JP2006214272A - Starting time control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve early activation of a catalyst by elevating the exhaust temperature immediately after starting while holding down the deterioration of a vibration level and NOx to the minimum. <P>SOLUTION: Switching to multi-cycle operation (12 cycle operation) during a first period in which an air pump for supplying the secondary air cannot be operated during cranking, during a second period (Tbth) in which the air pump cannot be operated until the battery voltage is stabilized after the end of cranking, and during a third period of time elapsed from the start of operating the air pump till the delivery amount is stabilized. During 12 cycle operation, fuel is cut in the expansion strokes other than the expansion stroke for normal combustion, or non-combustion is attained by ignition cutting, and in the exhaust stroke immediately after that, the air or unburnt fuel-air mixture is discharged to be substituted for the secondary air. After that, switching to 4-cycle operation is performed so that the exhaust temperature is elevated by the secondary air from the air pump. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a start-up control device for an internal combustion engine that activates an exhaust purification catalyst by operating an air pump immediately after starting to supply secondary air to an exhaust passage to raise exhaust temperature.

  In the technique described in Patent Document 1, secondary air is supplied to the exhaust passage by operating the air pump immediately after starting. In addition, by cutting the fuel for some cylinders, the work of the operating cylinder is increased, the exhaust heat quantity is increased, and the exhaust valve of the idle cylinder is closed to prevent the discharge of low temperature air. Recombustion is promoted by supplying secondary air in the exhaust passage.

In addition, in the technique described in Patent Document 2, in order to eliminate the need for a dedicated air pump for supplying secondary air, fuel is cut for some cylinders, so that exhaust (air) from the cylinders is discharged into the secondary air. Is supplied upstream of the catalyst.
JP 2004-124823 A JP-A-11-3111119

  However, as in Patent Document 1, when using an air pump, priority is given to the operation of the starter motor during cranking. Therefore, the air pump cannot be operated to prevent battery voltage fluctuations immediately after the cranking ends. The secondary air cannot be supplied. Further, it is difficult to supply sufficient secondary air until the discharge amount is stabilized even after the operation of the air pump is started. Accordingly, the supply of secondary air is aimed at early activation of the catalyst immediately after start-up and HC reduction, but secondary air cannot be supplied during the critical period, and a reburning effect cannot be obtained.

  In addition, as in Patent Document 2, a technique in which fuel is cut for some cylinders and the exhaust (air) of the cylinders is used as secondary air is surely effective in improving exhaust temperature immediately after starting and reducing HC. However, during partial cylinder operation, the vibration level of the engine increases and the combustion pressure of the operating cylinder increases, resulting in a large NOx emission. Deterioration becomes remarkable. This also applies to Patent Document 1 in which partial cylinder operation is performed during the supply of secondary air.

  In view of such a situation, the present invention controls the internal combustion engine at the time of start-up that can increase the exhaust temperature immediately after the start and minimize the deterioration of the vibration level and NOx, thereby enabling early activation of the catalyst. An object is to provide an apparatus.

  For this reason, in the present invention, during the period until the secondary air can be supplied to the exhaust passage by the air pump, the normal four-cycle operation is switched to the multi-cycle operation having a larger number of cycles, and during the multi-cycle operation, It is set as the structure which makes it non-combustion in expansion strokes other than the expansion stroke which performs normal combustion, and discharges air or an unburned air-fuel mixture to an exhaust passage in the exhaust stroke immediately after the non-combustion expansion stroke.

  According to the present invention, the multi-cycle operation is performed for a limited period until the supply of the secondary air to the exhaust passage by the air pump becomes possible, and the air or unburned mixture is discharged, and the secondary air is discharged. By substituting for this, it is possible to increase the exhaust temperature immediately after startup and to activate the catalyst early. After this period, the secondary air from the air pump is used, so that the time for multi-cycle operation can be shortened, and the deterioration of the vibration level and NOx can be minimized. Further, even when this is realized by fuel cut, the multi-cycle operation is such that the fuel is cut in a predetermined order in each cylinder, so that the vibration level is less deteriorated than the fuel cut of some cylinders.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an engine system diagram showing an embodiment of the present invention.
In the intake passage 2 of the engine 1, an electrically controlled throttle valve 4 that is positioned on the inlet side of the intake manifold 3 and controls the amount of intake air is installed. The opening degree of the electric throttle valve 4 is controlled by a step motor or the like that is operated by a signal from an engine control unit (hereinafter referred to as ECU) 20.

  A fuel injection valve 6 for injecting fuel to the intake port 5 of each cylinder (directed toward the umbrella portion of the intake valve 7) is attached to the branch portion on the outlet side of the intake manifold 3. The fuel injection valve 6 is opened by energizing the solenoid for a time determined by the pulse width based on the injection pulse signal output from the ECU 20 in synchronization with the engine rotation, and injects the fuel adjusted to a predetermined pressure. .

The air controlled by the electric throttle valve 4 and the fuel injected from the fuel injection valve 6 are sucked into the combustion chamber 10 of the engine 1 when the intake valve 7 is opened.
The air and fuel sucked into the combustion chamber 10 form an air-fuel mixture, which is ignited and burned by the spark plug 11 at the ignition timing controlled by the ECU 20. Exhaust gas after combustion is discharged to the exhaust passage 13 via the exhaust valve 12. An exhaust purification catalyst 14 is provided in the exhaust passage 13.

  Here, secondary air can be supplied upstream of the exhaust purification catalyst 14 in the exhaust passage 13, particularly to the exhaust port 15 of each cylinder in the cylinder head, which is a high temperature part of the exhaust (directed toward the umbrella portion of the exhaust valve 12). In addition, a secondary air supply passage 16 is provided in the cylinder head. An electric air pump 17 for supplying secondary air is provided, and its discharge side is connected to a secondary air supply passage 16 to each cylinder via a shutoff valve 18 and a pipe (gallery) 19. . Note that B in FIG. 1 indicates a battery that is a power source of the air pump 17.

  The ECU 20 includes an accelerator opening APO detected by an accelerator pedal sensor 21, an engine speed Ne detected by a crank angle sensor 22, an intake air amount Qa detected by an air flow meter 23, and an engine detected by a water temperature sensor 24. The coolant temperature Tw, the exhaust air-fuel ratio detected by the air-fuel ratio sensor 25, the catalyst temperature Tc detected by the catalyst temperature sensor 26, and the like are input. Further, a pressure sensor 27 for detecting the pressure (secondary air pressure) 2Ap on the discharge side of the air pump 17 is provided, and a signal is also input from this point. In addition, although not shown, a signal is also input from an engine key switch having an ignition switch and a start switch.

  The ECU 20 controls the opening degree of the electric throttle valve 4, the fuel injection timing and fuel injection amount of the fuel injection valve 6, the ignition timing of the spark plug 11, etc. based on the engine operating conditions detected from these input signals. . Further, the operation of the air pump 17 and the shutoff valve 18 is controlled. The shutoff valve 18 is opened when the air pump 17 is turned on and closed when the air pump 17 is turned off, and can be omitted when the air pump 17 itself has a shutoff function when turned off.

Next, control for early activation (warm-up) of the exhaust purification catalyst 14 immediately after startup will be described with reference to the time chart of FIG.
During cranking at start-up, the air pump is turned off to prioritize the drive of the starter motor.
After the cranking is completed, the air pump is turned off in order to prevent voltage fluctuation until the battery voltage is stabilized. Accordingly, the timer Tb is started from the end of cranking, and the air pump is turned on when the value of the timer Tb reaches a predetermined time Tbth. However, even if the air pump is turned on, there is a delay until the pump discharge amount is stabilized (the secondary air pressure reaches a specified pressure) due to the operation delay.

Thereafter, when the catalyst warm-up is completed, the air pump is turned off again.
On the other hand, normally (in the case of normal temperature starting), the air pump cannot be turned on until the battery voltage is stabilized after the cranking is completed during the first period during which cranking is not possible to turn on the air pump. During the second period (Tbth) and the third period from when the air pump is turned on until the discharge amount is stabilized (secondary air pressure reaches the specified pressure), from the normal four-cycle operation, 4 × Nint ( Nint is an integer greater than or equal to 2, and in the case of a multi-cycle operation with a cycle number such that the combustion between cylinders is equally spaced, a 4-cycle engine is switched to a 12-cycle operation. During the 12-cycle operation, non-combustion is performed in an expansion stroke other than the expansion stroke in which normal combustion is performed, and in the exhaust stroke immediately after the non-combustion expansion stroke, air or unburned mixture (raw gas) Is discharged to the exhaust passage, and this is substituted for the secondary air. Note that air can be discharged when non-combustion is caused by fuel cut, and unburned air-fuel mixture can be discharged when non-combustion is caused by ignition cut.

For this reason, the 12-cycle operation is performed from the start of cranking (in the case of normal temperature start), the secondary air pressure detected by the pressure sensor is monitored from the time when the air pump is turned on, and the secondary air pressure reaches the specified pressure. Thus, the 12-cycle operation is finished and the operation is switched to the 4-cycle operation.
In the case of low-temperature starting (particularly in the case of starting in a cold region), in order to prioritize the starting performance, four-cycle operation is performed from cranking to complete explosion, and 12-cycle operation is started after complete explosion.

  Here, the second period until the battery voltage is stabilized after the cranking is managed by the time Tbth here, but may be managed by providing a sensor for detecting the battery voltage. In addition, the third period until the discharge amount is stabilized after the air pump is turned on is managed by providing a pressure sensor on the discharge side of the air pump, but the timer Tp is started from the time when the air pump is turned on. You may manage by.

Next, regarding the control for early activation (warming up) of the exhaust purification catalyst 14 immediately after starting, the flow chart of the ON / OFF control of the air pump of FIG. 3 and the switching control of the 4-cycle operation / 12-cycle operation of FIG. The flowchart will be described. These flows are executed in time synchronization or rotation synchronization with the start of cranking.
First, the flowchart of ON / OFF control of the air pump of FIG. 3 will be described.

In S1, it is determined whether there is a catalyst temperature increase request. Specifically, the catalyst temperature sensor 26 detects the catalyst temperature Tc and determines whether it is lower than a predetermined activation temperature. The activity / inactivity may be determined by predicting the catalyst temperature from the operating conditions. If there is a catalyst temperature increase request, that is, if the catalyst 14 is inactive, the process proceeds to S2.
In S2, it is determined whether cranking is in progress, that is, whether the start switch is ON. If cranking is in progress, the process proceeds to S3.

In S3, the air pump 17 for supplying secondary air is held in the OFF state, the shutoff valve 18 is also held in the closed state, and the process returns. This is because cranking by the starter motor is being performed, so that consumption of the battery B serving as the power source of the starter motor is suppressed.
If it is determined in S2 that cranking is not being performed (that is, after cranking), the process proceeds to S4.

  In S4, the value of the timer Tb that measures the elapsed time after the end of cranking is compared with a predetermined time Tbth until the battery voltage becomes stable, and it is determined whether or not the timer Tb <Tbth. In this case, that is, until the battery voltage is stabilized, the process proceeds to S3 as described above, the secondary air supply air pump 17 is held in the OFF state, the shutoff valve 18 is also held in the closed state, and the return To do.

If it is determined in S4 that the timer Tb ≧ Tbth, that is, after the battery voltage is stabilized, the process proceeds to S5.
In S5, the air pump 17 for supplying secondary air is turned on, the shutoff valve 18 is opened, and the process returns. However, even if the air pump 17 is turned ON, there is a delay of a predetermined period until the discharge amount of the air pump 17 is stabilized (the secondary air pressure reaches a specified pressure).

If it is determined in S1 that the catalyst temperature increase request is lost, that is, the catalyst warm-up is completed, the process proceeds to S6, the secondary air supply air pump 17 is turned off, and the shutoff valve 18 is closed. To return.
Next, the flowchart of the switching control between the 4-cycle operation and the 12-cycle operation in FIG. 4 will be described.

In S10, as in S1, it is determined whether or not there is a catalyst temperature increase request. If there is a catalyst temperature increase request, that is, if the catalyst 14 is inactive, the process proceeds to S11.
In S11, it is determined whether or not complete explosion determination has been completed. The complete explosion determination is made based on the engine speed Ne or the like. If the complete explosion determination has not been completed, the process proceeds to S12.
In S12, it is determined whether or not it is a condition for prohibiting start in 12-cycle operation (12-cycle start prohibition), specifically, whether or not the engine is cold-started in a cold region where the engine coolant temperature Tw is a predetermined value or less. . If the 12 cycle start is prohibited (low temperature start), the process proceeds to S13.

In S13, the routine returns as a normal four-cycle operation.
If it is determined in S12 that 12-cycle starting is not prohibited (low temperature starting), that is, if starting at room temperature, the process proceeds to S15.
In S15, the operation is switched to the 12-cycle operation and the process returns.
If it is determined in S11 that the complete explosion determination is not completed, that is, after the complete explosion determination, the process proceeds to S14.

In S14, the secondary air pressure 2Ap detected by the pressure sensor 27 is read and compared with a predetermined value 2Apth to determine whether or not 2Ap <2Apth. If 2Ap <2Apth, that is, the discharge amount of the air pump 17 is stable. In the same manner as described above, the process proceeds to S15 until the secondary air pressure reaches the specified pressure (step S15), and the 12-cycle operation is performed.
If it is determined in S14 that 2Ap ≧ 2Apth, that is, after the discharge amount of the air pump 17 is stabilized, the process proceeds to S16.

In S16, it returns to normal four-cycle operation and returns. However, the air-fuel ratio is rich so that the unburned components can be discharged in order to raise the exhaust temperature by burning the unburned components with the secondary air from the air pump 17 in the exhaust passage.
If it is determined in S10 that there is no catalyst temperature increase request, that is, if the catalyst warm-up is completed, the process proceeds to S17.

In S17, since it is a normal operation, it returns as a 4-cycle operation.
Next, in the case of a four-cylinder engine, a mode in which air or unburned mixture is supplied to the exhaust passage instead of secondary air by switching from normal four-cycle operation to twelve-cycle operation will be described in detail. To do.
[First embodiment]
FIG. 5 shows a first mode (mode in which air is discharged by fuel cut).

The 4-cycle operation is four cycles of intake (air mixture) → compression (ignition) → expansion (combustion) → exhaust (burned gas), and the ignition order is # 1 → # 3 → # 4 → # 2. .
In the 12-cycle operation, the pattern of intake → compression → expansion → exhaust is repeated three times, and in one pattern of intake → compression → expansion → exhaust, it is injected into the intake passage in the previous exhaust stroke in the intake stroke. Then, the fuel / air mixture is sucked, and the mixture is ignited in the later stage of the compression stroke, burned in the expansion stroke, and burned gas is discharged in the exhaust stroke. In the remaining two patterns, the previous exhaust stroke injection is not performed (fuel cut), only air is sucked in the intake stroke, non-combustion is performed in the expansion stroke after the compression stroke, and air is discharged in the exhaust stroke.

Therefore, the 12-cycle operation is performed by intake (mixture) → compression (ignition) → expansion (combustion) → exhaust (burned gas) → intake (air) → compression → expansion (non-combustion) → exhaust (air) → intake ( Air) → compression → expansion (non-combustion) → exhaust (air).
It should be noted that the ignition in the compression stroke after inhaling only air in the intake stroke may or may not be cut.

The order of ignition and combustion is as follows: # 1 (combustion) → # 3 → # 4 → # 2 (combustion) → # 1 → # 3 → # 4 (combustion) → # 2 → # 1 → # 3 (combustion) → # From 4 to # 2, combustion between cylinders can be made at equal intervals.
In this case, the air-fuel ratio of the combustion cylinder is set to be rich (the fuel injection amount is increased). This is because unburned fuel in the burned gas discharged from the combustion cylinder is burned with air discharged from the non-burning cylinder.

In addition, since the torque decreases in the multi-cycle operation, it is assumed that the air amount is increased by increasing the throttle opening.
[Second embodiment]
FIG. 6 shows a second mode (a mode in which the unburned mixture is discharged by ignition cut). Different points will be described.

  In the 12-cycle operation, the pattern of intake → compression → expansion → exhaust is repeated three times, and in one pattern of intake → compression → expansion → exhaust, it is injected into the intake passage in the previous exhaust stroke in the intake stroke. Then, the fuel / air mixture is sucked, and the mixture is ignited in the later stage of the compression stroke, burned in the expansion stroke, and burned gas is discharged in the exhaust stroke. In the remaining two patterns, the previous exhaust stroke injection is performed, the air-fuel mixture is sucked in the intake stroke, the ignition is cut off in the compression stroke, non-combustion is performed in the expansion stroke, and unburned mixing is performed in the exhaust stroke. Exhale.

Accordingly, the 12-cycle operation is performed by intake (mixture) → compression (ignition) → expansion (combustion) → exhaust (burned gas) → intake (mixture) → compression (non-ignition) → expansion (non-combustion) → exhaust ( Mixture) → Intake (mixture) → Compression (non-ignition) → Expansion (non-combustion) → Exhaust (mixture)
In this case, the air-fuel ratio of the combustion cylinder is set to stoichiometric to rich, and the air-fuel ratio of the non-combustion cylinder is set to stoichiometric to lean. This is because the air-fuel mixture is discharged from the non-combustion cylinder, and the air-fuel mixture is combusted by the heat of the burned gas discharged from the combustion cylinder (the unburned gas in the burned gas is also burned together).

[Third embodiment]
FIG. 7 shows a third mode (a mode in which discharge of unburned mixture by ignition cut and discharge of air by fuel cut are used in combination). Different points will be described.
In the 12-cycle operation, the pattern of intake → compression → expansion → exhaust is repeated three times, and in one pattern of intake → compression → expansion → exhaust, it is injected into the intake passage in the previous exhaust stroke in the intake stroke. Then, the fuel / air mixture is sucked, and the mixture is ignited in the later stage of the compression stroke, burned in the expansion stroke, and burned gas is discharged in the exhaust stroke. Of the remaining two patterns, in the first pattern, the exhaust stroke injection is performed immediately before, the air-fuel mixture is sucked in the intake stroke, and the ignition is cut in the compression stroke, so that the combustion is not combusted in the expansion stroke. To discharge the unburned mixture. In the other pattern, the immediately preceding exhaust stroke injection is not performed (fuel cut), only air is sucked in the intake stroke, non-combustion is performed in the expansion stroke after the compression stroke, and air is discharged in the exhaust stroke.

Accordingly, the 12-cycle operation is performed by intake (mixture) → compression (ignition) → expansion (combustion) → exhaust (burned gas) → intake (mixture) → compression (non-ignition) → expansion (non-combustion) → exhaust ( Mixture) → Intake (air) → Compression → Expansion (non-combustion) → Exhaust (air)
In this case, the air-fuel ratio of the combustion cylinder is set to stoichiometric to rich, and the air-fuel ratio of the non-combustion cylinder is set to stoichiometric to lean.

The pattern order is the order of combustion pattern → non-combustion pattern by ignition cut → non-combustion pattern by fuel cut. By setting the non-combustion pattern by the fuel cut immediately before the combustion pattern, the non-combustion air-fuel mixture remaining in the cylinder can be driven out.
As described above, according to the present embodiment, when the air pump 17 is operated immediately after startup to supply secondary air to the exhaust passage 13 (exhaust port 15) and the exhaust temperature is raised, the exhaust by the air pump 17 is performed. Multi-cycle operation is performed for a limited period of time until the supply of secondary air to the passage 13 becomes possible, and air or unburned mixture is discharged, and this is used as a substitute for secondary air. Immediately after that, the exhaust temperature can be raised, and the catalyst 14 can be activated early. Then, after this period, by using the secondary air from the air pump 17, the multi-cycle operation time can be shortened, and the deterioration of the vibration level and NOx can be minimized.

Further, even when this is realized by fuel cut, the multi-cycle operation is such that the fuel is cut in a predetermined order in each cylinder, so that the vibration level is less deteriorated than the fuel cut of some cylinders.
Further, by setting the number of cycles in the multi-cycle operation to 4 × Nint (Nint is an integer of 2 or more), a variable valve gear is not required, and the number of cycles is combusted between cylinders according to the number of cylinders. By setting so as to be equally spaced, the stability in the variable cycle can be improved. Specifically, in the case of a 4-cylinder (or 8-cylinder) engine, a 12-cycle operation is practical.

In addition, the period includes the first period during which cranking is performed and the air pump 17 cannot be operated, thereby reducing power consumption during cranking (improving startability by the starter motor) and warming up the catalyst. It is possible to achieve both performance.
In addition, the period includes a second period in which the air pump 17 cannot be operated until the battery voltage is stabilized after the cranking is completed, thereby preventing malfunction due to battery voltage fluctuation and catalyst warm-up performance. Can be made compatible.

In addition, since the period includes the third period from the start of the operation of the air pump 17 until the discharge amount is stabilized, the inexpensive air pump 17 with poor responsiveness can be used, and an increase in cost can be prevented.
Moreover, it is also possible to give priority to the startability by performing the 4-cycle operation from the start of cranking to the complete explosion in the period, and performing the multi-cycle operation after the complete explosion.

In addition, a condition for prohibiting start in multi-cycle operation is set in advance, and in the case of the prohibition condition, during the above period, from the start of cranking to complete explosion, operate for 4 cycles and perform multi-cycle operation after complete explosion. Thus, it is possible to give priority to the startability when starting at a low temperature.
In the above description, the example of a 4-cylinder engine is 12-cycle operation. However, the case of an 8-cylinder engine can also be handled by 12-cycle operation.

In the case of an 8-cylinder engine, as with a 4-cylinder engine, for each cylinder, intake → compression → expansion (combustion) → exhaust → intake → compression → expansion (non-combustion) → exhaust → intake → compression → expansion (non-combustion) → exhaust Assuming 12-cycle operation
When the firing order is # 1 → # 8 → # 7 → # 3 → # 6 → # 5 → # 4 → # 2.
# 1 (combustion) → # 8 → # 7 → # 3 (combustion) → # 6 → # 5 → # 4 (combustion) → # 2 → # 1 → # 8 (combustion) → # 7 → # 3 → # 6 (Combustion) → # 5 → # 4 → # 2 (combustion) → # 1 → # 8 → # 7 (combustion) → # 3 → # 6 → # 5 (combustion) → # 4 → # 2 Become.

It can also be applied to a 6-cylinder engine.
In the case of a 6-cylinder engine, for each cylinder, intake → compression → expansion (combustion) → exhaust → intake → compression → expansion (non-combustion) → exhaust → intake → compression → expansion (non-combustion) → exhaust → intake → compression → expansion (Non-combustion) → exhaust → intake → compression → expansion (non-combustion) → exhaust 20 cycle operation,
When the firing order is # 1 → # 5 → # 3 → # 6 → # 2 → # 4
# 1 (combustion) → # 5 → # 3 → # 6 → # 2 → # 4 (combustion) → # 1 → # 5 → # 3 → # 6 → # 2 (combustion) → # 4 → # 1 → # 5 → # 3 → # 6 (combustion) → # 2 → # 4 → # 1 → # 5 → # 3 (combustion) → # 6 → # 2 → # 4 → # 1 → # 5 (combustion) → # 3 → # 6 → # 2 → # 4 and is an equal explosion.

  In the above description, the case where fuel is injected and supplied into the intake passage has been described. However, the present invention can also be applied to a direct injection type in which fuel is directly injected into the combustion chamber.

Engine system diagram showing one embodiment of the present invention Control time chart for early activation of catalyst immediately after start-up Flow chart of air pump ON / OFF control Flow chart for switching control between 4-cycle operation and 12-cycle operation The figure which shows the 1st aspect of 12 cycle operation The figure which shows the 2nd aspect of 12-cycle driving | operation The figure which shows the 3rd aspect of 12 cycle operation

Explanation of symbols

1 engine
2 Intake passage
3 Intake manifold
4 Electric throttle valve
5 Intake port
6 Fuel injection valve
7 Intake valve
10 Combustion chamber
11 Spark plug
12 Exhaust valve
13 Exhaust passage
14 Exhaust gas purification catalyst
15 Exhaust port
16 Secondary air supply passage
17 Electric air pump
18 Shut-off valve
19 Piping (Gallery)
20 ECU
21 Accelerator pedal sensor
22 Crank angle sensor
23 Air Flow Meter
24 Water temperature sensor
25 Air-fuel ratio sensor
26 Catalyst temperature sensor
27 Pressure sensor

Claims (12)

In the internal combustion engine start-up control device that operates the air pump immediately after the start to supply secondary air to the exhaust passage and raises the exhaust temperature.
During the period until the secondary air can be supplied to the exhaust passage by the air pump, the normal four-cycle operation is switched to the multi-cycle operation having a larger number of cycles, and normal combustion is performed during the multi-cycle operation. Non-combustion during an expansion stroke other than the expansion stroke, and air or unburned mixture is discharged into the exhaust passage during an exhaust stroke immediately after the non-combustion expansion stroke apparatus.   The number of cycles of the multi-cycle operation is 4 × Nint (Nint is an integer of 2 or more), and the number of cylinders is determined so that combustion between the cylinders is equally spaced according to the number of cylinders. The start-up control device for an internal combustion engine according to claim 1.   3. The start-up control device for an internal combustion engine according to claim 2, wherein the multi-cycle operation is a 12-cycle operation in the case of a 4-cylinder or 8-cylinder engine.   In the multi-cycle operation, the pattern of intake → compression → expansion → exhaust is repeated a plurality of times. In one pattern of intake → compression → expansion → exhaust, an air-fuel mixture formed by fuel supply is ignited. The combustion is performed in the expansion stroke, and in the remaining pattern, the fuel is cut, the combustion is made non-combustion in the expansion stroke, and the air is discharged in the exhaust stroke immediately after. A start-up control device for an internal combustion engine according to one.   In the multi-cycle operation, the pattern of intake → compression → expansion → exhaust is repeated a plurality of times. In one pattern of intake → compression → expansion → exhaust, an air-fuel mixture formed by fuel supply is ignited. The combustion is performed in the expansion stroke, and in the remaining patterns, the ignition cut is performed so that the combustion is not performed in the expansion stroke, and the unburned air-fuel mixture is discharged in the immediately subsequent exhaust stroke. The start-up control device for an internal combustion engine according to any one of the above.   In the multi-cycle operation, the pattern of intake → compression → expansion → exhaust is repeated a plurality of times. In one pattern of intake → compression → expansion → exhaust, an air-fuel mixture formed by fuel supply is ignited. Combustion is performed in the expansion stroke, and in at least one of the remaining patterns, the ignition is cut so that the combustion is not combusted in the expansion stroke, and the unburned mixture is discharged in the immediately subsequent exhaust stroke. 4. The start-up control device for an internal combustion engine according to any one of claims 1 to 3, wherein the cut causes non-combustion in the expansion stroke and exhausts air in the exhaust stroke immediately after the cut.   7. The control device for starting an internal combustion engine according to claim 6, wherein a non-combustion pattern by fuel cut is set immediately before one pattern of intake → compression → expansion → exhaust for causing combustion.   The internal combustion engine start-up control device according to any one of claims 1 to 7, wherein the period includes a first period in which the air pump cannot be operated during cranking. .   9. The period according to claim 1, wherein the period includes a second period in which the air pump cannot be operated until the battery voltage becomes stable after the end of cranking. Control device for starting the internal combustion engine.   The internal combustion engine start-up control according to any one of claims 1 to 9, wherein the period includes a third period after the start of operation of the air pump until the discharge amount is stabilized. apparatus.   The start of the internal combustion engine according to any one of claims 1 to 10, wherein a four-cycle operation is performed from a cranking start to a complete explosion in the period, and a multi-cycle operation is performed after the complete explosion. Time control device.   A condition for prohibiting start in multi-cycle operation is set in advance, and in the case of the prohibition condition, from the start of cranking to complete explosion in the above period, four-cycle operation is performed, and multi-cycle operation is performed after complete explosion The start-up control device for an internal combustion engine according to any one of claims 1 to 11.

Images