JP2002371812A - Variable valve timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a non-normal operating state of a variable valve timing device by leakage of oil from being erroneously decided as an abnormality of the variable valve timing device. SOLUTION: A delay angle control is performed for a valve opening timing of an intake valve to a target valve opening position for early warming of a catalyst during early warming control of the catalyst just after completing a starting, and whether or not a deviation of the target valve opening position and an actual valve opening position is larger than abnormality decision value is decided. Even if the deviation of the target valve opening position and the actual valve opening position is decided to be larger than the abnormality decision value before lapsed time after the starting reaches prescribed time KT required for filling hydraulic pressure into the variable valve timing device, the variable valve timing device is not decided as an abnormality and is decided as a temporary abnormality. After the variable valve timing device is decided as the temporary abnormality, the target valve opening position of the intake valve is changed to timing approaching to the present actual valve opening position by a small amount. When a deviation of the target valve opening position after the change and the actual valve opening position becomes below an abnormal decision value, the target valve opening position after the change is gradually returned up to a normal target valve opening position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a function of judging the presence or absence of an abnormality in a variable valve timing device based on the operating state of a variable valve timing device that varies the valve timing of an intake valve or an exhaust valve of an internal combustion engine by hydraulic pressure. The present invention relates to a variable valve timing control device for an internal combustion engine provided with:

[0002]

2. Description of the Related Art In recent years, an internal combustion engine mounted on a vehicle employs a variable valve timing device for varying the valve timing of an intake valve or an exhaust valve for the purpose of improving output, reducing fuel consumption, and reducing exhaust emissions. Is increasing. Generally, since the variable valve timing device is driven by the pressure (oil pressure) of oil discharged from an oil pump driven by an engine, the variable valve timing device is driven by a decrease in oil pressure due to a decrease in engine speed (oil pump speed). The operation delay time of the variable valve timing device may increase.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 7-127407, when the oil pressure discharged from the oil pump is equal to or less than a predetermined value, abnormality determination of the variable valve timing device is prohibited and the oil pressure discharged from the oil pump is reduced. It has been proposed to prevent an erroneous determination of an operation delay of the variable valve timing device from being an abnormality of the variable valve timing device.

[0004]

By the way, in order to cope with increasingly strict exhaust gas regulations in the future, the valve timing of the intake valve is retarded from the time of early catalyst warm-up control immediately after starting to reduce exhaust emissions. It has been proposed to. However, after the engine has been stopped for a long time or after the oil has been changed, the oil in the hydraulic circuit of the variable valve timing device may have leaked. When the engine is started in such a state in which the oil is drained, the oil discharged from the oil pump is filled in the hydraulic circuit of the variable valve timing device, and it takes some time until the hydraulic pressure of the hydraulic circuit rises to an appropriate range. It takes time. For this reason, even if an attempt is made to variably control the valve timing immediately after the start is completed, the variable valve timing device may not operate normally due to insufficient hydraulic pressure.

In such a case, in the technique disclosed in the above publication, the abnormality determination of the variable valve timing device is prohibited until the discharge oil pressure of the oil pump exceeds a predetermined value after the engine is started. After crossing,
Since the oil pressure is supplied to the oil pressure circuit of the variable valve timing device and the oil pressure of the oil pressure circuit rises to an appropriate range, there is a time delay. When the prohibition of the abnormality determination is released at a point in time when the predetermined value is exceeded, the state in which the variable valve timing device does not operate normally due to oil loss, even though the variable valve timing device itself is normal, is regarded as a variable valve timing device abnormality. There is a possibility of making an erroneous determination.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to erroneously determine that a state in which a variable valve timing device does not operate normally due to oil loss is an abnormality of the variable valve timing device. It is an object of the present invention to provide a variable valve timing control device for an internal combustion engine, which can be prevented beforehand and can improve the reliability of abnormality determination.

[0007]

According to a first aspect of the present invention, there is provided a variable valve timing control apparatus for an internal combustion engine according to the present invention. Until the hydraulic filling completion estimation condition that can be estimated to have risen to the appropriate range is satisfied, it is determined that the variable valve timing device is not abnormal. With this configuration, even if the variable valve timing device is started in a state where the oil is drained, the variable valve timing device is controlled until the hydraulic circuit is filled with oil and the hydraulic pressure of the hydraulic circuit rises to an appropriate range. Even if the timing device does not operate normally, it is not determined that the variable valve timing device is abnormal. As a result, it is possible to prevent a state in which the variable valve timing device does not operate normally due to oil loss, even though the variable valve timing device itself is normal, from being erroneously determined as an abnormality of the variable valve timing device.

In this case, various conditions are conceivable for the hydraulic pressure completion estimation condition, but the hydraulic pressure completion estimation condition is determined when the elapsed time after starting the engine is equal to or longer than a predetermined determination value. It is good to be established. That is, the time required for the hydraulic circuit of the variable valve timing device to be filled with oil and the hydraulic pressure of the hydraulic circuit to rise to an appropriate range is measured by a test or the like, and "predetermined judgment" is obtained from the measured data. By setting the “value”, it is possible to determine whether or not the hydraulic pressure of the hydraulic circuit of the variable valve timing device has risen to an appropriate range based on whether or not the elapsed time after starting the engine is equal to or more than a “predetermined determination value”. it can.

The condition for estimating the completion of the filling of the hydraulic pressure may be satisfied when the cumulative number of revolutions of the internal combustion engine after starting the engine becomes equal to or greater than a predetermined determination value. The cumulative number of revolutions of the internal combustion engine after the engine is started is proportional to the cumulative number of revolutions of the oil pump (cumulative oil discharge) after the engine is started, and as the cumulative number of revolutions of the oil pump (cumulative oil discharge) increases. There is a relation that the accumulated oil supply amount to the hydraulic circuit of the variable valve timing device increases. Therefore, when the cumulative number of revolutions of the internal combustion engine after the engine is started becomes equal to or more than a predetermined determination value, the oil filling amount of the hydraulic circuit of the variable valve timing device becomes equal to or more than the predetermined value, and the oil pressure of the hydraulic circuit rises to an appropriate range. It can be estimated that it has been done. Note that the cumulative number of revolutions of the internal combustion engine can be easily obtained by integrating the detection value of a sensor that detects the engine speed at every unit time.

The condition for estimating the completion of the hydraulic pressure filling may be established when the cumulative intake air amount after the start of the engine becomes equal to or greater than a predetermined determination value. Alternatively, the hydraulic pressure filling completion estimation condition may be satisfied when the cumulative intake pressure obtained by integrating the intake pressure in a predetermined cycle after the engine is started becomes equal to or greater than a predetermined determination value. good.
Since both the cumulative intake air amount and the cumulative intake pressure are parameters that reflect the cumulative rotational speed of the internal combustion engine after the engine is started and, consequently, the cumulative oil discharge amount of the oil pump after the engine is started, the cumulative intake air amount and the cumulative intake air If the atmospheric pressure is equal to or greater than the predetermined determination value, it can be estimated that the hydraulic pressure of the hydraulic circuit of the variable valve timing device has risen to an appropriate range.

Further, the condition for estimating the completion of the hydraulic pressure filling may be established when the cumulative oil discharge amount of the oil pump after the start of the engine becomes equal to or greater than a predetermined judgment value. As described above, the cumulative oil supply amount to the hydraulic circuit of the variable valve timing device increases with the increase in the cumulative oil discharge amount of the oil pump. It can be estimated that the hydraulic pressure of the hydraulic circuit of the variable valve timing device has risen to an appropriate range.

Further, the condition for estimating the completion of the hydraulic pressure filling may be established when the running distance after starting the engine has become equal to or greater than a predetermined judgment value. The mileage after starting the engine is a parameter that reflects the cumulative oil discharge amount of the oil pump after starting the engine, similarly to the cumulative rotation speed of the internal combustion engine after starting the engine. With the above, it can be estimated that the hydraulic pressure of the hydraulic circuit of the variable valve timing device has risen to an appropriate range.

[0013] By the way, as the stop time of the internal combustion engine becomes longer, the amount of oil that the variable valve timing device escapes increases. Further, the viscosity (fluidity) of the oil changes according to the cooling water temperature (oil temperature), and the oil filling property to the variable valve timing device changes.

In consideration of such circumstances, the predetermined judgment value used for judging the condition for estimating the completion of the hydraulic pressure filling is set to one of the stop time of the internal combustion engine, the cooling water temperature, and the intake air temperature. It is good to set according to the above conditions. With this configuration, the oil filling amount of the variable valve timing device and the oil filling property of the variable valve timing device change according to the stop time of the internal combustion engine and the cooling water temperature, and the hydraulic pressure filling completion estimation condition The predetermined determination value used for the determination can be set to a minimum necessary value, and it is possible to prevent the abnormality determination prohibition period after starting the engine from becoming unnecessarily long.

Further, when the deviation between the target valve timing and the actual valve timing is larger than the abnormality determination value before the condition for estimating the completion of the hydraulic pressure filling as in claim 9 is provisional, it means that there is a possibility of abnormality. It may be determined to be abnormal. In this way, even before the hydraulic pressure filling completion estimation condition is satisfied, it is possible to confirm whether the variable valve timing device is operating normally or whether there is a possibility of abnormality (temporary abnormality).

If it is determined that the variable valve timing device is provisionally abnormal due to oil loss before the hydraulic pressure filling completion estimation condition is satisfied, then when the variable valve timing device is filled with oil to some extent, There is a possibility that the actual valve timing may change drastically to near the target valve timing at once, whereby the air-fuel ratio may change suddenly and the exhaust emission and drivability may temporarily deteriorate.

As a countermeasure, when a temporary abnormality is determined before the condition for estimating completion of hydraulic pressure filling is satisfied, the deviation of the target valve timing from the actual valve timing does not fall below the abnormality determination value. The target valve timing is changed to a timing closer to the actual valve timing, and when the deviation between the changed target valve timing and the actual valve timing becomes equal to or less than the abnormality determination value, the target valve timing is gradually changed to the target valve timing according to the operating state. May be returned.

In this way, when it is determined that a temporary abnormality has occurred due to oil loss of the variable valve timing device, then when the variable valve timing device is filled with oil to some extent, first, the actual valve timing But,
It slightly changes toward the target valve timing changed to the vicinity. Then, when the deviation between the changed target valve timing and the actual valve timing is equal to or less than the abnormality determination value and the target valve timing is gradually changed to the target valve timing according to the operation state at that time, it is followed. Therefore, the actual valve timing changes gradually. As a result, when the variable valve timing device is filled with the oil to some extent, it is possible to prevent a sudden change in the actual valve timing, and to prevent deterioration of exhaust emission and drivability.

According to the present invention, the variable valve timing device is provided with a lock mechanism for locking the valve timing of the intake valve or the exhaust valve at a position suitable for starting when the engine is started. The present invention is preferably applied to a system in which the lock mechanism is unlocked immediately after the engine is started and the valve timing is changed. In a system in which the valve timing is changed immediately after the engine is started, if the engine is started in a state where the oil of the variable valve timing device is out of oil, the variable valve timing device does not operate normally when the oil pressure becomes insufficient immediately after the engine is started. The effect of applying is great.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
A description will be given based on FIGS. First, a schematic configuration of the entire system will be described with reference to FIG. The engine 11, which 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). Has become. However, the intake-side camshaft 16 is provided with a variable valve timing device 18 that varies the rotation phase of the intake-side camshaft 16 with respect to the crankshaft 12 to vary the valve timing of an intake valve (not shown). The oil in the oil pan 19 is supplied to the hydraulic circuit of the variable valve timing device 18 by an oil pump 20, and the oil pressure is supplied to the hydraulic control valve 2.
By controlling at 1 (OCV), the valve timing of the intake valve is controlled.

A cam angle sensor 22 for outputting a cam angle signal at a plurality of cam angles for cylinder discrimination is provided on the outer peripheral side of the intake side camshaft 16, and on the outer peripheral side of the crankshaft 12. A crank angle sensor 23 that outputs a crank angle signal for each predetermined crank angle is provided. The output signals of these cam angle sensor 22 and crank angle sensor 23 are
The ECU 24 calculates the actual valve timing (actual camshaft phase) of the intake valve and calculates the engine rotation from the frequency of the output pulse of the crank angle sensor 23 by an ECU 24. The speed is calculated.

Output signals of various sensors (throttle sensor, intake pipe pressure sensor, cooling water temperature sensor, etc.) not shown are also input to the ECU 24. The ECU 24 performs fuel injection control and ignition control based on these various input signals, performs variable valve timing control, and sets the actual valve timing of the intake valve (the actual camshaft phase of the intake camshaft 16) to the target valve. Timing (target camshaft phase)
The feedback control of the hydraulic control valve 21 of the variable valve timing device 18 is performed so as to make the same.

Next, the configuration of the variable valve timing device 18 with the intermediate lock mechanism will be described with reference to FIGS. As shown in FIG. 2, the variable valve timing device 1
8 is fixed to the sprocket 14 rotatably supported on the outer periphery of the intake camshaft 16 by bolts 26. As a result, the rotation of the crankshaft 12 is transmitted to the sprocket 14 via the timing chain 13.
The sprocket 14 and the housing 25 rotate in synchronization with the crankshaft 12. On the other hand, a rotor 27 is 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 fluid chambers 30 are formed inside the housing 25, and each fluid chamber 30 is
The vane 31 formed on the outer periphery of the rotor 27 divides the chamber into an advance chamber 32 and a retard chamber 33.

As shown in FIG. 2, when the oil pump 20 is driven by the power of the engine 11, the oil pumped from the oil pan 19 advances the intake camshaft 16 via the hydraulic control valve 21. It is supplied to the groove 34 and the retard groove 35. The 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. The hydraulic control valve 21 adjusts the position of the valve body to a position for supplying hydraulic pressure to the advance chamber 32, a position for supplying hydraulic pressure to the retard chamber 33, and to a position for supplying hydraulic pressure to both the advance chamber 32 and the retard chamber 33. Is switched to a position where no is supplied.

In a state where a hydraulic pressure equal to or more than a predetermined pressure 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 rotation of the housing 25 is performed by the rotor 27 via oil.
(The vane 31), and the intake-side camshaft 16 is driven to rotate integrally with the rotor 27. During operation of the engine, the hydraulic pressure in the advance chamber 32 and the retard chamber 33 is controlled by the hydraulic control valve 21 to relatively rotate the housing 25 and the rotor 27 (the vane 31), so that the intake side cam with respect to the crankshaft 12. The rotation timing (camshaft phase) of the shaft 16 is controlled to vary the valve timing of the intake valve.

A lock pin 38 for locking relative rotation between the housing 25 and the rotor 27 (vane 31) is accommodated in the vane 31, and the lock pin 38 is provided in a lock hole 39 provided in the housing 25. , The valve timing of the intake valve is locked at a substantially middle lock position of the adjustable range. This lock position is set to a position suitable for starting. The lock pin 38 is urged by a spring 40 in the lock direction (projection direction). A lock mechanism is composed of the lock pin 38, the lock hole 39, the spring 40, and the like.

While the engine is stopped, the lock pin 39 is held in the lock state by the spring 40 in the lock hole 39, and the valve timing of the intake valve is locked at the lock position. Accordingly, the engine is started in a locked state in which the lock pin 39 is fitted in the lock hole 39, and when the discharge pressure of the oil pump 30 increases to some extent, the lock pin 38 is pushed out of the lock hole 39 by hydraulic pressure. Move to the unlock position and lock pin 3
8 is released.

During operation of the engine, the lock pin 38 is operated by hydraulic pressure.
Is held at the unlocked position, and the housing 25 and the rotor 27 are held in a state where they can be relatively rotated (that is, a state where variable valve timing control is possible). The ECU 24
The hydraulic control valve 21 of the variable valve timing device 18 is set so that the actual valve timing of the intake valve (the actual camshaft phase of the intake camshaft 16) matches the target valve timing (the target camshaft phase of the intake camshaft 16). Perform feedback control. Thus, by controlling the hydraulic pressure of the advance chamber 32 and the retard chamber 33 to relatively rotate the housing 25 and the rotor 27, the camshaft phase is changed and the actual valve timing of the intake valve is set to the target valve timing. Match.

The ECU 24 has a ROM (storage medium).
By executing the valve timing control and abnormality determination program of FIGS. 3 and 4 stored in the ECU, during the early catalyst warm-up control immediately after the start, the valve opening timing of the intake valve is retarded to early catalyst warm-up control. It is determined whether the deviation between the target valve opening position and the actual valve opening position of the intake valve is greater than the abnormality determination value while improving the exhaust emission at the time. At this time, if the engine is started in a state in which the variable valve timing device 18 is out of oil, the variable valve timing device 1
It takes a while for the hydraulic pressure of the hydraulic circuit of No. 8 to rise to the appropriate range. Until then, the variable valve timing device 1
8 does not operate normally, the target valve opening position of the intake valve and the actual valve opening position until a predetermined hydraulic pressure filling completion estimation condition that can be estimated that the hydraulic pressure driving the variable valve timing device 18 has risen to an appropriate range is satisfied. Even if the positional deviation is larger than the abnormality determination value, it is not determined that the variable valve timing device 18 has an abnormality.

3 and 4 executed by the ECU 24.
The specific processing contents of the valve timing control and abnormality determination program will be described. This program is repeatedly executed at every predetermined time or every predetermined crank angle. When the present program is started, first, in step 101, it is determined whether or not the engine has been started, based on whether or not the engine rotational speed NE has exceeded a complete explosion determination value (for example, 400 rpm). If so, the program ends. Before the start is completed, the opening timing of the intake valve is locked at the valve opening position at the time of starting [for example, intake TDC (top dead center)] by the lock mechanism of the variable valve timing device 18.

Thereafter, when it is determined in step 101 that the start is completed, the routine proceeds to step 102, where it is determined whether or not the catalyst early warm-up execution condition is satisfied. Here, the catalyst early warm-up execution conditions include, for example, a cold start (the cooling water temperature at the time of starting is equal to or lower than a predetermined temperature), an idling operation state, and the like. If the early warm-up execution condition is satisfied, and if any one of the conditions is not satisfied, the catalyst early warm-up execution condition is not satisfied. If the catalyst early warm-up execution condition is not satisfied, the program is immediately terminated. In this case, the opening timing of the intake valve is controlled near the valve opening position (for example, intake TDC) at the start even after the start is completed by the normal control.

On the other hand, if the catalyst early warm-up execution condition is satisfied, it is determined that the catalyst (not shown) has not been activated, and the routine proceeds to step 103, where the ignition timing is retarded and the ignition timing is controlled. The ignition timing of the plug (not shown) is set to a target ignition timing for early warm-up of the catalyst [for example, ATDC 5 ° C. (5% after top dead center).
℃ A)]. As a result, the temperature of the exhaust gas is increased, and the warm-up (temperature rise) of the catalyst is promoted.

Thereafter, the routine proceeds to step 104, where the opening timing of the intake valve is adjusted to the target valve opening position for early catalyst warm-up [for example, ATDC 20 ° C. (upward) in order to reduce exhaust emission during early catalyst warm-up control. 20 ° C after dead center)).

Then, in the next step 105, it is determined whether or not the actual valve opening position of the intake valve has reached the target valve opening position for early catalyst warm-up. If the target valve opening position for warm-up has been reached, the process proceeds to the next step 106, in which it is determined whether or not the catalyst early warm-up termination condition has been satisfied, for example, whether or not the elapsed time after the start has reached a predetermined time or more. Determined by Until the catalyst early warm-up termination condition is satisfied, the valve opening timing of the intake valve is held at the target valve opening position for catalyst early warm-up (steps 104 to 104).
6).

Thereafter, when it is determined in step 106 that the condition for terminating the catalyst early warm-up is satisfied, the routine proceeds to step 10.
In step 7, the valve opening timing of the intake valve is gradually advanced from the target valve opening position for early catalyst warm-up to the normal target valve opening position. Then, in the next step 108, it is determined whether or not the actual valve opening position of the intake valve has reached the normal target valve opening position, whereby the actual valve opening position of the intake valve has become the normal target valve opening position. After confirming the above, exit this program.

On the other hand, if it is determined in step 105 that the actual valve opening position of the intake valve is not at the target valve opening position for early catalyst warm-up, the routine proceeds to step 109 in FIG. After calculating the deviation ΔVT between the target valve opening position and the actual valve opening position of the intake valve, the routine proceeds to step 110, where the deviation ΔVT between the target valve opening position and the actual valve opening position is smaller than the abnormality determination value (for example, 2 ° C.). It is determined whether it is larger.

If it is determined that the deviation ΔVT between the target valve opening position and the actual valve opening position is larger than the abnormality determination value before the hydraulic pressure filling completion estimation condition described later is satisfied, the cause is the oil in the variable valve timing device 18. Because there is a possibility that the variable valve timing device 18 is missing, the process proceeds to step 111 without determining that there is an abnormality in the variable valve timing device 18 and sets a temporary abnormality determination flag to “1” to determine a temporary abnormality. In this case, the catalyst early warm-up control (ignition timing retard control) may be stopped.

If it is determined that there is a temporary abnormality, step 112
Then, the target valve opening position of the intake valve is changed from the current actual valve opening position to a timing on the retard side by 4 ° C., for example. As a result, the deviation ΔVT between the target valve opening position of the intake valve and the current actual valve opening position is determined by an abnormality determination value (for example, 2 ° C.).
A) The actual valve opening position is approached within the range that does not become the following.

Thereafter, the routine proceeds to step 113, where it is determined whether or not the condition for estimating the completion of the hydraulic pressure filling has been satisfied, based on whether or not the elapsed time after the start has exceeded the predetermined determination time KT.
The predetermined determination time KT is set to a time (for example, 50 s) necessary for filling the oil pressure in the hydraulic circuit of the variable valve timing device 18 in a state where oil is removed from the start and for raising the oil pressure of the hydraulic circuit to an appropriate range. You.

If the condition for estimating the completion of hydraulic pressure filling is not satisfied, the routine returns to step 109 without determining that the variable valve timing device 18 is abnormal, and the deviation ΔVT between the changed target valve opening position and the actual valve opening position is determined. Is larger than the abnormality determination value, and if the deviation ΔVT between the changed target valve opening position and the actual valve opening position is larger than the abnormality determination value, the temporary abnormality determination flag is held at 1 and the intake air is held. The target valve opening position of the valve is maintained at the changed target valve opening position (step 1).
09-113).

If the deviation ΔVT between the changed target valve opening position and the actual valve opening position is equal to or less than the abnormality determination value before the hydraulic pressure filling completion estimation condition is satisfied, the routine proceeds from step 110 to step 115. Then, it is checked whether or not the temporary abnormality determination flag = 1, and if the temporary abnormality determination flag = 1, the process proceeds to step 116, where the temporary abnormality determination flag is reset to “0” to cancel the determination of the temporary abnormality. After that, the process proceeds to step 117, and after the changed target valve opening position is gradually returned to the target valve opening position for early catalyst warm-up (for example, ATDC 20 ° C.),
It returns to step 106 of FIG.

On the other hand, the deviation .DELTA.VT between the changed target valve opening position and the actual valve opening position does not become equal to or less than the abnormality determination value. If the filling completion estimation condition is satisfied, the routine proceeds to step 114, where an abnormality determination flag is set to "1" to determine that there is an abnormality in the variable valve timing device 18, and in the next step 118, the abnormality information is sent to the ECU 24.
And a warning lamp (not shown) is turned on to warn the driver, and the program is terminated. The processing of steps 109 to 117 plays a role corresponding to the abnormality determining means in the claims.

An execution example of the above-described valve timing control and abnormality determination of this embodiment will be described with reference to a time chart of FIG. The time chart of FIG. 5 shows that the engine 11
Shows an example of execution in the case where is started. Before starting,
The opening timing of the intake valve by the lock mechanism of the variable valve device 18 is set to the opening position at the start (for example, intake TDC).
Locked in. After the start-up is completed and the catalyst early warm-up execution condition is satisfied and the ignition timing is retarded, the opening timing of the intake valve is retarded to the target valve opening position for early catalyst warm-up (for example, ATDC 20 ° C.). Thus, exhaust emissions during early catalyst warm-up control are reduced.

When the engine is started in a state in which the variable valve timing device 18 is out of oil, the hydraulic pressure is not sufficiently supplied to the variable valve timing device 18 immediately after the start, and the variable valve timing device 18 does not operate normally. Although the deviation ΔVT between the target valve opening position and the actual valve opening position of the valve becomes larger than the abnormality determination value (for example, 2 ° C.), before the hydraulic pressure filling completion estimation condition is satisfied (the elapsed time after the start is longer than the predetermined determination time KT). Before reaching), it is determined that there is no abnormality in the variable valve timing device 18 but a temporary abnormality is determined (temporary abnormality determination flag = 1).

If it is determined that there is a tentative abnormality, the target valve opening position of the intake valve is changed from the current actual valve opening position to a timing on the retard side by, for example, 4 ° C. to approach the actual valve opening position. Thus, when the variable valve timing device 18 is filled with oil to some extent, the actual valve opening position of the intake valve slightly changes toward the target valve opening position changed to the vicinity thereof. When the deviation ΔVT between the changed target valve opening position and the actual valve opening position becomes equal to or smaller than the abnormality determination value, the provisional abnormality determination is released, and the changed target valve opening position is set to the target for early catalyst warm-up. Return gradually to the valve opening position. Accordingly, the actual valve opening position gradually changes following the change in the target valve opening position, and finally the actual valve opening position of the intake valve converges to the target valve opening position.

In the present embodiment described above, it is determined that there is no abnormality in the variable valve timing device 18 until the elapsed time after the start of the engine is equal to or longer than the predetermined determination time KT and the hydraulic pressure filling completion estimation condition is satisfied. Even if the engine is started in a state in which the variable valve timing device 18 is out of oil, the target valve opening of the intake valve is not performed until the hydraulic circuit of the variable valve timing device 18 is filled with oil and the hydraulic pressure of the hydraulic circuit rises to an appropriate range. Even if it is determined that the deviation ΔVT between the position and the actual valve opening position is larger than the abnormality determination value, it is not determined that the variable valve timing device 18 has an abnormality. Accordingly, it is possible to prevent a state in which the variable valve timing device 18 does not operate normally due to oil spillage as an abnormality of the variable valve timing device 18 before the variable valve timing device 18 itself is normal. Can be.

In this embodiment, if the deviation ΔVT between the target valve opening position and the actual valve opening position of the intake valve is larger than the abnormality determination value before the hydraulic pressure filling completion estimation condition is satisfied, it is determined that a temporary abnormality has occurred. Therefore, even before the hydraulic pressure filling completion estimation condition is satisfied, it is possible to confirm whether the variable valve timing device 18 is operating normally or whether there is a possibility of abnormality (temporary abnormality).

If it is determined that a temporary abnormality has occurred due to oil loss of the variable valve timing device 18 before the hydraulic pressure filling completion estimation condition is satisfied (the deviation ΔVT between the target valve opening position and the actual valve opening position of the intake valve is abnormal. If the variable valve timing device 18 is filled with oil to some extent thereafter, the actual opening position of the intake valve may greatly change to near the target opening position at a stretch. As a result, the air-fuel ratio may suddenly change, and the exhaust emission and drivability may temporarily deteriorate.

In this regard, in the present embodiment, when it is determined that a temporary abnormality has occurred before the hydraulic pressure filling completion estimation condition is satisfied, the deviation between the target valve opening position of the intake valve and the actual valve opening position is equal to or less than the abnormality determination value. When the deviation ΔVT between the changed target valve opening position and the actual valve opening position becomes equal to or less than the abnormality determination value, the changed target valve opening position is changed Since the catalyst is gradually returned to the target valve opening position for early warm-up of the catalyst, it is possible to prevent the actual valve opening position of the intake valve from suddenly changing greatly when the variable valve timing device 18 is filled with oil to some extent. As a result, it is possible to prevent deterioration of exhaust emission and drivability.

In this embodiment, when determining whether or not the hydraulic pressure filling completion estimation condition is satisfied based on whether or not the elapsed time after the start has become equal to or longer than a predetermined determination time KT, the predetermined determination time KT is fixed. The value (for example, 50 s) is used, but the viscosity (fluidity) of the oil changes according to the cooling water temperature (oil temperature), and the oil filling property to the variable valve timing device 18 changes. The predetermined determination time KT may be changed according to the cooling water temperature using a mathematical formula.

Alternatively, since the amount of oil escaping from the variable valve timing device 18 changes according to the engine stop time, a correction coefficient corresponding to the engine stop time is calculated by using a map of correction coefficients or a formula shown in FIG. The correction coefficient may be multiplied by the basic determination time to obtain a predetermined determination time KT (predetermined determination time KT = basic determination time × correction coefficient). Further, the final predetermined determination time KT may be obtained by multiplying the predetermined determination time changed according to the cooling water temperature by a correction coefficient corresponding to the engine stop time.

By setting the predetermined determination time KT in accordance with the engine stop time and the cooling water temperature, the amount of oil drainage of the variable valve timing device 18 and the variable valve timing can be set in accordance with the engine stop time and the cooling water temperature. The predetermined determination time KT can be set to a necessary minimum value in response to a change in the oil filling property of the device 18, and the abnormal determination prohibition period can be prevented from becoming unnecessarily long.

In the above-described embodiment, the condition for estimating the completion of the hydraulic pressure filling is satisfied when the elapsed time after the start is equal to or longer than the predetermined determination time KT. However, the cumulative engine speed ΣNE after the start is determined by the predetermined determination. The condition for estimating the completion of the hydraulic pressure filling may be established when the value becomes equal to or more than the value KNE. The cumulative engine speed ΣNE after the start is proportional to the cumulative speed (accumulated oil discharge amount) of the oil pump 20 after the start, and as the cumulative rotational speed (cumulative oil discharge amount) of the oil pump 20 increases, Variable valve timing device 18
There is a relationship that the accumulated oil supply amount to the hydraulic circuit increases.

Therefore, the cumulative engine speed after starting ΣN
If E is equal to or larger than the predetermined determination value KNE, it can be estimated that the oil filling amount of the hydraulic circuit of the variable valve timing device 18 has become equal to or larger than the predetermined value, and the oil pressure of the hydraulic circuit has increased to an appropriate range. Note that the cumulative engine speed 回 転 NE
Is obtained by integrating the engine rotation speed NE (rpm) detected by the crank angle sensor 23 for each unit time (for example, every one minute).

In this case, the predetermined criterion value KNE may be a fixed value (for example, 90000 rpm), but the predetermined criterion value KNE may be changed according to the cooling water temperature by using a table or a formula shown in FIG. Alternatively, the basic determination value is multiplied by a correction coefficient corresponding to the engine stop time to obtain a predetermined determination value KNE.
(Predetermined determination value KNE = correction coefficient × basic determination value) may be obtained. Further, the final predetermined determination value KNE may be obtained by multiplying the predetermined determination value changed according to the cooling water temperature by a correction coefficient according to the engine stop time.

Further, in a system provided with an air flow meter for detecting an intake air amount, the intake air amount is integrated at a predetermined cycle (for example, 1 s cycle) after starting to obtain an accumulated intake air amount. The hydraulic pressure filling completion estimation condition may be satisfied when the determination value KGA or more is reached. The cumulative intake air amount is a parameter that reflects the cumulative engine speed Σ NE after the start, and thus the cumulative oil discharge amount of the oil pump 20 after the start. Therefore, if the cumulative intake air amount is equal to or greater than the predetermined determination value KGA, the variable It can be estimated that the hydraulic pressure of the hydraulic circuit of the valve timing device 18 has risen to an appropriate range.

In this case, the predetermined determination value KGA may be a fixed value (for example, 900 g / s), but the predetermined determination value KGA may be changed according to the cooling water temperature by using a table or a formula shown in FIG. Alternatively, a predetermined determination value KGA (predetermined determination value KGA = correction coefficient × basic determination value) may be obtained by multiplying the basic determination value by a correction coefficient corresponding to the engine stop time. Further, the final predetermined determination value KGA may be obtained by multiplying the predetermined determination value changed according to the cooling water temperature by a correction coefficient according to the engine stop time.

In the system including the intake pressure sensor, the hydraulic pressure filling completion estimation condition is satisfied when the cumulative intake pressure obtained by accumulating the intake pressure in a predetermined cycle (for example, 1 s cycle) after starting becomes equal to or greater than a predetermined determination value KPM. You may do it.
The cumulative intake pressure is also a parameter that reflects the cumulative oil discharge amount of the oil pump 20 after the start, similarly to the cumulative intake air amount. Therefore, if the cumulative intake pressure becomes equal to or higher than the predetermined determination value KPM, the variable valve timing device 18 It can be estimated that the hydraulic pressure of the hydraulic circuit has risen to an appropriate range.

In this case, the predetermined criterion value KPM may be a fixed value (for example, 12000 mmHg), but the predetermined criterion value KPM may be changed according to the cooling water temperature by using a table or a mathematical formula shown in FIG. Alternatively, the basic determination value is multiplied by a correction coefficient corresponding to the engine stop time to obtain a predetermined determination value K.
PM (predetermined determination value KPM = correction coefficient × basic determination value) may be obtained. Further, the final predetermined determination value KPM may be obtained by multiplying a predetermined determination value changed according to the cooling water temperature by a correction coefficient according to the engine stop time.

Further, the condition for estimating the completion of hydraulic pressure filling may be established when the cumulative oil pump discharge amount after the start becomes equal to or greater than a predetermined determination value KOIL. As previously mentioned,
Since the cumulative oil supply amount to the hydraulic circuit of the variable valve timing device 18 increases with an increase in the cumulative oil discharge amount of the oil pump 20, if the cumulative oil pump discharge amount becomes equal to or more than the predetermined determination value KOIL, the variable valve timing It can be estimated that the hydraulic pressure of the hydraulic circuit of the device 18 has risen to an appropriate range.

In this case, the predetermined criterion value KOIL may be a fixed value (for example, 15 L), but the predetermined criterion value KOIL may be changed according to the cooling water temperature by using a table or a formula shown in FIG. Alternatively, the basic determination value is multiplied by a correction coefficient corresponding to the engine stop time to obtain a predetermined determination value KOIL
(Predetermined determination value KOIL = correction coefficient × basic determination value) may be obtained. Further, the final predetermined determination value KOIL may be obtained by multiplying a predetermined determination value changed according to the cooling water temperature by a correction coefficient according to the engine stop time.

The condition for estimating the completion of the filling of the hydraulic pressure may be established when the discharge pressure of the hydraulic control valve 21 becomes equal to or higher than a predetermined judgment value (for example, 20 kPa). Hydraulic control valve 2
1 increases the discharge pressure, the variable valve timing device 1
This is because there is a relationship that the hydraulic pressure of the hydraulic circuit 8 becomes higher.

Further, the hydraulic pressure filling completion estimation condition may be satisfied when the running distance after the start becomes equal to or more than a predetermined judgment value. The mileage after the start is a parameter that reflects the accumulated oil discharge amount of the oil pump 20 after the start, similarly to the accumulated engine speed after the start. Therefore, if the mileage after the start is equal to or more than a predetermined determination value, It can be estimated that the hydraulic pressure of the hydraulic circuit of the variable valve timing device 18 has risen to an appropriate range.

In the above-described embodiment, the present invention is applied to a system in which the valve timing of the intake valve is retarded at the time of early catalyst warm-up control immediately after the start of the engine. The present invention may be applied to a system in which the valve timing of the intake valve is retarded immediately after the start is completed regardless of whether or not the operation is performed. Of course, the present invention is applied to a system in which the valve timing of the intake valve is advanced after the start is completed. You may. Further, the present invention may be applied to a system for performing advance control or retard control of the valve timing of the exhaust valve immediately after the start is completed.

[Brief description of the drawings]

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 a variable valve timing device.

FIG. 3 is a flowchart showing a processing flow of a valve timing control and abnormality determination program (part 1);

FIG. 4 is a flowchart showing the flow of processing of a valve timing control and abnormality determination program (part 2).

FIG. 5 is a time chart showing an execution example of the embodiment;

FIG. 6 is a diagram illustrating an example of a table of a predetermined determination time KT according to a cooling water temperature;

FIG. 7 is a diagram showing an example of a map of a correction coefficient according to an engine stop time.

FIG. 8 is a diagram showing an example of a table of a predetermined determination value KPM according to a cooling water temperature;

FIG. 9 is a diagram showing an example of a table of a predetermined determination value KNE according to a cooling water temperature;

FIG. 10 is a diagram showing an example of a table of a predetermined determination value KGA according to a cooling water temperature;

FIG. 11 is a diagram showing an example of a table of a predetermined determination value KOIL according to a cooling water temperature;

[Explanation of symbols]

11 engine (internal combustion engine), 16 intake camshaft, 1
7: exhaust side camshaft, 18: variable valve timing device,
Reference Signs List 20 oil pump 21 hydraulic control valve 22 cam angle sensor 23 crank angle sensor 24 ECU (abnormality determination means) 25 housing 27 rotor 31
Vane, 32: advance chamber, 33: retard chamber, 38: lock pin (lock mechanism), 39: lock hole (lock mechanism), 4
0: Spring (lock mechanism).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G016 AA02 AA06 AA12 AA19 BA38 CA36 DA01 DA06 DA21 DA22 DA25 DA27 GA07 3G018 AA06 AB02 AB04 AB05 AB07 AB16 BA09 BA10 BA29 BA32 BA33 CA19 DA20 DA61 DA63 DA70 DA73 DA74 EA03 EA06 EA21 EA21 FA07 GA02 GA03 GA11 GA22 GA27 3G084 BA23 BA24 BA28 CA01 DA10 DA13 DA19 DA27 DA33 EB01 EB02 FA36 3G092 AA01 AA11 AB02 DA01 DA03 DA06 DA07 DA08 DA10 DF05 DF06 DF09 DG04 DG05 EA01 EA11 EA14 EA15 FA11 FB03

Claims (11)

[Claims] 1. A variable valve timing device for varying a valve timing of an intake valve or an exhaust valve of an internal combustion engine by hydraulic pressure, and determining whether there is an abnormality in the variable valve timing device based on an operation state of the variable valve timing device. In the variable valve timing control device for an internal combustion engine, comprising: an abnormality determination unit, the abnormality determination unit includes a hydraulic filling completion estimation condition that can estimate that a hydraulic pressure driving the variable valve timing device has increased to an appropriate range after the engine is started. A variable valve timing control device for an internal combustion engine, wherein the variable valve timing device is not determined to be abnormal until the condition is satisfied. 2. The variable valve timing control apparatus for an internal combustion engine according to claim 1, wherein the hydraulic pressure filling completion estimation condition is satisfied when an elapsed time after starting the engine is equal to or greater than a predetermined determination value. . 3. The variable internal combustion engine according to claim 1, wherein the hydraulic pressure filling completion estimation condition is satisfied when an accumulated rotation speed of the internal combustion engine after starting the engine becomes equal to or greater than a predetermined determination value. Valve timing control device. 4. The variable valve timing of an internal combustion engine according to claim 1, wherein the condition for estimating the completion of the hydraulic pressure filling is satisfied when an accumulated intake air amount after starting the engine becomes equal to or greater than a predetermined determination value. Control device. 5. The hydraulic pressure filling completion estimation condition is satisfied when an accumulated intake pressure obtained by integrating intake pressures in a predetermined cycle after starting the engine becomes equal to or greater than a predetermined determination value. 3. The variable valve timing control device for an internal combustion engine according to claim 1. 6. The internal combustion engine according to claim 1, wherein the hydraulic pressure filling completion estimation condition is satisfied when an accumulated oil discharge amount of the oil pump after starting the engine becomes equal to or greater than a predetermined determination value. Variable valve timing control device. 7. The variable valve timing control device for an internal combustion engine according to claim 1, wherein the condition for estimating completion of hydraulic pressure filling is satisfied when a traveling distance after starting the engine becomes equal to or greater than a predetermined determination value. . 8. The apparatus according to claim 2, wherein the abnormality determination unit sets the predetermined determination value in accordance with at least one of a stop time of an internal combustion engine, a cooling water temperature, and an intake air temperature. The variable valve timing control device for an internal combustion engine according to any one of claims 1 to 7. 9. The abnormal abnormality determining means may determine that there is a possibility of abnormality when a deviation between a target valve timing and an actual valve timing is larger than an abnormality determination value before the hydraulic pressure filling completion estimation condition is satisfied. The variable valve timing control device for an internal combustion engine according to claim 1, wherein the variable valve timing control device is configured to determine: 10. The abnormality judging means, when judging the provisional abnormality before the hydraulic pressure filling completion estimation condition is satisfied, sets a target valve timing within a range in which a deviation from an actual valve timing does not fall below the abnormality judgment value. The target valve timing is changed to a timing closer to the actual valve timing, and when the deviation between the changed target valve timing and the actual valve timing becomes equal to or less than the abnormality determination value, the target valve timing is gradually changed to the target valve timing according to the operation state. 10. The variable valve timing control device for an internal combustion engine according to claim 9, wherein the control is returned to. 11. The variable valve timing device according to claim 11,
A lock mechanism that locks a valve timing of an intake valve or an exhaust valve at a position suitable for starting when the engine is started, and releases the lock of the lock mechanism immediately after the engine starts to change the valve timing. Item 11. The variable valve timing control device for an internal combustion engine according to any one of Items 1 to 10.