JP2009293580A - Abnormality diagnostic device of variable valve timing control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect abnormality in which a locking mechanism is naturally unlocked in a low oil pressure state where a camshaft phase (valve timing) cannot be normally controlled by a hydraulic drive type variable valve timing device in a system equipped with the locking mechanism for locking the camshaft phase. <P>SOLUTION: When the abnormality in which the locking mechanism 45 is unlocked occurs and an actual camshaft phase is varied in the low oil pressure state where the camshaft phase cannot be normally controlled, deviation between a target camshaft phase and the actual camshaft phase becomes large. By paying attention to this point, it is determined whether the state is in the low oil pressure state or not based on a cooling water temperature, and when it is determined as being in the low oil pressure state, an integrated value of the deviation between the target camshaft phase and the actual camshaft phase is calculated, and the integrated value is compared with an abnormality determination value, and abnormality of the locking mechanism 45 is determined. Thus, the abnormality can be detected when the abnormality in which the locking mechanism 45 is naturally unlocked in the low oil pressure state where the camshaft phase cannot be normally controlled occurs. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a variable valve timing control system including a variable valve timing device that changes a rotational phase (cam shaft phase) of a cam shaft with respect to a crankshaft of an internal combustion engine, and a phase maintaining mechanism that maintains the cam shaft phase at a predetermined position. It is invention regarding the abnormality diagnosis apparatus of this.

  In recent years, internal combustion engines mounted on vehicles have adopted variable valve timing devices that change the valve timing (open / close timing) of intake valves and exhaust valves for the purpose of improving output, reducing fuel consumption, and reducing exhaust emissions. It is increasing. A variable valve timing device that is currently in practical use changes the valve timing of an intake valve or an exhaust valve that is driven to open and close by the camshaft by changing the rotational phase (camshaft phase) of the camshaft with respect to the crankshaft. Many are structured.

  In general, a hydraulically driven variable valve timing device adjusts the camshaft phase (valve timing) until the rotational speed of the internal combustion engine (that is, the rotational speed of the oil pump) increases and the hydraulic oil pressure reaches a certain level. It cannot be controlled normally.

  Therefore, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2001-159330), when the internal combustion engine is stopped, the cam shaft phase is set in advance to a predetermined lock position (for example, a position suitable for starting) by a lock mechanism. The internal combustion engine is started with the camshaft phase maintained at the locked position even in a low hydraulic pressure state where the camshaft phase cannot be normally controlled at the next start to ensure startability. As the hydraulic pressure of the hydraulic oil rises as the engine speed (that is, the oil pump speed) increases and the camshaft phase can be controlled normally, the camshaft phase is unlocked by the lock mechanism. There is something that was made.

Further, as a technique for diagnosing abnormality of the variable valve timing device, as described in Patent Document 2 (Japanese Patent Laid-Open No. 11-2141), a predetermined time has elapsed after the target camshaft phase has changed in a step shape. In some cases, whether or not there is an abnormality in the responsiveness of the variable valve timing device is determined depending on whether or not the deviation between the target cam shaft phase and the actual cam shaft phase at that time is greater than or equal to a predetermined value.
JP 2001-159330 A (pages 5 to 6 etc.) Japanese Patent Laid-Open No. 11-2141 (second page, etc.)

  By the way, in the variable valve timing control system provided with the lock mechanism described in Patent Document 1, when the camshaft phase cannot be normally controlled at the time of starting the internal combustion engine or the like, the camshaft phase is controlled by the lock mechanism. Although it should be maintained in the locked position, if an abnormality occurs in which the locking mechanism is unlocked due to vibration during cranking, the actual camshaft phase (actual valve timing) fluctuates and moves to an unintended position. Therefore, the startability of the internal combustion engine and the rotational speed stability after the start may be adversely affected.

  However, the abnormality diagnosis technique disclosed in Patent Document 2 is a variable valve timing device during camshaft phase control that is executed after the hydraulic pressure of hydraulic oil rises to a hydraulic pressure region in which the camshaft phase can be normally controlled after the internal combustion engine is started. This is a technology for determining whether there is an abnormality in the responsiveness of the camshaft, and an abnormality has occurred in a phase maintenance mechanism such as a lock mechanism that maintains the camshaft phase in a predetermined position when the camshaft phase is in a low oil pressure state where the camshaft phase cannot be controlled normally However, the abnormality cannot be detected.

  The present invention has been made in view of such circumstances, and therefore, the object of the present invention is when a phase maintaining mechanism abnormality occurs in a low hydraulic pressure state where the camshaft phase cannot be normally controlled. An object of the present invention is to provide an abnormality diagnosis device for a variable valve timing control system that can detect the abnormality.

  In order to achieve the above object, the invention according to claim 1 is a hydraulically driven variable that changes the 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”). In an abnormality diagnosis device for a variable valve timing control system comprising a valve timing device and a phase maintaining mechanism that maintains a camshaft phase at a predetermined position in a low hydraulic pressure state where at least the camshaft phase cannot be normally controlled. Is determined by the low hydraulic pressure state determination means, and abnormality diagnosis means for determining whether the phase maintaining mechanism is abnormal based on the target cam shaft phase and the actual cam shaft phase when it is determined that the low hydraulic pressure state is determined It is made to judge by.

  In general, in a low hydraulic pressure state where the cam shaft phase cannot be controlled normally, if the phase maintaining mechanism functions normally, the actual cam shaft phase is maintained at a predetermined position (= target cam shaft phase) by the phase maintaining mechanism. Although the actual cam shaft phase matches the target cam shaft phase, if the phase maintaining mechanism malfunctions and the actual cam shaft phase fluctuates, the actual cam shaft phase does not match the target cam shaft phase. Therefore, as in the present invention, by using the target cam shaft phase and the actual cam shaft phase that are determined to be in the low hydraulic pressure state, it is possible to accurately determine whether there is an abnormality in the phase maintaining mechanism. When an abnormality occurs in the phase maintaining mechanism in the hydraulic state, the abnormality can be detected.

  For example, when the present invention is applied to a system having a hydraulic sensor that detects the hydraulic pressure of hydraulic oil of a variable valve timing device as in claim 2, is the low hydraulic pressure state based on the output of the hydraulic sensor? It is better to determine whether or not. In this way, by determining whether the hydraulic pressure detected by the hydraulic pressure sensor is lower than the predetermined lower limit value (lower limit value of the hydraulic pressure range in which the camshaft phase can be normally controlled), the camshaft phase is set to normal. It is possible to accurately determine whether or not the low hydraulic pressure state cannot be controlled.

  Further, when the present invention is applied to a system having an oil temperature sensor for detecting the oil temperature of the hydraulic oil of the variable valve timing device as in claim 3, the low hydraulic pressure state is determined based on the output of the oil temperature sensor. It may be determined whether or not. Generally, when the oil temperature decreases, the viscosity of the hydraulic oil increases and the hydraulic pressure supplied to the variable valve timing device decreases. Therefore, the oil temperature is a parameter for evaluating the hydraulic pressure. Therefore, if the oil temperature detected by the oil temperature sensor is used, it can be accurately estimated whether or not the oil pressure is lower than the predetermined lower limit value, and it can be determined whether or not the oil pressure state is low.

  Further, when the present invention is applied to a system having a cooling water temperature sensor for detecting the cooling water temperature of the internal combustion engine as in claim 4, whether or not the low hydraulic pressure state is determined based on the output of the cooling water temperature sensor. May be determined. Generally, since the coolant temperature and the oil temperature change according to the temperature of the internal combustion engine, the coolant temperature serves as substitute information for the oil temperature and is a parameter for evaluating the hydraulic pressure. Therefore, if the coolant temperature detected by the coolant temperature sensor is used, it can be accurately estimated whether or not the hydraulic pressure is lower than the predetermined lower limit value, and it can be determined whether or not the low hydraulic pressure state is established. In addition, since a cooling water temperature sensor mounted on a general internal combustion engine control system can be used, there is no need to newly install a hydraulic sensor or an oil temperature sensor, which is an important technical issue in recent years. The demand for cost can be satisfied.

  Further, the low hydraulic pressure determination time is set according to the coolant temperature detected by the coolant temperature sensor (and / or the oil temperature detected by the oil temperature sensor) at the time of starting the internal combustion engine, as in claim 5. Whether or not the low hydraulic pressure state is established may be determined based on whether or not the elapsed time after starting is within the low hydraulic pressure state determination time. In general, the hydraulic pressure rises according to the elapsed time after starting the internal combustion engine, and the time until the hydraulic pressure rises to a predetermined lower limit value changes according to the coolant temperature and the oil temperature at the time of startup. Therefore, it is possible to determine whether or not the engine is in the low hydraulic pressure state based on whether or not the elapsed time after starting the internal combustion engine is within the low hydraulic pressure determination time set in accordance with the cooling water temperature or the oil temperature at the time of starting. it can.

  In addition, the abnormality determination method for the phase maintaining mechanism is configured to determine whether there is an abnormality in the phase maintaining mechanism using a deviation between the target cam shaft phase and the actual cam shaft phase or an integrated value of the deviation. Anyway. When an abnormality occurs in the phase maintaining mechanism and the actual cam shaft phase fluctuates, the actual cam shaft phase does not match the target cam shaft phase, so that the deviation between the target cam shaft phase and the actual cam shaft phase increases. Therefore, if the deviation between the target cam shaft phase and the actual cam shaft phase or the integrated value of the deviation is evaluated, the presence / absence of an abnormality in the phase maintaining mechanism can be accurately determined.

  Further, as in claim 7, the presence / absence of abnormality of the phase maintaining mechanism may be determined using the locus length of the target cam shaft phase and the locus length of the actual cam shaft phase. When an abnormality occurs in the phase maintaining mechanism and the actual cam shaft phase fluctuates, the trajectory length of the actual cam shaft phase (the integrated value of the change amount) becomes larger than the trajectory length of the target cam shaft phase. Therefore, if the trajectory length of the target cam shaft phase and the trajectory length of the actual cam shaft phase are used, it is possible to accurately determine whether or not the phase maintaining mechanism is abnormal.

  Several embodiments embodying the best mode for carrying out the present invention will be described below.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 that detects the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided. A cooling water temperature sensor 26 that detects the cooling water temperature and a knock sensor 27 that detects knocking vibration are attached to the cylinder block of the engine 11.

  Next, a schematic configuration of the variable valve timing control system will be described based on FIG. The engine 11 is configured such that power from the crankshaft 28 is transmitted to the intake side camshaft 32 and the exhaust side camshaft 33 via the sprockets 30 and 31 by the timing chain 29 (or timing belt). The intake side camshaft 32 is provided with a hydraulically driven variable valve timing device 34, and this variable valve timing device 34 changes the rotation phase of the intake side camshaft 32 relative to the crankshaft 28 (hereinafter referred to as “camshaft phase”). By changing, the valve timing of the intake valve 35 (see FIG. 1) that is driven to open and close by the intake side camshaft 32 is changed.

  The housing 36 of the variable valve timing device 34 is provided so as to rotate integrally with the sprocket 30, and the sprocket 30 and the housing 36 rotate in synchronization with the crankshaft 28. On the other hand, the vane rotor 37 disposed in the housing 36 is provided so as to rotate integrally with the intake side camshaft 32. A plurality of vane storage chambers 38 are formed inside the housing 36, and a plurality of vanes 39 are formed on the outer periphery of the vane rotor 37. The vane storage chambers 38 are respectively connected to the advance chambers 40 by the vanes 39. It is partitioned into a retarding chamber 41.

  When the oil pump 42 is driven by the power of the engine 11, hydraulic oil (oil) pumped from the oil pan 43 is supplied to the advance chamber 40 and the retard chamber 41 via the hydraulic control valve 44. In a state where hydraulic pressure of a predetermined pressure or higher is supplied to the advance chamber 40 and the retard chamber 41, the vane 39 is held by the hydraulic pressure of the advance chamber 40 and the retard chamber 41, and the housing is rotated by the rotation of the crankshaft 28. The rotation of 36 is transmitted to the vane rotor 37 via hydraulic pressure, and the intake side camshaft 32 is rotationally driven integrally with the vane rotor 37. By controlling the hydraulic pressure supplied to the advance chamber 40 and the hydraulic pressure supplied to the retard chamber 41 by the hydraulic control valve 44 and rotating the vane rotor 37 relative to the housing 36, the intake camshaft 32 relative to the crankshaft 28 is controlled. The valve timing is changed by changing the rotation phase (cam shaft phase).

  The variable valve timing device 34 is provided with a lock mechanism 45 (phase maintaining mechanism) for locking the camshaft phase when the engine is stopped or started. The lock mechanism 45 is provided with a lock pin on any one vane 39, and the lock pin fits into a lock hole provided in the housing 36, thereby locking the camshaft phase at a predetermined lock position. It is configured as follows. This lock position is set to a position suitable for starting (for example, a substantially intermediate position in the adjustable range of the cam shaft phase).

  In general, the hydraulically driven variable valve timing device 34 determines the camshaft phase (valve timing) only after the engine rotational speed (that is, the rotational speed of the oil pump 42) has increased and the hydraulic oil pressure has increased to some extent. Since the engine 11 cannot be normally controlled, the cam shaft phase is locked at a predetermined lock position by the lock mechanism 45 in advance when the engine 11 is stopped. Even in a hydraulic state, the engine 11 is started in a state where the camshaft phase is maintained at the locked position to ensure startability. Thereafter, the hydraulic pressure of the hydraulic oil increases as the engine rotational speed (that is, the rotational speed of the oil pump 42) increases. The lock mechanism 45 unlocks the camshaft phase after the hydraulic pressure is reached so that the camshaft phase can be normally controlled.

  A cam angle sensor 48 that outputs a cam angle signal for each predetermined cam angle is attached to the outer peripheral side of the intake cam shaft 32, and a crank angle for each predetermined crank angle is provided on the outer peripheral side of the crankshaft 28. A crank angle sensor 49 for outputting a signal is attached. The engine speed is detected based on the output signal of the crank angle sensor 49, and the actual cam shaft phase is detected based on the output signal of the cam angle sensor 48 and the output signal of the crank angle sensor 49.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 50. The ECU 50 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 21 according to the engine operating state, The ignition timing of the spark plug 22 is controlled.

  Further, the ECU 50 executes a valve timing control routine (not shown) to calculate a target cam shaft phase (target valve timing) according to the engine operating state and the like, and outputs an output signal from the cam angle sensor 48 and the crank angle sensor 49. The actual cam shaft phase (actual valve timing) is calculated on the basis of the output signal and the hydraulic control valve 44 of the variable valve timing device 34 is controlled so that the actual cam shaft phase matches the target cam shaft phase.

  By the way, in the variable valve timing control system provided with the lock mechanism 45, the cam shaft phase should be maintained at the lock position by the lock mechanism 45 when the cam shaft phase cannot be normally controlled at the time of engine start or the like. However, if an abnormality occurs in which the lock mechanism 45 is unlocked by vibration during cranking or the like, the actual camshaft phase (actual valve timing) fluctuates and moves to an unintended position. Or the rotational speed stability after starting may be adversely affected.

  Therefore, the ECU 50 executes an abnormality diagnosis routine shown in FIG. 3 to be described later, and determines that the target camshaft phase and the actual camshaft phase are in a low hydraulic pressure state where the camshaft phase cannot be normally controlled. An integrated value T of the deviation is obtained, and the integrated value T is compared with an abnormality determination value to determine whether the lock mechanism 45 is abnormal.

  Generally, in a low hydraulic pressure state where the cam shaft phase cannot be controlled normally, if the lock mechanism 45 is functioning normally, the actual cam shaft phase is maintained at the lock position (= target cam shaft phase) by the lock mechanism 45. The actual camshaft phase matches the target camshaft phase, but if the actual camshaft phase fluctuates due to an abnormality that causes the lock mechanism 45 to be unlocked arbitrarily, the actual camshaft phase will not match the target camshaft phase. The deviation between the target cam shaft phase and the actual cam shaft phase becomes large. Therefore, if the integrated value T of the deviation between the target cam shaft phase and the actual cam shaft phase is compared with the abnormality determination value, the presence or absence of abnormality of the lock mechanism 45 can be accurately determined.

Hereinafter, processing contents of the abnormality diagnosis routine of FIG. 3 executed by the ECU 50 will be described.
The abnormality diagnosis routine shown in FIG. 3 is executed at a predetermined cycle while the ECU 50 is powered on, and serves as abnormality diagnosis means in the claims. When this routine is started, first, in step 101, it is determined whether or not the low hydraulic pressure state in which the camshaft phase cannot be controlled normally is as follows.

  For example, it is estimated whether or not the hydraulic pressure is lower than a predetermined lower limit hydraulic pressure (lower limit value of a hydraulic pressure range in which the camshaft phase can be normally controlled) depending on whether or not the cooling water temperature detected by the cooling water temperature sensor 26 is lower than a predetermined value. Then, it is determined whether or not it is in a low hydraulic pressure state. In general, since the cooling water temperature and the oil temperature change according to the engine temperature, the cooling water temperature serves as substitute information for the oil temperature. Further, when the oil temperature is lowered, the viscosity of the hydraulic oil is increased and the hydraulic pressure supplied to the variable valve timing device 34 is lowered. Therefore, the cooling water temperature (oil temperature substitute information) is a parameter for evaluating the hydraulic pressure. Therefore, if it is determined whether or not the coolant temperature detected by the coolant temperature sensor 26 is lower than a predetermined value, it is accurately estimated whether or not the hydraulic pressure is lower than a predetermined lower limit value, and whether or not the low hydraulic pressure state is present. Can be determined.

  Alternatively, the low hydraulic pressure state determination time is set according to the cooling water temperature detected by the cooling water temperature sensor 26 when starting the engine, and the low hydraulic pressure state is determined depending on whether or not the elapsed time after engine startup is within the low hydraulic pressure state determination time. You may make it determine whether there exists. In general, the hydraulic pressure rises according to the elapsed time after the engine is started, and the time until the hydraulic pressure rises to a predetermined lower limit value changes according to the coolant temperature and the oil temperature at the time of starting the engine. Therefore, it is determined whether or not the engine is in the low hydraulic pressure state based on whether or not the elapsed time after starting the engine is within the low hydraulic pressure determination time set in accordance with the coolant temperature at the time of engine startup (oil temperature substitute information). can do. In this case, the process of step 101 serves as a low hydraulic pressure state determination means in the claims.

  If it is determined in step 101 that the camshaft phase is in a low hydraulic pressure state where the camshaft phase cannot be controlled normally, the process proceeds to step 102 to calculate the integrated value T of the deviation between the target camshaft phase and the actual camshaft phase. The execution time counter that measures the execution time of the process is counted up. Thereafter, the process proceeds to step 103, and after calculating the deviation (absolute value) between the target cam shaft phase and the actual cam shaft phase, the process proceeds to step 104, where the deviation between the previous target cam shaft phase and the actual cam shaft phase is calculated. Add the deviation between the current target camshaft phase and actual camshaft phase to the totalized value T (n-1) to update the integrated value T (n) of the deviation between the target camshaft phase and actual camshaft phase. To do.

  Thereafter, when it is determined in step 101 that the hydraulic pressure state is not low, the routine proceeds to step 105, where the execution time of the process for calculating the integrated value T of the deviation between the target cam shaft phase and the actual cam shaft phase is a predetermined time. If it is determined whether or not the execution time is shorter than the predetermined time, it is determined that the abnormality diagnosis accuracy of the lock mechanism 45 cannot be ensured, and this routine is executed without giving an abnormality diagnosis result. finish.

  On the other hand, if it is determined in step 105 that the execution time of the process of calculating the integrated value T of the deviation between the target cam shaft phase and the actual cam shaft phase is equal to or longer than the predetermined time, the abnormality diagnosis accuracy of the lock mechanism 45 is increased. If it is determined that it can be secured, the process proceeds to step 106, where it is determined whether or not the integrated value T of the deviation between the target cam shaft phase and the actual cam shaft phase is equal to or greater than the abnormality determination value.

  If it is determined in step 106 that the integrated value T of the deviation between the target cam shaft phase and the actual cam shaft phase is greater than or equal to the abnormality determination value, the process proceeds to step 107, where there is an abnormality in the lock mechanism 45 (low hydraulic pressure). In this state, it is determined that an abnormality has occurred in which the lock of the lock mechanism 45 is automatically released), the abnormality flag is set to ON, and the processing at the time of abnormality determination is executed. For example, a warning lamp (not shown) provided on the instrument panel of the driver's seat is turned on, or a warning display section (not shown) of the instrument panel of the driver's seat is used for the processing at the time of the abnormality determination. A warning is displayed to warn the driver, and the abnormality information (abnormality code or the like) is rewritten to a rewritable nonvolatile memory such as a backup RAM (not shown) of the ECU 50 (a rewrite that retains stored data even when the ECU 50 is powered off) Memory).

  On the other hand, when it is determined in step 106 that the integrated value T of the deviation between the target cam shaft phase and the actual cam shaft phase is smaller than the abnormality determination value, the process proceeds to step 108 and the lock mechanism 45 It is determined that there is no abnormality (normal) and the abnormality flag is kept OFF.

  In the first embodiment described above, when the camshaft phase is in a low hydraulic pressure state in which the camshaft phase cannot be controlled normally and an abnormality occurs that the lock mechanism 45 is unlocked arbitrarily and the actual camshaft phase fluctuates, the target camshaft phase Focusing on the fact that the deviation between the actual camshaft phase and the actual camshaft phase is large, when it is determined that the hydraulic pressure is low, an integrated value T of the deviation between the target camshaft phase and the actual camshaft phase is obtained and Since the value T is compared with the abnormality determination value to determine whether or not there is an abnormality in the lock mechanism 45, if an abnormality occurs in which the lock mechanism 45 is unlocked in the low hydraulic pressure state, the abnormality is Can be detected.

  In the first embodiment, since the low hydraulic pressure state is determined using the cooling water temperature sensor 26 mounted on a general engine control system, it is necessary to newly mount a hydraulic pressure sensor and an oil temperature sensor. In addition, the demand for cost reduction, which is an important technical issue in recent years, can also be satisfied.

  In the first embodiment, the integrated value T of the deviation between the target cam shaft phase and the actual cam shaft phase is compared with the abnormality determination value to determine whether the lock mechanism 45 is abnormal. The presence / absence of an abnormality in the lock mechanism 45 may be determined by comparing the time during which the deviation between the phase and the actual camshaft phase is equal to or greater than a predetermined value with an abnormality determination value.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, the ECU 50 executes an abnormality diagnosis routine shown in FIG. 4 to be described later, and when it is determined that the low hydraulic pressure state where the cam shaft phase cannot be normally controlled is determined, the locus length Ltg of the target cam shaft phase. (The integrated value of the change amount) and the trajectory length L of the actual camshaft phase are obtained, and the trajectory length Ltg of the target camshaft phase and the trajectory length L of the actual camshaft phase are compared to determine whether the lock mechanism 45 is abnormal. The presence or absence is determined.

  When an abnormality occurs in which the lock of the lock mechanism 45 is automatically released and the actual cam shaft phase fluctuates, the trajectory length L of the actual cam shaft phase becomes larger than the trajectory length Ltg of the target cam shaft phase. Therefore, if the locus length Ltg of the target cam shaft phase is compared with the locus length L of the actual cam shaft phase, it is possible to accurately determine whether or not the lock mechanism 45 is abnormal.

  In the abnormality diagnosis routine shown in FIG. 4, in step 201, it is determined whether or not the low hydraulic pressure state in which the camshaft phase cannot be controlled normally is determined in the same manner as in the first embodiment, and is determined to be in the low hydraulic pressure state. In this case, the process proceeds to step 202, and an execution time counter that measures the execution time of the process of calculating the locus length Ltg of the target cam shaft phase and the locus length L of the actual cam shaft phase is counted up.

  Thereafter, the process proceeds to step 203, where the difference between the current value and the previous value of the actual cam shaft phase is obtained by calculating the difference between the current value and the previous value of the target cam shaft phase. To calculate the actual camshaft phase change amount.

  Thereafter, the process proceeds to step 204 where the current cam axis phase change amount is added to the previous target cam axis phase path length Ltg (n-1) to obtain the target cam axis phase path length Ltg (n). At the same time, the actual cam shaft phase trajectory length L (n) is updated by adding the actual cam shaft phase change amount to the previous actual cam shaft phase trajectory length L (n-1).

  Thereafter, when it is determined in step 201 that the hydraulic pressure state is not low, the routine proceeds to step 205 where the execution time of the process of calculating the locus length Ltg of the target cam shaft phase and the locus length L of the actual cam shaft phase is predetermined. If it is determined whether or not the execution time is equal to or longer than the predetermined time, it is determined that the abnormality diagnosis accuracy of the lock mechanism 45 can be ensured, and the process proceeds to step 206 to execute the target camshaft phase. It is determined whether or not the absolute value of the difference between the trajectory length Ltg of the actual camshaft and the trajectory length L of the actual camshaft phase is equal to or greater than the abnormality determination value.

  If it is determined in step 206 that the absolute value of the difference between the trajectory length Ltg of the target camshaft phase and the trajectory length L of the actual camshaft phase is greater than or equal to the abnormality determination value, the process proceeds to step 207 and the lock mechanism It is determined that there is an abnormality 45 (an abnormality has occurred in which the lock mechanism 45 is unlocked in a low hydraulic pressure state), the abnormality flag is set to ON, and processing at the time of abnormality determination is executed.

  On the other hand, if it is determined in step 206 that the absolute value of the difference between the locus length Ltg of the target cam shaft phase and the locus length L of the actual cam shaft phase is smaller than the abnormality determination value, step 208 is performed. Then, it is determined that there is no abnormality (normal) in the lock mechanism 45, and the abnormality flag is kept OFF.

  In the second embodiment described above, when the camshaft phase is in a low hydraulic pressure state where the camshaft phase cannot be controlled normally, if the abnormality of the lock mechanism 45 being unlocked occurs and the actual camshaft phase changes, the actual camshaft phase Paying attention to the fact that the trajectory length L of the target camshaft phase is larger than the trajectory length Ltg of the target camshaft phase, when it is determined that the hydraulic pressure state is low, the trajectory length Ltg of the target camshaft phase and the actual camshaft phase The trajectory length L is obtained, and the absolute value of the difference between the trajectory length Ltg of the target cam shaft phase and the trajectory length L of the actual cam shaft phase is compared with the abnormality determination value to determine whether the lock mechanism 45 is abnormal. Since it did in this way, when the abnormality which the lock | rock of the locking mechanism 45 self-releases in the low hydraulic pressure state generate | occur | produces, the abnormality can be detected.

  In the second embodiment, the absolute value of the difference between the trajectory length Ltg of the target cam shaft phase and the trajectory length L of the actual cam shaft phase is compared with the abnormality determination value to determine whether or not the lock mechanism 45 is abnormal. However, an abnormality determination value corresponding to the locus length Ltg of the target camshaft phase is set, and the locus length L of the actual camshaft phase is compared with the abnormality determination value to determine whether or not the lock mechanism 45 is abnormal. Anyway.

  In the first and second embodiments, the low hydraulic pressure state is determined based on the cooling water temperature detected by the cooling water temperature sensor 26. However, the oil temperature for detecting the oil temperature of the hydraulic oil in the variable valve timing device 34 is determined. When the present invention is applied to a system including a sensor, the hydraulic pressure is a predetermined lower limit hydraulic pressure (a hydraulic pressure capable of normally controlling the camshaft phase) depending on whether or not the oil temperature detected by the oil temperature sensor is lower than a predetermined value. It may be determined whether it is in a low hydraulic pressure state by estimating whether it is lower than the lower limit value of the range. In general, when the oil temperature decreases, the hydraulic oil viscosity increases and the hydraulic pressure supplied to the variable valve timing device 34 decreases. Therefore, the oil temperature is a parameter for evaluating the hydraulic pressure. Therefore, if it is determined whether or not the oil temperature detected by the oil temperature sensor is lower than the predetermined value, it is accurately estimated whether or not the oil pressure is lower than the predetermined lower limit value. Can be determined.

  Alternatively, the low oil pressure state determination time is set according to the oil temperature detected by the oil temperature sensor (or the low oil pressure state determination time is set in consideration of both the oil temperature and the cooling water temperature), and the elapsed time after starting the engine Whether or not the low hydraulic pressure state is set may be determined based on whether or not the time is within the low hydraulic pressure state determination time.

  In addition, when the present invention is applied to a system including a hydraulic pressure sensor that detects the hydraulic pressure of the hydraulic oil of the variable valve timing device 34, the low pressure depends on whether the hydraulic pressure detected by the hydraulic pressure sensor is lower than a predetermined lower limit hydraulic pressure. You may make it determine whether it is a hydraulic state. In this way, it is possible to accurately determine whether or not the hydraulic pressure state is low.

  In the first and second embodiments, the lock mechanism 45 including the lock pin and the lock hole is used as the phase maintaining mechanism for maintaining the camshaft phase at a predetermined position in the low hydraulic pressure state. However, the configuration of the phase maintaining mechanism may be changed as appropriate.

  Further, the scope of application of the present invention is not limited to a system including a variable valve timing device that changes the valve timing of the intake valve, and the present invention is applied to a system including a variable valve timing device that changes the valve timing of the exhaust valve. It may be applied.

  In addition, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, but includes an in-cylinder injection type engine, and both an intake port injection fuel injection valve and an in-cylinder injection fuel injection valve. It can also be applied to dual-injection engines.

It is a schematic block diagram of the whole engine control system in Example 1 of this invention. It is a schematic block diagram of a variable valve timing control system. 4 is a flowchart for explaining a flow of processing of an abnormality diagnosis routine according to the first embodiment. 6 is a flowchart for explaining a flow of processing of an abnormality diagnosis routine of a second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 28 ... Crankshaft, 32 ... Intake side camshaft, 34 ... Variable valve Timing device, 35 ... intake valve, 42 ... oil pump, 44 ... hydraulic control valve, 45 ... lock mechanism (phase maintaining mechanism), 50 ... ECU (low hydraulic pressure determination means, abnormality diagnosis means)

Claims (7)

A hydraulically driven variable valve timing device that changes the 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”), and at least the camshaft phase that cannot be normally controlled In a variable valve timing control system abnormality diagnosis device comprising a phase maintaining mechanism for maintaining the camshaft phase in a predetermined position when in a hydraulic state,
Low oil pressure state determining means for determining whether or not the low oil pressure state;
An abnormality diagnosing unit for determining whether the phase maintaining mechanism is abnormal based on a target cam shaft phase and an actual cam shaft phase when the low hydraulic pressure state determining unit determines that the low hydraulic pressure state is established. An abnormality diagnosis device for a variable valve timing control system, characterized in that: A hydraulic sensor that detects the hydraulic pressure of the hydraulic oil of the variable valve timing device;
The abnormality diagnosis device for a variable valve timing control system according to claim 1, wherein the low hydraulic pressure state determination means determines whether or not the low hydraulic pressure state is based on an output of the hydraulic pressure sensor. An oil temperature sensor for detecting the oil temperature of the hydraulic oil of the variable valve timing device;
The abnormality diagnosis device for a variable valve timing control system according to claim 1, wherein the low hydraulic pressure state determination means determines whether or not the low hydraulic pressure state is based on an output of the oil temperature sensor. A cooling water temperature sensor for detecting a cooling water temperature of the internal combustion engine;
The abnormality diagnosis device for a variable valve timing control system according to claim 1, wherein the low hydraulic pressure state determining means determines whether or not the low hydraulic pressure state is based on an output of the cooling water temperature sensor. A cooling water temperature sensor for detecting the cooling water temperature of the internal combustion engine and / or an oil temperature sensor for detecting the oil temperature of the hydraulic oil of the variable valve timing device;
The low hydraulic pressure determination means sets a low hydraulic pressure determination time according to the cooling water temperature detected by the cooling water temperature sensor and / or the oil temperature detected by the oil temperature sensor when the internal combustion engine is started. The abnormality diagnosis of the variable valve timing control system according to claim 1, wherein whether or not the low hydraulic pressure state is reached is determined by whether or not an elapsed time after starting is within the low hydraulic pressure state determination time. apparatus.   The abnormality diagnosis unit includes a unit that determines whether there is an abnormality in the phase maintaining mechanism using a deviation between the target cam shaft phase and the actual cam shaft phase or an integrated value of the deviation. The abnormality diagnosis device for a variable valve timing control system according to any one of 1 to 5.   The abnormality diagnosis unit includes a unit that determines whether or not the phase maintaining mechanism is abnormal by using a trajectory length of the target cam shaft phase and a trajectory length of the actual cam shaft phase. The abnormality diagnosis device for a variable valve timing control system according to any one of claims 6 to 10.

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