JPH10196422A - Valve timing controller for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately feedback-control a phase difference changing means by performing the correction of the phase difference when the phase difference to be generated between a crankshaft and a cam shaft caused by the manufacturing error is not accurately detected. SOLUTION: In a control unit 21 a crank angle sensor 11 and a cam position sensor 12 are connected to the input side, and an actuator 22 is connected to the output side. The control unit 21 reads the phase difference in a state where an eccentric mechanism has the operating amount on the minimum side as a first detected value, reads the phase difference in a state where it has the operating amount on the maximum side as a second detected value, and selects a characteristic map of the phase difference and the operating amount on the basis of the first and second detected values. The operating amount is calculated on the basis of the characteristic map, and the eccentric mechanism is operated by the actuator 22.

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 apparatus for an engine for variably controlling the opening and closing timing of an intake valve and an exhaust valve of an internal combustion engine.

[0002]

2. Description of the Related Art In general, a valve timing control device for variably controlling the opening / closing timing of an intake valve or an exhaust valve in accordance with the operating state of an automobile engine or the like is known from, for example, Japanese Patent Application Laid-Open No. 6-2516. Have been.

Therefore, referring to FIGS. 12 to 19,
This type of prior art engine valve timing control device will be described.

In FIG. 1, reference numeral 1 denotes a crankshaft of an internal combustion engine. The crankshaft 1 is provided on an engine body (not shown), and a small-diameter pulley 1A is integrally attached to one end thereof. Further, the crankshaft 1 is provided with a projection 1B for detecting the rotation phase α,
The protruding portion 1B is detected by a crank angle sensor 11 including an electromagnetic pickup type detector described later.

A drive shaft 2 transmits the rotational driving force of the crankshaft 1 to a camshaft 4 described later.
The drive shaft 2 has a center O1 -O
1 A large diameter pulley 2A of the drive shaft 2 is connected to a small diameter pulley 1A of the crankshaft 1 via, for example, a timing belt 3 so that the drive shaft 2 rotates while the crankshaft 1 rotates twice. One rotation.

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 is connected to the drive shaft 2 via an eccentric disk 9 described later. And drive shaft 2
Also, it is provided on the engine body side so as to be rotatable around the center O1-O1. The camshaft 4 is driven to rotate by the crankshaft 1 together with the drive shaft 2. When the rotation phase β reaches a predetermined rotation phase determined according to the intake stroke of each cylinder, the cams 4A, 4A,
Open and close the intake valves.

The camshaft 4 has its rotational phase β.
Are provided, and each of the protrusions 4B is detected by a cam position sensor 12 including an electromagnetic pickup type detector described later.

Reference numeral 5 denotes an eccentric disk 9
The connection plate 5 is provided on the other end side of the drive shaft 2 and is connected to the drive shaft 2.
And rotate together. An engagement groove 5A extending in the radial direction is formed in the connection plate 5, and an engagement pin 9A of the eccentric disk 9 is engaged with the engagement groove 5A.

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

Reference numeral 7 denotes an eccentric mechanism as a rotation phase variable means for changing the opening and closing timings of the intake valves. The eccentric mechanism 7 includes a disk holder 8, an eccentric disk 9 and a control shaft 10 which will be described later, for example. And an actuator (not shown) composed of a proportional solenoid or the like.

The eccentric mechanism 7 eccentricizes the center O2-O2 of the eccentric disk 9 with respect to the center O1-O1 of the camshaft 4 by the amount of eccentricity [epsilon], so that the rotational phase β of the camshaft 4 is shown in FIG. As shown, a relative change is made with respect to the rotational phase α of the crankshaft 1, and a phase difference Φ is generated between these rotational phases α and β by the following equation (1).

Numeral 8 denotes a disk holder for accommodating the eccentric disk 9 rotatably. As shown in FIG. 13, the disk holder 8 is annularly mounted at one end side to the engine body side via a fixing pin 8A so as to be swingable. Part 8B and the annular part 8B
And a pair of engagement claws 8C, 8C integrally formed on the other end of the pair.

Reference numeral 9 denotes the drive shaft 2 connected to the camshaft 4
And an eccentric disk 9 connected to the eccentric disk 9 as shown in FIG.
And an engaging pin 9B protruding from the other side surface. The engaging pins 9A and 9B are located radially opposite each other across the center O2-O2 of the eccentric disk 9 as shown in FIG. It is arranged in.

The eccentric disk 9 is mounted on the disk holder 8
Are accommodated in the annular portion 8B so as to be rotatable around the center O2 -O2, and the engaging pins 9A and 9B are slidably engaged in the engaging grooves 5A and 6A of the connecting plates 5 and 6. ing. Thereby, the drive shaft 2 and the camshaft 4
Is connected to each other via the connecting plates 5 and 6 and the eccentric disk 9, and in this state, the eccentric disk 9 is relatively displaceable between the connecting plates 5 and 6 in the radial direction of the camshaft 4 (drive shaft 2). Has become.

Reference numeral 10 denotes a control shaft for eccentrically moving the eccentric disk 9.
Is rotatably provided on the engine body side, and its cam 10
A is slidably disposed between the engaging claws 8C of the disk holder 8. Then, the control shaft 10 is rotated by an actuator or the like, and swings the disk holder 8 together with the eccentric disk 9 via the cam 10A around the fixing pin 8A as shown by a two-dot chain line in FIG.

Accordingly, the eccentric mechanism 7 gives the eccentric amount ε according to the rotation angle τ of the control shaft 10 to the eccentric disk 9, and gives the phase difference Φ according to the eccentric amount ε to the rotation of the crankshaft 1. It occurs between the phase α and the rotation phase β of the camshaft 4.

Here, assuming that the rotation angle τ of the control shaft 10 is 0 ° when the eccentricity ε becomes zero, the rotation angle τ is positive when the control shaft 10 is rotated in the direction of arrow B in FIG. When the control shaft 10 is rotated in the direction opposite to the direction indicated by the arrow B, the rotation angle becomes a negative (minimum side).

Reference numeral 11 denotes a crank angle sensor which constitutes a phase difference detecting means together with the cam position sensor 12. The crank angle sensor 11 is used when the rotation phase α of the crankshaft 1 becomes a predetermined rotation phase as shown in FIG. The reference signal S1 is output as a detection signal as shown in FIG.

Reference numeral 12 denotes a cam position sensor provided on the camshaft 4 side. As shown in FIG. 14, the cam position sensor 12 has a rotation phase β of the camshaft 4 of, for example, 90 ° or 27 °.
When a predetermined rotation phase such as 0 ° is detected, this is detected, and a reference signal S2 is output as shown in FIG.

Here, the crank angle sensor 11 and the cam position sensor 12 determine that the camshaft 4 makes one rotation (360 °).
During this operation, the reference signals S1 and S2 are each output twice. When a phase difference .PHI. Occurs between the crankshaft 1 and the camshaft 4 due to the eccentric mechanism 7, the reference signal S2 of the cam position sensor 12 becomes, for example, as shown in FIG. Since the relative displacement from the position synchronized with the reference signal S1 is made by the phase difference Φ, the phase difference Φ is calculated based on the time T1 between these reference signals S1 and S3 and the engine speed N.

[0021]

## EQU1 ## Detection is performed as Φ = k × T1 × N (where 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 control means. The control unit measures the time T1 between the reference signals S1 and S3 to detect the phase difference Φ based on the equation 1, and calculates the rotation angle τ of the control shaft 10 based on the detected value. And by operating the actuator, the rotation angle τ of the control shaft 10 is increased.
Feedback control.

The prior art valve timing control device for an engine has the above-described configuration, and its operation will be described below.

First, the crankshaft 1 is driven by the engine.
Is rotationally transmitted to the drive shaft 2 via the timing belt 3, and the connecting plate 5 and the eccentric disk 9 are moved in the disk holder 8 as shown in FIG.
The rotational driving force is transmitted to the camshaft 4 via the engaging pin 9B of the eccentric disk 9 and the connecting plate 6, and the rotational phase β of the camshaft 4 is set to a predetermined value. Each of the intake valves is opened and closed when the rotation phase is reached.

When the control shaft 10 is rotated by the actuator to change the opening / closing timing of the intake valve, the eccentric disk 9 moves relative to the connecting plates 5 and 6 in the radial direction of the camshaft 4 as shown in FIG. The camshaft 4 is displaced, and its center O2-O2 is eccentric from the center O1-O1 of the camshaft 4 by the amount of eccentricity ε.

As a result, the rotational phase β of the camshaft 4
Is the phase difference Φ with respect to the rotational phase α of the crankshaft 1.
The opening / closing timing of the intake valve opened and closed by the camshaft 4 changes in accordance with the phase difference Φ. Therefore, by changing the phase difference Φ to a desired value, the opening / closing timing of the intake valve is appropriately controlled. can do.

That is, in a state where the eccentric disk 9 is eccentric by an eccentric amount ε1 (ε1> ε) as illustrated in FIG.
When the crankshaft 1 (drive shaft 2) has the rotation phase α, the eccentric disk 9 rotates by an angle γ around the center O2. At this time, the camshaft 4 is moved to the center by the engaging pin 9B of the eccentric disk 9. It is rotated around O1, and its rotation phase β has a different value from the rotation phase α.

Then, the rotational phase α of the crankshaft 1
And a rotation phase β of the camshaft 4, there is a phase difference Φ defined by the following equation.

[0029]

## EQU2 ## Φ = α-β

Further, as shown in FIG. 16, the characteristic line of the phase difference Φ has a substantially sinusoidal waveform having a cycle of one rotation (360 °) of the camshaft 4, and changes periodically according to the rotation phase β. I do. Further, since the waveform of the phase difference Φ changes like the characteristic lines 13 and 14 according to the eccentric amounts ε and ε1 of the eccentric disk 9 (rotation angle τ of the control shaft 10),
The rotation angle τ at which the control shaft 10 has actually been rotated can be determined based on the phase difference Φ.

Further, as shown by characteristic lines 13 and 14 in FIG. 16, if the rotational position of the camshaft 4 at which the phase difference Φ becomes substantially zero (hereinafter referred to as a zero point position P0) is 180 °, the camshaft It has been confirmed that when the rotation phase of No. 4 is 90 ° and 270 °, the change amount of the phase difference Φ with respect to the rotation angle τ is large. Therefore, the first rotation phase β1 is set to 90 ° as the reference rotation phase of the camshaft 4 from which the phase difference Φ is to be detected, and the second rotation phase β2 is set to 270.
°, and each projection 4B of the camshaft 4 is
It is provided corresponding to the second rotation phases β1, β2.

Then, the first unit is provided in the control unit.
And a characteristic map indicating the relationship between the phase difference Φ and the rotation angle τ at the rotation phase β1 of the second rotation phase β2, and a characteristic map indicating the relationship between the phase difference Φ and the rotation angle τ at the second rotation phase β2. The control unit calculates the rotation angle τ based on the characteristic maps and the detected value of the phase difference Φ.

On the other hand, a method of directly detecting the rotation angle τ of the control shaft 10 by a contact type sensor such as a potentiometer can be considered. However, considering the durability and the like, the reliability of the valve timing control device is reduced. It becomes difficult to maintain.

Therefore, in the prior art, the control unit detects the phase difference Φ based on the reference signals S 1, S 3 from the crank angle sensor 11 and the cam position sensor 12,
The rotation angle τ at which the control shaft 10 is actually rotated is calculated from the detected value by a non-contact method. And
For example, a target value τ0 of the rotation angle τ of the control shaft 10 is calculated based on the engine speed and the like, and the control shaft 10 is feedback-controlled so that the calculated value of the rotation angle τ becomes the target value τ0.

[0035]

In the above-mentioned prior art, each of the projections 4B provided on the camshaft 4 has, for example, a first rotational phase β1 due to a mechanical processing error or the like.
14 may be displaced from the position corresponding to, as indicated by the two-dot chain line in FIG. Further, there is a case where the mounting position of the crank angle sensor 11 or the cam position sensor 12 is misaligned.

In this case, as shown in FIG. 19, an offset corresponding to the displacement is provided between the actual rotation phase β1 ′ of the camshaft 4 for detecting the phase difference Φ and the reference rotation phase β1. An amount .DELTA..beta.1 is generated, and the actual rotational phase .beta.1 'is shifted forward by the offset amount .DELTA..beta.1. For this reason, as shown in FIG.
3 relatively displaces to the position of the reference signal S4 indicated by the two-dot chain line.

As a result, the reference signal S1 is compared with the time T1 between the reference signal S1 output from the crank angle sensor 11 and the reference signal S3 output from the cam position sensor 12.
Since the time T2 between 1 and S4 becomes shorter by the time .DELTA.T corresponding to the offset .DELTA..beta., The phase difference .PHI. The value is smaller than the phase difference Φ when there is no phase difference.

That is, if there is a shift in the detection timing of the rotational phase by the cam position sensor 12 or the like, the actual rotational phase β1 ′ for detecting the phase difference Φ is offset as shown by the characteristic line 15 in FIG. The first rotational phase β by the amount Δβ
Therefore, the phase difference Φ1 ′ detected in the actual rotation phase β1 ′ is smaller than the phase difference Φ1 to be detected in the rotation phase β1 by a phase deviation ΔΦ1. When the rotation angle τ of the control shaft 10 is obtained based on the detected value, there is a problem that a value different from the actual rotation angle τ is calculated.

In some cases, the detected phase difference Φ is shifted from the characteristic line 15 in the direction of the vertical axis in FIG.
Therefore, the correction can be made in a software manner since it is constant irrespective of. On the other hand, the rotation phase β1 ′ which is the actual detection timing when detecting the phase difference Φ is the first rotation phase β1
, The phase deviation ΔΦ1 changes according to the rotation angle τ of the control shaft 10, and therefore cannot be corrected by the same processing as the correction of the deviation in the vertical axis direction.

Therefore, in the prior art, the actual rotation angle τ
Therefore, there is a problem that it is difficult to accurately perform feedback control of the control shaft 10 so that the target value becomes the target value τ0, and 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, and the present invention provides a method of detecting a phase difference even when a rotational phase, which is a detection timing for detecting a phase difference by a phase difference detecting means, is shifted. It is an object of the present invention to provide a valve timing control device for an engine in which an operation amount of a variable means can be obtained by a correction operation, and feedback control can be performed while stabilizing the rotation phase variable means.

[0042]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a crankshaft, a camshaft which is driven by the crankshaft to open and close an intake or exhaust valve, and an opening and closing of the valve. Rotation phase varying means for causing a phase difference in the rotation phase of the crankshaft and the camshaft by changing the rotation phase of the camshaft to change the timing,
Phase difference detecting means for detecting a phase difference generated between the crankshaft and the camshaft at a predetermined rotation phase by the rotation phase varying means, and at least a phase difference detection result obtained by the phase difference detecting means. And a control means for feedback-controlling the rotational phase variable means.

The first aspect of the present invention is characterized in that the phase difference detected by the phase difference detecting means is read as a first detection value in a state where the rotation phase variable means is set to the minimum operation amount. A first reading unit, a second reading unit that reads a phase difference by the phase difference detecting unit as a second detection value in a state where the rotation phase variable unit is set to a maximum operation amount, and the first reading unit; Phase difference correction means for performing a phase difference correction calculation by the phase difference detection means based on a first detection value by the reading means and a second detection value by the second reading means; and An operation amount calculation unit that calculates an operation amount of the rotation phase variable unit based on a phase difference by the phase difference correction unit; and an operation amount calculated by the operation amount calculation unit is a value corresponding to a target value. The rotation phase variable means is controlled. Lies in the configuration of a signal output means for outputting a signal.

According to the above configuration, the phase difference detected by the phase difference detecting means is read as the first detection value by the first reading means while the rotation phase variable means is set to the minimum operation amount, and the rotation phase variable means is controlled. Since the phase difference detected by the phase difference detecting means is read as the second detection value by the second reading means in a state where the means is set to the maximum work amount, the phase difference correcting means detects the phase difference by the phase difference detecting means. Even when the timing (rotational phase) is deviated, the deviation can be corrected based on the first and second detection values, and the detected value of the phase difference can be used as the operation amount of the rotation phase variable means. Can be made to correspond. The actuation amount calculating means calculates the actuation amount of the rotation phase variable means based on the phase difference by the phase difference correcting means, and the signal output means makes the actuation amount calculation value by the actuation amount calculation means a value corresponding to the target value. Thus, a control signal can be output to the rotation phase variable means so that the feedback control can be performed while the rotation phase variable means is stabilized.

Further, in the invention according to the second aspect, there is provided a characteristic storage means for storing the characteristic of the phase difference with respect to the operation amount of the rotation phase variable means for each different rotation phase, and the phase difference correction means comprises: Phase difference width calculating means for calculating a phase difference width obtained by summing the first detection value and the second detection value; and calculating an offset amount of the phase difference detection means from the phase difference width by the phase difference width calculation means. Offset amount calculating means for calculating, actual rotational phase calculating means for calculating an actual rotational phase for which a phase difference is detected by the phase difference detecting means from the offset amount obtained by the offset amount calculating means, and the actual rotational phase And characteristic selecting means for selecting one of the characteristics of the phase difference stored in the characteristic storing means based on the actual rotational phase by the calculating means.

According to the above configuration, the first phase difference width calculating means is used for the first
And the second detection value can be calculated to calculate the phase difference width. The offset amount calculation means serves as a reference and a detection timing (rotation phase) when the phase difference detection means actually detects the phase difference. An offset amount that is a difference from the detection timing (rotational phase) can be obtained by calculation based on the phase difference width. Then, the actual rotational phase calculating means calculates the actual rotational phase from the offset amount by the offset amount calculating means, so that the characteristic selecting means corresponds to the actual rotational phase from among the characteristics of the phase difference stored in the characteristic storing means. One characteristic can be selected.

Further, in the invention described in claim 3, the actual rotation phase calculating means determines whether or not the actual rotation phase is larger than a reference rotation phase. The actual rotation phase is calculated by adding the offset amount to the rotation phase, and when it is determined to be small, the actual rotation phase is calculated by subtracting the offset amount from the reference rotation phase.

With the above configuration, when the actual rotation phase is larger than the reference rotation phase, the offset amount can be added to the reference rotation phase to calculate the actual rotation phase. The actual rotational phase can be calculated by subtracting the offset amount.

[0049]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 to 11 show an embodiment of the present invention. In this embodiment, the same components as those of the prior art are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 21 denotes a control unit constituted by a microcomputer or the like. The control unit 21 has a storage unit 21A composed of a ROM, a RAM, and the like. What constitutes. The input side of the control unit 21 is connected to the crank angle sensor 11 and the cam position sensor 12, and the output side is connected to an actuator 22 described later.

Here, the storage unit 21A of the control unit 21 stores a program for valve timing control processing (see FIG. 2) and a program for phase difference correction processing (see FIGS. 3 to 5), which will be described later. ing. The storage unit 21A stores a target value τ0 of the rotation angle τ for rotating the control shaft 10 according to the operation state of the engine as a characteristic map corresponding to, for example, the engine speed and the basic injection amount. Have been.

Further, a characteristic map such as a characteristic line 24 indicated by a dotted line in FIG. 7 is stored in the storage unit 21A. In this characteristic map, the rotation angle of the control shaft 10 is set to the minimum value (−τ) with the eccentric mechanism 7 as the minimum operation amount.
m), which is obtained as a phase difference between the crankshaft 1 and the camshaft 4 with respect to the rotation phase β of the camshaft 4 when m).

The phase difference Φ in this case is represented by the characteristic line 24
As shown in the figure, the rotation phase β changes substantially sinusoidally with respect to the rotation phase β of the camshaft 4, but is not strictly a sine wave, and the minimum value (negative value) of the characteristic line 24 is smaller than 90 °. Is small, for example, about 80 °, and the maximum value (positive value) is a rotational phase β larger than 270 °, for example, about 280 °.

Further, a characteristic map such as a characteristic line 25 indicated by a solid line in FIG. 7 is stored in the storage unit 21A. This characteristic map shows the phase difference between the crankshaft 1 and the camshaft 4 with respect to the rotation phase β of the camshaft 4 when the rotation angle of the control shaft 10 is set to the maximum value τm with the eccentric mechanism 7 as the maximum operation amount. It is obtained.

The phase difference Φ in this case is represented by the characteristic line 25
As shown in the figure, the rotation phase β changes substantially sinusoidally with respect to the rotation phase β of the camshaft 4, but is not strictly a sine wave, and the maximum value (positive value) of the characteristic line 24 is greater than 90 °. Is smaller, for example, about 100 °, and the minimum value (negative value) is smaller than 270 °.
It has been confirmed that the rotation phase becomes about °.

The storage unit 21A stores a characteristic map (see FIGS. 8 and 10) of the phase difference width with respect to the detection timing (rotation phase) when the phase difference is actually detected. It is stored as follows. Here, these characteristic maps are experimentally obtained based on the characteristic lines 24 and 25 in FIG.

Further, the storage unit 21A stores the crankshaft 1 with respect to the rotation angle τ of the control shaft 10,
The characteristic map of the phase difference between the camshafts 4 (see FIGS. 9 and 11) shows characteristic lines 27 to 29 and characteristic lines 31 to 31 described later as characteristics for each different rotation phase of the camshaft 4.
3, and the storage section 21A constitutes a characteristic storage means.

Reference numeral 22 denotes an actuator for rotating the control shaft 10.
As disclosed in Japanese Patent Application No. 7-196256 by the present applicant, a spool valve device driven and controlled by a proportional solenoid, a linear stepping motor, or the like, and a pressure valve via the spool valve device. A hydraulic cylinder (both not shown) that expands and contracts the rod when oil is supplied and discharged, and rotates the control shaft 10 in response to a drive signal output from the control unit 21 in substantially the same manner as in the related art. To move.

The valve timing control apparatus for an engine according to the present embodiment has the above-described configuration. Next, valve timing control processing and phase difference correction processing by the control unit 21 will be described with reference to FIGS. .

First, when the control unit 21 determines that the engine is in an operation state in which valve timing control should be performed based on the engine speed and the like, the control unit 21 starts a valve timing control process shown in FIG. Then, in step 1, the phase difference correction processing program (described later) in the characteristic map of the phase difference at the first and second rotation phases β1 and β2 (see FIGS. 9 and 11) stored in the storage unit 21A. The characteristic map of the phase difference selected in
Read from A.

Here, the first and second rotation phases β1, β2
Indicates a reference rotation phase, and the rotation phase is determined with respect to the zero point position P0 of the camshaft 4 where the phase difference Φ becomes substantially zero as shown by the characteristic line 23 in FIG. Is determined in advance as a rotation phase whose phase is shifted by a certain angle (for example, 90 °) to the front and rear sides of the rotation direction. If the zero point position P0 is 180 °, the first rotational phase β1 is set at 90 °, and the second rotational phase β2 is 270 °.
And the projections 4B of the camshaft 4 are provided corresponding to the first and second rotation phases β1, β2.

In the case of this embodiment, as shown in FIG. 6, the detection timing of the phase difference by the cam position sensor 12 or the like is actually changed from the first and second rotation phases β1, β2 to the rotation phase β1a. , Β2a, the following steps 2 and later will be described. In this case, the first rotation phase β
It is assumed that the characteristic line 29 is selected from the characteristic map shown in FIG. 9 on the 1 side, and the characteristic line 33 is selected from the characteristic map shown in FIG. 11 on the second rotational phase β2 side.

Next, at step 2, the projection 1 B of the crankshaft 1 is detected by the crank angle sensor 11, and each projection 4 B of the camshaft 4 is detected by the cam position sensor 12. Then, as shown in FIG. 6, the control unit 21 moves the projection 4 of the camshaft 4 at the position of the rotation phase β1a.
When B is detected, the phase difference .PHI. At this time is read as a detected value .PHI.1 ', and when the projection 4B of the camshaft 4 is detected at the position of the next rotational phase .beta.2a, the phase difference .PHI. At this time is set as a detected value .PHI.2'. Read.

In step 3, the rotation angle τ of the control shaft 10 is calculated from the detected value Φ1 'in step 2 based on the phase difference characteristic map shown in FIG.
Based on the phase difference characteristic map shown in FIG. 1, the rotation angle .tau.
Is calculated. Thus, the rotation angle τ of the control shaft 10 actually rotated by the actuator 22 is obtained.

Next, in step 4, in order to perform feedback control of the control shaft 10, a target for the rotation angle τ of the control shaft 10 is obtained from a characteristic map in the storage unit 21A based on, for example, the engine speed and the basic injection amount. A value τ0 is calculated, and a control amount of the actuator 22 required to make a difference between the target value τ0 and the rotation angle τ of the control shaft 10 obtained in step 4 equal to or smaller than a predetermined hysteresis value is calculated.

In step 5, a drive signal corresponding to the control amount calculated in step 4 is applied to the actuator 22.
Output to Then, the control shaft 10 is rotated by the actuator 22 so that the rotation angle τ substantially becomes the target value τ0.

Thus, the rotational phase β of the camshaft 4
Is the rotation angle τ of the control shaft 10 (the target value τ0
) Changes with respect to the rotation phase α of the crankshaft 1 by the phase difference Φ, and the camshaft 4 opens and closes each intake valve at an appropriate timing corresponding to the engine speed and the like.

Next, at step 6, it is determined whether or not the valve timing control is in an operation state to continue the valve timing control as described above, based on, for example, the engine speed. By repeating the above processing, feedback control is performed such that the rotation angle τ of the control shaft 10 always becomes a value corresponding to the target value τ0.

When the determination in step 6 is "NO", it means that the condition for stopping the valve timing control is satisfied, for example, when the engine speed becomes high, and so the process proceeds to step 7. Return to end the valve timing control.

Next, the actual detection timing (for example, the rotation phases β1a and β2a) for detecting the phase difference is obtained, and the phase difference correction processing for selecting the phase difference characteristic map corresponding thereto is shown in FIGS. This will be described with reference to FIG.

First, in step 11 shown in FIG. 3, the operating state of the engine is detected, and it is determined whether or not the condition for performing the phase difference correction processing is satisfied. In this case, the above condition is satisfied when the engine is rotating at a constant rotational speed, for example, when the engine is idling (no load) or when the vehicle is traveling at a constant speed.

Then, if "NO" is determined in the step 11, the engine speed is unstable and the process proceeds to the step 20 and returns. In this case, the storage unit 21A
In the characteristic map of the phase difference stored in FIG.
A characteristic map of the phase difference used in the prior art as shown by the characteristic line 29 in the middle and the characteristic line 33 in FIG. 11 is selected.

On the other hand, if "YES" is determined in step 11, the condition is satisfied, and the process proceeds to step 12 to drive the actuator 22 so that the eccentric mechanism 7 is set to the minimum operation amount and the control shaft 10
Is temporarily fixed to a minimum value (−τm), for example, −45 °.

In step 13, the phase difference Φ with the rotation angle of the control shaft 10 set to the minimum value (−τm) is detected on the first rotation phase β1 side, and the actual detection timing is set to the rotation phase. When it is at the position of β1a, the phase difference Φ at this time is read as the first detection value a1. Next, at step 14, the control shaft 1
The phase difference Φ when the rotation angle of 0 is the minimum value (−τm)
Is detected on the side of the second rotation phase β2, and when the actual detection timing is at the position of the rotation phase β2a, the phase difference Φ at this time is read as the first detection value a2.

Next, in step 15, by driving the actuator 22, the eccentric mechanism 7 is set to the maximum operation amount, and the rotation angle of the control shaft 10 is temporarily set to the maximum value τm, for example, 45 °. Fix it.

In step 16, the phase difference Φ with the rotation angle of the control shaft 10 at the maximum value τm is detected on the first rotation phase β1 side, and the actual detection timing is the position of the rotation phase β1a. Is read as the second detected value b1. Next, in step 17, the phase difference Φ with the rotation angle of the control shaft 10 at the maximum value τm is detected on the second rotation phase β2 side, and the actual detection timing is the position of the rotation phase β2a. , The phase difference Φ at this time is
Is read as the detected value b2.

Then, in step 18, the first rotational phase β1 is set as in steps 31 to 39 shown in FIG.
In step 19, a characteristic selection process for selecting a characteristic map of the phase difference is performed, and in step 19, a later-described step 41 shown in FIG.
As in the case of .about.49, a characteristic selection process for selecting a characteristic map of the phase difference at the second rotational phase .beta.2 is performed, and the process proceeds to step 20 and returns.

Next, a characteristic selection process for selecting a characteristic map of the phase difference at the first rotation phase β1 will be described in detail with reference to FIG.

First, at step 31 in FIG. 4, the phase difference width L1 obtained by summing the detection value a1 and the detection value b1 is calculated as
It is calculated as the difference between the detected value a1 and the detected value b1 (L1 = b1 -a1). Here, the phase difference width L1 is obtained by changing the rotation angle of the control shaft 10 from the minimum value (−τm) to the maximum value τ.
This is the width of the change in the phase difference Φ detected at the position of the rotation phase β1a when changed to m.

Next, in step 32, the characteristic map shown in FIG. 8 is read from the storage unit 21A of the control unit 21, the rotation phase β1a or β1b corresponding to the phase difference width L1 is calculated, and the first rotation phase By taking the difference between β1 and the rotation phases β1a, β1b, the offset amount Δ
Calculate β1.

That is, the characteristic line 26 in FIG. 8 is obtained by summing the values of the phase difference Φ by the characteristic lines 24 and 25 in FIG. 7, and the phase difference width L and the rotation phase β at this time are obtained. The relationship is shown. The phase difference width L is equal to the rotation phase β.
Is 90 °, which is the first rotation phase β1, and the phase difference width L decreases when the rotation phase β departs from 90 °. According to the characteristic line 26, the phase difference width L has two values before and after the position where the rotation phase β is 90 °, and at this time, the rotation phase β1a has an offset Δβ1 smaller than 90 °.
And the rotation phase β1b is a value larger than 90 ° by the offset amount Δβ1. Therefore, the actual detection timing is specified from the rotation phases β1a and β1b by performing the following processing.

In step 33, as the estimated rotation phase of the rotation phase at which the detected values a1, b1 are detected, the rotation phase β smaller than the first rotation phase β1 by the offset amount Δβ1
1a (β1a = β1−Δβ1) and a rotation phase β1b (β1b = β1b) that is larger than the first rotation phase β1 by an offset amount Δβ1.
β1 + Δβ1).

Next, at step 34, the characteristic map indicated by the characteristic line 24 in FIG. 7 is read from the storage unit 21A of the control unit 21, and the rotation angle τ of the control shaft 10 is set to the minimum value (−τm). In addition to calculating the phase difference to be detected at the position of the rotational phase β1b as the estimated value a1 ', the characteristic map indicated by the characteristic line 25 in FIG. 7 is read from the storage unit 21A, and the rotational angle τ of the control shaft 10 is determined. A phase difference to be detected at the position of the rotation phase β1b when the maximum value τm is set is calculated as an estimated value b1 '.

In step 35, the calculated value x1 which is the difference between the absolute value of the detected value a1 and the absolute value of the estimated value a1 'is obtained.
(X1 = | a1 |-| a1 '|) and an operation value y1 (y1 = | b1 |-| b1' |) which is a difference between the absolute value of the detected value b1 and the absolute value of the estimated value b1 '. ) Is calculated.

Next, at step 36, these calculated values x
1 and the difference between the absolute values of the operation value y1 (| x1 -y1 |)
Is determined to be less than or equal to a small hysteresis value δ,
If "NO" is determined, the detected value a1 and the estimated value a1
Are different from the detected value b1 and the estimated value b1 ', the detection timing of the detected values a1 and b1 is determined to be the rotation phase .beta.1a.

In step 37, the characteristic line 27 is selected as the phase difference characteristic map corresponding to the rotation phase β1a from the phase difference characteristic map in FIG. 9, and the process proceeds to step 39 and returns.

If "YES" is determined in the step 36, the detected value a1 is substantially equal to the estimated value a1 'and the detected value b1 is substantially equal to the estimated value b1'. , B1 is detected at the rotation phase β1b
Then, the routine proceeds to step 38, where the characteristic line 28 is selected as the phase difference characteristic map corresponding to the rotation phase β1b from the phase difference characteristic map in FIG. When the offset amount Δβ1 becomes substantially zero, the characteristic line 29 is selected as a characteristic map of the phase difference, and the routine proceeds to step 39 and returns.

Next, a characteristic selection process for selecting a characteristic map of the phase difference at the second rotational phase β2 will be described in detail with reference to FIG.

First, in step 41 in FIG. 5, the phase difference width L2 obtained by summing the detected value a2 and the detected value b2 is calculated as
It is calculated as the difference between the detected value a2 and the detected value b2 (L2 = a2-b2). Here, the phase difference width L2 is obtained by changing the rotation angle of the control shaft 10 from the minimum value (−τm) to the maximum value τ.
This is the width of change that occurs in the phase difference Φ detected at the position of the rotation phase β2a when changed to m.

Next, at step 42, the characteristic map shown in FIG. 10 is read from the storage unit 21A of the control unit 21, the rotation phase β2a or β2b corresponding to the phase difference width L2 is calculated, and the second rotation phase The offset amount Δβ2 is calculated by taking the difference between β2 and the rotation phases β2a and β2b.

That is, the characteristic line 30 in FIG. 10 is obtained by summing the values of the phase difference Φ by the characteristic lines 24 and 25 in FIG. 7, and the phase difference width L and the rotation phase β at this time are obtained.
The relationship is shown. The phase difference width L has a maximum value when the rotation phase β is 270 °, which is the second rotation phase β2, and when the rotation phase β departs from 270 °, the phase difference width L becomes larger.
Decreases. According to the characteristic line 30, the phase difference width L has two values before and after the position where the rotational phase β is 270 °, and at this time, the rotational phase β2a is a value smaller than 270 ° by the offset amount Δβ2. And the rotation phase β2b is 270
The value is larger than the angle by the offset amount Δβ2. For this reason, the actual detection timing is specified from the rotation phases β2a and β2b by performing the following processing.

In step 43, as the estimated rotational phase of the rotational phase at which the detected values a2 and b2 are detected, the rotational phase β smaller than the second rotational phase β2 by the offset amount Δβ2
2a (β2a = β2−Δβ2) and a rotation phase β2b (β2b = β2b) that is larger than the second rotation phase β2 by an offset amount Δβ2.
β2 + Δβ2).

Next, at step 44, when the characteristic map indicated by the characteristic line 24 in FIG. 7 is read from the storage unit 21A of the control unit 21, the rotation angle τ of the control shaft 10 is set to the minimum value (−τm). The phase difference to be detected at the position of the rotation phase β2b is calculated as the estimated value a2 ', and the characteristic map indicated by the characteristic line 25 in FIG. 7 is read from the storage unit 21A, and the rotation angle τ of the control shaft 10 is calculated. The phase difference to be detected at the position of the rotation phase β2b when the maximum value τm is set is calculated as an estimated value b2 '.
Then, in step 45, the calculated value x2 (x2 = |
a2 │-│a2 '│) and the calculated value y2 which is the difference between the absolute value of the detected value b2 and the absolute value of the estimated value b2'.
(Y2 = | b2 |-| b2 '|) is calculated.

Next, at step 46, these calculated values x
2 and the difference between the absolute values of the operation value y2 (| x2-y2 |)
Is determined to be less than or equal to a small hysteresis value δ,
When the determination is "NO", the detected value a2 and the estimated value a2
Are different from the detected value b2 and the estimated value b2 ', the detection timing of the detected values a2 and b2 is determined to be the rotation phase β2a, and the routine proceeds to step 47.

In step 47, the characteristic line 31 is selected as the phase difference characteristic map corresponding to the rotation phase β2a from the phase difference characteristic map in FIG.
Move to and return.

If "YES" is determined in step 46, the detected value a2 is substantially equal to the estimated value a2 'and the detected value b2 is substantially equal to the estimated value b2'. , B2 is detected at the rotation phase β2b
Then, the process proceeds to a step 48, wherein the characteristic line 32 is selected as a phase difference characteristic map corresponding to the rotation phase β2b from the phase difference characteristic map in FIG. When the offset amount Δβ2 becomes substantially zero, the characteristic line 33 is selected as a characteristic map of the phase difference, and the routine proceeds to step 49 and returns.

The valve timing control apparatus according to the present embodiment is configured as described above. When this valve timing control apparatus is operated, an accurate rotation angle τ of the control shaft 10 is detected as follows. it can.

For example, a position shift due to a manufacturing error or the like occurs in each projection 4B of the camshaft 4, and as shown in FIG. 6, the actual rotation phase β1a for detecting the phase difference is changed
When the offset value Δβ1 is smaller than 1, the detected value Φ1 ′ detected in the actual rotation phase β1a becomes the first value.
Is smaller than the phase difference Φ1 to be detected in the rotation phase β1.

At this time, in the valve timing control device according to the prior art, the detected value .phi.1 'is controlled by using the phase difference characteristic map shown by the characteristic line 28 in FIG. 9 assuming that the detected value .phi.1' is detected in the first rotational phase .beta.1. Shaft 10
Is calculated, a rotation angle τ1 ′ smaller than the actual rotation angle τ1 is calculated.

On the other hand, in the valve timing control device according to the present embodiment, the phase difference characteristic map shown by the characteristic line 29 is selected from the phase difference characteristic map in FIG. 9 by performing the phase difference correction processing. .

In the valve timing control process, the characteristic map of the phase difference selected by the phase difference correction process is read out from the storage unit 21A of the control unit 21, and the position difference is compared with the detected value Φ1 'detected at the position of the rotational phase β1a. Control shaft 1 based on phase difference characteristic map
An accurate rotation angle τ1 of 0 can be calculated.

The actual rotation phase β for detecting the phase difference
When 2a is smaller than the second rotation phase β2 by the offset amount Δβ2, the detection value Φ2 ′ detected at the position of the rotation phase β1a is smaller than the phase difference Φ2 to be detected in the second rotation phase β2. Value. At this time, since the valve timing control device according to the prior art uses the characteristic map of the phase difference indicated by the characteristic line 32 in FIG. 11, the rotation angle smaller than the actual rotation angle τ2 of the control shaft 10 based on the detected value A2. The moving angle τ2 'is calculated.

However, the valve timing control apparatus according to the present embodiment performs the phase difference correction processing to perform
1, a characteristic map of the phase difference indicated by the characteristic line 33 is selected from the characteristic map of the phase difference, and based on the detected value Φ2 ′ detected at the position of the rotational phase β2a based on the selected characteristic map of the phase difference. Since the rotation angle τ of the control shaft 10 is calculated, the actual rotation angle τ2 can be calculated accurately.

As described above, the detection timing of the phase difference Φ is
The rotation phase β1a, smaller than the second rotation phase β1, β2,
Although the description has been given of the case where the position is shifted to β2a, the same processing is performed when the detection timing of the phase difference Φ is shifted to a rotation phase larger than the first and second rotation phases β1 and β2. Correction calculation can be performed, and an accurate rotation angle of the control shaft 10 can be detected.

Thus, in this embodiment, the phase difference when the control shaft 10 is set to the minimum rotation angle (-τm) is read as the first detection values a1 and a2, and the control shaft 10 is set to the maximum rotation angle. The phase difference when τm is set is read as the second detection values b1 and b2, and the phase difference correction calculation is performed based on the first detection values a1 and a2 and the second detection values b1 and b2. Even when the projections 4B and the like of the camshaft 4 are displaced and the detection timing (rotation phase) for detecting the phase difference by the cam position sensor 12 and the like is deviated, the rotation angle τ of the control shaft 10 is accurately calculated. Can be sought.

Since the accurate rotation angle τ of the control shaft 10 can be calculated, the control unit 2
1 performs stable feedback control so that the rotation angle τ becomes a value corresponding to the target value τ0. In addition, the valve timing of the engine can be controlled with high responsiveness, and the engine can be driven in an optimal state corresponding to the operating state of the engine. Can be improved.

Further, a phase difference width L1 (L2) obtained by summing the first detection value a1 (a2) and the second detection value b1 (b2).
Is calculated, and the offset amount Δβ1 (Δβ2) is changed to the phase difference width L.
1 (L2) and by calculating the actual rotational phases β1a and β2a from the offset amount Δβ1 (Δβ2), the actual rotational phase β1a ( One characteristic map corresponding to β2a) can be selected.

Further, when the actual rotation phase β1a (β2a) is larger than the reference rotation phase β1 (β2), the offset amount Δβ1 (Δβ1) is added to the reference rotation phase β1 (β2).
2) can be added to calculate the actual rotational phase β1a (β2a). Conversely, if the actual rotational phase β1a (β2a) is smaller, the offset amount Δβ1 (Δβ2) is subtracted from the reference rotational phase β1 (β2). Can be calculated.

In the above embodiment, in the program shown in FIGS. 2 to 5, step 3 shows a specific example of the operation amount calculating means which is a component of the present invention.
Shows a specific example of the signal output means. Steps 12 to 14 show specific examples of the first reading means, steps 15 to 17 show specific examples of the second reading means, and steps 18 and 19 show specific examples of the phase difference correcting means. Steps 31 and 41 show a specific example of the phase difference width calculating means. Further, steps 32 and 42 show specific examples of the offset amount calculating means, steps 33 to 36 and steps 43 to 46 show specific examples of the actual rotation phase calculating means, and steps 37, 38, 47 and 48 show the characteristics. Specific examples of the selection means are shown.

In the above embodiment, the rotational phase β and the phase difference Φ of the camshaft 4 temporally calculated based on the reference signals S 1 and S 3 of the crank angle sensor 11 and the cam position sensor 12 are based on the engine speed. Although the present invention is not limited to this, the present invention is not limited to this. For example, an angle signal is output from the crank angle sensor 11 or the like to the control unit 21, for example, every 1 °, and the rotation phase β is determined based on the angle signal. Or the phase difference Φ may be directly detected as an angle.

Further, in the above-described embodiment, the valve timing control device for controlling the opening / closing timing of the intake valve has been exemplified as the prior art. However, the present invention is not limited to this, and one of the intake valve and the exhaust valve is not limited thereto. The present invention may be applied to a valve timing control device that controls opening / closing timing, or may be applied to a valve timing control device that controls opening / closing timing of both an intake valve and an exhaust valve.

[0113]

As described above in detail, according to the first aspect of the present invention, the first reading for reading the phase difference in the state where the rotation phase variable means is set to the minimum operation amount as the first detection value. Means, a phase difference when the eccentric mechanism 7 is set to the maximum operation amount, as a second detection value, a second reading means, and a phase difference correction calculation based on the first and second detection values. And a phase difference correction means for performing the phase difference correction, the difference is corrected based on the first and second detection values even if there is a shift in the phase difference detection timing (rotation phase) by the phase difference detection means. Calculation can be performed, the detected value of the phase difference can be made to correspond to the operation amount of the rotation phase variable means, and the operation amount of the rotation phase variable means can be accurately calculated.

Then, by calculating the operation amount of the rotation phase variable means based on the phase difference by the phase difference correction means, the signal output means makes the calculated value of the operation amount by the operation amount calculation means equal to the value corresponding to the target value. As a result, the control signal can be output to the rotation phase variable means, and the feedback control can be performed while stabilizing the rotation phase variable means. In addition, the valve timing of the engine can be controlled stably, and the engine can be driven in an optimal state corresponding to the operating state of the engine. In addition, appropriate intake and exhaust are performed, and the operating performance of the engine is improved. Can be improved.

According to the second aspect of the present invention, the phase difference correcting means is constituted by the phase difference width calculating means, the offset amount calculating means, the actual rotation phase calculating means and the characteristic selecting means. And the phase difference width obtained by summing the first and second detection values can be calculated, and the offset amount calculation means can calculate the offset amount based on the first and second detection values by calculation. Then, the actual rotation phase calculation means calculates the actual rotation phase from the offset amount, and selects one characteristic corresponding to the actual rotation phase from the characteristics of the phase difference stored in the characteristic storage means by the characteristic selection means. can do.

According to the third aspect of the present invention, the actual rotation phase calculating means determines whether or not the actual rotation phase is larger than the reference rotation phase. Is larger than the reference rotation phase, the actual rotation phase can be calculated by adding the offset amount to the reference rotation phase. Conversely, when the rotation phase is smaller than the reference rotation phase, the actual rotation phase is calculated by subtracting the offset amount from the reference rotation phase. be able to.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing a control process of valve timing control by a control unit in FIG. 1;

FIG. 3 is a flowchart showing a phase difference correction process in FIG. 2;

FIG. 4 is a flowchart showing a characteristic selection process at a rotation phase β1 in FIG. 3;

FIG. 5 is a flowchart showing a characteristic selection process at a rotation phase β2 in FIG. 3;

FIG. 6 is a characteristic diagram showing a change in a phase difference with respect to a rotation phase of a camshaft.

FIG. 7 is a characteristic diagram showing a change in a phase difference with respect to a rotation phase of a camshaft when a rotation angle of a control shaft is set to a maximum side and to a minimum side.

FIG. 8 is a characteristic diagram showing characteristics of a phase difference width with respect to a first rotation phase.

FIG. 9 is a characteristic diagram illustrating a relationship between a phase difference at a first rotation phase and a rotation angle of a control shaft.

FIG. 10 is a characteristic diagram illustrating characteristics of a phase difference width with respect to a second rotation phase.

FIG. 11 is a characteristic diagram illustrating a relationship between a phase difference at a second rotation phase and a rotation angle of a control shaft.

FIG. 12 is a partially cutaway front view showing a crankshaft, a camshaft, and the like according to the related art.

FIG. 13 is a sectional view showing the eccentric disk together with a control shaft and the like as viewed from the direction indicated by arrows XIII-XIII in FIG. 12;

FIG. 14 is an arrow in FIG. 12 showing a crankshaft, a camshaft, a crank angle sensor, a cam position sensor, and the like.
It is the side view seen from the XIV-XIV direction.

FIG. 15 is an explanatory view showing a state where the eccentric disk in FIG. 13 is eccentric with respect to a camshaft.

16 is a characteristic diagram illustrating a change in a phase difference with respect to a rotation phase of a camshaft according to an eccentric amount of an eccentric disk in FIG. 13;

FIG. 17 is an explanatory view similar to FIG. 15, showing a state in which the eccentric disk is rotated by a drive shaft.

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

19 is a characteristic diagram showing a state in which a phase error has occurred between a phase difference and a normal phase difference when the protrusion of the camshaft in FIG. 14 has shifted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankshaft 4 Camshaft 7 Eccentric mechanism (variable rotation phase difference means) 9 Eccentric disk 10 Control shaft 11 Crank angle sensor 12 Cam position sensor 21 Control unit

Claims (3)

[Claims] 1. A crankshaft, a camshaft rotationally driven by the crankshaft to open and close an intake or exhaust valve, and changing a rotational phase of the camshaft to change the opening / closing timing of the valve. A rotation phase variable means for generating a phase difference in the rotation phase between the crankshaft and the camshaft; and a phase difference generated between the crankshaft and the camshaft by the rotation phase variable means at a predetermined rotation phase. An engine valve timing control device comprising: a phase difference detecting means for detecting; and a control means for performing feedback control of the rotational phase variable means based on at least a detection result of the phase difference by the phase difference detecting means. With the means set to the minimum operation amount, the position of the A first reading means for reading the difference as a first detection value; and a second reading means for reading a phase difference by the phase difference detection means as a second detection value in a state where the rotation phase variable means is set to a maximum operation amount. And a phase difference for performing a phase difference correction calculation by the phase difference detection means based on a first detection value by the first reading means and a second detection value by the second reading means. Correction means, wherein the control means calculates an operation amount of the rotation phase variable means based on the phase difference by the phase difference correction means, and the calculated value of the operation amount by the operation amount calculation means is And a signal output means for outputting a control signal to said variable rotation phase means so as to have a value corresponding to a target value. 2. The apparatus according to claim 1, further comprising: a characteristic storage unit configured to store a characteristic of the phase difference with respect to an operation amount of the rotation phase variable unit for each of different rotation phases. Phase difference width calculating means for calculating a phase difference width obtained by summing the two detected values, an offset amount calculating means for calculating an offset amount of the phase difference detecting means from the phase difference width by the phase difference width calculating means, An actual rotational phase calculating means for calculating an actual rotational phase in which the phase difference is detected by the phase difference detecting means from the offset amount obtained by the offset amount calculating means, and an actual rotational phase calculated by the actual rotational phase calculating means. 2. The engine valve timing control device according to claim 1, further comprising: a characteristic selection unit that selects any one of the characteristics of the phase difference stored in the characteristic storage unit. 3. The actual rotation phase calculating means determines whether or not the actual rotation phase is larger than a reference rotation phase, and when it is determined to be larger, adds the offset amount to the reference rotation phase. 3. The engine valve timing according to claim 2, wherein the actual rotation phase is calculated by calculating the actual rotation phase, and when it is determined to be smaller, the actual rotation phase is calculated by subtracting the offset amount from the reference rotation phase. Control device.