JPH0658235A - Intake/exhaust valve lift control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To favorably maintain the combustion condition of an engine even on the way of changeover of lift characteristics by controlling lift characteristics such as lift quantities of intake/exhaust valves or timing of opening/closing according to the operating condition of the engine. CONSTITUTION:This intake/exhaust valve lift control device is provided with opening/closing drive means 41, 43, 45 to synchronize with the engine speed and drive to open/close intake/exhaust valves 42, and lift characteristics changing means 50, 51, 56 to change over the operating conditions of the opening/ closing drive means 41, 43, 45 and change the lift characteristics of the intake/ exhaust valves 42. Further, it is provided with a first control means 57 to control the lift characteristics changing means 50, 51, 56 so as to conform target characteristics to real characteristics, and a second control means 57 to control physical quantity such as ignition timing concerning combustion of the engine based on the output of an operating condition detecting means and the real lift characteristics. Hereby, the engine can be accurately controlled according to the changed valve lift characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust valve lift control device for an internal combustion engine, and more specifically, to optimally control so-called lift characteristics such as intake / exhaust valve lift amounts and opening / closing timings in accordance with engine operating conditions. The present invention relates to an intake / exhaust valve lift control device for an internal combustion engine.

[0002]

2. Description of the Related Art As a conventional intake / exhaust valve lift control device, for example, those shown in FIGS. 11 to 15 are known (for reference, see, for example, Japanese Utility Model Laid-Open No. 59-141170.
There is a gazette). To outline this device, in FIG. 11, 1 is a cylinder block, 2 is a cylinder head, 3 is a piston, 4 is a crankshaft, and a timing pulley 5 is fixed to one end of the crankshaft 4.
It is connected to a timing pulley 8 provided at one end of the cam shaft 7 via a timing belt 6.

Reference numeral 9 is a main body 9A and a distributor shaft 9B.
The distributor shaft 9B is meshed with the cam shaft 7 by a gear (not shown). A breaker plate is provided in the main body 9A and is connected to the advance angle control negative pressure actuator 10. The negative pressure actuator 10 is a two-stage diaphragm type, and one negative pressure chamber 10A communicates with an intake passage 13 slightly upstream of the throttle valve 12 via a negative pressure pipe 11 to perform negative pressure advance control.

Between the timing pulley 8 and the cam shaft 7 on the cam shaft 7, there is provided a valve timing control device for controlling the rotational phase of the cam shaft 7 with respect to the crank shaft 4 as shown in FIGS. 12 and 13. Has been. In FIG. 12 and FIG. 13, 21 is a stepping motor, and when the motor 21 is rotated in the normal or reverse direction, the rotational movement of the output shaft 22 thereof is
The threaded portion converts the linear movement of the drive nut 23, whereby the bearing support 24 moves left and right in FIG. 12 according to the rotation direction of the motor 21. The left and right movements of the bearing support 24 are transmitted to the bearing 2 via the shaft portion 25.
The bearings 26, 27 are transmitted to the bearings 6, 27, and move in the direction of arrow A in FIG. 13 while rolling in the slits 28, 29 arranged in a cross arrangement. As a result, relative rotation occurs between the outer sleeve 30 and the inner sleeve 31, the relative angular position between the crankshaft 4 and the camshaft 7 changes, and the lift characteristics of the intake / exhaust valve are changed.

From the control circuit 32, as shown in FIG.
Engine operating range (valve timing switching diaphragm
Signal for switching the valve timing according to the
(B)) is output at the same time. Low level period of this signal
The period corresponds to the normal rotation period of the motor 21, and is the high level period.
Corresponds to the reverse rotation operation period of the motor 21. That is,
The three-way switching valve 33 operates in synchronization with the forward / reverse rotation of the motor 21.
(Fig. 11, Fig. 15 (b)). For example,
During the low level period, the three-way switching valve 33
Negative pressure is introduced into the negative pressure chamber 10B of the
So that the breaker plate 9C of the
The advance angle control shaft 34 of the actuator 10 is moved to the left in Fig. 11.
Sent. Angular position of breaker plate 9C at this time
Is θ₁It is represented by. Also, blurring during the high level period
The position of the marker plate 9C is θ₂Represented by (in Fig. 15
(C)). Such a rotational displacement of the breaker plate 9C
Δθ is the relative rotational movement of the cam shaft 7 with respect to the crank shaft 4.
(That is, change operation of lift characteristics of intake / exhaust valve)
However, the ignition timing may vary due to valve timing switching.
Not ((d) in Figure 15). Further, the diaphragms 35 and 36 shown in FIG.
Switching time lag L ₁, L₂((B) in Figure 15)
In addition, the negative pressure or the introduction speed of the atmosphere is shown in (c) of FIG.
m₁, M₂It is regulated like
Therefore, the deviation of the ignition timing is eliminated.

[0006]

However, in such a conventional intake / exhaust valve lift control device, when the lift characteristic is changed by the motor 21, the ignition timing is changed by simultaneously switching the three-way switching valve 33. However, since the motor 21 and the three-way switching valve 33 have different responsiveness and operating speed, for example, there is a problem that the lift characteristic and the ignition timing are deviated during switching.

Therefore, an object of the present invention is to maintain a good combustion state of the engine even during the switching of the lift characteristics.

[0008]

In order to achieve the above-mentioned object, the present invention comprises an operating condition detecting means for detecting an operating condition of an engine, and an intake port or an exhaust port, as shown in FIG. An intake / exhaust valve that opens and closes, and an opening and closing drive means that opens and closes the intake and exhaust valve in synchronization with engine rotation,
Lift characteristic change means for changing the lift characteristic of the intake / exhaust valve by switching the operation mode of the opening / closing drive means, and target lift characteristic setting means for setting the target lift characteristic of the intake / exhaust valve according to the operating state of the engine. A first lift characteristic changing means for detecting a state quantity related to an actual lift characteristic of the intake / exhaust valve, and a first lift characteristic changing means for controlling the target lift characteristic and the actual lift characteristic to coincide with each other. And a second control means for controlling a physical quantity involved in combustion of the engine based on the output of the operating state detecting means and the output of the actual lift characteristic detecting means.

[0009]

In the present invention, the combustion parameters of the engine (for example, ignition timing and fuel supply amount) are controlled in consideration of the actual lift characteristics of the intake and exhaust valves. Therefore, for example, without being influenced by the variation in the switching responsiveness of each product caused by the variation in the clearance of the rotary sliding portion in the lift characteristic changing unit, or the change in the engine temperature, the rotational speed, etc. The engine control can be accurately performed according to the valve lift characteristics that are actually switched, without being affected by the variation in switching responsiveness of one product that occurs due to the change.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 2 to 10 are views showing an embodiment of the present invention. First, the structure will be described. The intake / exhaust valve lift variable mechanism includes, as shown in FIG. 2, a drive cam 41 fixed to a cam shaft 41A that rotates in synchronization with engine rotation, an intake / exhaust valve (hereinafter, The rocker arm 43 is provided by contacting both ends with the stem end of the intake valve 42, and the curved rear surface 43a of the rocker arm 43 is brought into fulcrum contact with the rocker arm 43.
A lever 45 is provided for holding the shaft 43b protruding from both side walls of 43 in the groove 45a via the holding member 44.
The cam shaft 41A is connected to a distributor shaft of a distributor 74 described later. Between the spring seat 45b formed on the lever 45 and the holding member 44,
A spring 46 having a small spring constant is interposed to urge the rocker arm 43 downward in FIG.

Further, the spherical lower end surface of the hydraulic pivot 49 fitted and held in the bracket 48 interposed in the cylinder head 47 has a recess formed in the top wall of the lower end portion of the lever 45 on the stem end side of the intake valve 42. The bracket 45 is fitted to the portion 45c to support the lever 45 so that the lever 45 can swing freely around the fitting portion.
A lift control cam 50, which is rotatably attached to the shaft 48, comes into contact with the top wall of the end portion of the lever 45 on the drive cam 41 side to regulate the swing amount of the lever 45, as described later. The drive cam 41, the rocker arm 43, the lever 45, and the components attached to them together form an opening / closing drive means for driving the intake valve 42 to open / close in synchronization with the engine rotation. Here, the lift control cam 50 includes a cam control shaft 51 and an actuator 56, which will be described later.
At the same time, it has a function as a lift characteristic changing means for changing the lift characteristic of the intake valve 42, and five substantially flat cam surfaces 50a to 50e having different heights (cam radii) are formed on the outer peripheral surface thereof. And a cam control shaft 51 described later in the center.
It has a hole 50g for inserting.

The lower end surface of the hydraulic pivot 49 is the lever.
It fits in the recessed part 45c of 45, and the peripheral surface is the bracket 48.
An outer cylinder 49 slidably inserted in the mounting hole 48a formed in
a and an inner cylinder 49b fitted into the outer cylinder 49a, and a check valve is provided in a hydraulic chamber 49c formed between the two.
It is formed with 49d. Then, the hydraulic pressure is supplied from the hydraulic pressure supply passage 48b formed inside the bracket 48 to the hydraulic chamber 49c through the inside of the inner cylinder 49b and the check valve 49d to keep the valve clearance at zero.

An outer peripheral surface of a cylindrical portion 50h formed so as to project from both sides of the lift control cam 50 has a lower arc groove 48c formed in a bracket 48 as shown in FIGS.
A pair of caps fastened on the bracket 48 with bolts 52
It is rotatably held between the upper circular arc groove 53a formed in 53. Then, the lift control cam 50 provided with several cylinders
One cam control shaft 51 is passed through a hole 50g formed through the central portion of the cam control shaft 51, and one end of a coil spring 54 is inserted into each side portion of each lift control cam 50 of the cam control shaft 51. 51 It is locked to a set screw 51a screwed into the outer wall, and the other end of the coil spring 54 is lifted by a lift control cam 50.
It is fitted and locked in the hole formed in the side wall of the cylindrical portion 50h.

One end of the cam control shaft 51 is connected to a drive shaft 56a of an actuator 56 (eg stepping motor) via a joint 55. The actuator 56 rotates the cam control shaft 51 in the forward and reverse directions by a designated amount in accordance with the drive signal SK from the control circuit 57, and switches the operation mode of the lift control cam 50, that is, the cam surface, to lift the intake valve 42. To change. Reference numeral 58 is a valve spring, and 69 is a potentiometer described later. The potentiometer 69 is a rotary position of the drive shaft 56a of the actuator 56, in other words, a lift control cam 50 connected to the drive shaft 56a. The rotational position, or in other words "5 cam faces 50
It outputs an electric signal (CP) representing a state quantity related to the actual lift characteristic of the intake valve 42, such as "which cam surface is switched among a to 50e". Therefore, the potentiometer 69 has a function as an actual lift characteristic detecting means.

Next, the structure of the control circuit 57 will be described with reference to FIG. The control circuit 57 is a target lift characteristic setting unit,
It has a function as a first control unit, a second control unit, and an abnormality determination unit, and has a central processing unit CPU 60, a read-only memory ROM 6, a random access memory RAM.
62 and an I / O port (input / output signal processing device) 63. The CPU 60 executes the program written in the ROM 61 at processing steps in synchronization with the clock 64, fetches external data required from the I / O port 63, and exchanges data with the RAM 62 via the bus line 65. A necessary processing value is calculated while performing the calculation via the I / O port 63, and the calculation result is output from the I / O port 63 at a predetermined timing.

Here, the engine speed NE is detected by, for example, the crank angle sensor 66 as a speed signal, and the crank angle top and bottom dead center position KP is as a top and bottom dead center position reference signal (hereinafter referred to as a reference signal). Each is taken in from the I / O port 63. Further, the opening CV of the throttle valve is detected by the throttle valve opening sensor 67, converted into a digital signal by the A / D converter 68, and then, as the throttle valve opening signal, the rotational position CP of the cam control shaft 51 is calculated. It is detected by the potentiometer 69, converted into a digital signal by the A / D converter 70, and then _{fetched from} the I / O port 63 as the actual position signal V _fth . Further, an operation / non-operation signal SA for detecting the operation / non-operation of the actuator 56 is fetched from the I / O port 63 via the drive circuit 71.

The crank angle sensor 66 and the throttle valve opening sensor 67 constitute the engine operating condition detecting means as a whole, and the control circuit 57 controls each signal from the operating condition detecting means and the operation from the actuator 56.・ Non-operation signal SA
And the actual position signal V _fth of the cam control shaft 51,
Calculate the control value (rotation amount and rotation direction of the cam control shaft 51),
The intake / exhaust valves so that the cam surfaces 50a to 50e become the predetermined target cam surfaces, that is, according to the operating state of the engine at that time.
The drive signal SK is output to the actuator 56 via the drive circuit 71 so that the target cam surface required to obtain the target lift characteristic of 42 is obtained. When it is determined that a failure has occurred, the control circuit 57 outputs the alarm signal SB to the alarm 72 and activates the alarm 72.

Further, the fuel injection valve 73 is controlled by the injection signal SF having a predetermined pulse width (energization time) controlled by the reference signal, and the ignition coil 75 connected to the distributor 74 is also controlled by the reference signal. The ignition signal ST is output according to the predetermined ignition timing. Next, the operation will be described.

FIG. 6 shows the cam surface written in the ROM 61.
A control program for selecting control 50 a to 50 e, also, FIG. 7 is a flowcharts showing respectively a control program for controlling the ignition timing, in the drawing P ₁ to P ₄₆ represents the steps of the flowchart. These programs are executed, for example, once every one revolution of the engine. First,
In P ₁ to P _9, as shown in FIG. 8, whether or not (the i 0 to 5) each operating region POSi set from the relationship between the opening CV and the engine speed NE of the throttle valve is in one of the To determine.

P ₁ : The throttle valve opening CV is less than a predetermined value A ₁ (for example, A ₁ = 2 °) corresponding to idling, or P ₂ : the rotational speed NE is a predetermined value E ₀ and a predetermined value E. it is in idling rotation speed range between (e.g. 300~ 900r.pm) with _1, P _3: or rotational speed NE is a predetermined value E ₀ (e.g. 300R.Pm) or more engine autonomous speed range, P ₄ : The rotational speed NE is a predetermined value E ₂ (for example, 4000 rpm) or more, P ₅ : The rotational speed NE is a predetermined value E ₃ (for example, 3000 rpm) or more, P ₆ : The rotational speed NE is a predetermined value E ₄ (For example, 2000 rpm) or more, or P ₇ : The opening CV of the throttle valve is a predetermined value A ₂ (for example, A ₂ = 6)
Or more), P ₈ : The rotational speed NE is a predetermined value E ₅ (eg 2000 rpm) or more, P ₉ : The throttle valve opening CV is a predetermined value A ₃ (eg A ₃ = 40)
)) Or more, and based on the results of these determinations, the operating state of the engine is in each operating region (POS0 to POS) shown in FIG.
It is determined which one of 5).

POS0: P₁ Or P₁-P₂Through P
₃Then, the engine speed NE is the predetermined value E₀When is less than
The vehicle is stopped or the engine is operating independently
If it is not in the area, P_TenWith flag F_POSTo [0]
And then P₁₁Go to. POS1: P₁ And the throttle valve opening CV is a predetermined value A₁Less than
And P₂And the engine speed is E₀And E₁Is between
When it is idling, it is determined that P ₁₂And hula
Gu F_POSIs set to [1] and P₁₃Go to.

[0022] POS2: P ₁ ~P _6, further through the P _8, when the opening degree CV of the throttle valve at P ₉ is less than the predetermined value A _3, for example, to determine that there is a low speed low load conditions, P _{At 14} , the flag F _POS is set to [3] and the process goes to P ₁₃ . POS3: When P ₁ to P ₆ through P ₇ by the throttle valve opening CV is less than a predetermined value A _2, or the rotational speed NE at P ₈ are times when less than a predetermined value E _5, or of the throttle valve at P ₉ When the opening CV is equal to or larger than the predetermined value A ₃ , it is determined that the vehicle is in the low-bundle high-load state or the starting operation state, and the flag F _{POS is set} at P _15.
Set to [5] and proceed to P ₁₃ .

[0023] POS4: When P ₁ to P ₄ engine speed in P ₅ through NE is a predetermined value or more E _3, or, when the opening degree CV of the throttle valve at P ₇ is the predetermined value A ₂ or more, for example, the determination is made that there is generally traveling state, the flag F _POS at P ₁₆
Set to [7] and proceed to P ₁₃ . POS5: P ₁ ~P ₃ engine speed at P ₄ via the NE
Is greater than or equal to the predetermined value E ₂ , it is determined, for example, that the vehicle is in a high speed state, and the flag F _POS is set to [9] at P ₁₇ and P ₁₃
Go to.

Next, in P ₁₃ , it is judged whether or not the least significant bit of the flag F _TH is "0". If "0", the process goes to P ₁₉ .
Not "0" to P _18, advance, respectively. Here, the flag F _TH corresponds to the actual position voltage V _fth output according to the actual rotational position of the cam control shaft 51 (corresponding to the state quantity related to the actual lift characteristic of the intake valve 42) CP. Then, each set value (0 to 9) is set. That is, as shown in FIG. 9, the rotation angle of the cam control shaft 51 corresponding respectively to the predetermined cam surface _{(50e~50a) (θ 1 ~θ 5} ) ( hereinafter, target position) target position voltage V against Center value V of _{fpos
fpos1 to Vfpos5} are set respectively. Then, according to the actual position voltage portion V _fth corresponding to the target position voltage region in which a predetermined dead zone (± ΔV in FIG. 9) is added to these center values V _{fpos1 to} V _fpos5 , the flag F _TH has an odd value [1. ], [3], [5], [7] or [9], and even values [0], [2] depending on the actual position voltage V _fth outside the target position voltage region (intermediate position). , [4],
It is set to [6] or [8], respectively. Therefore, when the least significant bit of the flag _FTH is "0", the flag _FTH is set to an even value (intermediate position).

At P ₁₈ , F _POS -F _TH is calculated. If the calculation result is 0, the process proceeds to P ₂₀ , and if it is positive, at P ₂₁ , the actuator 56 rotates the cam control shaft 51 to the right by a predetermined angle θ. When it is negative, the cam control shaft 51 is rotated leftward at P ₂₂ by a predetermined angle θ, and the process proceeds to P ₂₃ . P
If the actuator 56 at ₂₃ is not in operation, determine whether the difference between the flag F _TH and the flag F _POS at P ₂₄ is 0 (i.e., whether the actual position and the target position is coincident) To do. When it is 0, the count value COUNT and the flag F _ALM, which will be described later, are both cleared at P ₂₀ , the alarm 72 is deactivated, the operation of the actuator 56 is stopped at P ₁₁ , and the routine returns. If not P ₂₄ , go to P ₂₅ ,
Least significant bit of the flag F _TH at P _25, it is determined whether or not "0", "0" if not return it,
"0", the process proceeds to P ₂₆ counter (COUNT) +
1, after which the process proceeds to P _27, the count in the P ₂₇ value COUNT
And a predetermined number of times X (for example, θ / Δθ, where Δ
θ indicates the rotation angle by the correction operation), and COU
When NT ≧ X, the process proceeds to P ₂₈ , and when COUNT <X, the process proceeds to P ₁₉ . In P ₁₉ , it is determined whether the value of the flag F _{POS −the} flag F _TH is 0, and whether it is positive or negative. When it is positive, it goes to P ₂₉ , and when it is negative, it goes to P ₃₀ , 0
If so, proceed to P ₂₀ , respectively. At P ₃₀ , the actuator 56 rotates the cam control shaft 51 leftward by a preset correction angle Δθ, and at P ₂₉ it rotates rightward by a preset correction angle Δθ, and proceeds to P ₃₁ . At P ₃₁ , it is determined whether or not the stepping motor 56 is in operation. If not, at P ₃₂ , the flag F _{TH is set.}
It is determined whether or not the least significant bit of is at "0".

P₃₂With flag F_THLeast significant bit is "0"
, Then P_{twenty five}To P when not "0"₃₃Go to
Mu. P₃₃Then F_POS-F_THAnd the result is
When it is 0, P₂₀Go to and return if not 0
It Then P₂₇And the count value COUNT is a predetermined number of times X or less.
If it is above, it is judged that some kind of failure has occurred in the device
And then P₂₈With flag F_ALMIs set to "1" and P ₃₄What
move on. P₃₄Now, activate alarm 72 to alert the driver.
To do.

Next, the flow chart of the control program for controlling the ignition timing will be described with reference to FIG. At P ₄₁ , it is determined whether or not the flag F _ALM is “1”, and it is “1”.
If (in the alarm working) to P _42, proceed to "1" unless the P _43. The P ₄₃ in the ignition timing determined from the predetermined ignition timing map NAND between pulse width of the engine rotational speed NE and the fuel injection valve 73, the actual ignition output from the reference signal and the ignition timing at P ₄₄ to the distributor 74 The timing ADV is calculated and the ignition signal ST is output to the ignition coil 75.

On the other hand, the set value of the flag F _TH at P ₄₂ [1], [3], [5], to determine the [7] or [9], for example, when the flag F _TH is [1] , P ₄₅ , predetermined ignition timings respectively set according to the cam surfaces 50a to 50e in use are obtained from the map ADV1.
In P ₄₆ from the ignition timing ADV1 the reference signal actually calculates the ignition timing ADV which outputs the distributor 74 outputs the ignition signal ST to the ignition coil 75. When the set value of the flag F _TH is [3], [5], [7] or [9], the cam surface 50 in use respectively.
Ignition timing ADV3, ADV determined according to a to 50e
5, the ignition signal ST is output in accordance with ADV7 or ADV9.

Here, the operating condition of the engine is P in FIG.
A case where the cam surface 50c of the lift control cam 50 is used in the operating region indicated by OS3 will be specifically described.
First, the flag F _POS is set to [5] at P ₁₅ via P _{1 to} P ₇ , or P ₈ , or P ₉ , and the flag F _TH is output according to the rotational position CP of the cam control shaft 51. If the target position voltage V _fth is in the range of V _fpos1 , for example, it is set to [1]. At P ₁₃ , the least significant bit of F _TH becomes ≠ 0, and when F _POS -F _TH is calculated at P ₁₈ , 5
Since the -1 = 4, to rotate the stepping motor 56 in the right direction at P _21. Here, if F _POS −F _TH = 0 at P ₂₄ , the target position and the cam surface 20c match, so P ₁₁
Stops driving the stepping motor 56. F at P _{24
When POS-} F _TH ≠ 0, it is determined at P ₂₅ whether or not the least significant bit of the flag F _TH is "0". When it is "0", the actual cam surface is at the intermediate position. So X times
Is counted (+1). When it is not "0", the cam surface is at a stable position (however, whether or not it is at the target), the stepping motor 56 is further rotated by a predetermined correction angle Δθ, and at F ₃₃ , F _POS − When F _TH = 0, the excitation of the stepping motor 56 is stopped. In this way, the target cam surface 30c according to the operating area POS3
Is selected. Therefore, the lift characteristic is the curve C in FIG.
By showing the lift amount and opening / closing timing as shown in, it is possible to secure optimum filling efficiency according to operating conditions.
A stable combustion state can be obtained.

Here, at P ₂₇ , the number of correction operations is X a predetermined number of times.
If (X = θ / Δθ) or more, for example, it is determined that some failure has occurred in the actuator (stepping motor) 56, and the alarm 72 is activated to warn the driver. At the same time, the flag F _ALM is set to "1" at P ₂₈ , the _program proceeds from P ₄₁ to P ₄₂ , and the flag F _TH is judged at P ₄₂ . Here, if it is determined that the flag F _TH is [1] and the cam control shaft 51 does not rotate with the flag F _TH = 1, then P
_{At 45} , the actual ignition timing ADV is preset according to the actual cam surface 50a and is set from the ignition timing map ADV1, and the ignition signal ST is output to the ignition coil 75 of the distributor 74. Thus, when a failure occurs, for example, the actually used cam surface 50a is discriminated from the actual position of the cam control shaft 51, and the ignition timing ADV is determined according to this cam surface 50a, so knocking does not occur. Can be prevented.

As described above, in the present embodiment, since the ignition timing can be set according to the actual lift characteristic (actual lift characteristic) instead of the target lift characteristic, a phenomenon peculiar to the valve lift variable mechanism, that is, Even if the valve lift can be switched depending on whether the valve lift is open or closed, or even if the switching speed is significantly different, the actual valve lift characteristic and the ignition timing can be matched. Can be prevented and the exhaust temperature can be prevented from rising.
It should be noted that the fuel supply amount (width of the fuel injection pulse) may be controlled instead of the ignition timing, and by doing so, generation of exhaust gas can be prevented.

Alternatively, in addition to the normal control map, a control map for failure is prepared, and when a failure occurs in the variable valve lift mechanism, switching from normal operation to failure is performed and based on the actual valve lift characteristic. Ignition timing control or fuel supply amount control may be performed. It should be noted that, although description is omitted for the other operating regions POS1, POS2, POS4, or POS5 of the engine, predetermined cam surfaces 50a, 50b, 50d, 50e are respectively selected through a predetermined process. Therefore, the lift characteristics as shown by the curves a, b, d and e in FIG. 10 are obtained. As a result, the optimum filling efficiency can be secured according to the operating conditions of the engine.

When a failure occurs, each flag F _TH [3], [5], [7] indicating the intermediate position is set.
Alternatively, each predetermined ignition timing (ADV3, ADV5, ADV7 or A corresponding to the actual cam surface according to [9] is used.
Since the actual ignition timing ADV is determined from DV9) and the ignition signal ST is output, knocking can be prevented in advance. In addition, the fuel injection valve 73 depending on the cam surfaces 50a to 50e.
The pulse width of can be set to be optimum.

[0034]

As described above, according to the present invention, for example, the variation in the switching responsiveness among products caused by the variation in the clearance of the rotary sliding portion in the lift characteristic changing means is affected. According to the valve lift characteristics that are actually switched, without being affected by the variation in the switching response of one product that occurs with changes in engine temperature or changes in rotational speed, etc. The engine control can be performed accurately, and the combustion state of the engine can be maintained in good condition.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a vertical cross-sectional view of a lift variable mechanism according to an embodiment.

FIG. 3 is a plan view of an essential part of one embodiment.

FIG. 4 is an exploded perspective view showing a mounting portion of a lift control cam of one embodiment.

FIG. 5 is a diagram showing a configuration of a control circuit according to an embodiment.

FIG. 6 is a timing chart showing a control program for controlling the valve lift timing according to the embodiment.

FIG. 7 is a flowchart showing a control program for controlling ignition timing according to an embodiment.

FIG. 8 is an explanatory diagram illustrating each operating region based on the relationship between the number of engines and the throttle valve opening according to the embodiment.

FIG. 9 is a graph showing a relationship between a rotation angle of a cam control shaft, a target position voltage, and a flag F _{TH according} to an embodiment.

FIG. 10 is a graph showing a valve lift characteristic of the example.

FIG. 11 is an overall configuration diagram of a conventional example.

FIG. 12 is a vertical cross-sectional view of a conventional valve timing control device.

13 is a view in the Y direction of FIG.

FIG. 14 is a switching timing diagram of valve timing in a conventional example.

FIG. 15 is an operation characteristic diagram illustrating the operation of the conventional example.

[Explanation of symbols]

41: drive cam (opening / closing drive means), 42: intake / exhaust valve, 43: rocker arm (opening / closing drive means), 45: lever (opening / closing drive means), 50: lift control cam (lift characteristic changing means), 51: cam Control axis (lift characteristic changing means), 56: Actuator (lift characteristic changing means), 57: Control circuit (target lift characteristic setting means, first control means, second control means, abnormality determination means), 66: Crank Angle sensor (operating state detecting means), 67: throttle valve opening sensor (operating state detecting means), 69: potentiometer (actual lift characteristic detecting means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuro Matsumoto 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (5)

[Claims] 1. An operating state detecting means for detecting an operating state of an engine, an intake / exhaust valve for opening / closing an intake port or an exhaust port, and an opening / closing drive means for opening / closing the intake / exhaust valve in synchronization with engine rotation. And a lift characteristic changing means for changing the lift characteristic of the intake / exhaust valve by switching the operation mode of the opening / closing drive means, and a target lift characteristic for setting the target lift characteristic of the intake / exhaust valve according to the operating state of the engine. Setting means, actual lift characteristic detecting means for detecting a state quantity related to actual lift characteristics of the intake / exhaust valve, and controlling the lift characteristic changing means so that the target lift characteristic and the actual lift characteristic match. A first control means; and a second control means for controlling a physical quantity involved in combustion of the engine based on the output of the operating state detection means and the output of the actual lift characteristic detection means. An intake / exhaust valve lift control device for an internal combustion engine, characterized by: 2. The second control means has a plurality of control maps set in advance corresponding to respective operating regions of the engine, and one of the control maps based on the output of the actual lift characteristic detection means. 2. The intake / exhaust valve lift control of an internal combustion engine according to claim 1, wherein the physical quantity involved in combustion of the engine is controlled based on the selection map and the output of the operating state detecting means. apparatus. 3. An abnormality determining means for determining an abnormality when the actual lift characteristic and the target lift characteristic do not match each other even after a lapse of a predetermined period, and the second control means normally operates. While controlling the physical quantity involved in combustion of the engine based on the output of the detection means, at the time of abnormality determination, the physical quantity involved in combustion of the engine based on the output of the actual lift characteristic detection means and the output of the operating state detection means. The intake / exhaust valve lift control device for an internal combustion engine according to claim 1 or 2, which is controlled. 4. The intake / exhaust valve lift control device for an internal combustion engine according to claim 1, 2 or 3, wherein the physical quantity involved in combustion of the engine is an ignition timing of the engine. 5. The intake / exhaust valve lift control apparatus for an internal combustion engine according to claim 1, 2 or 3, wherein the physical quantity involved in combustion of the engine is a fuel supply quantity of the engine.