JP4816627B2 - Actuator failure diagnosis device - Google Patents

Description

  The present invention relates to a failure diagnosis apparatus for an actuator used for an operation of a variable valve characteristic system of an internal combustion engine, for example.

  2. Description of the Related Art In recent years, a variable valve system that makes variable the valve characteristics of an intake valve and an exhaust valve, which are engine valves, according to engine operating conditions has been adopted in many on-vehicle internal combustion engines. For example, a variable valve timing system that varies the valve timing of the engine valve and a variable valve lift amount system that varies the valve lift amount of the engine valve have been put to practical use as such a variable valve system.

  FIG. 6 shows an example of the configuration of the variable valve lift system. As shown in the figure, the variable valve lift amount system includes an actuator 100, a control shaft 101, and a variable valve lift amount mechanism 102 provided for each cylinder of the internal combustion engine. A control shaft 101 driven in the axial direction by the actuator 100 is connected to a variable valve lift amount mechanism 102 of each cylinder, and operates the variable valve lift amount mechanism 102 in accordance with the displacement in the axial direction. The variable valve lift amount mechanism 102 is configured to increase or decrease the valve lift amount of the engine valve in accordance with its operation.

  Conventionally, devices described in, for example, Patent Literature 1 and Patent Literature 2 are known as devices for diagnosing a failure of an actuator that is used for the operation of such a variable valve lift amount system. In the failure diagnosis apparatus described in Patent Document 1, it is diagnosed that there is an abnormal operation of the actuator when the operation speed of the actuator is too slow. Further, in the failure diagnosis apparatus described in Patent Document 2, the presence of a failure in the variable valve lift amount system is diagnosed when the magnitude of the control command value commanded to the actuator deviates from the normal range.

  By the way, a failure due to the sticking of the actuator of such a variable valve lift amount system can be diagnosed in the following manner. That is, if the operation position of the actuator does not change despite the operation command being given to the actuator, it can be diagnosed that the sticking due to the biting of the foreign matter has occurred.

Such sticking of the actuator may occur only in any one of the operation directions. Therefore, the following modes can distinguish and detect the sticking of the actuator in each operation direction. That is, when one and the other end of the actuator operating range are closed and open, respectively, if the operating position does not change when the actuator is commanded to the open end, the actuator is locked on the closed end, that is, closed. If sticking occurs and the operation position of the actuator does not change when the actuator is commanded to the closed end side, it can be diagnosed separately that the actuator is stuck on the open end side, i.e., open sticking has occurred. it can.
JP 2007-170342 A JP 2006-63846 A

  By the way, as described above, when making a diagnosis by distinguishing between the closed adhesion and the open adhesion of the actuator, different diagnosis results are made for the trip at the time of occurrence of the failure and the next trip, despite the same failure. May end up.

  FIG. 7 shows an example of an actuator control mode in a situation where such a change in the diagnostic result occurs. Here, when the deviation of the actual operating position of the actuator from the target operating position is larger than the predetermined fixing determination value α on the closed end side, it is diagnosed that the closed closing of the actuator has occurred. Further, when the deviation is larger than the predetermined sticking determination value α on the open end side, it is diagnosed that the open sticking of the actuator has occurred.

  Now, at time t10 in FIG. 7, the operating position of the actuator is opened more than a predetermined sticking determination value α on the closed end side with respect to the target operating position of the actuator, and it is diagnosed that there is a closed sticking. . Here, the system is down at time t11 with the closed and fixed state.

  In the example shown in the figure, at the subsequent time t12, the next trip is started, that is, the system stopped at the time t11 is restarted. At this time, since the operating position of the actuator in which the closed adhering occurred cannot be determined in the previous trip, the operating position of the actuator at the start of the trip is unknown. Therefore, immediately after the start of the trip, reference position learning for confirming the operating position of the actuator is performed.

  This reference position learning is performed in the following manner. That is, when learning the reference position, the actuator is operated until it hits the open end of its operating range. At this time, if the actuator is moved to the open end side by the amount of movement from the closed end to the open end of the actuator operating range, the actuator can be moved to the operating range regardless of the operating position at the start of learning. It should be able to operate up to the open end. Then, the position when it hits the open end of the operation range is stored as a reference position, and thereafter, the operation position of the actuator is grasped from the relative operation amount of the actuator from the reference position. In the example shown in the figure, the actuator is instructed to operate at the open end of the operating range after assuming that the temporary operating position of the actuator at the start of the trip is at the closed end of the operating range. Thus, the reference position learning as described above is performed.

  When the reference position learning is completed at time t13, the system recognizes that the operating position of the actuator at that time is at the open end of the operating range. Accordingly, subsequent actuator operation commands are directed toward the closed end. If the actuator at this time is stuck following the previous trip, the operation position of the actuator may not change in response to the operation command to the closed end here. Therefore, in the example shown in the figure, the actuator is fixed open at the time t14 when the operating position of the actuator ascertained by the system opens more than a predetermined fixing determination value α on the open end side with respect to the target operating position of the actuator. It is diagnosed that it has occurred, and a diagnosis result that sticking in the direction opposite to the previous trip has occurred is made.

Such a problem occurs in common in the failure diagnosis apparatus for actuators configured as described in (a) to (b) below.
(A) When one end and the other end of the operating range of the actuator are “first end” and “second end”, respectively, when the operating position of the actuator is unknown when the system where the actuator is installed is The actuator is moved so as to abut on the second end, and the operation position at that time is learned as a reference position, and the operation position of the actuator is confirmed from the relative operation amount of the actuator from the learned reference position.
(B) When no change in the operation position of the actuator is confirmed in response to the operation command toward the first end, it is diagnosed that the sticking of the operation toward the first end of the actuator has occurred.
(C) When no change in the operation position of the actuator is confirmed in response to the operation command directed toward the second end, it is diagnosed that the sticking of the operation toward the second end of the actuator has occurred.

  The present invention has been made in view of such a situation, and the problem to be solved is preferably that the diagnosis result on the adhesion of the actuator changes as the failure diagnosis apparatus is restarted. It is an object of the present invention to provide an actuator failure diagnosis device that can be prevented.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
In order to solve the above-mentioned problem, in the invention described in claim 1, when one and the other ends of the operating range of the actuator are defined as the first end and the second end, respectively, When the operating position of the actuator is unknown, the actuator is operated so as to abut against the second end, the operating position at that time is learned as a reference position, and the relative position of the actuator relative to the learned reference position is determined. This is applied to an actuator whose operation position is confirmed from the operation amount, and when a change in the operation position of the actuator is not confirmed in response to an operation command toward the first end, the actuator is moved to the first end side of the actuator. It is diagnosed that the sticking of the operation has occurred, and the change in the operation position of the actuator with respect to the operation command toward the second end If not confirmed, in the failure diagnosis device for an actuator for diagnosing that the actuator is stuck to the second end side, the operation to the first end side after the failure diagnosis device is restarted. Even when a diagnosis result indicating that the sticking has occurred is made, if there is a diagnosis history that sticking has occurred with respect to the operation toward the second end side at the previous activation of the failure diagnosis apparatus, the second terminal The gist is to diagnose that the sticking to the side movement has occurred.

  In the above configuration, even when a diagnosis result indicating that the operation to the first end side has occurred after the failure diagnosis apparatus is restarted, the operation to the second end side is performed at the previous start of the failure diagnosis apparatus. When there is a diagnosis history that the sticking has occurred, regardless of the diagnosis result, it is diagnosed that the sticking of the operation toward the second end has occurred. Therefore, by learning the reference position after restarting, it is possible to suitably prevent the diagnosis result of the presence of closed sticking at the previous start-up from being switched to the diagnosis result of the presence of open sticking. It becomes like this.

  According to a second aspect of the present invention, in the failure diagnosis device for an actuator according to the first aspect, the diagnosis that the sticking of the movement toward the first end has occurred is the actual movement with respect to the target movement position. Diagnosis that the position deviation is larger than the prescribed sticking judgment value on the first end side and the sticking of the movement toward the second end side has occurred is actually performed with respect to the target action position. The gist is that the deviation of the operation position is performed when the deviation of the operation position is more than a predetermined sticking determination value on the second end side.

The diagnosis of the occurrence of sticking regarding the operation toward the first end side and the second end side as described above can be performed in the above-described manner.
According to a third aspect of the present invention, in the failure diagnosis apparatus for an actuator according to the first or second aspect, the actuator is used for an operation of a valve characteristic variable system that varies a valve characteristic of an engine valve of an internal combustion engine. Its gist is that it is a thing.

  Thus, the present invention can be embodied as a device for diagnosing a failure of an actuator that is used in the operation of a variable valve characteristic system that varies the valve characteristic of an engine valve of an internal combustion engine.

  According to a fourth aspect of the present invention, in the failure diagnosis apparatus for an actuator according to the first or second aspect, the actuator is used for an operation of a variable valve lift system that varies a valve lift amount of an engine valve of an internal combustion engine. It is the gist of what is done.

  Thus, the present invention can be embodied as a device for diagnosing a failure of an actuator that is used in the operation of a variable valve lift amount system that varies the valve lift amount of an engine valve of an internal combustion engine.

  As the variable valve lift system, for example, as described in claim 5, the control shaft that is moved in the axial direction by the actuator, and the valve lift amount is adjusted in conjunction with the axial movement of the control shaft. The present invention can be applied to a system including a variable valve lift amount mechanism.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an actuator failure diagnosis apparatus according to the present invention will be described in detail with reference to FIGS. In the present embodiment, when the present invention is embodied as an actuator failure diagnosis device used for an operation of a variable valve lift amount system in which the valve lift amount of an engine valve of an internal combustion engine is variable in accordance with an engine operating situation Will be explained.

FIG. 1 shows a configuration of a valve operating system of an internal combustion engine provided with a variable valve lift system to which the failure diagnosis apparatus of the present embodiment is applied.
As shown in the figure, the cylinder head 1H of the internal combustion engine 1 includes an intake camshaft 23 (shown in the upper left portion in FIG. 1) and an exhaust camshaft 24 (shown in the upper right portion in FIG. 1). ) Is rotatably supported. The intake camshaft 23 is provided with an intake cam 27. The intake cam 27 drives the intake valve 21, and the intake port 60 that opens to the combustion chamber is opened and closed. The exhaust camshaft 24 is provided with an exhaust cam 28. The exhaust cam 28 drives the exhaust valve 22, and the exhaust port 61 that opens to the combustion chamber is opened and closed.

  A roller rocker arm 26 having a roller 26 a is disposed below the exhaust cam shaft 24, and the roller 26 a is in contact with the exhaust cam 28. One end of the roller rocker arm 26 is supported by a lash adjuster 29 fixed to the cylinder head 1H, and the other end is in contact with the tappet 22a at the upper end of the exhaust valve 22. The end of the roller rocker arm 26 on the tappet 22 a side (the tappet side end 26 t) is biased by the valve spring 22 b of the exhaust valve 22. As a result, the roller 26 a is always in contact with the exhaust cam 28.

  The exhaust valve 22 is pressed by the exhaust cam 28 via the roller rocker arm 26, and is always opened and closed with a constant valve lift. On the other hand, on the intake valve 21 side, the valve drive force from the intake cam shaft 23 is transmitted to the intake valve 21 between the intake cam 27 and the roller rocker arm 25, and the valve lift amount is variable to change the valve lift amount. A mechanism 4 is interposed.

  One end of the roller rocker arm 25 is supported by a lash adjuster 29 fixed to the cylinder head 1H, and the other end is in contact with the tappet 21a at the upper end of the intake valve 21. The end portion of the roller rocker arm 25 on the tappet 21 a side (the tappet side end portion 25 t) is urged by the valve spring 21 b of the intake valve 21. In addition to the roller rocker arm 25, the pressure of the intake cam 27 is transmitted to the intake valve 21 via the variable valve lift amount mechanism 4.

  The variable valve lift amount mechanism 4 intakes the support pipe 41 fixed to the cylinder head 1H, the input portion 42 to which the valve driving force is input from the intake camshaft 23, and the valve driving force input to the input portion 42. A swing cam 43 or the like configured as an output unit for transmitting to the valve 21 is provided.

  The input unit 42 and the swing cam 43 include cylindrical housings 42 a and 43 a that are disposed on the support pipe 41 so as to be swingable about the axis of the support pipe 41. In this variable valve lift amount mechanism 4, one input portion 42 and two swing cams 43 are provided in pairs corresponding to the two intake valves 21 provided in the cylinder of the internal combustion engine 1. ing.

  An input arm 42b is formed in the housing 42a of the input portion 42 so as to protrude in the radial direction. A roller 42c that is in contact with the intake cam 27 is rotatably supported at the tip of the input arm 42b. In addition, the tip of the input arm 42b is urged so that the roller 42c is pressed against the intake cam 27 by a spring 44 disposed in a compressed state.

  An output arm 43b is formed on the housing 43a of the swing cam 43 so as to project in the radial direction. One surface of the output arm 43b is a cam surface 43c that is curved in a concave shape. The cam surface 43c is continuously and smoothly connected to the outer peripheral surface of the housing 43a other than the base circle portion of the housing 43a, that is, the portion where the output arm 43b protrudes, and the cam surface 43c and the base circle of the housing 43a are connected. The portion is in contact with the roller 25 a of the roller rocker arm 25.

  FIG. 2 shows a perspective sectional structure of the variable valve lift amount mechanism 4. As shown in the figure, the valve lift amount variable mechanism 4 is provided with two swing cams 43 with an input portion 42 interposed therebetween.

  The housings 42a and 43a of the input portion 42 and the swing cam 43 are each formed in a hollow cylindrical shape, and a support pipe 41 is inserted through them. A helical spline 42d formed in a spiral shape of a right-hand thread is formed on the inner periphery of the housing 42a of the input portion 42. On the other hand, on the inner periphery of the housing 43a of the swing cam 43, a helical spline 43d formed in a spiral shape of a left-hand screw is formed.

  A slider gear 45 is disposed in a series of internal spaces formed by the housings 42 a and 43 a of the input portion 42 and the two swing cams 43. The slider gear 45 is formed in a substantially hollow cylindrical shape, and is externally fitted on the support pipe 41 so as to be able to reciprocate in the axial direction of the support pipe 41 and to be relatively rotatable around the axis.

  A helical spline 45a formed in a spiral shape of a right-hand thread is formed on the outer peripheral surface of the central portion in the axial direction of the slider gear 45. The helical spline 45a is meshed with a helical spline 42d formed on the inner periphery of the housing 42a of the input portion 42. On the other hand, helical splines 45b formed in a spiral shape of a left-hand thread are formed on the outer peripheral surfaces of both end portions in the axial direction of the slider gear 45, respectively. The helical spline 45 b is meshed with a helical spline 43 d formed on the inner periphery of the housing 43 a of the swing cam 43.

  Between the helical spline 45a on the outer periphery of the slider gear 45 and each helical spline 45b, a small diameter portion 45c formed with an outer diameter smaller than those of the helical splines 45a and 45b is formed.

  Inside the support pipe 41 is provided a control shaft 46 that is slidably inserted in the axial direction thereof. The control shaft 46 can reciprocate in the support pipe 41 in the axial direction (directions of arrows R and L). In addition, the control shaft 46 and the slider gear 45 are engaged with each other by an appropriate locking member, thereby allowing the slider gear 45 to rotate with respect to the support pipe 41 while allowing the control shaft 46 to rotate. The slider gear 45 can be moved in the axial direction in accordance with the reciprocating motion in the axial direction.

  A drive unit 5 for operating the variable valve lift amount mechanism 4 is connected to the end of the control shaft 46. The drive unit 5 includes an actuator 47 formed of an electric motor and a conversion mechanism 48 that converts the rotational motion of the actuator 47 into a linear motion, and the converted linear motion is transmitted to the control shaft 46. In addition, the actuator 47 is provided with a rotation angle sensor 91 that outputs a signal for detecting the amount of rotation, and a reference position of the output shaft that is learned when the control shaft 46 is moved to the movable end. Based on the rotation amount of the output shaft from the reference position, the position of the control shaft 46 (hereinafter referred to as the stroke position) is detected.

  In the variable valve lift amount mechanism 4 configured as described above, when the control shaft 46 is moved in the axial direction by driving the actuator 47, the slider gear 45 is also moved in the axial direction along with this movement. Here, since the input portion 42, the swing cam 43, and the slider gear 45 are engaged with each other by a helical spline, when the slider gear 45 is moved in the axial direction in this way, the axis around the support pipe 41 is rotated. The relative phase between the input arm 42b and the output arm 43b is changed. By changing the relative phase, the swinging mode of the roller rocker arm 25 is changed. As a result, the maximum lift amount VL of the intake valve 21 and the operating angle INCAM corresponding to the valve opening period of the intake valve 21 are shown in FIG. As such, it is continuously variable.

  More specifically, as the control shaft 46 is moved in the direction of the arrow R shown in FIG. 2, the relative phase between the input arm 42b and the output arm 43b increases, thereby causing the roller rocker arm 25 to swing. As the value increases, the maximum lift amount VL and the working angle INCAM increase. On the contrary, as the control shaft 46 is moved in the direction of the arrow L shown in FIG. 2, the relative phase between the input arm 42b and the output arm 43b becomes smaller. The lift amount VL and the working angle INCAM are reduced.

  Control of such a variable valve lift amount system is performed by the electronic control unit 7. The electronic control unit 7 is a central processing unit (CPU) for executing arithmetic processing related to engine control, a memory for storing programs and various information necessary for engine control, and input / output of signals from / to the outside. It has an input port and an output port. The electronic control unit 7 also includes a nonvolatile memory 7a made of SRAM, EEPROM, or the like for storing and holding the results of self-diagnosis even during a system down.

  Signals from various sensors such as an air flow meter, a crank angle sensor, and an accelerator sensor are input to the input port of the electronic control unit 7. The output port of the electronic control unit 7 is connected to a fuel injection valve, a spark plug, a drive circuit for driving the actuator 47 and the like.

  Then, the electronic control unit 7 controls the operation of the variable valve lift amount mechanism 4 so that the valve characteristic of the intake valve 21 becomes a characteristic according to the engine operating condition. That is, the target intake air amount GAp is set based on the accelerator operation amount ACCP, the engine rotational speed NE, and the like so that the intake air amount introduced into the combustion chamber becomes an appropriate amount according to the engine operating condition. The target maximum lift amount VLp is calculated so that the target intake air amount GAp is obtained. Then, a target stroke position Sp that is a stroke position S corresponding to the target maximum lift amount VLp is calculated, and the rotation amount (operation amount) of the actuator 47 is controlled so that the actual stroke position S coincides with the target stroke position Sp. . In this embodiment, the actual stroke position S corresponds to the “operation position” of the actuator 47, and the target stroke position Sp corresponds to the “target operation position” of the actuator 47.

  Incidentally, hereinafter, the range that the stroke position S of the actuator 47 can take, that is, one and the other ends of the operation range of the actuator 47 are referred to as “closed end” and “open end”, respectively. Here, the closed end is the end of the operating range of the actuator 47 on the side where the maximum valve lift amount of the intake valve 21 is the smallest, and the open end is the end of the actuator 47 on the side where the maximum valve lift amount of the intake valve 21 is maximum. Each end of the operating range is shown. In the present embodiment, the closed end corresponds to the “first end” and the open end corresponds to the “second end”.

In the present embodiment, the electronic control unit 7 diagnoses the occurrence of sticking of the actuator 47 when controlling the operation of the variable valve lift amount mechanism 4 in the above-described manner. The diagnosis of the occurrence of sticking here is performed in the following modes (a) and (b).
(A) When the deviation of the actual stroke position S from the target stroke position Sp is greater than or equal to the predetermined sticking determination value α on the closed end side, the sticking about the operation of the actuator 47 on the open end side, that is, the closed end side It is diagnosed that the closed sticking, which is the sticking of the actuator 47, has occurred. That is, when the change of the stroke position S of the actuator 47 is not sufficiently confirmed with respect to the operation command toward the open end side, it is diagnosed that the closed sticking has occurred.
(B) When the deviation of the actual stroke position S from the target stroke position Sp is greater than or equal to the predetermined sticking determination value α on the open end side, the sticking of the actuator 47 to the closed end side, that is, the open end side It is diagnosed that an open sticking that is the sticking of the actuator 47 has occurred. That is, when the change of the stroke position S of the actuator 47 is not sufficiently confirmed with respect to the operation command toward the closed end side, it is diagnosed that the open sticking has occurred.

  At the time of diagnosis of the occurrence of the closed sticking and the open sticking, the electronic control unit 7 stops the operation control of the normal valve lift amount varying mechanism 4 as described above, and performs the fail process. Further, the electronic control unit 7 is configured to store a diagnostic code corresponding to each sticking in the nonvolatile memory 7a at the time of diagnosis of occurrence of the closed sticking and the open sticking. That is, in the trip after the trip when the sticking diagnosis is made, the diagnosis code that the closed sticking or the open sticking has occurred in the previous trip is stored in the nonvolatile memory 7a. It can be confirmed by whether or not.

  The electronic control unit 7 confirms the stroke position S of the actuator 47 by the operation amount of the actuator 47 relative to the reference position with the open end of the operation range as the reference position. Normally, when the system is down, that is, when the ignition switch is turned off, the electronic control unit 7 stores the stroke position S at that time in the nonvolatile memory 7a, and when the system is restarted, that is, when the next ignition switch is turned on. The stroke position S of the actuator 47 is confirmed from the memory.

  However, the stroke position S at which the sticking occurs cannot be strictly specified when the closed sticking or the open sticking occurs. Therefore, after the sticking occurs, the stroke position S of the actuator 47 becomes unknown. Therefore, when sticking occurs, the stroke position S cannot be stored when the system is down.

  On the other hand, when the stroke position S of the actuator 47 is unknown at the time of system restart, that is, when the stroke position S is not stored in the nonvolatile memory 7a, the electronic control unit 7 learns the reference position for confirming the reference position. To implement. This reference position learning is performed in the following manner. That is, when learning the reference position, the actuator 47 is forcibly operated by an amount necessary for the operation from the closed end to the open end of the operation range so that the actuator 47 is abutted against the open end of the operation range. Then, the stroke position S at that time is stored as a reference position, and thereafter, the operation position of the actuator 47 is grasped from the relative operation amount from the reference position.

  In this case, if the system is down after the diagnosis of the occurrence of closed sticking and the reference position learning is performed at the time of subsequent system restart, the sticking state is the same as described above, but sticking in the opposite direction from the previous time is performed. In some cases, the diagnosis result that the occurrence has occurred is made, that is, the diagnosis result is switched from the closed fixation to the open fixation. That is, when the closed fixing occurs and the system is shut down without the stroke position S of the actuator 47 being stored in the nonvolatile memory 7a, the electronic control unit 7 performs the reference position learning when the system is restarted thereafter. become. When the reference position learning is completed, the electronic control unit 7 recognizes that the actual stroke position S is at the open end of the operating range of the actuator 47 regardless of the actual stroke position S. After that, an operation command is given to the actuator 47 so as to move the stroke position S to the closed end side. If no change in the stroke position S is confirmed with respect to the operation command, a diagnosis of occurrence of open sticking is made. It will end up.

  Therefore, in the present embodiment, the electronic control unit 7 prevents such switching of the diagnosis result by performing diagnosis in the following manner. In other words, the electronic control unit 7 also has a diagnostic code indicating that closed sticking has occurred during the previous startup of the system (previous trip) even when a diagnosis result indicating that open sticking has occurred after the system has been restarted. Is stored in the non-volatile memory 7a, it is diagnosed that the closed sticking has occurred regardless of the diagnosis result at that time.

  FIG. 4 shows an example of the control mode of the actuator failure diagnosis apparatus according to this embodiment. At time t1 in the figure, since the change in the stroke position S of the actuator 47 is not confirmed in response to the operation command to the open end side, a diagnosis that there is a closed sticking is made. At this time, the diagnosis result of the closed sticking is stored in the nonvolatile memory 7a as a history. In this case, the system is down at the subsequent time t2 with the closed and fixed state.

  In the example shown in the figure, at the subsequent time t3, the next trip is started, that is, the system stopped at the time t2 is restarted. In this case, due to the occurrence of closed fixation in the previous trip, the system is brought down without the stroke position S of the actuator 47 being stored in the nonvolatile memory 7a. Therefore, the electronic control unit 7 performs the reference position learning immediately after the system is restarted.

  When the reference position learning is completed at time t4, the electronic control unit 7 recognizes that the stroke position S at that time is at the open end of the actuator operating range that is the reference position. Therefore, the subsequent operation command for the actuator 47 is first directed toward the closed end. If the actuator 47 at this time is stuck after the previous trip, the stroke position S of the actuator 47 does not change in response to the operation command to the closed end here. For example, at time t5, as shown by the broken line in FIG. However, in this embodiment, if the non-volatile memory 7a stores a diagnosis history indicating that closed sticking occurred in the previous trip, it is also diagnosed that there is closed sticking. Therefore, even after the system is restarted, the diagnosis result that there is a closed sticking is maintained.

  FIG. 5 shows a flowchart of a sticking diagnosis routine for performing the sticking diagnosis process in the above-described mode. The processing of this routine is periodically executed by the electronic control unit 7 during the operation control of the normal valve lift amount varying mechanism 4 described above.

  When this routine is started, the electronic control unit 7 first determines in step S10 whether or not the stroke position S of the actuator 47 does not change despite the operation command to the closed end. Confirm. If it is not in this state (S10: NO), the electronic control unit 7 ends the processing of this routine as it is.

  On the other hand, if it is in the above state (S10: YES), the electronic control unit 7 confirms the diagnosis history stored in the nonvolatile memory 7a, and whether or not a diagnosis of the presence of closed sticking has been made in the previous trip. Confirm. Here, if such a diagnosis history is not stored (S20: NO), the electronic control unit 7 performs a diagnosis of presence of open fixation in step S30, and if stored (S20: YES), the electronic control unit 7 closes in step S40. Diagnose that there is sticking. After these diagnoses, the electronic control unit 7 ends the processing of this routine.

According to the actuator failure diagnosis apparatus of the present embodiment described above, the following effects can be obtained.
In the present embodiment, the closed adhering and the open adhering of the actuator 47 are diagnosed in the manner shown in (a) and (b) above. When the stroke position S of the actuator 47 is unknown at the time of starting the system, the actuator 47 is brought into contact with the open end of the operation range to learn the reference position. In this embodiment, even if a diagnosis result indicating that there is an open sticking is made after the system is restarted, if there is a diagnosis history indicating that there is a closed sticking at the previous system start-up, the closing is performed regardless of the diagnosis result. Diagnosis that there is sticking is made. Therefore, by performing the reference position learning after the system is restarted, it is possible to suitably prevent the diagnosis result of the presence of closed sticking at the previous system start-up from being switched to the diagnosis result of the presence of open sticking. It becomes like this.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the closed sticking and the open sticking are diagnosed when the deviation of the stroke position S from the target stroke position Sp is equal to or larger than the prescribed sticking judgment value α on the open end side and the closed end side. Other fixing diagnosis methods may be employed. For example, the occurrence of closed sticking or open sticking can be diagnosed based on the operating speed of the actuator 47 when an operation command is given to the open end side or the closed end side.

In the above embodiment, the control shaft 46 is moved in the axial direction by the actuator 47, and the variable valve lift amount mechanism 4 that adjusts the valve lift amount in conjunction with the axial movement of the control shaft 46 is provided. The case where the present invention is embodied as an apparatus for diagnosing a failure of the actuator 47 used for the operation of the variable valve lift amount system has been described. However, the present invention can be implemented as a failure diagnosis device for an actuator used for the operation of a variable valve lift amount system having any other configuration as long as the valve lift amount of the engine valve of the internal combustion engine is variable. it can. The present invention is also realized as a failure diagnosis device for an actuator used for operation of a variable valve characteristic system other than a variable valve lift amount system, such as a variable valve timing system, as long as the valve characteristic of the internal combustion engine is variable. You can also Furthermore, the present invention can also be embodied as an actuator failure diagnosis device employed in any system other than the variable valve characteristic system. In short, the present invention can be applied to any actuator failure diagnosis device that satisfies the following three requirements (d) to (f).
(D) When one end and the other end of the operating range of the actuator are the first end and the second end, respectively, and when the operating position of the actuator is unknown at the start of the system in which the actuator is installed, It is applied to an actuator that is operated so as to abut against the second end, learns the operation position at that time as a reference position, and whose operation position is confirmed based on the relative operation amount of the actuator from the learned reference position. That.
(E) When no change in the operation position of the actuator is confirmed in response to the operation command directed toward the first end, diagnosis that the sticking to the operation of the actuator toward the first end has occurred.
(F) When no change in the operating position of the actuator is confirmed in response to the operation command directed toward the second end, diagnosis is made that the actuator is stuck to the second end side.

1 is a cross-sectional view showing a cross-sectional structure of a cylinder head of an internal combustion engine that employs a variable valve lift system that is an application target of an embodiment of an actuator failure diagnosis apparatus according to the present invention. The figure which combines the cross-sectional view which shows the perspective cross-section structure of the valve lift amount variable mechanism of the valve lift amount variable system which becomes the application object of the embodiment, and the schematic diagram which shows the structure of the control system typically. The schematic diagram which shows the variable setting aspect of the maximum lift amount and working angle by the valve lift amount variable mechanism of the valve lift amount variable system used as the application object of the embodiment. The time chart which shows an example of the control aspect about the failure diagnosis apparatus of the actuator of the embodiment. The flowchart which shows the process sequence of the sticking diagnosis routine applied to the failure diagnosis apparatus of the actuator of the embodiment. The schematic diagram which shows the structure typically about an example of a valve lift amount variable mechanism. The time chart which shows an example of the control aspect about the failure diagnosis apparatus of the conventional actuator.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 1H ... Cylinder head, 4 ... Valve lift amount variable mechanism, 5 ... Drive part, 7 ... Electronic control unit, 7a ... Non-volatile memory, 21 ... Intake valve, 21a ... Tappet, 21b ... Valve spring, 22 Exhaust valve, 22a ... Tappet, 22b ... Valve spring, 23 ... Intake camshaft, 24 ... Exhaust camshaft, 25 ... Roller rocker arm, 25a ... Roller, 26 ... Roller rocker arm, 26a ... Roller, 27 ... Intake cam, 28 ... Exhaust cam 29 ... Rush adjuster 41 ... Support pipe 42 ... Input part 42a ... Housing 42b ... Input arm 42c ... Roller 42d ... Helical spline 43 ... Swing cam 43a ... Housing 43b ... Output arm 43c ... cam surface, 43d ... helical spline, 44 ... spring, 45 Slider gear, 45a, 45b ... helical splines, 45 c ... smaller diameter portion, 46 ... control shaft, 47 ... actuator, 48 ... conversion mechanism, 60 ... intake port, 61 ... exhaust port, 91 ... rotational angle sensor.

Claims (5)

When one end and the other end of the operating range of the actuator are the first end and the second end, respectively, and the operating position of the actuator is unknown at the time of starting the system where the actuator is installed, the actuator is moved to the second end. Applied to an actuator whose operation position is confirmed from the amount of operation of the actuator relative to the learned reference position, and learning the operation position at that time as a reference position.
When a change in the operating position of the actuator is not confirmed in response to an operation command directed toward the first end, it is diagnosed that the actuator is stuck to the first end, and the second In the failure diagnosis device for an actuator for diagnosing that the sticking of the operation to the second end side of the actuator has occurred when the change in the operation position of the actuator is not confirmed with respect to the operation command toward the end,
Even when a diagnosis result indicating that the operation to the first end side has occurred after the failure diagnosis apparatus is restarted, the operation to the second end side is performed at the previous start of the failure diagnosis apparatus. When there is a diagnosis history that the sticking has occurred, it is diagnosed that the sticking of the operation toward the second end has occurred. The diagnosis that the sticking of the movement to the first end side has occurred is that the deviation of the actual operation position with respect to the target operation position of the actuator is more than a predetermined sticking judgment value on the first end side. Done,
The diagnosis that the sticking of the movement toward the second end side has occurred is that the deviation of the actual operation position with respect to the target operation position of the actuator is more than a prescribed sticking judgment value on the second end side. The failure diagnosis device for an actuator according to claim 1, wherein the failure diagnosis device is performed. The actuator failure diagnosis apparatus according to claim 1, wherein the actuator is used for an operation of a valve characteristic variable system that varies a valve characteristic of an engine valve of an internal combustion engine. The actuator failure diagnosis apparatus according to claim 1, wherein the actuator is used for an operation of a variable valve lift amount system that varies a valve lift amount of an engine valve of an internal combustion engine. The variable valve lift amount system includes a control shaft that is moved in the axial direction by the actuator, and a variable valve lift amount mechanism that adjusts the valve lift amount in conjunction with the axial movement of the control shaft. 4. The actuator failure diagnosis device according to 4.

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