JP2011111893A - Variable valve timing control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly vary a delay time from starting to beginning of variable valve timing control (VCT control) according to the product tolerance, aging variation, etc. of a variable valve timing device. <P>SOLUTION: At the time point when the delay time elapses after starting, the VCT control is begun and during the process in which actual valve timing reaches target valve timing by the VCT control, from whether or not the actual valve timing rapidly varies in an advance direction and exceeds the fastest operation track, the delay time is determined whether or not being insufficient. Then, when the delay time is determined to be insufficient, a time until the actual valve timing exceeds the fastest operation track after beginning of the VCT control is updated and stored in a backup RAM as a correction amount learning value of the delay time. The delay time is increased by the correction amount learning value when next starting. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable valve timing control device for an internal combustion engine having a function of locking a camshaft phase at a predetermined phase when the internal combustion engine is stopped.

  In recent years, in an internal combustion engine mounted on a vehicle, a hydraulically driven variable valve that changes the valve timing (opening and closing timing) of the intake valve and exhaust valve of the internal combustion engine for the purpose of improving output, reducing fuel consumption, and reducing exhaust emission. The number of devices equipped with timing devices is increasing. This hydraulically driven variable valve timing device calculates the control duty of a hydraulic control valve that adjusts the drive hydraulic pressure based on the deviation between the target valve timing and the actual valve timing, and drives the hydraulic control valve with the control duty. Variable valve timing control is executed to advance or retard the actual valve timing to the target valve timing by changing the flow rate (hydraulic pressure) of hydraulic oil supplied to the advance chamber and retard chamber of the variable valve timing device. I have to.

  In this system, the hydraulic pressure in the advance and retard chambers gradually drops while the internal combustion engine is stopped, and it becomes impossible to secure the hydraulic pressure that keeps the actual valve timing at a constant phase at the start, so the operation of the internal combustion engine is stopped. When locking, lock the camshaft phase with a lock pin at a predetermined lock phase (most retarded angle phase or intermediate lock phase, etc.) suitable for starting. I try to start it. Furthermore, at the time of starting, after supplying oil (hydraulic oil) to the advance chamber, the retard chamber and the unlock chamber of the variable valve timing device to raise the hydraulic pressure of the unlock chamber and unlocking the lock pin, The variable valve timing control is started to change the actual valve timing to the target valve timing.

  In recent years, in order to optimize the delay time (delay time) from the start to the start of variable valve timing control, as described in Japanese Patent Application Laid-Open No. 2008-291814, the internal combustion engine is stopped. There is one in which a delay time is calculated by a map based on time (soak time) and oil temperature. This is because the longer the stop time of the internal combustion engine, the greater the amount of oil leakage from the advance chamber and retard chamber, and the higher the oil temperature, the lower the viscosity of the oil. It takes into account the characteristics that it becomes easier to fill oil.

JP 2008-291814 A

  However, because there are product tolerances and changes over time of the variable valve timing system, it is difficult to accurately create a map that calculates the delay time, and avoiding some variation in the delay time calculated from the map. I can't. For this reason, the delay time calculated by the map may be shorter than the appropriate delay time, and in this case, the variable valve timing control is started with the lock pin unlocked incomplete after starting. Therefore, immediately after the start of the variable valve timing control, the lock pin is caught on the side edge of the lock hole, the actual valve timing does not move at all, and after a while, the lock pin is released due to the increase in hydraulic pressure in the lock release chamber. At the moment, the actual valve timing suddenly changes in the advance direction. Such a rapid change (flapping) in the actual valve timing not only causes abnormal noise, but in the worst case, it can damage the components of the variable valve timing device. There is also sex.

  As a countermeasure, it may be possible to set the delay time longer by the amount corresponding to the variation width in consideration of the delay time variation. In this case, however, the start timing of the variable valve timing control is delayed more than necessary. Therefore, the requirement for early start of variable valve timing control (optimization of delay time) cannot be satisfied.

  Therefore, the problem to be solved by the present invention is that the delay time from the start to the start of the variable valve timing control can be appropriately changed according to the product tolerance of the variable valve timing device, the change over time, etc. It is an object of the present invention to provide a variable valve timing control device for an internal combustion engine that can achieve both early start of valve timing control (optimization of delay time) and prevention of flapping of actual valve timing immediately after the start of variable valve timing control.

  In order to solve the above-mentioned problem, the invention according to claim 1 changes the actual valve timing by changing the rotational phase of the cam shaft with respect to the crankshaft of the internal combustion engine (hereinafter referred to as “camshaft phase”) using hydraulic pressure as a driving source. A variable valve timing device, a lock pin that locks the camshaft phase at a predetermined phase when the internal combustion engine is stopped, and a hydraulic control valve that controls a hydraulic pressure that drives the lock pin and the variable valve timing device. In a variable valve timing control device for an internal combustion engine that executes variable valve timing control for controlling the hydraulic control valve so that the timing matches a target valve timing, a delay from the start of the internal combustion engine to the start of the variable valve timing control The delay time has elapsed since the start of the internal combustion engine by setting the time (delay time) Delay time setting means for starting the variable valve timing control after the delay time setting means determines whether the delay time is insufficient based on the behavior of the actual valve timing after the variable valve timing control is started. When it is determined that the delay time is insufficient, the delay time used at the next start is corrected so as to increase.

  As described above, if the delay time is shorter than the appropriate delay time, the variable valve timing control is started with the lock pin unlocking incomplete after the start. The actual valve timing does not move at all because the lock pin is caught on the side edge of the lock hole, and after a while, the lock pin is released due to the increase in the hydraulic pressure in the unlocking chamber, and the actual valve timing changes rapidly. This shows unstable behavior (flapping). From this relationship, if the actual valve timing behavior after the start of variable valve timing control is monitored, it is possible to determine whether or not the delay time is insufficient depending on whether or not the actual valve timing changes abruptly. Thus, when it is determined that the delay time is insufficient, it is possible to correct the delay time to be used at the next start. This makes it possible to appropriately change the delay time according to the product tolerance of the variable valve timing device, changes over time, etc., and immediately start variable valve timing control (optimization of delay time) and immediately after the start of variable valve timing control. It is possible to achieve both the prevention of flapping of the actual valve timing.

  In this case, as in claim 2, the fastest operation trajectory is set until the actual valve timing reaches the target valve timing after the variable valve timing control is started, and the actual valve timing is the fastest operation trajectory after the variable valve timing control is started. It may be determined whether or not the delay time is insufficient based on the determination result. Here, the fastest operation trajectory means that the actual valve timing can be advanced or retarded from the lock phase to the target valve timing in a state where an appropriate hydraulic pressure (hydraulic pressure greater than a predetermined value) is supplied to the advance chamber and the retard chamber. It is an operation locus of the fastest actual valve timing. In this way, it is possible to accurately determine whether or not there is an unstable behavior (flapping) in which the lock pin is released after the variable valve timing control starts and the actual valve timing changes rapidly.

  Further, as in claim 3, when the number of start times or frequency at which the actual valve timing exceeds the fastest operation trajectory after starting variable valve timing control is counted, and the number of start times or frequency exceeds a predetermined value In addition, it may be determined that the delay time is insufficient. In this way, even if the actual valve timing fluctuates due to a temporary factor after the start of variable valve timing control, if the actual valve timing does not fluctuate after the start, it is not determined that the delay time is insufficient. That's it.

  According to another aspect of the present invention, when it is determined that the delay time is insufficient, the correction amount of the delay time is learned on the basis of the behavior of the actual valve timing after the variable valve timing control is started, and is used at the next start. The delay time may be corrected with a learning value of the correction amount. In this way, the delay time correction accuracy can be improved by the correction amount learning value.

  In this case, as in claim 5, the time from the start of the variable valve timing control until the actual valve timing exceeds the fastest operation trajectory is calculated, and the calculated time is learned as the correction amount of the delay time. In this way, the correction amount of the delay time can be learned easily and accurately.

  Further, as described in claim 6, when the lubricating oil of the internal combustion engine is changed, the delay time correction amount learning value may be returned to the initial value. When the lubricating oil of the internal combustion engine is replaced, the delay time correction amount learning value does not correspond to the replaced lubricating oil, so when the lubricating oil is replaced, the delay time correction amount learning value is set to the initial value. Thus, the correction amount corresponding to the lubricating oil after replacement can be quickly learned again.

FIG. 1 is a diagram schematically showing a variable valve timing control system according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the variable valve timing device. FIG. 3 is a flowchart (part 1) showing the flow of processing of the delay time learning correction program. FIG. 4 is a flowchart (part 2) showing the flow of processing of the delay time learning correction program. FIG. 5A shows a map for calculating the basic delay time A using the soak time and starting oil temperature as parameters, and FIG. 5B shows the basic delay time B using the oil viscosity and starting oil temperature as parameters. This is a map to be calculated. FIG. 6 is a map for calculating the oil viscosity using the integrated travel distance (or the number of start times) after engine oil replacement as a parameter. FIG. 7 is a time chart for explaining a control example when it is determined that the first temporary abnormality is detected at the first start. FIG. 8 is a time chart for explaining a control example when it is determined as the second temporary abnormality and the main abnormality is determined at the second start. FIG. 9 is a time chart for explaining a control example when the normal operation is performed with the delay time learned and corrected at the third start.

  Hereinafter, an embodiment in which the present invention is applied to an intake side valve timing control apparatus of an internal combustion engine will be described.

First, a schematic configuration of the entire engine control system will be described with reference to FIG.
The engine 11 that is an internal combustion engine transmits power from the crankshaft 12 to the intake side camshaft 16 and the exhaust side camshaft 17 via the sprockets 14 and 15 by the timing chain 13 (or timing belt). It has become. However, the intake side camshaft 16 has a variable valve timing device 18 that changes the valve timing of an intake valve (not shown) by changing the rotation phase (camshaft phase) of the intake side camshaft 16 with respect to the crankshaft 12. Is provided. The hydraulic circuit of the variable valve timing device 18 is supplied with hydraulic oil in an oil pan 19 by an oil pump 20, and the hydraulic pressure is controlled by a hydraulic control valve 21 so that the valve timing (advance value) of the intake valve. Is controlled.

  A cam angle sensor 22 that outputs a cam angle signal at a plurality of cam angles for cylinder discrimination is installed on the outer peripheral side of the intake side cam shaft 16, while a predetermined crank is provided on the outer peripheral side of the crank shaft 12. A crank angle sensor 23 is provided for outputting a crank angle signal for each angle. Output signals of the cam angle sensor 22 and the crank angle sensor 23 are input to an engine control circuit (hereinafter referred to as “ECU”) 24, and the ECU 24 calculates the actual valve timing of the intake valve and the crank angle sensor. The engine speed is calculated from the frequency of the 23 output pulses.

  Output signals from the accelerator sensor 44, the intake air amount sensor 45, the cooling water temperature sensor 46, the oil temperature sensor 47, and the like are also input to the ECU 24. The ECU 24 detects the engine operating state based on these various sensor signals, performs fuel injection control and ignition control according to the engine operating state, performs variable valve timing control, and performs actual valve timing of the intake valve. The hydraulic control valve 21 of the variable valve timing device 18 is feedback-controlled so that (the actual cam shaft phase of the intake side cam shaft 16) matches the target valve timing (target cam shaft phase of the intake side cam shaft 16).

  In addition, the ECU 24 stores non-volatile storage means such as a ROM 41 for storing data such as various programs, maps, constants, and flags, a RAM 42 for temporarily storing calculation data and the like, and a battery as a power source even when the engine is stopped. A backup RAM 43, which is a rewritable nonvolatile memory that holds data, is provided.

Next, the configuration of the variable valve timing device 18 will be described with reference to FIGS. 1 and 2.
As shown in FIG. 2, the housing 25 of the variable valve timing device 18 is fastened and fixed by bolts 26 to the sprocket 14 that is rotatably supported on the outer periphery of the intake side camshaft 16. Thereby, the rotation of the crankshaft 12 is transmitted to the sprocket 14 and the housing 25 via the timing chain 13, and the sprocket 14 and the housing 25 rotate in synchronization with the crankshaft 12. On the other hand, a rotor 27 is fastened and fixed to one end of the intake side camshaft 16 with a bolt 29 via a stopper 28. The rotor 27 is housed in the housing 25 so as to be relatively rotatable.

  As shown in FIG. 1, a plurality of vane storage chambers 30 are formed inside the housing 25, and each vane storage chamber 30 is retarded from the advance chamber 32 by the vane 31 formed on the outer peripheral portion of the rotor 27. It is partitioned into a chamber 33.

  Further, as shown in FIG. 2, when the oil pump 20 is driven by the power of the engine 11, the oil (hydraulic oil) pumped from the oil pan 19 is advanced by the intake side camshaft 14 via the hydraulic control valve 21. It is supplied to the square groove 34 and the retard groove 35. An advance oil passage 36 connected to the advance groove 34 communicates with each advance chamber 32. On the other hand, the retard oil passage 37 connected to the retard groove 35 communicates with each retard chamber 33.

  In a state where a hydraulic pressure of a predetermined pressure or higher is supplied to the advance chamber 32 and the retard chamber 33, the vane 31 is fixed by the hydraulic pressure of the advance chamber 32 and the retard chamber 33, and the housing 25 is rotated by the rotation of the crankshaft 12. The rotation is transmitted to the rotor 27 (vane 31) via the hydraulic oil, and the intake side camshaft 16 is rotationally driven integrally with the rotor 27. When the engine is stopped, the hydraulic pressure in the housing 25 decreases, and the lock pin 48 provided on the vane 31 is fitted into the lock hole 49 of the housing 25 by the spring force, so that the vane 31 is suitable for starting with respect to the housing 25. It is locked at a predetermined lock phase (for example, the most retarded phase, the intermediate lock phase, etc.) After the engine is started, when the hydraulic pressure in the lock release chamber rises above a predetermined hydraulic pressure required to release the lock state of the lock pin 48, the lock pin 48 is pushed out of the lock hole 49 by the oil pressure, and the lock state is released. The rotor 27 can rotate relative to the housing 25 (the actual valve timing can be changed).

  The hydraulic control valve 21 drives the valve body 39 in accordance with the current supplied to the linear solenoid 38 to continuously change the opening degree of each hydraulic port, thereby causing each advance chamber 32 and each retard chamber 33 to move. Increase or decrease the amount of oil supplied. As a result, the housing 25 and the rotor 27 (vane 31) are rotated relative to each other to change the rotation phase (cam shaft phase) of the intake side cam shaft 16 with respect to the crankshaft 12, thereby changing the valve timing of the intake valve. .

  During engine operation, the ECU 24 is variable so that the actual valve timing of the intake valve (actual cam shaft phase of the intake camshaft 16) matches the target valve timing (target camshaft phase of the intake camshaft 16). Variable valve timing control for feedback control of the energization amount (duty) of the hydraulic control valve 21 of the valve timing device 18 is executed. In the following description, “variable valve timing control” is expressed as “VCT control”.

  In this case, since the hydraulic pressure in the advance chamber 32 and the retard chamber 33 is gradually released while the engine 11 is stopped, it is not possible to secure a hydraulic pressure that allows the VCT control to be normally executed at the time of starting. Therefore, a delay time (delay time) from the start to the start of the VCT control is set, and the VCT control is started when the delay time has elapsed from the start. In this case, the delay time is mapped according to, for example, the stop time (soak time) of the engine 11, the oil temperature at the time of start-up, the oil viscosity, the travel distance after oil change (or the number of start-ups), the cooling water temperature, the outside air temperature, and the like. Etc. are set.

  However, since there are product tolerances and changes with time of the variable valve timing device 18, it is difficult to accurately create a map for calculating the delay time, and the delay time calculated by the map has some variation. Inevitable. For this reason, the delay time calculated by the map may be shorter than the appropriate delay time, and in this case, the VCT control is started with the lock pin 48 being unlocked incompletely after the start. Immediately after the start of the VCT control, the lock pin 48 is caught on the side edge of the lock hole 49 and the actual valve timing does not move at all. After that, the lock pin 48 is released from the lock release chamber due to a rise in hydraulic pressure in the lock release chamber. At the moment, the actual valve timing suddenly changes in the advance direction. Such an abrupt change (flapping) in the actual valve timing not only causes abnormal noise, but if it occurs repeatedly, in the worst case, the components of the variable valve timing device 18 are damaged. There is a possibility.

  As a countermeasure, it is conceivable to set the delay time longer by an amount corresponding to the variation width in consideration of variations in the delay time. In this case, however, the start timing of the VCT control is often delayed more than necessary. Therefore, the requirement for early start of VCT control (optimization of delay time) cannot be satisfied.

  Therefore, in this embodiment, the ECU 24 executes a delay time learning correction program shown in FIGS. 3 and 4 to be described later to determine whether the delay time is insufficient based on the behavior of the actual valve timing after starting the VCT control. If the delay time is determined to be insufficient, the delay time correction amount is learned based on the actual valve timing behavior after the start of the VCT control, and the delay time used at the next start is corrected. Correction is made with the learning value. The processing contents of the delay time learning correction program shown in FIGS. 3 and 4 will be described below.

  The delay time learning correction program shown in FIGS. 3 and 4 is started when the engine is started (when the ignition switch is turned on), and serves as delay time setting means in the claims. When this program is started, first, at step 101, it is determined whether or not the engine oil has been changed before the current start (during engine stop). In this determination method, for example, when an engine oil change operation is performed by a service technician at a maintenance shop, information on completion of engine oil change is written in the backup RAM 43 of the ECU 24 using an off-board diagnostic device (not shown). You can do that. In this case, in step 101, whether or not engine oil has been changed may be determined based on whether or not engine oil has been changed in the backup RAM 43.

  If it is determined in step 101 that the engine oil has been changed, the process proceeds to step 102 where the delay amount correction amount learning value stored in the backup RAM 43 is reset to an initial value (for example, 0), and the next step is performed. Proceed to 103. On the other hand, if it is determined in step 101 that the engine oil has not been replaced, the process proceeds to the next step 103 without resetting the correction amount learning value to the initial value.

  In the next step 103, after the oil temperature detected by the oil temperature sensor 47 is read, the process proceeds to step 104, and a soak time (engine stop time) from the time when the engine 11 is stopped to the current time is calculated. Here, if the engine stop time data is stored in the backup RAM 43, the engine stop time data can be retained even while the engine is stopped.

  Thereafter, the process proceeds to step 105, where an integrated travel distance (from the engine oil change to the present time) is calculated by referring to a map for calculating the oil viscosity using the integrated travel distance (or the number of start times) after the engine oil change shown in FIG. Alternatively, the oil viscosity is calculated according to the number of times of starting). The engine oil has a characteristic that the oil viscosity increases as the engine operation time becomes longer. Therefore, the oil viscosity calculation map of FIG. 6 increases the accumulated travel distance (or the number of start times) that is substitute information of the engine operation time. The oil viscosity is set so as to increase. In consideration of the characteristic that the oil viscosity decreases as the oil temperature increases, the oil temperature or its correlated temperature information (for example, cooling water temperature, etc.) is considered in addition to the accumulated travel distance (or the number of start times). The viscosity may be calculated.

  Thereafter, the routine proceeds to step 106, where a basic delay corresponding to the soak time and the starting oil temperature is referred to by referring to the map for calculating the basic delay time A using the soak time and the starting oil temperature as parameters shown in FIG. Time A is calculated. The basic delay time A calculation map of FIG. 5A is set so that the basic delay time A becomes longer as the soak time becomes longer, and the basic delay time A becomes shorter as the starting oil temperature becomes higher. This is because as the soak time becomes longer, the amount of oil leakage from the advance chamber 32 and the retard chamber 33 during the soak time increases, and as the oil temperature at the start increases, the oil viscosity decreases, and after the start. This is because it is easy to fill the advance chamber 32 and the retard chamber 33 with oil.

  Thereafter, the routine proceeds to step 107, where a basic delay according to the oil viscosity and the starting oil temperature is referred to by referring to a map for calculating the basic delay time B using the oil viscosity and the starting oil temperature as parameters shown in FIG. Time B is calculated. The basic delay time B calculation map of FIG. 5B is set such that the basic delay time B becomes longer as the oil viscosity increases, and the basic delay time B becomes shorter as the oil temperature at start-up becomes higher. This is because it becomes difficult to fill the advance chamber 32 and the retard chamber 33 with oil after the start-up as the oil viscosity increases.

  Thereafter, the routine proceeds to step 108, where the basic delay time A and the basic delay time B are added together to obtain the basic delay time (A + B) corresponding to the soak time, oil viscosity, and starting oil temperature. A three-dimensional map is calculated for calculating the basic delay time (A + B) using the soak time, oil viscosity, and starting oil temperature as parameters, and this three-dimensional map is used in accordance with the soak time, oil viscosity, and starting oil temperature. The basic delay time (A + B) may be calculated. Since there is a correlation between the starting oil temperature and the starting cooling water temperature, the starting cooling water temperature may be used instead of the starting oil temperature.

Then, in the next step 109, the delay amount correction value learning value stored in the backup RAM 43 is added to the basic delay time (A + B) to obtain the final delay time.
Delay time = basic delay time (A + B) + correction amount learning value

  Thereafter, the process proceeds to step 110, where the elapsed time after starting is counted by reading the count value of the elapsed time counter after starting, which starts the time counting operation from the time of starting. In the next step 111, the elapsed time after starting exceeds the delay time. It waits until the elapsed time after the start exceeds the delay time.

  After that, when the elapsed time after the start exceeds the delay time, the process proceeds from step 111 to step 112 in FIG. 4, the VCT control start permission flag is set to “ON”, and the actual valve timing is changed from the lock phase to the target valve timing. The VCT control to advance the angle is started.

  Thereafter, the process proceeds to step 113, and the fastest operation trajectory (see FIG. 7) until the actual valve timing reaches the target valve timing after the start of the VCT control is set based on the advance operation speed characteristic of the variable valve timing device 18. Here, the fastest operation trajectory is the fastest speed at which the actual valve timing can be advanced from the lock phase to the target valve timing in a state where appropriate hydraulic pressure (hydraulic pressure of a predetermined value or more) is supplied to the advance chamber 32 and the retard chamber 33. It is an advance operation locus of the actual valve timing.

  Then, in the next step 114, after calculating the actual valve timing based on the output signals of the cam angle sensor 22 and the crank angle sensor 23, the process proceeds to step 115, where it is determined whether or not the actual valve timing has reached the target valve timing. If it is determined that it is determined that the actual valve timing has reached the target valve timing, this program is terminated.

  If it is determined in step 115 that the actual valve timing has not reached the target valve timing, the process proceeds to step 116 to determine whether or not the actual valve timing has exceeded the fastest operation trajectory, and the actual valve timing is the fastest operation. If it is determined that the trajectory has not been exceeded, the processes in steps 114 to 116 are repeated. Thus, the process of determining whether or not the actual valve timing has exceeded the fastest operation trajectory is repeated at a predetermined cycle until the actual valve timing reaches the target valve timing.

  As a result, if it is determined in step 116 that the actual valve timing has exceeded the fastest operation trajectory, it is determined that there is a possibility that the delay time is insufficient, the process proceeds to step 117, where it is determined that there is a temporary abnormality. Set the flag to “ON”. Thereafter, the process proceeds to step 118, where the presence / absence of this abnormality is determined based on whether or not the number of times of determination of temporary abnormality exceeds a predetermined value. At this time, the presence / absence of this abnormality may be determined based on whether or not the determination frequency of the temporary abnormality (the ratio of the number of determinations of the temporary abnormality per predetermined number of start times) exceeds a predetermined value. Data of the temporary abnormality flag and the number of determinations (or determination frequency) of the temporary abnormality are stored in the backup RAM 43.

If it is determined in step 118 that the number of temporary abnormality determinations (or determination frequency) is equal to or less than a predetermined value, the present program is terminated as it is.
On the other hand, if it is determined in step 118 that the number of determinations (or determination frequency) of the provisional abnormality exceeds a predetermined value, the process proceeds to step 119, where it is determined that this abnormality is present, and this abnormality flag is set to “ON”. At the same time, the temporary abnormality flag is reset to “OFF”.

  Thereafter, the process proceeds to step 120 where the time from the start of the VCT control until the actual valve timing exceeds the fastest operation trajectory is calculated as a delay time correction amount learning value and updated and stored in the backup RAM 43. At this time, the time from the start of the VCT control until the actual valve timing exceeds the fastest operation trajectory may be measured by a time counter, or the time from the start until the actual valve timing exceeds the fastest operation trajectory is set as the target delay. A value obtained by subtracting the current delay time (the value corrected in step 109) from the target delay time may be used as the correction amount learning value.

Correction amount learning value = Time from the start of VCT control until the actual valve timing exceeds the fastest motion trajectory = Target delay time-Current delay time Target delay time = Time from start until actual valve timing exceeds the fastest motion trajectory Delay time = time from start to start of VCT control

  An execution example of the delay time learning correction program of FIGS. 3 and 4 described above will be described with reference to time charts of FIGS. The timing charts of FIGS. 7 to 9 show control examples for determining this abnormality when the temporary abnormality determination is performed twice in succession. FIG. 7 shows the first temporary abnormality in the first start. 8 is an example of control when it is determined, FIG. 8 is an example of control when it is determined as the second temporary abnormality at the second start, and this abnormality is determined, and FIG. 9 is a learning correction at the third start. It is an example of control when operating normally with the specified delay time.

  In the first start shown in FIG. 7, even if the VCT control start permission flag is set to “ON” and the VCT control is started when the delay time has elapsed from the start, the lock pin 48 immediately after the start of the VCT control. Is caught on the side edge of the lock hole 49 and the actual valve timing does not move at all. After a while, the lock pin 48 is released due to the increase in the hydraulic pressure in the unlocking chamber, and at that moment the actual valve timing suddenly increases. Unstable behavior of changing in advance direction. Thus, when the actual valve timing exceeds the fastest operation trajectory, it is determined that a temporary abnormality has occurred, and the temporary abnormality flag is set to “ON”. When the number of times of provisional abnormality determination is one, it is not yet determined that this abnormality is present, and the correction learning value of the delay time is not updated.

  In the second start shown in FIG. 8, even when the VCT control is started when the delay time has elapsed from the start, the actual valve timing does not move immediately after the start of the VCT control, just like the first start. After a while, when the lock pin 48 is released and the actual valve timing suddenly changes in the advance direction and exceeds the fastest operation trajectory, it is determined as a temporary abnormality. As a result, when the number of times of determination of the temporary abnormality is 2, it is determined that the abnormality is present, the abnormality flag is set to “ON”, and the provisional abnormality flag is reset to “OFF”. Then, the time from the start of the VCT control until the actual valve timing exceeds the fastest operation trajectory is updated and stored in the backup RAM 43 as a delay amount correction amount learning value.

  In the third start shown in FIG. 9, the delay time is set by adding the delay amount correction amount learning value stored in the backup RAM 43 to the basic delay time (A + B) (that is, the delay time is corrected for learning). ). As a result, an appropriate delay time is set, and when the delay time has elapsed from the start, the lock pin 48 is completely unlocked, and the actual valve timing becomes the target valve timing immediately after the start of the VCT control. And advance smoothly. Thus, the actual valve timing reaches the target valve timing without exceeding the fastest operation trajectory. This abnormality flag is reset to “OFF” when the VCT control is started.

  According to the present embodiment described above, whether or not the actual valve timing has suddenly changed in the advance direction and exceeded the fastest operation trajectory until the actual valve timing reaches the target valve timing after the start of the VCT control. If it is determined whether the delay time is insufficient (temporary abnormality or not) and it is determined that the delay time is insufficient, the learning correction is performed so that the delay time used at the next start is increased. Thus, the delay time can be appropriately changed according to the product tolerance of the variable valve timing device 18 and the change with time, and the VCT control can be started early (optimization of the delay time) and the actual valve timing immediately after the start of the VCT control. Both flutter prevention can be achieved.

In addition, in this embodiment, the time from the start of the VCT control until the actual valve timing exceeds the fastest operation trajectory is calculated, and the calculated time is learned as the delay time correction amount. Can be learned easily and accurately.
However, in the present invention, the correction amount of the delay time may be a predetermined constant value.

  In this embodiment, whether or not the delay time is insufficient (temporary abnormality) is determined by whether or not the actual valve timing has suddenly changed in the advance direction after the start of the VCT control and exceeded the fastest operation trajectory. For example, whether or not the delay time is insufficient (whether or not it is a temporary abnormality) depends on whether or not the advance operation speed or vibration amplitude of the actual valve timing exceeds a predetermined value after the start of the VCT control. The determination may be made. In short, it may be determined whether the delay time is insufficient (temporary abnormality) based on the behavior of the actual valve timing after the start of the VCT control.

  Further, in this embodiment, when the number of times of determination (or determination frequency) of the temporary abnormality exceeds a predetermined value, it is determined that the abnormality is insufficient (the delay time is insufficient), and the correction amount learning value of the delay time is updated. However, every time it is determined that there is a temporary abnormality, it may be determined that the delay time is insufficient, and the delay time correction amount learning value may be updated.

  In addition, the present invention is not limited to the intake-side variable valve timing control device, and can be implemented with various modifications without departing from the gist, such as being applicable to the exhaust-side variable valve timing control device.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 16 ... Intake side camshaft, 17 ... Exhaust side camshaft, 18 ... Variable valve timing device, 20 ... Oil pump, 21 ... Hydraulic control valve, 22 ... Cam angle sensor, 23 ... Crank angle Sensors 24... ECU (delay time setting means) 25. Housing 31. Vane 32. Advance chamber 33. Delay chamber 43 43 Backup RAM 46 Cooling water temperature sensor 47 Oil temperature sensor 48 ... Lock pin, 49 ... Lock hole

Claims (6)

A variable valve timing device that changes the actual valve timing by changing the rotational phase of the camshaft relative to the crankshaft of the internal combustion engine (hereinafter referred to as “camshaft phase”) using hydraulic pressure as a drive source, and the camshaft phase when the internal combustion engine is stopped And a hydraulic control valve that controls the hydraulic pressure that drives the lock pin and the variable valve timing device, and controls the hydraulic control valve so that the actual valve timing matches the target valve timing. In a variable valve timing control device for an internal combustion engine that executes variable valve timing control,
A delay time setting means for setting a delay time from the start of the internal combustion engine to the start of the variable valve timing control and starting the variable valve timing control after the delay time has elapsed from the start of the internal combustion engine;
The delay time setting means determines whether or not the delay time is insufficient based on the behavior of the actual valve timing after the start of the variable valve timing control. A variable valve timing control device for an internal combustion engine, wherein the delay time used for correction is corrected to increase.   The delay time setting means sets the fastest operation trajectory until the actual valve timing reaches the target valve timing after the variable valve timing control is started, and the actual valve timing exceeds the fastest operation trajectory after the variable valve timing control is started. 2. The variable valve timing control apparatus for an internal combustion engine according to claim 1, wherein it is determined whether or not the delay time is insufficient based on the determination result.   The delay time setting means counts the number of start times or the frequency at which the actual valve timing exceeds the fastest operation trajectory after the start of the variable valve timing control, and the start number or frequency reaches a predetermined value or more. 3. The variable valve timing control apparatus for an internal combustion engine according to claim 2, wherein the delay time is determined to be insufficient.   The delay time setting means learns the correction amount of the delay time based on the actual valve timing behavior after the start of the variable valve timing control when it is determined that the delay time is insufficient, and uses it at the next startup 4. The variable valve timing control device for an internal combustion engine according to claim 2, wherein the delay time is corrected with a learning value of the correction amount.   The delay time setting means calculates a time from the start of the variable valve timing control until the actual valve timing exceeds the fastest operation trajectory, and learns the calculated time as a correction amount of the delay time. The variable valve timing control device for an internal combustion engine according to claim 4.   6. The internal combustion engine according to claim 4, wherein the delay time setting means includes means for returning a correction amount learning value of the delay time to an initial value when the lubricating oil of the internal combustion engine is replaced. Variable valve timing control device for engine.

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