JP4134216B2 - Internal combustion engine control device - Google Patents

Description

  The present invention relates to a direct injection type internal combustion engine control apparatus that directly injects fuel pressurized by a high-pressure fuel pump driven by an internal combustion engine into a combustion chamber, and in particular, an automatic stop condition is established during operation of the internal combustion engine. The internal combustion engine is automatically stopped while controlling the piston stop position so that the piston stops at a predetermined position.When the automatic start condition is satisfied while the piston is stopped, combustion is performed in the predetermined cylinder. The present invention relates to a control technique for a high-pressure fuel pump applied to an internal combustion engine controller that is automatically started.

In recent years, with the aim of reducing fuel consumption and reducing CO2 emissions, the so-called idle stop is a feature that automatically stops the internal combustion engine when idling and then automatically restarts when a restart condition such as a start operation is established. An internal combustion engine control device having a function has been developed.
In restart at idle stop, it is required to start immediately according to the start operation. Therefore, restarting with a starter (starting motor) takes too much time until the start is completed. It is not preferable as a starting method when applying a stop.

Therefore, a method has been proposed in which fuel is directly injected into a specific cylinder of an internal combustion engine that is in a stopped state without using a starter, ignition and combustion are performed, and the internal combustion engine is immediately started with the combustion energy. Yes.
However, in the method of restarting the internal combustion engine without using a starter as described above, when the piston stop position is not appropriate (for example, when the piston is stopped at a position very close to top dead center or bottom dead center). ), The amount of air in the cylinder to be combusted at the time of restart is too small to obtain sufficient combustion energy necessary for starting, or the stroke of applying the combustion energy after ignition to the piston is too short. Therefore, there is a possibility that the engine cannot be started normally.

In addition, since the cylinder in which combustion is performed at the time of restart is in a state of maintaining a certain level of compression pressure, in order to inject and supply fuel into the cylinder, the fuel pressure of the injected fuel from the fuel injection valve However, it is also necessary that the pressure is maintained at a state equal to or higher than the compression pressure of the cylinder.
That is, in order to start the internal combustion engine without using a starter, when the engine is automatically stopped, the piston is stopped at a position appropriate for restart, and the injection fuel pressure that overcomes the compression pressure of the stopped cylinder is ensured. It is most important to keep it.

Therefore, an internal combustion engine control having a stop position control function of stopping the piston at an appropriate position by increasing the intake air amount during a predetermined period after the automatic stop condition is satisfied and the internal combustion engine is stopped. An apparatus has been proposed (see, for example, Patent Document 1).
According to the conventional device described in Patent Document 1, when the internal combustion engine goes to stop, the amount of intake air is increased so that the piston is in a top dead center in the cylinder that is in the compression stroke and the cylinder that is in the expansion stroke when stopped. It is possible to increase the reaction force (resistance when the piston moves in the direction of the top dead center) that pushes back the piston when it approaches, and to stop the piston within a predetermined range in the middle of the stroke with high probability.

In addition, the rotational position of each cylinder of the internal combustion engine and the generation position of the load received by the internal combustion engine by the fuel discharge operation of the high-pressure fuel pump are configured in advance to have a predetermined relationship, immediately before the internal combustion engine stops. An internal combustion engine control device having a stop position control function of discharging fuel by forcibly driving a high-pressure fuel pump is proposed (for example, see Patent Document 2).
According to the conventional device described in Patent Document 2, the piston is located between the top dead center and the bottom dead center so that the momentary work of the high-pressure fuel pump is maximized when the piston is at the top dead center. Sometimes the high-pressure fuel pump is configured to minimize the momentary work, and immediately before the internal combustion engine stops, the high-pressure fuel pump is forcibly driven to discharge the fuel to ensure the injected fuel pressure after the stop. can do. In addition, the internal combustion engine going to stop is loaded, and the action in the direction in which the instantaneous work of the high-pressure fuel pump is minimized (that is, the direction in which the piston is moved approximately halfway between the top dead center and the bottom dead center) is increased. The piston can be stopped within a predetermined range in the middle of the stroke with higher probability.

  In Patent Documents 1 and 2, the proper position stop of the piston is generally about 90 ° CA (crank angle) after top dead center (that is, near the middle between top dead center and bottom dead center). Yes, if the piston can be stopped at this position, good combustion can be obtained by the moderately present in-cylinder air and the fuel supplied at the time of restart, and it is easy to generate sufficient torque for restart It is said.

  By the way, in the conventional apparatus described in Patent Document 1, in order to stop the piston at an appropriate position, the piston is stopped at an appropriate position by increasing the intake air amount during a predetermined period when the internal combustion engine goes to stop. However, there is no mention of the influence on the piston stop position when fuel is discharged from the high-pressure fuel pump until the internal combustion engine stops.

Normally, the fuel discharge amount of the high-pressure fuel pump is feedback-controlled so that the fuel pressure in the stock pressure chamber matches the target fuel pressure, so that the deviation between the fuel pressure in the stock pressure chamber and the target fuel pressure until the internal combustion engine stops. Feedback control is performed according to the above.
That is, when the control of the stop position is being executed in order to stop the piston at an appropriate position, or when the fuel pressure in the animal pressure chamber is lower than the target fuel pressure even immediately before the internal combustion engine is stopped. Since the fuel corresponding to the deviation between the detected value of the fuel pressure and the target fuel pressure is discharged, a load change is caused to the internal combustion engine that is going to stop.

Since the deviation between the fuel pressure in the stock pressure chamber and the target fuel pressure varies from time to time, the degree of load change that occurs is expected to be indefinite, and in some cases, the load change due to fuel discharge from the high-pressure fuel pump may be disturbed. As a result, the piston stop position varies.
That is, in a cylinder injection type internal combustion engine control apparatus that automatically stops when the automatic stop condition is satisfied and automatically starts when the automatic start condition after the automatic stop is satisfied, When fuel is discharged from the high-pressure fuel pump in order to return the fuel pressure in the pressure chamber to the target fuel pressure, the fuel discharge operation (load change to the internal combustion engine) becomes a disturbance and the piston cannot be stopped at the proper position. In this case, the piston stop position is out of the proper range, and the combustion energy necessary for restart cannot be obtained, and the desired automatic start may not be achieved.

Hereinafter, the influence on the piston stop position due to the load change until the internal combustion engine stops will be described with reference to FIG.
FIG. 8 is a timing chart showing the operation of the conventional automatic stop control device. From the top, the automatic stop condition satisfaction flag FS, stop position control (intake air amount control) execution flag FA, and fuel cut execution flag FC are shown. Each state is indicated by a solid line.
In the states of the flags FS, FA, and FC, the HI (high) side indicates “1” and the LO (low) side indicates “0”.

Further, in FIG. 8, the behavior of the fuel pressure P in the stock pressure chamber (solid line) and the target fuel pressure PO (one-dot chain line) are shown in the lower part of each flag FS, FA, FC.
Further, the fuel injection INJ (filled black square) written on the lower side of the fuel pressure P schematically shows the drive timing and the injection amount of the fuel injection valve by its position and size.
Similarly, a fuel discharge PMP (outlined square) written on the lower side of the fuel injection INJ schematically shows the driving timing and discharge amount of the high-pressure fuel pump by its position and size.
Further, in the lowermost stage in FIG. 8, the behavior of the actual engine speed NE (solid line), the behavior of the ideal engine speed NEi when the piston stops at an appropriate position (two-dot chain line), It is shown.

Next, the behavior of each flag and each parameter in FIG. 8 will be sequentially described.
First, in the normal operation period up to time T1, the internal combustion engine is in an operating state such as idling, and all the three flags FS, FA, and FC related to the automatic stop are reset to “0”.
Further, during the normal operation period, the fuel pressure PF is repeatedly reduced from the target fuel pressure PO by the fuel injection INJ by the fuel injection valve, and again returned to the target fuel pressure PO by the fuel discharge PMP of the high-pressure fuel pump.

Next, at time T1, when it is detected that the internal combustion engine is idling, the automatic stop condition establishment flag FS is set to “1”, and a series of controls for automatic stop is started.
If it is determined at time T2 that the engine speed is suitable for starting the fuel cut after FS = 1, the fuel cut flag FC is set to “1”, and at the same time, the stop position control is performed. The execution flag FA is also set to “1”.

Hereinafter, fuel injection continues to be prohibited until the internal combustion engine is actually stopped after the fuel cut is started with FS = 1.
Further, in the stop position control period in which FA = 1 (a predetermined period from time T2 to immediately before the internal combustion engine stops), the intake air amount increase control is executed to control the piston stop position. .
Hereinafter, the period from the time when the increase control of the intake air amount is completed and FA = 0 again to FA = 0 is referred to as a period immediately before the internal combustion engine is completely stopped.

  By the way, when FC = 1 and fuel cut is started at time T2, the internal combustion engine loses torque and goes to stop. At this time, stop position control is started, and after time T2, the fuel is discharged from the high-pressure fuel pump. When the engine is not discharged, no load change occurs with respect to the internal combustion engine to be stopped. Therefore, the internal combustion engine follows the locus of the ideal engine speed NEi indicated by the two-dot chain line and stops at time T5. To do. In this case, the piston stops at an appropriate position.

  However, actually, since the fuel pressure PF is reduced by the last injected fuel injected in the period from time T1 to time T2, the fuel discharge PMP for returning the fuel pressure PF to the target fuel pressure PO is performed at time T2. To the time T3. By this fuel discharge PMP, the fuel pressure PF returns to the target fuel pressure PO at time T3.

However, since the fuel discharge PMP executed during the stop position control period changes the load on the internal combustion engine to be stopped, the internal combustion engine follows the trajectory of the engine rotational speed NE indicated by the solid line while Stop at T4b.
At this time, if the time difference Xb (= T5−T4b) between when it stops at the time T4b and when it stops at the time T5 is large, the probability that the piston stops at the appropriate stop position is lowered. In this case, the combustion energy required for restart cannot be obtained, and good automatic start cannot be realized.

  FIG. 8 shows an example of operation when the fuel pressure PF is lowered by the last injected fuel. For example, for the purpose of maintaining a high fuel pressure during stoppage, after FS = 1. Even when the target fuel pressure PO is changed to a high value, or when the fuel pressure PF decreases in the period immediately before stopping for some reason, a disturbance occurs due to the fuel discharge operation of the high-pressure fuel pump, resulting in the same problem. Expected.

  On the other hand, in the conventional apparatus described in Patent Document 2, fuel is discharged from the high-pressure fuel pump during the period immediately before the stop to control the fuel pressure in the animal pressure chamber to the target fuel pressure, and a load is generated due to fuel discharge from the high-pressure fuel pump. By doing so, the internal combustion engine immediately before the stop is loaded and the piston is stopped at an appropriate position.However, considering that the load amount due to the fuel discharge of the high-pressure fuel pump differs depending on the feedback control described above. Not.

  In other words, if the deviation between the fuel pressure in the stock pressure chamber and the target fuel pressure is different from time to time, the amount of fuel discharged from the high-pressure fuel pump is different (that is, the load applied to the internal combustion engine is also different from time to time). As a result, the load applied to the internal combustion engine immediately before the stop becomes indefinite and the piston stop position varies, and as a result, in the worst case, the piston stop position is out of the proper range and the combustion required for restart Energy may not be available and the desired automatic start may not be achieved.

Further, the technique described in Patent Document 2 is “configured so that the rotational position of each cylinder of the internal combustion engine and the generation position of the load of the internal combustion engine generated by the fuel discharge operation of the high-pressure fuel pump have a predetermined relationship”. It is assumed that it is.
Hereinafter, the problem in Patent Document 2 will be supplementarily described with reference to the explanatory diagram of FIG. 9 showing the control process of the four-cylinder internal combustion engine.

In FIG. 9, the upper stage shows a piston stroke indicating the rotational position of each cylinder of a four-cylinder internal combustion engine (number of cylinders M = 4). The piston stroke of each cylinder is “intake → compression → expansion (explosion). ) → Exhaust ”and repeat vertical movement.
For example, when each cylinder is in the intake stroke, the fuel is sequentially injected from the fuel injection valve of each cylinder in the order of “# 1 → # 3 → # 4 → # 2 cylinder”.

Further, the lower part of FIG. 9 shows a configuration example of two strokes a and b of the high-pressure fuel pump during the cycle of the fuel injection stroke of each cylinder.
The pump stroke a indicates “a configuration of a high-pressure fuel pump having N (= 3) fuel discharge strokes 1a to 3a while the fuel injection stroke of each cylinder makes a round” which does not correspond to the technique of Patent Document 2. The pump stroke b corresponds to the technique of Patent Document 2 “a configuration of a high-pressure fuel pump having N (= 4) fuel discharge strokes 1 b to 4 b during the cycle of the fuel injection stroke of each cylinder”. Yes.

As in the pump stroke b (Patent Document 2), in an internal combustion engine having a configuration in which “N = 4 discharge strokes during one cycle of the fuel injection stroke of each of the four cylinders”, the piston position of each cylinder All the fuel discharge strokes 1b to 4b can be evenly arranged at positions where the top or bottom of the fuel becomes (see the broken line).
Therefore, when the fuel is discharged from the high-pressure fuel pump immediately before the stop, there is an action in a direction to move to a point where the instantaneous work of the high-pressure fuel pump is minimized (approximately between the top dead center and the bottom dead center). The same tendency occurs in each fuel discharge stroke, and the effect as described in Patent Document 2 is obtained.

However, in the internal combustion engine of “a configuration in which N = 3 discharge strokes during one cycle of the fuel injection stroke of each of the four cylinders” as in the pump stroke a, the piston position of each cylinder is at the top or It becomes impossible to arrange | position all the fuel discharge strokes 1a-3a equally in the position (refer broken line) used as a bottom.
Therefore, when the fuel is discharged from the high-pressure fuel pump immediately before the stop, the force acting on the piston does not have the same tendency in each fuel discharge stroke, and there is a high possibility that the piston stop position shifts from the optimum position.

That is, in the case of the pump stroke a, the fuel discharge stroke 1a can be arranged at a position where the piston position is the top or bottom (see the broken line), but the fuel discharge strokes 2a and 3a are arranged at completely different piston positions. I have to do it.
Thus, in the “M cylinder internal combustion engine (M is a natural number equal to or greater than“ 3 ”, for example,“ 4 ”), N times (N is“ N <M ”) during one cycle of the fuel injection stroke to each cylinder. In the case of “a configuration in which the fuel discharge stroke is a natural number equal to or greater than“ 2 ”, for example“ 2 ”or“ 3 ”)”, the technique described in Patent Document 2 is applied to an already manufactured internal combustion engine. Attempting to do so requires a change in configuration, which can lead to a significant cost increase.

JP 2004-124754 A JP 2004-301047 A

  In the conventional internal combustion engine control device, in the case of Patent Document 1, the influence on the piston stop position when fuel is discharged from the high-pressure fuel pump during the automatic stop control until the internal combustion engine stops is considered. Therefore, the load change caused by the fuel discharge of the high-pressure fuel pump is disturbed and the piston stop position varies, and in the worst case, the piston stop position is out of the proper range and the combustion energy required for restart There is a problem that the desired automatic start cannot be achieved.

Further, in the case of Patent Document 2, since it is not considered that the load amount due to fuel discharge of the high-pressure fuel pump differs depending on feedback control, the load applied to the internal combustion engine immediately before stopping becomes indefinite and the piston There is a problem that the stop position varies, the piston stop position deviates from an appropriate range, and combustion energy necessary for restart cannot be obtained, and a desired automatic start cannot be achieved.
Furthermore, the technique disclosed in Patent Document 2 is described as follows: “In an M-cylinder internal combustion engine (M is a natural number equal to or greater than“ 3 ”), N times (N is“ N <M If it is intended to be applied to an internal combustion engine manufactured in “a configuration in which a fuel discharge stroke of“ 2 ”or more”, which is “natural number” becomes “,” the configuration needs to be changed, resulting in a significant increase in cost.

  The present invention has been made in order to solve the above-described problems. By improving the control of the high-pressure fuel pump applied to the internal combustion engine control device, the automatic stop can be performed without causing a significant increase in cost. Suppresses changes in the load on the internal combustion engine caused by fuel discharge by the high-pressure fuel pump that satisfies the conditions, reduces the variation in the piston stop position, increases the probability that the piston stops at the proper position, and obtains a good automatic start An object of the present invention is to obtain an internal combustion engine control device capable of performing

  An internal combustion engine control device according to the present invention is driven by an internal combustion engine, various sensors that detect the operating state of the internal combustion engine, a stock pressure chamber that accumulates pressurized fuel, a fuel pressure sensor that detects a fuel pressure in the stock pressure chamber, and A mechanical high-pressure fuel pump that discharges the pressurized fuel into the pressure chamber, an electromagnetic flow control valve that adjusts the amount of fuel discharged from the high-pressure fuel pump to the pressure chamber, and a high-pressure fuel pump A fuel pressure control unit that controls the flow rate control valve, and a livestock control unit so that the fuel discharge amount becomes a necessary amount for matching the fuel pressure in the livestock pressure chamber with a target fuel pressure set in advance according to the operating state of the internal combustion engine. A fuel injection valve that directly injects the fuel in the pressure chamber into the combustion chamber of the internal combustion engine, the fuel pressure control unit determines the fuel discharge amount of the high-pressure fuel pump after the stop condition of the internal combustion engine is satisfied. Limited to a predetermined amount or less It has a discharge amount limitation means that, restricted execution conditions of the fuel discharge amount by the discharge amount limiting means includes a predetermined period after establishment of a condition for stopping the internal combustion engine until the internal combustion engine comes to a complete stop.

  According to the present invention, the internal combustion engine heading for stoppage is limited by limiting the fuel discharge amount of the high-pressure fuel pump to a predetermined amount or less from a predetermined time after the automatic stop condition is satisfied until the internal combustion engine is completely stopped. It is possible to suppress the occurrence of a load disturbance with respect to, increase the probability of stopping the piston at an appropriate position, and to perform a good automatic start.

Embodiment 1 FIG.
Hereinafter, an internal combustion engine control apparatus having an automatic stop control function according to Embodiment 1 of the present invention will be described with reference to the drawings.
1 is a block diagram schematically showing an internal combustion engine control apparatus according to Embodiment 1 of the present invention, and particularly shows a related configuration of a high-pressure fuel pump control unit.
FIG. 2 is a functional block diagram showing a specific configuration of the ECU 60 in FIG.
In FIG. 1, the number of cylinders M of the internal combustion engine 40 is four, and the high-pressure fuel is generated while the crankshaft (not shown) of the internal combustion engine 40 makes two revolutions (that is, while the camshaft 24 makes one revolution). A configuration example in the case where the fuel discharge stroke N of the pump 20 is 3 times is shown.

  In FIG. 1, the control device of the internal combustion engine 40 is a mechanical high pressure having an electromagnetic and normally open flow control valve 10 having a solenoid 12, a cylinder 21, a plunger 22, and a pressurizing chamber 23 as a fuel supply system. A fuel pump 20, a camshaft 24 having a pump cam 25 having three protrusions, a fuel tank 30 filled with fuel, and a low pressure connected to the fuel tank 30 via a low pressure fuel pump 31 and a low pressure regulator 32. A passage 33, a high-pressure passage (discharge passage) 34 connected to the pressurizing chamber 23 of the high-pressure fuel pump 20, a pressure accumulation chamber 36 connected to the high-pressure passage 34 via a discharge valve (check valve) 35, a relief A relief passage 38 connecting between the pressure accumulating chamber 36 and the fuel tank 30 via the valve 37, and the fuel accumulated in the pressure accumulating chamber 36 are supplied to each combustion chamber (M = 4) of the internal combustion engine 40. And a direct injection supplying fuel injection valve 39).

Further, as a control system for controlling the fuel discharge amount of the high-pressure fuel pump 20, an ECU 60 for controlling the excitation timing of the solenoid 12 of the flow control valve 10 consisting of an electromagnetic valve (closing of the flow control valve 10) is provided. Yes.
Detection signals from various sensors such as a fuel pressure sensor 61, an ignition switch 62, a cam angle sensor 63, a crank angle sensor 64, and an accelerator position sensor 65 are input to the ECU 60 as operation information of the internal combustion engine 40.

  As shown in FIG. 2, the ECU 60 includes a target fuel pressure setting means 601, a feedback amount calculation means 602, a flow rate control valve control means 603, an internal combustion engine control means 604 that controls the operation of the internal combustion engine 40, and an internal combustion engine. And an idle stop control means 605 for controlling 40 automatic stops and automatic starting.

The ECU 60 is also connected to various other sensors and actuator groups (not shown) necessary for realizing the functions of the units 601 to 605.
The flow rate control valve control means 603 in the ECU 60 functions as a fuel pressure control unit, and the fuel discharge amount of the high pressure fuel pump 20 is set in advance according to the operating state of the internal combustion engine 40 with the fuel pressure PF in the livestock pressure chamber 36. The flow rate control valve 10 is controlled so as to be a necessary amount to match the target fuel pressure PO.

Returning to FIG. 1, the low-pressure fuel pump 31 pumps up the fuel in the fuel tank 30 and discharges it to the low-pressure passage 33.
The high-pressure fuel pump 20 is driven by the internal combustion engine 40 via the pump cam 25, sucks the fuel discharged from the low-pressure fuel pump 31 into the pressurizing chamber 23, and discharges the pressurized fuel into the stock pressure chamber 36.

The low pressure passage 33 is connected to the upstream side of the pressurizing chamber 23 in the high pressure fuel pump 20 via the flow rate control valve 10. That is, the flow control valve 10 is disposed in a fuel passage connecting the low pressure passage 33 and the pressurizing chamber 23, and adjusts the fuel discharge amount supplied from the high pressure fuel pump 20 to the livestock pressure chamber 36.
The discharge valve 35 is disposed in a high-pressure passage 34 that connects the pressurizing chamber 23 and the animal pressure chamber 36.
The fuel injection valve 39 directly injects and supplies the high-pressure fuel in the stock pressure chamber 36 into each combustion chamber of the cylinder (M = 4) of the internal combustion engine 40.
The fuel pressure sensor 61 detects the fuel pressure PF in the animal pressure chamber 36 and outputs it to the ECU 60.

On the low pressure passage 33 side of the fuel supply system, the fuel discharged from the low pressure fuel pump 31 is adjusted to a predetermined low pressure value by the low pressure regulator 32, and the flow rate control is performed when the plunger 22 moves down in the cylinder 21. It is introduced into the pressurizing chamber 23 through the valve 10.
The plunger 22 in the high-pressure fuel pump 20 reciprocates in the cylinder 21 in synchronization with the rotation of the internal combustion engine 40. As a result, the high pressure fuel pump 20 sucks fuel into the pressurizing chamber 23 from the low pressure passage 33 via the flow rate control valve 10 during the fuel suction stroke (during the downward movement of the plunger 22). 22), the fuel in the pressurizing chamber 23 is pressurized to a high pressure while the flow rate control valve 10 is being driven to close the valve, and the fuel is supplied to the livestock pressure chamber 36 via the discharge valve 35.
As is apparent from this operation mechanism, when the high-pressure fuel pump 20 discharges the fuel, the fuel in the pressurizing chamber 23 is pressurized. Therefore, a load corresponding to the degree of the pressurizing operation is applied to the internal combustion engine 40. Will join.

The pressurizing chamber 23 is defined by the inner peripheral wall surface of the cylinder 21 and the upper end surface of the plunger 22, and the lower end of the plunger 22 is pressed against a pump cam 25 provided on the cam shaft 24 of the internal combustion engine 40. When the pump cam 25 rotates in conjunction with the rotation of the shaft 24, the plunger 22 reciprocates in the cylinder 21, so that the volume in the pressurizing chamber 23 changes in an enlarged / reduced manner.
In the configuration of FIG. 1, the pump cam 25 has three protrusions, and three fuel discharge strokes (N = 3 times) are obtained while the cam shaft 24 makes one rotation.

The high-pressure passage 34 connected to the downstream side of the pressurizing chamber 23 is connected to the livestock pressure chamber 36 via a discharge valve 35 consisting of a check valve that allows only the flow of fuel from the pressurization chamber 23 toward the livestock pressure chamber 36. It is connected.
The livestock pressure chamber 36 accumulates and holds the high-pressure fuel discharged from the pressurizing chamber 23 and is connected in common to each fuel injection valve 39 of the internal combustion engine 40 so that the accumulated high-pressure fuel is supplied to the fuel injection valve. Distribute to 39.
The relief valve 37 connected to the stock pressure chamber 36 is a normally closed valve that opens at a predetermined fuel pressure (opening pressure set value) or higher, and the fuel pressure in the stock pressure chamber 36 is set to a valve opening pressure set value for the relief valve 37. Opens when attempting to rise above. As a result, the fuel in the stock pressure chamber 36 that is about to rise above the valve opening pressure set value is returned to the fuel tank 30 through the relief passage 38, and the fuel pressure in the stock pressure chamber 36 does not become excessive.

  The flow rate control valve 10 provided in the low pressure passage 33 connecting the low pressure fuel pump 31 and the pressurizing chamber 23 is driven to close when the solenoid 12 is excited under the control of the ECU 60. When the plunger 22 moves up in the cylinder 21 (the volume of the pressurizing chamber 23 is reduced), the plunger 22 is sucked into the pressurizing chamber 23 while the flow control valve 10 is controlled to open (demagnetization of the solenoid 12). Since the fuel that is present is returned from the pressurizing chamber 23 to the low-pressure passage 33 through the flow control valve 10, the high-pressure fuel is not supplied to the livestock pressure chamber 36.

  On the other hand, after the flow rate control valve 10 is closed at a predetermined timing while the plunger 22 is moving up in the cylinder 21, the fuel pressurized in the pressurizing chamber 23 is discharged into the discharge passage 34 and is stored through the discharge valve 35. It is supplied to the pressure chamber 36.

The ECU 60 detects the fuel pressure PF in the stock pressure chamber 36 detected by the fuel pressure sensor 61, the rotational phase angle CP of the internal combustion engine 40 detected by the cam angle sensor 63, and the engine rotation of the internal combustion engine 40 detected by the crank angle sensor 64. Various operating states such as the speed NE and the depression amount AP of an accelerator pedal (not shown) detected by the accelerator position sensor 65 are captured.
Then, the ECU 60 determines the target fuel pressure based on the various operating states taken in, calculates the target discharge amount necessary for the fuel pressure PF in the animal pressure chamber 36 to coincide with the target fuel pressure, and according to this target discharge amount Thus, the valve closing timing of the flow control valve 10 is controlled to control the amount of fuel discharged from the high-pressure fuel pump 20 to the livestock pressure chamber 36.

Next, a specific configuration for realizing the fuel discharge amount control of the high-pressure fuel pump 20 in the first embodiment of the present invention will be described with reference to the functional block diagram of FIG.
Note that the related elements 10, 12, 61 to 65 of the ECU 60 in FIG. 2 are assigned the same reference numerals as those in FIG.
Further, since the internal combustion engine control means 604 for controlling the operation state of the internal combustion engine 40 and the idle stop control means 605 for controlling the automatic stop and automatic start of the internal combustion engine 40 are well known, detailed description thereof is omitted here. To do.

In FIG. 2, the ECU 60 includes a fuel pressure PF in the pressure accumulation chamber 36 detected by the fuel pressure sensor 61, an ignition state signal IG detected by the ignition switch 62, and the rotation of the internal combustion engine 40 detected by the cam angle sensor 63. The phase angle CP, the engine speed NE of the internal combustion engine 40 detected by the crank angle sensor 64, and the accelerator pedal depression amount AP detected by the accelerator position sensor 65 are input.
Thus, the ECU 60 controls the valve closing timing of the flow control valve 10 (actually the excitation timing of the solenoid 12) based on the detection information of various sensors.

  In the ECU 60, the target fuel pressure setting means 601, the feedback amount calculation means 602, and the flow rate control valve control means 603 that contribute to fuel discharge control of the high-pressure fuel pump 20 have the ignition switch 62 turned on and the internal combustion engine 40. Is programmed so that the control is prohibited when the ignition switch 62 is turned off or the internal combustion engine 40 is exhausted.

The target fuel pressure setting means 601 is based on the map data corresponding to the engine speed NE of the internal combustion engine 40 detected by the crank angle sensor 64 and the accelerator pedal depression amount AP detected by the accelerator position sensor 65. Determine the fuel pressure PO.
The feedback amount calculation means 602 includes a subtractor 621 that calculates a pressure deviation ΔPF between the target pressure PO and the detected fuel pressure PF, a proportional calculation unit 622 and an integral calculation unit 623 that use the pressure deviation ΔPF, and a proportional calculation term QFBP. And an adder 624 for calculating the fuel discharge feedback amount QFB by adding the integral calculation term QFBI.

The flow control valve control means 603 outputs an adder 631 for adding the fuel discharge feedback amount QFB and the fuel injection amount QINJ, and outputs a target fuel discharge amount QO based on the output value (= QFB + QINJ) of the adder 631 and a predetermined amount QLMT. And a solenoid drive means 633 for setting the drive timing TD using the rotational speed NE and the target fuel discharge quantity QO.
The solenoid driving unit 633 includes a driving timing map.

The adder 631 functions as a normal target discharge amount calculating means, adds the fuel discharge feedback amount QFB and the fuel injection amount QINJ obtained by the internal combustion engine control means 604, and adds the normal target discharge amount QO ( = QFB + QINJ).
The discharge amount limiting means 632 switches between the limit value calculation unit 634 for obtaining the limit value of the target discharge amount QO based on the predetermined amount QLMT, and the normal target discharge amount QO and the limit value via the contacts C1 and C2. And a selector switch 635 for outputting.

  The limit value calculation unit 634 inputs a limit value (≦ QLMT) based on the minimum value between the output value of the adder 631 (target discharge amount QO = QFB + QINJ) and the predetermined amount QLMT to the contact C2 of the changeover switch 635.

The changeover switch 635 has a contact C1 for selecting a target discharge amount QO (= QFB + QINJ) at a normal time and a contact C2 for selecting a limited target discharge amount for automatic stop control.
The output value (= QFB + QINJ) of the adder 631 is input to the contact C1 of the changeover switch 635, and the output value (limit value) of the limit value calculation unit 634 is input to the contact C2 of the changeover switch 635.

The changeover switch 635 includes a fuel cut execution flag FC from the internal combustion engine control means 604, an automatic stop condition satisfaction flag FS from the idle stop restriction means 605, a fuel pressure PF from the fuel pressure sensor 61, and a crank angle sensor 64. The engine rotational speed NE from is input.
Although not shown in FIG. 2, the stop position control execution flag FA is generated in the ECU 60 when the stop position control is executed.

Accordingly, the changeover switch 635 switches and outputs the target discharge amount QO at the normal time or at the time of restriction based on the input parameters including the flags FC and FS.
That is, at the normal time, the changeover switch 635 of the discharge amount limiting unit 632 is connected to the contact C1 side, and the normal target discharge amount QO calculated by the adder (target discharge amount calculating unit) 631 is solenoid driven. Output to means 633.

On the other hand, when the idle stop control means 605 determines that the automatic stop condition is satisfied, the idle stop control means 605 notifies the discharge amount restriction means 632 that the automatic stop condition is satisfied (FS = 1).
Accordingly, the discharge amount limiting means 632 switches the changeover switch 635 to the contact C2 side in order to execute the automatic stop control, and the target discharge amount limited to the predetermined amount QLMT or less from the normal target discharge amount (= QFB + QINJ). QO is output to the solenoid driving means 633.

  If the predetermined amount QLMT is set to a minimum value (= 0) in advance, the limited target discharge amount QO (when the changeover switch 635 is switched to the contact C2 side in order to execute the automatic stop control. = 0) is output to the solenoid driving means 633.

Here, a specific calculation process of the feedback amount calculation unit 602 will be described.
In the feedback amount calculation means 602, the subtractor 621 calculates a fuel pressure deviation ΔPF (= PO−PF) between the target fuel pressure PO and the fuel pressure PF, and the proportional calculation unit 622 performs a proportional integral calculation based on the fuel pressure deviation ΔPF. The fuel discharge feedback amount QFB of the high-pressure fuel pump 20 is calculated.
At this time, the proportional calculation term QFBP calculated by the proportional calculation unit 622 is obtained as the following expression (1) based on the fuel pressure deviation ΔPF.

  QFBP = ΔPF × KP (1)

However, in Equation (1), KP is a proportional coefficient.
That is, the proportional calculation term QFBP is a positive value proportional to the fuel pressure deviation ΔPF when ΔPF ≧ 0 (the sign of the fuel pressure deviation ΔPF is “+ (plus)”). Conversely, ΔPF < In the case of 0 (sign of fuel pressure deviation ΔPF is “− (minus)”), a negative value proportional to the fuel pressure deviation ΔPF is obtained.

  On the other hand, the integral calculation term QFBI calculated by the integral calculation unit 623 in the feedback amount calculation means 602 is, for example, the following expression (in accordance with the direction of the sign (“+” or “−”) of the fuel pressure deviation ΔPF) ( Either one of the formula 2) or the formula (3) is selected and determined.

(If △ PF ≧ 0)
QFBI = QFBI previous value + KI (2)
(If PF <0)
QFBI = QFBI previous value−KI (3)

However, in Expressions (2) and (3), KI is an integration coefficient.
That is, the integral operation term QFBI is a value that is larger by the integral coefficient KI according to the equation (2) when the sign of the fuel pressure deviation ΔPF is “+”, and conversely when the sign of the fuel pressure deviation ΔPF is “−”. Becomes a small value by the integral coefficient KI according to the equation (3).
Finally, the adder 624 calculates an addition value of the proportional calculation term QFBP and the integral calculation term QFBI as the fuel discharge feedback amount QFB.

  Hereinafter, in the flow rate control valve control means 603, the solenoid drive means 633 is based on the target discharge amount QO via the discharge amount restriction means 632 and the engine rotational speed NE from the crank angle sensor 64. Is set to an excitation timing TD of the solenoid 12 for driving to close the valve at a predetermined timing, and the solenoid 12 is driven and controlled.

  When the solenoid 12 is energized in this way, the flow control valve 10 is driven to close at a predetermined timing. Therefore, in normal times, the target fuel discharge amount QO obtained by the adder (target discharge amount calculating means) 631 is obtained. The fuel is discharged from the high-pressure fuel pump 20 into the stock pressure chamber 36, the fuel in the stock pressure chamber 36 increases, and the fuel pressure PF in the stock pressure chamber 36 matches the target fuel pressure PO.

On the other hand, when the idle stop control unit 605 determines that the automatic stop condition is satisfied (the automatic stop condition satisfied flag FS is set to “1”), a limit value calculation unit in the discharge amount limiting unit 632. Since the target fuel discharge amount QO limited to a predetermined amount QLMT or less by 634 is input to the solenoid driving means 633 via the changeover switch 635, the fuel discharge amount of the high-pressure fuel pump 20 is a limit value not more than the predetermined amount QLMT. Controlled based on
When the predetermined amount QLMT is set to the minimum value (= 0) and the target fuel discharge amount QO = QLMT (= 0), the solenoid 12 is not excited and the high-pressure fuel pump 20 supplies the fuel. Can be prevented from being discharged (that is, the fuel discharge amount = 0).

Next, the control operation of the ECU 60 according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.
In FIG. 3, the ECU 60 first determines whether or not the ignition switch 62 is in an ON state based on the ignition state signal IG from the ignition switch 62 (step S101), and the ignition switch 62 is in an OFF state (ie, , No), the excitation of the solenoid 12 is prohibited (step S111), and the process routine of FIG. 3 is exited. In this case, since the solenoid 12 is not excited, fuel is not discharged from the high-pressure fuel pump 20.

  On the other hand, if it is determined in step S101 that the ignition switch 62 is in the ON state (ie, Yes), it is subsequently determined whether or not the engine is in the engine stall state based on the engine speed NE from the crank angle sensor 64 (step S101). If it is determined that the engine is in the stalled state (ie, Yes), excitation of the solenoid 12 is prohibited (step S111), and the process routine of FIG. 3 is exited.

  On the other hand, if it is determined in step S102 that the engine is not in the stalled state (that is, No), then whether or not the cylinder identification of the internal combustion engine 42 has been completed based on the rotational phase angle CP from the cam angle sensor 63 is determined. If it is determined (step S103) and it is determined that cylinder identification has not been completed (ie, No), excitation of the solenoid 12 is prohibited (step S111), and the process routine of FIG. 3 is exited.

  On the other hand, if it is determined in step S103 that the cylinder identification has been completed (that is, Yes), the target fuel pressure setting means 601 determines that the engine rotational speed NE from the crank angle sensor 64 and the accelerator pedal from the accelerator position sensor 65 are. A target fuel pressure PO is determined based on the depression amount AP (step S104).

Subsequently, the subtractor 621 in the feedback amount calculation means 602 calculates a fuel pressure deviation ΔPF (= PO−PF) between the target fuel pressure PO and the fuel pressure PF from the fuel pressure sensor 61 (step S105).
Further, the proportional calculation unit 622 in the feedback amount calculation means 602 calculates the proportional calculation term QFBP from the above-described equation (1) based on the fuel pressure deviation ΔPF, and the integral calculation unit 623 calculates the above-mentioned based on the fuel pressure deviation ΔPF. The integral calculation term QFBI is calculated from the equations (2) and (3), and the adder 624 adds the proportional calculation term QFBP and the integral calculation term QFBI to calculate the fuel discharge feedback amount QFB (= QFBP + QFBI) ( Step S106).

Next, the discharge amount limiting means 632 in the flow control valve control means 603 determines whether or not the automatic stop condition satisfaction flag FS is set to “1” (step S107), and the automatic stop condition is satisfied. If it is determined that FS = 1 (that is, Yes), the output value from the limit value calculation unit 634 is selected as the target discharge amount QO, and the target discharge amount for automatic stop control limited to a predetermined amount QLMT or less. QO is calculated (step S112).
At this time, in the limit value calculation unit 634, the target discharge amount QO for automatic stop control is the minimum of the output value (= QFB + QINJ) of the adder 624 and the predetermined amount QLMT as shown in the following equation (4). Value is set.

  QO = Min. {(QFB + QINJ), QLMT} (4)

As described above, when the predetermined amount QLMT = 0 is set, the target discharge amount QO based on the equation (4) is limited (fixed) to “0”.
On the other hand, if it is determined in step S107 that the automatic stop condition is not satisfied and FS = 0 (that is, No), the discharge amount limiting means 632 uses the output value from the adder 624 as the target discharge amount QO. The normal target discharge amount QO (= QFB + QINJ) is calculated (step S108).

  Subsequent to the calculation processing of the target discharge amount QO (steps S112 and S108), the solenoid drive means 633 in the flow rate control valve control means 603 determines whether the target fuel discharge amount QO calculated by either one or the crank angle sensor 64 is used. The excitation timing TD of the solenoid 12 is set to drive the flow control valve 10 at a predetermined timing based on the engine rotational speed NE (step S109), and the excitation of the solenoid 12 is executed at the excitation timing TD. (Step S110), the process routine of FIG. 3 is exited.

As a result, when it is determined in step S107 that FS = 1 (satisfaction of the automatic stop condition), the target fuel discharge amount QO for automatic stop control (calculated in step S112) limited to a predetermined amount QLMT or less is calculated. Since the fuel is discharged from the high-pressure fuel pump 20 to the stock pressure chamber 36, the fuel in the stock pressure chamber 36 is increased by a discharge amount limited to such an extent that the stop position control is not affected.
On the other hand, if it is determined in step S107 that FS = 0 (the automatic stop condition is not satisfied), the normal target fuel discharge amount QO (calculated in step S108) whose maximum value is not limited is calculated as the high pressure fuel pump. Since the fuel is discharged from 20 to the stock pressure chamber 36, the fuel in the stock pressure chamber 36 is increased by a necessary amount, and the fuel pressure PF in the stock pressure chamber 36 is controlled to coincide with the target fuel pressure PO.

  As described above, according to the first embodiment of the present invention, when the automatic stop condition is satisfied during the operation of the internal combustion engine 40, the piston stop position is controlled so that the piston of the internal combustion engine 40 stops at a predetermined position. In an internal combustion engine control device that automatically stops and automatically starts by performing combustion in a predetermined cylinder when an automatic start condition is satisfied during automatic stop, a flow rate control valve control means 603 (fuel pressure control unit) in the ECU 60 Has a discharge amount limiting means 632 that limits the fuel discharge amount of the high-pressure fuel pump 20 to a predetermined amount QLMT or less after the stop condition of the internal combustion engine 40 is satisfied, and the fuel discharge amount restriction execution condition by the discharge amount limiting means 632 Includes a predetermined period from when the stop condition of the internal combustion engine 40 is satisfied until the internal combustion engine 40 is completely stopped. Therefore, the internal combustion engine 40 is completely stopped after the automatic stop condition is satisfied. Until, it is limited to the extent that the fuel discharge amount does not become disturbance for the stop position control when the high pressure fuel pump 20 is actuated.

Therefore, since the load change with respect to the internal combustion engine 40 toward the stop can be suppressed, the piston stop position does not deviate from the appropriate range, the combustion energy necessary for the restart can be reliably obtained, and a good automatic Start-up can be realized.
Here, the predetermined amount QLMT for limiting the fuel discharge amount by the discharge amount limiting means 632 is a load on the internal combustion engine 40 in the fuel discharge operation of the high-pressure fuel pump 20 as a value after experimental verification, for example. Even if a change occurs, the value is set such that the influence on the piston stop position control is acceptable.

Further, in the discharge amount limiting means 632, when the fuel discharge amount of the high-pressure fuel pump 20 in a predetermined period is fixed to a minimum value (for example, QLMT = 0), the solenoid 12 is not excited and the high-pressure fuel pump The fuel discharge amount from 20 can be set to “0”.
In this case, since the load change with respect to the internal combustion engine 40 which goes to a stop can further be suppressed, the deviation | shift amount from the appropriate range of a piston stop position can further be suppressed.

Embodiment 2. FIG.
In the first embodiment (see FIG. 3), only the predetermined period until the internal combustion engine 40 is completely stopped is considered as the execution condition for limiting the amount of fuel discharged from the high-pressure fuel pump 20. The fuel cut period from when the fuel cut control for stopping the fuel injection from the fuel injection valve 39 is started until the internal combustion engine 40 is completely stopped is included in the fuel discharge amount restriction execution condition. May be.

Hereinafter, referring to FIG. 4 together with FIGS. 1 and 2, a control process according to Embodiment 2 of the present invention in which the fuel cut period is included in the fuel discharge amount restriction execution condition will be described.
FIG. 4 is a flowchart showing a control process of the high pressure fuel pump 20 for automatic stop control according to the second embodiment of the present invention. The same processes as those described above (see FIG. 3) are denoted by the same reference numerals. Detailed description is omitted.

In this case, the only difference from the above (FIG. 3) is that the determination process (step S213) of the fuel cut execution flag FC is inserted immediately before the calculation process (step S112) of the target discharge amount QO for automatic stop.
Further, the configuration of the internal combustion engine control apparatus according to Embodiment 2 of the present invention is as shown in FIGS. 1 and 2, and only the partial function of the discharge amount limiting means 632 in the ECU 60 is different.

  That is, the ECU 60 (high pressure fuel pump control device) according to Embodiment 2 of the present invention establishes the automatic stop condition (automatic stop condition establishment flag FS =) from the idle stop control unit 605 in the changeover switch 635 of the discharge amount limiting unit 632. 1) and the fact that the internal combustion engine control means 604 has notified the execution of fuel cut (fuel cut execution flag FC = 1) (FS = 1, and FC = 1), the fuel discharge amount of the high-pressure fuel pump 20 is limited to a predetermined amount QLMT or less by switching from the normal contact C1 side to the contact C2 side for executing automatic stop control. Control is performed by the fuel discharge amount QO.

  In FIG. 4, first, by the same steps S101 to S106 as described above, when the ignition switch 62 is in the ON state, the internal combustion engine 40 is not in the stalled state, and the cylinder identification is completed, the target fuel pressure PO and the fuel pressure PF are changed. The fuel discharge feedback amount QFB is calculated from the proportional calculation term QFBP and the integral calculation term QFBI based on the fuel pressure deviation ΔPF.

Subsequently, if it is determined in step S107 that the automatic stop condition establishment flag FS = 1 (the automatic stop condition is established), it is determined whether or not the fuel cut execution flag FC is set to “1” ( Step S213).
In step S213, if the fuel cut start condition is satisfied and it is determined that FC = 1 (that is, Yes), the process proceeds to step S112, and is limited to a predetermined amount QLMT or less as shown in the above equation (4). The target discharge amount QO for the automatic stop control is calculated, and the process proceeds to step S109.

On the other hand, if the fuel cut start condition is not satisfied in step S213 and it is determined that FC = 0 (that is, No), the process proceeds to step S108, and the normal target discharge amount QO (= QFB + QINJ) is calculated. Then, the process proceeds to step S109.
Thereafter, the aforementioned steps S109 to S111 are executed, and the processing routine of FIG. 4 is exited.

  As a result, when both the conditions of FS = 1 in step S107 (satisfying automatic stop condition) and FC = 1 in step S213 (satisfying fuel cut start condition) are satisfied, the condition is limited to a predetermined amount QLMT or less. Since the target fuel discharge amount QO for automatic stop control (calculated in step S112) is discharged from the high-pressure fuel pump 20 to the livestock pressure chamber 36, the discharge amount is limited to a level that does not affect the stop position control. The fuel in the stock pressure chamber 36 increases.

  On the other hand, if FS = 0 (automatic stop condition is not established) in step S107 or FC = 0 (fuel cut start condition is not established) is determined in step S213, the maximum value is not limited. Since the target fuel discharge amount QO (calculated in step S108) is discharged from the high-pressure fuel pump 20 to the livestock pressure chamber 36, the fuel in the livestock pressure chamber 36 increases by a necessary amount, and the fuel pressure PF in the livestock pressure chamber 36 increases. Coincides with the target fuel pressure PO.

  As described above, according to the second embodiment of the present invention, even if the automatic stop condition is satisfied (FS = 1), the high-pressure fuel is not changed until the fuel cut is actually started (FC = 1). When an opportunity to discharge the fuel from the pump 20 is obtained, the fuel is discharged at a normal target discharge amount QO that is not limited (a fuel amount necessary for returning the fuel pressure PF in the stock pressure chamber 36 to the target fuel pressure PO). Therefore, the fuel pressure PF in the stock pressure chamber 36 when the internal combustion engine 40 is stopped can be stopped while maintaining it as high as possible.

The determination condition in step S213 is, for example, “the fuel discharge stroke has passed a predetermined number of times since FC = 1 and FC = 1” or “a predetermined time has elapsed since FC = 1”. As described above, a delay may be provided at the start of execution.
In this case, even after the fuel cut is started with FC = 1, the target fuel discharge amount QO at the normal time is changed from the high-pressure fuel pump 20 to the animal pressure chamber 36 for a predetermined number of times or until a predetermined time is reached. After the discharge and the elapse of a predetermined period, the target fuel discharge amount QO for automatic stop control limited to a predetermined amount QLMT or less is discharged from the high-pressure fuel pump 20 to the livestock pressure chamber 36.

Here, with reference to FIG. 7, a supplementary explanation will be given on the function and effect of the second embodiment of the present invention.
FIG. 7 is a timing chart showing the operation according to the second embodiment of the present invention, and shows the behavior of each parameter corresponding to the timing chart in the prior art (see FIG. 8).
In FIG. 7, the times T1, T2, and T5 corresponding to the normal operation period, the stop position control period, and the period immediately before the stop are the same as those described in FIG.

Also in FIG. 7, after the automatic stop condition is satisfied (FS = 1) at time T1, the fuel cut flag FC = 1 is set at time T2, the fuel injection from the fuel injection valve is stopped, and the internal combustion engine 40 is Head to the stop.
However, in this case, since the fuel discharge amount after time T2 is limited, the load change is reduced with respect to the internal combustion engine 40 to be stopped.

Accordingly, it is possible to follow the locus of the engine rotational speed NE indicated by the solid line and to stop at the time T4a very close to the time T5 that is an ideal stop position when the piston can be stopped at an appropriate position.
As a result, the time difference Xa between the time T5, which is an ideal stop position when the piston can be stopped at an appropriate position, and the actual stop position T4a is significantly reduced compared to the time difference Xb in FIG. That is, the change in the load on the internal combustion engine 40 to be stopped is suppressed, the variation in the piston stop position is reduced, the probability that the piston stops at the appropriate position is increased, and a good automatic start can be realized.

Further, as shown in FIG. 7, by limiting the fuel discharge amount after time T2, the internal combustion engine 40 is able to determine that “in the M cylinder internal combustion engine (M is a natural number of 3 or more), the fuel injection stroke to each cylinder is Even if it has already been manufactured in the configuration where the fuel discharge stroke is N times (N is a natural number greater than or equal to “2”, where “N <M”, “N <M”), there is no need to change the configuration. There is no cost increase.
The behavior and operational effects of the engine speed NE shown in FIG. 7 are not limited to the second embodiment of the present invention, and are the same in other embodiments.

Embodiment 3 FIG.
In the second embodiment (see FIG. 4), the internal combustion engine 40 is completely stopped after the fuel cut control is started as a condition for executing the restriction of the fuel discharge amount from the high-pressure fuel pump 20 after the stop condition is satisfied. In consideration of the fuel cut period until the engine is cut, the low rotation speed period from when the engine rotation speed NE of the internal combustion engine 40 falls below the predetermined rotation speed NEo until the internal combustion engine 40 is completely stopped is limited to the fuel discharge amount. It may be included in the execution condition.

Hereinafter, referring to FIG. 5 together with FIGS. 1 and 2, a control process according to Embodiment 3 of the present invention in which the low rotation speed period is included in the fuel discharge amount restriction execution condition will be described.
FIG. 5 is a flowchart showing a control process of the high-pressure fuel pump 20 for automatic stop control according to Embodiment 3 of the present invention. The same processes as those described above (see FIGS. 3 and 4) are denoted by the same reference numerals. A detailed description will be omitted.

In this case, only the determination process (step S313) of the engine rotational speed NE is inserted instead of the determination process (step S213) of the fuel cut execution flag FC described above (FIG. 4).
Further, the configuration of the internal combustion engine control apparatus according to Embodiment 3 of the present invention is as shown in FIGS. 1 and 2, and only a partial function of the discharge amount limiting means 632 in the ECU 60 is different.

  That is, the ECU 60 (high pressure fuel pump control device) according to Embodiment 3 of the present invention is notified of the establishment of the automatic stop condition (FS = 1) from the idle stop control means 605 at the changeover switch 635 of the discharge amount restriction means 632. And when the engine rotational speed NE from the crank angle sensor is lower than the predetermined rotational speed NEo (FS = 1 and NE <NEo) Switching from the contact C1 side at the time to the contact C2 side for executing the automatic stop control, the fuel discharge amount of the high-pressure fuel pump 20 is controlled with the target fuel discharge amount QO limited to a predetermined amount QLMT or less.

  In FIG. 5, first, following steps S101 to S106 similar to those described above, the state of the automatic stop condition satisfaction flag FS is determined in step S107, and if it is determined that FS = 1 (the automatic stop condition is satisfied). Then, it is determined whether or not the engine rotational speed NE of the internal combustion engine 40 is lower than the predetermined rotational speed NEo (step S313).

If it is determined in step S313 that NE <NEo (that is, Yes), the process proceeds to step S112, and the target discharge amount QO for automatic stop control limited to a predetermined amount QLMT or less as in the above-described equation (4). And the process proceeds to step S109.
On the other hand, if it is determined in step S313 that NE ≧ NEo (that is, No), the process proceeds to step S108, the normal target discharge amount QO (= QFB + QINJ) is calculated, and the process proceeds to step S109.
Thereafter, the above-described steps S109 to S111 are executed to exit the processing routine of FIG.

  As a result, when both the conditions of FS = 1 in step S107 (satisfying automatic stop condition) and NE <NEo (satisfying low rotational speed condition) in step S313 are satisfied, it is limited to a predetermined amount QLMT or less. Since the target fuel discharge amount QO for automatic stop control (calculated in step S112) is discharged from the high-pressure fuel pump 20 to the livestock pressure chamber 36, the discharge amount is limited to a level that does not affect the stop position control. The fuel in the stock pressure chamber 36 increases.

  On the other hand, if it is determined in step S107 that FS = 0 (automatic stop condition is not established) or NE ≧ NEo (low rotational speed condition is not established) in step S313, the maximum value is not limited. Since the target fuel discharge amount QO (calculated in step S108) is discharged from the high-pressure fuel pump 20 to the animal pressure chamber 36, the fuel in the animal pressure chamber 36 is increased by a required amount, and the fuel pressure in the animal pressure chamber 36 is increased. PF becomes equal to the target fuel pressure PO.

  As described above, according to the third embodiment of the present invention, even when the automatic stop condition is satisfied (FS = 1), until the engine rotational speed NE of the internal combustion engine 40 actually falls below the predetermined rotational speed NEo. In addition, when an opportunity to discharge the fuel from the high-pressure fuel pump 20 is obtained, the target discharge amount QO in the normal time that is not limited (the fuel required to return the fuel pressure PF in the stock pressure chamber 36 to the target fuel pressure PO). Therefore, the fuel pressure PF in the stock pressure chamber 36 when the internal combustion engine 40 is stopped can be maintained at a high level as much as possible and stopped.

Embodiment 4 FIG.
In the third embodiment (see FIG. 5), as an execution condition for limiting the amount of fuel discharged from the high-pressure fuel pump 20 after the stop condition is satisfied, the internal combustion engine starts after the engine rotational speed NE falls below a predetermined rotational speed NEo. In consideration of the low rotation speed period until 40 completely stops, the fuel discharge amount limit execution condition is that the fuel pressure PF in the animal pressure chamber 36 detected by the fuel pressure sensor exceeds the predetermined fuel pressure PFo. May be included.

Hereinafter, referring to FIG. 6 together with FIG. 1 and FIG. 2, the control process according to the fourth embodiment of the present invention in which the fuel discharge amount restriction execution condition includes that the fuel pressure PF exceeds the predetermined fuel pressure PFo will be described. To do.
FIG. 6 is a flowchart showing a control process of the high-pressure fuel pump 20 for automatic stop control according to the fourth embodiment of the present invention. The same processes as those described above (see FIGS. 3 to 5) are denoted by the same reference numerals. A detailed description will be omitted.

In this case, only the point that the determination process (step S413) of the fuel pressure PF is inserted instead of the determination process (step S313) of the engine rotation speed NE described above (FIG. 5) is different.
Further, the configuration of the internal combustion engine control apparatus according to Embodiment 4 of the present invention is as shown in FIGS. 1 and 2, and only the partial function of the discharge amount limiting means 632 in the ECU 60 is different.

  That is, the ECU 60 (high pressure fuel pump control device) according to Embodiment 4 of the present invention is notified of the establishment of the automatic stop condition (FS = 1) from the idle stop control means 605 in the changeover switch 635 of the discharge amount restriction means 632. And that the fuel pressure PF in the stock pressure chamber 36 detected by the fuel pressure sensor 61 exceeds the predetermined fuel pressure PFo (FS = 1 and PF> PFo). If it is, the normal contact C1 side is switched to the automatic stop control execution contact C2 side, and the fuel discharge amount of the high-pressure fuel pump 20 is controlled by the target fuel discharge amount QO limited to a predetermined amount QLMT or less.

  In FIG. 6, first, following steps S <b> 101 to S <b> 106 similar to those described above, the state of the automatic stop condition satisfaction flag FS is determined in step S <b> 107, and if it is determined that FS = 1 (the automatic stop condition is satisfied). Then, it is determined whether or not the fuel pressure PF in the animal pressure chamber 36 detected by the fuel pressure sensor 61 exceeds a predetermined fuel pressure PFo (step S413).

If it is determined in step S413 that PF> PFo (that is, Yes), the process proceeds to step S112, and the target discharge amount QO for automatic stop control limited to a predetermined amount QLMT or less as shown in the above-described equation (4). And the process proceeds to step S109.
On the other hand, if it is determined in step S413 that PF ≦ PFo (ie, No), the process proceeds to step S108, the normal target discharge amount QO (= QFB + QINJ) is calculated, and the process proceeds to step S109.
Thereafter, the above-described steps S109 to S111 are executed, and the process routine of FIG. 6 is exited.

  As a result, when both the conditions of FS = 1 in step S107 (satisfying automatic stop condition) and PF> PFo (satisfying high fuel pressure condition) in step S413 are satisfied, the condition is limited to a predetermined amount QLMT or less. Since the target fuel discharge amount QO for automatic stop control (calculated in step S112) is discharged from the high-pressure fuel pump 20 to the stock pressure chamber 36, the stock amount is limited to a level that does not affect the stop position control. The fuel in the pressure chamber 36 increases.

  On the other hand, if it is determined in step S107 that FS = 0 (automatic stop condition is not satisfied) or PF ≦ PFo (high fuel pressure condition is not satisfied) in step S413, the maximum value is not limited. Since the target fuel discharge amount QO (calculated in step S108) is discharged from the high-pressure fuel pump 20 to the livestock pressure chamber 36, the fuel in the livestock pressure chamber 36 increases by a necessary amount, and the fuel pressure PF in the livestock pressure chamber 36 increases. Coincides with the target fuel pressure PO.

As described above, according to the fourth embodiment of the present invention, when the fuel pressure PF in the stocking pressure chamber 36 of the internal combustion engine 40 heading to stop is lower than the predetermined fuel pressure PFo, the piston of the internal combustion engine 40 heading to stop. Rather than increasing the probability of stopping at an appropriate position, priority is given to securing and maintaining the fuel injection pressure and injection amount necessary for restart (during fuel injection), and the suppression of the fuel discharge amount is prohibited.
Therefore, the fuel injection pressure that overcomes the compression pressure of the air in the stop cylinder that is scheduled to combust at the time of restart, prior to limiting the fuel discharge amount before stop and stopping the piston stop position in the appropriate range The fuel pressure PF in the animal pressure chamber 36 exceeding the above can be secured, the combustion energy necessary for restarting (the amount of fuel injected from the fuel injection valve) can be secured, and a reliable automatic start can be realized. .

Note that the predetermined fuel pressure PFo determined as the condition for executing the restriction on the fuel discharge amount of the high-pressure fuel pump 20 is a value after experimental verification, and at least a cylinder (or an expansion stroke) that becomes a compression stroke when stopped. The cylinder pressure is set to a value larger than the in-cylinder pressure during stopping.
As a result, even if the fuel discharge amount before the stop is limited, the fuel injection pressure that overcomes the compression pressure of the air in the cylinder scheduled to be combusted at the time of restart is ensured at the minimum.

In addition, the internal combustion engine control apparatus according to Embodiments 1 to 4 of the present invention includes an internal combustion engine 40 having M cylinders (M is a natural number equal to or greater than “3”) and fuel injection to each of the M cylinders. The piston stroke position of the internal combustion engine 40 is provided with the high-pressure fuel pump 20 having a fuel discharge stroke N times (N is a natural number of “2” or more that satisfies “N <M”) during one round of the stroke. And a change in the load on the internal combustion engine 40 toward the stop can be suppressed without changing the configuration in which the fuel discharge position of the high-pressure fuel pump 20 has a predetermined relationship.
As a result, the piston stop position can be controlled within an appropriate range without incurring a cost increase due to the configuration change, and the combustion energy necessary for the restart can be secured to achieve a good automatic start.
Furthermore, it goes without saying that the restriction execution conditions for the fuel discharge amount described in the second to fourth embodiments can be arbitrarily combined and overlapped.

1 is a block configuration diagram schematically showing a high-pressure fuel pump control device of an internal combustion engine control device according to Embodiment 1 of the present invention. FIG. FIG. 2 is a functional block diagram specifically showing an ECU in FIG. 1. It is a flowchart which shows the control action by Embodiment 1 of this invention. It is a flowchart which shows the control action by Embodiment 2 of this invention. It is a flowchart which shows the control action by Embodiment 3 of this invention. It is a flowchart which shows the control action by Embodiment 4 of this invention. It is a timing chart for demonstrating the effect of this invention. It is a timing chart for demonstrating the conventional subject. It is a figure which shows the positional relationship of the piston stroke in a 4-cylinder internal combustion engine, and the fuel discharge stroke of a high pressure fuel pump.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow control valve, 12 Solenoid, 20 High pressure fuel pump, 36 Animal pressure chamber, 39 Fuel injection valve, 40 Internal combustion engine, 60 ECU, 61 Fuel pressure sensor, 62 Ignition switch, 63 Cam angle sensor, 64 Crank angle sensor, 65 Accelerator Position sensor, 601 target fuel pressure setting means, 602 feedback amount calculation means, 603 flow rate control valve control means, 604 internal combustion engine control means, 605 idle stop control means, 631 adder (target discharge amount calculation means), 632 discharge amount restriction means 633 Solenoid drive means, 634 Limit value calculation unit, 635 selector switch, AP accelerator pedal depression amount, NE engine speed, PF fuel pressure, PO target fuel pressure, ΔPF fuel pressure deviation, QFB fuel discharge feedback amount, QINJ fuel injection amount, QO target Charge discharge amount, TD excitation timing, FS automatic stop condition flag, FC fuel cut flag, Q lmt predetermined amount (limit value).

Claims (6)

Various sensors for detecting the operating state of the internal combustion engine;
A pressure chamber that accumulates pressurized fuel;
A fuel pressure sensor for detecting the fuel pressure in the animal pressure chamber;
A mechanical high-pressure fuel pump that discharges pressurized fuel driven by the internal combustion engine into the animal pressure chamber;
An electromagnetic flow control valve for adjusting the amount of fuel discharged from the high-pressure fuel pump to the stock pressure chamber;
The flow rate control valve is adjusted so that the fuel discharge amount of the high-pressure fuel pump becomes a necessary amount for matching the fuel pressure in the animal pressure chamber with a target fuel pressure set in advance according to the operating state of the internal combustion engine. A fuel pressure control unit to control,
A fuel injection valve for directly injecting fuel in the stock pressure chamber into the combustion chamber of the internal combustion engine;
In an internal combustion engine control device comprising:
The fuel pressure control unit has a discharge amount limiting means for limiting a fuel discharge amount of the high-pressure fuel pump to a predetermined amount or less after establishment of a stop condition of the internal combustion engine,
The internal combustion engine control apparatus according to claim 1, wherein the fuel discharge amount limiting execution condition by the discharge amount limiting means includes a predetermined period after the internal combustion engine stop condition is satisfied until the internal combustion engine is completely stopped.   2. The internal combustion engine control device according to claim 1, wherein the discharge amount limiting unit fixes a fuel discharge amount of the high-pressure fuel pump in the predetermined period to a minimum value.   The fuel discharge amount limiting execution condition by the discharge amount limiting means is after the stop condition is satisfied, and after the fuel cut control for stopping the fuel injection from the fuel injection valve is started, the internal combustion engine is The internal combustion engine control device according to claim 1, further comprising a fuel cut period until the engine is completely stopped.   The condition for executing the restriction of the fuel discharge amount by the discharge amount limiting means is after the stop condition of the internal combustion engine is satisfied, and after the engine speed of the internal combustion engine falls below a predetermined speed, the internal combustion engine is completely The internal combustion engine control device according to any one of claims 1 to 3, further comprising a low rotation speed period until the engine stops.   The fuel discharge amount limiting execution condition by the discharge amount limiting means is after the stop condition of the internal combustion engine is satisfied, and the fuel pressure detected by the fuel pressure sensor exceeds the predetermined fuel pressure. The internal combustion engine control apparatus according to any one of claims 1 to 4, wherein the internal combustion engine control apparatus includes: The internal combustion engine has M cylinders, where M is a natural number of 3 or more, and the high-pressure fuel pump has N fuel discharge strokes during one cycle of fuel injection strokes to the M cylinders. However, N has the natural number of 2 or more which satisfy | fills N <M, The internal combustion engine control apparatus of any one of Claim 1-5 characterized by the above-mentioned.

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