JP2010053711A - Control device for internal combustion engine during deceleration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain an increase in torque before starting a fuel cut, in an internal combustion engine executing control for increasing intake negative pressure by increasing an effective opening of an intake valve in the fuel cut. <P>SOLUTION: After a fuel cut condition is realized, before starting the fuel cut, after delaying the opening-closing timing of an exhaust valve by a second variable valve train (VTC 113b), the effective opening of the intake valve is increased by a first variable valve train (VEL 112), and an increased in combustion pressure (torque) is restrained by residual gas by increasing a valve overlap quantity. and the opening-closing timing of the exhaust valve is returned to a lead angle side by the second variable valve train (VTC 113b) after starting the fuel cut, and the effective opening of the intake valve is returned to the reduction side by the first variable valve train (VEL 112) after fuel recovery. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for controlling a variable valve mechanism mounted on an internal combustion engine when an intake negative pressure is generated downstream of a throttle valve during deceleration.

Patent Document 1 includes a variable valve mechanism that can change the operating angle and lift amount of an intake valve. When a large deceleration is required during deceleration accompanied by a fuel cut, the throttle valve is closed and the operating angle of the intake valve is set. It is also disclosed that the intake negative pressure on the downstream side of the throttle valve is increased by increasing the lift amount.
In addition, it is required to secure the intake negative pressure at the time of deceleration for a brake assist device that uses the intake negative pressure as a drive source, other steam fuel purge control, blow-by gas control, and the like.
JP 2005-188284 A

By the way, in Patent Document 1, at the time of deceleration, the lift amount of the intake valve decreases to near the minimum in accordance with the accelerator closing operation, and then the lift amount increases in response to a request to increase the intake negative pressure. Until it is started, torque increases and drivability is impaired.
The present invention has been made paying attention to such a conventional problem, and an object thereof is to suppress an increase in torque while ensuring a negative intake pressure during deceleration.

  For this reason, the present invention increases the effective opening of the intake valve by the first variable valve mechanism that can change the effective opening of the intake valve before the fuel cut is performed at a predetermined deceleration accompanied by the fuel cut. The second variable valve mechanism with variable valve opening / closing timing is used to increase the valve overlap amount with the intake valve by shifting the opening / closing timing of the exhaust valve to the retard side.

With such a configuration, at the time of a predetermined deceleration accompanied by a fuel cut, after the effective opening of the intake valve is reduced according to the accelerator closing operation, the intake valve is controlled by the first variable valve mechanism in response to a request to increase the intake negative pressure. In this case, the opening / closing timing of the exhaust valve is retarded by the second variable valve mechanism, and the valve overlap amount with the intake valve increases.
As a result, the amount of residual gas in the cylinder increases until the fuel cut is executed, and the increase in combustion pressure can be suppressed and the increase in torque can be suppressed. After the start of the fuel cut, the intake air flow rate is increased by increasing the effective opening of the intake valve, so that the intake negative pressure on the downstream side of the closed throttle valve is increased and the feeling of deceleration is enhanced.

FIG. 1 is a system configuration diagram of an internal combustion engine for a vehicle according to an 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 a combustion chamber 106 is connected via the electronic control throttle 104 and the intake valve 105. Air is inhaled inside.
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.

On the intake valve 105 side, a variable valve event and lift (VEL) mechanism 112 that continuously varies the valve lift amount of the intake valve 105 together with the operating angle is provided. Here, in the variable valve mechanism VEL112 of the present embodiment, the valve lift amount and the valve operating angle are valve characteristics that correlate with the average opening, that is, the effective opening during the open period of the intake valve 105.
Further, on the intake valve 105 side, by changing the rotation phase of the intake camshaft with respect to the crankshaft 120, the VTC (Variable valve Timing) that continuously varies the center phase (opening / closing timing) of the operating angle of the intake valve 105 is changed. Control) mechanism 113a is provided.

On the other hand, on the exhaust valve 107 side, by changing the rotation phase of the exhaust camshaft 110 with respect to the crankshaft 120, a VTC (Variable valve) that continuously varies the center phase (opening / closing timing) of the operating angle of the exhaust valve 107 is provided. Timing Control) mechanism 113b is provided.
The VEL mechanism 112 on the intake valve side corresponds to a first variable valve mechanism, and the VTC mechanism 113b on the exhaust valve side corresponds to a second variable valve mechanism mechanism.

An engine control unit (ECU) 114 with a built-in microcomputer has a VEL mechanism 112 and a VTC mechanism so as to obtain a required intake air amount corresponding to the required torque and to obtain a required intake negative pressure at a predetermined deceleration. 113a, b and the electronic control throttle 104 are controlled.
The ECU 114 includes an air flow meter 115 that detects an intake air amount of the internal combustion engine 101, and an accelerator pedal sensor 116 that detects an accelerator opening (including an idle switch that detects an idle state below a predetermined accelerator opening). , A crank angle sensor 117 that extracts a unit angle signal POS for each unit crank angle from the crankshaft 120, a throttle sensor 118 that detects the opening TVO of the throttle valve 103b, a water temperature sensor 119 that detects the cooling water temperature of the internal combustion engine 101, and a cam Detection signals from a first cam sensor 132 and a second cam sensor 133 that extract the cam signal CAM and cam angle signal CAMA from the shaft and a vehicle speed sensor 134 that detects the vehicle speed are input.

  Here, the crank angle sensor 117 detects the detected portion provided at every 10 ° in the crank angle with respect to the rotating body that rotates integrally with the crankshaft 120, and as shown in FIG. The unit angle signal POS is output every 10 °, but the two detected angle portions POS are continuously output without providing the two detected portions continuously at the crank angle at two intervals of 180 °. Not to be.

The crank angle of 180 ° corresponds to the stroke phase difference between the cylinders in the four-cylinder engine of the present embodiment.
A portion where the unit angle signal POS is temporarily interrupted is detected based on the output period of the unit angle signal POS. For example, the unit angle signal POS output first after the unit angle signal POS is interrupted is used as a reference. A reference rotational position of the crankshaft 120 is detected.

The ECU 114 calculates the engine rotation speed by counting the detection cycle of the reference rotation position or the number of occurrences of the unit angle signal POS per predetermined time.
The crank angle sensor 117 may be configured to individually output a reference angle signal REF for each reference rotational position (every 180 °) of the crankshaft 120 and a unit angle signal POS with no omission.

Further, the first cam sensor 132 detects a detected portion provided in a rotating body that rotates integrally with the camshaft, and as shown in FIG. 18, the cam angle is 90 ° corresponding to a crank angle of 180 °. In addition, a cam signal (cylinder discrimination signal) CAM indicating the cylinder number (first cylinder to fourth cylinder) by the number of pulses is output.
Further, as shown in FIG. 19, the second cam sensors 133a and 133b are formed so that the radius of the rotating body 133a that rotates integrally with the camshaft continuously changes in the circumferential direction. As shown in FIG. 20, the output of the gap sensor 133b fixed facing the periphery is continuously changed by changing the distance (gap) between the gap sensor 133b and the periphery of the rotating bodies 133a, b by the rotation of the camshaft. Configured to change.

Here, since the relationship between the angular position of the camshaft and the gap is constant, as shown in FIG. 21, the output of the gap sensor 133b and the angular position of the camshaft have a certain correlation, and the gap The angular position of the camshaft can be detected from the output of the sensor 133b, and the output of the gap sensor 133b is the cam angle signal CAMA.
The intake port 130 upstream of the intake valve 105 of each cylinder is provided with an electromagnetic fuel injection valve 131. The fuel injection valve 131 is driven to open by an injection pulse signal from the ECU 114, and the injection pulse signal An amount of fuel proportional to the injection pulse width (valve opening time) is injected.

2 to 4 show the structure of the VEL mechanism 112 in detail.
The VEL mechanism 112 shown in FIGS. 2 to 4 includes a pair of intake valves 105, 105, a hollow camshaft 13 (drive shaft) rotatably supported by the cam bearing 14 of the cylinder head 11, and the camshaft Two eccentric cams 15 and 15 (drive cams), which are rotational cams supported by the shaft 13, a control shaft 16 rotatably supported by the same cam bearing 14 above the cam shaft 13, and the control shaft 16, a pair of rocker arms 18 and 18 that are swingably supported via a control cam 17, and a pair of independent lifters 19 and 19 disposed at the upper end of each intake valve 105 and 105 via a pair of valve lifters 19 and 19, respectively. The rocking cams 20 and 20 are provided.

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

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

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

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

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

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

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

  The control shaft 16 is configured to be rotationally driven by a DC servo motor (actuator) 121 within a predetermined rotational angle range limited by a stopper with the configuration shown in FIG. Is changed by the actuator 121 so that the valve lift amount and the valve operating angle of the intake valve 105 continuously change within a variable range between the maximum valve lift amount and the minimum valve lift amount limited by the stopper. (See FIG. 9).

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

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

As shown in FIG. 10, a potentiometer type angle sensor 127 for detecting the angle of the control shaft 16 is provided at the tip of the control shaft 16, and the actual angle detected by the angle sensor 127 is the target angle. The ECU 114 feedback-controls the DC servo motor 121 so as to match (a target valve lift amount equivalent value).
Next, the configuration of the VTC mechanism 113a (113b) will be described with reference to FIGS.

  As shown in FIG. 11, the VTC mechanism 113a (113b) is assembled to the camshaft 13 (110) and the front end portion of the camshaft 13 (110) so as to be relatively rotatable as required. A driving ring 303 (driving rotator) having a timing sprocket 302 linked to the crankshaft 120 via an outer periphery (not shown) and a front side of the driving ring 303 and the camshaft 13 (left side in FIG. 11). An assembly angle operation mechanism 304 that is disposed to operate the assembly angles of the both 303 and 301, and an operation force applying means 305 that is disposed further forward of the assembly angle operation mechanism 304 and drives the mechanism 304. And an assembly angle operating mechanism 304 and an operating force applying means 305 mounted across the cylinder head and the front surface of the head cover (not shown) of the internal combustion engine. And a, a VTC cover of FIG outside covering the surface and peripheral region.

The drive ring 303 is formed in a short shaft cylindrical shape having a step-like insertion hole 306, and this insertion hole 306 portion is connected to a front end portion of the camshaft 13 (110). ) In a rotatable manner.
As shown in FIG. 12, three radial grooves 308 (radial guides) having parallel side walls facing each other are provided on the front surface of the drive ring 303 (the surface opposite to the camshaft 13). It is formed so as to be along the substantially radial direction.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  The VTC mechanism 113 according to the present embodiment is configured as described above. When the excitation of the electromagnetic coil 324 of the hysteresis brake 320 is turned off, the intermediate rotating body 318 is moved against the drive ring 303 by the urging force of the mainspring spring 319. The maximum rotation angle in the engine rotation direction, the engagement pin 316 is regulated at a position where it abuts against the outer peripheral side end surface 315a of the spiral groove 315, and this position can be changed on the mechanism of the VTC mechanism 113. (See FIG. 12).

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

When the exciting current of the electromagnetic coil 324 is increased to increase the braking force, the engagement pin 316 is finally regulated at a position where it abuts against the inner peripheral side end surface 315b of the spiral groove 315, and this position is the VTC mechanism. This is the most advanced position of the rotational phase that can be changed on the mechanism 113 (see FIG. 14).
When the exciting current of the electromagnetic coil 324 is reduced from this state and the braking force is reduced, the intermediate rotating body 318 is rotated back in the forward direction by the urging force of the mainspring spring 319 and is linked by the induction of the engaging pin 316 by the spiral groove 315. 311 swings in the opposite direction, and the assembly angle of the drive ring 303 and the driven shaft member 307 is changed to the retard side.

  Thus, the rotational phase of the camshaft 13 relative to the crankshaft 120 that is varied by the VTC mechanism 113 (the central phase of the operating angle of the intake valve 105) controls the excitation current value of the electromagnetic coil 324 to control the hysteresis brake 320. It is arbitrarily changed by controlling the braking force, and the phase can be maintained by the balance between the force of the mainspring spring 319 and the braking force of the hysteresis brake 320.

The ECU 114 calculates the advance angle target of the rotation phase in the VTC mechanism 113, and feedback-controls the excitation current value of the electromagnetic coil 324 so that the actual rotation phase matches the advance angle target.
As described above, in the internal combustion engine including the VEL mechanism 112 having a variable effective opening determined by the operating angle and lift amount of the intake valve and the VTC mechanism 201 having a variable opening / closing timing, the following control is executed during deceleration.

FIG. 22 shows a flow of deceleration control in the first embodiment.
In step S1, detection signals (accelerator opening, idle switch, throttle opening, engine speed, vehicle speed, intake negative pressure, intake valve effective opening, exhaust valve opening / closing timing, etc.) from the various sensors are input. .
In step S2, it is determined whether a predetermined deceleration condition for executing fuel cut is satisfied. Specifically, as is well known, the determination is made based on whether the idle switch is turned on and the accelerator is released at a vehicle speed or engine speed higher than a predetermined value. Here, in this embodiment and the following embodiments, the intake negative pressure is strengthened when the fuel is cut.

  When it is determined in step S2 that a fuel cut request has occurred, the process proceeds to step S3, where a timer for measuring the elapsed time from the determination is started and the VTC 113b is driven to open / close the exhaust valve 107 ( The operating angle center phase is retarded to the target value. It is desirable that the control for retarding the target value is performed with a high response by increasing the control gain or the like, and converges to the target value as quickly as possible.

When the fuel cut condition is satisfied, the effective opening (operating angle and lift amount) of the intake valve 105 is reduced to the vicinity of the minimum opening by the VEL mechanism 112 according to the accelerator closing operation at the time of deceleration. 103b is also closed to the vicinity of the fully closed position (minimum opening) due to an intake negative pressure request described later.
In step S4, after the elapse of the delay time t0 until the opening / closing timing of the exhaust valve 107 is retarded to the target value, the process proceeds to step S5.

In step S5, the VEL mechanism 112 is driven to increase the effective opening of the intake valve 105 to a target value.
The target value of the effective opening of the intake valve 105 is determined by increasing the effective opening to the target value and increasing the intake air flow rate at the time of fuel cut (non-combustion). Can be increased to a size sufficient for a drive source of the brake assist device, and the speed of deceleration (increase in negative torque) can be increased by increasing the pumping loss.

On the other hand, the target value of the opening / closing timing of the exhaust valve 107 in step S3 is retarded to the target value to increase the valve overlap amount with the intake valve 105, whereby fuel cut is started. During the combustion period up to the time, the residual gas is increased and the combustion pressure is decreased, so that a sufficient torque increase suppressing effect can be obtained.
In step S6, it is determined whether fuel cut has been started. Specifically, after a fuel cut request is generated, the fuel cut is started in step S7 after a predetermined delay time t1 (> t0) has elapsed. In this way, the delay in fuel cut is caused by the delay in fuel injection amount due to the delay in reducing the air amount, the influence of wall flow fuel amount, etc. in the deceleration transient state when the fuel cut condition is satisfied. This is because the combustion pressure is maintained high, and if the fuel cut is performed in this state, the torque is drastically reduced and the drivability is impaired (see FIG. 23).

  If it is determined that the fuel cut has been started, the process proceeds to step S8, where the VTC mechanism 113b is driven to start the control for returning the opening / closing timing of the exhaust valve 107 from the retarded angle side to the advanced angle side. Specifically, the opening / closing timing of the exhaust valve 107 before the start of the retard control when the fuel cut condition is established in step S2 is set as a new target value, and control is performed to return to this target value. Although the return speed to the target value may be slower than that during the retard control, the valve overlap amount is reduced by the return operation to the advance side, the intake air flow rate during fuel cut increases, and intake negative flow is increased. The pressure increases. That is, if the return speed is increased, the increase in intake negative pressure is accelerated, while the torque change speed increases. Therefore, the return speed may be set in consideration of such balance.

In step S9, it is determined whether or not the fuel cut has been completed and the fuel recovery (resumption of fuel supply) has been switched to.
If it is determined that the fuel recovery has been switched, the process proceeds to step S10, where the VEL 112 is driven, and the control to decrease and return the effective opening of the intake valve 105 is started. Specifically, the target value may be set by searching the map based on the operating state at the time of fuel recovery, but a value near the minimum opening before increasing the effective opening is set as the target value. Also good.

According to the above embodiment, as shown in the time chart of FIG. 23, after the fuel cut condition is satisfied at the time of deceleration, the opening / closing timing of the exhaust valve 107 is controlled to the retard side by the VTC 113b, and then the intake valve 105 of the intake valve 105 is controlled by the VEL 112. The effective opening is controlled to increase.
As a result, the effective opening of the intake valve 105 is increased and the fuel injection amount is increased until the fuel cut is started. However, the closing timing EVC of the exhaust valve 107 is delayed and the intake valve 105 opening timing IVO to EVC. As a result of increasing the valve overlap amount and increasing the residual gas amount, it is possible to suppress an increase in combustion pressure and consequently an increase in torque, and to prevent deterioration in operability.

In particular, in this embodiment, since the effective opening degree increase control of the intake valve 105 by the VELL 112 is started after the end of the retard control of the VTC 113b, the torque increase can be sufficiently suppressed from the initial stage.
However, if the response speed of the retard control of the opening / closing timing of the exhaust valve 107 by the VTC 113b is sufficiently increased while the rise of the effective opening increase of the intake valve 105 by the VEL 112 is moderated, the control of the VTC 113b and the VEL 112 is performed. Even if started almost simultaneously, an increase in torque can be suppressed from the beginning. In this manner, by bringing the disclosure timings of the two controls closer, the amount of deviation from the optimum value determined by the correlation between the opening / closing timing of the exhaust valve 107 and the effective opening of the intake valve 105 can be reduced. And maintain good flammability. In addition, when the opening / closing timing of the exhaust valve 107 is being retarded, or when the valve is re-advanced within a short period of time after the retard control is completed, the effective opening of the intake valve 105 has already increased. Since the control is started, the advance angle control can be followed with a high response, and the drivability can be improved.

  In addition, while suppressing the increase in torque until the start of fuel cut as described above, after the start of fuel cut, the effective opening degree of the intake valve 105 is increased to increase the intake air flow rate, so that it is in the vicinity of the fully closed state. The intake negative pressure on the downstream side of the throttle valve can be increased to a sufficient level for a drive source of the brake assist device, and the feeling of deceleration (increase in negative torque) can be increased by increasing the pumping loss.

Furthermore, since the increase in torque before the fuel cut can be suppressed, the torque step at the time of the torque reduction at the start of the fuel cut can be reduced, and the drivability can be improved.
In the present embodiment, as shown by the solid line in FIG. 23, the valve overlap amount is reduced by releasing the retard control of the opening / closing timing of the exhaust valve 107 immediately after the start of the fuel cut and returning it to the advance side. As a result, the intake air flow rate is increased and the intake negative pressure can be further increased.

  FIG. 24 shows a flow of control during deceleration according to the second embodiment. The difference from the first embodiment is that the ignition timing is corrected during the combustion period after the fuel cut condition is established and before the fuel cut is started. That is, in general engine models, even if the valve overlap amount is increased and the residual gas amount is increased, the basic value without correction of the ignition timing (a map in which control for increasing the valve overlap amount is not performed) is performed. (A value set by a search from the above) and the like, it is possible to achieve both prevention of misfire and reduction of the HC emission amount, and furthermore, both can be achieved even if the ignition timing is corrected to the retard side. Therefore, in the present embodiment, in order to prevent misfire, in step S5 ′, a known misfire diagnosis factor is used to correct to the retard side within the range not exceeding the misfire limit.

With this ignition timing retardation correction, it is possible to increase the intake negative pressure to the maximum while preventing misfire, and at the same time, reduce the engine torque to enhance the engine braking action and obtain a strong feeling of deceleration.
However, depending on the engine model, etc., if the valve overlap amount is increased and the residual gas amount is increased, the combustibility is lowered, and if there is a concern about the occurrence of misfire or the increase in the HC emission amount, conversely, The ignition timing can be corrected to the advance side so that misfire prevention and HC emission reduction can be achieved at the same time.

FIG. 25 shows a third embodiment in which the retard control of the exhaust valve opening / closing timing by the VTC 113b is canceled at the time of fuel recovery in the flowcharts of FIGS.
In FIG. 25, when the fuel recovery is determined in step S11, the retard control of the opening / closing timing of the exhaust valve 107 by the VTC 113b is canceled in step S12, the return control to the advance side is started, and at the same time, the intake by the VEL 112 is started. The increase control of the effective opening of the valve 105 is canceled, and the effective opening decrease control is started.

  That is, the effective opening of the intake valve 105 by the VEL 112 is returned to the decreasing side in accordance with the fuel recovery, the intake air amount is decreased, and the recovered fuel amount is set to be small in accordance with the intake air amount, thereby recovering the fuel. The torque step at the time can be suppressed. On the other hand, by performing the control for advancing the exhaust valve opening / closing timing by the VTC 113b in accordance with the control for reducing the effective opening of the intake valve 105, stable combustibility after fuel recovery can be ensured.

  Further, the control for returning the effective opening of the intake valve 105 to the decreasing side is performed with a high response, and the torque step during fuel recovery can be suppressed to a smaller extent as it is completed in a shorter time. At the same time, the advance control of the exhaust valve opening / closing timing by the VTC 113b is similarly performed with high response and completed in a short time, so that stable combustibility during fuel recovery can be ensured.

  In the present embodiment, during the fuel cut, the opening / closing timing of the exhaust valve 107 is maintained on the retard side to increase the valve overlap amount, so that the intake negative pressure is small compared to the first embodiment, Negative torque (absolute value) is small. On the other hand, by simultaneously reducing the effective opening of the intake valve 105 and returning the exhaust valve opening / closing timing to the advance side simultaneously (completed in a short time) at the same time as the fuel recovery, good combustion at the time of fuel recovery The increase in torque can be kept to a minimum while ensuring the performance. Therefore, the torque step at the time of fuel recovery can be further reduced.

FIG. 26 shows a fourth embodiment in which the retard control of the exhaust valve opening / closing timing by the VTC 113b is canceled when the intake negative pressure request is canceled after the fuel recovery (idle state) in the flowcharts of FIGS. Indicates.
In FIG. 26, when it is determined in step S21 that the intake negative pressure request after the fuel recovery is canceled (idle state when the vehicle speed is substantially zero), the opening / closing timing of the exhaust valve 107 by the VTC 113b is retarded in step S22. The control is canceled and the return control to the advance side is started. At the same time, the increase control of the effective opening degree of the intake valve 105 by the VEL 112 is canceled and the effective opening decrease control is started.

In this case, after recovering the fuel and before returning to the idle state, the effective opening of the intake valve 105 is gradually decreased from the VEL 112 by searching from the map based on the operating state, while the effective opening is decreased. In accordance with the speed, the opening / closing timing of the exhaust valve 107 by the VTC 113b is also gradually returned to the advance side.
In this embodiment, as long as there is a request for intake negative pressure until the engine returns to the idle state after fuel recovery, the effective opening of the intake valve 105 is increased and the opening / closing timing of the exhaust valve 107 is maintained on the retard side. Thus, the intake negative pressure downstream of the throttle valve can be kept large by increasing the intake air flow rate while suppressing the increase in combustion pressure and suppressing the increase in torque after fuel recovery, as before the start of fuel cut. .

1 is a system configuration diagram of an internal combustion engine in an embodiment. Sectional drawing (AA sectional drawing of FIG. 3) which shows a VEL (Variable valve Event and Lift) mechanism. The side view of the said VEL mechanism. The top view of the said VEL mechanism. The perspective view which shows the eccentric cam used for the said VEL mechanism. Sectional drawing which shows the effect | action at the time of the low lift of the said VEL mechanism (BB sectional drawing of FIG. 3). Sectional drawing which shows the effect | action at the time of the high lift of the said VEL mechanism (BB sectional drawing of FIG. 3). The valve lift characteristic view corresponding to the base end surface and cam surface of the swing cam in the VEL mechanism. FIG. 6 is a characteristic diagram of valve timing and valve lift of the VEL mechanism. The perspective view which shows the rotational drive mechanism of the control shaft in the said VEL mechanism. Sectional drawing which shows a VTC (Variable valve Timing Control) mechanism. Sectional drawing which follows the AA line of FIG. Sectional drawing which follows the BB line of FIG. Sectional drawing similar to FIG. 12 which shows the operating state of the said VTC mechanism. The graph which shows the magnetic flux density-magnetic field characteristic of a hysteresis material. FIG. 14 is a partial enlarged cross-sectional view of FIG. 13. It is the schematic diagram which expand | deployed the components of FIG. 16 linearly, and is a figure which shows the flow of the magnetic flux in the initial state (a) and when a hysteresis ring rotates (b). The timing chart which shows the output signal of a crank angle sensor and a 1st cam sensor. The figure which shows the structure of a 2nd cam sensor. The diagram which shows the correlation with a gap and a gap sensor output. The diagram which shows the correlation with the angle position of a camshaft, and a gap sensor output. The flowchart which shows the deceleration time control which concerns on 1st Embodiment. The time chart which shows the mode of the change of the various state quantity in the deceleration time control which concerns on 1st Embodiment. The flowchart which shows the deceleration time control which concerns on 2nd Embodiment. The flowchart which shows the principal part of the control at the time of deceleration which concerns on 3rd Embodiment. The flowchart which shows the principal part of the control at the time of deceleration which concerns on 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 13 ... Camshaft, 16 ... Control shaft, 101 ... Internal combustion engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 112 ... VEL mechanism (variable valve mechanism), 113 ... VTC mechanism (variable valve timing mechanism), 114 ... Engine control unit (ECU), 117 ... crank angle sensor, 120 ... crankshaft, 121 ... DC servo motor, 127 ... angle sensor, 132 ... first cam sensor, 133 ... second cam sensor, 133b ... gap sensor

Claims (8)

An internal combustion engine comprising a first variable valve mechanism that can vary the effective opening of an intake valve, and a second variable valve mechanism that can vary the opening and closing timing of an exhaust valve,
During a predetermined deceleration accompanied by a fuel cut, the first variable valve mechanism is driven to increase the effective opening of the intake valve to increase the intake negative pressure downstream of the intake throttle valve,
Before execution of the fuel cut, there is provided control means for driving the second variable valve mechanism to retard the opening / closing timing of the exhaust valve and increasing the valve overlap amount with the intake valve. Control device for deceleration of an internal combustion engine.   The control means starts the control to increase the valve overlap amount by the second variable valve mechanism simultaneously with the establishment of the fuel cut execution condition, and then drives the first variable valve mechanism to activate the intake valve. 2. The control device for deceleration of an internal combustion engine according to claim 1, wherein control for increasing the opening degree is started.   The control means performs ignition when the effective opening of the intake valve is increased by the first variable valve mechanism and the valve overlap amount is increased by the second variable valve mechanism before the fuel cut is performed. The internal combustion engine deceleration control device according to claim 1 or 2, wherein the timing is corrected while ensuring misfire suppression.   The said control means cancels | releases the increase control of the valve overlap amount by a 2nd variable valve mechanism after performing the said fuel cut, The any one of Claims 1-3 characterized by the above-mentioned. Control device for deceleration of internal combustion engine.   The said control means cancels | releases the increase control of the valve overlap amount by a 2nd variable valve mechanism immediately after performing the said fuel cut, The any one of Claims 1-4 characterized by the above-mentioned. Control device for deceleration of internal combustion engine.   The control means, after executing the fuel cut, at the time of fuel recovery, the intake valve effective opening increase control by the first variable valve mechanism, the valve overlap amount increase control by the second variable valve mechanism, The control device during deceleration of the internal combustion engine according to any one of claims 1 to 4, wherein the control is canceled.   When the request to increase the intake negative pressure downstream of the intake throttle valve is released, the control means controls the intake valve effective opening increase by the first variable valve mechanism and the second variable valve mechanism. 5. The control device for deceleration of an internal combustion engine according to claim 1, wherein the control for increasing the valve overlap amount is canceled.   The control means performs an effective control for increasing the effective opening of the intake valve by the first variable valve mechanism or an increase control of the valve overlap amount by the second variable valve mechanism after the release. 8. The internal combustion engine deceleration control apparatus according to claim 4, wherein the control is switched to a feedback control to a target value or a current target value.

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