JP4048832B2 - Engine valve gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve operating apparatus for an engine that directly drives a valve via a tappet, and belongs to the technical field of an internal combustion engine of a vehicle.
[0002]
[Prior art]
As a valve operating device that opens and closes intake and exhaust valves provided in engine cylinders, in order to improve fuel efficiency and output, change the opening and closing timing, lift amount, etc. according to the operating state, or low load operation Some of the two intake valves have a hydraulically operated variable valve mechanism that stops one valve. The present applicant also discloses a direct drive variable valve operating apparatus using a tappet that constantly contacts a cam provided on a camshaft to convert the rotation of the cam into a reciprocating motion and transmits this to a valve. The one disclosed in Japanese Patent No. -54413 is proposed. In this valve operating apparatus, a cylindrical tappet is divided into a center tappet at the center and side tappets located on both sides of the center tappet, and a lock mechanism for engaging and disengaging these tappets is provided. The lift amount of the valve is variable depending on whether the valve is lifted by a low lift cam or by a high lift cam via a center tappet and a side tappet engaged by a lock mechanism. Furthermore, by adopting such a configuration, it is possible to reduce the uneven wear of the tappet guide that slidably accommodates the tappet, which has been a problem with the conventional split type tappet, while ensuring the sliding length of the tappet with respect to the cam. Is possible.
[0003]
By the way, in such a valve operating device, it is necessary to determine whether or not the lift characteristics of a valve such as a high lift or a low lift are switched according to the switching command in order to maintain a healthy engine operation. is important. In other words, if the valve lift characteristics do not switch as commanded, the engine status expected from the requested lift characteristics will not match the actual engine status, resulting in failure to obtain a predetermined output. May occur.
[0004]
For example, Japanese Patent Laid-Open No. 3-67009 discloses a valve operating device that can detect a switching failure of a switching mechanism for switching a lift characteristic of a valve. This valve operating apparatus is of a type in which the valve is indirectly driven via a rocker arm pivotally supported by a rocker shaft, and the first to third rocker arms are moved by a lock mechanism having a hydraulically driven piston and the like. Engagement release is possible. That is, the lock mechanism is configured to disengage each rocker arm during low-speed operation of the engine, and to engage the first and third rocker arms and engage the second and third rocker arms during high-speed operation of the engine. Has been. In order to detect a switching failure of the lock mechanism in that case, a position sensor for directly detecting the position of the piston is attached in the vicinity of the lock mechanism. By doing so, the position of the piston is directly detected by the position sensor, and therefore it is possible to reliably determine whether or not the piston is at a predetermined position based on this detection signal, and consequently, the switching failure of the lock mechanism. It has become.
[0005]
Further, as a technique for determining a failure in switching of lift characteristics in a valve gear of the same type that indirectly drives a valve via a rocker arm, it is provided in a cylinder as disclosed in JP-A-7-233742. Based on the in-cylinder pressure detected by the in-cylinder pressure sensor, as disclosed in Japanese Patent Laid-Open No. 5-79363, or to detect malfunction of a hydraulic control system such as a solenoid valve for switching, As disclosed in JP-A-317208, there are those based on the hydraulic pressure supplied to the switching mechanism.
[0006]
Further, as a technique for determining an abnormality in a variable valve timing device of a type that changes the phase of the camshaft with respect to the crankshaft, as disclosed in JP-A-5-106472, a valve overlap between an intake valve and an exhaust valve There are those based on the vibration state of the engine detected by the knock sensor, and those based on the amount of change in the intake air amount as disclosed in JP-A-8-326516.
[0007]
[Problems to be solved by the invention]
By the way, in the engine provided with the three-division type tappet disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2002-54413, hydraulic pressure is applied so that the center tappet in the disengaged state and the side tappets on both sides are engaged to operate the engine at high speed. When there is an operation command for a lock mechanism having a plunger or a lock pin that is driven and moved, if there is a switching failure in which the center tappet and both side tappets do not engage, the center tappet is The center tappet is in a free state only supported by a spring that biases the center tappet toward the high lift cam. In that case, since the high lift cam arranged corresponding to the center tappet is driven to rotate at a high speed, the center tappet is pushed by the high nose portion of the high lift cam so as to be repelled inward of both side tappets, The center tappet may be moved down impactively and may once separate from the high lift cam without following the operation of the high lift cam. The center tappet that has moved down then moves upward so as to be repelled, and collides with the high lift cam that has been separated during the downward movement.
[0008]
If the lock mechanism does not operate as instructed in this way, the engine state expected from the requested lift characteristics and the actual engine state do not match as described above, and a predetermined output cannot be obtained. Arise.
[0009]
Further, if the shocking vertical movement of the center tappet continues, the center tappet and the high lift cam may be damaged due to a collision, or the spring may be damaged due to excessive compression.
[0010]
It is possible to use a spring with a large urging force so that the center tappet is always in contact with the high lift cam even in the case of the switching failure of the locking mechanism described above. This measure cannot be preferred because the pushing force when the free center tappet is pushed into the inner side of both side tappets due to the cams being separated from the both side tappets increases the energy loss of the engine. For this reason, the biasing force of the spring is usually set so that the free center tappet can follow the high lift cam and does not cause a large energy loss of the engine.
[0011]
In other words, it is important to determine whether or not the lock mechanism is operating normally according to the operating state of the engine and to detect it early if there is an abnormality in operation. For example, the position sensor described in Japanese Patent Laid-Open No. 3-67009 is applied to the valve operating apparatus, and a method of directly detecting the movement of the plunger or the lock pin provided in the lock mechanism is considered preferable. In that case, the sensor must be installed in a limited space in the cylinder head so as to be able to follow the tappet that reciprocates while the lock mechanism is accommodated. There's a problem.
[0012]
Therefore, in view of the above problem in the valve operating device of the engine in which the valve is directly driven through the tappet divided so as to be freely disengageable, the present invention eliminates the malfunction of the lock mechanism that engages and disengages these tappets. It is an object to enable determination.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is configured as follows.
[0014]
First, the invention described in claim 1 includes a cylindrical tappet that is slidably received in a guide hole provided in a cylinder head, and a camshaft that includes a cam that drives a valve via the tappet. The tappet is divided into a first tappet and a second tappet, a lock mechanism that engages and disengages the first tappet and the second tappet, and a spring that biases the first tappet toward the cam. And a control means for controlling the operation of the lock mechanism in accordance with the operating state of the engine, and the camshaft includes first and second tappets corresponding to the first and second tappets, respectively. A cam and a second cam having a smaller lift amount than the first cam, and when the first tappet and the second tappet are in the disengaged state, the second cam and the valve are connected via the second tappet. On the other hand, when the first tappet and the second tappet are in the engaged state, the valve operating device for the engine configured to connect the first cam and the valve via the first tappet and the second tappet. In an operation state in which the vibration detecting means for detecting vibration due to the collision between the first cam and the first tappet and the lock mechanism are controlled to engage the first tappet and the second tappet, Switching failure determination means for determining a switching failure from the disengaged state of the first tappet and the second tappet to the engaged state by the lock mechanism based on the detection signal from the detecting means is provided.
[0015]
According to the present invention, the switching failure can be determined by detecting vibration. Therefore, it is possible to detect an abnormality at an early stage, and it is possible to quickly avoid problems such as the engine state expected from the requested lift characteristics and the actual engine state becoming inconsistent.
[0016]
Further, if the shocking vertical movement of the first tappet continues at the time of switching failure, the first tappet and the first cam may be damaged due to a collision, or the spring may be damaged due to excessive compression. According to the present invention, since an abnormality is sensed at an early stage, these concerns can be avoided.
[0017]
Note that the second cam includes a cam whose profile is a perfect circle.
[0018]
Next, the invention according to claim 2 is characterized in that in the engine valve operating apparatus according to claim 1, the vibration detecting means detects vibration of the camshaft.
[0019]
According to the present invention, since the vibration of the camshaft, in which the vibration due to the collision between the first tappet and the first cam at the time of switching failure is easily transmitted, is detected, the switching failure determination accuracy is improved.
[0020]
According to a third aspect of the present invention, in the engine valve operating device according to the second aspect, the vibration detecting means is attached to a cam cap that supports the camshaft.
[0021]
Although it is difficult to directly attach the vibration detecting means to the camshaft that is rotationally driven, it is easy to attach the camshaft to the cam cap that directly supports the camshaft. Can be reliably detected with a simple configuration.
[0022]
According to a fourth aspect of the present invention, in the engine valve operating apparatus according to the third aspect, the first cam provided in the vicinity of the detection means has a predetermined timing when the vibration is detected by the vibration detection means. It is set at the time when it is located in the cam angle range.
[0023]
If a collision occurs between the first tappet and the first cam, the arrangement position of the first cam, that is, the cam angle at that time, is generally limited to a predetermined range. Therefore, according to the present invention, since the vibration is detected by paying attention to the predetermined cam angle range where the collision is assumed to occur, the collision between the first tappet and the first cam that moves up impactively is detected. The resulting camshaft vibration can be reliably detected, and the determination accuracy of switching failure is improved.
[0024]
Further, since the cam angle of the first cam is set for each cylinder, the cylinder in which the switching failure has occurred can be identified based on the cam angle in which vibration is detected, and the repair work can be speeded up. .
[0025]
According to a fifth aspect of the present invention, in the valve operating apparatus for an engine according to the second aspect, the lock mechanism is operated by the hydraulic pressure supplied via the hydraulic control valve and detects the hydraulic pressure. The switching failure determination means determines switching failure based on the hydraulic pressure detected by the hydraulic pressure detection means and the detection signal from the vibration detection means when the lock mechanism operation command is issued.
[0026]
According to this invention, after eliminating the failure factor on the hydraulic control system side based on the hydraulic pressure detected by the hydraulic pressure detection means for detecting the hydraulic pressure supplied to the lock mechanism, based on the detection signal from the vibration detection means. Since the switching failure in the lock mechanism can be determined, the determination accuracy of the switching failure is improved. That is, when the hydraulic control valve operates normally in response to an operation command to the lock mechanism, hydraulic pressure that enables switching from disengagement of the lock mechanism to engagement is supplied. Usually, the hydraulic pressure at this time is high. Therefore, by detecting the oil pressure by the oil pressure detecting means, for example, when the oil pressure is high and vibration is detected, there is a problem on the lock mechanism side, whereas when the oil pressure is low and vibration is detected, the oil pressure control system side is detected. Since it can be determined that there is a problem, the determination accuracy of the switching failure in the lock mechanism is improved.
[0027]
According to a sixth aspect of the present invention, in the valve operating apparatus for an engine according to the second aspect of the present invention, an intake air amount detecting means for detecting an intake air amount is provided, and the switching failure determining means is provided at the time of operating the lock mechanism. Switching failure is determined based on a deviation between the actual intake air amount detected by the intake air amount detecting means and the set intake air amount and a detection signal from the vibration detecting means.
[0028]
In general, even in the operation region where the engine speed is relatively low, even if a collision between the first tappet and the first cam occurs due to poor switching, the collision in that case is slight. It is difficult to detect shaft vibration. That is, there is a limit to the determination of switching failure based on the vibration detection means.
[0029]
On the other hand, if the lift characteristics of the intake valve switch normally from low lift to high lift or from high lift to low lift, the intake air amount changes accordingly, so this intake air amount is detected as an air flow sensor. By detecting with the means, it is possible to determine the failure of switching from disengagement to engagement or from engagement to disengagement in the lock mechanism. However, when a single airflow sensor is provided in a multi-cylinder engine, if switching failure occurs in only some of the cylinders, abnormalities are averaged by other normal cylinders, and switching failure is accurately determined. You may not be able to. As a solution for this, an air flow sensor may be provided for each cylinder, but this is disadvantageous in terms of cost.
[0030]
In addition, in order to accurately determine the switching failure, for example, a precise map of the intake air amount that is organized by various throttle openings and engine speeds is required as the intake air amount serving as a determination criterion. In that case, in order to store this enormous map, a considerable part of the memory of the control unit that performs various controls on the engine is occupied, which causes a problem in terms of load of the control unit. As a solution, it is possible to reduce the memory problem by forcing the engine operating state to a predetermined state and detecting the intake air amount at that time. The predetermined state is problematic from the point of maintaining healthy engine operation. On the other hand, waiting for an opportunity to realize the predetermined state is not reasonable due to its uncertainty.
[0031]
On the other hand, according to the present invention, it is possible to employ the determination of the switching failure based on the intake air amount and the determination of the switching failure based on the detection signal from the vibration detection means according to the engine speed. It is possible to simplify the configuration and require less memory to store this map, and determine switching failure in a wide engine operating range from a relatively low engine speed to a relatively high engine speed. Is possible.
[0032]
In addition, based on the vibration detected by the vibration detecting means, even when a switching failure occurs in some cylinders and the deviation of the intake air amount is small, this switching failure can be reliably determined.
[0033]
Further, based on the intake air amount detected by the intake air amount detection means, it is possible to determine the failure of switching from engagement to disengagement in addition to the failure to switch from disengagement to engagement in the lock mechanism.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an engine valve gear according to an embodiment of the present invention will be described.
[0035]
[Schematic configuration of the engine]
As shown in FIGS. 1 and 2, the engine includes four cylinders A <b> 1 to A <b> 4 and a cylinder block 1, a cylinder head 2, and a cylinder head cover 3. Then, for each cylinder A1 to A4, two intake ports (only one is shown in FIG. 1) Pin, Pin and intake valves 11, 11, and two exhaust ports (also only one is shown) Pex, Pex and exhaust valve 12 , 12 are provided, and four tappets (only two are shown in FIG. 1) 13... 13 are provided for each of the cylinders A1 to A4.
[0036]
Further, this engine has three cams 16, 16, and 17 with different profiles formed on the intake and exhaust cam shafts 14 and 15 for each tappet 13, respectively (two cams 16 and 17 in FIG. 1). Is a variable valve engine.
[0037]
[cylinder head]
The cylinder head 2 includes a cylinder head base portion 20 and side wall portions 21, 22, and 23 erected from the base portion 20. The cylinder head base 20 is a portion where intake ports Pin and Pin and exhaust ports Pex and Pex that face the combustion chamber B are formed, and a fuel injection valve, intake and exhaust manifolds, etc. (not shown) are assembled. The cylinder head 2 is assembled to the cylinder block 1 by a head bolt (not shown) that penetrates the cylinder head base 20 and enters the cylinder block 1.
[0038]
A support member 30 is provided at the base 20 of the cylinder head 2. The support member 30 extends horizontally in a space surrounded by the side wall portions 21 to 23 of the cylinder head 2, and includes vertical wall portions 31... 31 for bearing lower portions of the intake and exhaust camshafts 14 and 15, and a tappet. And tappet guides 32... 32 that slidably accommodate 13. Cam caps 33... 33 for bearing upper portions of the intake and exhaust camshafts 14 and 15 are coupled to upper surfaces of the vertical wall portions 31... 31 by bolts 34. Thereby, bearing portions 35... 35 for bearing the camshafts 14 and 15 are configured. The bolts 34a... 34a penetrate the vertical wall portions 31... 31 and enter the cylinder head base 20 to connect the cam caps 33... 33 to the vertical wall portions 31. It is tightened together.
[0039]
Further, the left and right sides of the supporting member 30 in the drawing are assembled to the cylinder head 2 by bolts 36... 36 at three locations.
[0040]
Further, the support member 30 has tappets 13... 13 in close proximity to the tappet guides 32... 32 of the cylinders A1 to A4 on both sides of the intake system side and the exhaust system side, parallel to the intake and exhaust camshafts 14 and 15. Oil galleries 37 and 38 for supplying hydraulic pressure to are formed. An oil pressure sensor 39 for detecting the working oil pressure is interposed on the right side of the oil gallery 38 in the figure.
[0041]
The support member 30 is formed with cylindrical spark plug attachment portions 40... 40 having holes through which spark plugs (not shown) for the respective cylinders A1 to A4 are inserted. The spark plug mounting portion 40 on the left side in the example is formed in a columnar two-circle connection shape integrally with a mounting portion for mounting a hydraulic control valve 41 for controlling a hydraulic pressure supplied to a lock mechanism described later. .
[0042]
Then, vibrations of the camshafts 14 and 15 which are characteristic portions of the present invention are detected on the upper surfaces of the cam caps 33 and 33 in the bearing portions 35 and 35 on the intake system side and the exhaust system side which are located in the middle in the left-right direction. Vibration sensors 42 and 42 are attached to the cam caps 33 and 33 through protrusions 33a and 33a formed integrally with the cam caps 33 and 33, respectively. Although one vibration sensor 42 is attached to each of the intake system side and the exhaust system side, the number thereof can be increased or decreased as appropriate.
[0043]
[cam]
Of the three cams 16, 16, 17 having different profiles, the low lift cams 16, 16 corresponding to the second cam described in the claims have the same profile, and are also designated as the first cam. The corresponding central high-lift cam 17 has a profile different from that of the cams 16 and 16. That is, the low lift cams 16, 16 at both ends provide a small lift amount, and the central high lift cam 17 provides a large lift amount.
[0044]
Instead of the low lift cam 16, an extremely low lift cam (providing a lift amount of about 1 to 2 mm) having a substantially circular profile can be used. This is because when a fuel injection valve is provided in the intake ports Pin, Pin and port injection is executed, if a low lift cam 16 having a perfect circular profile is used, the valve is completely stopped. As a result, fuel accumulates in the intake ports Pin and Pin, and the fuel is sucked into the combustion chamber B at a time when the fuel is switched to the high lift cam 17 next time. In order to avoid such a problem, the ultra-low lift cam is used. Therefore, in a direct injection engine, a complete valve may be stopped by using a cam whose profile is a perfect circle and a substantial lift amount is zero.
[0045]
[Tuppet]
The stem end 51 of the intake valve 11 or the exhaust valve 12 is in contact with the lower portion of the substantially cylindrical tappet 13. The stem end 51 is provided with a spring receiver 53 that receives a valve spring 52 interposed between the stem end 51 and the cylinder head base 20. The valve spring 52 urges the intake valve 11 or the exhaust valve 12 in the direction in which the intake port Pin or the exhaust port Pex is closed, respectively.
[0046]
As shown in FIG. 3, the tappet 13 accommodated in the tappet guide 32 is configured such that the flat surface 54 a in contact with the high lift cam 17 has a long side in the sliding direction of the cam 17 indicated by an arrow a. The center tappet 54 and the flat surfaces 55a and 55a that contact the low lift cams 16 and 16 are configured to have long sides in the sliding direction of the cams 16 and 16 indicated by the arrow a so as to sandwich the center tappet 54. The side tappets 55 and 55 are thus divided into three. In this case, the center tappet 54 and the side tappets 55 and 55 are nothing but the first tappet and the second tappet described in the claims.
[0047]
Hereinafter, as an example, the configuration of the tappet 13 corresponding to one intake port Pin will be described in detail with reference to FIGS.
[0048]
<Center tappet>
As shown in FIGS. 4, 6, and 7, the center tappet 54 has a substantially rectangular flat surface 54 a that is in contact with the high lift cam 17 provided on the intake cam shaft 14. It is formed along the sliding direction. Further, the center tappet 54 has two outer surfaces 54b, 54b extending downward from an edge portion along the cam sliding direction of the flat surface 54a, and two circles extending downward from both ends of the flat surface 54a in the cam sliding direction. Arc-shaped outer peripheral surfaces 54c and 54c are formed.
[0049]
Further, extending portions 54d... 54d extending in the direction of the site tappets 55 and 55 are formed on both sides of the outer peripheral surfaces 54c and 54c of the center tappet 54. The extending portions 54d. , 55 are formed in sliding contact with each other. In addition, relatively shallow recesses 54f... 54f are provided at the base end portions of the extending portions 54d.
[0050]
Further, on the back side of the flat surface 54a of the center tappet 54, a protruding portion 54g extending downward is formed so as to be orthogonal to the cam sliding direction, that is, parallel to the intake camshaft 14, and the protruding portion 54g includes A lock hole 54h is formed so as to penetrate this. A pair of spring seats 54i and 54i (only one is shown in FIG. 6) are formed on the back side of the flat surface 54a so as to sandwich the protruding portion 54g.
[0051]
<Side tappet>
As shown in FIGS. 5 to 7, the side tappets 55, 55 have two flat surfaces 55 a, 55 a that are in contact with the low lift cams 16, 16 provided on the intake camshaft 14. 16 and 16 are formed along the sliding direction. Further, the side tappets 55 and 55 include two inner side surfaces 55b and 55b extending downward from edges along the cam sliding direction of the flat surfaces 55a and 55a, and both end portions of the flat surfaces 55a and 55a in the intake camshaft 14 direction. Two substantially arc-shaped outer peripheral surfaces 55c and 55c extending downward from the outer periphery are formed.
[0052]
And both side tappets 55 and 55 are connected in the lower position, and a connecting portion 55d that provides a contact portion with the stem end 51 is formed. A pair of pulling seats 55e and 55e are formed in the vicinity of both ends along the cam sliding direction of the connecting portion 55d.
[0053]
The side tappets 55, 55 are formed with protrusions 55f... 55f extending in the direction of the center tappet 54 from both end portions of the inner side surfaces 55b, 55b in the cam sliding direction in a non-contact state with the center tappet 54. The protrusions 55f to 55f are provided so as to correspond to the recesses 54f to 54f of the center tappet 54.
[0054]
Further, the side tappets 55, 55 are slidable contact surfaces that extend downward from both ends of the flat surfaces 55a, 55a in the cam sliding direction, that is, the protruding portions 55f ... 55f, and slidably contact the receiving surfaces 54e ... 54e of the center tappet 54. 55g ... 55g is formed.
[0055]
Further, the side tappets 55 and 55 are formed with lock holes 55h and 55h that pass through the axis of the tappet 13 and are parallel to the intake camshaft 14 so as to pass from one outer peripheral surface 55c to the other outer peripheral surface 55c. ing. These lock holes 55h, 55h communicate with the lock hole 54h of the center tappet 54 in a straight line when the flat surface 54a of the center tappet 54 and the flat surfaces 55a, 55a of the side tappet 55, 55 are flush with each other. Is formed.
[0056]
Further, the center tappet 54 is urged toward the high lift cam 17 between the pair of spring seats 55e, 55e on the side tappet 55, 55 side and the pair of spring seats 54i, 54i on the center tappet 54 side. A pair of springs 56, 56 are interposed. In this case, the upper ends of the springs 56 and 56 are disposed so as to overlap with a protruding portion 54g provided on the center tappet 54 in a side view. The urging force of the springs 56, 56 is set to such an extent that the free center tappet 54 can follow the high lift cam 17 and does not cause a large energy loss of the engine. Yes.
[0057]
The connecting portion 55d is provided with a rib 55i that gives rigidity to the connecting portion 55d over both side tappets 55, 55, and a protruding portion 55i 'is provided at an intermediate portion of the rib 55i. In this case, the distance between the protrusion 55i ′ and the protrusion 54g of the center tappet 54 is set such that the springs 56 and 56 are not damaged when the protrusions 54g and 55i ′ come into contact with each other. Yes.
[0058]
By doing so, the center tappet 54 is incorporated between the side tappets 55, 55, and the outer peripheral surfaces 54c, 54c, 55c, 55c of these tappets 54, 55, 55 and the tappet guide 32 can slide. The receiving surfaces 54e ... 54e of the center tappet 54 and the sliding contact surfaces 55g ... 55g of the side tappets 55, 55 can slide. The center tappet 54 is incorporated in the side tappets 55 and 55 with springs 56 and 56 interposed therebetween, and can be moved relative to the side tappets 55 and 55 against the urging force of the springs 56 and 56. Become.
[0059]
<Lock mechanism>
A lock mechanism that engages and disengages the center tappet 54 incorporated so as to be movable relative to the side tappets 55 and 55 and the side tappets 55 and 55 connected to the stem end 51 of the intake valve 11 will be described with reference to FIGS. 7 will be described.
[0060]
As described above, the lock hole 54h of the center tappet 54 and the lock holes 55h and 55h of the side tappets 55 and 55 are in a state where the flat surface 54a of the center tappet 54 and the flat surfaces 55a and 55a of the side tappets 55 and 55 are flush with each other. At this time, it communicates in a straight line in the direction of the intake camshaft 14.
[0061]
A plunger 57 that advances into the lock hole 54h of the center tappet 54 by hydraulic pressure is inserted into the lock hole 55h of one side tappet 55, and the other side tappet 55 is pushed into the lock hole 54h of the center tappet 54 by the plunger 57. The lock pin 58 that advances into the lock hole 55h of the lock pin 58 is provided around the lock pin 58 through a flange portion 58a provided near the plunger 57 of the lock pin 58, and the lock pin 58 is always on the plunger 57 side. Each of the springs 59 for biasing is arranged.
[0062]
Bushes 60 and 61 are inserted and fixed in the vicinity of both ends of the lock pin 58 in the lock hole 54 h of the center tappet 54. Of the bushes 60 and 61, the bush 60 closer to the plunger 57 abuts on the flange portion 58 a of the lock pin 58 and restricts the movement of the lock pin 58 toward the plunger 57 beyond the outer surface 54 b of the center tappet 54. . The other bush 61 compresses and holds the spring 59 between the flange portion 58a.
[0063]
Further, separate bushes 62 and 63 are inserted and fixed in the lock holes 55h and 55h of the both side tappets 55 and 55, respectively. The bush 62 on the plunger 57 side of the bushes 62 and 63 is configured to open facing the lock pin 58, and the plunger 57 is slidably fitted inward. The other bush 63 accommodates the tip end portion of the lock pin 58 that enters, and has a stopper portion 63 a that restricts the lock pin 58 from entering a predetermined length or more.
[0064]
The ends 62a and 63b of the bushes 62 and 63 on the center tappet 54 side are formed in gaps G and G between the outer surfaces 54b and 54b of the center tappet 54 and the inner surfaces 55b and 55b of the side tappets 55 and 55, respectively. Each is arranged so as to protrude by a predetermined length.
[0065]
Thus, the lock holes 54h, 55h, 55h, the plunger 57, the lock pin 58, the spring 59 and the like constitute a lock mechanism.
[0066]
<Tuppet detent mechanism>
As shown in FIGS. 6 and 7, in the tappet 13, a ball member 64 is supported so as to partially protrude from a ball support portion 63 c provided on the outer peripheral side of the tappet 13 of the bush 63. A guide groove 32 a is formed on the sliding surface of the 32 tappets 13 so as to be able to engage with the ball member 64 along the sliding direction of the tappet 13.
[0067]
By doing so, the rotation around the axis of the tappet 13 in the tappet guide 32 is regulated through the engagement between the ball member 64 and the guide groove 32a. As a result, a good sliding positional relationship between the tappet 13, that is, the center tappet 54 and the side tappets 55, 55, and the cams 16, 16, 17 is maintained.
[0068]
<Tappet upward slip prevention mechanism>
As described above, the end portions 62a and 63b on the center tappet 54 side of the bushes 62 and 63 fixed to the lock holes 55h and 55h of the side tappets 55 and 55 protrude so as to protrude to the center tappet 54 side by a predetermined length. Has been placed. On the other hand, as shown in FIGS. 4, 6, and 7, the outer surfaces 54b, 54b of the center tappet 54 have contact surfaces 54j ′, which are concave arcuate circumferential surfaces around the lock holes 54h, 54h. Abutting portions 54j and 54j having 54j 'are projected in a predetermined length in both side tappets 55 and 55 directions.
[0069]
The center tappet 54 is always urged upward by the springs 56, 56, but with the above-described configuration, the contact surfaces 54 j ′, 54 j ′ on the center tappet 54 side and the side tappet 55 When the end portions 62a, 63b of the bushes 62, 63 on the 55 side are engaged, the upward withdrawal of the center tappet 54 from the tappet 13 is restricted. In the above configuration, there is nothing that restricts the downward movement of the center tappet 54 relative to the side tappets 55, 55, so that the center tappet 54 is subjected to the urging force of the springs 56, 56 in the unlocked state as will be described later. It can move down.
[0070]
<Oil receiving recess for tappet lubrication>
As shown in FIGS. 1 and 3, the tappet guide 32 and the tappet 13 are provided with lubricating oil in portions along the cam sliding direction around the opening on the cams 16, 16, and 17 side of the tappet guide 32. Oil receiving recesses 32b, 32b, 32c,... 32c that are supplied to the sliding surfaces of the center tappet 54 and the side tappets 55, 55 are provided. These oil receiving recesses 32b, 32b, 32c... 32c are provided so as to be inclined downward on the tappet 13 side.
[0071]
By doing so, it is possible to satisfactorily supply the lubricating oil to the sliding surface between the tappet guide 32 and the tappet 13 and to efficiently collect the lubricating oil with a simplified configuration.
[0072]
[Supplying hydraulic pressure to tappet]
As shown in FIGS. 1 and 2, the oil gallery 37 is supplied so that the hydraulic pressure from the oil gallery 37, 38 extending in the longitudinal direction of the cylinder head 2, that is, in the direction of the camshafts 14, 15 is supplied to the lock mechanism of each tappet 13. , 38 and branch oil passages 37a... 37a, 38a... 38a are provided respectively that are branched from the tappet guides 32.
[0073]
As an example, the opening in the inner peripheral surface of the tappet guide 32 of the branch oil passage 37a is in a state where the flat surfaces 55a, 55a of the side tappets 55, 55 are in contact with the base circle portions of the low lift cams 16, 16. As shown in FIG. 7, it communicates with an oil passage 71 provided in one side tappet 55. The side tappet 55 includes an oil passage 72 that communicates with the oil passage 71 and an oil passage 73 that communicates the oil passage 72 and the space 62 c behind the plunger 57 via an opening 62 b formed in the bush 62. Is provided.
[0074]
Further, as shown in FIG. 2, the support member 30 includes an inflow oil passage 74 for introducing hydraulic pressure from an oil pump (not shown), that is, a hydraulic power source, to the hydraulic pressure control valve 41, and hydraulic pressure from the hydraulic pressure control valve 41. An spilled oil passage 75 for supplying oil gallery 37, 38 is provided.
[0075]
By doing so, the hydraulic pressure for operating the plunger 57 in the lock mechanism of the tappet 13 is controlled by the hydraulic control valve 41, and the space 62c is set via the branch oil passage 37a during high-speed operation of the engine that locks the lock mechanism. To be supplied. That is, the operating hydraulic pressure is introduced into the hydraulic control valve 41 through the inflow oil passage 74. When the hydraulic control valve 41 is turned on, the hydraulic pressure is led from the hydraulic control valve 41 through the outflow oil passage 75 to the oil gallery 37, and the side The flat surfaces 55a and 55a of the tappets 55 and 55 are in contact with the base circle portion of the low lift cams 16 and 16, and the opening on the inner peripheral surface of the tappet guide 32 of the branch oil passage 37a communicates with the oil passage 71 of the side tappet 55. In this state, the oil is introduced into the oil passage 71 through the branch oil passage 37a, and is supplied from the oil passage 71 through the oil passage 72 and the oil passage 73 to the space 62c behind the plunger 57 through the opening 62b of the bush 62. On the other hand, when the hydraulic control valve 41 is turned off, the operating hydraulic pressure is released from the space 62c.
[0076]
[Control system]
As shown in FIG. 8, a control unit 80 that performs various controls on the engine includes a water temperature sensor 81 that detects the engine water temperature, an engine rotation sensor 82 that detects the engine speed, and the cranks of the intake and exhaust camshafts 14 and 15. Cam angle sensors (only one is shown in the figure) 83, 83 for detecting the phase angle with respect to the shaft, an air flow sensor 84 for detecting the amount of air taken into the engine, that is, the amount of intake air disposed in the intake passage, 15, vibration sensors 42, 42 that detect vibrations 15, and a hydraulic sensor 39 that is provided in the oil gallery 38 and that detects hydraulic pressure supplied to the lock mechanism are input. A control signal for controlling the operation is output.
[0077]
Then, the control unit 80 stores in the memory, for example, an intake air amount map organized by throttle opening and engine speed.
[0078]
[Operation example of tappet]
Next, as an example, an operation example of the tappet 13 on the intake system side will be described.
[0079]
<Normal operation>
First, when the intake valve 11 is lifted by the low lift cams 16, 16 in order to operate the engine at a low speed, the hydraulic control valve 41 is turned off to release the hydraulic pressure for the space 62 c behind the plunger 57, While being accommodated in the bush 62, the lock pin 58 is positioned in the lock hole 54h through the contact between the flange portion 58a of the lock pin 58 and the bush 60 by the urging force of the spring 59.
[0080]
By doing so, the unlocking state of the locking mechanism is realized, the center tappet 54 and the side tappets 55 and 55 are separated, and the center tappet 54 can move relative to the side tappets 55 and 55. . That is, as shown in FIG. 9, low lift cams 16 and 16 provided on the intake camshaft 14 and rotating in the direction of the arrow b (only one is shown in the figure) are flat surfaces 55a and 55a of both side tappets 55 and 55, respectively. As a result of pushing down the side tappets 55, 55 in the direction of the arrow c, respectively, the intake valve 11 can be lifted low via the stem end 51. On the other hand, the center tappet 54 is highly lifted against the urging force of the springs 56, 56 interposed between the center tappet 54 and both side tappets 55, 55 regardless of the operation of both side tappets 55, 55. The flat surface 54a is pushed by the cam 17 and pushed down in the direction of the arrow c.
[0081]
In this case, as shown in FIGS. 3 to 7, the tappet 13 is divided into a center tappet 54 and side tappets 55 and 55 located on both sides thereof, and outer peripheral surfaces 54 c and 54 c of the center tappet 54 in the cam sliding direction. Since the extended portions 54d... 54d extending on both sides so as to overlap the outer peripheral surfaces 55c and 55c of the side tappets 55 and 55 are provided on both sides, the force for pressing the side tappets 55 and 55 against the tappet guide 32 is applied to the extended portions 54d. 54d, that is, the center tappet 54 is dispersed through the receiving surfaces 54e 54e. Therefore, while ensuring the sliding length of the cams 16, 16, and 17, it is possible to improve the wear resistance by reducing the uneven wear between the tappet 13 and the tappet guide 32 as in the prior art.
[0082]
In addition, since a pair of springs 56 and 56 for urging the center tappet 54 toward the high lift cam 17 are provided on both sides of the lock mechanism for engaging and releasing the center tappet 54 and the side tappets 55 and 55. The amount of relative movement of the center tappet 54 with respect to the side tappets 55 and 55, and thus the lift amount of the intake valve 11 can be set larger.
[0083]
Next, when the intake valve 11 is lifted by the high lift cam 17 in order to operate the engine at a high speed, when the hydraulic pressure control valve 41 is turned on and the operating hydraulic pressure is supplied to the space 62 c at the back of the plunger 57, the plunger 57 advances and locks. The pin 58 is moved toward the bush 63 against the urging force of the spring 59, and the movement of the lock pin 58 is restricted when the tip of the lock pin 58 comes into contact with the stopper portion 63a of the bush 63.
[0084]
By doing so, one side tappet 55 and the center tappet 54 are connected through engagement of the plunger 57 and the bush 60 in the lock hole 54h, and at the same time, the center tappet 54 and the other side tappet 55 are connected to the lock pin. 58 and the bush 63 in the lock hole 55h are connected to each other, and the center tappet 54 and both side tappets 55, 55 are locked. In this state, as shown in FIG. 10, the high lift cam 17 that rotates at high speed in the direction of arrow b presses the flat surface 54 a of the center tappet 54, thereby connecting the connected center tappet 54 and both side tappets 55, 55. Can move together in the direction of arrow c, and can lift the intake valve 11 through the stem end 51.
[0085]
<Abnormal operation>
By the way, if the switching failure from the disengaged state of the center tappet 54 and the both side tappets 55, 55 due to the locking mechanism to the engaged state occurs, the center tappet 54 is located inside the both side tappets 55, 55 as shown in FIG. It is pushed in the direction of the arrow c so as to be struck by the high nose portion of the high lift cam 17 that enters the free state and rotates at a high speed in the direction of the arrow b. That is, the center tappet 54 is shockedly lowered and its flat surface 54a is once separated from the high lift cam 17, and the springs 56 and 56 for supporting the center tappet 54 are greatly compressed as compared with the normal operation shown in FIG. Is done. In this case, before the springs 56 and 56 are compressed so as to be damaged, the projecting portion 54g of the center tappet 54 and the projecting portion 55i ′ provided on the connecting portion 55d of the side tappet 55 and 55 are brought into contact with each other. Since the protrusion 55i ′ is provided, the springs 56 and 56 can be prevented from being damaged.
[0086]
The center tappet 54 that has been moved down in an impact comes into contact with the protruding portion 55i ′ of the side tappet 55, 55 via the protruding portion 54g, and then moves upward so as to be repelled in the direction of the arrow d of the chain line, as indicated by the chain line. It collides with the high lift cam 17 via the flat surface 54a. At this time, vibration of the intake camshaft 14 on which the high lift cam 17 is formed occurs. That is, the collision occurs in a predetermined lift amount range in which negative acceleration occurs in the lift amount change, that is, a predetermined cam angle range, as shown in FIG. From this cam angle range as a vibration detection target range, the vibration sensor 42 attached to the upper surface of the cam cap 33 that supports the intake camshaft 14 in cooperation with the vertical wall portion 31 within the range. By detecting the vibration, it can be accurately determined that the above-described collision has occurred, that is, a switching failure in the lock mechanism has occurred.
[0087]
In addition, since the vibration sensor 42 is attached to the cam cap 33 that supports the intake camshaft 14 from above, which easily transmits vibration due to the collision between the center tappet 54 and the high lift cam 17 when switching is poor, the above-described vibration is simplified. Moreover, it can be reliably detected.
[0088]
During the vertical movement of the center tappet 54, the side tappets 55 and 55 are in contact with the low lift cams 16 and 16 through the flat surfaces 55a and 55a.
[0089]
[Judgment example of switching failure in lock mechanism]
Next, an example of determining a switching failure in the lock mechanism executed by the control unit 80 will be described based on the flowchart shown in FIG.
[0090]
For example, when the engine is in a low speed operation state by the low lift cam 16, the control unit 80 determines whether or not the water temperature by the water temperature sensor 81 exceeds 60 ° C. in step S1, and if NO, in step S2. Then, it waits for the engine rotation speed Ne by the engine rotation sensor 82 to reach the predetermined value Ne1, and in step S3, the hydraulic control valve 41 is turned on to instruct the tappet 13 to perform a high lift operation. That is, the lock mechanism is operated so that the center tappet 54 and the side tappets 55 and 55 are switched from the previous disengaged state to the engaged state.
[0091]
In this case, if the lock mechanism operates normally, the center tappet 54 and the side tappets 55 and 55 are locked, and the tappet 13 operates as shown in FIG. On the other hand, if the lock mechanism does not operate normally, the center tappet 54 exhibits an abnormal operation as described with reference to FIG.
[0092]
Next, in step S4, whether or not the oil pressure P by the oil pressure sensor 39 provided in the oil gallery 38 exceeds a predetermined value P1 set based on the oil pressure expected when the oil pressure control valve 41 is turned on. If YES, it means that the hydraulic control valve 41 operates normally and the predetermined hydraulic pressure is supplied to the oil gallery 38 and therefore to the oil gallery 37. Next, in step S5, the air flow is performed. Whether or not the deviation between the intake air amount by the sensor 84, that is, the actual intake air amount Q, and the set intake air amount Q1 set in the intake air amount map organized by, for example, the throttle opening and the engine speed Ne is smaller than a predetermined value ΔQ. Determine whether. That is, it is determined whether or not the lift amount of the intake valve 11 is increased due to the operation of the lock mechanism as instructed by the control unit 80, and the actual intake amount Q has reached the set intake amount Q1 within an allowable range.
[0093]
If YES in step S5, the actual intake air amount Q is a value commensurate with the set intake air amount Q1, and in this case, in step S6, the engine speed Ne2 is higher than the predetermined value Ne1. Then, it is determined whether or not a vibration detection signal from the vibration sensor 42 is input in a predetermined cam angle range. If NO, that is, if it is determined that the switching has been normally performed, in step S7, the engine speed Ne2 or higher. The high speed operation at the engine speed Ne is allowed.
[0094]
On the other hand, if “YES” in the step S1, the high speed operation of the engine is prohibited, that is, the operation state is limited to the operation by the low lift cam 16 in a step S8.
[0095]
If NO in step S4, it is determined that there is an abnormality in the hydraulic control valve 41. If NO in step S5, it is determined that the actual intake amount Q does not increase because of a switching failure in the lock mechanism. If YES in step S6, it is determined that the vibration is detected because there is a switching failure in the lock mechanism. In any case, in step S9, the warning lamp is turned on and the conventional high-speed operation is performed. Control to switch from low to low speed operation.
[0096]
As described above, since the switching failure in the lock mechanism is determined and the operation state is quickly set to the low speed operation, the engine state expected from the requested lift characteristics and the actual engine state are not matched. Will be avoided immediately. In addition, since the operation state is quickly changed to the low speed operation, the shocking vertical movement of the center tappet 54 is suppressed, and as a result, damage to the center tappet 54, the high lift cam 17, and the springs 56, 56, etc. is avoided. Is done.
[0097]
Further, since the abnormality on the hydraulic control valve 41 side can be determined based on the hydraulic pressure detected by the hydraulic sensor 39, for example, by using the hydraulic sensor 39 and the vibration sensor 42 together, for example, the hydraulic pressure P is a predetermined value. If it is higher than P1 and vibration is detected, an abnormality on the lock mechanism side can be determined. On the other hand, if the hydraulic pressure P is lower than the predetermined value P1 and vibration is detected, it can be determined that there is an abnormality on the hydraulic control valve 41 side. In addition, the determination accuracy of the switching failure in the lock mechanism is improved.
[0098]
In addition, since vibration is detected by the vibration sensor 42 in a predetermined cam angle range where a collision between the center tappet 54 and the high lift cam 17 is expected to occur, the switching accuracy in the lock mechanism is improved. Furthermore, based on the detection signal from the cam angle sensor 83 when the vibration is detected, it is possible to identify which cylinder A1 to A4 has generated the vibration, that is, the switching failure of the lock mechanism. It becomes possible to repair the location. A crank angle sensor may be employed instead of the cam angle sensor 83, and vibration may be detected after setting a predetermined crank angle range as a detection target.
[0099]
In addition, in the operation range from the predetermined engine speed Ne1 to the engine speed Ne2, it is difficult to determine a switching failure by vibration detection. However, since the switching failure determination based on the intake air amount Q is adopted, the switching in the above region is performed. Defects can also be determined. In the operating region where the engine speed is Ne2 or more, since it is possible to determine the switching failure by the vibration sensor 42, the enlargement of the intake amount map stored in the memory of the control unit 80, which has been a problem in the past, is suppressed. .
[0100]
In addition, based on the vibration detected by the vibration sensor 42, for example, even when a switching failure occurs in some of the cylinders A1 to A4 and the deviation between the actual intake air amount Q and the set intake air amount Q1 is small, the lock mechanism It is possible to reliably determine the switching failure at.
[0101]
Further, based on the intake air amount Q, it is possible to determine not only a switching failure from disengagement to engagement but also a switching failure from engagement to disengagement, and the use range is expanded as a system for determining a switching failure.
[0102]
The valve gear according to the above embodiment is an example embodying the present invention, and the present invention is not limited to this, as long as it is within the scope of the above claims. .
[0103]
【The invention's effect】
As described above, according to the present invention, in a valve operating apparatus for an engine in which a valve is directly driven via a tappet divided so as to be freely disengaged, these tappets can be obtained by adopting vibration detection means. The malfunction of the lock mechanism to be engaged and disengaged can be determined, and the determination accuracy can be improved by combining with the oil pressure detecting means and the intake air amount detecting means. The present invention, which can detect an abnormal driving state at an early stage, is widely suitable in the field of vehicles equipped with an engine valve gear.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a cylinder head of an engine according to an embodiment of the present invention.
FIG. 2 is a plan view of a cylinder head assembled with a support member.
FIG. 3 is a view taken in the direction of the arrows in FIG.
FIG. 4 is a perspective view of a center tappet.
FIG. 5 is a perspective view of a side tappet.
FIG. 6 is a longitudinal sectional view of a main part centering on a tappet.
7 is a cross-sectional view taken along the line II in FIG.
FIG. 8 is a control system diagram.
FIG. 9 is a cross-sectional view of an essential part showing an arrangement example of cams and tappets at the time of a low speed operation command and when not locked.
FIG. 10 is a cross-sectional view of an essential part showing an example of arrangement of cams and tappets at the time of high-speed operation command and when locked.
FIG. 11 is a cross-sectional view of the main part showing an arrangement example of cams and tappets at the time of high-speed operation command and when not locked.
FIG. 12 is a diagram illustrating a cam angle range that is a target for detecting vibration;
FIG. 13 is a flowchart for explaining a determination example of switching failure in the lock mechanism.
[Explanation of symbols]
2 Cylinder head
11 Intake valve
12 Exhaust valve
13 Tappet
14 Intake camshaft
15 Exhaust camshaft
16 Low lift cam (second cam)
17 High lift cam (first cam)
32 Tappet guide (guide hole)
33 Cam cap
39 Hydraulic sensor (hydraulic detection means)
41 Hydraulic control valve
42 Vibration sensor (vibration detection means)
54 Center tappet (1st tappet)
55 Side tappet (second tappet)
56 Spring
80 Control unit (control means, switching failure judgment means)
84 Airflow sensor (intake air amount detection means)

Claims (6)

A cylindrical tappet that is slidably received in a guide hole provided in the cylinder head, and a camshaft that includes a cam that drives a valve via the tappet. The lock mechanism is divided into two tappets, a lock mechanism that engages and disengages the first tappet and the second tappet, a spring that biases the first tappet toward the cam side, and a lock mechanism that depends on the operating state of the engine. Control means for controlling the operation, and the camshaft has a first cam corresponding to the first tappet and the second tappet for each tappet and a lift amount smaller than that of the first cam. A second cam, and when the first tappet and the second tappet are in the disengaged state, the second cam and the valve are connected via the second tappet, A valve operating apparatus for an engine configured to connect a first cam and a valve via a first tappet and a second tappet when the two tappets are engaged. Based on a detection signal from the detection means in an operation state in which the vibration detection means for detecting vibration caused by a collision with the one tappet and the lock mechanism is controlled to engage the first tappet and the second tappet. A valve operating apparatus for an engine, comprising: a switching failure determination means for determining a switching failure from the disengaged state of the first tappet and the second tappet to the engaged state by the lock mechanism. The engine valve operating device according to claim 1, wherein the vibration detecting means detects vibration of the camshaft. 3. The valve operating apparatus for an engine according to claim 2, wherein the vibration detecting means is attached to a cam cap that supports the camshaft. The engine detection target time of vibration by the vibration detection means is set to a time when the first cam provided in the vicinity of the detection means is located within a predetermined cam angle range. Valve operating device. The lock mechanism is operated by a hydraulic pressure supplied via a hydraulic control valve and is provided with a hydraulic pressure detection means for detecting the hydraulic pressure. The switching failure determination means is detected by the hydraulic pressure detection means when the lock mechanism is actuated. 3. The valve operating apparatus for an engine according to claim 2, wherein switching failure is determined based on the hydraulic pressure and a detection signal from the vibration detecting means. An intake air amount detecting means for detecting the intake air amount is provided, and the switching failure determining means includes a deviation between the actual intake air amount detected by the intake air amount detecting means at the time of operating the lock mechanism and the set intake air amount, and a vibration detection means. The valve operating apparatus for an engine according to claim 2, wherein a switching failure is determined based on the detection signal.

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