JP4366850B2 - Valve control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve control device that variably controls lift characteristics of an intake valve or an exhaust valve of an internal combustion engine, and more particularly to a valve control device that performs control suitable for fuel cut during engine deceleration.
[0002]
[Prior art]
In order to reduce emissions and reduce fuel consumption when the internal combustion engine is decelerated, it is known to stop the fuel supply, that is, perform a fuel cut when the engine decelerates, for example, when the throttle valve is fully closed.
[0003]
As a valve control device that makes the opening / closing timing of the intake valve or the exhaust valve have an appropriate characteristic at the time of fuel cut during deceleration as described above, there is a conventional one disclosed in JP-A-10-115234. .
[0004]
This is to change the lift amount of the intake valve by switching the valve timing adjusting mechanism for changing the opening timing of the intake valve by advancing or retarding the intake camshaft and the cam for opening and closing the intake valve. And a valve lift amount adjusting mechanism. When the fuel is cut, the valve opening time, that is, the operating angle of the intake valve is shortened, and the phase of the operating angle of the intake valve is greatly advanced by the valve timing adjusting mechanism. As a result, most of the opening period of the intake valve overlaps with the opening period of the exhaust valve. As a result, the time during which the intake valve is open during the intake stroke is shortened, and the amount of air taken into the combustion chamber is reduced.
[0005]
Therefore, a so-called engine braking action is sufficiently generated during the fuel cut, and a temperature drop of the catalyst disposed in the exhaust system is avoided.
[0006]
[Problems to be solved by the invention]
However, in the conventional configuration in which the closing timing of the intake valve is controlled to be greatly advanced with the opening timing at the time of fuel cut as described above, the mechanical control is performed at the time of so-called fuel cut recovery in which fuel injection is resumed from the fuel cut. As a result, there is a possibility that the actual compression ratio is lowered and combustion becomes unstable as a result of temporary operation while the closing timing of the intake valve is located in the middle of the intake stroke.
[0007]
In the low rotation and low load areas such as idle conditions, it is desirable to set the intake valve opening timing later than the intake top dead center from the viewpoint of reducing pump loss and combustion stability. Even for such a demand, the conventional one is greatly different from the valve characteristic during fuel cut, and therefore, the control connection tends to deteriorate.
[0008]
An object of the present invention is to increase the pump loss during fuel cut to sufficiently ensure the engine braking action and at the same time to enable good combustion to be resumed when the fuel cut is recovered.
[0009]
[Means for Solving the Problems]
  In order to solve the above problem, the invention according to claim 1
  A throttle valve for changing the intake air amount of the internal combustion engine;
  A valve opening period varying means for changing the magnitude of the operating angle of the intake valve;
  An operating angle phase variable means for changing the phase of the operating angle of the intake valve;
  The throttle valve is fully closedFuel cut means for stopping fuel supply at a predetermined deceleration of the internal combustion engine;
  In an internal combustion engine comprising:
  When fuel is cut by the fuel cut meansAnd during subsequent fuel cut recoveryIn addition,The intake valve opening timing is set to be retarded from the top dead center so as to have a negative overlap,Intake valve closing timingThe actual compression ratio does not decrease as the combustion stability deterioratesIt is characterized by controlling to approximately the bottom dead center.
[0010]
  Thus, if the intake valve closing timing is substantially at the bottom dead center, the actual compression ratio can be secured sufficiently large when the fuel cut is shifted to the fuel cut recover.And since it becomes what is called a minus overlap with respect to an exhaust valve opening period, a negative pressure generate | occur | produces in a cylinder at the beginning of an intake stroke, and gas flow becomes active.
[0011]
  According to a second aspect of the present invention, there is provided a lift amount varying means for changing the lift amount during the opening period of the intake valve.FurtherPrepared,Above fuelAt the time of charge cut, intake valveOfIt is characterized in that the lift amount is set lower than in the steady state.
[0013]
  Claim 1, 2Claims dependent on3The invention according to
  A valve opening period variable means for changing the magnitude of the operating angle of the exhaust valve;
  Working angle phase varying means for changing the working angle phase of the exhaust valve;
  Further comprising
  When the fuel is cut, set the exhaust valve opening time., Near the bottom dead center where the cylinder has negative pressureIt is characterized by controlling to.
[0014]
  In particular, the claims4The invention according to the invention is characterized in that the exhaust valve opening timing is retarded from the steady time at the time of the fuel cut.
[0015]
  Claims3, 4Claims dependent on5The invention according to the invention is characterized in that the exhaust valve closing timing is controlled to a position advanced from the top dead center at the time of the fuel cut.
[0016]
  And claims6In the invention according to the invention, at the time of the fuel cut, the intake valve opening timing is controlled to a position delayed from the top dead center,
  The period from the top dead center to the intake valve opening timing is set larger than the period from the exhaust valve closing timing to the top dead center.
[0017]
  The valve opening period varying means of the intake valve or the exhaust valve is, for example, a claim7As described above, a plurality of types of cams having different cam profiles are provided, and the cam for opening and closing the valve is selectively switched.
[0018]
  Further claims8As described above, the valve opening period variable means or the lift amount variable means of the intake valve includes an eccentric cam that is rotationally driven by a drive shaft, a link arm that is fitted to the outer periphery of the eccentric cam so as to be relatively rotatable, and the drive A rotatable control shaft provided in parallel with the shaft and provided with an eccentric cam portion; a rocker arm rotatably mounted on the eccentric cam portion of the control shaft and swung by the link arm; and the drive A swing cam that is rotatably supported by the shaft and is connected to the rocker arm via a link and presses the intake valve by swinging along with the rocker arm. By changing the rotational position of the cam portion, the operation angle and lift of the intake valve are simultaneously increased or decreased.
[0019]
【The invention's effect】
  According to the first aspect of the present invention, when the fuel is cut, the intake valve closing timing is set to substantially bottom dead center, so that the pump loss can be prevented from being reduced due to the smaller operating angle, and the engine braking action is enhanced. At the same time, the actual compression ratio becomes sufficiently high at the time of fuel cut recovery, and the combustion stability immediately after the fuel cut recovery is improved.
  Furthermore, by retarding the opening timing of the intake valve from the top dead center, a negative overlap with the exhaust valve can be achieved, so that fresh air can be reliably prevented from being blown into the exhaust side, and at the beginning of the intake stroke. Since the gas flow in the cylinder becomes active due to the generation of the negative pressure, even when the operating angle is reduced, it is possible to ensure a more stable ignition performance at the time of fuel cut recovery while suppressing a decrease in pump loss.
[0020]
According to the invention of claim 2, by further reducing the lift amount of the intake valve, the throttle loss due to the intake valve is increased, the pump loss during fuel cut is increased, and the engine brake is more strongly secured. .
[0022]
  Claim3According to the inventionSwellDuring the second half of the tension stroke, negative pressure is generated in the cylinder, and when the exhaust valve is opened, the exhaust valve sucks the exhaust gas back into the cylinder, increasing the pump loss and ensuring the engine brake. .
[0023]
  Especially claims4According to this invention, the exhaust valve opening timing is advanced from the steady time, so that the energy recovered in the expansion stroke is reduced, the pump loss is further increased, and the engine brake is more reliably secured. .
[0024]
  Claim5According to this invention, since the exhaust valve closing timing is at a position advanced from the top dead center, the prevention of inflow of fresh air into the exhaust system is more sure. Accordingly, it is possible to suppress a decrease in the catalyst temperature during the fuel cut due to fresh air while ensuring an effective pump loss during the fuel cut.
[0025]
  Claim6According to the present invention, in the minus overlap, the period on the intake valve side with respect to the top dead center is longer than the period on the exhaust valve side. A negative pressure develops at the valve timing, and the pump loss at the time of fuel cut, that is, the engine braking action increases.
[0026]
  Claim7According to the invention, it is possible to easily obtain the desired characteristics at the time of fuel cut by the valve opening period variable means by switching the cam.
[0027]
  And claims8According to the invention, when the operating angle is reduced, the lift amount is simultaneously lowered, and it is possible to easily achieve an increase in pump loss by reducing the lift while optimizing the opening / closing timing. .
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an automobile gasoline engine will be described.
[0029]
FIG. 1 is an explanatory diagram showing the configuration of a variable valve mechanism for an intake valve used in a valve control apparatus according to the present invention. This variable valve mechanism is a lift / control valve that changes the lift / operating angle of the intake valve. The operating angle variable mechanism 1 is combined with a phase variable mechanism 2 that advances or retards the phase of the operating angle (phase with respect to a crankshaft (not shown)).
[0030]
FIG. 2 shows only the lift / operating angle variable mechanism 1, and the lift / operating angle variable mechanism 1 will be described with reference to FIGS. 1 and 2. The lift / operating angle variable mechanism 1 has been previously proposed by the applicant of the present application. However, since it has been publicly known, for example, in Japanese Patent Application Laid-Open No. 11-107725, only the outline thereof will be described.
[0031]
The lift / operating angle variable mechanism 1 is a hollow shape rotatably supported by an intake valve 12 slidably provided on a cylinder head 11 via a valve guide (not shown) and a cam bracket 14 above the cylinder head 11. Drive shaft 13, an eccentric cam 15 fixed to the drive shaft 13 by press-fitting or the like, and a cam bracket 14 that is rotatably supported above the drive shaft 13 and arranged in parallel with the drive shaft 13. A control shaft 16, a rocker arm 18 that is swingably supported by the eccentric cam portion 17 of the control shaft 16, a swing cam 20 that abuts against a tappet 19 disposed at the upper end of each intake valve 12, It has. The eccentric cam 15 and the rocker arm 18 are linked by a link arm 25, and the rocker arm 18 and the swing cam 20 are linked by a link member 26.
[0032]
As will be described later, the drive shaft 13 is driven by a crankshaft of an engine via a timing chain or a timing belt.
[0033]
The eccentric cam 15 has a circular outer peripheral surface, the center of the outer peripheral surface is offset from the shaft center of the drive shaft 13 by a predetermined amount, and the annular portion 25a of the link arm 25 is rotatable on the outer peripheral surface. Is fitted.
[0034]
The rocker arm 18 has a substantially central portion supported by the eccentric cam portion 17, and an extension portion 25 b of the link arm 25 is linked to one end portion of the rocker arm 18, and the link member 26 is connected to the other end portion. The upper end is linked. The eccentric cam portion 17 is eccentric from the axis of the control shaft 16, and accordingly, the rocking center of the rocker arm 18 changes according to the angular position of the control shaft 16.
[0035]
The rocking cam 20 is fitted to the outer periphery of the drive shaft 13 and is rotatably supported. A lower end portion of the link member 26 is linked to an end portion 20a extending to the side. On the lower surface of the swing cam 20, a base circle surface 24a that forms a concentric arc with the drive shaft 13, a cam surface 24b extending in a predetermined curve from the base circle surface 24a to the end portion 20a, The base circle surface 24a and the cam surface 24b are in contact with the upper surface of the tappet 19 according to the swing position of the swing cam 20.
[0036]
That is, the base circle surface 24a is a section where the lift amount becomes 0 as a base circle section, and when the swing cam 20 swings and the cam surface 24b contacts the tappet 19, it gradually lifts. Become. A slight ramp section is provided between the base circle section and the lift section.
[0037]
As shown in FIG. 1, the control shaft 16 is configured to rotate within a predetermined rotation angle range by a lift / operation angle control hydraulic actuator 31 provided at one end. The hydraulic pressure supply to the lift / operating angle control hydraulic actuator 31 is controlled by the first hydraulic control valve 32 based on a control signal from the engine control unit 33. Reference numeral 30 denotes a hydraulic pump serving as a hydraulic source.
[0038]
The operation of the variable lift / operating angle mechanism 1 will be described. When the drive shaft 13 rotates, the link arm 25 moves up and down by the cam action of the eccentric cam 15, and the rocker arm 18 swings accordingly. The swing of the rocker arm 18 is transmitted to the swing cam 20 via the link member 26, and the swing cam 20 swings. The tappet 19 is pressed by the cam action of the swing cam 20, and the intake valve 12 is lifted.
[0039]
Here, when the angle of the control shaft 16 changes via the lift / operating angle control hydraulic actuator 31, the initial position of the rocker arm 18 changes, and consequently, the initial swing position of the swing cam 20 changes.
[0040]
For example, if the eccentric cam portion 17 is positioned upward in the figure, the rocker arm 18 is positioned upward as a whole, and the end 20a of the swing cam 20 is relatively lifted upward. That is, the initial position of the swing cam 20 is inclined in the direction in which the cam surface 24 b is separated from the tappet 19. Therefore, when the swing cam 20 swings with the rotation of the drive shaft 13, the base circle surface 24a continues to contact the tappet 19 for a long time, and the period during which the cam surface 24b contacts the tappet 19 is short. Therefore, the lift amount is reduced as a whole, and the angle range from the opening timing to the closing timing, that is, the operating angle is also reduced.
[0041]
Conversely, if the eccentric cam portion 17 is positioned downward in the figure, the rocker arm 18 is positioned downward as a whole, and the end portion 20a of the swing cam 20 is pushed downward relatively. That is, the initial position of the swing cam 20 is inclined in the direction in which the cam surface 24 b approaches the tappet 19. Accordingly, when the swing cam 20 swings with the rotation of the drive shaft 13, the portion that contacts the tappet 19 immediately shifts from the base circle surface 24a to the cam surface 24b. Therefore, the lift amount is increased as a whole, and the operating angle is increased.
[0042]
Since the position of the eccentric cam portion 17 can be continuously changed, the valve lift characteristic changes continuously as shown in FIG. That is, the lift and the operating angle can be continuously expanded and contracted simultaneously. In particular, in this case, the opening timing and closing timing of the intake valve 12 change substantially symmetrically as the lift and operating angle change.
[0043]
Next, as shown in FIG. 1, the phase variable mechanism 2 is configured so that the sprocket 35 provided at the front end of the drive shaft 13 and the sprocket 35 and the drive shaft 13 are relatively moved within a predetermined angle range. And a hydraulic actuator 36 for phase control that is rotated to the right. The sprocket 35 is linked to the crankshaft via a timing chain or timing belt (not shown). The hydraulic pressure supply to the phase control hydraulic actuator 36 is controlled by a second hydraulic control valve 37 based on a control signal from the engine control unit 33. Reference numeral 30 denotes a hydraulic pump. Due to the hydraulic pressure control to the phase control hydraulic actuator 36, the sprocket 35 and the drive shaft 13 are relatively rotated, and the phase of the operating angle is delayed as shown in FIG. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The phase variable mechanism 2 is not limited to a hydraulic one, and various configurations such as one using an electromagnetic actuator are possible.
[0044]
The lift / working angle variable mechanism 1 and the phase variable mechanism 2 may be controlled by providing a sensor for detecting an actual lift / working angle or phase and performing a closed loop control or depending on operating conditions. It is also possible to simply perform open loop control.
[0045]
Next, the operation during engine deceleration will be described based on the flowchart shown in FIG.
[0046]
First, in step 101, it is determined whether or not the engine operating condition is a predetermined fuel cut condition. For example, when the throttle valve is fully closed in a region equal to or higher than the number of revolutions after completion of warm-up, fuel cut is executed. If it is a fuel cut condition, the routine proceeds to step 102, where the required intake valve operating angle is read. In step 103, the above-described lift / operation angle variable mechanism 1 is controlled in accordance with the read target value of the operation angle. In the subsequent step 104, a necessary phase angle is calculated from the required operating angle at that time and the target intake valve closing timing (IVC). In particular, the phase angle is determined so that the intake valve closing timing is substantially at the bottom dead center (BDC). In step 105, the above-described phase variable mechanism 2 is controlled according to the calculated phase angle.
[0047]
FIG. 6 is a time chart for explaining the operation of each part at the time of deceleration. As shown in the figure, when the throttle valve (accelerator) is fully closed, fuel cut is started, and thereafter, when the vehicle speed decreases to a constant vehicle speed. The fuel injection is resumed. The operating angle and phase of the intake valve change greatly with the start of the fuel cut, but during the fuel cut recovery, the characteristics during the fuel cut remain almost unchanged and remain unchanged.
[0048]
FIG. 7 shows a valve timing diagram of the intake valve (INT) and the exhaust valve (EXH). In particular, for the intake valve, the characteristics of both steady running and fuel cut are illustrated. The characteristic described as “normal” is a fixed characteristic example in the case of a general non-variable valve mechanism. In this embodiment, the exhaust valve has a fixed characteristic.
[0049]
Further, FIG. 8 shows a conceptual PV diagram based on valve characteristics during fuel cut.
[0050]
As shown in these figures, the operating angle of the intake valve during fuel cut is set to a small operating angle so as to be equivalent to the fuel cut recovery or the idle condition. As described above, the intake valve closing timing (IVC) is set to a position substantially at the bottom dead center, more specifically, slightly behind the bottom dead center. Accordingly, the intake valve opening timing (IVO) is at a position considerably delayed from the top dead center, resulting in a minus overlap.
[0051]
The PV diagram at the time of fuel cut set in this way is as shown in FIG. 8, and the gas in the cylinder adiabatically expands from the top dead center until the intake valve opens, and the conventional top dead center is obtained. The pump loss will be reduced compared to the case where it is open at the point. However, after that, since the valve opening area is narrower than before for each crank angle, the pump loss increases conversely. Therefore, even if the negative overlap is achieved as described above and the operating angle is further reduced, the reduction in pump loss is small. That is, sufficient engine braking action can be obtained.
[0052]
On the other hand, the PV diagram during fuel cut recovery is as shown in FIG. In the operation region during the fuel cut recovery, the load and the rotational speed are generally low, and the required amount of air is small. Therefore, if the intake valve closing timing (IVC) is advanced as in the comparative example, the pump loss is reduced. However, when such a setting is made, the actual compression ratio is lowered, the pressure and temperature at the time of ignition are lowered, and the combustion stability is deteriorated. Therefore, when using a small operating angle in this region, it is desirable to set the intake valve closing timing closer to the bottom dead center from the viewpoint of securing the actual compression ratio. In this embodiment, since the intake valve closing timing is set to approximately bottom dead center during fuel cut, combustion stability during fuel cut recovery can be ensured without being affected by control response delay.
[0053]
Next, a second embodiment of the present invention will be described.
[0054]
In the second embodiment, the variable valve mechanism described above is also provided on the exhaust valve side, and the opening / closing timing and lift of both the intake valve and the exhaust valve can be variably controlled. The configuration of the variable valve mechanism on the exhaust side is basically the same as the configuration on the intake side described above, and a description thereof will be omitted.
[0055]
FIG. 10 is a flowchart showing control of the exhaust side variable valve mechanism at the time of engine deceleration. The control on the intake side is the same as in FIG.
[0056]
First, in step 111, it is determined whether or not the engine operating condition is a predetermined fuel cut condition. If it is a fuel cut condition, the process proceeds to step 112, and the required exhaust valve operating angle is read. In step 113, the exhaust-side lift / operating angle variable mechanism 1 is controlled in accordance with the read target value of the operating angle. In the following step 114, a necessary phase angle is calculated from the required operating angle at that time and the target exhaust valve opening timing (EVO). In particular, the phase angle is determined so that the exhaust valve opening timing is near bottom dead center, for example, about 20 ° CA before bottom dead center. In step 115, the exhaust-side phase variable mechanism 2 is controlled according to the calculated phase angle.
[0057]
FIG. 11 is a time chart for explaining the operation of each part at the time of deceleration. As shown in the figure, when the throttle valve (accelerator) is fully closed, fuel cut is started, and thereafter, when the vehicle speed decreases to a constant vehicle speed. The fuel injection is resumed. The operating angle and phase of the intake valve change greatly with the start of the fuel cut, but during the fuel cut recovery, the characteristics during the fuel cut remain almost unchanged and remain unchanged. The operating angle of the exhaust valve has the same tendency. On the other hand, the phase of the exhaust valve almost returns to the state before the fuel cut when the fuel cut is recovered.
[0058]
FIG. 12 shows a valve timing diagram of the intake valve (INT) and the exhaust valve (EXH). In particular, the characteristics at both idling (recovery) and fuel cut are illustrated. The characteristic described as “conventional” is a fixed characteristic example in the case of a general non-variable valve mechanism.
[0059]
Furthermore, FIG. 13 shows a conceptual PV diagram based on the valve characteristics during fuel cut.
[0060]
In this embodiment, the exhaust valve operating angle at the time of fuel cut is set to a small operating angle similar to the idle condition. The exhaust valve opening timing is near the bottom dead center. Therefore, when the fuel cut is executed, the negative pressure in the cylinder develops in the second half of the expansion stroke. Since the exhaust valve is opened here, the working gas flows from the exhaust side, and the pump loss increases as shown in FIG.
[0061]
Further, since the exhaust side is set to a small operating angle, a negative overlap is set during fuel cut, so that fresh air can be reliably prevented from flowing into the exhaust side, and a decrease in catalyst temperature can be suppressed. Further, as shown in FIG. 13, by giving the negative overlap amount b on the intake side larger than the negative overlap amount a on the exhaust side, the negative pressure in the cylinder is further developed, and the flow velocity at the valve opening is increased. Further, the pump loss can be further increased.
[0062]
As shown in FIG. 11, immediately before the engine speed to reach the fuel cut recovery, the phase of the exhaust valve operating angle is changed to suppress the internal EGR, thereby ensuring combustion during recovery. be able to. FIG. 14 shows a flowchart of phase control up to fuel cut recovery. As shown in the figure, when it is determined in step 121 that the fuel cut condition is satisfied, the routine proceeds to step 122, where it is determined whether the actual rotational speed has decreased below the rotational speed rpm1 slightly higher than the fuel cut recovery rotational speed. . When the rotation speed is lower than rpm1, the process proceeds to step 123. In step 123, in order to ensure combustion stability at the time of fuel cut recovery, the exhaust valve closing timing (EVC) is set to approximately top dead center, and a necessary phase angle is calculated. In addition, since internal recirculation that allows combustion is allowed, the phase angle may be calculated so that a predetermined overlap amount is obtained. In step 124, the exhaust-side phase variable mechanism 2 is controlled to the phase angle based on step 123.
[0063]
Next, FIGS. 15 to 19 show a third embodiment.
[0064]
In this embodiment, as shown in FIGS. 17 and 18, when the fuel is cut, the operating angle of the exhaust valve is set to a large operating angle, and the exhaust valve opening timing is advanced to the middle of the expansion stroke. The As a result, as shown in the PV diagram of FIG. 19, the energy recovered in the expansion stroke is reduced and the pump loss is increased, so that the engine braking action is increased.
[0065]
Here, in this embodiment, the phase control is performed with priority on the exhaust valve side in particular, and then the operating angle is expanded. This is to prevent interference between the exhaust valve and the piston.
[0066]
That is, as shown in the flowchart of FIG. 15, in step 131, it is determined whether or not the engine operating condition is a predetermined fuel cut condition, and if it is the fuel cut condition, the process proceeds to step 132 and the phase angle of the exhaust valve is determined. Is read as the most advanced position. In step 133, the exhaust-side phase variable mechanism 2 is controlled along the target value of the phase angle. Next, in step 134, the required exhaust valve operating angle is calculated from the phase angle of the operating angle at that time and the necessary minus overlap setting (the relationship of a <b described above). In step 135, the exhaust-side variable lift / operating angle mechanism 1 is controlled in accordance with the calculated target value of the operating angle.
[0067]
In addition, when calculating the optimal exhaust valve closing timing (EVC) and controlling based on this EVC, the phase and the operating angle can be changed simultaneously.
[0068]
Further, at the time of fuel cut recovery, as shown in the flowchart of FIG. 16, the operating angle and phase angle are controlled so as to be optimal at the time of fuel cut recovery at the rotational speed rpm1 immediately before the fuel cut recovery, and combustion at the time of recovery is ensured. It is supposed to be.
[0069]
In each of the above embodiments, the lift / operating angle variable mechanism 1 as shown in FIGS. 1 and 2 is used to change the lift and the operating angle. However, the present invention is not limited to this. Absent.
[0070]
For example, in U.S. Pat. No. 4,151,817 and JP-A-6-299827, two types of cams having different profiles are arranged side by side on a camshaft, and a main rocker arm and a sub rocker arm that follow each are provided as necessary. A variable valve mechanism is known in which a cam that substantially opens and closes a valve is selectively switched by switching to a connected state or a disengaged state. Further, JP-A-5-10161 discloses three types of variable valve mechanisms. Although a variable valve mechanism that switches cams is disclosed, the present invention can be similarly applied even if the lift / operating angle is changed stepwise by this type of variable valve mechanism.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a variable valve mechanism used in a valve control device according to the present invention.
FIG. 2 is a cross-sectional view showing a lift / operating angle variable mechanism.
FIG. 3 is a characteristic diagram showing changes in lift / operating angle characteristics by a variable lift / operating angle mechanism;
FIG. 4 is a characteristic diagram showing a phase change of a valve lift characteristic by a phase variable mechanism.
FIG. 5 is a flowchart showing control of an intake valve during engine deceleration.
FIG. 6 is a time chart showing the operation during deceleration.
FIG. 7 is a valve timing diagram of an intake valve and an exhaust valve.
FIG. 8 is a PV diagram according to valve characteristics during fuel cut.
FIG. 9 is a PV diagram during fuel cut recovery.
FIG. 10 is a flowchart showing control of an exhaust-side variable valve mechanism in the second embodiment.
FIG. 11 is a time chart showing an operation at the time of deceleration in the second embodiment.
FIG. 12 is a valve timing diagram of an intake valve and an exhaust valve in the second embodiment.
FIG. 13 is a PV diagram during fuel cut in the second embodiment.
FIG. 14 is a flowchart showing phase angle control during fuel cut recovery.
FIG. 15 is a flowchart showing control of an exhaust side variable valve mechanism in a third embodiment.
FIG. 16 is a flowchart showing control during fuel cut recovery in the third embodiment.
FIG. 17 is a time chart showing an operation at the time of deceleration in the third embodiment.
FIG. 18 is a valve timing diagram of an intake valve and an exhaust valve in the third embodiment.
FIG. 19 is a PV diagram during fuel cut in the third embodiment.
[Explanation of symbols]
1 ... Lift / operating angle variable mechanism
2 ... Phase variable mechanism
33 ... Engine control unit

Claims (8)

A throttle valve for changing the intake air amount of the internal combustion engine;
A valve opening period variable means for changing the size of the operating angle of the intake valve;
An operating angle phase variable means for changing the phase of the operating angle of the intake valve;
Fuel cut means for stopping fuel supply at a predetermined deceleration of the internal combustion engine in which the throttle valve is fully closed ;
In an internal combustion engine comprising:
At the time of fuel cut by the fuel cut means and at the time of subsequent fuel cut recovery , the intake valve opening timing is retarded from the top dead center so as to be a negative overlap, and the intake valve closing timing is burned A valve control apparatus for an internal combustion engine, wherein the control is performed at a substantially bottom dead center that does not cause a decrease in the actual compression ratio as the stability deteriorates . Further comprising lift amount variable means for changing the lift amount during the valve opening period of the intake valve;
When the fuel cut, the engine valve controller according to claim 1, characterized in that the set lower than the steady state of the lift amount of the intake valves. A valve opening period variable means for changing the magnitude of the operating angle of the exhaust valve;
An operating angle phase variable means for changing the phase of the operating angle of the exhaust valve;
Further comprising
3. The valve control device for an internal combustion engine according to claim 1, wherein the valve opening timing of the exhaust valve is controlled in the vicinity of bottom dead center where the inside of the cylinder becomes negative pressure when the fuel is cut. 4. The valve control apparatus for an internal combustion engine according to claim 3 , wherein the exhaust valve opening timing is retarded from the steady time when the fuel is cut. During the fuel cut, the engine valve controller according to claim 3 or 4, characterized in that for controlling the exhaust valve closing timing at a position advanced from the top dead center. At the time of the fuel cut, the intake valve opening timing is controlled to a position delayed from the top dead center,
6. The valve control device for an internal combustion engine according to claim 5 , wherein a period from the top dead center to the intake valve opening timing is set larger than a period from the exhaust valve closing timing to the top dead center. . The valve opening period varying means for the intake valve or the exhaust valve includes a plurality of types of cams having different cam profiles, and is configured to selectively switch a cam for opening and closing the valve. The valve control device for an internal combustion engine according to any one of 1 to 6 . The intake valve opening period variable means or lift amount variable means includes an eccentric cam that is rotationally driven by a drive shaft, a link arm that is fitted to the outer periphery of the eccentric cam so as to be relatively rotatable, and a parallel to the drive shaft. A rotatable control shaft provided with an eccentric cam portion, a rocker arm that is rotatably attached to the eccentric cam portion of the control shaft and is oscillated by the link arm, and is rotatable on the drive shaft And a rocking cam that is coupled to the rocker arm via a link and pushes the intake valve by rocking with the rocker arm, and the rotation of the eccentric cam portion of the control shaft. The internal combustion engine according to any one of claims 1 to 6 , wherein the operating angle and lift of the intake valve are increased and decreased simultaneously by changing the moving position. Engine valve control device.

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