JP2943042B2 - Function diagnosis device for variable valve mechanism of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine having a variable valve mechanism for switching the opening and closing characteristics of an intake / exhaust valve according to operating conditions, and more particularly to an apparatus for diagnosing the operating state of the intake / exhaust valve mechanism.

[0002]

2. Description of the Related Art Conventionally, a lift characteristic (opening characteristic) of an intake valve or an exhaust valve has been changed, for example, by using a high-speed cam for the purpose of achieving both high torque characteristics during low-medium-speed operation and improvement in output during high-speed operation. It is known that the low-speed cam and the low-speed cam are used differently depending on the operating conditions, thereby controlling the intake / exhaust timing or the intake / exhaust amount (JP-A-63-167016, JP-A-63-163163). -5780
No. 5, JP-A-5-171909, etc.).

[0003] In recent years, in internal combustion engines, it has been required to diagnose the functions of devices relating to exhaust emission performance. The variable valve mechanism is also subject to function diagnosis because if it does not operate normally, it will cause a deterioration in exhaust emissions. 2. Description of the Related Art A conventional function diagnosis device for a variable valve mechanism employs a method of directly or indirectly diagnosing a function state of a variable valve mechanism by attaching a sensor for detecting oil pressure to a movable portion or a hydraulic path.

[0004]

However, in the function diagnosis apparatus for a conventional variable valve mechanism of an internal combustion engine, a method of diagnosing the function of the variable valve mechanism by oil pressure is used, so that the processing of the variable valve mechanism is difficult. Further, it is difficult to detect a change in filling efficiency due to a change in valve timing, which is an original function, and it is necessary to diagnose the function of the variable valve mechanism more accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a function diagnosing apparatus for a variable valve mechanism of an internal combustion engine, which can more accurately diagnose the function of the variable valve mechanism. And

[0006]

SUMMARY OF THE INVENTION For this reason, the present invention has been described with reference to FIG.
As shown in the figure, in an internal combustion engine equipped with a variable valve mechanism for switching the opening and closing timing of intake and exhaust valves according to engine operating conditions, cam angle detection for detecting a rotation angle of a cam shaft
Means and crank angle detection for detecting a rotation angle of a crankshaft
Means and the detected camshaft rotation angle and crankshaft rotation
Based on the turning angle, set the closing timing of the intake and exhaust valves,
A closing signal that outputs a valve closing signal that is high during the valve closing time
Valve signal output means, engine vibration detection means for detecting engine vibration, and a valve closing signal output by the valve closing signal output means
A seating sound extracting means for extracting a seating sound frequency component of the intake / exhaust valve from the engine vibration detected by the engine vibration detecting means when is at a high level; and the valve closing signal output means.
From the high level to the low level
Operating state diagnosing means for diagnosing the operating state of the variable valve mechanism based on the intensity of the frequency component of the seating sound of the intake / exhaust valve extracted by the seating sound extracting means when the vehicle falls. I did it.

The variable valve mechanism may switch between opening and closing timings of intake and exhaust valves by switching between a low speed cam and a high speed cam.
Further, the seating sound extraction unit, in closing timing of the intake and exhaust valves is switched variable valve timing, respectively, to extract the seating sound frequency, operating condition diagnosis means, these two closed
Compare the strength of the sitting sound frequency component extracted at the valve timing ,
The diagnosis may be performed with the valve closing timing having the greater strength as the actual valve closing timing.

The seating sound extracting means extracts a seating sound frequency at a valve closing timing during low-speed cam or high-speed cam control of the intake / exhaust valve.
The intensity of the sitting sound frequency component extracted at the closing timing of the exhaust valve is compared with a predetermined level, and when the intensity of the sitting sound frequency component is larger than the predetermined level, the closing timing under control is diagnosed as the actual closing timing. May be performed.

[0009]

According to the above structure, in the function diagnostic device for the variable valve mechanism of the internal combustion engine according to the first aspect of the present invention, when the valve is closed.
When the signal from the period signal output means is at a high level ,
The intensity of the sitting sound frequency component generated when the exhaust valve is closed is extracted by the sitting sound extracting means, and the closing timing of the variable valve mechanism is determined based on the intensity of the sitting sound frequency component. Therefore, the operating state diagnosis means performs the intake / exhaust operation based on the actual valve closing timing and the control command to the variable valve mechanism of the intake / exhaust valve.
By comparing the closing timing of the exhaust valve with the closing timing of the exhaust valve, it is possible to diagnose whether or not the operating state of the variable valve mechanism is correct.

Since the function of the variable valve mechanism is diagnosed by detecting the intensity of the frequency component generated when the intake / exhaust valve is actually seated, the function of the variable valve mechanism can be diagnosed more accurately. Becomes In the function diagnosis device for a variable valve mechanism of an internal combustion engine according to the second aspect of the present invention, the variable valve mechanism switches between a low speed cam and a high speed cam. The strength of the frequency component of the seating sound is extracted to determine whether the operating state of the variable valve mechanism is correct.

Further, in the function diagnosis apparatus for a variable valve mechanism of an internal combustion engine according to the third aspect of the present invention, the strengths of the frequency components of the seating sound extracted at the two valve closing times are compared with each other. The valve closing timing is diagnosed as the actual valve closing timing. In the function diagnosis device for a variable valve mechanism of an internal combustion engine according to the invention of claim 4, the intake and exhaust valves under control are controlled.
The intensity of the frequency component of the sitting sound extracted at the valve closing timing is compared with a predetermined level, and when the intensity of the sitting sound frequency component is greater than the predetermined level, the valve closing timing under control is diagnosed as the actual valve closing timing. .

[0012]

Embodiments of the present invention will be described below. FIG. 2 is a block diagram schematically showing the system configuration of the present embodiment.
In FIG. 2, the engine, which is an internal combustion engine, is provided with a variable valve mechanism 101 for selectively switching a valve opening characteristic (lift characteristic) to a plurality of preset types. The variable valve mechanism 101 is a hydraulic variable mechanism that switches a valve opening characteristic by operating hydraulic pressure.

The control unit 102 incorporates a microcomputer, and controls the supply of operating oil pressure to the variable valve mechanism 101 to drive and control the switching valve 103 (hydraulic control valve). Here, a specific example of the variable valve mechanism 101 is shown in FIGS. Describing this, each cylinder is provided with a single rocker arm 1 corresponding to two intake valves V. The base end of the rocker arm 1 is
The rocker arm 1 is swingably supported by a cylinder head via a hollow main rocker shaft 3 common to each cylinder.
Each of the two forked ends abuts on the stem top of the intake valve V.

The rocker arm 1 is formed substantially bifurcated in plan view, and the rocker arm 1 is provided with a single free cam follower 2 substantially above the center thereof. And FIG.
, On both sides of the free cam follower 2
Rollers 11, 11 with which 1, 1 abut are provided. The base end of the free cam follower 2 is supported by the rocker arm 1 via a sub rocker shaft 16 so as to be swingable (relatively rotatable). The free cam follower 2 does not have a portion that comes into contact with the intake valve V, and a cam follower portion 2A that is in sliding contact with the high-speed cam 22 is formed at the tip thereof so as to protrude in an arc shape.

A recess 27 is formed below the free cam follower 2 to slidably fit a spring retainer 29. The spring retainer 29 has a base end supported by the bottom surface of the recess 27. The elastic spring force of the coil spring 26 makes contact with the rocker shaft 3. Further, the free cam follower 2 has a stepped portion 2B with which a later-described lever member 7 is engaged, and an inclined portion 2C connected thereto, below the cam follower portion 2A. A lever member 7 is provided below the rocker arm 1 so as to be swingable by a pin 6 on the side of the rocker shaft 3.

On the upper side of the lever member 7, a projection 7 is provided.
A is integrally formed, and is urged by a return spring 9 and a spring retainer 10 housed in a recess 8 formed in the rocker arm 1 in a direction in which the engagement with the free cam follower 2 is released. On the other hand, the lower end of the lever member 7 has an operating plunger 31 driven by supply of operating hydraulic pressure to a hydraulic chamber 34 provided in the rocker arm 1.
Is in contact.

The oil passage for guiding the operating oil pressure to the hydraulic chamber 34 is
It is provided through the inside of the rocker arm 1 and the main rocker shaft 3. The rocker arm 1 is formed with a through hole 41 having one end opened to the hydraulic chamber 34 and the other end penetrating a bearing surface for the main rocker shaft 3. Also,
An oil gallery 42 is formed in the main rocker shaft 3 in the axial direction. The oil gallery 42 communicates with the through hole 41 of the rocker arm 1 through the through hole 43.

The discharge pressure of an oil pump (not shown) driven by an engine is selectively guided to the oil gallery 42 via a switching valve 103 whose operation is controlled by the control unit 102. Low speed cam 2
The high-speed cam 22 and the high-speed cam 22 therebetween are integrally formed on a common camshaft 20 to satisfy a valve lift characteristic (opening characteristic) required at low engine speed and high engine speed. Are formed in different shapes.
That is, the high-speed cam 22 has a cam profile that makes at least one of the valve lift amount and the valve open period larger than the low-speed cam 21. In the present embodiment, both the valve lift amount and the opening period are increased, and two types of valve opening characteristics can be switched by selectively using the high-speed cam 22 and the low-speed cam 21. I have.

According to the variable valve mechanism 101 having the above structure,
In a state where the operating oil pressure is not supplied to the hydraulic chamber 34 (a hydraulic relief state by the switching valve 103), the rocker arm 1 swings according to the cam profile of the low speed cam 21 to open and close each intake valve V. At this time, the free cam follower 2
Is swung by the high-speed cam 22, but the spring 9
The lever member 7 is at the position shown by the solid line in FIG. Therefore, even if there is an input from the free cam follower 2, the movement of the rocker arm 1 is not affected only by the bending of the spring 26.

On the other hand, when the operating oil pressure is supplied to the hydraulic chamber 34, the operating plunger 31 swings the lever member 7 against the return spring 9 to bring it to the position shown by the broken line in FIG. . In this state, the rocker arm 1 and the cam follower 2 are connected and integrated as a result of the end of the lever member 7 being engaged with the step 2B of the free cam follower 2 and swinging about the main rocker shaft 3. become.

Since the high-speed cam 22 is formed so that both the valve opening angle and the valve lift are larger than the low-speed cam 21, the free cam follower 2 is integrated with the rocker arm 1. When rocking, rocker arm 1
Roller 11 is lifted from the low speed cam 21, and each intake valve V is driven to open and close according to the profile of the high speed cam 22, and both the opening angle and the lift amount are increased.

On the other hand, when switching from the high-speed cam 22 to the low-speed cam 21, the hydraulic pressure guided to the hydraulic chamber 34 is reduced by controlling the switching valve 103, and the lever member 7 and the operating plunger are returned by the elastic restoring force of the return spring 9. 31 is moved to the original position (the position indicated by the solid line in FIG. 5), and the locker arm 1 is released. Thus, the switching valve
By selectively supplying the operating oil pressure to the hydraulic chamber 34 by the valve 103, the valve opening characteristic adapted to the low speed range according to the profile of the low speed cam 22 and the opening speed of the low speed cam 22 according to the profile of the high speed cam 21 are increased. Any one of the valve opening characteristics suitable for a high speed range where the angle and the lift amount are large can be switched and selected.

In this embodiment, the switching between the high-speed cam 21 and the low-speed cam 22 depends on whether or not the rocker arm 1 and the cam follower 2 are connected by the swing of the lever member 7 as described above. Although the configuration has been described, the cam switching mechanism is not limited to the above. For example, Japanese Patent Application Laid-Open Nos. 63-167016 and 63-5
As disclosed in Japanese Patent Publication No. 7805 or the like, a high-speed rocker arm and a low-speed rocker arm are selectively connected to each other by engaging and disengaging a fitting hole and a plunger in a direction parallel to the rocker shaft. It is also possible to adopt a configuration in which switching between the cam for low speed and the cam for low speed is performed.

Further, instead of using a plurality of cams, it is possible to mount a cam sprocket capable of controlling the cam phase with a constant operating angle on the camshaft, and to switch the intake valve opening / closing timing to an appropriate timing for each speed range. Variable valve timing control device (“New vehicle manual (FGY32-
1), pages B-44 to B-45, edited and published by Nissan Motor Co., Ltd., issued in August 1991), and the configuration of the variable valve mechanism 101 is not limited.

Next, the configuration of the function diagnostic device for the variable valve mechanism according to the present invention will be described. In FIG. 2, an engine 104 includes a vibration sensor 105 as engine vibration detecting means for detecting vibration, and a cam sensor as cam angle detecting means for detecting a rotation angle of a cam shaft and outputting a REF signal. And an angle sensor 10 as crank angle detecting means for detecting the angle of the crankshaft 107 and outputting a POS signal.
8 and are attached, and the detection signals of these sensors are input to the control unit 102.

The control unit 102 includes an analog filter, a digital filter, and an FF for detecting the frequency component of the detection signal of the vibration sensor 105 and the intensity thereof.
A frequency detection unit 201 as a seating sound extraction unit having T, Wavelet, etc., and a suction / reception at the time of switching between a high speed cam and a low speed cam, based on the REF signal output from the cam sensor 106 and the POS signal output from the angle sensor 108. Valve closing signal output means for setting a closing timing of the exhaust valve and outputting a valve closing window pulse (hereinafter simply referred to as a pulse) ;
And a valve closing timing detecting section 202.

A microcomputer built in the control unit 102 includes a valve closing timing detecting section 202.
The function of the variable valve mechanism 101 is diagnosed on the basis of the valve closing window pulse output from the controller and the frequency component and intensity of the detection signal of the vibration sensor 105 detected by the frequency detector 201. This processing is performed by software.

Next, the function diagnosis processing of the variable valve mechanism 101 will be described based on two embodiments. First, in the first embodiment, the intensity of the frequency component of the seating sound is extracted near two valve closing times in which the intake and exhaust valves are controlled to be switched, and the intensities of the two frequency components are compared. The function is diagnosed.

FIGS. 7 and 8 are flowcharts of the first embodiment, and FIG. 9 is a timing chart of the first embodiment.
In the case of the first embodiment, the valve closing timing detecting section 202
Thereafter, as shown in FIG. 9, two pulses, that is, a pulse A having a Hi level near the valve closing timing during the high-speed cam switching control, and a Hi level near the valve closing timing during the low-speed cam switching control, are obtained. And pulse B.

In the step 1 of FIG. 7 (denoted by "S" in the figure, the same applies hereinafter), a pulse as shown in FIG. 9 output from the valve closing timing detecting section 202 is Hi.
Check if it is a level. When the pulses A and B are at the low level, this routine is terminated. When the pulse A or the pulse B is at the Hi level, the process proceeds to step 2 where the frequency detection unit 201 performs a frequency analysis.

When the pulse A or the pulse B changes from Hi level to L
When the signal has fallen to the ow level, the process proceeds to step 3 → 4, and whether the fall is the fall of the pulse A corresponding to the high-speed cam operation period or the fall of the pulse B corresponding to the low-speed cam operation period Judge. And
If it is the falling edge of the pulse A, the process proceeds to step 5 and the result of the frequency analysis is stored in the microcomputer A, for example.
If it is stored in the register and the pulse B is falling, the process proceeds to step 6, where the frequency analysis result is stored in the B register, and this routine ends.

Next, in step 11 of FIG. 8, the intensity of the frequency component stored in the A register and the intensity of the frequency component stored in the B register are compared. If the value stored in the A register is equal to or greater than the value stored in the B register, steps 11 → 12
Proceed to. When the high-speed cam control is being performed, the intensity of the frequency component due to the operation of the intake / exhaust valve is increasing during the high-speed cam control.
The intake and exhaust valves are operating normally and the variable valve mechanism
Judge that the function of 101 is normal.

If the value stored in the A register is smaller than the value stored in the B register, and the low speed cam control is being performed, similarly, the process proceeds to steps 11 → 15 → 13 to determine that the function diagnosis is OK. I do. On the other hand, if the value stored in the A register is smaller than the value stored in the B register and high speed cam control is being performed, steps 11 → 12 → 1
Proceed to 4 and determine that the function diagnosis is NG. Also, if the value stored in the A register is larger than the value stored in the B register and the low speed cam control is being performed, steps 11 → 15
→ Proceed to 14, and judge that the function diagnosis is NG.

This routine corresponds to the operating state diagnostic means. According to such a configuration, the pulses A and B near the valve closing period at the time of the high-speed cam control command and at the time of the low-speed cam control command, respectively.
Is generated, and when two pulses A and B are input, the frequency analysis of the seating sound of the intake and exhaust valves is performed based on the detection signal of the vibration sensor 105, and the two frequency analysis results are compared to perform a function diagnosis. By doing so, the function diagnosis is performed based on the intensity of the frequency component generated when the intake / exhaust valve is actually seated, so that the function diagnosis can be performed more accurately, and the diagnostic performance is improved. In addition, the cost can be reduced since a hydraulic sensor having a complicated mechanism is not required.

Next, a second embodiment will be described. This apparatus extracts a frequency component of a sitting sound near a valve closing time of an intake / exhaust valve controlled to be switched by a variable valve mechanism and determines whether or not the intensity of the sitting sound frequency component is equal to or higher than a predetermined level. By examining the function, the function diagnosis of the variable valve mechanism is performed.

The configuration of the second embodiment is the same as that of the first embodiment, as shown in FIG. 2, but the valve closing timing detecting section 202 outputs the high-speed cam or low-speed cam switching control. One pulse is output with the Hi level near the valve closing timing. 10 and 11 are flowcharts of the second embodiment, and FIG. 12 is a timing chart of the first embodiment. Steps performing the same operations as those in the first embodiment are given the same step numbers. .

During the period when the intake / exhaust valve is close to the valve closing time and the Hi-level pulse is being output from the valve closing timing detecting unit 202, the frequency detecting unit 201 extracts the frequency component at the time of the actual valve closing ( Step 2), the analysis result is input to the register when the pulse falls (step 3 → 21). For example, in FIG. 12, a pulse of Hi level is output in a period T ₁ through T _3. Period T
Reference numeral ₁ denotes, for example, a low-speed cam control as a control command, and high-speed cam control during periods T ₂ and T ₃ , and a frequency analysis result when a pulse is output during each period is stored in a register.

Next, based on the analyzed frequency analysis results,
The function diagnosis is performed according to the flowchart of FIG. 11 and the timing chart of FIG. In the period T ₁ during the low-speed cam control and the period T ₂ during the high-speed cam control, when the pulse is output, the intensity of the frequency component stored in the register is equal to or higher than a predetermined level. Proceed to step 33 to diagnose that the function is normal.

On the other hand, in the period T _3, pulse, but is output at closing timing near the high-speed cam control, the strength of the stored frequency component in a register has a predetermined level or less, in which case , Proceed to step 34, and perform function diagnosis
Is determined. As described above, even if the pulse C is output in the vicinity of the valve closing timing during the high-speed cam or low-speed cam switching control, and whether or not the frequency component during that period is equal to or higher than the predetermined level, the variable C Function diagnosis can be performed.

[0040]

As described above, according to the present invention, in the function diagnosis apparatus for a variable valve mechanism of an internal combustion engine according to the first aspect of the present invention, the frequency component of the seating sound generated when the intake / exhaust valve is closed. Extract the intensity of the
By diagnosing the actual valve closing timing by comparing it with the valve closing timing at the time of the control command, the function of the variable valve mechanism is diagnosed based on the intensity of the frequency component generated when the intake and exhaust valves are actually seated. The function of the variable valve mechanism can be diagnosed more accurately, the diagnostic performance is improved, and the cost can be reduced because a complicated mechanism is not required.

In the function diagnosis device for a variable valve mechanism of an internal combustion engine according to the second aspect of the present invention, the strength of the seating sound frequency component is extracted only during low-speed cam control and high-speed cam control, so that it is accurate and easy. The function of the variable valve mechanism can be diagnosed. In the function diagnosing device for a variable valve mechanism of an internal combustion engine according to the third aspect of the present invention, when the two
The function of the variable valve mechanism can be accurately and easily diagnosed by comparing the intensities of the sitting sound frequency components extracted in the period .

In the function diagnosis device for a variable valve mechanism of an internal combustion engine according to the present invention, the intensity of the frequency component of the seating sound extracted at the closing timing of the intake / exhaust valve under control is compared with a predetermined level. Thus, the function of the variable valve mechanism can be diagnosed accurately and easily.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a system block diagram showing one embodiment of the present invention.

FIG. 3 is a view showing a variable valve mechanism of the embodiment.

FIG. 4 is a view showing a variable valve mechanism according to the embodiment (IV- in FIG. 3);
IV cross section).

FIG. 5 is a view showing a variable valve mechanism according to the embodiment (V- in FIG. 4);
V sectional view).

FIG. 6 is a view showing a variable valve mechanism according to the embodiment (VI- in FIG. 4);
VI cross section).

FIG. 7 is a flowchart illustrating a function diagnosis process according to the first embodiment;

FIG. 8 is a flowchart of the above.

FIG. 9 is a timing chart of the function diagnosis device of the first embodiment.

FIG. 10 is a flowchart illustrating a function diagnosis process according to the second embodiment.

FIG. 11 is a flowchart of the same.

FIG. 12 is a timing chart of the function diagnosis device according to the second embodiment.

[Explanation of symbols]

 101 Variable Valve Mechanism 102 Control Unit (C / U) 105 Vibration Sensor 106 Cam Sensor 108 Angle Sensor 201 Frequency Detector 202 Valve Close Timing Detector

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01L 13/00 301 F01L 1/46 F02B 77/08

Claims (4)

(57) [Claims] In an internal combustion engine provided with a variable valve mechanism for switching the opening and closing timing of intake and exhaust valves according to engine operating conditions, a cam angle detecting means for detecting a rotation angle of a camshaft, and a rotation angle of a crankshaft. A crank angle detecting means for detecting the rotation angle of the camshaft and the detected rotation angle of the crankshaft;
Then, set the closing timing of the intake and exhaust valves,
Signal output that outputs a high level valve closing signal during the period
Force means, engine vibration detecting means for detecting engine vibration, and valve closing signal output by the valve closing signal output means.
At the time of the level, the seating sound extracting means for extracting the seating sound frequency component of the intake / exhaust valve from the engine vibration detected by the engine vibration detecting means, and the valve closing signal output by the valve closing signal output means. Yes
Operating state diagnosing means for diagnosing the operating state of the variable valve mechanism based on the intensity of the frequency component of the seating sound of the intake / exhaust valve extracted by the seating sound extracting means when falling from the low level to the low level ; A function diagnosis device for a variable valve mechanism of an internal combustion engine, comprising: Wherein said variable valve mechanism, by switching the low speed cam and the high speed cam, the internal combustion engine according to claim 1, characterized in that for switching the opening and closing timing of the intake and exhaust valves Function diagnosis device for variable valve mechanism. 3. The seating sound extracting means , at the closing timing of the intake and exhaust valves switched by the variable valve mechanism, respectively.
The seating sound frequency is extracted, and the operating state
The strength of the sitting sound frequency component extracted at the two valve closing timings is compared, and diagnosis is performed with the valve closing timing having the greater magnitude as the actual valve closing timing. Function diagnosis device for a variable valve mechanism of an internal combustion engine. 4. A seating sound extracting means for extracting a seating sound frequency at a valve closing timing during low-speed cam or high-speed cam control of the intake / exhaust valve, and an operating state diagnostic means for closing the intake / exhaust valve under control. The strength of the sitting sound frequency component extracted at the valve timing is compared with a predetermined level, and when the strength of the sitting sound frequency component is larger than the predetermined level, diagnosis is performed with the valve closing timing under control as the actual valve closing timing. The function diagnosis device for a variable valve mechanism of an internal combustion engine according to claim 1 or 2, wherein: