JPH0754681A - Operation stop control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce a deposit amount deposited in an air intake system after driving stop by controlling the operation stop by cutting off fuel supply for each cylinder with a time difference at the time of detecting an internal combustion engine in stop operation. CONSTITUTION:An internal combustion engine 11 is arranged with an electromagnetic fuel injection valve 15 for each cylinder on the downstream of a throttle valve 14 in an air intake passage 12. The fuel injection valve 15 is controlled by a control unit 16 in accordance with each of detection signals from each of sensors 18, 19 detecting a driving state of the internal combustion engine 11. In this case, by the control unit 16, in accordance with an output signal from an ignition key switch 23, at the time of driving stop of the internal combustion engine 11, each of cylinders is controlled to stop driving with a time difference. Consequently, by discharging blow-by gas by way of using an air flow of the cylinder previously stopped driving, depositing of a deposit is restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control when an internal combustion engine is stopped, and more particularly to a technique for reducing a deposit amount accumulated in an intake system after the stop.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine, when an operation is stopped by an ignition key switch, all cylinders are stopped simultaneously. Even if a fuel injection valve is provided for each cylinder to supply fuel, when the main power of the control unit that performs fuel injection control is turned off, the control signals to each fuel injection valve are stopped at the same time, and fuel injection is stopped simultaneously for all cylinders. (For example, October 15, 1980
See page 2 of "Automotive Engineering Complete Book, Vol. 10, Electrical Equipment, Body Equipment, Engine Parts" issued by Sankaido Co., Ltd. In addition, a device for adjusting the intake air flow rate during idling, for example, an auxiliary air control valve (hereinafter referred to as AAC / V) that controls the auxiliary air flow rate that bypasses the throttle valve, is provided to control the idle rotation speed to the target rotation speed. Generally, the AAC / V is fully closed immediately before the key switch is turned off, and is fully opened after the off operation.

The supply of oil to the lubrication part of the cylinder head is continued until the engine is stopped.

[0004]

However, in such a conventional control system when the engine is stopped, the following problems have occurred. Since all cylinders are instantly stopped due to explosion with a large amount of blow-by gas, the deposit components in the blow-by gas that adhere to the intake passage during operation adhere to the intake valve after the stop, and the intake valve deposit accumulation Was a factor of.

In addition, a deposit accumulates in the AAC / V which is fully closed at the time of idling immediately before the stop, and the AAC / V is
Had caused the sticking of. Furthermore, since the oil is being supplied to the cylinder head just before the stop, there is a large amount of oil remaining in the cylinder head immediately before the stop, and the oil that has entered the cylinder is exposed to the high heat immediately after the stop, which promotes the generation of deposits. It had been.

The present invention has been made in view of such conventional problems, and provides an operation stop control apparatus for an internal combustion engine, which solves various deposit problems by improving control at the time of operation stop. The purpose is to

[0007]

Therefore, as shown by the solid line in FIG. 1, an internal combustion engine operation stop control device according to the present invention performs an engine operation stop operation in an internal combustion engine in which fuel is supplied for each cylinder. And a stop control means for detecting a stop operation of the engine and performing a stop operation by interrupting at least the fuel supply for each cylinder with a time lag after the operation stop operation of the engine is detected. Is characterized by.

Here, the stop control means may control the order of the cylinders to be stopped so that the explosion stroke intervals of the remaining operating cylinders are equalized in accordance with the explosion stroke order. Further, the stop control means may include a means for storing the last stopped cylinder, and the first stopped cylinder may be the last stopped cylinder at the last stopped operation.

Further, the stop control means may be configured to control so that the air-fuel ratio is made lean for each cylinder and then the operation is stopped. In that case, the air-fuel ratio of the cylinder to be stopped may be controlled to be lean as the number of remaining operating cylinders decreases. Further, as shown by the dotted line in FIG. 1, it may be configured to include load adjusting means for increasing the load of the remaining operating cylinders so as to adjust the output reduction due to the operation stop for each cylinder. In that case, the load adjusting means may increase the intake air flow rate by means of adjusting the intake air flow rate when the engine is idle.

As indicated by the alternate long and short dash line in FIG. 1, immediately before the operation of the last cylinder is stopped, the intake air flow rate is increased to the maximum by means for adjusting the intake air flow rate when the engine is idle. It may be configured to include an air flow enhancing means for enhancing. Further, as shown by a chain double-dashed line in FIG. 1, it is configured to include an oil supply stop means for stopping the supply of oil to the cylinder head lubrication portion of the engine when the operation stop control by the stop control means is started. May be.

[0011]

[Operation] When operation is stopped with a key switch,
Since the fuel supply is cut off and the operation is stopped with a time lag for each cylinder, only the air is supplied to the cylinder that was previously stopped and it acts as an air pump, so it remains before the operation is stopped. Blow-by gas is discharged together with air,
Since the deposit contained in the blow-by gas is also discharged, it is possible to prevent the deposit from being deposited on each part. In particular, the effect of preventing deposition on the intake valve of the cylinder is large, but the amount of blow-by gas remaining in the intake system immediately after the engine as a whole is also greatly reduced, so that there is also an effect of inhibiting deposition on AAC / V. Further, since the cooling of the cylinder that has been stopped before is promoted by the air, the amount of deposit generated by the oil that enters after the stop is also reduced.

Further, by controlling the order of the cylinders to be stopped so that the explosion stroke intervals of the plurality of operating cylinders that are left are equalized, the torque fluctuation is suppressed and the rotation is stabilized. Further, if the cylinder that is first stopped is the cylinder that was stopped last at the time of the previous stop, the cylinder that was stopped last has no blow-by gas discharge effect at that time, but When the engine is stopped for the first time, the air is idled for the longest period of time, and the maximum blow-by gas discharge effect is obtained, so the deposit accumulation suppression effect by blow-by gas discharge for each cylinder is equalized. it can.

Further, when the air-fuel ratio is made lean for each cylinder and the control is performed so as to stop the operation, the amount of cleaning air can be increased, so that the deposit suppressing effect can be further enhanced. In that case, the stability of the engine decreases as the number of remaining cylinders decreases, so that the leaner the cylinders that are shut down earlier, the greater the leanness, and the smaller the number of cylinders, the smaller the leanness. The deposit control effect can be enhanced while maintaining the above.

Further, if the load adjustment means is provided to increase the load of the remaining operating cylinders so as to adjust the output reduction due to the operation stop for each cylinder, the stability of the engine can be maintained until the stop is completed. Can be maintained. If the load adjustment is performed by increasing the intake air flow rate by means of adjusting the intake air flow rate when the engine is idle, it can be executed by simple control without providing any special means.

Also, immediately before the operation of the last cylinder is stopped by providing the air flow enhancing means, if the intake air flow rate is increased to the maximum by the means for adjusting the intake air flow rate when the engine is idle, Finally, the deposit components remaining in the intake system can be cleaned with a strong air flow. In particular, when the means for adjusting the intake air flow rate is AAC / V, the effect of preventing deposit accumulation on the AAC / V itself is large by keeping the AAC / V fully open immediately before the stop.

Further, if the oil supply stopping means is provided, the supply of oil to the cylinder head lubricating portion of the engine is stopped before the engine is stopped, so that the amount of oil remaining in the cylinder head portion after the stop is reduced. The amount of deposits generated can be reduced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that this embodiment includes all of the contents of the inventions of claims 1 to 9. 2, the intake passage 12 of the engine 11 is provided with an air flow meter 13 for detecting the intake air flow rate Q and a throttle valve 14 for controlling the intake air flow rate Q in conjunction with an accelerator pedal. An electromagnetic fuel injection valve 15 as fuel supply means is provided for each cylinder in the downstream manifold portion.

The fuel injection valve 15 is opened and driven by an injection pulse signal from a control unit 16 having a built-in microcomputer, and is fuel-fed from a fuel pump (not shown) to be injected and supplied with pressure controlled to a predetermined pressure by a pressure regulator. . Further, an air-fuel ratio sensor 18 for detecting the air-fuel ratio of the intake air-fuel mixture by detecting the oxygen concentration in the exhaust gas in the exhaust passage 17 is provided.

Further, a crank angle sensor 19 is built in the distributor (not shown), and the crank unit angle signal output from the crank angle sensor 19 in synchronization with the engine rotation is counted for a certain period of time, or The engine speed N is detected by measuring the cycle of the reference angle signal.
The auxiliary air passage 20 that bypasses the throttle valve 14 is provided with an AAC / V21 that controls the idle rotation speed by controlling the amount of auxiliary air flowing through the passage 20.

Further, an oil cut valve 22 for stopping the oil supply under the conditions described later is provided in the oil supply passage for supplying the oil to the cylinder head portion of the engine 11. The control unit 16 calculates the fuel injection amount T _I based on the various detection signals detected as described above, drives and controls the fuel injection valve 15 based on the set fuel injection amount T _I , and further, AAC when idle
The idle speed is controlled by controlling the opening of / V21.

Further, the control unit 16 inputs a signal from the ignition key switch 23 and performs stop control for stopping the operation of the engine 11 with a time difference for each cylinder when the operation of the engine 11 is stopped. Details of this operation stop control will be described with reference to the flowcharts shown in FIGS. 3 and 4. In step (denoted as S in the figure. The same applies hereinafter) 1, it is determined whether or not the ignition key switch 23 is turned from on to off, that is, whether or not a driving stop operation is performed. Therefore, the ignition key switch 23 and the function of step 1 constitute the operation stop operation detecting means.

Then, if the operation stop operation has not been performed, this routine is ended, but if the operation stop operation has been performed, the routine proceeds to step 2. In step 2, the oil cut valve 22 is closed. As a result, the supply of oil to the cylinder head portion is stopped, and the amount of oil remaining in the cylinder head after the operation is stopped is reduced, so that the amount of deposit generated by the intrusion of oil into each cylinder can be reduced. That is, the oil cut valve 22,
The function of step 2 constitutes refueling stopping means.

In step 3, the last stopped cylinder when the last stop control was performed is read, and the order of the cylinders to be stopped is set according to this and the ignition order. Here, the last stopped cylinder is set to be first stopped this time, and thereafter, the explosion stroke intervals of the remaining operating cylinders are set to be equalized. For example, if the last stopped cylinder is the first cylinder and the ignition sequence is the first cylinder 1 → the third cylinder → the fourth cylinder → the second cylinder, the first cylinder is stopped first, and then the first cylinder is stopped. By deactivating the four cylinders and operating the second cylinder and the third cylinder, the explosion stroke intervals are made equal. This suppresses torque fluctuations. Next, it is possible to stop the operation from either the second cylinder or the third cylinder. However, even if the stop of the operation is repeated, the operation is stopped in each cylinder. Are equalized and the deposit accumulation suppression effect is equalized in each cylinder. For example, the cylinder that has been stopped before that, the cylinder after the fourth cylinder in the above case, the cylinder on the earlier (or later) ignition order side, that is, the second cylinder (or the third cylinder) is stopped,
Finally, set the third cylinder (or the second cylinder) so that it is stopped.

In step 4, the engine speed N immediately before the stop of the operation detected based on the signal from the crank angle sensor 19 is read, and the operation is stopped before stopping each cylinder based on the engine speed N. For leaning the air-fuel ratio, the set value of the lean air-fuel ratio is obtained by searching from a map obtained in advance. Here, the lean air-fuel ratio is set so that the leaner level becomes smaller as the number of operating cylinders remaining at that time decreases. Specifically, the number of operating cylinders at that time is set so that the cylinder is made lean until it is close to the surge limit when the cylinder is made lean.

In step 5, for the cylinder that is first stopped, that is, the cylinder that was stopped last last time, the fuel injection amount of the cylinder is reduced so that the lean air-fuel ratio read in step 4 is obtained. To control. After that, the routine proceeds to step 6, where the fuel supply to the cylinder controlled to the lean air-fuel ratio is stopped and the operation is stopped. At this time, the output of the ignition signal may be stopped, but since the control becomes complicated, the ignition signal may be output.

As a result, the stopped cylinder, for example, the first cylinder, is supplied with only air until the engine is completely stopped and acts as an air pump. The blow-by gas is discharged together with the air, and the air-fuel ratio becomes lean immediately before the stop. By increasing the amount, the amount of cleaning air is increased, and deposit accumulation can be suppressed as much as possible. In this case, of course, it is possible to effectively prevent the deposit accumulation on the intake valve of the operation stopped cylinder, and it is possible to reduce the blow-by gas remaining in the intake passage, so that the deposit accumulation on the AAC / V21 is suppressed.
Further, since the inside of the cylinder is cooled by the air flow, the amount of deposit produced can be reduced together with the reduction of the amount of residual oil in the cylinder head portion.

Next, the routine proceeds to step 7, where the opening of AAC / V21 set according to the water temperature etc. is increased to the target value set according to the number of operating cylinders in advance. Specifically, as shown in FIG. 5, the target value is set in such a manner that the number of operating cylinders is increased stepwise every time the number of operating cylinders decreases, and when the number of operating cylinders becomes one cylinder, it is fully opened. As a result, the intake air flow rate increases and the output generated by the remaining cylinders increases, so that it is possible to compensate for the engine output that decreases due to the stop of the cylinder operation. That is, the function of step 7 corresponds to the load adjusting means.

In step 8, it is judged whether the engine speed N is maintained below a predetermined value N1, and if it is N1 or more, the routine proceeds to step 9, where the opening of AAC / V is slightly decreased, and the step is repeated. Returning to 8, the same operation is repeated until the engine speed N is maintained below N1. If the engine speed N is increased more than necessary, it is not preferable from the viewpoint of fuel consumption as well, so it is limited.

When the engine speed N is less than N1, the routine proceeds to step 10, where the cylinder to be stopped next is read according to the order of the stopped cylinders set in step 4. For example, in the above example, it is the fourth cylinder that is stopped after the operation of the first cylinder is stopped. In step 11, the stopped cylinders read in step 10 are controlled so that the lean air-fuel ratio set in step 4 is achieved, and then the operation is stopped.

As a result, blow-by gas is discharged together with air in all cylinders until the operation of all cylinders is stopped, and the amount of deposits and the amount of deposits on each portion can be reduced. In step 12, it is determined whether or not the operation of all cylinders has been stopped, and if the operation of all cylinders has not been stopped, the process proceeds to step 13 to determine whether or not the AAC / V21 is fully open. If not fully opened, return to step 7 and perform AAC in the same manner as above.
After increasing the opening degree of / V21 to a target value according to the current number of operating cylinders while maintaining the engine speed N below N1, the next cylinder is controlled to the set lean air-fuel ratio and then stopped. To do.

Also, the remaining operating cylinder is the remaining one cylinder, and AA
If the C / V 21 is fully opened according to the target value, the process returns from step 13 to step 10 to control the last cylinder to the set lean air-fuel ratio and then stop the operation. Here, before the last cylinder is stopped, the AAC / V21 is fully opened or the opening degree is increased as much as possible within a range in which the engine speed is maintained below N1, and the air is supplied through the auxiliary air passage 20. By maximizing the intake air flow rate, the effect of adjusting the load as well as increasing the cleaning air as much as possible and finally cleaning the deposit components remaining in the intake system with the air flow can be maximized. Can be increased. Here, the function of fully opening the opening of the AAC / V21 before stopping the operation of the last cylinder has both the function of the load adjusting means and the function of the air flow enhancing means.

When it is determined in step 12 that the operation of all cylinders has been stopped, the process proceeds to step 14, and the last stopped cylinder is stored in the memory. In step 15, the power supply to the spark plug is stopped and the operation stop control ends. Here, the ignition control of each cylinder may be stopped at the same time as the fuel injection is stopped, but the control becomes complicated, and the purpose of reducing the deposit can be achieved only by stopping the fuel injection, so at least the fuel supply should be stopped. Any configuration may be used as long as the operation is stopped.

In the present embodiment, an embodiment including all the contents of the inventions of claims 1 to 9 is shown, but in claims 2 to 9, some or all of them are omitted. As for the above, it is of course possible to achieve the functions and effects already described for the parts other than the omitted contents.

[0034]

As described above, according to the present invention, the blow-by gas is exhausted by the air flow in the cylinder that has been stopped before because the cylinders are stopped with a time difference. By doing so, it is possible to suppress the accumulation of deposits on each part.In addition, the explosion stroke intervals of the remaining operating cylinders are equalized to stabilize the rotation, and the last stopped cylinder is stopped first. Stop the operation to equalize the deposit accumulation suppression effect in each cylinder, make the air-fuel ratio lean and then stop the operation to enhance the deposit suppression effect, and increase the load on the remaining operating cylinders to increase the engine load. Stability of the cylinder, immediately increase the intake air flow rate immediately before stopping the last cylinder, and finally clean the deposit components remaining in the intake system with a strong air flow. At the same time it is also such that the supply of oil to the cylinder head lubrication reduces the production of deposits stopped.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration and functions of the present invention.

FIG. 2 is a diagram showing the overall configuration of an embodiment of the present invention.

FIG. 3 is a flowchart relating to the first stage of the control routine of the above embodiment.

FIG. 4 is a flowchart according to the latter stage.

FIG. 5 is a map of the target value of the AAC / V opening of the above embodiment.

[Explanation of symbols]

 11 Internal combustion engine 15 Fuel injection valve 16 Control unit 19 Crank angle sensor 20 Auxiliary air passage 21 AAC / V 22 Oil cut valve 23 Ignition key switch

Claims (9)

[Claims] 1. In an internal combustion engine in which fuel is supplied to each cylinder, stop operation detection means for detecting an operation stop operation of the engine and at least fuel supply for each cylinder are cut off after the operation stop operation of the engine is detected. An operation stop control device for an internal combustion engine, comprising: a stop control means for performing an operation stop with a time lag. 2. The stop control means controls the order of cylinders to be stopped so that the explosion stroke intervals of the remaining operating cylinders are equalized according to the explosion stroke order. Stop control device for internal combustion engine. 3. The stop control means includes means for storing a cylinder that has been stopped for the last time, and a cylinder that is stopped for the first time is a cylinder that has been stopped for the last time when the operation was stopped last time. Alternatively, the operation stop control device for the internal combustion engine according to claim 2. 4. The operation of the internal combustion engine according to any one of claims 1 to 3, wherein the stop control means controls the air-fuel ratio for each cylinder to be lean and then stop the operation. Stop control device. 5. The internal combustion engine according to claim 4, wherein the stop control means controls the air-fuel ratio of the cylinder to be stopped to a leaner level as the number of remaining operating cylinders decreases. Shutdown control device. 6. The load adjusting means for increasing the load of the remaining operating cylinders so as to adjust the output decrease due to the stop of the operation of each cylinder. The operation stop control device for an internal combustion engine according to any one of claims. 7. The operation stop control of an internal combustion engine according to claim 6, wherein the load adjusting means is performed by increasing the intake air flow rate by means for adjusting the intake air flow rate when the engine is idle. apparatus. 8. Immediately before stopping the operation of the last cylinder,
8. An air flow enhancing means for enhancing the air flow by maximizing the intake air flow rate by a means for adjusting the intake air flow rate when the engine is idle, and comprising the air flow enhancing means. An operation stop control device for an internal combustion engine according to item 3. 9. An oil supply stop means for stopping the supply of oil to the cylinder head lubrication portion of the engine when the operation stop control by the stop control means is started. [Claim 9] The operation stop control device for an internal combustion engine according to claim 8.