JP2006188972A - Starting time control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a starting time control device of an internal combustion engine suitable for imparting a superior starting characteristic to the internal combustion engine, in the starting time control device of the internal combustion engine. <P>SOLUTION: After beginning starting of the internal combustion engine, fuel pressure in a delivery pipe is increased by force feed of a high pressure pump (Figure (F)). Fuel injection of a first time is performed in the time t2 after the fuel pressure becomes predetermined pressure A or more. When determining that an initial explosion is not caused in the time t3, an injection quantity, the ignition timing and the injection timing being a parameter on the initial explosion are changed (Figure (I), (K), (J)). A determination of the initial explosion is made by whether or not time et30 required for rotating a crankshaft by 30° is less than a predetermined value B or less (Figure (B)). The fuel injection and ignition of a second time are performed in the time t4 on the basis of the changed parameter. When determining that the initial explosion is caused in the time t5, the parameter is changed in the time t6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a start-time control device for an internal combustion engine, and more particularly to a start-time control device suitable for giving good start characteristics to an internal combustion engine.

  Conventionally, for example, Japanese Patent Application Laid-Open No. 7-286539 discloses an apparatus for detecting an initial explosion based on a rate of increase in engine speed when starting an internal combustion engine. In this device, different fuel injection timings are used for the period from the first explosion to the period from the first explosion to the complete explosion and the period from the complete explosion.

JP-A-7-286539 JP-A-2-146240 JP 2002-188490 A

However, when there is no initial explosion in the first fuel injection due to the influence of the properties of the fuel and the like, there is a problem that even if the second fuel injection is performed under the same conditions as the first, the first explosion is unlikely to occur. For this reason, there was a problem that the initial explosion could not be performed reliably and the starting characteristics of the internal combustion engine were deteriorated.
On the other hand, if the first fuel injection is performed with an injection amount that is expected to cause the first explosion, there is a problem that emissions of HC and the like increase.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a start-up control device for an internal combustion engine having good starting characteristics.

In order to achieve the above object, a first invention is a fuel injection valve that injects fuel into an internal combustion engine;
Initial explosion determination means for determining whether or not an initial explosion has occurred in the internal combustion engine;
First explosion parameter setting means for setting parameters for the first explosion,
And an initial explosion parameter changing means for changing the parameter when the initial explosion does not occur with the parameter.

The second invention is the first invention, wherein
The parameter includes at least one of a fuel injection amount, a fuel injection timing, and an ignition timing.

The third invention is the first or second invention, wherein
The initial explosion determining means determines the initial explosion based on a change in time required for the crankshaft to rotate by a predetermined angle.

  According to the first invention, the first explosion can be reliably performed by changing the parameters.

  According to the second aspect of the invention, the first explosion can be reliably performed by changing at least one of the injection amount, the injection timing, and the ignition timing.

  According to the third invention, the presence or absence of the first explosion can be determined instantaneously by determining the initial explosion based on the change in the time required for the crankshaft to rotate by a predetermined angle.

[Description of system configuration]
FIG. 1 is a diagram for explaining a system configuration according to an embodiment of the present invention. As shown in FIG. 1, the system according to the present embodiment includes a fuel injection valve 10. The fuel injection valve 10 is configured to directly inject high-pressure fuel into a cylinder (not shown). In the system of the present embodiment, the internal combustion engine has four cylinders. Four fuel injection valves 10 are provided corresponding to the four cylinders. The four fuel injection valves 10 are connected to a common delivery pipe 11.

  A fuel pressure sensor 12 is provided at one end of the delivery pipe 11. The fuel pressure sensor 12 detects the pressure of the fuel in the delivery pipe 11. The other end of the delivery pipe 11 is connected to the high pressure pump 20 via the high pressure fuel passage 14. A check valve 13 is provided in the high-pressure fuel passage 14. The check valve 13 is configured to open when the fuel pressure in the high-pressure fuel passage 14 exceeds a predetermined value.

  The high pressure pump 20 includes a plunger 22. The plunger 22 is configured to reciprocate in the vertical direction within the cylinder 21. The lower end of the plunger 22 is in contact with the cam 25. The cam 25 has two cam peaks. The cam 25 is provided on the intake or exhaust camshaft 24. The camshaft 24 is connected to the crankshaft by a connecting mechanism such as a timing belt. A crank angle sensor 41 is provided on the crankshaft. The crank angle sensor 41 is configured to generate a pulse signal as the crankshaft rotates.

  The delivery pipe 11 is connected to the low pressure fuel passage 33 via the check valve 34. The check valve 34 is configured to open and release the pressure when the inside of the delivery pipe 11 becomes too high. The end of the low pressure fuel passage 33 is connected to the fuel tank 30. The low pressure fuel passage 33 is connected to the high pressure pump 20. A spill valve 35 is provided in the low pressure fuel passage 33. The spill valve 35 is configured to communicate or block between the fuel tank 30 and the high-pressure pump 20.

  A feed pump 31 and a regulator 32 are provided in the fuel tank 30. The feed pump 31 is configured to send the fuel stored in the fuel tank 30 to the low pressure fuel passage 33 at a low pressure. The regulator 32 is configured to keep the fuel pressure in the low-pressure fuel passage 33 constant.

The system shown in FIG. 1 includes a water temperature sensor 42 and a starter motor 43. The water temperature sensor 42 is configured to output an electrical signal in accordance with the temperature of the cooling water of the internal combustion engine. The starter motor 43 is configured to rotate the crankshaft when starting the internal combustion engine.
In addition, the system shown in FIG. 1 includes a spark plug 15 that ignites the fuel supplied into the cylinder. In this system, four spark plugs are provided corresponding to the four cylinders.

  Further, the system shown in FIG. 1 includes an ECU (Electronic Control Unit) 50. The ECU 50 is connected to the various sensors, pumps, and valves described above. The ECU 50 can execute start-up control of the internal combustion engine based on the sensor outputs. More specifically, the ECU 50 can calculate the time et30 required for the crankshaft to rotate by 30 ° from the pulse output signal of the crank angle sensor 41. Further, the ECU 50 can determine whether or not the initial explosion has occurred by comparing the calculated time et30 with a predetermined value. Further, the ECU 50 stores parameters relating to the first explosion. The ECU 50 can change the parameters relating to the first explosion when the first explosion does not occur despite the fuel injection. Details of processing executed by these ECUs 50 will be described later.

[System Operation]
Next, the operation of the above-described system will be briefly described.
When the starter motor 43 is turned on, the operation of the feed pump 31 starts. Thereby, the fuel is sent from the fuel tank 30 to the high-pressure pump 20 at a low pressure. When the starter motor 43 is turned on, the crankshaft rotates and the camshaft 24 connected to the crankshaft rotates. As a result, fuel is pumped from the high-pressure pump 20 to the delivery pipe 11.

When the fuel pressure in the delivery pipe 11 becomes equal to or higher than a predetermined pressure, fuel injection from the fuel injection valve 10 into the cylinder is started. Thereafter, the injected fuel is ignited by the spark plug 15.
In the system according to the present embodiment, fuel injection and ignition are sequentially performed on the four cylinders while the crankshaft rotates 720 °. That is, every time the crankshaft rotates 180 °, fuel injection and ignition are performed on different cylinders.

Next, combustion injection and ignition control at the start of the internal combustion engine will be described.
First, with reference to FIG. 2, start-up control of the internal combustion engine when an initial explosion occurs in the first fuel injection will be described. FIG. 2 is a timing chart for explaining the start-up control of the internal combustion engine when the first explosion occurs in the first fuel injection.

  More specifically, FIG. 2 (A) is a diagram showing the operation of the starter motor, and FIG. 2 (B) is a waveform showing a change in time et30 calculated by the ECU 50. FIG. 2 (C) is a diagram showing the state of the initial explosion determination flag, and FIG. 2 (D) is a waveform showing changes in the engine speed of the internal combustion engine. 2E is a waveform showing a change in fuel pressure in the delivery pipe, FIG. 2F is a diagram showing a state of a boost start permission flag, and FIG. 2G is a start completion determination. It is a figure which shows the state of a flag, and FIG.2 (H) is a figure which shows the injection quantity at the time of starting. FIG. 2 (I) is a diagram showing the injection timing, and FIG. 2 (J) is a diagram showing the ignition timing.

  When the starter motor 43 is turned on at time t0 (FIG. 2A), the crankshaft rotates. As a result, the engine speed NE slightly increases as shown in FIG. Further, the ECU 50 calculates a time et30 required for the crankshaft to rotate by 30 ° (FIG. 2B). The rotation of the crankshaft is transmitted to the cam 25 through the camshaft 24. As the cam 25 rotates, the plunger 22 of the high-pressure pump 20 reciprocates up and down. As a result, the fuel pressure from the high pressure pump 20 to the delivery pipe 11 is started. As a result, as shown in FIG. 2 (E), the fuel pressure in the delivery pipe 11 increases.

In the present embodiment, the fuel pressure in the delivery pipe 11 is required to be equal to or higher than the predetermined pressure A as a premise for executing fuel injection from the fuel injection valve 10. The predetermined pressure A is 3 MPa, for example. When the fuel pressure in the delivery pipe 11 becomes equal to or higher than the predetermined pressure A at time t1, the starting injection amount is calculated (FIG. 2 (H)). The starting injection amount is a fuel injection amount suitable for starting. The starting injection amount is set according to the cooling water temperature measured by the water temperature sensor 42. Based on the calculated starting injection amount, the first fuel injection is performed at time t2. Thereafter, ignition by the spark plug 15 is performed. In the present embodiment, the first fuel injection timing is set to the position of top dead center TDC (FIG. 2 (I)), and the first ignition timing is set to the position of ATDC 10 ° CA (FIG. 2). 2 (J)).
In the present embodiment, it is determined whether or not the first explosion has occurred based on the change in time et30. When the first explosion occurs, the rotation speed of the crankshaft increases. For this reason, the time et30 ° is shortened. In the example shown in FIG. 2, the time et30 ° is below the predetermined value B at time t3. Therefore, it is determined that the first explosion has been established by the first fuel injection. The predetermined value B is, for example, a time when the period rotation speed NE is 500 rpm.

  After the first explosion is established, it is necessary to change the fuel injection conditions and the ignition conditions in order to smoothly transition from the first explosion to the complete explosion. In the present embodiment, the starting injection amount is reduced (FIG. 2 (H)), and the ignition timing is retarded and set to a position of ATDC15 ° CA (FIG. 2 (J)). Further, the injection timing is advanced and set to the position of BTDC 30 ° CA for the purpose of securing the time from the injection timing to the ignition timing even when the engine speed NE increases (FIG. 2 (I)). Thereby, the misfire in a high rotation area can be suppressed.

  Thereafter, when the engine speed NE becomes equal to or higher than the predetermined value C at time t4 (FIG. 2D), it is determined that the internal combustion engine has been started. That is, the completion of the complete explosion is detected. Therefore, the starting injection amount is reset (FIG. 2 (H)). Instead of the starting injection amount, a fuel injection amount based on the intake air amount or the like is newly set.

  By the way, the first explosion may not occur in the first fuel injection as described above due to the influence of the properties of the fuel and the like. In this case, it is considered that the possibility of the first explosion is low even if the second and subsequent fuel injections are performed under the same conditions as the first. Therefore, in the present embodiment, as shown in FIG. 3, when the first explosion does not occur, the conditions regarding the first explosion are changed. FIG. 3 is a timing chart for explaining the start-up control of the internal combustion engine when the first explosion does not occur in the first fuel injection.

  More specifically, FIG. 3A is a diagram showing the operation of the starter motor, and FIG. 3B is a waveform showing a change in time et30 calculated by the ECU 50. FIG. 3C is a diagram showing a state of the initial explosion determination flag, and FIG. 3D is a waveform showing a change in the engine speed of the internal combustion engine. FIG. 3 (E) is a diagram showing the number of times of fuel injection, FIG. 3 (F) is a waveform showing a change in fuel pressure in the delivery pipe, and FIG. 3 (G) is a boost start permission flag. It is a figure which shows a state. FIG. 3 (H) is a diagram showing the state of the start completion determination flag, FIG. 3 (I) is a diagram showing the injection amount at start, and FIG. 3 (J) is a diagram showing the injection timing. FIG. 3K is a diagram showing the ignition timing.

  First, as in the example shown in FIG. 2, when the starter motor 43 is turned on at time t0 (FIG. 3A), the crankshaft rotates and the fuel is pumped from the high-pressure pump to the delivery pipe 11. Be started. When the fuel pressure in the delivery pipe 11 becomes equal to or higher than the predetermined pressure A at time t1, the starting injection amount is calculated (FIG. 3 (I)). Based on the calculated starting injection amount, the first fuel injection is performed at time t2. Thereafter, ignition is performed by the spark plug 15. Here, also in the example shown in FIG. 3, the first fuel injection timing is set at the top dead center TDC, and the first ignition timing is set at the ATDC 10 ° CA position.

Unlike the example shown in FIG. 2, the time et30 does not fall below the predetermined value B after the first fuel injection. Accordingly, at time t3, it is determined that the first explosion has not occurred in the first fuel injection, and the initial explosion condition is changed. Specifically, when it is determined that the initial explosion is not established, the starting injection amount is increased (FIG. 3 (I)), the ignition timing advance (FIG. 3 (K)), and the injection timing advance ( FIG. 3J is executed. Under the changed initial explosion condition, the second fuel injection is performed at time t4, and then ignition is performed by the spark plug 15.
Thereafter, the time et30 ° falls below the predetermined value B at time t5. Therefore, it is determined that the first explosion occurred in the second fuel injection.

  After the initial explosion, as in the example shown in FIG. 2, the starting injection amount is reduced (FIG. 3 (I)), and the ignition timing is retarded and set to the ATDC 15 ° CA position (FIG. 3 (K)). ). Further, the injection timing is advanced and set to a position of BTDC 30 ° CA (FIG. 3 (J)).

  In the example shown in FIG. 3, by performing fuel injection and ignition twice after the first explosion is established, the engine speed NE becomes equal to or higher than a predetermined value C at time t7 (FIG. 3 (D)). Thereby, it is determined that the internal combustion engine has been started. Therefore, the starting injection amount is reset (FIG. 3 (I)). Instead of the starting injection amount, a fuel injection amount based on the intake air amount or the like is newly set.

Here, in the prior art already described, the determination of the first explosion is performed based on the engine speed. However, the fluctuation of the engine speed NE is small before and after the initial explosion, that is, from time t4 to time t6 in FIG. 3 (FIG. 3D). For this reason, in the conventional initial explosion determination method based on the engine speed, it is difficult to determine the initial explosion and change the initial explosion conditions by the third fuel injection at time t6.
On the other hand, in the present embodiment, the determination of the first explosion is executed based on the time et30. As clearly shown in FIG. 3, the fluctuation of time et30 is large before and after the first explosion. Therefore, by adopting the initial explosion determination based on the time et30 according to the present embodiment, it is possible to instantaneously determine the initial explosion. Specifically, it is possible to determine the first explosion before the next fuel injection (time t6). Therefore, the next fuel injection and ignition can be executed under the changed initial explosion conditions.

[Specific processing in the embodiment]
FIG. 4 is a flowchart showing the startup control executed by the ECU in the present embodiment.
According to the flow shown in FIG. 4, first, the start completion determination is executed (step 100). Specifically, it is determined whether or not the start completion determination flag exastefi is OFF (step 100). The start completion determination flag exastefi is a flag that is turned on when the engine speed NE is equal to or higher than a predetermined value C as shown in FIGS. 2 (G) and 3 (H). If it is determined in step 100 that the start completion determination flag exastefi is ON, it is determined that start-up control is not necessary, and the process is terminated.

  On the other hand, if it is determined in step 100 that the start completion determination flag exastefi is ON, a boost start permission determination is performed (step 110). Specifically, it is determined whether or not the boost start permission flag exprupinj is ON (step 110). The boost start permission flag exprupinj is a flag that is turned on when the fuel pressure in the delivery pipe 11 becomes equal to or higher than a predetermined pressure A as shown in FIGS. 2 (F) and 3 (G).

  If it is determined in step 110 that the boost start permission flag exprupinj is OFF, it is determined that fuel injection cannot be performed, and thus the process ends. On the other hand, if it is determined in step 110 that the boost start permission flag exprupinj is ON, the initial explosion determination is executed (step 120). Specifically, it is determined whether or not the initial explosion determination flag exengst is OFF (step 120). The initial explosion determination flag exengst is set to ON when the time et30 required for the crankshaft to rotate 30 ° is less than a predetermined value B as shown in FIGS. 2 (C) and 3 (C). Flag. The initial explosion determination flag exengst is processed according to the flow shown in FIG.

  FIG. 5 is a flowchart executed by the ECU 50 for processing the initial explosion determination flag. According to the flow shown in FIG. 5, it is first determined whether or not the starter motor is ON (step 121). If it is determined in step 121 that the starter motor is ON, the initial explosion determination is executed (step 122). More specifically, it is determined whether or not the initial explosion determination flag exengst is OFF.

  If it is determined in step 122 that the initial explosion determination flag “exengst” is ON, the ON operation of the initial explosion determination flag is not necessary, and the process is terminated. On the other hand, if it is determined that the initial explosion determination flag exengst is OFF, it is determined whether or not et30 is smaller than a predetermined value C (step 123).

  If it is determined in step 123 that et30 <C is established, it is determined that the initial explosion has occurred, and therefore the initial explosion determination flag exengst is set to ON (step 124). On the other hand, if it is determined in step 123 that et30 <C is not established, the initial explosion determination flag exengst is set to OFF (step 125).

  If it is determined in step 120 of the flow shown in FIG. 4 that the initial explosion determination flag exengst is OFF, it is determined whether or not the number of fuel injections ecinj is zero (step 130). That is, it is determined whether or not it is the first fuel injection after starting. The number of injections ecinj is set to zero in the initial state immediately after the start of starting, and is counted up in step 170 described later every time fuel injection is performed.

  If it is determined in step 130 that the number of injections ecinj is zero, the initial explosion parameters are calculated (step 140). Here, for the purpose of completing the initial explosion at an early stage, the fuel injection amount, the injection timing, and the ignition timing are calculated according to predetermined rules. Specifically, the ECU 50 includes a map qinj_map1 that defines the relationship between the injection amount suitable for the first explosion and the cooling water temperature, a map ainj_map1 that defines the relationship between the injection timing suitable for the first explosion and the cooling water temperature, and the first explosion. A map aopst_map1 that defines the relationship between the ignition timing suitable for the cooling water temperature and the coolant temperature is stored. In step 140, referring to these maps, the injection amount eqinjcst, the injection timing eainjcst, and the ignition timing eaopst corresponding to the coolant temperature are set. Thereafter, the number of injections ecinj is incremented by 1 (step 170).

When this routine is started after the next time, the determinations of steps 100, 110, and 120 are sequentially performed.
Here, when the first explosion occurs, in step 120, it is always recognized that exegst = OFF is not established. As a result, the parameter after the initial explosion determination is calculated (step 160). Here, for the purpose of smoothly shifting from the first explosion to the complete explosion, the fuel injection amount, the injection timing, and the ignition timing are calculated according to rules different from the rules described in step 140. Specifically, the ECU 50 has a map qinj_map2 that defines the relationship between the injection amount suitable for the first explosion to the complete explosion and the cooling water temperature, and the relationship between the injection timing suitable for the first explosion to the complete explosion and the cooling water temperature. A predetermined map ainj_map2 and a map aopst_map2 that defines the relationship between the ignition timing suitable for the first explosion to the complete explosion and the coolant temperature are stored. In step 160, referring to these maps, the injection amount eqinjcst, the injection timing eainjcst, and the ignition timing eaopst corresponding to the cooling water temperature are set. This step 160 corresponds to the setting of the injection amount, the injection timing, and the ignition timing at time t3 in FIG. 2 and time t5 in FIG.

  In addition, the first explosion may not occur despite the fuel injection. In this case, in step 120, the establishment of exengst = OFF is always permitted. Further, since ecinj count-up processing has already been executed in step 170, it is always recognized that ecinj = 0 is not satisfied in step 140. As a result, the initial explosion parameters are changed by the next fuel injection (step 150). In step 150, the previously set initial explosion parameters are changed so that the first explosion is more likely to occur. Specifically, the previous injection amount multiplied by the correction coefficient K1 is the changed injection amount, and the previous injection timing advanced by the correction coefficient K2 is the changed injection timing. Is obtained by advancing the ignition timing by the correction coefficient K3 as the changed ignition timing. For example, the correction coefficient K1 is 1.05, the correction coefficient K2 is 5 ° CA, and the correction coefficient K3 is 5 ° CA. This step 150 corresponds to the setting of the injection amount, the injection timing, and the ignition timing at time t3 in FIG. Thereafter, the injection count ecinj is incremented by 1 (step 170).

  If the initial explosion still does not take place after the next fuel injection and ignition with the changed initial explosion parameters, the process proceeds to step 150 in the same manner as described above, and the initial explosion parameters are changed again. Is executed.

As described above, in the present embodiment, when the first explosion is not established in the first fuel injection, the parameters for the first explosion are changed, and the first and subsequent parameters are changed after the first explosion. The fuel is injected and ignited. Thereby, the first explosion can be reliably established by the second and subsequent fuel injections. Accordingly, an internal combustion engine start-up control device having good start characteristics can be obtained.
Further, when the first explosion is not established, it is possible to suppress an increase in emission at the time of starting by minimizing the change in the injection amount for the first explosion.

  By the way, in the present embodiment described above, the case where the initial explosion is determined based on the time et30 required for the crankshaft to rotate by an angle of 30 ° has been described. However, the rotation angle is not limited to 30 °, and any angle may be used as long as it is an ignition interval until the next ignition. Also in this case, the first explosion can be determined instantaneously.

  Further, in the present embodiment, the case where fuel is directly injected into the cylinder from the fuel injection valve 10 has been described. However, the present invention is not limited to this. Even in the case of a system that injects fuel from the fuel injection valve into the port, the same effect as in the present embodiment can be obtained.

  In the present embodiment, the case where all parameters of the fuel injection amount, the ignition timing, and the injection timing are changed when the initial explosion is not established has been described, but the present invention is not limited to this. By changing at least one of the above parameters, the same effect as in the present embodiment can be obtained.

  In the present embodiment, the description is limited to the gasoline engine, but the present invention can also be applied to a diesel engine.

  In the present embodiment, when the ECU 50 executes the process of step 150, the “initial explosion parameter changing means” in the first invention executes the process of step 140, and “ "First explosion parameter setting means" has been realized.

It is a figure for demonstrating the system configuration | structure of embodiment of this invention. FIG. 3 is a timing chart for explaining control at the time of starting the internal combustion engine in the embodiment of the present invention (part 1); In the embodiment of the present invention, it is a timing chart for explaining the control at the start of the internal combustion engine (part 2). 4 is a flowchart showing start-up control executed by an ECU in the embodiment of the present invention. It is a flowchart which ECU50 performs for the process of a first explosion determination flag.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel injection valve 11 Delivery pipe 12 Fuel pressure sensor 15 Spark plug 20 High pressure pump 30 Fuel tank 41 Crank angle sensor 42 Water temperature sensor 43 Starter motor 50 ECU (Electronic Control Unit)

Claims (3)

A fuel injection valve for injecting fuel to the internal combustion engine;
Initial explosion determination means for determining whether or not an initial explosion has occurred in the internal combustion engine;
First explosion parameter setting means for setting parameters for the first explosion,
An internal combustion engine start-up control device comprising: an initial explosion parameter changing means for changing the parameter when an initial explosion does not occur with the parameter. The internal combustion engine start-up control device according to claim 1,
The start-up control device for an internal combustion engine, wherein the parameter includes at least one of a fuel injection amount, a fuel injection timing, and an ignition timing. In the internal combustion engine start-up control device according to claim 1 or 2,
The internal combustion engine start-up control device characterized in that the initial explosion determination means determines an initial explosion based on a change in time required for the crankshaft to rotate by a predetermined angle.

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