JP4166644B2 - Valve timing control device for internal combustion engine - Google Patents

Description

  The present invention relates to a valve timing control device for an internal combustion engine that controls valve timing (opening / closing timing) of an intake valve of the internal combustion engine.

An example of a valve timing control device for an internal combustion engine is disclosed in Patent Document 1. In this apparatus, the valve timing of the intake valve at the time of engine start is a default position (most retarded position) that is mechanically determined by a stopper or the like.
JP-A-6-299876

  By the way, as described below, the default position in the conventional apparatus can be set only to satisfy both the startability requirement and the maximum output requirement to some extent.

  That is, in order to satisfy the engine startability requirement, the intake valve closing timing (IVC) at the time of starting is relatively advanced in order to prevent deterioration of ignitability due to a decrease in the actual compression ratio. Must be set. That is, from the startability request, it is desirable to set the default position to the advance side.

  On the other hand, in order to satisfy the maximum output requirement at the time of high rotation, it is necessary to set IVC to the retard side where the volumetric efficiency is increased by the action of inertia supercharging. That is, it is desirable to set the default position to the retard side from the highest output request.

  Thus, since the desired IVC is in the opposite direction between the startability request and the maximum output request, in the above-described conventional apparatus in which the valve timing of the intake valve at the time of engine start is the default position which is the most retarded position. Because this default position must be set based on the trade-off relationship between the startability requirement and the maximum output requirement, the engine performance can be satisfied even if both the startability requirement and the maximum output requirement can be satisfied to some extent. There was a problem that it was not possible to fully exhibit.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a valve timing control device for an internal combustion engine that can improve startability and output characteristics.

For this reason, the invention described in claim 1 has a variable valve timing mechanism configured to be operable from the engine start , and controls the valve timing of the intake valve to the target valve timing. The target valve timing of the intake valve during the period is set to be more advanced than the target valve timing after the complete explosion.

According to such a configuration, for example, the target valve timing on the relatively advanced side is set so that the valve timing is appropriate in terms of startability between the engine start and the complete explosion, and after the complete explosion, The target valve timing on the retard side is set so that the valve timing is appropriate in terms of combustion stability and output characteristics.

As a result, during the period from engine start to complete explosion, the target valve timing of the intake valve is set to a relatively advanced angle side, so that the actual compression ratio can be prevented from decreasing and startability (ignitability) can be improved. After the complete explosion, by controlling the target valve timing of the intake valve to the retard side, it is possible to reduce the return of exhaust gas to the intake air and stabilize the combustion. Moreover, volume efficiency can also be improved at the time of high rotation. Therefore, appropriate valve timing control can be realized according to each operation state of the engine, and the startability requirement, the combustion stability requirement immediately after the startup, and the maximum output requirement can be sufficiently satisfied .

Further, according to the first aspect of the present invention, a target valve closing timing of the intake valve is set as the target valve timing between the engine start and the complete explosion, and the valve closing timing of the intake valve is set to the target closing timing. The variable valve timing mechanism is controlled so that the valve timing is reached, and after the complete explosion, as the target valve timing, a target valve opening timing of the intake valve is set based on an operating state of the engine. The variable valve timing mechanism is controlled so that the valve opening timing becomes the target valve opening timing.

According to such a configuration, for example, the valve closing timing of the intake valve is controlled so as to ensure an appropriate actual compression ratio from the engine start to the complete explosion, and after the complete explosion, stable combustion is performed in each operation state. Further, the opening timing of the intake valve is controlled so as to ensure the maximum output and the like.

  As a result, the valve timing of the intake valve is controlled on the relatively advanced side from the start of the engine to the complete explosion, and is controlled on the relatively retarded side after the complete explosion, improving startability. Thus, it is possible to more effectively improve the combustion stability immediately after starting (at the time of low rotation) and the output characteristics at the time of high rotation.

According to a second aspect of the present invention, the target valve closing timing of the intake valve that is set between the engine start and the complete explosion is set according to the temperature of the engine.
As a result, during the period from engine start to complete explosion, the intake valve closing timing is set so that an appropriate actual compression ratio can be ensured according to the engine temperature, taking into account the influence of the engine temperature on ignitability. Be controlled.

  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 in the embodiment.

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

  The combustion exhaust is discharged from the combustion chamber 106 through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.

  The intake valve 105 and the exhaust valve 107 are driven to open and close by cams provided on the intake side camshaft 134 and the exhaust side camshaft 110, respectively. The intake side camshaft 134 includes a variable valve timing mechanism (VTC) 113. Is provided.

  The VTC 113 is a mechanism that changes the valve timing (opening / closing timing) of the intake valve 105 by changing the rotational phase of the intake camshaft 134 with respect to the crankshaft 120. In this embodiment, a spiral radial as described later is used. Adopts a link type variable valve timing mechanism.

  In this embodiment, the VTC 113 is provided only on the intake valve 105 side. However, the VTC 113 may be provided on the exhaust valve 107 side.

  In addition, an electromagnetic fuel injection valve 131 is provided in the intake port 130 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal from an engine control unit (ECU) 114, a predetermined value is set. The fuel adjusted to the pressure is injected toward the intake valve 105.

  The ECU 114 incorporating the microcomputer receives detection signals from various sensors, and controls the electronic control throttle 104, the VTC 113, and the fuel injection valve 131 by arithmetic processing based on the detection signals.

  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, and a reference crank angle signal at a reference rotational position every crank angle 180 ° from the crankshaft 120. A crank angle sensor 117 for taking out the REF and taking out a unit angle signal POS for each unit crank angle, a throttle sensor 118 for detecting the opening TVO of the throttle valve 103b, a water temperature sensor 119 for detecting the cooling water temperature Tw of the engine 101, the intake side A cam sensor 132 that extracts a cam signal CAM at a reference rotation position for each cam angle 90 ° (crank angle 180 °) from the camshaft 134, a voltage sensor 133 that detects a battery voltage VB, and the like are provided.

  The ECU 114 calculates the engine speed Ne based on the cycle of the reference crank angle signal REF or the number of unit angle signals POS generated per unit time.

  Next, the configuration of the VTC 113 will be described with reference to FIGS.

  The VTC 113 includes the (intake side) camshaft 134, the drive plate 2, the assembly angle adjustment mechanism 4, the actuator 15, and the VTC cover 6.

  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 mounted across the cylinder head (not shown) and the front end of the rocker cover, and covers the front surface of the drive plate 2 and the assembly angle adjusting mechanism 4 and its peripheral area.

  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.

  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.

  Note that the shaft support portion 8d and the press-fitting hole 8c are arranged at 120 ° intervals in the circumferential direction, as shown in FIG. 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.

  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.

  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.

  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.

  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.

  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 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.

  In such a 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 becomes the radial displacement amount of the cylindrical portion 14a by the link action by the link arm 14. The camshaft 134 moves relative to the drive plate 2 due to the displacement of the rotation pin 81.

  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.

  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.

  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 guide having a substantially semicircular cross section and being displaced in the radial direction in accordance with the displacement in the circumferential direction. An oil supply hole 24r for supplying oil is formed to penetrate in the front-rear direction.

  The sphere 22 is engaged with the spiral guide groove 28.

  That is, in the accommodation hole 14c provided in the cylindrical portion 14a of the link arm 14, as shown in FIGS. 2 and 3, a disk-shaped support panel 22a, a coil spring 22b (elastic body), a retainer 22c, , And a sphere 22 (spherical member) are sequentially inserted.

  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.

  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 reduce the diameter along the rotation direction R of the drive plate 2.

  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 the 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.

  Conversely, when the guide plate 24 rotates relative to the drive plate 2 in the direction opposite to the rotational 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.

  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.

  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.

  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.

  A braking plate 35 having a braking surface 35b facing forward is fixed to the front end surface of the rotating body 34 with a screw.

  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.

  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 rotates 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.

  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.

  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 a pin 26p, It has circular pipe members 26r and 27r supported in a floating state in which only rotation is restricted by 27p.

  The 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. .

  The circular pipe members 26r and 27r and the brake plates 35 and 36 are made of a magnetic material such as iron in order to form a magnetic field when the coils 26c and 27c are energized.

  On the other hand, the VTC cover 6 does not cause magnetic flux leakage when energized, and the friction materials 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. The most retarded angle position and the most advanced angle position regulated by the assembly angle stopper 60 are provided for defining the range in which the relative rotation is possible, and sets the valve timing and the like at the start. It is not intended for use.

  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.

  Driving torque is transmitted from the driving plate 2 to the camshaft 134 via the link arm 14 and the spacer 8, but the camshaft 134 is linked to the link arm 14 by the reaction force from the intake valve 105. The fluctuating torque is input as a force F in a direction connecting the pivot pins 81 to the pivot points at both ends of the link arm 14.

  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 forward from the cylindrical portion 14a is engaged 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.

  Therefore, 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.

  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 input to the link arm 14 is not limited to acting in the outer diameter direction but may act in the opposite inner diameter direction, but the component forces FA and FB at this time are spiral guides. The groove 28 is received in a substantially perpendicular direction to the inner peripheral wall of the groove 28 and the other side of the guide structure 2g.

  Here, the operation of the VTC 113 will be described.

  When the rotational phase of the crankshaft 120 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.

  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.

  Note that the movement toward the retard side is regulated by the assembly angle stopper 60 at the most retarded position shown in FIG.

  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 electromagnetic brake 26 is energized.

  As a result, a braking force acts on the guide plate 24, whereby the guide plate 24 rotates in the direction opposite to the rotation direction R with respect to the drive plate 2, and the camshaft 134 has an assembly angle on the advance side. Displaced.

  The 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.

  That is, in the VTC 113, the valve timing (opening / closing timing) of the intake valve 105 can be changed from the start of the engine by energizing the first electromagnetic brake 26 or the second electromagnetic brake 27 as an actuator.

  The ECU 114 sets the target advance angle value (target rotation phase) θtgi of the camshaft 134 relative to the crankshaft 120, that is, the valve timing based on the operating state of the engine (see FIG. 9), while the crank angle sensor The actual advance value (rotation phase) is detected by measuring the phase difference between the reference crank angle signal REF 117 and the cam signal CAM of the cam sensor 132 (see FIGS. 6 to 8). The energization of the first electromagnetic brake 26 and the second electromagnetic brake 27 (that is, the VTC 113) is feedback-controlled so as to coincide with the target advance value θtgi.

  6 to 8 are flowcharts for detecting the actual advance value.

  FIG. 6 is a flowchart for resetting the count value CPOS of the unit angle signal POS, which is executed when the reference crank signal REF is output from the crank angle sensor 117.

  In FIG. 6, the count value CPOS of the unit angle signal POS from the crank angle sensor 117 is set to 0 in S11.

  FIG. 7 is a flowchart for counting up the count value CPOS of the unit angle signal POS, which is executed when the unit angle signal POS is output from the crank angle sensor 117. In FIG. 7, the count value CPOS is incremented by 1 in S21.

  6 and 7, the count value CPOS is reset to 0 when the reference crank angle signal REF is generated, and becomes a value obtained by counting the number of subsequent unit angle signals POS generated.

  FIG. 8 is a flowchart for detecting the advance value, which is executed when the cam signal CAM is output from the cam sensor 132. In FIG. 8, in S31, the count value CPOS from the generation of the reference crank angle signal REF to the generation of the cam signal CAM is read.

  In S32, the advance value θdet of the camshaft 134 relative to the crankshaft 120 is detected based on the read count value CPOS.

  That is, in the present embodiment, the advance value θdet of the camshaft 134 with respect to the crankshaft 120 is detected and updated every time the cam signal CAM is output (every crank angle 180 °). If the advance value detected immediately before the engine is operating returns to a predetermined initial value when the engine is started or the engine is stopped, the initial value is It is an advance value.

  9 and 10 are a flowchart and a block diagram for setting the target advance value θtgi, which are executed every predetermined time (for example, 10 msec) after the start SW is turned on and the starter is operated.

  In S41, engine start determination is performed. In the present embodiment, it is assumed that the engine is started when the engine rotational speed Ne is equal to or higher than a predetermined start determination rotational speed Ne1 and / or when the battery voltage VB is equal to or higher than a predetermined start determination voltage VBs. judge. If the engine has been started, the process proceeds to S42, and if the engine has not been started, this flow ends.

  In S42, the complete explosion determination of the engine is performed. In the present embodiment, when the engine rotational speed Ne becomes equal to or higher than a predetermined complete explosion determination rotational speed Ne2 (> Ne1), it is determined that the engine has completely exploded. If the engine is completely detonated, the process proceeds to S43, and if it is not detonated, the process proceeds to S45.

  In S43, the target valve opening timing (target IVO) of the intake valve 105 is set based on the operating state (torque / rotation) of the engine in order to execute the valve timing control after the complete explosion. In the present embodiment, a map in which the target IVO is assigned for each operating state is created in advance, and the target IVO is set by referring to this map (see part A in FIG. 10).

  By setting the target IVO, as will be described later, the valve timing of the intake valve 105 set on the advance side from the engine start to the complete explosion is controlled to the retard side. As a result, the amount of valve overlap is reduced, and at low revolutions (such as when idling) immediately after a complete explosion, the exhaust air is not blown back into the intake air, and idling revolution (combustion) is stabilized. Can improve volumetric efficiency (maximum output is increased).

  It should be noted that the target IVO is set as described above in the valve timing control after the complete explosion because the valve overlap amount is determined by the valve opening timing (IVO) of the intake valve 105. This is for the purpose of control, and also for enabling control on the more retarded side.

  In S44, a target advance value (advance amount from the most retarded position at which the opening timing of the intake valve 105 becomes the target IVO) θtg1 is calculated from the target IVO (see B and C in FIG. 10). ), This flow ends. Thereby, the valve timing of the intake valve is controlled to the retard side after the complete explosion.

  On the other hand, in S45, the target valve closing timing (target IVC) of the intake valve 105 is set based on the engine coolant temperature Tw in order to execute the valve timing control from the engine start to the complete explosion. In the present embodiment, a target valve closing timing IVC corresponding to the engine coolant temperature Tw is created as a table in advance, and the target IVC is set by searching this table (see D section in FIG. 10). Thus, by setting the target IVC based on the engine coolant temperature Tw, an optimum actual compression ratio can be ensured in consideration of the influence of the engine temperature on the ignitability.

  Depending on the setting of the target IVC, the valve timing of the intake valve 105 from the engine start to the complete explosion is set. During this period, it is necessary to prevent deterioration of ignitability due to a decrease in the actual compression ratio. For this reason, it is not desirable to make the valve timing (valve closing timing) too retarded. Accordingly, the valve timing on the relatively advanced side is set here.

  Note that the reason why the target IVC is set as described above in the valve timing control from the engine start to the complete explosion is that the actual compression ratio varies depending on the valve closing timing (IVC) of the intake valve 105. This is because the IVC is accurately controlled so that the actual compression ratio required at the time of starting is obtained, and more advanced control is possible.

  Then, in S46, a target advance value (advance amount from the most retarded position at which the closing timing of the intake valve 105 becomes the target IVC) θtg2 is calculated from the target IVC (refer to portions E and F in FIG. 10). ), This flow ends. As a result, the valve timing of the intake valve 105 is controlled to a relatively advanced side during the period from engine start to complete explosion.

  As described above, in the present embodiment, the target IVC is set according to the engine coolant temperature Tw and the VTC 113 is controlled so as to be the target IVC during the period from the start of the engine to the complete explosion. While the valve timing of the valve 105 is controlled to be relatively advanced, the target IVO is set based on the operating state (torque / rotation) of the engine after the complete explosion, and the VTC 113 is controlled so as to be the target IVO. Thus, the valve timing of the intake valve 105 set to the advance side is controlled to the retard side.

  As described above, the VTC 113 operable from the engine start is adopted, and the VTC 113 (valve timing of the intake valve 105) is controlled separately by separating the period from the engine start to the complete explosion and after the complete explosion. Until the complete explosion is reached, the valve timing of the intake valve can be set to the advance side as compared with the conventional case, and the ignition performance can be improved and the startability requirement can be sufficiently satisfied. In addition, after the complete explosion, the valve timing of the intake valve is set to the retard side, so that combustion can be stabilized (idle rotation can be stabilized).

  And since there is no need to set the most retarded position of the closing timing of the intake valve 105 from the trade-off between the startability requirement and the maximum output requirement as in the prior art, as shown in FIG. The IVC can be controlled further to the retard side (shown by the solid line in FIG. 11: 75 degCA ABDC) than the conventional most retarded position (shown by the broken line in FIG. 11: 65 degCA ABDC), thereby improving the volume efficiency. Therefore, the maximum output requirement can be fully satisfied.

In the above, the target IVC is set according to the engine coolant temperature Tw from the engine start to the complete explosion, but is controlled to a constant advance position (a constant target IVC is set). You may do it. In this way, it is possible to obtain the same effect as that of the above embodiment while making the control simpler.

  In the present embodiment, a spiral radial link type variable valve timing mechanism is employed. However, a variable valve timing mechanism having another structure may be used as long as it is configured to be operable from the start of the engine.

1 is a system configuration diagram of an internal combustion engine in an embodiment. FIG. It is sectional drawing which shows the variable valve timing mechanism in embodiment. It is a disassembled perspective view of the said variable valve timing mechanism. It is AA sectional drawing of FIG. 2 which shows the action | operation of the principal part of the said variable valve timing mechanism. It is AA sectional drawing of FIG. 2 which shows the action | operation of the principal part of the said variable valve timing mechanism. It is a flowchart which shows the CPOS reset process for every reference | standard crank angle signal REF. It is a flowchart which shows the count-up process of CPOS for every unit angle signal POS. It is a flowchart which shows the detection process of the advance value (rotation phase) (theta) det for every cam signal CAM. It is a flowchart which shows the setting process of target advance angle value (theta) tg. It is a block diagram which shows the setting process of target advance value θtg. It is a figure which shows the effect (improvement of the maximum output) of this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 105 ... Intake valve, 113 ... Variable valve timing mechanism VTC, 114 ... Engine control unit, 117 ... Crank angle sensor, 120 ... Crankshaft, 132 ... Cam sensor, 134 ... Intake camshaft

Claims (2)

A valve timing control device for an internal combustion engine,
A variable valve timing mechanism configured to be operable from the start of the engine and changing the valve timing of the intake valve of the engine;
Valve timing detection means for detecting the valve timing of the intake valve;
Engine state detecting means for detecting the state of the engine;
Control means for setting the target valve timing and controlling the variable valve timing mechanism so that the valve timing of the intake valve becomes the target valve timing,
While the control means sets the target valve timing between the engine start and the complete explosion to the advance side than the target valve timing after the complete explosion ,
Between the engine start and the complete explosion, the target valve timing is set as the target valve closing timing of the intake valve, and the variable valve timing is set so that the valve closing timing of the intake valve becomes the target valve closing timing. Control mechanism,
After the complete explosion, the target valve timing is set so that the target valve opening timing of the intake valve is set based on the operating state of the engine, and the valve opening timing of the intake valve becomes the target valve opening timing. A valve timing control apparatus for an internal combustion engine, characterized by controlling a valve timing mechanism . 2. The valve timing control for an internal combustion engine according to claim 1, wherein the control means sets a target valve closing timing of the intake valve set between an engine start and a complete explosion in accordance with an engine temperature. apparatus.

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