JPS61244871A - Intake and exhaust valve life control device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of knocking, by a method wherein a cam control shaft is rotated from an actual position toward a desired position set based on the operating condition of an engine, and when a failure in operation occurs, an ignition timing is controlled according to an actual cam surface depending on an actual position. CONSTITUTION:Through detection of the actual position of a cam control shaft b means of a position detecting means (e), the cam control shaft is rotated in a given angle arc so that the actual position coincides with a desired position which is an optimum valve timing responding to the operating condition of an engine detected by an operating condition detecting means (d). In which case, when a failure in operation occurs to, for example, a stepping motor, the failure in operation is discriminated by a control means (f), and an actual ignition timing is decided from an ignition timing map determined according to an actual cam surface depending upon the actual position of a cam control shaft to output an ignition signal to a distributor (a). This, even when a failure in operation occurs, enables prevention of the occurrence of knocking.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an intake/exhaust valve lift control device for an internal combustion engine that variably controls the lift characteristics of intake/exhaust valves according to engine operating conditions.

(Prior art) As a conventional intake/exhaust valve lift control device, for example,
0 to 14 are known (see Japanese Utility Model Application Publication No. 141170/1983).

To briefly explain this device, in FIG. 10, 1 is a cylinder block, 2 is a cylinder head, 3 is a piston,
4 is a crankshaft. A timing boot 175 is fixed to one end of the crankshaft 4, and this pulley 5 is connected to a timing pulley 8 provided at one end of the camshaft 7 via a timing belt 6. 9 is a distributor having a main body 9A and a distributor shaft 9B, and the distributor shaft 9B meshes with the camshaft 7 by a gear (not shown). A breaker plate is disposed within the main body 9A and is connected to the advance angle control negative pressure actuator 10. The negative pressure actuator 10 is of 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 vibrator 11 to perform negative pressure advance control.

A valve timing control device is provided between the timing pulley 8 on the camshaft 7 and the camshaft 7 to control the rotational phase of the camshaft 7 with respect to the crankshaft 4 (FIGS. 11 and 12). In Figures 11 and 12, 2
1 is a stepping motor, and when this motor 21 is driven, the rotational motion of its output shaft n is converted into a linear motion of the driving lever by the action of the screw part, and as a result, the bearing support U is driven by the rotation of the motor 21. It moves left and right in Figure 11 depending on the direction. This left and right movement of the bearing support U is transmitted to the bearing and the nail through the shaft portion, and the bearing path and the nail move in the direction of arrow A in FIG. 12 while rolling within the slits 4 and 29. Then slit 28.29
Since they intersect, relative rotation occurs between the outer sleeve 30 and the inner sleeve 31, so that the relative angular position between the crankshaft 4 and the camshaft 7 changes.

Here, when controlling the rotational phase of the camshaft 70 with respect to the crankshaft 4, the control circuit 32 controls the valve timing of the motor 21 according to the operating range of the engine (valve timing switching diaphragm) as shown in FIG. For switching, a forward/reverse rotation signal is output (Fig. 14 (a)). As a result, the valve timing switches between "0'" and "1" shown in Figure 13, and the three-way switching valve blade operates in synchronization with this switching (Figures 10 and 14 (b)). . That is, in response to the forward rotation signal, the three-way switching valve blades introduce negative pressure into the negative pressure chamber 10B of the actuator 10, so the advance angle control shaft 34 of the actuator 10 is set to the 10th position so that the breaker plate 9C of the distributor 9 rotates in one direction. Move it to the left in the figure. At this time, the angular position of the breaker plate 9C is represented by θ. Also, the position of the breaker plate 9C is expressed as θ2 by the reversal signal (Fig. 14 (c))
. The rotational displacement Δθ of the breaker plate 1-9C in synchronization with such valve timing switching corresponds to the relative rotation of the camshaft 7 with respect to the crankshaft 4, and no deviation in ignition timing occurs due to valve timing switching (Fig. 14). (d))
.

In addition, in accordance with the time lag 11 and β2 (Fig. 14 (b)) of the aperture blades and switching of the aperture blades shown in Fig. 10, the introduction speed of negative pressure or atmospheric air is adjusted to m□, m2 shown in Fig. 14 (c). This eliminates lag in ignition timing at each point during switching.

(Problem to be solved by this invention) However,
In such conventional intake/exhaust valve lift control devices, valve timing is switched by driving a motor to change the relative phase between the crankshaft and the camshaft.
The ignition timing for the distributor was controlled according to this valve timing switching, so if the motor that switches the valve timing fails, the actual ignition timing will match the required ignition timing set according to the operating conditions. There were cases where it did not.

As a result, knocking occurs, and in the worst case, the engine may be damaged.

(Means for Solving the Problems) The present invention has been made to solve these problems, and the overall configuration diagram thereof is shown in FIG. 1.

That is, the present invention has a camshaft connected to the distributor a, transmits the driving force of the engine to the intake/exhaust valves via the camshaft, and has a lift control cam stage having a plurality of cam surfaces. A variable intake/exhaust valve lift mechanism that changes the lift characteristics of the intake/exhaust valves in response to changes in the lift control shaft rotates the cam control shaft, which rotatably supports the lift control cam, to the target position so as to form the target cam surface. a driving means C for dynamically changing; an operating state detecting means d for detecting the operating state of the engine; a position detecting means e for detecting the actual position of the cam control shaft;
The driving means is driven to rotate the cam control shaft from the actual position toward the target position that is set based on the operating state of the engine, and when a failure occurs, the failure is determined and the actual position is determined. and control means f for controlling the ignition timing for the distributor in accordance with the actual cam surface corresponding to the cam surface.

(Function) In this invention having such a configuration, the actual position of the cam control shaft is detected, and the actual position is matched with the target position that provides the optimum valve timing according to the operating condition of the engine. , the cam control shaft is rotated by a predetermined angle in a predetermined direction. Here, when a failure occurs in the device, for example, the stamping motor, this is determined by the control means,
The actual ignition timing is determined from a predetermined ignition timing map according to the actual cam surface corresponding to the actual position of the cam control shaft, and an ignition signal is output to the distributor. Therefore, even if a failure occurs, knocking can be prevented from occurring.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 2 to FIG. 9 are diagrams showing an embodiment of the present invention.

First, to explain the configuration, as shown in FIG.
A rocker arm 43 is provided with both ends in contact with the stem end of the intake valve 42, and a shaft 43b protrudes from both side walls of the rocker arm with a curved back surface 43a of the rocker arm in fulcrum contact. A lever 45 is provided for holding the inside of the concave groove 45a via a holding member. Note that the camshaft 41A is connected to a distributor shaft of a distributor 74, which will be described later.

A spring 46 with a small spring constant is interposed between a spring seat 45b formed on the lever 45 and the holding member 44, and biases the rocker arm 43 downward in FIG.

Also, a bracket 48 interposed in the cylinder head 47
The spherical lower end surface of the hydraulic pivot 49 fitted and held in the lever 45 is fitted into the recessed part 45c formed in the underlined top wall of the stem end of the intake valve of the lever 45. A lift control cam (equipment), which is rotatably attached to the bracket 48 as will be described later, comes into contact with the top wall of the end of the lever 45 on the drive cam 41 side, thereby supporting the lever 6 in a freely swinging manner. The swing position of 45 is regulated.

The hydraulic pivot 49 has an outer cylinder 49 whose lower end surface fits into the concave portion 45C of the lever 6, and whose peripheral surface is slidably inserted into the mounting hole 48a formed in the bracket 48.
a and extranuclear? ? 149a, and a check valve 49d in a hydraulic chamber 49c formed between the two.

Then, from the hydraulic pressure supply passage 48 b formed inside the bracket 48 to the inside of the inner cylinder 49 b and the check valve 49
The valve clearance is maintained at zero by supplying hydraulic pressure to the hydraulic chamber 49C via the valve d.

The lift control cam 50 has five substantially flat cam surfaces 50 on its outer circumferential surface so as to change the lift amount of the intake valve 42 in stages.
a to 50e, and has a hole 50g in the center through which a cam control shaft 51, which will be described later, is inserted.

Further, the outer circumferential surface of the cylindrical portion 50h formed to protrude from both sides of the lift control cam 50 is connected to the lower arcuate groove 48 formed in the bracket 48, as shown in FIGS. 3 and 4.
c and an upper arcuate groove a formed in a pair of cap sleeves fastened with bolts 52 on the bracket mallet.

Then, one cam control shaft 51 is passed through a hole 50g formed through the center of the lift control cams 50 provided in several cylinders, and the cam control shaft 51 is fitted into both sides of each lift control cam 50. One end of the inserted coil spring tube is locked to a set screw 51a screwed into the outer wall of the cam control shaft 51, and the other end of the coil spring 54 is fitted into a hole formed in the side wall of the cylindrical portion 50h of the lift control cam. Insert and lock.

One end of the cam control shaft 51 is connected to a drive shaft 56 of an actuator 56 (for example, a stevening motor) via a joint 5.
connected to a. Actuator % is control circuit 57
The cam control shaft 51 is rotated by being driven by a drive signal SK from the cam control shaft 51.

In addition, 58 is a valve spring, and 69 is a potentiometer described later.

Next, the configuration of the control circuit 57 will be explained based on FIG. The control circuit 57 has a function as a control means, and mainly controls the central processing unit CPU60 and the read-only memory R.
It is composed of an OM 61, a random access memory IJRAM 62, and an I10 boat (input/output signal processing device) 63. The CPU 60 is regularly operated by the clock, takes in necessary external data from the I10 port 8 according to the program written in the ROM 61, and exchanges data with the RAM 62 via a pass line conversation. It performs arithmetic processing while outputting data to the I10 port 63 as necessary. RAM62
performs temporary storage of external data.

Here, the engine rotation speed NE is detected by, for example, a crank angle sensor mark and is used as a rotation speed signal, and the crank angle vertical dead center position KP is a vertical dead center position reference signal (hereinafter referred to as
Each I10 port is simply output as a reference signal). Further, the opening degree CV of the throttle valve is detected by the throttle valve opening degree sensor a, and after being converted into a digital signal by an A/D converter mark, the rotational position C of the cam control shaft 51 is output as a throttle valve opening degree signal.
P is detected by a potentiometer 69 (position detecting means), converted into a digital signal by an A/D converter 70, and then outputted to the I10 port 63 as an actual position signal Vf th. Furthermore, the actuation/inactivation signal SA for detecting the actuation/inactivation of the actuator is sent to the drive circuit 7.
1 to the I10 port 63. The crank angle sensor 66 and the throttle valve opening sensor nail collectively constitute engine operating state detection means,
The control circuit 57 calculates control values (the amount of rotation of the cam control shaft 51, the rotation direction), and calculate the cam surface 5
A drive signal SK is output to the actuator 56 via the drive circuit 71 so that 0a-50e becomes a predetermined target cam surface. Further, when determining that a failure has occurred, the control circuit 57 outputs a warning signal SB to the alarm 72 and activates the alarm 72.

Further, an injection signal SF of a predetermined pulse width (energization time) controlled by the reference signal is applied to the fuel injection valve 73 and an ignition coil 7 connected to the distributor 74
5, an ignition signal ST is outputted in accordance with a predetermined ignition timing which is also controlled by the reference signal.

Next, the action will be explained.

Figure 6 (A) shows the cam surface 5 written in the ROM61.
FIG. 6(B) is a flowchart showing a control program for selecting and controlling 0a to 50e, and FIG. 6(B) is a control program for controlling ignition timing, and PL-P46 in the figure indicates each step of the flowchart. These programs are executed, for example, once for each revolution of the engine.

First, in P1 to P9, as shown in FIG. 7, each operating range (PO3o to pos) is set from the relationship between the opening Cv of the throttle valve and the engine speed NE.

).

Pl: The opening degree CV of the throttle valve is a predetermined value A, (for example, A1
P2: Is the rotation speed NB in the idle rotation speed range between the predetermined value EO and the predetermined value E (for example, 300 to 900 r, p, m,)?P , 8 rotation speed NE is a predetermined value Eo (for example, 30Q r,
P4: Is the engine rotation speed NE within a predetermined value E, (e.g. 4000 r, p
, m, ) or more or P: If the rotational speed NE is a predetermined value E, (for example 3000r, p
, m, ) or more P9: The rotational speed NE is a predetermined value E4 (e.g. 200O
r, p, m, ) or more or P: The opening CV of the throttle valve is a predetermined value A2 (for example, A2
-6°) or more P8: The rotational speed NE is equal to or greater than the predetermined value E (for example, 2000r
, p, n+, ) or more P9: The throttle valve opening CV is a predetermined value A, (for example, A3
= 40°) or more, and from these determination results, it is determined in which of the operating ranges (POSO to P055) the engine is in as shown in FIG.

PO30: P+ or P! - When the engine speed NE is less than the predetermined value 80 at P3 after passing through P2, it is determined that the vehicle is in a stopped state or that the engine is not in the self-sustaining operation range, and the process proceeds to P3.

Set the flag Fpos to O with and proceed to pH.

Po5t: When the opening degree CV of the throttle valve is less than the predetermined value A8 at P, and the engine speed is between EO and El at P2, it is determined that the engine is in an idling state and the flag Fpos is set to 1 at P+2. Set it and proceed to Pll.

PO32: When the throttle valve opening CV is less than the predetermined value A3 after passing through P,=Po, and then P, it is determined that the throttle valve is in a low speed, low load state, for example, and a flag is set at P14. Set pos to 3 and proceed to Pr1.

PO33: Throttle valve opening CV at P7 via P, ~Pg
is less than the predetermined value A2, ° or when the rotation speed NE is equal to or greater than the predetermined value E3 at P8, or when the opening degree CV of the throttle valve is equal to or greater than the predetermined value A1 at P9, for example, a low speed, high load state or a start operation is performed. It is determined that the condition is present, the flag Fpos is set to 5 using PIs, and the process proceeds to pH.

PO34: P, through P4, engine rotation speed N
When E is greater than or equal to the predetermined value 81, or when the throttle valve opening CV is greater than or equal to the predetermined value A2 at P7, it is determined that the vehicle is in a normal driving state, and the flag Fpos is set to 7 at P+6. Proceed to PB.

PO55: Engine speed NE at P4 after passing from Pt to P3
When Pr? is greater than or equal to a predetermined value of 82, it is determined that the vehicle is in a high speed state, and Pr? Set the flag p'pos to 9 and proceed to pi.

Next, the Pll determines whether the least significant bit of the flag Fth is in O, and if it is 0, it is sent to PI9, if it is not 0, it is sent to P,
%, respectively. Here, the flag Fth is set to each set value (0 to 9) corresponding to the actual position voltage Vfth output according to the actual rotational position CP of the cam control shaft 51.

That is, as shown in FIG.
Target position voltage Vfpos (7) center value vfpO31 to vfpos,
are set respectively. And these center values Vfp
A predetermined dead zone (±ΔV in Figure 8) is set between os engineering and Vfpos5.
) is set to an odd value (1, 3, 5) according to the actual position voltage Vfth corresponding to the target position voltage region with
, 7, 9), and the even value (
0, 2, 4, 6, 8), respectively.

Therefore, when the least significant bit of flag Fth is 0, flag Fth is set to an even value (intermediate position).

PI calculates Fpos-Fth, and if the calculation result is O, then P. If it is positive, the actuator 56 rotates the cam control shaft 51 by a predetermined angle θ in the right direction with pJL+, and if it is negative, the cam control shaft 51 is rotated in the left direction by a predetermined angle θ with PJL+. and proceed to P2S. At Pz3, if the actuator 56 is not in operation, the difference between the flag Fth and the flag Fpos is O at P Yuna.
(that is, whether the target position and the actual position match). When it is 0, both the count value C0UNT and the flag Fa1m, which will be described later, are cleared using Pw, the alarm 72 is deactivated, and the operation of the actuator 56 is stopped based on the pH, and the process returns.

If P2't is not O, proceed to P, 5, determine whether the lowest bit of flag Fth is O at P Judah,
If it is not 0, return, and if it is 0, proceed to the second magazine. In P engineering and others, add +1 with the counter and proceed to P27.
In P Near, the count value C0UNT is compared with the number of correction operations X (for example, θ/Δ", here, Δθ indicates the rotation angle due to the correction operation), and when C0UNT≧X, PzQ ″advances′C0UNT <If X, proceed to PI3. At P+9, it is determined whether the value of flag Fpos-flag Fth is 0 and whether it is positive or negative.
If positive, go to P, (l; if negative, go to P,.
If it is 0, proceed to P respectively. In Pro, the cam control shaft 51 is rotated to the left by a preset correction angle Δθ by the actuator, and in P29, the cam control shaft 51 is rotated to the right by a preset correction angle Δθ, and the process proceeds to Pal. Pll determines whether the stepping motor % is operating or not, and if it is not operating, P32
It is determined whether the least significant bit of flag Fth is 0 or not.

When the lowest bit of the flag Fth is O in P, 2, the process goes to P disease, and when it is not O, the process goes to P33.

PI3 calculates Fpos-Fth, and if the result of the calculation is 0, proceed to P; otherwise, return.

Next, when the count value C0UNT is equal to or greater than the predetermined number of correction operations X at Pll, it is determined that some kind of failure has occurred in the device, and the flag Fa1m is set to 1 at Pλ6, and the process proceeds to P34. In P3Dou, the alarm 72 is activated to issue a warning to the driver.

Next, a flowchart of a control program for controlling ignition timing will be explained based on FIG. 6(B).

p4. , it is determined whether the flag Fa1m is 1 or not, and if it is 1 (alarm activated > P4), if it is not 1, proceed to P+3.In P4. The ignition timing is determined from the predetermined ignition timing map NAND during the pulse of the valve 73, and the distributor 7 is determined from the reference signal and this ignition timing using P@.
The actual ignition timing ADV to be outputted to the ignition coil 75 is calculated and the ignition signal ST is outputted to the ignition coil 75.

On the other hand, P+2. Then, set value of flag Fth (1, 3,
5, 7, 9), and for example, when the flag Fth is 1, the cam surfaces 50a to 50e in use at P4%'
The predetermined ignition timings, which are set according to the respective values, are obtained from the map ADV1. P44. Now, from this ignition timing ADVI and the reference signal, we can actually determine the distributor 7.
The ignition timing ADV that outputs 4 is calculated and the ignition signal ST is output to the ignition coil 75.In addition, when the set value of flag Fth is either 3.5.7.9, the cam surface in use is The ignition signals ST are outputted in accordance with the ignition timings ADV3 to ADv9 determined according to the timings 50a to 50e, respectively.

Here, when the operating conditions of the engine are in the operating range indicated by PO33 in FIG.
The case where c is used will be specifically explained.

First, flag Fpos is set to 5 at PFi via p, ~p7, or P8, or P9, and flag Fth
is set to 1 if the target position voltage Vfth output according to the rotational position CP of the cam control shaft 51 is in the range of, for example, Vpos. Bij≠0 in PI3, and Fp in PI3.

When calculating 5-Fth, 5-1=4, so Pm
Rotate the stepping motor 56 to the right with l. Here, if Fpos-Fth=0 at Pll, the target position and the cam surface 20c match, so the drive of the stepping motor 56 is cut off at Pll. Fpos with 2 riders
When Fth≠0, use pg to determine whether the lowest bit of flag Fth is 0 or not. If it is 0, the actual cam surface is at the intermediate position, so count the number of correction operations X. . Also, if it is not 0, the cam surface is in a stable position (however, whether it is at the target position or not), the stepping motor section is further rotated by a predetermined correction angle Δθ, and the Pll is set to Fpos-Fth-0. If so, the excitation to the stepping motor section is stopped. In this way, the target cam surface 30c corresponding to the operating range POS3 is selected. Therefore, the lift characteristic shows the lift amount and opening/closing timing as shown by curve C in FIG. 9, and it is possible to secure the optimum charging efficiency according to the operating conditions and obtain a stable combustion state.

Here, in Pz7, the number of correction operations is set to a predetermined number of times X (X=θ/
Δθ) or more, for example, the actuator (
It is determined that some kind of failure has occurred in the stepping motor (stepping motor) 56, and an alarm 72 is activated to warn the driver.

At the same time, flag Fa1m is set to 1 at Pλ8, and P
Proceeding from H1 to P42, the flag Fth is determined in P42. Here, if it is determined that the flag Fth is 1 and the cam control shaft 51 does not rotate with the flag Fth=1, the ignition timing map ADV1 is set in advance according to the actual cam surface 50a using the P bamboo. The actual ignition timing ADV is set and the ignition signal ST is output to the ignition coil 75 of the distributor 74. In this way, when a failure occurs, the cam surface 50a that is actually used is determined from the actual position of the cam control shaft 51, and the ignition timing ADV is determined according to this cam surface 50a, so that knocking can be prevented. This can prevent damage to the engine from occurring.

In addition, other operating ranges of the engine PO31, PO32, P
O34 and PO35 are also omitted from description, but are formed into predetermined cam surfaces 50a, 5Qb, 50d', 5 through a predetermined process.
0 e are selected respectively. Therefore, a lift characteristic as shown by the curve ax bz dz 15 in FIG. 9 is obtained. As a result, optimal charging efficiency can be ensured depending on the operating conditions of the engine.

In addition, if a failure occurs, each predetermined ignition timing (ADV3, ADV3, A
DV5, ADV? , ADV9) to the actual ignition timing A
Since the DV is determined and the ignition signal ST is output, the occurrence of non-king can be prevented. In addition, the cam surface 50 a
~50 The pulse period of the fuel injection valve 73 can also be set to be optimal according to e.

(Effects) As explained above, according to the present invention, it is possible to accurately rotate the cam control shaft to the target position for obtaining the optimal valve timing, so it is possible to achieve optimal filling according to the engine operating conditions. You can gain efficiency. In addition, the device
For example, even if some kind of failure occurs in the motor, the failure can be easily identified and the ignition timing can be determined according to the actual cam surface, making it possible to prevent non-king and, in turn, engine damage. This can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an intake/exhaust valve lift control device for an internal combustion engine according to the present invention, and FIGS. 2 to 9 are diagrams showing an embodiment of the present invention. A vertical cross-sectional view of the variable lift mechanism, FIG. 3 is a plan view of the main part thereof, FIG. 4 is an exploded perspective view showing the mounting part of the lift control cam, FIG. 5 is a diagram showing the configuration of the control circuit, and FIG. A) is a flowchart showing a control program that controls valve lift timing, FIG. 6(B) is a flowchart showing a control program that controls ignition timing, and FIG. 7 shows each operation based on the relationship between engine speed and throttle valve opening. An explanatory diagram explaining the area, FIG. 8 shows the rotation angle of the cam control shaft, the target position voltage, and the flag Fth.
FIG. 9 is a graph showing the valve lift characteristics, FIGS. 10 to 14 are diagrams showing conventional intake/exhaust valve lift control devices, and FIG. 10 is an overall configuration diagram. Figure 11 is a vertical cross-sectional view of the pulp timing control device;
The figures are a view taken in the direction of arrow X in FIG. 11, FIG. 13 is a valve timing switching diagram, and FIG. 14 is an operation characteristic diagram illustrating its operation.

Claims (1)

[Claims] It has a camshaft connected to a distributor that controls ignition timing, transmits engine driving force to intake and exhaust valves via the camshaft, and has a stepwise change in lift control cam that has multiple cam surfaces. A variable intake/exhaust valve lift mechanism that changes the lift characteristics of the intake/exhaust valves according to a driving means, an operating state detecting means for detecting the operating state of the engine, a position detecting means for detecting the actual position of the cam control shaft, and a position detecting means for detecting the actual position of the cam control shaft toward the target position set based on the operating state of the engine. control for driving the drive means to rotate the cam control shaft from the cam control shaft, and determining the failure when a failure occurs and controlling the ignition timing for the distributor in accordance with the actual cam surface corresponding to the actual position. An intake/exhaust valve lift control device for an internal combustion engine, comprising: means.