JP5555496B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine control apparatus for controlling the operation of an internal combustion engine having a plurality of cylinders.

  Conventionally, as a control device for this type of internal combustion engine, for example, one disclosed in Patent Document 1 is known. In this control device, the air-fuel ratio is controlled for each cylinder in order to suppress the air-fuel ratio of the air-fuel mixture supplied to the plurality of cylinders from varying among the cylinders. Specifically, the air-fuel ratio of the exhaust gas flowing through the collective portion of the exhaust pipe connected to the plurality of cylinders is detected by a sensor, and based on the detected air-fuel ratio of the exhaust gas, the Kalman filter type observer is configured. In accordance with the model formula, an estimated value of the air-fuel ratio of the supplied air-fuel mixture (hereinafter referred to as “estimated air-fuel ratio”) is calculated for each cylinder. Further, the average value of the estimated air-fuel ratios of a plurality of cylinders is calculated as the reference air-fuel ratio, and the air-fuel ratio for each cylinder is set so that the deviation between the calculated reference air-fuel ratio and the estimated air-fuel ratio of each cylinder becomes small. A correction amount is calculated for each cylinder. The fuel injection amount is controlled for each cylinder in accordance with the calculated cylinder-by-cylinder air-fuel ratio correction amount.

  The internal combustion engine is also provided with an evaporated fuel processing device for supplying evaporated fuel in the fuel tank to the intake pipe. In the above-described conventional control device, when the cylinder-by-cylinder air-fuel ratio correction amount corresponding to one of the cylinders is out of the predetermined range, in order to prevent the variation in the air-fuel ratio between the cylinders from further increasing, The supply of evaporated fuel by the processing device is prohibited.

JP 2008-38785 A

  As described above, in the conventional control device, the estimated air-fuel ratio is calculated for each cylinder according to a complicated model equation in order to control the air-fuel ratio for each cylinder in order to suppress variation in the air-fuel ratio between the cylinders. The calculation load increases. In addition, when the air-fuel ratio correction amount for each cylinder is out of the predetermined range, it is prohibited to supply the evaporated fuel to the intake pipe, so the amount of evaporated fuel in the fuel tank or the evaporated fuel processing device becomes excessive, and the fuel There is a risk of failure of the tank or the evaporated fuel processing device.

  The present invention has been made to solve the above-described problems, and is an internal combustion engine that can easily suppress variation in air-fuel ratio among a plurality of cylinders while supplying evaporated fuel to the plurality of cylinders. An object of the present invention is to provide a control device.

In order to achieve the above object, an internal combustion engine control apparatus 1 according to the invention according to claim 1 is provided for each of a plurality of cylinders (# 1 to # 4 cylinders 3a in the embodiment (hereinafter the same in this section)). A variable lift device (variable lift mechanism 14, ECU 2) capable of changing the amount of intake air taken into a plurality of cylinders via the intake system (intake pipe 6) by changing the lift of the provided intake valve 5; An evaporative fuel processing device 16 for supplying evaporative fuel generated in the fuel tank FT to a plurality of cylinders via an intake system, and lift detecting means for detecting the lift of the intake valve 5 (rotation angle sensor 23, ECU 2) And evaporative fuel control for performing evaporative fuel control for controlling the amount of evaporative fuel supplied from the evaporative fuel processing device 16 to the intake system in accordance with the detected lift of the intake valve (valve lift Liftin) Stage (ECU 2, step 3, 4) and provided with a fuel vapor control means, the amount of to the amount of intake air flowing through the intake system (intake air flow rate QA), evaporative fuel supplied to the intake system from the fuel vapor processing apparatus 16 The target purge rate KQPGB which is the target of the ratio is set to a larger value as the lift of the intake valve 5 is smaller (step 3, FIG. 5), and the evaporated fuel control is performed based on the set target purge rate KQPGB. It executes (step 4) .

  According to this configuration, the amount of intake air drawn into the plurality of cylinders via the intake system is changed by changing the lift of the intake valves provided in each of the plurality of cylinders by the variable lift device. The Further, the evaporated fuel generated in the fuel tank is supplied to the plurality of cylinders via the intake system by the evaporated fuel processing device. It should be noted that “lift of intake valve” in the claims and in this specification represents the maximum lift of the intake valve.

  In the internal combustion engine provided with the variable lift device as described above, the intake air amount may vary due to variations in the intake characteristics of the internal combustion engine and the operating characteristics of the variable lift device due to secular change among a plurality of cylinders. In that case, the air-fuel ratio of the air-fuel mixture supplied to the cylinder also varies, and consequently the output torque of the internal combustion engine varies. Here, FIGS. 7A and 7B show the variation in the air-fuel ratio between the four first to fourth cylinders generated as described above when the intake valve lift is small and large. For each. As shown in FIG. 7, the smaller the intake valve lift, the smaller the amount of intake air sucked into each cylinder, and the larger the ratio of variation due to variation to this amount of intake air, the more the air-fuel ratio between the cylinders. The variation becomes large. Further, in the internal combustion engine provided with the evaporative fuel processing device as described above in addition to the variable lift device, the evaporative fuel is supplied to a plurality of cylinders via the intake system when the above-described variation in intake air amount occurs. Since the fuel is supplied, the amount of the evaporated fuel supplied also varies between the cylinders in the same tendency as the intake air amount. Specifically, the amount of fuel vapor to be supplied varies on the small side when the intake air amount varies to the small side, and varies on the large side when the cylinder shifts to the large side.

  For this reason, if the evaporated fuel is supplied to the plurality of cylinders when the intake air amount varies, the air-fuel ratio varies toward the lean side (fuel lean) side due to variations in the intake air amount. A larger amount of evaporated fuel is supplied to the cylinders that vary (hereinafter referred to as “lean side variation cylinders”). As a result, the air-fuel ratio of the lean side variation cylinders is relatively large on the rich (fuel rich) side. Change. On the other hand, a smaller amount of evaporated fuel is supplied to a cylinder in which the air-fuel ratio varies to the rich side (hereinafter referred to as “rich variation cylinder”) by varying the intake air amount to the smaller side, and as a result, the rich side The air-fuel ratio of the variation cylinder changes relatively small toward the rich side. As described above, as the evaporative fuel is supplied, the air-fuel ratio of the lean-side variation cylinder changes to the rich side larger than the air-fuel ratio of the rich-side variation cylinder. It acts to suppress variations in the air-fuel ratio between the two.

  Therefore, unlike the conventional case described above, only by supplying the evaporated fuel by the evaporated fuel processing device, the fuel injection control based on the complicated model formula is not performed for each cylinder, and the variation of the air-fuel ratio among the plurality of cylinders is reduced. This can be easily suppressed, and consequently, the output torque of the internal combustion engine can be suppressed from varying between the cylinders. Further, since the fuel tank can be executed without prohibiting the supply of the evaporated fuel, the fuel tank and the evaporated fuel processing apparatus do not break down.

  Furthermore, as described above, when the operation characteristics of the variable lift device vary among the cylinders, the magnitude of the variation in the air-fuel ratio at that time varies depending on the lift of the intake valve. According to the configuration described above, such lift of the intake valve is detected, and the amount of evaporated fuel supplied to the intake system is controlled according to the detected lift of the intake valve. Therefore, the amount of the evaporated fuel supplied to the plurality of cylinders via the intake system can be appropriately controlled according to the magnitude of the variation in the air-fuel ratio between the cylinders. Can be suppressed appropriately. Note that “detection” in the claims and in this specification includes calculation and estimation by calculation in addition to direct detection by a sensor or the like.

Further, as described with reference to FIG. 7, when the intake air amount varies between the cylinders, the smaller the intake valve lift, the larger the ratio of the variation due to the variation to the intake air amount of each cylinder. The variation in air-fuel ratio between cylinders becomes large. According to the above-described configuration, the target purge rate, which is the target of the ratio of the amount of evaporated fuel supplied from the evaporated fuel processing device to the intake system with respect to the amount of intake air flowing through the intake system, is smaller as the lift of the intake valve is smaller. Since the value is set to a larger value, the amount of evaporated fuel supplied to the plurality of cylinders can be controlled to a value commensurate with the amount of fluctuation due to variations in the intake air amount. Variation can be reliably suppressed.

It is a figure showing roughly the internal-combustion engine to which the control device by this embodiment is applied. It is sectional drawing which shows a part of internal combustion engine shown in FIG. It is a block diagram which shows ECU etc. of the control apparatus by this embodiment. It is a flowchart which shows the evaporative fuel control process performed by ECU shown in FIG. It is an example of the map used by the evaporative fuel control process shown in FIG. It is a figure which shows the operation example of the control apparatus shown in FIG. It is a figure which shows the dispersion | variation in the air fuel ratio between the 1st-4th cylinder, respectively about (a) when the lift of an intake valve is small, and (b) when the lift of an intake valve is large.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 show an internal combustion engine (hereinafter referred to as “engine”) 3 to which a control device 1 according to the present embodiment is applied. The engine 3 is a gasoline engine mounted on a vehicle (not shown), and includes four # 1 to # 4 cylinders 3a, and a fuel injection valve 4 and an intake valve 5 provided for each cylinder 3a. (Only one is shown in FIG. 2). The fuel injection valve 4 is connected to the fuel tank FT via a pump (not shown) or the like, and directly injects the fuel in the fuel tank FT into the corresponding cylinder 3a. That is, the engine 3 is configured as a direct injection engine. Further, the valve opening time of the fuel injection valve 4 is controlled by an ECU 2 described later of the control device 1 (see FIG. 3).

  The engine 3 is provided with a crank angle sensor 21 and a water temperature sensor 22. The crank angle sensor 21 includes a magnet rotor and an MRE pickup, and outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft (not shown) of the engine 3 rotates.

  The CRK signal is output at every predetermined crank angle, and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly before the TDC position at the start of the intake stroke. The water temperature sensor 22 is a thermistor and detects the engine water temperature TW, which is the temperature of the cooling water circulating in the main body of the engine 3, and outputs a detection signal to the ECU 2.

  As shown in FIGS. 1 and 2, the engine 3 is provided with an intake valve mechanism 11. The intake valve mechanism 11 is for opening and closing the intake valve 5, and includes an intake camshaft 12, an intake cam 13, and a variable lift mechanism 14. The intake camshaft 12 is connected to a crankshaft via a timing belt (not shown). As a result, the intake camshaft 12 rotates once every time the crankshaft rotates twice. The intake cam 13 is provided integrally with the intake camshaft 12 for each cylinder 3a.

  The variable lift mechanism 14 opens and closes the intake valve 5 as the intake cam 13 rotates, and changes the lift (hereinafter referred to as “valve lift”) Liftin of the intake valve 5 to change the # 1 to # 4 cylinders 3a. The amount of intake air sucked in can be changed. In the present embodiment, the valve lift Liftin represents the maximum lift of the intake valve 5. The variable lift mechanism 14 includes a four-bar link type rocker arm mechanism 14a provided for each cylinder 3a, and a lift actuator 14b (see FIG. 3) for simultaneously driving these rocker arm mechanisms 14a. Since the variable lift mechanism 14 is configured in the same manner as that disclosed in Japanese Patent No. 4300369, the description of the configuration is omitted, and the operation when changing the valve lift Liftin will be briefly described below. explain.

  In the variable lift mechanism 14, the lift actuator 14b has a short arm (not shown) connected to the rocker arm mechanism 14a. By rotating the short arm, the rocker arm mechanism 14a is driven. The valve lift Liftin is changed steplessly. In this case, by inputting a lift control input (described later) from the ECU 2 to the lift actuator 14b, the valve lift Liftin is controlled by changing the rotation angle of the short arm, and consequently the intake air amount is controlled. .

  Further, the engine 3 is provided with a rotation angle sensor 23 (see FIG. 3). The rotation angle sensor 23 detects the rotation angle θlift of the short arm of the lift actuator 14b, and the detection signal thereof. Is output to the ECU 2. As described above, since the valve lift Liftin changes according to the rotation angle θlift of the short arm, the ECU 2 calculates the valve lift Liftin based on the rotation angle θlift.

  Further, intake pipes 6 for introducing intake air into the respective cylinders 3a are connected to the four # 1 to # 4 cylinders 3a through four branch portions of the intake manifold 6a. In addition, a throttle valve 15 is provided in the intake pipe 6, and a TH actuator 15 a constituted by an electric motor is connected to the throttle valve 15. The opening degree of the throttle valve 15 is controlled by changing the duty ratio of the current flowing through the TH actuator 15a by the ECU 2.

  An air flow sensor 24 is provided upstream of the throttle valve 15 in the intake pipe 6. The air flow sensor 24 is constituted by a hot-wire air flow meter, detects the amount of intake air flowing through the intake pipe 6 (hereinafter referred to as “intake flow rate”) QA, and outputs a detection signal to the ECU 2.

  Further, the engine 3 is provided with an evaporated fuel processing device 16. This evaporative fuel processing device 16 is for supplying the evaporative fuel generated in the fuel tank FT to the # 1 to # 4 cylinders 3a via the intake pipe 6, and is disclosed in Japanese Patent No. 384749. Therefore, the configuration and operation will be briefly described below.

  The evaporated fuel processing device 16 has a canister (not shown) and a purge control valve 16a (see FIG. 3). The canister is connected to the fuel tank FT, and is connected downstream of the throttle valve 15 in the intake pipe 6 and upstream of the intake manifold 6a. The evaporated fuel is temporarily adsorbed by the canister and then sent (purged) to the intake pipe 6 by the negative pressure in the intake pipe 6. In this case, the flow rate of the evaporated fuel purged from the canister to the intake pipe 6 (hereinafter referred to as “purge flow rate”) is controlled by controlling the opening degree of the purge control valve 16 a by the ECU 2.

  Further, exhaust pipes 7 are connected to the four # 1 to # 4 cylinders 3a through four branch portions of the exhaust manifold 7a, respectively. Furthermore, the LAF sensor 25 is attached to the exhaust pipe 7 on the downstream side of the gathering portion where these branch portions gather. The LAF sensor 25 linearly detects the oxygen concentration in the exhaust gas and outputs a detection signal to the ECU 2. Based on this detection signal, the ECU 2 calculates an actual air-fuel ratio that represents the air-fuel ratio of the air-fuel mixture burned in the cylinder 3a.

  Further, a detection signal representing an operation amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle is output from the accelerator opening sensor 26 to the ECU 2.

  The ECU 2 is composed of a microcomputer including a CPU, a RAM, a ROM, an I / O interface (all not shown), and the like. The ECU 2 controls operations of the engine 3, the variable lift mechanism 14, and the evaporated fuel processing device 16 according to a control program stored in the ROM in accordance with detection signals from the various sensors 21 to 26 described above.

  Specifically, the ECU 2 controls the intake air amount as follows by controlling the operation of the variable lift mechanism 14. That is, first, a target valve lift is calculated by searching a predetermined map (not shown) according to the calculated engine speed and the detected accelerator pedal opening AP. Next, the aforementioned lift control input is calculated by a predetermined feedback control algorithm so that the calculated valve lift Liftin becomes the target valve lift, and the calculated lift control input is output to the lift actuator 16b. Thus, feedback control is performed so that the valve lift Liftin becomes the target valve lift, and consequently, the intake air amount is controlled.

  Further, the fuel injection amount by the fuel injection valve 4 is controlled as follows. That is, the basic fuel injection time is calculated by searching a predetermined map (not shown) according to the detected intake flow rate QA. Next, an air-fuel ratio correction coefficient is calculated by a predetermined feedback control algorithm so that the calculated actual air-fuel ratio becomes a predetermined target air-fuel ratio A / FOBJ. This target air-fuel ratio A / FOBJ is set to, for example, the theoretical air-fuel ratio (value 14.7).

  Next, the final fuel injection time is calculated by correcting the basic fuel injection time according to the calculated air-fuel ratio correction coefficient and various correction terms, and control based on the calculated final fuel injection time. A signal is output to the fuel injection valve 4. Accordingly, the fuel injection amount injected from the fuel injection valve 4 is controlled by controlling the valve opening time of the fuel injection valve 4 to be the final fuel injection time, and is supplied to each cylinder 3a. Feedback control is performed so that the air-fuel ratio of the mixture becomes the target air-fuel ratio. The air-fuel ratio feedback control (hereinafter referred to as “air-fuel ratio F / B control”) by controlling the fuel injection amount described above is performed when the operating state of the engine 3 represented by the engine speed, the accelerator pedal opening AP, etc. is predetermined. Executed when in operation.

Further, according to the evaporated fuel control process shown in FIG. 4, the operation of the evaporated fuel processing device 16 is controlled as follows. First, in step 1 of FIG. 4 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the purge execution flag F_PURGEOK is “1”. The purge execution flag F_PURGEOK assumes that the purge execution condition for purging the evaporated fuel adsorbed to the canister of the evaporated fuel processing device 16 is satisfied when all of the following conditions a to c are satisfied: Set to “1”.
a: The detected engine water temperature TW is higher than a predetermined temperature. The predetermined temperature is set to a temperature at which the engine water temperature TW can be determined to be relatively high, for example, 65 ° C.
b: The air-fuel ratio F / B control described above is being executed.
c: The fuel cut operation accompanying the deceleration operation of the engine 3 is not being performed.

  When the answer to step 1 is NO, that is, when the above-described purge execution condition is not satisfied, the target purge flow rate QPGCBASE is set to 0 (step 2), and this process ends. This target purge flow rate QPGCBASE is the above-described purge flow rate, that is, the target value of the flow rate of the evaporated fuel purged into the intake pipe 6. By executing this step 2, the purge control valve 16a is controlled to be in a fully closed state, whereby the purge flow rate is controlled to be 0.

  On the other hand, when the answer to step 1 is YES and the purge execution condition is satisfied, the target purge rate KQPGB is calculated by searching the map shown in FIG. 5 according to the valve lift Liftin (step 3). This target purge rate KQPGB is a target value of the ratio of the purge flow rate to the intake flow rate QA, and in this map, it is set to a larger value as the valve lift Liftin is smaller. As described with reference to FIG. 7, the smaller the valve lift Liftin, the smaller the intake air amount of each cylinder 3a, and the larger the ratio of the fluctuation amount due to the variation to this intake air amount, the four # This is because the variation in the air-fuel ratio among the first to # 4 cylinders 3a becomes large, so that the purge flow rate is controlled to a size commensurate with the variation due to the variation in the intake air amount.

  Next, the target purge flow rate QPGCBASE is calculated by multiplying the intake flow rate QA by the target purge rate KQPGB calculated in step 3 (step 4), and this processing is terminated. By performing step 4, the opening of the purge control valve 16a is controlled, so that the purge flow rate is controlled to become the target purge flow rate QPGCBASE.

  FIG. 6 shows that the intake air amount varies between the # 1 and # 4 cylinders 3a due to changes over time in the intake characteristics of the engine 3 and the operating characteristics of the variable lift mechanism 14, and so on. In the case where there are variations on the larger side and the smaller side in the # 3 cylinder 3a and the # 4 cylinder 3a, respectively, and the valve lift Liftin is relatively small, the air-fuel ratio F / B control described above and An operation example when the evaporated fuel control process is executed is shown.

  In FIG. 6, A / F # 1a, A / F # 2a, A / F # 3a, and A / F # 4a are each executing the air-fuel ratio F / B control and before executing the evaporated fuel control process. At the air-fuel ratios of cylinders # 1 to # 4 (hereinafter referred to as “# 1 air-fuel ratio before purge”, “# 2 air-fuel ratio before purge”, “# 3 air-fuel ratio before purge”, “# 4 air-fuel ratio before purge”, respectively). is there. A / F # 1b, A / F # 2b, A / F # 3b, and A / F # 4b are stabilized immediately after the execution of the evaporated fuel control process and the air-fuel ratio is stabilized by the air-fuel ratio F / B control. The air-fuel ratios of the cylinders # 1 to # 4 (hereinafter referred to as “# 1 air-fuel ratio immediately after purge”, “# 2 air-fuel ratio immediately after purge”, “# 3 air-fuel ratio immediately after purge”, “# 4 air-fuel ratio immediately after purge”) ). Further, A / F # 1c, A / F # 2c, A / F # 3c, and A / F # 4c are stabilized after the execution of the evaporated fuel control process and by the air / fuel ratio F / B control. The air-fuel ratios of the # 1 to # 4 cylinders 3a in the same state (hereinafter referred to as "after # 1F / B air-fuel ratio", "after # 2F / B air-fuel ratio", "# 3F / B after-air ratio", "after # 4F / B respectively" Air-fuel ratio).

  As described above, the oxygen concentration in the exhaust gas flowing downstream from the collecting portion in the exhaust pipe 7, that is, the oxygen concentration in the exhaust gas mixed with each other discharged from the # 1 to # 4 cylinders 3a, respectively. The air-fuel ratio F / B control is executed in accordance with the actual air-fuel ratio that is detected by the LAF sensor 25 and calculated based on the detected value. For this reason, when the air-fuel ratio varies due to variations in the operational characteristics of the variable lift mechanism 14 due to secular change between the cylinders 3a, the air-fuel ratio F / B control alone is not sufficient between such cylinders 3a. Variations in air-fuel ratio cannot be suppressed.

  In this operation example, as described above, the intake air amount varies on the larger side in the # 1 cylinder 3a and the # 2 cylinder 3a and on the smaller side in the # 3 cylinder 3a and the # 4 cylinder 3a. And # 2 pre-purge air / fuel ratios A / F # 1a and A / F # 2a vary toward the lean side of the target air / fuel ratio A / FOBJ (fuel lean), and # 3 and # 4 pre-purge air / fuel ratios A / F # 3a and A / F # 4a vary more on the rich (fuel rich) side than the target air-fuel ratio A / FOBJ. Further, as described above, since the valve lift Liftin is small, the intake air amount of each cylinder 3a is small, and the ratio of the fluctuation amount due to the variation to the intake air amount is large, so the variation of the air-fuel ratio between the cylinders 3a is large. . Further, by the air-fuel ratio F / B control, the average value of the # 1 to # 4 pre-purging air-fuel ratios A / F # 1a to A / F # 4a is substantially the target air-fuel ratio A / FOBJ.

  Further, when the evaporated fuel control process is executed in addition to the air-fuel ratio F / B control, the evaporated fuel is supplied to the # 1 to # 4 cylinders 3a, so that the air-fuel ratio A / F immediately after the # 1 to # 4 purges. # 1 to A / F # 4b change to the rich side as a whole. In this case, since the evaporated fuel is supplied to the cylinder 3a through the intake pipe 6 as described above, the amount of supplied evaporated fuel varies between the cylinders 3a in the same tendency as the intake air amount. A larger amount of evaporated fuel is supplied to the cylinder 3a and the # 2 cylinder 3a, while a smaller amount of evaporated fuel is supplied to the # 3 cylinder 3a and the # 4 cylinder 3a. As a result, the air / fuel ratios A / F # 1b and A / F # 2b immediately after the purges # 1 and # 2 change to a relatively large rich side, while the air / fuel ratios A / F # 3b, immediately after the purges # 3 and # 4, A / F # 4b is relatively small and changes to the rich side. As described above, the air-fuel ratios A / F # 1b to A / F # 4b immediately after the purges # 1 to # 4 have less variation between the cylinders 3a than before the execution of the evaporated fuel control process. The average value is shifted to the rich side from the target air-fuel ratio A / FOBJ.

  In addition, after the execution of the evaporated fuel control process, the air-fuel ratios A / F # 1b to A / F # 4b immediately after the purges # 1 to # 4, which have changed to the rich side as described above, are changed by the air-fuel ratio F / B control. After the change to the lean side as a whole, it stabilizes. In this operation example, the average value of the post- # 1 to # 4F / B air-fuel ratios A / F # 1c to A / F # 4c is substantially the target air-fuel ratio A / FOBJ. In addition, it is clear by comparing # 1 to # 4F / B post-air-fuel ratios A / F # 1c to A / F # 4c and # 1 to # 4 pre-purge air / fuel ratios A / F # 1a to A / F # 4a Thus, the variation in the air-fuel ratio between the cylinders 3a is small.

  The correspondence between various elements in the present embodiment and various elements in the present invention is as follows. That is, the intake pipe 6 in the present embodiment corresponds to the intake system in the present invention, and the variable lift mechanism 14 and the ECU 2 in the present embodiment correspond to the variable lift device in the present invention. Further, the rotation angle sensor 23 and the ECU 2 in the present embodiment correspond to the lift detection means in the present invention, and the ECU 2 in the present embodiment corresponds to the evaporated fuel control means in the present invention.

  As described above, according to the present embodiment, the lift of the intake valve 5 provided in each of the four # 1 to # 4 cylinders 3 a is changed by the variable lift mechanism 14, thereby allowing the intake pipe 6 to pass through the intake pipe 6. Thus, the intake air amount sucked into the cylinders # 1 to # 4 is changed. Further, the evaporated fuel processing device 16 supplies evaporated fuel to the cylinder 3 a via the intake pipe 6. Furthermore, since the target purge rate KQPGB, which is the target value of the ratio of the purge flow rate to the intake flow rate QA, is set to a larger value as the valve lift Liftin is smaller, the purge flow rate is changed to a fluctuation amount due to variations in the intake air amount. It can be controlled to an appropriate size. Therefore, variation in the air-fuel ratio between the cylinders 3a can be reliably suppressed, and consequently, the output torque of the engine 3 can be suppressed from varying between the cylinders 3a.

  In addition, unlike the above-described conventional case, only by supplying the evaporated fuel by the evaporated fuel processing device 16, the fuel injection control based on the complicated model formula is not performed for each cylinder 3a, and the variation in the air-fuel ratio between the cylinders 3a. Can be easily suppressed. Further, since the fuel is directly injected into the corresponding cylinder 3a by the fuel injection valve 4, an appropriate amount of fuel is supplied to the cylinder without being affected by variations in the operating characteristics of the variable lift mechanism 14 between the cylinders 3a. 3a can be supplied.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, as the variable lift device according to the present invention, the variable lift mechanism 14 that changes the valve lift Liftin of each of the # 1 to # 4 cylinders 3a to the same size using a single lift actuator 14b. Although it is used, a variable lift device that can change the valve lift independently among a plurality of cylinders, for example, a variable lift device that opens and closes the intake valve of each cylinder with an electromagnetic actuator provided for each cylinder is used. May be. In the embodiment, the valve lift Liftin is calculated based on the detected rotation angle θlift. However, the valve lift Liftin may be directly detected by a proximity sensor or the like provided in the vicinity of the intake valve 5.

  Further, in the embodiment, the target purge rate KQPGB is calculated once according to the valve lift Liftin, and the purge flow rate is controlled according to the target purge flow rate QPGCBASE calculated based on the target purge rate KQPGB. However, if the purge flow rate is controlled in accordance with the valve lift Liftin according to the technical point of view described with reference to FIG. 7, another appropriate method may be used. For example, without calculating the target purge rate KQPGB, the target purge flow rate QPGCBASE is directly calculated according to the valve lift Liftin, and the purge flow rate is controlled according to the target purge flow rate QPGCBASE calculated as such. Also good. Alternatively, the purge flow rate is controlled by calculating the target value of the purge control valve 16a according to the valve lift Liftin and controlling the purge control valve 16a so that the opening of the purge control valve 16a becomes the calculated target value. You may go.

  The embodiment is an example in which the number of cylinders 3a is four, but the number is not limited to this as long as it is plural, and is arbitrary. Furthermore, although embodiment is the example which applied the control apparatus 1 to the engine 3 which is a gasoline engine of the type which injects a fuel directly in the cylinder 3a, the control apparatus 1 is not restricted to this, and is an intake port. Applicable to various types of industrial internal combustion engines such as injection engines, diesel engines, CNG (Compressed Natural Gas) engines, and marine vessel propulsion engines such as outboard motors with crankshafts arranged vertically. It is. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

1 Control device
2 ECU (variable lift device, lift detection means, evaporated fuel control means)
3 Engine 3a # 1 to # 4 cylinder
5 Intake valve
6 Intake pipe (intake system)
FT Fuel tank 14 Variable lift mechanism (variable lift device)
16 Evaporated fuel processing device 23 Rotation angle sensor (lift detection means)
Liftin valve lift (intake valve lift)
QA Intake flow rate (amount of intake air flowing through the intake system)
KQPGB target purge rate

Claims (1)

A variable lift device capable of changing the amount of intake air drawn into the plurality of cylinders via an intake system by changing the lift of an intake valve provided in each of the plurality of cylinders;
An evaporative fuel processing device for supplying evaporative fuel generated in a fuel tank to the plurality of cylinders via the intake system;
Lift detecting means for detecting the lift of the intake valve;
Evaporative fuel control means for performing evaporative fuel control for controlling the amount of evaporative fuel supplied from the evaporative fuel processing device to the intake system according to the detected lift of the intake valve , and
The evaporated fuel control means sets a target purge rate, which is a target of the ratio of the amount of evaporated fuel supplied from the evaporated fuel processing device to the intake system with respect to the amount of intake air flowing through the intake system, as a lift of the intake valve. A control device for an internal combustion engine, wherein the smaller the value is, the larger the value is set, and the evaporated fuel control is executed based on the set target purge rate .

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