JP4027672B2 - Control device for variable valve timing mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a variable valve timing mechanism that changes the valve timing of an engine valve (intake / exhaust valve).
[0002]
[Prior art]
Conventionally, as a variable valve timing mechanism, an assembly angle adjustment mechanism is used to change an assembly angle between a drive rotor that receives rotation from a crankshaft of an internal combustion engine and a driven rotor on the camshaft side. There is known a configuration in which the opening / closing timing of the valve is changed to the advance side and the retard side with respect to the crank angle.
[0003]
For example, in the assembly angle adjusting mechanism of the variable valve timing mechanism disclosed in Japanese Patent Application Laid-Open No. 2001-041013, the rotating part at one end is rotatably connected to one of the driving rotating body and the driven rotating body, and the other The slide portion at the end includes a link arm that is slidably connected in a radial direction by a radial guide provided on the other of the driving rotary body and the driven rotary body, and the rotary portion is moved along with the radial movement of the slide portion. The assembly position of the drive rotator and the driven rotator is relatively changed so as to relatively change in the circumferential direction, and a spiral guide that engages the slide portion of the link arm is formed. Further, by controlling the relative rotation angle of the guide plate with the braking force of the electromagnetic brake, the slide portion is displaced in the radial direction, so that the valve timing is advanced / retarded.
[0004]
Hereinafter, the variable valve timing mechanism including the assembly angle adjusting mechanism having the above-described configuration is referred to as a spiral radial link type.
[0005]
[Problems to be solved by the invention]
By the way, in the spiral radial link type variable valve timing mechanism disclosed in Japanese Patent Laid-Open No. 2001-041013, the guide plate is biased in the retarded direction of the valve timing by the spring, so that the electromagnetic brake is Turning it off will return it to the most retarded angle position, but as in Japanese Patent Application No. 2001-319908 filed earlier by the present applicant, control of the advance angle direction and the retard angle direction are performed by two electromagnetic brakes, respectively. In this case, the valve timing is changed by applying the braking force of the electromagnetic brake in both the advance direction and the retard direction.
[0006]
In the spiral radial link type variable valve timing mechanism that controls the delay angle and advance angle by the two electromagnetic brakes, the coil temperature characteristics of the two electromagnetic brakes differ depending on the temperature environment and heat generation characteristics. Therefore, there is a possibility that a difference occurs in the drive current (generated torque) flowing in the coil, and thus a difference in response occurs depending on the control direction.
[0007]
Accordingly, the present invention provides a variable valve timing mechanism that controls the advance angle direction and the retard angle direction with two electromagnetic brakes, even if the temperature characteristics of the two electromagnetic brakes are different, the desired response regardless of the change direction. It is an object of the present invention to provide a control device that can perform feedback control of valve timing by the characteristics.
[0008]
[Means for Solving the Problems]
Therefore, the invention of claim 1The target drive current of the first electromagnetic brake and the target drive current of the second electromagnetic brake are respectively set based on the target value of the rotation phase and the actual rotation phase, while the coil of the first electromagnetic brake is actually set , And the drive current actually flowing in the coil of the second electromagnetic brake are respectively detected, and the control amounts of the drive currents of the first electromagnetic brake and the second electromagnetic brake are respectively determined. Feedback control is performed on the basis of the detected value of each drive current and the target drive current.
[0011]
According to the above configuration, the target drive current for each of the two electromagnetic brakes is set based on the target value of the rotation phase (valve timing) and the actual rotation phase, and the actual drive current of each electromagnetic brake is set to the target drive current. Feedback control is performed for each electromagnetic brake so as to match. Claim2In the described invention, the variable valve timing mechanism is configured such that a driving rotating body whose rotation is transmitted from a crankshaft of an internal combustion engine and a driven rotating body on the camshaft side are coaxially connected via an assembly angle adjusting mechanism, The assembly angle adjustment mechanism is configured to change the valve timing of the engine valve by changing the assembly angle between the drive rotator and the driven rotator, and the assembly angle adjustment mechanism rotates at one end. Is rotatably connected to one of the drive rotator and the driven rotator, and a slide portion at the other end is radially provided by a radial guide provided on the other of the drive rotator and the driven rotator. A guide plate that includes a link arm that is slidably connected, and in which a spiral guide that radially displaces the slide portion is formed,First and secondBy relative rotation in the deceleration direction and acceleration direction with respect to the drive rotator by an electromagnetic brake, the position of the rotating part is relatively displaced in the circumferential direction, and the assembly angle between the drive rotator and the driven rotator is set. The configuration was changed.
[0012]
According to the above configuration, by applying the braking force of the two electromagnetic brakes, the guide plate rotates relative to the drive rotating body in the deceleration direction and the speed increasing direction, thereby displacing the slide portion in the radial direction. In the variable valve timing mechanism having a configuration in which the position of the rotating portion is relatively displaced in the circumferential direction and the assembly angle (the rotational phase of the camshaft with respect to the crankshaft) between the driving rotating body and the driven rotating body changes. For each brake, feedback control is performed so that the actual drive current matches the target value, and variations in drive current due to temperature characteristics are individually absorbed.
[0013]
Claim3In the described invention, the guide plate is configured to be 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,Said first electromagnetic brakeGives braking to the output element,Said second electromagnetic brakeIs configured to apply braking to the free element. According to the above configuration, braking is applied to the output element.FirstThe output element is decelerated by the operation of the electromagnetic brake, and braking is applied to the free element.SecondThe speed of the output element is increased by the operation of the electromagnetic brake, so that the control in the retarding direction and the advance direction is performed by the two electromagnetic brakes, and feedback based on the target drive current in each of the deceleration / acceleration control. Control is performed individually.
[0014]
【The invention's effect】
According to the invention of claim 1,The actual drive current can be made to coincide with the target drive current for each electromagnetic brake to obtain the target rotational phase (valve timing), and therefore the direction of change even if the temperature characteristics of the two electromagnetic brakes are different. The valve timing can be feedback controlled with the desired response regardless ofThere is an effect.
[0016]
Claim2According to the described invention, the variable valve timing mechanism that changes the valve timing by rotating the guide plate formed with the spiral guide relative to the crankshaft side in the deceleration direction and the acceleration direction by two electromagnetic brakes. However, even if the temperature characteristics of the two electromagnetic brakes are different, there is an effect that a required generation torque corresponding to the target drive current can be generated in each electromagnetic brake.
[0017]
Claim3According to the described invention, in a mechanism for performing acceleration / deceleration by two electromagnetic brakes by using a planetary gear mechanism, even if the temperature characteristics of the two electromagnetic brakes are different, they are on the acceleration side or on the deceleration side. Regardless of this, the valve timing can be feedback-controlled with a desired response.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an internal combustion engine for a vehicle according to an embodiment. An electronic control throttle 104 that opens and closes a throttle valve 103b by a throttle motor 103a is interposed in an intake pipe 102 of the internal combustion engine 101. Air is sucked into the combustion chamber 106 through the throttle 104 and the intake valve 105.
[0019]
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 intake valve 105 and the exhaust valve 107 are driven to open and close by cams provided on the exhaust side camshaft 110 and the intake side camshaft 134, respectively, but the intake side camshaft 134 changes the rotational phase with respect to the crankshaft 120. Thus, a spiral radial link type variable valve timing mechanism VTC 113 for changing the valve timing is provided.
[0020]
In this embodiment, the variable valve timing mechanism VTC113 is provided only on the intake valve side. However, the variable valve timing mechanism VTC113 is provided on the exhaust valve side instead of the intake valve side or together with the intake valve side. There may be.
Further, an electromagnetic fuel injection valve 131 is provided in the intake port 130 upstream of the intake valve 105 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal from the ECU 114, The fuel adjusted to a predetermined pressure is injected toward the intake valve 105.
[0021]
Detection signals from various sensors are input to an engine control unit (ECU) 114 having a built-in microcomputer, and the electronic control throttle 104, the variable valve timing mechanism VTC 113, and the fuel injection valve are subjected to arithmetic processing based on the detection signals. 131 and the like are controlled.
Examples of the various sensors include an accelerator opening sensor APS116 for detecting the accelerator opening, an air flow meter 115 for detecting the intake air amount Q of the engine 101, a crank angle sensor 117 for extracting a rotation signal from the crankshaft 120, and an opening of the throttle valve 103b. A throttle sensor 118 that detects the degree TVO, a water temperature sensor 119 that detects the coolant temperature of the engine 101, a cam sensor 132 that extracts a rotation signal from the intake side camshaft 134, and the like are provided.
[0022]
The ECU 114 calculates the engine speed Ne 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 VTC 113 includes a camshaft 134, a drive plate 2, an assembly angle adjustment mechanism 4, an actuator 15, and a VTC cover 6.
[0023]
The drive plate 2 is a member that rotates when rotation is transmitted from the engine 101 (crankshaft 120), and the assembly angle adjusting mechanism 4 changes the assembly angle between the camshaft 134 and the drive plate 2. It is a mechanism and is actuated by an actuating device 15.
The VTC cover 6 is a cover that is attached over the front end of a cylinder head and a rocker cover (not shown) and covers the front surface of the drive plate 2 and the assembly angle adjusting mechanism 4 and its peripheral area.
[0024]
A spacer 8 is fitted to the front end portion (left side in FIG. 2) of the camshaft 134, and the rotation of the spacer 8 is restricted by a pin 80 that passes through the flange portion 134f of the camshaft 134.
The camshaft 134 is formed with a plurality of oil supply holes 134r extending in the radial direction.
[0025]
As shown in FIG. 3, the spacer 8 includes a disc-shaped locking flange 8a, a circular pipe portion 8b extending in the axial direction from the front end surface of the locking flange 8a, and a front end surface of the locking flange 8a. A shaft support portion 8d is formed that extends in three directions in the outer diameter direction from the proximal end side of the circular tube portion 8b and is formed with a press-fit hole 8c parallel to the axial direction.
The shaft support portion 8d and the press-fitting hole 8c are arranged at 120 ° intervals in the circumferential direction as shown in FIG.
[0026]
The spacer 8 is formed with an oil supply hole 8r that supplies oil in a radial direction.
The drive plate 2 is formed in a disk shape with a through hole 2a formed in the center, and is assembled to the spacer 8 so as to be relatively rotatable with its axial displacement restricted by a locking flange 8a. ing.
[0027]
As shown in FIG. 3, the drive plate 2 is formed with a timing sprocket 3 on the outer periphery of the rear portion thereof, in which rotation 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 connecting the through hole 2a and the outer periphery, and the guide groove 2g is similar to the shaft support portion 8d. It arrange | positions every 120 degrees in the circumferential direction.
[0028]
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 rotator is constituted by the camshaft 134 and the spacer 8, and the drive rotator is constituted by the drive plate 2 including the timing sprocket 3.
[0029]
The assembly angle adjusting mechanism 4 is disposed on the front end side of the camshaft 134 and the drive plate 2 and changes the assembly relative angle between the camshaft 134 and the drive plate 2.
As shown in FIG. 3, the assembly angle adjusting mechanism 4 has three link arms 14.
[0030]
Each link arm 14 is provided with a cylindrical portion 14a as a slide portion at the distal end portion, and an arm portion 14b extending from the cylindrical portion 14a in the outer diameter direction.
An accommodation 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.
[0031]
The link arm 14 is attached so as to be rotatable about the rotation pin 81 by attaching the rotation hole 14 to the rotation pin 81 tightly press-fitted into the press-fitting hole 8 c of the spacer 8.
On the other hand, the cylindrical portion 14 a of the link arm 14 is inserted into a guide groove 2 g as a radial guide of the drive plate 2 and attached to the drive plate 2 so as to be movable (slidable) in the radial direction.
[0032]
In the above configuration, when the cylindrical portion 14a receives an external force and slides and moves in the radial direction along the guide groove 2g, the rotation pin 81 corresponds to the radial displacement amount of the cylindrical portion 14a by the link action by the link arm 14. The camshaft 134 is rotated relative to the drive plate 2 by the displacement of the rotation pin 81.
[0033]
4 and 5 show the operation of the assembly angle adjusting mechanism 4. When the cylindrical portion 14a is disposed on the outer peripheral side of the drive plate 2 in the guide groove 2g, as shown in FIG. The end rotation pin 81 is pulled to a position close to the guide groove 2g, and this position is the most retarded position.
On the other hand, as shown in FIG. 5, when the cylindrical portion 14a is disposed on the inner peripheral side of the drive plate 2 in the guide groove 2g, the rotation pin 81 is pushed in the circumferential direction and separated from the guide groove 2g. This position is the most advanced position.
[0034]
Movement of the cylindrical portion 14a in the radial direction in the assembly angle adjusting mechanism 4 is performed by the operating device 15, and the operating device 15 includes an operation converting mechanism 40 and an acceleration / deceleration mechanism 41.
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 so as to face the front surface of the drive plate 2 and the rotation of the guide plate 24. Is converted into a radial displacement of the cylindrical portion 14 a in the link arm 14.
[0035]
The guide plate 24 is supported on the outer periphery of the circular pipe portion 8 b of the spacer 8 through a metal bush 23 so as to be relatively rotatable.
Further, a spiral guide groove 28 is formed on the rear surface of the guide plate 24 as a spiral guide having a substantially semicircular cross section and being displaced in the radial direction in accordance with the displacement in the circumferential direction. The oil supply hole 24r for supplying oil is formed so as to penetrate in the front-rear direction.
[0036]
The sphere 22 is engaged with the spiral guide groove 28.
That is, the receiving hole 14c provided in the cylindrical portion 14a of the link arm 14 has a disk-like support panel 22a, a coil spring 22b, a retainer 22c, and a ball 22 as shown in FIGS. Are inserted in order.
The retainer 22c is formed with a flange-like support recess 22d that supports the ball 22 in a protruding state at the front end, and a flange 22f on the outer periphery of which the coil spring 22b is seated.
[0037]
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 engage in the vertical direction. In addition, relative movement is possible in the extending direction of the spiral guide groove 28.
Further, as shown in FIGS. 4 and 5, the spiral guide groove 28 is formed so as to gradually decrease in diameter along the rotation direction R of the drive plate 2.
[0038]
Therefore, when the guide plate 24 rotates relative to the drive plate 2 in the rotation direction R in a state where the sphere 22 is engaged with the spiral guide groove 28, the operation conversion mechanism 40 causes the sphere 22 to become the spiral guide groove. The cylindrical portion 14a as a slide portion moves in the radial direction along the spiral shape 28, thereby moving in the outer diameter direction shown in FIG. 4, and the rotation pin 81 connected to the link arm 14 is guided by the guide groove. The camshaft 134 is attracted to approach 2 g, and moves in the retarding direction.
[0039]
Conversely, 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. 5, and the rotation pin 81 connected to the link arm 14 is pushed away from the guide groove 2g. In this case, the camshaft 134 advances. Move in the angular direction.
[0040]
Next, the acceleration / deceleration mechanism 41 will be described in detail.
The acceleration / deceleration mechanism 41 accelerates and decelerates the guide plate 24 with respect to the drive plate 2, that is, moves (accelerates) the guide plate 24 in the rotational direction R with respect to the drive plate 2, 24 is moved (decelerated) with respect to the drive plate 2 in the direction opposite to the rotation direction R, and includes a planetary gear mechanism 25, a first electromagnetic brake 26, and a second electromagnetic brake 27.
[0041]
The planetary gear mechanism 25 includes a sun gear 30, a ring gear 31, and a planetary gear 33 meshed with both gears 30 and 31.
As shown in FIGS. 2 and 3, the sun gear 30 is integrally formed on the inner periphery on the front side of the guide plate 24.
The planetary gear 33 is rotatably supported by a carrier plate 32 fixed to the front end portion of the spacer 8.
[0042]
The ring gear 31 is formed on the inner periphery of an annular rotator 34 that is rotatably supported outside the carrier plate 32.
The carrier plate 32 is fitted to the front end portion of the spacer 8 and is fixed to the camshaft 134 through the bolt 9 with the washer 37 in contact with the front end portion.
[0043]
A braking plate 35 having a braking surface 35b facing forward is screwed to the front end surface of the rotating body 34.
A brake 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.
[0044]
Therefore, if the planetary gear 33 revolves together with the carrier plate 32 without the planetary gear 33 rotating, the sun gear 30 and the ring gear 31 are in a free state when the first electromagnetic brake 26 and the second electromagnetic brake 27 are inactive. At the same speed.
When only the first electromagnetic brake 26 is braked from this state, the guide plate 24 is rotated relative to the carrier plate 32 (with respect to the camshaft 134) in a direction (opposite to the R direction in FIGS. 4 and 5). Then, the drive plate 2 and the camshaft 134 are relatively displaced in the advance direction shown in FIG.
[0045]
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 planetary gear 33 rotates as the ring gear 31 rotates relative to the carrier plate 32 in the delay direction. The rotation speeds up the sun gear 30, the guide plate 24 rotates relative to the drive plate 2 in the rotational direction R side, and the drive plate 2 and the camshaft 134 rotate relative to each other in the retard direction shown in FIG. Become.
[0046]
In the present 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 disposed in an inner and outer double so as to face the braking surfaces 36b and 35b of the braking plates 36 and 35, respectively, and pins 26p, The circular pipe members 26r and 27r are supported in a floating state in which only the rotation is restricted by 27p.
[0047]
These circular pipe members 26r and 27r accommodate coils 26c and 27c, and are fitted with friction materials 26b and 27b that are pressed against the braking surfaces 35b and 36b when the coils 26c and 27c are energized. .
Further, each of the circular pipe members 26r, 27r and each of the brake plates 35, 36 are formed of a magnetic material such as iron in order to form a magnetic field when the coils 26c, 27c are energized.
[0048]
On the other hand, the VTC cover 6 does not cause magnetic flux leakage when energized, and the friction members 26b and 27b are made permanent magnets to prevent sticking to the brake plates 35 and 36 when de-energized. Further, it is made of a nonmagnetic material such as aluminum.
The relative rotation of the guide plate 24 provided with the sun gear 30 as the output element of the planetary gear mechanism 25 and the drive plate 2 is regulated by the assembly angle stopper 60 at the most retarded position and the most advanced position. It has become.
[0049]
Further, in the planetary gear mechanism 25, a planetary gear stopper 90 is provided between the brake plate 35 provided integrally with the ring gear 31 and the carrier plate 32.
By the way, the operation conversion mechanism 40 described above is configured so that the position of the cylindrical portion 14a of the link arm 14 is maintained and the relative assembly position between the drive plate 2 and the camshaft 134 does not vary. The configuration will be described.
[0050]
Drive torque is transmitted from the drive plate 2 to the camshaft 134 via the link arm 14 and the spacer 8, but due to a reaction force from the engine valve (intake valve 105) from the camshaft 134 to the link arm 14. The fluctuation torque of the camshaft 134 is input as a force F in the direction connecting the pivot pins 81 to the pivot points at both ends of the link arm 14.
[0051]
The cylindrical portion 14a of the link arm 14 is guided in the radial direction along a guide groove 2g as a radial guide, and a sphere 22 protruding from the cylindrical portion 14a to the front surface engages with the spiral guide groove 28. Therefore, the force F input via each link arm 14 is supported by the left and right walls of the guide groove 2 g and the spiral guide groove 28 of the guide plate 24.
[0052]
Accordingly, the force F input to the link arm 14 is decomposed into two component forces FA and FB orthogonal to each other. These component forces FA and FB are separated from the outer peripheral wall of the spiral guide structure 28 and the guide. The cylindrical portion 14a of the link arm 14 is prevented from moving along the guide groove 2g in a direction substantially perpendicular to one wall of the groove 2g, thereby preventing the link arm 14 from rotating. Is done.
[0053]
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, the link is basically performed without continuously applying the braking force. The position of the arm 14 can be maintained, that is, the rotational phase of the drive plate 2 and the camshaft 134 can be maintained as it is.
The force F is not limited to acting in the outer diameter direction, and may act in the opposite inner diameter direction. At this time, the component forces FA and FB are the walls on the inner peripheral side of the spiral guide groove 28. And the other side of the guide structure 2g are received in a substantially right angle direction.
[0054]
Hereinafter, the operation of the variable valve timing mechanism VTC 113 will be described.
When the rotational phase of the crankshaft and the camshaft 134 is controlled to the retard side, the second electromagnetic brake 27 is energized.
When the second electromagnetic brake 27 is energized, the friction material 27b of the second electromagnetic brake 27 is brought into frictional contact with the braking plate 35, the braking force is applied to the ring gear 31 of the planetary gear mechanism 25, and the sun gear is rotated as the timing sprocket 3 rotates. 30 is rotated at an increased speed.
[0055]
Due to the accelerated rotation of the sun gear 30, the guide plate 24 is rotated in the rotational direction R with respect to the drive plate 2, and accordingly, the ball 22 supported by the link arm 14 is moved to the outer peripheral side of the spiral guide groove 28. Moving.
The movement toward the retard side is regulated by the assembly angle stopper 60 at the most retarded position shown in FIG.
[0056]
Further, as described above, when the rotation of the ring gear 31 is braked by the second electromagnetic brake 27, the braking is performed while allowing a predetermined amount of rotation instead of instantaneously restricting the rotation. Then, the rotation of the ring gear 31 is regulated by the planetary gear stopper 90.
On the other hand, when the assembly angle of the camshaft 134 is displaced in the advance direction, the first brake 26 is energized.
[0057]
As a result, a braking force acts on the guide plate 24, the guide plate 24 rotates in the direction opposite to the rotation direction R with respect to the drive plate 2, and the assembly angle of the camshaft 134 is displaced to the advance side. .
This movement toward the advance side is regulated by the assembly angle stopper 60 at the most advanced position shown in FIG.
Further, when the rotation of the guide plate 24 is restricted, the planetary gear 33 rotates and the ring gear 31 rotates at an increased speed. When the rotation amount reaches a predetermined amount, the planetary gear stopper 90 restricts the rotation.
[0058]
The ECU 114 sets a target advance value of the camshaft 134 with respect to the crankshaft 120, and feedback-controls energization to the first electromagnetic brake 26 and the second electromagnetic brake 27 based on the target advance value. Details of the feedback control will be described with reference to the block diagram of FIG.
In FIG. 6, the advance value feedback control unit (rotation phase feedback control unit) 201 includes a target advance value (target rotation phase) set based on engine operating conditions (engine load, engine speed, etc.), and The actual advance value (actual rotational phase) detected from the detection signal of the crank angle sensor 117 and the detection signal of the cam sensor 132 is input.
[0059]
The advance value feedback control unit 201 calculates target drive currents for the electromagnetic brakes 26 and 27 based on the deviation between the target advance value and the actual advance value.
The calculation of the target drive current based on the deviation can be performed by proportional / integral / derivative control, and sliding mode control can be used.
[0060]
Further, the target drive current indicates that the current to be applied to the first electromagnetic brake 26 based on the advance angle request is indicated by plus, and the current to be applied to the second electromagnetic brake 27 based on the delay angle request is indicated by minus.
The actual advance value is detected, for example, as an angle from a reference crank angle position obtained from the detection signal of the crank angle sensor 117 to a reference cam angle position obtained from the detection signal of the cam sensor 132.
[0061]
The target drive current is output to the advance / retard angle separation unit 202, and it is determined which of the electromagnetic brakes 26 and 27 should be driven based on the plus / minus of the target drive current, and the target is determined based on the determination result. The drive current is output to one of the current feedback control units 203A and 203B.
That is, at the time of advance angle request in which the target drive current is positive, the target drive current calculated by the advance angle value feedback control unit 201 is output to the advance angle side current feedback control unit 203A, and the retard angle side current feedback control unit The target drive current of 203B is set to 0.
[0062]
On the other hand, at the time of a delay request in which the target drive current is negative, the target drive current calculated by the advance value feedback control unit 201 is output to the current feedback control unit 203B on the retard side, and the current feedback control unit on the advance side The target drive current of 203A is set to 0.
The current feedback control unit 203A (drive current feedback control unit) is configured to detect a detection result of a current detection circuit 204A (drive current detection unit) that detects a drive current actually flowing in the coil of the electromagnetic brake 26, a target drive current, On the basis of this deviation, the duty ratio when the average applied voltage is controlled by controlling on / off of energization to the electromagnetic brake 26 at a high frequency is calculated, and the control signal of the duty ratio is used to control the energization to the electromagnetic brake 26. Output to the switching element (transistor).
[0063]
Similarly, the current feedback control unit 203B (drive current feedback control unit) detects the detection result of the current detection circuit 204B (drive current detection unit) that detects the drive current actually flowing in the coil of the electromagnetic brake 27, and the target. Based on the deviation from the drive current, the duty ratio for controlling the average applied voltage by controlling on / off of energization to the electromagnetic brake 27 at a high frequency is calculated, and a control signal for the duty ratio is supplied to the electromagnetic brake 27. Output to a switching element (transistor) that controls energization.
[0064]
In the calculation of the duty ratio based on the deviation of the drive current, sliding mode control can be used in addition to proportional / integral / derivative control.
According to the above configuration, even if the coil temperature of the electromagnetic brakes 26 and 27 changes and the correlation between the duty ratio and the drive current changes, the target drive current is caused to flow through the coils of the electromagnetic brakes 26 and 27, Torque can be generated, and even if the temperature characteristics of the electromagnetic brakes 26 and 27 are different by detecting the drive current for each of the electromagnetic brakes 26 and 27 and individually feedback controlling the duty ratio, The drive currents of the electromagnetic brakes 26 and 27 can be matched with the target.
[0065]
Therefore, even if the temperature characteristics of the electromagnetic brakes 26 and 27 differ depending on the temperature environment and the amount of heat generation, the required torque can be generated in both the advance angle and the retard angle. The valve timing can be feedback controlled with desired response in both directions of the corners.
In the above embodiment, the spiral radial link type variable valve timing mechanism having the structure in which the guide plate on which the spiral guide is formed is relatively rotated in the advance direction and the retard direction by two electromagnetic brakes is targeted. It is not limited to the radial link type, and any variable valve timing mechanism configured to change the rotational phase of the camshaft relative to the crankshaft in the advance angle direction and the retard angle direction with the braking force of two electromagnetic brakes is the same. It is possible to obtain the same effect by applying drive current feedback control.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an internal combustion engine in 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.
4 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.
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 block diagram showing valve timing feedback control.
[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 ... 1st electromagnetic brake
27 ... Second electromagnetic brake
28 ... spiral guide groove
30 ... Sungear
31 ... Ring gear
32 ... Carrier plate
33 ... Planetary Gear
35 ... Brake plate
36 ... Brake plate
40. Action conversion mechanism
41 ... Increase / decrease 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

Claims (3)

A variable valve that changes the valve timing of the engine valve (105) by changing the rotational phase of the camshaft (134) relative to the crankshaft (120) of the internal combustion engine (101) by the braking force of the electromagnetic brake (26, 27). The timing mechanism (113) includes first and second electromagnetic brakes (26, 27), and the first electromagnetic brake (26) is operated to advance the rotation phase to change the second phase. In the variable valve timing mechanism (113) that changes the rotational phase by lagging by operating the electromagnetic brake (27) ,
Rotation phase feedback for setting the target drive current of the first electromagnetic brake (26) and the target drive current of the second electromagnetic brake (27) based on the target value of the rotation phase and the actual rotation phase, respectively. A control unit (201);
A first drive current detector (204A) for detecting a drive current actually flowing in the coil of the first electromagnetic brake (26);
A second drive current detector (204B) for detecting a drive current actually flowing in the coil of the second electromagnetic brake (27);
In order to make the drive current detected by the first drive current detector (204A) coincide with the target drive current of the first electromagnetic brake (26) set by the rotational phase feedback controller (201), A first drive current feedback control unit (203A) that feedback-controls a control amount of the drive current of the first electromagnetic brake (26);
In order to make the drive current detected by the second drive current detector (204B) coincide with the target drive current of the second electromagnetic brake (27) set by the rotational phase feedback controller (201), A second drive current feedback control unit (203B) that feedback-controls the control amount of the drive current of the second electromagnetic brake (27);
A control apparatus for a variable valve timing mechanism, comprising: The variable valve timing mechanism (113) is composed of a drive rotor (2) to which rotation is transmitted from the crankshaft (120) of the internal combustion engine (101) and a driven rotor (134, 8) on the camshaft side. Coaxially connected via an angle adjustment mechanism (4), and the assembly angle between the drive rotator (2) and the driven rotator (134, 8) is changed by the assembly angle adjustment mechanism (4). Thus, the valve timing of the engine valve (105) is changed, and the assembly angle adjusting mechanism (4) is configured such that the rotating part (14d) at one end has the driving rotating body (2) and the driven rotating body (134). , 8) and a radial guide provided at the other end of the drive rotator (2) and the driven rotator (134, 8). (2g) allows continuous sliding in the radial direction Is provided with a link arm (14) is, the sliding portion of the guide plate spiral guide for displacing (14a) in the radial direction (28) is formed (24), first and second electromagnetic brake (26, 27) relative to the drive rotator (2) in the deceleration direction and the speed increase direction, the position of the rotating portion (14d) is relatively displaced in the circumferential direction, and the drive rotator (2) and 2. The control device for a variable valve timing mechanism according to claim 1 , wherein an assembly angle with the driven rotor (134, 8) is changed. The guide plate (24) rotates via a planetary gear mechanism (25) having the carrier member (32) as an input element, one of the sun gear (30) and the ring gear (31) as an output element, and the other as a free element. The first electromagnetic brake (26) applies braking to the output element, and the second electromagnetic brake (27) applies braking to the free element. The control apparatus for a variable valve timing mechanism according to claim 2 .

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