JPH08177535A - Valve timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To improve learning accuracy and controllability so as to obtain excellent exhaust gas emission by constructing a learning control system including steady disturbance such as manufacturing tolerance and change with the lapse of time applied to a control object in a variable valve timing control system. CONSTITUTION: On the basis of the positions of a crankshaft 11 and a camshaft 16 detected by position sensors 17, 18 and steady disturbance modeled to dynamic characteristics, a control device 70 controls the position of a spool valve 53 by the linear solenoid 56 of a hydraulic device 50. As a result, oil is fed to phase adjusting mechanism 20 from an oil pan 51 by an oil pump 52 driven by an engine 10 so as to change the phase of the camshaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic valve timing control system for an internal combustion engine.

[0002]

2. Description of the Related Art By continuously controlling the opening of a hydraulic pressure adjusting solenoid valve for driving intake / exhaust valve timing of an internal combustion engine, and adopting feedback learning control for the opening control of this solenoid valve, In a valve timing control device that can realize advanced angle control with high accuracy, exhaust characteristics are deteriorated because flow characteristics fluctuate due to manufacturing tolerances of the solenoid valve, changes over time, etc., and steady deviations and overshoots occur. It has been known.

In order to prevent this emission deterioration, as described in Japanese Patent Application Laid-Open No. 6-299813, when the electromagnetic valve opening target value is a constant value for a predetermined time or more, that is, a steady state without load fluctuation of the internal combustion engine. At this time, the learning means stores the output value from the control device by the learning means, and the stored output value is used as the learning value.

[0004]

However, the flow rate characteristic of the spool valve, which is the hydraulic pressure adjusting solenoid valve, depends on the operating condition and is mainly determined by the engine speed.
The learning value is a multidimensional map of the engine speed, the oil temperature, etc., since it is greatly affected by the viscosity of the oil and the like determined by the oil temperature, and the learning value data becomes a huge amount.

Therefore, if the learning is carried out only in the steady state of the internal combustion engine as in the prior art, the learning frequency becomes extremely small and the early learning of all the multidimensional maps becomes impossible, so that the exhaust gas emission is greatly affected. give. Further, if the steady state determination range is widened, the learning frequency is improved, but the learning accuracy is deteriorated, and again, the exhaust gas emission is greatly affected.

Therefore, in order to solve the above-mentioned problems, the present invention constructs a dynamic model considering a steady disturbance such as manufacturing tolerance of an electromagnetic valve and a change with time, and a control system which is not affected by the steady disturbance. The purpose is to configure.

[0007]

As shown in FIG. 1, the present invention is provided in a rotation transmission system from a crankshaft to a camshaft of an internal combustion engine in order to solve the above-mentioned problems, and is shown by a hatched portion. A phase adjusting mechanism for changing the rotational phase difference between the two shafts, a drive means for driving the phase adjusting mechanism, various sensors provided in each part of the internal combustion engine and indicating the operating state of the engine, and the sensor Rotational phase difference detection means for calculating an actual phase difference angle between the two axes based on the detected operating state quantity, and a target for determining a target value of the rotational phase difference based on the operating state quantity detected by the sensor. Value determining means, control means for generating a control value for causing the phase difference angle to match a target value of the rotational phase difference and outputting the control value to the driving means, a dynamic characteristic model of the driving means, and the rotational phase difference. Output to the driving means And by a learning means for learning a steady disturbance, the learning value of the learning means is to provide a valve timing control apparatus for an internal combustion engine and a correcting means for correcting the control value.

The dynamic characteristic model may be a model on the assumption that steady disturbance is added to the theoretical value at the center of the driving means for driving the phase adjusting mechanism.

[0009]

The learning control of the present invention having the above-described structure can be executed not only in the steady state but also in the transient state as long as the flow rate characteristic is a linear portion. It is possible to realize feedback control considering For this reason, it is possible to quickly learn manufacturing tolerances, changes with time, etc. immediately after the start of feedback control.
Since the learning does not require a complicated one such as a multidimensional map, there is an effect that the steady disturbance is instantly absorbed and the valve timing control with high accuracy becomes possible.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment to which the present invention is applied will be described with reference to FIGS.
This will be described using 1. FIG. 2 is a configuration diagram of an engine to which the present device is applied. In FIG. 2, 10 is the engine body,
Reference numeral 20 denotes a phase adjustment mechanism (hatched portion) provided in the engine 10, 50 is a hydraulic device for driving the phase adjustment mechanism 20, and 70 is an engine operating state grasped from signals of various sensors provided in the engine 10 and the like, The control part which outputs a control signal to the hydraulic device 50 is shown.

A timing chain 14 is mounted on the crankshaft 11, the exhaust valve sprocket 12, and the intake valve sprocket 13 of the engine 10.
One rotation is transmitted to each cam shaft 15 and 16. In this embodiment, an adjusting mechanism 20 is provided between the sprocket 13 and the cam shaft 16, the sprocket 13 is slid in the direction of the cam shaft rotation axis, and the rotation phase between the sprocket 13 and the cam shaft 16 is changed, so that the intake air is absorbed. The case where the advance angle control of the valve is performed is shown. Of course, the adjusting mechanism 20 is installed on the exhaust valve side,
Alternatively, the same control can be performed by providing both of them.

A crank position detecting sensor 17 is provided near the crank shaft 11, and a cam shaft position detecting sensor 18 is provided near the cam shaft 16. These are electromagnetic pickup type sensors, for example. Each sensor 17, 18
According to the rotation of the shafts 11 and 16 respectively.
A pulsed detection signal is output to. Position detection sensor 17
Generates N signals per revolution of the crankshaft, and the position detection sensor 18 generates 2N signals per revolution of the camshaft. The control unit 70 measures the rotational phase θ between the crankshaft 11 and the camshaft 16 based on these detection signals. still,
When N is the maximum value θ _MAX of the rotation phase angle θ, “N
<360 / θ _MAX ”.

The control unit 70 is combined with an electronic control unit (hereinafter referred to as an ECU) that performs, for example, air-fuel ratio control and idle rotation control, and includes a CPU, RAM, ROM,
It is configured to include an input / output circuit and a current control circuit.
In addition to the above detection signal, the control unit 70 takes in an engine cooling water temperature signal, a throttle opening signal, etc., calculates a control value by a control calculation described in detail later, and outputs the control value to the hydraulic device 50.

Next, FIG. 3 is a sectional view showing a coupling state between the phase adjusting mechanism 20, the sprocket 13, and the cam shaft 16. The adjusting mechanism 20 is configured inside a housing 22 fixed to a cylinder head 21 of the engine 10. A substantially cylindrical camshaft sleeve 23 is fixed by a pin 24 and a bolt 25 to the end of the camshaft 16 extending from the right side of the drawing. The sprocket 13 is engaged with the portion where the sleeve 23 supports the cam shaft 16, and the sprocket 13 is prevented from moving in the rotation axis direction, but can be slid in the rotation direction. There is.

On the other hand, a substantially cylindrical sprocket sleeve 26 is fixed to the sprocket 13 by pins 27 and bolts 28, and an end plate 29 is fixed to the other end of the sleeve 26. Thus the sleeve 23
The cam shaft 16, the sleeve 26, and the sprocket 13 are integrated with each other, and are rotatable within a ring plate 31 fixed to the housing 22 with knock pins 30.

An external tooth helical spline 32a is formed on a part of the outer peripheral side of the camshaft sleeve 23, and an internal tooth helical spline 33a is formed on a part of the inner peripheral side of one sprocket sleeve 26. . A cylinder 34 is fitted between the sleeves 23 and 26, and the helical splines 32a of the sleeves 23 and 26 are
33a meshes with an internal tooth helical spline 32b formed on the inner peripheral side of the cylinder 34, and an external tooth helical spline 33b also formed on the outer peripheral side thereof. As a result, the sleeves 23, 26 and the cylinder 34 rotate integrally, and the rotation of the sprocket 13 is transmitted to the cam shaft 16.

Since they are helically spline-engaged with each other, when the cylinder 34 slides in the rotating shaft direction, thrust is generated in the meshing portion, and the camshaft 1
6 can be slid in the rotational direction. That is, the rotation phase between the sprocket 13 and the cam shaft 16 can be changed. In this embodiment, the hydraulic device 50 is used to slide the cylinder 34, and therefore two hydraulic chambers 35 and 36 are formed inside the adjusting mechanism 20.

In FIG. 3, the left side is a hydraulic chamber 3 for advance operation.
5, the right side is the hydraulic chamber 36 for retarding operation, and the cylinder 3
4 can be slid in the axial direction according to the operating hydraulic pressure supplied to each hydraulic chamber. In addition, an oil seal is appropriately applied to each part of the region forming the hydraulic chambers 35 and 36. Hydraulic system 50
Is an oil pan 51 that stores hydraulic oil (see FIG. 2),
It is provided with a hydraulic pump 52 driven by engine power, a spool valve 53 that distributes hydraulic oil pumped from the hydraulic pump 52 to each hydraulic chamber, and a hydraulic path that communicates between these. In FIG. 3, 37 is a hydraulic path between the hydraulic pump 52 and the spool valve 53, 38 is a hydraulic path between the spool valve 53 and an oil pan, 39 is a hydraulic path between the spool valve 53 and the hydraulic chamber 35, and 40 is a spool valve 53-. The hydraulic path between the hydraulic chambers 36 is shown.

The passage of the hydraulic passage 40 is a region surrounded by the bolt 41 and the camshaft sleeve 23 from a T-shaped communication passage 40a formed in a bolt 41 for fixing the ring plate 31 to the housing 22. The hydraulic passage 36 extends through the hydraulic passage 40c formed in the camshaft sleeve 23 via the hydraulic passage 40b. Next, referring to FIG. 4, the spool valve 53
The operation of will be described.

In FIG. 4, 54 is a cylinder, 55 is a spool that slides in the cylinder 54, and 56 is the control unit 70.
A linear solenoid that slides the spool 55 in accordance with a control signal from the reference numeral 57 is a spring that biases the spool 55 in the opposite direction to the driving direction of the linear solenoid 56. The cylinder 54 has a hydraulic oil supply port 58 that communicates with the hydraulic pump 52, a hydraulic oil discharge port 59 that communicates with an oil pan, and a hydraulic port 6 that communicates with the hydraulic chamber 35.
0, and a hydraulic port 61 communicating with the hydraulic chamber 36 is formed.

The amount of hydraulic oil in each of the hydraulic chambers 35 and 36 is increased / decreased by the spool 55 sliding to continuously change the opening of each hydraulic port, and the opening is supplied to the linear solenoid 56. It is determined by the current value. Therefore, the control unit 70 generates a control signal with a duty value and outputs the control signal to the current control circuit, and the current control circuit supplies the current corresponding to the duty value to the linear solenoid 56.

FIG. 4 shows a typical state example of the spool valve 53. FIG. 4A is an example when the duty value of the control signal in the control unit 70 is about 100%. The spool 55 is driven to the right end of the cylinder by the linear solenoid 56, between the supply port 58 and the hydraulic port 60, and The state in which the hydraulic port 61 and the discharge port 59 are in communication is shown. At this time, the hydraulic oil is supplied to the hydraulic chamber 35 through the hydraulic passage 39, while the hydraulic oil is discharged from the hydraulic chamber 36. As a result, the cylinder 34 shown in FIG. 3 moves to the right in the drawing, and the phase of the cam shaft 16 with respect to the sprocket 13 advances so that advance angle control is performed.

In FIG. 4B, the same duty value is about 50%.
In this case, the forces of the opposing linear solenoid 56 and spring 57 are balanced, the spool 55 is maintained at a position to close both hydraulic ports 60, 61, and the hydraulic oil is supplied to the hydraulic chambers 35, 36. And the state that the discharge is not performed. At this time, when the hydraulic oil does not leak from the hydraulic chambers 35 and 36, the cylinder 34 is held at the current position, and the phase between the sprocket 13 and the cam shaft 16 is maintained at the current state.

FIG. 4C shows an example when the duty value is about 0%. The spool 55 is biased to the left end of the cylinder by the spring 57, and the supply port 58-hydraulic port 6 is shown.
1 and a state in which the hydraulic port 60 and the discharge port 59 communicate with each other. At this time, the hydraulic oil is supplied to the hydraulic chamber 36, while the hydraulic oil is discharged from the hydraulic chamber 35, so that the cylinder 34 moves to the left in the drawing and the phase of the camshaft 16 with respect to the sprocket 13 is delayed so that the retard control is performed. Becomes

Next, the control operation of the control unit 70 will be described with reference to FIGS. FIG. 5A shows a control system executed by the control unit 70. The controller 72 is a controller for PD operation, and the deviation e between the target camshaft advance angle value r determined based on the operating state of the engine and the current camshaft advance angle value y is input. The controller 72 determines the operation amount u by a duty value based on a flowchart described later, and outputs the operation amount u to a controlled object 74 including a hydraulic device and a phase adjusting mechanism. The manipulated variable u is generated by a pulse width modulation signal and supplied to the linear solenoid via the current control circuit. This adjusts the hydraulic oil in the hydraulic chamber,
The cam shaft is displaced in the rotation direction according to the amount of hydraulic oil.
The camshaft advance value y at this time is detected from the controlled object 74.

The central theoretical value represented by the solid line in the graph showing the duty value (u) -camshaft advance speed (u1) characteristic in the controlled object of FIG. 5 (a) is a steady state such as manufacturing tolerance and aging. It has been experimentally confirmed that the target disturbance causes a parallel displacement as shown by the dotted line. This steady disturbance is except for the duty values near 0% and 100%,
It can be replaced by a constant value of the model shown in FIG.
FIG. 6 is a model of a state in which the steady disturbance d is added to the control system.

In this embodiment, it is particularly effective in the low frequency region described in the document "The latest technology of motion control (1) -Research on machinery, Vol. 45, No. 1 (1993)", that is, when the disturbance is constant. By applying the "disturbance estimation observer", the steady disturbance d such as manufacturing tolerance and change with time can be accurately estimated, and a control system that is not affected by the steady disturbance d can be configured.

A method of constructing the disturbance estimation observer will be described below. First, FIG. 7 shows a dynamic model of a controlled object when a steady disturbance (hereinafter referred to as disturbance) d, which is a factor of variation in flow rate characteristics, is applied to the solenoid valve. In this model, the duty value (u), the disturbance (d), and the camshaft advance value (y) have the relationship described in Expression 1, and when the disturbance d is modified from this relational expression, Expression 2 is obtained. .

[0029]

[Equation 1]

[0030]

[Equation 2] Note that K and L are constants, in particular K represents the flow rate characteristic shown in FIG. 6 and L represents the dead time. Here, s is a Laplace operator.

Rewriting Equation 2 into a control system model, FIG.
It is expressed as. Further, from Equation 2 and FIG. 8, theoretically, the disturbance can be detected as the disturbance dd. However, the disturbance d
Since the differential term s is included in d, it is currently impossible to detect a true disturbance and reflect it in the control system because it is greatly affected by noise. Therefore, in order to detect the true disturbance dr, the low-pass filter represented by Expression 3 is inserted.

[0032]

(Equation 3) Solving for the true disturbance dr in order to insert Equation 3 into the control system yields Equation 4.

[0033]

[Equation 4] When the disturbance estimation observer that detects the true disturbance dr from the result of Expression 4 is inserted into the control system, the result is as shown in FIG. 9, and the processing executed by the control unit 70 according to the control system is shown in FIGS. 10 and 11.

Χ ₀ and χ ₁ in FIG. 9 mean the following equations.

[0035]

(Equation 5) FIG. 10 shows a learning control process executed by the control unit 70 (for example, every 20 ms). k indicates a sampling time every 20 ms.

First, each state signal in the engine is fetched from the above-mentioned various sensors (step 100), and the camshaft advance value y (k) at the engine operating state and the time point k is used as a transition of the difference between the crank position and the camshaft position. Calculate from the amount (step 11
0), the target advance value r (k) is calculated from the map value of the load and the rotation speed of the internal combustion engine (step 120). Then, the deviation e between the target advance value r (k) and the current camshaft advance value y (k)
(K) is calculated by Equation 6 (step 130), and the output u ₀ (k) of the basic controller is calculated by Equation 7 (step 140). The final duty value u (k) is calculated by using Equation 8 using the controller output u ₀ (k) calculated here and the disturbance learning value dr (k) obtained using the processing shown in FIG. It is calculated and output (steps 150 and 160).

[0037]

## EQU00006 ## e (k) = r (k) -y (k)

[0038]

[Equation 7] u ₀ (k) = K _P · e (k) + K _D · [e
(K) -e (k-1)]

[0039]

Equation 8] _{u (k) = u 0 (} k) + dr (k) + 50% Here, K _P, K _D is the feedback gain, each separate value according to the load required for the valve operation timing control It may be set in. Here, 50% indicates the design center value of the solenoid valve drive duty value for holding the cam shaft at a predetermined position.

In the disturbance dr learning process (executed every 20 ms, for example) shown in FIG. 11, the true disturbance dr is calculated from the following equations 9 to 11 based on equation 4.

[0041]

[Equation 9]

[0042]

[Equation 10] χ ₁ (k) = a · χ ₁ (k−1) + b · χ ₀ (k)

[0043]

[Equation 11] Since the driving means has a dead time of about 60 ms, there is a delay of 3 samples with the operation synchronization being 20 ms. In order to correct this delay, u ₀ (k-3) 3 samples before is used (Equation 9). Formula 10 is the result of low-pass filter processing on χ ₀ (k).

The present invention is not limited to the above embodiment, and the following modifications or expansions are possible.
In this embodiment, the flow rate characteristic is linearly approximated with a slope K, and this is used as a model constant of the design center value. When the non-linearity of the flow rate characteristic is very strong, learning may be performed only in the linear portion, or the flow rate characteristic may be linearly approximated.

When the learned value dr varies greatly, a change amount limiting process such as a smoothing process may be added to dr.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is a configuration diagram of an engine to which the present device is applied.

FIG. 3 is a sectional view of a phase adjusting mechanism.

FIG. 4A is a diagram showing a state of the spool valve when the drive duty value is 100%. (B) is a diagram showing a state of the spool valve when the drive duty value is 50%. FIG. 7C is a diagram showing a state of the spool valve when the drive duty value is 0%.

FIG. 5A is a model diagram of a control system showing a flow rate characteristic of a controlled object. (B) is a model diagram of a control system showing a state in which the disturbance d is added to the controlled object.

FIG. 6 is a model diagram of a control target representing the characteristics of a disturbance d applied to the control target.

FIG. 7 is a dynamic model diagram of a control target when a steady disturbance is applied to the solenoid valve.

FIG. 8 is a control system model diagram rewritten so that a disturbance can be detected from the control system.

FIG. 9 is a control system model diagram in which a learning control system is configured by inserting a low-pass filter into the detected disturbance.

FIG. 10 is a processing diagram of learning control executed according to a model.

FIG. 11 is a disturbance learning value calculation processing diagram.

[Explanation of symbols]

 10 Engine Main Body 11 Crank Shaft 13 Exhaust Valve Sprocket 15 Cam Shaft 17 Crank Position Detection Sensor 18 Cam Shaft Position Detection Sensor 20 Phase Adjustment Mechanism 50 Hydraulic Device 53 Spool Valve 56 Linear Solenoid 70 Control Section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02D 45/00 340 C

Claims (2)

[Claims] 1. A phase adjusting mechanism provided in a rotation transmission system from a crankshaft to a camshaft of an internal combustion engine for changing a rotational phase difference between the two shafts, and a drive for driving the phase adjusting mechanism. Means, various sensors provided in each part of the internal combustion engine to indicate the operating state of the engine, and rotational phase difference detecting means for calculating the actual phase difference angle between the two shafts based on the operating state amount detected by the sensor. A target value determining means for determining a target value of the rotational phase difference based on the operating state amount detected by the sensor, and a control value for matching the phase difference angle with the target value of the rotational phase difference. Control means for outputting to the driving means, learning means for learning a steady disturbance by a dynamic characteristic model of the driving means, the rotational phase difference and an output value to the driving means, and a learning value of the learning means The control value The valve timing control apparatus for an internal combustion engine and a correcting correcting means. 2. The valve timing control device according to claim 1, wherein the dynamic characteristic model is a model on the assumption that a steady disturbance is added to a theoretical value of a center of a driving unit for driving the phase adjusting mechanism.