure fuel pump 600 is performed to maintain the state. End.

  In step S2, the processor A of the fuel pump control device 810 determines whether or not the actual fuel pressure Pa is equal to or greater than a predetermined value. As described above, the predetermined value is a threshold for determining whether or not it is necessary to increase the lift amount of the plunger 620 by the variable mechanism 700, and is set as follows. If the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa is equal to or higher than the predetermined value (YES), the process proceeds to step S3. On the other hand, if the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa is less than the predetermined value (NO), the process proceeds to step S6.

(Preset value setting method)
The actual fuel pressure Pa of the fuel discharged from the high-pressure fuel pump 600 varies depending on the rotational speed Ne and the load Q of the internal combustion engine 100 when the opening degree of the intake valve 630 and the lift amount of the plunger 620 are constant. That is, the plunger 620 of the high-pressure fuel pump 600 reciprocates at a cycle proportional to the rotational speed Ne of the internal combustion engine 100 to boost the fuel, and the fuel boosted by the reciprocation of the plunger 620 is a load on the internal combustion engine 100. Consumed according to Q. For this reason, whether or not the lift amount needs to be changed by the variable mechanism 700 varies depending on the rotational speed Ne and the load Q of the internal combustion engine 100.

  Therefore, through experiments and the like, as shown in FIG. 15, a predetermined value that defines the boundary between the fixed region and the operating region of the variable mechanism 700, which changes according to the rotational speed and load of the internal combustion engine 100, is obtained and mapped. And stored in the nonvolatile memory B. Then, the processor A of the fuel pump control device 810 refers to this map to obtain a predetermined value corresponding to the rotational speed Ne and the load Q of the internal combustion engine 100. Note that the predetermined value shown in FIG. 21 is merely an example, and does not necessarily change with the illustrated characteristics.

  In step S3, the processor A of the fuel pump control device 810 determines whether or not the actual fuel pressure Pa is near the target fuel pressure Pt, that is, the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa (| Pt−Pa |). Is less than or equal to the mechanism selection threshold value ΔPb. The mechanism selection threshold value ΔPb indicates which of the fuel pressure adjustment mechanisms including the pressure adjustment mechanism 645 and the variable mechanism 700 performs fuel pressure adjustment according to whether or not the deviation between the actual fuel pressure Pa and the target fuel pressure Pt is very small. This is a threshold value for discrimination. If the processor A of the fuel pump control device 810 determines that the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is equal to or less than the mechanism selection threshold value ΔPb (YES), the process proceeds to step S4. . On the other hand, when the processor A of the fuel pump control device 810 determines that the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is larger than the mechanism selection threshold value ΔPb (NO), the process proceeds to step S5. .

  In step S <b> 4, the processor A of the fuel pump control device 810 performs fuel pressure adjustment by the pressure adjustment mechanism 645. That is, the processor A of the fuel pump control device 810 supplies the fuel pressure to the solenoid actuator 640 according to the deviation between the target fuel pressure Pt and the actual fuel pressure Pa in order to finely adjust the fuel pressure by adjusting the closing timing of the intake valve 630. Change the duty ratio of PWM (Pulse Width Modulation). Thereby, the discharge fuel pressure of the high-pressure fuel pump 600 is feedback-controlled toward the target fuel pressure Pt.

  In step S <b> 5, the processor A of the fuel pump control device 810 changes the operation amount of the variable mechanism 700 in accordance with the deviation between the target fuel pressure Pt and the actual fuel pressure Pa in order to adjust the fuel pressure by the variable mechanism 700. Thereby, the discharge fuel pressure of the high-pressure fuel pump 600 is feedback-controlled toward the target fuel pressure Pt.

  In step S <b> 6, the processor A of the fuel pump control device 810 determines whether the lift amount of the plunger 620 is minimized by the variable mechanism 700, for example, via the control state of the variable mechanism 700. If the processor A of the fuel pump control device 810 determines that the lift amount of the plunger 620 is the minimum (YES), the process proceeds to step S7. On the other hand, if the processor A of the fuel pump control device 810 determines that the lift amount of the plunger 620 is not the minimum (NO), the process proceeds to step S8.

  In step S <b> 7, the processor A of the fuel pump control device 810 performs fuel pressure adjustment by the pressure adjustment mechanism 645. In other words, the processor A of the fuel pump control device 810 supplies a duty ratio to the solenoid actuator 640 in accordance with the deviation between the target fuel pressure Pt and the actual fuel pressure Pa in order to adjust the fuel pressure by adjusting the closing timing of the intake valve 630. Feedback control. Thereby, the discharge fuel pressure of the high-pressure fuel pump 600 is feedback-controlled toward the target fuel pressure Pt.

  In step S8, the processor A of the fuel pump control device 810 changes the operation amount of the variable mechanism 700 so as to minimize the lift amount of the plunger 620. When the lift amount of the plunger 620 is minimized, the stroke of the plunger 620 lifted by the cam 660A of the cam mechanism 660 is reduced, and mechanical friction due to the biasing force of the spring 680 can be reduced.

[Fuel pressure adjustment range when the fuel pressure adjustment mechanism fails]
Here, the range in which the fuel pressure can be adjusted by the high-pressure fuel pump 600 when the pressure regulating mechanism 645 or the variable mechanism 700 fails will be described with reference to FIGS.

  FIG. 16B shows the normal fuel pressure adjustment range of the high-pressure fuel pump 600 when the pressure regulating mechanism 645 and the variable mechanism 700 are normal. FIG. 16B shows the high-pressure fuel when the pressure regulating mechanism 645 is fully closed. The fuel pressure adjustable range of the pump 600 is shown. In the fully closed failure (failure mode 1) of the pressure adjusting mechanism 645, the suction valve 630 opens due to a decrease in the fuel pressure in the pressurizing chamber 610C when the plunger 620 descends. The valve closing timing at which the intake valve 630 closes when the valve rises cannot be changed, and the intake valve 630 closes when the plunger 620 changes from descending to ascending. The range in which the fuel pressure can be adjusted by the high-pressure fuel pump 600 when the pressure regulating mechanism 645 is fully closed is the range in which the fuel pressure can be adjusted by the variable mechanism 700.

  When the pressure regulating mechanism 645 is fully closed, the fuel that flows into the pressurizing chamber 610C when the plunger 620 descends hardly returns to the low pressure side via the suction valve 630, and almost all the fuel that flows into the pressurizing chamber 610C is lost. It will be in the state (all discharge state) which flows out out of the pressurizing chamber 610C toward the fuel discharge port 600B. The range in which the variable pressure mechanism 700 can adjust the fuel pressure when the pressure regulating mechanism 645 is fully closed is different from the normal fuel pressure adjustment range during normal operation, and the intake valve 630 is fully closed while the lift amount of the plunger 620 is minimized. It becomes the range of the fuel pressure P1 or more.

  FIG. 17 shows the discharge fuel pressure limiting characteristic by the relief valve 690, which shows the change in the discharge fuel pressure limited by the opening of the relief valve 690 with respect to the rotational speed of the internal combustion engine 100. According to FIG. 17, when the rotational speed of the internal combustion engine 100 is relatively low, the discharged fuel pressure is limited to a specified pressure set to the maximum fuel pressure Pmax. However, when the fuel flowing out from the pressurizing chamber 610C toward the fuel discharge port 600B increases as the rotational speed of the internal combustion engine 100 increases, the relief valve 690 discharges excess fuel in the high pressure fuel passage 610E to the low pressure damper 610A. The discharge capacity cannot follow the outflow amount from the pressurizing chamber 610C. For this reason, depending on the rotational speed of the internal combustion engine 100, the discharged fuel pressure is assumed not only to exceed the specified pressure but also to exceed the injection limit fuel pressure Plim of the fuel injection valve 200.

  Considering such a restriction characteristic of the discharge fuel pressure by the relief valve 690, in the fully discharged state at the time of the fully closed failure of the pressure adjusting mechanism 645, the outflow amount from the pressurizing chamber 610C is larger than when the pressure adjusting mechanism 645 is normal. In addition to this, if the lift amount of the plunger 620 by the variable mechanism 700 is increased and the rotational speed of the internal combustion engine 100 is increased, the outflow amount is further increased. Therefore, the discharge fuel pressure of the high-pressure fuel pump 600 becomes the fuel. There is a risk of exceeding the injection limit fuel pressure Plim of the injection valve 200.

  On the other hand, when the target fuel pressure Pt (the white diamond in the figure) is equal to or lower than the fuel pressure P1 when the pressure regulating mechanism 645 is fully closed, the actual fuel pressure Pa (the black circle in the figure) is determined by the variable mechanism 700. It only decreases to the fuel pressure P1, which is the lower limit value of the adjustable fuel pressure range. In this case, the actual fuel pressure Pa is equal to or higher than the target fuel pressure Pt.

  FIG. 18B shows the normal fuel pressure adjustment range of the high pressure fuel pump 600 when the pressure regulating mechanism 645 and the variable mechanism 700 are normal, whereas FIG. 18B shows the high pressure fuel pump when the variable mechanism 700 is at the maximum lift failure. The fuel pressure adjustable range of 600 is shown. The maximum lift failure (failure mode 2) of the variable mechanism 700 is a failure in which the lift amount of the variable mechanism 700 is fixed at the maximum state, and the fuel pressure can be adjusted by the high-pressure fuel pump 600 when the maximum lift failure of the variable mechanism 700 occurs. The range is a fuel pressure adjustment adjustable range by the pressure adjustment mechanism 645.

  At the time of the maximum lift failure of the variable mechanism 700, the fuel pressure adjustable range by the pressure regulating mechanism 645 is different from the normal fuel pressure adjustment range at the normal time, from the fuel pressure P2 higher than the minimum fuel pressure Pmin to a predetermined value. However, when the actual fuel pressure Pa reaches a predetermined value, the valve closing timing of the suction valve 630 is fixed to the intermediate valve closing timing when the actual fuel pressure Pa is a predetermined value by the solenoid actuator 640, but the lift amount of the plunger 620 is always constant. Since the rotational speed of the internal combustion engine 100 increases, the discharge capacity of the relief valve 690 cannot follow the outflow amount from the pressurizing chamber 610C, and the discharge fuel pressure of the high-pressure fuel pump 600 is fuel injection. There is a risk of exceeding the injection limit fuel pressure Plim of the valve 200 (see the thick broken line in the figure).

  On the other hand, when the target fuel pressure Pt (white diamond in the figure) is equal to or lower than the fuel pressure P2 at the time of the maximum lift failure of the variable mechanism 700, the actual fuel pressure Pa (black circle in the figure) is determined by the pressure adjusting mechanism 645. It only decreases to the fuel pressure P2, which is the lower limit value of the adjustable fuel pressure range. In this case, the actual fuel pressure Pa is equal to or higher than the target fuel pressure Pt.

  FIG. 19B shows a normal fuel pressure adjustment range of the high-pressure fuel pump 600 when the pressure regulating mechanism 645 and the variable mechanism 700 are normal, whereas FIG. 19B shows a high-pressure fuel pump when the pressure regulating mechanism 645 is fully open. The fuel pressure adjustable range of 600 is shown. The fully open failure (failure mode 3) of the pressure regulating mechanism 645 is a failure in which the intake valve 630 cannot be closed with the valve fully open.

  If the actual fuel pressure Pa is equal to or greater than a predetermined value when the pressure adjusting mechanism 645 is fully opened, the fuel pressure is adjusted by the variable mechanism 700. Even if the fuel pressure can be adjusted by the variable mechanism 700 regardless of the actual fuel pressure Pa. Since the fuel pressure adjustable range is only from the minimum fuel pressure Pmin to the fuel pressure P2 (see the thick broken line in the figure), the actual fuel pressure Pa is less than a predetermined value. If the actual fuel pressure Pa is less than the predetermined value, the fuel pressure adjustment by the variable mechanism 700 is not performed as described above, so that the actual fuel pressure Pa eventually decreases to the minimum fuel pressure Pmin. In this case, if the target fuel pressure Pt is a value greater than the minimum fuel pressure Pmin, the actual fuel pressure Pa is less than the target fuel pressure Pt.

  FIG. 20B shows the normal fuel pressure adjustment range of the high pressure fuel pump 600 when the pressure adjusting mechanism 645 and the variable mechanism 700 are normal, whereas FIG. 20B shows the high pressure fuel pump when the variable mechanism 700 is at the minimum lift failure. A fuel pressure adjustment range of 600 is shown. The minimum lift failure (failure mode 4) of the variable mechanism 700 is a failure in which the lift amount of the variable mechanism 700 is fixed in a minimum state, and the fuel pressure adjustment by the high-pressure fuel pump 600 when the minimum lift failure of the variable mechanism 700 occurs. The possible range is a fuel pressure adjustment adjustable range by the pressure adjustment mechanism 645.

  At the time of the minimum lift failure of the variable mechanism 700, the fuel pressure adjustable range by the pressure regulating mechanism 645 is equal to or more than the minimum fuel pressure Pmin and less than a predetermined value, like the normal fuel pressure adjustment range at normal time. If the target fuel pressure Pt is less than the predetermined value, the actual fuel pressure Pa can be brought close to the target fuel pressure Pt as in the normal state, but if the target fuel pressure Pt is equal to or greater than the predetermined value, the target fuel pressure Pt is regulated. Since the fuel pressure adjustable range by the mechanism 645 is exceeded, the actual fuel pressure Pa (black circle in the figure) does not rise above a predetermined value. In this case, the actual fuel pressure Pa is less than the target fuel pressure Pt.

  Thus, considering the range in which the fuel pressure can be adjusted by the high-pressure fuel pump 600 when the pressure regulating mechanism 645 or the variable mechanism 700 fails, in particular, according to the failure modes 1 and 2, the discharge fuel pressure of the high-pressure fuel pump 600 becomes the injection limit fuel pressure. It is assumed that Plim is exceeded. For this reason, the fuel pump control device 810 performs the following failure diagnosis and fail-safe processing according to the control program stored in the nonvolatile memory B, so that the fuel pressure adjustment mechanism including the pressure regulating mechanism 645 and the variable mechanism 700 is obtained. After diagnosing whether or not there is a failure while specifying which of failure modes 1 to 4, fail-safe processing corresponding to the failure mode is performed.

[Fault diagnosis and fail-safe processing]
21 and 22 show a fuel pressure adjustment mechanism that is repeatedly executed by the processor A of the fuel pump control device 810 every predetermined time when the fuel pump control device 810 is started in conjunction with the operation of the ignition key. An example of failure diagnosis and fail-safe processing is shown.

  First, in FIG. 21, in step S11, the processor A of the fuel pump control device 810 determines whether or not the actual fuel pressure Pa read from the fuel pressure sensor 800 is equal to or lower than the fail determination fuel pressure Pf. The fail determination fuel pressure Pf is a threshold value for determining whether or not the actual fuel pressure Pa may reach the injection limit fuel pressure Plim of the fuel injection valve 200. For example, from the maximum fuel pressure Pmax or the specified pressure of the relief valve 690 The pressure value can be set higher than the injection limit fuel pressure Plim. When the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa is equal to or less than the fail determination fuel pressure Pf (YES), the process proceeds to step S12. On the other hand, if the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa is higher than the fail determination fuel pressure Pf (NO), the process proceeds to step S15.

  In step S12, similarly to step S1, the processor A of the fuel pump control device 810 determines whether or not the actual fuel pressure Pa read from the fuel pressure sensor 800 has not reached the target fuel pressure Pt. When the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa has not reached the target fuel pressure Pt (YES), the process proceeds to step S13. On the other hand, when the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa has reached the target fuel pressure Pt (NO), in order to maintain the state, failure diagnosis and fail-safe of the fuel pressure adjusting mechanism are performed. End the process.

  In step S13, the processor A of the fuel pump control device 810 determines whether or not the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is within a predetermined range including 0, that is, the deviation between the target fuel pressure Pt and the actual fuel pressure Pa. It is determined whether or not the absolute value (| Pt−Pa |) is equal to or less than the fail determination differential pressure value ΔPc. The fail determination differential pressure value ΔPc is a threshold value for determining whether or not the actual fuel pressure Pa deviates from the target fuel pressure Pt due to a failure of the pressure regulating mechanism 645 including the intake valve 630 and the solenoid actuator 640 or the variable mechanism 700. The value is larger than the mechanism selection threshold value ΔPb in step S3. If the processor A of the fuel pump control device 810 determines that the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is equal to or less than the fail determination differential pressure value ΔPc (YES), the process proceeds to step S14. Proceed. On the other hand, if the processor A of the fuel pump control device 810 determines that the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is greater than the fail determination differential pressure value ΔPc (NO), the process proceeds to step S16. .

  In step S14, the processor A of the fuel pump control device 810 determines that the fuel pressure adjusting mechanism including the pressure adjusting mechanism 645 and the variable mechanism 700 is normal, and if the normal fuel pressure control process of the high pressure fuel pump 600 is stopped. This is resumed, or if the normal fuel pressure control process is not stopped, this is continued, and the failure diagnosis of the fuel pressure adjusting mechanism and the fail safe process are terminated.

  In step S15, the processor A of the fuel pump control device 810 determines that the failure in the failure mode 1 or the failure mode 2 has occurred in the fuel pressure adjusting mechanism including the pressure adjusting mechanism 645 and the variable mechanism 700, and further fails. The process proceeds to step S37 in FIG. 22 to perform the safe process.

  In step S16, the processor A of the fuel pump control device 810 determines that the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is greater than the fail determination differential pressure value ΔPc (| Pt−Pa |> ΔPc). It is determined whether the process continues until Tf is reached. Then, the processor A of the fuel pump control device 810 determines that the state in which the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is greater than the fail determination differential pressure value ΔPc continues until the fail determination time Tf. In the case (YES), the process proceeds to step S17. On the other hand, the processor A of the fuel pump control device 810 determines that the state where the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is greater than the fail determination differential pressure value ΔPc does not continue until the fail determination time Tf is reached. In the case (NO), the process proceeds to step S14.

  In step S17, the processor A of the fuel pump control device 810 determines that a failure has occurred in the fuel pressure adjusting mechanism including the pressure adjusting mechanism 645 and the variable mechanism 700, and further performs step S18 in FIG. Proceed to the process.

  Next, referring to FIG. 22, in step S18, the processor A of the fuel pump control device 810 stops the normal fuel pressure control process of the high-pressure fuel pump 600 shown in FIG. 14 as the fail-safe process. Accordingly, when the pressure adjusting mechanism 645 is normal, the closing timing of the suction valve 630 is fully closed, and when the variable mechanism 700 is normal, the lift amount of the plunger 620 is minimized.

  In step S19, the first deviation ΔPd1 (= | Pt−), which is the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa when the processor A of the fuel pump control device 810 stops the normal fuel pressure control process in the previous step. Pa |) is calculated and stored in a volatile memory C such as a RAM. The first deviation ΔPd1 is calculated after the intake valve 630 is fully closed or the lift amount of the plunger 620 is minimized in step S18.

  In step S20, it is determined whether or not the actual fuel pressure Pa is equal to or higher than the target fuel pressure Pt while the normal fuel pressure control process is stopped. In step S16 of FIG. 21, since the state where the absolute value of the deviation between the target fuel pressure Pt and the actual fuel pressure Pa is greater than the fail determination differential pressure value ΔPc continues until the fail determination time Tf, the determination in step S20 is performed. Thus, it is specified in which failure mode the deviation state between the target fuel pressure Pt and the actual fuel pressure Pa is continued.

  As described above with reference to FIGS. 16 to 20, when the deviation state between the target fuel pressure Pt and the actual fuel pressure Pa continues, the actual fuel pressure Pa becomes equal to or higher than the target fuel pressure Pt. The fully closed failure (failure mode 1) of the variable mechanism 700 or the maximum lift failure (failure mode 2) of the variable mechanism 700, while the actual fuel pressure Pa is less than the target fuel pressure Pt is the fully open failure of the pressure regulating mechanism 645 ( Either failure mode 3) or minimum lift failure of variable mechanism 700 (failure mode 4). Therefore, by determining whether or not the actual fuel pressure Pa is equal to or higher than the target fuel pressure Pt, whether the failure of the fuel pressure adjustment mechanism is failure mode 1 or failure mode 2, failure mode 3 or failure mode 4, It can be specified that it is either one of these.

  In step S20, if the processor A of the fuel pump control device 810 determines that the actual fuel pressure Pa is equal to or higher than the target fuel pressure Pt (YES), the failure of the fuel pressure adjustment mechanism is failure mode 1 or failure mode 2. While determining that the actual fuel pressure Pa is less than the target fuel pressure Pt (NO), it is determined that the failure of the fuel pressure adjustment mechanism is failure mode 3 or failure mode 4. The process proceeds to step S29 while specifying.

  In step S21, the processor A of the fuel pump control device 810 activates the solenoid actuator 640 of the pressure regulating mechanism 645 according to a predetermined operation amount in order to forcibly change the current valve closing timing of the intake valve 630. Is output (operation signal output to the pressure adjustment mechanism).

  In step S22, the processor A of the fuel pump control device 810 sets the target fuel pressure Pt when the normal fuel pressure control process is stopped in step S18, and the actual fuel pressure Pa after the operation signal is output to the pressure adjustment mechanism 645 in the previous step. The second deviation ΔPd2 (= | Pt−Pa |), which is the absolute value of the deviation, is calculated, and this second deviation ΔPd2 is calculated with respect to the first deviation ΔPd1 stored in the volatile memory C in step S19. Determine if it has changed. For example, the processor A of the fuel pump control device 810 determines whether the second deviation ΔPd2 is greater than the first deviation ΔPd1 depending on whether the absolute value of the deviation between the first deviation ΔPd1 and the second deviation ΔPd2 is equal to or greater than a predetermined threshold. It can be determined whether or not it has changed. If the processor A of the fuel pump control device 810 determines that the second deviation ΔPd2 has changed with respect to the first deviation ΔPd1 (YES), the process proceeds to step S23, while the second deviation ΔPd2 is If it is determined that there is no change with respect to 1 deviation ΔPd1 (NO), the process proceeds to step S26.

  In step S23, the processor A of the fuel pump control device 810 diagnoses that the maximum lift failure (failure mode 2) of the variable mechanism 700 has occurred. In subsequent step S24, as a fail-safe process, the control stop of the variable mechanism 700 is determined and an operation signal is not output to the variable mechanism 700, and the process is further performed to adjust the fuel pressure by the pressure adjusting mechanism 645. Proceed to S25.

  In step S25, the processor A of the fuel pump control device 810 performs feedback control as a fail-safe process so that the actual fuel pressure Pa becomes the predetermined fuel pressure Ps by the pressure adjustment mechanism 645. As shown in FIG. 18C, the fail fuel pressure adjustment range in which the pressure adjustment mechanism 645 adjusts the fuel pressure as a fail safe process at the time of the maximum lift failure of the variable mechanism 700 is different from the normal fuel pressure control range, as shown in FIG. From the fuel pressure P2 when the intake valve 630 is fully opened to the fuel pressure until the fully closed state is reached in the maximum amount state. However, the predetermined fuel pressure Ps is arbitrarily set within the range of the fail fuel pressure adjustment by the pressure adjusting mechanism 645, with an upper limit of the fuel pressure that does not exceed the injection limit fuel pressure Plim even if the rotational speed of the internal combustion engine 100 increases. Is done. For example, when the target fuel pressure Pt when the normal fuel pressure control process is stopped is lower than the fuel pressure P2, the processor A of the fuel pump control device 810 can set the predetermined fuel pressure Ps to the fuel pressure P2 (in the drawing). triangle). After the execution of step S25, the failure diagnosis and fail-safe processing of the fuel pressure adjustment mechanism are terminated.

  In step S26, the processor A of the fuel pump control device 810 diagnoses that a fully closed failure (failure mode 1) of the pressure regulating mechanism 645 has occurred. In subsequent step S27, as a fail-safe process, the control stop of the pressure regulating mechanism 645 is determined and an operation signal is not output to the pressure regulating mechanism 645, and the process is performed in order to adjust the fuel pressure by the variable mechanism 700. Proceed to

  In step S28, the processor A of the fuel pump control device 810 performs feedback control so that the actual fuel pressure Pa becomes the predetermined fuel pressure Ps by the variable mechanism 700 as fail-safe processing. As shown in FIG. 16C, the fail fuel pressure adjustment range in which the variable mechanism 700 performs fuel pressure adjustment as a fail-safe process at the time of a fully closed failure of the pressure regulating mechanism 645 is different from the normal fuel pressure control range, as shown in FIG. In the fully closed state, the fuel pressure is from the fuel pressure P1 when the lift amount of the plunger 620 is minimum to the fuel pressure when it is maximum. However, the predetermined fuel pressure Ps is the upper limit of the fuel pressure within the fail fuel pressure adjustment range (fuel pressure P1 or more) by the variable mechanism 700 so that the discharge fuel pressure does not exceed the injection limit fuel pressure Plim even if the rotational speed of the internal combustion engine 100 increases. Is set arbitrarily. The fail fuel pressure adjustment range is the same as the fuel pressure adjustment range shown in FIG. For example, when the target fuel pressure Pt when the normal fuel pressure control process is stopped is lower than the fuel pressure P1, the processor A of the fuel pump control device 810 can set the predetermined fuel pressure Ps to the fuel pressure P1 (in the drawing). triangle). After execution of step S28, the failure diagnosis and fail-safe processing of the fuel pressure adjustment mechanism are terminated.

  In step S29, the processor A of the fuel pump control device 810 outputs an operation signal corresponding to a predetermined operation amount to the variable mechanism 700 in order to forcibly change the lift amount of the plunger 620 (operation to the variable mechanism). Signal output).

  In step S30, as in step S22, the processor A of the fuel pump control device 810 outputs a target fuel pressure Pt when the normal fuel pressure control process is stopped in step S18 and an operation signal to the variable mechanism 700 in the previous step. The second deviation ΔPd2 that is the absolute value of the deviation from the actual fuel pressure Pa from the above is calculated, and whether this second deviation ΔPd2 has changed with respect to the first deviation ΔPd1 stored in the volatile memory C in step S19 Determine whether or not. If the processor A of the fuel pump control device 810 determines that the second deviation ΔPd2 has changed with respect to the first deviation ΔPd1 (YES), the process proceeds to step S31, while the second deviation ΔPd2 is If it is determined that there is no change with respect to 1 deviation ΔPd1 (NO), the process proceeds to step S34.

  In step S31, the processor A of the fuel pump control device 810 diagnoses that a fully open failure (failure mode 3) of the pressure regulating mechanism 645 has occurred. Then, in subsequent step S32, as a fail-safe process, the control stop of the pressure regulating mechanism 645 is determined and an operation signal for the pressure regulating mechanism 645 is not output, and the process is performed in order to perform fuel pressure adjustment by the variable mechanism 700 in step S33. Proceed to

  In step S33, the processor A of the fuel pump control device 810 performs feedback control so that the actual fuel pressure Pa becomes the predetermined fuel pressure Ps by the variable mechanism 700 as fail-safe processing. As shown in FIG. 19C, the fail fuel pressure adjustment range in which the variable mechanism 700 performs the fuel pressure adjustment as a fail-safe process when the pressure regulating mechanism 645 is fully opened is different from the normal fuel pressure control range, as shown in FIG. In this state, the minimum fuel pressure Pmin when the lift amount of the plunger 620 is the minimum is the fuel pressure P2 when the maximum is the maximum. However, the predetermined fuel pressure Ps is arbitrarily set within the fail fuel pressure adjustment range by the variable mechanism 700, with the upper limit being a fuel pressure that does not exceed the injection limit fuel pressure Plim even if the rotational speed of the internal combustion engine 100 increases. The For example, when the target fuel pressure Pt when the normal fuel pressure control process is stopped is higher than the fuel pressure P2, the processor A of the fuel pump control device 810 can set the predetermined fuel pressure Ps to the fuel pressure P2 (in the drawing). triangle). After the execution of step S33, the failure diagnosis and fail-safe processing of the fuel pressure adjustment mechanism are terminated.

  In step S34, the processor A of the fuel pump control device 810 diagnoses that the minimum lift failure (failure mode 4) of the variable mechanism 700 has occurred. Then, in subsequent step S35, as a fail-safe process, the control stop of the variable mechanism 700 is determined and an operation signal for the variable mechanism 700 is not output, and the process proceeds to step S36 in order to adjust the fuel pressure by the pressure adjusting mechanism 645. Proceed.

  In step S36, the processor A of the fuel pump control device 810 performs feedback control so that the actual fuel pressure Pa becomes the predetermined fuel pressure Ps by the pressure adjustment mechanism 645 as fail-safe processing. As shown in FIG. 20C, the fail fuel pressure adjustment range in which the pressure adjustment mechanism 645 adjusts the fuel pressure as a fail safe process at the time of the minimum lift failure of the variable mechanism 700 is different from the normal fuel pressure control range, as shown in FIG. From the minimum fuel pressure Pmin when the intake valve 630 is fully opened to the fuel pressure P1 until the fully closed state is reached with the amount being minimum. However, the predetermined fuel pressure Ps is arbitrarily set within the range of the fail fuel pressure adjustment by the pressure adjusting mechanism 645, with an upper limit of the fuel pressure that does not exceed the injection limit fuel pressure Plim even if the rotational speed of the internal combustion engine 100 increases. Is done. For example, when the target fuel pressure Pt when the normal fuel pressure control process is stopped is higher than the fuel pressure P1, the processor A of the fuel pump control device 810 can set the predetermined fuel pressure Ps to the fuel pressure P1 (in the drawing). triangle). After execution of step S36, the failure diagnosis and fail-safe processing of the fuel pressure adjusting mechanism are terminated.

  About step S37 and step S38, since the process similar to step S18 and step S19 is performed, description of the processing content is abbreviate | omitted. Since Step S37 and Step S38 are processes executed after it is determined in Step S15 of FIG. 21 that the failure of the failure mode 1 or the failure mode 2 has occurred in the fuel pressure adjusting mechanism, the fuel pump control device 810 After executing step S38, processor A skips step S20 and advances the process to step S21.

  According to the fuel pump control device 810 of the first embodiment as described above, the fuel pressure adjustment including the variable mechanism 700 that changes the lift amount of the plunger 620 and the pressure adjustment mechanism 645 that changes the valve closing timing of the intake valve 630. Which of the mechanisms is malfunctioning is diagnosed while identifying the failure modes 1 to 4 based on the state of the discharge fuel pressure (actual fuel pressure Pa). Then, the fuel pump control device 810 stops the control of one of the fuel pressure adjustment mechanisms diagnosed as a failure as a fail-safe process, and the normal fuel pressure Pa is adjusted according to the failure mode by the other one that is normal. In the range, feedback control is performed so that the predetermined fuel pressure Ps is arbitrarily set with the fuel pressure at which the discharge fuel pressure does not exceed the injection limit fuel pressure Plim even if the rotational speed of the internal combustion engine 100 increases. Therefore, according to the fuel pump control device 810 of the first embodiment, even if a failure occurs in the fuel pressure adjusting mechanism, the fuel pressure discharged from the high-pressure fuel pump 600 is changed to the fuel injection valve 200 while allowing the internal combustion engine 100 to continue operating. Exceeding the injection limit fuel pressure Plim can be suppressed.

Second Embodiment
Next, a control device according to a second embodiment of the present invention applied to the fuel injection system of FIG. 1 will be described. In addition, about the structure which is common in 1st Embodiment, description is abbreviate | omitted or simplified by attaching | subjecting the same code | symbol.

  The fuel pump control device 810 executes processing different from that of the first embodiment in failure diagnosis and fail-safe processing of the fuel pressure adjustment mechanism.

  FIG. 23 shows a failure diagnosis of the fuel pressure adjustment mechanism, which is repeatedly executed every predetermined time by the processor A of the fuel pump control device 810 when the fuel pump control device 810 is activated in conjunction with the operation of the ignition key. An example of fail-safe processing is shown.

  In step S101, the processor A of the fuel pump control device 810 stores the first actual fuel pressure Pa1 read from the fuel pressure sensor 800 in a volatile memory C such as a RAM.

  In step S102, the processor A of the fuel pump control device 810 determines whether either the pressure adjustment mechanism 645 or the variable mechanism 700 among the fuel pressure adjustment mechanisms has continuously adjusted the fuel pressure for a predetermined time Td or longer. That is, each time the normal fuel pressure control process of the high pressure fuel pump 600 in FIG. 14 is executed, the time during which the pressure regulating mechanism 645 continuously adjusts the fuel pressure is equal to or longer than the predetermined time Td by repeating Step S4 or Step S7. Or by repeating Step S5 or Step S8, it is determined whether or not the time during which the variable mechanism 700 continuously performs fuel pressure adjustment is equal to or longer than the predetermined time Td. The predetermined time Td is a time estimated that the actual fuel pressure Pa has reached the target fuel pressure Pt by feedback control. If the processor A of the fuel pump control device 810 determines that either the pressure adjusting mechanism 645 or the variable mechanism 700 has continuously adjusted the fuel pressure for a predetermined time Td or longer (YES), the process is stepped. On the other hand, if it is determined that either the pressure adjustment mechanism 645 or the variable mechanism 700 has not performed fuel pressure adjustment continuously for a predetermined time Td or longer (NO), the failure diagnosis and fail-safe processing of the fuel pressure adjustment mechanism are performed. Exit.

  In step S103, the current second actual fuel pressure Pa2 read from the fuel pressure sensor 800 by the processor A of the fuel pump control device 810 changes compared to the first actual fuel pressure Pa1 stored in the volatile memory C in step S101. Judge whether or not there is. For example, the processor A of the fuel pump control device 810 determines whether the second actual fuel pressure Pa2 is the first actual fuel pressure Pa2 depending on whether the absolute value of the deviation between the first actual fuel pressure Pa1 and the second actual fuel pressure Pa2 is equal to or less than a predetermined threshold. It can be determined whether or not the fuel pressure Pa1 has changed. If the processor A of the fuel pump control device 810 determines that the second actual fuel pressure Pa2 has not changed compared to the first actual fuel pressure Pa1 (YES), the process proceeds to step S104, while the second If it is determined that the actual fuel pressure Pa2 has changed compared to the first actual fuel pressure Pa1 (NO), the process proceeds to step S105.

  In step S104, the processor A of the fuel pump control device 810 determines that a failure has occurred in the fuel pressure adjusting mechanism including the pressure adjusting mechanism 645 and the variable mechanism 700, and the normal operation of the high pressure fuel pump 600 shown in FIG. While stopping the fuel pressure control process, the process proceeds to step S106 to further perform the fail-safe process.

  In step S105, the processor A of the fuel pump control device 810 determines that the fuel pressure adjusting mechanism including the pressure adjusting mechanism 645 and the variable mechanism 700 is normal, and if the normal fuel pressure control process of the high pressure fuel pump 600 is stopped. This is resumed, or if the normal fuel pressure control process is not stopped, this is continued, and the failure diagnosis of the fuel pressure adjusting mechanism and the fail safe process are terminated.

  In step S106, the processor A of the fuel pump control device 810 determines whether or not the variable pressure mechanism 700 determines that the fuel pressure adjustment has been performed continuously for the predetermined time Td or longer in step S102 among the fuel pressure adjustment mechanisms. Determine whether. If the processor A of the fuel pump control device 810 determines that the fuel pressure that has been continuously adjusted is the variable mechanism 700 (YES), the process proceeds to step S107, while the fuel pressure is continuously adjusted. If it is determined that what has been adjusted is not the variable mechanism 700 (NO), the process proceeds to step S110.

  In step S107, the processor A of the fuel pump control device 810 diagnoses that either the failure mode 2 or the failure mode 4 has occurred in the variable mechanism 700. In subsequent step S108, as a fail-safe process, the control stop of the variable mechanism 700 is determined and an operation signal is not output to the variable mechanism 700, and the process proceeds to step S109 in order to perform fuel pressure adjustment by the pressure adjusting mechanism 645. Proceed.

  In step S109, the processor A of the fuel pump control device 810 performs feedback control so that the actual fuel pressure Pa becomes the predetermined fuel pressure Ps by the pressure adjustment mechanism 645 as fail-safe processing. The predetermined fuel pressure Ps is a failure fuel pressure adjustment range by the pressure adjustment mechanism 645 in the failure mode 2 (see FIG. 18C) and a failure fuel pressure adjustment range by the pressure adjustment mechanism 645 in the failure mode 4 (see FIG. 20C). Even if the rotational speed of the internal combustion engine 100 increases, the fuel pressure is set arbitrarily so that the discharged fuel pressure does not exceed the injection limit fuel pressure Plim. After the execution of step S109, the failure diagnosis and fail-safe processing of the fuel pressure adjustment mechanism is terminated.

  In step S110, the processor A of the fuel pump control device 810 diagnoses that either the failure mode 1 or the failure mode 3 has occurred in the pressure regulating mechanism 645. Then, in the subsequent step S111, the control of the pressure regulating mechanism 645 is stopped by not outputting an operation signal to the pressure regulating mechanism 645 as fail-safe processing.

  In step S112, the processor A of the fuel pump control device 810 performs feedback control so that the actual fuel pressure Pa becomes the predetermined fuel pressure Ps by the variable mechanism 700 as fail-safe processing. The predetermined fuel pressure Ps is an internal combustion error in the failure fuel pressure adjustment range of the variable mechanism 700 in the failure mode 1 (see FIG. 16C) and the failure fuel pressure adjustment range of the variable mechanism 700 in the failure mode 3 (see FIG. 19C). Even if the rotational speed of the engine 100 is increased, the fuel pressure is set arbitrarily so that the discharged fuel pressure does not exceed the injection limit fuel pressure Plim. After execution of step S112, the failure diagnosis and fail-safe processing of the fuel pressure adjustment mechanism are terminated.

  According to the fuel pump control device 810 of the second embodiment as described above, which of the fuel pressure adjusting mechanisms including the variable mechanism 700 and the pressure adjusting mechanism 645 has failed is determined based on the discharge fuel pressure (actual fuel pressure Pa). Diagnosis is based on the condition. Then, the fuel pump control device 810 stops the control of one of the fuel pressure adjustment mechanisms diagnosed as a failure as a fail-safe process, and the actual fuel pressure Pa is set in place of the target fuel pressure Pt by the other that is normal. The feedback control is performed so that the predetermined fuel pressure Ps is reached. Here, the predetermined fuel pressure Ps is arbitrarily set within the fail fuel pressure adjustment range of the other, which is normal, with the fuel pressure at which the discharge fuel pressure does not exceed the injection limit fuel pressure Plim as the upper limit even if the rotational speed of the internal combustion engine 100 increases. Is done. Therefore, according to the fuel pump control device 810 of the second embodiment, as in the first embodiment, even if a failure occurs in the fuel pressure adjustment mechanism, the high-pressure fuel pump 600 can be operated while allowing the internal combustion engine 100 to continue operating. Can be prevented from exceeding the injection limit fuel pressure Plim of the fuel injection valve 200.

  In addition, according to the fuel pump control device 810 of the second embodiment, it is diagnosed which of the pressure adjusting mechanism 645 and the variable mechanism 700 has failed without specifying the failure modes 1 to 4. Compared with the first embodiment, the processing load on the fuel pump control device 810 is reduced.

  As described above, the invention made by the inventor has been specifically described based on the first embodiment and the second embodiment. However, the present invention is not limited to the above embodiment, and is as follows. Various modifications can be made without departing from the scope of the present invention.

  In step S22 or step S30 of the failure diagnosis and fail-safe processing (see FIG. 22) of the first embodiment, the processor A of the fuel pump control device 810 stores the current second deviation ΔPd2 stored in step S19. Although it is determined whether or not it has changed from 1 deviation ΔPd1, instead of storing the first actual fuel pressure Pa1 in step S19, the current second actual fuel pressure Pa2 is determined in step S22 or step S30. It may be determined whether or not there is a change from the first actual fuel pressure Pa1 stored in step S19.

  Of the failure diagnosis and fail-safe processing (see FIG. 22) of the first embodiment, in step S22 or step S30, the processor A of the fuel pump control device 810 determines that the operating state of the internal combustion engine 100 is the first deviation in step S19. The second deviation ΔPd2 may be calculated on condition that ΔPd1 is equivalent to that calculated.

  In step S18, the processor A of the fuel pump control device 810 stops the normal fuel pressure control process of the high-pressure fuel pump 600 in the failure diagnosis or fail-safe process (see FIG. 22) of the first embodiment. If 645 is normal, the closing timing of the intake valve 630 is fully closed. If the variable mechanism 700 is normal, the lift amount of the plunger 620 is minimized. Instead, the following is performed. It may be. That is, in step S18, the processor A of the fuel pump control device 810 holds the duty ratio of PWM supplied to the solenoid actuator 640 to fix the closing timing of the intake valve 630 by the pressure adjusting mechanism 645, and the variable mechanism 700. The feedback control for adjusting the discharge fuel pressure of the high-pressure fuel pump 600 toward the target fuel pressure Pt may be stopped by holding the operation amount and fixing the lift amount of the plunger 620 in the current state.

  In the failure diagnosis or fail-safe process of the first embodiment (see FIG. 22), the processor A of the fuel pump control device 810 outputs an operation signal to the pressure regulating mechanism 645 in step S21, while the variable mechanism 700 in step S29. However, instead of this, in either step S21 or step S29, the operation signal may be output to either the pressure regulating mechanism 645 or the variable mechanism 700. Alternatively, the processor A of the fuel pump control device 810 may output an operation signal to the pressure adjusting mechanism 645 in step S29 while outputting an operation signal to the variable mechanism 700 in step S21.

  Of the failure diagnosis and fail-safe processing (see FIG. 23) of the second embodiment, in step S103, the processor A of the fuel pump control device 810 determines that the operating state of the internal combustion engine 100 is the first actual fuel pressure Pa1 in step S101. The current second actual fuel pressure Pa2 and the first actual fuel pressure Pa1 may be compared on the condition that they are equivalent to those stored.

  In the first embodiment and the second embodiment, the failure diagnosis and fail-safe processing are executed in the fuel pump control device 810, but instead, may be executed in the engine control device 830 or other control device. . Alternatively, failure diagnosis and fail-safe processing may be executed by a single control device in which the functions of the fuel pump control device 810 and the engine control device 830 are integrated.

DESCRIPTION OF SYMBOLS 100 ... Internal combustion engine, 200 ... Fuel injection valve, 600 ... High pressure fuel pump, 620 ... Plunger, 630 ... Suction valve, 640 ... Solenoid actuator, 645 ... Pressure regulation mechanism, 660 ... Cam mechanism, 680 ... Spring, 700 ... Variable mechanism 810: Fuel pump controller, Pa, Pa1, Pa2: Actual fuel pressure, Ne: Rotational speed of internal combustion engine, Plim: Injection limit fuel pressure, Ps: Predetermined fuel pressure, Pt: Target fuel pressure, ΔPc: Fail judgment differential pressure value, Tf ... Fail determination time, ΔPd1 ... first deviation, ΔPd2 ... second deviation

Claims (10)

A fuel injection valve that injects fuel into the cylinder, and a fuel pump that lifts the plunger against the urging force of the spring by a cam mechanism driven by the internal combustion engine, boosts the fuel, and discharges the fuel to the fuel injection valve; A control device for an internal combustion engine, comprising: a variable mechanism for changing a lift amount of the plunger; and a pressure adjusting mechanism for adjusting the pressure of the fuel boosted by the fuel pump,
When the discharged fuel pressure, which is the pressure of fuel discharged from the fuel pump to the fuel injection valve, is less than a predetermined value, the variable pressure mechanism is controlled to minimize the lift amount of the plunger, and the pressure regulating mechanism is controlled. The fuel is regulated according to the discharged fuel pressure, and when the discharged fuel pressure is equal to or greater than the predetermined value, the variable mechanism is controlled while controlling the pressure regulating mechanism to fix the pressure regulated level at the predetermined value. And changing the lift amount of the plunger according to the discharge fuel pressure,
Based on the state of the discharged fuel pressure, it is determined whether or not a failure has occurred in the variable mechanism or the pressure regulating mechanism, and if it is determined that the failure has occurred, the failure has occurred. One control determined to be stopped is stopped, and the other one is set to a predetermined fuel pressure at which the discharge fuel pressure does not exceed the injection limit fuel pressure of the fuel injection valve even if the rotational speed of the internal combustion engine increases. A control device for an internal combustion engine for controlling.   2. The control device for an internal combustion engine according to claim 1, wherein the state of the discharged fuel pressure includes a duration of a state in which the discharged fuel pressure deviates from a target fuel pressure.   The control apparatus for an internal combustion engine according to claim 2, wherein the state of the discharge fuel pressure further includes a magnitude relationship between the target fuel pressure and the discharge fuel pressure.   The state of the discharge fuel pressure further includes a first deviation between the target fuel pressure and the discharge fuel pressure when the control of the variable mechanism and the pressure adjustment mechanism is stopped, and the variable mechanism or the pressure adjustment from the stop. The control apparatus for an internal combustion engine according to claim 3, including a change state between the target fuel pressure and the second deviation between the discharged fuel pressure when one of the mechanisms is forcibly operated.   The second deviation is calculated when one of the variable mechanism or the pressure regulating mechanism is selected based on a comparison between the discharged fuel pressure and the target fuel pressure, and the selected one is forcibly activated. The control device for an internal combustion engine according to claim 4.   The second deviation is calculated when the pressure regulating mechanism is forcibly operated when the discharged fuel pressure is equal to or higher than the target fuel pressure, while when the discharged fuel pressure is less than the target fuel pressure. Is calculated when the variable mechanism is forcibly operated. The control device for an internal combustion engine according to claim 5.   When it is determined that the discharged fuel pressure is equal to or higher than the target fuel pressure, and the second deviation is determined to have changed from the first deviation, the pressure adjustment is performed so that the discharged fuel pressure becomes the predetermined fuel pressure. The control device for an internal combustion engine according to claim 6, which controls the mechanism.   When it is determined that the discharged fuel pressure is equal to or higher than the target fuel pressure and it is determined that the second deviation has not changed from the first deviation, the variable mechanism is set so that the discharged fuel pressure becomes the predetermined fuel pressure. The control device for an internal combustion engine according to claim 6, wherein the control device is controlled.   When it is determined that the discharged fuel pressure is less than the target fuel pressure and it is determined that the second deviation has changed from the first deviation, the variable mechanism is configured so that the discharged fuel pressure becomes the predetermined fuel pressure. The control apparatus for an internal combustion engine according to claim 6, which controls the engine.   When it is determined that the discharged fuel pressure is less than the target fuel pressure and it is determined that the second deviation has changed from the first deviation, the pressure adjustment is performed so that the discharged fuel pressure becomes the predetermined fuel pressure. The control device for an internal combustion engine according to claim 6, which controls the mechanism.