JP3616736B2 - Sliding mode controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sliding mode control, for example, a sliding mode control device used for feedback control of a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine to a target value.
[0002]
[Prior art]
Japanese Laid-Open Patent Publication No. 10-141022 discloses a valve timing control device having such a configuration that continuously changes the intake / exhaust valve opening / closing timing by changing the rotational phase of the camshaft relative to the crankshaft. There is such a vane type valve timing control device.
[0003]
In this case, a recess is formed on the inner peripheral surface of a cylindrical housing fixed to the cam sprocket, while a vane of a impeller fixed to the camshaft is accommodated in the recess, The camshaft can be rotated relative to the cam sprocket within a range in which the wing can move.
[0004]
And the said wing | blade part hold | maintains the said wing | blade part in the intermediate position of the said recessed part by supplying and discharging oil relatively with respect to a pair of hydraulic chamber formed by dividing the said recessed part into the front and back of a rotation direction. The rotation phase is continuously variable. When the hydraulic pressure in the pair of hydraulic chambers is adjusted to the hydraulic pressure at which the target rotation phase is obtained, the hydraulic passage is closed by the control valve. It is configured to stop supply and discharge.
[0005]
[Problems to be solved by the invention]
By the way, as a control method of the camshaft rotation phase, PID control or the like is generally adopted. In this case, the control amount is a deviation (error) between the actual angle of the camshaft to be controlled and the target angle. Only) is calculated as a single variable.
[0006]
However, in order to execute the PID control with high responsiveness, it is desirable to variably set the feedback gain because the viscosity of the oil changes according to the oil temperature and oil pressure. However, matching of the settings is not easy.
[0007]
Also, in hydraulic control, there is a large operating dead zone of the switching valve (spool valve) that switches between oil supply and discharge. In order to overcome this dead zone, dither control is performed by adding a dither component separately from PID. However, it is necessary to finely set the additional judgment for dither, and it becomes complicated control, which takes up the capacity of ROM and RAM, and in order to secure the control accuracy by reducing the variation of the dead zone width for each part In this case, the machining accuracy of the parts had to be increased, and the machining cost was increased.
[0008]
For this reason, the transition from general PID control to sliding mode control in which the influence of disturbance is small is being studied.
The present invention has been made in view of such a situation, and an object of the present invention is to provide an apparatus capable of performing higher-precision control in an apparatus that performs feedback control by sliding mode control.
[0009]
[Means for Solving the Problems]
For this reason, the invention according to claim 1
In a sliding mode control device that calculates a control amount by sliding mode control and performs feedback control of a control target to a target value,
The control amount calculated by the sliding mode control is corrected by dither control.Control
And while calculating the switching function S in the said sliding mode control by the following arithmetic expression,
The condition for adding the correction amount by the dither control is set from the following conditions based on the switching function S.
Formula for the switching function S;
S = γ × PERR + d (PERR) / dt
γ: inclination
PERR: Deviation between the target value to be controlled and the actual value
d (PERR) / dt: differential value of the above deviation
Conditions for adding a correction amount by dither control;
S · ΔS ≧ 0 where ΔS is the amount of change in S
[0010]
According to the invention of claim 1,
By sliding mode control, it is possible to perform highly robust control with less influence of disturbance compared to feedback control by normal PID control, etc., and at the same time, more accurate control can be performed by correcting by dither control. Can be done.
[0012]
Also,Switching function in sliding mode controlSCan be given as a function of the deviation between the target value of the control target and the actual value, a control amount (nonlinear term) corresponding to the deviation can be given, so that the dead zone can be overcome. Control amount is automatically calculated, and feedback control with good responsiveness can be performed.
[0013]
Further, by performing correction by dither control, the nonlinear term in the sliding mode control is finely adjusted, and high-accuracy control that secures optimum responsiveness can be performed. In other words, since the dither control only needs to have an adjustment function that supplements the sliding mode control, the control including the additional determination conditions is simplified compared to the dither control added in the conventional PID control. RAM capacity can also be saved.
[0015]
further,The switching functionSIs calculated as a function of the deviation, the correction amount by the dither control can be added only when necessary according to the deviation. In addition, a switching function calculated for sliding mode control may be used, and the calculation load for determination is reduced.
[0016]
AndAs the switching coefficient S, in addition to the deviation PERR between the target value to be controlled and the actual value, the differential value d (PERR) / dt of the deviation is given, so that the sliding mode along the switching line is smoother. It can be.
[0017]
Also,Claim 2The invention according to
The switching function S is calculated by the following equation.
S = γ × PERR + d (NOW) / dt
γ: inclination
PERR: Deviation between the target value to be controlled and the actual value
d (NOW) / dt: Actual speed of the controlled object
SaidClaim 1Even if the actual speed, which is the differential value of the position to be controlled, is given instead of the differential value d (PERR) / dt of the deviation PERR amount at, the sliding mode along the switching line is similarly smoothed. be able to.
[0018]
Also,Claim 3The invention according to
The control amount U in the sliding mode control is calculated by the following equation.
[0019]
U = c * PERR + d * {d (NOW) / dt} -K [S / (| S | + δ)]
d (NOW) / dt: Speed of change of control target
c, d: constant
δ: Chattering prevention coefficient
Claim 3According to the invention according to
The linear term control amount UL represented by c × PERR + d × {d (NOW) / dt] has a role of adjusting the speed at which the state of the control system approaches the switching line (S = 0), and −K [ Nonlinear term control amount U expressed by (S / (| S | + δ)]_NLHas a role of generating a sliding mode along the switching line.
[0021]
In addition, by setting the conditions for adding the correction amount by the dither control from the following conditions based on the switching function S, the following effects can be obtained in common with the inventions according to all the claims.
S · ΔS ≧ 0 where ΔS is the amount of change in S
For example,When the target position (target value) of the controlled object changes from the steady state where the switching valve or the like is in the dead zone, the actual position of the controlled object does not change until it is out of the dead zone. The absolute value (same below) continues to increase. That is, S · ΔS ≧ 0. During this time, the dither is added unconditionally so that the control object quickly moves out of the dead zone and starts operating quickly.
[0024]
Further, the setting of the additional condition for the dither as described above is promptly performed while the control state is set to the switching line (S = 0) and the overshoot is suppressed together with the linear term (for example, set in proportion to the deviation) in the sliding mode control. It also has a function of starting a sliding mode on the switching line.
[0025]
Also,Claim 4The invention according to
The control object is a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine, and the open / close timing of intake and exhaust valves is continuously variably controlled by feedback controlling the rotational phase to a target value. To do.
[0026]
Claim 4According to the present invention, in the configuration in which the valve timing is continuously changed by changing the rotational phase of the camshaft with respect to the crankshaft, the valve timing (substantial control) is combined with sliding mode control and dither control. The target can be feedback controlled with high accuracy.
[0027]
Also,Claim 5The invention according to
The rotational phase of the camshaft is controlled by selectively controlling the supply and discharge of oil to and from a hydraulic actuator that is hydraulically controlled by a switching valve.
[0028]
Claim 5According to the invention according to
By selectively controlling the supply and discharge of oil to and from the hydraulic actuator, the drive direction of the hydraulic actuator can be switched by adjusting the amount of oil to the hydraulic chamber, and the camshaft rotation phase can be continuously controlled. Are variably controlled.
[0029]
And, by applying sliding control to the hydraulic control mechanism, it is difficult to be affected by disturbances such as the dead zone of the switching valve, disturbances such as oil temperature and hydraulic pressure, and it is possible to perform highly robust control and process parts The accuracy can be lowered, the processing cost can be reduced, and by using the dither control together, fine adjustment can be made to the dead zone, and the control accuracy can be increased as much as possible.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
1 to 6 show a mechanism portion of a valve timing control device for an internal combustion engine that performs feedback control using sliding mode control together with dither control in this embodiment, and is applied to the intake valve side. Show.
[0031]
The valve timing control device shown in the figure is provided so as to be rotatable relative to the cam sprocket 1 (timing sprocket) that is rotationally driven via a timing chain by an engine crankshaft (not shown). Camshaft 2, rotating member 3 fixed to the end of camshaft 2 and rotatably accommodated in cam sprocket 1, and hydraulic circuit for rotating the rotating member 3 relative to cam sprocket 1 4 and a lock mechanism 10 that selectively locks the relative rotational position of the cam sprocket 1 and the rotating member 3 at a predetermined position.
[0032]
The cam sprocket 1 includes a rotating portion 5 having a tooth portion 5a meshing with a timing chain (or timing belt) on the outer periphery, and a housing 6 disposed in front of the rotating portion 5 and rotatably accommodating the rotating member 3. A disc-shaped front cover 7 serving as a lid for closing the front end opening of the housing 6, and a substantially disc-shaped rear cover disposed between the housing 6 and the rotating portion 5 to close the rear end of the housing 6. 8, and the rotating portion 5, the housing 6, the front cover 7, and the rear cover 8 are integrally coupled from the axial direction by four small-diameter bolts 9.
[0033]
The rotating portion 5 has a substantially annular shape, and has four female screw holes 5b through which the small-diameter bolts 9 are screwed at equal circumferential positions of about 90 ° in the circumferential direction. A step-diameter fitting hole 11 into which a passage-forming sleeve 25 described later is fitted is formed through. Further, a disc-shaped fitting groove 12 into which the rear cover 8 is fitted is formed on the front end surface.
[0034]
The housing 6 has a cylindrical shape in which both front and rear ends are formed with openings, and four partition walls 13 project from the circumferential position of the inner peripheral surface at 90 °. The partition wall 13 has a trapezoidal shape in cross section, is provided along the axial direction of the housing 6, and both end edges are flush with the both end edges of the housing 6. Four bolt insertion holes 14 through which the small-diameter bolts 9 are inserted are formed penetrating in the axial direction. Further, a U-shaped seal member 15 and a leaf spring 16 that presses the seal member 15 inward are fitted into a holding groove 13a that is cut out along the axial direction at the center position of the inner end face of each partition wall 13. Is retained.
[0035]
Further, the front cover 7 has a relatively large-diameter bolt insertion hole 17 at the center, and four bolt holes 18 at positions corresponding to the bolt insertion holes 14 of the housing 6. ing.
[0036]
The rear cover 8 has a disc portion 8a fitted and held in the fitting groove 12 of the rotating member 5 on the rear end face, and a small-diameter annular portion 25a of the sleeve 25 is fitted in the center. A fitting hole 8c is formed, and four bolt holes 19 are similarly formed at positions corresponding to the bolt insertion holes 14.
[0037]
The camshaft 2 is rotatably supported at the upper end portion of the cylinder head 22 via a cam bearing 23, and a cam (not shown) for opening the intake valve via a valve lifter is integrated at a predetermined position on the outer peripheral surface. In addition, a flange portion 24 is integrally provided at the front end portion.
[0038]
The rotating member 3 is fixed to the front end portion of the camshaft 2 by a fixing bolt 26 inserted from the axial direction through the sleeve 25 whose front and rear portions are fitted in the flange portion 24 and the fitting hole 11, respectively. An annular base 27 having a bolt insertion hole 27a through which the fixing bolt 26 is inserted, and four vanes 28a, 28b, 28c, 28d provided integrally at 90 ° in the circumferential direction of the outer peripheral surface of the base 27, It has.
[0039]
The first to fourth vanes 28a to 28d each have a substantially inverted trapezoidal cross section, and are disposed in the recesses between the partition walls 13, and the recesses are separated in the front and rear in the rotation direction. An advance side hydraulic chamber 32 and a retard side hydraulic chamber 33 are formed between both sides and both side surfaces of each partition wall 13. In addition, a U-shaped seal member 30 slidably contacting the inner peripheral surface 6a of the housing 6 and the seal member 30 are pressed outwardly into a holding groove 29 that is axially cut out in the center of the outer peripheral surface of each vane 28a to 28d. The leaf springs 31 are fitted and held.
[0040]
The lock mechanism 10 is formed through an engagement groove 20 formed at a predetermined position on the outer peripheral side of the fitting groove 12 of the rotating portion 5 and a predetermined position of the rear cover 8 corresponding to the engagement groove 20. An engagement hole 21 whose inner peripheral surface is tapered, a sliding hole 35 formed through the substantially central position of the one vane 28 corresponding to the engagement hole 21 along the internal axis direction, and the one A lock pin 34 slidably provided in the sliding hole 35 of the vane 28, a coil spring 39 that is a spring member elastically mounted on the rear end side of the lock pin 34, and the lock pin 34 and the sliding hole 35 is formed with a pressure receiving chamber 40 formed between them.
[0041]
The lock pin 34 includes a middle-side main body 34a on the center side, an engaging portion 34b formed in a substantially tapered shape on the front end side of the main body 34a, and a large step formed on the rear end side of the main body 34a. The engaging hole 21 is formed by a spring force of the coil spring 39 elastically mounted between the bottom surface of the inner concave groove 34d of the stopper portion 34c and the inner end surface of the front cover 7. And the hydraulic pressure in the pressure receiving chamber 40 formed between the outer peripheral surface between the main body 34a and the stopper portion 34c and the inner peripheral surface of the sliding hole 35. It slides in the direction of coming out of the engagement hole 21. The pressure receiving chamber 40 communicates with the retard angle side hydraulic chamber 33 through a through hole 36 formed in a side portion of the vane 28. Further, the engaging portion 34 b of the lock pin 34 engages with the engaging hole 21 in the rotation position on the maximum retard angle side of the rotating member 3.
[0042]
The hydraulic circuit 4 includes two systems, a first hydraulic passage 41 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 32 and a second hydraulic passage 42 that supplies and discharges hydraulic pressure to the retard side hydraulic chamber 33. The hydraulic passages 41 and 42 are connected to a supply passage 43 and a drain passage 44 through passage-switching electromagnetic switching valves 45, respectively. The supply passage 43 is provided with an oil pump 47 that pumps the oil in the oil pan 46, while the downstream end of the drain passage 44 communicates with the oil pan 46.
[0043]
The first hydraulic passage 41 is branched and formed in the head portion 26a from the cylinder head 22 through the first passage portion 41a formed in the axial center of the camshaft 2 and the axial direction in the fixing bolt 26. A first oil passage 41b that communicates with the first passage portion 41a, a small-diameter outer peripheral surface of the head portion 26a, and an inner peripheral surface of the bolt insertion hole 27a that is provided in the base portion 27 of the rotating member 3 are the first. An oil chamber 41c that communicates with the oil passage 41b, and four branch passages 41d that are formed substantially radially in the base 27 of the rotating member 3 and communicate with the oil chamber 41c and each advance-side hydraulic chamber 32 are configured. Yes.
[0044]
On the other hand, the second hydraulic passage 42 is formed into a second passage portion 42 a formed in the cylinder head 22 and on one side of the camshaft 2, and is bent into a substantially L shape inside the sleeve 25. A second oil passage 42b communicating with the passage portion 42a, four oil passage grooves 42c formed at the outer peripheral side edge of the fitting hole 11 of the rotating member 5 and communicating with the second oil passage 42b, and the periphery of the rear cover 8. The four oil holes 42d are formed at positions of about 90 ° in the direction and communicate with the respective oil passage grooves 42c and the retard-side hydraulic chamber 33.
[0045]
The electromagnetic switching valve 45 is configured such that an internal spool valve body switches and controls each of the hydraulic passages 41 and 42, the supply passage 43, and the drain passages 44a and 44b, and a control signal from the controller 48. It is designed to be switched by.
[0046]
Specifically, as shown in FIGS. 4 to 6, a cylindrical valve body 51 inserted and fixed in the holding hole 50 of the cylinder block 49 and a valve hole 52 in the valve body 51 are slidable. The spool valve body 53 is provided to switch the flow path, and a proportional solenoid type electromagnetic actuator 54 that operates the spool valve body 53.
[0047]
The valve body 51 is formed with a supply port 55 penetrating the downstream end of the supply passage 43 and the valve hole 52 at a substantially central position of the peripheral wall, and the first and the second on both sides of the supply port 55. A first port 56 and a second port 57 that communicate with the other end of the second hydraulic passages 41 and 42 and the valve hole 52 are formed penetratingly. Further, third and fourth ports 58 and 59 are formed through both ends of the peripheral wall so as to communicate the drain passages 44a and 44b with the valve hole 52.
[0048]
The spool valve body 53 has a substantially cylindrical first valve portion 60 that opens and closes the supply port 55 at the center of the small diameter shaft portion, and opens and closes the third and fourth ports 58 and 59 at both ends. It has substantially cylindrical second and third valve portions 61 and 62. The spool valve body 53 is a conical valve spring 63 elastically mounted between an umbrella portion 53b provided at one end edge of the support shaft 53a on the front end side and a spring seat 51a provided on the inner peripheral wall of the front end side of the valve hole 52. Therefore, the supply valve 55 and the second hydraulic passage 42 are urged in the right direction in FIG.
[0049]
The electromagnetic actuator 54 includes a core 64, a moving plunger 65, a coil 66, a connector 67, and the like, and a driving rod 65 a that presses the umbrella portion 53 b of the spool valve body 53 is fixed to the tip of the moving plunger 65.
[0050]
The controller 48 detects the current operating state (load, rotation) based on signals from the rotation sensor 101 that detects the engine rotation speed and the air flow meter 102 that detects the intake air amount, and from the crank angle sensor 103 and the cam sensor 104. The relative rotation position of the cam sprocket 1 and the camshaft 2, that is, the rotational phase of the camshaft 2 with respect to the crankshaft is detected by the above signal.
[0051]
The controller 48 controls the energization amount for the electromagnetic actuator 54 based on a duty control signal.
For example, when a control signal (OFF signal) with a duty ratio of 0% is output from the controller 48 to the electromagnetic actuator 54, the spool valve body 53 moves to the position shown in FIG. . As a result, the first valve portion 60 opens the open end 55a of the supply port 55 to communicate with the second port 57, and at the same time, the second valve portion 61 opens the open end of the third port 58, and the fourth The valve part 62 closes the fourth port 59. Therefore, the hydraulic oil pressure-fed from the oil pump 47 is supplied to the retarded hydraulic chamber 33 through the supply port 55, the valve hole 52, the second port 57, and the second hydraulic passage 42, and at the advanced side. The hydraulic oil in the hydraulic chamber 32 is discharged from the first drain passage 44a into the oil pan 46 through the first hydraulic passage 41, the first port 56, the valve hole 52, and the third port 58.
[0052]
Therefore, the internal pressure of the retard side hydraulic chamber 33 is high and the internal pressure of the advance side hydraulic chamber 32 is low, and the rotating member 3 rotates in one direction at the maximum via the vanes 28a to 28b. As a result, the cam sprocket 1 and the camshaft 2 rotate relative to one side to change the phase. As a result, the opening timing of the intake valve is delayed and the overlap with the exhaust valve is reduced.
[0053]
On the other hand, when a control signal (ON signal) with a duty ratio of 100% is output from the controller 48 to the electromagnetic actuator 54, the spool valve body 53 is maximally leftward against the spring force of the valve spring 63 as shown in FIG. At the same time as the third valve portion 61 closes the third port 58 by sliding, the fourth valve portion 62 opens the fourth port 59, and the first valve portion 60 includes the supply port 55 and the first port 56. To communicate with. Therefore, the hydraulic oil is supplied into the advance side hydraulic chamber 32 through the supply port 55, the first port 56, and the first hydraulic passage 41, and the hydraulic oil in the retard side hydraulic chamber 33 is second. The oil is discharged to the oil pan 46 through the hydraulic passage 42, the second port 57, the fourth port 59, and the second drain passage 44b, and the retard side hydraulic chamber 33 becomes low pressure.
[0054]
For this reason, the rotating member 3 rotates to the maximum in the other direction via the vanes 28a to 28d, whereby the cam sprocket 1 and the camshaft 2 are relatively rotated to the other side and the phase is changed. The opening timing of the intake valve is advanced (advanced), and the overlap with the exhaust valve is increased.
[0055]
The controller 48 has a position in which the first valve portion 60 closes the supply port 55, the third valve portion 61 closes the third port 58, and the fourth valve portion 62 closes the fourth port 59. The relative duty position (rotation phase) between the cam sprocket 1 and the camshaft 2 detected based on signals from the crank angle sensor 103 and the cam sensor 104, and the operation state A feedback correction amount UFBDTY for matching the target value (target advance angle value) of the relative rotation position (rotation phase) set in accordance with is set, and the base duty ratio BASEDTY and the feedback correction amount UFBDTY are added. The result is the final duty ratio VTCDTY, and the control signal for the duty ratio VTCDTY is sent to the electromagnetic actuator. It is to be output to the data 54. The base duty ratio BASEDTY is a substantially median value of the duty ratio range in which the supply port 55, the third port 58, and the fourth port 59 are all closed and no oil is supplied or discharged in any of the hydraulic chambers 32 and 33. (For example, 50%).
[0056]
That is, when it is necessary to change the relative rotation position (rotation phase) in the retarding direction, the duty ratio is reduced by the feedback correction amount UFBDTY, and the hydraulic oil pumped from the oil pump 47 is retarded. While being supplied to the hydraulic chamber 33, the hydraulic oil in the advance side hydraulic chamber 32 is discharged into the oil pan 46. Conversely, the relative rotation position (rotation phase) is changed in the advance direction. When it is necessary to increase the duty ratio, the duty ratio is increased by the feedback correction UFBDTY, the hydraulic oil is supplied into the advance hydraulic chamber 32, and the hydraulic oil in the retard hydraulic chamber 33 is supplied to the oil pan 46. Will be discharged. When the relative rotation position (rotation phase) is maintained in the current state, the absolute value of the feedback correction amount UFBDTY is reduced, and the supply port is controlled to return to a duty ratio near the base duty ratio. The internal pressures of the hydraulic chambers 32 and 33 are controlled by closing the 55, the third port 58, and the fourth port 59 (stopping the supply and discharge of hydraulic pressure).
[0057]
Here, the feedback correction amount UFBDTY is calculated as follows by using sliding mode control and dither control together. In the following description, the detected relative rotation position (rotation phase) between the cam sprocket 1 and the camshaft 2 will be described as the actual angle of the valve timing control device (VTC), and its target value will be described as the VTC target angle.
[0058]
FIG. 7 is a block diagram showing a state of duty control of the electromagnetic actuator 54 by the controller 48 to which the sliding mode control and the dither control designed as described above are applied.
[0059]
First, in the sliding mode control unit, the linear term calculation unit calculates a deviation PERR between the target angle VTCTRG of the VTC and the actual angle VTCNOW, and a proportional control amount U obtained by multiplying the deviation PERR by a P-component gain c._PAnd the speed control amount U obtained by multiplying the differential value (d (VTCNOW) / dt) of the actual angle VTCNOW by the speed gain d._N(= D × d (VTCNOW) / dt) is added to the linear term control amount U_LIs calculated.
[0060]
The nonlinear term calculation unit calculates a switching function S by adding a value obtained by multiplying the deviation PERR by the slope γ and a differential value d (PERR) / dt of the deviation PERR, and uses the switching function S. Nonlinear term control amount U as smoothing function −kS / (| S | + δ)_NLIs calculated.
[0061]
In the smoothing function, k is a nonlinear term gain, and δ is a chattering prevention coefficient.
The linear term control amount U_LHas a role of adjusting the speed at which the state of the control system (VTC) is brought close to the switching line (S = 0), and the nonlinear term control amount U_NLHas a role of generating a sliding mode along the switching line. As a result, when the system state is shifted from the initial state to the switching line (S = 0) on the phase plane and the state is on the switching line (S = 0), the system line is restrained on the switching line (S = 0). The origin (target value) is reached while sliding (see FIG. 8).
[0062]
And the linear term control amount U_LAnd the nonlinear term control amount U_NLAre added to calculate the total control amount UDTY in the sliding mode control.
On the other hand, in the dither control unit, the addition determination unit determines whether to add a dither amount (correction amount) based on the switching function S. Specifically, the dither amount D0 is added when S × ΔS ≧ 0 or | S | ≧ S0 (> 0), and the addition of the dither amount D0 is stopped at other times, that is, when | S | <S0. To do. That is, D0 = 0. After the addition determination is performed in this manner, the dither amount D0 is output from the output unit.
[0063]
That is, when the target angle of the VTC changes from the state in which the switching valve is in the dead zone, the actual angle does not change until the switching valve is removed from the dead zone, as shown in FIG. The absolute value (same below) continues to increase and S · ΔS ≧ 0. Therefore, during this time, the dither is unconditionally added so that the switching valve is quickly removed from the dead zone and the VTC starts to operate quickly.
[0064]
When the switching valve moves out of the dead zone and the VTC starts to operate, the switching function S begins to decrease with the deviation. However, until the target angle is approached to some extent, that is, when | S | ≧ S0 is satisfied, By adding the minute, it quickly approaches the target angle to ensure high responsiveness.
[0065]
When the VTC approaches the target angle and | S | <S0, by stopping the addition of the dither, it is possible to suppress overshoot due to an excessive control amount and quickly converge to the target angle. .
[0066]
When the deviation PERR (target angle−actual angle) is a positive value, the dither amount D0 is set to a value in a direction that increases the actual angle (for example, a positive value), and when the deviation is a negative value, The dither amount D0 is set to a value (for example, a negative value) in a direction that increases the actual angle.
[0067]
In addition, the value of the dither amount D0 is set to a value large enough to get out of the dead band in the case of PID control, but in the present invention, the nonlinear term in the sliding mode control largely performs the function of the dither control. Therefore, the dither amount D0 may be set to a value that gives a fine adjustment function. However, the dither amount D0 can be set to be sufficiently large, and the required change due to the oil temperature and hydraulic pressure can be adjusted by the nonlinear term of the sliding mode control.
[0068]
Then, the dither amount D0 in the dither control (D0 = 0 at the time of addition stop) is added to the total control amount UDTY in the sliding mode control to calculate the feedback correction amount UFBDTY, and the feedback correction amount UFBDTY is calculated. The base duty ratio BASEDTY corresponding to the dead zone neutral position is added and the addition result is output as the final duty ratio VTCDTY.
[0069]
In this way, basically, the sliding mode control makes it difficult to be affected by disturbances such as the dead zone of the switching valve, disturbances such as oil temperature and hydraulic pressure, and the control can be performed with high robustness, and the machining accuracy of the parts can be increased. By reducing the machining cost and performing correction by dither control, the adjustment function acts to improve the control performance such as obtaining an optimum response.
[0070]
In addition, the burden of dither control is reduced compared to the case where the conventional PID control is used together, and the additional determination conditions for the dither are also simpler than the complicated additional determination including the conventional oil temperature, hydraulic pressure, etc. Judgment conditions are sufficient. In particular, in the addition determination of the dither based on the switching function S calculated as a function of the deviation PERR as in the present embodiment, the dither can be added only when necessary according to the deviation. The diversion of S also reduces the calculation load for determination. Further, the setting of the additional condition for the dither based on the switching function S as described above is performed by overshooting the control state on the switching line (S = 0) together with a linear term (for example, set in proportion to the deviation) in the sliding mode control. It also has a function of quickly approaching while suppressing and starting a sliding mode on the switching line. In addition to this, the addition determination of the dither may be determined based on the deviation PERR, for example, the addition of the dither when PERR · ΔPERR ≧ 0 or | PERR |> PERR0 (> 0). .
[0071]
In this way, the entire control including the sliding mode control is simplified, and the capacity of the ROM and RAM can be saved.
In the above embodiment, the one applied to the hydraulic vane type VTC is shown. However, the present invention can be applied not only to the hydraulic control type VTC but also to an electromagnetic type VTC, and the present invention is applied to the VTC. Without being limited thereto, the present invention can be widely applied to apparatuses that basically calculate a control amount by sliding mode control and perform feedback control of a control target to a target value.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a valve timing control mechanism in an embodiment.
2 is a cross-sectional view taken along the line BB in FIG.
FIG. 3 is an exploded perspective view of the valve timing control mechanism.
FIG. 4 is a longitudinal sectional view showing an electromagnetic switching valve in the valve timing control mechanism.
FIG. 5 is a longitudinal sectional view showing an electromagnetic switching valve in the valve timing control mechanism.
FIG. 6 is a longitudinal sectional view showing an electromagnetic switching valve in the valve timing control mechanism.
FIG. 7 is a control block diagram of the valve timing control mechanism.
FIG. 8 is a time chart showing how the valve timing control mechanism converges to a target angle during sliding mode control.
FIG. 9 is a diagram showing a change in the switching function S during the control of the valve timing control mechanism and whether or not dither is added due to the change.
[Explanation of symbols]
2 ... Camshaft
4 ... Hydraulic circuit
32 ... Advance side hydraulic chamber
33 ... retarded-side hydraulic chamber
45 ... Electromagnetic switching valve
47 ... Oil pump
53 ... Spool valve body
101 ... Rotation sensor
102 ... Air flow meter
103 ... Crank angle sensor
104: Cam sensor

Claims (5)

In a sliding mode control device that calculates a control amount by sliding mode control and performs feedback control of a control target to a target value,
The control amount calculated by the sliding mode control is corrected and controlled by dither control ,
And while calculating the switching function S in the said sliding mode control by the following arithmetic expression,
A sliding mode control apparatus, wherein a condition for adding a correction amount by the dither control is set from the following condition based on the switching function S.
Formula for the switching function S;
S = γ × PERR + d (PERR) / dt
γ: inclination
PERR: Deviation between the target value to be controlled and the actual value
d (PERR) / dt: differential value of the above deviation
Conditions for adding a correction amount by dither control;
S · ΔS ≧ 0 where ΔS is the amount of change in S In a sliding mode control device that calculates a control amount by sliding mode control and performs feedback control of a control target to a target value,
The control amount calculated by the sliding mode control is corrected and controlled by dither control,
And while calculating the switching function S in the said sliding mode control by the following arithmetic expression,
A sliding mode control apparatus, wherein a condition for adding a correction amount by the dither control is set based on the switching function S based on the following condition.
Formula for the switching function S;
S = γ × PERR + d (NOW) / dt
γ: inclination
PERR: Deviation between the target value to be controlled and the actual value
d (NOW) / dt: Speed of change of control target
Conditions for adding a correction amount by dither control;
S · ΔS ≧ 0 where ΔS is the amount of change in S The sliding mode control device according to claim 1 or 2, wherein the control amount U in the sliding mode control is calculated by the following equation.
U = c * PERR + d * {d (NOW) / dt} -K [S / (| S | + δ)]
d (NOW) / dt: speed of change c, d: constant δ: chattering prevention coefficient The control object is a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine, and the open / close timing of intake and exhaust valves is continuously variably controlled by feedback-controlling the rotational phase to a target value. The sliding mode control device according to any one of claims 1 to 3 . 5. The sliding mode control device according to claim 4 , wherein the rotational phase of the camshaft is controlled by selectively controlling supply / discharge of oil to / from a hydraulic actuator that is hydraulically controlled by a switching valve.

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