JP4725555B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  After the engine is started, it is required to stabilize the engine speed at the target idle speed. For this reason, a technique for performing rotational speed feedback control in which the engine rotational speed is feedback controlled by adjusting the ignition timing is conventionally known.

  Japanese Patent Application Laid-Open No. 2004-108172 discloses that if the engine speed is higher than a predetermined engine speed at start-up and lower than the target idle engine speed and the engine speed increase rate is equal to or greater than a predetermined value, the engine speed is A control apparatus for an internal combustion engine that performs only a differential term of number feedback control is disclosed. Further, this device implements a differential term and a proportional term of the rotational speed feedback control based on the ignition timing if the engine rotational speed is higher than the target idle rotational speed and within a predetermined time after starting.

JP 2004-108172 A JP 2004-108246 A

  After starting the engine, we would like to introduce the rotational speed feedback control based on the ignition timing as soon as possible. Immediately after starting, the engine temperature, intake air temperature, fuel atomization, etc. vary widely, making it inappropriate for feedback control. Therefore, the rotational speed feedback control based on the ignition timing cannot be introduced unless the variation is eliminated to some extent.

  When the rotational speed feedback control based on the ignition timing is suddenly started from a certain point in time, the ignition timing changes discontinuously due to the influence of the proportional term and the differential term. As a result, a torque step occurs or an inflection point occurs in the rising curve of the engine speed, so that an occupant tends to feel uncomfortable with engine sound or engine vibration.

  The present invention has been made to solve the above-described problems. After the engine is started, a torque step occurs at the start of the rotational speed feedback control based on the ignition timing, or an inflection occurs in the engine speed increasing curve. It is an object of the present invention to provide a control device for an internal combustion engine that can reliably suppress the occurrence of dots.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
Feedback control means for executing feedback control of the engine speed based on the ignition timing from the time when a predetermined condition is satisfied after the engine is started;
Limiting means for limiting the feedback correction amount after the start of the feedback control;
It is characterized by providing.

The second invention is the first invention, wherein
The limiting means limits the feedback correction amount so that the ignition timing does not change suddenly at the start of the feedback control.

The third invention is the first or second invention, wherein
The limiting unit increases the limit range of the feedback correction amount with the number of ignitions or the elapsed time from the start of the feedback control.

According to a fourth invention, in any one of the first to third inventions,
The feedback control means performs proportional control and / or differential control,
The limiting means limits a proportional term by the proportional control and / or a differential term by the differential control.

According to a fifth invention, in any one of the first to fourth inventions,
The limiting means reduces the limit range of the feedback correction amount as the deviation between the target engine speed and the actual engine speed at the start of the feedback control increases.

According to a sixth invention, in any one of the first to fourth inventions,
The limiting unit increases the limit range of the feedback correction amount as the deviation between the target engine speed and the actual engine speed at the start of the feedback control increases.

  According to the first aspect of the invention, the feedback correction amount can be limited after starting the engine speed feedback control based on the ignition timing at the time of starting the engine. Thereby, it is possible to prevent the ignition timing from becoming discontinuous at the start of the rotational speed feedback control, and it is possible to avoid a sudden change in the engine torque. Therefore, it is possible to sufficiently suppress the occurrence of an inflection point in the engine speed increase curve. For this reason, the engine sound does not change suddenly at the inflection point or engine vibration does not occur, and it is possible to reliably prevent the passenger from feeling uncomfortable.

  According to the second invention, the feedback correction amount can be limited so that the ignition timing does not change suddenly at the start of the rotational speed feedback control. For this reason, since a sudden change in engine torque due to a sudden change in ignition timing can be avoided, the occurrence of an inflection point in the rising curve of the engine speed can be more reliably suppressed.

  According to the third aspect, the limit range of the feedback correction amount can be increased with the number of ignitions or the elapsed time from the start of the feedback control. As a result, the engine speed can be stabilized at the target idle speed at an early stage while reliably suppressing the occurrence of an inflection point in the rising curve of the engine speed.

  According to the fourth invention, the proportional term or differential term of the rotational speed feedback control can be limited. At the start of the rotational speed feedback control, normally, the proportional term and the differential term are likely to be large. However, by limiting the proportional term and the differential term, it is possible to more reliably prevent the ignition timing from becoming discontinuous.

  According to the fifth aspect of the present invention, the limit range of the feedback correction amount can be reduced as the deviation between the target engine speed and the actual engine speed at the start of the speed feedback control is larger. In general, when the deviation is large, an inflection point is likely to occur in the engine speed increase curve. However, according to the fifth aspect, the larger the deviation is, the more the operation of the rotational speed feedback control can be weakened, so that the occurrence of an inflection point can be reliably suppressed.

  According to the sixth invention, the limit range of the feedback correction amount can be increased as the deviation between the target engine speed and the actual engine speed at the start of the speed feedback control is larger. If the deviation is large, that is, if the engine speed at the start of the speed feedback control is low, there is a possibility of engine stall. However, according to the sixth aspect of the invention, the larger the deviation is, the stronger the operation of the rotational speed feedback control can be made, so that engine stall can be prevented more reliably.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining the configuration of the system according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10 mounted on a vehicle. The number of cylinders and the cylinder arrangement of the internal combustion engine 10 are not particularly limited. A piston 12 is provided in each cylinder of the internal combustion engine 10. An intake passage 16 and an exhaust passage 18 communicate with each cylinder.

  An electronically controlled throttle valve 20 is provided in the intake passage 16. A throttle position sensor 22 that detects the opening of the throttle valve 20 (hereinafter referred to as “throttle opening”) is provided in the vicinity of the throttle valve 20. A catalyst 26 for purifying the exhaust gas is disposed in the exhaust passage 18.

  Each cylinder of the internal combustion engine 10 is further provided with a fuel injector 28 for injecting fuel into the intake port, an ignition plug 30 for igniting an air-fuel mixture in the combustion chamber, an intake valve 32, and an exhaust valve 36. ing. The present invention is not limited to the port injection type engine as shown in the figure, but can be applied to an in-cylinder direct injection type engine or an engine using both port injection and in-cylinder direct injection.

  A crank angle sensor 42 for detecting the rotation angle (crank angle) of the crankshaft 24 is provided in the vicinity of the crankshaft 24 of the internal combustion engine 10. An accelerator position sensor 44 for detecting the accelerator pedal position is provided in the vicinity of the accelerator pedal.

  This system includes an ECU (Electronic Control Unit) 50. The ECU 50 is electrically connected to various sensors such as the throttle position sensor 22, the crank angle sensor 42, and the accelerator position sensor 44 described above, and various actuators such as the throttle valve 20, the fuel injector 28, and the spark plug 30 described above. ing.

[Features of Embodiment 1]
After the internal combustion engine 10 is started, the ECU 50 feedback-controls the engine speed NE by adjusting the ignition timing. This control is hereinafter referred to as “rotational speed feedback control”. If the ignition timing is advanced, the engine torque increases, so the engine speed NE increases. On the contrary, if the ignition timing is retarded, the engine torque decreases, so the engine speed NE decreases. The rotational speed feedback control of the present embodiment is executed by combining proportional control and integral control. That is, when executing the rotational speed feedback control, the ECU 50 calculates the feedback correction amount from the proportional term based on the deviation between the target idle rotational speed and the engine rotational speed NE and the integral term based on the integral value of the deviation, The ignition timing is corrected according to the feedback correction amount.

  After the engine is started, the engine speed NE should be introduced as early as possible in order to quickly set the engine speed NE to the target idle speed. However, immediately after start-up, the engine temperature, intake air temperature, fuel atomization, etc. vary widely, and this is an inappropriate state for feedback control. For this reason, the rotation is started from the time when a predetermined condition that can be estimated that such variation has been eliminated to some extent (for example, when a predetermined time has elapsed from the start or when the cooling water temperature reaches a predetermined temperature). Number feedback control is started.

  When the rotational speed feedback control is started, the feedback correction amount with respect to the ignition timing is suddenly introduced from that point, so that the ignition timing changes discontinuously. As a result, a torque step occurs or an inflection point occurs in the engine speed increase curve, so that the engine sound changes or the engine vibration occurs, and the occupant tends to feel uncomfortable. In order to prevent this, in the present embodiment, after the start of the rotational speed feedback control, the feedback correction amount with respect to the ignition timing is limited.

  Hereinafter, in order to facilitate understanding of the operation and effect of the present invention, first, a case where no limitation is imposed on the feedback correction amount after the start of the rotational speed feedback control is taken as a comparative example, and the feedback correction amount and the engine rotational speed NE in this comparative example are used. Will be described.

(Comparative example)
FIG. 4 is a timing chart showing the proportional term, integral term, feedback correction amount, and engine speed NE of the rotational speed feedback control in the case of the comparative example. FIG. 4 shows that the rotational speed feedback control is started at time t ₁ . Since the proportional term is calculated based on the deviation between the target idle speed and the engine speed NE, as shown in FIG. 4A, it rises at a stroke at time t ₁ and then decreases. On the other hand, the integral term is calculated based on the integral value of the deviation between the target idle speed and the engine speed NE, and therefore gradually increases from time t ₁ as shown in FIG. Converges to a value.

Since the feedback correction amount is calculated based on the sum of the proportional term and the integral term, it rises in a step shape at time t ₁ as shown in FIG. Since ignition timing on the basis of such a feedback correction amount is corrected, the ignition timing changes stepwise at time t _1. That is, the ignition timing is changed discontinuously at time t _1. Therefore, the engine torque is suddenly changed (rapidly) at time t _1, as shown in FIG. 4 (d), in the vicinity of the time t _1, an inflection point occurs in ascending curve of the engine rotational speed NE. At this inflection point, the engine sound changes abruptly or engine vibration occurs, so that the occupant tends to feel uncomfortable.

(This embodiment)
Next, the case of the present embodiment, that is, the case where the feedback correction amount is limited after the start of the rotational speed feedback control will be described. FIG. 2 is a timing chart showing a proportional term, an integral term, a feedback correction amount, and an engine rotational speed NE of the rotational speed feedback control in the case of the present embodiment.

The broken line in FIG. 2A indicates the proportional term upper limit guard value. In the present embodiment, the proportional term is limited so that the proportional term is equal to or less than the proportional term upper limit guard value. Proportional term upper limit guard value, with the number of times of ignition from the start time t ₁ of the rotational speed feedback control (or elapsed time), is set so as to gradually increase. The two-point difference line in FIG. 2A is a proportional term before being limited by the proportional term upper limit guard value. By limiting the proportional term before guard by the proportional term upper limit guard value, the proportional term of the present embodiment is calculated as shown by a thick solid line in FIG.

As a result, the feedback correction amount is limited to a form that gradually rises from time t ₁ as shown in FIG. In the present embodiment, since FIG. 2 (c) on the basis of the feedback correction amount as shown ignition timing is corrected, the ignition timing is never changes discontinuously at time t _1, varies continuously. For this reason, since the engine torque does not change suddenly at time t ₁ , it is possible to sufficiently suppress the occurrence of an inflection point in the rising curve of the engine speed NE as shown in FIG. Therefore, the engine sound does not change suddenly at the inflection point or engine vibration does not occur, and it is possible to reliably prevent the passenger from feeling uncomfortable.

As shown in FIG. 2 (a), proportional term guard value PG is calculated according to the number of ignitions from rotational speed feedback control start time t ₁ (or elapsed time), a feedback correction amount by increasing the inclination The limit range becomes larger, and the smaller the slope, the smaller the limit range. Although the slope of the proportional term guard value PG may be constant, the deviation between the target idle speed and the engine speed NE at the speed feedback control start time t ₁ (hereinafter referred to as “initial speed deviation dNE0”), etc. Depending on, the slope of the proportional term guard value PG may be changed.

  For example, when the slope of the proportional term guard value PG is reduced as the initial rotational deviation dNE0 is increased, the limit range for the feedback correction amount is reduced as the initial rotational deviation dNE0 is increased, so that the operation of the rotational speed feedback control is weakened. be able to. In general, when the initial rotation deviation dNE0 is large, an inflection point is likely to occur. However, in this case, the larger the initial rotational deviation dNE0 is, the weaker the operation of the rotational speed feedback control can be, so that the occurrence of an inflection point can be reliably suppressed.

Conversely, when the slope of the proportional term guard value PG is increased as the initial rotational deviation dNE0 is increased, the limit range for the feedback correction amount is increased as the initial rotational deviation dNE0 is increased. can do. When initial rotational deviation dNE0 is large, i.e. when the engine speed NE at time t ₁ is low, the risk of engine stall can be considered. However, in this case, as the initial rotational deviation dNE0 is larger, the operation of the rotational speed feedback control can be strengthened, so that engine stall can be prevented more reliably.

[Specific Processing in Embodiment 1]
FIG. 3 is a flowchart of a routine executed by the ECU 50 in the present embodiment in order to realize the above function. This routine is executed every operation cycle of the internal combustion engine 10. According to the routine shown in FIG. 3, it is first determined whether or not the rotation speed feedback control based on the ignition timing is being executed (step 100).

  If it is determined in step 100 that the rotational speed feedback control is not being executed, the counter SAPC is reset (step 102). That is, SAPC = 0. This counter SAPC is a counter representing the number of ignitions from the start of the rotational speed feedback control.

  If it is determined in step 100 that the rotational speed feedback control is being executed, it is determined whether or not the counter SAPC = 0 (step 104). Since SAPC = 0 at the start of the rotation speed feedback control, the determination in step 104 is affirmed, and then an initial rotation deviation dNE0 is acquired (step 106). That is, the deviation deltaNE between the target idle speed and the engine speed NE at this time is stored as the initial speed deviation dNE0. Subsequently, the counter SAPC is incremented (step 108). On the other hand, if SAPC = 0 is not satisfied in step 104, step 106 is skipped and the counter SAPC is incremented as it is (step 108).

  Subsequently, the proportional term guard value PG is calculated based on the counter SAPC and the initial rotation deviation dNE0 (step 110). The proportional term guard value PG becomes a positive value when the initial rotation deviation dNE0 is positive, and becomes a negative value when it is negative. As shown in FIG. 2A, the absolute value of the proportional term guard value PG is calculated as a larger value as the counter SAPC increases. The slope of the proportional term guard value PG at that time may be changed according to the initial rotation deviation dNE0 as described above.

  Next, it is determined whether the initial rotational deviation dNE0 is positive or negative (step 112). When the initial rotation deviation dNE0 is negative, the proportional term SAP is also negative. Therefore, in this case, it is determined whether or not the proportional term SAP is below the proportional term guard value PG (step 114). As a result, when the proportional term SAP is lower than the proportional term guard value PG, a guard process for limiting the proportional term SAP is executed (step 116). That is, the proportional term SAP is replaced with the proportional term guard value PG as SAP = PG.

  On the other hand, when the initial rotation deviation dNE0 is positive, the proportional term SAP is also positive. Therefore, in this case, it is determined whether or not the proportional term SAP exceeds the proportional term guard value PG (step 118). As a result, when the proportional term SAP exceeds the proportional term guard value PG, a guard process for limiting the proportional term SAP is executed (step 116). That is, the proportional term SAP is replaced with the proportional term guard value PG as SAP = PG.

  In the above-described first embodiment, the case where the proportional term in the rotational speed feedback control is limited has been described. However, in the present invention, when the differential control is performed as the rotational speed feedback control, the differential term is limited. You may do it.

  Further, in the first embodiment described above, the ECU 50 executes the processing of steps 110 to 118 so that the “restricting means” in the first aspect of the invention increases the proportional term guard value PG as the initial rotational deviation dNE0 increases. The “limiter” in the fifth aspect of the present invention is reduced by reducing the slope of the proportional term guard value PG as the initial rotational deviation dNE0 is increased. Each is realized.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. 3 is a timing chart showing a proportional term, an integral term, a feedback correction amount, and an engine speed of the rotational speed feedback control in Embodiment 1 of the present invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention. 7 is a timing chart showing a proportional term, an integral term, a feedback correction amount, and an engine speed of rotation speed feedback control in the case of a comparative example.

Explanation of symbols

10 internal combustion engine 12 piston 16 intake passage 18 exhaust passage 20 throttle valve 26 catalyst 32 intake valve 36 exhaust valve 50 ECU

Claims (5)

Feedback control means for executing feedback control of the engine speed based on the ignition timing from the time when a predetermined condition is satisfied after the engine is started;
Limiting means for limiting the feedback correction amount within a predetermined limit range after the start of the feedback control;
Equipped with a,
The control device for an internal combustion engine, characterized in that the limit means reduces the limit range of the feedback correction amount as the deviation between the target engine speed and the actual engine speed at the start of the feedback control increases . Feedback control means for executing feedback control of the engine speed based on the ignition timing from the time when a predetermined condition is satisfied after the engine is started;
Limiting means for limiting the feedback correction amount within a predetermined limit range after the start of the feedback control;
With
The control device for an internal combustion engine, wherein the limiting means increases the limit range of the feedback correction amount as the deviation between the target engine speed and the actual engine speed at the start of the feedback control increases. 3. The control apparatus for an internal combustion engine according to claim 1, wherein the limiting means limits the feedback correction amount so that the ignition timing does not change suddenly at the start of the feedback control. It said limiting means, the feedback correction amount of the limit range of any one of claims 1 to 3, characterized in that is increased with the number of times of ignition or time elapsed from the start of the feedback control Control device for internal combustion engine. The feedback control means performs proportional control and / or differential control,
It said limiting means, the control device of the proportional control by the proportional term and / or any one of claims internal combustion engine according to claim 1 to 4 characterized in that said limiting the differential term by differential control.

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