JPH0810674Y2 - Valve timing control device for internal combustion engine - Google Patents

Description

The present invention relates to a valve timing control device for an internal combustion engine, and more specifically to an internal combustion engine that detects an abnormality of a variable valve timing mechanism from the vibration level of the engine. Valve timing control device.

(Prior Art) Recently, in order to meet the high output demand of the engine, a technique has been proposed in which the valve timing of the intake and exhaust valves is made variable according to the operating state of the engine. In that technology, for example, in an engine having four valves per cylinder, three cams are attached in parallel on a cam shaft, and the cams located at both ends determine the valve timing at low engine speed, and The cam located at determines the valve timing at high speed. That is, the three rocker arms are arranged in sliding contact with the three cams, and the rocker arms at both ends are connected to the intake and exhaust valves, respectively, and at the time of low speed operation, the central rocker arm is made to idle and at the timing determined by the cams at both ends. Open and close the intake and exhaust valves. Thus, the three rocker arms can be connected by pins, and during high speed operation, the pins are moved by hydraulic pressure to connect the three rocker arms and suck at the high speed valve timing defined by the cam at the center position. The exhaust valve is opened and closed so that the valve timing (and lift amount) is changed according to the operating state. As an example of such a conventional technique, for example, a technique described in JP-A-62-121811 can be mentioned.

(Problems to be solved by the invention) Therefore, in this variable valve timing mechanism,
A hydraulic switch is provided in an oil passage through which the hydraulic oil that drives the pin is detected to detect whether the pin is normally connected or disconnected. However, if the connecting pin bites into a foreign object or the like and locks, the hydraulic pressure itself changes as instructed, so that no abnormality appears in the hydraulic switch and the pin lock cannot be detected. In such a variable valve timing control, since the operation of the engine such as the ignition timing or fuel injection is individually performed according to the timing range, for example, a change in the valve timing command signal and the output of the hydraulic switch is monitored, If the valve timing command signal and hydraulic switch output continue to be in different states for more than a predetermined time, failsafe measures are taken, such as determining that the mechanism is abnormal. It takes time and is an indirect abnormality detection, and in any case, it is not preferable to leave such a state for a long time because knocking is likely to occur.

By the way, in the internal combustion engine provided with such a variable valve timing mechanism, the seating time of the intake and exhaust valves differs by changing the valve timing. Further, the vibration level (or sound) of the intake / exhaust valve when seated varies slightly depending on the valve diameter and the like, but generally occurs in a predetermined frequency band. FIG. 15 shows a measurement of the valve seating noise of the intake valve, and as shown in the figure, it strongly occurs near 12 kHz.

The present invention was made on the basis of the above-mentioned findings.It was made by paying attention to the fact that the valve seating position changes when the valve timing is different and the valve seating noise is a substantially constant value. An object of the present invention is to provide a valve timing control device for an internal combustion engine, which detects the position where the valve seating noise is generated, and then detects the abnormality of the variable valve timing mechanism.

(Means and Actions for Solving the Problem) In order to achieve the above-mentioned object, the present invention, as shown in FIG. 1, according to the operating state of the engine, at least one of the intake and exhaust valves has a valve timing and / or a lift amount. In a valve timing control device for an internal combustion engine, which comprises a variable valve timing mechanism for selectively changing among a plurality of characteristics,
Vibration level detection means 1 for detecting the vibration level generated in the engine, operation characteristic determination means 2 for determining the operation characteristic instructed to the variable valve timing mechanism, crank angle detection means 3 for detecting the crank angle of the engine, and the crank Crank angle range setting means 4 for setting the crank angle range for fail determination of the variable valve timing mechanism according to the commanded operation characteristics by inputting the outputs of the angle detection means and the operation characteristic determination means, and the operation characteristic determination Reference level setting means 5 for inputting an output of the means and setting a reference level for fail determination of the variable valve timing mechanism according to a commanded operation characteristic, and the reference level setting means and the vibration level detecting means, And the output of the crank angle range setting means, and the output value of the vibration level detecting means in the crank angle range. The comparison with the reference level, was constructed as consisting of the fail detection means 6 for detecting an abnormality of the variable valve timing mechanism.

(Operation) By detecting whether or not the valve seating noise actually occurs in the crank angle range that should be generated according to the commanded valve timing, the variable valve timing mechanism operates at the actually commanded timing. It is possible to determine whether or not there is.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.
FIG. 2 is an overall schematic view of a knock control device for an internal combustion engine according to the present invention. To explain according to FIG.
Reference numeral 10 denotes a multi-cylinder internal combustion engine for a vehicle including four cylinders and the like. The intake pipe 12 is provided with a throttle valve 14 at an appropriate position. The flow rate of intake air introduced from an air cleaner (not shown) attached to the tip of the intake pipe is adjusted by the throttle valve 14, and a fuel injection valve is provided. (Not shown)
Is supplied to the combustion chamber 22 through the intake port 20 provided in the cylinder head 18. Combustion chamber
At 22, the air-fuel mixture is compressed by the piston 24, ignited by the spark plug 26, explodes, and drives the piston 24 downward to be discharged through the exhaust pipe 30 through the exhaust pipe 30 to the outside of the engine. .

Here, a throttle position sensor 32 for detecting the opening of the throttle valve 14 provided in the intake pipe 12 is provided at an appropriate position in the engine, and a pipe (not shown) is provided in the intake pipe 12 downstream of the throttle valve 14. Is connected and branched, and an intake pressure sensor 34 that measures the pressure of the intake air in absolute value is provided near the end of the branch path, and the temperature of the intake air is detected at an appropriate position downstream of the branch point. An intake air temperature sensor 36 is provided. The cylinder block of the internal combustion engine 10
In the vicinity of the cooling water passage 40 in the 38, a water temperature sensor 42 is provided to detect the temperature of the engine cooling water, and in the vicinity thereof, a piezoelectric type that is the vibration detecting means for detecting the vibration generated in the combustion chamber 22. The knock sensor (non-resonant type) 44 is provided. Further, a distributor 46 is provided at an appropriate position of the internal combustion engine 10, and inside thereof, a magnet that rotates in synchronization with the rotation of a crank shaft (not shown) that rotates with the vertical movement of the piston 24, and a magnet facing it. A crank angle sensor 48 made up of rotating bodies arranged in the same manner is housed, and various angle signals including a cylinder discrimination signal output once per 720 degrees of crank angle are output for each predetermined crank angle. In addition, a vehicle speed sensor 50 that detects the traveling speed is located at an appropriate position on the vehicle.
Is provided. The outputs of the sensors 32, 34, 36, 42, 44, 48, 50 such as the above-described throttle position sensor are sent to the control unit 52.

The control unit 52 will now be described with reference to FIG. 3. An analog output of the throttle position sensor 32 or the like is input to a level conversion circuit 64 in the control unit to be converted to a predetermined level and input to a microcomputer 66. To be done. The microcomputer includes an A / D conversion circuit 66a,
I / O 66b, CPU 66c, ROM 66d, RAM 66e, registers for operation and timer (register and timer are not shown)
The output from the level conversion circuit is converted into a digital value in the A / D conversion circuit 66a in accordance with a command from the CPU 66c, and then temporarily stored in the RAM 66e. Also, the crank angle sensor 48
And the like are input to the microcomputer via the I / O 66b after waveform shaping in the waveform shaping circuit 68.

Furthermore, the output of the knock sensor 44 is the control unit.
After being transmitted to 52, it is input to knock detection circuit 70. The knock detection circuit 70 includes a filter means 70a, a comparator means 70b and a D / A conversion means 70c. The filter means 70a is
It has a band characteristic of passing a frequency component near 12 kHz, receives the output of the knock sensor 44, passes only that frequency component, and sends it to the non-inverting input terminal of the comparator means 70b. The output terminal of the comparator means 70b is connected to the microcomputer 66, and its inverting input terminal is connected to the output terminal of the D / A conversion means 70c. D /
The input terminal of the A conversion means 70c is a microcomputer 66
Connected to.

In the knock detection circuit 70, a comparator means
At 70b, the sensor output is compared with the reference value set by the microcomputer 66 to calculate the noise level and determine the knocking.
Explaining with reference to the chart, from the microcomputer 66, an appropriate crank angle range which is not in a combustion state (for example,
At ATDC 120 to 140 degrees, hereinafter referred to as "noise gate"), the noise level VNOISE which is the background value of engine vibration is output to the D / A conversion means 70c as a comparison reference value. The output value is converted into an analog value by the D / A converter 70c, and is compared with the sensor output level by the comparator 70b. The microcomputer 66 changes the noise level based on the comparison result. The noise level is set to be near the peak value of the sensor output level.

Further, the microcomputer 66 controls the noise level VNOISE in an appropriate crank angle range (for example, ATDC 10 to 50 degrees, hereinafter referred to as "knock gate") in a combustion state.
A knock determination level is calculated by multiplying a predetermined coefficient G (a value appropriately set according to the driving state) on the basis of the above, and the calculated knock determination level is output to the comparator means 70b via the D / A conversion means 70c. . The comparator means 70b compares the sensor output level with the knock determination level, and sends the comparison result to the microcomputer 66. When the sensor output exceeds the knock determination level, the microcomputer 66 determines that knock has occurred. Based on the comparison result, the microcomputer 66 determines the final ignition timing, drives the igniter 62 composed of an igniter or the like via the output circuit 74, and ignites the air-fuel mixture in the combustion chamber 22 through the ignition plug 26. In addition, at an appropriate position between the noise gate and the knock gate, an angle section shown as "fail gate" in the figure is provided, and it is determined whether or not the operation of the variable valve timing mechanism is normally performed therein. A fail determination operation for performing the operation is performed, which will be described later. Since the fail gate is for monitoring the seating of the intake valve, it goes without saying that it is a cylinder different from the cylinder in the explosion process in which knock determination is performed.

Returning to FIG. 2 again, in the internal combustion engine 10, the variable valve timing mechanism 60 is connected to the intake valve 54 that opens and closes the intake port 20 and the exhaust valve 56 that opens and closes the exhaust port 28. The valve timings and lift amounts of the intake and exhaust valves 54 and 56 are variably driven according to the above. This variable valve timing mechanism will be briefly described with reference to FIG. FIG. 5 is an explanatory sectional view showing a hydraulic pressure switching device of a variable valve timing mechanism. Since the variable valve timing mechanism 60 has the same structure on both the intake valve side and the exhaust valve side, the members on the intake side are denoted by the suffix i and the members on the exhaust side are denoted by the suffix e in the drawings. Is performed in common for both, without adding a subscript.

Three rocker arms are rotatably supported on a rocker shaft 612 provided in parallel with a cam shaft (not shown) in the lower part of FIG. Of these, the first of both ends
Rocker arm 614 and second rocker arm 616 are in sliding contact with two low-speed rotation cams (not shown) fixed on the camshaft, and the third rocker arm 618 at the center is also fixed on the camshaft. A high-speed rotation cam (also not shown). The profile of the high-speed cam is set such that the cam has a greater degree of protrusion in the radial direction of the camshaft and a larger rocking amount of the rocker arm than the low-speed cam. Thus, the three rocker arms 614, 616, 618 are bored transversely at their free ends to form a hole 632 and a hole 634, 636 continuously, in which the first connecting pin 640, the second The connecting pin 642 and the regulating pin 644 are slidably housed. One end of the first connection pin 640 has a small diameter, and an oil chamber 646 is formed therein. The oil chamber 646 communicates with the oil path 650 via the branch path 648. Also regulate pin 64
4 is provided with a spring 652.
It is biased to 642 side. That is, when high-pressure oil is introduced into the oil chamber 646, the first and second connecting pins 640, 642 project against the spring force, press the restriction pin 644 to bridge the rocker arms to connect them, and When lowered, it is configured to return to the position shown by the urging force of the spring 652 to release the connection.

A hydraulic pressure switching mechanism 660 shown in the upper part of FIG. 5 is inserted between the oil passage 650 and the hydraulic pressure source (not shown). Hydraulic switching mechanism 660
Is provided with a spool valve 662, which has an inlet port 664 communicating with a hydraulic pressure source, and a communication passage 654 communicating with the oil passage 650.
To control the flow rate between the outlet ports 666 communicating with each other.
That is, when the spool valve 662 is in the illustrated closed position,
The pressure oil flowing from the inlet port 664 flows through the orifice hole 668 to the outlet port 666. At this time, a part of the pressure oil flows out through the bypass port 670, and the hydraulic pressure that flows into the oil passage 650 and acts on the oil chamber 646 is low. Therefore, the three rocker arms 614, 616, 118 swing separately and the low speed valve The intake / exhaust valves 54 and 56 are opened and closed at the timing.

The spool valve 662 is connected to the solenoid valve 680 via lines 672 and 674.
The pressure oil flowing from the inlet port 664 is sent to the solenoid valve 680 via the line 672, and when the valve is demagnetized and is in the illustrated closed position, it is closed there. Thus, the solenoid valve 680 opens when energized, and the pressure oil acts on the top of the spool valve 662 through the second line 674 to drive the spare valve to the open position indicated by the imaginary line. I do. As a result, the pressure oil flowing from the inlet port 664 flows into the orifice hole 6 described above.
In addition to 68, spool valve 662 as shown by the arrow (imaginary line)
Flows into the output port 666 through the gap formed between the annular concave portion and the storage wall surface, and flows into the oil passage 650. As a result, the oil pressure in the oil passage 650 increases, the connecting pins 640, 642 move, and the three rocker arms 614, 616, 618 are connected in a skewered manner to drive the intake and exhaust valves 54, 56 to open and close at high speed valve timing. In this high speed valve timing range, the overlap time and the lift amount increase as compared with the low speed valve timing range, so that the seating position of the intake valve is located at an angle further away from the TDC position. A hydraulic switch 600 is provided near the spool valve 662.

This variable valve timing control will be briefly described with reference to the flow chart of FIG. 6. In S10, the operation state of the engine including the engine speed Ne, the intake pressure Pba, the water temperature Tw, etc. is shown from the output of the sensor group described above. The parameters are read, and it is determined in S12 whether a prohibition condition of the valve timing switching is satisfied. When it is determined in S12 that the prohibition condition is not satisfied, the process proceeds to S14, in which a map stored in the ROM 66d is searched from the engine speed Ne and the intake pressure Pba (load) to determine a valve timing range.
FIG. 7 is an explanatory view showing this valve timing range,
As shown in the drawing, a switching point is set based on an appropriate engine speed and load, and the switching point is roughly classified into two regions of high and low. In S14, it is determined which of the low-speed valve timing and the high-speed valve timing should be selected from the sensor output.

Then, in S16, it is determined whether or not the determined valve timing is on the high speed side, and if it is on the high speed side, it advances to S18 to excite the solenoid valve 680 via the output circuit 72, and on the low speed side. Proceed to S20 and similarly through the output circuit 72, the solenoid valve 680
Is demagnetized, and the valve timing range determined in S22 or S24 is commanded and displayed with an appropriate flag. Since the charging efficiency or the combustion characteristics vary depending on the valve timing, the microcomputer 66 changes the ignition timing and the basic characteristics of the fuel injection control according to the determined timing.

Next, an embodiment of the present invention will be described with reference to the flow chart of FIG.

First, in S100, cylinder discrimination is performed based on the cylinder discrimination signal output from the crank angle sensor 48 described above, then in S102 it is determined from which flag the valve timing range is commanded, and then in S104, the valve timing range is determined. It is determined whether or not it has continued for a predetermined time.
This is performed by referring to the value of the timer counter that is activated each time the valve timing command is issued in S22 and S24 in the flow chart of FIG. This step is to confirm that the operation is stable when the valve timing is switched.

Subsequently, in S106, it is determined whether or not the vehicle is in the fail gate section. As shown in FIG. 4, this fail gate is for confirming the seating of the intake valve, and its seating position differs depending on the valve timing, but in the present embodiment, the seating position of the intake valve at the time of high speed valve timing is included. Within a predetermined crank angle range. When it is confirmed in S106 that the fail gate is for the high speed valve timing range, the process proceeds to S108, in which it is determined whether the determination result of the valve timing range is the high speed side. Next, the knock sensor output NOISE is compared with a predetermined reference value NOISEref. Specifically, this work involves setting a predetermined reference value NOISEref in the knock detection circuit described above.
The data is output to the inverting input terminal of the comparator means 70b via the D / A conversion circuit 70c. Here, the reference value NOISEref is the fourth
As shown in the figure, a value larger than the noise level VNOISE (or knock determination level) and smaller than the valve seating noise of the intake valve is previously obtained by experiments and stored in the ROM 66d. The output NOISE of the knock sensor 44 is input to the non-inverting input terminal of the comparator means 70b, and both are compared.

When it is determined in S110 that the sensor output NOISE is equal to or exceeds the reference value NOISEref, the intake valve is seated at the expected position, that is, as commanded by the microcomputer 66 in the variable valve timing mechanism. Since it means that the hydraulic mechanism is operating at high speed valve timing, it is determined that the mechanism is operating normally and the process proceeds to S112 where a down counter (described later) is set to a predetermined value. Exit the program.

Thus, in S110, the sensor output NOISE is the reference value NOISE.
When it is determined that the value falls below ref, the intake valve is not seated at the expected position, that is, the microcomputer 66 excites the solenoid valve 680 to switch the oil passage and connect the pins to achieve high-speed valve timing. Although it is instructed as described above, it means that the pin lock or the like is not operating as it is. Therefore, it is determined that the operation is abnormal and the down counter is decremented in S114, and the program is once terminated. Then, when it is confirmed that the counter value has reached zero in S116 at the time of starting the program from the next time onward, the process proceeds to S118, it is determined that the failure has occurred, and the fail operation described later is performed. Therefore, the above-mentioned down counter is for counting the number of times that the sensor output falls below the reference value,
The reason for this configuration is to ensure fail determination.

When it is determined in S108 that the valve is in the low speed valve timing range, the process proceeds to S120 and the subsequent steps, and an abnormality is determined from the reverse logic to the above logic. That is, the sensor output NOIS in S120
E and the reference value NOISEref are compared in the same way, but since the fail gate is set for high speed valve timing, the sensor output NOISE should be below the reference value NOISEref if the mechanism is operating normally. Yes, conversely sensor output NOIS
This is because it can be determined that the mechanism has failed if E is equal to or greater than the reference value NOISEref (S122 to S128).
When the result in S104 and S106 is negative, the program is immediately terminated.

The fail operation will be described here. When an abnormality is detected, switching of the valve timing is first prohibited, and the engine control value such as ignition timing and fuel injection is determined by the control value based on the valve timing of the locked side. . Alternatively,
Even when locked to the high speed valve timing, the control may be performed on the low speed valve timing side. Regarding fuel injection, in order to control the engine output, the engine speed is suppressed to an appropriate value, for example, below the value near the switching point shown in FIG. 7, and when the engine speed exceeds it, fuel cut is performed. May be. It should be noted that such a fail operation may be performed only for the abnormality detection cylinder, or may be performed for all cylinders including the abnormality detection cylinder. Further, in parallel with the fail operation described above, an appropriate warning display means may be connected to the microcomputer 66 to perform the warning operation.

In the above-mentioned embodiment, focusing on the fact that the seating position of the valve differs depending on the valve timing, the operation of the mechanism is monitored by detecting whether or not there is vibration above a predetermined value at the seating position, so failure detection is performed. Can be done quickly and accurately. Moreover, since the fail gate is fixed for high speed valve timing, the device can be simplified.

In the above-described embodiment, the fail operation is performed when the number of times of fail detection exceeds a predetermined value.
The fail operation may be performed based on the fail detection frequency per predetermined time.

Further, although the cylinders are discriminated and the failure is detected for each cylinder, it is possible to carry out without specifying the cylinders. Also, it is possible to use the exhaust valve although it is judged from the seating position of the intake valve, or the low speed valve. A fail gate for timing may be used, or both may be set separately. Further, although the reference value NOISEref is a fixed value, it may be variable according to the sensor output.

FIG. 9 is a flow chart similar to FIG. 8 showing the second embodiment of the present invention. This embodiment is premised on the case where the variable valve timing mechanism described above is provided with not only two types of valve timing regions, high speed and low speed, but also a medium speed region. That is, by changing the mechanism shown above appropriately, it is possible to change the mechanism between the low speed valve timing range and the high speed valve timing range.
It is assumed that the medium speed valve timing range is set as shown in Fig. 10.

Explaining with reference to FIG. 9, first, in S200, the valve timing range is determined, and in S202, it is confirmed that a predetermined time has passed in the same valve timing range, then in S204, the cylinder is determined, and in S206, the valve determined. Search the fail gate VTFSCR according to the timing range from ROM66d. In this embodiment, it is planned to set the fail gate individually for each valve timing. FIG. 11 shows the characteristic thereof, and as shown in the figure, the crank angle becomes larger as the speed becomes higher, that is, the seating position of the intake valve is set to be away from the TDC position. It is assumed that such characteristics are obtained in advance by experiments and stored in the ROM 66d. Subsequently, the reference value VTFSref is similarly retrieved from the ROM 66d according to the valve timing determined in S208.
Figure 12 shows its characteristics. Since the lift amount increases with increasing speed, the reference value is set to increase with increasing speed.

Then, in S210, it is determined whether or not the fail gate is in progress. If affirmative, in S212 and subsequent steps, the sensor output NOISE and the reference value VTFSref are compared in the same manner as in the first embodiment, and if the sensor output is greater than or equal to the reference value. If it is less than normal, it is determined to be abnormal (S214 to S220).

The present embodiment is particularly useful when there are three or more valve timing ranges. It should be noted that it is the same as in the first embodiment in that the reference value may be variable without specifying the cylinder.

In the first and second embodiments described above, the sensor output NOIS
When E is compared with the reference values NOISEref and VTFSref, the height is simply judged, but in this case, the pulse width or the number of pulses may be taken into consideration. That is, as shown in FIG. 13 (a), when transient noise occurs, the comparator means
70b generates one pulse, and when it is caused by valve seating noise, a plurality of pulses are usually generated as shown in FIGS. 14 (a) and 14 (b). It may be determined that the sensor output exceeds the reference value when occurs. In that case, instead of the number of pulses, an appropriate filtering method may be used, such as measuring the pulse width, for example, the elapsed time from the rising time of the first pulse to the falling time of the last pulse as shown in the figure.

Further, although the knock sensor is used to detect the valve seating noise in the first and second embodiments, it goes without saying that a vibration sensor may be provided separately from the knock sensor.

(Effect of the Invention) In the device according to claim 1, in the crank angle range set according to the characteristics instructed to the variable valve timing mechanism, the output level of the vibration level detecting means is compared with the reference level to obtain the variable valve timing. Since it is configured to detect the failure of the mechanism, it has an advantage that the failure detection of the variable valve timing mechanism is quick and accurate.

Further, in the apparatus according to the second aspect, the fail of the variable valve timing mechanism is detected for each cylinder, so that the fail operation can be quickly performed for the fail detected cylinder, and the valve timing control is performed for the normal cylinder. The high output that the variable valve timing mechanism is designed to continue can be utilized as much as possible.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is an explanatory diagram generally showing a valve timing control device for an internal combustion engine according to the present invention, and FIG. 3 shows details of a control unit in the device of FIG. Fig. 4 is an explanatory block diagram, Fig. 4 is an explanatory waveform diagram showing the operation of the knock detection and fail determination circuit therein, Fig. 5 is an explanatory sectional view showing the hydraulic switching device of the variable valve timing mechanism, and Fig. 6 is variable valve timing. 7 is an explanatory flow chart generally showing the control operation of the engine, FIG. 7 is an explanatory view showing the switching characteristic thereof, FIG. 8 is a flow chart showing the operation of the valve timing control device for an internal combustion engine according to the present invention, and FIG.
The figure shows the same flow as FIG. 8 showing the second embodiment of the present invention.
A chart, FIG. 10 is an explanatory diagram showing three types of valve timing ranges planned for the second embodiment, FIG. 11 is an explanatory diagram showing fail gate characteristics used in the second embodiment, and FIG. 12 is a second embodiment. Explanatory drawing showing the reference value characteristics used in the example, FIG. 13 (a)
(B) is an explanatory view showing a method of comparing the sensor output and the reference value,
Similarly, FIGS. 14 (a) and 14 (b) are explanatory views showing a method of comparing the sensor output and the reference value, and FIG. 15 is an explanatory view showing valve seating noise of the intake valve. 10 …… Internal combustion engine, 12 …… Intake pipe, 14 …… Throttle valve,
18 ... Cylinder head, 20 ... Intake port, 22 ... Combustion chamber, 24 ... Piston, 26 ... Spark plug, 28 ... Exhaust port, 30 ... Exhaust pipe, 32 ... Throttle position sensor, 34
...... Intake pressure sensor, 36 ...... Intake temperature sensor, 38 ...... Cylinder block, 40 ...... Cooling water passage, 42 ...... Water temperature sensor,
44 …… knock sensor, 46 …… distributor, 48…
… Crank angle sensor, 50 …… Vehicle speed sensor, 52 …… Control unit, 54 …… Intake valve, 56 …… Exhaust valve, 60 …… Variable valve timing mechanism, 62 …… Ignition device, 64 …… Level conversion circuit, 66 ... Microcomputer, 68 ... Waveform shaping circuit, 70 ... Knock detection circuit, 70a ... Filter means, 7
0b …… Comparator means, 70c …… D / A conversion circuit, 72,74
...... Output circuit, 600 ...... Hydraulic switch, 612 ...... Rocker shaft, 614,616,618 ...... Rocker arm, 632 ...... Hole, 63
4,636 ... Hole, 640,642 ... Connecting pin, 644 ... Regulating pin, 646 ... Oil chamber, 648 ... Branching path, 650 ... Oil path, 652 ...
... Spring, 654 ... Communication passage, 660 ... Hydraulic switching mechanism, 662 ...
… Spool valve, 664 …… Inlet port, 666 …… Outlet port, 668 …… Orifice hole, 670 …… Bypass port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 45/00 358 K F02P 17/00 (56) References Japanese Utility Model Application No. 60-68718 Specification attached to the application of Sho 61-183406) and the description attached to the application of Microfilm (JP, U) Jpn 60-71843 (Kaikai 61-186708) A micro film (JP, U) of the contents of the calligraphy and drawings

Claims (2)

[Scope of utility model registration request] 1. A valve of an internal combustion engine comprising a variable valve timing mechanism for selectively changing valve timing and / or lift amount of at least one of intake and exhaust valves among a plurality of characteristics in accordance with an operating state of the engine. In the timing control device, a. Vibration level detecting means for detecting the vibration level generated in the engine, b. Operating characteristic determining means for determining the operating characteristic instructed to the variable valve timing mechanism, c. Detecting the crank angle of the engine A crank angle detecting means for performing a crank angle range for fail determination of the variable valve timing mechanism according to a commanded operation characteristic by inputting outputs of the crank angle detection means and the operation characteristic determination means. Angular range setting means, e. The variable valve timing mechanism that receives the output of the operation characteristic determination means, and responds to the commanded operation characteristics. Reference level setting means for setting a reference level for failure determination, and f. The reference level setting means and the vibration level detecting means,
And a fail detecting means for inputting an output of the crank angle range setting means, comparing an output value of the vibration level detecting means with the reference level in the crank angle range, and detecting an abnormality of the variable valve timing mechanism. A characteristic valve timing control device for an internal combustion engine. 2. The internal combustion engine comprises a plurality of cylinders, g. Cylinder discrimination means for discriminating cylinders, wherein the fail detection means inputs the output of the cylinder discrimination means, and The valve timing control device for an internal combustion engine according to claim 1, wherein an abnormality of the valve timing mechanism is detected for each cylinder.