JP3344921B2 - Valve timing control device for internal combustion engine - 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 apparatus for an internal combustion engine for variably controlling the opening and closing timing of an intake valve and an exhaust valve of an automobile 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 according to the operating state of an automobile engine or the like is known from, for example, JP-A-7-332118. Have been.

[0003] This type of valve timing control device is driven by a rotation phase variable means for generating a phase difference in the rotation phase between a crankshaft and a camshaft, and a hydraulic pressure supplied and discharged from a hydraulic pressure source such as a hydraulic pump. An actuator such as a hydraulic cylinder, and a valve body which is disposed between the actuator and the hydraulic pressure source, and normally keeps the valve body at a neutral position with a dead zone having a fixed width, and applies hydraulic pressure from the hydraulic pressure source to the actuator. A control valve mechanism such as a spool valve for slidingly displacing the valve body from the neutral position when supplying and discharging, and a valve control for slidingly displacing the valve body of the control valve mechanism in accordance with a control signal to operate the actuator. Means.

[0004] The valve timing control device includes:
The actuator is operated by the control valve mechanism,
The rotation phase variable means is driven by the actuator,
The opening and closing timing of the intake and exhaust valves of the engine is variably controlled.

[0005]

In the valve timing control apparatus according to the prior art, a deviation between a target value for operating the actuator and a detection value corresponding to the current operation state of the actuator is determined, and the deviation with respect to this deviation is determined. The proportional operation and the compensation operation for the dead zone are performed, and the valve element of the control valve is driven based on these calculated values, thereby performing feedback control of the actuator.

However, when an electromagnetic actuator such as a proportional solenoid for driving the valve element of the control valve is heated for a long time or the like, thermal resistance is generated in the coil portion of the electromagnetic actuator. May gradually decrease.

Therefore, in the prior art, when the valve element of the control valve mechanism is returned to the neutral position in order to shift the actuator from the operating state to the stopped state, if the return position (neutral position) of the valve element is shifted, At the time of the next drive, the sliding displacement amount of the valve body in response to the control signal changes, and the flow rate of the liquid supplied to and discharged from the actuator also changes. This makes it difficult to accurately and stably drive the actuator to the target position, and a steady-state deviation occurs between the detection value of the rotation phase variable means driven by the actuator and the target value, and the valve timing is reduced. There is a problem that it cannot be controlled properly.

In addition, the return position of the valve element may be shifted, for example, in the range of a dead zone due to a manufacturing error of the valve element or the like, and the actuator control device is used for valve timing control of an engine or the like that requires accurate control. In such a case, there is a problem that it becomes difficult to drive the engine with optimal valve timing.

In order to correct the deviation of the return position of the valve element, the present inventor performs an integral operation on the deviation in addition to a proportional operation on the deviation and a compensation operation for dead zone compensation. The drive control of the valve body of the control valve was studied based on the above.

However, in this case, for example, when the engine speed falls into a low rotation range, the value calculated by the integration operation becomes excessively large, and an overshoot may occur in the actuator. There is an unsolved problem that it is difficult to convert.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention can prevent an operation value by an integral operation from becoming excessive, optimize the operation of an actuator, and reduce a return position of a valve body. In the case where a shift occurs, the position shift can be corrected in a short time, the actuator can be quickly moved to the target position and a substantial stop state can be achieved, and the reliability and stability of the feedback control can be improved. An object of the present invention is to provide a valve timing control device for an internal combustion engine as described above.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for controlling the valve timing of an internal combustion engine variably, by adding a phase difference to the rotational phase between a crankshaft and a camshaft of the internal combustion engine. A rotation phase variable means to be generated, an actuator driven and controlled by a hydraulic pressure supplied and discharged from a hydraulic pressure source for operating the rotation phase variable means, and a hydraulic pressure source disposed between the actuator and the hydraulic pressure source. A control valve mechanism that constantly holds the valve body at a neutral position with a fixed width dead zone, and slides and displaces the valve body from the neutral position when supplying and discharging hydraulic pressure from the hydraulic pressure source to the actuator; and In order to operate, the present invention is applied to a valve timing control device for an internal combustion engine, which comprises valve control means for slidingly displacing a valve element of the control valve mechanism in accordance with a control signal.

[0013] A feature of the structure adopted by the first aspect of the present invention is that the valve control means operates the rotation phase variable means so as to change the valve timing in accordance with the operation state of the internal combustion engine. Target value setting means for setting a target value for causing a rotation phase of the crankshaft
The crank position detector when
Reference signal and camshaft rotation phase output from
Comes out of the cam position detector when
An operation amount of the rotation phase variable means is calculated as a detection value based on the input second reference signal, and the first and second base signals are calculated.
An operation quantity operation for updating the detection value each time the reference signal is updated.
Operation detecting means comprising a calculating circuit ; deviation calculating means for calculating a deviation between a target value by the target value setting means and a detection value by the operation detecting means; and a proportional operation for performing a proportional operation on the deviation from the deviation calculating means. Means, an integral operation means for performing an integral operation on the deviation from the deviation operation means, and a compensation operation means for compensating and operating the dead zone for the deviation by the deviation operation means in order to perform dead zone compensation of the control valve mechanism. When the time when the detection value is updated by the operation detection means is determined as the detection time, and when the detection value is detected by the detection time determination means, Setting a control signal to be output to the control valve mechanism on the basis of respective calculation values of the proportional calculation means, the integration calculation means, and the compensation calculation means; When it is determined that the time lies in the structure of the output signal setting means for setting the control signal from each of the calculated values by the proportional operation means and compensation computation section.

With the above arrangement, the valve timing is feedback-controlled in accordance with the deviation between the target value set by the target value setting means and the detection value detected by the operation detection means. The integral calculation means calculates a calculation value for compensating for the deviation of the return position by integrating the deviation, and the compensation calculation means sets the deviation to a positive value and a negative value. It is possible to calculate an operation value for slidingly displacing the valve body by a displacement amount corresponding to the width of the dead zone when switching.

Only when the detection time is judged by the detection time judgment means, the operation value by the integration operation means is output, and at the non-detection time, the output of the operation value by the integration operation means can be interrupted. Can be prevented from becoming excessive.

[0016]

Further, to detect the rotational phase of the crankshaft by the crank position sensor, since detecting the rotation phase of the camshaft by the cam position sensor, at the operating amount calculation circuit includes a crankshaft and the camshaft by these detection results Can be calculated, and the operation amount of the rotation phase varying means can be calculated from the phase difference.

[0018]

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

FIGS. 1 to 14 show an example in which the valve timing control device for an internal combustion engine according to the embodiment of the present invention is applied to an automobile engine.

In FIG. 1, reference numeral 1 denotes a crankshaft as an output shaft rotatably provided on an engine body (not shown) as an internal combustion engine, and a small-diameter pulley 1A is integrally attached to one end of the crankshaft. . The crankshaft 1 is provided with a later-described crank angle sensor 41 for detecting the rotation phase α.

Reference numeral 2 denotes a drive shaft for transmitting the rotational driving force of the crankshaft 1 to a camshaft 4 described later.
The drive shaft 2 has a center O2 -O on the engine body side.
The large-diameter pulley 2A of the drive shaft 2 is connected to the 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. Makes 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.

Reference numeral 5 denotes an eccentric disk 9
The connecting arm 5 is provided at the other end of the drive shaft 2 and rotates integrally with the drive shaft 2. An engaging groove 5A extending in the radial direction is formed in the connecting arm 5, and an engaging pin 9A of the eccentric disk 9 is engaged in the engaging groove 5A.

Reference numeral 6 denotes another connecting arm provided at one end of the camshaft 4. The connecting arm 6 has an engaging groove 6 A extending in the radial direction, and the engaging groove 6 A has an eccentric disk 9. 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. ing.

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 rotation phase β of the camshaft 4 is shown in FIG. As shown, the crankshaft 1
Is changed relative to the rotation phase α, and a phase difference Φ is generated between the rotation 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. 2, 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. A portion 8B and a pair of engaging claws 8C, 8C integrally formed on the other end side of the annular portion 8B.

Reference numeral 9 denotes the drive shaft 2 connected to the camshaft 4
The eccentric disk 9 has an engaging pin 9A protruding from one side and an engaging pin 9B protruding from the other side. The engaging pins 9A and 9B
As shown in FIG. 2, they are arranged at positions radially opposed to each other with the center O2-O2 of the eccentric disk 9 interposed therebetween.

The eccentric disk 9 is mounted on the disk holder 8
The engagement pins 9A and 9B are slidably engaged in the engagement grooves 5A and 6A of the connecting arms 5 and 6, respectively. ing. Thereby, the drive shaft 2 and the camshaft 4
Are connected to each other via the connecting arms 5 and 6 and the eccentric disk 9, and in this state, the eccentric disk 9 is connected between the connecting arms 5 and 6 by the camshaft 4 (drive shaft 2).
Are relatively displaceable in the radial direction.

Reference numeral 10 denotes a control shaft for eccentrically moving the eccentric disk 9.
The control shaft 10 is provided rotatably about an axis O3-O3 on the engine body side, and a circular cam 10A is eccentrically provided on one end side of the control shaft 10. And
The cam 10A is slidably disposed between the engagement claws 8C of the disk holder 8, and the control shaft 10 is connected to the hydraulic cylinder 12 via the connection arm 11.

Reference numeral 11 denotes a connecting arm for connecting the control shaft 10 to the rod 12C of the hydraulic cylinder 12. The connecting arm 11 is provided at the other end of the control shaft 10, and rotates integrally with the control shaft 10. The connecting arm 11 has an engaging groove 1 extending in a radial direction.
1A is formed, and an engaging pin 12F of a rod 12C is engaged with the engaging groove 11A.

Reference numeral 12 denotes a hydraulic cylinder as a linear actuator for rotating the control shaft 10. The hydraulic cylinder 12 is slidably provided in the cylinder 12A as shown in FIG. And a rod 12 having one end fixed to the piston 12B and the other end protruding outside the cylinder 12A.
C. And the hydraulic cylinder 12
Is connected to a hydraulic pump 15 serving as a hydraulic pressure source together with the tank 14 via pipes 13A and 13B, and is connected to two oil chambers 12D and 12E defined by a piston 12B.
The rod 12C is expanded and contracted in the directions indicated by the arrows A and B by supplying and discharging the pressure oil through A and 13B.

The rod 12C is provided with an engaging pin 12F projecting therefrom.
Is slidably engaged in the engagement groove 11A. The control shaft 10 is provided with the hydraulic cylinder 1
2 rod 12C is rotated by sliding displacement in the directions of arrows A and B, and the control shaft 10C is rotated.
Swings the disk holder 8 together with the eccentric disk 9 in the directions of arrows C and D with the eccentric disk 9 via the cam 10A.

Reference numeral 16 denotes a control valve device as a control valve mechanism, 1
Reference numeral 7 denotes a spool valve constituting a main body of the control valve device 16. The spool valve 17 has a substantially cylindrical valve casing 18.
4 is formed with a spool sliding hole 18A in which the sliding member 4 is slidably inserted. A pump port 19, a tank port 20, and a pair of outflow / inflow ports 21 and 22 are provided in the valve casing 18 in the axial direction of the spool sliding hole 18A. A drain port 23 is provided.

Here, the pump port 19 is connected to the hydraulic pump 1
5 and the tank port 20 is connected to the tank 14. The inflow / outflow port 21 is connected to the hydraulic cylinder 1
The inlet / outlet port 22 is connected to the supply / discharge port 12 </ b> H of the hydraulic cylinder 12. Also,
The inflow / outflow ports 21 and 22 are formed as rectangular ports, for example, as shown in FIG.
3 is connected to the tank 14.

Numeral 24 denotes a spool as a valve body which is displaceably provided in a spool sliding hole 18A of the valve casing 18. The spool 24 has two lands 24A, 2A.
4B, the land 24A opens and closes the inflow / outflow port 21, and the land 24B opens and closes the inflow / outflow port 22. The spool 24 is slid in the directions indicated by arrows E and F in proportion to the duty ratio of the PWM signal output from the control unit 28 by an electromagnetic actuator 27 described later. A spring chamber 25 communicating with the drain port 23 is formed between one end of the spool 24 and the valve casing 18.
A spring 26 that constantly biases the spool 24 in the direction indicated by the arrow F is provided in 5.

When the spool 24 is at the neutral position, the land 24A of the spool 24 completely closes the inflow / outflow port 21 as shown in FIG.
Completely closes the inflow / outflow port 22. The width of the lands 24A and 24B of the spool 24 is larger than that of the inflow / outflow ports 21 and 22 by a certain dimension δ, so that the stability when the ports are closed is ensured. For this reason, between the lands 24A, 24B of the spool 24 and the inflow / outflow ports 21, 22 of the valve casing 18, even if the spool 24 is slightly slid at the neutral position, the inflow / outflow ports 21, 22 are opened. A dead zone (corresponding to the dimension δ) having a constant width is formed.

Numeral 27 denotes an electromagnetic actuator as a spool driving means for driving and displacing the spool 24. The electromagnetic actuator 27 comprises an electromagnetic proportional solenoid.
Case 27A attached to the other end of valve casing 18
And a coil part 27B provided in the case 27A;
And a drive rod 27C provided displaceably on the inner peripheral side of the coil portion 27B.

The control valve device 16 is connected to the valve casing 1.
8, a spool 24, an electromagnetic actuator 27, and the like, for variably controlling the flow rate and direction of pressure oil to be supplied to and discharged from the hydraulic cylinder 12. That is, the control valve device 16 causes the electromagnetic actuator 27 to move the spool 24 to the valve casing 1.
8 is displaced in the sliding hole 18A of the spool to communicate and shut off the inflow / outflow ports 21 and 22, thereby supplying the hydraulic oil from the hydraulic pump 15 to the hydraulic cylinder 12 through the pump port 19, The pressure oil in the hydraulic cylinder 12 is discharged to the tank 14 via the tank port 20 and the drain port 23.

Reference numeral 28 denotes a control unit which constitutes valve control means together with a crank angle sensor 41 and a cam position sensor 42, which will be described later. The control unit 28 is constituted by, for example, a microcomputer. A storage unit 28A is provided for controlling the driving of the electromagnetic actuator 27.

As shown in FIG. 6, a deviation calculation circuit 29, a proportional calculation circuit 30, an integration calculation circuit 31, a compensation calculation circuit 32,
A neutral position setting circuit 33, a detection time determination circuit 34, an output signal setting circuit 35, a target value setting circuit 39, and an operation amount calculation circuit 40 are provided. The storage unit 28A of the control unit 28 stores a program for a spool valve control process as shown in FIG. 9, a constant Kp which is a gain of a proportional operation, a constant K0 which will be described later for an integral operation, A constant Kb and a detection flag F used for the dead zone compensation calculation are stored in advance. The input side of the control unit 28 is connected to a crank angle sensor 41 and a cam position sensor 42 described later, and the output side is connected to the electromagnetic actuator 27 of the spool valve 17 and the like.

Here, the constant Kb is a numerical value corresponding to the constant dimension δ of the dead zone.
By outputting a signal corresponding to b, dead zone compensation can be performed. The constants Kp and K0 are numerical values obtained by experiments. For example, the constant Kp is about 1000 times the constant K0. Further, the detection flag F is set to 1 (F = 1) when the detection time is determined by the detection time determination circuit 34 to be described later, and is zero (F = 0) when the detection time determination circuit 34 determines that the detection is not a detection time.
Is set to

Reference numeral 29 denotes a deviation calculation circuit as deviation calculation means. The deviation calculation circuit 29 is a deviation e between a target value r from the target value setting circuit 39 and a detection value y from the operation amount calculation circuit 40.
Is calculated. Reference numeral 30 denotes a proportional operation circuit serving as a proportional operation means. The proportional operation circuit 30 outputs a proportional operation value u1 proportional to the deviation e output from the deviation operation circuit 29.

Numeral 31 denotes an integral operation circuit as integral operation means, which integrates the deviation e with respect to time,
And outputs an integral operation value u2 corresponding to the integral value of. Reference numeral 32 denotes a compensation operation circuit 32 serving as compensation operation means. The compensation operation circuit 32 outputs a compensation operation value u3 for performing a compensation operation for the above-mentioned dead zone with respect to the deviation e. A neutral position setting circuit 33 sets a neutral position of the spool 24. The neutral position setting circuit 33 holds the spool 24 at the neutral position.
For example, a constant neutral position set value u4 corresponding to a duty ratio of 50% is constantly output.

Numeral 34 denotes a detection time judgment circuit as detection time judgment means connected to the crank angle sensor 41 and the cam position sensor 42. The detection time judgment circuit 34 outputs an output from the crank angle sensor 41 as shown in FIG. Reference signal S1 and the reference signal S2 output from the cam position sensor 42.
The detection flag F is set to 1 (F = 1) by determining when the detection value y by the operation amount calculation circuit 40 described later is updated based on the detection time, and otherwise, it is determined as the non-detection time. The detection flag F to zero (F =
0).

Reference numeral 35 denotes an output signal setting circuit as output signal setting means. The output signal setting circuit 35 includes an integral gain adjustment circuit 36, an addition operation circuit 37, and a PWM conversion circuit 3.
8. Then, the integral gain adjusting circuit 36 sets a coefficient Ki, which becomes a gain of the integral operation, to a constant K0 (Ki = K0) when the detection time determination circuit 34 determines that the detection time is reached.
Is set to zero, and when it is determined that the time is the non-detection point, the coefficient Ki serving as the gain of the integration operation is set to zero (Ki = 0).

When the detection time determination circuit 34 determines that the detection time is reached, the addition operation circuit 37 adds the proportional operation value u1, the integral operation value u2, the compensation operation value u3, and the neutral position set value u4 to the addition operation value u. Is output, and when it is determined that the time is the non-detection point, an addition operation value u obtained by adding the proportional operation value u1, the compensation operation value u3, and the neutral position set value u4 is added.
Is output.

Then, the PWM conversion circuit 38 determines the duty ratio of the pulse width modulation signal (PWM signal) based on the addition operation value u output from the addition operation circuit 37, and converts the duty ratio in accordance with the duty ratio. PW as signal
The M signal is output to the electromagnetic actuator 27 of the control valve device 16.

Reference numeral 39 denotes a target value setting circuit as target value setting means for calculating an optimal valve timing based on the engine speed N and the like. The target value setting circuit 39 is a target of the control shaft 10 corresponding to the optimal valve timing. The rotation angle is output as a target value r.

Reference numeral 40 denotes an operation amount calculation circuit which constitutes operation detection means together with a crank angle sensor 41 as a crank position detector and a cam position sensor 42 as a cam position detector. And the second reference signal S1 from the cam position sensor 42.
Then, the actual rotation angle θ (see FIG. 3) of the control shaft 10 is calculated as the detection value y based on the reference signal S2.

Here, the crank angle sensor 41 is provided adjacent to the crankshaft 1 as shown in FIG. 7, and detects when the rotational phase α of the crankshaft 1 reaches a predetermined rotational phase. The first reference signal S1 is output as shown in FIG.

The cam position sensor 42 is provided on the camshaft 4 side, detects when the rotational phase β of the camshaft 4 reaches a predetermined rotational phase, and detects the second rotational phase as shown in FIG. A signal S2 is output, and the crank angle sensor 41 and the cam position sensor 42
Is configured to output each of the reference signals S1 and S2 only once during one rotation.

When a phase difference .PHI. Occurs between the crankshaft 1 and the camshaft 4 due to the eccentric mechanism 7, the second reference signal S2 of the cam position sensor 42 becomes S2 in FIG.
As shown at ', the signal is output with a delay of, for example, a time ΔT from the first reference signal S1 of the crank angle sensor 41. As a result, the operation amount calculating circuit 40 outputs each reference signal S1
, S2 'and the phase difference Φ based on the engine speed N.

[0054]

Calculated as Φ = k × ΔT × N (where k is a constant). Further, the operation amount calculation circuit 40 calculates the actual rotation angle θ (see FIG. 3) of the control shaft 10 as the detection value y based on the phase difference Φ.

Thus, the control unit 28
Operates the hydraulic cylinder 12 so that the detected value y matches the target value r output from the target value setting circuit 39, and performs feedback control of the control shaft 10.

The valve timing control device for an internal combustion engine according to the present embodiment has the above-described configuration. Next, the operation of the device will be described.

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 arm 5 and the eccentric disk 9 rotate in the disk holder 8 in the direction of arrow G in FIG. This rotational driving force is applied to the eccentric disk 9
Is transmitted to the camshaft 4 via the engaging pin 9B and the connecting arm 6, and the camshaft 4 opens and closes the intake valves when the rotation phase β becomes a predetermined rotation phase.

When the opening / closing timing of the intake valve is changed, the target rotation angle of the control shaft 10 corresponding to the optimum valve timing is output from the target value setting circuit 39 in the control unit 28 as the target value r. Thereby, the control unit 28 moves the rod 12C of the hydraulic cylinder 12 in the directions indicated by the arrows A and B as shown in FIG. 2 so that the actual rotation angle θ of the control shaft 10 matches the target value r. At this time, the control shaft 10 which engages with the rod 12C via the connecting arm 11 and the like rotates in the directions of arrows C and D, and the eccentric disk 9 moves the camshaft 4 between the connecting arms 5 and 6, as shown in FIG. Relative displacement in the radial direction and the center O2 −
O2 is eccentric from the center O1-O1 of the camshaft 4 by an eccentricity .epsilon.

As a result, a phase difference Φ occurs between the rotation phase β of the camshaft 4 and the rotation phase α of the crankshaft 1, and the opening / closing timing of the intake valve opened / closed by the camshaft 4 depends on the phase difference Φ. Therefore, by changing the phase difference Φ to a desired value, the opening / closing timing of the intake valve can be appropriately controlled.

Next, the valve timing control processing by the control unit 28 will be described with reference to FIG.

First, in step 1, the neutral position setting value u4 output from the neutral position setting circuit 33 is read. In step 2, the target value setting circuit 39 responds to the optimum valve timing based on the engine speed N and the like. The calculated target rotation angle of the control shaft 10 is calculated as a target value r.

Next, in step 3, the detection time point is determined by the detection time point determination circuit 34 based on the first reference signal S1 from the crank angle sensor 41 and the second reference signal S2 from the cam position sensor 42. Then, the operation amount calculating circuit 40 generates the first reference signal S1 and the second reference signal S2.
And the actual rotation angle θ of the control shaft 10 is calculated as the detected value y. Then, in step 4, the deviation calculating circuit 29 calculates a deviation e (e = ry) between the target value r and the detected value y.

Next, in step 5, the integral gain adjustment processing shown in FIG. 11 is performed, and when the detection time determination circuit 34 determines that the detection time has been reached, the coefficient Ki serving as the gain of the integration operation is set to K0 (Ki = K0). , The coefficient Ki is set to zero (Ki = 0).

At step 6, the integral operation value u is calculated by multiplying the value obtained by the time integration of the deviation e by the coefficient Ki.
2 (u2 = u2 + Ki * e) is calculated.

Next, in step 7, the constant Kp is read from the storage unit 28A, and the proportional operation circuit 30 calculates the proportional operation value u1 (u1 = K1) which is the product of the constant Kp and the deviation e.
p × e) is calculated.

Next, in step 8, the deviation e is zero (e =
0), and if "YES" is determined, since the rod 12C of the hydraulic cylinder 12 has reached the target position, the routine proceeds to step 12, where the compensation calculation value u3 for compensating for the dead zone is calculated. The value is set to zero (u3 = 0), and in steps 13 and 14, which will be described later, processing is performed to return the spool 24 to the neutral position.

If "NO" is determined in the step 8, the process proceeds to a step 9, where the deviation e is a positive value (e> 0).
The control shaft 10 is excessively rotated in the direction indicated by the arrow D, and the rod 12C of the hydraulic cylinder 12 is reduced in the direction indicated by the arrow B from the target position. Too much, step 1
Moving to 0, the compensation operation value u3 is set to Kb (u3 = Kb). Then, by the processing in steps 13 and 14, the spool 24 slides and displaces in the direction of arrow E, and the pressure oil from the hydraulic pump 15 is supplied into the oil chamber 12D of the hydraulic cylinder 12.

On the other hand, if "NO" is determined in the step 9, the deviation e becomes a negative value (e <0), and the control shaft 10 is excessively rotated in the arrow C direction. 12C shows arrow A more than target position
Since it has been excessively expanded in the direction, the process proceeds to step 11 and the compensation operation value u3 is set to -Kb (u3 = -Kb). Then, by the processing of steps 13 and 14, the spool 24
Is slid in the direction of arrow F, and the pressure oil from the hydraulic pump 15 is supplied into the oil chamber 12E of the hydraulic cylinder 12.

Next, at step 13, the proportional operation value u1
, Integral operation value u2, compensation operation value u3 and neutral position set value u4, and an addition operation value u (u = u1 + u2 + u3 + u4) corresponding to the duty ratio of the PWM signal.
Is calculated.

Then, in step 14, the addition operation value u is converted into a PWM signal having a duty ratio corresponding thereto, and this PWM signal is output to the electromagnetic actuator 27 to slide the spool 24. Thereby, the pressure oil supplied to the hydraulic cylinder 12 is controlled, and the control shaft 10 rotates in a direction to reduce the deviation e,
The engine can be driven with optimal valve timing.

Next, the calculation processing of the detection value y and the detection time determination processing by the detection time determination circuit 34 and the operation amount calculation circuit 40 will be described with reference to FIG.

First, in step 21, it is determined whether or not the first reference signal S1 from the crank angle sensor 41 has been detected.
The timer T for measuring the time between the first reference signal S1 and the second reference signal S2 is set to zero (T = 0), and the routine goes to step 23.

On the other hand, if "NO" is determined in the step 21, the process proceeds to a step 23, where it is determined whether or not the second reference signal S2 from the cam position sensor 42 is detected.
When it is determined as "NO" in the step 23, it is the time of non-detection, so the process proceeds to a step 27, where the detection flag F is set to zero (F = 0), and the process returns in the step 28.

If "YES" is determined in the step 23, the detection value y is updated and the detection flag F is set to 1 (F = 1).
And at step 25 the first reference signal S1
The time ΔT between the second reference signal S2 and the second reference signal S2 is set to the value of the timer T. Then, in step 26, the operation amount calculation circuit 40 calculates the equation (1) based on the time ΔT and the engine speed N.
, The phase difference Φ between the crankshaft 1 and the camshaft 4 is calculated, the actual rotation angle θ of the control shaft 10 corresponding to the phase difference Φ is calculated, and the detected value y is updated.

Next, an integral operation gain adjustment process for adjusting a coefficient Ki serving as an integral operation gain based on the judgment result of the detection time judgment circuit 34 will be described with reference to FIG.

First, in step 31, it is determined whether or not the detection flag F is 1 (F = 1). If "YES" is determined, the detection is in effect, so the flow proceeds to step 32 in which the gain of the integration operation is calculated. The coefficient Ki is expressed as K0 (Ki = K0)
, And at step 33, the detection flag F is set to zero (F = 0), and the routine proceeds to step 35 and returns.

On the other hand, if "NO" is determined in step 31, it is the time of non-detection, so that the process proceeds to step 34, where the coefficient Ki serving as the gain of the integration operation is fixed to zero (Ki = 0). Move and return.

Here, the operations of the proportional operation circuit 30, the integral operation circuit 31, the compensation operation circuit 32, the detection time determination circuit 34 and the output signal setting circuit 35 are shown in FIGS.
3 will be described in detail.

A characteristic line 43 shown by a solid line in FIG. 12 shows the relationship between the duty ratio of the PWM signal and the opening of the inflow / outflow ports 21 and 22 in an ideal case. In the characteristic diagram of FIG. 12, when the spool 24 moves from the neutral position in the direction of arrow E to open the inflow / outflow ports 21 and 22, the opening of the inflow / outflow ports 21 and 22 is set to a positive value. And the opening of the inflow / outflow ports 21 and 22 when the spool 24 moves from the neutral position in the direction of arrow F is represented as a negative value.

When the duty ratio of the PWM signal is 50
%, The spool 24 is connected to the inflow / outflow ports 21 and 22
In the neutral position to completely close off the
The opening of No. 22 is 0% as a percentage. When the duty ratio of the PWM signal is between 50% and (50 + Δ1)%, the spool 24 moves from the neutral position in the direction indicated by the arrow E within a certain dimension δ. %. Further, when the duty ratio of the PWM signal is between 50% and (50-Δ1)%, the spool 24 moves from the neutral position in the direction indicated by the arrow F within a certain dimension δ. Is kept at 0%.

When the duty ratio of the PWM signal is 100
%, The opening of the inflow / outflow ports 21 and 22 is 1
When the spool 24 moves to the maximum in the direction of the arrow E, the inflow / outflow ports 21 and 22 have the maximum opening so that the hydraulic cylinder 12 can be extended to the maximum. On the other hand, P
When the duty ratio of the WM signal is about 0%, the opening degree of the inflow / outflow ports 21 and 22 becomes -100%, and the spool 24 moves to the maximum in the direction of arrow F, so that the outflow / inflow ports 21 and 22 become hydraulic cylinders. 12 becomes the maximum opening degree so as to reduce the maximum.

However, in the actual spool valve 17, due to a manufacturing error of the spool 24 and a change with time of the spring 26, P
Even when the duty ratio of the WM signal is set to 50%, the spool 24 may not return to a fixed return position (neutral position). Also, the coil unit 2 in the electromagnetic actuator 27
7B generates heat over a long period of operation, and heat resistance may be generated due to heat conduction from the engine or the like. In this case, the spool valve 17 may not return to the return position of the spool valve 17, and the characteristic indicated by a dotted line in FIG. A shift Δ2 in the return position may occur as shown by a line 44.

For this reason, in this embodiment, an integral operation circuit 31 for performing an integral operation on the deviation e is provided, and outputs an operation value for compensating for the deviation Δ2 of the return position. by this,
The rod 12C can be brought to a substantial stop state in which micro-sliding is repeated in the vicinity of the original stop position, which is a target position, and the rod 12C becomes a substantial stop state in a state where the rod is shifted from the original stop position. Preventing.

Next, the operation of the integration operation circuit 31 and the detection time determination circuit 34 will be described in detail with reference to FIG. FIG. 13 shows the relationship between the detection value y, the proportional operation value u1, the integral operation value u2, the compensation operation value u3, and time. It is also assumed that the target value r has been changed to a constant value as indicated by a characteristic line 45 indicated by a dashed line in FIG. 13, and the control unit 28 outputs a PWM signal at a time interval of about 10 ms.

At this time, the coefficient Ki which is the gain of the integration operation
Is always set to K0 (Ki = K0) as a comparative example by a dotted line. First, immediately after the target value r changes stepwise from the initial value r0, the proportional operation value u1 is changed to the characteristic line 46.
And a large value corresponding to the deviation e (e = ry). Since the deviation e is a positive value (e> 0) as shown by the characteristic line 47 in the compensation operation value u3, the constant dimension .delta.
Is obtained as a constant Kb. Further, as shown by the characteristic line 48, the integral operation value u2 increases in accordance with the deviation e.

As a result, the spool 24 slides by a predetermined dimension δ in the direction indicated by the arrow E in accordance with the compensation operation value u3, for example, and also moves in the direction indicated by the arrow E in accordance with the proportional operation value u1 and the integral operation value u2. Sliding displacement. And rod 12C
Extends in the direction of the arrow A, and the oil chamber 12D of the hydraulic cylinder 12
Pressure oil is supplied from the hydraulic pump 1 to the inside, and the control shaft 10 rotates in the direction of arrow C, so that the phase difference Φ between the crankshaft 1 and the camshaft 4 changes.

Here, the detected value y is determined by the crank angle sensor 41
, And the second reference signal S2 from the cam position sensor 42, the detection value y changes with time in a stepwise manner as indicated by the characteristic line 49. The constant time .tau.1 until each of the reference signals S1 and S2 is output depends on the engine speed N. For example, the engine speed N
Is about 60 ms at 1000 rpm. On the other hand, the control unit 28
Since the PWM signal for driving the control signal 7 is output every 10 ms, for example, six calculations are performed between the time when the detection value y is calculated and the time when the detection value y is updated to the next detection value. At this time, one calculation performed immediately after the detection value y is calculated is performed based on the detection value y, whereas the other five calculations are performed based on the previous detection value y.

At this time, the proportional operation value u1 and the compensation operation value u
3 does not change with time as shown by the characteristic lines 46 and 47 during the fixed time τ1. On the other hand, the integration operation circuit 31 integrates the deviation e (e = ry) indicated by the characteristic line 50 with respect to time.
It has been confirmed that the integral operation value u2 increases as shown by the characteristic line 51 in FIG. 14 and tends to become an excessive value.

For this reason, the integral operation value u2 becomes a large value in a short time as shown by the characteristic line 48 in FIG. 13, and when a predetermined time τ2 elapses after the target value r is changed, the spool is calculated by the integral operation value u2. 24 is excessively displaced in the direction indicated by the arrow E, and an overshoot occurs in the hydraulic cylinder 12.

When the detected value y exceeds the target value r,
The proportional operation value u1 becomes a negative value corresponding to the deviation e, the compensation operation value u3 becomes a constant -Kb, and the integral operation value u2
Gradually decreases. In this way, the integral operation value u2 outputs a constant (constant value u20) corresponding to the deviation Δ2 of the return position, and the deviation e becomes almost zero (e = 0), so that the control shaft 10 The rotation angle is reached, and the vehicle is substantially stopped.

As described above, when the integral operation is performed even while the detected value y is not updated, when the engine speed N falls into a low rotation range, the integral operation value u2 determines the return position deviation Δ2. Exceeding the fixed value u20 for compensation, overshoot occurs in the hydraulic cylinder 12, and
The time required for the control shaft 10 to converge to the target value r tends to increase.

On the other hand, in this embodiment, the integration operation is performed only when the detection time is determined by the detection time determination circuit 34. At the non-detection time, the coefficient Ki serving as the gain of the integration operation is set to zero (Ki = 0). It is configured to be set. in this case,
The integral operation value u2 changes according to the time change of the deviation e as shown by the characteristic line 52 in FIG.

As a result, the integral operation value u2 gradually increases as shown by the characteristic line 53 in FIG. 13, and it is possible to prevent the integral operation value u2 from becoming excessively larger than the constant value u20 for compensating the return position deviation. Further, the proportional operation value u1 is a value corresponding to the deviation e as shown by the characteristic line 54, and the compensation operation value u3 is such that the deviation e is a positive value (e> 0) as shown by the characteristic line 55.
It is a constant Kb corresponding to the fixed dimension δ of the dead zone. As a result, the spool 24 is slid in the direction of arrow E, the rod 12C extends in the direction of arrow A, the control shaft 10 rotates in the direction of arrow C, and the detected value y is
As shown in FIG. 6, the value quickly converges to the target value r. Further, since the occurrence of overshoot can be prevented, the control shaft 10 can be brought into a substantially stopped state quickly without going too far in the direction of the arrow C beyond the target rotation angle. Can be operated with higher responsiveness.

Thus, according to the present embodiment, since the proportional operation circuit 30, the integral operation circuit 31, the compensation operation circuit 32 and the detection time judgment circuit 34 are provided in the control unit 28 for controlling the spool valve 17, the proportional operation circuit 30
The displacement e can be reduced by slidingly displacing the spool 24 in accordance with the deviation e, the deviation Δ2 of the return position generated in the spool valve 17 can be compensated by the integration operation circuit 31, and the dead zone of the spool valve 17 can be compensated by the compensation operation circuit 32. Compensation can be performed, and integral calculation can be performed based on the determination result of the detection time determination circuit 34.

Further, by performing the integral calculation only when the detection time determination circuit 34 determines that the detection time is reached, it is possible to prevent the integral calculation value u2 from becoming excessively large and to prevent the hydraulic cylinder 12 from overshooting. Thus, the operation of the hydraulic cylinder 12 can be optimized. Further, the control shaft 10 is set to the target value r by the hydraulic cylinder 12.
, The control shaft 10 can be brought into a substantially stopped state when the control shaft 10 reaches the target rotation angle, and the reliability and stability of the feedback control can be improved.

Then, the phase difference Φ generated between the crankshaft 1 and the camshaft 4 is controlled by the eccentric mechanism 7, so that the engine can be driven in an optimum state corresponding to the operating state of the engine, and an appropriate state can be obtained. Intake and exhaust are performed, and the operating performance of the engine can be improved.

Further, the operation detecting means is connected to the operation amount calculating circuit 4.
0, which is constituted by the crank angle sensor 41 and the cam position sensor 42, based on the reference signals S1 and S2 from the crank angle sensor 41 and the cam position sensor 42 provided for detecting the ignition point of the engine and the like. The actual rotation angle θ of the control shaft 10 can be calculated, and there is no need to separately provide a potentiometer or the like for detecting the actual rotation angle θ of the control shaft 10, so that manufacturing costs can be reduced. Since the crank angle sensor 41 and the cam position sensor 42 are connected to the detection time determination circuit 34, the detection time determination circuit 34 updates the detection value y based on the first and second reference signals S1 and S2. The detected detection time can be reliably determined.

In the above embodiment, the spool 24 is slid and displaced by the electromagnetic actuator 27 such as a proportional solenoid. However, the present invention is not limited to this, and a linear stepping motor is used in place of the proportional solenoid. You may.

In the above-described embodiment, the detection time determination circuit 34 detects the first reference signal S 1 from the crank angle sensor 41.
And the second reference signal S2 from the cam position sensor 42, the detection time is determined. However, the present invention is not limited to this, and the first reference signal S2 from the crank angle sensor 41 is not limited to this.
1 or the second reference signal S2 from the cam position sensor 42 may be used to determine the detection point in time.

Further, in the above-described embodiment, the crank angle sensor 41 and the cam position sensor 42 output the reference signals S1 and S2 once per one revolution of the engine. However, the present invention is not limited to this. For example, one of the engines
Each of the reference signals S1 and S2 may be output from the crank angle sensor 41 and the cam position sensor 42 two or more times per revolution.

[0101]

As described above in detail, according to the first aspect of the present invention, since the valve control means is provided with the integral operation means for performing the integral operation for the deviation, the deviation of the return position of the valve element caused in the control valve mechanism can be reduced. It is possible to reliably compensate. Also, the output value of the integration operation means can be interrupted only when the detection time is judged by the detection time judgment means, and the output of the operation value by the integration operation means can be interrupted at the non-detection time, and the control signal by the output signal setting means becomes excessive. Satisfactorily prevents overshoot and the like from occurring as well as corrects the deviation of the return position occurring in the control valve mechanism in a short time, and quickly brings the actuator to a substantial stop state at the target position. Can be.

In addition, the operation of the actuator can be optimized, and the reliability and stability of the feedback control can be improved. The actuator operates the rotation phase varying means to control the phase difference generated between the crankshaft and the camshaft. In addition, the engine can be driven in an optimal state corresponding to the operating state of the engine, and appropriate intake and exhaust are performed, so that the operating performance of the engine can be improved.

[0103] In addition, work movement detecting means of the crank position detector, because consisted cam position detector and the operation amount calculation circuit, first from the crank position detector is provided for detecting the ignition timing of the engine The operation amount of the rotation phase variable means can be calculated based on the reference signal and the second reference signal from the cam position detector, and there is no need to separately provide a potentiometer or the like for detecting the operation amount of the rotation phase variable means. In addition, the manufacturing cost can be reduced. Further, it is possible to reliably determine the detection time at which the detection value is updated based on the first and second detection signals.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing a crankshaft, a camshaft, and the like provided in an engine valve timing control device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a crankshaft, a disk holder, and the like in FIG. 1 together with a hydraulic cylinder.

FIG. 3 is a sectional view showing the eccentric disk together with a control shaft and the like as viewed from the direction of arrows III-III in FIG. 1;

FIG. 4 is a sectional view showing a hydraulic cylinder, a control valve device, and the like.

FIG. 5 is an enlarged cross-sectional view showing the relationship between a port and a land of the valve casing, as viewed from the direction indicated by arrows VV in FIG.

FIG. 6 is a control block diagram of a control unit and the like shown in FIG. 4;

FIG. 7 is an explanatory diagram showing a crankshaft, a camshaft, a crank angle sensor, a cam position sensor, and the like.

FIG. 8 is a characteristic diagram showing reference signals output from a crank angle sensor and a cam position sensor.

FIG. 9 is a flowchart showing a valve timing control process by a control unit.

FIG. 10 is a flowchart illustrating a detection value calculation process in FIG. 9;

FIG. 11 is a flowchart showing an integral gain adjustment process in FIG. 9;

FIG. 12 shows PWM output from the control unit.
FIG. 9 is a characteristic diagram illustrating a relationship between a signal duty ratio and an opening of an outflow / inflow port.

FIG. 13 is a characteristic diagram showing change characteristics of a detection value, a proportional operation value, an integral operation value, and a compensation operation value when the control shaft is rotated.

FIG. 14 is a characteristic diagram showing a relationship between a deviation and an integral operation value.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 crankshaft 4 camshaft 7 eccentric mechanism (variable rotation phase means) 12 hydraulic cylinder (actuator) 14 tank 15 hydraulic pump 16 control valve device (control valve mechanism) 24 spool (valve element) 27 electromagnetic actuator 28 control unit (valve control) 29) Deviation operation circuit (deviation operation means) 30 Proportional operation circuit (proportional operation means) 31 Integral operation circuit (Integration operation means) 32 Compensation operation circuit (Compensation operation means) 34 Detection time judgment circuit (Detection time judgment means) 35 Output signal setting circuit (output signal setting means) 39 Target value setting circuit (target value setting means) 40 Working amount calculation circuit 41 Crank angle sensor (Crank position detector) 42 Cam position sensor (Cam position detector)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-299813 (JP, A) JP-A-5-66801 (JP, A) JP-A-7-332118 (JP, A) JP-A-7- 83080 (JP, A) JP-A-7-26992 (JP, A) JP-A-7-269380 (JP, A) JP-A-7-11980 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 13/02 F02D 41/00-45/00 395

Claims (1)

(57) [Claims] 1. A method for controlling a valve timing of an internal combustion engine to variably control a rotation phase of a crankshaft and a camshaft of the internal combustion engine. Therefore, an actuator that is driven and controlled by the hydraulic pressure supplied and discharged from the hydraulic pressure source, and is disposed between the actuator and the hydraulic pressure source, and always keeps the valve body at a neutral position with a dead zone having a fixed width. A control valve mechanism for slidingly displacing the valve body from a neutral position when supplying and discharging hydraulic pressure to and from the actuator from the hydraulic pressure source, and a valve body of the control valve mechanism according to a control signal for operating the actuator. A valve timing control device for the internal combustion engine, the valve timing control device comprising: As is changed in accordance with the state, the target value setting means for setting a target value for operating the rotational phase varying means I and the crankshaft rotational phase constant rotational phase
The first base output from the crank position detector when the
If the reference signal and the rotation phase of the camshaft are
The second reference signal output from the cam position detector when the
And the detected value of the amount of operation of the rotation phase variable means based on
Every time the first and second reference signals are updated.
Operation detection means comprising an operation amount calculation circuit for updating the detection value; deviation calculation means for calculating a deviation between a target value by the target value setting means and a detection value by the operation detection means; Proportional operation means for performing a proportional operation on the deviation of the integral operation means for performing an integral operation on the deviation from the deviation operation means; and performing dead zone compensation of the control valve mechanism. Compensation operation means for compensating for the dead zone; detection time judgment means for judging when the value detected by the operation detection means is updated as a detection time, and otherwise as a non-detection time; When it is determined by the determination means that the time is the detection time, the control valve mechanism is determined based on respective calculation values of the proportional calculation means, the integration calculation means and the compensation calculation means. An internal combustion engine comprising: a control signal to be output; and output signal setting means for setting a control signal based on the respective calculated values of the proportional calculation means and the compensation calculation means when it is determined that the control signal has not been detected. Valve timing control device.