JP3510073B2 - Engine valve timing control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for an engine suitable for variably controlling the opening / closing timing of an intake valve or an exhaust valve in accordance with the operating state of the engine.

[0002]

2. Description of the Related Art Generally, an engine valve timing control device which variably controls the opening / closing timing of an intake valve or an exhaust valve according to the operating state of an automobile engine is disclosed in, for example, Japanese Patent Laid-Open No. 6-2516. Are known.

A valve timing control system for an engine according to this type of prior art will be described with reference to FIGS. 7 to 14.

In the figure, reference numeral 1 denotes an engine crankshaft. The crankshaft 1 is rotatably provided on an engine body (not shown), and a small diameter pulley 1A is integrally attached to one end side thereof. Further, the crankshaft 1 is provided with a crank angle sensor 11, which will be described later, for detecting the rotational phase α thereof.

Reference numeral 2 is a drive shaft for transmitting the rotational driving force of the crankshaft 1 to the side of a camshaft 4 which will be described later.
The drive shaft 2 has an axis O1 -O on the engine body side.
The large-diameter pulley 2A of the drive shaft 2 is rotatably provided about 1 and is connected to the small-diameter pulley 1A of the crankshaft 1 via a timing belt 3, for example.

Reference numeral 4 denotes a camshaft for opening and closing an intake valve (not shown) provided in each cylinder of the engine. The camshaft 4 has an axis O1 on the engine body side.
It is rotatably provided around -O1 and its rotational phase β is detected by a cam position sensor 12 described later. When the camshaft 4 is rotationally driven by the crankshaft 1 via the drive shaft 2 and an eccentric disc 9 described later, etc., when the rotational phase β becomes a predetermined rotational phase determined according to the intake stroke of each cylinder. , Cams 4A, 4
The intake valves are opened and closed by A ,.

Reference numeral 5 designates the drive shaft 2 and the eccentric disc 9
A connecting plate which is provided on the other end side of the drive shaft 2.
Rotates integrally with. An engaging groove 5A extending in the radial direction is formed in the connecting plate 5, and an engaging pin 9A of the eccentric disc 9 is engaged with the engaging groove 5A.

Reference numeral 6 denotes another connecting plate provided on one end side of the camshaft 4, and an engaging groove 6A extending in the radial direction is formed in the connecting plate 6, and an eccentric disc 9 is formed in the engaging groove 6A. The engagement pin 9B is engaged.

Reference numeral 7 denotes an eccentric mechanism as a rotation phase varying means for changing the opening and closing timings of the intake valves. The eccentric mechanism 7 is, as shown in FIG. 8, a disc holder 8, an eccentric disc 9 and a control which will be described later. Shaft 1
0 and driving means such as an electromagnetic actuator (not shown).

The eccentric mechanism 7 decenters the center O2 of the eccentric disc 9 with respect to the center O1 of the camshaft 4 by an eccentric amount ε, whereby the rotational phase β of the camshaft 4 is rotated by the rotational phase α of the crankshaft 1. In contrast, relative changes are made as will be described later, and a phase difference Φ is generated between these rotational phases α and β.

Reference numeral 8 denotes a disk holder in which an eccentric disk 9 is rotatably accommodated. One end side of the disk holder 8 is an annular portion 8B swingably attached to the engine body side via a fixing pin 8A, and the annular portion 8B. It is composed of a pair of engaging claws 8C, 8C integrally formed on the other end side of the portion 8B.

Reference numeral 9 designates the drive shaft 2 and the cam shaft 4
FIG. 7 shows an eccentric disc connected to the eccentric disc. As shown in FIG.
And an engaging pin 9B projectingly formed on the other side surface. The engaging pins 9A and 9B are, as shown in FIG.
Are arranged at positions facing each other in the radial direction with the center O2 therebetween.

The eccentric disc 9 is a disc holder 8
Is accommodated rotatably about the axis O2-O2 in the annular portion 8B, and the engaging pins 9A and 9B are connected plates 5 and 6 respectively.
Are slidably engaged in the engaging grooves 5A and 6A. As a result, the drive shaft 2 and the cam shaft 4 are
The connecting plates 5 and 6 and the eccentric disc 9 are connected to each other, and in this state, the eccentric disc 9 is relatively displaceable between the connecting plates 5 and 6 in the radial direction of the camshaft 4 (drive shaft 2). .

Reference numeral 10 denotes a control shaft for making the eccentric disc 9 eccentric.
Is rotatably provided on the engine body side, and its cam 10
A is slidably disposed between the engaging claws 8C of the disc holder 8. And the control shaft 10
The cam 10 is rotated by the electromagnetic actuator or the like.
Through A, the disc holder 8 is swung together with the eccentric disc 9 around the fixing pin 8A as shown by the chain double-dashed line in FIG.

As a result, the eccentric mechanism 7 gives the eccentric disc 9 an eccentric amount ε according to the turning angle τ of the control shaft 10, and a phase difference Φ corresponding to the eccentric amount ε with respect to the rotation of the crankshaft 1. It is generated between the phase α and the rotation phase β of the camshaft 4.

Reference numeral 11 denotes a crank angle sensor which constitutes a phase difference detecting means together with the cam position sensor 12, and the crank angle sensor 11 when the rotational phase α of the crankshaft 1 reaches a predetermined rotational phase as shown in FIG. To detect this,
As shown in FIG. 13, the reference signal S1 is output as a detection signal.

Reference numeral 12 denotes a cam position sensor provided on the camshaft 4 side. The cam position sensor 12 detects this when the rotation phase β of the camshaft 4 reaches a predetermined rotation phase as shown in FIG. Then, as shown in FIG. 13, the reference signal S
2 is output as a detection signal.

In the crank angle sensor 11 and the cam position sensor 12, the camshaft 4 makes one revolution (360 °).
The reference signals S1 and S2 are output during the operation. When the eccentric mechanism 7 causes a phase difference .PHI. Between the crankshaft 1 and the camshaft 4, the reference signal S2 of the cam position sensor 12 is changed to, for example, FIG.
Based on the time T between the reference signals S1 and S2 'and the engine speed N by relative displacement from the position synchronized with the reference signal S1 of the crank angle sensor 11 by the phase difference Φ, as indicated by S2'. Phase difference Φ,

[0019]

[Formula 1] Φ = k × T × N (However, k is a constant).

On the other hand, the crank angle sensor 11 and the cam position sensor 12 are connected to a control unit (not shown) as a control means. The control unit measures the time T between the reference signals S1 and S2 'to detect the phase difference .PHI. Based on the equation (1), and based on the detected value, the rotation angle .tau. And the rotation angle τ of the control shaft 10 is feedback-controlled by operating the electromagnetic actuator.

The engine valve timing control device according to the prior art has the above-mentioned structure, and its operation will be described below.

First, the crankshaft 1 is driven by the engine.
When rotationally driven, the rotational driving force is transmitted to the drive shaft 2 via the timing belt 3 and is transmitted to the eccentric disc 9 via the connecting plate 5 and the engaging pin 9A of the eccentric disc 9. As a result, the eccentric disc 9
Rotates in the disc holder 8 in the direction of arrow A in FIG. 8, and this rotational driving force is applied to the engagement pin 9B of the eccentric disc 9.
Is transmitted to the camshaft 4 via the connection plate 6 and the camshaft 4 opens and closes the intake valves when the rotation phase β reaches a predetermined rotation phase.

When the control shaft 10 is rotated by the electromagnetic actuator when the opening / closing timing of the intake valve is changed, the eccentric disc 9 is moved between the connecting plates 5 and 6 in the radial direction of the cam shaft 4 as shown in FIG. Due to relative displacement, the axis O2 -O2 is eccentric from the axis O1-O1 of the camshaft 4 by an eccentric amount ε.

As a result, the rotational phase β of the camshaft 4 is displaced relative to the rotational phase α of the crankshaft 1 by the phase difference Φ, and the opening / closing timing of the intake valve opened / closed by the camshaft 4 depends on the phase difference Φ. Change,
By changing the phase difference Φ to a desired value, the opening / closing timing of the intake valve can be appropriately controlled.

That is, for example, as shown in FIG. 12, when the eccentric disc 9 is eccentric by the eccentric amount ε 1 (ε 1> ε), when the crankshaft 1 (drive shaft 2) reaches the rotational phase α, the eccentric disc 9 is rotated. 9 rotates about the center O2 by an angle .gamma., But at this time, the camshaft 4 is rotated around the center O1 by the engaging pin 9B of the eccentric disc 9, and its rotation phase .beta. Become.

The rotation phase α of the crankshaft 1
And a rotational phase β of the camshaft 4 have a phase difference Φ defined by the following equation.

[0027]

[Formula 2] Φ = α−β

As shown in FIG. 11, the characteristic line of the phase difference Φ has a waveform close to a sine wave having a cycle of one rotation (360 °) of the camshaft 4, and changes periodically according to the rotation phase β. To do. Further, the waveform of the phase difference Φ changes according to the eccentricity amounts ε and ε1 of the eccentric disc 9 as shown by characteristic lines 13 and 14.

Here, the phase difference Φ between the crankshaft 1 and the camshaft 4 corresponds to the eccentricity ε of the eccentric disc 9 (the rotation angle τ of the control shaft 10) as shown by the characteristic lines 13 and 14 in FIG. Therefore, by detecting the phase difference Φ, the rotation angle τ at which the control shaft 10 is actually rotated can be obtained.

On the other hand, a method of directly detecting the rotation angle τ of the control shaft 10 with a contact sensor such as a potentiometer may be considered, but the reliability of the valve timing control device is maintained in consideration of its durability and the like. Becomes difficult.

Therefore, in the prior art, the control unit detects the phase difference Φ based on the reference signals S1 and S2 from the crank angle sensor 11 and the cam position sensor 12, and the control shaft 10 actually rotates based on the detected value. The calculated rotation angle τ is calculated by a non-contact method. Then, the target value τ0 of the rotation angle τ of the control shaft 10 is calculated based on the engine speed, for example, and the control shaft 10 is feedback-controlled so that the calculated value of the rotation angle τ becomes the target value τ0.

[0032]

By the way, in the above-mentioned prior art, since the crankshaft 1 and the camshaft 4 are mechanically connected via the drive shaft 2 and the timing belt 3, etc., these connecting portions are connected. May cause rattling or bending of the timing belt 3.

When the timing belt 3 is bent as shown by the chain double-dashed line in FIG. 9, the rotational phase α of the crankshaft 1 is displaced from the rotational phase β of the camshaft 4 by a phase deviation θ. As shown in FIG. 13, the reference signal S1 of the crank angle sensor 11 is the reference signal S2 indicated by the two-dot chain line with respect to the reference signal S2 of the cam position sensor 12.
Relative displacement to the 1'position.

As a result, the time T'between the reference signals S1 'and S2' becomes longer than the time T'between the reference signals S1 and S2 'by the time Ts corresponding to the phase deviation .theta. On the basis of the above, the phase difference Φ detected by the equation 1 becomes a larger value than the phase difference Φ when the phase deviation θ is not generated (hereinafter, referred to as the normal phase difference Φ 0).

That is, as shown in FIG. 14, the characteristic line 15 of the phase difference Φ is larger than the characteristic line 16 of the normal phase difference Φ 0 generated by actually rotating the control shaft 10 by the phase deviation θ. When the rotation angle τ of the control shaft 10 is calculated based on this detected value,
A value different from the actual rotation angle τ will be calculated.

Therefore, in the prior art, the actual rotation angle τ
Since the control shaft 10 cannot be accurately feedback-controlled so that becomes the target value τ 0, it is difficult to appropriately change the opening / closing timing of the intake valve.

The present invention has been made in view of the above-mentioned problems of the prior art. Even if the detected value of the phase difference deviates from the normal phase difference, the present invention can accurately detect the normal phase difference from the detected value. It is an object of the present invention to provide a valve timing control device for an engine, which can be obtained by calculation and can perform feedback control while stabilizing the rotational phase difference varying means.

[0038]

In order to solve the above-mentioned problems, the present invention provides a crankshaft, a camshaft which is rotationally driven by the crankshaft and opens and closes a valve for intake or exhaust, and a camshaft for the valve. Rotation phase varying means for varying the rotation phase of the camshaft to produce a phase difference between the rotation phases of the crankshaft and the camshaft in order to change the opening / closing timing, and the crankshaft and the camshaft by the rotation phase varying means. A phase difference detecting means for detecting a phase difference generated between the phase difference detecting means and the phase difference detecting means, and a control means for feedback-controlling the rotation phase varying means based on at least the detection result of the phase difference by the phase difference detecting means. It is applied to the valve timing control device of an engine.

The feature of the configuration adopted by the invention described in claim 1 is that the control means sets the rotation phase of the camshaft to a predetermined first rotation phase or second rotation phase. Sometimes the phase difference detection means reads the first detection value and the second detection value, respectively , and the normal phase difference to be generated between the crankshaft and the camshaft. Phase deviation for phase difference and
Wherein the front and the phase difference calculation means for calculating, based on the latest detection value, than the most recent value detected by said reading means
For each detection value read by the reading means and the latest detection value
Phase deviation calculating means for calculating the phase deviation based on
The operation amount calculating means for calculating the operation amount of the rotation phase varying means from the normal phase difference by the phase difference calculating means, and the calculated value of the operation amount by the operation amount calculating means become a value corresponding to the target value. It is configured to include signal output means for outputting a control signal to the rotation phase varying means.

According to the above construction, when the rotational phase of the camshaft becomes the first rotational phase and the second rotational phase,
The phase difference between the crankshaft and the camshaft is read by the reading means as the first detection value and the second detection value, respectively, and the phase deviation calculation means detects the detection value by the reading means.
A means for reading the phase deviation displaced from the normal phase difference
Based on the previous detection value and the latest detection value read by
Can be calculated. Then, in the phase difference calculation means, phase deviation Starring
The normal phase difference due to the operation of the rotational phase varying means can be calculated based on the phase deviation by the computing means and the latest detected value . Accordingly , the operation amount calculating means can calculate the operation amount at which the rotation phase varying means is actually operated based on the calculated value of the normal phase difference calculated by the phase difference calculating means. It is possible to output a control signal to the rotational phase varying means so that becomes a value corresponding to the target value.

According to the second aspect of the invention, the first rotational phase is relative to the rotational position of the camshaft at which the regular phase difference becomes substantially zero during one revolution of the camshaft. To a rotational position shifted by a certain angle to the front side of the rotational phase, and the second rotational phase is shifted from the rotational position of the camshaft by the certain angle to the rear side of the rotational phase. Shifted rotational position and the phase
Deviation calculating means, the latest detection read I respectively by said reading means between said cam shaft is at least two rotations
Based on the value and the first and second detection values before it.
Then, the phase deviation is calculated.

[0042] Accordingly, a first rotational phase and second rotational phase, the phase difference of said normal is symmetrical in front side, rear side across the rotational position of the camshaft to be substantially zero rotation Can be set to position. In the phase deviation calculation means, the first
The detected value, one of the detection value one of the second detection value, twice seen reading <br/> while the camshaft is at least 2 rotates, the other based on one of the detected values of these two times An estimated value corresponding to the detected value can be estimated and calculated. Then, by setting the first rotational phase and the second rotational phase at symmetrical rotational positions as described above, when the detected value of the phase difference does not include the phase deviation with respect to the regular phase difference, The absolute value of the estimated value and the detected value of the other becomes substantially equal.
Therefore, the phase deviation calculation means uses this to perform a comparison calculation between the estimated value and the detected value of the other to obtain the first deviation .
Detected value, the second detected value and the phase deviation between the normal phase difference can be calculated, and the phase difference calculation means can calculate the phase deviation based on the calculation result .
The normal phase difference can be calculated.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

1 to 6 show an embodiment of the present invention. In this embodiment, the same components as those of the prior art are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 21 denotes a control unit which constitutes the control means of the valve timing control device for an engine according to this embodiment, and the control unit 21 is a storage area 21A comprising, for example, ROM, RAM, etc., as in the prior art. The crank angle sensor 11 and the cam position sensor 12 are connected to the input side thereof, and the electromagnetic actuator 22 described later is connected to the output side thereof.

In the memory area 21A of the control unit 21, a valve timing control processing program (see FIGS. 2 to 4), which will be described later, is rotated together with the control shaft 10 so as to rotate in accordance with the operating state of the engine. The target value τ 0 of the angle τ is stored as a characteristic map according to, for example, the engine speed and the basic injection amount. Further, the storage area 21A stores a calculation map for calculating the rotation angle τ of the control shaft 10 from the phase difference Φ between the crankshaft 1 and the camshaft 4 (more accurately, the normal phase difference Φ 0). Has been done.

Reference numeral 22 is an electromagnetic actuator for rotating the control shaft 10. The electromagnetic actuator 22 is composed of a linear stepping motor or the like, and responds to a drive signal output from the control unit 21 almost in the same manner as in the prior art. The control shaft 10 is rotated.

The engine valve timing control system according to the present embodiment has the above-described structure, and will be described with reference to FIG.
The operation will be described with reference to FIGS.

First, when the control unit 21 determines that the engine is in the operating state in which the valve timing control should be performed based on the engine speed or the like, it starts the valve timing control process shown in FIGS. 2 to 4. Then, in step 1, initial values θ (1) and θ (2) of the phase deviation θ (n) calculated in step 2 are initialized to zero. Note that the count value n (n = 1, 2, 3, ...) Is the rotational phase β of the camshaft 4 after the start of the valve timing control.
Is incremented by "1" every time the first and second rotational phases β1 and β2 described later are reached.

Next, in step 2, as in steps 11 to 27 described later shown in FIGS. 3 and 4, the phase difference Φ is read and calculated to calculate the rotation angle τ of the control shaft 10. The required normal phase difference Φ 0 is used as the calculated values A (n) and B (n + 1), and the detected value a of the phase difference Φ
It is obtained from (n) and b (n + 1) as described later.

Then, in step 3, the calculated values A (n) and B (n +) of the normal phase difference Φ 0 calculated in step 2 are calculated.
Based on 1), the rotation angle τ of the control shaft 10 is calculated from the calculation map or the like in the storage area 21A. Thereby, the rotation angle τ of the control shaft 10 actually rotated by the electromagnetic actuator 22 is obtained.

Next, at step 4, in order to perform feedback control of the control shaft 10, for example, a storage area 21A based on the engine speed and the basic injection amount, etc.
The target value τ0 for the rotation angle τ of the control shaft 10 is calculated from the characteristic map in the above, and the difference between the target value τ0 and the rotation angle τ of the control shaft 10 obtained in step 3 is set to a predetermined hysteresis value or less. The control amount of the electromagnetic actuator 22 required for this is calculated.

Then, in step 5, a drive signal corresponding to the control amount calculated in step 4 is output to the electromagnetic actuator 22, and the turning angle τ of the control shaft 10 is substantially set to the target value τ by the electromagnetic actuator 22.
Rotate to 0.

As a result, the rotational phase β of the camshaft 4
Is the rotation angle τ of the control shaft 10 (target value τ0
) Corresponding to the phase difference Φ corresponding to the rotational phase α of the crankshaft 1, and the camshaft 4 can open and close the intake valves at appropriate timings corresponding to the engine speed and the like.

Next, in step 6, it is judged whether or not the above-mentioned valve timing control is in an operating state in which it should be continued based on, for example, the engine speed, and when it is judged as "YES", steps 2 to 5 are executed. By repeating the above process, feedback control is performed so that the rotation angle τ of the control shaft 10 always becomes a value corresponding to the target value τ 0.

If "NO" is determined in step 6, it means that the condition for stopping the valve timing control is satisfied, for example, when the engine speed becomes high, so that the process proceeds to step 7. The valve timing control ends.

As a result, when the valve timing control is continued as described above, the phase difference Φ is the rotational phase β of the camshaft 4 as shown by the solid line in FIGS. 5 and 6, for example.
Changes periodically according to. 5 shows a case where feedback control is performed so that the maximum value (minimum value) of the phase difference Φ increases at a constant rate with respect to the rotation of the camshaft 4, and FIG. 6 shows the rotation angle τ of the control shaft 10. Is held at a constant angle.

The phase difference Φ detected at this time is, as described in the prior art, the regular phase difference Φ shown by the dotted line in FIG. 5 (FIG. 6) due to the bending of the timing belt 3 or the like.
The value is larger than 0 by the phase deviation θ (n). The regular phase difference Φ0 has a waveform substantially symmetrical with respect to the rotational phase β of the camshaft 4 about a zero point position P0 described later.

Next, referring to FIGS. 3 and 4, the phase difference Φ
The read calculation processing of will be described. Note that a (n),
b (n + 1) indicates the first detection value and the second detection value, and A
(N) and B (n + 1) are detected values a (n) and b (n + 1)
The calculated value of the regular phase difference Φ0 corresponding to However, the estimated values a (n-1), b (n), which are not located on the characteristic line of the phase difference Φ (regular phase difference Φ 0) in FIG.
It is assumed that A (n-1) and B (n) are each estimated and calculated as described below.

First, in steps 11 and 12 in FIG. 3, the first and second detection values a (n) and b (n +
In order to detect the timing of reading 1), it is determined whether or not the rotation phase β of the camshaft 4 has reached the first and second rotation phases β1 and β2. Here, the first and second rotational phases β1 and β2 are the camshafts in which the regular phase difference Φ0 shown by the dotted lines in FIGS. 5 and 6 is substantially zero during one rotation of the camshaft 4. The rotational position β is predetermined as a rotational position having a phase shifted by a fixed angle (for example, 90 °) to the front side and the rear side of the rotational phase β with respect to the rotational position of 4 (hereinafter referred to as the zero point position P0). °,
The first rotation phase β1 is set to the position of 90 °, and the second rotation phase β2 is set to the position of 270 °.

When the determination in step 11 is "YES", the rotational phase β of the camshaft 4 has reached the first rotational phase β 1, so the process proceeds to steps 13 to 19 to detect the detected value a (n). The calculated value A (n) is calculated.

If "NO" is determined in step 11, the process proceeds to step 12 to perform the second rotation phase β2 determination process. Then, in step 12, "YE
When it is determined to be “S”, the rotation phase β of the camshaft 4
Has reached the second rotation phase β2, the process proceeds to steps 20 to 27 in FIG. 4 and the calculated value B (n + 1) is calculated from the detected value b (n + 1). In step 12, "N
When it is determined to be “O”, the rotation phase β of the camshaft 4
The determination processing of step 11 and step 12 is repeated until becomes the rotation phase β1 or the rotation phase β2.

Here, the processing performed in steps 13 to 19 will be described by taking as an example the case where the waveform of the phase difference Φ changes as shown in FIG. 5, and in step 13, the rotational phase of the camshaft 4 is changed. When β reaches the first rotation phase β 1, the phase difference Φ calculated by the crank angle sensor 11 and the cam position sensor 12 from the equation 1 is used as the first detection value a.
Read as (n).

Next, at step 14, it is judged whether or not the count value n is 2 or less (n≤2), and if "NO" is judged, it is not the first reading of the detected value a (n), and thus step Go to 15.

Then, in step 15, this detected value b (n-1) is calculated in order to perform a comparison operation with the previously detected value b (n-1).
-1), the estimated value a (n-1) is converted into the detected value a
From (n) and the detected value a (n−2) two times before,

[0066]

[Equation 3] Estimate calculation as.

In this case, the estimated value a (n-1) is, as shown in FIG. 5, a straight line connecting the detected values a (n-2) and a (n) to t (n-1): It is a value internally divided by a ratio of t (n) (a value corresponding to the position of the rotation phase β2). Further, the time t (n) is an elapsed time from when the rotational phase β of the camshaft 4 reaches the previous rotational phase β2 (rotational phase β1) to when it reaches the current rotational phase β1 (rotational phase β2). The time t (n) is measured by the soft timer of the control unit 21 or the like.

The detected value a (n-2) is the calculated value A.
Deviate from (n-2) by the phase deviation θ (n-2),
Similarly, since the detected value a (n) is deviated from the calculated value A (n) by the phase deviation θ (n), the estimated value a (n-1) obtained based on these is the calculated value a (n). A (n-2), A
The phase deviation θ with respect to the estimated value A (n−1) obtained from the calculation similar to the formula 3 from (n)
Only (n) has a large value.

[0069]

## EQU00004 ## a (n-1) = A (n-1) +. Theta. (N)

In this case, it can be considered that the phase deviation θ (n) due to the bending of the timing belt 3 is almost constant in a minute time such that the camshaft 4 makes two revolutions. Therefore, the phase deviation θ (n ), Θ (n−1), θ (n−
By regarding 2) as an equal value, the above equation 4 can be derived.

Next, at step 16, the estimated value a (n-
In order to perform a comparison calculation with 1), the detection value b (n-1) read in step 20 when the rotation phase β of the camshaft 4 becomes the rotation phase β2 is read out after the processing in step 21.

Here, the detected value b (n-1) is deviated by the phase deviation θ (n) from the calculated value B (n-1) as in the case of the detected value a (n). However, the detected value b (n-
In 1), the positive and negative are inverted in step 21, so
The phase deviation θ with respect to the calculated value B (n-1) is expressed by the following equation.
The value becomes smaller by (n).

[0073]

## EQU00005 ## b (n-1) = B (n-1)-. Theta. (N)

The regular phase difference Φ0 has a substantially symmetrical waveform with the zero point position P0 as the center as described above, and the first and second rotational phases β1 and β2 have the zero point position P0.
Since it is set symmetrically with respect to, the calculated value A (n-
2), the absolute value of the estimated value A (n-1) obtained from A (n) corresponding to the second rotational phase β2 and the calculated value B (n-1) is as follows: Will be equal.

[0075]

## EQU6 ## A (n-1) = B (n-1)

As a result, the equation for calculating the phase deviation θ (n) based on the estimated value a (n-1) and the detected value b (n-1) can be calculated from the equations 4 to 6 below. Therefore, in step 17, the phase deviation θ
Calculate (n).

[0077]

[Equation 7]

Next, in step 18, the detected value a (n)
And the phase deviation θ (n), the calculated value A
(N) is calculated, and in step 19, the rotation angle τ of the control shaft 10 is calculated based on the calculated value A (n), and the process returns to step 3.

[0079]

## EQU00008 ## A (n) = a (n)-. Theta. (N)

When it is determined to be "YES" in step 14, it means that the count value n is 2 or less and the rotational phase β of the camshaft 4 reaches the rotational phase β1 for the first time after the start of the valve timing control. Step 15-
The process proceeds to step 18 without performing the process of 17, and the calculated value A is calculated using the phase deviation θ (n) initialized in step 1.
Initially calculate (n).

On the other hand, when the camshaft 4 further rotates and its rotation phase β reaches the second rotation phase β2,
In order to calculate the latest calculated value B (n + 1), the process moves from step 12 to step 20 shown in FIG. 4, and the same processing as steps 13 to 19 described above is performed.

Then, in step 20, the phase difference Φ is read as the detected value b (n + 1), and in step 21, the sign of this detected value b (n + 1) is inverted to obtain
b (n + 1) is treated as an absolute value.

Next, at step 22, it is judged whether or not the count value n is 2 or less. If it is judged "YES", it means that the first reading is carried out at the rotation phase β2. Initially calculate (n + 1). If it is determined to be “NO” in step 22, step 23
Move on to.

Then, in step 23, the estimated value b (n) corresponding to the previous detected value a (n) is replaced with the detected value b (n +
1) and the detected value b (n-1) of the previous two times are estimated and calculated by the same calculation as the equation (3).

Next, in step 24, the estimated value b (n)
The previous detection value a (n) is read to perform a comparison calculation with
In step 25, the phase deviation θ (n + 1) is calculated from the detected value a (n) and the estimated value b (n) by the same calculation as the equation (6).

Finally, in step 26, the calculated value B (n + 1) is calculated by adding the phase deviation θ (n + 1) to the detected value b (n + 1), and then the process returns to step 3 in step 27.

Even if the rotation angle τ of the control shaft 10 is held at a constant angle as shown in FIG. 6, the phase difference Φ is a value obtained by drifting by the phase deviation θ (n) with respect to the regular phase difference Φ 0. Therefore, by performing the same processing as in the case of FIG. 5 described above, the first and second detection values a
Calculated value A of the normal phase difference Φ 0 from (n), b (n + 1)
(N) and B (n + 1) can be calculated.

Thus, in this embodiment, the camshaft 4
From the first and second detection values a (n) and b (n + 1) that read the phase difference Φ when the rotation phase β of becomes the first and second rotation phases β1 and β2, respectively. The phase difference Φ 0 is calculated as the calculated values A (n) and B (n + 1), and the calculated value A
Feedback control is performed so that the rotation angle τ of the control shaft 10 calculated based on (n) and B (n + 1) becomes a value corresponding to the target value τ 0.

As a result, the detected values a (n), b (n +
Even if 1) includes the phase deviation θ (n) with respect to the regular phase difference Φ 0, these detected values a (n) and b (n +
Based on 1), the phase deviation θ (n) can be accurately calculated by the equation (7), and the calculated value of the phase deviation θ (n) is detected values a (n), b (n + 1) as shown in steps 18 and 26. ), The calculated values A (n), B (n + 1)
Can be calculated with high accuracy.

That is, the first and second rotation phases β1 and β2 are set 90 ° before and after the zero point position P0 of the camshaft 4.
Is set as a rotational position whose phase is shifted by only, and detection values a (n) and b (n
Since the calculation values A (n) and B (n + 1) are calculated based on +1), for example, the previous calculation is performed based on the detection value a (n) and the detection value a (n−2) of the previous time. Estimated value a (n-1) and corresponding detected value b (n-1)
The phase deviation θ (n) can be accurately obtained by using the fact that the absolute values of the estimated value A (n-1) and the calculated value B (n-1) are equal by performing a comparison calculation of and.

Therefore, according to this embodiment, even if the timing belt 3 is bent, for example, the phase difference Φ
Since the normal phase difference Φ 0 can be accurately calculated based on the detected value of, the rotation angle τ of the control shaft 10 can be calculated with high accuracy based on the calculation result, and the control can be performed based on the calculated value of the rotation angle τ. Shaft 10 (Eccentric mechanism 7)
Can be stably feedback-controlled.

Further, the crankshaft 1, the camshaft 4, the crank angle sensor 11 or the cam position sensor 12 is used.
Even if the erroneous assembly occurs during the assembling work, and the reference signals S1 and S2 of the crank angle sensor 11 and the cam position sensor 12 are out of synchronization from the beginning, the detected value of the phase difference Φ causes the normal phase difference Φ0. Can be accurately detected, and the accuracy of feedback control can be reliably prevented from deteriorating due to incorrect assembly or the like.

[0093] In the above embodiment, steps 13 and 20 of the program shown in FIGS. 2 to 4 shows a specific example of reading means, Step 1 8, 2 6 shows a specific example of a phase difference computation means Steps 15-17 and 23-25 are ranked
Together indicate to a specific example of the phase deviation calculation unit, a specific example of Step 3 is operated amount calculating means, step 4 and 5 shows a specific example of the signal output means, respectively.

Further, in the above embodiment, the rotational phase β, the phase difference Φ, etc. of the camshaft 4 temporally calculated by the reference signals S1, S2 of the crank angle sensor 11 and the cam position sensor 12 are based on the engine speed. However, the present invention is not limited to this. For example, the crank angle sensor 11 or the like outputs an angle signal every 1 ° to the control unit 21, and based on the angle signal, the rotation phase β or The phase difference Φ or the like may be directly detected as an angle.

Further, in the above embodiment, the valve timing control device for controlling the opening / closing timing of the intake valve is illustrated as the prior art, but the present invention is not limited to this, and either one of the intake valve and the exhaust valve or It may be applied to a valve timing control device that controls both opening and closing timings.

[0096]

As described in detail above, according to the first aspect of the invention, the reading means reads the camshaft when the rotation phase becomes the first rotation phase or the second rotation phase. The latest detected value and the phase calculated by the phase deviation calculation means
The phase difference calculation means calculates a normal phase difference based on the deviation, and the operation amount calculation means calculates the operation amount of the rotation phase variable means based on the normal phase difference, and the calculated value of the operation amount is calculated. Since the feedback control is adopted, even if the first and second detection values include the phase deviation with respect to the normal phase difference, this phase deviation is read with the latest detection value and the first detection value read before that. And the second detection value
Can be accurately calculated by the phase deviation calculation means based on
The normal phase difference can be accurately calculated based on the calculated value of the phase deviation by the phase deviation calculating means . Therefore, the operation amount of the rotation phase varying means can be calculated with high accuracy from the regular phase difference, and the rotation phase varying means can be stably feedback-controlled based on the calculated operation amount.

According to the second aspect of the invention, the first rotational phase and the second rotational phase are constant on the front side and the rear side with respect to the rotational position of the camshaft where the normal phase difference becomes zero. Set as a rotational position with the phase shifted by an angle and set the phase deviation.
Difference calculating means, from the configured camshaft for calculating the phase deviation based on the first and second detection value before the latest detection value and than read write during at least two revolutions, For example, read 2 while the camshaft rotates 2 times.
An estimated value corresponding to the second detected value can be estimated and calculated based on the first detected values of the batches, and the estimated value and the second detected value are compared and calculated so that when the phase deviation does not occur. The phase difference can be calculated by utilizing the fact that the estimated value and the detected value are substantially equal , and the phase difference calculating means is
A normal phase difference can be accurately calculated using the phase deviation .

[Brief description of drawings]

FIG. 1 is a block diagram showing a valve timing control device for an engine according to an embodiment of the present invention.

FIG. 2 is a flow chart showing a control process of valve timing control by a control unit in FIG.

FIG. 3 is a flowchart showing a phase difference reading calculation process in FIG.

FIG. 4 is a flowchart showing a phase difference reading calculation process subsequent to FIG. 3;

FIG. 5 is a characteristic diagram showing a change in phase difference with respect to a rotation phase of a camshaft.

FIG. 6 is a characteristic diagram showing a change in phase difference with respect to a rotation phase of a cam shaft in a state where a control shaft is held at a constant rotation angle.

FIG. 7 is a partially cutaway front view showing a valve timing control device for an engine according to a conventional technique.

8 is a cross-sectional view taken along the arrow VIII-VIII in FIG. 7 showing an eccentric disc together with a control shaft and the like.

9 is a right side view in FIG. 7 showing a crankshaft, a camshaft, a crank angle sensor, a cam position sensor and the like.

FIG. 10 is an explanatory view showing a state where the eccentric disc in FIG. 8 is eccentric with respect to the cam shaft.

11 is a characteristic diagram showing a change in phase difference with respect to a rotational phase of a camshaft according to an eccentric amount of an eccentric disc in FIG.

FIG. 12 is an explanatory view similar to FIG. 10, showing a state in which the eccentric disc is rotated by the drive shaft.

13 is a characteristic diagram showing reference signals output from the crank angle sensor and the cam position sensor in FIG. 9.

FIG. 14 is a characteristic diagram showing a state in which a phase deviation has occurred between the normal phase difference and the detected value of the phase difference.

[Explanation of symbols]

1 crankshaft 4 camshaft 7 Eccentric mechanism (rotational phase changing means) 9 Eccentric disc 10 control shaft 11 Crank angle sensor (phase difference detection means) 12 Cam position sensor (phase difference detection means) 21 Control unit (control means) α, β rotation phase β1 1st rotation phase β2 Second rotation phase Φ phase difference Φ 0 Normal phase difference a (n) First detection value b (n) second detection value A (n), B (n) Calculated value of regular phase difference θ (n) Phase deviation τ Rotation angle (working amount) τ0 target value

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02D 13/02 F01L 13/00 F02D 41/20 F02D 45/00 G05B 11/36

Claims (2)

(57) [Claims] 1. A crankshaft, a camshaft rotatably driven by the crankshaft to open and close an intake or exhaust valve, and a rotational phase of the camshaft to change the opening / closing timing of the valve. Rotational phase varying means for producing a phase difference between the rotational phases of the crankshaft and the camshaft, and a phase difference for detecting the phase difference produced between the crankshaft and the camshaft by the rotational phase varying means as a detection value. A valve timing control device for an engine, comprising: a detection means; and a control means for feedback-controlling the rotational phase varying means based on at least a phase difference detection result by the phase difference detection means, wherein the control means comprises the camshaft. first rotation position phase rotation phases of predetermined a second rotational phase First detection value from said phase difference detecting means when a read-free reading means of the second detection value, respectively, the phase difference between the normal to be generated between the crankshaft and the camshaft, position of the regular read the latest and the phase difference calculation means for calculating, based on the detected value, the reading means before the latest detected value of said reading means and the phase difference for phase difference
The phase based on each of the detected values and the latest detected value
A phase deviation calculating means for calculating a deviation; an operation amount calculating means for calculating an operation amount of the rotational phase changing means from the normal phase difference by the phase difference calculating means; and a calculated value of the operation amount by the operation amount calculating means. A valve timing control device for an engine, comprising: a signal output means for outputting a control signal to the rotation phase varying means so as to obtain a value corresponding to a target value. 2. The first rotation phase is a constant angle to the front side of the rotation phase with respect to the rotation position of the camshaft where the regular phase difference becomes substantially zero during one rotation of the camshaft. The rotational position with the phase shifted by an amount
The rotational phase, and the rotational position shifted the predetermined angle amount corresponding phase behind the rotational phase with respect to the rotational position of the camshaft, the phase deviation calculating means, wherein the cam shaft is at least two rotations The engine according to claim 1, wherein the phase deviation is calculated on the basis of the latest detection value read by the reading means and the first detection value and the second detection value prior to the latest detection value. Valve timing control device.