JP5216925B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device applied to an internal combustion engine including a variable valve mechanism that can continuously change the lift characteristics of an intake valve and a negative pressure adjusting valve that adjusts the intake pipe negative pressure.

  In Patent Document 1, in an internal combustion engine provided with a variable valve mechanism that makes the lift amount and operating angle of an intake valve variable and an electronically controlled throttle, the intake air amount of the engine is controlled by the operation of the variable valve mechanism. However, a control device for controlling the intake pipe negative pressure by an electronically controlled throttle is described.

JP 2006-132327 A

  By the way, at the time of starting or idling operation, when the control of the engine intake air amount through the control of the variable valve mechanism and the control of the intake pipe negative pressure through the control of the electronic control throttle are executed in parallel, In any control operation, the intake air amount of the engine changes, and the engine rotation speed changes with the change of the intake air amount. Therefore, the respective control operations interfere with each other and the engine rotation speed becomes unstable. There was a problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device that can stably converge the engine speed with respect to a target value.

Therefore, in the present invention, the means for controlling the intake air amount of the internal combustion engine through the control of the variable valve mechanism capable of continuously changing the lift characteristic of the intake valve is based on the target value and the actual value of the engine speed. The air amount control is performed, and when the air amount control is executed, the gain of the means for controlling the intake pipe negative pressure is reduced through the control of the negative pressure adjusting valve.

  According to the above invention, the intake pipe negative pressure control is prevented from interfering with the control of the lift characteristic for bringing the engine rotation speed close to the target value, and the convergence stability to the target rotation speed by the control of the lift characteristic is reduced. Can be improved.

1 is a system diagram of an internal combustion engine for a vehicle in an embodiment. It is a perspective view which shows the variable lift mechanism of the intake valve in embodiment. It is sectional drawing which shows the principal part of the said variable lift mechanism. It is a figure which shows the variable valve timing mechanism in embodiment. It is a diagram which shows the change characteristic of the center phase of the valve lift amount, valve operating angle, and valve operating angle of the intake valve in the embodiment. It is a flowchart which shows 1st Embodiment of the flow of intake air amount control and negative pressure control. It is a flowchart which shows 2nd Embodiment of the flow of intake air amount control and negative pressure control.

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 shows an internal combustion engine for a vehicle in the embodiment.
An internal combustion engine 101 shown in FIG. 1 is a V-type 6-cylinder engine including two banks 101a and 101b, and an output shaft thereof is connected to a drive wheel of a vehicle via a transmission (not shown).

The combustion chamber 102 of each cylinder of the internal combustion engine 101 communicates with the atmosphere side via an intake duct 103, intake manifolds 104a and 104b, and an intake port 105.
The intake port 102a of the combustion chamber 102 (cylinder) is opened and closed by an intake valve 106. When the intake valve 106 opens when the piston 107 descends, air is sucked into the combustion chamber 102.

  On the other hand, a fuel injection valve 108 is provided for each cylinder in each of the branch portions 140a and 140b of the intake manifolds 104a and 104b, which is an intake passage on the upstream side of the intake valve 106. Is injected into the combustion chamber 102 together with air.

The fuel injection valve 108 is arranged so that the spray is directed to the umbrella portion (intake port 102a) of the intake valve 106.
The fuel injection valve 108 may be an in-cylinder direct injection internal combustion engine that directly injects fuel into the combustion chamber 102. The internal combustion engine 101 is not limited to a V-type engine, but is connected in series or horizontally. It may be a facing type or the like.

  The fuel in the cylinder 102 is ignited and burned by spark ignition by the spark plug 109, and the explosive force generated thereby pushes down the piston 107, and the crankshaft 110 is rotationally driven by the push-down force.

  The exhaust port 102b of the combustion chamber 102 (cylinder) is opened and closed by an exhaust valve 111. When the exhaust valve 111 is opened when the piston 107 is raised, the exhaust gas in the combustion chamber 102 is discharged to the exhaust port 112. Is done.

  An intake camshaft 131 and an exhaust camshaft 132 to which the rotational driving force of the crankshaft 110 is transmitted are provided in each of the banks 101a and 101b, and the intake valve 106 and the exhaust valve 111 are respectively connected to the intake camshaft 131 and the exhaust cam. The shaft 132 is driven to open by rotating.

  Here, the exhaust valve 111 is periodically opened by a cam 132a provided integrally with the exhaust camshaft 132 at a certain maximum valve lift, valve operating angle, and valve timing.

  On the other hand, variable valve timing mechanisms 133a and 133b for continuously varying the rotational phase of the intake camshaft 131 with respect to the crankshaft 110 are provided in the intake camshafts 131 of the banks 101a and 101b, respectively.

  By making the rotational phase of the intake camshaft 131 variable by the variable valve timing mechanisms 133a and 133b, the central phase of the valve operating angle of the intake valve 106 is continuously advanced and retarded.

  Further, between the intake camshaft 131 and a swing cam 4 (described later) that contacts the valve lifter 106a of the intake valve 106 and drives the intake valve 106 to open, the valve operating angle and valve lift amount (maximum) of the intake valve 106 are maximized. Variable lift mechanisms 134a and 134b for continuously changing the valve lift amount are provided for the respective banks 101a and 101b.

  As described above, in the present embodiment, the variable valve timing mechanisms 133a and 133b and the variable lift mechanisms 134a and 134b are provided as variable valve mechanisms that make the lift characteristics of the intake valve 106 variable.

  However, instead of the variable valve timing mechanisms 133a and 133b and the variable lift mechanisms 134a and 134b, an electromagnetically driven valve that opens the intake valve 106 with electromagnetic force can be employed.

  The exhaust ports 112 are connected to the branch portions of the exhaust manifolds 113a and 113b, and the aggregate portions of the exhaust manifolds 113a and 113b are joined together and connected to the exhaust duct 114.

The exhaust duct 114 is provided with a catalytic converter 115 equipped with an exhaust purification catalyst such as a three-way catalyst for purifying the exhaust.
The intake duct 103 is provided with an electronically controlled throttle 116 (negative pressure adjusting valve).

  The electronic control throttle 116 is a mechanism that opens and closes a throttle valve with an actuator such as a motor, and the throttle opening is adjusted by controlling the actuator such as a motor.

  Fuel injection by the fuel injection valve 108, ignition by the spark plug 109, change of the lift characteristic of the intake valve 106 by the variable valve timing mechanisms 133a and 133b and variable lift mechanisms 134a and 134b, and the throttle opening TVO in the electronic control throttle 116 Are controlled by an ECM (Engine Control Module) 121.

  The ECM 121 includes a microcomputer (microprocessor), inputs signals from various sensors, performs arithmetic processing on the input signals according to a program stored in advance, and performs various operation amounts (control signals). And the manipulated variable (control signal) is output.

  Examples of the various sensors include an accelerator opening sensor 122 that detects an accelerator opening degree ACC corresponding to an accelerator pedal depression amount (stroke amount) operated by a vehicle driver, and a cooling water temperature TW (engine temperature) of the internal combustion engine 101. A water temperature sensor 123 for detecting the vehicle speed, a vehicle speed sensor 124 for detecting a traveling speed (vehicle speed) VSP of the vehicle on which the internal combustion engine 101 is mounted, a unit crank angle signal POS and a reference crank angle position each time the crankshaft 110 rotates by a unit angle. A crank angle sensor 125 that outputs a reference crank angle signal REF for each bank, and arranged at a collection portion of the exhaust manifolds 113a and 113b of each bank, respectively, and the air-fuel ratio AF of each bank based on the oxygen concentration in the exhaust gas, respectively. Air-fuel ratio sensors 126a, 126b to be detected at the same time, intake air flow of the internal combustion engine 101 An airflow sensor 127 that detects QA, a throttle opening sensor 128 that detects the opening TVO of the electronic control throttle 116, and a pressure sensor that detects a pressure (intake pipe negative pressure) PB in the intake passage downstream of the electronic control throttle 116 129 and the like are provided.

The ECM 121 controls the fuel injection amount by the fuel injection valve 108 as follows.
First, the cylinder intake air amount is calculated from the detected value by the air flow sensor 127 and the basic fuel injection pulse width TP is calculated based on the cylinder intake air amount.

The calculation of the cylinder intake air amount is performed as disclosed in Japanese Patent Laid-Open No. 2001-50091.
Specifically, the amount of air Ca (Ca = Qa · Δt) flowing into the manifold portion from the amount of intake air (mass flow rate) Qa detected by the airflow sensor 127 is calculated. Here, Δt is a predetermined time, and the amount of air Ca flowing into the manifold portion is calculated every time Δt.

  Further, the cylinder volume Vc is calculated by correcting the cylinder volume at the closing timing IVC of the intake valve 106 based on the cylinder fresh air ratio η according to the overlap amount of the intake / exhaust valves 106 and 111.

The closing timing IVC of the intake valve 106 is determined according to the control amounts of the variable valve timing mechanisms 133a and 133b and the variable lift mechanisms 134a and 134b.
Then, the balance calculation of the air amount Ca flowing into the manifold portion and the cylinder intake air amount Cc flowing out from the manifold portion to the cylinder portion is performed, and the air amount Cm (n) (Cm (n) = Cm (n− 1) While calculating + Ca−Cc (n)), the cylinder intake air amount Cc (Cc = Vc · Cm / Vm) is calculated based on the air amount Vm of the manifold portion and the cylinder volume Vc.

  Further, the basic fuel injection pulse width TP is set so that the actual air / fuel ratio detected from the correction coefficient corresponding to the coolant temperature TW and the outputs of the air / fuel ratio sensors 126a and 126b approaches the target air / fuel ratio. The final fuel injection pulse width TI is calculated by correcting with a fuel ratio feedback correction coefficient or the like.

Then, the injection pulse signal having the fuel injection pulse width TI is individually output to the fuel injection valve 108 of each cylinder in synchronization with the intake stroke of each cylinder.
The fuel injection valve 108 opens for a time corresponding to the fuel injection pulse width TI, and injects an amount of fuel proportional to the valve opening time.

Each ignition plug 109 is directly attached with an ignition module 138 that incorporates an ignition coil and a power transistor that controls energization of the ignition coil.
The ECM 121 calculates the ignition timing based on, for example, the engine load (basic fuel injection pulse width TP) and the engine rotational speed NE, and from the energization time for obtaining the ignition timing and ignition energy to the ignition coil. The energization start timing and the energization cut-off timing are determined, the on / off of the power transistor is controlled by an ignition control signal corresponding to the energization start timing and the energization cut-off timing, and spark ignition at the ignition timing is executed for each cylinder. .

  In the control of the variable valve timing mechanisms 133a and 133b and the variable lift mechanisms 134a and 134b, for example, the target center phase and the target valve lift amount (target valve operating angle) are determined from the target torque (engine load) and the engine speed NE. And the operation amount output to each mechanism is calculated so that the actual center phase / actual valve lift amount (actual valve operating angle) approaches the target.

  In the control of the variable valve timing mechanisms 133a and 133b, for example, the center phase of the valve operating angle of the intake valve 106 is advanced during low load and low rotation, so that the intake valve 106 open period and the exhaust valve 111 open period Are increased, the residual gas amount in the cylinder is increased, and the fuel consumption is reduced.

  Also, in engine operating conditions that require engine output, such as during high loads and high revolutions, the central phase of the valve operating angle of the intake valve 106 is retarded to reduce the overlap, thereby reducing residual gas in the cylinder. Is reduced, the amount of fresh air introduced is relatively increased, and the closing timing IVC of the intake valve 106 is retarded from the bottom dead center BDC (after the bottom dead center). Improves the filling efficiency and improves the output.

  On the other hand, in the control of the variable lift mechanisms 134a and 134b, a target value corresponding to the required air amount of the internal combustion engine 101 is set, and the larger the required intake air amount, the greater the valve lift amount and valve operating angle of the intake valve 106. In other words, the closing timing IVC of the intake valve 106 is controlled to be retarded.

  In other words, in low load and low rotation ranges including idle operation, the valve lift amount and valve operating angle are reduced, and the closing timing IVC is set before the bottom dead center to keep the intake air amount low and increase the load and rotation. Accordingly, the intake air amount is increased by bringing the closing timing IVC closer to the bottom dead center, and at high loads and high rotations, the closing timing IVC is retarded until after the bottom dead center, resulting in higher charging efficiency than the bottom dead center. obtain.

  Thus, by controlling the variable valve timing mechanisms 133a and 133b and the variable lift mechanisms 134a and 134b, the intake air amount (cylinder intake air amount) introduced into the cylinder is controlled. The control function of the variable valve mechanism corresponds to the air amount control means.

  Further, in the control of the electronic control throttle 116, the target opening is set based on the target negative pressure, and the target is set so that the actual intake pipe negative pressure PB detected by the pressure sensor 129 approaches the target negative pressure. The opening is corrected, and the manipulated variable is calculated and output so that the actual opening approaches the target opening. The control function of the electronic control throttle 116 corresponds to negative pressure control means.

  The target negative pressure is set according to the demands of various devices using the intake pipe negative pressure of the internal combustion engine 101. As the device using the intake negative pressure, in this embodiment, the hydraulic brake device 200, and the exhaust gas are used. A recirculation device 250 is provided in the internal combustion engine 101.

  The hydraulic brake device 200 includes a master back 202 (brake booster) as negative pressure boosting means that boosts the operating force of the brake pedal 201 using the intake negative pressure (intake pipe negative pressure) of the internal combustion engine 101; A tandem master cylinder 203 that generates a master cylinder pressure in response to an operation force boosted by the master back 202, and a hydraulic unit 208 that supplies the master cylinder pressure to the wheel cylinders 204 to 207 are configured. .

  An intake pipe negative pressure downstream of the electronic control throttle 116 is introduced into the master back 202 via a negative pressure introduction pipe 209, and in the middle of the negative pressure introduction pipe 209, a negative pressure is introduced. A check valve (one-way valve) 210 is provided for introducing intake negative pressure while preventing leakage of the air.

  The master back 202 is provided with a booster negative pressure sensor 211 that detects a negative pressure (booster negative pressure) BNP in the negative pressure chamber, and an output of the booster negative pressure sensor 211 is output to the ECM 121.

  On the other hand, the exhaust gas recirculation device 250 is interposed in the exhaust gas recirculation passage 251 that connects the exhaust manifold 113b and the intake duct 103 (intake pipe negative pressure generation region) downstream of the electronic control throttle 116, and the exhaust gas recirculation passage 251. The exhaust gas recirculation control valve 252 (electromagnetic valve) is opened by a control signal from the ECM 121.

  When the exhaust gas recirculation control valve 252 is controlled to open while the intake pipe negative pressure is generated, the difference between the pressure in the exhaust manifold 113b and the pressure in the intake duct 103 downstream of the electronic control throttle 116 (intake pipe negative pressure). A part of the exhaust gas is recirculated into the intake duct 103 by the pressure.

  When the exhaust gas is recirculated to the intake system by the exhaust gas recirculation device 250, since the exhaust gas is an inert gas, the maximum combustion temperature is lowered, and the amount of nitrogen oxide NOx discharged from the internal combustion engine 101 can be reduced.

  As described above, the hydraulic brake device 200 requires the intake pipe negative pressure as a boost source for causing the master back 202 to perform the boosting action, and the exhaust gas recirculation device 250 returns the exhaust gas to the intake system. Intake pipe negative pressure is required to generate a pressure difference for this purpose.

  Therefore, the ECM 121 sets a target negative pressure necessary for the boosting action and the exhaust gas recirculation, and the electronic control throttle 116 adjusts so that the actual intake negative pressure detected by the pressure sensor 129 approaches the target negative pressure. Feedback control of the opening.

  The feedback control of the opening degree of the electronic control throttle 116 is performed by calculating an operation amount by, for example, a proportional / integral / differential operation based on a deviation between a target negative pressure and an actual intake negative pressure, and the operation amount is controlled by the electronic control This is executed by outputting to the throttle 116.

  Here, the target negative pressure can be set according to the engine load and the engine speed NE, and the negative pressure in the negative pressure chamber of the master back 202 is insufficient from the output of the booster negative pressure sensor 211. When it is determined that the negative pressure has been set, the target negative pressure can be set to recover the negative pressure.

  By generating the minimum negative pressure necessary for the boosting action and exhaust gas recirculation, the pumping loss due to the intake pipe negative pressure is reduced, and the fuel efficiency performance of the internal combustion engine 101 is improved. .

  In addition, as an apparatus using the intake pipe negative pressure of the internal combustion engine 101 as an operation source, the fuel vapor generated in the fuel tank is once adsorbed by the adsorbent of the canister, and the fuel vapor adsorbed by the adsorbent is used. There is a fuel vapor processing device that is desorbed by the negative pressure of the intake pipe of the internal combustion engine 101 and sucked into the intake duct 103 downstream of the electronic control throttle 116.

FIG. 2 is a perspective view showing the structure of variable lift mechanisms 134a and 134b that continuously vary the valve lift amount (maximum valve lift amount) and valve operating angle of the intake valve 106. FIG.
Above the intake valve 106, an intake camshaft 131 that is rotationally driven by the crankshaft 110 is supported by a cylinder head (not shown) so as to be rotatable along the cylinder row direction.

On the intake camshaft 131, a swing cam 4 that contacts the valve lifter 106a of the intake valve 106 and opens the intake valve 106 is externally fitted so as to be relatively rotatable.
Between the intake camshaft 131 and the swing cam 4, variable lift mechanisms 134a and 134b for continuously changing the valve operating angle and the valve lift amount of the intake valve 106 are provided.

  Further, at one end of the intake camshaft 131, a variable valve timing for continuously changing the center phase of the valve operating angle of the intake valve 106 by changing the rotational phase of the intake camshaft 131 with respect to the crankshaft 110. Mechanisms 133a and 133b are provided.

  As shown in FIGS. 2 and 3, the variable lift mechanisms 134 a and 134 b are fitted on a circular drive cam 11 that is eccentrically fixed to the intake camshaft 131 and fixedly mounted on the drive cam 11. A ring-shaped link 12, a control shaft 13 that extends substantially parallel to the intake camshaft 131 in the cylinder row direction, a circular control cam 14 that is eccentrically fixed to the control shaft 13, and a relative position to the control cam 14 A rocker arm 15 that is rotatably fitted and has one end connected to the tip of the ring-shaped link 12, and a rod-shaped link 16 connected to the other end of the rocker arm 15 and the swing cam 4. Yes.

The control shaft 13 is rotationally driven within a predetermined control range via a gear train (reduction gear) 18 by an actuator such as a motor 17.
With the above configuration, when the intake camshaft 131 rotates in conjunction with the crankshaft 110, the ring-shaped link 12 moves substantially in translation through the drive cam 11, and the rocker arm 15 swings around the axis of the control cam 14. Then, the swing cam 4 swings through the rod-shaped link 16 and the intake valve 106 is driven to open.

  Further, by driving and controlling the motor 17 to change the angle of the control shaft 13, the axial center position of the control cam 14 serving as the rocking center of the rocker arm 15 is changed and the posture of the rocking cam 4 is changed.

  As a result, the valve operating angle and the valve lift amount (maximum valve lift amount) of the intake valve 106 continuously change while the central phase of the valve operating angle of the intake valve 106 remains substantially constant.

Note that the variable lift mechanisms 134a and 134b may be configured such that the center phase of the valve operating angle changes with changes in the valve operating angle and the valve lift amount.
In addition, as an actuator that rotationally drives the control shaft 13, an electric actuator such as a brushless motor or a DC motor, an electromagnetic actuator using electromagnetic force, a hydraulic actuator, or the like can be used.

  FIG. 4 shows the structure of the variable valve timing mechanisms 133a and 133b in which the center phase of the valve operating angle of the intake valve 106 is made variable by continuously changing the rotational phase of the intake camshaft 131 with respect to the crankshaft 110. Indicates.

  The variable valve timing mechanisms 133a and 133b are fixed to the cam sprocket 51 (timing sprocket) rotated by the crankshaft 110 via a timing chain and the end of the intake camshaft 131 and rotate into the cam sprocket 51. A rotating member 53 that is freely housed, a hydraulic circuit 54 that rotates the rotating member 53 relative to the cam sprocket 51, and a relative rotational position between the cam sprocket 51 and the rotating member 53 are selectively selected at predetermined positions. And a locking mechanism 60 for locking.

  The cam sprocket 51 includes a rotating part (not shown) having a tooth part meshed with a timing chain (or timing belt) on the outer periphery, and a housing that is disposed in front of the rotating part and rotatably accommodates the rotating member 53. 56, and a front cover and a rear cover (not shown) for closing the front and rear openings of the housing 56.

  The housing 56 has a cylindrical shape with openings at the front and rear ends, and has a trapezoidal shape in cross section on the inner peripheral surface, and four partition walls 63 provided along the axial direction of the housing 56 are spaced by 90 °. It is projecting at.

  The rotating member 53 is fixed to the front end portion of the intake camshaft 131, and four vanes 78a, 78b, 78c, and 78d are provided on the outer peripheral surface of the annular base 77 at 90 ° intervals.

  Each of the first to fourth vanes 78a to 78d has a substantially inverted trapezoidal cross section, and is disposed in a recess between the partition walls 63. The recesses are separated from each other in the rotational direction, and the vanes 78a to 78d. An advance side hydraulic chamber 82 and a retard side hydraulic chamber 83 are formed between both sides and both side surfaces of each partition wall 63.

The lock mechanism 60 is configured such that the lock pin 84 engages with an engagement hole (not shown) at the initial position of the rotating member 53.
The hydraulic circuit 54 includes two systems, a first hydraulic passage 91 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 82 and a second hydraulic passage 92 that supplies and discharges hydraulic pressure to the retard side hydraulic chamber 83. These hydraulic passages 91 and 92 are connected to a supply passage 93 and drain passages 94a and 94b through passage switching electromagnetic switching valves 95, respectively.

  The supply passage 93 is provided with an engine-driven oil pump 97 that pumps oil in the oil pan 96, while the downstream ends of the drain passages 94 a and 94 b communicate with the oil pan 96.

  The first hydraulic passage 91 is connected to four branch passages 91 d that are formed substantially radially in the base 77 of the rotating member 53 and communicate with the advance-side hydraulic chambers 82. It is connected to four oil holes 92 d that open to the retard side hydraulic chamber 83.

The electromagnetic switching valve 95 is configured such that an internal spool valve body relatively switches and controls the hydraulic passages 91 and 92, the supply passage 93, and the drain passages 94a and 94b.
The ECM 121 controls the energization amount for the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal (operation amount) on which a dither signal is superimposed.

  In the variable valve timing mechanisms 133a and 133b, when a control signal (OFF signal) with a duty ratio (ON time ratio) of 0% is output to the electromagnetic actuator 99, the hydraulic oil pumped from the oil pump 47 is supplied to the second hydraulic passage 92. The hydraulic oil in the advanced hydraulic chamber 82 is supplied to the retarded hydraulic chamber 83 through the first hydraulic passage 91 and discharged from the first drain passage 94a into the oil pan 96. It is.

  Therefore, in the variable valve timing mechanisms 133a and 133b, when a control signal (OFF signal) with a duty ratio of 0% is output to the electromagnetic actuator 99, the internal pressure of the retard side hydraulic chamber 83 is increased while the advance side hydraulic chamber is increased. The internal pressure of 82 is lowered, and the rotating member 53 rotates to the maximum retard angle side via the vanes 78a to 78b. As a result, the opening period of the intake valve 106 (the central phase of the valve operating angle) is relative to the piston position. Relatively changes the delay angle.

  That is, when the energization of the electromagnetic actuator 99 of the variable valve timing mechanisms 133a and 133b is cut off, the central phase of the valve operating angle of the intake valve 106 changes with a delay, and finally the vanes 78a, 78b, 78c and 78d It stops at the most retarded position where it abuts against the partition wall 63.

  In addition, when the variable valve timing mechanism 133a, 133b outputs a control signal (ON signal) with a duty ratio of 100% to the electromagnetic actuator 99, the hydraulic fluid passes through the first hydraulic passage 91 and enters the advance side hydraulic chamber 82. While being supplied, the hydraulic oil in the retard side hydraulic chamber 83 is discharged to the oil pan 96 through the second hydraulic passage 92 and the second drain passage 94b, and the retard side hydraulic chamber 83 becomes low pressure.

  For this reason, when the variable valve timing mechanism 133a, 133b outputs a control signal (ON signal) with a duty ratio of 100%, the rotating member 53 rotates to the maximum advance side via the vanes 78a to 78d, thereby The opening period of the intake valve 106 (the central phase of the valve operating angle) changes relative to the piston position, and finally the vane 78a, 78b, 78c, 78d reaches the partition 63. Stop at the corner position.

  The mechanism for continuously varying the valve operating angle / valve lift amount of the intake valve 106 and the mechanism for continuously varying the central phase of the valve operating angle of the intake valve 106 are shown in FIGS. 4 are not limited to the variable lift mechanisms 134a and 134b and the variable valve timing mechanisms 133a and 133b.

  For example, as a mechanism for continuously changing the center phase of the valve operating angle, a mechanism for rotating the intake camshaft 131 relative to the crankshaft 110 using a gear, in addition to the vane type described above, may be used. In addition to the hydraulic actuator, a mechanism using a motor or an electromagnetic brake as the actuator can be employed.

  As a variable lift mechanism, as disclosed in Japanese Patent Application Laid-Open No. 2008-291742, a mechanism that makes a lift characteristic of an engine valve (suction / exhaust valve) variable by displacing a control shaft in an axial direction by an actuator. Can be adopted.

  A signal of an angle sensor (for example, a potentiometer) 135 that detects the angle of the control shaft 13 is input to the ECM 121, and the actual angle of the control shaft 13 detected by the angle sensor 135 is the valve of the intake valve 106. The amount of operation of the motor 17 of the variable lift mechanisms 134a and 134b is feedback-controlled so as to approach the target angle corresponding to the target value of the operating angle / valve lift amount.

  The ECM 121 measures the valve operating angle by measuring the angle from the reference angle position of the crankshaft 110 detected by the crank angle sensor 125 to the reference angle position of the intake camshaft 131 detected by the intake cam sensor 136. Is detected, and a control signal (operation amount) output to the electromagnetic actuator 99 of the variable valve timing mechanisms 133a and 133b is feedback-controlled so that the center phase approaches the target value.

  The feedback control of the variable lift mechanisms 134a and 134b and the variable valve timing mechanisms 133a and 133b calculates an operation amount by a proportional / integral / differential operation based on a control error, and the operation amount is calculated by each mechanism 134a, 134b, 133a. , 133b and executed.

  As described above, in the variable valve timing mechanisms 133a and 133b, the electromagnetic actuator 99 is turned off to return to the most retarded position which is the initial position (default position). The target is set as an advance amount (advance angle) from the most retarded position.

FIG. 5 shows changes in the lift characteristics of the intake valve 106 due to the variable valve timing mechanisms 133a and 133b and the variable lift mechanisms 134a and 134b.
As shown in FIG. 5, when the variable lift mechanisms 134a and 134b are operated, the valve operation of the intake valve 106 is maintained while the central phase of the valve operation angle of the intake valve 106 remains substantially constant, as indicated by an arrow (A). Both the angle and the valve lift amount (maximum valve lift amount) continuously increase or decrease.

  On the other hand, when the variable valve timing mechanisms 133a and 133b are operated, the valve operating angle and the valve lift amount (maximum valve lift amount) of the intake valve 106 remain constant as shown by the arrows (b). The center phase of the valve operating angle changes.

Here, the control of the intake air amount and intake pipe negative pressure by the ECM 21 will be described with reference to the flowchart of FIG.
The intake air amount / intake pipe negative pressure control routine shown in the flowchart of FIG. 6 is executed every unit time.

First, in step S1001, it is determined whether or not the internal combustion engine 101 is being started.
The time of starting is the time from when cranking is started (starter switch is turned off to on) until the engine speed NE is determined to be stable near the target idle speed (for example, ± 100 rpm) after complete explosion.

  Accordingly, the predicted value of the time may be stored in advance, and the time until the time from the start of cranking reaches the predicted value may be determined as the start state, or the engine speed NE is close to the target idle speed. It is also possible to determine that the engine is in a starting state until it is detected that the motor is stable (for example, ± 100 rpm).

  If the internal combustion engine 101 is being started, the process proceeds to step S1002, and the target value TVEL of the valve lift amount (maximum valve lift amount) of the intake valve 106 is set according to the coolant temperature TW (engine temperature) at the time of start.

Specifically, in order to suppress pre-ignition, the target value TVEL of the valve lift amount is set to a higher value as the cooling water temperature TW (engine temperature) at the start is higher.
That is, at the time of high temperature, the target value TVEL of the valve lift amount (maximum valve lift amount) is increased, thereby delaying the closing timing IVC of the intake valve 106 after bottom dead center and lowering the effective compression ratio. Suppresses the rise in internal air temperature and suppresses pre-ignition.

  On the other hand, when the internal combustion engine 101 is not started, the routine proceeds to step S1003, where the target value TVEL of the valve lift amount of the intake valve 106 is set based on the engine load (target torque) and the engine rotational speed NE.

More specifically, the higher the engine speed NE and the higher the engine load (target torque), the higher the valve lift amount target value TVEL is set.
In step S1004, it is determined whether the internal combustion engine 101 is idling or starting.

If it is during idling or starting, the process proceeds to step S1005.
It is assumed that the start time determined in step S1005 is the same as the start time determined in step S1001.

Further, the idling operation is a time when the accelerator opening ACC is fully closed, and excludes the starting time.
In step S1005, a control error for converging the engine speed NE during idling or starting to the target value NET is calculated.

  That is, the target rotational speed NET is set based on the cooling water temperature TW and whether or not the transmission combined with the internal combustion engine 101 is neutral during idle operation, and the cooling water temperature during start-up. A target rotational speed NET is set based on TW or the like.

Then, a deviation ΔNE (ΔNE = NE−NET) between the actual engine speed NE at that time and the target value NET is calculated as the control error.
Alternatively, a target intake pipe negative pressure PBT corresponding to the target rotational speed NET is set, and a deviation ΔPB (ΔPB = PB−PBT) between the actual intake pipe negative pressure PB and the target intake pipe negative pressure PBT at that time is set. , And calculated as the control error.

  The intake pipe negative pressure PB is expressed as a negative value having a larger absolute value as the atmospheric pressure is 0 mmHg and lower than the atmospheric pressure. That is, the intake pipe negative pressure in the present embodiment is expressed as a relative pressure with respect to the atmospheric pressure.

In step S1006, a correction value HVEL for correcting the target value TVEL of the valve lift amount is set from the control error (deviation ΔNE or deviation ΔPB).
The correction value HVEL can be obtained by referring to a table as shown in the flowchart. If the control error (deviation ΔNE or deviation ΔPB) is negative, a positive value is set as the correction value HVEL. If the control error (deviation ΔNE or deviation ΔPB) is positive, a negative value is set as the correction value HVEL, and the correction value increases as the absolute value of the control error (deviation ΔNE or deviation ΔPB) increases. The absolute value of HVEL is set to be large.

  In other words, when the actual engine speed NE is higher than the target value NET, the target value TVEL of the valve lift amount is corrected to be lower (the closing timing IVC of the intake valve 106 is advanced before the bottom dead center). The intake air amount is reduced by reducing the valve lift amount, and the actual engine rotational speed NE is lowered so as to approach the target value NET.

  When the actual engine speed NE is lower than the target value NET, the valve lift amount target value TVEL is corrected to be higher (the closing timing IVC of the intake valve 106 is brought close to the bottom dead center), and the valve lift is increased. As the amount increases, the amount of intake air increases and the actual engine speed NE increases to approach the target value NET.

  On the other hand, when the intake pipe negative pressure PB is closer to the atmospheric pressure than the target value PBT, it is determined that the intake air amount is larger than the target. Therefore, the target value TVEL of the valve lift amount is corrected to be lower. By reducing the lift amount, the intake air amount is reduced, and the actual engine speed NE is lowered so as to approach the target value NET.

  Further, when the intake pipe negative pressure PB is on the negative pressure side with respect to the target value PBT, it is determined that the intake air amount is smaller than the target. Therefore, the target value TVEL of the valve lift amount is corrected to be higher, and the valve As the lift amount increases, the intake air amount increases, and the actual engine rotational speed NE increases to approach the target value NET.

  In step S1007, the target value TVEL of the valve lift amount of the intake valve 106 set in step S1002 or step S1003 is corrected with the correction value HVEL set in step S1006, and the correction result is set as the final target value TVEL. To do.

  If the variable lift mechanisms 134a and 134b are corrected based on the target value TVEL corrected and set in step S1007, the valve lift amount of the intake valve 106 is actually measured based on the target value set in step S1002 or step S1003. The engine speed NE is corrected so as to approach the target value NET, and the stability of the engine 101 during idling or starting can be improved.

  In step S1008, it is determined in step S1004 that the engine is in a starting state, and the processing in steps S1005 to 1007 is performed, and at this time, it is determined whether or not the accelerator is in an acceleration state.

  In the determination of the acceleration state, when the increase amount ΔACC of the accelerator opening ACC per unit time is equal to or greater than a threshold value and the accelerator opening ACC is increasing and changing at a predetermined speed or more, the acceleration state is to decide.

  As for the threshold value to be compared with the change amount ΔACC and the predetermined speed, the fluctuation of the intake air amount by the control of the electronic control throttle 116 for bringing the intake pipe negative pressure PB close to the target negative pressure is used for the control of the variable lift mechanisms 134a and 134b. As a value when it becomes small enough not to interfere, it is previously adapted based on experiments and simulations.

  If it is during idling or when starting, but the accelerator is not opened, the process proceeds to step S1009 (negative pressure control limiting means), and the opening degree of the electronic control throttle 116 (negative pressure adjusting valve). The control action of intake pipe negative pressure through control is limited.

  That is, the opening degree (throttle opening degree) of the electronic control throttle 116 is operated based on the deviation (control error) between the actual intake pipe negative pressure PB detected by the pressure sensor 129 and the target negative pressure. In step S1009, the feedback operation, in other words, the opening degree change for reducing the deviation (control error) is suppressed to a small extent.

  Specifically, the feedback operation for obtaining the target intake pipe negative pressure by fixing the opening degree of the electronic control throttle 116 (throttle opening degree) to the opening degree at which the intake air amount required for idle operation is obtained. Or the gain of the feedback operation (the control gain of the throttle opening operation amount with respect to the control error) is controlled by the control of the electronic control throttle 116 (intake pipe pressure PB) in step S1011 (negative pressure control means) described later. This is lower than when the control is performed.

  As described above, the opening when the opening of the electronically controlled throttle 116 (throttle opening) is fixed is the opening corresponding to the intake air amount required for idle operation, but the engine has a large engine friction. Since the amount of intake air required for idle operation increases at a low temperature of 101, it is preferable to determine the fixed opening according to the coolant temperature that represents the engine temperature.

  As described above, in steps S1005 to S1007, the valve lift amount of the intake valve 106 is feedback controlled so that the actual engine speed NE approaches the target value NET. When the feedback control of the electronic control throttle 116 (feedback control of the intake pipe pressure PB) is performed to bring the actual intake pipe negative pressure PB closer to the actual intake pipe pressure PB, the mutual control interferes and the convergence stability in each control is impaired. As a result, hunting occurs or convergence responsiveness to the target decreases.

  Therefore, the control operation of the intake pipe negative pressure through the opening control of the electronic control throttle 116 (negative pressure adjusting valve) is limited, and the fluctuation of the intake air amount generated by the control of the intake pipe negative pressure is sufficiently reduced. Thus, by controlling the valve lift amount so that the actual engine rotational speed NE approaches the target value NET, control interference is suppressed, and by controlling the valve lift amount of the intake valve 106, the actual engine rotational speed NE is controlled. Can be converged with good response and stability near the target value NET.

  For example, when the load of an auxiliary machine driven by the engine 101 is applied and the engine rotational speed NE is decreased, when the intake air amount is being increased by controlling the valve lift amount, the actual intake pipe negative pressure PB is If the control is performed to increase the opening of the electronic control throttle 116 (negative pressure adjusting valve) because it is larger than the target negative pressure, the intake air amount will increase excessively.

  In addition, since the load of the auxiliary machine driven by the engine 101 is applied and the engine rotational speed NE is reduced, when the intake air amount is being increased by controlling the valve lift amount, the actual intake pipe negative pressure PB is If control is performed to reduce the opening degree of the electronic control throttle 116 (negative pressure adjusting valve) because it is lower than the target negative pressure, an increase in intake air amount required from the rotational speed control cannot be obtained.

  On the other hand, as described above, the opening degree of the electronically controlled throttle 116 (negative pressure adjusting valve) is fixed to an opening degree corresponding to the intake air amount required for idle operation, or the throttle opening manipulated variable is controlled. If restrictions such as lowering the gain are added, the intake air amount can be changed toward the target in a responsive and accurate manner by controlling the valve lift amount, and the engine rotation speed toward the target is responsive and stable. It can be converged.

  It should be noted that the opening degree of the electronic control throttle 116 (negative pressure adjusting valve) is fixed to an opening degree corresponding to the intake air amount required for idle operation, or the control gain of the throttle opening manipulated variable is reduced. However, the followability of the actual intake pipe negative pressure PB with respect to the target negative pressure is reduced, but high accuracy is not required for the negative pressure as the operation source of the hydraulic brake device 200 or the exhaust gas recirculation device 250. The effect on performance and exhaust gas recirculation control is sufficiently small.

  On the other hand, in idling speed control, if the intake air amount does not change with good response, the engine speed fluctuates greatly and engine stall is likely to occur, and the target idling engine speed is set higher to avoid engine stall. Need to do.

  Therefore, the idling speed control is prioritized over the negative pressure control, and the idling speed is stabilized and the engine stall resistance is improved while ensuring the necessary and sufficient value as the intake pipe negative pressure PB. If the rotation is stabilized, the target idle rotation speed can be reduced, and thereby the fuel efficiency and quietness during idling can be improved.

  However, when a negative pressure is required such as when the negative pressure (booster negative pressure) BNP in the negative pressure chamber of the master back 202 of the hydraulic brake device 200 is small (close to atmospheric pressure) and the boost function cannot be performed, the intake pipe negative pressure is required. It is possible to cancel the restriction on the control operation and to bring the actual intake pipe negative pressure PB close to the target negative pressure quickly.

  Here, the gain of the control of the electronic control throttle 116 to bring the actual intake pipe negative pressure PB close to the target negative pressure includes the reduction of the proportional constant / integral constant in the proportional / integral operation, This includes limiting the amount of change in the operation amount to a limit value or less, filtering processing such as weighted averaging of the operation amount, and correcting the control error to be smaller than actual.

In other words, the process may be any process that reduces the change in the operation amount output for the same control error as compared with the control in step S1011.
If it is determined in step S1004 that the engine is not idling or starting, that is, if the internal combustion engine 101 is not in an idling operation and is not in starting, the process proceeds to step S1010 and the target set in step S1003 is reached. The value TVEL is set as it is to the final target value TVEL, and the variable lift mechanisms 134a and 134b are controlled.

In the next step S1011, control of the electronic control throttle 116 for causing the actual intake pipe negative pressure PB to approach the target negative pressure is executed.
The control of the electronic control throttle 116 in step S1011 is not limited as in step S1009, and the intake pipe negative pressure PB changes toward the target value with a higher gain than the control in step S1009 with good response. Let

  When the routine proceeds to step S1011, feedback control of the valve lift amount of the intake valve 106 for bringing the actual engine speed NE close to the target value NET is not performed, so the actual intake pipe negative pressure PB is set to the target value. The control of the electronic control throttle 116 for approaching does not interfere with the feedback control of the valve lift amount.

  Accordingly, in step S1011, the control of the electronic control throttle 116 for bringing the intake pipe negative pressure PB close to the target value is not limited, and the intake pipe negative pressure PB is brought closer to the target value with a higher response than in step S1009. To do.

  Also, if it is determined in step S1008 that the engine is at the time of start-up and acceleration is increasing, the process proceeds to step S1011 and the electronic for making the intake pipe negative pressure PB close to the target value. The control of the control throttle 116 is not limited, and the intake pipe negative pressure PB is brought close to the target value with a high response.

  That is, during acceleration, the target negative pressure changes, and it is required to change the actual intake pipe negative pressure in response to the change, while the electronic control throttle 116 for bringing the intake pipe negative pressure PB closer to the target value. Even if the above control is performed, the control does not interfere with the control of the valve lift amount of the intake valve 106, and therefore, the process proceeds to step S1011 as in the case where it is determined in step S1004 that the engine is not idling and is not started.

  If the electronic control throttle 116 is controlled in step S1009 or step S1011, the process proceeds to step S1012 (air amount control means), and the variable lift mechanisms 134a and 134b are controlled based on the final target value TVEL.

The variable lift mechanisms 134a and 134b have a large amount of friction when the engine 101 is started and are difficult to operate with good response.
Therefore, in step S1005 to step S1007, the correction of the target value TVEL for bringing the engine speed close to the target is performed during the idling operation, and at the start, the target PBT of the intake pipe negative pressure is set to the actual engine speed NE. An embodiment that can be configured to be corrected according to the deviation from the target value NET will be described with reference to the flowchart of FIG.

  In the flowchart of FIG. 7, the processes in steps S2001 to S2009 are the same as those in steps S1001 to S1009 and S1012 in the flowchart of FIG. 6, but when it is determined in step S2004 that the engine is in the idle operation state. The difference is that the process proceeds to step S2005 and thereafter.

  That is, in the flowchart of FIG. 7, during idle operation, negative pressure control such as fixing the electronic control throttle 116 is executed, while feedback of the valve lift amount to bring the actual rotational speed closer to the target idle rotational speed. Control is executed to converge to the target idle speed.

  On the other hand, if it is determined in step S2004 that the engine is not idling, the process proceeds to step S2010, and the target value PBT of the intake pipe negative pressure is set according to the engine load and engine speed at that time.

Next, in step S2011, it is determined whether or not it is a start time in the same manner as in step S1004.
If it is a start time, the process proceeds to step S2012, where it is determined whether or not it is an acceleration request. If there is no acceleration request and the accelerator is fully closed, the process proceeds to step S2013.

  In step S2013, a correction value is set based on the deviation ΔNE in the same manner as in step S2006. However, the correction value in step S2013 is a correction value HPB for correcting the target value PBT.

  The correction value HPB can be obtained by referring to a table as shown in the flowchart. If the deviation ΔNE is negative, a positive value is set as the correction value HPB, and the deviation ΔNE is positive. If there is, a negative value is set as the correction value HPB, and the absolute value of the correction value HPB is set to increase as the absolute value of the deviation ΔNE increases.

  That is, when the actual engine speed is higher than the target, the target value PBT is set to a lower pressure, so that the opening degree of the electronic control throttle 116 is further reduced, the intake air amount is reduced, and the engine speed is reduced. Reduce speed to get closer to the target.

In step S2014, the target value PBT set in step S2010 is corrected and set using the correction value HPB.
In the next step S2015, the variable lift mechanisms 134a and 134b are controlled in accordance with the target lift amount set in step S2002.

  Further, in the next step S2016, the opening degree of the electronic control throttle 116 is feedback controlled based on the difference between the target value PBT corrected in step S2014 and the actual intake pipe negative pressure.

  On the other hand, if it is determined in step S2011 that it is not a start time, that is, if the vehicle is not idling and is not started, the vehicle is driven by the internal combustion engine 101, and an acceleration request is determined in step S2012. The process proceeds to step S2017 and step S2018, and the variable lift mechanisms 134a and 134b are controlled based on the target lift amount set in step S2003, and the opening degree of the electronic control throttle 116 is set in the intake pipe set in step S2010. Feedback control is performed so as to obtain a target value PBT of negative pressure.

  As described above, in the embodiment shown in the flowchart of FIG. 7, at the time of starting, the valve lift amount is controlled to the target value at the time of starting, and the lift amount is not corrected by the rotation speed error, but according to the rotation speed error. By correcting the target value PBT, the opening degree of the electronic control throttle 116 is corrected so as to approach the target rotational speed at the start.

Since the opening degree of the electronically controlled throttle 116 can be changed with a high response even at the time of starting, the rotational stability at the time of starting can be improved.
If the actual engine speed NE cannot be brought close to the target speed with the throttle opening being fixed in step S1009 or step S2008 (the actual engine speed NE does not change or changes toward the target speed). However, when it takes time to converge to the target speed), it is preferable to release the throttle opening.

  Further, when the actual engine speed NE is largely overshooted with respect to the target by performing control to bring the actual engine speed NE close to the target speed with the throttle opening being fixed in step S1009 or step S2008. In addition, the fixed opening degree can be lowered to suppress the occurrence of overshoot.

  Further, when releasing the state where the opening degree of the electronic control throttle 116 is fixed and starting the control for obtaining the target intake pipe negative pressure, the change (change of the opening degree of the electronic control throttle 116 is changed. It is preferable to limit the (speed) to a small value to suppress the occurrence of torque fluctuation and rotation fluctuation.

Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) a control device applied to an internal combustion engine including a variable valve mechanism that can continuously change the lift characteristics of the intake valve and a negative pressure adjusting valve that adjusts the intake pipe negative pressure;
Negative pressure control means for controlling intake pipe negative pressure through control of the negative pressure regulating valve;
An air amount control means for controlling an intake air amount of the internal combustion engine through control of the variable valve mechanism;
During idling operation of the internal combustion engine, an idling rotation control means for fixing the opening of the negative pressure adjusting valve and controlling the variable valve mechanism to bring the engine rotation speed close to a target value;
At the time of starting the internal combustion engine, the lift characteristic of the intake valve is fixed, and the start time rotation control means for controlling the negative pressure adjusting valve to bring the engine speed close to the target value;
A control device for an internal combustion engine, including:

According to the above invention, during idle operation, the opening of the negative pressure adjusting valve is fixed and the variable valve mechanism is controlled to bring the engine speed close to the target value. It is possible to suppress idle rotation from becoming unstable, and at the time of start-up, the lift characteristic of the intake valve is fixed and the negative pressure adjustment valve is controlled to bring the engine speed close to the target value. Even when the valve mechanism cannot be operated with good response, the engine rotation at the start can be controlled toward the target with good response .

(B) In the control device for an internal combustion engine according to any one of claims 1 to 3 ,
The air amount control for making the engine rotation speed close to the target value in the air amount control means is the difference between the actual engine rotation speed and the target rotation speed, or the actual intake pipe negative pressure and the target intake pipe negative pressure. A control apparatus for an internal combustion engine, which is control for correcting a target value of a lift characteristic of the intake valve based on a deviation.

  According to the above invention, the engine rotational speed is brought close to the target by correcting the target value of the lift characteristic of the intake valve based on the engine rotational speed error or the intake pipe negative pressure error.

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 102 ... Combustion chamber, 103 ... Intake duct, 104a, 104b ... Intake manifold, 105 ... Intake port, 106 ... Intake valve, 108 ... Fuel injection valve, 110 ... Crankshaft, 111 ... Exhaust valve, 116 ... Electronic throttle 121, ECM (engine control module), 122 ... Accelerator opening sensor, 123 ... Water temperature sensor, 124 ... Vehicle speed sensor, 125 ... Crank angle sensor, 127 ... Air flow sensor, 128 ... Throttle opening sensor, 129: Pressure sensor, 133a, 133b: Variable valve timing mechanism (variable valve mechanism), 134a, 134b: Variable lift mechanism (variable valve mechanism), 200: Hydraulic brake device, 202: Master back (negative pressure booster) ), 250 ... exhaust gas recirculation device

Claims (3)

A control device applied to an internal combustion engine including a variable valve mechanism that can continuously change the lift characteristics of an intake valve and a negative pressure adjustment valve that adjusts an intake pipe negative pressure,
Negative pressure control means for controlling intake pipe negative pressure through control of the negative pressure regulating valve;
Means for controlling the amount of intake air of the internal combustion engine through control of the variable valve mechanism, and means for controlling the amount of air to bring the engine speed close to a target value;
A negative pressure control limiting means for reducing the gain of the negative pressure control means when the air quantity control means performs air quantity control for bringing the engine speed close to a target value;
A control device for an internal combustion engine, including: 2. The control device for an internal combustion engine according to claim 1, wherein the air amount control means performs air amount control for bringing the engine rotation speed close to a target value at least one of idle operation and start-up of the internal combustion engine. 3. The control device for an internal combustion engine according to claim 1, further comprising an acceleration prohibiting unit that prohibits a decrease in gain of the negative pressure control unit by the negative pressure control limiting unit when acceleration is required .