JP2003041981A - Start controller for cylinder injection type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sense of incongruity of a driver due to extension of starting time while shortening pressure rising time of fuel in starting. SOLUTION: An electronic control unit ECU raises pressure of the fuel by a low pressure pump in starting of the cylinder injection type internal combustion engine (steps 100 and 110). When a fuel pressure P inside a delivery pipe reaches a first predetermined value P1 after starting the pressure raising, a high pressure pump raises the fuel pressure (steps 120 and 140). When the fuel pressure P reaches a second predetermined value P2 after starting the pressure raising by the high pressure pump, fuel injection from a fuel injection valve is allowed (steps 160-180). The ECU evaluates progress of the pressure raising by each pump (steps 120, 130, 150 and 160), and when it is evaluated that the pressure raising is slow, injection timing of the fuel from the fuel injection valve is advanced (steps 140 and 190).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder injection type internal combustion engine which directly injects fuel into a cylinder, in which the pressure (fuel pressure) of the fuel is increased by a low pressure pump and a high pressure pump when the cylinder is injected. The present invention relates to a start-up control device for an internal combustion engine.

[0002]

2. Description of the Related Art For example, in a cylinder injection type internal combustion engine in which fuel is directly injected into a cylinder, it is necessary to increase the injection pressure in order to atomize the injected fuel. Therefore, the fuel in the fuel tank is driven by an electric feed pump (low pressure pump).
The fuel is pumped up, pressurized by a high-pressure pump drivingly connected to the internal combustion engine, and pressure-fed to the fuel injection valve through a high-pressure fuel pipe (delivery pipe).

In the above internal combustion engine, the high-pressure pump and the low-pressure pump also stop while the engine is stopped, so that the pressure (fuel pressure) of the fuel in the delivery pipe decreases with the passage of time. In addition, while the engine is stopped, the high temperature fuel in the delivery pipe cools and contracts, and the volume decreases. Along with this volume decrease, the fuel pressure (residual pressure) in the delivery pipe decreases. Then, if the contraction continues even if the fuel pressure drops to the atmospheric pressure, part of the fuel evaporates in an attempt to maintain the atmospheric pressure. Thus, when the engine is started, the fuel vapor may exist in the delivery pipe.

By the way, the amount of fuel discharged by the high-pressure pump is considerably smaller than the volume of the delivery pipe. Therefore, it takes a considerable amount of time to increase the pressure of the fuel whose fuel pressure has dropped to around atmospheric pressure to the required value for fuel injection. Further, when the fuel vapor exists, the delivery pipe is filled with the fuel while the fuel vapor is crushed, so that it takes more time to pressurize.

Therefore, for example, Japanese Patent Laid-Open No. 2000-5492.
No. 6, gazette discloses that the pressurizing operation of the high-pressure pump is stopped until a predetermined time elapses from the engine start, the fuel discharged from the low-pressure pump is allowed to pass through the inside of the high-pressure pump to increase the pressure, and then the high-pressure pump pressurizes. Techniques have been proposed for starting the operation and further boosting the voltage. In addition, JP-A-9-250
Japanese Patent No. 426 discloses that when the fuel pressure in the delivery pipe is lower than a predetermined value, the fuel discharged from the low-pressure pump is directly supplied to the delivery pipe, and when the fuel pressure in the delivery pipe reaches a predetermined value, the fuel discharged from the high-pressure pump is delivered to the delivery pipe. There is proposed a technique for supplying the voltage to the device to boost the voltage. With any of the above-described techniques, the fuel supply from the low-pressure pump shortens the time until the fuel pressure in the delivery pipe becomes substantially the same as the feed pressure. As a result, the time required for the fuel pressure to reach the required value for fuel injection by the fuel supply from the high-pressure pump is shortened.

[0006]

However, in the former prior art, even if the fuel is not sufficiently pressurized because the fuel vapor is not completely crushed and remains,
After a lapse of a predetermined time, the pressurizing operation of the high pressure pump is started. Further, in the latter conventional technology, since the stop of boosting by the low-pressure pump is judged by the fuel pressure, the problem as described in the former conventional technology does not occur, but if it takes time for boosting for some reason, It may take a long time to start the vehicle, and the driver may feel uncomfortable.

The present invention has been made in view of the above circumstances, and an object thereof is to shorten the fuel pressure rising time at the time of starting and to prevent the driver from feeling uncomfortable due to the extension of the starting time. It is an object of the present invention to provide a start-up control device for a cylinder injection internal combustion engine capable of performing the above.

[0008]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. In the invention according to claim 1, a low-pressure pump and a high-pressure pump that pressurizes fuel discharged from the low-pressure pump and sends the fuel under pressure to a high-pressure fuel pipe connected to a fuel injection valve of a cylinder injection internal combustion engine. A fuel pressure detecting means for detecting the pressure of the fuel in the high pressure fuel pipe; a first pressure increasing means for increasing the pressure of the fuel by the low pressure pump when the internal combustion engine is started; and a pressure increasing by the first pressure increasing means. After the start of, the second pressure increasing means for increasing the pressure of the fuel by the high pressure pump when the fuel pressure by the fuel pressure detecting means reaches a first predetermined value, and after the pressure increase by the second pressure increasing means is started, Injection permitting means for permitting fuel injection from the fuel injection valve when the fuel pressure detected by the fuel pressure detecting means reaches a second predetermined value; evaluating means for evaluating the progress of boosting by the boosting means; hand If it evaluates to boost slow, and a injection timing changing means for advancing the injection timing of fuel from the fuel injection valve has a.

According to the above arrangement, when the in-cylinder injection type internal combustion engine is started, the pressure of the fuel is boosted by the low pressure pump by the first booster. That is, the fuel discharged from the low pressure pump is supplied into the high pressure fuel pipe. By this supply, the pressure of the fuel in the high pressure fuel pipe is increased. Therefore, even if the fuel vapor exists in the high pressure fuel pipe, the fuel vapor is compressed and crushed in the process in which the fuel sent from the low pressure pump flows into the high pressure fuel pipe. Here, in order to compress the fuel vapor, it is necessary to supply a large amount of fuel, but since this supply is covered by a low-pressure pump with a larger discharge amount than the high-pressure pump, the fuel pressure in the high-pressure fuel pipe is short-lived. Thus, it becomes easy to reach the first predetermined value.

When the fuel pressure detected by the fuel pressure detection means reaches the first predetermined value after the pressure increase of the fuel is started by the first pressure increase means, the pressure increase of the fuel by the high pressure pump is executed by the second pressure increase means. Since the fuel is pumped from the high-pressure pump whose discharge pressure is higher than that of the low-pressure pump, the fuel in the high-pressure fuel pipe can easily reach the second predetermined value in a short time. When the fuel pressure detected by the fuel pressure detection means reaches the second predetermined value after the pressure increase of the fuel is started by the second pressure increase means, the fuel injection from the fuel injection valve is permitted by the injection permission means. In this case, by supplying high-pressure fuel to the fuel injection valve, the injection pressure of the fuel injection valve rises, atomization of the spray is promoted, and generation of black smoke is suppressed.

In this way, the low pressure pump shortens the time for increasing the fuel pressure to the first predetermined value,
If the time for increasing the fuel pressure from the first predetermined value to the second predetermined value by the high-pressure pump is shortened, the time required for increasing the pressure from the start to the second predetermined value is shortened as a whole. Along with this, the fuel injection timing from the fuel injection valve is also advanced.

By the way, the progress of each boosting by the first boosting means and the second boosting means is evaluated by the evaluating means. When it is evaluated that the pressure increase is slow, the injection timing of the fuel from the fuel injection valve is advanced by the injection timing changing means. That is, when the pressure increase is slow, the timing at which the fuel pressure reaches the second predetermined value may be delayed and the fuel injection timing may be delayed. In this case, it is evaluated that the boosting is slow, the injection timing is advanced, and the fuel is injected before the fuel pressure reaches the second predetermined value.

Therefore, in the process in which the boosting time is shortened by the boosting means as described above, when the boosting takes a long time and the starting time itself is prolonged, the starting is prioritized. . As a result, it is possible to prevent the driver from feeling uncomfortable due to the extension of the starting time.

According to a second aspect of the present invention, in the first aspect of the present invention, the evaluation means is based on the elapsed time after the starter for starting the internal combustion engine starts operating and the fuel pressure detection means. The progress of the boosting is evaluated based on the fuel pressure.

According to the above arrangement, the evaluation means evaluates the progress of boosting based on the elapsed time from the start of the operation of the starter and the fuel pressure detected by the fuel pressure detection means. For example, if the fuel pressure does not reach a desired value even after a certain amount of time has passed after the start of the operation of the starter, it is evaluated that the boosting is slow.

According to a third aspect of the present invention, in the second aspect of the present invention, the evaluation means is such that when the elapsed time reaches a first set value, the fuel pressure detected by the fuel pressure detection means is equal to the first set value. When the predetermined value of 1 is not reached, it is evaluated that the boosting is slow, and the injection timing changing means starts the boosting by the second boosting means when the evaluation means evaluates that the boosting is slow. is there.

According to the above arrangement, the evaluation means determines whether the fuel pressure detected by the fuel pressure detection means reaches the first predetermined value at the time when the elapsed time after the start of the operation of the starter reaches the first set value. Based on, the progress of boosting is evaluated. If the fuel pressure does not reach the first predetermined value even after the elapsed time reaches the first set value, and the fuel pressure reaches the first predetermined value when the first pressure increasing means continues to increase the pressure as it is. Behind time. Along with that, the fuel pressure is the second
Since it is considered that the timing of reaching the predetermined value of or the fuel injection timing is delayed, it is evaluated that the boosting is slow.

In this case, in the injection timing changing means,
Boosting by the second boosting means is forcibly started. That is, even if the fuel pressure does not reach the first predetermined value, if a certain amount of time elapses (when the elapsed time reaches the first set value), the first pressure increasing means changes the pressure increase to the second pressure increasing means. Forcibly switched to boost. By this switching, the fuel injection timing can be advanced as compared with the case where the boosting by the first booster is continued.

The invention according to claim 4 is the invention according to claim 2 or 3.
In the invention described in (1), the evaluation means evaluates that the boosting is slow when the elapsed time reaches the second set value and the fuel pressure by the fuel pressure detection means does not reach the second predetermined value. However, when the boosting is evaluated to be slow by the evaluating means, the injection timing changing means suspends boosting by the second boosting means and performs fuel injection at a low fuel pressure by only the first boosting means. It is supposed to permit that.

With the above arrangement, the evaluation means determines whether the fuel pressure detected by the fuel pressure detection means reaches the second predetermined value at the time when the elapsed time after the start of the operation of the starter reaches the second set value. Based on, the progress of boosting is evaluated. If the fuel pressure does not reach the second predetermined value even after the elapsed time reaches the second set value, and if the second booster continues to boost the fuel pressure as it is, the fuel pressure usually reaches the second predetermined value. Behind time. Accordingly, the injection timing is considered to be delayed, so that the boosting is evaluated to be slow.

In this case, in the injection timing changing means,
The boosting by the second boosting means is forcibly stopped. That is, even if the fuel pressure does not reach the second predetermined value, after a certain amount of time has elapsed (when the elapsed time reaches the second set value), the boosting by the second boosting means is ended. Then, the fuel injection at a low fuel pressure is performed only by the first booster. In this way, the fuel injection timing can be made earlier than when the boosting by the second boosting means is continued.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a starting control device for a cylinder injection type multi-cylinder gasoline engine (hereinafter, simply referred to as an engine) will be described with reference to the drawings.

As shown in FIG. 1, a delivery pipe 12, which is a common high-pressure fuel pipe, is connected to the fuel injection valve 11 provided for each cylinder of the engine, and the fuel in the delivery pipe 12 is supplied to each fuel pipe. It is distributed and supplied to the fuel injection valve 11. Each fuel injection valve 11 is controlled to open and close to directly inject and supply high-pressure fuel to the combustion chamber of the corresponding cylinder. The injected fuel mixes with the air in the combustion chamber to form an air-fuel mixture. The delivery pipe 12 has a means for detecting the pressure of fuel inside (hereinafter referred to as fuel pressure).
A fuel pressure sensor 13 is attached.

The engine is provided with a starter (not shown) for imparting a rotational force to the crankshaft by cranking when the engine is started. This starter
It operates according to the operation of the ignition switch (not shown) by the driver. That is, the ignition switch
As is well known, it is movable between an off position and an on position, and between the on position and the start position. The starter is operated while the ignition switch is operated from the on position to the start position.

The fuel supply device 14 for supplying high-pressure fuel to the delivery pipe 12 comprises a low-pressure pump 15 and a high-pressure pump 16. The low-pressure pump 15 is arranged in a fuel tank 17 that stores fuel (gasoline), and is driven by an electric motor (not shown) that uses a battery as a power source. In the present embodiment, the low-pressure pump 15 starts its operation when the ignition switch is operated from the off position to the on position, and stops when it is operated from the on position to the off position. The low pressure pump 15 is connected to the high pressure pump 16 by a low pressure fuel passage 18. Low pressure pump 1
Reference numeral 5 sucks fuel from the fuel tank 17 and discharges the fuel toward the high-pressure pump 16. The low-pressure pump 15 is characterized by a large discharge amount and a low discharge pressure. Further, since it is driven by an electric motor, there is a feature that the discharge characteristic of the low-pressure pump 15 at the time of starting the engine is not affected by the rotation fluctuation of the engine. A pressure regulator 19 for maintaining the pressure (feed pressure) in the low-pressure fuel passage 18 constant, for example, 0.4 MPa (megapascal), is provided in the middle of the low-pressure fuel passage 18.

The high pressure pump 16 comprises a plunger 21, a pressurizing chamber 22 and an electromagnetic spill valve 23. Plunger 2
1 reciprocates in the cylinder 26 based on the rotation of the cam 25 attached to the camshaft 24 (or crankshaft) of the engine. Therefore, the operation start timing of the plunger 21 is the same as the start timing of the camshaft 24, that is, the start timing of the starter when the ignition switch is operated from the on position to the start position.

The pressurizing chamber 22 is partitioned by the cylinder 26 and the plunger 21, and the low-pressure fuel passage 18 described above is connected to the pressurizing chamber 22. In the pressurizing chamber 22, the fuel suction port 2 is connected to the low pressure fuel passage 18.
2a. The pressurizing chamber 22 is connected to the delivery pipe 12 by a high pressure fuel passage 27. A check valve 28 for preventing the reverse flow of the fuel discharged from the high pressure pump 16 is provided in the middle of the high pressure fuel passage 27.

The electromagnetic spill valve 23 is used as a fuel pressure control valve for opening and closing the fuel intake port 22a of the pressurizing chamber 22. The electromagnetic spill valve 23 includes an electromagnetic solenoid 29, and is opened / closed by controlling energization of the solenoid 29. When the energization of the electromagnetic solenoid 29 is stopped, the electromagnetic spill valve 23 is opened by the spring 31. That is, the fuel suction port 22a is opened, and the low pressure fuel passage 18 and the pressurizing chamber 22 are in communication with each other. In this state, the direction in which the volume of the pressurizing chamber 22 increases (downward in FIG. 1)
When the plunger 21 moves (during the suction stroke),
The fuel delivered from the low-pressure pump 15 is the low-pressure fuel passage 1
8 is sucked into the pressurizing chamber 22.

When the plunger 21 moves in the direction in which the volume of the pressurizing chamber 22 contracts (upward in FIG. 1) (during the pressure feeding process), the electromagnetic spill valve 23 causes the spring 31 to move by energizing the electromagnetic solenoid 29. It is closed against.
That is, the fuel suction port 22a is closed and the communication between the low pressure fuel passage 18 and the pressurizing chamber 22 is cut off. With the movement of the plunger 21, the fuel pressure in the pressurizing chamber 22 rises and the check valve 28 is opened, so that the fuel is discharged into the delivery pipe 12 through the high-pressure fuel passage 27.

The amount of fuel discharged from the high-pressure pump 16 is adjusted by controlling the closing timing of the electromagnetic spill valve 23.
It is performed by adjusting the valve closing period of the electromagnetic spill valve 23 during the pressure feeding process. That is, if the valve closing start time of the electromagnetic spill valve 23 is advanced and the valve closing period is lengthened, the fuel discharge amount increases. On the contrary, when the closing timing of the electromagnetic spill valve 23 is delayed to shorten the valve closing period, the fuel discharge amount decreases. Then, the delivery pipe 12 is adjusted by adjusting the fuel discharge amount of the high-pressure pump 16 as described above.
The fuel pressure inside is controlled.

In this embodiment, the engine is a 6-cylinder engine, and the high-pressure pump 16 pumps fuel three times for two rotations of the crankshaft. That is, the high-pressure pump 16 pressure-feeds the fuel once for the two fuel injections in the two cylinders of the engine. The high-pressure pump 16 configured as described above has a smaller fuel discharge amount than the low-pressure pump 15 (a few tenths of the discharge amount of the low-pressure pump 15), but has a higher discharge pressure than the low-pressure pump 15. It is characterized by being several tens of times the discharge pressure of the low-pressure pump 15.

The delivery pipe 12 has a check valve 32.
And communicates with the low-pressure fuel passage 18 via. Then, if the fuel pressure in the delivery pipe 12 becomes excessively high,
The check valve 32 opens and the high-pressure fuel in the delivery pipe 12 flows out to the low-pressure fuel passage 18. In this way, the fuel pressure in the low-pressure fuel passage 18 into which the fuel flows is maintained at a constant pressure by the pressure regulator 19 as described above. Therefore, the check valve 32 and the pressure regulator 19 are
As a result, the fuel pressure in the delivery pipe 12 is suppressed from becoming excessively high.

An electronic control unit (hereinafter referred to as “ECU”) 33 is provided to control the injection amount and injection timing of fuel from the fuel injection valve 11 and the energization of the electromagnetic spill valve 23. The ECU 33 is mainly configured by a microcomputer, and a central processing unit (CPU) performs arithmetic processing according to a control program and initial data stored in a read-only memory (ROM), and various controls are performed based on the arithmetic result. To execute. The calculation result by the CPU is temporarily stored in the random access memory (RAM).

The ECU 33 uses, for example, an engine speed,
It reads the detection signals of various sensors that detect the operating state of the engine, such as the intake pipe pressure (or intake air amount) and cooling water temperature, calculates the fuel injection amount and injection timing, and outputs the injection signal according to the calculation result. Output to the injection valve 11 to execute fuel injection. The ECU 33 also performs control for increasing the pressure of fuel when the engine is started. This control promotes atomization of the spray by increasing the fuel injection pressure at the start,
Therefore, it is performed in order to reduce the injection amount at the time of starting and reduce the generation of black smoke.

Next, the contents of this starting control will be described with reference to the flowchart of FIG. The electromagnetic spill valve 23 of the high-pressure pump 16 is open before the engine is started.

In step 100, it is determined whether or not the driver has operated the ignition switch (IG) from the off position to the on position to start the engine.
If this determination condition is not satisfied, the startup control routine is once terminated, and if it is satisfied, the electric motor is energized in step 110 to operate the low-pressure pump 15. By this operation, the low-pressure pump 15 pumps up fuel from the fuel tank 17, pressurizes it, and discharges it. At this time, since the electromagnetic spill valve 23 is open, the fuel discharged from the low-pressure pump 15 passes through the inside of the high-pressure pump 16 (pressurization chamber 22 and the like) and is directly sent to the delivery pipe 12 under pressure. Due to the fuel supplied from the low-pressure pump 15, the fuel pressure P in the delivery pipe 12 gradually changes (increases).

When the ignition switch is operated from the on position to the start position, the starter operates and cranking is started. Along with this, the plunger 21 of the high-pressure pump 16 reciprocates. However, the electromagnetic spill valve 23
Is opened, the pressurization operation is stopped in the high-pressure pump 16, and the fuel is not pressurized in the pressurization chamber 22. The fuel discharged from the low pressure pump 15 continues to be the high pressure pump 16
It is supplied to the delivery pipe 12 through the inside of the delivery pipe.
At this time, the amount of fuel sent to the delivery pipe 12 is larger than that when the high-pressure pump 16 performs the pressurizing operation, so that the delivery pipe 12 is filled with the fuel in a short time and the fuel pressure P
Rises early. Further, when the fuel vapor is present in the delivery pipe 12 when the engine is started, it is compressed and crushed early by the fuel from the low pressure pump 15.

Next, at step 120, it is judged if the fuel pressure P detected by the fuel pressure sensor 13 is greater than or equal to a first predetermined value P1. Here, when the fuel from the low-pressure pump 15 passes through the high-pressure pump 16 and the feed pressure acts on the delivery pipe 12 as it is, the fuel pressure becomes lower than the feed pressure as long as the fuel vapor exists. . The fuel pressure P increases as the fuel vapor is crushed. When the fuel pressure is equal to or higher than the feed pressure, it is considered that the fuel vapor is completely crushed. Therefore, the first
The predetermined value P1 of the feed pressure of the low-pressure pump 15 (0.4M
Pa) or more. However, the fuel pressure sensor 13
It is preferable that the first predetermined value P1 is set to a value larger than the feed pressure (for example, 1.0 MPa) in consideration of the variation of

If the determination condition of step 120 is satisfied (P ≧ P1), the process proceeds to step 140, and if it is not satisfied (P <P1), the process proceeds to step 130. In step 130, it is determined whether or not a first set time T1 (for example, 300 milliseconds) has elapsed since the ignition switch was operated to the start position, that is, after the starter started to operate. In this way, it is determined whether or not the elapsed time from the start of operation of the starter has reached the first set value (first set time T1).

If the determination condition of step 130 is not satisfied (first set time T1 has not elapsed), the start-up control routine is once ended and is satisfied (first set time T1).
(Elapsed) and the process proceeds to the next step 140. in this way,
If the determination condition of step 130 is satisfied, that is, if the first set time T1 has elapsed after the start of the operation of the starter, even if the determination result of step 120 is not satisfied (P <P1 ) Go to the next Step 140.

In step 140, the electromagnetic solenoid 29
The pressurizing operation of the high-pressure pump 16 is started by controlling the energization of the high-pressure pump 16. The reciprocating movement of the plunger 21 pressurizes the fuel in the pressurizing chamber 22. With the start of this pressurizing operation, high-pressure fuel is pressure-fed to the delivery pipe 12 little by little. The discharge pressure of the high pressure pump 16 is the low pressure pump 15.
Since the discharge pressure is higher than the discharge pressure, the fuel pressure P reaches a higher pressure than when the low pressure pump 15 boosts the pressure.

As described above, steps 120 and 130
Then, based on the elapsed time from the start of the operation of the starter and the fuel pressure P from the fuel pressure sensor 13, the progress of the boosting of fuel by the low pressure pump 15 is evaluated. Specifically, it is evaluated that the boosting is slow when the fuel pressure P does not reach the first predetermined value P1 at the time when the first set time T1 has elapsed since the starter started to operate. In this case, the pressure increase by the high pressure pump 16 is forcibly started.

Next, in step 150, the second set time T2 has elapsed since the ignition switch was operated to the start position, that is, after the starter started operating.
It is determined whether (for example, 500 milliseconds) has elapsed. In this way, it is determined whether the elapsed time from the start of the starter operation has reached the second set value (second set time T2).

If the determination condition of step 150 is not satisfied, the startup control routine is once terminated, and if it is satisfied, in step 160, the fuel pressure P detected by the fuel pressure sensor 13 is the second predetermined value P2 (for example, , 1.5
MPa) or more.

When the judgment condition of step 160 is satisfied, it is judged in step 170 whether or not a predetermined injection start condition is satisfied. In the present embodiment, for example, the following three conditions (a) to (c) are set, and the injection start condition is satisfied when one of these conditions is satisfied. The condition (a) is “the fuel pressure P is equal to or higher than a third predetermined value P3”. The third predetermined value P3 is larger than the above-mentioned second predetermined value P2, and 6 MPa is set here. The condition (b) is “the number of times the high-pressure pump 16 is fed under pressure is a predetermined value, for example,“ 3 ”or more”. The condition (c) is "the third set time T3 has elapsed since the start of the operation of the starter". The third set time T3 is a value larger than the second set time T2, and is set to 600 milliseconds here.

If the injection start condition is satisfied in step 170, the fuel injection valve 11 is opened by energizing the fuel injection valve 11 in step 180. With this opening, the fuel injection valve 11
The high-pressure fuel is directly injected and supplied from the to the corresponding combustion chamber.
On the other hand, when the injection start condition is not satisfied in step 170, and after the processing of step 180 has been performed, the startup control routine ends.

In this way, when the fuel pressure P reaches the second predetermined value P2 after the boosting by the high pressure pump 16 is started,
High-pressure fuel injection from the fuel injection valve 11 is permitted provided that the injection start condition in step 170 is satisfied.

On the other hand, if the determination condition of step 160 is not satisfied (P <P2), the electromagnetic spill valve 23 is opened by stopping the energization of the electromagnetic solenoid 29 in step 190. By this valve opening, the pressurization of fuel in the pressurizing chamber 22 is stopped, and the fuel discharged from the low-pressure pump 15 passes through the interior of the high-pressure pump 16 and is pumped to the delivery pipe 12. .
Then, in step 200, by energizing the fuel injection valve 11, the fuel injection valve 11 is opened. With this opening, the pressure (feed pressure) lower than that in step 180 is applied to the corresponding combustion chamber from the fuel injection valve 11.
The fuel is directly injected and supplied.

As described above, steps 150 and 160
Then, based on the elapsed time from the start of the operation of the starter and the fuel pressure P from the fuel pressure sensor 13, the progress of the boosting of fuel by the high pressure pump 16 is evaluated. Specifically, it is evaluated that the boosting is slow when the fuel pressure P does not reach the second predetermined value P2 at the time when the second set time T2 has elapsed since the starter started to operate. Then, in this case, the electromagnetic spill valve 23 is opened to forcibly stop the pressure increase by the high pressure pump 16 (step 190), and fuel injection is performed at a low fuel pressure of only the low pressure pump 15 (step). 200).

According to this embodiment described in detail above, the following effects can be obtained. (1) It is necessary to supply a large amount of fuel in order to compress and crush the fuel vapor existing in the delivery pipe 12 when the engine is started. If this is attempted to be corrected by only the high-pressure pump 16 having a small discharge amount, it takes a long time. On the other hand, in the present embodiment, after the ignition switch is operated to the ON position, the pressurization operation by the high pressure pump 16 is stopped until the fuel pressure P reaches the first predetermined value P1. Due to this stopping of the pressurization operation, the entire amount of fuel discharged from the low-pressure pump 15 is reduced to the delivery pipe 12.
A large amount of fuel required for compression of the fuel vapor is sent to the low pressure pump 15 with a large discharge amount (tens of times that of the high pressure pump 16).
Will be covered by. Therefore, the delivery pipe 12 can be filled with fuel while crushing the fuel vapor in a shorter time than when the fuel is pressure-fed by the high-pressure pump 16. After operating the ignition switch to the ON position, the fuel vapor can be compressed in a short time to quickly increase the fuel pressure P to the first predetermined value P1.

(2) When the fuel pressure P exceeds the first predetermined value P1, the pressurizing operation of the high pressure pump 16 is started to increase the pressure of the fuel (step 140). With no fuel vapor in the delivery pipe 12, the low-pressure pump 15
Since the fuel is pressure-fed from the high-pressure pump 16 having a higher discharge pressure than that, the fuel in the delivery pipe 12 can be boosted to the second predetermined value P2 in a short time.

(3) As described in (1) and (2) above, the fuel pressure P is set to the first predetermined value P by the low pressure pump 15.
High pressure pump 16
The fuel pressure P from the first predetermined value P1 to the second predetermined value P
Since the time for increasing the pressure to 2 can be shortened, the fuel pressure P is the second predetermined value P2 from the start of the operation of the starter.
It is possible to shorten the boosting time until.

(4) When the fuel pressure P reaches the second predetermined value P2, the high-pressure fuel injection from the fuel injection valve 11 is permitted under the condition that the injection start condition is satisfied (step). 160-180). In this case, since the high-pressure fuel is supplied to the fuel injection valve 11, the injection pressure of the fuel injection valve 11 rises, so atomization of the spray can be promoted and generation of black smoke can be suppressed.

(5) When the fuel pressure P has not reached the first predetermined value P1 even though the first set time T1 has elapsed since the start of the operation of the starter, the low pressure pump 1 remains as it is.
If the boosting by 5 is continued, the fuel pressure P becomes the first predetermined value P.
The timing to reach 1 is delayed compared to the normal time. Along with this, it is considered that the timing at which the fuel pressure P reaches the second predetermined value P2 and the fuel injection timing are delayed, so that it is evaluated that the boosting is slow. Then, in the case of this evaluation, the pressurization by the high-pressure pump 16 is forcibly started (steps 120 to 14).
0).

Therefore, even if the fuel pressure P does not reach the first predetermined value P1, after a certain amount of time has passed (when the first set time T1 has passed), the pressure increase from the low pressure pump 15 to the high pressure pump 16 is increased. Is forced to switch to. By this switching, the fuel injection timing can be advanced as compared with the case where the pressure increase by the low pressure pump 15 is continued.

(6) When the fuel pressure P does not reach the second predetermined value P2 despite the elapse of the second set time T2 from the start of the operation of the starter, the high pressure pump 1 remains as it is.
If the boosting by 6 is continued, the fuel pressure P becomes the second predetermined value P.
The timing to reach 2 is delayed compared to the normal time. Along with this, it is considered that the injection timing will be delayed, so it is evaluated that the boosting is slow. Then, in the case of this evaluation, the boosting by the high-pressure pump 16 is forcibly stopped (steps 150, 160,
190).

Therefore, even if the fuel pressure P does not reach the second predetermined value P2, after a certain amount of time has passed (when the second set time T2 has passed), boosting by the high-pressure pump 16 is terminated. Then, the fuel is injected at a low fuel pressure only by the low pressure pump 15 (step 200). In this way, the fuel injection timing can be advanced as compared with the case where the pressure increase by the high pressure pump 16 is continued.

(7) At the time of starting the engine, basically, the boosting time is shortened as described in (3) above. However, in this process, it takes time to boost the pressure and the starting time itself is shortened. If it is extended, please refer to (5) above.
As described in (6) and (6), the start is prioritized by advancing the fuel injection timing.
As a result, it is possible to prevent the driver from feeling uncomfortable due to the extension of the starting time.

(8) The high-pressure pump 16 is provided with a pressurizing chamber 22 having a fuel inlet 22a and an electromagnetic spill valve 23 for opening and closing the fuel inlet 22a. The electromagnetic spill valve 23 is kept open when the pressurizing operation is stopped. Therefore, by controlling the energization of the electromagnetic solenoid 29, the electromagnetic spill valve 23 is maintained in the open state, the pressurizing operation of the high-pressure pump 16 is stopped, and the fuel from the low-pressure pump 15 is reliably transferred to the delivery pipe 12. Can be supplied to.

The present invention can be embodied in another embodiment shown below. The present invention can also be applied to the fuel supply device 14 of the type in which the operation of the low pressure pump 15 is started on condition that the ignition switch is operated to the start position.

As the determination condition of step 120, the following conditions (i) and (ii) may be added to "the fuel pressure P is equal to or higher than the first predetermined value P1". These conditions (i) and (ii) are for determining whether or not the fuel vapor has been crushed by the compression.

(I) The differential pressure from the fuel pressure before the low-pressure pump 15 is activated (initial fuel pressure) is a predetermined value (for example, 0.3 MPa).
That is all. That is, the fuel pressure has increased by a predetermined value or more due to the operation of the low-pressure pump 15. This is because if the fuel vapor is compressed by the fuel from the low pressure pump 15,
The fuel pressure in the delivery pipe 12 should change (increase). Then, this fuel pressure increases as the amount of fuel discharged from the low-pressure pump 15 increases. Therefore, the low pressure pump 15
If the fuel pressure changes to some extent after the start of
This is because it is considered that the fuel vapor has been crushed if the differential pressure before and after the operation of the low-pressure pump 15 exceeds a predetermined value.

(Ii) A predetermined time (for example, 400 milliseconds) has elapsed since the ignition switch was operated to the ON position. That is, the low-pressure pump 15 starts operating in accordance with the operation of the ignition switch to the ON position, and supplies fuel to the delivery pipe 12. The amount of time that has elapsed from the start of the operation of the low-pressure pump 15 is determined in advance by experiments or the like to determine the fuel pressure P in the delivery pipe 12 up to the feed pressure, and this is set as the above-mentioned predetermined time.

If "the fuel pressure P is equal to or higher than the first predetermined value P1" and any of the conditions (i) and (ii) is satisfied, it is determined that the determination condition of step 120 is satisfied (affirmative). (Determination), and the process proceeds to the next step 140.

The fuel pressure sensor 13 is connected to the delivery pipe 12
Alternatively, the high-pressure fuel passage 27 may be provided on the downstream side of the check valve 28. In the above embodiment, the return pipe is not provided with a relief passage between the delivery pipe 12 and the fuel tank 17 on the fuel supply side.
A relief passage (return passage) having a relief valve may be provided between the fuel tank 17 and the fuel tank 17. With this configuration, when the fuel pressure P in the delivery pipe 12 rises to a predetermined fuel pressure or higher, the fuel in the delivery pipe 12 can be returned to the fuel tank 17 via the relief passage.

In the above embodiment, the electromagnetic spill valve 23 of the type in which the fuel sucked into the pressurizing chamber 22 overflows is used as the fuel pressure control valve, but the fuel sucked into the pressurizing chamber 22 is controlled. A metering type intake metering valve may be used as the fuel pressure control valve.

In the above embodiment, the low-pressure pump 15 is an electric pump, but the low-pressure pump 15 may be, for example, a mechanical pump that is auxiliary driven by a starter when the engine is started. .

In the above embodiment, the high pressure pump 16
When the pressurizing operation of 1 is stopped and the fuel vapor is compressed, the driving voltage of the low-pressure pump 15 may be increased to increase the discharge amount. By doing so, the compression of the fuel vapor by the low-pressure pump 15 can be performed more efficiently. Also,
A preliminary pump may be provided and used in combination with the low pressure pump 15 to increase the discharge amount when the fuel vapor is compressed. In this case, the same effect can be obtained.

The present invention is applicable not only to a gasoline engine as long as it is a cylinder injection type internal combustion engine, but also to a diesel engine, for example. In addition, technical ideas that can be understood from each of the above-described embodiments will be described together with their effects.

(A) In the startup control device for a cylinder injection type internal combustion engine according to any one of claims 1 to 4, the low pressure pump is driven by an electric motor.
According to the above configuration, the discharge characteristic of the low-pressure pump at the time of starting the internal combustion engine does not have to be affected by the rotational fluctuation of the internal combustion engine.

(B) In the startup control device for a cylinder injection type internal combustion engine according to any one of claims 1 to 4, the high pressure pump includes a fuel pressure control valve for opening and closing a fuel intake port thereof, The fuel pressure control valve is maintained in an open state when the pressurizing operation is stopped.

According to the above construction, by maintaining the fuel pressure control valve in the open state, the pressurizing operation of the high pressure pump can be stopped and the fuel from the low pressure pump can be reliably supplied to the high pressure fuel pipe. it can.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of an embodiment of a start-up control device for a direct injection internal combustion engine according to the present invention.

FIG. 2 is a flowchart showing a procedure of control performed at the time of starting.

[Explanation of symbols]

11 ... Fuel injection valve, 12 ... Delivery pipe (high pressure fuel pipe), 13 ... Fuel pressure sensor (fuel pressure detection means), 15 ... Low pressure pump, 16 ... High pressure pump, 33 ... ECU (electronic control unit).

Continued front page    (72) Inventor Motoki Otani             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F-term (reference) 3G301 HA04 HA06 JA03 JA12 JA23                       KA01 LB04 LB07 LB13 LB16                       MA11 MA18 MA28 NA08 ND02                       NE23 PA07Z PB03A PB03Z                       PB05A PB05Z PB08A PB08Z                       PE01Z PE08Z PF16Z

Claims (4)

[Claims] 1. A low-pressure pump, a high-pressure pump for pressurizing fuel discharged from the low-pressure pump, and pumping the fuel to a high-pressure fuel pipe connected to a fuel injection valve of a cylinder injection type internal combustion engine; Fuel pressure detecting means for detecting the pressure of the fuel in the fuel pipe; first boosting means for boosting the fuel by the low pressure pump when the internal combustion engine is started; and after starting boosting by the first boosting means, Second boosting means for boosting the fuel by the high-pressure pump when the fuel pressure by the fuel pressure detecting means reaches a first predetermined value; and the fuel pressure detecting means after the boosting by the second boosting means is started. Injection permission means for permitting fuel injection from the fuel injection valve when the fuel pressure by the fuel injection method reaches a second predetermined value, evaluation means for evaluating the progress of boosting by each boosting means, An in-cylinder injection internal-combustion-engine start-up control device comprising: an injection timing changing unit that advances the injection timing of fuel from the fuel injection valve when the pressure is evaluated to be slow. 2. The evaluation means evaluates the progress of the boosting based on the elapsed time after the starter of the internal combustion engine has started to operate and the fuel pressure detected by the fuel pressure detection means. Of the in-cylinder injection internal combustion engine at startup. 3. The evaluation means evaluates that the boosting is slow when the elapsed time reaches a first set value and the fuel pressure detected by the fuel pressure detection means has not reached the first predetermined value. The startup control device for a cylinder injection internal combustion engine according to claim 2, wherein the injection timing changing unit starts the boosting by the second boosting unit when the boosting is evaluated to be slow by the evaluating unit. 4. The evaluation means evaluates that the boosting is slow when the elapsed time reaches a second set value and the fuel pressure detected by the fuel pressure detection means has not reached the second predetermined value. The injection timing changing means stops the boosting by the second boosting means and performs fuel injection at a low fuel pressure only by the first boosting means when the boosting is evaluated to be slow by the evaluating means. The control device at the time of starting the in-cylinder injection type internal combustion engine according to claim 2 or 3, which permits the above.