JP4396253B2 - Intake control device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake control device for an internal combustion engine, and in particular, has an intake control valve for each cylinder of an intake system, and gives a supercharging action by an intake pulsation effect due to its opening / closing operation to increase the charging efficiency of the engine. The present invention relates to an intake control device for an internal combustion engine.

  In an internal combustion engine, by appropriately setting the passage length (intake pipe length) of the intake passage for each cylinder between the surge tank disposed upstream of the intake system and each cylinder, pressure pulsation in the intake passage It is known that the charging efficiency of the engine can be increased. However, this supercharging effect is limited to the vicinity of the engine speed that synchronizes so that the pressure pulsation in the intake passage becomes positive at the closing timing of the intake valve. In order to obtain the effect of improving the charging efficiency in a wider range of operation, it is necessary to change the intake pipe length. For example, two types of intake passages with different lengths are prepared for each cylinder, depending on the engine operating conditions such as high speed or low speed. Techniques for selectively using these are known.

  Separately, an intake control valve that can shut off the intake passage is provided in the intake passage between the intake valve and surge tank of each cylinder, and the intake control valve is controlled to open and close at an appropriate timing during the intake stroke. A technique for generating pressure pulsation in the intake passage for each cylinder to improve the charging efficiency of the engine is disclosed in, for example, Patent Document 1 and the like. In this type of intake control device, it is possible to increase the charging efficiency under a wide range of operating conditions by appropriately controlling the opening and closing timing of the intake control valve in accordance with the operating state of the engine.

The operating principle and effects are outlined. Especially when the engine speed is low, the intake control valve is closed in the first half of the intake stroke to create a negative pressure in the cylinder and in the intake passage, and the intake control valve at the end of the intake stroke. Open the valve. Then, the negative pressure wave travels upstream in the intake passage and is reflected as a positive pressure in the surge tank. If the intake control valve is closed again when the reflected wave returns to the vicinity of the intake valve, the positive pressure is maintained in the intake passage. Therefore, the supercharging action is performed on the cylinders communicating with each other via the intake valve in the valve open state. In addition, even after the intake valve is closed, the closed state of the intake control valve is continued to maintain a positive pressure in the intake passage, thereby scavenging residual gas in the combustion chamber during the valve overlap period in the next cycle. An effect is acquired and the knocking suppression effect by the fall of mixture gas temperature can also be anticipated.
JP 2000-248946 A

  The operation and effect of the above principle can be sufficiently obtained when the engine is in a steady state, but the supercharging effect, that is, the charging efficiency improvement effect caused by the opening and closing of the intake control valve during the intake stroke is the intake stroke. Is obtained in the cycle itself, and the knocking suppression effect by the residual gas scavenging is characterized in that it is an effect on the next cycle. Therefore, when the engine is in a transient state and supercharging is started by opening / closing the intake control valve from a control mode in which the intake control valve is not opened / closed, the supercharging effect is immediately effective, whereas the residual gas scavenging is effective. There will be a delay of one cycle before the effect becomes effective.

  For example, as a control mode of the intake control valve, when the engine is in a high load state, a charging efficiency improvement mode is executed to increase the charging efficiency by opening and closing control of the intake control valve and to promote scavenging of residual gas. When in the low load state, the supercharging effect is unnecessary, so the intake control valve is always fixed in the open state, and when the normally open mode in which the residual gas is also used as the internal EGR is executed, during acceleration, When the engine operating state shifts from the normally open mode in which the intake control valve is not opened and closed to the charging efficiency improvement mode for increasing the charging efficiency, paying attention to the first cycle, the charging efficiency of the engine is Although enhanced, the scavenging effect of the residual gas cannot be obtained in the cycle. Therefore, for this cycle, the temperature of the air-fuel mixture becomes high, and a high load and high temperature state occurs. As a result, there is a concern about the occurrence of temporary knocking, which may cause an unpleasant hitting sound and affect the durability of the engine.

  In the present invention, when the control mode of the intake control valve is changed according to the change in the operating state of the engine as described above, the transient scavenging effect due to the fact that the scavenging effect of the residual gas cannot be obtained in the immediately following cycle. The purpose is to avoid the occurrence of knocking.

  An intake control device for an internal combustion engine according to the present invention has an intake control valve capable of blocking the intake passage in an intake passage for each cylinder upstream of the intake valve, and the intake control valve of the intake control valve according to the operating state of the internal combustion engine. Intake control valve control means for controlling the operation state by switching to a plurality of control modes is provided, and the control mode has at least a charging efficiency improvement mode and a non-supercharging mode.

  In the charging efficiency improvement mode, the intake control valve is opened and closed during the intake stroke to increase the pressure in the intake passage to the target boost pressure at the intake valve closing timing, and the intake passage remains positive even after the intake valve is closed. The opening / closing timing of the intake control valve is controlled so as to be held at the same time.

  That is, the intake control valve is closed halfway through the intake stroke, and negative pressure develops as the piston descends. When the intake control valve opens at a predetermined opening timing during the intake stroke, the negative pressure wave advances upstream and is reflected as positive pressure at the surge tank, so the pressure in the intake passage near the intake valve increases. Sometimes a supercharging effect is obtained by closing the intake control valve. Further, even after the intake control valve is closed, the pressure in the intake passage is maintained at a positive pressure, so that a scavenging effect of residual gas can be obtained in the valve overlap period of the next cycle.

Particularly in the present invention, in the first cycle of each cylinder when the non-supercharging mode is switched to the charging efficiency improvement mode, the opening / closing timing of the intake control valve is the same as the intake passage pressure at the intake valve closing timing. to so that is suppressed lower than the target supercharging pressure, and so the intake passage pressure after the intake valve is closed is higher than the intake passage pressure after the intake valve is closed before the mode switching is controlled . Thereby, the supercharging action in the first cycle is suppressed, and the scavenging action for the next cycle is sufficiently obtained. Therefore, the occurrence of transient knocking immediately after switching is avoided.

  According to the second aspect of the present invention, for the first cycle of each cylinder when the non-supercharging mode is switched to the charging efficiency improvement mode, the ignition timing is the normal ignition timing in the charging efficiency improvement mode. Is more retarded. Thereby, the occurrence of knocking in the first cycle is easily avoided.

  According to the present invention, when the supercharging is started by switching from the non-supercharging mode to the charging efficiency improving mode at the time of transition and the intake control valve is opened and closed, it is caused by the delay of one cycle of the scavenging action of the residual gas. The occurrence of transient knocking can be reliably avoided.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment in which the present invention is applied to an intake control device of a four-cycle gasoline engine as an internal combustion engine. In this internal combustion engine, an intake passage 7 and an exhaust passage 8 are connected to a combustion chamber 3 defined by a piston 2 sliding in a cylinder 1, and an opening end of the intake passage 7 on the combustion chamber 3 side is connected. The intake valve 5 composed of a poppet valve opens and closes, and the exhaust valve 6 composed of a poppet valve opens and closes the opening end of the exhaust passage 8 on the combustion chamber 3 side. The intake valve 5 and the exhaust valve 6 are respectively opened and closed by camshafts (not shown) that rotate in synchronization with the rotation of the crankshaft 4, and are thus opened and closed in synchronization with the rotation of the crankshaft 4. These opening / closing timings are not particularly different from those of a general four-cycle gasoline engine, and the intake valve 5 opens slightly before the intake top dead center and closes slightly after the intake bottom dead center. A spark plug 9 is disposed at the center of the combustion chamber 3. A crank angle sensor 14 for detecting the crank angle of the crankshaft 4 is provided.

  An intake control valve 17 that can shut off the intake passage 7 is provided on the upstream side of the intake valve 5 of the intake passage 7 provided for each cylinder in order to obtain a supercharging effect. The intake control valve 17 can be opened and closed with good responsiveness at any time in one cycle by the intake control valve driving device 17a. For example, the intake control valve 17 includes a flap valve or a butterfly valve type valve that is opened and closed by an electromagnet. Yes. The intake control valve 17 is provided in each intake passage 7 independent for each cylinder, and the position of the intake control valve 17 is determined so that the intake pipe length provides the inertia supercharging effect. It is set to be optimal.

  The intake passage 7 independent for each cylinder is connected to a surge tank 16 common to each cylinder on the upstream side of the intake control valve 17. At the intake inlet of the surge tank 16, a butterfly valve type throttle valve 18 capable of arbitrarily adjusting the intake passage area is disposed. The throttle valve 18 is a so-called electronically controlled throttle valve whose opening degree is controlled by a throttle valve driving device 18a such as a motor.

  In addition, a fuel injection valve 10 is disposed in the intake passage 7 for each cylinder, and an amount of fuel corresponding to a load, that is, an intake air amount, is injected. The fuel injection valve 10 is located in the passage portion 7 a on the downstream side of the intake control valve 12 and is disposed to face the intake valve 5.

  The engine control unit (ECU) 11 controls the opening / closing of the intake control valve 17, the opening degree of the throttle valve 18, the fuel injection amount from the fuel injection valve 10, the ignition timing of the spark plug 9, and the like. . The engine control unit 11 receives a detection signal from the crank angle sensor 14, a detection signal from the water temperature sensor 13, a detection signal from the knock sensor 15 that detects vibration of the cylinder block due to knocking, and the like, and is operated by the driver. An accelerator opening signal is input from an accelerator pedal sensor 12 provided in the accelerator pedal.

  FIG. 2 shows a control map for switching the control mode of the intake control valve 17. The control mode of the intake control valve 17 is basically switched based on the engine rotational speed Ne and the load Te, and the charging efficiency is improved mainly in the high load range of the engine low / medium speed. Opening / closing control is performed during one cycle as the target filling efficiency improvement mode. In addition, since it is possible to obtain the effect of improving the charging efficiency due to the intake pulsation without using the intake control valve 17 in the engine high speed range, and since it is not necessary to improve the charging efficiency at a low load, the intake control valve 17 is The normally open mode is set, and the intake control valve 17 is always kept open. Therefore, for example, when acceleration is performed from point A to point B in the figure, the control mode of the intake control valve 17 shifts from the normally open mode to the charging efficiency improvement mode.

  First, with reference to FIG. 3, the opening / closing timing of the intake control valve 17 and the time transition of the intake pressure when the control mode of the intake control valve 17 is the charging efficiency improvement mode will be described. FIG. 3 shows the case where the internal combustion engine is in steady operation within the region of the charging efficiency improvement mode. In this charging efficiency improvement mode, the intake control valve 17 is opened and closed once during the intake stroke as shown in the figure during each cycle. The “intake port pressure” in the figure indicates the pressure in the intake passage 7 (passage portion 7a) between the intake control valve 17 and the intake valve 5 (more precisely, the pressure immediately before the intake valve 5), and the time transition thereof. When the cylinder is in the compression-combustion-expansion stroke, both the intake control valve 17 and the intake valve 5 are closed, and the passage portion 7a of the intake passage 7 is in the positive position due to the previous cycle. Pressure is maintained. Although this positive pressure may gradually decrease due to a temperature drop due to heat transfer to the wall surface of the intake port or a small amount of leakage from the intake control valve 17, it is maintained until the valve overlap time. When the intake valve 5 is opened at a predetermined intake valve opening timing (IVO), the burned gas remaining in the combustion chamber 3 is passed through the exhaust valve 6 to the exhaust passage 8 due to the pressure held in the passage portion 7a. The residual gas is scavenged. Thereafter, an intake stroke is entered, and negative pressure develops in the passage portion 7a downstream of the intake control valve 17 as the piston 2 descends. When the intake control valve 17 is opened at the intake control valve opening timing (ICVO), the negative pressure generated in the passage portion 7a and the cylinder 1 becomes a pressure wave and propagates upstream through the intake passage 7. The negative pressure wave is reflected as a positive pressure by the surge tank 16 and returns to the passage portion 7a and the cylinder 1 again. If the intake control valve 17 is closed at the timing when the positive pressure wave returns to the passage portion 7a (intake control valve closing timing (ICVC)), a large amount of fresh air can be filled in the cylinder 1 by this positive pressure. A supercharging effect is obtained.

  If the intake control valve 17 is not closed as it is, the pressure oscillation is repeated as shown by the dotted line in the figure.

  The intake valve 5 is closed at a predetermined intake valve closing timing (IVC). Even after the intake valve 5 is closed, the positive pressure P1 can be maintained in the passage portion 7a as shown in the figure by maintaining the intake control valve 17 in the closed state. Generates the effect of scavenging gas.

  The opening timing ICVO and the closing timing ICVC of the intake control valve 17 in the steady state differ depending on the operating state of the engine because the optimum timing for increasing the charging efficiency varies. For example, the table is stored in advance in the engine control unit 11 as a table for the engine speed. By letting it go, it can always be optimally controlled. Note that it is not always necessary to perform control so that the supercharging pressure always becomes maximum, and it is possible to set it at an appropriate timing so as to follow the target supercharging pressure.

  Incidentally, as described above, the supercharging effect due to the opening / closing operation of the intake control valve 17 is immediately obtained in the cycle itself in which the intake control valve 17 is operated, whereas in the passage portion 7a after the intake control valve closing timing ICVC. The effect of scavenging the residual gas while maintaining the positive pressure P1 is only an effect on the next cycle. Therefore, when the control mode of the intake control valve 17 shifts from the normally open mode to the charging efficiency improving mode as in the acceleration from the point A to the point B shown in FIG. 2, the first cycle immediately after the mode switching. In the (first cycle of each cylinder), although the charging efficiency is improved by the supercharging effect, the scavenging effect of the residual gas cannot be obtained, and knocking occurs temporarily due to the increase in the load and the rise in the mixture temperature. There are concerns.

  4 and 5 show a first embodiment of the control performed for the first cycle of each cylinder immediately after switching the control mode in order to cope with such a problem.

  FIG. 4 shows the time variation of the intake control valve 17 opening / closing timing and the intake pressure as in FIG. 3. In particular, the first time after the control mode is switched from the normally open mode to the charging efficiency improving mode. The behavior of the cycle is shown. Although the timing for switching the control mode is not shown in the figure, the intake control valve 17 is closed along with the switching of the control mode, and the intake control valve 17 is at least before the opening timing IVO of the intake valve 5. Closed. At this time, the pressure P0 of the passage portion 7a is almost atmospheric pressure.

  In the first embodiment, as shown in the drawing, the opening timing ICVO and the closing timing ICVC of the intake control valve 17 in the first cycle are compared with the normal opening / closing timing in the charging efficiency improvement mode shown in FIG. The closing timing ICVC has a slightly retarded characteristic. However, the intake control valve closing timing ICVC is not delayed from the intake valve closing timing IVC. In other words, in the steady state, the closing timing ICVC of the intake control valve 17 is set so as to be closed when the pressure vibration reaches the maximum pressure as shown in FIG. 3, for example, in order to increase the supercharging effect. However, in the first cycle at the time of switching, the closing timing ICVC of the intake control valve 17 is slightly delayed from the setting at the steady state, so that the pressure at the intake control valve closing timing ICVC is changed from the steady state. Also keep it low. Along with this, the pressure at the intake valve closing timing IVC, that is, the supercharging pressure in the cylinder 1, becomes lower than the supercharging pressure that is the target at the time of steady state, and the increase in load is suppressed, so that the occurrence of knocking is avoided. Can do.

  On the other hand, although the boost pressure is lower than that in the steady state, the supercharging pressure is maintained in the intake passage 7 (passage portion 7a) even after the intake valve 5 is closed. As in the case of, the scavenging effect of the residual gas is obtained during the valve overlap period, and the mixture temperature is suppressed. Therefore, since the knocking suppression effect by scavenging can be obtained from the next cycle, it is possible to sufficiently perform supercharging making the most of the effect of the intake control valve 17. That is, the intake control valve is set so that the pressure P1 in the passage portion 7a after the intake valve 5 is closed in the first cycle is higher than the pressure P0 in the passage portion 7a after the intake valve 5 is closed before mode switching. The closing timing ICVC is controlled.

  A method of adding a predetermined value to the intake control valve closing timing ICVC in a steady state is simple for the retard amount of the intake control valve closing timing ICVC. However, the retardation amount corresponding to the engine rotation speed is referred to as a table. Alternatively, the delayed closing timing for the first cycle may be held as a table, and only the first cycle may be referred to as the closing timing ICVC.

  FIG. 5 is a flowchart showing the control flow of the first embodiment. The control routine of FIG. 5 is started from step S01. First, signals from various sensors are read in step S02, and the operation state of the engine is comprehensively determined based on these information in step S03. In step 04, the control mode of the intake control valve 17 is determined based on, for example, the control map of FIG. In step S05, if the control mode is the normally open mode, the process proceeds to step S16, and the setting for normally opening the intake control valve 17 is performed.

  When the control mode is the charging efficiency improvement mode in step S17, the process proceeds to step S06, and the opening timing ICVO and the closing timing ICVC of the intake control valve 17 are read from the table for the engine speed. In step S07, it is determined whether or not the control mode of the intake control valve 17 is the first cycle of each cylinder after shifting to the charging efficiency improvement mode. If it is determined that the cycle is the first cycle, the process proceeds to step S08. The delay angle correction is performed on the closing timing ICVC at the normal time set in step S06. In step S20, the intake control valve 17 is actually driven and controlled based on the value set as described above. Therefore, in the first cycle after the mode switching to the charging efficiency improvement mode, the intake control valve 17 is opened and closed at the timing illustrated in FIG. 4, and in the subsequent cycle of the charging efficiency improvement mode, as illustrated in FIG. The intake control valve 17 is opened and closed at a proper timing. In the normally open mode, the intake control valve 17 is not opened and closed and is always kept open.

  As described above, according to the present embodiment, the closing pressure ICVC of the intake control valve 17 is retarded from the steady state in the first one cycle when the control mode is shifted, so that the boost pressure in the first cycle is reduced. Suppressing to prevent knocking and maintaining a positive pressure in the passage portion 7a to obtain the residual gas scavenging effect of the next cycle. After that, sufficient acceleration torque is obtained with a large supercharging pressure. It is possible to avoid the occurrence of knocking.

  Next, the flowchart of FIG. 6 shows a second embodiment in which the processing of the first embodiment is partially changed. In this embodiment, in order to avoid knocking in the first cycle, the retard of the ignition timing is used together. In step S07, after the transition to the charging efficiency improvement mode, the first of each cylinder is changed. If it is determined that the current cycle is a cycle, the process proceeds to step S08, the delay angle correction is performed on the stationary closing timing ICVC set in step S06, and the ignition timing of the cylinder is determined in step S09. The ignition timing is set later than the ignition timing in the steady state in the charging efficiency improvement mode (in other words, the ignition timing after the second cycle). The ignition timing retardation correction amount may be a fixed amount, a value corresponding to the operating state, or the ignition timing after the retardation correction, similar to the retardation amount of the closing timing ICVC described above. It is good also as the form which allocated itself to the map. Note that the processing of the other steps is not particularly different from that in FIG.

  Thus, according to the second embodiment combined with the ignition timing correction, knocking in the first cycle after the control mode shifts to the charging efficiency improvement mode is reliably avoided. In addition, since knocking in the first cycle is less likely to occur, the suppression margin for the supercharging pressure due to the retard of the intake control valve closing timing ICVC can be set to be small accordingly. For example, the retard amount of the intake control valve closing timing ICVC can be reduced so that the pressure P1 in FIG. 4 becomes higher, and the rising of acceleration can be improved while avoiding knocking. Moreover, the scavenging action of the next cycle is also improved by increasing the pressure P1.

  Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, when the closing timing ICVC of the intake control valve 17 is controlled to be retarded from the normal time in the first cycle when the control mode is switched, the closing timing ICVC is later than the closing timing IVC of the intake valve 5. The corner side is different from the first embodiment.

  As shown in FIG. 7, in the first cycle immediately after the control mode switching, the closing timing ICVC of the intake control valve 17 is delayed by a larger amount than the closing timing ICVC at the normal time (see FIG. 3). It is behind the closing timing IVC. In particular, the intake control is performed so that the pressure P1 in the passage portion 7a at the closing timing ICVC of the intake control valve 17 is higher than the pressure (that is, the supercharging pressure) P2 in the passage portion 7a at the intake valve closing timing IVC. The closing timing ICVC of the valve 17 is controlled.

  Thus, by delaying the closing timing ICVC of the intake control valve 17 from the closing timing IVC of the intake valve 5, the intake valve 7 enters the intake passage 7 after the intake valve closing timing IVC than the supercharging pressure P2 at the intake valve closing timing IVC. The retained pressure P1 can be increased, and the residual gas scavenging effect of the next cycle can be obtained while suppressing the supercharging effect for the first cycle.

  Here, during the opening period of the intake control valve 17, the pressure in the intake passage 7 pulsates as shown in the figure, but the closing timing ICVC of the intake control valve 17 is set to the timing of the second positive pressure wave of the pressure pulsation. Then, the pressure P1 held for scavenging in the next cycle is increased, and the maximum residual gas scavenging effect can be obtained. It is effective to store this intake control valve closing timing ICVC in a table or map corresponding to the engine operating state as described above, but it is also possible to determine the closing timing ICVC by the following simpler method. It is.

  That is, during the valve opening period of the intake control valve 17 in a steady state (ICVO to ICVC period), the negative pressure wave generated by opening the intake control valve 17 is positive in the surge tank 16 in order to maximize the supercharging effect. It is set so as to coincide with the time until it is reflected as a pressure wave and returned to the vicinity of the intake valve 5. Therefore, in the first cycle, if this valve opening period is approximately three times that of the steady state, the positive pressure wave returns to the negative pressure wave and returns to the positive pressure wave again, that is, the second time. The peak of the positive pressure wave is the closing timing ICVC.

  The control flowchart according to the third embodiment is not particularly different from that shown in FIG. In the third embodiment, the closing timing retard amount of the intake control valve 17 in step S08 described above is set in advance in a table so that the retarded closing timing ICVC is later than the closing timing IVC of the intake valve 5. ing. Alternatively, when the closing timing ICVC of the intake control valve 17 is set so that the valve opening period of the intake control valve 17 is three times as long as normal, the opening of the intake control valve 17 that has been set in step S06 is set. The retarded closing timing may be obtained by calculating the valve opening period from the timing / closing timing, multiplying this by 3 and adding it to the valve opening timing again.

  As described above, according to the present embodiment, the closing timing ICVC of the intake control valve 17 is retarded in the first cycle when the control mode is shifted, thereby suppressing the boost pressure P2 and preventing the occurrence of knocking. In addition to preventing the positive pressure P1 held in the passage portion 7a, the effect of scavenging residual gas in the next cycle is increased.

  Next, a fourth embodiment of the present invention will be described. In the third embodiment, when the closing timing ICVC of the intake control valve 17 is controlled to be retarded from the steady state in the first cycle when the control mode is switched, the opening timing ICVO is also retarded at the same time. Different for example. FIG. 8 shows the opening / closing timing of the intake control valve 17 and the pressure history in the passage portion 7a in the fourth embodiment.

  In this embodiment, the opening timing ICVO and the closing timing ICVC of the intake control valve 17 are both retarded by the same retardation amount. Therefore, the valve opening period (ICVO to ICVC period) of the intake control valve 17 is the same as that during normal operation (see FIG. 3), and the intake valve 5 is closed during the valve opening period (ICVO to ICVC). IVC is located. That is, the period until the negative pressure wave returns as a positive pressure wave in the surge tank 16 is substantially constant at the same engine speed, so that the opening timing ICVO is maintained while keeping the valve opening period of the intake control valve 17 constant. By delaying both the closing timing ICVC and the steady timing ICVC, the peak of the first positive pressure wave can be synchronized with the closing timing ICVC. Therefore, while suppressing the supercharging pressure P2 at the closing timing IVC of the intake valve 5 to be low, the pressure P1 held in the passage portion 7a can be maximized, and the residual gas scavenging effect of the next cycle can be most effectively obtained. Become.

  FIG. 9 is a flowchart showing the flow of control according to the fourth embodiment. Since this flowchart is also similar to the flowcharts in the embodiments already described, description of common parts is omitted. In the flowchart of FIG. 5 described above, the closing timing ICVC of the intake control valve 17 set in step S06 is corrected in step S08. However, in the fourth embodiment, the intake control valve 17 is opened. Since both the timing ICVO and the closing timing ICVC are retarded, the opening / closing timing table for the steady state and the opening / closing timing table for the first cycle when the control mode is the charging efficiency improvement mode are separately provided. Is provided. Then, if the opening / closing timing set in step S06 is the first cycle after switching the control mode, it is reset from the opening / closing timing table for retardation correction in step S08.

  As described above, according to the fourth embodiment, the closing timing ICVC of the intake control valve 17 is retarded in the first cycle when the control mode is shifted to suppress the supercharging pressure P2 in the first cycle. Thus, the occurrence of knocking can be prevented, and the pressure P1 of the first positive pressure peak of the pressure pulsation can be held in the intake passage 7, and there is an advantage that the residual gas scavenging effect of the next cycle becomes larger.

  Next, the flowchart of FIG. 10 shows a fifth embodiment of the present invention. In this embodiment, for the first cycle after switching to the charging efficiency improvement mode, the opening / closing timing of the intake control valve 17 is not changed, and the ignition timing is retarded to suppress knocking. is there.

  That is, if it is determined in step S07 that the cycle is the first cycle of each cylinder after shifting to the charging efficiency improvement mode, the process proceeds to step S08, and the ignition timing of the cylinder is determined in the charging efficiency improvement mode. The ignition timing is corrected to be retarded from the normal ignition timing (in other words, the ignition timing after the second cycle). The ignition timing retardation correction amount may be a fixed amount, a value corresponding to the operating state, or the ignition timing after the retardation correction, similar to the retardation amount of the closing timing ICVC described above. It is good also as the form which allocated itself to the map. The processing of other steps is not particularly different from the above-described FIG.

  Thus, according to the present embodiment in which knocking is avoided by retarding the ignition timing, the intake control valve 17 is opened and closed as shown in FIG. Accordingly, the pressure held in the passage portion 7a after the closing timing IVC of the intake valve 5 is very high, and the residual gas scavenging effect for the next cycle is increased. Although the supercharging pressure in the first cycle is high, knocking can be reliably avoided by retarding the ignition timing.

  In each of the above embodiments, as shown in FIG. 2, the control mode of the intake control valve 17 has been described as including the charging efficiency improvement mode and the normally open mode. As a mode, for example, it is possible to provide a mode (pump loss reduction mode) that reduces the pump loss while limiting the substantial intake amount entering the cylinder 1 by opening in the first half of the intake stroke and closing in the middle of the intake stroke. It is. The present invention can be similarly applied when switching from the pump loss reduction mode to the charging efficiency improvement mode.

1 is a system configuration diagram of an internal combustion engine provided with an intake air control device according to the present invention. The characteristic view which shows allocation of the control mode of an intake control valve. The timing chart which shows the opening and closing time etc. of regular time. The timing chart which shows the opening / closing timing etc. of the first cycle in 1st Example. The flowchart which shows the flow of control of 1st Example. The flowchart which shows the flow of control of 2nd Example. The timing chart which shows the opening / closing timing etc. of the first cycle in 3rd Example. The timing chart which shows the opening / closing timing etc. of the first cycle in 4th Example. The flowchart which shows the flow of control of 4th Example. The flowchart which shows the flow of control of 5th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder 2 ... Piston 5 ... Intake valve 7 ... Intake passage 11 ... ECU (engine control unit)
16 ... Surge tank 17 ... Intake control valve

Claims (13)

An intake control valve capable of blocking the intake passage is provided in the intake passage for each cylinder upstream of the intake valve, and the operation state of the intake control valve is switched to a plurality of control modes according to the operating state of the internal combustion engine. In an intake control device for an internal combustion engine provided with an intake control valve control means,
As the control mode, it has at least a charging efficiency improvement mode and a non-supercharging mode,
In the charging efficiency improvement mode, the intake control valve is opened and closed during the intake stroke to increase the pressure in the intake passage to the target boost pressure at the intake valve closing timing, and the intake passage remains positive even after the intake valve is closed. The opening and closing timing of the intake control valve is controlled so as to be held at
In the first cycle of each cylinder when the non-supercharging mode is switched to the charging efficiency improving mode, the opening / closing timing of the intake control valve is the same as the target boost pressure at the intake passage closing timing. to so that is suppressed lower than, and as the intake passage pressure after the intake valve is closed is higher than the intake passage pressure after the intake valve is closed before the mode switching, characterized in that it is controlled An intake control device for an internal combustion engine.   The intake control apparatus for an internal combustion engine according to claim 1, wherein the non-supercharging mode is a normally open mode in which the intake control valve is always maintained in an open state.   2. The intake control device for an internal combustion engine according to claim 1, wherein the non-supercharging mode is a pump loss reduction mode in which the intake control valve is opened in advance and closed in the middle of an intake stroke.   2. The opening / closing timing of the intake control valve in the first cycle has a characteristic that the closing timing of the intake control valve is retarded as compared with a normal opening / closing timing in the charging efficiency improvement mode. The intake control device for an internal combustion engine according to any one of?   5. The intake control apparatus for an internal combustion engine according to claim 4, wherein the closing timing of the intake control valve in the first cycle is retarded from the closing timing of the intake valve.   The closing timing of the intake control valve is controlled such that the pressure in the intake passage at the closing timing of the intake control valve in the first cycle is higher than the pressure in the intake passage at the closing timing of the intake valve. An intake control device for an internal combustion engine according to claim 5.   The closing timing of the intake control valve in the first cycle is controlled at a timing when the pressure in the intake passage becomes the first maximum value after the closing timing of the intake valve. An intake control device for an internal combustion engine.   The closing timing of the intake control valve in the first cycle is controlled so that the opening period of the intake control valve is approximately three times the opening period of the normal opening / closing timing in the charging efficiency improvement mode. An intake control device for an internal combustion engine according to any one of claims 4 to 7.   Along with the delay of the closing timing of the intake control valve in the first cycle, the opening timing of the intake control valve is delayed from the normal opening timing in the charging efficiency improvement mode. Item 8. The intake control device for an internal combustion engine according to any one of Items 4 to 7.   10. The intake control apparatus for an internal combustion engine according to claim 1, wherein, in the first cycle, the ignition timing is corrected to be retarded from the normal ignition timing in the charging efficiency improvement mode. . An intake control valve capable of blocking the intake passage is provided in the intake passage for each cylinder upstream of the intake valve, and the operation state of the intake control valve is switched to a plurality of control modes according to the operating state of the internal combustion engine.
An intake control device for an internal combustion engine comprising an intake control valve control means for controlling
As the control mode, it has at least a charging efficiency improvement mode and a non-supercharging mode,
In the charging efficiency improvement mode, the intake control valve is opened and closed during the intake stroke to increase the pressure in the intake passage to the target boost pressure at the intake valve closing timing, and the intake passage remains positive even after the intake valve is closed. The opening and closing timing of the intake control valve is controlled so as to be held at
In the first cycle of each cylinder when the non-supercharging mode is switched to the charging efficiency improvement mode, the ignition timing is retarded from the normal ignition timing in the charging efficiency improvement mode. An intake control device for an internal combustion engine.   The intake control apparatus for an internal combustion engine according to claim 11, wherein the non-supercharging mode is a normally open mode in which the intake control valve is always maintained in an open state. 12. The intake control device for an internal combustion engine according to claim 11, wherein the non-supercharging mode is a pump loss reduction mode in which the intake control valve is opened in advance and closed in the middle of an intake stroke.

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