JP2010159692A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine reducing both heat generation amount and power consumption of a variable lift mechanism during fuel cut operation in the case of changing the maximum head of an opened intake valve by the variable lift mechanism. <P>SOLUTION: In the internal combustion engine 3, an intake lift Liftin which is the maximum head of the opened intake valve 4 can continuously be changed by the variable lift mechanism 40 within a predetermined range (Liftin_min to Liftin_max), and when electric power supply to an electric motor 48 of the variable lift mechanism 40 is stopped, the intake lift Liftin is mechanically held at a predetermined value Liftin_ref by a lift holding mechanism 50. The control device 1 includes an ECU 2, and the ECU 2 determines whether it is in fuel cut operation or not (step 1). When it is in fuel cut operation, the electric power supply to the electric motor 48 is stopped (step 3). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine in which a maximum lift during opening of an intake valve is continuously changed within a predetermined range by a variable lift mechanism.

  Conventionally, what was described in patent document 1 is known as a control apparatus of an internal combustion engine. This internal combustion engine includes a variable lift mechanism, and the variable lift mechanism changes the intake lift, which is the maximum lift during the opening of the intake valve, into a plurality of stages by switching a plurality of cams ( Paragraph [0019]).

  In this control device, it is determined whether or not the deceleration fuel cut operation of the internal combustion engine is being performed, and when the deceleration fuel cut operation is being performed, the intake lift is forcibly reduced to its minimum value by controlling the variable lift mechanism. (Paragraphs [0021] and [0022], steps 1 and 2 in FIG. 3). This is because the atmosphere of the pressure sensor that detects the pressure in the intake system is set to atmospheric pressure by suppressing the negative pressure in the cylinder from acting on the intake system side (paragraph [0026]).

JP-A-9-250373

  According to the above-described conventional control device for an internal combustion engine, the variable lift mechanism is controlled to reduce the intake lift to the minimum value during the deceleration fuel cut operation. During this time, it is necessary to supply power to the variable lift mechanism. As a result, the variable lift mechanism generates heat and the power consumption increases.

  The present invention has been made to solve the above-described problem, and in the case where the maximum lift during opening of the intake valve is changed by the variable lift mechanism, the heat generation amount and power consumption of the variable lift mechanism during the fuel cut operation. It is an object of the present invention to provide a control device for an internal combustion engine that can reduce both of the amounts.

  In order to achieve the above object, the invention according to claim 1 is configured such that the intake lift Liftin, which is the maximum lift during the opening of the intake valve 4, is controlled by the variable lift mechanism 40 using the electric motor 48 as a power source. The intake lift Liftin is lift-maintained when the electric power supply to the electric motor 48 is stopped and the power supply to the electric motor 48 is stopped while being configured to be continuously changeable within a predetermined range defined by the value Liftin_max and the predetermined minimum value Liftin_min. A control device 1 for an internal combustion engine 3 that is mechanically held at a predetermined value (predetermined value Liftin_ref, predetermined maximum value Liftin_max) within a predetermined range by a mechanism 50, 50A, and stops the supply of fuel to the internal combustion engine 3 Determining means (ECU2, step 1) for determining whether or not the fuel cut operation is being performed, Control means (ECU2, step 3) for stopping the power supply to the electric motor 48 when the fuel cut operation is being performed based on the fixed result (when the determination result of step 1 is YES). Features.

  According to the control device for the internal combustion engine, when the fuel cut operation is being performed based on the determination result of the determination unit, the power supply to the electric motor of the variable lift mechanism is stopped, and accordingly, the intake lift is operated by the lift holding mechanism. Is mechanically held at a predetermined value within a predetermined range. In this way, during the fuel cut operation, the intake lift can be mechanically held at a predetermined value without supplying electric power to the electric motor. Therefore, compared with the conventional case of controlling the variable lift mechanism, the fuel cut Both the calorific value and power consumption of the variable lift mechanism during operation can be reduced.

  According to a second aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the first aspect, the predetermined value Liftin_ref is a value within a predetermined range excluding the predetermined maximum value Liftin_max and the predetermined minimum value Liftin_min. Features.

  According to this control device for an internal combustion engine, during the fuel cut operation, the intake lift is mechanically held at a value within a predetermined range excluding the predetermined maximum value and the predetermined minimum value. Compared with the case where the value is maintained, it is possible to suppress the oil rise caused by the negative pressure in the cylinder and to further increase the rotational resistance acting on the crankshaft of the internal combustion engine. Thus, when the internal combustion engine is a power source of the vehicle and the vehicle is decelerating, a larger engine braking force can be ensured than when the intake lift is held at a predetermined minimum value.

  The invention according to claim 3 is the control apparatus 1 for the internal combustion engine 3 according to claim 1, wherein the predetermined value is a predetermined maximum value Liftin_max.

  In the case of an internal combustion engine with a variable lift mechanism, during a high load operation, the variable lift mechanism is generally controlled so that the intake lift becomes a predetermined maximum value within a predetermined range in order to ensure high output. . On the other hand, according to the control device for the internal combustion engine, when the power supply to the electric motor is stopped, the internal combustion engine is mechanically held at a predetermined maximum value by the lift holding mechanism. Even during operation, the power supply to the electric motor of the variable lift mechanism can be stopped. Thereby, during high load operation, both the amount of heat generated and the power consumption of the variable lift mechanism can be reduced, and the variable lift mechanism can be prevented from becoming a load on the internal combustion engine. The output can be improved.

  According to a fourth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to any one of the first to third aspects, the internal combustion engine 3 is mounted on the vehicle as a power source and opens and closes the intake passage 12. An electric intake passage valve (throttle valve 13a) is provided, and when the internal combustion engine 3 is in the fuel cut operation, the control means turns the intake passage valve into the intake passage valve in addition to stopping power to the electric motor 48. Control is performed so that the opening (throttle valve opening TH) becomes a predetermined minimum opening THmin (steps 1 to 3).

  According to this control device for an internal combustion engine, the internal combustion engine is mounted on a vehicle as a power source, and includes an electrically driven intake passage valve that opens and closes the intake passage, and when the internal combustion engine is in a fuel cut operation, In addition to stopping power to the motor, the intake passage valve is controlled so that its opening degree is a predetermined minimum opening degree, so when the internal combustion engine is in fuel cut operation and the vehicle is running at a reduced speed Sufficient engine braking force can be secured.

It is a figure showing the schematic structure of the internal-combustion engine to which the control device concerning one embodiment of the present invention is applied. It is a figure which shows schematic structure of a control apparatus. It is a figure which shows schematic structure of an intake side valve mechanism. It is a perspective view which shows schematic structure of a variable lift mechanism. It is a perspective view which shows schematic structure of the link mechanism of a variable lift mechanism. It is a figure which shows schematic structure of the lift actuator of a variable lift mechanism, Comprising: It is a figure which respectively shows the state in which a lift actuator is in the state (a) maximum lift position and (b) minimum lift position. FIG. 2 is a schematic diagram showing a schematic configuration of a lift holding mechanism, in which a control shaft (a) is in a default position, (b) is in a maximum lift position, and (c) is in a minimum lift position. is there. It is a figure which shows the change of the valve lift curve accompanying the change of the intake lift by a variable lift mechanism. It is a schematic diagram which shows schematic structure of a variable cam phase mechanism. The figure which each shows the valve lift curve of an intake valve, and the valve lift curve of an exhaust valve when the cam phase is set to the most retarded angle value (solid line) and the most advanced angle value (two-dot chain line) by the variable cam phase mechanism It is. It is a flowchart which shows an intake air amount control process. It is a flowchart which shows a fuel-injection control process. It is a schematic diagram which shows schematic structure of the modification of a lift holding | maintenance mechanism.

  Hereinafter, an internal combustion engine control apparatus according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, the control device 1 includes an ECU 2. As will be described later, the ECU 2 performs an intake air amount control process in accordance with an operating state of an internal combustion engine (hereinafter referred to as “engine”) 3. And various control processes including a fuel injection control process.

  As shown in FIG. 1, the engine 3 is an in-line four-cylinder gasoline engine having four sets of cylinders 3a and pistons 3b (only one set is shown), and is mounted on a vehicle (not shown).

  The engine 3 has a pair of intake valves 4 and 4 (see FIG. 5) and a pair of exhaust valves 7 and 7 (only one is shown), an intake camshaft 5 and an intake cam 6 provided for each cylinder 3a. An intake side valve mechanism 30 that opens and closes each intake valve 4, an exhaust side valve mechanism 70 that has an exhaust camshaft 8 and an exhaust cam 9 and drives each exhaust valve 7 to open and close, and a fuel injection valve 10 (FIG. 2). And a spark plug 11 (see FIG. 2).

  Each of the intake camshaft 5 and the exhaust camshaft 8 is rotatably attached to the cylinder head 3c via a holder (not shown) and extends along the arrangement direction of the cylinders 3a. An intake sprocket (not shown) is coaxially disposed on one end of the intake camshaft 5 and is rotatably provided. The intake sprocket is connected to the crankshaft 3d via a timing chain (not shown), and is connected to the intake camshaft 5 via a variable cam phase mechanism 60 described later. With the above configuration, the intake camshaft 5 rotates once every time the crankshaft 3d rotates twice. The intake cam 6 is provided on the intake camshaft 5 so as to rotate integrally therewith.

  Further, the intake side valve mechanism 30 is configured to open and close the intake valve 4 of each cylinder 3a against the urging force of the return spring 4a by the rotation of the intake camshaft 5 accompanying the rotation of the crankshaft 3d. As will be described later, the intake valve 4 is configured with a variable valve mechanism that continuously changes the intake lift, which is the maximum lift during the opening of the intake valve 4, and continuously changes the valve timing of the intake valve 4. Yes.

  On the other hand, an exhaust sprocket (not shown) is coaxially disposed on one end of the exhaust camshaft 8 and is rotatably provided. The exhaust sprocket is connected to the crankshaft 3d via a timing chain (not shown). With the above configuration, the exhaust camshaft 8 rotates once every time the crankshaft 3d rotates twice. Further, the exhaust cam 9 is provided for each cylinder 3a on the exhaust camshaft 8 so as to rotate integrally therewith.

  Further, the exhaust-side valve mechanism 70 opens and closes the exhaust valve 7 of each cylinder 3a against the urging force of the return spring 7a by the rotation of the exhaust camshaft 8 accompanying the rotation of the crankshaft 3d. During the exhaust stroke, the exhaust valve 7 is opened so that the combustion gas is discharged from the cylinder 3a into the exhaust passage 14.

  On the other hand, the fuel injection valve 10 is provided for each cylinder 3a, and is attached to the cylinder head 3c so as to inject fuel directly into the cylinder 3a. That is, the engine 3 is configured as a direct injection engine. The fuel injection valve 10 is electrically connected to the ECU 2, and the valve opening time and the valve opening timing are controlled by the ECU 2 based on a fuel injection amount TOUT described later. That is, the fuel injection time and the injection timing are controlled.

  A spark plug 11 is also provided for each cylinder 3a and attached to the cylinder head 3c. The spark plug 11 is electrically connected to the ECU 2, and the discharge state is controlled by the ECU 2 so that the air-fuel mixture in the cylinder is combusted at a timing corresponding to the ignition timing.

  Further, the engine 3 is provided with a crank angle sensor 20. The crank angle sensor 20 includes a magnet rotor and an MRE pickup, and outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3d rotates.

  The CRK signal is output at one pulse every predetermined crank angle (for example, 1 °), and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly ahead of the TDC position of the intake stroke, and one pulse is output for each predetermined crank angle.

  On the other hand, a throttle valve mechanism 13 is provided in the intake passage 12 of the engine 3, and this throttle valve mechanism 13 includes a throttle valve 13 a and a TH actuator 13 b that opens and closes the throttle valve 13 a. The throttle valve 13a is rotatably provided in the intake passage 12, and changes the fresh air flow rate in the intake passage 12 by changing the opening degree accompanying the rotation. The TH actuator 13b is a combination of a motor connected to the ECU 2 and a gear mechanism (both not shown), and is driven by a TH control input U_TH described later from the ECU 2, thereby opening the throttle valve 13a. To change. In the present embodiment, the throttle valve 13a corresponds to the intake passage valve, and the throttle valve opening TH corresponds to the opening of the intake passage valve.

  Next, the intake side valve mechanism 30 described above will be described with reference to FIG. As shown in the figure, the intake side valve mechanism 30 includes an intake camshaft 5, an intake cam 6, a variable lift mechanism 40, a lift holding mechanism 50 (see FIG. 7), a variable cam phase mechanism 60, and the like. .

  The variable lift mechanism 40 opens and closes the intake valve 4 by the rotation of the intake camshaft 5 accompanying the rotation of the crankshaft 3d, and the intake lift Liftin is not between the minimum value Liftin_min and the maximum value Liftin_max shown in FIG. It is to change to the stage. 4 and 5, the variable lift mechanism 40 includes a control shaft 41 and a rocker arm shaft 42, a rocker arm mechanism 43 provided on the shafts 41 and 42 for each cylinder 3a, and these rocker arm mechanisms 43. A lift actuator 47 (see FIG. 6) that is driven simultaneously is provided.

  The control shaft 41 is an assembly of a rotating shaft portion 41a, a holder portion 41b, and an eccentric shaft portion 41c. The control shaft 41 extends along the intake camshaft 5, and the rotating shaft portion 41a is a holder for the cylinder head 3c (see FIG. (Not shown) is rotatably held, and one end thereof is connected to the lift actuator 47.

  On the other hand, each rocker arm mechanism 43 is a combination of upper and lower rocker arms 44, 45. The upper rocker arm 44 includes a pair of links 44a, 44a, a roller shaft 44b, a roller 44c, and a pair of coil springs 44d, 44d. ing. Both ends of the roller shaft 44b are attached to one ends of the links 44a and 44a, respectively, and are rotatably supported by the links 44a and 44a. The roller 44c is rotatably provided on the roller shaft 44b.

  The other end of each link 44a is rotatably attached to an eccentric shaft portion 41c of the control shaft 41, and is connected to the holder portion 41b via a coil spring 44d. In the link 44a, the roller 44c is brought into contact with the cam surface of the intake cam 6 by the biasing force of the coil spring 44d, and when the roller 44c is in contact with the base circle of the cam surface of the intake cam 6, the roller shaft 44b. Is held at the origin position (position shown in FIG. 3) such that its axis is located on the axis of the rotation shaft portion 41a.

  On the other hand, one end of the lower rocker arm 45 is rotatably supported by the rocker arm shaft 42, and adjustment bolts 45a and 45a are attached to the other end, and the adjustment bolts 45a and 45a are used to respectively It is in contact with the upper end of the intake valve 4.

  The lower rocker arm 45 includes a pair of guide portions 45b and 45b protruding upward. The upper surface of each guide portion 45b is a guide surface 45c for guiding the roller shaft 44b of the upper rocker arm 44, and abuts against the roller shaft 44b via the guide surface 45c by the urging force of the return spring 4a. . The guide surface 45c has a downwardly convex arc shape. Further, in a state where the guide portion 45b and the roller shaft 44b are in contact with each other, the roller 44c is positioned between the guide portions 45b and 45b and contacts only the intake cam 6 without contacting the lower rocker arm 45.

  On the other hand, as shown in FIG. 6, the lift actuator 47 described above includes an electric motor 48 and a reduction gear mechanism 49. The electric motor 48 is electrically connected to the ECU 2 (see FIG. 2), and when driven by a later-described lift control input U_Liftin from the ECU 2, the rotary shaft 48a is rotated forward / reversely.

  The reduction gear mechanism 49 is a combination of a worm 49 a and a sector gear type worm wheel 49 b, and the worm 49 a is fixed concentrically on the rotating shaft 48 a of the electric motor 48. Thereby, the worm 49a rotates integrally with the rotating shaft 48a.

  On the other hand, the worm wheel 49 b is bolted to one end of the control shaft 41 so that the rotation center thereof coincides with the rotation center of the control shaft 41. Further, the worm 49a and the worm wheel 49b are arranged so that their rotational centers are orthogonal to each other in a state where they mesh with each other, and the advance angle of the worm 49a is set to be larger than the friction angle. . Thus, in this reduction gear mechanism 49, the worm wheel 49b rotates with the rotation of the worm 49a, and the worm 49a rotates with the rotation of the worm wheel 49b.

  In the lift actuator 47 described above, when the electric motor 48 is driven by the ECU 2, the control shaft 41 is rotated against an urging force of coil springs 52 and 53 described later of the lift holding mechanism 50. At this time, the worm wheel 49b abuts against a stopper (not shown), so that the rotation angle range of the control shaft 41 is the maximum lift position shown in FIG. 6A and the minimum lift position shown in FIG. 6B. Be regulated between. As a result, the rotation range of the link 44a is also the maximum lift position shown in FIG. 6A (the position indicated by the two-dot chain line in FIG. 3) and FIG. ) To the minimum lift position (position indicated by a solid line in FIG. 3).

  Further, as shown in FIG. 7, the lift holding mechanism 50 described above includes an arm 51 and two coil springs 52 and 53. The arm 51 has a base end fixed to the control shaft 41, and is configured to rotate integrally with the control shaft 41.

  Further, both ends of the coil spring 52 are fixed to the distal end portion of the arm 51 and the mounting portion 54 of the cylinder head 3c, respectively, and are provided in a compressed state between the arm 51 and the mounting portion 54. Further, both end portions of the coil spring 53 are fixed to the tip end portion of the arm 51 and the mounting portion 55 of the cylinder head 3 c, respectively, and are provided in a compressed state between the arm 51 and the mounting portion 55.

  When the power supply to the electric motor 48 of the lift actuator 47 is stopped, that is, when a lift control input U_Liftin described later is not input from the ECU 2, the lift holding mechanism 50 is activated by the biasing force of the coil springs 52 and 53. The control shaft 41 is held at the default position shown in FIG.

  Next, operations of the variable lift mechanism 40 and the lift holding mechanism 50 configured as described above will be described. First, when the lift control input U_Liftin from the ECU 2 is input to the electric motor 48 of the lift actuator 47, the electric motor 48 moves the control shaft 41, that is, the link 44a, against the urging force of the coil springs 52 and 53. After driving to a position corresponding to the lift control input U_Liftin between the maximum lift position shown in FIG. 7B and the minimum lift position shown in FIG. 7C, the position is held at that position.

  For example, when the link 44a is held at the minimum lift position (the position indicated by the solid line in FIG. 3), when the intake cam 6 rotates, the link 44a rotates about the eccentric shaft portion 41c in the clockwise direction in FIG. Then, the lower rocker arm 45 is pushed downward. As a result, the lower rocker arm 45 rotates downward from the valve closing position shown in FIG. 3 while resisting the urging force of the return spring 4 a to open the intake valve 4. At that time, the intake valve 4 is opened in accordance with a valve lift curve indicated by a one-dot chain line in FIG. 8, and the intake lift Liftin indicates the minimum value Liftin_min.

  On the other hand, in a state where the link 44a is held at a position closer to the maximum lift position than the minimum lift position, the link 44a rotates about the eccentric shaft portion 41c in the clockwise direction by the rotation of the intake cam 6. The lower rocker arm 45 rotates downward from the minimum lift position shown in FIG. 3 while opening the intake valve 4 while resisting the biasing force of the return spring 4a. At that time, the rotation amount of the lower rocker arm 45, that is, the intake lift Liftin becomes larger as the link 44a is closer to the maximum lift position.

  For the above reasons, the intake valve 4 opens with a larger lift as the link 44a is closer to the maximum lift position. Specifically, during the rotation of the intake cam 6, when the link 44a is at the maximum lift position, the intake valve 4 opens according to the valve lift curve shown by the solid line in FIG. 8, and the intake lift Liftin has its maximum value Liftin_max. Indicates. As described above, in the variable lift mechanism 40, the intake lift Liftin is set to the minimum value Liftin_min and the maximum value by rotating the link 44a between the minimum lift position and the maximum lift position via the lift actuator 47. It can be changed steplessly within a range defined by Liftin_max.

  Further, when the link 44a is at the maximum lift position shown in FIG. 7B, when the power supply to the electric motor 48 of the lift actuator 47 is stopped, that is, the lift control input U_Liftin from the ECU 2 is input to the electric motor 48. When the input is stopped, the control shaft 41, that is, the link 44a is moved from the maximum lift position shown in FIG. 7B to the default position shown in FIG. 7A by the urging force of the coil springs 52 and 53 of the lift holding mechanism 50. Driven and held in this default position. Similarly, when the link 44a is at the minimum lift position shown in FIG. 7C, when the power supply to the electric motor 48 of the lift actuator 47 is stopped, the coil springs 52 and 53 of the lift holding mechanism 50 are stopped. Due to the urging force, the link 44a is driven from the minimum lift position shown in FIG. 7 (c) to the default position shown in FIG. 7 (a) and held in this default position.

  In this way, when the intake cam 6 rotates while the link 44a is held at the default position, the intake valve 4 opens according to the valve lift curve shown by the broken line in FIG. 8, and the intake lift Liftin is a predetermined value. It becomes the value Liftin_ref. The predetermined value Liftin_ref is set so that Liftin_min <Liftin_ref <Liftin_max is established, and the intake lift Liftin is held at the minimum value Liftin_min when the vehicle is traveling at a reduced speed and the fuel cut operation of the internal combustion engine is performed. Compared to the time, the oil rise due to the negative pressure in the cylinder 3a can be suppressed, and the rotational resistance acting on the crankshaft 3d of the engine 3 can be further increased. .

  Further, the variable lift mechanism 40 is provided with a rotation angle sensor 21 (see FIG. 2). The rotation angle sensor 21 detects a rotation angle of the control shaft 41, and a detection signal indicating it. Is output to the ECU 2. The ECU 2 calculates the intake lift Liftin based on the detection signal of the rotation angle sensor 21.

  Next, the variable cam phase mechanism 60 will be described with reference to FIG. The variable cam phase mechanism 60 changes the relative phase (hereinafter referred to as “cam phase”) Cain of the intake camshaft 5 with respect to the crankshaft 3d to the advance side or the retard side steplessly. It is provided at the end of the shaft 5 on the intake sprocket side. As shown in FIG. 9, the variable cam phase mechanism 60 includes a housing 61, a three-blade vane 62, a hydraulic pump 63, a cam phase electromagnetic valve 64, and the like.

  The housing 61 is configured integrally with an intake sprocket on the intake camshaft 5 and includes three partition walls 61a formed at equal intervals. The vane 62 is coaxially attached to the end of the intake camshaft 5 on the intake sprocket side, extends radially outward from the intake camshaft 5, and is rotatably accommodated in the housing 61. In the housing 61, three advance chambers 65 and three retard chambers 66 are formed between the partition wall 61 a and the vane 62.

  The hydraulic pump 63 is a mechanical type connected to the crankshaft 3d. When the crankshaft 3d rotates, along with this, the lubricating oil stored in the oil pan 3e of the engine 3 is supplied to the oil passage 67c. And is supplied to the cam phase solenoid valve 64 via the oil passage 67c in a state where the pressure is increased.

  The cam phase solenoid valve 64 is a combination of a spool valve mechanism 64a and a solenoid 64b, and is connected to the advance chamber 65 and the retard chamber 66 through the advance oil passage 67a and the retard oil passage 67b, respectively. In addition, the hydraulic pressure Poil supplied from the hydraulic pump 63 is output to the advance chamber 65 and the retard chamber 66 as the advance hydraulic pressure Pad and the retard hydraulic pressure Prt, respectively. The solenoid 64b of the cam phase electromagnetic valve 64 is electrically connected to the ECU 2, and when driven by a phase control input U_Cain described later from the ECU 2, the spool valve body of the spool valve mechanism 64a is within a predetermined movement range. By moving, both the advance hydraulic pressure Pad and the retard hydraulic pressure Prt are changed.

  In the variable cam phase mechanism 60 described above, during the operation of the hydraulic pump 63, the cam phase solenoid valve 64 operates in accordance with the phase control input U_Cain from the ECU 2, whereby the advance hydraulic pressure Pad is retarded to the advance chamber 65. The hydraulic pressure Prt is supplied to each of the retard chambers 66, whereby the relative phase between the vane 62 and the housing 61 is changed to the advance side or the retard side. As a result, the aforementioned cam phase Cain continuously changes between a predetermined maximum retardation value and a predetermined maximum advance value, whereby the valve timing of the intake valve 4 is shown by a solid line in FIG. The timing is changed steplessly between the most retarded timing and the most advanced timing shown by a two-dot chain line in FIG.

  As shown in the figure, when the valve timing of the intake valve 4 is set to the most retarded timing, the valve opening timing of the intake valve 4 is later than the valve closing timing of the exhaust valve 7 and the TDC position of the intake stroke. It becomes later timing. As a result, there is no valve overlap between the intake valve 4 and the exhaust valve 7.

  On the other hand, a cam angle sensor 22 (see FIG. 2) is provided at the end of the intake camshaft 5 opposite to the variable cam phase mechanism 60. The cam angle sensor 22 is composed of, for example, a magnet rotor and an MRE pickup, and outputs a CAM signal, which is a pulse signal, to the ECU 2 every predetermined cam angle (for example, 1 °) as the intake camshaft 5 rotates. . The ECU 2 calculates the cam phase Cain based on this CAM signal and the above-described CRK signal.

  As described above, in the engine 3, the intake lift Liftin can be changed steplessly within a predetermined range by the variable lift mechanism 40, and the valve timing of the intake valve 4 is not changed within the predetermined range by the variable cam phase mechanism 60. It is configured so that it can be changed in stages.

  Further, an accelerator opening sensor 23 and a throttle valve opening sensor 24 are connected to the ECU 2. The accelerator opening sensor 23 detects an accelerator opening AP, which is an operation amount of an accelerator pedal (not shown), and outputs a detection signal representing it to the ECU 2. The throttle valve opening sensor 24 is composed of a potentiometer, detects the opening TH of the throttle valve 13a (hereinafter referred to as “throttle valve opening”) TH, and outputs a detection signal representing it to the ECU 2.

  On the other hand, the ECU 2 is composed of a microcomputer including a CPU, RAM, ROM, an I / O interface (all not shown), and the engine 2 according to the detection signals of the various sensors 20 to 24 described above. 3 is determined, and various control processes such as an intake air amount control process and a fuel injection control process are executed. In the present embodiment, the ECU 2 corresponds to a determination unit and a control unit.

  Next, the intake air amount control process described above will be described with reference to FIG. As described below, this control process calculates three control inputs U_TH, U_Liftin, U_Cain, and is executed in a predetermined control cycle (for example, 10 msec). In this process, first, in step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), it is determined whether or not the fuel cut operation flag F_FC is “1”.

The fuel cut operation flag F_FC is set to “1” when both of the following fuel cut operation execution conditions (f1) and (f2) are satisfied, and to “0” when they are not satisfied.
(F1) The engine speed NE is equal to or higher than a predetermined fuel cut speed (for example, 800 rpm).
(F2) The accelerator opening AP is equal to or less than a predetermined opening (for example, value 0).

  When the determination result in step 1 is YES, it is determined that the intake air amount control process for fuel cut operation should be executed, and the process proceeds to step 2, and the TH control input U_TH is set to a predetermined fuel cut operation value U_THFC. Set. Then, the TH control input U_TH is supplied to the TH actuator 13b, whereby the throttle valve opening TH is controlled to a predetermined minimum opening THmin that is almost fully closed. As a result, the intake passage 12 is in a negative pressure state. The predetermined minimum opening THmin is set to such a value that sufficient engine braking can be obtained when the vehicle is decelerating and during fuel cut operation.

  Next, in step 3, the lift control input U_Liftin is set to 0. Thus, when the lift control input U_Liftin is set to the value 0, the power supply to the electric motor 48 of the lift actuator 47 is stopped. Thereby, the lift lift mechanism 50 holds the intake lift Liftin at the predetermined value Liftin_ref described above.

  Next, the process proceeds to step 4 where the phase control input U_Cain is set to a predetermined fuel cut operation value U_CainFC, and then this process is terminated. The phase control input U_Cain is supplied to the cam phase solenoid valve 64 of the variable cam phase mechanism 60, whereby the cam phase Cain is controlled to the most retarded value. As a result, the valve timing of the intake valve 4 is controlled to the most retarded timing described above.

  On the other hand, when the determination result in step 1 is NO, it is determined that the intake air amount control process for normal operation should be executed, and the process proceeds to step 5 to execute the throttle valve opening control process for normal operation. . In this process, the target throttle valve opening THcmd is calculated according to the operating state parameters such as the engine speed NE and the accelerator opening AP, and the throttle valve opening TH and the target throttle valve opening are determined by a predetermined feedback control algorithm. The TH control input U_TH is calculated so that the deviation from THcmd converges to the value 0. The TH control input U_TH is supplied to the TH actuator 13b, so that the throttle valve opening TH is feedback controlled so as to converge to the target throttle valve opening THcmd.

  Next, the routine proceeds to step 6 where an intake lift control process for normal operation is executed. In this process, the target intake lift Liftin_cmd is calculated in accordance with the operating state parameters such as the engine speed NE and the accelerator pedal opening AP, and the deviation between the intake lift Liftin and the target intake lift Liftin_cmd is determined by a predetermined feedback control algorithm. A lift control input U_Liftin is calculated so as to converge to zero. The lift control input U_Liftin is supplied to the electric motor 48 of the lift actuator 47, so that the intake lift Liftin is feedback-controlled so as to converge to the target intake lift Liftin_cmd.

  Next, in step 7, intake lift control processing for normal operation is executed. In this process, the target cam phase Cain_cmd is calculated according to the operating state parameters such as the engine speed NE and the accelerator pedal opening AP, and the deviation between the cam phase Cain and the target cam phase Cain_cmd is determined by a predetermined feedback control algorithm. The phase control input U_Cain is calculated so as to converge to zero. Then, the phase control input U_Cain is supplied to the cam phase electromagnetic valve 64 of the variable cam phase mechanism 60, whereby feedback control is performed so that the cam phase Cain converges to the target cam phase Cain_cmd. As described above, after step 7 is executed, the present process is terminated.

  In the intake air amount control process, as described above, the throttle valve opening TH, the intake lift Liftin, and the cam phase Cain are respectively controlled, thereby controlling the intake air amount.

  Next, the above-described fuel injection control process will be described with reference to FIG. As will be described below, this control process calculates the fuel injection amount of the fuel injection valve 10 and its injection timing, and is executed in a control cycle synchronized with the generation of the TDC signal.

  In this control process, first, in step 10, it is determined whether or not the fuel cut operation flag F_F_FC described above is “1”. When the determination result is YES, it is determined that the fuel injection control process for the fuel cut operation should be executed, the process proceeds to step 11, the fuel injection amount TOUT is set to the value 0, and then this process ends. . When the fuel injection amount TOUT is set to the value 0 in this way, the fuel injection into the cylinder 3a by the fuel injection valve 10 is stopped.

  On the other hand, when the determination result of step 10 is NO, it is determined that the fuel injection control process for normal operation should be executed, the process proceeds to step 12, and the fuel injection control process for normal operation is executed. In the fuel injection control process for normal operation, the fuel injection amount TOUT is calculated according to the operation state parameters such as the engine speed NE and the accelerator pedal opening AP, and the fuel injection amount TOUT and the engine speed NE are determined. Thus, the fuel injection timing is calculated. When the fuel injection amount TOUT and the fuel injection timing are calculated in this way, based on these, fuel is injected from the fuel injection valve 10 into the cylinder 3a. After executing step 12 as described above, the present process is terminated.

  As described above, according to the control device 1 of the present embodiment, the power supply to the electric motor 48 of the variable lift mechanism 40 is stopped during the fuel cut operation, and the intake lift Liftin is predetermined by the lift holding mechanism 50. Since it is mechanically held at the value Liftin_ref, it is possible to reduce both the heat generation amount and the power consumption amount of the variable lift mechanism 40 during the fuel cut operation, as compared with the conventional case of controlling the variable lift mechanism.

  Further, the predetermined value Liftin_ref is set to a value that satisfies Liftin_min <Liftin_ref <Liftin_max. Therefore, compared to the case where the intake lift Liftin is held at the minimum value Liftin_min, the oil increase due to the negative pressure in the cylinder 3a is increased. And the rotational resistance acting on the crankshaft 3d of the engine 3 can be further increased. Thereby, when the vehicle is traveling at a reduced speed, a larger engine braking force can be ensured than when the intake lift Liftin is held at the minimum value Liftin_min.

  Further, during the fuel cut operation, the throttle valve opening TH is controlled so as to become the predetermined minimum opening THmin, so that it is sufficient when the engine 3 is in the fuel cut operation and the vehicle is decelerating. Engine braking force can be secured.

  The embodiment is an example using a lift holding mechanism that holds the intake lift Liftin at a predetermined value Liftin_ref when power supply to the electric motor 48 is stopped. The mechanism is not limited to this, and any mechanism that can mechanically hold the intake lift at a predetermined value when power supply to the electric motor of the variable lift mechanism is stopped. For example, in the lift holding mechanism 50 described above, a fluid spring such as an air spring or an elastic body such as rubber may be used instead of the coil springs 52 and 53.

  Further, instead of the lift holding mechanism 50 described above, a lift holding mechanism 50A shown in FIG. 13 may be used. In the following description, the same components as those of the lift holding mechanism 50 are denoted by the same reference numerals and the description thereof is omitted. As shown in FIG. 13, in the case of this lift holding mechanism 50A, when the power supply to the electric motor 48 of the variable lift mechanism 40 is stopped, the urging force of the two coil springs 52 and 53 causes the link 44a to move. It is configured to be held at the maximum lift position. Therefore, when the lift holding mechanism 50A is used, the power supply to the variable lift mechanism 40 can be stopped during the high load operation of the engine 3. As a result, during high load operation, both the amount of heat generated and the amount of power consumed by the variable lift mechanism 40 can be reduced, and the variable lift mechanism 40 can be prevented from becoming a load on the engine 3. Can be improved. When this lift holding mechanism 50A is used, a sufficient engine braking force may be ensured by controlling the throttle valve mechanism 13 during the fuel cut operation.

  Further, the embodiment is an example in which the variable lift mechanism 40 is used to continuously change the intake lift Liftin within a predetermined range. However, the variable lift mechanism of the present invention is not limited to this, and the electric motor As a power source, and the intake lift may be changed continuously within a predetermined range. For example, a variable lift mechanism that has been proposed by the present applicant in Japanese Patent Application Laid-Open No. 2007-224777 may be used.

  The embodiment is an example in which the throttle valve 13a is used as the intake passage valve. However, the intake passage valve of the present invention is not limited to this and may be an electric type that opens and closes the intake passage.

  The present invention can be applied to a control device that controls an internal combustion engine including a variable lift mechanism and a lift holding mechanism, and is also applied to a control device that controls, for example, a ship internal combustion engine or a power generation internal combustion engine. Can do.

1 control device 2 ECU (determination means, control means)
3 Internal combustion engine 4 Intake valve 12 Intake passage 13a Throttle valve (intake passage valve)
40 variable lift mechanism 48 electric motor 50 lift holding mechanism 50A lift holding mechanism Liftin intake lift Liftin_max predetermined maximum value Liftin_min predetermined minimum value Liftin_ref predetermined value
TH Throttle valve opening (opening of intake passage valve)
THmin Predetermined minimum opening

Claims (4)

The intake lift, which is the maximum lift during opening of the intake valve, can be continuously changed within a predetermined range defined by a predetermined maximum value and a predetermined minimum value by a variable lift mechanism using an electric motor as a power source. And a control device for an internal combustion engine, wherein the intake lift is mechanically held at a predetermined value within the predetermined range by a lift holding mechanism when power supply to the electric motor is stopped. There,
Determining means for determining whether or not the fuel cut operation for stopping the supply of fuel to the internal combustion engine is in progress;
Control means for stopping power supply to the electric motor when the fuel cut operation is being performed based on the determination result of the determination means;
A control device for an internal combustion engine, comprising:   The control apparatus for an internal combustion engine according to claim 1, wherein the predetermined value is a value within the predetermined range excluding the predetermined maximum value and the predetermined minimum value.   The control apparatus for an internal combustion engine according to claim 1, wherein the predetermined value is the predetermined maximum value. The internal combustion engine is mounted on a vehicle as a power source and includes an electric intake passage valve that opens and closes an intake passage.
When the internal combustion engine is in the fuel cut operation, the control means sets the intake passage valve so that the opening amount of the intake passage valve becomes a predetermined minimum opening amount in addition to stopping electric power to the electric motor. 4. The control device for an internal combustion engine according to claim 1, wherein the control device is controlled.

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