JP4792952B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for a multi-cylinder internal combustion engine, and more particularly, to a control device applied to an internal combustion engine provided with a variable valve mechanism that varies a valve characteristic of an engine valve provided in each cylinder.

  Valve timing (open / close timing), valve lift amount, working angle (valve opening period) for the purpose of increasing the output of internal combustion engines (hereinafter also referred to as engines) mounted on automobiles, improving fuel efficiency, and improving exhaust emissions. 2. Description of the Related Art A variable valve mechanism that varies the valve characteristics of engine valves (intake valves / exhaust valves) is known.

  As an example of a variable valve mechanism, a cylindrical rocker shaft fixed to an internal combustion engine, a control shaft disposed in an axially movable state within the rocker shaft, and an engine provided on the rocker shaft A mechanism including a variable valve lift mechanism that continuously changes the valve operating angle and the valve lift amount has been proposed (see, for example, Patent Document 1).

  In a multi-cylinder internal combustion engine equipped with this type of variable valve mechanism, there is a method for detecting variations in intake air amount between cylinders as a technique for detecting variations between cylinders (see, for example, Patent Document 2).

In the method described in Patent Document 2, (1) combustion is not generated in the cylinder at the time of fuel cut or cranking, and it is not affected by the rotational fluctuation due to combustion. The detection accuracy is improved by detecting variations in the intake air amount between cylinders using the ranking execution condition as a detection execution condition. (2) In consideration of the fact that the lift is low during the deceleration operation and the variation in the actual lift with respect to the target lift becomes large, the detection accuracy is improved by detecting the intake air amount variation between the cylinders during the deceleration operation. (3) Taking advantage of the fact that as the engine speed decreases, the time for one cycle becomes longer and the number of samplings for detecting variations can be increased, suction between cylinders is performed when the engine speed is equal to or lower than a predetermined speed. The detection accuracy is improved by detecting the variation in the air amount.
JP 2001-263015 A JP 2004-190593 A

  By the way, in a multi-cylinder internal combustion engine equipped with the above-described variable valve mechanism, the working angle between cylinders may vary due to factors such as dimensional tolerance and assembly tolerance of the variable valve mechanism and thermal expansion (axial expansion) of the control shaft. May vary. If there is a variation in operating angle between cylinders, the operating state of the internal combustion engine becomes unstable in idling or partial areas, which affects output characteristics such as torque characteristics and exhaust gas characteristics. It is necessary to detect and correct the variable valve mechanism.

  As a condition for detecting the variation in the operating angle between the cylinders, an idling operation in which the operation state is stable can be cited. However, in the operation region such as the idling region, that is, the operation region where the engine speed, the load, the boost pressure pm, and the like are small, the difference in the intake air amount between the cylinders is small, and the variation in the working angle between the cylinders can be accurately detected. Can not.

  The present invention has been made in view of such circumstances, and in a multi-cylinder internal combustion engine having a variable valve mechanism that makes the working angle of an engine valve variable, it is possible to accurately detect variation in working angle between cylinders. An object of the present invention is to provide a control device for an internal combustion engine capable of stabilizing the combustion state of the internal combustion engine.

  In the present invention, as shown in FIG. 14, when the engine speed (engine speed) increases, the boost pressure pm increases, and the difference in A / F between cylinders, that is, the variation in intake air amount increases. The feature is that the detection of the variation in the working angle is improved by increasing the difference in the intake air amount between the cylinders by increasing the engine speed only when detecting the variation in the working angle between the cylinders. .

-Solution-
Specifically, the present invention is a control device applied to an internal combustion engine having a variable valve mechanism that varies the operating angle of an engine valve provided in each of a plurality of cylinders. Detection means for detecting variation in operating angle, and control means for executing control for increasing the engine speed by changing the operating state of the internal combustion engine when detecting variation in operating angle between the cylinders. It is characterized by that.

  By this specific matter, even if the operating angle variation is small, such as during idling, the operating angle variation can be increased by increasing the engine speed only when detecting the operating angle variation between cylinders. Therefore, it is possible to accurately detect the variation in the working angle between the cylinders. Then, by correcting the variable valve mechanism based on the detection result thus obtained, it is possible to stabilize the combustion state of the internal combustion engine in an idling or partial region.

  In the present invention, a crank position sensor for detecting the crank angle of the crankshaft of the internal combustion engine is used as a specific means for detecting the operating angle variation between the cylinders, and the variation amount of the crank angular speed obtained from the output of the crank position sensor. The method of detecting the working angle variation between cylinders based on the above can be mentioned. The timing for detecting the operating angle variation between the cylinders is, for example, the timing of detecting the operating angle variation by increasing the engine speed when the engine reaches a fully warm-up state after the engine is started. be able to.

  According to the present invention, in a multi-cylinder internal combustion engine having a variable valve mechanism that varies the operating angle of an engine valve provided in each of a plurality of cylinders, Since the engine speed is increased by changing the engine operating state, it is possible to accurately detect the operating angle variation between the cylinders and to stabilize the combustion state of the internal combustion engine in the idling and partial regions. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An engine (internal combustion engine), a variable valve mechanism and an ECU to which the present invention is applied will be described with reference to FIGS.

-Engine-
The engine 1 of this example is an in-line four-cylinder gasoline engine mounted on a vehicle, and includes a cylinder head 11 and a cylinder block 13 having four cylinders (cylinders: # 1 to # 4) 12. In each cylinder 12 (# 1 to # 4), a piston 1a is accommodated in a reciprocable manner. The piston 1a is connected to the crankshaft 10 via a connecting rod, and the reciprocating motion of the piston 1a is converted into rotation of the crankshaft 10 by the connecting rod.

  The cylinder head 11 of the engine 1 is provided with a pair of intake ports 15 and exhaust ports 16 communicating with the respective combustion chambers 1 b for each cylinder 12. Further, a spark plug 3 is arranged for each cylinder 12 in the combustion chamber 1 b of the engine 1.

  The cylinder head 11 is provided with an intake valve 21 for opening and closing each intake port 15 and an exhaust valve 22 for opening and closing the exhaust port 16. Each intake valve 21 is provided with a valve spring 25, and each intake valve 21 is biased in a direction to close the intake port 15 by the elastic force of the valve spring 25. Similarly, each exhaust valve 22 is provided with a valve spring 25.

  Above the intake valve 21, an intake camshaft 23 having one intake cam 23a for each cylinder 12 (# 1 to # 4) is disposed. The intake camshaft 23 is rotatably supported by a plurality of support walls 17. Further, an exhaust camshaft 24 having one exhaust cam 24 a for each cylinder 12 is disposed above the exhaust valve 22. The exhaust camshaft 24 is rotatably supported by a plurality of support walls 18. The intake camshaft 23 and the exhaust camshaft 24 are drivingly connected to the crankshaft 10 via the timing chain 14 and the like. The rotation of the crankshaft 10 is transmitted to the intake camshaft 23 and the exhaust camshaft 24 via the timing chain 14 and the like, and the intake valve 21 and the exhaust valve 22 are rotated by the rotation of the intake camshaft 23 and the exhaust camshaft 24. Each reciprocates.

  A rocker arm 26 having a roller 26a is swingably disposed between the upper end portion of the intake valve 21 and the intake cam 23a and between the upper end portion of the exhaust valve 22 and the exhaust cam 24a. Further, hydraulic lash adjusters 27 are disposed in the vicinity of the upper ends of the intake valve 21 and the exhaust valve 22, respectively. A compression reaction force of the valve spring 25 and a push-up force of the lash adjuster 27 are transmitted to the rocker arm 26, and the roller 26a of the rocker arm 26 is biased substantially upward by these transmission forces. The roller 26a having such a structure directly contacts the exhaust cam 24a and indirectly contacts the intake cam 23a via a variable valve mechanism 30 described later.

  In the engine 1 described above, an intake passage is connected to the intake port 15, and air outside the engine 1 is taken into the combustion chamber 1 b through the intake passage and the intake port 15. An injector 2 for fuel injection is disposed in the intake passage. Fuel of a predetermined pressure is supplied from the fuel tank to the injector 2 by a fuel pump, and the fuel is injected into the intake passage. This injected fuel is mixed with intake air to form an air-fuel mixture, and is introduced into the combustion chamber 1 b of the engine 1 through each intake port 15. The air-fuel mixture (fuel + air) introduced into the combustion chamber 1b is ignited by the spark plug 3 and combusted and exploded. The piston 1a reciprocates due to combustion / explosion of the air-fuel mixture in the combustion chamber 1b, and the crankshaft 10 rotates. The engine 1 burns and explodes in the order of the first cylinder # 1, the third cylinder # 3, the fourth cylinder # 4, and the second cylinder # 2.

  The operating state of the engine 1 is controlled by an ECU (Electronic Control Unit) described later.

-Variable valve mechanism-
In the engine 1 as described above, the variable valve mechanism 30 is provided in the vicinity of the intake camshaft 23. Hereinafter, the configuration of the variable valve mechanism 30 will be described with reference to FIGS.

  The variable valve mechanism 30 is a mechanism for continuously changing the operating angle and valve lift amount (maximum lift amount) of the intake valve 21, and is arranged between the intake cam 23 a of the intake cam shaft 23 and the rocker arm 26. It is installed.

  Here, the operating angle of the intake valve 21 is an angle range from the valve opening timing IVO to the valve closing timing IVC of the intake valve 21 (expressed by a crank angle in FIG. 9), as shown in FIG. Further, the valve lift amount (maximum lift amount) is a valve movement amount when the intake valve 21 moves (lifts) to the lowermost part of the operating range when the valve is opened. These operating angles and valve lift amounts are changed in synchronization with each other by the variable valve mechanism 30. For example, the valve lift amount decreases as the operating angle decreases. Further, as the operating angle decreases, the valve opening timing IVO and the valve closing timing IVC of the intake valve 21 approach each other, the valve opening period is shortened, and the intake air amount per cylinder is decreased.

  The variable valve mechanism 30 includes a rocker shaft 31, a control shaft 32, an actuator 33, and a variable valve lift mechanism 40.

  The rocker shaft 31 is a cylindrical member extending along a direction parallel to the intake camshaft 23 (cylinder arrangement direction, F / R direction indicated by arrows in FIG. 2), and is provided in the cylinder head 11 at regular intervals. The plurality of support walls 17, 17 are attached in a state in which movement in the axial direction and the circumferential direction is restricted. The direction in which the rocker shaft 31 extends is referred to as the “axial direction”.

  The control shaft 32 is inserted into the rocker shaft 31 so as to be movable in the axial direction. The control shaft 32 is advanced and retracted in the axial direction (F direction or R direction shown in FIGS. 2 and 3) by the actuator 33.

  The number of variable valve lift mechanisms 40 is the same as the number of cylinders, and is externally mounted on the rocker shaft 31 so as to correspond to each cylinder 12. The variable valve lift mechanism 40 includes an input arm 41, an output arm 42, and a slider gear 43.

  The input arm 41 includes a cylindrical housing 41a. A helical spline 41b that meshes with an input-side helical spline 43a of a slider gear 43 described later is formed on the inner peripheral surface of the housing 41a. A pair of support pieces 41c and 41c protruding outward in the radial direction is provided on the outer periphery of the housing 41a, and a roller 41e is disposed between the pair of support pieces 41c and 41c. The roller 41e is rotatably supported by a rotation shaft 41d parallel to the rocker shaft 31.

  Cylindrical output arms 42 and 42 are arranged on both sides of the input arm 41 in the axial direction. Each output arm 42 includes a cylindrical housing 42a. A helical spline 42b that meshes with the output-side helical spline 43b of the slider gear 43 is formed on the inner peripheral surface of the housing 42a. Further, a nose 42c is provided on the outer periphery of the housing 42a so as to protrude outward in the radial direction. The nose 42c is processed into a substantially triangular shape, and a cam surface 42d whose one side is curved in a concave shape.

  A slider gear 43 is disposed in an internal space defined by the input arm 41 and the two output arms 42 and 42. The slider gear 43 is externally mounted on the rocker shaft 31 so as to be movable in the axial direction in conjunction with the control shaft 32.

  The slider gear 43 is processed into a substantially cylindrical shape having a through hole 43c at the center. An input-side helical spline 43 a that engages with the helical spline 41 b of the input arm 41 is machined in the central portion of the slider gear 43 in the axial direction. Further, output-side helical splines 43b that are engaged with the helical splines 42b of the output arm 42 are respectively machined at both ends of the slider gear 43 in the axial direction. The output side helical spline 43b has a smaller outer diameter than the input side helical spline 43a. Further, the input side helical spline 43a and the output side helical spline 43b are processed so that the directions of twisting of teeth are opposite to each other.

  The roller 41e of the input arm 41 is always pressed against the intake cam 23a by the elastic force of the lost motion spring 50 disposed in a compressed state on the cylinder head 11. On the other hand, the roller 26 a of the rocker arm 26 is pressed against the base circular portion of the housing 42 a of the output arm 42 or the cam surface 42 d of the nose 42 c by the valve spring 25 of the intake valve 21. Thus, the input arm 41 is swung by the rotation of the intake cam 23a, and the intake valve 21 is lifted via the rocker arm 26 by the output arm 42 that swings integrally with the input arm 41. .

  Next, the coupling | bonding form of the slider gear 43, the rocker shaft 31, and the control shaft 32 is demonstrated.

  The slider gear 43 is provided with a long hole (through hole) 43d extending in the circumferential direction between the input side helical spline 43a and one output side helical spline 43b. The rocker shaft 31 is formed with a long hole (through hole) 31a extending in the axial direction at a position corresponding to the long hole 43d in the circumferential direction of the slider gear 43. Further, an insertion hole 32 a is formed in the control shaft 32 at a location corresponding to the long hole 31 a of the rocker shaft 31.

  Then, the rocker shaft 31 is inserted into the through hole 43 c of the slider gear 43, and the locking pin 44 is inserted at a location where the long hole 43 d of the slider gear 43 intersects with the long hole 31 a of the rocker shaft 31. Is fixed to the insertion hole 32 a of the control shaft 32 inserted into the rocker shaft 31.

  The slider gear 43 assembled in this way operates as follows.

  First, the control shaft 32 is movable in the axial direction with respect to the rocker shaft 31 within the range of the axial length of the long hole 31 a of the rocker shaft 31. Further, since the slider gear 43 is fixed in the axial position with respect to the control shaft 32 by the engagement of the locking pin 44 and the elongated hole 43d, when the control shaft 32 moves in the axial direction by driving the actuator 33, In conjunction with this, the slider gear 43 moves in the axial direction. On the other hand, since the slider gear 43 can rotate with respect to the control shaft 32 within the range of the circumferential length of the long hole 43d, when the torque of the intake camshaft 23 is transmitted to the input arm 41, the slider gear 43 Oscillates around the rocker shaft 31.

  In such a variable valve lift mechanism 40, the input side helical spline 43a of the slider gear 43 and the helical spline 41b of the input arm 41 are supported by being engaged with each other. Similarly, the output-side helical spline 43b of the slider gear 43 and the helical spline 42b of the output arm 42 are engaged with each other and supported.

  Accordingly, the slider gear 43 is moved in the axial direction by the forward / backward movement of the control shaft 32, and the relative position in the axial direction between the slider gear 43, the input arm 41, and the output arms 42, 42 is changed. Twisting forces in opposite directions are applied to the arm 42. As a result, the input arm 41 and the output arm 42 rotate relative to each other, and the relative phase difference between the input arm 41 (roller 41e) and the output arm 42 (nose 42c) is changed.

  Thus, when the relative phase difference between the roller 41e of the input arm 41 and the nose 42c of the output arm 42 is changed, the operating angle and the valve lift amount of the intake valve 21 are changed. When the relative phase difference is the smallest (when the roller 41e and the nose 42c are closest to each other in the circumferential direction of the variable valve lift mechanism 40), the operating angle and the valve lift amount of the intake valve 21 are the smallest. . Conversely, when the relative phase difference is the largest (when the roller 41e and the nose 42c are in the most separated state in the circumferential direction of the variable valve lift mechanism 40), the operating angle and the valve lift amount of the intake valve 21 are the largest. Become.

  In the variable valve mechanism 30 of this example, the slider gears 43, 43 for each cylinder 12 are arranged on a common control shaft 32, so that the control shaft 32 moves forward and backward in the axial direction. Accordingly, the operating angles and valve lift amounts of the intake valves 21 of all the cylinders 12 are changed simultaneously.

  Next, the operation of the variable valve mechanism 30 will be described with reference to FIGS.

  FIG. 7 is an explanation of the operation when the relative phase difference between the input arm 41 and the output arm 42 is maximized, and (A) and (B) show a valve closing state and a valve opening state, respectively. FIG. 8 is an operation explanatory diagram in the case where the relative phase difference between the input arm 41 and the output arm 42 is minimized, and (A) and (B) show a valve closing state and a valve opening state, respectively.

  First, the operation of the variable valve mechanism 30 when the control shaft 32 is moved in the direction away from the actuator 33 (the direction of arrow F in FIGS. 2 and 3) will be described with reference to FIG.

  As shown in FIG. 7A, when the base circle portion of the intake cam 23a is in contact with the roller 41e of the input arm 41, the roller 26a of the rocker arm 26 is in contact with the base circle portion of the housing 42a of the output arm 42. In contact. For this reason, the intake valve 21 is maintained in a state where the valve lift amount is “0” (a state where the intake port 15 of the engine 1 is closed).

  When the roller 41e of the input arm 41 is pushed down through the lift portion of the intake cam 23a as the intake camshaft 23 rotates in the clockwise direction, the input arm 41 is counterclockwise with respect to the rocker shaft 31 (see FIG. 7 (A) arrow direction). As a result, the output arm 42 and the slider gear 43 swing together.

  As a result, the cam surface 42d formed on the nose 42c of the output arm 42 contacts the roller 26a of the rocker arm 26, and the roller 26a is pushed down by the pressing of the cam surface 42d.

  On the other hand, as shown in FIG. 7B, when the roller 26a of the rocker arm 26 is pressed by the cam surface 42d, the rocker arm 26 swings around the contact portion with the lash adjuster 27, and the intake valve 21 is moved. The valve is opened.

  As described above, when the control shaft 32 moves to the maximum in the direction away from the actuator 33, the relative phase difference between the roller 41 e of the input arm 41 and the nose 42 c of the output arm 42 around the axis of the rocker shaft 31. Is the maximum.

  Thereby, when the intake cam 23a pushes down the roller 41e to the maximum extent, the rocking amount (swing range) of the rocker arm 26 becomes the largest, and the intake valve 21 is opened and closed with the maximum operating angle and valve lift amount.

  Next, with reference to FIG. 8, the operation of the variable valve mechanism 30 when the control shaft 32 is moved in the direction (arrow R direction in FIGS. 2 and 3) close to the actuator 33 as much as possible will be described.

  As shown in FIG. 8A, when the base circle portion of the intake cam 23a is in contact with the roller 41e of the input arm 41, the contact position between the output arm 42 and the roller 41e is maximized from the cam surface 42d. Is far away. When the roller 41e of the input arm 41 is pushed down by the lift portion of the intake cam 23a due to the rotation of the intake cam shaft 23, the input arm 41 and the output arm 42 rotate together.

  However, in this case, since the contact position between the output arm 42 and the roller 41e is farthest from the cam surface 42d, the output arm 42 until the roller 26a of the rocker arm 26 is pushed down by the cam surface 42d is started. The amount of rotation is larger than that shown in FIG. Further, when the roller 41e of the input arm 41 is pushed down by the lift portion of the intake cam 23a, the range of the cam surface 42d contacting the roller 41e is reduced to only a part of the base end side of the nose 42c. For this reason, the rocking | fluctuation amount (swinging range) of the rocker arm 26 according to depression of the roller 41e by the lift part of the intake cam 23a becomes small.

  On the other hand, as shown in FIG. 8B, when the rocker arm 26 swings small, the intake valve 21 is opened with a smaller valve lift.

  Further, when the control shaft 32 moves to the maximum in the direction approaching the actuator 33, the relative phase difference between the roller 41e and the nose 42c around the axis of the rocker shaft 31 is minimized.

  Thereby, when the intake cam 23a pushes down the roller 41e to the maximum extent, the displacement amount of the roller 41e becomes the smallest, and the intake valve 21 is opened and closed with the minimum operating angle and valve lift amount.

-ECU-
The ECU 100 includes a CPU, a ROM, a RAM, a backup RAM, and the like. The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores calculation results from the CPU, data input from each sensor, and the like. The backup RAM is a non-volatile memory that stores data to be saved when the engine 1 is stopped. is there.

  As shown in FIG. 2, the ECU 100 detects the water temperature sensor 101, the air flow meter 102 that detects the intake air amount, the intake air temperature sensor 103 that detects the intake air temperature, and the rotation angle (engine speed) of the crankshaft 10. Various sensors for detecting the operating state of the engine 1 such as the crank position sensor 104 are connected. The ECU 100 controls the injector 2, the spark plug 3, the electronically controlled throttle valve 4 that adjusts the intake air amount, the actuator 33 of the variable valve mechanism 30 and the like based on the outputs of the various sensors described above. Various controls of the engine 1 are executed. Further, the ECU 100 executes the following operating angle variation detection control.

-Operation angle variation detection control-
A method of detecting the operating angle variation employed in this example will be described.

  In this example, the operating angle variation between the cylinders 12 (# 1 to # 4) of the engine 1 is detected based on the change amount of the crank angular velocity. Specifically, based on the output signal of the crank position sensor 104, the time required for each cylinder 12 (# 1 to # 4) from T1 (30 ° CA before TDC (top dead center) to TDC) shown in FIG. ) And T2 (time required from ATDC 60 ° CA to ATDC 90 ° CA) and the time difference between T1 and T2 [T30 difference = T1-T2] for each cylinder 12 (# 1- # 4). And variation in the operating angle is detected based on the T30 difference calculation result. Such operation angle variation detection is a process executed in step ST4 of the flowchart of FIG. 10 described later.

  When detecting variation in operating angle between the cylinders 12 (# 1 to # 4) based on the T30 difference as described above, for example, as shown in FIG. (Signal / Noise) is good and variation in operating angle can be detected. However, as shown in FIG. 12B, when the variation in operating angle is small, S / N cannot be obtained, and the operating angle is small. Variations cannot be detected. A method for solving such a problem will be described below.

  First, the relationship between the intake air amount, the boost pressure, and the operating angle will be described. When the operating angle varies between the cylinders 12 of the engine 1, as shown in FIG. 13, the difference in the intake air amount between the cylinders 12 becomes the difference in valve opening area (the difference in the area shown by hatching in FIG. 13). , [Boost pressure pm] × [operation angle]. Here, when the rotation speed of the engine 1 is increased with the air charging efficiency being constant, the boost pressure pm is increased as shown in FIG. 14, so the intake air amount (intake air amount) between the cylinders 12 (# 1 to # 4). (Proportional to [boost pressure pm] × [action angle]) increases (A / F difference). In the present invention, paying attention to such a relationship, the difference in the intake air amount between the cylinders 12 (# 1 to # 4) (that is, between the cylinders) is increased by increasing the rotational speed of the engine 1 only at the time of detecting the operating angle variation. The feature is that the detection of the variation in the working angle is enhanced by increasing the variation in the working angle.

  The specific processing will be described with reference to the flowchart shown in FIG. It should be noted that the operating angle variation detection control routine shown in FIG.

  First, in step ST1, it is determined whether or not the engine 1 has fully warmed up after the engine is started. If the determination result is negative, this routine is once terminated. If the determination result in step ST1 is affirmative and the engine 1 is in a stable operation state (idling operation state) after complete warm-up, ignition of all cylinders 12 (# 1 to # 4) is performed in step ST2. After setting the time condition to the same condition, the process proceeds to step ST3.

  In step ST2, the ignition timing condition is set to the same condition. If the ignition timing is controlled for each cylinder 12 (# 1 to # 4), the operating angle variation is corrected by the ignition timing control. This is to prevent the problem that the variation in the operating angle that should be detected does not appear.

  In step ST3, the engine speed is increased by increasing the amount of intake air by controlling the electronically controlled throttle valve 4 for the purpose of creating a situation in which the operating angle variation between the cylinders 12 (# 1 to # 4) can be easily detected. To increase. As described above, when the engine speed is increased from the idling operation state, the A / F difference between the cylinders 12 (# 1 to # 4), that is, the variation in the intake air amount increases as described above (see FIG. 14). Detectability of working angle variation can be improved. Here, the engine speed at the time of detecting the operating angle variation may be increased to a speed at which the change amount of the crank angular speed as shown in FIG. The number of revolutions is empirically determined in advance based on experiments and calculations.

  In step ST4, T1 and T2 shown in FIG. 11 are obtained for each cylinder 12 (# 1 to # 4) based on the output signal of the crank position sensor 104, and the above-described T30 difference (T1-T2) is obtained. Calculated for each cylinder 12 (# 1 to # 4), variation in T30 difference between the cylinders 12 (# 1 to # 4), that is, variation in working angle between the cylinders 12 (# 1 to # 4). Is detected.

  In step ST5, it is determined whether or not the operating angle variation between the cylinders 12 (# 1 to # 4) detected in step ST4 is within a predetermined allowable range. When the operating angle variation is within the allowable range, The routine is temporarily terminated. When the operating angle variation between the cylinders 12 (# 1 to # 4) exceeds the allowable range, the process proceeds to step ST6, where the actuator 33 of the control shaft 32 is driven and controlled, and all the cylinders 12 (# 1 to # 4) are controlled. The variation of the working angle is suppressed by performing a correction of uniformly increasing the working angle. Thereafter, this routine is terminated.

  As described above, in this example, even when the operating angle variation is small, such as during idling, the engine speed is set only when the operating angle variation between the cylinders 12 (# 1 to # 4) is detected. Since the operating angle variation is increased by increasing the operating angle, the operating angle variation between the cylinders 12 (# 1 to # 4) can be accurately detected. Then, based on the detection result of the operating angle variation obtained in this way, the variable valve mechanism 30 is controlled to adjust the operating angle of the intake valve 21, whereby the combustion of the engine 1 in the idling or partial region or the like. The state can be stabilized.

-Other embodiments-
In the above example, the variable valve mechanism 30 is provided only on the intake valve 21. However, the present invention is not limited to this, and the variable valve mechanism 30 is used as both the intake valve 21 and the exhaust valve 22. It can also be applied to the engine provided. Further, the present invention can be applied to an engine provided with a variable valve timing (VVT) mechanism in addition to the variable valve mechanism 30.

  In the above example, the present invention is applied to the engine 1 including the variable valve mechanism 30 that adjusts the operating angle of the intake cam 23a by the forward / backward movement of the control shaft 32. However, the present invention is not limited to this. The present invention can also be applied to an engine equipped with another variable valve mechanism such as a mechanism that makes the operating angle of the intake cam 23a variable by rotationally driving the control shaft.

  In the above example, an example in which the present invention is applied to control of a four-cylinder gasoline engine has been described. However, the present invention is not limited to this, and for example, a multi-cylinder gasoline having any other number of cylinders such as a cylinder six-cylinder gasoline engine It can also be applied to engine control. In addition, the present invention is not limited to a gasoline engine, but can be applied to control of an ignition type engine using other fuel such as LPG (liquefied petroleum gas) and LNG (liquefied natural gas), for example. It can also be applied to control of an in-cylinder direct injection engine.

It is a schematic structure figure showing an example of an engine to which the present invention is applied. FIG. 2 is a diagram illustrating a plan view of a cylinder head of the engine of FIG. 1 and a block diagram of a control system. It is a perspective view which shows the principal part structure of a variable valve mechanism. It is a disassembled perspective view which shows the principal part structure of a variable valve mechanism. It is a disassembled perspective view which extracts and shows the slider gear, rocker shaft, control shaft, etc. of a variable valve mechanism. It is a perspective view which shows the principal part structure of a variable valve mechanism. It is operation | movement explanatory drawing of a variable valve mechanism. It is operation | movement explanatory drawing of a variable valve mechanism. It is a figure which shows the operating angle and valve lift amount of the intake valve which are made variable by the variable valve mechanism. It is a flowchart which shows an example of the working angle dispersion | variation detection control which ECU performs. It is explanatory drawing of T30 difference used for the detection of an operating angle dispersion | variation. It is explanatory drawing of the reason which becomes impossible to detect in the method which detects a working angle dispersion | variation based on T30 difference. It is a graph which shows the relationship between the difference of the intake air amount between cylinders, a boost pressure, and a working angle. It is a graph which shows the relationship between A / F and boost pressure for each cylinder, and engine speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Injector 3 Spark plug 4 Throttle valve 10 Crankshaft 11 Cylinder head 12 Cylinder 13 Cylinder block 1a Piston 1b Combustion chamber 21 Intake valve 22 Exhaust valve 23 Intake camshaft 23a Intake cam 24 Exhaust camshaft 24a Exhaust cam 30 Variable valve Mechanism 31 Rocker shaft 32 Control shaft 33 Actuator 40 Variable valve lift mechanism 100 ECU
104 Crank position sensor

Claims (2)

A control device applied to an internal combustion engine provided with a variable valve mechanism that varies the operating angle of an engine valve provided in each of a plurality of cylinders,
Detection means for detecting operating angle variation between the plurality of cylinders and control for executing control for increasing the engine speed by changing the operating state of the internal combustion engine when detecting operating angle variation between the cylinders And a control device for the internal combustion engine.   A crank position sensor that detects a crank angle of a crankshaft of the internal combustion engine is used, and a variation in operating angle between the cylinders is detected based on a variation amount of a crank angular speed obtained from an output of the crank position sensor. The control device for an internal combustion engine according to claim 1.

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