JP2009299585A - Control device for variable valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a variable valve train capable of suitably driving the variable valve train of a control device of a hydraulic actuator having a dead zone. <P>SOLUTION: The control device for the variable valve train is provided with a variable valve train (20, etc.) capable of varying valve characteristics of an internal combustion engine, a driving means (10, etc.) for driving the variable valve train by lubricating oil of the internal combustion engine, a specifying means (40, etc.) for specifying the dead zone wherein there is no responsiveness that valve characteristics are varied in accordance with variation of a driving amount of the driving means or the responsiveness is lower than the prescribed value, and a control means (40, etc.) for controlling the driving means to drive the variable valve train in accordance with the range of the specified dead zone when the dead zone is specified and controlling the driving means to drive the variable valve train at the prescribed driving amount when the dead zone is not specified. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a variable valve mechanism (so-called variable valve timing (VVT)) that variably controls the opening / closing timing of an intake valve or an exhaust valve in an internal combustion engine, such as a control device for a hydraulic actuator, for example. Related to the technical field.

  As a control device for this type of variable valve mechanism, a control device is disclosed that performs duty control with a predetermined amplitude in the dead zone region of the variable valve mechanism and learns the dead zone by gradually increasing or decreasing the amplitude. (See Patent Document 1).

  Alternatively, as a control device for this type of variable valve mechanism, in the control of the variable valve mechanism, the maximum deviation value is learned by detecting the valve characteristic deviation for each temperature range of the hydraulic oil, and the duty ratio is changed. A control device is disclosed (see Patent Document 2).

  Alternatively, as a control device for this type of variable valve mechanism, there is also a technique for identifying the dead zone based on the response of the variable valve mechanism and setting the drive duty by distinguishing between the dead zone area and the outside of the dead zone area. Proposed.

JP 2003-336529 A JP 2004-92534 A

  However, according to Patent Document 1 and the like described above, when the dead zone cannot be specified in a learning manner, the variable valve mechanism may be driven by a drive amount that does not consider the dead zone range. For this reason, there is a possibility that the responsiveness in which the valve characteristic changes is significantly reduced. For this reason, for example, even when the target value of the valve characteristic changes according to the operating state of the internal combustion engine, there is a possibility that a state in which the deviation between the target value and the actual value of the valve characteristic is large continues for a long time. There is a technical problem. For this reason, there is a technical problem that the operating state of the internal combustion engine becomes unstable and there is a possibility that drivability such as engine stop or engine vibration may deteriorate.

  Therefore, the present invention has been made in view of the above-described problems, for example, and controls a variable valve mechanism that can appropriately drive a variable valve mechanism such as a control device for a hydraulic actuator having a dead zone. It is an object to provide an apparatus.

  In order to solve the above-described problems, a control apparatus for a variable valve mechanism according to the present invention includes a variable valve mechanism that can change a valve characteristic of an internal combustion engine, and the variable valve mechanism that is driven by lubricating oil of the internal combustion engine. And a specifying unit for specifying a dead zone in which the valve characteristic is not responsive to change in response to a change in the driving amount of the driving unit or the responsiveness is in a range of the driving amount that is lower than a predetermined value; When the dead zone is specified, the driving means is controlled to drive the variable valve mechanism according to the range of the specified dead zone. When the dead zone is not specified, the variable valve mechanism is set to a predetermined value. Control means for controlling the drive means so as to drive with a drive amount.

  According to the control apparatus for a variable valve mechanism according to the present invention, the valve characteristics of the internal combustion engine can be changed by the variable valve mechanism. Here, the valve characteristic according to the present invention means a property related to the operation of the valve such as the valve opening timing, the valve closing timing, the operating angle, or the lift amount in a valve such as an intake valve or an exhaust valve.

  The variable valve mechanism is driven by the lubricating oil of the internal combustion engine by the driving means. Typically, the drive means drives the variable valve mechanism by changing the supply route or discharge route of the lubricant supplied to the variable valve mechanism, or by stopping the flow of supply or discharge of the lubricant. be able to.

  By the specifying means, a dead zone is specified in which there is no responsiveness in which the valve characteristic changes in accordance with a change in the driving amount of the driving means or the responsiveness is in a driving amount range lower than a predetermined value. Here, “specific” according to the present invention typically “specifically” “estimates” the range of the dead zone directly or indirectly or from the range of some physical quantity or parameter indicating the dead zone. Means that. In addition to or in place of this, the “specific” according to the present invention refers to “detection”, “detection”, and “measurement” of the dead zone directly or indirectly from the range of some physical quantity or parameter indicating the dead zone. Means to equal. More typically, the amount of change in the valve characteristic or the time rate of change in the valve characteristic in accordance with the change in the drive amount of the drive means is determined by the individual difference of the drive means itself, the temperature inside or outside the drive means, the lubricating oil It may be specified quantitatively or qualitatively, theoretically, experimentally, empirically, or simulation, taking into account variations in various conditions and parameters such as the temperature of the engine, the engine speed of the internal combustion engine or the load. The predetermined value according to the present invention means a value that quantitatively indicates the level of responsiveness of the driving amount of the driving means to the valve characteristics that can change the operating state of the internal combustion engine. This predetermined value can be obtained individually and concretely by theoretical, experimental, empirical, simulation, or the like based on whether or not the operating state of the internal combustion engine can be changed.

  When the dead zone is specified under the control of the control means, the variable valve mechanism is driven by the drive means according to the specified dead zone range. Typically, the variable valve mechanism is driven by the drive means by adding the upper limit value or the lower limit value of the specified dead band range to the drive amount used outside the dead band range. As a result, even if the dead zone fluctuates due to variations in various conditions and parameters such as individual differences in the driving means and temperature inside or outside the driving means, it is appropriate for fluctuations in the dead zone due to these variations. In response to this, the driving means can be driven with high accuracy.

  On the other hand, when the dead zone is not specified, the variable valve mechanism is driven by a predetermined drive amount by the drive means under the control of the control means. Here, the predetermined drive amount according to the present invention is within the range of the dead zone without considering the individual differences of the drive means described above and the variations of various conditions and parameters such as the temperature inside or outside the drive means. This is a constant of the drive amount that can be used outside the range of the dead zone. This predetermined driving amount is theoretically, experimentally, and empirically so that the deviation between the target value of the valve characteristic and the actual value that is the actual value of the valve characteristic is small even when the dead zone is not specified. It can be specifically obtained by simulation or the like.

  As a result, the variable valve mechanism is more appropriately driven by the driving means in accordance with whether or not the dead zone has been specified as described above. Thereby, the influence of a dead zone can be reduced and the responsiveness of a valve characteristic can be improved. Thereby, for example, when the target value of the valve characteristic changes according to the operating state of the internal combustion engine, the actual value that is the actual value of the valve characteristic can be quickly and accurately followed by the changed target value. The operating state of the internal combustion engine can be stabilized. As a result, deterioration of drivability such as occurrence of engine stop and engine vibration can be effectively prevented.

  If the drive means drives the variable valve mechanism under the control of the control means without considering whether or not the dead band has been specified, the dead band range cannot be specified, so the dead band can be ignored or lowered. There is a possibility that the variable valve mechanism is driven by the estimated driving amount. For this reason, there is a possibility that the responsiveness in which the valve characteristic changes is significantly reduced. For this reason, for example, even when the target value of the valve characteristic changes according to the operating state of the internal combustion engine, there is a possibility that a state in which the deviation between the target value and the actual value of the valve characteristic is large continues for a long time. . For this reason, the operating state of the internal combustion engine becomes unstable, and there is a possibility that drivability such as occurrence of engine stop or engine vibration may deteriorate.

  In one aspect of the control apparatus for a variable valve mechanism according to the present invention, when the dead zone is not specified, the control unit changes, as the predetermined drive amount, a drive amount used within the dead zone to an increase side. The driving means is controlled so as to drive the variable valve mechanism with the first driving amount.

  According to this aspect, when the dead zone is not specified, the responsiveness of the valve characteristics can be reliably improved as compared with the case where the drive amount used within the dead zone is not changed.

  In another aspect of the control apparatus for a variable valve mechanism according to the present invention, the control means changes the valve characteristic to one of the advance side and the retard side when the dead zone is specified. And controlling the drive means to drive the variable valve mechanism with a second drive amount used outside the dead zone upper limit value and the dead zone range, and setting the valve characteristics to an advance side and a retard angle. The drive means is controlled to drive the variable valve mechanism with the lower end value of the dead zone and the second drive amount when changing to the other side.

  According to this aspect, it is possible to make the drive unit more accurate by appropriately responding to fluctuations in the dead zone due to individual conditions of the drive unit itself and variations in various conditions and parameters such as temperature inside or outside the drive unit. Can be driven.

  In another aspect of the control apparatus for a variable valve mechanism according to the present invention, deviation detecting means for detecting a deviation between the target value of the valve characteristic and an actual value that is an actual value of the valve characteristic, and the detected In addition to or in place of the deviation, there is further provided determination means for determining whether or not the dead zone has been specified according to a temporal change in the detected deviation.

  According to this aspect, whether or not the dead zone has been specified can be determined with high accuracy according to the temporal change of the detected deviation in addition to or instead of the deviation.

  In the aspect according to the determination means, the determination means includes first determination means for determining whether or not a deviation between the target value and the actual value is greater than a first threshold, and a temporal change amount of the deviation. May be configured to include second determination means for determining whether or not is smaller than a second threshold smaller than the first threshold.

  The first threshold value according to the present invention may typically mean a deviation that can change the operating state of the internal combustion engine. The first deviation can be obtained individually and concretely by theoretical, experimental, empirical, simulation, or the like based on whether or not the operating state of the internal combustion engine can be changed to some extent. The second threshold according to the present invention may typically mean a value smaller than the first threshold described above. If comprised in this way, it can be determined more accurately by comparing with a 1st threshold value and a 2nd threshold value whether the dead zone was specified.

  In another aspect of the control device for a variable valve mechanism according to the present invention, the drive means supplies the lubricating oil in addition to or instead of changing the lubricating oil supply path or the lubricating oil discharge path. Alternatively, it has an oil control valve that drives the variable valve mechanism by stopping discharging, and the control means sends a predetermined drive signal to the oil control valve to bring the valve characteristic closer to a target value of the valve characteristic. By outputting, the oil control valve is controlled so as to drive the variable valve mechanism.

  According to this aspect, the variable valve mechanism can be driven with high accuracy by the predetermined drive signal output to the oil control valve.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Basic configuration)
First, a configuration of a hydraulic system that is an example of a control device of a variable valve mechanism (so-called variable valve timing (VVT)) according to the present embodiment will be described with reference to FIGS. 1 and 2. . FIG. 1 is a block diagram illustrating a configuration of a hydraulic system that is an example of a control device for a variable valve mechanism according to the present embodiment. FIG. 2 is a schematic diagram (FIGS. 2A, 2B, and 2B) conceptually showing three types of operations in an oil control valve (OCV) constituting the hydraulic system according to the present embodiment. FIG. 2 (c)). FIG. 3 shows the amount of change in the position of the spool in the oil control valve according to this embodiment, and the change in the opening length between the ports that supply or discharge the lubricating oil to the advance side oil chamber or the retard side oil chamber. It is the graph which showed correlation with. The present embodiment can be applied to either the variable valve mechanism of the intake valve or the exhaust valve, but here, the present embodiment is applied to the variable valve mechanism of the intake valve.

  As shown in FIG. 1, the hydraulic system of the variable valve mechanism according to the present embodiment includes an oil control valve 10, a spool 12, a solenoid 14, a spring 16, a sleeve 18, a hydraulic actuator 20, a housing 22, a rotor 24, The advance angle side oil chamber 26, the retard angle side oil chamber 28, the oil pump 30, the oil tank 32, the control device 40, the crank angle sensor 42, the cam angle sensor 44, the oil temperature sensor 46, and the advance angle side oil chamber 26 are communicated. A port, a B port, a Ra port (so-called advance drain), and an Rb port (so-called retard drain) communicated with the A-port, retard-side oil chamber 28 are configured.

  The hydraulic actuator 20 changes the displacement angle of the cam shaft with respect to the crank shaft. The hydraulic actuator 20 includes a housing 22 that rotates in synchronization with the crankshaft, and a rotor 24 that is disposed in the housing 22 and rotates in synchronization with the camshaft. Oil chambers 26 and 28 are formed inside the housing 22. The oil chambers 26 and 28 are divided into an advance side oil chamber 26 and a retard side oil chamber 28 by the rotor 24.

  The hydraulic actuator 20 operates when pressurized oil (that is, lubricating oil) is supplied to the oil chambers 26 and 28 and the rotation angle of the rotor 24 with respect to the housing 22 changes. When pressurized oil is supplied to the advance side oil chamber 26, the hydraulic actuator 20 operates to change the displacement angle of the cam shaft relative to the crankshaft to the advance side, and the pressurized oil is supplied to the retard side oil chamber 28. When is supplied, the camshaft is operated so as to change the displacement angle of the camshaft relative to the crankshaft to the retard side. At this time, from the oil chamber on the side where the pressurized oil is not supplied, the internal pressurized oil is pushed out and discharged along with the expansion of the oil chamber on the side where the pressurized oil is supplied. The detailed flow of pressurized oil will be described later.

  The pressurized oil supplied to the hydraulic actuator 20 is pumped from an oil pump 30 driven by the engine. An oil control valve (hereinafter referred to as “OCV” as appropriate) 10 is provided between the oil pump 30 and the hydraulic actuator 20. The oil control valve 10 constitutes an example of drive means according to the present invention. Moreover, the hydraulic actuator 20 constitutes an example of variable valve operating means according to the present invention. The OCV 10 is a 5-port spool valve, and supplies and discharges pressurized oil to and from the oil chamber 26 and the oil chamber 28 of the hydraulic actuator 20 depending on the position of the spool 12 in the sleeve 18 (hereinafter referred to as “supply / discharge” as appropriate). Can be controlled. The A port of the OCV 10 is connected to the advance side oil chamber 26 of the hydraulic actuator 20, and the B port is connected to the retard side oil chamber 28. Further, the P port of the OCV 10 is connected to the oil pump 30, and the Ra port (so-called advance drain) and the Rb port (so-called retard drain) are connected to the oil tank 32.

  The control device 40 performs duty control of the OCV 10 by feedback control based on the deviation between the actual displacement angle of the hydraulic actuator 20 and the target displacement angle.

  The spool 12 is supported by a spring 16 at one end in the moving direction and supported by a solenoid 14 at the other end. The position of the spool 12 within the sleeve 18 can be controlled by the duty of the drive current supplied to the solenoid 14 (hereinafter referred to as OCV drive duty). The OCV drive duty constitutes an example of the drive amount according to the present invention. As shown in FIG. 2B, at the position of the spool 12, the communication between the A port and the B port and the P port, the Ra port, and the Rb port is blocked, and the oil chamber 26 and the oil chamber 28 are added. There is virtually no pressure oil supply or discharge. Hereinafter, the operation range of the spool 12 in which the communication between the A port and the B port and the P port, the Ra port, and the Rb port is blocked is referred to as a neutral region. Specifically, as shown in FIG. 3, the supply stop section, which is the position range of the spool 12 where the supply of pressurized oil through the P port stops, is the pressurized oil through the Ra port or Rb port. It may be set to be smaller than the discharge stop section which is the position range of the spool 12 where the discharge of the spool 12 stops. In particular, due to the supply stop section and the discharge stop section, a neutral zone and a dead zone described later are formed.

  When the OCV drive duty is reduced in a state where the spool 12 is in the neutral range, as shown in FIG. 2A, the spool 12 is pushed by the spring 16 and moves rightward in FIG. As a result, the A port communicates with the P port, the B port communicates with the Rb port, the supply of pressurized oil to the advance side oil chamber 26, and the discharge of pressurized oil from the retard side oil chamber 28. Will be performed at the same time. Hereinafter, the operating range of the spool 12 in which pressurized oil is supplied to the advance side oil chamber 26 is referred to as an advance angle range. Specifically, as shown in FIG. 3, the opening length when the B port communicating with the retarded-side oil chamber 28 and the Rb port communicating with the oil tank 32 are in the open state is the spool 12 Decreases as it moves to the right. In addition, the opening length when the A port communicating with the advance side oil chamber 26 and the P port capable of supplying pressurized oil are in an open state decreases as the spool 12 moves to the right. To do. Particularly, the maximum value of the opening length when the A port and the P port are in the open state is larger than the maximum value of the opening length of the B port and the Rb port.

  On the other hand, if the OCV drive duty increases while the spool 12 is in the neutral range, the spool 12 is pushed by the solenoid 14 and moved to the left in FIG. 2C, as shown in FIG. To do. As a result, the A port communicates with the Ra port, the B port communicates with the P port, supply of pressurized oil to the retard side oil chamber 28, and discharge of pressurized oil from the advance side oil chamber 26. Will be performed at the same time. Hereinafter, the operation range of the spool 12 in which the pressurized oil is supplied to the retard side oil chamber 28 is referred to as a retard range. Specifically, as shown in FIG. 3, the opening length when the B port communicating with the retarded-side oil chamber 28 and the P port capable of supplying pressurized oil are in an open state is set to the spool Increases as 12 moves to the right. In addition, the opening length when the A port communicating with the advance side oil chamber 26 and the Ra port communicating with the oil tank 32 are in the open state increases as the spool 12 moves to the right. . In particular, the maximum value of the opening length when the B port and the P port are in the open state is larger than the maximum value of the opening length of the A port and the Ra port. Needless to say, the direction in which the OCV drive duty increases or decreases as described above and the control method toward the advance angle region or the control method toward the retard angle region can be freely combined as appropriate. .

(Correlation between OCV drive duty and displacement speed of hydraulic actuator that drives variable valve mechanism)
Next, the correlation between the OCV drive duty and the displacement speed of the hydraulic actuator that drives the variable valve mechanism in the hydraulic system of the variable valve mechanism according to the present embodiment will be described with reference to FIG. FIG. 4 is a characteristic diagram showing the correlation between the OCV drive duty and the displacement speed of the hydraulic actuator in the hydraulic system of the variable valve mechanism according to the present embodiment. The displacement speed of the hydraulic actuator that drives the variable valve mechanism means the change speed of the displacement angle of the camshaft relative to the crankshaft. Further, the OCV drive duty Dt in FIG. 4 indicates the value of the OCV drive duty when the displacement speed (CA / sec: Crank Angle per second) is zero.

  As shown in FIG. 4, in the variable valve mechanism according to the present embodiment, the change in the duty value is in the vicinity of the duty at which the displacement speed of the hydraulic actuator 20 is maintained at zero (hereinafter referred to as “holding duty”). There is a dead zone in which the change in the displacement speed is small, that is, the response to the change in the duty value is lower than a predetermined value. Here, the predetermined value according to the present embodiment means a value that quantitatively indicates the level of responsiveness of the drive amount of the drive means to the valve characteristics, which can change the operation state of the internal combustion engine. This predetermined value can be obtained individually and concretely by theoretical, experimental, empirical, simulation, or the like based on whether or not the operating state of the internal combustion engine can be changed.

  In particular, the neutral region in the operation region of the spool 12 is formed with a certain width. The range of the OCV drive duty when the spool 12 is in the neutral range becomes a dead zone. The dead zone of the OCV 10 may be specified by learning while controlling the operation of the hydraulic actuator 20 by duty control of the OCV 10. However, in carrying out the present invention, there is no limitation on the dead zone learning method, and any of the conventionally proposed methods may be used. As an example, the absolute value of the displacement speed of the hydraulic actuator 20 is calculated, and the previous value is larger than a predetermined reference value. When the current value is larger than the predetermined reference value, the OCV drive duty at that time is calculated. A learning method that specifies the upper limit value or the lower limit value of the dead zone may be used. As another example of the learning method, a learning method is performed in which the maximum value of the OCV drive duty in a range where the absolute value of the displacement speed of the hydraulic actuator 20 is equal to or less than a predetermined reference value is specified as the upper limit value of the dead zone. A learning method may be performed in which the minimum value of the OCV drive duty at 1 is specified as the lower limit value of the dead zone.

  When the OCV drive duty is decreased beyond the dead zone, the displacement speed of the hydraulic actuator 20 starts to increase toward the advance side, and changes linearly with respect to the change in the OCV drive duty. This is because the operating range of the spool 12 has shifted from the neutral range to the advance angle range. When the OCV drive duty is reduced to a certain level, the displacement speed of the hydraulic actuator 20 reaches the maximum advance speed, and the displacement speed is kept constant even if the OCV drive duty is further increased. At this time, the spool 12 moves to the limit position of the advance angle region, and the A port communicating with the advance angle side oil chamber 26 and the P port capable of supplying pressurized oil are completely in communication. In addition to this, the B port communicating with the retarded-side oil chamber 28 and the Rb port communicating with the oil tank 32 are in a completely communicating state.

  On the other hand, when the OCV drive duty is increased beyond the dead zone, the displacement speed of the hydraulic actuator 20 starts to increase toward the retard side and changes linearly with respect to the change in the OCV drive duty. This is because the operating range of the spool 12 has shifted from the neutral range to the retarded range. When the OCV drive duty increases to a certain extent, the displacement speed of the hydraulic actuator 20 reaches the maximum retarding speed, and the displacement speed is kept constant even if the OCV drive duty is further decreased. At this time, the spool 12 has moved to the limit position of the retarded angle region, and the A port communicating with the advanced angle side oil chamber 26 and the Ra port communicating with the oil tank 32 are in a completely communicating state. In addition to this, the B port communicating with the retard side oil chamber 28 and the P port capable of supplying pressurized oil are completely in communication.

  The control of the OCV 10 is performed by the control device 40. The control device 40 and a mechanism portion including the hydraulic actuator 20 and the OCV 10 (that is, a variable valve mechanism) constitutes a valve timing variable device. The control device 40 sets a target displacement angle of the camshaft with respect to the crankshaft, and calculates an OCV drive duty based on a deviation between the actual displacement angle and the target displacement angle. The control device 40 outputs the calculated OCV drive duty to the OCV 10 as a control signal. An example of the “actual value” according to the present invention is configured by the actual displacement angle, and an example of the “target value” according to the present invention is configured by the target displacement angle. Further, the target displacement angle is determined from a map using the operating state of the engine as a parameter. The actual displacement angle can be calculated from the output signal of the crank angle sensor 42 and the output signal of the cam angle sensor 44. In addition, the control device 40 can acquire the output signal of the oil temperature sensor 46 that measures the temperature of the pressurized oil, and the actual displacement angle is calculated from the acquired output signal of the oil temperature sensor 46. Good. The control device 40 constitutes an example of “control means” or “specification means” according to the present invention.

(Operating principle)
Next, the principle of operation of the hydraulic system for the variable valve mechanism according to the present embodiment will be described with reference to FIGS. FIG. 5 is a flowchart showing the flow of control processing of the hydraulic system that is an example of the control device for the variable valve mechanism according to the present embodiment. This control process is repeatedly executed by the control device 40 at a predetermined cycle such as several tens of microseconds or several microseconds. FIG. 6 is a graph showing changes with time of the displacement angle of the variable valve mechanism according to the present embodiment.

  As shown in FIG. 5, first, it is determined whether or not the target displacement angle of the variable valve mechanism has changed under the control of the control device 40 (step S101). Specifically, as indicated by the dotted line in FIG. 6, it is determined whether or not the target displacement angle has changed discontinuously. Here, when it is determined that the target displacement angle has changed (step S101: Yes), it is further determined whether or not the target displacement angle has become stable under the control of the control device 40 (step S102). Here, when it is determined that the target displacement angle is stable (step S102: Yes), the deviation between the target displacement angle and the actual displacement angle is larger than the first threshold value under the control of the control device 40. It is determined whether or not (step S103). Here, the first threshold value according to the present embodiment may typically mean a deviation that can change the operating state of the internal combustion engine. The first deviation can be obtained individually and concretely by theoretical, experimental, empirical, simulation, or the like based on whether or not the operating state of the internal combustion engine can be changed to some extent. Specifically, it is determined whether or not the deviation from the actual displacement angle is larger than the first threshold shown in FIG. Here, when it is determined that the deviation between the target displacement angle and the actual displacement angle is larger than the first threshold (step S103: Yes), the target displacement angle has changed under the control of the control device 40. Thereafter, it is determined whether or not a predetermined time has passed (step S104). Here, the predetermined time according to the present embodiment may typically mean a time during which the operating state of the internal combustion engine can be changed by a change in the target displacement angle. Specifically, it is determined whether or not a predetermined time shown in FIG. 6 has elapsed after the target displacement angle has changed. As a result of the determination in step S104, when it is determined that a predetermined time has elapsed after the target displacement angle has changed (step S104: Yes), the target displacement angle and the actual displacement are further controlled under the control of the control device 40. It is determined whether or not the absolute value of the deviation from the displacement angle is smaller than the second threshold value (step S105). Here, the second threshold value according to the present embodiment may typically mean a value smaller than the first threshold value described above. Specifically, it is determined whether or not the absolute value of the deviation between the target displacement angle and the actual displacement angle is smaller than a second threshold value shown in FIG. As a result of the determination in step S105, when it is determined that the absolute value of the deviation between the target displacement angle and the actual displacement angle is smaller than the second threshold (step S105: Yes), the control device 40 sets the dead zone range. It is determined that the learning process specified by learning is completed (step S106). Subsequently, under the control of the control device 40, the OCV is driven with the OCV driving duty when the learning process is completed (step S107). Typically, under the control of the control device 40, an OCV drive duty drive instruction signal in which the upper end value or the lower end value of the dead zone range in which the learning process is completed is added to the OCV drive duty used outside the dead zone range. The variable valve mechanism is driven by being input to the OCV. As a result, even if the dead zone fluctuates due to variations in individual conditions of OCV itself and variations in various conditions and parameters such as the temperature inside or outside the OCV, it appropriately handles the fluctuation of the dead zone due to these variations. Thus, the OCV can be driven with high accuracy.

  On the other hand, if it is not determined that the absolute value of the deviation between the target displacement angle and the actual displacement angle is smaller than the second threshold as a result of the determination in step S105 described above (step S105: No), It is determined that the learning process for learning the range is not completed (step S108). Subsequently, under the control of the control device 40, the OCV is driven with the OCV driving duty when the learning process is not completed (step S109). The OCV drive duty when the learning process is not completed is typically within the dead zone without considering individual conditions of the OCV itself and variations in various conditions and parameters such as temperature inside or outside the OCV. In addition, it means a predetermined OCV drive duty that can be used outside the dead zone. This predetermined OCV drive duty is calculated theoretically, experimentally, empirically, or simulation so that the deviation between the target displacement angle and the actual displacement angle is small even when the dead zone learning process is not completed. Can be obtained individually and specifically.

(Examination of actions and effects according to this embodiment)
Next, the action and effect of the hydraulic system for the variable valve mechanism according to the present embodiment will be discussed with reference to FIG. FIG. 7 is a characteristic diagram showing the correlation between the OCV drive duty and the displacement speed of the hydraulic actuator that drives the variable valve mechanism in the hydraulic system of the variable valve mechanism according to this embodiment and the comparative example. is there.

  As described above, according to the present embodiment, when the learning process for specifying the dead zone range in a learning manner is completed, the variable valve mechanism is driven according to the specified dead zone range. Typically, under the control of the control device 40, the OCV drive duty amount (see “α” in FIG. 7) used by the OCV outside the dead band range is set to the upper limit value (see “α” in FIG. 7). A value obtained by adding the OCV drive duty amount “β” in the dead zone at the completion of learning in FIG. 7 or “a” in FIG. 7) (see the OCV drive duty “c” at the completion of learning in FIG. 7). ) Drives the variable valve mechanism. Thereby, it is possible to improve the responsiveness in which the displacement angle of the variable valve mechanism changes. Specifically, the displacement speed Va at the completion of learning corresponding to the OCV drive duty “c” at the completion of learning in FIG. 7 is associated with the OCV drive duty “d” at the time of completion of learning in FIG. The displacement speed Vx at the completion of learning can be made larger. Furthermore, even if the dead zone fluctuates due to variations in various conditions and parameters such as individual differences in the OCV itself and temperatures inside or outside the OCV, it is suitable for fluctuations in the dead zone due to these variations. In response to this, the OCV can be driven with high accuracy.

  On the other hand, when the learning process for learning the dead zone range is not completed, under the control of the control device 40, the variable valve mechanism is controlled by the OCV so that the OCV itself has individual differences, the temperature inside or outside the OCV, and the like. Without considering the various conditions and parameters, the driving is performed with a predetermined OCV driving duty that can be used outside the dead zone in addition to the dead zone. The predetermined OCV drive duty is individually and concretely determined theoretically, experimentally, empirically, and simulation so that the deviation between the target displacement angle and the actual displacement angle is small even when the dead zone is not specified. Can be requested.

  As a result, as described above, the variable valve mechanism is more appropriately driven by the OCV corresponding to whether or not the learning processing for specifying the dead zone in a learning manner has been completed. Thereby, the influence of a dead zone can be reduced and the responsiveness of OCV with respect to a variable valve mechanism can be improved. Thus, for example, when the target displacement angle of the variable valve mechanism changes according to the operating state of the internal combustion engine, the actual displacement angle can be followed quickly and accurately to the changed target displacement angle. The operating state of the engine can be stabilized. As a result, deterioration of drivability such as occurrence of engine stop and engine vibration can be effectively prevented.

  If the OCV drives the variable valve mechanism under the control of the control device 40 without considering whether or not the learning process for identifying the dead zone in a learning manner has been completed, the dead zone range may be identified. The upper limit value of the dead zone in which the dead zone is ignored or estimated to be low (the OCV drive duty amount “β ′” in the dead zone when learning is not completed in FIG. 7 or the upper limit of the dead zone when learning is not completed in FIG. 7) There is a possibility that the variable valve mechanism is driven by the OCV drive duty (see the OCV drive duty “d” when learning is not completed in FIG. 7) based on the value “b”. For this reason, even if the OCV drive duty amount outside the dead zone in FIG. 7 where the OCV drive duty amount outside the dead zone is the same value in this embodiment and the comparative example, the displacement angle of the variable valve mechanism is the same. There is a possibility that the changing responsiveness will be significantly reduced. Specifically, the displacement speed Vx at the completion of learning corresponding to the OCV drive duty “d” when learning is not completed in FIG. 7 corresponds to the OCV drive duty “c” when learning is completed in FIG. It becomes smaller than the displacement speed Va when learning is completed.

  For this reason, for example, even when the target displacement angle of the variable valve mechanism changes according to the operating state of the internal combustion engine, a state in which the deviation between the target displacement angle and the actual displacement angle of the variable valve mechanism is large is long. The possibility of continuing arises. For this reason, the operating state of the internal combustion engine becomes unstable, and there is a possibility that drivability such as occurrence of engine stop or engine vibration may deteriorate.

(Second Embodiment)
Next, the operation principle of the hydraulic system for the variable valve mechanism according to the second embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the flow of control processing of the hydraulic system that is an example of the control device for the variable valve mechanism according to the second embodiment. In addition, the same step number is attached | subjected to the process similar to the control process shown by above-mentioned FIG. 5, and those description is abbreviate | omitted suitably. The control process is repeatedly executed by the control device 40 at a predetermined cycle such as several tens of microseconds or several microseconds.

  As shown in FIG. 8, when it is determined that the deviation between the target displacement angle and the actual displacement angle is larger than the first threshold as a result of the determination in step S103 through steps S101 to S103 described above (step S103). S103: Yes) Further, under the control of the control device 40, it is determined whether or not the displacement speed of the hydraulic actuator that drives the variable valve mechanism has changed from a state larger than the third threshold value to a state smaller than the third threshold value. (Step S201). Here, the third threshold value according to the second embodiment may typically mean the displacement speed of the hydraulic actuator that drives the variable valve mechanism that can change the operating state of the internal combustion engine. . Subsequently, the above-described steps S105 to S109 are performed.

  Accordingly, it is possible to appropriately determine whether or not the learning process for learning the dead zone range has been completed based on the displacement speed of the hydraulic actuator that drives the variable valve mechanism.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and a variable valve mechanism with such a change. These control devices are also included in the technical scope of the present invention.

It is the block diagram which showed the structure of the hydraulic system which is an example of the control apparatus of the variable valve mechanism which concerns on this embodiment. Schematic diagrams conceptually showing three types of operations in an oil control valve (OCV) constituting the hydraulic system according to the present embodiment (FIGS. 2A, 2B, and 2C). )). Correlation between the amount of change in the position of the spool in the oil control valve according to the present embodiment and the change in the opening length between the ports supplying or discharging the lubricating oil to the advance side oil chamber or the retard side oil chamber It is the graph which showed. FIG. 6 is a characteristic diagram showing the correlation between the OCV drive duty and the displacement speed of the hydraulic actuator in the hydraulic system of the variable valve mechanism according to the present embodiment. It is the flowchart which showed the flow of the control processing of the hydraulic system which is an example of the control apparatus of the variable valve mechanism which concerns on this embodiment. It is the graph which showed the change with time passage of the displacement angle of the variable valve mechanism concerning this embodiment. FIG. 5 is a characteristic diagram showing a correlation between an OCV drive duty and a displacement speed of a hydraulic actuator that drives the variable valve mechanism in the hydraulic system of the variable valve mechanism according to the present embodiment and a comparative example. It is the flowchart which showed the flow of the control processing of the hydraulic system which is an example of the control apparatus of the variable valve mechanism based on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Oil control valve, 12 ... Spool, 14 ... Solenoid, 16 ... Spring, 18 ... Sleeve, 20 ... Hydraulic actuator, 22 ... Housing, 24 ... Rotor, 26 ... Advance side oil chamber, 28 ... Delay side oil chamber , 30 ... Oil pump, 32 ... Oil tank, 40 ... Control device, 42 ... Crank angle sensor, 44 ... Cam angle sensor, 46 ... Oil temperature sensor.

Claims (6)

A variable valve mechanism capable of changing the valve characteristics of the internal combustion engine;
Drive means for driving the variable valve mechanism with the lubricating oil of the internal combustion engine;
A specifying means for specifying a dead zone in which there is no responsiveness in which the valve characteristic changes according to a change in the driving amount of the driving means or the responsiveness is in a range of the driving amount that is lower than a predetermined value;
When the dead zone is specified, the driving means is controlled to drive the variable valve mechanism according to the range of the specified dead zone. When the dead zone is not specified, the variable valve mechanism is set to a predetermined value. And a control means for controlling the drive means so as to drive with a drive amount.   When the dead zone is not specified, the control means drives the variable valve mechanism with a first drive amount obtained by changing a drive amount used within the dead zone within the range of the dead zone as the predetermined drive amount. The control device for a variable valve mechanism according to claim 1, wherein the driving means is controlled.   When the dead zone is specified, the control means is used outside the upper limit value of the dead zone and the dead zone when the valve characteristic is changed to either the advance side or the retard side. When the drive means is controlled to drive the variable valve mechanism with a second drive amount, and the valve characteristic is changed to either the advance side or the retard side, the lower end value of the dead zone The control device for a variable valve mechanism according to claim 1 or 2, wherein the drive means is controlled so as to drive the variable valve mechanism with the second drive amount. Deviation detecting means for detecting a deviation between a target value of the valve characteristic and an actual value that is an actual value of the valve characteristic;
2. The apparatus according to claim 1, further comprising a determination unit that determines whether or not the dead zone is specified in response to a temporal change in the detected deviation in addition to or instead of the detected deviation. 4. The control device for a variable valve mechanism according to claim 1.   The determination means is a first determination means for determining whether or not a deviation between the target value and the actual value is larger than a first threshold, and a first change amount of the deviation that is smaller than the first threshold. The control apparatus for a variable valve mechanism according to claim 4, further comprising a second determination unit that determines whether or not the threshold value is smaller than two threshold values. The driving means is an oil that drives the variable valve mechanism by stopping the supply or discharge of the lubricating oil in addition to or instead of changing the supply path of the lubricating oil or the discharge path of the lubricating oil. Has a control valve,
The control means controls the oil control valve so as to drive the variable valve mechanism by outputting a predetermined drive signal that brings the valve characteristic close to a target value of the valve characteristic to the oil control valve. The control device for a variable valve mechanism according to any one of claims 1 to 5.