JP2007321712A - Diagnostic device for variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To diagnose a fail safe function of a variable valve gear capable of varying open characteristics of an engine valve and including the fail safe function setting open characteristics at a time of drive stop as reference characteristics. <P>SOLUTION: Whether or not diagnosis permission conditions are satisfied is determined based on an engine operation condition. When it is determined that the conditions are satisfied, drive of a VEL mechanism capable of varying lift (operating angles) of an intake valve is forcibly stopped, minimum speed VLRATE when open characteristics of the intake valve is changed to the minimum lift characteristics is calculated. The fail safe function is diagnosed by comparing the change speed VLRATE with a predetermined value NGLVL for diagnosis determination calculated based on engine speed and engine temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism that is provided in an internal combustion engine so that the opening characteristics of an intake valve and an exhaust valve can be varied, and that the opening characteristics become reference characteristics when supply of driving force is stopped. The present invention relates to a technique for diagnosing a function that becomes a reference characteristic when the drive is stopped.

In Patent Document 1, when a hydraulic control is stopped in a variable valve mechanism that drives a camshaft equipped with a three-dimensional cam by hydraulic control and continuously changes the lift and operating angle of the intake valve. By making the stable position where the camshaft heads and the stable position when the hydraulic pressure is not supplied to the actuator the same, stable when oil pump failure or failure to stop power supply to the electromagnetic solenoid An apparatus is disclosed that is configured to move naturally to a minimum lift that is in position.
JP 2000-110528 A

However, in the case of Patent Document 1, when an abnormality occurs in which the camshaft is fixed due to, for example, a foreign object being caught, there is a problem that it becomes difficult to move the camshaft to a stable position. It was insufficient.
The present invention has been made by paying attention to such a conventional problem. When the variable valve mechanism stops driving, whether the function of the intake / exhaust valve opening function as the reference position operates normally. The purpose is to diagnose.

For this reason, the invention according to claim 1
A variable valve mechanism diagnostic device configured to vary an opening characteristic of an intake valve or an exhaust valve of an internal combustion engine and to have the opening characteristic become a reference characteristic when supply of driving force is stopped,
Diagnosis permission determination means for performing diagnosis permission determination based on the engine operating state;
Driving stop means for forcibly stopping the supply of driving force to the variable valve mechanism when the diagnosis is permitted;
A change speed calculating means for calculating a change speed when the open characteristic changes to the reference characteristic by stopping the driving force supply of the variable valve mechanism by the drive stop means;
Diagnostic means for diagnosing whether there is an abnormality in the function whose opening characteristic becomes a reference characteristic when the variable valve mechanism is stopped based on the calculated change speed;
It is characterized by including.

According to the invention of claim 1,
When diagnosis of the variable valve mechanism is permitted based on the engine operating state, supply of driving force to the variable valve mechanism is forcibly stopped.
Here, a fail-safe function that changes to the reference characteristics based on the rate of change when the intake / exhaust valve opening characteristics change to the reference characteristics when the supply of driving force to the variable valve mechanism is stopped (hereinafter referred to as drive stop) Diagnose the presence or absence of abnormalities. Specifically, when the change rate is too small, it is diagnosed that the fail-safe function is abnormal.

In this way, the presence or absence of an abnormality in the fail-safe function when the variable valve mechanism is stopped is diagnosed during operation in advance, so that when it is determined as abnormal, it can be quickly repaired. it can.
Similarly, when it is diagnosed that there is an abnormality in the fail-safe function due to the drive stop of the variable valve mechanism, fail-safe control different from this can be performed to ensure good driving performance.

In addition, for example, when the variable valve mechanism stops driving, the intake / exhaust valve opening characteristics do not become the reference characteristics, and this failure is detected and switched to another failsafe control. In this case, it is difficult to ensure a good fail-safe function due to a delay in switching.
Therefore, in the present invention, by making the diagnosis based on the change speed, an abnormality occurs in a state in which the change to the reference characteristic is delayed before the fail-safe function at the time of stopping the driving of the variable valve mechanism completely fails. , It is possible to secure a good fail-safe function by switching to another fail-safe control in advance.

The invention according to claim 2
When an abnormality is diagnosed by the diagnosis means, an abnormality alarm is transmitted or stored.
According to the invention of claim 2,
When the abnormality is informed, the abnormality can be quickly repaired.

The invention according to claim 3
The variable valve mechanism for the intake valve is characterized in that when the diagnosis means diagnoses that there is an abnormality, the throttle valve upstream of the intake valve is throttled.
According to the invention of claim 3,
When the fail-safe function when the variable valve mechanism is stopped is abnormal, fail-safe control for reducing the intake air amount can be performed by throttle control of the throttle valve.

The invention according to claim 4
The variable valve mechanism is a mechanism for changing at least one of a valve lift or an operating angle of an intake valve, and a condition for permitting diagnosis by the diagnosis permission determining unit is that the change in the valve lift or the operating angle is In the high load region, the change in the intake air amount is small.

According to the invention of claim 4,
Since the diagnosis is permitted when the change in the intake air amount is small, it is possible to minimize the deterioration of the driving performance due to the diagnosis.

FIG. 1 is a configuration diagram of an internal combustion engine for a vehicle in the embodiment.
In FIG. 1, an electronic control throttle 104 that opens and closes a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of the internal combustion engine 101, and the combustion chamber is connected via the electronic control throttle 104 and the intake valve 105. Air is inhaled into 106.

The combustion exhaust is discharged from the combustion chamber 106 through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.
The exhaust valve 107 is driven to open and close by a cam 111 pivotally supported on the exhaust side camshaft 110 while maintaining a constant lift amount and operating angle (crank angle from opening to closing).
On the other hand, on the intake valve 105 side, a variable valve event and lift (VEL) mechanism 112 that continuously varies the valve lift amount of the intake valve together with the operating angle is provided.

Similarly, the intake valve 105 side is configured with a mechanism that continuously and variably controls the rotational phase difference between the crankshaft and the intake side camshaft to advance or retard the valve timing (valve opening / closing timing) of the intake valve 105. VTC (Variable valve Timing Control) mechanisms 113 are provided at both ends of the intake camshaft.
The VTC mechanism 201 is a mechanism that changes the valve timing of the intake valve 105 by changing the rotational phase of the intake camshaft 134 with respect to the crankshaft 120. In this embodiment, a spiral radial link type as will be described later. The variable valve timing mechanism is adopted.

In the present embodiment, the VTC mechanism 201 is provided only on the intake valve 105 side, but the variable valve timing mechanism is provided on the exhaust valve 107 side instead of the intake valve 105 side or together with the intake valve 105 side. It may be.
In addition, an electromagnetic fuel injection valve 131 is provided in the intake port 130 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal from an engine control unit (ECU) 114, a predetermined value is set. The fuel adjusted to the pressure is injected toward the intake valve 105.

Detection signals from various sensors are input to the ECU 114 incorporating the microcomputer, and the electronic control throttle 104, the VTC mechanism 201, and the fuel injection valve 131 are controlled by arithmetic processing based on the detection signals.
The various sensors include an air flow meter 115 for detecting the intake air amount Q of the engine 101, an accelerator opening sensor APS116 for detecting the accelerator opening, and a reference crank angle signal REF (reference rotation for each crank angle of 180 ° from the crankshaft 120). Position angle signal) and a unit angle signal POS for each unit crank angle, a throttle sensor 118 for detecting the opening TVO of the throttle valve 103b, and a water temperature sensor 119 for detecting the coolant temperature of the engine 101 (or lubricating oil). An oil temperature sensor for detecting temperature), and a cam angle sensor 202 for taking out a cam signal CAM (reference rotation position signal) for each cam angle 90 ° (crank angle 180 °) from the intake side camshaft 134.

The ECU 114 calculates the engine rotational speed Ne based on the cycle of the reference crank angle signal REF or the number of unit angle signals POS generated per unit time.
2 to 4 show the structure of the VEL mechanism 112 in detail.
The variable valve lift mechanism shown in FIGS. 2 to 4 includes a pair of intake valves 105, 105, a hollow camshaft 13 (drive shaft) rotatably supported by the camshaft receiver 14 of the cylinder head 11, Two eccentric cams 15 and 15 (drive cams), which are rotational cams supported on the camshaft 13, and a control shaft 16 rotatably supported by the same camshaft receiver 14 above the camshaft 13. A pair of rocker arms 18, 18 supported on the control shaft 16 via a control cam 17 so as to be swingable, and a pair of rocker arms 19, 19 disposed at upper ends of the intake valves 105, 105 via valve lifters 19, 19. Independent rocking cams 20 and 20 are provided.

The eccentric cams 15 and 15 and the rocker arms 18 and 18 are linked by link arms 25 and 25, and the rocker arms 18 and 18 and the swing cams 20 and 20 are linked by link members 26 and 26.
The rocker arms 18, 18, the link arms 25, 25, and the link members 26, 26 constitute a transmission mechanism.

As shown in FIG. 5, the eccentric cam 15 has a substantially ring shape and includes a small-diameter cam main body 15a and a flange portion 15b integrally provided on the outer end surface of the cam main body 15a. A camshaft insertion hole 15 c is formed through the shaft, and the axis X of the cam body 15 a is eccentric from the axis Y of the camshaft 13 by a predetermined amount.
The pair of eccentric cams 15 are press-fitted and fixed to the camshaft 13 on both outer sides that do not interfere with the valve lifter 19 through camshaft insertion holes 15c, and the outer peripheral surface 15d of the cam body 15a is the same. The cam profile is formed.

As shown in FIG. 4, the rocker arm 18 is bent in a substantially crank shape, and a central base portion 18 a is supported by the control cam 17 in a self-rotating manner.
Also, a pin hole 18d into which a pin 21 connected to the tip of the link arm 25 is press-fitted is formed in one end 18b protruding from the outer end of the base 18a, while the inner end of the base 18a A pin hole 18e into which a pin 28 to be connected to an end portion 26a (described later) of each link member 26 is press-fitted is formed in the other end portion 18c protruding from the portion.

The control cam 17 has a cylindrical shape, is fixed to the outer periphery of the control shaft 16, and the position of the axis P1 is eccentric from the axis P2 of the control shaft 16 by α as shown in FIG.
As shown in FIGS. 2, 6, and 7, the rocking cam 20 has a substantially horizontal U shape, and a cam shaft 13 is fitted into a substantially annular base end portion 22 so as to be rotatably supported. A support hole 22a is formed through, and a pin hole 23a is formed through the end 23 located on the other end 18c side of the rocker arm 18.

Further, a base circle surface 24a on the base end portion 22 side and a cam surface 24b extending in an arc shape from the base circle surface 24a toward the end edge side of the end portion 23 are formed on the lower surface of the swing cam 20. The circular surface 24 a and the cam surface 24 b come into contact with predetermined positions on the upper surfaces of the valve lifters 19 in accordance with the swing position of the swing cam 20.
That is, when viewed from the valve lift characteristics shown in FIG. 8, as shown in FIG. 2, the predetermined angle range θ1 of the base circle surface 24a becomes the base circle section, and the predetermined angle range θ2 from the base circle section θ1 of the cam surface 24b changes. This is a so-called ramp section, and further, a predetermined angle range θ3 from the ramp section θ2 of the cam surface 24b is set to be a lift section.

The link arm 25 includes an annular base portion 25a and a projecting end 25b projecting at a predetermined position on the outer peripheral surface of the base portion 25a. At the center position of the base portion 25a, the cam body of the eccentric cam 15 is provided. A fitting hole 25c is formed in the outer peripheral surface of 15a so as to be freely rotatable, and a pin hole 25d through which the pin 21 is rotatably inserted is formed in the protruding end 25b.
Further, the link member 26 is formed in a straight line having a predetermined length, and circular pin ends 26a and 26b have pin holes 18d in the other end 18c of the rocker arm 18 and the end 23 of the swing cam 20, respectively. , 23a, and pin insertion holes 26c and 26d through which end portions of the pins 28 and 29 are rotatably inserted are formed.

In addition, snap rings 30, 31, and 32 that restrict the axial movement of the link arm 25 and the link member 26 are provided at one end of each pin 21, 28, and 29.
In the above configuration, the lift amount varies as shown in FIGS. 6 and 7 depending on the positional relationship between the axis P2 of the control shaft 16 and the axis P1 of the control cam 17, and the control shaft 16 is driven to rotate. As a result, the position of the axis P2 of the control shaft 16 with respect to the axis P1 of the control cam 17 is changed.

  The control shaft 16 is driven to rotate within a predetermined rotation angle range between a minimum angle position and a maximum angle position defined by a stopper by a DC servo motor (actuator) 121 with the configuration shown in FIG. By changing the operating angle of the control shaft 16 by the actuator 121, the lift amount and the operating angle of the intake valve 105 change continuously (see FIG. 9).

In FIG. 10, the DC servo motor 121 is arranged so that its rotation shaft is parallel to the control shaft 16, and a bevel gear 122 is pivotally supported at the tip of the rotation shaft.
On the other hand, a pair of stays 123a and 123b are fixed to the tip of the control shaft 16, and a nut 124 is swingably supported around an axis parallel to the control shaft 16 connecting the tips of the pair of stays 123a and 123b. The

A bevel gear 126 meshed with the bevel gear 122 is pivotally supported at the tip of the screw rod 125 meshed with the nut 124, and the screw rod 125 is rotated by the rotation of the DC servo motor 121. The position of the nut 124 that meshes with the 125 is displaced in the axial direction of the screw rod 125 so that the control shaft 16 is rotated.
Here, the direction in which the position of the nut 124 is brought closer to the bevel gear 126 is a direction in which the lift amount is reduced, and conversely, the direction in which the position of the nut 124 is moved away from the bevel gear 126 is a direction in which the lift amount is increased. .

  As shown in FIG. 10, a Hall IC type rotation angle sensor 127 for detecting the rotation angle REVEL of the control shaft 16 is provided at the tip of the control shaft 16, and the actual detected by the rotation angle sensor 127 is provided. The control unit 114 feedback-controls the DC servo motor 121 such that the rotation angle of the DC servo motor 121 matches the target rotation angle. Here, since the lift amount and the operating angle can be changed simultaneously by the rotation angle control of the control shaft 16, the rotation angle sensor 127 is a sensor that detects the lift amount at the same time as detecting the operating angle of the intake valve 105.

Next, the configuration of the VTC mechanism 201 will be described with reference to FIGS.
As shown in FIG. 11, the VTC mechanism 201 is assembled to the intake side camshaft 13 and the front end portion of the camshaft 13 so as to be relatively rotatable as necessary, and a chain (not shown) is attached. A drive ring 303 (drive rotary body) having a timing sprocket 302 linked to the crankshaft 120 via the outer periphery thereof, and the drive ring 303 and the camshaft 13 disposed on the front side (left side in FIG. 11). , 301, an assembly angle operation mechanism 304 that operates the assembly angle, an operation force applying means 305 that is disposed further forward of the assembly angle operation mechanism 304 and drives the mechanism 304, and an internal combustion engine An unillustrated VT that is mounted across the front surface of the outer cylinder head and the head cover and covers the front surface and peripheral area of the assembly angle operation mechanism 304 and the operation force applying means 305. And it includes a cover, a.

The drive ring 303 is formed in a short shaft cylindrical shape having a step-like insertion hole 306, and the insertion hole 306 portion rotates to a driven shaft member 307 (driven rotating body) coupled to the front end portion of the camshaft 13. It is assembled as possible.
As shown in FIG. 12, three radial grooves 308 (radial guides) having parallel side walls facing each other are provided on the front surface of the drive ring 303 (the surface opposite to the camshaft 13). It is formed so as to be along the substantially radial direction.

Further, as shown in FIG. 11, the driven shaft member 307 has a diameter-enlarged portion formed on the outer periphery of the base portion that is abutted against the front end portion of the camshaft 13, and is formed on the outer peripheral surface on the front side of the enlarged-diameter portion. Three levers 309 projecting radially are integrally formed and coupled to the camshaft 13 by bolts 310 penetrating the shaft core portion.
The base end of each link 311 is pivotally connected to each lever 309 by a pin 312, and a columnar protrusion 313 slidably engaged with each radial groove 308 is integrally formed at the tip of each link 311. Is formed.

  Since each link 311 is connected to the driven shaft member 307 via the pin 312 in a state where the protruding portion 313 is engaged with the corresponding radial groove 308, the distal end side of the link 311 receives an external force and receives the radial groove. When displaced along 308, the drive ring 303 and the driven shaft member 307 are relatively rotated by the action of the link 311 by a direction and an angle corresponding to the displacement of the protrusion 313.

In addition, a housing hole 314 that opens to the front side in the axial direction is formed at the tip of each link 311, and the housing hole 314 has a spherical protrusion 316 a that engages with a spiral groove 315 (spiral guide) described later. An engagement pin 316 (rolling member) and a coil spring 317 that biases the engagement pin 316 forward (spiral groove 315 side) are accommodated.
In this embodiment, a movable guide portion that is displaceable in the radial direction is constituted by the protruding portion 313 at the tip of the link 311, the engaging pin 316, the coil spring 317, and the like.

On the other hand, an intermediate rotating body 318 having a disk-like flange wall 318 a is rotatably supported via a bearing 331 in front of the protruding position of the lever 309 of the driven shaft member 307.
The aforementioned spiral groove 315 having a semicircular cross section is formed on the rear surface side of the flange wall 318a of the intermediate rotating body 318, and the engagement pin 316 at the tip of each link 311 can freely roll in the spiral groove 315. Is engaged with the guide.

The spiral of the spiral groove 315 is formed so as to gradually reduce the diameter along the rotation direction of the drive ring 303.
Accordingly, in the state where the engagement pin 316 at the tip of each link 311 is engaged with the spiral groove 315, when the intermediate rotating body 318 rotates relative to the drive ring 303 in the delay direction, the tip of the link 311 becomes the radial groove 308. When the intermediate rotating body 318 is relatively displaced in the advancing direction, it is guided radially by the spiral shape of the spiral groove 315 and conversely moves in the radial direction.

The assembly angle operation mechanism 304 of this embodiment is constituted by the radial groove 308, the link 311, the protrusion 313, the engagement pin 316, the lever 309, the intermediate rotating body 318, the spiral groove 315, etc. of the drive ring 303 described above. Has been.
When the relative rotation operation force with respect to the camshaft 13 is input from the operation force applying means 305 to the intermediate rotating body 318, the assembly angle operation mechanism 304 receives the operation force from the spiral groove 315 and the engagement pin 316. The distal end of the link 311 is displaced in the radial direction through the engaging portion, and at this time, relative rotational force is transmitted to the drive link 303 and the driven shaft member 307 by the action of the link 311 and the lever 309.

  On the other hand, the operating force applying means 305 brakes the mainspring 319 for biasing the intermediate rotator 318 in the rotation direction of the drive ring 303 and the intermediate spring 318 for biasing in the direction opposite to the rotation direction of the drive ring 303. And a hysteresis brake 320 as a mechanism, and by appropriately controlling the braking force of the hysteresis brake 320 according to the operating state of the internal combustion engine, the intermediate rotating body 318 is rotated relative to the drive ring 303, Or the rotation position of both of them is maintained.

The spring spring 319 has an outer peripheral end coupled to a cylindrical member 321 integrally attached to the drive ring 303, while an inner peripheral end is coupled to a cylindrical base of the intermediate rotating body 318, and the whole is intermediate. The rotating body 318 is disposed in the space on the front side of the flange wall 318a.
On the other hand, the hysteresis brake 320 is restricted in rotation by a bottomed cylindrical hysteresis ring 323 attached to the front end portion of the intermediate rotating body 318 via a retainer plate 322, and a VTC cover (not shown) which is a non-rotating member. An electromagnetic coil 324 as a magnetic field control means attached in a state, and a coil yoke 325 which is a magnetic induction member for guiding the magnetism of the electromagnetic coil 324. The electromagnetic coil 324 is controlled by the ECU 114 according to the operating state of the engine. The energization is controlled.

As shown in FIG. 15, the hysteresis ring 323 is formed of a hysteresis material (semi-hard material) having a characteristic (magnetic hysteresis characteristic) in which magnetic flux force changes with a phase lag with respect to a change in an external magnetic field. The cylindrical wall 323a is subjected to a braking action by the coil yoke 325.
The entire coil yoke 325 is formed in a substantially cylindrical shape so as to surround the electromagnetic coil 324, and an inner peripheral surface thereof is rotatably supported by the tip end portion of the driven shaft member 307 via a bearing 328.

A pair of circumferential facing surfaces 326 and 327 are formed on the rear surface side (intermediate rotating body 318 side) of the coil yoke 325 so that the magnetic input / output portions face each other with a cylindrical gap.
Further, as shown in FIG. 13, a plurality of concavities and convexities are continuously formed along the circumferential direction on both facing surfaces 326 and 327 of the coil yoke 325, and the convex portions 326a and 327a of these concavities and convexities are formed as magnetic poles. (Magnetic field generator).

And the convex part 326a of one opposing surface 326 and the convex part 327a of the other opposing surface 327 are alternately arrange | positioned in the circumferential direction, and the convex parts 326a and 327a which the opposing surfaces 326 and 327 mutually adjoin are all the circumferential direction. It is shifted to.
Accordingly, a magnetic field having a direction inclined in the circumferential direction as shown in FIG. 16 is generated between the convex portions 326 a and 327 a adjacent to each other on the opposing surfaces 326 and 327 by the excitation of the electromagnetic coil 24.

A cylindrical wall 323a of the hysteresis ring 323 is interposed in a non-contact state in the gap between the opposing surfaces 326 and 327.
Here, the operating principle of the hysteresis brake 320 will be described with reference to FIG.
17A shows a state in which a magnetic field is first applied to the hysteresis ring 323 (hysteresis material), and FIG. 17B shows a state in which the hysteresis ring 323 is displaced (rotated) from the state of FIG. Indicates the state.

17A, the direction of the magnetic field between the opposing surfaces 326 and 327 of the coil yoke 325 (the direction of the magnetic field from the convex portion 327a of the opposing surface 27 toward the convex portion 327a of the other opposing surface 326) is met. Thus, a magnetic flux flows in the hysteresis ring 323.
When the hysteresis ring 323 is moved in response to the external force F as shown in FIG. 17B from this state, the hysteresis ring 323 is displaced in the external magnetic field. At this time, the magnetic flux inside the hysteresis ring 323 is phase-shifted. There is a delay, and the direction of the magnetic flux inside the hysteresis ring 323 is deviated (tilted) with respect to the direction of the magnetic field between the opposing surfaces 326 and 327.

  Accordingly, the flow of magnetic flux (magnetic lines) entering the hysteresis ring 323 from the convex portion 327a of the opposing surface 327 and the flow of magnetic flux (magnetic lines) from the hysteresis ring 323 toward the convex portion 326a of the other opposing surface 326 are distorted. An attractive force that corrects the distortion of the magnetic flux acts between the opposing surfaces 326 and 327 and the hysteresis ring 323, and the attractive force acts as a drag force F ′ that brakes the hysteresis ring 323.

  When the hysteresis ring 323 is displaced in the magnetic field between the opposing surfaces 326 and 327 as described above, the hysteresis brake 320 generates a braking force due to the deviation of the direction of the magnetic flux inside the hysteresis ring 323 and the direction of the magnetic field. However, the braking force depends on the strength of the magnetic field, that is, the magnitude of the excitation current of the electromagnetic coil 324, regardless of the rotational speed of the hysteresis ring 323 (relative speed between the opposed surfaces 326 and 327 and the hysteresis ring 323). It becomes a constant value approximately proportional to.

  The VTC mechanism 201 according to the present embodiment is configured as described above. When the excitation of the electromagnetic coil 324 of the hysteresis brake 320 is turned off, the intermediate rotating body 318 is moved against the drive ring 303 by the urging force of the mainspring spring 319. The maximum rotation angle in the engine rotation direction, and the engagement pin 316 is regulated at a position where it abuts against the outer peripheral side end face 315a of the spiral groove 315, and this position can be changed on the mechanism of the VTC mechanism 201. (See FIG. 12).

  When the excitation of the electromagnetic coil 324 is turned on from this state, a braking force against the force of the mainspring spring 319 is applied to the intermediate rotating body 318, and the intermediate rotating body 318 rotates in the reverse direction with respect to the drive ring 303, As a result, the engaging pin 316 at the tip of the link 311 is guided into the spiral groove 315, whereby the tip of the link 311 is displaced along the radial groove 308, and the drive ring 303 and the driven shaft member 307 are acted upon by the link 11. The assembly angle is changed to the advance side.

When the exciting current of the electromagnetic coil 324 is increased to increase the braking force, the engagement pin 316 is finally regulated at a position where it abuts against the inner peripheral side end surface 315b of the spiral groove 315, and this position is the VTC mechanism. This is the most advanced position of the rotational phase that can be changed on the mechanism 201 (see FIG. 14).
When the exciting current of the electromagnetic coil 324 is reduced from this state and the braking force is reduced, the intermediate rotating body 318 is rotated back in the forward direction by the urging force of the mainspring spring 319 and is linked by the induction of the engaging pin 316 by the spiral groove 315. 311 swings in the opposite direction, and the assembly angle of the drive ring 303 and the driven shaft member 307 is changed to the retard side.

  As described above, the rotational phase of the camshaft 13 with respect to the crankshaft 120 (the central phase of the operating angle of the intake valve 105) that is varied by the VTC mechanism 201 controls the excitation current value of the electromagnetic coil 324 and the hysteresis brake 320. It is arbitrarily changed by controlling the braking force, and the phase can be maintained by the balance between the force of the mainspring spring 319 and the braking force of the hysteresis brake 320.

The ECU 114 calculates the advance angle target of the rotation phase in the VTC mechanism 201, and feedback-controls the excitation current value of the electromagnetic coil 324 so that the actual rotation phase matches the advance angle target.
As described above, the lift amount (operating angle) and valve timing of the intake valve can be controlled with high accuracy by the VEL mechanism 112 and the VTC mechanism 201.

  By the way, the VEL mechanism 112 receives a reaction force from the valve spring when the intake valve 105 is lifted, and acts as a reaction torque on the control shaft 16. That is, the DC servo motor 121 increases the lift amount (operating angle) while rotating the control shaft 16 against the reaction torque. Although the magnitude of the reaction torque increases or decreases depending on the lift amount, the direction of the torque does not change. Therefore, when the operation of the DC servo motor 121 is stopped, the reaction force torque continues to act in the direction of decreasing the lift amount. Furthermore, the minimum lift amount (minimum operating angle) characteristic is changed.

Therefore, when the operation of the VEL mechanism 112 is stopped due to a failure of the DC servo motor 121 or its drive circuit or the like, a fail-safe function that automatically becomes the minimum lift amount characteristic (reference characteristic) and reduces the intake air amount is provided. It comes to work.
However, as described above, if the camshaft 13 is fixed due to foreign matter biting or the like, the fail-safe function does not work even if the VEL mechanism 112 stops driving due to a failure of the DC servo motor 121, and the intake valve 105 may be maintained at a high lift amount characteristic, and the intake air amount may become too large (the engine output is too large).

In addition, if the engine output is reduced by another fail-safe process after detecting the above situation, the delay becomes large, and a good fail-safe function cannot be obtained.
Therefore, in the present invention, the fail safe function is diagnosed in advance when the drive of the VEL mechanism 112 is stopped under predetermined operating conditions, so that the presence or absence of the failure of the fail safe function is detected in advance.

The fail safe function diagnosis process when the driving of the VEL mechanism 112 is stopped will be described below.
FIG. 18 shows a main flow of the diagnosis. The control cycle is set at regular intervals (10 ms).
In step S1, the success or failure of the diagnosis permission condition is determined based on the operating state of the engine.
When it is determined in step S1 that the diagnosis permission condition is satisfied, the process proceeds to step S2, and the driving of the VEL mechanism 112 is forcibly stopped.

In step S3, after the drive of the VEL mechanism 112 is stopped, a change speed VLRATE when the intake valve opening characteristic changes to the minimum lift amount characteristic is calculated.
In step S4, a predetermined value NGLVL (criteria) for diagnosis determination is calculated.
In step S5, the change speed VLRATE is compared with a predetermined value NGLVL for diagnosis.

FIG. 19 shows a detailed flow of a routine for determining success or failure of the diagnosis permission condition in step S1 of FIG.
In step S11, the previous value of the flag fDGNGO that is set (set to 1) when the diagnosis permission condition is satisfied is set as fDGNGOz.
In step S12, it is determined whether the flag fVLACTEND set at the end of the diagnosis is 0, that is, before the diagnosis ends.

If it is determined in step S12 that fVLACTEND is 1 and the diagnosis is completed, it is not necessary to perform further diagnosis. Therefore, the process proceeds to step S19, and the fDGGNO is set to 0, that is, a value that does not permit the diagnosis. To do.
When fVLACTEND is 0 in step S12 and it is determined that the diagnosis is not completed, the process proceeds to step S13, and it is determined whether the fuel cut is in progress. When it is determined that the fuel cut is not in progress, the diagnosis is not permitted. Therefore, the process proceeds to step S19 to perform the above processing. When it is determined that the fuel cut is in progress, the basic diagnosis permission condition is satisfied. The process proceeds to step S14.

In step S14, it is determined whether the value of fDGNGOz is 0, that is, immediately after the basic diagnosis permission condition is established from the prohibition of diagnosis (first time). move on.
In step S15, it is determined whether the current engine speed Ne is equal to or higher than a predetermined value (for example, 3000 rpm). This is to ensure a sufficient diagnosis time until the fuel recovery (resumption of fuel supply) rotational speed is reached.

  When it is determined in step S15 that the engine rotation speed Ne is equal to or greater than a predetermined value, the process proceeds to step S16, and it is determined whether the actual rotation angle REVEL of the VEL mechanism 112 is equal to or greater than a predetermined value (for example, 30 degrees). This is because, when the rotation angle at the start of diagnosis is already small, the operation sensitivity of the VEL mechanism 112 for diagnosis cannot be obtained, so that an initial rotation angle at which good operation sensitivity can be obtained is secured.

When it is determined in step S16 that the actual rotation angle REVEL is 30 degrees or more, since the diagnosis permission condition is finally satisfied, the process proceeds to step S17, fDGGNO is set to 1, and diagnosis is permitted.
As described above, when the diagnosis is permitted, the determination in step S14 is NO in the next flow, and the process proceeds to step S18, in which it is determined whether the engine rotational speed Ne is equal to or higher than a predetermined value 1500 rpm for determining the end of diagnosis. If it is 1500 rpm or more, the diagnosis is continued, but if it falls below 1500 rpm, the process proceeds to step S19 to set fDGNGO to 0 and the diagnosis is terminated.

FIG. 20 shows details of a routine for forcibly stopping the driving of the VEL mechanism 112 in step S2 of FIG.
In step S <b> 21, it is determined whether diagnosis is permitted based on whether fDGNGOz is “1”.
When it is determined in step S21 that the diagnosis is permitted, the process proceeds to step S22, the energization to the DC servo motor 121 is turned off, and the drive of the VEL mechanism 112 is forcibly stopped.

If it is determined in step S21 that the diagnosis is not permitted, the process proceeds to step S23, the energization of the DC servo motor 121 is turned on, and the drive of the VEL mechanism 112 is restored.
FIG. 21 shows the details of a routine for calculating the changing speed when the opening characteristic of the intake valve changes to the minimum lift amount characteristic when the driving of the VEL mechanism 112 is stopped in step S3 of FIG. In the embodiment, instead of directly calculating the change speed of the opening characteristic of the intake valve, it is indirectly calculated from the change speed of the rotation angle of the VEL mechanism 112 corresponding to the open characteristic.

In step S31, it is determined whether or not the diagnosis is permitted depending on whether fDGNGO is 1. Only when the diagnosis is permitted, the process proceeds to step S32 and thereafter, and the change speed is calculated. Is terminated and calculation is prohibited.
In step S32, the diagnosis permission time DGNTIM is calculated (since it is 10 ms JOB, the diagnosis permission time is accumulated by 0, 01 sec).

In step S33, it is determined whether or not the previous value fDGNGOz was 0, that is, whether or not the current process is permitted from diagnosis prohibition, and if it is the first time, calculation parameters are initialized in steps S34 and S35.
Specifically, in step S34, the current actual rotation angle REVEL is set as the actual rotation angle DGVELINT at the time of diagnosis permission, and in step S35, the diagnosis permission time DGNTIM is cleared.

Thereafter, the determination in step S33 is NO in the next flow, and the process proceeds to step S36. Using the actual rotation angle DGVELINT and diagnosis permission time DGNTIM when the diagnosis is permitted, the actual rotation angle change speed VLRATE ( Degree / sec), that is, the change speed of the intake valve opening characteristic.
VLRATE = (DGVELINT−RAVEL) / DGNTIM
FIG. 22 shows details of a routine for calculating a predetermined value (criteria) for diagnosis in step S4 of FIG.

In step S41, based on the engine speed Ne and the engine temperature (cooling water temperature, lubricating oil temperature, etc.), a predetermined value NGLVL to be compared with the change speed VLRATE is calculated with reference to a map.
Here, the higher the engine rotation speed Ne at the time of diagnosis, the shorter the reaction torque torque fluctuation period, and the easier it is to move, and the higher the engine temperature, the faster the change speed. The predetermined value NGLVL is set to increase.

FIG. 23 shows details of a routine for making a diagnosis by comparing the change speed with a predetermined value in step S5.
In step S51, it is determined whether the diagnosis is permitted depending on whether fDGNGO is 1. Only when the diagnosis is permitted, the process proceeds to step S52 and after, and if not permitted, the routine is terminated. Prohibit diagnosis.

In step S52, based on the diagnosis permission time DGNTIM, it is determined whether a predetermined time (200 ms) has elapsed since the diagnosis was permitted, and the diagnosis is not executed before the time has elapsed.
After it is determined that the predetermined time has elapsed, the process proceeds to step S53, and the change speed VLRATE is compared with a predetermined value NGLVL.
When it is determined that the change speed VLRATE is equal to or higher than the predetermined value NGLVL, it is determined that the fail-safe function having the minimum lift amount characteristic when the driving of the VEL mechanism 112 is stopped normally. fVLACT is set to 0, and the diagnosis result is normal (OK).

  On the other hand, when it is determined that the change speed VLRATE is less than the predetermined value NGLVL, an abnormality such as the camshaft is stuck due to a foreign object biting or the like, and the minimum lift amount characteristic is maintained even when the drive of the VEL mechanism 112 is stopped. Therefore, the process proceeds to step S54 where the diagnosis flag fVLACT is set to 1 and the diagnosis result is abnormal (NG). The diagnosis result (fVLACT = 1) indicating that there is an abnormality stores information in a backup RAM, EEPROM, or the like, and further performs a process of turning on an engine check lamp and notifying the driver of the failure status.

In step S55, since the diagnosis is completed, the flag fVLACTEND is set to 1.
In this way, since the fail-safe function is diagnosed in advance when the driving of the VEL mechanism 112 is stopped, another fail-safe control as will be described later is performed to obtain a good fail-safe function when an abnormality occurs. Can do.

In addition, by making a diagnosis based on the speed of change to the minimum lift amount characteristic (reference characteristic), by diagnosing an abnormality when the change to the reference characteristic is delayed, another fail-safe control before reaching a complete failure It is possible to ensure a good fail-safe function by switching to.
In the present embodiment, since the diagnosis is performed during the fuel cut, the influence on the operation can be avoided.

FIG. 24 shows a detailed flow of a routine for determining success or failure of a diagnosis permission condition in the second embodiment that permits diagnosis under a high load condition.
In steps S61 and S62, the previous value of fDGNGO is set as fDGNGOz in the same manner as in steps S11 and S12 of FIG. 19, and it is determined whether or not the diagnosis is completed based on the value of fVLACTEND. Proceeding to S70, fDGGNO is set to 0.

When it is determined that the diagnosis has not been completed, the process proceeds to step S63, where it is determined whether the current engine speed Ne is a predetermined value 1500 rpm or more that does not generate an engine stall or the like and has little influence on drivability even if diagnosis is performed. If it is less than the predetermined value, the process proceeds to step S70 and no diagnosis is performed.
When it is determined that the engine rotational speed Ne is equal to or higher than the predetermined value, the process proceeds to step S64, where it is determined whether the accelerator opening APO is in a high load region where the predetermined value is 40 degrees or higher. The process proceeds to step S70 and no diagnosis is performed.

When it is determined that the accelerator opening APO is in a high load state that is equal to or greater than the predetermined value, the process proceeds to step S65, and whether the rotation angle target value TGVEL of the VEL mechanism 112 is equal to or greater than the predetermined value 50 degrees, that is, at high load. Further, it is determined whether or not the amount of change in the intake air amount (torque) with respect to the change in the rotation angle is small.
If it is determined that the rotation angle target value TGVEL is equal to or greater than the predetermined value, the process proceeds to step S66, whether the value of fDGNGOz is 0, that is, immediately after the basic diagnosis permission condition is established from the diagnosis prohibition (first time). If it is determined immediately after that, the process proceeds to step S67.

In step S67, it is determined whether or not the actual rotation angle REVEL is equal to or greater than the predetermined value 50 degrees, and if it is equal to or greater than the predetermined value, the diagnosis permission condition is finally satisfied, so the process proceeds to step S68 and fDGNGO is set. Set to 1 to allow diagnosis.
As described above, when the diagnosis is permitted, the determination in step S66 is NO in the next flow, and the process proceeds to step S69, and whether or not the actual rotation angle REVER is equal to or greater than the predetermined value 30 degrees for the diagnosis end determination. If it is determined that the angle is 30 degrees or more, the diagnosis is continued. If the angle is less than 30 degrees, the process proceeds to step S70, where fDGNGO is set to 0 and the diagnosis is terminated.

In this way, it is possible to make a good diagnosis under a high load condition in which the torque drop is small even if the diagnosis is made.
FIG. 25 shows a detailed flow of a routine for determining success or failure of a diagnosis permission condition in the third embodiment that permits diagnosis when an engine stall state occurs.
In steps S81 and S82, the previous value of fDGNGO is set as fDGNGOz in the same manner as in steps S11 and S12 in FIG. 19, and it is determined whether or not the diagnosis is completed based on the value of fVLACTEND. Proceeding to S88, fDGGNO is set to 0.

In step S83, it is determined whether the signal IGNSW of the ignition switch is 0, that is, whether the ignition switch is OFF. If it is determined OFF, the process proceeds to step S84.
In step S84, it is determined whether or not the engine rotational speed Ne is equal to or higher than a predetermined value (2000 rpm). When the engine rotational speed Ne is equal to or higher than the predetermined value, that is, it is determined that the engine is stalled while the engine is being stopped. If it is determined that the basic diagnosis permission condition is satisfied, the process proceeds to step S85.

In step S85, it is determined whether the value of fDGNGOz is 0, that is, immediately after switching from the diagnosis prohibition to the basic diagnosis permission condition being established (first time). move on.
In step S86, it is determined whether the actual rotation angle REVEL is equal to or greater than a predetermined value (30 degrees) that can ensure diagnostic sensitivity. If it is equal to or greater than the predetermined value, it is determined that the diagnosis permission condition is finally satisfied, and the process proceeds to step S87. Go ahead and set fDGNGO to 1 to allow diagnosis.

When any of the conditions in steps S82 to S84 is not satisfied, the process proceeds to step S88, fDGGNO is set to 0, and the diagnosis is terminated.
In this way, the diagnosis can be performed in an engine stall state that does not affect the diagnosis.
Of course, the diagnosis may be permitted when any (at least one) of the first to third diagnosis permission conditions is satisfied.

Next, fail-safe control when it is determined as abnormal (NG) by the above diagnosis will be described.
FIG. 26 shows control blocks of the VEL mechanism 112 and the VTC mechanism 201.
In the normal control, the target rotation angle TGVEL0 of the VEL mechanism 112 and the target advance angle value TGVTC0 of the VTC mechanism 201 are set with reference to each map based on the target volume flow ratio TQH0ST and the engine rotation speed Ne, respectively. (S101, S102).

Here, the target volume flow ratio TQH0ST is a value substantially corresponding to the target value of the cylinder volume efficiency, and the required intake air amount Q corresponding to the target torque set based on the accelerator opening APO, the engine speed Ne, and the like. Is sequentially divided by the engine rotational speed Ne and the displacement (total cylinder volume) VOL # [TQH0ST = Q / (Ne · VOL #)].
On the other hand, the target rotation angle TGVEL when it is diagnosed that there is an abnormality in the fail safe function when the drive of the VEL mechanism 112 is stopped is set as a predetermined default value TGVELD (for example, 40 degrees) corresponding to the abnormality. Similarly, the target advance value TGVTC is set to 0 (the most retarded value) as the default value TGVTCD (S105).

The signal switching unit (S107) receives the target rotation angle TGVEL and target advance value TGVTC for normal control, the default value TGVELD and default value TGVTCD when the abnormality is diagnosed, and the diagnosis flag fVLACT. .
In the figure, for the sake of simplicity, the target rotation angle TGVEL0 and the target advance angle value TGVTC0, and the default value TGVELD and the default value TGVTCD are shown as being combined into one signal and input to the signal switching unit. (S103, S106).

  In the normal control in which the value of the diagnosis flag fVLACT is 0, the target rotation angle TGVEL0 and the target advance angle value TGVTC0 are selected. The value TGVTCD is selected, and the selected final target rotation angle TGVEL and target advance value TGVTC are output.

In the figure, one signal line output from the signal switching unit is shown again as two signal lines (S108).
Next, FIG. 27 shows a control block of the electronic control throttle 104.
Refer to the characteristic conversion table for the target volume flow ratio TQH0ST and the state quantity [= A / (Ne · VOL #)] obtained by sequentially dividing the throttle opening area A by the engine speed Ne and the displacement (total cylinder volume) VOL #. (S201). This table is set as a conversion characteristic in a state (standard valve characteristic) in which the lift amount (operating angle) and valve timing of the intake valve are fixed to predetermined values.

The converted value is sequentially multiplied by the displacement VOL # and the engine rotational speed Ne to calculate the throttle opening area TVOAA at which the target volume flow ratio TQH0ST is obtained in the standard valve characteristics (S202 to S203).
In contrast to the throttle opening area TVOAA with the standard valve characteristic, during normal control, the throttle opening area depends on the lift amount and valve timing (variable valve characteristic) of the intake valve variably controlled by the VEL mechanism 112 and the VTC mechanism 201. Is corrected to obtain the target volume flow ratio TQH0ST.

  Specifically, based on the target volume flow ratio TQH0ST and the engine speed Ne, the map shows the ratio Pm0 / Pa between the intake pressure (manifold pressure) Pm0 and the atmospheric pressure Pa downstream of the throttle valve 103a in the standard valve characteristics. Based on the pressure ratio Pm0 / Pa, the flow rate coefficient KAP0 with the standard valve characteristic correlated with the flow rate (flow velocity) per unit area is calculated based on the pressure ratio Pm0 / Pa (S205).

On the other hand, the ratio Pm1 / Pa between the intake pressure Pm1 downstream of the throttle valve 103a and the atmospheric pressure Pa in the variable valve characteristic to be variably controlled is calculated by referring to a map or the like (S206), and based on the pressure ratio Pm1 / Pa. The flow coefficient KAP1 with the variable valve characteristic is calculated with reference to the table (S207).
The method for calculating the pressure ratio Pm1 / Pa in the variable valve characteristic is described in Japanese Patent Application Laid-Open No. 2003-184587, and detailed description thereof is omitted, but the intake valve of the variable valve characteristic is compared with the standard valve characteristic. When the effective opening area is small, the pressure on the upstream side of the intake valve relatively increases, and the pressure ratio Pm1 / Pa becomes larger than the pressure ratio Pm0 / Pa, and as a result, compared with the flow coefficient KAP0 in the standard valve characteristics. As a result, the flow coefficient KAP1 in the variable valve characteristic is reduced.

The pressure ratio Pm0 / Pa in the standard valve characteristic is divided by the pressure ratio Pm1 / Pa in the variable valve characteristic, and the divided value is used as a correction coefficient KAVEL corresponding to the valve characteristic of the intake valve of the throttle opening area. Set as KAVEL0 (S208).
On the other hand, when it is diagnosed that there is an abnormality in the fail safe function when the drive of the VEL mechanism 112 is stopped, the correction coefficient KAVEL = 1 is set to prohibit the correction of the throttle opening area according to the valve characteristics of the intake valve. Fixed and set (S209).

The signal switching unit (S210) receives the value KAVEL0 in the variable valve characteristic of the correction coefficient KAVEL, the fixed value 1 when the abnormality is diagnosed, and the diagnosis flag fVLACT.
In the normal control where the value of the diagnosis flag fVLACT is 0, the KAVEL0 is selected. When the diagnosis flag fVLACT is diagnosed as 1 abnormal, the fixed value 1 is selected, and each selected value is Is output as a typical correction coefficient KAVEL.

By multiplying the throttle opening area TVOAA by the correction coefficient KAVEL calculated as described above, a final target throttle opening area AA is calculated (S211), and the target throttle opening area AA is calculated by a conversion table. The target throttle opening degree TGTVO is converted and output (S212).
Here, the effective opening area in the intake valve characteristic (default value TGVELD = 40 degrees, default value TGVTCD = 0 (most retarded angle value)) when the abnormality is diagnosed is smaller than the effective opening area in the standard valve characteristic. If this is set, the target throttle opening under the same conditions will be smaller than during normal control, and the maximum opening of the throttle valve will be reduced to limit the maximum engine output, ensuring a good fail-safe function. it can. If the default value TGVELD and the default value TGVTCD are set to match the standard valve characteristics, the target intake air amount (target volume flow ratio) can be obtained only with the throttle valve with the intake valve characteristics fixed to the standard valve characteristics. TQH0ST) will be switched to control.

  In the above embodiment, the diagnosis of the failure of the fail-safe function when the drive of the VEL mechanism 112 is stopped is shown. However, the VTC mechanism 201 which is another variable valve mechanism is also used as described above when the drive is stopped. Has the same problem that the fail safe function does not operate normally due to camshaft fixing or the like.

Therefore, the VTC mechanism 201 can be forced to stop under a predetermined operating condition to make a diagnosis, and when failing is diagnosed, another fail-safe control can be executed.
In this embodiment, when the driving of the VTC mechanism 201 is stopped, the change speed when the valve timing changes to the most retarded value may be compared with a predetermined value for diagnosis. Accordingly, in the diagnosis flowchart of the VEL mechanism 112, the target advance angle value TGVTC and the actual VTC are compared with the predetermined value in the step S for comparing the target rotation angle TGVEL and the actual rotation angle REVEL with the predetermined value, and The magnitude of the predetermined value (advance value) to be compared in the diagnosis of the VTC mechanism 201 may be set in proportion to the magnitude of the predetermined value (rotation angle) to be compared in the diagnosis of the VEL mechanism 112.

Further, when an abnormality is diagnosed in the fail-safe function at the time of stopping the driving of the VTC mechanism 201, the fail-safe control by the throttle control shown in FIGS. 26 and 27 may be performed.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) In the variable valve mechanism diagnostic apparatus according to any one of claims 1 to 4,
Conditions for permitting diagnosis by the diagnosis permission determining means include during fuel cut.

According to such a configuration, since the diagnosis is performed during the fuel cut, the influence on the operation can be avoided.
(B) In the diagnostic apparatus for a variable valve mechanism according to any one of claims 1 to 4 or (a) above,
Conditions for permitting diagnosis by the diagnosis permission determining means include when an engine stop request is made, and the diagnosis means makes a diagnosis between the engine stop request and the engine rotation stop.

According to such a configuration, diagnosis can be performed when an engine stall has occurred without affecting driving.
(C) In the diagnostic apparatus for a variable valve mechanism according to any one of claims 1 to 4, or any one of (a) and (b) above,
The diagnosis means makes a diagnosis by comparing the change speed with a predetermined value set according to the engine temperature.

According to such a configuration, since the friction during operation of the variable valve mechanism changes according to the engine temperature and the speed of change changes, by setting a predetermined value for diagnosis (determination) according to the engine temperature, the engine Highly accurate diagnosis can be performed without being affected by temperature.
(D) In the diagnostic apparatus for a variable valve mechanism according to any one of claims 1 to 4 or any one of (a), (b), and (c) above,
The diagnosis means makes a diagnosis by comparing the change speed with a predetermined value set according to the engine rotation speed.

According to such a configuration, when the engine rotation speed increases, the fluctuation period of the reaction torque received by the variable valve mechanism is shortened and the change speed increases, so a predetermined value for diagnosis (determination) is set according to the engine temperature. Thus, highly accurate diagnosis can be performed without being influenced by the engine speed.
(E) In the diagnostic apparatus for a variable valve mechanism according to any one of claims 1 to 4, or (a), (b), (c), (d) above,
The variable valve mechanism is a variable valve timing control (VTC) mechanism having a function of changing the valve timing of the intake valve so that the valve timing becomes the most retarded value when driving is stopped.

  According to such a configuration, when the drive of the VTC mechanism is stopped as in the case of the VEL mechanism, an abnormality of the failsafe function that becomes the most retarded angle value can be diagnosed during operation, and when the abnormality is diagnosed, another failsafe control is performed. It can be performed.

1 is a system configuration diagram of an internal combustion engine in an embodiment. Sectional drawing (AA sectional drawing of FIG. 3) which shows a VEL (Variable valve Event and Lift) mechanism. The side view of the said VEL mechanism. The top view of the said VEL mechanism. The perspective view which shows the eccentric cam used for the said VEL mechanism. Sectional drawing which shows the effect | action at the time of the low lift of the said VEL mechanism (BB sectional drawing of FIG. 3). Sectional drawing which shows the effect | action at the time of the high lift of the said VEL mechanism (BB sectional drawing of FIG. 3). The valve lift characteristic view corresponding to the base end surface and cam surface of the swing cam in the VEL mechanism. FIG. 6 is a characteristic diagram of valve timing and valve lift of the VEL mechanism. The perspective view which shows the rotational drive mechanism of the control shaft in the said VEL mechanism. Sectional drawing which shows a VTC (Variable valve Timing Control) mechanism. Sectional drawing which follows the AA line of FIG. Sectional drawing which follows the BB line of FIG. Sectional drawing similar to FIG. 12 which shows the operating state of the said VTC mechanism. The graph which shows the magnetic flux density-magnetic field characteristic of a hysteresis material. FIG. 14 is a partially enlarged sectional view of FIG. 13. It is the schematic diagram which expand | deployed the components of FIG. 16 linearly, and is a figure which shows the flow of the magnetic flux in the initial state (a) and when a hysteresis ring rotates (b). The main flowchart of the diagnosis of a fail safe function at the time of the drive stop of the said VEL mechanism. The flowchart of the routine which determines the success or failure of a diagnosis permission condition in the said diagnosis. 7 is a flowchart of a routine for forcibly stopping driving of the VEL mechanism in the diagnosis. In the above diagnosis, a flowchart of a routine for calculating a change speed when the opening characteristic of the intake valve changes to the minimum lift amount characteristic when the driving of the VEL mechanism is stopped. The flowchart of the routine which calculates the predetermined value (criteria) of a diagnosis in the said diagnosis. 7 is a flowchart of a routine for performing a diagnosis by comparing a change speed with a predetermined value in the diagnosis. The flowchart of the routine which determines the success or failure of the diagnosis permission condition in 2nd Embodiment which permits a diagnosis on high load conditions.

The figure which shows the mode of the change of the various states when the control at the time of deceleration in 1st Embodiment is performed.
The flowchart of the routine which determines the success or failure of the diagnosis permission conditions in 3rd Embodiment which permits a diagnosis when it becomes an engine stall state. The control block diagram which shows the fail safe control of a VEL mechanism and a VTC mechanism when the said diagnostic result is abnormal. The control block diagram which shows the fail safe control of an electronically controlled throttle when the said diagnostic result is abnormal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 13 ... Camshaft, 16 ... Control shaft, 101 ... Internal combustion engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 112 ... VEL mechanism, 114 ... Engine control unit (ECU), 117 ... Crank angle sensor, 120 ... Crankshaft 121 ... DC servo motor, 127 ... angle sensor, 201 ... VTC mechanism, 202 ... cam angle sensor

Claims (4)

A variable valve mechanism diagnostic device configured to vary an opening characteristic of an intake valve or an exhaust valve of an internal combustion engine and to have the opening characteristic become a reference characteristic when supply of driving force is stopped,
Diagnosis permission determination means for performing diagnosis permission determination based on the engine operating state;
Driving stop means for forcibly stopping the supply of driving force to the variable valve mechanism when the diagnosis is permitted;
A change speed calculating means for calculating a change speed when the open characteristic changes to the reference characteristic by stopping the driving force supply to the variable valve mechanism by the drive stop means;
Diagnostic means for diagnosing whether there is an abnormality in the function whose opening characteristic becomes a reference characteristic when the variable valve mechanism is stopped based on the calculated change speed;
A diagnostic apparatus for a variable valve mechanism, comprising:   The diagnostic apparatus for a variable valve mechanism according to claim 1, wherein when an abnormality is diagnosed by the diagnostic means, an abnormality alarm is transmitted or stored.   3. The throttle valve of the intake valve upstream of the intake valve upstream of the intake valve is controlled when the variable valve mechanism for the intake valve is diagnosed as abnormal by the diagnosis unit. Diagnostic device for variable valve mechanism.   The variable valve mechanism is a mechanism for changing at least one of a valve lift or an operating angle of an intake valve, and a condition for permitting diagnosis by the diagnosis permission determining unit is that the change in the valve lift or the operating angle is The diagnostic apparatus for a variable valve mechanism according to any one of claims 1 to 3, further comprising a high load region in which a change in the intake air amount is small.

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