JP5249814B2 - Control device for variable valve mechanism - Google Patents

Description

  The present invention relates to a control device for a variable valve mechanism that controls a variable valve mechanism that varies a valve timing of an intake valve of an engine in accordance with an operating state of the engine.

  Patent Document 1 describes that the intake air amount of the engine is controlled by variably controlling the operation characteristic (valve timing / lift amount) of the intake valve, and the operation characteristic of the intake valve is controlled in this way. In a system that adjusts the intake air amount by doing so, it is known that the intake pipe pressure is controlled by a throttle valve.

JP 2006-105101 A

  By the way, the change in the cylinder filling efficiency during acceleration is influenced by the closing timing of the intake valve and the intake pipe pressure. There has been a problem that the torque response during acceleration may be reduced by changing in the direction of reduction.

  The present invention has been made in view of the above problems, and provides a control device for a variable valve mechanism capable of realizing a high torque response even when the closing timing of the intake valve changes in the direction of lowering the cylinder charging efficiency during acceleration. The purpose is to provide.

Therefore, in the control apparatus for the variable valve mechanism according to the present invention, the change of the valve timing is stopped or the engine operating state is stopped until the intake pipe pressure from the start of acceleration of the engine reaches a predetermined pressure. The change of the valve timing with respect to the change was delayed.
In the control device for a variable valve mechanism according to the present invention, the advancement of the intake valve before the bottom dead center occurs until the intake pipe pressure reaches a predetermined pressure from the start of acceleration of the engine. Stops the angle or delays the advance angle change before the bottom dead center of the closing timing of the intake valve with respect to the change of the engine operating state, and responds to changes in the engine operating state except for the advance angle before the bottom dead center The closing time is changed.

  According to the above invention, if the change of the valve timing (closing timing) accompanying acceleration is delayed, the intake pipe pressure increases during that time, and even if the valve timing (closing timing) moves in the direction of decreasing the cylinder charging efficiency, The torque response during acceleration can be improved by changing the valve timing under a relatively high intake pipe pressure.

1 is a system diagram of a vehicle engine in an embodiment. It is a perspective view which shows the lift and operating angle variable mechanism of the intake valve in embodiment. It is sectional drawing which shows the principal part of the said lift and working angle variable mechanism. It is a figure which shows the center phase variable mechanism in embodiment. It is a diagram which shows the change characteristic of the lift / valve operating angle / center phase of the valve operating angle of the intake valve in the embodiment. It is a control block diagram of an electronically controlled throttle, a lift / operating angle variable mechanism, and a center phase variable mechanism in the embodiment. It is a flowchart which shows control of the electronic control throttle 104 at the time of acceleration in embodiment, a lift and a working angle variable mechanism, and a center phase variable mechanism. It is a block diagram which shows the acceleration determination process based on the accelerator opening APO in embodiment. FIG. 6 is a diagram showing a correlation between intake valve closing timing IVC and intake pipe pressure and cylinder charging efficiency ηv in the embodiment. In the embodiment, a time chart showing changes in the center phase, the closing timing, the intake pipe pressure, and the cylinder charging efficiency ηv when the smoothing process is performed on the target of the center phase and when the smoothing process is not performed. is there. In the embodiment, it is a diagram showing the correlation between the threshold value PBSL of the intake pipe pressure PB used for determining the end of the delay process and the engine speed NE. 6 is a time chart showing changes in the center phase, closing timing, intake pipe pressure, and cylinder charging efficiency ηv when the delay process is performed on the target of the center phase and when the delay process is not performed in the embodiment.

Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of a vehicle engine in the embodiment.
In FIG. 1, an electronic control throttle 104 that drives a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of an engine (internal combustion engine) 101, and combustion is performed via the electronic control throttle 104 and the intake valve 105. Air is sucked into the chamber 106.

  Further, a fuel injection valve 131 is provided in the intake port 130 upstream of the intake valve 105 of each cylinder, and the fuel injection valve 131 is an amount proportional to the injection pulse width of the injection pulse signal sent from the engine control unit 114. Inject fuel.

The fuel sucked into the combustion chamber 106 together with air is ignited and burned by spark ignition by a spark plug (not shown).
An in-cylinder direct injection type engine that directly injects fuel into the combustion chamber may be used.

  The combustion gas in the combustion chamber 106 is exhausted from the combustion chamber 106 through the exhaust valve 107, purified by the front catalytic converter 108 and the rear catalytic converter 109, and then released into the atmosphere.

  The exhaust valve 107 is driven to open by a cam 111 pivotally supported on the exhaust camshaft 110, and is driven to open while maintaining a certain valve lift amount, valve operating angle, and valve timing according to the shape of the cam 111. .

  On the other hand, the intake valve 105 is driven to open by the rotation of the intake camshaft 3, but the valve lift amount, valve operating angle, and valve timing (opening characteristic) can be changed by a variable valve mechanism.

  As the variable valve mechanism, a center phase variable mechanism that continuously varies the center phase of the valve operating angle of the intake valve 105 by continuously varying the rotational phase of the intake camshaft 3 with respect to the crankshaft 120. 113 (variable valve operating mechanism) and a lift / operating angle variable mechanism 112 that continuously varies the valve lift amount and the valve operating angle of the intake valve 105 are provided.

The valve lift amount changed by the lift / operating angle variable mechanism 112 is the maximum valve lift amount during the opening period of the intake valve.
The engine control unit 114 incorporating the microcomputer sets the fuel injection amount, the ignition timing, the target torque, the target intake pipe pressure, and the like by arithmetic processing according to a program stored in advance, and based on these, the fuel injection valve 131, the operation amount (control signal) of the power transistor for the ignition coil, the electronic control throttle 104, the lift / operation angle variable mechanism 112 and the center phase variable mechanism 113 is calculated and output.

  The engine control unit 114 includes an air flow sensor 115 for detecting the intake air flow rate QA of the engine 101, an accelerator pedal sensor 116 for detecting an accelerator pedal depression amount (accelerator opening) APO operated by a vehicle driver, and a crankshaft. A crank angle sensor 117 that outputs a crank angle signal CAS at every 120 reference angle positions, 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 TW of the engine 101, and an intake camshaft Detection signals from an intake cam sensor 132 that outputs a cam signal CAMIN at every three reference angle positions, an intake pipe pressure sensor 133 that detects an intake pipe pressure (boost) PB, and the like are input.

FIG. 2 is a perspective view showing the structure of the lift / operating angle variable mechanism 112 that continuously varies the valve lift amount and valve operating angle of the intake valve 105.
Above the intake valve 105, an intake camshaft 3 that is rotationally driven by the crankshaft 120 is supported by a cylinder head (not shown) so as to be rotatable along the cylinder row direction.

A swing cam 4 that contacts the valve lifter 105a of the intake valve 105 and opens the intake valve 105 is fitted on the intake camshaft 3 so as to be relatively rotatable.
Between the intake camshaft 3 and the swing cam 4, there is provided a variable lift / operating angle mechanism 112 for continuously changing the valve operating angle and valve lift amount of the intake valve 105.

  Further, at one end of the intake camshaft 3, a center phase variable for continuously changing the center phase of the valve operating angle of the intake valve 105 by changing the rotational phase of the intake camshaft 3 with respect to the crankshaft 120. A mechanism 113 is provided.

  As shown in FIGS. 2 and 3, the lift / operating angle variable mechanism 112 includes a circular drive cam 11 that is eccentrically fixed to the intake camshaft 3, and is externally fitted to the drive cam 11 so as to be relatively rotatable. A ring-shaped link 12 that extends, a control shaft 13 that extends substantially parallel to the intake camshaft 3 in the cylinder row direction, a circular control cam 14 that is fixed to the control shaft 13 in an eccentric manner, and the control cam 14 A rocker arm 15 that is fitted so as to be relatively rotatable 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. ing.

The control shaft 13 is rotationally driven within a predetermined control range via a gear train 18 by an actuator such as a motor 17.
With the above configuration, when the intake camshaft 3 rotates in conjunction with the crankshaft 120, 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 105 is driven to open.

  Further, by driving and controlling the motor 17 to change the rotation 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 changes and the posture of the rocking cam 4 changes. .

As a result, the valve operating angle and the valve lift amount of the intake valve 105 continuously change while the central phase of the valve operating angle of the intake valve 105 remains substantially constant.
The variable lift / operating angle mechanism 112 may be configured so that the central phase of the valve operating angle changes simultaneously with the continuous change of the valve operating angle and the valve lift amount.

In addition, a hydraulic actuator can be used in place of the motor 17 as an actuator for rotationally driving the control shaft 13.
FIG. 4 shows the structure of the center phase variable mechanism 113 that makes the center phase of the valve operating angle of the intake valve 105 variable.

  The center phase variable mechanism 113 is fixed to the cam sprocket 51 (timing sprocket) that is rotationally driven by the crankshaft 120 via a timing chain, and is fixed to the end of the intake camshaft 3 so as to be rotatable in the cam sprocket 51. The rotary member 53 accommodated, the hydraulic circuit 54 for rotating the rotary member 53 relative to the cam sprocket 51, and the relative rotational position of the cam sprocket 51 and the rotary member 53 are selectively locked at predetermined positions. And a lock mechanism 60.

  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 3, and four vanes 78 a, 78 b, 78 c, 78 d 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 engine control unit 114 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 center phase variable mechanism 113, 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 passes through the second hydraulic passage 92. The hydraulic oil in the advance side hydraulic chamber 82 is discharged to the oil pan 96 from the first drain passage 94a through the first hydraulic passage 91. is there.

  Therefore, in the center phase variable mechanism 113, 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 increases while the advance side hydraulic chamber 82 The internal pressure decreases, 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 105 (the central phase of the valve operating angle) is relative to the piston position. The angle changes slowly.

  That is, when the energization of the electromagnetic actuator 99 of the center phase variable mechanism 113 is cut off, the center phase of the valve operating angle of the intake valve 105 changes with a delay, and finally stops at the most retarded position.

  When the center phase variable mechanism 113 outputs a control signal (ON signal) with a duty ratio of 100% to the electromagnetic actuator 99, the hydraulic oil is supplied into the advance side hydraulic chamber 82 through the first hydraulic passage 91. At the same time, 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.

  Therefore, when the center phase variable mechanism 113 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. The opening period of the valve 105 (the center phase of the valve operating angle) changes relative to the piston position.

  Note that a lift / operation angle variable mechanism 112 that continuously varies the operating angle / lift amount of the intake valve 105, and a center phase variable mechanism 113 that continuously varies the center phase of the valve operating angle of the intake valve 105. Is not limited to the structure shown in FIGS.

  For example, as a center phase variable mechanism for continuously changing the center phase of the valve operating angle, a mechanism for rotating the intake camshaft 3 relative to the crankshaft 120 using a gear in addition to the vane type described above. In addition to a hydraulic actuator, a mechanism using a motor or an electromagnetic brake as an actuator can be employed.

  The engine control unit 114 calculates the target angle of the control shaft 13 corresponding to the target values of the valve operating angle and valve lift amount of the intake valve 105 based on the operating state of the engine 101, and is detected by the angle sensor 134. The operation amount of the motor 17 is feedback-controlled so that the actual angle (control amount) of the control shaft 13 approaches the target angle.

  Further, the engine control unit 114 calculates a target value (target advance amount) of the center phase of the valve operating angle based on the operating state of the engine 101, and the actual center phase (control amount) becomes the target value. A control signal (operation amount) output to the electromagnetic actuator 99 of the center phase variable mechanism 113 is feedback-controlled so as to approach.

  The actual center phase is detected by measuring the angle from the reference angle position of the crankshaft 120 detected by the crank angle sensor 117 to the reference angle position of the intake camshaft 3 detected by the intake cam sensor 132. .

  As described above, in the center phase variable mechanism 113, the electromagnetic actuator 99 is turned off to return to the most retarded position that is the initial position (default position). The advance amount from the most retarded position (advance angle) is set.

FIG. 5 shows changes in the opening characteristics of the intake valve 105 by the center phase variable mechanism 113 and the lift / operating angle variable mechanism 112.
As shown in FIG. 5, when the lift / operating angle variable mechanism 112 is operated, the center phase of the valve operating angle of the intake valve 105 remains substantially constant as indicated by the arrow (A), and the valve of the intake valve 105 is maintained. Both the operating angle and the valve lift amount continuously increase or decrease.

  On the other hand, when the center phase variable mechanism 113 is operated, the center phase of the valve operating angle of the intake valve 105 changes while the valve operating angle and valve lift amount of the intake valve 105 remain constant, as shown by arrows (b). To do.

Hereinafter, control of the electronic control throttle 104, the center phase variable mechanism 113, and the lift / operating angle variable mechanism 112 by the engine control unit 114 will be described in detail.
FIG. 6 is a block diagram showing control functions of the electronic control throttle 104, the center phase variable mechanism 113, and the lift / operating angle variable mechanism 112 by the engine control unit 114.

In the following description and drawings, the center phase variable mechanism 113 may be abbreviated as VTC, and the lift / operating angle variable mechanism 112 may be abbreviated as VEL.
In FIG. 6, the detection result of the engine operating state such as the engine speed NE, the intake pipe pressure PB, the accelerator opening APO, and the engine load (intake air amount) is input to the target torque calculation unit 201.

The engine speed NE is calculated, for example, by measuring the cycle of the crank angle signal CAS.
The target torque calculation unit 201 calculates the target torque Ttg from the engine speed NE, the accelerator opening APO, and the like, and outputs the target torque Ttg together with the engine speed NE and the like.

The target valve timing calculation unit 202 calculates control targets for the center phase variable mechanism 113 and the lift / operating angle variable mechanism 112, respectively.
The target valve timing calculation unit 202 stores a map storing the control target (target advance value) of the center phase variable mechanism 113 according to the target torque Ttg and the engine speed NE, the target torque Ttg, and the engine speed NE. And a map storing a control target (target lift / operation angle: target angle of the control shaft 13) of the variable lift / operation angle mechanism 112 in advance.

  Then, the target values corresponding to the target torque Ttg and the engine speed NE at that time are respectively retrieved from the map, and based on these targets, the center phase variable mechanism 113 and the lift / actuation are operated. By controlling the angle variable mechanism 112, the cylinder intake air amount corresponding to the target torque Ttg is controlled.

Further, the target boost calculation unit 203 calculates a target intake pipe pressure TPB based on the target torque Ttg, the engine speed NE, and the like.
The target intake pipe pressure (target boost) TPB is based on a request to supply a negative pressure as a boost source to a brake booster provided in a vehicle during low load operation including an idle operation state and a deceleration operation state. The electronic control throttle 104 is feedback-controlled based on the deviation between the actual intake pipe pressure PB detected by the intake pipe pressure sensor 133 and the target intake pipe pressure TPB, so that the actual intake pipe pressure PB Is adjusted to the target intake pipe pressure TPB.

  In the IVC calculation unit 204, from the control target (target advance angle value) of the center phase variable mechanism 113 and the control target of the lift / operation angle variable mechanism 112 (target lift / operation angle: target angle of the control shaft 13), The closing timing IVC of the intake valve 105 is calculated when the center phase variable mechanism 113 and the lift / operating angle variable mechanism 112 are controlled to the respective targets.

  Since the central phase of the valve operating angle of the intake valve 105 becomes the most retarded angle by stopping the energization of the electromagnetic actuator 99 of the central phase variable mechanism 113, the control target of the central phase variable mechanism 113 is the maximum value. It is set as the advance amount from the retard position.

  Further, in the variable lift / operating angle mechanism 112, the valve lift amount and the valve operating angle are determined by the angle of the control shaft 13, so that the target angle of the control shaft 13 is set as the control target of the variable lift / operating angle mechanism 112. Alternatively, the target valve lift amount or the target valve operating angle may be set.

  As described above, the target advance value that is the control target of the center phase variable mechanism 113 is the advance amount from the most retarded position that is known, and therefore, the valve operating angle is determined from the target advance value at that time. The center phase, in other words, the crank angle corresponding to the center position of the opening period of the intake valve 105 is obtained.

  On the other hand, since the valve operating angle is the crank angle during the opening period of the intake valve 105, the crank angle that is half the valve operating angle from the center position during the opening period of the intake valve 105 is the opening timing IVO of the intake valve 105. Thus, the crank angle after the half of the valve operating angle from the center position of the opening period of the intake valve 105 becomes the closing timing IVC of the intake valve 105.

  Here, when the control target of the lift / operating angle variable mechanism 112 is set as the target angle of the control shaft 13, the valve operating angle is determined by the angle of the control shaft 13 as described above. By converting the target angle into the target valve operating angle, the crank angle corresponding to the closing timing IVC can be obtained.

  When the control target of the variable lift / operating angle mechanism 112 is set as the target valve lift amount, the target valve lift amount is converted into the target valve operating angle, and the crank angle corresponding to the closing timing IVC is obtained. be able to.

  Further, the target torque correction unit 205 delays the advance angle change of the closing timing IVC of the intake valve 105 during the acceleration operation of the engine 101, and the cylinder charging efficiency ηv determined from the closing timing IVC and the intake pipe pressure PB is obtained. The target intake pipe pressure (target throttle opening TVO) is corrected so as to indicate an increase change.

  A final target value calculation unit 206 calculates final target values (VEL command value, VTC command value, throttle command value) of the electronic control throttle 104, the center phase variable mechanism 113, and the lift / operating angle variable mechanism 112. Output.

Here, details of the processing in the target torque correction unit 205 (delay processing in the present invention) will be described with reference to the flowchart of FIG.
The routine shown in the flowchart of FIG. 7 is executed by interruption every predetermined minute time.

In the flowchart of FIG. 7, first, in step S301, it is determined whether or not the engine 101 is in an acceleration state based on the accelerator opening APO.
Specifically, as shown in FIG. 8, the difference (change amount) ΔAPO (ΔAPO = latest detected value−unit time before) the latest detected value of the accelerator opening APO and the accelerator opening APO detected before unit time. Of the difference (change amount) ΔAPO and the predetermined value A (> 0) are compared by the first comparator 402.

  The first comparator 402 outputs an output when the difference (change amount) ΔAPO is greater than or equal to a predetermined value A, in other words, when the accelerator opening APO is increasing and changing at a speed exceeding the predetermined value A. When the difference (change amount) ΔAPO is less than the predetermined value A, in other words, when the accelerator opening APO is decreasing or when the accelerator opening APO is constant, or the accelerator opening APO is predetermined. When the change is increasing at a speed lower than the value A, the output is set to 0 (low level).

  On the other hand, the second comparator 403 compares the latest detected value of the accelerator opening APO with a predetermined value B, and outputs 1 when the accelerator opening APO is equal to or larger than the predetermined value B (>> fully closed). (High level), and when the accelerator opening APO is less than the predetermined value B, the output is set to 0 (low level).

  A logical sum circuit (OR circuit) 404 receives a binary signal output from the first comparator 402 and a binary signal output from the second comparator 403, and performs a logical sum operation on these outputs. I do.

  Accordingly, when at least one of the binary output of the first comparator 402 and the binary output of the second comparator 403 is 1 (high level), the logical sum circuit (OR circuit) 404 When the output is 1 (high level) and the binary output of the first comparator 402 and the binary output of the second comparator 403 are both 0 (low level), the output is 0 (low level). )become.

  The binary signal output from the logical sum circuit (OR circuit) 404 is an acceleration determination flag indicating the acceleration state of the engine 101, and the output of the logical sum circuit (OR circuit) 404 is 1 (high level). If the output of the logical sum circuit (OR circuit) 404 is 0 (low level), the engine 101 is in a non-accelerated state (deceleration operation or steady operation). ).

In step S301, it is determined whether or not the vehicle is in an acceleration state by determining the acceleration determination flag (output of the logical sum circuit (OR circuit) 404).
That is, in the present embodiment, when the accelerator opening APO is increasing and changing at a speed exceeding the predetermined value A and / or when the accelerator opening APO is equal to or larger than the predetermined value B, the acceleration state of the engine 101 is determined. It is supposed to be considered.

  In the determination based on the accelerator opening APO, it is possible to determine whether or not the acceleration state is based only on the difference ΔAPO, and the acceleration state is determined from a change in the target torque Ttg instead of the accelerator opening APO. Can be determined.

  The predetermined value A and the predetermined value B are appropriately set based on whether or not it is required to perform correction processing for acceleration in step S302 and later, which will be described later. In the case where the correction process is not performed, at least an operation condition (for example, an acceleration state from a low load / low rotation range including an idle operation, etc.) in which an acceleration slack occurs due to a decrease in the transient response of the torque is included. The predetermined value A and the predetermined value B are preliminarily adapted.

  If it is determined in step S301 that the engine 101 is not in the accelerated operation state, the correction processing for acceleration after step S302 is not necessary, so the process bypasses steps S302 to S309 and proceeds to step S310. The target values calculated by the target valve timing calculation unit 202 and the target boost calculation unit 203 are output as final targets, and the electronic control throttle 104, the center phase variable mechanism 113, and the lift / operating angle variable according to the final targets. The mechanism 112 is controlled.

On the other hand, if it is determined in step S301 that the engine 101 is in the accelerated operation state, the process proceeds to step S302.
In step S302, the target torque TtgA during acceleration operation is calculated.

  Specifically, the target torque TtgA that changes along with the torque response required during acceleration is set with reference to the target torque Ttg that is suitable for steady operation calculated by the target torque calculator 201.

  That is, for example, a target torque that changes following a preset response characteristic with respect to a target torque Ttg that increases stepwise due to a step increase of the accelerator opening APO is set as a target torque TtgA for acceleration.

  In the next step S303, based on the acceleration target torque TtgA set in step S302, a target advance value, a target lift / operation angle, and a target intake pipe pressure of the central phase of the valve operation angle are calculated. .

  In step S304, the closing timing IVC of the intake valve 105 at the target lift / operation angle and the target center phase is obtained based on the target advance value and the target lift / operation angle calculated in step S303.

  The closing timing IVC is a crank angle position at which the lift amount becomes zero from the state in which the intake valve 105 is lifted. For example, an angular position at which the valve lift amount decreases and becomes a minute threshold value or less, The closing time IVC can be set.

  In step S305, it is determined whether or not the closing timing IVC obtained in step S304 is before the piston bottom dead center BDC and has changed in the advance direction compared to the previous value.

  For example, when accelerating from a low-speed / low-load operation state such as idle operation, the central phase of the valve operating angle of the intake valve 105 is set to the bottom of the piston while the valve lift amount and valve operating angle of the intake valve 105 remain substantially constant. There is a case where the setting for changing to the advance direction in the crank angle region before the point BDC is temporarily made in the early stage of acceleration.

  This is because driving performance (fuel consumption performance) when the target lift, operating angle, and target center phase according to the engine operating state (target torque Ttg, engine rotational speed NE, etc.) are set to steady operation under individual driving conditions. ), And when the operating state changes with the acceleration operation, for example, it is required under the current operating condition with respect to the closing timing IVC required under the previous operating condition. In some cases, the closing timing IVC is more advanced.

  On the other hand, at the time of acceleration from a low rotation / low load operation state such as idle operation, the intake pipe pressure PB is controlled to increase from the relatively low intake pipe pressure PB required for low load / low rotation. When the increase in the intake pipe pressure PB is slow and the advance timing changes in the region before the piston bottom dead center BDC when the closing timing IVC changes, the cylinder charging efficiency ηv temporarily decreases, and low rotation / There is a problem that the rising response of the torque during acceleration from the low load operation state is deteriorated.

  The advance angle change in the region before the piston bottom dead center BDC at the closing timing IVC in the early stage of acceleration described above is negative because, for example, NOx is reduced due to a decrease in combustion temperature due to an increase in valve overlap in a medium load state. In order to reduce pumping loss and improve fuel efficiency by reducing pressure, the intake valve 105 is quickly closed in a high load state to ensure the intake amount.

FIG. 9 shows the correlation between the closing timing IVC of the intake valve 105 and the cylinder charging efficiency ηv for each intake pipe pressure PB.
As shown in FIG. 9, if the intake pipe pressure PB is the same, the cylinder charging efficiency ηv decreases as the closing timing IVC advances in the region before the bottom dead center BDC.

  Therefore, when the increase in the intake pipe pressure PB in the early stage of acceleration is slow, if the closing timing IVC changes the advance angle before the bottom dead center BDC, the intake pipe pressure PB is filled in the cylinder even though the closing timing IVC is advanced. Since there is no increase change enough to increase the efficiency ηv, a drop in the cylinder charging efficiency ηv occurs, and as a result, the rise of torque during acceleration is delayed.

  In FIG. 9, the change characteristic 500 of the closing timing IVC and the cylinder charging efficiency ηv, in which square symbols are connected by a dotted line, shows the characteristics when the processing of Steps S306 to S309 described later is not performed, and is a low-speed operation such as idle operation. -When the closing timing IVC greatly advances before the bottom dead center BDC during acceleration from the low load operation state (when changing from 500a to 500b), the intake pipe pressure PB increases only slightly. The cylinder charging efficiency ηv once decreases from the acceleration start time, but thereafter, the change in the advance angle of the closing timing IVC becomes dull, while the intake pipe pressure PB shows an increasing change. It shows an increasing change without being depressed.

  In the example shown in FIG. 9, the point 500a is located on the −530 mmHg line, whereas the point 500b is located on the −500 mmHg line, and the intake pipe pressure PB increases (changes close to atmospheric pressure). As shown in the figure, since the increase allowance is small, the cylinder filling efficiency ηv is once reduced from that at the start of acceleration.

  In FIG. 10, a characteristic in which square symbols are connected by a dotted line is a characteristic when processing in steps S306 to S309 described later is not performed, and FIG. 10D illustrates the closing timing IVC at the initial stage of acceleration. The change in the cylinder filling efficiency ηv when the advance angle is changed before the bottom dead center BDC is shown with the horizontal axis as the time axis, and when the processing of steps S306 to S309, which will be described later, is not performed, in the initial stage of acceleration The cylinder filling efficiency ηv once declines and then increases and changes.

  If it is determined in step S305 that the closing timing IVC is changing in the advance direction in front of the piston bottom dead center BDC, based on the setting in step S303, the center phase variable mechanism 113 and the electronic control throttle If 104 is controlled, the torque rise response at the time of acceleration is reduced as described above. Therefore, the process proceeds to steps S306 to S309, and correction control for improving the torque rise response is performed. Do.

  On the other hand, if the closing timing IVC is after the piston bottom dead center BDC and / or changes in the retarding direction, it is determined that the correction control in steps S306 to S309 is unnecessary, and step S306 is performed. Step S309 is bypassed and the process proceeds to Step S310.

  When the closing timing IVC changes in the retarding direction before the piston bottom dead center BDC, it is a change approaching the piston bottom dead center BDC, which is a change in the direction of increasing the cylinder charging efficiency, Further, since the change in the closing timing IVC after the piston bottom dead center BDC increases the engine load and the intake pipe pressure approaches the atmospheric pressure, the torque response does not decrease. It is determined that the correction control in 309 is unnecessary.

When the process proceeds from step S305 to step S310, the target value calculated in step S303 is output as the final target value.
In step S306, correction control of the intake pipe pressure PB is executed.

  The correction control of the intake pipe pressure PB is obtained from the current target intake pipe pressure and the current step S304 rather than the cylinder filling efficiency ηv corresponding to the previous target intake pipe pressure and the closing timing IVC obtained in the previous step S304. The current target intake pipe pressure is corrected and set so that the cylinder charging efficiency ηv corresponding to the closing timing IVC does not fall below.

  For example, referring to the characteristic diagram shown in FIG. 9 from the closing timing IVC obtained in the previous step S304 and the previous target intake pipe pressure, the previous cylinder charging efficiency ηv is obtained and obtained in the current step S304. When the cylinder charging efficiency ηv obtained by referring to the characteristic diagram of FIG. 9 based on the closing timing IVC and the target intake pipe pressure set in step S303 is lower than the previous value, the target intake pipe pressure PB is set to a minute value. Increase correction.

  The increase correction for each minute value is a process for preventing the cylinder charging efficiency ηv corresponding to the corrected target intake pipe pressure PB from excessively increasing from the previous value. The target intake pipe pressure PB that can increase and change the cylinder filling efficiency ηv while the pipe pressure PB is gradually increased is corrected.

Therefore, the minute value is set in advance from the allowance for an increase in the cylinder filling efficiency ηv.
Then, when the cylinder filling efficiency ηv obtained with the corrected target intake pipe pressure PB becomes equal to or higher than the previous value, the correction control of the target intake pipe pressure PB is terminated, and the target intake pipe pressure is determined.

The target intake pipe pressure PB need only be corrected to the minimum necessary to eliminate the drop in cylinder filling efficiency ηv, and the correction method is not limited.
For example, based on a function using a difference (advance change amount) between the previous value and the present value of the closing timing IVC as a variable, a larger correction value is set as the advance angle change amount is larger. The pipe pressure can be increased and corrected.

If the intake pipe pressure is corrected as described above, the intake pipe pressure PB that can suppress the drop in the cylinder charging efficiency ηv with respect to the advance angle change of the closing timing IVC is targeted.
However, the correction of the intake pipe pressure PB can suppress the drop in the cylinder filling efficiency ηv at the initial stage of acceleration, but the intake valve 105 closes IVC while the increase in the intake pipe pressure PB is slow. If this is done, the response to the rise of the torque is slow, and the driver feels that the acceleration is slow.

  On the other hand, if the target intake pipe pressure is greatly increased and corrected so as to increase the intake pipe pressure PB with good response from the early stage of acceleration, the required negative pressure cannot be secured, or if the intake pipe negative pressure is suddenly changed, The measurement accuracy of the intake air amount may be reduced, or an acceleration shock may be caused by a sudden increase in the cylinder intake air amount, and it is difficult to eliminate the feeling of acceleration with only an increase correction of the intake pipe pressure PB. .

  Therefore, in step S307, the advance delay change of the closing timing IVC of the intake valve 105 is caused in a state where the rising delay time of the intake pipe pressure PB in the early stage of acceleration has passed and the intake pipe pressure PB shows a smooth increase change. Then, a delay process for delaying the advance angle change of the closing timing IVC accompanying the acceleration is executed, whereby the cylinder filling efficiency ηv is raised with good response so that the feeling of acceleration can be eliminated.

  Specifically, in step S307, as a delay process for delaying the advance angle change of the closing timing IVC due to acceleration, the center phase change by the center phase variable mechanism 113 (advance angle change of the closing timing IVC) is temporarily stopped. Take control.

As the control for stopping the change of the center phase by the center phase variable mechanism 113, for example, a control for holding the final target value of the center phase at the previous value is performed.
As a result, the timing at which the center phase variable mechanism 113 advances the center phase (closing timing IVC) of the intake valve 105 is delayed, and the closing timing after the intake pipe pressure PB becomes higher and shows a stable increasing trend. The IVC is advanced.

  In step S308, it is determined whether or not the actual intake pipe pressure PB detected by the intake pipe pressure sensor 133 exceeds the threshold value PBSL, and the process returns to step S307 until the actual intake pipe pressure PB exceeds the threshold value PBSL. Control (temporary stop processing) for stopping the change of the center phase by the center phase variable mechanism 113 is continued, and the center phase (closing timing IVC) is kept constant.

  In the present embodiment, as described above, the advance angle change of the closing timing IVC in the initial stage of acceleration is centered by the center phase variable mechanism 113 in a state where the valve lift amount is not changed by the lift / operation angle variable mechanism 112. As the phase is advanced, the process of stopping the change of the center phase by the center phase variable mechanism 113 is performed as described above, and the operation of the lift / operation angle variable mechanism 112 is not limited.

  If it is determined in step S308 that the actual intake pipe pressure PB has exceeded the threshold value PBSL, the intake pipe pressure PB has risen sufficiently, and even if the closing timing IVC has advanced, the cylinder charging efficiency ηv is a response. It is judged that it can stand up well and eliminate the feeling of acceleration.

  Therefore, if it is determined in step S308 that the actual intake pipe pressure PB has exceeded the threshold PBSL, the process proceeds to step S309, where the center phase variable mechanism 113 is allowed to start changing the center phase (changing the advance angle of the closing timing IVC). To do.

  By permitting the start of the change of the center phase (change in the advance angle of the closing timing IVC), the final target advance value of the center phase is changed from the value immediately before the start of the temporary stop process to the current operating state (target It is set so as to gradually approach toward a target according to torque Ttg and engine speed.

In step S310, the final advance value of the central phase of the valve operating angle, the target lift / operating angle, and the target intake pipe pressure are output.
The threshold PBSL used in the step S308 starts the change of the center phase by the center phase variable mechanism 113, and the cylinder filling efficiency even if the closing timing IVC changes the advance angle before the piston bottom dead center BDC. ηv is set as the minimum value of the intake pipe pressure PB that can be raised with good response, and may be a fixed value. However, as shown in FIG. 11, the lower the engine speed NE, the higher the value is set. It is preferable.

  That is, when the engine rotational speed NE is low, the increase in the intake pipe pressure PB becomes dull. Therefore, the advance angle change of the closing timing IVC is caused after the intake pipe pressure PB is increased.

FIG. 12 shows changes in parameters when the correction control in steps S306 to S309 is performed.
The target of the lift / operating angle variable mechanism 112 (VEL) does not change in response to the acceleration request due to the increase in the accelerator opening APO, whereas the target of the center phase by the center phase variable mechanism 113 changes the advance angle.

  Here, as the accelerator opening APO starts increasing, the target of the center phase (closing timing IVC) changes in advance as shown by the dotted line in the figure, but in this embodiment, the start of the advance change is forced. Delayed.

  While the start of the advance change of the center phase (closing timing IVC) is delayed, the throttle opening TVO is controlled to increase so that the intake pipe pressure PB increases and the intake pipe pressure PB exceeds the threshold PBSL. Then, the advance angle change of the center phase (closing timing IVC) is started.

  If the intake pipe pressure PB exceeds the threshold PBSL, even if the closing timing IVC changes the advance angle before the piston bottom dead center BDC, the intake pipe exceeds the decrease in the cylinder filling efficiency ηv due to the advance angle change. The increase in the cylinder filling efficiency ηv due to the increase in the pressure PB is large, and as a result, the cylinder filling efficiency ηv rises with better response than when the delay process indicated by the dotted line in the figure is not performed.

  The change characteristic of the cylinder filling efficiency ηv when the delay processing of step S306 to step S309 is executed is shown in FIG. 9 as a characteristic 502 in which circles are connected by a solid line. As the intake pipe pressure PB increases and changes without being greatly advanced, the cylinder charging efficiency ηv increases, and then the closing timing IVC is advanced under the condition that the intake pipe pressure PB increases and changes. Therefore, the cylinder filling efficiency ηv increases gradually without dropping, and the torque response during acceleration is improved.

  In step S308, it is determined whether or not the intake pipe pressure PB exceeds the threshold value PBSL. Instead, after the delay processing duration T exceeds the threshold value TSL, the central phase by the central phase variable mechanism 113 is determined. (The advance angle change of the closing timing IVC) can be allowed, and the threshold value TSL can be a fixed value, or can be set to a longer time as the engine speed NE is lower.

  In the above embodiment, the delay process for delaying the start of change of the center phase (start of advance of the closing timing IVC) by the center phase variable mechanism 113 is performed. However, as the delay process, the target value of the center phase is smoothed. Processing can be performed.

  When the annealing process is performed, the process in step S307 may be replaced with the center phase target value annealing process, and the process in step S309 may be replaced with stop of the annealing process.

  In the annealing process, for example, a first-order lag process whose input / output relationship is represented by a first-order lag transfer function may be performed on the target value of the center phase, and more specifically, the target value of the center phase. Is weighted average (moving average), or the signal / data of the target value of the center phase is passed through a low-pass filter, and the annealing process may be either analog or digital processing.

  If the annealing process is performed, as shown in FIG. 10 and FIG. 13, since the change in the advance angle of the closing timing IVC is small when the increase in the intake pipe pressure PB at the initial stage of acceleration is slow, the rise of the cylinder charging efficiency ηv is increased. Response can be improved and torque response during acceleration is improved.

  Further, a characteristic obtained by connecting the circles in FIG. 10 with a solid line is a characteristic when the annealing process is executed, and the advance value of the center phase and the advance angle change of the closing timing IVC are delayed by the annealing process. Thus, the intake pipe pressure PB when the closing timing IVC is advanced is relatively higher, and the cylinder charging efficiency ηv shows a rising response.

  The center phase changing mechanism 113 delays the start of changing the center phase (start of advancement of the closing timing IVC) and the smoothing process. For example, the center phase starts changing (closed) for a predetermined time from the beginning of acceleration. The center phase variable mechanism 113 (variable valve mechanism) can be controlled based on the target center phase subjected to the annealing process after delaying the advance of the timing IVC).

  Also, when the closing timing IVC of the intake valve 105 is advanced by the change of the center phase by the center phase variable mechanism 113 and the change of the valve lift amount and the valve operation angle by the lift / operating angle variable mechanism 112 at the initial stage of acceleration. In this configuration, a delay process is applied to at least one of the target value of the center phase and the target value of the lift amount / operating angle, thereby delaying the advance change of the closing timing IVC to an extent that can improve the torque response. be able to.

Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) In the control apparatus for a variable valve mechanism according to claim 1 or 2 ,
A control apparatus for a variable valve mechanism, wherein the predetermined pressure is variably set based on an engine speed.

According to the above invention, when the engine speed is low, the intake pipe pressure rises dull, so that the valve timing (closing timing) is changed after the intake pipe pressure rises to a higher level. In addition, the predetermined pressure is variably set based on the rotational speed of the engine.
(B) In the control device for a variable valve mechanism according to any one of claims 1, 2, and (a) ,
As the process of delaying the change of the valve timing, a smoothing process is performed on the target valve timing set based on the operating state of the engine, and the variable valve mechanism is based on the target valve timing subjected to the smoothing process A control apparatus for a variable valve mechanism that controls the valve.

According to the above invention, the target valve timing is subjected to the smoothing process, and the variable valve mechanism is controlled based on the target valve timing that has been subjected to the smoothing process. The change can be delayed and the valve timing changed under a relatively high intake pipe pressure .

  DESCRIPTION OF SYMBOLS 3 ... Intake camshaft, 13 ... Control shaft, 99 ... Electromagnetic actuator, 101 ... Internal combustion engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 107 ... Exhaust valve, 112 ... Lift / working angle variable mechanism, 113 ... Center phase Variable mechanism, 114 ... engine control unit, 116 ... accelerator pedal sensor, 117 ... crank angle sensor, 120 ... crankshaft, 132 ... intake cam sensor, 133 ... intake pipe pressure sensor, 134 ... angle sensor

Claims (2)

A control device for a variable valve mechanism that controls a variable valve mechanism that varies a valve timing of an intake valve of an engine according to an operating state of the engine,
Control of the variable valve mechanism for stopping the change of the valve timing or delaying the change of the valve timing with respect to the change of the operating state of the engine until the intake pipe pressure from the start of acceleration of the engine reaches a predetermined pressure apparatus. A control device for a variable valve mechanism that controls a variable valve mechanism that varies a valve timing of an intake valve of an engine according to an operating state of the engine,
Until the intake pipe pressure from the start of acceleration of the engine reaches a predetermined pressure, the advance angle before the bottom dead center of the closing timing of the intake valve is stopped or the change of the operation state of the engine A control device for a variable valve mechanism that delays the advance angle change before the bottom dead center of the closing time and changes the close time according to a change in the operating state of the engine except for the advance angle before the bottom dead center .

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