JP3793664B2 - Valve timing control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve timing control device for an internal combustion engine, and more particularly to a valve timing control device configured to continuously and variably control the rotation phase of a camshaft with respect to a crankshaft by hydraulic control using a valve.
[0002]
[Prior art]
Conventionally, there has been a vane type valve timing control device as disclosed in Japanese Patent Laid-Open No. 10-141022, as a valve timing control device having such a configuration.
[0003]
In this case, a recess is formed on the inner peripheral surface of a cylindrical housing fixed to the cam sprocket, while a vane of a impeller fixed to the camshaft is accommodated in the recess, The camshaft can be rotated relative to the cam sprocket within a range in which the wing portion can move.
[0004]
And the said wing | blade part hold | maintains the said wing | blade part in the intermediate position of the said recessed part by supplying and discharging oil relatively with respect to a pair of hydraulic chamber formed by dividing the said recessed part into the front and back of a rotation direction. Therefore, when the hydraulic pressure in the pair of hydraulic chambers is adjusted to the hydraulic pressure at which a target rotational phase can be obtained, the hydraulic passage is closed by a valve to supply oil. It was configured to stop evacuation.
[0005]
[Problems to be solved by the invention]
By the way, positive and negative rotational torque (hereinafter referred to as cam torque) is alternately generated in the camshaft by a valve spring that urges the intake / exhaust valve in the closing direction, and the hydraulic passage is closed by the valve to supply and discharge oil. When stopped, the hydraulic pressure in the hydraulic chamber on the side where the positive cam torque is applied increases. If oil leakage occurs due to an increase in hydraulic pressure due to the cam torque, when the cam torque is reversed, the air is sucked from the place where the oil leakage has occurred, and the oil in the sealed hydraulic path is air- When the cam torque is applied in a state where air is mixed, the compression ratio of air is larger than that of oil, so that when the positive cam torque is applied, the rotational phase is displaced more greatly. Rotation phase hunting may occur.
[0006]
The present invention has been made in view of the above problems, and in a valve timing control device for an internal combustion engine configured to continuously and variably control the rotational phase of a camshaft with respect to a crankshaft by hydraulic control by a valve, the rotational phase is determined by cam torque. An object is to prevent large hunting.
[0007]
[Means for Solving the Problems]
Therefore, the invention according to claim 1 is a valve timing control device for an internal combustion engine in which the rotational phase of the camshaft with respect to the crankshaft is continuously variable by controlling oil supply / discharge in the hydraulic chamber by a hydraulic control valve. Then, in a valve timing control device for an internal combustion engine that feedback-controls the control signal of the hydraulic control valve based on the measured value of the rotational phase, the control signal is forcibly changed when the feedback control is substantially converged. Thus, the oil is supplied and discharged in the hydraulic chamber.
[0008]
According to this configuration, feedback control is performed to supply and discharge oil in the hydraulic chamber in order to eliminate the rotational phase shift. When the feedback control returns to the vicinity of the target (when the feedback control is substantially converged), the control signal is forced. Change.
Accordingly, even when the target relative rotation position (rotation phase) does not change, the oil is not supplied and discharged, and the oil can be supplied and discharged.
[0009]
The invention according to claim 2 is characterized in that the oil is periodically supplied and discharged in the hydraulic chamber by causing a periodic fluctuation in the vicinity of the target of the rotational phase.
[0010]
According to such a configuration , oil is not supplied or discharged even when the relative rotation position (rotation phase) of the target does not change by causing periodic fluctuations within a narrow range near the target. The oil is always supplied and discharged.
[0011]
According to a third aspect of the present invention , when the control signal falls within a predetermined range , a predetermined offset amount is added to the control signal.
[0012]
According to such a configuration, by adding an offset amount to the control signal of the valve, the hydraulic pressure deviates from a value corresponding to the target rotational phase, and when this actually deviates, the feedback control is performed to return to the target rotational phase. The oil is discharged from the hydraulic chamber to which oil is supplied by adding the offset amount, and the oil is supplied to the hydraulic chamber from which oil is discharged by adding the offset amount. If the offset is added again when the control signal returns within the predetermined range as the signal converges, setting of the deviation from the target and elimination of the deviation are repeated.
[0013]
According to a fourth aspect of the invention, the predetermined range includes a signal range corresponding to the hydraulic pressure holding state.
According to this configuration, when returning to the control signal range that closes the hydraulic passage (stops oil supply / discharge), an offset is always added and the hydraulic passage is kept closed. There is no.
[0014]
According to a fifth aspect of the present invention, the offset amount is variably set according to the target value of the rotational phase.
According to this configuration, the volume of the hydraulic chamber at that time can be estimated from the target value of the rotation phase at that time, and the offset amount corresponding to the difference in sensitivity due to the volume can be obtained by setting the offset amount according to the volume. Will be set.
[0015]
In the invention described in claim 6, the offset amount is variably set according to the temperature of the hydraulic oil.
According to this configuration, the offset amount corresponding to the difference in sensitivity due to the temperature of the hydraulic oil, that is, the viscosity is set.
[0016]
In the invention according to claim 7, the temperature of the hydraulic oil is estimated based on the coolant temperature of the engine.
According to this configuration, instead of directly detecting the temperature of the hydraulic oil, the temperature of the hydraulic oil is estimated based on the coolant temperature correlated with the temperature of the hydraulic oil.
[0017]
The invention according to claim 8 is configured such that the offset amount is variably set according to the rotational speed of the internal combustion engine.
According to this configuration, in the case of the configuration using the cam torque variation due to the rotational speed and the engine-driven oil pump, the offset amount is set according to the variation of the supply oil.
[0018]
The invention according to claim 9 is configured such that the offset amount is variably set according to the supply pressure of the hydraulic oil.
According to such a configuration, the offset amount is set corresponding to the difference in the sensitivity of the pressure change in the hydraulic chamber due to the magnitude of the hydraulic oil supply pressure.
[0019]
According to a tenth aspect of the present invention, the camshaft is rotated relative to the cam sprocket to continuously and variably control the rotational phase of the camshaft with respect to the crankshaft. A pair of hydraulic chambers formed on a predetermined circumference on one side of the camshaft and provided on the other side of the camshaft and the cam sprocket and housed in the recess and partitioning the recess in the front and rear in the rotational direction. The rotational phase is continuously variably controlled by relatively supplying and discharging oil to and from the pair of hydraulic chambers.
[0020]
According to such a configuration, in a so-called vane type valve timing control device that continuously and variably controls the rotation phase by supplying and discharging oil relative to a pair of hydraulic chambers configured by the recess and the vane, Force oil supply and discharge to the hydraulic chamber to avoid holding the hydraulic passage in a sealed state.
[0021]
【The invention's effect】
According to the first aspect of the present invention, even when the target relative rotational position (rotation phase) does not change, it is possible to prevent the oil from being supplied and discharged, so that the cam torque acts. Even in this case, it is possible to prevent air from being sucked into the hydraulic path, thereby preventing the occurrence of rotational phase hunting.
[0022]
According to the second aspect of the present invention, oil is always supplied to and discharged from the hydraulic chamber to avoid a state where the hydraulic passage is sealed, so that air is sucked into the hydraulic passage even when cam torque is applied. Therefore, there is an effect that the occurrence of hunting of the rotational phase can be prevented.
[0023]
According to the third and fourth aspects of the present invention, forcible rotational phase shift is caused by the addition of the offset amount, and offset is added again according to the convergence of the shift, so that the hydraulic control valve is centered on the neutral point. Therefore, it is possible to prevent the occurrence of a steady deviation due to the addition of an offset.
[0024]
According to the fifth aspect of the present invention, there is an effect that it is possible to avoid an excessive change in rotational phase while giving an optimum offset amount according to the volume of the hydraulic chamber and preventing air from being sucked.
[0025]
According to the sixth aspect of the present invention, there is an effect that it is possible to avoid an excessive change in the rotational phase while giving an optimum offset amount according to the viscosity of the hydraulic oil and preventing air from being sucked.
[0026]
According to the seventh aspect of the present invention, by estimating the temperature of the hydraulic oil from the coolant temperature, it is possible to accurately detect the temperature of the hydraulic oil even in a specification in which it is difficult to attach a sensor that directly detects the temperature of the hydraulic oil. In addition, there is an effect that the cost can be reduced by eliminating the need for a sensor that directly detects the temperature of the hydraulic oil.
[0027]
According to the eighth aspect of the present invention, it is possible to provide an optimum offset amount corresponding to a difference in cam torque due to the rotational speed of the engine and a difference in the amount of oil supplied from the pump, thereby preventing the intake of air. However, there is an effect that an excessive change in the rotational phase can be avoided.
[0028]
According to the ninth aspect of the invention, there is an effect that it is possible to avoid an excessive change in rotational phase while giving an optimum offset amount corresponding to the supply pressure of oil to the hydraulic chamber and preventing air from being sucked.
[0029]
According to the invention described in claim 10, in the so-called vane type valve timing control device, it is possible to prevent air from being sucked into the hydraulic path even if cam torque is applied, thereby preventing the occurrence of hunting of the rotational phase. effective.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIGS. 1-6 shows the mechanism part of the valve timing control apparatus of the internal combustion engine in embodiment, and shows what was applied to the intake valve side.
[0031]
The valve timing control device shown in the figure is provided so as to be rotatable relative to the cam sprocket 1 (timing sprocket) that is rotationally driven via a timing chain by an engine crankshaft (not shown). Camshaft 2, rotating member 3 fixed to the end of camshaft 2 and rotatably accommodated in cam sprocket 1, and hydraulic circuit for rotating the rotating member 3 relative to cam sprocket 1 4 and a lock mechanism 10 that selectively locks the relative rotational position of the cam sprocket 1 and the rotating member 3 at a predetermined position.
[0032]
The cam sprocket 1 includes a rotating portion 5 having a tooth portion 5a meshing with a timing chain (or timing belt) on the outer periphery, and a housing 6 disposed in front of the rotating portion 5 and rotatably accommodating the rotating member 3. A disc-shaped front cover 7 serving as a lid for closing the front end opening of the housing 6, and a substantially disc-shaped rear cover disposed between the housing 6 and the rotating portion 5 to close the rear end of the housing 6. 8, and the rotating portion 5, the housing 6, the front cover 7, and the rear cover 8 are integrally coupled from the axial direction by four small-diameter bolts 9.
[0033]
The rotating portion 5 has a substantially annular shape, and has four female screw holes 5b through which the small-diameter bolts 9 are screwed in the circumferentially equidistant positions of about 90 ° in the front-rear direction. A step-diameter fitting hole 11 into which a passage-forming sleeve 25 described later is fitted is formed through. Further, a disc-shaped fitting groove 12 into which the rear cover 8 is fitted is formed on the front end surface.
[0034]
The housing 6 has a cylindrical shape in which both front and rear ends are formed with openings, and four partition walls 13 project from the circumferential position of the inner peripheral surface at 90 °. The partition wall 13 has a trapezoidal shape in cross section, is provided along the axial direction of the housing 6, and both end edges are flush with the both end edges of the housing 6. Four bolt insertion holes 14 through which the small-diameter bolts 9 are inserted are formed penetrating in the axial direction. Further, a U-shaped seal member 15 and a leaf spring 16 that presses the seal member 15 inward are fitted into a holding groove 13a that is cut out along the axial direction at the center position of the inner end face of each partition wall 13. Is retained.
[0035]
Further, the front cover 7 has a relatively large-diameter bolt insertion hole 17 at the center, and four bolt holes 18 at positions corresponding to the bolt insertion holes 14 of the housing 6. ing.
[0036]
The rear cover 8 has a disc portion 8a fitted and held in the fitting groove 12 of the rotating member 5 on the rear end surface, and a small-diameter annular portion 25a of the sleeve 25 is fitted in the center. A fitting hole 8c is formed, and four bolt holes 19 are also formed at positions corresponding to the bolt insertion holes 14.
[0037]
The camshaft 2 is rotatably supported at the upper end portion of the cylinder head 22 via a cam bearing 23, and a cam (not shown) for opening the intake valve via a valve lifter is integrated at a predetermined position on the outer peripheral surface. In addition, a flange portion 24 is integrally provided at the front end portion.
[0038]
The rotating member 3 is fixed to the front end portion of the camshaft 2 by a fixing bolt 26 inserted from the axial direction through the sleeve 25 whose front and rear portions are fitted in the flange portion 24 and the fitting hole 11, respectively. An annular base portion 27 having a bolt insertion hole 27a through which the fixing bolt 26 is inserted, and four vanes 28a, 28b, 28c, 28d integrally provided at 90 ° positions in the circumferential direction of the outer peripheral surface of the base portion 27; It has.
[0039]
Each of the first to fourth vanes 28a to 28d has a substantially inverted trapezoidal cross section, and is disposed in a recess between the partition walls 13, and separates the recess in the front and rear in the rotation direction. An advance side hydraulic chamber 32 and a retard side hydraulic chamber 33 are formed between both sides and both side surfaces of each partition wall portion 13. In addition, a U-shaped seal member 30 slidably contacting the inner peripheral surface 6a of the housing 6 and the seal member 30 are pressed outwardly into a holding groove 29 cut in the axial direction at the center of the outer peripheral surface of each of the vanes 28a to 28d. The leaf springs 31 are fitted and held.
[0040]
The lock mechanism 10 is formed through an engagement groove 20 formed at a predetermined position on the outer peripheral side of the fitting groove 12 of the rotating portion 5 and a predetermined position of the rear cover 8 corresponding to the engagement groove 20. An engagement hole 21 whose inner peripheral surface is tapered, a sliding hole 35 formed through the substantially central position of the one vane 28 corresponding to the engagement hole 21 along the internal axis direction, and the one A lock pin 34 slidably provided in the sliding hole 35 of the vane 28, a coil spring 39 that is a spring member elastically mounted on the rear end side of the lock pin 34, and the lock pin 34 and the sliding hole 35 is formed with a pressure receiving chamber 40 formed between them.
[0041]
The lock pin 34 includes a middle-side main body 34a on the center side, an engaging portion 34b formed in a substantially tapered shape on the front end side of the main body 34a, and a large step formed on the rear end side of the main body 34a. The engaging hole 21 is formed by the spring force of the coil spring 39 elastically mounted between the bottom surface of the internal concave groove 34d of the stopper portion 34c and the inner end surface of the front cover 7. And the hydraulic pressure in the pressure receiving chamber 40 formed between the outer peripheral surface between the main body 34a and the stopper portion 34c and the inner peripheral surface of the sliding hole 35. It slides in the direction of coming out of the engagement hole 21. The pressure receiving chamber 40 communicates with the retard angle side hydraulic chamber 33 through a through hole 36 formed in a side portion of the vane 28. Further, the engaging portion 34 b of the lock pin 34 is configured such that the engaging portion 34 b is engaged with the engaging hole 21 at the rotation position on the maximum retard angle side of the rotating member 3.
[0042]
The hydraulic circuit 4 includes two systems, a first hydraulic passage 41 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 32 and a second hydraulic passage 42 that supplies and discharges hydraulic pressure to the retard side hydraulic chamber 33. The hydraulic passages 41 and 42 are connected to a supply passage 43 and a drain passage 44 through passage-switching electromagnetic switching valves 45, respectively. The supply passage 43 is provided with an oil pump 47 that pumps the oil in the oil pan 46, while the downstream end of the drain passage 44 communicates with the oil pan 46.
[0043]
The first hydraulic passage 41 is branched and formed in the head portion 26a from the cylinder head 22 through the first passage portion 41a formed in the axial center of the camshaft 2 and the axial direction in the fixing bolt 26. A first oil passage 41b that communicates with the first passage portion 41a, a small-diameter outer peripheral surface of the head portion 26a, and an inner peripheral surface of the bolt insertion hole 27a that is provided in the base portion 27 of the rotating member 3 are the first. An oil chamber 41c that communicates with the oil passage 41b, and four branch passages 41d that are formed substantially radially in the base portion 27 of the rotating member 3 and communicate with the oil chamber 41c and each advance-side hydraulic chamber 32. Yes.
[0044]
On the other hand, the second hydraulic passage 42 is bent into a substantially L shape inside the cylinder head 22 and the second passage portion 42a formed inside the camshaft 2 and the inside of the sleeve 25. A second oil passage 42b communicating with the passage portion 42a, four oil passage grooves 42c formed at the outer peripheral side hole edge of the fitting hole 11 of the rotating member 5 and communicating with the second oil passage 42b, and the periphery of the rear cover 8. The four oil holes 42 d are formed at positions of about 90 ° in the direction and communicate with each oil passage groove 42 c and the retard side hydraulic chamber 33.
[0045]
The electromagnetic switching valve 45 is configured such that an internal spool valve body switches and controls each of the hydraulic passages 41 and 42, the supply passage 43, and the drain passages 44a and 44b, and a control signal from the controller 48. It is designed to be switched by.
[0046]
Specifically, as shown in FIGS. 4 to 6, a cylindrical valve body 51 inserted and fixed in the holding hole 50 of the cylinder block 49 and a valve hole 52 in the valve body 51 are slidable. The spool valve body 53 is provided to switch the flow path, and a proportional solenoid type electromagnetic actuator 54 that operates the spool valve body 53.
[0047]
The valve body 51 is formed with a supply port 55 penetrating the downstream end of the supply passage 43 and the valve hole 52 at a substantially central position of the peripheral wall, and the first and the second on both sides of the supply port 55. A first port 56 and a second port 57 that communicate with the other end of the second hydraulic passages 41 and 42 and the valve hole 52 are formed penetratingly. Further, third and fourth ports 58 and 59 are formed through both ends of the peripheral wall so as to communicate the drain passages 44a and 44b with the valve hole 52.
[0048]
The spool valve body 53 has a substantially cylindrical first valve portion 60 that opens and closes the supply port 55 at the center of the small diameter shaft portion, and opens and closes the third and fourth ports 58 and 59 at both ends. It has substantially cylindrical second and third valve portions 61 and 62. The spool valve body 53 is a conical valve spring 63 elastically mounted between an umbrella portion 53b provided at one end edge of the support shaft 53a on the front end side and a spring seat 51a provided on the inner peripheral wall of the front end side of the valve hole 52. Therefore, the supply valve 55 and the second hydraulic passage 42 are urged in the right direction in FIG.
[0049]
The electromagnetic actuator 54 includes a core 64, a moving plunger 65, a coil 66, a connector 67, and the like, and a driving rod 65 a that presses the umbrella portion 53 b of the spool valve body 53 is fixed to the tip of the moving plunger 65.
[0050]
The controller 48 detects the current operating state (load, rotation) based on signals from the rotation sensor 101 that detects the engine rotation speed and the air flow meter 102 that detects the intake air amount, and from the crank angle sensor 103 and the cam sensor 104. The relative rotation position of the cam sprocket 1 and the camshaft 2, that is, the rotational phase of the camshaft 2 with respect to the crankshaft is detected by the above signal.
[0051]
The controller 48 controls the energization amount to the electromagnetic actuator 54 based on a duty control signal on which a dither signal is superimposed.
For example, when a control signal (OFF signal) with a duty ratio of 0% is output from the controller 48 to the electromagnetic actuator 54, the spool valve body 53 moves to the position shown in FIG. . As a result, the first valve portion 60 opens the open end 55a of the supply port 55 to communicate with the second port 57, and at the same time, the second valve portion 61 opens the open end of the third port 58, and the fourth The valve part 62 closes the fourth port 59. Therefore, the hydraulic oil pressure-fed from the oil pump 47 is supplied to the retarded hydraulic chamber 33 through the supply port 55, the valve hole 52, the second port 57, and the second hydraulic passage 42, and at the advanced side. The hydraulic oil in the hydraulic chamber 32 is discharged from the first drain passage 44a into the oil pan 46 through the first hydraulic passage 41, the first port 56, the valve hole 52, and the third port 58.
[0052]
Therefore, the internal pressure of the retard side hydraulic chamber 33 is high and the internal pressure of the advance side hydraulic chamber 32 is low, and the rotating member 3 rotates in one direction at the maximum via the vanes 28a to 28b. As a result, the cam sprocket 1 and the camshaft 2 rotate relative to one side to change the phase. As a result, the opening timing of the intake valve is delayed and the overlap with the exhaust valve is reduced.
[0053]
On the other hand, when a control signal (ON signal) with a duty ratio of 100% is output from the controller 48 to the electromagnetic actuator 54, the spool valve element 53 is maximally leftward against the spring force of the valve spring 63 as shown in FIG. At the same time as the third valve portion 61 closes the third port 58 by sliding, the fourth valve portion 62 opens the fourth port 59, and the first valve portion 60 includes the supply port 55 and the first port 56. To communicate with. Therefore, the hydraulic oil is supplied into the advance side hydraulic chamber 32 through the supply port 55, the first port 56, and the first hydraulic passage 41, and the hydraulic oil in the retard side hydraulic chamber 33 is second. The oil is discharged to the oil pan 46 through the hydraulic passage 42, the second port 57, the fourth port 59, and the second drain passage 44b, and the retard side hydraulic chamber 33 becomes low pressure.
[0054]
For this reason, the rotating member 3 rotates to the maximum in the other direction via the vanes 28a to 28d, whereby the cam sprocket 1 and the camshaft 2 are relatively rotated to the other side and the phase is changed. The opening timing of the intake valve is advanced (advanced), and the overlap with the exhaust valve is increased.
[0055]
The controller 48 has a position in which the first valve portion 60 closes the supply port 55, the third valve portion 61 closes the third port 58, and the fourth valve portion 62 closes the fourth port 59. The relative duty position (rotation phase) between the cam sprocket 1 and the camshaft 2 detected based on signals from the crank angle sensor 103 and the cam sensor 104, while the base duty ratio BASEDTY (for example, 50%) is used. ) And the target value (target advance value) of the relative rotation position (rotation phase) set according to the driving state is set by a proportional / integral / derivative (PID) operation. The final duty ratio VTCDTY is obtained by adding the base duty ratio BASEDTY and the feedback correction amount PIDDTY. The control signal of the duty ratio VTCDTY are to be output to the electromagnetic actuator 54.
[0056]
That is, when it is necessary to change the relative rotation position (rotation phase) in the retarding direction, the duty ratio is reduced by the feedback correction amount PIDDTY, and the hydraulic oil fed from the oil pump 47 is retarded. While being supplied to the hydraulic chamber 33, the hydraulic oil in the advance side hydraulic chamber 32 is discharged into the oil pan 46. Conversely, the relative rotation position (rotation phase) is changed in the advance direction. If it is necessary to increase the duty ratio, the duty ratio is increased by the feedback correction amount PIDDTY, the hydraulic oil is supplied into the advance hydraulic chamber 32, and the hydraulic oil in the retard hydraulic chamber 33 is supplied to the oil pan 46. Will be discharged. When the relative rotation position (rotation phase) is maintained in the current state, the absolute value of the feedback correction amount PIDDTY is decreased, so that the duty ratio is controlled to return to the vicinity of the base duty ratio. The internal pressures of the hydraulic chambers 32 and 33 are controlled by closing the 55, the third port 58, and the fourth port 59 (stopping the supply and discharge of hydraulic pressure).
[0057]
FIG. 7 is a block diagram showing how the controller 48 controls the duty of the electromagnetic actuator 54.
As shown in FIG. 7, while an addition value of the base duty ratio BASEDTY and the feedback correction amount PIDDTY is obtained, a duty ratio obtained by adding a predetermined offset amount to the addition value is calculated, and a duty not adding an offset amount is calculated. One of the ratio and the duty ratio to which the offset amount is added is selectively output.
[0058]
As shown in the figure, the base duty ratio BASEDTY is such that the supply port 55, the third port 58, and the fourth port 59 are all closed, and no oil is supplied or discharged in any of the hydraulic chambers 32 and 33. It is set to the approximate median of the range.
[0059]
When the value obtained by adding the feedback correction amount PIDDTY to the base duty ratio BASEDTY is within a predetermined range (VDTRL # <BASEDTY + PIDDTY <VDTRH #), specifically, the oil supply / discharge of oil in any of the hydraulic chambers 32 and 33 is performed. Including the duty ratio range in which the offset is not performed, and addition of an offset is selected when it is within a range slightly wider than the duty ratio range, and the relative rotation position (rotation phase) is added by adding the offset. In order to eliminate the deviation, feedback control is performed to supply and discharge oil in the hydraulic chamber. When the feedback control returns to the vicinity of the target (when the feedback control substantially converges), an offset is added again. As a result, periodic fluctuations are generated within a narrow range near the target. That.
[0060]
As a result, even when the target relative rotational position (rotation phase) does not change, the supply port 55, the third port 58, and the fourth port 59 are all closed, and the oil supply in any of the hydraulic chambers 32 and 33 is performed. Oil is not always discharged and is always supplied and discharged.
[0061]
When the supply port 55, the third port 58, and the fourth port 59 are closed and no cam oil is supplied or discharged in any of the hydraulic chambers 32 and 33, the hydraulic chamber to which positive torque is applied is applied. When the negative pressure is applied, there is a possibility that air is sucked from the leaked portion, and the amplitude due to the cam torque being added by the suction of air increases, As a result, the relative rotation position (rotation phase) is greatly hunted.
[0062]
On the other hand, if the oil is always supplied and discharged as described above, it is possible to prevent the air from being sucked in, thereby preventing the occurrence of hunting due to the air sucking.
[0063]
By the way, the offset amount is desired to be a value that causes the shift of the relative rotation position (rotation phase) to be as small as possible. Therefore, the offset amount is set variably according to the operating conditions.
[0064]
In the present embodiment, the basic value VDTYOF for the offset is calculated based on the target value (target advance value) VTCangle of the relative rotation position (rotation phase) and the engine coolant temperature Tw detected by the water temperature sensor 105. Further, the basic value VDTYOF is corrected with a correction coefficient corresponding to the engine speed.
[0065]
The target value VTCangle is a parameter indicating the volume of the hydraulic chambers 32 and 33. The larger the volume, the less sensitive the pressure change to the hydraulic control. Therefore, the offset amount is variably set according to the target value VTCangle. It is.
[0066]
The coolant temperature Tw is used as a temperature that correlates with the temperature of the hydraulic oil. Further, the temperature of the hydraulic oil is a parameter that correlates with the viscosity of the hydraulic oil, and the difference in sensitivity due to the difference in the viscosity of the oil. Corresponding to the above, the offset amount is variably set. In addition, it is good also as a structure which detects the temperature of hydraulic fluid directly, and sets the basic value VDTYOF using the detection result.
[0067]
Furthermore, the engine speed is a parameter that correlates with the magnitude of the cam torque and that correlates with the amount of hydraulic oil supplied by the oil pump, and is corrected to an appropriate offset amount in accordance with these conditions. .
[0068]
Here, the supply pressure of hydraulic oil from the oil pump may be detected by a pressure sensor, and the offset amount may be variably set based on the supply pressure. The supply pressure is a parameter that correlates with the sensitivity of pressure change caused by hydraulic control, as with the amount of oil supplied.
[0069]
The offset amount may be a plus (advance direction) value or a minus (retard direction) value.
The flowchart of FIG. 8 shows the control function shown in FIG. 7. In S1, the target advance value is calculated, in S2, the actual advance value is detected, and in S3, the dither signal is superimposed. To calculate a feedback correction amount PIDDTY.
[0070]
In S4, the calculation of the offset amount is variably set according to the target advance value, the water temperature (oil temperature), the engine speed, and the like.
In S5, it is determined whether or not the added value of the base duty ratio BASEDTY and the feedback correction amount PIDDTY is within a predetermined range, and when it is not within the predetermined range, that is, without adding an offset amount, When the supply / discharge condition is satisfied, the offset amount is reset to 0 in S6, and if it is within the predetermined range, the calculation result of the offset amount in S4 is held as it is, and the process proceeds to S7.
[0071]
In S7, an added value of the base duty ratio BASEDTY, the feedback correction amount PIDDTY, and the offset amount VDTYOF is obtained, and a final control duty is determined by adding a correction according to the power supply voltage to the added value.
[0072]
In the above embodiment, the valve timing control device is a so-called vane type. However, a mechanism for causing the hydraulic pressure in the hydraulic chamber to act in the axial direction of the camshaft and converting the hydraulic pressure in the axial direction into a rotational force is provided. A valve timing control device configured to continuously change the rotational phase by controlling the hydraulic pressure in the hydraulic chamber to a pressure corresponding to a target advance value by supplying and discharging hydraulic pressure to and from the hydraulic chamber; In order to constantly supply and discharge the hydraulic pressure in the hydraulic chamber, an offset may be added each time the hydraulic feedback control substantially converges.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a valve timing control mechanism in an embodiment.
2 is a cross-sectional view taken along the line BB in FIG.
FIG. 3 is an exploded perspective view of the valve timing control mechanism.
FIG. 4 is a longitudinal sectional view showing an electromagnetic switching valve in the valve timing control mechanism.
FIG. 5 is a longitudinal sectional view showing an electromagnetic switching valve in the valve timing control mechanism.
FIG. 6 is a longitudinal sectional view showing an electromagnetic switching valve in the valve timing control mechanism.
FIG. 7 is a control block diagram of the valve timing control mechanism.
FIG. 8 is a flowchart showing the control content of the valve timing control mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cam sprocket 2 ... Cam shaft 3 ... Rotating member 4 ... Hydraulic circuit 6 ... Housing 7 ... Front cover 13 ... Partition 28a-28d ... Vane 32 ... Advance side hydraulic chamber 33 ... Delay side hydraulic chamber 45 ... Electromagnetic switching valve 47 ... Oil pump 51 ... Valve body 52 ... Valve hole 53 ... Spool valve body 55 ... Supply port 55a ... Open end 56 ... First port 57 ... Second port 60 ... First valve portion 101 ... Rotation sensor 102 ... Air flow meter 103 ... Crank angle sensor 104 ... Cam sensor 105 ... Water temperature sensor

Claims (10)

A valve timing control device for an internal combustion engine that continuously varies a rotational phase of a camshaft with respect to a crankshaft by controlling oil supply and discharge in a hydraulic chamber by a hydraulic control valve, wherein the rotational phase measurement value is In a valve timing control device for an internal combustion engine that performs feedback control of a control signal of the hydraulic control valve based on
A valve timing control apparatus for an internal combustion engine, wherein when the feedback control is substantially converged, the control signal is forcibly changed to supply and discharge oil in the hydraulic chamber. 2. The valve timing control device for an internal combustion engine according to claim 1, wherein the supply and discharge of oil in the hydraulic chamber is periodically performed by causing periodic fluctuations in the vicinity of the target of the rotational phase. 3. The valve timing control device for an internal combustion engine according to claim 1 , wherein a predetermined offset amount is added to the control signal when the control signal falls within a predetermined range . The valve timing control device for an internal combustion engine according to claim 3, wherein the predetermined range includes a signal range corresponding to a hydraulic pressure maintaining state. 5. The valve timing control device for an internal combustion engine according to claim 3 , wherein the offset amount is variably set according to a target value of the rotational phase. The valve timing control device for an internal combustion engine according to any one of claims 3 to 5 , wherein the offset amount is variably set according to the temperature of the hydraulic oil. 7. The valve timing control device for an internal combustion engine according to claim 6, wherein the temperature of the hydraulic oil is estimated based on a coolant temperature of the engine. The valve timing control device for an internal combustion engine according to any one of claims 3 to 7 , wherein the offset amount is variably set according to a rotational speed of the internal combustion engine. The valve timing control device for an internal combustion engine according to any one of claims 3 to 8 , wherein the offset amount is variably set according to a supply pressure of the hydraulic oil. The camshaft is rotated relative to the cam sprocket to continuously variably control the rotational phase of the camshaft with respect to the crankshaft, on a predetermined circumference on one side of the camshaft and the cam sprocket. And a vane that is provided on the other side of the camshaft and the cam sprocket and that is accommodated in the recess and divides the recess in the front and rear in the rotational direction to form a pair of hydraulic chambers, 10. The internal combustion engine according to claim 1, wherein the rotational phase is continuously variably controlled by relatively supplying and discharging oil to and from the pair of hydraulic chambers. Valve timing control device.

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