JP2009257180A - Control device for variable valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately control instantaneous rotation phase by eliminating influence of torque fluctuation caused by mechanical play in a variable valve train. <P>SOLUTION: This control device controls the variable valve train 113 comprising a drive member having rotation from a crankshaft transmitted, a driven member connected to a camshaft on which alternating torque acts and having torque transmitted thereto from the drive member, a phase change member 304 changing relative rotation phase between the drive member and the driven member, and an operation force applying member 305 applying operation force to the phase change member. The control device includes a torque fluctuation determination means 701 determining timing of change over of the alternating torque to a positive side or a negative side based on the cam angle of a cam provided on the camshaft and crank angle of the crankshaft, and a command correction means 702 outputting correction control command Va for making short time operation force resisting the alternating torque generated right after determination timing to the operation force apply member 305 at the determination timing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a variable valve mechanism that changes the opening / closing timing of an intake valve or an exhaust valve of an internal combustion engine by variably controlling the rotational phase of a camshaft with respect to a crankshaft.

  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. The valve timing of the mechanism is feedback controlled.

Further, as a conventional example of a control device for a variable valve timing mechanism for ensuring quick operation responsiveness when changing valve timing and stabilizing when maintaining a predetermined valve timing, for example, disclosed in Patent Document 1 Technology has been developed. According to this technique, in a variable valve timing mechanism that varies the valve timing by hydraulically driving a ring gear interposed between a timing pulley and a camshaft, a control valve that controls the ring gear is provided with a torque fluctuation of the camshaft. It is disclosed that duty control is synchronized with a phase that is reversed with respect to the cycle, whereby oil pressure that is periodically applied to the ring gear is periodically applied to the ring gear due to torque fluctuation of the camshaft. It is described that acting on the thrust force to cancel each other out, the fluctuation of the resultant force becomes small.
JP 2001-65373 A

  However, in the above-mentioned Patent Document 1, since correction is performed using the average value of torque fluctuation, the average influence of torque fluctuation can be canceled out, but the influence cannot be canceled every moment. Therefore, when a machine including mechanical play is controlled, play is greatly affected by torque fluctuation at the moment when the direction of torque changes. For this reason, disadvantages such as deterioration of control accuracy, deterioration of the machine itself, and hitting sound occur. In addition, since correction is performed using the average value of torque fluctuation, there is a problem that the rotational phase that changes due to torque fluctuation cannot be suppressed.

  An object of the present invention is to provide a control device for a variable valve mechanism that accurately controls the rotational phase from moment to moment without the influence of torque fluctuations caused by mechanical backlash of the variable valve mechanism.

In order to solve the above problems, the present invention mainly adopts the following configuration.
A drive member to which rotation is transmitted from the crankshaft, a driven member connected to a camshaft to which an alternating torque is applied and a rotational force is transmitted from the drive member, and a relative rotation phase between the drive member and the driven member is changed. A control device for controlling a variable valve mechanism comprising a phase change member and an actuating force applying member for applying an actuating force to the phase change member, wherein the control device is configured such that the alternating torque of the camshaft is positive or negative And a correction control command that outputs a short-time operating force to the alternating torque immediately after the detected timing to the phase change member at the detected timing.

  In addition, a drive member to which rotation is transmitted from the crankshaft, a driven member connected to a camshaft to which an alternating torque acts and a rotational force is transmitted from the drive member, and a relative rotational phase between the drive member and the driven member A control device for controlling a variable valve mechanism comprising a phase changing member to be changed and an operating force applying member for applying an operating force to the phase changing member, wherein the control device is configured such that the alternating torque of the camshaft is positive or A timing immediately before switching to the negative side is detected, and a correction control command for outputting a short-time operating force against the alternating torque after switching at the timing immediately before the detection to the phase change member is output. Further, in the control device, the immediately preceding timing is determined so that the timing at which the operation of the phase change member is terminated by the operating force matches the timing at which the alternating torque of the camshaft is switched to the positive side or the negative side. And

  In addition, a drive member to which rotation is transmitted from the crankshaft, a driven member connected to a camshaft to which an alternating torque acts and a rotational force is transmitted from the drive member, and a relative rotational phase between the drive member and the driven member A control device for controlling a variable valve mechanism comprising a phase changing member to be changed and an operating force applying member for applying an operating force to the phase changing member, wherein the control device is a cam of a cam provided on the camshaft. Torque fluctuation judging means for judging the timing at which the alternating torque is switched to the positive side or the negative side based on the angle and the crank angle of the crankshaft, and a short time against the alternating torque immediately after that at the judged timing And a command correcting means for outputting a correction control command for generating the operating force to the operating force applying member.

  According to the present invention, it is possible to accurately control the rotational phase every moment without the influence of torque fluctuation caused by the mechanical play of the variable valve mechanism. In addition, since the momentary operating force is applied to the variable valve mechanism so that the mechanical backlash is eliminated at the timing when the cam torque, which is an alternating torque, switches to the positive side or the negative side, the mechanical backlash can be quickly eliminated. It is possible to suppress hitting sound and impact deterioration due to movement through the play.

  Further, by providing the duty control unit on the control input side to the variable valve mechanism, the variable valve mechanism can be easily controlled by changing the pulse width or the pulse height.

  Further, by detecting the engine speed or temperature and providing a mode that prohibits the control according to the present invention when the engine speed exceeds a predetermined value and the temperature is lower than the predetermined value, Reduction can also be implemented.

  A control apparatus for a variable valve mechanism according to an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram of an internal combustion engine of a vehicle equipped with a control device for a variable valve mechanism according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the internal structure of the variable valve mechanism to which the control device according to this embodiment is applied. FIG. 3 is a cross-sectional view showing the cross section taken along the line AA of FIG. FIG. 4 is a cross-sectional view showing a hysteresis brake in the variable valve mechanism, showing a cross section taken along line BB of FIG. FIG. 5 is a diagram showing an arrangement structure of the cam shaft, cam, valve spring, and intake valve of the engine. FIG. 6 is a diagram showing the relationship between the camshaft rotation angle and the fluctuation torque (cam torque) in a four-cylinder engine.

  FIG. 7 is a control block diagram when the control device according to the present embodiment is applied to a variable valve mechanism (VTC). FIG. 8 is a flowchart showing the determination procedure of the torque fluctuation determination means in the control device according to the present embodiment. FIG. 9 is a map in which the alternating torque of the camshaft changes depending on the camshaft rotation angle.

  FIG. 10 is an explanatory view showing the action direction of mechanical backlash and cam torque in the spiral radial link type variable valve mechanism according to this embodiment. FIG. 11 is a diagram showing a structure for closing mechanical backlash in the variable valve mechanism according to the present embodiment.

FIG. 12 is a flowchart showing the correction procedure of the command correction means in the control apparatus according to this embodiment. FIG. 13 is a timing chart showing a control mode in the control device for the variable valve mechanism according to the embodiment of the present invention. FIG. 14 is provided with a duty control unit on the control input side to the variable valve mechanism according to this embodiment. FIG. 15 is an explanatory diagram showing phase fluctuation due to mechanical play in the variable valve mechanism according to this embodiment. . FIG. 16 is an explanatory diagram showing the occurrence of cam fluctuation torque (cam torque) and the influence on the VTC phase in a four-cylinder engine. FIG. 17 is an explanatory diagram showing the control timing and control structure of mechanical backlash filling in the variable valve mechanism according to the present embodiment.

  FIG. 1 is a configuration diagram of an internal combustion engine of a vehicle equipped with a control device for a variable valve mechanism according to an embodiment of the present invention. The basic configuration of the present embodiment includes an internal combustion engine (engine) 101, an engine control unit (ECU) 114, a variable valve mechanism 113, and a control device. Although the control device is assumed to be mounted in the ECU 114, it may be provided independently as an electronic circuit having an equivalent function.

  In FIG. 1, air is sucked into the combustion chamber 106 of the internal combustion engine 101 through the intake pipe 102 and the intake valve 105. Combustion exhaust is discharged from the combustion chamber 106 through the exhaust valve 107 into the atmosphere. 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 as a variable valve mechanism. A mechanism (hereinafter referred to as VTC) 113 is provided.

  Here, the intake side camshaft 134 and the exhaust side camshaft 110 are driven by being linked to the crankshaft 120 via the VTCl 13, a sprocket (not shown) and a timing chain, respectively. The VTCl 13 is a mechanism that changes the opening / closing timing of the intake valve 105 by changing the rotational phase of the intake camshaft 134 with respect to the crankshaft 120. As an example, in this embodiment, a known spiral radial link type (for example, JP 2004-11537 A) variable valve timing mechanism (an outline will be described later) is employed.

  In this embodiment, an electromagnetic variable valve mechanism is assumed, but the present invention is not limited to this. In addition, although a spiral radial link type variable valve mechanism is assumed, the present invention is not limited to this. In this embodiment, the VTC 113 is provided only on the intake side camshaft 134. However, the intake side camshaft 110 is provided with the VTC 113 instead of the intake side camshaft 134 or together with the intake side camshaft 134. There may be.

  The ECU 114 receives various detection signals from various sensors, and controls various operation units such as the VTCl 13 by arithmetic processing based on these detection signals. As these various sensors, an air flow meter 115 for detecting the intake air amount Qa, a crank for taking out the reference crank angle signal REF from the crankshaft 120 at the reference rotational position for every crank angle of 180 ° and taking out the unit angle signal POS for each unit crank angle. An angle sensor 117, a water temperature sensor 119 that detects the coolant temperature Tw of the engine 101, and a cam sensor 132 that extracts the cam signal CAM from the intake camshaft 134 at a reference rotational position for each unit cam angle are provided.

  The reference rotational position of the intake side camshaft 134 is arranged 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. Otherwise, the internal combustion engine of this embodiment is an in-line four cylinder).

  The engine speed Ne is calculated by the ECU 114 based on the period of the reference crank angle signal REF or the number of unit angle signals POS generated per unit time. The rotational phase of the VTCl 13 (hereinafter simply referred to as phase) is the number of detections of the unit angle signal POS from when the reference cam angle signal CAM of the cam sensor 132 is detected until the reference crank angle signal REF of the crank angle sensor 117 is detected. Is calculated by the ECU 114 (see FIG. 18). The cam sensor 132 includes a cam target (not shown) that rotates in conjunction with the rotation of the intake camshaft 134 and a magnetic proximity sensor. On the outer periphery of the cam target, a plurality of protrusions that match the number of cam peaks of the intake side camshaft 134 are formed. When the cam target is rotated, the magnetic proximity sensor detects the passage of the protrusion, and the ECU 114 detects the reference rotational position of the intake side camshaft 134.

  Next, the structure of VTCl13 regarding this embodiment is demonstrated based on FIGS. 2 is a cross-sectional view of the VTCl 13, FIG. 3 represents a cross-section AA in FIG. 2, and FIG. 4 represents a cross-section BB in FIG. 2.

  The VTCl 13 includes an intake side camshaft (hereinafter simply referred to as a camshaft) 134, a timing sprocket 302, an assembly angle operation mechanism (phase change member) 304, an operation force application means (operation force application member) 305, And a VTC cover.

  The timing sprocket 302 is a drive member that is assembled to the front end portion of the camshaft 134 so as to be relatively rotatable, is linked to the crankshaft 120 via a timing chain (not shown), and rotation is transmitted from the crankshaft 120. is there. The assembly angle operation mechanism 304 is disposed on the front side (left side in FIG. 2) of the timing sprocket 302 and the camshaft 134, and operates the assembly angle (phase) between the camshaft 134 and the timing sprocket 302. The operating force applying means 305 is disposed further forward of the assembly angle operation mechanism 304 and drives the assembly angle operation mechanism 304. As shown in FIG. 3, the radial sprocket 302 is formed with three radial grooves 308 (radial guides) in the radial direction of the timing sprocket 302.

  The assembly angle operation mechanism 304 will be described with reference to FIG. The assembly angle operation mechanism 304 includes a protrusion 309, a link 311, an engagement pin 316, a vortex disk 318, and a radial groove 308. The protrusion 309 is a driven member that is coupled to the camshaft 134 so as to rotate together. The base ends of the three links 311 are rotatably connected to the protrusions 309 by pins 312. The other end of each link 311 is slidably engaged with each radial groove 308. With this configuration, the slider link mechanism is formed by the protrusion 309, the link 311, and the radial groove 308.

  When the distal end side of the link 311 receives an external force and is displaced along the radial groove 308, the timing sprocket 302 and the camshaft 134 (integrated with the protruding portion 309) are relatively rotated by the action of the link 311. Further, an engaging pin 316 having a spherical protrusion 316a is assembled at the tip of each link 311. The engagement pin 316 is slidably engaged with a vortex groove 315 (described later) formed in a vortex disk 318 that is rotatably supported in front of the protrusion 309. The vortex groove 315 is a groove having a semicircular cross section formed in the vortex disk 318, and is formed so as to gradually reduce the diameter along the rotation direction of the timing sprocket 302.

  When the vortex disk 318 as an intermediate member is rotated relative to the timing sprocket 302 in the delay direction (retard angle direction) by the operation force applying means 305, the distal end portion of each link 311 is guided to the radial groove 308. However, it is guided to the spiral shape of the spiral groove 315 and moves inward in the radial direction. Therefore, the timing sprocket 302 and the camshaft 134 rotate relative to each other in the advance direction. Conversely, when the vortex disk 318 is relatively rotated in the advance direction (advance direction), the vortex disk 318 moves radially outward, and the timing sprocket 302 and the camshaft 134 are relatively rotated in the retard direction.

  The operating force applying means 305, which is an actuator, has a mainspring 319 that biases the vortex disk 318 in the rotational direction of the timing sprocket 302 and a braking force that rotates the vortex disk 318 in a direction opposite to the rotational direction of the timing sprocket 302. And a hysteresis brake 320 that is generated. Then, the ECU 114 controls the braking force of the hysteresis brake 320 according to the operating state of the internal combustion engine 101, thereby rotating the vortex disk 318 relative to the timing sprocket 302 and maintaining the rotational position. Yes. FIG. 4 is a diagram showing a detailed structure of the hysteresis brake.

  As described above, the variable valve mechanism according to the present embodiment is mechanically coupled between the vortex groove 315 and the engagement pin 316 and the slider link mechanism (protrusion 309, link 311, radial groove 308). It is configured to include various backlash. Therefore, the operating characteristics of the variable valve mechanism are greatly different between a state where the members are clogged (having no backlash) and the members are engaged, and a state where there is a backlash. For this reason, when a torque that causes the operating direction of the variable valve mechanism to change frequently is applied, a state in which the output of the actuator cannot be transmitted to the original transmission system frequently occurs due to backlash. For this reason, when there is a vibration disturbance or when following a vibration control command, there arises a problem that the variable valve mechanism cannot exhibit its original performance. In addition, when torque is transmitted from the camshaft 134 in the presence of backlash, there are problems such as the sound of a backlash being clogged and the variable valve mechanism being damaged.

  The present embodiment ensures high disturbance resistance even with a mechanism that includes play. Further, even with a mechanism that includes backlash, it is possible to reduce the sound of hitting and the breakage of the variable valve mechanism.

  Next, phase fluctuation due to backlash of the variable valve mechanism according to this embodiment will be qualitatively described with reference to FIG. In the state shown by the solid line in FIG. 15, the upper side of the engaging pin 316 and the upper edge of the vortex groove 315 are in contact with each other, and the phase θ is between the crankshaft reference angle and the protrusion 309 integral with the camshaft. Is formed. In this solid line state, a backlash as illustrated is generated between the lower side of the engagement pin 316 and the lower edge of the vortex groove 315. Here, when the engagement pin shifts as shown by the dotted line in the figure by the action of the cam fluctuation torque from the camshaft, the link 311 moves as shown in the figure, and as a result, the phase shifts from θ shown in the figure to the amount of phase fluctuation. Only get bigger. As described above, the output from the operating force applying means 305 (actuator) is not transmitted to the camshaft due to the idle shift of the loose portion. Further, when cam fluctuation torque is transmitted from the camshaft, the rattling portion is moved to generate a hitting sound.

  In general, the fluctuation factors of the vibration disturbance torque acting on the camshaft include opening / closing of intake / exhaust valves and various engine devices driven by the camshaft. Here, a torque variation (hereinafter referred to as alternating torque) due to opening / closing of the intake valve 105 will be described as an example.

  FIG. 5 shows the configuration of the intake valve 105, the camshaft 134, the cam 501, and the valve spring 502 of the in-line four-cylinder engine. The cam 501 is assembled to the camshaft 134 so as to rotate integrally with the camshaft 134. The intake valve 105 is opened by a cam 501 and closed by a valve spring 502. By driving the opening / closing of the intake valve 105, a periodically varying torque acts on the camshaft 134 with respect to the rotation angle of the camshaft 134, as shown in FIG. The alternating torque is uniquely determined by the profile of the cam 501 and the assembly phase of the cam 501 for each cylinder. The direction of the torque is switched from the positive side to the negative side after θR from the angle at which the torque takes a peak (this is the reference rotational position). Further, the torque direction is switched from the negative side to the positive side after θA when the torque takes a peak.

  Next, a mode in which the phase of the variable valve mechanism according to the present embodiment vibrates due to the fluctuation torque of the camshaft will be qualitatively described with reference to FIG. The illustration shows an example of four cylinders. The camshaft (cam shaft) rotates in a constant rotational direction, and the camshaft is delayed by a torque (second cam from the left) due to the cam position and the reaction force of the valve spring. ) And advancing torque (fourth cam from the left) are generated periodically (cam fluctuation torque), and this cam torque acts on the VTC. The VTC phase is formed in a state where the VTC torque by the actuator and the cam torque are balanced. Further, a rotating body having four protrusions indicating the reference position of the camshaft or the cam at the right end of the camshaft and a cam sensor for detecting these protrusions are provided.

  Next, FIG. 7 shows the configuration of the control device for the variable valve mechanism according to the present embodiment. The inside of the dotted line in FIG. 7 is a configuration of a conventionally proposed general control device, and the components indicated by reference numerals 701 and 702 are new configurations relating to the present embodiment.

  In the present embodiment, the control device sets a target setting means 703 for setting the target phase θtg of the variable valve mechanism based on operating conditions such as the engine speed Ne and the intake pipe flow rate Qa, and targets the VTCl 13 based on the target phase θtg. A feedforward controller 704 that outputs a control command Vff necessary to drive the phase θtg, and a control command Vfb that stably drives the VTCl13 based on the difference between the target phase θtg and the actual phase θr of the VTCl13. The feedback controller 706 for output, the phase acquisition means 705 for acquiring the phase of the VTCl 13, the torque fluctuation determination means 701 for determining the timing at which the direction of the torque action changes based on the crank angle and the cam angle, and this determination Correction that gives VTCl13 instantaneous differential force that counters (counters) torque fluctuation at timing Command correcting means 702 for outputting a control command Va.

  FIG. 8 shows a flowchart of the torque fluctuation determination means 701 (see FIG. 7) of the control device according to this embodiment. FIG. 12 shows a flowchart of the command correction means 702 (see FIG. 7) of the control device according to this embodiment. These calculations are executed every calculation cycle Tstep (for example, 10 ms) of the ECU 113.

  The torque fluctuation determining means 701 calculates the magnitude of the alternating torque acting on the camshaft 134 in steps S801 to 806, which are alternating torque calculation units, and briefly describes the steps in steps S807 to 811 which are timing flag calculation units. Thus, based on the calculated alternating torque, the timing and direction in which the alternating torque component switches between the positive side and the negative side are determined, and the determination result is output to the command correction means 702.

  First, in S801, the engine rotational speed Ne (corresponding to the crank speed) is acquired based on the signal from the crank angle sensor, converted into a unit for the engine rotational angle for each calculation cycle Tstep of the ECU 113, and stored in New. . In S802, based on the cam angle signal CAM of the cam angle sensor 132, it is determined whether the camshaft 134 is at the reference rotation position. Specifically, the position at which four magnetic projections are detected by the magnetic sensor in the cam angle sensor of FIG. 16 may be the reference rotational position of the camshaft.

  In S803 to 804, the rotation angle of the camshaft 134 is estimated based on the result determined in S802. As shown in FIG. 6, the alternating torque is determined depending on the rotation angle of the camshaft 134. For this reason, if the reference rotation position is detected, the magnitude of the alternating torque can be estimated. If it is determined Yes in S802, it is the reference rotation position, and the camshaft rotation angle θcam is reset to 0 in S803. If it is determined No in S802, the current magnitude of θcam is set based on Equation 1 in S804.

θcam = θcam + Newow × Tstep (Formula 1)
In Equation 1, the rotation angle Newow × Tstep from the previous calculation to the present is added to the previous θcam to obtain the current θcam. In S805, the previous alternating torque is stored as the alternating torque (to determine the direction of the cam torque in S808 described later).

  In S806, the current magnitude of the alternating torque is calculated. The alternating torque τcam is calculated based on θcam with reference to a map f of the magnitude of the alternating torque obtained in advance through experiments or the like (see FIG. 9).

  As described above, the magnitude of the alternating torque varies depending on θcam. Using this property, the alternating torque can be mapped as shown in FIG. By referring to the map for calculating τcam, the calculation load can be reduced. Specifically, it is possible to estimate θR or θA shown in FIG. 6 by detecting the camshaft reference rotational position with the cam angle from the cam angle sensor and detecting the passage of time with the POS signal of the crank angle sensor. The timing at which the cam fluctuation torque crosses the zero level or the timing immediately before it can be detected. A map f in FIG. 9 is a map showing the alternating torque for one cam. Since the alternating torque due to other cams is substantially the same change, it can be expressed by one map. When the alternating torque behavior differs depending on the cam, the torque change for one rotation of the camshaft 134 may be mapped.

  In S807, it is determined whether or not τcam in S806 is zero. In other words, it is determined whether or not the alternating torque, that is, the camshaft fluctuation torque crosses the 0 line. If it is determined No in S807, the alternating torque is an area where the positive and negative are not switched, and the timing determination flag flg_ctrl is set to 0 in S811. If it is determined Yes in S807, the alternating torque is switched between positive and negative. Therefore, in S808 to S810, flg_ctrl is set to a determination value corresponding to the direction. That is, in S808, the sign of the alternating torque magnitude τcamz at the previous calculation stored in S805 is determined. If it is determined Yes in S808, 1 is set to flg_ctrl in S809. If it is determined No in S808, flg_ctrl is set to -1 in S810. flg_ctrl is output to the command correction means 702.

  When S808 is Yes, the alternating torque is changing from the positive side to the negative side. When S808 is No, the alternating torque is changing from the negative side to the positive side. By changing the direction of action of the alternating torque between positive and negative, the direction of the force acting on each mechanical part of the VTCl 13 that has been engaged so far is changed, and rattling occurs in each mechanical part. Not only the spiral radial link type variable valve mechanism shown in the present embodiment but also other mechanisms having a mechanical assembly portion similarly cause such mechanical backlash.

  Next, an example of backlash between the vortex groove 315 and the engagement pin 316 is shown as an example of how the mechanical play occurs and its influence and effect (the backlash is between the engagement pin 316 and the link 311 and between the link 311 and its fixed end. However, it will be explained). FIG. 10A is a diagram in which the backlash between the vortex groove 315 and the engagement pin 316 is emphasized, and FIG. 10B shows the alternating torque at each timing. In FIG. 10A (i), the alternating torque is applied to the positive side. At this time, the counterclockwise torque in the figure is applied to the protrusion 309 that rotates integrally with the camshaft 134 by the alternating torque. Due to this torque, a force that pushes the engagement pin 316 upward through the pin 312 and the link 311 acts. At this time, a control command is input to the vortex groove counterclockwise so that the VTCl 13 resists the force pushing up the engagement pin 316, and the phase is maintained by the balance of the force. At this time, the vortex groove 315 and the engagement pin 316 are engaged with each other on the upper side (upper side) of the engagement pin 316 in the drawing. As shown in the figure, play is generated between the lower side (lower side) of the engaging pin 316 and the vortex groove 315.

  When the alternating torque becomes zero at the timing (ii) in FIG. 10B, the aforementioned force acting on the engagement pin 316 becomes zero. Next, at the timing of (iii), the alternating torque changes to the negative side. At this time, contrary to the case of (i), a clockwise torque acts on the protrusion 309, and therefore, a force to push down the engaging pin 316 acts on the engaging pin 316. At this time, as shown in FIG. 10 (iii), there is a play on the lower side (downward) of the groove 315 and the engagement pin 316 due to the tolerance of each mechanical component. As described above, when the above-described push-up force or push-down force is applied in the presence of play, the vortex groove 315 and the engagement pin 316 collide vigorously, and a hitting sound or breakage occurs.

  The gist of the present invention is not the control in the absence of backlash as in the prior art, but the control is performed to reduce backlash in the presence of backlash. FIG. 11A shows the VTCl 13 at the timing (ii) in FIG. FIG. 11B shows an enlarged view of the broken line part of FIG.

  As shown in FIG. 11B, when the vortex groove 315 is located at the position θzu0 (one-dot chain line), backlash occurs between the engagement pin 316 and the vortex groove 315 as described above. Therefore, the correction control command Va (see FIG. 7) is input to the operation force applying means 305 to rotate the vortex disk 318 (see FIG. 2), and the vortex groove 315 is indicated by θzu0 shown by the solid line in FIG. From the position (dashed line) to the position of θuuz_CTRL. Thereby, the play between the vortex groove 315 and the engagement pin 316 can be closed (eliminated). By this operation, there is an advantage that it is possible to avoid a force from being applied in the presence of play, and to suppress a hitting sound and damage to the mechanism.

  Next, the main characteristics of the control device for the variable valve mechanism according to the embodiment of the present invention will be described qualitatively with reference to FIG. FIG. 17A shows that when the cam torque (alternating torque) is on the positive side, the cam torque acts as a force for pulling the engagement pin upward, and the VTC torque acts as shown by the arrow to They are balanced and the VTC phase is maintained. On the other hand, FIG. 17 (c) shows that when the cam torque (alternating torque) becomes negative, the cam torque acts as a force for pulling down the engagement pin. The mating pin will move downward in the vortex groove.

  In the process of shifting from the state of FIG. 17 (a) to the state of (c), as shown in FIG. 17 (b), the timing at which the cam torque crosses 0 is detected. The polarity of the torque (negative side) is predicted, and the vortex disk is rotated as shown in FIG. 17B so that the engagement pin does not move in the backlash portion. Then, the lower side of the engagement pin comes into contact with the lower edge of the vortex groove due to the reduced diameter of the vortex disk. That is, when the cam torque crosses zero, the vortex disk is moved so that the engagement pin is picked up so that the lower side of the engagement pin contacts the lower edge of the vortex groove. As a result, as shown in the lower view of FIG. 17 (c), even if the negative cam torque exerts a force to pull the engagement pin downward, the VTC to the engagement focus and the vortex disk is packed with looseness. The phase is balanced with the torque.

  The command correction unit 702 sets the correction control command Va based on flg_ctrl and maintains Va for a predetermined time Tth. This operation will be described with reference to the flowchart of FIG.

  First, in S1201, it is determined whether flg_ctrl is not 0 (see FIG. 8). If it is determined Yes in S1201, the timer Tva is reset to 0 in S1202. In S1203, the direction of the correction command Va is determined by Equation 2.

flg_ctrl> 0? ... Formula 2
If YES is determined in S1203, VR (described later) is set in provisional correction command Vtmp in S1204. If it is determined No in S1203, VA is set in the provisional correction command Vtmp in S1205. Then, the process proceeds to S1208. VR and VA are the magnitudes of correction commands set in advance by experiments or the like. VR is for generating an operating force in the positive direction, and VA is for generating an operating force in the negative direction.

  If it is determined No in S1201, the timer Tva is counted up every calculation cycle Tstep in S1206, the previous correction command Va is stored in Vtmp in S1207, and the process proceeds to S1208.

  In S1208, it is determined whether or not the timer Tva has reached Tth (see FIG. 13C, which will be described later) (for example, whether or not 50 times of a calculation cycle of 10 ms have elapsed by the timer). ). If it is determined Yes in S1208, the correction command Va has not been continued for a predetermined time, so the temporary correction command Vtmp is set in the correction command Va in S1209. If it is determined No in S1208, the correction command is after a predetermined time, so 0 is set to Va in S1210. Tth is a duration determined in advance by an experiment or the like. If the response of the actuator is slow, the required actuation force may not be obtained within the computation execution cycle. Therefore, a reliable operating force can be ensured by continuing the correction command for a time required for the actuator to exert the necessary operating force.

  The operation described above will be described with reference to the timing chart shown in FIG. This timing chart shows the alternating torque acting on the camshaft 134 (FIG. 13A), the output CAM of the cam sensor 132 (FIG. 13B), the correction command Va (FIG. 13C), and the actuation force based on the correction command. (FIG. 13D) shows the relationship between the phases of VTCl 13 (FIG. 13E). As can be seen from this timing chart, the alternating torque acts periodically. In VTCl13, the correction command Va takes a value other than 0 near the timing when the alternating torque becomes 0. As a result, the corrected operating force (FIG. 13D) is generated by Va, and the operating force is applied to the VTCl 13 in a direction in which there is no backlash.

  When the control command is made constant (when the correction operating force is not added to the constant value of the control command), it shows a vibrational behavior as shown by 13e2 in FIG. In particular, in the section indicated by the arrow in FIG. 13 (e), there is play, and the phase changes at high speed until the play is clogged. For this reason, the fluctuation width of the phase is large, and there is a possibility that a hitting sound or breakage occurs when the play is clogged.

  By applying the operating force so as to suppress the play as described above, it is possible to close the play before the force is applied to the mechanism by the alternating torque as in 13e2. As a result, the phase fluctuation width can be reduced. Further, in the state where there is a backlash, the force cannot be transmitted between the mechanical parts. However, by actively closing backlash as in the present invention, the response time of the actuator can be improved by the time required for backlash. Furthermore, since the play is stuffed, the hitting sound and damage can be suppressed.

  In the present embodiment, the alternating torque is used as an example of the torque acting on the camshaft 134, but the present invention is not limited to this. The present invention is effective for general torque fluctuations acting on the camshaft 134 in general. Periodic torque fluctuations acting on the camshaft 134 include, for example, engine equipment driven by the camshaft 134.

  FIG. 14 is a diagram illustrating a circuit configuration in which a control input to the VTC 113 according to the present embodiment is applied through the duty control unit 1401. FIG. 14 is different from FIG. 7 in that the control input ((Vff + Vfb) + Va) to the controlled object has a constant amplitude level in the duty control unit 1401 according to the magnitude, and the length of the on period and the off period ( The pulse width is controlled and applied to the VTC 113. Incidentally, in FIG. 7, the amplitude level of the control input is changed and applied to the VTC 113.

  In the above description, the basic technical idea of the control device for the variable valve mechanism according to the embodiment of the present invention is mainly described, but a more specific configuration will be described below. First, the basic technical idea of the present invention will be described. In the present invention, the fluctuation torque of the camshaft (camshaft), that is, the timing at which the alternating torque component is switched to the positive side or the negative side (the cam torque is By changing the operating state of the actuator so that an instantaneous (short-time) operating force against the alternating torque is applied to the variable valve mechanism at the timing immediately before (crossing zero)) The purpose is to control the rotational phase with a high degree of accuracy by eliminating the influence of torque fluctuation caused by the mechanical backlash of the mechanism.

  The control device for the variable valve mechanism according to the present embodiment described above is implemented when the engine speed Ne (obtained based on the crank speed, which is an output from the crank angle sensor) is a predetermined number or less, If the engine speed exceeds a predetermined number, a phenomenon occurs in which a movable member such as a link of the variable valve mechanism becomes physically and mechanically inoperable, so it is excluded from control (i.e., outputting a correction control command). Ban). In addition, although the engine speed is such that a movable member such as a link can move physically and mechanically, if the response of the actuator (the operating speed of the electromagnetic actuator for rotating the vortex disk) is not in time, the object of control It is outside. That is, an instantaneous (short time) operating force is applied to the variable valve mechanism only when the period of the alternating torque cycle is equal to or less than the engine speed at which the response time of the actuator is longer.

  In addition, the control device according to the present embodiment takes an example of a drive member and a camshaft (shaft member 307 integrated with a camshaft) as an example by rotating an intermediate rotating body as an example of a vortex disk. It can be applied to the one that changes the relative rotational phase of the driven member. Further, the control device of the present embodiment includes a spiral radial link type variable valve mechanism (an intermediate rotating body having a guide for reducing the diameter, a movable guide portion that is guided and engaged with the guide, a link that is swingably connected, and the like. It is applicable to what is provided. Furthermore, the actuator as the operating force applying means can be applied to an electromagnetic actuator that mechanically transmits an operating force to an intermediate rotating body (for example, a vortex disk).

  Further, when the temperature of the engine or the variable valve mechanism is below a predetermined value, the viscosity of the lubricating oil becomes high and the machine element does not move. Therefore, an instantaneous operating force is applied to the variable valve mechanism (or a correction control command). Is controlled to be prohibited.

  Further, since the cam torque magnitude τcam is uniquely determined by the camshaft rotation angle θcam (see the map in FIG. 9), the operating state of the actuator is changed so as to give an instantaneous operating force (FIG. 17B). The timing of moving the vortex disk shown in FIG. 9) may be obtained based on the detection of θcam using the map of FIG. 9 to determine the time point at which τcam = 0. The detection results from the cam angle detection means and the crank angle detection means that can detect the above may be used. Specifically, the cam torque is calculated using the sensor output from the cam sensor that outputs the cam signal at the reference rotation position, and the crank angle sensor that outputs the POS signal every 10 ° while outputting the reference crank signal at the reference rotation position. The timing of 0 is obtained (see FIG. 6), and the actuator is operated at this timing.

  In the above description, the timing for applying the correction operating force shown in FIG. 13D is when the alternating torque crosses the 0 level, but is corrected immediately before the alternating torque is switched from positive to negative or vice versa. Control to output operating force. That is, the operation state of the actuator is changed so that the operation of the variable valve mechanism is completed at the timing of crossing zero. By adopting such a timing, when the alternating torque whose phase is reversed in the vertical direction in FIG. 17 is applied to the engagement pin, the play is in a packed state. Since there is a slight time lag in the rotating operation of the vortex disk, the correction operating force is applied in advance including the time lag.

  Next, a configuration example when the duty control unit 1401 is employed in the control device for the variable valve mechanism of the present embodiment shown in FIG. 14 will be described below. First, the basic technical idea is to control the duty so that the actuator operates in the direction opposite to the direction of the camshaft alternating torque during the timing when the direction of the alternating torque changes from positive to negative or vice versa. To do. In the control device that does not perform duty control as shown in FIG. 7, command correction signals are generated at the levels of VR and VA over the period of Tth as shown in FIG. 13C, and (Vff + Vfd) value Are also added to the VTC. At this time, the duty is changed so that the actuator is operated when the period of one cycle of the alternating torque is equal to or less than the engine speed at which the time is shorter than half the duty of the duty control unit. In other words, when the engine speed is so high that the duty control by the duty control unit does not work effectively, the control of the present embodiment is not performed, which is useful for power saving.

  The duty control is performed by changing the pulse width of the duty, and this pulse width is controlled to vary depending on the engine speed or the engine temperature. For example, the pulse width is set when the engine speed is high. If it is made variable, the vortex disk can be rotated with a strong force, for example, and the play can be quickly packed. Instead of changing the duty pulse width, the pulse height may be changed, and the same effect as the pulse width is obtained. The height of the duty pulse may be varied depending on the engine temperature (ambient temperature of the variable valve mechanism) in addition to being varied depending on the engine speed. When the temperature is low, the viscosity of the lubricating oil increases. The pulse height is increased in order to apply a greater force (the width or height of the duty pulse may be varied by detecting the lubricating oil temperature).

  Further, in the case of a structure in which the load of the variable valve mechanism varies depending on the operating position (for example, when the phase θ forms large and small in FIG. 15, that is, the angle formed by the link is large and small). The force applied to the follower (engagement pin) is different), the height of the pulse is varied according to its operating position (when the phase θ is small, a large force is applied as the applied force) To increase the pulse height). Further, when the temperature of the engine is below a predetermined value, the duty control is prohibited so that the actuator is operated, so that the operation of each mechanism element in which the viscosity of the lubricating oil is increased is not required.

  Next, other configuration examples in the control device for the variable valve mechanism according to the embodiment of the present invention will be listed. That is, a drive member that receives rotation from a crankshaft, a driven member that is connected to a camshaft on which an alternating torque from a valve spring acts, and that receives rotational force from the drive member, the drive member, and the driven member A phase changing member that changes a relative rotational phase of the camshaft and an actuator that applies an operating force to the phase changing member according to an operating state, and the alternating torque component of the camshaft is switched to a positive side or a negative side. At or before the timing, the operating state of the actuator is changed so that an instantaneous operating force opposite to the alternating torque is applied to the phase changing member, and the phase changing member is interposed between the driving member and the driven member. By moving the interposed intermediate member, the relative rotational phase of the driving member and the driven member is changed. The valve timing control device made is to have an internal combustion engine.

  In the valve timing control device (VTC) for the internal combustion engine, the phase changing member is provided so as to be relatively rotatable with respect to the driving member and the driven member, and is provided on a surface facing the radial guide. An intermediate member having a guide that is reduced in diameter along the rotation direction, a movable guide portion that is guided and engaged with the guide so as to be displaceable, a portion that is separated from the rotation center of one of the drive member and the driven member, and A link that connects the movable guide unit so as to be swingable, and the intermediate member is rotated relative to the drive member and the driven member by the actuator, whereby the movable guide unit is displaced in the radial direction. The configuration is such that the assembly angle of the drive member and the driven member is changed. Furthermore, the actuator is an electromagnetic actuator that mechanically transmits an operating force to the intermediate member.

  Further, the controller is a VTC controller for an internal combustion engine that duty-controls an actuator that applies an operating force to a phase change member that changes a valve opening / closing timing in accordance with the state of the internal combustion engine, and an urging force of a valve spring acting on the camshaft. The duty is changed so that the actuator operates in the direction opposite to the direction of the alternating torque of the camshaft between the timings when the direction of is switched, and the period of the period of the alternating torque is ½ period of the duty. The duty is changed so that the actuator is operated in the direction opposite to the direction of operation of the alternating torque of the camshaft only when the rotational speed is shorter than the time.

  In addition, in a controller of a valve timing control device (VTC) for an internal combustion engine, a duty pulse width or a duty pulse that is changed so that the actuator operates in a direction opposite to the direction of the alternating torque of the camshaft depending on a predetermined condition. As an example, the height or width is variable depending on the rotational speed of the internal combustion engine or the temperature of the internal combustion engine.

It is a block diagram of the internal combustion engine of the vehicle carrying the control apparatus of the variable valve mechanism based on embodiment of this invention. It is sectional drawing which shows the internal structure of the variable valve mechanism to which the control apparatus which concerns on this embodiment is applied. FIG. 3 is a cross-sectional view showing a cross section taken along the line AA of FIG. 2 and showing an assembly angle operation mechanism in the variable valve mechanism. FIG. 3 is a cross-sectional view showing a hysteresis brake in the variable valve mechanism, showing a cross section taken along line BB in FIG. 2. It is a figure which shows the arrangement structure of the cam shaft of an engine, a cam, a valve spring, and an intake valve. It is a figure which shows the relationship between the camshaft rotation angle and fluctuation torque (cam torque) in a 4-cylinder engine. It is a control block diagram at the time of applying the control apparatus concerning this embodiment to a variable valve mechanism (VTC). It is a flowchart which shows the determination procedure of the torque fluctuation | variation determination means in the control apparatus which concerns on this embodiment. It is the figure which mapped so that the alternating torque of a camshaft might change depending on a camshaft rotation angle. It is explanatory drawing showing the action direction of the mechanical backlash and cam torque in the spiral radial link type variable valve mechanism regarding this embodiment. It is a figure which shows the structure for closing the mechanical backlash in the variable valve mechanism regarding this embodiment. It is a flowchart which shows the correction | amendment procedure of the instruction | command correction | amendment means in the control apparatus which concerns on this embodiment. It is a timing chart showing the control aspect in the control apparatus of the variable valve mechanism based on embodiment of this invention. A duty control unit is provided on the control input side to the variable valve mechanism according to this embodiment. It is explanatory drawing showing the phase fluctuation resulting from the mechanical backlash in the variable valve mechanism regarding this embodiment. It is explanatory drawing showing the influence on generation | occurrence | production of the cam fluctuation torque (cam torque) in a 4-cylinder engine, and a VTC phase. It is explanatory drawing showing the control timing and control structure of the mechanical backlash filling in the variable valve mechanism regarding this embodiment. It is explanatory drawing showing the output signal from a cam angle sensor and a crank angle sensor.

Explanation of symbols

101 ... Internal combustion engine
105 ... Intake valve 113 ... Variable valve mechanism (VTC)
114 ... Engine control unit (ECU)
117 ... Crank angle sensor 120 ... Crankshaft 132 ... Cam sensor 134 ... Intake side camshaft (camshaft)
302 ... Timing sprocket 304 ... Assembly angle operating mechanism 305 ... Operating force applying means (actuator)
308: Radial groove 309 ... Projection 311 ... Link 315 ... Vortex groove 316 ... Engagement pin 318 ... Vortex disk 320 ... Hysteresis brake 501 ... Cam 502 ... Valve spring 701 ... Torque fluctuation judging means 702 ... Command correcting means Ne ... Engine Rotational speed Qa ... Intake pipe flow rate Va ... Correction control command Tva ... Timer

Claims (12)

A drive member to which rotation is transmitted from the crankshaft, a driven member connected to a camshaft to which an alternating torque is applied and a rotational force is transmitted from the drive member, and a relative rotation phase between the drive member and the driven member is changed. A control device for controlling a variable valve mechanism comprising a phase change member, an actuation force applying member that applies actuation force to the phase change member,
The control device detects the timing at which the alternating torque of the camshaft is switched to the positive side or the negative side,
A control device for a variable valve mechanism that outputs a correction control command for applying a short-time operating force against the alternating torque immediately after the detected timing to the phase change member. A drive member to which rotation is transmitted from the crankshaft, a driven member connected to a camshaft to which an alternating torque is applied and a rotational force is transmitted from the drive member, and a relative rotation phase between the drive member and the driven member is changed. A control device for controlling a variable valve mechanism comprising a phase change member, an actuation force applying member that applies actuation force to the phase change member,
The control device detects a timing immediately before the alternating torque of the camshaft is switched to the positive side or the negative side,
A control device for a variable valve mechanism, which outputs a correction control command for applying a short-time operating force against the alternating torque after switching at the timing immediately before the detection to the phase change member. In claim 2,
The immediately preceding timing is determined so that the timing at which the operation of the phase changing member is ended by the operating force matches the timing at which the alternating torque of the camshaft is switched to the positive side or the negative side. Control device for the mechanism. A drive member to which rotation is transmitted from the crankshaft, a driven member connected to a camshaft to which an alternating torque is applied and a rotational force is transmitted from the drive member, and a relative rotation phase between the drive member and the driven member is changed. A control device for controlling a variable valve mechanism comprising a phase change member, an actuation force applying member that applies actuation force to the phase change member,
The control device includes a torque fluctuation determination unit that determines a timing at which the alternating torque is switched to a positive side or a negative side based on a cam angle of a cam provided on the camshaft and a crank angle of the crankshaft;
A command correction means for outputting a correction control command for generating a short-time operating force against the alternating torque immediately after the determined timing to the operating force applying member;
The control apparatus of the variable valve mechanism characterized by including. In claim 1 or 2,
The detection of the timing when the alternating torque switches to the positive side or the negative side, or the detection of the timing immediately before the alternating torque switches to the positive side or the negative side is detected from a cam angle sensor of a cam provided on the camshaft. A control apparatus for a variable valve mechanism, which is performed based on an output and a map showing a relationship between a cam angle and the alternating torque. In claim 1 or 2,
The detection of the timing at which the alternating torque switches to the positive side or the negative side, or the detection of the timing immediately before the alternating torque switches to the positive side or the negative side is performed by a cam shaft by a cam angle sensor of the cam provided on the cam shaft. A control apparatus for a variable valve mechanism, which is performed based on detection of a reference rotational position and a crank angle signal of the crankshaft. In claim 1 or 2,
Output of the correction control command is prohibited when a crank speed obtained from a crank angle sensor of the crankshaft exceeds a predetermined value, or when an ambient temperature of the variable valve mechanism is equal to or lower than a predetermined value. Control device for variable valve mechanism. In claim 1 or 2,
The control apparatus has a duty control unit that changes duty according to a control input including the correction control command on an input side of an operating force applying member that applies an operating force to the phase changing member. Control device for valve mechanism. In claim 8,
The duty control unit changes the width of the duty pulse or the height of the duty pulse. In claim 8,
The duty pulse width or the height of the duty pulse is varied according to a crank speed from a crank angle sensor of the crankshaft, an ambient temperature of the variable valve mechanism, or a lubricating oil temperature. Control device for the mechanism. In claim 8,
The control apparatus for a variable valve mechanism, wherein the height of the duty pulse is varied according to the operation position of the phase change member having a different operation load depending on the operation position.   An internal combustion engine comprising the control device for a variable valve mechanism according to any one of claims 1 to 11.

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