JP2003222035A - Diagnosis device of variable valve timing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnosis device diagnoses abnormality such as wearing in an electromagnetic brake without affecting the operability, and with sufficient frequency in a variable valve timing mechanism for displacing a rotational phase of a camshaft into a retardation angle direction and a timing angle direction with braking force by means of two electromagnetic brakes. <P>SOLUTION: In a stable state of the rotational phase, two electromagnetic brakes are operated at the same time with such a control signal that a torque of the timing angle direction and a torque of the retardant angle direction become same. When the rotational phase changes over the predetermined level with the simultaneous operation, the abnormality of the electromagnetic brake is determined. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diagnostic device for a variable valve timing mechanism that changes the valve timing of an engine valve (intake / exhaust valve).

[0002]

2. Description of the Related Art Conventionally, as a variable valve timing mechanism, an opening / closing timing of an engine valve is changed to an advance side and a retard side with respect to a crank angle by changing a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine. It is known to have a configuration that allows it.

For example, in the variable valve timing mechanism disclosed in Japanese Unexamined Patent Publication No. 2001-041013, a drive rotary body to which rotation is transmitted from a crankshaft of an internal combustion engine and a driven rotary body on a camshaft side are attached at an assembly angle. A configuration in which the valve timing of the engine valve is changed by coaxially connecting via an adjusting mechanism, and by changing the assembling angle of the drive rotating body and the driven rotating body by the assembling angle adjusting mechanism, In the assembly angle adjusting mechanism, one end of the rotating portion is rotatably connected to one of the driving rotating body and the driven rotating body, and the other sliding portion is provided at the other of the driving rotating body and the driven rotating body. A link arm slidably connected in the radial direction by a radial guide, the position of the rotating portion is relatively displaced in the circumferential direction as the sliding portion moves in the radial direction, and the rotating body and the driven rotating body are moved. The relative rotation angle of the guide plate, which is configured so that the assembling angle with the rotating body is relatively changed, and on which the spiral guide engaged with the sliding portion of the link arm is formed, is controlled by the braking force of the electromagnetic brake. As a result, the slide portion is displaced in the radial direction, and thereby the valve timing is advanced / retarded.

Hereinafter, the variable valve timing mechanism provided with the assembly angle adjusting mechanism having the above construction will be referred to as a spiral radial link type.

[0005]

By the way, in the variable valve timing mechanism for controlling the retard angle / advance angle by the electromagnetic brake as described above, the friction surface of the electromagnetic brake is worn, the coil current is reduced, and the friction in the brake operation is increased. When an abnormality such as an increase occurs, problems occur such as a slow control response and the inability to change the valve timing.

In the spiral radial link type variable valve timing mechanism disclosed in Japanese Patent Laid-Open No. 2001-041013, since the guide plate is biased in the retard direction of the valve timing by the spring, the electromagnetic brake is used. When turned off, the spring is returned to the most retarded position by the urging force of the mainspring. However, as in Japanese Patent Application No. 2001-319908 previously filed by the applicant, two electromagnetic brakes are used to advance and When controlling in the retard direction, it may not be possible to return the valve timing to the most retarded position due to wear of the electromagnetic brake, etc., so wear progresses before the control becomes uncontrollable. It is desirable to judge.

Here, a method of diagnosing an abnormality such as wear of the electromagnetic brake from the response of the rotation phase control is conceivable.
With such a diagnostic method, it is difficult to secure a sufficient opportunity for diagnosis because the diagnosis can be performed only when the valve timing is changed, and the valve timing is forcibly changed to secure the diagnosis frequency. Then, there is a problem that the drivability may be adversely affected by the deviation from the required valve timing.

Therefore, in the variable valve timing mechanism of the present invention in which the two electromagnetic brakes control the advancing direction and the retarding direction, a sufficient opportunity for diagnosis can be secured, and the drivability is not adversely affected. An object of the present invention is to provide a diagnostic device that can diagnose abnormalities such as wear of an electromagnetic brake.

[0009]

Therefore, according to the invention of claim 1, the rotation phase of the camshaft with respect to the crankshaft of the internal combustion engine is changed in the advance direction and the retard direction by the braking force of the two electromagnetic brakes. In a variable valve timing mechanism that changes the valve timing of an engine valve, the two electromagnetic brakes are forcibly and simultaneously actuated, and based on the difference in torque generated in the simultaneous actuation state,
The configuration is such that the presence or absence of abnormality of the variable valve timing mechanism is diagnosed.

According to the above structure, the two electromagnetic brakes are forcibly operated simultaneously to generate the drive torque in the advance direction and the drive torque in the retard direction of the rotational phase at the same time.
Here, if an abnormality such as wear progresses on the other hand, a difference occurs between both drive torques. Therefore, the variable valve timing mechanism abnormality (wear,
Coil current drop, friction increase, etc.) are diagnosed.

According to a second aspect of the present invention, the presence or absence of abnormality of the variable valve timing mechanism is diagnosed based on the change in the rotational phase when the two electromagnetic brakes are forcibly operated simultaneously. . According to the above configuration, 2
Since the rotation phase changes due to the difference in drive torque between the two electromagnetic brakes, the occurrence of abnormality is diagnosed based on the change in rotation phase that occurs during simultaneous operation.

According to a third aspect of the present invention, the two electromagnetic brakes are simultaneously actuated based on a diagnostic control signal in which the drive torque in the advance direction and the drive torque in the retard direction by the two electromagnetic brakes are the same when normal. When the amount of change in the rotational phase at this time is equal to or greater than a predetermined value, the variable valve timing mechanism is determined to be abnormal. According to the above configuration, the rotation phase is actually normal when the diagnostic control signal is given when the drive torque in the advance direction and the drive torque in the retard direction are the same under normal conditions (without wear etc.). Does not change, but if an abnormality (wear etc.) occurs, a difference in drive torque will occur and the rotation phase will change. Therefore, based on whether the rotation phase changes more than a predetermined value,
Determine whether there is any abnormality (wear, etc.).

According to a fourth aspect of the present invention, the two electromagnetic brakes are simultaneously actuated on the basis of a diagnostic control signal in which the drive torque in the advance direction and the drive torque in the retard direction by the two electromagnetic brakes are the same when normal. When the change speed of the rotation phase at this time is equal to or higher than a predetermined value, the variable valve timing mechanism is determined to be abnormal. According to the above configuration, the rotation phase is actually normal when the diagnostic control signal is given when the drive torque in the advance direction and the drive torque in the retard direction are the same under normal conditions (without wear etc.). Does not change, but if an abnormality (wear etc.) occurs, a difference in driving torque will occur and the rotation phase will change. Therefore, based on whether the rotation phase changes at a predetermined speed or more, Determine whether there is any abnormality (wear, etc.).

According to a fifth aspect of the present invention, the diagnostic control signal is set according to the input torque from the camshaft side. According to the above configuration, when the torque acting in the direction of actually changing the rotation phase is affected by the input torque (reaction force) from the camshaft side, the diagnostic control signal is set according to the change of the input torque. hand,
If normal, it does not change the rotation phase, but gives a control signal that changes the rotation phase when an abnormality occurs.

According to a sixth aspect of the present invention, the diagnostic control signal is set according to the temperature characteristics of each of the two electromagnetic brakes. According to the above configuration, the drive current flowing through the coil changes depending on the coil temperature of the electromagnetic brake, and the diagnostic control signal is set in response to the change in the generated torque. A control signal for changing the rotation phase when an abnormality occurs is applied without changing it.

According to a seventh aspect of the present invention, the two electromagnetic brakes are forcibly actuated simultaneously, and the control signals of the respective electromagnetic brakes are feedback-controlled so that the rotation phase maintains a constant position, and the rotation is controlled. The configuration is such that the presence or absence of abnormality of the variable valve timing mechanism is diagnosed based on the difference between the control signals of the respective electromagnetic brakes when the phase is maintained at a constant position.

According to the above structure, when the rotational phase changes when two electromagnetic brakes are simultaneously operated, the control signal of the electromagnetic brake is feedback-controlled so as to absorb the change in the rotational phase, and the electromagnetic brake control signals of the respective electromagnetic brakes are controlled. Control signal,
It is adjusted so that the rotation phase is not changed, that is, the torques acting in the direction of changing the rotation phase are the same. Then, when the difference between the control signals in the state where the rotation phase is adjusted so as not to change is large enough to exceed the normal level and the abnormal state is absorbed, it is determined that an abnormality has occurred.

According to an eighth aspect of the present invention, when the change of the target of the rotational phase is below a predetermined value and continues for a predetermined time or more, the two electromagnetic brakes are simultaneously operated to perform diagnosis. And According to the above configuration, if the target rotation phase required from the engine operating conditions is stable and stable, the two electromagnetic brakes are simultaneously operated to perform diagnosis, but the target rotation phase changes. If so, the diagnosis is stopped so that the rotation phase required from the operating conditions can be obtained.

According to a ninth aspect of the present invention, in the variable valve timing mechanism, the driving rotary body to which rotation is transmitted from the crankshaft of the internal combustion engine and the driven rotary body on the camshaft side are provided with an assembly angle adjusting mechanism. Is connected coaxially, and the valve timing of the engine valve is changed by changing the assembling angle between the drive rotating body and the driven rotating body by the assembling angle adjusting mechanism. The mechanism has a diameter in which a rotating portion at one end is rotatably connected to one of the drive rotating body and the driven rotating body, and a slide portion at the other end is provided at the other of the drive rotating body and the driven rotating body. A guide plate provided with a link arm slidably connected in a radial direction by a direction guide and having a spiral guide for displacing the sliding portion in a radial direction is provided by two electromagnetic brakes. A configuration in which the position of the rotating portion is relatively displaced in the circumferential direction by rotating the drive rotating body relative to the decelerating direction and the accelerating direction to change the assembly angle between the drive rotating body and the driven rotating body. And

According to the above structure, by applying the braking force of the two electromagnetic brakes, the guide plate relatively rotates with respect to the driving rotor in the deceleration direction and the acceleration direction, whereby the slide portion is radially moved. In the variable valve timing mechanism having a configuration in which the position of the rotating portion is relatively displaced in the circumferential direction while being displaced, and the assembling angle (rotational phase of the camshaft with respect to the crankshaft) between the drive rotor and the driven rotor changes Two electromagnetic brakes that relatively rotate the guide plate are simultaneously actuated, and an abnormality (wear, coil current decrease, friction increase, etc.) of the variable valve timing mechanism is diagnosed based on the difference in torque generated at this time.

According to a tenth aspect of the invention, the guide plate is rotationally transmitted through a planetary gear mechanism having a carrier member as an input element, one of a sun gear and a ring gear as an output element, and the other as a free element. In addition, one of the two electromagnetic brakes applies braking to the output element and the other applies braking to the free element.

According to the above structure, the output element is decelerated by the operation of the electromagnetic brake that applies the braking to the output element, and the output element is accelerated by the operation of the electromagnetic brake that applies the braking to the free element. Control in the retard direction / advance direction is performed, and based on the difference in torque generated when the two electromagnetic brakes are simultaneously actuated, abnormality of the variable valve timing mechanism (electromagnetic brake wear) is detected. To be diagnosed.

[0023]

According to the first aspect of the present invention, the diagnosis is performed based on the difference between the torques generated when the two electromagnetic brakes are simultaneously actuated. Therefore, the diagnosis can be performed without a large change in the rotational phase. There is an effect that abnormality such as wear can be diagnosed with sufficient frequency and without adversely affecting drivability.

According to the second to fourth aspects of the invention, it is possible to estimate the change in the generated torque due to wear or the like from the change in the rotational phase when the two electromagnetic brakes are simultaneously actuated. There is an effect that abnormality such as wear can be diagnosed without adversely affecting. According to the invention described in claim 5, in consideration of the influence of the input torque from the camshaft side, the simultaneous operation can be performed by the control signal that does not cause the change of the rotation phase in the normal state. effective.

According to the sixth aspect of the present invention, in consideration of the change in the generated torque due to the temperature characteristic of the electromagnetic brake, the simultaneous operation is performed by the control signal that does not change the rotational phase under normal conditions. The effect is that you can. According to the invention described in claim 7, there is an effect that the diagnosis can be performed without changing the rotation phase even at the time of abnormality.

According to the invention described in claim 8, there is an effect that the diagnosis can be performed while controlling the rotational phase required from the operating condition. According to the invention of claim 9, a guide plate having a spiral guide is formed,
In the variable valve timing mechanism that changes the valve timing by rotating the crankshaft side relative to each other in the deceleration direction and the acceleration direction by two electromagnetic brakes, the variable valve timing mechanism wears at a sufficient frequency without adversely affecting the drivability. It is effective in diagnosing such abnormalities.

According to the tenth aspect of the present invention, in a mechanism that accelerates and decelerates by two electromagnetic brakes by using a planetary gear mechanism, wear and the like occur at a sufficient frequency and without adversely affecting drivability. There is an effect that the abnormality of can be diagnosed.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a vehicle internal combustion engine according to an embodiment, and an intake pipe 102 of the internal combustion engine 101.
The throttle motor 103a and throttle valve 1
An electronically controlled throttle 104 for opening and closing 03b is interposed, and the electronically controlled throttle 104 and the intake valve 10 are provided.
Air is sucked into the combustion chamber 106 via No. 5.

Combustion exhaust is discharged from the combustion chamber 106 to the exhaust valve 1.
It is discharged via 07, purified by the front catalyst 108 and the rear catalyst 109, and then discharged into the atmosphere. The intake valve 105 and the exhaust valve 107 are opened and closed by cams provided on the exhaust side cam shaft 110 and the intake side cam shaft 134, respectively, and the intake side cam shaft 134 changes the rotational phase with respect to the crankshaft 120. The variable valve timing mechanism VTC113 of the spiral radial link type that changes the valve timing by performing the above is provided.

In the present embodiment, the variable valve timing mechanism VTC113 is provided only on the intake valve side, but instead of the intake valve side or together with the intake valve side, the variable valve timing mechanism VTC1 is provided on the exhaust valve side.
A configuration including 13 may be used. Further, an electromagnetic fuel injection valve 131 is provided in the intake port 130 on the upstream side of the intake valve 105 of each cylinder, and the fuel injection valve 131 is
When the valve is driven to open by the injection pulse signal from the ECU 114, the fuel adjusted to a predetermined pressure is supplied to the intake valve 1.
It jets toward 05.

Detection signals from various sensors are input to an engine control unit (ECU) 114 containing a microcomputer, and the electronically controlled throttle 104, variable valve timing mechanism VTC 113 and Fuel injection valve 1
31 and the like are controlled. The various sensors include an accelerator opening sensor APS116 that detects an accelerator opening and an air flow meter 1 that detects an intake air amount Q of the engine 101.
15, a crank angle sensor 117 that extracts a rotation signal from the crankshaft 120, a throttle sensor 118 that detects the opening TVO of the throttle valve 103b, the engine 1
A water temperature sensor 119 for detecting the cooling water temperature of 01, a cam sensor 132 for extracting a rotation signal from the intake side camshaft 134, and the like are provided.

The engine speed Ne is calculated in the ECU 114 based on the rotation signal output from the crank angle sensor 117. Next, the configuration of the variable valve timing mechanism VTC 113 will be described with reference to FIGS. The variable valve timing mechanism VTC113
Is composed of a cam shaft 134, a drive plate 2, an assembly angle adjusting mechanism 4, an actuator 15, and a VTC cover 6.

The drive plate 2 is a member that rotates when the rotation is transmitted from the engine 101 (crankshaft 120), and the assembly angle adjusting mechanism 4 includes an assembly angle between the camshaft 134 and the drive plate 2. And is operated by the actuating device 15. The VTC
The cover 6 is a cover that is attached across the front ends of the cylinder head and the rocker cover (not shown) and covers the front surface of the drive plate 2 and the assembly angle adjusting mechanism 4 and the peripheral area thereof.

A spacer 8 is fitted to the front end portion (left side in FIG. 2) of the camshaft 134. Further, the spacer 8 is provided on the flange portion 134 of the camshaft 134.
The rotation is regulated by a pin 80 penetrating through f.
Further, a plurality of oil supply holes 134r are formed through the cam shaft 134 in the radial direction.

As shown in FIG. 3, the spacer 8 includes a disk-shaped locking flange 8a, a circular pipe portion 8b extending axially from the front end surface of the locking flange 8a, and a front end of the locking flange 8a. A shaft support portion 8d is formed which is a surface and extends from the base end side of the circular pipe portion 8b in three directions in the outer diameter direction and in which a press-fitting hole 8c parallel to the axial direction is formed. The shaft support portion 8d and the press-fitting holes 8c are arranged at intervals of 120 ° in the circumferential direction, as shown in FIG.

An oil supply hole 8r for supplying oil is formed through the spacer 8 in the radial direction. The drive plate 2 is formed in a disk shape having a through hole 2a formed in the center thereof, and is rotatably assembled to the spacer 8 in a state in which axial displacement is restricted by a locking flange 8a. ing.

Further, as shown in FIG. 3, the drive plate 2 has a timing sprocket 3 formed on the outer periphery of the rear portion thereof, the rotation of which is transmitted from the crankshaft 120 via a chain (not shown). Further, on the front end surface of the drive plate 2, three guide grooves 2g are formed in the outer diameter direction by connecting the through hole 2a and the outer periphery, and the guide groove 2g is similar to the shaft support portion 8d. 120 ° in the circumferential direction
It is arranged for each.

An annular cover member 2c is fixed to the outer peripheral portion of the front end surface of the drive plate 2 by welding or press fitting. In the present embodiment, the driven rotating body is constituted by the cam shaft 134 and the spacer 8, and the driving rotating body is constituted by the drive plate 2 including the timing sprocket 3.

The assembly angle adjusting mechanism 4 includes the camshaft 1
34 is arranged on the front end side of the drive plate 2 and the drive plate 2, and changes the relative angle of assembly between the cam shaft 134 and the drive plate 2. The assembly angle adjusting mechanism 4 has three link arms 14 as shown in FIG.

Each of the link arms 14 is provided with a cylindrical portion 14a as a slide portion at the tip thereof, and an arm portion 14b extending from the cylindrical portion 14a in the outer diameter direction. A housing hole 14c is formed through the cylindrical portion 14a, while a rotation hole 14d as a rotation portion is formed through the base end of the arm portion 14b.

The link arm 14 includes the spacer 8
The turning hole 14 is attached to the turning pin 81 that is tightly press-fitted into the press-fitting hole 8c, and is attached so as to be rotatable about the turning pin 81. On the other hand, the cylindrical portion 14a of the link arm 14 is inserted into a guide groove 2g as a radial guide of the drive plate 2 and is attached to the drive plate 2 so as to be movable (sliding) in the radial direction.

In the above structure, when the cylindrical portion 14a receives an external force and slides in the radial direction along the guide groove 2g, the pivot pin 81 is displaced in the radial direction of the cylindrical portion 14a by the link action of the link arm 14. The cam shaft 134 is moved by the displacement of the rotation pin 81 in the circumferential direction by an angle corresponding to the drive plate 2.
It will rotate relative to.

FIGS. 4 and 5 show the operation of the assembling angle adjusting mechanism 4. As shown in FIG. 4, the cylindrical portion 14a is arranged on the outer peripheral side of the drive plate 2 in the guide groove 2g. In some cases, the pivot pin 81 at the base end portion may cause the guide groove 2
It is pulled to a position close to g, and this position is the most retarded position. On the other hand, as shown in FIG.
When a is arranged on the inner peripheral side of the drive plate 2 in the guide groove 2g, the rotating pin 81 is pushed in the circumferential direction and moves away from the guide groove 2g, and this position is the most advanced position.

The movement of the cylindrical portion 14a in the assembly angle adjusting mechanism 4 in the radial direction is performed by the actuating device 15, and the actuating device 15 includes an actuation conversion mechanism 40 and an acceleration / deceleration mechanism 41. There is. The operation conversion mechanism 40 includes a sphere 22 held by the cylindrical portion 14a of the link arm 14,
And a guide plate 24 provided coaxially to face the front surface of the drive plate 2.
Is a mechanism that converts the rotation of the above into a radial displacement of the cylindrical portion 14a of the link arm 14.

The guide plate 24 is rotatably supported on the outer circumference of the circular pipe portion 8b of the spacer 8 via a metal bush 23. On the rear surface of the guide plate 24, there is formed a spiral guide groove 28 as a spiral guide which has a substantially semicircular cross section and is displaced in the radial direction along with the displacement in the circumferential direction. Is formed with an oil supply hole 24r for supplying oil penetrating in the front-rear direction.

The sphere 22 is provided in the spiral guide groove 28.
Are engaged. That is, the accommodating hole 14c formed in the cylindrical portion 14a of the link arm 14 has a structure shown in FIGS.
As shown in FIG. 5, a disc-shaped support panel 22a, a coil spring 22b, a retainer 22c, and a ball 22 are sequentially inserted. Further, the retainer 22c has a bowl-shaped supporting recess 2 that supports the ball 22 in a state where the ball 22 is projected at the front end.
2d is formed, and a flange 22f on which the coil spring 22b is seated is formed on the outer circumference.

In the assembled state shown in FIG. 2, the coil spring 22b is compressed, the support panel 22a is pressed against the front surface of the drive plate 2, and the sphere 22 is pressed against the spiral guide groove 28 to move up and down. Direction engagement, and relative movement is possible in the extending direction of the spiral guide groove 28. Further, the spiral guide groove 28 is
As shown in FIGS. 4 and 5, the drive plate 2 is formed so as to gradually reduce its diameter along the rotational direction R.

Therefore, in the operation conversion mechanism 40, when the guide plate 24 rotates relative to the drive plate 2 in the rotation direction R with the ball 22 engaged with the spiral guide groove 28, the ball 22 swirls. The guide portion 28 moves radially outward along the spiral shape of the guide groove 28, whereby the cylindrical portion 14a as the slide portion moves in the outer diameter direction shown in FIG. 4, and the rotating pin 81 connected to the link arm 14 is moved. Is pulled toward the guide groove 2g, and the camshaft 1
34 moves in the retard direction.

On the contrary, when the guide plate 24 rotates relative to the drive plate 2 in the direction opposite to the rotation direction R from the above state, the sphere 22 moves radially inward along the spiral shape of the spiral guide groove 28. As a result, the cylindrical portion 14a as the slide portion moves in the inner diameter direction shown in FIG.
The rotation pin 81 connected to the link arm 14 is pushed in a direction away from the guide groove 2g, and in this case, the cam shaft 134 moves in the advance direction.

Next, the acceleration / deceleration mechanism 41 will be described in detail. The acceleration / deceleration mechanism 41 includes the guide plate 24.
With respect to the drive plate 2, and the guide plate 24 is moved (accelerated) in the rotation direction R side with respect to the drive plate 2, or the guide plate 24 is rotated with respect to the drive plate 2 in the rotation direction R. It is moved (decelerated) to the opposite side, and is provided with a planetary gear mechanism 25, a first electromagnetic brake 26, and a second electromagnetic brake 27.

The planetary gear mechanism 25 includes a sun gear 30.
, A ring gear 31, and a planetary gear 33 meshed with both gears 30, 31. As shown in FIGS. 2 and 3, the sun gear 30 includes a guide plate 24.
Is integrally formed on the inner circumference on the front side of the. The planetary gear 33 is rotatably supported by a carrier plate 32 fixed to the front end of the spacer 8.

The ring gear 31 is formed on the inner circumference of an annular rotating body 34 which is rotatably supported outside the carrier plate 32. The carrier plate 32 is fitted to the front end of the spacer 8,
With the washer 37 abutting on the front end, the bolt 9 is passed through and fastened to the cam shaft 134 to be fixed.

A braking plate 35 having a braking surface 35b facing forward is screwed to the front end surface of the rotating body 34. A braking plate 36 having a braking surface 36b facing forward is also fixed to the outer periphery of the guide plate 24 integrally formed with the sun gear 30 by welding or fitting.

Therefore, in the planetary gear mechanism 25, if the planetary gear 33 revolves together with the carrier plate 32 without rotating, the first electromagnetic brake 26 and the second electromagnetic brake 26.
When the electromagnetic brake 27 is inactive, the sun gear 30 and the ring gear 31 rotate at the same speed in a free state. When only the first electromagnetic brake 26 is braked from this state, the guide plate 24 rotates relative to the carrier plate 32 (relative to the camshaft 134) in the direction behind (the direction opposite to the R direction in FIGS. 4 and 5). Then, the drive plate 2 and the cam shaft 134 are relatively displaced in the advance direction shown in FIG.

On the other hand, when only the second electromagnetic brake 27 is braked, a braking force is applied only to the ring gear 31, and the ring gear 31 rotates relative to the carrier plate 32 in the delay direction, so that the planetary gear 33 rotates about its own axis. The rotation of the planetary gears 33 speeds up the sun gear 30, the guide plate 24 rotates relative to the drive plate 2 in the rotation direction R side, and the drive plate 2 and the camshaft 134 rotate in the retard direction shown in FIG. Will be done.

In this embodiment, the carrier plate 32 is an input element, the sun gear 30 is an output element, and the ring gear 31 is a free element. The first electromagnetic brake 26 and the second electromagnetic brake 27 are the braking surfaces 36b, 35b of the braking plates 36, 35 described above, respectively.
Circular pipe members 26r, 27r that are arranged in a double manner inside and outside so as to face each other and are supported on the back surface of the VTC cover 6 in a floating state in which only rotation is restricted by pins 26p, 27p.
have.

Coils 26c and 27c are housed in these circular pipe members 26r and 27r, and friction materials 26b and 27b that are pressed against the braking surfaces 35b and 36b when the coils 26c and 27c are energized are mounted. Has been done. The circular pipe members 26r and 27r and the braking plates 35 and 36 are made of a magnetic material such as iron so as to form a magnetic field when the coils 26c and 27c are energized.

On the other hand, since the VTC cover 6 does not cause leakage of magnetic flux when energized, the friction members 26b and 27b are made permanent magnets and adhered to the braking plates 35 and 36 when de-energized. To prevent this, it is made of a non-magnetic material such as aluminum. The relative rotation between the guide plate 24 provided with the sun gear 30 as an output element of the planetary gear mechanism 25 and the drive plate 2 is restricted by the assembly angle stopper 60 at the most retarded position and the most advanced position. Has become.

Further, in the planetary gear mechanism 25, the braking plate 3 provided integrally with the ring gear 31.
A planetary gear stopper 90 is provided between the carrier 5 and the carrier plate 32. By the way, the operation conversion mechanism 40 described above holds the position of the cylindrical portion 14a of the link arm 14, and the drive plate 2 and the cam shaft 134 are held.
Since the relative assembly position with respect to and does not change, the configuration will be described.

From the drive plate 2 to the camshaft 13
The driving torque is transmitted to the shaft 4 through the link arm 14 and the spacer 8, but the fluctuation torque of the cam shaft 134 due to the reaction force from the engine valve (the intake valve 105) is transferred from the cam shaft 134 to the link arm 14. , Is input as a force F from the rotating pin 81 in the direction connecting the pivot points of both ends of the link arm 14.

The cylindrical portion 14a of the link arm 14 is
Since the sphere 22 which is guided in the radial direction along the guide groove 2g as a radial guide and which projects from the cylindrical portion 14a to the front is engaged with the spiral guide groove 28, each link arm 14 is The force F input through the guide groove 2g is supported by the left and right walls of the guide groove 2g and the spiral guide groove 28 of the guide plate 24.

Therefore, the force F input to the link arm 14 is decomposed into two component forces FA and FB which are orthogonal to each other, and these component forces FA and FB are combined into the spiral guide structure 2.
The outer peripheral wall of 8 and the one wall of the guide groove 2g are received in a direction substantially orthogonal to each other, and the cylindrical portion 1 of the link arm 14 is received.
4a is prevented from moving along the guide groove 2g,
This prevents the link arm 14 from rotating.

Therefore, after the guide plate 24 is rotated by the braking force of the electromagnetic brakes 26 and 27 and the link arm 14 is rotated to a predetermined position, basically, the braking force is not continuously applied. Even if the position of the link arm 14 is maintained, that is, the drive plate 2 and the cam shaft 134 are
The rotation phase of can be maintained as it is. The force F is not limited to acting in the outer diameter direction, but may act in the opposite inner diameter direction. At this time, the component force FA,
FB is the inner wall of the spiral guide groove 28 and the guide structure 2
It is received at a right angle to the other side of g.

Hereinafter, the variable valve timing mechanism VT will be described.
The operation of C113 will be described. When controlling the rotation phase of the crankshaft and the camshaft 134 to the retard side,
The second electromagnetic brake 27 is energized. Second electromagnetic brake 2
7, the friction material 27b of the second electromagnetic brake 27 is energized.
Comes into frictional contact with the braking plate 35, a braking force acts on the ring gear 31 of the planetary gear mechanism 25, and the sun gear 30 is rotated at an increased speed as the timing sprocket 3 rotates.

The guide plate 24 is rotated in the rotation direction R side with respect to the drive plate 2 by the accelerated rotation of the sun gear 30, and the sphere 22 supported by the link arm 14 is formed with the spiral guide groove 28. Move to the outer circumference.
This movement toward the retard angle side is performed by the assembling angle stopper 60 as shown in FIG.
It is regulated at the most retarded position shown in.

Further, as described above, when the rotation of the ring gear 31 is braked by the second electromagnetic brake 27, the rotation is not regulated instantaneously but is allowed while allowing a predetermined amount of rotation. The rotation of the ring gear 31 is restricted by the planetary gear stopper 90 when the value becomes a predetermined amount. On the other hand, when the mounting angle of the camshaft 134 is displaced in the advance direction, the first brake 26 is energized.

As a result, the braking force acts on the guide plate 24, and the guide plate 24 rotates in the direction opposite to the rotation direction R with respect to the drive plate 2, and the camshaft 13
4, the mounting angle is displaced to the advance side. This movement toward the advance angle side is restricted by the assembling angle stopper 60 at the most advanced angle position shown in FIG. 5, and when the rotation of the guide plate 24 is restricted, the planetary gear 33 rotates and the ring gear 31 increases. Although it is rotated at a high speed, when the rotation amount reaches a predetermined amount, the rotation is restricted by the planetary gear stopper 90.

The ECU 114 uses the crankshaft 1
A target advance angle value (target rotation phase) of the camshaft 134 with respect to 20 is set based on operating conditions of the engine, and the first electromagnetic brake 26 and the second electromagnetic brake 27 are energized based on the target advance angle value. It is designed for feedback control. Specifically, the duty ratio when controlling the average applied voltage by on / off controlling the energization of the electromagnetic brakes 26 and 27 at a high frequency is based on the detection signal of the crank angle sensor 117 and the detection signal of the cam sensor 132. By performing a calculation based on the deviation between the actual advance value (actual rotation phase) detected by the above and the target advance value, feedback control is performed so that the actual advance value matches the target.

Further, the ECU 114 has a diagnostic function of the variable valve timing mechanism VTC 113 as shown in the flowchart of FIG. In the flowchart of FIG. 6, in step S1, it is determined whether or not a precondition for diagnosis is satisfied. In this step S1, for example, when the battery voltage VB is equal to or higher than a predetermined value,
In addition, it is determined that the diagnosis condition is satisfied when the engine is not started.

If the diagnosis condition is satisfied, the process proceeds to step S2, and it is determined whether or not the change in the target advance value (target valve timing) is less than or equal to a predetermined value. Step S
When it is determined in 2 that the change in the target advance angle value (target valve timing) exceeds the predetermined value, the routine is terminated without diagnosing, so that the normal valve timing control is performed and the change is made. The actual advance value is made to follow the target advance value that is being set.

On the other hand, when it is determined in step S2 that the change in the target advance value (target valve timing) is less than or equal to the predetermined value, the process proceeds to step S3. In step S3,
It is determined whether or not the state where the change in the target advance value (target valve timing) is equal to or less than a predetermined value has continued for a predetermined time or more. When the state where the change in the target advance value (target valve timing) is less than or equal to the predetermined value is the steady state in which the change continues for the predetermined time or more, the process proceeds to step S4 to perform diagnosis, but the duration is longer than the predetermined time. When the number is small, this routine is ended without making a diagnosis.

In step S4, a diagnostic control signal is output to the electromagnetic brakes 26 and 27 so that the torque acting in the advance direction and the torque acting in the retard angle coincide with each other.
The two electromagnetic brakes 26 and 27 are forcibly operated simultaneously. Here, if there is no abnormality such as wear in the electromagnetic brakes 26 and 27, the torque actually acting in the advance angle direction and the torque acting in the retard angle direction match and the rotation phase does not change. If the torque commensurate with the control signal is not generated, the torque balance is lost and the rotation phase changes to the advance side or the retard side.

The diagnostic control signal that causes the torque acting in the advance angle direction and the torque acting in the retard angle direction to coincide with each other can be stored in advance as a fixed value.
Since the correlation between the control signal and the torque actually acting in the advance / retard direction changes depending on the input torque (reaction force) from the camshaft side and the temperature characteristics of the electromagnetic brakes 26 and 27,
It is preferable to set the diagnostic control signal each time based on the input torque from the camshaft side and the temperature characteristic.

The input torque (reaction force) from the camshaft side increases as the engine speed increases, and when a variable valve lift mechanism that changes the valve lift amount is provided, the valve lift amount increases. The input torque (reaction force) from the camshaft side acts so as to prevent the rotation phase from changing.
Therefore, according to the engine rotation speed and the valve lift amount that are correlated with the input torque from the camshaft side, the diagnostic control signal (drive current) is increased and corrected as the input torque from the camshaft side increases. A diagnostic control signal that reliably changes the rotation phase when the friction surface of the brake is worn, and does not change the rotation phase due to a slight difference in generated torque between two electromagnetic brakes. It is preferable that

Even if the same voltage is applied to the electromagnetic coils 26 and 27, the current flowing through the coils changes depending on the coil temperature, and the generated torque changes. Therefore, it is preferable to correct the diagnostic control signal based on the coil temperature estimated from the lubricating oil temperature and the like. Further, when the temperature characteristics of the electromagnetic coils 26 and 27 are different, the individual differences are considered in consideration of the difference in the temperature characteristics. It is preferable to add a correction to.

In step S4, a diagnostic control signal is output to the electromagnetic brakes 26 and 27 so that the torque acting in the advance direction and the torque acting in the retard direction coincide with each other to output the two electromagnetic brakes 26, 27. When the two are forcibly operated simultaneously, in the next step S5, it is determined whether or not the rotation phase has changed to a predetermined value or more. Since the control signal for diagnosis is given as a value such that the torque acting in the advance direction and the torque acting in the retard direction coincide with each other, if there is no abnormality such as abrasion of the friction surface, the change in the rotation phase does not occur. It never happens.

Therefore, when it is determined in step S5 that the amount of change in the rotational phase is smaller than the predetermined value, the process proceeds to step S6, in which the energization of the electromagnetic brakes 26 and 27 is stopped and the normality determination signal is output. To do. On the other hand, when it is determined in step S5 that the rotation phase has changed more than the predetermined value, the torque is actually lower than the torque predicted from the control signal due to the progress of wear in one electromagnetic brake, the decrease in coil current, and the increase in friction. It is presumed that the torque generated on the side becomes smaller, the torque on the side on which wear or the like does not occur wins, and the rotation phase changes.

Therefore, when it is determined in step S5 that the rotational phase has changed by a predetermined amount or more, the process proceeds to step S7, the energization of the electromagnetic brakes 26 and 27 is stopped, and the abnormality determination signal is output. When the abnormality determination signal is output, the control based on the target rotation phase is prohibited, and it is preferable to forcibly return to the most retarded angle position to hold the most retarded angle position or to limit the advance amount.

When the abnormality determination signal is output,
It is advisable to warn the driver of the vehicle that an abnormality has occurred by displaying a lamp or warning characters. As described above, if the configuration is such that the abnormality diagnosis is performed, the abnormality diagnosis can be performed while the target advance value does not change, and a diagnosis opportunity can be secured. Is not changed, and the drivability is not adversely affected.

In step S5, it is determined whether or not the amount of change in the rotational phase is greater than or equal to a predetermined value. However, the changing speed of the rotational phase (absolute of the deviation between the current value and the previous value of the rotational phase) is determined. Value) is greater than or equal to a predetermined value,
It is possible to adopt a configuration in which an abnormality determination is made when the rotational phase change speed is equal to or higher than a predetermined value. The flowchart of FIG. 7 shows another embodiment of the diagnostic control, and in steps S11 to S13, like the steps S1 to S3,
Make the condition for diagnosis diagnosed.

When the diagnostic condition is satisfied, the routine proceeds to step S14, where a diagnostic control signal is output to the electromagnetic brakes 26 and 27 to operate the electromagnetic brakes 26 and 27 at the same time. The diagnostic control signal may be a fixed value or may be changed according to the input torque and temperature characteristics from the camshaft side, but as will be described later, the rotational phase is maintained. Since the feedback control is performed, it is not necessary to align the generated torque with high accuracy.

In step S15, feedback control is performed to increase / decrease the drive currents of the electromagnetic brakes 26 and 27 so that the rotation phase before the start of diagnosis is maintained. In step S16, as a result of the feedback control, it is determined whether or not the rotational phase has converged to a value before the start of diagnosis, and until converged, the process returns to step S15 to continue the feedback control.

When it is determined in step S16 that the rotation phase has converged to the value before the start of diagnosis, the process proceeds to step S17, in which the absolute value of the difference between the control signals (duty) of the electromagnetic brakes 26 and 27 is It is determined whether or not it is equal to or larger than a predetermined value. In one of the electromagnetic brakes 26 and 27, when the friction surface is worn, the coil current is decreased, and the friction is increased, and the torque for changing the rotation phase is decreased relative to the torque of the other electromagnetic brake, In the feedback control of step S15, the control signal (driving current) on the side where the abnormality has occurred is increased so as to avoid a change in the rotational phase due to the decrease in torque.
Since the torque shortage will be compensated, the electromagnetic brake 26,
The difference in the control signal (duty) between the Nos. 27 increases.

Therefore, when the absolute value of the difference between the control signals (duty) of the electromagnetic brakes 26 and 27 is larger than the normal time, one of the electromagnetic brakes 26 and 27 is
It is estimated that an abnormality such as wear of the friction surface, a decrease in coil current, an increase in friction, etc. occurred, and a large control signal (duty) difference occurred in order to compensate for the relative torque shortage due to the abnormality.

Therefore, when the absolute value of the difference between the control signals (duty) of the electromagnetic brakes 26 and 27 is smaller than the predetermined value, the process proceeds to step S18, and the electromagnetic brakes 26 and 2 are operated.
When the absolute value of the difference between the control signals (duty) is equal to or larger than a predetermined value, the power supply to the electromagnetic brakes 26 and 27 is stopped. At the same time, an abnormality determination signal is output.

The processing when the abnormality determination signal is output is as follows.
Processing similar to that described in the flowchart of FIG. 6 may be performed. According to the above-mentioned diagnostic control, even if the electromagnetic brakes 26 and 27 are abnormal, the rotation phase can be held and the diagnosis can be performed without changing the rotation phase.

The above embodiment is directed to the spiral radial link type variable valve timing mechanism having a structure in which a guide plate having a spiral guide is relatively rotated in two advancing and retarding directions by two electromagnetic brakes. However, the variable valve timing mechanism is not limited to the spiral radial link type, and may be any variable valve timing mechanism configured to change the rotational phase of the camshaft with respect to the crankshaft in the advance direction and the retard direction by the braking force of the two electromagnetic brakes. The above diagnostic control can be applied.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an internal combustion engine according to an embodiment.

FIG. 2 is a cross-sectional view showing a variable valve timing mechanism in the embodiment.

FIG. 3 is an exploded perspective view of the variable valve timing mechanism.

FIG. 4 is a cross-sectional view taken along the line AA of FIG. 2 showing an operation of a main part of the variable valve timing mechanism.

5 is a cross-sectional view taken along the line AA of FIG. 2 showing the operation of the main part of the variable valve timing mechanism.

FIG. 6 is a flowchart showing a first embodiment of diagnostic control of a variable valve timing mechanism.

FIG. 7 is a flowchart showing a second embodiment of the diagnostic control of the variable valve timing mechanism.

[Explanation of symbols]

2 ... Drive plate 2g ... Guide groove 3 ... Timing sprocket 4 ... Assembly angle adjustment mechanism 6 ... VTC cover 8 ... Spacer 14 ... Link arm 15 ... Actuator 24 ... Guide plate 25 ... Planetary gear mechanism 26 ... First electromagnetic brake 27 ... Second electromagnetic brake 28 ... Spiral guide groove 30 ... Sun gear 31 ... Ring gear 32 ... Carrier plate 33 ... Planetary gear 35 ... Braking plate 36 ... Braking plate 40 ... Operation conversion mechanism 41 ... Acceleration / deceleration mechanism 101 ... Internal combustion engine 105 ... intake valve 113 ... Variable valve timing mechanism VTC 114 ... Engine control unit 117 ... Crank angle sensor 119 ... Water temperature sensor 120 ... crankshaft 132 ... Cam sensor 134 ... Camshaft

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3G018 BA32 CA04 CA12 DA21 DA37                       EA23 FA07 GA40                 3G084 BA02 BA23 DA27 EB12 FA20                       FA33                 3G092 AA11 DA09 DG09 EA03 EA04                       EA17 EA26 EA27 EC01 FA36                       FB06 HA13X HA13Y HA13Z                       HE01Z HE08Z

Claims (10)

[Claims] 1. A variable valve timing mechanism for changing a valve timing of an engine valve by changing a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine in an advance direction and a retard direction by braking forces of two electromagnetic brakes. In the variable valve timing mechanism, the two electromagnetic brakes are forcibly actuated simultaneously, and whether or not there is an abnormality in the variable valve timing mechanism is diagnosed based on a difference in torque generated in the simultaneously actuated state. Diagnostic device. 2. A variable valve timing mechanism for changing a valve timing of an engine valve by changing a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine by advancing and retarding directions by braking forces of two electromagnetic brakes. In the variable valve timing mechanism diagnosis system according to claim 1, the presence or absence of abnormality of the variable valve timing mechanism is diagnosed based on a change in the rotational phase when the two electromagnetic brakes are forcibly operated simultaneously. . 3. The two electromagnetic brakes are simultaneously actuated on the basis of a diagnostic control signal in which the drive torque in the advance direction and the drive torque in the retard direction by the two electromagnetic brakes are the same when normal, and the rotational phase at this time The variable valve timing mechanism diagnosing device according to claim 2, wherein an abnormality of the variable valve timing mechanism is determined when the change amount of the variable valve timing mechanism is greater than or equal to a predetermined value. 4. The two electromagnetic brakes are simultaneously actuated on the basis of a diagnostic control signal in which the drive torque in the advance direction and the drive torque in the retard direction by the two electromagnetic brakes are the same when normal, and the rotational phase at this time The variable valve timing mechanism diagnosing device according to claim 2, wherein an abnormality of the variable valve timing mechanism is determined when the change speed of the variable valve timing mechanism is equal to or more than a predetermined value. 5. The diagnostic device for a variable valve timing mechanism according to claim 3, wherein the diagnostic control signal is set according to an input torque from the camshaft side. 6. The diagnostic device for a variable valve timing mechanism according to claim 3, wherein the diagnostic control signal is set according to the temperature characteristics of each of the two electromagnetic brakes. 7. A variable valve timing mechanism for changing a valve timing of an engine valve by changing a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine in an advance direction and a retard direction by braking forces of two electromagnetic brakes. In the above, the two electromagnetic brakes are forcibly operated simultaneously, and the control signals of the respective electromagnetic brakes are feedback-controlled so that the rotation phase maintains a constant position, and the rotation phase maintains a constant position. A diagnostic device for a variable valve timing mechanism, characterized by diagnosing whether or not there is an abnormality in the variable valve timing mechanism based on a difference between control signals of respective electromagnetic brakes. 8. The diagnosis is performed by simultaneously activating the two electromagnetic brakes when the target change of the rotational phase is below a predetermined value for a predetermined time or more. The variable valve timing mechanism diagnostic device according to any one of 1 to 7. 9. In the variable valve timing mechanism, a driving rotary body to which rotation is transmitted from a crankshaft of an internal combustion engine and a driven rotary body on the camshaft side are coaxially connected via an assembly angle adjusting mechanism, A configuration for changing the valve timing of the engine valve by changing the assembly angle of the drive rotating body and the driven rotating body by the assembly angle adjusting mechanism, wherein the assembly angle adjusting mechanism has one end A part is rotatably connected to one of the drive rotating body and the driven rotating body,
The spiral part for displacing the slide part in the radial direction is provided with a link arm whose slide part at the other end is slidably connected in the radial direction by a radial guide provided on the other of the driving rotary body and the driven rotary body. By relatively rotating the guide plate on which the guide is formed in the decelerating direction and the speed increasing direction with respect to the drive rotating body by the two electromagnetic brakes, the position of the rotating portion is relatively displaced in the circumferential direction,
9. The structure according to claim 1, wherein the assembling angle between the driving rotary body and the driven rotary body is changed.
Diagnostic device for variable valve timing mechanism as described in 1. 10. A structure in which the guide plate is rotationally transmitted via a planetary gear mechanism having a carrier member as an input element, one of a sun gear and a ring gear as an output element, and the other as a free element, The variable valve timing mechanism diagnosing device according to claim 9, wherein one of two electromagnetic brakes applies braking to the output element and the other applies braking to the free element.