JP2007071115A - Internal combustion engine having variable valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an engine from being operated under a condition inadequate for combustion by carrying out failed switching between variable control and constant control again. <P>SOLUTION: It is judged whether or not it is changed from a large-lift region of both valves to a small-lift region of one valve (step 102). When it is changed to the small-lift region of one valve, that is, when a switching pin is inserted, it is judged whether a combustion state of the engine is normal or not based on the concentration of NOx (step 106). When the combustion state is abnormal, accelerator stepping-on operation by a vehicle driver is prompted by decreasing an output of the engine (step 108). When it is changed to the small-lift region of one valve again after returning to the large-lift region of both valves by the accelerator operation, the switching pin is inserted again. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine having a variable valve mechanism, and more particularly to an internal combustion engine capable of switching a valve opening characteristic of a specific valve between variable control and constant control.

2. Description of the Related Art Conventionally, there has been known a variable valve apparatus that mechanically changes a lift amount and a working angle of a valve in accordance with an operation state of an internal combustion engine (see, for example, Patent Document 1).
According to the variable valve device of Patent Document 1, a four-bar linkage mechanism as a variable valve transmission mechanism is provided between the intake cam and the intake valve. By controlling the posture of the four-bar linkage mechanism and changing the relative position between the intake cam and the input portion of the input arm, the valve opening characteristics of the intake valve can be mechanically changed.
In the variable valve operating apparatus, a four-bar linkage mechanism (hereinafter referred to as “first link”) is provided between the first intake valve and the first intake cam and between the second intake valve and the second intake cam. Mechanism ”and“ second link mechanism ”). Further, a fixed plate that holds the posture of the second link mechanism is provided, and a pin that connects the second link mechanism and the first link mechanism or the fixed plate is provided.

When the first link mechanism and the second link mechanism are connected by this pin, the first link mechanism and the second link mechanism always take the same posture. In this case, the first intake valve and the second intake valve can be controlled to have the same valve opening characteristics.
On the other hand, when the second link mechanism and the fixing plate are connected by the pin, the posture of the second link mechanism is fixed to a constant posture. In this case, the first intake valve is controlled by controlling the attitude of the first link mechanism in a state in which the valve opening characteristic of the second intake valve is fixed to a constant valve opening characteristic (for example, a large lift amount and a large operating angle). Only the valve opening characteristics can be mechanically changed.

  That is, according to the variable valve apparatus, it is possible to selectively execute the case where the valve opening characteristics of the first and second intake valves are the same and the case where the valve opening characteristics are different. By making the valve opening characteristics (especially lift amount) different between the first intake valve and the second intake valve, it becomes possible to generate a swirl flow (swirl) in the combustion chamber, and to stabilize the combustion in the combustion chamber. It becomes possible to plan.

JP 2004-1000055 A

As described above, the variable control that can change the valve opening characteristic of the second intake valve according to the insertion position of the pin, and the constant control that the valve opening characteristic of the second intake valve is fixed to a large lift amount and a large working angle, Can be switched. In other words, the two-valve variable control and the one-valve variable control can be switched.
By the way, in order to reliably insert the pin, when switching the control of the valve opening characteristic, the position of the through hole of the first control arm, the position of the pin, and the position of the through hole of the fixing plate are completely It is desirable to match. However, it is difficult to match these positions completely because of the work accuracy. Even if they can be perfectly matched, some external force may be applied during actual switching, and the control accuracy of the rotation control shaft Etc. For this reason, it is difficult to completely match the positions of these through holes and pins.
For this reason, in any cylinder among the plurality of cylinders, a situation may occur in which the insertion of the pin into the through hole fails. If the insertion of the pin into the through hole of the fixed plate fails, the one-valve variable control cannot be performed, and the swirl is insufficient in the combustion chamber, so that an optimal combustion state cannot be obtained. As a result, the engine operation in a combustion nonconforming state is continued.

  The present invention has been made to solve the above-described problems. When switching between the variable control and the constant control fails, the failed switching is re-executed so that the engine operation in the combustion nonconforming state is performed. It aims at suppressing.

In order to achieve the above object, a first invention is an internal combustion engine having a plurality of valves on the intake side,
A variable valve mechanism that performs variable control to vary the valve opening characteristics of the specific valve among the plurality of valves;
A fixed valve mechanism that performs constant control to make only the valve opening characteristic of the specific valve constant;
Switching means for switching from variable control of the specific valve by the variable valve mechanism to constant control of the specific valve by the fixed valve mechanism according to the operating state of the internal combustion engine;
A switching failure detection means for detecting a switching failure by the switching means;
Engine switching change means is provided for reducing engine output when switching failure is detected by the switching failure detection means.

  Further, according to a second aspect, in the first aspect, the engine output changing means includes the first operating region in which constant control of the specific valve by the fixed valve mechanism is executed by an accelerator operation by a driver. The engine output is reduced until a change is made to a second operation region in which constant control of the specific valve by the variable valve mechanism is executed.

The third invention is an internal combustion engine having a plurality of valves on the intake side,
A variable valve mechanism that performs variable control to vary the valve opening characteristics of the specific valve among the plurality of valves;
A fixed valve mechanism that performs constant control to make the valve opening characteristic of the specific valve constant;
Switching means for switching from variable control of the specific valve by the variable valve mechanism to constant control of the specific valve by the fixed valve mechanism according to the operating state of the internal combustion engine;
A switching failure detection means for detecting a switching failure by the switching means;
And a switching re-execution unit that re-executes the failed switching when the switching failure detection unit detects a switching failure.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the engine output correction for correcting the engine output reduced due to the switching failure to the output based on the accelerator opening before the switching is re-executed by the switching re-execution means. Means are further provided.

  According to the first invention, when the switching from the variable control of the specific valve to the constant control fails, the vehicle driver can be urged to perform the accelerator operation by reducing the engine output. Since the operating state is temporarily changed by the accelerator operation, switching from variable control to constant control can be executed again. Therefore, it is possible to suppress engine operation in a state where constant control is not executed, that is, in a combustion nonconforming state.

  According to the second aspect of the invention, the vehicle driver can be surely operated by the accelerator to change the driving range, so that the switching can be reliably performed again by the switching means.

  According to the third aspect of the present invention, when the switching from the variable control to the constant control of the specific valve fails, the engine operation in the combustion nonconforming state can be suppressed by executing the switching again.

  According to the fourth aspect of the invention, by correcting the engine output before re-execution of switching, the driver can drive without feeling uncomfortable with the decrease in output.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System configuration]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system according to the first embodiment includes an internal combustion engine 1. The internal combustion engine 1 has a plurality of cylinders 2. FIG. 1 shows only one cylinder among a plurality of cylinders.

  The internal combustion engine 1 includes a cylinder block 4 having a piston 3 therein. The piston 3 is connected to the crankshaft 5 via a crank mechanism. A crank angle sensor 6 is provided in the vicinity of the crankshaft 5. The crank angle sensor 6 is configured to detect the rotation angle of the crankshaft 5.

  A cylinder head 8 is assembled to the upper part of the cylinder block 6. A space from the upper surface of the piston 3 to the cylinder head 8 forms a combustion chamber 10. The cylinder head 8 is provided with a spark plug 11 that ignites the air-fuel mixture in the combustion chamber 10.

  The cylinder head 8 includes an intake port 12 that communicates with the combustion chamber 10. An intake valve 14 is provided at a connection portion between the intake port 12 and the combustion chamber 10. The system according to the first embodiment is provided with a plurality of intake valves 14 corresponding to the plurality of intake ports 12. FIG. 1 shows one intake port 12 and one intake valve 14. A variable valve operating device 18 is provided between the intake valve 14 and the intake cam 16 of the intake camshaft 15. Details of the variable valve operating device 18 will be described later. The intake camshaft 15 is connected to the crankshaft 5 via a connection mechanism (not shown).

  An intake passage 19 is connected to the intake port 12. In the vicinity of the intake port 12, an injector 20 for injecting fuel is provided in the vicinity. A surge tank 21 is provided in the middle of the intake passage 19.

  A throttle valve 22 is provided upstream of the surge tank 21. The throttle valve 22 is an electronically controlled valve that is driven by a throttle motor 23. The throttle valve 22 is driven based on the accelerator opening AA detected by the accelerator opening sensor 24. A throttle opening sensor 25 is provided in the vicinity of the throttle valve 22. The throttle opening sensor 25 is configured to detect the throttle opening TA. An air flow meter 26 is provided upstream of the throttle valve 22. The air flow meter 26 is configured to detect the intake air amount Ga. An air cleaner 27 is provided upstream of the air flow meter 26.

  The cylinder head 8 includes an exhaust port 28 that communicates with the combustion chamber 10. An exhaust valve 29 is provided at the connection between the exhaust port 28 and the combustion chamber 10. An exhaust passage 30 is connected to the exhaust port 28. A catalyst 33 for purifying exhaust gas is provided in the exhaust passage 30. An air-fuel ratio sensor 31 that detects the exhaust air-fuel ratio and a NOx sensor 32 that detects the NOx concentration are provided upstream of the catalyst 33.

Further, the system of the present embodiment includes an ECU (Electronic Control Unit) 60 as a control device. In addition to the ignition plug 11, the variable valve operating device 18, the injector 20, and the throttle motor 23, the pump 82 and the discharge valve 84 (see FIG. 5), which will be described later, are connected to the output side of the ECU 60. The crank angle sensor 6, the throttle opening sensor 25, the accelerator opening sensor 24, the air flow meter 26, the air-fuel ratio sensor 31, the NOx sensor 32, and the like are connected to the input side of the ECU 60. The ECU 60 executes overall control of the internal combustion engine such as fuel injection control and ignition timing control based on the output of each sensor.
Further, the ECU 60 calculates the engine speed NE based on the output of the crank angle sensor 6.
Further, the ECU 60 calculates the engine load KL based on the accelerator opening AA detected by the accelerator opening sensor 24 and the like.
Further, the ECU 60 determines the quality of the combustion state of the internal combustion engine based on the NOx concentration detected by the NOx sensor 32.

[Configuration of variable valve gear]
FIG. 2 is a perspective view for explaining the configuration of the variable valve operating device 18 in the system shown in FIG.
As shown in FIG. 2, the intake camshaft 15 is provided with two intake cams 16 and 17 per cylinder. Two intake valves 14L and 14R are arranged symmetrically about the first intake cam 16. Between the first intake cam 16 and the intake valves 14L and 14R, variable valve mechanisms 40L and 40R are provided, respectively, which link the lift movement of the intake valves 14L and 14R with the rotational movement of the first intake cam 16. Yes. On the other hand, the second intake cam 17 is arranged so as to sandwich the second intake valve 14R between the first intake cam 16 and the second intake cam 16. A fixed valve mechanism 70 is provided between the second intake cam 17 and the second intake valve 14R to link the lift movement of the second intake valve 14R with the rotational movement of the second intake cam 17. The variable valve operating device 18 is configured to be able to selectively switch the interlocking destination of the second intake valve 14R in conjunction with the lift between the variable valve mechanism 40R and the fixed valve mechanism 70.

(1) Detailed Configuration of Variable Valve Mechanism FIG. 3 is a diagram for explaining the configuration of the variable valve mechanism 40 in the variable valve device 18 shown in FIG. Specifically, FIG. 3 is a view of the variable valve mechanism 40 as viewed from the axial direction of the intake camshaft 15. The left and right variable valve mechanisms 40L and 40R are basically symmetrical with respect to the first intake cam 16, and therefore the left and right variable valve mechanisms 40L and 40R are not distinguished here. Will be explained. In the present specification and drawings, when the left and right variable valve mechanisms 40L and 40R are not distinguished, they are simply referred to as the variable valve mechanism 40. Similarly, the component parts of the variable valve mechanisms 40L, 40R and the symmetrically arranged parts such as the intake valves 14L, 14R are distinguished from each other except when it is necessary to distinguish between them. The symbol is not attached.

  As shown in FIG. 3, the rocker arm 35 is supported by the intake valve 14. The variable valve mechanism 40 is interposed between the first intake cam 16 and the rocker arm 35. The variable valve mechanism 40 is configured to continuously change the interlocking state between the rotational motion of the first intake cam 16 and the rocking motion of the rocker arm 35.

  The variable valve mechanism 40 has a control shaft 41 disposed in parallel with the intake camshaft 15. A control arm 42 is fixed to the control shaft 41 with bolts 43. A part of the control arm 42 protrudes in the radial direction of the control shaft 41. An intermediate arm 44 is attached to the protruding portion of the control arm 42 by a pin 45. The pin 45 is disposed at a position eccentric from the center of the control shaft 41. Therefore, the intermediate arm 44 is configured to swing around the pin 45.

  A swing cam arm 50 is swingably supported on the control shaft 41. The swing cam arm 50 has a slide surface 50 a on the side facing the first intake cam 16. The slide surface 50 a is formed so as to contact the second roller 53. The slide surface 50a is formed in a curved surface such that the distance from the first intake cam 16 gradually decreases as the second roller 53 moves from the distal end side of the swing cam arm 50 toward the axial center side of the control shaft 41. ing. Further, the swing cam arm 50 has a swing cam surface 51 on the opposite side of the slide surface 50a. The rocking cam surface 51 has a non-acting surface 51a formed so that the distance from the rocking center of the rocking cam arm 50 is constant, and the position away from the non-working surface 51a is closer to the axis of the control shaft 41. It is comprised with the action surface 51b formed so that distance may become far.

  A first roller 52 and a second roller 53 are disposed between the slide surface 50 a and the peripheral surface of the first intake cam 16. More specifically, the first roller 52 is disposed so as to contact the peripheral surface of the first intake cam 16. The second roller 53 is disposed so as to contact the slide surface 50 a of the swing cam arm 50. Both the first roller 52 and the second roller 53 are rotatably supported by a connecting shaft 54 fixed to the tip of the intermediate arm 44. Since the intermediate arm 44 swings around the pin 45 as a fulcrum, the rollers 52 and 53 also swing along the slide surface 50 a and the peripheral surface of the first intake cam 16 while maintaining a certain distance from the pin 45.

  The swing cam arm 50 is formed with a spring seat 50b. One end of a lost motion spring 38 is hung on the spring seat 50b. The other end of the lost motion spring 38 is fixed to a stationary part of the internal combustion engine. The lost motion spring 38 is a compression spring. Due to the biasing force received from the lost motion spring 38, the slide surface 50 a of the swing cam arm 50 is pressed against the second roller 53, and further, the first roller 52 is pressed against the first intake cam 16. As a result, the first roller 52 and the second roller 53 are positioned in a state of being sandwiched between the slide surface 50a and the peripheral surface of the first intake cam 16 from both sides.

  The rocker arm 35 is disposed below the swing cam arm 50. A rocker roller 36 is provided on the rocker arm 35 so as to face the swing cam surface 51. The rocker roller 36 is rotatably attached to an intermediate portion of the rocker arm 35. One end of the rocker arm 35 is supported by a valve shaft 14 a of the valve 14, and the other end of the rocker arm 35 is rotatably supported by a hydraulic lash adjuster 37. During the lift operation, the valve shaft 14a is urged in a closing direction, that is, a direction in which the rocker arm 35 is pushed up by a valve spring (not shown). The rocker roller 36 is pressed against the swing cam surface 51 of the swing cam arm 50 by the biasing force and the hydraulic lash adjuster 37.

  According to the configuration of the variable valve mechanism 40 described above, the pressing force of the first intake cam 16 is transmitted to the slide surface 50 a via the first roller 52 and the second roller 53 as the first intake cam 16 rotates. Is done. As a result, when the contact point between the swing cam surface 51 and the rocker roller 56 extends from the non-operation surface 51a to the operation surface 51b, the rocker arm 35 is pushed down and the valve 14 is opened.

  Further, according to the configuration of the variable valve mechanism 40, when the rotation angle of the control shaft 41 is changed, the position of the second roller 53 on the slide surface 50a changes, and the swing cam arm 50 swings during the lift operation. The range changes. More specifically, when the control shaft 41 is rotated in the counterclockwise direction in FIG. 3, the position of the second roller 53 on the slide surface 50 a moves to the tip side of the swing cam arm 50. Then, the rotation angle of the swing cam arm 50 that is actually required until the rocker arm 35 starts to be pressed after the swing cam arm 50 starts swinging by transmitting the pressing force of the first intake cam 16 is: The control shaft 41 becomes larger as it rotates counterclockwise in FIG. That is, the operating angle and lift amount of the valve 14 can be reduced by rotating the control shaft 41 counterclockwise in FIG. Conversely, the operating angle and lift amount of the valve 14 can be increased by rotating the control shaft 41 in the clockwise direction.

(2) Detailed Configuration of Fixed Valve Mechanism Next, a detailed configuration of the fixed valve mechanism 70 will be described with reference to FIGS. 2 and 4. FIG. 4 is an exploded perspective view showing the variable valve mechanism 40 and the fixed valve mechanism 70 shown in FIG.
As shown in FIG. 2, the fixed valve mechanism 70 is interposed between the second intake cam 17 and the second swing cam arm 50R. The fixed valve mechanism 70 interlocks the swing motion of the second swing cam arm 50 </ b> R with the rotational motion of the second intake cam 17. The fixed valve mechanism 70 includes a large lift arm 71 driven by the second intake cam 17 and an arm coupling mechanism 72 (see FIG. 4) for coupling the large lift arm 71 to the second swing cam arm 50R. . The arm coupling mechanism 72 includes a switching pin 74, a hydraulic chamber 75, a pin hole 76, a return spring 77, and a piston 78, which will be described later.

The large lift arm 71 is arranged on the control shaft 41 side by side with the second swing cam arm 50R, and is rotatable independently of the second swing cam arm 50R. An input roller 73 that contacts the peripheral surface of the second intake cam 17 is rotatably supported on the large lift arm 71.
As shown in FIG. 4, a spring seat 71 a is formed on the large lift arm 71. As with the swing cam arm 50, a lost motion spring (not shown) is hung on the spring seat 71a. The input roller 73 is pressed against the peripheral surface of the second intake cam 17 by the spring force of the lost motion spring.

  The large lift arm 71 includes a switching pin 74 that can be taken in and out toward the second swing cam arm 50R. The large lift arm 71 is formed with a hydraulic chamber 75 having an opening on the second swing cam arm 50R side. A switching pin 74 is fitted in the hydraulic chamber 75. The hydraulic chamber 75 is connected to a hydraulic system described later. When the hydraulic pressure in the hydraulic chamber 75 is increased by the hydraulic system, the switching pin 74 is pushed out from the hydraulic chamber 75 toward the second swing cam arm 50R by the hydraulic pressure.

  On the other hand, a pin hole 76 having an opening on the large lift arm 71 side is formed in the second swing cam arm 50R. The switching pin 74 and the pin hole 76 are arranged on the same arc centered on the control shaft 41. Accordingly, when the second swing cam arm 50R is positioned at a predetermined rotation angle with respect to the large lift arm 71, the position of the pin hole 76 and the position of the switching pin 74 are made to coincide. A return spring 77 and a piston 78 as a lifter are disposed in the pin hole 76 from the back side.

FIG. 5 is a schematic diagram showing a configuration of a hydraulic system for operating the switching pin 74.
As shown in FIG. 5, an oil passage 81 is formed in the control shaft 41. The oil passage 81 is connected to the hydraulic chamber 75, the sliding gap between the control shaft 41 and the large lift arm 71, and the sliding gap between the control shaft 41 and the second swing cam arm 50R. The oil passage 81 is connected to a pump 82. A discharge path 83 is connected in the middle of the oil path 81. A discharge valve 84 is provided in the discharge path 83. Further, an orifice 85 is provided downstream of the discharge valve 84 in the discharge path 83.
The lubricating oil pressurized by the pump 82 is supplied to the sliding gap through the oil passage 81. A part of the lubricating oil flowing through the oil passage 81 is supplied to the hydraulic chamber 75. Therefore, the hydraulic pressure in the hydraulic chamber 85 can be increased. On the other hand, when the discharge valve 84 is opened, the lubricating oil is discharged from the discharge path 83. Thereby, the hydraulic pressure in the hydraulic chamber 85 can be lowered. The switching pin 74 can be operated by controlling the hydraulic pressure in the hydraulic chamber 75.

[Features of Embodiment 1]
(Single valve variable control)
In the above system, when the second swing cam arm 50R is positioned at a predetermined rotation angle with respect to the large lift arm 71, the positions of the switching pin 74 and the pin hole 76 coincide. When the position of the pin hole 76 coincides with the position of the switching pin 74, the switching pin 74 contacts the piston 78. At this time, if the hydraulic pressure in the hydraulic chamber 75 is larger than the force that pushes the switching pin 74 than the force that the return spring 77 pushes the piston 78, the switching pin 74 pushes the piston 78 into the back of the pin hole 76. Then, it enters the pin hole 76. That is, the switching pin 74 can be inserted into the pin hole 76 by increasing the hydraulic pressure in the hydraulic chamber 75 by the hydraulic system. When the switching pin 74 is inserted into the pin hole 76, the second swing cam arm 50R and the large lift arm 71 are connected. Thereby, the interlocking destination of the lift movement of the second intake valve 14R can be switched from the variable valve mechanism 20R to the fixed valve mechanism 70.
In this case, the rotational motion of the intake camshaft 15 is transmitted from the second intake cam 14 via the large lift arm 71 to the second swing cam arm 50R. The valve opening characteristics of the second intake valve 14R are mechanically determined by the shapes and positional relationships of the second intake cam 17, the large lift arm 71, and the second swing cam arm 50R, and are always constant regardless of the rotation angle of the control shaft 41. The valve opening characteristics (large lift and large working angle) are fixed. That is, constant control is performed to make the valve opening characteristic of the second intake valve 14R constant. On the other hand, the rotational motion of the intake camshaft 15 is transmitted from the first intake cam 16 to the first swing cam arm 50L via the first roller 52 and the second roller 53L. Therefore, the valve opening characteristic of the first intake valve 14L changes in conjunction with the rotation angle of the control shaft 41.
Therefore, one-valve variable control is performed in which only the valve opening characteristic of the first intake valve 14L can be changed in conjunction with the rotation angle of the control shaft 41 while the valve opening characteristic of the second intake valve 14R is fixed. Can do.

(Double valve variable control)
On the other hand, when the position of the pin hole 76 coincides with the position of the switching pin 74, the switching pin 74 can be removed from the pin hole 76 by lowering the hydraulic pressure in the hydraulic chamber 75 by the hydraulic system. Thereby, the connection between the large lift arm 71 and the second swing cam arm 50R is released. Therefore, the interlocking destination of the lift movement of the second intake valve 14R can be switched from the fixed valve mechanism 70 to the variable valve mechanism 20R.
In this case, the rotational motion of the cam shaft 15 is transmitted from the first intake cam 16 to the slide surfaces 50a of the first and second swing cam arms 50L, 50R via the first and second rollers 52, 53. The Therefore, the valve opening characteristics of the first intake valve 14L and the second intake valve 14R are the same and change in conjunction with the rotation of the control shaft 41. That is, variable control is performed to vary the valve opening characteristic of the second intake valve 14R.
Therefore, the variable valve control can be performed in which the valve opening characteristic of the first intake valve 14L and the valve opening characteristic of the second intake valve 14R can be changed together in conjunction with the rotation angle of the control shaft 41.

FIG. 6 is a diagram showing the relationship between the operation region and the valve opening characteristic control of the intake valve.
As shown in FIG. 6, the valve opening characteristic control region of the intake valve is determined by an operation region determined by the engine speed NE and the load KL.
In the double-valve variable control region (hereinafter, also referred to as “double-valve large lift region”) in which the double-valve variable control is performed, priority is given to obtaining a large amount of intake air, so the demand for swirl is low. In this region, since the switching pin 74 is housed in the large lift arm 71, the second intake valve 14R is variably controlled. Therefore, by controlling the rotation angle of the control shaft 41 by the ECU 60 during engine operation, the valve opening characteristics of both the intake valves 14L and 14R are both set to a large lift and a large operating angle.
On the other hand, in the single valve variable control region (hereinafter also referred to as “single valve small lift region”), the demand for swirl is high. In this region, a part of the switching pin 74 exits from the large lift arm 71 and is inserted into the second swing cam arm 50R, so that the second intake valve 14R is constantly controlled. Therefore, during engine operation, the valve opening characteristic of the second intake valve 14R is fixed to a large lift and a large operating angle, and the valve opening characteristic of the first intake valve 14L is continuously varied.
The boundary between the double valve variable control region (double valve large lift region) and the single valve variable control region (single valve small lift region) is the switching pin operation line A.

  For example, assume that the vehicle is operating at point B shown in FIG. Since the point B is a both-valve variable control region, the switching pin 74 is accommodated in the hydraulic chamber 75 of the large lift arm 71. Thereafter, when the accelerator opening is reduced by the vehicle driver, the driving state moves along the torque curve C as indicated by an arrow E. The switching pin 74 is inserted into the pin hole 76 of the second swing cam arm 50R at the intersection D between the torque curve C and the switching pin operation line A. Thereby, the large lift arm 71 and the second swing cam arm 50R are connected. As a result, the second intake valve 14R is controlled so that the valve opening characteristic is fixed.

  However, at a point D on the switching pin operation line A, the switching pin 74 is inserted in a plurality of cylinders. There may occur a situation in which the insertion of the switching pin 74 fails in any cylinder. In this case, since the required swirl cannot be generated in the combustion chamber, the operation is continued in a combustion incompatible state. If the swirl is insufficient, unburned HC increases and torque decreases. If the fuel injection amount is increased in order to compensate for this torque reduction, the fuel efficiency will deteriorate.

Therefore, in the first embodiment, when it is determined that the insertion of the switching pin has failed, the engine output is forcibly reduced by a certain rate. This prompts the vehicle driver to depress the accelerator pedal. When the accelerator pedal is depressed by the vehicle driver, as indicated by an arrow F, the operation area returns from the single valve small lift area to the double valve large lift area. That is, the switching pin 74 is pulled out from the second swing cam arm 50R. Here, since the accelerator pedal is excessively depressed by the vehicle driver, the vehicle driver returns the accelerator pedal. As a result, the switching pin operation line is crossed again, and the insertion of the switching pin into the second swing cam arm 50R is executed again.
Therefore, when the insertion of the switching pin fails, the engine output is reduced to prompt the driver to depress the accelerator. By temporarily returning to the double valve large lift region by depressing the accelerator, the switching pin can be pulled out, and then the switching pin 74 can be inserted again. Thereby, engine operation in a combustion nonconformity state can be controlled. As a result, the deterioration of emissions can be suppressed, and the deterioration of driving performance (drivability) can be suppressed. Further, deterioration of the valve system, combustion chamber peripheral components, lubricating oil, internal combustion engine cooling water, and the like can be prevented, so that the durability of the internal combustion engine can be improved.

[Specific Processing in Embodiment 1]
FIG. 7 is a flowchart showing a routine executed by the ECU 60 in the first embodiment.
According to the routine shown in FIG. 7, first, it is determined whether or not the operation region is a double valve large lift region (step 100). Here, the ECU 60 can grasp the operating range from the engine speed NE and the load KL.

  When it is determined in step 100 that the operation region is the double valve large lift region, the process of step 102 is executed. In step 102, it is determined whether or not the operation area has changed to a single valve small lift area. In this step 102, it is determined whether or not the switching pin operation line A shown in FIG. 6 is straddled in the direction from high rotation to low rotation, that is, whether or not the insertion of the switching pin 74 into the second swing cam arm 50R has been executed. Determined.

  If it is determined in step 102 that the operation region has changed to the one-valve small lift region, that is, if it is determined that the switching pin 74 has been inserted into the second swing cam arm 50R, the internal combustion engine 1 A combustion state is detected (step 104). In step 104, the ECU 60 reads the NOx concentration from the NOx sensor 32.

  Next, it is determined whether or not the combustion state is normal based on the NOx concentration read in step 104 (step 106). In step 106, the ECU 60 refers to a map stored in advance in the ECU 60 and reads the allowable range of the NOx concentration according to the engine speed NE and the load KL. Then, it is determined whether or not the NOx concentration read in step 104 is within the allowable range, that is, the NOx concentration range in the normal combustion state.

  If it is determined in step 106 that the combustion state is abnormal, it is determined that the insertion of the switching pin 74 has failed in at least one of the cylinders. Here, if the operation is performed while the insertion of the switching pin 74 has failed, the optimum combustion state cannot be obtained due to insufficient swirl. As a result, the NOx concentration is usually lower than in the optimum combustion state (that is, the allowable range). Further, when the temperature is partially increased in the combustion chamber 10, the temperature becomes higher than the allowable range. As described above, when the NOx concentration is out of the allowable range and it is determined that the combustion state is abnormal, the engine output is decreased by a certain percentage (step 108). The ECU 60 can select at least one of a method of retarding the ignition timing, a method of reducing the air amount by closing the throttle valve, and a method of reducing the fuel injection amount as a method of reducing the engine output. Thus, by depressing the engine output, the vehicle driver is prompted to depress the accelerator pedal. The reduction rate can be determined according to the vehicle type and engine characteristics.

Next, it is determined whether or not the operating area has returned to the double valve large lift area (step 110). In this step 110, it is determined whether or not the switching pin operation line shown in FIG. 6 is straddled in the direction from low rotation to high rotation as a result of the accelerator pedal being depressed by the vehicle driver.
If it is determined in step 110 that the valve has not returned to the double valve large lift region, the process returns to step 108. As a result, the engine output is further reduced by a certain percentage.

  If it is determined in step 110 that the valve has returned to the double valve large lift region, the process returns to step 102. Returning to the process of step 102 in this way is a state in which the vehicle driver is depressing the accelerator excessively. Therefore, the vehicle driver usually returns the accelerator. As a result, the operation area once returns to the double-valve large lift area and then moves to the single-valve small lift area. Therefore, the insertion of the switching pin 74 is executed again. If it does so, it will determine with "YES" at step 102, and the process of step 104,106 will be performed. That is, in the same manner as described above, based on the NOx concentration taken from the NOx sensor 32, it is determined whether or not the combustion state is normal. When it is determined that the combustion state is normal, it is determined that the switching pins 74 have been normally inserted in all the cylinders 2, and this routine is terminated. On the other hand, when it is determined that the combustion state is abnormal, it is determined that the insertion of the switching pin 74 has failed in at least one of the cylinders, and the process of step 108 is performed again as described above.

  As described above, according to the routine shown in FIG. 7, after the operating region is changed from the double valve large lift region to the single valve small lift region, that is, the switching pin 74 is inserted into the second swing cam arm 50R. After the execution, it is determined whether or not the combustion state is normal based on the NOx concentration. If it is determined that the combustion state is abnormal, that is, if there is a failure to insert the switching pin 74 in any cylinder, the engine output is decreased and the vehicle driver is prompted to depress the accelerator. . When the vehicle driver depresses the accelerator, the operating area is returned to the double-valve large lift area, and the accelerator is returned to the single-valve small lift area so that the switching pin 74 is inserted into the second swing cam arm 50R again. Can be executed. Therefore, it is possible to suppress the operation from being continued in a state where the insertion of the switching pin 74 has failed, that is, in a combustion nonconforming state.

  In the first embodiment, the quality of the combustion state is determined based on the NOx concentration. However, an HC sensor is provided in place of the NOx sensor 32, and it is determined whether the combustion state is normal based on the HC concentration. May be. Further, an exhaust temperature sensor or an in-cylinder pressure sensor may be provided to determine whether or not the combustion state is normal based on the exhaust temperature or the in-cylinder pressure sensor. In these cases, the same effect as in the first embodiment can be obtained.

In the first embodiment, the switching pin 74 is provided in the large lift arm 71 and the pin hole 76 is provided in the second swing cam arm 50R. However, the pin hole is provided in the large lift arm and the switching pin is the second. You may provide in rocking cam arm 50R.
Further, although hydraulic pressure is used as the driving force for operating the switching pin 74, other driving force such as electromagnetic force may be used.

  Moreover, although the gasoline engine was demonstrated in this Embodiment 1, this invention is applicable also to a diesel engine. In this case, as a method of reducing the engine output, a method of retarding the injection timing and / or a method of reducing the fuel injection amount can be selected.

  In the first embodiment, when the ECU 60 executes the process of step 106, the “switching failure detecting means” in the first invention executes the process of step 108, and “ The “engine output changing means” in the second aspect of the present invention is realized by executing the processing of step 110.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. The system of the second embodiment can be realized by causing the ECU 60 to execute a routine shown in FIG. 8 described later using the hardware configuration shown in FIGS.

[Features of Embodiment 2]
In the first embodiment, it is determined whether or not the switching pin has been normally inserted based on the NOx concentration. If it is determined that the switching pin has not been inserted successfully, the engine output is forcibly reduced. And urged the driver to depress the accelerator pedal. Then, by depressing the accelerator, the operating region is temporarily returned to the double-valve large lift region, and the switching pin can be inserted again when changing to the single-valve small lift region.
However, since the engine output is reduced by a certain percentage in order to cause the driver to depress the accelerator pedal, the driver may feel uncomfortable during driving.

  Therefore, in the second embodiment, as in the first embodiment, it is determined whether or not the insertion of the switching pin has been executed normally. If it is determined that the insertion of the switching pin has failed, the engine output is opened. Request output from degrees. That is, the correction of the engine output reduced due to the failure to insert the switching pin is executed. Then, regardless of the operation region, the switching pin 74 is once pulled out and inserted again. Therefore, the switching pin can be retried without causing the driver to feel uncomfortable.

[Specific Processing in Second Embodiment]
FIG. 7 is a flowchart showing a routine executed by ECU 60 in the second embodiment.
In the routine shown in FIG. 7, steps 112 and 114 are added in place of steps 108 and 110 in the flowchart of the first embodiment.

  That is, according to this routine, the determination process of step 106 is executed as in the first embodiment. If it is determined in step 106 that the combustion state is abnormal, it is determined that the insertion of the switching pin 74 has failed in at least one of the cylinders. In this case, since the constant control of the second intake valve 14R cannot be performed in the cylinder in which the insertion of the switching pin 74 has failed, the one-valve small lift operation cannot be performed. As a result, the swirl is insufficient with respect to the required swirl, and an optimal combustion state cannot be obtained. For this reason, the actual engine output becomes lower than the required output from the accelerator opening. In step 112, the engine output is increased so as to obtain the required output from the accelerator opening. Here, as a method for correcting the output increase, the ECU 60 is at least one of a method of advancing the ignition timing, a method of increasing the combustion injection amount, and a method of increasing the air amount by increasing the throttle opening TA. One can be selected. In this way, by increasing the engine output, the vehicle driver can travel without feeling uncomfortable due to insufficient output even when there is a mistake in inserting the switching pin 74.

  Then, after the switching pin 74 is once removed from the second swing cam arm 50R to be within the hydraulic chamber 75 of the large working angle arm 71, the switch pin 74 is inserted into the second swing cam arm 50R. Execute (step 114). That is, after forcibly setting the double valve large lift state once, the insertion of the switching pin 74 is retried to set the single valve small lift state.

  As described above, according to the routine shown in FIG. 8, when it is determined that the combustion state is abnormal, that is, when there is an insertion error of the switching pin 74 in any cylinder, the insertion error is determined. The accompanying decrease in engine output is corrected, and the switching pin 74 is forcibly removed and inserted again. Therefore, the insertion of the switching pin can be executed again without making the driver feel uncomfortable.

  In the second embodiment, the ECU 60 executes the process of step 106, so that the “switching failure detecting means” in the third invention executes the process of step 114, thereby executing the “switching in the third invention”. The “re-execution means” executes the processing of step 112, thereby realizing the “engine output correction means” in the fourth invention.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. FIG. 2 is a perspective view for explaining the configuration of a variable valve operating device 18 in the system shown in FIG. 1. It is a figure for demonstrating the structure of the variable valve mechanism in the variable valve apparatus shown in FIG. FIG. 3 is an exploded perspective view showing a variable valve mechanism 40 and a fixed valve mechanism 70 shown in FIG. 2. FIG. 3 is a schematic diagram showing a configuration of a hydraulic system for operating a switching pin 74. It is a figure which shows the relationship between an operation area | region and the valve opening characteristic control of an intake valve. 5 is a flowchart showing a routine that is executed by the ECU 60 in the first embodiment of the present invention. In Embodiment 2 of this invention, it is a flowchart which shows the routine which ECU60 performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Piston 4 Cylinder block 5 Crankshaft 6 Crank angle sensor 8 Cylinder head 10 Combustion chamber 11 Spark plug 12 Intake port 14 Intake valve 15 Intake camshaft 16, 17 Intake cam 18 Variable valve apparatus 19 Intake passage 20 Injector 21 Surge tank 22 Throttle valve 23 Throttle motor 24 Accelerator opening sensor 25 Throttle opening sensor 26 Air flow meter 27 Air cleaner 28 Exhaust port 30 Exhaust passage 31 Air-fuel ratio sensor 32 NOx sensor 33 Catalyst 35 Rocker arm 36 Rocker roller 37 Hydraulic lash Adjuster 38 Lost motion spring 40 Variable valve mechanism 41 Control shaft 42 Control arm 43 Bolt 44 Intermediate arm 45 Pin 50 Oscillating cam arm 52 First roller 53 Second roller 54 Connecting shaft 60 ECU
70 fixed valve mechanism 71 large lift arm 72 arm coupling mechanism 73 input roller 74 switching pin 75 hydraulic chamber 76 pin hole 77 return spring 78 piston 81 oil passage 82 pump 83 discharge passage 84 discharge valve 85 orifice

Claims (4)

An internal combustion engine having a plurality of valves on the intake side,
A variable valve mechanism that performs variable control to vary the valve opening characteristics of the specific valve among the plurality of valves;
A fixed valve mechanism that performs constant control to make only the valve opening characteristic of the specific valve constant;
Switching means for switching from variable control of the specific valve by the variable valve mechanism to constant control of the specific valve by the fixed valve mechanism according to the operating state of the internal combustion engine;
A switching failure detection means for detecting a switching failure by the switching means;
An internal combustion engine having a variable valve mechanism, comprising: engine output changing means for reducing engine output when a switching failure is detected by the switching failure detecting means. An internal combustion engine having the variable valve mechanism according to claim 1,
The engine output changing means is configured to execute constant control of the specific valve by the variable valve mechanism from a first operating region in which constant control of the specific valve by the fixed valve mechanism is executed by an accelerator operation by a driver. An internal combustion engine having a variable valve mechanism that reduces the engine output until the second operating range is reached. An internal combustion engine having a plurality of valves on the intake side,
A variable valve mechanism that performs variable control to vary the valve opening characteristics of the specific valve among the plurality of valves;
A fixed valve mechanism that performs constant control to make the valve opening characteristic of the specific valve constant;
Switching means for switching from variable control of the specific valve by the variable valve mechanism to constant control of the specific valve by the fixed valve mechanism according to the operating state of the internal combustion engine;
A switching failure detection means for detecting a switching failure by the switching means;
An internal combustion engine having a variable valve mechanism, comprising: a switching re-execution unit that re-executes a failed switching when a switching failure is detected by the switching failure detection unit. In the internal combustion engine having the variable valve mechanism according to claim 3,
The variable valve mechanism further comprising an engine output correcting means for correcting the engine output reduced due to the switching failure to an output based on the accelerator opening before re-execution of switching by the switching re-execution means. An internal combustion engine.

Images