JP2007077948A - Variable valve train for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promptly eliminate an incomplete valve-closing state even if the incomplete valve-opening state is generated in closing a valve by popping up a lash adjuster. <P>SOLUTION: This variable valve train 3 for an internal combustion engine 1 includes the hydraulic lash adjuster 25 and an end pivot type rocker arm 24 and allows relative phase differences of valve striking members 42A and 42B with respect to a cam member 41 to be struck on a slider gear 43 to be varied by axially displacing a control shaft 32. Each of the valve striking members 42A and 42B has a cam surface 42d in contact with the rocker arm 24, and the cam surface 42d is provided with a minus lift section DL for permitting the movement of the other end position of the rocker arm 24 from a position in zero lift to the anti-lift side. When the variable valve train is brought into an incomplete valve-closing state, the valve striking members 42A and 42B are so moved as to face the minus lift sections DL of the cam surfaces 42d thereof to the rocker arm 24. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism that makes it possible to change operating characteristics such as lift amounts and operating angles of intake valves and exhaust valves in accordance with the operating state of an internal combustion engine.

  As a conventional variable valve mechanism for this type of internal combustion engine, for example, there is one as shown in Patent Document 1.

  In this conventional example, for example, an end pivot type rocker arm with a roller whose one end is supported by a hydraulic lash adjuster is used, and an intermediary drive mechanism is disposed between the cam of the camshaft and the rocker arm.

  The intermediary drive mechanism makes the input portion (cam hitting member) and the two swing cams (valve striking member) relative to each other by a slider gear that is linked to the axial movement of the control shaft inserted through the central hole of the rocker shaft. To change the relative phase difference between the roller provided on the outer diameter side of the input portion and the nose provided on the outer diameter side of the rocking cam, thereby adjusting the lift amount and working angle of the valve. It has become. The lift amount and operating angle of the valve can be adjusted in a range from zero to a predetermined size.

When the relative phase difference is set to the minimum within the specified range, even if the input portion and the swing cam are swung in one rotation direction by the camshaft cam, the rocker arm does not tilt at all, and the lift amount and working angle of the valve Is set to zero. On the other hand, when the relative phase difference is set to the maximum within the specified range, the rocker arm is inclined to the maximum when the input portion and the swing cam are swung in one rotation direction by the camshaft cam, and the lift amount of the valve and The working angle is maximized.
JP 2001-263015 A

  In the above conventional example, an abnormality such that the intake valve or the exhaust valve is not completely closed when it is closed but is slightly opened (incompletely closed state) may occur depending on the operating state of the internal combustion engine.

  Specifically, on the intake valve side, when the internal combustion engine speed increases and valve surging occurs, a so-called jump phenomenon occurs in which the lift amount when the intake valve opens is larger than the steady lift amount. There are things to do. In such a case, the plunger of the lash adjuster on the intake valve side may protrude from the steady position so as to keep the tappet clearance of the intake valve at zero. This phenomenon is the pump up of the lash adjuster, and when this pump up occurs, there is a possibility that the incomplete valve closing state occurs every time the intake valve is closed thereafter.

  On the exhaust valve side, when the peak of exhaust pulsation (back pressure) increases, resistance when the exhaust valve is closed increases, so that an incomplete valve closing state may occur when the exhaust valve is closed. When such an incomplete valve closing state occurs, the plunger of the lash adjuster on the exhaust valve side may protrude beyond the steady position. This phenomenon is the pump up of the lash adjuster. When such a pump up occurs, there is a possibility that the exhaust valve is incompletely closed each time the exhaust valve is closed thereafter.

  Incidentally, if the intake valve or the exhaust valve becomes incompletely closed when the valve is closed, the combustion condition in the cylinder is deteriorated. Therefore, it is desirable to quickly eliminate the abnormality of the incompletely closed state.

  The present invention provides a variable valve mechanism for an internal combustion engine having a hydraulic lash adjuster and an end pivot type rocker arm, even if an incomplete valve closing state occurs when the lash adjuster is pumped up and the valve is closed. The goal is to eliminate it as soon as possible.

  The present invention tilts an end pivot type rocker arm, one end of which is supported by a hydraulic lash adjuster as the camshaft cam rotates, thereby pushing the intake valve and exhaust valve on the other end of the rocker arm. And a variable valve mechanism for an internal combustion engine that can change the operating characteristics of at least one of an intake valve and an exhaust valve, and is controlled by a central hole of a rocker shaft fixedly supported in parallel with the camshaft on the cylinder head A shaft is inserted so as to be axially displaceable, and a slider gear is externally mounted on the outer periphery of the rocker shaft so as to be interlocked with the control shaft. Exterior through the opposite helical spline, the control shaft It is configured to change the relative phase difference of the valve striking member with respect to the cam striking member by displacing the cam striking member, and the valve striking member has a cam surface that contacts the rocker arm. The rocker arm is characterized in that a minus lift section is provided which allows the other end position of the rocker arm to move from the position of zero lift to the non-lift side.

  In the first place, the incomplete closing state of the valve is caused by the pumping up of the lash adjuster. For this pump-up, refer to the explanation given in the conventional example. If the intake valve or the exhaust valve is in an incompletely closed state in the compression stroke, the in-cylinder compression ratio is reduced, and if the exhaust valve is in an incompletely closed state in the intake stroke, There is a risk that the unburned gas will be easily discharged into the exhaust system, and the combustion conditions will deteriorate.

  According to this configuration, for example, when an abnormality that causes the valve to be incompletely closed occurs, the minus lift section on the cam surface of the valve striking member is temporarily opposed to the rocker arm. It becomes possible.

  As a result, the valve that is normally biased in the valve closing direction by the valve spring pushes up the other end side of the rocker arm, and the plunger of the lash adjuster is pushed on one end side of the rocker arm with the substantially middle portion in the longitudinal direction of the rocker arm as a fulcrum. Since it is pushed down, the pump up of the lash adjuster is eliminated and the valve can be completely closed when the valve is closed.

  As described above, even when the valve is incompletely closed when the valve is closed, it is possible to cope with the valve closing relatively quickly.

  Preferably, the valve striking member has a cylindrical housing, a projecting piece projecting radially outward is provided at a predetermined circumferential position on the outer periphery of the housing, and a base side of the projecting piece is provided. A skirt portion extending in one circumferential direction is provided, and on the outer peripheral surface of the skirt portion, a base circle that is concentric with the outer periphery of the housing is provided in the projecting piece side region, and in the anti-projection side region. A sloped curved surface is provided in which the radial dimension from the center of the output arm gradually decreases toward the protruding piece, and the cam surface is a region from the protruding end of the protruding piece to the end of the skirt, From the projecting end of the projecting piece to the end of the skirt part is a plus lift section for continuously increasing or decreasing the valve lift amount, and the base circle of the skirt part makes the valve lift amount zero. Zero lift section Is further be configured to obliquely descending curved surface of the skirt portion is negative lift section for allowing movement of the counter-lifting direction of the valve.

  This configuration specifies the shape of the cam surface of the valve striking member, and a valve striking member having such a cam surface can be manufactured relatively easily.

  Preferably, in the variable valve mechanism of the internal combustion engine, when an abnormality occurs that causes the valve to be incompletely closed, the valve striking member is opposed to the rocker arm in the negative lift section of its cam surface. It can be set as the structure moved so that it may arrange.

  According to this configuration, as described above, the valve that is normally urged in the valve closing direction by the valve spring pushes up the other end side of the rocker arm, and the rocker arm has a substantially fulcrum in the longitudinal direction as a fulcrum. Since the plunger of the lash adjuster is pushed down on one end side, pumping up of the lash adjuster is eliminated and the valve can be completely closed when the valve is closed.

  The present invention tilts an end pivot type rocker arm, one end of which is supported by a hydraulic lash adjuster as the camshaft cam rotates, thereby pushing the intake valve and exhaust valve on the other end of the rocker arm. In addition, this is a variable valve mechanism for an internal combustion engine that can change at least the operating characteristics of the intake valve, and the control shaft is axially displaced in the center hole of the rocker shaft fixedly supported in parallel with the camshaft on the cylinder head The slider gear is mounted on the outer periphery of the rocker shaft so as to be interlocked with the control shaft, and the cam hitting member and the valve hitting member are adjacent to each other in the axial direction on the slider gear. And displace the control shaft in the axial direction. The relative phase difference of the valve striking member with respect to the cam striking member is changed, and when the exhaust valve is incompletely closed when the valve is closed, the lift amount of the intake valve by the valve striking member Is made smaller than the target.

  According to this configuration, when the exhaust valve is in an incompletely closed state, if the lift amount of the intake valve is made smaller than the target, the introduction amount of the air-fuel mixture from the intake port can be reduced from the target introduction amount. Become. As a result, the in-cylinder pressure due to combustion is reduced and the peak of exhaust pulsation (back pressure) is reduced. After that, the elastic restoring force of the valve spring overcomes the exhaust resistance when the exhaust valve is closed, The plunger of the lash adjuster is pushed down, and the lash adjuster pump-up phenomenon is eliminated. As described above, the cause of the exhaust valve being incompletely closed can be removed immediately, so that the exhaust valve can be completely closed.

  Preferably, in the variable valve mechanism for the internal combustion engine, the valve striking member has a cam surface that contacts the rocker arm, and the other end position of the rocker arm is set on the cam surface from the position at the time of zero lift to the non-lift side. A negative lift section that allows movement to the side is provided, and when the incomplete valve closing state occurs, the valve striking member can be configured to move so that the negative lift section of the cam surface thereof faces the rocker arm. .

  This configuration specifies the shape of the cam surface of the valve striking member, and a valve striking member having such a cam surface can be manufactured relatively easily.

  The present invention tilts an end pivot type rocker arm, one end of which is supported by a hydraulic lash adjuster as the camshaft cam rotates, thereby pushing the intake valve and exhaust valve on the other end of the rocker arm. And a variable valve mechanism for an internal combustion engine that can change the operating characteristics of at least one of an intake valve and an exhaust valve, and is controlled by a central hole of a rocker shaft fixedly supported in parallel with the camshaft on the cylinder head A shaft is inserted so as to be axially displaceable, and a slider gear is externally mounted on the outer periphery of the rocker shaft so as to be interlocked with the control shaft. Exterior through the opposite helical spline and if necessary the controller The shaft is displaced in the axial direction by driving means to change the relative phase difference of the valve striking member with respect to the cam striking member, and an abnormality that causes the valve to be incompletely closed when the valve is closed. An abnormality detecting means for detecting, and a countermeasure means for driving the driving means so as to reduce a valve lift amount by the valve striking member when an abnormality is detected by the abnormality detecting means.

  According to this configuration, when either the intake valve or the exhaust valve is in an incompletely closed state, it is possible to cope with an abnormality with the corresponding valve striking member.

  Preferably, in the variable valve mechanism for the internal combustion engine, the abnormality detection unit determines whether or not the abnormality has been detected based on a sensor that detects a position on the other end side of the rocker arm and a detection output of the sensor. Means.

  According to this configuration, it is possible to make the abnormality detection unit relatively simple, which is advantageous in reducing the equipment cost.

  According to the present invention, even if an incomplete valve closing state occurs when the lash adjuster is pumped up and the valve is closed, it can be quickly resolved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 15 show an embodiment of the present invention.

  First, prior to the description of the characteristic configuration of the present invention, the configuration of a variable valve mechanism for an internal combustion engine which is a premise of the present invention will be described. In this example, the internal combustion engine 1 is an in-line four-cylinder DOHC engine, and an end pivot type rocker arm 24 and a hydraulic lash adjuster 25 are used. Further, in order to simplify the description of the variable valve mechanism 3, an example is given in which the operation characteristics such as the lift amount and the operating angle of only the intake valve 14 can be continuously changed.

  One end of the end pivot type rocker arm 24 is supported by a hydraulic lash adjuster 25, and the other end abuts on the tappet 14 a on the stem end side of the intake valve 14, so that the roller 24 a can rotate in the middle in the longitudinal direction. It is a supported configuration.

  The hydraulic lash adjuster 25 functions to keep the tappet clearance of the intake valve 14 always at zero. For example, as shown in FIG. 9, a bottomed cylindrical body 25a, plunger 25b, plunger spring 25c, check This is a generally known configuration having valves (check ball 25d, check ball spring 25e, and ball retainer 25f).

  The low pressure chamber 25g inside the plunger 25b is supplied with oil of an existing hydraulic system installed in the cylinder head 12. The bottom wall of the plunger 25b has a low pressure chamber 25g and a high pressure chamber. A through-hole 25i is provided for connecting and communicating with 25h. The check valve controls the hydraulic pressure of the high pressure chamber 25h and the amount of protrusion of the plunger 25b relative to the body 25a by opening and closing the through hole 25i according to the direction of the force acting on the plunger 25b.

  The variable valve mechanism 3 includes a rocker shaft 31, a control shaft 32, an actuator 33 as drive means, and a valve lift mechanism 4.

  The rocker shaft 31 is attached to a large number of partition walls 21 provided at regular intervals in the cylinder head 12 so as to be immovable in the axial direction and the circumferential direction, and is parallel to the intake camshaft 16, that is, a cylinder (combustion chamber 13). ) Along the arrangement direction.

  The control shaft 32 is inserted into the center hole of the rocker shaft 31 formed of a hollow pipe so as to be axially displaceable, and is driven forward and backward in the axial direction by the actuator 33.

  The number of valve lift mechanisms 4 is the same as the number of cylinders, and is externally mounted on the rocker shaft 31 so as to correspond to each cylinder.

  The valve lift mechanism 4 is disposed between the intake cam 17 of the intake camshaft 16 and the rocker arm 24, and includes an input arm 41 as a cam hit member and two output arms 42A and 42B as valve hitting members. And a slider gear 43. The input arm 41 and the two output arms 42A and 42B are referred to as an arm assembly as necessary.

  The input arm 41 has a cylindrical housing 41 a, and a helical spline 41 b that meshes with the center helical spline 43 a of the slider gear 43 is formed on the inner peripheral surface thereof. A pair of forks 41cL and 41cR projecting radially outward is provided on the outer periphery of the housing 41a, and a support shaft 41d parallel to the rocker shaft 31 is interposed between the pair of forks 41cL and 41cR. A roller 41e is rotatably supported.

  The two output arms 42A and 42B have the same shape, and both have a cylindrical housing 42a, and a helical spline 42b that meshes with the side helical spline 43b of the slider gear 43 is formed on the inner peripheral surface thereof. ing. Further, a nose 42c is provided on the outer periphery of the housing 42a as a protruding piece that protrudes radially outward. The nose 42c is formed in a substantially triangular shape in a side view, and one side thereof is a cam surface 42d. The cam surfaces 42d of the output arms 42A and 42B come into contact with the roller 24a of the rocker arm 24, and will be described in detail later.

  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, and the input arm 41 and the two output arms 42A and 42B are externally mounted on the outer diameter side thereof. .

  The slider gear 43 is formed in a cylindrical shape having a through hole 43c at the center, and a center helical spline 43a that meshes with the helical spline 41b of the input arm 41 is provided at the center in the axial direction on the outer periphery, and a shaft on the outer periphery. Side helical splines 43b meshing with the helical splines 42b of the output arms 42A and 42B are formed on both sides in the direction. The side helical spline 43b has a smaller outer diameter than the center helical spline 43a. The center helical spline 43a and the side helical spline 43b are formed so that the inclination directions of the teeth are opposite.

  The roller 41e of the input arm 41 is urged so as to be always pressed against the intake cam 17 by a spring 26 called a lost motion spring disposed in the cylinder head 12 in a compressed state. The roller 24a of the rocker arm 24 is pressed against the cam surface 42d of the housing 42a of the output arms 42A and 42B by the valve spring 14b of the intake valve 14.

  Here, the slider gear 43 will be described in connection with the rocker shaft 31 and the control shaft 32.

  In the slider gear 43, between the center helical spline 43a and one side helical spline 43b, there is provided a long hole 43d that extends along the circumferential direction and penetrates radially inward and outward. In the rocker shaft 31, a long hole 31a that extends along the axial direction and penetrates radially inward and outward is provided at a position corresponding to the long hole 43d of the slider gear 43. Further, an insertion hole 32 a is provided at a position of the control shaft 32 corresponding to the long hole 31 a of the rocker shaft 31.

  Then, the rocker shaft 31 is inserted into the through hole 43c of the slider gear 43, and a locking pin 44 is inserted at a location where the long hole 43d of the slider gear 43 and the long hole 31a of the rocker shaft 31 intersect. One end of the pin 44 is fixed to the insertion hole 32 a of the control shaft 32 inserted into the control shaft 32. In order to allow movement of the locking pin 44 in the long hole 43 d of the slider gear 43, the axial width of the long hole 43 d of the slider gear 43 is slightly larger than the diameter of the locking pin 44.

The slider gear 43 assembled in this way operates as follows.
(A) The locking pin 44 can move along the long hole 31 a of the rocker shaft 31. For this reason, when the control shaft 32 is moved in the axial direction by the actuator 33, the slider gear 43 moves in the axial direction in conjunction with the control shaft 32.
(B) Since the locking pin 44 is inserted into the elongated hole 43 d of the slider gear 43, when the torque of the intake camshaft 16 is transmitted to the input arm 41, the slider gear 43 swings around the rocker shaft 31. To do.

  In such a valve lift mechanism 4, the slider gear 43 is moved in the axial direction together with the control shaft 32, and the relative position in the axial direction between the slider gear 43 and the arm assembly (input arm 41 and output arms 42A and 42B) is changed. By doing so, torsional forces in opposite directions are applied to the input arm 41 and the output arms 42A and 42B. As a result, the input arm 41 and the output arms 42A and 42B rotate relative to each other, and the relative phase difference between the input arm 41 (roller 41e) and the output arms 42A and 42B (nose 42c) is changed.

  In the variable valve mechanism 3, the valve lift mechanism 4 for each cylinder is fixed to a common control shaft 32, so that all cylinders are moved along with the axial movement of the control shaft 32. The lift amount of the intake valve 14 is simultaneously changed. However, the valve lift mechanism 4 for each cylinder can be individually operated, and the present invention can be applied to such a form.

  Next, the basic operation will be described.

  First, in the state where the control shaft 32 is moved to the maximum in the direction away from the actuator 33 (the arrow F direction in FIG. 3), the roller 41e of the input arm 41 around the axis of the rocker shaft 31 and the output arm 42A, The relative phase difference with the nose 42c of 42B becomes the maximum.

  In this state, as shown in FIG. 7A, the rocker arm 24 does not tilt during the period when the base circle portion of the intake cam 17 is in contact with the roller 41e of the input arm 41, so the lift amount of the intake valve 14 Becomes zero (the intake port 12a is closed).

  Here, as shown in FIG. 7B, when the roller 41e of the input arm 41 is pushed down to the maximum by the convex portion of the intake cam 17 with the clockwise rotation of the intake cam shaft 16, the input arm 41 is While rotating in the direction of the arrow A (counterclockwise), the output arms 42A and 42B and the slider gear 43 are rotated together. As a result, as shown in FIG. 7B, the roller 24a of the rocker arm 24 is pushed down by the nose 42c of the output arms 42A and 42B, and the rocker arm 24 tilts with the contact portion with the lash adjuster 25 as a fulcrum. 14 is pushed down to open at the maximum lift and operating angle.

  On the other hand, in the state where the control shaft 32 is moved to the maximum in the direction approaching the actuator 33 (the arrow R direction in FIG. 3), the relative phase difference between the roller 41e and the nose 42c around the axis of the rocker shaft 31 is minimum. Become.

  In this state, as shown in FIG. 8A, the rocker arm 24 does not tilt during the period in which the base circle portion of the intake cam 17 is in contact with the roller 41e of the input arm 41, so the lift amount of the intake valve 14 Becomes zero (the intake port 12a is closed).

  Here, as shown in FIG. 8B, when the roller 41e of the input arm 41 is pushed down to the maximum by the convex portion of the intake cam 17 as the intake cam shaft 16 rotates in the clockwise direction, Although the output arms 42A and 42B are integrally rotated counterclockwise (arrow A direction), the nose 42c does not contact the roller 24a of the rocker arm 24, so the rocker arm 24 does not tilt at all and the intake valve The lift amount of 14 is maintained at zero.

  Next, a configuration relating to the features of the present invention will be described with reference to FIGS.

  In short, in this embodiment, when the intake valve 14 and the exhaust valve 15 are closed, it is individually examined whether or not an abnormality that causes the valve to be incompletely closed occurs. It is devised to make it possible to close the valve quickly when it occurs.

  Specifically, first, as shown in FIG. 10, a skirt portion 42e extending in one circumferential direction is provided on the base side of the nose 42c of the output arms 42A and 42B.

  Further, on one side of the nose 42c, a region from the projecting end to the middle of the base side is a linear shape, and a region connecting the end of the linear shape portion and the start end of the skirt portion 42e is a curved shape. .

Furthermore, a base circle 42e ₁ that is concentric with the outer periphery of the housing 42a (see a two-dot chain line in FIG. 10) is provided in the region near the nose 42c on the outer peripheral surface of the skirt 42e, and the region near the anti-nose 42c. Is provided with an inclined curved surface 42e _{2 in} which the radial dimension from the center P of the output arms 42A and 42B gradually decreases toward the anti-nose 42c.

  The range from the protruding end of the nose 42c to the end of the skirt portion 42e is a cam surface 42d that comes into contact with the roller 24a of the rocker arm 24.

In such a cam surface 42d, a portion from the protruding end of the nose 42c to the front of the skirt portion 42e is a plus lift section CL for continuously increasing / decreasing the lift amount of the intake valve 14, and the base of the skirt portion 42e. The circle 42e ₁ is used as a zero lift section UL for making the lift amount of the intake valve 14 zero, and the inclined curved surface 42e ₂ of the skirt portion 42e allows movement of the intake valve 14 in the anti-lift direction. Minus lift section DL.

  Further, as shown in FIG. 2, in order to detect the occurrence of an abnormality that causes the intake valve 14 and the exhaust valve 15 to be incompletely closed when the valve is closed, the respective rocker arms 24 on the intake side and the exhaust side are detected. Sensors 5 and 6 for detecting the position of the other end of the rocker arm 24 are arranged opposite to each other on the other end side (the intake valve 14 side and the exhaust valve 15 side).

  The sensors 5 and 6 are generally known various non-contact proximity sensors, and detection outputs of the sensors 5 and 6 are input to the control device 7.

  The control device 7 is configured by an engine ECU that controls the operation of the internal combustion engine 1, but may be an independent ECU different from the engine ECU.

  The control device 7 has a function of controlling the actuator 33 as necessary, and whether or not an abnormality has occurred so that the intake valve 14 and the exhaust valve 15 are incompletely closed based on detection outputs of the sensors 5 and 6. It is configured to be capable of executing at least a function and the like for appropriately detecting when an abnormality is detected.

  Specifically, at each timing when the intake valve 14 and the exhaust valve 15 are closed, the flow chart shown in FIG. 10 is entered, and the other ends of the rocker arms 24 on the intake side and the exhaust side based on the detection outputs of the sensors 5 and 6. A current position in the tilt direction of the intake valve 14 side or the exhaust valve 15 side is detected (step S1), and the intake valve 14 is based on the detected current position and a reference position when fully closed that is known in advance. And whether or not an abnormality such as an incompletely closed state of the exhaust valve 15 has occurred (step S2), and when it is determined that an abnormality has occurred, an abnormality corresponding to each intake valve 14 or exhaust valve 15 is taken (step S3). If it is determined that no abnormality has occurred, the process skips step S3 and returns to the operation control routine of the internal combustion engine 1 (not shown).

  The sensors 5 and 6 and the abnormality determination process (determination means) executed by the control device 7 correspond to the abnormality detection means described in the claims, and the abnormality countermeasure processing executed by the control device 7 is described in the claims. It corresponds to the coping means.

  Here, the abnormality handling will be described in detail.

  In the first place, in the internal combustion engine 1, an abnormality such that the intake valve 14 side and the exhaust valve 15 side are incompletely closed may occur depending on the operating state.

  First, in the intake valve 14, when the rotational speed of the internal combustion engine 1 increases and valve surging occurs, the lift amount when the intake valve 14 is opened (see the solid line in FIG. 12) is the steady lift amount (see FIG. 12). A so-called jump phenomenon may occur, which is larger than the two-dot chain line in FIG. In such a case, the plunger 25b of the lash adjuster 25 on the intake valve 14 side may protrude from the steady position so as to keep the tappet clearance of the intake valve 14 at zero. This phenomenon is a lash adjuster pump-up. When this pump-up occurs, every time the intake valve is closed after that, there is a risk that the valve will be in an incompletely closed state as shown in FIG. 13, for example.

  When such an abnormality occurs in the intake valve 14, an affirmative determination is made in step S2 in FIG. 11, and as a countermeasure for the abnormality in step S3 in FIG. 11, for example, as shown in FIG. By driving and rotating the output arms 42A and 42B of the valve lift mechanism 4 by a predetermined angle, for example, clockwise, the minus lift section DL on the cam surface 42d of the output arms 42A and 42B is made to face the roller 24a of the rocker arm 24.

  As a result, as shown in FIG. 14, a slight gap α is formed between the minus lift section DL on the cam surface 42d of the output arms 42A and 42B and the roller 24a of the rocker arm 24 for a moment. This gap α can be adjusted by the drop from the base circle section UL to the minus lift section DL on the cam surfaces 42d of the output arms 42A and 42B, but the intake valve 14 in the incompletely closed state shown in FIG. It is set smaller than the opening amount β.

  Immediately after this, the intake valve 14 urged toward the valve closing side by the valve spring 14b rises, and as shown in FIG. 15, the other end side of the rocker arm 24 and the roller 24a are lifted and the output arms 42A, 42B. The cam surface 42d is pressed against the minus lift section DL. Accordingly, the rocker arm 24 tilts with the roller 24a as a fulcrum so that one end thereof is lowered, so that one end of the rocker arm 24 pushes down the plunger 25b of the lash adjuster 25, and as a result, pumping up of the lash adjuster 25 is eliminated. At the same time, the intake valve 14 is completely closed.

  As described above, when the minus lift section DL on the cam surface 42d of the output arms 42A and 42B is directly opposed to the roller 24a of the rocker arm 24, the clearance α as shown in FIG. FIG. 14 shows the state in which the rocker arm 24 is lifted by the elastic restoring force of the valve spring 14b following the rotation of the output arms 42A and 42B. It is considered that there is no gap α as shown, and the state shown in FIG. 13 shifts to the state shown in FIG.

  On the other hand, on the exhaust valve 15 side, if the peak of exhaust pulsation (back pressure) increases, the resistance when closing the exhaust valve 15 increases, so that the exhaust valve 15 may be in an incompletely closed state when the valve is closed. is there. When such an incomplete valve closing state occurs, the plunger 25b of the lash adjuster 25 on the exhaust valve 15 side may protrude from the steady position. This phenomenon is the pump up of the lash adjuster. When such a pump up occurs, there is a possibility that the exhaust valve 15 is incompletely closed every time the exhaust valve 15 is closed thereafter.

  When such an abnormality of the exhaust valve 15 occurs, an affirmative determination is made in step S2 in FIG. 11 as described above, and the lift amount and action of the intake valve 14 in the intake stroke are taken as a countermeasure for the abnormality in step S3 in FIG. Adjust the angle so that it is smaller than the target. That is, the control shaft 32 is driven to rotate the output arms 42A and 42B of the valve lift mechanism 4 by a predetermined angle in a direction in which the lift amount and the operating angle of the exhaust valve 14 are smaller than the target.

  When the lift amount and operating angle of the intake valve 14 are made smaller than the target in this way, the amount of air-fuel mixture introduced from the intake port 12a can be reduced from the target introduction amount, thereby reducing the in-cylinder pressure due to combustion. Since the exhaust pulsation peak (back pressure) is lowered, the elastic restoring force of the valve spring 14b overcomes the exhaust resistance when the exhaust valve 15 is closed thereafter, and the plunger 25b of the lash adjuster 25 is pushed down. As a result, the pump-up phenomenon of the lash adjuster 25 is eliminated. Thus, measures are taken so that the exhaust valve 15 can be completely closed when the valve is next closed by quickly removing the cause of the exhaust valve 15 being incompletely closed.

  As described above, in this embodiment, when an abnormality occurs such that the intake valve 14 and the exhaust valve 15 are incompletely closed when the valve is closed, a countermeasure is taken so that the valve can be fully closed as soon as possible. As a result, the combustion conditions of the internal combustion engine can be optimized, and as a result, it is possible to contribute to improving fuel consumption and torque.

  Hereinafter, other embodiments of the present invention will be described.

  (1) In the above embodiment, the configuration in which only the operating characteristic of the intake valve 14 is variable is taken as an example. However, the operating characteristic of the exhaust valve 15 can also be variable.

  In that case, when either or both of the intake valve 14 and the exhaust valve 15 are incompletely closed when the valve is closed, the valve lift mechanism 4 corresponding to the valve in which the abnormality has occurred is used as a valve. By making the lift amount small, it is possible to cope with the complete valve closing as soon as possible after the occurrence of an abnormality.

  (2) In the above embodiment, an example using the rocker arm 24 with roller is given, but a structure without the roller 24a may be used.

  (3) In the above embodiment, in order to detect the incompletely closed state of the valves (14, 15), the sensors 5 and 6 that detect the tilt position of the other end of the rocker arm 24 are used. 15) It is also possible to use a sensor that directly detects the lift amount. The sensor for detecting the lift amount can also be a non-contact proximity sensor similar to the sensors 5 and 6 described in the above embodiment.

1 is a plan view schematically showing a variable valve mechanism for an internal combustion engine according to the present invention. It is an arrow view of the (2)-(2) line cross section of FIG. It is a perspective view of the variable valve mechanism of FIG. It is a disassembled perspective view of the valve lift mechanism of FIG. FIG. 5 is an exploded perspective view showing a relationship between a slider gear and a rocker shaft of the valve lift mechanism of FIG. 4. It is a perspective view which fractures | ruptures and shows the upper half of the valve lift mechanism of FIG. FIG. 3 is a side view used for explaining the operation when the relative phase difference between the input arm and the output arm in FIG. 2 is maximized. FIG. 3 is a side view used for explaining the operation when the relative phase difference between the input arm and the output arm in FIG. 2 is minimized. It is a longitudinal cross-sectional view of the lash adjuster shown in FIG. FIG. 3 is a side view of a single output arm shown in FIG. 2. It is a flowchart used for operation | movement description by the control means shown in FIG. FIG. 8 is a side view corresponding to FIG. 7A, exaggeratingly showing a state when the lash adjuster is pumped up when the intake valve shown in FIG. 2 is opened. It is a side view which shows a mode when the intake valve will be in an incomplete valve closing state due to the pump-up of FIG. It is a side view which shows a mode when dealing with the abnormality of the incomplete valve closing state of FIG. It is a side view which shows the continuation of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 12 Cylinder head 12a Intake port 14 Intake valve 15 Exhaust valve 16 Intake cam shaft 17 Intake cam 24 Rocker arm 24a Roller arm roller 25 Rush adjuster 25b Rush adjuster plunger
3 Variable valve mechanism 31 Rocker shaft 32 Control shaft 33 Actuator (drive means)
4 Valve lift mechanism 41 Input arm (cam striking member)
42A, 42B Output arm (valve striking member)
42d Cam surface of output arm 43 Slider gear 5, 6 Sensor
7 Controller UL Zero lift zone CL Plus lift zone DL Minus lift zone

Claims (7)

As the camshaft cam rotates, the end pivot type rocker arm, one end of which is supported by a hydraulic lash adjuster, is tilted to push the intake and exhaust valves on the other end of the rocker arm and A variable valve mechanism for an internal combustion engine that can change the operating characteristics of at least one of a valve and an exhaust valve,
A control shaft is inserted in the center hole of the rocker shaft fixedly supported on the cylinder head in parallel with the camshaft so as to be axially displaceable, and a slider gear is mounted on the outer periphery of the rocker shaft so as to be interlocked with the control shaft. A cam hitting member and a valve hitting member are externally mounted on a slider gear through a helical spline whose axial direction is adjacent to each other in the axial direction, and the control shaft is displaced in the axial direction so that the valve hitting member with respect to the cam hitting member It is configured to change the relative phase difference of
The valve striking member has a cam surface that comes into contact with the rocker arm, and a negative lift section is provided on the cam surface to allow the other end position of the rocker arm to move from the zero lift position to the non-lift side. A variable valve mechanism for an internal combustion engine. 2. The valve hitting member according to claim 1, wherein the valve striking member has a cylindrical housing, and a projecting piece projecting radially outward is provided at a predetermined circumferential position on the outer periphery of the housing. A skirt that extends in the circumferential direction is provided on the side,
On the outer peripheral surface of the skirt, a base circle that is concentric with the outer periphery of the housing is provided in the projecting piece side region, and the center of the output arm toward the anti-projection piece side direction in the anti-projection piece side region. An inclined curved surface with a gradually decreasing radius dimension is provided,
The cam surface is a region from the protruding end of the protruding piece to the end of the skirt portion, and the valve lift amount is continuously increased or decreased from the protruding end of the protruding piece to the end of the skirt portion. And the base circle of the skirt part is a zero lift section for reducing the valve lift amount to zero, and the inclined curved surface of the skirt part moves the valve in the anti-lift direction. A variable valve mechanism for an internal combustion engine, characterized by being a negative lift section for allowing.   3. When an abnormality that causes the valve to be in an incomplete valve closing state occurs in claim 1 or 2, the valve striking member is moved so that the negative lift section of the cam surface is arranged to face the rocker arm. A variable valve mechanism for an internal combustion engine. As the camshaft cam rotates, the end pivot type rocker arm, one end of which is supported by a hydraulic lash adjuster, is tilted to push the intake and exhaust valves at the other end of the rocker arm, and at least A variable valve mechanism for an internal combustion engine capable of changing the operating characteristics of an intake valve,
A control shaft is inserted in the center hole of the rocker shaft fixedly supported on the cylinder head in parallel with the camshaft so as to be axially displaceable, and a slider gear is mounted on the outer periphery of the rocker shaft so as to be interlocked with the control shaft. A cam hitting member and a valve hitting member are externally mounted on a slider gear through a helical spline whose axial direction is adjacent to each other in the axial direction, and the control shaft is displaced in the axial direction so that the valve hitting member with respect to the cam hitting member It is configured to change the relative phase difference of
A variable valve mechanism for an internal combustion engine, wherein when the exhaust valve is in an incomplete valve closing state, a lift amount of the intake valve by the valve striking member is made smaller than a target. 5. The negative lift according to claim 4, wherein the valve striking member has a cam surface that contacts the rocker arm, and the cam surface allows movement of the other end position of the rocker arm from the zero lift position to the non-lift side. There is a section,
A variable valve mechanism for an internal combustion engine, wherein when the incompletely closed state occurs, the valve striking member is moved so that a minus lift section of a cam surface thereof is opposed to a rocker arm. As the camshaft cam rotates, the end pivot type rocker arm, one end of which is supported by a hydraulic lash adjuster, is tilted to push the intake and exhaust valves on the other end of the rocker arm and A variable valve mechanism for an internal combustion engine that can change the operating characteristics of at least one of a valve and an exhaust valve,
A control shaft is inserted into the center hole of the rocker shaft fixedly supported in parallel to the camshaft on the cylinder head so as to be axially displaceable, and a slider gear is externally mounted on the outer periphery of the rocker shaft so as to be interlocked with the control shaft. The cam hitting member and the valve hitting member are externally mounted on the slider gear via axial splices that are adjacent to each other in the axial direction, and the control shaft is displaced in the axial direction by the driving means as necessary to displace the cam hitting member. It is configured to change the relative phase difference of the valve striking member with respect to the striking member,
An abnormality detection means for detecting an abnormality that causes the valve to be incompletely closed when the valve is closed, and the drive means for reducing the valve lift amount by the valve striking member when the abnormality detection means detects an abnormality. A variable valve mechanism for an internal combustion engine, comprising: coping means for driving the engine.   7. The abnormality detection unit according to claim 6, wherein the abnormality detection unit includes a sensor that detects a position on the other end side of the rocker arm, and a determination unit that determines presence / absence of the abnormality detection based on a detection output of the sensor. A variable valve mechanism for an internal combustion engine.

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