JP3714056B2 - Valve characteristic control method and control apparatus for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve characteristic control method and control apparatus for an internal combustion engine, and more specifically, at least one of an intake valve and an exhaust valve is supplementarily provided separately from opening and closing of a main intake / exhaust valve that determines output characteristics and the like of the engine. The present invention relates to a control method and a control device for controlling an EGR (exhaust gas recirculation) amount or the like in a combustion chamber of the engine by opening the valve.
[0002]
[Prior art]
As is well known, there is EGR (exhaust gas recirculation) control for returning a part of exhaust gas to intake air as a method for reducing nitrogen oxide (NOx) in the exhaust gas. As a method for returning a part of the exhaust gas to the intake air, a method of opening the exhaust valve in the intake stroke or auxiliary opening the intake valve in the exhaust stroke has been conventionally known.
[0003]
As a device for performing so-called internal EGR control based on this method, for example, in Japanese Patent Laid-Open No. 10-89033, an auxiliary cam crest is provided behind the main cam crest constituting the main portion of the exhaust cam, and the auxiliary cam crest is provided. The cam crest height is formed so as to continuously change from one end of the camshaft to the other end, and the camshaft is opened according to the operating state of the engine while opening the exhaust valve in the intake stroke. It is described that the lift amount can be adjusted by displacing in the axial direction. According to this configuration, when the exhaust valve is auxiliary opened in the intake stroke, the lift amount is continuously variable, so that not only the EGR is secured but also the EGR amount can be adjusted. .
[0004]
[Problems to be solved by the invention]
By the way, since the exhaust pressure is not always constant and pulsates, there is no linear correspondence between the change in the lift amount of the exhaust valve and the change in the EGR amount in the intake stroke. Absent. Therefore, the EGR amount may not increase with the lift amount increased, or conversely, the EGR amount may increase rapidly as the lift amount increases.
[0005]
For this reason, when the auxiliary opening of the exhaust valve is performed in a region where the exhaust pressure is high, for example, for the purpose of increasing the dynamic range (control range) of EGR control, there is a concern that the control accuracy of the EGR amount itself may be reduced. Become so. On the other hand, when the auxiliary opening of the exhaust valve is performed in a region where the exhaust pressure is low for the purpose of controlling the EGR amount with high accuracy, the control width, that is, the dynamic range may be lowered. Therefore, just because the EGR amount can be adjusted just as in the above-described conventional device, both the control of the EGR amount with high accuracy and the control with a high dynamic range over the entire operation range of the engine are achieved. Has become extremely difficult.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is an internal combustion engine capable of achieving both high-precision control and control in a high dynamic range with respect to the internal EGR amount of the engine. The object is to provide a valve characteristic control method and a control device.
[0007]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, the intake valve and the exhaust valve are connected to each other based on the auxiliary opening of at least one of the intake valve and the exhaust valve separately from the opening and closing of the main intake and exhaust valves that determine the output characteristics of the internal combustion engine. In the valve characteristic control method for an internal combustion engine that controls the exhaust gas recirculation amount inside the combustion chamber of the engine by generating a period during which the valve is simultaneously opened, the auxiliary valve opening by at least one of the intake valve and the exhaust valve is opened. Valve timing When the required exhaust gas recirculation amount is large, the exhaust gas pressure is set at a higher timing than when the exhaust gas recirculation amount is small. This is the gist.
[0008]
As described above, the exhaust pressure is not always constant but pulsates. In addition, the change of the exhaust pressure depends on the operating state of the engine. For example, it is possible to estimate the exhaust pressure from each stroke of the engine and the rotation angle of the engine output shaft in those strokes. For this reason, if the opening timing of the auxiliary valve opening is set, for example, at the timing when the exhaust pressure becomes high, according to the pulsation of the exhaust pressure as in the above control method, the engine combustion has a high dynamic range. If it becomes possible to control the exhaust gas recirculation amount in the interior and conversely set the opening timing of the auxiliary valve at the timing when the exhaust pressure decreases, the combustion chamber of the engine is highly accurate. It becomes possible to control the exhaust gas recirculation amount. Therefore, according to the exhaust gas recirculation amount required in each operation region of the engine and the control request (dynamic range or accuracy), the auxiliary valve opening is considered while considering the pulsation of the exhaust pressure. If the start time is variably set, it is possible to achieve both control requests. In this case, (a) when the required exhaust gas recirculation amount is large, the auxiliary valve opening start timing is set to a timing at which the exhaust pressure is high, and when the required exhaust gas recirculation amount is small, the auxiliary auxiliary valve opening timing is set. By setting the start timing of the valve opening to a timing when the exhaust pressure is low, control that satisfies the required amount of exhaust gas recirculation over the entire operating range of the engine, or It is easy to realize fine adjustment control according to the pulsation of the exhaust pressure when the flow rate needs to be increased or decreased.
[0009]
According to the second aspect of the present invention, the cam that drives at least one of the intake valve and the exhaust valve is in the same period during a period other than the valve opening period of the main cam peak in addition to the main cam peak that mainly opens the valve. The auxiliary cam crest has a period during which the intake valve and the exhaust valve are opened simultaneously by performing auxiliary valve opening, and the height of the auxiliary cam crest is continuous in the axial direction of the cam. A valve operating mechanism formed as a three-dimensional cam that changes into a valve, and a variable valve lift mechanism that adjusts a valve lift amount by the auxiliary cam crest by displacing a cam shaft provided with the cam in the axial direction thereof. ,Previous The opening timing of the valve to be opened and closed by the auxiliary cam crest When the required exhaust gas recirculation amount is large, the exhaust gas pressure is set at a higher timing than when the exhaust gas recirculation amount is small. The gist of the present invention is to provide valve opening timing variable means.
[0010]
According to the above configuration, Since the valve lift amount by the auxiliary cam crest is adjusted by the valve lift amount variable mechanism, and the valve opening timing of the valve to be opened / closed by the auxiliary cam crest is set by the valve opening time varying means, An apparatus for accurately realizing the method of the first aspect of the invention can be easily configured.
[0011]
According to a third aspect of the present invention, in the second aspect of the present invention, the valve opening timing varying means can vary the relative rotational phase between the output shaft of the engine and the camshaft provided with the valve operating means. The gist of the invention is that it comprises a variable valve timing mechanism.
[0012]
According to the said structure, in the apparatus of Claim 2, the valve opening start timing variable means can be easily implement | achieved using the existing means, such as a valve timing variable means.
[0013]
The gist of the invention according to claim 4 is that the valve timing variable mechanism is operated in advance according to the exhaust pressure of the engine.
According to the above configuration, the method described in claim 1 can be accurately realized in the apparatus described in claim 2.
[0014]
According to a fifth aspect of the present invention, in the second aspect of the present invention, the valve opening timing varying means is such that the apex of the auxiliary cam crest is continuously different in height from the cam shaft in the cam shaft direction. The gist is that it consists of a three-dimensional bias cam profile of the auxiliary cam mountain continuously biased in the direction.
[0015]
According to the above configuration, the auxiliary valve opening timing by the auxiliary cam peak considering the pulsation of the exhaust pressure described above can be realized through the three-dimensional bias cam profile of the auxiliary cam peak. Therefore, the valve opening timing varying means can be configured without using the valve timing varying mechanism, and the device according to claim 2 can be simplified. Further, according to this configuration, the main valve characteristic due to the main cam crest is not changed.
[0016]
According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the vertices of the auxiliary cam crest having different heights continuously in the cam shaft direction are biased in a direction gradually increasing backward in the rotation direction of the cam. The gist of this is
[0017]
According to the above configuration, as the apex of the auxiliary cam peak increases, the valve opening timing of the valve by the auxiliary cam peak shifts to the retard side. Therefore, for example, if the deviation mode of the auxiliary cam peak is set corresponding to a period in which the exhaust pressure gradually increases, when the valve opening amount by the auxiliary cam peak is small, the valve is opened at a timing when the exhaust pressure is small. Therefore, the exhaust gas recirculation amount can be controlled with high accuracy. Further, when the valve opening amount by the auxiliary cam crest is large, the valve can be opened at a timing when the exhaust pressure is large, and a high dynamic range can be obtained. On the other hand, if the deviation mode of the auxiliary cam crest is set corresponding to a period in which the exhaust pressure gradually decreases, when the valve opening amount by the auxiliary cam crest is small, the valve is opened at a timing when the exhaust pressure is large. Therefore, the exhaust gas recirculation amount can be rapidly increased at the start of the control of the exhaust gas recirculation amount. Further, when the valve opening amount by the auxiliary cam crest is large, the valve can be opened at a timing when the exhaust pressure is small, and the exhaust gas recirculation amount can be controlled with high precision control. Therefore, it is possible to quickly respond to the start of exhaust gas recirculation control while maintaining accuracy when the required exhaust gas recirculation amount is large.
[0018]
According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the apexes of the auxiliary cam crest that are continuously different in height in the cam shaft direction are biased in a direction that gradually increases forward in the rotational direction of the cam. The gist of this is
[0019]
According to the said structure, the valve opening time by an auxiliary cam peak can be shifted to an advance side, so that the vertex of an auxiliary cam peak becomes high. Therefore, for example, if the deviation mode of the auxiliary cam peak is set corresponding to a period in which the exhaust pressure gradually decreases, when the valve opening amount by the auxiliary cam peak is small, the valve is opened at a timing when the exhaust pressure is small. Therefore, the exhaust gas recirculation amount can be controlled with high accuracy. Further, when the valve opening amount by the auxiliary cam crest is large, the valve can be opened at a timing when the exhaust pressure is large, and a high dynamic range can be obtained. On the other hand, if the deviation mode of the auxiliary cam peak is set corresponding to a period in which the exhaust pressure gradually increases, when the valve opening amount by the auxiliary cam peak is small, the valve is opened at a timing when the exhaust pressure is large. Therefore, the exhaust gas recirculation amount can be rapidly increased at the start of the control of the exhaust gas recirculation amount. Further, when the valve opening amount by the auxiliary cam crest is large, the valve can be opened at a timing when the exhaust pressure is small, and the exhaust gas recirculation amount can be controlled with high precision control. Therefore, it is possible to quickly respond to the start of exhaust gas recirculation control while maintaining accuracy when the required exhaust gas recirculation amount is large.
[0020]
The invention described in claim 8 This is applied to an in-cylinder direct injection internal combustion engine in which fuel is directly injected into the combustion chamber, and the cam that drives the exhaust valve is opened by the main cam peak in addition to the main cam peak that mainly opens the valve. The auxiliary cam crest has an auxiliary cam crest that causes a period in which the intake valve and the exhaust valve are opened at the same time by performing auxiliary valve opening during a period other than the period. The valve operating means formed as a three-dimensional cam that continuously changes in the axial direction of the cam and the cam shaft provided with the cam are displaced in the axial direction to adjust the valve lift amount by the auxiliary cam crest. A variable valve lift mechanism, and a valve opening timing variable means for varying the valve opening timing for opening the exhaust valve through the auxiliary cam peak during the intake stroke of the engine in accordance with the fuel injection timing in the intake stroke. To prepare It Is the gist.
[0021]
2. Description of the Related Art Conventionally, a direct injection internal combustion engine that directly injects fuel into a combustion chamber in order to improve the fuel efficiency by increasing the degree of freedom of formation of an air-fuel mixture is known. However, the in-cylinder injection internal combustion engine has a problem in that the fuel is not sufficiently vaporized in the combustion chamber and the combustibility is easily hindered. In this respect, according to the above configuration, it is possible to variably control the timing of taking the exhaust gas into the combustion chamber based on the fuel injection timing, and it is possible to promote the vaporization of the fuel injected into the combustion chamber by the high-temperature exhaust gas. It becomes like this.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment of a valve characteristic control device according to the present invention provided for an intake side camshaft of an internal combustion engine (engine) will be described with reference to FIGS.
[0023]
FIG. 1 shows a schematic configuration centering on a valve operating system in an in-line four-cylinder on-vehicle gasoline engine 11 as an internal combustion engine. In the engine 11, the valve characteristic control device 10 is provided on the intake side camshaft 22.
[0024]
The engine 11 includes a cylinder block 13 provided with a reciprocating piston 12, an oil pan 13 a provided on the lower side of the cylinder block 13, and a cylinder head 14 provided on the upper side of the cylinder block 13. .
[0025]
A crankshaft 15 as an output shaft is rotatably supported at the lower part of the engine 11, and a piston 12 is connected to the crankshaft 15 via a connecting rod 16. The reciprocating movement of the piston 12 is converted into rotation of the crankshaft 15 by the connecting rod 16. A combustion chamber 17 is provided above the piston 12, and an intake port 18 and an exhaust port 19 are connected to the combustion chamber 17. The intake port 18 and the combustion chamber 17 are communicated and blocked by the intake valve 20, and the exhaust port 19 and the combustion chamber 17 are communicated and blocked by the exhaust valve 21.
[0026]
On the other hand, the intake side camshaft 22 and the exhaust side camshaft 23 are provided in the cylinder head 14 in parallel. The intake side camshaft 22 is supported on the cylinder head 14 so as to be rotatable and movable in the axial direction, and the exhaust side camshaft 23 is supported on the cylinder head 14 so as to be rotatable but not movable in the axial direction. Has been.
[0027]
One end of the intake side camshaft 22 includes a timing sprocket 24a, and a rotational phase difference variable actuator 24 (corresponding to a variable valve timing mechanism) for changing the rotational phase difference between the crankshaft 15 and the intake side camshaft 22. Is provided. Further, a variable lift amount actuator 22a (corresponding to a variable valve lift mechanism) for moving the intake camshaft 22 in the direction of the rotation axis is provided at the other end of the intake camshaft 22. A timing sprocket 25 is attached to one end of the exhaust side camshaft 23. The timing sprocket 25 and the timing sprocket 24a of the rotational phase difference variable actuator 24 are connected to a timing sprocket 15a attached to the crankshaft 15 via a timing chain 15b. Then, the rotation of the crankshaft 15 as the driving side rotating shaft is transmitted to the intake side camshaft 22 and the exhaust side camshaft 23 as the driven side rotating shaft via the timing chain 15b. As a result, the intake camshaft 22 and the exhaust camshaft 23 rotate in synchronization with the rotation of the crankshaft 15. In the example of FIG. 1, the crankshaft 15, the intake camshaft 22, and the exhaust camshaft 23 rotate clockwise (clockwise) when viewed from the timing sprockets 15a, 24a, and 25 side.
[0028]
The intake camshaft 22 is provided with an intake cam 27 that comes into contact with a valve lifter 20 a attached to the upper end of the intake valve 20, and the exhaust camshaft 23 contacts the valve lifter 21 a attached to the upper end of the exhaust valve 21. An exhaust cam 28 in contact therewith is provided. When the intake camshaft 22 rotates, the intake valve 20 is opened and closed by the intake cam 27, and when the exhaust camshaft 23 rotates, the exhaust valve 21 is opened and closed by the exhaust cam 28.
[0029]
Here, the exhaust cam 28 has a main cam crest that determines output characteristics of the engine 11, and the main cam crest is constant with respect to the axial direction of the exhaust side camshaft 23. On the other hand, the intake cam 27, as shown in FIG. 2, is used to open the intake valve 20 in an auxiliary manner independent of the main cam peak 27a and the main cam peak 27a, which determine the output characteristics of the engine 11, etc. And an auxiliary cam crest 27b. The apex of the auxiliary cam crest 27b continuously changes in the axial direction of the intake side camshaft 22. Thereby, the lift amount in the auxiliary valve opening of the intake valve 20 can be adjusted by displacing the intake side camshaft 22 in the axial direction by the lift amount variable actuator 22a.
[0030]
The rotational phase difference variable actuator 24 and the lift amount variable actuator 22a described above are controlled by an electronic control unit (hereinafter referred to as "ECU") 120. The ECU 120 is supplied with detection results from the intake pressure sensor 121 that measures the pressure in the intake pipe and the crank sensor 122 that measures the rotation speed of the engine 11 as electrical signals, and performs control based on these. .
[0031]
Next, the lift amount variable actuator 22a for moving the intake camshaft 22 in the axial direction and the oil supply structure for driving the lift amount variable actuator 22a by hydraulic pressure will be described with reference to FIG.
[0032]
As shown in FIG. 3, the lift amount variable actuator 22 a includes a cylindrical cylinder tube 31, a piston 32 provided in the cylinder tube 31, and a pair provided to close both end openings of the cylinder tube 31. End cover 33. The cylinder tube 31 is fixed to the cylinder head 14.
[0033]
The intake side camshaft 22 is connected to the piston 32 via an auxiliary shaft 33 a penetrating one end cover 33. A rolling bearing 33b is interposed between the auxiliary shaft 33a and the intake side camshaft 22, and the lift variable actuator 22a moves the rotating intake side camshaft 22 through the auxiliary shaft 33a and the rolling bearing 33b in the direction of the rotation axis. It can be driven smoothly.
[0034]
The cylinder tube 31 is partitioned into a first pressure chamber 31a and a second pressure chamber 31b by a piston 32. A first supply / discharge passage 34 formed in one end cover 33 is connected to the first pressure chamber 31a, and a second supply / discharge passage 35 formed in the other end cover 33 is connected to the second pressure chamber 31b. Is connected.
[0035]
When hydraulic fluid is selectively supplied to the first pressure chamber 31 a and the second pressure chamber 31 b via the first supply / discharge passage 34 or the second supply / discharge passage 35, the piston 32 rotates the intake camshaft 22. Move in the axial direction. As the piston 32 moves, the intake camshaft 22 also moves in the direction of the rotation axis.
[0036]
The first supply / discharge passage 34 and the second supply / discharge passage 35 are connected to a first oil control valve 36. A supply passage 37 and a discharge passage 38 are connected to the first oil control valve 36. The supply passage 37 is connected to the oil pan 13a via an oil pump P that is driven as the crankshaft 15 rotates, and the discharge passage 38 is directly connected to the oil pan 13a.
[0037]
The first oil control valve 36 includes a casing 39, and the casing 39 is provided with a first supply / discharge port 40, a second supply / discharge port 41, a first discharge port 42, a second discharge port 43, and a supply port 44. ing. A first supply / discharge passage 34 is connected to the first supply / discharge port 40, and a second supply / discharge passage 35 is connected to the second supply / discharge port 41. Further, a supply passage 37 is connected to the supply port 44, and a discharge passage 38 is connected to the first discharge port 42 and the second discharge port 43. In the casing 39, a spool 48 having four valve portions 45 and urged in opposite directions by a coil spring 46 and an electromagnetic solenoid 47 is provided.
[0038]
In the demagnetized state of the electromagnetic solenoid 47, the spool 48 is disposed on one end side (the right side in FIG. 3) of the casing 39 by the elastic force of the coil spring 46, and the first supply / discharge port 40 and the first discharge port 42 communicate with each other. The second supply / discharge port 41 and the supply port 44 communicate with each other. In this state, the hydraulic oil in the oil pan 13a is supplied to the first pressure chamber 31a through the supply passage 37, the first oil control valve 36, and the first supply / discharge passage 34. Further, the hydraulic oil that has been in the second pressure chamber 31b is returned to the oil pan 13a through the second supply / discharge passage 35, the first oil control valve 36, and the discharge passage 38. As a result, the piston 32 moves to the right side in the figure, and the intake side camshaft 22 moves in the direction R in the direction indicated by the arrow S in conjunction with the piston 32.
[0039]
On the other hand, when the electromagnetic solenoid 47 is energized, the spool 48 is disposed on the other end side (the left side in FIG. 3) of the casing 39 against the elastic force of the coil spring 46, and the second supply / discharge port 41 is the second. The first supply / discharge port 40 communicates with the supply port 44 in communication with the discharge port 43. In this state, the hydraulic oil in the oil pan 13a is supplied to the second pressure chamber 31b through the supply passage 37, the first oil control valve 36, and the second supply / discharge passage 35. Further, the hydraulic oil that has been in the first pressure chamber 31 a is returned to the oil pan 13 a through the first supply / discharge passage 34, the first oil control valve 36, and the discharge passage 38. As a result, the piston 32 moves to the left side in the drawing, and the intake camshaft 22 moves in the direction F in the direction indicated by the arrow S in conjunction with the piston 32.
[0040]
Further, when the power supply to the electromagnetic solenoid 47 is controlled and the spool 48 is positioned in the middle of the casing 39, the first supply / discharge port 40 and the second supply / discharge port 41 are closed. Movement of hydraulic fluid is prohibited. In this state, the hydraulic oil is not supplied to or discharged from the first pressure chamber 31a and the second pressure chamber 31b, and the hydraulic oil is filled and held in the first pressure chamber 31a and the second pressure chamber 31b. As a result, the positions of the piston 32 and the intake camshaft 22 in the rotation axis direction are fixed. The state shown in FIG. 6 represents this fixed position state.
[0041]
Further, by controlling the power supply to the electromagnetic solenoid 47, the opening degree in the first supply / discharge port 40 or the opening degree in the second supply / discharge port 41 is adjusted, and the first pressure chamber 31 a or the first pressure chamber is adjusted from the supply port 44. 2 The supply speed of hydraulic oil to the pressure chamber 31b can be controlled.
[0042]
Next, a rotation phase difference variable actuator (corresponding to a variable valve timing mechanism) 24 for adjusting the rotation phase difference of the intake camshaft 22 will be described in detail with reference to FIG.
[0043]
As shown in FIG. 4, the rotational phase difference variable actuator 24 includes a timing sprocket 24a. The timing sprocket 24a includes a cylindrical portion 51 through which the intake camshaft 22 passes, a disc portion 52 protruding from the outer peripheral surface of the cylindrical portion 51, and a plurality of external teeth 53 provided on the outer peripheral surface of the disc portion 52. It has. The cylindrical portion 51 of the timing sprocket 24a is sandwiched between the journal bearing 14a and the camshaft bearing cap 14b of the cylinder head 14 and is rotatably supported. The intake camshaft 22 penetrates the cylinder portion 51 so as to be able to slide and move in the cylinder portion 51 in the direction of the rotation axis.
[0044]
Further, an inner gear 54 provided so as to cover the distal end portion of the intake camshaft 22 is fixed by a bolt 55. As shown in FIG. 8, the inner gear 54 has a structure in which a large-diameter gear portion 54a having a flat tooth and a small-diameter gear portion 54b having an inclined tooth are formed in two stages.
[0045]
Further, the sub-gear 56 having the flat external teeth 56a and the oblique internal teeth 56b shown in FIG. 5 meshes with the small-diameter gear portion 54b of the inner gear 54 as shown in FIG. Has been. At the time of this engagement, a ring-shaped spring washer 57 is disposed between the inner gear 54 and the sub gear 56 and urges the sub gear 56 in the axial direction so as to be separated from the inner gear 54. The outer diameters of the inner gear 54 and the sub gear 56 are the same.
[0046]
The disc portion 52 of the timing sprocket 24 a is provided with a plurality of bolts 58 (here, four bolts), a housing 59, a first pressure chamber 70 and a second pressure chamber 71, which will be described later, within the housing 59. And a cover 60 for sealing the. At the center of the cover 60, a hole 60a is provided for opening a cylindrical space 61c, which will be described later, and smoothly sliding the intake camshaft 22 in the axial direction.
[0047]
FIG. 6 shows a state in which the bolt 58, the cover 60, and the bolt 55 are removed and the inside of the housing 59 is viewed from the left in FIG. Note that the rotational phase difference variable actuator 24 in FIG. 4 shows a cross-sectional state taken along line BB in FIG.
[0048]
As shown in FIG. 6, the housing 59 includes a plurality of wall portions 62, 63, 64, 65 (four in this case) that protrude from the inner peripheral surface 59 a toward the center. And the disk-shaped vane rotor 61 which contact | connects with the outer peripheral surface 61a with respect to the front end surface of the wall parts 62, 63, 64, 65 is arrange | positioned so that rotation is possible.
[0049]
A cylindrical space 61c (FIG. 4) is formed at the center of the disk-shaped vane rotor 61. Particularly in the present embodiment, the entire inner peripheral surface thereof extends along the axial direction of the intake camshaft 22. A spline portion 61b extending linearly is formed. Both the large-diameter gear portion 54a of the inner gear 54 and the external teeth 56a of the sub gear 56 are engaged with the spline portion 61b.
[0050]
Due to the engagement of the inclined inner teeth 56b and the inclined small diameter gear portion 54b and the action of the spring washer 57, the large diameter gear portion 54a of the inner gear 54 and the outer teeth 56a of the sub gear 56 are relatively opposite to each other. An urging force that rotates is generated. For this reason, the backlash between the spline part 61b and the gears 54 and 56 is absorbed, and the inner gear 54 can be arranged with high accuracy with respect to the vane rotor 61, and the hitting sound is also suppressed.
[0051]
Further, the disk-shaped vane rotor 61 protrudes into the space between the wall portions 62, 63, 64, 65 on the outer peripheral surface 61 a, and the vanes 66, 67, 67 are in contact with the inner peripheral surface 59 a of the housing 59. 68, 69. These vanes 66, 67, 68, 69 define a space between the walls 62, 63, 64, 65, thereby forming a first pressure chamber 70 and a second pressure chamber 71.
[0052]
In the configuration described above, when the crankshaft 15 is rotated by driving the engine 11, the rotation is transmitted to the timing sprocket 24a via the timing chain 15b. At this time, the timing sprocket 24a and the intake camshaft 22 rotate together in the adjusted rotational phase difference state. As the intake camshaft 22 rotates, the intake valve 20 (FIG. 1) is driven to open and close.
[0053]
When the engine 11 is driven, the vane rotor 61 is rotated relative to the housing 59 in the rotational direction by hydraulic control on the first pressure chamber 70 and the second pressure chamber 71. That is, if the rotational phase difference adjustment control is performed to the side where the intake side camshaft 22 is advanced with respect to the crankshaft 15, the entire operating angle of the intake valve 20 is advanced, and the opening / closing timing of the intake valve 20 is advanced.
[0054]
Conversely, the vane rotor 61 is rotated relative to the housing 59 in the direction opposite to the rotation direction. That is, if the adjustment control of the rotational phase difference is performed on the side where the intake side camshaft 22 is retarded with respect to the crankshaft 15, the entire operating angle of the intake valve 20 is retarded and the opening / closing timing of the intake valve 20 is delayed.
[0055]
Next, a configuration in which the rotational phase difference between the housing 59 and the vane rotor 61 is hydraulically controlled in the rotational phase difference variable actuator 24 in order to adjust the rotational phase difference of the intake side camshaft 22 will be described.
[0056]
As shown in FIGS. 4 and 6, the advance oil passage openings 80 are respectively opened on the first pressure chamber 70 side of the respective wall portions 62 to 65 projecting into the housing 59, and the respective wall portions 62. On the second pressure chamber 71 side of .about.65, retardation oil passage openings 81 are opened. Further, even if the vanes 66 to 69 block the advance oil passage opening 80 on the disk portion 52 side among the walls 62 to 65 in contact with the advance oil passage opening 80, the vane rotor 61. The recesses 62a to 65a are provided so that the hydraulic pressure that rotates in the advance direction can be applied. Similarly, even if the vanes 66 to 69 block the retarding oil passage opening 81 on the disk portion 52 side among the wall portions 62 to 65 in contact with the retarding oil passage opening 81, the vane rotor Recesses 62b to 65b are provided so that 61 can provide hydraulic pressure that rotates in the retarding direction.
[0057]
On the other hand, as shown in FIG. 4, each advance angle oil passage opening 80 is formed by the advance angle control oil passage 84 in the disc portion 52 and the advance angle control oil passages 86 and 88 in the tube portion 51. It is connected to one outer peripheral groove 51 a of the part 51. Also, each retarding oil passage opening 81 is connected to the other outer peripheral groove 51b of the cylindrical portion 51 by the retarding control oil passage 85 in the disc portion 52 and the retarding control oil passages 87 and 89 in the cylindrical portion 51. It is connected to the.
[0058]
Further, the lubricating oil passage 90 branched from the retard angle control oil passage 87 in the cylindrical portion 51 is connected to a wide inner peripheral groove 91 provided on the inner peripheral surface 51 c of the cylindrical portion 51. As a result, the hydraulic oil flowing in the retard angle control oil passage 87 is guided as lubricating oil to the inner peripheral surface 51 c of the cylinder portion 51 and the outer peripheral surface 22 b of the end portion of the intake side camshaft 22.
[0059]
One outer peripheral groove 51 a of the cylinder portion 51 is connected to the second oil control valve 94 via an advance angle control oil passage 92 in the cylinder head 14, and the other outer peripheral groove 51 b of the cylinder portion 51 is connected to the cylinder head 14. It is connected to the second oil control valve 94 via a retard angle control oil passage 93.
[0060]
A supply passage 95 and a discharge passage 96 are connected to the second oil control valve 94. The supply passage 95 is connected to the oil pan 13a through the same oil pump P used in the first oil control valve 36, and the discharge passage 96 is directly connected to the oil pan 13a. Therefore, the oil pump P is configured to send hydraulic oil from the oil pan 13a to the two supply passages 37 and 95.
[0061]
The second oil control valve 94 is configured in the same manner as the first oil control valve 36. That is, the second oil control valve 94 includes a casing 102, a first supply / discharge port 104, a second supply / discharge port 106, a valve portion 107, a first discharge port 108, a second discharge port 110, a supply port 112, and a coil spring 114. , An electromagnetic solenoid 116, and a spool 118. An advance angle control oil path 92 in the cylinder head 14 is connected to the first supply / discharge port 104, and a retard angle control oil path 93 in the cylinder head 14 is connected to the second supply / discharge port 106. A supply passage 95 is connected to the supply port 112, and a discharge passage 96 is connected to the first discharge port 108 and the second discharge port 110.
[0062]
Therefore, in the demagnetized state of the electromagnetic solenoid 116, the spool 118 is disposed on one end side (the right side in FIG. 4) of the casing 102 by the elastic force of the coil spring 114. Accordingly, the first supply / discharge port 104 and the first discharge port 108 communicate with each other, and the second supply / discharge port 106 communicates with the supply port 112. In this state, the hydraulic oil in the oil pan 13a is supplied to the supply passage 95, the second oil control valve 94, the retard control oil passage 93, the outer circumferential groove 51b, the retard control oil passage 89, the retard control oil passage 87, the retard control oil passage 87, The oil is supplied to the second pressure chamber 71 of the rotational phase difference variable actuator 24 via the angle control oil passage 85, the retard oil passage opening 81, and the recesses 62b, 63b, 64b, 65b. The hydraulic oil in the first pressure chamber 70 of the rotational phase difference variable actuator 24 includes the recesses 62a, 63a, 64a, 65a, the advance oil passage opening 80, the advance control oil passage 84, and the advance control. The oil is returned to the oil pan 13a through the oil passage 86, the advance angle control oil passage 88, the outer circumferential groove 51a, the advance angle control oil passage 92, the second oil control valve 94, and the discharge passage 96. As a result, the vane rotor 61 rotates relative to the housing 59 in the retarded direction, and the intake side camshaft 22 rotates relative to the crankshaft 15 in the retarded direction as described above.
[0063]
On the other hand, when the electromagnetic solenoid 116 is excited, the spool 118 is disposed on the other end side (left side in FIG. 4) of the casing 102 against the elastic force of the coil spring 114. Accordingly, the second supply / discharge port 106 communicates with the second discharge port 110, and the first supply / discharge port 104 communicates with the supply port 112. In this state, the hydraulic oil in the oil pan 13a is supplied to the supply passage 95, the second oil control valve 94, the advance angle control oil path 92, the outer circumferential groove 51a, the advance angle control oil path 88, the advance angle control oil path 86, the advance angle. The oil is supplied to the first pressure chamber 70 of the rotational phase difference variable actuator 24 through the angle control oil passage 84, the advance oil passage opening 80, and the recesses 62a, 63a, 64a, 65a. The hydraulic oil in the second pressure chamber 71 of the rotational phase difference variable actuator 24 includes the recesses 62b, 63b, 64b, 65b, the retard oil passage opening 81, the retard control oil passage 85, and the retard control. The oil is returned to the oil pan 13 a through the oil passage 87, the retard control oil passage 89, the outer circumferential groove 51 b, the retard control oil passage 93, the second oil control valve 94, and the discharge passage 96. As a result, the vane rotor 61 rotates relative to the housing 59 in the advance direction, and the intake side camshaft 22 rotates relative to the crankshaft 15 as described above.
[0064]
Further, when the power supply to the electromagnetic solenoid 116 is controlled and the spool 118 is positioned in the middle of the casing 102, the first supply / discharge port 104 and the second supply / discharge port 106 are closed, and the supply / discharge ports 104, 106 are connected. Movement of hydraulic fluid is prohibited. In this state, hydraulic fluid is not supplied to or discharged from the first pressure chamber 70 and the second pressure chamber 71 of the rotational phase difference variable actuator 24. As a result, hydraulic oil is filled and held in the first pressure chamber 70 and the second pressure chamber 71, and the vane rotor 61 stops rotating relative to the housing 59. Therefore, the rotational phase difference between the intake camshaft 22 and the crankshaft 15 is maintained in the state when the vane rotor 61 is fixed.
[0065]
In addition, the duty of power supply to the electromagnetic solenoid 116 is controlled to adjust the opening at the first supply / discharge port 104 or the opening at the second supply / discharge port 106, and the first pressure chamber 70 or the first pressure chamber 70 is adjusted from the supply port 112. 2 The hydraulic oil supply speed to the pressure chamber 71 can be controlled.
[0066]
Next, the valve characteristic control method according to the present embodiment will be described in detail with reference to FIG. 1, FIG. 7, and FIG.
In the present embodiment, the memory in the ECU 120 stores the above-described lift amount variable actuator 22a and the rotation phase difference variable from the value of the detection result (intake pipe pressure) of the intake pressure sensor 121 and the rotation speed obtained by the crank sensor 122. A two-dimensional map that defines the control amount of the actuator 24 is stored. The value of this two-dimensional map is supplied from the ECU 120 to the variable lift amount actuator 22a and the variable rotation phase difference actuator 24 as an operation command corresponding to the respective operating state of the engine 11, and mainly the above-described EGR (exhaust gas recirculation) control. Is done. That is, the auxiliary cam crest 27b of the intake cam 27 shown in FIG. 2 performs control to return a part of the exhaust gas to the intake air by opening the intake valve 20 auxiliary during the valve opening period of the exhaust valve 21. .
[0067]
Incidentally, as shown in FIG. 7, the pressure of the exhaust gas is not constant and constantly pulsates according to the operating state of the engine 11. That is, during the exhaust stroke, the exhaust pressure increases until it reaches a substantially maximum pressure value in the region a, and the pressure value is kept substantially constant between the region a and the region b. In the region b, the exhaust pressure decreases. Accordingly, even if the lift amount of the valve opening by the auxiliary cam crest 27b is the same, the amount of EGR that is taken in, and thus the EGR rate, also changes depending on the opening timing of the intake valve 20 by the auxiliary cam crest 27b.
[0068]
FIG. 8 shows the relationship between the center of opening of the intake valve 20 by the auxiliary cam crest 27 b (intake two-stage lift center) and the EGR rate taken into the combustion chamber 17. As shown in FIG. 8, when the center of the intake valve 20 is opened in the region a, the EGR rate that is taken in even with the same lift amount increases as the center position shifts to the retard side. . However, when the center of the opening of the intake valve 20 is in the region between the region a and the region b, it is taken in even if the center position is moved as expected from the exhaust pressure pulsation described above. The EGR rate is kept substantially constant.
[0069]
Therefore, in an operation region where the EGR rate required by the engine 11 is large, control for setting the valve opening timing of the intake valve 20 by the auxiliary cam crest 27b to the high EGR amount request region side shown in FIGS. 7 and 8 can be performed. preferable. On the other hand, when the auxiliary cam crest 27b is opened on the high EGR amount request region side shown in FIG. 8 in the operation region where the EGR rate required by the engine 11 is small, a slight increase in the lift amount causes a large increase in the EGR amount. Therefore, it may be difficult to control the EGR amount with high accuracy. Therefore, in an operation region where the EGR amount required by the engine 11 is small, it is preferable to perform control to set the valve opening timing of the intake valve 20 by the auxiliary cam crest 27b to the low EGR amount request region side shown in FIGS. .
[0070]
Note that, according to the lift center of FIG. 8 and the mode of increase / decrease of the EGR amount with respect to the lift amount, the change in the EGR amount (rate) with respect to the lift amount change is large, particularly in the high EGR amount request region of FIG. It can be seen that the characteristic is smaller when the lift amount is smaller than when the lift amount is smaller. Therefore, when the control with the lift amount increased is performed in the high EGR amount request region, the error of the taken-in EGR rate becomes smaller than the control with the lift amount decreased in the same region.
[0071]
In this embodiment, in view of these characteristics, the start timing of the opening of the auxiliary cam crest 27b is increased as shown in FIGS. The control advance angle value of the rotational phase difference variable actuator 24 described above is determined so as to shift to the EGR amount request area side.
[0072]
That is, when the required EGR rate is small, the opening timing of the intake valve 20 by the auxiliary cam crest 27b is set in the low EGR amount request region of FIGS. 7 and 8, and the lift amount variable actuator 22a is set in the region. By adjusting the lift amount, the EGR amount is controlled with high accuracy. On the other hand, when the required EGR rate is large, the opening timing of the intake valve 20 by the auxiliary cam crest 27b is set in the high EGR amount request region of FIGS. 7 and 8, and the lift amount variable actuator 22a is set in the region. By adjusting the lift amount, the EGR amount is controlled with a high dynamic range.
[0073]
As described above, according to the present embodiment, the following effects can be obtained.
(1) Aside from the main valve characteristics that determine the output characteristics and the like, the intake valve 20 is opened in an auxiliary manner, thereby assisting the intake valve 20 in controlling the EGR amount for taking in the EGR gas into the combustion chamber 17. By setting the appropriate valve opening timing based on the exhaust pressure, it is possible to perform optimal control according to the required EGR amount.
[0074]
(2) In the operation region where the EGR amount required by the engine 11 is large, the required EGR amount is reliably ensured by setting the valve opening timing of the intake valve 20 by the auxiliary cam crest 27b to a region where the exhaust pressure is high. be able to. On the other hand, in the operating region where the EGR amount required by the engine 11 is small, the opening timing of the intake valve 20 by the auxiliary cam crest 27b is set to a region where the exhaust pressure is low, so that the EGR amount can be controlled with high accuracy. . Further, when the control for increasing the lift amount is performed in the high EGR amount request region, the error tends to be relatively small, so that the EGR control with high accuracy and high dynamic range can be performed.
[0075]
(3) Auxiliary cam crest 27b provided independently of the main cam crest 27a, a lift amount variable actuator 22a that makes the lift amount of the intake valve 20 variable by the auxiliary cam crest 27b, and a valve opening timing of the intake valve 20 by the auxiliary cam crest By configuring the valve characteristic control device using the variable rotational phase difference actuator 24 that makes the variable variable, it is possible to relatively easily configure a device that can accurately obtain the effects (1) and (2). it can.
[0076]
Note that the valve characteristic control device of the first embodiment may be modified as follows.
In the above embodiment, as the engine 11 shifts to an operation region where a high EGR amount is required, the valve opening timing of the auxiliary cam crest 27b is set to shift to the higher exhaust pressure. When the increase / decrease correction of the EGR amount is performed according to the vehicle environment, such as traveling at high altitudes, the valve opening timing of the auxiliary cam crest 27b is further shifted to the side where the exhaust pressure is low and the side where the increase is high is the exhaust pressure. You may make it make it. By combining this control with the lift amount control, it is possible to perform EGR control with higher accuracy.
[0077]
In the above embodiment, the auxiliary cam crest 27b is provided in the intake cam 27, and the EGR control is performed by performing auxiliary valve opening by this, but the auxiliary cam crest is provided in the exhaust cam 28 as shown in FIG. And the exhaust valve 21 may be opened in the region c. Further, both the intake cam 27 and the exhaust cam 28 may be provided with auxiliary cam peaks.
[0078]
In the above embodiment, the rotary phase difference variable actuator 24 is a vane type, but may be any type such as a helical spline type hydraulic piston (ring gear). Moreover, as a system for receiving the driving force from the crankshaft 15, a sprocket type is used, but a system using a timing pulley may be used.
[0079]
In the above embodiment, the lift amount variable actuator 22a and the rotation phase difference variable actuator 24 are used for EGR control. For example, both actuators 22a and 24 are provided for EGR control in the exhaust system and both in the intake system. The actuators 22a and 24 may be used for controlling a so-called main valve characteristic that determines an output characteristic or the like.
[0080]
In the above embodiment, the valve opening timing of the auxiliary cam crest 27b is changed using the rotation phase difference variable actuator 24. However, this method is not necessarily used, for example, the cam during one rotation of the cam A variable valve operating angle control system or the like that makes the rotational speed of the valve variable may be used.
[0081]
(Second Embodiment)
Next, a second embodiment according to the present invention will be described with reference to FIGS. 10 to 12 mainly focusing on differences from the first embodiment.
[0082]
In the present embodiment, only the lift amount variable actuator 22a is provided in the intake system, and the rotational phase difference variable actuator 24 is not provided. Instead, considering the exhaust pressure pulsation, the shape of the auxiliary cam crest 27b ′ provided on the intake cam 27 is made as shown in FIG.
[0083]
As shown in FIG. 10, the auxiliary cam crest 27b ′ of the intake cam 27 is formed such that the apexes having different heights continuously in the cam shaft direction are biased in a direction gradually increasing backward in the rotation direction of the cam. Has been. This is intended to continuously shift the center of the valve opening period (lift center) to the retard side as the lift amount increases. Further, the position at which the height of the apex of the auxiliary cam crest 27b ′ is maximum is set at the time when the exhaust pressure is highest, that is, at the most retarded angle side of the region a shown in FIG. By forming the auxiliary cam crest 27b ′ of the intake cam 27 with such a shape, as shown in FIG. 11, the lift amount of the auxiliary cam crest 27b ′ is increased while keeping the valve opening start timing substantially constant. At the same time, the center of the lift can be shifted to a higher exhaust pressure. Further, in this case, so-called auxiliary valve characteristics can be changed (EGR control) by the auxiliary cam 27b 'without affecting the so-called main valve characteristics (EX main, IN main) that determine the output characteristics and the like. Also become.
[0084]
The relationship between the lift center of the auxiliary cam crest 27b ′, the lift amount, and the EGR rate that can be secured is shown as a thick line characteristic in FIG. In the present embodiment, as shown in FIG. 12, when the lift amount of the intake valve 20 by the auxiliary cam crest 27b ′ is small, the lift center is set to the low EGR amount request region side. Therefore, the EGR amount can be controlled with high accuracy in the operation region where the EGR rate required by the engine 11 is small. Further, as the lift amount of the intake valve 20 by the auxiliary cam crest 27b ′ increases, the lift center shifts to the high EGR amount request region side. Therefore, in the operation region where the EGR rate required by the engine 11 is large, the supply amount can be reliably ensured. This makes it possible to perform EGR control with a high dynamic range.
[0085]
As described above, according to the present embodiment, the following effects can be obtained.
(1) Since the opening timing of the intake valve 20 by the auxiliary cam 27b ′ is set in consideration of the exhaust pressure pulsation, it is possible to perform optimum control according to the required amount of EGR amount.
[0086]
(2) Highly accurate EGR control is performed in the operation region where the EGR rate required by the engine 11 is small, and control is performed to ensure the required amount sufficiently in the operation region where the EGR rate required by the engine 11 is large. be able to.
[0087]
(3) Since the rotational phase difference variable actuator 24 is not used, the EGR amount can be controlled without changing the so-called main valve characteristic that determines the output characteristic of the engine 11 or the like.
[0088]
Note that the valve characteristic control device of the second embodiment may be modified as follows.
In the above embodiment, the lift center is set so that the lift amount is maximized at a crank angle of about 230 ° in the crank angle. However, the change mode of the lift center is not necessarily limited thereto. For example, it may be set so that the lift amount becomes maximum when the lift center is about 250 ° in crank angle. As shown in FIG. 12, when the lift center is retarded from 240 ° in the crank angle, the EGR rate that is taken in for the lift change does not increase as the lift becomes higher. The accuracy in the operation region where the EGR rate required by the engine 11 is large can be increased. Moreover, the change aspect of these lift centers can be arbitrarily determined according to the exhaust pressure pulsation based on the characteristics of each engine.
[0089]
In the above embodiment, the auxiliary valve opening timing of the intake cam 27 is set in the region a in FIG. 11, but this valve opening timing may be set as the region b. However, in order to obtain the same effect as that of the above embodiment in the region b, it is necessary to use the auxiliary cam crest 27b ″ shown in FIG. 13 instead of the auxiliary cam crest 27b ′. In the cam crest 27b ″, the apexes having different heights continuously in the cam shaft direction are formed so as to be biased in a direction gradually increasing forward in the rotation direction of the cam. Further, the position where the height of the apex of the auxiliary cam crest 27b ″ is maximum is set at the time when the exhaust pressure is highest in the region b shown in FIG. 11, that is, the most advanced angle side of the region b. However, when the exhaust pressure is high, the intake valve 20 is opened with a large lift amount, so that the required EGR amount can be sufficiently secured. Since the lift amount (valve opening amount) of the intake valve 20 is also gradually reduced, EGR control with high accuracy becomes possible.
[0090]
The valve opening of the intake valve 20 by the auxiliary cam crest 27b ″ shown in FIG. 13 may be performed within the region a in FIG. 11. In this case, the lift center, the lift amount, and the EGR rate to be taken in 14 is shown as a thick line characteristic in Fig. 14. As is apparent from Fig. 14, by setting the auxiliary valve opening characteristic of the intake valve 20 in this way, EGR in a region where the lift amount is large. It becomes possible to increase the control accuracy, and it is also possible to secure an EGR amount as soon as the lift amount variable actuator 22a operates.
[0091]
(Third embodiment)
Next, a third embodiment of the valve characteristic control device for an internal combustion engine according to the present invention will be described with reference to FIGS.
[0092]
The target engine in the present embodiment is a known in-cylinder direct injection engine that directly injects fuel into each cylinder. That is, the same reference numerals are given to the members corresponding to the target engine in the previous embodiment for convenience, and the target engine in the present embodiment includes the cylinder block 13 and the piston 12 as shown in FIG. An injector 130 is provided to inject fuel directly into the combustion chamber 17 defined by the above. Further, the valve characteristic control device according to the present embodiment is provided for the exhaust-side camshaft 23, and the configuration thereof is the auxiliary cam crest provided in the exhaust cam 28, as in the first embodiment. A variable lift amount actuator (variable valve lift mechanism) that makes the auxiliary valve opening amount (lift amount) of the exhaust valve 21 variable through the three-dimensional cam shape of the auxiliary cam crest, the exhaust cam shaft 23 and the crankshaft 15 It comprises a rotation phase difference variable actuator (valve timing mechanism) that makes the relative rotation phase variable. In this case, the auxiliary cam crest is provided behind the main cam crest of the exhaust cam 28 in the rotation direction, and opens the exhaust valve 21 as an auxiliary during the intake stroke.
[0093]
By the way, in the cylinder direct injection type engine as described above, by making the fuel injection timing variable, the degree of freedom of formation of the air-fuel mixture can be increased, and fine control for improving fuel efficiency is possible. On the other hand, there is a concern that the fuel is not sufficiently vaporized in the combustion chamber 17 and the combustibility is likely to be hindered. Therefore, in the present embodiment, the auxiliary valve opening timing of the exhaust valve 21 during the fuel injection in the intake stroke is set slightly before the timing at which the fuel injection is performed, that is, slightly before the fuel injection timing. The lead angle is set. As a result, as shown in FIG. 15, the fuel injected from the injector 130 hits the high-temperature EGR gas taken into the combustion chamber 17 during the intake stroke, and the vaporization of the fuel is promoted.
[0094]
Hereinafter, the process of controlling the opening timing of the exhaust valve 21 in the present embodiment will be described with reference to FIGS. 16 and 17 together.
Here, FIG. 16 is a flowchart showing a control procedure related to the above control. This control routine is repeatedly executed by the ECU 120, for example, as an interruption process of a predetermined crank angle cycle. FIG. 17 is a timing chart showing an example of the auxiliary valve opening timing of the exhaust valve 21 corresponding to the fuel injection timing during the intake stroke.
[0095]
In the control of an in-cylinder direct injection type engine, the injection timing is variable in order to inject fuel at an optimal fuel injection timing corresponding to the operating state. This fuel injection timing is roughly classified into whether it is set during the compression stroke for the purpose of stratified combustion or during the intake stroke for the purpose of homogeneous combustion. In addition, the injection timing during each of these strokes is further variable according to the operating state. In the present embodiment, the auxiliary valve opening timing of the exhaust valve 21 is controlled particularly with respect to the fuel injection timing thus variable during the intake stroke.
[0096]
When the control is executed, first, at step 100, it is determined whether or not the injection timing of the engine 11 is being performed during the intake stroke. As a result, if it is determined that the intake stroke injection is being performed, the routine proceeds to step 101. In step 101, as shown in FIG. 17, the opening timing of the auxiliary valve opening (EX2 stage) of the exhaust valve 21 by the auxiliary cam crest 27b is set to the advance side by a predetermined value from the fuel injection timing. The process proceeds to step 102. On the other hand, if it is determined that the intake stroke injection is not being executed, the routine proceeds to step 103, where the opening timing of the auxiliary valve opening of the exhaust valve 21 by the auxiliary cam crest 27b is set to the normal opening that is set in advance. The time (basic value) is set, and the process proceeds to step 102.
[0097]
In step 102, it is determined whether or not an EGR execution condition is satisfied. As a result, if it is determined that it is not established, the routine proceeds to step 104, where the auxiliary lift amount, which is the opening amount of the auxiliary exhaust valve 21 by the auxiliary cam crest 27b, is set to "0". On the other hand, when it is determined in step 102 that the EGR execution condition is satisfied, the routine proceeds to step 105. In step 105, the above-described auxiliary lift amount is calculated in order to secure the required EGR amount. In this embodiment, first, the EGR amount required based on the load based on the detection result of the intake pressure sensor 121 and the rotation speed based on the detection result of the crank sensor 122 is calculated. Next, from the auxiliary lift valve opening start timing set in step 101 or step 103, an auxiliary lift amount corresponding to the required EGR amount is calculated based on the exhaust pressure at the valve opening timing.
[0098]
When the processing of step 104 or step 105 is completed, this routine is once ended, and valve opening timing control and lift amount control for auxiliary lift based on the above set or calculated values are performed through a separate actuator driving routine (not shown). Executed.
[0099]
In the present embodiment, the rotational phase difference variable actuator is controlled according to the fuel injection timing when the intake stroke injection is being executed as described above, and as shown in FIG. The opening timing of auxiliary opening of the exhaust valve 21 is set. As a result, the fuel that is injected each time hits the high-temperature EGR gas introduced by opening the exhaust valve 21, and the vaporization of the fuel is promoted. In addition, the EGR amount is obtained as an accurate required amount based on the exhaust pressure at the set valve opening timing, and the control mode of the lift amount variable actuator is determined based on the obtained EGR required amount. Is determined.
[0100]
As described above, according to the present embodiment, the following effects can be obtained.
(1) By setting the auxiliary valve opening timing of the exhaust valve 21 during the fuel injection in the intake stroke to be slightly advanced from the fuel injection timing, the combustion chamber 17 is in the intake stroke. The fuel injected from the injector 130 hits the high-temperature EGR gas taken in, and the vaporization of the fuel is promoted. Therefore, good combustion can be obtained.
[0101]
(2) The EGR amount to be introduced can be suitably adjusted by making the lift amount variable in conjunction with the auxiliary valve opening timing of the exhaust valve 21.
(3) The required amount of EGR gas can be accurately introduced by calculating the lift amount based on the exhaust pressure at the auxiliary valve opening timing set according to the fuel injection timing.
[0102]
Note that the valve characteristic control device of the third embodiment may be modified as follows.
In the above embodiment, the opening timing of the auxiliary valve opening of the exhaust valve 21 is set to the advance side by a predetermined value from the fuel injection timing. The transition value to the advance side is based on the exhaust pressure. It is also possible to make a fine adjustment. Thereby, the optimum valve opening timing can be set by introducing the required EGR amount while promoting the vaporization of the combustion injected into the combustion chamber 17.
[0103]
In the above embodiment, the lift amount is controlled in consideration of the change in the exhaust pressure due to the start timing of the auxiliary opening of the exhaust valve 21, but the correction of the lift amount due to the exhaust pressure pulsation is not necessarily performed. Even if it does not perform, vaporization of the fuel injected into the combustion chamber 17 can be promoted.
[0104]
In the above embodiment, the lift amount is also variable in conjunction with the auxiliary valve opening timing of the exhaust valve 21, but the lift amount is also fixed to promote the vaporization of the fuel injected into the combustion chamber 17. I can.
[0105]
In addition, there are the following elements that can be commonly changed in the valve characteristic control devices of the above embodiments.
In each of the above embodiments, the intake valve 20 and the exhaust valve 21 are engine driven. However, even when an electromagnetic on-off valve, a rotary valve, or the like is adopted as the intake / exhaust valve, the shape conforming to each of the embodiments The present invention can be applied. In short, apart from the opening and closing of the main intake and exhaust valves that determine the engine output characteristics, the intake and exhaust valves are simultaneously opened based on the auxiliary opening of at least one of the intake and exhaust valves. In the valve characteristic control for controlling the exhaust gas recirculation amount inside the combustion chamber 17 by generating a period of time, the opening timing of the auxiliary valve opening by at least one of the intake valve and the exhaust valve is determined as the operating state of the engine, more specifically, the exhaust gas. What is necessary is just to make it variable according to a pressure.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an engine to which a valve characteristic control device of a first embodiment is applied.
FIG. 2 is a perspective view showing a structure of an intake cam constituting the valve characteristic control device of the embodiment.
FIG. 3 is a partial cross-sectional view showing a configuration of a variable lift amount actuator that constitutes the valve characteristic control device of the embodiment;
FIG. 4 is a partial cross-sectional view showing the configuration of a rotational phase difference variable actuator constituting the valve characteristic control device of the same embodiment.
FIG. 5 is a perspective view showing shapes of an inner gear and a sub gear used in the rotational phase difference variable actuator.
FIG. 6 is a front view showing an internal configuration of the rotational phase difference variable actuator.
FIG. 7 is a timing chart showing a valve characteristic control mode in the same embodiment.
FIG. 8 is a graph showing the relationship between the auxiliary valve opening timing of the intake valve and the EGR amount according to the same embodiment;
FIG. 9 is a timing chart showing a valve characteristic control mode in a modification of the first embodiment.
FIG. 10 is a trihedral view showing the shape of an intake cam used in the second embodiment.
FIG. 11 is a timing chart showing a valve characteristic control mode in the second embodiment.
FIG. 12 is a graph showing the relationship between the auxiliary lift amount, valve opening timing, and EGR amount of the intake valve in the second embodiment.
FIG. 13 is a trihedral view showing the shape of an intake cam used in a modification of the second embodiment.
FIG. 14 is a graph showing the relationship between the auxiliary lift amount, valve opening timing, and EGR amount of the intake valve in the same modification.
FIG. 15 is a partial cross-sectional view of an in-cylinder direct injection engine to which the valve characteristic control device of the third embodiment is applied.
FIG. 16 is a flowchart showing a procedure for calculating an auxiliary valve opening start timing of the exhaust valve in the third embodiment.
FIG. 17 is a timing chart showing a valve characteristic control mode in the third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Valve characteristic control apparatus, 11 ... Engine, 12 ... Piston, 13 ... Cylinder block, 13a ... Oil pan, 14 ... Cylinder head, 14a ... Journal bearing, 14b ... Camshaft bearing cap, 15 ... Crankshaft, 15a ... Timing Sprocket, 15b ... timing chain, 16 ... connecting rod, 17 ... combustion chamber, 18 ... intake port, 19 ... exhaust port, 20 ... intake valve, 20a ... valve lifter, 21 ... exhaust valve, 21a ... valve lifter, 22 ... intake side camshaft , 22a ... lift amount variable actuator, 22b ... end outer peripheral surface, 23 ... exhaust side camshaft, 24 ... rotational phase difference variable actuator, 24a ... timing sprocket, 25 ... timing sprocket, 27 ... intake cam, 27a ... main cam crest 27b Auxiliary cam crest, 28 ... exhaust cam, 31 ... cylinder tube, 31a ... first pressure chamber, 31b ... second pressure chamber, 32 ... piston, 33 ... end cover, 33a ... auxiliary shaft, 33b ... rolling bearing, 34 ... first 1 supply / discharge passage, 35 ... second supply / discharge passage, 36 ... first oil control valve, 37 ... supply passage, 38 ... discharge passage, 39 ... casing, 40 ... first supply / discharge port, 41 ... second supply / discharge port 42 ... 1st discharge port, 43 ... 2nd discharge port, 44 ... supply port, 45 ... valve part, 46 ... coil spring, 47 ... electromagnetic solenoid, 48 ... spool, 51 ... cylinder part, 51a, 51b ... outer peripheral groove , 51c ... inner peripheral surface, 52 ... disc portion, 53 ... external teeth, 54 ... inner gear, 54a ... large diameter gear portion, 54b ... small diameter gear portion, 55 ... bolt, 56 ... sub gear, 56a ... external teeth, 56b ... Tooth, 57 ... Spring washer, 58 ... Bolt, 59 ... Housing, 59a ... Inner peripheral surface, 60 ... Cover, 60a ... Hole, 61 ... Vane rotor, 61a ... Outer peripheral surface, 61b ... Spline part, 61c ... Cylindrical space, 62, 63, 64, 65 ... wall part, 62a, 63a, 64a, 65a, 62b, 63b, 64b, 65b ... recessed part, 66, 67, 68, 69 ... vane, 70 ... first pressure chamber, 71 ... second Pressure chamber, 80 ... Advance angle oil passage opening, 81 ... Delay angle oil passage opening, 84 ... Advance angle control oil passage, 85 ... Delay angle control oil passage, 86 ... Advance angle control oil passage, 87 ... Slow Angle control oil path, 88 ... Advance angle control oil path, 89 ... Delay angle control oil path, 90 ... Lubricating oil path, 91 ... Inner circumferential groove, 92 ... Advance angle control oil path, 93 ... Delay angle control oil path, 94 ... second oil control valve, 95 ... supply passage, 96 ... discharge passage, 102 ... Casing 104 ... first supply / discharge port 106 ... second supply / discharge port 107 ... valve part 108 ... first discharge port 110 ... second discharge port 112 ... supply port 114 ... coil spring 116 ... electromagnetic Solenoid, 118 ... spool, 120 ... ECU, 121 ... intake pressure sensor, 122 ... crank sensor, 130 ... injector.

Claims (8)

In addition to the opening and closing of the main intake and exhaust valves that determine the output characteristics of the internal combustion engine, a period in which the intake and exhaust valves are simultaneously opened is generated based on the auxiliary opening of at least one of the intake and exhaust valves. In the internal combustion engine valve characteristic control method for controlling the exhaust gas recirculation amount in the combustion chamber of the engine by
The opening timing of the auxiliary valve opening by at least one of the intake valve and the exhaust valve is set to a timing at which the exhaust pressure is higher when the required exhaust gas recirculation amount is larger than when the exhaust gas recirculation amount is small. A valve characteristic control method for an internal combustion engine characterized by the above. A cam that drives at least one of the intake valve and the exhaust valve performs auxiliary valve opening during a period other than the valve opening period of the main cam peak in addition to the main cam peak that mainly opens the valve. Thus, the auxiliary cam crest is formed as a three-dimensional cam whose height continuously changes in the axial direction of the cam. Valve operating means,
A variable valve lift mechanism for adjusting a valve lift amount by the auxiliary cam crest by displacing a cam shaft provided with the cam in the axial direction;
The opening timing of the opening and closing target valve according before Symbol auxiliary cam lobes, when the exhaust gas recirculation amount that is required is large, than when the exhaust gas recirculation amount is small, the opening timing varying means for setting the high exhaust pressure timing,
An internal combustion engine valve characteristic control device. 3. The valve characteristic control for an internal combustion engine according to claim 2, wherein the valve opening timing varying means comprises a valve timing varying mechanism for varying a relative rotational phase between an output shaft of the engine and a camshaft provided with the valve operating means. apparatus. The valve characteristic control device for an internal combustion engine according to claim 3, wherein the valve timing variable mechanism is operated in advance according to an exhaust pressure of the engine. The valve opening timing varying means is a three-dimensional deviation of the auxiliary cam crest that is continuously biased in a direction in which the apexes of the auxiliary cam crest continuously differing in height in the cam shaft direction intersect the cam shaft. 3. A valve characteristic control device for an internal combustion engine according to claim 2, comprising a cam profile. 6. The valve characteristic control device for an internal combustion engine according to claim 5, wherein apexes of the auxiliary cam crest having different heights continuously in the cam shaft direction are biased in a direction gradually increasing backward in the rotation direction of the cam. 6. The valve characteristic control device for an internal combustion engine according to claim 5, wherein apexes of the auxiliary cam crest having different heights continuously in the cam shaft direction are biased in a direction gradually increasing forward in the rotation direction of the cam. This is applied to an in-cylinder direct injection internal combustion engine in which fuel is directly injected into the combustion chamber, and the cam that drives the exhaust valve is opened by the main cam peak in addition to the main cam peak that mainly opens the valve. The auxiliary cam crest has an auxiliary cam crest that causes a period in which the intake valve and the exhaust valve are opened at the same time by performing auxiliary valve opening during a period other than the period. Valve operating means formed as a three-dimensional cam continuously changing in the axial direction of the cam;
A variable valve lift mechanism for adjusting a valve lift amount by the auxiliary cam crest by displacing a cam shaft provided with the cam in the axial direction;
Valve characteristics of an internal combustion engine comprising valve opening timing varying means for varying the valve opening timing for opening the exhaust valve through the auxiliary cam peak during the intake stroke of the engine in accordance with the fuel injection timing in the intake stroke Control device.

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