JP2002285875A - Variable valve timing engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a clogging condition of an EGR passage for solving a lack of exhaust gas in a variable valve timing engine. SOLUTION: The EGR passage 8 is arranged for refluxing exhaust gas from an exhaust pipe 5 of the engine 1 to an intake system by intake negative pressure. An intake cam 24 opening/closing an intake valve 6 is arranged via a VTC 27 (phase angle regulating means) so that the phase angle of the intake cam 24 is regulated freely. According to the increase/decrease of an exhaust gap reflux amount, the phase angle of the intake cam 24 is regulated for reducing the generation of NOx.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing engine provided with an exhaust gas recirculation device for reducing a part of exhaust gas to a combustion chamber of the engine to reduce NOx.

[0002]

2. Description of the Related Art A conventional exhaust gas recirculation device of this type is, for example, disclosed in Japanese Patent Application Laid-Open No. H11-125126, in which an exhaust gas recirculation passage (hereinafter, referred to as an EGR passage) which connects an intake passage and an exhaust passage to each other. And an exhaust gas recirculation valve (hereinafter, referred to as an EGR valve) for opening and closing the EGR passage. The EGR valve is disposed in the EGR passage. The EGR valve opens and closes the EGR passage between fully open and fully closed,
A valve that controls the amount of exhaust gas recirculated from the exhaust passage to the intake passage.The valve is opened or closed or its opening is adjusted based on the engine load, engine speed, cooling water temperature, etc., and flows into the combustion chamber of the engine according to the operating state. To recirculate exhaust gas.
There is also known a variable valve timing engine having phase angle adjusting means for adjusting a mutual phase angle between an exhaust cam for opening and closing an exhaust valve and an intake cam for opening and closing an intake valve.

[0003]

When a part of the exhaust gas is recirculated to the combustion chamber of the engine through the EGR passage, a rapid rise in the combustion speed and heat of the air-fuel mixture in the combustion chamber is suppressed, and the combustion temperature is reduced. Since it is reduced, there is an advantage that NOx is reduced. However, when unburned fuel (HC) in the exhaust gas adheres to the surfaces of the EGR passage and the EGR valve and is gradually carbonized by the high-temperature heat, the EGR for the EGR passage or the EGR valve is reduced.
The GR passage may be clogged or clogged, causing a problem in the recirculation of the EGR gas and deteriorating NOx. Also,
Once the adhered carbon is peeled off for some reason, the flow rate in the EGR passage also changes.
There is a problem that Ox deteriorates. Further, when the amount of overlap in which both the intake valve and the exhaust valve are open is changed by adjusting the phase angle adjusting means, the internal recirculation amount of the exhaust gas also increases. Therefore, it was difficult to control the optimal amount of EGR according to the operating state because the internal recirculation amount of the exhaust gas was not controlled in accordance with the condition.

The present invention has been made in view of the above circumstances, and a purpose thereof is to detect a clogged state of an EGR passage,
An object of the present invention is to eliminate excess / deficiency of the recirculation amount of exhaust gas and reduce NOx.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object.
A variable valve timing engine having an EGR passage for recirculating exhaust gas from an exhaust system to an intake system, and a phase angle adjusting means for adjusting a mutual phase angle between an exhaust cam for opening and closing the exhaust valve and an intake cam for opening and closing the intake valve. The present invention provides a variable valve timing engine including control means for controlling the phase angle adjusting means according to the amount of exhaust gas recirculated through the EGR passage. That is, once the attached carbon is separated for some reason, the flow rate in the EGR passage changes. However, the control means operates the mutual phase angle between the intake valve and the exhaust valve in the advance or retard direction in accordance with the recirculation amount of the exhaust gas, and operates the internal phase of the exhaust gas in accordance with the exhaust gas recirculation amount in the EGR passage. Since the recirculation amount is increased or decreased, the recirculation amount of the exhaust gas as a whole has a flow rate corresponding to the operating state of the engine. Therefore, it is easy to control the optimal EGR amount according to the operating state.

According to a second aspect of the present invention, an EGR passage for recirculating exhaust gas from an exhaust system to an intake system, and a mutual phase angle between an exhaust cam for opening and closing an exhaust valve and an intake cam for opening and closing an intake valve are adjusted. A variable valve timing engine having a phase angle adjusting means for adjusting an overlap amount in which both the intake valve and the exhaust valve are open, wherein the phase angle adjusting means is controlled in accordance with a recirculation amount of the exhaust gas in the EGR passage. Control means for controlling the phase angle adjustment amount by the control means when the overlap amount based on the exhaust gas recirculation amount in the EGR passage is larger than the overlap amount based on the operation state of the engine. A valve timing engine is provided. According to such a configuration,
Since the mutual phase angle between the intake cam and the exhaust cam is adjusted in the advancing or retarding direction in accordance with the recirculation amount of the exhaust gas and the internal recirculation amount of the exhaust gas is adjusted, the recirculation amount of the exhaust gas as a whole is Becomes the flow rate corresponding to the operating state of the engine, and it becomes easy to control the optimal EGR amount according to the operating state. When the overlap amount between the intake valve and the exhaust valve based on the exhaust gas recirculation amount in the EGR passage is larger than the overlap amount between the intake valve and the exhaust valve based on the operation state of the engine,
The control means limits the amount of phase angle adjustment, thereby preventing the operating state of the engine from deteriorating.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a clogging detecting means for detecting the clogging of the EGR passage is provided, and the control means controls the control means based on the clogging state of the EGR passage. An object of the present invention is to provide a variable valve timing engine configured to control the phase angle adjusting means. That is, when the unburned fuel (HC) in the exhaust gas adheres to the surfaces of the EGR passage and the EGR valve and is gradually carbonized by high-temperature heat, the EGR passage or the EGR
The opening / closing portion of the EGR passage for the valve may be clogged or blocked, but the control means operates the phase angle adjusting means in response to the clogging to adjust the internal recirculation amount of the exhaust gas. The recirculation amount of the gas as a whole is a flow rate corresponding to the operating state of the engine.

[0008] Further, the invention according to claim 4 is the invention according to claim 3.
In the invention described above, it is an object of the present invention to provide a variable valve timing engine configured so that the clogging detecting means detects the clogging of the EGR passage at the time of fuel cut. According to such a configuration, the clogging of the EGR passage is accurately detected without deteriorating the engine emission.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 shows a system of a four-stroke engine according to the present invention, and FIG. 2 shows the structure of a drive system and a valve train of the engine.

In the drawing, 1 is an engine, 2 is a cylinder block, 3 is a cylinder head, 4 is an intake pipe (including an intake port) that partitions an intake passage, and 5 is an exhaust pipe (including an exhaust port) that partitions an exhaust passage. ). An intake valve 6 is attached to an intake port of the engine 1 so as to be openable and closable, and an exhaust valve 7 is attached to an exhaust port so as to be openable and closable. The intake pipe 4 and the exhaust pipe 5 are communicated with each other by an EGR passage 8 for exhaust gas recirculation.
An EGR valve 9 for adjusting the exhaust gas recirculation amount is disposed at a communication point between the R passage 8 and the exhaust pipe 5, specifically, at the EGR port 12.

As the EGR valve 9, either an electric type or a negative pressure type is used. In the present embodiment, a solenoid type is used. One end 8a of the EGR passage 8 communicates with the exhaust pipe 5 upstream of the three-way catalyst C, and the other end 8b communicates with the intake pipe 4 downstream of the throttle valve 36. This E
The GR passage 8 is provided with an EGR valve 9 for controlling the exhaust gas recirculation amount and a volume chamber 8c. The EGR valve 9 is a solenoid 9
a solenoid 9a is connected to the ECU 15, and the opening degree of the EGR valve 9 is controlled by the ECU 1.
5 so that it can be changed linearly by a control signal from the control unit 5. The EGR valve 9 includes the EGR valve 9.
A lift sensor 42 is provided in order to detect the valve opening degree of the lift sensor 42. The detection signal of the lift sensor 42 is output to the ECU 15. The ECU 15 determines an engine operating state based on engine parameter signals from various sensors described later and the like, and the valve opening of the EGR valve 9 set according to the absolute pressure PB in the intake pipe 4 and the engine speed NE. Command value and E detected by the lift sensor 42.
A control signal is output to the solenoid 9a so as to make the deviation from the actual valve opening of the GR valve 9 equal.

As shown in detail in FIG. 2, an intake camshaft 17 and an exhaust camshaft 18 are rotatably supported on the cylinder head 3. Double camshaft 1
The driven sprockets 19, 20 and 7, and the driving sprocket 22 of the crankshaft 21 are connected by an endless timing chain 23, and the two camshafts 17, 18 per two rotations of the crankshaft 21.
Are driven to rotate at a rate of one rotation.

The intake camshaft 17 has an intake valve 6,
The intake cam 24 for opening and closing the 6 is integrally formed,
An exhaust cam 25 for opening and closing the exhaust valves 7 is integrally formed with the exhaust camshaft 18. Further, in order to rotate the intake camshaft 17 relatively to the driven sprocket 19 and change the phase angle of the intake cam 24 with respect to the crankshaft 21, a phase angle is set at one end of the intake camshaft 17. Adjustment means (hereinafter referred to as VTC) 27 is attached.

FIG. 3 shows the inside of the VTC 27, and FIG.
Shows a cross section taken along line IV-IV in FIG. As shown in FIGS. 3 and 4, the intake camshaft 1 is provided in the housing 27a.
A vane (rotor) 29 for adjusting the phase angle of the rotary member 7 is accommodated. The housing 27a is fixed to the driven sprocket 19 by a bolt B1, and the vane 29 is
Thus, it is fixed to one end of the intake camshaft 17. As shown in FIG. 4, a plurality of vane portions 29b are formed on the boss portion 29a of the vane 29 so as to project outward from the outer peripheral surface. A partition wall 27c for partitioning the inside of the housing 27a in the circumferential direction to form a plurality of hydraulic chambers is formed on an inner peripheral wall 27b of the housing 27a. An oil passage is formed through the vane portion 29b to rotate the vane 29 by switching between the advance direction and the retard direction.

One oil passage is used as an advance oil passage 29c for rotating the vane 29 to the advance side, and the other oil passage is used as a retard oil passage 29d for rotating the vane in the retard direction. It is connected to an oil pump (not shown) via a valve (described later) 28. For this reason, while supplying the hydraulic oil to the hydraulic chamber on the advance side (hereinafter referred to as the advance chamber) 30 around the vane 29, the same amount of hydraulic oil is supplied from the hydraulic chamber 31 on the retard side (hereinafter, the retard chamber). Upon discharge, the intake camshaft 17 is rotated in the advance direction within the range of the adjacent partition walls 27c, 27c,
Conversely, if the same amount of oil is discharged from the advance chamber 30 while supplying hydraulic oil to the retard chamber 31, the adjacent partition walls 27c, 27
The intake camshaft 17 is turned to the retard side within the range of c. Accordingly, the intake cam 24 can be advanced from the retard position indicated by the dotted line a in FIG. 5 to the advanced position indicated by the solid line b, or can be retarded from the advanced position to the retard position.
In FIG. 3, reference numeral ST denotes a stopper for restricting the rotation of the vane 29, and is released by the pressure of the working oil supplied through an oil passage (not shown).

FIG. 6 shows the ECU 15, various sensors for detecting the operating state of the engine, and the hydraulic control valve 28. The hydraulic control valve 28 is composed of a linear solenoid valve having a drive coil (not shown) and a spool (not shown) driven by the drive coil.
The position of the spool is changed in accordance with the output duty ratio (output control value) of the current supplied from 15 to the drive coil. When the output duty ratio (output control value) output from the ECU 15 is larger than the holding duty ratio (for example, 50%), the hydraulic control valve 28 moves the spool from the neutral position to one side, and When the output duty ratio is smaller than the holding duty ratio, the spool is moved from the neutral position to the other side to open the retard chamber 31.

For this reason, when the output duty ratio (output control value) is larger than the holding duty ratio (for example, 50%), the intake camshaft 17 is advanced by the pressure of the hydraulic oil supplied to the advance chamber 30. 7, the phase angle of the intake cam 24 with respect to the exhaust cam 25 is advanced, and conversely, the output duty ratio (output control value) is greater than the holding duty ratio (for example, 50%). When it is smaller, the intake camshaft 17 is rotated to the retard side by the pressure of the working oil supplied to the retard chamber 31, and the phase angle of the intake cam 24 with respect to the exhaust cam 25 is retarded. When the output duty ratio is the holding duty ratio, the spool is moved to a neutral position that opens both the advance chamber 30 and the retard chamber 31, and both the advance chamber 30 and the retard chamber 31 are closed. As a result, the supply of the hydraulic oil to the advance chamber 30 and the retard chamber 31 is cut off, so that the intake camshaft 17 and the driven sprocket 19 are integrated, and the phase angle of the intake cam 24 is controlled to the previously controlled phase. Held in the corner.

The ECU 15 as a control means shown in FIG. 6 is an I / O (Input / Output), CPU or MP
U, a RAM, a ROM (all not shown), and a microcomputer.
Reference numeral 15 denotes a current detection circuit (not shown) for detecting an actual current value flowing through the drive coil of the hydraulic control valve 28.
And an A / D converter for A / D conversion of signals from various sensors and a shaper for waveform shaping. Also, E
The CU 15 includes a knocking sensor 32, a cam angle sensor 33 for detecting a cam angle, a crank angle sensor 34 for detecting a crank angle, a throttle opening sensor 35 for detecting a throttle opening, and for detecting a blockage of the EGR passage 8. Pressure sensor 39, a water temperature sensor 40 for detecting the temperature of the cooling water, an intake pressure sensor 41 for detecting the amount of intake air,
An O ₂ sensor (not shown) for detecting an air-fuel ratio (A / F), a lift sensor (EGR valve opening sensor) 42 for detecting a lift amount of the EGR valve 9 and the like are connected.

The cam angle sensor 33 is connected to the intake cam 2.
4, for example, a magnet sensor and an MRE pickup (magnetic pickup).
A cam pulse is output to the ECU 15 at every predetermined crank angle (for example, 180 °) with the rotation of. The crank angle sensor 34 is configured similarly to the cam angle sensor 33, and outputs a crank pulse at every predetermined crank angle (for example, 30 °) with the rotation of the crankshaft 21.
Output to U15. The crank angle sensor 34 detects a trailing tooth as a reference, and
Once every one rotation, a reference pulse is output to the ECU 15 and the water temperature sensor 40 detects the temperature of the cooling water circulating between the radiator (not shown) and the water jacket (not shown) of the engine 1. Output to ECU15. The throttle opening sensor 35 detects the throttle opening of the throttle valve 36, and the intake pressure sensor 41 detects the absolute pressure in the intake pipe and outputs it to the ECU 15.

The ECU 15 includes a crank angle sensor 34
, The phase angle of the intake cam 24 is calculated from the crank pulse output from the cam pulse sensor and the cam pulse of the cam angle sensor 33, the engine speed Ne is calculated from the crank pulse, and the intake air amount is calculated from the intake pressure. The control for improving the operation state is executed.

For example, engine speed, engine load,
The fuel injection time (fuel injection amount) of the injector 37 (see FIG. 1) is controlled based on the intake air amount, and the ignition timing is corrected based on the signal from the knocking sensor 32.
When the operation range enters the surge range based on the correction amount of the ignition timing, the hydraulic oil is supplied to the retard chamber 31 by the control of the hydraulic control valve 28 to retard the phase angle of the intake valve 6.

Then, at the time of exhaust gas recirculation, the ECU 15
From a map (not shown) optimized according to various parameters corresponding to the operating state of the engine 1, such as the load, the number of revolutions, the cooling water temperature, etc. of the engine 1, an optimal exhaust gas recirculation amount is determined for the operating state. The solenoid valve 9a is controlled so that the lift value obtained by searching a map based on the lift value of the lift sensor 42 and the recirculation amount of the exhaust gas, and the EGR is performed.
The opening degree of the valve 9 is controlled, and clogging of the EGR passage 8 and the EGR port 12 is detected by a clogging detecting means, and the VTC 27 is controlled in accordance with the clogging.

In the present embodiment, the throttle valve 3
A pressure sensor 39 provided downstream of the pressure sensor 6 and detecting the pressure in the intake pipe 4 is used as the clogging detecting means. Then, the ECU 15 opens the EGR valve 9 when the throttle valve 36 is fully closed for fuel cut, and the pressure sensor 3
The clogging state of the EGR passage 8 is determined based on the amount of change in the detection value 9.

FIG. 8 shows the EGR port 12 or the EG
9 shows a routine for determining whether the R passage 8 is clogged. As shown, first, the EGR deterioration amount, that is, the degree of clogging is calculated (S1). That is, the pressure change amount PB in the intake pipe 4 is obtained based on the pressure signal output from the pressure sensor 39. Then, the throttle valve 36 (FIG. 1)
When the fuel cut is fully closed, the EGR valve 9 is closed.
Is opened and the amount of change in the detection value of the pressure sensor 39 is determined. The smaller the amount of change, the more the EGR passage 8
When the degree of clogging is large and there is no change, the EGR
It is determined that the passage 8 is completely closed. Said E
When the clogging of the GR port 12 or the EGR passage 8 is detected, the correction map shown in FIG. 9 is searched with the pressure change amount PB, and the EGR port 12 or the EGR passage 8 is searched.
The correction request rate of the exhaust gas recirculation amount corresponding to the clogging is determined.
This correction request rate becomes the EGR deterioration amount, that is, the clogging amount. When the correction request rate is 1.0, it means that the EGR passage 8 is completely closed. As described above, when the fuel is cut, the EGR valve 9 is opened to determine the amount of change in pressure. Therefore, when determining whether the EGR passage 8 is clogged, combustion does not become unstable, and the engine emission is reduced. Does not worsen. Further, when the throttle valve 36 is fully closed, the pressure fluctuation is in a small state, so that the clogged state of the EGR passage 8 is accurately detected.

Next, based on the EGR deterioration amount, a VTC angle corresponding to the deterioration amount, that is, a correction amount VTCEGR of the phase angle of the intake cam 24 with respect to the exhaust cam 25 is calculated (STC).
2) The output duty ratio of the hydraulic control valve 28 is determined using VTCBASE + VTCEGR as the target phase angle CAINCMD (S3) of the intake cam 24 (see FIG. 10). Thereby, the phase angle of the intake cam 24 with respect to the exhaust cam 25 is advanced in accordance with the shortage of the exhaust gas recirculation amount in the EGR passage 8, and the EGR passage 8 or the EGR port 12 is changed by changing the overlap amount. The shortage of exhaust gas recirculation due to clogging is compensated.

When it is detected that the carbon adhering to the EGR passage 8 or the EGR port 12 has been separated for some reason and the clogging has been eliminated or the degree of the clogging has been reduced, the EGR deterioration amount is similarly determined. VTC angle corresponding to the amount of deterioration, ie, the correction amount VTC of the phase angle of the intake cam 24 with respect to the exhaust cam 25.
EGR is calculated (S2), and VTCBASE + VTCEG is calculated.
R to the target phase angle CAINCMD (S
As 3), the output duty ratio of the hydraulic control valve 28 is determined (see FIG. 10). Thereby, the exhaust cam 2
The phase angle of the intake cam 24 with respect to 5 is retarded in accordance with the increase in the amount of exhaust gas recirculation in the EGR passage 8, and the amount of exhaust gas recirculation is adjusted by changing the amount of overlap.

When the target phase angle CAINCMD exceeds a phase angle for improving the operating condition of the engine 1, the ECU 15 limits the phase angle by the VTC 27 to a predetermined phase angle. Prevent the condition from getting worse. That is, in such a case, the target phase angle CAIN
Without performing 100% phase angle correction on CMD,
The phase angle is corrected to 50%, and the operating state of the engine is maintained well. In this case, the predetermined phase angle is a small phase angle including 0% with respect to the target phase angle, and is a phase angle that can prevent the operating state of the engine 1 from deteriorating. During control, when the exhaust gas recirculation amount of the EGR passage 8 is restored due to some condition or when clogging is recovered by maintenance, exhaust gas recirculation (internal EGR) by the VTC 27 is prohibited, and exhaust gas by the EGR passage 8 is exhausted. Control of reflux (external EGR) is performed. Of course, at this time, the normal control of the VTC 27 is performed.

In this embodiment, the EG
Although the shortage of the recirculation amount of the exhaust gas due to the clogging of the R passage 8 is compensated for by the advance angle of the VTC 27 (phase angle adjusting means) for adjusting the phase angle of the intake cam 24 with respect to the exhaust cam 25, other explanations have been given. A variable valve timing control mechanism may be used. For example, a variable valve timing control mechanism (VTE) of a type that changes the phase angle of the exhaust valve 7 with respect to the intake valve 6 or a high-speed cam or a low-speed It is possible to apply a device that changes the phase angle of the intake cam 24 with respect to the exhaust cam 25 by the VTC 27 while switching to the cam.

In the present embodiment, the expression "adjusting the phase angle" includes both the case where the phase can be changed even with the same intake cam 24 and the case where the lift amount of the intake cam 24 is different. . Therefore, as mentioned above,
The intake cam 24 may be rotated, or the intake cam 2 may be rotated.
4, the phase angle of the exhaust cam 25 may be changed (VTE), or the phase may be changed by changing the cam peak.

Further, in the description of the embodiment, the clogging detection means detects the clogging by the pressure sensor 39. However, at least one of the downstream and the upstream of the EGR valve 9 is provided with a flow meter (FIG. (Not shown), and the state of clogging may be determined based on a change in the flow rate of exhaust gas flowing through the EGR passage 8. In that case, the accuracy of the exhaust gas recirculation amount can be improved.

A temperature sensor (not shown) for detecting the temperature of the exhaust gas or the temperature of the exhaust pipe 5 (exhaust pipe) is provided downstream of the EGR passage 8, and the amount of the recirculated exhaust gas is determined based on the temperature change. May be determined. If so, EGR
The temperature of the passage 8 can be measured from the outside.

As described above, the present invention can be variously modified, and the present invention naturally extends to the modified invention.

In summary, according to the present invention, the following excellent effects are exhibited. (1) Since the mutual phase angle between the exhaust cam and the intake cam is adjusted according to the increase or decrease of the amount of exhaust gas recirculated in the EGR passage (exhaust gas recirculation passage), it is possible to prevent deterioration of NOx. ).

(2) The mutual phase angle between the exhaust cam and the intake cam is adjusted according to the increase or decrease of the recirculation amount of the exhaust gas.
Ox can be prevented from deteriorating. When the overlap amount between the intake valve and the exhaust valve based on the exhaust gas recirculation amount in the EGR passage is larger than the overlap amount between the intake valve and the exhaust valve based on the operation state of the engine, the phase angle adjustment amount is limited by the control means. Therefore, deterioration of the operating state of the engine can be prevented (claim 2).

(3) The mutual phase angle between the exhaust cam and the intake cam is adjusted based on the clogged state of the EGR passage,
Since it is made to cope with the fluctuation of the recirculation amount of the exhaust gas by the passage, it is possible to reduce NOx (claim 3).

(4) Since clogging of the EGR passage is detected by the clogging detecting means at the time of fuel cut of the engine, clogging can be detected without deteriorating combustion of the engine such as emission.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a four-cycle engine including an EGR passage and a VTC as a phase angle adjusting means according to an embodiment of a variable valve timing engine according to the present invention.

FIG. 2 is an explanatory diagram showing a drive system and a valve train of the variable valve timing engine according to the present invention.

FIG. 3 is a detailed sectional view of a main part showing the inside of a VTC according to the present invention.

FIG. 4 shows a VTC according to the present invention, and corresponds to IV-IV in FIG.
It is a line sectional view.

FIG. 5 is an explanatory diagram showing an adjustment state of a phase angle of the intake camshaft according to the present invention.

FIG. 6 is a block diagram showing a control system and a detection system according to the present invention.

FIG. 7 is a diagram showing valve timings, phase angles, and valve lift states of intake valves and exhaust valves of the variable valve timing engine according to the present invention.

FIG. 8 is a flowchart showing the contents of exhaust gas recirculation control according to the present invention.

FIG. 9 is a diagram illustrating a correction map based on a correction request rate of an exhaust gas recirculation amount based on a pressure change amount of an EGR passage according to the present invention.

FIG. 10 shows the ratio between the amount of exhaust gas recirculation in the EGR passage and the amount of internal exhaust gas recirculation by the phase angle adjusting means during normal and degraded exhaust gas recirculation of the variable valve timing engine according to the present invention, and intake air based on the operating state of the engine. It is a figure which shows the phase angle of a cam, and the ratio of the internal exhaust gas recirculation amount by a phase angle adjustment means.

[Explanation of symbols]

 Reference Signs List 1 engine 4 intake pipe 5 exhaust pipe 6 intake valve 7 exhaust valve 8 EGR passage 9 EGR valve 15 ECU (control means) 17 intake camshaft 24 intake cam 25 exhaust cam 27 VTC (phase angle adjusting means) 39 pressure sensor (clog detection) means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02D 41/02 330 F02D 41/02 330E 41/04 320 41/04 320 41/22 320 41/22 320 43 / 00301 43/00 301N 301Z 301H 45/00 310 45/00 310Z 312 312Z F02M 25/07 510 F02M 25/07 510B 550 550L 580 580Z F term (reference) 3G018 AB04 AB17 BA33 CA20 DA66 EA22 EA23 EA26 EA31 EA31 FA09 FA23 GA08 3G062 AA10 BA09 EA12 FA19 GA02 GA04 GA06 GA15 GA21 3G084 BA13 BA20 BA23 DA10 DA22 DA27 DA28 EB22 FA00 FA10 FA11 FA13 FA20 FA25 FA37 FA38 3G092 AA11 AA17 DA01 DA10 DA12 DC09 DG05 EA01 EA01 EA01 EA01 EA01 EA04 HA11Z HA13X HD01Z HD07X HD07Z HE01Z HE08Z 3G301 HA01 HA 13 HA19 JA15 JA21 JA25 JB09 KA26 LA00 LA07 MA11 MA24 PA07Z PA11Z PC08Z PD00Z PD15Z PE00Z PE03Z PE08Z PE10Z

Claims (4)

[Claims] 1. An exhaust system for recirculating exhaust gas from an exhaust system to an intake system.
In a variable valve timing engine having a GR passage and a phase angle adjusting means for adjusting a mutual phase angle between an exhaust cam for opening and closing an exhaust valve and an intake cam for opening and closing an intake valve, the amount of exhaust gas recirculated in the EGR passage A variable valve timing engine, comprising: control means for controlling the phase angle adjusting means in accordance with the timing. 2. E for recirculating exhaust gas from an exhaust system to an intake system.
Phase angle adjusting means for adjusting the mutual phase angle of the GR passage, the exhaust cam for opening and closing the exhaust valve, and the intake cam for opening and closing the intake valve, thereby adjusting the amount of overlap in which both the intake valve and the exhaust valve are open. A variable valve timing engine having a control means for controlling the phase angle adjusting means according to a recirculation amount of the exhaust gas in the EGR passage, wherein the exhaust gas in the EGR passage is smaller than the overlap amount based on the operation state of the engine. A variable valve timing engine, wherein when the amount of overlap based on the amount of recirculation is large, the control means limits the amount of phase angle adjustment. 3. The apparatus according to claim 1, further comprising clogging detection means for detecting clogging of said EGR passage, wherein said control means controls said phase angle adjusting means based on a state of clogging of said EGR passage. The variable valve timing engine according to claim 2. 4. The variable valve timing engine according to claim 3, wherein said clogging detection means is configured to detect clogging of said EGR passage at the time of fuel cut.