JP2010209777A - Air quantity control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air quantity control device for an internal combustion engine for suitably continuing the travel of a vehicle by securing the quantity of intake air into the engine even if a failure occurs in a variable valve train. <P>SOLUTION: The air quantity control device includes the intake-valve variable valve trains and the exhaust-valve variable valve trains provided in a plurality of cylinder groups of the internal combustion engine 1 for varying the valve lift amount of intake valves 4 and for varying valve timing for exhaust valves 8, respectively, a secondary air supply device 22 for supplying secondary air to downstream sides of the exhaust valves 8 of the internal combustion engine 1, and a means for determining such a failure state that the operating angles of the intake-valve variable valve trains are smaller than specified values. When a failure occurs in the intake-valve variable valve train in any cylinder group, the secondary air supply device 22 is operated over a range from an exhaust stroke to an intake stroke and valve timing for the exhaust valve 8 in the cylinder group is controlled to be retarded by the exhaust-valve variable valve train in the cylinder group so that the valve closing timing is retarded to a top dead center or later. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an air amount control device for an internal combustion engine provided with a variable valve mechanism that makes the valve lift amount of an intake valve variable, and more particularly, to an internal combustion engine suitable for fail-safe traveling when the variable valve mechanism fails. The present invention relates to an air amount control device.

  Conventionally, a variable valve mechanism that makes the valve lift amount of the intake valve variable is provided, and even if the variable valve mechanism breaks down on the low lift side of the intake valve, try to secure the intake air amount required for engine operation An air amount control device for an internal combustion engine is proposed (see Patent Document 1).

  When the failure of the variable valve mechanism that makes the valve lift amount of the intake valve variable is determined, the drive of the variable valve mechanism is stopped. When the engine rotational speed exceeds a predetermined value and the suction negative pressure is smaller than the predetermined value, the throttle valve opening upper limit value is set, and the throttle valve is controlled below the opening upper limit value to control the engine The amount of intake air is controlled.

JP-A-2005-214167

  However, in the above conventional example, in the state where the valve lift amount of the intake valve is secured more than a predetermined lift amount due to the failure of the variable valve mechanism, the intake air amount of the engine is secured by opening the throttle valve and the vehicle continues to travel. Although it is possible, when the intake valve is repeatedly opened and closed, the control shaft is urged in the small lift direction, the valve lift amount gradually decreases, and is returned to the stopper position that regulates the minimum lift amount. There was a problem that the amount could not be secured and the vehicle could not be continued.

  Therefore, the present invention has been made in view of the above problems, and an air amount control device for an internal combustion engine suitable for ensuring the intake air amount of an engine and continuing vehicle travel even when a variable valve mechanism fails. The purpose is to provide.

  The present invention includes a variable valve mechanism for an intake valve that makes the valve lift amount of the intake valve variable in the internal combustion engine, and a variable valve mechanism for the exhaust valve that makes the valve timing of the exhaust valve variable. A secondary air supply device that supplies secondary air downstream of each exhaust valve for exhaust purification by a catalyst disposed in the exhaust passage, and means for determining a failure state of the variable valve mechanism for the intake valve. And when the failure state determination means determines that the intake valve variable valve mechanism has failed, the secondary air supply device is operated in an exhaust stroke or an intake stroke, and the exhaust valve variable valve is operated. The valve timing of the exhaust valve is retarded by the mechanism, and the valve closing timing is retarded after top dead center.

  Therefore, in the present invention, when it is determined by the failure state determination means that the variable valve mechanism for the intake valve has failed, the secondary air supply device is operated in the exhaust stroke or the intake stroke, and the exhaust valve Since the valve timing of the exhaust valve is retarded by the variable valve mechanism so that the closing timing is retarded after top dead center, the secondary air injected downstream of the exhaust valve is exhausted during the intake stroke. Even when passing through the valve, the vehicle can be made to fail by being introduced into the combustion chamber.

1 is a schematic system configuration diagram to which an air amount control device for an internal combustion engine showing an embodiment of the present invention is applied. The schematic system block diagram to which the air quantity control apparatus of the internal combustion engine similarly containing an exhaust system is applied. The block diagram of a secondary air supply apparatus. The conceptual diagram which shows the variable valve mechanism of an intake valve. Explanatory drawing explaining the operating state of a variable valve mechanism. The conceptual diagram explaining the variable valve mechanism of an exhaust valve. The block diagram of a control system. The flowchart of the fail safe control at the time of failure of the variable valve mechanism of an intake valve. Failure control subroutine executed during fail-safe control. Sub-bank fault control subroutine executed during fail-safe control. Sub-bank fault control subroutine executed during fail-safe control. Explanatory drawing explaining the change of the opening / closing timing and lift amount of an exhaust valve and an intake valve at the time of failure of the VEL apparatus of one bank. Explanatory drawing explaining the change of the opening / closing timing and lift amount of an exhaust valve and an intake valve at the time of failure of the VEL apparatus of both banks.

Hereinafter, an air amount control device for an internal combustion engine of the present invention will be described based on each embodiment.
FIG. 1 is a configuration diagram showing a first embodiment of an air amount control device for an internal combustion engine to which the present invention is applied.

  In FIG. 1, an electric throttle valve 3 whose opening degree is controlled by an engine control unit (hereinafter referred to as ECM) 10 is installed in an intake passage 2 upstream of the V-type internal combustion engine 1. The air controlled by the electric throttle valve 3 is branched and introduced into the intake manifolds 2A and 2B connected to the left and right banks 1A and 1B, and is introduced into the combustion chamber 5 via the intake valves 4 of the respective cylinders. Inhaled.

  The intake valve 4 of each cylinder has a valve operation angle (open period) of the intake valve 4, more specifically, a valve operation angle and lift amount variable device (VEL device) capable of continuously changing the valve operation angle and the lift amount; VEL actuators 49R, 49L) and a valve timing variable device (VTC device; VTC actuators 51R, 51L) capable of continuously changing the valve timing (center phase of the valve operating angle) of the intake valve 4 It is driven by a variable valve device.

  The combustion chamber 5 is provided with a spark plug 6 and a fuel injection valve 7 (not shown). The fuel injection valve 7 is energized to the solenoid by an injection pulse signal output in the intake stroke or the compression stroke in synchronization with the engine rotation from the ECM 10, and is adjusted to a predetermined pressure in the combustion chamber 5. Inject fuel.

  The fuel injected into the combustion chamber 5 forms an air-fuel mixture with the air introduced into the combustion chamber 5 and is ignited and burned by the spark plug 6 at the ignition timing determined by the ECM 10. The exhaust gas after combustion is discharged to the exhaust passage 9 through the exhaust valve 8, and as shown in FIG. 2, the upstream catalyst 13R, 13L, the three-way catalyst 14R, 14L, and the downstream catalyst 15R having the HC trap function. After being purified by 15L, it is released into the atmosphere through a muffler (not shown).

  In order to promote the exhaust purification function of the upstream catalyst 13R, 13L, the three way catalyst 14R, 14L and the downstream catalyst 15R, 15L having the HC trap function, the exhaust manifold 9A downstream of the exhaust valve 8 which is the outlet of the combustion chamber 5 Secondary air injection nozzles 21 for supplying secondary air are disposed at the respective inlets. Secondary air is supplied to the secondary air injection nozzle 21 from a secondary air injection device 22 described later.

  Further, an air-fuel ratio sensor 23 (A / F sensor) is provided in the exhaust passage 9 between the preceding catalysts 13R, 13L and the three-way catalysts 14R, 14L, and the three-way catalysts 14R, 14L and the downstream catalyst 15R, An oxygen sensor 24 (O2 sensor) is provided in the exhaust passage 9 between 15 L, and these signals are input to the ECM 10 and air-fuel ratio feedback control for optimally controlling the amount of fuel supplied from the fuel injection valve 7. Is implemented.

  As shown in FIG. 3, the secondary air supply device 22 introduces outside air through the sub air cleaner 31, the introduction passage 32, the air pump 33, the supply conduit 34, and the supply valves 35R and 35L of the left and right banks. The secondary air injection nozzle 21 is supplied to the secondary air injection nozzle 21 and injected from the secondary air injection nozzle 21 to the inlet of the exhaust manifold 9A of each cylinder. The air pump 33 is ON / OFF controlled by the power supplied from the power supply 25 via the fuse by the ON operation of the pump relay 26 controlled to be opened and closed by the ECM 10. The supply valves 35R and 35L are ON / OFF controlled by the power supplied from the power supply 25 through the fuses by the ON operation of the valve relay 27 that is controlled to be opened and closed by the ECM 10. An air flow meter 36 for measuring the amount of air introduced is arranged downstream of the sub air cleaner 31 and configured to input the detected air amount signal to the ECM 10.

  Returning to FIG. 1, the exhaust valve 8 is driven to open and close while maintaining a constant valve lift by a cam provided on the exhaust side camshaft 8A for each bank. And the variable valve apparatus which consists of a valve timing variable apparatus (VTC apparatus; VTC actuator 8B) which can change continuously the valve timing (center phase of valve | bulb operating angle) of the exhaust valve 8 is provided.

  The ECM 10 includes signals as engine operating conditions such as an accelerator opening APO detected by the accelerator pedal sensor 11, an engine speed Ne detected by the crank angle sensor 12, and an intake air amount Qa detected by the air flow meter 13. Is entered.

  The variable valve operating device of the intake valve 4 is configured as shown in FIG. 4 for each bank. In the illustrated example, only one (for example, the right bank) of the variable valve operating apparatus is illustrated, and the other (for example, the left bank) is simply described in a block format. ing. Here, only one bank (for example, the right bank) will be described.

  Above the valve lifter 40 at the end of the intake valve 4 (two are provided per cylinder), a camshaft 41 that is driven to rotate around the shaft in conjunction with a crankshaft (not shown) extends in the cylinder row direction. is doing. A swing cam 42 is swingably mounted on the outer periphery of the cam shaft 41 corresponding to the intake valve 4, and the swing cam 42 abuts against and presses the valve lifter 40. The valve 4 is driven to open and close against the spring force of a valve spring (not shown).

  Between the cam shaft 41 and the swing cam 42, the posture of the link that mechanically links both 41 and 42 is changed so that the valve operating angle (open period) and the lift amount of the intake valve 4 are continuously increased. Are provided with a variable valve operating angle and lift variable device (VEL device).

  The VEL device includes a drive cam 43 that is eccentrically provided on the cam shaft 41 and rotates integrally with the cam shaft 41, a ring-shaped link 44 that is fitted on the outer periphery of the drive cam 43 so as to be relatively rotatable, and a cam shaft. 41, a control shaft 45 extending substantially parallel to the cylinder row direction, a control cam 46 that is eccentrically provided on the control shaft 45 and rotates integrally with the control shaft 45, and a relative rotation around the outer periphery of the control cam 46 The rocker arm 47 has one end connected to the tip of the ring-shaped link 44 and is rotatably connected to the other end of the rocker arm 47 and the tip of the swing cam 42. , 42 are coupled to each other mechanically.

  The cam shaft 41 and the control shaft 45 are rotatably supported on the cylinder head side of the engine 1 via a bearing bracket. One end of the control shaft 45 is connected to the output end of an actuator (VEL actuator) 49 for changing the valve operating angle and lift amount. The control shaft 45 is driven to rotate around the axis within a predetermined control angle range by the VEL actuator 49. And maintained at a predetermined rotational phase.

  With the above configuration, when the camshaft 41 rotates in conjunction with the crankshaft, the ring-shaped link 44 is operated to reciprocate in the direction orthogonal to the camshaft 41 via the drive cam 43, thereby controlling the rocker arm 47. The intake valve 4 is driven to open and close by swinging around the cam 46 and swinging the swing cam 42 via the rod-shaped link 48.

  Further, by changing the rotation position of the control shaft 45 by the VEL actuator 49, the center position of the control cam 46 which is the rocking center of the rocker arm 47 is changed, and the postures of the links 44, 48, etc. are changed. The swing angle range of the swing cam 42 changes. As a result, the valve operating angle and the lift amount continuously change while the central phase of the valve operating angle remains substantially constant. For example, when the control shaft 45 is rotated in one direction, the valve operating angle and the lift amount are increased, and when the control shaft 45 is rotated in the other direction, the valve operating angle and the lift amount are decreased. If the valve operating angle is determined, the valve lift amount is uniquely determined.

  Therefore, by duty-controlling the energization amount of the VEL actuator 49, the rotational position of the control shaft 45 can be changed to change the valve operating angle and the lift amount of the intake valve 4 (see A in FIG. 5). Thus, a valve operating angle and lift amount variable device (VEL device) is configured.

  On the other hand, the camshaft 41 is driven by the rotation of the crankshaft being input to the sprocket 50 by the timing belt, and the rotational phase of the camshaft 41 is controlled between the sprocket 50 and the camshaft 41 to change the valve timing. A possible rotary actuator (VTC actuator) 51 is mounted.

  Therefore, by duty-controlling the energization amount of the VTC actuator 51, the rotational phase between the crankshaft and the camshaft 41 can be changed, and the valve timing (center phase of the valve operating angle) of the intake valve 4 can be changed. (Refer to A in FIG. 5), thereby, a variable valve timing device (VTC device) is configured.

  Further, as shown in FIG. 6, the VTC device of the variable valve system provided in each bank is similar to the VTC device of the intake valve 4 in that the exhaust camshaft 8A has the crankshaft rotating to the sprocket 52 by the timing belt. Although it is inputted and driven, a rotary actuator (VTC actuator) 8B capable of controlling these rotational phases is mounted between the sprocket 52 and the camshaft 8A in order to change the valve timing.

  Therefore, duty control of the energization amount of the VTC actuator 8B can change the rotation phase between the crankshaft and the camshaft 8A and change the valve timing of the exhaust valve 8 (the center phase of the valve operating angle). Thus, a variable valve timing device (VTC device) is configured.

  The VTC actuators 51R, 51L, 8BR, and 8BL of the VTC device of the left and right banks of the intake valve 4 and the exhaust valve 8 are controlled by the ECM 10 that is the first control unit, as shown in FIG. The VEL actuators 49R and 49L of the VEL device of the intake valves 4 in the left and right banks are controlled by second control units (hereinafter referred to as VEL-C / U) 20R and 20L different from the ECM 10 that is the first control unit.

  For each control described above, the ECM 10 receives signals from the VTC position sensors 51RS, 51LS, 8CR, and 8CL that detect the actual positions of the VTC actuators 51R and 51L, and detects the VTC actual value (actual valve timing). The VEL-C / U 20R, 20L receives the signals of the VEL position sensors 49RS, 49LS that detect the actual positions of the VEL actuators 49R, 49L, and detects the actual VEL value (actual valve operating angle). It has a function.

  However, the function for calculating the VEL target value (target valve operating angle) according to the engine operating condition and the function for calculating the VTC target value (target valve timing) according to the engine operating condition include various sensors relating to the engine operating condition. Are concentrated on the ECM 10 to which the signals are input.

  The ECM 10 and the VEL-C / U 20R, 20L are connected by a communication means (CAN) 30 so that the VEL target value (target valve operating angle) is transmitted from the ECM 10 to the VEL-C / U 20R, 20L. The CAN (Controller Area Network) enables data transmission / reception between control units by connecting the control units with a communication line and performing serial communication.

  Further, the VEL actual value (actual valve operating angle) is transmitted from the VEL-C / U 20R, 20L to the ECM 10. This is because the actual valve operating angle is used for calculating the intake air amount in the ECM 10.

  Next, in the V-type internal combustion engine 1 provided with two VEL devices as the intake air amount control system for each bank (cylinder group), the fail-safe control at the time of failure of the intake air amount control system according to the present invention will be described. .

  Specifically, the presence or absence of a failure in the VEL device is diagnosed. If at least one of the VEL devices fails, the secondary air supply device 22 is operated from the exhaust stroke to the intake stroke, and the exhaust of the failed bank is detected. The valve timing of the VTC device of the valve 8 is retarded. As a result, the secondary air supplied from the secondary air supply device 22 is introduced into the combustion chamber 5 via the exhaust valve 8 of the failure side bank, and the fail safe control is performed to compensate the intake air amount control of the failure side bank. . The failsafe control will be described with reference to the flowcharts of FIGS.

  In step S1, failure diagnosis is performed on the VEL devices in the left and right banks, and the process proceeds to step S2. In this fault diagnosis, the outputs of the VEL position sensors 49RS and 49LS in the left and right banks are monitored, and the VEL actual value does not change when the VEL actual value does not change after a predetermined time with respect to the VEL target value of the ECM 10. It is determined that there is a failure on the side. In this determination, for example, when the VEL actuators 49R and 49L fail, only the VEL device in one bank is in a state of failure. However, for example, in the case of a failure in the power supply system to the VEL actuators 49R and 49L, the VEL devices in both banks are in a state of failure.

  In step S2, it is determined from the diagnosis result in step S1 whether or not the VEL devices in the left and right banks are normal. If both the VEL devices in both banks are normal, the process proceeds to step S3, and the normal control is continued and processed. Exit. However, if the VEL device in either bank is faulty, the process proceeds to step S4, VEL fault control is executed, and then the process proceeds to step S5.

  As shown in FIG. 9, the VEL failure control in step S4 operates the secondary air supply device 22 from the exhaust stroke to the intake stroke in step S8, and in step S9 the VTC device of the exhaust valve 8 on the failure bank side. The valve timing is delayed.

  As a result, when the VEL device in one bank fails, the secondary air injected from the secondary air injection nozzle 21 immediately downstream of the exhaust valve 8 flows toward the downstream of the exhaust passage 9 in the exhaust stroke. However, since the failed bank-side exhaust valve 8 is opened by retarding control at the stage of shifting to the intake stroke, it is introduced into the combustion chamber 5 from the exhaust manifold 9A via the exhaust valve 8. The In this case, since the normal bank-side VEL device is operating normally, the air introduced into the intake manifolds 2 </ b> A and 2 </ b> B is introduced into the combustion chamber 5 via the intake valve 4. When the VEL devices in both banks fail, the secondary air injected immediately downstream of the exhaust valve 8 from the secondary air injection nozzle 21 flows downstream of the exhaust passage 9 in the exhaust stroke. At the stage of shifting to the intake stroke, the exhaust valves 8 on both banks are opened by being retarded, so both banks are introduced into the combustion chamber 5 from the exhaust manifold 9A via the exhaust valves 8. Is done.

  In step S5, it is determined from the diagnosis result in step S1 whether or not the remaining bank-side VEL devices are normal. If the VEL device in one bank is normal, the process proceeds to step S6. Start control. If the determination in step S5 is a failure of the VEL devices in both banks, the process proceeds to step S7, and both bank failure control is started in step S7.

  The one-bank failure control is executed by the ECM 10 as shown in FIG.

  First, in step S21, the amount of air introduced per cylinder in the failed bank is calculated. The amount of introduced air in this case is proportional to the product of the valve opening period and the lift amount in the intake stroke of the exhaust valve 8, that is, the valve opening area amount in the intake stroke of the exhaust valve 8, so this valve opening area amount. Is calculated.

  In step S22, the VEL target value of the VEL device in the normal bank that is equivalent to the valve opening area amount in the intake stroke of the exhaust valve 8 in step S21 is calculated, and the VEL-C / U20R or 20L in the normal bank is calculated. Output to.

  In step S23, the ignition timing of the normal bank is set to an optimal ignition timing at which the output and thermal efficiency are maximized, that is, an MBT (Minimum Advance for the Best Torque). That is, it is delayed (closer to TDC) toward the low rotation-high load side, and advanced toward the high rotation-low load side. This is because the higher the load, the lower the residual gas ratio and the higher the combustion speed, and the higher the rotation speed, the stronger the turbulence level of the working gas, and the period viewed from the heat generation crank angle is almost constant regardless of the rotation speed. However, the change in absolute time from ignition to the start of heat generation is small, and the higher the speed, the larger the required crank angle. Therefore, it is necessary to advance the ignition timing.

  In step S24, the output torque of the normal side bank and the output torque of the failure side bank are controlled to be equal to each other through steps S22 to S23. This is because when the output torque in the failure side bank and the output torque in the normal side bank are greatly different, the output torque of the internal combustion engine varies and noise vibration increases and the riding comfort is impaired.

  In step S25, the air-fuel ratio A / F of the exhaust gas of each bank is detected based on the output value of the oxygen sensor 24 arranged in the exhaust passage 9 of each bank.

  In step S26, the fuel injection amount of the failure side bank is feedback controlled so that the air fuel ratio of the exhaust passage 9 of the failure side bank is maintained at the stoichiometric air fuel ratio (stoichiometric). The three-way catalysts 14R, 14L efficiently remove all the main harmful components (HC, CO, NOx) in the exhaust gas by the oxidation-reduction reaction only when the air-fuel ratio of the air-fuel mixture to be burned is in a narrow range near the theoretical air-fuel ratio. Purify. In order for these three-way catalysts 14R and 14L to function effectively, strict air-fuel ratio control is required in which the air-fuel ratio of the air-fuel mixture is adjusted to the center of a narrow range near the theoretical air-fuel ratio.

  For this reason, while the output of the oxygen sensor 24 is rich, the air-fuel ratio on the upstream side of the three-way catalyst 14R, 14L changes leaner by a certain amount, that is, on the upstream side of the three-way catalyst 14R, 14L. The sub-feedback correction amount is increased by a certain amount to the minus side so that the air-fuel ratio of the engine gradually approaches the lean side. On the other hand, while the output of the downstream oxygen sensor 24 indicates lean, the air-fuel ratio on the upstream side of the three-way catalysts 14R, 14L changes toward the rich by a certain amount, that is, the three-way catalysts 14R, 14L The sub feedback correction amount is increased by a certain amount to the plus side so that the upstream air-fuel ratio gradually approaches the rich side. By such sub-feedback control, the purification action of the three-way catalysts 14R, 14L is effectively utilized.

  In step S27, torque adjustment is performed by setting the ignition timing of the failure side bank to an ignition timing at which the thermal efficiency is maximum, that is, an optimal ignition timing at which MBT is obtained.

  In step S28, the fuel injection amount of each bank is feedback controlled so that the air-fuel ratio of the exhaust passage 9 of the normal bank is maintained at the stoichiometric air-fuel ratio (stoichiometric). At the same time, the ignition timing is set to an ignition timing at which the thermal efficiency is maximized, that is, an optimal ignition timing at which MBT is achieved, and torque adjustment is performed.

  In step S29, by executing the above steps S26 to S28, the torque of both banks is made equal and the vehicle is made to fail.

  The both bank failure control is executed by the ECM 10 as shown in FIG.

  First, in step S31, the air-fuel ratio A / F of the exhaust gas of each bank is detected based on the output value of the oxygen sensor 24 arranged in the exhaust passage 9 of each bank.

  In step S32, as in step S26, the fuel injection amount of each bank is feedback controlled so that the air-fuel ratio of the exhaust passages 9 of both banks is maintained at the stoichiometric air-fuel ratio (stoichiometric).

  In step S33, torque adjustment is performed by setting the ignition timing of both banks to an ignition timing at which the thermal efficiency is maximum, that is, an optimal ignition timing at which MBT is achieved.

  In step S34, by executing the above steps S32 to S33, the torque of both banks is made equal and the vehicle is caused to fail.

  12 and 13 are explanatory diagrams for explaining changes in the opening / closing timings and lift amounts of the exhaust valves 8 and the intake valves 4 when the VEL devices in one bank and both banks fail.

  When the VEL device in one bank shown in FIG. 12 fails, the intake valve 4 is opened and closed due to the failure of the VEL actuator 49 from the A state indicating the opening / closing timing and the lift amount of the exhaust valve 8 and the intake valve 4 in the normal state. When it is repeated, the control shaft 45 is urged in the small lift direction, the valve lift amount gradually decreases, and is returned to the stopper position that regulates the minimum lift amount, so that the intake air amount of the engine 1 cannot be secured (state B). ).

  However, by executing steps S8 to S9 of the VEL failure control, the valve timing is controlled to the retard side by the VTC device of the exhaust valve 8 of the bank as shown in the C state, and the exhaust valve 8 The secondary air is injected in the exhaust stroke to the intake stroke by the secondary air supply device 22 immediately downstream of the air, so that air is introduced into the combustion chamber 5 even through the exhaust valve 8 during the intake stroke.

  Therefore, the combustion of the combustion chamber 5 in the normal side bank (D state) and the combustion in the combustion chamber 5 of the failure side bank (C state) are alternately repeated, so that the vehicle can be made to fail.

  Moreover, since the combustion pressure in the combustion chamber 5 in the normal bank (D state) and the combustion pressure in the combustion chamber 5 in the failure side bank (C state) are controlled equally by steps S21 to S24, the internal combustion engine It is possible to prevent the driving feeling from being hindered by the output fluctuation being suppressed. In addition, since steps S25 to S28 are executed, it is possible to perform the fail travel without reducing the fuel consumption performance and the exhaust purification performance.

  At the time of failure of the VEL devices in both banks shown in FIG. 13, from the state A indicating the opening / closing timing and the lift amount of the exhaust valve 8 and the intake valve 4 in the normal state, the VEL actuators 49R and 49L in both banks When the opening and closing of the valve 4 is repeated, the control shaft 45 is urged in the small lift direction, the valve lift amount gradually decreases, and is returned to the stopper position that regulates the minimum lift amount. Cannot be secured (state B).

  However, by executing steps S8 to S9 of the VEL failure control, the valve timing is controlled to the retarded side by the VTC devices of the exhaust valves 8 of both banks as shown in the C state, and the exhaust valve 8 The secondary air is injected in the exhaust stroke to the intake stroke by the secondary air supply device 22 immediately downstream of the air, so that air is introduced into the combustion chamber 5 even through the exhaust valve 8 during the intake stroke.

  Accordingly, the vehicle can be made to fail by repeating the combustion in the combustion chamber 5 of one failure side bank and the combustion in the combustion chamber 5 of the other failure side bank alternately. In addition, since steps S31 to S33 are executed, it is possible to cause the vehicle to fail without deteriorating the fuel consumption performance and the exhaust purification performance.

  In the above embodiment, the description has been given of the application to the V-type internal combustion engine that includes the variable valve device for each bank and does not need to be added specially for fail-safe control. In this case, for example, in the case of a six-cylinder engine, one each for the cylinder group of cylinders # 1 to # 3 and the cylinder group of cylinders # 4 to # 6 is used as a variable valve system. What is necessary is just to set it as the structure provided. Furthermore, the present invention may be applied to an in-line internal combustion engine in which all cylinders are controlled by one variable valve operating device.

  In the present embodiment, the following effects can be achieved.

  (A) The internal combustion engine 1 is provided with an intake valve variable valve mechanism that makes the valve lift amount of the intake valve 4 variable, and an exhaust valve variable valve mechanism that makes the valve timing of the exhaust valve 8 variable. The secondary air supply device 22 for supplying secondary air downstream of each exhaust valve 8 for exhaust purification by the catalyst disposed in the exhaust passage 9 of the internal combustion engine 1 and the failure state of the variable valve mechanism for the intake valve are shown. Step S1 as a determination means, and an ECM 10 as a control means for controlling each of the variable valve mechanisms and the secondary air supply device, wherein the control means uses the failure state determination means to change the intake valve variable motion. When it is determined that the valve mechanism has failed, the secondary air supply device 22 is operated in the exhaust stroke or the intake stroke, and the exhaust valve is controlled by the exhaust valve variable valve mechanism. The closing timing and so as to retard after the top dead center to control retarded valve timing of the probe 8. For this reason, the secondary air injected downstream of the exhaust valve 8 is introduced into the combustion chamber 5 even through the exhaust valve 8 during the intake stroke, so that the vehicle can be made to fail.

  (A) The variable valve mechanism for intake valve is provided for each of a plurality of cylinder groups, the variable valve mechanism for exhaust valve is provided for each of a plurality of cylinder groups, and the control means is controlled by the failure state determination means. When it is determined that the variable valve mechanism for the intake valve of the cylinder group has failed, the secondary air supply device 22 is operated from the exhaust stroke to the intake stroke, and the exhaust valve for the cylinder group is operated. The valve timing of the exhaust valve 8 of the cylinder group is retarded by a variable valve mechanism so that the valve closing timing is retarded after top dead center. Therefore, the secondary air injected downstream of the exhaust valve 8 is also introduced into the combustion chamber 5 through the exhaust valve 8 during the intake stroke, and combustion in the combustion chamber 5 of the normal cylinder group and the failed cylinder By repeating the combustion in the combustion chambers 5 of the group alternately, the vehicle can be made to fail.

  (C) The ECM 10 as the control means adjusts the valve lift amount of the variable valve mechanism for the intake valve of the normal cylinder group according to the amount of air introduced into the cylinder group in which the variable valve mechanism for the intake valve has failed. As a result, there is no step in the alternate combustion pressure between the failure side cylinder group and the normal side cylinder group, and smooth fail-safe traveling is possible.

  (D) The ECM 10 as the control means corrects the fuel injection amount of the cylinder group according to the amount of air introduced into the cylinder group in which the intake valve variable valve mechanism has failed, and the normal intake valve variable valve Since the fuel injection amount of the corresponding cylinder group is corrected in accordance with the corrected valve lift characteristic of the mechanism, it is possible to perform the failure running without deteriorating the fuel consumption performance and the exhaust purification performance.

  (E) The ECM 10 as the control means corrects the fuel injection amount in accordance with the introduced air amount when the failure state determining means determines that the intake valve variable valve mechanism has failed. Even when the variable valve mechanism fails, it is possible to cause the vehicle to fail without degrading the fuel consumption performance and the exhaust purification performance.

  (F) The variable valve mechanism for the intake valve swings the camshaft 41 rotating in synchronization with the crankshaft and the drive cam 43 fixed to the camshaft 8A to swing the intake valve 4 by swinging. A control having a moving cam 42, transmission mechanisms 44, 47, 48 linked to the drive cam 43 side at one end and linked to the swing cam 42 side at the other end, and a control cam 46 for changing the attitude of the transmission mechanism. The intake valve 4 includes a shaft 45 and an actuator 49 that rotates the control shaft 45, and the lift characteristic of the intake valve 4 can be changed by controlling the rotation of the control shaft 45 by the actuator 49. With the variable valve mechanism having a configuration capable of changing the lift characteristics, the intake air amount of the cylinder group controlled by each variable valve mechanism can be controlled.

  (G) Since the cylinder group of the internal combustion engine 1 is provided for each bank of the V-type internal combustion engine, an intake air amount control system is provided for each bank in advance, and there is no need to add specially for fail-safe control. It can be implemented simply and at low cost.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine, engine 2 Intake passage 3 Electric throttle valve 4 Intake valve 5 Combustion chamber 6 Spark plug 7 Fuel injection valve 8 Exhaust valve 9 Exhaust passage 10 ECM
20, 20R, 20L VEL-C / U

Claims (7)

A variable valve mechanism for an intake valve that makes the valve lift amount of the intake valve variable in the internal combustion engine;
A variable valve mechanism for the exhaust valve that makes the valve timing of the exhaust valve variable;
A secondary air supply device for supplying secondary air downstream of each exhaust valve for exhaust purification by a catalyst disposed in an exhaust passage of the internal combustion engine;
Means for determining a failure state of the variable valve mechanism for the intake valve;
Control means for controlling each of the variable valve mechanisms and the secondary air supply device,
When the failure state determination means determines that the intake valve variable valve mechanism has failed, the control means operates the secondary air supply device in the exhaust stroke or the intake stroke, and An air quantity control device for an internal combustion engine, characterized in that a valve timing of an exhaust valve is retarded by a variable valve mechanism, and the valve closing timing is retarded after top dead center. The intake valve variable valve mechanism is provided for each of a plurality of cylinder groups;
The exhaust valve variable valve mechanism is provided for each of a plurality of cylinder groups,
The control means operates the secondary air supply device in the exhaust stroke or the intake stroke when the failure state determining means determines that the intake valve variable valve mechanism of any of the cylinder groups has failed. In addition, the valve timing of the exhaust valve of the cylinder group is retarded by the variable valve mechanism for the exhaust valve of the cylinder group, and the valve closing timing is retarded after top dead center. An air amount control device for an internal combustion engine according to claim 1.   The control means adjusts the valve lift amount of the variable valve mechanism for an intake valve of a normal cylinder group according to the amount of air introduced into the cylinder group in which the variable valve mechanism for the intake valve has failed. Item 3. The air amount control device for an internal combustion engine according to Item 2.   The control means corrects the fuel injection amount of the cylinder group according to the amount of air introduced into the cylinder group in which the intake valve variable valve mechanism has failed, and corrects the corrected valve of the normal intake valve variable valve mechanism. 4. An air amount control device for an internal combustion engine according to claim 3, wherein the fuel injection amount of the corresponding cylinder group is corrected in accordance with the lift characteristic.   2. The control unit according to claim 1, wherein the control unit corrects the fuel injection amount in accordance with the amount of introduced air when the failure state determination unit determines that the variable valve mechanism for the intake valve has failed. Air quantity control device for internal combustion engine. The variable valve mechanism for the intake valve is
A camshaft rotating in synchronization with the crankshaft;
A drive cam fixed to the camshaft;
A swing cam that opens and closes the intake valve by swinging;
A transmission mechanism linked to the drive cam side at one end and linked to the swing cam side at the other end;
A control shaft having a control cam for changing the attitude of the transmission mechanism;
An actuator that rotates the control shaft,
The air amount of the internal combustion engine according to any one of claims 1 to 5, wherein the lift characteristic of the intake valve can be changed by controlling the rotation of the control shaft by the actuator. Control device.   The air quantity control device for an internal combustion engine according to any one of claims 2 to 4, wherein a cylinder group of the internal combustion engine is provided for each bank of the V-type internal combustion engine.

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