JP2006170033A - Control device of variable valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device avoiding operation failure of a variable valve mechanism caused by freezing. <P>SOLUTION: Formation of a freezing condition at a moving part of the variable valve mechanism is judged based on water temperature and oil temperature of an engine and on outside air temperature. On the formation of the freezing condition, a control objective value or a control signal of the variable valve mechanism is forcibly pulsated so that ice on the moving part of the variable valve mechanism is broken and separated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a variable valve mechanism that changes operating characteristics of an engine valve.

Patent Document 1 discloses a technical means that includes a variable valve mechanism that changes the valve opening amount of an intake valve and improves the engine startability by increasing the valve opening amount of the intake valve when the engine is started.
Japanese Patent Laid-Open No. 2004-092220

  By the way, in the variable valve mechanism, the combustion gas blown out from the piston ring enters the cylinder head from the crankcase, moisture contained in the combustion gas adheres to the movable part of the variable valve mechanism, and freezes while the engine is stopped. There is a possibility that.

  The ice generated in the movable part melts when the engine is restarted and the temperature of the cylinder head rises. However, as described above, if it is necessary to change the opening characteristics of the intake valve from the start, There is a possibility that the variable valve mechanism cannot be operated due to the biting of the water or the fixation by the ice.

  If the variable valve mechanism cannot be operated at the time of starting, the opening characteristic of the engine valve cannot be changed to a desired opening characteristic, and there arises a problem that startability deteriorates.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for a variable valve mechanism that can avoid the occurrence of malfunction of the variable valve mechanism due to freezing.

  Therefore, the invention according to claim 1 is configured to determine the icing condition of the variable valve mechanism and forcibly drive the variable valve mechanism when the icing condition is satisfied.

  According to this configuration, the condition for freezing of the movable part of the variable valve mechanism is determined, and when the freezing condition can occur, the variable valve mechanism is forcibly driven to bite the ice of the movable part. Alternatively, it is peeled off so that it can operate normally.

  Therefore, it is possible to avoid the occurrence of a malfunction in the variable valve mechanism due to a low temperature condition, the engine valve opening characteristic cannot be changed to a desired characteristic, and a starting failure or the like.

  The invention according to claim 2 is configured to determine at least one of the engine coolant temperature, the engine lubricating oil temperature, and the outside air temperature as the icing condition.

  According to such a configuration, a low temperature condition in which icing occurs in the cylinder head is determined from at least one of the engine coolant temperature, the engine lubricating oil temperature, and the outside air temperature. If so, the variable valve mechanism is forcibly driven.

  Therefore, it is possible to forcibly drive the variable valve mechanism by accurately determining the icing conditions in the variable valve mechanism.

  The invention according to claim 3 is configured to forcibly drive the variable valve mechanism by forcibly oscillating the target value or control signal of the variable valve mechanism.

  According to this configuration, the torque applied to the movable part is periodically changed by forcibly oscillating the target value of the variable valve mechanism (engine valve opening characteristic) or the control signal of the variable valve mechanism (actuator). Let the ice break up and peel off.

  Therefore, it is possible to effectively eliminate the icing state by forced driving of the variable valve mechanism.

  Embodiments of the present invention will be described below.

  FIG. 1 shows a variable valve mechanism and a control apparatus thereof according to an embodiment.

  In an engine to which the variable valve mechanism of the embodiment is applied, a pair of intake valves 2 are provided in each cylinder, and an intake drive shaft 3 that is rotationally driven by a crankshaft (not shown) above the intake valves 2. Is supported rotatably along the cylinder row direction.

  A swing cam 4 that contacts the valve lifter 2a of the intake valve 2 and opens and closes the intake valve 2 is externally fitted to the intake drive shaft 3 so as to be relatively rotatable.

  Between the intake drive shaft 3 and the swing cam 4, there is provided an operating angle changing mechanism 10 for continuously changing the operating angle and valve lift amount of the intake valve 2.

  A phase change mechanism 20 that continuously changes the center phase of the operating angle of the intake valve 2 by changing the rotational phase of the intake drive shaft 3 with respect to the crankshaft is provided at one end of the intake drive shaft 3. It is arranged.

  As shown in FIGS. 1 and 2, the operating angle changing mechanism 10 includes a circular drive cam 11 that is fixedly provided eccentric to the intake drive shaft 3, and a ring that is externally fitted to the drive cam 11 so as to be relatively rotatable. , A control shaft 13 extending in the cylinder row direction substantially parallel to the intake drive shaft 3, a circular control cam 14 which is fixedly provided eccentric to the control shaft 13, and a relative rotation with respect to the control cam 14 The rocker arm 15 has a rocker arm 15 that is externally fitted and connected at one end to the tip of the ring-shaped link 12, and a rod-shaped link 16 that is connected to the other end of the rocker arm 15 and the swing cam 4. .

  The control shaft 13 is rotationally driven within a predetermined control range via a gear train 18 by an electric actuator 17 (motor).

  With the above configuration, when the intake drive shaft 3 rotates in conjunction with the crankshaft, 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 via the rod-shaped link 16 and the intake valve 2 is driven to open and close.

  Further, by changing the rotation angle of the control shaft 13, the axial center position of the control cam 14 that becomes the swing center of the rocker arm 15 is changed, and the posture of the swing cam 4 is changed.

  As a result, the operating angle of the intake valve 2 and the valve lift amount continuously change while the central phase of the operating angle of the intake valve 2 remains substantially constant.

  FIG. 3 shows the phase changing mechanism 20.

  The phase changing mechanism 20 is fixed to a sprocket 25 that rotates in synchronization with the crankshaft, and is fixed to one end of the intake drive shaft 3 by a first rotating body 21 that rotates integrally with the sprocket 25 and a bolt 22a. A second rotating body 22 that rotates integrally with the intake drive shaft 3, and a cylindrical intermediate gear 23 that meshes with the inner peripheral surface of the first rotating body 21 and the outer peripheral surface of the second rotating body 22 by a helical spline 26; ,have.

  A drum 27 is connected to the intermediate gear 23 via a triple screw 28, and a torsion spring 29 is interposed between the drum 27 and the intermediate gear 23.

  The intermediate gear 23 is urged in the retarding direction (left direction in FIG. 3) by a torsion spring 29. When a voltage is applied to the electromagnetic retarder 24 to generate a magnetic force, the intermediate gear 23 passes through the drum 27 and the triple thread screw 28. Then, it is moved in the advance direction (right direction in FIG. 3).

  Depending on the position of the intermediate gear 23 in the axial direction, the relative phase of the rotating bodies 21 and 22 changes, and the phase of the intake drive shaft 3 with respect to the crankshaft changes.

  The electric actuator 17 and the electromagnetic retarder 24 are driven and controlled according to the operating state of the engine by a control signal from an engine control unit (ECU) 30.

  Detection signals from various sensors are input to the engine control unit 30 including a microcomputer.

  The various sensors include angle sensors 31 and 32 for detecting the angles of the intake drive shaft 3 and the control shaft 13, a crank angle sensor 33 for detecting the angle of the crankshaft, and an air flow meter 34 for detecting the intake air flow rate of the engine. A water temperature sensor 35 for detecting the coolant temperature Tw of the engine, an oil temperature sensor 36 for detecting the temperature of the lubricating oil of the engine, an outside air temperature sensor 37 for detecting the outside air temperature, and the like are provided.

  The engine control unit 30 controls the fuel injection amount, fuel injection timing, and ignition timing based on detection signals from the various sensors, and controls the operating angle and center phase of the intake valve 2.

  Furthermore, in the present embodiment, the engine control unit 30 performs control for eliminating the icing state occurring in the movable part of the operating angle changing mechanism 10 (variable valve mechanism) as shown in the flowchart of FIG. Do.

  In the flowchart of FIG. 4, in step S <b> 1, it is determined whether a drive permission condition for the operating angle changing mechanism 10 is satisfied.

  As the drive permission condition, failure of the operating angle changing mechanism 10 is not diagnosed, the engine is rotating (including cranking), and the voltage of the battery as a power source is equal to or higher than a predetermined value. Etc. are included.

  If it is determined in step S1 that the drive permission condition is not satisfied, the process proceeds to step S2, and the driving of the operating angle changing mechanism 10 (power supply to the electric actuator 17) is prohibited.

  On the other hand, if it is determined in step S1 that the drive permission condition is satisfied, the process proceeds to step S3.

  In step S3, it is determined whether or not the icing condition in the operating angle changing mechanism 10 is satisfied.

  The icing condition refers to a temperature condition in which moisture adhering to the gear train 18 (movable part) that transmits the driving force of the electric actuator 17 to the control shaft 13 is frozen in the operating angle changing mechanism 10.

  Moisture-containing combustion gas blows off from the piston ring into the crankcase and enters the cylinder head. After that, when the engine is stopped in an environment where the outside air temperature is low, the condensed moisture may freeze on the gear train 18 and the like. .

  As described above, when the gear example 18 freezes, the opening / closing characteristics (operating angle, lift amount) of the intake valve 2 are characteristics required for starting (cranking) from characteristics (default position) when the engine is stopped. The startability is deteriorated because the change cannot be made up to.

  Therefore, in step S3, it is determined from the water temperature Tw, the oil temperature, and the outside air temperature whether or not the operating angle changing mechanism 10 is in a condition where icing (freezing of the gear train 18) occurs.

  Specifically, if the water temperature Tw and / or the oil temperature is about 0 ° C. or less, it is determined that the icing condition is satisfied, and further, at the time of start and the outside air temperature at that time is about 0 ° C. or less. In some cases, it is determined that the icing condition is satisfied.

  Further, it can be determined that the icing condition is satisfied at the start-up when the engine is stopped for a predetermined time or more and the outside air temperature is about 0 ° C. or less.

  Furthermore, the temperature of the cylinder head or the electric actuator 17 can be directly detected by a sensor, and it can be determined whether or not the detected temperature is near 0 ° C. or less.

  If it is determined in step S3 that the icing condition is not satisfied, the process proceeds to step S4, and the operating angle changing mechanism 10 is normally controlled (normal drive mode is executed).

  In the normal control, the target opening characteristic (target operating angle or target lift amount) of the intake valve 2 is set from the engine operating state (rotation speed, load, water temperature, etc.), and the angle corresponding to the target opening characteristic is set to the angle. A control signal (duty signal) output to the electric actuator 17 is feedback-controlled based on the detection result of the angle sensor 32 so that the angles of the control shafts 13 coincide.

  The engine rotation speed is calculated based on a detection signal from the crank angle sensor 33, and the engine load is calculated based on the cylinder intake air amount (basic) based on the intake air flow rate detected by the air flow meter 34 and the engine rotation speed. (Fuel injection amount).

  On the other hand, when it is determined in step S3 that the icing condition is satisfied, the process proceeds to step S5, whether or not a predetermined time (for example, 100 ms) has elapsed since the icing condition is satisfied, in other words, the icing state is changed. It is determined whether or not the control to be canceled is continuously performed for the predetermined time or more.

  If it is determined in step S5 that a predetermined time (for example, 100 ms) has not elapsed since the establishment of the icing condition, the process proceeds to step S6 to execute control for eliminating the icing state (executes the icing drive mode). ).

  However, if icing elimination control (described later) is performed in normal engine operating conditions other than during start-up (cranking), engine operability such as exhaust gas performance and fuel consumption performance will be reduced. Is limited to a short time during cranking or fuel cut.

  On the other hand, when it is determined in step S5 that a predetermined time (for example, 100 ms) has elapsed since the establishment of the icing condition, the process proceeds to step S4 to normally control the operating angle changing mechanism 10 (normal drive mode). Run).

  That is, the icing elimination control is executed only for the predetermined time (for example, 100 ms) to avoid the influence on the drivability and the increase in power consumption due to excessive icing elimination control.

The freezing elimination control in step S6 performs any of the following controls.
(1) The control target value of the operating angle changing mechanism 10 is vibrated smoothly at a constant period around the original control target value.
(2) The control signal of the operating angle changing mechanism 10 is forcibly vibrated stepwise at a constant period.

  When the control signal of the operating angle changing mechanism 10 is forcibly vibrated stepwise at a constant period, the control signal is switched so that the direction of torque applied to the control shaft 13 (rotational drive direction) is periodically switched. The control signal may be vibrated so that the torque applied in the same rotational direction fluctuates.

  By oscillating the control target value or the control signal as described above, the torque generated by the actuator 17 fluctuates, and the ice frozen on the gear train 18 and the like is peeled and crushed to return to a normal operational state. Plan.

  Therefore, for example, even in a situation where the operating angle changing mechanism 10 does not normally operate due to icing while the engine is stopped, the intake valve required at the time of starting is made ready for normal operation by the icing elimination control immediately after the start of starting. 2 open characteristics (operating angle, lift amount).

  Thereby, it is possible to avoid deterioration of startability due to freezing while the engine is stopped.

  In the above-described embodiment, the operating angle changing mechanism 10 shown in FIG. 1 is determined to determine the conditions under which freezing occurs in the movable part. When the conditions are such that freezing can occur, the operating angle changing mechanism 10 is forcibly driven. By adopting appropriately for all known variable valve mechanisms that change the opening characteristics of the engine valve by the phase changing mechanism 20 or other mechanisms, the same actions and effects as in the above embodiment can be obtained.

  The other mechanism includes a variable valve mechanism that directly opens and closes the engine valve by electromagnetic or hydraulic pressure without using the camshaft (intake drive shaft 3) that is linked to the crankshaft.

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 any one of claims 1 to 3, the time for forcibly driving the variable valve mechanism is limited within a predetermined time. Control device for variable valve mechanism.

  According to this configuration, even if the icing condition is satisfied, if the variable valve mechanism is forcibly driven for a predetermined time, the forcible drive is stopped and returned to normal drive control.

Therefore, it is possible to suppress the influence on the operability and the like by forcibly driving the variable valve mechanism to the minimum necessary.
(B) In the control apparatus for a variable valve mechanism according to claim 2,
A control apparatus for a variable valve mechanism, wherein it is determined that an icing condition is satisfied when an outside air temperature at the time of starting the engine is equal to or lower than a predetermined temperature.

  According to such a configuration, the possibility of icing while the engine is stopped is determined from the outside air temperature at the start, and it is determined whether or not the variable valve mechanism is to be forcibly driven.

  Therefore, the possibility of freezing while the engine is stopped can be determined from the outside air temperature.

The perspective view which shows the variable valve mechanism and its control apparatus in embodiment. Sectional drawing of the operating angle change mechanism shown in FIG. Sectional drawing which shows the phase change mechanism shown in FIG. The flowchart which shows the icing elimination control in embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Intake valve, 3 ... Intake drive shaft, 4 ... Swing cam, 10 ... Operating angle change mechanism, 11 ... Drive cam, 12 ... Ring link, 13 ... Control shaft, 14 ... Control cam, 15 ... Rocker arm, 16 DESCRIPTION OF SYMBOLS ... Rod-shaped link, 17 ... Electric actuator, 18 ... Gear train, 20 ... Phase change mechanism, 30 ... Engine control unit, 31, 32 ... Angle sensor, 33 ... Crank angle sensor, 34 ... Air flow meter, 35 ... Water temperature sensor, 36 ... Oil temperature sensor, 37 ... Outside temperature sensor

Claims (3)

A control device for a variable valve mechanism that changes the operating characteristics of an engine valve,
A control apparatus for a variable valve mechanism, which determines an icing condition of the variable valve mechanism and forcibly drives the variable valve mechanism when the icing condition is satisfied.   2. The control device for a variable valve mechanism according to claim 1, wherein at least one of engine cooling water temperature, engine lubricating oil temperature, and outside air temperature is determined as the icing condition.   3. The control apparatus for a variable valve mechanism according to claim 1, wherein the variable valve mechanism is forcibly driven by forcibly oscillating a target value or a control signal of the variable valve mechanism. .

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