JP2001182565A - Valve control device for combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve control device for an internal combustion engine provided with an oil temperature estimating means capable of relatively precisely estimating a temperature of hydraulic fluid of a hydraulic valve operating characteristic adjustable mechanism without using an expensive oil temperature sensor. SOLUTION: This valve control device for the internal combustion engine is provided with a hydraulic phase variable mechanism for changing rotational phase of an engine valve, a solenoid valve comprising a solenoid coil for controlling intake/discharge of the hydraulic fluid to/from the phase variable mechanism, and the oil temperature estimating means S15, S16, S17, S18 for estimating the temperature of the hydraulic fluid based on a value of a temperature index of the solenoid coil. The value of the temperature index can be obtained based on a duty ratio DT for setting an oil temperature of an exciting signal defining an operation amount of the solenoid valve and an amount of current I supplied to the solenoid coil during an output of the exciting signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve control apparatus for an internal combustion engine provided with a hydraulic valve operating characteristic variable mechanism for changing valve operating characteristics such as opening / closing timing of an intake valve or an exhaust valve as an engine valve. More specifically, the present invention relates to a valve train control device provided with oil temperature estimating means for estimating the temperature of hydraulic oil supplied to and discharged from a valve operating characteristic variable mechanism.

[0002]

2. Description of the Related Art Conventionally, a valve operating device for an internal combustion engine includes a valve, such as an opening / closing timing of an intake valve or an exhaust valve, a lift amount, and a valve opening period, from the viewpoint of improvement of engine output, fuel efficiency and exhaust emission. Some include a hydraulic valve operating characteristic variable mechanism whose operating characteristic is variable according to the operating state of the internal combustion engine.

[0003] Since this variable valve operating characteristic mechanism is driven by hydraulic oil supplied and discharged by a hydraulic oil control valve, its behavior greatly influences the oil temperature of the hydraulic oil (hereinafter simply referred to as "oil temperature"). receive. Therefore, in this type of variable valve operating characteristic mechanism, control is performed in consideration of the effect of the oil temperature.

For example, a valve timing control device for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. H11-2142 adjusts the rotation phase of a camshaft by the hydraulic pressure of hydraulic oil adjusted by a linear solenoid valve whose amount of current is controlled. A hydraulic valve timing mechanism for changing the rotation phase is provided, and the valve timing mechanism is configured such that the most advanced side of the rotation phase is limited by the stopper before the duty for controlling the amount of energization reaches 100%.

[0005] Immediately after the target value is switched to the most advanced angle side, the linear solenoid has a predetermined time until the actual rotational phase changes to the most advanced angle side (stopper position).
% Duty is given, and after the predetermined time elapses, the duty is reduced to a smaller value capable of holding the rotation phase on the most advanced side, thereby saving power consumption and suppressing a rise in coil temperature. It is. At this time, if the oil temperature is low, the time required to reach the most advanced side becomes longer. Therefore, the predetermined time is corrected by the oil temperature so that the predetermined time becomes an appropriate value. You.

[0006]

The provision of an oil temperature sensor for detecting the oil temperature increases the cost of an apparatus having a variable valve timing mechanism because the oil temperature sensor is relatively expensive. Become. Also, instead of providing an oil temperature sensor, it is conceivable to use a water temperature sensor for detecting the temperature of cooling water provided for another device, but between the oil temperature and the water temperature, Delays in heat transfer,
Due to differences in the specific heats of the two and the like, a shift may occur in the transition of the temperature change, and it cannot be said that there is always a strong correlation. Therefore, in the case of using the water temperature sensor instead of the oil temperature sensor, it has been difficult to obtain good control accuracy of the hydraulic valve timing variable mechanism.

[0007] The present invention has been made in view of such circumstances, and the temperature of hydraulic oil of a hydraulic valve operating characteristic variable mechanism can be relatively accurately measured without using an expensive oil temperature sensor. It is an object of the present invention to provide a valve operating control device for an internal combustion engine including an oil temperature estimating means that can be estimated.

[0008]

The invention according to claim 1 of the present application has a hydraulic valve operating characteristic variable mechanism for changing the operating characteristics of an engine valve, and an electromagnetic coil. Electromagnetic hydraulic oil control means for controlling the supply and discharge of hydraulic oil to and from the variable characteristic mechanism; control means for controlling the drive of the hydraulic oil control means; and controlling the temperature of the hydraulic oil based on a temperature index value of the electromagnetic coil. A valve operating device for an internal combustion engine, comprising: an oil temperature estimating means for estimating the oil temperature.

According to the first aspect of the present invention, the estimated oil temperature is obtained based on the temperature index value of the electromagnetic coil of the hydraulic oil control means for controlling the supply and discharge of the hydraulic oil to and from the hydraulic valve operating characteristic variable mechanism. Therefore, an expensive oil temperature sensor is not required, and the cost of the valve train control device can be reduced.

In addition, since the hydraulic oil control means is always in contact with the hydraulic oil at the time of supply and discharge, the hydraulic oil control means is directly affected by the oil temperature. It is strongly affected and has a strong correlation between the oil temperature and the temperature of the electromagnetic coil. Therefore, the estimated oil temperature obtained based on the temperature index value, which is a value related to the temperature of the electromagnetic coil, reflects the temperature transition of the oil temperature more accurately than the conventional cooling water temperature.

According to a second aspect of the present invention, in the valve operating control device for an internal combustion engine according to the first aspect, the temperature index value includes an energization signal output from the control means to the hydraulic oil control means, This is a value obtained based on the amount of current supplied to the electromagnetic coil while the signal is being output.

According to the second aspect of the invention, the temperature index value is supplied to the electromagnetic coil while the energization signal is being output and the energization signal for determining the operation amount of the driven hydraulic oil control means. It is obtained by using the current amount. The amount of current at this time depends on the electric resistance value of the electromagnetic coil, and since the electric resistance value is a function of the temperature of the electromagnetic coil, the value obtained based on the energization signal and the current amount is It serves as a temperature index value, and there is a strong correlation between the temperature index value and the oil temperature. Therefore, it is possible to accurately estimate the oil temperature based on the energization signal for driving the hydraulic oil control means and the amount of current having a clear correspondence with the temperature of the electromagnetic coil reflecting the oil temperature.

According to a third aspect of the present invention, in the valve operating control apparatus for an internal combustion engine according to the first or second aspect, the oil temperature estimating means includes a valve operating characteristic variable after completion of starting the internal combustion engine. The temperature is estimated during the operation prohibition time of the mechanism.

According to the third aspect of the invention, the oil temperature is estimated after the start of the internal combustion engine is completed, and after the operation of the stopped internal combustion engine is started, the valve operating characteristic variable mechanism is operated. Since it is executed during a period that does not lead to the operation, the oil temperature can be estimated without affecting the operation of the variable valve operation characteristic mechanism. In addition, the obtained estimated oil temperature can be used as an operation start condition of the variable valve operating characteristic mechanism, and the variable valve operating characteristic mechanism that reflects the oil temperature can be controlled from an early stage after the internal combustion engine is started. , Over a wide operating area of the internal combustion engine,
More precise control reflecting the oil temperature of the valve operating characteristic variable mechanism can be performed.

According to a fourth aspect of the present invention, in the valve control apparatus for an internal combustion engine according to any one of the first to third aspects, the temperature index value is determined by an ambient temperature of the internal combustion engine immediately before starting. It is the corrected value.

According to the present invention, the temperature index value is corrected by the ambient temperature of the internal combustion engine immediately before starting. This ambient temperature is maintained until the internal combustion engine,
Further, the state reflects the state where the electromagnetic coil of the hydraulic oil control means is placed, and has an effect on the temperature of the electromagnetic coil. The temperature of the electromagnetic coil immediately before the start of the internal combustion engine also affects the temperature of the electromagnetic coil placed under the influence of the oil temperature after the start of the internal combustion engine is completed. Therefore, a more accurate estimated oil temperature can be obtained by using the temperature index value that takes into account the ambient temperature immediately before the start of the internal combustion engine that affects the temperature index value of the electromagnetic coil.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, an internal combustion engine 1 is a spark ignition type 4 mounted on a vehicle.
This is a cylinder DOHC internal combustion engine, and each piston 2 is connected to a crankshaft 4 via a connecting rod 3. As shown in FIG. 1, a drive sprocket 5 provided at a shaft end of a crankshaft 4 and intake and exhaust cam sprockets provided at one shaft end of an intake camshaft 6 and an exhaust camshaft 7, respectively. 8 and 9 are connected via a timing chain 10, and both camshafts 6 and 7 are rotationally driven at a reduction ratio of 1/2 of the rotation of the crankshaft 4.

Each cylinder has two intake valves 13, which are engine valves driven by an intake cam 11 provided on the intake camshaft 6.
And two exhaust valves 14, which are engine valves driven by an exhaust cam 12 provided on the exhaust cam shaft 7.
Between the intake camshaft 6 and the intake valve 13, and between the exhaust camshaft 7 and the exhaust valve 14, the lift amounts and the valve opening periods of the valves 13 and 14 are set according to the rotation speed Ne of the internal combustion engine 1. A switching mechanism 15 for switching is provided. In the intake camshaft 6, the rotation end of the intake camshaft 6 with respect to the crankshaft 4 is steplessly advanced or retarded at the shaft end where the intake cam sprocket 8 is provided, so that the intake cam 11 A hydraulic phase variable mechanism 20, which is a valve operating characteristic variable mechanism for changing the opening / closing timing of the intake valve 13 by advancing or retarding the cam phase steplessly, is provided.

As shown in FIGS. 2 and 3, the variable phase mechanism 20 has a support hole 21a formed at the center of a substantially cylindrical boss member 21 coaxially with the shaft end of the intake camshaft 6. The boss member 21 and the intake camshaft 6 are fitted so as to be relatively non-rotatable by pins 22 and bolts 23. The intake cam sprocket 8 around which the timing chain 10 is wound is formed in a substantially cup shape having a circular concave portion 8a, and sprocket teeth 8b are formed on the outer periphery thereof. An annular housing 24 fitted into the concave portion 8a of the intake cam sprocket 8 and a plate 25 superposed in the axial direction thereof are connected to the intake cam sprocket 8 with four bolts 26 penetrating therethrough.

Therefore, the boss member 21 integral with the intake camshaft 6 is housed in a space surrounded by the intake cam sprocket 8, the housing 24 and the plate 25 so as to be relatively rotatable with respect to them. A lock pin 27 is slidably fitted in a pin hole 21c penetrating through the boss member 21 in the axial direction. The lock pin 27 is compressed by a spring 28 mounted between the plate 25 and the air intake. The cam sprocket 8 is urged in a direction to engage with a lock hole 8c formed in the cam sprocket 8.

Inside the housing 24, four fan-shaped concave portions 24a centered on the axis of the intake camshaft 6 are formed at 90 ° intervals, and four vanes projecting radially from the outer periphery of the boss member 21 are formed. 21b is fitted in the concave portion 24a so as to be relatively rotatable within a central angle range of 30 °. Four sealing members 29 provided at the tips of the four vanes 21b slidably abut the ceiling wall of the recess 24a, and four sealing members 30 provided on the inner peripheral surface of the housing 24 are bosses. An advancing chamber 31 and a retarding chamber 32 are defined on both sides of each vane 21b by slidably contacting the outer peripheral surface of the member 21.

Inside the intake camshaft 6, an advance oil passage 33 and a retard oil passage 34 are formed, and the advance oil passage 33 penetrates the boss member 21 in four radial directions. 4 via oilway 35
The retarding oil passages 34 communicate with the four retarding chambers 32 via four oil passages 36 penetrating through the boss member 21 in the radial direction. Lock pin 27
The lock hole 8c of the intake cam sprocket 8 to which the head of
Communicates with one of the advance chambers 31 via an oil passage (not shown).

When no hydraulic oil is supplied to the advance chamber 31, the head of the lock pin 27 fits into the lock hole 8c of the intake cam sprocket 8 by the elastic force of the spring 28, and is shown in FIG. Thus, the intake camshaft 6 is locked in the most retarded state in which the intake camshaft 6 is rotated counterclockwise relative to the intake cam sprocket 8. When the hydraulic pressure of the hydraulic oil supplied to the advance chamber 31 increases from this state, the lock pin 27 is pressed against the resilience of the spring 28 by the hydraulic pressure of the hydraulic oil supplied from the advance chamber 31 so that the intake cam sprocket 8 Of the intake cam sprocket 8, the vane 21b is pushed by the hydraulic pressure difference between the advance chamber 31 and the retard chamber 32, and the intake camshaft 6 rotates clockwise relative to the intake cam sprocket 8. As the phase of the intake cam 11 with respect to 4 advances, the valve opening timing and the valve closing timing of the intake valve 13 change to the advanced side. Therefore, the advance chamber
By controlling the supply and discharge of hydraulic oil to and from the retard chamber 32 and the hydraulic pressure of the hydraulic oil in both chambers 31 and 32, the intake valve is controlled.
13 opening and closing timing can be changed steplessly.

Next, with reference to FIG. 4, a description will be given of the hydraulic oil passage and the control system of the switching mechanism 15 and the variable phase mechanism 20. Oil pumped by an oil pump 40 serving as a hydraulic pressure source from an oil pan 41 via an oil passage 42 is used as lubricating oil around the crankshaft 4 of the internal combustion engine 1 and a valve operating mechanism. It is discharged to the oil passage 43 as hydraulic oil. An oil passage 44 branched from the oil passage 43 and communicating with the switching mechanism 15 has a hydraulic switching valve for switching the oil pressure of the oil passage 44 between high and low.
46 are provided. The oil passage 45 branched from the oil passage 43 and communicated with the variable phase mechanism 20 includes an advance chamber 31 and a retard chamber.
The linear solenoid valve 50 is a hydraulic oil control means for controlling the supply and discharge of hydraulic oil to and from the hydraulic oil in both chambers 31 and 32.
Is provided.

On the other hand, an electronic control unit 47 which is a control means for controlling the operation amount by driving the hydraulic switching valve 46 and the solenoid valve 50 has an intake camshaft sensor 16 for detecting the rotational position θI of the intake camshaft 6. (See FIG. 1), a TDC sensor that detects the top dead center θTD of the piston 2 based on an exhaust cam shaft sensor 17 (see FIG. 1) that detects the rotational position of the exhaust cam shaft 7,
A crankshaft sensor 18 (see FIG. 1) for detecting the rotational position θC of the crankshaft 4, an intake pressure sensor for detecting the intake pressure P, a cooling water temperature sensor for detecting the cooling water temperature TW, and a throttle opening for detecting the throttle opening ΔTH Signals from a sensor, a rotational speed sensor for detecting the rotational speed Ne of the internal combustion engine 1, an intake air temperature sensor for detecting the intake air temperature TA, and a current amount detecting sensor for detecting the amount of current I supplied to the solenoid valve 50 are input. Is done.

Further, the electronic control unit 47 has a target cam phase CM using the intake pressure P and the rotation speed Ne as parameters.
Various maps and tables used when controlling the hydraulic switching valve 46 and the solenoid valve 50 are stored. Here, the valve train control device includes the phase variable mechanism 2
0, an electromagnetic valve 50, a hydraulic switching valve 46, a switching mechanism 15, an electronic control unit 47, an oil pump 40, and oil passages 43, 44, 45.

On the other hand, as shown in FIG. 5, the solenoid valve 50 has a cylindrical sleeve 51, a spool 52 slidably fitted inside the sleeve 51, and a spool 52 fixed to the sleeve 51. And a spring 54 for urging the spool 52 toward the electromagnetic coil 53. The operation amount of the solenoid valve 50 is determined according to the current amount I to the electromagnetic coil 53 which is controlled based on the duty ratio based on the ON duty of the energization signal output from the electronic control unit 47. The spool 52 moves against the elasticity of the spring 54 according to the duty ratio,
Its axial position is steplessly changed.

The sleeve 51 has a central inflow port 51a.
And an advance port 51b and a retard port 51c located on both sides thereof, and a pair of drain ports 51d and 51e located on both sides of both ports 51b and 51c. on the other hand,
The spool 52 has a central groove 52a, a pair of lands 52b and 52c located on both sides thereof, and both lands 52b and 52c.
And a pair of grooves 52d and 52e located on both sides of are formed. The inflow port 51a is connected to the oil pump 40,
The advance port 51b is connected to the advance chamber 31 of the variable phase mechanism 20, and the retard port 51c is connected to the retard chamber 32 of the variable phase mechanism 20. When current is not supplied to the solenoid valve 50, the spool 52 is biased by the spring 54,
The inflow port 51a communicates with the retard port 51c and the advance port 51
b is in a state of communicating with the drain port 51d.

Next, the operation of the variable phase mechanism 20 for supplying and discharging hydraulic oil by the solenoid valve 50 will be described. When the internal combustion engine 1 is stopped, the variable phase mechanism 20 is in a state where the retard chamber 32 has a maximum volume and the advance chamber 31 has a zero volume.
The lock pin 27 fits into the lock hole 8c of the intake cam sprocket 8, and is maintained at the most retarded state. When the internal combustion engine 1 starts, the oil pump 40 operates, and when the hydraulic pressure of the hydraulic oil supplied to the advance chamber 31 via the solenoid valve 50 exceeds a predetermined value, the lock pin 27 is disengaged from the lock hole 8c by the hydraulic pressure. Thus, the variable valve phase mechanism 20 becomes operable.

In this state, when the duty ratio of the energizing signal is increased from the set value of the neutral position, for example, 50%, the spool 52 moves to the left side of the neutral position against the spring 54 in FIG. The inflow port 51a connected to the pump 40 communicates with the advance port 51b via the groove 52a, and the retard port 51c communicates with the drain port 51e via the groove 52e. As a result, the phase variable mechanism 2
Hydraulic oil is supplied to the 0 advance chamber 31 and the hydraulic pressure rises, and the hydraulic oil is discharged from the retard chamber 32 and the hydraulic pressure decreases.
The intake camshaft 6 with respect to the intake cam sprocket 8
Are relatively rotated clockwise, and the cam phase of the intake camshaft 6 continuously changes to the advance side. When the target cam phase is obtained, the duty ratio of the energization signal is set to about 5
The spool 52 of the solenoid valve 50 is set to the neutral position shown in FIG. 5, that is, the inflow port 51a is connected to the pair of lands 52b and 52c.
The intake cam sprocket 8 and the intake camshaft 6 are closed by stopping at the positions where the retard port 51c and the advance port 51b are closed by the lands 52b and 52c, respectively.
And the cam phase can be kept constant.

In order to continuously change the cam phase of the intake camshaft 6 to the retard side, the duty ratio of the energization signal is reduced from 50%, the spool 52 is moved rightward from the neutral position, and connected to the oil pump 40. The inflow port 51a communicates with the retard port 51c via the groove 52a, and the advance port 51b
Through the groove 52d to the drain port 51d,
Hydraulic oil may be supplied to the retard chamber 32 of the variable phase mechanism 20 to increase the hydraulic pressure, and hydraulic oil may be discharged from the advance chamber 31 to reduce the hydraulic pressure. Then, when the target phase is obtained, the duty ratio of the energization signal is set to about 5
By setting the spool 52 to 0% and stopping the spool 52 at the neutral position shown in FIG. 5, the inflow port 51a, the retard port 51c, and the advance port 51b can be closed, and the cam phase can be kept constant.

Since the variable phase mechanism 20 is driven by the hydraulic oil, its behavior is affected by the oil temperature (temperature of the hydraulic oil). For example, since the viscosity of the hydraulic oil changes depending on the oil temperature, the hydraulic oil is applied to both the chambers 31 and 32 in order to form a hydraulic pressure difference between the advance chamber 31 and the retard chamber 32 of the variable phase mechanism 20. When the actual cam phase of the intake camshaft 6 approaches the target cam phase, the response is affected by the viscosity of the hydraulic oil. Therefore, it is preferable from the viewpoint of convergence or follow-up to the target value to change the operation of the phase variable mechanism 20 according to the oil temperature in the control gain in the feedback control described later. In addition, it is preferable to determine the operation mode of the phase variable mechanism 20 and to grasp the operation state in consideration of the oil temperature.

Accordingly, here, since the oil temperature is provided in the oil passage 45 without using an expensive oil temperature sensor, the electromagnetic valve 50 of the solenoid valve 50 which is under the influence of the oil temperature and reflects the oil temperature is used. The oil temperature is estimated based on the temperature index value of the coil 53.

The procedure for estimating the oil temperature will be described below with reference to FIGS. The flowchart in FIG. 6 shows an oil temperature estimation duty ratio output routine for outputting an oil temperature estimation energization signal to the solenoid valve 50 immediately after the start of the internal combustion engine 1 (cranking end). Is executed in the electronic control unit 47 every predetermined time.

First, in step S1, the hydraulic pressure of the working oil reaching the variable phase mechanism 20 after the start of the internal combustion engine 1 is completed is set, and the operation of the variable phase mechanism 20 is prohibited until the preparation for operation is completed. It is determined whether or not the operation inhibition timer TS to which the time (for example, 3 seconds) has been set has timed out. If the time has not elapsed, the phase is changed by the operating oil supplied to the retard chamber 32 in step S2. Whether the zero point learning inhibition time t1 (for example, 2 seconds) for inhibiting the learning of the zero point of the variable phase mechanism 20 performed after the start is completed has elapsed until the mechanism 20 reliably occupies the position where the most retarded state is reached. Is determined, and if not, step S
Step 3 when the delay time t2 (for example, 0.1 seconds) for avoiding the detection of the current amount I to the electromagnetic coil 53, which will be described later, immediately after the completion of the start in which the state of the hydraulic oil is unstable has elapsed. Proceed to S4.

In step S4, the set value of the duty ratio of the energization signal is set as the oil temperature estimation duty ratio DT in order to drive the solenoid valve 50 to estimate the oil temperature.
The energization signal having this temperature measurement duty ratio DT is
It is output from the electronic control unit 47 as an energization signal for oil temperature estimation to the solenoid valve 50. At this time, while the energization signal of the oil temperature estimation duty ratio DT is being output, the electromagnetic coil 53
, And the current amount I is detected by the current amount detection sensor. The means for outputting the energization signal of the oil temperature estimation duty ratio DT set in step S4 is the oil temperature estimation energization signal output means.

The set value is, for example, a duty ratio of 55%.
From the oil passage 45 to the advance chamber 31 of the phase variable mechanism 20 through the oil passage 45, through a spool 52 made of a heat conductive material in contact with the flowing hydraulic oil at that time. ,
The temperature of the electromagnetic coil 53 of the solenoid valve 50 further reflects the oil temperature. On the other hand, with this set value,
The hydraulic pressure is such that the boss member 21 does not rotate relative to the housing 24, that is, the lock pin 27 does not separate from the lock hole 8c in the advance chamber 31, and the cam phase does not change. A hydraulic fluid is provided. Then, in step S5, the oil temperature estimation execution flag FT is set to "1", and the routine ends.

On the other hand, in step S1, the operation inhibition timer TS
If the time has elapsed, the process proceeds to step S6, in which the solenoid valve is moved to bring the actual cam phase closer to the target cam phase set with the intake pressure P and the rotation speed Ne as parameters.
A normal duty ratio calculation routine, which is another routine for calculating the duty ratio of the energization signal output to 50, is executed.

In step S7, the phase variable mechanism 20
After the operation prohibition is released, an oil temperature estimation execution condition determination routine, which is another routine for determining whether or not a condition for enabling oil temperature estimation, is satisfied. In this routine, if the feedback control of the variable phase mechanism 20 is permitted, the current amount I for maintaining the neutral position of the solenoid valve 50 is set to a predetermined value in order for the variable phase mechanism 20 to maintain the target cam phase. It is determined whether the current cam phase is within a predetermined range, the actual cam phase is within a predetermined range in the vicinity of the target cam phase, and the fluctuation of the rotation speed Ne is within a predetermined range. When this is done, the oil temperature estimation execution flag FT is set to "1", otherwise the oil temperature estimation execution flag FT is set to "0". Thus, the oil temperature can be estimated even when the feedback control of the variable phase mechanism 20 is being performed.

Note that in both of these separate routines,
When the feedback control of the phase variable mechanism 20 is not permitted, the substantial processing of those routines is not performed,
The oil temperature estimation execution flag FT is set to “0”. Therefore, when the zero point learning inhibition time t1 has elapsed in step S2, and when the delay time t2 has not elapsed in step S3, the process proceeds to step S6 and step S7. At this time, the feedback control of the phase variable mechanism 20 is permitted. Therefore, the oil temperature estimation execution flag FT is set to “0” without executing the processes of the duty ratio calculation and the oil temperature estimation execution condition determination.

In the process from step S2 to step S4, the oil temperature estimation duty ratio is output during the operation inhibition time of the variable phase mechanism 20 and during the zero point learning inhibition time to output the oil temperature estimation duty ratio. This is because the oil temperature can be estimated without affecting the operation of the variable phase mechanism 20. In addition, by estimating the oil temperature at an early stage after the start of the internal combustion engine 1 in a state where the operating oil is supplied to the variable phase mechanism 20 via the solenoid valve 50, the obtained estimated oil temperature is used as the variable phase mechanism. Over a wide operating range of the internal combustion engine, such as being used for the operation start condition of 20, or being able to control the phase variable mechanism 20 reflecting the oil temperature from an early stage after the start of the internal combustion engine,
This is because more accurate control that reflects the oil temperature of the phase variable mechanism 20 can be performed.

Next, a procedure for calculating the estimated oil temperature using the oil temperature estimation duty ratio DT obtained in the above-described oil temperature estimation duty ratio output routine and the detected current amount I to the electromagnetic coil 53. Will be described. The flowchart of FIG. 7 shows an estimated oil temperature calculation routine, which is executed by the electronic control unit 47 at predetermined time intervals.

First, in step S11, it is determined whether or not a set time t3 (for example, 5 seconds) has elapsed from immediately after the start which may have a relatively large fluctuation in the oil temperature, and if the set time t3 has not elapsed. Sets the set value KS, which is a coefficient immediately after the start is completed, to the smoothing coefficient CT in step S12, and proceeds to step S14. If the set time t3 has elapsed, the set value KN, which is a normal time coefficient, is set to the smoothing coefficient CT in step S13, and the flow advances to step S14.

Here, the smoothing coefficient CT is used for calculating the smoothing of the estimated oil temperature in step S18, which will be described later, in order to reduce the influence of a large fluctuation in the actual oil temperature on the estimated oil temperature. Since the state of the hydraulic oil immediately after the start is not stable, including the oil temperature, as compared with the normal state, the set value KS is set to be larger than the set value KN (for example, three times the set value KN). You.

In step S14, the oil temperature estimation execution flag F
When the oil temperature estimation execution flag FT is “1”, the process proceeds to step S15, and until immediately before the start of the internal combustion engine 1,
In consideration of the state where the internal combustion engine 1 and the electromagnetic coil 53 of the electromagnetic valve 50 attached to the internal combustion engine 1 are placed (soak state), a process for more accurately estimating the oil temperature is performed. That is, the ambient temperature of the internal combustion engine 1 before the start of the start reflects the state in which the internal combustion engine 1 was placed immediately before the start, and affects the temperature of the electromagnetic coil 53. The temperature of the electromagnetic coil 53 immediately before the start of the internal combustion engine 1 depends on the temperature of the electromagnetic coil 53 that is affected by the oil temperature after the internal combustion engine 1 is started and the oil pump 40 is operated.
Affects temperature of 53.

In order to reflect the temperature of the electromagnetic coil 53 immediately before the start to the estimated oil temperature, the intake air temperature TA as the ambient temperature of the internal combustion engine 1 is detected by the intake air temperature sensor immediately after the start of the internal combustion engine 1, and As shown in FIG. 8, a coil resistance equivalent value at the intake air temperature TA is retrieved from a map showing the correspondence between the intake air temperature TA and the coil resistance equivalent value of the electromagnetic coil 53, and the initial coil resistance equivalent value is obtained. R
Set to CI. Here, the coil resistance value is used because the value obtained in step S16 described later corresponds to the electric resistance value of the electromagnetic coil 53.

Further, in step S15, as shown in FIG. 9, a map in which a coefficient corresponding to an estimated coil resistance equivalent value R described later is stored is searched, and a correction coefficient KR is determined.
Is set as Since the estimated coil resistance equivalent value R described later is proportional to the electric resistance value of the electromagnetic coil 53, that is, the temperature of the electromagnetic coil 53, the correction coefficient KR becomes smaller as the degree of warm-up of the internal combustion engine 1 becomes smaller, Electromagnetic coil
The smaller the electrical resistance value or the estimated coil resistance equivalent value R of 53 is, the greater the influence of the initial coil resistance equivalent value RCI is.
Since the influence of the initial coil resistance equivalent value RCI becomes smaller as the warm-up progresses, the oil temperature decreases linearly around the time when the rate of rise of the oil temperature slows down, and after the warm-up is completed, the oil temperature rises. Is set to "0" when a substantially steady state is reached. Of course, this coefficient is appropriately set by an experiment or the like. If the influence of the initial coil resistance equivalent value RCI on the estimated coil resistance equivalent value R can be evaluated, the coefficient with respect to the change of the estimated coil resistance equivalent value R can be evaluated. The transition of the value is not limited to that shown in FIG. In the first loop of the estimated oil temperature calculation routine, since the estimated coil resistance equivalent value R has not been obtained, the correction coefficient KR is set to “1.
0 ".

The value obtained by multiplying the correction coefficient KR by the initial coil resistance equivalent value RCI is defined as the correction resistance equivalent value RC. Here, the initial coil resistance equivalent value RCI indicates a state in which the internal combustion engine 1 is placed immediately before the start of the internal combustion engine 1, that is, an equivalent value of the electric resistance value of the electromagnetic coil 53 in the initial state. The temperature of the electromagnetic coil 53 when the estimated oil temperature duty DT is output in step S4 of the estimation duty ratio output routine, that is, the electromagnetic coil
It has an effect on the resistance value of 53. Therefore, the correction resistance equivalent value RC reflects the state when the solenoid valve 50 is placed immediately before the start of the internal combustion engine 1, and furthermore, the electric resistance value of the electromagnetic coil 53 after the start of the internal combustion engine 1. Is considered in consideration of the degree of involvement of the initial coil resistance equivalent value RCI. Therefore, this correction resistance equivalent value R
By using C for oil temperature estimation, more accurate oil temperature estimation becomes possible.

In the subsequent step S16, the oil temperature estimation duty ratio is calculated based on the current amount I detected when the energization signal of the oil temperature estimation duty ratio DT obtained in the oil temperature estimation duty ratio output routine is output. The correction resistance equivalent value RC obtained in step S15 is added to the value obtained by dividing DT to obtain an estimated coil resistance equivalent value R of the electromagnetic coil 53.

Here, in general, the duty ratio of the energization signal and the amount of current I supplied under the energization signal of the duty ratio are in a proportional relationship, and the ratio between the duty ratio and the amount of current I is: It corresponds to the electric resistance value. The oil temperature estimation duty ratio DT and the electromagnetic coil
The ratio with the amount of current I supplied to 53 reflects the electric resistance value of the electromagnetic coil 53.

Therefore, the oil temperature estimation duty ratio DT
The estimated coil resistance equivalent value R, which is a ratio between the current value I and the current amount I, is a temperature index value indicating the electric resistance value of the electromagnetic coil 53, that is, the temperature of the electromagnetic coil 53 proportional to the electric resistance value.

In the following step S17, as shown in FIG. 10, a value obtained by searching a map showing the correspondence between the estimated coil resistance equivalent value R and the estimated oil temperature T is used as the estimated oil temperature T.
After that, the process proceeds to step S18. In step S18, in order to reduce the influence of the fluctuation of the current amount I, a smoothing calculation is performed using the previous value T (n-1) of the estimated oil temperature T,
At that time, as described above, in order to reduce the influence of the oil temperature fluctuation, an averaging coefficient including different set values KS and KN is used according to a lapse of time immediately after the start is completed. Then, the obtained value is set as the current value T (n) of the estimated oil temperature T, and the estimated oil temperature T is updated in the next and subsequent loops.
In step S14, the oil temperature estimation execution flag FT is set to "0".
If so, the routine ends, and in this case, the estimated oil temperature T obtained so far is held. Here, step S15,
Means for executing a series of steps including S16, S17, and S18 is oil temperature estimating means.

Hereinafter, an example of using the estimated oil temperature T obtained in the estimated oil temperature calculation routine in controlling the variable phase mechanism 20 of the valve train control device will be described.

The flowcharts of FIGS. 11 and 12 are as follows.
This shows a target cam phase calculation routine for calculating a target cam phase CM of the intake cam 11 used when performing the feedback control of the variable phase mechanism 20. This routine is executed by the electronic control unit 47 every set time.

First, when it is determined in step S21 that the internal combustion engine 1 is starting (cranking), step S21 is executed.
At 22, a set time t4 (for example, 3 seconds) is set in an operation inhibition timer TS for inhibiting the operation of the phase variable mechanism 20 immediately after the start is completed, the target cam phase CM is set to “0” in step S23, and in step S24. The control permission flag F of the variable phase mechanism 20 indicating whether to permit the operation of the variable phase mechanism 20 is set to “0”, and the operation is prohibited.

When the start of the internal combustion engine 1 is completed, until the operation prohibition timer TS times out in step S25,
Proceeding to step S23 and step S24, the operation of the variable phase mechanism 20 is prohibited. When the operation inhibition timer TS times out and three seconds elapse after the start is completed, step 26 is executed.
Proceed to. If a failure of the variable phase mechanism 20 or a failure of a sensor or the like has occurred in step S26, the process proceeds to steps S23 and S24, and the operation of the variable phase mechanism 20 is prohibited.

If no failure has occurred in step S26, the operation proceeds to step S27. In step S27, FIG.
As shown in FIG. 3, in order to set the operation mode of the variable phase mechanism 20 in accordance with the estimated oil temperature T, the estimated oil temperature T is fixed such that the target cam phase CM of the variable phase mechanism 20 has a predetermined fixed value. Fixed control mode start estimated oil temperature TH for starting control mode
(For example, approximately −10 ° C.), and when it is determined that the temperature is lower than the predetermined value, the operation is prohibited, and in step S29, the control of the phase variable mechanism 20 in the fixed control mode is permitted. The fixed control permission flag FH indicating whether or not the target cam phase C is set to "0" in step S23.
M is set to "0", and in step S24, the control permission flag F is set to "0", and its operation is prohibited.

If it is determined in step S27 that the estimated oil temperature T is equal to or higher than the fixed control mode start estimated oil temperature TH, the process proceeds to step S28, in which the estimated oil temperature T is changed to the target cam phase CM of the phase variable mechanism 20. It is determined whether or not it is lower than a variable control mode start estimated oil temperature TV (for example, about 30 ° C.) that starts a variable control mode that is made variable according to the intake pressure P and the rotation speed Ne, and is determined to be low. The fixed control mode area is reached, the fixed control permission flag F is set in step S30.
H is set to "1", then, in step S31, the target cam phase CM is set to a preset fixed value CMH, and in step S32, the control permission flag F is set to "1". The feedback control in the fixed control mode is permitted.

If it is determined in step S28 that the estimated oil temperature T is equal to or higher than the variable control mode start estimated oil temperature TV, the variable control mode range is reached, and the routine proceeds to step S33, where the fixed control permission flag FH is set to "0". ", And the process proceeds to step S34. In step S34, it is determined whether or not the internal combustion engine 1 is in an idling operation.
Proceed to steps S23 and S24 to change the phase
Operation of 20 is prohibited.

If idling is not being performed in step S34, it is determined in step S35 whether or not the estimated oil temperature T is higher than a set value T1 corresponding to a high oil temperature. When it is determined to be high, the process proceeds to steps S23 and S24, and the operation of the variable phase mechanism 20 is prohibited.

If it is determined in step S35 that the estimated oil temperature T is equal to or lower than the set value T1, the process proceeds to step S36, in which a map of the target cam phase CM in which the intake pressure P and the rotation speed Ne are set as parameters is searched. The value obtained by the search is used as the target cam phase CM.

In the following step S37, the target cam phase CM
The absolute value of the deviation obtained by subtracting the value of the previous target cam phase CM (n-1) from the previous value is compared with the limit value DMC of the change amount of the cam phase. If the absolute value of the deviation is smaller than the limit value DMC, Proceeding to S38, the retrieved map value is set as the current target cam phase CM (n).

As a result of the comparison in step S37, if the absolute value of the deviation is equal to or larger than the limit value DMC, in step S39 C
The sign of M-CM (n-1) is determined, and if the sign is positive, in step S40, the cam phase is changed to the previous target cam phase CM (n-1) in order to gradually change the cam phase to the advance side. The value obtained by adding the limit value DMC is set as the current target cam phase CM (n). If the inequality expression is not satisfied in step S39, the value obtained by subtracting the limit value DMC from the previous target cam phase CM (n-1) is used in step S41 in order to gradually change the cam phase to the retard side. The target cam phase CM (n) is set. Thereafter, in step S32, the control permission flag F is set to "1", and the feedback control in the variable control mode of the variable phase mechanism 20 is permitted.

As shown in FIG. 13, the estimated variable control mode start oil temperature TV is the fixed control mode start estimated oil temperature T
H is set higher than H. Then, the estimated oil temperature T
However, in the temperature range lower than the fixed control mode start estimated oil temperature TH, the viscosity of the hydraulic oil is high, so that even if feedback control is performed, it is difficult to achieve good responsiveness and convergence to the target value. For this reason, the operation is prohibited. Although the estimated oil temperature T is equal to or higher than the fixed control mode start estimated oil temperature TH, the variable control mode start estimated oil temperature TV
In the fixed control mode region where the viscosity of the hydraulic oil is not lower than the viscosity of the hydraulic oil in the variable control mode region where responsiveness and convergence are required, the target cam phase C
By the feedback control in the fixed control mode in which M is a fixed value, the output, the fuel consumption, and the exhaust emission in a relatively wide load range and the rotation speed range are improved as compared with the case where the operation is prohibited. And, in the variable control mode range, by the feedback control in the variable control mode,
The power, fuel efficiency, and exhaust emissions are optimized over a wide range of loads and speeds.

In the next example, the intake cam is
In the feedback control in the eleventh cam phase variable control mode, the estimated oil temperature T is used. 14 and 15 show a routine of this feedback control, and this routine is also executed by the electronic control unit 47 every set time.

First, in step S51, the failure flag FNG of the variable phase mechanism 20 is not set to "1", the variable phase mechanism 20 is normal, and the control permission flag F is set to "1" in step S52. When the variable phase mechanism 20 is in operation, the target cam phase CM calculated in the target cam phase calculation routine and the actual cam calculated from the outputs of the intake camshaft sensor 16 and the crankshaft sensor 18 in step S53. The deviation DM from the actual cam phase C which is the cam phase is calculated, and the actual cam phase C (n-1) in the previous loop and the actual cam phase C (n) in the current loop are calculated in step S54. A difference DC is calculated.

If the control permission flag F has changed from "0" to "1" in the subsequent step S55, that is, if the operation of the phase variable mechanism 20 has been switched from prohibition to permission in this loop. In step S56, the deviation DM is compared with a first feedforward control determination value D1, for example, 10 degrees corresponding to a crank angle. As a result, if the deviation DM is larger than the first feedforward control determination value D1, the feedforward control flag FFF is set to "1" in step S57, and the phase variable mechanism 20, which should be feedback controlled, is subjected to feedforward control. You.

That is, in step S58, the last integral term DI
(N-1) is set to "0", and in step S59, the solenoid valve
After the duty value D (n) in the current loop of the duty ratio of the energization signal output to 50 is set to the upper limit value DH1, in step S73, the duty ratio DOUT of the solenoid valve 50 is changed to the current duty value D (n). It is said. In the subsequent loop, since the determination result of step S55 is NO and the determination result of step S60 is YES, the difference DM and the first feedforward control determination value D are determined again in step S56.
The magnitude is compared with 1 and the process proceeds to step S73 via steps S57 to S59 while the deviation DM is large.

Therefore, if the deviation DM between the target cam phase CM and the actual cam phase C is large when the control of the variable phase mechanism 20 is started, the duty value D (n) is a constant this time while the state continues. By setting the upper limit value DH1, the phase variable mechanism 20 is subjected to feedforward control. In this way, by continuing the feedforward control only while the convergence is concerned because the deviation DM is large, it is possible to achieve both responsiveness and convergence.

In step S56, the deviation D from the beginning of the control is calculated.
If M is equal to or less than the first feedforward control determination value D1, or if the deviation DM becomes equal to or less than the first feedforward control determination value D1 during the above-described feedforward control, the feedforward control of the phase variable mechanism 20 is performed in step S61. When the control flag FFF is set to “0”,
Proceed to step S62. In step S62, the previous integral term DI
If (n-1) is "0", the previous integration term DI (n-1) is set to an initial value in step S63.

As shown in FIG. 16, the initial value is retrieved from a map using the estimated oil temperature T as a parameter. The initial value is set to be smaller as the estimated oil temperature T is lower. As a result, the change of the cam phase at the time of low oil temperature where the viscosity of the hydraulic oil is large is slowed, and the target cam phase CM
Overshooting can be suppressed, and the convergence to the target value can be improved.

In step S64, the deviation DM (when the target cam phase CM is larger than the actual cam phase C) is compared with a second feedforward control determination value D2 smaller than the first feedforward control determination value D1. As a result, if the deviation DM between the two is large, the current duty value D (n) is set to the upper limit value DH2 in step S65, and then the duty ratio DOUT of the energization signal to the solenoid valve 50 is set in step S73.
Is the current duty value D (n).

Similarly, in step S66, the deviation DM (when the target cam phase CM is smaller than the actual cam phase C) is equal to the third feedforward control determination value D3 whose absolute value is smaller than the first feedforward control determination value D1. Be compared.
As a result, if the deviation DM between the two is large, step S
After the current duty value D (n) is set to the lower limit value DL2 at 67, the duty ratio DOUT is set to the current duty value D (n) at step S73.

As described above, even after the deviation DM becomes equal to or smaller than the first feedforward control judgment value D1 in step S56, the deviation DM is equal to or smaller than the second and third feedforward control judgment values D2 and D3 in steps S64 and S66. Until the current time, the duty value D (n) is changed from the upper limit value DH1 to the upper limit value DH2 or the lower limit value DL2 and the feedforward control is continued, so that both the responsiveness and the convergence can be achieved.

When the absolute value of the deviation DM becomes sufficiently small by the above-mentioned feedforward control and both steps S64 and S66 are not satisfied, in step S68, the proportional term gain KP,
After the integral term gain KI and the derivative term gain KV are calculated, in step S69, the proportional term DP, the integral term DI, and the derivative term DV are respectively calculated by the following equations.

DP = KP * DM DI = KI * DM + DI (n-1) DV = KV * DC In step S70, the current duty value D (n) of the PID feedback control is determined by the proportional term DP, the integral term DI, and the differential term. It is calculated as the sum of the term DV.

Here, the proportional term gain KP, the integral term gain KI, and the differential term gain KV, which are the control gains of the feedback control in the variable control mode, are the sign of the deviation DM, the magnitude of the absolute value of the deviation DM, and the estimated oil. Using the temperature T and the rotation speed Ne as parameters, the proportional term gain KP, the integral term gain KI, and the derivative term gain KV for the control gain of the phase shift to the advance side and the proportionality for the phase shift to the retard side The control gains of the term gain KP, the integral term gain KI, and the derivative term gain KV are retrieved from the table.

For example, if the target cam phase CM is the actual cam phase C
If the deviation DM is larger than the predetermined value and the magnitude of the deviation DM is smaller than a predetermined value, as shown in FIG. 17, the set estimated temperature T2, the first set rotation Proportional term gain KP suitable for feedback control in the variable control mode in which followability to the changing target cam phase CM is required in each of the six regions divided by the number Ne1 and the second set rotation speed Ne2, A table in which an integral term gain KI and a differential term gain KV are set is prepared, and these gains are changed according to the estimated oil temperature T and the rotation speed Ne.

Then, the deviation DM is positive and the deviation D
If the magnitude of M is equal to or greater than a predetermined value, the target cam phase C
M is smaller than the actual cam phase C, the deviation DM is negative,
When control to the retard side is required, and the magnitude of the absolute value of the deviation DM is smaller than a predetermined value, and when the deviation DM is negative and the magnitude of the absolute value of the deviation DM is a predetermined value. For each of the above cases, a table similar to the table shown in FIG. 17 is prepared, and each of the tables is provided with a feedback at the time of the variable control mode in which followability to the changing target cam phase CM is required. Control gains suitable for control are set, and these gains are changed according to the estimated oil temperature T and the rotation speed Ne.

In any of the above cases, when the estimated oil temperature T is low or when the rotation speed Ne is low,
If the viscosity of the hydraulic oil is high or if the pressure of the hydraulic oil is insufficient, the ability to follow the target cam phase CM is reduced. Therefore, the proportional term gain KP, the integral term gain KI, and the derivative term gain KV are determined by the estimated oil temperature. The higher the T and the higher the rotational speed Ne, the larger the value is set, so that appropriate follow-up and responsiveness according to each engine operating state can be obtained, and hunting is prevented. Feedback control is performed.

The proportional gain KP, the integral gain KI, and the differential gain KV, which are the control gains used in the feedback control in the fixed control mode set in step S31, are also changed in the variable control mode. Unlike the control gain, the proportional term gain K having a value set from the viewpoint of stably maintaining the fixed target cam phase CM.
P, each control gain including the integral term gain KI and the differential term gain KV is a target cam phase CM having a fixed value CMH.
A table using the sign of the difference DM between the actual cam phase C and the magnitude of the absolute value of the difference, the estimated oil temperature and the rotation speed Ne as parameters, and the same table as the table in FIG. 17 is prepared. I have.

Subsequently, in steps S71 and S72, a limit process for the current duty value D (n) is executed. That is, if the current duty value D (n) exceeds the upper limit value DH3 in step S71, the upper limit value DH2 is set to the current duty value D (n) in step S65, and the current duty value D (n) is set in step S72. Is less than the lower limit value DL3, the lower limit value DL2 becomes equal to the current duty value D in step S67.
(N). Then, in step S73, the phase variable mechanism 20 performs feedback so that the deviation DM between the target cam phase CM and the actual cam phase C converges to "0" with the duty value D (n) as the duty ratio DOUT of the energization signal. Controlled.

In step S51, the phase variable mechanism 20
Is in failure and the failure flag FNG is set to "1", the current duty value D is determined in step S74.
(N) is set to “0”, and the phase variable mechanism 20 is set to the most retarded state.

If the control permission flag F is set to "0" in step S52 and the operation of the variable phase mechanism 20 is prohibited, the feedforward control flag FFF is set to "0" in step S75. Then, in step S76, the previous integral term DI (n-1) is set to "0", and in step S77, the current duty value D (n) of the phase variable mechanism 20 is set to the lower limit DL1, and then in step S73.
The duty ratio DOU of the energization signal output to the solenoid valve 50
T is the current duty value D (n).

In the following example, the estimated oil temperature T is used at the time of transition of the control mode of the variable phase mechanism 20, that is, at the time of transition between the fixed control mode area and the variable control mode area.

For example, when shifting from the fixed control mode to the variable control mode in accordance with a change in the estimated oil temperature T accompanying a change in the operating state of the internal combustion engine 1, immediately after the shift, FIG.
The same processing as the processing in steps S37 to S41 in the variable control mode described with reference to the flowchart of FIG. 12 is performed.

That is, only immediately after shifting from the fixed control mode to the variable control mode (this time can be detected as, for example, the time when the fixed control mode flag FH changes from “1” to “0”), the intake pressure P and the rotation The absolute value of the deviation obtained by subtracting the previous target cam phase CM (n-1) from the target cam phase CM retrieved from the map using the number Ne as a parameter is compared with the cam phase limit value DMT. If it is smaller than the limit value DMT, the target cam phase C
M is the current target cam phase CM (n).

When the absolute value of the deviation is equal to or greater than the limit value DMT, if the expression: CM-CM (n-1) is positive,
In order to gradually change the cam phase to the advance side, the advance target limit value DM for the advance side is added to the previous target cam phase CM (n-1).
The value obtained by adding TA is set as the current target cam phase CM (n). Further, if the above equation is "0" or negative, the retard limit value DMTR from the previous target cam phase CM (n-1) to the retard side is used to gradually change the cam phase to the retard side.
Is set as the current target cam phase CM (n).

As shown in FIG. 18, the limit value DMT is retrieved from a map using the estimated oil temperature T as a parameter. Similarly, the advance limit value DMTA and the retard limit value DMTR are also searched. Using the estimated oil temperature T as a parameter, a search is performed from each of the maps similar to the map in FIG. Each of these limit values is set to be smaller as the estimated oil temperature T is lower, whereby the change of the cam phase at the time of low oil temperature where the viscosity of the hydraulic oil is large, Overshoot from the value can be suppressed, and the convergence to the target value can be improved.

As described above, when the control mode of the feedback control is shifted, when the deviation between the target cam phase CM searched in the map and the previous target cam phase CM (n-1) is large, the target cam phase CM is switched at a stroke. By gradually switching to a smaller target value, it is possible to prevent overshoot in control due to a sudden change in cam phase and a sudden change in engine output.

Further, the estimated oil temperature T is changed to the target cam phase CM
It can also be used to determine the execution condition when detecting an abnormality of the phase variable mechanism 20 from the followability of the actual cam phase C with respect to. In this case, first, it is determined whether or not the estimated oil temperature T is within a predetermined temperature range determined by the lower limit and the upper limit. This temperature range is a temperature range in which the viscosity of the hydraulic oil is at an appropriate value in consideration of the fact that the viscosity of the hydraulic oil also affects the ability to follow the target value. The temperature is around 60 ° C, the upper limit is the actual oil temperature is 10
The estimated oil temperature T is set to about 0 ° C.

When it is determined that the estimated oil temperature T is within the above temperature range, the actual cam phase C is changed to the target cam phase CM.
It is determined whether or not the allowable range is equal to or greater than a lower limit obtained by subtracting the lower allowance from the upper limit and equal to or less than an upper limit obtained by adding the upper allowance to the target cam phase CM. When the actual cam phase C falls below the lower limit value or exceeds the upper limit value, it is determined that the actual cam phase C does not follow the target cam phase CM, and when this state continues for a predetermined time, An alarm is issued by turning on a lamp. In this way, by using the estimated oil temperature T as the execution condition of the abnormality detection, it is possible to perform the abnormality detection with high accuracy.

Hereinafter, the effects of the embodiment configured as described above will be described. Steps S15, S16, S17, S
An electromagnetic valve 50 that controls the supply and discharge of hydraulic oil to and from the hydraulic variable phase mechanism 20
Is obtained based on the estimated coil resistance equivalent value R, which is the temperature index value of the electromagnetic coil 53, an expensive oil temperature sensor is not required, and the cost of the valve train control device can be reduced.

Further, the solenoid valve 50 having the spool 52 provided in the oil passage is directly under the influence of the oil temperature since it is always in contact with the hydraulic oil at the time of supply and discharge. The 50 electromagnetic coils 53 are also strongly affected by the oil temperature, and the oil temperature and the temperature of the electromagnetic coil 53 have a strong correlation. Therefore, the estimated oil temperature T obtained based on the estimated coil resistance equivalent value R, which is a value related to the temperature of the electromagnetic coil 53, reflects the temperature transition of the oil temperature more accurately than the conventional cooling water temperature. It will be.

The estimated coil resistance equivalent value R is determined by determining whether the energizing signal for the oil temperature estimating duty ratio DT that determines the operation amount of the driven solenoid valve 50 is different from the energizing signal during the output of the energizing signal. It is obtained by using the current amount I supplied to the electromagnetic coil 53. That is, the ratio between the oil temperature estimation duty ratio DT and the amount of current I supplied to the electromagnetic coil 53 is equivalent to the electric resistance value of the electromagnetic coil 53,
Since it reflects the electric resistance value of the electromagnetic coil 53, it can be a temperature index value of the electromagnetic coil 53,
Moreover, there is a strong correlation between the temperature index value and the oil temperature. Therefore, it is possible to accurately estimate the oil temperature based on the energization signal for driving the electromagnetic valve 50 and the current amount I having a clear correspondence with the temperature of the electromagnetic coil 53 reflecting the oil temperature.

Further, the ratio between the oil temperature estimating duty ratio DT and the current amount I is corrected by the intake air temperature TA which is the ambient temperature of the internal combustion engine 1 immediately before starting. This intake air temperature TA keeps the internal combustion engine 1 and the solenoid valve 50 until just before the start.
This reflects the state where the electromagnetic coil 53 is placed, and has an effect on the temperature of the electromagnetic coil 53. The temperature of the electromagnetic coil 53 immediately before the start of the internal combustion engine 1 also affects the temperature of the electromagnetic coil 53 placed under the influence of the oil temperature after the start of the internal combustion engine 1. Therefore, a more accurate estimated oil temperature can be obtained by using a temperature index value that takes into account the intake air temperature TA immediately before the start of the internal combustion engine 1 that affects the temperature index value of the electromagnetic coil 53.

The oil temperature is estimated after the completion of the start of the internal combustion engine 1 and for the time during which the operation of the variable phase mechanism 20 is prohibited after the start of the stopped internal combustion engine 1 is started. Since it is executed during this time, the oil temperature can be estimated without affecting the operation of the phase variable mechanism 20. In addition, the obtained estimated oil temperature T can be used as an operation start condition of the phase variable mechanism 20, or the phase variable mechanism 20 reflecting the oil temperature can be controlled from an early stage after the start of the internal combustion engine 1 is completed. For example, over a wide operating range of the internal combustion engine 1, more accurate control reflecting the oil temperature of the phase variable mechanism 20 can be performed.

In the above embodiment, the phase variable mechanism 20
Is provided only on the intake camshaft 6, but the phase variable mechanism 20 is provided.
May be provided only on the exhaust camshaft 7 or may be provided on the intake camshaft 6 and the exhaust camshaft 7. further,
The variable valve operating characteristic mechanism is the variable phase mechanism 20, but may be a mechanism that changes valve operating characteristics such as the opening period of the intake valve 13 or the exhaust valve 14 and the lift amount.

[Brief description of the drawings]

FIG. 1 is an overall view of an internal combustion engine to which the present invention is applied.

FIG. 2 is a sectional view of a variable phase mechanism.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a conceptual diagram of an oil passage of a hydraulic oil and a control system.

FIG. 5 is a sectional view of a solenoid valve.

FIG. 6 is a flowchart of an oil temperature estimation duty ratio output routine.

FIG. 7 is a flowchart of an estimated oil temperature calculation routine.

FIG. 8 is a diagram showing a map for searching for a coil resistance equivalent value from an intake air temperature.

FIG. 9 is a diagram showing a map for searching for a coefficient from an estimated coil resistance equivalent value.

FIG. 10 is a diagram showing a map for searching an estimated oil temperature from an estimated coil resistance equivalent value.

FIG. 11 is a first branch diagram of a flowchart of a target cam phase calculation routine.

FIG. 12 is a second diagram of the flowchart of the target cam phase calculation routine.

FIG. 13 is a diagram illustrating an operation mode of a phase variable mechanism with respect to an estimated oil temperature.

FIG. 14 is a first partial view of a flowchart of feedback control in the variable control mode of the variable phase mechanism.

FIG. 15 is a first branch diagram of a flowchart of feedback control in the variable control mode of the variable phase mechanism.

FIG. 16 is a diagram showing a map for searching for an integral term initial value from an estimated oil temperature.

FIG. 17 is a diagram showing a control gain table.

FIG. 18 is a diagram showing a map for searching for a limit value from an estimated oil temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Piston, 3 ... Connecting rod, 4 ... Crankshaft, 5 ... Drive sprocket, 6 ...
Intake cam shaft, 7: Exhaust cam shaft, 8: Intake cam sprocket, 9: Exhaust cam sprocket, 10: Timing chain, 11: Intake cam, 12: Exhaust cam, 13: Intake valve, 14: Exhaust valve, 15: Switching Mechanism, 16, 17, 18 ... sensor, 20 ... variable phase mechanism, 21 ... boss member, 22 ... pin, 23 ... bolt, 24 ... housing, 25 ... plate, 26 ... bolt, 27 ... lock pin, 28 ... spring, 29, 30 ... seal member, 31 ... advance chamber, 32 ... retard chamber, 33, 34, 35, 36 ... oil passage, 40 ... oil pump, 41 ... oil pan, 42, 43, 44, 45 ... oil passage , 46 ... hydraulic switching valve, 47 ... electronic control unit, 50 ... solenoid valve, 51 ... sleeve, 52 ... spool, 53 ... electromagnetic coil, 54 ... spring.

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[Procedure amendment]

[Submission date] December 27, 1999 (1999.12.
27)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Valve operating control device for an internal combustion engine

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve control apparatus for an internal combustion engine provided with a hydraulic valve operating characteristic variable mechanism for changing valve operating characteristics such as opening / closing timing of an intake valve or an exhaust valve as an engine valve. More specifically, the present invention relates to a valve train control device provided with oil temperature estimating means for estimating the temperature of hydraulic oil supplied to and discharged from a valve operating characteristic variable mechanism.

[0002]

2. Description of the Related Art Conventionally, a valve operating device for an internal combustion engine includes a valve, such as an opening / closing timing of an intake valve or an exhaust valve, a lift amount, and a valve opening period, from the viewpoint of improvement of engine output, fuel efficiency and exhaust emission. Some include a hydraulic valve operating characteristic variable mechanism whose operating characteristic is variable according to the operating state of the internal combustion engine.

[0003] Since this variable valve operating characteristic mechanism is driven by hydraulic oil supplied and discharged by a hydraulic oil control valve, its behavior greatly influences the oil temperature of the hydraulic oil (hereinafter simply referred to as "oil temperature"). receive. Therefore, in this type of variable valve operating characteristic mechanism, control is performed in consideration of the effect of the oil temperature.

For example, a valve timing control device for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. H11-2142 adjusts the rotation phase of a camshaft by the hydraulic pressure of hydraulic oil adjusted by a linear solenoid valve whose amount of current is controlled. A hydraulic valve timing mechanism for changing the rotation phase is provided, and the valve timing mechanism is configured such that the most advanced side of the rotation phase is limited by the stopper before the duty for controlling the amount of energization reaches 100%.

[0005] Immediately after the target value is switched to the most advanced angle side, the linear solenoid has a predetermined time until the actual rotational phase changes to the most advanced angle side (stopper position).
% Duty is given, and after the predetermined time elapses, the duty is reduced to a smaller value capable of holding the rotation phase on the most advanced side, thereby saving power consumption and suppressing a rise in coil temperature. It is. At this time, if the oil temperature is low, the time required to reach the most advanced side becomes longer. Therefore, the predetermined time is corrected by the oil temperature so that the predetermined time becomes an appropriate value. You.

[0006]

The provision of an oil temperature sensor for detecting the oil temperature increases the cost of an apparatus having a variable valve timing mechanism because the oil temperature sensor is relatively expensive. Become. Also, instead of providing an oil temperature sensor, it is conceivable to use a water temperature sensor for detecting the temperature of cooling water provided for another device, but between the oil temperature and the water temperature, Delays in heat transfer,
Due to differences in the specific heats of the two and the like, a shift may occur in the transition of the temperature change, and it cannot be said that there is always a strong correlation. Therefore, in the case of using the water temperature sensor instead of the oil temperature sensor, it has been difficult to obtain good control accuracy of the hydraulic valve timing variable mechanism.

[0007] The present invention has been made in view of such circumstances, and the temperature of hydraulic oil of a hydraulic valve operating characteristic variable mechanism can be relatively accurately measured without using an expensive oil temperature sensor. It is an object of the present invention to provide a valve operating control device for an internal combustion engine including an oil temperature estimating means that can be estimated.

[0008]

The invention according to claim 1 of the present application has a hydraulic valve operating characteristic variable mechanism for changing the operating characteristics of an engine valve, and an electromagnetic coil. Electromagnetic hydraulic oil control means for controlling the supply and discharge of hydraulic oil to and from the variable characteristic mechanism; control means for controlling the drive of the hydraulic oil control means; and controlling the temperature of the hydraulic oil based on a temperature index value of the electromagnetic coil. A valve operating device for an internal combustion engine, comprising: an oil temperature estimating means for estimating the oil temperature.

According to the first aspect of the present invention, the estimated oil temperature is obtained based on the temperature index value of the electromagnetic coil of the hydraulic oil control means for controlling the supply and discharge of the hydraulic oil to and from the hydraulic valve operating characteristic variable mechanism. Therefore, an expensive oil temperature sensor is not required, and the cost of the valve train control device can be reduced.

In addition, since the hydraulic oil control means is always in contact with the hydraulic oil at the time of supply and discharge, the hydraulic oil control means is directly affected by the oil temperature. It is strongly affected and has a strong correlation between the oil temperature and the temperature of the electromagnetic coil. Therefore, the estimated oil temperature obtained based on the temperature index value, which is a value related to the temperature of the electromagnetic coil, reflects the temperature transition of the oil temperature more accurately than the conventional cooling water temperature.

According to a second aspect of the present invention, in the valve operating control device for an internal combustion engine according to the first aspect, the temperature index value includes an energization signal output from the control means to the hydraulic oil control means, This is a value obtained based on the amount of current supplied to the electromagnetic coil while the signal is being output.

According to the second aspect of the invention, the temperature index value is supplied to the electromagnetic coil while the energization signal is being output and the energization signal for determining the operation amount of the driven hydraulic oil control means. It is obtained by using the current amount. The amount of current at this time depends on the electric resistance value of the electromagnetic coil, and since the electric resistance value is a function of the temperature of the electromagnetic coil, the value obtained based on the energization signal and the current amount is It serves as a temperature index value, and there is a strong correlation between the temperature index value and the oil temperature. Therefore, it is possible to accurately estimate the oil temperature based on the energization signal for driving the hydraulic oil control means and the amount of current having a clear correspondence with the temperature of the electromagnetic coil reflecting the oil temperature.

According to a third aspect of the present invention, in the valve operating control apparatus for an internal combustion engine according to the first or second aspect, the oil temperature estimating means includes a valve operating characteristic variable after completion of starting the internal combustion engine. The temperature is estimated during the operation prohibition time of the mechanism.

According to the third aspect of the invention, the oil temperature is estimated after the start of the internal combustion engine is completed, and after the operation of the stopped internal combustion engine is started, the valve operating characteristic variable mechanism is operated. Since it is executed during a period that does not lead to the operation, the oil temperature can be estimated without affecting the operation of the variable valve operation characteristic mechanism. In addition, the obtained estimated oil temperature can be used as an operation start condition of the variable valve operating characteristic mechanism, and the variable valve operating characteristic mechanism that reflects the oil temperature can be controlled from an early stage after the internal combustion engine is started. , Over a wide operating area of the internal combustion engine,
More precise control reflecting the oil temperature of the valve operating characteristic variable mechanism can be performed.

According to a fourth aspect of the present invention, in the valve control apparatus for an internal combustion engine according to any one of the first to third aspects, the temperature index value is determined by an ambient temperature of the internal combustion engine immediately before starting. It is the corrected value.

According to the present invention, the temperature index value is corrected by the ambient temperature of the internal combustion engine immediately before starting. This ambient temperature is maintained until the internal combustion engine,
Further, the state reflects the state where the electromagnetic coil of the hydraulic oil control means is placed, and has an effect on the temperature of the electromagnetic coil. The temperature of the electromagnetic coil immediately before the start of the internal combustion engine also affects the temperature of the electromagnetic coil placed under the influence of the oil temperature after the start of the internal combustion engine is completed. Therefore, a more accurate estimated oil temperature can be obtained by using the temperature index value that takes into account the ambient temperature immediately before the start of the internal combustion engine that affects the temperature index value of the electromagnetic coil.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, an internal combustion engine 1 is a spark ignition type 4 mounted on a vehicle.
This is a cylinder DOHC internal combustion engine, and each piston 2 is connected to a crankshaft 4 via a connecting rod 3. As shown in FIG. 1, a drive sprocket 5 provided at a shaft end of a crankshaft 4 and intake and exhaust cam sprockets provided at one shaft end of an intake camshaft 6 and an exhaust camshaft 7, respectively. 8 and 9 are connected via a timing chain 10, and both camshafts 6 and 7 are rotationally driven at a reduction ratio of 1/2 of the rotation of the crankshaft 4.

Each cylinder has two intake valves 13, which are engine valves driven by an intake cam 11 provided on the intake camshaft 6.
And two exhaust valves 14, which are engine valves driven by an exhaust cam 12 provided on the exhaust cam shaft 7.
Between the intake camshaft 6 and the intake valve 13, and between the exhaust camshaft 7 and the exhaust valve 14, the lift amounts and the valve opening periods of the valves 13 and 14 are set according to the rotation speed Ne of the internal combustion engine 1. A switching mechanism 15 for switching is provided. In the intake camshaft 6, the rotation end of the intake camshaft 6 with respect to the crankshaft 4 is steplessly advanced or retarded at the shaft end where the intake cam sprocket 8 is provided, so that the intake cam 11 A hydraulic phase variable mechanism 20, which is a valve operating characteristic variable mechanism for changing the opening / closing timing of the intake valve 13 by advancing or retarding the cam phase steplessly, is provided.

As shown in FIGS. 2 and 3, the variable phase mechanism 20 has a support hole 21a formed at the center of a substantially cylindrical boss member 21 coaxially with the shaft end of the intake camshaft 6. The boss member 21 and the intake camshaft 6 are fitted so as to be relatively non-rotatable by pins 22 and bolts 23. The intake cam sprocket 8 around which the timing chain 10 is wound is formed in a substantially cup shape having a circular concave portion 8a, and sprocket teeth 8b are formed on the outer periphery thereof. An annular housing 24 fitted into the concave portion 8a of the intake cam sprocket 8 and a plate 25 superposed in the axial direction thereof are connected to the intake cam sprocket 8 with four bolts 26 penetrating therethrough.

Therefore, the boss member 21 integral with the intake camshaft 6 is housed in a space surrounded by the intake cam sprocket 8, the housing 24 and the plate 25 so as to be relatively rotatable with respect to them. A lock pin 27 is slidably fitted in a pin hole 21c penetrating through the boss member 21 in the axial direction. The lock pin 27 is compressed by a spring 28 mounted between the plate 25 and the air intake. The cam sprocket 8 is urged in a direction to engage with a lock hole 8c formed in the cam sprocket 8.

Inside the housing 24, four fan-shaped concave portions 24a centered on the axis of the intake camshaft 6 are formed at 90 ° intervals, and four vanes projecting radially from the outer periphery of the boss member 21 are formed. 21b is fitted in the concave portion 24a so as to be relatively rotatable within a central angle range of 30 °. Four sealing members 29 provided at the tips of the four vanes 21b slidably abut the ceiling wall of the recess 24a, and four sealing members 30 provided on the inner peripheral surface of the housing 24 are bosses. An advancing chamber 31 and a retarding chamber 32 are defined on both sides of each vane 21b by slidably contacting the outer peripheral surface of the member 21.

Inside the intake camshaft 6, an advance oil passage 33 and a retard oil passage 34 are formed, and the advance oil passage 33 penetrates the boss member 21 in four radial directions. 4 via oilway 35
The retarding oil passages 34 communicate with the four retarding chambers 32 via four oil passages 36 penetrating through the boss member 21 in the radial direction. Lock pin 27
The lock hole 8c of the intake cam sprocket 8 to which the head of
Communicates with one of the advance chambers 31 via an oil passage (not shown).

When no hydraulic oil is supplied to the advance chamber 31, the head of the lock pin 27 fits into the lock hole 8c of the intake cam sprocket 8 by the elastic force of the spring 28, and is shown in FIG. Thus, the intake camshaft 6 is locked in the most retarded state in which the intake camshaft 6 is rotated counterclockwise relative to the intake cam sprocket 8. When the hydraulic pressure of the hydraulic oil supplied to the advance chamber 31 increases from this state, the lock pin 27 is pressed against the resilience of the spring 28 by the hydraulic pressure of the hydraulic oil supplied from the advance chamber 31 so that the intake cam sprocket 8 Of the intake cam sprocket 8, the vane 21b is pushed by the hydraulic pressure difference between the advance chamber 31 and the retard chamber 32, and the intake camshaft 6 rotates clockwise relative to the intake cam sprocket 8. As the phase of the intake cam 11 with respect to 4 advances, the valve opening timing and the valve closing timing of the intake valve 13 change to the advanced side. Therefore, the advance chamber
By controlling the supply and discharge of hydraulic oil to and from the retard chamber 32 and the hydraulic pressure of the hydraulic oil in both chambers 31 and 32, the intake valve is controlled.
13 opening and closing timing can be changed steplessly.

Next, with reference to FIG. 4, a description will be given of the hydraulic oil passage and the control system of the switching mechanism 15 and the variable phase mechanism 20. Oil pumped by an oil pump 40 serving as a hydraulic pressure source from an oil pan 41 via an oil passage 42 is used as lubricating oil around the crankshaft 4 of the internal combustion engine 1 and a valve operating mechanism. It is discharged to the oil passage 43 as hydraulic oil. An oil passage 44 branched from the oil passage 43 and communicating with the switching mechanism 15 has a hydraulic switching valve for switching the oil pressure of the oil passage 44 between high and low.
46 are provided. The oil passage 45 branched from the oil passage 43 and communicated with the variable phase mechanism 20 includes an advance chamber 31 and a retard chamber.
The linear solenoid valve 50 is a hydraulic oil control means for controlling the supply and discharge of hydraulic oil to and from the hydraulic oil in both chambers 31 and 32.
Is provided.

On the other hand, the electronic control unit 47 is a control means for controlling the operation amount by driving a hydraulic switching valve 46 and the electromagnetic valve 50, an intake camshaft sensor for detecting the rotational position theta _I of the intake cam shaft 6 16 (see FIG. 1), a TDC sensor that detects the top dead center θ _TD of the piston 2 based on an exhaust cam shaft sensor 17 (see FIG. 1) that detects the rotational position of the exhaust cam shaft 7, and the rotational position of the crank shaft 4. crankshaft sensor 1 for detecting the theta _C
8 (see FIG. 1), an intake pressure sensor for detecting an intake pressure P, the cooling water temperature sensor for detecting a cooling water temperature T _W, a throttle opening sensor for detecting the throttle opening theta _TH, and the rotational speed Ne of the internal combustion engine 1 Each signal is input from a rotation speed sensor for detecting, an intake air temperature sensor for detecting the intake air temperature T _A , and a current amount detecting sensor for detecting the amount of current I supplied to the solenoid valve 50.

Furthermore, the electronic control unit 47, the target cam phase C _M that the rotational speed Ne and the intake pressure P and the parameter
Various maps and tables used when controlling the hydraulic switching valve 46 and the solenoid valve 50 are stored. Here, the valve train control device includes the phase variable mechanism 2
0, an electromagnetic valve 50, a hydraulic switching valve 46, a switching mechanism 15, an electronic control unit 47, an oil pump 40, and oil passages 43, 44, 45.

On the other hand, as shown in FIG. 5, the solenoid valve 50 has a cylindrical sleeve 51, a spool 52 slidably fitted inside the sleeve 51, and a spool 52 fixed to the sleeve 51. And a spring 54 for urging the spool 52 toward the electromagnetic coil 53. The operation amount of the solenoid valve 50 is determined according to the current amount I to the electromagnetic coil 53 which is controlled based on the duty ratio based on the ON duty of the energization signal output from the electronic control unit 47. The spool 52 moves against the elasticity of the spring 54 according to the duty ratio,
Its axial position is steplessly changed.

The sleeve 51 has a central inflow port 51a.
And an advance port 51b and a retard port 51c located on both sides thereof, and a pair of drain ports 51d and 51e located on both sides of both ports 51b and 51c. on the other hand,
The spool 52 has a central groove 52a, a pair of lands 52b and 52c located on both sides thereof, and both lands 52b and 52c.
And a pair of grooves 52d and 52e located on both sides of are formed. The inflow port 51a is connected to the oil pump 40,
The advance port 51b is connected to the advance chamber 31 of the variable phase mechanism 20, and the retard port 51c is connected to the retard chamber 32 of the variable phase mechanism 20. When current is not supplied to the solenoid valve 50, the spool 52 is biased by the spring 54,
The inflow port 51a communicates with the retard port 51c and the advance port 51
b is in a state of communicating with the drain port 51d.

Next, the operation of the variable phase mechanism 20 for supplying and discharging hydraulic oil by the solenoid valve 50 will be described. When the internal combustion engine 1 is stopped, the variable phase mechanism 20 is in a state where the retard chamber 32 has a maximum volume and the advance chamber 31 has a zero volume.
The lock pin 27 fits into the lock hole 8c of the intake cam sprocket 8, and is maintained at the most retarded state. When the internal combustion engine 1 starts, the oil pump 40 operates, and when the hydraulic pressure of the hydraulic oil supplied to the advance chamber 31 via the solenoid valve 50 exceeds a predetermined value, the lock pin 27 is disengaged from the lock hole 8c by the hydraulic pressure. Thus, the variable valve phase mechanism 20 becomes operable.

In this state, when the duty ratio of the energizing signal is increased from the set value of the neutral position, for example, 50%, the spool 52 moves to the left side of the neutral position against the spring 54 in FIG. The inflow port 51a connected to the pump 40 communicates with the advance port 51b via the groove 52a, and the retard port 51c communicates with the drain port 51e via the groove 52e. As a result, the phase variable mechanism 2
Hydraulic oil is supplied to the 0 advance chamber 31 and the hydraulic pressure rises, and the hydraulic oil is discharged from the retard chamber 32 and the hydraulic pressure decreases.
The intake camshaft 6 with respect to the intake cam sprocket 8
Are relatively rotated clockwise, and the cam phase of the intake camshaft 6 continuously changes to the advance side. When the target cam phase is obtained, the duty ratio of the energization signal is set to about 5
The spool 52 of the solenoid valve 50 is set to the neutral position shown in FIG. 5, that is, the inflow port 51a is connected to the pair of lands 52b and 52c.
The intake cam sprocket 8 and the intake camshaft 6 are closed by stopping at the positions where the retard port 51c and the advance port 51b are closed by the lands 52b and 52c, respectively.
And the cam phase can be kept constant.

In order to continuously change the cam phase of the intake camshaft 6 to the retard side, the duty ratio of the energization signal is reduced from 50%, the spool 52 is moved rightward from the neutral position, and connected to the oil pump 40. The inflow port 51a communicates with the retard port 51c via the groove 52a, and the advance port 51b
Through the groove 52d to the drain port 51d,
Hydraulic oil may be supplied to the retard chamber 32 of the variable phase mechanism 20 to increase the hydraulic pressure, and hydraulic oil may be discharged from the advance chamber 31 to reduce the hydraulic pressure. Then, when the target phase is obtained, the duty ratio of the energization signal is set to about 5
By setting the spool 52 to 0% and stopping the spool 52 at the neutral position shown in FIG. 5, the inflow port 51a, the retard port 51c, and the advance port 51b can be closed, and the cam phase can be kept constant.

Since the variable phase mechanism 20 is driven by the hydraulic oil, its behavior is affected by the oil temperature (temperature of the hydraulic oil). For example, since the viscosity of the hydraulic oil changes depending on the oil temperature, the hydraulic oil is applied to both the chambers 31 and 32 in order to form a hydraulic pressure difference between the advance chamber 31 and the retard chamber 32 of the variable phase mechanism 20. When the actual cam phase of the intake camshaft 6 approaches the target cam phase, the response is affected by the viscosity of the hydraulic oil. Therefore, it is preferable from the viewpoint of convergence or follow-up to the target value to change the operation of the phase variable mechanism 20 according to the oil temperature in the control gain in the feedback control described later. In addition, it is preferable to determine the operation mode of the phase variable mechanism 20 and to grasp the operation state in consideration of the oil temperature.

Accordingly, here, since the oil temperature is provided in the oil passage 45 without using an expensive oil temperature sensor, the electromagnetic valve 50 of the solenoid valve 50 which is under the influence of the oil temperature and reflects the oil temperature is used. The oil temperature is estimated based on the temperature index value of the coil 53.

The procedure for estimating the oil temperature will be described below with reference to FIGS. The flowchart in FIG. 6 shows an oil temperature estimation duty ratio output routine for outputting an oil temperature estimation energization signal to the solenoid valve 50 immediately after the start of the internal combustion engine 1 (cranking end). Is executed in the electronic control unit 47 every predetermined time.

First, in step S1, the hydraulic pressure of the working oil reaching the variable phase mechanism 20 after the start of the internal combustion engine 1 is completed is set, and the operation of the variable phase mechanism 20 is prohibited until the preparation for operation is completed. It is determined whether or not the operation inhibition timer T _S for which the time (for example, 3 seconds) has been set has timed out. If the time has not elapsed, in step S 2, the phase of the operation oil supplied to the retard chamber 32 is increased. Until the variable mechanism 20 occupies the position where the most retarded state is attained, is the zero point learning inhibition time t ₁ (for example, 2 seconds) for prohibiting the learning of the zero point of the phase variable mechanism 20 performed after the start-up completed? If not, step S
Proceeding to 3, when a delay time t ₂ (for example, 0.1 seconds) for avoiding detection of a current amount I to the electromagnetic coil 53 described later immediately after the start of the operation in which the state of the hydraulic oil is unstable has elapsed. Proceed to step S4.

In step S4, the set value of the duty ratio of the energization signal is set as the duty ratio D _T for oil temperature estimation in order to drive the solenoid valve 50 for estimating the oil temperature.
The energization signal having the temperature measurement duty ratio _DT is
It is output from the electronic control unit 47 as an energization signal for oil temperature estimation to the solenoid valve 50. At this time, while the energization signal of the oil temperature estimation duty ratio _DT is being output, the electromagnetic coil 53
, And the current amount I is detected by the current amount detection sensor. The means for outputting the energization signal of the oil temperature estimation duty ratio _DT set in step S4 is the oil temperature estimation energization signal output means.

The set value is, for example, a duty ratio of 55%.
From the oil passage 45 to the advance chamber 31 of the phase variable mechanism 20 through the oil passage 45, through a spool 52 made of a heat conductive material in contact with the flowing hydraulic oil at that time. ,
The temperature of the electromagnetic coil 53 of the solenoid valve 50 further reflects the oil temperature. On the other hand, with this set value,
The hydraulic pressure is such that the boss member 21 does not rotate relative to the housing 24, that is, the lock pin 27 does not separate from the lock hole 8c in the advance chamber 31, and the cam phase does not change. A hydraulic fluid is provided. Then, by setting the oil temperature estimated execution flag F _T to "1" at step S5, the routine ends.

On the other hand, in step S1, the operation inhibition timer T _S
If the time has elapsed, the process proceeds to step S6, in which the solenoid valve is moved to bring the actual cam phase closer to the target cam phase set with the intake pressure P and the rotation speed Ne as parameters.
A normal duty ratio calculation routine, which is another routine for calculating the duty ratio of the energization signal output to 50, is executed.

In step S7, the phase variable mechanism 20
After the operation prohibition is released, an oil temperature estimation execution condition determination routine, which is another routine for determining whether or not a condition for enabling oil temperature estimation, is satisfied. In this routine, if the feedback control of the variable phase mechanism 20 is permitted, the current amount I for maintaining the neutral position of the solenoid valve 50 is set to a predetermined value in order for the variable phase mechanism 20 to maintain the target cam phase. It is determined whether the current cam phase is within a predetermined range, the actual cam phase is within a predetermined range in the vicinity of the target cam phase, and the fluctuation of the rotation speed Ne is within a predetermined range. Oil temperature estimation
The flag _FT is set to "1", otherwise the oil temperature estimation execution flag _FT is set to "0". Thus, the oil temperature can be estimated even when the feedback control of the variable phase mechanism 20 is being performed.

Note that in both of these separate routines,
When the feedback control of the phase variable mechanism 20 is not permitted, the substantial processing of those routines is not performed,
Oil temperature estimation execution flag _FT is set to "0". Therefore, when the zero-point learning prohibition time t ₁ in step S2 has passed, and when the delay time t ₂ has not elapsed in step S3, the process proceeds to step S6 and step S7, the feedback control of the time variable phase mechanism 20 Is not permitted, the oil temperature estimation execution flag F _T is set to “0” without executing the processes of the duty ratio calculation and the oil temperature estimation execution condition determination.

In the process from step S2 to step S4, the oil temperature estimation duty ratio is output during the operation inhibition time of the variable phase mechanism 20 and during the zero point learning inhibition time to output the oil temperature estimation duty ratio. This is because the oil temperature can be estimated without affecting the operation of the variable phase mechanism 20. In addition, by estimating the oil temperature at an early stage after the start of the internal combustion engine 1 in a state where the operating oil is supplied to the variable phase mechanism 20 via the solenoid valve 50, the obtained estimated oil temperature is used as the variable phase mechanism. Over a wide operating range of the internal combustion engine, such as being used for the operation start condition of 20, or being able to control the phase variable mechanism 20 reflecting the oil temperature from an early stage after the start of the internal combustion engine,
This is because more accurate control that reflects the oil temperature of the phase variable mechanism 20 can be performed.

Next, an estimated oil temperature is calculated using the oil temperature estimation duty ratio _DT obtained in the oil temperature estimation duty ratio output routine and the detected current I to the electromagnetic coil 53. The procedure will be described. The flowchart of FIG. 7 shows an estimated oil temperature calculation routine, which is executed by the electronic control unit 47 at predetermined time intervals.

First, in step S11, it is determined whether or not a set time t ₃ (for example, 5 seconds) has elapsed from immediately after the start which may have a relatively large change in the oil temperature, and the set time t ₃ has elapsed. when there is no, the process proceeds to step S14 to set the moderation settings K _S is a coefficient immediately after completion of starting coefficients C _T in step S12. Also, when the set time t ₃ has elapsed, the process proceeds to step S14 to set the coefficient C _T moderation settings K _N is the coefficient of normal in step S13.

[0044] Here, the averaging coefficient C _T, in order to reduce the influence of large variations in the actual oil temperature for estimating oil temperature, for use in the calculation moderation of the estimated oil temperature at step S18 to be described later Since the state of the hydraulic oil immediately after the start is not stable, including the oil temperature, compared with the normal state, the set value K _S is larger than the set value K _N (for example, 3 times the set value K _N ). Times) is set.

In step S14, the oil temperature estimation execution flag F
_T is referred to, and when the oil temperature estimation execution flag F _T is “1”, the process proceeds to step S15, and until immediately before the start of the internal combustion engine 1,
In consideration of the state where the internal combustion engine 1 and the electromagnetic coil 53 of the electromagnetic valve 50 attached to the internal combustion engine 1 are placed (soak state), a process for more accurately estimating the oil temperature is performed. That is, the ambient temperature of the internal combustion engine 1 before the start of the start reflects the state in which the internal combustion engine 1 was placed immediately before the start, and affects the temperature of the electromagnetic coil 53. The temperature of the electromagnetic coil 53 immediately before the start of the internal combustion engine 1 depends on the temperature of the electromagnetic coil 53 that is affected by the oil temperature after the internal combustion engine 1 is started and the oil pump 40 is operated.
Affects temperature of 53.

[0046] Therefore, in order to reflect the temperature of the start-up just before the solenoid 53 to the estimated oil temperature is detected immediately after starting the engine 1 is started by the intake air temperature T _A is the intake air temperature sensor as the ambient temperature of the internal combustion engine 1 , as illustrated in Figure 8, the map showing the correspondence between the coil resistance equivalent value of the intake air temperature T _a and the electromagnetic coil 53, the coil resistance equivalent value at that intake air temperature T _a is retrieved, the initial coil Resistance equivalent value R
Set to _CI . Here, the value equivalent to the coil resistance is that the value obtained in step S16 to be described later is an electromagnetic coil value.
This is because it is equivalent to 53 electric resistance values.

Further, in step S15, as shown in FIG. 9, a map in which a coefficient corresponding to an estimated coil resistance equivalent value R described later is stored is searched, and the correction coefficient K _R
Is set as Since the estimated coil resistance equivalent value R, which will be described later, is proportional to the electric resistance value of the electromagnetic coil 53, that is, the temperature of the electromagnetic coil 53, the correction coefficient K _R becomes smaller as the degree of warm-up of the internal combustion engine 1 becomes smaller. Ie electromagnetic coil
As the electrical resistance value or the estimated coil resistance equivalent value R of 53 becomes smaller, the initial coil resistance equivalent value R _CI has a greater degree of influence. Therefore, it is set to “1.0” in order to evaluate the influence, and the warm-up is more since the degree of the influence of the initial coil resistance equivalent value R _CI is smaller advances, when the vicinity after the increase rate of the oil temperature has slowed decreases linearly, even after completion of warming up the oil temperature and substantially steady state When this happens, it is set to "0". Of course, this coefficient is appropriately set by an experiment or the like. If the influence of the initial coil resistance equivalent value R _{CI on} the estimated coil resistance equivalent value R can be evaluated, the change of the estimated coil resistance equivalent value R of the coefficient can be evaluated. The transition of the value with respect to is not limited to that shown in FIG. In the first loop of the estimated oil temperature calculation routine, since the estimated coil resistance equivalent value R has not been obtained, the correction coefficient K _R is “1.0”.
It is said.

The value obtained by multiplying the correction coefficient K _R by the initial coil resistance equivalent value R _CI is defined as the correction resistance equivalent value R _C. Here, the initial coil resistance equivalent value R _CI is the internal combustion engine 1
Indicates the value of the electric resistance value of the electromagnetic coil 53 in the state where the internal combustion engine 1 was placed immediately before the start of the operation, that is, the initial state, and indicates the estimated oil temperature in step S4 of the oil temperature estimation duty ratio output routine. This has an effect on the temperature of the electromagnetic coil 53 when the duty _DT is output, that is, the resistance value of the electromagnetic coil 53. Therefore, the correction resistance equivalent value R _C reflects the state when the solenoid valve 50 was placed immediately before the start of the internal combustion engine 1, and furthermore, the electric resistance of the electromagnetic coil 53 after the start of the internal combustion engine 1. The degree of involvement of the initial coil resistance equivalent value _{RCI in} the value is taken into consideration. Therefore, by using the correction resistance equivalent value _RC for oil temperature estimation, more accurate oil temperature estimation becomes possible.

In the subsequent step S16, the oil temperature estimation duty ratio is determined by the current amount I detected when the energization signal of the oil temperature estimation duty ratio _DT obtained in the oil temperature estimation duty ratio output routine is output. The corrected resistance equivalent value _RC obtained in step S15 is added to the value obtained by dividing the ratio D _T to obtain an estimated coil resistance equivalent value R of the electromagnetic coil 53.

Here, in general, the duty ratio of the energization signal and the amount of current I supplied under the energization signal of the duty ratio are in a proportional relationship, and the ratio between the duty ratio and the amount of current I is: It corresponds to the electric resistance value. The oil temperature estimation duty ratio _DT and the electromagnetic coil 5
The ratio with the amount of current I supplied to 3 reflects the electric resistance value of the electromagnetic coil 53.

Therefore, the oil temperature estimation duty ratio D _T
The estimated coil resistance equivalent value R, which is a ratio between the current value I and the current amount I, is a temperature index value indicating the electric resistance value of the electromagnetic coil 53, that is, the temperature of the electromagnetic coil 53 proportional to the electric resistance value.

In the following step S17, as shown in FIG. 10, a value obtained by searching a map showing the correspondence between the estimated coil resistance equivalent value R and the estimated oil temperature T is used as the estimated oil temperature T.
After that, the process proceeds to step S18. In step S18, in order to reduce the influence of the fluctuation of the current amount I, a smoothing calculation is performed using the previous value T (n-1) of the estimated oil temperature T,
At this time, as described above, in order to reduce the influence of the oil temperature fluctuation, an averaging coefficient including different set values K _S and K _N is used according to a lapse of time immediately after the start is completed. And
The obtained value is set as the current value T (n) of the estimated oil temperature T, and the estimated oil temperature T is updated in the next and subsequent loops. If the oil temperature estimation execution flag _FT is "0" in step S14, the routine ends, and in this case, the estimated oil temperature T obtained so far is held. Here, steps S15 and S
Means for executing a series of procedures consisting of 16, S17, S18
This is oil temperature estimation means.

Hereinafter, an example of using the estimated oil temperature T obtained in the estimated oil temperature calculation routine in controlling the variable phase mechanism 20 of the valve train control device will be described.

The flowcharts of FIGS. 11 and 12 are as follows.
Shows a target cam phase calculation routine for calculating the target cam phase C _M of the intake cam 11 to be used when the feedback control of the variable phase mechanism 20, this routine is executed at every predetermined time in the electronic control unit 47.

First, when it is determined in step S21 that the internal combustion engine 1 is starting (cranking), step S21 is executed.
Set time operation inhibition timer T _S for prohibiting the operation of the phase variable mechanism 20 immediately after completion of starting with 22 t ₄ (e.g., 3 seconds) is set, the target cam phase C _M is set to "0" in step S23, In step S24, the control permission flag F of the variable phase mechanism 20 indicating whether or not the operation of the variable phase mechanism 20 is permitted is set to "0", and the operation is prohibited.

After the start of the internal combustion engine 1 is completed, the operation prohibition timer T _S expires in step S25 until the time expires.
Proceeding to step S23 and step S24, the operation of the variable phase mechanism 20 is prohibited. When the operation prohibition timer T _S has timed out and three seconds have elapsed after the start is completed, step 26 is executed.
Proceed to. If a failure of the variable phase mechanism 20 or a failure of a sensor or the like has occurred in step S26, the process proceeds to steps S23 and S24, and the operation of the variable phase mechanism 20 is prohibited.

If no failure has occurred in step S26, the operation proceeds to step S27. In step S27, FIG.
As illustrated in order to set in accordance with operating configuration of the phase variable mechanism 20 to the estimated oil temperature T, the estimated oil temperature T is, the target cam phase C _M of the phase variable mechanism 20 is set to a predetermined fixed value Fixed control mode start estimated oil temperature T for starting fixed control mode
_H (for example, about −10 ° C.), and if it is determined that the temperature is lower than the predetermined value, the operation is prohibited.
Fixed control permission flag F _H indicating whether or not to permit the control in the fixed control mode of the phase variable mechanism 20 is set to "0" at step S29, the target cam phase C at step S23
_M is set to "0", and control is permitted in step S24.
The flag F is set to "0" and its operation is prohibited.

[0058] When the estimated oil temperature T in step S27 is judged to be a fixed control mode start estimated oil temperature T _H or more, the process proceeds to step S28, the estimated oil temperature T is, the target cam phase C of the phase variable mechanism 20 _It is determined whether or not _M is lower than a variable control mode start estimated oil temperature T _V (for example, about 30 ° C.) for starting a variable control mode in which the variable control mode is made variable in accordance with the intake pressure P and the rotation speed Ne. Is determined, the fixed control mode area is set, and the fixed control permission flag F is set in step S30.
_H is set to "1", and then, in step S31, the target cam phase _CM is set to a preset fixed value _CMH ,
In step S32, the control permission flag F is set to "1", and the feedback control of the variable phase mechanism 20 in the fixed control mode is permitted.

[0059] Further, when the estimated oil temperature T is judged to be variable control mode start estimated oil temperature T _V or more in step S28, becomes a variable control mode area, the fixed control permission flag F _H proceeds to step S33 It is set to "0" and the process proceeds to step S34. In step S34, it is determined whether or not the internal combustion engine 1 is in an idling operation.
Proceed to steps S23 and S24 to change the phase
Operation of 20 is prohibited.

[0060] If not idling at step S34, in step S35, the estimated oil temperature T whether high is determined than the set value T ₁ corresponding to the high oil temperature. When it is determined to be high, the process proceeds to steps S23 and S24, and the operation of the variable phase mechanism 20 is prohibited.

[0061] When the estimated oil temperature T is determined to be the set value T ₁ less in step S35, the process proceeds to step S36, the map of the target cam phase C _M which set the rotation speed Ne and the intake pressure P as a parameter There is retrieved, the value obtained by searching the targeted cam phase C _M.

In the following step S37, the target cam phase C _M
The absolute value of the deviation obtained by subtracting the value of the previous target cam phase C _M (n−1) from the previous value is compared with the limit value D _MC of the change amount of the cam phase,
When the absolute value of the deviation is smaller than the limit value D _MC, the process proceeds to step S38, the searched map value and the current target cam phase C _M (n).

As a result of the comparison in step S37, when the absolute value of the deviation is equal to or larger than the limit value D _MC , in step S39, C _M
The sign of −C _M (n−1) is determined, and if the sign is positive, the previous target cam phase C _M (n−1) is set in step S40 in order to change the cam phase stepwise to the advanced side. The value obtained by adding the limit value D _MC to the current target cam phase C _M (n) is used as the current target cam phase C _M (n). When the inequality in step S39 is not satisfied,
To vary in stages to the retard side the cam phase in step S41, the limit value D _MC from the previous target cam phase C _M (n-1)
Is set as the current target cam phase C _M (n).
Thereafter, in step S32, the control permission flag F is set to "1", and the feedback control in the variable control mode of the variable phase mechanism 20 is permitted.

As shown in FIG. 13, the estimated variable control mode start oil temperature T _V is the fixed control mode start estimated oil temperature T _H.
Is set to a higher temperature. Then, the estimated oil temperature T becomes
In a temperature range lower than the fixed control mode start estimated oil temperature T _H , the viscosity of the hydraulic oil is high, so that even if feedback control is performed, it is difficult to achieve good responsiveness and convergence to the target value. For this reason, the operation is prohibited.
Further, the estimated oil temperature T becomes the fixed control mode start estimated oil temperature _TH.
However, since it is in a temperature range lower than the variable control mode start estimated oil temperature T _V , the viscosity of the hydraulic oil is not as low as the viscosity of the hydraulic oil in the variable control mode range where responsiveness and convergence are required. In the fixed control mode range, the output and fuel consumption in a relatively wide load range and the rotation speed range are compared with the case where the operation is prohibited by the feedback control in the fixed control mode in which the target cam phase _CM is fixed.・ Improving exhaust emissions. In the variable control mode range, the output, the fuel consumption, and the exhaust emission in a wide load range and the rotation speed range are optimized by the feedback control in the variable control mode.

In the next example, the intake cam is
In the feedback control in the eleventh cam phase variable control mode, the estimated oil temperature T is used. 14 and 15 show a routine of this feedback control, and this routine is also executed by the electronic control unit 47 every set time.

[0066] First, no failure flag F _NG phase variable mechanism 20 is set to "1" at step S51, a normal phase variable mechanism 20, and the control permission flag F in step S52 is "1" have been set determining, when the phase variable mechanism 20 is in operation, in step S53, the target cam phase C _M calculated by the target cam phase calculation routine, the output of the intake cam shaft sensor 16 and the crankshaft sensor 18 The deviation D _{M from} the actual cam phase C, which is the actual cam phase, is calculated, and the actual cam phase C (n−1) in the previous loop and the actual cam phase C in the current loop are determined in step S54.
Difference D _C is calculated in the (n).

If the control permission flag F has changed from "0" to "1" in the subsequent step S55, that is, if the operation of the phase variable mechanism 20 has been switched from prohibition to permission in this loop. In step S56, the deviation D _M is compared with a first feedforward control determination value D1, for example, 10 ° corresponding to a crank angle. As a result, if the deviation D _M is larger than the first feed forward control determination value D1, the feed forward control flag F _FF is set to “1” in step S57, and the phase variable mechanism 20 that should be feedback controlled is fed back. Controlled.

That is, in step S58, the previous integral term D _I
(N-1) is set to "0", and in step S59, the solenoid valve
After the duty value D (n) in the current loop of the duty ratio of the energization signal output to 50 is set to the upper limit value D _H1 , in step S73, the duty ratio D _OUT of the solenoid valve 50 is changed to the current duty value D ( n). In the subsequent loop, the result of the determination in step S55 is NO and the result of the determination in step S60 is YES.
At 56, the deviation _DM and the first feedforward control judgment value D1
Are compared, and while the deviation D _M is large, step S5
After 7 through step S59, the process proceeds to step S73.

Therefore, if the deviation D _M between the target cam phase C _M and the actual cam phase C is large when the control of the variable phase mechanism 20 is started, the duty value D (n) will be increased during this state. By setting the upper limit value D _H1 which is a constant, the phase variable mechanism 20 is subjected to feedforward control. In this way, by continuing the feedforward control only while the convergence is concerned because the deviation D _M is large, it is possible to achieve both responsiveness and convergence.

In step S56, the deviation D from the beginning of the control is calculated.
If _M is equal to or lower than the first feedforward control decision value D1, or if the deviation D _M in the feed forward control mentioned above is equal to or less than the first feedforward control decision value D1, in step S61 of the phase variable mechanism 20 feeds forward control flag F _FF is set to "0", the flow proceeds to step S62. In step S62, the last integral term D
If _I (n-1) is "0", it sets the initial value of the previous integral term D _I (n-1) at step S63.

As shown in FIG. 16, the initial value is retrieved from a map using the estimated oil temperature T as a parameter. The initial value is set to be smaller as the estimated oil temperature T is lower. Thereby, the change of the cam phase at the time of low oil temperature where the viscosity of the hydraulic oil is large is made slow, and the target cam phase C _M
Overshooting can be suppressed, and the convergence to the target value can be improved.

In step S64, the deviation D _M (when the target cam phase C _M is greater than the actual cam phase C) is compared with a second feed forward control determination value D2 that is smaller than the first feed forward control determination value D1. As a result, if the deviation D _M between the two is large, the current duty value D (n) is set to the upper limit value D _H2 in step S65, and the duty ratio D _OUT of the energization signal to the solenoid valve 50 is set in step S73. This time is the duty value D (n).

Similarly, in step S66, the deviation D _M (when the target cam phase _CM is smaller than the actual cam phase C) is equal to the third feed forward control determination value whose absolute value is smaller than the first feed forward control determination value D1. Compared to D3.
As a result, if the deviation D _M between the two is large, step S6
After the current duty value D (n) is set to the lower limit value D _L2 at 7, the duty ratio D _OUT is set to the current duty value D (n) at step S73.

[0074] Thus, even after the deviation D _M at step S56 becomes equal to or less than the first feedforward control decision value D1, steps S64, S66 in the deviation D _M is the second and third feed forward control determining value D2, Until D3 or less, the current duty value D (n) is changed from the upper limit value D _H1 to the upper limit value D _H2 or the lower limit value D _L2 , and the feedforward control is continued, thereby achieving both responsiveness and convergence. Can be planned.

When the absolute value of the deviation D _M becomes sufficiently small by the above-described feedforward control and both steps S64 and S66 are not established, in step S68, the proportional term gain K _P ,
After the integral term gain K _I and the differential term gain K _V is calculated, the proportional term D _P, integral term D _I and differential term D _V is calculated by the following equations in step S69.

D _P = K _P * D _M D _I = K _I * D _M + D _I (n-1) D _V = K _V * D _{C In} step S 70, the current duty value D (n) of the PID feedback control is obtained. but is calculated as the sum of the proportional term D _P, integral term D _I and differential term D _V.

[0077] Here, a control gain of the feedback control at the time of variable control mode proportional term gain K _P, the integral term gain K _I and the differential term gain K _V, the deviation D _M of the absolute value of the code and deviation D _M Size, estimated oil temperature T and rotational speed N
Using e as a parameter, a proportional term gain K _P , an integral term gain K _I, and a differential term gain K for changing the phase to the advance side
Proportional term gain K _P , integral term gain K _I, and derivative term gain K for changing each control gain of _V and the phase to the retard side
Each control gain of _V is retrieved from the table.

For example, if the target cam phase _CM is the actual cam phase C
Deviate D _M than is positive is and when the magnitude of the deviation D _M is less than a predetermined value, as shown in Figure 17, to control the advance side, setting the estimated temperature T _2, the 1 set rotational speed Ne1 and each of the six regions which are divided by the second set rotational speed Ne2, suitable proportional to the variable control mode of the feedback control followability to the target cam phase C _M to change is required A table in which the term gain K _P , the integral term gain K _I, and the derivative term gain K _V are set is prepared, and these gains are changed according to the estimated oil temperature T and the rotation speed Ne.

Then, the deviation D _M is positive and the deviation D _M
Is larger than a predetermined value, the target cam phase C _M
Is smaller than the actual cam phase C, the deviation D _M becomes negative, and control to the retard side is required, and the magnitude of the absolute value of the deviation D _M is smaller than a predetermined value;
_M is negative, and by the magnitude of the absolute value of the deviation D _M corresponds in each case when more than a predetermined value, the same table and the table that is shown in Figure 17 is prepared, respectively, change target cam phase suitable control gain in the feedback control of the variable control mode to follow-up is required to C _M is set to be, so that changing has these gains in accordance with the estimated oil temperature T and rotation speed Ne .

In any of the above cases, when the estimated oil temperature T is low or when the rotation speed Ne is low,
Or the high viscosity of the hydraulic oil, by the pressure of the hydraulic oil is insufficient, since the followability to the target cam phase C _M is reduced, the proportional term gain K _P, the integral term gain K _I and the differential term gain K _V is , The higher the estimated oil temperature T, and the higher the rotational speed N
It is set so that the higher the value of e is, the larger the value is, so that appropriate follow-up and responsiveness according to each engine operating state can be obtained, and feedback control that prevents hunting is performed. I have.

The proportional gain K _P , the integral gain K _I, and the differential gain K _V , which are the control gains used in the feedback control in the fixed control mode set in step S31, are also variably controlled. Unlike control gain mode, consisting of a stable proportion term gain K _P having a value set from the viewpoint of holding the integral term gain K _I and the differential term gain K _V a fixed target cam phase C _M A table using, as parameters, the sign of the deviation D _M between the target cam phase C _M and the actual cam phase C in which each control gain is a fixed value C _MH , the magnitude of the absolute value of the deviation, the estimated oil temperature and the rotation speed Ne. A table similar to the table in FIG. 17 is provided.

Subsequently, in steps S71 and S72, a limit process for the current duty value D (n) is executed. That is, if the current duty value D (n) exceeds the upper limit value D _H3 in step S71, the upper limit value D _H2 is set to the current duty value D (n) in step S65, and the current duty value D (n) is set in step S72. If n) is less than the lower limit value D _L3 , the lower limit value D _L2 is set to the current duty value D (n) in step S67. Then, in step S73, the duty value D (n) is set as the duty ratio D _OUT of the energization signal and the target cam phase C _M
And in order to converge the deviation D _M of the actual cam phase C to "0", the phase variable mechanism 20 is feedback-controlled.

In step S51, the phase variable mechanism 20
Is in failure and the failure flag F _NG is set to “1”, the current duty value D
(N) is set to “0”, and the phase variable mechanism 20 is set to the most retarded state.

[0084] The control permission flag F in step S52 is not set to "0", when the operation of the phase change mechanism 20 is prohibited at step S75 feedforward control flag F _FF to "0" is set, is set at a previous integral term D _I (n-1) at step S76 is "0", after the current duty value D of the phase variable mechanism 20 (n) is set to the lower limit value D _L1 in step S77 The duty ratio D _{OUT of the} energization signal output to the solenoid valve 50 in step S73 is set to the current duty value D (n).

In the following example, the estimated oil temperature T is used at the time of transition of the control mode of the variable phase mechanism 20, that is, at the time of transition between the fixed control mode area and the variable control mode area.

For example, when shifting from the fixed control mode to the variable control mode in accordance with a change in the estimated oil temperature T accompanying a change in the operating state of the internal combustion engine 1, immediately after the shift, FIG.
The same processing as the processing in steps S37 to S41 in the variable control mode described with reference to the flowchart of FIG. 12 is performed.

[0087] That is, only immediately after the transition from the fixed control mode to the variable control mode (this time, for example, fixed control mode flag F _H can be detected as the point at which changes from "1" to "0"), intake air pressure P and the absolute value of the previous target from the target cam phase C _M retrieval from a map in which the rotational speed Ne as parameters cam phase C _M (n-1) is subtracted deviation is compared with the limit value D _MT cam phase, the deviation Is smaller than the limit value D _MT , the target cam phase C
Let _M be the current target cam phase C _M (n).

When the absolute value of the deviation is equal to or _larger than the limit value D _MT , if the equation: C _M -C _M (n-1) is positive, the cam phase is gradually changed to the advance side. Therefore, the value obtained by adding the advance angle limit value D _MTA to the advance angle side to the previous target cam phase C _M (n-1) is set as the current target cam phase C _M (n). Further, if the above equation is “0” or negative, the previous target cam phase C is set so as to gradually change the cam phase to the retard side.
A value obtained by subtracting the retardation limit value D _MTR to the retard side from _M (n-1) is defined as the current target cam phase C _M (n).

As shown in FIG. 18, the limit value D _MT is retrieved from a map using the estimated oil temperature T as a parameter, and similarly, the advance side limit value D _MTA and the retard side limit value D _MTR also _uses the estimated oil temperature T as a parameter,
8 is searched from each map similar to the map of FIG.
Each of these limit values is set to be smaller as the estimated oil temperature T is lower, whereby the change of the cam phase at the time of low oil temperature where the viscosity of the hydraulic oil is large, Overshoot from the value can be suppressed, and the convergence to the target value can be improved.

[0090] Thus, when during the transition of the control mode of the feedback control, the deviation between the map retrieved target cam phase C _M and the previous target cam phase C _M (n-1) is large, once the target cam phase C By gradually switching _M with a smaller target value instead of switching, it is possible to prevent overshoot in control due to a sudden change in cam phase and a sudden change in engine output.

Further, the estimated oil temperature T is changed to the target cam phase C _M
It can also be used to determine the execution condition when detecting an abnormality of the phase variable mechanism 20 from the followability of the actual cam phase C with respect to. In this case, first, it is determined whether or not the estimated oil temperature T is within a predetermined temperature range determined by the lower limit and the upper limit. This temperature range is a temperature range in which the viscosity of the hydraulic oil is at an appropriate value in consideration of the fact that the viscosity of the hydraulic oil also affects the ability to follow the target value. The temperature is around 60 ° C, the upper limit is the actual oil temperature is 10
The estimated oil temperature T is set to about 0 ° C.

When it is determined that the estimated oil temperature T is within the above temperature range, the actual cam phase C is changed to the target cam phase _CM.
Whether the headroom value within the allowable range of the upper limit value obtained by adding the above lower limit obtained by subtracting a lower margin value and the target cam phase C _M is determined from the. Then, when the actual cam phase C is less than the lower limit, or when the value exceeds the upper limit value, it is determined that the actual cam phase C does not follow with a target cam phase C _M, if this state continues for a predetermined time An alarm is issued by turning on a lamp. In this way, by using the estimated oil temperature T as the execution condition of the abnormality detection, it is possible to perform the abnormality detection with high accuracy.

Hereinafter, the effects of the embodiment configured as described above will be described. Steps S15, S16, S17, S
An electromagnetic valve 50 that controls the supply and discharge of hydraulic oil to and from the hydraulic variable phase mechanism 20
Is obtained based on the estimated coil resistance equivalent value R, which is the temperature index value of the electromagnetic coil 53, an expensive oil temperature sensor is not required, and the cost of the valve train control device can be reduced.

Further, the solenoid valve 50 having the spool 52 provided in the oil passage is directly under the influence of the oil temperature since it is always in contact with the hydraulic oil at the time of supply and discharge. The 50 electromagnetic coils 53 are also strongly affected by the oil temperature, and the oil temperature and the temperature of the electromagnetic coil 53 have a strong correlation. Therefore, the estimated oil temperature T obtained based on the estimated coil resistance equivalent value R, which is a value related to the temperature of the electromagnetic coil 53, reflects the temperature transition of the oil temperature more accurately than the conventional cooling water temperature. It will be.

The estimated coil resistance equivalent value R is determined by determining whether the energizing signal of the oil temperature estimating duty ratio D _T that determines the operation amount of the driven solenoid valve 50 and the energizing signal during the output of the energizing signal are set. And the amount of current I supplied to the electromagnetic coil 53. That is, the ratio between the oil temperature estimation duty ratio _DT and the amount of current I supplied to the electromagnetic coil 53 is equivalent to the electric resistance value of the electromagnetic coil 53,
Since it reflects the electric resistance value of the electromagnetic coil 53, it can be a temperature index value of the electromagnetic coil 53,
Moreover, there is a strong correlation between the temperature index value and the oil temperature. Therefore, it is possible to accurately estimate the oil temperature based on the energization signal for driving the electromagnetic valve 50 and the current amount I having a clear correspondence with the temperature of the electromagnetic coil 53 reflecting the oil temperature.

[0096] Further, the ratio of the estimated oil temperature duty ratio D _T and current I is corrected by the intake air temperature T _A is the ambient temperature of the internal combustion engine 1 in the starting immediately before. The intake air temperature T _A is maintained until the internal combustion engine 1 and the solenoid valve 50 until immediately before the start.
This reflects the state where the electromagnetic coil 53 is placed, and has an effect on the temperature of the electromagnetic coil 53. The temperature of the electromagnetic coil 53 immediately before the start of the internal combustion engine 1 also affects the temperature of the electromagnetic coil 53 placed under the influence of the oil temperature after the start of the internal combustion engine 1. Therefore, a more accurate estimated oil temperature can be obtained by using the temperature index value that takes into account the intake air temperature T _A immediately before the start of the internal combustion engine 1 that affects the temperature index value of the electromagnetic coil 53.

The oil temperature is estimated after the completion of the start of the internal combustion engine 1 and for the time during which the operation of the variable phase mechanism 20 is prohibited after the start of the stopped internal combustion engine 1 is started. Since it is executed during this time, the oil temperature can be estimated without affecting the operation of the phase variable mechanism 20. In addition, the obtained estimated oil temperature T can be used as an operation start condition of the phase variable mechanism 20, or the phase variable mechanism 20 reflecting the oil temperature can be controlled from an early stage after the start of the internal combustion engine 1 is completed. For example, over a wide operating range of the internal combustion engine 1, more accurate control reflecting the oil temperature of the phase variable mechanism 20 can be performed.

In the above embodiment, the phase variable mechanism 20
Is provided only on the intake camshaft 6, but the phase variable mechanism 20 is provided.
May be provided only on the exhaust camshaft 7 or may be provided on the intake camshaft 6 and the exhaust camshaft 7. further,
The variable valve operating characteristic mechanism is the variable phase mechanism 20, but may be a mechanism that changes valve operating characteristics such as the opening period of the intake valve 13 or the exhaust valve 14 and the lift amount.

[Brief description of the drawings]

FIG. 1 is an overall view of an internal combustion engine to which the present invention is applied.

FIG. 2 is a sectional view of a variable phase mechanism.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a conceptual diagram of an oil passage of a hydraulic oil and a control system.

FIG. 5 is a sectional view of a solenoid valve.

FIG. 6 is a flowchart of an oil temperature estimation duty ratio output routine.

FIG. 7 is a flowchart of an estimated oil temperature calculation routine.

FIG. 8 is a diagram showing a map for searching for a coil resistance equivalent value from an intake air temperature.

FIG. 9 is a diagram showing a map for searching for a coefficient from an estimated coil resistance equivalent value.

FIG. 10 is a diagram showing a map for searching an estimated oil temperature from an estimated coil resistance equivalent value.

FIG. 11 is a first branch diagram of a flowchart of a target cam phase calculation routine.

FIG. 12 is a second diagram of the flowchart of the target cam phase calculation routine.

FIG. 13 is a diagram illustrating an operation mode of a phase variable mechanism with respect to an estimated oil temperature.

FIG. 14 is a first partial view of a flowchart of feedback control in the variable control mode of the variable phase mechanism.

FIG. 15 is a first branch diagram of a flowchart of feedback control in the variable control mode of the variable phase mechanism.

FIG. 16 is a diagram showing a map for searching for an integral term initial value from an estimated oil temperature.

FIG. 17 is a diagram showing a control gain table.

FIG. 18 is a diagram showing a map for searching for a limit value from an estimated oil temperature.

[Description of Signs] 1 ... internal combustion engine, 2 ... piston, 3 ... connecting rod, 4 ... crankshaft, 5 ... drive sprocket, 6 ...
Intake cam shaft, 7: Exhaust cam shaft, 8: Intake cam sprocket, 9: Exhaust cam sprocket, 10: Timing chain, 11: Intake cam, 12: Exhaust cam, 13: Intake valve, 14: Exhaust valve, 15: Switching Mechanism, 16, 17, 18 ... sensor, 20 ... variable phase mechanism, 21 ... boss member, 22 ... pin, 23 ... bolt, 24 ... housing, 25 ... plate, 26 ... bolt, 27 ... lock pin, 28 ... spring, 29, 30 ... seal member, 31 ... advance chamber, 32 ... retard chamber, 33, 34, 35, 36 ... oil passage, 40 ... oil pump, 41 ... oil pan, 42, 43, 44, 45 ... oil passage , 46 ... hydraulic switching valve, 47 ... electronic control unit, 50 ... solenoid valve, 51 ... sleeve, 52 ... spool, 53 ... electromagnetic coil, 54 ... spring.

Continuing from the front page (72) Inventor Junichi Suzuki 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside of Honda R & D Co., Ltd. (72) Shun Masuda 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. F term in Honda R & D Co., Ltd. (reference) 3G018 AA05 AB07 AB17 BA33 BA36 CA12 DA58 DA60 DA73 DA74 EA02 EA17 EA18 EA21 EA23 EA33 FA01 GA04 GA07 GA09 GA18 GA40 3G084 AA03 BA23 CA01 CA02 DA01 DA02 DA05 DA07 DA08 DA10 EB EB EB EB14 EC06 FA02 FA11 FA20 FA33 FA38 3G092 AA01 AA11 DA01 DA09 DF04 DF09 DG05 DG09 EA09 EA13 EA14 EA17 EA22 EA28 EA29 EB02 EB03 EC02 EC05 EC07 EC08 FA01 FA06 FA15 FA24 FA50 FB03 FB06 GA01 GA02 HA03Z FA03 KK17

Claims (4)

[Claims] 1. A hydraulic valve operating characteristic variable mechanism for changing an operating characteristic of an engine valve, and an electromagnetic hydraulic oil control means having an electromagnetic coil for controlling supply and discharge of hydraulic oil to and from the valve operating characteristic variable mechanism. And control means for controlling the driving of the hydraulic oil control means; and oil temperature estimating means for estimating the temperature of the hydraulic oil based on the temperature index value of the electromagnetic coil. Valve control device. 2. The temperature index value is based on an energization signal output from the control means to the hydraulic oil control means and an amount of current supplied to the electromagnetic coil while the energization signal is being output. 2. The valve control apparatus for an internal combustion engine according to claim 1, wherein the value is obtained by the following. 3. The oil temperature estimating means estimates the temperature during an operation prohibition time of the variable valve operation characteristic mechanism after the start of the internal combustion engine is completed. 2. A valve operating control device for an internal combustion engine according to claim 1. 4. The dynamics of an internal combustion engine according to claim 1, wherein the temperature index value is a value corrected by an ambient temperature of the internal combustion engine immediately before starting. Valve control device.