JP2009150316A - Variable valve train, its control device, and internal combustion engine equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve train control device for performing highly accurate and inexpensive feedback control of a variable valve train even when the operating conditions of an internal combustion engine or the operating conditions including the operating speed of the variable valve train are changed, and also to provide the variable valve train and the internal combustion engine equipped therewith. <P>SOLUTION: The control device comprises: a state quantity detecting means 602 for detecting the state quantity of the variable valve train 113 and outputting a signal corresponding to the detected state quantity of the variable valve train, as a state quantity detected value; a state quantity estimating means 603 for estimating the state quantity of the variable valve train using a dynamic model for the variable valve train and outputting a signal corresponding to the estimated state quantity of the variable valve train, as a state quantity estimated value; and a coefficient correcting means 1003 for correcting the model coefficient of the dynamic model in accordance with the state quantity detected value output by the state quantity detecting means and the state quantity estimated value outputted by the state quantity estimating means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism provided in an intake valve and an exhaust valve of an internal combustion engine (engine), and opening / closing characteristics (open / close timing, lift amount, etc.) of the intake valve and the exhaust valve via the variable valve mechanism. The present invention relates to a control device for a variable valve mechanism that controls the engine, and the variable valve mechanism and an internal combustion engine equipped with the control device.

  Conventionally, a control device for a variable valve mechanism of an internal combustion engine includes a crank angle sensor that outputs a crank angle signal at a reference rotation position of the crankshaft, and a cam sensor that outputs a cam signal at a reference rotation position of the camshaft, A device that detects the rotational phase of the camshaft relative to the crankshaft based on the deviation angle of each reference rotational position is known.

  The control device for a variable valve mechanism according to this conventional example calculates the rotation phase of the camshaft with respect to the crankshaft based on a signal detected for each reference rotation angle, and changes the variable valve operation based on the calculated rotation phase. Feedback control of the valve timing of the mechanism. In general, this feedback control is executed every minute time, but detection of the rotation phase is executed for each reference rotation angle. Therefore, when the engine speed is low, the detection cycle of the rotation phase is lower than the control cycle of the feedback control. In some cases, the rotational phase becomes longer and the rotational phase cannot be detected with sufficient frequency for control. In such a case, the control system recognizes the past rotational phase value as the actual rotational phase value and executes feedback control. Therefore, feedback control based on an incorrect value is easily performed, and variable control is performed. There is a problem that the controllability of the valve mechanism is deteriorated.

  In order to solve the problems of the prior art, the applicant of the present application previously attached a rotating body having an outer peripheral shape whose distance from the rotation center gradually changes in the circumferential direction to the camshaft, and the outer periphery of the rotating body. A gap sensor is placed opposite to the sensor, and a signal corresponding to the distance between the outer periphery of the rotating body and the gap sensor is output from the gap sensor, so that the rotational phase of the camshaft relative to the crankshaft can be detected at an arbitrary timing. A valve timing control device for an internal combustion engine was proposed (see Patent Document 1).

According to this valve timing control device, the rotational phase of the camshaft with respect to the crankshaft can be detected regardless of the engine rotational speed. Therefore, even when the engine rotational speed is low, the valve timing control period and the rotational phase detection period are set. The valve timing control with high response and high accuracy can be realized.
JP 2005-299640 A

  However, the technique described in Patent Document 1 has a problem that the cost tends to be high because a rotating body having a special outer peripheral shape and a gap sensor are essential components. In addition, in an automobile, it is common to detect the rotational phase with the control logic of other engine equipment. However, the technique described in Patent Document 1 is different from the conventional technique in that the sensor required for detecting the rotational phase is changed. Therefore, it is necessary to change the control logic of other engine equipment, and there is a problem that man-hours increase.

  The present invention has been made to solve the problems of the prior art, and even when operating conditions such as the operating conditions of the internal combustion engine and the operating speed of the variable valve mechanism change, the feedback of the variable valve mechanism is provided. To provide a control device for a variable valve mechanism that can be controlled with high accuracy and that can be implemented at low cost, to provide a variable valve mechanism that is controlled by this control device, and to provide this control device An object of the present invention is to provide an internal combustion engine provided.

  In order to solve the above-described problems, the present invention firstly relates to a control device for a variable valve mechanism, and firstly estimates a state quantity of the variable valve mechanism using a dynamic model of the variable valve mechanism, State quantity estimation means for outputting a signal corresponding to the state quantity of the valve mechanism as a state quantity estimation value, and a model coefficient of the dynamic model output from the state quantity detection means and the state quantity estimation means And a coefficient correction means for correcting based on the estimated state quantity.

  Secondly, the present invention relates to a control device for a variable valve mechanism, and in the control device for the first variable valve mechanism, the state quantity estimation means includes a model coefficient of the dynamic model corrected by the coefficient correction means. Thus, the state quantity that complements the detection period of the state quantity detection means is estimated and used to control the variable valve mechanism.

  Thirdly, the present invention relates to the control device for the variable valve mechanism. In the control device for the first and second variable valve mechanisms, the variable valve mechanism changes the rotational phase of the camshaft with respect to the crankshaft. A variable valve timing mechanism for controlling the opening / closing timing of the intake valve and the exhaust valve, and the state quantity detection means from detecting the reference rotation position of the crankshaft to detecting the reference rotation position of the camshaft The state quantity estimating means is a variable valve that detects a rotation period of the camshaft relative to the crankshaft, and detects the rotation phase of the camshaft relative to the crankshaft. When the control cycle of the mechanism becomes longer, the state quantity is supplemented using the estimated state quantity estimated for each control period. And the configuration of controlling the variable valve mechanism.

  Fourthly, the present invention relates to a control device for a variable valve mechanism, and in the control devices for the first to third variable valve mechanisms, the model coefficient of the dynamic model corrected by the coefficient correction means is the variable motion mechanism. It was set as the dynamic friction coefficient in the sliding part of a valve mechanism.

  The present invention fifthly relates to a control device for a variable valve mechanism. In the control devices for the first to fourth variable valve mechanisms, the coefficient correction means is a state quantity detection value or a state of the variable valve mechanism. The model coefficient of the dynamic model is corrected based on the operating speed of the variable valve mechanism calculated from the estimated value.

  The present invention relates to a control apparatus for a variable valve mechanism, sixthly, in the control apparatus for the fifth variable valve mechanism, wherein the coefficient correction means sets a dynamic friction coefficient in accordance with an operating speed of the variable valve mechanism. The model coefficient is corrected by switching between two values, a large value and a small value.

  Seventhly, in the control device for the first to sixth variable valve mechanisms, the coefficient correction means is configured such that the state quantity detection means uses the state quantity detection means. When a state quantity is newly detected, the model coefficient of the dynamic model is corrected based on a deviation between the state quantity detection value and the state quantity estimated value, and when the state quantity is not detected, the model coefficient of the past dynamic model is maintained. It was configured to do.

  Further, the present invention relates to a variable valve mechanism, a state quantity detection unit that detects a state quantity of the variable valve mechanism and outputs a signal corresponding to the detected state quantity of the variable valve mechanism as a state quantity detection value. A state quantity estimating means for estimating a state quantity of the variable valve mechanism using a dynamic model of the variable valve mechanism, and outputting a signal corresponding to the estimated state quantity of the variable valve mechanism as a state quantity estimated value; Operated by a control device comprising a state quantity detection value output from the state quantity detection means and a coefficient correction means for correcting the model coefficient of the dynamic model based on the state quantity estimation value output from the state quantity estimation means Was configured to be controlled.

  Furthermore, the present invention relates to an internal combustion engine, detecting an intake valve and an exhaust valve, a variable valve mechanism for adjusting one of the opening / closing timing and lift amount of each valve, and a state quantity of the variable valve mechanism, Estimating the state quantity of the variable valve mechanism using a state quantity detection means for outputting a signal corresponding to the detected state quantity of the variable valve mechanism as a state quantity detection value and a dynamic model of the variable valve mechanism A state quantity estimating means for outputting a signal corresponding to the estimated state quantity of the variable valve mechanism as a state quantity estimated value, and a state quantity detection for outputting a model coefficient of the dynamic model from the state quantity detecting means. And a control device for a variable valve mechanism having a coefficient correction means for correcting the value based on the value and the state quantity estimated value output from the state quantity estimation means.

  According to the present invention, a state quantity estimating means for estimating a state quantity of a variable valve mechanism by using a dynamic model of the variable valve mechanism, and a model coefficient of the dynamic model are obtained as a state quantity in a control device for the variable valve mechanism. Since the state correction value is corrected based on the state quantity detection value output from the detection means and the state quantity estimation value output from the state quantity estimation means, the operating condition of the variable valve mechanism greatly varies during operation. Even in such a case, it is possible to estimate the state quantity with high accuracy, and by executing this state quantity estimation at high speed, it is possible to complement the state quantity between detection periods by the state quantity detection means. Therefore, highly accurate feedback control of the variable valve mechanism can be realized. In addition, since a sensor structure similar to that of the prior art can be employed, the cost of the apparatus can be reduced.

  Hereinafter, a control apparatus for a variable valve mechanism according to an embodiment, a variable valve mechanism controlled by the control apparatus, and an internal combustion engine including the control apparatus and the variable valve mechanism will be described.

  FIG. 1 is a control system diagram of an internal combustion engine according to the embodiment. An internal combustion engine 101, a variable valve mechanism 113 provided in the internal combustion engine 101, and an engine control unit (also a control device for the variable valve mechanism 113) Hereinafter, it is mainly composed of "ECU") 114. In the present embodiment, the ECU 114 also serves as a control device for the variable valve mechanism 113, but the control device for the variable valve mechanism 113 may be provided as an electronic circuit independent of the ECU 114.

  Air is sucked into the combustion chamber 106 of the internal combustion engine 101 through the intake pipe 102 and the intake valve 105. Further, the combustion exhaust in the combustion chamber 106 is released into the atmosphere through the exhaust valve 107.

  The intake valve 105 and the exhaust valve 107 are driven to open and close by cams provided on the intake side camshaft 134 and the exhaust side camshaft 110, respectively. The intake side camshaft 134 has a variable valve timing that is a variable valve mechanism. A mechanism (hereinafter abbreviated as “VTC”) 113 is provided. The intake camshaft 134 is connected to the crankshaft 120 via the VTC 113 and a sprocket and timing chain (not shown), and the exhaust camshaft 110 is connected to the crankshaft 120 via a sprocket and timing chain (not shown). In the present embodiment, the VTC 113 is provided only on the intake valve 105 side. However, the VTC 113 may be provided on the exhaust valve 107 side instead of the intake valve 105 side or together with the intake valve 105 side.

  The VTC 113 is a mechanism that changes the opening / closing timing of the intake valve 103 by changing the rotational phase of the intake camshaft 134 with respect to the crankshaft 120. In this embodiment, a spiral radial link type variable valve as will be described later. Adopt timing mechanism.

  Detection signals from various sensors described later are input to the ECU 114, and the electronic control throttle 104, the VTC 113, and the fuel injection valve 131 are controlled by arithmetic processing based on the detection signals.

  The various sensors include an accelerator opening sensor (APS) 116 for detecting the accelerator opening, an air flow meter 115 for detecting the intake air amount of the internal combustion engine 101, and a reference rotational position at a crank angle of 180 ° from the crankshaft 120. A crank angle sensor 117 for extracting the crank angle signal REF and a unit angle signal POS for each unit crank angle, a throttle sensor 118 for detecting the opening of the throttle valve 103a, and a water temperature sensor 119 for detecting the cooling water temperature Tw of the internal combustion engine 101 A cam sensor 132 and the like for taking out the cam signal CAM at the reference rotational position for each unit cam angle from the intake camshaft 134 are provided. In the cam sensor 132, the reference rotational position of the intake camshaft 134 is arranged at a value obtained by dividing 360 ° by the number of cylinders, that is, every 90 ° for in-line four cylinders and every 120 ° for V-type six cylinders.

  As shown in FIGS. 3 to 5, the VTC 113 includes an intake side camshaft (hereinafter simply referred to as “camshaft”) 134, a timing sprocket 302, an assembly angle operation mechanism 304, an operation force application unit 305, And a VTC cover. 3 is a cross-sectional view of the VTC 113, FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3, and FIG. 5 is a cross-sectional view taken along the line BB in FIG.

  The timing sprocket 302 is assembled to the front end portion of the camshaft 134 so as to be relatively rotatable, and is connected to the crankshaft 120 via a timing chain (not shown). The assembly angle operating mechanism 304 is disposed on the front side (left side in FIG. 3) of the timing sprocket 302 and the camshaft 134, and operates the assembly angle between the camshaft 134 and the timing sprocket 302. The operation force applying means 305 is disposed further forward of the assembly angle operation mechanism 304 and drives the mechanism 304. The VTC cover is attached across the cylinder head (not shown) of the internal combustion engine 101 and the front surface of the head cover, and covers the front surface of the assembly angle operation mechanism 304 and the operation force applying means 305 and its peripheral area.

  The timing sprocket 302 is formed in a short shaft cylindrical shape, and has a gear portion 303 that meshes with the timing chain on the outer periphery. And it is assembled | attached to the driven shaft member 307 couple | bonded with the front-end part of the cam shaft 134 so that rotation is possible. Further, on the front surface of the timing sprocket 302 (the surface opposite to the camshaft 134), as shown in FIG. 4, three radial grooves 308 having parallel side walls facing each other extend along the radial direction of the timing sprocket 302. It is formed as follows. The driven shaft member 307 is coupled to rotate integrally with the cam shaft 134. Three protrusions 309 projecting radially are integrally formed on the outer peripheral surface of the front side of the camshaft 134, and the base ends of the three links 311 can be rotated by pins 312 in each of the protrusions 309. It is connected to. In addition, a protruding portion 313 that is slidably engaged with each radial groove 308 is integrally formed at the tip of each link 311. In this way, each link 311 is connected to the driven shaft member 307 via the pin 312 in a state where each protrusion 313 is engaged with the corresponding radial groove 308, so that the distal end side of the link 311 applies an external force. When received and displaced along the radial groove 308, the timing sprocket 302 and the driven shaft member 307 are relatively rotated by the action of the link 311. In addition, a housing hole 314 that opens to the front side in the axial direction is formed at the tip of each link 311. In the accommodation hole 314, there are an engagement pin 316 having a spherical protrusion 316a that engages with a spiral groove 315, which will be described later, and a coil spring 317 that biases the engagement pin 316 forward (spiral groove 315 side). Contained. On the other hand, a disk-shaped intermediate rotating body 318 is rotatably supported on the front side of the protrusion 309 of the driven shaft member 307. The aforementioned spiral groove 315 having a semicircular cross section is formed on the rear side of the intermediate rotating body 318 (camshaft 134 side), and the engagement pin 316 at the tip of each link 311 rolls in the spiral groove 315. It is freely engaged. The spiral groove 315 is formed so as to gradually reduce the diameter along the rotation direction of the timing sprocket 302. Therefore, when the intermediate rotating body 318 rotates relative to the timing sprocket 302 in a delayed direction with the engaging pin 316 at the tip of each link 311 engaged with the spiral groove 315, the tip of each link 311 has a diameter. While being guided by the direction groove 308, it is guided by the spiral shape of the spiral groove 315 and moves inward in the radial direction. Conversely, when the intermediate rotator 318 is relatively displaced in the advance direction, it moves outward in the radial direction.

  The assembly angle operation mechanism 304 includes a radial groove 308 of the timing sprocket 302, a link 311, a protrusion 313, an engagement pin 316, a protrusion 309, an intermediate rotating body 318, a spiral groove 315, and the like. Then, when a turning operation force is input from the operation force applying means 305 to the intermediate rotating body 318, the tip of the link 311 is displaced in the radial direction through the engaging portion between the spiral groove 315 and the engaging pin 316, By the action of the link 311 and the protruding portion 309, it is transmitted as turning power that changes the assembly angle between the timing sprocket 302 and the driven shaft member 307, and hence the assembly angle between the timing sprocket 302 and the camshaft 134.

  The operating force applying means 305 generates a spring spring 319 that biases the intermediate rotator 318 in the rotation direction of the timing sprocket 302 and a braking force that rotates the intermediate rotator 318 in a direction opposite to the rotation direction of the timing sprocket 302. The hysteresis brake 320 is provided. Then, the ECU 114 controls the braking force of the hysteresis brake 320 according to the operating state of the internal combustion engine 101, whereby the intermediate rotating body 318 is rotated relative to the timing sprocket 302, and the rotational position can be maintained. Yes.

  The rotational phase (hereinafter simply referred to as “phase”) θdet of the VTC 113 detects the reference crank angle signal REF of the crank angle sensor 117 after detecting the reference cam angle signal CAM of the cam sensor 132 as shown in FIG. Based on the number of detections of the unit angle signal POS until this time, the ECU 114 calculates.

  As described above, the VTC 113 of the present embodiment is configured to move in the spiral groove 315 while the engagement pin 316 is kept in contact with the rotation of the intermediate rotating body 318. The lubrication state of the contact portion with the engagement pin 316 is changed from the fluid lubrication state to the boundary lubrication depending on the relative speed (operating speed of the VTC 113) between the spiral groove 315 and the engagement pin 316, the temperature / viscosity of the lubricating oil, and the engine speed Ne. Therefore, the dynamic friction coefficient of the contact portion also greatly changes as indicated by reference numerals 901, 902, and 903 in FIG. Therefore, in order to control the VTC 113 according to the embodiment with high accuracy, a control device having a configuration that can cope with a case where the dynamic friction coefficient of the contact portion greatly changes according to the operating condition of the VTC 113 is required. The engine speed Ne is calculated by the ECU 114 based on the cycle of the reference crank angle signal REF or the number of unit angle signals POS generated per unit time.

  Next, a part of the ECU 114 related to the control of the VTC 113 will be described with reference to FIGS.

  As shown in FIG. 6, the ECU 114 includes a target phase setting unit 600, a controller 601, a state quantity detection unit 602, and a state quantity estimation unit 603 as parts related to the control of the VTC 113. The VCT 113 is feedback controlled according to the procedure shown in FIG.

  That is, first, the target phase θtg is set by the target phase setting means 600 according to the driving state of the vehicle (step 701). The quantity representing the driving state of the vehicle includes the engine speed Ne and the intake pipe pressure. The target phase θtg is obtained in advance by calculation or experiment. Next, the state amount detection value θdet is detected by the state amount detection means 602 (step 702). Next, the estimated state quantity θobs is calculated by the state quantity estimating means 603 (step 703). The execution contents of the state quantity estimation means 603 will be described later. Next, the controller 601 calculates a command voltage Vi (step 704). A method for calculating the command voltage Vi will also be described later. Then, the calculated command voltage Vi is applied to the VTC 113, and the control flow is closed. The above control is repeated every minute time (for example, 10 ms).

The controller 601 is a feedback controller for PID control. As shown in FIG. 8, the controller 601 uses a deviation between the target phase θtg set by the target position setting unit 600 and the estimated state quantity θobs estimated by the state quantity estimating unit 603. The command voltage Vi is calculated based on the following formulas (1) to (4). Note that θobs is an estimated value of the phase calculated for each control period by a state quantity estimating means described later.

  As shown in FIG. 10, the state quantity estimation means 603 first calculates an estimated state quantity θobs from the command voltage Vi based on the following equation (5) using a dynamic model (VTC model) 1001 of the VTC 113. Next, the estimated error compensation unit 1002 calculates a compensation signal based on the deviation θFB between the detected state quantity θdet and the estimated state quantity θobs. The compensation signal is input to the VTC model 1001 and the coefficient correction unit 1003 and is used for error compensation described later. Furthermore, the speed acquisition means 1004 calculates the operating speed of the VTC 113 based on the detected state quantity θdet. The calculated operation speed is input to the coefficient correction unit 1003. The coefficient correction unit 1003 corrects the dynamic friction coefficient of the VTC model 1001 by correcting the dynamic friction coefficient based on the operation speed and the compensation signal. As a result, the state quantity estimation means 603 causes the dynamic friction within the state quantity estimation means to change from time to time based on the operating speed of the VTC 113, the phase detection value θdet, and the deviation θFB of the phase estimation value θobs with respect to the changing dynamic friction coefficient. While correcting the coefficient, θobs that complements the value between the sensor detection periods is obtained.

FIG. 11 is a block diagram of the state quantity estimation unit 603 according to the embodiment. The state quantity estimation means 603 of this example is configured based on a dynamic model of the VTC 113 expressed by the following equation.

  Hereinafter, each element of the state quantity estimation means 603 shown in FIG. 11 will be described based on the equation (5).

It is assumed that the relationship between the output torque τ of the hysteresis brake 320 provided in the VTC 113 and the hysteresis brake model 1101 of the state quantity estimation means in FIG. 11 and the input voltage V is expressed by the following equation (6) for simplicity.

  Of the model coefficients Kt, J, D, and K in equation (5), Kt, J, and K are constants that do not depend on the state, and D is a variable that varies depending on operating conditions. Therefore, the coefficient correction means 1102 is configured to correct the dynamic friction coefficient D from moment to moment. As indicated by reference numerals 901, 902, and 903 in FIG. 9, the dynamic friction coefficient includes a low speed operation region where the dynamic friction coefficient is large and a high speed operation region where the dynamic friction coefficient is small. Therefore, first, a speed correction cutting friction coefficient Dm as a base is set according to the operation speed. Next, the error between the actual dynamic friction coefficient and the speed correction dynamic friction coefficient Dm is corrected based on the deviation correction dynamic friction coefficient DFB obtained from the phase detection value θdet and the estimated error θFB of the phase estimation value θobs, and the dynamic friction coefficient D is calculated. To do.

FIG. 12 shows a processing procedure of the coefficient correction unit 1102. The calculation of the estimated phase θobs by the state quantity estimating unit 603 and the correction of the dynamic friction coefficient by the coefficient correcting unit 1102 are repeatedly executed every control cycle. First, in step 1201, it is determined whether the state quantity detection means has updated the phase. If it has been updated (Yes), the process proceeds to step 1202 and step 1205. Steps 1202, 1204, and 1208 are routines for executing the following equations (8), (9), and (10), and are routines for correcting the dynamic friction coefficient based on the detected phase θdett and the estimated phase θobs. Steps 1205 to 1208 are routines for executing the following equations (7) and (10), and are routines for correcting the dynamic friction coefficient based on the operating speed of the VTC 113. If it is determined in step 1201 that the state quantity detection means has not updated the phase (No), θFB = 0 is set, and the process proceeds to step 1204.

  However, DmL is larger than Dms. Further, DmL, Dms, and KD are obtained in advance by experiments or the like. Note that when the value of the expression (7) is switched in step 1205, ΣθFB in the expression (8) may be reset to 0 in step 1204. Further, K1 to K3 in FIG. 11 are obtained in advance by calculation or experiment.

FIG. 13 shows an operation example of the VTC 113 when the VTC 113 is controlled by the control device according to the embodiment. 13A shows the phase, FIG. 13B shows the phase deviation θFB, and FIG. 13C shows the dynamic friction coefficient of the state quantity estimating means. In FIG. 13, reference numeral 1301 indicates the target phase θtg of the VTC, reference numeral 1302 indicates the estimated phase θobs of the state quantity estimating means, reference numeral 1303 indicates the actual phase of the VTC, and reference numeral 1304 indicates the detected phase θdet. The target phase θtg changes at time t0. Due to the change in θtg, the command voltage Vi to the hysteresis brake 320 is output by the above-described equations (1) to (4), and the phase of the VTC 113 changes. The dynamic friction coefficient of the state quantity estimation means 603 before time t0 is a value near DmL as shown in FIG. At time t1, the state quantity detection means detects the detection phase θdet. Here, Yes is selected in step 1201 of FIG. Next, in step 1202, the phase deviation θFB is calculated. In step 1205, switching of Dm in the equation (1) is determined by the following equation (11).

  Note that Δt is the detection period of the state quantity detection means 602, and θdetz is the previous value of θdet. However, equation (11) may be processed in the estimated phase θobs instead of the detected phase θdet. The determination threshold value Vsh is obtained in advance by experiments or the like. Since the operation of the VTC 113 is small at time t1 and does not satisfy the expression (11), No is selected in step 1205, and Dm is set to DmL in step 1207. In step 1208, the dynamic friction coefficient D is calculated as shown in equation (10). The phase estimation and dynamic friction coefficient correction are repeated every control cycle. For this reason, it is executed even when the phase detection by the state quantity detection means is not executed. Here, as an example when the phase is not detected, an example of the control cycle t1I next to t1 is shown. If the phase is not detected, No is selected in step 1201 of FIG. In step 1203, θFB is set to zero. As a result, the DFB is maintained at the same value from the previous phase detection to the next phase detection. The previous value of Dm is also maintained, and the dynamic friction coefficient D is maintained.

  The above is an example when DmL is set to Dm in steps 1205 to 1207. As an example when DmS is set in Dm, time tM is taken as an example. At time tM in FIG. 13, the detected phase θdet moves greatly and satisfies the equation (11). Accordingly, Yes is selected in step 1205 of the flowchart of FIG. In step 1206, DmS, which is a dynamic friction coefficient close to the value when the dynamic friction coefficient becomes light, is set to Dm.

  When the VTC 113 moves to the vicinity of the target phase θtg, it is decelerated by the action of the controller 601 and approaches the target value. At this time, a transition is made from a region where the dynamic friction coefficient is small to a large region (tN in FIG. 13). At this time, DmL is set in Dm in the same manner as in the above-described setting of Dm, so that it is possible to cope with a change in the dynamic friction coefficient, and the estimation accuracy can be improved.

  Hereinafter, effects of the control device according to the present embodiment will be described.

  By setting the dynamic friction coefficient D of the state quantity estimation means as in the equations (7) to (10), the dynamic friction coefficient that varies according to the operating conditions can be corrected, and the phase can be estimated with high accuracy. . Further, by using the estimation error θFB for correction, a dynamic friction coefficient that changes every moment can be reflected in the estimation, and a control device that is robust against changes in state can be configured.

  In the present embodiment, the coefficient correction means is configured to correct the dynamic friction coefficient at the timing when the state quantity is detected as in equation (9). If correction is made at an arbitrary timing, correction is performed by comparing the past detection value with the current estimated value. For example, it is assumed that the phase θdete is detected at a certain time Te1. Assume that the estimated value θobs1 of the phase at this timing coincides with θdete, and the state quantity estimating means estimates accurately. At the next timing Te2, the estimated value θobs2 of the phase varies with the operation of the VTC 113. However, the detected θdete is not updated until the next detection, and even if the estimation accuracy is high, there is a difference between the detected value θdete and the estimated value θobs2. If the correction of the model coefficient is executed based on this difference, the phase estimation accuracy is deteriorated. Therefore, as in the control device according to the present embodiment, the state quantity estimation unit is configured to include a coefficient correction unit that corrects the model coefficient at the timing when the state quantity is detected and maintains the model coefficient at other timings. Thus, correction of an erroneous model coefficient based on the past detected state quantity as described above can be avoided, and deterioration of estimation accuracy can be avoided.

  Depending on the configuration of the VTC 113, sufficient estimation accuracy may be obtained even when KD is zero. At this time, the coefficient correction means may be configured to perform correction such that the dynamic friction coefficient is switched at two points, as in the correction of equation (7). With such a configuration of the coefficient correction means, it is not necessary to perform error feedback as shown in the equations (8) to (9), so that the calculation load and the memory usage of the ECU 114 can be reduced.

  Further, as described above, by estimating the phase of the variable valve mechanism using the dynamic model of the VTC 113 in which the dynamic friction coefficient with large fluctuation is corrected, the state quantity during the detection period of the state quantity detection unit is complemented and estimated. it can. By controlling using this estimated value, it is possible to reflect in the control the amount of state between detection periods that cannot actually be detected. Thereby, the phase control accuracy can be improved. Therefore, the state quantity detection means may be a long detection cycle that can be introduced at a low cost, and the cost of the entire variable valve system can be reduced.

  The control device according to the present embodiment can acquire the state quantity at the same calculation cycle as the control period by the state quantity estimation means even if the state quantity detection means has a detection cycle longer than the control period. By controlling using the estimated state quantity, the state quantity at each control timing can be reflected in the control, and the phase of the variable valve mechanism can be controlled with high accuracy. Therefore, even if the variable valve mechanism is controlled using the detection state quantity of the state quantity detection means constituted by the cam sensor 132 and the crank angle sensor 117 that are conventionally mounted on the automobile, the phase of the variable valve mechanism is accurately determined. It can be controlled well. As a result, it is not necessary to add a new sensor to detect the phase, and it is not necessary to change the control logic of the control device, so that the cost of the entire variable valve mechanism can be reduced.

  The dynamic model of the VCT 113 shown in the equation (5) includes a product of the operation speed and the dynamic friction coefficient. Therefore, when the dynamic friction coefficient moves greatly as in the VCT 113 according to the present embodiment, the fluctuation of the dynamic friction coefficient greatly affects the estimation accuracy. Therefore, by configuring the state quantity estimating means so as to correct the dynamic friction coefficient by the coefficient correction means, the dynamic friction coefficient can be corrected with less time delay according to the equation (7), and more accurately according to the equations (8) to (9). Can be implemented. As a result, the phase can be estimated accurately with little time delay.

  FIG. 14 shows an estimation phase 1402 in the case of using a state quantity estimation means that performs correction calculation only by the deviation between the detection phase βdet and the estimation phase βobs, and this embodiment that corrects the dynamic friction coefficient according to the operating condition shown in equation (7). The estimated phase 1302 in the case of using the state quantity estimating means according to the embodiment is shown in comparison.

  When the state quantity estimation means that performs correction calculation only with the deviation between the detected phase βdet and the estimated phase βobs is used, the dynamic friction coefficient decreases as the operating speed of the VTC 113 increases (see FIG. 9), and the target phase θtg at time T1. Is changed before time T1, the difference between the detected phase βdet and the estimated phase βobs is small, so that the dynamic friction coefficient based on the deviation is not sufficiently corrected. In this example, the dynamic friction coefficient of the state quantity estimation means is set smaller than the actual dynamic friction coefficient. For this reason, in the vicinity of time T1 when the VTC 113 starts to operate, the dynamic friction coefficient of the state quantity estimating means is too small and the phase is moving too much. This excessive movement of the phase is caused by an error in the dynamic friction coefficient between the VTC 113 and the state quantity estimating means. Immediately after the operation is started, the deviation between the state quantity detection value and the state quantity estimation value is small, and the deviation correction is not sufficiently performed.

  On the other hand, in the control device according to the present embodiment, the coefficient correction means is configured to switch the value of the dynamic friction coefficient between when the operation speed is low and when the operation speed is high as in equation (7). When the operation speed of the VTC 113 is low, the dynamic friction coefficient between the VTC 113 and the state quantity estimation means is set to a close value as described above, so that the phase estimation accuracy can be increased immediately after the operation of the VTC 113 is started. Further, if only the deviation correction of the equations (8) to (9) is performed, a long time is required until the dynamic friction coefficient of the state quantity estimating means reaches the actual dynamic friction coefficient. The fact that much time is spent correcting the dynamic friction coefficient causes a situation in which the time for executing the phase estimation becomes long in the state where the dynamic model of the state quantity estimation means is away from the actual dynamic characteristics of the VTC 113. Therefore, the phase estimation accuracy greatly deteriorates until the dynamic friction coefficient of the state quantity estimation means reaches the actual dynamic friction coefficient. Therefore, as shown in the equation (7), when the dynamic friction coefficient of the state quantity estimating means is greatly decreased in accordance with the decrease of the dynamic friction coefficient, the time delay in correction can be reduced. In this way, by correcting the dynamic friction coefficient based on the operating speed of the VTC 113, the estimation accuracy can be increased and the control accuracy can be improved.

  In addition, the control device for the variable valve mechanism according to the present embodiment provides a highly accurate phase even if a variable valve mechanism whose mechanism characteristics vary depending on operating conditions is combined with a state quantity detection unit having a long detection cycle. Control can be realized. As a result, the allowable range of fluctuations in the mechanism characteristics of the variable valve mechanism can be expanded, and the degree of freedom and tolerances of the part shapes that have a large influence on the mechanism characteristics of the variable valve mechanism can be increased. The controllability of the mechanism phase can be improved. This avoids a phase overshoot that can cause actuator damage. By avoiding the phase overshoot, it is not necessary to design the strength of the variable valve mechanism to withstand damage due to overshoot, and the variable valve mechanism can be reduced in size and weight.

  By mounting a variable valve system configured using a control apparatus configured as in the present invention on a vehicle, even with a variable valve mechanism whose mechanism characteristics fluctuate, the opening and closing timings of the intake valve and the exhaust valve The lift amount can be controlled with high accuracy, and the intake air amount and exhaust amount of the combustion chamber can be controlled with high accuracy. Therefore, it is possible to accurately control the intake air amount and the exhaust amount that are optimal for the operating conditions, and it is possible to reduce the concentration of harmful substances in the exhaust gas and improve the fuel consumption. Further, by avoiding overshooting of the intake air amount and the exhaust air amount due to the phase behavior of the variable valve mechanism, it is possible to avoid an unexpected change in the engine output of the driver due to a change in the intake air amount and the exhaust air amount. .

  In the above embodiment, the coefficient correction by the coefficient correction unit is performed based on the operating speed of the VTC 113. However, it has been found that the operating conditions affecting the dynamic friction coefficient include the engine speed Ne and the temperature and viscosity of the lubricating oil. Therefore, the equation (7) may be expanded to switch Dm or set a value to be switched with an amount (for example, the water temperature sensor output Tw) reflecting the engine speed and the temperature and viscosity of the lubricating oil. .

1 is a control system diagram of an internal combustion engine according to an embodiment. It is a figure which shows the calculation method of a rotation phase. It is sectional drawing of the variable valve mechanism which concerns on embodiment. It is AA sectional drawing (most retarded angle state) of FIG. It is BB sectional drawing of FIG. It is a control block of the control apparatus which concerns on embodiment. It is a flowchart which shows the control procedure performed with the control apparatus which concerns on embodiment. 3 is a block diagram of a controller 601. FIG. It is a figure which shows the change of the dynamic friction coefficient of the variable valve mechanism which concerns on embodiment. It is a block diagram of the state quantity estimation means which concerns on embodiment. It is a block diagram of the state quantity estimation means which concerns on embodiment. It is a flowchart which shows the coefficient correction | amendment procedure of the dynamic model performed with the control apparatus which concerns on embodiment. It is a graph which shows the behavior of the variable valve mechanism controlled using the control apparatus which concerns on embodiment. It is a graph which shows the comparison of the behavior of a variable valve mechanism when it controls using the control apparatus only with the coefficient correction | amendment of the dynamics model based on an estimation error, when it controls using the control apparatus which concerns on embodiment.

Explanation of symbols

101 Internal combustion engine 105 Intake valve 107 Exhaust valve 113 Variable valve timing mechanism (VTC)
114 Engine control unit (ECU)
117 Crank angle sensor 120 Crankshaft 132 Cam sensor 134 Intake side camshaft 302 Timing sprocket 304 Assembly angle operating mechanism 305 Operating force applying means 600 Target phase setting means 601 Controller 602 State quantity detecting means 603 State quantity estimating means 1001 VTC model 1002 Estimated error compensation unit 1003 Coefficient correction unit 1004 Speed acquisition unit

Claims (9)

A state quantity estimating means for estimating a state quantity of the variable valve mechanism using a dynamic model of the variable valve mechanism, and outputting a signal corresponding to the estimated state quantity of the variable valve mechanism as a state quantity estimated value;
Coefficient correction means for correcting the model coefficient of the dynamic model based on the state quantity detection value output from the state quantity detection means and the state quantity estimation value output from the state quantity estimation means. Control device for variable valve mechanism. The control apparatus for a variable valve mechanism according to claim 1,
The state quantity estimation means estimates a state quantity that complements the detection period of the state quantity detection means based on the model coefficient of the dynamic model corrected by the coefficient correction means, and is used for control of the variable valve mechanism. A control device for a variable valve mechanism. In the control apparatus for a variable valve mechanism according to any one of claims 1 and 2,
The variable valve mechanism is a variable valve timing mechanism that controls the opening and closing timing of the intake valve and the exhaust valve by changing the rotational phase of the camshaft with respect to the crankshaft.
The state quantity detection means detects a rotation phase from a rotation angle of the crankshaft from detection of a reference rotation position of the crankshaft to detection of a reference rotation position of the camshaft.
The state quantity estimating means estimates for each control period when the rotation period of the camshaft decreases and the detection period of the rotation phase of the camshaft relative to the crankshaft becomes longer than the control period of the variable valve mechanism. A control device for a variable valve mechanism, wherein a state variable is supplemented using an estimated value of the state variable to control the variable valve mechanism. In the state quantity estimation means of the control device for the variable valve mechanism according to any one of claims 1 to 3,
A control apparatus for a variable valve mechanism, wherein the model coefficient of the dynamic model corrected by the coefficient correction means is a dynamic friction coefficient in a sliding portion of the variable valve mechanism. The control apparatus for a variable valve mechanism according to any one of claims 1 to 4,
The coefficient correction means corrects the model coefficient of the dynamic model based on an operating speed of the variable valve mechanism calculated from a state quantity detection value or a state quantity estimation value of the variable valve mechanism. Control device for variable valve mechanism. In the control apparatus of the variable valve mechanism according to claim 5,
The coefficient correction means corrects the model coefficient by switching between a large value and a small value of the dynamic friction coefficient according to the operating speed of the variable valve mechanism, and corrects the model coefficient. . The control apparatus for a variable valve mechanism according to any one of claims 1 to 6,
When the state quantity detection unit newly detects a state quantity of the variable valve mechanism, the coefficient correction unit is configured to model the dynamic model based on a deviation between the state quantity detection value and the state quantity estimation value. A control apparatus for a variable valve mechanism, wherein the coefficient is corrected and the model coefficient of the past dynamic model is maintained when the coefficient is not detected.   It is possible to detect the state quantity of the variable valve mechanism by using a state quantity detection means that outputs a signal corresponding to the detected state quantity of the variable valve mechanism as a state quantity detection value and a dynamic model of the variable valve mechanism. State quantity estimation means for estimating a state quantity of the variable valve mechanism and outputting a signal corresponding to the estimated state quantity of the variable valve mechanism as a state quantity estimation value; and a model coefficient of the dynamic model as the state quantity detection means The operation is controlled by a control device including a state quantity detection value output from the state quantity and a coefficient correction means for correcting based on the state quantity estimation value output from the state quantity estimation means. mechanism.   An intake valve and an exhaust valve; a variable valve mechanism for adjusting any of the opening / closing timing and lift amount of each of these valves; and a state quantity of the variable valve mechanism detected by detecting a state quantity of the variable valve mechanism A state quantity detection means for outputting a signal corresponding to the quantity as a state quantity detection value; and a state quantity of the variable valve mechanism is estimated using a dynamic model of the variable valve mechanism, and the estimated variable valve mechanism A state quantity estimating means for outputting a signal corresponding to the state quantity as a state quantity estimated value, and a model coefficient of the dynamic model is outputted from the state quantity detecting means and the state quantity estimating means. An internal combustion engine comprising: a variable valve mechanism control device including coefficient correction means for correcting based on the estimated state quantity.

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