JP2004011590A - Variable valve control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable keeping valve timing before/after switching a cam in a VVL device, in the case that a valve timing variable device (a VTC device) by rotation phase controlling and a valve lift variable device (a VVL device) by cam switching are provided. <P>SOLUTION: In the VVL device, when cam switching from a low lift to a high lift is carried out, a control gain for controlling the VTC device is changed to a large value for the high lift (S2, S4, S5). Conversely, when cam switching from the high lift to the low lift is carried out, the control gain for controlling the VTC device is changed to be a small value for the low lift (S3, S6, S7). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a variable valve control device for an engine having a variable valve timing device (VTC device) and a variable valve lift device (VVL device).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a variable valve operating device for an engine, a valve timing variable device that changes a valve timing by changing a rotation phase between a crankshaft and a camshaft as described in Japanese Patent Application Laid-Open No. 2000-18056. And a variable valve lift device that changes a valve lift amount by selectively switching a plurality of cams having different cam profiles on a camshaft.
[0003]
In this device, when the valve lift is changed and the target value of the valve timing is largely changed, the output torque of the engine is prevented from dropping. The response speed of the change is increased to make the response follow well.
[0004]
[Problems to be solved by the invention]
However, the above publication presupposes that the valve timing is changed when the valve lift amount is changed by the variable valve lift device, and that the valve timing is held before and after the change in the valve lift amount, that is, before and after the cam switching. I don't consider anything to do.
[0005]
When the valve lift amount is changed by the variable valve lift device, if the valve timing is to be maintained before and after the change of the valve lift amount, even if the control output to the variable valve timing device is kept constant, the cam switching is performed. In addition, there is a problem that the actual valve timing is deviated from the target valve timing by an amount corresponding to the change in the cam driving torque, so that the actual valve timing is not stabilized.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its object to be able to hold a valve timing before and after a change in a valve lift amount when a valve lift amount is changed by a variable valve lift device. I do.
[0007]
[Means for Solving the Problems]
For this reason, according to the present invention, the control gain for controlling the rotation phase of the variable valve timing device includes a first gain for maintaining a predetermined rotation phase by a cam before switching, and a predetermined gain for controlling the rotation phase by the cam after switching. Is stored in advance. Then, when the switching of the cam by the variable valve lift device is detected, the control gain is changed from the first gain to the second gain.
[0008]
【The invention's effect】
According to the present invention, when the cam is switched by the variable valve lift device, the control gain for controlling the rotational phase of the variable valve timing device is changed from the first gain to the second gain. Even if the fluctuation of the torque increases, the control can be stabilized by changing the control gain.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of a variable valve control device for an engine according to an embodiment of the present invention.
The camshaft 10 is provided with a low-lift low cam 11 and a high-lift high cam 12 sandwiching the low cam 11 for each valve (intake / exhaust valve) 20 driven thereby. FIG. 2 shows examples of the cam profiles of the low cam 11 and the high cam 12.
[0010]
The valve lifter of the valve 20 has a double cylinder structure of an inner cylinder 21 and an outer cylinder 22, and the inner cylinder 21 is integral with the valve stem. Although the outer cylinder 22 is slidable with respect to the inner cylinder 21, the inner cylinder 21 and the outer cylinder 22 can be integrated by a lock pin (not shown).
Here, the low cam 11 faces the end face of the inner cylinder 21, and the high cam 12 faces the end face of the outer cylinder 22.
[0011]
Therefore, when the inner cylinder 21 and the outer cylinder 22 are not integrated, the valve 20 is driven by the low cam 11 via the inner cylinder 21. On the other hand, when the inner cylinder 21 and the outer cylinder 22 are integrated by the lock pin, the valve 20 is driven by the high cam 12 having a large lift through the outer cylinder 22 → the lock pin → the inner cylinder 21.
The lock pin is controlled by hydraulic pressure supplied to a hydraulic port 23, and the hydraulic pressure is controlled by a solenoid valve (hereinafter, referred to as a VVL solenoid) 25 upstream of an oil supply passage 24.
[0012]
Accordingly, the signal from the control unit 100 controls the hydraulic pressure by turning the VVL solenoid 25 ON or OFF, and switches the state of the lock pin, thereby selectively switching the low cam 11 or the high cam 12 and thereby controlling the valve lift. The amount can be changed, thereby forming a variable valve lift device (hereinafter referred to as VVL device).
[0013]
On the other hand, the camshaft 10 is driven by the rotation of a crankshaft (not shown) being input to the sprocket 13 by a timing belt, and is driven between the sprocket 13 and the camshaft 10 by a rotary solenoid (which can control the rotation phase thereof). (Hereinafter referred to as a VTC solenoid) 14 is mounted.
Accordingly, the duty from the VTC solenoid 14 is controlled by a signal from the control unit 100 to change the rotational phase between the crankshaft and the camshaft, thereby changing the valve timing. A variable device (hereinafter, referred to as a VTC device) is configured.
[0014]
The control unit 100 receives a signal from a crank angle sensor 31 that detects the rotation angle of the crankshaft and a signal from a cam angle sensor 32 that can detect the rotation angle of the camshaft. In addition, as the operating state of the engine, the engine speed Ne can be detected based on a signal from the crank angle sensor 31. In addition, detection signals such as an intake air amount Qa, a throttle opening TVO, and a water temperature Tw are output from various sensors. Has been entered.
[0015]
The control unit 100 controls the valve lift by controlling ON / OFF of the VVL solenoid 25 based on these detection signals, and controls the valve timing by controlling the duty of the VTC solenoid 14.
Here, the duty control of the VTC solenoid 14, particularly the setting of the control gain, will be described with reference to the flowchart of FIG.
[0016]
In S1, a duty (VTC duty) to the VTC solenoid 14 is calculated. This is done as shown in the control block diagram in FIG.
That is, referring to FIG. 4, at 101, a VTC target phase is set based on the operating state of the engine, and at 102, a deviation from the VTC actual phase (detectable by the cam angle sensor) is calculated.
[0017]
With respect to this deviation, a proportional gain Pk for proportional control is given at 103 and an integral gain Pi for integral control is given at 104 as control gains, and the proportional component and the integral component are added at 105 at 105 Then, the VTC duty is calculated at 106 based on the added value.
In S2, it is determined whether or not the valve lift has been switched from a low lift to a high lift in the VVL device. When the VVL solenoid turns on and the lift is high, VVL solenoid OFF → ON is detected. Conversely, when the VVL solenoid turns on and the lift is low, VVL solenoid ON → OFF is detected. This portion corresponds to cam switching detection means.
[0018]
In S3, it is determined whether or not the valve lift has been switched from a high lift to a low lift in the VVL device. When the VVL solenoid is ON and the lift is high, the VVL solenoid ON → OFF is detected. Conversely, when the VVL solenoid is ON and the lift is low, the VVL solenoid OFF → ON is detected. This portion also corresponds to the cam switching detection means.
[0019]
If it is determined in S2 that the valve lift has been switched from low to high in the VVL device, the process proceeds to S4.
In S4, it is determined whether or not the current VTC control gains (proportional gain and integral gain) Pk, Pi are set to relatively small values k1, i1 for a low lift. In the case of YES, the process proceeds to S5. , VTC control gains Pk and Pi are switched to relatively large values k2 and i2 for high lift (k2> k1, i2> i1).
[0020]
In this case, k1 and i1 are the first gains for maintaining a predetermined rotation phase by the driving torque of the low-lift cam before the cam switching, and the rotation phase before the cam switching by the driving torque of the high-lift cam after the cam switching. This means that k2 and i2 are stored as the second gain to be held, and when the cam switch from low lift to high lift is detected, the control gain is changed from the first gain k1 and i1 to a relatively large second gain. Change to k2, i2. Therefore, this part corresponds to gain changing means.
[0021]
If it is determined in S3 that the lift amount has been switched from the high lift to the low lift in the VVL device, the process proceeds to S6.
In S6, it is determined whether or not the current VTC control gains Pk, Pi are set to relatively large values k2, i2 for a high lift. If YES, the process proceeds to S7, in which the VTC control gains Pk, Pi are determined. To a relatively small value k1, i1 for low lift.
[0022]
In this case, k2 and i2 are used as the first gain for maintaining a predetermined rotation phase by the driving torque of the high lift cam before the cam switching, and the rotation phase before the cam switching is changed by the driving torque of the low lift cam after the cam switching. This means that k1 and i1 are stored as the second gain to be held, and when the cam switching from high lift to low lift is detected, the control gain is changed from the first gain k2 and i2 to a relatively small second gain. Change to k1 and i1. Therefore, this part also corresponds to gain changing means.
[0023]
Note that the control gains k1 and i1 for the low lift and the control gains k2 and i2 for the high lift may be given as constants, respectively, but each is obtained by a map using the engine operating state (Ne, Qa or TVO) as a parameter. May be given.
Next, the operation will be described with reference to FIGS.
As shown in FIG. 5, in a VVL device in which the valve lift characteristic becomes high lift when the VVL solenoid is turned on, when the VVL solenoid is switched from OFF to ON, the valve lift characteristic changes to high lift, and the fluctuation of the cam driving torque becomes large. , VTC control becomes unstable. In other words, when the control gain is changed to the high lift and the control gain adapted to the low lift remains small, the deviation of the actual phase from the VTC target phase becomes large as shown by the dotted line. Therefore, when switching the VVL solenoid from OFF to ON, that is, when switching from low lift to high lift, the VTC control gain can be increased to stabilize VTC control.
[0024]
As shown in FIG. 6, in the VVL device in which the valve lift characteristic is low when the VVL solenoid is ON, the valve lift characteristic changes to low lift when the VVL solenoid is switched from OFF to ON. , VTC control becomes unstable. In other words, if the control gain is adjusted to the high lift when the lift is changed to the low lift, the actual phase shift from the VTC target phase becomes large as shown by the dotted line. Therefore, when the VVL solenoid is switched from OFF to ON, that is, when the lift is switched from high lift to low lift, the VTC control gain can be reduced to stabilize VTC control.
[0025]
According to the present embodiment, when the cam is switched by the VVL device, the control gain for controlling the rotation phase of the VTC device is changed from the first gain to the second gain, so that the valve lift characteristic changes and the cam drive torque varies. Control becomes stable by changing the control gain.
Further, according to the present embodiment, when switching from a cam having a small lift amount to a cam having a large lift amount in the VVL device, the second gain is made larger than the first gain so as to reliably cope with stabilization of control. Can be.
[0026]
Further, according to the present embodiment, when switching from a cam having a large lift amount to a cam having a small lift amount in the VVL device, the second gain is made smaller than the first gain so as to reliably cope with the stabilization of control. Can be.
[Brief description of the drawings]
FIG. 1 is a system diagram of a variable valve control device showing an embodiment of the present invention. FIG. 2 is a diagram showing an example of a cam profile of a low cam and a high cam. FIG. 3 is a flowchart of VTC control. FIG. Control block diagram [Fig. 5] Control characteristic diagram when switching from low lift to high lift [Fig. 6] Control characteristic diagram when switching from high lift to low lift [Explanation of reference numerals]
Reference Signs List 10 Camshaft 11 Low cam 12 High cam 13 Sprocket 14 VTC solenoid 20 Valve 21 Inner cylinder 22 Outer cylinder 23 Lock pin control hydraulic port 24 Oil supply passage 25 VVL solenoid 31 Crank angle sensor 32 Cam angle sensor 100 Control unit 103 Proportional gain applying unit 104 Integral gain application section

Claims (3)

A variable valve timing device that changes the valve timing by changing the rotation phase between the crankshaft and camshaft according to the signal from the control unit, and a cam with multiple different cam profiles on the camshaft according to the signal from the control unit A variable valve lift control device for an engine, comprising:
Detecting means for detecting cam switching by the variable valve lift device;
As a control gain for controlling the rotation phase of the variable valve timing device, a first gain for holding a predetermined rotation phase by a cam before switching and a second gain for holding the predetermined rotation phase by a cam after switching Storage means for storing
Gain changing means for changing the control gain from the first gain to the second gain when the detection means detects the switching of the cam;
A variable valve control apparatus for an engine, comprising: 2. The variable valve control apparatus for an engine according to claim 1, wherein when switching from a cam having a small lift to a cam having a large lift with the variable valve lift, the second gain is made larger than the first gain. . 3. The engine according to claim 1, wherein the second gain is smaller than the first gain when switching from a cam having a large lift to a cam having a small lift with the variable valve lift device. Variable valve control device.

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