JP5999070B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine having a throttle valve in an intake pipe.

  A control device for an internal combustion engine (hereinafter also simply referred to as “engine”) mounted on a vehicle generally has a throttle valve opening (that is, a throttle opening based on an accelerator opening, an engine speed, and the like). ). Further, the control device predicts the amount of air flowing into the combustion chamber from the throttle opening (hereinafter also simply referred to as “air amount”), and based on the predicted air amount, the fuel injection amount, the injection timing, etc. To decide. Therefore, the control device stores the relationship between the throttle valve opening and the air amount in the form of a map and a calculation formula.

  However, when the engine is operated for a long period of time, deposits adhere to the throttle valve and the inner wall of the intake pipe. When deposits are deposited, the air passage cross-sectional area with respect to the throttle opening decreases, so that the air amount decreases even if the throttle opening is the same.

  Therefore, an apparatus that predicts the air amount using the relationship between the throttle opening degree and the air amount stored in advance cannot accurately estimate the air amount due to deposit adhesion. Therefore, the conventional control device predicts the air amount more accurately by measuring the actual air amount using an air flow meter installed in the intake pipe and learning the relationship between the throttle opening and the air amount. It is supposed to be.

  More specifically, one of the conventional devices (conventional device) learns the flow rate characteristic value of the air passing through the throttle valve for each opening range divided according to the throttle opening. Further, when there is an unlearned opening area, the conventional apparatus sets (copy) the flow characteristic value learned for the opening area where the throttle opening is larger than the opening area as the learning value of the unlearned area (For example, refer to Patent Document 1).

JP 2012-17679 A

  By the way, the conventional device stores a learning value (flow rate characteristic value) in a certain opening region in correspondence with a throttle opening (learning throttle opening) in the opening region. Then, when the actual throttle opening is “an opening between a certain learning throttle opening and a learning throttle opening adjacent to the learning throttle opening”, the conventional device opens the two learning throttles. The air quantity with respect to the actual throttle opening is predicted by, for example, linear interpolation using two learning values corresponding to degrees.

  On the other hand, when the engine is in an idle state, the throttle opening is smaller than when the engine is driving the vehicle. In particular, when the engine is not loaded, such as when the engine is idle and the warm-up operation is completed and the air conditioner is not operating (this state is also referred to as “no-load idle state” hereinafter). The throttle opening is minimized.

  However, as described above, the amount of air with respect to the same throttle opening decreases as deposits adhere. Therefore, the throttle opening (hereinafter also referred to as “no-load idle opening”) for securing the amount of air necessary to maintain the no-load idle state increases as the deposit amount increases. . Therefore, as the deposit amount increases, the no-load idle opening increases, so the frequency of engine operation at a throttle opening smaller than the increased no-load idle opening decreases drastically. As a result, a situation occurs in which the learned value for the opening region smaller than the increased no-load idle opening is not updated.

  On the other hand, the learning value corresponding to the throttle opening larger than the no-load idle opening is continuously updated. As a result, the air amount for an opening whose throttle opening is in the vicinity of the no-load idle opening and slightly larger than the no-load idle opening is set to a learning value that is continuously updated and a learning value that is not updated. Since it is calculated | required based on (for example, by linear interpolation), the problem that it cannot obtain | require accurately arises.

  Accordingly, one of the objects of the present invention is a control device for an internal combustion engine capable of accurately estimating the air amount with respect to the throttle opening in the vicinity of the no-load idle opening even when deposits are attached. Is to provide.

In order to achieve the above object, a control device for an internal combustion engine of the present invention (hereinafter also referred to as “the present invention device”) is provided.
Storing in advance the relationship between the initial air amount, which is the amount of air flowing through the intake pipe when there is no deposit on the intake pipe and the throttle valve of the internal combustion engine, and the throttle opening;
The throttle opening for ensuring the amount of air necessary for the engine to maintain the no-load idle operation state is determined as the no-load idle opening,
The flow rate loss rate, which is the ratio of the actual air amount to the initial air amount, is obtained for the learning throttle opening determined for each predetermined throttle opening region, and the obtained flow loss rate is set to the learned throttle opening. Obtained as the corresponding learning value,
The air amount corresponding to the throttle opening is calculated based on the learned value, and the calculated air amount is used for controlling the engine.

Furthermore, the device of the present invention
A small opening side learning value that is the learning value corresponding to the maximum opening within a range smaller than the determined no-load idle opening among the learning throttle opening,
If the learning throttle opening is larger than the large opening side learning value, which is the learning value corresponding to the minimum opening within a range larger than the no-load idle opening.
The small opening side learning value is set to a value corresponding to the large opening side learning value.

  According to the device of the present invention, even when the no-load idle opening becomes larger than when there is no deposit due to deposit adhesion, that is, when a throttle opening region where the learning value is not updated occurs. Even if it exists, the learning value used in order to calculate inflow air amount can be correct | amended.

  As a result, the apparatus according to the present invention is capable of calculating the inflow air calculated with respect to the throttle opening even when the throttle opening is close to the opening in the no-load idle state or when the throttle opening is slightly larger than that. It becomes possible to suppress the quantity error. Accordingly, the device of the present invention can avoid the occurrence of phenomena such as instability of the rotational speed, lowering of the fuel consumption rate, and deterioration of exhaust emission due to incorrect calculation of the inflowing air.

1 is a schematic configuration diagram of an internal combustion engine to which a control device (first device) according to a first embodiment of the present invention is applied. It is the graph which showed the relationship between the throttle opening degree in 1st apparatus, the inflow air amount, and the flow loss rate (learning value). It is the graph which showed the relationship between the throttle opening degree in 1st apparatus, the inflow air amount, and the flow loss rate (learning value). It is the flowchart which showed the correction control which a 1st apparatus performs. It is the graph which showed the relationship between the throttle opening degree, the inflow air amount, and the flow loss rate (learning value) in the control apparatus (2nd apparatus) which concerns on 2nd Embodiment of this invention. It is the flowchart which showed the correction control which a 2nd apparatus performs.

  Hereinafter, a control device for an internal combustion engine according to each embodiment of the present invention will be described with reference to the drawings.

<First Embodiment>
The control device for an internal combustion engine according to the first embodiment of the present invention (hereinafter also referred to as “first device”) is applied to the internal combustion engine 10 shown in FIG. The engine 10 is mounted on a vehicle (not shown). The engine 10 includes an intake pipe 11, a combustion chamber 21, and an exhaust pipe 31.

  The intake pipe 11 is provided with a throttle valve 12, a throttle valve actuator 13, and a fuel injection valve (injector) 14. The throttle valve actuator 13 changes the opening degree (throttle opening degree) TA of the throttle valve 12 in response to an instruction from an ECU (electronic control unit) 40 described later, and controls the air flow rate in the intake pipe 11. The fuel injection valve 14 injects fuel into the intake pipe 11 in response to an instruction from the ECU 40.

  A spark plug 22 is disposed in the combustion chamber 21. The spark plug 22 ignites the air-fuel mixture in the combustion chamber 21 in accordance with an instruction from the ECU 40.

  An intake valve 23 disposed between the intake pipe 11 and the combustion chamber 21 is opened and closed by an intake camshaft (not shown). The exhaust valve 24 disposed between the combustion chamber 21 and the exhaust pipe 31 is opened and closed by an exhaust camshaft (not shown).

  The ECU 40 includes a CPU 42, a ROM 43, a RAM 44 and a backup RAM 45. The backup RAM 45 can hold the written data even when power is not supplied to the ECU 40. Accordingly, a learning value to be described later is stored in the backup RAM 45. The ECU 40 is connected to sensors described below, and receives (inputs) signals from these sensors.

  The air flow meter 51 measures the mass flow rate (air flow rate) of the incoming air passing through the intake pipe 11 and outputs a signal representing the air flow rate Ga. The throttle opening sensor 52 outputs a signal indicating the throttle opening TA of the throttle valve 12. The accelerator opening sensor 53 outputs a signal indicating the opening Acc of an accelerator pedal (not shown) of the vehicle on which the engine 10 is mounted. The crank angle sensor 54 outputs a signal corresponding to the rotational position of a crankshaft (not shown) of the engine 10. The ECU 40 calculates the engine speed NE of the engine 10 based on the signal from the crank angle sensor 54.

<Calculation of air flow through throttle and learning of flow loss rate>
Next, the operation of the ECU 40 will be described. A curve Li in FIG. 2A indicates that “the amount of air passing through the throttle mt corresponding to the throttle opening degree TA when there is no deposit on the inner wall of the throttle valve 12 and the intake pipe 11 (for example, when the engine 10 is new). (That is, air flow characteristics) ”. The throttle passing air amount mt is a value obtained by the product of the air filling rate KL and the rotational speed NE (that is, mt = KL × NE), and has a positive correlation with the air flow rate Ga. Here, the air filling rate KL is a value representing the amount of air filled in the combustion chamber 21 as a percentage. Specifically, when the volume of air equal to the displacement of the engine 10 passes through the intake pipe 11 during one revolution of the engine 10, the air filling rate KL becomes 100%. The curve Li is stored in the ROM 43 in the form of a map. The throttle passage air amount mt represented by the curve Li is hereinafter also referred to as “initial inflow air amount mti”.

  The throttle opening degree TAmi in FIG. 2 (A) is determined when the engine 10 is in a no-load idle state (that is, the engine 10 is in an idle state and no load is applied from the outside, more specifically, The throttle opening which gives the minimum inflow air amount mtm required for the engine 10 to maintain the warm-up operation and the condition that the auxiliary load such as an air conditioner and electric load (not shown) mounted on the vehicle is not operating) TA (ie, no-load idle opening).

  The ECU 40 determines the throttle opening TA at a predetermined timing using a known method based on the accelerator opening Acc and the rotational speed NE. The ECU 40 acquires the throttle passing air amount mt corresponding to the throttle opening degree TA by referring to the map of the ROM 43. The ECU 40 calculates the amount of air flowing into the combustion chamber 21 (cylinder air amount) based on the throttle passage air amount mt, and determines the fuel injection amount, fuel injection timing, and the like based on the cylinder air amount.

  By the way, during operation of the engine 10, soot contained in the blowback from the combustion chamber 21 and dust contained in the outside air adhere to the throttle valve 12 and the inner wall of the intake pipe 11, and then the throttle valve as deposit (attachment). 12 and the inner wall of the intake pipe 11. As the deposit adheres, the air cross-sectional area decreases, so that the throttle passage air amount mt corresponding to the same throttle opening degree TA is reduced as compared with that before deposit deposition.

  A curve La in FIG. 2A represents the air flow rate characteristic of the throttle valve 12 in a state where deposits are attached (that is, a state where the throttle passage air amount mt corresponding to the same throttle opening degree TA is reduced). As will be understood from the curve Li and the curve La, when deposit adhesion occurs, the ECU 40 refers to map information corresponding to the curve Li stored in the ROM 43 (that is, the initial inflow air amount mti). The throttle passage air amount mt corresponding to the throttle opening degree TA cannot be acquired correctly. Therefore, the ECU 40 learns a value having a correlation with the actual throttle passing air amount mt for each predetermined throttle opening range.

  More specifically, the ECU 40 determines the actual throttle passing air amount mts (s = 1) corresponding to the learned throttle opening TAs (s = 1, 2,...) Included in each of the predetermined throttle opening regions. , And..., And the initial inflow air amount mtis (s = 1, 2,...) Corresponding to the learned throttle opening degree TAs. Next, the ECU 40 calculates the flow rate loss rate LRs (s = 1, 2,...) Corresponding to the learned throttle opening degree TAs by dividing the throttle passage air amount mts by the initial inflow air amount mtis (ie, , LRs = mts / mtis). The ECU 40 stores the flow rate loss rate LRs corresponding to each learned throttle opening degree TAs in the backup RAM 45 as a learned value.

  On the other hand, the ECU 40 calculates the throttle passing air amount mt corresponding to the actual throttle opening degree TA by referring to the learning value stored in the backup RAM 45. Now, it is assumed that the deposit adherence causes the relationship between the throttle opening degree TA and the throttle passing air amount mt to be as shown by a curve La in FIG.

  For example, when the actual throttle opening is equal to the learned throttle opening TA3, the ECU 40 indicates “mti3 which is the initial inflow air amount corresponding to the throttle opening TA3” shown in FIG. “Flow rate loss rate LR3 which is a learning value corresponding to throttle opening degree TA3” shown in (B) is acquired. Next, the ECU 40 calculates the throttle passage air amount mt3 corresponding to the throttle opening degree TA3 by multiplying the initial inflow air amount mti3 by the flow rate loss rate LR3 (that is, mt3 = mti3 × LR3).

  On the other hand, when there is no learning value corresponding to the actual throttle opening TA, that is, when the actual throttle opening TA is different from any learning throttle opening, the ECU 40 calculates the throttle passing air amount mt by linear interpolation. To do. Assume that the actual throttle opening is TAx between the learning throttle opening TA3 and the learning throttle opening TA4 (that is, TA3 <TAx <TA4).

In this case, the ECU 40 acquires a flow rate loss rate LR3 corresponding to the learned throttle opening degree TA3 and a flow rate loss rate LR4 corresponding to the learned throttle opening degree TA4. Next, the ECU 40 calculates a flow rate loss rate LRx corresponding to the throttle opening degree TAx by linear interpolation. That is, the ECU 40 calculates LRx based on the following equation.
LRx = (LR4-LR3) * (TAx-TA3) / (TA4-TA3) + LR3

  Further, the ECU 40 acquires “mtix, which is an initial inflow air amount corresponding to the throttle opening degree TAx” shown in the curve Li in FIG. 2A, and multiplies the initial inflow air amount mtix by the flow rate loss rate LRx. To calculate the throttle passage air amount mtx corresponding to the throttle opening degree TAx (that is, mtx = mtix × LRx).

<Calculation error of air flow through throttle>
Next, it will be described that the throttle passage air amount mt calculated by the ECU 40 based on the learned value under specific conditions can include an error. Point Pi1 to point Pi4 in FIG. 2A are throttle passage air amounts mt (that is, initial inflow air amounts) corresponding to the learned throttle openings TA1 to TA4 when there is no deposit adhesion. In this case, the points Pi1 to Pi4 are located on the curve Li. Points Pir1 to Pir4 on the straight line Lir in FIG. 2B are combinations of the throttle opening degree TA and the flow rate loss rate LR corresponding to the points Pi1 to Pi4 in FIG. In this case, no deposit adhesion has occurred, that is, no decrease in the throttle passage air amount mt has occurred, so that the flow rate loss rate LR is all “1”.

  Next, it is assumed that the deposit adherence causes the relationship between the throttle opening degree TA and the throttle passing air amount mt to be as shown by a curve La in FIG. As a result of deposit adhesion, the no-load idle opening increases from TAmi to TAma (ie, TAmi <TAma). In other words, during operation of the engine 10, the throttle opening degree TA does not become smaller than TAma. Since the learning throttle opening degree TA1 is smaller than TAma (that is, TA1 <TAma), the learning value (flow rate loss rate LR) corresponding to the learning throttle opening degree TA1 is not updated. The region where the throttle opening TA is smaller than the “no-load idle opening” is also referred to as “learning impossible region” in the present specification.

  On the other hand, learning values corresponding to learning throttle openings TA2 to TA4 larger than TAma (that is, TAma <TA2 <TA3 <TA4) are updated by learning. The updated learning values are represented as points Par2 to Par4 in FIG.

  As described above, when the actual throttle opening degree TA is different from any learning throttle opening degree, the ECU 40 calculates the flow rate loss rate LR by linearly interpolating the learning value. That is, the ECU 40 calculates the flow rate loss rate LR based on the thick line Lamr obtained by connecting the points Pir1 and Par2 to Par4 in FIG.

  When the throttle opening degree TA corresponds to the area Sar in FIG. 2B, that is, when the throttle opening degree TA is between the minimum idle opening degree TAma and the learned throttle opening degree TA2, the ECU 40 determines the learning value Pir1 as The flow rate loss rate LR is calculated by linear interpolation based on the learning value Par2. However, since the learning value Pir1 is not updated, the flow rate loss rate LR calculated based on the learning value Pir1 includes an error. Since the ECU 40 calculates the throttle passage air amount mt based on the flow rate loss rate LR including an error, the throttle passage air amount mt also includes an error.

  More specifically, the point Pa2 in FIG. 2 (A) includes an initial inflow air amount mti corresponding to the learning throttle opening TA2, a flow rate loss rate LR (learning value) corresponding to the learning throttle opening TA2, and The throttle passage air amount mt calculated on the basis of Similarly, points Pa3 and Pa4 in FIG. 2A represent throttle passing air amounts mt corresponding to the learned throttle openings TA3 and TA4, respectively. A thick line Lam obtained by connecting the point Pi1 and each of the points Pa2 to Pa4 with a line segment is an actual throttle opening TA, a throttle passing air amount mt calculated by the ECU 40 based on the throttle opening TA, Represents the relationship. As understood from the region Sa in FIG. 2A, when the throttle opening degree TA is between the minimum idle opening degree TAma and the learning throttle opening degree TA2, the throttle passing air amount mt calculated by the ECU 40 has an error. Including.

  The ECU 40 determines the amount of fuel injected from the fuel injection valve 14, the injection timing, and the like based on the throttle passage air amount mt having an error, so that the injection fuel amount also depends on the error of the throttle passage air amount mt. An error occurs, and as a result, the air-fuel ratio in the combustion chamber 21 differs from the target value. As a result, there is a risk that a reduction in the fuel consumption rate and a deterioration in exhaust emission may occur. In some cases, the rotational speed NE becomes unstable (that is, hunting occurs), and further blow-up and engine stall may occur.

<Correction control>
In order to avoid this problem, the ECU 40 according to the present embodiment executes “correction control” described below. As described above, the flow rate loss rate LR is the ratio of the actual throttle passing air amount mt to the initial inflow air amount mti. In general, the smaller the throttle opening degree TA, the smaller the air passage cross-sectional area of the intake pipe 11, so that the influence of deposit adhesion on the throttle passage air amount mt becomes relatively large. In other words, if the deposit adhesion amount is the same, the smaller the throttle opening TA, the smaller the flow rate loss rate LR.

  On the other hand, as the deposit amount increases, the actual throttle passing air amount mt decreases, so the flow rate loss rate LR decreases. However, the learning value (flow rate loss rate LR) that is not updated due to the increase in the no-load idle opening degree (that is, the expansion of the learning impossible region) due to the increase in the deposit adhesion amount does not decrease. In other words, a phenomenon occurs in which the learning value that is not updated on the smaller opening side than the no-load idle opening is larger than the learning value that is updated on the larger opening side than the no-load idle opening. In this case, the ECU 40 determines that the flow rate loss rate LR (and the throttle passing air amount mt) calculated based on the learned value includes an error.

  More specifically, the ECU 40 determines that “the flow rate loss rate LR1 corresponding to the maximum learned throttle opening in the range of the smaller opening than the no-load idle opening (TAma in this example)” and “no-load The flow rate loss rate LRr corresponding to the minimum learning throttle opening in the range of the larger opening than the idle opening is compared. In this example, the flow rate loss rate LR1 on the smaller opening side than the no-load idle opening degree TAma is the flow rate loss rate LR (point Pir1) corresponding to the learning throttle opening degree TA1, and is higher than the no-load idle opening degree TAma. The flow rate loss rate LRr on the large opening side is the flow rate loss rate LR (point Par2) corresponding to the learned throttle opening TA2.

  When the flow rate loss rate LRl on the small opening side is larger than the flow rate loss rate LRr on the large opening side (that is, LRl> LRr), the ECU 40 does not update the learning value corresponding to the flow rate loss rate LRl, that is, calculates It is determined that the error (region Sar and region Sa) has occurred in the flow rate loss rate LR (and the throttle passing air amount mt).

  In this case, the ECU 40 corrects the learning value so that the value of the flow rate loss rate LRl becomes equal to the value of the flow rate loss rate LRr. That is, in this example, the ECU 40 corrects the learning value Pir1 corresponding to the learning throttle opening degree TA1 to be equal to the learning value Par2 corresponding to the learning throttle opening degree TA2. The learning value corresponding to the corrected learning throttle opening degree TA1 is the point Par1.

  A point Pa1 in FIG. 2A represents a throttle passing air amount mt corresponding to the point Par1 in FIG. The point Pa1 is located closer to the curve La than the point Pi1 corresponding to the learning value Pir1 to be corrected. That is, by the correction control, even when the throttle opening degree TA is in the vicinity of the no-load idle opening degree and slightly larger than the no-load idle opening degree, the ECU 40 controls the throttle opening degree TA corresponding to the throttle opening degree TA. The passing air amount mt can be calculated with higher accuracy.

  Next, it is assumed that as a result of further progress of deposit adhesion, the relationship between the throttle opening degree TA and the throttle passing air amount mt is as shown by a curve Lb in FIG. In this case, the no-load idle opening is TAmb (that is, TAma <TAmb).

  Since the learned throttle openings TA1 and TA2 corresponding to the points Par1 and Par2 in FIG. 3B are smaller than the no-load idle opening TAmb (that is, TA1 <TA2 <TAmb), The corresponding learning value is not updated. On the other hand, since the learning throttle openings TA3 and TA4 corresponding to the points Pa3 and Pa4 are larger than the no-load idle opening TAmb (that is, TAmb <TA3 <TA4), the learning values are updated to the points Pbr3 and Pbr4, respectively. Is done. Therefore, if correction control is not performed, the ECU 40 calculates the flow rate loss rate LR based on the thick line Lbmr. As a result, in the range of the throttle opening TA shown in the region Sbr (that is, the range from the no-load idle opening TAmb to the learning throttle opening TA3), the flow rate loss rate LR calculated by the ECU 40 includes an error.

  The thick line Lbm in FIG. 3A corresponds to the thick line Lbmr in FIG. Point Pb3 and point Pb4 in FIG. 3A correspond to point Pbr3 and point Pbr4 in FIG. 3B, respectively. The ECU 40 calculates the throttle passing air amount mt based on the flow rate loss rate LR including an error when the throttle opening degree TA is in the range of the region Sb (that is, the range from the no-load idle opening degree TAmb to the learning throttle opening degree TA3). Therefore, the throttle passage air amount mt also includes an error.

  Therefore, the ECU 40 executes “correction control” in order to suppress an error in the throttle passage air amount mt. In this example, the flow rate loss rate LRl on the small opening side is the flow rate loss rate LR corresponding to the point Par2 (that is, the learning throttle opening TA2), and the flow rate loss rate LRr on the large opening side is the point Pbr3 (ie, the point Pbr3). , The flow rate loss rate LR corresponding to the learning throttle opening degree TA3). In this example, since the flow rate loss rate LRl on the small opening side is larger than the flow rate loss rate LRr on the large opening side, the ECU 40 indicates that the above error (region Sbr) occurs in the calculated flow rate loss rate LR. judge.

  In this case, the ECU 40 corrects the learning value corresponding to the flow rate loss rate LRl so that the value of the flow rate loss rate LRl becomes equal to the value of the flow rate loss rate LRr. Specifically, the ECU 40 sets the point Par1 and the point Par1 so that the flow rate loss rate LR corresponding to the points Par1 and Par2 is equal to the flow rate loss rate LRr on the large opening side (flow rate loss rate LR corresponding to the point Pbr3). The point Par2 is corrected to a point Pbr1 and a point Pbr2, respectively. By this correction control, the ECU 40 can more accurately calculate the throttle passing air amount mt even in the range of the throttle opening degree TA shown in the region Sbr.

<Description of flowchart>
Next, correction control executed by the CPU 42 of the ECU 40 (hereinafter also simply referred to as “CPU”) will be described with reference to the flowchart of FIG. Now, it is assumed that the relationship between the throttle opening degree TA and the throttle passing air amount mt is as shown by a curve Lb in FIG. 3A due to deposit adhesion on the throttle valve 12 and the inner wall of the intake pipe 11.

  While the engine 10 is operating, the CPU starts processing from step 400 every time a predetermined time elapses and proceeds to step 405. In step 405, the CPU determines the no-load idle opening degree TAm.

  More specifically, the CPU passes the throttle passing air calculated based on any two consecutive learned throttle openings TAs and a learned value (flow rate loss rate LRs) corresponding to these learned throttle openings TAs. The points corresponding to the amount mts are plotted on a graph representing the throttle passing air amount mt (y-axis) with respect to the throttle opening degree TA (x-axis), and the slope of the line segment obtained by connecting these points Is calculated. The CPU selects the smallest line segment in the range where the slope is equal to or greater than a predetermined threshold among the line segments corresponding to all two consecutive learning throttle opening degrees TAs, and moves the line segment to the small opening side. The throttle opening corresponding to the intersection of the extended (extrapolated) half line and the “straight line parallel to the x-axis representing the minimum inflow air amount mtm” is calculated as the no-load idle opening TAm. According to the above-mentioned assumption, the no-load idle opening degree TAm is TAmb.

  Next, the CPU proceeds to step 410 to acquire a flow rate loss rate LRr, which is a learning value corresponding to the learning throttle opening that is one opening larger than the no-load idle opening TAm. According to the above-described assumption, the flow rate loss rate LRr is a learning value Pbr3 corresponding to the learning throttle opening degree TA3 that is one opening degree larger than the no-load idle opening degree TAmb.

  Next, the CPU proceeds to step 415 to acquire a flow rate loss rate LR1 that is a learning value corresponding to the learning throttle opening that is one opening smaller than the no-load idle opening TAm. According to the above-described assumption, the flow rate loss rate LRl is the learning value Par2 corresponding to the learning throttle opening degree TA2 that is one opening smaller than the no-load idle opening degree TAmb. Since the learning value Par2 is included in the non-learning area as described above, the learning value Par2 remains unupdated.

  Next, the process proceeds to step 420, where the CPU has an error in the flow rate loss rate LR (and the throttle passing air amount mt calculated based on the flow loss rate LR) calculated by the ECU 40 due to the expansion of the learning impossible region described above. It is determined whether or not. Specifically, the CPU determines whether or not the learning value on the small opening side (flow rate loss rate LRl) is larger than the learning value on the large opening side (flow rate loss rate LRr). According to the above-mentioned assumption, the learning value Par2 is larger than the learning value Pbr3. In this case, the CPU makes a “Yes” determination at step 420 to proceed to step 425.

  In step 430, the CPU sets the learning value on the small opening side (flow rate loss rate LR) to a value equal to the learning value on the large opening side (flow rate loss rate LRr). According to the above assumption, the CPU sets the learned value Par1 and the learned value Par2 corresponding to the throttle opening TA on the smaller opening side than the no-load idle opening TAmb to be equal to the learned value Pbr3. That is, the learning value Par1 and the learning value Par2 are corrected to the point Pbr1 and the point Pbr2, respectively. Next, the CPU proceeds to step 495 to end the present routine tentatively.

  On the other hand, when the error of the throttle passage air amount mt due to the expansion of the learning impossible area described above has not occurred, for example, when deposit adhesion has not occurred, or immediately after this correction control has already been executed. In some cases, the flow rate loss rate LRl corresponding to the learned value on the small opening side is not larger than the flow rate loss rate LRr corresponding to the learned value on the large opening side. In such a case, the CPU makes a “No” determination at step 420, proceeds to step 495 without executing step 425, that is, without correcting the learning value, and once ends this routine.

As described above, the control unit (ECU 40) of the first device is
The relationship between the initial air amount that is the amount of air flowing through the intake pipe when there is no deposit (for example, deposit) on the intake pipe 11 and the throttle valve 12 of the internal combustion engine 10 and the throttle opening is stored in advance (FIG. 2). Curve A in (A))
The throttle opening for ensuring the amount of air necessary for the engine to maintain the no-load idle operation state is determined as the no-load idle opening (step 405 in FIG. 4),
The flow rate loss rate, which is the ratio of the actual air amount to the initial air amount, is obtained for the learning throttle opening determined for each predetermined throttle opening region, and the obtained flow loss rate is set to the learned throttle opening. Acquired as corresponding learning values (points Pir1 to Pir4 and points Par2 to Par4 in FIG. 2B, and points Pbr3 and Pbr4 in FIG. 3B),
The air amount corresponding to the throttle opening is calculated based on the learning value, and the calculated air amount is used for controlling the engine (the thick line Lam in FIG. 2A and the thick line in FIG. 3A). Lbm),
A control device for an internal combustion engine,
Of the learning throttle opening, the small opening side learning value that is the learning value corresponding to the maximum opening within a range smaller than the determined no-load idle opening is the same as the learning throttle opening. When larger than the large opening side learning value, which is the learning value corresponding to the minimum opening within a range larger than the no-load idle opening (step 420 in FIGS. 2B and 3B and FIG. 4). ), The same small opening side learning value is set to a value corresponding to the same large opening side learning value (point Par1 in FIG. 2B, point Pbr1 and point Pbr2 in FIG. 3B, and 4 step 425).

  According to the first device, when deposit adheres to the throttle valve 12 and the inner wall of the intake pipe 11, the throttle opening degree TA is in the vicinity of the no-load idle opening degree TAm or slightly larger than that. However, the throttle passage air amount mt corresponding to the throttle opening degree TA can be calculated more accurately. Therefore, even in such a case, the first device can maintain the air-fuel ratio in the vicinity of the target value, and can avoid a decrease in the fuel consumption rate and a deterioration in the exhaust emission.

Second Embodiment
Next, an internal combustion engine control apparatus (hereinafter also referred to as “second apparatus”) according to a second embodiment of the present invention will be described. When correcting the learning value, the first device reflects the “learning value on the large opening side (flow rate loss rate LRr)” on the learning value on the small opening side with respect to the no-load idle opening degree TAm. On the other hand, when the second device corrects the learning value, “the difference between the throttle passing air amount mt corresponding to the learning throttle opening on the large opening side and the initial inflow air amount mti” is set on the small opening side. It differs from the first device only in that it is reflected in the learning value. Hereinafter, this difference will be mainly described.

  Regarding the “correction control” executed by the ECU 41 according to the second device, it is assumed that the relationship between the throttle opening degree TA and the throttle passage air amount mt is as shown by the curve La in FIG. I will explain.

  When the ECU 41 determines that the above-described error has occurred in the calculated throttle passing air amount mt (that is, when LRl> LRr), the ECU 41 executes “correction control”. More specifically, the ECU 41 corresponds to the minimum learned throttle opening in the region on the larger opening side than the “no load idle opening TAm” and “the initial inflow air amount mti corresponding to the learned throttle opening”. The difference (decrease amount) with the throttle passage air amount mt "is calculated. In this example, the ECU 41 determines from “Pi2 which is an initial inflow air amount corresponding to TA2 which is in the region of the larger opening degree than the no-load idle opening degree TAma and which is the minimum learning throttle opening degree” to “Learning throttle opening degree”. A difference Δmt is calculated by subtracting Pa2 which is the amount of air passing through the throttle corresponding to TA2.

  Next, the ECU 41 corrects the learned value on the smaller opening side than the no-load idle opening degree TAm so that the difference between the initial inflow air amount mti and the throttle passing air amount mt corresponding to these learned values becomes equal to Δmt. To do. In this example, the ECU 41 sets the initial inflow air amount Pi1 corresponding to the learning throttle opening degree TA1 that is smaller than the no-load idle opening degree TAm (the point Pi1 is in the learning disabled region, so The point Pc1 (throttle passage air amount) obtained by subtracting Δmt from the above is calculated. Next, the ECU 40 calculates a flow rate loss rate LR (point Pcr1) that is a ratio of Pc1 to Pi1, and stores the value in the backup RAM 45 as a corrected learned value.

  As a result, the ECU 41 is obtained by connecting the point Pcr1 which is the corrected learning value and the points Par2 to Par4 which are the learning values (updated by the normal learning process) (that is, the learning values are linearly interpolated). The flow rate loss rate LR corresponding to the throttle opening degree TA is calculated based on the thick line Lcmr (obtained as described above). In other words, the throttle passing air amount mt corresponding to the throttle opening degree TA calculated by the ECU 41 is indicated by the thick line Lcm obtained by connecting the points Pc1 and Pa2 to Pa4 in FIG.

  Next, “correction control” executed by the CPU 42 of the ECU 41 (hereinafter also simply referred to as “CPU”) will be described with reference to the flowchart of FIG. Steps in the flowchart of FIG. 6 in which the same processing as the steps shown in FIG. 4 is executed are denoted by the same step symbols as in FIG. The CPU starts processing from step 600 every time a predetermined time elapses, performs the processing from step 405 to step 415, and proceeds to step 420.

  If the flow rate loss rate LR1 corresponding to the learned value on the small opening side is larger than the flow rate loss rate LRr corresponding to the learned value on the large opening side, the CPU determines “Yes” in step 420 and proceeds to step 625. move on. On the other hand, if this condition is not satisfied, the CPU makes a “No” determination at step 420 to proceed to step 695 to end the present routine tentatively.

  In step 625, the CPU determines that “the initial inflow air amount mti corresponding to the minimum learned throttle opening TA in a range larger than the no-load idle opening TAm” and “learning corresponding to the same throttle opening TA”. Δmt, which is the difference from the throttle passage air amount mt calculated based on the value, is calculated.

  Next, the CPU proceeds to step 630 to correct the learning value corresponding to the learning throttle opening that is smaller than the no-load idle opening TAm. More specifically, the CPU makes the difference between “the initial inflow air amount mti corresponding to those learning values” and “the throttle passage air amount mt corresponding to those throttle opening TA” equal to Δmt. The flow rate loss rate LR is calculated (that is, LR = (mti−Δmt) / mti). Next, the CPU proceeds to step 695 to end the present routine tentatively.

  As described above, according to the second device, when deposit adheres to the inner wall of the throttle valve 12 and the intake pipe 11, the throttle opening degree TA is close to or more than the opening degree TAm in the no-load idle state. Even when is slightly larger, it is possible to more accurately calculate the throttle passage air amount mt corresponding to the throttle opening degree TA. Therefore, the second device can maintain the air-fuel ratio in the vicinity of the target value even in such a case, and can avoid a decrease in the fuel consumption rate and a deterioration in the exhaust emission.

  As mentioned above, although each embodiment of the control apparatus which concerns on this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the objective of this invention. For example, in each embodiment, the vehicle is equipped with the engine 10 for driving. However, this vehicle may be further equipped with an electric motor for driving. That is, this vehicle may be a hybrid car.

  In addition, the ECU according to each embodiment calculates the no-load idle opening degree TAm based on the slope of a line segment obtained by connecting two learning values corresponding to the corresponding throttle opening degree TA. However, each ECU may calculate the no-load idle opening degree TAm by other methods. For example, each ECU plots points corresponding to a plurality of learning values on a graph representing a throttle passing air amount mt (y axis) with respect to the throttle opening degree TA (x axis) and obtains them by connecting them. The throttle opening degree TA corresponding to the intersection of the “spline curve” and the “straight line parallel to the x-axis representing the minimum inflow air amount mtm” may be calculated as TAm. Alternatively, each ECU corresponds to the “learning throttle opening corresponding to the learning value that has not been updated for a longer period than the predetermined period” and “the learning value that has been updated, based on the last update time of each learning value. The throttle opening between the “learning throttle opening” may be determined as the no-load idle opening TAm. Alternatively, each ECU stores a plurality of combinations of the flow characteristic value corresponding to the degree of deposit adhesion and the no-load idle opening degree in the ROM 43 in advance as an expected pattern, and the most appropriate pattern from the actual learning value at that point in time. It is also possible to select whether they are similar and determine the no-load idle opening corresponding to the pattern as TAm.

  Alternatively, the ECU according to each embodiment calculates the flow rate loss rate LR corresponding to the actual throttle opening TA by linear interpolation of the learning values corresponding to two consecutive learning throttle openings. However, each ECU may calculate the flow rate loss rate LR by other methods. For example, each ECU plots “three or more consecutive learning throttle openings and learning values corresponding to the learning throttle openings as points on the graph, and a spline curve obtained by connecting these points” The flow rate loss rate LR may be calculated as a value corresponding to.

  Alternatively, the ECU according to each embodiment stores a learning value for each fixed learning throttle opening included in each opening region. However, each ECU may store a learning value for each learning throttle opening that varies within each opening region.

  Alternatively, the ECU according to each embodiment corrects all the learning values on the smaller opening side than the no-load idle opening degree TAm when correcting the learning value. However, each ECU has a learning value that is one opening smaller than the no-load idle opening TAm (that is, a learning value corresponding to the maximum throttle opening in a range where the throttle opening is smaller than the throttle opening TAm). You may correct only.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake pipe, 12 ... Throttle valve, 21 ... Combustion chamber, 31 ... Exhaust pipe, 40 ... ECU, 51 ... Air quantity sensor.

Claims (1)

Storing in advance the relationship between the initial air amount, which is the amount of air flowing through the intake pipe when there is no deposit on the intake pipe and the throttle valve of the internal combustion engine, and the throttle opening;
The throttle opening for ensuring the amount of air necessary for the engine to maintain the no-load idle operation state is determined as the no-load idle opening,
The flow rate loss rate, which is the ratio of the actual air amount to the initial air amount, is obtained for the learning throttle opening determined for each predetermined throttle opening region, and the obtained flow loss rate is set to the learned throttle opening. Obtained as the corresponding learning value,
Calculating the air amount corresponding to the throttle opening based on the learning value and using the calculated air amount for controlling the engine;
In a control device for an internal combustion engine,
Of the learning throttle opening, the small opening side learning value that is the learning value corresponding to the maximum opening within a range smaller than the determined no-load idle opening is the same as the learning throttle opening. If the learned value corresponding to the smallest opening in the range larger than the no-load idle opening is larger than the learned value on the larger opening side, the learned value on the smaller opening side is set according to the learned value on the larger opening side. Control device to set to value.

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