JP2003148179A - Control device of electromagnet-driven valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit deterioration of the precision in the position detection of an armature even when the output characteristic of a position sensor is changed while a valve is opened/closed after an engine is started. SOLUTION: An electronic control device 35 detects the position of the armature 26 connected to the valve 16 functioning as an intake valve or an exhaust valve of the internal combustion engine by the position sensor 25. The valve 16 is opened/closed by controlling the electrification to electromagnets 32 and 34 for applying the electromagnetic force to the armature 26 based on the position of the armature 26 detected by the position sensor 25. During the opening/closing operation of the valve 16 after the engine is started, the output values of the position sensor 25 corresponding respectively to the full-opened position and the full-closed position of the valve 16 are stored and modified one by one as reference values. Then, based on the stored and modified reference values, the relation between the output values of the position sensor 25 and the position of the armature 26 is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electromagnetically driven valve which opens and closes a valve functioning as an intake valve or an exhaust valve of an internal combustion engine by an electromagnetic force of an electromagnet.

[0002]

2. Description of the Related Art For example, as an intake valve or an exhaust valve of an internal combustion engine, an electromagnetically driven valve that is opened and closed by electromagnetic force may be used instead of a valve that is opened and closed based on rotation of a camshaft. ing. Such an electromagnetically driven valve includes a valve that functions as an intake valve or an exhaust valve, an armature that displaces integrally with the valve, a pair of springs that bias the armature toward a neutral position, and a pair of armatures that are arranged in the displacement direction of the armature. Equipped with an electromagnet.

In this electromagnetically driven valve, for example, the valve supported by both springs at the neutral position is displaced from the neutral position in the fully open or fully closed direction by applying an electromagnetic force to the armature. Due to this displacement, the valve is held in the fully open position or the fully closed position before the engine is started. When the valve is opened, the energization of the closing drive electromagnet is stopped, and the valve is displaced in the valve opening direction by the biasing force of the spring. From a place close enough to the open drive electromagnet,
The opening drive electromagnet is energized to adsorb and hold the valve in the fully open position. On the other hand, when the valve is closed, the energization of the opening drive electromagnet is stopped, and the valve is displaced in the valve closing direction by the urging force of the spring. When the armature is sufficiently close to the closing drive electromagnet, the valve closing electromagnet is energized to adsorb and hold the valve in the closed position.

By the way, the energization of the open drive electromagnet and the close drive electromagnet is controlled based on the position of the armature detected by the position sensor. This energization control needs to be performed with high accuracy so that the speed at which the armature or the valve is seated is sufficiently reduced to reduce the impact and the responsiveness is secured. For that purpose, it is necessary to ensure the detection accuracy of the position sensor. However, due to individual differences in position sensors (characteristic variations between individuals) and changes over time, the actual position of the armature and the output value of the position sensor do not match, and the position of the armature cannot be detected accurately, and control accuracy deteriorates. I have a problem to do.

Therefore, when the engine is started, the output values of the position sensor corresponding to the fully open position and the fully closed position of the valve are respectively stored as reference values, and the output value of the position sensor and the position of the armature are stored based on these reference values. A technique for correcting the relationship with is proposed (for example, Japanese Patent Laid-Open No. 2000-8895).
No. 2001-207876).

[0006]

However, the output characteristics of the position sensor change even during the opening / closing operation of the valve after the engine is started due to the drift due to temperature and the like. Therefore, in the technique described in the above publication that corrects only when the engine is started, even if the position of the armature can be accurately detected when the engine is started, the position detection accuracy of the armature may deteriorate during the valve opening / closing operation after starting. .

The present invention has been made in view of the above circumstances, and an object thereof is that even if the output characteristic of the position sensor changes during the valve opening / closing operation after the engine is started, that is the cause. An object of the present invention is to provide a control device for an electromagnetically driven valve capable of suppressing the deterioration of the position detection accuracy of.

[0008]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. In the invention according to claim 1, the position sensor detects the position of the armature connected to the valve functioning as an intake valve or an exhaust valve of the internal combustion engine, and energization of an electromagnet that applies an electromagnetic force to the armature, In a control device for an electromagnetically driven valve that controls the valve based on the position of the armature detected by the position sensor to open and close the valve, a fully open position of the valve and an open position of the valve during opening and closing of the valve after engine startup. Learning means for sequentially storing and updating the output value of the position sensor corresponding to the fully closed position as a reference value, and the output value of the position sensor and the armature based on the reference value stored and updated by the learning means. And a correction means for correcting the relationship with the position.

According to the above arrangement, the position of the armature connected to the valve is detected by the position sensor while the internal combustion engine is operating. The energization of the electromagnet is controlled based on the detected position of the armature. Then, due to this energization control, the electromagnetic force generated by the electromagnet acts on the armature, the armature and the valve are displaced, and the valve functions as an intake valve or an exhaust valve.

During the opening / closing operation of the valve after the engine is started, the learning means successively stores and updates the output values of the position sensors corresponding to the fully closed position and the fully opened position of the valve as reference values. Then, the correction means corrects the relationship between the output value of the position sensor and the position of the armature based on the reference value stored and updated by the learning means.

Therefore, due to temperature drift and the like,
Even if the output characteristic of the position sensor changes during the valve opening / closing operation after the engine is started, it is possible to suppress deterioration of the armature position detection accuracy.

According to a second aspect of the present invention, in the first aspect of the invention, the learning means is an average value of the output values of the position sensor during the valve closing holding period for holding the valve in the fully closed position. And the same average value is treated as the output value of the position sensor corresponding to the fully closed position of the valve, and is sequentially stored and updated as the reference value.

According to the above configuration, when the reference value is stored and updated by the learning means, the average value of the output values of the position sensor during the valve closing holding period is obtained, and this average value is set to the fully closed position of the valve. It is treated as the output value of the corresponding position sensor,
It is sequentially stored and updated as a reference value. Therefore, even if noise is superimposed on the output signal of the position sensor, when the reference value is sequentially stored and updated, the influence of the noise on the reference value can be reduced.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the learning means is configured such that when the valve opening holding period for holding the valve at the fully open position is a normal length, Obtaining an average value of the output values of the position sensor during the open valve holding period, treating the average value as the output value of the position sensor corresponding to the fully open position of the valve, and sequentially storing and updating the reference value. Suppose there is.

According to the above arrangement, when the reference value is stored and updated by the learning means, if the valve opening holding period has a normal length, the average value of the output values of the position sensor during the valve opening holding period is The obtained average value is treated as the output value of the position sensor corresponding to the fully opened position of the valve, and is sequentially stored and updated as the reference value. Therefore, even if noise is superimposed on the output signal of the position sensor, when the reference value is sequentially stored and updated, the influence of the noise on the reference value can be reduced.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the learning means is configured to, when the valve opening holding period for holding the valve in the fully open position is shorter than a normal length. During the valve opening operation of the valve, the output value of the position sensor corresponding to the fully open position of the valve is obtained based on the extreme value of the output value of the position sensor, and is sequentially stored and updated as the reference value. .

According to the above arrangement, when the reference value is stored and updated in the learning means, if the valve opening holding period is shorter than the normal length, the extreme value of the output value of the position sensor is increased during the valve opening operation of the valve. Desired. Further, the output value of the position sensor corresponding to the fully opened position of the valve is obtained based on this extreme value, and the same value is sequentially stored and updated as the reference value. Therefore, when the valve opening holding period is shorter than the normal length, the number of output values obtained is small, and it is difficult to set a highly accurate reference value even if the average value of the output values is calculated. As described above, by obtaining the output value of the position sensor corresponding to the fully opened position of the valve based on the extreme value, it is possible to set and update the highly accurate reference value.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the learning means includes the position corresponding to the fully opened position of the valve when the valve opening holding period is shorter than a normal length. Regarding the output value of the sensor, it is assumed that a weighted average of the extremum obtained last time and the extremum obtained this time is obtained to obtain the output value of the position sensor corresponding to the new fully opened position of the valve.

According to the above arrangement, when the reference value is stored and updated by the learning means, if the valve opening holding period is shorter than the normal length, the output value of the position sensor corresponding to the previously obtained fully opened position of the valve. And the extreme value of the output value of the position sensor corresponding to the fully opened position of the valve obtained this time are weighted and averaged. Then, the output value of the position sensor corresponding to the fully opened position of the valve is obtained based on the obtained weighted average value, and the same value is sequentially stored and updated as the reference value. Therefore,
Even if noise is superimposed on the output signal of the position sensor, the influence of the noise on the reference value can be reduced when the reference value is sequentially stored and updated.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in an electromagnetically driven valve that opens and closes an intake valve or an exhaust valve of an internal combustion engine by electromagnetic force will be described with reference to the drawings.

As shown in FIG. 1, a cylinder head 11 of an internal combustion engine is provided with a port 13 which forms a part of an intake passage or a part of an exhaust passage and communicates with a combustion chamber 12. A valve seat 14 is provided at the end of the port 13 on the combustion chamber 12 side. Cylinder head 11
A valve guide 15 is mounted on the cylinder head 11 so that the valve stem 16 a can move the cylinder head 11 a.
On the other hand, it is slidably supported in the axial direction (vertical direction in FIG. 1). A valve body 16b is provided at the end of the valve stem 16a on the combustion chamber 12 side (the lower end in FIG. 1). And by these valve stem 16a and valve body 16b,
A valve 16 that functions as an intake valve or an exhaust valve is configured. The port 13 is brought into conduction (valve open) with the combustion chamber 12 as the valve body 16b moves away from the valve seat 14 as the valve 16 moves downward. Also,
When the valve body 16 b is seated on the valve seat 14 as the valve 16 moves upward, the port 13 becomes
Is closed (valve closed).

In the valve stem 16a, the combustion chamber 12
A lower retainer 18 is attached in the vicinity of the end portion (upper end portion in FIG. 1) on the side opposite to. A lower spring 19 is arranged in a compressed state between the cylinder head 11 and the lower retainer 18 and around the valve stem 16a, and the lower spring 19 causes the valve 16 to close in the valve closing direction (upward in FIG. 1). Is always urged.

An armature stem 21 is arranged coaxially with the valve stem 16a. Armature stem 2
An uptake retainer 22 is attached to an end portion (upper end portion in FIG. 1) opposite to the first valve stem 16a. An upper cap 23 is fixed to the cylinder head 11 via a casing (not shown). Upper cap 2
An upper spring 24 is arranged in a compressed state between 3 and the upper retainer 22. The upper spring 24 constantly urges the upper retainer 22 toward the valve stem 16a. The biasing direction of the upper retainer 22 by the upper spring 24 is the same as the valve opening direction of the valve 16 (downward in FIG. 1).

A position sensor 25 is attached to the upper cap 23. The position sensor 25 outputs a voltage signal that changes according to the distance between the sensor 25 and the upper retainer 22. Therefore, the amount of displacement of the armature stem 21 or the valve stem 16a, in other words, the amount of lift of the armature 26 or the valve 16 described later, is calculated based on the value corresponding to this voltage signal (output value lift (i) of the position sensor 25). Can be detected. In this embodiment,
The output value lift (i) becomes minimum when the valve 16 is fully opened, increases as the upper retainer 22 moves upward (in the valve closing direction) and approaches the position sensor 25, and becomes maximum when fully closed.

An armature 26 made of a high magnetic permeability material is attached to a substantially central portion of the armature stem 21 in the axial direction. In the casing (not shown), an upper core 27 is fixed between the armature 26 and the upper retainer 22. Similarly, in the casing, a lower core 28 is fixed between the armature 26 and the lower retainer 18. The upper core 27 and the lower core 28 are made of a high magnetic permeability material.
The armature stem 21 is reciprocally supported by the upper core 27 and the lower core 28 via a slide bearing 29.

In the upper core 27, the armature 26
A groove 27a is formed on the surface (lower surface) opposite to, and the upper coil 31 formed of an electromagnetic coil is housed and held in the groove 27a. And these upper cores 27
Further, the upper coil 31 constitutes an electromagnet (electromagnet for closing drive) 32 for driving the valve 16 in the valve closing direction.

Similarly, a groove 28a is formed on the surface (upper surface) of the lower core 28 facing the armature 26, and the lower coil 33, which is an electromagnetic coil, is housed and held in the groove 28a. And these lower core 28
The lower coil 33 constitutes an electromagnet (opening drive electromagnet) 34 for driving the valve 16 in the valve opening direction.

The above-described internal combustion engine of this embodiment is not provided with the throttle valve for adjusting the intake air amount. The intake air amount is adjusted by changing the opening / closing timing (valve timing) of the intake valve instead of the throttle valve.

Coil 3 of each electromagnet 32, 34 described above
The energization of 1, 33 is controlled by an electronic control unit 35 that integrally controls various controls of the internal combustion engine. This electronic control unit 35 includes a CPU, a memory, and coils 31, 33.
In addition to the drive circuit that supplies the exciting current to the position sensor 25
Input circuit that takes in the detection signal of
An A / D converter for performing D / D conversion (both not shown) is provided. The energization control is performed based on the output signal of the crank angle sensor 36. The crank angle sensor 36 is provided in the vicinity of a crank shaft (not shown) that is an output shaft of the internal combustion engine, and a pulse signal (crank angle signal) is generated every time the crank shaft rotates by a constant angle (crank angle). Is output. Based on the crank angle signal, the electronic control unit 35 calculates the engine rotation speed, which is the rotation speed of the crankshaft, and the crank angle.

FIG. 1 shows the state of the valve 16 when a drive current is not supplied to any of the coils 31 and 33 and no electromagnetic force is generated in both electromagnets 32 and 34. In this state, the armature 26 is not attracted by the electromagnetic force of each electromagnet 32, 34, and each spring 1
It stands still at an intermediate position between the cores 27 and 28 where the biasing forces of 9 and 24 are balanced. Further, in this state, the valve body 16b
Is separated from the valve seat 14 and is in a half open state. Hereinafter, the position of the valve 16 in this state will be referred to as the "neutral position".

Next, the operation mode of the valve 16 which is driven to open and close by controlling the energization of the electromagnets 32 and 34 will be described. FIG. 2 shows a position sensor 25 in the case where the valve 16 is driven to open from the state of being held in the fully closed position and displaced to the fully opened position, and then further driven to be closed to be displaced from the fully opened position to the fully closed position again. 7 is a timing chart showing the temporal transition of the output value lift (i) of the.

In FIG. 2, during the period from the timing t0 to the timing t1, the holding current for holding the valve body 16b at the fully closed position is supplied to the closing drive electromagnet 32. The holding current is set to such a value that the armature 26 can be attracted to the closing drive electromagnet 32 and held in that state. Depending on the supply of holding current, armature 2
6 is attracted by the electromagnetic force of the closing drive electromagnet 32, abuts against the upper core 27 against the elastic force of the upper spring 24, and the valve element 16b is held in a state of being seated on the valve seat 14.

Next, at the valve opening timing (timing t1) of the valve 16, the valve 16 is closed for a period (timing t1 to t2) from that time until the valve 16 reaches the position on the valve closing side from the neutral position by a predetermined amount. Energization control for the driving electromagnet 32 is performed. In this period, armature 26
Is separated from the upper core 27 and the valve 16 is displaced in the valve opening direction by controlling the drive current to the closing drive electromagnet 32 so that the valve 16 (armature 26) is separated in the valve opening direction.

Then, when the valve 16 is displaced from the fully closed position by a predetermined amount (timing t2), from that time until the valve 16 reaches the position on the valve opening side by a predetermined amount from the neutral position (timing t2 to t3). ), The supply of the drive current to the closing drive electromagnet 32 and the opening drive electromagnet 34 is stopped.

After that, when the valve 16 is further displaced by the elastic force of the upper spring 24 or the like and reaches the position on the valve opening side by a predetermined amount from the neutral position (timing t3).
From that time until the valve 16 reaches the fully open position (timing t3 to t4), the energization control for the opening drive electromagnet 34 is performed. During this period, the valve 16 is ensured to reach the fully open position with a predetermined displacement speed,
The electromagnetic force for attracting the valve 16 in the valve opening direction is controlled by adjusting the drive current applied to the opening drive electromagnet 34.

When the valve 16 reaches the fully open position (timing t4), a holding current for holding the valve 16 in the fully open state is used for opening drive until a predetermined period elapses from that time (timing t4 to t5). It is supplied to the electromagnet 34. In response to this supply, the armature 26 is attracted by the electromagnetic force of the opening drive electromagnet 34, and the lower spring 1
While contacting the lower core 28 against the elastic force of 9,
The valve body 16b is held in a state of being most separated from the valve seat 14.

Next, when a predetermined period elapses after the valve 16 reaches the fully open position, a period from that time until the valve 16 reaches the position on the valve opening side by a predetermined amount from the neutral position (timing t5 to t6). The energization control for the opening drive electromagnet 34 is performed. In this period, armature 26
Is separated from the lower core 28 so that the valve 16 is displaced in the valve closing direction by controlling the drive current to the opening drive electromagnet 34 to control the valve 16 to be separated in the valve closing direction.

When the valve 16 is displaced from the fully open position by a predetermined amount (timing t6), from that time until the valve 16 reaches the position on the valve closing side by a predetermined amount from the neutral position (timing t6 to t7). The supply of the drive current to the closing drive electromagnet 32 and the opening drive electromagnet 34 is stopped.

After that, when the valve 16 is further displaced by the elastic force of the lower spring 19 or the like and reaches the position on the valve closing side by a predetermined amount from the neutral position (timing t7), the valve 16 is moved to the fully closed position from that time. During the period until reaching (timing t7 to t8), energization control for the closing drive electromagnet 32 is performed. In this period, the valve 16 must be sure to reach the fully closed position with a predetermined displacement speed,
The electromagnetic force for attracting the valve 16 in the valve closing direction is controlled by adjusting the driving current applied to the closing driving electromagnet 32.

When the valve 16 reaches the fully closed position (timing t8), the valve 16 is kept in the fully closed state from that time until the next opening drive timing (valve opening timing) arrives. The holding current is the closing drive electromagnet 32.
Will be supplied again.

In the following, the period from the time when the valve 16 reaches the fully closed position until the opening drive is started (the period before the timing t1 in FIG. 2 and the period after the timing t8) is " It is referred to as "valve closing period". Similarly, valve 16
After reaching the fully open position, the period (timing t4 to t5 in FIG. 2) until the closing drive is started is referred to as "valve opening period". In the internal combustion engine of the present embodiment in which the throttle valve is not provided and the intake air amount is adjusted by changing the opening / closing timing of the intake valve, the valve opening holding period is adjusted according to the required intake air amount. It
For example, when the required intake air amount is small, the open valve holding period of the intake valve is shortened.

In the present embodiment, the energization of the coils 31 and 33 of the closing drive electromagnet 32 and the opening drive electromagnet 34 described above is controlled based on the output value lift (i) of the position sensor 25. Hereinafter, a specific procedure for controlling the energization of the coils 31 and 33 will be described with reference to the flowcharts of FIGS. The flowcharts of FIGS. 4 and 5 show a valve driving routine that is performed when the valve 16 is opened and closed during the operation of the internal combustion engine among the processes executed by the electronic control unit 35. Further, the flowchart of FIG. 3 shows an initial drive routine that is executed to forcibly displace the valve 16 to the fully open position or the fully closed position prior to the valve drive routine. Both these routines are repeatedly executed at a predetermined timing, for example, every predetermined time.

In the initial drive routine shown in FIG. 3, the electronic control unit 35 first starts in step 110 to start the internal combustion engine by turning on the ignition switch (IG SW) shown in FIG.
It is determined whether 37 is turned on. If this determination condition is satisfied (IG SW: ON), step 120
At, it is determined whether or not the ignition switch 37 was off in the previous control cycle.

If this determination condition is satisfied (last time: OFF), in step 130, the valve 16 is forcibly displaced from the above-mentioned neutral (semi-open) position to the fully open position or the fully closed position as the initial drive processing. . For example, each coil 31, 3 of the closing drive electromagnet 32 and the opening drive electromagnet 34
3 is alternately energized, a resonance phenomenon is caused by the action of the springs 19 and 24 to increase the amplitude, and then the armature 26 is attracted to the upper core 27 or the lower core 28, and the valve 1
Hold 6 in the fully open or fully closed position. Then, after performing the processing of step 130, this initial drive routine is ended. If each of the determination conditions of steps 110 and 120 is not satisfied, the initial drive routine is ended without performing the process of step 130. Thus, in the initial drive routine, the valve 16 is displaced to the fully open position or the fully closed position only when the ignition switch 37 in the off state is turned on.

In the valve drive routine of FIG. 4, the electronic control unit 35 first determines in step 210 based on the crank angle by the crank angle sensor 36 whether or not it is time to open the valve 16. For example,
It is determined whether the actual crank angle detected by the crank angle sensor 36 is the same as the target value for opening the valve 16. The target value for the crank angle is calculated in another routine based on various parameters such as the engine rotation speed, accelerator opening, engine cooling water temperature and the like.

If the determination condition of step 210 is not satisfied (the valve opening timing is not reached), step 260
In the same manner as in step 210 described above, it is determined whether or not it is the timing for closing the valve 16 based on the crank angle.

If the determination condition of step 260 is not satisfied (neither the valve opening timing nor the valve closing timing), the routine proceeds to step 350 in FIG. In step 350, similarly to the processing of step 210, it is determined whether or not the lift amount measurement period is in progress based on the crank angle. As shown in FIG. 6, during the lift amount measurement period (timing t10 to t12), the valve 16 is in the vicinity of the fully open position during the period in which the valve 16 is displaced from the fully closed position to the fully open position and then returned to the fully closed position again. It is set based on the estimated period in which it is located. If this determination condition is satisfied (is the lift amount measurement period), the process proceeds to step 360.

In step 360, it is determined whether the valve open period is a normal length based on the operating state of the internal combustion engine at that time. This normal length is set, for example, based on an average length that is taken in a normal engine operating state, except when the load is small when the required intake air amount is small.

If the determination condition of step 360 is satisfied (the valve opening holding period is a normal length), it is determined in step 370 whether it is the valve opening holding period. For example, it is determined whether or not the actual crank angle by the crank angle sensor 36 is set in advance and is in a period in which the valve 16 is predicted to be in the fully open position. If this determination condition is not satisfied (not in the valve opening holding period), the valve drive routine is ended, and if it is satisfied (in the valve opening holding period), the process proceeds to step 380.

In step 380, the output value lift (i) of the position sensor 25 at that time is acquired as the value LIFTMIN (i) corresponding to the valve fully open position. Acquisition here means storing in memory. After performing the processing of step 380, the valve drive routine is ended. Therefore, by repeating the processing of step 380 during the valve open holding period, the same number of times LIFTMIN (i) as the number of times of repetition is stored in the memory.

On the other hand, if the determination condition of step 360 is not satisfied (the valve opening holding period is shorter than the normal length), the output value lift ( Perform the process to find the local minimum of i).

First, at step 390, the output value lift (i) of the position sensor 25 at that time is the minimum value liftmin at the previous time.
Determines if it is less than pre. Here, the previous minimum value liftminpre is the minimum value of the output values lift (i) measured up to the previous time during the lift amount measurement period, and the determination condition of step 390 is satisfied (liftminpre>
lift (i)) and the output value lift (i) have decreased compared to the previous measurement, so in step 400, the current output value lift (i) is stored and updated as a new previous minimum value liftminpre, The valve drive routine ends. If the determination condition of step 390 is not satisfied, the valve driving routine is ended without performing the process of step 400. Therefore, the previous minimum value liftminpre finally stored in the memory is the smallest value in the lift amount measurement period, that is, the minimum value.

In this way, when the valve opening holding period has a normal length, the output value lift (i) is acquired as the value LIFTMIN (i) corresponding to the fully open position. On the other hand, when the valve opening holding period is shorter than the normal length, the minimum value of the output value lift (i) during the valve opening operation is obtained.

On the other hand, if the determination condition of step 350 is not satisfied (not the lift amount measurement period), it is determined in step 410 based on the crank angle whether or not the valve closing period is being maintained. Then, if the determination condition of step 410 is satisfied (is the valve closing holding period),
In step 420, the output value lift (i) at that time
Is obtained as the value LIFTMAX (i) corresponding to the valve fully closed position. After performing the processing of step 420, the valve drive routine is ended. Therefore, the value of LIFTMAX (i), which is the same as the number of repetitions, is stored in the memory by repeating the process of step 420 during the valve closing holding period. On the other hand, if the determination condition of step 410 is not satisfied (not in the valve closing holding period), the valve driving routine is ended without performing the process of step 420 described above.

By the way, the above-mentioned step 210 of FIG.
In step 220, if the determination condition is satisfied (that is, the valve opening timing), the arithmetic mean is calculated according to the following equation (1) based on the value LIFTMAX (i) stored in step 220 described above. Calculate the average value LIFTMAXave, which is the value (also called the arithmetic average value). In equation (1), M is the stored number.

LIFTMAXave = {LIFTMAX (1) + LIFTMAX (2) + ...... + LIFTMAX (M)} / M (1) Then, in step 230, the average value LIFTMAXa
ve is a position sensor 25 corresponding to the fully closed position of the valve 16.
The memory is updated (learned) as the reference value LIFTMAX of.

Thus, during the valve closing holding period immediately before the valve opening timing, the output value lift (i) is sequentially stored in the memory as the value LIFTMAX (i) corresponding to the valve fully closed position (step 410). , 420). When the valve closing holding period ends and the valve opening timing comes (step 210), the average value LIFTMAXa of the large number of values LIFTMAX (i) stored so far is calculated.
ve is obtained, this average value LIFTMAXave is treated as the output value of the position sensor 25 corresponding to the fully closed position of the valve 16, and is stored and updated as the reference value LIFTMAX.

Next, at step 240, the output value lift (i) of the position sensor 25 is corrected on the basis of the above-mentioned reference value LIFTMAX and the corrected lift amount LIFT is calculated.
This correction is performed, for example, according to the following equation (2).

LIFT = {(lift (i) -LIFTMIN) / (LIFTMAX-LIFTMIN)}-LIFTFULL (2) In the above equation (2), LIFTMIN is the above-mentioned reference value LIFTMAX.
Is a reference value of the position sensor 25 corresponding to the fully open position of the valve 16. This will be described later. LIFTFULL is the actual lift amount (full lift amount) when the valve body 16b is displaced from the fully closed position to the fully opened position.

Subsequently, at step 250, the closing drive electromagnet 32 is driven so that the armature 26 is driven with a characteristic having a target speed corresponding to the corrected lift amount LIFT.
The valve 16 is opened by performing feedback control of the energization of the upper coil 31. After executing the processing of step 250, the valve drive routine is ended.

In step 260 described above,
If the determination condition is satisfied (the valve closing timing is reached), it is determined in step 270 whether or not the immediately preceding valve opening holding period has a normal length. This determination is performed in the same manner as step 360 described above. If this determination condition is satisfied (the valve opening holding period is a normal length), in step 280,
The value LIFTMI stored by the processing of step 380 described above
Based on N (i), the average value LIFTMINave, which is an arithmetic average value, is calculated according to the following equation (3). In the equation (3), N is the stored number.

LIFTMINave = {LIFTMIN (1) + LIFTMIN (2) + ... + LIFTMIN (N)} / N (3) Subsequently, in step 290, the average value LIFTMINa
ve is a position sensor 25 corresponding to the fully open position of the valve 16.
The memory is updated (learned) as the reference value LIFTMIN of
Go to step 300.

On the other hand, if the determination condition of step 270 is not satisfied (the valve opening holding period immediately before is shorter than the normal length), the process proceeds to step 320. In step 320, in the series of processes of steps 390 and 400 described above, the final previous minimum value liftminpre stored in the memory at the end of the lift amount measurement period, that is, the output value li.
Set the minimum value of ft (i) as the reference value LIFTMIN.

Subsequently, in step 330, it is determined whether or not the previous valve opening holding period was also short as in this time. In other words, it is determined whether or not the state in which the valve opening holding period is short continues. Then, if this determination condition is satisfied, in step 340, the previous reference value LI
Weighted average (weighted average) processing is performed based on FTMIN and the reference value LIFTMIN of this time, and the weighted average value is obtained. For example, set constants a and b that satisfy the condition of a + b = 1 and a> b, and set a · (previous reference value LIFTMIN)
+ B · (reference value LIFTMIN this time) is used as the weighted average value.
The calculated weighted average value is set as a new reference value LIFTMIN, and then the process proceeds to step 300.

Step 290, 330 or 34 described above
In step 300 after shifting from 0, the output value lift (i) is corrected according to the equation (2) to calculate the corrected lift amount LIFT. At the time of this calculation,
The reference value LIFTMIN obtained at 320 or 340 is used.

Then, in step 310, the open drive electromagnet 34 is moved so that the armature 26 is driven with a characteristic having a target speed corresponding to the corrected lift amount LIFT.
The valve 16 is closed by performing feedback control of the energization of the lower coil 33. After executing the processing of step 310, the valve drive routine is ended.

By the processing of steps 250 and 310, the armature 26 is driven at a high speed until the armature 26 moves from the one electromagnet 32 (34) to the other electromagnet 34 (32). , Ensure responsiveness. Further, the armature 26 has the other electromagnet 3
4 (32), the armature 26 can be brought into contact with the electromagnet 34 (32) at a sufficiently small speed to reduce the impact caused by the contact. Alternatively, the armature 26 can be stopped at a position immediately before it comes into contact with the electromagnets 32 and 34 and controlled so as to prevent a collision.

According to the above valve driving routine, the output value lift (i) of the position sensor 25 is fetched and the reference value LIFTMAX is acquired.
, LIFTMIN are updated as shown in FIGS. 2 and 6, for example. 2 shows a case where the valve opening holding period has a normal length, and FIG. 6 shows a case where the valve opening holding period is shorter than the normal length.

As shown in FIG. 2, in the valve closing maintaining period (period before timing t1 and period after timing t8), steps 210 → 260 → 350 → 410 →
Processing is performed in the order of 420 → return. By this series of processing, the output value li of the position sensor 25
ft (i) is taken in and the value corresponding to the valve fully closed position LIFT
Obtained as MAX (i). Further, when the valve opening holding period (timing t4 to t5) has a normal length, in the valve driving routine, steps 210 → 260 → 350 → 3.
Processing is performed in the order of 60 → 370 → 380 → return. Through a series of these processes, the output value lift (i) of the position sensor 25 is taken in every predetermined time and is acquired as the value LIFTMIN (i) corresponding to the valve fully open position.

When the valve closing holding period ends and the valve opening timing (timing t1) is reached, step 210 →
Processing is performed in the order of 220 → 230 → 240. By these series of processes, the average value LIFTMAXave of the values LIFTMAX (i) acquired during the valve closing holding period is obtained, and this is
It is stored as the reference value LIFTMAX of the position sensor 25 corresponding to the fully closed position of the valve 16. The output value lift (i) is corrected based on this reference value LIFTMAX and the like.

When the valve opening holding period ends and the valve closing timing (timing t5) comes, step 210 → 2.
The processing is performed in the order of 60 → 270 → 280 → 290 → 300. By the series of these processes, the average value LIFTMINave of the values LIFTMIN (i) acquired during the valve opening holding period is obtained, and this is stored as the reference value LIFTMIN of the position sensor 25 corresponding to the fully open position of the valve 16. It The output value lift (i) is corrected based on this reference value LIFTMIN.

Further, as shown in FIG. 6, when the valve opening holding period (timings t11 to t12) is shorter than the normal length, in the valve drive routine, steps 210 → 26.
The processing is performed in the order of 0 → 350 → 360 → 390 → 400 → return. Through a series of these processes, the previous minimum value liftminpre and the output value lift (i) of the position sensor 25 are compared to obtain the minimum value of the output value lift (i).

Then, the valve closing timing (timing t1
2), the steps 210 → 260 → 270 → 32
Processing is performed in the order of 0 → 330 → 300. By the series of these processes, the previous minimum value liftminpr stored in the memory at the end of the lift amount measuring period of the valve opening holding period is
e, that is, the minimum value of the output value lift (i) is set as the reference value LIFTMIN. Output value based on this reference value LIFTMIN, etc.
lift (i) is corrected.

According to this embodiment described in detail above, the following effects can be obtained. (1) During the opening / closing operation of the valve 16 after the engine is started, the position sensor 25 corresponding to the fully closed position and the fully opened position of the valve 16
The output value lift (i) of the reference value LIFTMAX, LIFTMIN respectively
Is sequentially updated (learned). Then, the output value lift (i) of the position sensor 25 is corrected based on these reference values LIFTMAX and LIFTMIN to obtain the same output value.
The relationship between lift (i) and the position of the armature 26 is corrected.

Therefore, the armature 26 is not affected by the individual difference of the position sensor 25 (variation of characteristics between individuals) and the change over time due to wear of each part of the electromagnetically driven valve.
The position of can be detected accurately. In addition, due to temperature drift and the like, the output characteristics of the position sensor 25 change during the valve opening / closing operation after the engine is started, and the actual position of the armature 26 and the output value lift (i) of the position sensor 25 are changed. Even if there is a gap, the armature 2
It is possible to prevent the position detection accuracy of 6 from deteriorating. As a result, the intake / exhaust valve can be opened / closed at an accurate timing.

(2) When updating (learning) the reference values LIFTMAX and LIFTMIN, if the valve opening holding period is a normal length, the output value lift (i) of the position sensor 25 during the valve opening holding period is changed. The average value LIFTMINave is obtained, and this value is treated as the output value of the position sensor 25 corresponding to the fully open position of the valve 16, and stored and updated as the reference value LIFTMIN. Also,
Output value lift of the position sensor 25 during the valve closing period
Obtain the average value LIFTMAXave of (i), and use this value for the valve 16
Is treated as an output value of the position sensor 25 corresponding to the fully closed position and is stored and updated as a reference value LIFTMAX.

Therefore, even if noise is superimposed on the output signal of the position sensor 25, the reference values LIFTMAX, LIFTMI
In storing and updating N, the reference values LIFTMAX,
The influence of noise on LIFTMIN can be reduced by the averaging process.

(3) Memory update (learning) of reference value LIFTMIN
At this time, if the valve opening holding period is shorter than the normal length, the output value lift of the position sensor 25 is lifted during the valve opening operation of the valve 16.
Find the local minimum of (i). Also, based on this local minimum,
The output value of the position sensor 25 corresponding to the fully open position of the valve 16 is obtained, and this value is stored and updated as the reference value LIFTMIN.

Therefore, when the valve opening holding period is shorter than the normal length, the number of output values lift (i) that can be taken in is small, and therefore even if the average value LIFTMINave is calculated, the reference value LIFTMIN is highly accurate. Is difficult to set. However, by obtaining the output value of the position sensor 25 corresponding to the fully open position of the valve 16 based on the extreme value as described above, it becomes possible to set and update the highly accurate reference value LIFTMIN.

Further, if the output value lift (i) is taken in for the same period for the crank angle in order to calculate the average value LIFTMINave in the same manner as in the case where the valve opening holding period has a normal length. , An incorrect value (output value lift (i) at a position other than the fully open position) was captured, and the reference value
The accuracy of LIFTMIN may decrease. However, in the present embodiment in which the reference value LIFTMIN is set based on the minimum value,
Such a problem does not occur.

(4) When storing the reference values LIFTMAX and LIFTMIN for a short period of time during which the valve opening holding period continues, the output value of the position sensor 25 corresponding to the previously obtained fully open position of the valve 16 and , The weighted average of the extreme value of the output value of the position sensor 25 corresponding to the fully opened position of the valve 16 obtained this time. Then, based on the obtained weighted average value,
The output value of the position sensor 25 corresponding to the fully opened position of the valve 16 is obtained, and this value is successively stored and updated as the reference value LIFTMIN.

Therefore, even if noise is superimposed on the output signal of the position sensor 25 and only the extreme value obtained this time is significantly different from the extreme value at the normal time, when the reference value LIFTMIN is sequentially stored and updated, the The weighted average processing can reduce the influence of noise on the reference value LIFTMIN.

The present invention can be embodied in another embodiment shown below. The present invention is also applicable to an internal combustion engine equipped with a throttle valve for adjusting the intake air amount.

In the above-described embodiment, the average values LIFTMINave and LIFTMAXave in the valve opening holding period and the valve closing holding period are obtained, and are set as the output values of the position sensor 25 corresponding to the fully open position and the fully closed position of the valve 16. On the other hand, the output value is set at the specified timing during the valve open and hold periods.
The lift (i) may be taken in and used as the output value of the position sensor 25 corresponding to the fully open position and the fully closed position of the valve 16.

The present invention is also applicable to an internal combustion engine in which the lift amount (stroke amount) of the intake / exhaust valve is changed according to the engine operating condition. In this type of internal combustion engine, the reference values LIFTMAX and LIFTMIN are not updated when the intake / exhaust valve has a small stroke amount and is operated in a mode in which the valve 16 is not displaced to the fully open position. To prevent the output value of the position sensor when the valve 16 is located at a position different from the fully open position from being updated by mistake as the reference value LIFTMIN, and thus to prevent the position detection accuracy of the armature 26 from decreasing. Is.

The timing of updating the reference values LIFTMAX and LIFTMIN may be changed. For example, the reference value LIFTMAX,
Both LIFTMIN may be updated immediately before the valve 16 is opened or closed.

The processing of steps 330 and 340 in FIG. 4 may be omitted. That is, even if the state in which the valve opening holding period is short continues, the reference value LIFTMIN set in the process of step 320 may be used to calculate the corrected lift amount LIFT, as in the case where the state does not continue.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment embodying the present invention.

FIG. 2 is a timing chart showing a temporal transition of the output value of the position sensor when the valve opening holding period has a normal length.

FIG. 3 is a flowchart showing an initial drive routine executed by the electronic control unit.

FIG. 4 is a flowchart showing a valve driving routine executed by an electronic control unit.

FIG. 5 is a flowchart showing a valve driving routine.

FIG. 6 is a timing chart showing the temporal transition of the output value of the position sensor when the valve opening holding period is shorter than the normal length.

[Explanation of symbols]

16 ... Valve, 25 ... Position sensor, 26 ... Armature,
32 ... Closed drive electromagnet, 34 ... Open drive electromagnet, 35 ...
Electronic control unit, lift (i)… Output value, LIFTMAXave, LIFTMI
Nave ... Average value, LIFTMAX, LIFTMIN ... Reference value.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideyuki Nishida             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Keiji Shieda             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F term (reference) 3G018 AB09 AB16 BA38 CA12 DA36                       DA41 DA66 EA21 EA22 EA33                       EA35 FA01 FA06 FA07 GA02                 3G084 BA23 CA01 DA04 EB17                 3G092 AA11 DA01 DA02 DA07 EC05                       FA06 GA01

Claims (5)

[Claims] 1. A position sensor detects the position of an armature connected to a valve that functions as an intake valve or an exhaust valve of an internal combustion engine, and the position sensor detects the energization of an electromagnet that applies an electromagnetic force to the armature. In an electromagnetically driven valve control device that controls the valve based on the detected position of the armature to open and close the valve, the valve is opened and closed while the valve is opened and closed after the engine is started. Learning means for sequentially storing and updating the corresponding output value of the position sensor as a reference value, and a relationship between the output value of the position sensor and the position of the armature based on the reference value stored and updated by the learning means. A control device for an electromagnetically driven valve, which comprises: 2. The learning means obtains an average value of output values of the position sensor during a valve closing holding period for holding the valve in a fully closed position, and the average value corresponds to the fully closed position of the valve. The control device for an electromagnetically driven valve according to claim 1, wherein the control value is handled as an output value of the position sensor, and is sequentially stored and updated as the reference value. 3. The learning means obtains an average value of the output values of the position sensor during the valve opening holding period when the valve opening holding period for holding the valve in the fully opened position has a normal length, The control device for an electromagnetically driven valve according to claim 1 or 2, wherein the average value is treated as an output value of the position sensor corresponding to a fully opened position of the valve, and is sequentially stored and updated as the reference value. 4. The learning means is based on an extreme value of an output value of the position sensor during an opening operation of the valve when a valve opening holding period for holding the valve in a fully opened position is shorter than a normal length. The control device for an electromagnetically driven valve according to claim 1 or 2, wherein an output value of the position sensor corresponding to a fully opened position of the valve is obtained and sequentially stored and updated as the reference value. 5. The learning means, when the valve opening holding period is shorter than a normal length, regarding the output value of the position sensor corresponding to the fully opened position of the valve, the extreme value obtained last time and the output value obtained this time. The control device for an electromagnetically driven valve according to claim 4, wherein an output value of the position sensor corresponding to a new fully opened position of the valve is obtained by performing a weighted average with the extreme value.