JP4330939B2 - Control device for variable valve mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a variable valve mechanism, and relates to a technique for correcting detection variation of a lift amount sensor that detects a valve lift amount that is variable by the variable valve mechanism.
[0002]
[Prior art]
Conventionally, as disclosed in Patent Document 1, for example, a variable valve mechanism that continuously changes the valve lift amount of the intake valve is provided, and the intake air amount of the internal combustion engine is controlled by changing the valve lift amount of the intake valve. An intake air amount control method is known.
[0003]
Further, when the valve lift amount is continuously changed as described above, a lift amount sensor for detecting the valve lift amount is provided so that the valve lift amount detected by the lift amount sensor matches the target valve lift amount. In addition, the variable valve mechanism was controlled.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-182563
[Problems to be solved by the invention]
By the way, a potentiometer or the like is used as the lift amount sensor. However, the correlation between the sensor output and the actual valve lift amount may vary due to mechanical and electrical variations, which lowers the accuracy of lift amount control. However, if the valve lift amount is reduced, the intake air amount may not be accurately controlled.
[0006]
In particular, when the lift amount before hitting the stopper is detected as the sensor output in the state where it hits the stopper on the maximum lift side in the variable valve mechanism, if the lift request is the maximum lift amount, it actually hits the stopper. However, the lift amount cannot be increased further, but control is performed to increase the lift amount.
[0007]
When the lift amount is further controlled while being in contact with the stopper, for example, in the case of a variable valve mechanism configured to change the lift amount by decelerating the motor rotation and rotating the movable portion, the reduction gear Wear may occur, and the power consumption may increase and the circuit and motor may generate heat.
[0008]
The present invention has been made in view of the above problems, and is capable of learning the sensor output characteristics on the maximum lift amount side, and can prevent deterioration / failure of the variable valve mechanism and increase in power consumption during learning. An object of the present invention is to provide a mechanism control device.
[0009]
[Means for Solving the Problems]
Therefore, according to the first aspect of the present invention, there is provided a variable valve mechanism that makes the valve lift amount variable, and a lift amount sensor that detects the valve lift amount by the variable valve mechanism, and the valve that is detected by the lift amount sensor. In a control apparatus for a variable valve mechanism that feedback-controls a control signal of the variable valve mechanism based on a lift amount and a target valve lift amount, the maximum lift amount regulated by a stopper in the variable valve mechanism is the target lift amount. When the lift amount detected by the lift amount sensor is equal to or greater than a predetermined value smaller than the maximum lift amount, the feedback control of the control signal of the variable valve mechanism is stopped, The control signal is switched to a predetermined control signal for changing the valve lift amount in the direction of the maximum lift amount, and the lift amount sensor of the lift amount sensor after the switching is switched. It was configured to learn the correlation between the sensor output and the valve lift amount based on the force.
[0010]
According to this configuration, when the maximum lift amount is requested from the engine operating conditions , the control signal of the variable valve mechanism is feedback-controlled so that the valve lift amount detected by the lift amount sensor matches the requested maximum lift amount. When the detection result by the sensor approaches the maximum lift amount and exceeds the predetermined value, the control signal is switched to the predetermined control signal to change the valve lift amount in the maximum lift amount direction, and the sensor output in the state of pressing against the stopper To learn.
[0011]
Therefore, by limiting the control signal during learning, it is possible to prevent deterioration and failure of the variable valve mechanism and increase in power consumption. After learning, the maximum lift amount is correctly detected by the lift amount sensor, and the valve lift amount is detected. Can be accurately controlled.
[0012]
According to a second aspect of the present invention, in the first aspect of the present invention, the number of learning times of the sensor output corresponding to the maximum lift amount is limited.
According to this configuration, for example, the number of permitted learnings during one trip is set in advance, and learning exceeding the permitted number of learnings is prohibited.
[0013]
Therefore, it is possible to avoid unnecessary repetition of learning control for maintaining the state of pressing against the stopper on the maximum lift amount side while the output of the lift amount sensor corresponding to the maximum lift amount is learned. Consumption can be prevented.
[0014]
According to a third aspect of the present invention, in the first or second aspect of the present invention, after the switch to the predetermined control signal, the lift amount detected by the lift amount sensor is larger than the previous stopper position equivalent value. Is configured to learn the output of the lift amount sensor as equivalent to the maximum lift amount when it continues for a predetermined time or more.
[0015]
According to such a configuration, the detected value of the lift amount increases to a predetermined value or more, the control signal is switched, and the state in which the lift amount detected by the lift amount sensor is larger than the previous stopper position equivalent value continues for a predetermined time or more. Then, the sensor output at that time is learned as the maximum lift amount.
[0016]
Therefore, it is possible to reliably learn the sensor output in a state where it is actually pressed against the stopper without being pressed against the stopper for an unnecessarily long time with an excessive force.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of an internal combustion engine for a vehicle according to an embodiment.
[0018]
In FIG. 1, an electronic control throttle 104 that opens and closes a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of the internal combustion engine 101, and a combustion chamber 106 is connected via the electronic control throttle 104 and the intake valve 105. Air is inhaled inside.
[0019]
The combustion exhaust is discharged from the combustion chamber 106 through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.
The exhaust valve 107 is driven to open and close by a cam 111 pivotally supported on the exhaust side camshaft 110 while maintaining a constant valve lift, valve operating angle, and valve timing.
[0020]
On the other hand, on the intake valve 105 side, a variable valve event and lift (VEL) mechanism 112 is provided as a variable valve mechanism that continuously and variably controls the valve lift amount together with the operating angle.
[0021]
Furthermore, on the intake valve 105 side, a VTC (variable valve timing mechanism that continuously variably controls the center phase of the valve operating angle of the intake valve 105 by changing the rotation phase of the intake camshaft with respect to the crankshaft. A variable valve timing control) mechanism 113 is provided.
[0022]
The VTC mechanism 113 may be provided only on the exhaust valve 107 side, or the VTC mechanism 113 may be provided on both the intake valve 105 side and the exhaust valve 107 side.
[0023]
An engine control unit (ECU) 114 incorporating a microcomputer controls the electronic control throttle 104, the VEL mechanism 112, and the VTC mechanism 113 so that a target intake air amount corresponding to the accelerator opening is obtained.
[0024]
The ECU 114 includes an air flow meter 115 that detects the intake air amount of the internal combustion engine 101, an accelerator pedal sensor APS116, a crank angle sensor 117 that extracts a rotation signal from the crankshaft 120, and a throttle sensor 118 that detects the opening TVO of the throttle valve 103b. A detection signal from a water temperature sensor 119 or the like that detects the cooling water temperature of the internal combustion engine 101 is input.
[0025]
Further, an electromagnetic fuel injection valve 131 is provided in the intake port 130 upstream of the intake valve 105 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal from the ECU 114, An amount of fuel proportional to the injection pulse width (valve opening time) is injected.
[0026]
2 to 4 show the structure of the VEL mechanism 112 in detail.
However, the structure of the variable valve mechanism that continuously and variably controls the valve lift amount and the operating angle of the intake valve 105 is not limited to that shown in FIGS.
[0027]
The VEL mechanism 112 shown in FIGS. 2 to 4 includes a pair of intake valves 105, 105, a hollow cam shaft 13 (drive shaft) rotatably supported by the cam bearing 14 of the cylinder head 11, and the cam shaft. Two eccentric cams 15 and 15 (drive cams) which are rotary cams supported by the shaft 13, a control shaft 16 rotatably supported by the same cam bearing 14 above the cam shaft 13, and the control shaft 16, a pair of rocker arms 18 and 18 supported by a control cam 17 so as to be swingable, and a pair of independent rockers disposed at upper ends of the intake valves 105 and 105 via valve lifters 19 and 19, respectively. The moving cams 20 and 20 are provided.
[0028]
The eccentric cams 15 and 15 and the rocker arms 18 and 18 are linked by link arms 25 and 25, and the rocker arms 18 and 18 and the swing cams 20 and 20 are linked by link members 26 and 26.
[0029]
The rocker arms 18, 18, the link arms 25, 25, and the link members 26, 26 constitute a transmission mechanism.
As shown in FIG. 5, the eccentric cam 15 has a substantially ring shape and includes a small-diameter cam main body 15a and a flange portion 15b integrally provided on the outer end surface of the cam main body 15a. A cam shaft insertion hole 15 c is formed through the shaft, and the shaft center X of the cam body 15 a is eccentric from the shaft center Y of the cam shaft 13 by a predetermined amount.
[0030]
The eccentric cam 15 is press-fitted and fixed to the camshaft 13 on both outer sides that do not interfere with the valve lifter 19 via a camshaft insertion hole 15c.
As shown in FIG. 4, the rocker arm 18 is bent in a substantially crank shape, and a central base 18 a is rotatably supported by the control cam 17.
[0031]
A pin hole 18d into which a pin 21 connected to the tip end of the link arm 25 is press-fitted is formed at one end 18b protruding from the outer end of the base 18a, while the inner end of the base 18a is formed. A pin hole 18e into which a pin 28 connected to one end portion 26a (described later) of each link member 26 is press-fitted is formed in the other end portion 18c projecting from the portion.
[0032]
The control cam 17 has a cylindrical shape, is fixed to the outer periphery of the control shaft 16, and the position of the axis P1 is eccentric from the axis P2 of the control shaft 16 by α as shown in FIG.
[0033]
As shown in FIGS. 2, 6, and 7, the rocking cam 20 has a substantially horizontal U shape, and a cam shaft 13 is fitted into a substantially annular base end portion 22 so as to be rotatably supported. A support hole 22a is formed through, and a pin hole 23a is formed through the end 23 located on the other end 18c side of the rocker arm 18.
[0034]
Further, a base circle surface 24a on the base end portion 22 side and a cam surface 24b extending in an arc shape from the base circle surface 24a toward the end edge side of the end portion 23 are formed on the lower surface of the swing cam 20. The circular surface 24 a and the cam surface 24 b come into contact with predetermined positions on the upper surfaces of the valve lifters 19 in accordance with the swing position of the swing cam 20.
[0035]
That is, when viewed from the valve lift characteristics shown in FIG. 8, as shown in FIG. 2, the predetermined angle range θ1 of the base circle surface 24a becomes the base circle section, and the predetermined angle range θ2 from the base circle section θ1 of the cam surface 24b changes. This is a so-called ramp section, and further, a predetermined angle range θ3 from the ramp section θ2 of the cam surface 24b is set to be a lift section.
[0036]
The link arm 25 includes an annular base portion 25a and a projecting end 25b projecting at a predetermined position on the outer peripheral surface of the base portion 25a. At the center position of the base portion 25a, the cam body of the eccentric cam 15 is provided. A fitting hole 25c is formed in the outer peripheral surface of 15a so as to be freely rotatable, and a pin hole 25d through which the pin 21 is rotatably inserted is formed in the protruding end 25b.
[0037]
Further, the link member 26 is formed in a straight line having a predetermined length, and circular pin ends 26a and 26b have pin holes 18d in the other end 18c of the rocker arm 18 and the end 23 of the swing cam 20, respectively. , 23a, and pin insertion holes 26c and 26d through which end portions of the pins 28 and 29 are rotatably inserted are formed.
[0038]
In addition, snap rings 30, 31, and 32 that restrict the axial movement of the link arm 25 and the link member 26 are provided at one end of each pin 21, 28, and 29.
[0039]
In the above configuration, the valve lift amount changes as shown in FIGS. 6 and 7 depending on the positional relationship between the axis P2 of the control shaft 16 and the axis P1 of the control cam 17, and the control shaft 16 is rotated. By driving, the position of the axis P2 of the control shaft 16 with respect to the axis P1 of the control cam 17 is changed.
[0040]
The control shaft 16 is configured to be rotationally driven by a DC servo motor (actuator) 121 within a predetermined rotational angle range limited by a stopper with the configuration shown in FIG. Is changed by the actuator 121, the valve lift amount and the valve operating angle of the intake valve 105 are continuously changed (see FIG. 9).
[0041]
In FIG. 10, the DC servo motor 121 is arranged so that its rotation shaft is parallel to the control shaft 16, and a bevel gear 122 is pivotally supported at the tip of the rotation shaft. On the other hand, a pair of stays 123a and 123b are fixed to the tip of the control shaft 16, and a nut 124 is swingably supported around an axis parallel to the control shaft 16 connecting the tips of the pair of stays 123a and 123b. The
[0042]
A bevel gear 126 meshed with the bevel gear 122 is pivotally supported at the tip of the screw rod 125 meshed with the nut 124, and the screw rod 125 is rotated by the rotation of the DC servo motor 121. The position of the nut 124 that meshes with the 125 is displaced in the axial direction of the screw rod 125 so that the control shaft 16 is rotated.
[0043]
Here, the direction in which the position of the nut 124 is brought closer to the bevel gear 126 is a direction in which the valve lift amount is reduced, and conversely, the direction in which the position of the nut 124 is moved away from the bevel gear 126 is a direction in which the valve lift amount is increased. ing.
[0044]
As shown in FIG. 10, a potentiometer type angle sensor 127 for detecting the angle of the control shaft 16 is provided at the tip of the control shaft 16, and the actual angle detected by the angle sensor 127 is the target angle. The ECU 114 feedback-controls the DC servo motor 121 so as to match the above.
[0045]
Here, since the valve lift amount of the intake valve 105 is determined by the angle of the control shaft 16, the angle sensor 127 corresponds to the lift amount sensor in this embodiment.
[0046]
In the present embodiment, the direction in which the angle of the control shaft 16 recognized by the angle sensor 127 increases is the direction in which the valve lift amount increases.
Further, the stopper member 128 that protrudes from the outer periphery of the control shaft 16 abuts against a receiving member (not shown) on the fixed side in both the increasing direction and the decreasing direction of the lift so that the rotation range of the control shaft 16 is reached. This regulates the minimum lift amount and the maximum lift amount.
[0047]
Next, the configuration of the VTC mechanism 113 will be described with reference to FIG.
However, the VTC mechanism 113 is not limited to the one shown in FIG. 11, and any structure that continuously changes the rotational phase of the camshaft with respect to the crankshaft may be used.
[0048]
The VTC mechanism 113 in this embodiment is a vane type variable valve timing mechanism, and is connected to a cam sprocket 51 (timing sprocket) that is driven to rotate by a crankshaft 120 via a timing chain, and an end portion of the intake camshaft 13. A rotating member 53 that is fixed and rotatably accommodated in the cam sprocket 51, a hydraulic circuit 54 that rotates the rotating member 53 relative to the cam sprocket 51, and a relative relationship between the cam sprocket 51 and the rotating member 53. And a lock mechanism 60 that selectively locks the rotational position at a predetermined position.
[0049]
The cam sprocket 51 includes a rotating part (not shown) having a tooth part meshed with a timing chain (or timing belt) on the outer periphery, and a housing that is disposed in front of the rotating part and rotatably accommodates the rotating member 53. 56, and a front cover and a rear cover (not shown) for closing the front and rear openings of the housing 56.
[0050]
The housing 56 has a cylindrical shape with openings at the front and rear ends, and has a trapezoidal shape in cross section on the inner peripheral surface, and four partition walls 63 provided along the axial direction of the housing 56 are spaced by 90 °. It is projecting at.
[0051]
The rotating member 53 is fixed to the front end portion of the intake side camshaft 14, and four vanes 78 a, 78 b, 78 c, 78 d are provided on the outer peripheral surface of the annular base 77 at 90 ° intervals.
[0052]
Each of the first to fourth vanes 78a to 78d has a substantially inverted trapezoidal cross section, and is disposed in a recess between the partition walls 63. The recesses are separated from each other in the rotational direction, and the vanes 78a to 78d. An advance side hydraulic chamber 82 and a retard side hydraulic chamber 83 are formed between both sides and both side surfaces of each partition wall 63.
[0053]
The lock mechanism 60 is configured such that the lock pin 84 engages with an engagement hole (not shown) at the rotation position (reference operation state) on the maximum retard angle side of the rotation member 53.
[0054]
The hydraulic circuit 54 includes two systems, a first hydraulic passage 91 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 82 and a second hydraulic passage 92 that supplies and discharges hydraulic pressure to the retard side hydraulic chamber 83. These hydraulic passages 91 and 92 are connected to a supply passage 93 and drain passages 94a and 94b through passage switching electromagnetic switching valves 95, respectively.
[0055]
The supply passage 93 is provided with an engine-driven oil pump 97 that pumps oil in the oil pan 96, while the downstream ends of the drain passages 94 a and 94 b communicate with the oil pan 96.
[0056]
The first hydraulic passage 91 is connected to four branch passages 91 d that are formed substantially radially in the base 77 of the rotating member 53 and communicate with the advance-side hydraulic chambers 82. It is connected to four oil holes 92 d that open to the retard side hydraulic chamber 83.
[0057]
The electromagnetic switching valve 95 is configured such that an internal spool valve body relatively switches and controls the hydraulic passages 91 and 92, the supply passage 93, and the drain passages 94a and 94b.
[0058]
The ECU 114 controls the energization amount for the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal on which a dither signal is superimposed.
[0059]
For example, when a control signal (OFF signal) with a duty ratio of 0% is output to the electromagnetic actuator 99, the hydraulic oil pressure-fed from the oil pump 47 is supplied to the retard-side hydraulic chamber 83 through the second hydraulic passage 92. At the same time, the hydraulic oil in the advance side hydraulic chamber 82 is discharged from the first drain passage 94 a into the oil pan 96 through the first hydraulic passage 91.
[0060]
Therefore, the internal pressure of the retard side hydraulic chamber 83 is high and the internal pressure of the advance side hydraulic chamber 82 is low, and the rotating member 53 rotates to the maximum retard side via the vanes 78a to 78b. The opening period (opening timing and closing timing) of the intake valve 105 is delayed.
[0061]
On the other hand, when a control signal (ON signal) with a duty ratio of 100% is output to the electromagnetic actuator 99, the hydraulic oil is supplied into the advance side hydraulic chamber 82 through the first hydraulic passage 91 and the retard side hydraulic pressure is supplied. The hydraulic oil in the chamber 83 is discharged to the oil pan 96 through the second hydraulic passage 92 and the second drain passage 94b, and the retard side hydraulic chamber 83 becomes low pressure.
[0062]
For this reason, the rotating member 53 rotates to the maximum advance side via the vanes 78a to 78d, and thereby the opening period (opening timing and closing timing) of the intake valve 105 is advanced.
[0063]
The variable valve timing mechanism is not limited to the vane type described above. For example, as disclosed in Japanese Patent Application Laid-Open No. 2001-041013 and Japanese Patent Application Laid-Open No. 2001-164951, an electromagnetic clutch (electromagnetic brake) is used. A variable valve timing mechanism configured to change the rotational phase of the camshaft relative to the crankshaft by friction braking, or a variable valve timing mechanism operated by a hydraulic gear disclosed in Japanese Patent Laid-Open No. 9-195840 may be used. .
[0064]
In the control of the VEL mechanism 112, the valve lift amount detected by the angle sensor 127 is set so that the angle of the control shaft 16 detected by the angle sensor 127 coincides with the target angle. The DC servo motor 121 is feedback controlled so as to match the amount.
[0065]
However, in the angle sensor 127 as a potentiometer, the correlation between the sensor output and the actual valve lift amount varies due to mechanical and electrical variations, and the accuracy of the valve lift amount control decreases due to the variations.
[0066]
Therefore, in this embodiment, the correlation between the sensor output and the actual valve lift amount is learned as shown below.
The flowchart of FIG. 12 shows the main routine of the learning control on the low lift side. In step S1, it is determined whether or not the learning permission condition on the low lift side is satisfied. In step S2, the VTC mechanism 113 is determined. A process for operating the valve timing is performed.
[0067]
In step S3, a process of pressing the VEL mechanism 112 against the stopper position so as to minimize the valve lift amount is performed. In step S4, a process of learning the output of the angle sensor 127 when the valve lift amount is minimum. To do.
[0068]
The flowchart of FIG. 13 shows the low lift side learning permission condition determination process in step S1 in detail.
In step S101, it is determined whether or not the coolant temperature vTWN is equal to or higher than a predetermined temperature (for example, 80 ° C.).
[0069]
In the cold state where the coolant temperature vTWN is lower than the predetermined temperature, the process proceeds to step S106, and 0 is set to the low lift side learning permission condition flag fVTMNLRGO.
On the other hand, if the cooling water temperature vTWN is equal to or higher than the predetermined temperature, the process proceeds to step S102 to determine whether or not the fuel is being cut.
[0070]
In the present embodiment, so-called decelerating fuel cut for stopping fuel injection by the fuel injection valve 131 is performed in a deceleration operation state where the accelerator is fully closed and the engine rotational speed is equal to or higher than a predetermined speed. In S102, it is determined whether or not the deceleration fuel cut is in progress.
[0071]
When the fuel cut is not in progress, the process proceeds to step S106, and 0 is set to the low lift side learning permission condition flag fVTMNLRGO.
On the other hand, if the fuel is being cut, the routine proceeds to step S103, where it is determined whether or not the engine speed vKNRPM (rpm) is equal to or lower than the first speed (for example, 3000 rpm).
[0072]
When the engine speed vKNRPM (rpm) exceeds the first speed, the process proceeds to step S106, and 0 is set to the low lift side learning permission condition flag fVTMNLRGO.
On the other hand, if the engine speed vKNRPM (rpm) is equal to or lower than the first speed, the process proceeds to step S104, where the engine speed vKNRPM (rpm) is a second speed (for example, 1000 rpm) lower than the first speed. It is determined whether or not this is the case.
[0073]
When the engine speed vKNRPM (rpm) is lower than the second speed, the process proceeds to step S106, and 0 is set to the low lift side learning permission condition flag fVTMNLRGO.
On the other hand, if the engine speed vKNRPM (rpm) is equal to or higher than the second speed, the process proceeds to step S105, and 1 is set to the low lift side learning permission condition flag fVTMNLRGO.
[0074]
The condition that the engine 101 is warmed up is to allow learning in a stable state of the engine 101, and that the condition that the engine is being cut is the valve lift amount for learning. This is because there is no significant effect on drivability even if the torque is reduced.
[0075]
Furthermore, the condition that the engine speed is within a predetermined range is that if the engine speed is high, it is impossible to avoid that the negative pressure in the cylinder exceeds the upper limit value when the valve lift is controlled to the minimum. On the other hand, if the engine speed is too low, the engine may be stalled due to the pumping loss when the valve lift amount is minimized.
[0076]
The flowchart of FIG. 14 shows the VTC operation in step S2 in detail.
In step S201, it is determined whether or not 1 is set in the low lift side learning permission condition flag fVTMNLRGO.
[0077]
If 0 is set in the low lift side learning permission condition flag fVTMNLRGO, the process proceeds to step S205, and 0 is set in the VTC operation completion flag fVTLRVTCOK.
[0078]
When the VTC operation completion flag fVTLRVTCOK is set to 0, the operation of the VTC mechanism 113 for learning is not completed, in other words, learning is performed by controlling the valve lift amount to the minimum. Indicates an incapable state.
[0079]
On the other hand, when 1 is set in the low lift side learning permission condition flag fVTMNLRGO, the process proceeds to step S202, and 0 deg which is the minimum angle is set to the target angle vVTCTRGint in the VTC mechanism 113 of the intake valve 105.
[0080]
In the present embodiment, the initial position of the intake valve 105 in the VTC mechanism 113 is the most retarded position, and the valve timing of the intake valve 105 is controlled based on the advance angle from the initial position.
[0081]
Therefore, since vVTCTRGint = 0 deg indicates that the target is the most retarded position, the setting of the target angle vVTCTRGint = 0 deg in step S202 is forcing the valve timing of the intake valve 105 toward the most retarded position. Will do.
[0082]
If the valve timing is controlled to the most retarded position while the valve lift amount of the intake valve 105 is minimum, the opening timing of the intake valve 105 is set to be after top dead center.
[0083]
In the next step S203, it is determined whether or not the actual angle of the intake valve 105 in the VTC mechanism 113 has been delayed to a predetermined angle (for example, 5 degrees) or less.
Until the actual angle of the intake valve 105 in the VTC mechanism 113 is equal to or smaller than a predetermined angle (for example, 5 deg), the process proceeds to step S205 and 0 is set to the VTC operation completion flag fVTLRVTCOK.
[0084]
When the actual angle of the intake valve 105 in the VTC mechanism 113 is delayed to a predetermined angle (for example, 5 deg) or less, the process proceeds to step S204, and 1 is set to the VTC operation completion flag fVTLRVTCOK.
[0085]
When the valve timing of the intake valve 105 is retarded and the opening timing is delayed after the top dead center, an increase in the negative pressure in the cylinder in the second half of the intake stroke is suppressed, and the negative pressure in the cylinder can be prevented from exceeding the upper limit value. .
[0086]
The flowchart of FIG. 15 shows the minimum lift control in step S3. In step S301, it is determined whether or not 1 is set in the VTC operation completion flag fVTLRVTCOK.
[0087]
When the VTC operation completion flag fVTLRVTCOK is set to 1, the low lift side learning permission conditions for the coolant temperature, fuel cut, and engine speed are satisfied, and the valve lift amount is controlled to the minimum. However, the valve timing of the intake valve 105 is retarded so that the in-cylinder negative pressure does not exceed the upper limit value.
[0088]
If it is determined in step S301 that fVTLRVTCOK = 1, the process proceeds to step S302, and the DC servo motor 121 is controlled so as to rotate the control shaft 16 of the VEL mechanism 112 toward the stopper position on the minimum lift side. .
[0089]
In step S302, since the pressing state with respect to the stopper position is maintained, the rotational driving force in the minimum lift position direction is preferably weakened. For example, the rotational driving force is driven in the minimum lift position direction with a force of about 30% duty.
[0090]
The flowchart of FIG. 16 shows the low lift side learning process in step S4. In step S401, it is determined whether or not 1 is set in the VTC operation completion flag fVTLRVTCOK.
[0091]
When 0 is set in the VTC operation completion flag fVTLRVTCOK, the process proceeds to step S406, and a predetermined time (for example, 1 second) is set in the learning delay tVELMNDLY.
[0092]
When 1 is set to the VTC operation completion flag fVTLRVTCOK, the process proceeds to step S402, where the learning delay tVELMNDLY is subtracted by a predetermined value.
Then, in the next step S403, it is determined whether or not the learning delay tVELMNDLY has been subtracted to 0, and until the learning delay tVELMNDLY becomes 0, the processing is terminated as it is from step S403, thereby the VTC operation completion flag. Learning is not performed until the predetermined time set in step S406 elapses after fVTLRVTCOK is set to 1.
[0093]
This is because there is a time lag from when the VTC operation completion flag fVTLRVTCOK is set to 1 and control is performed to minimize the valve lift amount of the intake valve 105 until the valve lift amount actually reaches the minimum value. is there.
[0094]
If it is determined in step S403 that the learning delay tVELMNDLY has been subtracted to 0, the process proceeds to step S404, where the angle vADREVEL of the control shaft 16 detected by the angle sensor 127 at that time is the low lift side learned value vVELMNLRN so far. Or less.
[0095]
Here, when the angle vADREVEL of the control shaft 16 detected by the angle sensor 127 is smaller than the low lift side learning value vVELMNLRN until then, the process proceeds to step S405, and the low lift side learning value vVELMNLRN is set to the current value. Set the detection angle vADREVEL.
[0096]
In the above description, in the learning control during the minimum lift, the valve timing of the intake valve 105 is forcibly retarded so that the negative pressure in the cylinder does not exceed the limit value. Is provided only on the exhaust valve 107 side, the valve timing of the exhaust valve 107 is forcibly retarded, and when both the intake valve 105 and the exhaust valve 107 are provided with the VTC mechanism 113, both valves By retarding the timing, the in-cylinder negative pressure can be prevented from exceeding the limit value.
[0097]
The flowcharts of FIGS. 17 and 18 show learning processing on the high lift side for learning the detection value of the angle sensor 127 at the time of maximum lift.
In step S601, it is determined whether or not the valve lift amount of the intake valve 105 required from the engine operating condition is the maximum lift amount.
[0098]
When the requested valve lift amount is the maximum lift amount, the process proceeds to step S602.
In step S602, it is determined whether or not 0 is set in the maximum lift learning end flag fVLMXLREND.
[0099]
When the maximum lift learning end flag fVLMXLREND is set to 1 and the maximum lift learning is ended, this routine is ended as it is.
If 0 is set in the maximum lift learning end flag fVLMXLREND, the process proceeds to step S603.
[0100]
In step S603, whether or not the angle vADREVEL of the control shaft 16 detected by the angle sensor 127 is equal to or greater than a predetermined angle, in other words, whether or not the valve lift amount detected by the angle sensor 127 is equal to or greater than a predetermined lift amount. Is determined.
[0101]
The predetermined angle is set so as to be an angular position before hitting the stopper on the maximum lift side even if there is a variation in detection of the angle sensor 127.
Here, if it is determined in step S603 that the detected angle vADREVEL is less than the predetermined angle, the process proceeds to step S604.
[0102]
In step S604, the DC servo motor 121 is feedback-controlled based on the deviation between the detected angle vADREVEL and the target angle corresponding to the maximum lift amount so that the detected angle vADREVEL matches the target angle corresponding to the maximum lift amount.
[0103]
On the other hand, if the detected angle vADREVEL becomes equal to or larger than the predetermined angle, the process proceeds to step S605, and the control shaft 16 is rotated to the high lift side with a constant control signal regardless of the detected angle vADREVEL.
[0104]
Specifically, for example, it is rotationally driven in the maximum lift direction with a force of about 30% ON duty, and is pressed against the stopper on the maximum lift side with a relatively weak force so as to hold the stopper position.
[0105]
In step S606, it is determined whether or not the detected angle vADREVEL is greater than or equal to the previous high lift side learned value vVELMXLRN.
When the detected angle vADREVEL is less than the previous high lift side learned value vVELMXLRN, the process proceeds to step S607, and a predetermined value is set to the learning delay tVELMXDLY.
[0106]
On the other hand, when the detected angle vADREVEL becomes equal to or higher than the previous high lift side learning value vVELMXLRN, the process proceeds to step S608, and the learning delay tVELMXDLY is subtracted by a predetermined value.
[0107]
In the next step S609, it is determined whether or not the learning delay tVELMXDLY has been subtracted to zero.
When the learning delay tVELMXDLY is subtracted to 0, the process proceeds to step S610, and the detected angle vADREVEL at that time is set to the high lift side learned value vVELMXLRN.
[0108]
In step S611, the maximum number of lift learning times vVELMXLNCT is counted up. In step S612, it is determined whether or not the maximum number of lift learning times vVELMXLNCT matches a predetermined value (for example, 10).
[0109]
When vVELMXLNCT = predetermined value (for example, 10), the process proceeds to step S613, where 1 is set in the maximum lift learning end flag fVLMXLREND so that the subsequent learning is prohibited.
[0110]
Since the maximum lift learning end flag fVLMXLREND is initially set to 0 at start-up, learning on the maximum lift side is limited to a predetermined number of times or less per trip.
[0111]
According to the above learning on the maximum lift side, since the pressing state against the stopper on the maximum lift side is held with a minimum force, deterioration / failure of the variable valve mechanism at the time of learning and increase in power consumption can be prevented. Furthermore, wasteful power consumption can be prevented by limiting the number of learnings.
[0112]
After learning, since the maximum lift state can be correctly detected based on the high lift side learned value vVELMXLRN, the valve lift amount can be controlled with high accuracy, especially when the valve lift amount is pressed against the stopper. It is possible to prevent feedback control in the direction of increasing the value.
[0113]
FIG. 19 shows a process for correctly detecting the angle (valve lift amount) of the control shaft 16 based on the learned values vVELMNLRN and vVELMXLRN (in other words, variations in the correlation between the sensor output and the actual valve lift amount). Indicates.
[0114]
In step S501, the temporary actual angle (temporary actual valve lift amount) vREVELtmp of the control shaft 16 is calculated based on the following equation.
vREVELtmp = mFULANG × (vADREVEL−vVELMNLRN) / (vVELMXLRN−vVELMNLRN)
In the above equation, mFULANG is the angle width from the maximum lift to the maximum lift that is stored in advance. The process of replacing the value is performed (see FIG. 20).
[0115]
In the next step S502, the larger of the temporary actual angle (temporary actual valve lift amount) vREVELtmp obtained in step S501 and 0 is selected, and the selected one is set in vREVELtmp.
[0116]
In step S503, the smaller of the angular width mFULANG and vREVELtmp set in step S502 is set as the final detected actual angle vREVEL. In the above embodiment, the learning of the value corresponding to the minimum lift amount is performed while the fuel is cut. However, the learning may be performed while the engine is stopped, for example.
[0117]
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.
(A) In the control device for a variable valve mechanism according to claim 3,
The variable valve mechanism is a mechanism in which a valve lift amount continuously changes according to a rotation angle of a control shaft that is rotationally driven by a motor,
When the lift amount detected by the lift amount sensor reaches a predetermined value or more, the motor is driven in a high lift direction with a predetermined ON duty.
[0118]
According to such a configuration, the maximum lift amount is defined by limiting the rotation range of the control shaft with the stopper, and when learning approaches the maximum lift, the motor that rotates the control shaft is driven in a high lift direction with a predetermined ON duty. By being driven, the control shaft is pressed against the stopper that restricts the rotation of the control shaft on the high lift side with a predetermined force.
[0119]
Accordingly, it is possible to prevent the pressing force against the stopper from being excessively controlled, and the occurrence of deterioration / failure of the variable valve mechanism and increase in power consumption.
(B) In the control device for a variable valve mechanism according to claim 2,
The control device for a variable valve mechanism, wherein the number of learning of sensor output corresponding to the maximum lift amount is limited to a predetermined number or less per trip.
[0120]
According to such a configuration, if learning of the maximum lift amount is performed a predetermined number of times during one trip from when the key switch is turned on to when it is turned off, no further learning is performed and it is pressed toward the stopper. Control to maintain the state is not performed.
[0121]
Therefore, deterioration and failure of the variable valve mechanism due to learning and increase in power consumption can be avoided while performing necessary and sufficient learning.
(C) In the control apparatus for a variable valve mechanism according to any one of claims 1 to 3, when the engine fuel is being cut and the valve lift is set to the minimum value, Under predetermined operating conditions where the pressure does not exceed a predetermined value, the valve lift amount is forcibly controlled to the minimum value, and the output of the lift amount sensor at the time of the control is learned as equivalent to the minimum lift amount, and the minimum lift amount A variable valve operating system in which a correlation between a sensor output and a valve lift amount is updated by assigning a range between a value learned as equivalent and a value learned as equivalent to the maximum lift amount to a variable range of the valve lift amount. Control device for the mechanism.
[0122]
According to this configuration, when the fuel supply to the engine is temporarily stopped (for example, during deceleration fuel cut) and the engine output is not required, the correlation between the sensor output and the valve lift amount is still present. When the valve lift amount is forcibly controlled to the minimum value to learn the valve lift, the valve lift amount is forcibly controlled to the minimum value within the variable range under the predetermined operating conditions where the negative pressure in the cylinder does not exceed the predetermined value. To do.
[0123]
Then, the sensor output in a state where the actual valve lift amount is the minimum value is learned as the minimum lift amount, and between the value learned as the minimum lift amount and the value learned as the maximum lift amount. Is assigned to the variable range of the valve lift amount, and the correlation between the sensor output and the valve lift amount is updated.
[0124]
Therefore, even if the valve lift amount is forcibly controlled to the minimum value to learn the minimum valve equivalent value, the engine operability is not affected and the oil rises due to an increase in the negative pressure in the cylinder. While the sensor output range between the minimum valve equivalent value and the maximum valve equivalent is assigned to the variable range of the valve lift amount, the valve lift amount can be accurately detected over the entire area. .
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an internal combustion engine in an embodiment.
2 is a cross-sectional view showing a VEL (Variable valve Event and Lift) mechanism (AA cross-sectional view in FIG. 3).
FIG. 3 is a side view of the VEL mechanism.
FIG. 4 is a plan view of the VEL mechanism.
FIG. 5 is a perspective view showing an eccentric cam used in the VEL mechanism.
6 is a cross-sectional view showing the operation of the VEL mechanism during low lift (cross-sectional view taken along line BB in FIG. 3).
7 is a cross-sectional view showing the operation of the VEL mechanism during high lift (BB cross-sectional view of FIG. 3).
FIG. 8 is a valve lift characteristic diagram corresponding to the base end surface of the swing cam and the cam surface in the VEL mechanism.
FIG. 9 is a characteristic diagram of valve timing and valve lift of the VEL mechanism.
FIG. 10 is a perspective view showing a rotation drive mechanism of a control shaft in the VEL mechanism.
FIG. 11 is a longitudinal sectional view showing a VTC (Variable valve Timing Control) mechanism.
FIG. 12 is a flowchart showing a main routine of low lift side learning in the embodiment.
FIG. 13 is a flowchart showing learning permission condition determination processing in the low lift side learning control;
FIG. 14 is a flowchart showing an operation process of the intake side VTC in the low lift side learning control;
FIG. 15 is a flowchart showing minimum lift control of VEL in the low lift side learning control;
FIG. 16 is a flowchart showing a learning process in the low lift side learning control;
FIG. 17 is a flowchart showing high lift side learning in the embodiment.
FIG. 18 is a flowchart showing high lift side learning in the embodiment.
FIG. 19 is a flowchart showing lift amount detection processing based on the learning results on the low lift side and the high lift side.
FIG. 20 is a diagram showing characteristics of lift amount detection processing based on the learning result;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 107 ... Exhaust valve, 112 ... VEL mechanism (variable valve mechanism), 113 ... VTC mechanism (variable valve timing mechanism), 114 ... Engine control unit (ECU)

Claims (3)

A variable valve mechanism that makes the valve lift amount variable; and a lift amount sensor that detects a valve lift amount by the variable valve mechanism; and a valve lift amount detected by the lift amount sensor and a target valve lift amount; In a variable valve mechanism control apparatus that feedback-controls a control signal of the variable valve mechanism based on
When the maximum lift amount regulated by the stopper in the variable valve mechanism is the target valve lift amount, the lift amount detected by the lift amount sensor is equal to or greater than a predetermined value smaller than the maximum lift amount. The feedback control of the control signal of the variable valve mechanism is stopped, the control signal is switched to a predetermined control signal for changing the valve lift amount in the maximum lift amount direction, and the output of the lift amount sensor after the switching is changed. A control device for a variable valve mechanism, wherein a correlation between a sensor output and a valve lift amount is learned based on the correlation. Control device for a variable valve mechanism according to claim 1, wherein limiting the number of times of learning of the sensor output corresponding to the maximum lift amount. After switching to the predetermined control signal, when the lift amount detected by the lift amount sensor is larger than the previous stopper position equivalent value for a predetermined time or longer, the output of the lift amount sensor is set to the maximum lift. 3. The control device for a variable valve mechanism according to claim 1, wherein learning is performed as an amount equivalent.

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