JP4928154B2 - Variable valve control device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve control apparatus for an internal combustion engine that controls a lift / operating angle variable mechanism that changes a lift and an operating angle of an engine valve and a center phase variable mechanism that changes a center phase of the operating angle of the engine valve. About.

  Patent Document 1 includes a lift / operating angle variable mechanism that continuously changes the operating angle and lift of the intake valve, and a center phase variable mechanism that continuously changes the central phase of the operating angle of the intake valve. In the internal combustion engine, when the change amount of the lift / working angle and the center phase exceeds a predetermined threshold value, after driving one of the lift / working angle variable mechanism and the center phase variable mechanism first, It is described to drive.

According to the above drive control, it is possible to prevent the valve lift characteristic from becoming incorrect during switching, and it is possible to prevent the hydraulic source from becoming large when both mechanisms are hydraulically driven.
JP 2001-280167 A

By the way, according to the above prior art, when it is necessary to largely operate both mechanisms, one of the mechanisms is driven first, and the control amount of the valve mechanism that has been driven in advance converges to the target value. The other valve mechanism is configured to drive, and during acceleration, driving of the center phase variable mechanism that changes the center phase is given priority.
For this reason, although the center phase can be changed with good response to the acceleration request, since the lift change is postponed, the opening area of the intake valve does not increase, and the increase in intake air amount is delayed. There was a problem that acceleration performance decreased.

  The present invention has been made in view of the above problems, and provides a variable valve control apparatus for an internal combustion engine that can improve the drivability at the time of transition while preventing the valve lift characteristics from becoming incorrect during switching. The purpose is to provide.

Therefore, according to the first aspect of the present invention, in the process in which the center phase of the intake valve operating angle is retarded toward the target value by the center phase variable mechanism , the opening timing of the intake valve is determined by the actual value of the center phase at that time. By limiting the operating angle by the lift and operating angle variable mechanism to the upper limit value or less by setting the operating angle that becomes the target opening timing as an upper limit value, the opening timing of the intake valve is limited from being advanced. When the operating angle is limited based on the upper limit value, the operating angle of the intake valve is held at the previous value when the operating angle is changed in response to a request for increasing the operating angle .
According to the above invention, in the process in which the central phase of the operating angle of the intake valve changes toward the target by the center phase variable mechanism, the operating angle is changed by the lift and the operating angle variable mechanism at the same time, so that the intake valve In order to limit the opening angle of the engine from changing the advance angle, the operating angle by the lift and operating angle variable mechanism is set with the operating angle at which the opening timing of the intake valve becomes the target opening timing with the actual value of the center phase at that time Is limited to the upper limit value or less.

Therefore, the central phase variable mechanism and the lift / operating angle variable mechanism operate simultaneously, so that the opening timing of the intake valve is restricted from being advanced, and the operation of the lift and operating angle variable mechanism is greatly delayed. It is possible to prevent the drivability during transition from deteriorating.
In addition, when the limitation of the operating angle based on the upper limit value causes the operating angle to be changed in response to a request to increase the operating angle, the operating angle is held at the previous value, and the operating angle is set based on the upper limit value. Even if the limit is set, the operating angle is not changed in a decreasing manner, and the operating angle is changed toward the target while limiting the amount of change.
Therefore, it is possible to limit the excessive change of the operating angle and the lift with respect to the change of the center phase while avoiding the operating angle and the lift from decreasing with respect to the increase request due to the limitation of the operating angle.
The invention according to claim 2 determines that the center phase is a process of changing the retardation toward the target value based on a deviation between the target value of the center phase and the actual center phase at that time. It is characterized by.

According to the above invention, as the period from when the target value of the center phase in the center phase varying mechanism changes and a deviation occurs with respect to the actual center phase, Judge the process of changing the angle of delay toward the target value .
Thus, the center phase variable mechanism can accurately determine the state in which while changing retarded toward the target center phase of the operating angle of the intake valve.

Embodiments of the present invention will be described below.
1 to 3 show an embodiment in which a variable valve control apparatus according to the present invention is applied to an intake valve side of an internal combustion engine for a vehicle.
Each cylinder of the internal combustion engine is provided with a pair of intake valves 12 and 12 and an exhaust valve (not shown). The intake and exhaust valves are slidably supported by the cylinder head 11.

Then, the variable valve control device includes a lift / operating angle variable mechanism (lift and operating angle variable mechanism) 1 that continuously changes the lift and operating angle of the intake valves 12, 12 and the operating angle of the intake valves 12, 12. The center phase variable mechanism 2 that continuously changes the center phase of the first and second mechanisms, and a control unit 37 that drives and controls both the mechanisms 1 and 2 according to the engine operating state.
The lift / operating angle variable mechanism 1 includes a hollow drive shaft 13 rotatably supported by a bearing 14 above the cylinder head 11, two drive cams 15 and 15 fixed to the drive shaft 13, and a drive. Sliding cams 17 and 17 which are supported by the shaft 13 so as to be swingable, slide in contact with the flat upper surfaces 16a and 16a of the valve lifters 16 and 16 to open the intake valves 12 and 12, and the drive cam 15 swings. A transmission mechanism 18 that is linked to the cams 17 and 17 and transmits the rotational force of the drive cam 15 as the swinging force of the swing cams 17 and 17, and a control mechanism 19 that variably controls the operating position of the transmission mechanism 18. And.

The drive shaft 13 receives torque from the crankshaft of the engine via a timing chain (not shown) wound around the timing sprocket 40 of the center phase variable mechanism 2 provided at one end.
The bearing 14 includes a main bracket 14a that supports an upper portion of the drive shaft 13, and a sub bracket 14b that is provided at an upper end portion of the main bracket 14a and rotatably supports the control shaft 32. 14b is fastened together by a pair of bolts 14c and 14c.

Both drive cams 15 are substantially ring-shaped, and include a cam main body 15a and a cylindrical portion 15b provided integrally with the cam main body 15a, and an insertion hole 15c of the drive shaft 13 is formed therethrough. The axis X of the cam body 15a is offset from the axis Y of the drive shaft 13 by a predetermined amount in the radial direction.
Each drive cam 15 is fixed to the drive shaft 13 at a position where it does not interfere with both valve lifters 16, 16, and the outer peripheral surfaces 15d, 15d of both cam bodies 15a, 15a are formed in the same cam profile. ing.

The swing cam 17 is mainly composed of a pair of cam bodies having a cam surface 22 formed on the outer periphery, and a support hole in which a drive shaft 13 is fitted and inserted into a base end portion 20 on one end side thereof so as to be rotatably supported. 20a is formed through, and a pin hole 21a is formed through the cam nose 21 at the other end.
The cam surface 22 includes a base circle surface 22a on the base end portion 20 side, a ramp surface 22b extending in an arc from the base circle surface 22a to the cam nose portion 21 side, and a lift on the tip side of the ramp surface 22b. The base circle surface 22a, the ramp surface 22b, and the lift surface 22c come into contact with predetermined positions on the valve lifter upper surfaces 16a according to the swing position of the swing cam 17.

The transmission mechanism 18 includes a rocker arm 23 disposed above the drive shaft 13, a link arm 24 linking the one end 23 a of the rocker arm 23 and the drive cam 15, the other end 23 b of the rocker arm 23, and the swing cam 17. And a link rod 25 that is a linking member that links the two.
A cylindrical base 23 c provided at the center of the rocker arm 23 is rotatably supported by the control cam 33.

In addition, a pin hole 23d through which a pin 26 connected to the link arm 24 is rotatably inserted is formed in one end 23a of each base 23c, while the other end 23b of each base 23c is formed in the other end 23b. A pin hole 23e is formed through which a pin 27 is rotatably connected to one end 25a of each link rod 25.
The link arm 24 includes an annular base 24a and a projecting end 24d projecting at a predetermined position on the outer peripheral surface of the base 24a. At the center of the base 24a, the cam body 15a of the drive cam 15 is provided. A fitting hole 24c is formed in the outer peripheral surface so as to be freely rotatable, and a pin hole 24d through which the pin 26 is rotatably inserted is formed in the protruding end 24b.

Furthermore, pin insertion holes 25c and 25d are formed in both end portions 25a and 25b of the link rod 25, and the pin insertion holes 25c and 25d swing with the pin holes 23e on the rocker arm 23 on the other end portion 23b. The end portions of the pins 27 and 28 respectively inserted into the pin holes 21a of the cam nose portion 21 of the cam 17 are rotatably inserted.
The link rod 25 regulates the maximum swing range of the swing cam 17 within the swing range of the rocker arm 23.

In addition, snap rings 29, 30, and 31 for restricting the movement of the link arm 24 and the link rod 25 in the axial direction are provided at one end portions of the pins 26, 27, and 28, respectively.
The control mechanism 19 includes a control shaft 32, a control cam 33 that is fixed to the outer periphery of the control shaft 32 and serves as a rocking fulcrum of the rocker arm 23, and an actuator 34 that controls the rotational position of the control shaft 32. .

The control shaft 32 is provided in parallel with the drive shaft 13, and is rotatably supported between the bearing groove at the upper end portion of the main bracket 14a of the bearing 14 and the sub bracket 14b as described above.
On the other hand, each control cam 33 has a cylindrical shape, and the position of the shaft center P1 is eccentric from the shaft center P2 of the control shaft 32 by α.

The actuator 34 has a rotational force applied to the control shaft 32 through meshing between a first spur gear 35 provided at the front end of the drive shaft 34 a and a second spur gear 36 provided at the rear end of the control shaft 32. To communicate.
In this embodiment, a hydraulic actuator is used as the actuator 34, but a step motor can be used.

The hydraulic actuator 34 includes a hydraulic operation unit 61 and a solenoid-type flow path switching valve 60, and the flow path switching valve 60 supplies hydraulic pressure to the hydraulic operation unit 61 based on a control signal from the control unit 37. By switching the drain, the hydraulic operation unit 61 drives the angle of the control shaft 32 to a target angle position corresponding to the target operating angle.
On the other hand, as shown in FIG. 1, the center phase variable mechanism 2 includes a timing sprocket 40 that rotates in synchronization with the crankshaft transmitted from the crankshaft of the engine by a timing chain (not shown), and a drive shaft 13. A sleep 42 fixed in the axial direction by a bolt 41 at the front end portion thereof, a cylindrical gear 43 interposed between the timing sprocket 40 and the sleep 42, and the cylindrical gear 43 in the longitudinal axis direction of the drive shaft 13 And a hydraulic circuit 44 which is a drive mechanism for driving the

The timing sprocket 40 includes a cylindrical main body 40a and a sprocket portion 40b fixed to a rear end portion of the cylindrical main body 40a by a bolt 45, and a front end opening of the cylindrical main body 40a is closed by a front cover 40c. .
Further, helical inner teeth are formed on the inner peripheral surface of the cylindrical main body 40a.
The sleep 42 is formed with a fitting groove into which the tip end of the drive shaft 13 is fitted on the rear end side, and a coil spring 47 that urges the timing sprocket 40 forward through the front cover 40c at the front end portion. Is installed.

Further, on the outer peripheral surface of the sleep 42, a helical outer tooth 48 is formed.
The cylindrical gear 43 is divided into two from the direction perpendicular to the axis, and the front and rear gear components are urged toward each other by pins and springs, and the inner and outer peripheral surfaces mesh with the inner teeth 46 and the outer teeth 48. The internal and external teeth of a helical tooth shape are formed and move in the longitudinal axis direction while sliding between the teeth by the hydraulic pressure supplied relatively to the first and second hydraulic chambers 49 and 50 formed in the front and rear. It is supposed to be.

Further, the cylindrical gear 43 controls the intake valve 12 to the most retarded position at the maximum forward movement position where it hits the front cover 40c, while controlling the intake valve 12 to the most advanced position at the maximum rearward movement position. Yes.
Further, when the hydraulic pressure of the first hydraulic chamber 49 is not supplied by the return spring 51 mounted in the second hydraulic chamber 50, the maximum hydraulic position is urged.

The hydraulic circuit 44 includes a main gallery 53 for the oil pump 52, and first and second hydraulic passages 54 and 55 that are branched downstream of the main gallery 53 and connected to the first and second hydraulic chambers 49 and 50. The solenoid-type flow path switching valve 56 provided at the branch position and the drain passage 57 connected to the flow path switching valve 56 are configured.
The flow path switching valve 56 is switched and driven by a control signal from the control unit 37.

However, the center phase variable mechanism 2 only needs to be a mechanism that makes the rotational phase of the drive shaft 13 variable with respect to the crankshaft, and various known mechanisms such as a mechanism using an electromagnetic brake in addition to a hydraulic type can be adopted.
Thus, in this embodiment, the lift / operating angle variable mechanism 1 and the center phase variable mechanism 2 share the oil pump 52 that is a drive source.

The control unit 37 is configured to include a microcomputer, and based on detection signals from various sensors such as an engine rotation signal from the crank angle sensor 101, an intake flow signal (load) from the air flow meter 102, and a water temperature sensor 103. The engine operating state is detected by calculation or the like.
Further, the lift / operating angle variable mechanism 1 is controlled by outputting a control signal to the flow path switching valve 60 based on a signal from the first position detection sensor 58 that detects the current rotational position of the control shaft 32, A relative rotational phase difference between the drive shaft 13 and the crankshaft is calculated from a signal from the second position detection sensor 59 for detecting the rotational position of the drive shaft 13 and a signal from the crank angle sensor 101, and the rotational position is calculated. The center phase variable mechanism 2 is controlled by outputting a control signal to the flow path switching valve 56 based on the phase difference.

  That is, the control unit 37 sets the target value TGVEL of the operating angle of the intake valve 12 based on information such as the engine speed, load, and water temperature, and sets the target angular position of the control shaft 32 corresponding to the target value TGVEL. Based on the actual angular position of the control shaft 32 detected by the first position detection sensor 58, the command signal is feedback controlled to the flow path switching valve 60.

Similarly, the control unit 37 sets the target value TGVTC of the central phase of the operating angle of the intake valve 12 based on information such as the engine speed, load, and water temperature, and the second position detection sensor 59 and the crank angle sensor. Based on the actual center phase detected based on 101 and the target value TGVTC, the command signal is feedback-controlled to the flow path switching valve 56.
FIG. 4 shows how the valve lift characteristics are changed by the lift / operating angle variable mechanism 1 and the center phase variable mechanism 2.

As shown in the figure, when the lift / operating angle variable mechanism 1 is driven, the operating phase of the intake valve 12 is maintained while the center phase of the operating angle of the intake valve 12 remains substantially constant, as shown by an arrow (A). Both the valve lift and the valve lift continuously increase and decrease.
On the other hand, when the center phase variable mechanism 2 is driven, as shown by an arrow (b), the operation angle and the valve lift amount of the intake valve 12 remain constant, and the center phase of the operation angle of the intake valve 12 is advanced or retarded. Move to the corner.

  As described above, the control unit 37 performs drive control of the lift / operation angle variable mechanism 1 based on the target value TGVEL and drive control of the center phase variable mechanism 2 based on the target value TGVTC. 5, the cooperative control function, which is a function for limiting the operation of the lift / operating angle variable mechanism 1 (the operating angle of the intake valve 12) in the process in which the center phase of the intake valve 12 converges toward the target, As shown in the flowchart, it is provided as software.

In the flowchart of FIG. 5, in step S <b> 1, based on the target value TGVTC of the center phase of the intake valve 12, the second position detection sensor 59, and the crank angle sensor 101, whether or not the condition for cooperative control is necessary. Judgment is made based on whether or not the absolute value of the deviation from the actual center phase REALVTC detected in this way is greater than or equal to a predetermined value.
The target value TGVTC of the center phase and the actual center phase REALVTC are expressed as, for example, an angle from a reference position set before the top dead center to the center position of the operating angle.

If | TGVTC-REALVTC | ≧ predetermined value, that is, if the center phase variable mechanism 2 is not converging near the target and is changing toward the target, it is determined that cooperative control is necessary, Proceed to step S2.
On the other hand, if | TGVTC−REALVTC | <predetermined value, that is, if the center phase variable mechanism 2 is converged near the target, it is determined that the cooperative control is unnecessary, and the process proceeds to step S3.

When it is determined that cooperative control is necessary, the process proceeds to step S2, and the actual center phase REALVTC at that time is selected as the center phase used when calculating an operating angle limit value LIVEL described later.
On the other hand, when it is determined that the cooperative control is unnecessary and the process proceeds to step S3, the target value TGVTC is selected as the center phase used when calculating the operating angle limit value LIVEL described later.

In step S4, from the center phase selected in step S2 or step S3 (the crank angle that is the center of the operating angle) and the target value TGVEL and the target value TGVTC, the target opening timing IVO of the intake valve 12 is obtained. The operating angle limit value LIVEL is calculated as “operating angle limit value LIVEL = (selected center phase−target opening timing IVO) × 2”.
That is, when it is determined that cooperative control is necessary, the operating angle A calculated as “operating angle A = (actual center phase REALVTC−target opening timing IVO) × 2” is set to the limit value LIVEL, and the cooperative control is performed. Is determined to be unnecessary, the operating angle B calculated as “operating angle B = (target value TGVTC−target opening timing IVO) × 2” is set to the limit value LIVEL.

Here, since the operating angle B corresponds to the required operating angle in the lift / operating angle variable mechanism 1, when the limiting value LIVEL = the operating angle B, the limiting value LIVEL is set. In practice, the operating angle is not limited.
In parallel with the calculation process of the operating angle limit value LIVEL, the operating angle B is calculated in step S5.

In step S6, it is determined whether or not a condition that causes overcorrection by cooperative control.
In step S6, it is determined whether or not the operating angle B ≧ the limit value LIVEL, and whether or not the previous value of the operating angle (operating angle C) as a result of the cooperative control> the limit value LIVEL is determined. To do.
Here, the operating angle B ≧ the limit value LIVEL represents an acceleration state in which the operating angle needs to be limited to be small in response to a request for increasing the operating angle, and the operating angle C> the limit value LIVEL is equal to the limit value LIVEL. It represents that the operating angle is changed in the direction of decreasing.

When the limit by the limit value LIVEEL is applied when the operating angle B ≧ the limit value LIVEL and the operating angle C> the limit value LIVEL, the operating angle is decreased and changed in response to the request for increasing the operating angle. It will be determined that an overcorrection will occur.
On the other hand, when the operation angle B <the limit value LIVEL and / or the operation angle C ≦ the limit value LIVEL, it is determined that no overcorrection (operation angle change in the direction opposite to the request) occurs.

If it is determined that overcorrection will occur, the process proceeds to step S7, where the operating angle B and the operating angle C are compared, and the smaller operating angle is selected.
On the other hand, when it is determined that no overcorrection occurs, the process proceeds to step S8, and the limit value LIVEL obtained in step S4 is selected as it is.
In step S9, the operating angle set in step S7 or step S8 is compared with the operating angle B.

If “the operating angle set in step S7 or step S8” ≦ the operating angle B, the process proceeds to step S10, and the operating angle set in step S7 or step S8 is set to the target value TGVEL. Then, a target value limiting process is performed in which the normal target value is replaced with the operating angle set in step S7 or step S8.
On the other hand, if “the operating angle set in step S7 or step S8”> the operating angle B, the process proceeds to step S11, and the operating angle B is set to the target value TGVEL. Target value.

  For example, when increasing the lift / operating angle of the intake valve 12 at the same time as retarding the opening timing IVO of the intake valve 12 with acceleration, the center phase is delayed by the center phase variable mechanism 2. If the increase in the lift / operation angle is too early, the opening timing IVO should be gradually changed gradually, but the opening timing IVO may be changed in the middle.

Therefore, basically, the target operating angle is limited to the operating angle A or less so that the operating angle A = (actual center phase REALVTC−target opening timing IVO) × 2 is not controlled. Thus, the actual opening timing IVO is not advanced from the target opening timing IVO (see FIG. 6).
Therefore, even if the delay control of the center phase by the center phase variable mechanism 2 and the increase control of the lift / operation angle by the lift / operation angle variable mechanism 1 are performed simultaneously, The opening timing IVO does not change in a direction that is earlier than the target, and the valve overlap is increased by increasing the opening timing IVO illegally.・ It is possible to prevent the increase in operating angle from being greatly delayed and the drivability during transition to decline.

However, as described above, as a result of limiting the operating angle to the limit value or less, there is a possibility that the operating angle may be temporarily limited to be smaller than before the start of acceleration even when the increase of the operating angle accompanying acceleration is requested. (See FIG. 7).
Therefore, a state in which the operating angle is temporarily limited to be smaller than before the start of acceleration is determined as an overcorrected state.

Here, if overcorrection does not occur, the process proceeds to step S8, and the limitation of the operating angle based on the limit value LIVEL calculated in step S4 is executed as it is. However, if overcorrection occurs, the process proceeds to step S7. Proceeding and selecting the smaller of the operating angle B and the operating angle C, as a result, the operating angle before the start of acceleration is held as the limit value LIVEL (see FIG. 7).
Therefore, in response to a request to increase the lift / operating angle of the intake valve 12 due to acceleration, it is possible to prevent the lift / operating angle from being decreased and changed to prevent the torque from being decreased. It is possible to minimize fraud in the IVO.

1 is a schematic configuration diagram showing a variable valve control apparatus for an internal combustion engine according to an embodiment of the present invention. AA sectional drawing of FIG. FIG. 2 is a plan view showing the lift / operating angle variable mechanism of FIG. 1. The characteristic view which shows the change of the valve lift characteristic by the lift, working angle variable mechanism, and center phase variable mechanism of embodiment. The flowchart which shows the cooperative control in embodiment. The figure which shows the correlation with the operating angle and center phase in embodiment. The time chart which shows the state of overcorrection in the embodiment, and the correction state of overcorrection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lift / operating angle variable mechanism, 2 ... Center phase variable mechanism, 12 ... Intake valve, 13 ... Drive shaft, 32 ... Control shaft, 34 ... Actuator, 37 ... Control unit, 52 ... Oil pump

Claims (2)

A lift and operating angle variable mechanism for changing the lift and operating angle of the intake valve; and a center phase variable mechanism for changing the center phase of the operating angle of the intake valve;
The lift and operating angle target values and the center phase target value are calculated based on the engine operating state, respectively, and the lift and operating angle variable mechanism and the center phase variable mechanism are controlled based on the target values. A variable valve controller for an internal combustion engine,
In the process in which the center phase of the operating angle of the intake valve changes toward the target value by the center phase variable mechanism, the opening timing of the intake valve becomes the target opening timing with the actual value of the center phase at that time. While limiting the operating angle by the lift and the operating angle variable mechanism to the upper limit value or less with the operating angle as the upper limit value, the opening timing of the intake valve is limited to advance change ,
When the operating angle is limited based on the upper limit value, the operating angle of the intake valve is held at the previous value when the operating angle is decreased and changed in response to a request to increase the operating angle . Variable valve control device.   2. The determination as to whether the center phase is a process of changing the retardation toward the target value based on a deviation between the target value of the center phase and an actual center phase at that time. The variable valve control apparatus for an internal combustion engine according to claim.

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