JP4736485B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to control of an internal combustion engine provided with a turbocharger that performs supercharging using exhaust energy.

When a turbocharger that performs supercharging using exhaust energy is applied to an automobile internal combustion engine represented by a gasoline internal combustion engine, as is well known, no supercharging state (supercharging pressure is less than atmospheric pressure) There is a problem that, when accelerating from the state (2), a response delay of the boost pressure rise, so-called turbo lag is caused. In response to such a problem, for example, Patent Document 1 discloses a technique for enriching the mixture ratio when accelerating from a non-supercharging state.
JP 2000-97080 A

  However, such enrichment of the mixing ratio can improve the acceleration response, but causes problems such as a reduction in fuel consumption. Therefore, the enrichment of the mixture ratio should be appropriately performed according to the engine operation state, the degree of acceleration demand by the driver, and the like, and further improvement has been desired. The present invention has been made in view of such problems.

The present invention relates to an accelerator opening detecting means for detecting the opening of an accelerator pedal operated by a driver in an internal combustion engine including a turbocharger that performs supercharging using exhaust energy, Based on the means for obtaining the degree of change, the accelerator opening and the degree of change, a first determination point determined by the accelerator opening and the degree of change, and the accelerator opening is greater than the first determination point and the change Determination means for determining whether the accelerator opening and its rate of change are larger than the determination line connecting the second determination point having a small rate, and means for detecting the supercharging pressure by the turbocharger If, it is determined that the fuel increase region, and, when the boost pressure is below the required boost pressure, and the mixing ratio changing means for changing to the rich side target mixture ratio than the stoichiometric mixture ratio, the excessive If pressure on demand supercharging pressure or is characterized by having a means for inhibiting the enrichment of the target mixture ratio by the mixing ratio changing means.

  According to the present invention as described above, the operation state such as the acceleration transition period from the non-supercharged state to the supercharged state can be achieved with a simple configuration using accelerator position detecting means such as a known accelerator position sensor. The acceleration response can be effectively improved by accurately determining the fuel increase region and enriching the mixture ratio.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the configuration of a spark ignition gasoline internal combustion engine equipped with a turbocharger as an embodiment of the internal combustion engine according to the present invention. A plurality (four in this example) of cylinders 2 are arranged in series in the cylinder block 1, and pistons are slidably fitted in the cylinders 2. A throttle valve 4 for adjusting the intake air amount is arranged in the intake passage 3 for supplying air to the cylinder 2, and a turbocharger 9, specifically, a compressor 9a is interposed on the upstream side thereof. . An exhaust turbine 9 b that drives the compressor 9 a is interposed in the exhaust passage 5. In addition, a boost pressure sensor 12 that detects the boost pressure is disposed downstream of the throttle valve 4 in the intake passage 3.

  As a means for adjusting the supercharging pressure, for example, in this embodiment, the outlet side and the inlet side of the exhaust turbine 9b are connected by an exhaust bypass passage 10, and an electronically controlled wastegate valve 11 is interposed in this passage 10. Has been. The wastegate valve 11 is opened on the engine high speed side so as to keep the supercharging pressure at a predetermined characteristic.

  The control unit 13 includes an accelerator opening APO by an accelerator opening sensor 18 that detects an opening of an accelerator pedal 17 operated by a driver, an engine speed by a rotation speed sensor 15, an intake air amount by an air flow meter 16, In addition to the supercharging pressure by the supercharging pressure sensor 12, detection signals such as cooling water temperature and hydraulic pressure are input. Then, the control unit 13 outputs an injector signal 19 and an ignition signal 20 to the fuel injection valve and the ignition plug based on various detection signals representing these engine operating states, and the fuel injection timing, the fuel injection amount, and the ignition timing. Control etc.

  FIG. 2 is a flowchart showing the flow of control according to the present embodiment. First, in step (denoted as “S” in the figure) 1, the degree of change of the accelerator opening APO, specifically, the rate of change ΔAPO is calculated, and it is determined whether this rate of change ΔAPO is equal to or greater than a predetermined judgment value ΔAPO1. To do. This change rate ΔAPO can be obtained, for example, from the difference between the current accelerator opening and the accelerator opening before a predetermined period (for example, 10 ms).

  In step 2, it is determined whether or not the fuel increase region Z is within a predetermined range based on the accelerator opening APO and the rate of change ΔAPO. This determination can be made with reference to a fuel increase region determination map set and stored in advance as shown in FIG. 3, for example. As shown in FIG. 3, the fuel increase region Z is conditioned on the condition that the accelerator opening APO is equal to or greater than a predetermined determination value APO1 and the change rate ΔAPO is equal to or greater than a predetermined determination value ΔAPO1. More specifically, the fuel increase region Z connects the first determination point (APO1, ΔAPO2) and the second determination point (APO2, ΔAPO1) having a larger accelerator opening and a smaller change rate than the first determination point. This is a region where the accelerator opening and the rate of change are larger than the determination line L1. In short, the fuel increase region Z corresponds to the driver's acceleration request degree combining the accelerator opening APO and the rate of change ΔAPO, and as will be described later, there is no supercharging state (supercharging pressure is less than atmospheric pressure). Therefore, it is precisely matched to the acceleration transient state in which the state toward the supercharging state, that is, the delay in rising of the supercharging pressure, so-called turbo lag, is particularly problematic.

  If it is determined in step 2 that the fuel increase region Z is in effect, output mixture ratio control in steps 3 to 5, that is, fuel increase control is performed. First, in step 3, a target mixing ratio is calculated based on the engine speed and the intake air amount (torque) (mixing ratio changing means). The target mixture ratio at this time is changed / set to at least the rich side (smaller side) than the theoretical mixture ratio. For example, as shown in FIG. 4, the engine speed and the engine torque (intake) are referred to with reference to a setting map (B) for increasing the output mixture ratio that is different from the normal setting map (A) for the theoretical mixture ratio. The target mixture ratio may be set based on the air amount. Alternatively, based on the degree of acceleration request (accelerator opening APO and its change rate ΔAPO), both maps may be interpolated to obtain the target mixture ratio. In the operation region other than the fuel increase region Z, for example, the air-fuel ratio is set toward the stoichiometric air-fuel ratio using a normal setting map as shown in FIG.

  In Step 4, the target ignition timing most suitable for this target mixture ratio is set in consideration of the target mixture ratio set in Step 3. Specifically, the ignition timing is corrected to the advance side according to the amount of fuel increase due to the change of the target mixture ratio to the rich side. In step 5, the fuel injection amount and the ignition timing are set according to the target mixture ratio and the target ignition timing. The fuel injection valve and the spark plug are controlled so that the fuel injection amount and the ignition timing set in this way are obtained.

  In step 6, it is determined whether the supercharging pressure detected by the supercharging pressure sensor 12 has reached a predetermined required supercharging pressure P1 (see FIG. 6). The required supercharging pressure P1 is set based on the accelerator opening APO or the like as is well known. When it is determined that the supercharging pressure has reached the required supercharging pressure P1, the routine proceeds to step 7, where the output mixture ratio control in the above steps 3 to 5 is stopped, and the normal theoretical mixture ratio control, that is, Switch to fuel / ignition timing control for the theoretical mixing ratio.

  FIG. 6 shows a time chart when this embodiment is applied. As shown in the figure, when it is determined that the fuel increase region Z is based on the accelerator opening APO and its change rate ΔAPO, the output mixture ratio control, that is, the fuel increase control is performed as described above. This fuel increase area Z is an operation area where the engine is shifted from the non-supercharged state to the supercharged state at the time of sudden acceleration such as idling or a low load region, or sudden acceleration such as towing or continuous climbing, that is, the acceleration responsiveness is lowered by the turbo lag. Is in good agreement with the acceleration transient, which is particularly problematic. Therefore, by performing enrichment of the mixture ratio in such a fuel increase region Z, the acceleration response can be improved appropriately. In addition, since the change rate ΔAPO of the accelerator opening can be obtained by using a plurality of accelerator openings APO, the fuel increase region is substantially made using only the accelerator opening APO detected by the accelerator opening sensor 18. Z can be determined, and the sensors and control load can be simplified.

  Further, when the supercharging pressure reaches the required supercharging pressure P1, the control is returned to the normal theoretical mixing ratio. That is, when the boost pressure overshoots by the fuel increase control H1 in steps 3 to 5 as shown by the arrow Y1 in FIG. 5 and becomes a torque request value that can be permitted even in the normal fuel control, the fuel as shown by the arrow Y2 The increase control is terminated and the normal fuel / ignition timing control is restored. For this reason, the fuel increase control is not continued excessively, and the rebound such as the reduction in fuel consumption can be suppressed to the minimum.

  Preferably, the accelerator opening APO that becomes the fuel increase region Z is set according to the engine speed so as to be in a supercharging state in a steady state. Then, by determining the fuel increase region Z based on the accelerator opening APO and the rate of change ΔAPO, the fuel increase region Z is determined to be a region where torque is likely to be insufficient, that is, in a non-supercharging state. Therefore, it is possible to more accurately match the acceleration transient state that shifts from the supercharging state to the supercharging state.

  Further, as shown in FIG. 3, the fuel increase region Z may be further divided into a plurality of regions Z1 to Z3 according to the degree of enrichment of the mixture ratio, that is, the degree of fuel increase request.

  The characteristic technical ideas of the present invention that can be grasped from the above description are listed together with the effects thereof. However, the present invention is not limited to the configuration of the embodiment with reference numerals, and includes various modifications and changes without departing from the spirit of the present invention.

  (1) In an internal combustion engine including a turbocharger 9 that performs supercharging using exhaust energy, an accelerator opening detecting means (accelerator opening sensor) that detects an opening APO of an accelerator pedal 17 operated by a driver. 18), a means for determining the change degree (change rate ΔAPO) of the accelerator opening, and a determination means for determining whether or not the predetermined fuel increase region Z is based on the accelerator opening APO and the change degree ΔAPO. (Step 2) and, when it is determined that the fuel increase region Z, the mixture ratio changing means (step 3) for changing the target mixture ratio to the richer side than the theoretical mixture ratio.

  (2) Preferably, means for detecting the supercharging pressure by the turbocharger 9 (when the supercharging pressure sensor 12 is used and the supercharging pressure is equal to or higher than the required supercharging pressure, the target by the mixing ratio changing means is set. And means for prohibiting the enrichment of the mixing ratio (steps 6 and 7).

  (3) Typically, in the fuel increase region Z, the accelerator opening APO is equal to or greater than the predetermined value APO1, and the change degree ΔAPO is equal to or greater than the predetermined value ΔAPO1.

  (4) More preferably, the ignition timing is corrected to the advance side as the target mixture ratio is enriched by the mixture ratio changing means (step 4).

The block diagram which shows simply the control apparatus of a gasoline internal combustion engine provided with the turbocharger which concerns on one Example of this invention. The flowchart which shows the flow of control of a present Example. The characteristic view which shows an example of the fuel increase area | region setting map which concerns on a present Example. The mixing ratio characteristic figure corresponding to the time of normal time (A) and the time of increase (B). Explanatory drawing which shows the aspect which returns to the normal control state from the increase control state which concerns on a present Example. The time chart which shows the change of various characteristic values when the control which concerns on a present Example is applied.

Explanation of symbols

9 ... Turbocharger 12 ... Supercharging pressure sensor 13 ... Engine control unit 18 ... Accelerator opening sensor

Claims (2)

In an internal combustion engine equipped with a turbocharger that performs supercharging using exhaust energy,
An accelerator opening detecting means for detecting the opening of the accelerator pedal operated by the driver;
Means for determining the degree of change in the accelerator opening;
Based on the accelerator opening and the degree of change, a first determination point determined by the accelerator opening and the degree of change, and a second determination point having a larger accelerator opening and a smaller change rate than the first determination point. A determination means for determining whether the accelerator opening and the rate of change of the fuel are greater than the determination line connecting
Means for detecting a supercharging pressure by the turbocharger;
A mixture ratio changing means for changing the target mixture ratio to a richer side than the theoretical mixture ratio when the fuel increase region is determined and the supercharging pressure is less than the required supercharging pressure ;
Means for prohibiting enrichment of the target mixture ratio by the mixture ratio changing means when the supercharging pressure is equal to or higher than the required supercharging pressure;
A control apparatus for an internal combustion engine, comprising: With the enrichment of the target mixture ratio by the mixing ratio changing means, the control apparatus for an internal combustion engine according to claim 1, characterized in that the ignition timing is corrected to the advance side.

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